monocrystalline si targets: Topics by WorldWideScience.org

Sample records for monocrystalline si targets

Buried Porous Silicon-Germanium Layers in Monocrystalline Silicon Lattices

Science.gov (United States)

Fathauer, Robert W. (Inventor); George, Thomas (Inventor); Jones, Eric W. (Inventor)

1998-01-01

Monocrystalline semiconductor lattices with a buried porous semiconductor layer having different chemical composition is discussed and monocrystalline semiconductor superlattices with a buried porous semiconductor layers having different chemical composition than that of its monocrystalline semiconductor superlattice are discussed. Lattices of alternating layers of monocrystalline silicon and porous silicon-germanium have been produced. These single crystal lattices have been fabricated by epitaxial growth of Si and Si-Ge layers followed by patterning into mesa structures. The mesa structures are strain etched resulting in porosification of the Si-Ge layers with a minor amount of porosification of the monocrystalline Si layers. Thicker Si-Ge layers produced in a similar manner emitted visible light at room temperature.
Surface Damage Mechanism of Monocrystalline Si Under Mechanical Loading

Science.gov (United States)

Zhao, Qingliang; Zhang, Quanli; To, Suet; Guo, Bing

2017-03-01

Single-point diamond scratching and nanoindentation on monocrystalline silicon wafer were performed to investigate the surface damage mechanism of Si under the contact loading. The results showed that three typical stages of material removal appeared during dynamic scratching, and a chemical reaction of Si with the diamond indenter and oxygen occurred under the high temperature. In addition, the Raman spectra of the various points in the scratching groove indicated that the Si-I to β-Sn structure (Si-II) and the following β-Sn structure (Si-II) to amorphous Si transformation appeared under the rapid loading/unloading condition of the diamond grit, and the volume change induced by the phase transformation resulted in a critical depth (ductile-brittle transition) of cut (˜60 nm ± 15 nm) much lower than the theoretical calculated results (˜387 nm). Moreover, it also led to abnormal load-displacement curves in the nanoindentation tests, resulting in the appearance of elbow and pop-out effects (˜270 nm at 20 s, 50 mN), which were highly dependent on the loading/unloading conditions. In summary, phase transformation of Si promoted surface deformation and fracture under both static and dynamic mechanical loading.
Method of producing buried porous silicon-geramanium layers in monocrystalline silicon lattices

Science.gov (United States)

Fathauer, Robert W. (Inventor); George, Thomas (Inventor); Jones, Eric W. (Inventor)

1997-01-01

Lattices of alternating layers of monocrystalline silicon and porous silicon-germanium have been produced. These single crystal lattices have been fabricated by epitaxial growth of Si and Si--Ge layers followed by patterning into mesa structures. The mesa structures are stain etched resulting in porosification of the Si--Ge layers with a minor amount of porosification of the monocrystalline Si layers. Thicker Si--Ge layers produced in a similar manner emitted visible light at room temperature.
Highly c-axis-oriented monocrystalline Pb(Zr, Ti)O₃ thin films on si wafer prepared by fast cooling immediately after sputter deposition.

Science.gov (United States)

Yoshida, Shinya; Hanzawa, Hiroaki; Wasa, Kiyotaka; Esashi, Masayoshi; Tanaka, Shuji

2014-09-01

We successfully developed sputter deposition technology to obtain a highly c-axis-oriented monocrystalline Pb(Zr, Ti)O3 (PZT) thin film on a Si wafer by fast cooling (~-180°C/min) of the substrate after deposition. The c-axis orientation ratio of a fast-cooled film was about 90%, whereas that of a slow-cooled (~-40°C/min) film was only 10%. The c-axis-oriented monocrystalline Pb(Zr0.5, Ti0.5)O3 films showed reasonably large piezoelectric coefficients, e(31,f) = ~-11 C/m(2), with remarkably small dielectric constants, ϵ(r) = ~220. As a result, an excellent figure of merit (FOM) was obtained for piezoelectric microelectromechanical systems (MEMS) such as a piezoelectric gyroscope. This c-axis orientation technology on Si will extend industrial applications of PZT-based thin films and contribute further to the development of piezoelectric MEMS.
Monocrystalline Heusler Co2FeSi alloy glass-coated microwires: Fabrication and magneto-structural characterization

Science.gov (United States)

Galdun, L.; Ryba, T.; Prida, V. M.; Zhukova, V.; Zhukov, A.; Diko, P.; Kavečanský, V.; Vargova, Z.; Varga, R.

2018-05-01

Large scale production of single crystalline phase of Heusler Co2FeSi alloy microwire is reported. The long microwire (∼1 km) with the metallic nucleus diameter of about 2 μm is characterized by well oriented monocrystalline structure (B2 phase, with the lattice parameter a = 5.615 Å). Moreover, the crystallographic direction [1 0 1] is parallel to the wire's axis along the entire length. Additionally, the wire is characterized by exhibiting a high Curie temperature (Tc > 800 K) and well-defined magnetic anisotropy mainly governed by shape. Electrical resistivity measurement reveals the exponential suppression of the electron-magnon scattering which provides strong evidence on the half-metallic behaviour of this material in the low temperature range.
Characteristics of poly- and mono-crystalline BeO and SiO2 as thermal and cold neutron filters

Science.gov (United States)

Adib, M.; Habib, N.; Bashter, I. I.; Morcos, H. N.; El-Mesiry, M. S.; Mansy, M. S.

2015-09-01

A simple model along with a computer code "HEXA-FILTERS" is used to carry out the calculation of the total cross-sections of BeO and SiO2 having poly or mono-crystalline form as a function of neutron wavelength at room (R.T.) and liquid nitrogen (L.N.) temperatures. An overall agreement is indicated between the calculated neutron cross-sections and experimental data. Calculation shows that 25 cm thick of polycrystalline BeO cooled at liquid nitrogen temperature was found to be a good filter for neutron wavelengths longer than 0.46 nm. While, 50 cm of SiO2, with much less transmission, for neutrons with wavelengths longer than 0.85 nm. It was also found that 10 cm of BeO and 15 cm SiO2 thick mono-crystals cut along their (0 0 2) plane, with 0.5° FWHM on mosaic spread and cooled at L.N., are a good thermal neutron filter, with high effect-to-noise ratio.
Molecular Dynamics Simulation of Nanoindentation-induced Mechanical Deformation and Phase Transformation in Monocrystalline Silicon

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Jian Sheng-Rui

2008-01-01

Full Text Available AbstractThis work presents the molecular dynamics approach toward mechanical deformation and phase transformation mechanisms of monocrystalline Si(100 subjected to nanoindentation. We demonstrate phase distributions during loading and unloading stages of both spherical and Berkovich nanoindentations. By searching the presence of the fifth neighboring atom within a non-bonding length, Si-III and Si-XII have been successfully distinguished from Si-I. Crystallinity of this mixed-phase was further identified by radial distribution functions.
Wafer scale formation of monocrystalline silicon-based Mie resonators via silicon-on-insulator dewetting.

Science.gov (United States)

Abbarchi, Marco; Naffouti, Meher; Vial, Benjamin; Benkouider, Abdelmalek; Lermusiaux, Laurent; Favre, Luc; Ronda, Antoine; Bidault, Sébastien; Berbezier, Isabelle; Bonod, Nicolas

2014-11-25

Subwavelength-sized dielectric Mie resonators have recently emerged as a promising photonic platform, as they combine the advantages of dielectric microstructures and metallic nanoparticles supporting surface plasmon polaritons. Here, we report the capabilities of a dewetting-based process, independent of the sample size, to fabricate Si-based resonators over large scales starting from commercial silicon-on-insulator (SOI) substrates. Spontaneous dewetting is shown to allow the production of monocrystalline Mie-resonators that feature two resonant modes in the visible spectrum, as observed in confocal scattering spectroscopy. Homogeneous scattering responses and improved spatial ordering of the Si-based resonators are observed when dewetting is assisted by electron beam lithography. Finally, exploiting different thermal agglomeration regimes, we highlight the versatility of this technique, which, when assisted by focused ion beam nanopatterning, produces monocrystalline nanocrystals with ad hoc size, position, and organization in complex multimers.
Characteristics of poly- and mono-crystalline BeO and SiO{sub 2} as thermal and cold neutron filters

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Habib, N. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Bashter, I.I. [Physics Department, Faculty of Science, Zagazig University (Egypt); Morcos, H.N.; El-Mesiry, M.S. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Mansy, M.S., E-mail: drmohamedmansy88@hotmail.com [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt)

2015-09-01

Highlights: • Neutron filtering features of BeO and SiO{sub 2} poly- and mono-crystals. • Calculations of the cold and thermal neutron cross sections and transmission with the code “HEXA-FILTERS”. • Optimal mosaic spread, thicknesses and cutting planes for BeO and SiO{sub 2} mono-crystals. - Abstract: A simple model along with a computer code “HEXA-FILTERS” is used to carry out the calculation of the total cross-sections of BeO and SiO{sub 2} having poly or mono-crystalline form as a function of neutron wavelength at room (R.T.) and liquid nitrogen (L.N.) temperatures. An overall agreement is indicated between the calculated neutron cross-sections and experimental data. Calculation shows that 25 cm thick of polycrystalline BeO cooled at liquid nitrogen temperature was found to be a good filter for neutron wavelengths longer than 0.46 nm. While, 50 cm of SiO{sub 2}, with much less transmission, for neutrons with wavelengths longer than 0.85 nm. It was also found that 10 cm of BeO and 15 cm SiO{sub 2} thick mono-crystals cut along their (0 0 2) plane, with 0.5° FWHM on mosaic spread and cooled at L.N., are a good thermal neutron filter, with high effect-to-noise ratio.
Effect of cutting temperature on hardness of SiC and diamond in the nano-cutting process of monocrystalline silicon

Science.gov (United States)

Wang, Jiachun; Li, Yuntao; Liu, Xiaoxuan; Lv, Maoqiang

2016-10-01

In the process of cutting silicon by natural diamond tools, groove wear happens on the flank face of cutting tool frequently.Scholars believe that one of the wear reasons is mechanical scratching effect by hard particles like SiC. To reveal the mechanical scratching mechanism, it is essential to study changes in the mechanical properties of hard particles and diamond, especially the effect of cutting temperature on hardness of diamond and hard particles. Molecular dynamics (MD) model that contact-zone temperature between tool and workpiece was calculated by dividing zone while nano-cutting monocrystalline silicon was established, cutting temperature values in different regions were computed as the simulation was carried out.On this basis, the models of molecular dynamics simulation of SiC and diamond were established separately with setting the initial temperature to room temperature. The laws of length change of C-C bond and Si-C bond varing with increase of simulation temperature were studied. And drawing on predecessors' research on theoretical calculation of hardness of covalent crystals and the relationship between crystal valence electron density and bond length, the curves that the hardness of diamond and SiC varing with bond length were obtained. The effect of temperature on the hardness was calculated. Results show that, local cutting temperature can reach 1300K.The rise in cutting temperature leaded to a decrease in the diamond local atomic clusters hardness,SiC local atomic clusters hardness increased. As the cutting temperature was more than 1100K,diamond began to soften, the local clusters hardness was less than that of SiC.
Comparative study on stress in AlGaN/GaN HEMT structures grown on 6H-SiC, Si and on composite substrates of the 6H-SiC/poly-SiC and Si/poly-SiC

International Nuclear Information System (INIS)

Guziewicz, M; Kaminska, E; Piotrowska, A; Golaszewska, K; Domagala, J Z; Poisson, M-A; Lahreche, H; Langer, R; Bove, P

2008-01-01

The stresses in GaN-based HEMT structures grown on both single crystal 6H SiC(0001) and Si(111) have been compared to these in the HEMT structures grown on new composite substrates engendered as a thin monocrystalline film attached to polycrystalline 3C-SiC substrate. By using HRXRD technique and wafer curvature method we show that stress of monocrystalline layer in composite substrates of the type mono-Si/poly-SiC is lower than 100 MPa and residual stress of epitaxial GaN buffer grown on the composite substrate does not exceed 0.31 GPa, but in the cases of single crystal SiC or Si substrates the GaN buffer stress is compressive in the range of -0.5 to -0.75 GPa. The total stress of the HEMT structure calculated from strains is consistent with the averaged stress of the multilayers stack measured by wafer curvature method. The averaged stress of HEMT structure grown on single crystals is higher than those in structures grown on composites substrates
Amorphization and recrystallization processes in monocrystalline beta silicon carbide thin films

International Nuclear Information System (INIS)

Edmond, J.A.; Withrow, S.P.; Kong, H.S.; Davis, R.F.

1985-01-01

Individual, as well as multiple doses of 27 Al + , 31 P + , 28 Si + , and 28 Si + and 12 C + , were implanted into (100) oriented monocrystalline β-SiC films. The critical energy of approx. =16 eV/atom required for the amorphization of β-SiC via implantation of 27 Al + and 31 P + was determined using the TRIM84 computer program for calculation of the damage-energy profiles coupled with the results of RBS/ion channeling analyses. In order to recrystallize amorphized layers created by the individual implantation of all four ion species, thermal annealing at 1600, 1700, or 1800 0 C was employed. Characterization of the recrystallized layers was performed using XTEM. Examples of SPE regrown layers containing precipitates and dislocation loops, highly faulted-microtwinned regions, and random crystallites were observed
The Covalent Binding of Photosensitive Dyes to Monocrystalline Silicon Surface and Their Spectral Response

Institute of Scientific and Technical Information of China (English)

郭志新; 郝纪祥; 张祖训; 曹子祥

1993-01-01

A chemical method is proposed to bond photo-sensitive dyes directly to the surface of polished monocrystalline silicon. A methincyanine dye and a trimethincyanine dye have been bonded covalently onto silicon surface through Si—N bond, which are characterized by XPS technique and laser Raman spectra. Photovoltaic effect has been observed with the In/dye/n-Si sandwich devices composed of the dye-bonded n-Si wafers. Significant spectral response shows the characteristic absorptance maxima of the bonded dyes.
Rational design of monocrystalline (InP)(y)Ge(5-2y)/Ge/Si(100) semiconductors: synthesis and optical properties.

Science.gov (United States)

Sims, Patrick E; Chizmeshya, Andrew V G; Jiang, Liying; Beeler, Richard T; Poweleit, Christian D; Gallagher, James; Smith, David J; Menéndez, José; Kouvetakis, John

2013-08-21

In this work, we extend our strategy previously developed to synthesize functional, crystalline Si(5-2y)(AlX)y {X = N,P,As} semiconductors to a new class of Ge-III-V hybrid compounds, leading to the creation of (InP)(y)Ge(5-2y) analogues. The compounds are grown directly on Ge-buffered Si(100) substrates using gas source MBE by tuning the interaction between Ge-based P(GeH3)3 precursors and In atoms to yield nanoscale "In-P-Ge3" building blocks, which then confer their molecular structure and composition to form the target solids via complete elimination of H2. The collateral production of reactive germylene (GeH2), via partial decomposition of P(GeH3)3, is achieved by simple adjustment of the deposition conditions, leading to controlled Ge enrichment of the solid product relative to the stoichiometric InPGe3 composition. High resolution XRD, XTEM, EDX, and RBS indicate that the resultant monocrystalline (InP)(y)Ge(5-2y) alloys with y = 0.3-0.7 are tetragonally strained and fully coherent with the substrate and possess a cubic diamond-like structure. Molecular and solid-state ab initio density functional theory (DFT) simulations support the viability of "In-P-Ge3" building-block assembly of the proposed crystal structures, which consist of a Ge parent crystal in which the P atoms form a third-nearest-neighbor sublattice and "In-P" dimers are oriented to exclude energetically unfavorable In-In bonding. The observed InP concentration dependence of the lattice constant is closely reproduced by DFT simulation of these model structures. Raman spectroscopy and ellipsometry are also consistent with the "In-P-Ge3" building-block interpretation of the crystal structure, while the observation of photoluminescence suggests that (InP)(y)Ge(5-2y) may have important optoelectronic applications.
Estimation of the depth resolution of secondary ion mass spectrometry at the interface SiO2/Si

Science.gov (United States)

Kocanda, J.; Fesič, V.; Veselý, M.; Breza, J.; Kadlečíková, M.

1995-08-01

Similarities between the processes that occur during sputtering of monocrystalline Si by reactive O2+ primary ions and the interface SiO2/monocrystalline Si by noble gas ions (e.g., by Ar+) have motivated us to utilize the semiempirical model of P. C. Zalm and C. J. Vriezema [Nucl. Instrum. Methods B 67, 495 (1992)], modified later by M. Petravić, B. G. Svensson, and J. S. Williams [Appl. Phys. Lett. 62, 278 (1993)] to calculate the decay length λb, as defined by J. B. Clegg [Surf. Interface Anal. 10, 322 (1987)], at the SiO2/Si interface. The measured and calculated results agree remarkably well. Inconsistency observed to be larger than 100% for glancing incidence angles confirms limitations of this model that were admitted already by its authors.
Damage-free polishing of monocrystalline silicon wafers without chemical additives

International Nuclear Information System (INIS)

Biddut, A.Q.; Zhang, L.C.; Ali, Y.M.; Liu, Z.

2008-01-01

This investigation explores the possibility and identifies the mechanism of damage-free polishing of monocrystalline silicon without chemical additives. Using high resolution electron microscopy and contact mechanics, the study concludes that a damage-free polishing process without chemicals is feasible. All forms of damages, such as amorphous Si, dislocations and plane shifting, can be eliminated by avoiding the initiation of the β-tin phase of silicon during polishing. When using 50 nm abrasives, the nominal pressure to achieve damage-free polishing is 20 kPa
Optoelectronic enhancement of monocrystalline silicon solar cells by porous silicon-assisted mechanical grooving

Energy Technology Data Exchange (ETDEWEB)

Ben Rabha, Mohamed; Mohamed, Seifeddine Belhadj; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

2011-03-15

One of the most important factors influencing silicon solar cells performances is the front side reflectivity. Consequently, new methods for efficient reduction of this reflectivity are searched. This has always been done by creating a rough surface that enables incident light of being absorbed within the solar cell. Combination of texturization-porous silicon surface treatment was found to be an attractive technical solution for lowering the reflectivity of monocrystalline silicon (c-Si). The texturization of the monocrystalline silicon wafer was carried out by means of mechanical grooving. A specific etching procedure was then applied to form a thin porous silicon layer enabling to remove mechanical damages. This simple and low cost method reduces the total reflectivity from 29% to 7% in the 300 - 950 nm wavelength range and enhances the diffusion length of the minority carriers from 100 {mu}m to 790 {mu}m (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Photocarrier radiometry for predicting the degradation of electrical parameters of monocrystalline silicon (c-Si) solar cell irradiated by 100 KeV proton beams

International Nuclear Information System (INIS)

Song, P.; Liu, J.Y.; Yuan, H.M.; Oliullah, Md.; Wang, F.; Wang, Y.

2016-01-01

In this study, the monocrystalline silicon (c-Si) solar cell irradiated by 100 KeV proton beams at various fluences is investigated. A one-dimensional two-layer carrier density wave model has been developed to estimate the minority carrier lifetime of n-region and p-region of the non-irradiated c-Si solar cell by best fitting with the experimental photocarrier radiometry (PCR) signal (the amplitude and the phase). Furthermore, the lifetime is used to determine the initial defect density of the quasi-neutral region (QNR) of the solar cell to predict its I–V characteristics. The theoretically predicted short-circuit current density (J_s_c), and open-circuit voltage (V_o_c) of the non-irradiated samples are in good agreement with experiment. Then a three-region defect distribution model for the c-Si solar cell irradiated by proton beams is carried out to describe the defect density distribution according to Monte Carlo simulation results and the initial defect density of the non-irradiated sample. Finally, we find that the electrical measurements of J_s_c and V_o_c of the solar cells irradiated at different fluences using 100 KeV proton beams are consistent with the PCR predicting results.
Photocarrier radiometry for predicting the degradation of electrical parameters of monocrystalline silicon (c-Si) solar cell irradiated by 100 KeV proton beams

Energy Technology Data Exchange (ETDEWEB)

Song, P. [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liu, J.Y., E-mail: ljywlj@hit.edu.cn [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); State Key Laboratory of Robotics and System (HIT), Harbin 150001 (China); Yuan, H.M.; Oliullah, Md.; Wang, F. [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Y., E-mail: songpengkevin@126.com [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); State Key Laboratory of Robotics and System (HIT), Harbin 150001 (China)

2016-09-15

In this study, the monocrystalline silicon (c-Si) solar cell irradiated by 100 KeV proton beams at various fluences is investigated. A one-dimensional two-layer carrier density wave model has been developed to estimate the minority carrier lifetime of n-region and p-region of the non-irradiated c-Si solar cell by best fitting with the experimental photocarrier radiometry (PCR) signal (the amplitude and the phase). Furthermore, the lifetime is used to determine the initial defect density of the quasi-neutral region (QNR) of the solar cell to predict its I–V characteristics. The theoretically predicted short-circuit current density (J{sub sc}), and open-circuit voltage (V{sub oc}) of the non-irradiated samples are in good agreement with experiment. Then a three-region defect distribution model for the c-Si solar cell irradiated by proton beams is carried out to describe the defect density distribution according to Monte Carlo simulation results and the initial defect density of the non-irradiated sample. Finally, we find that the electrical measurements of J{sub sc} and V{sub oc} of the solar cells irradiated at different fluences using 100 KeV proton beams are consistent with the PCR predicting results.
Mechanical grooving of oxidized porous silicon to reduce the reflectivity of monocrystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Zarroug, A.; Dimassi, W.; Ouertani, R.; Ezzaouia, H. [Laboratoire de Photovoltaique, Centre des Recherches et des Technologies de l' Energie, BP. 95, Hammam-Lif 2050 (Tunisia)

2012-10-15

In this work, we are interested to use oxidized porous silicon (ox-PS) as a mask. So, we display the creating of a rough surface which enhances the absorption of incident light by solar cells and reduces the reflectivity of monocrystalline silicon (c-Si). It clearly can be seen that the mechanical grooving enables us to elaborate the texturing of monocrystalline silicon wafer. Results demonstrated that the application of a PS layer followed by a thermal treatment under O2 ambient easily gives us an oxide layer of uniform size which can vary from a nanometer to about ten microns. In addition, the Fourier transform infrared (FTIR) spectroscopy investigations of the PS layer illustrates the possibility to realize oxide layer as a mask for porous silicon. We found also that this simple and low cost method decreases the total reflectivity (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Combined Ultrasonic Elliptical Vibration and Chemical Mechanical Polishing of Monocrystalline Silicon

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Liu Defu

2016-01-01

Full Text Available An ultrasonic elliptical vibration assisted chemical mechanical polishing(UEV-CMP is employed to achieve high material removal rate and high surface quality in the finishing of hard and brittle materials such as monocrystalline silicon, which combines the functions of conventional CMP and ultrasonic machining. In theultrasonic elliptical vibration aided chemical mechanical polishingexperimental setup developed by ourselves, the workpiece attached at the end of horn can vibrate simultaneously in both horizontal and vertical directions. Polishing experiments are carried out involving monocrystalline silicon to confirm the performance of the proposed UEV-CMP. The experimental results reveal that the ultrasonic elliptical vibration can increase significantly the material removal rate and reduce dramatically the surface roughness of monocrystalline silicon. It is found that the removal rate of monocrystalline silicon polished by UEV-CMP is increased by approximately 110% relative to that of conventional CMP because a passive layer on the monocrystalline silicon surface, formed by the chemical action of the polishing slurry, will be removed not only by the mechanical action of CMP but also by ultrasonic vibration action. It indicates that the high efficiency and high quality CMP of monocrystalline silicon can be performed with the proposed UEV-CMP technique.
Monocrystalline silicon solar cells applied in photovoltaic system

OpenAIRE

L.A. Dobrzański; A. Drygała; M. Giedroć; M. Macek

2012-01-01

Purpose: The aim of the paper is to fabricate the monocrystalline silicon solar cells using the conventional technology by means of screen printing process and to make of them photovoltaic system.Design/methodology/approach: The investigation of current – voltage characteristic to determinate basic electrical properties of monocrystalline silicon solar cells were investigated under Standard Test Condition. Photovoltaic module was produced from solar cells with the largest short-circuit curren...
Tracer diffusion studies of 26Mg, 30Si and 18O in single crystal forsterite (Mg2SiO4) and of 18O in single crystal SiO2

International Nuclear Information System (INIS)

Schachtner, R.

1981-01-01

Tracer diffusion coefficients of Mg, Si and O in monocrystalline forsterite were determined by Sims as a function of temperature and crystal orientation. Former results on oxygen diffusion in SiO 2 single crystals using nuclear activation methods were confirmed by Sims data. The influence of crystal defects and impurities is discussed. (TW)
Solar cells, structures including organometallic halide perovskite monocrystalline films, and methods of preparation thereof

KAUST Repository

Bakr, Osman M.

2017-03-02

Embodiments of the present disclosure provide for solar cells including an organometallic halide perovskite monocrystalline film (see fig. 1.1B), other devices including the organometallic halide perovskite monocrystalline film, methods of making organometallic halide perovskite monocrystalline film, and the like.
High frequency guided wave propagation in monocrystalline silicon wafers

OpenAIRE

Pizzolato, M.; Masserey, B.; Robyr, J. L.; Fromme, P.

2017-01-01

Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. The cutting process can introduce micro-cracks in the thin wafers and lead to varying thickness. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers. The anisotropy of the monocrystalline silicon leads to variations of the wave characteristics, depending on the propagation direction relative to the crystal orientation. Full...
Impact of temperature on performance of series and parallel connected mono-crystalline silicon solar cells

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Subhash Chander

2015-11-01

Full Text Available This paper presents a study on impact of temperature on the performance of series and parallel connected mono-crystalline silicon (mono-Si solar cell employing solar simulator. The experiment was carried out at constant light intensity 550 W/m2with cell temperature in the range 25–60 oC for single, series and parallel connected mono-Si solar cells. The performance parameters like open circuit voltage, maximum power, fill factor and efficiency are found to decrease with cell temperature while the short circuit current is observed to increase. The experimental results reveal that silicon solar cells connected in series and parallel combinations follow the Kirchhoff’s laws and the temperature has a significant effect on the performance parameters of solar cell.
Study on the substrate-induced crystallisation of amorphous SiC-precursor ceramics. TIB/A; Untersuchungen zur substratinduzierten Kristallisation amorpher SiC-Precursorkeramiken

Energy Technology Data Exchange (ETDEWEB)

Rau, C.

2000-12-01

In the present thesis the crystallization behaviour of amorphous silicon-carbon materials (SiC{sub x}) was studied. The main topic of the experimental studies formed thereby the epitactical crystallization of thin silicon carbide layers on monocrystalline substrates of silicon carbides or silicon. Furthermore by thermolysis of the polymer amorphous SiC{sub x}-powder was obtained.
Locally-enhanced light scattering by a monocrystalline silicon wafer

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Li Ma

2018-03-01

Full Text Available We study the optical properties of light scattering by a monocrystalline silicon wafer, by using transparent material to replicate its surface structure and illuminating a fabricated sample with a laser source. The experimental results show that the scattering field contains four spots of concentrated intensity with high local energy, and these spots are distributed at the four vertices of a square with lines of intensity linking adjacent spots. After discussing simulations of and theory about the formation of this light scattering, we conclude that the scattering field is formed by the effects of both geometrical optics and physical optics. Moreover, we calculate the central angle of the spots in the light field, and the result indicates that the locally-enhanced intensity spots have a definite scattering angle. These results may possibly provide a method for improving energy efficiency within mono-Si based solar cells.
Monocrystalline zinc oxide films grown by atomic layer deposition

International Nuclear Information System (INIS)

Wachnicki, L.; Krajewski, T.; Luka, G.; Witkowski, B.; Kowalski, B.; Kopalko, K.; Domagala, J.Z.; Guziewicz, M.; Godlewski, M.; Guziewicz, E.

2010-01-01

In the present work we report on the monocrystalline growth of (00.1) ZnO films on GaN template by the Atomic Layer Deposition technique. The ZnO films were obtained at temperature of 300 o C using dietylzinc (DEZn) as a zinc precursor and deionized water as an oxygen precursor. High resolution X-ray diffraction analysis proves that ZnO layers are monocrystalline with rocking curve FWHM of the 00.2 peak equals to 0.07 o . Low temperature photoluminescence shows a sharp and bright excitonic line with FWHM of 13 meV.
Solar cells, structures including organometallic halide perovskite monocrystalline films, and methods of preparation thereof

KAUST Repository

Bakr, Osman; Peng, Wei; Wang, Lingfei

2017-01-01

Embodiments of the present disclosure provide for solar cells including an organometallic halide perovskite monocrystalline film (see fig. 1.1B), other devices including the organometallic halide perovskite monocrystalline film, methods of making
Highly Stable Monocrystalline Silver Clusters for Plasmonic Applications

DEFF Research Database (Denmark)

Novikov, Sergey M.; Popok, Vladimir N.; Evlyukhin, Andrey B.

2017-01-01

Plasmonic sensor configurations utilizing localized plasmon resonances in silver nanostructures typically suffer from the rapid degradation of silver under ambient atmospheric conditions. In this work, we report on the fabrication and detailed characterization of ensembles of monocrystalline silver......-beam technique and characterized by linear spectroscopy, two-photon-excited photoluminescence, surface-enhanced Raman scattering microscopy, and transmission electron, helium ion, and atomic force microscopies. It is found that the fabricated ensembles of monocrystalline silver NPs preserve their plasmonic...... properties (monitored with optical spectroscopy) and strong field enhancements (revealed by surface-enhanced Raman spectroscopy) at least 5 times longer as compared to chemically synthesized silver NPs with similar sizes. The obtained results are of high practical relevance for the further development...
Sunlight-thin nanophotonic monocrystalline silicon solar cells

Science.gov (United States)

Depauw, Valérie; Trompoukis, Christos; Massiot, Inès; Chen, Wanghua; Dmitriev, Alexandre; Cabarrocas, Pere Roca i.; Gordon, Ivan; Poortmans, Jef

2017-09-01

Introducing nanophotonics into photovoltaics sets the path for scaling down the surface texture of crystalline-silicon solar cells from the micro- to the nanoscale, allowing to further boost the photon absorption while reducing silicon material loss. However, keeping excellent electrical performance has proven to be very challenging, as the absorber is damaged by the nanotexturing and the sensitivity to the surface recombination is dramatically increased. Here we realize a light-wavelength-scale nanotextured monocrystalline silicon cell with the confirmed efficiency of 8.6% and an effective thickness of only 830 nm. For this we adopt a self-assembled large-area and industry-compatible amorphous ordered nanopatterning, combined with an advanced surface passivation, earning strongly enhanced solar light absorption while retaining efficient electron collection. This prompts the development of highly efficient flexible and semitransparent photovoltaics, based on the industrially mature monocrystalline silicon technology.
A Power Case Study for Monocrystalline and Polycrystalline Solar Panels in Bursa City, Turkey

Directory of Open Access Journals (Sweden)

Ayşegül Taşçıoğlu

2016-01-01

Full Text Available It was intended to reveal the time dependent power generation under different loads for two different solar panels under the conditions of Bursa province in between August 19 and 25, 2014. The testing sets include solar panels, inverter, multimeter, accumulator, regulator, pyranometer, pyrheliometer, temperature sensor, and datalogger. The efficiency of monocrystalline and polycrystalline solar panels was calculated depending on the climatic data’s measurements. As the result of the study, the average performances of monocrystalline and polycrystalline panels are 42.06 and 39.80 Wh, respectively. It was seen that 87.14 W instantaneous power could be obtained from monocrystalline solar panel and that 80.17 W instantaneous power could be obtained from polycrystalline solar panel under maximum total radiation (1001.13 W/m2. Within this frame, it was determined that monocrystalline solar panel is able to operate more efficiently under the conditions of Bursa compared to polycrystalline solar panel. When the multivariate correlations coefficients were examined statistically, a significant relationship in positive direction was detected between total and direct radiation and ambient temperature on energy generation from monocrystalline and polycrystalline panel.
Fabrication of poly-crystalline Si-based Mie resonators via amorphous Si on SiO2 dewetting.

Science.gov (United States)

Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle; Bidault, Sebastien; Bonod, Nicolas; Abbarchi, Marco

2016-02-07

We report the fabrication of Si-based dielectric Mie resonators via a low cost process based on solid-state dewetting of ultra-thin amorphous Si on SiO2. We investigate the dewetting dynamics of a few nanometer sized layers annealed at high temperature to form submicrometric Si-particles. Morphological and structural characterization reveal the polycrystalline nature of the semiconductor matrix as well as rather irregular morphologies of the dewetted islands. Optical dark field imaging and spectroscopy measurements of the single islands reveal pronounced resonant scattering at visible frequencies. The linewidth of the low-order modes can be ∼20 nm in full width at half maximum, leading to a quality factor Q exceeding 25. These values reach the state-of-the-art ones obtained for monocrystalline Mie resonators. The simplicity of the dewetting process and its cost-effectiveness opens the route to exploiting it over large scales for applications in silicon-based photonics.
Solution-Grown Monocrystalline Hybrid Perovskite Films for Hole-Transporter-Free Solar Cells

KAUST Repository

Peng, Wei

2016-03-02

High-quality perovskite monocrystalline films are successfully grown through cavitation-triggered asymmetric crystallization. These films enable a simple cell structure, ITO/CH3NH3PbBr3/Au, with near 100% internal quantum efficiency, promising power conversion efficiencies (PCEs) >5%, and superior stability for prototype cells. Furthermore, the monocrystalline devices using a hole-transporter-free structure yield PCEs ≈6.5%, the highest among other similar-structured CH3NH3PbBr3 solar cells to date.
In vitro study of color stability of polycrystalline and monocrystalline ceramic brackets

OpenAIRE

de Oliveira, Cibele Braga; Maia, Luiz Guilherme Martins; Santos-Pinto, Ary; Gandini J?nior, Luiz Gonzaga

2014-01-01

OBJECTIVE: The aim of this in vitro study was to analyze color stability of monocrystalline and polycrystalline ceramic brackets after immersion in dye solutions. METHODS: Seven ceramic brackets of four commercial brands were tested: Two monocrystalline and two polycrystalline. The brackets were immersed in four dye solutions (coffee, red wine, Coke and black tea) and in artificial saliva for the following times: 24 hours, 7, 14 and 21 days, respectively. Color changes were measured by a...
Studies of mono-crystalline CVD diamond pixel detectors

CERN Document Server

Bartz, E; Atramentov, O; Yang, Z; Hall-Wilton, R; Schnetzer, S; Patel, R; Bugg, W; Hebda, P; Halyo, V; Hunt, A; Marlow, D; Steininger, H; Ryjov, V; Hits, D; Spanier, S; Pernicka, M; Johns, W; Doroshenko, J; Hollingsworth, M; Harrop, B; Farrow, C; Stone, R

2011-01-01

The Pixel Luminosity Telescope (PLT) is a dedicated luminosity monitor, presently under construction, for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). It measures the particle flux in several three layered pixel diamond detectors that are aligned precisely with respect to each other and the beam direction. At a lower rate it also performs particle track position measurements. The PLTs mono-crystalline CVD diamonds are bump-bonded to the same readout chip used in the silicon pixel system in CMS. Mono-crystalline diamond detectors have many attributes that make them desirable for use in charged particle tracking in radiation hostile environments such as the LHC. In order to further characterize the applicability of diamond technology to charged particle tracking we performed several tests with particle beams that included a measurement of the intrinsic spatial resolution with a high resolution beam telescope. Published by Elsevier B.V.
Studies of mono-crystalline CVD diamond pixel detectors

Energy Technology Data Exchange (ETDEWEB)

Bugg, W. [University of Tennessee, Knoxville (United States); Hollingsworth, M., E-mail: mhollin3@utk.edu [University of Tennessee, Knoxville (United States); Spanier, S.; Yang, Z. [University of Tennessee, Knoxville (United States); Bartz, E.; Doroshenko, J.; Hits, D.; Schnetzer, S.; Stone, R.; Atramentov, O.; Patel, R.; Barker, A. [Rutgers University, Piscataway (United States); Hall-Wilton, R.; Ryjov, V.; Farrow, C. [CERN, Geneva (Switzerland); Pernicka, M.; Steininger, H. [HEPHY, Vienna (Austria); Johns, W. [Vanderbilt University, Nashville (United States); Halyo, V.; Harrop, B. [Princeton University, Princeton (United States); and others

2011-09-11

The Pixel Luminosity Telescope (PLT) is a dedicated luminosity monitor, presently under construction, for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). It measures the particle flux in several three layered pixel diamond detectors that are aligned precisely with respect to each other and the beam direction. At a lower rate it also performs particle track position measurements. The PLT's mono-crystalline CVD diamonds are bump-bonded to the same readout chip used in the silicon pixel system in CMS. Mono-crystalline diamond detectors have many attributes that make them desirable for use in charged particle tracking in radiation hostile environments such as the LHC. In order to further characterize the applicability of diamond technology to charged particle tracking we performed several tests with particle beams that included a measurement of the intrinsic spatial resolution with a high resolution beam telescope.
Enhancing potency of siRNA targeting fusion genes by optimization outside of target sequence.

Science.gov (United States)

Gavrilov, Kseniya; Seo, Young-Eun; Tietjen, Gregory T; Cui, Jiajia; Cheng, Christopher J; Saltzman, W Mark

2015-12-01

Canonical siRNA design algorithms have become remarkably effective at predicting favorable binding regions within a target mRNA, but in some cases (e.g., a fusion junction site) region choice is restricted. In these instances, alternative approaches are necessary to obtain a highly potent silencing molecule. Here we focus on strategies for rational optimization of two siRNAs that target the junction sites of fusion oncogenes BCR-ABL and TMPRSS2-ERG. We demonstrate that modifying the termini of these siRNAs with a terminal G-U wobble pair or a carefully selected pair of terminal asymmetry-enhancing mismatches can result in an increase in potency at low doses. Importantly, we observed that improvements in silencing at the mRNA level do not necessarily translate to reductions in protein level and/or cell death. Decline in protein level is also heavily influenced by targeted protein half-life, and delivery vehicle toxicity can confound measures of cell death due to silencing. Therefore, for BCR-ABL, which has a long protein half-life that is difficult to overcome using siRNA, we also developed a nontoxic transfection vector: poly(lactic-coglycolic acid) nanoparticles that release siRNA over many days. We show that this system can achieve effective killing of leukemic cells. These findings provide insights into the implications of siRNA sequence for potency and suggest strategies for the design of more effective therapeutic siRNA molecules. Furthermore, this work points to the importance of integrating studies of siRNA design and delivery, while heeding and addressing potential limitations such as restricted targetable mRNA regions, long protein half-lives, and nonspecific toxicities.
Primary design of Si cooling arm structure in ICF cryogenic target

International Nuclear Information System (INIS)

Zhang Yong; Yi Yong; Tang Changhuan; Zhang Jicheng

2013-01-01

According to the requirement of the cryogenic target system to the Si cooling arm structure, the Si cooling arm was primarily designed based on the USA National Ignition Facility (NIF) target. A new three-dimensional model of Si cooling arm was developed by SolidWorks software, and the simulation and analysis of Si cooling arm in aspect of mechanical property, thermal response and assembly were made based on the model. A law about the effect of the arm length of Si cooling arm and the width and the length of bifurcation on Si cooling arm was achieved. The research may provide the theoretical foundation and reference for the further improvement of cryogenic target. (authors)

CVD-Based Valence-Mending Passivation for Crystalline-Si Solar Cells

Energy Technology Data Exchange (ETDEWEB)

Tao, Meng [Arizona State Univ., Mesa, AZ (United States)

2015-03-01

The objective of this project is to investigate a new surface passivation technique, valence-mending passivation, for its applications in crystalline-Si solar cells to achieve significant efficiency improvement and cost reduction. As the enabling technique, the project includes the development of chemical vapor deposition recipes to passivate textured Si(100) and multicrystalline-Si surfaces by sulfur and the characterization of the passivated Si surfaces, including thermal stability, Schottky barrier height, contact resistance and surface recombination. One important application is to replace the Ag finger electrode in Si cells with Al to reduce cost, by ~$0.1/Wp, and allow terawatt-scale deployment of crystalline-Si solar cells. These all-Al Si cells require a low-temperature metallization process for the Al electrode, to be compatible with valence-mending passivation and to prevent Al diffusion into n-type Si. Another application is to explore valence-mending passivation of grain boundaries in multicrystalline Si by diffusing sulfur into grain boundaries, to reduce the efficiency gas between monocrystalline-Si solar cells and multicrystalline-Si cells. The major accomplishments of this project include: 1) Demonstration of chemical vapor deposition processes for valence-mending passivation of both monocrystalline Si(100) and multicrystalline Si surfaces. Record Schottky barriers have been demonstrated, with the new record-low barrier of less than 0.08 eV between Al and sulfur-passivated n-type Si(100) and the new record-high barrier of 1.14 eV between Al and sulfur-passivated p-type Si(100). On the textured p-type monocrystalline Si(100) surface, the highest barrier with Al is 0.85 eV by valence-mending passivation. 2) Demonstration of a low-temperature metallization process for Al in crystalline-Si solar cells. The new metallization process is based on electroplating of Al in a room-temperature ionic liquid. The resistivity of the electroplated Al is ~7×10–6
Vacuum deposition and pulsed modification of Ge thin films on Si. Structure and photoluminescence

International Nuclear Information System (INIS)

Batalov, R.I.; Bayazitov, R.M.; Novikov, G.A.; Shustov, V.A.; Bizyaev, D.A.; Gajduk, P.I.; Ivlev, G.D.; Prokop'ev, S.L.

2013-01-01

Vacuum deposition of Ge thin films onto Si substrates by magnetron sputtering was studied. During deposition sputtering time and substrate temperature were varied. Nanosecond pulsed annealing of deposited films by powerful laser or ion beams was performed. The dependence of the structure and optical properties of Ge/Si films on parameters of pulsed treatments was investigated. Optimum parameters of deposition and pulsed treatments resulting into light emitting monocrystalline Ge/Si layers are determined. (authors)
Kinetic analysis of the effects of target structure on siRNA efficiency

Science.gov (United States)

Chen, Jiawen; Zhang, Wenbing

2012-12-01

RNAi efficiency for target cleavage and protein expression is related to the target structure. Considering the RNA-induced silencing complex (RISC) as a multiple turnover enzyme, we investigated the effect of target mRNA structure on siRNA efficiency with kinetic analysis. The 4-step model was used to study the target cleavage kinetic process: hybridization nucleation at an accessible target site, RISC-mRNA hybrid elongation along with mRNA target structure melting, target cleavage, and enzyme reactivation. At this model, the terms accounting for the target accessibility, stability, and the seed and the nucleation site effects are all included. The results are in good agreement with that of experiments which show different arguments about the structure effects on siRNA efficiency. It shows that the siRNA efficiency is influenced by the integrated factors of target's accessibility, stability, and the seed effects. To study the off-target effects, a simple model of one siRNA binding to two mRNA targets was designed. By using this model, the possibility for diminishing the off-target effects by the concentration of siRNA was discussed.
a-Si:H crystallization from isothermal annealing and its dependence on the substrate used

Energy Technology Data Exchange (ETDEWEB)

Rojas-Lopez, M., E-mail: marlonrl@yahoo.com.mx [CIBA-Tlaxcala, Instituto Politecnico Nacional, Tepetitla, Tlax. 90700 (Mexico); Orduna-Diaz, A.; Delgado-Macuil, R.; Gayou, V.L.; Bibbins-Martinez, M. [CIBA-Tlaxcala, Instituto Politecnico Nacional, Tepetitla, Tlax. 90700 (Mexico); Torres-Jacome, A.; Trevino-Palacios, C.G. [INAOE, Tonantzintla, Puebla, Pue. 72000 (Mexico)

2010-10-25

We present hydrogenated amorphous silicon (a-Si:H) films which were deposited on two different substrates (glass and mono-crystalline silicon) after an isothermal annealing treatment at 250 deg. C for up to 14 h. The annealed amorphous films were analyzed using atomic force microscopy, Raman and FTIR spectroscopy. Films deposited on glass substrate experienced an amorphous-crystalline phase transition after annealing because of the metal-induced crystallization effect, reaching approximately 70% conversion after 14 h of annealing. An absorption frequency of the TO-phonon mode that varies systematically with the substoichiometry of the silicon oxide in the 1046-1170 cm{sup -1} region was observed, revealing the reactivity of the film with the annealing time. For similar annealing time, films deposited on mono-crystalline silicon substrate remained mainly amorphous with minimal Si-crystalline formation. Therefore, the crystalline formations and the shape of the films surfaces depends on the annealing time as well as on the substrate employed during the deposition process of the a-Si:H film.
Targeted Sterically Stabilized Phospholipid siRNA Nanomedicine for Hepatic and Renal Fibrosis

Directory of Open Access Journals (Sweden)

Fatima Khaja

2016-01-01

Full Text Available Since its discovery, small interfering RNA (siRNA has been considered a potent tool for modulating gene expression. It has the ability to specifically target proteins via selective degradation of messenger RNA (mRNA not easily accessed by conventional drugs. Hence, RNA interference (RNAi therapeutics have great potential in the treatment of many diseases caused by faulty protein expression such as fibrosis and cancer. However, for clinical application siRNA faces a number of obstacles, such as poor in vivo stability, and off-target effects. Here we developed a unique targeted nanomedicine to tackle current siRNA delivery issues by formulating a biocompatible, biodegradable and relatively inexpensive nanocarrier of sterically stabilized phospholipid nanoparticles (SSLNPs. This nanocarrier is capable of incorporating siRNA in its core through self-association with a novel cationic lipid composed of naturally occuring phospholipids and amino acids. This overall assembly protects and delivers sufficient amounts of siRNA to knockdown over-expressed protein in target cells. The siRNA used in this study, targets connective tissue growth factor (CTGF, an important regulator of fibrosis in both hepatic and renal cells. Furthermore, asialoglycoprotein receptors are targeted by attaching the galactosamine ligand to the nanocarries which enhances the uptake of nanoparticles by hepatocytes and renal tubular epithelial cells, the major producers of CTGF in fibrosis. On animals this innovative nanoconstruct, small interfering RNA in sterically stabilized phospholipid nanoparticles (siRNA-SSLNP, showed favorable pharmacokinetic properties and accumulated mostly in hepatic and renal tissues making siRNA-SSLNP a suitable system for targeting liver and kidney fibrotic diseases.
Investigating the effect of silicon surface chemical treatment on Al/Si contact properties in GaP/Si solar cells

Science.gov (United States)

Kudryashov, D.; Gudovskikh, A.

2018-03-01

In the present work, experimental studies have been carried out to reveal how chemical treatment of a silicon surface affects the properties of the Al/Si contact. It has been shown that for p-type monocrystalline silicon substrates with a resistivity of 10 ohm cm, it is possible to form an ohmic Al/Si contact by magnetron sputtering of an aluminum thin film and its further annealing at temperatures of 400 - 450 °C. In the range of annealing temperatures of 250 - 400 °C, the Si substrate treatment in the HF solution leads to a significant increase in currents on the current-voltage curves of the Al/Si contact, while in the range of 450 - 700 °C, the effect of chemical treatment of the silicon is not detected.
Chemosensitization of cancer cells by siRNA using targeted nanogel delivery

International Nuclear Information System (INIS)

Dickerson, Erin B; Blackburn, William H; Smith, Michael H; Kapa, Laura B; Lyon, L Andrew; McDonald, John F

2010-01-01

Chemoresistance is a major obstacle in cancer treatment. Targeted therapies that enhance cancer cell sensitivity to chemotherapeutic agents have the potential to increase drug efficacy while reducing toxic effects on untargeted cells. Targeted cancer therapy by RNA interference (RNAi) is a relatively new approach that can be used to reversibly silence genes in vivo by selectively targeting genes such as the epidermal growth factor receptor (EGFR), which has been shown to increase the sensitivity of cancer cells to taxane chemotherapy. However, delivery represents the main hurdle for the broad development of RNAi therapeutics. We report here the use of core/shell hydrogel nanoparticles (nanogels) functionalized with peptides that specially target the EphA2 receptor to deliver small interfering RNAs (siRNAs) targeting EGFR. Expression of EGFR was determined by immunoblotting, and the effect of decreased EGFR expression on chemosensitization of ovarian cancer cells after siRNA delivery was investigated. Treatment of EphA2 positive Hey cells with siRNA-loaded, peptide-targeted nanogels decreased EGFR expression levels and significantly increased the sensitivity of this cell line to docetaxel (P < 0.05). Nanogel treatment of SK-OV-3 cells, which are negative for EphA2 expression, failed to reduce EGFR levels and did not increase docetaxel sensitivity (P > 0.05). This study suggests that targeted delivery of siRNAs by nanogels may be a promising strategy to increase the efficacy of chemotherapy drugs for the treatment of ovarian cancer. In addition, EphA2 is a viable target for therapeutic delivery, and the siRNAs are effectively protected by the nanogel carrier, overcoming the poor stability and uptake that has hindered clinical advancement of therapeutic siRNAs
Luminescence and Morphological Properties of GaN Layers Grown on SiC/Si(111) Substrates

Energy Technology Data Exchange (ETDEWEB)

Sanchez-Garcia, M.A.; Ristic, J.; Calleja, E. [ISOM and Dpto. Ing. Electronica, ETSI Telecomunicacion, Univ. Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Perez-Rodriguez, A.; Serre, C.; Romano-Rodriguez, A.; Morante, J.R. [EME - Electronic Materials and Engineering, Department of Electronics, Universidad de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Koegler, R.; Skorupa, W. [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Rossendorf e.V., 01314 Dresden (Germany); Trampert, A.; Ploog, K.H. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

2002-08-16

This article describes the fabrication of SiC thin films on top of Si(111) substrates by means of a multiple C-ion implantation and the subsequent growth by plasma-assisted molecular beam epitaxy of GaN layers. The stoichiometry of the top SiC layer is controlled by reactive ion etching. Photoluminescence spectra reveal that all GaN layers are under biaxial tensile strain of thermal origin. The photoluminescence efficiency clearly depends on the stoichiometry of the initial SiC layer and on whether AlN buffer layers are used or not. GaN layers grown directly on bare non-stoichiometric SiC layers exhibit the best photoluminescence efficiency but also a high degree of mosaicity, as measured by X-ray diffraction techniques. The nucleation process involved in the initial stages of the growth leads to the formation of large dislocation-free grains with a high PL efficiency and with a higher tensile strain character. Despite the lack of a perfect monocrystalline SiC substrate lattice, high quality GaN microcrystals are obtained. (Abstract Copyright[2002], Wiley Periodicals, Inc.)
Lamb wave propagation in monocrystalline silicon wafers

OpenAIRE

Fromme, P.; Pizzolato, M.; Robyr, J-L; Masserey, B.

2018-01-01

Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. Guided ultrasonic waves offer the potential to efficiently detect micro-cracks in the thin wafers. Previous studies of ultrasonic wave propagation in silicon focused on effects of material anisotropy on bulk ultrasonic waves, but the dependence of the wave propagation characteristics on the material anisotropy is not well understood for Lamb waves. The phase slowness a...
Targeted Delivery of siRNA Therapeutics to Malignant Tumors

Directory of Open Access Journals (Sweden)

Qixin Leng

2017-01-01

Full Text Available Over the past 20 years, a diverse group of ligands targeting surface biomarkers or receptors has been identified with several investigated to target siRNA to tumors. Many approaches to developing tumor-homing peptides, RNA and DNA aptamers, and single-chain variable fragment antibodies by using phage display, in vitro evolution, and recombinant antibody methods could not have been imagined by researchers in the 1980s. Despite these many scientific advances, there is no reason to expect that the ligand field will not continue to evolve. From development of ligands based on novel or existing biomarkers to linking ligands to drugs and gene and antisense delivery systems, several fields have coalesced to facilitate ligand-directed siRNA therapeutics. In this review, we discuss the major categories of ligand-targeted siRNA therapeutics for tumors, as well as the different strategies to identify new ligands.
Use of acoustic waves and x-ray radiation for determination of small deformations in monocrystalline Si wafers

International Nuclear Information System (INIS)

Gavrilov, V.N.; Myasishchev, D.E.; Raitman, E.A.

2006-01-01

The paper describes a new method for determination of inhomogeneous deformations in monocrystalline semiconductor wafers. The physical basis of the method is dynamical scattering of X-rays by ultra-sound waves in the presence of static stresses in the crystal. By solving approximately a modified Takagi-Taupin equation the expressions have been obtained that describe relative variations of the diffraction intensity depending on the deformation gradient, the amplitude of ultra-sound wave and its frequency. The paper exemplifies the use of the method for analyzing the deformations and their distribution near the wafer surface in almost 'perfect' crystals and in oxidized wafers with etched windows. It is shown that the new method of nondestructive control, along with its relative simplicity, possesses high sensitivity allowing relative deformations of crystalline lattice of the order of 10-4-10-5 to be determined. (Authors)
Current developments in CZ Si crystal growing technology; Aktuelle Entwicklungen in der Zuechtungstechnologie von CZ-Si-Kristallen

Energy Technology Data Exchange (ETDEWEB)

Altekrueger, Burkhard; Volk, Michael [PVA TePla AG, Wettenberg (Germany)

2011-02-15

The industrial growing of increasingly large and perfect silicon (Si) monocrystals for applications in microelectronics and photovoltaics requires continuous improvement of process control and growing technology. Continuous adaptation and optimization of system technology in terms of reliability, process flexibility and dimensioning are also necessary. The basic principles of industrial silicon crystal growing and the resultant requirements for the Si process and system technologies are described in the first part of this series of articles. The constantly increasing requirements for the performance and complexity of the electronic circuits (chips) in accordance with Moore's Law mean that the requirements for the perfection and dimensions of monocrystalline Si wafers and Si crystals are also continuously rising. After the introduction of the 300 mm Si wafer generation in recent years, the next Si wafer generation (450 mm) is therefore being discussed already. The technological and economic effects of these constantly increasing requirements for the necessary system technologies will be set out and discussed in the subsequent articles on the basis of current Si CZ crystal growing systems as well as new system concepts. (orig.)
Gene silencing of HPV16 E6/E7 induced by promoter-targeting siRNA in SiHa cells

OpenAIRE

Hong, D; Lu, W; Ye, F; Hu, Y; Xie, X

2009-01-01

Background: Recently, transcriptional gene silencing induced by small interfering RNA (siRNA) was found in mammalian and human cells. However, previous studies focused on endogenous genes. Methods: In this study, we designed siRNA targeting the promoter of human papillomavirus 16 E6/E7 and transfected it into the cervical cancer cell line, SiHa. E6 and E7 mRNA and protein expression were detected in cells treated by promoter-targeting siRNA. Futhermore, cellular growth, proliferation, apoptos...
Variations in thermoelectric power of thin monocrystalline films with conductivity

Science.gov (United States)

Tellier, C. R.; Tosser, A. J.; Hafid, L.

1980-12-01

Starting from the bi-dimensional model for grain boundaries in monocrystalline thin films, the difference in thermoelectric power is expressed in terms of conductivity and energy dependence of the bulk electronic mean free path U. A new procedure is suggested for measuring U.
Functional characterization of endogenous siRNA target genes in Caenorhabditis elegans

Directory of Open Access Journals (Sweden)

Heikkinen Liisa

2008-06-01

Full Text Available Abstract Background Small interfering RNA (siRNA molecules mediate sequence specific silencing in RNA interference (RNAi, a gene regulatory phenomenon observed in almost all organisms. Large scale sequencing of small RNA libraries obtained from C. elegans has revealed that a broad spectrum of siRNAs is endogenously transcribed from genomic sequences. The biological role and molecular diversity of C. elegans endogenous siRNA (endo-siRNA molecules, nonetheless, remain poorly understood. In order to gain insight into their biological function, we annotated two large libraries of endo-siRNA sequences, identified their cognate targets, and performed gene ontology analysis to identify enriched functional categories. Results Systematic trends in categorization of target genes according to the specific length of siRNA sequences were observed: 18- to 22-mer siRNAs were associated with genes required for embryonic development; 23-mers were associated uniquely with post-embryonic development; 24–26-mers were associated with phosphorus metabolism or protein modification. Moreover, we observe that some argonaute related genes associate with siRNAs with multiple reads. Sequence frequency graphs suggest that different lengths of siRNAs share similarities in overall sequence structure: the 5' end begins with G, while the body predominates with U and C. Conclusion These results suggest that the lengths of endogenous siRNA molecules are consequential to their biological functions since the gene ontology categories for their cognate mRNA targets vary depending upon their lengths.
The Seebeck coefficient of monocrystalline α-SiC and polycrystalline β-SiC measured at 300-533 K

Science.gov (United States)

Abu-Ageel, N.; Aslam, M.; Ager, R.; Rimai, L.

2000-01-01

The temperature dependence of the Seebeck coefficient of polycrystalline icons/Journals/Common/beta" ALT="beta" ALIGN="TOP"/> -SiC films deposited on quartz substrates by laser ablation and of commercially available icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> -SiC wafers is reported in a temperature range of 300-533 K for the first time. The Seebeck emf of icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> -SiC substrates and icons/Journals/Common/beta" ALT="beta" ALIGN="TOP"/> -SiC samples ranges between -9 µV °C-1 and -108 µV °C-1 which is higher than that of commercial Pt thermocouples.
Spectral structure of the X-ray stimulated phosphorescence of monocrystalline ZnSe

Energy Technology Data Exchange (ETDEWEB)

Degoda, V. Ya., E-mail: degoda@univ.kiev.ua [Taras Shevchenko Kyiv National University, Physics Department, 03680 Kyiv (Ukraine); Pavlova, N. Yu., E-mail: pavlovan7@gmail.com [The National Pedagogical Dragomanov University, Pyrogova 9, 01601 Kyiv (Ukraine); Podust, G.P., E-mail: vasylenkog379@gmail.com [Taras Shevchenko Kyiv National University, Physics Department, 03680 Kyiv (Ukraine); Sofiienko, A.O., E-mail: asofienko@gmail.com [University of Bergen, Allegaten 55, PO Box 7803, 5020 Bergen (Norway)

2015-05-15

This work presents the extensive experimental studies of the X-ray stimulated luminescence, conductivity, phosphorescence and electric current relaxation, and the thermally stimulated luminescence and conductivity of monocrystalline ZnSe. It was found that the luminescence emission band with a maximum at 635 nm is a combination of at least three emission bands and that the appropriate recombination centres implement both electronic and hole recombination mechanisms. We propose an energy model of the traps and recombination centres in monocrystalline ZnSe and show that the majority of the generated free electrons and holes recombine in the luminescence centres with an estimated probability of 94.3% and that only a small fraction (5.7%) of generated charge carriers are accumulated in traps during the X-ray excitation of the ZnSe sample. - Highlights: • ZnSe has intensive X-ray luminescence and phosphorescence in the spectral range from 600 nm to 1000 nm. • We measured the phosphorescence of ZnSe for different wavelengths of 591 nm, 635 nm and 679 nm. • The dominant emission band of ZnSe with a maximum at 635 nm is a combination of at least three emission bands. • We propose and verify an energy model of the traps and recombination centres in monocrystalline ZnSe.
Electrical properties of the n-ZnO/c-Si heterojunction prepared by chemical spray pyrolysis

International Nuclear Information System (INIS)

Romero, R.; Lopez, M.C.; Leinen, D.; Martin, F.; Ramos-Barrado, J.R.

2004-01-01

Electrical, structural and compositional properties of n-ZnO/c-Si heterojunctions prepared by chemical spray pyrolysis on single-crystal n-type and p-type monocrystalline silicon(1 0 0) substrates are examined with the C-V method and admittance spectroscopy at temperature ranges between 223 and 373 K. The n-ZnO/c-Si heterojunctions show a height barrier consistent with the difference in energy of the work functions of Si and ZnO; however, the n-ZnO:Al/c-Si heterojunctions present a more complex behavior due to the defects at or near the n-ZnO:Al/c-Si interface, causing a Fermi energy pinning
Targeted delivery of anti-coxsackievirus siRNAs using ligand-conjugated packaging RNAs.

Science.gov (United States)

Zhang, Huifang M; Su, Yue; Guo, Songchuan; Yuan, Ji; Lim, Travis; Liu, Jing; Guo, Peixuan; Yang, Decheng

2009-09-01

Coxsackievirus B3 (CVB3) is a common pathogen of myocarditis. We previously synthesized a siRNA targeting the CVB3 protease 2A (siRNA/2A) gene and achieved reduction of CVB3 replication by 92% in vitro. However, like other drugs under development, CVB3 siRNA faces a major challenge of targeted delivery. In this study, we investigated a novel approach to deliver CVB3 siRNAs to a specific cell population (e.g. HeLa cells containing folate receptor) using receptor ligand (folate)-linked packaging RNA (pRNA) from bacterial phage phi29. pRNA monomers can spontaneously form dimers and multimers under optimal conditions by base-pairing between their stem loops. By covalently linking a fluorescence-tag to folate, we delivered the conjugate specifically to HeLa cells without the need of transfection. We further demonstrated that pRNA covalently conjugated to siRNA/2A achieved an equivalent antiviral effect to that of the siRNA/2A alone. Finally, the drug targeted delivery was further evaluated by using pRNA monomers or dimers, which carried both the siRNA/2A and folate ligand and demonstrated that both of them strongly inhibited CVB3 replication. These data indicate that pRNA as a siRNA carrier can specifically deliver the drug to target cells via its ligand and specific receptor interaction and inhibit virus replication effectively.
Evaluation of frictional resistance between monocrystalline (ICE brakcets and Stainless Steel, Beta TMA and NiTiarch wires

Directory of Open Access Journals (Sweden)

Meysam Mirzaie

2013-09-01

Full Text Available Introduction: When using sliding mechanics for space closure during orthodontic treatment, friction occurs at the bracket-wire interface. The aim of this study was to evaluate the frictional resistance between monocrystalline (ICE brackets and Stainless Steel, Beta TMA and NiTi wires. Methods: In this experimental study, we used 5 different types of orthodontic wires. Brackets and wires were divided in to 5 groups: 1-(monocrystalline+stainless steel 18 2–(monocrystalline+stainless steel 19×25 3-(monocrystalline+Beta-TMA 4–(monocrystalline+Beta TMA 19×25 5-(monocrystalline+NiTi 18. Instron Universal Testing Machine was used to investigate the static frictional resistance. The angulation between bracket and wire was 0 and the wires were pulled through the slots at a speed of 10 mm/min. Tests were performed 10 times for each group in artificial saliva. The average of 10 forces recorded was considered as static friction. One-way ANOVA and SPSS Version 18 and LSD post hoc test were used to evaluate the results of the study. Results: The mean static frictional force for each group was: group1: 0.82 ± 0.14, group 2: 1.09 ± 0.30, group 3: 0.87 ± 0.53, group 4: 1.9 ± 1.16, group 5: 1.42 ± 0.30. There was a significant difference when comparing the two groups of similar wires in terms of shape (round or rectangular cross-section as when comparing Beta TMA 18 and 19×25 arch wires with each other, the obtained p-value was 0.023, while the obtained p-value for the comparison of stainles steel arch wires was 0.034 . Conclusions: The result of this study shows that Stainless Steel 18 wires generate the least amount of friction and round wires produce less friction than the rectangular wires. Beta TMA wires generate the highest amount of friction.

Targeted siRNA Delivery and mRNA Knockdown Mediated by Bispecific Digoxigenin-binding Antibodies

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Britta Schneider

2012-01-01

Full Text Available Bispecific antibodies (bsAbs that bind to cell surface antigens and to digoxigenin (Dig were used for targeted small interfering RNA (siRNA delivery. They are derivatives of immunoglobulins G (IgGs that bind tumor antigens, such as Her2, IGF1-R, CD22, and LeY, with stabilized Dig-binding variable domains fused to the C-terminal ends of the heavy chains. siRNA that was digoxigeninylated at its 3′end was bound in a 2:1 ratio to the bsAbs. These bsAb–siRNA complexes delivered siRNAs specifically to cells that express the corresponding antigen as demonstrated by flow cytometry and confocal microscopy. The complexes internalized into endosomes and Dig-siRNAs separated from bsAbs, but Dig-siRNA was not released into the cytoplasm; bsAb-targeting alone was thus not sufficient for effective mRNA knockdown. This limitation was overcome by formulating the Dig-siRNA into nanoparticles consisting of dynamic polyconjugates (DPCs or into lipid-based nanoparticles (LNPs. The resulting complexes enabled bsAb-targeted siRNA-specific messenger RNA (mRNA knockdown with IC50 siRNA values in the low nanomolar range for a variety of bsAbs, siRNAs, and target cells. Furthermore, pilot studies in mice bearing tumor xenografts indicated mRNA knockdown in endothelial cells following systemic co-administration of bsAbs and siRNA formulated in LNPs that were targeted to the tumor vasculature.
Cancer-targeting siRNA delivery from porous silicon nanoparticles.

Science.gov (United States)

Wan, Yuan; Apostolou, Sinoula; Dronov, Roman; Kuss, Bryone; Voelcker, Nicolas H

2014-10-01

Porous silicon nanoparticles (pSiNPs) with tunable pore size are biocompatible and biodegradable, suggesting that they are suitable biomaterials as vehicles for drug delivery. Loading of small interfering RNA (siRNA) into the pores of pSiNPs can protect siRNA from degradation as well as improve the cellular uptake. We aimed to deliver MRP1 siRNA loaded into pSiNPs to glioblastoma cells, and to demonstrate downregulation of MRP1 at the mRNA and protein levels. 50-220 nm pSiNPs with an average pore size of 26 nm were prepared, followed by electrostatic adsorption of siRNA into pores. Oligonucleotide loading and release profiles were investigated; MRP1 mRNA and protein expression, cell viability and cell apoptosis were studied. Approximately 7.7 µg of siRNA was loaded per mg of pSiNPs. Cells readily took up nanoparticles after 30 min incubation. siRNA-loaded pSiNPs were able to effectively downregulate target mRNA (~40%) and protein expression (31%), and induced cell apoptosis and necrosis (33%). siRNA loaded pSiNPs downregulated mRNA and protein expression and induced cell death. This novel siRNA delivery system may pave the way towards developing more effective tumor therapies.
Surface etching technologies for monocrystalline silicon wafer solar cells

Science.gov (United States)

Tang, Muzhi

With more than 200 GW of accumulated installations in 2015, photovoltaics (PV) has become an important green energy harvesting method. The PV market is dominated by solar cells made from crystalline silicon wafers. The engineering of the wafer surfaces is critical to the solar cell cost reduction and performance enhancement. Therefore, this thesis focuses on the development of surface etching technologies for monocrystalline silicon wafer solar cells. It aims to develop a more efficient alkaline texturing method and more effective surface cleaning processes. Firstly, a rapid, isopropanol alcohol free texturing method is successfully demonstrated to shorten the process time and reduce the consumption of chemicals. This method utilizes the special chemical properties of triethylamine, which can form Si-N bonds with wafer surface atoms. Secondly, a room-temperature anisotropic emitter etch-back process is developed to improve the n+ emitter passivation. Using this method, 19.0% efficient screen-printed aluminium back surface field solar cells are developed that show an efficiency gain of 0.15% (absolute) compared with conventionally made solar cells. Finally, state-of-the-art silicon surface passivation results are achieved using hydrogen plasma etching as a dry alternative to the classical hydrofluoric acid wet-chemical process. The effective native oxide removal and the hydrogenation of the silicon surface are shown to be the reasons for the excellent level of surface passivation achieved with this novel method.
MEMS monocrystalline-silicon based thermal devices for chemical and microfluidic applications

NARCIS (Netherlands)

Mihailovic, M.

2011-01-01

This thesis explores the employment of monocrystalline silicon in microsystems as an active material for different thermal functions, such as heat generation and heat transfer by conduction. In chapter 1 applications that need thermal micro devices, micro heaters and micro heat exchangers, are
High frequency guided wave propagation in monocrystalline silicon wafers

Science.gov (United States)

Pizzolato, Marco; Masserey, Bernard; Robyr, Jean-Luc; Fromme, Paul

2017-04-01

Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. The cutting process can introduce micro-cracks in the thin wafers and lead to varying thickness. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers. The anisotropy of the monocrystalline silicon leads to variations of the wave characteristics, depending on the propagation direction relative to the crystal orientation. Full three-dimensional Finite Element simulations of the guided wave propagation were conducted to visualize and quantify these effects for a line source. The phase velocity (slowness) and skew angle of the two fundamental Lamb wave modes (first anti-symmetric mode A0 and first symmetric mode S0) for varying propagation directions relative to the crystal orientation were measured experimentally. Selective mode excitation was achieved using a contact piezoelectric transducer with a custom-made wedge and holder to achieve a controlled contact pressure. The out-of-plane component of the guided wave propagation was measured using a noncontact laser interferometer. Good agreement was found with the simulation results and theoretical predictions based on nominal material properties of the silicon wafer.
Evaluation of frictional resistance between monocrystalline (ICE brakcets and Stainless Steel, Beta TMA and NiTi arch wires

Directory of Open Access Journals (Sweden)

Meysam Mirzaie

2013-09-01

Full Text Available Introduction: When using sliding mechanics for space closure during orthodontic treatment, friction occurs at the bracket-wire interface. The aim of this study was to evaluate the frictional resistance between monocrystalline (ICE brackets and Stainless Steel, Beta TMA and NiTi wires. Methods: In this experimental study, we used 5 different types of orthodontic wires. Brackets and wires were divided in to 5 groups: 1-(monocrystalline+stainless steel 18 2–(monocrystalline+stainless steel 19×25 3-(monocrystalline+Beta-TMA 4–(monocrystalline+Beta TMA 19×25 5-(monocrystalline+NiTi 18. Instron Universal Testing Machine was used to investigate the static frictional resistance. The angulation between bracket and wire was 0 and the wires were pulled through the slots at a speed of 10 mm/min. Tests were performed 10 times for each group in artificial saliva. The average of 10 forces recorded was considered as static friction. One-way ANOVA and SPSS Version 18 and LSD post hoc test were used to evaluate the results of the study. Results: The mean static frictional force for each group was: group1: 0.82±0.14, group 2: 1.09±0.30, group 3: 0.87±0.53, group 4: 1.9±1.16, group 5: 1.42±0.30. There was a significant difference when comparing the two groups of similar wires in terms of shape (round or rectangular cross-section as when comparing Beta TMA 18 and 19×25 arch wires with each other, the obtained p-value was 0.023, while the obtained p-value for the comparison of stainles steel arch wires was 0.034. Conclusions: The result of this study shows that Stainless Steel 18 wires generate the least amount of friction and round wires produce less friction than the rectangular wires. Beta TMA wires generate the highest amount of friction.
In vivo therapeutic potential of Dicer-hunting siRNAs targeting infectious hepatitis C virus.

Science.gov (United States)

Watanabe, Tsunamasa; Hatakeyama, Hiroto; Matsuda-Yasui, Chiho; Sato, Yusuke; Sudoh, Masayuki; Takagi, Asako; Hirata, Yuichi; Ohtsuki, Takahiro; Arai, Masaaki; Inoue, Kazuaki; Harashima, Hideyoshi; Kohara, Michinori

2014-04-23

The development of RNA interference (RNAi)-based therapy faces two major obstacles: selecting small interfering RNA (siRNA) sequences with strong activity, and identifying a carrier that allows efficient delivery to target organs. Additionally, conservative region at nucleotide level must be targeted for RNAi in applying to virus because hepatitis C virus (HCV) could escape from therapeutic pressure with genome mutations. In vitro preparation of Dicer-generated siRNAs targeting a conserved, highly ordered HCV 5' untranslated region are capable of inducing strong RNAi activity. By dissecting the 5'-end of an RNAi-mediated cleavage site in the HCV genome, we identified potent siRNA sequences, which we designate as Dicer-hunting siRNAs (dh-siRNAs). Furthermore, formulation of the dh-siRNAs in an optimized multifunctional envelope-type nano device inhibited ongoing infectious HCV replication in human hepatocytes in vivo. Our efforts using both identification of optimal siRNA sequences and delivery to human hepatocytes suggest therapeutic potential of siRNA for a virus.
In vitro study of color stability of polycrystalline and monocrystalline ceramic brackets.

Science.gov (United States)

de Oliveira, Cibele Braga; Maia, Luiz Guilherme Martins; Santos-Pinto, Ary; Gandini Junior, Luiz Gonzaga

2014-01-01

The aim of this in vitro study was to analyze color stability of monocrystalline and polycrystalline ceramic brackets after immersion in dye solutions. Seven ceramic brackets of four commercial brands were tested: Two monocrystalline and two polycrystalline. The brackets were immersed in four dye solutions (coffee, red wine, Coke and black tea) and in artificial saliva for the following times: 24 hours, 7, 14 and 21 days, respectively. Color changes were measured by a spectrophotometer. Data were assessed by Multivariate Profile Analysis, Analysis of Variance (ANOVA) and Multiple Comparison Tests of means. There was a perceptible change of color in all ceramic brackets immersed in coffee (ΔE* Allure = 7.61, Inspire Ice = 6.09, Radiance = 6.69, Transcend = 7.44), black tea (ΔE* Allure = 6.24, Inspire Ice = 5.21, Radiance = 6.51, Transcend = 6.14) and red wine (ΔE* Allure = 6.49, Inspire Ice = 4.76, Radiance = 5.19, Transcend = 5.64), but no change was noticed in Coke and artificial saliva (ΔE brackets undergo color change when exposed to solutions of coffee, black tea and red wine. However, the same crystalline structure, either monocrystalline or polycrystalline, do not follow the same or a similar pattern in color change, varying according to the bracket fabrication, which shows a lack of standardization in the manufacturing process. Coffee dye produced the most marked color changes after 21 days of immersion for most ceramic brackets evaluated.
Solution-phase epitaxial growth of quasi-monocrystalline cuprous oxide on metal nanowires

NARCIS (Netherlands)

Sciacca, Beniamino; Mann, Sander A.; Tichelaar, Frans D.; Zandbergen, Henny W.; Van Huis, Marijn A.; Garnett, Erik C.

2014-01-01

The epitaxial growth of monocrystalline semiconductors on metal nanostructures is interesting from both fundamental and applied perspectives. The realization of nanostructures with excellent interfaces and material properties that also have controlled optical resonances can be very challenging. Here
Pathways of cellular internalisation of liposomes delivered siRNA and effects on siRNA engagement with target mRNA and silencing in cancer cells.

Science.gov (United States)

Alshehri, Abdullah; Grabowska, Anna; Stolnik, Snow

2018-02-28

Design of an efficient delivery system is a generally recognised bottleneck in translation of siRNA technology into clinic. Despite research efforts, cellular processes that determine efficiency of siRNA silencing achieved by different delivery formulations remain unclear. Here, we investigated the mechanism(s) of cellular internalisation of a model siRNA-loaded liposome system in a correlation to the engagement of delivered siRNA with its target and consequent silencing by adopting siRNA molecular beacon technology. Probing of cellular internalisation pathways by a panel of pharmacological inhibitors indicated that clathrin-mediated (dynamin-dependent) endocytosis, macropinocytosis (dynamine independent), and cell membrane cholesterol dependent process(es) (clathrin and caveolea-independent) all play a role in the siRNA-liposomes internalization. The inhibition of either of these entry routes was, in general, mirrored by a reduction in the level of siRNA engagement with its target mRNA, as well as in a reduction of the target gene silencing. A dramatic increase in siRNA engagement with its target RNA was observed on disruption of endosomal membrane (by chloroquine), accompanied with an increased silencing. The work thus illustrates that employing molecular beacon siRNA technology one can start to assess the target RNA engagement - a stage between initial cellular internalization and final gene silencing of siRNA delivery systems.
Tumor-targeted inhibition by a novel strategy - mimoretrovirus expressing siRNA targeting the Pokemon gene.

Science.gov (United States)

Tian, Zhiqiang; Wang, Huaizhi; Jia, Zhengcai; Shi, Jinglei; Tang, Jun; Mao, Liwei; Liu, Hongli; Deng, Yijing; He, Yangdong; Ruan, Zhihua; Li, Jintao; Wu, Yuzhang; Ni, Bing

2010-12-01

Pokemon gene has crucial but versatile functions in cell differentiation, proliferation and tumorigenesis. It is a master regulator of the ARF-HDM2-p53 and Rb-E2F pathways. The facts that the expression of Pokemon is essential for tumor formation and many kinds of tumors over-express the Pokemon gene make it an attractive target for therapeutic intervention for cancer treatment. In this study, we used an RNAi strategy to silence the Pokemon gene in a cervical cancer model. To address the issues involving tumor specific delivery and durable expression of siRNA, we applied the Arg-Gly-Asp (RGD) peptide ligand and polylysine (K(18)) fusion peptide to encapsulate a recombinant retrovirus plasmid expressing a siRNA targeting the Pokemon gene and produced the 'mimoretrovirus'. At charge ratio 2.0 of fusion peptide/plasmid, the mimoretrovirus formed stable and homogenous nanoparticles, and provided complete DNase I protection and complete gel retardation. This nanoparticle inhibited SiHa cell proliferation and invasion, while it promoted SiHa cell apoptosis. The binding of the nanoparticle to SiHa cells was mediated via the RGD-integrin α(v)β(3) interaction, as evidenced by the finding that unconjugated RGD peptide inhibited this binding significantly. This tumor-targeting mimoretrovirus exhibited excellent anti-tumor capacity in vivo in a nude mouse model. Moreover, the mimoretrovirus inhibited tumor growth with a much higher efficiency than recombinant retrovirus expressing siRNA or the K(18)/P4 nanoparticle lacking the RGD peptide. Results suggest that the RNAi/RGD-based mimoretrovirus developed in this study represents a novel anti-tumor strategy that may be applicable to most research involving cancer therapy and, thus, has promising potential as a cervical cancer treatment.
Topotactic Consolidation of Monocrystalline CoZn Hydroxides for Advanced Oxygen Evolution Electrodes.

Science.gov (United States)

Wang, Jing; Tan, Chuan Fu; Zhu, Ting; Ho, Ghim Wei

2016-08-22

We present a room temperature topotactic consolidation of cobalt and zinc constituents into monocrystalline CoZn hydroxide nanosheets, by a localized corrosion of zinc foils with cobalt precursors. By virtue of similar lattice orientation and structure coordination, the hybrid hydroxides amalgamate atomically without phase separation. Importantly, this in situ growth strategy, in combination with configurable percolated nanosheets, renders a high areal density of catalytic sites, immobilized structures, and conductive pathways between the nanosheets and underlying foils-all of which allow monocrystalline CoZn hydroxide nanosheet materials to function as effective electrodes for electrochemical oxygen evolution reactions. This convenient and eco-friendly topotactical transformation approach facilitates high-quality single crystal growth with improved multiphase purity and homogeneity, which can be extended to other transition metals for the fabrication of advanced functional nanocomposites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Impact of target mRNA structure on siRNA silencing efficiency: A large-scale study.

Science.gov (United States)

Gredell, Joseph A; Berger, Angela K; Walton, S Patrick

2008-07-01

The selection of active siRNAs is generally based on identifying siRNAs with certain sequence and structural properties. However, the efficiency of RNA interference has also been shown to depend on the structure of the target mRNA, primarily through studies using exogenous transcripts with well-defined secondary structures in the vicinity of the target sequence. While these studies provide a means for examining the impact of target sequence and structure independently, the predicted secondary structures for these transcripts are often not reflective of structures that form in full-length, native mRNAs where interactions can occur between relatively remote segments of the mRNAs. Here, using a combination of experimental results and analysis of a large dataset, we demonstrate that the accessibility of certain local target structures on the mRNA is an important determinant in the gene silencing ability of siRNAs. siRNAs targeting the enhanced green fluorescent protein were chosen using a minimal siRNA selection algorithm followed by classification based on the predicted minimum free energy structures of the target transcripts. Transfection into HeLa and HepG2 cells revealed that siRNAs targeting regions of the mRNA predicted to have unpaired 5'- and 3'-ends resulted in greater gene silencing than regions predicted to have other types of secondary structure. These results were confirmed by analysis of gene silencing data from previously published siRNAs, which showed that mRNA target regions unpaired at either the 5'-end or 3'-end were silenced, on average, approximately 10% more strongly than target regions unpaired in the center or primarily paired throughout. We found this effect to be independent of the structure of the siRNA guide strand. Taken together, these results suggest minimal requirements for nucleation of hybridization between the siRNA guide strand and mRNA and that both mRNA and guide strand structure should be considered when choosing candidate si
SiO2 Antireflection Coatings Fabricated by Electron-Beam Evaporation for Black Monocrystalline Silicon Solar Cells

Directory of Open Access Journals (Sweden)

Minghua Li

2014-01-01

Full Text Available In this work we prepared double-layer antireflection coatings (DARC by using the SiO2/SiNx:H heterostructure design. SiO2 thin films were deposited by electron-beam evaporation on the conventional solar cell with SiNx:H single-layer antireflection coatings (SARC, while to avoid the coverage of SiO2 on the front side busbars, a steel mask was utilized as the shelter. The thickness of the SiNx:H as bottom layer was fixed at 80 nm, and the varied thicknesses of the SiO2 as top layer were 105 nm and 122 nm. The results show that the SiO2/SiNx:H DARC have a much lower reflectance and higher external quantum efficiency (EQE in short wavelengths compared with the SiNx:H SARC. A higher energy conversion efficiency of 17.80% was obtained for solar cells with SiO2 (105 nm/SiNx:H (80 nm DARC, an absolute conversion efficiency increase of 0.32% compared with the conventional single SiNx:H-coated cells.
Dissolution of Monocrystalline Silicon Nanomembranes and Their Use as Encapsulation Layers and Electrical Interfaces in Water-Soluble Electronics.

Science.gov (United States)

Lee, Yoon Kyeung; Yu, Ki Jun; Song, Enming; Barati Farimani, Amir; Vitale, Flavia; Xie, Zhaoqian; Yoon, Younghee; Kim, Yerim; Richardson, Andrew; Luan, Haiwen; Wu, Yixin; Xie, Xu; Lucas, Timothy H; Crawford, Kaitlyn; Mei, Yongfeng; Feng, Xue; Huang, Yonggang; Litt, Brian; Aluru, Narayana R; Yin, Lan; Rogers, John A

2017-12-26

The chemistry that governs the dissolution of device-grade, monocrystalline silicon nanomembranes into benign end products by hydrolysis serves as the foundation for fully eco/biodegradable classes of high-performance electronics. This paper examines these processes in aqueous solutions with chemical compositions relevant to groundwater and biofluids. The results show that the presence of Si(OH) 4 and proteins in these solutions can slow the rates of dissolution and that ion-specific effects associated with Ca 2+ can significantly increase these rates. This information allows for effective use of silicon nanomembranes not only as active layers in eco/biodegradable electronics but also as water barriers capable of providing perfect encapsulation until their disappearance by dissolution. The time scales for this encapsulation can be controlled by introduction of dopants into the Si and by addition of oxide layers on the exposed surfaces.The former possibility also allows the doped silicon to serve as an electrical interface for measuring biopotentials, as demonstrated in fully bioresorbable platforms for in vivo neural recordings. This collection of findings is important for further engineering development of water-soluble classes of silicon electronics.
Solution-Grown Monocrystalline Hybrid Perovskite Films for Hole-Transporter-Free Solar Cells

KAUST Repository

Peng, Wei; Wang, Lingfei; Banavoth, Murali; Ho, Kang-Ting; Bera, Ashok; Cho, Nam Chul; Kang, Chen-Fang; Burlakov, Victor M.; Pan, Jun; Sinatra, Lutfan; Ma, Chun; Xu, Wei; Shi, Dong; Alarousu, Erkki; Goriely, Alain; He, Jr-Hau; Mohammed, Omar F.; Wu, Tao; Bakr, Osman

2016-01-01

conversion efficiencies (PCEs) >5%, and superior stability for prototype cells. Furthermore, the monocrystalline devices using a hole-transporter-free structure yield PCEs ≈6.5%, the highest among other similar-structured CH3NH3PbBr3 solar cells to date.
[siRNAs with high specificity to the target: a systematic design by CRM algorithm].

Science.gov (United States)

Alsheddi, T; Vasin, L; Meduri, R; Randhawa, M; Glazko, G; Baranova, A

2008-01-01

'Off-target' silencing effect hinders the development of siRNA-based therapeutic and research applications. Common solution to this problem is an employment of the BLAST that may miss significant alignments or an exhaustive Smith-Waterman algorithm that is very time-consuming. We have developed a Comprehensive Redundancy Minimizer (CRM) approach for mapping all unique sequences ("targets") 9-to-15 nt in size within large sets of sequences (e.g. transcriptomes). CRM outputs a list of potential siRNA candidates for every transcript of the particular species. These candidates could be further analyzed by traditional "set-of-rules" types of siRNA designing tools. For human, 91% of transcripts are covered by candidate siRNAs with kernel targets of N = 15. We tested our approach on the collection of previously described experimentally assessed siRNAs and found that the correlation between efficacy and presence in CRM-approved set is significant (r = 0.215, p-value = 0.0001). An interactive database that contains a precompiled set of all human siRNA candidates with minimized redundancy is available at http://129.174.194.243. Application of the CRM-based filtering minimizes potential "off-target" silencing effects and could improve routine siRNA applications.
Femtosecond laser direct writing of monocrystalline hexagonal silver prisms

Energy Technology Data Exchange (ETDEWEB)

Vora, Kevin; Kang, SeungYeon; Moebius, Michael [School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138 (United States); Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138 (United States); Department of Physics, Harvard University, 9 Oxford Street, Cambridge, Massachusetts 02138 (United States)

2014-10-06

Bottom-up growth methods and top-down patterning techniques are both used to fabricate metal nanostructures, each with a distinct advantage: One creates crystalline structures and the other offers precise positioning. Here, we present a technique that localizes the growth of metal crystals to the focal volume of a laser beam, combining advantages from both approaches. We report the fabrication of silver nanoprisms—hexagonal nanoscale silver crystals—through irradiation with focused femtosecond laser pulses. The growth of these nanoprisms is due to a nonlinear optical interaction between femtosecond laser pulses and a polyvinylpyrrolidone film doped with silver nitrate. The hexagonal nanoprisms have bases hundreds of nanometers in size and the crystal growth occurs over exposure times of less than 1 ms (8 orders of magnitude faster than traditional chemical techniques). Electron backscatter diffraction analysis shows that the hexagonal nanoprisms are monocrystalline. The fabrication method combines advantages from both wet chemistry and femtosecond laser direct-writing to grow silver crystals in targeted locations. The results presented in this letter offer an approach to directly positioning and growing silver crystals on a substrate, which can be used for plasmonic devices.
Femtosecond laser direct writing of monocrystalline hexagonal silver prisms

International Nuclear Information System (INIS)

Vora, Kevin; Kang, SeungYeon; Moebius, Michael; Mazur, Eric

2014-01-01

Bottom-up growth methods and top-down patterning techniques are both used to fabricate metal nanostructures, each with a distinct advantage: One creates crystalline structures and the other offers precise positioning. Here, we present a technique that localizes the growth of metal crystals to the focal volume of a laser beam, combining advantages from both approaches. We report the fabrication of silver nanoprisms—hexagonal nanoscale silver crystals—through irradiation with focused femtosecond laser pulses. The growth of these nanoprisms is due to a nonlinear optical interaction between femtosecond laser pulses and a polyvinylpyrrolidone film doped with silver nitrate. The hexagonal nanoprisms have bases hundreds of nanometers in size and the crystal growth occurs over exposure times of less than 1 ms (8 orders of magnitude faster than traditional chemical techniques). Electron backscatter diffraction analysis shows that the hexagonal nanoprisms are monocrystalline. The fabrication method combines advantages from both wet chemistry and femtosecond laser direct-writing to grow silver crystals in targeted locations. The results presented in this letter offer an approach to directly positioning and growing silver crystals on a substrate, which can be used for plasmonic devices.
Structural and electrical properties of epitaxial Si layers prepared by E-beam evaporation

Energy Technology Data Exchange (ETDEWEB)

Dogan, P. [Hahn-Meitner-Institut Berlin, Kekulestr. 5, 12489 Berlin (Germany)], E-mail: pinar.dogan@hmi.de; Rudigier, E.; Fenske, F.; Lee, K.Y.; Gorka, B.; Rau, B.; Conrad, E.; Gall, S. [Hahn-Meitner-Institut Berlin, Kekulestr. 5, 12489 Berlin (Germany)

2008-08-30

In this work, we present structural and electrical properties of thin Si films which are homoepitaxially grown at low substrate temperatures (T{sub s} 450-700 deg. C) by high-rate electron beam evaporation. As substrates, monocrystalline Si wafers with (100) and (111) orientations and polycrystalline Si (poly-Si) seed layers on glass were used. Applying Secco etching, films grown on Si(111) wafers exhibit a decreasing etch pit density with increasing T{sub s}. The best structural quality of the films was obtained on Si(100) wafers. Defect etching on epitaxially grown poly-Si absorbers reveal regions with different crystalline quality. Solar cells have been prepared on both wafers and seed layers. Applying Rapid Thermal Annealing (RTA) and Hydrogen plasma passivation an open circuit voltage of 570 mV for wafer based and 346 mV for seed layer based solar cells have been reached.

Targeted delivery of siRNA to macrophages for anti-inflammatory treatment.

Science.gov (United States)

Kim, Sang-Soo; Ye, Chunting; Kumar, Priti; Chiu, Isaac; Subramanya, Sandesh; Wu, Haoquan; Shankar, Premlata; Manjunath, N

2010-05-01

Inflammation mediated by tumor necrosis factor-alpha (TNF-alpha) and the associated neuronal apoptosis characterizes a number of neurologic disorders. Macrophages and microglial cells are believed to be the major source of TNF-alpha in the central nervous system (CNS). Here, we show that suppression of TNF-alpha by targeted delivery of small interfering RNA (siRNA) to macrophage/microglial cells dramatically reduces lipopolysaccharide (LPS)-induced neuroinflammation and neuronal apoptosis in vivo. Because macrophage/microglia express the nicotinic acetylcholine receptor (AchR) on their surface, we used a short AchR-binding peptide derived from the rabies virus glycoprotein (RVG) as a targeting ligand. This peptide was fused to nona-D-arginine residues (RVG-9dR) to enable siRNA binding. RVG-9dR was able to deliver siRNA to induce gene silencing in macrophages and microglia cells from wild type, but not AchR-deficient mice, confirming targeting specificity. Treatment with anti-TNF-alpha siRNA complexed to RVG-9dR achieved efficient silencing of LPS-induced TNF-alpha production by primary macrophages and microglia cells in vitro. Moreover, intravenous injection with RVG-9dR-complexed siRNA in mice reduced the LPS-induced TNF-alpha levels in blood as well as in the brain, leading to a significant reduction in neuronal apoptosis. These results demonstrate that RVG-9dR provides a tool for siRNA delivery to macrophages and microglia and that suppression of TNF-alpha can potentially be used to suppress neuroinflammation in vivo.
Slow recombination centers in cadmium selenide monocrystalline films

International Nuclear Information System (INIS)

Smyntyna, V.A.

1983-01-01

As a result of annealing when concentration of selenium Vacancies decreases due to their diffusion towards the surface, show recombination K-centers begin to influence the photoelectric properties of monocrystalline cadmium selenide layers. Energy levels of K-centers are located by 0.23-0.25 eV over the valent zone ceiling. The nature of K-centers is determined by the presence in the cadmium selenide layer structure of intrisic defects-cadmium vacancies in contrast to r-centers of slow recombination which are bound with impurities in a semiconductor material
Investigation of the atomic interface structure of mesotaxial Si/CoSi2(100) layers formed by high-dose implantation

International Nuclear Information System (INIS)

Bulle-Lieuwma, C.W.T.; Jong, A.F. de; Vandenhoudt, D.E.W.

1991-01-01

Aligned mesotaxial films of CoSi 2 in monocrystalline (100) oriented Si substrates have been formed by high-dose ion implantation of Co, followed by a high temperature treatment. The atomic structures of both the lower and upper Si/CoSi 2 (100) interfaces of the buried CoSi 2 layer have been investigated by high-resolution electron microscopy (HREM) combined with image simulations. A domain-like structure is observed consisting of areas with different interfaces. In order to derive the atomic configuration, image simulations of different proposed models are presented. By comparing simulated images and HREM images, two different atomic structure models for the Si/CoSi 2 (100) interface have been found. In the first model the interfacial Co atoms are six-fold coordinated and the tetrahedral coordination and bond lengths of silicon atoms are everywhere maintained. In the second model we found evidence for a 2 x 1 interface reconstruction, involving a difference in composition. The interfacial Co atoms are seven-fold coordinated. It is shown that the boundaries between the domains are associated with interfacial dislocations of edge-type with Burgers vectors b a/4 inclined and b = a/2 parallel to the interfacial plane. (author)
siRNAs targeted to certain polyadenylation sites promote specific, RISC-independent degradation of messenger RNAs.

Science.gov (United States)

Vickers, Timothy A; Crooke, Stanley T

2012-07-01

While most siRNAs induce sequence-specific target mRNA cleavage and degradation in a process mediated by Ago2/RNA-induced silencing complex (RISC), certain siRNAs have also been demonstrated to direct target RNA reduction through deadenylation and subsequent degradation of target transcripts in a process which involves Ago1/RISC and P-bodies. In the current study, we present data suggesting that a third class of siRNA exist, which are capable of promoting target RNA reduction that is independent of both Ago and RISC. These siRNAs bind the target messenger RNA at the polyA signal and are capable of redirecting a small amount of polyadenylation to downstream polyA sites when present, however, the majority of the activity appears to be due to inhibition of polyadenylation or deadenylation of the transcript, followed by exosomal degradation of the immature mRNA.
A Ge-Si active target for the measurement of short lifetimes

International Nuclear Information System (INIS)

Amendolia, S.R.; Bedeschi, F.; Bertolucci, E.; Bettoni, D.; Bosisio, L.; Bradaschia, C.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giannetti, P.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Ristori, L.; Scribano, A.; Tenchini, R.; Triggiani, G.; Tonelli, G.; Bologna, G.; D'Ettorre Piazzoli, B.; Mannocchi, G.; Picchi, P.; Consiglio Nazionale delle Ricerche, Turin; D'Angelo, P.; Manfredi, P.F.; Menasce, D.; Meroni, E.; Moroni, L.; Pedrini, D.; Perasso, L.; Sala, S.; Fabbri, F.L.; Enorini, M.; Laurelli, P.; Spillantini, P.; Zallo, A.

1984-01-01

A new Ge-Si active target is presently used in the Na1 experiment at CERN to study photoproduction of charmed particles and to measure their lifetimes. Some general comments on the active target technique are made. (orig.)
Electrically active, doped monocrystalline silicon nanoparticles produced by hot wire thermal catalytic pyrolysis

CSIR Research Space (South Africa)

Scriba, MR

2011-05-01

Full Text Available Doped silicon nanoparticles have successfully been produced by hot wire thermal catalytic pyrolysis at 40 mbar and a filament temperature of 1800 °C, using a mixture of silane and diborane or phosphine. All particles are monocrystalline with shapes...
Soft computing model for optimized siRNA design by identifying off target possibilities using artificial neural network model.

Science.gov (United States)

Murali, Reena; John, Philips George; Peter S, David

2015-05-15

The ability of small interfering RNA (siRNA) to do posttranscriptional gene regulation by knocking down targeted genes is an important research topic in functional genomics, biomedical research and in cancer therapeutics. Many tools had been developed to design exogenous siRNA with high experimental inhibition. Even though considerable amount of work has been done in designing exogenous siRNA, design of effective siRNA sequences is still a challenging work because the target mRNAs must be selected such that their corresponding siRNAs are likely to be efficient against that target and unlikely to accidentally silence other transcripts due to sequence similarity. In some cases, siRNAs may tolerate mismatches with the target mRNA, but knockdown of genes other than the intended target could make serious consequences. Hence to design siRNAs, two important concepts must be considered: the ability in knocking down target genes and the off target possibility on any nontarget genes. So before doing gene silencing by siRNAs, it is essential to analyze their off target effects in addition to their inhibition efficacy against a particular target. Only a few methods have been developed by considering both efficacy and off target possibility of siRNA against a gene. In this paper we present a new design of neural network model with whole stacking energy (ΔG) that enables to identify the efficacy and off target effect of siRNAs against target genes. The tool lists all siRNAs against a particular target with their inhibition efficacy and number of matches or sequence similarity with other genes in the database. We could achieve an excellent performance of Pearson Correlation Coefficient (R=0. 74) and Area Under Curve (AUC=0.906) when the threshold of whole stacking energy is ≥-34.6 kcal/mol. To the best of the author's knowledge, this is one of the best score while considering the "combined efficacy and off target possibility" of siRNA for silencing a gene. The proposed model
Controlling the optical properties of monocrystalline 3C-SiC heteroepitaxially grown on silicon at low temperatures

Science.gov (United States)

Colston, Gerard; Myronov, Maksym

2017-11-01

Cubic silicon carbide (3C-SiC) offers an alternative wide bandgap semiconductor to conventional materials such as hexagonal silicon carbide (4H-SiC) or gallium nitride (GaN) for the detection of UV light and can offer a closely lattice matched virtual substrate for subsequent GaN heteroepitaxy. As 3C-SiC can be heteroepitaxially grown on silicon (Si) substrates its optical properties can be manipulated by controlling the thickness and doping concentrations. The optical properties of 3C-SiC epilayers have been characterized by measuring the transmission of light through suspended membranes. Decreasing the thickness of the 3C-SiC epilayers is shown to shift the absorbance edge to lower wavelengths, a result of the indirect bandgap nature of silicon carbide. This property, among others, can be exploited to fabricate very low-cost, tuneable 3C-SiC based UV photodetectors. This study investigates the effect of thickness and doping concentration on the optical properties of 3C-SiC epilayers grown at low temperatures by a standard Si based growth process. The results demonstrate the potential photonic applications of 3C-SiC and its heterogeneous integration into the Si industry.
Large area isotopic silicon targets for astrophysical reaction rate studies in Si-26

NARCIS (Netherlands)

Greene, JP; Berg, GPA

2005-01-01

For measurements of stellar reaction rates of proton rich nuclei involving resonance levels just above threshold, targets of Si-28 were used in studies of the Si-21(He-4, He-6)Si-26 reaction using the Research Center for Nuclear Physics (RCNP) Ring Cyclotron at Osaka University. Resonance structure
Dual-Functional Nanoparticles Targeting CXCR4 and Delivering Antiangiogenic siRNA Ameliorate Liver Fibrosis.

Science.gov (United States)

Liu, Chun-Hung; Chan, Kun-Ming; Chiang, Tsaiyu; Liu, Jia-Yu; Chern, Guann-Gen; Hsu, Fu-Fei; Wu, Yu-Hsuan; Liu, Ya-Chi; Chen, Yunching

2016-07-05

The progression of liver fibrosis, an intrinsic response to chronic liver injury, is associated with hepatic hypoxia, angiogenesis, abnormal inflammation, and significant matrix deposition, leading to the development of cirrhosis and hepatocellular carcinoma (HCC). Due to the complex pathogenesis of liver fibrosis, antifibrotic drug development has faced the challenge of efficiently and specifically targeting multiple pathogenic mechanisms. Therefore, CXCR4-targeted nanoparticles (NPs) were formulated to deliver siRNAs against vascular endothelial growth factor (VEGF) into fibrotic livers to block angiogenesis during the progression of liver fibrosis. AMD3100, a CXCR4 antagonist that was incorporated into the NPs, served dual functions: it acted as a targeting moiety and suppressed the progression of fibrosis by inhibiting the proliferation and activation of hepatic stellate cells (HSCs). We demonstrated that CXCR4-targeted NPs could deliver VEGF siRNAs to fibrotic livers, decrease VEGF expression, suppress angiogenesis and normalize the distorted vessels in the fibrotic livers in the carbon tetrachloride (CCl4) induced mouse model. Moreover, blocking SDF-1α/CXCR4 by CXCR4-targeted NPs in combination with VEGF siRNA significantly prevented the progression of liver fibrosis in CCl4-treated mice. In conclusion, the multifunctional CXCR4-targeted NPs delivering VEGF siRNAs provide an effective antifibrotic therapeutic strategy.
siRNAs Targeting Viral Protein 5: The Major Capsid Protein of ...

African Journals Online (AJOL)

Purpose: To investigate whether siRNA targeting viral protein 5 (VP5) can become a new treatment for herpes simplex virus type 1 (HSV-1). Methods: Flow cytometry was performed to determine the ratio of siRNA and lipo2000 to reach the highest transfection efficiency. Western blot and q-PCR were performed to determine ...
Use of Monocrystalline Silicon as Tool Material for Highly Accurate Blanking of Thin Metal Foils

International Nuclear Information System (INIS)

Hildering, Sven; Engel, Ulf; Merklein, Marion

2011-01-01

The trend towards miniaturisation of metallic mass production components combined with increased component functionality is still unbroken. Manufacturing these components by forming and blanking offers economical and ecological advantages combined with the needed accuracy. The complexity of producing tools with geometries below 50 μm by conventional manufacturing methods becomes disproportional higher. Expensive serial finishing operations are required to achieve an adequate surface roughness combined with accurate geometry details. A novel approach for producing such tools is the use of advanced etching technologies for monocrystalline silicon that are well-established in the microsystems technology. High-precision vertical geometries with a width down to 5 μm are possible. The present study shows a novel concept using this potential for the blanking of thin copper foils with monocrystallline silicon as a tool material. A self-contained machine-tool with compact outer dimensions was designed to avoid tensile stresses in the brittle silicon punch by an accurate, careful alignment of the punch, die and metal foil. A microscopic analysis of the monocrystalline silicon punch shows appropriate properties regarding flank angle, edge geometry and surface quality for the blanking process. Using a monocrystalline silicon punch with a width of 70 μm blanking experiments on as-rolled copper foils with a thickness of 20 μm demonstrate the general applicability of this material for micro production processes.
Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

KAUST Repository

Ghoneim, Mohamed T.; Fahad, Hossain M.; Hussain, Aftab M.; Rojas, Jhonathan Prieto; Sevilla, Galo T.; Alfaraj, Nasir; Lizardo, Ernesto B.; Hussain, Muhammad Mustafa

2015-01-01

In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.
Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

KAUST Repository

Ghoneim, Mohamed T.

2015-12-11

In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.
Intravenous siRNA of brain cancer with receptor targeting and avidin-biotin technology.

Science.gov (United States)

Xia, Chun-Fang; Zhang, Yufeng; Zhang, Yun; Boado, Ruben J; Pardridge, William M

2007-12-01

The effective delivery of short interfering RNA (siRNA) to brain following intravenous administration requires the development of a delivery system for transport of the siRNA across the brain capillary endothelial wall, which forms the blood-brain barrier in vivo. siRNA was delivered to brain in vivo with the combined use of a receptor-specific monoclonal antibody delivery system, and avidin-biotin technology. The siRNA was mono-biotinylated on either terminus of the sense strand, in parallel with the production of a conjugate of the targeting MAb and streptavidin. Rat glial cells (C6 or RG-2) were permanently transfected with the luciferase gene, and implanted in the brain of adult rats. Following the formation of intra-cranial tumors, the rats were treated with a single intravenous injection of 270 microg/kg of biotinylated siRNA attached to a transferrin receptor antibody via a biotin-streptavidin linker. The intravenous administration of the siRNA caused a 69-81% decrease in luciferase gene expression in the intracranial brain cancer in vivo. Brain delivery of siRNA following intravenous administration is possible with siRNAs that are targeted to brain with the combined use of receptor specific antibody delivery systems and avidin-biotin technology.
Optimizations of siRNA design for the activation of gene transcription by targeting the TATA-box motif.

Directory of Open Access Journals (Sweden)

Miaomiao Fan

Full Text Available Small interfering RNAs (siRNAs are widely used to repress gene expression by targeting mRNAs. Some reports reveal that siRNAs can also activate or inhibit gene expression through targeting the gene promoters. Our group has found that microRNAs (miRNAs could activate gene transcription via interaction with the TATA-box motif in gene promoters. To investigate whether siRNA targeting the same region could upregulate the promoter activity, we test the activating efficiency of siRNAs targeting the TATA-box motif of 16 genes and perform a systematic analysis to identify the common features of the functional siRNAs for effective activation of gene promoters. Further, we try various modifications to improve the activating efficiency of siRNAs and find that it is quite useful to design the promoter-targeting activating siRNA by following several rules such as (a complementary to the TATA-box-centered region; (b UA usage at the first two bases of the antisense strand; (c twenty-three nucleotides (nts in length; (d 2'-O-Methyl (2'-OMe modification at the 3' terminus of the antisense strand; (e avoiding mismatches at the 3' end of the antisense strand. The optimized activating siRNAs potently enhance the expression of interleukin-2 (IL-2 gene in human and mouse primary CD4+ T cells with a long-time effect. Taken together, our study provides a guideline for rational design the promoter-targeting siRNA to sequence-specifically enhance gene expression.
The DoE method as an efficient tool for modeling the behavior of monocrystalline Si-PV module

Science.gov (United States)

Kessaissia, Fatma Zohra; Zegaoui, Abdallah; Boutoubat, Mohamed; Allouache, Hadj; Aillerie, Michel; Charles, Jean-Pierre

2018-05-01

The objective of this paper is to apply the Design of Experiments (DoE) method to study and to obtain a predictive model of any marketed monocrystalline photovoltaic (mc-PV) module. This technique allows us to have a mathematical model that represents the predicted responses depending upon input factors and experimental data. Therefore, the DoE model for characterization and modeling of mc-PV module behavior can be obtained by just performing a set of experimental trials. The DoE model of the mc-PV panel evaluates the predictive maximum power, as a function of irradiation and temperature in a bounded domain of study for inputs. For the mc-PV panel, the predictive model for both one level and two levels were developed taking into account both influences of the main effect and the interactive effects on the considered factors. The DoE method is then implemented by developing a code under Matlab software. The code allows us to simulate, characterize, and validate the predictive model of the mc-PV panel. The calculated results were compared to the experimental data, errors were estimated, and an accurate validation of the predictive models was evaluated by the surface response. Finally, we conclude that the predictive models reproduce the experimental trials and are defined within a good accuracy.
Optimization of Monocrystalline MgxCd1-xTe/MgyCd1-yTe Double-Heterostructure Solar Cells

Science.gov (United States)

Becker, Jacob J.

Polycrystalline CdS/CdTe solar cells continue to dominate the thin-film photovoltaics industry with an achieved record efficiency of over 22% demonstrated by First Solar, yet monocrystalline CdTe devices have received considerably less attention over the years. Monocrystalline CdTe double-heterostructure solar cells show great promise with respect to addressing the problem of low Voc with the passing of the 1 V benchmark. Rapid progress has been made in driving the efficiency in these devices ever closer to the record presently held by polycrystalline thin-films. This achievement is primarily due to the utilization of a remote p-n heterojunction in which the heavily doped contact materials, which are so problematic in terms of increasing non-radiative recombination inside the absorber, are moved outside of the CdTe double heterostructure with two MgyCd1-yTe barrier layers to provide confinement and passivation at the CdTe surfaces. Using this design, the pursuit and demonstration of efficiencies beyond 20% in CdTe solar cells is reported through the study and optimization of the structure barriers, contacts layers, and optical design. Further development of a wider bandgap MgxCd1-xTe solar cell based on the same design is included with the intention of applying this knowledge to the development of a tandem solar cell constructed on a silicon subcell. The exploration of different hole-contact materials--ZnTe, CuZnS, and a-Si:H--and their optimization is presented throughout the work. Devices utilizing a-Si:H hole contacts exhibit open-circuit voltages of up to 1.11 V, a maximum total-area efficiency of 18.5% measured under AM1.5G, and an active-area efficiency of 20.3% for CdTe absorber based devices. The achievement of voltages beyond 1.1V while still maintaining relatively high fill factors with no rollover, either before or after open-circuit, is a promising indicator that this approach can result in devices surpassing the 22% record set by polycrystalline
Dual peptide-mediated targeted delivery of bioactive siRNAs to oral cancer cells in vivo.

Science.gov (United States)

Alexander-Bryant, Angela A; Zhang, Haiwen; Attaway, Christopher C; Pugh, William; Eggart, Laurence; Sansevere, Robert M; Andino, Lourdes M; Dinh, Lu; Cantini, Liliana P; Jakymiw, Andrew

2017-09-01

Despite significant advances in cancer treatment, the prognosis for oral cancer remains poor in comparison to other cancer types, including breast, skin, and prostate. As a result, more effective therapeutic modalities are needed for the treatment of oral cancer. Consequently, in the present study, we examined the feasibility of using a dual peptide carrier approach, combining an epidermal growth factor receptor (EGFR)-targeting peptide with an endosome-disruptive peptide, to mediate targeted delivery of small interfering RNAs (siRNAs) into EGFR-overexpressing oral cancer cells and induce silencing of the targeted oncogene, cancerous inhibitor of protein phosphatase 2A (CIP2A). Fluorescence microscopy, real-time PCR, Western blot analysis, and in vivo bioimaging of mice containing orthotopic xenograft tumors were used to examine the ability of the dual peptide carrier to mediate specific delivery of bioactive siRNAs into EGFR-overexpressing oral cancer cells/tissues. Co-complexation of the EGFR-targeting peptide, GE11R9, with the endosome-disruptive 599 peptide facilitated the specific uptake of siRNAs into oral cancer cells overexpressing EGFR in vitro with optimal gene silencing observed at a 60:30:1 (GE11R9:599:siRNA) molar ratio. Furthermore, when administered systemically to mice bearing xenograft oral tumors, this dual peptide complex mediated increased targeted delivery of siRNAs into tumor tissues in comparison to the 599 peptide alone and significantly enhanced CIP2A silencing. Herein we provide the first report demonstrating the clinical potential of a dual peptide strategy for siRNA-based therapeutics by synergistically mediating the effective targeting and delivery of bioactive siRNAs into EGFR-overexpressing oral cancer cells. Copyright © 2017 Elsevier Ltd. All rights reserved.
Deep Sequencing Insights in Therapeutic shRNA Processing and siRNA Target Cleavage Precision.

Science.gov (United States)

Denise, Hubert; Moschos, Sterghios A; Sidders, Benjamin; Burden, Frances; Perkins, Hannah; Carter, Nikki; Stroud, Tim; Kennedy, Michael; Fancy, Sally-Ann; Lapthorn, Cris; Lavender, Helen; Kinloch, Ross; Suhy, David; Corbau, Romu

2014-02-04

TT-034 (PF-05095808) is a recombinant adeno-associated virus serotype 8 (AAV8) agent expressing three short hairpin RNA (shRNA) pro-drugs that target the hepatitis C virus (HCV) RNA genome. The cytosolic enzyme Dicer cleaves each shRNA into multiple, potentially active small interfering RNA (siRNA) drugs. Using next-generation sequencing (NGS) to identify and characterize active shRNAs maturation products, we observed that each TT-034-encoded shRNA could be processed into as many as 95 separate siRNA strands. Few of these appeared active as determined by Sanger 5' RNA Ligase-Mediated Rapid Amplification of cDNA Ends (5-RACE) and through synthetic shRNA and siRNA analogue studies. Moreover, NGS scrutiny applied on 5-RACE products (RACE-seq) suggested that synthetic siRNAs could direct cleavage in not one, but up to five separate positions on targeted RNA, in a sequence-dependent manner. These data support an on-target mechanism of action for TT-034 without cytotoxicity and question the accepted precision of substrate processing by the key RNA interference (RNAi) enzymes Dicer and siRNA-induced silencing complex (siRISC).Molecular Therapy-Nucleic Acids (2014) 3, e145; doi:10.1038/mtna.2013.73; published online 4 February 2014.

Reductive nanocomplex encapsulation of cRGD-siRNA conjugates for enhanced targeting to cancer cells

Directory of Open Access Journals (Sweden)

Zhou Z

2017-10-01

Full Text Available Zhaoxiu Zhou,* Shuang Liu,* Yanfen Zhang, Xiantao Yang, Yuan Ma, Zhu Guan, Yun Wu, Lihe Zhang, Zhenjun Yang State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, People’s Republic of China *These authors contributed equally to this work Abstract: In this study, through covalent conjugation and lipid material entrapment, a combined modification strategy was established for effective delivery of small interfering RNA (siRNA. Single strands of siRNA targeting to BRAFV600E gene (siMB3 conjugated with cRGD peptide at 3'-terminus or 5'-terminus via cleavable disulfide bond was synthesized and then annealed with corresponding strands to obtain single and bis-cRGD-siRNA conjugates. A cationic lipid material (CLD developed by our laboratory was mixed with the conjugates to generate nanocomplexes; their uniformity and electrical property were revealed by particle size and zeta potential measurement. Compared with CLD/siBraf, CLD/cRGD-siBraf achieved higher cell uptake and more excellent tumor-targeting ability, especially 21 (sense-5′/antisense-3″-cRGD-congjugate nanocomplex. Moreover, they can regulate multiple pathways to varying degree and reduce acidification of endosome. Compared with the gene silencing of different conjugates, single or bis-cRGD-conjugated siRNA showed little differences except 22 (5/5 which cRGD was conjugated at 5'-terminus of antisense strand and sense strand. However bis-cRGD conjugate 21 nanocomplex exhibited better specific target gene silencing at multiple time points. Furthermore, the serum stabilities of the bis-cRGD conjugates were higher than those of the single-cRGD conjugates. In conclusion, all these data suggested that CLD/bis-conjugates, especially CLD/21, can be an effective system for delivery of siRNA to target BRAFV600E gene for therapy of melanoma. Keywords: cRGD-siRNA conjugates, cationic lipids, targeting, silencing, intracellular pathways
Texturization of as-cut p-type monocrystalline silicon wafer using different wet chemical solutions

Science.gov (United States)

Hashmi, Galib; Hasanuzzaman, Muhammad; Basher, Mohammad Khairul; Hoq, Mahbubul; Rahman, Md. Habibur

2018-06-01

Implementing texturization process on the monocrystalline silicon substrate reduces reflection and enhances light absorption of the substrate. Thus texturization is one of the key elements to increase the efficiency of solar cell. Considering as-cut monocrystalline silicon wafer as base substrate, in this work different concentrations of Na2CO3 and NaHCO3 solution, KOH-IPA (isopropyl alcohol) solution and tetramethylammonium hydroxide solution with different time intervals have been investigated for texturization process. Furthermore, saw damage removal process was conducted with 10% NaOH solution, 20 wt% KOH-13.33 wt% IPA solution and HF/nitric/acetic acid solution. The surface morphology of saw damage, saw damage removed surface and textured wafer were observed using optical microscope and field emission scanning electron microscopy. Texturization causes pyramidal micro structures on the surface of (100) oriented monocrystalline silicon wafer. The height of the pyramid on the silicon surface varies from 1.5 to 3.2 µm and the inclined planes of the pyramids are acute angle. Contact angle value indicates that the textured wafer's surface fall in between near-hydrophobic to hydrophobic range. With respect to base material absolute reflectance 1.049-0.75% within 250-800 nm wavelength region, 0.1-0.026% has been achieved within the same wavelength region when textured with 0.76 wt% KOH-4 wt% IPA solution for 20 min. Furthermore, an alternative route of using 1 wt% Na2CO3-0.2 wt% NaHCO3 solution for 50 min has been exploited in the texturization process.
Novel targeted siRNA-loaded hybrid nanoparticles: preparation, characterization and in vitro evaluation.

Science.gov (United States)

Dim, Nneka; Perepelyuk, Maryna; Gomes, Olukayode; Thangavel, Chellappagounder; Liu, Yi; Den, Robert; Lakshmikuttyamma, Ashakumary; Shoyele, Sunday A

2015-09-26

siRNAs have a high potential for silencing critical molecular pathways that are pathogenic. Nevertheless, their clinical application has been limited by a lack of effective and safe nanotechnology-based delivery system that allows a controlled and safe transfection to cytosol of targeted cells without the associated adverse effects. Our group recently reported a very effective and safe hybrid nanoparticle delivery system composing human IgG and poloxamer-188 for siRNA delivery to cancer cells. However, these nanoparticles need to be optimized in terms of particle size, loading capacity and encapsulation efficiency. In the present study, we explored the effects of certain production parameters on particle size, loading capacity and encapsulation efficiency. Further, to make these nanoparticles more specific in their delivery of siRNA, we conjugated anti-NTSR1-mAb to the surface of these nanoparticles to target NTSR1-overexpressing cancer cells. The mechanism of siRNA release from these antiNTSR1-mAb functionalized nanoparticles was also elucidated. It was demonstrated that the concentration of human IgG in the starting nanoprecipitation medium and the rotation speed of the magnetic stirrer influenced the encapsulation efficiency, loading capacity and the size of the nanoparticles produced. We also successfully transformed these nanoparticles into actively targeted nanoparticles by functionalizing with anti-NTSR1-mAb to specifically target NTSR1-overexpressing cancer cells, hence able to avoid undesired accumulation in normal cells. The mechanism of siRNA release from these nanoparticles was elucidated to be by Fickian diffusion. Using flow cytometry and fluorescence microscopy, we were able to confirm the active involvement of NTSR1 in the uptake of these anti-NTSR1-mAb functionalized hybrid nanoparticles by lung adenocarcinoma cells. This hybrid nanoparticle delivery system can be used as a platform technology for intracellular delivery of siRNAs to NTSR1
Cyclic saturation behavior of tungsten monofilament-reinforced monocrystalline copper matrix composites

International Nuclear Information System (INIS)

Zhang, J.; Laird, C.

1999-01-01

Studies on saturation behavior produced by cyclic deformation have been conducted on tungsten monofilament-reinforced monocrystalline copper composites. The effect of the fiber on strain localization has been investigated using interferometry. For a given applied strain amplitude, local strain and volume fraction of the persistent slip bands (PSBs) in the composite appeared no different from those observed in monolithic copper single crystals. However, the distribution of the PSBs was observed to be more uniform, and the total number of PSBs is substantially higher than that in monolithic crystals. The PSBs appeared mostly in the form of micro-PSBs or macro-PSBs with very limited width. Instead of expanding existing PSBs, new PSBs were more likely to nucleate at new locations during cyclic deformation. The volume fraction and width of the PSBs were observed to increase during saturation, which indicates that some of the PSBs become aged and new PSBs form in order to continue to carry the plastic strain. A rule of mixtures model was established to link the cyclic stress-strain response of the monocrystalline composites to the behavior of monolithic single crystals and fibers. The results calculated from the model show very good agreement with the experimental data
Fluorescence imaging as a diagnostic of M-band x-ray drive condition in hohlraum with fluorescent Si targets

International Nuclear Information System (INIS)

Li, Qi; Hu, Zhimin; Yao, Li; Huang, Chengwu; Yuan, Zheng; Zhao, Yang; Xiong, Gang; Qing, Bo; Lv, Min; Zhu, Tuo; Deng, Bo; Li, Jin; Wei, Minxi; Zhan, Xiayu; Li, Jun; Yang, Yimeng; Su, Chunxiao; Yang, Guohong; Zhang, Jiyan; Li, Sanwei

2017-01-01

Fluorescence imaging of surrogate Si-doped CH targets has been used to provide a measurement for drive condition of high-energy x-ray (i.e. M-band x-ray) drive symmetry upon the capsule in hohlraum on Shenguang-II laser facility. A series of experiments dedicated to the study of photo-pumping and fluorescence effect in Si-plasma are presented. To investigate the feasibility of fluorescence imaging in Si-plasma, an silicon plasma in Si-foil target is pre-formed at ground state by the soft x-ray from a half-hohlraum, which is then photo-pumped by the K-shell lines from a spatially distinct laser-produced Si-plasma. The resonant Si photon pump is used to improve the fluorescence signal and cause visible image in the Si-foil. Preliminary fluorescence imaging of Si-ball target is performed in both Si-doped and pure Au hohlraum. The usual capsule at the center of the hohlraum is replaced with a solid Si-doped CH-ball (Si-ball). Since the fluorescence is proportional to the photon pump upon the Si-plasma, high-energy x-ray drive symmetry is equal to the fluorescence distribution of the Si-ball. (paper)
In Silico Design and Experimental Validation of siRNAs Targeting Conserved Regions of Multiple Hepatitis C Virus Genotypes.

Directory of Open Access Journals (Sweden)

Mahmoud ElHefnawi

Full Text Available RNA interference (RNAi is a post-transcriptional gene silencing mechanism that mediates the sequence-specific degradation of targeted RNA and thus provides a tremendous opportunity for development of oligonucleotide-based drugs. Here, we report on the design and validation of small interfering RNAs (siRNAs targeting highly conserved regions of the hepatitis C virus (HCV genome. To aim for therapeutic applications by optimizing the RNAi efficacy and reducing potential side effects, we considered different factors such as target RNA variations, thermodynamics and accessibility of the siRNA and target RNA, and off-target effects. This aim was achieved using an in silico design and selection protocol complemented by an automated MysiRNA-Designer pipeline. The protocol included the design and filtration of siRNAs targeting highly conserved and accessible regions within the HCV internal ribosome entry site, and adjacent core sequences of the viral genome with high-ranking efficacy scores. Off-target analysis excluded siRNAs with potential binding to human mRNAs. Under this strict selection process, two siRNAs (HCV353 and HCV258 were selected based on their predicted high specificity and potency. These siRNAs were tested for antiviral efficacy in HCV genotype 1 and 2 replicon cell lines. Both in silico-designed siRNAs efficiently inhibited HCV RNA replication, even at low concentrations and for short exposure times (24h; they also exceeded the antiviral potencies of reference siRNAs targeting HCV. Furthermore, HCV353 and HCV258 siRNAs also inhibited replication of patient-derived HCV genotype 4 isolates in infected Huh-7 cells. Prolonged treatment of HCV replicon cells with HCV353 did not result in the appearance of escape mutant viruses. Taken together, these results reveal the accuracy and strength of our integrated siRNA design and selection protocols. These protocols could be used to design highly potent and specific RNAi-based therapeutic
Large three-dimensional photonic crystals based on monocrystalline liquid crystal blue phases.

Science.gov (United States)

Chen, Chun-Wei; Hou, Chien-Tsung; Li, Cheng-Chang; Jau, Hung-Chang; Wang, Chun-Ta; Hong, Ching-Lang; Guo, Duan-Yi; Wang, Cheng-Yu; Chiang, Sheng-Ping; Bunning, Timothy J; Khoo, Iam-Choon; Lin, Tsung-Hsien

2017-09-28

Although there have been intense efforts to fabricate large three-dimensional photonic crystals in order to realize their full potential, the technologies developed so far are still beset with various material processing and cost issues. Conventional top-down fabrications are costly and time-consuming, whereas natural self-assembly and bottom-up fabrications often result in high defect density and limited dimensions. Here we report the fabrication of extraordinarily large monocrystalline photonic crystals by controlling the self-assembly processes which occur in unique phases of liquid crystals that exhibit three-dimensional photonic-crystalline properties called liquid-crystal blue phases. In particular, we have developed a gradient-temperature technique that enables three-dimensional photonic crystals to grow to lateral dimensions of ~1 cm (~30,000 of unit cells) and thickness of ~100 μm (~ 300 unit cells). These giant single crystals exhibit extraordinarily sharp photonic bandgaps with high reflectivity, long-range periodicity in all dimensions and well-defined lattice orientation.Conventional fabrication approaches for large-size three-dimensional photonic crystals are problematic. By properly controlling the self-assembly processes, the authors report the fabrication of monocrystalline blue phase liquid crystals that exhibit three-dimensional photonic-crystalline properties.
Efficient VEGF targeting delivery of DOX using Bevacizumab conjugated SiO2@LDH for anti-neuroblastoma therapy.

Science.gov (United States)

Zhu, Rongrong; Wang, Zhaoqi; Liang, Peng; He, Xiaolie; Zhuang, Xizhen; Huang, Ruiqi; Wang, Mei; Wang, Qigang; Qian, Yechang; Wang, Shilong

2017-11-01

Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis and is highly expressed in carcinoma, which make it an important target for tumor targeting therapy. Neuroblastoma is the main cause for cancer-related death in children. Like most solid tumors, it is also accompanied with the overexpression of VEGF. Doxorubicin Hydrochloride (DOX), a typical chemotherapeutic agent, exhibits efficient anticancer activities for various cancers. However, DOX, without targeting ability, usually causes severe damage to normal tissues. To overcome the shortages, we designed a novel nano-composite, which is Bevacizumab (Bev) modified SiO 2 @LDH nanoparticles (SiO 2 @LDH-Bev), loading with DOX to achieve targeting ability and curative efficiency. SiO 2 @LDH-DOX and SiO 2 @LDH-Bev-DOX nanoparticles were synthesized and the physicochemical properties were characterized by TEM detection, Zeta potential analysis, FTIR, Raman and XPS analysis. Then in vitro and in vivo anti-neuroblastoma efficiency, targeting ability and mechanisms of anti-carcinoma and anti-angiogenesis of SiO 2 @LDH-Bev-DOX were explored. Our results indicated that we obtained the core-shell structure SiO 2 @LDH-Bev with an average diameter of 253±10nm and the amount of conjugated Bev was 4.59±0.38μg/mg SiO 2 @LDH-Bev. SiO 2 @LDH-Bev-DOX could improve the cellular uptake and the targeting effect of DOX to brain and tumor, enhance the anti-neuroblastoma and anti-angiogenesis efficiency both in vitro and in vivo, and alleviate side effects of DOX sharply, especially hepatic injury. In addition, we also demonstrated that angiogenesis inhibitory effect was mediated by DOX and VEGF triggered signal pathways, including PI3K/Akt, Raf/MEK/ERK, and adhesion related pathways. In summary, SiO 2 @LDH-Bev could be a potential VEGF targeting nanocarrier applied in VEGF positive cancer therapy. This paper explored that a novel core-shell structure nanomaterial SiO 2 @LDH and modified SiO 2 @LDH with
Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

Directory of Open Access Journals (Sweden)

Mohamed T. Ghoneim

2015-12-01

Full Text Available In today’s digital world, complementary metal oxide semiconductor (CMOS technology enabled scaling of bulk mono-crystalline silicon (100 based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm mono-crystalline (100 silicon (detached from bulk substrate by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs with high-κ/metal gate stacks.
Monocrystalline fibres for low thermal noise suspension in advanced gravitational wave detectors

International Nuclear Information System (INIS)

Amico, P; Bosi, L; Gammaitoni, L; Losurdo, G; Marchesoni, F; Mazzoni, M; Parisi, D; Punturo, M; Stanga, R; Toncelli, A; Tonelli, M; Travasso, F; Vetrano, F; Vocca, H

2004-01-01

Thermal noise in mirror suspension will be the most severe fundamental limit to the low-frequency sensitivity of future interferometric gravitational wave detectors. We propose a new type of materials to realize low thermal noise suspension in such detectors. Monocrystalline suspension fibres are good candidates both for cryogenic and for ambient temperature interferometers. Material characteristics and a production facility are described in this paper
Monocrystalline fibres for low thermal noise suspension in advanced gravitational wave detectors

Energy Technology Data Exchange (ETDEWEB)

Amico, P [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Bosi, L [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Gammaitoni, L [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Losurdo, G [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Marchesoni, F [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Mazzoni, M [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Parisi, D [NEST-Dipartimento di Fisica, Universita di Pisa, Pisa (Italy); Punturo, M [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Stanga, R [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Toncelli, A [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Pisa (Italy); Tonelli, M [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Pisa (Italy); Travasso, F [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy); Vetrano, F [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze/Urbino, Florence (Italy); Vocca, H [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Virgo Project, I-06100 Perugia (Italy)

2004-03-07

Thermal noise in mirror suspension will be the most severe fundamental limit to the low-frequency sensitivity of future interferometric gravitational wave detectors. We propose a new type of materials to realize low thermal noise suspension in such detectors. Monocrystalline suspension fibres are good candidates both for cryogenic and for ambient temperature interferometers. Material characteristics and a production facility are described in this paper.
Novel targets for sensitizing breast cancer cells to TRAIL-induced apoptosis with siRNA delivery.

Science.gov (United States)

Thapa, Bindu; Bahadur Kc, Remant; Uludağ, Hasan

2018-02-01

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in variety of cancer cells without affecting most normal cells, which makes it a promising agent for cancer therapy. However, TRAIL therapy is clinically not effective due to resistance induction. To identify novel regulators of TRAIL that can aid in therapy, protein targets whose silencing sensitized breast cancer cells against TRAIL were screened with an siRNA library against 446 human apoptosis-related proteins in MDA-231 cells. Using a cationic lipopolymer (PEI-αLA) for delivery of library members, 16 siRNAs were identified that sensitized the TRAIL-induced death in MDA-231 cells. The siRNAs targeting BCL2L12 and SOD1 were further evaluated based on the novelty and their ability to sensitize TRAIL induced cell death. Silencing both targets sensitized TRAIL-mediated cell death in MDA-231 cells as well as TRAIL resistant breast cancer cells, MCF-7. Combination of TRAIL and siRNA silencing BCL2L12 had no effect in normal human umbilical vein cells and human bone marrow stromal cell. The silencing of BCL2L12 and SOD1 enhanced TRAIL-mediated apoptosis in MDA-231 cells via synergistically activating capsase-3 activity. Hence, here we report siRNAs targeting BCL2L12 and SOD1 as a novel regulator of TRAIL-induced cell death in breast cancer cells, providing a new approach for enhancing TRAIL therapy for breast cancer. The combination of siRNA targeting BCL2L12 and TRAIL can be a highly effective synergistic pair in breast cancer cells with minimal effect on the non-transformed cells. © 2017 UICC.
High quality β-FeSi2 thin films prepared on silicon (100) by using pulsed laser ablation of Fe target

International Nuclear Information System (INIS)

Xu, S.C.; Yang, C.; Liu, M.; Jiang, S.Z.; Ma, Y.Y.; Chen, C.S.; Gao, X.G.; Sun, Z.C.; Hu, B.; Wang, C.C.; Man, B.Y.

2012-01-01

High quality β-FeSi 2 thin films have been fabricated on silicon (100) substrate by the pulsed laser deposition (PLD) technique with the Fe and sintered FeSi 2 targets. The crystalline quality and surface morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. These results indicate that the samples prepared with a Fe target can acquire a better crystalline quality and a smoother surface than those with a sintered FeSi 2 target. The reasons were discussed with subsurface superheating mechanism. The intrinsic PL spectrum attributed to the interband transition of β-FeSi 2 for all the samples was compared, showing that the film prepared with Fe target can acquire a good PL property by optimizing experimental parameters. It is suggested that sputtering Fe on Si substrate by the pulsed laser offers a cheap and convenient way to prepare the β-FeSi 2 thin films. -- Highlights: ► β-FeSi 2 films were fabricated by PLD technique with the Fe and FeSi 2 targets. ► The films prepared with Fe target have good crystalline quality and smooth surface. ► The Fe target prepared film acquired a high PL intensity. ► Sputtering Fe on Si substrate offers a convenient way to prepare the β-FeSi 2 films.
Low-temperature internal friction in high-purity monocrystalline and impure polycrystalline niobium after plastic deformation

International Nuclear Information System (INIS)

Wasserbaech, W.; Thompson, E.

2001-01-01

The internal friction Q -1 of plastically deformed, high-purity monocrystalline and impure polycrystalline niobium specimens was measured in the temperature range between 65 mK and about 2 K. Plastic deformation has a pronounced effect on the internal friction Q -1 of the high-purity monocrystalline specimens, and the effect has been found to be almost temperature independent. By contrast, surprisingly, the internal friction Q -1 of the impure polycrystalline specimens was found to be almost independent of the extent of plastic deformation. Comparison of the experimental results with different models of a dynamic scattering of acoustic phonons by dislocations leads to the conclusion that the results cannot be explained with the two-level tunneling model. Instead it is suggested that a strong interaction between acoustic phonons and geometrical kinks in non-screw dislocations is responsible for the observed internal friction Q -1 . (orig.)
An effective tumor-targeting strategy utilizing hypoxia-sensitive siRNA delivery system for improved anti-tumor outcome.

Science.gov (United States)

Kang, Lin; Fan, Bo; Sun, Ping; Huang, Wei; Jin, Mingji; Wang, Qiming; Gao, Zhonggao

2016-10-15

Hypoxia is a feature of most solid tumors, targeting hypoxia is considered as the best validated yet not extensively exploited strategy in cancer therapy. Here, we reported a novel tumor-targeting strategy using a hypoxia-sensitive siRNA delivery system. In the study, 2-nitroimidazole (NI), a hydrophobic component that can be converted to hydrophilic 2-aminoimidazole (AI) through bioreduction under hypoxic conditions, was conjugated to the alkylated polyethyleneimine (bPEI1.8k-C6) to form amphiphilic bPEI1.8k-C6-NI polycations. bPEI1.8k-C6-NI could self-assemble into micelle-like aggregations in aqueous, which contributed to the improved stability of the bPEI1.8k-C6-NI/siRNA polyplexes, resulted in increased cellular uptake. After being transported into the hypoxic tumor cells, the selective nitro-to-amino reduction would cause structural change and elicit a relatively loose structure to facilitate the siRNA dissociation in the cytoplasm, for enhanced gene silencing efficiency ultimately. Therefore, the conflict between the extracellular stability and the intracellular siRNA release ability of the polyplexes was solved by introducing the hypoxia-responsive unit. Consequently, the survivin-targeted siRNA loaded polyplexes shown remarkable anti-tumor effect not only in hypoxic cells, but also in tumor spheroids and tumor-bearing mice, indicating that the hypoxia-sensitive siRNA delivery system had great potential for tumor-targeted therapy. Hypoxia is one of the most remarkable features of most solid tumors, and targeting hypoxia is considered as the best validated strategy in cancer therapy. However, in the past decades, there were few reports about using this strategy in the drug delivery system, especially in siRNA delivery system. Therefore, we constructed a hypoxia-sensitive siRNA delivery system utilizing a hypoxia-responsive unit, 2-nitroimidazole, by which the unavoidable conflict between improved extracellular stability and promoted intracellular si
Rational design of micro-RNA-like bifunctional siRNAs targeting HIV and the HIV coreceptor CCR5.

Science.gov (United States)

Ehsani, Ali; Saetrom, Pål; Zhang, Jane; Alluin, Jessica; Li, Haitang; Snøve, Ola; Aagaard, Lars; Rossi, John J

2010-04-01

Small-interfering RNAs (siRNAs) and micro-RNAs (miRNAs) are distinguished by their modes of action. SiRNAs serve as guides for sequence-specific cleavage of complementary mRNAs and the targets can be in coding or noncoding regions of the target transcripts. MiRNAs inhibit translation via partially complementary base-pairing to 3' untranslated regions (UTRs) and are generally ineffective when targeting coding regions of a transcript. In this study, we deliberately designed siRNAs that simultaneously direct cleavage and translational suppression of HIV RNAs, or cleavage of the mRNA encoding the HIV coreceptor CCR5 and suppression of translation of HIV. These bifunctional siRNAs trigger inhibition of HIV infection and replication in cell culture. The design principles have wide applications throughout the genome, as about 90% of genes harbor sites that make the design of bifunctional siRNAs possible.
Direct Current Sputter Epitaxy of Heavily Doped p+ Layer for Monocrystalline Si Solar Cells

Directory of Open Access Journals (Sweden)

Wenchang Yeh

2017-01-01

Full Text Available Sputter epitaxy of p+ layer for fabrication of Si solar cells (SCs was demonstrated. Hall carrier concentration of p+ layer was 2.6 × 1020 cm−3 owing to cosputtering of B with Si at low temperature, which had enabled heavy and shallow p+ dope layer. p+nn+ SCs were fabricated and influence of p+ and n+ layers was investigated. Internal quantum efficiency (IQE of p+nn+ SCs was 95% at visible light and was larger than 60% at ultraviolet (UV light when the p+ layer was thinner than 30 nm. At near infrared (NIR, extra increment on IQE was achieved by rear n+ back surface field (BSF layer with a thickness thinner than 100 nm.
Novel targeted therapy for neuroblastoma: silencing the MXD3 gene using siRNA.

Science.gov (United States)

Duong, Connie; Yoshida, Sakiko; Chen, Cathy; Barisone, Gustavo; Diaz, Elva; Li, Yueju; Beckett, Laurel; Chung, Jong; Antony, Reuben; Nolta, Jan; Nitin, Nitin; Satake, Noriko

2017-09-01

BackgroundNeuroblastoma is the second most common extracranial cancer in children. Current therapies for neuroblastoma, which use a combination of chemotherapy drugs, have limitations for high-risk subtypes and can cause significant long-term adverse effects in young patients. Therefore, a new therapy is needed. In this study, we investigated the transcription factor MXD3 as a potential therapeutic target in neuroblastoma.MethodsMXD3 expression was analyzed in five neuroblastoma cell lines by immunocytochemistry and quantitative real-time reverse transcription PCR, and in 18 primary patient tumor samples by immunohistochemistry. We developed nanocomplexes using siRNA and superparamagnetic iron oxide nanoparticles to target MXD3 in neuroblastoma cell lines in vitro as a single-agent therapeutic and in combination with doxorubicin, vincristine, cisplatin, or maphosphamide-common drugs used in current neuroblastoma treatment.ResultsMXD3 was highly expressed in neuroblastoma cell lines and in patient tumors that had high-risk features. Neuroblastoma cells treated in vitro with the MXD3 siRNA nanocomplexes showed MXD3 protein knockdown and resulted in cell apoptosis. Furthermore, on combining MXD3 siRNA nanocomplexes with each of the four drugs, all showed additive efficacy.ConclusionThese results indicate that MXD3 is a potential new target and that the use of MXD3 siRNA nanocomplexes is a novel therapeutic approach for neuroblastoma.
Receptor-targeted liposome-peptide-siRNA nanoparticles represent an efficient delivery system for MRTF silencing in conjunctival fibrosis.

Science.gov (United States)

Yu-Wai-Man, Cynthia; Tagalakis, Aristides D; Manunta, Maria D; Hart, Stephen L; Khaw, Peng T

2016-02-24

There is increasing evidence that the Myocardin-related transcription factor/Serum response factor (MRTF/SRF) pathway plays a key role in fibroblast activation and that knocking down MRTF can lead to reduced scarring and fibrosis. Here, we have developed a receptor-targeted liposome-peptide-siRNA nanoparticle as a non-viral delivery system for MRTF-B siRNA in conjunctival fibrosis. Using 50 nM siRNA, the MRTF-B gene was efficiently silenced by 76% and 72% with LYR and LER nanoparticles, respectively. The silencing efficiency was low when non-targeting peptides or siRNA alone or liposome-siRNA alone were used. LYR and LER nanoparticles also showed higher silencing efficiency than PEGylated LYR-P and LER-P nanoparticles. The nanoparticles were not cytotoxic using different liposomes, targeting peptides, and 50 nM siRNA. Three-dimensional fibroblast-populated collagen matrices were also used as a functional assay to measure contraction in vitro, and showed that MRTF-B LYR nanoparticles completely blocked matrix contraction after a single transfection treatment. In conclusion, this is the first study to develop and show that receptor-targeted liposome-peptide-siRNA nanoparticles represent an efficient and safe non-viral siRNA delivery system that could be used to prevent fibrosis after glaucoma filtration surgery and other contractile scarring conditions in the eye.
siRNA as a tool to improve the treatment of brain diseases: Mechanism, targets and delivery.

Science.gov (United States)

Gomes, Maria João; Martins, Susana; Sarmento, Bruno

2015-05-01

As the population ages, brain pathologies such as neurodegenerative diseases and brain cancer increase their incidence, being the need to find successful treatments of upmost importance. Drug delivery to the central nervous system (CNS) is required in order to reach diseases causes and treat them. However, biological barriers, mainly blood-brain barrier (BBB), are the key obstacles that prevent the effectiveness of possible treatments due to their ability to strongly limit the perfusion of compounds into the brain. Over the past decades, new approaches towards overcoming BBB and its efflux transporters had been proposed. One of these approaches here reviewed is through small interfering RNA (siRNA), which is capable to specifically target one gene and silence it in a post-transcriptional way. There are different possible functional proteins at the BBB, as the ones responsible for transport or just for its tightness, which could be a siRNA target. As important as the effective silence is the way to delivery siRNA to its anatomical site of action. This is where nanotechnology-based systems may help, by protecting siRNA circulation and providing cell/tissue-targeting and intracellular siRNA delivery. After an initial overview on incidence of brain diseases and basic features of the CNS, BBB and its efflux pumps, this review focuses on recent strategies to reach brain based on siRNA, and how to specifically target these approaches in order to treat brain diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of Si(1 1 1) crystals implanted with Sb{sup +} ions and annealed by rapid thermal processing

Energy Technology Data Exchange (ETDEWEB)

Labbani, R.; Halimi, R.; Laoui, T.; Vantomme, A.; Pipeleers, B.; Roebben, G

2003-09-15

Monocrystalline Si(1 1 1) targets are implanted (at room temperature) with antimony ions at 120 keV energy to 5x10{sup 14} or 5x10{sup 15} Sb{sup +} cm{sup -2} dose. The samples are heat treated by means of rapid thermal processing (RTP) at 1000 deg. C during 60 s, under nitrogen atmosphere. In this work, we report the measured evolution of the silicon surface damage and the radiation damage recovery in relation to antimony dose and RTP processing. We also study the behavior of antimony dopant into Si(1 1 1) specimens. The investigation is carried out by He{sup +} Rutherford backscattering spectrometry (RBS; operating at 1.57 MeV energy in both random and channeling modes), X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. It is shown that a good surface damage recovery is obtained for all the annealed samples. However, after RTP, a significant loss of antimony has occurred for the specimens which are implanted with 5x10{sup 15} Sb{sup +} cm{sup -2} dose. This suggests an antimony out-diffusion. Finally, a good morphological characterization of the specimens is provided by AFM.
Deposition of copper coatings in a magnetron with liquid target

Energy Technology Data Exchange (ETDEWEB)

Tumarkin, A. V., E-mail: sanyahrustal@mail.ru; Kaziev, A. V.; Kolodko, D. V.; Pisarev, A. A.; Kharkov, M. M.; Khodachenko, G. V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)

2015-12-15

Copper coatings were deposited on monocrystalline Si substrates using a magnetron discharge with a liquid cathode in the metal vapour plasma. During the deposition, the bias voltage in the range from 0 V to–400 V was applied to the substrate. The prepared films were investigated by a scanning electron microscope, and their adhesive properties were studied using a scratch tester. It was demonstrated that the adhesion of the deposited films strongly depends on the bias voltage and varies in a wide range.
Local field in LiD polarized target material

CERN Document Server

Kisselev, Yu V; Baum, G; Berglund, P; Doshita, N; Gautheron, F; Görtz, S; Horikawa, N; Koivuniemi, J H; Kondo, K; Magnon, A; Meyer, Werner T; Reicherz, G

2004-01-01

We have experimentally studied the first and the second moments of D, **6Li and **7Li (I greater than 1/2) NMR lines in a granulated LiD- target material as a function of nuclear polarizations and the data has been compared with a theory elaborated by Abragam, Roinel and Bouffard for monocrystalline samples. The experiments were carried out in the large COMPASS twin-target at CERN. The static local magnetic field of the polarized nuclei was measured by frequency shift between the NMR-signals in the two oppositely polarized cells and lead to the first moment, whereas the investigation of the second moment was done through Gaussian approximation. The average field magnitude in granulated material was estimated 20% larger than the value given by the calculations for monocrystalline samples of cylindrical shape. The second moment shows a qualitative agreement with the theory but it is slightly larger at the negative than at the positive polarization. In a polarized mode, the moments depend on the saturated microw...
Delivery of kinesin spindle protein targeting siRNA in solid lipid nanoparticles to cellular models of tumor vasculature

International Nuclear Information System (INIS)

Ying, Bo; Campbell, Robert B.

2014-01-01

Highlights: • siRNA-lipid nanoparticles are solid particles not lipid bilayers with aqueous core. • High, but not low, PEG content can prevent nanoparticle encapsulation of siRNA. • PEG reduces cellular toxicity of cationic nanoparticles in vitro. • PEG reduces zeta potential while improving gene silencing of siRNA nanoparticles. • Kinesin spindle protein can be an effective target for tumor vascular targeting. - Abstract: The ideal siRNA delivery system should selectively deliver the construct to the target cell, avoid enzymatic degradation, and evade uptake by phagocytes. In the present study, we evaluated the importance of polyethylene glycol (PEG) on lipid-based carrier systems for encapsulating, and delivering, siRNA to tumor vessels using cellular models. Lipid nanoparticles containing different percentage of PEG were evaluated based on their physical chemical properties, density compared to water, siRNA encapsulation, toxicity, targeting efficiency and gene silencing in vitro. siRNA can be efficiently loaded into lipid nanoparticles (LNPs) when DOTAP is included in the formulation mixture. However, the total amount encapsulated decreased with increase in PEG content. In the presence of siRNA, the final formulations contained a mixed population of particles based on density. The major population which contains the majority of siRNA exhibited a density of 4% glucose, and the minor fraction associated with a decreased amount of siRNA had a density less than PBS. The inclusion of 10 mol% PEG resulted in a greater amount of siRNA associated with the minor fraction. Finally, when kinesin spindle protein (KSP) siRNA was encapsulated in lipid nanoparticles containing a modest amount of PEG, the proliferation of endothelial cells was inhibited due to the efficient knock down of KSP mRNA. The presence of siRNA resulted in the formation of solid lipid nanoparticles when prepared using the thin film and hydration method. LNPs with a relatively modest amount of
Influence of Material Coating on the Heat Transfer in a Layered Cu-SiC-Cu Systems

Directory of Open Access Journals (Sweden)

Strojny-Nędza A.

2017-06-01

Full Text Available This paper describes the process of obtaining Cu-SiC-Cu systems by way of spark plasma sintering. A monocrystalline form of silicon carbide (6H-SiC type was applied in the experiment. Additionally, silicon carbide samples were covered with a layer of tungsten and molybdenum using chemical vapour deposition (CVD technique. Microstructural examinations and thermal properties measurements were performed. A special attention was put to the metal-ceramic interface. During annealing at a high temperature, copper reacts with silicon carbide. To prevent the decomposition of silicon carbide two types of coating (tungsten and molybdenum were applied. The effect of covering SiC with the aforementioned elements on the composite’s thermal conductivity was analyzed. Results were compared with the numerical modelling of heat transfer in Cu-SiC-Cu systems. Certain possible reasons behind differences in measurements and modelling results were discussed.
Synthetic siRNAs effectively target cystein protease 12 and α-actinin transcripts in Trichomonas vaginalis.

Science.gov (United States)

Ravaee, Roya; Ebadi, Parimah; Hatam, Gholamreza; Vafafar, Arghavan; Ghahramani Seno, Mohammad Mahdi

2015-10-01

The flagellated protozoan Trichomonas vaginalis (T. vaginalis) causes trichomoniasis, a reproductive tract infection, in humans. Trichomoniasis is the most common non-viral sexually transmitted disease worldwide. In addition to direct consequences such as infertility and abortion, there are indications that trichomoniasis favours development of prostate cancer and it has also been associated with increased risk of spreading human immunodeficiency virus and papillomavirus infections. Reports from around the world show that the rate of drug resistance in T. vaginalis is increasing, and therefore new therapeutic approaches have to be developed. Studying molecular biology of T. vaginalis will be quite helpful in identifying new drugable targets. RNAi is a powerful technique which allows biologist to specifically target gene products (i.e. mRNA) helping them in unravelling gene functions and biology of systems. However, due to lack of some parts of the required intrinsic RNAi machinery, the RNAi system is not functional in all orders of life. Here, by using synthetic siRNAs targeting two genes, i.e. α-actinin and cystein protease 12 (cp12), we demonstrate T. vaginalis cells are amenable to RNAi experiments conducted by extrinsic siRNAs. Electroporation of siRNAs targeting α-actinin or cp12 into T. vaginalis cells resulted in, respectively, 48-67% and 33-72% downregulation of the cognate transcripts compared to the T. vaginalis cells received siRNAs targeting GL2 luciferase as a control. This finding is helpful in that it demonstrates the potential of using extrinsically induced RNAi in studies on molecular biology of T. vaginalis such as those aiming at identifying new drug targets. Copyright © 2015 Elsevier Inc. All rights reserved.
Elaboration of a semiconductive thin film device technology on the basis of monocrystalline gallium arsenide

International Nuclear Information System (INIS)

Antoshenko, V.; Taurbaev, T.; Skirnevskaya, E.; Shorin, V.; Mihajlov, L.; Bajganatova, Sh.

1996-01-01

The aim of the project: To elaborate the economical technological process of preparing super thin monocrystalline GaAs substrates and device structures for semiconductive electronics. To realize the project it is necessary to solve following problems: o to elaborate and produce the equipment for preparing of separated films and thin film multilayer structures with p-n-junction; - to study conditions of preparing plane crystal perfect separated Ga(Al)As - films; - to optimize regimes of preparing thin film structures with p- and n-conductive - layers; - to determine the optimal methods of transferring autonomous films and structures over the second substrates; - to work out preparing methods of ohmic contacts and electrical commutation; - to optimize the process of repeated use of initial monocrystalline GaAs substrate; - to prepare the samples of discrete thin film photo- and emitting devices. As the result of project realization there will be created cheap ecological technology of heterojunction optoelectronic devices on the basis of GaAs and AlGaAs solid solutions, the laboratory samples of thin film devices will be presented
siRNAs targeting PB2 and NP genes potentially inhibit replication

Indian Academy of Sciences (India)

% and has caused the death or culling of millions of poultry since 2003. In this study, we have designed three siRNAs (PB2-2235, PB2-479 and NP-865) targeting PB2 and NP genes of avian influenza virus and evaluated their potential, ...
Target swapping in PLD: An efficient approach for CdS/SiO2 and CdS:Ag(1%)/SiO2 nanocomposite thin films with enhanced luminescent properties

International Nuclear Information System (INIS)

Saxena, Nupur; Kumar, Pragati; Gupta, Vinay

2017-01-01

A novel synthesis method for luminescent and by-products (like CdO) free CdS/SiO 2 and CdS:Ag(1%)/SiO 2 (i.e. 1%Ag doped CdS/SiO 2 ) nanocomposite thin films at room temperature by pulsed laser deposition is reported. Targets of CdS, CdS:Ag(1%) and SiO 2 are used to deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposite thin films by swapping them at a frequency ratio of 2:8 laser pulses/sec. X-ray photoelectron spectroscopy analysis ensures the ratio of CdS to SiO 2 in nanocomposite as 21:79 which is nearly same as the ratio of incident pulses/sec (i.e. 2:8) on the two targets. Transmission electron micrographs visualize the formation of CdS/ CdS:Ag(1%) nanocrystals in nanocomposite systems after annealing at 500 °C. Highly intense and broad red emission is achieved from CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposites. The efficiencies of emission from pristine CdS:SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposites are found to be enhanced by approximately two times as compared to sole nanocrystalline CdS and CdS:Ag(1%) thin films respectively and further enhanced upto 7 times on annealing the nanocomposite systems at 500 °C. - Graphical abstract: A modified synthesis method for luminescent and by-products (like CdO) free undoped &1% Ag doped CdS/SiO 2 (deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 ) nanocomposite thin films at room temperature by pulsed laser deposition is reported. Targets of CdS or CdS:Ag(1%) and SiO 2 are used to deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposite thin films by swapping them at a frequency of 2:8 pulses/sec. X-ray photoelectron spectroscopy analysis ensures the ratio of CdS to SiO 2 in nanocomposite as 21:79 which is nearly same as the ratio of incident pulses/sec (2:8) on the two targets. Transmission electron micrographs visualize the formation of CdS nanocrystals in nanocomposite systems after annealing at 500 °C. Intense and broad red emission is achieved from deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposites. The efficiency of
Novel functionalized nanoparticles for tumor-targeting co-delivery of doxorubicin and siRNA to enhance cancer therapy

Directory of Open Access Journals (Sweden)

Xia Y

2017-12-01

Full Text Available Yu Xia, Tiantian Xu, Changbing Wang, Yinghua Li, Zhengfang Lin, Mingqi Zhao, Bing Zhu Central Laboratory, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, People’s Republic of China Abstract: Human homeobox protein (Nanog is highly expressed in most cancer cells and has gradually emerged as an excellent target in cancer therapy, owing to its regulation of cancer cell proliferation, metastasis and apoptosis. In this study, we prepared tumor-targeting functionalized selenium nanoparticles (RGDfC-SeNPs to load chemotherapeutic doxorubicin (DOX and Nanog siRNA. Herein, RGDfC peptide was used as a tumor-targeting moiety which could specifically bind to αvβ3 integrins overexpressed on various cancer cells. The sizes of RGDfC-SeNPs@DOX nanoparticles (~12 nm were confirmed by both dynamic light scattering and transmission electron microscopy. The chemical structure of RGDfC-SeNPs@DOX was characterized via Fourier-transform infrared spectroscopy. The RGDfC-SeNPs@DOX was compacted with siRNA (anti-Nanog by electrostatic interaction to fabricate the RGDfC-SeNPs@DOX/siRNA complex. The RGDfC-SeNPs@DOX/siRNA complex nanoparticles could efficiently enter into HepG2 cells via clathrin-associated endocytosis, and showed high gene transfection efficiency that resulted in enhanced gene silencing. The in vivo biodistribution experiment indicated that RGDfC-SeNPs@DOX/siRNA nanoparticles were capable of specifically accumulating in the tumor site. Furthermore, treatment with RGDfC-SeNPs@DOX/siRNA resulted in a more significant anticancer activity than the free DOX, RGDfC-SeNPs@DOX or RGDfC-SeNPs/siRNA in vitro and in vivo. In summary, this study shows a novel type of DOX and siRNA co-delivery system, thereby providing an alternative route for cancer treatment. Keywords: nanoparticles, tumor targeting, drug delivery, doxorubicin, Nanog siRNA
An ABA-responsive DRE-binding protein gene from Setaria italica, SiARDP, the target gene of SiAREB, plays a critical role under drought stress.

Science.gov (United States)

Li, Cong; Yue, Jing; Wu, Xiaowei; Xu, Cong; Yu, Jingjuan

2014-10-01

The DREB (dehydration-responsive element binding)-type transcription factors regulate the expression of stress-inducible genes by binding the DRE/CRT cis-elements in promoter regions. The upstream transcription factors that regulate the transcription of DREB transcription factors have not been clearly defined, although the function of DREB transcription factors in abiotic stress is known. In this study, an abscisic acid (ABA)-responsive DREB-binding protein gene (SiARDP) was cloned from foxtail millet (Setaria italica). The transcript level of SiARDP increased not only after drought, high salt, and low temperature stresses, but also after an ABA treatment in foxtail millet seedlings. Two ABA-responsive elements (ABRE1: ACGTGTC; ABRE2: ACGTGGC) exist in the promoter of SiARDP. Further analyses showed that two ABA-responsive element binding (AREB)-type transcription factors, SiAREB1 and SiAREB2, could physically bind to the ABRE core element in vitro and in vivo. The constitutive expression of SiARDP in Arabidopsis thaliana enhanced drought and salt tolerance during seed germination and seedling development, and overexpression of SiARDP in foxtail millet improved drought tolerance. The expression levels of target genes of SiARDP were upregulated in transgenic Arabidopsis and foxtail millet. These results reveal that SiARDP, one of the target genes of SiAREB, is involved in ABA-dependent signal pathways and plays a critical role in the abiotic stress response in plants. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.
Characterization and vectorization of siRNA targeting RET/PTC1 in human papillary thyroid carcinoma cells

Directory of Open Access Journals (Sweden)

Massade L.

2011-10-01

Full Text Available RET/PTC1 fusion oncogene is the most common genetic alteration identified to date in thyroid papillary carcinomas (PTC and represents a good target for small interfering RNA (siRNA. Our aim was: i to target the RET/PTC1 oncogene by siRNAs, ii to assess the knockdown effects on cell growth and cell cycle regulation and iii to vectorize it in order to protect it from degradation. Methods. Human cell lines expressing RET/PTC1 were transfected by siRNA RET/PTC1, inhibition of the oncogene expression was assessed by qRT-PCR and by Western blot. Conjugation of siRNA RET/PTC1 to squalene was performed by coupling it to squalene. In vivo studies are performed in nude mice. Conclusion. In this short communication, we report the main published results obtained during last years.
A Power Case Study for Monocrystalline and Polycrystalline Solar Panels in Bursa City, Turkey

OpenAIRE

Taşçıoğlu, Ayşegül; Taşkın, Onur; Vardar, Ali

2016-01-01

It was intended to reveal the time dependent power generation under different loads for two different solar panels under the conditions of Bursa province in between August 19 and 25, 2014. The testing sets include solar panels, inverter, multimeter, accumulator, regulator, pyranometer, pyrheliometer, temperature sensor, and datalogger. The efficiency of monocrystalline and polycrystalline solar panels was calculated depending on the climatic data’s measurements. As the result of the study, th...
Targeted transfection increases siRNA uptake and gene silencing of primary endothelial cells in vitro - A quantitative study

NARCIS (Netherlands)

Asgeirsdottir, Sigridur A.; Talman, Eduard G.; de Graaf, Inge A.; Kamps, Jan A. A. M.; Satchell, Simon C.; Mathieson, Peter W.; Ruiters, Marcel H. J.; Molema, Grietje

2010-01-01

Applications of small-interfering RNA (siRNA) call for specific and efficient delivery of siRNA into particular cell types. We developed a novel, non-viral targeting system to deliver siRNA specifically into inflammation-activated endothelial cells. This was achieved by conjugating the cationic
Mechanically flexible optically transparent porous mono-crystalline silicon substrate

KAUST Repository

Rojas, Jhonathan Prieto; Syed, Ahad A.; Hussain, Muhammad Mustafa

2012-01-01

For the first time, we present a simple process to fabricate a thin (≥5μm), mechanically flexible, optically transparent, porous mono-crystalline silicon substrate. Relying only on reactive ion etching steps, we are able to controllably peel off a thin layer of the original substrate. This scheme is cost favorable as it uses a low-cost silicon <100> wafer and furthermore it has the potential for recycling the remaining part of the wafer that otherwise would be lost and wasted during conventional back-grinding process. Due to its porosity, it shows see-through transparency and potential for flexible membrane applications, neural probing and such. Our process can offer flexible, transparent silicon from post high-thermal budget processed device wafer to retain the high performance electronics on flexible substrates. © 2012 IEEE.
Folate conjugated Mn{sub 3}O{sub 4}@SiO{sub 2} nanoparticles for targeted magnetic resonance imaging in vivo

Energy Technology Data Exchange (ETDEWEB)

Yang, Xinyi [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Zhou, Zhiguo, E-mail: zgzhou@shnu.edu.cn [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Wang, Li; Tang, Caizhi; Yang, Hong [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Yang, Shiping, E-mail: shipingy@shnu.edu.cn [The Education Ministry Key Lab of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); The Education Ministry Key Lab of Pesticide and Chemical Biology, South China Agricultural University, Guangzhou 510641 (China)

2014-09-15

Graphical abstract: The Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA has been used as a T{sub 1}-MRI probe for in vivo. - Highlights: • The PEG and FA modified Mn{sub 3}O{sub 4}@SiO{sub 2} nanoparticles (Mn{sub 3}O{sub 4}@SiO{sub 2}–FA) were prepared. • Mn{sub 3}O{sub 4}@SiO{sub 2}–FA exhibited the good colloidal stability in the simulated biological medium. • Mn{sub 3}O{sub 4}@SiO{sub 2}–FA showed the targeting ability to HeLa cells overexpressed the FA receptor. • The T{sub 1}-weighted magnetic resonance (MR) imaging demonstrated the targeting ability of Mn{sub 3}O{sub 4}@SiO{sub 2}–FA in vivo tumor. - Abstract: The monodisperse silica-coated manganese oxide nanoparticles (Mn{sub 3}O{sub 4}@SiO{sub 2} NPs) were synthesized via the high temperature pyrolysis approach and were aminated through silanization. The amine-functionalized Mn{sub 3}O{sub 4} NPs enabled the covalent conjugation of hydrophilic methoxypoly(ethylene glycol) (PEG) and the targeting ligand of folate (FA) onto their surface. The formed PEG and FA modified Mn{sub 3}O{sub 4} NPs (Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA) exhibited the good colloidal stability in the simulated biological medium and the targeting ability to HeLa cells overexpressed the FA receptor. The T{sub 1}-weighted magnetic resonance (MR) imaging and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis of Mn{sub 3}O{sub 4}@SiO{sub 2}(PEG)–FA NPs further demonstrated their targeting ability in tumor.
Wide Band-Gap Semiconductors. 1991 Materials Research Society Symposium Proceedings

Science.gov (United States)

1992-09-01

ORIGIN OF POLYTYPES IN SiC AND ZnS 507 Volker Heine, C. Cheng, G.E. Engel, and R.I. Needs EPITAXIAL MONOCRYSTALLINE SiC FILMS GROWN ON Si BY LOW...carbon film component. INTRODUCTION One of the most challenging problems in diamond film research has been the growth of high quality, monocrystalline ...developing ZnS EL full color flat panel displays is that the insufficient intensity of blue light emission ( two orders of magnitude lower than that of red
Effects of nitrogen content in monocrystalline nano-CeO2 on the degradation of dye in indoor lighting

International Nuclear Information System (INIS)

Sun, Dongfeng; Gu, Mingjie; Li, Ruixing; Yin, Shu; Song, Xiaozhen; Zhao, Bin; Li, Chengqiang; Li, Junping; Feng, Zhihai; Sato, Tsugio

2013-01-01

Azo dyes are an abundant class of synthetic dyes, however their complex structure makes them difficult to biologically degrade. We sought to degrade acid orange 7 (AO7) using nitrogen-doped nano-CeO 2 , which is a promising alternative photocatalyst to nitrogen-doped TiO 2 . Nitrogen-doped monocrystalline CeO 2 nanoparticles with various nitrogen contents were synthesized solvothermally at 120 o C from Ce(NO 3 ) 3 ·6H 2 O, triethanolamine, and ethanol. The CeO 2 monocrystals were between 7 and 8 nm in diameter. Nitrogen was shown to be incorporated into CeO 2 lattice from the results of the lattice parameter calculations, X-ray photoelectron spectroscopy analysis and elemental analysis. The degradation of AO7 in water was investigated using a domestic 10 W compact fluorescent lamp. The degradation efficiency of AO7 by monocrystalline CeO 2 increased with increasing nitrogen content, reaching 97.6% for the sample with a N:Ce molar ratio of 0.3.
Electroluminescence of a-Si/c-Si heterojunction solar cells after high energy irradiation

Energy Technology Data Exchange (ETDEWEB)

Ferrara, Manuela

2009-11-24

The crystalline silicon as absorber material will certainly continue to dominate the market for space applications of solar cells. In the contribution under consideration the applicability of a-Si:H/c-Si heterojunction solar cells in space has been tested by the investigation of the cell modification by high energy protons and comparing the results to the degradation of homojunction crystalline silicon reference cells. The investigated solar cells have been irradiated with protons of different energies and doses. For all investigated solar cells the maximum damage happens for an energy of about 1.7 MeV and is mainly due to the decrease of the effective minority carrier diffusion length in the crystalline silicon absorber. Simulations carried out by AFORS-HET, a heterojunction simulation program, also confirmed this result. The main degradation mechanism for all types of devices is the monotonically decreasing charge carrier diffusion length in the p-type monocrystalline silicon absorber layer. For the heterojunction solar cell an enhancement of the photocurrent in the blue wavelength region has been observed but only in the case of heterojunction solar cell with intrinsic a-Si:H buffer layer. Additionally to the traditional characterization techniques the electroluminescence technique used for monitoring the modifications of the heteroluminescence technique used for monitoring the modifications of the heterointerface between amorphous silicon and crystalline silicon in solar cells after proton irradiation. A direct relation between minority carrier diffusion length and electroluminescence quantum efficiency has been observed but also details of the interface modification could be monitored by this technique.
Ultrasmooth, Highly Spherical Monocrystalline Gold Particles for Precision Plasmonics

KAUST Repository

Lee, You-Jin

2013-12-23

Ultrasmooth, highly spherical monocrystalline gold particles were prepared by a cyclic process of slow growth followed by slow chemical etching, which selectively removes edges and vertices. The etching process effectively makes the surface tension isotropic, so that spheres are favored under quasi-static conditions. It is scalable up to particle sizes of 200 nm or more. The resulting spherical crystals display uniform scattering spectra and consistent optical coupling at small separations, even showing Fano-like resonances in small clusters. The high monodispersity of the particles we demonstrate should facilitate the self-assembly of nanoparticle clusters with uniform optical resonances, which could in turn be used to fabricate optical metafluids. Narrow size distributions are required to control not only the spectral features but also the morphology and yield of clusters in certain assembly schemes. © 2013 American Chemical Society.

A remorin gene SiREM6, the target gene of SiARDP, from foxtail millet (Setaria italica) promotes high salt tolerance in transgenic Arabidopsis.

Science.gov (United States)

Yue, Jing; Li, Cong; Liu, Yuwei; Yu, Jingjuan

2014-01-01

Remorin proteins (REMs) form a plant-specific protein family, with some REMs being responsive to abiotic stress. However, the precise functions of REMs in abiotic stress tolerance are not clear. In this study, we identified 11 remorin genes from foxtail millet (Setaria italica) and cloned a remorin gene, SiREM6, for further investigation. The transcript level of SiREM6 was increased by high salt stress, low temperature stress and abscisic acid (ABA) treatment, but not by drought stress. The potential oligomerization of SiREM6 was examined by negative staining electron microscopy. The overexpression of SiREM6 improved high salt stress tolerance in transgenic Arabidopsis at the germination and seedling stages as revealed by germination rate, survival rate, relative electrolyte leakage and proline content. The SiREM6 promoter contains two dehydration responsive elements (DRE) and one ABA responsive element (ABRE). An ABA responsive DRE-binding transcription factor, SiARDP, and an ABRE-binding transcription factor, SiAREB1, were cloned from foxtail millet. SiARDP could physically bind to the DREs, but SiAREB1 could not. These results revealed that SiREM6 is a target gene of SiARDP and plays a critical role in high salt stress tolerance.
A remorin gene SiREM6, the target gene of SiARDP, from foxtail millet (Setaria italica promotes high salt tolerance in transgenic Arabidopsis.

Directory of Open Access Journals (Sweden)

Jing Yue

Full Text Available Remorin proteins (REMs form a plant-specific protein family, with some REMs being responsive to abiotic stress. However, the precise functions of REMs in abiotic stress tolerance are not clear. In this study, we identified 11 remorin genes from foxtail millet (Setaria italica and cloned a remorin gene, SiREM6, for further investigation. The transcript level of SiREM6 was increased by high salt stress, low temperature stress and abscisic acid (ABA treatment, but not by drought stress. The potential oligomerization of SiREM6 was examined by negative staining electron microscopy. The overexpression of SiREM6 improved high salt stress tolerance in transgenic Arabidopsis at the germination and seedling stages as revealed by germination rate, survival rate, relative electrolyte leakage and proline content. The SiREM6 promoter contains two dehydration responsive elements (DRE and one ABA responsive element (ABRE. An ABA responsive DRE-binding transcription factor, SiARDP, and an ABRE-binding transcription factor, SiAREB1, were cloned from foxtail millet. SiARDP could physically bind to the DREs, but SiAREB1 could not. These results revealed that SiREM6 is a target gene of SiARDP and plays a critical role in high salt stress tolerance.
Target swapping in PLD: An efficient approach for CdS/SiO{sub 2} and CdS:Ag(1%)/SiO{sub 2} nanocomposite thin films with enhanced luminescent properties

Energy Technology Data Exchange (ETDEWEB)

Saxena, Nupur, E-mail: n1saxena@gmail.com [Department of Physics & Astrophysics, University of Delhi, Delhi 110007 (India); Kumar, Pragati, E-mail: pkumar.phy@gmail.com [Department of Physics & Astrophysics, University of Delhi, Delhi 110007 (India); Department of Nano Sciences and Materials, Central University of Jammu, Rahya-Suchani (Bagla), Samba, 181143 Jammu, J& K (India); Gupta, Vinay [Department of Physics & Astrophysics, University of Delhi, Delhi 110007 (India)

2017-06-15

A novel synthesis method for luminescent and by-products (like CdO) free CdS/SiO{sub 2} and CdS:Ag(1%)/SiO{sub 2} (i.e. 1%Ag doped CdS/SiO{sub 2}) nanocomposite thin films at room temperature by pulsed laser deposition is reported. Targets of CdS, CdS:Ag(1%) and SiO{sub 2} are used to deposit CdS/SiO{sub 2} and CdS:Ag(1%)/SiO{sub 2} nanocomposite thin films by swapping them at a frequency ratio of 2:8 laser pulses/sec. X-ray photoelectron spectroscopy analysis ensures the ratio of CdS to SiO{sub 2} in nanocomposite as 21:79 which is nearly same as the ratio of incident pulses/sec (i.e. 2:8) on the two targets. Transmission electron micrographs visualize the formation of CdS/ CdS:Ag(1%) nanocrystals in nanocomposite systems after annealing at 500 °C. Highly intense and broad red emission is achieved from CdS/SiO{sub 2} and CdS:Ag(1%)/SiO{sub 2} nanocomposites. The efficiencies of emission from pristine CdS:SiO{sub 2} and CdS:Ag(1%)/SiO{sub 2} nanocomposites are found to be enhanced by approximately two times as compared to sole nanocrystalline CdS and CdS:Ag(1%) thin films respectively and further enhanced upto 7 times on annealing the nanocomposite systems at 500 °C. - Graphical abstract: A modified synthesis method for luminescent and by-products (like CdO) free undoped &1% Ag doped CdS/SiO{sub 2} (deposit CdS/SiO{sub 2} and CdS:Ag(1%)/SiO{sub 2}) nanocomposite thin films at room temperature by pulsed laser deposition is reported. Targets of CdS or CdS:Ag(1%) and SiO{sub 2} are used to deposit CdS/SiO{sub 2} and CdS:Ag(1%)/SiO{sub 2} nanocomposite thin films by swapping them at a frequency of 2:8 pulses/sec. X-ray photoelectron spectroscopy analysis ensures the ratio of CdS to SiO{sub 2} in nanocomposite as 21:79 which is nearly same as the ratio of incident pulses/sec (2:8) on the two targets. Transmission electron micrographs visualize the formation of CdS nanocrystals in nanocomposite systems after annealing at 500 °C. Intense and broad red emission is
Behavior of the potential-induced degradation of photovoltaic modules fabricated using flat mono-crystalline silicon cells with different surface orientations

Science.gov (United States)

Yamaguchi, Seira; Masuda, Atsushi; Ohdaira, Keisuke

2016-04-01

This paper deals with the dependence of the potential-induced degradation (PID) of flat, p-type mono-crystalline silicon solar cell modules on the surface orientation of solar cells. The investigated modules were fabricated from p-type mono-crystalline silicon cells with a (100) or (111) surface orientation using a module laminator. PID tests were performed by applying a voltage of -1000 V to shorted module interconnector ribbons with respect to an Al plate placed on the cover glass of the modules at 85 °C. A decrease in the parallel resistance of the (100)-oriented cell modules is more significant than that of the (111)-oriented cell modules. Hence, the performance of the (100)-oriented-cell modules drastically deteriorates, compared with that of the (111)-oriented-cell modules. This implies that (111)-oriented cells offer a higher PID resistance.
Enhancement of microelectronic device performances by photothermal annealing under SiCl4 ambient

International Nuclear Information System (INIS)

Hassen, M.; Ben Jaballah, A.; Hajji, M.; Ezzaouia, H.

2006-01-01

The use of low cost silicon wafers seems to be very attractive for photovoltaic and microelectronic devices. However, this material is widely contaminated by different impurities particularly transitions metals, which deteriorate the lifetimes and the bulk diffusion lengths of the minority charge carriers. One possible way to overcome this undesirable behavior is to include an efficient purification technique in the process of device fabrication. In this work, we present the effect of photothermal treatments of monocrystalline Czochralski silicon substrates under SiCl 4 /N 2 atmosphere using a thin sacrificial porous silicon layer. The main results show a decrease of the resistivity over 40 μm depth. The Hall mobility of the majority charge carriers is improved from 300 to 1417 cm 2 V -1 s -1 . The capacitance-voltage (C-V) characteristics of metal/SiO 2 /Si (MIS) structures indicate a decrease of carrier concentration which confirms the results obtained by Hall Effect and Van Der Pauw method. The reduction of boron concentration in Czochralski silicon may reduce boron- and oxygen related metastable defect centers
Towards flexible asymmetric MSM structures using Si microwires through contact printing

Science.gov (United States)

Khan, S.; Lorenzelli, L.; Dahiya, R.

2017-08-01

This paper presents development of flexible metal-semiconductor-metal devices using silicon (Si) microwires. Monocrystalline Si in the shape of microwires are used which are developed through standard photolithography and etching. These microwires are assembled on secondary flexible substrates through a dry transfer printing by using a polydimethylsiloxane stamp. The conductive patterns on Si microwires are printed using a colloidal silver nanoparticles based solution and an organic conductor i.e. poly (3,4-ethylene dioxthiophene) doped with poly (styrene sulfonate). A custom developed spray coating technique is used for conductive patterns on Si microwires. A comparative study of the current-voltage (I-V) responses is carried out in flat and bent orientations as well as the response to the light illumination of the wires is explored. Current variations as high as 17.1 μA are recorded going from flat to bend conditions, while the highest I on/I off ratio i.e. 43.8 is achieved with light illuminations. The abrupt changes in the current response due to light-on/off conditions validates these devices for fast flexible photodetector switches. These devices are also evaluated based on transfer procedure i.e. flip-over and stamp-assisted transfer printing for manipulating Si microwires and their subsequent post-processing. These new developments were made to study the most feasible approach for transfer printing of Si microwires and to harvest their capabilities such as photodetection and several other applications in the shape of metal-semiconductor-metal structures.
Investigation on powder metallurgy Cr-Si-Ta-Al alloy target for high-resistance thin film resistors with low temperature coefficient of resistance

International Nuclear Information System (INIS)

Wang, X.Y.; Zhang, Z.S.; Bai, T.

2010-01-01

The sputtering target for high-resistance thin film resistors plays a decisive role in temperature coefficient of resistance (TCR). Silicon-rich chromium (Cr)-silicon (Si) target was designed and smelted for high-resistance thin film resistors with low TCR. Valve metal tantalum (Ta) and aluminum (Al) were introduced to the Cr-Si target to improve the performance of the target prepared. The measures for grain refining in smelting Cr-Si-Ta-Al target were taken to improve the performance of the prepared target. The mechanism and role of grain refinement were discussed in the paper. The phase structure of the prepared target was detected by X-ray diffraction (XRD). Rate of temperature drop was studied to reduce the internal stress of alloy target and conquer the easy cracking disadvantage of silicon-rich target. The electrical properties of sputtered thin film resistors were tested to evaluate the performance of the prepared target indirectly.
Lamb wave propagation in monocrystalline silicon wafers.

Science.gov (United States)

Fromme, Paul; Pizzolato, Marco; Robyr, Jean-Luc; Masserey, Bernard

2018-01-01

Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. Guided ultrasonic waves offer the potential to efficiently detect micro-cracks in the thin wafers. Previous studies of ultrasonic wave propagation in silicon focused on effects of material anisotropy on bulk ultrasonic waves, but the dependence of the wave propagation characteristics on the material anisotropy is not well understood for Lamb waves. The phase slowness and beam skewing of the two fundamental Lamb wave modes A 0 and S 0 were investigated. Experimental measurements using contact wedge transducer excitation and laser measurement were conducted. Good agreement was found between the theoretically calculated angular dependency of the phase slowness and measurements for different propagation directions relative to the crystal orientation. Significant wave skew and beam widening was observed experimentally due to the anisotropy, especially for the S 0 mode. Explicit finite element simulations were conducted to visualize and quantify the guided wave beam skew. Good agreement was found for the A 0 mode, but a systematic discrepancy was observed for the S 0 mode. These effects need to be considered for the non-destructive testing of wafers using guided waves.
MDR1 siRNA loaded hyaluronic acid-based CD44 targeted nanoparticle systems circumvent paclitaxel resistance in ovarian cancer

Science.gov (United States)

Yang, Xiaoqian; Lyer, Arun K.; Singh, Amit; Choy, Edwin; Hornicek, Francis J.; Amiji, Mansoor M.; Duan, Zhenfeng

2015-02-01

Development of multidrug resistance (MDR) is an almost universal phenomenon in patients with ovarian cancer, and this severely limits the ultimate success of chemotherapy in the clinic. Overexpression of the MDR1 gene and corresponding P-glycoprotein (Pgp) is one of the best known MDR mechanisms. MDR1 siRNA based strategies were proposed to circumvent MDR, however, systemic, safe, and effective targeted delivery is still a major challenge. Cluster of differentiation 44 (CD44) targeted hyaluronic acid (HA) based nanoparticle has been shown to successfully deliver chemotherapy agents or siRNAs into tumor cells. The goal of this study is to evaluate the ability of HA-PEI/HA-PEG to deliver MDR1 siRNA and the efficacy of the combination of HA-PEI/HA-PEG/MDR1 siRNA with paclitaxel to suppress growth of ovarian cancer. We observed that HA-PEI/HA-PEG nanoparticles can efficiently deliver MDR1 siRNA into MDR ovarian cancer cells, resulting in down-regulation of MDR1 and Pgp expression. Administration of HA-PEI/HA-PEG/MDR1 siRNA nanoparticles followed by paclitaxel treatment induced a significant inhibitory effect on the tumor growth, decreased Pgp expression and increased apoptosis in MDR ovarian cancer mice model. Our findings suggest that CD44 targeted HA-PEI/HA-PEG/MDR1 siRNA nanoparticles can serve as a therapeutic tool with great potentials to circumvent MDR in ovarian cancer.
Radiation effects of energetic thorium ions in monocrystalline Mg O and Si O2

International Nuclear Information System (INIS)

Abuassy, M.K.

1995-01-01

Radiation effects of energetic thorium ions in the energy range ∼ (100-1200) eV in both Mg O and Si O 2 single crystal have been investigated with program MARLOWE which simulate the collision cascades using the binary collision approximation. The effect of binding parameters on the radiation effects have been studied. The calculations covered the range, energy loss and Frenkel pair production. The results of MARLOWE have been compared with results of program TRIM and with the energy-partition theory of lindhard
Simulation study on discrete charge effects of SiNW biosensors according to bound target position using a 3D TCAD simulator.

Science.gov (United States)

Chung, In-Young; Jang, Hyeri; Lee, Jieun; Moon, Hyunggeun; Seo, Sung Min; Kim, Dae Hwan

2012-02-17

We introduce a simulation method for the biosensor environment which treats the semiconductor and the electrolyte region together, using the well-established semiconductor 3D TCAD simulator tool. Using this simulation method, we conduct electrostatic simulations of SiNW biosensors with a more realistic target charge model where the target is described as a charged cube, randomly located across the nanowire surface, and analyze the Coulomb effect on the SiNW FET according to the position and distribution of the target charges. The simulation results show the considerable variation in the SiNW current according to the bound target positions, and also the dependence of conductance modulation on the polarity of target charges. This simulation method and the results can be utilized for analysis of the properties and behavior of the biosensor device, such as the sensing limit or the sensing resolution.
Simulation study on discrete charge effects of SiNW biosensors according to bound target position using a 3D TCAD simulator

International Nuclear Information System (INIS)

Chung, In-Young; Moon, Hyunggeun; Jang, Hyeri; Lee, Jieun; Kim, Dae Hwan; Seo, Sung Min

2012-01-01

We introduce a simulation method for the biosensor environment which treats the semiconductor and the electrolyte region together, using the well-established semiconductor 3D TCAD simulator tool. Using this simulation method, we conduct electrostatic simulations of SiNW biosensors with a more realistic target charge model where the target is described as a charged cube, randomly located across the nanowire surface, and analyze the Coulomb effect on the SiNW FET according to the position and distribution of the target charges. The simulation results show the considerable variation in the SiNW current according to the bound target positions, and also the dependence of conductance modulation on the polarity of target charges. This simulation method and the results can be utilized for analysis of the properties and behavior of the biosensor device, such as the sensing limit or the sensing resolution. (paper)
Targeted transfection increases siRNA uptake and gene silencing of primary endothelial cells in vitro--a quantitative study.

Science.gov (United States)

Asgeirsdóttir, Sigridur A; Talman, Eduard G; de Graaf, Inge A; Kamps, Jan A A M; Satchell, Simon C; Mathieson, Peter W; Ruiters, Marcel H J; Molema, Grietje

2010-01-25

Applications of small-interfering RNA (siRNA) call for specific and efficient delivery of siRNA into particular cell types. We developed a novel, non-viral targeting system to deliver siRNA specifically into inflammation-activated endothelial cells. This was achieved by conjugating the cationic amphiphilic lipid SAINT to antibodies recognizing the inflammatory cell adhesion molecule E-selectin. These anti-E-selectin-SAINT lipoplexes (SAINTarg) maintained antigen recognition capacity of the parental antibody in vitro, and ex vivo in human kidney tissue slices subjected to inflammatory conditions. Regular SAINT mediated transfection resulted in efficient gene silencing in human microvascular endothelial cells (HMEC-1) and conditionally immortalized glomerular endothelial cells (ciGEnC). However, primary human umbilical vein endothelial cells (HUVEC) transfected poorly, a phenomenon that we could quantitatively correlate with a cell-type specific capacity to facilitate siRNA uptake. Importantly, SAINTarg increased siRNA uptake and transfection specificity for activated endothelial cells. Transfection with SAINTarg delivered significantly more siRNA into activated HUVEC, compared to transfection with non-targeted SAINT. The enhanced uptake of siRNA was corroborated by improved silencing of both gene- and protein expression of VE-cadherin in activated HUVEC, indicating that SAINTarg delivered functionally active siRNA into endothelial cells. The obtained results demonstrate a successful design of a small nucleotide carrier system with improved and specific siRNA delivery into otherwise difficult-to-transfect primary endothelial cells, which in addition reduced considerably the amount of siRNA needed for gene silencing. Copyright 2009 Elsevier B.V. All rights reserved.
Solar Photovoltaic and Liquid Natural Gas Opportunities for Command Naval Region Hawaii

Science.gov (United States)

2014-12-01

panels made of monocrystalline (c-Si) panels (EPRI, 2010). The price breakdown is as follows: Table 8. Utility-Scale Solar PV Power Plant O&M Costs...Battery Energy Storage System CBA Cost Benefit Analysis CNG Containerized Natural Gas CNRH Command Naval Region Hawaii c-Si Monocrystalline ...of ground-mounted solar-PV panels on the West Loch Peninsula, on Pearl Harbor Naval Base. The second proposed project is a land lease to an
Fab’-bearing siRNA TNFα-loaded nanoparticles targeted to colonic macrophages offer an effective therapy for experimental colitis

Science.gov (United States)

Hamed, Laroui; Emilie, Viennois; Xiao, Bo; Canup, Brandon S.; Duke, Geem; Denning, Timothy L.; Didier, Merlin

2014-01-01

Patients suffering from Inflammatory Bowel Disease (IBD) are currently treated by systemic drugs that can have significant side effects. Thus, it would be highly desirable to target TNFα siRNA (a therapeutic molecule) to the inflamed tissue. Here, we demonstrate that TNFα siRNA can be efficiently loaded into nanoparticles (NPs) made of poly (lactic acid) poly (ethylene glycol) block copolymer (PLA-PEG), and that grafting of the Fab’ portion of the F4/80 Ab (Fab’-bearing) onto the NP surface via maleimide/thiol group-mediated covalent bonding improves the macrophage (MP)-targeting kinetics of the NPs to RAW264.7 cells in vitro. Direct binding was shown between MPs and the Fab’-bearing NPs. Next, we orally administered hydrogel (chitosan/alginate)-encapsulated Fab’-bearing TNFα-siRNA-loaded NPs to 3% dextran sodium sulfate (DSS)-treated mice and investigated the therapeutic effect on colitis. In vivo, the release of TNFα-siRNA-loaded NPs into the mouse colon attenuated colitis more efficiently when the NPs were covered with Fab’-bearing, compared to uncovered NPs. All DSS-induced parameters of colonic inflammation (e.g., weight loss, myeloperoxidase activity, and Iκbα accumulation) were more attenuated Fab’-bearing NPs loaded with TNFα siRNA than without the Fab’-bearing. Grafting the Fab’-bearing onto the NPs improved the kinetics of endocytosis as well as the MP-targeting ability, as indicated by flow cytometry. Collectively, our results show that Fab’-bearing PLA-PEG NPs are powerful and efficient nanosized tools for delivering siRNAs into colonic macrophages. PMID:24810114
Analysis of the siRNA-Mediated Gene Silencing Process Targeting Three Homologous Genes Controlling Soybean Seed Oil Quality.

Science.gov (United States)

Lu, Sha; Yin, Xiaoyan; Spollen, William; Zhang, Ning; Xu, Dong; Schoelz, James; Bilyeu, Kristin; Zhang, Zhanyuan J

2015-01-01

In the past decade, RNA silencing has gained significant attention because of its success in genomic scale research and also in the genetic improvement of crop plants. However, little is known about the molecular basis of siRNA processing in association with its target transcript. To reveal this process for improving hpRNA-mediated gene silencing in crop plants, the soybean GmFAD3 gene family was chosen as a test model. We analyzed RNAi mutant soybean lines in which three members of the GmFAD3 gene family were silenced. The silencing levels of FAD3A, FAD3B and FAD3C were correlated with the degrees of sequence homology between the inverted repeat of hpRNA and the GmFAD3 transcripts in the RNAi lines. Strikingly, transgenes in two of the three RNAi lines were heavily methylated, leading to a dramatic reduction of hpRNA-derived siRNAs. Small RNAs corresponding to the loop portion of the hairpin transcript were detected while much lower levels of siRNAs were found outside of the target region. siRNAs generated from the 318-bp inverted repeat were found to be diced much more frequently at stem sequences close to the loop and associated with the inferred cleavage sites on the target transcripts, manifesting "hot spots". The top candidate hpRNA-derived siRNA share certain sequence features with mature miRNA. This is the first comprehensive and detailed study revealing the siRNA-mediated gene silencing mechanism in crop plants using gene family GmFAD3 as a test model.
Targeted Delivery of siRNA to Macrophages for Anti-inflammatory Treatment

OpenAIRE

Kim, Sang-Soo; Ye, Chunting; Kumar, Priti; Chiu, Isaac; Subramanya, Sandesh; Wu, Haoquan; Shankar, Premlata; Manjunath, N

2010-01-01

Inflammation mediated by tumor necrosis factor-α (TNF-α) and the associated neuronal apoptosis characterizes a number of neurologic disorders. Macrophages and microglial cells are believed to be the major source of TNF-α in the central nervous system (CNS). Here, we show that suppression of TNF-α by targeted delivery of small interfering RNA (siRNA) to macrophage/microglial cells dramatically reduces lipopolysaccharide (LPS)-induced neuroinflammation and neuronal apoptosis in vivo. Because ma...
Influence of irradiation on mechanical properties of Si-Ge alloys

Energy Technology Data Exchange (ETDEWEB)

Sichinava, Avtandil; Bokuchava, Guram; Chubinidze, Giorgi; Archuadze, Giorgi [Ilia Vekua Sukhumi Institute of Physics and Technology, Tbilisi (Georgia); Gapishvili, Nodar [Ilia Vekua Sukhumi Institute of Physics and Technology, Tbilisi (Georgia); Georgian Technical University, Tbilisi (Georgia)

2017-07-15

Impact of various irradiation (Ar and He ions, high energy electrons) on microhardness and indentation of monocrystalline Si{sub 0,98}Ge{sub 0,02} alloy is studied. Samples of Si and SiGe alloy are obtained by Czochralski (CZ) method in the [111] direction in the atmosphere of high purity Ar. High energy electron irradiation with fluence of ∝10{sup 12} cm{sup -2} is conducted at the Clinac 2100iX. Ar and He ion implantation is performed on modernized ''VEZUVI-3M'' plant. It is shown that for all types of irradiation the microhardness and indentation modulus versus load are characterized by reverse indentation size effect (ISE). With the increase of fluences of Ar and He ions, the maximum value of the effect increases. At high values of loading force impact on the indenter the mechanical characteristics slowly decrease. Impact of isochronous thermal annealing on mechanical properties of high energy electron irradiated samples is studied. Non-monotonic changes of microhardness and indentation modulus are revealed in the temperature range of 200-260 C. It is proposed that such changes are caused by radiation defects transformation. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Participation of oxygen and carbon in formation of oxidation-induced stacking faults in monocrystalline silicon

Directory of Open Access Journals (Sweden)

Иван Федорович Червоный

2015-11-01

Full Text Available It is experimentally established, that density of oxidation-induced stacking faults (OISF in the boron doped monocrystalline silicon plates, that above, than it is more relation of oxygen atoms concentration to carbon atoms concentration in them.On research results of geometry of OISF rings in the different sections of single-crystal geometry of areas is reconstructed with their different closeness. At adjustment of the growing modes of single-crystals of silicon the increase of output of suitable product is observed
Effect of defects on electrical properties of 4H-SiC Schottky diodes

International Nuclear Information System (INIS)

Ben Karoui, M.; Gharbi, R.; Alzaied, N.; Fathallah, M.; Tresso, E.; Scaltrito, L.; Ferrero, S.

2008-01-01

Most of power electronic circuits use power semiconductor switching devices which ideally present infinite resistance when off, zero resistance when on, and switch instantaneously between those two states. Switches and rectifiers are key components in power electronic systems, which cover a wide range of applications, from power transmission to control electronics and power supplies. Typical power switching devices such as diodes, thyristors, and transistors are based on a monocrystalline silicon semiconductor or silicon carbide. Silicon is less expensive, more widely used, and a more versatile processing material than silicon carbide. The silicon carbide (SiC) has properties that allow devices with high power voltage rating and high operating temperatures. The technology overcomes some crystal growth obstacles, by using the hydrogen in the fabrication of 4H-SiC wafers. The presence of structural defects on 4H-SiC wafers was shown by different techniques such as optical microscopy and scanning electron microscopy. The presence of different SiC polytypes inclusions was found by Raman spectroscopy. Schottky diodes were realized on investigated wafers in order to obtain information about the correlation between those defects and electrical properties of the devices. The diodes with voltage breakdown as 600 V and ideality factor as 1.05 were obtained and characterized after packaging

Construction and Biological Evaluation of a Novel Integrin ανβ3-Specific Carrier for Targeted siRNA Delivery In Vitro

Directory of Open Access Journals (Sweden)

Xueqi Chen

2017-02-01

Full Text Available (1 Background: The great potential of RNA interference (RNAi-based gene therapy is premised on the effective delivery of small interfering RNAs (siRNAs to target tissues and cells. Hence, we aimed at developing and examining a novel integrin αvβ3-specific delivery carrier for targeted transfection of siRNA to malignant tumor cells; (2 Methods: Arginine-glycine-aspartate motif (RGD was adopted as a tissue target for specific recognition of integrin αvβ3. To enable siRNA binding, a chimeric peptide was synthesized by adding nonamer arginine residues (9R at the carboxy terminus of cyclic-RGD dimer, designated as c(RGD2-9R. The efficiency of 9R peptide transferring siRNA was biologically evaluated in vitro by flow cytometry, confocal microscopy, and Western blot; (3 Results: An optimal 10:1 molar ratio of c(RGD2-9R to siRNA was confirmed by the electrophoresis on agarose gels. Both the flow cytometry and confocal microscopy results testified that transfection of c(RGD2-9R as an siRNA delivery carrier was obviously higher than the naked-siRNA group. The results of Western blot demonstrated that these 9R peptides were able to transduce siRNA to HepG2 cells in vitro, resulting in efficient gene silencing; and (4 Conclusion: The chimeric peptide of c(RGD2-9R can be developed as an effective siRNA delivery carrier and shows potential as a new strategy for RNAi-based gene therapy.
Analysis of the siRNA-Mediated Gene Silencing Process Targeting Three Homologous Genes Controlling Soybean Seed Oil Quality.

Directory of Open Access Journals (Sweden)

Sha Lu

Full Text Available In the past decade, RNA silencing has gained significant attention because of its success in genomic scale research and also in the genetic improvement of crop plants. However, little is known about the molecular basis of siRNA processing in association with its target transcript. To reveal this process for improving hpRNA-mediated gene silencing in crop plants, the soybean GmFAD3 gene family was chosen as a test model. We analyzed RNAi mutant soybean lines in which three members of the GmFAD3 gene family were silenced. The silencing levels of FAD3A, FAD3B and FAD3C were correlated with the degrees of sequence homology between the inverted repeat of hpRNA and the GmFAD3 transcripts in the RNAi lines. Strikingly, transgenes in two of the three RNAi lines were heavily methylated, leading to a dramatic reduction of hpRNA-derived siRNAs. Small RNAs corresponding to the loop portion of the hairpin transcript were detected while much lower levels of siRNAs were found outside of the target region. siRNAs generated from the 318-bp inverted repeat were found to be diced much more frequently at stem sequences close to the loop and associated with the inferred cleavage sites on the target transcripts, manifesting "hot spots". The top candidate hpRNA-derived siRNA share certain sequence features with mature miRNA. This is the first comprehensive and detailed study revealing the siRNA-mediated gene silencing mechanism in crop plants using gene family GmFAD3 as a test model.
Lipoprotein-biomimetic nanostructure enables efficient targeting delivery of siRNA to Ras-activated glioblastoma cells via macropinocytosis

Science.gov (United States)

Huang, Jia-Lin; Jiang, Gan; Song, Qing-Xiang; Gu, Xiao; Hu, Meng; Wang, Xiao-Lin; Song, Hua-Hua; Chen, Le-Pei; Lin, Ying-Ying; Jiang, Di; Chen, Jun; Feng, Jun-Feng; Qiu, Yong-Ming; Jiang, Ji-Yao; Jiang, Xin-Guo; Chen, Hong-Zhuan; Gao, Xiao-Ling

2017-05-01

Hyperactivated Ras regulates many oncogenic pathways in several malignant human cancers including glioblastoma and it is an attractive target for cancer therapies. Ras activation in cancer cells drives protein internalization via macropinocytosis as a key nutrient-gaining process. By utilizing this unique endocytosis pathway, here we create a biologically inspired nanostructure that can induce cancer cells to `drink drugs' for targeting activating transcription factor-5 (ATF5), an overexpressed anti-apoptotic transcription factor in glioblastoma. Apolipoprotein E3-reconstituted high-density lipoprotein is used to encapsulate the siRNA-loaded calcium phosphate core and facilitate it to penetrate the blood-brain barrier, thus targeting the glioblastoma cells in a macropinocytosis-dependent manner. The nanostructure carrying ATF5 siRNA exerts remarkable RNA-interfering efficiency, increases glioblastoma cell apoptosis and inhibits tumour cell growth both in vitro and in xenograft tumour models. This strategy of targeting the macropinocytosis caused by Ras activation provides a nanoparticle-based approach for precision therapy in glioblastoma and other Ras-activated cancers.
Optical performance of thin films produced by the pulsed laser deposition of SiAlON and Er targets

Energy Technology Data Exchange (ETDEWEB)

Camps, I., E-mail: camps@io.cfmac.csic.es [Laser Processing Group, Instituto de Óptica, CSIC, C/Serrano 121, 28006 Madrid (Spain); Ramírez, J.M. [MIND-IN2UB, Departament d’Electrònica, Universitat de Barcelona, c/Martí i Franqués 1, 08028 Barcelona (Spain); Mariscal, A.; Serna, R. [Laser Processing Group, Instituto de Óptica, CSIC, C/Serrano 121, 28006 Madrid (Spain); Garrido, B. [MIND-IN2UB, Departament d’Electrònica, Universitat de Barcelona, c/Martí i Franqués 1, 08028 Barcelona (Spain); Perálvarez, M.; Carreras, J. [IREC, Fundació Privada Institut de Recerca en Energia de Catalunya (Spain); Barradas, N.P.; Alves, L.C. [C" 2TN, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela (Portugal); Alves, E. [IPFN, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela (Portugal)

2015-05-01

Highlights: • PLD production of Er-doped thin films from a low cost commercial SiAlON target. • The role of the ablation fluence on the composition, optical properties as well as on the light emission performance at 1.5 μm. • The optimized performance is obtained for the samples deposited at the higher used ablation energy density. Further improvement was achieved through annealing. - Abstract: We report the preparation and optical performance of thin films produced by pulsed laser deposition in vacuum at room temperature, by focusing an ArF excimer laser onto two separate targets: a commercial ceramic SiAlON and a metallic Er target. As a result of the alternate deposition Er:SiAlON films were formed. The as grown films exhibited an Er-related emission peaking at 1532 nm. The role of the PLD energy density during deposition on the final matrix film was investigated, in order to achieve an optimized matrix composition with enhanced optical properties, and its effect on the light emission performance.
CMOS compatible generic batch process towards flexible memory on bulk monocrystalline silicon (100)

KAUST Repository

Ghoneim, Mohamed T.

2014-12-01

Today\\'s mainstream flexible electronics research is geared towards replacing silicon either totally, by having organic devices on organic substrates, or partially, by transferring inorganic devices onto organic substrates. In this work, we present a pragmatic approach combining the desired flexibility of organic substrates and the ultra-high integration density, inherent in silicon semiconductor industry, to transform bulk/inflexible silicon into an ultra-thin mono-crystalline fabric. We also show the effectiveness of this approach in achieving fully flexible electronic systems. Furthermore, we provide a progress report on fabricating various memory devices on flexible silicon fabric and insights for completely flexible memory modules on silicon fabric.
CMOS compatible generic batch process towards flexible memory on bulk monocrystalline silicon (100)

KAUST Repository

Ghoneim, Mohamed T.; Rojas, Jhonathan Prieto; Kutbee, Arwa T.; Hanna, Amir; Hussain, Muhammad Mustafa

2014-01-01

Today's mainstream flexible electronics research is geared towards replacing silicon either totally, by having organic devices on organic substrates, or partially, by transferring inorganic devices onto organic substrates. In this work, we present a pragmatic approach combining the desired flexibility of organic substrates and the ultra-high integration density, inherent in silicon semiconductor industry, to transform bulk/inflexible silicon into an ultra-thin mono-crystalline fabric. We also show the effectiveness of this approach in achieving fully flexible electronic systems. Furthermore, we provide a progress report on fabricating various memory devices on flexible silicon fabric and insights for completely flexible memory modules on silicon fabric.
Machinability of Al-SiC metal matrix composites using WC, PCD and MCD inserts

Energy Technology Data Exchange (ETDEWEB)

Beristain, J.; Gonzalo, O.; Sanda, A.

2014-04-01

The aim of this work is the study of the machinability of aluminium-silicon carbide Metal Matrix Composites (MMC) in turning operations. The cutting tools used were hard metal (WC) with and without coating, different grades and geometries of Poly-Crystalline Diamond (PCD) and Mono-Crystalline Diamond (MCD). The work piece material was AMC225xe, composed of aluminium-copper alloy AA 2124 and 25% wt of SiC, being the size of the SiC particles around 3 {mu}m. Experiments were conducted at various cutting speeds and cutting parameters in facing finishing operations, measuring the surface roughness, cutting forces and tool wear. The worn surface of the cutting tool was examined by Scanning Electron Microscope (SEM). It was observed that the Built Up Edge (BUE) and stuck material is higher in the MCD tools than in the PCD tools. The BUE acts as a protective layer against abrasive wear of the tool. (Author)
Connexin43 Mediated Delivery of ADAMTS5 Targeting siRNAs from Mesenchymal Stem Cells to Synovial Fibroblasts.

Directory of Open Access Journals (Sweden)

Shuo Liu

Full Text Available Osteoarthritis is a joint-destructive disease that has no effective cure. Human mesenchymal stem cells (hMSCs could offer therapeutic benefit in the treatment of arthritic diseases by suppressing inflammation and permitting tissue regeneration, but first these cells must overcome the catabolic environment of the diseased joint. Likewise, gene therapy also offers therapeutic promise given its ability to directly modulate key catabolic factors that mediate joint deterioration, although it too has limitations. In the current study, we explore an approach that combines hMSCs and gene therapy. Specifically, we test the use of hMSC as a vehicle to deliver ADAMTS5 (an aggrecanase with a key role in osteoarthritis-targeting siRNAs to SW982 synovial fibroblast-like cells via connexin43 containing gap junctions. Accordingly, we transduced hMSCs with ADAMTS5-targeting shRNA or non-targeted shRNA, and co-cultured them with synovial fibroblasts to allow delivery of siRNAs from hMSC to synovial fibroblasts. We found that co-culture of hMSCs-shRNA-ADAMTS5 and synovial fibroblasts reduced ADAMTS5 expression relative to co-culture of hMSCs-shRNA-control and synovial fibroblasts. Furthermore, ADAMTS5 was specifically reduced in the synovial fibroblasts populations as determined by fluorescence-activated cell sorting, suggesting transfer of the siRNA between cells. To test if Cx43-containing gap junctions are involved in the transfer of siRNA, we co-cultured hMSCs-shRNA-ADAMTS5 cells with synovial fibroblasts in which connexin43 was knocked down. Under these conditions, ADAMTS5 levels were not inhibited by co-culture, indicating that connexin43 mediates the delivery of siRNA from hMSCs to synovial fibroblasts. In total, our findings demonstrate that hMSCs can function as donor cells to host and deliver siRNAs to synovial fibroblasts via connexin43 gap junction in vitro. These data may have implications in the combination of hMSCs and gene therapy to treat diseases
Connexin43 Mediated Delivery of ADAMTS5 Targeting siRNAs from Mesenchymal Stem Cells to Synovial Fibroblasts.

Science.gov (United States)

Liu, Shuo; Niger, Corinne; Koh, Eugene Y; Stains, Joseph P

2015-01-01

Osteoarthritis is a joint-destructive disease that has no effective cure. Human mesenchymal stem cells (hMSCs) could offer therapeutic benefit in the treatment of arthritic diseases by suppressing inflammation and permitting tissue regeneration, but first these cells must overcome the catabolic environment of the diseased joint. Likewise, gene therapy also offers therapeutic promise given its ability to directly modulate key catabolic factors that mediate joint deterioration, although it too has limitations. In the current study, we explore an approach that combines hMSCs and gene therapy. Specifically, we test the use of hMSC as a vehicle to deliver ADAMTS5 (an aggrecanase with a key role in osteoarthritis)-targeting siRNAs to SW982 synovial fibroblast-like cells via connexin43 containing gap junctions. Accordingly, we transduced hMSCs with ADAMTS5-targeting shRNA or non-targeted shRNA, and co-cultured them with synovial fibroblasts to allow delivery of siRNAs from hMSC to synovial fibroblasts. We found that co-culture of hMSCs-shRNA-ADAMTS5 and synovial fibroblasts reduced ADAMTS5 expression relative to co-culture of hMSCs-shRNA-control and synovial fibroblasts. Furthermore, ADAMTS5 was specifically reduced in the synovial fibroblasts populations as determined by fluorescence-activated cell sorting, suggesting transfer of the siRNA between cells. To test if Cx43-containing gap junctions are involved in the transfer of siRNA, we co-cultured hMSCs-shRNA-ADAMTS5 cells with synovial fibroblasts in which connexin43 was knocked down. Under these conditions, ADAMTS5 levels were not inhibited by co-culture, indicating that connexin43 mediates the delivery of siRNA from hMSCs to synovial fibroblasts. In total, our findings demonstrate that hMSCs can function as donor cells to host and deliver siRNAs to synovial fibroblasts via connexin43 gap junction in vitro. These data may have implications in the combination of hMSCs and gene therapy to treat diseases like
Structural defects in monocrystalline silicon: from radiation ones to growing and technological

International Nuclear Information System (INIS)

Gerasimenko, N.N.; Pavlyuchenko, M.N.; Dzhamanbalin, K.K.

2001-01-01

The systematical review of properties and conditions of radiation structures in monocrystalline silicon including own defects (elementary and complex, disordered fields) as well as defect-impurity formations is presented. The most typical examples of principle effects influence of known defects on radiation-induced processes (phase transformations, diffusion and heteration and others are considered. Experimental facts and models of silicon radiation amorphization have been analyzed in comparison of state of the radiation amorphization radiation problem of metals and alloys. The up-to-date status of the problem of the radiation defects physics are discussed, including end-of-range -, n+-, rod-like- defects. The phenomenon self-organization in crystals with defects has been considered. The examples of directed using radiation defects merged in independent trend - defects engineering - are given
Amelioration of cirrhotic portal hypertension by targeted cyclooxygenase-1 siRNA delivery to liver sinusoidal endothelium with polyethylenimine grafted hyaluronic acid.

Science.gov (United States)

Lin, Liteng; Cai, Mingyue; Deng, Shaohui; Huang, Wensou; Huang, Jingjun; Huang, Xinghua; Huang, Mingsheng; Wang, Yong; Shuai, Xintao; Zhu, Kangshun

2017-10-01

Portal hypertension (PH), a leading cause of mortality in cirrhosis, lacks effective clinical therapeutic strategies. The increased thromboxane A 2 (TXA 2 ), derived primarily from the upregulation of cyclooxygenase-1 (COX-1) in cirrhotic liver sinusoidal endothelial cells (LSECs), is responsible for hepatic endothelial dysfunction and PH. Thus, blocking the COX-1 pathway in cirrhotic LSECs may benefit the treatment of PH. In this study, hyaluronate-graft-polyethylenimine (HA-PEI) was synthesized for the targeted delivery of COX-1 siRNA to LSECs. Compared to non-targeted PEI, HA-PEI mediated much more efficient siRNA delivery, which resulted in potent targeted gene silencing in LSECs. In vivo, HA-PEI notably increased the accumulation of siRNA along the sinusoidal lining of the liver, inhibited over-activation of the COX-1/TXA 2 pathway in LSECs, and successfully reduced portal pressure in cirrhotic mice. These results highlight the potential of HA-PEI complexed siRNA to serve as a LSECs-specific nanomedical system for effective gene therapy in PH. Copyright © 2017 Elsevier Inc. All rights reserved.
Folate-targeted amphiphilic cyclodextrin nanoparticles incorporating a fusogenic peptide deliver therapeutic siRNA and inhibit the invasive capacity of 3D prostate cancer tumours.

Science.gov (United States)

Evans, James C; Malhotra, Meenakshi; Sweeney, Katrina; Darcy, Raphael; Nelson, Colleen C; Hollier, Brett G; O'Driscoll, Caitriona M

2017-10-30

The main barrier to the development of an effective RNA interference (RNAi) therapy is the lack of a suitable delivery vector. Modified cyclodextrins have emerged in recent years for the delivery of siRNA. In the present study, a folate-targeted amphiphilic cyclodextrin was formulated using DSPE-PEG 5000 -folate to target prostate cancer cells. The fusogenic peptide GALA was included in the formulation to aid in the endosomal release of siRNA. Targeted nanoparticles were less than 200nm in size with a neutral surface charge. The complexes were able to bind siRNA and protect it from serum nucleases. Incubation with excess free folate resulted in a significant decrease in the uptake of targeted nanoparticles in LNCaP and PC3 cells, both of which have been reported to have differing pathways of folate uptake. There was a significant reduction in the therapeutic targets, ZEB1 and NRP1 at mRNA and protein level following treatment with targeted complexes. In preliminary functional assays using 3D spheroids, treatment of PC3 tumours with targeted complexes with ZEB1 and NRP1 siRNA resulted in more compact colonies relative to the untargeted controls and inhibited infiltration into the Matrigel™ layer. Copyright © 2017 Elsevier B.V. All rights reserved.
Formation, structure, and phonon confinement effect of nanocrystalline Si1-xGex in SiO2-Si-Ge cosputtered films

International Nuclear Information System (INIS)

Yang, Y.M.; Wu, X.L.; Siu, G.G.; Huang, G.S.; Shen, J.C.; Hu, D.S.

2004-01-01

Using magnetron cosputtering of SiO 2 , Ge, and Si targets, Si-based SiO 2 :Ge:Si films were fabricated for exploring the influence of Si target proportion (P Si ) and annealing temperature (Ta) on formation, local structure, and phonon properties of nanocrystalline Si 1-x Ge x (nc-Si 1-x Ge x ). At low P Si and Ta higher than 800 deg. C, no nc-Si 1-x Ge x but a kind of composite nanocrystal consisting of a Ge core, GeSi shell, and amorphous Si outer shell is formed in the SiO 2 matrix. At moderate P Si , nc-Si 1-x Ge x begins to be formed at Ta=800 deg. C and coexists with nc-Ge at Ta=1100 deg. C. At high P Si , it was disclosed that both optical phonon frequency and lattice spacing of nc-Si 1-x Ge x increase with raising Ta. The possible origin of this phenomenon is discussed by considering three factors, the phonon confinement, strain effect, and composition variation of nc-Si 1-x Ge x . This work will be helpful in understanding the growth process of ternary GeSiO films and beneficial to further investigations on optical properties of nc-Ge 1-x Si x in the ternary matrix
NIR-to-visible upconversion nanoparticles for fluorescent labeling and targeted delivery of siRNA

International Nuclear Information System (INIS)

Jiang Shan; Zhang Yong; Lim, Kian Meng; Sim, Eugene K W; Ye Lei

2009-01-01

Near-infrared (NIR)-to-visible upconversion fluorescent nanoparticles were synthesized and used for imaging and targeted delivery of small interfering RNA (siRNA) to cancer cells. Silica-coated NaYF 4 upconversion nanoparticles (UCNs) co-doped with lanthanide ions (Yb/Er) were synthesized. Folic acid and anti-Her2 antibody conjugated UCNs were used to fluorescently label the folate receptors of HT-29 cells and Her2 receptors of SK-BR-3 cells, respectively. The intracellular uptake of the folic acid and antibody conjugated UCNs was visualized using a confocal fluorescence microscope equipped with an NIR laser. siRNA was attached to anti-Her2 antibody conjugated UCNs and the delivery of these nanoparticles to SK-BR-3 cells was studied. Meanwhile, a luciferase assay was established to confirm the gene silencing effect of siRNA. Upconversion nanoparticles can serve as a fluorescent probe and delivery system for simultaneous imaging and delivery of biological molecules.
NIR-to-visible upconversion nanoparticles for fluorescent labeling and targeted delivery of siRNA

Science.gov (United States)

Jiang, Shan; Zhang, Yong; Lim, Kian Meng; Sim, Eugene K. W.; Ye, Lei

2009-04-01

Near-infrared (NIR)-to-visible upconversion fluorescent nanoparticles were synthesized and used for imaging and targeted delivery of small interfering RNA (siRNA) to cancer cells. Silica-coated NaYF4 upconversion nanoparticles (UCNs) co-doped with lanthanide ions (Yb/Er) were synthesized. Folic acid and anti-Her2 antibody conjugated UCNs were used to fluorescently label the folate receptors of HT-29 cells and Her2 receptors of SK-BR-3 cells, respectively. The intracellular uptake of the folic acid and antibody conjugated UCNs was visualized using a confocal fluorescence microscope equipped with an NIR laser. siRNA was attached to anti-Her2 antibody conjugated UCNs and the delivery of these nanoparticles to SK-BR-3 cells was studied. Meanwhile, a luciferase assay was established to confirm the gene silencing effect of siRNA. Upconversion nanoparticles can serve as a fluorescent probe and delivery system for simultaneous imaging and delivery of biological molecules.
Receptor-targeted aptamer-siRNA conjugate-directed transcriptional regulation of HIV-1

Science.gov (United States)

Zhou, Jiehua; Lazar, Daniel; Li, Haitang; Xia, Xin; Satheesan, Sangeetha; Charlins, Paige; O'Mealy, Denis; Akkina, Ramesh; Saayman, Sheena; Weinberg, Marc S.; Rossi, John J.; Morris, Kevin V.

2018-01-01

Gene-based therapies represent a promising therapeutic paradigm for the treatment of HIV-1, as they have the potential to maintain sustained viral inhibition with reduced treatment interventions. Such an option may represent a long-term treatment alternative to highly active antiretroviral therapy. Methods: We previously described a therapeutic approach, referred to as transcriptional gene silencing (TGS), whereby small noncoding RNAs directly inhibit the transcriptional activity of HIV-1 by targeting sites within the viral promoter, specifically the 5' long terminal repeat (LTR). TGS differs from traditional RNA interference (RNAi) in that it is characterized by concomitant silent-state epigenetic marks on histones and DNA. To deliver TGS-inducing RNAs, we developed functional RNA conjugates based on the previously reported dual function of the gp120 (A-1) aptamer conjugated to 27-mer Dicer-substrate anti-HIV-1 siRNA (dsiRNA), LTR-362. Results: We demonstrate here that high levels of processed guide RNAs localize to the nucleus in infected T lymphoblastoid CEM cell line and primary human CD4+ T-cells. Treatment of the aptamer-siRNA conjugates induced TGS with an ~10-fold suppression of viral p24 levels as measured at day 12 post infection. To explore the silencing efficacy of aptamer-siRNA conjugates in vivo, HIV-1-infected humanized NOD/SCID/IL2 rγnull mice (hu-NSG) were treated with the aptamer-siRNA conjugates. Systemic delivery of the A-1-stick-LTR-362 27-mer siRNA conjugates suppressed HIV-1 infection and protected CD4+ T cell levels in viremia hu-NSG mice. Principle conclusions: Collectively these data suggest that the gp120 aptamer-dsiRNA conjugate design is suitable for systemic delivery of small RNAs that can be used to suppress HIV-1. PMID:29556342
EGF receptor targeted lipo-oligocation polyplexes for antitumoral siRNA and miRNA delivery

Science.gov (United States)

Müller, Katharina; Klein, Philipp M.; Heissig, Philipp; Roidl, Andreas; Wagner, Ernst

2016-11-01

Antitumoral siRNA and miRNA delivery was demonstrated by epidermal growth factor receptor (EGFR) targeted oligoaminoamide polyplexes. For this purpose, the T-shaped lipo-oligomer 454 was used to complex RNA into a core polyplex, which was subsequently functionalized with the targeting peptide ligand GE11 via a polyethylene glycol (PEG) linker. To this end, free cysteines on the surface of 454 polyplex were coupled with a maleimide-PEG-GE11 reagent (Mal-GE11). Resulting particles with sizes of 120-150 nm showed receptor-mediated uptake into EGFR-positive T24 bladder cancer cells, MDA-MB 231 breast cancer cells and Huh7 liver cancer cells. Furthermore, these formulations led to ligand-dependent gene silencing. RNA interference (RNAi) triggered antitumoral effects were observed for two different therapeutic RNAs, a miRNA-200c mimic or EG5 siRNA. Using polyplexes modified with a ratio of 0.8 molar equivalents of Mal-GE11, treatment of T24 or MDA-MB 231 cancer cells with miR-200c led to the expected decreased proliferation and migration, changes in cell cycle and enhanced sensitivity towards doxorubicin. Delivery of EG5 siRNA into Huh7 cells resulted in antitumoral activity with G2/M arrest, triggered by loss of mitotic spindle separation and formation of mono-astral spindles. These findings demonstrate the potential of GE11 ligand-containing RNAi polyplexes for cancer treatment.
β-FeSi2 films prepared on 6H-SiC substrates by magnetron sputtering

Science.gov (United States)

Hong, Li; Hongbin, Pu; Chunlei, Zheng; Zhiming, Chen

2015-06-01

β-FeSi2 thin films have been successfully prepared by magnetron sputtering and post rapid thermal annealing method on 6H-SiC (0001) substrates using a FeSi2 target and a Si target. X-ray diffraction (XRD) and Raman spectroscopy are applied to analyze the formation of β-FeSi2 films. XRD spectra reveal that the amorphous FeSi2 films are transformed to β-FeSi2 phase as the annealing temperature is increased from 500 to 900 °C for 5 min and the optimal annealing temperature is 900 °C. The formation of β-FeSi2 is also confirmed by Raman spectroscopy. Scanning electron microscope (SEM) observations indicate that the film is flat, relatively compact and the interface between β-FeSi2 and 6H-SiC is clear. Atomic force microscope (AFM) measurements demonstrate that the surface roughness confirmed by the root mean square (RMS) of the β-FeSi2 film is 0.87 nm. Near-infrared spectrophotometer observation shows that the absorption coefficient is of the order of 105 cm-1 and the optical band-gap of the β-FeSi2 film is 0.88 eV. The β-FeSi2 film with high crystal quality is fabricated by co-sputtering a FeSi2 target and a Si target for 60 min and annealing at 900 °C for 5 min. Project supported by the National Natural Science Foundation of China (No. 51177134) and the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2015JM6286).
The chemical composition and band gap of amorphous Si:C:N:H layers

Energy Technology Data Exchange (ETDEWEB)

Swatowska, Barbara, E-mail: swatow@agh.edu.pl [AGH University of Science and Technology, Department of Electronics, Mickiewicza Av. 30, 30-059 Krakow (Poland); Kluska, Stanislawa; Jurzecka-Szymacha, Maria [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza Av. 30, 30-059 Krakow (Poland); Stapinski, Tomasz [AGH University of Science and Technology, Department of Electronics, Mickiewicza Av. 30, 30-059 Krakow (Poland); Tkacz-Smiech, Katarzyna [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza Av. 30, 30-059 Krakow (Poland)

2016-05-15

Highlights: • Six type of amorphous hydrogenated films were obtained and analysed. • Investigated chemical bondings strongly influenced energy gap values. • Analysed layers could be applied as semiconductors and also as dielectrics. - Abstract: In this work we presented the correlation between the chemical composition of amorphous Si:C:N:H layers of various content of silicon, carbon and nitrogen, and their band gap. The series of amorphous Si:C:N:H layers were obtained by plasma assisted chemical vapour deposition method in which plasma was generated by RF (13.56 MHz, 300 W) and MW (2.45 GHz, 2 kW) onto monocrystalline silicon Si(001) and borosilicate glass. Structural studies were based on FTIR transmission spectrum registered within wavenumbers 400–4000 cm{sup −1}. The presence of Si−C, Si−N, C−N, C=N, C=C, C≡N, Si−H and C−H bonds was shown. The values band gap of the layers have been determined from spectrophotometric and ellipsometric measurements. The respective values are contained in the range between 1.64 eV – characteristic for typical semiconductor and 4.21 eV – for good dielectric, depending on the chemical composition and atomic structure of the layers.
siRNA targeting PLK-1 induces apoptosis of synoviocytes in rheumatoid arthritis

International Nuclear Information System (INIS)

Wada, Makoto; Kawahito, Yutaka; Kimura, Shinya; Kohno, Masataka; Ishino, Hidetaka; Kimura, Mizuho; Omoto, Atsushi; Yamamoto, Aihiro; Hamaguchi, Masahide; Tsubouchi, Yasunori; Tokunaga, Daisaku; Hojo, Tatsuya; Ashihara, Eishi; Maekawa, Taira; Yoshikawa, Toshikazu

2007-01-01

Polo-like kinase-1 (PLK-1) is a member of the PLK family and participates in the control of cell mitosis. Here, we show that immunoreactive PLK-1 is strongly expressed in synoviocytes and some infiltrative mononuclear cells in synovial tissues from patients with rheumatoid arthritis (RA), while patients with osteoarthritis and injury show little or no expression of PLK-1 in synovial tissues. Western blot analysis shows that PLK is expressed and its expression is enhanced by IL-1β in RA synoviocytes. IL-1β also enhanced the cell growth of RA synoviocytes. Moreover, siRNA targeted against PLK-1 significantly decreases the expression of PLK-1 of RA synoviocytes stimulated by IL-1β and suppresses the proliferation of these synoviocytes through apoptosis. These findings suggest that PLK-1 plays a critical role in the proliferation of RA synoviocytes leading to bone destruction, and siRNA against PLK-1 is potentially useful for the treatment of RA

Photoluminescence of Mg_2Si films fabricated by magnetron sputtering

International Nuclear Information System (INIS)

Liao, Yang-Fang; Xie, Quan; Xiao, Qing-Quan; Chen, Qian; Fan, Meng-Hui; Xie, Jing; Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di

2017-01-01

Highlights: • High quality Mg_2Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg_2Si films was reported. • The Mg_2Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg_2Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg_2Si-based light-emitting devices, Mg_2Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg_2Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg_2Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg_2Si film on Si (111) displays polycrystalline structure, whereas Mg_2Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg_2Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg_2Si films was observed for the first time. The PL emission wavelengths of Mg_2Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg_2Si films on glass substrate is much larger than that of Mg_2Si film on Si (111) substrate. The activation energy of 18 meV is
The structure of Cu-Cd alloys obtained by electrolysis on monocrystalline silver substrates

International Nuclear Information System (INIS)

Lagiewka, E.

1981-01-01

The structure of Cu-Cd alloys obtained by electrolysis on monocrystalline silver cathodes with a surface parallel to the (111), (110) and (100) planes has been investigated. It has been found that depending on the range of the cathode potentials, one-phase (phase α) or two-phase (phase α + cadmium) alloy are obtained. In the alloys the occurrence of twins has been observed, the orientation of which is the result of twinning along the [111] planes of crystallites with epitaxial orientation with respect to the cathode surface and of a random orientation of crystallites. The volume of the layer containing crystallites with a random arrangement increases with the obtaining potential of the alloy and with the decrease in the surface density of the cathode atoms. (author)
The Effects of Cells Temperature Increment and Variations of Irradiation for Monocrystalline Photovoltaic

Science.gov (United States)

Fuad Rahman Soeharto, Faishal; Hermawan

2017-04-01

Photovoltaic cell technology has been developed to meet the target of 17% Renewable Energy in 2025 accordance with Indonesia Government Regulation No. 5 2006. Photovoltaic cells are made of semiconductor materials, namely silicon or germanium (p-n junction). These cells need the light that comes from solar irradiation which brings energy photons to convert light energy into electrical energy. It is different from the solar heater that requires heat energy or thermal of sunlight that is normally used for drying or heating water. Photovoltaic cells requires energy photons to perform the energy conversion process, the photon energy can be derived from sunlight. Energy photon is taken from the sun light along with the advent of heat due to black-body radiation, which can lead to temperature increments of photovoltaic cells. Increment of 1°C can decreased photovoltaic cell voltage of up to 2.3 mV per cell. In this research, it will be discuss the analysis of the effect of rising temperatures and variations of irradiation on the type monocrystalline photovoltaic. Those variation are analyzed, simulated and experiment by using a module of experiment. The test results show that increment temperature from 25° C to 80° C at cell of photovoltaic decrease the output voltage of the photovoltaic cell at 4.21 V, and it also affect the power output of the cell which decreases up to 0.7523 Watt. In addition, the bigger the value of irradiation received by cell at amount of 1000 W / m2, produce more output power cells at the same temperature.
Shock compression of monocrystalline copper: Experiments, characterization, and analysis

International Nuclear Information System (INIS)

Cao Buyang; Lassila, David H.; Huang Chongxiang; Xu Yongbo; Meyers, Marc Andre

2010-01-01

Monocrystalline copper samples with [0 0 1] and [2 2 1] orientations were subjected to shock/recovery experiments at 30 and 57 GPa and 90 K. The slip system activity and the microstructural evolution were investigated. Different defect structures, including dislocations, stacking faults, twins, microbands, and recrystallized grains were observed in the specimens. The residual microstructures were dependent on crystalline orientation and pressure. The differences with crystalline orientations are most likely due to different resolved shear stresses on specific crystalline planes. The geometric relationships between the shock propagation direction and crystalline orientation are presented under uniaxial strain. It is shown that the [2 2 1] orientation, by virtue of having fewer highly activated slip systems, exhibits greater concentration of deformation with more intense shear on the primary system. This, in turn leads to greater local temperature rise and full recrystallization, in spite of the thermodynamic residual temperature of ∼500 K and rapid cooling (within 20 s) to ambient temperature. The profuse observation of microbands is interpreted in terms of the mechanism proposed by Huang and Gray [J.C. Huang, G.T. Gray III, Acta Metallurgica 37 (1989) 3335-3347].
Thermal Stability of siRNA Modulates Aptamer- conjugated siRNA Inhibition

Directory of Open Access Journals (Sweden)

Alexey Berezhnoy

2012-01-01

Full Text Available Oligonucleotide aptamer-mediated in vivo cell targeting of small interfering RNAs (siRNAs is emerging as a useful approach to enhance the efficacy and reduce the adverse effects resulting from siRNA-mediated genetic interference. A current main impediment in aptamer-mediated siRNA targeting is that the activity of the siRNA is often compromised when conjugated to an aptamer, often requiring labor intensive and time consuming design and testing of multiple configurations to identify a conjugate in which the siRNA activity has not been significantly reduced. Here, we show that the thermal stability of the siRNA is an important parameter of siRNA activity in its conjugated form, and that siRNAs with lower melting temperature (Tm are not or are minimally affected when conjugated to the 3′ end of 2′F-pyrimidine-modified aptamers. In addition, the configuration of the aptamer-siRNA conjugate retains activity comparable with the free siRNA duplex when the passenger strand is co-transcribed with the aptamer and 3′ overhangs on the passenger strand are removed. The approach described in this paper significantly reduces the time and effort necessary to screening siRNA sequences that retain biological activity upon aptamer conjugation, facilitating the process of identifying candidate aptamer-siRNA conjugates suitable for in vivo testing.
Effects of thermomechanical processing on the recrystallization texture and grain size of Al-1%Si sputtering target material

DEFF Research Database (Denmark)

Li, X.R.; Xu, C.L.; Huang, T.L.

2015-01-01

An Al-1%Si alloy was solution treated and deformed by conventional cold rolling to different strains, followed by annealing at various temperatures until complete recrystallization. The microstructures of annealed samples were characterized by electron backscatter diffraction. It is found that un...... that under optimal conditions of cold rolling and annealing, the microstructure desired for sputtering target materials with fine, uniformly sized and randomly textured grains can be obtained for the Al-1%Si alloy....
Low cost monocrystalline silicon sheet fabrication for solar cells by advanced ingot technology

Science.gov (United States)

Fiegl, G. F.; Bonora, A. C.

1980-01-01

The continuous liquid feed (CLF) Czochralski furnace and the enhanced I.D. slicing technology for the low-cost production of monocrystalline silicon sheets for solar cells are discussed. The incorporation of the CLF system is shown to improve ingot production rate significantly. As demonstrated in actual runs, higher than average solidification rates (75 to 100 mm/hr for 150 mm 1-0-0 crystals) can be achieved, when the system approaches steady-state conditions. The design characteristics of the CLF furnace are detailed, noting that it is capable of precise control of dopant impurity incorporation in the axial direction of the crystal. The crystal add-on cost is computed to be $11.88/sq m, considering a projected 1986 25-slice per cm conversion factor with an 86% crystal growth yield.
Disruption of Aedes aegypti olfactory system development through chitosan/siRNA nanoparticle targeting of semaphorin-1a.

Directory of Open Access Journals (Sweden)

Keshava Mysore

Full Text Available Despite the devastating impact of mosquito-borne illnesses on human health, surprisingly little is known about mosquito developmental biology, including development of the olfactory system, a tissue of vector importance. Analysis of mosquito olfactory developmental genetics has been hindered by a lack of means to target specific genes during the development of this sensory system. In this investigation, chitosan/siRNA nanoparticles were used to target semaphorin-1a (sema1a during olfactory system development in the dengue and yellow fever vector mosquito Aedes aegypti. Immunohistochemical analyses and anterograde tracing of antennal sensory neurons, which were used to track the progression of olfactory development in this species, revealed antennal lobe defects in sema1a knockdown fourth instar larvae. These findings, which correlated with a larval odorant tracking behavioral phenotype, identified previously unreported roles for Sema1a in the developing insect larval olfactory system. Analysis of sema1a knockdown pupae also revealed a number of olfactory phenotypes, including olfactory receptor neuron targeting and projection neuron defects coincident with a collapse in the structure and shape of the antennal lobe and individual glomeruli. This study, which is to our knowledge the first functional genetic analysis of insect olfactory development outside of D. melanogaster, identified critical roles for Sema1a during Ae. aegypti larval and pupal olfactory development and advocates the use of chitosan/siRNA nanoparticles as an effective means of targeting genes during post-embryonic Ae. aegypti development. Use of siRNA nanoparticle methodology to understand sensory developmental genetics in mosquitoes will provide insight into the evolutionary conservation and divergence of key developmental genes which could be exploited in the development of both common and species-specific means for intervention.
SKI2 mediates degradation of RISC 5'-cleavage fragments and prevents secondary siRNA production from miRNA targets in Arabidopsis.

Science.gov (United States)

Branscheid, Anja; Marchais, Antonin; Schott, Gregory; Lange, Heike; Gagliardi, Dominique; Andersen, Stig Uggerhøj; Voinnet, Olivier; Brodersen, Peter

2015-12-15

Small regulatory RNAs are fundamental in eukaryotic and prokaryotic gene regulation. In plants, an important element of post-transcriptional control is effected by 20-24 nt microRNAs (miRNAs) and short interfering RNAs (siRNAs) bound to the ARGONAUTE1 (AGO1) protein in an RNA induced silencing complex (RISC). AGO1 may cleave target mRNAs with small RNA complementarity, but the fate of the resulting cleavage fragments remains incompletely understood. Here, we show that SKI2, SKI3 and SKI8, subunits of a cytoplasmic cofactor of the RNA exosome, are required for degradation of RISC 5', but not 3'-cleavage fragments in Arabidopsis. In the absence of SKI2 activity, many miRNA targets produce siRNAs via the RNA-dependent RNA polymerase 6 (RDR6) pathway. These siRNAs are low-abundant, and map close to the cleavage site. In most cases, siRNAs were produced 5' to the cleavage site, but several examples of 3'-spreading were also identified. These observations suggest that siRNAs do not simply derive from RDR6 action on stable 5'-cleavage fragments and hence that SKI2 has a direct role in limiting secondary siRNA production in addition to its function in mediating degradation of 5'-cleavage fragments. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.
Intracellular siRNA delivery dynamics of integrin-targeted, PEGylated chitosan-poly(ethylene imine) hybrid nanoparticles

DEFF Research Database (Denmark)

Ragelle, Héloïse; Colombo, Stefano; Pourcelle, Vincent

2015-01-01

chitosan-poly(ethylene imine) hybrid nanoparticles. The amount of intracellular siRNA delivered by αvβ3-targeted versus non-targeted nanoparticles was quantified in the human non-small cell lung carcinoma cell line H1299 expressing enhanced green fluorescent protein (EGFP) using a stem-loop reverse...... that these nanoparticles might end up in late endosomes or lysosomes without releasing their cargo to the cell cytoplasm. Thus, the silencing efficiency of the chitosan-based nanoparticles is strongly dependent on the uptake and the intracellular trafficking in H1299 EGFP cells, which is critical information towards...
Copper, Aluminum and Nickel: A New Monocrystalline Orthodontic Alloy

Science.gov (United States)

Wierenga, Mark

Introduction: This study was designed to evaluate, via tensile and bend testing, the mechanical properties of a newly-developed monocrystalline orthodontic archwire comprised of a blend of copper, aluminum, and nickel (CuAlNi). Methods: The sample was comprised of three shape memory alloys; CuAlNi, copper nickel titanium (CuNiTi), and nickel titanium (NiTi); from various orthodontic manufacturers in both 0.018" round and 0.019" x 0.025" rectangular dimensions. Additional data was gathered for similarly sized stainless steel and beta-titanium archwires as a point of reference for drawing conclusions about the relative properties of the archwires. Measurements of loading and unloading forces were recorded in both tension and deflection testing. Repeated-measure ANOVA (alpha= 0.05) was used to compare loading and unloading forces across wires and one-way ANOVA (alpha= 0.05) was used to compare elastic moduli and hysteresis. To identify significant differences, Tukey post-hoc comparisons were performed. Results: The modulus of elasticity, deflection forces, and hysteresis profiles of CuAlNi were significantly different than the other superelastic wires tested. In all tests, CuAlNi had a statistically significant lower modulus of elasticity compared to the CuNiTi and NiTi wires (P orthodontic metallurgy.
Endothermic decompositions of inorganic monocrystalline thin plates. II. Displacement rate modulation of the reaction front

Science.gov (United States)

Bertrand, G.; Comperat, M.; Lallemant, M.

1980-09-01

Copper sulfate pentahydrate dehydration into trihydrate was investigated using monocrystalline platelets with (110) crystallographic orientation. Temperature and pressure conditions were selected so as to obtain elliptical trihydrate domains. The study deals with the evolution, vs time, of elliptical domain dimensions and the evolution, vs water vapor pressure, of the {D}/{d} ratio of ellipse axes and on the other hand of the interface displacement rate along a given direction. The phenomena observed are not basically different from those yielded by the overall kinetic study of the solid sample. Their magnitude, however, is modulated depending on displacement direction. The results are analyzed within the scope of our study of endothermic decomposition of solids.
SiASR4, the Target Gene of SiARDP from Setaria italica, Improves Abiotic Stress Adaption in Plants.

Science.gov (United States)

Li, Jianrui; Dong, Yang; Li, Cong; Pan, Yanlin; Yu, Jingjuan

2016-01-01

Drought and other types of abiotic stresses negatively affect plant growth and crop yields. The abscisic acid-, stress-, and ripening-induced (ASR) proteins play important roles in the protection of plants against abiotic stress. However, the regulatory pathway of the gene encoding this protein remains to be elucidated. In this study, the foxtail millet ( Setaria italica ) ASR gene, SiASR4 , was cloned and characterized. SiASR4 localized to the cell nucleus, cytoplasm and cytomembrane, and the protein contained 102 amino acids, including an ABA/WDS (abscisic acid/water-deficit stress) domain, with a molecular mass of 11.5 kDa. The abundance of SiASR4 transcripts increased after treatment with ABA, NaCl, and PEG in foxtail millet seedlings. It has been reported that the S. italica ABA-responsive DRE-binding protein (SiARDP) binds to a DNA sequence with a CCGAC core and that there are five dehydration-responsive element (DRE) motifs within the SiASR4 promoter. Our analyses demonstrated that the SiARDP protein could bind to the SiASR4 promoter in vitro and in vivo . The expression of SiASR4 increased in SiARDP -overexpressing plants. SiASR4 -transgenic Arabidopsis and SiASR4 -overexpressing foxtail millet exhibited enhanced tolerance to drought and salt stress. Furthermore, the transcription of stress-responsive and reactive oxygen species (ROS) scavenger-associated genes was activated in SiASR4 transgenic plants. Together, these findings show that SiASR4 functions in the adaption to drought and salt stress and is regulated by SiARDP via an ABA-dependent pathway.
siRNA as an alternative therapy against viral infections

Directory of Open Access Journals (Sweden)

Hana A. Pawestri

2012-07-01

Full Text Available siRNA (small interfering ribonucleic acid adalah sebuah metode yang dapat digunakan untuk mengatasi infeksi virus yang prinsip kerjanya berdasarkan metode komplementer dsRNA (double stranded RNA pada RNA virus sehingga menyebabkan kegagalan proses transkripsi (silencing. Untuk lebih memahami bagaimana proses kerja dan ulasan penelitian siRNA yang terkini, di dalam tulisan ini ditinjau siRNA sebagai metoda yang dikembangkan untuk mengatasi infeksi dan meneliti efeknya pada replikasi beberapa virus seperti Hepatitis C, Influenza, Polio, dan HIV. Kami menemukan bahwa urutan basa nukleotida dari target siRNA sangat penting. Hal tersebut harus homolog dengan target RNA virus dan tidak menganggu RNA sel inang. Untuk mengurangi kegagalan terapi siRNA oleh adanya mutasi, digunakan beberapa siRNA yang sekaligus menjadi target RNA virus yang berbeda. Namun demikian, terapi siRNA masih menghadapi beberapa kesulitan seperti pengiriman (transfer khusus ke jaringan yang terinfeksi dan perlindungan siRNA dari perusakan oleh nuklease. Berdasarkan beberapa penelitian yang telah dilakukan, siRNA dapat digunakan sebagai alternatif untuk mengobati infeksi yang disebabkan oleh virus. Terapi tersebut direkomendasikan untuk dilakukan uji klinis dengan memperhatikan beberapa aspek seperti desain siRNA dan mekanisme transfer. (Health Science Indones 2010; 1: 58 - 65 Kata kunci: siRNA, infeksi virus, target virus, alternatif terapi Abstract SiRNA is a promising method to deal with viral infections. The principle of siRNA is based on the complementarily of (synthetic dsRNA to an RNA virus which, in consequence, will be silenced. Many studies are currently examining the effects of siRNA on replication of diverse virus types like Hepatitis C, polio and HIV. The choice of the siRNA target sequence is crucial. It has to be very homologous to the target RNA, but it cannot target RNA of the host cell. To reduce the possibility for the virus to escape from the siRNA therapy by
SKI2 mediates degradation of RISC 5′-cleavage fragments and prevents secondary siRNA production from miRNA targets in Arabidopsis

Science.gov (United States)

Branscheid, Anja; Marchais, Antonin; Schott, Gregory; Lange, Heike; Gagliardi, Dominique; Andersen, Stig Uggerhøj; Voinnet, Olivier; Brodersen, Peter

2015-01-01

Small regulatory RNAs are fundamental in eukaryotic and prokaryotic gene regulation. In plants, an important element of post-transcriptional control is effected by 20–24 nt microRNAs (miRNAs) and short interfering RNAs (siRNAs) bound to the ARGONAUTE1 (AGO1) protein in an RNA induced silencing complex (RISC). AGO1 may cleave target mRNAs with small RNA complementarity, but the fate of the resulting cleavage fragments remains incompletely understood. Here, we show that SKI2, SKI3 and SKI8, subunits of a cytoplasmic cofactor of the RNA exosome, are required for degradation of RISC 5′, but not 3′-cleavage fragments in Arabidopsis. In the absence of SKI2 activity, many miRNA targets produce siRNAs via the RNA-dependent RNA polymerase 6 (RDR6) pathway. These siRNAs are low-abundant, and map close to the cleavage site. In most cases, siRNAs were produced 5′ to the cleavage site, but several examples of 3′-spreading were also identified. These observations suggest that siRNAs do not simply derive from RDR6 action on stable 5′-cleavage fragments and hence that SKI2 has a direct role in limiting secondary siRNA production in addition to its function in mediating degradation of 5′-cleavage fragments. PMID:26464441
Photoluminescence of Mg{sub 2}Si films fabricated by magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Liao, Yang-Fang [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Xie, Quan, E-mail: qxie@gzu.edu.cn [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xiao, Qing-Quan [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Engineering Center for Avionics Electrical and Information Network of Guizhou Provincial Colleges and Universities, Anshun 561000 (China); Chen, Qian; Fan, Meng-Hui [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); Xie, Jing [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China); School of Physics and Electronic Science of Guizhou Normal University, Guiyang 550001 (China); Huang, Jin; Zhang, Jin-Min; Ma, Rui; Wang, Shan-Lan; Wu, Hong-Xian; Fang, Di [Institute of Advanced Optoelectronic Materials and Technology of College of BigData and Information Engineering of Guizhou University, Guiyang 550025 (China)

2017-05-01

Highlights: • High quality Mg{sub 2}Si films were grown on Si (111) and glass substrates with magnetron sputtering, respectively. • The first observation of Photoluminescence (PL) of Mg{sub 2}Si films was reported. • The Mg{sub 2}Si PL emission wavelengths are almost independence on temperature in the range of 77–300 K. • The strongest PL emissions may be attributed to interstitial Mg donor level to valence band transitions. • The activation energy of Mg{sub 2}Si is determined from the quenching of major luminescence peaks. - Abstract: To understand the photoluminescence mechanisms and optimize the design of Mg{sub 2}Si-based light-emitting devices, Mg{sub 2}Si films were fabricated on silicon (111) and glass substrates by magnetron sputtering technique, and the influences of different substrates on the photoelectric properties of Mg{sub 2}Si films were investigated systematically. The crystal structure, cross-sectional morphology, composition ratios and temperature-dependent photoluminescence (PL) of the Mg{sub 2}Si films were examined using X-ray diffraction (XRD), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and PL measurement system, respectively. XRD results indicate that the Mg{sub 2}Si film on Si (111) displays polycrystalline structure, whereas Mg{sub 2}Si film on glass substrate is of like-monocrystalline structure.SEM results show that Mg{sub 2}Si film on glass substrate is very compact with a typical dense columnar structure, and the film on Si substrate represents slight delamination phenomenon. EDS results suggest that the stoichiometry of Mg and Si is approximately 2:1. Photoluminescence (PL) of Mg{sub 2}Si films was observed for the first time. The PL emission wavelengths of Mg{sub 2}Si are almost independence on temperature in the range of 77–300 K. The PL intensity decreases gradually with increasing temperature. The PL intensity of Mg{sub 2}Si films on glass substrate is much larger than that of Mg
Targeted delivery of CD44s-siRNA by ScFv overcomes de novo resistance to cetuximab in triple negative breast cancer.

Science.gov (United States)

Fu, Wenyan; Sun, Hefen; Zhao, Yang; Chen, Mengting; Yang, Lipeng; Yang, Xueli; Jin, Wei

2018-05-16

The overexpression of EGFR often occurs in TNBC, and the anti-EGFR receptor antibody cetuximab is used widely to treat metastatic cancer in the clinic. However, EGFR-targeted therapies have been developed for TNBC without clinical success. In this study, we show that impaired EGFR degradation is crucial for resistance to cetuximab, which depends on the cell surface molecule CD44. To further investigate the role of CD44 in EGFR signaling and its treatment potential, we developed a targeting fusion protein composed of an anti-EGFR scFv generated from cetuximab and truncated protamine, called Ce-tP. CD44 siRNA can be specifically delivered into EGFR-positive TNBC cells by Ce-tP. Efficient knockdown of CD44 and suppression of both EGFR and downstream signaling by the Ce-tP/siRNA complex were observed in EGFR-positive TNBC cells. More importantly, our results also showed that targeted delivery of siRNA specific for CD44 can efficiently overcome resistance to EGFR targeting in TNBC cells both in vitro and in vivo. Overall, our results establish a new principle to achieve EGFR inhibition in TNBC and limit drug resistance. Copyright © 2018 Elsevier Ltd. All rights reserved.
The highly conserved 5' untranslated region as an effective target towards the inhibition of Enterovirus 71 replication by unmodified and appropriate 2'-modified siRNAs

Directory of Open Access Journals (Sweden)

Deng Jun-Xia

2012-08-01

Full Text Available Abstract Background Enterovirus 71 (EV71 is a highly infectious agent that plays an etiological role in hand, foot, and mouth disease. It is associated with severe neurological complications and has caused significant mortalities in recent large-scale outbreaks. Currently, no effective vaccine or specific clinical therapy is available against EV71. Methods Unmodified 21 nucleotide small interfering RNAs (siRNAs and classic 2′-modified (2′-O-methylation or 2′-fluoro modification siRNAs were designed to target highly conserved 5′ untranslated region (UTR of the EV71 genome and employed as anti-EV71 agents. Real-time TaqMan RT-PCR, western blot analysis and plaque assays were carried out to evaluate specific viral inhibition by the siRNAs. Results Transfection of rhabdomyosarcoma (RD cells with siRNAs targeting the EV71 genomic 5′ UTR significantly delayed and alleviated the cytopathic effects of EV71 infection, increased cell viability in EV71-infected RD cells. The inhibitory effect on EV71 replication was sequence-specific and dosage-dependent, with significant corresponding decreases in viral RNA, VP1 protein and viral titer. Appropriate 2′-modified siRNAs exhibited similar RNA interference (RNAi activity with dramatically increased serum stability in comparison with unmodified counterparts. Conclusion Sequences were identified within the highly conserved 5′ UTR that can be targeted to effectively inhibit EV71 replication through RNAi strategies. Appropriate 2′-modified siRNAs provide a promising approach to optimizing siRNAs to overcome barriers on RNAi-based antiviral therapies for broader administration.
Targeted delivery of siRNA to activated T cells via transferrin-polyethylenimine (Tf-PEI) as a potential therapy of asthma.

Science.gov (United States)

Xie, Yuran; Kim, Na Hyung; Nadithe, Venkatareddy; Schalk, Dana; Thakur, Archana; Kılıç, Ayşe; Lum, Lawrence G; Bassett, David J P; Merkel, Olivia M

2016-05-10

Asthma is a worldwide health problem. Activated T cells (ATCs) in the lung, particularly T helper 2 cells (Th2), are strongly associated with inducing airway inflammatory responses and chemoattraction of inflammatory cells in asthma. Small interfering RNA (siRNA) as a promising anti-sense molecule can specifically silence inflammation related genes in ATCs, however, lack of safe and efficient siRNA delivery systems limits the application of siRNA as a therapeutic molecule in asthma. Here, we designed a novel pulmonary delivery system of siRNA, transferrin-polyethylenimine (Tf-PEI), to selectively deliver siRNA to ATCs in the lung. Tf-PEI polyplexes demonstrated optimal physicochemical properties such as size, distribution, zeta-potential, and siRNA condensation efficiency. Moreover, in vitro studies showed significantly enhanced cellular uptake and gene knockdown mediated by Tf-PEI polyplexes in human primary ATCs. Biodistribution of polyplexes in a murine asthmatic model confirmed that Tf-PEI polyplexes can efficiently and selectively deliver siRNA to ATCs. In conclusion, the present work proves the feasibility to target ATCs in asthma via Tf receptor. This strategy could potentially be used to design an efficient siRNA delivery system for asthma therapy. Copyright © 2016 Elsevier B.V. All rights reserved.
High-efficiency thin Si solar cells prepared at reduced temperatures. Final report; Herstellung von hocheffizienten, duennen Si-Solarzellen bei erniedrigten Prozesstemperaturen. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Kruehler, W.

1999-07-01

Thin crystalline Si wafer solar cells were processed at reduced temperatures. In addition multicrystalline thin-film solar cells were fabricated on graphite substrates. Large area (175 cm{sup 2}) wafer solar cells made from mono- as well as from tricrystalline Si material were processed with reduced thicknesses down to 100 {mu}m. Conversion efficiencies were obtained in the range between 11.5 and 12.5% without antireflection coating. The reduction of the process temperatures had no positive impact on the expected cost reduction because of the degradation of the electrical cell data during processing. Tricrystalline Si wafers have shown to be mechanically stronger than monocrystalline Si material. Consequently, tri-Si ingots can be sawn in thinner wafers with higher yield. The concept of backside-contacted solar cell was realized by the preparation of thin slit solar cells (150 {mu}m thin, 43 cm{sup 2} in area) made from tri-Si. A conversion efficiency of 14,3% was reached. Amorphous Si layer deposited on graphite substrates were recrystallized by the electron beam recrystallization method developed by the Technical University in Hamburg-Harburg. The recrystallized Si layers showed large grains and were suitible as seed layers for the following gas phase epitaxy (CVD). With the CVD method 20 to 40 {mu}m thin Si absorber layers were deposited on the seed layers with the same excellent crystallographic properties. In contrast, their electrical properties were not sufficient for the preparation of solar cells having more than 3% efficiency. The study of the different concepts has shown, that the development of thin wafer solar cells made from tri-Si has the highest potential with respect to a further cost reduction. (orig.) [German] Es wurden sowohl duenne, kristalline Si-Wafer-Solarzellen bei erniedrigten Prozesstemperaturen als auch multikristalline Si-Duennschicht-Solarzellen auf Graphitsubstraten entwickelt und untersucht. Es konnten grossflaechige (175 cm{sup 2

Growth, characterization and device development in monocrystalline diamond films

Science.gov (United States)

Davis, R. F.; Glass, J. T.; Nemanich, R. J.; Bozeman, S. P.; Sowers, A. T.

1995-06-01

Experimental and theoretical studies concerned with interface interactions of diamond with Si, Ni, and Ni3Si substrates have been conducted. Oriented diamond films deposited on (100) Si were characterized by polar Raman, polar x-ray diffraction (XRD), and cross-sectional high resolution transmission electron microscopy (HRTEM). These sutides showed that the diamond(100)/Si(100) interface adopted the 3:2-match arrangement rather than a 45 deg rotation. Extended Hueckel tight-binding (EHTB) electronic structure calculations for a model system revealed that the interface interaction favors the 3:2-match arrangement. Growth on polycrystalline Ni3Si resulted in oriented diamond particles; under the same growth conditions, graphite was formed on the nickel substrate. Our EHTB electronic structure calculations showed that the (111) and (100) surfaces of Ni3Si have a strong preference for diamond nucleation over graphite nucleation, but this was not the case for the (111) and (100) surfaces of Ni.
Co-delivery of Cbfa-1-targeting siRNA and SOX9 protein using PLGA nanoparticles to induce chondrogenesis of human mesenchymal stem cells.

Science.gov (United States)

Jeon, Su Yeon; Park, Ji Sun; Yang, Han Na; Lim, Hye Jin; Yi, Se Won; Park, Hansoo; Park, Keun-Hong

2014-09-01

During stem cell differentiation, various cellular responses occur that are mediated by transcription factors and proteins. This study evaluated the abilities of SOX9, a crucial protein during the early stage of chondrogenesis, and siRNA targeting Cbfa-1, a transcription factor that promotes osteogenesis, to stimulate chondrogenesis. Non-toxic poly-(d,l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) were coated with Cbfa-1-targeting siRNA and loaded with SOX9 protein. Coomassie blue staining and circular dichroism revealed that the loaded SOX9 protein maintained its stability and bioactivity. These NPs easily entered human mesenchymal stem cells (hMSCs) in vitro and caused them to differentiate into chondrocytes. Markers that are typically expressed in mature chondrocytes were examined. These markers were highly expressed at the mRNA and protein levels in hMSCs treated with PLGA NPs coated with Cbfa-1-targeting siRNA and loaded with SOX9 protein. By contrast, these cells did not express osteogenesis-related markers. hMSCs were injected into mice following internalization of PLGA NPs coated with Cbfa-1-targeting siRNA and loaded with SOX9 protein. When the injection site was excised, markers of chondrogenesis were found to be highly expressed at the mRNA and protein levels, similar to the in vitro results. When hMSCs internalized these NPs and were then cultured in vitro or injected into mice, chondrogenesis-related extracellular matrix components were highly expressed. Copyright © 2014 Elsevier Ltd. All rights reserved.
CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

KAUST Repository

Ghoneim, Mohamed T.; Hanna, Amir; Hussain, Muhammad Mustafa

2014-01-01

Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.
CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

KAUST Repository

Ghoneim, Mohamed T.

2014-08-01

Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.
A novel strategy to increase separated electron-hole dipoles in commercial Si based solar panel to assist photovoltaic effect

Science.gov (United States)

Feng, Yefeng; He, Cheng-En; Xu, Zhichao; Hu, Jianbing; Peng, Cheng

2018-01-01

Interface induced polarization has been found to have a significant impact on dielectric properties of 2-2 type polymer composites bearing Si based semi-conducting ceramic sheets. Inherent overall polarity of polymer layers in 2-2 composites has been verified to be closely connected with interface effect and achieved permittivity in composites. In present work, conducting performances of monocrystalline Si sheets coated by varied high polarity material layers were deeply researched. The positive results inspired us to propose a novel strategy to improve separated electron-hole dipoles in commercial Si based solar cell panel for assisting photovoltaic effect, based on strong interface induced polarization. Conducting features of solar panels coated by two different high polarity polymer layers were detected to be greatly elevated compared with solar panel standalone, thanks to interface induced polarization between panel and polymer. Polymer coating with higher polarity would lead to more separated electron-hole dipole pairs in solar panel contributing to higher conductivity of panel. Valid synergy of interface effect and photovoltaic effect was based on their unidirectional traits of electron transfer. Dielectric properties of solar panels in composites further confirmed that strategy. This work might provide a facile route to prepare promising Si based solar panels with higher photoelectric conversion efficiency by enhancing interface induced polarization between panel and polymer coating.
Ni-Si oxide as an inducing crystallization source for making poly-Si

Energy Technology Data Exchange (ETDEWEB)

Meng, Zhiguo; Liu, Zhaojun; Li, Juan; Wu, Chunya; Xiong, Shaozhen [Institute of Photo-electronics, Nankai University, Tianjin (China); Zhao, Shuyun; Wong, Man; Kwok, Hoi Sing [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong (China)

2010-04-15

Nickel silicon oxide mixture was sputtered on a-Si with Ni-Si alloy target with Ni:Si weight ratio of 1:9 and used as a new inducing source for metal induced lateral crystallization (MILC). The characteristics of the resulted poly-Si materials induced by Ni-Si oxide with different thickness were nearly the same. This means the metal induced crystallization with this new inducing source has wide processing tolerance to make MILC poly-Si. Besides, it reduced the residual Ni content in the resulted poly-Si film. The transfer characteristic curve of poly-Si TFT and a TFT-OLED display demo made with this kind of new inducing source were also presented in this paper. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Self-assembled nanoparticles based on the c(RGDfk peptide for the delivery of siRNA targeting the VEGFR2 gene for tumor therapy

Directory of Open Access Journals (Sweden)

Liu L

2014-07-01

Full Text Available Li Liu,1 Xiaoxia Liu,1 Qian Xu,1 Ping Wu,2 Xialin Zuo,3 Jingjing Zhang,1 Houliang Deng,1 Zhuomin Wu,1 Aimin Ji1 1Department of Pharmacy, Zhujiang Hospital, Southern Medical University, Guangzhou, People’s Republic of China; 2Department of Pharmacy, Chengdu Integrated TCM & Western Medicine Hospital, Chengdu, People’s Republic of China; 3Institute of Neurosciences and the Second Affiliated Hospital of Guangzhou Medical University, Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou, People’s Republic of China Abstract: The clinical application of small interfering RNA (siRNA has been restricted by their poor intracellular uptake, low serum stability, and inability to target specific cells. During the last several decades, a great deal of effort has been devoted to exploring materials for siRNA delivery. In this study, biodegradable, tumor-targeted, self-assembled peptide nanoparticles consisting of cyclo(Arg–Gly–Asp–d–Phe–Lys-8–amino–3,6–dioxaoctanoic acid–β–maleimidopropionic acid (hereafter referred to as RPM were found to be an effective siRNA carrier both in vitro and in vivo. The nanoparticles were characterized based on transmission electron microscopy, circular dichroism spectra, and dynamic light scattering. In vitro analyses showed that the RPM/VEGFR2-siRNA exhibited negligible cytotoxicity and induced effective gene silencing. Delivery of the RPM/VEGFR2 (zebrafish-siRNA into zebrafish embryos resulted in inhibition of neovascularization. Administration of RPM/VEGFR2 (mouse-siRNA to tumor-bearing nude mice led to a significant inhibition of tumor growth, a marked reduction of vessels, and a downregulation of VEGFR2 (messenger RNA and protein in tumor tissue. Furthermore, the levels of IFN-α, IFN-γ, IL-12, and IL-6 in mouse serum, assayed via enzyme-linked immunosorbent assay, did not indicate any immunogenicity of the RPM/VEGFR2 (mouse-si
HIVsirDB: a database of HIV inhibiting siRNAs.

Directory of Open Access Journals (Sweden)

Atul Tyagi

Full Text Available Human immunodeficiency virus (HIV is responsible for millions of deaths every year. The current treatment involves the use of multiple antiretroviral agents that may harm patients due to their toxic nature. RNA interference (RNAi is a potent candidate for the future treatment of HIV, uses short interfering RNA (siRNA/shRNA for silencing HIV genes. In this study, attempts have been made to create a database HIVsirDB of siRNAs responsible for silencing HIV genes.HIVsirDB is a manually curated database of HIV inhibiting siRNAs that provides comprehensive information about each siRNA or shRNA. Information was collected and compiled from literature and public resources. This database contains around 750 siRNAs that includes 75 partially complementary siRNAs differing by one or more bases with the target sites and over 100 escape mutant sequences. HIVsirDB structure contains sixteen fields including siRNA sequence, HIV strain, targeted genome region, efficacy and conservation of target sequences. In order to facilitate user, many tools have been integrated in this database that includes; i siRNAmap for mapping siRNAs on target sequence, ii HIVsirblast for BLAST search against database, iii siRNAalign for aligning siRNAs.HIVsirDB is a freely accessible database of siRNAs which can silence or degrade HIV genes. It covers 26 types of HIV strains and 28 cell types. This database will be very useful for developing models for predicting efficacy of HIV inhibiting siRNAs. In summary this is a useful resource for researchers working in the field of siRNA based HIV therapy. HIVsirDB database is accessible at http://crdd.osdd.net/raghava/hivsir/.
Efficient construction of an inverted minimal H1 promoter driven siRNA expression cassette: facilitation of promoter and siRNA sequence exchange.

Directory of Open Access Journals (Sweden)

Hoorig Nassanian

2007-08-01

Full Text Available RNA interference (RNAi, mediated by small interfering RNA (siRNA, is an effective method used to silence gene expression at the post-transcriptional level. Upon introduction into target cells, siRNAs incorporate into the RNA-induced silencing complex (RISC. The antisense strand of the siRNA duplex then "guides" the RISC to the homologous mRNA, leading to target degradation and gene silencing. In recent years, various vector-based siRNA expression systems have been developed which utilize opposing polymerase III promoters to independently drive expression of the sense and antisense strands of the siRNA duplex from the same template.We show here the use of a ligase chain reaction (LCR to develop a new vector system called pInv-H1 in which a DNA sequence encoding a specific siRNA is placed between two inverted minimal human H1 promoters (approximately 100 bp each. Expression of functional siRNAs from this construct has led to efficient silencing of both reporter and endogenous genes. Furthermore, the inverted H1 promoter-siRNA expression cassette was used to generate a retrovirus vector capable of transducing and silencing expression of the targeted protein by>80% in target cells.The unique design of this construct allows for the efficient exchange of siRNA sequences by the directional cloning of short oligonucleotides via asymmetric restriction sites. This provides a convenient way to test the functionality of different siRNA sequences. Delivery of the siRNA cassette by retroviral transduction suggests that a single copy of the siRNA expression cassette efficiently knocks down gene expression at the protein level. We note that this vector system can potentially be used to generate a random siRNA library. The flexibility of the ligase chain reaction suggests that additional control elements can easily be introduced into this siRNA expression cassette.
Study of intermittency of target fragments in the interactions of 28Si-Em collisions at 14.6 A GeV

International Nuclear Information System (INIS)

Ayaz Ahmad, M.; Ashraf T, M.; Ahmad, Shafiq

2008-01-01

An attempt has been made to investigate the intermittent behaviour and fractal properties of emission spectra of fast and slow target associated particles from 28 Si-emulsion interactions at 14.6 A GeV using nuclear emulsion in cosθ phase space
Combinatorial study of low-refractive Mg-F-Si-O nano-composites deposited by magnetron co-sputtering from compound targets

Science.gov (United States)

Mertin, Stefan; Länzlinger, Tony; Sandu, Cosmin S.; Scartezzini, Jean-Louis; Muralt, Paul

2018-03-01

Deposition of nano-composite Mg-F-Si-O films on optical grade silica glass was studied employing RF magnetron co-sputtering from magnesium fluoride (MgF2) and fused silica (SiO2) targets. The aim was to obtain a stable and reliable sputtering process for optical coatings exhibiting a refractive index lower than the one of quartz glass (1.46 at 550 nm) without adding gaseous fluorine to the deposition process. The two magnetrons were installed in a confocal way at 45° off-axis with respect to a static substrate, thus creating a lateral gradient in the thin-film composition. The deposited Mg-F-Si-O coatings were structurally analysed by electron dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The obtained films consist of MgF2 nanocrystals embedded in a SiO2-rich amorphous matrix. Spectroscopic ellipsometry and spectrophotometry measurements showed that they are highly transparent exhibiting a very-low extinction coefficient k and a refractive index n in the desired range between the one of MgF2 (1.38) and SiO2 (1.46). Films with n = 1.424 and 1.435 at 550 nm were accomplished with absorption below the detection threshold.
Inhibition of Glomerular Mesangial Cell Proliferation by siPDGF-B- and siPDGFR-β-Containing Chitosan Nanoplexes.

Science.gov (United States)

Salva, Emine; Turan, Suna Özbaş; Akbuğa, Jülide

2017-05-01

Mesangioproliferative glomerulonephritis is a disease that has a high incidence in humans. In this disease, the proliferation of glomerular mesangial cells and the production of extracellular matrix are important. In recent years, the RNAi technology has been widely used in the treatment of various diseases due to its capability to inhibit the gene expression with high specificity and targeting. The objective of this study was to decrease mesangial cell proliferation by knocking down PDGF-B and its receptor, PDGFR-β. To be able to use small interfering RNAs (siRNAs) in the treatment of this disease successfully, it is necessary to develop appropriate delivery systems. Chitosan, which is a biopolymer, is used as a siRNA delivery system in kidney drug targeting. In order to deliver siRNA molecules targeted at PDGF-B and PDGFR-β, chitosan/siRNA nanoplexes were prepared. The in vitro characterization, transfection studies, and knockdown efficiencies were studied in immortalized and primary rat mesangial cells. In addition, the effects of chitosan nanoplexes on mesangial cell proliferation and migration were investigated. After in vitro transfection, the PDGF-B and PDGFR-β gene silencing efficiencies of PDGF-B and PDGFR-β targeting siRNA-containing chitosan nanoplexes were 74 and 71% in immortalized rat mesangial cells and 66 and 62% in primary rat mesangial cells, respectively. siPDGF-B- and siPDGFR-β-containing nanoplexes indicated a significant decrease in mesangial cell migration and proliferation. These results suggested that mesangial cell proliferation may be inhibited by silencing of the PDGF-B signaling pathway. Gene silencing approaches with chitosan-based gene delivery systems have promise for the efficient treatment of renal disease.
siRNAmod: A database of experimentally validated chemically modified siRNAs.

Science.gov (United States)

Dar, Showkat Ahmad; Thakur, Anamika; Qureshi, Abid; Kumar, Manoj

2016-01-28

Small interfering RNA (siRNA) technology has vast potential for functional genomics and development of therapeutics. However, it faces many obstacles predominantly instability of siRNAs due to nuclease digestion and subsequently biologically short half-life. Chemical modifications in siRNAs provide means to overcome these shortcomings and improve their stability and potency. Despite enormous utility bioinformatics resource of these chemically modified siRNAs (cm-siRNAs) is lacking. Therefore, we have developed siRNAmod, a specialized databank for chemically modified siRNAs. Currently, our repository contains a total of 4894 chemically modified-siRNA sequences, comprising 128 unique chemical modifications on different positions with various permutations and combinations. It incorporates important information on siRNA sequence, chemical modification, their number and respective position, structure, simplified molecular input line entry system canonical (SMILES), efficacy of modified siRNA, target gene, cell line, experimental methods, reference etc. It is developed and hosted using Linux Apache MySQL PHP (LAMP) software bundle. Standard user-friendly browse, search facility and analysis tools are also integrated. It would assist in understanding the effect of chemical modifications and further development of stable and efficacious siRNAs for research as well as therapeutics. siRNAmod is freely available at: http://crdd.osdd.net/servers/sirnamod.
Measurement of proton induced thick target γ-ray yields on B, N, Na, Al and Si from 2.5 to 4.1 MeV

Energy Technology Data Exchange (ETDEWEB)

Chiari, M., E-mail: chiari@fi.infn.it [INFN-Florence and Department of Physics and Astronomy, University of Florence, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Ferraccioli, G.; Melon, B.; Nannini, A.; Perego, A.; Salvestrini, L. [INFN-Florence and Department of Physics and Astronomy, University of Florence, via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Lagoyannis, A.; Preketes-Sigalas, K. [Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics, NCSR “Demokritos”, 153.10 Aghia Paraskevi, Athens (Greece)

2016-01-01

Thick target yields for proton induced γ-ray emission (PIGE) on low-Z nuclei, namely B, N, Na, Al and Si, were measured for proton energies from 2.5 to 4.1 MeV and emission angles of 0°, 45° and 90°, at the 3 MV Tandetron laboratory of INFN-LABEC in Florence. The studied reactions were: {sup 10}B(p,α′γ){sup 7}Be (E{sub γ} = 429 keV), {sup 10}B(p,p′γ){sup 10}B (E{sub γ} = 718 keV) and {sup 11}B(p,p′γ){sup 11}B (E{sub γ} = 2125 keV) for boron; {sup 14}N(p,p′γ){sup 14}N (E{sub γ} = 2313 keV) for nitrogen; {sup 23}Na(p,p′γ){sup 23}Na (E{sub γ} = 441 and 1636 keV) and {sup 23}Na(p,α′γ){sup 20}Ne (E{sub γ} = 1634 keV) for sodium; {sup 27}Al(p,p′γ){sup 27}Al (E{sub γ} = 844 and 1014 keV) and {sup 27}Al(p,α′γ){sup 24}Mg (E{sub γ} = 1369 keV) for aluminum; {sup 28}Si(p,p′γ){sup 28}Si (E{sub γ} = 1779 keV) and {sup 29}Si(p,p′γ){sup 29}Si (E{sub γ} = 1273 keV) for silicon. The PIGE thick target yields have been measured with an overall uncertainty typically better than 10%. The use of the measured thick target yield to benchmark and validate experimental cross sections available in the literature is demonstrated.
Device-based local delivery of siRNA against mammalian target of rapamycin (mTOR) in a murine subcutaneous implant model to inhibit fibrous encapsulation.

Science.gov (United States)

Takahashi, Hironobu; Wang, Yuwei; Grainger, David W

2010-11-01

Fibrous encapsulation of surgically implanted devices is associated with elevated proliferation and activation of fibroblasts in tissues surrounding these implants, frequently causing foreign body complications. Here we test the hypothesis that inhibition of the expression of mammalian target of rapamycin (mTOR) in fibroblasts can mitigate the soft tissue implant foreign body response by suppressing fibrotic responses around implants. In this study, mTOR was knocked down using small interfering RNA (siRNA) conjugated with branched polyethylenimine (bPEI) in fibroblastic lineage cells in serum-based cell culture as shown by both gene and protein analysis. This mTOR knock-down led to an inhibition in fibroblast proliferation by 70% and simultaneous down-regulation in the expression of type I collagen in fibroblasts in vitro. These siRNA/bPEI complexes were released from poly(ethylene glycol) (PEG)-based hydrogel coatings surrounding model polymer implants in a subcutaneous rodent model in vivo. No significant reduction in fibrous capsule thickness and mTOR expression in the foreign body capsules were observed. The siRNA inefficacy in this in vivo implant model was attributed to siRNA dosing limitations in the gel delivery system, and lack of targeting ability of the siRNA complex specifically to fibroblasts. While in vitro data supported mTOR knock-down in fibroblast cultures, in vivo siRNA delivery must be further improved to produce clinically relevant effects on fibrotic encapsulation around implants. Copyright © 2010 Elsevier B.V. All rights reserved.
New insights into siRNA amplification and RNAi.

Science.gov (United States)

Zhang, Chi; Ruvkun, Gary

2012-08-01

In the nematode Caenorhabditis elegans (C. elegans), gene inactivation by RNA interference can achieve remarkable potency due to the amplification of initial silencing triggers by RNA-dependent RNA polymerases (RdRPs). RdRPs catalyze the biogenesis of an abundant species of secondary small interfering RNAs (siRNAs) using the target mRNA as template. The interaction between primary siRNAs derived from the exogenous double-stranded RNA (dsRNA) trigger and the target mRNA is required for the recruitment of RdRPs. Other genetic requirements for RdRP activities have not been characterized. Recent studies have identified the RDE-10/RDE-11 complex which interacts with the primary siRNA bound target mRNA and acts upstream of the RdRPs. rde-10 and rde-11 mutants show an RNAi defective phenotype because the biogenesis of secondary siRNAs is completely abolished. In addition, the RDE-10/RDE-11 complex plays a similar role in the endogenous RNAi pathway for the biogenesis of a subset of siRNAs targeting recently acquired, duplicated genes.
VRP09 Reduction of Corneal Scarring Following Blast and Burn Injuries to Cornea Using siRNAs Targeting TGFb and CTGF

Science.gov (United States)

2013-03-01

aSMA ) synthesis. Second, we proposed to develop an advanced ex vivo organ culture system using viable explants of rabbit corneas, and assess the...effect of the most effective triple siRNA combination for reduction of target genes, collagen and alpha smooth muscle actin ( aSMA ) in rabbit corneas...targeting three key genes (TGFb, TGFbRII, and CTGF) that synergistically reduces the level of mRNAs for type I collagen gene and aSMA by >95% without
Electromagnetic dissociation of relativistic [sup 28]Si by nucleon emission

Energy Technology Data Exchange (ETDEWEB)

Sonnadara, U.J.

1992-12-01

A detailed study of the electromagnetic dissociation of [sup 28]Si by nucleon emission at E[sub lab]/A = 14.6 (GeV/nucleon was carried out with [sup 28]Si beams interacting on [sup 208]Pb). [sup 120]Sn. [sup 64]C targets. The measurements apparatus consists of detectors in the target area which measure the energy and charged multiplicity, and a forward spectrometer which measures the position, momentum and energy of the reaction fragments. The exclusive electromagnetic dissociation cross sections for decay channels having multiple nucleons in the final state have been measured which enables the selection of events produced in pure electromagnetic interactions. The measured cross sections agree well with previous measurements obtained for the removal of a few nucleons as well as with measurements on total charge removal cross sections from other experiments. The dependence of the integrated cross sections on the target charge Z[sub T] and the target mass AT confirms that for higher Z targets the excitation is largely electromagnetic. Direct measurements of the excitation energy for the electromagnetic dissociation of [sup 28]Si [yields] p+[sup 27]Al and [sup 28]Si [yields] n+[sup 27]Si have been obtained through a calculation of the invariant mass in kinematically, reconstructed events. The excitation energy spectrum for all targets peak near the isovector giant dipole resonance in [sup 28]Si. These distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear [sup 28]Si([sub [gamma],p])[sup 27]Al and [sup 28]Si([sub [gamma],n])[sup 27]Si. The possibilities of observing double giant dipole resonance excitations in [sup 28]Si have been investigated with cross section measurements as well as with excitation energy reconstruction.
Corrugation Architecture Enabled Ultraflexible Wafer-Scale High-Efficiency Monocrystalline Silicon Solar Cell

KAUST Repository

Bahabry, Rabab R.

2018-01-02

Advanced classes of modern application require new generation of versatile solar cells showcasing extreme mechanical resilience, large-scale, low cost, and excellent power conversion efficiency. Conventional crystalline silicon-based solar cells offer one of the most highly efficient power sources, but a key challenge remains to attain mechanical resilience while preserving electrical performance. A complementary metal oxide semiconductor-based integration strategy where corrugation architecture enables ultraflexible and low-cost solar cell modules from bulk monocrystalline large-scale (127 × 127 cm) silicon solar wafers with a 17% power conversion efficiency. This periodic corrugated array benefits from an interchangeable solar cell segmentation scheme which preserves the active silicon thickness of 240 μm and achieves flexibility via interdigitated back contacts. These cells can reversibly withstand high mechanical stress and can be deformed to zigzag and bifacial modules. These corrugation silicon-based solar cells offer ultraflexibility with high stability over 1000 bending cycles including convex and concave bending to broaden the application spectrum. Finally, the smallest bending radius of curvature lower than 140 μm of the back contacts is shown that carries the solar cells segments.
Corrugation Architecture Enabled Ultraflexible Wafer-Scale High-Efficiency Monocrystalline Silicon Solar Cell

KAUST Repository

Bahabry, Rabab R.; Kutbee, Arwa T.; Khan, Sherjeel M.; Sepulveda, Adrian C.; Wicaksono, Irmandy; Nour, Maha A.; Wehbe, Nimer; Almislem, Amani Saleh Saad; Ghoneim, Mohamed T.; Sevilla, Galo T.; Syed, Ahad; Shaikh, Sohail F.; Hussain, Muhammad Mustafa

2018-01-01

Advanced classes of modern application require new generation of versatile solar cells showcasing extreme mechanical resilience, large-scale, low cost, and excellent power conversion efficiency. Conventional crystalline silicon-based solar cells offer one of the most highly efficient power sources, but a key challenge remains to attain mechanical resilience while preserving electrical performance. A complementary metal oxide semiconductor-based integration strategy where corrugation architecture enables ultraflexible and low-cost solar cell modules from bulk monocrystalline large-scale (127 × 127 cm) silicon solar wafers with a 17% power conversion efficiency. This periodic corrugated array benefits from an interchangeable solar cell segmentation scheme which preserves the active silicon thickness of 240 μm and achieves flexibility via interdigitated back contacts. These cells can reversibly withstand high mechanical stress and can be deformed to zigzag and bifacial modules. These corrugation silicon-based solar cells offer ultraflexibility with high stability over 1000 bending cycles including convex and concave bending to broaden the application spectrum. Finally, the smallest bending radius of curvature lower than 140 μm of the back contacts is shown that carries the solar cells segments.

Effective silencing of ENaC by siRNA delivered with epithelial-targeted nanocomplexes in human cystic fibrosis cells and in mouse lung.

Science.gov (United States)

Tagalakis, Aristides D; Munye, Mustafa M; Ivanova, Rositsa; Chen, Hanpeng; Smith, Claire M; Aldossary, Ahmad M; Rosa, Luca Z; Moulding, Dale; Barnes, Josephine L; Kafetzis, Konstantinos N; Jones, Stuart A; Baines, Deborah L; Moss, Guy W J; O'Callaghan, Christopher; McAnulty, Robin J; Hart, Stephen L

2018-05-10

Loss of the cystic fibrosis transmembrane conductance regulator in cystic fibrosis (CF) leads to hyperabsorption of sodium and fluid from the airway due to upregulation of the epithelial sodium channel (ENaC). Thickened mucus and depleted airway surface liquid (ASL) then lead to impaired mucociliary clearance. ENaC regulation is thus a promising target for CF therapy. Our aim was to develop siRNA nanocomplexes that mediate effective silencing of airway epithelial ENaC in vitro and in vivo with functional correction of epithelial ion and fluid transport. We investigated translocation of nanocomplexes through mucus and their transfection efficiency in primary CF epithelial cells grown at air-liquid interface (ALI).Short interfering RNA (SiRNA)-mediated silencing was examined by quantitative RT-PCR and western analysis of ENaC. Transepithelial potential (V t ), short circuit current (I sc ), ASL depth and ciliary beat frequency (CBF) were measured for functional analysis. Inflammation was analysed by histological analysis of normal mouse lung tissue sections. Nanocomplexes translocated more rapidly than siRNA alone through mucus. Transfections of primary CF epithelial cells with nanocomplexes targeting αENaC siRNA, reduced αENaC and βENaC mRNA by 30%. Transfections reduced V t , the amiloride-sensitive I sc and mucus protein concentration while increasing ASL depth and CBF to normal levels. A single dose of siRNA in mouse lung silenced ENaC by approximately 30%, which persisted for at least 7 days. Three doses of siRNA increased silencing to approximately 50%. Nanoparticle-mediated delivery of ENaCsiRNA to ALI cultures corrected aspects of the mucociliary defect in human CF cells and offers effective delivery and silencing in vivo. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Crystal Orientation Effect on the Subsurface Deformation of Monocrystalline Germanium in Nanometric Cutting.

Science.gov (United States)

Lai, Min; Zhang, Xiaodong; Fang, Fengzhou

2017-12-01

Molecular dynamics simulations of nanometric cutting on monocrystalline germanium are conducted to investigate the subsurface deformation during and after nanometric cutting. The continuous random network model of amorphous germanium is established by molecular dynamics simulation, and its characteristic parameters are extracted to compare with those of the machined deformed layer. The coordination number distribution and radial distribution function (RDF) show that the machined surface presents the similar amorphous state. The anisotropic subsurface deformation is studied by nanometric cutting on the (010), (101), and (111) crystal planes of germanium, respectively. The deformed structures are prone to extend along the 110 slip system, which leads to the difference in the shape and thickness of the deformed layer on various directions and crystal planes. On machined surface, the greater thickness of subsurface deformed layer induces the greater surface recovery height. In order to get the critical thickness limit of deformed layer on machined surface of germanium, the optimized cutting direction on each crystal plane is suggested according to the relevance of the nanometric cutting to the nanoindentation.
Electrical analysis of high dielectric constant insulator and metal gate metal oxide semiconductor capacitors on flexible bulk mono-crystalline silicon

KAUST Repository

Ghoneim, Mohamed T.

2015-06-01

We report on the electrical study of high dielectric constant insulator and metal gate metal oxide semiconductor capacitors (MOSCAPs) on a flexible ultra-thin (25 μm) silicon fabric which is peeled off using a CMOS compatible process from a standard bulk mono-crystalline silicon substrate. A lifetime projection is extracted using statistical analysis of the ramping voltage (Vramp) breakdown and time dependent dielectric breakdown data. The obtained flexible MOSCAPs operational voltages satisfying the 10 years lifetime benchmark are compared to those of the control MOSCAPs, which are not peeled off from the silicon wafer. © 2014 IEEE.
Detection of siRNA Mediated Target mRNA Cleavage Activities in Human Cells by a Novel Stem-Loop Array RT-PCR Analysis

Science.gov (United States)

2016-09-07

sequences of the target mRNA, and a double stranded stem at the 5′ end that forms a stem -loop to function as a forceps to stabilize the secondary...E-mjournal homepage: www.elsevier.com/locate/bbrepDetection of siRNA-mediated target mRNA cleavage activities in human cells by a novel stem -loop...challenges for the accurate and efficient detection and verification of cleavage sites on target mRNAs. Here we used a sensitive stem -loop array reverse
Synthesis of PLGA-Lipid Hybrid Nanoparticles for siRNA Delivery Using the Emulsion Method PLGA-PEG-Lipid Nanoparticles for siRNA Delivery.

Science.gov (United States)

Wang, Lei; Griffel, Benjamin; Xu, Xiaoyang

2017-01-01

The effective delivery of small interfering RNA (siRNA) to tumor cells remains a challenge for applications in cancer therapy. The development of polymeric nanoparticles with high siRNA loading efficacy has shown great potential for cancer targets. Double emulsion solvent evaporation technique is a useful tool for encapsulation of hydrophilic molecules (e.g., siRNA). Here we describe a versatile platform for siRNA delivery based on PLGA-PEG-cationic lipid nanoparticles by using the double emulsion method. The resulting nanoparticles show high encapsulation efficiency for siRNA (up to 90%) and demonstrate effective downregulation of the target genes in vitro and vivo.
Tailoring Lipid and Polymeric Nanoparticles as siRNA Carriers towards the Blood-Brain Barrier - from Targeting to Safe Administration.

Science.gov (United States)

Gomes, Maria João; Fernandes, Carlos; Martins, Susana; Borges, Fernanda; Sarmento, Bruno

2017-03-01

Blood-brain barrier is a tightly packed layer of endothelial cells surrounding the brain that acts as the main obstacle for drugs enter the central nervous system (CNS), due to its unique features, as tight junctions and drug efflux systems. Therefore, since the incidence of CNS disorders is increasing worldwide, medical therapeutics need to be improved. Consequently, aiming to surpass blood-brain barrier and overcome CNS disabilities, silencing P-glycoprotein as a drug efflux transporter at brain endothelial cells through siRNA is considered a promising approach. For siRNA enzymatic protection and efficient delivery to its target, two different nanoparticles platforms, solid lipid (SLN) and poly-lactic-co-glycolic (PLGA) nanoparticles were used in this study. Polymeric PLGA nanoparticles were around 115 nm in size and had 50 % of siRNA association efficiency, while SLN presented 150 nm and association efficiency close to 52 %. Their surface was functionalized with a peptide-binding transferrin receptor, in a site-oriented manner confirmed by NMR, and their targeting ability against human brain endothelial cells was successfully demonstrated by fluorescence microscopy and flow cytometry. The interaction of modified nanoparticles with brain endothelial cells increased 3-fold compared to non-modified lipid nanoparticles, and 4-fold compared to non-modified PLGA nanoparticles, respectively. These nanosystems, which were also demonstrated to be safe for human brain endothelial cells, without significant cytotoxicity, bring a new hopeful breath to the future of brain diseases therapies.
Reduced-pressure chemical vapor deposition of boron-doped Si and Ge layers

International Nuclear Information System (INIS)

Bogumilowicz, Y.; Hartmann, J.M.

2014-01-01

We have studied the in-situ boron (B) doping of germanium (Ge) and silicon (Si) in Reduced Pressure-Chemical Vapor Deposition. Three growth temperatures have been investigated for the B-doping of Ge: 400, 600 and 750 °C at a constant growth pressure of 13300 Pa (i.e. 100 Torr). The B concentration in the Ge:B epilayer increases linearly with the diborane concentration in the gaseous phase. Single-crystalline Ge:B layers with B concentrations in-between 9 ∙ 10 17 and 1 ∙ 10 20 cm −3 were achieved. For the in-situ B doping of Si at 850 °C, two dichlorosilane mass flow ratios (MFR) have been assessed: F[SiH 2 Cl 2 ]/F[H 2 ] = 0.0025 and F[SiH 2 Cl 2 ]/F[H 2 ] = 0.0113 at a growth pressure of 2660 Pa (i.e. 20 Torr). Linear boron incorporation with the diborane concentration in the gas phase has been observed and doping levels in-between 3.5 ∙ 10 17 and 1 ∙ 10 20 cm −3 were achieved. We almost kept the same ratio of B versus Si atoms in the gas phase and in the Si epilayer. By contrast, roughly half of the B atoms present in the gas phase were incorporated in the Ge:B layers irrespective of the growth temperature. X-Ray Diffraction (XRD) allowed us to extract from the angular position of the Ge:B layer diffraction peak the substitutional B concentration. Values close to the B concentrations obtained by 4-probe resistivity measurements were obtained. Ge:B layers were smooth (< 1 m root mean square roughness associated with 20 × 20 μm 2 Atomic Force Microscopy images). Only for high F[B 2 H 6 ]/F[GeH 4 ] MFR (3.2 10 −3 ) did the Ge:B layers became rough; they were however still mono-crystalline (XRD). Above this MFR value, Ge:B layers became polycrystalline. - Highlights: • Boron doping of germanium and silicon in Reduced Pressure-Chemical Vapor Deposition • Linear boron incorporation in Ge:B and Si:B with the diborane flow • Single-crystal Ge:B layers with B concentrations in-between 9 ∙ 10 17 and 1 ∙ 10 20 cm −3 • Single-crystal Si
Sticky siRNAs targeting survivin and cyclin B1 exert an antitumoral effect on melanoma subcutaneous xenografts and lung metastases

International Nuclear Information System (INIS)

Kedinger, Valerie; Erbacher, Patrick; Bolcato-Bellemin, Anne-Laure; Meulle, Aline; Zounib, Omar; Bonnet, Marie-Elise; Gossart, Jean-Baptiste; Benoit, Elodie; Messmer, Melanie; Shankaranarayanan, Pattabhiraman; Behr, Jean-Paul

2013-01-01

Melanoma represents one of the most aggressive and therapeutically challenging malignancies as it often gives rise to metastases and develops resistance to classical chemotherapeutic agents. Although diverse therapies have been generated, no major improvement of the patient prognosis has been noticed. One promising alternative to the conventional therapeutic approaches currently available is the inactivation of proteins essential for survival and/or progression of melanomas by means of RNA interference. Survivin and cyclin B1, both involved in cell survival and proliferation and frequently deregulated in human cancers, are good candidate target genes for siRNA mediated therapeutics. We used our newly developed sticky siRNA-based technology delivered with linear polyethyleneimine (PEI) to inhibit the expression of survivin and cyclin B1 both in vitro and in vivo, and addressed the effect of this inhibition on B16-F10 murine melanoma tumor development. We confirm that survivin and cyclin B1 downregulation through a RNA interference mechanism induces a blockage of the cell cycle as well as impaired proliferation of B16-F10 cells in vitro. Most importantly, PEI-mediated systemic delivery of sticky siRNAs against survivin and cyclin B1 efficiently blocks growth of established subcutaneaous B16-F10 tumors as well as formation and dissemination of melanoma lung metastases. In addition, we highlight that inhibition of survivin expression increases the effect of doxorubicin on lung B16-F10 metastasis growth inhibition. PEI-mediated delivery of sticky siRNAs targeting genes involved in tumor progression such as survivin and cyclin B1, either alone or in combination with chemotherapeutic drugs, represents a promising strategy for melanoma treatment
Nanostructured Si-substituted hydroxyapatite coatings for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Rau, Julietta V., E-mail: giulietta.rau@ism.cnr.it [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Fosca, Marco [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Cacciotti, Ilaria [Università di Roma “Tor Vergata”, Dipartimento di Ingegneria Industriale,UR INSTM “Roma Tor Vergata”, Via del Politecnico, 1-00133 Rome (Italy); Laureti, Sara [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via Salaria km 29.300-00016 Monterotondo Scalo (RM) (Italy); Bianco, Alessandra [Università di Roma “Tor Vergata”, Dipartimento di Ingegneria Industriale,UR INSTM “Roma Tor Vergata”, Via del Politecnico, 1-00133 Rome (Italy); Teghil, Roberto [Università della Basilicata, Dipartimento di Scienze, Via dell' Ateneo Lucano 10-85100, Potenza (Italy)

2013-09-30

In the present work, the Si-HAp coatings were deposited on titanium substrates by Pulsed Laser Deposition technique. For deposition, the Si-HAp targets (1.4 wt.% of Si), produced starting from wet synthesized powders, were used. The properties of coatings were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and Vickers microhardness. The obtained Si-HAp coatings presented a nanosized structure, proper thickness and hardness for applications in orthopedical and dental surgery, aimed at improving the stability and the osteointegration of bone implants. - Highlights: ► Pulsed Laser Deposition method was applied to coat heated Titanium supports. ► Films were deposited using a target of Silicon-Hydroxyapatite sintered ceramics. ► Nanostructured crystalline hard film was grown replicating target composition. ► Prepared coating could be used for orthopedic and dental implants applications.
Nanostructured Si-substituted hydroxyapatite coatings for biomedical applications

International Nuclear Information System (INIS)

Rau, Julietta V.; Fosca, Marco; Cacciotti, Ilaria; Laureti, Sara; Bianco, Alessandra; Teghil, Roberto

2013-01-01

In the present work, the Si-HAp coatings were deposited on titanium substrates by Pulsed Laser Deposition technique. For deposition, the Si-HAp targets (1.4 wt.% of Si), produced starting from wet synthesized powders, were used. The properties of coatings were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and Vickers microhardness. The obtained Si-HAp coatings presented a nanosized structure, proper thickness and hardness for applications in orthopedical and dental surgery, aimed at improving the stability and the osteointegration of bone implants. - Highlights: ► Pulsed Laser Deposition method was applied to coat heated Titanium supports. ► Films were deposited using a target of Silicon-Hydroxyapatite sintered ceramics. ► Nanostructured crystalline hard film was grown replicating target composition. ► Prepared coating could be used for orthopedic and dental implants applications
Formation of Monocrystalline 1D and 2D Architectures via Epitaxial Attachment: Bottom-Up Routes through Surfactant-Mediated Arrays of Oriented Nanocrystals.

Science.gov (United States)

Nakagawa, Yoshitaka; Kageyama, Hiroyuki; Oaki, Yuya; Imai, Hiroaki

2015-06-09

Monocrystalline architectures with well-defined shapes were achieved by bottom-up routes through epitaxial attachment of Mn3O4 nanocrystals. The crystallographically continuous 1D chains elongated in the a axis and 2D panels having large a or c faces were obtained by removal of the organic mediator from surfactant-mediated 1D and 2D arrays of Mn3O4 nanocrystals, respectively. Our basal approach indicates that the epitaxial attachment through the surfactant-mediated arrays is utilized for fabrication of a wide variety of micrometric architectures from nanometric crystalline units.
Fabrication of core-shell nanostructures via silicon on insulator dewetting and germanium condensation: towards a strain tuning method for SiGe-based heterostructures in a three-dimensional geometry.

Science.gov (United States)

Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Cabie, Martiane; Ronda, Antoine; Berbezier, Isabelle; Abbarchi, Marco

2016-07-29

We report on a novel method for the implementation of core-shell SiGe-based nanocrystals combining silicon on insulator dewetting in a molecular beam epitaxy reactor with an ex situ Ge condensation process. With an in situ two-step process (annealing and Ge deposition) we produce two families of islands on the same sample: Si-rich, formed during the first step and, all around them, Ge-rich formed after Ge deposition. By increasing the amount of Ge deposited on the annealed samples from 0 to 18 monolayers, the islands' shape in the Si-rich zones can be tuned from elongated and flat to more symmetric and with a larger vertical aspect ratio. At the same time, the spatial extension of the Ge-rich zones is progressively increased as well as the Ge content in the islands. Further processing by ex situ rapid thermal oxidation results in the formation of a core-shell composition profile in both Si and Ge-rich zones with atomically sharp heterointerfaces. The Ge condensation induces a Ge enrichment of the islands' shell of up to 50% while keeping a pure Si core in the Si-rich zones and a ∼25% SiGe alloy in the Ge-rich ones. The large lattice mismatch between core and shell, the absence of dislocations and the islands' monocrystalline nature render this novel class of nanostructures a promising device platform for strain-based band-gap engineering. Finally, this method can be used for the implementation of ultralarge scale meta-surfaces with dielectric Mie resonators for light manipulation at the nanoscale.
Tasks for development of SiC/SiC composites as structural material in a fusion reactor

International Nuclear Information System (INIS)

Yamada, Reiji

1997-01-01

SiC/SiC composites are chosen for a structural material of blankets in DREAM Reactor that has been proposed as a power reactor by JAERI. The main requirements and the target values in the DREAM conceptual design were described, and compared to available experimental data. (author)
Targeting NF-kB signaling with polymeric hybrid micelles that co-deliver siRNA and dexamethasone for arthritis therapy.

Science.gov (United States)

Wang, Qin; Jiang, Hao; Li, Yan; Chen, Wenfei; Li, Hanmei; Peng, Ke; Zhang, Zhirong; Sun, Xun

2017-04-01

The transcription factor NF-kB plays a pivotal role in the pathogenesis of rheumatoid arthritis. Here we attempt to slow arthritis progression by co-delivering the glucocorticoid dexamethasone (Dex) and small-interfering RNA targeting NF-kB p65 using our previously developed polymeric hybrid micelle system. These micelles contain two similar amphiphilic copolymers: polycaprolactone-polyethylenimine (PCL-PEI) and polycaprolactone-polyethyleneglycol (PCL-PEG). The hybrid micelles loaded with Dex and siRNA effectively inhibited NF-kB signaling in murine macrophages more efficiently than micelles containing either Dex or siRNA on their own. In addition, the co-delivery system was able to switch macrophages from the M1 to M2 state. Injecting hybrid micelles containing Dex and siRNA into mice with collagen-induced arthritis led the therapeutic agents to accumulate in inflamed joints and reduce inflammation, without damaging renal or liver function. Thus, blocking NF-kB activation in inflammatory tissue using micelle-based co-delivery may provide a new approach for treating inflammatory disease. Copyright © 2017 Elsevier Ltd. All rights reserved.
Enhanced delivery of PEAL nanoparticles with ultrasound targeted microbubble destruction mediated siRNA transfection in human MCF-7/S and MCF-7/ADR cells in vitro

Directory of Open Access Journals (Sweden)

Teng Y

2015-08-01

Full Text Available Yanwei Teng,1,2,* Min Bai,3,* Ying Sun,2 Qi Wang,1,2 Fan Li,3 Jinfang Xing,3 Lianfang Du,3 Tao Gong,1 Yourong Duan2 1Key Laboratory of Drug Targeting and Novel Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, People’s Republic of China; 2State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, People’s Republic of China; 3Department of Ultrasound, Shanghai First People’s Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: The gene knockdown activity of small interfering RNA (siRNA has led to their use as potential therapeutics for a variety of diseases. However, successful gene therapy requires safe and efficient delivery systems. In this study, we choose mPEG-PLGA-PLL nanoparticles (PEAL NPs with ultrasound targeted microbubble destruction (UTMD to efficiently deliver siRNA into cells. An emulsification-solvent evaporation method was used to prepare siRNA-loaded PEAL NPs. The NPs possessed an average size of 132.6±10.3 nm (n=5, with a uniform spherical shape, and had an encapsulation efficiency (EE of more than 98%. As demonstrated by MTT assay, neither PEAL NPs nor siRNA-loaded PEAL NPs showed cytotoxicity even at high concentrations. The results of cellular uptake showed, with the assistance of UTMD, the siRNA-loaded PEAL NPs can be effectively internalized and can subsequently release siRNA in cells. Taken together, PEAL NPs with UTMD may be highly promising for siRNA delivery, making it possible to fully exploit the potential of siRNA-based therapeutics. Keywords: gene delivery, mPEG-PLGA-PLL, UTMD, emulsification-solvent evaporation method, orthogonal design
Effect of substrate roughness on growth of diamond by hot filament ...

Indian Academy of Sciences (India)

Administrator

Polycrystalline diamond coatings are grown on Si (100) substrate by hot filament CVD technique. We investigate ... toughness of the film as the crystal changes its phase from monocrystalline to .... is a characteristic of graphite. We mark the.
Reduction of bilirubin by targeting human heme oxygenase-1 through siRNA.

Science.gov (United States)

Xia, Zhen-Wei; Li, Chun-E; Jin, You-Xin; Shi, Yi; Xu, Li-Qing; Zhong, Wen-Wei; Li, Yun-Zhu; Yu, Shan-Chang; Zhang, Zi-Li

2007-04-01

Neonatal hyperbilirubinemia is a common clinical condition caused mainly by the increased production and decreased excretion of bilirubin. Current treatment is aimed at reducing the serum levels of bilirubin. Heme oxygenase-1 (HO-1) is a rate-limiting enzyme that generates bilirubin. In this study we intended to suppress HO-1 using the RNA interference technique. Small interfering RNA (siRNA)-A, -B, and -C were designed based on human HO-1 (hHO-1) mRNA sequences. siRNA was transfected into a human hepatic cell line (HL-7702). hHO-1 transcription and protein levels were then determined. In addition, the inhibitory effect of siRNA on hHO-1 was assessed in cells treated with hemin or transfected with an hHO-1 plasmid. siRNA-C showed the most potent suppressive effect on hHO-1. This inhibition is dose and time dependent. Compared with control, both hemin and hHO-1 plasmids up-regulated hHO-1 expression in HL-7702 cells. However, the up-regulation was significantly attenuated by siRNA-C. Furthermore, the decrease in hHO-1 activity was coincident with the suppression of its transcription. Finally, siRNA-C was shown to reduce hHO-1 enzymatic activity and bilirubin levels. Thus, this study provides a novel therapeutic rationale by blocking bilirubin formation via siRNA for preventing and treating neonatal hyperbilirubinemia and bilirubin encephalopathy at an early clinical stage.
Charged particles multiplicity in interactions of 3.7 A GeV 28Si with light and heavy target nuclei in nuclear emulsions

International Nuclear Information System (INIS)

Singh, B.K.; Tuli, S.K.

1998-01-01

Results from measurement of multiplicity of different charged particles emitted from the interactions of 3.7 A GeV 28 Si with different target groups in nuclear emulsion and correlations among them are presented. The nature of the dependence of multiplicities of charged particles on the impact parameter is examined. Analysis of data in terms of specific multiplicity for different target groups is performed and the results are discussed in the light of superposition model. (author)
Electromagnetic dissociation of relativistic ²⁸Si by nucleon emission

Energy Technology Data Exchange (ETDEWEB)

Sonnadara, Upal Jayasiri [Univ. of Pittsburgh, PA (United States)

1992-12-01

A detailed study of the electromagnetic dissociation of ²⁸Si by nucleon emission at E_lab/A = 14.6 (GeV/nucleon was carried out with ²⁸Si beams interacting on ²⁰⁸Pb). ¹²⁰Sn. ⁶⁴C targets. The measurements apparatus consists of detectors in the target area which measure the energy and charged multiplicity, and a forward spectrometer which measures the position, momentum and energy of the reaction fragments. The exclusive electromagnetic dissociation cross sections for decay channels having multiple nucleons in the final state have been measured which enables the selection of events produced in pure electromagnetic interactions. The measured cross sections agree well with previous measurements obtained for the removal of a few nucleons as well as with measurements on total charge removal cross sections from other experiments. The dependence of the integrated cross sections on the target charge Z_T and the target mass AT confirms that for higher Z targets the excitation is largely electromagnetic. Direct measurements of the excitation energy for the electromagnetic dissociation of ²⁸Si → p+²⁷Al and ²⁸Si → n+²⁷Si have been obtained through a calculation of the invariant mass in kinematically, reconstructed events. The excitation energy spectrum for all targets peak near the isovector giant dipole resonance in ²⁸Si. These distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear ²⁸Si(_γ,p)²⁷Al and ²⁸Si(_γ,n)²⁷Si. The possibilities of observing double giant dipole resonance excitations in ²⁸Si have been investigated with cross section measurements as well as with excitation energy reconstruction.
Development of antibody-modified chitosan nanoparticles for the targeted delivery of siRNA across the blood-brain barrier as a strategy for inhibiting HIV replication in astrocytes.

Science.gov (United States)

Gu, Jijin; Al-Bayati, Karam; Ho, Emmanuel A

2017-08-01

RNA interference (RNAi)-mediated gene silencing offers a novel treatment and prevention strategy for human immunodeficiency virus (HIV) infection. HIV was found to infect and replicate in human brain cells and can cause neuroinfections and neurological deterioration. We designed dual-antibody-modified chitosan/small interfering RNA (siRNA) nanoparticles to deliver siRNA across the blood-brain barrier (BBB) targeting HIV-infected brain astrocytes as a strategy for inhibiting HIV replication. We hypothesized that transferrin antibody and bradykinin B2 antibody could specifically bind to the transferrin receptor (TfR) and bradykinin B2 receptor (B2R), respectively, and deliver siRNA across the BBB into astrocytes as potential targeting ligands. In this study, chitosan nanoparticles (CS-NPs) were prepared by a complex coacervation method in the presence of siRNA, and antibody was chemically conjugated to the nanoparticles. The antibody-modified chitosan nanoparticles (Ab-CS-NPs) were spherical in shape, with an average particle size of 235.7 ± 10.2 nm and a zeta potential of 22.88 ± 1.78 mV. The therapeutic potential of the nanoparticles was evaluated based on their cellular uptake and gene silencing efficiency. Cellular accumulation and gene silencing efficiency of Ab-CS-NPs in astrocytes were significantly improved compared to non-modified CS-NPs and single-antibody-modified CS-NPs. These results suggest that the combination of anti-Tf antibody and anti-B2 antibody significantly increased the knockdown effect of siRNA-loaded nanoparticles. Thus, antibody-mediated dual-targeting nanoparticles are an efficient and promising delivery strategy for inhibiting HIV replication in astrocytes. Graphical abstract Graphic representation of dual-antibody-conjugated chitosan nanoparticles for the targeted delivery of siRNA across the blood-brain barrier (BBB) for inhibiting HIV replication in astrocytes. a Nanoparticle delivery to the BBB and penetration. b Tf

Crystal plasticity study of monocrystalline stochastic honeycombs under in-plane compression

International Nuclear Information System (INIS)

Ma, Duancheng; Eisenlohr, Philip; Epler, Eike; Volkert, Cynthia A.; Shanthraj, Pratheek; Diehl, Martin; Roters, Franz; Raabe, Dierk

2016-01-01

We present a study on the plastic deformation of single crystalline stochastic honeycombs under in-plane compression using a crystal plasticity constitutive description for face-centered cubic (fcc) materials, focusing on the very early stage of plastic deformation, and identifying the interplay between the crystallographic orientation and the cellular structure during plastic deformation. We observe that despite the stochastic structure, surprisingly, the slip system activations in the honeycombs are almost identical to their corresponding bulk single crystals at the early stage of the plastic deformation. On the other hand, however, the yield stresses of the honeycombs are nearly independent of their crystallographic orientations. Similar mechanical response is found in compression testing of nanoporous gold micro-pillars aligned with various crystallographic orientations. The macroscopic stress tensors of the honeycombs show the same anisotropy as their respective bulk single crystals. Locally, however, there is an appreciable fluctuation in the local stresses, which are even larger than for polycrystals. This explains why the Taylor/Schmid factor associated with the crystallographic orientation is less useful to estimate the yield stresses of the honeycombs than the bulk single crystals and polycrystals, and why the plastic deformation occurs at smaller strains in the honeycombs than their corresponding bulk single crystals. Besides these findings, the observations of the crystallographic reorientation suggest that conventional orientation analysis tools, such as inverse pole figure and related tools, would in general fail to study the plastic deformation mechanism of monocrystalline cellular materials.
Microstructure and temperature coefficient of resistance of thin cermet resistor films deposited from CrSi2-Cr-SiC targets by S-gun magnetron

International Nuclear Information System (INIS)

Felmetsger, Valery V.

2010-01-01

Technological solutions for producing nanoscale cermet resistor films with sheet resistances above 1000 Ω/□ and low temperature coefficients of resistance (TCR) have been investigated. 2-40 nm thick cermet films were sputter deposited from CrSi 2 -Cr-SiC targets by a dual cathode dc S-gun magnetron. In addition to studying film resistance versus temperature, the nanofilm structural features and composition were analyzed using scanning electron microscopy, atomic force microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and electron energy loss spectroscopy. This study has revealed that all cermet resistor films deposited at ambient and elevated temperatures were amorphous. The atomic ratio of Si to Cr in these films was about 2 to 1. The film TCR displayed a significant increase when the deposited film thickness was reduced below 2.5 nm. An optimized sputter process consisting of wafer degassing, cermet film deposition at elevated temperature with rf substrate bias, and a double annealing in vacuum, consisting of in situ annealing following the film sputtering and an additional annealing following the exposure of the wafers to air, has been found to be very effective for the film thermal stabilization and for fine tuning the film TCR. Cermet films with thicknesses in the range of 2.5-4 nm deposited using this technique had sheet resistances ranging from 1800 to 1200 Ω/□ and TCR values from -50 ppm/ deg. C to near zero, respectively. A possible mechanism responsible for the high efficiency of annealing the cermet films in vacuum (after preliminary exposure to air), resulting in resistance stabilization and TCR reduction, is also discussed.
Development and applications of monocrystalline silicon radiation sensors fabricated at Comision Nacional de Energia Atomica (CNEA)

International Nuclear Information System (INIS)

Bolzi, C; Bruno, C; Duran, J; Godfrin, E; Martinez Bogado, M; Pla, J; Tamasi, M

2005-01-01

The development of silicon photovoltaic sensors at CNEA has begun in 1998.These sensors, fabricated in the Photovoltaic Laboratory of the Solar Energy Group at Constituyentes Atomic Center, have been used to build low cost radiometers as well as solar angular position sensors on board of artificial satellites.The design, fabrication and calibration of these sensors have been made in different prototypes in order to analyze its performance and to evaluate its limitations.Nowadays, several commercial prototypes have been distributed in different laboratories of our country in order to evaluate them in real work conditions.Particularly, the first experiment of argentine solar cells on space performed on board of SAC-A satellite, included the fabrication of position sensors of this satellite as part of the alignment system of the solar array respect to the sun.In this article, the state of the art of monocrystalline silicon photovoltaic sensors fabricated at CNEA for terrestrial and space applications is presented
Formation of Various Pyramidal Structures on Monocrystalline Silicon Surface and Their Influence on the Solar Cells

Directory of Open Access Journals (Sweden)

Yangang Han

2013-01-01

Full Text Available Texturization is a useful method to enhance the optical absorption of monocrystalline silicon wafers by light-trapping effect in solar cell processing. In present study, a series of textured wafers with various pyramid sizes ranging from 200 nm to 10 μm were fabricated by modified wet-chemical method and characterized. The results show that there is little difference in the reflectance with the pyramid sizes from 1 to 10 μm, which is consistent with the ray-tracing simulation results. However, the light-trapping function of the 200 nm sample below the geometrical optics limit is much weaker. The solar cells fabricated from the 1 μm samples own the highest power conversion efficiency of 18.17% due to a better coverage of metal finger lines than the larger ones, and the 200 nm samples have the lowest efficiency of 10.53%.
Covalent Strategies for Targeting Messenger and Non-Coding RNAs: An Updated Review on siRNA, miRNA and antimiR Conjugates

Directory of Open Access Journals (Sweden)

Santiago Grijalvo

2018-02-01

Full Text Available Oligonucleotide-based therapy has become an alternative to classical approaches in the search of novel therapeutics involving gene-related diseases. Several mechanisms have been described in which demonstrate the pivotal role of oligonucleotide for modulating gene expression. Antisense oligonucleotides (ASOs and more recently siRNAs and miRNAs have made important contributions either in reducing aberrant protein levels by sequence-specific targeting messenger RNAs (mRNAs or restoring the anomalous levels of non-coding RNAs (ncRNAs that are involved in a good number of diseases including cancer. In addition to formulation approaches which have contributed to accelerate the presence of ASOs, siRNAs and miRNAs in clinical trials; the covalent linkage between non-viral vectors and nucleic acids has also added value and opened new perspectives to the development of promising nucleic acid-based therapeutics. This review article is mainly focused on the strategies carried out for covalently modifying siRNA and miRNA molecules. Examples involving cell-penetrating peptides (CPPs, carbohydrates, polymers, lipids and aptamers are discussed for the synthesis of siRNA conjugates whereas in the case of miRNA-based drugs, this review article makes special emphasis in using antagomiRs, locked nucleic acids (LNAs, peptide nucleic acids (PNAs as well as nanoparticles. The biomedical applications of siRNA and miRNA conjugates are also discussed.
Purity of targets prepared on Cu substrates

Science.gov (United States)

Méens, A.; Rossini, I.; Sens, J. C.

1993-09-01

The purity of several elemental self-supporting targets usually prepared by evaporation onto soluble Cu substrates has been studied. The targets were analysed by Rutherford backscattering and instrumental neutron activation analysis. Because of the high percentage of Cu observed in some Si targets, further measurements, including transmission electron microscopy, have been performed on Si targets deposited by e-gun bombardment onto Cu and ion-beam sputtering onto betaine.
Isotopic effects in sub-barrier fusion of Si + Si systems

Science.gov (United States)

Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Bourgin, D.; Čolović, P.; Corradi, L.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Szilner, S.; Urbani, M.; Zhang, G. L.

2018-04-01

Background: Recent measurements of fusion cross sections for the 28Si+28Si system revealed a rather unsystematic behavior; i.e., they drop faster near the barrier than at lower energies. This was tentatively attributed to the large oblate deformation of 28Si because coupled-channels (CC) calculations largely underestimate the 28Si+28Si cross sections at low energies, unless a weak imaginary potential is applied, probably simulating the deformation. 30Si has no permanent deformation and its low-energy excitations are of a vibrational nature. Previous measurements of this system reached only 4 mb, which is not sufficient to obtain information on effects that should show up at lower energies. Purpose: The aim of the present experiment was twofold: (i) to clarify the underlying fusion dynamics by measuring the symmetric case 30Si+30Si in an energy range from around the Coulomb barrier to deep sub-barrier energies, and (ii) to compare the results with the behavior of 28Si+28Si involving two deformed nuclei. Methods: 30Si beams from the XTU tandem accelerator of the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare were used, bombarding thin metallic 30Si targets (50 μ g /cm2) enriched to 99.64 % in mass 30. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ERs) at very forward angles, and angular distributions of ERs were measured. Results: The excitation function of 30Si+30Si was measured down to the level of a few microbarns. It has a regular shape, at variance with the unusual trend of 28Si+28Si . The extracted logarithmic derivative does not reach the LCS limit at low energies, so that no maximum of the S factor shows up. CC calculations were performed including the low-lying 2+ and 3- excitations. Conclusions: Using a Woods-Saxon potential the experimental cross sections at low energies are overpredicted, and this is a clear sign of hindrance, while the calculations performed with a M3Y + repulsion
Targeted partial surface modification with nano-SiO2@Li2CoPO4F as high-voltage cathode material for LIBs

Science.gov (United States)

Chang, Caiyun; Huang, Zhipeng; Tian, Runsai; Jiang, Xinyu; Li, Chunsheng; Feng, Jijun

2017-10-01

Tuning whole/partial surface modification on cathode material with oxide material is a sought-after method to enhance the electrochemical performance in power storage field. Herein, nano-SiO2 targeted partial surface modified high voltage cathode material Li2CoPO4F has been successfully fabricated via a facile self-assembly process in silica dispersion at ambient temperature. With the aid of polar -OH groups attracted on the surface of SiO2 micelles, the nano-SiO2 preferentially nestle up along the borders and boundaries of Li2CoPO4F particles, where protection should be deployed with emphasis against the undesirable interactions between materials and electrolytes. Compared with pristine Li2CoPO4F, the SiO2 selectively modified Li2CoPO4F cathode materials, especially LCPF-3S, exhibit desirable electrochemical performances with higher discharge capacity, more outstanding cycle stability and favorable rate capability without any additional carbon involved. The greatly enhanced electrochemical properties can be attributed to the improved lithium-ion diffusion kinetics and structure tolerance during repeated lithiation/delithiation process. Such findings reveal a great potential of nano-SiO2 modified Li2CoPO4F as high energy cathode material for lithium ion batteries.
Advances in targeted delivery of small interfering RNA using simple bioconjugates

DEFF Research Database (Denmark)

Nielsen, Christoffer; Kjems, Jørgen; Sorensen, Kristine Rothaus

2014-01-01

with a targeting moiety, in a simple bioconjugate construct. We discuss the use of different types of targeting moieties, as well as the different conjugation strategies employed for preparing these bioconjugate constructs that deliver the siRNA to target cells. We focus especially on the in-built or passive......Introduction: Development of drugs based on RNA interference by small interfering RNA (siRNA) has been progressing slowly due to a number of challenges associated with the in vivo behavior of siRNA. A central problem is controlling siRNA delivery to specific cell types. Here, we review existing...... literature on one type of strategy for solving the issue of cell-specific delivery of siRNA, namely delivering the siRNA as part of simple bioconjugate constructs. Areas covered: This review presents current experience from strategies aimed at targeting siRNA to specific cell types, by associating the siRNA...
In vivo efficacy and off-target effects of locked nucleic acid (LNA) and unlocked nucleic acid (UNA) modified siRNA and small internally segmented interfering RNA (sisiRNA) in mice bearing human tumor xenografts

NARCIS (Netherlands)

Mook, O. R. F.; Vreijling, Jeroen; Wengel, Suzy L.; Wengel, Jesper; Zhou, Chuanzheng; Chattopadhyaya, Jyoti; Baas, Frank; Fluiter, Kees

2010-01-01

The clinical use of small interfering RNA (siRNA) is hampered by poor uptake by tissues and instability in circulation. In addition, off-target effects pose a significant additional problem for therapeutic use of siRNA. Chemical modifications of siRNA have been reported to increase stability and
Endothermic decompositions of inorganic monocrystalline thin plates. I. Shape of polycrystalline product domains versus constraints and time

Science.gov (United States)

Bertrand, G.; Comperat, M.; Lallemant, M.; Watelle, G.

1980-03-01

Copper sulfate pentahydrate dehydration into trihydrate was investigated using monocrystalline platelets with varying crystallographic orientations. The morphological and kinetic features of the trihydrate domains were examined. Different shapes were observed: polygons (parallelograms, hexagons) and ellipses; their conditions of occurrence are reported in the (P, T) diagram. At first (for about 2 min), the ratio of the long to the short axes of elliptical domains changes with time; these subsequently develop homothetically and the rate ratio is then only pressure dependent. Temperature influence is inferred from that of pressure. Polygonal shapes are time dependent and result in ellipses. So far, no model can be put forward. Yet, qualitatively, the polygonal shape of a domain may be explained by the prevalence of the crystal arrangement and the elliptical shape by that of the solid tensorial properties. The influence of those factors might be modulated versus pressure, temperature, interface extent, and, thus, time.
Atomistic scale nanoscratching behavior of monocrystalline Cu influenced by water film in CMP process

Science.gov (United States)

Shi, Junqin; Chen, Juan; Fang, Liang; Sun, Kun; Sun, Jiapeng; Han, Jing

2018-03-01

The effect of water film on the nanoscratching behavior of monocrystalline Cu was studied by molecular dynamics (MD) simulation. The results indicate that the friction force acting on abrasive particle increases due to the resistance of water film accumulating ahead of particle, but the water film with lubrication decreases friction force acting on Cu surface. The accumulation of water molecules around particle causes the anisotropy of ridge and the surface damage around the groove, and the water molecules remaining in the groove lead to the non-regular groove structure. The dislocation evolution displays the re-organization of the dislocation network in the nanoscratching process. The evaluation of removal efficiency shows the number of removed Cu atoms decreases with water film thickness. It is considered that an appropriate rather than a high removal efficiency should be adopted to evaluate the polishing process in real (chemical mechanical polishing) CMP. These results are helpful to reveal the polishing mechanism under the effect of water film from physical perspective, which benefits the development of ultra-precision manufacture and miniaturized components, as well as the innovation of CMP technology.
Oxidation behavior of arc evaporated Al-Cr-Si-N thin films

Energy Technology Data Exchange (ETDEWEB)

Tritremmel, Christian; Daniel, Rostislav; Mitterer, Christian; Mayrhofer, Paul H.; Lechthaler, Markus; Polcik, Peter [Christian Doppler Laboratory for Advanced Hard Coatings, Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Christian Doppler Laboratory for Application Oriented Coating Development, Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); OC Oerlikon Balzers AG, Iramali 18, LI-9496 Balzers (Liechtenstein); PLANSEE Composite Materials GmbH, Siebenbuergerstrasse 23, D-86983 Lechbruck am See (Germany)

2012-11-15

The impact of Al and Si on the oxidation behavior of Al-Cr-(Si)-N thin films synthesized by arc evaporation of powder metallurgically prepared Al{sub x}Cr{sub 1-x} targets with x = Al/(Al + Cr) of 0.5, 0.6, and 0.7 and (Al{sub 0.5}Cr{sub 0.5}){sub 1-z}Si{sub z} targets with Si contents of z = 0.05, 0.1, and 0.2 in N{sub 2} atmosphere was studied in detail by means of differential scanning calorimetry, thermogravimetric analysis (TGA), x-ray diffraction, and Raman spectroscopy. Dynamical measurements in synthetic air (up to 1440 Degree-Sign C) revealed the highest onset temperature of pronounced oxidation for nitride coatings prepared from the Al{sub 0.4}Cr{sub 0.4}Si{sub 0.2} target. Isothermal TGA at 1100, 1200, 1250, and 1300 Degree-Sign C highlight the pronounced improvement of the oxidation resistance of Al{sub x}Cr{sub 1-x}N coatings by the addition of Si. The results show that Si promotes the formation of a dense coating morphology as well as a dense oxide scale when exposed to air.
Co-sputtered ZnO:Si thin films as transparent conductive oxides

Energy Technology Data Exchange (ETDEWEB)

Faure, C. [CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F33600 Pessac (France); Clatot, J. [LRCS, 33 Rue St Leu, F-80039 Amiens (France); Teule-Gay, L.; Campet, G. [CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F33600 Pessac (France); Labrugere, C. [CeCaMA, Universite de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, Pessac, F-33608 (France); Nistor, M. [National Institute for Lasers, Plasmas and Radiation Physics, L22, PO Box MG-36, 77125 Bucharest-Magurele (Romania); Rougier, A., E-mail: rougier@icmcb-bordeaux.cnrs.fr [CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F33600 Pessac (France)

2012-12-01

Silicon doped Zinc Oxide thin films, so-called SZO, were deposited at room temperature on glass and plastic substrates by co-sputtering of ZnO and SiO{sub 2} targets. The influence of the SiO{sub 2} target power supply (from 30 to 75 W) on the SZO thin film composition and crystallinity is discussed. Si/Zn atomic ratio, determined by X-ray microprobe, increases from 1.2 to 8.2 at.%. For Si/Zn ratio equal and lower than 3.9%, SZO (S{sub 3.9}ZO) thin films exhibit the Wurzite structure with the (0 0 2) preferred orientation. Larger Si content leads to a decrease in crystallinity. With Si addition, the resistivity decreases down to 3.5 Multiplication-Sign 10{sup -3} Ohm-Sign {center_dot}cm for SZO thin film containing 3.9 at.% of Si prior to an increase. The mean transmittance of S{sub 3.9}ZO thin film on glass substrate approaches 80% (it is about 90% for the film itself) in the visible range (from 400 to 750 nm). Co-sputtered SZO thin films are suitable candidates for large area transparent conductive oxides. - Highlights: Black-Right-Pointing-Pointer Si doped ZnO thin films by co-sputtering of ZnO and SiO{sub 2} targets. Black-Right-Pointing-Pointer Minimum of resistivity for Si doped ZnO thin films containing 3.9% of Si. Black-Right-Pointing-Pointer Si and O environments by X-ray Photoelectron Spectroscopy.
MysiRNA-designer: a workflow for efficient siRNA design.

Directory of Open Access Journals (Sweden)

Mohamed Mysara

Full Text Available The design of small interfering RNA (siRNA is a multi factorial problem that has gained the attention of many researchers in the area of therapeutic and functional genomics. MysiRNA score was previously introduced that improves the correlation of siRNA activity prediction considering state of the art algorithms. In this paper, a new program, MysiRNA-Designer, is described which integrates several factors in an automated work-flow considering mRNA transcripts variations, siRNA and mRNA target accessibility, and both near-perfect and partial off-target matches. It also features the MysiRNA score, a highly ranked correlated siRNA efficacy prediction score for ranking the designed siRNAs, in addition to top scoring models Biopredsi, DISR, Thermocomposition21 and i-Score, and integrates them in a unique siRNA score-filtration technique. This multi-score filtration layer filters siRNA that passes the 90% thresholds calculated from experimental dataset features. MysiRNA-Designer takes an accession, finds conserved regions among its transcript space, finds accessible regions within the mRNA, designs all possible siRNAs for these regions, filters them based on multi-scores thresholds, and then performs SNP and off-target filtration. These strict selection criteria were tested against human genes in which at least one active siRNA was designed from 95.7% of total genes. In addition, when tested against an experimental dataset, MysiRNA-Designer was found capable of rejecting 98% of the false positive siRNAs, showing superiority over three state of the art siRNA design programs. MysiRNA is a freely accessible (Microsoft Windows based desktop application that can be used to design siRNA with a high accuracy and specificity. We believe that MysiRNA-Designer has the potential to play an important role in this area.
Self-organization of nanocluster δ-layers at ion-beam-mixed Si-SiO2 interfaces

International Nuclear Information System (INIS)

Roentzsch, L.

2003-11-01

This diploma thesis presents experimental evidence of a theoretical concept which predicts the self-organization of δ-layers of silicon nanoclusters in the buried oxide of a MOS-like structure. This approach of ''bottom-up'' structuring might be of eminent importance in view of future semiconductor memory devices. Unconventionally, a 15 nm thin SiO 2 layer, which is enclosed by a 50 nm poly-Si capping layer and the Si substrate, is irradiated with Si + ions. Ion impact drives the system to a state far from thermodynamic equilibrium, i.e. the local composition of the target is modified to a degree unattainable in common processes. A region of SiO x (x 2 matrix at a distance of ∼3 nm from the Si substrate. The physical mechanisms of ion mixing of the two Si-SiO 2 interfaces and subsequent phase separation, which result in the desired sample structure, are elucidated from the viewpoint of computer simulations. In addition, experimental evidence is presented based on various methods, including TEM, RBS, and SIMS. A novel method of Si nanocluster decoration is of particular importance which applies Ge as contrast enhancing element in TEM studies of tiny Si nanoclusters. (orig.)
Folic acid-conjugated GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2} Nanoprobe for folate receptor-targeted optical and magnetic resonance bi-modal imaging

Energy Technology Data Exchange (ETDEWEB)

Xu, Xianzhu [Jiangxi Normal University, College of Life Science, Jiangxi Provincial Key Laboratory of Protection and Utilization of Subtropical Plant Resources of Jiangxi Province (China); Zhang, Xiaoying; Wu, Yanli, E-mail: Wanny118@126.com [Jiangxi Science and Technology Normal University, Jiangxi Key Laboratory of Organic Chemistry (China)

2016-11-15

Both fluorescent and magnetic nanoprobes have great potential applications for diagnostics and therapy. In the present work, a folic acid-conjugated and silica-modified GdPO{sub 4}:Tb{sup 3+} (GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA) dual nanoprobe was strategically designed and synthesized for the targeted dual-modality optical and magnetic resonance (MR) imaging via a facile aqueous method. Their structural, optical, and magnetic properties were determined using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet-visible spectra (UV-Vis), photoluminescence (PL), and superconducting quantum interference device (SQUID). These results indicated that GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA were uniform monodisperse core-shell structured nanorods (NRs) with an average length of ~200 nm and an average width of ~25 nm. The paramagnetic property of the synthesized GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA NRs was confirmed with its linear hysteresis plot (M-H). In addition, the NRs displayed an obvious T{sub 1}-weighted effect and thus it could potentially serve as a T{sub 1}-positive contrast agent. The NRs emitted green lights due to the {sup 5}D{sub 4} → {sup 7}F{sub 5} transition of the Tb{sup 3+}. The in vitro assays with NCI-H460 lung cancer cells and human embryonic kidney cell line 293T cells indicated that the GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA nanoprobe could specifically bind the cells bearing folate receptors (FR). The MTT assay of the NRs revealed that its cytotoxicity was very low. Further in vivo MRI experiments distinctively depict enhanced anatomical features in a xenograft tumor. These results suggest that the GdPO{sub 4}:Tb{sup 3+}@SiO{sub 2}-FA NPs have excellent imaging and cell-targeting abilities for the folate receptor-targeted dual-modality optical and MR imaging and can be potentially used as the nanoprobe for bioimaging.
A novel program to design siRNAs simultaneously effective to highly variable virus genomes.

Science.gov (United States)

Lee, Hui Sun; Ahn, Jeonghyun; Jun, Eun Jung; Yang, Sanghwa; Joo, Chul Hyun; Kim, Yoo Kyum; Lee, Heuiran

2009-07-10

A major concern of antiviral therapy using small interfering RNAs (siRNAs) targeting RNA viral genome is high sequence diversity and mutation rate due to genetic instability. To overcome this problem, it is indispensable to design siRNAs targeting highly conserved regions. We thus designed CAPSID (Convenient Application Program for siRNA Design), a novel bioinformatics program to identify siRNAs targeting highly conserved regions within RNA viral genomes. From a set of input RNAs of diverse sequences, CAPSID rapidly searches conserved patterns and suggests highly potent siRNA candidates in a hierarchical manner. To validate the usefulness of this novel program, we investigated the antiviral potency of universal siRNA for various Human enterovirus B (HEB) serotypes. Assessment of antiviral efficacy using Hela cells, clearly demonstrates that HEB-specific siRNAs exhibit protective effects against all HEBs examined. These findings strongly indicate that CAPSID can be applied to select universal antiviral siRNAs against highly divergent viral genomes.
SiC formation for a solar cell passivation layer using an RF magnetron co-sputtering system

Science.gov (United States)

2012-01-01

In this paper, we describe a method of amorphous silicon carbide film formation for a solar cell passivation layer. The film was deposited on p-type silicon (100) and glass substrates by an RF magnetron co-sputtering system using a Si target and a C target at a room-temperature condition. Several different SiC [Si1-xCx] film compositions were achieved by controlling the Si target power with a fixed C target power at 150 W. Then, structural, optical, and electrical properties of the Si1-xCx films were studied. The structural properties were investigated by transmission electron microscopy and secondary ion mass spectrometry. The optical properties were achieved by UV-visible spectroscopy and ellipsometry. The performance of Si1-xCx passivation was explored by carrier lifetime measurement. PMID:22221730
siRNA and innate immunity.

Science.gov (United States)

Robbins, Marjorie; Judge, Adam; MacLachlan, Ian

2009-06-01

Canonical small interfering RNA (siRNA) duplexes are potent activators of the mammalian innate immune system. The induction of innate immunity by siRNA is dependent on siRNA structure and sequence, method of delivery, and cell type. Synthetic siRNA in delivery vehicles that facilitate cellular uptake can induce high levels of inflammatory cytokines and interferons after systemic administration in mammals and in primary human blood cell cultures. This activation is predominantly mediated by immune cells, normally via a Toll-like receptor (TLR) pathway. The siRNA sequence dependency of these pathways varies with the type and location of the TLR involved. Alternatively nonimmune cell activation may also occur, typically resulting from siRNA interaction with cytoplasmic RNA sensors such as RIG1. As immune activation by siRNA-based drugs represents an undesirable side effect due to the considerable toxicities associated with excessive cytokine release in humans, understanding and abrogating this activity will be a critical component in the development of safe and effective therapeutics. This review describes the intracellular mechanisms of innate immune activation by siRNA, the design of appropriate sequences and chemical modification approaches, and suitable experimental methods for studying their effects, with a view toward reducing siRNA-mediated off-target effects.

On the efficiency calibration of Si(Li) detector in the low-energy region using thick-target bremsstrahlung

Energy Technology Data Exchange (ETDEWEB)

An, Z. E-mail: anzhu@scu.edu.cn; Liu, M.T

2002-10-01

In this paper, the efficiency calibration of a Si(Li) detector in the low-energy region down to 0.58 keV has been performed using thick-carbon-target bremsstrahlung by 19 keV electron impact. The shape of the efficiency calibration curve was determined from the thick-carbon-target bremsstrahlung spectrum, and the absolute value for the efficiency calibration was obtained from the use of {sup 241}Am radioactive standard source. The modified Wentzel's formula for thick-target bremsstrahlung was employed and it was also compared with the most recently developed theoretical model based upon the doubly differential cross-sections for bremsstrahlung of Kissel, Quarles and Pratt. In the present calculation of theoretical bremsstrahlung, the self-absorption correction and the convolution of detector's response function with the bremsstrahlung spectrum have simultaneously been taken into account. The accuracy for the efficiency calibration in the low-energy region with the method described here was estimated to be about 6%. Moreover, the self-absorption correction calculation based upon the prescription of Wolters et al. has also been presented as an analytical factor with the accuracy of {approx}1%.
Preclinical and clinical development of siRNA-based therapeutics.

Science.gov (United States)

Ozcan, Gulnihal; Ozpolat, Bulent; Coleman, Robert L; Sood, Anil K; Lopez-Berestein, Gabriel

2015-06-29

The discovery of RNA interference, first in plants and Caenorhabditis elegans and later in mammalian cells, led to the emergence of a transformative view in biomedical research. Knowledge of the multiple actions of non-coding RNAs has truly allowed viewing DNA, RNA and proteins in novel ways. Small interfering RNAs (siRNAs) can be used as tools to study single gene function both in vitro and in vivo and are an attractive new class of therapeutics, especially against undruggable targets for the treatment of cancer and other diseases. Despite the potential of siRNAs in cancer therapy, many challenges remain, including rapid degradation, poor cellular uptake and off-target effects. Rational design strategies, selection algorithms, chemical modifications and nanocarriers offer significant opportunities to overcome these challenges. Here, we review the development of siRNAs as therapeutic agents from early design to clinical trial, with special emphasis on the development of EphA2-targeting siRNAs for ovarian cancer treatment. Copyright © 2015 Elsevier B.V. All rights reserved.
Elastic and inelastic scattering of α particles at 41MeV and elastic scattering of 3He at 46MeV on 27Al, 28Si, 29Si, and 30Si

International Nuclear Information System (INIS)

Mariolopoulos, Georges.

1976-01-01

Elastic and inelastic scattering of α particles at 41MeV has been studied on 27 Al, 28 Si, 29 Si and 30 Si between 30 and 160deg c.m. The elastic cross section for α particles on 28 Si shows more oscillation than that for the other targets in the region between 80 and 160deg c.m. The data have been analyzed using both a 9 parameters optical model potential and a coupled channel code. In order to investigate the assumption that the abnormal cross section of 28 Si is due to a cluster effect, the 27 Al, 28 Si, 29 Si, 30 Si( 3 He, 3 He) reaction have been studied between 30 and 110deg c.m., using a 46MeV beam. In this case the angular distributions of the three Si isotopes are similar. An optical model analysis of the data reveals no anomaly [fr
Conjugate of biotin with silicon(IV) phthalocyanine for tumor-targeting photodynamic therapy.

Science.gov (United States)

Li, Ke; Qiu, Ling; Liu, Qingzhu; Lv, Gaochao; Zhao, Xueyu; Wang, Shanshan; Lin, Jianguo

2017-09-01

In order to improve the efficacy of photodynamic therapy (PDT), biotin was axially conjugated with silicon(IV) phthalocyanine (SiPc) skeleton to develop a new tumor-targeting photosensitizer SiPc-biotin. The target compound SiPc-biotin showed much higher binding affinity toward BR-positive (biotin receptor overexpressed) HeLa human cervical carcinoma cells than its precursor SiPc-pip. However, when the biotin receptors of HeLa cells were blocked by free biotin, >50% uptake of SiPc-biotin was suppressed, demonstrating that SiPc-biotin could selectively accumulate in BR-positive cancer cells via the BR-mediated internalization. The confocal fluorescence images further confirmed the target binding ability of SiPc-biotin. As a consequence of specificity of SiPc-biotin toward BR-positive HeLa cells, the photodynamic effect was also largely dependent on the BR expression level of HeLa cells. The photodynamic activities of SiPc-biotin against HeLa cells were dramatically reduced when the biotin receptors were blocked by the free biotin (IC 50 : 0.18μM vs. 0.46μM). It is concluded that SiPc-biotin can selectively damage BR-positive cancer cells under irradiation. Furthermore, the dark toxicity of SiPc-biotin toward human normal liver cell lines LO2 was much lower than that of its precursor SiPc-pip. The targeting photodynamic activity and low dark toxicity suggest that SiPc-biotin is a promising photosensitizer for tumor-targeting photodynamic therapy. Copyright © 2017 Elsevier B.V. All rights reserved.
The Research Progress of SiRNA Targeting Notch1 on Tumor Cells: A Mini Review of the State of the Art

Directory of Open Access Journals (Sweden)

Lanfen Huo

2016-09-01

Full Text Available Notch signaling is a highly conserved signaling pathway, playing an important role in a variety of cell differentiation, development and regulation. Notch signaling includes Notch1-4; Notch1 gene encodes Notch1 signaling that can shorten cell cycle, enhance cell proliferation, inhibit cell differentiation, and promote apoptosis. Mutation and overexpression of the Notch1 gene may induce tumorigenesis, which plays an important role in the development of tumors across a variety of signaling pathways. Currently, using RNA interference technology (RNAi synthesizing small interference RNA (siRNA targeting Notch1 gene（siNotch1）has become a hot topic, and clinical application of gene silencing has also obtained a certain therapeutic effect. In this paper, the application of Notch1 gene silencing in tumor progress was reviewed.
Efficiency of the monocrystalline photovoltaic modules in conversion solar radiation into electrical energy; Eficiencia de modulos fotovoltaicos monocristalinos na conversao de radiacao solar em energia eletrica

Energy Technology Data Exchange (ETDEWEB)

Silva, Carliane Diniz e [Universidade Estadual do Maranhao (UEMA), Sao Luis, MA (Brazil). Dept. de Engenharia Agricola], Email: carlianeds@yahoo.com.br; Seraphim, Odivaldo Jose [Universidade Estadual Paulista (FCA/UNESP), SP (Brazil). Fac. de Ciencias Agronomicas. Dept. de Engenharia Rural], Email: seraphim@fca.unesp.br

2006-07-01

With the scarcity of the conventional sources of energy production, other options must be considered, as the use of energy resources you renewed, that they offer to multiple advantages. One of the options to the supply of energy of the agricultural users is the photovoltaic solar systems for the local promotion of the quality of life. The objective of this study was to evaluate two marks of monocrystalline photovoltaic modules in different angles of inclination. The modules had presented low efficiency of conversion in conditions of field for incident solar radiation. (author)
Plasma processing of the Si(0 0 1) surface for tuning SPR of Au/Si-based plasmonic nanostructures

Energy Technology Data Exchange (ETDEWEB)

Giangregorio, Maria M. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)]. E-mail: michelaria.giangregorio@ba.imip.cnr.it; Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy); Sacchetti, Alberto [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy); Capezzuto, Pio [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy); Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)

2006-12-15

Au nanoclusters have been deposited on Si(0 0 1) surfaces by sputtering of a metallic Au target using an Ar plasma. Different wet and dry treatments of the Si(0 0 1) surface, including dipping in HF solution and exposure to H{sub 2} and N{sub 2} plasmas, have been applied and the effects of these treatments on the Au nanoparticles/Si interface, the Au nanoclusters aspect ratio and the surface plasmon resonance (SPR) energy and amplitude are investigated exploiting spectroscopic ellipsometry and atomic force microscopy. It is found that the Au nanoclusters aspect ratio depends on the extent of the Au-Si intermixing. The thicker the Au-Si interface layer, the larger the Au nanoparticles aspect ratio and the red-shift of the SPR peak. Furthermore, SiO{sub 2} and the H{sub 2} plasma treatment inhibit the Si-Au intermixing, while HF-dipping and the N{sub 2} plasma treatment favour Au-Si intermixing, yielding silicide formation which increases the Si wetting by Au.
Process Characterization of Electrical Discharge Machining of Highly Doped Silicon

Science.gov (United States)

2012-06-01

of mechanism is shown in Figure 2 showing the wire feed panel where the spool of 5 (DiBitonto, et...Uno High efficiency boring of monocrystalline silicon ingot by EDM RAM Si (P-type) conductivity 0.01 ohm-cm 1mm Cu pipe electrode, rotating at
AOARD Overview Power and Energy Emphasis

Science.gov (United States)

2010-09-01

large-area Si solar panels from 15 to 16.8% - Develop nanophosphor coating to down-convert solar UV to visible in an affordable manner He Plasma Jet at...radiation - Doesn’t degrade operating life of solar cells Silicon Solar Cell Material Laboratory efficiency % Production efficiency % Monocrystalline
H0 candidates from the decays Σ-p and Λpπ-, produced in heavy ion collisions Si beam on Pb target

International Nuclear Information System (INIS)

Longacre, R.S.

1997-01-01

There is considerable interest in searching for strange quark matter (strangelets). The lowest strangelet state is thought to be a six quark dibaryon singlet spin zero state called the H 0 predicted by R.L. Jaffe. The authors present H 0 candidate events, where H 0 (2210) is observed through the weak decay modes Σ - p and Λpπ - , produced in central heavy ion collisions with 14.6 x A Gev/c Si beam on Pb target. The lifetime is consistent with ∼4 cm cr in both channels approximately 1/3 of an H 0 (2210) which decays into Σ - p is produced per central Si Pb collision. The branching ratio between Λpπ - and Σ - p is around 11% ± 3%
Single-phase {beta}-FeSi{sub 2} thin films prepared on Si wafer by femtosecond laser ablation and its photoluminescence at room temperature

Energy Technology Data Exchange (ETDEWEB)

Lu Peixiang [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)]. E-mail: lupeixiang@mail.hust.edu.cn; Zhou Youhua [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China) and Physics and Information School, Jianghan University, Wuhan 430056 (China)]. E-mail: yhzhou@jhun.edu.cn; Zheng Qiguang [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Yang Guang [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2006-02-06

Single-phase {beta}-FeSi{sub 2} thin films were prepared on Si(100) and Si(111) wafers by using femtosecond laser deposition with a FeSi{sub 2} alloy target for the first time. X-ray diffraction (XRD), field scanning electron microscopy (FSEM), scanning probe microscopy (SPM), electron backscattered diffraction pattern (EBSD), and Fourier-transform Raman infrared spectroscopy (FTRIS) were used to characterize the structure, composition, and properties of the {beta}-FeSi{sub 2}/Si films. The orientation of {beta}-FeSi{sub 2} grains was found to depend on the orientation of the Si substrates, and photoluminescence at wavelength of 1.53 {mu}m was observed from the single-phase {beta}-FeSi{sub 2}/Si thin film at room temperature (20 {sup o}C)
Mechanical properties, chemical analysis and evaluation of antimicrobial response of Si-DLC coatings fabricated on AISI 316 LVM substrate by a multi-target DC-RF magnetron sputtering method for potential biomedical applications

Science.gov (United States)

Bociaga, Dorota; Sobczyk-Guzenda, Anna; Szymanski, Witold; Jedrzejczak, Anna; Jastrzebska, Aleksandra; Olejnik, Anna; Jastrzebski, Krzysztof

2017-09-01

In this study silicon doped diamond-like carbon (Si-DLC) coatings were synthesized on two substrates: silicon and AISI 316LVM stainless steel using a multi-target DC-RF magnetron sputtering method. The Si content in the films ranged between 4 and 16 at.%, and was controlled by the electrical power applied in RF regime to Si cathode target. The character of the chemical bonds was revealed by FTIR analysis. With the addition of silicon the hydroxyl absorption (band in the range of 3200-3600 cm-1) increased what suggests more hydrophilic character of the coating. There were also observed significant changes in bonding of Si atoms. For low content of dopant, Si-O-Si bond system is predominant, while for the highest content of silicon there is an evidence of the shift to Si-C bonds in close proximity to methyl groups. The Raman spectroscopy revealed that the G peak position is shifted to a lower wavenumber and the ID/IG ratio decreased with increasing Si content, which indicates an increase in the C-sp3 content. Regardless of the coatings' composition, the improvement of hardness in comparison to pure substrate material (AISI 316 LVM) was observed. Although the reduction of the level of hardness from the level of 10.8 GPa for pure DLC to about 9.4 GPa for the silicon doped coatings was observed, the concomitant improvement of films adhesion with higher amount of Si was revealed. Although incorporation of the dopant to DLC coatings increases the number of E. coli cells which adhered to the examined surfaces, the microbial colonisation remains on the level of substrate material. The presented results prove the potential of Si-DLC coatings in biomedical applications from the point of view of their mechanical properties.
Confirming the RNAi-mediated mechanism of action of siRNA-based cancer therapeutics in mice.

Science.gov (United States)

Judge, Adam D; Robbins, Marjorie; Tavakoli, Iran; Levi, Jasna; Hu, Lina; Fronda, Anna; Ambegia, Ellen; McClintock, Kevin; MacLachlan, Ian

2009-03-01

siRNAs that specifically silence the expression of cancer-related genes offer a therapeutic approach in oncology. However, it remains critical to determine the true mechanism of their therapeutic effects. Here, we describe the preclinical development of chemically modified siRNA targeting the essential cell-cycle proteins polo-like kinase 1 (PLK1) and kinesin spindle protein (KSP) in mice. siRNA formulated in stable nucleic acid lipid particles (SNALP) displayed potent antitumor efficacy in both hepatic and subcutaneous tumor models. This was correlated with target gene silencing following a single intravenous administration that was sufficient to cause extensive mitotic disruption and tumor cell apoptosis. Our siRNA formulations induced no measurable immune response, minimizing the potential for nonspecific effects. Additionally, RNAi-specific mRNA cleavage products were found in tumor cells, and their presence correlated with the duration of target mRNA silencing. Histological biomarkers confirmed that RNAi-mediated gene silencing effectively inhibited the target's biological activity. This report supports an RNAi-mediated mechanism of action for siRNA antitumor effects, suggesting a new methodology for targeting other key genes in cancer development with siRNA-based therapeutics.
SiPM properties at cryogenic temperatures

Energy Technology Data Exchange (ETDEWEB)

Biroth, Maik; Achenbach, Patrick; Thomas, Andreas [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet, Mainz (Germany); Downie, Evangeline [George Washington University, DC (United States); Collaboration: A2-Collaboration

2015-07-01

At the electron accelerator Mainzer Mikrotron (MAMI) an active target build of polarizable scintillators will be operated at approximately 25 mK. To read out the scintillation light, the photodetectors have to withstand cryogenic temperatures of 4 K and high count rates. Therefore the properties of different types of silicon photomultipliers (SiPMs) were studied at cryogenic temperatures. In liquid nitrogen at 77 K, problems with quenching in Hamamatsu SiPMs and with the protective epoxy layer covering Zecotek SiPMs were observed. Tests with one Zecotek SiPM were successful after removal of the epoxy layer in liquid helium at 4 K and no after-pulses could be observed. Fundamental parameters like break-down voltage, single-pixel gain, crosstalk probability and the dark-count rate were measured and compared to room temperature. The photon detection efficiency was estimated by SiPMs response to short LED pulses. All these parameters were extracted by curve-fitting of SiPM charge spectra with a new analytical function.
A modular platform for targeted RNAi therapeutics.

Science.gov (United States)

Kedmi, Ranit; Veiga, Nuphar; Ramishetti, Srinivas; Goldsmith, Meir; Rosenblum, Daniel; Dammes, Niels; Hazan-Halevy, Inbal; Nahary, Limor; Leviatan-Ben-Arye, Shani; Harlev, Michael; Behlke, Mark; Benhar, Itai; Lieberman, Judy; Peer, Dan

2018-03-01

Previous studies have identified relevant genes and signalling pathways that are hampered in human disorders as potential candidates for therapeutics. Developing nucleic acid-based tools to manipulate gene expression, such as short interfering RNAs 1-3 (siRNAs), opens up opportunities for personalized medicine. Yet, although major progress has been made in developing siRNA targeted delivery carriers, mainly by utilizing monoclonal antibodies (mAbs) for targeting 4-8 , their clinical translation has not occurred. This is in part because of the massive development and production requirements and the high batch-to-batch variability of current technologies, which rely on chemical conjugation. Here we present a self-assembled modular platform that enables the construction of a theoretically unlimited repertoire of siRNA targeted carriers. The self-assembly of the platform is based on a membrane-anchored lipoprotein that is incorporated into siRNA-loaded lipid nanoparticles that interact with the antibody crystallizable fragment (Fc) domain. We show that a simple switch of eight different mAbs redirects the specific uptake of siRNAs by diverse leukocyte subsets in vivo. The therapeutic potential of the platform is demonstrated in an inflammatory bowel disease model by targeting colon macrophages to reduce inflammatory symptoms, and in a Mantle Cell Lymphoma xenograft model by targeting cancer cells to induce cell death and improve survival. This modular delivery platform represents a milestone in the development of precision medicine.
A modular platform for targeted RNAi therapeutics

Science.gov (United States)

Kedmi, Ranit; Veiga, Nuphar; Ramishetti, Srinivas; Goldsmith, Meir; Rosenblum, Daniel; Dammes, Niels; Hazan-Halevy, Inbal; Nahary, Limor; Leviatan-Ben-Arye, Shani; Harlev, Michael; Behlke, Mark; Benhar, Itai; Lieberman, Judy; Peer, Dan

2018-01-01

Previous studies have identified relevant genes and signalling pathways that are hampered in human disorders as potential candidates for therapeutics. Developing nucleic acid-based tools to manipulate gene expression, such as short interfering RNAs1-3 (siRNAs), opens up opportunities for personalized medicine. Yet, although major progress has been made in developing siRNA targeted delivery carriers, mainly by utilizing monoclonal antibodies (mAbs) for targeting4-8, their clinical translation has not occurred. This is in part because of the massive development and production requirements and the high batch-to-batch variability of current technologies, which rely on chemical conjugation. Here we present a self-assembled modular platform that enables the construction of a theoretically unlimited repertoire of siRNA targeted carriers. The self-assembly of the platform is based on a membrane-anchored lipoprotein that is incorporated into siRNA-loaded lipid nanoparticles that interact with the antibody crystallizable fragment (Fc) domain. We show that a simple switch of eight different mAbs redirects the specific uptake of siRNAs by diverse leukocyte subsets in vivo. The therapeutic potential of the platform is demonstrated in an inflammatory bowel disease model by targeting colon macrophages to reduce inflammatory symptoms, and in a Mantle Cell Lymphoma xenograft model by targeting cancer cells to induce cell death and improve survival. This modular delivery platform represents a milestone in the development of precision medicine.
Intranasal delivery of antiviral siRNA.

Science.gov (United States)

Barik, Sailen

2011-01-01

Intranasal administration of synthetic siRNA is an effective modality of RNAi delivery for the prevention and therapy of respiratory diseases, including pulmonary infections. Vehicles used for nasal siRNA delivery include established as well as novel reagents, many of which have been recently optimized. In general, they all promote significant uptake of siRNA into the lower respiratory tract, including the lung. When properly designed and optimized, these siRNAs offer significant protection against respiratory viruses such as influenza virus, parainfluenza virus and respiratory syncytial virus (RSV). Nasally administered siRNA remains within the lung and does not access systemic blood flow, as judged by its absence in other major organs such as liver, heart, kidney, and skeletal muscle. Adverse immune reaction is generally not encountered, especially when immunogenic and/or off-target siRNA sequences and toxic vehicles are avoided. In fact, siRNA against RSV has entered Phase II clinical trials in human with promising results. Here, we provide a standardized procedure for using the nose as a specific route for siRNA delivery into the lung of laboratory animals. It should be clear that this simple and efficient system has enormous potential for therapeutics.
Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

International Nuclear Information System (INIS)

Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

2009-01-01

Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.
Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

Science.gov (United States)

Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

2009-05-01

Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.
siMacro: A Fast and Easy Data Processing Tool for Cell-Based Genomewide siRNA Screens

Directory of Open Access Journals (Sweden)

Nitin Kumar Singh

2013-03-01

Full Text Available Growing numbers of studies employ cell line-based systematic short interfering RNA (siRNA screens to study gene functions and to identify drug targets. As multiple sources of variations that are unique to siRNA screens exist, there is a growing demand for a computational tool that generates normalized values and standardized scores. However, only a few tools have been available so far with limited usability. Here, we present siMacro, a fast and easy-to-use Microsoft Office Excel-based tool with a graphic user interface, designed to process single-condition or two-condition synthetic screen datasets. siMacro normalizes position and batch effects, censors outlier samples, and calculates Z-scores and robust Z-scores, with a spreadsheet output of >120,000 samples in under 1 minute.

Nonviral pulmonary delivery of siRNA.

Science.gov (United States)

Merkel, Olivia M; Kissel, Thomas

2012-07-17

RNA interference (RNAi) is an important part of the cell's defenses against viruses and other foreign genes. Moreover, the biotechnological exploitation of RNAi offers therapeutic potential for a range of diseases for which drugs are currently unavailable. Unfortunately, the small interfering RNAs (siRNAs) that are central to RNAi in the cytoplasm are readily degradable by ubiquitous nucleases, are inefficiently targeted to desired organs and cell types, and are excreted quickly upon systemic injection. As a result, local administration techniques have been favored over the past few years, resulting in great success in the treatment of viral infections and other respiratory disorders. Because there are several advantages of pulmonary delivery over systemic administration, two of the four siRNA drugs currently in phase II clinical trials are delivered intranasally or by inhalation. The air-blood barrier, however, has only limited permeability toward large, hydrophilic biopharmaceuticals such as nucleic acids; in addition, the lung imposes intrinsic hurdles to efficient siRNA delivery. Thus, appropriate formulations and delivery devices are very much needed. Although many different formulations have been optimized for in vitro siRNA delivery to lung cells, only a few have been reported successful in vivo. In this Account, we discuss both obstacles to pulmonary siRNA delivery and the success stories that have been achieved thus far. The optimal pulmonary delivery vehicle should be neither cytotoxic nor immunogenic, should protect the payload from degradation by nucleases during the delivery process, and should mediate the intracellular uptake of siRNA. Further requirements include the improvement of the pharmacokinetics and lung distribution profiles of siRNA, the extension of lung retention times (through reduced recognition by macrophages), and the incorporation of reversible or stimuli-responsive binding of siRNA to allow for efficient release of the siRNAs at the
Nanocapsule-mediated cytosolic siRNA delivery for anti-inflammatory treatment.

Science.gov (United States)

Jiang, Ying; Hardie, Joseph; Liu, Yuanchang; Ray, Moumita; Luo, Xiang; Das, Riddha; Landis, Ryan F; Farkas, Michelle E; Rotello, Vincent M

2018-06-05

The use of nanoparticle-stabilized nanocapsules for cytosolic siRNA delivery for immunomodulation in vitro and in vivo is reported. These NPSCs deliver siRNA directly to the cytosol of macrophages in vitro with concomitant knockdown of gene expression. In vivo studies showed directed delivery of NPSCs to the spleen, enabling gene silencing of macrophages, with preliminary studies showing 70% gene knockdown at a siRNA dose of 0.28 mg/kg. Significantly, the delivery of siRNA targeting tumor necrosis factor-α efficiently silenced TNF-α expression in LPS-challenged mice, demonstrating efficacy in modulating immune response in an organ-selective manner. This research highlights the potential of the NPSC platform for targeted immunotherapy and further manipulation of the immune system. Copyright © 2018 Elsevier B.V. All rights reserved.
Transtuzumab-conjugated liposome-coated fluorscent magnetic namoparticles to target breast cancer

Energy Technology Data Exchange (ETDEWEB)

Jang, Mi Jung; Lee, Hak Jong; Hwang, Sung Il; Yun, Bo La; Kim, Sun Mi [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Yoon, Young Il; Kwon, Yong Soo [Nanoimaging and Therapy Research Center, Institute of Nanoconvergence, Advanced Institutes of Convergence Technology, Seoul National University, Suwon (Korea, Republic of); Yoon, Tae Jong [NanoBio Materials Chemistry Lab., Dept. of Applied Bioscience, CHA University, Pocheon (Korea, Republic of)

2014-08-15

To synthesize mesoporous silica-core-shell magnetic nanoparticles (MNPs) encapsulated by liposomes (Lipo [MNPm-SiO{sub 2}]) in order to enhance their stability, allow them to be used in any buffer solution, and to produce trastuzumab-conjugated (Lipo[MNPm-SiO{sub 2}]-Her2Ab) nanoparticles to be utilized in vitro for the targeting of breast cancer. The physiochemical characteristics of Lipo[MNPm-SiO{sub 2}] were assessed in terms of size, morphological features, and in vitro safety. The multimodal imaging properties of the organic dye incorporated into Lipo[MNPm-SiO{sub 2}] were assessed with both in vitro fluorescence and MR imaging. The specific targeting ability of trastuzumab (Her2/neu antibody, Herceptin)-conjugated Lipo[MNPm-SiO{sub 2}] for Her2/neu-positive breast cancer cells was also evaluated with fluorescence and MR imaging. We obtained uniformly-sized and evenly distributed Lipo[MNPm-SiO{sub 2}] that demonstrated biological stability, while not disrupting cell viability. Her2/neu-positive breast cancer cell targeting by trastuzumab-conjugated Lipo[MNPm-SiO{sub 2}] was observed by in vitro fluorescence and MR imaging. Trastuzumab-conjugated Lipo[MNPm-SiO{sub 2}] is a potential treatment tool for targeted drug delivery in Her2/neu-positive breast cancer.
Growth, characterization, and device development in monocrystalline diamond films

Science.gov (United States)

Davis, Robert F.

1991-12-01

The nucleation of diamond grains on an unscratched silicon wafer is enhanced by four order of magnitude relative to scratched substrates by using negative bias enhanced microwave plasma CVD in a 2 percent methane/hydrogen plasma for an initial period. In vacuo surface analysis has revealed that the actual nucleation occurs on the amorphous C coating present on the thin SiC layer which forms as the product of the initial reaction with the Si surface. It is believed that the C forms critical clusters which are favorable for diamond nucleation. Similar enhancement was observed together with the occurrence of textured diamond films in the use of bias pretreatment of cubic Beta SiC substrates. Approximately 50 percent of the initial diamond nuclei were aligned with the SiC substrate. In contrast, the use of the biasing pretreatment for one hour on polycrystalline substrates resulted in only about 7 percent coverage with diamond particles. Numerous techniques have been used to analyze the nucleation and growth phenomena, especially micro Raman and scanning tunneling microscopy. The latter technique has shown that the morphology of doped and undoped diamond nuclei are similar, as well as the fact that significant concentrations of vacancy related defects are present. In device related-studies, UV-photoemission studies have shown that TiC occurs at the Ti-diamond (100) interface after a 400 C anneal. The Schottky barrier height from this metal on p-type diamond was determined to be 1.0 eV. Indications of negative electron affinity (NEA) was observed and attributed to emission of electrons that are quasi-thermalized to the bottom of the conduction band. A disordered surface removes the NEA. The microwave performance of p-type (beta-doped) diamond MESFET's at 10 GHz has been further investigated. Elevated temperatures may be necessary to obtain sufficient free charge densities in the conducting channel but this will result in degraded device performance. Each of these
SiRNA Crosslinked Nanoparticles for the Treatment of Inflammation-induced Liver Injury.

Science.gov (United States)

Tang, Yaqin; Zeng, Ziying; He, Xiao; Wang, Tingting; Ning, Xinghai; Feng, Xuli

2017-02-01

RNA interference mediated by small interfering RNA (siRNA) provides a powerful tool for gene regulation, and has a broad potential as a promising therapeutic strategy. However, therapeutics based on siRNA have had limited clinical success due to their undesirable pharmacokinetic properties. This study presents pH-sensitive nanoparticles-based siRNA delivery systems (PNSDS), which are positive-charge-free nanocarriers, composed of siRNA chemically crosslinked with multi-armed poly(ethylene glycol) carriers via acid-labile acetal linkers. The unique siRNA crosslinked structure of PNSDS allows it to have minimal cytotoxicity, high siRNA loading efficiency, and a stimulus-responsive property that enables the selective intracellular release of siRNA in response to pH conditions. This study demonstrates that PNSDS can deliver tumor necrosis factor alpha (TNF-α) siRNA into macrophages and induce the efficient down regulation of the targeted gene in complete cell culture media. Moreover, PNSDS with mannose targeting moieties can selectively accumulate in mice liver, induce specific inhibition of macrophage TNF-α expression in vivo, and consequently protect mice from inflammation-induced liver damages. Therefore, this novel siRNA delivering platform would greatly improve the therapeutic potential of RNAi based therapies.
Chitosan-based nanoparticles for survivin targeted siRNA delivery in breast tumor therapy and preventing its metastasis.

Science.gov (United States)

Sun, Ping; Huang, Wei; Jin, Mingji; Wang, Qiming; Fan, Bo; Kang, Lin; Gao, Zhonggao

Nanoparticle-mediated small interfering RNA (siRNA) delivery is a promising therapeutic strategy in various cancers. However, it is difficult to deliver degradative siRNA to tumor tissue, and thus a safe and efficient vector for siRNA delivery is essential for cancer therapy. In this study, poly(ethylene glycol)-modified chitosan (PEG-CS) was synthesized successfully for delivering nucleic acid drug. We deemed that PEGylated CS could improve its solubility by forming a stable siRNA loaded in nanoparticles, and enhancing transfection efficiency of siRNA-loaded CS nanoparticles in cancer cell line. The research results showed that siRNA loaded in PEGylated CS (PEG-CS/siRNA) nanoparticles with smaller particle size had superior structural stability in the physical environment compared to CS nanoparticles. The data of in vitro antitumor activity revealed that 4T1 tumor cell growth was significantly inhibited and cellular uptake of PEG-CS/siRNA nanoparticles in 4T1 cells was dramatically enhanced compared to naked siRNA groups. The results from flow cytometry and confocal laser scanning microscopy showed that PEG-CS/siRNA nanoparticles were more easily taken up than naked siRNA. Importantly, PEG-CS/siRNA nanoparticles significantly reduced the growth of xenograft tumors of 4T1 cells in vivo. It has been demonstrated that the PEG-CS is a safe and efficient vector for siRNA delivery, and it can effectively reduce tumor growth and prevent metastasis.
Structure and optical properties of aSiAl and aSiAlHx magnetron sputtered thin films

Directory of Open Access Journals (Sweden)

Annett Thøgersen

2016-03-01

Full Text Available Thin films of homogeneous mixture of amorphous silicon and aluminum were produced with magnetron sputtering using 2-phase Al–Si targets. The films exhibited variable compositions, with and without the presence of hydrogen, aSi1−xAlx and aSi1−xAlxHy. The structure and optical properties of the films were investigated using transmission electron microscopy, X-ray photoelectron spectroscopy, UV-VisNIR spectrometry, ellipsometry, and atomistic modeling. We studied the effect of alloying aSi with Al (within the range 0–25 at. % on the optical band gap, refractive index, transmission, and absorption. Alloying aSi with Al resulted in a non-transparent film with a low band gap (1 eV. Variations of the Al and hydrogen content allowed for tuning of the optoelectronic properties. The films are stable up to a temperature of 300 °C. At this temperature, we observed Al induced crystallization of the amorphous silicon and the presence of large Al particles in a crystalline Si matrix.
Study of fractal behaviour of target fragments produced in 28Si and 32S emulsion collisions at 14.6 and 200 AGeV

International Nuclear Information System (INIS)

Rasool, Mir Hashim; Ahmad, Shafiq; Ahmad, M. Ayaz

2013-01-01

The experimental data based on 951 and 380 events of 28 Si-emulsion and 32 S-emulsion interactions at 14.6 and 200 AGeV/c respectively have been analysed to investigate intermittent behaviour and fractal properties of emission spectra of fast and slow target associated particles. The observed increasing trend in the values of fractal moments, Fqcorr and modified Gq-moments with decreasing bin size clearly reflects the evaporation model and gives an evidence for an intermittency pattern of fluctuations. The experimental data have been compared with randomly generated uncorrelated Monte Carlo of 10,000 events to check the presence of the statistical fluctuations in the target fragmentation region
Tailoring Lipid and Polymeric Nanoparticles as siRNA Carriers towards the Blood-Brain Barrier – from Targeting to Safe Administration

DEFF Research Database (Denmark)

Gomes, Maria João; Fernandes, Carlos; Martins, Susana

2017-01-01

. The interaction of modified nanoparticles with brain endothelial cells increased 3-fold compared to non-modified lipid nanoparticles, and 4-fold compared to non-modified PLGA nanoparticles, respectively. These nanosystems, which were also demonstrated to be safe for human brain endothelial cells, without...... and efficient delivery to its target, two different nanoparticles platforms, solid lipid (SLN) and poly-lactic-co-glycolic (PLGA) nanoparticles were used in this study. Polymeric PLGA nanoparticles were around 115 nm in size and had 50 % of siRNA association efficiency, while SLN presented 150 nm...
A galactose-functionalized dendritic siRNA-nanovector to potentiate hepatitis C inhibition in liver cells

Science.gov (United States)

Lakshminarayanan, Abirami; Reddy, B. Uma; Raghav, Nallani; Ravi, Vijay Kumar; Kumar, Anuj; Maiti, Prabal K.; Sood, A. K.; Jayaraman, N.; Das, Saumitra

2015-10-01

A RNAi based antiviral strategy holds the promise to impede hepatitis C viral (HCV) infection overcoming the problem of emergence of drug resistant variants, usually encountered in the interferon free direct-acting antiviral therapy. Targeted delivery of siRNA helps minimize adverse `off-target' effects and maximize the efficacy of therapeutic response. Herein, we report the delivery of siRNA against the conserved 5'-untranslated region (UTR) of HCV RNA using a liver-targeted dendritic nano-vector functionalized with a galactopyranoside ligand (DG). Physico-chemical characterization revealed finer details of complexation of DG with siRNA, whereas molecular dynamic simulations demonstrated sugar moieties projecting ``out'' in the complex. Preferential delivery of siRNA to the liver was achieved through a highly specific ligand-receptor interaction between dendritic galactose and the asialoglycoprotein receptor. The siRNA-DG complex exhibited perinuclear localization in liver cells and co-localization with viral proteins. The histopathological studies showed the systemic tolerance and biocompatibility of DG. Further, whole body imaging and immunohistochemistry studies confirmed the preferential delivery of the nucleic acid to mice liver. Significant decrease in HCV RNA levels (up to 75%) was achieved in HCV subgenomic replicon and full length HCV-JFH1 infectious cell culture systems. The multidisciplinary approach provides the `proof of concept' for restricted delivery of therapeutic siRNAs using a target oriented dendritic nano-vector.A RNAi based antiviral strategy holds the promise to impede hepatitis C viral (HCV) infection overcoming the problem of emergence of drug resistant variants, usually encountered in the interferon free direct-acting antiviral therapy. Targeted delivery of siRNA helps minimize adverse `off-target' effects and maximize the efficacy of therapeutic response. Herein, we report the delivery of siRNA against the conserved 5'-untranslated
Structural and optical properties of SiC-SiO2 nanocomposite thin films

Science.gov (United States)

Bozetine, I.; Keffous, A.; Kaci, S.; Menari, H.; Manseri, A.

2018-03-01

This study deals with the deposition of thin films of a SiC-SiO2nanocomposite deposited on silicon substrates. The deposition is carried out by a co-sputtering RF magnetron 13.56 MHz, using two targets a polycristallin 6H-SiC and sprigs of SiO2. In order to study the influence of the deposition time on the morphology, the structural and optical properties of the thin films produced, two series of samples were prepared, namely a series A with a 30 min deposition time and a series B of one hour duration. The samples were investigated using different characterization techniques such as Scanning Electron Microscope (SEM), X-ray Diffraction (DRX), Fourier Transform Infrared Spectroscopy (FTIR), Secondary Ion Mass Spectrometry (SIMS) and photoluminescence. The results obtained, reveal an optical gap varies between 1.4 and 2.4 eV depending on the thickness of the film; thus depending on the deposition time. The SIMS profile recorded the presence of oxygen (16O) on the surface, which the signal beneath the silicon signal (28Si) and carbon (12C) signals, which confirms that the oxide (SiO2) is the first material deposited at the interface film - substrate with an a-OSiC structure. The photoluminescence (PL) measurement exhibits two peaks, centred at 390 nm due to the oxide and at 416 nm due probably to the nanocrystals of SiC crystals, note that when the deposition time increases, the intensity of the PL drops drastically, result in agreement with dense and smooth film.
Bioreducible poly(amido amine)s for siRNA delivery

NARCIS (Netherlands)

van der Aa, L.J.

2011-01-01

Successes in RNA interference based therapies are still limited due to the lack of efficient delivery of the mediator, small interfering RNA (siRNA), to the targeted site. The key to success can be the delivery of the siRNA molecules by polymer-based carrier systems, since they can be chemically
Overcoming cisplatin resistance in non-small cell lung cancer with Mad2 silencing siRNA delivered systemically using EGFR-targeted chitosan nanoparticles.

Science.gov (United States)

Nascimento, Ana Vanessa; Singh, Amit; Bousbaa, Hassan; Ferreira, Domingos; Sarmento, Bruno; Amiji, Mansoor M

2017-01-01

Efficiency of chemotherapy is often limited by low therapeutic index of the drug as well as emergence of inherent and acquired drug resistance in cancer cells. As a common strategy to overcome drug resistance, higher doses of chemo-agents are administered. However, adverse side effects are usually increased as a consequence. A potentially effective approach is to combine chemotherapy with other therapeutic strategies such as small interfering RNAs (siRNAs) that allow the use of lower yet efficient doses of the anticancer drugs. We previously developed epidermal growth factor receptor (EGFR)-targeted chitosan (CS) nanoparticles as a versatile delivery system for silencing the essential mitotic checkpoint gene Mad2, and induce cell death. Here, we tested this system as a single therapy and in combination with cisplatin in cisplatin sensitive and resistant lung cancer models, and characterized its in vivo efficacy and safety. Combination treatment resulted in significant improvement in tumor inhibition that was strikingly more effective in cisplatin-resistant tumors. Importantly, effective cisplatin dosage was dramatically reduced in the co-therapy regimen resulting in negligible toxic effects from the drug as confirmed by parameters such as body weight gain, biochemical markers of hepatic and renal function, and histopathology of liver/kidney/spleen tissues. Overall, we demonstrate that the combination of Mad2 siRNA-loaded CS nanoparticles strategy with chemotherapeutic agents such as cisplatin constitutes an efficient and safe approach for the treatment of drug resistant tumors. Lung cancer remains one of the leading killers in the United States and around the world. Platinum agents, including cisplatin, are the first line treatment in lung cancer, including non-small cell lung cancer (NSCLC), which is the predominant form of lung cancer. In this study, we have evaluated Mad2 cell-cycle checkpoint gene silencing using small interfering RNA (siRNA) delivered
Organization of silicon nanocrystals by localized electrochemical etching

International Nuclear Information System (INIS)

Ayari-Kanoun, Asma; Drouin, Dominique; Beauvais, Jacques; Lysenko, Vladimir; Nychyporuk, Tetyana; Souifi, Abdelkader

2009-01-01

An approach to form a monolayer of organized silicon nanocrystals on a monocrystalline Si wafer is reported. Ordered arrays of nanoholes in a silicon nitride layer were obtained by combining electron beam lithography and plasma etching. Then, a short electrochemical etching current pulse led to formation of a single Si nanocrystal per each nanohole. As a result, high quality silicon nanocrystal arrays were formed with well controlled and reproducible morphologies. In future, this approach can be used to fabricate single electron devices.
Neutron pre-emission at the fusion of 11 Li halo nuclei with Si targets

International Nuclear Information System (INIS)

Petrascu, M.; Isbasescu, A.; Petrascu, H.; Bordeanu, C.; David, I.; Lazar, I.; Mihai, I.; Vaman, G.; Tanihata, I.; Kobayashi, T.; Korsheninnikov, A.; Fukuda, S.; Kumagai, H.; Momota, S.; Ozawa, A.; Yoshida, K.; Nikolski, E.; Giurgiu, M.

1997-01-01

In this contribution, the first experiment on fusion of 11 Li halo nuclei with Si targets is reported. A novel effect consisting of a large neutron pre-emission probability in the fusion process was observed. The neutron halo nuclei are characterized by very large matter radii, small separation energy and small internal momentum of the valence neutrons. Until now, the halo nuclei were investigated mostly by elastic, inelastic scattering and breakup processes. It was recently predicted that due to the very large dimension of 11 Li, one may expect, that in a fusion experiment on a light target, the valence neutrons will not be absorbed together with the 9 Li core, but will be emitted in the early stage of the reaction process. The experiment aiming to check this expectation, performed at RIKEN-RIPS facility, is described. In the experimental arrangement, three main parts are present: the first part contains the detectors used for the control, identification and determination of the beam characteristics; the second part consists of a Multiple Sampling Ionisation Chamber (MUSIC), used for identification of the inclusive evaporation residue spectra produced in the detector-target; the third part consists of two wall neutron detectors, each made up of 15 plastic scintillators. This detector was used for the energy and position determination of the neutrons originating from the target. The projectile energy range was 11.2 - 15.2 AMeV, centered at 13 AMeV. The neutrons resulting from the reaction were measured by time-of-light technique. The position on the 'wall' of the detected neutrons could be also determined. The measured neutron spectra from 11 Li and 9 Li are shown. A marked different between the two spectra was found and it is explained by the contribution of a large amount of pre-emission (breakup) processes, in case of 11 Li projectiles. The position spectra point out the evaporation origin of the neutrons in case of 9 Li projectiles while for 11 Li only the
Direct current magnetron sputtered ZrB{sub 2} thin films on 4H-SiC(0001) and Si(100)

Energy Technology Data Exchange (ETDEWEB)

Tengdelius, Lina, E-mail: lina.tengdelius@liu.se [Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Samuelsson, Mattias [Impact Coatings AB, Westmansgatan 29, SE-582 16 Linköping (Sweden); Jensen, Jens; Lu, Jun; Hultman, Lars; Forsberg, Urban; Janzén, Erik; Högberg, Hans [Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden)

2014-01-01

ZrB{sub 2} thin films have been synthesized using direct current magnetron sputtering from a ZrB{sub 2} compound target onto 4H-SiC(0001) and Si(100) substrates kept at different temperatures (no heating, 400 °C, and 550 °C), and substrate bias voltage (− 20 V to − 80 V). Time-of-flight energy elastic recoil detection analysis shows that all the films are near stoichiometric and have a low degree of contaminants, with O being the most abundant (< 1 at.%). The films are crystalline, and their crystallographic orientation changes from 0001 to a more random orientation with increased deposition temperature. X-ray diffraction pole figures and selected area electron diffraction patterns of the films deposited without heating reveal a fiber-texture growth. Four point probe measurements show typical resistivity values of the films ranging from ∼ 95 to 200 μΩ cm, decreasing with increased growth temperature and substrate bias. - Highlights: • ZrB{sub 2} films have been deposited on 4H-SiC(0001) and Si(100). • Film composition correlates well to that of the target. • Level of contamination in the films is low. • Film resistivity values range from ∼ 95 to 200 μΩ cm.
Topics in LIFE Target Survival: 11-SI-004 Final Report

Energy Technology Data Exchange (ETDEWEB)

Miles, Robin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Benett, Bill [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bond, Tiziana [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chang, Allan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dawson, David [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fornasiero, Francesco [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hamilton, Julie [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Havstad, Mark [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kucheyev, Sergei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); LeBlanc, Mary [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rosso, Paul [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schebler, Greg [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Van Cleve, Eli [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Worsley, Marcus [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-10-20

The LIFE target design incorporates many considerations to generate the desired fusion gain including the physics design, the cost of manufacturing of the target, the injectability of the target, the aerodynamic flight characteristics of the target, the ability to track and engage the target and to maintain the structural and thermal integrity of the target. This document describes the effort that was made in support of issues of survivability of the target during injection which included issues massmanufactural materials and processes which could be used in the target.
Study of Nickel Silicide as a Copper Diffusion Barrier in Monocrystalline Silicon Solar Cells

Energy Technology Data Exchange (ETDEWEB)

Kale, Abhijit; Beese, Emily; Saenz, Theresa; Warren, Emily; Nemeth, William; Young, David; Marshall, Alexander; Florent, Karine; Kurinec, Santosh K.; Agarwal, Sumit; Stradins, Pauls

2016-11-21

NiSi as a conductive diffusion barrier to silicon has been studied. We demonstrate that the NiSi films formed using the single step annealing process are as good as the two step process using XRD and Raman. Quality of NiSi films formed using e-beam Ni and electroless Ni process has been compared. Incomplete surface coverage and presence of constituents other than Ni are the main challenges with electroless Ni. We also demonstrate that Cu reduces the thermal stability of NiSi films. The detection of Cu has proven to be difficult due to temperature limitations.
Electronic-excitation induced radiation damage in glasses

Energy Technology Data Exchange (ETDEWEB)

Vigouroux, J P

1985-01-01

In order to understand the microscopic nature of radiation induced defects in insulators, we have studied localization of negative and positive charges in amorphous and monocrystalline SiO2. The behaviour of these charges is linked to creation of point defects by electronic excitation. The role of intense electric fields under irradiation is pointed out.
Preparation, properties, and application characteristics of metastable layers of the Ti-Si-C-N system

International Nuclear Information System (INIS)

Fella, R.

1992-10-01

In the Ti-Si-C and Ti-Si-C-N systems, metastable layers were precipitated by means of non-reactive magnetron sputtering of hot-pressed two-phase TiC/SiC and TiN/SiC targets with 20 mole% and 50 mole% SiC. The preparation parameters were varied as follows: ion bombardment during precipitation (bias sputtering), substrate temperature, and annealing times when annealing amorphous 50%:50% TiC/SiC and 50%:50% TiN/SiC layers. Sputtering of targets containing 20% SiC was found to result in monophase fcc layers (NaCl structure). This was documented on the basis of X-ray and electron diffraction patterns. Direct precipitation of targets with 50 mole% SiC resulted in amorphous layers. Increasing the ion bombardment during accretion, raising the substrate temperature, and annealing amorphous 50%:50% TiC/SiC and 50%:50% TiN/SiC (layers precipitated directly) resulted in the crystallization of TiC and TiN nanocrystallites, respectively, imbedded in an amorphous SiC matrix. These crystallites were detected both by X-ray and by electron diffractions and by XPS studies. The XPS measurements of crystalline TiC and amorphous SiC reference layers demonstrated the existence of new kinds of carbon interface phases ('pseudocarbide layers') around TiC and amorphous SiC regions, respectively, which have a positive impact on the mechanical properties of the layers. The hardness of the layers can be correlated with the degrees of crystallization and texture. Adhesion and toughness are worse in SiC-bearing layers than PVD TiC and TiN layers, respectively. The application characteristics of the layers were determined by model wear tests relative to 100Cr6 by means of a pin/disk tribometer. N-bearing layers were found to have clearly higher friction coefficients and greater wear than layers without N. (orig.)

Plasma diagnostic studies of the influence of process variables upon the atomic and molecular species ejected from (1-x)Li4SiO4:xLi3PO4 targets during rf-magnetron sputtering

International Nuclear Information System (INIS)

Wachs, A.L.; Bates, J.B.; Dudney, N.J.; Luck, C.F.

1990-01-01

The deposition of thin-film electrolytes is a critical step in the development of lithium microbatteries with the potential for circuit integration. We have performed a preliminary study of the rf-magnetron sputtering of (1-x)Li 4 SiO 4 :xLi 3 PO 4 targets used to deposit amorphous thin-film electrolytes formed of the three-component system Li 2 O--SiO 2 --P 2 O 5 . Mass and optical emission spectroscopies have been used to investigate the effects of target composition and the deposition conditions upon the atomic and molecular species ejected from the targets. The data provide important information for understanding the mechanism of film formation and for monitoring the Li atomic flux onto the substrates during film growth. 5 refs., 7 figs., 1 tab
Ordering at Si(111)/o-Si and Si(111)/SiO2 Interfaces

DEFF Research Database (Denmark)

Robinson, I. K.; Waskiewicz, W. K.; Tung, R. T.

1986-01-01

X-ray diffraction has been used to measure the intensity profile of the two-dimensional rods of scattering from a single interface buried inside a bulk material. In both Si(111)/a-Si and Si(111)/SiO2 examples there are features in the perpendicular-momentum-transfer dependence which are not expec...... are not expected from an ideal sharp interface. The diffraction profiles are explained by models with partially ordered layers extending into the amorphous region. In the Si(111)/a-Si case there is clear evidence of stacking faults which are attributed to residual 7×7 reconstruction....
Photoconductivity relaxation and electron transport in macroporous silicon structures

Directory of Open Access Journals (Sweden)

L.A. Karachevtseva

2017-12-01

Full Text Available Kinetics and temperature dependence of photoconductivity were measured in macroporous silicon at 80…300 K after light illumination with the wavelength 0.9 μm. The influence of mechanisms of the charge carrier transport through the macropore surface barrier on the kinetics of photoconductivity at various temperatures was investigated. The kinetics of photoconductivity distribution in macroporous silicon and Si substrate has been calculated using the finite-difference time-domain method. The maximum of photoconductivity has been found both in the layer of macroporous silicon and in the monocrystalline substrate. The kinetics of photoconductivity distribution in macroporous silicon showed rapid relaxation of the photoconductivity maximum in the layer of macroporous silicon and slow relaxation of it in the monocrystalline substrate.
Tumor responsive targeted multifunctional nanosystems for cancer imaging, chemo- and siRNA therapy

Science.gov (United States)

Savla, Ronak

Cancer is one of the most insidious diseases. Compromising of over 100 different types and sharing the unifying factors of uncontrolled growth and metastasis, unmet clinical needs in terms of cancer diagnosis and treatment continue to exist. It is widely accepted that most forms of cancer are treatable or even curable if detected before widespread metastasis occurs. Nearly a quarter of deaths in the United States is the result of cancer and it only trails heart disease in terms of annual mortality. Surgery, chemotherapy, and radiation therapy are the primary treatment modalities for cancer. Research in these procedures has resulted in substantial benefits for cancer patients, but there is still room for an improvement. However, a time has been reached at which it appears that the benefits from these modalities have been reached the maximum. Therefore, it is vital to develop new strategies for the diagnosis and treatment of cancer. The field of nanotechnology is concerned with structures in the nanometer size range and holds the potential to drastically impact and improve the lives of patients suffering from cancer. Not only can nanotechnology improve current methods of diagnosis and treatment, it has a possibility of introducing newer and better modalities. The overall purpose of this work is to develop novel nanotechnology-based methodologies for the diagnosis and treatment of various forms of cancers. The first aim of the project is the development of a multifunctional targeted nanosystem for the delivery of siRNA to overcome drug resistance. The second aspect is the synthesis of a quantum dot-based delivery system that releases drug in response to pH changes. The third aim is the development of a targeted, tumor environment responsive magnetic resonance nanoparticle contrast agent coupled with a nanoparticle-based treatment.
Intranasal siRNA administration reveals IGF2 deficiency contributes to impaired cognition in Fragile X syndrome mice.

Science.gov (United States)

Pardo, Marta; Cheng, Yuyan; Velmeshev, Dmitry; Magistri, Marco; Eldar-Finkelman, Hagit; Martinez, Ana; Faghihi, Mohammad A; Jope, Richard S; Beurel, Eleonore

2017-03-23

Molecular mechanisms underlying learning and memory remain imprecisely understood, and restorative interventions are lacking. We report that intranasal administration of siRNAs can be used to identify targets important in cognitive processes and to improve genetically impaired learning and memory. In mice modeling the intellectual deficiency of Fragile X syndrome, intranasally administered siRNA targeting glycogen synthase kinase-3β (GSK3β), histone deacetylase-1 (HDAC1), HDAC2, or HDAC3 diminished cognitive impairments. In WT mice, intranasally administered brain-derived neurotrophic factor (BDNF) siRNA or HDAC4 siRNA impaired learning and memory, which was partially due to reduced insulin-like growth factor-2 (IGF2) levels because the BDNF siRNA- or HDAC4 siRNA-induced cognitive impairments were ameliorated by intranasal IGF2 administration. In Fmr1 -/- mice, hippocampal IGF2 was deficient, and learning and memory impairments were ameliorated by IGF2 intranasal administration. Therefore intranasal siRNA administration is an effective means to identify mechanisms regulating cognition and to modulate therapeutic targets.
Production and characterization of Si-N films obtained by r.f. magnetron sputtering

International Nuclear Information System (INIS)

Oliveira, A.; Cavaleiro, A.; Vieira, M.T.

1993-01-01

Si-N films were deposited by sputtering from an Si 3 N 4 target with different deposition pressures and negative substrate bias. The films were amorphous and showed a ''featureless'' morphology. A high oxygen content was detected in unbiased films. For these films the Si/N ratio was very high compared with the target composition, whereas for biased films the opposite was observed. Si-N films presented cohesive failures for loads as high as 21 N and adhesive failure at 45 N when they were analysed by scratch test. Very high hardness (45 GPa) was obtained, particularly for biased films. Unbiased films were softer, which is attributed to the formation of silicon oxide and/or to a lower compressive stress level. (orig.)
Systemic co-delivery of doxorubicin and siRNA using nanoparticles conjugated with EGFR-specific targeting peptide to enhance chemotherapy in ovarian tumor bearing mice

Energy Technology Data Exchange (ETDEWEB)

Liu, C. W.; Lin, W. J., E-mail: wjlin@ntu.edu.tw [National Taiwan University, Graduate Institute of Pharmaceutical Sciences, School of Pharmacy (China)

2013-10-15

This aim of this study was to develop peptide-conjugated nanoparticles (NPs) for systemic co-delivery of siRNA and doxorubicin to enhance chemotherapy in epidermal growth factor receptor (EGFR) high-expressed ovarian tumor bearing mice. The active targeting NPs were prepared using heptapeptide-conjugated poly(d,l-lactic-co-glycolic acid)-poly(ethylene glycol). The particle sizes of peptide-free and peptide-conjugated NPs were 159.3 {+-} 32.5 and 184.0 {+-} 52.9 nm, respectively, with zeta potential -21.3 {+-} 3.8 and -15.3 {+-} 2.8 mV. The peptide-conjugated NPs uptake were more efficient in EGFR high-expressed SKOV3 cells than in EGFR low-expressed HepG2 cells due to heptapeptide specificity. The NPs were used to deliver small molecule anticancer drug (e.g., doxorubicin) and large molecule genetic agent (e.g., siRNA). The IC{sub 50} of doxorubicin-loaded peptide-conjugated NPs (0.09 {+-} 0.06 {mu}M) was significantly lower than peptide-free NPs (5.72 {+-} 2.64 {mu}M). The similar result was observed in siRNA-loaded NPs. The peptide-conjugated NPs not only served as a nanocarrier to efficiently deliver doxorubicin and siRNA to EGFR high-expressed ovarian cancer cells but also increased the intracellular accumulation of the therapeutic agents to induce assured anti-tumor growth effect in vivo.
Preparation of Nb-Si phases by cathode sputtering, in particulat the superconducting phase of epitactically grown A15-Nb3Si

International Nuclear Information System (INIS)

Siefken, U.

1979-01-01

The search for new superconducting materials with high transition temperatures is concentrated on alloys with a cubic A15 structure (Cr 3 Si structure). In this paper we present the preparation of metastable A15-Nb 3 Si which is expected to have a very high transition temperature Tsub(c). The properties of the A15 structure which are relevant for superconductivity are described, in particular the orthogonal chains as the most important structural characteristic, metastability, and the relation between lattice defects and transition temperature. For target compositions of 75% Nb / 25% Si and 80% Nb / 20% Si A15-Nb 3 Si transition temperatures of Tsub(c) = 5.3 K and Tsub(c) = 7.5 K have been measured respectively, with lattice constants asub(o) = 5.19 A and asub(o) = 5.18 A. (orig.) [de
The effect of target and non-target similarity on neural classification performance: A boost from confidence

OpenAIRE

Amar R Marathe; Anthony J Ries; Vernon J Lawhern; Vernon J Lawhern; Brent J Lance; Jonathan eTouryan; Kaleb eMcDowell; Hubert eCecotti

2015-01-01

Brain computer interaction (BCI) technologies have proven effective in utilizing single-trial classification algorithms to detect target images in rapid serial visualization presentation tasks. While many factors contribute to the accuracy of these algorithms, a critical aspect that is often overlooked concerns the feature similarity between target and non-target images. In most real-world environments there are likely to be many shared features between targets and non-targets resulting in si...
The effect of target and non-target similarity on neural classification performance: a boost from confidence

OpenAIRE

Marathe, Amar R.; Ries, Anthony J.; Lawhern, Vernon J.; Lance, Brent J.; Touryan, Jonathan; McDowell, Kaleb; Cecotti, Hubert

2015-01-01

Brain computer interaction (BCI) technologies have proven effective in utilizing single-trial classification algorithms to detect target images in rapid serial visualization presentation tasks. While many factors contribute to the accuracy of these algorithms, a critical aspect that is often overlooked concerns the feature similarity between target and non-target images. In most real-world environments there are likely to be many shared features between targets and non-targets resulting in si...
Investigation of Fe-Si-N films as magnetic overcoat for high density recording disk drives

International Nuclear Information System (INIS)

Gauvin, M.; Talke, F. E.; Fullerton, E. E.

2010-01-01

A 50-nm-thick Fe-Si-N films were deposited via reactive magnetron cosputtering of independent Fe and Si targets, in Ar/N 2 gas mixture, under different dc Fe target power conditions. Magnetic properties, mechanical hardness and tribological properties were characterized as a function of the Fe target power by magnetometry, nanoindentation, and nanoscratch testing, respectively. Deposited samples were found to be ferromagnetic with a coercivity of approximately 20 Oe and a saturation magnetization increasing from 200 to 1100 emu/cm 3 as a function of Fe sputter power, i.e., values typical of soft magnetic materials. The mechanical hardness was found to be between 50% and 70% of the hardness of a pure SiN x film. Nanotribological properties of films deposited with a Fe target power ≥80 W degraded rapidly.
Nanostructures based in boro nitride thin films deposited by PLD onto Si/Si3N4/DLC substrate

International Nuclear Information System (INIS)

Roman, W S; Riascos, H; Caicedo, J C; Ospina, R; Tirado-MejIa, L

2009-01-01

Diamond-like carbon and boron nitride were deposited like nanostructered bilayer on Si/Si 3 N 4 substrate, both with (100) crystallographic orientation, these films were deposited through pulsed laser technique (Nd: YAG: 8 Jcm -2 , 9ns). Graphite (99.99%) and boron nitride (99.99%) targets used to growth the films in argon atmosphere. The thicknesses of bilayer were determined with a perfilometer, active vibration modes were analyzed using infrared spectroscopy (FTIR), finding bands associated around 1400 cm -1 for B - N bonding and bands around 1700 cm -1 associated with C=C stretching vibrations of non-conjugated alkenes and azometinic groups, respectively. The crystallites of thin films were analyzed using X-ray diffraction (XRD) and determinated the h-BN (0002), α-Si 3 N 4 (101) phases. The aim of this study is to relate the dependence on physical and chemical characteristics of the system Si/Si 3 N 4 /DLC/BN with gas pressure adjusted at the 1.33, 2.67 and 5.33 Pa values.
Study of Si/Si, Si/SiO2, and metal-oxide-semiconductor (MOS) using positrons

International Nuclear Information System (INIS)

Leung, To Chi.

1991-01-01

A variable-energy positron beam is used to study Si/Si, Si/SiO 2 , and metal-oxide-semiconductor (MOS) structures. The capability of depth resolution and the remarkable sensitivity to defects have made the positron annihilation technique a unique tool in detecting open-volume defects in the newly innovated low temperature (300C) molecular-beam-epitaxy (MBE) Si/Si. These two features of the positron beam have further shown its potential role in the study of the Si/SiO 2 . Distinct annihilation characteristics has been observed at the interface and has been studied as a function of the sample growth conditions, annealing (in vacuum), and hydrogen exposure. The MOS structure provides an effective way to study the electrical properties of the Si/SiO 2 interface as a function of applied bias voltage. The annihilation characteristics show a large change as the device condition is changed from accumulation to inversion. The effect of forming gas (FG) anneal is studied using positron annihilation and the result is compared with capacitance-voltage (C-V) measurements. The reduction in the number of interface states is found correlated with the changes in the positron spectra. The present study shows the importance of the positron annihilation technique as a non-contact, non-destructive, and depth-sensitive characterization tool to study the Si-related systems, in particular, the Si/SiO 2 interface which is of crucial importance in semiconductor technology, and fundamental understanding of the defects responsible for degradation of the electrical properties
In vivo siRNA delivery system for targeting to the liver by poly-l-glutamic acid-coated lipoplex

Directory of Open Access Journals (Sweden)

Yoshiyuki Hattori

2014-01-01

Full Text Available In this study, we developed anionic polymer-coated liposome/siRNA complexes (lipoplexes with chondroitin sulfate C (CS, poly-l-glutamic acid (PGA and poly-aspartic acid (PAA for siRNA delivery by intravenous injection, and evaluated the biodistribution and gene silencing effect in mice. The sizes of CS-, PGA- and PAA-coated lipoplexes were about 200 nm and their ζ-potentials were negative. CS-, PGA- and PAA-coated lipoplexes did not induce agglutination after mixing with erythrocytes. In terms of biodistribution, siRNAs after intravenous administration of cationic lipoplexes were largely observed in the lungs, but those of CS-, PGA- and PAA-coated lipoplexes were in both the liver and the kidneys, indicating that siRNA might be partially released from the anionic polymer-coated lipoplexes in the blood circulation and accumulate in the kidney, although the lipoplexes can prevent the agglutination with blood components. To increase the association between siRNA and cationic liposome, we used cholesterol-modified siRNA (siRNA-Chol for preparation of the lipoplexes. When CS-, PGA- and PAA-coated lipoplexes of siRNA-Chol were injected into mice, siRNA-Chol was mainly observed in the liver, not in the kidneys. In terms of the suppression of gene expression in vivo, apolipoprotein B (ApoB mRNA in the liver was significantly reduced 48 h after single intravenous injection of PGA-coated lipoplex of ApoB siRNA-Chol (2.5 mg siRNA/kg, but not cationic, CS- and PAA-coated lipoplexes. In terms of toxicity after intravenous injection, CS-, PGA- and PAA-coated lipoplexes did not increase GOT and GPT concentrations in blood. From these findings, PGA coatings for cationic lipoplex of siRNA-Chol might produce a systemic vector of siRNA to the liver.
Strongly nonlinear electronic transport in Cr-Si composite films

International Nuclear Information System (INIS)

Burkov, A.T.; Vinzelberg, H.; Schumann, J.; Nakama, T.; Yagasaki, K.

2004-01-01

The phase formation, the resistivity and the thermopower of amorphous Cr 0.15 Si 0.85 , and nanocrystalline CrSi 2 -Si thin film composites have been studied. The films were produced by a magnetron sputtering of a composite target onto unheated substrates with subsequent crystallization of the film at high temperatures. As the film composite develops under the heat treatment from the initial amorphous state into the final polycrystalline material, two percolation thresholds were found. At first, the percolating cluster of nanocrystalline CrSi 2 is formed. However, this cluster is destroyed with further annealing due to crystallization and redistribution of Si. The composite films which are close to this insulating threshold reveal a strongly nonlinear conductivity. The conductivity increases with the current by two orders of magnitude
Photoluminescence of Er-doped Si-SiO2 and Al-Si-SiO2 sputtered thin films

International Nuclear Information System (INIS)

Rozo, C.; Fonseca, L.F.; Jaque, D.; Sole, J.Garcia

2008-01-01

Er-doped Si-SiO 2 and Al-Si-SiO 2 films have been deposited by rf-sputtering being annealed afterwards. Annealing behavior of the Er 3+ : 4 I 13/2 → 4 I 15/2 emission of Er-doped Si-SiO 2 yields a maximum intensity for annealing at 700-800 deg. C. 4 I 13/2 → 4 I 15/2 peak emission for Er-doped Al-Si-SiO 2 at 1525 nm is shifted from that for Er-doped Si-SiO 2 at 1530 nm and the bandwidth increases from 29 to 42 nm. 4 I 13/2 → 4 I 15/2 emission decays present a fast decaying component related to Er ions coupled to Si nanoparticles, defects, or other ions, and a slow decaying component related to isolated Er ions. Excitation wavelength dependence and excitation power dependence for the 4 I 13/2 → 4 I 15/2 emission correspond with energy transfer from Si nanoparticles. Populating of the 4 I 11/2 level in Er-doped Si-SiO 2 involves branching and energy transfer upconversion involving two or more Er ions. Addition of Al reduces the populating of this level to an energy transfer upconversion involving two ions
Polymer-Mediated Delivery of siRNAs to Hepatocellular Carcinoma: Variables Affecting Specificity and Effectiveness

Directory of Open Access Journals (Sweden)

Rossella Farra

2018-03-01

Full Text Available Despite the advances in anticancer therapies, their effectiveness for many human tumors is still far from being optimal. Significant improvements in treatment efficacy can come from the enhancement of drug specificity. This goal may be achieved by combining the use of therapeutic molecules with tumor specific effects and delivery carriers with tumor targeting ability. In this regard, nucleic acid-based drug (NABD and particularly small interfering RNAs (siRNAs, are attractive molecules due to the possibility to be engineered to target specific tumor genes. On the other hand, polymeric-based delivery systems are emerging as versatile carriers to generate tumor-targeted delivery systems. Here we will focus on the most recent findings in the selection of siRNA/polymeric targeted delivery systems for hepatocellular carcinoma (HCC, a human tumor for which currently available therapeutic approaches are poorly effective. In addition, we will discuss the most attracting and, in our opinion, promising siRNA-polymer combinations for HCC in relation to the biological features of HCC tissue. Attention will be also put on the mathematical description of the mechanisms ruling siRNA-carrier delivery, this being an important aspect to improve effectiveness reducing the experimental work.
Characterization and properties Ti-Al-Si-N nanocomposite coatings prepared by middle frequency magnetron sputtering

Science.gov (United States)

Zou, C. W.; Zhang, J.; Xie, W.; Shao, L. X.; Guo, L. P.; Fu, D. J.

2011-10-01

TiN-containing amorphous Ti-Al-Si-N (nc-TiN/a-Si 3N 4 or a-AlN) nanocomposite coatings were deposited by using a modified closed field twin unbalanced magnetron sputtering system which is arc assisted and consists of two circles of targets, at a substrate temperature of 300 °C. XRD, XPS and High-resolution TEM experiments showed that the coatings contain TiN nanocrystals embedded in the amorphous Si 3N 4 or AlN matrix. The coatings exhibit good mechanical properties that are greatly influenced by the Si contents. The hardness of the Ti-Al-Si-N coatings deposited at Si targets currents of 5, 8, 10, and 12 A were 45, 47, 54 and 46 GPa, respectively. The high hardness of the deposited Ti-Al-Si-N coatings may be own to the plastic distortion and dislocation blocking by the nanocrystalline structure. On the other hand, the friction coefficient decreases monotonously with increasing Si contents. This result would be caused by tribo-chemical reactions, which often take place in many ceramics, e.g. Si 3N 4 reacts with H 2O to produce SiO 2 or Si(OH) 2 tribolay-layer.
Efficient inhibition of fibroblast proliferation and collagen expression by ERK2 siRNAs

International Nuclear Information System (INIS)

Li, Fengfeng; Fan, Cunyi; Cheng, Tao; Jiang, Chaoyin; Zeng, Bingfang

2009-01-01

Transforming growth factor-β1 and fibroblast growth factor-2 play very important roles in fibroblast proliferation and collagen expression. These processes lead to the formation of joint adhesions through the SMAD and MAPK pathways, in which ERK2 is supposed to be crucial. Based on these assumptions, lentivirus (LV)-mediated small interfering RNAs (siRNAs) targeting ERK2 were used to suppress the proliferation and collagen expression of rat joint adhesion tissue fibroblasts (RJATFs). Among four siRNAs examined, siRNA1 caused an 84% reduction in ERK2 expression (p < 0.01) and was selected as the most efficient siRNA for use in this study. In subsequent experiments, significant downregulation of types I and III collagen were observed by quantitative RT-PCR and Western blot analyses. MTT assays and flow cytometry revealed marked inhibition of RJATF proliferation, but no apoptosis. In conclusion, LV-mediated ERK2 siRNAs may represent novel therapies or drug targets for preventing joint adhesion formation.
Ligand-targeted delivery of small interfering RNAs to malignant cells and tissues.

Science.gov (United States)

Thomas, Mini; Kularatne, Sumith A; Qi, Longwu; Kleindl, Paul; Leamon, Christopher P; Hansen, Michael J; Low, Philip S

2009-09-01

Potential clinical applications of small interfering RNA (siRNA) are hampered primarily by delivery issues. We have successfully addressed the delivery problems associated with off-site targeting of highly toxic chemotherapeutic agents by attaching the drugs to tumor-specific ligands that will carry the attached cargo into the desired cancer cell. Indeed, several such tumor-targeted drugs are currently undergoing human clinical trials. We now show that efficient targeting of siRNA to malignant cells and tissues can be achieved by covalent conjugation of small-molecular-weight, high-affinity ligands, such as folic acid and DUPA (2-[3-(1, 3-dicarboxy propyl)-ureido] pentanedioic acid), to siRNA. The former ligand binds a folate receptor that is overexpressed on a variety of cancers, whereas the latter ligand binds to prostate-specific membrane antigen that is overexpressed specifically on prostate cancers and the neovasculature of all solid tumors. Using these ligands, we show remarkable receptor-mediated targeting of siRNA to cancer tissues in vitro and in vivo.

Magnetically targeted delivery of DOX loaded Cu9S5@mSiO2@Fe3O4-PEG nanocomposites for combined MR imaging and chemo/photothermal synergistic therapy

Science.gov (United States)

Liu, Bei; Zhang, Xinyang; Li, Chunxia; He, Fei; Chen, Yinyin; Huang, Shanshan; Jin, Dayong; Yang, Piaoping; Cheng, Ziyong; Lin, Jun

2016-06-01

The combination of multi-theranostic modes in a controlled fashion has received tremendous attention for the construction of cooperative therapeutic systems in nanomedicine. Herein, we have synthesized a smart magnetically targeted nanocarrier system, Cu9S5@mSiO2@Fe3O4-PEG (labelled as CMF), which integrates NIR triggered photothermal therapy, pH/NIR-responsive chemotherapy and MR imaging into one nanoplatform to enhance the therapeutic efficacy. This new multifunctional paradigm has a uniform and monodisperse sesame ball-like structure by decorating tiny Fe3O4 nanoparticles on the surface of Cu9S5@mSiO2 before a further PEG modification to improve its hydrophilicity and biocompatibility. With doxorubicin (DOX) payload, the as-obtained CMF-DOX composites can simultaneously provide an intense heating effect and enhanced DOX release upon 980 nm NIR light exposure, achieving a combined chemo/photothermal therapy. Under the influence of an external magnetic field, the magnetically targeted synergistic therapeutic effect of CMF-DOX can lead to highly superior inhibition of animal H22 tumor in vivo when compared to any of the single approaches alone. The results revealed that this Cu9S5 based magnetically targeted chemo/photothermal synergistic nanocarrier system has great promise in future MR imaging assisted tumor targeted therapy of cancer.
In-beam γ-ray spectroscopy of the neutron rich 39Si

International Nuclear Information System (INIS)

Sohler, D.; Dombradi, Zs.; Achouri, N.L.; Angelique, J.C.; Bastin, B.; Azaiez, F.; Baiborodin, D.; Borcea, R.

2009-01-01

Complete text of publication follows. In order to clarify the role of proton excitations across the Z = 14 subshell closure in neutron-rich Si isotopes, we investigated the structure of the 14 39 Si 25 isotope, having three neutron-hole configurations with respect to an N = 28 core. The excited states of 39 Si were studied by in-beam γ-ray spectroscopy trough fragmentation of radioactive beams. The experiment was performed at the GANIL facility in France. The radioactive beams were produced by the fragmentation of the stable 48 Ca beam of 60 MeV/u energy and 4μA intensity on a 12 C target in the SISSI device. The cocktail beam produced was impinged onto a 9 Be target. The nuclei produced in the secondary fragmentation reaction were selected and unambiguously identified by the SPEG spectrometer. In the performed experiment the 39 Si nuclei were obtained via 1p, 1p1n, 2p1n and 2p2n knockout reactions from the 40,41 P and 42,43 S secondary beams. To measure the γ rays emitted from the excited states, the secondary target was surrounded by the 4π 'Chateau de Crystal' array consisting of 74 BaF 2 scintillators. The γ-ray spectra were generated by gating event-by-event on the incoming secondary beam particles and the ejectiles after the secondary target. For the γ rays emitted by the fast moving fragments accurate Doppler correction was performed. From the obtained γ spectra of 39 Si displayed in Figure 1, two strong γ transitions at 163 and 397 keV as well as weaker ones at 303, 657, 906, 1143 and 1551 keV have been identified. γγ coincidences were obtained in 39 Si after having added all data from the various reaction channels giving rise to 39 Si. Analysing these data the 163 keV transition was found to be in coincidence with the 657, 1143 and 1551 keV ones, but not with the 397 keV transition. The two lines of the 303+397 keV doublet are in mutual coincidence, and one or both of them are found in coincidence with the 906 keV transition.
Multi-task learning for cross-platform siRNA efficacy prediction: an in-silico study.

Science.gov (United States)

Liu, Qi; Xu, Qian; Zheng, Vincent W; Xue, Hong; Cao, Zhiwei; Yang, Qiang

2010-04-10

Gene silencing using exogenous small interfering RNAs (siRNAs) is now a widespread molecular tool for gene functional study and new-drug target identification. The key mechanism in this technique is to design efficient siRNAs that incorporated into the RNA-induced silencing complexes (RISC) to bind and interact with the mRNA targets to repress their translations to proteins. Although considerable progress has been made in the computational analysis of siRNA binding efficacy, few joint analysis of different RNAi experiments conducted under different experimental scenarios has been done in research so far, while the joint analysis is an important issue in cross-platform siRNA efficacy prediction. A collective analysis of RNAi mechanisms for different datasets and experimental conditions can often provide new clues on the design of potent siRNAs. An elegant multi-task learning paradigm for cross-platform siRNA efficacy prediction is proposed. Experimental studies were performed on a large dataset of siRNA sequences which encompass several RNAi experiments recently conducted by different research groups. By using our multi-task learning method, the synergy among different experiments is exploited and an efficient multi-task predictor for siRNA efficacy prediction is obtained. The 19 most popular biological features for siRNA according to their jointly importance in multi-task learning were ranked. Furthermore, the hypothesis is validated out that the siRNA binding efficacy on different messenger RNAs(mRNAs) have different conditional distribution, thus the multi-task learning can be conducted by viewing tasks at an "mRNA"-level rather than at the "experiment"-level. Such distribution diversity derived from siRNAs bound to different mRNAs help indicate that the properties of target mRNA have important implications on the siRNA binding efficacy. The knowledge gained from our study provides useful insights on how to analyze various cross-platform RNAi data for uncovering
Multi-task learning for cross-platform siRNA efficacy prediction: an in-silico study

Directory of Open Access Journals (Sweden)

Xue Hong

2010-04-01

Full Text Available Abstract Background Gene silencing using exogenous small interfering RNAs (siRNAs is now a widespread molecular tool for gene functional study and new-drug target identification. The key mechanism in this technique is to design efficient siRNAs that incorporated into the RNA-induced silencing complexes (RISC to bind and interact with the mRNA targets to repress their translations to proteins. Although considerable progress has been made in the computational analysis of siRNA binding efficacy, few joint analysis of different RNAi experiments conducted under different experimental scenarios has been done in research so far, while the joint analysis is an important issue in cross-platform siRNA efficacy prediction. A collective analysis of RNAi mechanisms for different datasets and experimental conditions can often provide new clues on the design of potent siRNAs. Results An elegant multi-task learning paradigm for cross-platform siRNA efficacy prediction is proposed. Experimental studies were performed on a large dataset of siRNA sequences which encompass several RNAi experiments recently conducted by different research groups. By using our multi-task learning method, the synergy among different experiments is exploited and an efficient multi-task predictor for siRNA efficacy prediction is obtained. The 19 most popular biological features for siRNA according to their jointly importance in multi-task learning were ranked. Furthermore, the hypothesis is validated out that the siRNA binding efficacy on different messenger RNAs(mRNAs have different conditional distribution, thus the multi-task learning can be conducted by viewing tasks at an "mRNA"-level rather than at the "experiment"-level. Such distribution diversity derived from siRNAs bound to different mRNAs help indicate that the properties of target mRNA have important implications on the siRNA binding efficacy. Conclusions The knowledge gained from our study provides useful insights on how to
Additional evaluation of alpha induced neutron production nuclear data. 9Be, 27Al, 28,29,30Si

International Nuclear Information System (INIS)

Murata, Toru; Shibata, Keiichi

2005-01-01

Alpha particle induced neutron production cross sections, emitted neutron energy spectrum and angular distributions were evaluated for the target nucleus 9 Be, 27 Al and Si isotopes; 28 Si, 29 Si and 30 Si in the incident energy region below 15 MeV. (author)
Effects of vibration frequency on vibration-assisted nano-scratch process of mono-crystalline copper via molecular dynamics simulation

Directory of Open Access Journals (Sweden)

Bo Zhu

2016-03-01

Full Text Available It has always been a critical issue to understand the material removal behavior of Vibration-Assisted Machining (VAM, especially on atomic level. To find out the effects of vibration frequency on material removal response, a three-dimensional molecular dynamics (MD model has been established in this research to investigate the effects of scratched groove, crystal defects on the surface quality, comparing with the Von Mises shear strain and tangential force in simulations during nano-scratching process. Comparisons are made among the results of simulations from different vibration frequency with the same scratching feed, depth, amplitude and crystal orientation. Copper potential in this simulation is Embedded-Atom Method (EAM potential. Interaction between copper and carbon atoms is Morse potential. Simulational results show that higher frequency can make groove smoother. Simulation with high frequency creates more dislocations to improve the machinability of copper specimen. The changing frequency does not have evident effects on Von Mises shear strain. Higher frequency can decrease the tangential force to reduce the consumption of cutting energy and tool wear. In conclusion, higher vibration frequency in VAM on mono-crystalline copper has positive effects on surface finish, machinablility and tool wear reduction.
Effects of vibration frequency on vibration-assisted nano-scratch process of mono-crystalline copper via molecular dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Zhu, Bo; Zhao, Hongwei, E-mail: hwzhao@jlu.edu.cn, E-mail: khl69@163.com; Zhao, Dan; Zhang, Peng; Yang, Yihan; Han, Lei [School of Mechanical Science and Engineering, Jilin University, 5988 Renmin Street, Changchun, Jilin 130025 (China); Kui, Hailin, E-mail: hwzhao@jlu.edu.cn, E-mail: khl69@163.com [School of Transportation, Jilin University, 5988 Renmin Street, Changchun, Jilin 130025 (China)

2016-03-15

It has always been a critical issue to understand the material removal behavior of Vibration-Assisted Machining (VAM), especially on atomic level. To find out the effects of vibration frequency on material removal response, a three-dimensional molecular dynamics (MD) model has been established in this research to investigate the effects of scratched groove, crystal defects on the surface quality, comparing with the Von Mises shear strain and tangential force in simulations during nano-scratching process. Comparisons are made among the results of simulations from different vibration frequency with the same scratching feed, depth, amplitude and crystal orientation. Copper potential in this simulation is Embedded-Atom Method (EAM) potential. Interaction between copper and carbon atoms is Morse potential. Simulational results show that higher frequency can make groove smoother. Simulation with high frequency creates more dislocations to improve the machinability of copper specimen. The changing frequency does not have evident effects on Von Mises shear strain. Higher frequency can decrease the tangential force to reduce the consumption of cutting energy and tool wear. In conclusion, higher vibration frequency in VAM on mono-crystalline copper has positive effects on surface finish, machinablility and tool wear reduction.
Overcoming the Challenges of siRNA Delivery: Nanoparticle Strategies.

Science.gov (United States)

Shajari, Neda; Mansoori, Behzad; Davudian, Sadaf; Mohammadi, Ali; Baradaran, Behzad

2017-01-01

Despite therapeutics based on siRNA have an immense potential for the treatment of incurable diseases such as cancers. However, the in vivo utilization of siRNA and also the delivery of this agent to the target site is one of the most controversial challenges. The helpful assistance by nanoparticles can improve stable delivery and also enhance efficacy. More nanoparticle-based siRNA therapeutics is expected to become available in the near future. The search strategy followed the guidelines of the Centre of Reviews and Dissemination. The studies were identified from seven databases (Scopus, Web of Science, Academic Search Premiere, CINAHL, Medline Ovid, Eric and Cochrane Library). Studies was selected based on titles, abstracts and full texts. One hundred twenty nine papers were included in the review. These papers defined hurdles in RNAi delivery and also strategies to overcome these hurdles. This review discussed the existing hurdles for systemic administration of siRNA as therapeutic agents and highlights the various strategies to overcome these hurdles, including lipid-based nanoparticles and polymeric nanoparticles, and we also briefly reviewed chemical modification. Delivery of siRNA to the target site is the biggest challenge for its application in the clinic. The findings of this review confirmed by encapsulation siRNA in the nanoparticles can overcome these challenges. The rapid progress in nanotechnology has enabled the development of effective nanoparticles as the carrier for siRNA delivery. However, our data about siRNA-based therapeutics and also nanomedicine are still limited. More clinical data needs to be completely understood in the benefits and drawbacks of siRNA-based therapeutics. Prospective studies must pay attention to the in vivo safety profiles of the different delivery systems, including uninvited immune system stimulation and cytotoxicity. In essence, the development of nontoxic, biocompatible, and biodegradable delivery systems for
Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiNx/SiNy multilayers

International Nuclear Information System (INIS)

Jiang, Xiaofan; Ma, Zhongyuan; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan

2014-01-01

Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiN x /SiN y multilayers with high on/off ratio of 10 9 . High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.
Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiNx/SiNy multilayers

Science.gov (United States)

Jiang, Xiaofan; Ma, Zhongyuan; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan

2014-09-01

Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiNx/SiNy multilayers with high on/off ratio of 109. High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.
Target preparation

International Nuclear Information System (INIS)

Hinn, G.M.

1984-01-01

A few of the more interesting of the 210 targets prepared in the Laboratory last year are listed. In addition the author continues to use powdered silver mixed with /sup 9,10/BeO to produce sources for accelerator radio dating of Alaskan and South Polar snow. Currently, he is trying to increase production by multiple sample processing. Also the author routinely makes 3 μg/cm 2 cracked slacked carbon stripper foils and is continuing research with some degree of success in making enriched 28 Si targets starting with the oxide
6,7Li + 28Si total reaction cross sections at near barrier energies

International Nuclear Information System (INIS)

Pakou, A.; Musumarra, A.; Pierroutsakou, D.; Alamanos, N.; Assimakopoulos, P.A.; Divis, N.; Doukelis, G.; Gillibert, A.; Harissopulos, S.; Kalyva, G.; Kokkoris, M.; Lagoyannis, A.; Mertzimekis, T.J.; Nicolis, N.G.; Papachristodoulou, C.; Perdikakis, G.; Roubos, D.; Rusek, K.; Spyrou, S.; Zarkadas, Ch.

2007-01-01

Total reaction cross section measurements for the 6,7 Li + 28 Si systems have been performed at near-barrier energies. The results indicate that, with respect to the potential anomaly at barrier, 6 Li and 7 Li on light targets exhibit similar energy dependence on the imaginary potential. Comparisons are made with 6,7 Li cross sections on light and heavy targets, extracted via previous elastic scattering measurements and also with CDCC calculations. Energy dependent parametrisations are also obtained for total reaction cross sections of 6,7 Li on Si, as well as on any target, at near barrier energies
Biocompatible and colloidally stabilized mPEG-PE/calcium phosphate hybrid nanoparticles loaded with siRNAs targeting tumors.

Science.gov (United States)

Gao, Pei; Zhang, Xiangyu; Wang, Hongzhi; Zhang, Qinghong; Li, He; Li, Yaogang; Duan, Yourong

2016-01-19

Calcium phosphate nanoparticles are safe and effective delivery vehicles for small interfering RNA (siRNA), as a result of their excellent biocompatibility. In this work, mPEG-PE (polyethylene glycol-L-α-phosphatidylethanolamine) was synthesized and used to prepare nanoparticles composed of mPEG-PE and calcium phosphate for siRNA delivery. Calcium phosphate and mPEG-PE formed the stable hybrid nanoparticles through self-assembly resulting from electrostatic interaction in water. The average size of the hybrid nanoparticles was approximately 53.2 nm with a negative charge of approximately -16.7 mV, which was confirmed by dynamic light scattering (DLS) measurements. The nanoparticles exhibited excellent stability in serum and could protect siRNA from ribonuclease (RNase) degradation. The cellular internalization of siRNA-loaded nanoparticles was evaluated in SMMC-7721 cells using a laser scanning confocal microscope (CLSM) and flow cytometry. The hybrid nanoparticles could efficiently deliver siRNA to cells compared with free siRNA. Moreover, the in vivo distribution of Cy5-siRNA-loaded hybrid nanoparticles was observed after being injected into tumor-bearing nude mice. The nanoparticles concentrated in the tumor regions through an enhanced permeability and retention (EPR) effect based on the fluorescence intensities of tissue distribution. A safety evaluation of the nanoparticles was performed both in vitro and in vivo demonstrating that the hybrid nanoparticle delivery system had almost no toxicity. These results indicated that the mPEG-PE/CaP hybrid nanoparticles could be a stable, safe and promising siRNA nanocarrier for anticancer therapy.
Enhancement of Spontaneous Erbium Emission near the Photonic Band Edge of Distributed Bragg Reflectors Based on a-Si:H/a-SiOx:H

International Nuclear Information System (INIS)

Medvedev, A.V.; Feoktistov, N.A.; Pevtsov, A.B.; Golubev, V.G.

2005-01-01

Results obtained in an experimental study of spontaneous emission from erbium ions in a spectral range corresponding to the lower photonic band edge of distributed Bragg reflectors (1D photonic crystals) are presented. The photonic crystals were constituted of alternating quarter-wave a-Si:H and a-SiO x :H layers grown by PECVD. Erbium was introduced into the a-Si:H layers by magnetron sputtering of an erbium target in the course of structure growth. The change observed in the intensity of spontaneous emission is due to the nonmonotonic behavior of the density of optical modes near the photonic band edge
Effect of Carbon Concentration on the Sputtering of Carbon-Rich SiC Bombarded by Helium Ions

Directory of Open Access Journals (Sweden)

Xinghao Liang

2018-02-01

Full Text Available Silicon carbide (SiC is considered as an important material for nuclear engineering due to its excellent properties. Changing the carbon content in SiC can regulate and control its elastic and thermodynamic properties, but a simulation study of the effect of carbon content on the sputtering (caused by the helium ions of SiC is still lacking. In this work, we used the Monte-Carlo and molecular dynamics simulation methods to study the effects of carbon concentration, incidence energy, incident angle, and target temperature on the sputtering yield of SiC. The results show that the incident ions’ energy and angle have a significant effect on sputtering yield of SiC when the carbon concentration in SiC is around 62 at %, while the target temperature has a little effect on the sputtering yield of SiC. Our work might provide theoretical support for the experimental research and engineering application of carbon fiber-reinforced SiC that be used as the plasma-facing material in tokamak fusion reactors.
siRNA-loaded cationic liposomes for cancer therapy: Development, characterization and efficacy evaluation

Science.gov (United States)

Ying, Bo

Cancer is a major health problem in the United States and many other parts of the world. However, cancer treatment is severely limited by the lack of highly effective cytotoxic agents and selective delivery methods which can serve as the "magic bullet" (first raised by Dr. Paul Ehrlich, the goal of targeting a specific location without causing harm to surrounding tissues or to more distant regions in the body). The revolutionary finding that tumors cannot grow beyond a microscopic size without dedicated blood supply provided a highly effective alternative for the treatment of cancer. Currently, anti-angiogenic therapy and the discovery of RNA interference makes it possible to treat some conditions by silencing disorder-causing genes of targeting cells which are otherwise difficult to eradicate with more conventional therapies. However, before siRNA technology could be widely used as a therapeutic approach, the construct must be efficiently and safely delivered to target cells. Strategies used for siRNA delivery should minimize uptake by phagocytes, enzymatic degradation by nucleases and should be taken up preferentially, if not specifically, by the intended cell population. Kinesin spindle proteins (KSP) are the motor proteins which play critical roles during mitosis. Different from tubulins which are also present in post-mitotic cells, such as axons, KSP is exclusively expressed in mitotic cells, which makes them the ideal target for anti-mitotics. In the present study, we intend to develop, characterize and evaluate a liposome-based delivery system which can deliver KSP siRNA selectively to the tumor vasculature (thus inhibiting angiogenesis, destroying tumor vasculature and eventually, eradicating tumor growth). We first developed ten different liposome preparation types with different compositions of lipids. Next, the capacity for loading siRNA and efficiency of targeting the tumor vascular supply was evaluated using relevant cellular and tumor models
Electronic states at Si-SiO2 interface introduced by implantation of Si in thermal SiO2

International Nuclear Information System (INIS)

Kalnitsky, A.; Poindexter, E.H.; Caplan, P.J.

1990-01-01

Interface traps due to excess Si introduced into the Si-SiO 2 system by ion implantation are investigated. Implanted oxides are shown to have interface traps at or slightly above the Si conduction band edge with densities proportional to the density of off-stoichiometric Si at the Si-SiO 2 interface. Diluted oxygen annealing is shown to result in physical separation of interface traps and equilibrium substrate electrons, demonstrating that ''interface'' states are located within a 0.5 nm thick layer of SiO 2 . Possible charge trapping mechanisms are discussed and the effect of these traps on MOS transistor characteristics is described using a sheet charge model. (author)
Delivery systems and local administration routes for therapeutic siRNA.

Science.gov (United States)

Vicentini, Fabiana Testa Moura de Carvalho; Borgheti-Cardoso, Lívia Neves; Depieri, Lívia Vieira; de Macedo Mano, Danielle; Abelha, Thais Fedatto; Petrilli, Raquel; Bentley, Maria Vitória Lopes Badra

2013-04-01

With the increasing number of studies proposing new and optimal delivery strategies for the efficacious silencing of gene-related diseases by the local administration of siRNAs, the present review aims to provide a broad overview of the most important and latest developments of non-viral siRNA delivery systems for local administration. Moreover, the main disease targets for the local delivery of siRNA to specific tissues or organs, including the skin, the lung, the eye, the nervous system, the digestive system and the vagina, were explored.
Mechanical Properties And Microstructure Of AlN/SiCN Nanocomposite Coatings Prepared By R.F.-Reactive Sputtering Method

Directory of Open Access Journals (Sweden)

Nakafushi Y.

2015-06-01

Full Text Available FIn this work, AlN/SiCN composite coatings were deposited by r.f.-reactive sputtering method using a facing target-type sputtering (FTS apparatus with composite targets consisting of Al plate and SiC chips in a gaseous mixture of Ar and N2, and investigated their mechanical properties and microstructure. The indentation hardness (HIT of AlN/SiCN coatings prepared from composite targets consisting of 8 ~32 chips of SiC and Al plate showed the maximum value of about 29~32 GPa at a proper nitrogen gas flow rate. X-ray diffraction (XRD patterns for the AlN/SiCN composite coatings indicated the presence of the only peeks of hexagonal (B4 structured AlN phase. AlN coatings clarified the columnar structure of the cross sectional view TEM observation. On the other hand, microstructure of AlN/SiCN composite coatings changed from columnar to equiaxed structure with increasing SiCN content. HR-TEM observation clarified that the composite coatings consisted of very fine equiaxial grains of B4 structured AlN phase and amorphous phase.
Nonvolatile field effect transistors based on protons and Si/SiO2Si structures

International Nuclear Information System (INIS)

Warren, W.L.; Vanheusden, K.; Fleetwood, D.M.; Schwank, J.R.; Winokur, P.S.; Knoll, M.G.; Devine, R.A.B.

1997-01-01

Recently, the authors have demonstrated that annealing Si/SiO 2 /Si structures in a hydrogen containing ambient introduces mobile H + ions into the buried SiO 2 layer. Changes in the H + spatial distribution within the SiO 2 layer were electrically monitored by current-voltage (I-V) measurements. The ability to directly probe reversible protonic motion in Si/SiO 2 /Si structures makes this an exemplar system to explore the physics and chemistry of hydrogen in the technologically relevant Si/SiO 2 structure. In this work, they illustrate that this effect can be used as the basis for a programmable nonvolatile field effect transistor (NVFET) memory that may compete with other Si-based memory devices. The power of this novel device is its simplicity; it is based upon standard Si/SiO 2 /Si technology and forming gas annealing, a common treatment used in integrated circuit processing. They also briefly discuss the effects of radiation on its retention properties

Upright nanopyramid structured cover glass with light harvesting and self-cleaning effects for solar cell applications

International Nuclear Information System (INIS)

Amalathas, Amalraj Peter; Alkaisi, Maan M

2016-01-01

In this paper, we demonstrate the effect of upright nanopyramid (UNP) structured cover glass with light harvesting and self-cleaning functions on the device performance of monocrystalline Si solar cells. The UNP structures were fabricated on the surface of the glass substrate by simple, high throughput and low cost UV nanoimprint lithography, using a Si master mold with inverted nanopyramid (INP) structures. The diffuse transmittance and haze ratio values were significantly increased for UNP patterned glass, especially in the wavelength range 300–600 nm compared to the bare glass; this implies that antireflection and strong light scattering are due to the UNP structures. By replacing a bare cover glass with UNP patterned glass, the power conversion efficiency of the monocrystalline Si solar cell was substantially enhanced by about 10.97%; this is mainly due to the increased short-circuit current density J SC of 32.39 mA cm −2 compared to the reference cell with bare cover glass (i.e. J SC = 31.60 mA cm −2 ). In addition, unlike the bare cover glass (i.e. θ CA ∼ 36°), the fluorinated UNP structured cover glass exhibited a hydrophobic surface with a water contact angle ( θ CA ) of ∼132° and excellent self-cleaning of dust particles by rolling down water droplets. (paper)
Nanostructures based in boro nitride thin films deposited by PLD onto Si/Si{sub 3}N{sub 4}/DLC substrate

Energy Technology Data Exchange (ETDEWEB)

Roman, W S; Riascos, H [Grupo Plasma, Laser y Aplicaciones, Universidad Tecnologica de Pereira (Colombia); Caicedo, J C [Grupo de PelIculas Delgadas, Universidad del Valle, Cali (Colombia); Ospina, R [Laboratorio de Plasma, Universidad Nacional de Colombia, sede Manizales (Colombia); Tirado-MejIa, L, E-mail: hriascos@utp.edu.c [Laboratorio de Optoelectronica, Universidad del Quindio (Colombia)

2009-05-01

Diamond-like carbon and boron nitride were deposited like nanostructered bilayer on Si/Si{sub 3}N{sub 4} substrate, both with (100) crystallographic orientation, these films were deposited through pulsed laser technique (Nd: YAG: 8 Jcm{sup -2}, 9ns). Graphite (99.99%) and boron nitride (99.99%) targets used to growth the films in argon atmosphere. The thicknesses of bilayer were determined with a perfilometer, active vibration modes were analyzed using infrared spectroscopy (FTIR), finding bands associated around 1400 cm{sup -1} for B - N bonding and bands around 1700 cm{sup -1} associated with C=C stretching vibrations of non-conjugated alkenes and azometinic groups, respectively. The crystallites of thin films were analyzed using X-ray diffraction (XRD) and determinated the h-BN (0002), alpha-Si{sub 3}N{sub 4} (101) phases. The aim of this study is to relate the dependence on physical and chemical characteristics of the system Si/Si{sub 3}N{sub 4}/DLC/BN with gas pressure adjusted at the 1.33, 2.67 and 5.33 Pa values.
Signatures of RNA binding proteins globally coupled to effective microRNA target sites

DEFF Research Database (Denmark)

Jacobsen, Anders; Wen, Jiayu; Marks, Debora S

2010-01-01

MicroRNAs (miRNAs) and small interfering RNAs (siRNAs), bound to Argonaute proteins (RISC), destabilize mRNAs through base-pairing with the mRNA. However, the gene expression changes after perturbations of these small RNAs are only partially explained by predicted miRNA/siRNA targeting. Targeting...
Microstructure and mechanical properties of Ti–B–C–N–Si nanocomposite films deposited by unbalanced magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Jang, Jaeho; An, Eunsol; Park, In-Wook; Nam, Dae-Geun [Korea Institute of Industrial Technology (KITECH), Busan, 618-230 (Korea, Republic of); Jo, Ilguk; Lin, Jianliang; Moore, John J. [Advanced Coatings and Surface Engineering Laboratory (ACSEL), Colorado School of Mines, 1500 Illinois St., Golden, Colorado 80401 (United States); Ho Kim, Kwang; Park, Ikmin [School of Materials Science and Engineering, Pusan National University, Busan, 609-735 (Korea, Republic of)

2013-11-15

Quinary Ti–B–C–N–Si nanocomposite thin films were deposited on AISI 304 stainless steel substrates by d.c. unbalanced magnetron sputtering from a TiB{sub 2}–TiC compound target and a pure Si target. The relationship between microstructure and mechanical properties of the films was investigated in terms of the nanosized crystallites/amorphous system. The synthesized Ti–B–C–N–Si films were characterized using x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy, and high resolution transmission electron microscopy. The results showed that the Ti–B–C–N–Si films were nanocomposites composed of nanosized TiB{sub 2}, TiC, and TiSi{sub 2} crystallites (2-3 nm in size) embedded in an amorphous matrix. The addition of Si to the Ti–B–C–N film led to precipitation of nanosized crystalline TiSi{sub 2} and percolation of amorphous SiC phases. The Ti–B–C–N–Si films with up to 7 at. % Si content presented high hardness (≥35 GPa), H/E (≥0.0095), and W{sub e} (>50%) with compressive residual stress (∼0.5 GPa). A systematic investigation on the microstructure and mechanical properties of Ti–B–C–N–Si films containing different Si contents is reported.
Sub-barrier fusion of Si+Si systems

Science.gov (United States)

Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Bourgin, D.; Čolović, P.; Corradi, L.; Courtin, S.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Urbani, M.; Szilner, S.; Zhang, G. L.

2017-11-01

The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC) calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3- excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.
Sub-barrier fusion of Si+Si systems

Directory of Open Access Journals (Sweden)

Colucci G.

2017-01-01

Full Text Available The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3− excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.
Nitric acid oxidation of Si (NAOS) method for low temperature fabrication of SiO{sub 2}/Si and SiO{sub 2}/SiC structures

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, H., E-mail: koba771@ybb.ne.jp [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Agency, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Imamura, K.; Kim, W.-B.; Im, S.-S.; Asuha [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Agency, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

2010-07-15

We have developed low temperature formation methods of SiO{sub 2}/Si and SiO{sub 2}/SiC structures by use of nitric acid, i.e., nitric acid oxidation of Si (or SiC) (NAOS) methods. By use of the azeotropic NAOS method (i.e., immersion in 68 wt% HNO{sub 3} aqueous solutions at 120 deg. C), an ultrathin (i.e., 1.3-1.4 nm) SiO{sub 2} layer with a low leakage current density can be formed on Si. The leakage current density can be further decreased by post-metallization anneal (PMA) at 200 deg. C in hydrogen atmosphere, and consequently the leakage current density at the gate bias voltage of 1 V becomes 1/4-1/20 of that of an ultrathin (i.e., 1.5 nm) thermal oxide layer usually formed at temperatures between 800 and 900 deg. C. The low leakage current density is attributable to (i) low interface state density, (ii) low SiO{sub 2} gap-state density, and (iii) high band discontinuity energy at the SiO{sub 2}/Si interface arising from the high atomic density of the NAOS SiO{sub 2} layer. For the formation of a relatively thick (i.e., {>=}10 nm) SiO{sub 2} layer, we have developed the two-step NAOS method in which the initial and subsequent oxidation is performed by immersion in {approx}40 wt% HNO{sub 3} and azeotropic HNO{sub 3} aqueous solutions, respectively. In this case, the SiO{sub 2} formation rate does not depend on the Si surface orientation. Using the two-step NAOS method, a uniform thickness SiO{sub 2} layer can be formed even on the rough surface of poly-crystalline Si thin films. The atomic density of the two-step NAOS SiO{sub 2} layer is slightly higher than that for thermal oxide. When PMA at 250 deg. C in hydrogen is performed on the two-step NAOS SiO{sub 2} layer, the current-voltage and capacitance-voltage characteristics become as good as those for thermal oxide formed at 900 deg. C. A relatively thick (i.e., {>=}10 nm) SiO{sub 2} layer can also be formed on SiC at 120 deg. C by use of the two-step NAOS method. With no treatment before the NAOS method
Intraventricular Delivery of siRNA Nanoparticles to the Central Nervous System

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Rishab Shyam

2015-01-01

Full Text Available Alzheimer's disease (AD is a progressive neurodegenerative disease currently lacking effective treatment. Efficient delivery of siRNA via nanoparticles may emerge as a viable therapeutic approach to treat AD and other central nervous system disorders. We report here the use of a linear polyethyleneimine (LPEI-g-polyethylene glycol (PEG copolymer-based micellar nanoparticle system to deliver siRNA targeting BACE1 and APP, two therapeutic targets of AD. Using LPEI-siRNA nanoparticles against either BACE1 or APP in cultured mouse neuroblastoma (N2a cells, we observe selective knockdown, respectively, of BACE1 or APP. The encapsulation of siRNA by LPEI-g-PEG carriers, with different grafting degrees of PEG, leads to the formation of micellar nanoparticles with distinct morphologies, including worm-like, rod-like, or spherical nanoparticles. By infusing these shaped nanoparticles into mouse lateral ventricles, we show that rod-shaped nanoparticles achieved the most efficient knockdown of BACE1 in the brain. Furthermore, such knockdown is evident in spinal cords of these treated mice. Taken together, our findings indicate that the shape of siRNA-encapsulated nanoparticles is an important determinant for their delivery and gene knockdown efficiency in the central nervous system.
Molecular-Targeted Immunotherapeutic Strategy for Melanoma via Dual-Targeting Nanoparticles Delivering Small Interfering RNA to Tumor-Associated Macrophages.

Science.gov (United States)

Qian, Yuan; Qiao, Sha; Dai, Yanfeng; Xu, Guoqiang; Dai, Bolei; Lu, Lisen; Yu, Xiang; Luo, Qingming; Zhang, Zhihong

2017-09-26

Tumor-associated macrophages (TAMs) are a promising therapeutic target for cancer immunotherapy. Targeted delivery of therapeutic drugs to the tumor-promoting M2-like TAMs is challenging. Here, we developed M2-like TAM dual-targeting nanoparticles (M2NPs), whose structure and function were controlled by α-peptide (a scavenger receptor B type 1 (SR-B1) targeting peptide) linked with M2pep (an M2 macrophage binding peptide). By loading anti-colony stimulating factor-1 receptor (anti-CSF-1R) small interfering RNA (siRNA) on the M2NPs, we developed a molecular-targeted immunotherapeutic approach to specifically block the survival signal of M2-like TAMs and deplete them from melanoma tumors. We confirmed the validity of SR-B1 for M2-like TAM targeting and demonstrated the synergistic effect of the two targeting units (α-peptide and M2pep) in the fusion peptide (α-M2pep). After being administered to tumor-bearing mice, M2NPs had higher affinity to M2-like TAMs than to tissue-resident macrophages in liver, spleen, and lung. Compared with control treatment groups, M2NP-based siRNA delivery resulted in a dramatic elimination of M2-like TAMs (52%), decreased tumor size (87%), and prolonged survival. Additionally, this molecular-targeted strategy inhibited immunosuppressive IL-10 and TGF-β production and increased immunostimulatory cytokines (IL-12 and IFN-γ) expression and CD8 + T cell infiltration (2.9-fold) in the tumor microenvironment. Moreover, the siRNA-carrying M2NPs down-regulated expression of the exhaustion markers (PD-1 and Tim-3) on the infiltrating CD8 + T cells and stimulated their IFN-γ secretion (6.2-fold), indicating the restoration of T cell immune function. Thus, the dual-targeting property of M2NPs combined with RNA interference provides a potential strategy of molecular-targeted cancer immunotherapy for clinical application.
Joining of SiC ceramics and SiC/SiC composites

Energy Technology Data Exchange (ETDEWEB)

Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1996-08-01

This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method will permit the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent emphasis has been given to technology transfer activities, and several collaborative research efforts are in progress. Investigations are focusing on applying the joining method to sintered {alpha}-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.
Adenovirus-mediated siRNA targeting TNF-α and overexpression of bone morphogenetic protein-2 promotes early osteoblast differentiation on a cell model of Ti particle-induced inflammatory response in vitro

Energy Technology Data Exchange (ETDEWEB)

Guo, H.H.; Yu, C.C.; Sun, S.X. [Affiliated Hospital of Ningxia Medical University, Department of Orthopedic Surgery, Yinchuan (China); Ma, X.J. [Ningxia Medical Autonomous Region of the First People' s Hospital, Department of Orthopedic Surgery, Yinchuan (China); Yang, X.C.; Sun, K.N.; Jin, Q.H. [Affiliated Hospital of Ningxia Medical University, Department of Orthopedic Surgery, Yinchuan (China)

2013-10-02

Wear particles are phagocytosed by macrophages and other inflammatory cells, resulting in cellular activation and release of proinflammatory factors, which cause periprosthetic osteolysis and subsequent aseptic loosening, the most common causes of total joint arthroplasty failure. During this pathological process, tumor necrosis factor-alpha (TNF-α) plays an important role in wear-particle-induced osteolysis. In this study, recombination adenovirus (Ad) vectors carrying both target genes [TNF-α small interfering RNA (TNF-α-siRNA) and bone morphogenetic protein 2 (BMP-2)] were synthesized and transfected into RAW264.7 macrophages and pro-osteoblastic MC3T3-E1 cells, respectively. The target gene BMP-2, expressed on pro-osteoblastic MC3T3-E1 cells and silenced by the TNF-α gene on cells, was treated with titanium (Ti) particles that were assessed by real-time PCR and Western blot. We showed that recombinant adenovirus (Ad-siTNFα-BMP-2) can induce osteoblast differentiation when treated with conditioned medium (CM) containing RAW264.7 macrophages challenged with a combination of Ti particles and Ad-siTNFα-BMP-2 (Ti-ad CM) assessed by alkaline phosphatase activity. The receptor activator of nuclear factor-κB ligand was downregulated in pro-osteoblastic MC3T3-E1 cells treated with Ti-ad CM in comparison with conditioned medium of RAW264.7 macrophages challenged with Ti particles (Ti CM). We suggest that Ad-siTNFα-BMP-2 induced osteoblast differentiation and inhibited osteoclastogenesis on a cell model of a Ti particle-induced inflammatory response, which may provide a novel approach for the treatment of periprosthetic osteolysis.
siRNA associated with immunonanoparticles directed against cd99 antigen improves gene expression inhibition in vivo in Ewing's sarcoma.

Science.gov (United States)

Ramon, A L; Bertrand, J R; de Martimprey, H; Bernard, G; Ponchel, G; Malvy, C; Vauthier, C

2013-07-01

Ewing's sarcoma is a rare, mostly pediatric bone cancer that presents a chromosome abnormality called EWS/Fli-1, responsible for the development of the tumor. In vivo, tumor growth can be inhibited specifically by delivering small interfering RNA (siRNA) associated with nanoparticles. The aim of the work was to design targeted nanoparticles against the cell membrane glycoprotein cd99, which is overexpressed in Ewing's sarcoma cells to improve siRNA delivery to tumor cells. Biotinylated poly(isobutylcyanoacrylate) nanoparticles were conceived as a platform to design targeted nanoparticles with biotinylated ligands and using the biotin-streptavidin coupling method. The targeted nanoparticles were validated in vivo for the targeted delivery of siRNA after systemic administration to mice bearing a tumor model of the Ewing's sarcoma. The expression of the gene responsible of Ewing's sarcoma was inhibited at 78% ± 6% by associating the siRNA with the cd99-targeted nanoparticles compared with an inhibition of only 41% ± 9% achieved with the nontargeted nanoparticles. Copyright © 2013 John Wiley & Sons, Ltd.
Prostate bed target interfractional motion using RTOG consensus definitions and daily CT on rails. Does target motion differ between superior and inferior portions of the clinical target volume

International Nuclear Information System (INIS)

Verma, Vivek; Zhou, Sumin; Enke, Charles A.; Wahl, Andrew O.; Chen, Shifeng

2017-01-01

Using high-quality CT-on-rails imaging, the daily motion of the prostate bed clinical target volume (PB-CTV) based on consensus Radiation Therapy Oncology Group (RTOG) definitions (instead of surgical clips/fiducials) was studied. It was assessed whether PB motion in the superior portion of PB-CTV (SUP-CTV) differed from the inferior PB-CTV (INF-CTV). Eight pT2-3bN0-1M0 patients underwent postprostatectomy intensity-modulated radiotherapy, totaling 300 fractions. INF-CTV and SUP-CTV were defined as PB-CTV located inferior and superior to the superior border of the pubic symphysis, respectively. Daily pretreatment CT-on-rails images were compared to the planning CT in the left-right (LR), superoinferior (SI), and anteroposterior (AP) directions. Two parameters were defined: ''total PB-CTV motion'' represented total shifts from skin tattoos to RTOG-defined anatomic areas; ''PB-CTV target motion'' (performed for both SUP-CTV and INF-CTV) represented shifts from bone to RTOG-defined anatomic areas (i. e., subtracting shifts from skin tattoos to bone). Mean (± standard deviation, SD) total PB-CTV motion was -1.5 (± 6.0), 1.3 (± 4.5), and 3.7 (± 5.7) mm in LR, SI, and AP directions, respectively. Mean (± SD) PB-CTV target motion was 0.2 (±1.4), 0.3 (±2.4), and 0 (±3.1) mm in the LR, SI, and AP directions, respectively. Mean (± SD) INF-CTV target motion was 0.1 (± 2.8), 0.5 (± 2.2), and 0.2 (± 2.5) mm, and SUP-CTV target motion was 0.3 (± 1.8), 0.5 (± 2.3), and 0 (± 5.0) mm in LR, SI, and AP directions, respectively. No statistically significant differences between INF-CTV and SUP-CTV motion were present in any direction. There are no statistically apparent motion differences between SUP-CTV and INF-CTV. Current uniform planning target volume (PTV) margins are adequate to cover both portions of the CTV. (orig.) [de
RNAi phenotype profiling of kinases identifies potential therapeutic targets in Ewing's sarcoma.

Science.gov (United States)

Arora, Shilpi; Gonzales, Irma M; Hagelstrom, R Tanner; Beaudry, Christian; Choudhary, Ashish; Sima, Chao; Tibes, Raoul; Mousses, Spyro; Azorsa, David O

2010-08-18

Ewing's sarcomas are aggressive musculoskeletal tumors occurring most frequently in the long and flat bones as a solitary lesion mostly during the teen-age years of life. With current treatments, significant number of patients relapse and survival is poor for those with metastatic disease. As part of novel target discovery in Ewing's sarcoma, we applied RNAi mediated phenotypic profiling to identify kinase targets involved in growth and survival of Ewing's sarcoma cells. Four Ewing's sarcoma cell lines TC-32, TC-71, SK-ES-1 and RD-ES were tested in high throughput-RNAi screens using a siRNA library targeting 572 kinases. Knockdown of 25 siRNAs reduced the growth of all four Ewing's sarcoma cell lines in replicate screens. Of these, 16 siRNA were specific and reduced proliferation of Ewing's sarcoma cells as compared to normal fibroblasts. Secondary validation and preliminary mechanistic studies highlighted the kinases STK10 and TNK2 as having important roles in growth and survival of Ewing's sarcoma cells. Furthermore, knockdown of STK10 and TNK2 by siRNA showed increased apoptosis. In summary, RNAi-based phenotypic profiling proved to be a powerful gene target discovery strategy, leading to successful identification and validation of STK10 and TNK2 as two novel potential therapeutic targets for Ewing's sarcoma.
Utility of MicroRNAs and siRNAs in Cervical Carcinogenesis

Directory of Open Access Journals (Sweden)

Sacnite del Mar Díaz-González

2015-01-01

Full Text Available MicroRNAs and siRNAs belong to a family of small noncoding RNAs which bind through partial sequence complementarity to 3′-UTR regions of mRNA from target genes, resulting in the regulation of gene expression. MicroRNAs have become an attractive target for genetic and pharmacological modulation due to the critical function of their target proteins in several signaling pathways, and their expression profiles have been found to be altered in various cancers. A promising technology platform for selective silencing of cell and/or viral gene expression using siRNAs is currently in development. Cervical cancer is the most common cancer in women in the developing world and sexually transmitted infection with HPV is the cause of this malignancy. Therefore, a cascade of abnormal events is induced during cervical carcinogenesis, including the induction of genomic instability, reprogramming of cellular metabolic pathways, deregulation of cell proliferation, inhibition of apoptotic mechanisms, disruption of cell cycle control mechanisms, and alteration of gene expression. Thus, in the present review article, we highlight new research on microRNA expression profiles which may be utilized as biomarkers for cervical cancer. Furthermore, we discuss selective silencing of HPV E6 and E7 with siRNAs which represents a potential gene therapy strategy against cervical cancer.
Microstructure and Mechanical Property of SiCf/SiC and Cf/SiC Composites

International Nuclear Information System (INIS)

Lee, S P; Cho, K S; Lee, H U; Lee, J K; Bae, D S; Byun, J H

2011-01-01

The mechanical properties of SiC based composites reinforced with different types of fabrics have been investigated, in conjunction with the detailed analyses of their microstructures. The thermal shock properties of SiC f /SiC composites were also examined. All composites showed a dense morphology in the matrix region. Carbon coated PW-SiC f /SiC composites had a good fracture energy, even if their strength was lower than that of PW-C f /SiC composites. SiC f /SiC composites represented a great reduction of flexural strength at the thermal shock temperature difference of 300 deg. C.
Magnetron-sputter epitaxy of β-FeSi2(220)/Si(111) and β-FeSi2(431)/Si(001) thin films at elevated temperatures

International Nuclear Information System (INIS)

Liu Hongfei; Tan Chengcheh; Chi Dongzhi

2012-01-01

β-FeSi 2 thin films have been grown on Si(111) and Si(001) substrates by magnetron-sputter epitaxy at 700 °C. On Si(111), the growth is consistent with the commonly observed orientation of [001]β-FeSi 2 (220)//[1-10]Si(111) having three variants, in-plane rotated 120° with respect to one another. However, on Si(001), under the same growth conditions, the growth is dominated by [-111]β-FeSi 2 (431)//[110]Si(001) with four variants, which is hitherto unknown for growing β-FeSi 2 . Photoelectron spectra reveal negligible differences in the valance-band and Fe2p core-level between β-FeSi 2 grown on Si(111) and Si(001) but an apparent increased Si-oxidization on the surface of β-FeSi 2 /Si(001). This phenomenon is discussed and attributed to the Si-surface termination effect, which also suggests that the Si/Fe ratio on the surface of β-FeSi 2 (431)/Si(001) is larger than that on the surface of β-FeSi 2 (220)/Si(111).
Targeted co-delivery of Beclin 1 siRNA and FTY720 to hepatocellular carcinoma by calcium phosphate nanoparticles for enhanced anticancer efficacy

Directory of Open Access Journals (Sweden)

Wu JY

2018-03-01

Full Text Available Jun-Yi Wu,1,* Zhong-Xia Wang,1,* Guang Zhang,1 Xian Lu,1 Guang-Hui Qiang,2 Wei Hu,2 An-Lai Ji,3 Jun-Hua Wu,4 Chun-Ping Jiang1 1Department of Hepatobiliary Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu, China; 2Department of Hepatobiliary Surgery, Drum Tower Clinical College of Nanjing Medical University, Nanjing, Jiangsu, China; 3Department of General Surgery, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, Jiangsu, China; 4Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, Jiangsu, China *These authors contributed equally to this work Purpose: FTY720, known as fingolimod, is a new immunosuppressive agent with effective anticancer properties. Although it was recently confirmed that FTY720 inhibits cancer cell proliferation, FTY720 can also induce protective autophagy and reduce cytotoxicity. Blocking autophagy with Beclin 1 siRNA after treatment with FTY720 promotes apoptosis. The objective of this study was to enhance the anticancer effect of FTY720 in hepatocellular carcinoma (HCC by targeted co-delivery of FTY720 and Beclin 1 siRNA using calcium phosphate (CaP nanoparticles (NPs.Materials and methods: First, the siRNA was encapsulated within the CaP core. To form an asymmetric lipid bilayer structure, we then used an anionic lipid for the inner leaflet and a cationic lipid for the outer leaflet; after removing chloroform by rotary evaporation, these lipids were dispersed in a saline solution with FTY720. The NPs were analyzed by transmission electron microscopy, dynamic light scattering and ultraviolet–visible spectrophotometry. Cancer cell viability and cell death were analyzed by MTT assays, fluorescence-activated cell sorting analysis and Western blotting. In addition, the in vivo effects of the NPs were investigated using an athymic nude mouse subcutaneous transplantation tumor model.Results: When the CaP NPs, called
SiC Nanoparticles Toughened-SiC/MoSi2-SiC Multilayer Functionally Graded Oxidation Protective Coating for Carbon Materials at High Temperatures

Science.gov (United States)

Abdollahi, Alireza; Ehsani, Naser; Valefi, Zia; Khalifesoltani, Ali

2017-05-01

A SiC nanoparticle toughened-SiC/MoSi2-SiC functionally graded oxidation protective coating on graphite was prepared by reactive melt infiltration (RMI) at 1773 and 1873 K under argon atmosphere. The phase composition and anti-oxidation behavior of the coatings were investigated. The results show that the coating was composed of MoSi2, α-SiC and β-SiC. By the variations of Gibbs free energy (calculated by HSC Chemistry 6.0 software), it could be suggested that the SiC coating formed at low temperatures by solution-reprecipitation mechanism and at high temperatures by gas-phase reactions and solution-reprecipitation mechanisms simultaneously. SiC nanoparticles could improve the oxidation resistance of SiC/MoSi2-SiC multiphase coating. Addition of SiC nanoparticles increases toughness of the coating and prevents spreading of the oxygen diffusion channels in the coating during the oxidation test. The mass loss and oxidation rate of the SiC nanoparticle toughened-SiC/MoSi2-SiC-coated sample after 10-h oxidation at 1773 K were only 1.76% and 0.32 × 10-2 g/cm3/h, respectively.
Reliability implications of defects in high temperature annealed Si/SiO2/Si structures

International Nuclear Information System (INIS)

Warren, W.L.; Fleetwood, D.M.; Shaneyfelt, M.R.; Winokur, P.S.; Devine, R.A.B.; Mathiot, D.; Wilson, I.H.; Xu, J.B.

1994-01-01

High-temperature post-oxidation annealing of poly-Si/SiO 2 /Si structures such as metal-oxide-semiconductor capacitors and metal-oxide-semiconductor field effect transistors is known to result in enhanced radiation sensitivity, increased 1/f noise, and low field breakdown. The authors have studied the origins of these effects from a spectroscopic standpoint using electron paramagnetic resonance (EPR) and atomic force microscopy. One result of high temperature annealing is the generation of three types of paramagnetic defect centers, two of which are associated with the oxide close to the Si/SiO 2 interface (oxygen-vacancy centers) and the third with the bulk Si substrate (oxygen-related donors). In all three cases, the origin of the defects may be attributed to out-diffusion of O from the SiO 2 network into the Si substrate with associated reduction of the oxide. The authors present a straightforward model for the interfacial region which assumes the driving force for O out-diffusion is the chemical potential difference of the O in the two phases (SiO 2 and the Si substrate). Experimental evidence is provided to show that enhanced hole trapping and interface-trap and border-trap generation in irradiated high-temperature annealed Si/SiO 2 /Si systems are all related either directly, or indirectly, to the presence of oxygen vacancies

2'-OMe-phosphorodithioate-modified siRNAs show increased loading into the RISC complex and enhanced anti-tumour activity.

Science.gov (United States)

Wu, Sherry Y; Yang, Xianbin; Gharpure, Kshipra M; Hatakeyama, Hiroto; Egli, Martin; McGuire, Michael H; Nagaraja, Archana S; Miyake, Takahito M; Rupaimoole, Rajesha; Pecot, Chad V; Taylor, Morgan; Pradeep, Sunila; Sierant, Malgorzata; Rodriguez-Aguayo, Cristian; Choi, Hyun J; Previs, Rebecca A; Armaiz-Pena, Guillermo N; Huang, Li; Martinez, Carlos; Hassell, Tom; Ivan, Cristina; Sehgal, Vasudha; Singhania, Richa; Han, Hee-Dong; Su, Chang; Kim, Ji Hoon; Dalton, Heather J; Kovvali, Chandra; Keyomarsi, Khandan; McMillan, Nigel A J; Overwijk, Willem W; Liu, Jinsong; Lee, Ju-Seog; Baggerly, Keith A; Lopez-Berestein, Gabriel; Ram, Prahlad T; Nawrot, Barbara; Sood, Anil K

2014-03-12

Improving small interfering RNA (siRNA) efficacy in target cell populations remains a challenge to its clinical implementation. Here, we report a chemical modification, consisting of phosphorodithioate (PS2) and 2'-O-Methyl (2'-OMe) MePS2 on one nucleotide that significantly enhances potency and resistance to degradation for various siRNAs. We find enhanced potency stems from an unforeseen increase in siRNA loading to the RNA-induced silencing complex, likely due to the unique interaction mediated by 2'-OMe and PS2. We demonstrate the therapeutic utility of MePS2 siRNAs in chemoresistant ovarian cancer mouse models via targeting GRAM domain containing 1B (GRAMD1B), a protein involved in chemoresistance. GRAMD1B silencing is achieved in tumours following MePS2-modified siRNA treatment, leading to a synergistic anti-tumour effect in combination with paclitaxel. Given the previously limited success in enhancing siRNA potency with chemically modified siRNAs, our findings represent an important advance in siRNA design with the potential for application in numerous cancer types.
The Polerovirus silencing suppressor P0 targets ARGONAUTE proteins for degradation.

Science.gov (United States)

Baumberger, Nicolas; Tsai, Ching-Hsui; Lie, Miranda; Havecker, Ericka; Baulcombe, David C

2007-09-18

Plant and animal viruses encode suppressor proteins of an adaptive immunity mechanism in which viral double-stranded RNA is processed into 21-25 nt short interfering (si)RNAs. The siRNAs guide ARGONAUTE (AGO) proteins so that they target viral RNA. Most viral suppressors bind long dsRNA or siRNAs and thereby prevent production of siRNA or binding of siRNA to AGO. The one exception is the 2b suppressor of Cucumoviruses that binds to and inhibits AGO1. Here we describe a novel suppressor mechanism in which a Polerovirus-encoded F box protein (P0) targets the PAZ motif and its adjacent upstream sequence in AGO1 and mediates its degradation. F box proteins are components of E3 ubiquitin ligase complexes that add polyubiquitin tracts on selected lysine residues and thereby mark a protein for proteasome-mediated degradation. With P0, however, the targeted degradation of AGO is insensitive to inhibition of the proteasome, indicating that the proteasome is not involved. We also show that P0 does not block a mobile signal of silencing, indicating that the signal molecule does not have AGO protein components. The ability of P0 to block silencing without affecting signal movement may contribute to the phloem restriction of viruses in the Polerovirus group.
Development of a Positive-readout Mouse Model of siRNA Pharmacodynamics

Directory of Open Access Journals (Sweden)

Mark Stevenson

2013-01-01

Full Text Available Development of RNAi-based therapeutics has the potential to revolutionize treatment options for a range of human diseases. However, as with gene therapy, a major barrier to progress is the lack of methods to achieve and measure efficient delivery for systemic administration. We have developed a positive-readout pharmacodynamic transgenic reporter mouse model allowing noninvasive real-time assessment of siRNA activity. The model combines a luciferase reporter gene under the control of regulatory elements from the lac operon of Escherichia coli. Introduction of siRNA targeting lac repressor results in increased luciferase expression in cells where siRNA is biologically active. Five founder luciferase-expressing and three founder Lac-expressing lines were generated and characterized. Mating of ubiquitously expressing luciferase and lac lines generated progeny in which luciferase expression was significantly reduced compared with the parental line. Administration of isopropyl β-D-1-thiogalactopyranoside either in drinking water or given intraperitoneally increased luciferase expression in eight of the mice examined, which fell rapidly when withdrawn. Intraperitoneal administration of siRNA targeting lac in combination with Lipofectamine 2000 resulted in increased luciferase expression in the liver while control nontargeting siRNA had no effect. We believe a sensitive positive readout pharmacodynamics reporter model will be of use to the research community in RNAi-based vector development.
Fabrication and Mechanical Properties of SiCw(p/SiC-Si Composites by Liquid Si Infiltration using Pyrolysed Rice Husks and SiC Powders as Precursors

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Dan Zhu

2014-03-01

Full Text Available Dense silicon carbide (SiC matrix composites with SiC whiskers and particles as reinforcement were prepared by infiltrating molten Si at 1550 °C into porous preforms composed of pyrolysed rice husks (RHs and extra added SiC powder in different ratios. The Vickers hardness of the composites showed an increase from 18.6 to 21.3 GPa when the amount of SiC added in the preforms was 20% (w/w, and then decreased to 17.3 GPa with the increase of SiC added in the preforms up to 80% (w/w. The values of flexural strength of the composites initially decreased when 20% (w/w SiC was added in the preform and then increased to 587 MPa when the SiC concentration reached 80% (w/w. The refinement of SiC particle sizes and the improvement of the microstructure in particle distribution of the composites due to the addition of external SiC played an effective role in improving the mechanical properties of the composites.
Neurobasal media facilitates increased specificity of siRNA-mediated knockdown in primary cerebellar cultures

DEFF Research Database (Denmark)

Gustafsson, Julie Ry; Katsioudi, Georgia; Issazadeh-Navikas, Shohreh

2016-01-01

be effectively grown in Neurobasal™ media. NEW METHOD: We tested the efficiency of siRNA from the Accell range from Dharmacon™ when delivered in Neurobasal™ media in contrast to the recommended Accell Delivery media provided by the manufacturer. RESULTS: We observed a more specific knockdown of target...... in Neurobasal™ media, than in Accell Delivery media when using cerebellar granule neurons. Transfection efficiency and cell viability was comparable between the two media. COMPARISON WITH EXISTING METHODS: Delivery of siRNA in Neurobasal™ media facilitates increased specificity of the knockdown compared...... to delivery in Accell Delivery media. The off-target effect observed in Accell Delivery media was not a secondary biological response to downregulation of target, but rather a mixture of specific and non-specific off-target effects. CONCLUSIONS: Specific knockdown of target can be achieved in primary...
Polo-like kinase 1 siRNA-607 induces mitotic arrest and apoptosis in ...

African Journals Online (AJOL)

Polo-like kinase (Plk) 1 is overexpressed in many human malignancies including nasopharyngeal carcinoma, indicating its potential as a therapeutic target. Recently, using a simple cellular morphologybased strategy, we have identified several novel effective siRNAs against Plk1 including Plk1 siRNA- 607. In this study, we ...
Oscillations in the fusion of the Si + Si systems; Oscilaciones en la fusion de sistemas de Si + Si

Energy Technology Data Exchange (ETDEWEB)

Aguilera R, E F; Kolata, J J; DeYoung, P A; Vega, J J [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

1986-02-15

Excitation functions for the yields of all the residual nuclei from the {sup 28} Si + {sup 28,30} and {sup 30} Si + {sup 30} Si reactions have been measured via the {gamma}-ray technique for center of mass energies in the region within one and two times the Coulomb barrier.Thirteen elements were identified for the first reaction and ten for the other two. While no structure is shown by the data for the {sup 28} + {sup 28} Si reaction, we have found evidence for intermediate width structure in the 2{alpha} and the {alpha}pn channels in {sup 28} Si + {sup 30} Si and for broad structure in the total fusion cross sections for {sup 30} Si + {sup 30} Si. Calculations using a barrier penetration model with one free parameter reproduce the experimental results quite well. Evaporation model calculations indicate that the individual structure of the nuclei involved in the respective decay chains might have an important influence upon the deexcitation process at the energies relevant to our experiments. (Author)
A new material platform of Si photonics for implementing architecture of dense wavelength division multiplexing on Si bulk wafer

Science.gov (United States)

Zhang, Ziyi; Yako, Motoki; Ju, Kan; Kawai, Naoyuki; Chaisakul, Papichaya; Tsuchizawa, Tai; Hikita, Makoto; Yamada, Koji; Ishikawa, Yasuhiko; Wada, Kazumi

2017-12-01

A new materials group to implement dense wavelength division multiplexing (DWDM) in Si photonics is proposed. A large thermo-optic (TO) coefficient of Si malfunctions multiplexer/demultiplexer (MUX/DEMUX) on a chip under thermal fluctuation, and thus DWDM implementation, has been one of the most challenging targets in Si photonics. The present study specifies an optical materials group for DWDM by a systematic survey of their TO coefficients and refractive indices. The group is classified as mid-index contrast optics (MiDex) materials, and non-stoichiometric silicon nitride (SiNx) is chosen to demonstrate its significant thermal stability. The TO coefficient of non-stoichiometric SiNx is precisely measured in the temperature range 24-76 °C using the SiNx rings prepared by two methods: chemical vapor deposition (CVD) and physical vapor deposition (PVD). The CVD-SiNx ring reveals nearly the same TO coefficient reported for stoichiometric CVD-Si3N4, while the value for the PVD-SiNx ring is slightly higher. Both SiNx rings lock their resonance frequencies within 100 GHz in this temperature range. Since CVD-SiNx needs a high temperature annealing to reduce N-H bond absorption, it is concluded that PVD-SiNx is suited as a MiDex material introduced in the CMOS back-end-of-line. Further stabilization is required, considering the crosstalk between two channels; a 'silicone' polymer is employed to compensate for the temperature fluctuation using its negative TO coefficient, called athermalization. This demonstrates that the resonance of these SiNx rings is locked within 50 GHz at the same temperature range in the wavelength range 1460-1620 nm (the so-called S, C, and L bands in optical fiber communication networks). A further survey on the MiDex materials strongly suggests that Al2O3, Ga2O3 Ta2O5, HfO2 and their alloys should provide even more stable platforms for DWDM implementation in MiDex photonics. It is discussed that the MiDex photonics will find various applications
A new material platform of Si photonics for implementing architecture of dense wavelength division multiplexing on Si bulk wafer.

Science.gov (United States)

Zhang, Ziyi; Yako, Motoki; Ju, Kan; Kawai, Naoyuki; Chaisakul, Papichaya; Tsuchizawa, Tai; Hikita, Makoto; Yamada, Koji; Ishikawa, Yasuhiko; Wada, Kazumi

2017-01-01

A new materials group to implement dense wavelength division multiplexing (DWDM) in Si photonics is proposed. A large thermo-optic (TO) coefficient of Si malfunctions multiplexer/demultiplexer (MUX/DEMUX) on a chip under thermal fluctuation, and thus DWDM implementation, has been one of the most challenging targets in Si photonics. The present study specifies an optical materials group for DWDM by a systematic survey of their TO coefficients and refractive indices. The group is classified as mid-index contrast optics (MiDex) materials, and non-stoichiometric silicon nitride (SiN x ) is chosen to demonstrate its significant thermal stability. The TO coefficient of non-stoichiometric SiN x is precisely measured in the temperature range 24-76 °C using the SiN x rings prepared by two methods: chemical vapor deposition (CVD) and physical vapor deposition (PVD). The CVD-SiN x ring reveals nearly the same TO coefficient reported for stoichiometric CVD-Si 3 N 4 , while the value for the PVD-SiN x ring is slightly higher. Both SiN x rings lock their resonance frequencies within 100 GHz in this temperature range. Since CVD-SiN x needs a high temperature annealing to reduce N-H bond absorption, it is concluded that PVD-SiN x is suited as a MiDex material introduced in the CMOS back-end-of-line. Further stabilization is required, considering the crosstalk between two channels; a 'silicone' polymer is employed to compensate for the temperature fluctuation using its negative TO coefficient, called athermalization. This demonstrates that the resonance of these SiN x rings is locked within 50 GHz at the same temperature range in the wavelength range 1460-1620 nm (the so-called S, C, and L bands in optical fiber communication networks). A further survey on the MiDex materials strongly suggests that Al 2 O 3 , Ga 2 O 3 Ta 2 O 5 , HfO 2 and their alloys should provide even more stable platforms for DWDM implementation in MiDex photonics. It is discussed that the MiDex photonics
Analyses of the As doping of SiO{sub 2}/Si/SiO{sub 2} nanostructures

Energy Technology Data Exchange (ETDEWEB)

Ruffino, Francesco; Miritello, Maria [CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Tomasello, Mario Vincenzo [Scuola Superiore di Catania, via San Nullo 5/i, 95123 Catania (Italy); De Bastiani, Riccardo; Grimaldi, Maria Grazia [Dipartimento di Fisica ed Astronomia, Universita di Catania, via S. Sofia 64, 95123 Catania (Italy); CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Nicotra, Giuseppe; Spinella, Corrado [Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM), VIII Strada 5, 95121 Catania (Italy)

2011-03-15

We illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO{sub 2}(70nm)/Si(30nm)/SiO{sub 2}(70nm) multilayer and its spatial redistribution when annealing processes are performed. By Rutherford backscattering spectrometry and Z-contrast transmission electron microscopy we found an As accumulation at the Si/SiO{sub 2} interfaces and at the Si grain boundaries with no segregation of the As in the Si layer. Such an effect is in agreement with a model that assumes a traps distribution in the Si in the first 2-3 nm above the SiO{sub 2}/Si interfaces and along the Si grain boundaries. The traps concentration at the Si/SiO{sub 2} interfaces was estimated in 10{sup 14} traps/cm{sup 2}. The outlined results can open perspectives on the doping properties of As in Si nanocrystals, whose applications in nanoelectronics and optoelectronics are widely investigated (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiN{sub x}/SiN{sub y} multilayers

Energy Technology Data Exchange (ETDEWEB)

Jiang, Xiaofan; Ma, Zhongyuan, E-mail: zyma@nju.edu.cn; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan [National Laboratory of Solid State Microstructures, Jiangsu Provincial Key Laboratory of Photonic Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

2014-09-28

Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiN{sub x}/SiN{sub y} multilayers with high on/off ratio of 10{sup 9}. High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.
Platinum Interference with siRNA Non-seed Regions Fine-Tunes Silencing Capacity

DEFF Research Database (Denmark)

Hedman, Hanna K; Kirpekar, Finn; Elmroth, Sofi K C

2011-01-01

expression, and the other one focused on the function of endogenous miRNAs. In both cases, the active molecule consists of a ∼20-nucleotide-long RNA duplex. In the siRNA case, improved systemic stability is of central interest for its further development toward clinical applications. With respect to mi......RNA processing and function, understanding its influence on mRNA targeting and the silencing ability of individual miRNAs, e.g., under pathological conditions, remains a scientific challenge. In the present study, a model system is presented where the influence of the two clinically used anticancer drugs......, cisplatin and oxaliplatin, on siRNA's silencing capacity has been evaluated. More specifically, siRNAs targeting the 3' UTR region of Wnt-5a mRNA (NM_003352) were constructed, and the biologically active antisense RNA strand was pre-platinated. Platinum adducts were detected and characterized...
An extended five-stream model for diffusion of ion-implanted dopants in monocrystalline silicon

International Nuclear Information System (INIS)

Khina, B.B.

2007-01-01

Low-energy high-dose ion implantation of different dopants (P, Sb, As, B and others) into monocrystalline silicon with subsequent thermal annealing is used for the formation of ultra-shallow p-n junctions in modern VLSI circuit technology. During annealing, dopant activation and diffusion in silicon takes place. The experimentally observed phenomenon of transient enhanced diffusion (TED), which is typically ascribed to the interaction of diffusing species with non-equilibrium point defects accumulated in silicon due to ion damage, and formation of small clusters and extended defects, hinders further down scaling of p-n junctions in VLSI circuits. TED is currently a subject of extensive experimental and theoretical investigation in many binary and multicomponent systems. However, the state-of-the-art mathematical models of dopant diffusion, which are based on the so-called 'five-stream' approach, and modern TCAD software packages such as SUPREM-4 (by Silvaco Data Systems, Ltd.) that implement these models encounter severe difficulties in describing TED. Solving the intricate problem of TED suppression and development of novel regimes of ion implantation and rapid thermal annealing is impossible without elaboration of new mathematical models and computer simulation of this complex phenomenon. In this work, an extended five-stream model for diffusion in silicon is developed which takes into account all possible charge states of point defects (vacancies and silicon self-interstitials) and diffusing pairs 'dopant atom-vacancy' and 'dopant atom-silicon self-interstitial'. The model includes the drift terms for differently charged point defects and pairs in the internal electric field and the kinetics of interaction between unlike 'species' (generation and annihilation of pairs and annihilation of point defects). Expressions for diffusion coefficients and numerous sink/source terms that appear in the non-linear, non-steady-state reaction-diffusion equations are derived
Inhibition of Hepatitis B virus cccDNA replication by siRNA

International Nuclear Information System (INIS)

Li Guiqiu; Gu Hongxi; Li Di; Xu Weizhen

2007-01-01

The development of an effective therapy for Hepatitis B virus (HBV) infection is still a challenge. Progress in RNA interference (RNAi) has shed slight on developing a new anti-HBV strategy. Here, we present a series of experiments showing a significant reduction in HBV transcripts and replication intermediates in HepG2.2.15 cells by vector-based siRNA targeted nuclear localization signal (NLS) region. More importantly, we showed that siRNA1 markedly inhibited HBV covalently closed circular DNA (cccDNA) replication. Our results indicated that HBV NLS may serve as a novel RNAi target to combat HBV infection, which can enhance anti-HBV efficacy and overcome the drawbacks of current therapies
Pulmonary Delivery of siRNA via Polymeric Vectors as Therapies of Asthma.

Science.gov (United States)

Xie, Yuran; Merkel, Olivia M

2015-10-01

Asthma is a chronic inflammatory disease. Despite the fact that current therapies, such as the combination of inhaled corticosteroids and β2-agonists, can control the symptoms of asthma in most patients, there is still an urgent need for an alternative anti-inflammatory therapy for patients who suffer from severe asthma but lack acceptable response to conventional therapies. Many molecular factors are involved in the inflammatory process in asthma, and thus blocking the function of these factors could efficiently alleviate airway inflammation. RNA interference (RNAi) is often thought to be the answer in the search for more efficient and biocompatible treatments. However, difficulties of efficient delivery of small interference RNA (siRNA), the key factor in RNAi, to target cells and tissues have limited its clinical application. In this review, we summarize cytokines and chemokines, transcription factors, tyrosine kinases, and costimulatory factors that have been reported as targets of siRNA-mediated treatment in experimental asthma. Additionally, we conclude several targeted delivery systems of siRNA to specific cells such as T cells, macrophages, and dendritic cells, which could potentially be applied in asthma therapy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Strained Si/SiGe MOS transistor model

Directory of Open Access Journals (Sweden)

Tatjana Pešić-Brđanin

2009-06-01

Full Text Available In this paper we describe a new model of surfacechannel strained-Si/SiGe MOSFET based on the extension of non-quasi-static (NQS circuit model previously derived for bulk-Si devices. Basic equations of the NQS model have been modified to account for the new physical parameters of strained-Si and relaxed-SiGe layers. From the comparisons with measurements, it is shown that a modified NQS MOS including steady-state self heating can accurately predict DC characteristics of Strained Silicon MOSFETs.
3 to 15 keV Ar+ induced Auger electron emission from Si and Ar

International Nuclear Information System (INIS)

Kempf, J.; Kaus, G.

1977-01-01

Ar + induced Auger electrons from Si and Ar were investigated at bombardment energies between 3-15 keV and target currents of a few μA. The Auger electron yields were compared with secondary ion yields of Si and Ar by simultaneous SIMS-AES measurements. In the ion induced Auger spectra of Si five Auger peaks and in the Ar spectra three Auger peaks were observed. The ion induced Auger electron yield of Si and Ar were found to be strongly dependent upon the primary ion energy. 'Bulk like' and 'atomic like' Auger transitions of ion induced Auger electrons of Si were observed. (orig.) [de
Effect of hydrogen on passivation quality of SiNx/Si-rich SiNx stacked layers deposited by catalytic chemical vapor deposition on c-Si wafers

International Nuclear Information System (INIS)

Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke; Matsumura, Hideki

2015-01-01

We investigate the role of hydrogen content and fixed charges of catalytic chemical vapor deposited (Cat-CVD) SiN x /Si-rich SiN x stacked layers on the quality of crystalline silicon (c-Si) surface passivation. Calculated density of fixed charges is on the order of 10 12 cm −2 , which is high enough for effective field effect passivation. Hydrogen content in the films is also found to contribute significantly to improvement in passivation quality of the stacked layers. Furthermore, Si-rich SiN x films deposited with H 2 dilution show better passivation quality of SiN x /Si-rich SiN x stacked layers than those prepared without H 2 dilution. Effective minority carrier lifetime (τ eff ) in c-Si passivated by SiN x /Si-rich SiN x stacked layers is as high as 5.1 ms when H 2 is added during Si-rich SiN x deposition, which is much higher than the case of using Si-rich SiN x films prepared without H 2 dilution showing τ eff of 3.3 ms. - Highlights: • Passivation mechanism of Si-rich SiN x /SiN x stacked layers is investigated. • H atoms play important role in passivation quality of the stacked layer. • Addition of H 2 gas during Si-rich SiN x film deposition greatly enhances effective minority carrier lifetime (τ eff ). • For a Si-rich SiN x film with refractive index of 2.92, τ eff improves from 3.3 to 5.1 ms by H 2 addition
Enrichment of intersubtype HIV-1 recombinants in a dual infection system using HIV-1 strain-specific siRNAs

Science.gov (United States)

2011-01-01

Background Intersubtype HIV-1 recombinants in the form of unique or stable circulating recombinants forms (CRFs) are responsible for over 20% of infections in the worldwide epidemic. Mechanisms controlling the generation, selection, and transmission of these intersubtype HIV-1 recombinants still require further investigation. All intersubtype HIV-1 recombinants are generated and evolve from initial dual infections, but are difficult to identify in the human population. In vitro studies provide the most practical system to study mechanisms, but the recombination rates are usually very low in dual infections with primary HIV-1 isolates. This study describes the use of HIV-1 isolate-specific siRNAs to enrich intersubtype HIV-1 recombinants and inhibit the parental HIV-1 isolates from a dual infection. Results Following a dual infection with subtype A and D primary HIV-1 isolates and two rounds of siRNA treatment, nearly 100% of replicative virus was resistant to a siRNA specific for an upstream target sequence in the subtype A envelope (env) gene as well as a siRNA specific for a downstream target sequence in the subtype D env gene. Only 20% (10/50) of the replicating virus had nucleotide substitutions in the siRNA-target sequence whereas the remaining 78% (39/50) harbored a recombination breakpoint that removed both siRNA target sequences, and rendered the intersubtype D/A recombinant virus resistant to the dual siRNA treatment. Since siRNAs target the newly transcribed HIV-1 mRNA, the siRNAs only enrich intersubtype env recombinants and do not influence the recombination process during reverse transcription. Using this system, a strong bias is selected for recombination breakpoints in the C2 region, whereas other HIV-1 env regions, most notably the hypervariable regions, were nearly devoid of intersubtype recombination breakpoints. Sequence conservation plays an important role in selecting for recombination breakpoints, but the lack of breakpoints in many conserved
Dual-Functionalized Graphene Oxide Based siRNA Delivery System for Implant Surface Biomodification with Enhanced Osteogenesis.

Science.gov (United States)

Zhang, Li; Zhou, Qing; Song, Wen; Wu, Kaimin; Zhang, Yumei; Zhao, Yimin

2017-10-11

Surface functionalization by small interfering RNA (siRNA) is a novel strategy for improved implant osseointegration. A gene delivery system with safety and high transfection activity is a crucial factor for an siRNA-functionalized implant to exert its biological function. To this end, polyethylene glycol (PEG) and polyethylenimine (PEI) dual-functionalized graphene oxide (GO; nGO-PEG-PEI) may present a promising siRNA vector. In this study, nanosized nGO-PEG-PEI was prepared and optimized for siRNA delivery. Titania nanotubes (NTs) fabricated by anodic oxidation were biomodified with nGO-PEG-PEI/siRNA by cathodic electrodeposition, designated as NT-GPP/siRNA. NT-GPP/siRNA possessed benign cytocompatibility, as evaluated by cell adhesion and proliferation. Cellular uptake and knockdown efficiency of the NT-GPP/siRNA were assessed by MC3T3-E1 cells, which exhibited high siRNA delivery efficiency and sustained target gene silencing. Casein kinase-2 interacting protein-1 (Ckip-1) is a negative regulator of bone formation. siRNA-targeting Ckip-1 (siCkip-1) was introduced to the implant, and a series of in vitro and in vivo experiments were carried out to evaluate the osteogenic capacity of NT-GPP/siCkip-1. NT-GPP/siCkip-1 dramatically improved the in vitro osteogenic differentiation of MC3T3-E1 cells in terms of improved osteogenesis-related gene expression, and increased alkaline phosphatase (ALP) production, collagen secretion, and extracellular matrix (ECM) mineralization. Moreover, NT-GPP/siCkip-1 led to apparently enhanced in vivo osseointegration, as indicated by histological staining and EDX line scanning. Collectively, these findings suggest that NT-GPP/siRNA represents a practicable and promising approach for implant functionalization, showing clinical potential for dental and orthopedic applications.

U-Mo/Al-Si interaction: Influence of Si concentration

International Nuclear Information System (INIS)

Allenou, J.; Palancher, H.; Iltis, X.; Cornen, M.; Tougait, O.; Tucoulou, R.; Welcomme, E.; Martin, Ph.; Valot, C.; Charollais, F.; Anselmet, M.C.; Lemoine, P.

2010-01-01

Within the framework of the development of low enriched nuclear fuels for research reactors, U-Mo/Al is the most promising option that has however to be optimised. Indeed at the U-Mo/Al interfaces between U-Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U-Mo/Al-Si protective layer around U-Mo particles appeared during fuel manufacturing. In this work, the evolution of the microstructure and composition of this protective layer with increasing Si concentrations in the Al matrix has been investigated. Conclusions are based on the characterization at the micrometer scale (X-ray diffraction and energy dispersive spectroscopy) of U-Mo7/Al-Si diffusion couples obtained by thermal annealing at 450 deg. C. Two types of interaction layers have been evidenced depending on the Si content in the Al-Si alloy: the threshold value is found at about 5 wt.% but obviously evolves with temperature. It has been shown that for Si concentrations ranging from 2 to 10 wt.%, the U-Mo7/Al-Si interaction is bi-layered and the Si-rich part is located close to the Al-Si for low Si concentrations (below 5 wt.%) and close to the U-Mo for higher Si concentrations. For Si weight fraction in the Al alloy lower than 5 wt.%, the Si-rich sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 , when the other sub-layer (close to U-Mo) is silicon free and made of UAl 3 and U 6 Mo 4 Al 43 . For Si weight concentrations above 5 wt.%, the Si-rich part becomes U 3 (Si, Al) 5 + U(Al, Si) 3 (close to U-Mo) and the other sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 . On the basis of these results and of a literature survey, a scheme is proposed to explain the formation of different types of ILs between U-Mo and Al-Si alloys (i.e. different protective layers).
Small interfering RNA targeted to stem-loop II of the 5' untranslated region effectively inhibits expression of six HCV genotypes

Directory of Open Access Journals (Sweden)

Dash Srikanta

2006-11-01

Full Text Available Abstract Background The antiviral action of interferon alpha targets the 5' untranslated region (UTR used by hepatitis C virus (HCV to translate protein by an internal ribosome entry site (IRES mechanism. Although this sequence is highly conserved among different clinical strains, approximately half of chronically infected hepatitis C patients do not respond to interferon therapy. Therefore, development of small interfering RNA (siRNA targeted to the 5'UTR to inhibit IRES mediated translation may represent an alternative approach that could circumvent the problem of interferon resistance. Results Four different plasmid constructs were prepared for intracellular delivery of siRNAs targeting the stem loop II-III of HCV 5' UTR. The effect of siRNA production on IRES mediated translation was investigated using chimeric clones between the gene for green fluorescence protein (GFP and IRES sequences of six different HCV genotypes. The siRNA targeted to stem loop II effectively mediated degradation of HCV IRES mRNA and inhibited GFP expression in the case of six different HCV genotypes, where as siRNAs targeted to stem loop III did not. Furthermore, intracytoplasmic expression of siRNA into transfected Huh-7 cells efficiently degraded HCV genomic RNA and inhibited core protein expression from infectious full-length infectious clones HCV 1a and HCV 1b strains. Conclusion These in vitro studies suggest that siRNA targeted to stem-loop II is highly effective inhibiting IRES mediated translation of the major genotypes of HCV. Stem-loop II siRNA may be a good target for developing an intracellular immunization strategy based antiviral therapy to inhibit hepatitis C virus strains that are not inhibited by interferon.
A ribonuclease coordinates siRNA amplification and mRNA cleavage during RNAi.

Science.gov (United States)

Tsai, Hsin-Yue; Chen, Chun-Chieh G; Conte, Darryl; Moresco, James J; Chaves, Daniel A; Mitani, Shohei; Yates, John R; Tsai, Ming-Daw; Mello, Craig C

2015-01-29

Effective silencing by RNA-interference (RNAi) depends on mechanisms that amplify and propagate the silencing signal. In some organisms, small-interfering RNAs (siRNAs) are amplified from target mRNAs by RNA-dependent RNA polymerase (RdRP). Both RdRP recruitment and mRNA silencing require Argonaute proteins, which are generally thought to degrade RNAi targets by directly cleaving them. However, in C. elegans, the enzymatic activity of the primary Argonaute, RDE-1, is not required for silencing activity. We show that RDE-1 can instead recruit an endoribonuclease, RDE-8, to target RNA. RDE-8 can cleave RNA in vitro and is needed for the production of 3' uridylated fragments of target mRNA in vivo. We also find that RDE-8 promotes RdRP activity, thereby ensuring amplification of siRNAs. Together, our findings suggest a model in which RDE-8 cleaves target mRNAs to mediate silencing, while generating 3' uridylated mRNA fragments to serve as templates for the RdRP-directed amplification of the silencing signal. Copyright © 2015 Elsevier Inc. All rights reserved.
Porous SiC/SiC composites development for industrial application

International Nuclear Information System (INIS)

Maeta, S.; Hinoki, T.

2014-01-01

Silicon carbide (SiC) is promising structural materials in nuclear fields due to an excellent irradiation resistance and low activation characteristics. Conventional SiC fibers reinforced SiC matrix (SiC/SiC composites) fabricated by liquid phase sintering (LPS-SiC/SiC composites) have been required high cost and long processing time. And microstructure and mechanical property data of finally obtained LPS-SiC/SiC composites are easily scattered, because quality of the composites depend on personal skill. Thus, conventional LPS-SiC/SiC composites are inadequate for industrial use. In order to overcome these issues, the novel “porous SiC/SiC composites” have been developed by means of liquid phase sintering fabrication process. The composites consist of porous SiC matrix and SiC fibers without conventional carbon interfacial layer. The composites don’t have concerns of the degradation interfacial layer at the severe accident. Porous SiC/SiC composites preform was prepared with a thin sheet shape of SiC, sintering additives and carbon powder mixture by tape casting process which was adopted because of productive and high yielding rate fabrication process. The preform was stacked with SiC fibers and sintered in hot-press at the high temperature in argon environment. The sintered preform was decarburized obtain porous matrix structure by heat-treatment in air. Moreover, mechanical property data scattering of the obtained porous SiC/SiC composites decreased. In the flexural test, the porous SiC/SiC composites showed pseudo-ductile behavior with sufficient strength even after heat treatment at high temperature in air. From these conclusions, it was proven that porous SiC/SiC composites were reliable material at severe environment such as high temperature in air, by introducing tape casting fabrication process that could produce reproducible materials with low cost and simple way. Therefore development of porous SiC/SiC composites for industrial application was
Heteroepitaxial Ge-on-Si by DC magnetron sputtering

Directory of Open Access Journals (Sweden)

Martin Steglich

2013-07-01

Full Text Available The growth of Ge on Si(100 by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380°C. Typical Stransky-Krastanov growth is observed at 410°C. At lower temperatures (320°C, films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed.
Systematic analysis of off-target effects in an RNAi screen reveals microRNAs affecting sensitivity to TRAIL-induced apoptosis

Directory of Open Access Journals (Sweden)

Enright Anton J

2010-03-01

Full Text Available Abstract Background RNA inhibition by siRNAs is a frequently used approach to identify genes required for specific biological processes. However RNAi screening using siRNAs is hampered by non-specific or off target effects of the siRNAs, making it difficult to separate genuine hits from false positives. It is thought that many of the off-target effects seen in RNAi experiments are due to siRNAs acting as microRNAs (miRNAs, causing a reduction in gene expression of unintended targets via matches to the 6 or 7 nt 'seed' sequence. We have conducted a careful examination of off-target effects during an siRNA screen for novel regulators of the TRAIL apoptosis induction pathway(s. Results We identified 3 hexamers and 3 heptamer seed sequences that appeared multiple times in the top twenty siRNAs in the TRAIL apoptosis screen. Using a novel statistical enrichment approach, we systematically identified a further 17 hexamer and 13 heptamer seed sequences enriched in high scoring siRNAs. The presence of one of these seeds sequences (which could explain 6 of 8 confirmed off-target effects is sufficient to elicit a phenotype. Three of these seed sequences appear in the human miRNAs miR-26a, miR-145 and miR-384. Transfection of mimics of these miRNAs protects several cell types from TRAIL-induced cell death. Conclusions We have demonstrated a role for miR-26a, miR-145 and miR-26a in TRAIL-induced apoptosis. Further these results show that RNAi screening enriches for siRNAs with relevant off-target effects. Some of these effects can be identified by the over-representation of certain seed sequences in high-scoring siRNAs and we demonstrate the usefulness of such systematic analysis of enriched seed sequences.
Theranostics Targeting Metastatic Breast Cancer

Science.gov (United States)

2016-10-01

Knapp DW. Targeting folate receptors to treat invasive urinary bladder cancer . Cancer Res 2013;73(2):875–884. 71. Holm J, Hansen SI, Hoier-Madsen M...purpose of this review, active targeting in cancer research encompasses strategies wherein a ligand for a cell surface receptor expressed on tumor...trafficking, thus impacting the efficacy of receptor -mediated drug delivery for cancer therapy. These factors include the following: (i) the rate of ligand
Biomorphous SiSiC/Al-Si ceramic composites manufactured by squeeze casting: microstructure and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Zollfrank, C.; Travitzky, N.; Sieber, H.; Greil, P. [Department of Materials Science, Glass and Ceramics, University of Erlangen-Nuernberg (Germany); Selchert, T. [Advanced Ceramics Group, Technical University of Hamburg-Harburg (Germany)

2005-08-01

SiSiC/Al-Si composites were fabricated by pressure-assisted infiltration of an Al-Si alloy into porous biocarbon preforms derived from the rattan palm. Al-Si alloy was found in the pore channels of the biomorphous SiSiC preform, whereas SiC and carbon were present in the struts. The formation of a detrimental Al{sub 4}C{sub 3}-phase was not observed in the composites. A bending strength of 200 MPa was measured. The fractured surfaces showed pull-out of the Al-alloy. (Abstract Copyright [2005], Wiley Periodicals, Inc.)
Reaction mechanisms at 4H-SiC/SiO2 interface during wet SiC oxidation

Science.gov (United States)

Akiyama, Toru; Hori, Shinsuke; Nakamura, Kohji; Ito, Tomonori; Kageshima, Hiroyuki; Uematsu, Masashi; Shiraishi, Kenji

2018-04-01

The reaction processes at the interface between SiC with 4H structure (4H-SiC) and SiO2 during wet oxidation are investigated by electronic structure calculations within the density functional theory. Our calculations for 4H-SiC/SiO2 interfaces with various orientations demonstrate characteristic features of the reaction depending on the crystal orientation of SiC: On the Si-face, the H2O molecule is stable in SiO2 and hardly reacts with the SiC substrate, while the O atom of H2O can form Si-O bonds at the C-face interface. Two OH groups are found to be at least necessary for forming new Si-O bonds at the Si-face interface, indicating that the oxidation rate on the Si-face is very low compared with that on the C-face. On the other hand, both the H2O molecule and the OH group are incorporated into the C-face interface, and the energy barrier for OH is similar to that for H2O. By comparing the calculated energy barriers for these reactants with the activation energies of oxide growth rate, we suggest the orientation-dependent rate-limiting processes during wet SiC oxidation.
Fusion barrier distributions in 28,30Si + 124Sn reactions

International Nuclear Information System (INIS)

Danu, L.S.; Nayak, B.K.; Biswas, D.C.; Saxena, A.; Thomas, R.G.; Mirgule, E.T.; Choudhury, R.K.

2009-01-01

The coupling of various degrees of freedom such as static deformation, inelastic excitation and nucleon transfer with the relative motion gives rise to a distribution of barrier in heavy ion induced fusion reactions. The barrier distribution is a fingerprint of the reaction characterizing the important channel couplings. The relative importance of various couplings in fusion reaction is of topical interest. In an earlier study with deformed projectiles 28,30 Si on 115 In target, it was observed that the barrier distributions get affected due to coulomb reorientation of the deformed projectile nuclei in the field of target nucleus thus giving rise to fusion hindrance at sub-barrier energies. In that study, we considered deformed projectile rotational and positive Q-value transfer channel couplings to relative motion in fusion for investigation of Coulomb reorientation and no inelastic coupling of the 115 In target was considered. In the present work, we have extended the measurements with 124 Sn target and inelastic coupling of target has been considered in the coupled channel calculations. The fusion barrier distributions for 28,30 Si + 124 Sn systems have been obtained by quasi-elastic scattering measurements at backward angles and the results compared with the predictions of coupled channel calculations
Total Ionizing Dose Effects of Si Vertical Diffused MOSFET with SiO2 and Si3N4/SiO2 Gate Dielectrics

Directory of Open Access Journals (Sweden)

Jiongjiong Mo

2017-01-01

Full Text Available The total ionizing dose irradiation effects are investigated in Si vertical diffused MOSFETs (VDMOSs with different gate dielectrics including single SiO2 layer and double Si3N4/SiO2 layer. Radiation-induced holes trapping is greater for single SiO2 layer than for double Si3N4/SiO2 layer. Dielectric oxidation temperature dependent TID effects are also studied. Holes trapping induced negative threshold voltage shift is smaller for SiO2 at lower oxidation temperature. Gate bias during irradiation leads to different VTH shift for different gate dielectrics. Single SiO2 layer shows the worst negative VTH at VG=0 V, while double Si3N4/SiO2 shows negative VTH shift at VG=-5 V, positive VTH shift at VG=10 V, and negligible VTH shift at VG=0 V.
Fabrication of multilayered Ge nanocrystals embedded in SiOxGeNy films

International Nuclear Information System (INIS)

Gao Fei; Green, Martin A.; Conibeer, Gavin; Cho, Eun-Chel; Huang Yidan; Perez-Wurfl, Ivan; Flynn, Chris

2008-01-01

Multilayered Ge nanocrystals embedded in SiO x GeN y films have been fabricated on Si substrate by a (Ge + SiO 2 )/SiO x GeN y superlattice approach, using a rf magnetron sputtering technique with a Ge + SiO 2 composite target and subsequent thermal annealing in N 2 ambient at 750 deg. C for 30 min. X-ray diffraction (XRD) measurement indicated the formation of Ge nanocrystals with an average size estimated to be 5.4 nm. Raman scattering spectra showed a peak of the Ge-Ge vibrational mode downward shifted to 299.4 cm -1 , which was caused by quantum confinement of phonons in the Ge nanocrystals. Transmission electron microscopy (TEM) revealed that Ge nanocrystals were confined in (Ge + SiO 2 ) layers. This superlattice approach significantly improved both the size uniformity of Ge nanocrystals and their uniformity of spacing on the 'Z' growth direction
Inhibition of Hepatitis C Virus in Mice by a Small Interfering RNA Targeting a Highly Conserved Sequence in Viral IRES Pseudoknot.

Directory of Open Access Journals (Sweden)

Jae-Su Moon

Full Text Available The hepatitis C virus (HCV internal ribosome entry site (IRES that directs cap-independent viral translation is a primary target for small interfering RNA (siRNA-based HCV antiviral therapy. However, identification of potent siRNAs against HCV IRES by bioinformatics-based siRNA design is a challenging task given the complexity of HCV IRES secondary and tertiary structures and association with multiple proteins, which can also dynamically change the structure of this cis-acting RNA element. In this work, we utilized siRNA tiling approach whereby siRNAs were tiled with overlapping sequences that were shifted by one or two nucleotides over the HCV IRES stem-loop structures III and IV spanning nucleotides (nts 277-343. Based on their antiviral activity, we mapped a druggable region (nts 313-343 where the targets of potent siRNAs were enriched. siIE22, which showed the greatest anti-HCV potency, targeted a highly conserved sequence across diverse HCV genotypes, locating within the IRES subdomain IIIf involved in pseudoknot formation. Stepwise target shifting toward the 5' or 3' direction by 1 or 2 nucleotides reduced the antiviral potency of siIE22, demonstrating the importance of siRNA accessibility to this highly structured and sequence-conserved region of HCV IRES for RNA interference. Nanoparticle-mediated systemic delivery of the stability-improved siIE22 derivative gs_PS1 siIE22, which contains a single phosphorothioate linkage on the guide strand, reduced the serum HCV genome titer by more than 4 log10 in a xenograft mouse model for HCV replication without generation of resistant variants. Our results provide a strategy for identifying potent siRNA species against a highly structured RNA target and offer a potential pan-HCV genotypic siRNA therapy that might be beneficial for patients resistant to current treatment regimens.
Nanocatalytic growth of Si nanowires from Ni silicate coated SiC nanoparticles on Si solar cell.

Science.gov (United States)

Parida, Bhaskar; Choi, Jaeho; Ji, Hyung Yong; Park, Seungil; Lim, Gyoungho; Kim, Keunjoo

2013-09-01

We investigated the nanocatalytic growth of Si nanowires on the microtextured surface of crystalline Si solar cell. 3C-SiC nanoparticles have been used as the base for formation of Ni silicate layer in a catalytic reaction with the Si melt under H2 atmosphere at an annealing temperature of 1100 degrees C. The 10-nm thick Ni film was deposited after the SiC nanoparticles were coated on the microtextured surface of the Si solar cell by electron-beam evaporation. SiC nanoparticles form a eutectic alloy surface of Ni silicate and provide the base for Si supersaturation as well as the Ni-Si alloy layer on Si substrate surface. This bottom reaction mode for the solid-liquid-solid growth mechanism using a SiC nanoparticle base provides more stable growth of nanowires than the top reaction mode growth mechanism in the absence of SiC nanoparticles. Thermally excited Ni nanoparticle forms the eutectic alloy and provides collectively excited electrons at the alloy surface, which reduces the activation energy of the nanocatalytic reaction for formation of nanowires.
Perivascular delivery of Notch 1 siRNA inhibits injury-induced arterial remodeling.

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Eileen M Redmond

Full Text Available To determine the efficacy of perivascular delivery of Notch 1 siRNA in preventing injury-induced arterial remodeling.Carotid artery ligation was performed to induce arterial remodeling. After 14 days, morphometric analysis confirmed increased vSMC growth and subsequent media thickening and neointimal formation. Laser capture microdissection, quantitative qRT-PCR and immunoblot analysis of medial tissue revealed a significant increase in Notch1 receptor and notch target gene, Hrt 1 and 2 expression in the injured vessels. Perivascular delivery of Notch 1 siRNA by pluronic gel inhibited the injury-induced increase in Notch 1 receptor and target gene expression when compared to scrambled siRNA controls while concomitantly reducing media thickening and neointimal formation to pre-injury, sham-operated levels. Selective Notch 1 knockdown also reversed the injury-induced inhibition of pro-apoptotic Bax expression while decreasing injury-induced anti-apoptotic Bcl-XL expression to sham-operated control levels. In parallel experiments, proliferative cyclin levels, as measured by PCNA expression, were reversed to sham-operated control levels following selective Notch 1 knockdown.These results suggest that injury-induced arterial remodeling can be successfully inhibited by localized perivascular delivery of Notch 1 siRNA.
Oxide Structure Dependence of SiO2/SiOx/3C-SiC/n-Type Si Nonvolatile Resistive Memory on Memory Operation Characteristics

Science.gov (United States)

Yamaguchi, Yuichiro; Shouji, Masatsugu; Suda, Yoshiyuki

2012-11-01

We have investigated the dependence of the oxide layer structure of our previously proposed metal/SiO2/SiOx/3C-SiC/n-Si/metal metal-insulator-semiconductor (MIS) resistive memory device on the memory operation characteristics. The current-voltage (I-V) measurement and X-ray photoemission spectroscopy results suggest that SiOx defect states mainly caused by the oxidation of 3C-SiC at temperatures below 1000 °C are related to the hysteresis memory behavior in the I-V curve. By restricting the SiOx interface region, the number of switching cycles and the on/off current ratio are more enhanced. Compared with a memory device formed by one-step or two-step oxidation of 3C-SiC, a memory device formed by one-step oxidation of Si/3C-SiC exhibits a more restrictive SiOx interface with a more definitive SiO2 layer and higher memory performances for both the endurance switching cycle and on/off current ratio.
Combination siRNA therapy against feline coronavirus can delay the emergence of antiviral resistance in vitro.

Science.gov (United States)

McDonagh, Phillip; Sheehy, Paul A; Norris, Jacqueline M

2015-03-23

Virulent biotypes of feline coronavirus (FCoV), commonly referred to as feline infectious peritonitis virus (FIPV), can result in the development of feline infectious peritonitis (FIP), a typically fatal immune mediated disease for which there is currently no effective antiviral treatment. We previously reported the successful in vitro inhibition of FIPV replication by synthetic siRNA mediated RNA interference (RNAi) in an immortalised cell line (McDonagh et al., 2011). A major challenge facing the development of any antiviral strategy is that of resistance, a problem which is particularly acute for RNAi based therapeutics due to the exquisite sequence specificity of the targeting mechanism. The development of resistance during treatment can be minimised using combination therapy to raise the genetic barrier or using highly potent compounds which result in a more rapid and pronounced reduction in the viral replication rate, thereby reducing the formation of mutant, and potentially resistant viruses. This study investigated the efficacy of combination siRNA therapy and its ability to delay or prevent viral escape. Virus serially passaged through cells treated with a single or dual siRNAs rapidly acquired resistance, with mutations identified in the siRNA target sites. Combination therapy with three siRNA prevented viral escape over the course of five passages. To identify more potent silencing molecules we also compared the efficacy, in terms of potency and duration of action, of canonical versus Dicer-substrate siRNAs for two previously identified effective viral motifs. Dicer-substrate siRNAs showed equivalent or better potency than canonical siRNAs for the target sites investigated, and may be a more appropriate molecule for in vivo use. Combined, these data inform the potential therapeutic application of antiviral RNAi against FIPV. Copyright © 2014 Elsevier B.V. All rights reserved.
DISE: A Seed-Dependent RNAi Off-Target Effect That Kills Cancer Cells.

Science.gov (United States)

Putzbach, William; Gao, Quan Q; Patel, Monal; Haluck-Kangas, Ashley; Murmann, Andrea E; Peter, Marcus E

2018-01-01

Off-target effects (OTEs) represent a significant caveat for RNAi caused by substantial complementarity between siRNAs and unintended mRNAs. We now discuss the existence of three types of seed-dependent OTEs (sOTEs). Type I involves unintended targeting through the guide strand seed of an siRNA. Type II is caused by the activity of the seed on the designated siRNA passenger strand when loaded into the RNA-induced silencing complex (RISC). Both type I and II sOTEs will elicit unpredictable cellular responses. By contrast, in sOTE type III the guide strand seed preferentially targets essential survival genes resulting in death induced by survival gene elimination (DISE). In this Opinion article, we discuss DISE as a consequence of RNAi that may preferentially affect cancer cells. Copyright © 2017 Elsevier Inc. All rights reserved.
Interfacial characterization of CVI-SiC/SiC composites

International Nuclear Information System (INIS)

Yang, W.; Kohyama, A.; Noda, T.; Katoh, Y.; Hinoki, T.; Araki, H.; Yu, J.

2002-01-01

The mechanical properties of the interfaces of two families of chemical vapor infiltration SiC/SiC composites, advanced Tyranno-SA and Hi-Nicalon fibers reinforced SiC/SiC composites with various carbon and SiC/C interlayers, were investigated by single fiber push-out/push-back tests. Interfacial debonding and fibers sliding mainly occurred adjacent to the first carbon layer on the fibers. The interfacial debonding strengths and frictional stresses for both Tyranno-SA/SiC and Hi-Nicalon/SiC composites were correlated with the first carbon layer thickness. Tyranno-SA/SiC composites exhibited much larger interfacial frictional stresses compared to Hi-Nicalon/SiC composites. This was assumed to be mainly contributed by the rather rough surface of the Tyranno-SA fiber
Research on a Micro-Nano Si/SiGe/Si Double Heterojunction Electro-Optic Modulation Structure

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Song Feng

2018-01-01

Full Text Available The electro-optic modulator is a very important device in silicon photonics, which is responsible for the conversion of optical signals and electrical signals. For the electro-optic modulator, the carrier density of waveguide region is one of the key parameters. The traditional method of increasing carrier density is to increase the external modulation voltage, but this way will increase the modulation loss and also is not conducive to photonics integration. This paper presents a micro-nano Si/SiGe/Si double heterojunction electro-optic modulation structure. Based on the band theory of single heterojunction, the barrier heights are quantitatively calculated, and the carrier concentrations of heterojunction barrier are analyzed. The band and carrier injection characteristics of the double heterostructure structure are simulated, respectively, and the correctness of the theoretical analysis is demonstrated. The micro-nano Si/SiGe/Si double heterojunction electro-optic modulation is designed and tested, and comparison of testing results between the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation and the micro-nano Silicon-On-Insulator (SOI micro-ring electro-optic modulation, Free Spectrum Range, 3 dB Bandwidth, Q value, extinction ratio, and other parameters of the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation are better than others, and the modulation voltage and the modulation loss are lower.

Dose-ranging evaluation of intravitreal siRNA PF-04523655 for diabetic macular edema (the DEGAS study)

DEFF Research Database (Denmark)

Nguyen, Quan Dong; Schachar, Ronald A; Nduaka, Chudy I

2012-01-01

To evaluate the safety and efficacy of three doses of PF-04523655, a 19-nucleotide methylated double stranded siRNA targeting the RTP801 gene, for the treatment of diabetic macular edema (DME) compared to focal/grid laser photocoagulation.......To evaluate the safety and efficacy of three doses of PF-04523655, a 19-nucleotide methylated double stranded siRNA targeting the RTP801 gene, for the treatment of diabetic macular edema (DME) compared to focal/grid laser photocoagulation....
Smart Inulin-Based Polycationic Nanodevices for siRNA Delivery.

Science.gov (United States)

Cavallaro, G; Sardo, C; Scialabba, C; Licciardi, M; Giammona, G

2017-01-01

The advances of short interfering RNA (siRNA) mediated therapy provide a powerful option for the treatment of many diseases by silencing the expression of targeted genes including cancer development and progression. Inulin is a very simple and biocompatible polysaccharide proposed by our groups to produce interesting delivery systems for Nucleic Acid Based Drugs (NABDs), such as siRNA, either as polycations able to give polyplexes and polymeric coatings for nanosystems having a metallic core. In this research field, different functionalizing groups were linked to the inulin backbone with specific aims including oligoamine such as Ethylendiammine (EDA), Diethylediamine (DETA), Spermine, (SPM) etc. In this contribution the main Inulin-based nanodevices for the delivery of siRNA have been reported, analysed and compared with particular reference to their chemical design and structure, biocompatibility, siRNA complexing ability, silencing ability. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
Low dose irradiation performance of SiC interphase SiC/SiC composites

International Nuclear Information System (INIS)

Snead, L.L.; Lowden, R.A.; Strizak, J.; More, K.L.; Eatherly, W.S.; Bailey, J.; Williams, A.M.; Osborne, M.C.; Shinavski, R.J.

1998-01-01

Reduced oxygen Hi-Nicalon fiber reinforced composite SiC materials were densified with a chemically vapor infiltrated (CVI) silicon carbide (SiC) matrix and interphases of either 'porous' SiC or multilayer SiC and irradiated to a neutron fluence of 1.1 x 10 25 n m -2 (E>0.1 MeV) in the temperature range of 260 to 1060 C. The unirradiated properties of these composites are superior to previously studied ceramic grade Nicalon fiber reinforced/carbon interphase materials. Negligible reduction in the macroscopic matrix microcracking stress was observed after irradiation for the multilayer SiC interphase material and a slight reduction in matrix microcracking stress was observed for the composite with porous SiC interphase. The reduction in strength for the porous SiC interfacial material is greatest for the highest irradiation temperature. The ultimate fracture stress (in four point bending) following irradiation for the multilayer SiC and porous SiC interphase materials was reduced by 15% and 30%, respectively, which is an improvement over the 40% reduction suffered by irradiated ceramic grade Nicalon fiber materials fabricated in a similar fashion, though with a carbon interphase. The degradation of the mechanical properties of these composites is analyzed by comparison with the irradiation behavior of bare Hi-Nicalon fiber and Morton chemically vapor deposited (CVD) SiC. It is concluded that the degradation of these composites, as with the previous generation ceramic grade Nicalon fiber materials, is dominated by interfacial effects, though the overall degradation of fiber and hence composite is reduced for the newer low-oxygen fiber. (orig.)
Targeted NGF siRNA delivery attenuates sympathetic nerve sprouting and deteriorates cardiac dysfunction in rats with myocardial infarction.

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Hesheng Hu

Full Text Available Nerve growth factor (NGF is involved in nerve sprouting, hyper-innervation, angiogenesis, anti-apoptosis, and preservation of cardiac function after myocardial infarction (MI. Positively modulating NGF expression may represent a novel pharmacological strategy to improve post-infarction prognosis. In this study, lentivirus encoding NGF short interfering RNA (siRNA was prepared, and MI was modeled in the rat using left anterior descending coronary artery ligation. Rats were randomly grouped to receive intramyocardial injection of lentiviral solution containing NGF-siRNA (n = 19, MI-SiNGF group, lentiviral solution containing empty vector (n = 18, MI-GFP group or 0.9% NaCl solution (n = 18, MI-control group, or to receive thoracotomy and pericardiotomy (n = 17, sham-operated group. At 1, 2, 4, and 8 wk after transduction, rats in the MI-control group had higher levels of NGF mRNA and protein than those in the sham-operated group, rats in the MI-GFP group showed similar levels as the MI-control group, and rats in the MI-SiNGF group had lower levels compared to the MI-GFP group, indicating that MI model was successfully established and NGF siRNA effectively inhibited the expression of NGF. At 8 wk, echocardiographic and hemodynamic studies revealed a more severe cardiac dysfunction in the MI-siRNA group compared to the MI-GFP group. Moreover, rats in the MI-siRNA group had lower mRNA and protein expression levels of tyrosine hydroxylase (TH and growth-associated protein 43-positive nerve fibers (GAP-43 at both the infarcted border and within the non-infarcted left ventricles (LV. NGF silencing also reduced the vascular endothelial growth factor (VEGF expression and decreased the arteriolar and capillary densities at the infarcted border compared to the MI-GFP group. Histological analysis indicated a large infarcted size in the MI-SiNGF group. These findings suggested that endogenous NGF silencing attenuated sympathetic nerve sprouting
ToF-MEIS stopping measurements in thin SiC films

International Nuclear Information System (INIS)

Linnarsson, M.K.; Khartsev, S.; Primetzhofer, D.; Possnert, G.; Hallén, A.

2014-01-01

Electronic stopping in thin, amorphous, SiC films has been studied by time-of-flight medium energy ion scattering and conventional Rutherford backscattering spectrometry. Amorphous SiC films (8, 21 and 36 nm) were prepared by laser ablation using a single crystalline silicon carbide target. Two kinds of substrate films, one with a lower atomic mass (carbon) and one with higher atomic mass (iridium) compared to silicon has been used. Monte Carlo simulations have been used to evaluate electronic stopping from the shift in energy for the signal scattered from Ir with and without SiC. The two kinds of samples are used to illustrate the strength and challenges for ToF-MEIS compared to conventional RBS
Carbon redistribution and precipitation in high temperature ion-implanted strained Si/SiGe/Si multi-layered structures

DEFF Research Database (Denmark)

Gaiduk, Peter; Hansen, John Lundsgaard; Nylandsted Larsen, Arne

2014-01-01

Graphical abstract Carbon depth profiles after high temperature implantation in strained Si/SiGe/Si multilayered system and induced structural defects.......Graphical abstract Carbon depth profiles after high temperature implantation in strained Si/SiGe/Si multilayered system and induced structural defects....
Study on density distribution and diffusion of deuterons in mono- and polycrystalline Ni absorbers using the nuclear reaction method

International Nuclear Information System (INIS)

Heintze, V.

1976-01-01

Irradiation experiments with cooled poly- and monocrystalline Ni absorbers are reported on. A very complex irradiation apparatus was set up, and a nuclear physics method was tested which enables an alignment of low-index crystal directions of monocrystalline absorbers in the target chamber with an exactness of at least 0.1 0 with regard to the ion beam. The nuclear reaction technique for the D(d,p)T reaction was developed far enough to enable a non-destructive determination of deuteron density distributions by analyzing proton spectra of this reaction. At low incorporation doses, there was no dose dependence of density distributions in monocrystalline Ni samples. Profile changes interpreted by a 'blurring' of the incident angle α due to an arching of the surface were only observed at doses Qsub(w) approximately > 3 x 10 18 deuterons/cm 2 . Furthermore, in polycrystalline Ni absorbers, there was a dependence of deuteron distributions on the angle between the beam and the absorber surface, which may be interpreted as a picture of a certain deposition, probability of single ions. In monocrystalline absorbers, range distributions for each of the low-index crystal directions were measured and compared with similar profiles of the polycrystalline absorber which had been measured at the same incident angle α. (orig.) [de
High-dose MeV electron irradiation of Si-SiO2 structures implanted with high doses Si+

Science.gov (United States)

Kaschieva, S.; Angelov, Ch; Dmitriev, S. N.

2018-03-01

The influence was studied of 22-MeV electron irradiation on Si-SiO2 structures implanted with high-fluence Si+ ions. Our earlier works demonstrated that Si redistribution is observed in Si+-ion-implanted Si-SiO2 structures (after MeV electron irradiation) only in the case when ion implantation is carried out with a higher fluence (1016 cm-2). We focused our attention on the interaction of high-dose MeV electron irradiation (6.0×1016 cm-2) with n-Si-SiO2 structures implanted with Si+ ions (fluence 5.4×1016 cm-2 of the same order magnitude). The redistribution of both oxygen and silicon atoms in the implanted Si-SiO2 samples after MeV electron irradiation was studied by Rutherford back-scattering (RBS) spectroscopy in combination with a channeling technique (RBS/C). Our results demonstrated that the redistribution of oxygen and silicon atoms in the implanted samples reaches saturation after these high doses of MeV electron irradiation. The transformation of amorphous SiO2 surface into crystalline Si nanostructures (after MeV electron irradiation) was evidenced by atomic force microscopy (AFM). Silicon nanocrystals are formed on the SiO2 surface after MeV electron irradiation. The shape and number of the Si nanocrystals on the SiO2 surface depend on the MeV electron irradiation, while their size increases with the dose. The mean Si nanocrystals height is 16-20 nm after irradiation with MeV electrons at the dose of 6.0×1016 cm-2.
Applications of Si/SiGe heterostructures to CMOS devices

International Nuclear Information System (INIS)

Sidek, R.M.

1999-03-01

For more than two decades, advances in MOSFETs used in CMOS VLSI applications have been made through scaling to ever smaller dimensions for higher packing density, faster circuit speed and lower power dissipation. As scaling now approaches nanometer regime, the challenge for further scaling becomes greater in terms of technology as well as device reliability. This work presents an alternative approach whereby non-selectively grown Si/SiGe heterostructure system is used to improve device performance or to relax the technological challenge. SiGe is considered to be of great potential because of its promising properties and its compatibility with Si, the present mainstream material in microelectronics. The advantages of introducing strained SiGe in CMOS technology are examined through two types of device structure. A novel structure has been fabricated in which strained SiGe is incorporated in the source/drain of P-MOSFETs. Several advantages of the Si/SiGe source/drain P-MOSFETs over Si devices are experimentally, demonstrated for the first time. These include reduction in off-state leakage and punchthrough susceptibility, degradation of parasitic bipolar transistor (PBT) action, suppression of CMOS latchup and suppression of PBT-induced breakdown. The improvements due to the Si/SiGe heterojunction are supported by numerical simulations. The second device structure makes use of Si/SiGe heterostructure as a buried channel to enhance the hole mobility of P-MOSFETs. The increase in the hole mobility will benefit the circuit speed and device packing density. Novel fabrication processes have been developed to integrate non-selective Si/SiGe MBE layers into self-aligned PMOS and CMOS processes based on Si substrate. Low temperature processes have been employed including the use of low-pressure chemical vapor deposition oxide and plasma anodic oxide. Low field mobilities, μ 0 are extracted from the transfer characteristics, Id-Vg of SiGe channel P-MOSFETs with various Ge
Strategies for Improving siRNA-Induced Gene Silencing Efficiency.

Science.gov (United States)

Safari, Fatemeh; Rahmani Barouji, Solmaz; Tamaddon, Ali Mohammad

2017-12-01

Purpose: Human telomerase reverse transcriptase (hTERT) plays a crucial role in tumorigenesis and progression of cancers. Gene silencing of hTERT by short interfering RNA (siRNA) is considered as a promising strategy for cancer gene therapy. Various algorithms have been devised for designing a high efficient siRNA which is a significant issue in the clinical usage. Thereby, in the present study, the relation of siRNA designing criteria and the gene silencing efficiency was evaluated. Methods: The siRNA sequences were designed and characterized by using on line soft wares. Cationic co-polymer (polyethylene glycol-g-polyethylene imine (PEG-g-PEI)) was used for the construction of polyelectrolyte complexes (PECs) containing siRNAs. The cellular uptake of the PECs was evaluated. The gene silencing efficiency of different siRNA sequences was investigated and the effect of observing the rational designing on the functionality of siRNAs was assessed. Results: The size of PEG-g-PEI siRNA with N/P (Nitrogen/Phosphate) ratio of 2.5 was 114 ± 0.645 nm. The transfection efficiency of PECs was desirable (95.5% ± 2.4%.). The results of Real-Time PCR showed that main sequence (MS) reduced the hTERT expression up to 90% and control positive sequence (CPS) up to 63%. These findings demonstrated that the accessibility to the target site has priority than the other criteria such as sequence preferences and thermodynamic features. Conclusion: siRNA opens a hopeful window in cancer therapy which provides a convenient and tolerable therapeutic approach. Thereby, using the set of criteria and rational algorithms in the designing of siRNA remarkably affect the gene silencing efficiency.
Proton production from Si+Au collisions at 14.5 A/center dot/GeV

International Nuclear Information System (INIS)

Sarabura, M.; Abbott, T.; Akiba, Y.

1988-01-01

Recent results are presented from the study of central Si+Au → p+X, Si+Au → π/sup +-/+X, and Si+Cu → p+X at 14.5 A/center dot/GeV. The distribution of protons in rapidity indicates that many target protons are found above 0.5 units. The variation of the slope parameter in rapidity is consistent with a thermal source of protons at the geometric center-of-mass rapidity. 4 refs., 4 figs
CD147-targeting siRNA inhibits cell-matrix adhesion of human malignant melanoma cells by phosphorylating focal adhesion kinase.

Science.gov (United States)

Nishibaba, Rie; Higashi, Yuko; Su, Juan; Furukawa, Tatsuhiko; Kawai, Kazuhiro; Kanekura, Takuro

2012-01-01

CD147/basigin, highly expressed on the surface of malignant tumor cells including malignant melanoma (MM) cells, plays a critical role in the invasiveness and metastasis of MM. Metastasis is an orchestrated process comprised of multiple steps including adhesion and invasion. Integrin, a major adhesion molecule, co-localizes with CD147/basigin on the cell surface. Using the human MM cell line A375 that highly expresses CD147/basigin, we investigated whether CD147/basigin is involved in adhesion in association with integrin. CD147/basigin was knocked-down using siRNA targeting CD147 to elucidate the role of CD147/basigin. Cell adhesion was evaluated by adhesion assay on matrix-coated plates. The localization of integrin was inspected under a confocal microscope and the expression and phosphorylation of focal adhesion kinase (FAK), a downstream kinase of integrin, were examined by western blot analysis. Silencing of CD147/basigin in A375 cells by siRNA induced the phosphorylation of FAK at Y397. Integrin identified on the surface of parental cells was distributed in a speckled fashion in the cytoplasm of CD147 knockdown cells, resulting in morphological changes from a round to a polygonal shape with pseudopodial protrusions. Silencing of CD147/basigin in A375 cells clearly weakened their adhesiveness to collagen I and IV. Our results suggest that CD147/basigin regulates the adhesion of MM cells to extracellular matrices and of integrin β1 signaling via the phosphorylation of FAK. © 2011 Japanese Dermatological Association.
Site-Specific Modification Using the 2′-Methoxyethyl Group Improves the Specificity and Activity of siRNAs

Directory of Open Access Journals (Sweden)

Xinyun Song

2017-12-01

Full Text Available Rapid progress has been made toward small interfering RNA (siRNA-based therapy for human disorders, but rationally optimizing siRNAs for high specificity and potent silencing remains a challenge. In this study, we explored the effect of chemical modification at the cleavage site of siRNAs. We found that modifications at positions 9 and 10 markedly reduced the silencing potency of the unmodified strand of siRNAs but were well tolerated by the modified strand. Intriguingly, addition of the 2′-methoxyethyl (MOE group at the cleavage site improved both the specificity and silencing activity of siRNAs by facilitating the oriented RNA-induced silencing complex (RISC loading of the modified strand. Furthermore, we combined MOE modifications at positions 9 and 10 of one strand together with 2′-O-methylation (OMe at position 14 of the other strand and found a synergistic effect that improved the specificity of siRNAs. The surprisingly beneficial effect of the combined modification was validated using siRNA-targeting endogenous gene intercellular adhesion molecule 1 (ICAM1. We found that the combined modifications eliminated its off-target effects. In conclusion, we established effective strategies to optimize siRNAs using site-specific MOE modifications. The findings may allow the creation of superior siRNAs for therapy in terms of activity and specificity.
EDM machinability of SiCw/Al composites

Science.gov (United States)

Ramulu, M.; Taya, M.

1989-01-01

Machinability of high temperature composites was investigated. Target materials, 15 and 25 vol pct SiC whisker-2124 aluminum composites, were machined by electrodischarge sinker machining and diamond saw. The machined surfaces of these metal matrix composites were examined by SEM and profilometry to determine the surface finish. Microhardness measurements were also performed on the as-machined composites.
Local administration of siRNA through Microneedle: Optimization, Bio-distribution, Tumor Suppression and Toxicity

Science.gov (United States)

Tang, Tao; Deng, Yan; Chen, Jiao; Zhao, Yi; Yue, Ruifeng; Choy, Kwong Wai; Wang, Chi Chiu; Du, Quan; Xu, Yan; Han, Linxiao; Chung, Tony Kwok Hung

2016-07-01

Although RNA interference may become a novel therapeutic approach for cancer treatment, target-site accumulation of siRNA to achieve therapeutic dosage will be a major problem. Microneedle represents a better way to deliver siRNAs and we have evaluated for the first time the capability of a silicon microneedle array for delivery of Gapdh siRNA to the skin in vivo and the results showed that the microneedle arrays could effectively deliver siRNA to relevant regions of the skin noninvasively. For the further study in this field, we evaluated the efficacy of the injectable microneedle device for local delivery of siRNA to the mouse xenograft. The results presented here indicate that local administration of siRNA through injectable microneedle could effectively deliver siRNA into the tumor region, and inhibit tumor progression without major adverse effects.
Irradiation effect on Nite-SiC/SiC composites

International Nuclear Information System (INIS)

Hinoki, T.; Choi, Y.B.; Kohyama, A.; Ozawa, K.

2007-01-01

Full text of publication follows: Silicon carbide (SiC) and SiC composites are significantly attractive materials for nuclear application in particular due to exceptional low radioactivity, excellent high temperature mechanical properties and chemical stability. Despite of the excellent potential of SiC/SiC composites, the prospect of industrialization has not been clear mainly due to the low productivity and the high material cost. Chemical vapor infiltration (CVI) method can produce the excellent SiC/SiC composites with highly crystalline and excellent mechanical properties. It has been reported that the high purity SiC/SiC composites reinforced with highly crystalline fibers and fabricated by CVI method is very stable to neutron irradiation. However the production cost is high and it is difficult to fabricate thick and dense composites by CVI method. The novel processing called Nano-powder Infiltration and Transient Eutectic Phase (NITE) Processing has been developed based on the liquid phase sintering (LPS) process modification. The NITE processing can achieve both the excellent material quality and the low processing cost. The productivity of the processing is also excellent, and various kinds of shape and size of SiC/SiC composites can be produced by the NITE processing. The NITE processing can form highly crystalline matrix, which is requirement for nuclear application. The objective of this work is to understand irradiation effect of the NITESiC/SiC composites. The SiC/SiC composites used were reinforced with high purity SiC fibers, Tyranno TM SA and fabricated by the NITE method. The NITE-SiC/SiC composite bars and reference monolithic SiC bars fabricated by CVI and NITE were irradiated at up to 1.0 dpa and 600-1000 deg. C at JMTR, Japan. Mechanical properties of non-irradiated and irradiated NITESiC/ SiC composites bars were evaluated by tensile tests. Monolithic SiC bars were evaluated by flexural tests. The fracture surface was examined by SEM. Ultimate
2’f-OMe-phosphorodithioate modified siRNAs show increased loading into the RISC complex and enhanced anti-tumour activity

Science.gov (United States)

Wu, Sherry Y.; Yang, Xianbin; Gharpure, Kshipra M.; Hatakeyama, Hiroto; Egli, Martin; McGuire, Michael H.; Nagaraja, Archana S.; Miyake, Takahito M.; Rupaimoole, Rajesha; Pecot, Chad V.; Taylor, Morgan; Pradeep, Sunila; Sierant, Malgorzata; Rodriguez-Aguayo, Cristian; Choi, Hyun J.; Previs, Rebecca A.; Armaiz-Pena, Guillermo N.; Huang, Li; Martinez, Carlos; Hassell, Tom; Ivan, Cristina; Sehgal, Vasudha; Singhania, Richa; Han, Hee-Dong; Su, Chang; Kim, Ji Hoon; Dalton, Heather J.; Kowali, Chandra; Keyomarsi, Khandan; McMillan, Nigel A.J.; Overwijk, Willem W.; Liu, Jinsong; Lee, Ju-Seog; Baggerly, Keith A.; Lopez-Berestein, Gabriel; Ram, Prahlad T.; Nawrot, Barbara; Sood, Anil K.

2014-01-01

Improving small interfering RNA (siRNA) efficacy in target cell populations remains a challenge to its clinical implementation. Here, we report a chemical modification, consisting of phosphorodithioate (PS2) and 2’-O-Methyl (2’-OMe) MePS2 on one nucleotide that significantly enhances potency and resistance to degradation for various siRNAs. We find enhanced potency stems from an unforeseen increase in siRNA loading to the RNA-induced silencing complex, likely due to the unique interaction mediated by 2’-OMe and PS2. We demonstrate the therapeutic utility of MePS2 siRNAs in chemoresistant ovarian cancer mouse models via targeting GRAM Domain Containing 1B (GRAMD1B), a protein involved in chemoresistance. GRAMD1B silencing is achieved in tumors following MePS2-modified siRNA treatment, leading to a synergistic anti-tumor effect in combination with paclitaxel. Given the previously limited success in enhancing siRNA potency with chemically modified siRNAs, our findings represent an important advance in siRNA design with the potential for application in numerous cancer types. PMID:24619206
Investigation of Near-Surface Defects Induced by Spike Rapid Thermal Annealing in c-SILICON Solar Cells

Science.gov (United States)

Liu, Guodong; Ren, Pan; Zhang, Dayong; Wang, Weiping; Li, Jianfeng

2016-01-01

The defects induced by a spike rapid thermal annealing (RTA) process in crystalline silicon (c-Si) solar cells were investigated by the photoluminescence (PL) technique and the transmission electron microscopy (TEM), respectively. Dislocation defects were found to form in the near-surface junction region of the monocrystalline Si solar cell after a spike RTA process was performed at 1100∘C. Photo J-V characteristics were measured on the Si solar cell before and after the spike RTA treatments to reveal the effects of defects on the Si cell performances. In addition, the Silvaco device simulation program was used to study the effects of defects density on the cell performances by fitting the experimental data of RTA-treated cells. The results demonstrate that there was an obvious degradation in the Si solar cell performances when the defect density after the spike RTA treatment was above 1×1013cm-3.
Growth of gallium nitride based devices on silicon(001) substrates by metalorganic vapor phase epitaxy; Wachstum von Galliumnitrid-basierten Bauelementen auf Silizium(001)-Substraten mittels metallorganischer Gasphasenepitaxie

Energy Technology Data Exchange (ETDEWEB)

Reiher, Fabian

2009-02-25

The main topic of this thesis is to investigate GaN-based layer systems grown by metalorganic vapor phase epitaxy on Si(001) substrates. A temperature shift up to 45 K is measured for a complete device structure on a 2-inch silicon substrate. By using a 40 nm thin LT-AlN-seed layer (680 C), the GaN crystallites on Si(001) substrates are almost oriented with their GaN(10 anti 12)-planes parallel to the Si(001)-plane. A four-fold azimuthal symmetry occurs for these layers, with the GaN[10 anti 11]-direction is aligned parallel to one of the four equivalent left angle 110 right angle -directions, respectively. However, a mono-crystalline and fully coalesced GaN-layer with this crystallographic orientation could not yet been obtained. If a deposition temperature of more than 1100 C is used for the AlN-seed layer, solely the GaN[0001]- growth direction of crystallites occurs in the main GaN layer on Si(001) substrates. These c-axis oriented GaN columns feature two opposite azimuthal alignments that are rotated by 90 with respect to each other and with GaN[11 anti 20] parallel Si[110] and GaN[10 anti 10] parallel Si[110], respectively. By using 4 off-oriented substrates towards the Si[110]-direction, one certain azimuthal texture component can be selected. The critical value of the miscut angle corresponds to theoretical calculations predicting the occurrence of atomic double steps on the Si(001) surface. The achieved crystallographic quality of the GaN layers on Si(001) is characterized by having a tilt of FWHM=0.27 and a twist of FWHM=0.8 of the crystallites, determined by X-ray diffraction. A completely crack-free, up to 2.5 {mu}m thick, and mono-crystalline GaN-template can be realized on Si(001), integrating 4 or 5 LT-AlN-interlayers in the GaN buffer structure. Based on this structure, the first successful implementation of an (InGaN/GaN)-LED on Si(001) is achieved. Furthermore, the possible fabrication of GaN-based FET-structures is demonstrated with a fully
Determination of the sputter rate variation pattern of a silicon carbide target for radio frequency magnetron sputtering using optical transmission measurements

International Nuclear Information System (INIS)

Galvez de la Puente, G.; Guerra Torres, J.A.; Erlenbach, O.; Steidl, M.; Weingaertner, R.; De Zela, F.; Winnacker, A.

2010-01-01

We produce amorphous silicon carbide thin films (a-SiC) by radio frequency (rf) magnetron sputtering from SiC bulk target. We present the emission pattern of the rf magnetron with SiC target as a function of process parameters, like target sample distance, rf power, sputtering rate and process gas pressure. The emission pattern is determined by means of thickness distribution of the deposited a-SiC films obtained from optical transmission measurements using a slightly improved method of Swanepoel concerning the determination of construction of the envelopes in the interference pattern of the transmission spectra. A calibration curve is presented which allows the conversion of integrated transmission to film thickness. Holding constant a set of process parameters and only varying the target sample distance the emission pattern of the rf magnetron with SiC target was determined, which allowed us to predict the deposition rate distribution for a wide range of process parameters and target geometry. In addition, we have found that the transmission spectra of the a-SiC films change with time and saturate after approximately 10 days. Within this process no change in thickness is involved, so that the determination of thickness using transmission data is justified.

Targeted chimera delivery to ovarian cancer cells by heterogeneous gold magnetic nanoparticle

Science.gov (United States)

Chen, Yao; Xu, Mengjiao; Guo, Yi; Tu, Keyao; Wu, Weimin; Wang, Jianjun; Tong, Xiaowen; Wu, Wenjuan; Qi, Lifeng; Shi, Donglu

2017-01-01

Efficient delivery of small interfering RNAs (siRNAs) to the targeted cells has remained a significant challenge in clinical applications. In the present study, we developed a novel aptamer-siRNA chimera delivery system mediated by cationic Au-Fe3O4 nanoparticles (NPs). The chimera constructed by VEGF RNA aptamer and Notch3 siRNA was bonded with heterogeneous Au-Fe3O4 nanoparticles by electrostatic interaction. The obtained complex exhibited much higher silencing efficiency against Notch3 gene compared with chimera alone and lipofectamine-siRNA complex, and improved the antitumor effects of the loaded chimera. Moreover, the efficient delivery of the chimera by Au-Fe3O4 NPs could reverse multi-drug resistance (MDR) of ovarian cancer cells against the chemotherapeutic drug cisplatin, indicating its potential capability for future targeted cancer therapy while overcoming MDR.
Optimization of in-target yields for RIB production: Part 1: direct targets

International Nuclear Information System (INIS)

Chabod, S.; Thiolliere, N.; David, J.Ch.; Dore, D.; Ene, D.; Rapp, B.; Ridikas, D.; Chabod, S.; Blideanu, V.

2008-03-01

In the framework of the EURISOL-DS project and within Task-11, we have performed in-target yield calculations for different configurations of thick direct targets. The target materials tested are Al 2 O 3 , SiC, Pb(molten), Ta and UC 3 . The target was irradiated with protons of 0.5, 1.0, 1.5 and 2.0 GeV. The production rates have been computed using the MCNPX transport/generation code, coupled with the CINDER-90 evolution program. The yield distributions as a function of charge number Z and mass number A have been evaluated. Their production rates have been optimized for 11 selected elements (Li, Be, Ne, Mg, Ar, Ni, Ga, Kr, Hg, Sn and Fr) and 23 of their isotopes of interest. Finally, the isotopic distributions for each of these 11 elements have been optimized in terms of the target material, its geometry, and incident proton energy
Stability analysis of SiO2/SiC multilayer coatings

International Nuclear Information System (INIS)

Fu Zhiqiang; Jean-Charles, R.

2006-01-01

The stability behaviours of SiC coatings and SiO 2 /SiC coatings in helium with little impurities are studied by HSC Chemistry 4.1, the software for analysis of Chemical reaction and equilibrium in multi-component complex system. It is found that in helium with a low partial pressure of oxidative impurities under different total pressure, the key influence factor controlling T cp of SiC depends is the partial pressure of oxidative impurities; T cp of SiC increases with the partial pressure of oxidative impurities. In helium with a low partial pressure of different impurities, the key influence factor of T cs of SiO 2 are both the partial pressure of impurities and the amount of impurities for l mol SiO 2 ; T cs of SiO 2 increases with the partial pressure of oxidative impurities at the same amount of the impurities for 1 mol SiO 2 while it decreases with the amount of the impurities for 1 mm SiO 2 at the same partial pressure of the impurities. The influence of other impurities on T cp of SiC in He-O 2 is studied and it is found that CO 2 , H 2 O and N-2 increase T cp of SiC in He-O 2 while H 2 , CO and CH 4 decrease T cp of SiC He-O 2 . When there exist both oxidative impurities and reductive impurities, their effect on T cs of SiO 2 can be suppressed by the other. In HTR-10 operation atmosphere, SiO 2 /SiC coatings can keep stable status at higher temperature than SiC coatings, so SiO 2 /SiC coatings is more suitable to improve the oxidation resistance of graphite in HTR-10 operation atmosphere compared with SiC coatings. (authors)
Si-O-Si bond-angle distribution in vitreous silica from first-principles 29Si NMR analysis

International Nuclear Information System (INIS)

Mauri, Francesco; Pasquarello, Alfredo; Pfrommer, Bernd G.; Yoon, Young-Gui; Louie, Steven G.

2000-01-01

The correlation between 29 Si chemical shifts and Si-O-Si bond angles in SiO 2 is determined within density-functional theory for the full range of angles present in vitreous silica. This relation closely reproduces measured shifts of crystalline polymorphs. The knowledge of the correlation allows us to reliably extract from the experimental NMR spectrum the mean (151 degree sign ) and the standard deviation (11 degree sign ) of the Si-O-Si angular distribution of vitreous silica. In particular, we show that the Mozzi-Warren Si-O-Si angular distribution is not consistent with the NMR data. This analysis illustrates the potential of our approach for structural determinations of silicate glasses. (c) 2000 The American Physical Society
Relation between size-distribution of Si nanoparticles and oscillation-stabilization time of the mixed region produced during laser ablation

International Nuclear Information System (INIS)

Wang Yinglong; Li Yanli; Fu Guangsheng

2006-01-01

Assuming Si particles and ambient atoms are elastic hard-spheres, the transportation in ambient gas of Si particles obtained by single-pulsed laser ablation is numerically simulated via Monte Carlo method to investigate the influence of the ambient species and the target-to-substrate distance on the oscillation-stabilization time (OST) of the mixed region. It is found that the ambient gas whose atomic weight is close to that of Si atom can induce the shortest OST; with increasing of the target-to-substrate distance, the OST at first decreases to its minimum, and then begins to increase. Incorporating with some experimental results on size-consistency of Si nanoparticles in pulsed laser ablation, it may be concluded that the shorter the OST of the mixed region, the more uniform the as-formed Si nanoparticles in size
Si-O compound formation by oxygen ion implantation into silicon

International Nuclear Information System (INIS)

Hensel, E.; Wollschlaeger, K.; Kreissig, U.; Skorupa, W.; Schulze, D.; Finster, J.

1985-01-01

High dose oxygen ion implantation into silicon at 30 keV was performed to produce understoichiometric and stoichiometric surface oxide layers of approx. 160 nm thickness. The oxygen depth profile and oxide stoichiometry was determined by RBS and XPS. Si-O compound formation was found by IR spectroscopy and XPS in the unannealed samples as well as after target heating, furnace or flash lamp annealing. As implanted understoichiometric layers consist of random bonding like SiOsub(x) (O 2 after annealing. Unannealed stoichiometric layers are bond strained SiO 2 . The activation energies of demixing and of the annealing of bond strains are determined to 0.19 and 0.13 eV, respectively. The removing of bond strains occurs at temperatures >= 800 C in a time shorter than 1 s. The SiO 2 /Si transition region of unannealed stoichiometric layers consists of SiOsub(x) with an extent of about 10 nm. After annealing this extent diminishes to 0.8 to 1 nm in consequence of oxidation by excess oxygen from the overstoichiometric oxide region. This thickness is comparable with that of thermal oxide. (author)
Computer simulation of range and damage distributions of He ions in SiC

International Nuclear Information System (INIS)

Miyagawa, Yoshiko; Ato, Yasuro; Miyagawa, Soji

1984-01-01

The experimental projected ranges of various heavy ions in an amorphous Si target in the energy region where the nuclear stopping dominates are compared with calculations using the computer simulation program SASAMAL with the Lenz-Jensen, Moliere, Thomas-Fermi and Kalbitzer-Oetzmann (KO) screening parameters. In most cases. the best agreement was obtained with the KO screening parameters. The projected range distributions of He ions implanted in an SiC target were calculated using SASAMAL with KO screening parameters. The agreement between the SASAMAL(KO) results and our experimental data was satisfactory when the electronic stopping parameter k=1.3 k sub(NS) was used. The energy and the depth distributions of the primary knock-on atoms and the depth distributions of the recoil energy density with various values of the displacement energy Esub(d) were also calculated using SASAMAL(KO) for He ions in SiC. (author)
Interfacial microstructure of NiSi x/HfO2/SiO x/Si gate stacks

International Nuclear Information System (INIS)

Gribelyuk, M.A.; Cabral, C.; Gusev, E.P.; Narayanan, V.

2007-01-01

Integration of NiSi x based fully silicided metal gates with HfO 2 high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi x film. Ni content varies near the NiSi/HfO x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi x /HfO 2 interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi x /HfO x was found higher than that of poly-Si/HfO 2 , likely due to compositional non-uniformity of NiSi x . No intermixing between Hf, Ni and Si beyond interfacial roughness was observed
Silicon Carbide (SiC) Power Processing Unit (PPU) for Hall Effect Thrusters

Science.gov (United States)

Reese, Bradley

2015-01-01

Arkansas Power Electronics International (APEI), Inc., is developing a high-efficiency, radiation-hardened 3.8-kW SiC power supply for the PPU of Hall effect thrusters. This project specifically targets the design of a PPU for the high-voltage Hall accelerator (HiVHAC) thruster, with target specifications of 80- to 160-V input, 200- to 700-V/5A output, efficiency greater than 96 percent, and peak power density in excess of 2.5 kW/kg. The PPU under development uses SiC junction field-effect transistor power switches, components that APEI, Inc., has irradiated under total ionizing dose conditions to greater than 3 MRad with little to no change in device performance.
Luminescence properties of Si-capped β-FeSi{sub 2} nanodots epitaxially grown on Si(001) and (111) substrates

Energy Technology Data Exchange (ETDEWEB)

Amari, Shogo; Ichikawa, Masakazu [Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakamura, Yoshiaki, E-mail: nakamura@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); PRESTO, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan)

2014-02-28

We studied the luminescence properties of Si-capped β-FeSi{sub 2} nanodots (NDs) epitaxially grown on Si substrates by using photoluminescence (PL) and electroluminescence (EL) spectroscopies. Codepositing Fe and Si on ultrathin SiO{sub 2} films induced the self-assembly of epitaxial β-FeSi{sub 2} NDs. The PL spectra of the Si/β-FeSi{sub 2} NDs/Si structure depended on the crystal orientation of the Si substrate. These structures exhibited a broad PL peak near 0.8 eV on both Si(001) and (111) substrates. The PL intensity depended on the shape of the β-FeSi{sub 2} NDs. For the flat NDs, which exhibited higher PL intensity, we also recorded EL spectra. We explained the luminescence properties of these structures by the presence of nanostructured Si offering radiative electronic states in the Si cap layers, generated by nano-stressors for upper Si layer: the strain-relaxed β-FeSi{sub 2} NDs.
Thermal shock properties of 2D-SiCf/SiC composites

International Nuclear Information System (INIS)

Lee, Sang Pill; Lee, Jin Kyung; Son, In Soo; Bae, Dong Su; Kohyama, Akira

2012-01-01

This paper dealt with the thermal shock properties of SiC f /SiC composites reinforced with two dimensional SiC fabrics. SiC f /SiC composites were fabricated by a liquid phase sintering process, using a commercial nano-size SiC powder and oxide additive materials. An Al 2 O 3 –Y 2 O 3 –SiO 2 powder mixture was used as a sintering additive for the consolidation of SiC matrix region. In this composite system, Tyranno SA SiC fabrics were also utilized as a reinforcing material. The thermal shock test for SiC f /SiC composites was carried out at the elevated temperature. Both mechanical strength and microstructure of SiC f /SiC composites were investigated by means of optical microscopy, SEM and three point bending test. SiC f /SiC composites represented a dense morphology with a porosity of about 8.2% and a flexural strength of about 160 MPs. The characterization of SiC f /SiC composites was greatly affected by the history of cyclic thermal shock. Especially, SiC f /SiC composites represented a reduction of flexural strength at the thermal shock temperature difference higher than 800 °C.
SiRNA-mediated IGF-1R inhibition sensitizes human colon cancer SW480 cells to radiation

International Nuclear Information System (INIS)

Yavari, Kamal; Taghikhani, Mohammad; Mesbah-Namin, Seyed A.; Maragheh, Mohammad Ghannadi; Babaei, Mohammad Hosein; Arfaee, Ali Jabbary; Madani, Hossein; Mirzaei, Hamid Reza

2010-01-01

Purpose. Insulin like growth factor receptor 1 (IGF-1R) is well-documented to play a key role in radiation response and tumor radiosensitivity, thus offering an attractive clinic drug target to enhance tumor sensitivity to anti-cancer radiotherapy. Material and methods. Human colon carcinoma SW480 cells were transfected with the specific small interference RNA (siRNA) expression vector (pkD-shRNA-IGF-1R-V2) designed to target IGF-1R mRNA. The expression of IGF-1R mRNA and its protein among the transfected and untransfected cells were detected by semi-quantitative RT-PCR and ELISA assay. The changes in cell radiosensitivity were examined by MTT assay. Results. Transfection of mammalian expression vector pkD containing IGF-1R siRNA was shown to reduce IGF-1R mRNA levels by up to 95%. ELISA assay detected a similar inhibition of IGF-1R protein levels in cells transfected with IGF-1R siRNA. SW480 cells transfected with the expression vector for siRNA significantly rendered cells more sensitive to radiation and the highest radiation enhancement ratio was 2.02 ± 0.08. Conclusion. These data provide the first evidence that specific siRNA fragment (pkD-shRNA-IGF-1R-V2) targeting human IGF-1R mRNA is able to enhance colon cancer radiosensitivity. Also results indicated that, combining IGF-1R siRNA and radiation significantly enhances antitumor efficacy compared with either modality alone
A MSLN-targeted multifunctional nanoimmunoliposome for MRI and targeting therapy in pancreatic cancer

Directory of Open Access Journals (Sweden)

Deng L

2012-09-01

efficient uptake of M-PLDU in Panc-1 cells by antibody-mediated targeting. Methyl thiazolyl tetrazolium assay results showed significant inhibitory effect of M-PLDU against Panc-1 cells (half-maximal inhibitory concentration, 1.95 µM. The in vivo imaging study showed that the tumor signal intensity (SI dropped significantly about 4 hours after intravenous injection of M-PLDU. The decrease in tumor SI induced by M-PLDUs (∆ SI = 145.98 ± 20.45 or PLDUs (∆ SI = 75.69 ± 14.53 was much more significant than that by free USPIOs (∆ SI = 42.78 ± 22.12; P < 0.01. The in vivo antitumor study demonstrated that compared with FD (free DOX and PLDU, M-PLDU possessed higher inhibitory effect on tumor growth and the tissue distribution assay further proved that M-PLDUs could selectively accumulate in the tumor xenograft. These results indicated that M-PLDU not only well retained the inherent MRI capability of USPIOs, but significantly improved the targeting distribution of USPIOs and therapeutic agents in pancreatic tumor tissues. They may serve as a promising theranostic nanomedicine not only for early detection but also for MRI-monitored targeting therapy of human pancreatic cancer.Keywords: theranostic nanomedicine, nanoimmunoliposome, mesothelin, USPIO, doxorubicin, pancreatic cancer
SiC/SiC Cladding Materials Properties Handbook

Energy Technology Data Exchange (ETDEWEB)

Snead, Mary A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Katoh, Yutai [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Koyanagi, Takaaki [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Singh, Gyanender P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-01

When a new class of material is considered for a nuclear core structure, the in-pile performance is usually assessed based on multi-physics modeling in coordination with experiments. This report aims to provide data for the mechanical and physical properties and environmental resistance of silicon carbide (SiC) fiber–reinforced SiC matrix (SiC/SiC) composites for use in modeling for their application as accidenttolerant fuel cladding for light water reactors (LWRs). The properties are specific for tube geometry, although many properties can be predicted from planar specimen data. This report presents various properties, including mechanical properties, thermal properties, chemical stability under normal and offnormal operation conditions, hermeticity, and irradiation resistance. Table S.1 summarizes those properties mainly for nuclear-grade SiC/SiC composites fabricated via chemical vapor infiltration (CVI). While most of the important properties are available, this work found that data for the in-pile hydrothermal corrosion resistance of SiC materials and for thermal properties of tube materials are lacking for evaluation of SiC-based cladding for LWR applications.
Saccadic distractor effects: the remote distractor effect (RDE) and saccadic inhibition (SI): A response to McIntosh and Buonocore (2014).

Science.gov (United States)

Walker, Robin; Benson, Valerie

2015-02-04

We (Walker & Benson, 2013) reported studies in which the spatial effects of distractors on the remote distractor effect (RDE) and saccadic inhibition (SI) were examined. Distractors remote from the target increased mean latency and the skew of the distractor-related distributions, without the presence of dips that are regarded as the hallmark of SI. We further showed that early onset distractors had similar effects although these would not be consistent with existing estimates of the duration of SI (of around 60-70 ms). McIntosh and Buonocore (2014) report a simulation showing that skewed latency distributions can arise from the putative SI mechanism and they also highlighted a number of methodological considerations regarding the RDE and SI as measures of saccadic distractor effects (SDEs). Here we evaluate these claims and note that the measures of SI obtained by subtracting latency distributions (specifically the decrease in saccade frequency--or dip duration) are no more diagnostic of a single inhibitory process, or more sensitive indicators of it, than is median latency. Furthermore the evidence of inhibitory influences of small distractors presented close to the target is incompatible with the explanations of both the RDE and SI. We conclude that saccadic distractor effects may be a more inclusive term to encompass the different characteristics of behavioral effects of underlying saccade target selection. © 2015 ARVO.
Continuous Acoustic Sensing With an Unmanned Aerial Vehicle System for Anti-Submarine Warfare in a High-Threat Area

Science.gov (United States)

2015-12-01

utilize the sonobuoy at all. Overall, this technology needs to be updated and improved Now imagine a sonobuoy powered by sonar panels , increasing its...cell array uses monocrystalline Si SunPower E60 cells with roughly 24% efficiency. These cells are the sole source of energy for all operations of...solar panels there is a watertight enclosure that will hold all of the electronics that includes both the processor and power board. This
Novel pH-sensitive multifunctional envelope-type nanodevice for siRNA-based treatments for chronic HBV infection.

Science.gov (United States)

Yamamoto, Naoki; Sato, Yusuke; Munakata, Tsubasa; Kakuni, Masakazu; Tateno, Chise; Sanada, Takahiro; Hirata, Yuichi; Murakami, Shuko; Tanaka, Yasuhito; Chayama, Kazuaki; Hatakeyama, Hiroto; Hyodo, Mamoru; Harashima, Hideyoshi; Kohara, Michinori

2016-03-01

Antiviral agents including entecavir (ETV) suppress the replication of the hepatitis B virus (HBV) genome in human hepatocytes, but they do not reduce the abundance of viral proteins. The present study focused on effectively reducing viral protein levels. We designed siRNAs (HBV-siRNA) that target consensus sequences in HBV genomes. To prevent the emergence of escaped mutant virus, we mixed three HBV-siRNAs (HBV-siRNAmix); the mixture was encapsulated in a novel pH-sensitive multifunctional envelope-type nanodevice (MEND), a hepatocyte-specific drug delivery system. Coagulation factor 7 siRNA was used to assess delivery and knockdown efficiencies of MEND/siRNA treatments in mice. The potency of MEND/HBV-siRNAmix was evaluated in primary human hepatocytes and in chimeric mice with humanized liver persistently infected with HBV. Effective knockdown of targets, efficient delivery of siRNA, and liver-specific delivery were each observed with MEND. MEND/HBV-siRNA caused efficient reduction of HBsAg and HBeAg in vitro and in vivo. However, ETV treatment did not efficiently reduce HBsAg or HBeAg when compared with a single MEND/HBV-siRNAmix treatment. Furthermore, the suppressive effects of a single dose of MEND/HBV-siRNAmix persisted for 14days in vitro and in vivo. We demonstrated that MEND/HBV-siRNA controlled HBV more efficiently than did ETV. Furthermore, the effect of a single dose of MEND/HBV-siRNA persisted for a long time. These results indicated that MEND/HBV-siRNA may be a promising novel HBV treatment that is more effective than reverse transcriptase inhibitors. Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.
Exceptional cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si heterostructures

Science.gov (United States)

Chen, Da; Wang, Dadi; Chang, Yongwei; Li, Ya; Ding, Rui; Li, Jiurong; Chen, Xiao; Wang, Gang; Guo, Qinglei

2018-01-01

The cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si structures after thermal annealing was investigated. The crack formation position is found to closely correlate with the thickness of the buried Si0.70Ge0.30 layer. For H-implanted Si containing a buried 3-nm-thick B-doped Si0.70Ge0.30 layer, localized continuous cracking occurs at the interfaces on both sides of the Si0.70Ge0.30 interlayer. Once the thickness of the buried Si0.70Ge0.30 layer increases to 15 and 70 nm, however, a continuous sharp crack is individually observed along the interface between the Si substrate and the B-doped Si0.70Ge0.30 interlayer. We attribute this exceptional cracking behavior to the existence of shear stress on both sides of the buried Si0.70Ge0.30 layer and the subsequent trapping of hydrogen, which leads to a crack in a well-controlled manner. This work may pave the way for high-quality Si or SiGe membrane transfer in a feasible manner, thus expediting its potential applications to ultrathin silicon-on-insulator (SOI) or silicon-germanium-on-insulator (SGOI) production.
Small interfering RNA targeting HIF-1{alpha} reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Staab, Adrian [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Paul Scherrer Institute (PSI), Villigen (Switzerland); Fleischer, Markus [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Wuerzburg Univ. (Germany). Medical Clinic II; Loeffler, Juergen; Einsele, Herrmann [Wuerzburg Univ. (Germany). Medical Clinic II; Said, Harun M.; Katzer, Astrid; Flentje, Michael [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Plathow, Christian [Freiburg Univ. (Germany). Dept. of Nuclear Medicine; Vordermark, Dirk [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; Halle-Wittenberg Univ. (Germany). Dept. of Radiation Oncology

2011-04-15

Background: Hypoxia inducible factor-1 has been identified as a potential target to overcome hypoxia-induced radioresistance The aim of the present study was to investigate whether selective HIF-1 inhibition via small interfering RNA (siRNA) targeting hypoxia-inducible factor 1{alpha} (HIF-1{alpha}) affects hypoxia-induced radioresistance in HT 1080 human fibrosarcoma cells. Material and Methods: HIF-1{alpha} expression in HT 1080 human fibrosarcoma cells in vitro was silenced using HIF-1{alpha} siRNA sequence primers. Quantitative real-time polymerase chain reaction assay was performed to quantify the mRNA expression of HIF-1{alpha}. HIF-1{alpha} protein levels were studied by Western blotting at 20% (air) or after 12 hours at 0.1% O{sub 2} (hypoxia). Cells were assayed for clonogenic survival after irradiation with 2, 5, or 10 Gy, under normoxic or hypoxic conditions in the presence of HIF-1{alpha}-targeted or control siRNA sequences. A modified oxygen enhancement ratio (OER') was calculated as the ratio of the doses to achieve the same survival at 0.1% O{sub 2} as at ambient oxygen tensions. OER' was obtained at cell survival levels of 50%, 37%, and 10%. Results: HIF-1{alpha}-targeted siRNA enhanced radiation treatment efficacy under severely hypoxic conditions compared to tumor cells treated with scrambled control siRNA. OER was reduced on all survival levels after treatment with HIF-1{alpha}-targeted siRNA, suggesting that inhibition of HIF-1 activation by using HIF-1{alpha}-targeted siRNA increases radiosensitivity of hypoxic tumor cells in vitro. Conclusion: Inhibition of HIF-1 activation by using HIF-1{alpha}-targeted siRNA clearly acts synergistically with radiotherapy and increase radiosensitivity of hypoxic cells in vitro. (orig.)
Small interfering RNA targeting HIF-1α reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro

International Nuclear Information System (INIS)

Staab, Adrian; Fleischer, Markus; Wuerzburg Univ.; Loeffler, Juergen; Einsele, Herrmann; Said, Harun M.; Katzer, Astrid; Flentje, Michael; Plathow, Christian; Vordermark, Dirk; Halle-Wittenberg Univ.

2011-01-01

Background: Hypoxia inducible factor-1 has been identified as a potential target to overcome hypoxia-induced radioresistance The aim of the present study was to investigate whether selective HIF-1 inhibition via small interfering RNA (siRNA) targeting hypoxia-inducible factor 1α (HIF-1α) affects hypoxia-induced radioresistance in HT 1080 human fibrosarcoma cells. Material and Methods: HIF-1α expression in HT 1080 human fibrosarcoma cells in vitro was silenced using HIF-1α siRNA sequence primers. Quantitative real-time polymerase chain reaction assay was performed to quantify the mRNA expression of HIF-1α. HIF-1α protein levels were studied by Western blotting at 20% (air) or after 12 hours at 0.1% O 2 (hypoxia). Cells were assayed for clonogenic survival after irradiation with 2, 5, or 10 Gy, under normoxic or hypoxic conditions in the presence of HIF-1α-targeted or control siRNA sequences. A modified oxygen enhancement ratio (OER') was calculated as the ratio of the doses to achieve the same survival at 0.1% O 2 as at ambient oxygen tensions. OER' was obtained at cell survival levels of 50%, 37%, and 10%. Results: HIF-1α-targeted siRNA enhanced radiation treatment efficacy under severely hypoxic conditions compared to tumor cells treated with scrambled control siRNA. OER was reduced on all survival levels after treatment with HIF-1α-targeted siRNA, suggesting that inhibition of HIF-1 activation by using HIF-1α-targeted siRNA increases radiosensitivity of hypoxic tumor cells in vitro. Conclusion: Inhibition of HIF-1 activation by using HIF-1α-targeted siRNA clearly acts synergistically with radiotherapy and increase radiosensitivity of hypoxic cells in vitro. (orig.)

High-throughput screening of effective siRNAs using luciferase-linked chimeric mRNA.

Directory of Open Access Journals (Sweden)

Shen Pang

Full Text Available The use of siRNAs to knock down gene expression can potentially be an approach to treat various diseases. To avoid siRNA toxicity the less transcriptionally active H1 pol III promoter, rather than the U6 promoter, was proposed for siRNA expression. To identify highly efficacious siRNA sequences, extensive screening is required, since current computer programs may not render ideal results. Here, we used CCR5 gene silencing as a model to investigate a rapid and efficient screening approach. We constructed a chimeric luciferase-CCR5 gene for high-throughput screening of siRNA libraries. After screening approximately 900 shRNA clones, 12 siRNA sequences were identified. Sequence analysis demonstrated that most (11 of the 12 sequences of these siRNAs did not match those identified by available siRNA prediction algorithms. Significant inhibition of CCR5 in a T-lymphocyte cell line and primary T cells by these identified siRNAs was confirmed using the siRNA lentiviral vectors to infect these cells. The inhibition of CCR5 expression significantly protected cells from R5 HIV-1JRCSF infection. These results indicated that the high-throughput screening method allows efficient identification of siRNA sequences to inhibit the target genes at low levels of expression.
Pokemon siRNA Delivery Mediated by RGD-Modified HBV Core Protein Suppressed the Growth of Hepatocellular Carcinoma.

Science.gov (United States)

Kong, Jing; Liu, Xiaoping; Jia, Jianbo; Wu, Jinsheng; Wu, Ning; Chen, Jun; Fang, Fang

2015-10-01

Hepatocellular carcinoma (HCC) is a deadly human malignant tumor that is among the most common cancers in the world, especially in Asia. Hepatitis B virus (HBV) infection has been well established as a high risk factor for hepatic malignance. Studies have shown that Pokemon is a master oncogene for HCC growth, suggesting it as an ideal therapeutic target. However, efficient delivery system is still lacking for Pokemon targeting treatment. In this study, we used core proteins of HBV, which is modified with RGD peptides, to construct a biomimetic vector for the delivery of Pokemon siRNAs (namely, RGD-HBc-Pokemon siRNA). Quantitative PCR and Western blot assays revealed that RGD-HBc-Pokemon siRNA possessed the highest efficiency of Pokemon suppression in HCC cells. In vitro experiments further indicated that RGD-HBc-Pokemon-siRNA exerted a higher tumor suppressor activity on HCC cell lines, evidenced by reduced proliferation and attenuated invasiveness, than Pokemon-siRNA or RGD-HBc alone. Finally, animal studies demonstrated that RGD-HBc-Pokemon siRNA suppressed the growth of HCC xenografts in mice by a greater extent than Pokemon-siRNA or RGD-HBc alone. Based on the above results, Pokemon siRNA delivery mediated by RGD-modified HBV core protein was shown to be an effective strategy of HCC gene therapy.
Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process

Science.gov (United States)

Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

2017-11-01

The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.
Observations on Si-based micro-clusters embedded in TaN thin film deposited by co-sputtering with oxygen contamination

Energy Technology Data Exchange (ETDEWEB)

Lee, Young Mi [Beamline Division, Pohang Accelerator Laboratory, POSTECH, Pohang, 305-764 (Korea, Republic of); Jung, Min-Sang; Choi, Duck-Kyun, E-mail: duck@hanyang.ac.kr, E-mail: mcjung@oist.jp [Department of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Jung, Min-Cherl, E-mail: duck@hanyang.ac.kr, E-mail: mcjung@oist.jp [Energy Materials and Surface Sciences Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, 904-0495 (Japan)

2015-08-15

Using scanning electron microscopy (SEM) and high-resolution x-ray photoelectron spectroscopy with the synchrotron radiation we investigated Si-based micro-clusters embedded in TaSiN thin films having oxygen contamination. TaSiN thin films were deposited by co-sputtering on fixed or rotated substrates and with various power conditions of TaN and Si targets. Three types of embedded micro-clusters with the chemical states of pure Si, SiO{sub x}-capped Si, and SiO{sub 2}-capped Si were observed and analyzed using SEM and Si 2p and Ta 4f core-level spectra were derived. Their different resistivities are presumably due to the different chemical states and densities of Si-based micro-clusters.
Observations on Si-based micro-clusters embedded in TaN thin film deposited by co-sputtering with oxygen contamination

Directory of Open Access Journals (Sweden)

Young Mi Lee

2015-08-01

Full Text Available Using scanning electron microscopy (SEM and high-resolution x-ray photoelectron spectroscopy with the synchrotron radiation we investigated Si-based micro-clusters embedded in TaSiN thin films having oxygen contamination. TaSiN thin films were deposited by co-sputtering on fixed or rotated substrates and with various power conditions of TaN and Si targets. Three types of embedded micro-clusters with the chemical states of pure Si, SiOx-capped Si, and SiO2-capped Si were observed and analyzed using SEM and Si 2p and Ta 4f core-level spectra were derived. Their different resistivities are presumably due to the different chemical states and densities of Si-based micro-clusters.
Infrared spectroscopic and voltammetric study of adsorbed CO on stepped surfaces of copper monocrystalline electrodes

International Nuclear Information System (INIS)

Koga, O.; Teruya, S.; Matsuda, K.; Minami, M.; Hoshi, N.; Hori, Y.

2005-01-01

Voltammetric and infrared (IR) spectroscopic measurements were carried out to study adsorbed CO on two series of copper single crystal electrodes n(111)-(111) and n(111)-(100) in 0.1M KH 2 PO 4 +0.1M K 2 HPO 4 at 0 o C. Reversible voltammetric waves were observed below -0.55V versus SHE for adsorption of CO which displaces preadsorbed phosphate anions. The electric charge of the redox waves is proportional to the step atom density for both single crystal series. This fact indicates that phosphate anions are specifically adsorbed on the step sites below -0.55V versus SHE. Voltammetric measurements indicated that (111) terrace of Cu is covered with adsorbed CO below -0.5V versus SHE. Nevertheless, no IR absorption band of adsorbed CO is detected from (111) terrace. Presence of adsorbed CO on (111) terrace is presumed which is not visible by the potential difference spectroscopy used in the present work. IR spectroscopic measurements showed that CO is reversibly adsorbed with an on-top manner on copper single crystal electrodes of n(111)-(111) and n(111)-(100) with approximately same wavenumber of C?O stretching vibration of 2070cm -1 . The IR band intensity is proportional to the step atom density. Thus CO is adsorbed on (111) or (100) steps on the single crystal surfaces. An analysis of the IR band intensity suggested that one CO molecule is adsorbed on every two or more Cu step atom of the monocrystalline surface. The spectroscopic data were compared with those reported for uhv system. The C-O stretching wavenumber of adsorbed CO in the electrode-electrolyte system is 30-40cm -1 lower than those in uhv system
Electrical properties of Si/Si1-xGex/Si inverted modulation doped structures

International Nuclear Information System (INIS)

Sadeghzadeh, M.A.

1998-12-01

This thesis is a report of experimental investigations of growth strategy and electrical properties of Si/Si 1-x Ge x /Si inverted Modulation Doped (MD) structures grown by solid source Molecular Beam Epitaxy (MBE). If the grown Si layer is B-doped at some distance (as spacer) before or after the alloy layer, this remote doping induces the formation of a quasi Two Dimensional Hole Gas (2-DHG) near to the inverted (SiGe on Si) or normal (Si on SiGe) heterointerfaces of the Si/Si 1-x Ge x /Si quantum well, respectively. The latter arrangement is the well known 'normal' MD structure but the former one is the so-called 'inverted' MD structure which is of great interest for Field Effect Transistor (FET) applications. A reproducible growth strategy was employed by the use of a thick (400nm) Si cap for inverted MD structures with Ge composition in the range of 16-23%. Boron segregation and cap surface charges are significant in these inverted structures with small ( 20nm) spacer layers, respectively. It was demonstrated by secondary ion mass spectroscopy (SIMS) that boron segregation, which causes a reduction in the effective spacer dimension, can be suppressed by growth interruption after boron doping. The enhancement in hole sheet density with increasing Si cap layer thickness, is attributed to a reduction in the influence of positive surface charges in these structures. Top-gated devices were fabricated using these structures and the hole sheet density could be varied by applying a voltage to the metal-semiconductor gate, and the maximum Hall mobility of 5550 cm 2 V -1 s -1 with 4.2x10 11 cm -2 was measured (at 1.6K) in these structures. Comparison of measured Hall mobility (at 4.2K) as a function of hole sheet density in normal and inverted MD structures implies that both 2-DHG confined at normal and/or inverted structures are subjected to very similar interface charge, roughness, and alloy scattering potentials. Low temperatures magnetotransport measurements (down to
Confirming the RNAi-mediated mechanism of action of siRNA-based cancer therapeutics in mice

OpenAIRE

Judge, Adam D.; Robbins, Marjorie; Tavakoli, Iran; Levi, Jasna; Hu, Lina; Fronda, Anna; Ambegia, Ellen; McClintock, Kevin; MacLachlan, Ian

2009-01-01

siRNAs that specifically silence the expression of cancer-related genes offer a therapeutic approach in oncology. However, it remains critical to determine the true mechanism of their therapeutic effects. Here, we describe the preclinical development of chemically modified siRNA targeting the essential cell-cycle proteins polo-like kinase 1 (PLK1) and kinesin spindle protein (KSP) in mice. siRNA formulated in stable nucleic acid lipid particles (SNALP) displayed potent antitumor efficacy in b...
Abrupt GaP/Si hetero-interface using bistepped Si buffer

Energy Technology Data Exchange (ETDEWEB)

Ping Wang, Y., E-mail: yanping.wang@insa-rennes.fr; Kuyyalil, J.; Nguyen Thanh, T.; Almosni, S.; Bernard, R.; Tremblay, R.; Da Silva, M.; Létoublon, A.; Rohel, T.; Tavernier, K.; Le Corre, A.; Cornet, C.; Durand, O. [UMR FOTON, CNRS, INSA Rennes, Rennes F-35708 (France); Stodolna, J.; Ponchet, A. [CEMES-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 04 (France); Bahri, M.; Largeau, L.; Patriarche, G. [Laboratoire de Photonique et Nanostructures, CNRS UPR 20, Route de Nozay, Marcoussis 91460 (France); Magen, C. [LMA, INA-ARAID, and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain)

2015-11-09

We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth.
Abrupt GaP/Si hetero-interface using bistepped Si buffer

International Nuclear Information System (INIS)

Ping Wang, Y.; Kuyyalil, J.; Nguyen Thanh, T.; Almosni, S.; Bernard, R.; Tremblay, R.; Da Silva, M.; Létoublon, A.; Rohel, T.; Tavernier, K.; Le Corre, A.; Cornet, C.; Durand, O.; Stodolna, J.; Ponchet, A.; Bahri, M.; Largeau, L.; Patriarche, G.; Magen, C.

2015-01-01

We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth
Synthesis and structural property of Si nanosheets connected to Si nanowires using MnCl{sub 2}/Si powder source

Energy Technology Data Exchange (ETDEWEB)

Meng, Erchao [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Ueki, Akiko [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Meng, Xiang [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Suzuki, Hiroaki [Graduate School of Engineering, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Itahara, Hiroshi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Tatsuoka, Hirokazu, E-mail: tatsuoka.hirokazu@shizuoka.ac.jp [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan)

2016-08-15

Graphical abstract: Si nanosheets connected to Si nanowires synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst avoid the use of air-sensitive SiH{sub 4} or SiCl{sub 4}. It was evident from these structural features of the nanosheets (leaf blade) with nanowires (petiole) that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes of the Si(111) nanosheets was clearly explained by the interference with the extra diffraction spots that arose due to the reciprocal lattice streaking effect. - Highlights: • New Si nanosheets connected to Si nanowires were synthesized using MnCl{sub 2}/Si powders. • The synthesis method has benefits in terms of avoiding air sensitive SiH{sub 4} or SiCl{sub 4}. • Structural property and electron diffraction of the Si nanosheets were clarified. • Odd lattice fringes of the Si nanosheets observed by HRTEM were clearly explained. - Abstract: Si nanosheets connected to Si nanowires were synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst. The synthesis method has benefits in terms of avoiding conventionally used air-sensitive SiH{sub 4} or SiCl{sub 4}. The existence of the Si nanosheets connected to the Si<111> nanowires, like sprouts or leaves with petioles, was observed, and the surface of the nanosheets was Si{111}. The nanosheets were grown in the growth direction of <211> perpendicular to that of the Si nanowires. It was evident from these structural features of the nanosheets that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes, which do not appear for Si bulk crystals, of the Si(111) nanosheets obtained by high resolution transmission electron microscopy was clearly explained due to the extra diffraction spots that arose by the reciprocal lattice streaking effect.
Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process.

Science.gov (United States)

Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

2017-11-25

The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.
Si/SiGe heterointerfaces in one-, two-, and three-dimensional nanostructures: their impact on SiGe light emission

Science.gov (United States)

Lockwood, David; Wu, Xiaohua; Baribeau, Jean-Marc; Mala, Selina; Wang, Xialou; Tsybeskov, Leonid

2016-03-01

Fast optical interconnects together with an associated light emitter that are both compatible with conventional Si-based complementary metal-oxide- semiconductor (CMOS) integrated circuit technology is an unavoidable requirement for the next-generation microprocessors and computers. Self-assembled Si/Si1-xGex nanostructures, which can emit light at wavelengths within the important optical communication wavelength range of 1.3 - 1.55 μm, are already compatible with standard CMOS practices. However, the expected long carrier radiative lifetimes observed to date in Si and Si/Si1-xGex nanostructures have prevented the attainment of efficient light-emitting devices including the desired lasers. Thus, the engineering of Si/Si1-xGex heterostructures having a controlled composition and sharp interfaces is crucial for producing the requisite fast and efficient photoluminescence (PL) at energies in the range 0.8-0.9 eV. In this paper we assess how the nature of the interfaces between SiGe nanostructures and Si in heterostructures strongly affects carrier mobility and recombination for physical confinement in three dimensions (corresponding to the case of quantum dots), two dimensions (corresponding to quantum wires), and one dimension (corresponding to quantum wells). The interface sharpness is influenced by many factors such as growth conditions, strain, and thermal processing, which in practice can make it difficult to attain the ideal structures required. This is certainly the case for nanostructure confinement in one dimension. However, we demonstrate that axial Si/Ge nanowire (NW) heterojunctions (HJs) with a Si/Ge NW diameter in the range 50 - 120 nm produce a clear PL signal associated with band-to-band electron-hole recombination at the NW HJ that is attributed to a specific interfacial SiGe alloy composition. For three-dimensional confinement, the experiments outlined here show that two quite different Si1-xGex nanostructures incorporated into a Si0.6Ge0.4 wavy
Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

International Nuclear Information System (INIS)

Gueneau, C.; Ansara, I.

1994-01-01

The substitutions of Al Si, Fe Mn and Fe Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil's model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs
Ultrathin SiO{sub 2} layer formed by the nitric acid oxidation of Si (NAOS) method to improve the thermal-SiO{sub 2}/Si interface for crystalline Si solar cells

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, Taketoshi; Nakajima, Hiroki; Irishika, Daichi; Nonaka, Takaaki; Imamura, Kentaro; Kobayashi, Hikaru, E-mail: h.kobayashi@sanken.osaka-u.ac.jp

2017-02-15

Highlights: • The density of interface states at the SiO{sub 2}/Si interface is decreased by NAOS. • The minority carrier lifetime is increased by the NAOS treatment. • Great interfacial properties of the NAOS layer are kept after thermal oxidation. - Abstract: A combination of the nitric acid oxidation of Si (NAOS) method and post-thermal oxidation is found to efficiently passivate the SiO{sub 2}/n-Si(100) interface. Thermal oxidation at 925 °C and annealing at 450 °C in pure hydrogen atmosphere increases the minority carrier lifetime by three orders of magnitude, and it is attributed to elimination of Si dangling bond interface states. Fabrication of an ultrathin, i.e., 1.1 nm, NAOS SiO{sub 2} layer before thermal oxidation and H{sub 2} annealing further increases the minority carrier lifetime by 30% from 8.6 to 11.1 ms, and decreased the interface state density by 10% from 6.9 × 10{sup 9} to 6.3 × 10{sup 9}eV{sup −1} cm{sup −2}. After thermal oxidation at 800 °C, the SiO{sub 2} layer on the NAOS-SiO{sub 2}/Si(100) structure is 2.26 nm thick, i.e., 0.24 nm thicker than that on the Si(100) surface, while after thermal oxidation at 925 °C, it is 4.2 nm thick, i.e., 0.4 nm thinner than that on Si(100). The chemical stability results from the higher atomic density of a NAOS SiO{sub 2} layer than that of a thermal oxide layer as reported in Ref. [28] (Asuha et al., 2002). Higher minority carrier lifetime in the presence of the NAOS layer indicates that the NAOS-SiO{sub 2}/Si interface with a low interface state density is preserved after thermal oxidation, which supports out-diffusion oxidation mechanism, by which a thermal oxide layer is formed on the NAOS SiO{sub 2} layer.
Comparison of interfaces for (Ba,Sr)TiO3 films deposited on Si and SiO2/Si substrates

International Nuclear Information System (INIS)

Suvorova, N.A.; Lopez, C.M.; Irene, E.A.; Suvorova, A.A.; Saunders, M.

2004-01-01

(Ba,Sr)TiO 3 (BST) thin films were deposited by ion sputtering on both bare and oxidized Si. Spectroscopic ellipsometry results have shown that a SiO 2 underlayer of nearly the same thickness (2.6 nm in average) is found at the Si interface for BST sputter depositions onto nominally bare Si, 1 nm SiO 2 on Si or 3.5 nm SiO 2 on Si. This result was confirmed by high-resolution electron microscopy analysis of the films, and it is believed to be due to simultaneous subcutaneous oxidation of Si and reaction of the BST layer with SiO 2 . Using the conductance method, capacitance-voltage measurements show a decrease in the interface trap density D it of an order of magnitude for oxidized Si substrates with a thicker SiO 2 underlayer. Further reduction of D it was achieved for the capacitors grown on oxidized Si and annealed in forming gas after metallization
Comparison of interfaces for (Ba,Sr)TiO3 films deposited on Si and SiO2/Si substrates

Science.gov (United States)

Suvorova, N. A.; Lopez, C. M.; Irene, E. A.; Suvorova, A. A.; Saunders, M.

2004-03-01

(Ba,Sr)TiO3(BST) thin films were deposited by ion sputtering on both bare and oxidized Si. Spectroscopic ellipsometry results have shown that a SiO2 underlayer of nearly the same thickness (2.6 nm in average) is found at the Si interface for BST sputter depositions onto nominally bare Si, 1 nm SiO2 on Si or 3.5 nm SiO2 on Si. This result was confirmed by high-resolution electron microscopy analysis of the films, and it is believed to be due to simultaneous subcutaneous oxidation of Si and reaction of the BST layer with SiO2. Using the conductance method, capacitance-voltage measurements show a decrease in the interface trap density Dit of an order of magnitude for oxidized Si substrates with a thicker SiO2 underlayer. Further reduction of Dit was achieved for the capacitors grown on oxidized Si and annealed in forming gas after metallization.
Oxidation kinetics of Si and SiGe by dry rapid thermal oxidation, in-situ steam generation oxidation and dry furnace oxidation

Science.gov (United States)

Rozé, Fabien; Gourhant, Olivier; Blanquet, Elisabeth; Bertin, François; Juhel, Marc; Abbate, Francesco; Pribat, Clément; Duru, Romain

2017-06-01

The fabrication of ultrathin compressively strained SiGe-On-Insulator layers by the condensation technique is likely a key milestone towards low-power and high performances FD-SOI logic devices. However, the SiGe condensation technique still requires challenges to be solved for an optimized use in an industrial environment. SiGe oxidation kinetics, upon which the condensation technique is founded, has still not reached a consensus in spite of various studies which gave insights into the matter. This paper aims to bridge the gaps between these studies by covering various oxidation processes relevant to today's technological needs with a new and quantitative analysis methodology. We thus address oxidation kinetics of SiGe with three Ge concentrations (0%, 10%, and 30%) by means of dry rapid thermal oxidation, in-situ steam generation oxidation, and dry furnace oxidation. Oxide thicknesses in the 50 Å to 150 Å range grown with oxidation temperatures between 850 and 1100 °C were targeted. The present work shows first that for all investigated processes, oxidation follows a parabolic regime even for thin oxides, which indicates a diffusion-limited oxidation regime. We also observe that, for all investigated processes, the SiGe oxidation rate is systematically higher than that of Si. The amplitude of the variation of oxidation kinetics of SiGe with respect to Si is found to be strongly dependent on the process type. Second, a new quantitative analysis methodology of oxidation kinetics is introduced. This methodology allows us to highlight the dependence of oxidation kinetics on the Ge concentration at the oxidation interface, which is modulated by the pile-up mechanism. Our results show that the oxidation rate increases with the Ge concentration at the oxidation interface.
Mechanical behavior of SiCf/SiC composites with alternating PyC/SiC multilayer interphases

International Nuclear Information System (INIS)

Yu, Haijiao; Zhou, Xingui; Zhang, Wei; Peng, Huaxin; Zhang, Changrui

2013-01-01

Highlights: ► Superior combination of flexural strength and fracture toughness of the 3D SiC/SiC composite was achieved by interface tailoring. ► Resulted composite possesses a much higher flexural strength and fracture toughness than its counterparts in literatures. ► Mechanisms that PyC/SiC multilayer coatings improve the mechanical properties were illustrated. -- Abstract: In order to tailor the fiber–matrix interface of continuous silicon carbide fiber reinforced silicon carbide (SiC f /SiC) composites for improved fracture toughness, alternating pyrolytic carbon/silicon carbide (PyC/SiC) multilayer coatings were applied to the KD-I SiC fibers using chemical vapor deposition (CVD) method. Three dimensional (3D) KD-I SiC f /SiC composites reinforced by these coated fibers were fabricated using a precursor infiltration and pyrolysis (PIP) process. The interfacial characteristics were determined by the fiber push-out test and microstructural examination using scanning electron microscopy (SEM). The effect of interface coatings on composite mechanical properties was evaluated by single-edge notched beam (SENB) test and three-point bending test. The results indicate that the PyC/SiC multilayer coatings led to an optimum interfacial bonding between fibers and matrix and greatly improved the fracture toughness of the composites.
Oscillations in the fusion of the Si + Si systems

International Nuclear Information System (INIS)

Aguilera R, E.F.; Kolata, J.J.; DeYoung, P.A.; Vega, J.J.

1986-02-01

Excitation functions for the yields of all the residual nuclei from the 28 Si + 28,30 and 30 Si + 30 Si reactions have been measured via the γ-ray technique for center of mass energies in the region within one and two times the Coulomb barrier.Thirteen elements were identified for the first reaction and ten for the other two. While no structure is shown by the data for the 28 + 28 Si reaction, we have found evidence for intermediate width structure in the 2α and the αpn channels in 28 Si + 30 Si and for broad structure in the total fusion cross sections for 30 Si + 30 Si. Calculations using a barrier penetration model with one free parameter reproduce the experimental results quite well. Evaporation model calculations indicate that the individual structure of the nuclei involved in the respective decay chains might have an important influence upon the deexcitation process at the energies relevant to our experiments. (Author)

Highly stable carbon-doped Cu films on barrierless Si

International Nuclear Information System (INIS)

Zhang, X.Y.; Li, X.N.; Nie, L.F.; Chu, J.P.; Wang, Q.; Lin, C.H.; Dong, C.

2011-01-01

Electrical resistivities and thermal stabilities of carbon-doped Cu films on silicon have been investigated. The films were prepared by magnetron sputtering using a Cu-C alloy target. After annealing at 400 deg. C for 1 h, the resistivity maintains a low level at 2.7 μΩ-cm and no Cu-Si reaction is detected in the film by X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations. According to the secondary ion mass spectroscopy (SIMS) results, carbon is enriched near the interfacial region of Cu(C)/Si, and is considered responsible for the growth of an amorphous Cu(C)/Si interlayer that inhibits the Cu-Si inter-diffusion. Fine Cu grains, less than 100 nm, were present in the Cu(C) films after long-term and high-temperature annealings. The effect of C shows a combination of forming a self-passivated interface barrier layer and maintaining a fine-grained structure of Cu. A low current leakage measured on this Cu(C) film also provides further evidence for the carbon-induced diffusion barrier interlayer performance.
Atomistic simulations of the effect of embedded hydrogen and helium on the tensile properties of monocrystalline and nanocrystalline tungsten

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhe [Department of Physics, Beihang University, Beijing 100191 (China); Department of Mechanical Engineering, University of North Carolina at Charlotte, Charlotte, NC 28223-0001 (United States); Kecskes, Laszlo J. [US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, MD 21005 (United States); Zhu, Kaigui, E-mail: kgzhu@buaa.edu.cn [Department of Physics, Beihang University, Beijing 100191 (China); Beijing Key Laboratory of Advanced Nuclear Energy Materials and Physics, Beihang University, Beijing 100191 (China); Wei, Qiuming, E-mail: qwei@uncc.edu [Department of Mechanical Engineering, University of North Carolina at Charlotte, Charlotte, NC 28223-0001 (United States)

2016-12-01

Uniaxial tensile properties of monocrystalline tungsten (MC-W) and nanocrystalline tungsten (NC-W) with embedded hydrogen and helium atoms have been investigated using molecular dynamics (MD) simulations in the context of radiation damage evolution. Different strain rates have been imposed to investigate the strain rate sensitivity (SRS) of the samples. Results show that the plastic deformation processes of MC-W and NC-W are dominated by different mechanisms, namely dislocation-based for MC-W and grain boundary-based activities for NC-W, respectively. For MC-W, the SRS increases and a transition appears in the deformation mechanism with increasing embedded atom concentration. However, no obvious embedded atom concentration dependence of the SRS has been observed for NC-W. Instead, in the latter case, the embedded atoms facilitate GB sliding and intergranular fracture. Additionally, a strong strain enhanced He cluster growth has been observed. The corresponding underlying mechanisms are discussed. - Highlights: • Uniaxial tensile behavior of monocrystal tungsten (C-W) and nanocrystalline W (NC-W) have been investigated. • Dislocation-based activities dominate the plastic deformation of MC-W. • Grain boundary-based activities dominate the plastic deformation of NC-W. • H/He atoms have significant impacts on the tensile behavior of MC-W and NC-W. • Strong strain enhanced He cluster growth has been revealed.
Complex dewetting scenarios of ultrathin silicon films for large-scale nanoarchitectures.

Science.gov (United States)

Naffouti, Meher; Backofen, Rainer; Salvalaglio, Marco; Bottein, Thomas; Lodari, Mario; Voigt, Axel; David, Thomas; Benkouider, Abdelmalek; Fraj, Ibtissem; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle; Grosso, David; Abbarchi, Marco; Bollani, Monica

2017-11-01

Dewetting is a ubiquitous phenomenon in nature; many different thin films of organic and inorganic substances (such as liquids, polymers, metals, and semiconductors) share this shape instability driven by surface tension and mass transport. Via templated solid-state dewetting, we frame complex nanoarchitectures of monocrystalline silicon on insulator with unprecedented precision and reproducibility over large scales. Phase-field simulations reveal the dominant role of surface diffusion as a driving force for dewetting and provide a predictive tool to further engineer this hybrid top-down/bottom-up self-assembly method. Our results demonstrate that patches of thin monocrystalline films of metals and semiconductors share the same dewetting dynamics. We also prove the potential of our method by fabricating nanotransfer molding of metal oxide xerogels on silicon and glass substrates. This method allows the novel possibility of transferring these Si-based patterns on different materials, which do not usually undergo dewetting, offering great potential also for microfluidic or sensing applications.
Structure of MnSi on SiC(0001)

Science.gov (United States)

Meynell, S. A.; Spitzig, A.; Edwards, B.; Robertson, M. D.; Kalliecharan, D.; Kreplak, L.; Monchesky, T. L.

2016-11-01

We report on the growth and magnetoresistance of MnSi films grown on SiC(0001) by molecular beam epitaxy. The growth resulted in a textured MnSi(111) film with a predominantly [1 1 ¯0 ] MnSi (111 )∥[11 2 ¯0 ] SiC(0001) epitaxial relationship, as demonstrated by transmission electron microscopy, reflection high energy electron diffraction, and atomic force microscopy. The 500 ∘C temperature required to crystallize the film leads to a dewetting of the MnSi layer. Although the sign of the lattice mismatch suggested the films would be under compressive stress, the films acquire an in-plane tensile strain likely driven by the difference in thermal expansion coefficients between the film and substrate during annealing. As a result, the magnetoresistive response demonstrates that the films possess a hard-axis out-of-plane magnetocrystalline anisotropy.
Naturally occurring 32 Si and low-background silicon dark matter detectors

Energy Technology Data Exchange (ETDEWEB)

Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

2018-05-01

The naturally occurring radioisotope Si-32 represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of Si-32 and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the Si-32 concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon “ore” and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of Si-32-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in Si-32. To quantitatively evaluate the Si-32 content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon-based detectors with low levels of Si-32, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.
Naturally occurring 32Si and low-background silicon dark matter detectors

Science.gov (United States)

Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

2018-05-01

The naturally occurring radioisotope 32Si represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of 32Si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the 32Si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon "ore" and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of 32Si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32Si. To quantitatively evaluate the 32Si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon detectors with low levels of 32Si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.
Preparation and study of nanostructured TiAlSiN thin films

Directory of Open Access Journals (Sweden)

Jakab-Farkas L.

2011-12-01

Full Text Available TiAlSiN thin film coatings were deposited by DC reactive magnetron sputtering of TiAlSi target with 40 at.% Ti, 40 at.% Al and 20 at.% Si, performed in N2-Ar gas mixture. The sputtering power used in these experiments was controlled for 400 W. The bias voltage of the substrates was kept at -20 V DC and the temperature at 500 0C. All the samples were prepared with a constant flow rate of Ar and different nitrogen flow rates, which were selected from 1.25 sccm to 4.0 sccm. Nanostructured TiAlSiN coatings were developed on Si(100 and HSS substrates. Microstructure investigation of the coatings was performed by transmission electron microscopy investigation, structure investigation was performed by XRD analysis, and the mechanical properties of the coatings have been tested by ball-on-disk tribological investigation and micro-Vickers hardness measurements. In this paper will be shown that for optimized nitrogen concentration the microstructure of TiAlSiN coating evolve from a competitive columnar growth to a dendritic growth one with very fine nano-lamellae like morphology. The developed nanostructured TiAlSiN coatingshave hardness HV exceeding 40 GPa and show an increased abrasive wear resistance
Laser-controlled stress of Si nanocrystals in a free-standing Si /SiO2 superlattice

Science.gov (United States)

Khriachtchev, Leonid; Räsänen, Markku; Novikov, Sergei

2006-01-01

We report laser manipulations with stress at the nanoscale level. The continuous-wave Ar+ laser radiation melts Si nanocrystals in a free-standing Si /SiO2 superlattice. Silicon crystallization from the liquid phase leads to a compressive stress, which can be accurately tuned in the 3GPa range using laser annealing below the Si melting temperature and then recovered by laser annealing above the melting temperature. This allows investigations of various phenomena as a function of stress and makes a case of Si-nanocrystal memory with very long retention time, which can be written, erased, and read by optical means.
Laser-controlled stress of Si nanocrystals in a free-standing Si/SiO2 superlattice

International Nuclear Information System (INIS)

Khriachtchev, Leonid; Raesaenen, Markku; Novikov, Sergei

2006-01-01

We report laser manipulations with stress at the nanoscale level. The continuous-wave Ar + laser radiation melts Si nanocrystals in a free-standing Si/SiO 2 superlattice. Silicon crystallization from the liquid phase leads to a compressive stress, which can be accurately tuned in the 3 GPa range using laser annealing below the Si melting temperature and then recovered by laser annealing above the melting temperature. This allows investigations of various phenomena as a function of stress and makes a case of Si-nanocrystal memory with very long retention time, which can be written, erased, and read by optical means
Structure and wear behavior of AlCrSiN-based coatings

Energy Technology Data Exchange (ETDEWEB)

Chen, Yun [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Du, Hao [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Ming, E-mail: mchen@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Jun [Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Xiong, Ji [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhao, Haibo [The Analysis and Testing Centre, Sichuan University, Chengdu 610065 (China)

2016-05-01

Graphical abstract: - Highlights: • AlCrSiN based coating showed amorphous structure. • AlCrSiN/Me{sub x}N coatings obtained better wear resistance. • Molybdenum and niobium increased the coating hardness and wear resistance. - Abstract: AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC–Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N{sub 2} mixtures. Al{sub 0.6}Cr{sub 0.4}, Al{sub 0.6}Cr{sub 0.3}Si{sub 0.1}, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiN{sub x} peak were formed in the AlCrSiN/Me{sub x}N coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H{sup 3}/E{sup 2} ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.
Biocompatible and colloidally stabilized mPEG-PE/calcium phosphate hybrid nanoparticles loaded with siRNAs targeting tumors

OpenAIRE

Gao, Pei; Zhang, Xiangyu; Wang, Hongzhi; Zhang, Qinghong; Li, He; Li, Yaogang; Duan, Yourong

2015-01-01

Calcium phosphate nanoparticles are safe and effective delivery vehicles for small interfering RNA (siRNA), as a result of their excellent biocompatibility. In this work, mPEG-PE (polyethylene glycol-L-?-phosphatidylethanolamine) was synthesized and used to prepare nanoparticles composed of mPEG-PE and calcium phosphate for siRNA delivery. Calcium phosphate and mPEG-PE formed the stable hybrid nanoparticles through self-assembly resulting from electrostatic interaction in water. The average s...
Self-aligned indium–gallium–zinc oxide thin-film transistors with SiNx/SiO2/SiNx/SiO2 passivation layers

International Nuclear Information System (INIS)

Chen, Rongsheng; Zhou, Wei; Zhang, Meng; Kwok, Hoi-Sing

2014-01-01

Self-aligned top-gate amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) with SiN x /SiO 2 /SiN x /SiO 2 passivation layers are developed in this paper. The resulting a-IGZO TFT exhibits high reliability against bias stress and good electrical performance including field-effect mobility of 5 cm 2 /Vs, threshold voltage of 2.5 V, subthreshold swing of 0.63 V/decade, and on/off current ratio of 5 × 10 6 . With scaling down of the channel length, good characteristics are also obtained with a small shift of the threshold voltage and no degradation of subthreshold swing. The proposed a-IGZO TFTs in this paper can act as driving devices in the next generation flat panel displays. - Highlights: • Self-aligned top-gate indium–gallium–zinc oxide thin-film transistor is proposed. • SiN x /SiO 2 /SiN x /SiO 2 passivation layers are developed. • The source/drain areas are hydrogen-doped by CHF3 plasma. • The devices show good electrical performance and high reliability against bias stress
Efficient in vitro delivery of Noggin siRNA enhances osteoblastogenesis

Directory of Open Access Journals (Sweden)

S. Ghadakzadeh

2017-11-01

Full Text Available Several types of serious bone defects would not heal without invasive clinical intervention. One approach to such defects is to enhance the capacity of bone-formation cells. Exogenous bone morphogenetic proteins (BMP have been utilized to positively regulate matrix mineralization and osteoblastogenesis, however, numerous adverse effects are associated with this approach. Noggin, a potent antagonist of BMPs, is an ideal candidate to target and decrease the need for supraphysiological doses of BMPs. In the current research we report a novel siRNA-mediated gene knock-down strategy to down-regulate Noggin. We utilized a lipid nanoparticle (LNP delivery strategy in pre-osteoblastic rat cells. In vitro LNP-siRNA treatment caused inconsequential cell toxicity and transfection was achieved in over 85% of cells. Noggin siRNA treatment successfully down-regulated cellular Noggin protein levels and enhanced BMP signal activity which in turn resulted in significantly increased osteoblast differentiation and extracellular matrix mineralization evidenced by histological assessments. Gene expression analysis showed that targeting Noggin specifically in bone cells would not lead to a compensatory effect from other BMP negative regulators such as Gremlin and Chordin. The results from this study support the notion that novel therapeutics targeting Noggin have the clinically relevant potential to enhance bone formation without the need for toxic doses of exogenous BMPs. Such treatments will undeniably provide safe and economical treatments for individuals whose poor bone repair results in permanent morbidity and disability. Keywords: Biological sciences, Biomedical engineering, Bioengineering, Biotechnology, Cell biology, Genetics
Synthesis and characterization of laminated Si/SiC composites

Science.gov (United States)

Naga, Salma M.; Kenawy, Sayed H.; Awaad, Mohamed; Abd El-Wahab, Hamada S.; Greil, Peter; Abadir, Magdi F.

2012-01-01

Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results. PMID:25685404
Synthesis and characterization of laminated Si/SiC composites

Directory of Open Access Journals (Sweden)

Salma M. Naga

2013-01-01

Full Text Available Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.
Propagation of misfit dislocations from buffer/Si interface into Si

Science.gov (United States)

Liliental-Weber, Zuzanna [El Sobrante, CA; Maltez, Rogerio Luis [Porto Alegre, BR; Morkoc, Hadis [Richmond, VA; Xie, Jinqiao [Raleigh, VA

2011-08-30

Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.
Tailoring of SiC nanoprecipitates formed in Si

Energy Technology Data Exchange (ETDEWEB)

Velisa, G., E-mail: gihan.velisa@cea.fr [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Magurele (Romania); Trocellier, P. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Thomé, L. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Vaubaillon, S. [CEA, INSTN, UEPTN, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Miro, S.; Serruys, Y.; Bordas, É. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Meslin, E. [CEA, DEN, Service de Recherches de Métallurgie Physique, F-91191 Gif-sur-Yvette (France); Mylonas, S. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Coulon, P.E. [Ecole Polytechnique, Laboratoire des Solides Irradiés, CEA/DSM/IRAMIS-CNRS, 91128 Palaiseau Cedex (France); Leprêtre, F.; Pilz, A.; Beck, L. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France)

2013-07-15

The SiC synthesis through single-beam of C{sup +}, and simultaneous-dual-beam of C{sup +} and Si{sup +} ion implantations into a Si substrate heated at 550 °C has been studied by means of three complementary analytical techniques: nuclear reaction analysis (NRA), Raman, and transmission electron microscopy (TEM). It is shown that a broad distribution of SiC nanoprecipitates is directly formed after simultaneous-dual-beam (520-keV C{sup +} and 890-keV Si{sup +}) and single-beam (520-keV C{sup +}) ion implantations. Their shape appear as spherical (average size ∼4–5 nm) and they are in epitaxial relationship with the silicon matrix.
Uniform Si nano-dot fabrication using reconstructed structure of Si(110)

Science.gov (United States)

Yano, Masahiro; Uozumi, Yuki; Yasuda, Satoshi; Asaoka, Hidehito

2018-06-01

Si nano-dot (ND) formation on Si(110) is observed by means of a scanning tunneling microscope (STM). The initial Si-NDs are Si crystals that are continuous from the substrate and grow during the oxide layer desorption. The NDs fabricated on the flat surface of Si(110)-1 × 1 are surrounded by four types of facets with almost identical appearance probabilities. An increase in the size of the NDs increases the variety of its morphology. In contrast, most Si-NDs fabricated on straight-stepped surface of Si(110)-16 × 2 reconstructed structure are surrounded by only a single type of facet, namely the \\text{Si}(17,15,1)-2 × 1 plane. An appearance probability of the facet in which the base line is along the step of Si(110)-16 × 2 exceeds 75%. This finding provides a fabrication technique of uniformed structural Si-NDs by using the reconstructed structure of Si(110).
Neutron tolerance of advanced SiC-fiber/CVI-SiC composites

International Nuclear Information System (INIS)

Katoh, Y.; Kohyama, A.; Snead, L.L.; Hinoki, T.; Hasegawa, A.

2003-01-01

Fusion blankets employing a silicon carbide (SiC) fiber-reinforced SiC matrix composite (SiC/SiC composite) as the structural material provide attractive features represented by high cycle efficiency and extremely low induced radioactivity. Recent advancement in processing and utilization techniques and application studies in ceramic gas turbine and advanced transportation systems, SiC/SiC composites are steadily getting matured as industrial materials. Reference SiC/SiC composites for fusion structural applications have been produced by a forced-flow chemical vapor infiltration (FCVI) method using conventional and advanced near-stoichiometric SiC fibers and extensively evaluated primarily in Japan-US collaborative JUPITER program. In this work, effect of neutron irradiation at elevated temperatures on mechanical property of these composites is characterized. Unlike in conventional SiC/SiC composites, practically no property degradation was identified in advanced composites with a thin carbon interphase by a neutron fluence level of approximately 8dpa at 800C. (author)
High thermal conductivity SiC/SiC composites for fusion applications -- 2

International Nuclear Information System (INIS)

Kowbel, W.; Tsou, K.T.; Withers, J.C.; Youngblood, G.E.

1998-01-01

This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion Structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. An unirradiated SiC/SiC composite made with MER-developed CVR SiC fiber and a hybrid PIP/CVI SiC matrix exhibited room temperature transverse thermal conductivity of 45 W/mK. An unirradiated SiC/SiC composite made from C/C composite totally CVR-converted to a SiC/SiC composite exhibited transverse thermal conductivity values of 75 and 35 W/mK at 25 and 1000 C, respectively. Both types of SiC/SiC composites exhibited non-brittle failure in flexure testing

Systematic continuum-discretized coupled-channels calculations of total fusion for 6Li with targets 28Si, 59Co, 96Zr, 198Pt, and 209Bi: Effect of resonance states

Science.gov (United States)

Gómez Camacho, A.; Wang, Bing; Zhang, H. Q.

2018-05-01

Continuum discretized coupled-channel (CDCC) calculations of total fusion cross sections for reactions induced by the weakly bound nucleus 6Li with targets 28Si, 59Co, 96Zr, 198Pt, and 209Bi at energies around the Coulomb barrier are presented. In the cluster structure frame of 6Li→α +d , short-range absorption potentials are considered for the interactions between the α and d fragments with the targets. The effect of resonance (l =2 , Jπ=3+,2+,1+ ) and nonresonance states of 6Li on fusion is studied by using two approaches: (1) by omitting the resonance states from the full discretized CDCC breakup space and (2) by considering only the resonance subspace. A systematic analysis of the effect on fusion from resonance breakup couplings is carried out from light to heavy mass targets. Among other things, it is found that resonance breakup states produce strong repulsive polarization potentials that lead to fusion suppression. Couplings from nonresonance states give place to weak repulsive potentials at high energies; however, these become attractive for the heavier targets at low energies.
Passivation of defect states in Si and Si/SiO2 interface states by cyanide treatment: improvement of characteristics of pin-junction amorphous Si and crystalline Si-based metal-oxide-semiconductor junction solar cells

International Nuclear Information System (INIS)

Fujiwara, N.; Fujinaga, T.; Niinobe, D.; Maida, O.; Takahashi, M.; Kobayashi, H.

2003-01-01

Defect states in Si can be passivated by cyanide treatment which simply involves immersion of Si materials in KCN solutions, followed by rinse. When the cyanide treatment is applied to pin-junction amorphous Si [a-Si] solar cells, the initial conversion efficiency increases. When the crown-ether cyanide treatment using a KCN solution of xylene containing 18-crown-6 is performed on i-a-Si films, decreases in the photo- and dark current densities with the irradiation time are prevented. The cyanide treatment can also passivate interface states present at Si/SiO 2 interfaces, leading to an increase in the conversion efficiency of 2 / Si (100)> solar cells.. Si-CN bonds formed by the reaction of defect states with cyanide ions have a high bond energy of about 4.5 eV and hence heat treatment at 800 0 C does not rupture the bonds, making thermal stability of the cyanide treatment.. When the cyanide treatment is applied to ultrathin SiO 2 /Si structure, the leakage current density is markedly decreased (Authors)
Monocrystalline silicon photovoltaic luminescent solar concentrator with 4.2% power conversion efficiency

NARCIS (Netherlands)

Desmet, L.; Ras, A.J.M.; Boer, de D.K.G.; Debije, M.G.

2012-01-01

We report conversion efficiencies of experimental single and dual light guide luminescent solar concentrators. We have built several 5¿¿cm×5¿¿cm and 10¿¿cm×10¿¿cm luminescent solar concentrator (LSC) demonstrators consisting of c-Si photovoltaic cells attached to luminescent light guides of Lumogen
Nanoparticle-neural stem cells for targeted ovarian cancer treatment: optimization of silica nanoparticles for efficient drug loading

Science.gov (United States)

Patel, Z.; Berlin, J.; Abidi, W.

2018-02-01

One of the drugs used to treat ovarian cancer is cisplatin. However, cisplatin kills normal surrounding tissue in addition to cancer cells. To improve tumor targeting efficiency, our lab uses neural stem cells (NSCs), which migrate directly to ovarian tumors. If free cisplatin is loaded into NSCs for targeted drug delivery, it will kill the NSCs. To prevent the drug cisplatin from killing both the NSCs and normal surrounding tissue, our lab synthesizes silica nanoparticles (SiNPs) that act as a protective carrier. The big picture here is to maximize efficiency of tumor targeting using NSCs and minimize toxicity to these NSCs using SiNPs. The goal of this project is to optimize the stability of SiNPs, which is important for efficient drug loading. To do this, the concentration of tetraethyl orthosilicate (TEOS), one of the main components of SiNPs, was varied. We hypothesized that more TEOS equates to more stable SiNPs because TEOS contributes carbon to SiNPs, and thus a tightly-packed chemical structure results in a stable particle. Then, the stability of the SiNPs were checked in cell media and phosphate buffered saline (PBS). Lastly, the SiNPs were analyzed for their porosity using the transmission electron microscope (TEM). TEM imaging showed white spots in the 200-800 μL TEOS batches and no white spots in the 1000-1800 μL TEOS batches. The white spots were pores, which indicate instability. We concluded that the ultimate factor that determines the stability of SiNPs (100 nm) is the concentration of organic substance.
The dependence of the interface and shape on the constrained growth of nc-Si in a-SiN sub x /a-Si:H/a-SiN sub x structures

CERN Document Server

Zhang Li; Wang Li; Li Wei; Xu Jun; Huang Xin Fan; Chen Kun Ji

2002-01-01

Size-controlled nanocrystalline silicon (nc-Si) has been prepared from a-SiN sub x /a-Si:H/a-SiN sub x ('a' standing for amorphous) structures by thermal annealing. Transmission electron microscope analyses show that the lateral size of the nc-Si is controlled by the annealing conditions and the a-Si sublayer thickness. The deviation of the nc-Si grain size distribution decreases with the a-Si sublayer thickness, so thinner a-Si sublayers are favourable for obtaining uniform nc-Si grains. In the a-Si:H (10 nm) sample annealed at 1000 deg. C for 30 min, an obvious bi-modal size distribution of nc-Si grains appears, but no obvious bi-modal size distribution is found in other samples with thinner a-Si:H sublayers. On the basis of the experimental results, we discuss the process of transition from the sphere-like shape to the disc-like shape in the growth model of the nc-Si crystallization. The critical thickness of the a-Si sublayer for the constrained crystallization can be determined by the present model. More...
Gas leak tightness of SiC/SiC composites at elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Hayasaka, Daisuke, E-mail: hayasaka@oasis.muroran-it.ac.jp [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Park, Joon-Soo. [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan)

2016-11-01

Highlights: • NITE-SiC/SiC has extremely densified microstructure compared with other SiC/SiC composite like CVI. • Excellent helium and hydrogen gas-leak tightness of SiC/SiC composites by DEMO-NITE method from prototype industrialization production line was presented. • The excellence against stainless steel and Zircaloy at elevated temperature, together with generic excellent properties of SiC will be inevitable for innovative blanket and divertors for DEMO- and power- fusion reactors. - Abstract: SiC/SiC composite materials are attractive candidates for high heat flux components and blanket of fusion reactor, mainly due to their high temperature properties, radiation damage tolerance and low induced radioactivity. One of the challenges for SiC/SiC application in fusion reactors is to satisfy sufficient gas leak tightness of hydrogen and helium isotopes. Although many efforts have been carried-out, SiC/SiC composites by conventional processes have not been successful to satisfy the requirements, except SiC/SiC composites by NITE-methods. Toward the early realization of SiC/SiC components into fusion reactor systems process development of NITE-process has been continued. Followed to the brief introduction of recently developed DEMO-NITE process, baseline properties and hydrogen and helium gas leak tightness is presented. SiC/SiC claddings with 10 mm in diameter and 1 mm in wall thickness are tested by gas leak tightness system developed. The leak tightness measurements are done room temperature to 400 °C. Excellent gas leak tightness equivalent or superior to Zircaloy claddings for light water fission reactors is confirmed. The excellent gas leak tightness suggests nearly perfect suppression of large gas leak path in DEMO-NITE SiC/SiC.
Advanced Optoelectronic Devices based on Si Quantum Dots/Si Nanowires Hetero-structures

International Nuclear Information System (INIS)

Xu, J; Zhai, Y Y; Cao, Y Q; Chen, K J

2017-01-01

Si quantum dots are currently extensively studied since they can be used to develop many kinds of optoelectronic devices. In this report, we review the fabrication of Si quantum dots (Si QD) /Si nanowires (Si NWs) hetero-structures by deposition of Si QDs/SiO 2 or Si QDs/SiC multilayers on Si NWs arrays. The electroluminescence and photovoltaic devices based on the formed hetero-structures have been prepared and the improved performance is confirmed. It is also found that the surface recombination via the surface defects states on the Si NWs, especially the ones obtained by the long-time etching, may deteriorate the device properties though they exhibit the better anti-reflection characteristics. The possible surface passivation approaches are briefly discussed. (paper)
Study of atomic excitations in sputtering with targets partially covered with oxygen

International Nuclear Information System (INIS)

Weng, J.; Veje, E.

1984-01-01

We have bombarded pure, elemental targets of Be, B, Mg, Al, Si, Ti, and Au with 80 keV Ar + ions and studied excitation of sputtered atoms or ions under UHV conditions as well as with oxygen present at the target surface. The measurements on Mg, Al, Si, and Ti have been done at projectile incidence angles from 0 0 to 85 0 . Excitation probabilities for gold were found to be only very little influenced by oxygen, but for Be, B, Mg, Al, Si, and Ti, the excitation probabilities were in many, but not all, cases found to depend strongly on the oxygen pressure as well as on the beam current density. This indicates that the excitation mechanism is strongly dependent on the initial electronic conditions of the solid. (orig.)
A genome-wide siRNA screen to identify modulators of insulin sensitivity and gluconeogenesis.

Directory of Open Access Journals (Sweden)

Ruojing Yang

Full Text Available BACKGROUND: Hepatic insulin resistance impairs insulin's ability to suppress hepatic glucose production (HGP and contributes to the development of type 2 diabetes (T2D. Although the interests to discover novel genes that modulate insulin sensitivity and HGP are high, it remains challenging to have a human cell based system to identify novel genes. METHODOLOGY/PRINCIPAL FINDINGS: To identify genes that modulate hepatic insulin signaling and HGP, we generated a human cell line stably expressing beta-lactamase under the control of the human glucose-6-phosphatase (G6PC promoter (AH-G6PC cells. Both beta-lactamase activity and endogenous G6PC mRNA were increased in AH-G6PC cells by a combination of dexamethasone and pCPT-cAMP, and reduced by insulin. A 4-gene High-Throughput-Genomics assay was developed to concomitantly measure G6PC and pyruvate-dehydrogenase-kinase-4 (PDK4 mRNA levels. Using this assay, we screened an siRNA library containing pooled siRNA targeting 6650 druggable genes and identified 614 hits that lowered G6PC expression without increasing PDK4 mRNA levels. Pathway analysis indicated that siRNA-mediated knockdown (KD of genes known to positively or negatively affect insulin signaling increased or decreased G6PC mRNA expression, respectively, thus validating our screening platform. A subset of 270 primary screen hits was selected and 149 hits were confirmed by target gene KD by pooled siRNA and 7 single siRNA for each gene to reduce G6PC expression in 4-gene HTG assay. Subsequently, pooled siRNA KD of 113 genes decreased PEPCK and/or PGC1alpha mRNA expression thereby demonstrating their role in regulating key gluconeogenic genes in addition to G6PC. Last, KD of 61 of the above 113 genes potentiated insulin-stimulated Akt phosphorylation, suggesting that they suppress gluconeogenic gene by enhancing insulin signaling. CONCLUSIONS/SIGNIFICANCE: These results support the proposition that the proteins encoded by the genes identified in
Facile synthesis of highly biocompatible folic acid-functionalised SiO2 nanoparticles encapsulating rare-earth metal complexes, and their application in targeted drug delivery.

Science.gov (United States)

Xu, Xiuling; Hu, Fan; Shuai, Qi

2017-11-14

Mesoporous silica core-shell nanospheres encapsulating a rare-earth metal complex (RC) were first synthesised through a facile W/O (water in oil) inverse microemulsion method. In order to achieve targeted complex delivery, folic acid (FA) was used as the targeting component due to its high affinity for over-expressed folate receptors (FRs) in cancer cells. The RC 2 @SiO 2 -FA nanospheres were characterised via ultraviolet-visible light absorption spectroscopy (UV-vis spectroscopy), dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A microwave method was used to synthesise five RC cores based on 4-chlorophenoxyacetic acid, and their crystal structures were further confirmed using X-ray diffraction. The five RC cores have the following chemical formulae: [Er 2 (p-CPA) 6 (H 2 O) 6 ] RC 1 , [Ho 2 (p-CPA) 6 (H 2 O) 6 ] RC 2 , [Sm(p-CPA) 3 (H 2 O)] RC 3 , [Pr(p-CPA) 3 (H 2 O)]·3H 2 O RC 4 and [Ce(p-CPA) 3 (H 2 O) 2 ]·2H 2 O RC 5 . The carboxyl groups showed two kinds of coordination modes, namely μ 2 -η 1 :η 1 and μ 2 -η 1 :η 2 , among RC 1 -RC 5 . The flexible -OCH 2 COO- spacer group, which can undergo rotation of its C-O and C-C bonds, offered great potential for structural diversity. In vivo experiments revealed that the nanospheres exhibited no obvious cytotoxicity on HepG2 cells and 293 T cells, even at concentrations of up to 80 μg mL -1 . Nevertheless, all of the RC cores showed a certain degree of anti-tumour efficacy; in particular, RC 2 showed the strongest cytotoxicity against HepG2 cells. Interestingly, the cytotoxicity of all of the RC 2 @SiO 2 -FA nanospheres was higher than that of lone RC 2 . These types of FA-targeted mesoporous silica nanocarriers can be used for the delivery of anti-tumour RC, and provide a basis for the further study of affordable non-platinum-based complexes.
Investigation of thin oxide layer removal from Si substrates using an SiO2 atomic layer etching approach: the importance of the reactivity of the substrate

International Nuclear Information System (INIS)

Metzler, Dominik; Oehrlein, Gottlieb S; Li, Chen; Lai, C Steven; Hudson, Eric A

2017-01-01

The evaluation of a plasma-based atomic layer etching (ALE) approach for native oxide surface removal from Si substrates is described. Objectives include removal of the native oxide while minimizing substrate damage, surface residues and substrate loss. Oxide thicknesses were measured using in situ ellipsometry and surface chemistry was analyzed by x-ray photoelectron spectroscopy. The cyclic ALE approach when used for removal of native oxide SiO 2 from a Si substrate did not remove native oxide to the extent required. This is due to the high reactivity of the silicon substrate during the low-energy (<40 eV) ion bombardment phase of the cyclic ALE approach which leads to reoxidation of the silicon surface. A modified process, which used continuously biased Ar plasma with periodic CF 4 injection, achieved significant oxygen removal from the Si surface, with some residual carbon and fluorine. A subsequent H 2 /Ar plasma exposure successfully removed residual carbon and fluorine while passivating the silicon surface. The combined treatment reduced oxygen and carbon levels to about half compared to as received silicon surfaces. The downside of this process sequence is a net loss of about 40 Å of Si. A generic insight of this work is the importance of the substrate and final surface chemistry in addition to precise etch control of the target film for ALE processes. By a fluorocarbon-based ALE technique, thin SiO 2 layer removal at the Ångstrom level can be precisely performed from an inert substrate, e.g. a thick SiO 2 layer. However, from a reactive substrate, like Si, complete removal of the thin SiO 2 layer is prevented by the high reactivity of low energy Ar + ion bombarded Si. The Si surfaces are reoxidized during the ALE ion bombardment etch step, even for very clean and ultra-low O 2 process conditions. (paper)
Low-temperature magnetotransport in Si/SiGe heterostructures on 300 mm Si wafers

Science.gov (United States)

Scappucci, Giordano; Yeoh, L.; Sabbagh, D.; Sammak, A.; Boter, J.; Droulers, G.; Kalhor, N.; Brousse, D.; Veldhorst, M.; Vandersypen, L. M. K.; Thomas, N.; Roberts, J.; Pillarisetty, R.; Amin, P.; George, H. C.; Singh, K. J.; Clarke, J. S.

Undoped Si/SiGe heterostructures are a promising material stack for the development of spin qubits in silicon. To deploy a qubit into high volume manufacturing in a quantum computer requires stringent control over substrate uniformity and quality. Electron mobility and valley splitting are two key electrical metrics of substrate quality relevant for qubits. Here we present low-temperature magnetotransport measurements of strained Si quantum wells with mobilities in excess of 100000 cm2/Vs fabricated on 300 mm wafers within the framework of advanced semiconductor manufacturing. These results are benchmarked against the results obtained in Si quantum wells deposited on 100 mm Si wafers in an academic research environment. To ensure rapid progress in quantum wells quality we have implemented fast feedback loops from materials growth, to heterostructure FET fabrication, and low temperature characterisation. On this topic we will present recent progress in developing a cryogenic platform for high-throughput magnetotransport measurements.
A framework for multiple kernel support vector regression and its applications to siRNA efficacy prediction.

Science.gov (United States)

Qiu, Shibin; Lane, Terran

2009-01-01

The cell defense mechanism of RNA interference has applications in gene function analysis and promising potentials in human disease therapy. To effectively silence a target gene, it is desirable to select appropriate initiator siRNA molecules having satisfactory silencing capabilities. Computational prediction for silencing efficacy of siRNAs can assist this screening process before using them in biological experiments. String kernel functions, which operate directly on the string objects representing siRNAs and target mRNAs, have been applied to support vector regression for the prediction and improved accuracy over numerical kernels in multidimensional vector spaces constructed from descriptors of siRNA design rules. To fully utilize information provided by string and numerical data, we propose to unify the two in a kernel feature space by devising a multiple kernel regression framework where a linear combination of the kernels is used. We formulate the multiple kernel learning into a quadratically constrained quadratic programming (QCQP) problem, which although yields global optimal solution, is computationally demanding and requires a commercial solver package. We further propose three heuristics based on the principle of kernel-target alignment and predictive accuracy. Empirical results demonstrate that multiple kernel regression can improve accuracy, decrease model complexity by reducing the number of support vectors, and speed up computational performance dramatically. In addition, multiple kernel regression evaluates the importance of constituent kernels, which for the siRNA efficacy prediction problem, compares the relative significance of the design rules. Finally, we give insights into the multiple kernel regression mechanism and point out possible extensions.
Si-to-Si wafer bonding using evaporated glass

DEFF Research Database (Denmark)

Reus, Roger De; Lindahl, M.

1997-01-01

Anodic bonding of Si to Si four inch wafers using evaporated glass was performed in air at temperatures ranging from 300°C to 450°C. Although annealing of Si/glass structures around 340°C for 15 minutes eliminates stress, the bonded wafer pairs exhibit compressive stress. Pull testing revealed...
Centrifugally cast Zn-27Al-xMg-ySi alloys and their in situ (Mg2Si + Si)/ZA27 composites

International Nuclear Information System (INIS)

Wang Qudong; Chen Yongjun; Chen Wenzhou; Wei Yinhong; Zhai Chunquan; Ding Wenjiang

2005-01-01

Effects of composition, mold temperature, rotating rate and modification on microstructure of centrifugally cast Zn-27Al-xMg-ySi alloys have been investigated. In situ composites of Zn-27Al-6.3Mg-3.7Si and Zn-27Al-9.8Mg-5.2Si alloys were fabricated by centrifugal casting using heated permanent mold. These composites consist of three layers: inner layer segregates lots of blocky primary Mg 2 Si and a litter blocky primary Si, middle layer contains without primary Mg 2 Si and primary Si, outer layer contains primary Mg 2 Si and primary Si. The position, quantity and distribution of primary Mg 2 Si and primary Si in the composites are determined jointly by alloy composition, solidification velocity under the effect of centrifugal force and their floating velocity inward. Na salt modifier can refine grain and primary Mg 2 Si and make primary Mg 2 Si distribute more evenly and make primary Si nodular. For centrifugally cast Zn-27Al-3.2Mg-1.8Si alloy, the microstructures of inner layer, middle layer and outer layer are almost similar, single layer materials without primary Mg 2 Si and primary Si are obtained, and their grain sizes increased with the mold temperature increasing
Development of SiC/SiC composite for fusion application

International Nuclear Information System (INIS)

Kohyama, A.; Katoh, Y.; Snead, L.L.; Jones, R.H.

2001-01-01

The recent efforts to develop SiC/SiC composite materials for fusion application under the collaboration with Japan and the USA are provided, where material performance with and without radiation damage has been greatly improved. One of the accomplishments is development of the high performance reaction sintering process. Mechanical and thermal conductivity are improved extensively by process modification and optimization with inexpensive fabrication process. The major efforts to make SiC matrix by CVI, PIP and RS methods are introduced together with the representing baseline properties. The resent results on mechanical properties of SiC/SiC under neutron irradiation are quite positive. The composites with new SiC fibers, Hi-Nicalon Type-S, did not exhibit mechanical property degradation up to 10 dpa. Based on the materials data recently obtained, a very preliminary design window is provided and the future prospects of SiC/SiC technology integration is provided. (author)
Growth of CoSi2 on Si(001) by reactive deposition epitaxy

International Nuclear Information System (INIS)

Lim, C.W.; Shin, C.-S.; Gall, D.; Zuo, J.M.; Petrov, I.; Greene, J.E.

2005-01-01

CaF 2 -structure CoSi 2 layers were formed on Si(001) by reactive deposition epitaxy (RDE) and compared with CoSi 2 layers obtained by conventional solid phase growth (SPG). In both sets of experiments, Co was deposited by ultrahigh-vacuum magnetron sputtering and CoSi 2 formed at 600 deg. C. However, in the case of RDE, CoSi 2 formation occurred during Co deposition while for SPG, Co was deposited at 25 deg. C and silicidation took place during subsequent annealing. X-ray diffraction pole figures and transmission electron microscopy results demonstrate that RDE CoSi 2 layers are epitaxial with a cube-on-cube relationship (001) CoSi 2 parallel (001) Si and [100] CoSi 2 parallel[100] Si . In contrast, SPG films are polycrystalline with an average grain size of ≅1000 A and a mixed 111/002/022/112 orientation. We attribute the striking difference to rapid Co diffusion into the Si(001) substrate during RDE for which the high Co/Si reactivity gives rise to a flux-limited reaction resulting in the direct formation of the disilicide phase. In contrast, sequential nucleation and transformation among increasingly Si-rich phases--from orthorhombic Co 2 Si to cubic CoSi to CoSi 2 --during SPG results in polycrystalline layers with a complex texture
Microscopic and macroscopic characterization of the charging effects in SiC/Si nanocrystals/SiC sandwiched structures

International Nuclear Information System (INIS)

Xu, Jie; Xu, Jun; Wang, Yuefei; Cao, Yunqing; Li, Wei; Yu, Linwei; Chen, Kunji

2014-01-01

Microscopic charge injection into the SiC/Si nanocrystals/SiC sandwiched structures through a biased conductive AFM tip is subsequently characterized by both electrostatic force microscopy and Kelvin probe force microscopy (KPFM). The charge injection and retention characteristics are found to be affected by not only the band offset at the Si nanocrystals/SiC interface but also the doping type of the Si substrate. On the other hand, capacitance–voltage (C–V) measurements investigate the macroscopic charging effect of the sandwiched structures with a thicker SiC capping layer, where the charges are injected from the Si substrates. The calculated macroscopic charging density is 3–4 times that of the microscopic one, and the possible reason is the underestimation of the microscopic charging density caused by the averaging effect and detection delay in the KPFM measurements. (paper)
Comparative study of SiC- and Si-based photovoltaic inverters

Science.gov (United States)

Ando, Yuji; Oku, Takeo; Yasuda, Masashi; Shirahata, Yasuhiro; Ushijima, Kazufumi; Murozono, Mikio

2017-01-01

This article reports comparative study of 150-300 W class photovoltaic inverters (Si inverter, SiC inverter 1, and SiC inverter 2). In these sub-kW class inverters, the ON-resistance was considered to have little influence on the efficiency. The developed SiC inverters, however, have exhibited an approximately 3% higher direct current (DC)-alternating current (AC) conversion efficiency as compared to the Si inverter. Power loss analysis indicated a reduction in the switching and reverse recovery losses of SiC metal-oxide-semiconductor field-effect transistors used for the DC-AC converter is responsible for this improvement. In the SiC inverter 2, an increase of the switching frequency up to 100 kHz achieved a state-of-the-art combination of the weight (1.25 kg) and the volume (1260 cm3) as a 150-250 W class inverter. Even though the increased switching frequency should cause the increase of the switching losses, the SiC inverter 2 exhibited an efficiency comparable to the SiC inverter 1 with a switching frequency of 20 kHz. The power loss analysis also indicated a decreased loss of the DC-DC converter built with SiC Schottky barrier diodes led to the high efficiency for its increased switching frequency. These results clearly indicated feasibility of SiC devices even for sub-kW photovoltaic inverters, which will be available for the applications where compactness and efficiency are of tremendous importance.
[Efficacy of siRNA on feline leukemia virus replication in vitro].

Science.gov (United States)

Lehmann, Melanie; Weber, Karin; Rauch, Gisep; Hofmann-Lehmann, Regina; Hosie, Margaret J; Meli, Marina L; Hartmann, Katrin

2015-01-01

Feline leukemia virus (FeLV) can lead to severe clinical signs in cats. Until now, there is no effective therapy for FeLV-infected cats. RNA interference-based antiviral therapy is a new concept. Specific small interfering RNA (siRNA) are designed complementary to the mRNA of a target region, and thus inhibit replication. Several studies have proven efficacy of siRNAs in inhibiting virus replication. The aim of this study was to evaluate the inhibitory potential of siRNAs against FeLV replication in vitro. siRNAs against the FeLV env gene and the host cell surface receptor (feTHTR1) which is used by FeLV-A for entry as well as siRNA that were not complementary to the FeLV or cat genome, were tested. Crandell feline kidney cells (CrFK cells) were transfected with FeLV-A/Glasgow-1. On day 13, infected cells were transfected with siRNAs. As control, cells were mock-transfected or treated with azidothymidine (AZT) (5 μg/ml). Culture supernatants were analyzed for FeLV RNA using quantitative real-time RT-PCR and for FeLV p27 by ELISA every 24 hours for five days. All siRNAs significantly reduced viral RNA and p27 production, starting after 48 hours. The fact that non-complementary siRNAs also inhibited virus replication may lead to the conclusion that unspecific mechanisms rather than specific binding lead to inhibition.

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