WorldWideScience

Sample records for recombination layers formed

  1. Graded Recombination Layers for Multijunction Photovoltaics

    KAUST Repository

    Koleilat, Ghada I.; Wang, Xihua; Sargent, Edward H.

    2012-01-01

    it to achieve multicolor and spectrally tunable behavior. In series-connected current-matched multijunction devices, the recombination layers must allow the hole current from one cell to recombine, with high efficiency and low voltage loss, with the electron

  2. Graded Recombination Layers for Multijunction Photovoltaics

    KAUST Repository

    Koleilat, Ghada I.

    2012-06-13

    Multijunction devices consist of a stack of semiconductor junctions having bandgaps tuned across a broad spectrum. In solar cells this concept is used to increase the efficiency of photovoltaic harvesting, while light emitters and detectors use it to achieve multicolor and spectrally tunable behavior. In series-connected current-matched multijunction devices, the recombination layers must allow the hole current from one cell to recombine, with high efficiency and low voltage loss, with the electron current from the next cell. We recently reported a tandem solar cell in which the recombination layer was implemented using a progression of n-type oxides whose doping densities and work functions serve to connect, with negligible resistive loss at solar current densities, the constituent cells. Here we present the generalized conditions for design of efficient graded recombination layer solar devices. We report the number of interlayers and the requirements on work function and doping of each interlayer, to bridge an work function difference as high as 1.6 eV. We also find solutions that minimize the doping required of the interlayers in order to minimize optical absorption due to free carriers in the graded recombination layer (GRL). We demonstrate a family of new GRL designs experimentally and highlight the benefits of the progression of dopings and work functions in the interlayers. © 2012 American Chemical Society.

  3. Generation of truncated recombinant form of tumor necrosis factor ...

    African Journals Online (AJOL)

    7. Original Research Article. Generation of truncated recombinant form of tumor necrosis factor ... as 6×His tagged using E.coli BL21 (DE3) expression system. The protein was ... proapoptotic signaling cascade through TNFR1. [5] which is ...

  4. Recombiner

    International Nuclear Information System (INIS)

    Kikuchi, Nobuo.

    1983-01-01

    Purpose: To shorten the pre-heating time for a recombiner and obtain a uniform temperature distribution for the charged catalyst layer in a BWR type reactor. Constitution: A pre-heating heater is disposed to the outer periphery of a vessel for a recombiner packed with catalysts for recombining hydrogen and oxygen in gases flowing through a radioactive gaseous wastes processing system. Heat pipes for transmitting the heat applied to said container to the catalyst are disposed vertically and horizontally within the container. Different length of the heat pipes are combined. In this way, pre-heating time for the recombiner before the operation start and before the system switching can be shortened and the uniform pre-heating for the inside of the recombiner is also made possible. Further, heater control in the pre-heating can be carried out effectively and with ease. (Moriyama, K.)

  5. Generation of truncated recombinant form of tumor necrosis factor ...

    African Journals Online (AJOL)

    Purpose: To produce truncated recombinant form of tumor necrosis factor receptor 1 (TNFR1), cysteine-rich domain 2 (CRD2) and CRD3 regions of the receptor were generated using pET28a and E. coli/BL21. Methods: DNA coding sequence of CRD2 and CRD3 was cloned into pET28a vector and the corresponding ...

  6. Charge carriers bulk recombination instead of electroplex emission after their tunneling through hole-blocking layer in OLEDs

    Science.gov (United States)

    Yang, S. Y.; Liu, D.; Jiang, Y.; Teng, F.; Xu, Z.; Hou, Y.; Xu, X. R.

    2006-08-01

    Charge carriers bulk recombination instead of forming electroplex after their tunneling through a hole-blocking layer, i.e. 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), in organic electroluminescence (EL) device ITO/poly-(N-vinyl-carbazole)(PVK)/BCP/tris(8-hydroxyquinoline) aluminum (Alq3)/Al is reported. By changing the thickness of BCP layer, one can find that high electric fields enhance the tunneling process of holes accumulated at the PVK/BCP interface into BCP layer instead of forming “electroplex emission” as reported earlier in literatures. Our experimental data show that charge carriers bulk recombination takes place in both PVK layer and BCP layer, and even in Alq3 layer when BCP layer is thin enough. Further, it is suggested that PVK is the origin of the emission shoulder at 595 nm in the EL spectra of trilayer device ITO/PVK/BCP/Alq3/Al.

  7. Recombination pattern reanalysis of some HIV-1 circulating recombination forms suggest the necessity and difficulty of revision.

    Directory of Open Access Journals (Sweden)

    Lei Jia

    Full Text Available Recombination is one of the major mechanisms underlying the generation of HIV-1 variability. Currently 61 circulating recombinant forms of HIV-1 have been identified. With the development of recombination detection techniques and accumulation of HIV-1 reference stains, more accurate mosaic structures of circulating recombinant forms (CRFs, like CRF04 and CRF06, have undergone repeated analysis and upgrades. Such revisions may also be necessary for other CRFs. Unlike previous studies, whose results are based primarily on a single recombination detection program, the current study was based on multiple recombination analysis, which may have produced more impartial results.Representative references of 3 categories of intersubtype recombinants were selected, including BC recombinants (CRF07 and CRF08, BG recombinants (CRF23 and CRF24, and BF recombinants (CRF38 and CRF44. They were reanalyzed in detail using both the jumping profile hidden Markov model and RDP3.The results indicate that revisions and upgrades are very necessary and the entire re-analysis suggested 2 types of revision: (i length of inserted fragments; and (ii number of inserted fragments. The reanalysis also indicated that determination of small regions of about 200 bases or fewer should be performed with more caution.Results indicated that the involvement of multiple recombination detection programs is very necessary. Additionally, results suggested two major challenges, one involving the difficulty of accurately determining the locations of breakpoints and the second involving identification of small regions of about 200 bases or fewer with greater caution. Both indicate the complexity of HIV-1 recombination. The resolution would depend critically on development of a recombination analysis algorithm, accumulation of HIV-1 stains, and a higher sequencing quality. With the changes in recombination pattern, phylogenetic relationships of some CRFs may also change. All these results may

  8. Recombination barrier layers in solid-state quantum dot-sensitized solar cells

    KAUST Repository

    Roelofs, Katherine E.; Brennan, Thomas P.; Dominguez, Juan C.; Bent, Stacey F.

    2012-01-01

    in situ by successive ion layer adsorption and reaction (SILAR). Aluminum oxide recombination barrier layers were deposited by atomic layer deposition (ALD) at the TiO2/hole-conductor interface. For low numbers of ALD cycles, the Al2O3 barrier layer

  9. Nitrogen vacancies as a common element of the green luminescence and nonradiative recombination centers in Mg-implanted GaN layers formed on a GaN substrate

    Science.gov (United States)

    Kojima, Kazunobu; Takashima, Shinya; Edo, Masaharu; Ueno, Katsunori; Shimizu, Mitsuaki; Takahashi, Tokio; Ishibashi, Shoji; Uedono, Akira; Chichibu, Shigefusa F.

    2017-06-01

    The photoluminescences of ion-implanted (I/I) and epitaxial Mg-doped GaN (GaN:Mg) are compared. The intensities and lifetimes of the near-band-edge and ultraviolet luminescences associated with a MgGa acceptor of I/I GaN:Mg were significantly lower and shorter than those of the epilayers, respectively. Simultaneously, the green luminescence (GL) became dominant. These emissions were quenched far below room temperature. The results indicate the generation of point defects common to GL and nonradiative recombination centers (NRCs) by I/I. Taking the results of positron annihilation measurement into account, N vacancies are the prime candidate to emit GL and create NRCs with Ga vacancies, (VGa) m (VN) n , as well as to inhibit p-type conductivity.

  10. Method of forming buried oxide layers in silicon

    Science.gov (United States)

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2000-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  11. Intermolecular RNA Recombination Occurs at Different Frequencies in Alternate Forms of Brome Mosaic Virus RNA Replication Compartments

    Directory of Open Access Journals (Sweden)

    Hernan Garcia-Ruiz

    2018-03-01

    Full Text Available Positive-strand RNA viruses replicate their genomes in membrane-bound replication compartments. Brome mosaic virus (BMV replicates in vesicular invaginations of the endoplasmic reticulum membrane. BMV has served as a productive model system to study processes like virus-host interactions, RNA replication and recombination. Here we present multiple lines of evidence showing that the structure of the viral RNA replication compartments plays a fundamental role and that recruitment of parental RNAs to a common replication compartment is a limiting step in intermolecular RNA recombination. We show that a previously defined requirement for an RNA recruitment element on both parental RNAs is not to function as a preferred crossover site, but in order for individual RNAs to be recruited into the replication compartments. Moreover, modulating the form of the replication compartments from spherular vesicles (spherules to more expansive membrane layers increased intermolecular RNA recombination frequency by 200- to 1000-fold. We propose that intermolecular RNA recombination requires parental RNAs to be recruited into replication compartments as monomers, and that recruitment of multiple RNAs into a contiguous space is much more common for layers than for spherules. These results could explain differences in recombination frequencies between viruses that replicate in association with smaller spherules versus larger double-membrane vesicles and convoluted membranes.

  12. Reducing interface recombination for Cu(In,Ga)Se{sub 2} by atomic layer deposited buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Hultqvist, Adam; Bent, Stacey F. [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States); Li, Jian V.; Kuciauskas, Darius; Dippo, Patricia; Contreras, Miguel A.; Levi, Dean H. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    2015-07-20

    Partial CuInGaSe{sub 2} (CIGS) solar cell stacks with different atomic layer deposited buffer layers and pretreatments were analyzed by photoluminescence (PL) and capacitance voltage (CV) measurements to investigate the buffer layer/CIGS interface. Atomic layer deposited ZnS, ZnO, and SnO{sub x} buffer layers were compared with chemical bath deposited CdS buffer layers. Band bending, charge density, and interface state density were extracted from the CV measurement using an analysis technique new to CIGS. The surface recombination velocity calculated from the density of interface traps for a ZnS/CIGS stack shows a remarkably low value of 810 cm/s, approaching the range of single crystalline II–VI systems. Both the PL spectra and its lifetime depend on the buffer layer; thus, these measurements are not only sensitive to the absorber but also to the absorber/buffer layer system. Pretreatment of the CIGS prior to the buffer layer deposition plays a significant role on the electrical properties for the same buffer layer/CIGS stack, further illuminating the importance of good interface formation. Finally, ZnS is found to be the best performing buffer layer in this study, especially if the CIGS surface is pretreated with potassium cyanide.

  13. Double layers formed by beam driven ion-acoustic turbulence

    International Nuclear Information System (INIS)

    Ludwig, G.O.; Ferreira, J.L.; Montes, A.

    1987-01-01

    Small amplitude steady-state ion-acoustic layers are observed to form in a plasma traversed by a beam of cold electrons. The importance of turbulence in maintaining the double layer is demonstrated. The measured wave spectrum is in approximate agrreement with models derived from renormalized turbulence theory. The general features of the double layer are compared with results from particle simulation studies. (author) [pt

  14. Double layer formed by beam driven ion-acoustic turbulence

    International Nuclear Information System (INIS)

    Ludwig, G.O.; Ferreira, J.L.; Montes, A.

    1987-08-01

    Small amplitudes steady-state ion-acoustic double layers are observed to form in a plasma transversed by a beam of cold electrons. The importance of turbulence in maintaining the double layer is demonstrated. The measured wave spectrum is in approximate agreement with models deriveted from renornalized turbulence theory. The general features of the double layer are compared with results from particle simulation studies. (author) [pt

  15. Method of forming a nanocluster comprising dielectric layer and device comprising such a layer

    NARCIS (Netherlands)

    2009-01-01

    A method of forming a dielectric layer (330) on a further layer (114, 320) of a semiconductor device (300) is disclosed. The method comprises depositing a dielectric precursor compound and a further precursor compound over the further layer (114, 320), the dielectric precursor compound comprising a

  16. Recombiner

    International Nuclear Information System (INIS)

    Osumi, Morimichi.

    1979-01-01

    Purpose: To provide a recombiner which is capable of converting hydrogen gas into water by use of high-frequency heating at comparatively low temperatures and is safe and cheap in cost. Constitution: Hydrogen gas is introduced from an outer pipeline to the main structure of a recombiner, and when it passes through the vicinity of the central part of the recombiner, it is reacted with copper oxide (CuO 2 ) heated to a temperature more than 300 0 C by a high-frequency heater, and converted gently into water by reduction operation (2H 2 + CuO 2 → Cu + 2H 2 O). The thus prepared water is exhausted through the outer pipeline to a suppression pool. A part of hydrogen gas which has not been converted completely into water by the reaction and is remaining as hydrogen is recovered through exhaust nozzles and again introduced into the main structure of the recombiner. (Yoshino, Y.)

  17. Recombination barrier layers in solid-state quantum dot-sensitized solar cells

    KAUST Repository

    Roelofs, Katherine E.

    2012-06-01

    By replacing the dye in the dye-sensitized solar cell design with semiconductor quantum dots as the light-absorbing material, solid-state quantum dot-sensitized solar cells (ss-QDSSCs) were fabricated. Cadmium sulfide quantum dots (QDs) were grown in situ by successive ion layer adsorption and reaction (SILAR). Aluminum oxide recombination barrier layers were deposited by atomic layer deposition (ALD) at the TiO2/hole-conductor interface. For low numbers of ALD cycles, the Al2O3 barrier layer increased open circuit voltage, causing an increase in device efficiency. For thicker Al2O3 barrier layers, photocurrent decreased substantially, leading to a decrease in device efficiency. © 2012 IEEE.

  18. Specific features of waveguide recombination in laser structures with asymmetric barrier layers

    Energy Technology Data Exchange (ETDEWEB)

    Polubavkina, Yu. S., E-mail: polubavkina@mail.ru; Zubov, F. I.; Moiseev, E. I.; Kryzhanovskaya, N. V.; Maximov, M. V. [Russian Academy of Sciences, St. Petersburg National Research Academic University (Russian Federation); Semenova, E. S.; Yvind, K. [Technical University of Denmark, DTU Fotonik (Denmark); Asryan, L. V. [Virginia Polytechnic Institute and State University (United States); Zhukov, A. E. [Russian Academy of Sciences, St. Petersburg National Research Academic University (Russian Federation)

    2017-02-15

    The spatial distribution of the intensity of the emission caused by recombination appearing at a high injection level (up to 30 kA/cm{sup 2}) in the waveguide layer of a GaAs/AlGaAs laser structure with GaInP and AlGaInAs asymmetric barrier layers is studied by means of near-field scanning optical microscopy. It is found that the waveguide luminescence in such a laser, which is on the whole less intense as compared to that observed in a similar laser without asymmetric barriers, is non-uniformly distributed in the waveguide, so that the distribution maximum is shifted closer to the p-type cladding layer. This can be attributed to the ability of the GaInP barrier adjoining the quantum well on the side of the n-type cladding layer to suppress the hole transport.

  19. Specific features of waveguide recombination in laser structures with asymmetric barrier layers

    DEFF Research Database (Denmark)

    Polubavkina, Yu; Zubov, F. I.; Moiseev, E.

    2017-01-01

    microscopy. It is found that the waveguide luminescence in such a laser, which is on the whole less intense as compared to that observed in a similar laser without asymmetric barriers, is non-uniformly distributed in the waveguide, so that the distribution maximum is shifted closer to the p-type cladding......The spatial distribution of the intensity of the emission caused by recombination appearing at a high injection level (up to 30 kA/cm2) in the waveguide layer of a GaAs/AlGaAs laser structure with GaInP and AlGaInAs asymmetric barrier layers is studied by means of near-field scanning optical...... layer. This can be attributed to the ability of the GaInP barrier adjoining the quantum well on the side of the n-type cladding layer to suppress the hole transport....

  20. Rad52 forms DMA repair and recombination centers during S phase

    DEFF Research Database (Denmark)

    Lisby, M.; Rothstein, R.; Mortensen, Uffe Hasbro

    2001-01-01

    fluorescent protein (GFP) is fully functional in DNA repair and recombination. After induction of DNA double-strand breaks by gamma -irradiation, meiosis, or the HO endonuclease, Rad52-GFP relocalizes from a diffuse nuclear distribution to distinct foci. Interestingly, Rad52 foci are formed almost exclusively...

  1. Four Closely Related HIV-1 CRF01_AE/CRF07_BC Recombinant Forms Identified in East China.

    Science.gov (United States)

    Li, Fan; Li, Yuxueyun; Feng, Yi; Hu, Jing; Ruan, Yuhua; Xing, Hui; Shao, Yiming

    2017-07-01

    Five near full-length genomes of novel second-generation HIV-1 recombinant virus (JS150021, JS150029, JS150129, JS150132, and AH150183) were identified from five HIV-positive people in Jiangsu and Anhui province, east China. Phylogenic analyses showed that these five sequences are all composed of two well-established circulating recombinant forms (CRFs) CRF07_BC and CRF01_AE, grouped into four new discovered recombinant forms, which show several very similar but not identical recombinant breakpoints. The four recombinant forms are also identified to be a sort of family or related viruses, seems to be the results of different recombination events. The emergence of a serious new closely related CRF07_BC/CRF01_AE recombinant strain indicates the increasing complexity of sexual transmission of the HIV-1 epidemic in China.

  2. Nature of radiative recombination processes in layered semiconductor PbCdI{sub 2} nanostructural scintillation material

    Energy Technology Data Exchange (ETDEWEB)

    Bukivskii, A.P. [Institute of Physics of the National Academy of Sciences of Ukraine, 03028 Kyiv (Ukraine); Gnatenko, Yu.P., E-mail: yuriygnatenko@ukr.net [Institute of Physics of the National Academy of Sciences of Ukraine, 03028 Kyiv (Ukraine); Piryatinskii, Yu.P. [Institute of Physics of the National Academy of Sciences of Ukraine, 03028 Kyiv (Ukraine); Gamernyk, R.V. [Lviv National University, 8 Kyryl o and Mefodiy Str., 29005 Lviv (Ukraine)

    2017-05-15

    We report on the efficient photoluminescence (PL) and radioluminescence (RL) of the PbI{sub 2} nanoclusters (NCLs), which are naturally formed in the nanostructured Pb{sub 1-X}Cd{sub x}I{sub 2} alloys (X=0.70). Here, we carried out the studies of the nature of radiative recombination processes in the NCLs of various sizes by measuring PL temperature evolution. Our results indicate that at low temperatures the PL is mainly caused by exciton emission and recombination of donor-acceptor pairs, generated in volume of large NCLs. The broad bands, which are associated with the deep intrinsic surface states, including self-trapped excitons (STEs), are dominant in the PL spectra at higher temperature (>100 K). Our work shows that the nature of emission, associated with RL bands is analogous to that for PL bands. It was shown that the investigated nanostructured material is strongly radiation-resistant. Thus, the Pb{sub 1-X}Cd{sub X}I{sub 2} alloys can be considered as new effective layered semiconductor nanostructured materials which can be suitable for the elaboration of perspective semiconductor scintillators. These nanomaterials have promising prospects for applications in new generations of devices for biomedical diagnostics and industrial imaging applications. - Highlights: •The intense PL and RL of nanostructural PbCdI{sub 2} alloys were observed. •The nature of recombination processes of the nanoscintillators was established. •The low temperature PL is caused by exciton and donor-acceptor pairs recombination. •The broad PL bands are due to the deep intrinsic states formed on the NCLs surface. •The PL associated with STEs for NCLs of different sizes was analyzed in detail. •It was shown that the nature of PL and RL spectra is same.

  3. Recombinant Programming

    OpenAIRE

    Pawlak , Renaud; Cuesta , Carlos; Younessi , Houman

    2004-01-01

    This research report presents a promising new approach to computation called Recombinant Programming. The novelty of our approach is that it separates the program into two layers of computation: the recombination and the interpretation layer. The recombination layer takes sequences as inputs and allows the programmer to recombine these sequences through the definition of cohesive code units called extensions. The output of such recombination is a mesh that can be used by the interpretation la...

  4. Conserved S-Layer-Associated Proteins Revealed by Exoproteomic Survey of S-Layer-Forming Lactobacilli

    Science.gov (United States)

    Johnson, Brant R.; Hymes, Jeffrey; Sanozky-Dawes, Rosemary; Henriksen, Emily DeCrescenzo

    2015-01-01

    The Lactobacillus acidophilus homology group comprises Gram-positive species that include L. acidophilus, L. helveticus, L. crispatus, L. amylovorus, L. gallinarum, L. delbrueckii subsp. bulgaricus, L. gasseri, and L. johnsonii. While these bacteria are closely related, they have varied ecological lifestyles as dairy and food fermenters, allochthonous probiotics, or autochthonous commensals of the host gastrointestinal tract. Bacterial cell surface components play a critical role in the molecular dialogue between bacteria and interaction signaling with the intestinal mucosa. Notably, the L. acidophilus complex is distinguished in two clades by the presence or absence of S-layers, which are semiporous crystalline arrays of self-assembling proteinaceous subunits found as the outermost layer of the bacterial cell wall. In this study, S-layer-associated proteins (SLAPs) in the exoproteomes of various S-layer-forming Lactobacillus species were proteomically identified, genomically compared, and transcriptionally analyzed. Four gene regions encoding six putative SLAPs were conserved in the S-layer-forming Lactobacillus species but not identified in the extracts of the closely related progenitor, L. delbrueckii subsp. bulgaricus, which does not produce an S-layer. Therefore, the presence or absence of an S-layer has a clear impact on the exoproteomic composition of Lactobacillus species. This proteomic complexity and differences in the cell surface properties between S-layer- and non-S-layer-forming lactobacilli reveal the potential for SLAPs to mediate intimate probiotic interactions and signaling with the host intestinal mucosa. PMID:26475115

  5. Recombiner

    International Nuclear Information System (INIS)

    Saalfrank, H.

    1985-01-01

    Air containing hydrogen can be oxidized by heating in a container called a recombiner, in order to avoid the collection of hydrogen. The container is long and a large number of straight heating bars are arranged in parallel in it and they are flanged to a lid. The heating bars are surrounded by tubes, in order to obtain good heat transfer by a narrow annular gap. (orig.) [de

  6. Recombination zone in white organic light emitting diodes with blue and orange emitting layers

    Science.gov (United States)

    Tsuboi, Taiju; Kishimoto, Tadashi; Wako, Kazuhiro; Matsuda, Kuniharu; Iguchi, Hirofumi

    2012-10-01

    White fluorescent OLED devices with a 10 nm thick blue-emitting layer and a 31 nm thick orange-emitting layer have been fabricated, where the blue-emitting layer is stacked on a hole transport layer. An interlayer was inserted between the two emitting layers. The thickness of the interlayer was changed among 0.3, 0.4, and 1.0 nm. White emission with CIE coordinates close to (0.33, 0.33) was observed from all the OLEDs. OLED with 0.3 nm thick interlayer gives the highest maximum luminous efficiency (11 cd/A), power efficiency (9 lm/W), and external quantum efficiency (5.02%). The external quantum efficiency becomes low with increasing the interlayer thickness from 0 nm to 1.0 nm. When the location of the blue- and orange-emitting layers is reversed, white emission was not obtained because of too weak blue emission. It is suggested that the electron-hole recombination zone decreases nearly exponentially with a distance from the hole transport layer.

  7. Fast and easy protocol for the purification of recombinant S-layer protein for synthetic biology applications

    KAUST Repository

    Norville, Julie E.

    2011-06-17

    A goal of synthetic biology is to make biological systems easier to engineer. One of the aims is to design, with nanometer-scale precision, biomaterials with well-defined properties. The surface-layer protein SbpA forms 2D arrays naturally on the cell surface of Lysinibacillus sphaericus, but also as the purified protein in solution upon the addition of divalent cations. The high propensity of SbpA to form crystalline arrays, which can be simply controlled by divalent cations, and the possibility to genetically alter the protein, make SbpA an attractive molecule for synthetic biology. To be a useful tool, however, it is important that a simple protocol can be used to produce recombinant wild-type and modified SbpA in large quantities and in a biologically active form. The present study addresses this requirement by introducing a mild and non-denaturing purification protocol to produce milligram quantities of recombinant, active SbpA.

  8. Neutron activation analysis of baths forming conversion layer on aluminium

    International Nuclear Information System (INIS)

    Szilagyi, Istvan; Maleczki, Emil; Bodizs, Denes

    1988-01-01

    Chromate layers were formed on the surface of aluminium using yellow and green chromating solutions. For the determination of the aluminium content neutron activation method was used. Nuclear effects disturbing the determination were eliminated by double irradiation technique. (author) 8 refs.; 4 figs

  9. Emergence of new forms of human immunodeficiency virus type 1 intersubtype recombinants in central Myanmar.

    Science.gov (United States)

    Motomura, K; Kusagawa, S; Kato, K; Nohtomi, K; Lwin, H H; Tun, K M; Thwe, M; Oo, K Y; Lwin, S; Kyaw, O; Zaw, M; Nagai, Y; Takebe, Y

    2000-11-20

    We have previously shown that HIV-1 env subtypes B' (a Thai-B cluster within subtype B) and E (CRF01_AE) are distributed in Yangon, the capital city of Myanmar. However, HIV strains from the rest of country have not yet been genetically characterized. In the present study, we determined env (C2/V3) and gag (p17) subtypes of 25 specimens from central Myanmar (Mandalay). Phylogenetic analyses identified 5 subtype C (20%), in addition to 10 CRF01_AE (40%) and 4 subtype B' (16%). Interestingly, the remaining six specimens (24%) showed discordance between gag and env subtypes; three gag subtype B'/env subtype C, one gag subtype B'/env subtype E, one gag subtype C/env subtype B', and one gag subtype C/env subtype E. These discordant specimens were found frequently among injecting drug users (4 of 12, 33%) and female commercial sex workers (2 of 8, 25%) engaging in high-risk behaviors. The recombinant nature of these HIV-1 strains was verified in three specimens, indicating the presence of new forms of HIV-1 intersubtype C/B' and C/B'/E recombinants with different recombination breakpoints. The data suggest that multiple subtypes of B', C, and CRF01_AE are cocirculating in central Myanmar, leading to the evolution of new forms of intersubtype recombinants among the risk populations exhibiting one of the highest HIV infection rates in the region.

  10. Spin-dependent tunneling recombination in heterostructures with a magnetic layer

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, K. S., E-mail: denisokonstantin@gmail.com; Rozhansky, I. V.; Averkiev, N. S. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Lähderanta, E. [Lappeenranta University of Technology (Finland)

    2017-01-15

    We propose a mechanism for the generation of spin polarization in semiconductor heterostructures with a quantum well and a magnetic impurity layer spatially separated from it. The spin polarization of carriers in a quantum well originates from spin-dependent tunneling recombination at impurity states in the magnetic layer, which is accompanied by a fast linear increase in the degree of circular polarization of photoluminescence from the quantum well. Two situations are theoretically considered. In the first case, resonant tunneling to the spin-split sublevels of the impurity center occurs and spin polarization is caused by different populations of resonance levels in the quantum well for opposite spin projections. In the second, nonresonant case, the spin-split impurity level lies above the occupied states of electrons in the quantum well and plays the role of an intermediate state in the two-stage coherent spin-dependent recombination of an electron from the quantum well and a hole in the impurity layer. The developed theory allows us to explain both qualitatively and quantitatively the kinetics of photoexcited electrons in experiments with photoluminescence with time resolution in Mn-doped InGaAs heterostructures.

  11. Calcium dependent formation of tubular assemblies by recombinant S-layer proteins in vivo and in vitro

    Science.gov (United States)

    Korkmaz, Nuriye; Ostermann, Kai; Rödel, Gerhard

    2011-03-01

    Surface layer proteins have the appealing property to self-assemble in nanosized arrays in solution and on solid substrates. In this work, we characterize the formation of assembly structures of the recombinant surface layer protein SbsC of Geobacillus stearothermophilus ATTC 12980, which was tagged with enhanced green fluorescent protein and expressed in the yeast Saccharomyces cerevisiae. The tubular structures formed by the protein in vivo are retained upon bursting the cells by osmotic shock; however, their average length is decreased. During dialysis, monomers obtained by treatment with chaotropic chemicals recrystallize again to form tube-like structures. This process is strictly dependent on calcium (Ca2 + ) ions, with an optimal concentration of 10 mM. Further increase of the Ca2 + concentration results in multiple non-productive nucleation points. We further show that the lengths of the S-layer assemblies increase with time and can be controlled by pH. After 48 h, the average length at pH 9.0 is 4.13 µm compared to 2.69 µm at pH 5.5. Successful chemical deposition of platinum indicates the potential of recrystallized mSbsC-eGFP structures for nanobiotechnological applications.

  12. Resolving the Gordian Knot: Srs2 Strips Intermediates Formed during Homologous Recombination.

    Science.gov (United States)

    Ghodke, Harshad; Lewis, Jacob S; van Oijen, Antoine M

    2018-03-01

    Cells use a suite of specialized enzymes to repair chromosomal double-strand breaks (DSBs). Two recent studies describe how single-molecule fluorescence imaging techniques are used in the direct visualization of some of the key molecular steps involved. De Tullio et al. and Kaniecki et al. watch individual Srs2 helicase molecules disrupt repair intermediates formed by RPA, Rad51, and Rad52 on DNA during homologous recombination. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Dissociation–recombination models in hypersonic boundary layer O2/O flows

    International Nuclear Information System (INIS)

    Armenise, I.; Esposito, F.

    2012-01-01

    Graphical abstract: In hypersonic boundary layers, in which the temperature strongly decreases from the edge to the body surface, the coupling of transport phenomena and chemical kinetics causes a strong vibrational non-equilibrium, as demonstrated by the vibrational distributions and the pseudo-first-order dissociation constants. In this work a pure O2/O mixture has been investigated to evaluate the role of new multiquanta atom-molecule collision rate coefficients, calculated by means of a quasiclassical trajectory (QCT) method. Highlights: ► We evaluate the vibrational non-equilibrium in oxygen hypersonic boundary layer flows. ► We adopt a state-to-state vibrational kinetics model. ► We use updated quasicassical trajectory atom–molecule collision rate coefficients. ► Multiquanta transitions and direct dissociation–recombination are important. ► We calculate the heat flux through the boundary layer. - Abstract: A recent complete set of oxygen atom–molecule collision rate coefficients, calculated by means of a quasiclassical trajectory (QCT) method, has been used to evaluate the vibrational non-equilibrium in hypersonic boundary layer flows. The importance of multiquanta transitions has been demonstrated. Moreover a new ‘direct dissociation–recombination’ (DDR) model has been adopted and the corresponding results differ from the ones obtained with the ladder-climbing (LC) model, characterized by the extrapolation of bound-to-bound transitions to the continuum. The heat flux through the boundary layer and at the surface has been calculated too.

  14. Emergence of recombinant forms in geographic regions with co-circulating HIV subtypes in the dynamic HIV-1 epidemic

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ming [Los Alamos National Laboratory; Letiner, Thomas K [Los Alamos National Laboratory; Korber, Bette T [Los Alamos National Laboratory; Foley, Brian [Los Alamos National Laboratory

    2009-01-01

    We have reexamined the subtype designations of {approx}10,000 subtype A, B, C, G, and AG, BC, BF recombinant sequences, and compared the results of the new analysis with their published designations. Intersubtype recombinants dominate HIV epidemics in three different geographical regions. The circulating recombinant from (CRF) CRF02-AG, common in West Central Africa, appears to result from a recombination event that occurred early in the divergence between subtypes A and G, although additional more recent recombination events may have contributed to the breakpoint pattern in this recombinant lineage as well. The Chinese recombinant epidemic strains CRF07 and CRF08, in contrast, result from recent recombinations between more contemporary strains. Nevertheless, CRF07 and CRF08 contributed to many subsequent recombination events. The BF recombinant epidemics in two HIV-1 epicenters in South America are not independent and BF epidemics in South America have an unusually high fraction of unique recombinant forms (URFs) that have each been found only once and carry distinctive breakpoints. Taken together, these analyses reveal a complex and dynamic picture of the current HIV-1 epidemic, and suggest a means of grouping and tracking relationships between viruses through preservation of shared breakpints.

  15. Spontaneous layering of porous silicon layers formed at high current densities

    Energy Technology Data Exchange (ETDEWEB)

    Parkhutik, Vitali; Curiel-Esparza, Jorge; Millan, Mari-Carmen [R and D Center MTM, Technical University of Valencia, Valencia (Spain); Albella, Jose [Institute of Materials Science (ICMM CSIC) Madrid (Spain)

    2005-06-01

    We report here a curious effect of spontaneous fracturing of the silicon layers formed in galvanostatic conditions at medium and high current densities. Instead of formation of homogeneous p-Si layer as at low currents, a stack of thin layers is formed. Each layer is nearly separated from others and possesses rather flat interfaces. The effects is observed using p{sup +}-Si wafers for the p-Si formation and starts being noticeable at above 100 mA/cm{sup 2}. We interpret these results in terms of the porous silicon growth model where generation of dynamic mechanical stress during the p-Si growth causes sharp changes in Si dissolution mechanism from anisotropic etching of individual needle-like pores in silicon to their branching and isotropic etching. At this moment p-Si layer loses its adhesion to the surface of Si wafer and another p-Si layer starts growing. One of the mechanisms triggering on the separation of p-Si layers from one another is a fluctuation of local anodic current in the pore bottoms associated with gas bubble evolution during the p-Si formation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Hybrid tandem photovoltaic devices with a transparent conductive interconnecting recombination layer

    International Nuclear Information System (INIS)

    Kim, Taehee; Choi, Jin Young; Jeon, Jun Hong; Kim, Youn-Su; Kim, Bong-Soo; Lee, Doh-Kwon; Kim, Honggon; Han, Seunghee; Kim, Kyungkon

    2012-01-01

    Highlights: ► This work enhanced power conversion efficiency of the hybrid tandem solar cell from 1.0% to 2.6%. ► The interfacial series resistance of the tandem solar cell was eliminated by inserting ITO layer. ► This work shows the feasibility of the highly efficient hybrid tandem solar cells. -- Abstract: We demonstrate hybrid tandem photovoltaic devices with a transparent conductive interconnecting recombination layer. The series-connected hybrid tandem photovoltaic devices were developed by combining hydrogenated amorphous silicon (a-Si:H) and polymer-based organic photovoltaics (OPVs). In order to enhance the interfacial connection between the subcells, we employed highly transparent and conductive indium tin oxide (ITO) thin layer. By using the ITO interconnecting layer, the power conversion efficiency of the hybrid tandem solar cell was enhanced from 1.0% (V OC = 1.041 V, J SC = 2.97 mA/cm 2 , FF = 32.3%) to 2.6% (V OC = 1.336 V, J SC = 4.65 mA/cm 2 , FF = 41.98%) due to the eliminated interfacial series resistance.

  17. Tandem colloidal quantum dot solar cells employing a graded recombination layer

    KAUST Repository

    Wang, Xihua; Koleilat, Ghada I.; Tang, Jiang; Liu, Huan; Kramer, Illan J.; Debnath, Ratan; Brzozowski, Lukasz; Barkhouse, D. Aaron R.; Levina, Larissa; Hoogland, Sjoerd; Sargent, Edward H.

    2011-01-01

    Tuning of the electronic bandgap in colloidal quantum dots (CQDs) by changing their size enables the spectral response of CQD-based photodetectors and photovoltaic devices to be tailored. Multi-junction solar cells made from a combination of CQDs of differing sizes and thus bandgaps are a promising means by which to increase the energy harvested from the Sun's broad spectrum. Here, we report the first CQD tandem solar cells using the size-effect tuning of a single CQD material, PbS. We use a graded recombination layer to provide a progression of work functions from the hole-accepting electrode in the bottom cell to the electron-accepting electrode in the top cell, allowing matched electron and hole currents to meet and recombine. Our tandem solar cell has an open-circuit voltage of 1.06Â V, equal to the sum of the two constituent single-junction devices, and a solar power conversion efficiency of up to 4.2%. © 2011 Macmillan Publishers Limited. All rights reserved.

  18. Tandem colloidal quantum dot solar cells employing a graded recombination layer

    KAUST Repository

    Wang, Xihua

    2011-06-26

    Tuning of the electronic bandgap in colloidal quantum dots (CQDs) by changing their size enables the spectral response of CQD-based photodetectors and photovoltaic devices to be tailored. Multi-junction solar cells made from a combination of CQDs of differing sizes and thus bandgaps are a promising means by which to increase the energy harvested from the Sun\\'s broad spectrum. Here, we report the first CQD tandem solar cells using the size-effect tuning of a single CQD material, PbS. We use a graded recombination layer to provide a progression of work functions from the hole-accepting electrode in the bottom cell to the electron-accepting electrode in the top cell, allowing matched electron and hole currents to meet and recombine. Our tandem solar cell has an open-circuit voltage of 1.06Â V, equal to the sum of the two constituent single-junction devices, and a solar power conversion efficiency of up to 4.2%. © 2011 Macmillan Publishers Limited. All rights reserved.

  19. Che a 1: recombinant expression, purification and correspondence to the natural form.

    Science.gov (United States)

    Barderas, Rodrigo; Villalba, Mayte; Rodríguez, Rosalía

    2004-12-01

    Pollinosis to chenopods is one of the main causes of allergy in desertic regions and it is increasing in the South of Europe and Western USA. Che a 1 is a major allergen for chenopod-allergic subjects and belongs to the Ole-e-1-like family of proteins. Pichia pastoris yeast has been used as expression system to produce the recombinant form of Che a 1 (rChe a 1). The allergen was isolated using a gel permeation column and reverse-phase/high-performance liquid chromatography. Molecular characterization was performed using Edman degradation, mass spectrometry and concanavalin A staining. Sera from patients allergic to chenopod pollen, as well as polyclonal and monoclonal antibodies raised against Ole e 1, were used in immunoblotting, ELISA and inhibition assays for immunological characterization of rChe a 1. The allergen was purified to homogeneity with a final yield of 15 mg/l of cell culture and showed a glycosylated character. N-terminal amino acid sequence of rChe a 1 and molecular mass were according to those of the protein isolated from chenopod pollen. The recombinant allergen maintained the IgG and IgE epitopes of the natural allergen deduced from the immunological assays. Structural and in vitro immunological properties of rChe a 1 produced in P. pastoris were equivalent to those of the natural form of the allergen and, thus, it could be used in testing patients allergic to chenopods. 2004 S. Karger AG, Basel.

  20. Topotactic condensation of layer silicates with ferrierite-type layers forming porous tectosilicates.

    Science.gov (United States)

    Marler, B; Wang, Y; Song, J; Gies, H

    2014-07-21

    Five different hydrous layer silicates (HLSs) containing fer layers (ferrierite-type layers) were obtained by hydrothermal syntheses from mixtures of silicic acid, water and tetraalkylammonium/tetraalkylphosphonium hydroxides. The organic cations had been added as structure directing agents (SDA). A characteristic feature of the structures is the presence of strong to medium strong hydrogen bonds between the terminal silanol/siloxy groups of neighbouring layers. The five-layered silicates differ chemically only with respect to the organic cations. Structurally, they differ with respect to the arrangement of the fer layers relative to each other, which is distinct for every SDA-fer-layer system. RUB-20 (containing tetramethylammonium) and RUB-40 (tetramethylphosphonium) are monoclinic with stacking sequence AAA and shift vectors between successive layers 1a0 + 0b0 + 0.19c0 and 1a0 + 0b0 + 0.24c0, respectively. RUB-36 (diethyldimethylammonium), RUB-38 (methyltriethylammonium) and RUB-48 (trimethylisopropylammonium) are orthorhombic with stacking sequence ABAB and shift vectors 0.5a0 + 0b0± 0.36c0, 0.5a0 + 0b0 + 0.5c0 and 0.5a0 + 0b0± 0.39c0, respectively. Unprecedented among the HLSs, two monoclinic materials are made up of fer layers which possess a significant amount of ordered defects within the layer. The ordered defects involve one particular Si-O-Si bridge which is, to a fraction of ca. 50%, hydrolyzed to form nests of two ≡Si-OH groups. When heated to 500-600 °C in air, the HLSs condense to form framework silicates. Although all layered precursors were moderately to well ordered, the resulting framework structures were of quite different crystallinity. The orthorhombic materials RUB-36, -38 and -48, general formula SDA4Si36O72(OH)4, which possess very strong hydrogen bonds (d[O···O] ≈ 2.4 Å), transform into a fairly or well ordered CDO-type silica zeolite RUB-37. The monoclinic materials RUB-20 and -40, general formula SDA2Si18O36(OH)2OH, possessing

  1. Recombination region improvement for reduced efficiency roll-off in phosphorescent OLEDs with dual emissive layers

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhu; Zhou, Shunliang [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Hu, Song [Chengdu Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China); Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2014-10-15

    High-performance phosphorescent organic light-emitting diodes (PhOLEDs) by using dual-emissive-layer (DEL) structure to reduce efficiency roll-off were fabricated. The DEL was comprised of a hole-transport-type host of N, N′-bis(naphthalen-1-yl)-N, N′-bis(phenyl)-benzidine (NPB) and a bipolar host of 4,4′-bis(carbazol-9-yl)biphenyl (CBP), which were both doped with an orange phosphorescent dopant of bis[2-(4-tert-butylphenyl)-benzothiazolato-N,C2′]iridium (acetylacetonate) [(t-bt){sub 2}Ir(acac)]. After the optimization of doping concentration of the first emissive layer (FEL), the device with DEL exhibited 11% lower roll-off power efficiency than single emissive layer devices (SED) when the luminance increased from 1000 cd/m{sup 2} to 10,000 cd/m{sup 2}. The hole–electron recombination zone in DEL was illuminated by inserting an ultrathin fluorescent probe of 4-(dicyanomethylene)-2-tert-butyl-6 (1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) in different emissive regions. The performance improvement was attributed to the optimization of energy barrier and the expansion of exciton formation zone within the DEL. - Highlights: • PhOLEDs by using a dual-emissive-layer structure to reduce efficiency roll-off were fabricated. • The DED exhibited 11% lower efficiency roll-off, 57% lower turn-on voltage, and 174% higher brightness than SED. • A DCJTB fluorescent probe was inserted at different positions of DED to investigate the expansion of exciton formation zone.

  2. Effect of Al 2 O 3 Recombination Barrier Layers Deposited by Atomic Layer Deposition in Solid-State CdS Quantum Dot-Sensitized Solar Cells

    KAUST Repository

    Roelofs, Katherine E.

    2013-03-21

    Despite the promise of quantum dots (QDs) as a light-absorbing material to replace the dye in dye-sensitized solar cells, quantum dot-sensitized solar cell (QDSSC) efficiencies remain low, due in part to high rates of recombination. In this article, we demonstrate that ultrathin recombination barrier layers of Al2O3 deposited by atomic layer deposition can improve the performance of cadmium sulfide (CdS) quantum dot-sensitized solar cells with spiro-OMeTAD as the solid-state hole transport material. We explored depositing the Al2O3 barrier layers either before or after the QDs, resulting in TiO2/Al2O3/QD and TiO 2/QD/Al2O3 configurations. The effects of barrier layer configuration and thickness were tracked through current-voltage measurements of device performance and transient photovoltage measurements of electron lifetimes. The Al2O3 layers were found to suppress dark current and increase electron lifetimes with increasing Al 2O3 thickness in both configurations. For thin barrier layers, gains in open-circuit voltage and concomitant increases in efficiency were observed, although at greater thicknesses, losses in photocurrent caused net decreases in efficiency. A close comparison of the electron lifetimes in TiO2 in the TiO2/Al2O3/QD and TiO2/QD/Al2O3 configurations suggests that electron transfer from TiO2 to spiro-OMeTAD is a major source of recombination in ss-QDSSCs, though recombination of TiO2 electrons with oxidized QDs can also limit electron lifetimes, particularly if the regeneration of oxidized QDs is hindered by a too-thick coating of the barrier layer. © 2013 American Chemical Society.

  3. Effects of Organic Cation Length on Exciton Recombination in Two-Dimensional Layered Lead Iodide Hybrid Perovskite Crystals.

    Science.gov (United States)

    Gan, Lu; Li, Jing; Fang, Zhishan; He, Haiping; Ye, Zhizhen

    2017-10-19

    In recent years, 2D layered organic-inorganic lead halide perovskites have attracted considerable attention due to the distinctive quantum confinement effects as well as prominent excitonic luminescence. Herein, we show that the recombination dynamics and photoluminescence (PL) of the 2D layered perovskites can be tuned by the organic cation length. 2D lead iodide perovskite crystals with increased length of the organic chains reveal blue-shifted PL as well as enhanced relative internal quantum efficiency. Furthermore, we provide experimental evidence that the formation of face-sharing [PbI 6 ] 4- octahedron in perovskites with long alkyls induces additional confinement for the excitons, leading to 1D-like recombination. As a result, the PL spectra show enhanced inhomogeneous broadening at low temperature. Our work provides physical understanding of the role of organic cation in the optical properties of 2D layered perovskites, and would benefit the improvement of luminescence efficiency of such materials.

  4. First identification of a recombinant form of hepatitis C virus in Austrian patients by full-genome next generation sequencing.

    Science.gov (United States)

    Stelzl, Evelyn; Haas, Bernhard; Bauer, Bernd; Zhang, Sherry; Fiss, Ellen H; Hillman, Grantland; Hamilton, Aaron T; Mehta, Rochak; Heil, Marintha L; Marins, Ed G; Santner, Brigitte I; Kessler, Harald H

    2017-01-01

    Hepatitis C virus (HCV) intergenotypic recombinant forms have been reported for various HCV genotypes/subtypes in several countries worldwide. In a recent study, four patients living in Austria had been identified to be possibly infected with a recombinant HCV strain. To clarify results and determine the point of recombination, full-genome next-generation sequencing using the Illumina MiSeq v2 300 cycle kit (Illumina, San Diego, CA, USA) was performed in the present study. Samples of all of the patients contained the recombinant HCV strain 2k/1b. The point of recombination was found to be within the HCV NS2 gene between nucleotide positions 3189-3200 based on H77 numbering. While three of four patients were male and had migration background from Chechnya (n = 2) and Azerbaijan (n = 1), the forth patient was a female born in Austria. Three of the four patients including the female had intravenous drug abuse as a risk factor for HCV transmission. While sequencing techniques are limited to a few specialized laboratories, a genotyping assay that uses both ends of the HCV genome should be employed to identify patients infected with a recombinant HCV strain. The correct identification of recombinant strains also has an impact considering the tailored choice of anti-HCV treatment.

  5. First identification of a recombinant form of hepatitis C virus in Austrian patients by full-genome next generation sequencing.

    Directory of Open Access Journals (Sweden)

    Evelyn Stelzl

    Full Text Available Hepatitis C virus (HCV intergenotypic recombinant forms have been reported for various HCV genotypes/subtypes in several countries worldwide. In a recent study, four patients living in Austria had been identified to be possibly infected with a recombinant HCV strain. To clarify results and determine the point of recombination, full-genome next-generation sequencing using the Illumina MiSeq v2 300 cycle kit (Illumina, San Diego, CA, USA was performed in the present study. Samples of all of the patients contained the recombinant HCV strain 2k/1b. The point of recombination was found to be within the HCV NS2 gene between nucleotide positions 3189-3200 based on H77 numbering. While three of four patients were male and had migration background from Chechnya (n = 2 and Azerbaijan (n = 1, the forth patient was a female born in Austria. Three of the four patients including the female had intravenous drug abuse as a risk factor for HCV transmission. While sequencing techniques are limited to a few specialized laboratories, a genotyping assay that uses both ends of the HCV genome should be employed to identify patients infected with a recombinant HCV strain. The correct identification of recombinant strains also has an impact considering the tailored choice of anti-HCV treatment.

  6. The multilayer nanoparticles formed by layer by layer approach for cancer-targeting therapy.

    Science.gov (United States)

    Oh, Keun Sang; Lee, Hwanbum; Kim, Jae Yeon; Koo, Eun Jin; Lee, Eun Hee; Park, Jae Hyung; Kim, Sang Yoon; Kim, Kwangmeyung; Kwon, Ick Chan; Yuk, Soon Hong

    2013-01-10

    The multilayer nanoparticles (NPs) were prepared for cancer-targeting therapy using the layer by layer approach. When drug-loaded Pluronic NPs were mixed with vesicles (liposomes) in the aqueous medium, Pluronic NPs were incorporated into the vesicles to form the vesicle NPs. Then, the multilayer NPs were formed by freeze-drying the vesicle NPs in a Pluronic aqueous solution. The morphology and size distribution of the multilayer NPs were observed using a TEM and a particle size analyzer. In order to apply the multilayer NPs as a delivery system for docetaxel (DTX), which is a model anticancer drug, the release pattern of the DTX was observed and the tumor growth was monitored by injecting the multilayer NPs into the tail veins of tumor (squamous cell carcinoma)-bearing mice. The cytotoxicity of free DTX (commercial DTX formulation (Taxotere®)) and the multilayer NPs was evaluated using MTT assay. We also evaluated the tumor targeting ability of the multilayer NPs using magnetic resonance imaging. The multilayer NPs showed excellent tumor targetability and antitumor efficacy in tumor-bearing mice, caused by the enhanced permeation and retention (EPR) effect. These results suggest that the multilayer NPs could be a potential drug delivery system for cancer-targeting therapy. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Optimization of Recombination Layer in the Tunnel Junction of Amorphous Silicon Thin-Film Tandem Solar Cells

    Directory of Open Access Journals (Sweden)

    Yang-Shin Lin

    2011-01-01

    Full Text Available The amorphous silicon/amorphous silicon (a-Si/a-Si tandem solar cells have attracted much attention in recent years, due to the high efficiency and low manufacturing cost compared to the single-junction a-Si solar cells. In this paper, the tandem cells are fabricated by high-frequency plasma-enhanced chemical vapor deposition (HF-PECVD at 27.1 MHz. The effects of the recombination layer and the i-layer thickness matching on the cell performance have been investigated. The results show that the tandem cell with a p+ recombination layer and i2/i1 thickness ratio of 6 exhibits a maximum efficiency of 9.0% with the open-circuit voltage (Voc of 1.59 V, short-circuit current density (Jsc of 7.96 mA/cm2, and a fill factor (FF of 0.70. After light-soaking test, our a-Si/a-Si tandem cell with p+ recombination layer shows the excellent stability and the stabilized efficiency of 8.7%.

  8. Drastic reduction in the surface recombination velocity of crystalline silicon passivated with catalytic chemical vapor deposited SiNx films by introducing phosphorous catalytic-doped layer

    International Nuclear Information System (INIS)

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

    2014-01-01

    We improve the passivation property of n-type crystalline silicon (c-Si) surface passivated with a catalytic chemical vapor deposited (Cat-CVD) Si nitride (SiN x ) film by inserting a phosphorous (P)-doped layer formed by exposing c-Si surface to P radicals generated by the catalytic cracking of PH 3 molecules (Cat-doping). An extremely low surface recombination velocity (SRV) of 2 cm/s can be achieved for 2.5 Ω cm n-type (100) floating-zone Si wafers passivated with SiN x /P Cat-doped layers, both prepared in Cat-CVD systems. Compared with the case of only SiN x passivated layers, SRV decreases from 5 cm/s to 2 cm/s. The decrease in SRV is the result of field effect created by activated P atoms (donors) in a shallow P Cat-doped layer. Annealing process plays an important role in improving the passivation quality of SiN x films. The outstanding results obtained imply that SiN x /P Cat-doped layers can be used as promising passivation layers in high-efficiency n-type c-Si solar cells.

  9. Non-radiative recombination process in BGaAs/GaAs alloys: Two layer photothermal deflection model

    Energy Technology Data Exchange (ETDEWEB)

    Ilahi, S., E-mail: ilehi_soufiene@yahoo.fr [Université de Carthage, Unité de Recherche de caractérisation photothermique et modélisation, Institut Préparatoire aux Etudes d’Ingénieurs de Nabeul (IPEIN), 8000 Merazka, Nabeul (Tunisia); Baira, M.; Saidi, F. [Université de Monastir, Laboratoire de Micro-Optoélectronique et Nanostructures, Faculté des Sciences de Monastir. Avenue de l’Environnement, Monastir 5019 (Tunisia); Yacoubi, N. [Université de Carthage, Unité de Recherche de caractérisation photothermique et modélisation, Institut Préparatoire aux Etudes d’Ingénieurs de Nabeul (IPEIN), 8000 Merazka, Nabeul (Tunisia); Auvray, L. [Laboratoire Multimateriaux et Interfaces, Université Claude Bernard Lyon I, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Maaref, H. [Université de Monastir, Laboratoire de Micro-Optoélectronique et Nanostructures, Faculté des Sciences de Monastir. Avenue de l’Environnement, Monastir 5019 (Tunisia)

    2013-12-25

    Highlights: •We have developed a two layer photothermal deflection model. •We have determined the electronic properties of BGaAs/GaAs alloys. •We have studied the boron effect in the electronic parameters. -- Abstract: Photo-thermal deflection technique PTD is used to study the nonradiative recombination process in BGaAs/GaAs alloy with boron composition of 3% and 8% grown by metal organic chemical vapor deposition (MOCVD). A two layer theoretical model has been developed taking into account both thermal and electronic contribution in the photothermal signal allowing to extract the electronic parameters namely electronic diffusivity, surface and interface recombination. It is found that the increase of boron composition alters the BGaAs epilayers transport properties.

  10. Further insight on recombination losses in the intrinsic layer of a-Si:H solar cells using computer modeling tools

    Science.gov (United States)

    Rubinelli, Francisco A.; Ramirez, Helena; Ruiz, Carlos M.; Schmidt, Javier A.

    2017-05-01

    Recombination losses of a-Si:H based p-i-n solar cells in the annealed state are analyzed with device computer modeling. Under AM1.5 illumination, the recombination rate in the intrinsic layer is shown to be controlled by a combination of losses through defect and tail states. The influence of the defect concentration on the characteristic parameters of a solar cell is analyzed. The impact on the light current-voltage characteristic curve of adopting very low free carrier mobilities and a high density of states at the band edge is explored under red and AM1.5 illumination. The distribution of trapped charge, electric field, and recombination loses inside the intrinsic layer is examined, and their influence on the solar cell performance is discussed. Solar cells with intrinsic layers deposited with and without hydrogen dilution are examined. It is found that the photocurrent at -2 V is not always a good approximation of the saturated reverse-bias photocurrent in a-Si:H p-i-n solar cells at room temperature. The importance of using realistic electrical parameters in solar cell simulations is emphasized.

  11. Study on the use of TiO2 passivation layer to reduce recombination losses in dye sensitized solar cells

    International Nuclear Information System (INIS)

    Eskander bin Samsudin, Adel; Mohamed, Norani Muti; Nayan, Nafarizal; Ali, Riyaz Ahmad Mohamed; Shariffuddin, Sharifah Amira Amir; Omar, Salwa

    2012-01-01

    A lot of research on various aspects of dye solar cells (DSC) has been carried out in order to improve efficiency. This paper analyzes the utilization of TiO 2 passivation layers of different thicknesses by improving the electron transport properties. Four different thicknesses of passivation layers namely 10, 20, 50 and 100 nm were deposited onto the working electrode using r.f sputtering. The electrodes were assembled into TiO 2 based DSC with active area of 1 cm 2 . The solar performance was investigated using 100 mW/cm 2 of AM 1.5 simulated sunlight from solar simulator. The kinetics of the solar cells was investigated using Electrochemical Impedance Spectroscopy (EIS) measurement and the spectral response was measured using Incident Photon to Electron Conversion (IPCE) measurement system. The highest efficiency was found for DSC with 20 nm passivation layer. DSCs with the passivation layer have open circuit voltage, V OC increased by 57 mV, their current density, J SC increased by 0.774 mA cm −2 compared to the one without the passivation layer. The quantum efficiency of the 20 nm passivation layer is the highest, peaking at the wavelength of 534 nm, resulting in the highest performance. All DSCs with the passivation layer recorded higher ratio of R BR /R T where R T is the diffusion resistance of the TiO 2 particles in the mesoscopic layer and R BR is the recombination resistance of the electron to the electrolyte. This implies that the recombination of the electrolyte I − 3 /3I − couple at the substrate/electrolyte interface has been effectively reduced resulting in an enhanced efficiency.

  12. Efficacy of In2S3 interfacial recombination barrier layer in PbS quantum-dot-sensitized solar cells

    International Nuclear Information System (INIS)

    Basit, Muhammad Abdul; Abbas, Muhammad Awais; Bang, Jin Ho; Park, Tae Joo

    2015-01-01

    In 2 S 3 interfacial recombination barrier layer (IBL) via successive ionic layer adsorption and reaction (SILAR) was successfully employed between PbS quantum dots and mesoporous TiO 2 in quantum-dot-sensitized solar cells (QDSSCs). In 2 S 3 IBL significantly increased the resistance against back electron transfer from TiO 2 , resulting an increment in the photocurrent density (J SC ) for the cell with single SILAR cycle of In 2 S 3 IBL. Further increase in the number of SILAR cycles of In 2 S 3 IBL deteriorated the J SC , whereas open-circuit voltage sustained the increasing trend. Therefore, an optimal photo-conversion efficiency of ∼2.2% was obtained for the cell with 2 SILAR cycles of In 2 S 3 IBL, which strategically reached a value of ∼2.70% after annealing (increased by 40% compared to the control cell without IBL). In 2 S 3 IBL not only improved the recombination resistance and electron life time of the cells, but it also enhanced the photostability of the cells. - Highlights: • In 2 S 3 interfacial recombination barrier layer was deposited on TiO 2 photoanode via SILAR process. • Resistance against back electron transfer from TiO 2 (recombination) increased notably. • Fabricated PbS-QDSSCs were characterized using IPCE, OCVD and EIS techniques. • In 2 S 3 IBL improved chemical capacitance, electron life time and photostability of modified cells. • 2In 2 S 3 IBL showed optimal performance, yielding 40% improvement in PCE after heat treatment.

  13. Optical and Electrical Characteristics of Graphene Double Layer Formed by a Double Transfer of Graphene Single Layers.

    Science.gov (United States)

    Kim, Young Jun; Bae, Gi Yoon; Chun, Sungwoo; Park, Wanjun

    2016-03-01

    We demonstrate formation of double layer graphene by means of a double transfer using two single graphene layers grown by a chemical vapor deposition method. It is observed that shiftiness and broadness in the double-resonance of Raman scattering are much weaker than those of bilayer graphene formed naturally. Transport characteristics examined from transmission line measurements and field effect transistors show the similar behavior with those of single layer graphene. It indicates that interlayer separation, in electrical view, is large enough to avoid correlation between layers for the double layer structure. It is also observed from a transistor with the double layer graphene that molecules adsorpted on two inner graphene surfaces in the double layered structure are isolated and conserved from ambient environment.

  14. Stability and erosion of melt layers formed during plasma disruptions

    International Nuclear Information System (INIS)

    Hassanein, A.M.

    1989-01-01

    Melting and vaporization of metallic reactor components such as the first wall and the limiter/divertor may be expected in fusion reactors due to the high energy deposition resulting from plasma instabilities occuring during both normal and off-normal operating conditions. Off-normal operating conditions result from plasma disruptions where the plasma losses confinement and dumps its energy on parts of reactor components. High heat flux may also result during normal operating conditions due to fluctuations in plasma edge conditions. Of particular significance is the stability and erosion of the resulting melt layer which directly impacts the total expected lifetime of the reactor. The loss of the melt layer during the disruption could have a serious impact on the required safe and economic operation of the reactor. A model is developed to describe the behavior of the melt layer during the time evolution of the disruption. The analysis is done parametrically for a range of disruption times, energy densities and various acting forces

  15. Recombinant SINEs are formed at high frequency during induced retrotransposition in vivo.

    Science.gov (United States)

    Yadav, Vijay Pal; Mandal, Prabhat Kumar; Bhattacharya, Alok; Bhattacharya, Sudha

    2012-05-22

    Non-long terminal repeat Retrotransposons are referred to as long interspersed nuclear elements (LINEs) and their non-autonomous partners are short interspersed nuclear elements (SINEs). It is believed that an active SINE copy, upon retrotransposition, generates near identical copies of itself, which subsequently accumulate mutations resulting in sequence polymorphism. Here we show that when a retrotransposition-competent cell line of the parasitic protist Entamoeba histolytica, transfected with a marked SINE copy, is induced to retrotranspose, >20% of the newly retrotransposed copies are neither identical to the marked SINE nor to the mobilized resident SINEs. Rather they are recombinants of resident SINEs and the marked SINE. They are a consequence of retrotransposition and not DNA recombination, as they are absent in cells not expressing the retrotransposition functions. This high-frequency recombination provides a new explanation for the existence of mosaic SINEs, which may impact on genetic analysis of SINE lineages, and measurement of phylogenetic distances.

  16. The importance of dye chemistry and TiCl4 surface treatment in the behavior of Al2O3 recombination barrier layers deposited by atomic layer deposition in solid-state dye-sensitized solar cells

    KAUST Repository

    Brennan, Thomas P.; Bakke, Jonathan R.; Ding, I-Kang; Hardin, Brian E.; Nguyen, William H.; Mondal, Rajib; Bailie, Colin D.; Margulis, George Y.; Hoke, Eric T.; Sellinger, Alan; McGehee, Michael D.; Bent, Stacey F.

    2012-01-01

    Atomic layer deposition (ALD) was used to fabricate Al 2O 3 recombination barriers in solid-state dye-sensitized solar cells (ss-DSSCs) employing an organic hole transport material (HTM) for the first time. Al 2O 3 recombination barriers of varying

  17. Wearable electronics formed on intermediate layer on textiles

    KAUST Repository

    Hussain, Muhammad Mustafa

    2017-07-27

    One manner of producing more desirable clothing with electronic capabilities is to manufacture electronics, such as the charging wires or devices themselves, directly onto the textile materials. Textile materials generally do not support the manufacturing of electronic devices, in part because the surface of the textile is too rough for electronic devices or the processes used to manufacturing electronic devices. An intermediate layer (204) may be placed on the textile material (202) to reduce the roughness of the surface of the textile material and provide other beneficial characteristics for the placement of electronic devices (206) directly on the textile material.

  18. Earth's magnetosphere formed by the low-latitude boundary layer

    CERN Document Server

    Heikkila, W J

    2011-01-01

    The author argues that, after five decades of debate about the interactive of solar wind with the magnetosphere, it is time to get back to basics. Starting with Newton's law, this book also examines Maxwell's equations and subsidiary equations such as continuity, constitutive relations and the Lorentz transformation; Helmholtz' theorem, and Poynting's theorem, among other methods for understanding this interaction. Includes chapters on prompt particle acceleration to high energies, plasma transfer event, and the low latitude boundary layer More than 200 figures illustrate the text Includes a color insert.

  19. Genetic Characterization of a Novel HIV-1 Circulating Recombinant Form (CRF74_01B) Identified among Intravenous Drug Users in Malaysia: Recombination History and Phylogenetic Linkage with Previously Defined Recombinant Lineages.

    Science.gov (United States)

    Cheong, Hui Ting; Chow, Wei Zhen; Takebe, Yutaka; Chook, Jack Bee; Chan, Kok Gan; Al-Darraji, Haider Abdulrazzaq Abed; Koh, Clayton; Kamarulzaman, Adeeba; Tee, Kok Keng

    2015-01-01

    In many parts of Southeast Asia, the HIV-1 epidemic has been driven by the sharing of needles and equipment among intravenous drug users (IDUs). Over the last few decades, many studies have proven time and again that the diversity of HIV-1 epidemics can often be linked to the route of infection transmission. That said, the diversity and complexity of HIV-1 molecular epidemics in the region have been increasing at an alarming rate, due in part to the high tendency of the viral RNA to recombine. This scenario was exemplified by the discovery of numerous circulating recombinant forms (CRFs), especially in Thailand and Malaysia. In this study, we characterized a novel CRF designated CRF74_01B, which was identified in six epidemiologically unlinked IDUs in Kuala Lumpur, Malaysia. The near-full length genomes were composed of CRF01_AE and subtype B', with eight breakpoints dispersed in the gag-pol and nef regions. Remarkably, this CRF shared four and two recombination hotspots with the previously described CRF33_01B and the less prevalent CRF53_01B, respectively. Genealogy-based Bayesian phylogenetic analysis of CRF74_01B genomic regions showed that it is closely related to both CRF33_01B and CRF53_01B. This observation suggests that CRF74_01B was probably a direct descendent from specific lineages of CRF33_01B, CRF53_01B and subtype B' that could have emerged in the mid-1990s. Additionally, it illustrated the active recombination processes between prevalent HIV-1 subtypes and recombinants in Malaysia. In summary, we report a novel HIV-1 genotype designated CRF74_01B among IDUs in Kuala Lumpur, Malaysia. The characterization of the novel CRF74_01B is of considerable significance towards the understanding of the genetic diversity and population dynamics of HIV-1 circulating in the region.

  20. Genetic Characterization of a Novel HIV-1 Circulating Recombinant Form (CRF74_01B Identified among Intravenous Drug Users in Malaysia: Recombination History and Phylogenetic Linkage with Previously Defined Recombinant Lineages.

    Directory of Open Access Journals (Sweden)

    Hui Ting Cheong

    Full Text Available In many parts of Southeast Asia, the HIV-1 epidemic has been driven by the sharing of needles and equipment among intravenous drug users (IDUs. Over the last few decades, many studies have proven time and again that the diversity of HIV-1 epidemics can often be linked to the route of infection transmission. That said, the diversity and complexity of HIV-1 molecular epidemics in the region have been increasing at an alarming rate, due in part to the high tendency of the viral RNA to recombine. This scenario was exemplified by the discovery of numerous circulating recombinant forms (CRFs, especially in Thailand and Malaysia. In this study, we characterized a novel CRF designated CRF74_01B, which was identified in six epidemiologically unlinked IDUs in Kuala Lumpur, Malaysia. The near-full length genomes were composed of CRF01_AE and subtype B', with eight breakpoints dispersed in the gag-pol and nef regions. Remarkably, this CRF shared four and two recombination hotspots with the previously described CRF33_01B and the less prevalent CRF53_01B, respectively. Genealogy-based Bayesian phylogenetic analysis of CRF74_01B genomic regions showed that it is closely related to both CRF33_01B and CRF53_01B. This observation suggests that CRF74_01B was probably a direct descendent from specific lineages of CRF33_01B, CRF53_01B and subtype B' that could have emerged in the mid-1990s. Additionally, it illustrated the active recombination processes between prevalent HIV-1 subtypes and recombinants in Malaysia. In summary, we report a novel HIV-1 genotype designated CRF74_01B among IDUs in Kuala Lumpur, Malaysia. The characterization of the novel CRF74_01B is of considerable significance towards the understanding of the genetic diversity and population dynamics of HIV-1 circulating in the region.

  1. Linked Data: Forming Partnerships at the Data Layer

    Science.gov (United States)

    Shepherd, A.; Chandler, C. L.; Arko, R. A.; Jones, M. B.; Hitzler, P.; Janowicz, K.; Krisnadhi, A.; Schildhauer, M.; Fils, D.; Narock, T.; Groman, R. C.; O'Brien, M.; Patton, E. W.; Kinkade, D.; Rauch, S.

    2015-12-01

    The challenges presented by big data are straining data management software architectures of the past. For smaller existing data facilities, the technical refactoring of software layers become costly to scale across the big data landscape. In response to these challenges, data facilities will need partnerships with external entities for improved solutions to perform tasks such as data cataloging, discovery and reuse, and data integration and processing with provenance. At its surface, the concept of linked open data suggests an uncalculated altruism. Yet, in his concept of five star open data, Tim Berners-Lee explains the strategic costs and benefits of deploying linked open data from the perspective of its consumer and producer - a data partnership. The Biological and Chemical Oceanography Data Management Office (BCO-DMO) addresses some of the emerging needs of its research community by partnering with groups doing complementary work and linking their respective data layers using linked open data principles. Examples will show how these links, explicit manifestations of partnerships, reduce technical debt and provide a swift flexibility for future considerations.

  2. Pressing of three-layer, dry-formed MDF with binderless hardboard faces

    Science.gov (United States)

    Otto Suchsland; George E. Woodson; Charles W. McMillin

    1986-01-01

    Severely cooked Masonite pulp was used as face material in three-layer experimental medium-density fiberboard (MDF). The core layer consisted of conventional MDF furnish with resin binder added. The faces were formed absolutely dry without additives of any kind. The three-layer mat was hot-pressed to overall densities ranging from 44 to 56 pcf. The faces had hardboard-...

  3. On the surface recombination current of metal-insulator semiconductor inversion layer solar cells

    DEFF Research Database (Denmark)

    Nielsen, Otto M.

    1981-01-01

    voltages Voc were found to be lower than for ~ cells. The measured differences in Voc were higher than expected from the dark characteristics which is explained as a difference in the surface recombination current due to a higher interface state density Nss of ~ cells. Journal of Applied Physics...

  4. Deposited Micro Porous Layer as Lubricant Carrier in Metal Forming

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Bay, Niels; Tang, Peter Torben

    2008-01-01

    as lubricant reservoirs. Conventional friction tests for cold forming; ring compression and double cup extrusion tests are carried out with Molykote DX paste and mineral oil as lubricant. Both lubricants act as intended for the ring compressions test whereas only the low viscosity oil perform successfully...... in the cup extrusion test. For all specimens without the porous coating, high friction conditions are identified....

  5. Zinc tin oxide as high-temperature stable recombination layer for mesoscopic perovskite/silicon monolithic tandem solar cells

    KAUST Repository

    Werner, Jérémie

    2016-12-05

    Perovskite/crystalline silicon tandem solar cells have the potential to reach efficiencies beyond those of silicon single-junction record devices. However, the high-temperature process of 500 °C needed for state-of-the-art mesoscopic perovskite cells has, so far, been limiting their implementation in monolithic tandem devices. Here, we demonstrate the applicability of zinc tin oxide as a recombination layer and show its electrical and optical stability at temperatures up to 500 °C. To prove the concept, we fabricate monolithic tandem cells with mesoscopic top cell with up to 16% efficiency. We then investigate the effect of zinc tin oxide layer thickness variation, showing a strong influence on the optical interference pattern within the tandem device. Finally, we discuss the perspective of mesoscopic perovskite cells for high-efficiency monolithic tandem solar cells. © 2016 Author(s)

  6. Turbine airfoil with dual wall formed from inner and outer layers separated by a compliant structure

    Science.gov (United States)

    Campbell,; Christian X. , Morrison; Jay, A [Oviedo, FL

    2011-12-20

    A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a compliant structure. The compliant structure may be configured such that the outer layer may thermally expand without limitation by the inner layer. The compliant structure may be formed from a plurality of pedestals positioned generally parallel with each other. The pedestals may include a first foot attached to a first end of the pedestal and extending in a first direction aligned with the outer layer, and may include a second foot attached to a second end of the pedestal and extending in a second direction aligned with the inner layer.

  7. Comparative assessment of recombinant and native immunogenic forms of Fasciola hepatica proteins for serodiagnosis of sheep fasciolosis.

    Science.gov (United States)

    Mokhtarian, Kobra; Meamar, Ahmad Reza; Khoshmirsafa, Majid; Razmjou, Elham; Masoori, Leila; Khanmohammadi, Majid; Akhlaghi, Lame; Falak, Reza

    2018-01-01

    Laboratory diagnosis of sheep fasciolosis is commonly performed by coprological examinations; however, this method may lead to false negative results during the acute phase of the infection. Furthermore, the poor sensitivity of coprological methods is considered to be a paradox in the chronic phase of the infection. In this study, we compared the immunoreactivity of native and recombinant forms of Fasciola hepatica excretory/secretory antigens and determined their capabilities for the development of F. hepatica-specific immunoassays. Immunoreactivity and specificity of recombinant and native forms of F. hepatica antigens, including fatty acid binding protein (FABP), glutathione-S-transferase (GST), and cathepsin L-1 (CL1), in parallel with native forms of FABP and GST, were studied for serodiagnosis of the chronic form of sheep fasciolosis, individually or in combination with each other by enzyme-linked immunosorbent assays (ELISA). The correlation of the findings was assessed by receiver-operator characteristic (ROC); furthermore, the specificity and sensitivity were assessed by Youden's J. Serologic cross-reactivity was evaluated using samples from healthy sheep (n = 40), Fasciola-infected sheep (n = 30), and sheep with other parasitic infections (n = 43). The FABPs were determined to be greater than 95% sensitive for F. hepatica serodiagnosis. The most desirable diagnostic recombinant antigen was rCL1, which showed 100% sensitivity and 97% specificity in ELISA and was capable of discriminating the positive and negative samples by maximum Youden's J results. We conclude that rCL1 can be used for routine serodiagnosis of chronic fasciolosis. Thus, it could be advantageous in development of immunoassays for screening of ovine herds in fasciolosis-endemic areas and as a reliable agent for detection of fasciolosis in non-endemic regions.

  8. Process for forming epitaxial perovskite thin film layers using halide precursors

    Science.gov (United States)

    Clem, Paul G.; Rodriguez, Mark A.; Voigt, James A.; Ashley, Carol S.

    2001-01-01

    A process for forming an epitaxial perovskite-phase thin film on a substrate. This thin film can act as a buffer layer between a Ni substrate and a YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor layer. The process utilizes alkali or alkaline metal acetates dissolved in halogenated organic acid along with titanium isopropoxide to dip or spin-coat the substrate which is then heated to about 700.degree. C. in an inert gas atmosphere to form the epitaxial film on the substrate. The YBCO superconductor can then be deposited on the layer formed by this invention.

  9. XPS study of the passive layers formed on lead in aqueous nitrate solutions

    International Nuclear Information System (INIS)

    Uchida, Miho; Okuwaki, Akitsugu

    1997-01-01

    The analysis of the lead surface immersed in aqueous nitrate solutions by X-ray photoelectron spectroscopy (XPS) shows the formation of passive oxide layer containing nitrogen compound. The oxide layer formed on the lead surface in aqueous ammonium nitrate solution was hydrolyzed and cracked. (author)

  10. Efficient and Air-Stable Planar Perovskite Solar Cells Formed on Graphene-Oxide-Modified PEDOT:PSS Hole Transport Layer

    Science.gov (United States)

    Luo, Hui; Lin, Xuanhuai; Hou, Xian; Pan, Likun; Huang, Sumei; Chen, Xiaohong

    2017-10-01

    As a hole transport layer, PEDOT:PSS usually limits the stability and efficiency of perovskite solar cells (PSCs) due to its hygroscopic nature and inability to block electrons. Here, a graphene-oxide (GO)-modified PEDOT:PSS hole transport layer was fabricated by spin-coating a GO solution onto the PEDOT:PSS surface. PSCs fabricated on a GO-modified PEDOT:PSS layer exhibited a power conversion efficiency (PCE) of 15.34%, which is higher than 11.90% of PSCs with the PEDOT:PSS layer. Furthermore, the stability of the PSCs was significantly improved, with the PCE remaining at 83.5% of the initial PCE values after aging for 39 days in air. The hygroscopic PSS material at the PEDOT:PSS surface was partly removed during spin-coating with the GO solution, which improves the moisture resistance and decreases the contact barrier between the hole transport layer and perovskite layer. The scattered distribution of the GO at the PEDOT:PSS surface exhibits superior wettability, which helps to form a high-quality perovskite layer with better crystallinity and fewer pin holes. Furthermore, the hole extraction selectivity of the GO further inhibits the carrier recombination at the interface between the perovskite and PEDOT:PSS layers. Therefore, the cooperative interactions of these factors greatly improve the light absorption of the perovskite layer, the carrier transport and collection abilities of the PSCs, and especially the stability of the cells.

  11. Ion implantation into amorphous Si layers to form carrier-selective contacts for Si solar cells

    International Nuclear Information System (INIS)

    Feldmann, Frank; Mueller, Ralph; Reichel, Christian; Hermle, Martin

    2014-01-01

    This paper reports our findings on the boron and phosphorus doping of very thin amorphous silicon layers by low energy ion implantation. These doped layers are implemented into a so-called tunnel oxide passivated contact structure for Si solar cells. They act as carrier-selective contacts and, thereby, lead to a significant reduction of the cell's recombination current. In this paper we address the influence of ion energy and ion dose in conjunction with the obligatory high-temperature anneal needed for the realization of the passivation quality of the carrier-selective contacts. The good results on the phosphorus-doped (implied V oc = 725 mV) and boron-doped passivated contacts (iV oc = 694 mV) open a promising route to a simplified interdigitated back contact (IBC) solar cell featuring passivated contacts. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Hydrogen gas driven permeation through tungsten deposition layer formed by hydrogen plasma sputtering

    International Nuclear Information System (INIS)

    Uehara, Keiichiro; Katayama, Kazunari; Date, Hiroyuki; Fukada, Satoshi

    2015-01-01

    Highlights: • H permeation tests for W layer formed by H plasma sputtering are performed. • H permeation flux through W layer is larger than that through W bulk. • H diffusivity in W layer is smaller than that in W bulk. • The equilibrium H concentration in W layer is larger than that in W bulk. - Abstract: It is important to evaluate the influence of deposition layers formed on plasma facing wall on tritium permeation and tritium retention in the vessel of a fusion reactor from a viewpoint of safety. In this work, tungsten deposition layers having different thickness and porosity were formed on circular nickel plates by hydrogen RF plasma sputtering. Hydrogen permeation experiment was carried out at the temperature range from 250 °C to 500 °C and at hydrogen pressure range from 1013 Pa to 101,300 Pa. The hydrogen permeation flux through the nickel plate with tungsten deposition layer was significantly smaller than that through a bare nickel plate. This indicates that a rate-controlling step in hydrogen permeation was not permeation through the nickel plate but permeation though the deposition layer. The pressure dependence on the permeation flux differed by temperature. Hydrogen permeation flux through tungsten deposition layer is larger than that through tungsten bulk. From analysis of the permeation curves, it was indicated that hydrogen diffusivity in tungsten deposition layer is smaller than that in tungsten bulk and the equilibrium hydrogen concentration in tungsten deposition layer is enormously larger than that in tungsten bulk at same hydrogen pressure.

  13. Fast and easy protocol for the purification of recombinant S-layer protein for synthetic biology applications

    KAUST Repository

    Norville, Julie E.; Kelly, Deborah F.; Knight, Thomas F.; Belcher, Angela M.; Walz, Thomas

    2011-01-01

    A goal of synthetic biology is to make biological systems easier to engineer. One of the aims is to design, with nanometer-scale precision, biomaterials with well-defined properties. The surface-layer protein SbpA forms 2D arrays naturally

  14. Glycan microarray analysis of the carbohydrate-recognition specificity of native and recombinant forms of the lectin ArtinM.

    Science.gov (United States)

    Liu, Y; Cecílio, N T; Carvalho, F C; Roque-Barreira, M C; Feizi, T

    2015-12-01

    This article contains data related to the researc.h article entitled "Yeast-derived ArtinM shares structure, carbohydrate recognition, and biological effects with native ArtinM" by Cecílio et al. (2015) [1]. ArtinM, a D-mannose-binding lectin isolated from the seeds of Artocarpus heterophyllus, exerts immunomodulatory and regenerative activities through its Carbohydrate Recognition Domain (CRD) (Souza et al., 2013; Mariano et al., 2014 [2], [3]). The limited availability of the native lectin (n-ArtinM) led us to characterize a recombinant form of the protein, obtained by expression in Saccharomyces cerevisiae (y-ArtinM). We compared the carbohydrate-binding specificities of y-ArtinM and n-ArtinM by analyzing the binding of biotinylated preparations of the two lectin forms using a neoglycolipid (NGL)-based glycan microarray. Data showed that y-ArtinM mirrored the specificity exhibited by n-ArtinM.

  15. INTERACTION BETWEEN DIFFERENT MOLECULAR FORMS OF IMMUNOGLOBULIN A AND RECOMBINANT DERIVATIVES POLYPEPTIDES OF BAC RECEPTOR PROTEINS FROM GROUP B STREPTOCOCCI

    Directory of Open Access Journals (Sweden)

    A. S. Korzhueva

    2008-01-01

    Full Text Available Abstract. The article concerns interactions between immunoglobulin A and recombinant P6, P7, P8 polypeptides, designed on the basis of externally localized Bac protein of the Group B streptococci, possessing IgA-binding activity.There is a current demand for immunochemical reagents that are strictly specific for IgA, in order to develop antigenic standards for detection of IgA levels in biological fluids, as well as for affinity purification of IgA and its fragments.To analyze an opportunity of the abovementioned application ways for these proteins, a special study was performed to assay an interaction capability of recombinant P6, P7, P8 polypeptides binding to Fc regions of different IgA forms (serum IgA, secretory IgA, subclasses of serum IgA – IgA1, IgA2. Selectivity of ligand binding was specially confirmed.It was found out that, among three presented polypeptides, the structure of recombinant P6 derivative proved to be optimal for IgA-binding ability of Bac protein.Structural features of IgA-binding fragments of Bac protein, i.e., binding site position on the IgA molecule (proximity to epitopes for three monoclonal antibodies, variability of the site structure, as well as resistance of binding site for P6, P7, P8 in IgA molecule against partial disulfide bonds reduction. (Med. Immunol., vol. 10, N 4-5, pp 327-336.

  16. Kosmotropic anions promote conversion of recombinant prion protein into a PrPSc-like misfolded form.

    Directory of Open Access Journals (Sweden)

    Rodrigo Diaz-Espinoza

    Full Text Available Prions are self-propagating proteins involved in transmissible spongiform encephalopaties in mammals. An aberrant conformation with amyloid-like features of a cell surface protein, termed prion protein (PrP, is thought to be the essential component of the infectious particle, though accessory co-factor molecules such as lipids and nucleotides may be involved. The cellular co-factors and environmental conditions implicated in PrP misfolding are not completely understood. To address this issue, several studies have been done inducing misfolding of recombinant PrP (recPrP into classical amyloid structures using partially denaturing conditions. In this work, we report that misfolding of recPrP into PrP(Sc-like aggregates can be induced by simply incubating the protein in the presence of kosmotropic salts at concentrations that are known to retain or increase the stability of the protein. We used a simple experimental reaction (protein, buffer and salts submitted to agitation/incubation cycles at physiological temperature and pH. The formation of protease resistant-recPrP was time and salt-concentration dependent and required the presence of kosmotropic anions such as F(- or SO(4(-2. The molecular weights of the protease resistant recPrP fragments are reminiscent of those found in degradation assays of bona fide PrP(Sc. The aggregates also exhibited PrP(Sc-like ultrastructural features including rod-shape morphology under electron microscope, high beta-sheet content and thioflavin-T positive signal. The formation of recPrP aggregates with PrP(Sc biochemical features under conditions closer to physiological in the absence of organic co-factor molecules provides a simple setup that may prove helpful to understand the molecular mechanism of PrP misfolding.

  17. Compressibility of the fouling layer formed by membrane bioreactor sludge and supernatant

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Poorasgari, Eskandar; Christensen, Morten Lykkegaard

    Membrane bioreactors (MBR) are increasingly used for wastewater treatment as they give high effluent quality, low footprint and efficient sludge degradation. However, the accumulation and deposition of sludge components on and within the membrane (fouling) limits the widespread application of MBR....... Compressibility of the gel layer was studied in a dead-end filtration system, whereas the compressibility of a fouling layer formed by MBR sludge was studied in a submerged system hollow sheet membrane by TMP stepping. It was shown that the fouling layer formed by the MBR sludge was highly compressible within....... Hence, for MBR systems operated at constant flux mode, the applied pressure should be increased over time, to compensate for the lower permeability. Increasing applied pressure causes compression of the fouling layer and results in a more severe permeability decline [1]. In a general view, the fouling...

  18. XPS studies of SiO2 surface layers formed by oxygen ion implantation into silicon

    International Nuclear Information System (INIS)

    Schulze, D.; Finster, J.

    1983-01-01

    SiO 2 surface layers of 160 nm thickness formed by 16 O + ion implantation into silicon are examined by X-ray photoelectron spectroscopy measurements into the depth after a step-by-step chemical etching. The chemical nature and the thickness of the transition layer were determined. The results of the XPS measurements show that the outer surface and the bulk of the layers formed by oxygen implantation and subsequent high temperature annealing consist of SiO 2 . There is no evidence for Si or SiO/sub x/ (0 2 and Si is similar to that of thin grown oxide layers. Only its thickness is somewhat larger than in thermal oxide

  19. Novel HIV-1 recombinants spreading across multiple risk groups in the United Kingdom: the identification and phylogeography of Circulating Recombinant Form (CRF 50_A1D.

    Directory of Open Access Journals (Sweden)

    Geraldine M Foster

    Full Text Available An increase in non-B HIV-1 infections among men who have sex with men (MSM in the United Kingdom (UK has created opportunities for novel recombinants to arise and become established. We used molecular mapping to characterize the importance of such recombinants to the UK HIV epidemic, in order to gain insights into transmission dynamics that can inform control strategies.A total of 55,556 pol (reverse transcriptase and protease sequences in the UK HIV Drug Resistance Database were analyzed using Subtype Classification Using Evolutionary Algorithms (SCUEAL. Overall 72 patients shared the same A1/D recombination breakpoint in pol, comprising predominantly MSM but also heterosexuals and injecting drug users (IDUs. In six MSM, full-length single genome amplification of plasma HIV-1 RNA was performed in order to characterize the A1/D recombinant. Subtypes and recombination breakpoints were identified using sliding window and jumping profile hidden markov model approaches. Global maximum likelihood trees of gag, pol and env genes were drawn using FastTree version 2.1. Five of the six strains showed the same novel A1/D recombinant (8 breakpoints, which has been classified as CRF50_A1D. The sixth strain showed a complex CRF50_A1D/B/U structure. Divergence dates and phylogeographic inferences were determined using Bayesian Evolutionary Analysis using Sampling Trees (BEAST. This estimated that CRF50_A1D emerged in the UK around 1992 in MSM, with subsequent transmissions to heterosexuals and IDUs. Analysis of CRF50_A1D/B/U demonstrated that around the year 2000 CRF50_A1D underwent recombination with a subtype B strain.We report the identification of CRF50_A1D, a novel circulating recombinant that emerged in UK MSM around 1992, with subsequent onward transmission to heterosexuals and IDUs, and more recent recombination with subtype B. These findings highlight the changing dynamics of HIV transmission in the UK and the converging of the two previously

  20. Gas recombination assembly for electrochemical cells

    Science.gov (United States)

    Levy, Isaac; Charkey, Allen

    1989-01-01

    An assembly for recombining gases generated in electrochemical cells wherein a catalyst strip is enveloped within a hydrophobic, gas-porous film which, in turn, is encased between gas-porous, metallic layers. The sandwich construction of metallic layers and film is formed into a spiral with a tab for connection to the cell.

  1. A Strategy to Enhance the Efficiency of Quantum Dot-Sensitized Solar Cells by Decreasing Electron Recombination with Polyoxometalate/TiO2 as the Electronic Interface Layer.

    Science.gov (United States)

    Chen, Li; Chen, Weilin; Li, Jianping; Wang, Jiabo; Wang, Enbo

    2017-07-21

    Electron recombination occurring at the TiO 2 /quantum dot sensitizer/electrolyte interface is the key reason for hindering further efficiency improvements to quantum dot sensitized solar cells (QDSCs). Polyoxometalate (POM) can act as an electron-transfer medium to decrease electron recombination in a photoelectric device owing to its excellent oxidation/reduction properties and thermostability. A POM/TiO 2 electronic interface layer prepared by a simple layer-by-layer self-assembly method was added between fluorine-doped tin oxide (FTO) and mesoporous TiO 2 in the photoanode of QDSCs, and the effect on the photovoltaic performance was systematically investigated. Photovoltaic experimental results and the electron transmission mechanism show that the POM/TiO 2 electronic interface layer in the QDSCs can clearly suppress electron recombination, increase the electron lifetime, and result in smoother electron transmission. In summary, the best conversion efficiency of QDSCs with POM/TiO 2 electronic interface layers increases to 8.02 %, which is an improvement of 25.1 % compared with QDSCs without POM/TiO 2 . This work first builds an electron-transfer bridge between FTO and the quantum dot sensitizer and paves the way for further improved efficiency of QDSCs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effects of emission layer doping on the spatial distribution of charge and host recombination rate density in organic light emitting devices: A numerical study

    Science.gov (United States)

    Li, Yanli; Zhou, Maoqing; Zheng, Tingcai; Yao, Bo; Peng, Yingquan

    2013-12-01

    Based on drift-diffusion theory, a numerical model of the doping of a single energy level trap in the emission layer of an organic light emitting device (OLED) was developed, and the effects of doping of this single energy level trap on the distribution of the charge density, the recombination rate density, and the electric field in single- and double-layer OLEDs were studied numerically. The results show that by doping the n-type (p-type) emission layer with single energy electron (hole) traps, the distribution of the recombination rate density can be tuned and shifted, which is useful for improvement of the device performance by reduced electrode quenching or for realization of desirable special functions, e.g., emission spectrum tuning in multiple dye-doped white OLEDs.

  3. Effects of emission layer doping on the spatial distribution of charge and host recombination rate density in organic light emitting devices: A numerical study

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yanli; Zhou, Maoqing; Zheng, Tingcai; Yao, Bo [Institute of Microelectronics, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Peng, Yingquan, E-mail: yqpeng@lzu.edu.cn [Institute of Microelectronics, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2013-12-28

    Based on drift-diffusion theory, a numerical model of the doping of a single energy level trap in the emission layer of an organic light emitting device (OLED) was developed, and the effects of doping of this single energy level trap on the distribution of the charge density, the recombination rate density, and the electric field in single- and double-layer OLEDs were studied numerically. The results show that by doping the n-type (p-type) emission layer with single energy electron (hole) traps, the distribution of the recombination rate density can be tuned and shifted, which is useful for improvement of the device performance by reduced electrode quenching or for realization of desirable special functions, e.g., emission spectrum tuning in multiple dye-doped white OLEDs.

  4. Effects of emission layer doping on the spatial distribution of charge and host recombination rate density in organic light emitting devices: A numerical study

    International Nuclear Information System (INIS)

    Li, Yanli; Zhou, Maoqing; Zheng, Tingcai; Yao, Bo; Peng, Yingquan

    2013-01-01

    Based on drift-diffusion theory, a numerical model of the doping of a single energy level trap in the emission layer of an organic light emitting device (OLED) was developed, and the effects of doping of this single energy level trap on the distribution of the charge density, the recombination rate density, and the electric field in single- and double-layer OLEDs were studied numerically. The results show that by doping the n-type (p-type) emission layer with single energy electron (hole) traps, the distribution of the recombination rate density can be tuned and shifted, which is useful for improvement of the device performance by reduced electrode quenching or for realization of desirable special functions, e.g., emission spectrum tuning in multiple dye-doped white OLEDs

  5. Heterologous expression of a truncated form of human recombinant vascular endothelial growth factor-A and its biological activity in wound healing.

    Science.gov (United States)

    Khaki, Mohsen; Salmanian, Ali Hatef; Mosayebi, Ghasem; Baazm, Maryam; Babaei, Saeed; Molaee, Neda; Abtahi, Hamid

    2017-07-01

    Vascular endothelial growth factor (VEGF) is one of the most effective proteins in angiogenesis, mesenchymal stem cells (MSCs) differentiation and wound healing. These abilities are therapeutic potential of VEGF in diabetic retinopathy, nephropathy and other tissue damage circumstances. In this study, recombinant VEGF was produced in Escherichia coli ( E. coli ) system and then biological activity of this protein was evaluated in animal wound healing. E. coli BL21 (DE3) competent cells were transformed with pET32a-VEGF clone and induced by isopropyl-β-D-thio-galactoside (IPTG). The recombinant protein was purified by affinity chromatography. Recombinant VEGF-A-based ointment (VEGF/Vaseline 0.8 mg/100 w/w) was used for external wound (25×15mm thickness) healing in animal model. In vivo activity of ointment was evaluated by clinical evidences and cytological microscopic assessment. The recombinant protein with molecular weight of 45 kilodaltons (kDa) and concentration of 0.8 mg/ml was produced. Immunoblotting data showed that the antigenic region of VEGF can be expressed in E. coli and the recombinant protein has similar epitopes with close antigenic properties to the natural form. Macroscopic findings and microscopic data showed that the recombinant VEGF-A ointment was effective on excisional wound healing. Recombinant VEGF-A produced by pET32a in E. coli , possesses acceptable structure and has wound healing capability.

  6. Heterologous expression of a truncated form of human recombinant vascular endothelial growth factor-A and its biological activity in wound healing

    Directory of Open Access Journals (Sweden)

    Mohsen Khaki

    2017-07-01

    Full Text Available Objective(s: Vascular endothelial growth factor (VEGF is one of the most effective proteins in angiogenesis, mesenchymal stem cells (MSCs differentiation and wound healing. These abilities are therapeutic potential of VEGF in diabetic retinopathy, nephropathy and other tissue damage circumstances. In this study, recombinant VEGF was produced in Escherichia coli (E. coli system and then biological activity of this protein was evaluated in animal wound healing. Materials and Methods: E. coli BL21 (DE3 competent cells were transformed with pET32a-VEGF clone and induced by isopropyl-β-D-thio-galactoside (IPTG. The recombinant protein was purified byaffinity chromatography. Recombinant VEGF-A-based ointment (VEGF/Vaseline 0.8 mg/100 w/w was used for external wound (25×15mm thickness healing in animal model. In vivo activity of ointment was evaluated by clinical evidences and cytological microscopic assessment. Results: The recombinant protein with molecular weight of 45 kilodaltons (kDa and concentration of 0.8 mg/ml was produced.Immunoblotting data showed that the antigenic region of VEGF can be expressed in E. coli and the recombinant protein has similar epitopes with close antigenic properties to the natural form. Macroscopic findings and microscopic data showed that the recombinant VEGF-A ointment was effective on excisional wound healing. Conclusion: Recombinant VEGF-A produced by pET32a in E. coli, possesses acceptable structure and has wound healing capability.

  7. Analysis of white layers formed in hard turning of AISI 52100 steel

    International Nuclear Information System (INIS)

    Ramesh, A.; Melkote, S.N.; Allard, L.F.; Riester, L.; Watkins, T.R.

    2005-01-01

    The formation mechanisms and properties of white layers produced in machining of hardened steels are not clearly understood to date. In particular, detailed analysis of their structure and mechanical properties is lacking. This paper investigates the differences in structure and properties of white layers formed during machining of hardened AISI 52100 steel (62 HRC) at different cutting speeds. A combination of experimental techniques including transmission electron microscopy (TEM), X-ray diffraction (XRD), and nano-indentation are used to analyze the white layers formed. TEM results suggest that white layers produced at low-to-moderate cutting speeds are in large part due to grain refinement induced by severe plastic deformation, whereas white layer formation at high cutting speeds is mainly due to thermally-driven phase transformation. The white layers at all speeds are found to be comprised of very fine (nano-scale) grains compared to the bulk material. XRD-based residual stress and retained austenite measurements, and hardness data support these findings

  8. Corrosion resistance of modified layer on uranium formed by plasma immersion ion implantation

    International Nuclear Information System (INIS)

    Long Zhong; Liu Kezhao; Bai Bin; Yan Dongxu

    2010-01-01

    Nitrogen ion was implanted into uranium surface using plasma immersion ion implantation, and the corrosion resistance of modified layer was studied by corrosion experiment. SEM was used to observe variety of samples surface. In atmosphere, the sample surface had not changed during five months. In heat-humid environment, there was dot-corrosion appearing after two months, but it did not influence the integrity of the modified layer. AES was used to study the diffusion of oxygen and nitrogen during hot-humid corrosion, in three months, both of two elements diffused to the substrate, but the diffusion was weak. The structure of modified layer was not changed. Experimental results show that the modified layer formed by plasma immersion ion implantation has good corrosion resistance.

  9. Corrosion resistance of modified layer on uranium formed by plasma immersion ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Long Zhong, E-mail: long2001@163.co [China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Liu Kezhao; Bai Bin; Yan Dongxu [China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China)

    2010-02-18

    Nitrogen ion was implanted into uranium surface using plasma immersion ion implantation, and the corrosion resistance of modified layer was studied by corrosion experiment. SEM was used to observe variety of samples surface. In atmosphere, the sample surface had not changed during five months. In heat-humid environment, there was dot-corrosion appearing after two months, but it did not influence the integrity of the modified layer. AES was used to study the diffusion of oxygen and nitrogen during hot-humid corrosion, in three months, both of two elements diffused to the substrate, but the diffusion was weak. The structure of modified layer was not changed. Experimental results show that the modified layer formed by plasma immersion ion implantation has good corrosion resistance.

  10. Hydrogen retention in carbon-tungsten co-deposition layer formed by hydrogen RF plasma

    International Nuclear Information System (INIS)

    Katayama, K.; Kawasaki, T.; Manabe, Y.; Nagase, H.; Takeishi, T.; Nishikawa, M.

    2006-01-01

    Carbon-tungsten co-deposition layers (C-W layers) were formed by sputtering method using hydrogen or deuterium RF plasma. The deposition rate of the C-W layer by deuterium plasma was faster than that by hydrogen plasma, where the increase of deposition rate of tungsten was larger than that of carbon. This indicates that the isotope effect on sputtering-depositing process for tungsten is larger than that for carbon. The release curve of hydrogen from the C-W layer showed two peaks at 400 deg. C and 700 deg. C. Comparing the hydrogen release from the carbon deposition layer and the tungsten deposition layer, it is considered that the increase of the release rate at 400 deg. C is affected by tungsten and that at 700 deg. C is affected by carbon. The obtained hydrogen retention in the C-W layers which have over 60 at.% of carbon was in the range between 0.45 and 0.16 as H/(C + W)

  11. Etch-stop behavior of buried layers formed by substoichiometric nitrogen ion implantation into silicon

    International Nuclear Information System (INIS)

    Perez-Rodriguez, A.; Romano-Rodriguez, A.; Morante, J.R.; Acero, M.C. Esteve, J.; Montserrat, J.; El-Hassani, A.

    1996-01-01

    In this work the etch-stop behavior of buried layers formed by substoichiometric nitrogen ion implantation into silicon is studied as a function of the processing parameters, the implantation dose and temperature, and the presence of capping layers during implantation. Etching characteristics have been probed using tetramethylammonium hydroxide or KOH solutions for different times up to 6 h. Results show that, after annealing, the minimum dose required for the formation of an efficient etch-stop layer is about 4 x 10 17 cm -2 , for an implantation energy of 75 keV. This is defined as a layer with an efficient etch selectivity in relation to Si of s ≥ 100. For larger implantation doses efficient etch selectivities larger than 100 are obtained. However, for these doses a considerable density of pits is observed in the etch-stop layer. These are related to the presence of nitrogen poor Si regions in the buried layer after annealing, due to a partial separation of silicon and silicon nitride phases during the annealing process. The influence of this separation of phases as well as nitrogen gettering in the buried layer on the etch-stop behavior is discussed as a function of the processing parameters

  12. Increased understanding of the biochemistry and biosynthesis of MUC2 and other gel-forming mucins through the recombinant expression of their protein domains.

    Science.gov (United States)

    Bäckström, Malin; Ambort, Daniel; Thomsson, Elisabeth; Johansson, Malin E V; Hansson, Gunnar C

    2013-06-01

    The gel-forming mucins are large and heavily O-glycosylated proteins which build up mucus gels. The recombinant production of full-length gel-forming mucins has not been possible to date. In order to study mucin biosynthesis and biochemistry, we and others have taken the alternative approach of constructing different recombinant proteins consisting of one or several domains of these large proteins and expressing them separately in different cell lines. Using this approach, we have determined that MUC2, the intestinal gel-forming mucin, dimerizes via its C-terminal cysteine-knot domain and also trimerizes via one of the N-terminal von Willebrand D domains. Both of these interactions are disulfide bond mediated. Via this assembly, a molecular network is built by which the mucus gel is formed. Here we discuss not only the functional understanding obtained from studies of the recombinant proteins, but also highlight the difficulties encountered when these proteins were produced recombinantly. We often found an accumulation of the proteins in the ER and consequently no secretion. This was especially apparent when the cysteine-rich domains of the N- and C-terminal parts of the mucins were expressed. Other proteins that we constructed were either not secreted or not expressed at all. Despite these problems, the knowledge of mucin biosynthesis and assembly has advanced considerably through the studies of these recombinant proteins.

  13. Recombinant Forms of Leishmania amazonensis Excreted/Secreted Promastigote Surface Antigen (PSA Induce Protective Immune Responses in Dogs.

    Directory of Open Access Journals (Sweden)

    Elodie Petitdidier

    2016-05-01

    Full Text Available Preventive vaccination is a highly promising strategy for interrupting leishmaniasis transmission that can, additionally, contribute to elimination. A vaccine formulation based on naturally excreted secreted (ES antigens was prepared from L. infantum promastigote culture supernatant. This vaccine achieved successful results in Phase III trials and was licensed and marketed as CaniLeish. We recently showed that newly identified ES promastigote surface antigen (PSA, from both viable promastigotes and axenically-grown amastigotes, represented the major constituent and the highly immunogenic antigen of L. infantum and L. amazonensis ES products. We report here that three immunizations with either the recombinant ES LaPSA-38S (rPSA or its carboxy terminal part LaPSA-12S (Cter-rPSA, combined with QA-21 as adjuvant, confer high levels of protection in naive L. infantum-infected Beagle dogs, as checked by bone marrow parasite absence in respectively 78.8% and 80% of vaccinated dogs at 6 months post-challenge. The parasite burden in infected vaccinated dogs was significantly reduced compared to placebo group, as measured by q-PCR. Moreover, our results reveal humoral and cellular immune response clear-cut differences between vaccinated and control dogs. An early increase in specific IgG2 antibodies was observed in rPSA/QA-21- and Cter-rPSA/QA-21-immunized dogs only. They were found functionally active in vitro and were highly correlated with vaccine protection. In vaccinated protected dogs, IFN-γ and NO productions, as well as anti-leishmanial macrophage activity, were increased. These data strongly suggest that ES PSA or its carboxy-terminal part, in recombinant forms, induce protection in a canine model of zoonotic visceral leishmaniasis by inducing a Th1-dominant immune response and an appropriate specific antibody response. These data suggest that they could be considered as important active components in vaccine candidates.

  14. Molecular epidemiology of HIV-1 among the HIV infected people of Manipur, Northeastern India: Emergence of unique recombinant forms.

    Science.gov (United States)

    Sharma, Adhikarimayum Lakhikumar; Singh, Thiyam Ramsing; Devi, Khuraijam Ranjana; Singh, Lisam Shanjukumar

    2017-06-01

    According to the Joint National Programme on HIV/AIDS (UNAIDS), the northeastern region of India has the highest HIV prevalence in the country. This study was conducted to determine the current HIV-1 molecular epidemiology of Manipur, a state in northeast India. Blood samples from HIV-1 seropositive subjects were collected between June 2011 and February 2014. The partial regions of HIV-1 genes; pol and tat-vpu-env were independently amplified, sequenced, analyzed, and genotyped. Based on all sequences generated from 110 samples using pol and/or tat-vpu-env gene, the overall HIV-1 genotypes distribution of Manipur was as follows: 65.45% (72/110) subtype C, 32.73% (36/110) unique recombinant forms (URFs), and 1.82% (2/110) subtype B. The distribution of HIV-1 genotypes among the risk groups was: heterosexual: 58.33% (35/60) subtype C, 38.33% (23/60) URFs, and 3.34% (2/60) subtype B; intravenous drug users (IDUs): 85.36% (35/41) subtype C, 9.76% (4/41) URFs, and 4.88% (2/41) subtype B; mother to child (MTC): 50% (3/6) URFs and 50% (3/6) subtype C and blood transfusion: 100% (3/3) subtype C. The findings for the first time revealed the emergence of URFs of HIV-1 in Manipur which is predominant among the sexual and MTC risk groups as compared to IDUs. Taking together, this study illustrated that Manipur is the "recombinant hotspot of HIV" of India. The results will provide the clinical importance for continuous monitoring of HIV-infections in order to design appropriate prevention measures to limit the spread of new HIV infections. © 2016 Wiley Periodicals, Inc.

  15. Glycan microarray analysis of the carbohydrate-recognition specificity of native and recombinant forms of the lectin ArtinM

    Directory of Open Access Journals (Sweden)

    Y. Liu

    2015-12-01

    Full Text Available This article contains data related to the researc.h article entitled “Yeast-derived ArtinM shares structure, carbohydrate recognition, and biological effects with native ArtinM” by Cecílio et al. (2015 [1]. ArtinM, a D-mannose-binding lectin isolated from the seeds of Artocarpus heterophyllus, exerts immunomodulatory and regenerative activities through its Carbohydrate Recognition Domain (CRD (Souza et al., 2013; Mariano et al., 2014 [2,3]. The limited availability of the native lectin (n-ArtinM led us to characterize a recombinant form of the protein, obtained by expression in Saccharomyces cerevisiae (y-ArtinM. We compared the carbohydrate-binding specificities of y-ArtinM and n-ArtinM by analyzing the binding of biotinylated preparations of the two lectin forms using a neoglycolipid (NGL-based glycan microarray. Data showed that y-ArtinM mirrored the specificity exhibited by n-ArtinM.

  16. Deuterium trapping in tungsten deposition layers formed by deuterium plasma sputtering

    International Nuclear Information System (INIS)

    Alimov, V.Kh.; Roth, J.; Shu, W.M.; Komarov, D.A.; Isobe, K.; Yamanishi, T.

    2010-01-01

    A study of the influence of the deposition conditions on the surface morphology and deuterium (D) concentration in tungsten (W) deposition layers formed by magnetron sputtering and in the linear plasma generator has been carried out. Thick W layers (≥0.4 μm) deposited onto copper substrates demonstrate areas of pilling and, after post-deposition heating to 1300 K, flaking-off and fracturing. For thin W layers (≤80 nm) deposited onto stainless steel (SS) and W substrates, no areas of flaking-off and fracturing exist both after deposition and after post-deposition heating to 673 K for the SS substrate and to 1300 K for the W substrate. The concentration of deuterium in the W layers was found to decrease with increasing substrate temperature and with increasing tungsten deposition rate. For layers with relatively high concentration of oxygen (0.20-0.60 O/W), a decrease of the D concentration with increasing substrate temperature is more pronounced than that for layers deposited in good vacuum conditions. To describe the evolution of the D/W ratio with the substrate temperature and the tungsten deposition rate, an empirical equation proposed by De Temmerman and Doerner [J. Nucl. Mater. 389 (2009) 479] but with alternative parameters has been used.

  17. Closed-form solution for piezoelectric layer with two collinear cracks parallel to the boundaries

    Directory of Open Access Journals (Sweden)

    B. M. Singh

    2006-01-01

    Full Text Available We consider the problem of determining the stress distribution in an infinitely long piezoelectric layer of finite width, with two collinear cracks of equal length and parallel to the layer boundaries. Within the framework of reigning piezoelectric theory under mode III, the cracked piezoelectric layer subjected to combined electromechanical loading is analyzed. The faces of the layers are subjected to electromechanical loading. The collinear cracks are located at the middle plane of the layer parallel to its face. By the use of Fourier transforms we reduce the problem to solving a set of triple integral equations with cosine kernel and a weight function. The triple integral equations are solved exactly. Closed form analytical expressions for stress intensity factors, electric displacement intensity factors, and shape of crack and energy release rate are derived. As the limiting case, the solution of the problem with one crack in the layer is derived. Some numerical results for the physical quantities are obtained and displayed graphically.

  18. Ordering of Nb3Sn layer formed in the bronze process

    International Nuclear Information System (INIS)

    Agarwal, S.K.; Nagpal, K.C.; Narlikar, A.G.

    1986-01-01

    The work reported here suggests that the ordering of superconducting Nb 3 Sn compound layers formed in the bronze process is much more intriguing than previously assumed. Various possible mechanisms of ordering of the layers have been examined in conjunction with the observed data on short duration annealed samples. The analysis suggests the ordering to be governed by a sequential operation of both Ist and IInd order kinetics, and seems to fall in line with the studies on disordered bulk samples annealed for long durations. (author)

  19. Forming method of a functional layer-built film by micro-wave plasma CVD

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Keishi

    1988-11-18

    In forming an amorphous semi-conductor material film, the micro-wave plasma CVD cannot be generally used because of such demerits as film-separation, low yield, columnar structure in the film, and problems in the optical and electrical properties. In this invention, a specific substrate is placed in a layer-built film forming unit which is capable of maintaining vacuum; raw material gas for the film formation is introduced; plasma is generated by a micro-wave energy to decompose the raw material gas, thus forming the layer-built film on the substarte. Then a film is made by adding a specific amount of calcoganide-containing gas to the raw material gas. By this, the utilization efficiency of the raw material gas gets roughly 100% and both the adhesion to the substrate and the structural flexibility of the layer-built film increase, enhancing the yield of forming various functional elements (sensor, solar cell, thin transistor film, etc.), and thus greatly reducing the production cost. 6 figs., 7 tabs.

  20. Ultra-high resolution X-ray structures of two forms of human recombinant insulin at 100 K.

    Science.gov (United States)

    Lisgarten, David R; Palmer, Rex A; Lobley, Carina M C; Naylor, Claire E; Chowdhry, Babur Z; Al-Kurdi, Zakieh I; Badwan, Adnan A; Howlin, Brendan J; Gibbons, Nicholas C J; Saldanha, José W; Lisgarten, John N; Basak, Ajit K

    2017-08-01

    The crystal structure of a commercially available form of human recombinant (HR) insulin, Insugen (I), used in the treatment of diabetes has been determined to 0.92 Å resolution using low temperature, 100 K, synchrotron X-ray data collected at 16,000 keV (λ = 0.77 Å). Refinement carried out with anisotropic displacement parameters, removal of main-chain stereochemical restraints, inclusion of H atoms in calculated positions, and 220 water molecules, converged to a final value of R = 0.1112 and R free  = 0.1466. The structure includes what is thought to be an ordered propanol molecule (POL) only in chain D(4) and a solvated acetate molecule (ACT) coordinated to the Zn atom only in chain B(2). Possible origins and consequences of the propanol and acetate molecules are discussed. Three types of amino acid representation in the electron density are examined in detail: (i) sharp with very clearly resolved features; (ii) well resolved but clearly divided into two conformations which are well behaved in the refinement, both having high quality geometry; (iii) poor density and difficult or impossible to model. An example of type (ii) is observed for the intra-chain disulphide bridge in chain C(3) between Sγ6-Sγ11 which has two clear conformations with relative refined occupancies of 0.8 and 0.2, respectively. In contrast the corresponding S-S bridge in chain A(1) shows one clearly defined conformation. A molecular dynamics study has provided a rational explanation of this difference between chains A and C. More generally, differences in the electron density features between corresponding residues in chains A and C and chains B and D is a common observation in the Insugen (I) structure and these effects are discussed in detail. The crystal structure, also at 0.92 Å and 100 K, of a second commercially available form of human recombinant insulin, Intergen (II), deposited in the Protein Data Bank as 3W7Y which remains otherwise unpublished is compared here

  1. Ultrathin silicon dioxide layers with a low leakage current density formed by chemical oxidation of Si

    Science.gov (United States)

    Asuha,; Kobayashi, Takuya; Maida, Osamu; Inoue, Morio; Takahashi, Masao; Todokoro, Yoshihiro; Kobayashi, Hikaru

    2002-10-01

    Chemical oxidation of Si by use of azeotrope of nitric acid and water can form 1.4-nm-thick silicon dioxide layers with a leakage current density as low as those of thermally grown SiO2 layers. The capacitance-voltage (C-V) curves for these ultrathin chemical SiO2 layers have been measured due to the low leakage current density. The leakage current density is further decreased to approx1/5 (cf. 0.4 A/cm2 at the forward gate bias of 1 V) by post-metallization annealing at 200 degC in hydrogen. Photoelectron spectroscopy and C-V measurements show that this decrease results from (i) increase in the energy discontinuity at the Si/SiO2 interface, and (ii) elimination of Si/SiO2 interface states and SiO2 gap states.

  2. Hydrogen and helium trapping in tungsten deposition layers formed by RF plasma sputtering

    International Nuclear Information System (INIS)

    Kazunari Katayama; Kazumi Imaoka; Takayuki Okamura; Masabumi Nishikawa

    2006-01-01

    Understanding of tritium behavior in plasma facing materials is an important issue for fusion reactor from viewpoints of fuel control and radiation safety. Tungsten is used as a plasma facing material in the divertor region of ITER. However, investigation of hydrogen isotope behavior in tungsten deposition layer is not sufficient so far. It is also necessary to evaluate an effect of helium on a formation of deposition layer and an accumulation of hydrogen isotopes because helium generated by fusion reaction exists in fusion plasma. In this study, tungsten deposition layers were formed by sputtering method using hydrogen and helium RF plasma. An erosion rate and a deposition rate of tungsten were estimated by weight measurement. Hydrogen and helium retention were investigated by thermal desorption method. Tungsten deposition was performed using a capacitively-coupled RF plasma device equipped with parallel-plate electrodes. A tungsten target was mounted on one electrode which is supplied with RF power at 200 W. Tungsten substrates were mounted on the other electrode which is at ground potential. The plasma discharge was continued for 120 hours where pressure of hydrogen or helium was controlled to be 10 Pa. The amounts of hydrogen and helium released from deposition layers was quantified by a gas chromatograph. The erosion rate of target tungsten under helium plasma was estimated to be 1.8 times larger than that under hydrogen plasma. The deposition rate on tungsten substrate under helium plasma was estimated to be 4.1 times larger than that under hydrogen plasma. Atomic ratio of hydrogen to tungsten in a deposition layer formed by hydrogen plasma was estimated to be 0.17 by heating to 600 o C. From a deposition layer formed by helium plasma, not only helium but also hydrogen was released by heating to 500 o C. Atomic ratios of helium and hydrogen to tungsten were estimated to be 0.080 and 0.075, respectively. The trapped hydrogen is probably impurity hydrogen

  3. Production of Mucosally Transmissible SHIV Challenge Stocks from HIV-1 Circulating Recombinant Form 01_AE env Sequences.

    Directory of Open Access Journals (Sweden)

    Lawrence J Tartaglia

    2016-02-01

    Full Text Available Simian-human immunodeficiency virus (SHIV challenge stocks are critical for preclinical testing of vaccines, antibodies, and other interventions aimed to prevent HIV-1. A major unmet need for the field has been the lack of a SHIV challenge stock expressing circulating recombinant form 01_AE (CRF01_AE env sequences. We therefore sought to develop mucosally transmissible SHIV challenge stocks containing HIV-1 CRF01_AE env derived from acutely HIV-1 infected individuals from Thailand. SHIV-AE6, SHIV-AE6RM, and SHIV-AE16 contained env sequences that were >99% identical to the original HIV-1 isolate and did not require in vivo passaging. These viruses exhibited CCR5 tropism and displayed a tier 2 neutralization phenotype. These challenge stocks efficiently infected rhesus monkeys by the intrarectal route, replicated to high levels during acute infection, and established chronic viremia in a subset of animals. SHIV-AE16 was titrated for use in single, high dose as well as repetitive, low dose intrarectal challenge studies. These SHIV challenge stocks should facilitate the preclinical evaluation of vaccines, monoclonal antibodies, and other interventions targeted at preventing HIV-1 CRF01_AE infection.

  4. Method of forming a plasma sprayed interconnection layer on an electrode of an electrochemical cell

    Science.gov (United States)

    Spengler, Charles J.; Folser, George R.; Vora, Shailesh D.; Kuo, Lewis; Richards, Von L.

    1995-01-01

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by plasma spraying doped LaCrO.sub.3 powder, preferably compensated with chromium as Cr.sub.2 O.sub.3 and/or dopant element, preferably by plasma arc spraying; and, (C) heating the doped and compensated LaCrO.sub.3 layer to about 1100.degree. C. to 1300.degree. C. to provide a dense, substantially gas-tight, substantially hydration-free, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the unselected portion of the air electrode, and a fuel electrode can be applied to the solid electrolyte, to provide an electrochemical cell.

  5. Study on the CMP characteristics of a copper passivity layer formed by dipping in an oxidizer

    International Nuclear Information System (INIS)

    Choi, Youn-Ok; Lee, Woo-Sun; Choi, Gwon-Woo; Lee, Kang-Yeon; Kim, Nam-Oh

    2011-01-01

    Copper has been the material for ultra-large-scale integrated circuits owing to its excellent electromigration resistance and low electrical resistance. The polishing mechanism of metal chemical mechanical polishing (CMP) has been reported to be a repeated process of passive oxide layer formation through the use of on oxidizer and then the abrasion action of the slurry. However, because copper is softer and more sensitive to corrosion than tungsten, the slurry composition and the polishing mechanism during the copper CMP process may be more complicated. In a general Cu-CMP process, a mixture of an alumina-based slurry and an oxidizer in proper proportion is used in order to form a passive oxide layer such as CuO and CuO 2 . However, a conventional CMP process consumes an unnecessary amount of slurry to formed the passive layer. Therefore, in this paper, we propose a new method. The copper samples were oxidized by dipping in an oxidizer for an appropriate time to minimize the consumption of slurry before the CMP process. Then, we performed the CMP process. In order to compare the polishing characteristics of the copper thin film, we discuss the CMP removal rate and non-uniformity, as well as the microstructure of the surface and a layer cross-section based on a scanning.

  6. Study on the use of TiO{sub 2} passivation layer to reduce recombination losses in dye sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Eskander bin Samsudin, Adel; Mohamed, Norani Muti; Nayan, Nafarizal; Ali, Riyaz Ahmad Mohamed; Shariffuddin, Sharifah Amira Amir; Omar, Salwa [Electrical and Electronics Department, 31750, Tronoh, Universiti Teknologi PETRONAS (Malaysia); Fundamental and Applied Sciences Department, 31750, Tronoh, Universiti Teknologi PETRONAS (Malaysia); Electronic Engineering Department, Electrical and Electronic Engineering Faculty, Universiti Tun Hussein Onn Malaysia (UTHM) (Malaysia)

    2012-09-26

    A lot of research on various aspects of dye solar cells (DSC) has been carried out in order to improve efficiency. This paper analyzes the utilization of TiO{sub 2} passivation layers of different thicknesses by improving the electron transport properties. Four different thicknesses of passivation layers namely 10, 20, 50 and 100 nm were deposited onto the working electrode using r.f sputtering. The electrodes were assembled into TiO{sub 2} based DSC with active area of 1 cm{sup 2}. The solar performance was investigated using 100 mW/cm{sup 2} of AM 1.5 simulated sunlight from solar simulator. The kinetics of the solar cells was investigated using Electrochemical Impedance Spectroscopy (EIS) measurement and the spectral response was measured using Incident Photon to Electron Conversion (IPCE) measurement system. The highest efficiency was found for DSC with 20 nm passivation layer. DSCs with the passivation layer have open circuit voltage, V{sub OC} increased by 57 mV, their current density, J{sub SC} increased by 0.774 mA cm{sup -2} compared to the one without the passivation layer. The quantum efficiency of the 20 nm passivation layer is the highest, peaking at the wavelength of 534 nm, resulting in the highest performance. All DSCs with the passivation layer recorded higher ratio of R{sub BR}/R{sub T} where R{sub T} is the diffusion resistance of the TiO{sub 2} particles in the mesoscopic layer and R{sub BR} is the recombination resistance of the electron to the electrolyte. This implies that the recombination of the electrolyte I{sup -}{sub 3}/3I{sup -} couple at the substrate/electrolyte interface has been effectively reduced resulting in an enhanced efficiency.

  7. Methods of generalizing and classifying layer structures of a special form

    Energy Technology Data Exchange (ETDEWEB)

    Viktorova, N P

    1981-09-01

    An examination is made of the problem of classifying structures represented by weighted multilayer graphs of special form with connections between the vertices of each layer. The classification of structures of such a form is based on the construction of resolving sets of graphs as a result of generalization of the elements of the training sample of each class and the testing of whether an input object is isomorphic (with allowance for the weights) to the structures of the resolving set or not. 4 references.

  8. Optical and electrical properties of porous silicon layer formed on the textured surface by electrochemical etching

    Science.gov (United States)

    Weiying, Ou; Lei, Zhao; Hongwei, Diao; Jun, Zhang; Wenjing, Wang

    2011-05-01

    Porous silicon (PS) layers were formed on textured crystalline silicon by electrochemical etching in HF-based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studied. Moreover, the influences of the initial structures and the anodizing time on the optical and electrical properties of the surfaces after PS formation are investigated. The results show that the TMAH textured surfaces with PS formation present a dramatic decrease in reflectance. The longer the anodizing time is, the lower the reflectance. Moreover, an initial surface with bigger pyramids achieved lower reflectance in a short wavelength range. A minimum reflectance of 3.86% at 460 nm is achieved for a short anodizing time of 2 min. Furthermore, the reflectance spectrum of the sample, which was etched in 3 vol.% TMAH for 25 min and then anodized for 20 min, is extremely flat and lies between 3.67% and 6.15% in the wavelength range from 400 to 1040 nm. In addition, for a short anodizing time, a slight increase in the effective carrier lifetime is observed. Our results indicate that PS layers formed on a TMAH textured surface for a short anodization treatment can be used as both broadband antireflection coatings and passivation layers for the application in solar cells.

  9. Optical and electrical properties of porous silicon layer formed on the textured surface by electrochemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Ou Weiying; Zhao Lei; Diao Hongwei; Zhang Jun; Wang Wenjing, E-mail: wjwangwj@126.com [Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-05-15

    Porous silicon (PS) layers were formed on textured crystalline silicon by electrochemical etching in HF-based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studied. Moreover, the influences of the initial structures and the anodizing time on the optical and electrical properties of the surfaces after PS formation are investigated. The results show that the TMAH textured surfaces with PS formation present a dramatic decrease in reflectance. The longer the anodizing time is, the lower the reflectance. Moreover, an initial surface with bigger pyramids achieved lower reflectance in a short wavelength range. A minimum reflectance of 3.86% at 460 nm is achieved for a short anodizing time of 2 min. Furthermore, the reflectance spectrum of the sample, which was etched in 3 vol.% TMAH for 25 min and then anodized for 20 min, is extremely flat and lies between 3.67% and 6.15% in the wavelength range from 400 to 1040 nm. In addition, for a short anodizing time, a slight increase in the effective carrier lifetime is observed. Our results indicate that PS layers formed on a TMAH textured surface for a short anodization treatment can be used as both broadband antireflection coatings and passivation layers for the application in solar cells. (semiconductor technology)

  10. Study of shifting of recombination zone in multi-emissive layer organic light emitting devices and its effect on color stability

    International Nuclear Information System (INIS)

    Tyagi, Priyanka; Srivastava, Ritu; Kumar, Arunandan; Tuli, Suneet; Kamalasanan, M.N.

    2013-01-01

    Color stability in multi-emissive layer organic light emitting devices (Me-OLEDs) has been investigated. Me-OLEDs were based on multiple emitters with a common host CBP doped with three dopants, BCzVBi, Ir(ppy) 3 and Ir(btp) 2 acac for blue, green and red emission. A major variation in CIE coordinates were found from (0.312, 0.294) to (0.236, 0.267) with increase in voltage from 6 to 9 V. This coordinate shift in Me-OLEDs has been attributed to the shifting of recombination zone with increase in voltage. In order to support our experimental observation, the EL spectrum of Me-OLEDs has been expressed as a linear combination of EL intensities of OLEDs with its individual constituting layers as emitters. In this way, the contribution of each layer in the EL spectrum of Me-OLEDs has been evaluated at each voltage. It has been observed from these calculations that the contribution of red emitter decreases from 47% to 33.33% and blue emitter increases from 38% to 51.67% with the increase in voltage from 6 to 9 V. This supports our hypothesis of shifting of recombination zone with the change in voltage. This shifting has been attributed to the field dependency of electron mobility in CBP. Me-OLED with CBP layers between the emitters was fabricated to improve the color stability. Significant improvement in color stability was achieved without changes in current efficiency in Me-OLED with interlayers. Highlights: ► Me-OLEDs have been fabricated by using three primary colors (RGB). ► CIE coordinates of these Me-OLEDs were voltage dependent. ► Analytical fitting has been performed to study the shifting of recombination zone. ► CBP interlayers have been introduced to improve the color stability. ► Color stability has been improved without any change in current efficiency

  11. Method of generating magnetoactive plasma for forming thin surface layers on solid substrates and equipment therefor

    International Nuclear Information System (INIS)

    Bardos, L.; Loncar, G.; Musil, J.; Zacek, F.

    1979-01-01

    The invention essentially consists in the use of the axially symmetrical high-frequency magnetized plasma column for thin layer formation. The plasma is generated using a cylindrical microwave slow-down structure in the outer magnetic field. Plasma particles density and temperature and their radial distribution are adjusted by changing the intensity of the magnetic field and of high-frequency power. The plasma may be generated from any gases in a pressure range of 10 -3 to 10 2 Pa. In an oxygen plasma, e.g., it is thus possible to form layers of 200 nm in thickness in 60 mins at an input high-frequency power of 100 to 300 W. (J.U.)

  12. A X-ray diffraction analysis on constituent distribution of heavy rust layer formed on weathering steel using synchrotron radiation

    International Nuclear Information System (INIS)

    Hara, Shuichi

    2008-01-01

    A local structural analysis of heavy rust layers with large swelling and laminated layers formed on weathering steel bridges using synchrotron radiation X-ray diffraction (SR-XRD) in SPring-8 have been performed. The main constituent in average composition of the whole layer was spinel-type iron oxide [mainly Magnetite (Fe 3 O 4 )] and the mass ratio was 30-40 mass%. In contrast the mass ratio of spinel in its local parts, i.e., outer layer, inter-layer and inner layer position was not higher in common but the mass ratio of β-FeOOH was higher. Therefore it indicates that these heavy rust layers have been composed of many layers of spinel poor, rich and poor - cell (SPRaP-cell). Thus SR-XRD is useful for the analysis of the constituent distribution in the rust layer. (author)

  13. Molecular Diversity of HIV-1 among People Who Inject Drugs in Kuala Lumpur, Malaysia: Massive Expansion of Circulating Recombinant Form (CRF) 33_01B and Emergence of Multiple Unique Recombinant Clusters

    Science.gov (United States)

    Chow, Wei Zhen; Ng, Kim Tien; Yong, Yean Kong; Azmel, Azureen; Takebe, Yutaka; Al-Darraji, Haider Abdulrazzaq Abed; Kamarulzaman, Adeeba; Tee, Kok Keng

    2013-01-01

    Since the discovery of HIV-1 circulating recombinant form (CRF) 33_01B in Malaysia in the early 2000 s, continuous genetic diversification and active recombination involving CRF33_01B and other circulating genotypes in the region including CRF01_AE and subtype B′ of Thai origin, have led to the emergence of novel CRFs and unique recombinant forms. The history and magnitude of CRF33_01B transmission among various risk groups including people who inject drugs (PWID) however have not been investigated despite the high epidemiological impact of CRF33_01B in the region. We update the most recent molecular epidemiology of HIV-1 among PWIDs recruited in Malaysia between 2010 and 2011 by population sequencing and phylogenetic analysis of 128 gag-pol sequences. HIV-1 CRF33_01B was circulating among 71% of PWIDs whilst a lower prevalence of other previously dominant HIV-1 genotypes [subtype B′ (11%) and CRF01_AE (5%)] and CRF01_AE/B′ unique recombinants (13%) were detected, indicating a significant shift in genotype replacement in this population. Three clusters of CRF01_AE/B′ recombinants displaying divergent yet phylogenetically-related mosaic genomes to CRF33_01B were identified and characterized, suggestive of an abrupt emergence of multiple novel CRF clades. Using rigorous maximum likelihood approach and the Bayesian Markov chain Monte Carlo (MCMC) sampling of CRF33_01Bpol sequences to elucidate the past population dynamics, we found that the founder lineages of CRF33_01B were likely to have first emerged among PWIDs in the early 1990 s before spreading exponentially to various high and low-risk populations (including children who acquired infections from their mothers) and later on became endemic around the early 2000 s. Taken together, our findings provide notable genetic evidence indicating the widespread expansion of CRF33_01B among PWIDs and into the general population. The emergence of numerous previously unknown recombinant clades highlights the

  14. Molecular diversity of HIV-1 among people who inject drugs in Kuala Lumpur, Malaysia: massive expansion of circulating recombinant form (CRF) 33_01B and emergence of multiple unique recombinant clusters.

    Science.gov (United States)

    Chow, Wei Zhen; Ong, Lai Yee; Razak, Siti Humaira; Lee, Yeat Mei; Ng, Kim Tien; Yong, Yean Kong; Azmel, Azureen; Takebe, Yutaka; Al-Darraji, Haider Abdulrazzaq Abed; Kamarulzaman, Adeeba; Tee, Kok Keng

    2013-01-01

    Since the discovery of HIV-1 circulating recombinant form (CRF) 33_01B in Malaysia in the early 2000 s, continuous genetic diversification and active recombination involving CRF33_01B and other circulating genotypes in the region including CRF01_AE and subtype B' of Thai origin, have led to the emergence of novel CRFs and unique recombinant forms. The history and magnitude of CRF33_01B transmission among various risk groups including people who inject drugs (PWID) however have not been investigated despite the high epidemiological impact of CRF33_01B in the region. We update the most recent molecular epidemiology of HIV-1 among PWIDs recruited in Malaysia between 2010 and 2011 by population sequencing and phylogenetic analysis of 128 gag-pol sequences. HIV-1 CRF33_01B was circulating among 71% of PWIDs whilst a lower prevalence of other previously dominant HIV-1 genotypes [subtype B' (11%) and CRF01_AE (5%)] and CRF01_AE/B' unique recombinants (13%) were detected, indicating a significant shift in genotype replacement in this population. Three clusters of CRF01_AE/B' recombinants displaying divergent yet phylogenetically-related mosaic genomes to CRF33_01B were identified and characterized, suggestive of an abrupt emergence of multiple novel CRF clades. Using rigorous maximum likelihood approach and the Bayesian Markov chain Monte Carlo (MCMC) sampling of CRF33_01Bpol sequences to elucidate the past population dynamics, we found that the founder lineages of CRF33_01B were likely to have first emerged among PWIDs in the early 1990 s before spreading exponentially to various high and low-risk populations (including children who acquired infections from their mothers) and later on became endemic around the early 2000 s. Taken together, our findings provide notable genetic evidence indicating the widespread expansion of CRF33_01B among PWIDs and into the general population. The emergence of numerous previously unknown recombinant clades highlights the escalating

  15. Molecular diversity of HIV-1 among people who inject drugs in Kuala Lumpur, Malaysia: massive expansion of circulating recombinant form (CRF 33_01B and emergence of multiple unique recombinant clusters.

    Directory of Open Access Journals (Sweden)

    Wei Zhen Chow

    Full Text Available Since the discovery of HIV-1 circulating recombinant form (CRF 33_01B in Malaysia in the early 2000 s, continuous genetic diversification and active recombination involving CRF33_01B and other circulating genotypes in the region including CRF01_AE and subtype B' of Thai origin, have led to the emergence of novel CRFs and unique recombinant forms. The history and magnitude of CRF33_01B transmission among various risk groups including people who inject drugs (PWID however have not been investigated despite the high epidemiological impact of CRF33_01B in the region. We update the most recent molecular epidemiology of HIV-1 among PWIDs recruited in Malaysia between 2010 and 2011 by population sequencing and phylogenetic analysis of 128 gag-pol sequences. HIV-1 CRF33_01B was circulating among 71% of PWIDs whilst a lower prevalence of other previously dominant HIV-1 genotypes [subtype B' (11% and CRF01_AE (5%] and CRF01_AE/B' unique recombinants (13% were detected, indicating a significant shift in genotype replacement in this population. Three clusters of CRF01_AE/B' recombinants displaying divergent yet phylogenetically-related mosaic genomes to CRF33_01B were identified and characterized, suggestive of an abrupt emergence of multiple novel CRF clades. Using rigorous maximum likelihood approach and the Bayesian Markov chain Monte Carlo (MCMC sampling of CRF33_01Bpol sequences to elucidate the past population dynamics, we found that the founder lineages of CRF33_01B were likely to have first emerged among PWIDs in the early 1990 s before spreading exponentially to various high and low-risk populations (including children who acquired infections from their mothers and later on became endemic around the early 2000 s. Taken together, our findings provide notable genetic evidence indicating the widespread expansion of CRF33_01B among PWIDs and into the general population. The emergence of numerous previously unknown recombinant clades highlights the

  16. Enhanced direct-gap light emission from Si-capped n+-Ge epitaxial layers on Si after post-growth rapid cyclic annealing: impact of non-radiative interface recombination toward Ge/Si double heterostructure lasers.

    Science.gov (United States)

    Higashitarumizu, Naoki; Ishikawa, Yasuhiko

    2017-09-04

    Enhanced direct-gap light emission is reported for Si-capped n + -Ge layers on Si after post-growth rapid cyclic annealing (RCA), and impact of non-radiative recombination (NRR) at the Ge/Si interface is discussed toward Ge/Si double heterostructure (DH) lasers. P-doped n + -Ge layer (1 × 10 19 cm -3 , 400 nm) is grown on Si by ultra-high vacuum chemical vapor deposition, followed by a growth of Si capping layer (5 nm) to form a Si/Ge/Si DH structure. Post-growth RCA to eliminate defects in Ge is performed in N 2 at temperatures between 900°C and 780°C, where the annealing time is minimized to be 5 s in each RCA cycle to prevent an out-diffusion of P dopants from the Ge surface. Direct-gap photoluminescence (PL) intensity at 1.6 µm increases with the RCA cycles up to 40, although the threading dislocation density in Ge is not reduced after 3 cycles in the present condition. The PL enhancement is ascribed to the suppression of NRR at the Ge/Si interface, where an intermixed SiGe alloy is formed. For Ge/Si DH lasers, NRR at the Ge/Si interface is found to have a significant impact on the threshold current density Jth. In order to achieve Jth on the order of 1 kA/cm 2 , similar to III-V lasers, the interface recombination velocity S is required below 10 3 cm/s in spite of S as large as 10 5 cm/s at the ordinary defect-rich Ge/Si interface.

  17. Effect of Al 2 O 3 Recombination Barrier Layers Deposited by Atomic Layer Deposition in Solid-State CdS Quantum Dot-Sensitized Solar Cells

    KAUST Repository

    Roelofs, Katherine E.; Brennan, Thomas P.; Dominguez, Juan C.; Bailie, Colin D.; Margulis, George Y.; Hoke, Eric T.; McGehee, Michael D.; Bent, Stacey F.

    2013-01-01

    Despite the promise of quantum dots (QDs) as a light-absorbing material to replace the dye in dye-sensitized solar cells, quantum dot-sensitized solar cell (QDSSC) efficiencies remain low, due in part to high rates of recombination. In this article

  18. Increased levels of IgA antibodies against CRA and FRA recombinant antigens of Trypanosoma cruzi differentiate digestive forms of Chagas disease.

    Science.gov (United States)

    Vasconcelos, Romero H T; Amaral, Fábio N; Cavalcanti, Maria G A M; Silva, Edimilson D; Ferreira, Antonio G P; Morais, Clarice N L; Gomes, Yara M

    2010-10-01

    In the chronic phase of Chagas disease, individuals infected by Trypanosoma cruzi may be asymptomatic or may present cardiac and/or digestive complications. Our aim here was to analyze the relationship between the presence of specific immunoglobulin A antibodies and the different chronic clinical forms of Chagas disease using two recombinant antigens of Trypanosoma cruzi, cytoplasmatic repetitive antigen and flagellar repetitive antigen. The association of this immunoglobulin isotype with the digestive and cardio-digestive forms of the disease determined by indirect enzyme-linked immunosorbent assay, strongly suggests that IgA antibodies against these recombinant antigens of T. cruzi can be used as an immunological marker of the digestive alterations caused by Chagas disease. The tests performed in this study show that it is possible to differentiate digestive forms of Chagas disease. The knowledge provided by these results may help physicians to manage early alterations in the digestive tract of patients with the indeterminate or cardiac forms of Chagas disease. Prospective studies, however, with follow-up of the patients that presenting with high levels of immunoglobulin A against cytoplasmatic repetitive antigen and flagellar repetitive antigen recombinant antigens, need to be conducted to confirm this hypothesis. 2010 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

  19. Ionic double layer of atomically flat gold formed on mica templates

    International Nuclear Information System (INIS)

    Chilcott, Terry C.; Wong, Elicia L.S.; Coster, Hans G.L.; Coster, Adelle C.F.; James, Michael

    2009-01-01

    Electrical impedance spectroscopy characterisations of gold surfaces formed on mica templates in contact with potassium chloride electrolytes were performed at the electric potential of zero charge over a frequency range of 6 x 10 -3 to 100 x 10 3 Hz. They revealed constant-phase-angle (CPA) behaviour with a frequency exponent value of 0.96 for surfaces that were also characterised as atomically flat using atomic force microscopy (AFM). As the frequency exponent value was only marginally less than unity, the CPA behaviour yielded a realistic estimate for the capacitance of the ionic double layer. The retention of the CPA behaviour was attributed to specific adsorption of chloride ions which was detected as an adsorption conductance element in parallel with the CPA impedance element. Significant variations in the ionic double layer capacitance as well as the adsorption conductance were observed for electrolyte concentrations ranging from 33 μM to 100 mM, but neither of these variations correlated with concentration. This is consistent with the electrical properties of the interface deriving principally from the inner or Stern region of the double layer.

  20. TiO 2 Conduction Band Modulation with In 2 O 3 Recombination Barrier Layers in Solid-State Dye-Sensitized Solar Cells

    KAUST Repository

    Brennan, Thomas P.

    2013-11-21

    Atomic layer deposition (ALD) was used to grow subnanometer indium oxide recombination barriers in a solid-state dye-sensitized solar cell (DSSC) based on the spiro-OMeTAD hole-transport material (HTM) and the WN1 donor-π-acceptor organic dye. While optimal device performance was achieved after 3-10 ALD cycles, 15 ALD cycles (∼2 Å of In2O 3) was observed to be optimal for increasing open-circuit voltage (VOC) with an average improvement of over 100 mV, including one device with an extremely high VOC of 1.00 V. An unexpected phenomenon was observed after 15 ALD cycles: the increasing VOC trend reversed, and after 30 ALD cycles VOC dropped by over 100 mV relative to control devices without any In2O3. To explore possible causes of the nonmonotonic behavior resulting from In2O3 barrier layers, we conducted several device measurements, including transient photovoltage experiments and capacitance measurements, as well as density functional theory (DFT) studies. Our results suggest that the VOC gains observed in the first 20 ALD cycles are due to both a surface dipole that pulls up the TiO2 conduction band and recombination suppression. After 30 ALD cycles, however, both effects are reversed: the surface dipole of the In2O3 layer reverses direction, lowering the TiO 2 conduction band, and mid-bandgap states introduced by In 2O3 accelerate recombination, leading to a reduced V OC. © 2013 American Chemical Society.

  1. Electrodeposited Organic Layers Formed from Aryl Diazonium Salts for Inhibition of Copper Corrosion

    Directory of Open Access Journals (Sweden)

    Ana Chira

    2017-02-01

    Full Text Available Copper substrates deposed on a gold screen-printed electrode were covered with different aryl diazonium salts by electrodeposition at 0.25 mA for 30 or 300 s. Seven compounds were investigated: 4-aminophenylacetic acid, 4-aminophenethyl alcohol, 4-fluoroaniline, 4-(heptadecafluorooctylaniline, 4-aminoantipyrine, 4-(4-aminophenylbutyric acid and 3,4,5-trimethoxyaniline. Quantitative monitoring of the electrodeposition process was carried out by electrogravimetry using quartz crystal microbalance (QCM. The electrodeposited mass varies between 26 ng/cm2 for 4-fluoroaniline formed during 30 s to 442 ng/cm2 for 4-phenylbutyric acid formed during 300 s. The corrosion inhibition properties of aryl-modified layers have been studied in buffer citrate with pH = 3 or 3.5% NaCl solutions using electrochemical noise (ECN and Tafel potentiodynamic polarization measurements. A corrosion inhibiting efficiency up to 90% was found. The highest corrosion inhibition was obtained for 4-(4-aminophenylbutyric acid and the lowest for 4-fluoroaniline. A relation between the inhibition efficiency and the chemical nature of the substituents in the protective layer was found.

  2. Electrodeposited Organic Layers Formed from Aryl Diazonium Salts for Inhibition of Copper Corrosion.

    Science.gov (United States)

    Chira, Ana; Bucur, Bogdan; Radu, Gabriel-Lucian

    2017-02-28

    Copper substrates deposed on a gold screen-printed electrode were covered with different aryl diazonium salts by electrodeposition at 0.25 mA for 30 or 300 s. Seven compounds were investigated: 4-aminophenylacetic acid, 4-aminophenethyl alcohol, 4-fluoroaniline, 4-(heptadecafluorooctyl)aniline, 4-aminoantipyrine, 4-(4-aminophenyl)butyric acid and 3,4,5-trimethoxyaniline. Quantitative monitoring of the electrodeposition process was carried out by electrogravimetry using quartz crystal microbalance (QCM). The electrodeposited mass varies between 26 ng/cm² for 4-fluoroaniline formed during 30 s to 442 ng/cm² for 4-phenylbutyric acid formed during 300 s. The corrosion inhibition properties of aryl-modified layers have been studied in buffer citrate with pH = 3 or 3.5% NaCl solutions using electrochemical noise (ECN) and Tafel potentiodynamic polarization measurements. A corrosion inhibiting efficiency up to 90% was found. The highest corrosion inhibition was obtained for 4-(4-aminophenyl)butyric acid and the lowest for 4-fluoroaniline. A relation between the inhibition efficiency and the chemical nature of the substituents in the protective layer was found.

  3. Recombination Suppression in PbS Quantum Dot Heterojunction Solar Cells by Energy-Level Alignment in the Quantum Dot Active Layers.

    Science.gov (United States)

    Ding, Chao; Zhang, Yaohong; Liu, Feng; Nakazawa, Naoki; Huang, Qingxun; Hayase, Shuzi; Ogomi, Yuhei; Toyoda, Taro; Wang, Ruixiang; Shen, Qing

    2017-09-22

    Using spatial energy-level gradient engineering with quantum dots (QDs) of different sizes to increase the generated carrier collection at the junction of a QD heterojunction solar cell (QDHSC) is a hopeful route for improving the energy-conversion efficiency. However, the results of current related research have shown that a variable band-gap structure in a QDHSC will create an appreciable increase, not in the illumination current density, but rather in the fill factor. In addition, there are a lack of studies on the mechanism of the effect of these graded structures on the photovoltaic performance of QDHSCs. This study presents the development of air atmosphere solution-processed TiO 2 /PbS QDs/Au QDHSCs by engineering the energy-level alignment (ELA) of the active layer via the use of a sorted order of differently sized QD layers (four QD sizes). In comparison to the ungraded device (without the ELA), the optimized graded architecture (containing the ELA) solar cells exhibited a great increase (21.4%) in short-circuit current density (J sc ). As a result, a J sc value greater than 30 mA/cm 2 has been realized in planar, thinner absorption layer (∼300 nm) PbS QDHSCs, and the open-circuit voltage (V oc ) and power-conversion efficiency (PCE) were also improved. Through characterization by the light intensity dependences of the J sc and V oc and transient photovoltage decay, we find that (i) the ELA structure, serving as an electron-blocking layer, reduces the interfacial recombination at the PbS/anode interface, and (ii) the ELA structure can drive more carriers toward the desirable collection electrode, and the additional carriers can fill the trap states, reducing the trap-assisted recombination in the PbS QDHSCs. This work has clearly elucidated the mechanism of the recombination suppression in the graded QDHSCs and demonstrated the effects of ELA structure on the improvement of J sc . The charge recombination mechanisms characterized in this work would be

  4. Conversion of recombinant hirudin to the natural form by in vitro tyrosine sulfation. Differential substrate specificities of leech and bovine tyrosylprotein sulfotransferases.

    Science.gov (United States)

    Niehrs, C; Huttner, W B; Carvallo, D; Degryse, E

    1990-06-05

    Hirudin, a tyrosine-sulfated protein secreted by the leech Hirudo medicinalis, is one of the most potent anticoagulants known. The hirudin cDNA has previously been cloned and has been expressed in yeast, but the resulting recombinant protein was found to be produced in the unsulfated form, which is known to have an at least 10 times lower affinity for thrombin than the naturally occurring tyrosine-sulfated hirudin. Here we describe the in vitro tyrosine sulfation of recombinant hirudin by leech and bovine tyrosylprotein sulfotransferase (TPST). With both enzymes, in vitro sulfation of recombinant hirudin occurred at the physiological site (Tyr-63) and rendered the protein biochemically and biologically indistinguishable from natural hirudin. However, leech TPST had an over 20-fold lower apparent Km value for recombinant hirudin than bovine TPST. Further differences in the catalytic properties of leech and bovine TPSTs were observed when synthetic peptides were tested as substrates. Moreover, a synthetic peptide corresponding to the 9 carboxyl-terminal residues of hirudin (which include Tyr-63) was sulfated by leech TPST with a similar apparent Km value as full length hirudin, indicating that structural determinants residing in the immediate vicinity of Tyr-63 are sufficient for sulfation to occur.

  5. Pronounced Photovoltaic Response from Multi-layered MoTe2 Phototransistor with Asymmetric Contact Form.

    Science.gov (United States)

    Liu, Junku; Guo, Nan; Xiao, Xiaoyang; Zhang, Kenan; Jia, Yi; Zhou, Shuyun; Wu, Yang; Li, Qunqing; Xiao, Lin

    2017-11-22

    In this study, we fabricate air-stable p-type multi-layered MoTe 2 phototransistor using Au as electrodes, which shows pronounced photovoltaic response in off-state with asymmetric contact form. By analyzing the spatially resolved photoresponse using scanning photocurrent microscopy, we found that the potential steps are formed in the vicinity of the electrodes/MoTe 2 interface due to the doping of the MoTe 2 by the metal contacts. The potential step dominates the separation of photoexcited electron-hole pairs in short-circuit condition or with small V sd biased. Based on these findings, we infer that the asymmetric contact cross-section between MoTe 2 -source and MoTe 2 -drain electrodes is the reason to form non-zero net current and photovoltaic response. Furthermore, MoTe 2 phototransistor shows a faster response in short-circuit condition than that with higher biased V sd within sub-millisecond, and its spectral range can be extended to the infrared end of 1550 nm.

  6. Effect of irradiation on the evolution of alteration layer formed during nuclear glass leaching

    International Nuclear Information System (INIS)

    Mougnaud, Sarah

    2016-01-01

    High-level radioactive waste (HLW) remaining after spent nuclear fuel reprocessing is immobilized within a glass matrix, eventually destined for geological disposal. Water intrusion into the repository is expected after several thousand years. The alteration of a non-radioactive surrogate for nuclear glass has been extensively studied and it has been determined that successive leaching mechanisms lead to the formation of a 'passivating' alteration layer and to the establishment of a residual rate regime in the long term. However, glass packages are submitted to the radioactivity of confined radioelements. This work focuses on the influence of irradiation on the alteration layer formed during the residual rate regime, in a structural and mechanistic point of view. Three focal areas have been selected. Non-radioactive simple glasses have been leached and externally irradiated in order to determine modifications induced by electronic effects (irradiations with electrons and alpha particles). The same type of glass samples have been previously irradiated with heavy ions and their leaching behavior have been studied in order to assess the impact of ballistic dose cumulated by the glass before water intrusion. Leaching behavior of a complex radioactive glass, doped with an alpha-emitter, has been studied to consider a more realistic situation. (author) [fr

  7. Identification of a recombinant inulin fructotransferase (difructose dianhydride III forming) from Arthrobacter sp. 161MFSha2.1 with high specific activity and remarkable thermostability.

    Science.gov (United States)

    Wang, Xiao; Yu, Shuhuai; Zhang, Tao; Jiang, Bo; Mu, Wanmeng

    2015-04-08

    Difructose dianhydride III (DFA III) is a functional carbohydrate produced from inulin by inulin fructotransferase (IFTase, EC 4.2.2.18). In this work, an IFTase gene from Arthrobacter sp. 161MFSha2.1 was cloned and expressed in Escherachia coli. The recombinant enzyme was purified by metal affinity chromatography. It showed significant inulin hydrolysis activity, and the produced main product from inulin was determined as DFA III by nuclear magnetic resonance analysis. The molecular mass of the purified protein was calculated to be 43 and 125 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, respectively, suggesting the native enzyme might be a homotrimer. The recombinant enzyme showed maximal activity as 2391 units/mg at pH 6.5 and 55 °C. It displayed the highest thermostability among previously reported IFTases (DFA III forming) and was stable up to 80 °C for 4 h of incubation. The smallest substrate was determined as nystose. The conversion ratio of inulin to DFA III reached 81% when 100 g/L inulin was catalyzed by 80 nM recombinant enzyme for 20 min at pH 6.5 and 55 °C. All of these data indicated that the IFTase (DFA III forming) from Arthrobacter sp. 161MFSha2.1 had great potential for industrial DFA III production.

  8. The importance of dye chemistry and TiCl4 surface treatment in the behavior of Al2O3 recombination barrier layers deposited by atomic layer deposition in solid-state dye-sensitized solar cells

    KAUST Repository

    Brennan, Thomas P.

    2012-01-01

    Atomic layer deposition (ALD) was used to fabricate Al 2O 3 recombination barriers in solid-state dye-sensitized solar cells (ss-DSSCs) employing an organic hole transport material (HTM) for the first time. Al 2O 3 recombination barriers of varying thickness were incorporated into efficient ss-DSSCs utilizing the Z907 dye adsorbed onto a 2 μm-thick nanoporous TiO 2 active layer and the HTM spiro-OMeTAD. The impact of Al 2O 3 barriers was also studied in devices employing different dyes, with increased active layer thicknesses, and with substrates that did not undergo the TiCl 4 surface treatment. In all instances, electron lifetimes (as determined by transient photovoltage measurements) increased and dark current was suppressed after Al 2O 3 deposition. However, only when the TiCl 4 treatment was eliminated did device efficiency increase; in all other instances efficiency decreased due to a drop in short-circuit current. These results are attributed in the former case to the similar effects of Al 2O 3 ALD and the TiCl 4 surface treatment whereas the insulating properties of Al 2O 3 hinder charge injection and lead to current loss in TiCl 4-treated devices. The impact of Al 2O 3 barrier layers was unaffected by doubling the active layer thickness or using an alternative ruthenium dye, but a metal-free donor-π-acceptor dye exhibited a much smaller decrease in current due to its higher excited state energy. We develop a model employing prior research on Al 2O 3 growth and dye kinetics that successfully predicts the reduction in device current as a function of ALD cycles and is extendable to different dye-barrier systems. © This journal is the Owner Societies 2012.

  9. Copper diffusion in Ti-Si-N layers formed by inductively coupled plasma implantation

    International Nuclear Information System (INIS)

    Ee, Y.C.; Chen, Z.; Law, S.B.; Xu, S.; Yakovlev, N.L.; Lai, M.Y.

    2006-01-01

    Ternary Ti-Si-N refractory barrier films of 15 nm thick was prepared by low frequency, high density, inductively coupled plasma implantation of N into Ti x Si y substrate. This leads to the formation of Ti-N and Si-N compounds in the ternary film. Diffusion of copper in the barrier layer after annealing treatment at various temperatures was investigated using time-of-flight secondary ion mass spectrometer (ToF-SIMS) depth profiling, X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and sheet resistance measurement. The current study found that barrier failure did not occur until 650 deg. C annealing for 30 min. The failure occurs by the diffusion of copper into the Ti-Si-N film to form Cu-Ti and Cu-N compounds. FESEM surface morphology and EDX show that copper compounds were formed on the ridge areas of the Ti-Si-N film. The sheet resistance verifies the diffusion of Cu into the Ti-Si-N film; there is a sudden drop in the resistance with Cu compound formation. This finding provides a simple and effective method of monitoring Cu diffusion in TiN-based diffusion barriers

  10. Characterization and frequency of a newly identified HIV-1 BF1 intersubtype circulating recombinant form in São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Neto Walter

    2010-04-01

    Full Text Available Abstract Background HIV circulating recombinant forms (CRFs play an important role in the global and regional HIV epidemics, particularly in regions where multiple subtypes are circulating. To date, several (>40 CRFs are recognized worldwide with five currently circulating in Brazil. Here, we report the characterization of near full-length genome sequences (NFLG of six phylogenetically related HIV-1 BF1 intersubtype recombinants (five from this study and one from other published sequences representing CRF46_BF1. Methods Initially, we selected 36 samples from 888 adult patients residing in São Paulo who had previously been diagnosed as being infected with subclade F1 based on pol subgenomic fragment sequencing. Proviral DNA integrated in peripheral blood mononuclear cells (PBMC was amplified from the purified genomic DNA of all 36-blood samples by five overlapping PCR fragments followed by direct sequencing. Sequence data were obtained from the five fragments that showed identical genomic structure and phylogenetic trees were constructed and compared with previously published sequences. Genuine subclade F1 sequences and any other sequences that exhibited unique mosaic structures were omitted from further analysis Results Of the 36 samples analyzed, only six sequences, inferred from the pol region as subclade F1, displayed BF1 identical mosaic genomes with a single intersubtype breakpoint identified at the nef-U3 overlap (HXB2 position 9347-9365; LTR region. Five of these isolates formed a rigid cluster in phylogentic trees from different subclade F1 fragment regions, which we can now designate as CRF46_BF1. According to our estimate, the new CRF accounts for 0.56% of the HIV-1 circulating strains in São Paulo. Comparison with previously published sequences revealed an additional five isolates that share an identical mosaic structure with those reported in our study. Despite sharing a similar recombinant structure, only one sequence appeared to

  11. Baculoviral expression and characterization of human recombinant PGCP in the form of an active mature dimer and an inactive precursor protein.

    Science.gov (United States)

    Zajc, Tajana; Suban, Dejan; Rajković, Jelena; Dolenc, Iztok

    2011-02-01

    The human-blood plasma glutamate carboxypeptidase (PGCP) is a proteinase that acts on the unsubstituted N- and C-termini of dipeptides. It has been suggested that this PGCP is involved in the release of thyroxine. Furthermore, research has suggested that its activity is up-regulated in hepatitis-C-virus-infected patients with hepatocellular carcinoma. In this study expressed human PGCP in the baculovirus expression system was produced by a Sf9 insect cell line with aim to prepare sufficient amounts of active recombinant enzyme for a subsequent biological characterization. Recombinant PGCP was expressed and secreted into the medium in the form of an inactive proenzyme. It was gradually converted into an active form in the medium after three days, with the highest expression of the active form on day six. The protein was sequentially purified by a combination of various liquid chromatographies, such as hydroxyapatite, ion exchange, and gel chromatography, and as final step with affinity chromatography on Phe-Leu-Sepharose. The human PGCP was purified as an active enzyme in the dimer form and as inactive precursor protein. The dipeptidase activity was confirmed by measuring the hydrolysis of the Ser-Met dipeptide at a slightly acidic pH. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Genetic control of the radiosensitivity of lymphoid cells for antibody-forming ability in CXS series of recombinant inbred mouse strains

    International Nuclear Information System (INIS)

    Okumoto, M.; Mori, N.; Nishikawa, R.; Imai, S.; Hilgers, J.; Takamori, Y.; Yagasaki, O.

    1992-01-01

    Incidence of radiation-induced lymphomas differs remarkably among various mouse strains. BALB/cHeA (C) mice are highly susceptible to radiation induction of lymphomas, while STS/A (S) mice are resistant. Thus, the induction of the disease is controlled by some genetic factors. To examine an involvement of radiosensitivity of lymphoid cells in lymphomagenesis, we have compared genetic control of the radiosensitivity for antibody-forming ability with that of lymphoma development in BALB/cHeA, STS/A, (CXS)F 1 hybrids and CXS series of recombinant inbred strains. Decrease of number of splenic plaque-forming cell (PFC) in Jerne's method by 3 Gy of X-irradiation for BALB/cHeA mice was larger than that for STS/A mice by more than one order of magnitude. (CXS)F 1 hybrid mice showed small number of decrease of PFC similar to STS/A mice suggesting that phenotype of radioresistance was dominant over sensitivity. The best concordance between genetic markers and radiosensitivities of antibody-forming ability in recombinant inbred strains was observed in a region containing Igh locus on chromosome 12. The results show that one locus controlling the radioresistance of lymphoid cells for antibody-forming ability might exist in the region containing Igh locus, and that this region clearly differ from a region with Ifa locus on chromosome 4 which regulate the susceptibility to radiation-induced lymphomagenesis. (author)

  13. Zinc tin oxide as high-temperature stable recombination layer for mesoscopic perovskite/silicon monolithic tandem solar cells

    KAUST Repository

    Werner, Jé ré mie; Walter, Arnaud; Rucavado, Esteban; Moon, Soo Jin; Sacchetto, Davide; Rienaecker, Michael; Peibst, Robby; Brendel, Rolf; Niquille, Xavier; De Wolf, Stefaan; Lö per, Philipp; Morales-Masis, Monica; Nicolay, Sylvain; Niesen, Bjoern; Ballif, Christophe

    2016-01-01

    the concept, we fabricate monolithic tandem cells with mesoscopic top cell with up to 16% efficiency. We then investigate the effect of zinc tin oxide layer thickness variation, showing a strong influence on the optical interference pattern within the tandem

  14. Effect of ultrathin GeOx interfacial layer formed by thermal oxidation on Al2O3 capped Ge

    International Nuclear Information System (INIS)

    Han Le; Zhang Xiong; Wang Sheng-Kai; Xue Bai-Qing; Liu Hong-Gang; Wu Wang-Ran; Zhao Yi

    2014-01-01

    We propose a modified thermal oxidation method in which an Al 2 O 3 capping layer is used as an oxygen blocking layer (OBL) to form an ultrathin GeO x interfacial layer, and obtain a superior Al 2 O 3 /GeO x /Ge gate stack. The GeO x interfacial layer is formed in oxidation reaction by oxygen passing through the Al 2 O 3 OBL, in which the Al 2 O 3 layer could restrain the oxygen diffusion and suppress the GeO desorption during thermal treatment. The thickness of the GeO x interfacial layer would dramatically decrease as the thickness of Al 2 O 3 OBL increases, which is beneficial to achieving an ultrathin GeO x interfacial layer to satisfy the demand for small equivalent oxide thickness (EOT). In addition, the thickness of the GeO x interfacial layer has little influence on the passivation effect of the Al 2 O 3 /Ge interface. Ge (100) p-channel metal–oxide–semiconductor field-effect transistors (pMOSFETs) using the Al 2 O 3 /GeO x /Ge gate stacks exhibit excellent electrical characteristics; that is, a drain current on-off (I on /I off ) ratio of above 1×10 4 , a subthreshold slope of ∼ 120 mV/dec, and a peak hole mobility of 265 cm 2 /V·s are achieved. (condensed matter: structural, mechanical, and thermal properties)

  15. Friend and Moloney murine leukemia viruses specifically recombine with different endogenous retroviral sequences to generate mink cell focus-forming viruses.

    Science.gov (United States)

    Evans, L H; Cloyd, M W

    1985-01-01

    A group of mink cell focus-forming (MCF) viruses was derived by inoculation of NFS/N mice with Moloney murine leukemia virus (Mo-MuLV 1387) and was compared to a similarly derived group of MCF viruses from mice inoculated with Friend MuLV (Fr-MuLV 57). Antigenic analyses using monoclonal antibodies specific for MCF virus and xenotropic MuLV envelope proteins and genomic structural analyses by RNase T1-resistant oligonucleotide finger-printing indicated that the Moloney and Friend MCF viruses arose by recombination of the respective ecotropic MuLVs with different endogenous retrovirus sequences of NFS mice.

  16. Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion

    Directory of Open Access Journals (Sweden)

    Maria Isabel Dantas de MEDEIROS

    2016-01-01

    Full Text Available Abstract The layer formed by fluoride compounds on tooth surface is important to protect the underlying enamel from erosion. However, there is no investigation into the properties of protective layer formed by NaF and TiF4 varnishes on eroded enamel. This study aimed to evaluate the thickness, topography, nanohardness, and elastic modulus of the protective layer formed by NaF and TiF4 varnishes on enamel after erosion using nanoindentation and atomic force microscopy (AFM. Human enamel specimens were sorted into control, NaF, and TiF4 varnish groups (n = 10. The initial nanohardness and elastic modulus values were obtained and varnishes were applied to the enamel and submitted to erosive challenge (10 cycles: 5 s cola drink/5 s artificial saliva. Thereafter, nanohardness and elastic modulus were measured. Both topography and thickness were evaluated by AFM. The data were subjected to ANOVA, Tukey’s test and Student’s t test (α = 0.05. After erosion, TiF4 showed a thicker protective layer compared to the NaF group and nanohardness and elastic modulus values were significantly lower than those of the control group. It was not possible to measure nanohardness and elastic modulus in the NaF group due to the thin protective layer formed. AFM showed globular deposits, which completely covered the eroded surface in the TiF4 group. After erosive challenge, the protective layer formed by TiF4 varnish showed significant properties and it was thicker than the layer formed by NaF varnish.

  17. XPS studies of SiO/sub 2/ surface layers formed by oxygen ion implantation into silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, D.; Finster, J. (Karl-Marx-Universitaet, Leipzig (German Democratic Republic). Sektion Chemie); Hensel, E.; Skorupa, W.; Kreissig, U. (Zentralinstitut fuer Kernforschung, Rossendorf bei Dresden (German Democratic Republic))

    1983-03-16

    SiO/sub 2/ surface layers of 160 nm thickness formed by /sup 16/O/sup +/ ion implantation into silicon are examined by X-ray photoelectron spectroscopy measurements into the depth after a step-by-step chemical etching. The chemical nature and the thickness of the transition layer were determined. The results of the XPS measurements show that the outer surface and the bulk of the layers formed by oxygen implantation and subsequent high temperature annealing consist of SiO/sub 2/. There is no evidence for Si or SiO/sub x/ (0layers. Only its thickness is somewhat larger than in thermal oxide.

  18. Complementary study of the internal porous silicon layers formed under high-dose implantation of helium ions

    Energy Technology Data Exchange (ETDEWEB)

    Lomov, A. A., E-mail: lomov@ftian.ru; Myakon’kikh, A. V. [Russian Academy of Sciences, Institute of Physics and Technology (Russian Federation); Chesnokov, Yu. M. [National Research Centre “Kurchatov Institute” (Russian Federation); Shemukhin, A. A.; Oreshko, A. P. [Moscow State University (Russian Federation)

    2017-03-15

    The surface layers of Si(001) substrates subjected to plasma-immersion implantation of helium ions with an energy of 2–5 keV and a dose of 5 × 10{sup 17} cm{sup –2} have been investigated using high-resolution X-ray reflectivity, Rutherford backscattering, and transmission electron microscopy. The electron density depth profile in the surface layer formed by helium ions is obtained, and its elemental and phase compositions are determined. This layer is found to have a complex structure and consist of an upper amorphous sublayer and a layer with a porosity of 30–35% beneath. It is shown that the porous layer has the sharpest boundaries at a lower energy of implantable ions.

  19. Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

    Energy Technology Data Exchange (ETDEWEB)

    Shen, H.H.; Liu, L.; Liu, X.Z.; Guo, Q.; Meng, T.X.; Wang, Z.X.; Yang, H.J.; Liu, X.P., E-mail: liuxiaoping@tyut.edu.cn

    2016-12-01

    Highlights: • A Zr/ZrC modified layer was formed on AISI 440B stainless steel using plasma surface Zr-alloying. • The thickness of the modified layer increases with alloying temperature and time. • Formation mechanism of the modified layer is dependent on the mutual diffusion of Zr and substrate elements. • The modified surface shows an improved wear resistance. - Abstract: The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

  20. UN{sub 2−x} layer formed on uranium metal by glow plasma nitriding

    Energy Technology Data Exchange (ETDEWEB)

    Long, Zhong [China Academy of Engineering Physics, P.O. Box 919-71, Mianyang 621907 (China); Hu, Yin [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Chen, Lin [China Academy of Engineering Physics, P.O. Box 919-71, Mianyang 621907 (China); Luo, Lizhu [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Liu, Kezhao, E-mail: liukz@hotmail.com [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Lai, Xinchun, E-mail: lai319@yahoo.com [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China)

    2015-01-25

    Highlights: • We used a very simple method to prepare nitride layer on uranium metal surface. • This modified layer is nitrogen-rich nitride, which should be written as UN{sub 2−x}. • TEM images show the nitride layer is composed of nano-sized grains. • XPS analysis indicates there is uranium with abnormal low valence in the nitride. - Abstract: Glow plasma nitriding is a simple and economical surface treatment method, and this technology was used to prepare nitride layer on the surface of uranium metal with thickness of several microns. The composition and structure of the nitride layer were analyzed by AES and XRD, indicating that this modified layer is nitrogen-rich uranium nitride, which should be written as UN{sub 2−x}. TEM images show the nitride layer is composed of nano-sized grains, with compact structure. And XPS analysis indicates there is uranium with abnormal low valence existing in the nitride. After the treated uranium storage in air for a long time, oxygen just entered the surface several nanometers, showing the nitride layer has excellent oxidation resistance. The mechanism of nitride layer formation and low valence uranium appearance is discussed.

  1. UN2−x layer formed on uranium metal by glow plasma nitriding

    International Nuclear Information System (INIS)

    Long, Zhong; Hu, Yin; Chen, Lin; Luo, Lizhu; Liu, Kezhao; Lai, Xinchun

    2015-01-01

    Highlights: • We used a very simple method to prepare nitride layer on uranium metal surface. • This modified layer is nitrogen-rich nitride, which should be written as UN 2−x . • TEM images show the nitride layer is composed of nano-sized grains. • XPS analysis indicates there is uranium with abnormal low valence in the nitride. - Abstract: Glow plasma nitriding is a simple and economical surface treatment method, and this technology was used to prepare nitride layer on the surface of uranium metal with thickness of several microns. The composition and structure of the nitride layer were analyzed by AES and XRD, indicating that this modified layer is nitrogen-rich uranium nitride, which should be written as UN 2−x . TEM images show the nitride layer is composed of nano-sized grains, with compact structure. And XPS analysis indicates there is uranium with abnormal low valence existing in the nitride. After the treated uranium storage in air for a long time, oxygen just entered the surface several nanometers, showing the nitride layer has excellent oxidation resistance. The mechanism of nitride layer formation and low valence uranium appearance is discussed

  2. Analytic Closed-Form Solution of a Mixed Layer Model for Stratocumulus Clouds

    Science.gov (United States)

    Akyurek, Bengu Ozge

    Stratocumulus clouds play an important role in climate cooling and are hard to predict using global climate and weather forecast models. Thus, previous studies in the literature use observations and numerical simulation tools, such as large-eddy simulation (LES), to solve the governing equations for the evolution of stratocumulus clouds. In contrast to the previous works, this work provides an analytic closed-form solution to the cloud thickness evolution of stratocumulus clouds in a mixed-layer model framework. With a focus on application over coastal lands, the diurnal cycle of cloud thickness and whether or not clouds dissipate are of particular interest. An analytic solution enables the sensitivity analysis of implicitly interdependent variables and extrema analysis of cloud variables that are hard to achieve using numerical solutions. In this work, the sensitivity of inversion height, cloud-base height, and cloud thickness with respect to initial and boundary conditions, such as Bowen ratio, subsidence, surface temperature, and initial inversion height, are studied. A critical initial cloud thickness value that can be dissipated pre- and post-sunrise is provided. Furthermore, an extrema analysis is provided to obtain the minima and maxima of the inversion height and cloud thickness within 24 h. The proposed solution is validated against LES results under the same initial and boundary conditions. Then, the proposed analytic framework is extended to incorporate multiple vertical columns that are coupled by advection through wind flow. This enables a bridge between the micro-scale and the mesoscale relations. The effect of advection on cloud evolution is studied and a sensitivity analysis is provided.

  3. Angular behavior of the Berreman effect investigated in uniform Al2O3 layers formed by atomic layer deposition.

    Science.gov (United States)

    Scarel, Giovanna; Na, Jeong-Seok; Parsons, Gregory N

    2010-04-21

    Experimental transmission absorbance infrared spectra of γ-Al(2)O(3) showing evidence of the angular dependence of the peaks of surface modes appearing next to the longitudinal optical phonon frequency ω(LO) (the Berreman effect) are collected from heat-treated thin oxide films deposited with thickness uniformity on Si(100) using atomic layer deposition. The peak area of the most intense surface longitudinal optical mode is plotted versus the infrared beam incidence angle θ(0). The experimental points closely follow the sin(4)(θ(0)) function in a broad thickness range. The best match occurs at a critical thickness, where a linear relationship exists between the surface longitudinal optical mode intensity and film thickness. Simulations suggest that below the critical thickness the sin(4)(θ(0)) behavior can be explained by refraction phenomena at the air/thin film and thin film/substrate interfaces. Above the critical thickness, the experimentally obtained result is derived from field boundary conditions at the air/thin film interface. The sin(4)(θ(0)) functional trend breaks down far above the critical thickness. This picture indicates that infrared radiation has a limited penetration depth into the oxide film, similarly to electromagnetic waves in conductors. Consequently, surface longitudinal optical modes are viewed as bulk phonons excited down to the penetration depth of the infrared beam. Comparison with simulated data suggests that the infrared radiation absorptance of surface longitudinal optical modes tends to approach the sin(2)(θ(0)) trend. Reflection phenomena are considered to be the origin of the deviation from the sin(4)(θ(0)) trend related to refraction.

  4. Decreased Charge Transport Barrier and Recombination of Organic Solar Cells by Constructing Interfacial Nanojunction with Annealing-Free ZnO and Al Layers.

    Science.gov (United States)

    Liu, Chunyu; Zhang, Dezhong; Li, Zhiqi; Zhang, Xinyuan; Guo, Wenbin; Zhang, Liu; Ruan, Shengping; Long, Yongbing

    2017-07-05

    To overcome drawbacks of the electron transport layer, such as complex surface defects and unmatched energy levels, we successfully employed a smart semiconductor-metal interfacial nanojunciton in organic solar cells by evaporating an ultrathin Al interlayer onto annealing-free ZnO electron transport layer, resulting in a high fill factor of 73.68% and power conversion efficiency of 9.81%. The construction of ZnO-Al nanojunction could effectively fill the surface defects of ZnO and reduce its work function because of the electron transfer from Al to ZnO by Fermi level equilibrium. The filling of surface defects decreased the interfacial carrier recombination in midgap trap states. The reduced surface work function of ZnO-Al remodulated the interfacial characteristics between ZnO and [6,6]-phenyl C71-butyric acid methyl ester (PC 71 BM), decreasing or even eliminating the interfacial barrier against the electron transport, which is beneficial to improve the electron extraction capacity. The filled surface defects and reduced interfacial barrier were realistically observed by photoluminescence measurements of ZnO film and the performance of electron injection devices, respectively. This work provides a simple and effective method to simultaneously solve the problems of surface defects and unmatched energy level for the annealing-free ZnO or other metal oxide semiconductors, paving a way for the future popularization in photovoltaic devices.

  5. Electrochemically formed passive layers on titanium - preparation and biocompatibility assessment in Hank's balanced salt solution

    International Nuclear Information System (INIS)

    Zhao, B.; Jerkiewicz, G.

    2006-01-01

    Uniform and crack-free passive layers on Ti are prepared using AC voltage in 7.5 wt.% aq. NH 4 ·BF 4 at 25 o C. The passive layers possess coloration (wide spectrum of colors) that depends on the experimental conditions. The biocompatibility of such prepared passive layers is evaluated using corrosion science and analytical techniques. Their corrosion behavior, Ti-ion release, surface roughness, and wettability in Hank's Balanced Salt Solution (HBSS) at 37 o C are the main focus of this work. Open-circuit potential and polarization measurements demonstrate that the corrosion potential (E corr ) of the passive layers becomes more positive than that of the untreated Ti. The value of E corr increases as we increase the AC voltage (VAC). Their corrosion rate (CR) is lower than that of the untreated Ti, and they reduced the Ti-ion release level from 230 to 15 ppb. An increase in the AC voltage frequency (f) leads to a slightly higher level of the Ti-ion release (∼50 ppb). Surface profilometry, optical microscopy, and scanning electron microscopy (SEM) analyses show that prolonged exposure of the passive layers to HBSS results in changes to their surface topography. The passive layers prepared by the application of AC voltage are rougher and more hydrophilic than the untreated Ti. Our methodology of preparing biocompatible passive layers on Ti might be applied as a new surface treatment procedure for Ti implants. (author)

  6. Simultaneous sound velocity and thickness measurement by the ultrasonic pitch-catch method for corrosion-layer-forming polymeric materials.

    Science.gov (United States)

    Kusano, Masahiro; Takizawa, Shota; Sakai, Tetsuya; Arao, Yoshihiko; Kubouchi, Masatoshi

    2018-01-01

    Since thermosetting resins have excellent resistance to chemicals, fiber reinforced plastics composed of such resins and reinforcement fibers are widely used as construction materials for equipment in chemical plants. Such equipment is usually used for several decades under severe corrosive conditions so that failure due to degradation may result. One of the degradation behaviors in thermosetting resins under chemical solutions is "corrosion-layer-forming" degradation. In this type of degradation, surface resins in contact with a solution corrode, and some of them remain asa corrosion layer on the pristine part. It is difficult to precisely measure the thickness of the pristine part of such degradation type materials by conventional pulse-echo ultrasonic testing, because the sound velocity depends on the degree of corrosion of the polymeric material. In addition, the ultrasonic reflection interface between the pristine part and the corrosion layer is obscure. Thus, we propose a pitch-catch method using a pair of normal and angle probes to measure four parameters: the thicknesses of the pristine part and the corrosion layer, and their respective sound velocities. The validity of the proposed method was confirmed by measuring a two-layer sample and a sample including corroded parts. The results demonstrate that the pitch-catch method can successfully measure the four parameters and evaluate the residual thickness of the pristine part in the corrosion-layer-forming sample. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Isolation and characterization of a replication-competent molecular clone of an HIV-1 circulating recombinant form (CRF33_01B.

    Directory of Open Access Journals (Sweden)

    Kok Keng Tee

    Full Text Available A growing number of emerging HIV-1 recombinants classified as circulating recombinant forms (CRFs have been identified in Southeast Asia in recent years, establishing a molecular diversity of increasing complexity in the region. Here, we constructed a replication-competent HIV-1 clone for CRF33_01B (designated p05MYKL045.1, a newly identified recombinant comprised of CRF01_AE and subtype B. p05MYKL045.1 was reconstituted by cloning of the near full-length HIV-1 sequence from a newly-diagnosed individual presumably infected heterosexually in Kuala Lumpur, Malaysia. The chimeric clone, which contains the 5' LTR (long terminal repeat region of p93JP-NH1 (a previously isolated CRF01_AE infectious clone, showed robust viral replication in the human peripheral blood mononuclear cells. This clone demonstrated robust viral propagation and profound syncytium formation in CD4+, CXCR4-expressing human glioma NP-2 cells, indicating that p05MYKL045.1 is a CXCR4-using virus. Viral propagation, however, was not detected in various human T cell lines including MT-2, M8166, Sup-T1, H9, Jurkat, Molt-4 and PM1. p05MYKL045.1 appears to proliferate only in restricted host range, suggesting that unknown viral and/or cellular host factors may play a role in viral infectivity and replication in human T cell lines. Availability of a CRF33_01B molecular clone will be useful in facilitating the development of vaccine candidates that match the HIV-1 strains circulating in Southeast Asia.

  8. Minimizing performance degradation induced by interfacial recombination in perovskite solar cells through tailoring of the transport layer electronic properties

    Directory of Open Access Journals (Sweden)

    Liang Xu

    2018-03-01

    Full Text Available The performance of hybrid organic-inorganic metal halide perovskite solar cells is investigated using one-dimensional drift-diffusion device simulations. We study the effects of interfacial defect density, doping concentration, and electronic level positions of the charge transport layer (CTL. Choosing CTLs with a favorable band alignment, rather than passivating CTL-perovskite interfacial defects, is shown to be beneficial for maintaining high power-conversion efficiency, due to reduced minority carrier density arising from a favorable local electric field profile. Insights from this study provide theoretical guidance on practical selection of CTL materials for achieving high-performance perovskite solar cells.

  9. Ultra thin buried oxide layers formed by low dose Simox process

    Energy Technology Data Exchange (ETDEWEB)

    Aspar, B.; Pudda, C.; Papon, A.M. [CEA Centre d`Etudes de Grenoble, 38 (France). Lab. d`Electronique et d`Instrumentation; Auberton Herve, A.J.; Lamure, J.M. [SOITEC, 38 - Grenoble (France)

    1994-12-31

    Oxygen low dose implantation is studied for two implantation energies. For 190 keV, a continuous buried oxide layer is obtained with a high dislocation density in the top silicon layer due to SiO{sub 2} precipitates. For 120 keV, this silicon layer is free of SiO{sub 2} precipitate and has a low dislocation density. Low density of pin-holes is observed in the buried oxide. The influence of silicon islands in the buried oxide on the breakdown electric fields is discussed. (authors). 6 refs., 5 figs.

  10. Ultra thin buried oxide layers formed by low dose Simox process

    International Nuclear Information System (INIS)

    Aspar, B.; Pudda, C.; Papon, A.M.

    1994-01-01

    Oxygen low dose implantation is studied for two implantation energies. For 190 keV, a continuous buried oxide layer is obtained with a high dislocation density in the top silicon layer due to SiO 2 precipitates. For 120 keV, this silicon layer is free of SiO 2 precipitate and has a low dislocation density. Low density of pin-holes is observed in the buried oxide. The influence of silicon islands in the buried oxide on the breakdown electric fields is discussed. (authors). 6 refs., 5 figs

  11. Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

    Science.gov (United States)

    Shen, H. H.; Liu, L.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

    2016-12-01

    The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

  12. Effect of low dose electron beam irradiation on the alteration layer formed during nuclear glass leaching

    Energy Technology Data Exchange (ETDEWEB)

    Mougnaud, S., E-mail: sarah.mougnaud@gmail.com [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Tribet, M. [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Renault, J.-P. [NIMBE, CNRS, CEA, Université Paris Saclay, CEA Saclay, 91191 Gif-sur-Yvette cedex (France); Jollivet, P. [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Panczer, G. [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex (France); Charpentier, T. [NIMBE, CNRS, CEA, Université Paris Saclay, CEA Saclay, 91191 Gif-sur-Yvette cedex (France); Jégou, C. [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France)

    2016-12-15

    This investigation concerns borosilicate glass leaching mechanisms and the evolution of alteration layer under electron beam irradiation. A simple glass doped with rare earth elements was selected in order to access mechanistic and structural information and better evaluate the effects of irradiation. It was fully leached in initially pure water at 90 °C and at high glass surface area to solution volume ratio (S/V = 20 000 m{sup −1}) in static conditions. Under these conditions, the system quickly reaches the residual alteration rate regime. A small particle size fraction (2–5 μm) was sampled in order to obtain a fairly homogeneous altered material enabling the use of bulk characterization methods. External irradiations with 10 MeV electrons up to a dose of 10 MGy were performed either before or after leaching, to investigate respectively the effect of initial glass irradiation on its alteration behavior and the irradiation stability of the alteration layer. Glass dissolution rate was analyzed by regular leachate samplings and the alteration layer structure was characterized by Raman, luminescence (continuous or time-resolved), and {sup 29}Si MAS NMR and EPR spectroscopy. It was shown that the small initial glass evolutions under irradiation did not induce any modification of the leaching kinetic nor of the structure of the alteration layer. The alteration process seemed to “smooth over” the created defects. Otherwise, the alteration layer and initial glass appeared to have different behaviors under irradiation. No Eu{sup 3+} reduction was detected in the alteration layer after irradiation and the defect creation efficiency was much lower than for initial glass. This can possibly be explained by the protective role of pore water contained in the altered material (∼20%). Moreover, a slight depolymerization of the silicon network of the altered glass under irradiation with electrons was evidenced, whereas in the initial glass it typically

  13. Properties of deposited layer formed by interaction with Be seeded D–He mixture plasma and tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, K., E-mail: tokunaga@riam.kyushu-u.ac.jp [Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Baldwin, M.J.; Nishijima, D.; Doerner, R.P. [Center for Energy Research, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417 (United States); Nagata, S. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tsuchiya, B. [Department of General Education, Faculty of Science and Technology, Meiji University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya, 468-8502 (Japan); Kurishita, H. [International Research Center for Nuclear Materials Science, IMR, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Fujiwara, T.; Araki, K.; Miyamoto, Y. [Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Ohno, N. [School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Ueda, Y. [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

    2013-11-15

    Be-seeded, high-flux, deuterium/helium mixture plasma exposure experiments on tungsten target materials have been performed to simulate ITER all tungsten divertor erosion/modification and deposition phenomena. The exposure conditions are kept fixed at a typical low-ion-energy of 60 eV and a flux of 3–6 × 10{sup 22}/m{sup 2}/s. Sample temperature is 1123 K and plasma exposure times spanning 1050–10,100 s are explored. The typical ratio of He/D ions is 0.2 and Be content is 0.2%. A He-induced nanostructure layer is formed on the exposure surfaces of tungsten materials and the surface of the nanostructure is covered by a thin layer of Be and O. A fraction of the re-eroded Be from the target is deposited on a glassy carbon plate with line of sight to the tungsten target. Rutherford backscattering spectrometry analyses show that the Be redeposit layer is in the form of laminae. Small amounts of Mo, W and C are also found in the redeposited Be layer. Elastic recoil detection analyses show that D, He and H are also included in the redeposited Be layer.

  14. The Influence of the Tool Surface Texture on Friction and the Surface Layers Properties of Formed Component

    Directory of Open Access Journals (Sweden)

    Jana Šugárová

    2018-03-01

    Full Text Available The morphological texturing of forming tool surfaces has high potential to reduce friction and tool wear and also has impact on the surface layers properties of formed material. In order to understand the effect of different types of tool textures, produced by nanosecond fibre laser, on the tribological conditions at the interface tool-formed material and on the integrity of formed part surface layers, the series of experimental investigations have been carried out. The coefficient of friction for different texture parameters (individual feature shape, including the depth profile of the cavities and orientation of the features relative to the material flow was evaluated via a Ring Test and the surface layers integrity of formed material (surface roughness and subsurface micro hardness was also experimentally analysed. The results showed a positive effect of surface texturing on the friction coefficients and the strain hardening of test samples material. Application of surface texture consisting of dimple-like depressions arranged in radial layout contributed to the most significant friction reduction of about 40%. On the other hand, this surface texture contributed to the increase of surface roughness parameters, Ra parameter increased from 0.49 μm to 2.19 μm and the Rz parameter increased from 0.99 μm to 16.79 μm.

  15. Characteristics of Ni-based coating layer formed by laser and plasma cladding processes

    International Nuclear Information System (INIS)

    Xu Guojian; Kutsuna, Muneharu; Liu Zhongjie; Zhang Hong

    2006-01-01

    The clad layers of Ni-based alloy were deposited on the SUS316L stainless plates by CO 2 laser and plasma cladding processes. The smooth clad bead was obtained by CO 2 laser cladding process. The phases of clad layer were investigated by an optical microscope, scanning electron microscopy (SEM), X-ray diffractometer (XRD), electron probe microanalysis (EPMA) and energy-dispersive spectrometer (EDS). The microstructures of clad layers belonged to a hypereutectic structure. Primary phases consist of boride CrB and carbide Cr 7 C 3 . The eutectic structure consists of Ni + CrB or Ni + Cr 7 C 3 . Compared with the plasma cladding, the fine microstructures, low dilutions, high Vickers hardness and excellent wear resistance were obtained by CO 2 laser cladding. All that show the laser cladding process has a higher efficiency and good cladding quality

  16. Binding properties of a streptavidin layer formed on a biotinylated Langmuir–Schaefer film of unfolded protein

    Energy Technology Data Exchange (ETDEWEB)

    Furuno, Taiji, E-mail: t_furuno@a8.keio.jp

    2016-04-01

    A Langmuir monolayer of carbonic anhydrase (CA) unfolded at an air/water interface was transferred onto the hydrophobic surface of a silicon wafer by means of the Langmuir–Schaefer technique. The transferred CA film was biotinylated and was incubated in a streptavidin (SAv) solution to obtain a densely packed SAv layer by biotin–SAv linkage. Biotinylated proteins including ferritin, catalase, alcohol dehydrogenase, and carbonic anhydrase were incubated with the SAv layer and binding of these proteins was examined by atomic force microscopy. High-density binding of the biotinylated proteins was observed, whereas the amount of adsorbed non-biotinylated proteins was low or negligible. The SAv layer on the Langmuir–Schaefer film of unfolded protein could become a basic architecture for protein immobilization studies. - Highlights: • Langmuir–Schaefer film of carbonic anhydrase (LSF-CA) was biotinylated. • A densely packed streptavidin (SAv) layer was formed on the biotinylated LSF-CA. • Biotinylated proteins were bound to the SAv layer at high density. • Nonspecific adsorption of intact proteins to the SAv layer was weak. • Atomic force microscopy showed the binding of proteins at molecular resolution.

  17. Recombinant HA1 produced in E. coli forms functional oligomers and generates strain-specific SRID potency antibodies for pandemic influenza vaccines.

    Science.gov (United States)

    Khurana, Surender; Larkin, Christopher; Verma, Swati; Joshi, Manju B; Fontana, Juan; Steven, Alasdair C; King, Lisa R; Manischewitz, Jody; McCormick, William; Gupta, Rajesh K; Golding, Hana

    2011-08-05

    Vaccine production and initiation of mass vaccination is a key factor in rapid response to new influenza pandemic. During the 2009-2010 H1N1 pandemic, several bottlenecks were identified, including the delayed availability of vaccine potency reagents. Currently, antisera for the single-radial immunodiffusion (SRID) potency assay are generated in sheep immunized repeatedly with HA released and purified after bromelain-treatment of influenza virus grown in eggs. This approach was a major bottleneck for pandemic H1N1 (H1N1pdm09) potency reagent development in 2009. Alternative approaches are needed to make HA immunogens for generation of SRID reagents in the shortest possible time. In this study, we found that properly folded recombinant HA1 globular domain (rHA1) from several type A viruses including H1N1pdm09 and two H5N1 viruses could be produced efficiently using a bacterial expression system and subsequent purification. The rHA1 proteins were shown to form functional oligomers of trimers, similar to virus derived HA, and elicited high titer of neutralizing antibodies in rabbits and sheep. Importantly, the immune sera formed precipitation rings with reference antigens in the SRID assay in a dose-dependent manner. The HA contents in multiple H1N1 vaccine products from different manufacturers (and in several lots) as determined with the rHA1-generated sheep sera were similar to the values obtained with a traditionally generated sheep serum from NIBSC. We conclude that bacterially expressed recombinant HA1 proteins can be produced rapidly and used to generate SRID potency reagents shortly after new influenza strains with pandemic potential are identified. Published by Elsevier Ltd.

  18. Method of forming a leak proof plasma sprayed interconnection layer on an electrode of an electrochemical cell

    Science.gov (United States)

    Kuo, Lewis J. H.; Vora, Shailesh D.

    1995-01-01

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an electrode structure of an electrochemical cell by: (A) providing an electrode structure; (B) forming on a selected portion of the electrode surface, an interconnection layer having the general formula La.sub.1-x M.sub.x Cr.sub.1-y N.sub.y O.sub.3, where M is a dopant selected from the group of Ca, Sr, Ba, and mixtures thereof, and where N is a dopant selected from the group of Mg, Co, Ni, Al, and mixtures thereof, and where x and y are each independently about 0.075-0.25, by thermally spraying, preferably plasma arc spraying, a flux added interconnection spray powder, preferably agglomerated, the flux added powder comprising flux particles, preferably including dopant, preferably (CaO).sub.12. (Al.sub.2 O.sub.3).sub.7 flux particles including Ca and Al dopant, and LaCrO.sub.3 interconnection particles, preferably undoped LaCrO.sub.3, to form a dense and substantially gas-tight interconnection material bonded to the electrode structure by a single plasma spraying step; and, (C) heat treating the interconnection layer at from about 1200.degree. to 1350.degree. C. to further densify and heal the micro-cracks and macro-cracks of the thermally sprayed interconnection layer. The result is a substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode structure. The electrode structure can be an air electrode, and a solid electrolyte layer can be applied to the unselected portion of the air electrode, and further a fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell for generation of electrical power.

  19. Comparison of various methods of measuring thin oxide layers formed on molybdenum and titanium

    International Nuclear Information System (INIS)

    Lepage, F.; Bardolle, J.; Boulben, J.M.

    1975-01-01

    The problem of the growth of thin layers is very interesting from both the fundamental and technological viewpoints. This work deals with oxide films produced on two metals, molybdenum and titanium. The thicknesses obtained by various methods (microgravimetry, nuclear reactions and spectrophotometry) are compared and the advantages and disadvantages of each method are shown [fr

  20. Electrochemical Evaluation of Corrosion Inhibiting Layers Formed in a Defect from Lithium-Leaching Organic Coatings

    NARCIS (Netherlands)

    Visser, P.; Meeusen, M.; Gonzalez Garcia, Y.; Terryn, H.A.; Mol, J.M.C.

    2017-01-01

    This work presents the electrochemical evaluation of protective layers generated in a coating defect from lithium-leaching organic coatings on AA2024-T3 aluminum alloys as a function of neutral salt spray exposure time. Electrochemical impedance spectroscopy was used to study the electrochemical

  1. Copper Benzenetricarboxylate Metal-Organic Framework Nucleation Mechanisms on Metal Oxide Powders and Thin Films formed by Atomic Layer Deposition.

    Science.gov (United States)

    Lemaire, Paul C; Zhao, Junjie; Williams, Philip S; Walls, Howard J; Shepherd, Sarah D; Losego, Mark D; Peterson, Gregory W; Parsons, Gregory N

    2016-04-13

    Chemically functional microporous metal-organic framework (MOF) crystals are attractive for filtration and gas storage applications, and recent results show that they can be immobilized on high surface area substrates, such as fiber mats. However, fundamental knowledge is still lacking regarding initial key reaction steps in thin film MOF nucleation and growth. We find that thin inorganic nucleation layers formed by atomic layer deposition (ALD) can promote solvothermal growth of copper benzenetricarboxylate MOF (Cu-BTC) on various substrate surfaces. The nature of the ALD material affects the MOF nucleation time, crystal size and morphology, and the resulting MOF surface area per unit mass. To understand MOF nucleation mechanisms, we investigate detailed Cu-BTC MOF nucleation behavior on metal oxide powders and Al2O3, ZnO, and TiO2 layers formed by ALD on polypropylene substrates. Studying both combined and sequential MOF reactant exposure conditions, we find that during solvothermal synthesis ALD metal oxides can react with the MOF metal precursor to form double hydroxy salts that can further convert to Cu-BTC MOF. The acidic organic linker can also etch or react with the surface to form MOF from an oxide metal source, which can also function as a nucleation agent for Cu-BTC in the mixed solvothermal solution. We discuss the implications of these results for better controlled thin film MOF nucleation and growth.

  2. A nitride-based epitaxial surface layer formed by ammonia treatment of silicene-terminated ZrB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wiggers, F. B., E-mail: F.B.Wiggers@utwente.nl; Van Bui, H.; Schmitz, J.; Kovalgin, A. Y.; Jong, M. P. de [MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede (Netherlands); Friedlein, R.; Yamada-Takamura, Y. [School of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1292 (Japan)

    2016-04-07

    We present a method for the formation of an epitaxial  surface layer involving B, N, and Si atoms on a ZrB{sub 2}(0001) thin film on Si(111). It has the potential to be an insulating growth template for 2D semiconductors. The chemical reaction of NH{sub 3} molecules with the silicene-terminated ZrB{sub 2}  surface was characterized by synchrotron-based, high-resolution core-level photoelectron spectroscopy and low-energy electron diffraction. In particular, the dissociative chemisorption of NH{sub 3} at 400 °C leads to surface  nitridation, and subsequent annealing up to 830 °C results in a solid phase reaction with the ZrB{sub 2} subsurface layers. In this way, a new nitride-based epitaxial  surface layer is formed with hexagonal symmetry and a single in-plane crystal orientation.

  3. In silico, in vitro and antifungal activity of the surface layers formed on zinc during this biomaterial degradation

    Science.gov (United States)

    Alves, Marta M.; Marques, Luísa M.; Nogueira, Isabel; Santos, Catarina F.; Salazar, Sara B.; Eugénio, Sónia; Mira, Nuno P.; Montemor, M. F.

    2018-07-01

    Zinc (Zn) has been proposed as an alternative metallic biodegradable material to support transient wound-healing processes. Once a Zn piece is implanted inside the organism the degradation will depend upon the physiological surrounding environment. This, by modulating the composition of the surface layers formed on Zn devices, will govern the subsequent interactions with the surrounding living cells (e.g. biocompatibility and/or antifungal behaviour). In silico simulation of an implanted Zn piece at bone-muscle interface or inside the bone yielded the preferential precipitation of simonkolleite or zincite, respectively. To study the impact of these surface layers in the in vitro behaviour of Zn biomaterials, simonkolleite and zincite where synthesised. The successful production of simonkolleite or zincite was confirmed by an extensive physicochemical characterization. An in vitro layer formed on the top of these surface layers revealed that simonkolleite was rather inert, while zincite yielded a complex matrix containing hydroxyapatite, an important bone analogue. When analysing the "anti-biofilm" activity simonkolleite stood out for its activity against an important pathogenic fungi involved in implant-device infections, Candida albicans. The possible physiological implications of these findings are discussed.

  4. Kinetics of boride layers formed on the surface of AISI 4140 steel

    International Nuclear Information System (INIS)

    Sen, S.; Sen, U.; Bindal, C.

    2004-01-01

    The present study reports on boride layer growth kinetics of borided AISI 4140 steel. Steels were boronized in molten borax, boric acid and ferro-silicon bath at 1123 K 1173 K and 1223 K for 2, 4, 6 and 8 hours. Boride layer thickness ranged from 38.4 to 225 μm. Layer growth kinetics were analysed by measuring the extent of penetration of FeB and Fe 2 B sublayers as a function of boronizing time and temperature in the range of 1123-1223 K. The depth of the tips of the most deeply penetrated FeB and Fe 2 B needles are taken as measures for diffusion in the fast directions. The kinetics of the reaction, K=K 0 exp(-Q/RT) have also been determined by varying the boriding temperature and time. The results showed that K increase with boronizing temperature. Activation energy (Q) for present study was determined as 215 kj.mol -1 . The diffusion coefficient (K) ranged from 3 x 10 -9 cm 2 s -1 to 2 x 10 -8 cm 2 s -1 . Also temperature-dependent constant (K 0 ) at temperatures 1123 K, 1173 K and 1223 K was 179.4 cm 2 s -1 . (orig.)

  5. Kinetics of boride layers formed on the surface of AISI 4140 steel

    Energy Technology Data Exchange (ETDEWEB)

    Sen, S.; Sen, U. [Sakarya Univ., Dept. of Metal Education, Sakarya (Turkey); Bindal, C. [Sakarya Univ., Dept. of Materials and Metallurgy, Sakarya (Turkey)

    2004-07-01

    The present study reports on boride layer growth kinetics of borided AISI 4140 steel. Steels were boronized in molten borax, boric acid and ferro-silicon bath at 1123 K 1173 K and 1223 K for 2, 4, 6 and 8 hours. Boride layer thickness ranged from 38.4 to 225 {mu}m. Layer growth kinetics were analysed by measuring the extent of penetration of FeB and Fe{sub 2}B sublayers as a function of boronizing time and temperature in the range of 1123-1223 K. The depth of the tips of the most deeply penetrated FeB and Fe{sub 2}B needles are taken as measures for diffusion in the fast directions. The kinetics of the reaction, K=K{sub 0} exp(-Q/RT) have also been determined by varying the boriding temperature and time. The results showed that K increase with boronizing temperature. Activation energy (Q) for present study was determined as 215 kj.mol{sup -1}. The diffusion coefficient (K) ranged from 3 x 10{sup -9} cm{sup 2}s{sup -1} to 2 x 10{sup -8} cm{sup 2}s{sup -1}. Also temperature-dependent constant (K{sub 0}) at temperatures 1123 K, 1173 K and 1223 K was 179.4 cm{sup 2}s{sup -1}. (orig.)

  6. Investigation into Composites Property Effect on the Forming Limits of Multi-Layer Hybrid Sheets Using Hydroforming Technology

    Science.gov (United States)

    Liu, Shichen; Lang, Lihui; Guan, Shiwei; Alexandrov, Seigei; Zeng, Yipan

    2018-04-01

    Fiber-metal laminates (FMLs) such as Kevlar reinforced aluminum laminate (ARALL), Carbon reinforced aluminum laminate (CARALL), and Glass reinforced aluminum laminate (GLARE) offer great potential for weight reduction applications in automobile and aerospace construction. In order to investigate the feasibility for utilizing such materials in the form of laminates, sheet hydroforming technology are studied under the condition of uniform blank holder force for three-layered aluminum and aluminum-composite laminates using orthogonal carbon and Kevlar as well as glass fiber in the middle. The experimental results validate the finite element results and they exhibited that the forming limit of glass fiber in the middle is the highest among the studied materials, while carbon fiber material performs the worst. Furthermore, the crack modes are different for the three kinds of fiber materials investigated in the research. This study provides fundamental guidance for the selection of multi-layer sheet materials in the future manufacturing field.

  7. HIV-1 transmission between MSM and heterosexuals, and increasing proportions of circulating recombinant forms in the Nordic Countries

    Science.gov (United States)

    Esbjörnsson, Joakim; Mild, Mattias; Audelin, Anne; Fonager, Jannik; Skar, Helena; Bruun Jørgensen, Louise; Liitsola, Kirsi; Björkman, Per; Bratt, Göran; Gisslén, Magnus; Sönnerborg, Anders; Nielsen, Claus; Medstrand, Patrik; Albert, Jan

    2016-01-01

    Increased knowledge about HIV-1 transmission dynamics in different transmission groups and geographical regions is fundamental for assessing and designing prevention efforts against HIV-1 spread. Since the first reported cases of HIV infection during the early 1980s, the HIV-1 epidemic in the Nordic countries has been dominated by HIV-1 subtype B and MSM transmission. HIV-1 pol sequences and clinical data of 51 per cent of all newly diagnosed HIV-1 infections in Sweden, Denmark, and Finland in the period 2000–2012 (N = 3,802) were analysed together with a large reference sequence dataset (N = 4,537) by trend analysis and phylogenetics. Analysis of the eight dominating subtypes and CRFs in the Nordic countries (A, B, C, D, G, CRF01_AE, CRF02_AG, and CRF06_cpx) showed that the subtype B proportion decreased while the CRF proportion increased over the study period. A majority (57 per cent) of the Nordic sequences formed transmission clusters, with evidence of mixing both geographically and between transmission groups. Detailed analyses showed multiple occasions of transmissions from MSM to heterosexuals and that active transmission clusters more often involved single than multiple Nordic countries. The strongest geographical link was between Denmark and Sweden. Finally, Denmark had a larger proportion of heterosexual domestic spread of HIV-1 subtype B (75 per cent) compared with Sweden (49 per cent) and Finland (57 per cent). We describe different HIV-1 transmission patterns between countries and transmission groups in a large geographical region. Our results may have implications for public health interventions in targeting HIV-1 transmission networks and identifying where to introduce such interventions. PMID:27774303

  8. Airborne observations of newly formed boundary layer aerosol particles under cloudy conditions

    Directory of Open Access Journals (Sweden)

    B. Altstädter

    2018-06-01

    Full Text Available This study describes the appearance of ultrafine boundary layer aerosol particles under classical non-favourable conditions at the research site of TROPOS (Leibniz Institute for Tropospheric Research. Airborne measurements of meteorological and aerosol properties of the atmospheric boundary layer (ABL were repeatedly performed with the unmanned aerial system ALADINA (Application of Light-weight Aircraft for Detecting IN-situ Aerosol during three seasons between October 2013 and July 2015. More than 100 measurement flights were conducted on 23 different days with a total flight duration of 53 h. In 26 % of the cases, maxima of ultrafine particles were observed close to the inversion layer at altitudes between 400 and 600 m and the particles were rapidly mixed vertically and mainly transported downwards during short time intervals of cloud gaps. This study focuses on two measurement days affected by low-level stratocumulus clouds, but different wind directions (NE, SW and minimal concentrations (< 4.6 µg m−3 of SO2, as a common indicator for precursor gases at ground. Taken from vertical profiles, the onset of clouds led to a non-linearity of humidity that resulted in an increased turbulence at the local-scale and caused fast nucleation e.g., but in relation to rapid dilution of surrounding air, seen in sporadic clusters of ground data, so that ultrafine particles disappeared in the verticality. The typical banana shape of new particle formation (NPF and growth was not seen at ground and thus these days might not have been classified as NPF event days by pure surface studies.

  9. Contribution of electron microscopy to the study of alteration layers formed on the surface of glasses

    International Nuclear Information System (INIS)

    Crovisier, J.L.; Eberhart, J.P.

    1985-01-01

    In order to understand the whole process of glass corrosion in aqueous solutions, the analysis of the reagent must be completed by a study of the actual alteration layers on the glass surface. Transmission electron microscopy on ultramicrotomic thin sections turns out to be a most suitable tool to achieve this. It enables to supplement the conventional methods of surface investigation, such as A.E.S., ESCA, IRRS, SIMS. Two examples are given. The first deals with a (SiO 2 -CaO-Na 2 O-P 2 O 5 )- glass leached in a buffer solution of tris-hydromethyl-aminomethane at 40 0 C. The major feature is ion exchange within a residual porous glass, followed by the precipitation of hydroxyapatite. In the second example, a basaltic glass is altered in sea-water at 50 0 C. The glass constituents are dissolved simultaneously and the alteration layer is a precipitate of crystalline and amorphous phases which have reached their saturation level [fr

  10. Ge clusters and wetting layers forming from granular films on the Si(001) surface

    International Nuclear Information System (INIS)

    Storozhevykh, M S; Arapkina, L V; Yuryev, V A

    2016-01-01

    The report studies the transformation of a Ge granular film deposited on the Si(001) surface at room temperature into a Ge/Si(001) heterostructure as a result of rapid heating and annealing at 600 °C. As a result of the short-term annealing at 600 °C in conditions of a closed system, the Ge granular film transforms into a usual wetting layer and Ge clusters with multimodal size distribution and Ge oval drops having the highest number density. After the long-term thermal treatment of the Ge film at the same temperature, Ge drops disappear; the large clusters increase their sizes at the expense of the smaller ones. The total density of Ge clusters on the surface drastically decreases. The wetting layer mixed c(4 x 2) + p(2 x 2) reconstruction transforms into a single c(4 x 2) one which is likely to be thermodynamically favoured. Pyramids or domes are not observed on the surface after any annealing. (paper)

  11. Novel Bioactive Titanate Layers Formed on Ti Metal and Its Alloys by Chemical Treatments

    Directory of Open Access Journals (Sweden)

    Tadashi Kokubo

    2009-12-01

    Full Text Available Sodium titanate formed on Ti metal by NaOH and heat treatments induces apatite formation on its surface in a body environment and bonds to living bone. These treatments have been applied to porous Ti metal in artificial hip joints, and have been used clinically in Japan since 2007. Calcium titanate formed on Ti-15Zr-4Nb-4Ta alloy by NaOH, CaCl2, heat, and water treatments induces apatite formation on its surface in a body environment. Titanium oxide formed on porous Ti metal by NaOH, HCl, and heat treatments exhibits osteoinductivity as well as osteoconductivity. This is now under clinical tests for application to a spinal fusion device.

  12. Zn Thin Film Deposition for Fe Layer Shielding Use the Sputtering Technique on Cylindrical Form

    International Nuclear Information System (INIS)

    Yunanto; Tjipto Sujitno, BA; Suprapto; Simbolon, Sahat

    2002-01-01

    Deposition of thin film on Fe substrate use sputtering technique on cylindrical form was carried out. The purpose of this research is to protect Fe due to the corrosion with Zn thin film. Sputtering method was proposed to protect a component of complex form. Substrate has functioned as anode, meanwhile target in cylindrical form as a cathode. Argon ion from anode bombard Zn with enough energy for releasing Zn. Zn atom would scatter and some of then was focused on the anode. For testing Zn atom on Fe by using XRF and corrosion rate with potentiostat. It was found that corrosion rate was decreased from 0.051 mpy to 0.031 mpy on 0.63 % of Fe substrate. (author)

  13. Diffusive boundary layers, photosynthesis, and respiration of the colony-forming plankton algae, Phaeocystis sp

    DEFF Research Database (Denmark)

    Ploug, Helle; Stolte, W.; Epping, E.H.G.

    1999-01-01

    H increased up to 0.4 units when measured in light at saturating intensities (>90 mu mol photons m(-2) s(-1)). The respiration in the dark was low, resulting in a 6% lowering in oxygen concentration and 0.04 units lowering in pH inside colonies, compared to the bulk water phase. Such colonies were net...... heterotrophic communities at light intensities up to 10 mu mol photons m(-2) s(-1). A week later, colonies were net heterotrophic at light intensities up to 80 mu mol photons m(-2) s(-1). The effective diffusion coefficient for oxygen in the gelatinous colonies was not significantly different from that in sea......Diffusive boundary layers, photosynthesis, and respiration in Phaeocystis colonies were studied by the use of microelectrodes for oxygen and pH during a bloom in the Barents Sea, 1993, and in the Marsdiep, Dutch North Sea, 1994. The oxygen microenvironment of a Phaeocystis colony with a mean...

  14. Characterization of Nitride Layers Formed by Nitrogen Ion Implantation into Surface Region of Iron

    International Nuclear Information System (INIS)

    Sudjatmoko; Subki, M. Iyos R.

    2000-01-01

    Ion implantation is a convenient means of modifying the physical and chemical properties of the near-surface region of materials. The nitrogen implantation into pure iron has been performed at room temperature with ion dose of 1.310 17 to 1.310 18 ions/cm 2 and ion energy of 20 to 100 keV. The optimum dose of nitrogen ions implanted into pure iron was around 2.2310 17 ions/cm 2 in order to get the maximum wear resistant. SEM micrographs and EDX show that the nitride layers were found on the surface of substrate. The nitrogen concentration profile was measured using EDX in combination with spot technique, and it can be shown that the depth profile of nitrogen implanted into substrate was nearly Gaussian. (author)

  15. Layers of Experience: Forms of Representation in a Waldorf School Classroom.

    Science.gov (United States)

    Nicholson, David W.

    2000-01-01

    Examines why a sixth-grade teacher in a Waldorf classroom selected the particular forms of representation for the lessons in a thematic unit. States that the teacher represented the lessons in ways that would bring about experiences, feelings, and imagination (such as story telling, visual arts, and singing.) (CMK)

  16. Calcium impurity as a source of non-radiative recombination in (In,Ga)N layers grown by molecular beam epitaxy

    KAUST Repository

    Young, E. C.; Grandjean, N.; Mates, T. E.; Speck, J. S.

    2016-01-01

    Ca as an unintentional impurity has been investigated in III-nitride layers grown by molecular beam epitaxy (MBE). It is found that Ca originates from the substrate surface, even if careful cleaning and rinsing procedures are applied. The initial Ca surface coverage is ∼1012 cm−2, which is consistent with previous reports on GaAs and silicon wafers. At the onset of growth, the Ca species segregates at the growth front while incorporating at low levels. The incorporation rate is strongly temperature dependent. It is about 0.03% at 820 °C and increases by two orders of magnitude when the temperature is reduced to 600 °C, which is the typical growth temperature for InGaN alloy. Consequently, [Ca] is as high as 1018 cm−3 in InGaN/GaN quantum well structures. Such a huge concentration might be detrimental for the efficiency of light emitting diodes (LEDs) if one considers that Ca is potentially a source of Shockley-Read-Hall (SRH) defects. We thus developed a specific growth strategy to reduce [Ca] in the MBE grown LEDs, which consisted of burying Ca in a low temperature InGaN/GaN superlattice (SL) before the growth of the active region. Finally, two LED samples with and without an SL were fabricated. An increase in the output power by one order of magnitude was achieved when Ca was reduced in the LED active region, providing evidence for the role of Ca in the SRH recombination.

  17. Calcium impurity as a source of non-radiative recombination in (In,Ga)N layers grown by molecular beam epitaxy

    KAUST Repository

    Young, E. C.

    2016-11-23

    Ca as an unintentional impurity has been investigated in III-nitride layers grown by molecular beam epitaxy (MBE). It is found that Ca originates from the substrate surface, even if careful cleaning and rinsing procedures are applied. The initial Ca surface coverage is ∼1012 cm−2, which is consistent with previous reports on GaAs and silicon wafers. At the onset of growth, the Ca species segregates at the growth front while incorporating at low levels. The incorporation rate is strongly temperature dependent. It is about 0.03% at 820 °C and increases by two orders of magnitude when the temperature is reduced to 600 °C, which is the typical growth temperature for InGaN alloy. Consequently, [Ca] is as high as 1018 cm−3 in InGaN/GaN quantum well structures. Such a huge concentration might be detrimental for the efficiency of light emitting diodes (LEDs) if one considers that Ca is potentially a source of Shockley-Read-Hall (SRH) defects. We thus developed a specific growth strategy to reduce [Ca] in the MBE grown LEDs, which consisted of burying Ca in a low temperature InGaN/GaN superlattice (SL) before the growth of the active region. Finally, two LED samples with and without an SL were fabricated. An increase in the output power by one order of magnitude was achieved when Ca was reduced in the LED active region, providing evidence for the role of Ca in the SRH recombination.

  18. Identification of Novel Recombinant Forms of Hepatitis B Virus Generated from Genotypes Ae and G in HIV-1-Positive Japanese Men Who Have Sex with Men.

    Science.gov (United States)

    Kojima, Yoko; Kawahata, Takuya; Mori, Haruyo; Furubayashi, Keiichi; Taniguchi, Yasushi; Itoda, Ichiro; Komano, Jun

    2015-07-01

    The rare hepatitis B virus (HBV) genotype G (HBV/G) coinfects HIV-1-positive individuals along with HBV/A and generates recombinants. However, the circulation of HBV A/G recombinants remains poorly understood. This molecular epidemiologic study examined HBV A/G recombinants in Japanese HIV-1-positive men who have sex with men (MSM). Initially, blood specimens submitted for confirmatory tests of HIV infection in Osaka and Tokyo, Japan, from 2006 to 2013 were examined for HIV-1, and HIV-1-positive specimens were screened for HBV. Among 817 specimens from HIV-1-positive individuals, HBsAg was detected in 59 specimens; of these, HBV/Ae (alternatively A2), a subgenotype of HBV/A prevalent in Europe and North America, was identified in 70.2%, HBV/C in 17.5%, and HBV/G in 10.5%, and HBV/E in 1.8% according to the core gene sequence. The full-length genome analysis of HBV was performed on HBV/G-positive specimens because some HBV A/G recombinants were historically overlooked by genotyping based on a partial genome analysis. It revealed that five of the specimens contained novel Ae/G recombinants, the core gene of which had a high sequence similarity to HBV/G. Detailed analyses showed that novel recombinants were coinfected with HBV/Ae in a recombinant-dominant fashion. No major drug-resistant mutations were found in the newly identified HBV Ae/G recombinants. Some of the individuals asymptomatically coinfected with HIV/HBV suffered mild liver injury. This study demonstrated that novel Ae/G HBV recombinants were identified in Japanese HIV-1-positive MSM. The pathogenicity of novel HBV Ae/G recombinants should be examined in a future longitudinal study. Surveillance of such viruses in HIV-1-positive individuals should be emphasized.

  19. Chemical composition and electronic structure of the passive layer formed on stainless steels in a glucose-oxidase solution

    Energy Technology Data Exchange (ETDEWEB)

    Marconnet, C. [Laboratoire de Genie des Procedes et des Materiaux, Ecole Centrale Paris, Grande Voie des Vignes, 92290 CHATENAY-MALABRY (France)], E-mail: cyril.marconnet@yahoo.fr; Wouters, Y. [Science et Ingenierie des Materiaux et Procedes, Institut National Polytechnique de Grenoble, F-38402 Saint-Martin d' Heres Cedex (France); Miserque, F. [Laboratoire de Reactivite des Surfaces et des Interfaces, CEA Saclay, Bat. 391, 91191 GIF-SUR-YVETTE (France); Dagbert, C. [Laboratoire de Genie des Procedes et des Materiaux, Ecole Centrale Paris, Grande Voie des Vignes, 92290 CHATENAY-MALABRY (France)], E-mail: catherine.dagbert@ecp.fr; Petit, J.-P. [Laboratoire d' Electrochimie et de Physico-chimie des Materiaux et des Interfaces, INPG, F-38402 Saint-Martin d' Heres Cedex (France); Galerie, A. [Science et Ingenierie des Materiaux et Procedes, Institut National Polytechnique de Grenoble, F-38402 Saint-Martin d' Heres Cedex (France); Feron, D. [Service de Corrosion et du Comportement des Materiaux dans leur Environnement, CEA Saclay, Bat. 458, 91191 GIF-SUR-YVETTE (France)

    2008-12-01

    This article deals with the interaction between the passive layer formed on UNS S30403 and S31254 stainless steels and an enzymatic solution containing glucose oxidase (GOx) and its substrate D-glucose. This enzymatic solution is often used to reproduce in laboratory the ennoblement occuring in non-sterile aerated aqueous environments because of the biofilm settlement on the surface of the metallic material. GOx catalyses the oxidation of D-glucose to gluconic acid by reducing oxygen to hydrogen peroxide and produces an organic acid. Thanks to photocurrent measurements, XPS analysis and Mott-Schottky diagrams, it is here shown that such an environment generates modifications in the chemical composition and electronic structure of the passive layer: it induces a relative enrichment of the n-type semi-conducting phase containing chromium (chromine Cr{sub 2}O{sub 3}) and an increase of the donors density in the space charge region.

  20. Chemical composition and electronic structure of the passive layer formed on stainless steels in a glucose-oxidase solution

    International Nuclear Information System (INIS)

    Marconnet, C.; Wouters, Y.; Miserque, F.; Dagbert, C.; Petit, J.-P.; Galerie, A.; Feron, D.

    2008-01-01

    This article deals with the interaction between the passive layer formed on UNS S30403 and S31254 stainless steels and an enzymatic solution containing glucose oxidase (GOx) and its substrate D-glucose. This enzymatic solution is often used to reproduce in laboratory the ennoblement occuring in non-sterile aerated aqueous environments because of the biofilm settlement on the surface of the metallic material. GOx catalyses the oxidation of D-glucose to gluconic acid by reducing oxygen to hydrogen peroxide and produces an organic acid. Thanks to photocurrent measurements, XPS analysis and Mott-Schottky diagrams, it is here shown that such an environment generates modifications in the chemical composition and electronic structure of the passive layer: it induces a relative enrichment of the n-type semi-conducting phase containing chromium (chromine Cr 2 O 3 ) and an increase of the donors density in the space charge region

  1. Optimization of a multi-gene HIV-1 recombinant subtype CRF02AG DNA vaccine for expression of multiple immunogenic forms

    International Nuclear Information System (INIS)

    Ellenberger, Dennis; Li Bin; Smith, James; Yi Hong; Folks, Thomas; Robinson, Harriet; Butera, Salvatore

    2004-01-01

    We developed an AIDS vaccine for Western and West-Central Africa based on a DNA plasmid vector expressing HIV-1 recombinant subtype CRF02 A G gag, pol, and env genes. To optimize the production of noninfectious HIV-like particles (VLPs) and potentially improve the effectiveness of the vaccine, we generated four potential vaccine constructs: the parental (IC2) and three modifications (IC25, IC48, and IC90) containing mutations within the HIV protease. While the parental construct IC2 expressed aggregates of Gag proteins, the IC25 construct resulted in the production of immature VLPs (the core comprises unprocessed Pr 55Gag ). The remaining two constructs (IC48 and IC90) produced mature VLPs (the core comprises processed capsid p24) in addition to immature VLPs and aggregates of Gag proteins. VLPs incorporated significant levels of mature gp120 envelope glycoprotein. Importantly, the mature VLPs were fusion competent and entered coreceptor-specific target cells. The production of multiple antigenic forms, including fusion-competent VLPs, by candidate DNA vaccine constructs may provide immunologic advantages for induction of protective cellular and humoral responses against HIV-1 proteins

  2. PrP aggregation can be seeded by pre-formed recombinant PrP amyloid fibrils without the replication of infectious prions.

    Science.gov (United States)

    Barron, Rona M; King, Declan; Jeffrey, Martin; McGovern, Gillian; Agarwal, Sonya; Gill, Andrew C; Piccardo, Pedro

    2016-10-01

    Mammalian prions are unusual infectious agents, as they are thought to consist solely of aggregates of misfolded prion protein (PrP). Generation of synthetic prions, composed of recombinant PrP (recPrP) refolded into fibrils, has been utilised to address whether PrP aggregates are, indeed, infectious prions. In several reports, neurological disease similar to transmissible spongiform encephalopathy (TSE) has been described following inoculation and passage of various forms of fibrils in transgenic mice and hamsters. However, in studies described here, we show that inoculation of recPrP fibrils does not cause TSE disease, but, instead, seeds the formation of PrP amyloid plaques in PrP-P101L knock-in transgenic mice (101LL). Importantly, both WT-recPrP fibrils and 101L-recPrP fibrils can seed plaque formation, indicating that the fibrillar conformation, and not the primary sequence of PrP in the inoculum, is important in initiating seeding. No replication of infectious prions or TSE disease was observed following both primary inoculation and subsequent subpassage. These data, therefore, argue against recPrP fibrils being infectious prions and, instead, indicate that these pre-formed seeds are acting to accelerate the formation of PrP amyloid plaques in 101LL Tg mice. In addition, these data reproduce a phenotype which was previously observed in 101LL mice following inoculation with brain extract containing in vivo-generated PrP amyloid fibrils, which has not been shown for other synthetic prion models. These data are reminiscent of the "prion-like" spread of aggregated forms of the beta-amyloid peptide (Aβ), α-synuclein and tau observed following inoculation of transgenic mice with pre-formed seeds of each misfolded protein. Hence, even when the protein is PrP, misfolding and aggregation do not reproduce the full clinicopathological phenotype of disease. The initiation and spread of protein aggregation in transgenic mouse lines following inoculation with pre-formed

  3. Neodymium conversion layers formed on zinc powder for improving electrochemical properties of zinc electrodes

    International Nuclear Information System (INIS)

    Zhu Liqun; Zhang Hui; Li Weiping; Liu Huicong

    2008-01-01

    Zinc powder, as active material of secondary alkaline zinc electrode, can greatly limit the performance of zinc electrode due to corrosion and dendritic growth of zinc resulting in great capacity-loss and short cycle life of the electrode. This work is devoted to modification study of zinc powder with neodymium conversion films coated directly onto it using ultrasonic immersion method for properties improvement of zinc electrodes. Scanning electron microscopy and other characterization techniques are applied to prove that neodymium conversion layers are distributing on the surface of modified zinc powder. The electrochemical performance of zinc electrodes made of such modified zinc powder is investigated through potentiodynamic polarization, potentiostatic polarization and cyclic voltammetry. The neodymium conversion films are found to have a significant effect on inhibition corrosion capability of zinc electrode in a beneficial way. It is also confirmed that the neodymium conversion coatings can obviously suppress dendritic growth of zinc electrode, which is attributed to the amelioration of deposition state of zinc. Moreover, the results of cyclic voltammetry reveal that surface modification of zinc powder enhances the cycle performance of the electrode mainly because the neodymium conversion films decrease the amounts of ZnO or Zn(OH) 2 dissolved in the electrolyte

  4. Radiographic and Histologic Evaluation of a Bone Void that Formed After Recombinant Human Bone Morphogenetic Protein-2-Mediated Sinus Graft Augmentation: A Case Report.

    Science.gov (United States)

    Kang, Hyun-Joo; Jun, Choong-Man; Yun, Jeong-Ho

    2016-01-01

    In the present case report, the authors describe radiographic and histologic observations of a bone void that formed after a sinus augmentation using a graft material that contained recombinant human bone morphogenetic protein-2 (rhBMP-2) and discuss clinical and histologic implications of their findings. Sinus augmentation was performed using a graft material comprising 1 g of hydroxyapatite/β-tricalcium phosphate, which contained 1 mg of rhBMP-2. Radiographic evaluation was conducted with panoramic radiographs and computed tomography images of the augmented maxillary sinus, which were analyzed using a three-dimensional image-reconstruction program. Histologic evaluation was also performed on a biopsy specimen obtained 6 months after the sinus augmentation. The total augmented volume increased from 1,582.2 mm(3) immediately after the sinus augmentation to 3,344.9 mm3 at 6 months after the augmentation because of the formation of a bone void. Twenty-six months after the sinus augmentation, the bone void remained but had reduced in volume, with the total augmented volume reduced to 2,551.7 mm(3). Histologically, new bone was observed to be in contact with the grafted particles, and a fatty marrow-like tissue was present in the area of the bone void. This case report shows that the bone void that had formed after sinus augmentation resolved over time and seemed to be partially replaced with new bone. Furthermore, none of the implants failed, and clinical adverse events were not observed during the follow-up period.

  5. Rust Layer Formed on Low Carbon Weathering Steels with Different Mn, Ni Contents in Environment Containing Chloride Ions

    Directory of Open Access Journals (Sweden)

    Gui-qin FU

    2016-11-01

    Full Text Available The rusting evolution of low carbon weathering steels with different Mn, Ni contents under a simulated environment containing chloride ions has been investigated to clarify the correlation between Mn, Ni and the rust formed on steels. The results show that Mn contents have little impact on corrosion kinetics of experimental steels. Content increase of Ni both enhances the anti-corrosion performance of steel substrate and the rust. Increasing Ni content is beneficial to forming compact rust. Semi-quantitative XRD phase analysis shows that the quantity ratio of α/γ*(α-FeOOH/(γ-FeOOH+Fe3O4 decreases as Mn content increases but it increases as Ni content increases. Ni enhances rust layer stability but Mn content exceeding 1.06 wt.% is disadvantageous for rust layer stability. The content increase of Mn does not significantly alter the parameters of the polarization curve. However, as Ni contents increases, Ecorr has shifted to the positive along with decreased icorr values indicating smaller corrosion rate especially as Ni content increases from 0.42 wt.% to 1.50 wt.%.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12844

  6. Effect of lead on Inconel 600 and Incoloy 800 oxide layers formed in simulated steam generator secondary environments

    International Nuclear Information System (INIS)

    Garcia-Mazario, M.; Lancha, A.M.; Hernandez, M.; Maffiotte, C.

    1996-01-01

    The existence of lead in steam generators, detected during the analysis of deposits in the damaged areas of tubing, supports the hypothesis that lead may contribute to the cracking problems experienced in steam generator tubes. In addition, the harmful effect of lead on Inconel 600 is known not only through laboratory tests but also as a result of operating experience. Operating experience of Incoloy 800 is, however, much more limited and there are very few laboratory studies in this area. Taking into account that thin films formed on metals reflect the interaction between such metals and the aqueous environment and also that incoloy 800 is considered to be a suitable material for new steam generators as a substitute for Inconel 600, attempts to determine the effect of lead on corrosion films are considered useful with a view to better understanding the stress-corrosion-cracking behaviour of these materials. For these reasons the objective of this paper is to gain some insights into the effect of lead on the oxide layers forming on Inconel 600 and Incoloy 800 tested in the laboratory in various aggressive lead-containing environments. Auger electron spectroscopy (AES) and electron spectroscopy for chemical analysis (ESCA) have been used to study the composition of these oxide layers. (orig.)

  7. Identification of a novel gene cluster in the upstream region of the S-layer gene sbpA involved in cell wall metabolism of Lysinibacillus sphaericus CCM 2177 and characterization of the recombinantly produced autolysin and pyruvyl transferase.

    Science.gov (United States)

    Pleschberger, Magdalena; Hildner, Florian; Rünzler, Dominik; Gelbmann, Nicola; Mayer, Harald F; Sleytr, Uwe B; Egelseer, Eva M

    2013-05-01

    The S-layer protein SbpA of Lysinibacillus sphaericus CCM 2177 assembles into a square (p4) lattice structure and recognizes a pyruvylated secondary cell wall polymer (SCWP) as the proper anchoring structure to the rigid cell wall layer. Sequencing of 8,004 bp in the 5'-upstream region of the S-layer gene sbpA led to five ORFs-encoding proteins involved in cell wall metabolism. After cloning and heterologous expression of ORF1 and ORF5 in Escherichia coli, the recombinant autolysin rAbpA and the recombinant pyruvyl transferase rCsaB were isolated, purified, and correct folding was confirmed by circular dichroism. Although rAbpA encoded by ORF1 showed amidase activity, it could attack whole cells of Ly. sphaericus CCM 2177 only after complete extraction of the S-layer lattice. Despite the presence of three S-layer-homology motifs on the N-terminal part, rAbpA did not show detectable affinity to peptidoglycan-containing sacculi, nor to isolated SCWP. As the molecular mass of the autolysin lies above the molecular exclusion limit of the S-layer, AbpA is obviously trapped within the rigid cell wall layer by the isoporous protein lattice. Immunogold-labeling of ultrathin-sectioned whole cells of Ly. sphaericus CCM 2177 with a polyclonal rabbit antiserum raised against rCsaB encoded by ORF5, and cell fractionation experiments demonstrated that the pyruvyl transferase was located in the cytoplasm, but not associated with cell envelope components including the plasma membrane. In enzymatic assays, rCsaB clearly showed pyruvyl transferase activity. By using RT-PCR, specific transcripts for each ORF could be detected. Cotranscription could be confirmed for ORF2 and ORF3.

  8. Efficient Planar Structured Perovskite Solar Cells with Enhanced Open-Circuit Voltage and Suppressed Charge Recombination Based on a Slow Grown Perovskite Layer from Lead Acetate Precursor.

    Science.gov (United States)

    Li, Cong; Guo, Qiang; Wang, Zhibin; Bai, Yiming; Liu, Lin; Wang, Fuzhi; Zhou, Erjun; Hayat, Tasawar; Alsaedi, Ahmed; Tan, Zhan'ao

    2017-12-06

    For planar structured organic-inorganic hybrid perovskite solar cells (PerSCs) with the poly(3,4-ethylenedioxythiophene:polystyrene sulfonate) (PEDOT:PSS) hole transport layer, the open-circuit voltage (V oc ) of the device is limited to be about 1.0 V, resulting in inferior performance in comparison with TiO 2 -based planar counterparts. Therefore, increasing V oc of the PEDOT:PSS-based planar device is an important way to enhance the efficiency of the PerSCs. Herein, we demonstrate a novel approach for perovskite film formation and the film is formed by slow growth from lead acetate precursor via a one-step spin-coating process without the thermal annealing (TA) process. Because the perovskite layer grows slowly and naturally, high-quality perovskite film can be achieved with larger crystalline particles, less defects, and smoother surface morphology. Ultraviolet absorption, X-ray diffraction, scanning electron microscopy, steady-state fluorescence spectroscopy (photoluminescence), and time-resolved fluorescence spectroscopy are used to clarify the crystallinity, morphology, and internal defects of perovskite thin films. The power conversion efficiency of p-i-n PerSCs based on slow-grown film (16.33%) shows greatly enhanced performance compared to that of the control device based on traditional thermally annealed perovskite film (14.33%). Furthermore, the V oc of the slow-growing device reaches 1.12 V, which is 0.1 V higher than that of the TA device. These findings indicate that slow growth of the perovskite layer from lead acetate precursor is a promising approach to achieve high-quality perovskite film for high-performance PerSCs.

  9. Protection conferred by recombinant turkey herpesvirus avian influenza (rHVT-H5) vaccine in the rearing period in two commercial layer chicken breeds in Egypt.

    Science.gov (United States)

    Kilany, Walid; Dauphin, Gwenaelle; Selim, Abdullah; Tripodi, Astrid; Samy, Mohamed; Sobhy, Heba; VonDobschuetz, Sophie; Safwat, Marwa; Saad, Mona; Erfan, Ahmed; Hassan, Mohamed; Lubroth, Juan; Jobre, Yilma

    2014-01-01

    The effectiveness of recombinant turkey herpesvirus avian influenza (A/swan/Hungary/4999/2006(H5N1)) clade 2.2 virus (rHVT-H5) vaccine was evaluated in two layer chicken breeds (White Bovans [WB] and Brown Shaver [BS]). One dose of rHVT-H5 vaccine was administered at day 1 and birds were monitored serologically (haemagglutination inhibition test) and virologically for 19 weeks. Maternally-derived antibody and post-vaccination H5 antibody titres were measured using the Chinese (A/Goose/Guangdong/1/96(H5N1)) HA and the Egyptian (A/chicken/Egypt/128s/2012(H5N1)) HA as antigens. The challenge was conducted at 19 weeks of age and on six experimental groups: Groups I (WB) and II (BS), both vaccinated and challenged; Groups III (WB) and IV (BS), both vaccinated but not challenged; Groups V and VI, unvaccinated specific pathogen free chickens, serving respectively as positive and negative controls. The challenge virus was the clade 2.2.1 highly pathogenic avian influenza H5N1 A/chicken/Egypt/128s/2012 at a dose of 10(6) median embryo infective dose. For both breeds, complete maternally-derived antibody waning occurred at the age of 4 weeks. The immune response to rHVT-H5 vaccination was detected from the sixth week. The seroconversion rates for both breeds reached 85.7 to 100% in the eighth week of age. Protection levels of 73.3%, 60% and 0% were respectively recorded in Groups I, II and V. No mortalities occurred in the unchallenged groups. Group I showed superior results for all measured post-challenge parameters. In conclusion, a single rHVT-H5 hatchery vaccination conferred a high level of protection for a relatively extended period. This vaccine could be an important tool for future A/H5N1 prevention/control in endemic countries. Further studies on persistence of immunity beyond 19 weeks, need for booster with inactivated vaccines, breed susceptibility and vaccinal response, and transmissibility are recommended.

  10. The Bipolar Filaments Formed by Herpes Simplex Virus Type 1 SSB/Recombination Protein (ICP8) Suggest a Mechanism for DNA Annealing

    Energy Technology Data Exchange (ETDEWEB)

    Makhov, A.M.; Simon, M.; Sen, A.; Yu, X.; Griffith, J. D.; Egelman, E. H.

    2009-02-20

    Herpes simplex virus type 1 encodes a multifunctional protein, ICP8, which serves both as a single-strand binding protein and as a recombinase, catalyzing reactions involved in replication and recombination of the viral genome. In the presence of divalent ions and at low temperature, previous electron microscopic studies showed that ICP8 will form long left-handed helical filaments. Here, electron microscopic image reconstruction reveals that the filaments are bipolar, with an asymmetric unit containing two subunits of ICP8 that constitute a symmetrical dimer. This organization of the filament has been confirmed using scanning transmission electron microscopy. The pitch of the filaments is {approx} 250 {angstrom}, with {approx} 6.2 dimers per turn. Docking of a crystal structure of ICP8 into the reconstructed filament shows that the C-terminal domain of ICP8, attached to the body of the subunit by a flexible linker containing {approx} 10 residues, is packed into a pocket in the body of a neighboring subunit in the crystal in a similar manner as in the filament. However, the interactions between the large N-terminal domains are quite different in the filament from that observed in the crystal. A previously proposed model for ICP8 binding single-stranded DNA (ssDNA), based upon the crystal structure, leads to a model for a continuous strand of ssDNA near the filament axis. The bipolar nature of the ICP8 filaments means that a second strand of ssDNA would be running through this filament in the opposite orientation, and this provides a potential mechanism for how ICP8 anneals complementary ssDNA into double-stranded DNA, where each strand runs in opposite directions.

  11. Risk group characteristics and viral transmission clusters in South-East Asian patients infected with HIV-1 circulating recombinant form (CRF)01_AE and subtype B

    Science.gov (United States)

    Oyomopito, Rebecca A; Chen, Yen-Ju; Sungkanuparph, Somnuek; Kantor, Rami; Merati, Tuti; Yam, Wing-Cheong; Sirisanthana, Thira; Li, Patrick CK; Kantipong, Pacharee; Phanuphak, Praphan; Lee, Chris KC; Kamarulzaman, Adeeba; Ditangco, Rossana; Huang, Szu-Wei; Sohn, Annette H; Law, Matthew; Chen, Yi Ming A

    2016-01-01

    HIV-1 epidemics in Asian countries are driven by varying exposures. The epidemiology of the regional pandemic has been changing with the spread of HIV-1 to lower-risk populations through sexual transmission. Common HIV-1 genotypes include subtype B and circulating recombinant form (CRF)01_AE. Our objective was to use HIV-1 genotypic data to better quantify local epidemics. TASER-M is a multi-centre prospective cohort of HIV-infected patients. Associations between HIV-exposure, patient gender, country of sample origin and HIV-1 genotype were evaluated by multivariate logistic regression. Phylogenetic methods were used on genotypic data to investigate transmission relationships. A total of 1086 patients from Thailand, Hong Kong, Malaysia and the Philippines were included in analyses. Proportions of males within countries varied (Thailand: 55.6%, Hong Kong: 86.1%, Malaysia: 81.4%, Philippines: 93.8%; p Malaysia: 47.8%, Philippines: 25.0%; p <0.001). After adjustment, we found increased subtype B infection among men-who-have-sex with-men, relative to heterosexual-reported exposures (OR = 2.4, p <0.001). We further describe four transmission clusters of 8–15 treatment naive, predominantly symptomatic patients (two each for subtype B and CRF01_AE). Risk-group sub-populations differed with respect to the infecting HIV-1 genotype. Homosexual exposure patients had a higher odds of being infected with subtype B. Where HIV-1 genotypes circulate within countries or patient risk-groups, local monitoring of genotype-specific transmissions may play a role in focussing public health prevention strategies. Phylogenetic evaluations provide complementary information for surveillance and monitoring of viruses with high mutation rates such as HIV-1 and Ebola. PMID:26362956

  12. Genetic Recombination

    Science.gov (United States)

    Whitehouse, H. L. K.

    1973-01-01

    Discusses the mechanisms of genetic recombination with particular emphasis on the study of the fungus Sordaria brevicollis. The study of recombination is facilitated by the use of mutants of this fungus in which the color of the ascospores is affected. (JR)

  13. Electron transfer through solid-electrolyte-interphase layers formed on Si anodes of Li-ion batteries

    International Nuclear Information System (INIS)

    Benitez, L.; Cristancho, D.; Seminario, J.M.; Martinez de la Hoz, J.M.; Balbuena, P.B.

    2014-01-01

    Solid-electrolyte interphase (SEI) films are formed on the electrode surfaces due to aggregation of products of reduction or oxidation of the electrolyte. These films may grow to thicknesses in the order of 50-100 nm and contain a variety of organic and inorganic products but their structure is not well defined. Although in some cases the films exert a passivating role, this is not always the case, and these phenomena are particularly more complex on Silicon anodes due to swelling and cracking of the electrode during lithiation and delithiation. Since the driving force for SEI growth is electron transfer, it is important to understand how electron transfer may keep occurring through the heterogeneous film once the bare electron surface is covered. Here we introduce a novel approach for studying electron transfer through model films and show preliminary results for the analysis of electron transfer through model composite interfacial systems integrated by electrode/SEI layer/electrolyte. Ab initio molecular dynamics simulations are used to identify deposition of SEI components, and a density functional theory/Green's function approach is utilized for characterizing electron transfer. Three degrees of lithiation are modeled for the electrodes, the SEI film is composed by LiF or Li 2 O, and the ethylene carbonate reduction is studied. An applied potential is used as driving force for the leakage current, which is evaluated as a function of the applied potential. Comparative analyses are done for LiF and Li 2 O model SEI layers

  14. Separation of metals in the form of ion associates by the method of thin-layer chromatography

    International Nuclear Information System (INIS)

    Shapovalova, E.N.; Timerbaev, A.R.; Bol'shova, T.A.; Mel'nik, S.V.; Kordejro, E.

    1990-01-01

    Behaviour of pyridylazo resorcinates of certain metals (Ga, In, Fe, Co) in the form of ionic pairs with tri-n-octylamine (TOA) under conditions of thin-layer chromatography (TLC) has been studied. For all eluents investigated Ga and In complexes possess the highest mobility. Selectivity of ionic associate separation decreases with an increase in mobile phase polarity. Mixtures with 10-15 % content of isopropanol in eluating solution are the optimal ones. Separation of Ga and In from Fe 3+ and Co takes place with separation criterion 3.1 and 4.1 respectively. An attempt to separate ionic associates of In and Ga failed owing to similar stability of their pyridylazoresorcinates. Solution of the problem of In and Ga determination in the presence of iron can contribute to concrete application of the method

  15. Chemical properties and GMR improvement of specular spin valves with nano-oxide layers, formed in ambient mixed gases

    International Nuclear Information System (INIS)

    Quang, H D; Hien, N T; Oh, S K; Sinh, N H; Yu, S C

    2004-01-01

    Specular spin valves (SVs) containing nano-oxide layers (NOLs) structured as substrate/seed/AF/P 1 /NOL/P 2 /Cu/F/NOL, have been fabricated. The NOLs were formed by natural oxidation in different ambient atmospheres of pure oxygen, oxygen/nitrogen and oxygen/argon gas mixtures. The fabrication conditions were optimized to enhance the magnetoresistance (MR) ratio, to suppress the interlayer coupling fields (H f ) between the free and pinned layers, to suppress the high interface density of the NOL, to ease the control of the NOL thickness and to form a smooth NOL/P 2 interface for promoting specular electron scattering. The characteristics of our specular SVs are the MR ratio of 14.1%, the exchange bias field of 44-45 mT, and H f weaker than 1.0 mT. The optimal conditions for oxidation time, total oxidation pressure and the annealing temperature were found to be 300 s, 0.14 Pa (oxygen/argon = 80/20) and 250 deg. C, respectively. Also, the origin of thermal stability of MMn-based (M = Fe, Pt, Ir, etc) specular SVs has been explained in detail by chemical properties of NOL using secondary-ion mass spectroscopy and x-ray photoelectron spectroscopy depth profile analyses. Thermal stability turns out to be caused by a decrease in MR ratios at high temperatures (>250 deg. C), which is a serious problem for device applications using the SV structure as a high density read head device

  16. In vitro and in vivo characterization of DNA delivery using recombinant Lactococcus lactis expressing a mutated form of L. monocytogenes Internalin A

    NARCIS (Netherlands)

    Azevedo, de M.; Karczewski, J.; Lefevre, F.; Azevedo, V.; Miyoshi, A.; Wells, J.; Langella, P.; Chatel, J.M.

    2012-01-01

    Background The use of food-grade Lactic Acid Bacteria (LAB) as DNA delivery vehicles represents an attractive strategy to deliver DNA vaccines at the mucosal surfaces as they are generally regarded as safe (GRAS). We previously showed that either native Lactococcus lactis (LL) or recombinant

  17. LAYER STRUCTURES FORMED BY SILICA NANOPARTICLES AND CELLULOSE NANOFIBRILS WITH CATIONIC POLYACRYLAMIDE (C-PAM ON CELLULOSE SURFACE AND THEIR INFLUENCE ON INTERACTIONS

    Directory of Open Access Journals (Sweden)

    Jani Salmi

    2009-05-01

    Full Text Available A quartz crystal microbalance with dissipation monitoring (QCM-D was used to study the adsorption of the layer formed by silica nanoparticles (SNP and cellulose nanofibrils (NFC together with cationic polyacrylamide (C-PAM on cellulose surface, accompanied by use of atomic force microscope (AFM to study the interactions between cellulose surfaces. The purpose was to understand the multilayer build-up compared to complex structure adsorption. The layer thickness and consequently also the repulsion between surfaces increased with each addition step during layer formation in the SNP-C-PAM systems, whereas the second addition of C-PAM decreased the repulsion in the case of NFC-C-PAM multilayer formation. An exceptionally high repulsion between surfaces was observed when nanofibrillar cellulose was added. This together with the extremely high dissipation values recorded with QCM-D indicated that nanofibrillar cellulose formed a loose and thick layer containing a lot of water. The multilayer systems formed fully and uniformly covered the surfaces. Silica nanoparticles were able to penetrate inside the loose C-PAM structure due to their small size. In contrast, NFC formed individual layers between C-PAM layers. The complex of C-PAM and SNP formed only a partly covered surface, leading to long-ranged pull-off force. This might explain the good flocculation properties reported for polyelectrolyte-nanoparticle systems.

  18. Difference between Cr and Ni K-edge XANES spectra of rust layers formed on Fe-based binary alloys exposed to Cl-rich environment

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmospheres. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements. Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys. Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganeite or magnetite. As a consequence, Ni negligibly interacts with Cl - ions in the rust layer. (author)

  19. Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

    DEFF Research Database (Denmark)

    Huang, Li‐Zhi; Ayala‐Luis, Karina B.; Fang, Liping

    2013-01-01

    hydroxide planar layer were preserved during the oxidation, as shown by FTIR spectroscopy. The high positive charge in the hydroxide layer produced by the oxidation of iron(II) to iron(III) is partially compensated by the deprotonation of hydroxy groups, as shown by X‐ray photoelectron spectroscopy...... between the alkyl chains of the intercalated dodecanoate anions play a crucial role in stabilizing the structure and hindering the collapse of the iron(II)–iron(III) (hydr)oxide structure during oxidation. This is the first report describing the formation of a stable planar layered octahedral iron......(III) (hydr)oxide. oxGRC12 shows promise as a sorbent and host for hydrophobic reagents, and as a possible source of single planar layers of iron(III) (hydr)oxide....

  20. Analysis of chemical bond states and electrical properties of stacked AlON/HfO{sub 2} gate oxides formed by using a layer-by-layer technique

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Wonjoon; Lee, Jonghyun; Yang, Jungyup; Kim, Chaeok; Hong, Jinpyo; Nahm, Tschanguh; Byun, Byungsub; Kim, Moseok [Hanyang University, Seoul (Korea, Republic of)

    2006-06-15

    Stacked AlON/HfO{sub 2} thin films for gate oxides in metal-oxide-semiconductor devices are successfully prepared on Si substrates by utilizing a layer-by-layer technique integrated with an off-axis RF remote plasma sputtering process at room temperature. This off-axis structure is designed to improve the uniformity and the quality of gate oxide films. Also, a layer-by-layer technique is used to control the interface layer between the gate oxide and the Si substrate. The electrical properties of our stacked films are characterized by using capacitance versus voltage and leakage current versus voltage measurements. The stacked AlON/HfO{sub 2} gate oxide exhibits a low leakage current of about 10{sup -6} A/cm{sup 2} and a high dielectric constant value of 14.26 by effectively suppressing the interface layer between gate oxide and Si substrate. In addition, the chemical bond states and the optimum thickness of each AlON and HfO{sub 2} thin film are analyzed using X-ray photoemission spectroscopy and transmission electron microscopy measurement.

  1. Enhanced Charge Collection with Passivation Layers in Perovskite Solar Cells.

    Science.gov (United States)

    Lee, Yong Hui; Luo, Jingshan; Son, Min-Kyu; Gao, Peng; Cho, Kyung Taek; Seo, Jiyoun; Zakeeruddin, Shaik M; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

    2016-05-01

    The Al2 O3 passivation layer is beneficial for mesoporous TiO2 -based perovskite solar cells when it is deposited selectively on the compact TiO2 surface. Such a passivation layer suppressing surface recombination can be formed by thermal decomposition of the perovskite layer during post-annealing. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Lipid peroxidation and total cholesterol in HAART-naïve patients infected with circulating recombinant forms of human immunodeficiency virus type-1 in Cameroon.

    Directory of Open Access Journals (Sweden)

    Georges Teto

    different subtypes obtained after sequencing were CRF02_AG (43.3%, CRF01_AE (20%, A1 (23.3%, H (6.7%, and G (6.7%. None of the HIV-1 subtypes significantly influenced the levels of the biochemical parameters, but by grouping them as pure subtypes and circulating recombinant forms (CRFs, the CRF significantly influenced TC levels. TC was significantly lower in patients infected with CRF (0.87±0.27 g/l compared to patients infected with pure HIV-1 subtypes (1.32±0.68 g/l (p<0.017. MDA levels were also significantly higher in patients infected with HIV-1CRF01_AE (0.50±0.10 µM, compared to patients infected with CRF02_AG (0. 38±0. 08 µM (p<0.018.These results show that HIV infection in Cameroon is associated with significant decrease in TAA, LDLC, HDLC and TC, and increased MDA concentration and LPI indices which seem to be linked to the severity of HIV infection as assessed by CD4 cell count. The data suggests increased oxidative stress and lipid peroxidation in HIV-infected patients in Cameroon, and an influence of CRFs on TC and MDA levels.

  3. Rapid visible color change and physical swelling during water exposure in triethanolamine-metalcone films formed by molecular layer deposition

    International Nuclear Information System (INIS)

    Lemaire, Paul C.; Oldham, Christopher J.; Parsons, Gregory N.

    2016-01-01

    Molecular layer deposition (MLD) of “metalcones,” including alucone, zincone, titanicone, and others, involves self-limiting half-reactions between organic and organometallic (or metal-halide) reactants. Studies have typically focused on metal precursors reacting with ethylene glycol or glycerol to form the films' polymeric O-M-O-(CH x ) y -O-M-O repeat units. The authors report new MLD materials that incorporate tertiary amine groups into the organic linkage. Specifically, reacting triethanolamine (TEA) with either trimethylaluminum or titanium tetrachloride produces TEA-alucone (Al-TEA) and TEA-titanicone (Ti-TEA), respectively, and the amine group leads to unique physical and optical properties. Fourier-transform infrared (FTIR) analysis confirms that the films have prominent C-H, C-N, and M-O-C peaks, consistent with the expected bond structure. When exposed to vapors, including water, alcohol, or ammonia, the Ti-TEA films changed their visible color within minutes and increased physical thickness by >35%. The Al-TEA showed significantly less response. X-ray photoelectron spectroscopy and FTIR suggest that HCl generated during MLD coordinates to the amine forming a quaternary ammonium salt that readily binds adsorbates via hydrogen bonding. The visible color change is reversible, and ellipsometry confirms that the color change results from vapor absorption. The unique absorptive and color-changing properties of the TEA-metalcone films point to new possible applications for MLD materials in filtration, chemical absorption, and multifunctional chemical separations/sensing device systems

  4. Rapid visible color change and physical swelling during water exposure in triethanolamine-metalcone films formed by molecular layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, Paul C.; Oldham, Christopher J.; Parsons, Gregory N., E-mail: gnp@ncsu.edu [Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2016-01-15

    Molecular layer deposition (MLD) of “metalcones,” including alucone, zincone, titanicone, and others, involves self-limiting half-reactions between organic and organometallic (or metal-halide) reactants. Studies have typically focused on metal precursors reacting with ethylene glycol or glycerol to form the films' polymeric O-M-O-(CH{sub x}){sub y}-O-M-O repeat units. The authors report new MLD materials that incorporate tertiary amine groups into the organic linkage. Specifically, reacting triethanolamine (TEA) with either trimethylaluminum or titanium tetrachloride produces TEA-alucone (Al-TEA) and TEA-titanicone (Ti-TEA), respectively, and the amine group leads to unique physical and optical properties. Fourier-transform infrared (FTIR) analysis confirms that the films have prominent C-H, C-N, and M-O-C peaks, consistent with the expected bond structure. When exposed to vapors, including water, alcohol, or ammonia, the Ti-TEA films changed their visible color within minutes and increased physical thickness by >35%. The Al-TEA showed significantly less response. X-ray photoelectron spectroscopy and FTIR suggest that HCl generated during MLD coordinates to the amine forming a quaternary ammonium salt that readily binds adsorbates via hydrogen bonding. The visible color change is reversible, and ellipsometry confirms that the color change results from vapor absorption. The unique absorptive and color-changing properties of the TEA-metalcone films point to new possible applications for MLD materials in filtration, chemical absorption, and multifunctional chemical separations/sensing device systems.

  5. Analysis of nanopore arrangement of porous alumina layers formed by anodizing in oxalic acid at relatively high temperatures

    Science.gov (United States)

    Zaraska, Leszek; Stępniowski, Wojciech J.; Jaskuła, Marian; Sulka, Grzegorz D.

    2014-06-01

    Anodic aluminum oxide (AAO) layers were formed by a simple two-step anodization in 0.3 M oxalic acid at relatively high temperatures (20-30 °C) and various anodizing potentials (30-65 V). The effect of anodizing conditions on structural features of as-obtained oxides was carefully investigated. A linear and exponential relationships between cell diameter, pore density and anodizing potential were confirmed, respectively. On the other hand, no effect of temperature and duration of anodization on pore spacing and pore density was found. Detailed quantitative and qualitative analyses of hexagonal arrangement of nanopore arrays were performed for all studied samples. The nanopore arrangement was evaluated using various methods based on the fast Fourier transform (FFT) images, Delaunay triangulations (defect maps), pair distribution functions (PDF), and angular distribution functions (ADF). It was found that for short anodizations performed at relatively high temperatures, the optimal anodizing potential that results in formation of nanostructures with the highest degree of pore order is 45 V. No direct effect of temperature and time of anodization on the nanopore arrangement was observed.

  6. The structure of carbon nanotubes formed of graphene layers L4-8, L5-7, L3-12, L4-6-12

    Science.gov (United States)

    Shapovalova, K. E.; Belenkov, E. A.

    2017-11-01

    We geometrically calculate the optimized structure of nanotubes based on the graphene layers, using the method of molecular mechanics MM+. It was found that only the nanotubes, based on the graphene layers L4-8, L5-7, L3-12, L4-6-12, have a cylindrical form. Calculations of the sublimation energy, carried out using the semi-empirical quantum-mechanic method PM3, show that energy increases with the increase of nanotube diameters.

  7. Changes in the physical properties of the dynamic layer and its correlation with permeate quality in a self-forming dynamic membrane bioreactor.

    Science.gov (United States)

    Guan, Dao; Dai, Ji; Watanabe, Yoshimasa; Chen, Guanghao

    2018-09-01

    The self-forming dynamic membrane bioreactor (SFDMBR) is a biological wastewater treatment technology based on the conventional membrane bioreactor (MBR) with membrane material modification to a large pore size (30-100 μm). This modification requires a dynamic layer formed by activated sludge to provide effective filtration function for high-quality permeate production. The properties of the dynamic layer are therefore important for permeate quality in SFDMBRs. The interaction between the structure of the dynamic layer and the performance of SFDMBRs is little known but understandably complex. To elucidate the interaction, a lab-scale SFDMBR system coupled with a nylon woven mesh as the supporting material was operated. After development of a mature dynamic layer, excellent solid-liquid separation was achieved, as evidenced by a low permeate turbidity of less than 2 NTU. The permeate turbidity stayed below this level for nearly 80 days. In the fouling phase, the dynamic layer was compressed with an increase in the trans-membrane pressure and the quality of the permeate kept deteriorating until the turbidity exceeded 10 NTU. The investigation revealed that the majority of permeate particles were dissociated from the dynamic layer on the back surface of the supporting material, which is caused by the compression, breakdown, and dissociation of the dynamic layer. This phenomenon was observed directly in experiment instead of model prediction or conjecture for the first time. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Characteristic electron energy loss spectra in SiC buried layers formed by C+ implantation into crystalline silicon

    International Nuclear Information System (INIS)

    Yan Hui; Chen Guanghua; Kwok, R.W.M.

    1998-01-01

    SiC buried layers were synthesized by a metal vapor vacuum arc ion source, with C + ions implanted into crystalline Si substrates. According to X-ray photoelectron spectroscopy, the characteristic electron energy loss spectra of the SiC buried layers were studied. It was found that the characteristic electron energy loss spectra depend on the profiles of the carbon content, and correlate well with the order of the buried layers

  9. Effects of Cr-N-ZrO 2 seed layer formed on glass substrates for longitudinal recording media

    Science.gov (United States)

    Suzuki, Hiroyuki; Djayaprawira, David D.; Takahashi, Yoshio; Ishikawa, Akira; Ono, Toshinori; Yahisa, Yotsuo

    1999-03-01

    Effects of Cr-N-ZrO 2 seed layer deposited on glass substrates before the deposition of C/Co-Cr-Pt/Cr-Ti layers for longitudinal recording media have been investigated. The product of v and Is, the activation volume and the saturation magnetization per unit volume, media noise Nd and S0/ Nd, which is the half value of peak-to-peak output voltage of an isolated pulse over Nd at 11.8 kFC/mm, are evaluated. We find that vIs is decreased by adding N and ZrO 2 to Cr seed layer. Nd is reduced as vIs decreases by adding nitrogen to the Cr seed layer. This is mainly due to the decreased grain sizes of both Cr-Ti underlayer and Co-Cr-Pt magnetic layer. The Nd is further reduced by the addition of ZrO 2 to the Cr-N seed layer. Highest S0/ Nd is achieved for the media with Cr-N-ZrO 2 seed layer. On the other hand, the media with Cr-ZrO 2 seed layer deposited without nitrogen show the higher Nd. Therefore the decrease of the grain size by addition of nitrogen into Ar is essential to reduce Nd, and the ZrO 2 addition to the Cr-N seed layer seems to enhance the effect of grain size reduction by nitrogen addition.

  10. Internal deformation in layered Zechstein-III K-Mg salts. Structures formed by complex deformation and high contrasts in viscosity observed in drill cores.

    Science.gov (United States)

    Raith, Alexander; Urai, Janos L.

    2016-04-01

    During the evaporation of a massive salt body, alternations of interrupted and full evaporation sequences can form a complex layering of different lithologies. Viscosity contrasts of up to five orders of magnitude between these different lithologies are possible in this environment. During the late stage of an evaporation cycle potassium and magnesium (K-Mg) salts are precipitated. These K-Mg salts are of economic interest but also a known drilling hazard due to their very low viscosity. How up to 200m thick layers of these evaporites affect salt deformation at different scales is not well known. A better understanding of salt tectonics with extreme mechanical stratification is needed for better exploration and production of potassium-magnesium salts and to predict the internal structure of potential nuclear waste repositories in salt. To gain a better understanding of the internal deformation of these layers we analyzed K-Mg salt rich drill cores out of the Zechstein III-1b subunit from the Veendam Pillow 10 km southeast of Groningen, near the city Veendam in the NE Netherlands. The study area has a complex geological history with multiple tectonic phases of extension and compression forming internal deformation in the pillow but also conserving most of the original layering. Beside halite the most common minerals in the ZIII-1b are carnallite, kieserite, anhydrite and bischofite alternating in thin layers of simple composition. Seismic interpretation revealed that the internal structure of the Veendam Pillow shows areas, in which the K-Mg salt rich ZIII 1b layer is much thicker than elsewhere, as a result of salt deformation. The internal structure of the ZIII-1b on the other hand, remains unknown. The core analysis shows a strong strain concentration in the weaker Bischofite (MgCl2*6H20) and Carnallite (KMgCl3*6H20) rich layers producing tectonic breccias and highly strained layers completely overprinting the original layering. Layers formed by alternating beds

  11. Spectrum Recombination.

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    1984-01-01

    Describes several methods of executing lecture demonstrations involving the recombination of the spectrum. Groups the techniques into two general classes: bringing selected portions of the spectrum together using lenses or mirrors and blurring the colors by rapid movement or foreshortening. (JM)

  12. Ultrathin highly uniform Ni(Al) germanosilicide layer with modulated B8 type Ni5(SiGe)3 phase formed on strained Si1−xGex layers

    International Nuclear Information System (INIS)

    Liu, Linjie; Xu, Dawei; Jin, Lei; Knoll, Lars; Wirths, Stephan; Nichau, Alexander; Buca, Dan; Mussler, Gregor; Holländer, Bernhard; Zhao, Qing-Tai; Mantl, Siegfried; Feng Di, Zeng; Zhang, Miao

    2013-01-01

    We present a method to form ultrathin highly uniform Ni(Al) germanosilicide layers on compressively strained Si 1−x Ge x substrates and their structural characteristics. The uniform Ni(Al) germanosilicide film is formed with Ni/Al alloy at an optimized temperature of 400 °C with an optimized Al atomic content of 20 at. %. We find only two kinds of grains in the layer. Both grains show orthogonal relationship with modified B8 type phase. The growth plane is identified to be (10-10)-type plane. After germanosilicidation the strain in the rest Si 1−x Ge x layer is conserved, which provides a great advantage for device application

  13. Fabrication of Hadfield-Cored Multi-layer Steel Sheet by Roll-Bonding with 1.8-GPa-Strength-Grade Hot-Press-Forming Steel

    Science.gov (United States)

    Chin, Kwang-Geun; Kang, Chung-Yun; Park, Jaeyeong; Lee, Sunghak

    2018-05-01

    An austenitic Hadfield steel was roll-bonded with a 1.8-GPa-strength-grade martensitic hot-press-forming (HPF) steel to fabricate a multi-layer steel (MLS) sheet. Near the Hadfield/HPF interface, the carburized and decarburized layers were formed by the carbon diffusion from the Hadfield (1.2%C) to HPF (0.35%C) layers, and could be regarded as kinds of very thin multi-layers of 35 μm in thickness. The tensile test and fractographic data indicated that the MLS sheet was fractured abruptly within the elastic range by the intergranular fracture occurred in the carburized layer. This was because C was mainly segregated at prior austenite grain boundaries in the carburized layer, which weakened grain boundaries to induce the intergranular fracture. In order to solve the intergranular facture problem, the MLS sheet was tempered at 200 °C. The stress-strain curve of the tempered MLS sheet lay between those of the HPF and Hadfield sheets, and a rule of mixtures was roughly satisfied. Tensile properties of the MLS sheet were dramatically improved after the tempering, and the intergranular fracture was erased completely. In particular, the yield strength up to 1073 MPa along with the high strain hardening and excellent ductility of 32.4% were outstanding because the yield strength over 1 GPa was hardly achieved in conventional austenitic steels.

  14. Charge recombination reduction in dye-sensitized solar cells by means of an electron beam-deposited TiO2 buffer layer between conductive glass and photoelectrode

    International Nuclear Information System (INIS)

    Manca, Michele; Malara, Francesco; Martiradonna, Luigi; De Marco, Luisa; Giannuzzi, Roberto; Cingolani, Roberto; Gigli, Giuseppe

    2010-01-01

    A thin anatase titanium dioxide compact film was deposited by electron beam evaporation as buffer layer between the conductive transparent electrode and the porous TiO 2 -based photoelectrode in dye-sensitized solar cells. The effect of such a buffer layer on the back transfer reaction of electrons to tri-iodide ions in liquid electrolyte-based cells has been studied by means of both electrochemical impedance spectroscopy and open circuit photovoltage decay analysis. The influence of the thickness has been also investigated and an increment in overall quantum conversion efficiency η as high as + 31% with respect to the standard cell - fabricated onto an uncoated conductive glass - has been revealed in the case of a 120 nm thick buffer layer.

  15. Impedance Characterization of the Capacitive field-Effect pH-Sensor Based on a thin-Layer Hafnium Oxide Formed by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Michael LEE

    2014-05-01

    Full Text Available As a sensing element, silicon dioxide (SiO2 has been applied within ion-sensitive field effect transistors (ISFET. However, a requirement of increasing pH-sensitivity and stability has observed an increased number of insulating materials that obtain high-k gate being applied as FETs. The increased high-k gate reduces the required metal oxide layer and, thus, the fabrication of thin hafnium oxide (HfO2 layers by atomic layer deposition (ALD has grown with interest in recent years. This metal oxide presents advantageous characteristics that can be beneficial for the advancements within miniaturization of complementary metal oxide semiconductor (CMOS technology. In this article, we describe a process for fabrication of HfO2 based on ALD by applying water (H2O as the oxygen precursor. As a first, electrochemical impedance spectroscopy (EIS measurements were performed with varying pH (2-10 to demonstrate the sensitivity of HfO2 as a potential pH sensing material. The Nyquist plot demonstrates a high clear shift of the polarization resistance (Rp between pH 6-10 (R2 = 0.9986, Y = 3,054X + 12,100. At acidic conditions (between pH 2-10, the Rp change was small due to the unmodified oxide gate (R2 = 0.9655, Y = 2,104X + 4,250. These preliminary results demonstrate the HfO2 substrate functioned within basic to neutral conditions and establishes a great potential for applying HfO2 as a dielectric material for future pH measuring FET sensors.

  16. Regularities in forming hardened layer during electric spark alloying on the mechanized plant EhFI-66

    International Nuclear Information System (INIS)

    Verkhoturov, A.D.; Zajtsev, E.A.

    1975-01-01

    The regularities in erosion and formation of a hardened layer during electric spark alloying by a mechanized installation EFI-66-type have been studied. The heat resisting metals: Ti,Zr,V,Nb,Ta,Cr,Mo,W have been used as material for alloying electrodes. The effect of the thermophysical constants, as well as of the time of treatment and the material nature have been investigated. No direct dependence of erosion on the thermophysical constants was found. The erosion resistance of material, when treated by a mechanized installation, depends on its plasticity. Tantalum appeared to be more erosion-resistant, its cold-embrittlement temperature being the least. The dependence of the erosion on the alloying time is of a linear character. Depending on the nature of material are the most erosive vanadium and chromium, tantalum is the least erosive. The metallographic analysis has shown, that in the electric spark alloying by means of the mechanized installation the hardened layer could be subdivided into a ''white'' layer of high hardness and a layer of transformed structure. The ''white'' layer thickness is practically the same for each of the metals. The largest summary thickness of the layer is observed when alloying with the metals Ti, Zr, Nb, Ta

  17. Use of recombinant alpha-2b-interferon in combination with antioxidants in the form of rectal suppositories (viferon) in children with chronic hepatitides B and C.

    Science.gov (United States)

    Uchaikin, V; Cherednichenko, T; Malinovskaya, V; Orlova, T; Kovalev, O; Kharlamova, F; Chaplygina, G; Konev, V; Voronina, F; Delenian, N

    2000-04-01

    A new antiviral and immunomodulating preparation Viferon, produced as rectal suppositories containing recombinant alpha-2b-interferon (IFN) and antioxidants, was used in complex therapy of viral chronic hepatitides B and C (ChHB and ChHC) in children. Results of our investigation showed a high efficiency of Viferon. Viferon was found to suppress replication of hepatotropic viruses and to decrease activity of the pathologic process in the liver of children with ChHB and ChHC. After a Viferon treatment with daily doses of (1-2) x 10(6) IU of IFN (3.0 x 10(6) IU/m2) primary remission was registered in 78% of patients with ChHB and in 44% of patients with ChHC, while lasting remission was found in 82% of ChHB and in 33% of ChHC patients. Thus, a more marked effect was observed with ChHB, in which 3.0 x 10(6) IU/m2 was the optimal daily dose for children. Increasing the dose to 5.0 x 10(6) IU/m2 did not result in rise of the percentage of the remissions. Side effects, which are characteristic for injection of IFN preparations, were never found even after a longterm treatment. Absence of induction of neutralizing antibodies was observed after administration of alpha-2b-IFN, an integral part of Viferon. In pediatrics, the method of rectal administration has advantages over parenteral delivery due to its convenience, non-traumatic character and possibility of use for prolonged periods.

  18. HIV-1 subtypes B and C unique recombinant forms (URFs and transmitted drug resistance identified in the Western Cape Province, South Africa.

    Directory of Open Access Journals (Sweden)

    Graeme Brendon Jacobs

    Full Text Available South Africa has the largest worldwide HIV/AIDS population with 5.6 million people infected and at least 2 million people on antiretroviral therapy. The majority of these infections are caused by HIV-1 subtype C. Using genotyping methods we characterized HIV-1 subtypes of the gag p24 and pol PR and RT fragments, from a cohort of female participants in the Western Cape Province, South Africa. These participants were recruited as part of a study to assess the combined brain and behavioural effects of HIV and early childhood trauma. The partial HIV-1 gag and pol fragments of 84 participants were amplified by PCR and sequenced. Different online tools and manual phylogenetic analysis were used for HIV-1 subtyping. Online tools included: REGA HIV Subtyping tool version 3; Recombinant Identification Program (RIP; Context-based Modeling for Expeditious Typing (COMET; jumping profile Hidden Markov Models (jpHMM webserver; and subtype classification using evolutionary algorithms (SCUEAL. HIV-1 subtype C predominates within the cohort with a prevalence of 93.8%. We also show, for the first time, the presence of circulating BC strains in at least 4.6% of our study cohort. In addition, we detected transmitted resistance associated mutations in 4.6% of analysed sequences. With tourism and migration rates to South Africa currently very high, we are detecting more and more HIV-1 URFs within our study populations. It is still unclear what role these unique strains will play in terms of long term antiretroviral treatment and what challenges they will pose to vaccine development. Nevertheless, it remains vitally important to monitor the HIV-1 diversity in South Africa and worldwide as the face of the epidemic is continually changing.

  19. Spatial variation of the number of graphene layers formed on the scratched 6H-SiC(0 0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Osaklung, J. [School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Euaruksakul, C. [Synchrotron Light Research Institute, Nakhon Ratchasima 30000 (Thailand); Thailand Center of Excellence in Physics, CHE, Bangkok 10400 (Thailand); Meevasana, W., E-mail: worawat@g.sut.ac.th [School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Synchrotron Light Research Institute, Nakhon Ratchasima 30000 (Thailand); Thailand Center of Excellence in Physics, CHE, Bangkok 10400 (Thailand); Songsiriritthigul, P. [School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Synchrotron Light Research Institute, Nakhon Ratchasima 30000 (Thailand); Thailand Center of Excellence in Physics, CHE, Bangkok 10400 (Thailand)

    2012-03-01

    The unique properties of graphene can vary greatly depending on the number of graphene layers; therefore, spatial control of graphene thickness is desired to fully exploit these properties in promising new devices. Using low energy electron microscopy (LEEM), we investigate how scratches on the surface of 6H-SiC(0 0 0 1) affect the epitaxial growth of graphene. Oscillations in the LEEM-image intensity as a function of electron energy (I-V LEEM analysis) show that the number of graphene layers clearly differs between regions of scratched and smooth substrate. The extent of the thicker graphene layers formed above scratches is found to be significantly larger than the width of the scratch itself. This finding can be implemented as an additional technique for spatially modulating graphene thickness.

  20. Morphology and growing of nanometric multilayered films formed by alternated layers of poly(3,4-ethylenedioxythiophene) and poly(N-methylpyrrole)

    Energy Technology Data Exchange (ETDEWEB)

    Aradilla, David [Departament d' Enginyeria Quimica, E. T. S. d' Enginyers Industrials, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain); Estrany, Francesc, E-mail: francesc.estrany@upc.ed [Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain); Unitat de Quimica Industrial, Escola Universitaria d' Enginyeria Tecnica Industrial de Barcelona, Universitat Politecnica de Catalunya, Comte d' Urgell 187, 08036 Barcelona (Spain); Armelin, Elaine [Departament d' Enginyeria Quimica, E. T. S. d' Enginyers Industrials, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain); Aleman, Carlos, E-mail: carlos.aleman@upc.ed [Departament d' Enginyeria Quimica, E. T. S. d' Enginyers Industrials, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain)

    2010-05-31

    Multilayered nanometric films formed by alternated layers of conducting poly(3,4-ethylenedioxythiophene) and poly(N-methylpyrrole) doped with perchlorate anions (ml-PEDOT/PNMPy) have been prepared using a layer-by-layer electrodeposition technique combined with a very small polymerization time. The mechanisms of formation and growth of the resulting multilayered systems have been investigated using Atomic Force Microscopy (AFM), and compared with those obtained for the corresponding homopolymers, which were prepared using identical experimental conditions. Furthermore, the local conductivity, electroactivity and electrostability have been also examined. Analyses of the morphology, topography and roughness of the surfaces indicate that the formation and growth of the multilayered films strongly depend on the number of layers as well as on the chemical nature of the conducting polymer. Interestingly, AFM reflects that the formation and growth of the ml-PEDOT/PNMPy films are significantly different from those of PEDOT and PNMPy homopolymers. The electrical and electrochemical properties of the systems under study are fully consistent with the proposed mechanisms. Results evidenced that multilayered systems formed by two conducting polymers are more advantageous from a technological point of view than the corresponding copolymers.

  1. Morphology and growing of nanometric multilayered films formed by alternated layers of poly(3,4-ethylenedioxythiophene) and poly(N-methylpyrrole)

    International Nuclear Information System (INIS)

    Aradilla, David; Estrany, Francesc; Armelin, Elaine; Aleman, Carlos

    2010-01-01

    Multilayered nanometric films formed by alternated layers of conducting poly(3,4-ethylenedioxythiophene) and poly(N-methylpyrrole) doped with perchlorate anions (ml-PEDOT/PNMPy) have been prepared using a layer-by-layer electrodeposition technique combined with a very small polymerization time. The mechanisms of formation and growth of the resulting multilayered systems have been investigated using Atomic Force Microscopy (AFM), and compared with those obtained for the corresponding homopolymers, which were prepared using identical experimental conditions. Furthermore, the local conductivity, electroactivity and electrostability have been also examined. Analyses of the morphology, topography and roughness of the surfaces indicate that the formation and growth of the multilayered films strongly depend on the number of layers as well as on the chemical nature of the conducting polymer. Interestingly, AFM reflects that the formation and growth of the ml-PEDOT/PNMPy films are significantly different from those of PEDOT and PNMPy homopolymers. The electrical and electrochemical properties of the systems under study are fully consistent with the proposed mechanisms. Results evidenced that multilayered systems formed by two conducting polymers are more advantageous from a technological point of view than the corresponding copolymers.

  2. Cross-Sectional Imaging of Boundary Lubrication Layer Formed by Fatty Acid by Means of Frequency-Modulation Atomic Force Microscopy.

    Science.gov (United States)

    Hirayama, Tomoko; Kawamura, Ryota; Fujino, Keita; Matsuoka, Takashi; Komiya, Hiroshi; Onishi, Hiroshi

    2017-10-10

    To observe in situ the adsorption of fatty acid onto metal surfaces, cross-sectional images of the adsorption layer were acquired by frequency-modulation atomic force microscopy (FM-AFM). Hexadecane and palmitic acid were used as the base oil and typical fatty acid, respectively. A Cu-coated silicon wafer was prepared as the target substrate. The solvation structure formed by hexadecane molecules at the interface between the Cu substrate and the hexadecane was observed, and the layer pitch was found to be about 0.6 nm, which corresponds to the height of hexadecane molecules. This demonstrates that hexadecane molecules physically adsorbed onto the surface due to van der Waals forces with lying orientation because hexadecane is a nonpolar hydrocarbon. When hexadecane with palmitic acid was put on the Cu substrate instead of pure hexadecane, an adsorption layer of palmitic acid was observed at the interface. The layer pitch was about 2.5-2.8 nm, which matches the chain length of palmitic acid molecules well. This indicates that the original adsorption layer was monolayer or single bilayer in the local area. In addition, a cross-sectional image captured 1 h after observation started to reveal that the adsorbed additive layer gradually grew up to be thicker than about 20 nm due to an external stimulus, such as cantilever oscillation. This is the first report of in situ observation of an adsorbed layer by FM-AFM in the tribology field and demonstrates that FM-AFM is useful for clarifying the actual boundary lubrication mechanism.

  3. Heterojunctions formed by annealing of GaSe and InSe layered crystals in zinc vapor

    Directory of Open Access Journals (Sweden)

    Kudrynskyi Z. R.

    2012-12-01

    Full Text Available The article presents a method of creating heterojunc¬tions based on semiconductors with different lattice types. Substrates manufactured from GaSe and InSe layered crystals were annealed in Zn vapor. This way, n-ZnSe–p-GaSe and n-ZnSe–p-InSe heterojunctions were obtained. The obtained heterojunctions are photo¬sensitive in near and infrared spectral regions. This method opens up greate possibilities of producing heterostructures with a desired sensitivity band.

  4. Light-emitting Si nanostructures formed by swift heavy ions in stoichiometric SiO2 layers

    Science.gov (United States)

    Kachurin, G. A.; Cherkova, S. G.; Marin, D. V.; Kesler, V. G.; Volodin, V. A.; Skuratov, V. A.

    2012-07-01

    Three hundred and twenty nanometer-thick SiO2 layers were thermally grown on the Si substrates. The layers were irradiated with 167 MeV Xe ions to the fluences ranging between 1012 cm-2 and 1014 cm-2, or with 700 MeV Bi ions in the fluence range of 3 × 1012-1 × 1013 cm-2. After irradiation the yellow-orange photoluminescence (PL) band appeared and grew with the ion fluences. In parallel optical absorption in the region of 950-1150 cm-1, Raman scattering and X-ray photoelectron spectroscopy evidenced a decrease in the number of Si-O bonds and an increase in the number of Si-coordinated atoms. The results obtained are interpreted as the formation of the light-emitting Si-enriched nanostructures inside the tracks of swift heavy ions through the disproportionation of SiO2. Ionization losses of the ions are regarded as responsible for the processes observed. Difference between the dependences of the PL intensity on the fluences of Xe and Bi ions are ascribed to their different stopping energy, therewith the diameters of the tracks of Xe and Bi ions were assessed as <3 nm and ˜10 nm, respectively. The observed shift of the PL bands, induced by Xe and Bi ions, agrees with the predictions of the quantum confinement theory.

  5. Light-emitting Si nanostructures formed by swift heavy ions in stoichiometric SiO{sub 2} layers

    Energy Technology Data Exchange (ETDEWEB)

    Kachurin, G.A., E-mail: kachurin@isp.nsc.ru [A.V. Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk (Russian Federation); Cherkova, S.G. [A.V. Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk (Russian Federation); Marin, D.V. [A.V. Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Kesler, V.G. [A.V. Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk (Russian Federation); Volodin, V.A. [A.V. Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Skuratov, V.A. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2012-07-01

    Three hundred and twenty nanometer-thick SiO{sub 2} layers were thermally grown on the Si substrates. The layers were irradiated with 167 MeV Xe ions to the fluences ranging between 10{sup 12} cm{sup -2} and 10{sup 14} cm{sup -2}, or with 700 MeV Bi ions in the fluence range of 3 Multiplication-Sign 10{sup 12}-1 Multiplication-Sign 10{sup 13} cm{sup -2}. After irradiation the yellow-orange photoluminescence (PL) band appeared and grew with the ion fluences. In parallel optical absorption in the region of 950-1150 cm{sup -1}, Raman scattering and X-ray photoelectron spectroscopy evidenced a decrease in the number of Si-O bonds and an increase in the number of Si-coordinated atoms. The results obtained are interpreted as the formation of the light-emitting Si-enriched nanostructures inside the tracks of swift heavy ions through the disproportionation of SiO{sub 2}. Ionization losses of the ions are regarded as responsible for the processes observed. Difference between the dependences of the PL intensity on the fluences of Xe and Bi ions are ascribed to their different stopping energy, therewith the diameters of the tracks of Xe and Bi ions were assessed as <3 nm and {approx}10 nm, respectively. The observed shift of the PL bands, induced by Xe and Bi ions, agrees with the predictions of the quantum confinement theory.

  6. Light-emitting Si nanostructures formed by swift heavy ions in stoichiometric SiO2 layers

    International Nuclear Information System (INIS)

    Kachurin, G.A.; Cherkova, S.G.; Marin, D.V.; Kesler, V.G.; Volodin, V.A.; Skuratov, V.A.

    2012-01-01

    Three hundred and twenty nanometer-thick SiO 2 layers were thermally grown on the Si substrates. The layers were irradiated with 167 MeV Xe ions to the fluences ranging between 10 12 cm −2 and 10 14 cm −2 , or with 700 MeV Bi ions in the fluence range of 3 × 10 12 –1 × 10 13 cm −2 . After irradiation the yellow–orange photoluminescence (PL) band appeared and grew with the ion fluences. In parallel optical absorption in the region of 950–1150 cm −1 , Raman scattering and X-ray photoelectron spectroscopy evidenced a decrease in the number of Si–O bonds and an increase in the number of Si-coordinated atoms. The results obtained are interpreted as the formation of the light-emitting Si-enriched nanostructures inside the tracks of swift heavy ions through the disproportionation of SiO 2 . Ionization losses of the ions are regarded as responsible for the processes observed. Difference between the dependences of the PL intensity on the fluences of Xe and Bi ions are ascribed to their different stopping energy, therewith the diameters of the tracks of Xe and Bi ions were assessed as <3 nm and ∼10 nm, respectively. The observed shift of the PL bands, induced by Xe and Bi ions, agrees with the predictions of the quantum confinement theory.

  7. Characterization of Ag-porous silicon nanostructured layer formed by an electrochemical etching of p-type silicon surface for bio-application

    Science.gov (United States)

    Naddaf, M.; Al-Mariri, A.; Haj-Mhmoud, N.

    2017-06-01

    Nanostructured layers composed of silver-porous silicon (Ag-PS) have been formed by an electrochemical etching of p-type (1 1 1) silicon substrate in a AgNO3:HF:C2H5OH solution at different etching times (10 min-30 min). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) results reveal that the produced layers consist of Ag dendrites and a silicon-rich porous structure. The nanostructuring nature of the layer has been confirmed by spatial micro-Raman scattering and x-ray diffraction techniques. The Ag dendrites exhibit a surface-enhanced Raman scattering (SERS) spectrum, while the porous structure shows a typical PS Raman spectrum. Upon increasing the etching time, the average size of silicon nanocrystallite in the PS network decreases, while the average size of Ag nanocrystals is slightly affected. In addition, the immobilization of prokaryote Salmonella typhimurium DNA via physical adsorption onto the Ag-PS layer has been performed to demonstrate its efficiency as a platform for detection of biological molecules using SERS.

  8. Method and apparatus for forming high-critical-temperature superconducting layers on flat and/or elongated substrates

    Science.gov (United States)

    Ciszek, Theodore F.

    1994-01-01

    An elongated, flexible superconductive wire or strip is fabricated by pulling it through and out of a melt of metal oxide material at a rate conducive to forming a crystalline coating of superconductive metal oxide material on an elongated, flexible substrate wire or strip. A coating of crystalline superconductive material, such as Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8, is annealed to effect conductive contact between adjacent crystalline structures in the coating material, which is then cooled to room temperature. The container for the melt can accommodate continuous passage of the substrate through the melt. Also, a second pass-through container can be used to simultaneously anneal and overcoat the superconductive coating with a hot metallic material, such as silver or silver alloy. A hollow, elongated tube casting method of forming an elongated, flexible superconductive wire includes drawing the melt by differential pressure into a heated tubular substrate.

  9. A closed-form analytical model for predicting 3D boundary layer displacement thickness for the validation of viscous flow solvers

    Science.gov (United States)

    Kumar, V. R. Sanal; Sankar, Vigneshwaran; Chandrasekaran, Nichith; Saravanan, Vignesh; Natarajan, Vishnu; Padmanabhan, Sathyan; Sukumaran, Ajith; Mani, Sivabalan; Rameshkumar, Tharikaa; Nagaraju Doddi, Hema Sai; Vysaprasad, Krithika; Sharan, Sharad; Murugesh, Pavithra; Shankar, S. Ganesh; Nejaamtheen, Mohammed Niyasdeen; Baskaran, Roshan Vignesh; Rahman Mohamed Rafic, Sulthan Ariff; Harisrinivasan, Ukeshkumar; Srinivasan, Vivek

    2018-02-01

    A closed-form analytical model is developed for estimating the 3D boundary-layer-displacement thickness of an internal flow system at the Sanal flow choking condition for adiabatic flows obeying the physics of compressible viscous fluids. At this unique condition the boundary-layer blockage induced fluid-throat choking and the adiabatic wall-friction persuaded flow choking occur at a single sonic-fluid-throat location. The beauty and novelty of this model is that without missing the flow physics we could predict the exact boundary-layer blockage of both 2D and 3D cases at the sonic-fluid-throat from the known values of the inlet Mach number, the adiabatic index of the gas and the inlet port diameter of the internal flow system. We found that the 3D blockage factor is 47.33 % lower than the 2D blockage factor with air as the working fluid. We concluded that the exact prediction of the boundary-layer-displacement thickness at the sonic-fluid-throat provides a means to correctly pinpoint the causes of errors of the viscous flow solvers. The methodology presented herein with state-of-the-art will play pivotal roles in future physical and biological sciences for a credible verification, calibration and validation of various viscous flow solvers for high-fidelity 2D/3D numerical simulations of real-world flows. Furthermore, our closed-form analytical model will be useful for the solid and hybrid rocket designers for the grain-port-geometry optimization of new generation single-stage-to-orbit dual-thrust-motors with the highest promising propellant loading density within the given envelope without manifestation of the Sanal flow choking leading to possible shock waves causing catastrophic failures.

  10. A closed-form analytical model for predicting 3D boundary layer displacement thickness for the validation of viscous flow solvers

    Directory of Open Access Journals (Sweden)

    V. R. Sanal Kumar

    2018-02-01

    Full Text Available A closed-form analytical model is developed for estimating the 3D boundary-layer-displacement thickness of an internal flow system at the Sanal flow choking condition for adiabatic flows obeying the physics of compressible viscous fluids. At this unique condition the boundary-layer blockage induced fluid-throat choking and the adiabatic wall-friction persuaded flow choking occur at a single sonic-fluid-throat location. The beauty and novelty of this model is that without missing the flow physics we could predict the exact boundary-layer blockage of both 2D and 3D cases at the sonic-fluid-throat from the known values of the inlet Mach number, the adiabatic index of the gas and the inlet port diameter of the internal flow system. We found that the 3D blockage factor is 47.33 % lower than the 2D blockage factor with air as the working fluid. We concluded that the exact prediction of the boundary-layer-displacement thickness at the sonic-fluid-throat provides a means to correctly pinpoint the causes of errors of the viscous flow solvers. The methodology presented herein with state-of-the-art will play pivotal roles in future physical and biological sciences for a credible verification, calibration and validation of various viscous flow solvers for high-fidelity 2D/3D numerical simulations of real-world flows. Furthermore, our closed-form analytical model will be useful for the solid and hybrid rocket designers for the grain-port-geometry optimization of new generation single-stage-to-orbit dual-thrust-motors with the highest promising propellant loading density within the given envelope without manifestation of the Sanal flow choking leading to possible shock waves causing catastrophic failures.

  11. Dielectronic recombination theory

    International Nuclear Information System (INIS)

    LaGattuta, K.J.

    1991-01-01

    A theory now in wide use for the calculation of dielectronic recombination cross sections (σ DR ) and rate coefficients (α DR ) was one introduced originally by Feshbach for nuclear physics applications, and then later adapted for atomic scattering problems by Hahn. In the following, we briefly review this theory in a very general form, which allows one to account for the effects of overlapping and interacting resonances, as well as continuum-continuum coupling. An extension of our notation will then also allow for the inclusion of the effects of direct radiative recombination, along with a treatment of the interference between radiative and dielectronic recombination. Other approaches to the calculation of σ DR have been described by Fano and by Seaton. We will not consider those theories here. Calculations of α DR have progressed considerably over the last 25 years, since the early work of Burgess. Advances in the reliability of theoretical predictions have also been promoted recently b a variety of direct laboratory measurements of σ DR . While the measurements of σ DR for δn ≠ 0 excitations have tended to agree very well with calculations, the case of δn = 0 has been much problematic. However, by invoking a mechanism originally proposed by Jacobs, which takes into account the effect of stray electric fields on high Rydberg states (HRS) participating in the DR process, new calculations have improved the agreement between theory and experiment for these cases. Nevertheless, certain discrepancies still remain

  12. Analytical electron microscopy study of surface layers formed on the French SON68 nuclear waste glass during vapor hydration at 200 C

    International Nuclear Information System (INIS)

    Gong, W.L.; Wang, L.M.; Ewing, R.C.; Bates, J.K.; Ebert, W.L.

    1998-01-01

    Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200 C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 μm in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO 2 -rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning among A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results. (orig.)

  13. Stability indicating high performance thin layer chromatographic method for quantitation of venlafaxine in bulk and pharmaceutical dosage form

    Directory of Open Access Journals (Sweden)

    Sunil K Dubey

    2015-01-01

    Full Text Available Background: Venlafaxine (VEN is a phenethylamine bicyclic compound, chemically, 1-(2-[dimethyl amino]-1-[4-methoxy phenyl] ethyl cyclo-hexan-1ol hydrochloride. It is a antidepressant. It inhibits the reuptake of serotonin, nor adrenaline and dopamine to a lesser extent at the presynaptic membrane. Aim: A simple, rapid, precise, accurate, and economical high performance thin layer chromatographic (HPTLC method has been developed and validated for the determination of VEN both as a bulk drug and in formulation. Materials and Methods: The method uses aluminum plates precoated with silica gel 60 F254 as the stationary phase and dichloromethane:acetonitrile:N-hexane:triethylamine: 0.5:0.5:4:0.7 (v/v/v/v as mobile phase. Results: This system gave compact spots for VEN (R f = 0.46 ± 0.05. Forced degradation studies were done by subjecting VEN to acid and alkali hydrolysis, oxidation, and reduction. The peak of the degradation product was well resolved from that of the pure drug and had significant different R f values. Analysis of VEN was performed in the absorbance mode at 225 nm. The limit of detection and quantification were 12.48 and 37.81 ng/spot respectively. Conclusions: The developed method was validated and found to be simple, specific, accurate and precise and can be used for routine quality control analysis of VEN in bulk and pharmaceutical formulation.

  14. Gastrointestinal cell lines form polarized epithelia with an adherent mucus layer when cultured in semi-wet interfaces with mechanical stimulation.

    Science.gov (United States)

    Navabi, Nazanin; McGuckin, Michael A; Lindén, Sara K

    2013-01-01

    Mucin glycoproteins are secreted in large quantities by mucosal epithelia and cell surface mucins are a prominent feature of the glycocalyx of all mucosal epithelia. Currently, studies investigating the gastrointestinal mucosal barrier use either animal experiments or non-in vivo like cell cultures. Many pathogens cause different pathology in mice compared to humans and the in vitro cell cultures used are suboptimal because they are very different from an in vivo mucosal surface, are often not polarized, lack important components of the glycocalyx, and often lack the mucus layer. Although gastrointestinal cell lines exist that produce mucins or polarize, human cell line models that reproducibly create the combination of a polarized epithelial cell layer, functional tight junctions and an adherent mucus layer have been missing until now. We trialed a range of treatments to induce polarization, 3D-organization, tight junctions, mucin production, mucus secretion, and formation of an adherent mucus layer that can be carried out using standard equipment. These treatments were tested on cell lines of intestinal (Caco-2, LS513, HT29, T84, LS174T, HT29 MTX-P8 and HT29 MTX-E12) and gastric (MKN7, MKN45, AGS, NCI-N87 and its hTERT Clone5 and Clone6) origins using Ussing chamber methodology and (immuno)histology. Semi-wet interface culture in combination with mechanical stimulation and DAPT caused HT29 MTX-P8, HT29 MTX-E12 and LS513 cells to polarize, form functional tight junctions, a three-dimensional architecture resembling colonic crypts, and produce an adherent mucus layer. Caco-2 and T84 cells also polarized, formed functional tight junctions and produced a thin adherent mucus layer after this treatment, but with less consistency. In conclusion, culture methods affect cell lines differently, and testing a matrix of methods vs. cell lines may be important to develop better in vitro models. The methods developed herein create in vitro mucosal surfaces suitable for studies

  15. Gastrointestinal cell lines form polarized epithelia with an adherent mucus layer when cultured in semi-wet interfaces with mechanical stimulation.

    Directory of Open Access Journals (Sweden)

    Nazanin Navabi

    Full Text Available Mucin glycoproteins are secreted in large quantities by mucosal epithelia and cell surface mucins are a prominent feature of the glycocalyx of all mucosal epithelia. Currently, studies investigating the gastrointestinal mucosal barrier use either animal experiments or non-in vivo like cell cultures. Many pathogens cause different pathology in mice compared to humans and the in vitro cell cultures used are suboptimal because they are very different from an in vivo mucosal surface, are often not polarized, lack important components of the glycocalyx, and often lack the mucus layer. Although gastrointestinal cell lines exist that produce mucins or polarize, human cell line models that reproducibly create the combination of a polarized epithelial cell layer, functional tight junctions and an adherent mucus layer have been missing until now. We trialed a range of treatments to induce polarization, 3D-organization, tight junctions, mucin production, mucus secretion, and formation of an adherent mucus layer that can be carried out using standard equipment. These treatments were tested on cell lines of intestinal (Caco-2, LS513, HT29, T84, LS174T, HT29 MTX-P8 and HT29 MTX-E12 and gastric (MKN7, MKN45, AGS, NCI-N87 and its hTERT Clone5 and Clone6 origins using Ussing chamber methodology and (immunohistology. Semi-wet interface culture in combination with mechanical stimulation and DAPT caused HT29 MTX-P8, HT29 MTX-E12 and LS513 cells to polarize, form functional tight junctions, a three-dimensional architecture resembling colonic crypts, and produce an adherent mucus layer. Caco-2 and T84 cells also polarized, formed functional tight junctions and produced a thin adherent mucus layer after this treatment, but with less consistency. In conclusion, culture methods affect cell lines differently, and testing a matrix of methods vs. cell lines may be important to develop better in vitro models. The methods developed herein create in vitro mucosal surfaces

  16. Hybrid polymer-CdS solar cell active layers formed by in situ growth of CdS nanoparticles

    International Nuclear Information System (INIS)

    Masala, S.; Del Gobbo, S.; Borriello, C.; Bizzarro, V.; La Ferrara, V.; Re, M.; Pesce, E.; Minarini, C.; De Crescenzi, M.; Di Luccio, T.

    2011-01-01

    The integration of semiconductor nanoparticles (NPs) into a polymeric matrix has the potential to enhance the performance of polymer-based solar cells taking advantage of the physical properties of NPs and polymers. We synthesize a new class of CdS-NPs-based active layer employing a low-cost and low temperature route compatible with large-scale device manufacturing. Our approach is based on the controlled in situ thermal decomposition of a cadmium thiolate precursor in poly(3-hexylthiophene) (P3HT). The casted P3HT:precursor solid foils were heated up from 200 to 300 °C to allow the precursor decomposition and the CdS-NP formation within the polymer matrix. The CdS-NP growth was controlled by varying the annealing temperature. The polymer:precursor weight ratio was also varied to investigate the effects of increasing the NP volume fraction on the solar cell performances. The optical properties were studied by using UV–Vis absorption and photoluminescence (PL) spectroscopy at room temperature. To investigate the photocurrent response of P3HT:CdS nanocomposites, ITO/P3HT:CdS/Al solar cell devices were realized. We measured the external quantum efficiency (EQE) as a function of the wavelength. The photovoltaic response of the devices containing CdS-NPs showed a variation compared with the devices with P3HT only. By changing the annealing temperature the EQE is enhanced in the 400–600 nm spectral region. By increasing the NPs volume fraction remarkable changes in the EQE spectra were observed. The data are discussed also in relation to morphological features of the interfaces studied by Focused Ion Beam technique.

  17. Composition, structure and morphology of oxide layers formed on austenitic stainless steel by oxygen plasma immersion ion implantation

    International Nuclear Information System (INIS)

    Anandan, C.; Rajam, K.S.

    2007-01-01

    Oxygen ions were implanted in to austenitic stainless steel by plasma immersion ion implantation at 400 deg. C. The implanted samples were characterized by XPS, GIXRD, micro-Raman, AFM, optical and scanning electron microscopies. XPS studies showed the presence of Fe in elemental, as Fe 2+ in oxide form and as Fe 3+ in the form of oxyhydroxides in the substrate. Iron was present in the oxidation states of Fe 2+ and Fe 3+ in the implanted samples. Cr and Mn were present as Cr 3+ and Mn 2+ , respectively, in both the substrate and implanted samples. Nickel remained unaffected by implantation. GIXRD and micro-Raman studies showed the oxide to be a mixture of spinel and corundum structures. Optical and AFM images showed an island structure on underlying oxide. This island structure was preserved at different thicknesses. Further, near the grain boundaries more oxide growth was found. This is explained on the basis of faster diffusion of oxygen in the grain boundary regions. Measurement of total hemispherical optical aborptance, α and emittance, ε of the implanted sample show that it has good solar selective properties

  18. Low-Temperature Transformations of Protonic Forms of Layered Complex Oxides HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd)

    International Nuclear Information System (INIS)

    Abdulaeva, L.D.; Silyukov, O.I.; Zvereva, I.A.; Petrov, Yu.V.

    2013-01-01

    In the present work protonic forms of layered Ruddlesden-Popper oxides HLnTiO 4 and H 2 Ln 2 Ti 3 O 10 (Ln = La, Nd) were used as the starting point for soft chemistry synthesis of two series of perovskite-like compounds by acid leaching and exfoliation, promoted by vanadyl sulfate. The last route leads to the nano structured VO 2+ containing samples. Characterization by SEM, powder XRD, and TGA has been performed for the determination of the structure and composition of synthesized oxides

  19. Pock forming ability of fowl pox virus isolated from layer chicken and its adaptation in chicken embryo fibroblast cell culture.

    Science.gov (United States)

    Gilhare, Varsha Rani; Hirpurkar, S D; Kumar, Ashish; Naik, Surendra Kumar; Sahu, Tarini

    2015-03-01

    The objective of the present study was to examine pock forming ability of field strain and vaccine strain of fowl pox virus (FPV) in chorioallantoic membrane (CAM) of embryonated chicken eggs and its adaptation in chicken embryo fibroblast (CEF) cell culture. Dry scabs were collected from 25 affected birds in glycerin-saline and preserved at 4°C until processed. Virus was isolated in 10-day-old embryonated chicken eggs by dropped CAM method. The identity of the virus is confirmed by clinical findings of affected birds, pock morphology and histopathology of infected CAM. In addition one field isolate and vaccine strain of FPV was adapted to CEF cell culture. CEF cell culture was prepared from 9-day-old embryonated chicken eggs. Clinical symptoms observed in affected birds include pox lesion on comb, wattle, eyelids and legs, no internal lesions were observed. All field isolates produced similar findings in CAM. Pocks produced by field isolates ranged from 3 mm to 5 mm at the third passage while initial passages edematous thickening and necrosis of CAM was observed. Pocks formed by lyophilized strain were ranges from 0.5 mm to 2.5 mm in diameter scattered all over the membrane at the first passage. Intra-cytoplasmic inclusion bodies are found on histopathology of CAM. At third passage level, the CEF inoculated with FPV showed characteristic cytopathic effect (CPE) included aggregation of cells, syncytia and plaque formation. FPV field isolates and vaccine strain produced distinct pock lesions on CAMs. Infected CAM showed intracytoplasmic inclusion bodies. The CEF inoculated with FPV field isolate as well as a vaccine strain showed characteristic CPE at third passage level.

  20. Microstructure of buried CoSi2 layers formed by high-dose Co implantation into (100) and (111) Si substrates

    International Nuclear Information System (INIS)

    Bulle-Lieuwma, C.W.T.; Van Ommen, A.H.; Vandenhoudt, D.E.W.; Ottenheim, J.J.M.; de Jong, A.F.

    1991-01-01

    Heteroepitaxial Si/CoSi 2 /Si structures have been synthesized by implanting 170-keV Co + with doses in the range 1--3x10 17 Co + ions/cm 2 into (100) and (111) Si substrates and subsequent annealing. The microstructure of both the as-implanted and annealed structures is investigated in great detail by transmission electron microscopy, high-resolution electron microscopy, and x-ray diffraction. In the as-implanted samples, the Co is present as CoSi 2 precipitates, occurring both in aligned (A-type) and twinned (B-type) orientation. For the highest dose, a continuous layer of stoichiometric CoSi 2 is already formed during implantation. It is found that the formation of a connected layer, already during implantation, is crucial for the formation of a buried CoSi 2 layer upon subsequent annealing. Particular attention is given to the coordination of the interfacial Co atoms at the Si/CoSi 2 (111) interfaces of both types of precipitates. We find that the interfacial Co atoms at the A-type interfaces are fully sevenfold coordinated, whereas at the B-type interfaces they appear to be eightfold coordinated

  1. Optimal properties for coated titanium implants with the hydroxyapatite layer formed by the pulsed laser deposition technique

    Science.gov (United States)

    Himmlova, Lucia; Dostalova, Tatjana; Jelinek, Miroslav; Bartova, Jirina; Pesakova, V.; Adam, M.

    1999-02-01

    Pulsed laser deposition technique allow to 'tailor' bioceramic coat for metal implants by the change of deposition conditions. Each attribute is influenced by the several deposition parameters and each parameter change several various properties. Problem caused that many parameters has an opposite function and improvement of one property is followed by deterioration of other attribute. This study monitor influence of each single deposition parameter and evaluate its importance form the point of view of coat properties. For deposition KrF excimer laser in stainless-steel deposition chamber was used. Deposition conditions (ambient composition and pressures, metallic substrate temperature, energy density and target-substrate distance) were changed according to the film properties. A non-coated titanium implant was used as a control. Films with promising mechanical quality underwent an in vitro biological tests -- measurement of proliferation activity, observing cell interactions with macrophages, fibroblasts, testing toxicity of percolates, observing a solubility of hydroxyapatite (HA) coat. Deposition conditions corresponding with the optimal mechanical and biochemical properties are: metal temperature 490 degrees Celsius, ambient-mixture of argon and water vapor, energy density 3 Jcm-2, target-substrate distance 7.5 cm.

  2. Self-forming Al oxide barrier for nanoscale Cu interconnects created by hybrid atomic layer deposition of Cu–Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae-Hyung; Han, Dong-Suk; Kang, You-Jin [Division of Nanoscale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Shin, So-Ra; Park, Jong-Wan, E-mail: jwpark@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2014-01-15

    The authors synthesized a Cu–Al alloy by employing alternating atomic layer deposition (ALD) surface reactions using Cu and Al precursors, respectively. By alternating between these two ALD surface chemistries, the authors fabricated ALD Cu–Al alloy. Cu was deposited using bis(1-dimethylamino-2-methyl-2-butoxy) copper as a precursor and H{sub 2} plasma, while Al was deposited using trimethylaluminum as the precursor and H{sub 2} plasma. The Al atomic percent in the Cu–Al alloy films varied from 0 to 15.6 at. %. Transmission electron microscopy revealed that a uniform Al-based interlayer self-formed at the interface after annealing. To evaluate the barrier properties of the Al-based interlayer and adhesion between the Cu–Al alloy film and SiO{sub 2} dielectric, thermal stability and peel-off adhesion tests were performed, respectively. The Al-based interlayer showed similar thermal stability and adhesion to the reference Mn-based interlayer. Our results indicate that Cu–Al alloys formed by alternating ALD are suitable seed layer materials for Cu interconnects.

  3. Self-forming Al oxide barrier for nanoscale Cu interconnects created by hybrid atomic layer deposition of Cu–Al alloy

    International Nuclear Information System (INIS)

    Park, Jae-Hyung; Han, Dong-Suk; Kang, You-Jin; Shin, So-Ra; Park, Jong-Wan

    2014-01-01

    The authors synthesized a Cu–Al alloy by employing alternating atomic layer deposition (ALD) surface reactions using Cu and Al precursors, respectively. By alternating between these two ALD surface chemistries, the authors fabricated ALD Cu–Al alloy. Cu was deposited using bis(1-dimethylamino-2-methyl-2-butoxy) copper as a precursor and H 2 plasma, while Al was deposited using trimethylaluminum as the precursor and H 2 plasma. The Al atomic percent in the Cu–Al alloy films varied from 0 to 15.6 at. %. Transmission electron microscopy revealed that a uniform Al-based interlayer self-formed at the interface after annealing. To evaluate the barrier properties of the Al-based interlayer and adhesion between the Cu–Al alloy film and SiO 2 dielectric, thermal stability and peel-off adhesion tests were performed, respectively. The Al-based interlayer showed similar thermal stability and adhesion to the reference Mn-based interlayer. Our results indicate that Cu–Al alloys formed by alternating ALD are suitable seed layer materials for Cu interconnects

  4. Production-ecological analysis of herb layer in the softwood floodplain forests formed after the gabčíkovo waterwork construction and their characteristics

    Directory of Open Access Journals (Sweden)

    Vojtková Jana

    2014-03-01

    Full Text Available This paper is focused on phytocoenological characteristics and production analysis of herbaceous layer biomass of the softwood floodplain forests (Salici-Populetum (R. Tx. 1931 Meijer Drees 1936 association and their phytocoenological characteristics. The sampling site was located in the young stands, which were formed after the Gabčíkovo Waterwork construction in 1992. Redirection of the major ratio of flow into the supply channel has caused essential decrease of water level in the old Danube riverbed. As a result of this, new bare sites have appeared having character of pioneer habitat. In the process of primary succession, new softwood floodplain forests have formed here within a few years. These stands are the subject of the study presented in this paper. We estimated herb layer biomass using indirect sampling modified for non-repeated field measurements (Kubíček, Brechtl, 1970. Total biomass of herbaceous layer was estimated to be 5577 kg ha−1, the aboveground biomass was 4065 kg ha−1 while the belowground biomass was 1512 kg ha−1. The results were compared with the data of Kubíček et al. (2009 and Kollár et al. (2010. Some attention was also paid to their phytocoenologic characteristics. Considering this, it seems that they represent full-value softwood floodplain forest of the Salici-Populetum association despite a bit higher occurrence of some synanthropic species. Such statement is supported by comparison with the data of Jurko (1958 and Šomšák (2003.

  5. Experimentally Studied Thermal Piston-head State of the Internal-Combustion Engine with a Thermal Layer Formed by Micro-Arc Oxidation Method

    Directory of Open Access Journals (Sweden)

    N. Yu. Dudareva

    2015-01-01

    Full Text Available The paper presents results of experimental study to show the efficiency of reducing thermal tension of internal combustion engine (ICE pistons through forming a thermal barrier coating on the piston-head. During the engine operation the piston is under the most thermal stress. High temperatures in the combustion chamber may lead to the piston-head burnout and destruction and engine failure.Micro-arc oxidation (MAO method was selected as the technology to create a thermal barrier coating. MAO technology allows us to form the ceramic coating with a thickness of 400μm on the surface of aluminum alloy, which have high heat resistance, and have good adhesion to the substrate even under thermal cycling stresses.Deliverables of MAO method used to protect pistons described in the scientific literature are insufficient, as they are either calculated or experimentally obtained at the special plants (units, which do not reproduce piston operation in a real engine. This work aims to fill this gap. The aim of the work is an experimental study of the thermal protective ability of MAO-layer formed on the piston-head with simulation of thermal processes of the real engine.The tests were performed on a specially designed and manufactured stand free of motor, which reproduces operation conditions maximum close to those of the real engine. The piston is heated by a fire source - gas burner with isobutene balloon, cooling is carried out by the water circulation system through the water-cooling jacket.Tests have been conducted to compare the thermal state of the regular engine piston without thermal protection and the piston with a heat layer formed on the piston-head by MAO method. The study findings show that the thermal protective MAO-layer with thickness of 100μm allows us to reduce thermal tension of piston on average by 8,5 %. Thus at high temperatures there is the most pronounced effect that is important for the uprated engines.The obtained findings can

  6. On some peculiarities of production of ionospheric equatorial bubbles in zones with increased recombination

    International Nuclear Information System (INIS)

    Vepreva, M.N.; Sazonov, S.V.

    1991-01-01

    Numerical study of dynamics of electromagnetic disturbances of equatorial ionosphere F region which are longitudinal ones relative to B geomagnetic field and occur due to Rayleigh-Taylor and gradient-drift instability activity in zones with increased recombination, is conducted. Arbitrary initial disturbance is determined to be delivered mainly into the first space mode of resonator formed by B force line plunge in high-conducting E layer. Oscillation condition is studied

  7. Recombining without Hotspots: A Comprehensive Evolutionary Portrait of Recombination in Two Closely Related Species of Drosophila

    Science.gov (United States)

    Smukowski Heil, Caiti S.; Ellison, Chris; Dubin, Matthew; Noor, Mohamed A.F.

    2015-01-01

    Meiotic recombination rate varies across the genome within and between individuals, populations, and species in virtually all taxa studied. In almost every species, this variation takes the form of discrete recombination hotspots, determined in some mammals by a protein called PRDM9. Hotspots and their determinants have a profound effect on the genomic landscape, and share certain features that extend across the tree of life. Drosophila, in contrast, are anomalous in their absence of hotspots, PRDM9, and other species-specific differences in the determination of recombination. To better understand the evolution of meiosis and general patterns of recombination across diverse taxa, we present a truly comprehensive portrait of recombination across time, combining recently published cross-based contemporary recombination estimates from each of two sister species with newly obtained linkage-disequilibrium-based historic estimates of recombination from both of these species. Using Drosophila pseudoobscura and Drosophila miranda as a model system, we compare recombination rate between species at multiple scales, and we suggest that Drosophila replicate the pattern seen in human–chimpanzee in which recombination rate is conserved at broad scales. We also find evidence of a species-wide recombination modifier(s), resulting in both a present and historic genome-wide elevation of recombination rates in D. miranda, and identify broad scale effects on recombination from the presence of an inversion. Finally, we reveal an unprecedented view of the distribution of recombination in D. pseudoobscura, illustrating patterns of linked selection and where recombination is taking place. Overall, by combining these estimation approaches, we highlight key similarities and differences in recombination between Drosophila and other organisms. PMID:26430062

  8. Recombining without Hotspots: A Comprehensive Evolutionary Portrait of Recombination in Two Closely Related Species of Drosophila.

    Science.gov (United States)

    Smukowski Heil, Caiti S; Ellison, Chris; Dubin, Matthew; Noor, Mohamed A F

    2015-10-01

    Meiotic recombination rate varies across the genome within and between individuals, populations, and species in virtually all taxa studied. In almost every species, this variation takes the form of discrete recombination hotspots, determined in some mammals by a protein called PRDM9. Hotspots and their determinants have a profound effect on the genomic landscape, and share certain features that extend across the tree of life. Drosophila, in contrast, are anomalous in their absence of hotspots, PRDM9, and other species-specific differences in the determination of recombination. To better understand the evolution of meiosis and general patterns of recombination across diverse taxa, we present a truly comprehensive portrait of recombination across time, combining recently published cross-based contemporary recombination estimates from each of two sister species with newly obtained linkage-disequilibrium-based historic estimates of recombination from both of these species. Using Drosophila pseudoobscura and Drosophila miranda as a model system, we compare recombination rate between species at multiple scales, and we suggest that Drosophila replicate the pattern seen in human-chimpanzee in which recombination rate is conserved at broad scales. We also find evidence of a species-wide recombination modifier(s), resulting in both a present and historic genome-wide elevation of recombination rates in D. miranda, and identify broad scale effects on recombination from the presence of an inversion. Finally, we reveal an unprecedented view of the distribution of recombination in D. pseudoobscura, illustrating patterns of linked selection and where recombination is taking place. Overall, by combining these estimation approaches, we highlight key similarities and differences in recombination between Drosophila and other organisms. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  9. Microstructural study by XPS and GISAXS of surface layers formed via phase separation and percolation in polystyren/tetrabutyl titanate/alumina composite films

    International Nuclear Information System (INIS)

    Zeng Yanwei; Tian Changan; Liu Junliang

    2006-01-01

    The XPS and GISAXS have been employed as useful tools to probe the chemical compositional and microstructural evolutions in the surface layers formed via phase separation and percolation in polystyren/Ti(OBut) 4 /alumina composite thick films. The surface enrichment of Ti species due to the migration of Ti(OBut) 4 molecules in the films was found to show an incubation period of ∼15 h while the samples were treated at 100 deg. C before a remarkable progress can be identified. According to the XPS and GISAXS data, Key mechanism to govern this surface process is phenomenologically considered to be the specific phase separation behavior in Ti(OBut) 4 /PS blend and the subsequent percolating process. The extended thermal treatment was found to make the surface layer microstructure evolve from local phase separation featured with an increasing population of individual microbeads of Ti(OBut) 4 (∼1.5 nm in radius) to the formation of large size clusters of microbeads due to their interconnections, accompanied by the growth of every microbead itself to ∼10 nm on the average, which provokes and then enhances the surface enrichment of Ti(OBut) 4 since these clusters act as a fast diffusion network due to percolation effect

  10. Anhydrous thallium hydrogen L-glutamate: polymer networks formed by sandwich layers of oxygen-coordinated thallium ions cores shielded by hydrogen L-glutamate counterions.

    Science.gov (United States)

    Bodner, Thomas; Wirnsberger, Bianca; Albering, Jörg; Wiesbrock, Frank

    2011-11-07

    Anhydrous thallium hydrogen L-glutamate [Tl(L-GluH)] crystallizes from water (space group P2(1)) with a layer structure in which the thallium ions are penta- and hexacoordinated exclusively by the oxygen atoms of the γ-carboxylate group of the hydrogen L-glutamate anions to form a two-dimensional coordination polymer. The thallium-oxygen layer is composed of Tl(2)O(2) and TlCO(2) quadrangles and is only 3 Å high. Only one hemisphere of the thallium ions participates in coordination, indicative of the presence of the 6s(2) lone pair of electrons. The thallium-oxygen assemblies are shielded by the hydrogen l-glutamate anions. Only the carbon atom of the α-carboxylate group deviates from the plane spanned by the thallium ions, the γ-carboxylate groups and the proton bearing carbon atoms, which are in trans conformation. Given the abundance of L-glutamic and L-aspartic acid in biological systems on the one hand and the high toxicity of thallium on the other hand, it is worth mentioning that the dominant structural motifs in the crystal structure of [Tl(L-GluH)] strongly resemble their corresponding analogues in the crystalline phase of [K(L-AspH)(H(2)O)(2)].

  11. Residual stress determination in oxide layers at different length scales combining Raman spectroscopy and X-ray diffraction: Application to chromia-forming metallic alloys

    Science.gov (United States)

    Guerain, Mathieu; Grosseau-Poussard, Jean-Luc; Geandier, Guillaume; Panicaud, Benoit; Tamura, Nobumichi; Kunz, Martin; Dejoie, Catherine; Micha, Jean-Sebastien; Thiaudière, Dominique; Goudeau, Philippe

    2017-11-01

    In oxidizing environments, the protection of metals and alloys against further oxidation at high temperature is provided by the oxide film itself. This protection is efficient only if the formed film adheres well to the metal (substrate), i.e., without microcracks and spalls induced by thermomechanical stresses. In this study, the residual stresses at both macroscopic and microscopic scales in the oxide film adhering to the substrate and over the damaged areas have been rigorously determined on the same samples for both techniques. Ni-30Cr and Fe-47Cr alloys have been oxidized together at 900 and 1000 °C, respectively, to create films with a thickness of a few microns. A multi-scale approach was adopted: macroscopic stress was determined by conventional X-ray diffraction and Raman spectroscopy, while microscopic residual stress mappings were performed over different types of bucklings using Raman micro-spectroscopy and synchrotron micro-diffraction. A very good agreement is found at macro- and microscales between the residual stress values obtained with both techniques, giving confidence on the reliability of the measurements. In addition, relevant structural information at the interface between the metallic substrate and the oxide layer was collected by micro-diffraction, a non-destructive technique that allows mapping through the oxide layer, and both the grain size and the crystallographic orientation of the supporting polycrystalline metal located either under a buckling or not were measured.

  12. Pinning-free GaAs MIS structures with Si interface control layers formed on (4 x 6) reconstructed (0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Anantathanasarn, Sanguan; Hasegawa, Hideki

    2003-06-30

    (0 0 1)-Oriented GaAs metal-insulator-semiconductor (MIS) structures having a silicon interface control layer (Si ICL) were fabricated on surfaces having Ga-rich (4x6) reconstructions. Si ICL was grown by molecular beam epitaxy. MIS structures were fabricated by partially converting Si ICL to SiN{sub x} by direct nitridation, and further depositing a thick SiO{sub 2} layer on top as the main passivation dielectric by plasma-assisted chemical vapor deposition. Reflection high-energy electron diffraction, in situ X-ray photoelectron spectroscopy and MIS capacitance-voltage (C-V) techniques were used for characterization. The initial surface reconstruction was found to have a surprisingly strong effect on the degree of Fermi level pinning at the MIS interface. In contrast to the standard As-rich (2x4) surface, which results in strongly pinned MIS interfaces, the novel SiO{sub 2}/SiN{sub x}/Si ICL/GaAs MIS structures formed on ''genuine'' (4x6) surface realized complete unpinning of Fermi level over the entire band gap with a minimum interface state density of 4x10{sup 10} cm{sup -2} eV{sup -1} range.

  13. Post-heat treatment of arc-sprayed coating prepared by the wires combination of Mg-cathode and Al-anode to form protective intermetallic layers

    International Nuclear Information System (INIS)

    Xu Rongzheng; Song Gang

    2011-01-01

    A Mg-Al intermetallic compounds coating was prepared on the surface of Mg-steel lap joint by arc-sprayed Al-Mg composite coating (Mg-cathode and Al-anode) and its post-heat treatment (PHT). The effect of PHT temperature on the phase transition, microstructure and mechanical properties of the coating was investigated by X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, optical microscope and microhardness test. The result shows that the intermetallic compounds layer that is mainly composed of Al 3 Mg 2 and Mg 17 Al 12 is formed by the self-diffusion reaction of Mg and Al splats in the coating after PHT for 4 h at 430 deg. C.

  14. Semianalytical Solution for the Deformation of an Elastic Layer under an Axisymmetrically Distributed Power-Form Load: Application to Fluid-Jet-Induced Indentation of Biological Soft Tissues.

    Science.gov (United States)

    Lu, Minhua; Huang, Shuai; Yang, Xianglong; Yang, Lei; Mao, Rui

    2017-01-01

    Fluid-jet-based indentation is used as a noncontact excitation technique by systems measuring the mechanical properties of soft tissues. However, the application of these devices has been hindered by the lack of theoretical solutions. This study developed a mathematical model for testing the indentation induced by a fluid jet and determined a semianalytical solution. The soft tissue was modeled as an elastic layer bonded to a rigid base. The pressure of the fluid jet impinging on the soft tissue was assumed to have a power-form function. The semianalytical solution was verified in detail using finite-element modeling, with excellent agreement being achieved. The effects of several parameters on the solution behaviors are reported, and a method for applying the solution to determine the mechanical properties of soft tissues is suggested.

  15. Therapeutic Recombinant Monoclonal Antibodies

    Science.gov (United States)

    Bakhtiar, Ray

    2012-01-01

    During the last two decades, the rapid growth of biotechnology-derived techniques has led to a myriad of therapeutic recombinant monoclonal antibodies with significant clinical benefits. Recombinant monoclonal antibodies can be obtained from a number of natural sources such as animal cell cultures using recombinant DNA engineering. In contrast to…

  16. Photoionization and Recombination

    Science.gov (United States)

    Nahar, Sultana N.

    2000-01-01

    Theoretically self-consistent calculations for photoionization and (e + ion) recombination are described. The same eigenfunction expansion for the ion is employed in coupled channel calculations for both processes, thus ensuring consistency between cross sections and rates. The theoretical treatment of (e + ion) recombination subsumes both the non-resonant recombination ("radiative recombination"), and the resonant recombination ("di-electronic recombination") processes in a unified scheme. In addition to the total, unified recombination rates, level-specific recombination rates and photoionization cross sections are obtained for a large number of atomic levels. Both relativistic Breit-Pauli, and non-relativistic LS coupling, calculations are carried out in the close coupling approximation using the R-matrix method. Although the calculations are computationally intensive, they yield nearly all photoionization and recombination parameters needed for astrophysical photoionization models with higher precision than hitherto possible, estimated at about 10-20% from comparison with experimentally available data (including experimentally derived DR rates). Results are electronically available for over 40 atoms and ions. Photoionization and recombination of He-, and Li-like C and Fe are described for X-ray modeling. The unified method yields total and complete (e+ion) recombination rate coefficients, that can not otherwise be obtained theoretically or experimentally.

  17. Reassembly of S-layer proteins

    International Nuclear Information System (INIS)

    Pum, Dietmar; Sleytr, Uwe B

    2014-01-01

    Crystalline bacterial cell surface layers (S-layers) represent the outermost cell envelope component in a broad range of bacteria and archaea. They are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. They are highly porous protein mesh works with unit cell sizes in the range of 3 to 30 nm, and pore sizes of 2 to 8 nm. S-layers are usually 5 to 20 nm thick (in archaea, up to 70 nm). S-layer proteins are one of the most abundant biopolymers on earth. One of their key features, and the focus of this review, is the intrinsic capability of isolated native and recombinant S-layer proteins to form self-assembled mono- or double layers in suspension, at solid supports, the air-water interface, planar lipid films, liposomes, nanocapsules, and nanoparticles. The reassembly is entropy-driven and a fascinating example of matrix assembly following a multistage, non-classical pathway in which the process of S-layer protein folding is directly linked with assembly into extended clusters. Moreover, basic research on the structure, synthesis, genetics, assembly, and function of S-layer proteins laid the foundation for their application in novel approaches in biotechnology, biomimetics, synthetic biology, and nanotechnology. (topical review)

  18. Attenuation of an optical wave propagating in a waveguide, formed by layers of a semiconductor heterostructure, owing to scattering on inhomogeneities

    International Nuclear Information System (INIS)

    Bogatov, Alexandr P; Burmistrov, I S

    1999-01-01

    The scattering of an optical wave, propagating in a waveguide made up of layers of a semiconductor heterostructure, is analysed. The attenuation coefficient of the wave is found both for quasi-homogeneous single-crystal layers of a semiconductor solid solution and for layers containing quantum dots. (active media)

  19. Internal mobility of reactive-site-hydrolyzed recombinant Cucurbita maxima trypsin inhibitor-V characterized by NMR spectroscopy: evidence for differential stabilization of newly formed C- and N-termini.

    Science.gov (United States)

    Liu, J; Prakash, O; Huang, Y; Wen, L; Wen, J J; Huang, J K; Krishnamoorthi, R

    1996-09-24

    The solution structure and internal dynamics of the reactive-site (Lys44-Asp45 peptide bond) hydrolyzed form of recombinant Cucurbita maxima trypsin inhibitor-V (rCMTI-V*) were characterized by the application of two-dimensional 1H-15N NMR methods to the uniformly 15N-labeled protein. The 1H-15N chemical shift correlation spectra of rCMTI-V* were assigned, and the chemical shift data were compared with those available for rCMTI-V [Liu, J., Prakash, O., Cai, M., Gong, Y., Huang, Y., Wen, L., Wen, J. J., Huang, J.-K., & Krishnamoorthi, R. (1996) Biochemistry 35, 1516-1524] and CMTI-V* [Cai, M., Gong, Y., Prakash, O., & Krishnamoorthi, R. (1995) Biochemistry 34, 12087-12094] for which three-dimensional solution structures have been determined. It was deduced that the solution structure of rCMTI-V* was almost the same as that of CMTI-V*. 15N spin-lattice and spin-spin relaxation rate constants (R1 and R2, respectively) and ¿1H¿-15N steady-state heteronuclear Overhauser effects were measured for the peptide NH units and arginine and tryptophan N epsilon H groups in rCMTI-V*, and the model-free parameters [Lipari, G., & Szabo, A. (1982) J. Am. Chem. Soc. 104, 4546-4559, 4559-4570] were computed. Most of the backbone of rCMTI-V* is found to be highly constrained (S2 = 0.85), including the N-terminal residues 3-6 (S2 = 0.77). Residues 39-44, forming the C-terminal fragment of the binding loop, exhibit increased mobility (S2 = 0.51); however, the N-terminal segment (residues 46-48) retains rigidity as in the intact form (S2 = 0.83). The S2 values, 0.78 and 0.59, respectively, of Arg50 and Arg52 side chain NHs provide evidence not only for the conservation of the Arg hydrogen-bonds with the binding loop segments but also for the difference in strength between them. This is consistent with the earlier observation made from a study of rCMTI-V at two different pHs and its R50 and R52 mutants [Cai, M., Huang, Y., Prakash, O., Wen, L., Dunkelbarger, S. P., Huang, J.-K., Liu, J

  20. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wijesinghe, W.P.S.L.; Mantilaka, M.M.M.G.P.G.; Chathuranga Senarathna, K.G. [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Herath, H.M.T.U. [Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Department of Medical Laboratory Science, Faculty of Allied Health Sciences, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Premachandra, T.N. [Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Ranasinghe, C.S.K. [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Rajapakse, R.P.V.J. [Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Department of Veterinary Pathobiology, Faculty of Veterinary Medicine, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Rajapakse, R.M.G., E-mail: rmgr@pdn.ac.lk [Department of Chemistry, Faculty of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Postgraduate Institute of Science, University of Peradeniya, 20400 Peradeniya (Sri Lanka); Edirisinghe, Mohan; Mahalingam, S. [Department of Mechanical Engineering, University College London, London WC1E 7JE (United Kingdom); Bandara, I.M.C.C.D. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George Street, Brisbane 4001, QLD (Australia); Singh, Sanjleena [Central Analytical Research Facility, Institute of Future Environments, Queensland University of Technology, 2 George Street, Brisbane 4001, QLD (Australia)

    2016-06-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO{sub 2} thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. - Highlights: • Colloidal hydroxyapatite nanorods are prepared by a novel method. • Surfaces of titanium metal plates are modified by self-forming TiO{sub 2} thin-films. • Prostheses are prepared by coating hydroxyapatite on surface modified Ti metal. • Bioactivity and noncytotoxicity are increased with surface modifications.

  1. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces

    International Nuclear Information System (INIS)

    Wijesinghe, W.P.S.L.; Mantilaka, M.M.M.G.P.G.; Chathuranga Senarathna, K.G.; Herath, H.M.T.U.; Premachandra, T.N.; Ranasinghe, C.S.K.; Rajapakse, R.P.V.J.; Rajapakse, R.M.G.; Edirisinghe, Mohan; Mahalingam, S.; Bandara, I.M.C.C.D.; Singh, Sanjleena

    2016-01-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO_2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. - Highlights: • Colloidal hydroxyapatite nanorods are prepared by a novel method. • Surfaces of titanium metal plates are modified by self-forming TiO_2 thin-films. • Prostheses are prepared by coating hydroxyapatite on surface modified Ti metal. • Bioactivity and noncytotoxicity are increased with surface modifications.

  2. 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)

  3. Improved integration of ultra-thin high-k dielectrics in few-layer MoS2 FET by remote forming gas plasma pretreatment

    Science.gov (United States)

    Wang, Xiao; Zhang, Tian-Bao; Yang, Wen; Zhu, Hao; Chen, Lin; Sun, Qing-Qing; Zhang, David Wei

    2017-01-01

    The effective and high-quality integration of high-k dielectrics on two-dimensional (2D) crystals is essential to the device structure engineering and performance improvement of field-effect transistor (FET) based on the 2D semiconductors. We report a 2D MoS2 transistor with ultra-thin Al2O3 top-gate dielectric (6.1 nm) and extremely low leakage current. Remote forming gas plasma pretreatment was carried out prior to the atomic layer deposition, providing nucleation sites with the physically adsorbed ions on the MoS2 surface. The top gate MoS2 FET exhibited excellent electrical performance, including high on/off current ratio over 109, subthreshold swing of 85 mV/decade and field-effect mobility of 45.03 cm2/V s. Top gate leakage current less than 0.08 pA/μm2 at 4 MV/cm has been obtained, which is the smallest compared with the reported top-gated MoS2 transistors. Such an optimized integration of high-k dielectric in 2D semiconductor FET with enhanced performance is very attractive, and it paves the way towards the realization of more advanced 2D nanoelectronic devices and integrated circuits.

  4. Recombination of cluster ions

    Science.gov (United States)

    Johnsen, Rainer

    1993-01-01

    Some of our recent work on molecular band emissions from recombination of molecular dimer ions (N4(+) and CO(+) CO) is discussed. Much of the experimental work was done by Y. S. Cao; the results on N4(+) recombination have been published. A brief progress report is given on our ongoing measurements of neutral products of recombination using the flowing-afterglow Langmuir-probe technique in conjunction with laser-induced fluorescence.

  5. Passivation layer breakdown during laser-fired contact formation for photovoltaic devices

    International Nuclear Information System (INIS)

    Raghavan, A.; DebRoy, T.; Palmer, T. A.

    2014-01-01

    Low resistance laser-fired ohmic contacts (LFCs) can be formed on the backside of Si-based solar cells using microsecond pulses. However, the impact of these longer pulse durations on the dielectric passivation layer is not clear. Retention of the passivation layer during processing is critical to ensure low recombination rates of electron-hole pairs at the rear surface of the device. In this work, advanced characterization tools are used to demonstrate that although the SiO 2 passivation layer melts directly below the laser, it is well preserved outside the immediate LFC region over a wide range of processing parameters. As a result, low recombination rates at the passivation layer/wafer interface can be expected despite higher energy densities associated with these pulse durations.

  6. Effect of plasma surface functionalization on preosteoblast cells spreading and adhesion on a biomimetic hydroxyapatite layer formed on a titanium surface

    International Nuclear Information System (INIS)

    Myung, Sung Woon; Ko, Yeong Mu; Kim, Byung Hoon

    2013-01-01

    This study examined the plasma surface modification of biomimetic hydroxyapatite (HAp) formed on a titanium (Ti) surface as well as its influence on the behavior of preosteoblast cells. Ti substrates pre-treated with a plasma-polymerized thin film rich in carboxyl groups were subjected to a biomimetic process in a simulated body fluid solution to synthesize the HAp. The HAp layer grown on Ti substrate was then coated with two types of plasma polymerized acrylic acid and allyl amine thin film. The different types of Ti substrates were characterized by attenuated total reflection Fourier transform infrared spectroscopy, energy dispersive spectroscopy and X-ray diffraction. HAp with a Ca/P ratio from 1.25 to 1.38 was obtained on the Ti substrate and hydrophilic carboxyl (-COOH) and amine (-NH 2 ) functional groups were introduced to its surface. Scanning electron microscopy was used to observe the surface of the HAp coatings and the morphology of MC3T3-E1 cells. These results showed that the -COOH-modified HAp surfaces promoted the cell spreading synergistically by changing the surface morphology and chemical state.-NH 2 modified HAp had the lowest cell spreading and proliferation compared to HAp and -COOH-modified HAp. These results correspond to fluorescein analysis, which showed many more cell spreading of COOH/HAp/Ti surface compared to HAp and NH 2 modified HAp. A MTT assay was used to evaluate cell proliferation. The results showed that the proliferation of MC3T3-E1 cells increased in the order of COOH/HAp/Ti > HAp/Ti > NH 2 /Ti > Ti, corresponding to the effect of cell spreading for 6 days. The change in morphology and the chemical surface properties of the biomaterial via plasma polymerization can affect the behavior of MC3T3-E1 cells.

  7. Effect of plasma surface functionalization on preosteoblast cells spreading and adhesion on a biomimetic hydroxyapatite layer formed on a titanium surface

    Energy Technology Data Exchange (ETDEWEB)

    Myung, Sung Woon; Ko, Yeong Mu; Kim, Byung Hoon, E-mail: kim5055@chosun.ac.kr

    2013-12-15

    This study examined the plasma surface modification of biomimetic hydroxyapatite (HAp) formed on a titanium (Ti) surface as well as its influence on the behavior of preosteoblast cells. Ti substrates pre-treated with a plasma-polymerized thin film rich in carboxyl groups were subjected to a biomimetic process in a simulated body fluid solution to synthesize the HAp. The HAp layer grown on Ti substrate was then coated with two types of plasma polymerized acrylic acid and allyl amine thin film. The different types of Ti substrates were characterized by attenuated total reflection Fourier transform infrared spectroscopy, energy dispersive spectroscopy and X-ray diffraction. HAp with a Ca/P ratio from 1.25 to 1.38 was obtained on the Ti substrate and hydrophilic carboxyl (-COOH) and amine (-NH{sub 2}) functional groups were introduced to its surface. Scanning electron microscopy was used to observe the surface of the HAp coatings and the morphology of MC3T3-E1 cells. These results showed that the -COOH-modified HAp surfaces promoted the cell spreading synergistically by changing the surface morphology and chemical state.-NH{sub 2} modified HAp had the lowest cell spreading and proliferation compared to HAp and -COOH-modified HAp. These results correspond to fluorescein analysis, which showed many more cell spreading of COOH/HAp/Ti surface compared to HAp and NH{sub 2} modified HAp. A MTT assay was used to evaluate cell proliferation. The results showed that the proliferation of MC3T3-E1 cells increased in the order of COOH/HAp/Ti > HAp/Ti > NH{sub 2}/Ti > Ti, corresponding to the effect of cell spreading for 6 days. The change in morphology and the chemical surface properties of the biomaterial via plasma polymerization can affect the behavior of MC3T3-E1 cells.

  8. Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces.

    Science.gov (United States)

    Wijesinghe, W P S L; Mantilaka, M M M G P G; Chathuranga Senarathna, K G; Herath, H M T U; Premachandra, T N; Ranasinghe, C S K; Rajapakse, R P V J; Rajapakse, R M G; Edirisinghe, Mohan; Mahalingam, S; Bandara, I M C C D; Singh, Sanjleena

    2016-06-01

    Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700 °C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Effect of atomic layer deposition temperature on current conduction in Al{sub 2}O{sub 3} films formed using H{sub 2}O oxidant

    Energy Technology Data Exchange (ETDEWEB)

    Hiraiwa, Atsushi, E-mail: hiraiwa@aoni.waseda.jp, E-mail: qs4a-hriw@asahi-net.or.jp [Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda-Tsurumaki, Shinjuku, Tokyo 162-0041 (Japan); Matsumura, Daisuke [Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kawarada, Hiroshi, E-mail: kawarada@waseda.jp [Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda-Tsurumaki, Shinjuku, Tokyo 162-0041 (Japan); Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); The Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051 (Japan)

    2016-08-28

    To develop high-performance, high-reliability gate insulation and surface passivation technologies for wide-bandgap semiconductor devices, the effect of atomic layer deposition (ALD) temperature on current conduction in Al{sub 2}O{sub 3} films is investigated based on the recently proposed space-charge-controlled field emission model. Leakage current measurement shows that Al{sub 2}O{sub 3} metal-insulator-semiconductor capacitors formed on the Si substrates underperform thermally grown SiO{sub 2} capacitors at the same average field. However, using equivalent oxide field as a more practical measure, the Al{sub 2}O{sub 3} capacitors are found to outperform the SiO{sub 2} capacitors in the cases where the capacitors are negatively biased and the gate material is adequately selected to reduce virtual dipoles at the gate/Al{sub 2}O{sub 3} interface. The Al{sub 2}O{sub 3} electron affinity increases with the increasing ALD temperature, but the gate-side virtual dipoles are not affected. Therefore, the leakage current of negatively biased Al{sub 2}O{sub 3} capacitors is approximately independent of the ALD temperature because of the compensation of the opposite effects of increased electron affinity and permittivity in Al{sub 2}O{sub 3}. By contrast, the substrate-side sheet of charge increases with increasing ALD temperature above 210 °C and hence enhances the current of positively biased Al{sub 2}O{sub 3} capacitors more significantly at high temperatures. Additionally, an anomalous oscillatory shift of the current-voltage characteristics with ALD temperature was observed in positively biased capacitors formed by low-temperature (≤210 °C) ALD. This shift is caused by dipoles at the Al{sub 2}O{sub 3}/underlying SiO{sub 2} interface. Although they have a minimal positive-bias leakage current, the low-temperature-grown Al{sub 2}O{sub 3} films cause the so-called blisters problem when heated above 400 °C. Therefore, because of the absence of blistering, a 450

  10. Characterization Of Oxide Layers Formed On 13CrMo4-5 Steel Operated For A Long Time At An Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Gwoździk M.

    2015-09-01

    Full Text Available The paper contains results of studies into the formation of oxide layers on 13CrMo4-5 (15HM steel long-term operated at an elevated temperature. The oxide layer was studied on a surface and a cross-section at the inner and outer surface of the tube wall. The 13CrMo4-5 steel operated at the temperature of 470°C during 190,000 hours was investigated. X-ray structural examinations (XRD were carried out, microscope observation s using an optical, scanning microscope were performed. The native material chemical composition was analysed by means of emission spark spectroscopy, while that of oxide layers on a scanning microscope (EDS. The studies on the topography of the oxide layers comprised studies on the roughness plane, which were carried out using a AFM microscope designed for 2D and 3D studies on the surface. Mechanical properties of the oxide layer – steel (substrate were characterised on the basis of scratch test. The adhesion of oxide layers, friction force, friction coefficient, scratching depth were determined as well as the force at which the layer was delaminated.

  11. Characterization and diffusion model for the titanium boride layers formed on the Ti6Al4V alloy by plasma paste boriding

    Energy Technology Data Exchange (ETDEWEB)

    Keddam, Mourad, E-mail: keddam@yahoo.fr [Laboratoire de Technologie des Matériaux, Faculté de Génie Mécanique et Génie des Procédés, USTHB, B.P. No. 32, 16111 El-Alia, Bab-Ezzouar, Algiers (Algeria); Taktak, Sukru [Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, ANS Campus, 03200, Afyonkarahisar (Turkey)

    2017-03-31

    Highlights: • Titanium boride layers were produced by plasma paste boriding on Ti6Al4V at 973–1073 K. • Formation rates of the Ti boride layers have parabolic character at all temperatures. • Boron diffusivities were estimated using a diffusion model including incubation times. • Activation energies of boron in TiB{sub 2} and TiB were 136 and 63 kJ/mol respectively. - Abstract: The present study is focused on the estimation of activation energy of boron in the plasma paste borided Ti6Al4V alloy, which is extensively used in technological applications, using an analytical diffusion model. Titanium boride layers were successfully produced by plasma paste boriding method on the Ti6Al4V alloy in the temperature range of 973–1073 K for a treatment time ranging from 3 to 7 h. The presence of both TiB{sub 2} top-layer and TiB whiskers sub-layer was confirmed by the XRD analysis and SEM observations. The surface hardness of the borided alloy was evaluated using Micro-Knoop indenter. The formation rates of the TiB{sub 2} and TiB layers were found to have a parabolic character at all applied process temperatures. A diffusion model was suggested to estimate the boron diffusivities in TiB{sub 2} and TiB layers under certain assumptions, by considering the effect of boride incubation times. Basing on own experimental data on boriding kinetics, the activation energies of boron in TiB{sub 2} and TiB phases were estimated as 136.24 ± 0.5 and 63.76 ± 0.5 kJ mol{sup −1}, respectively. Finally, the obtained values of boron activation energies for Ti6Al4V alloy were compared with the data available in the literature.

  12. Enhancement of the surface methane hydrate-bearing layer based on the specific microorganisms form deep seabed sediment in Japan Sea.

    Science.gov (United States)

    Hata, T.; Yoneda, J.; Yamamoto, K.

    2017-12-01

    A methane hydrate-bearing layer located near the Japan Sea has been investigated as a new potential energy resource. In this study examined the feasibility of the seabed surface sediment strength located in the Japan Sea improvement technologies for enhancing microbial induced carbonate precipitation (MICP) process. First, the authors cultivated the specific urease production bacterium culture medium from this surface methane hydrate-bearing layer in the seabed (-600m depth) of Japan Sea. After that, two types of the laboratory test (consolidated-drained triaxial tests) were conducted using this specific culture medium from the seabed in the Japan Sea near the Toyama Prefecture and high urease activities bacterium named Bacillus pasteurii. The main outcomes of this research are as follows. 1) Specific culture medium focused on the urease production bacterium can enhancement of the urease activities from the methane hydrate-bearing layer near the Japan Sea side, 2) This specific culture medium can be enhancement of the surface layer strength, 3) The microbial induced carbonate precipitation process can increase the particle size compared to that of the original particles coating the calcite layer surface, 4) The mechanism for increasing the soil strength is based on the addition of cohesion like a cement stabilized soil.

  13. Layering and Ordering in Electrochemical Double Layers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yihua [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Kawaguchi, Tomoya [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Pierce, Michael S. [Rochester Institute of Technology, School of Physics and Astronomy, Rochester, New York 14623, United States; Komanicky, Vladimir [Faculty of Science, Safarik University, 041 54 Kosice, Slovakia; You, Hoydoo [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States

    2018-02-26

    Electrochemical double layers (EDL) form at electrified interfaces. While Gouy-Chapman model describes moderately charged EDL, formation of Stern layers was predicted for highly charged EDL. Our results provide structural evidence for a Stern layer of cations, at potentials close to hydrogen evolution in alkali fluoride and chloride electrolytes. Layering was observed by x-ray crystal truncation rods and atomic-scale recoil responses of Pt(111) surface layers. Ordering in the layer is confirmed by glancing-incidence in-plane diffraction measurements.

  14. Intermediate bands versus levels in non-radiative recombination

    International Nuclear Information System (INIS)

    Luque, Antonio; Marti, Antonio; Antolin, Elisa; Tablero, Cesar

    2006-01-01

    There is a practical interest in developing semiconductors with levels situated within their band gap while preventing the non-radiative recombination that these levels promote. In this paper, the physical causes of this non-radiative recombination are analyzed and the increase in the density of the impurities responsible for the mid-gap levels to the point of forming bands is suggested as the means of suppressing the recombination. Simple models supporting this recommendation and helping in its quantification are presented

  15. Quantum confined laser devices optical gain and recombination in semiconductors

    CERN Document Server

    Blood, Peter

    2015-01-01

    The semiconductor laser, invented over 50 years ago, has had an enormous impact on the digital technologies that now dominate so many applications in business, commerce and the home. The laser is used in all types of optical fibre communication networks that enable the operation of the internet, e-mail, voice and skype transmission. Approximately one billion are produced each year for a market valued at around $5 billion. Nearly all semiconductor lasers now use extremely thin layers of light emitting materials (quantum well lasers). Increasingly smaller nanostructures are used in the form of quantum dots. The impact of the semiconductor laser is surprising in the light of the complexity of the physical processes that determine the operation of every device. This text takes the reader from the fundamental optical gain and carrier recombination processes in quantum wells and quantum dots, through descriptions of common device structures to an understanding of their operating characteristics. It has a consistent...

  16. Activated recombinant adenovirus proteinases

    Science.gov (United States)

    Anderson, Carl W.; Mangel, Walter F.

    1999-08-10

    This application describes methods and expression constructs for producing activatable recombinant adenovirus proteinases. Purified activatable recombinant adenovirus proteinases and methods of purification are described. Activated adenovirus proteinases and methods for obtaining activated adenovirus proteinases are further included. Isolated peptide cofactors of adenovirus proteinase activity, methods of purifying and identifying said peptide cofactors are also described. Antibodies immunoreactive with adenovirus proteinases, immunospecific antibodies, and methods for preparing them are also described. Other related methods and materials are also described.

  17. Hadron correlations from recombination

    Energy Technology Data Exchange (ETDEWEB)

    Fries, Rainer J [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2005-01-01

    Quark recombination is a successful model to describe the hadronization of a deconfined quark gluon plasma. Jet-like dihadron correlations measured at RHIC provide a challenge for this picture. We discuss how correlations between hadrons can arise from correlations between partons before hadronization. An enhancement of correlations through the recombination process, similar to the enhancement of elliptic flow is found. Hot spots from completely or partially quenched jets are a likely source of such parton correlations.

  18. Evidence for possible biological advantages of the newly emerging HIV-1 circulating recombinant form from Malaysia - CRF33_01B in comparison to its progenitors - CRF01_AE and subtype B.

    Science.gov (United States)

    Lau, Katherine A; Wang, Bin; Miranda-Saksena, Monica; Boadle, Ross; Kamarulzaman, Adeeba; Ng, Kee-Peng; Saksena, Nitin K

    2010-04-01

    In Malaysia, co-circulation of CRF01_AE and subtype B has resulted in the emergence of the second generation derivative; CRF33_01B in approximately 20% of its HIV-1 infected individuals. Our objective was to identify possible biological advantages that CRF33_01B possesses over its progenitors. Biological and molecular comparisons of CRF33_01B against its parental subtypes clearly show that CRF33_01B replicated better in activated whole peripheral blood mononuclear cells (PBMCs) and CD4+ T-lymphocytes, but not monocyte-derived macrophages (MDMs). Also, its acquired fitness was greater than CRF01_AE but not subtype B. Moreover, CRF33_01B has higher rate of apoptotic cell death and syncytia induction compared to subtype B. These adaptive and survival abilities could have been acquired by CRF33_01B due to the incorporation of subtype B fragments into the gag-RT region of its full-length genome. Our studies confirm the previously held belief that HIV-1 strains may harbor enhanced biological fitness upon recombination. We therefore estimate a possible gradual replacement of the current predominance of CRF01_AE, as well as wider dissemination of CRF33_01B, together with the identification of other new CRF01_AE/B inter-subtype recombinants in Malaysia.

  19. Seed morphology, germination phenology, and capacity to form a seed bank in six herbaceous layer apiaceae species of the eastern deciduous forest

    Science.gov (United States)

    Tracy S. Hawkins; Jerry M. Baskin; Carol C. Baskin

    2007-01-01

    We compared seed mass, seed morphology, and long-term germination phenology of three monocarpic (MI and three polycarpic (P) Apiaceae species of the herbaceous layer of the Eastern Deciduous Forest. Seeds (mericarps) of the six species differed considerably in mass, shape, and ornamentation. Mean seed masses were ranked Cryptotaenia canadensis (M)...

  20. Nonvolatile memory thin film transistors using CdSe/ZnS quantum dot-poly(methyl methacrylate) composite layer formed by a two-step spin coating technique

    Science.gov (United States)

    Chen, Ying-Chih; Huang, Chun-Yuan; Yu, Hsin-Chieh; Su, Yan-Kuin

    2012-08-01

    The nonvolatile memory thin film transistors (TFTs) using a core/shell CdSe/ZnS quantum dot (QD)-poly(methyl methacrylate) (PMMA) composite layer as the floating gate have been demonstrated, with the device configuration of n+-Si gate/SiO2 insulator/QD-PMMA composite layer/pentacene channel/Au source-drain being proposed. To achieve the QD-PMMA composite layer, a two-step spin coating technique was used to successively deposit QD-PMMA composite and PMMA on the insulator. After the processes, the variation of crystal quality and surface morphology of the subsequent pentacene films characterized by x-ray diffraction spectra and atomic force microscopy was correlated to the two-step spin coating. The crystalline size of pentacene was improved from 147.9 to 165.2 Å, while the degree of structural disorder was decreased from 4.5% to 3.1% after the adoption of this technique. In pentacene-based TFTs, the improvement of the performance was also significant, besides the appearances of strong memory characteristics. The memory behaviors were attributed to the charge storage/discharge effect in QD-PMMA composite layer. Under the programming and erasing operations, programmable memory devices with the memory window (Δ Vth) = 23 V and long retention time were obtained.

  1. Recombinant human erythropoietin in sports: a review

    Directory of Open Access Journals (Sweden)

    Rafael Maia de Almeida Bento

    2003-06-01

    Full Text Available Erythropoietin is an endogenous hormone of glicoproteic nature secreted by the kidneys and is the main regulator of the erythropoiesis. An alteration in its production generates a disturbance in the plasmatic concentration giving rise to several types of pathologies related to the hematopoietic system. The recombinant forms of erythropoietin have indiscriminately been used by athletes, mainly in endurance sports, by increasing the erythrocytes concentration, generating a better delivery of oxygen to the muscle tissue. The administration of recombinant erythropoietin was prohibited by the International Olympic Committee and its use considered as doping. This review has the intention to describe the physical, biological and pharmacokinetic properties of the endogenous erythropoietin, as well as its recombinant form, describing also its use in sports and the process of searching methodologies for its detection in doping control.

  2. Mitochondrial recombination increases with age in Podospora anserina

    NARCIS (Netherlands)

    van Diepeningen, Anne D; Goedbloed, Daniël J; Slakhorst, S Marijke; Koopmanschap, A Bertha; Maas, Marc F P M; Hoekstra, Rolf F; Debets, Alfons J M

    With uniparental inheritance of mitochondria, there seems little reason for homologous recombination in mitochondria, but the machinery for mitochondrial recombination is quite well-conserved in many eukaryote species. In fungi and yeasts heteroplasmons may be formed when strains fuse and transfer

  3. Application of XPS and nuclear technique to the study of the gel layers formed under different redex conditions on leached glasses

    International Nuclear Information System (INIS)

    Manara, A.; Lanza, F.; Ceccone, G.; Della Mea, G.; Salvagno, G.

    1984-01-01

    Surface analysis has been conducted on samples leached in a Soxhlet apparatus at 100 0 C in presence and in absence of air. The XPS and RBS techniques were applied to analyse the content of the silicon, iron and uranium while the nuclear reaction method was utilized to analyse the hydrogen content. The anoxic environment favors the release of iron while decreasing the dissolution of uranium. Hydrogen content is always higher in samples leached in presence of air. Silicon depletion is evident in all cases. The diffusion process seems to regulate the growth of the layer on the glass surface. After long leaching time a detachment, at least partial, of this layer is observed. 14 refs., 9 figs., 1 tab

  4. Examining the evolution towards turbulence through spatio-temporal analysis of multi-dimensional structures formed by instability growth along a shear layer

    Science.gov (United States)

    Merritt, Elizabeth; Doss, Forrest; Loomis, Eric; Flippo, Kirk; Devolder, Barbara; Welser-Sherrill, Leslie; Fincke, James; Kline, John

    2014-10-01

    The counter-propagating shear campaign is examining instability growth and its transition to turbulence relevant to mix in ICF capsules. Experimental platforms on both OMEGA and NIF use anti-symmetric flows about a shear interface to examine isolated Kelvin-Helmholtz instability growth. Measurements of interface (an Al or Ti tracer layer) dynamics are used to benchmark the LANL RAGE hydrocode with BHR turbulence model. The tracer layer does not expand uniformly, but breaks up into multi-dimensional structures that are initially quasi-2D due to the target geometry. We are developing techniques to analyze the multi-D structure growth along the tracer surface with a focus on characterizing the time-dependent structures' spectrum of scales in order to appraise a transition to turbulence in the system and potentially provide tighter constraints on initialization schemes for the BHR model. To this end, we use a wavelet based analysis to diagnose single-time radiographs of the tracer layer surface (w/low and amplified roughness for random noise seeding) with observed spatially non-repetitive features, in order to identify spatial and temporal trends in radiographs taken at different times across several experimental shots. This work conducted under the auspices of the U.S. Department of Energy by LANL under Contract DE-AC52-06NA25396.

  5. Regulation of Meiotic Recombination

    Energy Technology Data Exchange (ETDEWEB)

    Gregory p. Copenhaver

    2011-11-09

    Meiotic recombination results in the heritable rearrangement of DNA, primarily through reciprocal exchange between homologous chromosome or gene conversion. In plants these events are critical for ensuring proper chromosome segregation, facilitating DNA repair and providing a basis for genetic diversity. Understanding this fundamental biological mechanism will directly facilitate trait mapping, conventional plant breeding, and development of genetic engineering techniques that will help support the responsible production and conversion of renewable resources for fuels, chemicals, and the conservation of energy (1-3). Substantial progress has been made in understanding the basal recombination machinery, much of which is conserved in organisms as diverse as yeast, plants and mammals (4, 5). Significantly less is known about the factors that regulate how often and where that basal machinery acts on higher eukaryotic chromosomes. One important mechanism for regulating the frequency and distribution of meiotic recombination is crossover interference - or the ability of one recombination event to influence nearby events. The MUS81 gene is thought to play an important role in regulating the influence of interference on crossing over. The immediate goals of this project are to use reverse genetics to identify mutants in two putative MUS81 homologs in the model plant Arabidopsis thaliana, characterize those mutants and initiate a novel forward genetic screen for additional regulators of meiotic recombination. The long-term goal of the project is to understand how meiotic recombination is regulated in higher eukaryotes with an emphasis on the molecular basis of crossover interference. The ability to monitor recombination in all four meiotic products (tetrad analysis) has been a powerful tool in the arsenal of yeast geneticists. Previously, the qrt mutant of Arabidopsis, which causes the four pollen products of male meiosis to remain attached, was developed as a facile system

  6. Recombinational repair: workshop summary

    International Nuclear Information System (INIS)

    Howard-Flanders, P.

    1983-01-01

    Recombinational repair may or may not be synonymous with postreplication repair. Considerable progress has been made in the study of the relevant enzymes, particularly those from bacteria. In this workshop we focus on the recombination enzyme RecA protein. What structural changes take place in the protein and in DNA during repair. How does homologous pairing take place. How is ATP hydrolysis coupled to the stand exchange reaction and the formation of heteroduplx DNA. Turning to another enzyme needed for certain kinds of bacterial recombination, we will ask whether the purified recB protein and recC protein complement each other and are sufficient for exonuclease V activity. In higher cells, we would like to know whether sister exchanges, which occur in bacteria after uv irradiation, are also seen in animal cells

  7. Fundamental Studies of Recombinant Hydrogenases

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Michael W. [Univ. of Georgia, Athens, GA (United States)

    2014-01-25

    This research addressed the long term goals of understanding the assembly and organization of hydrogenase enzymes, of reducing them in size and complexity, of determining structure/function relationships, including energy conservation via charge separation across membranes, and in screening for novel H2 catalysts. A key overall goal of the proposed research was to define and characterize minimal hydrogenases that are produced in high yields and are oxygen-resistant. Remarkably, in spite of decades of research carried out on hydrogenases, it is not possible to readily manipulate or design the enzyme using molecular biology approaches since a recombinant form produced in a suitable host is not available. Such resources are essential if we are to understand what constitutes a “minimal” hydrogenase and design such catalysts with certain properties, such as resistance to oxygen, extreme stability and specificity for a given electron donor. The model system for our studies is Pyrococcus furiosus, a hyperthermophile that grows optimally at 100°C, which contains three different nickel-iron [NiFe-] containing hydrogenases. Hydrogenases I and II are cytoplasmic while the other, MBH, is an integral membrane protein that functions to both evolve H2 and pump protons. Three important breakthroughs were made during the funding period with P. furiosus soluble hydrogenase I (SHI). First, we produced an active recombinant form of SHI in E. coli by the co-expression of sixteen genes using anaerobically-induced promoters. Second, we genetically-engineered P. furiosus to overexpress SHI by an order of magnitude compared to the wild type strain. Third, we generated the first ‘minimal’ form of SHI, one that contained two rather than four subunits. This dimeric form was stable and active, and directly interacted with a pyruvate-oxidizing enzyme with any intermediate electron carrier. The research resulted in five peer-reviewed publications.

  8. Electron - ion recombination processes - an overview

    International Nuclear Information System (INIS)

    Hahn, Yukap

    1997-01-01

    Extensive theoretical and experimental studies have been carried out for the past 20 years on electron - ion recombination processes, as they are applied to the analysis of astrophysical and laboratory plasmas. We review the basic understanding gained through these efforts, with emphasis on some of the more recent progress made in recombination theory as the recombining system is affected by time-dependent electric fields and plasma particles at low temperature. Together with collisional ionization and excitation processes, recombination is important in determining ionization balance and excited-state population in non-equilibrium plasmas. The radiation emitted by plasmas is usually the principal medium with which to study the plasma condition, as it is produced mainly during the recombination and decay of excited states of ions inside the plasma. This is especially true when the plasma under study is not readily accessible by direct probes, as in astrophysical plasmas. Moreover, external probes may sometimes cause undesirable disturbances of the plasma. Electron-ion recombination proceeds in several different modes. The direct modes include three-body recombination (TBR) and one-step radiative recombination (RR), all to the ground- and singly-excited states of the target ions. By contrast, the indirect resonant mode is a two-step dielectronic recombination (DR), which proceeds first with the formation of doubly-excited states by radiationless excitation/capture. The resonant states thus formed may relax by autoionization and/or radiative cascades. For more exotic modes of recombination, we consider off-shell dielectronic recombination (radiative DR = RDR), in which an electron capture is accompanied by simultaneous radiative emission and excitation of the target ion. Some discussion on attachment of electrons to neutral atoms, resulting in the formation of negative ions, is also given. When resonance states involve one or more electrons in high Rydberg states

  9. Low-temperature radiative recombination of electrons with bare nuclei

    International Nuclear Information System (INIS)

    Omidvar, K.

    1993-01-01

    Aside from empirical formulas, the radiative-recombination cross section and coefficient are usually given in tabulated forms instead of analytic formulas. Here, we give analytic expressions in the form of expansions for the recombination cross section as a function of the electron energy E for low E, and for the recombination coefficient as a function of the temperature T for low T. The expansion coefficients are combinations of confluent hypergeometric functions, and are tabulated for a large number of the final principal and angular-momentum quantum numbers n and l. It is shown that the recombination cross section for arbitrary nuclear charge number Z is independent of Z, while the recombination coefficient for T/Z 2 much-lt 1.58x10 5 K increases as Z 2 . Excellent agreement is found with the published tabulated values

  10. Analysis of the Tb{sup 3+} recombination in ion implanted Al{sub x}Ga{sub 1−x}N (0≤x≤1) layers

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, J., E-mail: joana.catarina@ua.pt [Departamento de Física e I3N, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Fialho, M.; Magalhães, S. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal); Correia, M.R.; Rino, L. [Departamento de Física e I3N, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Alves, E. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal); Neves, A.J. [Departamento de Física e I3N, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Lorenz, K. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal); Monteiro, T. [Departamento de Física e I3N, Universidade de Aveiro, 3810-193 Aveiro (Portugal)

    2016-10-15

    Al{sub x}Ga{sub 1−x}N layers with different AlN molar fractions, 0≤x≤1, implanted with Tb{sup 3+} ions were characterized using structural and optical techniques. After adequate thermal annealing treatments, all the layers evidence the {sup 5}D{sub 4}→{sup 7}F{sub J} intra-4f{sup 8} transitions. The green emission from the {sup 5}D{sub 4} emitting level can be identified up to room temperature in samples with x≥0.53. The preferential population paths of the Tb{sup 3+} luminescence were assessed by photoluminescence excitation at RT where two main broad subgap excitation bands peaked at ~270 nm and ~300 nm were found for the layers with higher aluminium content. The analysis of the temperature-dependent Tb{sup 3+} integrated luminescence reveals distinct activation energies for different compositions, with AlN:Tb showing the highest thermal stability for the intraionic luminescence. The ion excitation paths are discussed on a basis of excitonic features and compared with the trend observed for other rare earth ions in nitrides, as well as theoretical predictions. A single exponential decay for the {sup 5}D{sub 4}→{sup 7}F{sub 6} transition was measured at RT and the lifetime of the transition was found to increase with increasing composition revealing the sensitivity of the ions to the surrounding medium.

  11. Parton recombination model

    International Nuclear Information System (INIS)

    Hwa, R.C.

    1978-08-01

    Low P/sub T/ meson production in hadronic collisions is described in the framework of the parton model. The recombination of quark and antiquark is suggested as the dominant mechanism in the large x region. Phenomenological evidences for the mechanism are given. The application to meson initiated reactions yields the quark distribution in mesons. 21 references

  12. Influence of a deep-level-defect band formed in a heavily Mg-doped GaN contact layer on the Ni/Au contact to p-GaN

    International Nuclear Information System (INIS)

    Li Xiao-Jing; Zhao De-Gang; Jiang De-Sheng; Chen Ping; Zhu Jian-Jun; Liu Zong-Shun; Yang Jing; He Xiao-Guang; Yang Hui; Zhang Li-Qun; Zhang Shu-Ming; Le Ling-Cong; Liu Jian-Ping

    2015-01-01

    The influence of a deep-level-defect (DLD) band formed in a heavily Mg-doped GaN contact layer on the performance of Ni/Au contact to p-GaN is investigated. The thin heavily Mg-doped GaN (p ++ -GaN) contact layer with DLD band can effectively improve the performance of Ni/Au ohmic contact to p-GaN. The temperature-dependent I–V measurement shows that the variable-range hopping (VRH) transportation through the DLD band plays a dominant role in the ohmic contact. The thickness and Mg/Ga flow ratio of p ++ -GaN contact layer have a significant effect on ohmic contact by controlling the Mg impurity doping and the formation of a proper DLD band. When the thickness of the p ++ -GaN contact layer is 25 nm thick and the Mg/Ga flow rate ratio is 10.29%, an ohmic contact with low specific contact resistivity of 6.97× 10 −4 Ω·cm 2 is achieved. (paper)

  13. Stability indicating high performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in combined dosage form

    Directory of Open Access Journals (Sweden)

    Deepak Bageshwar

    2011-11-01

    Full Text Available A specific, precise and stability indicating high-performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in pharmaceutical formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F254 as the stationary phase. The solvent system consisted of methanol:water:ammonium acetate; 4.0:1.0:0.5 (v/v/v. This system was found to give compact and dense spots for both itopride hydrochloride (Rf value of 0.55±0.02 and pantoprazole sodium (Rf value of 0.85±0.04. Densitometric analysis of both drugs was carried out in the reflectance–absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9988±0.0012 in the concentration range of 100–400 ng for pantoprazole sodium. Also, the linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9990±0.0008 in the concentration range of 200–1200 ng for itopride hydrochloride. The method was validated for specificity, precision, robustness and recovery. Statistical analysis proves that the method is repeatable and selective for the estimation of both the said drugs. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating method. Keywords: Gastroesophageal reflux disease (GERD, Itopride hydrochloride, Pantoprazole sodium, High performance thin layer chromatography (HPTLC, Stability indicating, Forced degradation

  14. Interfacial, Electrical, and Band Alignment Characteristics of HfO2/Ge Stacks with In Situ-Formed SiO2 Interlayer by Plasma-Enhanced Atomic Layer Deposition

    Science.gov (United States)

    Cao, Yan-Qiang; Wu, Bing; Wu, Di; Li, Ai-Dong

    2017-05-01

    In situ-formed SiO2 was introduced into HfO2 gate dielectrics on Ge substrate as interlayer by plasma-enhanced atomic layer deposition (PEALD). The interfacial, electrical, and band alignment characteristics of the HfO2/SiO2 high-k gate dielectric stacks on Ge have been well investigated. It has been demonstrated that Si-O-Ge interlayer is formed on Ge surface during the in situ PEALD SiO2 deposition process. This interlayer shows fantastic thermal stability during annealing without obvious Hf-silicates formation. In addition, it can also suppress the GeO2 degradation. The electrical measurements show that capacitance equivalent thickness of 1.53 nm and a leakage current density of 2.1 × 10-3 A/cm2 at gate bias of Vfb + 1 V was obtained for the annealed sample. The conduction (valence) band offsets at the HfO2/SiO2/Ge interface with and without PDA are found to be 2.24 (2.69) and 2.48 (2.45) eV, respectively. These results indicate that in situ PEALD SiO2 may be a promising interfacial control layer for the realization of high-quality Ge-based transistor devices. Moreover, it can be demonstrated that PEALD is a much more powerful technology for ultrathin interfacial control layer deposition than MOCVD.

  15. 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

  16. 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.

  17. Teaching Form as Form

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    understanding of form per se, or, to use an expression from this text, of form as form. This challenge can be reduced to one question: how can design teaching support students in achieving not only the ability to recognize and describe different form-related concepts in existing design (i.e. analytical...

  18. Chemical properties of various organic electrolytes for lithium rechargeable batteries. Pt. 1.. Characterization of passivating layer formed on graphite in alkyl carbonate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Shoichiro; Asahina, Hitoshi; Suzuki, Hitoshi; Yonei, Ayako; Yokoto, Kiyomi [Tsukuba Research Center, Mitsubishi Chemical Corporation, Ibaraki (Japan)

    1997-09-01

    The characteristics and reaction mechanisms of the passivating film formed on the surface of graphite were investigated in ethylene carbonate-diethyl carbonate solutions containing LiClO{sub 4}, LiPF{sub 6} and LiN(SO{sub 2}CF{sub 3}){sub 2}. The electron consumption resulting on the irreversible capacity of graphite was almost equivalent to that used in the one-electron reduction of Li{sup +} found in the film. The electrochemical reactions in the first discharge process may be divided into the following steps: (i) `initial film formation step` from 1.4 to 0.55 V; (ii) `main film formation step` from 0.55 to 0.2 V, and (iii) `lithium intercalation step from 0.2 to 0.0 V. Most of the passivating film is formed together with the lithium intercalation reaction at step (ii). The passivating film formed at this step contained a significant amount of organic film such as EtOCO{sub 2}Li, (CH{sub 2}OCO{sub 2}Li){sub 2}, etc. Through the consecutive formation of passivating film at steps (i) and (ii), lithium intercalation into graphite proceeds smoothly without further decomposition of organic electrolyte. (orig.)

  19. Layered materials

    Science.gov (United States)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  20. Stability indicating high performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in combined dosage form.

    Science.gov (United States)

    Bageshwar, Deepak; Khanvilkar, Vineeta; Kadam, Vilasrao

    2011-11-01

    A specific, precise and stability indicating high-performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in pharmaceutical formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F 254 as the stationary phase. The solvent system consisted of methanol:water:ammonium acetate; 4.0:1.0:0.5 (v/v/v). This system was found to give compact and dense spots for both itopride hydrochloride ( R f value of 0.55±0.02) and pantoprazole sodium ( R f value of 0.85±0.04). Densitometric analysis of both drugs was carried out in the reflectance-absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with R 2 =0.9988±0.0012 in the concentration range of 100-400 ng for pantoprazole sodium. Also, the linear regression analysis data for the calibration plots showed a good linear relationship with R 2 =0.9990±0.0008 in the concentration range of 200-1200 ng for itopride hydrochloride. The method was validated for specificity, precision, robustness and recovery. Statistical analysis proves that the method is repeatable and selective for the estimation of both the said drugs. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating method.

  1. Acetate-intercalated Ni–In layered double hydroxides with low infrared emissivity: Synthesis, delamination and restacked to form the multilayer films

    International Nuclear Information System (INIS)

    Wang, Yongjuan; Zhou, Yuming; Zhang, Tao; He, Man; Bu, Xiaohai; Yang, Xiaoming

    2014-01-01

    The low-emissive membrane materials have potential applications in infrared detecting technologies. Herein, we report a novel LDHs film with low infrared emissivity, which was based on the deposition of the exfoliated LDH nanosheets. The monodispersed hexagonal plate-like particles of Ni–In–CO 3 2− LDHs were prepared by coprecipitation method with hydrothermal treatment under optimized conditions. In order to exfoliate the LDHs into nanosheets, acetate-intercalated Ni–In LDHs were prepared by anion-exchange of Ni–In–CO 3 2− LDHs. The as-prepared acetate-intercalated LDHs exhibited excellent delaminating behavior in water and unilamellar nanosheets were easily obtained. The resulting positive-charged nanosheets were assembled onto quartz substrates to produce the multilayer films. The infrared emissivity values of all the samples were characterized. It was found that the incorporation of Ni 2+ and In 3+ in the host layer significantly reduced the infrared emissivity value. Moreover, the value was further reduced by the fabrication of multilayer ultrathin films, which can be ascribed to the dense orderly structure and smooth surface morphology.

  2. 47nm alumina–water nanofluid flow within boundary layer formed on upper horizontal surface of paraboloid of revolution in the presence of quartic autocatalysis chemical reaction

    Directory of Open Access Journals (Sweden)

    Isaac Lare Animasaun

    2016-09-01

    Full Text Available In this article, a modified version of buoyancy-induced model is considered to investigate the flow of 47nm alumina–water nanofluid along an upper surface of horizontal paraboloid of revolution in the presence of nonlinear thermal radiation, Lorentz force and quartic autocatalysis kind of homogeneous heterogeneous chemical reaction. The case of unequal diffusion coefficients of reactant A (bulk fluid and B (high concentration of catalyst at the surface in the presence of bioconvection is considered. Governing equation suitable to unravel the thermophoresis which takes place within the boundary layer is presented. Since chemical reactant B is of higher concentration at the surface more than the concept described as cubic autocatalytic, the suitable schemes are herein described as isothermal quartic autocatalytic reaction and first order reaction. The viscosity and thermal conductivity are assumed to vary with volume fraction (ϕ and suitable models for the case 0%⩽ϕ⩽0.8% are adopted. The transformed governing equations are solved numerically using Runge–Kutta fourth order along with shooting technique (RK4SM. Good agreement is obtained between the solutions of RK4SM and MATLAB bvp5c for a limiting case. The influence of some pertinent parameters on velocity, temperature, diffusion of motile microorganism, concentration of bulk fluid and catalyst is illustrated graphically and discussed.

  3. Site directed recombination

    Science.gov (United States)

    Jurka, Jerzy W.

    1997-01-01

    Enhanced homologous recombination is obtained by employing a consensus sequence which has been found to be associated with integration of repeat sequences, such as Alu and ID. The consensus sequence or sequence having a single transition mutation determines one site of a double break which allows for high efficiency of integration at the site. By introducing single or double stranded DNA having the consensus sequence flanking region joined to a sequence of interest, one can reproducibly direct integration of the sequence of interest at one or a limited number of sites. In this way, specific sites can be identified and homologous recombination achieved at the site by employing a second flanking sequence associated with a sequence proximal to the 3'-nick.

  4. The effect of aerobic corrosion on anaerobically-formed sulfide layers on carbon steel in dilute near-neutral pH saline solutions

    International Nuclear Information System (INIS)

    Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

    2013-01-01

    Highlights: •The corrosion rate is low when steel is exposed to anaerobic conditions (pH = 8.9). •An anaerobic corrosion with sulfide to aerobic switch increases the corrosion rate. •Aerobic conditions leads to corrosion and oxide deposition beneath FeS. •Continual air exposure leads to the blistering of the original FeS film. -- Abstract: The aerobic corrosion of pipeline steel was investigated in an aqueous sulfide solution by monitoring the corrosion potential and periodically measuring the polarization resistance. The properties and composition of the corrosion product deposits formed were determined using scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. The establishment of aerobic conditions leads to corrosion and (oxyhydr)oxide deposition beneath the anaerobically-formed mackinawite film originally present on the steel surface. This leads to blistering and spalling of the sulfide film. Chemical conversion of the mackinawite to Fe(III) (oxyhydr)oxides also occurs but is a relatively slow reaction

  5. Buried oxide layer in silicon

    Science.gov (United States)

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  6. Nonradiative recombination in semiconductors

    CERN Document Server

    Abakumov, VN; Yassievich, IN

    1991-01-01

    In recent years, great progress has been made in the understandingof recombination processes controlling the number of excessfree carriers in semiconductors under nonequilibrium conditions. As a result, it is now possible to give a comprehensivetheoretical description of these processes. The authors haveselected a number of experimental results which elucidate theunderlying physical problems and enable a test of theoreticalmodels. The following topics are dealt with: phenomenological theory ofrecombination, theoretical models of shallow and deep localizedstates, cascade model of carrier captu

  7. Recombination epoch revisited

    International Nuclear Information System (INIS)

    Krolik, J.H.

    1989-01-01

    Previous studies of cosmological recombination have shown that this process produces as a by-product a highly superthermal population of Ly-alpha photons which retard completion of recombination. Cosmological redshifting was thought to determine the frequency distribution of the photons, while two-photon decay of hydrogen's 2s state was thought to control their numbers. It is shown here that frequency diffusion due to photon scattering dominate the cosmological redshift in the frequency range near line center which fixes the ratio of ground state to excited state population, while incoherent scattering into the far-red damping wing effectively destroys Ly-alpha photons as a rate which is competitive with two-photon decay. The former effect tends to hold back recombination, while the latter tends to accelerate it; the net results depends on cosmological parameters, particularly the combination Omega(b) h/sq rt (2q0), where Omega(b) is the fraction of the critical density provided by baryons. 18 references

  8. In vitro V(D)J recombination: signal joint formation.

    Science.gov (United States)

    Cortes, P; Weis-Garcia, F; Misulovin, Z; Nussenzweig, A; Lai, J S; Li, G; Nussenzweig, M C; Baltimore, D

    1996-11-26

    The first step of V(D)J recombination, specific cleavage at the recombination signal sequence (RSS), can be carried out by the recombination activating proteins RAG1 and RAG2. In vivo, the cleaved coding and signal ends must be rejoined to generate functional antigen receptors and maintain chromosomal integrity. We have investigated signal joint formation using deletion and inversion substrates in a cell free system. RAG1 and RAG2 alone or in combination were unable to generate signal joints. However, RAG1 and RAG2 complemented with nuclear extracts were able to recombine an extrachromosomal substrate and form precise signal joints. The in vitro reaction resembled authentic V(D)J recombination in being Ku-antigen-dependent.

  9. Forming of nanocrystal silicon films by implantation of high dose of H+ in layers of silicon on isolator and following fast thermal annealing

    International Nuclear Information System (INIS)

    Tyschenko, I.E.; Popov, V.P.; Talochkin, A.B.; Gutakovskij, A.K.; Zhuravlev, K.S.

    2004-01-01

    Formation of nanocrystalline silicon films during rapid thermal annealing of the high-dose H + ion implanted silicon-on-insulator structures was studied. It was found, that Si nanocrystals had formed alter annealings at 300-400 deg C, their formation being strongly limited by the hydrogen content in silicon and also by the annealing time. It was supposed that the nucleation of crystalline phase occurred inside the silicon islands between micropores. It is conditioned by ordering Si-Si bonds as hydrogen atoms are leaving their sites in silicon network. No coalescence of micropores takes place during the rapid thermal annealing at the temperatures up to ∼ 900 deg C. Green-orange photoluminescence was observed on synthesized films at room temperature [ru

  10. Simultaneous determination of atorvastatin calcium and ramipril in capsule dosage forms by high-performance liquid chromatography and high-performance thin layer chromatography.

    Science.gov (United States)

    Panchal, Hiral J; Suhagia, Bhanubhai N

    2010-01-01

    Two simple and accurate methods to determine atorvastatin calcium and ramipril in capsule dosage forms were developed and validated using HPLC and HPTLC. The HPLC separation was achieved on a Phenomenex Luna C18 column (250 x 4.6 mm id, 5 microm) in the isocratic mode using 0.1% phosphoric acid-acetonitrile (38 + 62, v/v), pH 3.5 +/- 0.05, mobile phase at a flow rate of 1 ml/min. The retention times were 6.42 and 2.86 min for atorvastatin calcium and ramipril, respectively. Quantification was achieved with a photodiode array detector set at 210 nm over the concentration range of 0.5-5 microg/mL for each, with mean recoveries (at three concentration levels) of 100.06 +/- 0.49% and 99.95 +/- 0.63% RSD for atorvastatin calcium and ramipril, respectively. The HPTLC separation was achieved on silica gel 60 F254 HPTLC plates using methanol-benzene-glacial acetic acid (19.6 + 80.0 + 0.4, v/v/v) as the mobile phase. The Rf values were 0.40 and 0.20 for atorvastatin calcium and ramipril, respectively. Quantification was achieved with UV densitometry at 210 nm over the concentration range of 50-500 ng/spot for each, with mean recoveries (at three concentration levels) of 99.98 +/- 0.75% and 99.87 +/- 0.83% RSD for atorvastatin calcium and ramipril, respectively. Both methods were validated according to International Conference on Harmonization guidelines and found to be simple, specific, accurate, precise, and robust. The mean assay percentages for atorvastatin calcium and ramipril were 99.90 and 99.55% for HPLC and 99.91 and 99.47% for HPTLC, respectively. The methods were successfully applied for the determination of atorvastatin calcium and ramipril in capsule dosage forms without any interference from common excipients.

  11. INTERACTION OF RECOMBINANT DIPHTHERIA TOXOIDS WITH CELLULAR RECEPTORS in vitro

    Directory of Open Access Journals (Sweden)

    K. Yu. Manoilov

    2016-06-01

    Full Text Available The aim of the research was to compare in vitro characteristics of reception of the natural diphtheria toxin — DT and its nontoxic recombinant analogs — toxoids. For assessing ligand-receptor interaction the method of immunoenzyme analysis and ELISA was used, where the bonding layer recombinant analogues of diphtheria toxin cell receptor HB-EGF from sensitive and resistant to the toxin of the organisms were served. According to the results of ELISA the natural diphtheria toxin, in contrast to recombinant toxoids — CRM197, and B subunit, interacted with mouse HB-EGF with a very low affinity. While human HB-EGF with an equally high affinity connected as toxoids as native diphtheria toxin. Therefore, the analyzed recombinant analogs of toxin obtained in E. coli cells did not reproduce in full measure the receptor specificity of the natural toxin, which should be considered in the case of using these proteins as biotech products.

  12. Experimental biodistribution studies of 99mTc-recombinant human serum albumin (rHSA): a new generation of radiopharmaceutical

    International Nuclear Information System (INIS)

    Perkins, A.C.; Frier, M.

    1994-01-01

    Recombinant human serum albumin (rHSA) produced by cultured fermentation has been prepared in the form of microcapsules nominally 3-5 μm in diameter and radiolabelled with technetium-99m following reduction with stannous chloride. Radiochemical purity was assessed by chromatography on instant thin-layer chromatography and found to be greater than 90%. No evidence of aggregation was seen by microscopic examination. Imaging biodistribution studies in New Zealand white rabbits demonstrated targeting to the liver or lung, respectively, depending upon the size and surfactant properties of the microcapsules. This communication is the first to show scintigraphic studies using 99m Tc-labelled rHSA with the potential for lung, liver and cardiovascular imaging and demonstrates that recombinant DNA technology offers an important new source of materials suitable for use as radiopharmaceuticals without the need for pooled human blood products. (orig.)

  13. The Role of Iron In Sporadic E Layers

    Science.gov (United States)

    Vondrak, T.; Woodcock, K. R. I.; Plane, J. M. C.

    Sporadic E layers in the lower thermosphere are mostly composed of metallic ions, of which Fe+ is the most abundant. Because dielectric recombination (Fe+ + elec- tron) is very slow, the lifetime of Fe+ above about 100 km is at least several days. However, below this height molecular ions such as FeO+, FeO2+ and FeN2+ form in- creasingly rapidly through reactions with O3, O2 and N2, respectively. These undergo rapid dissociative recombination with electrons, causing Fe+ to be neutralised increas- ingly rapidly as a sporadic E layer descends. Indeed, this is the most likely mechanism for the formation of the sporadic neutral Fe layers that are observed by lidar. However, atomic O plays a very important role in reducing these molecular ions back to Fe+, competing with dissociative recombination and thus slowing the rate at which Fe+ is neutralised and a sporadic E layer dissipates. This paper will discuss a laboratory and modelling study of the reactions of FeO+, FeO2+ and FeN2+ with atomic O. These reactions were studied (for the first time) in a fast flow tube, using the pulsed laser ablation of a rotating iron rod as the source of Fe+ ions in the upstream section of the tube. Reactants were then added to produce molecular ions, and atomic O further downstream through a movable injector. Fe+ and the molecular ions were detected at the downstream end of the tube using a two-stage quadrupole mass spectrometer. The spectroscopy of the FeO+ ion, observed by laser induced fluorescence, will also be discussed as a candidate for future ground-based lidar studies of the ion chemistry of the lower thermosphere.

  14. Characterization of oxide film layers formed on A106 B carbon steel in simulated secondary coolant conditions of nuclear power plants

    International Nuclear Information System (INIS)

    Strack, M.; Bordoni, R.; Chocron, M.; Olmedo, A.M.; Zampieri, G.

    2011-01-01

    The water chemistry of the secondary coolant in the majority Nuclear Power Plants is controlled by AVT (All Volatile Treatment) procedure, wherein volatile amines are use to maintain the alkaline pH required for minimizing the corrosion of structural materials which one of them is Carbon Steel. In this procedure: hydrazine, morpholine and ethanolamine are used commonly as conditioning reagents. In this context, experiments were carried out by exposing carbon steel A106 B samples in a simulated secondary coolant in order to study the nature of the oxide films. The tests were performed in a static autoclave at 260 ºC using two media: 1) Hydrazine + morpholine and 2) Hydrazine + ethanolamine during different exposure periods up to ≈1020 h. The composition, surface morphology, X-ray diffraction, a chemical descaling procedure were used- XPS, was also employed, to analyze the films grown during ≈1020 h in both media. The characterization showed that magnetite was the main corrosion product formed in the films grown in the two media. The material weight loss (W) could be fitted by a law of the type W = k t n , up to 1020 h of exposure, resulting in n =0,42, k = 6,24 for films grown in medium 1) and n = 0,39, k =6,08 for films grown in medium 2); where W is in mg/d m 2 and t in h. (author) [es

  15. The cation-deficient Ruddlesden-Popper oxysulfide Y2Ti2O5S2 as a layered sulfide: topotactic potassium intercalation to form KY2Ti2O5S2.

    Science.gov (United States)

    Rutt, Oliver J; Hill, Timothy L; Gál, Zoltán A; Hayward, Michael A; Clarke, Simon J

    2003-12-01

    Potassium intercalation into the cation-deficient n = 2 Ruddlesden-Popper oxysulfide Y(2)Ti(2)O(5)S(2) to form KY(2)Ti(2)O(5)S(2) has been carried out by reaction of the oxysulfide with potassium vapor in sealed metal tubes at 400 degrees C, potassium naphthalide in THF at 50 degrees C, or potassium in liquid ammonia at temperatures as low as -78 degrees C. Insertion of potassium is topotactic, and although a site 12-coordinate by oxide ions is vacant in the perovskite-type oxide slabs of the structure, potassium is too large to enter this site via the 4-coordinate window, and instead enters the rock-salt-type sulfide layers of the structure which necessitates a 30% increase in the lattice parameter c normal to the layers. In contrast with one of the sodium intercalates of Y(2)Ti(2)O(5)S(2) (beta-NaY(2)Ti(2)O(5)S(2)) in which sodium occupies a tetrahedral site in the sulfide layers, potassium favors an 8-coordinate site which necessitates a relative translation of adjacent oxide slabs. KY(2)Ti(2)O(5)S(2) is tetragonal: P4/mmm, a = 3.71563(4) A, c = 14.8682(2) A (at 298 K), Z = 1. Although the resistivity (3.4(1) x 10(3) Omega cm) is larger than would be expected for a metal, temperature independent paramagnetism dominates the magnetic susceptibility, and the material is electronically very similar to the analogous sodium intercalate beta-NaY(2)Ti(2)O(5)S(2) which features reduced-titanium-containing oxide layers of very similar geometry and electron count.

  16. Recombination-Driven Genome Evolution and Stability of Bacterial Species.

    Science.gov (United States)

    Dixit, Purushottam D; Pang, Tin Yau; Maslov, Sergei

    2017-09-01

    While bacteria divide clonally, horizontal gene transfer followed by homologous recombination is now recognized as an important contributor to their evolution. However, the details of how the competition between clonality and recombination shapes genome diversity remains poorly understood. Using a computational model, we find two principal regimes in bacterial evolution and identify two composite parameters that dictate the evolutionary fate of bacterial species. In the divergent regime, characterized by either a low recombination frequency or strict barriers to recombination, cohesion due to recombination is not sufficient to overcome the mutational drift. As a consequence, the divergence between pairs of genomes in the population steadily increases in the course of their evolution. The species lacks genetic coherence with sexually isolated clonal subpopulations continuously formed and dissolved. In contrast, in the metastable regime, characterized by a high recombination frequency combined with low barriers to recombination, genomes continuously recombine with the rest of the population. The population remains genetically cohesive and temporally stable. Notably, the transition between these two regimes can be affected by relatively small changes in evolutionary parameters. Using the Multi Locus Sequence Typing (MLST) data, we classify a number of bacterial species to be either the divergent or the metastable type. Generalizations of our framework to include selection, ecologically structured populations, and horizontal gene transfer of nonhomologous regions are discussed as well. Copyright © 2017 by the Genetics Society of America.

  17. Improved photovoltaic performance and stability of quantum dot sensitized solar cells using Mn-ZnSe shell structure with enhanced light absorption and recombination control.

    Science.gov (United States)

    Gopi, Chandu V V M; Venkata-Haritha, M; Kim, Soo-Kyoung; Kim, Hee-Je

    2015-08-07

    To make quantum-dot-sensitized solar cells (QDSSCs) competitive, photovoltaic parameters comparable to those of other emerging solar cell technologies are necessary. In the present study, ZnSe was used as an alternative to ZnS, one of the most widely used passivation materials in QDSSCs. ZnSe was deposited on a TiO2-CdS-CdSe photoanode to form a core-shell structure, which was more efficient in terms of reducing the electron recombination in QDSSCs. The development of an efficient passivation layer is a requirement for preventing recombination processes in order to attain high-performance and stable QDSSCs. A layer of inorganic Mn-ZnSe was applied to a QD-sensitized photoanode to enhance the adsorption and strongly inhibit interfacial recombination processes in QDSSCs, which greatly improved the power conversion efficiency. Impedance spectroscopy revealed that the combined Mn doping with ZnSe treatment reduces interfacial recombination and increases charge collection efficiency compared with Mn-ZnS, ZnS, and ZnSe. A solar cell based on the CdS-CdSe-Mn-ZnSe photoanode yielded excellent performance with a solar power conversion efficiency of 5.67%, Voc of 0.584 V, and Jsc of 17.59 mA cm(-2). Enhanced electron transport and reduced electron recombination are responsible for the improved Jsc and Voc of the QDSSCs. The effective electron lifetime of the device with Mn-ZnSe was higher than those with Mn-ZnS, ZnSe, and ZnS, leading to more efficient electron-hole separation and slower electron recombination.

  18. Recombinant Amphiphilic Protein Micelles for Drug Delivery

    OpenAIRE

    Kim, Wookhyun; Xiao, Jiantao; Chaikof, Elliot L.

    2011-01-01

    Amphiphilic block polypeptides can self-assemble into a range of nanostructures in solution, including micelles and vesicles. Our group has recently described the capacity of recombinant amphiphilic diblock copolypeptides to form highly stable micelles. In this report, we demonstrate the utility of protein nanoparticles to serve as a vehicle for controlled drug delivery. Drug-loaded micelles were produced by encapsulating dipyridamole as a model hydrophobic drug with anti-inflammatory activit...

  19. Small angle X-ray scattering and transmission electron microscopy study of the Lactobacillus brevis S-layer protein

    Energy Technology Data Exchange (ETDEWEB)

    Jaeaeskelaeinen, Pentti [Department of Biomedical Engineering and Computational Science, PO Box 2200, FI-02015 Aalto University School of Science and Technology (Finland); Engelhardt, Peter [Haartman Institute, Department of Pathology, PO Box 21, FIN-00014 University of Helsinki (Finland); Hynoenen, Ulla; Palva, Airi [Department of Basic Veterinary Sciences, Division of Microbiology, FIN-00014 University of Helsinki (Finland); Torkkeli, Mika; Serimaa, Ritva, E-mail: ritva.serimaa@helsinki.f [Department of Physics, POB 64, 00014 University of Helsinki (Finland)

    2010-10-01

    The structure of self-assembly domain containing recombinant truncation mutants of Lactobacillus brevis surface layer protein SlpA in aqueous solution was studied using small-angle X-ray scattering and transmission electron microscopy. The proteins were found out to interact with each other forming stable globular oligomers of about 10 monomers. The maximum diameter of the oligomers varied between 75 A and 435 A.

  20. Meiotic recombination hotspots - a comparative view.

    Science.gov (United States)

    Choi, Kyuha; Henderson, Ian R

    2015-07-01

    During meiosis homologous chromosomes pair and undergo reciprocal genetic exchange, termed crossover. Meiotic recombination has a profound effect on patterns of genetic variation and is an important tool during crop breeding. Crossovers initiate from programmed DNA double-stranded breaks that are processed to form single-stranded DNA, which can invade a homologous chromosome. Strand invasion events mature into double Holliday junctions that can be resolved as crossovers. Extensive variation in the frequency of meiotic recombination occurs along chromosomes and is typically focused in narrow hotspots, observed both at the level of DNA breaks and final crossovers. We review methodologies to profile hotspots at different steps of the meiotic recombination pathway that have been used in different eukaryote species. We then discuss what these studies have revealed concerning specification of hotspot locations and activity and the contributions of both genetic and epigenetic factors. Understanding hotspots is important for interpreting patterns of genetic variation in populations and how eukaryotic genomes evolve. In addition, manipulation of hotspots will allow us to accelerate crop breeding, where meiotic recombination distributions can be limiting. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  1. Recombinant Collagenlike Proteins

    Science.gov (United States)

    Fertala, Andzej

    2007-01-01

    A group of collagenlike recombinant proteins containing high densities of biologically active sites has been invented. The method used to express these proteins is similar to a method of expressing recombinant procollagens and collagens described in U. S. Patent 5,593,859, "Synthesis of human procollagens and collagens in recombinant DNA systems." Customized collagenous proteins are needed for biomedical applications. In particular, fibrillar collagens are attractive for production of matrices needed for tissue engineering and drug delivery. Prior to this invention, there was no way of producing customized collagenous proteins for these and other applications. Heretofore, collagenous proteins have been produced by use of such biological systems as yeasts, bacteria, and transgenic animals and plants. These products are normal collagens that can also be extracted from such sources as tendons, bones, and hides. These products cannot be made to consist only of biologically active, specific amino acid sequences that may be needed for specific applications. Prior to this invention, it had been established that fibrillar collagens consist of domains that are responsible for such processes as interaction with cells, binding of growth factors, and interaction with a number of structural proteins present in the extracellular matrix. A normal collagen consists of a sequence of domains that can be represented by a corresponding sequence of labels, e.g., D1D2D3D4. A collagenlike protein of the present invention contains regions of collagen II that contain multiples of a single domain (e.g., D1D1D1D1 or D4D4D4D4) chosen for its specific biological activity. By virtue of the multiplicity of the chosen domain, the density of sites having that specific biological activity is greater than it is in a normal collagen. A collagenlike protein according to this invention can thus be made to have properties that are necessary for tissue engineering.

  2. Impact of electrically formed interfacial layer and improved memory characteristics of IrOx/high-κx/W structures containing AlOx, GdOx, HfOx, and TaOx switching materials.

    Science.gov (United States)

    Prakash, Amit; Maikap, Siddheswar; Banerjee, Writam; Jana, Debanjan; Lai, Chao-Sung

    2013-09-06

    Improved switching characteristics were obtained from high-κ oxides AlOx, GdOx, HfOx, and TaOx in IrOx/high-κx/W structures because of a layer that formed at the IrOx/high-κx interface under external positive bias. The surface roughness and morphology of the bottom electrode in these devices were observed by atomic force microscopy. Device size was investigated using high-resolution transmission electron microscopy. More than 100 repeatable consecutive switching cycles were observed for positive-formatted memory devices compared with that of the negative-formatted devices (only five unstable cycles) because it contained an electrically formed interfacial layer that controlled 'SET/RESET' current overshoot. This phenomenon was independent of the switching material in the device. The electrically formed oxygen-rich interfacial layer at the IrOx/high-κx interface improved switching in both via-hole and cross-point structures. The switching mechanism was attributed to filamentary conduction and oxygen ion migration. Using the positive-formatted design approach, cross-point memory in an IrOx/AlOx/W structure was fabricated. This cross-point memory exhibited forming-free, uniform switching for >1,000 consecutive dc cycles with a small voltage/current operation of ±2 V/200 μA and high yield of >95% switchable with a large resistance ratio of >100. These properties make this cross-point memory particularly promising for high-density applications. Furthermore, this memory device also showed multilevel capability with a switching current as low as 10 μA and a RESET current of 137 μA, good pulse read endurance of each level (>105 cycles), and data retention of >104 s at a low current compliance of 50 μA at 85°C. Our improvement of the switching characteristics of this resistive memory device will aid in the design of memory stacks for practical applications.

  3. The role of recombination in the emergence of a complex and dynamic HIV epidemic

    Directory of Open Access Journals (Sweden)

    Morgenstern Burkhard

    2010-03-01

    Full Text Available Abstract Background Inter-subtype recombinants dominate the HIV epidemics in three geographical regions. To better understand the role of HIV recombinants in shaping the current HIV epidemic, we here present the results of a large-scale subtyping analysis of 9435 HIV-1 sequences that involve subtypes A, B, C, G, F and the epidemiologically important recombinants derived from three continents. Results The circulating recombinant form CRF02_AG, common in West Central Africa, appears to result from recombination events that occurred early in the divergence between subtypes A and G, followed by additional recent recombination events that contribute to the breakpoint pattern defining the current recombinant lineage. This finding also corrects a recent claim that G is a recombinant and a descendant of CRF02, which was suggested to be a pure subtype. The BC and BF recombinants in China and South America, respectively, are derived from recent recombination between contemporary parental lineages. Shared breakpoints in South America BF recombinants indicate that the HIV-1 epidemics in Argentina and Brazil are not independent. Therefore, the contemporary HIV-1 epidemic has recombinant lineages of both ancient and more recent origins. Conclusions Taken together, we show that these recombinant lineages, which are highly prevalent in the current HIV epidemic, are a mixture of ancient and recent recombination. The HIV pandemic is moving towards having increasing complexity and higher prevalence of recombinant forms, sometimes existing as "families" of related forms. We find that the classification of some CRF designations need to be revised as a consequence of (1 an estimated > 5% error in the original subtype assignments deposited in the Los Alamos sequence database; (2 an increasing number of CRFs are defined while they do not readily fit into groupings for molecular epidemiology and vaccine design; and (3 a dynamic HIV epidemic context.

  4. Recombinant Innovation and Endogenous Transitions

    OpenAIRE

    Koen Frenken; Luis R. Izquierdo; Paolo Zeppini

    2012-01-01

    We propose a model of technological transitions based on two different types of innovations. Branching innovations refer to technological improvements along a particular path, while recombinant innovations represent fusions of multiple paths. Recombinant innovations create “short-cuts” which reduce switching costs allowing agents to escape a technological lock-in. As a result, recombinant innovations speed up technological progress allowing transitions that are impossible with only branching ...

  5. Expression and Purification of Active Recombinant Cathepsin C (Dipeptidyl Aminopeptidase I of Kuruma Prawn Marsupenaeus japonicus in Insect Cells

    Directory of Open Access Journals (Sweden)

    Gao-Feng Qiu

    2009-01-01

    Full Text Available Cathepsin C (CTSC is a lysosomal cysteine protease belonging to the papain superfamily. Our previous study showed that CTSC precursor (zymogen is localized exclusively in cortical rods (CRs of mature oocyte in the kuruma prawn Marsupenaeus japonicus, suggesting that CTSC might have roles on regulating release and/or formation of a jelly layer. In this study, enzymically active CTSC of the kuruma prawn was prepared by recombinant expression in the High Five insect cell line. The recombinant enzyme with a polyhistidine tag at its C-terminus was considered to be initially secreted into the culture medium as an inactive form of zymogen, because Western blot with anti-CTSC antibody detected a 51 kDa protein corresponding to CTSC precursor. After purification by affinity chromatography on nickel-iminodiacetic acid resin, the enzyme displayed three forms of 51, 31, and 30 kDa polypeptides. All of the forms can be recognized by antiserum raised against C-terminal polyhistidine tag, indicating that the 31 and 30 kDa forms were generated from 51 kDa polypeptide by removal of a portion of the N-terminus of propeptide. Following activation at pH 5.5 and 37∘C for 40 hours under native conditions, the recombinant CTSC (rCTSC exhibited increased activity against the synthetic substrate Gly-Phe-β-naphthylamide and optimal pH at around 5. The purified rCTSC will be useful for further characterization of its exact physiological role on CRs release and/or formation of a jelly layer in kuruma prawn.

  6. Genetic recombination in auxotrophic strains of Phanerochaete chrysosporium

    International Nuclear Information System (INIS)

    Krejci, R.

    1987-01-01

    Four auxotrophic strains of ligninolytic basidiomycete Phanerochaete chrysosporium were obtained by UV mutagenesis. The heterokaryotic mycelium formed by complementation of different auxotrophic isolates was able to fruit and produce basidiospores. Prototrophic strains and strains with a recombined set of parental nutritional requirements were isolated from the basidiospore progeny of the heterokaryons. Genetic recombination hence takes place in fruit bodies produced by the heterokaryotic mycelium. (author). 3 tabs., 13 refs

  7. Improved electron transport layer

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides: a method of preparing a coating ink for forming a zinc oxide electron transport layer, comprising mixing zinc acetate and a wetting agent in water or methanol; a coating ink comprising zinc acetate and a wetting agent in aqueous solution or methanolic solution......; a method of preparing a zinc oxide electron transporting layer, which method comprises: i) coating a substrate with the coating ink of the present invention to form a film; ii) drying the film; and iii) heating the dry film to convert the zinc acetate substantially to ZnO; a method of preparing an organic...... photovoltaic device or an organic LED having a zinc oxide electron transport layer, the method comprising, in this order: a) providing a substrate bearing a first electrode layer; b) forming an electron transport layer according to the following method: i) coating a coating ink comprising an ink according...

  8. Expression of recombinant Antibodies

    Directory of Open Access Journals (Sweden)

    André eFrenzel

    2013-07-01

    Full Text Available Recombinant antibodies are highly specific detection probes in research, diagnostics and have emerged over the last two decades as the fastest growing class of therapeutic proteins. Antibody generation has been dramatically accelerated by in vitro selection systems, particularly phage display. An increasing variety of recombinant production systems have been developed, ranging from Gram-negative and positive bacteria, yeasts and filamentous fungi, insect cell lines, mammalian cells to transgenic plants and animals. Currently, almost all therapeutic antibodies are still produced in mammalian cell lines in order to reduce the risk of immunogenicity due to altered, non-human glycosylation patterns. However, recent developments of glycosylation-engineered yeast, insect cell lines and transgenic plants are promising to obtain antibodies with human-like post-translational modifications. Furthermore, smaller antibody fragments including bispecific antibodies without any glycosylation are successfully produced in bacteria and have advanced to clinical testing. The first therapeutic antibody products from a non-mammalian source can be expected in coming next years. In this review, we focus on current antibody production systems including their usability for different applications.

  9. Recombination and photosensitivity centres in boron nitride irradiated with ions

    International Nuclear Information System (INIS)

    Kabyshev, A.; Konusov, F.; Lopatin, V.

    2001-01-01

    The physical-chemical processes, taking place during the irradiation of dielectrics with ions distort the electron structure of the compounds and generate additional localise state in the forbidden zone (FZ). Consequently, the semiconductor layer with the specific surface density of σ ≥ 10 -10 S/ forms on the surface of the dielectric. In addition to his, the high concentration of the radiation-induced defects changes the optical and photoelectric properties of the materials and also the energy characteristics. Analysis of the photoelectric properties indicates that the recombination processes take part in electric transport. These processes restricted the increase of the photosensitivity and changing the kinetics of relaxation of photo conductivity (σ hv ). The practical application of the boron nitride (BN) the in the thermonuclear systems (for example, Ref. 7), stimulates research into the reasons for the deceleration of its properties under the effect of radiation of various types. The conductivity of non-irradiated boron nitride is of the electron-hole nature with a large fraction of the activation component in exchange of the charge carriers between the levels of the defects and the forbidden zones. On the basis of the correlation of the energy and kinetic parameters of luminescence and , the authors of Ref. 8 constructed a model of electron transfers accompanying the electric transport of the boron nitride. In addition to ion-thermal modification, the conductivity of boron nitride is also of the electron-hole nature and is accompanied by luminescence. Examination of the characteristics of luminescence may be useful for obtaining more information on the transport mechanism. In this work, in order to clarify the main parameters of the forbidden band, detailed investigations were carried out into the spectrum of the electronic states of radiation defects which determine the photoelectric and luminescence properties of the modified boron nitride. The

  10. On the relict recombination lines

    International Nuclear Information System (INIS)

    Bershtejn, I.N.; Bernshtejn, D.N.; Dubrovich, V.K.

    1977-01-01

    Accurate numerical calculation of intensities and profiles of hydrogen recombination lines of cosmological origin is made. Relie radiation distortions stipulated by recombination quantum release at the irrevocable recombination are investigated. Mean number calculation is given for guantums educing for one irrevocably-lost electron. The account is taken of the educed quantums interraction with matter. The main quantum-matter interrraction mechanisms are considered: electronic blow broadening; free-free, free-bound, bound-bound absorptions Recombination dynamics is investigated depending on hydrogen density and total density of all the matter kinds in the Universe

  11. Two layer powder pressing

    International Nuclear Information System (INIS)

    Schreiner, H.

    1979-01-01

    First, significance and advantages of sintered materials consisting of two layers are pointed out. By means of the two layer powder pressing technique metal powders are formed resulting in compacts with high accuracy of shape and mass. Attributes of basic powders, different filling methods and pressing techniques are discussed. The described technique is supposed to find further applications in the field of two layer compacts in the near future

  12. Reduced recombination in a surface-sulfurized Cu(InGa)Se2 thin-film solar cell

    Science.gov (United States)

    Kim, Shinho; Nishinaga, Jiro; Kamikawa, Yukiko; Ishizuka, Shogo; Nagai, Takehiko; Koida, Takashi; Tampo, Hitoshi; Shibata, Hajime; Matsubara, Koji; Niki, Shigeru

    2018-05-01

    This study demonstrates surface sulfurization effects on Cu(InGa)Se2 (CIGSe) thin-film solar cells with a single back-graded band gap. Single back-graded CIGSe thin films were prepared via a three-stage process in a high-vacuum molecular beam epitaxial growth chamber and were subsequently annealed in a tube furnace under environmental conditions with H2S gas. After sulfurization, an ∼80- to ∼100-nm-thick CuIn(SSe)2 layer with significantly small Ga contents (CISSe:Ga) was formed on the CIGSe layer. The newly formed CISSe:Ga layer exhibited graded S contents from surface to bulk, thus resulting in a front-graded band gap. In addition, CISSe:Ga was covered with S-enriched CISSe region that was extended from the surface to a depth of a few nm and was depleted of Ga. A device with the sulfurized CIGSe showed reduced recombination at the buffer–absorber interface, in space-charge region and in bulk. Consequently, the open circuit voltage increased from 0.58 V (in the non-sulfurized case) to 0.66 V, and the conversion efficiency improved from 15.5 to 19.4%. This large improvement is caused by the front graded band gap at the surface and the hole-blocking barrier, which suppress recombination at the CdS/CISSe:Ga interface. In addition, sulfurization followed by KF post-deposition treatment (PDT) increased the efficiency to 20.1%. Compared to the untreated sulfurized device, the KF-PDT device delivered an increased carrier lifetime and reduced the recombination in bulk probably because the defects were passivated by the K, which penetrated into the bulk region.

  13. Subnanometer Ga 2 O 3 Tunnelling Layer by Atomic Layer Deposition to Achieve 1.1 V Open-Circuit Potential in Dye-Sensitized Solar Cells

    KAUST Repository

    Chandiran, Aravind Kumar; Tetreault, Nicolas; Humphry-Baker, Robin; Kessler, Florian; Baranoff, Etienne; Yi, Chenyi; Nazeeruddin, Mohammad Khaja; Grä tzel, Michael

    2012-01-01

    Herein, we present the first use of a gallium oxide tunnelling layer to significantly reduce electron recombination in dye-sensitized solar cells (DSC). The subnanometer coating is achieved using atomic layer deposition (ALD) and leading to a new

  14. Recombination Parameters for Antimonide-Based Semiconductors using RF Photoreflection Techniques

    International Nuclear Information System (INIS)

    Kumar, R.J.; Borrego, J.M.; Dutta, P.S.; Gutmann, R.J.; Wang, C.A.; Martinelli, R.U.; Nichols, G.

    2002-01-01

    RF photoreflection measurements and PC-1D simulations have been used to evaluate bulk and surface recombination parameters in antimonide-based materials. PC-1D is used to simulate the photoconductivity response of antimonide-based substrates and doubly-capped epitaxial layers and also to determine how to extract the recombination parameters using experimental results. Excellent agreement has been obtained with a first-order model and test structure simulation when Shockley-Reed-Hall (SRH) recombination is the bulk recombination process. When radiative, Auger and surface recombination are included, the simulation results show good agreement with the model. RF photoreflection measurements and simulations using PC-1D are compatible with a radiative recombination coefficient (B) of approximately 5 x 10 -11 cm 3 /s, Auger coefficient (C) ∼ 1.0 x 10 -28 cm 6 /s and surface recombination velocity (SRV) ∼ 600 cm/s for 0.50-0.55 eV doubly-capped InGaAsSb material with GaSb capping layers using the experimentally determined active layer doping of 2 x 10 17 cm -3 . Photon recycling, neglected in the analysis and simulations presented, will affect the extracted recombination parameters to some extent

  15. Interface Recombination in Depleted Heterojunction Photovoltaics based on Colloidal Quantum Dots

    KAUST Repository

    Kemp, Kyle W.

    2013-03-26

    Interface recombination was studied in colloidal quantum dot photovoltaics. Optimization of the TiO2 -PbS interface culminated in the introduction of a thin ZnO buffer layer deposited with atomic layer deposition. Transient photovoltage measurements indicated a nearly two-fold decrease in the recombination rate around 1 sun operating conditions. Improvement to the recombination rate led to a device architecture with superior open circuit voltage (VOC) and photocurrent extraction. Overall a 10% improvement in device efficiency was achieved with Voc enhancements up to 50 mV being realized. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Evidence for Kinetic Limitations as a Controlling Factor of Ge Pyramid Formation: a Study of Structural Features of Ge/Si(001) Wetting Layer Formed by Ge Deposition at Room Temperature Followed by Annealing at 600 °C.

    Science.gov (United States)

    Storozhevykh, Mikhail S; Arapkina, Larisa V; Yuryev, Vladimir A

    2015-12-01

    The article presents an experimental study of an issue of whether the formation of arrays of Ge quantum dots on the Si(001) surface is an equilibrium process or it is kinetically controlled. We deposited Ge on Si(001) at the room temperature and explored crystallization of the disordered Ge film as a result of annealing at 600 °C. The experiment has demonstrated that the Ge/Si(001) film formed in the conditions of an isolated system consists of the standard patched wetting layer and large droplike clusters of Ge rather than of huts or domes which appear when a film is grown in a flux of Ge atoms arriving on its surface. We conclude that the growth of the pyramids appearing at temperatures greater than 600 °C is controlled by kinetics rather than thermodynamic equilibrium whereas the wetting layer is an equilibrium structure. Primary 68.37.Ef; 68.55.Ac; 68.65.Hb; 81.07.Ta; 81.16.Dn.

  17. Dissociative recombination of dications

    International Nuclear Information System (INIS)

    Seiersen, K.; Heber, O.; Jensen, M.J.; Safvan, C.P.; Andersen, L. H.

    2003-01-01

    Dissociative recombination (DR) of doubly-charged positive ions has been studied at the heavy ion storage ring ASTRID. Low-energy electrons were scattered on the dication of the N 2 molecule, and the absolute cross section was measured in the energy range of 10 -4 -50 eV. From the measured cross section, a thermal rate coefficient of 5.8x10 -7 cm 3 s -1 at 300 K was extracted. Furthermore, we present new results on the CO 2+ DR rate, and a summary and comparison of measured DR rate coefficients for both the singly and doubly-charged ions of CO, CO 2 , and N 2 is presented

  18. Natural and recombinant fungal laccases for paper pulp bleaching

    NARCIS (Netherlands)

    Sigoillot, C.; Record, E.; Belle, V.; Robert, J.L.; Levasseur, A.; Punt, P.J.; Hondel, C.A.M.J.J. van den; Fournel, A.; Sigoillot, J.C.; Asther, M.

    2004-01-01

    Three laccases, a natural form and two recombinant forms obtained from two different expression hosts, were characterized and compared for paper pulp bleaching. Laccase from Pycnoporus cinnabarinus, a well known lignolytic fungus, was selected as a reference for this study. The corresponding

  19. Cell biology of mitotic recombination

    DEFF Research Database (Denmark)

    Lisby, Michael; Rothstein, Rodney

    2015-01-01

    Homologous recombination provides high-fidelity DNA repair throughout all domains of life. Live cell fluorescence microscopy offers the opportunity to image individual recombination events in real time providing insight into the in vivo biochemistry of the involved proteins and DNA molecules as w...

  20. Hadron Correlations and Parton Recombination

    Energy Technology Data Exchange (ETDEWEB)

    Fries, R.J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)]. E-mail: rjfries@comp.tamu.edu

    2007-02-15

    Parton recombination has been found to be an extremely useful model to understand hadron production at the Relativistic Heavy Ion Collider. It is particularly important to explore its connections with hard processes. This article reviews some of the aspects of the quark recombination model and places particular emphasis on hadron correlations.

  1. Auger recombination in sodium iodide

    Science.gov (United States)

    McAllister, Andrew; Kioupakis, Emmanouil; Åberg, Daniel; Schleife, André

    2014-03-01

    Scintillators are an important tool used to detect high energy radiation - both in the interest of national security and in medicine. However, scintillator detectors currently suffer from lower energy resolutions than expected from basic counting statistics. This has been attributed to non-proportional light yield compared to incoming radiation, but the specific mechanism for this non-proportionality has not been identified. Auger recombination is a non-radiative process that could be contributing to the non-proportionality of scintillating materials. Auger recombination comes in two types - direct and phonon-assisted. We have used first-principles calculations to study Auger recombination in sodium iodide, a well characterized scintillating material. Our findings indicate that phonon-assisted Auger recombination is stronger in sodium iodide than direct Auger recombination. Computational resources provided by LLNL and NERSC. Funding provided by NA-22.

  2. InP solar cell with window layer

    Science.gov (United States)

    Jain, Raj K. (Inventor); Landis, Geoffrey A. (Inventor)

    1994-01-01

    The invention features a thin light transmissive layer of the ternary semiconductor indium aluminum arsenide (InAlAs) as a front surface passivation or 'window' layer for p-on-n InP solar cells. The window layers of the invention effectively reduce front surface recombination of the object semiconductors thereby increasing the efficiency of the cells.

  3. Two novel porcine epidemic diarrhea virus (PEDV) recombinants from a natural recombinant and distinct subtypes of PEDV variants.

    Science.gov (United States)

    Chen, Nanhua; Li, Shuangjie; Zhou, Rongyun; Zhu, Meiqin; He, Shan; Ye, Mengxue; Huang, Yucheng; Li, Shuai; Zhu, Cong; Xia, Pengpeng; Zhu, Jianzhong

    2017-10-15

    Porcine epidemic diarrhea virus (PEDV) causes devastating impact on global pig-breeding industry and current vaccines have become not effective against the circulating PEDV variants since 2011. During the up-to-date investigation of PEDV prevalence in Fujian China 2016, PEDV was identified in vaccinated pig farms suffering severe diarrhea while other common diarrhea-associated pathogens were not detected. Complete genomes of two PEDV representatives (XM1-2 and XM2-4) were determined. Genomic comparison showed that these two viruses share the highest nucleotide identities (99.10% and 98.79%) with the 2011 ZMDZY strain, but only 96.65% and 96.50% nucleotide identities with the attenuated CV777 strain. Amino acid alignment of spike (S) proteins indicated that they have the similar mutation, insertion and deletion pattern as other Chinese PEDV variants but also contain several unique substitutions. Phylogenetic analysis showed that 2016 PEDV variants belong to the cluster of recombination strains but form a new branch. Recombination detection suggested that both XM1-2 and XM2-4 are inter-subgroup recombinants with breakpoints within ORF1b. Remarkably, the natural recombinant HNQX-3 isolate serves as a parental virus for both natural recombinants identified in this study. This up-to-date investigation provides the direct evidence that natural recombinants may serve as parental viruses to generate recombined PEDV progenies that are probably associated with the vaccination failure. Copyright © 2017. Published by Elsevier B.V.

  4. RECOMBINATION OF ANTIBODY POLYPEPTIDE CHAINS IN THE PRESENCE OF ANTIGEN

    Science.gov (United States)

    Metzger, Henry; Mannik, Mart

    1964-01-01

    Conditions were developed by which the separated H and L chains of gamma2 globulins recombined to form four-chained molecules in good yields. In the absence of antigen, anti-2,4-dinitrophenyl (anti-DNP) H chains randomly reassociated with a mixture of antibody and non-specific gamma2 globulin L chains. In the presence of a specific hapten, however, the antibody H chains preferentially interacted with the anti-DNP L chains. Antibody H chain-antibody L chain recombinants formed in the presence of hapten were more active than the corresponding recombinants formed in the absence of hapten. Speculations are made regarding the possible mechanisms and biological significance of these effects. PMID:14247718

  5. Analysis of intermolecular RNA-RNA recombination by rubella virus

    International Nuclear Information System (INIS)

    Adams, Sandra D.; Tzeng, W.-P.; Chen, M.-H.; Frey, Teryl K.

    2003-01-01

    To investigate whether rubella virus (RUB) undergoes intermolecular RNA-RNA recombination, cells were cotransfected with pairs of in vitro transcripts from genomic cDNA plasmid vectors engineered to contain nonoverlapping deletions: the replicative transcript maintained the 5'-proximal nonstructural (NS) ORF (which contained the replicase, making it RNA replication competent), had a deletion in the 3'-proximal structural protein (SP) ORF, and maintained the 3' end of the genome, including the putative 3' cis-acting elements (CSE), while the nonreplicative transcript consisted of the 3' half of the genome including the SP-ORF and 3' CSE. Cotransfection yielded plaque-forming virus that synthesized the standard genomic and subgenomic RNAs and thus was generated by RNA-RNA recombination. Using transcripts tagged with a 3'-terminal deletion, it was found that recombinants contained the 3' end derived from the replicative strand, indicating a cis-preference for initiation of negative-strand synthesis. In cotransfections in which the replicative transcript lacked the 3' CSE, recombination occurred, albeit at lower efficiency, indicating that initiation in trans from the NS-ORF can occur. The 3' CSE was sufficient as a nonreplicative transcript, showing that it can serve as a promoter for negative-strand RNA synthesis. While deletion mutagenesis showed that the presence of the junction untranslated region (J-UTR) between the ORFs appeared to be necessary on both transcripts for recombination in this region of the genome, analysis with transcripts tagged with restriction sites showed that the J-UTR was not a hot spot for recombination compared to neighboring regions in both ORFs. Sequence analysis of recombinants revealed that both precise (homologous) and imprecise recombination (aberrant, homologous resulting in duplications) occurred; however, imprecise recombination only involved the J-UTR or the 3' end of the NS-ORF and the J-UTR (maintaining the NS-ORF), indicating

  6. Photovoltaic cell module and method of forming

    Science.gov (United States)

    Howell, Malinda; Juen, Donnie; Ketola, Barry; Tomalia, Mary Kay

    2017-12-12

    A photovoltaic cell module, a photovoltaic array including at least two modules, and a method of forming the module are provided. The module includes a first outermost layer and a photovoltaic cell disposed on the first outermost layer. The module also includes a second outermost layer disposed on the photovoltaic cell and sandwiching the photovoltaic cell between the second outermost layer and the first outermost layer. The method of forming the module includes the steps of disposing the photovoltaic cell on the first outermost layer, disposing a silicone composition on the photovoltaic cell, and compressing the first outermost layer, the photovoltaic cell, and the second layer to form the photovoltaic cell module.

  7. Comparative analysis of the molecular mechanisms of recombination in hepatitis C virus

    DEFF Research Database (Denmark)

    Galli, Andrea; Bukh, Jens

    2014-01-01

    Genetic recombination is an important evolutionary mechanism for RNA viruses. The significance of this phenomenon for hepatitis C virus (HCV) has recently become evident, with the identification of circulating recombinant forms in HCV-infected individuals and by novel data from studies permitted...... by advances in HCV cell culture systems and genotyping protocols. HCV is readily able to produce viable recombinants, using replicative and non-replicative molecular mechanisms. However, our knowledge of the required molecular mechanisms remains limited. Understanding how HCV recombines might be instrumental...... for a better monitoring of global epidemiology, to clarify the virus evolution, and evaluate the impact of recombinant forms on the efficacy of oncoming combination drug therapies. For the latter, frequency and location of recombination events could affect the efficacy of multidrug regimens. This review...

  8. Light illumination intensity dependence of photovoltaic parameter in polymer solar cells with ammonium heptamolybdate as hole extraction layer.

    Science.gov (United States)

    Liu, Zhiyong; Niu, Shengli; Wang, Ning

    2018-01-01

    A low-temperature, solution-processed molybdenum oxide (MoO X ) layer and a facile method for polymer solar cells (PSCs) is developed. The PSCs based on a MoO X layer as the hole extraction layer (HEL) is a significant advance for achieving higher photovoltaic performance, especially under weaker light illumination intensity. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements show that the (NH 4 ) 6 Mo 7 O 24 molecule decomposes and forms the molybdenum oxide (MoO X ) molecule when undergoing thermal annealing treatment. In this study, PSCs with the MoO X layer as the HEL exhibited better photovoltaic performance, especially under weak light illumination intensity (from 100 to 10mWcm -2 ) compared to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)-based PSCs. Analysis of the current density-voltage (J-V) characteristics at various light intensities provides information on the different recombination mechanisms in the PSCs with a MoO X and PEDOT:PSS layer as the HEL. That the slopes of the open-circuit voltage (V OC ) versus light illumination intensity plots are close to 1 unity (kT/q) reveals that bimolecular recombination is the dominant and weaker monomolecular recombination mechanism in open-circuit conditions. That the slopes of the short-circuit current density (J SC ) versus light illumination intensity plots are close to 1 reveals that the effective charge carrier transport and collection mechanism of the MoO X /indium tin oxide (ITO) anode is the weaker bimolecular recombination in short-circuit conditions. Our results indicate that MoO X is an alternative candidate for high-performance PSCs, especially under weak light illumination intensity. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Basis reduction for layered lattices

    NARCIS (Netherlands)

    E.L. Torreão Dassen (Erwin)

    2011-01-01

    htmlabstractWe develop the theory of layered Euclidean spaces and layered lattices. With this new theory certain problems that usually are solved by using classical lattices with a "weighting" gain a new, more natural form. Using the layered lattice basis reduction algorithms introduced here these

  10. Oxygen-hydrogen recombination system

    International Nuclear Information System (INIS)

    Sato, Shuichiro; Takejima, Masaki.

    1981-01-01

    Purpose: To avoid reduction in the performance of catalyst used for an oxygen-hydrogen recombiner in the off gas processing system of a nuclear reactor. Constitution: A thermometer is provided for the detection of temperature in an oxygen-hydrogen recombiner. A cooling pipe is provided in the recombiner and cooling medium is introduced externally. The cooling medium may be water or air. In accordance with the detection value from the thermometer, ON-OFF control is carried out for a valve to control the flow rate of the cooling medium thereby rendering the temperature in the recombiner to a predetermined value. This can prevent the catalyst from being exposed to high temperature and avoid the reduction in the performance of the catalyst. (Ikeda, J.)

  11. Controlled Release from Recombinant Polymers

    Science.gov (United States)

    Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

    2014-01-01

    Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

  12. Hydrogen recombiner development at AECL

    International Nuclear Information System (INIS)

    Dewit, W.A.; Koroll, G.W.; Loesel Sitar, J.; Graham, W.R.C.

    1997-01-01

    Catalytic recombiners have been developed at AECL for the purpose of hydrogen removal in post-accident nuclear containment buildings. The recombiners are based on a particular catalyst designed by AECL which has extraordinary resistance to fouling from water and water vapour and a large thermodynamic range of operation. The catalysts were developed, originally, for the purpose of heavy water manufacturing by way of a catalytic exchange process. Application of these catalyst materials in recombiners for containment applications began in the late 1980's. The first application was a passive recombiner, qualified for use in control of radiolytic hydrogen in the headspace of a pool-type experimental reactor of AECL design in 1988. The passive, or natural convection recombiner concept has continued development to commercial stage for application in power reactor containments. This paper reviews the AECL recombiner development, describes the current model and shows results from tests of full-scale recombiners in the Large Scale Vented Combustion Test Facility at AECL-WL. The AECL recombiner is designed for compactness and ease of engineering into containment. The design is a simple, open-ended rectangular enclosure with catalyst elements arranged inside to promote optimum convective flow driven by heat of recombination at the catalyst surface. Self start, as evidenced by catalyst heating and initiation of flow, is achieved in less than 1% hydrogen, with available oxygen, at room temperature and 100% relative humidity. This low temperature start-up in condensing atmospheres is viewed as the most challenging condition for wet-proofing effectiveness. Cold start-up is a vital performance requirement in containments, such as CANDU, where engineered air-cooling systems are operating and where long-term hydrogen control is required, after containment atmospheres have cooled. Once started, the removal capacity scales linearly with the inlet cross-section area and the partial

  13. Review of Parton Recombination Models

    International Nuclear Information System (INIS)

    Bass, Steffen A

    2006-01-01

    Parton recombination models have been very successful in explaining data taken at RHIC on hadron spectra and emission patterns in Au+Au collisions at transverse momenta above 2 GeV/c, which have exhibited features which could not be understood in the framework of basic perturbative QCD. In this article I will review the current status on recombination models and outline which future challenges need to be addressed by this class of models

  14. Recombinant snake venom prothrombin activators

    OpenAIRE

    L?vgren, Ann

    2012-01-01

    Three prothrombin activators; ecarin, which was originally isolated from the venom of the saw-scaled viper Echis carinatus, trocarin from the rough-scaled snake Tropidechis carinatus, and oscutarin from the Taipan snake Oxyuranus scutellatus, were expressed in mammalian cells with the purpose to obtain recombinant prothrombin activators that could be used to convert prothrombin to thrombin. We have previously reported that recombinant ecarin can efficiently generate thrombin without the need ...

  15. The potential of shifting recombination hotspots to increase genetic gain in livestock breeding.

    Science.gov (United States)

    Gonen, Serap; Battagin, Mara; Johnston, Susan E; Gorjanc, Gregor; Hickey, John M

    2017-07-04

    This study uses simulation to explore and quantify the potential effect of shifting recombination hotspots on genetic gain in livestock breeding programs. We simulated three scenarios that differed in the locations of quantitative trait nucleotides (QTN) and recombination hotspots in the genome. In scenario 1, QTN were randomly distributed along the chromosomes and recombination was restricted to occur within specific genomic regions (i.e. recombination hotspots). In the other two scenarios, both QTN and recombination hotspots were located in specific regions, but differed in whether the QTN occurred outside of (scenario 2) or inside (scenario 3) recombination hotspots. We split each chromosome into 250, 500 or 1000 regions per chromosome of which 10% were recombination hotspots and/or contained QTN. The breeding program was run for 21 generations of selection, after which recombination hotspot regions were kept the same or were shifted to adjacent regions for a further 80 generations of selection. We evaluated the effect of shifting recombination hotspots on genetic gain, genetic variance and genic variance. Our results show that shifting recombination hotspots reduced the decline of genetic and genic variance by releasing standing allelic variation in the form of new allele combinations. This in turn resulted in larger increases in genetic gain. However, the benefit of shifting recombination hotspots for increased genetic gain was only observed when QTN were initially outside recombination hotspots. If QTN were initially inside recombination hotspots then shifting them decreased genetic gain. Shifting recombination hotspots to regions of the genome where recombination had not occurred for 21 generations of selection (i.e. recombination deserts) released more of the standing allelic variation available in each generation and thus increased genetic gain. However, whether and how much increase in genetic gain was achieved by shifting recombination hotspots depended

  16. Delayed recombination and cosmic parameters

    International Nuclear Information System (INIS)

    Galli, Silvia; Melchiorri, Alessandro; Bean, Rachel; Silk, Joseph

    2008-01-01

    Current cosmological constraints from cosmic microwave background anisotropies are typically derived assuming a standard recombination scheme, however additional resonance and ionizing radiation sources can delay recombination, altering the cosmic ionization history and the cosmological inferences drawn from the cosmic microwave background data. We show that for recent observations of the cosmic microwave background anisotropy, from the Wilkinson microwave anisotropy probe satellite mission (WMAP) 5-year survey and from the arcminute cosmology bolometer array receiver experiment, additional resonance radiation is nearly degenerate with variations in the spectral index, n s , and has a marked effect on uncertainties in constraints on the Hubble constant, age of the universe, curvature and the upper bound on the neutrino mass. When a modified recombination scheme is considered, the redshift of recombination is constrained to z * =1078±11, with uncertainties in the measurement weaker by 1 order of magnitude than those obtained under the assumption of standard recombination while constraints on the shift parameter are shifted by 1σ to R=1.734±0.028. From the WMAP5 data we obtain the following constraints on the resonance and ionization sources parameters: ε α i <0.058 at 95% c.l.. Although delayed recombination limits the precision of parameter estimation from the WMAP satellite, we demonstrate that this should not be the case for future, smaller angular scales measurements, such as those by the Planck satellite mission.

  17. Incorporation of Human Recombinant Tropoelastin into Silk Fibroin Membranes with the View to Repairing Bruch’s Membrane

    Directory of Open Access Journals (Sweden)

    Audra M. A. Shadforth

    2015-09-01

    Full Text Available Bombyx mori silk fibroin membranes provide a potential delivery vehicle for both cells and extracellular matrix (ECM components into diseased or injured tissues. We have previously demonstrated the feasibility of growing retinal pigment epithelial cells (RPE on fibroin membranes with the view to repairing the retina of patients afflicted with age-related macular degeneration (AMD. The goal of the present study was to investigate the feasibility of incorporating the ECM component elastin, in the form of human recombinant tropoelastin, into these same membranes. Two basic strategies were explored: (1 membranes prepared from blended solutions of fibroin and tropoelastin; and (2 layered constructs prepared from sequentially cast solutions of fibroin, tropoelastin, and fibroin. Optimal conditions for RPE attachment were achieved using a tropoelastin-fibroin blend ratio of 10 to 90 parts by weight. Retention of tropoelastin within the blend and layered constructs was confirmed by immunolabelling and Fourier-transform infrared spectroscopy (FTIR. In the layered constructs, the bulk of tropoelastin was apparently absorbed into the initially cast fibroin layer. Blend membranes displayed higher elastic modulus, percentage elongation, and tensile strength (p < 0.01 when compared to the layered constructs. RPE cell response to fibroin membranes was not affected by the presence of tropoelastin. These findings support the potential use of fibroin membranes for the co-delivery of RPE cells and tropoelastin.

  18. RPA homologs and ssDNA processing during meiotic recombination.

    Science.gov (United States)

    Ribeiro, Jonathan; Abby, Emilie; Livera, Gabriel; Martini, Emmanuelle

    2016-06-01

    Meiotic homologous recombination is a specialized process that involves homologous chromosome pairing and strand exchange to guarantee proper chromosome segregation and genetic diversity. The formation and repair of DNA double-strand breaks (DSBs) during meiotic recombination differs from those during mitotic recombination in that the homologous chromosome rather than the sister chromatid is the preferred repair template. The processing of single-stranded DNA (ssDNA) formed on intermediate recombination structures is central to driving the specific outcomes of DSB repair during meiosis. Replication protein A (RPA) is the main ssDNA-binding protein complex involved in DNA metabolism. However, the existence of RPA orthologs in plants and the recent discovery of meiosis specific with OB domains (MEIOB), a widely conserved meiosis-specific RPA1 paralog, strongly suggest that multiple RPA complexes evolved and specialized to subdivide their roles during DNA metabolism. Here we review ssDNA formation and maturation during mitotic and meiotic recombination underlying the meiotic specific features. We describe and discuss the existence and properties of MEIOB and multiple RPA subunits in plants and highlight how they can provide meiosis-specific fates to ssDNA processing during homologous recombination. Understanding the functions of these RPA homologs and how they interact with the canonical RPA subunits is of major interest in the fields of meiosis and DNA repair.

  19. Enhanced defects recombination in ion irradiated SiC

    International Nuclear Information System (INIS)

    Izzo, G.; Litrico, G.; Grassia, F.; Calcagno, L.; Foti, G.

    2010-01-01

    Point defects induced in SiC by ion irradiation show a recombination at temperatures as low as 320 K and this process is enhanced after running current density ranging from 80 to 120 A/cm 2 . Ion irradiation induces in SiC the formation of different defect levels and low-temperature annealing changes their concentration. Some levels (S 0 , S x and S 2 ) show a recombination and simultaneously a new level (S 1 ) is formed. An enhanced recombination of defects is besides observed after running current in the diode at room temperature. The carriers introduction reduces the S 2 trap concentration, while the remaining levels are not modified. The recombination is negligible up to a current density of 50 A/cm 2 and increases at higher current density. The enhanced recombination of the S 2 trap occurs at 300 K, which otherwise requires a 400 K annealing temperature. The process can be related to the electron-hole recombination at the associated defect.

  20. Formation of double layers

    International Nuclear Information System (INIS)

    Leung, P.; Wong, A.Y.; Quon, B.H.

    1981-01-01

    Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

  1. Fast Dissemination of New HIV-1 CRF02/A1 Recombinants in Pakistan.

    Directory of Open Access Journals (Sweden)

    Yue Chen

    Full Text Available A number of HIV-1 subtypes are identified in Pakistan by characterization of partial viral gene sequences. Little is known whether new recombinants are generated and how they disseminate since whole genome sequences for these viruses have not been characterized. Near full-length genome (NFLG sequences were obtained by amplifying two overlapping half genomes or next generation sequencing from 34 HIV-1-infected individuals in Pakistan. Phylogenetic tree analysis showed that the newly characterized sequences were 16 subtype As, one subtype C, and 17 A/G recombinants. Further analysis showed that all 16 subtype A1 sequences (47%, together with the vast majority of sequences from Pakistan from other studies, formed a tight subcluster (A1a within the subtype A1 clade, suggesting that they were derived from a single introduction. More in-depth analysis of 17 A/G NFLG sequences showed that five shared similar recombination breakpoints as in CRF02 (15% but were phylogenetically distinct from the prototype CRF02 by forming a tight subcluster (CRF02a while 12 (38% were new recombinants between CRF02a and A1a or a divergent A1b viruses. Unique recombination patterns among the majority of the newly characterized recombinants indicated ongoing recombination. Interestingly, recombination breakpoints in these CRF02/A1 recombinants were similar to those in prototype CRF02 viruses, indicating that recombination at these sites more likely generate variable recombinant viruses. The dominance and fast dissemination of new CRF02a/A1 recombinants over prototype CRF02 suggest that these recombinant have more adapted and may become major epidemic strains in Pakistan.

  2. Fast Dissemination of New HIV-1 CRF02/A1 Recombinants in Pakistan

    Science.gov (United States)

    Chen, Yue; Hora, Bhavna; DeMarco, Todd; Shah, Sharaf Ali; Ahmed, Manzoor; Sanchez, Ana M.; Su, Chang; Carter, Meredith; Stone, Mars; Hasan, Rumina; Hasan, Zahra; Busch, Michael P.; Denny, Thomas N.; Gao, Feng

    2016-01-01

    A number of HIV-1 subtypes are identified in Pakistan by characterization of partial viral gene sequences. Little is known whether new recombinants are generated and how they disseminate since whole genome sequences for these viruses have not been characterized. Near full-length genome (NFLG) sequences were obtained by amplifying two overlapping half genomes or next generation sequencing from 34 HIV-1-infected individuals in Pakistan. Phylogenetic tree analysis showed that the newly characterized sequences were 16 subtype As, one subtype C, and 17 A/G recombinants. Further analysis showed that all 16 subtype A1 sequences (47%), together with the vast majority of sequences from Pakistan from other studies, formed a tight subcluster (A1a) within the subtype A1 clade, suggesting that they were derived from a single introduction. More in-depth analysis of 17 A/G NFLG sequences showed that five shared similar recombination breakpoints as in CRF02 (15%) but were phylogenetically distinct from the prototype CRF02 by forming a tight subcluster (CRF02a) while 12 (38%) were new recombinants between CRF02a and A1a or a divergent A1b viruses. Unique recombination patterns among the majority of the newly characterized recombinants indicated ongoing recombination. Interestingly, recombination breakpoints in these CRF02/A1 recombinants were similar to those in prototype CRF02 viruses, indicating that recombination at these sites more likely generate variable recombinant viruses. The dominance and fast dissemination of new CRF02a/A1 recombinants over prototype CRF02 suggest that these recombinant have more adapted and may become major epidemic strains in Pakistan. PMID:27973597

  3. Numerical simulation of growth of flames formed in two-dimensional mixing layer. 2nd Report. Effect of dilution of fuel; Nijigen kongo sonai ni keiseisareta kaen no seicho ni kansuru suchi simulation. 2. Nenryo no kishaku ni yoru eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Noda, S [Toyohashi University of Technology, Aichi (Japan); Hashimoto, K [Sumitomo Metal Industries, Ltd., Osaka (Japan); Nakajima, T [Kobe University, Kobe (Japan). Faculty of Engineering

    1994-07-25

    The effect of fuel dilution on growth of flames formed in 2-D mixing layers was studied by numerical simulation. The methane mass fraction of fuel was adjusted to 1.0, 0.3 and 0.2 through dilution by nitrogen, while the oxygen mass fraction of an oxidizer was fixed at 0.27. Flame structure was complicated due to the flows separated by flame at the leading edge of flames, and three peaks of the second Damkohler number were observed. Fuel dilution by nitrogen caused blow-off of flames, and the mixing ratio of the fuel and oxidizer at the leading edge of flames was essential to blow-off of diffused flames. In the case where vortices were observed in a flow field, the first Damkohler number was important which was determined by the hydrodynamic characteristic time of coherent vortices and the chemical characteristic time of flame propagation based on the mixing ratio of the fuel and oxidizer at the leading edge of flames. The diffused flames were elongated by shearing force, and an exothermic reaction was suppressed and a flame stabilization decreased with a decrease in second Damkohler number. 10 refs., 9 figs., 1 tab.

  4. Nonequilibrium recombination after a curved shock wave

    Science.gov (United States)

    Wen, Chihyung; Hornung, Hans

    2010-02-01

    The effect of nonequilibrium recombination after a curved two-dimensional shock wave in a hypervelocity dissociating flow of an inviscid Lighthill-Freeman gas is considered. An analytical solution is obtained with the effective shock values derived by Hornung (1976) [5] and the assumption that the flow is ‘quasi-frozen’ after a thin dissociating layer near the shock. The solution gives the expression of dissociation fraction as a function of temperature on a streamline. A rule of thumb can then be provided to check the validity of binary scaling for experimental conditions and a tool to determine the limiting streamline that delineates the validity zone of binary scaling. The effects on the nonequilibrium chemical reaction of the large difference in free stream temperature between free-piston shock tunnel and equivalent flight conditions are discussed. Numerical examples are presented and the results are compared with solutions obtained with two-dimensional Euler equations using the code of Candler (1988) [10].

  5. Functions and structures of eukaryotic recombination proteins

    International Nuclear Information System (INIS)

    Ogawa, Tomoko

    1994-01-01

    We have found that Rad51 and RecA Proteins form strikingly similar structures together with dsDNA and ATP. Their right handed helical nucleoprotein filaments extend the B-form DNA double helixes to 1.5 times in length and wind the helix. The similarity and uniqueness of their structures must reflect functional homologies between these proteins. Therefore, it is highly probable that similar recombination proteins are present in various organisms of different evolutional states. We have succeeded to clone RAD51 genes from human, mouse, chicken and fission yeast genes, and found that the homologues are widely distributed in eukaryotes. The HsRad51 and MmRad51 or ChRad51 proteins consist of 339 amino acids differing only by 4 or 12 amino acids, respectively, and highly homologous to both yeast proteins, but less so to Dmcl. All of these proteins are homologous to the region from residues 33 to 240 of RecA which was named ''homologous core. The homologous core is likely to be responsible for functions common for all of them, such as the formation of helical nucleoprotein filament that is considered to be involved in homologous pairing in the recombination reaction. The mouse gene is transcribed at a high level in thymus, spleen, testis, and ovary, at lower level in brain and at a further lower level in some other tissues. It is transcribed efficiently in recombination active tissues. A clear functional difference of Rad51 homologues from RecA was suggested by the failure of heterologous genes to complement the deficiency of Scrad51 mutants. This failure seems to reflect the absence of a compatible partner, such as ScRad52 protein in the case of ScRad51 protein, between different species. Thus, these discoveries play a role of the starting point to understand the fundamental gene targeting in mammalian cells and in gene therapy. (J.P.N.)

  6. Crystal orientation of monoclinic β-Ga2O3 thin films formed on cubic MgO substrates with a γ-Ga2O3 interfacial layer

    Science.gov (United States)

    Nakagomi, Shinji; Kokubun, Yoshihiro

    2017-12-01

    The crystal orientation relationship between β-Ga2O3 and MgO in β-Ga2O3 thin films prepared on (1 0 0), (1 1 1), and (1 1 0) MgO substrates was investigated by X-ray diffraction measurements and cross-sectional transmission electron microscopy images. The γ-Ga2O3 interfacial layer was present between β-Ga2O3 and MgO acted as a buffer to connect β-Ga2O3 on MgO. The following conditions were satisfied under each case: β-Ga2O3 (1 0 0)||MgO (1 0 0) and β-Ga2O3 [0 0 1]||MgO 〈0 1 1〉 for the formation of β-Ga2O3 on (1 0 0) MgO, and β-Ga2O3 (2 bar 0 1)||MgO (1 1 1) for the formation of β-Ga2O3 on (1 1 1) MgO, as well as each condition of β-Ga2O3 [0 1 0] (1 0 0)||MgO [ 1 bar 1 0 ] (0 0 1), β-Ga2O3 [0 1 0] (1 0 0)||MgO [ 0 1 bar 1 ] (1 0 0), and β-Ga2O3 [0 1 0] (1 0 0)||MgO [ 1 0 1 bar ] (0 1 0). β-Ga2O3 (1 bar 0 2)||MgO(1 1 0) and β-Ga2O3 [0 1 0] ⊥ MgO [0 0 1] for β-Ga2O3 formed on (1 1 0) MgO. The β-Ga2O3 formed on (1 1 1) MgO at 800 °C exhibited a threefold structure. The β-Ga2O3 formed on (1 1 0) MgO had a twofold structure but different by 90° from the result reported previously.

  7. The effects of interfacial recombination and injection barrier on the electrical characteristics of perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Lin Xing Shi

    2018-02-01

    Full Text Available Charge carrier recombination in the perovskite solar cells (PSCs has a deep influence on the electrical performance, such as open circuit voltage, short circuit current, fill factor and ultimately power conversion efficiency. The impacts of injection barrier, recombination channels, doping properties of carrier transport layers and light intensity on the performance of PSCs are theoretically investigated by drift-diffusion model in this work. The results indicate that due to the injection barrier at the interfaces of perovskite and carrier transport layer, the accumulated carriers modify the electric field distribution throughout the PSCs. Thus, a zero electric field is generated at a specific applied voltage, with greatly increases the interfacial recombination, resulting in a local kink of current density-voltage (J-V curve. This work provides an effective strategy to improve the efficiency of PSCs by pertinently reducing both the injection barrier and interfacial recombination.

  8. To the reaction of silyl radicals. The ratio of disproportionation/recombination

    International Nuclear Information System (INIS)

    Reimann, B.; Matten, A.; Laupert, R.; Potzinger, P.

    1977-01-01

    Silyl radicals react in two distinct ways: (1) recombination to a vibrationally highly excited disilane, and (2) disproportionation to silylene and silane. Silylene disappears by a very fast insertion reaction in which disilane is formed. - Both reaction paths (1) and (2) can be distinguished by isotopic labelling. Disilane formed by (1), either undergoes unimolecular decomposition forming silylene and silane or it is stabilized through collisions. The ratio of disproportionation to recombination products is therefore pressure dependent. The disproportionation to recombination ratio, as calculated by extrapolation to infinite pressure, is 0.7 +- 0.1. - Photoionization mass spectrometry has been applied for the quantitative analysis of the deuterated disilanes. (orig.) [de

  9. Methods for forming particles

    Science.gov (United States)

    Fox, Robert V.; Zhang, Fengyan; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin

    2016-06-21

    Single source precursors or pre-copolymers of single source precursors are subjected to microwave radiation to form particles of a I-III-VI.sub.2 material. Such particles may be formed in a wurtzite phase and may be converted to a chalcopyrite phase by, for example, exposure to heat. The particles in the wurtzite phase may have a substantially hexagonal shape that enables stacking into ordered layers. The particles in the wurtzite phase may be mixed with particles in the chalcopyrite phase (i.e., chalcopyrite nanoparticles) that may fill voids within the ordered layers of the particles in the wurtzite phase thus produce films with good coverage. In some embodiments, the methods are used to form layers of semiconductor materials comprising a I-III-VI.sub.2 material. Devices such as, for example, thin-film solar cells may be fabricated using such methods.

  10. Heterogeneity within populations of recombinant Chinese hamster ovary cells expressing human interferon-gamma.

    Science.gov (United States)

    Coppen, S R; Newsam, R; Bull, A T; Baines, A J

    1995-04-20

    The Chinese hamster ovary (CHO) cell line has great commercial importance in the production of recombinant human proteins, especially those for therapeutic use. Much attention has been paid to CHO cell population physiology in order to define factors affecting product fidelity and yield. Such studies have revealed that recombinant proteins, including human interferon-gamma (IFN-gamma), can be heterogeneous both in glycosylation and in proteolytic processing. The type of heterogeneity observed depends on the growth physiology of the cell population, although the relationship between them is complex. In this article we report results of a cytological study of the CHO320 line which expresses recombinant human IFN-gamma. When grown in suspension culture, this cell line exhibited three types of heterogeneity: (1) heterogeneity of the production of IFN-gamma within the cell population, (2) heterogeneity of the number of nuclei and mitotic spindles in dividing cells, and (3) heterogeneity of cellular environment. The last of these arises from cell aggregates which form in suspension culture: Some cells are exposed to the culture medium; others are fully enclosed within the mass with little or no direct access to the medium. Thus, live cells producing IFN-gamma are heterogeneous in their environment, with variable access to O(2) and nutrients. Within the aggregates, it appears that live cells proliferate on a dead cell mass. The layer of live cells can be several cells deep. Specific cell-cell attachments are observed between the living cells in these aggregates. Two proteins, known to be required for the formation of certain types of intercellular junctions, spectrin and vinculin, have been localized to the regions of cell-cell contact. The aggregation of the cells appears to be an active process requiring protein synthesis. (c) 1995 John Wiley & Sons, Inc.

  11. Potential role of recombinant secretory leucoprotease inhibitor in the prevention of neutrophil mediated matrix degradation.

    Science.gov (United States)

    Llewellyn-Jones, C G; Lomas, D A; Stockley, R A

    1994-06-01

    Neutrophil elastase is able to degrade connective tissue matrices and is thought to be involved in the pathogenesis of destructive lung diseases. The ability of recombinant secretory leucoprotease inhibitor (rSLPI) to inhibit neutrophil mediated degradation of fibronectin in vitro is demonstrated and its efficacy compared with native alpha-1-proteinase inhibitor (n alpha 1-PI), recombinant alpha-1-proteinase inhibitor (r alpha 1-PI), and the chemical elastase inhibitor ICI 200,355. When preincubated with neutrophils both rSLPI and r alpha 1-PI were effective inhibitors of fibronectin degradation although n alpha 1-PI and ICI 200,355 were less effective. Recombinant SLPI was the most effective inhibitor when the cells were allowed to adhere to fibronectin before the addition of the inhibitors. Preincubation of rSLPI (0.1 mumol/l) with the fibronectin plate resulted in almost total inhibition of fibronectin degradation (reduced to 3.3 (SE 0.9)% of control). Pretreating the fibronectin plate with 1 mumol/l rSLPI, r alpha 1-PI and ICI 200,355 followed by thorough washing before the addition of cells resulted in no inhibition of fibronectin degradation with r alpha 1-PI and the ICI inhibitor, but rSLPI retained its inhibitory effect. This effect could be reduced by adding rSLPI in high pH buffer or 2 mol/1 NaCl. It is postulated that rSLPI binds to fibronectin to form a protective layer which prevents its degradation by neutrophil elastase. It may prove to be the most useful therapeutic agent in the prevention of neutrophil mediated lung damage.

  12. Binding of recombinant apolipoprotein(a) to extracellular matrix proteins

    NARCIS (Netherlands)

    van der Hoek, Y. Y.; Sangrar, W.; Côté, G. P.; Kastelein, J. J.; Koschinsky, M. L.

    1994-01-01

    Elevated levels of lipoprotein(a), which consists of apolipoprotein(a) [apo(a)] covalently linked to a low-density lipoprotein-like moiety, is an independent risk factor for the development of atherosclerosis. We show that a recombinant form of apo(a) [r-apo(a)] binds strongly to fibronectin and

  13. Processes for multi-layer devices utilizing layer transfer

    Science.gov (United States)

    Nielson, Gregory N; Sanchez, Carlos Anthony; Tauke-Pedretti, Anna; Kim, Bongsang; Cederberg, Jeffrey; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

    2015-02-03

    A method includes forming a release layer over a donor substrate. A plurality of devices made of a first semiconductor material are formed over the release layer. A first dielectric layer is formed over the plurality of devices such that all exposed surfaces of the plurality of devices are covered by the first dielectric layer. The plurality of devices are chemically attached to a receiving device made of a second semiconductor material different than the first semiconductor material, the receiving device having a receiving substrate attached to a surface of the receiving device opposite the plurality of devices. The release layer is etched to release the donor substrate from the plurality of devices. A second dielectric layer is applied over the plurality of devices and the receiving device to mechanically attach the plurality of devices to the receiving device.

  14. PROGENITORS OF RECOMBINING SUPERNOVA REMNANTS

    Energy Technology Data Exchange (ETDEWEB)

    Moriya, Takashi J., E-mail: takashi.moriya@ipmu.jp [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8583 (Japan)

    2012-05-01

    Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

  15. Meiotic recombination in human oocytes.

    Directory of Open Access Journals (Sweden)

    Edith Y Cheng

    2009-09-01

    Full Text Available Studies of human trisomies indicate a remarkable relationship between abnormal meiotic recombination and subsequent nondisjunction at maternal meiosis I or II. Specifically, failure to recombine or recombination events located either too near to or too far from the centromere have been linked to the origin of human trisomies. It should be possible to identify these abnormal crossover configurations by using immunofluorescence methodology to directly examine the meiotic recombination process in the human female. Accordingly, we initiated studies of crossover-associated proteins (e.g., MLH1 in human fetal oocytes to analyze their number and distribution on nondisjunction-prone human chromosomes and, more generally, to characterize genome-wide levels of recombination in the human female. Our analyses indicate that the number of MLH1 foci is lower than predicted from genetic linkage analysis, but its localization pattern conforms to that expected for a crossover-associated protein. In studies of individual chromosomes, our observations provide evidence for the presence of "vulnerable" crossover configurations in the fetal oocyte, consistent with the idea that these are subsequently translated into nondisjunctional events in the adult oocyte.

  16. Serendipitous identification of natural intergenotypic recombinants of hepatitis C in Ireland.

    LENUS (Irish Health Repository)

    Moreau, Isabelle

    2006-01-01

    BACKGROUND: Recombination between hepatitis C single stranded RNA viruses is a rare event. Natural viable intragenotypic and intergenotypic recombinants between 1b-1a, 1a-1c and 2k-1b, 2i-6p, respectively, have been reported. Diagnostically recombinants represent an intriguing challenge. Hepatitis C genotype is defined by interrogation of the sequence composition of the 5\\' untranslated region [5\\'UTR]. Occasionally, ambiguous specimens require further investigation of the genome, usually by interrogation of the NS5B region. The original purpose of this study was to confirm the existence of a suspected mixed genotype infection of genotypes 2 and 4 by clonal analysis at the NS5B region of the genome in two specimens from two separate individuals. This initial identification of genotype was based on analysis of the 5\\'UTR of the genome by reverse line probe hybridisation [RLPH]. RESULTS: The original diagnosis of a mixed genotype infection was not confirmed by clonal analysis of the NS5B region of the genome. The phylogenetic analysis indicated that both specimens were natural intergenotypic recombinant forms of HCV. The recombination was between genotypes 2k and 1b for both specimens. The recombination break point was identified as occurring within the NS2 region of the genome. CONCLUSION: The viral recombinants identified here resemble the recombinant form originally identified in Russia. The RLPH pattern observed in this study may be a signature indicative of this particular type of intergenotype recombinant of hepatitis C meriting clonal analysis of NS2.

  17. Photocharge accumulation and recombination in perovskite solar cells regarding device performance and stability

    Science.gov (United States)

    Li, Yusheng; Li, Yiming; Shi, Jiangjian; Li, Hongshi; Zhang, Huiyin; Wu, Jionghua; Li, Dongmei; Luo, Yanhong; Wu, Huijue; Meng, Qingbo

    2018-01-01

    Photocharge accumulation and recombination in perovskite solar cells have been systematically investigated in this paper by electrochemical spectroscopy and transient photocurrent/photovoltage methods. It is found that the non-equilibrium photocharges stored in the selective charge transport layers follow a backward recombination mechanism. That is, the photocharges are first captured by the interface defects corresponding to the fast photovoltage decay, while the bulk charge recombination instead of the diffusion process dominates the slow photovoltage decay process. Further investigation reveals that the device degradation preferentially takes place at the interface under working conditions, which thus can confirm the importance of interface engineering to enhance the device stability.

  18. Electric hydrogen recombiner special tests

    International Nuclear Information System (INIS)

    Wilson, J.F.

    1975-12-01

    Westinghouse has produced an electric hydrogen recombiner to control hydrogen levels in reactor containments following a postulated loss-of-coolant accident. The recombiner underwent extensive testing for NRC qualification (see WCAP 7709-L and Supplements 1, 2, 3, 4). As a result, WCAP 7709-L and Supplements 1, 2, 3, and 4 have been accepted by the NRC for reference in applications not committed to IEEE-323-1974. Supplement 5 and the next supplement will demonstrate conformance to IEEE-323-1974. This supplement describes additional tests, beyond those necessary to qualify the system, which will be referenced in supplement 6. Each test has demonstrated a considerable margin of safety over required performance. Concurrently, the test results increased the fund of technical information on the electric hydrogen recombiner

  19. Influence of different sulfur to selenium ratios on the structural and electronic properties of Cu(In,Ga)(S,Se){sub 2} thin films and solar cells formed by the stacked elemental layer process

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, B. J., E-mail: bjm.mueller@web.de [Robert Bosch GmbH, Corporate Research and Advance Engineering, Advanced Functional Materials and Microsystems, D-70839 Gerlingen (Germany); Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany); Zimmermann, C.; Haug, V., E-mail: veronika.haug@de.bosch.com; Koehler, T.; Zweigart, S. [Robert Bosch GmbH, Corporate Research and Advance Engineering, Advanced Functional Materials and Microsystems, D-70839 Gerlingen (Germany); Hergert, F. [Bosch Solar CISTech GmbH, D-14772 Brandenburg (Germany); Herr, U., E-mail: ulrich.herr@uni-ulm.de [Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany)

    2014-11-07

    In this study, we investigate the effect of different elemental selenium to elemental sulfur ratios on the chalcopyrite phase formation in Cu(In,Ga)(S,Se){sub 2} thin films. The films are formed by the stacked elemental layer process. The structural and electronic properties of the thin films and solar cells are analyzed by means of scanning electron microscopy, glow discharge optical emission spectrometry, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, spectral photoluminescence as well as current-voltage, and quantum efficiency measurements. The influence of different S/(S+Se) ratios on the anion incorporation and on the Ga/In distribution is investigated. We find a homogenous sulfur concentration profile inside the film from the top surface to the bottom. External quantum efficiency measurements show that the band edge of the solar cell device is shifted to shorter wavelength, which enhances the open-circuit voltages. The relative increase of the open-circuit voltage with S/(S+Se) ratio is lower than expected from the band gap energy trend, which is attributed to the presence of S-induced defects. We also observe a linear decrease of the short-circuit current density with increasing S/(S+Se) ratio which can be explained by a reduced absorption. Above a critical S/(S+Se) ratio of around 0.61, the fill factor drops drastically, which is accompanied by a strong series resistance increase which may be attributed to changes in the back contact or p-n junction properties.

  20. Characterization of rust layer formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich environment by Cl and Fe K-edge XANES measurements

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganeite, lepidocrocite and magnetite. Among these iron oxides, akaganeite in particular is the major component in the rust. Additionally, the amount of akaganeite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganeite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganeite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganeite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel. (author)

  1. Influenza vaccines: from whole virus preparations to recombinant protein technology.

    Science.gov (United States)

    Huber, Victor C

    2014-01-01

    Vaccination against influenza represents our most effective form of prevention. Historical approaches toward vaccine creation and production have yielded highly effective vaccines that are safe and immunogenic. Despite their effectiveness, these historical approaches do not allow for the incorporation of changes into the vaccine in a timely manner. In 2013, a recombinant protein-based vaccine that induces immunity toward the influenza virus hemagglutinin was approved for use in the USA. This vaccine represents the first approved vaccine formulation that does not require an influenza virus intermediate for production. This review presents a brief history of influenza vaccines, with insight into the potential future application of vaccines generated using recombinant technology.

  2. Recombination-deficient mutants of Bacillus subtilis

    International Nuclear Information System (INIS)

    Sadaie, Y.; Kada, T.

    1976-01-01

    Two mutant strains of Bacillus subtilis Marburg, NIG43 and NIG45, were isolated. They showed high sensitivities to gamma rays, ultraviolet light (uv), and chemicals. Deficiencies in genetic recombination of these two mutants were shown by the experiments on their capacity in transformation, SPO2 transfection, and PBS1 phage transduction, as well as on their radiation and drug sensitivities and their Hcr + capacity for uv-exposed phage M2. Some of these characteristics were compared with those of the known strains possessing the recA1 or recB2 alleles. Mapping studies revealed that the mutation rec-43 of strain NIG43 lies in the region of chromosome replication origin. The order was purA dna-8132 rec-43. Another mutation, rec-45, of strain NIG45 was found to be tightly linked to recA1. The mutation rec-43 reduced mainly the frequency of PBS1 transduction. On the other hand, the mutation rec-45 reduced the frequency of recombination involved both in transformation and PBS1 tranduction. The mutation rec-43 of strain NIG43 is conditional, but rec-45 of strain NIG45 is not. The uv impairment in cellular survival of strain NIG43 was gradually reverted at higher salt or sucrose concentrations, suggesting cellular possession of a mutated gene product whose function is conditional. In contrast to several other recombination-deficient strains, SPO2 lysogens of strains NIG43 and NIG45 were not inducible, indicating involvement of rec-43 + or rec-45 + gene product in the development of SPO2 prophage to a vegetative form. The uv-induced deoxyribonucleic acid degradation in vegetative cells was higher in rec-43 and rec-45 strains

  3. Polymer:Nonfullerene Bulk Heterojunction Solar Cells with Exceptionally Low Recombination Rates

    KAUST Repository

    Gasparini, Nicola; Salvador, Michael; Heumueller, Thomas; Richter, Moses; Classen, Andrej; Shrestha, Shreetu; Matt, Gebhard J.; Holliday, Sarah; Strohm, Sebastian; Egelhaaf, Hans-Joachim; Wadsworth, Andrew; Baran, Derya; McCulloch, Iain; Brabec, Christoph J.

    2017-01-01

    Organic semiconductors are in general known to have an inherently lower charge carrier mobility compared to their inorganic counterparts. Bimolecular recombination of holes and electrons is an important loss mechanism and can often be described by the Langevin recombination model. Here, the device physics of bulk heterojunction solar cells based on a nonfullerene acceptor (IDTBR) in combination with poly(3-hexylthiophene) (P3HT) are elucidated, showing an unprecedentedly low bimolecular recombination rate. The high fill factor observed (above 65%) is attributed to non-Langevin behavior with a Langevin prefactor (β/βL) of 1.9 × 10−4. The absence of parasitic recombination and high charge carrier lifetimes in P3HT:IDTBR solar cells inform an almost ideal bimolecular recombination behavior. This exceptional recombination behavior is explored to fabricate devices with layer thicknesses up to 450 nm without significant performance losses. The determination of the photoexcited carrier mobility by time-of-flight measurements reveals a long-lived and nonthermalized carrier transport as the origin for the exceptional transport physics. The crystalline microstructure arrangement of both components is suggested to be decisive for this slow recombination dynamics. Further, the thickness-independent power conversion efficiency is of utmost technological relevance for upscaling production and reiterates the importance of understanding material design in the context of low bimolecular recombination.

  4. Polymer:Nonfullerene Bulk Heterojunction Solar Cells with Exceptionally Low Recombination Rates

    KAUST Repository

    Gasparini, Nicola

    2017-09-01

    Organic semiconductors are in general known to have an inherently lower charge carrier mobility compared to their inorganic counterparts. Bimolecular recombination of holes and electrons is an important loss mechanism and can often be described by the Langevin recombination model. Here, the device physics of bulk heterojunction solar cells based on a nonfullerene acceptor (IDTBR) in combination with poly(3-hexylthiophene) (P3HT) are elucidated, showing an unprecedentedly low bimolecular recombination rate. The high fill factor observed (above 65%) is attributed to non-Langevin behavior with a Langevin prefactor (β/βL) of 1.9 × 10−4. The absence of parasitic recombination and high charge carrier lifetimes in P3HT:IDTBR solar cells inform an almost ideal bimolecular recombination behavior. This exceptional recombination behavior is explored to fabricate devices with layer thicknesses up to 450 nm without significant performance losses. The determination of the photoexcited carrier mobility by time-of-flight measurements reveals a long-lived and nonthermalized carrier transport as the origin for the exceptional transport physics. The crystalline microstructure arrangement of both components is suggested to be decisive for this slow recombination dynamics. Further, the thickness-independent power conversion efficiency is of utmost technological relevance for upscaling production and reiterates the importance of understanding material design in the context of low bimolecular recombination.

  5. Experimental studies on catalytic hydrogen recombiners for light water reactors

    International Nuclear Information System (INIS)

    Drinovac, P.

    2006-01-01

    In the course of core melt accidents in nuclear power plants a large amount of hydrogen can be produced and form an explosive or even detonative gas mixture with aerial oxygen in the reactor building. In the containment atmosphere of pressurized water reactors hydrogen combines a phlogistically with the oxygen present to form water vapor even at room temperature. In the past, experimental work conducted at various facilities has contributed little or nothing to an understanding of the operating principles of catalytic recombiners. Hence, the purpose of the present study was to conduct detailed investigations on a section of a recombiner essentially in order to deepen the understanding of reaction kinetics and heat transport processes. The results of the experiments presented in this dissertation form a large data base of measurements which provides an insight into the processes taking place in recombiners. The reaction-kinetic interpretation of the measured data confirms and deepens the diffusion theory - proposed in an earlier study. Thus it is now possible to validate detailed numeric models representing the processes in recombiners. Consequently the present study serves to broaden and corroborate competence in this significant area of reactor technology. In addition, the empirical knowledge thus gained may be used for a critical reassessment of previous numeric model calculations. (orig.)

  6. Analysis of turbulent boundary layers

    CERN Document Server

    Cebeci, Tuncer

    1974-01-01

    Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculati

  7. Production and recombination of gluons

    International Nuclear Information System (INIS)

    Temiraliev, A.T.

    2006-01-01

    Full text: Nonlinear Markov process of parton production has been considered. The Kolmogorov equation is applied for the evolution equation based on the approximation of independent gluons production in every decay act. We introduced a 'crossing' parameter and used the combination relations to obtain nonlinear recombination equation for the evolution of gluon structure function. (author)

  8. Recombinator of hydrogen and oxygen

    International Nuclear Information System (INIS)

    Stejskal, J.; Klein, O.; Scholtz, G.; Schmidt, P.; Olaussson, A.

    1976-01-01

    Improvements are proposed for the well known reactors for the catalytic recombination of hydrogen and oxygen, which should permit this being used in contiuous operation in nuclear reactors (BWRs). The improvements concern the geometric arrangement of gas-inlet and -outlet pipes, the inclination of the axis of the catalyst container and the introduction of remote operation. (UWI) [de

  9. Improving recombinant protein purification yield

    Science.gov (United States)

    Production of adequate amounts of recombinant proteins is essential for antibody production, biochemical activity study, and structural determination during the post-genomic era. It’s technologically challenging and a limiting factor for tung oil research because analytical reagents such as high qua...

  10. Recombination in hepatitis C virus.

    Science.gov (United States)

    González-Candelas, Fernando; López-Labrador, F Xavier; Bracho, María Alma

    2011-10-01

    Hepatitis C virus (HCV) is a Flavivirus with a positive-sense, single-stranded RNA genome of about 9,600 nucleotides. It is a major cause of liver disease, infecting almost 200 million people all over the world. Similarly to most RNA viruses, HCV displays very high levels of genetic diversity which have been used to differentiate six major genotypes and about 80 subtypes. Although the different genotypes and subtypes share basic biological and pathogenic features they differ in clinical outcomes, response to treatment and epidemiology. The first HCV recombinant strain, in which different genome segments derived from parentals of different genotypes, was described in St. Petersburg (Russia) in 2002. Since then, there have been only a few more than a dozen reports including descriptions of HCV recombinants at all levels: between genotypes, between subtypes of the same genotype and even between strains of the same subtype. Here, we review the literature considering the reasons underlying the difficulties for unequivocally establishing recombination in this virus along with the analytical methods necessary to do it. Finally, we analyze the potential consequences, especially in clinical practice, of HCV recombination in light of the coming new therapeutic approaches against this virus.

  11. Multimer Formation Explains Allelic Suppression of PRDM9 Recombination Hotspots.

    Science.gov (United States)

    Baker, Christopher L; Petkova, Pavlina; Walker, Michael; Flachs, Petr; Mihola, Ondrej; Trachtulec, Zdenek; Petkov, Petko M; Paigen, Kenneth

    2015-09-01

    Genetic recombination during meiosis functions to increase genetic diversity, promotes elimination of deleterious alleles, and helps assure proper segregation of chromatids. Mammalian recombination events are concentrated at specialized sites, termed hotspots, whose locations are determined by PRDM9, a zinc finger DNA-binding histone methyltransferase. Prdm9 is highly polymorphic with most alleles activating their own set of hotspots. In populations exhibiting high frequencies of heterozygosity, questions remain about the influences different alleles have in heterozygous individuals where the two variant forms of PRDM9 typically do not activate equivalent populations of hotspots. We now find that, in addition to activating its own hotspots, the presence of one Prdm9 allele can modify the activity of hotspots activated by the other allele. PRDM9 function is also dosage sensitive; Prdm9+/- heterozygous null mice have reduced numbers and less active hotspots and increased numbers of aberrant germ cells. In mice carrying two Prdm9 alleles, there is allelic competition; the stronger Prdm9 allele can partially or entirely suppress chromatin modification and recombination at hotspots of the weaker allele. In cell cultures, PRDM9 protein variants form functional heteromeric complexes which can bind hotspots sequences. When a heteromeric complex binds at a hotspot of one PRDM9 variant, the other PRDM9 variant, which would otherwise not bind, can still methylate hotspot nucleosomes. We propose that in heterozygous individuals the underlying molecular mechanism of allelic suppression results from formation of PRDM9 heteromers, where the DNA binding activity of one protein variant dominantly directs recombination initiation towards its own hotspots, effectively titrating down recombination by the other protein variant. In natural populations with many heterozygous individuals, allelic competition will influence the recombination landscape.

  12. Recombination luminescence and trap levels in undoped and Al-doped ZnO thin films on quartz and GaSe (0 0 0 1) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Evtodiev, I. [Moldova State University, 60 A. Mateevici Str., Chisinau, MD 2009, Republic of Moldova (Moldova, Republic of); Caraman, I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Leontie, L., E-mail: lleontie@uaic.ro [Alexandru Ioan Cuza University of Iasi, Bd. Carol I, Nr. 11, RO 700506 Iasi (Romania); Rusu, D.-I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Dafinei, A. [Faculty of Physics, University of Bucharest, Platforma Magurele, Str. Fizicienilor nr. 1, CP Mg - 11, Bucharest-Magurele, RO 76900 (Romania); Nedeff, V.; Lazar, G. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer ZnO films on GaSe create electron trapping states and PL recombination levels. Black-Right-Pointing-Pointer Zn and Al diffusion in GaSe produces low-energy widening of its PL emission. Black-Right-Pointing-Pointer ZnO:Al films on GaSe lamellas are suitable for gas-discharge lamp applications. -- Abstract: Photoluminescence spectra of ZnO and ZnO:Al (1.00, 2.00 and 5.00 at.%) films on GaSe (0 0 0 1) lamellas and amorphous quartz substrates, obtained by annealing, at 700 K, of undoped and Al-doped metal films, are investigated. For all samples, the nonequilibrium charge carriers recombine by radiative band-to-band transitions with energy of 3.27 eV, via recombination levels created by the monoionized oxygen atoms, forming the impurity band laying in the region 2.00 - 2.70 eV. Al doping induces an additional recombination level at 1.13 eV above the top of the valence band of ZnO films on GaSe substrates. As a result of thermal diffusion of Zn and Al into the GaSe interface layer from ZnO:Al/GaSe heterojunction, electron trap levels located at 0.22 eV and 0.26 eV below the conduction band edge of GaSe, as well as a deep recombination level, responsible for the luminescent emission in the region 1.10 - 1.40 eV, are created.

  13. Functional, Responsive Materials Assembled from Recombinant Oleosin

    Science.gov (United States)

    Hammer, Daniel

    Biological cells are surrounded by a plasma membrane made primarily of phospholipids that form a bilayer. This membrane is permselective and compartmentalizes the cell. A simple form of artificial cell is the vesicle, in which a phospholipid bilayer membrane surrounds an aqueous solution. However, there is no a priori reason why a membrane needs to be made of phospholipids. It could be made of any surfactant that forms a bilayer. We have assembled membranes and other structures from the recombinant plant protein oleosin. The ability to assemble from a recombinant protein means that every molecule is identical, we have complete control over the sequence, and hence can build in designer functionality with high fidelity, including adhesion and enzymatic activity. Such incorporation is trivial using the tools of molecular biology. We find that while many variants of oleosin make membranes, others make micelles and sheets. We show how the type of supramolecular structure can be altered by the conditions of solvent, such as ionic strength, and the architecture of the surfactant itself. We show that protease cleavable domains can be incorporated within oleosin, and be engineered to protect other functional domains such as adhesive motifs, to make responsive materials whose activity and shape depend on the action of proteases. We will also present the idea of making ``Franken''-oleosins, where large domains of native oleosin are replaced with domains from other functional proteins, to make hybrids conferred by the donor protein. Thus, we can view oleosin as a template upon which a vast array of designer functionalities can be imparted..

  14. Article and method of forming an article

    Science.gov (United States)

    Lacy, Benjamin Paul; Kottilingam, Srikanth Chandrudu; Dutta, Sandip; Schick, David Edward

    2017-12-26

    Provided are an article and a method of forming an article. The method includes providing a metallic powder, heating the metallic powder to a temperature sufficient to joint at least a portion of the metallic powder to form an initial layer, sequentially forming additional layers in a build direction by providing a distributed layer of the metallic powder over the initial layer and heating the distributed layer of the metallic powder, repeating the steps of sequentially forming the additional layers in the build direction to form a portion of the article having a hollow space formed in the build direction, and forming an overhang feature extending into the hollow space. The article includes an article formed by the method described herein.

  15. Plasma-assisted atomic layer deposition of TiO2 compact layers for flexible mesostructured perovskite solar cells

    NARCIS (Netherlands)

    Zardetto, V.; Di Giacomo, F.; Lucarelli, G.; Kessels, W.M.M.; Brown, T.M.; Creatore, M.

    2017-01-01

    In mesostructured perovskite solar cell devices, charge recombination processes at the interface between the transparent conductive oxide, perovskite and hole transport layer are suppressed by depositing an efficient compact TiO2 blocking layer. In this contribution we investigate the role of the

  16. Live recombinant BHV/BRSV vaccine

    NARCIS (Netherlands)

    Keil, G.M.; Rijsewijk, F.A.M.

    1998-01-01

    The present invention refers to synthetic Bovine Respiratory Syncytium virus genes. Also the invention relates to live attenuated Bovine Herpesvirus recombinants carrying such synthetic genes. Furthermore, the invention relates to vaccines based on these live attenuated recombinants, for the

  17. Hadron production at RHIC: recombination of quarks

    Energy Technology Data Exchange (ETDEWEB)

    Fries, Rainer J [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2005-01-01

    We discuss quark recombination applied to the hadronization of a quark gluon plasma. It has been shown that the quark recombination model can explain essential features of hadron production measured in high energy heavy ion collisions.

  18. Affinity purification of recombinant human plasminogen activator ...

    African Journals Online (AJOL)

    Affinity purification of recombinant human plasminogen activator from ... Screening antibody was performed using rhPA milk in an ELISA-elution assay. ... useful for purifying other tPA mutants or other novel recombinant milkderived proteins.

  19. Recombinant innovation and endogenous technological transitions

    NARCIS (Netherlands)

    Frenken, K.; Izquierdo, L.R.; Zeppini, P.

    2012-01-01

    We propose a model of technological transitions based on two different types of innovations. Branching innovations refer to technological improvements along a particular path, while recombinant innovations represent fusions of multiple paths. Recombinant innovations create "short-cuts" which reduce

  20. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    Energy Technology Data Exchange (ETDEWEB)

    Yang Liang; Habibovic, Pamela; Van Blitterswijk, Clemens A [Department of Tissue Regeneration, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Hedhammar, My; Johansson, Jan [Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, the Biomedical Centre, Box 575, 751 23 Uppsala (Sweden); Blom, Tobias; Leifer, Klaus [Department of Engineering Sciences, Uppsala University, Box 534, S-751 21 Uppsala (Sweden)

    2010-08-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

  1. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    International Nuclear Information System (INIS)

    Yang Liang; Habibovic, Pamela; Van Blitterswijk, Clemens A; Hedhammar, My; Johansson, Jan; Blom, Tobias; Leifer, Klaus

    2010-01-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

  2. Expression and purification of recombinant polyomavirus VP2 protein and its interactions with polyomavirus proteins

    Science.gov (United States)

    Cai, X.; Chang, D.; Rottinghaus, S.; Consigli, R. A.; Spooner, B. S. (Principal Investigator)

    1994-01-01

    Recombinant polyomavirus VP2 protein was expressed in Escherichia coli (RK1448), using the recombinant expression system pFPYV2. Recombinant VP2 was purified to near homogeneity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroelution, and Extracti-Gel chromatography. Polyclonal serum to this protein which reacted specifically with recombinant VP2 as well as polyomavirus virion VP2 and VP3 on Western blots (immunoblots) was produced. Purified VP2 was used to establish an in vitro protein-protein interaction assay with polyomavirus structural proteins and purified recombinant VP1. Recombinant VP2 interacted with recombinant VP1, virion VP1, and the four virion histones. Recombinant VP1 coimmunoprecipitated with recombinant VP2 or truncated VP2 (delta C12VP2), which lacked the carboxy-terminal 12 amino acids. These experiments confirmed the interaction between VP1 and VP2 and revealed that the carboxyterminal 12 amino acids of VP2 and VP3 were not necessary for formation of this interaction. In vivo VP1-VP2 interaction study accomplished by cotransfection of COS-7 cells with VP2 and truncated VP1 (delta N11VP1) lacking the nuclear localization signal demonstrated that VP2 was capable of translocating delta N11VP1 into the nucleus. These studies suggest that complexes of VP1 and VP2 may be formed in the cytoplasm and cotransported to the nucleus for virion assembly to occur.

  3. Population inversion in recombining hydrogen plasma

    International Nuclear Information System (INIS)

    Furukane, Utaro; Yokota, Toshiaki; Oda, Toshiatsu.

    1978-11-01

    The collisional-radiative model is applied to a recombining hydrogen plasma in order to investigate the plasma condition in which the population inversion between the energy levels of hydrogen can be generated. The population inversion is expected in a plasma where the three body recombination has a large contribution to the recombining processes and the effective recombination rate is beyond a certain value for a given electron density and temperature. Calculated results are presented in figures and tables. (author)

  4. Regulation of homologous recombination in eukaryotes

    OpenAIRE

    Heyer, Wolf-Dietrich; Ehmsen, Kirk T.; Liu, Jie

    2010-01-01

    Homologous recombination is required for accurate chromosome segregation during the first meiotic division and constitutes a key repair and tolerance pathway for complex DNA damage including DNA double-stranded breaks, interstrand crosslinks, and DNA gaps. In addition, recombination and replication are inextricably linked, as recombination recovers stalled and broken replication forks enabling the evolution of larger genomes/replicons. Defects in recombination lead to genomic instability and ...

  5. The effect of a single recombination event

    DEFF Research Database (Denmark)

    Schierup, Mikkel Heide; Jensen, Thomas Mailund; Wiuf, Carsten

    We investigate the variance in how visible a single recombination event is in a SNP data set as a function of the type of recombination event and its age. Data is simulated under the coalescent with recombination and inference is by the popular composite likelihood methods. The major determinant...

  6. Picosecond kinetics of the electron-hole layers formation in wide-bandgap II-VI type-II heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Filatov, E.V.; Zaitsev, S.V.; Tartakovskii, I.I.; Maksimov, A.A. [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow region (Russian Federation); Yakovlev, D.R. [A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Experimentelle Physik II, Technische Universitaet Dortmund (Germany); Waag, A. [Institute of Semiconductor Technology, Braunschweig Technical University, 38106 Braunschweig (Germany)

    2010-06-15

    Considerable slowdown of luminescence kinetics of the direct optical transition was discovered in ZnSe/BeTe type-II heterostructures under high levels of optical pumping. The effect is attributed to forming of a potential barrier for holes in the ZnSe layer due to band bending at high densities of spatially separated carriers. That results in a longer time of the photoexcited holes energy relaxation to their ground state in the BeTe layer. The decrease of overlapping of electron and hole wavefunctions in the ZnSe layer in thick ZnSe/BeTe structures at high levels of optical excitation reveals an additional important effect, that leads to sufficient retardation of radiative recombination time for photoexcited carriers (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Al-Si alloy point contact formation and rear surface passivation for silicon solar cells using double layer porous silicon

    International Nuclear Information System (INIS)

    Moumni, Besma; Ben Jaballah, Abdelkader; Bessais, Brahim

    2012-01-01

    Lowering the rear surface recombination velocities by a dielectric layer has fascinating advantages compared with the standard fully covered Al back-contact silicon solar cells. In this work the passivation effect by double layer porous silicon (PS) (wide band gap) and the formation of Al-Si alloy in narrow p-type Si point contact areas for rear passivated solar cells are analysed. As revealed by Fourier transform infrared spectroscopy, we found that a thin passivating aluminum oxide (Al 2 O 3 ) layer is formed. Scanning electron microscopy analysis performed in cross sections shows that with bilayer PS, liquid Al penetrates into the openings, alloying with the Si substrate at depth and decreasing the contact resistivity. At the solar cell level, the reduction in the contact area and resistivity leads to a minimization of the fill factor losses.

  8. Hybrid window layer for photovoltaic cells

    Science.gov (United States)

    Deng, Xunming

    2010-02-23

    A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

  9. Recombination Catalysts for Hypersonic Fuels

    Science.gov (United States)

    Chinitz, W.

    1998-01-01

    The goal of commercially-viable access to space will require technologies that reduce propulsion system weight and complexity, while extracting maximum energy from the products of combustion. This work is directed toward developing effective nozzle recombination catalysts for the supersonic and hypersonic aeropropulsion engines used to provide such access to space. Effective nozzle recombination will significantly reduce rk=le length (hence, propulsion system weight) and reduce fuel requirements, further decreasing the vehicle's gross lift-off weight. Two such catalysts have been identified in this work, barium and antimony compounds, by developing chemical kinetic reaction mechanisms for these materials and determining the engine performance enhancement for a typical flight trajectory. Significant performance improvements are indicated, using only 2% (mole or mass) of these compounds in the combustor product gas.

  10. Mechanisms of sister chromatid recombination

    International Nuclear Information System (INIS)

    Nakai, Sayaka; Machida, Isamu; Tsuji, Satsuki

    1985-01-01

    Studies using T948 as a model system have been carried out aimed at elucidating the mechanism of sister chromatid recombination (SCR). Characterization of U.V. light- and x-ray-induced SCR, the relationiship between SCR induction and DNA repair using rad mutations, and the relationship between SCR induction and the time of cell division using cdc mutations are presented. It has been supposed that SCR is induced at the phase of S-G 2 following DNA replication, that postreplication break of DNA strands is strongly involved in the induction of SCR, and that induction type of SCR, i.e., conversion type or recombination type, is dependent upon the type of molecular damage of DNA. (Namekawa, K.)

  11. Interface recombination influence on carrier transport

    International Nuclear Information System (INIS)

    Konin, A

    2013-01-01

    A theory of interface recombination in the semiconductor–semiconductor junction is developed. The interface recombination rate dependence on the nonequilibrium carrier densities is derived on the basis of a model in which the interface recombination occurs through the mechanism of trapping. The general relation between the interface recombination parameters at small carrier density deviation from the equilibrium ones is obtained. The validity of this relation is proved considering the generation of the Hall electric field in the extrinsic semiconductor sample. The anomalous Hall electromotive force in a weak magnetic field was investigated and interpreted by means of a new interface recombination model. The experimental data corroborate the developed theory. (paper)

  12. Tunnel Oxides Formed by Field-Induced Anodisation for Passivated Contacts of Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Jingnan Tong

    2018-02-01

    Full Text Available Tunnel silicon oxides form a critical component for passivated contacts for silicon solar cells. They need to be sufficiently thin to allow carriers to tunnel through and to be uniform both in thickness and stoichiometry across the silicon wafer surface, to ensure uniform and low recombination velocities if high conversion efficiencies are to be achieved. This paper reports on the formation of ultra-thin silicon oxide layers by field-induced anodisation (FIA, a process that ensures uniform oxide thickness by passing the anodisation current perpendicularly through the wafer to the silicon surface that is anodised. Spectroscopical analyses show that the FIA oxides contain a lower fraction of Si-rich sub-oxides compared to wet-chemical oxides, resulting in lower recombination velocities at the silicon and oxide interface. This property along with its low temperature formation highlights the potential for FIA to be used to form low-cost tunnel oxide layers for passivated contacts of silicon solar cells.

  13. Recombinant Cyclophilins Lack Nuclease Activity

    OpenAIRE

    Manteca, Angel; Sanchez, Jesus

    2004-01-01

    Several single-domain prokaryotic and eukaryotic cyclophilins have been identified as also being unspecific nucleases with a role in DNA degradation during the lytic processes that accompany bacterial cell death and eukaryotic apoptosis. Evidence is provided here that the supposed nuclease activity of human and bacterial recombinant cyclophilins is due to contamination of the proteins by the host Escherichia coli endonuclease and is not an intrinsic property of these proteins.

  14. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  15. (EOI) Form

    International Development Research Centre (IDRC) Digital Library (Canada)

    Dorine Odongo

    COLLABORATING TECHNICAL AGENCIES: EXPRESSION OF INTEREST FORM. • Please read the information provided about the initiative and the eligibility requirements in the Prospectus before completing this application form. • Ensure all the sections of the form are accurately completed and saved in PDF format.

  16. Modular forms

    NARCIS (Netherlands)

    Edixhoven, B.; van der Geer, G.; Moonen, B.; Edixhoven, B.; van der Geer, G.; Moonen, B.

    2008-01-01

    Modular forms are functions with an enormous amount of symmetry that play a central role in number theory, connecting it with analysis and geometry. They have played a prominent role in mathematics since the 19th century and their study continues to flourish today. Modular forms formed the

  17. Workshop on Radio Recombination Lines

    CERN Document Server

    1980-01-01

    Since their first detection 15 years ago, radio recombination lines from several elements have been observed in a wide variety of objects including HII regions, planetary nebulae, molecular clouds, the diffuse interstellar medium, and recently, other galaxies. The observations span almost the entire range from 0.1 to 100 GHz, and employ both single­ djsh and aperture synthesis techniques. The theory of radio recombination lines has also advanced strongly, to the point where it is perhaps one of the best-understood in astro­ physics. In a parallel development, it has become possible over the last decade to study these same highly-excited atoms in the laboratory; this work provides further confirmation of the theoretical framework. However there has been continuing controversy over the astrophysical interpre­ tation of radio recombination line observations, especially regarding the role of stimulated emission. A workshop was held in Ottawa on 24-25 August, 1979, bringing together many of the active scientist...

  18. Back contact buffer layer for thin-film solar cells

    Science.gov (United States)

    Compaan, Alvin D.; Plotnikov, Victor V.

    2014-09-09

    A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.

  19. Forming lead-based anodes

    Energy Technology Data Exchange (ETDEWEB)

    Ogorodnichuk, V I; Voitsekhovich, R I

    1972-01-01

    Lead-based anodes can be produced by forming a layer of lead dioxide by chemical treatment in a solution of sulfuric acid in potassium permanganate at 80 to 100/sup 0/. The solution is mixed by compressed air. (RWR)

  20. Efficient red phosphorescent organic light emitting diodes with double emission layers

    International Nuclear Information System (INIS)

    Ben Khalifa, M; Mazzeo, M; Maiorano, V; Mariano, F; Carallo, S; Melcarne, A; Cingolani, R; Gigli, G

    2008-01-01

    We demonstrate efficient red phosphorescent organic light emitting diodes with a bipolar emission structure (D-EML) formed by two different layers doped with a red phosphorescent dye. Due to its self-balancing character, the recombination zone is shifted far from the emission/carrier-blocking-layer interfaces. This prevents the accumulation of carriers at the interfaces and reduces the triplet-triplet annihilation, resulting in an improved efficiency of the D-EML device compared with the standard single-EML architecture. However, a current efficiency of 8.4 cd A -1 at 10 mA cm -2 is achieved in the D-EML device compared with 3.7 cd A -1 in the single-EML device

  1. Efficient red phosphorescent organic light emitting diodes with double emission layers

    Energy Technology Data Exchange (ETDEWEB)

    Ben Khalifa, M; Mazzeo, M; Maiorano, V; Mariano, F; Carallo, S; Melcarne, A; Cingolani, R; Gigli, G [NNL, National Nanotechnology Laboratory of CNR-INFM, Distretto tecnologico ISUFI, Universita del Salento, Italy, Via per Arnesano, Km.5, 73100 Lecce (Italy)], E-mail: mohamed.benkhalifa@unile.it

    2008-08-07

    We demonstrate efficient red phosphorescent organic light emitting diodes with a bipolar emission structure (D-EML) formed by two different layers doped with a red phosphorescent dye. Due to its self-balancing character, the recombination zone is shifted far from the emission/carrier-blocking-layer interfaces. This prevents the accumulation of carriers at the interfaces and reduces the triplet-triplet annihilation, resulting in an improved efficiency of the D-EML device compared with the standard single-EML architecture. However, a current efficiency of 8.4 cd A{sup -1} at 10 mA cm{sup -2} is achieved in the D-EML device compared with 3.7 cd A{sup -1} in the single-EML device.

  2. Consequences of recombination on traditional phylogenetic analysis

    DEFF Research Database (Denmark)

    Schierup, M H; Hein, J

    2000-01-01

    We investigate the shape of a phylogenetic tree reconstructed from sequences evolving under the coalescent with recombination. The motivation is that evolutionary inferences are often made from phylogenetic trees reconstructed from population data even though recombination may well occur (mt......DNA or viral sequences) or does occur (nuclear sequences). We investigate the size and direction of biases when a single tree is reconstructed ignoring recombination. Standard software (PHYLIP) was used to construct the best phylogenetic tree from sequences simulated under the coalescent with recombination....... With recombination present, the length of terminal branches and the total branch length are larger, and the time to the most recent common ancestor smaller, than for a tree reconstructed from sequences evolving with no recombination. The effects are pronounced even for small levels of recombination that may...

  3. On the Fokker-Planck theory of electron three-body recombination

    International Nuclear Information System (INIS)

    Sayasov, Yu. S.

    1977-01-01

    The Fokker-Planck theory of electron three-body recombination based on the concept of electron diffusion along the energy scale in the excited hydrogen-like atoms formed in the recombining plasmas, is extended in several respects. 1) An universal formula for population distribution of the excited atoms in strongly ionized plasmas was found under a sole assumption, that the cross-sections for the inelastic atom-electron collisions are governed by the classical impulse approximation. 2) A general Fokker-Planck theory of the recombination in a slightly ionized, two-temperature plasmas was formulated. The recombination coefficients for such plasmas were shown to possess some peculiar properties in case the electronic temperature differs appreciable from the atomic one. A few limitations of the existing schemas for calculation of the recombination kinetics are briefly discussed. (orig.) [de

  4. PRODUCTION OF RECOMBINANT HIGH pI-BARLEY α-GLUCOSIDASE

    DEFF Research Database (Denmark)

    Næsted, Henrik; Svensson, Birte

    plantlet [1]. Recently, expression and characterization of the recombinant full length, fully functional barley high pI α-glucosidase in Pichia pastoris has been achieved. To enable production of recombinant protein in mg amounts, a transformant harbouring a clone encoding the N-terminally hexa histidine...... tagged recombinant form of the enzyme was propagated using a high cell-density fermentation procedure. This system resulted in successful expression under the highly sensitive methanol utilization phase conducting the fermentation process using a BiostatB 5 L reactor. The recombinant high pI α...... glycosylation of the recombinant α-glucosidase. The enzyme activity was highly stable during the 5 day long fermentation. Characterisation of the enzymatic properties confirmed the specific activity actually to be superior to that of the native enzyme purified from malt [2]. The kinetic parameters Km, Vmax...

  5. Magnesia nanoparticles in liquid electrolyte for dye sensitized solar cells: An effective recombination suppressant?

    International Nuclear Information System (INIS)

    Mohanty, Shyama Prasad; Bhargava, Parag

    2013-01-01

    Highlights: ► MgO loaded electrolyte retards recombination at titania/electrolyte interface. ► Recombination reactions are retarded by adsorption of anions on MgO in electrolyte. ► Zeta potential measurements show anionic adsorption on the surface of MgO. ► MgO loaded electrolyte performs efficiently than TBP containing electrolyte. -- Abstract: Recombination reactions at the photoanode/electrolyte interface reduce the photovoltaic conversion efficiency of dye sensitized solar cells (DSSCs). Unlike modification of titania photoanode by coating with MgO which act as a barrier layer toward recombination, addition of MgO nanopowder to electrolyte prevents recombination through adsorption of anions (triiodide/iodide) from electrolyte. In the present study, the surface charge of MgO has been utilized to adsorb anions from electrolyte. This anionic adsorption onto the MgO nanopowders in electrolyte has been confirmed by zeta potential measurements. MgO retards the recombination reaction as efficiently as 4-tert-butylpyridine (TBP) which is the most widely used additive in the electrolyte. Higher photocurrent and conversion efficiency is achieved by using MgO loaded electrolyte as compared to TBP added electrolyte. Dark current measurements show that recombination reactions are effectively retarded by use of MgO loaded electrolytes. Open circuit voltage decay measurements also confirm higher electron lifetime at the titania/electrolyte interface in MgO loaded electrolyte based cell as compared to additive free electrolyte based cell

  6. Fine-Scale Recombination Maps of Fungal Plant Pathogens Reveal Dynamic Recombination Landscapes and Intragenic Hotspots.

    Science.gov (United States)

    Stukenbrock, Eva H; Dutheil, Julien Y

    2018-03-01

    Meiotic recombination is an important driver of evolution. Variability in the intensity of recombination across chromosomes can affect sequence composition, nucleotide variation, and rates of adaptation. In many organisms, recombination events are concentrated within short segments termed recombination hotspots. The variation in recombination rate and positions of recombination hotspot can be studied using population genomics data and statistical methods. In this study, we conducted population genomics analyses to address the evolution of recombination in two closely related fungal plant pathogens: the prominent wheat pathogen Zymoseptoria tritici and a sister species infecting wild grasses Z. ardabiliae We specifically addressed whether recombination landscapes, including hotspot positions, are conserved in the two recently diverged species and if recombination contributes to rapid evolution of pathogenicity traits. We conducted a detailed simulation analysis to assess the performance of methods of recombination rate estimation based on patterns of linkage disequilibrium, in particular in the context of high nucleotide diversity. Our analyses reveal overall high recombination rates, a lack of suppressed recombination in centromeres, and significantly lower recombination rates on chromosomes that are known to be accessory. The comparison of the recombination landscapes of the two species reveals a strong correlation of recombination rate at the megabase scale, but little correlation at smaller scales. The recombination landscapes in both pathogen species are dominated by frequent recombination hotspots across the genome including coding regions, suggesting a strong impact of recombination on gene evolution. A significant but small fraction of these hotspots colocalize between the two species, suggesting that hotspot dynamics contribute to the overall pattern of fast evolving recombination in these species. Copyright © 2018 Stukenbrock and Dutheil.

  7. The Influence of Chemi-Ionization and Recombination Processes on Spectral Line Shapes in Stellar Atmospheres

    Directory of Open Access Journals (Sweden)

    Mihajlov Anatolij A.

    2011-12-01

    Full Text Available The chemi-ionization processes in atom - Rydberg atom collisions, as well as the corresponding chemi-recombination processes, are considered as factors of influence on the atom exited-state populations in weakly ionized layers of stellar atmospheres. The presented results are related to the photospheres of the Sun and some M red dwarfs, as well as weakly ionized layers of DB white dwarf atmospheres. It has been found that the mentioned chemi-ionization and recombination processes dominate over the concurrent electron-atom and electron-ion ionization and recombination processes in all parts of the considered stellar atmospheres. The obtained results demonstrate the fact that the considered processes must have significant influence on the optical properties of stellar atmospheres. It is shown that these processes and their importance for non-local thermodynamic equilibrium (non-LTE modeling of the solar atmospheres should be investigated further.

  8. Superfluid Boundary Layer.

    Science.gov (United States)

    Stagg, G W; Parker, N G; Barenghi, C F

    2017-03-31

    We model the superfluid flow of liquid helium over the rough surface of a wire (used to experimentally generate turbulence) profiled by atomic force microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that the sharpest features in the surface induce vortex nucleation both intrinsically (due to the raised local fluid velocity) and extrinsically (providing pinning sites to vortex lines aligned with the flow). Vortex interactions and reconnections contribute to form a dense turbulent layer of vortices with a nonclassical average velocity profile which continually sheds small vortex rings into the bulk. We characterize this layer for various imposed flows. As boundary layers conventionally arise from viscous forces, this result opens up new insight into the nature of superflows.

  9. Electrochemical Characterization of TiO 2 Blocking Layers for Dye-Sensitized Solar Cells

    KAUST Repository

    Kavan, Ladislav; Té treault, Nicolas; Moehl, Thomas; Grä tzel, Michael

    2014-01-01

    Thin compact layers of TiO2 are grown by thermal oxidation of Ti, by spray pyrolysis, by electrochemical deposition, and by atomic layer deposition. These layers are used in dye-sensitized solar cells to prevent recombination of electrons from

  10. Some theoretical aspects of electrostatic double layers

    International Nuclear Information System (INIS)

    Carlqvist, P.

    1978-11-01

    A review is presented of the main results of the theoretical work on electrostatic double layers. The general properties of double layers are first considered. Then the time-independent double layer is discussed. The discussion deals with the potential drop, the thickness, and some necessary criteria for the existence and stability of the layer. As a complement to the study of the timeindependent double layer a few remarks are also made upon the timedependent double layer. Finally the question of how double layers are formed and maintained is treated. Several possible formation mechanisms are considered. (author)

  11. Effects of nuclear mutations for recombination and repair functions and of caffeine on mitochondrial recombination

    International Nuclear Information System (INIS)

    Fraenkel, A.H.M.

    1974-01-01

    Studies of both prokaryotic and eukaryotic organisms indicate that pathways governing repair of damage to nuclear DNA caused by x-ray or ultraviolet irradiation overlap with those controlling recombination. Fourteen nuclear mutants of Saccharomyces cerevisiae were tested in order to determine whether these mutant genes affected mitochondrial recombination. None of the mutations studied significantly affected mitochondrial recombination. The nuclear recombination and repair pathways studied do not overlap with the nuclear pathway which controls recombination of mitochondrial DNA. A second set of experiments was designed to test the effect of caffeine on both nuclear and mitochondrial recombination in Saccharomyces cerevisiae. (U.S.)

  12. Method of forming an HTS article

    Science.gov (United States)

    Bhattacharya, Raghu N.; Zhang, Xun; Selvamanickam, Venkat

    2014-08-19

    A method of forming a superconducting article includes providing a substrate tape, forming a superconducting layer overlying the substrate tape, and depositing a capping layer overlying the superconducting layer. The capping layer includes a noble metal and has a thickness not greater than about 1.0 micron. The method further includes electrodepositing a stabilizer layer overlying the capping layer using a solution that is non-reactive to the superconducting layer. The superconducting layer has an as-formed critical current I.sub.C(AF) and a post-stabilized critical current I.sub.C(PS). The I.sub.C(PS) is at least about 95% of the I.sub.C(AF).

  13. Partial radiative recombination cross sections for excited states of hydrogen

    International Nuclear Information System (INIS)

    Fazio, P.M.

    1984-01-01

    In calculating the radiative recombination cross sections for interstellar H II regions, usually only the electric dipole term in the expansion of the interaction Hamiltonian is kept. The dipole and quadrupole transition strengths in closed analytical form are calculated here using the Coulomb wave functions because results for any electron energy and for recombination into any angular momentum state of hydrogen are needed. Several interesting effects are found. First, the transition probabilities are maximum for recombination into specific intermediate angular momentum states at low energies (w < 2eV) and where the free state angular momentum is greater than that of the bound state. Further, that specific intermediate angular momentum state depends on the kinetic energy of the free electron. This behavior is in contrast to the normal behavior of the transition strengths where recombination into s states is greatest and decreases with increasing angular momentum. Second, the quadrupole matrix elements vanish for certain velocities of the free electron. This leads to minima in the corresponding quadrupole cross sections when plotted as a function of the free electron's kinetic energy. Finally, the partial cross sections for highly excited states are greater than previously calculated because of the additional effects of the quadrupole transitions

  14. Cloning and expression of recombinant, functional ricin B chain

    International Nuclear Information System (INIS)

    Chang, M.S.; Russell, D.W.; Uhr, J.W.; Vitetta, E.S.

    1987-01-01

    The cDNA encoding the B chain of the plant toxin ricin has been cloned and expressed in monkey kidney COS-M6 cells. The recombinant B chain was detected by labeling the transfected cells with [ 35 S]methionine and [ 35 S]-cysteine and demonstrating the secretion of a protein with a M/sub r/ of 30,000-32,000 that was not present in the medium of mock-transfected COS-M6 cells. This protein was specifically immunoprecipitated by an anti-ricin or anti-B-chain antibody and the amount of recombinant B chain secreted by the COS-M6 cells was determined by a radioimmunoassay. Virtually all of the recombinant B chain formed active ricin when mixed with native A chain; it could also bind to the galactose-containing glycoprotein asialofetuin as effectively as native B chain.These results indicate that the vast majority of recombinant B chains secreted into the medium of the COS-M6 cells retain biological function

  15. Genome engineering for improved recombinant protein expression in Escherichia coli.

    Science.gov (United States)

    Mahalik, Shubhashree; Sharma, Ashish K; Mukherjee, Krishna J

    2014-12-19

    A metabolic engineering perspective which views recombinant protein expression as a multistep pathway allows us to move beyond vector design and identify the downstream rate limiting steps in expression. In E.coli these are typically at the translational level and the supply of precursors in the form of energy, amino acids and nucleotides. Further recombinant protein production triggers a global cellular stress response which feedback inhibits both growth and product formation. Countering this requires a system level analysis followed by a rational host cell engineering to sustain expression for longer time periods. Another strategy to increase protein yields could be to divert the metabolic flux away from biomass formation and towards recombinant protein production. This would require a growth stoppage mechanism which does not affect the metabolic activity of the cell or the transcriptional or translational efficiencies. Finally cells have to be designed for efficient export to prevent buildup of proteins inside the cytoplasm and also simplify downstream processing. The rational and the high throughput strategies that can be used for the construction of such improved host cell platforms for recombinant protein expression is the focus of this review.

  16. Vaccine platform recombinant measles virus.

    Science.gov (United States)

    Mühlebach, Michael D

    2017-10-01

    The classic development of vaccines is lengthy, tedious, and may not necessarily be successful as demonstrated by the case of HIV. This is especially a problem for emerging pathogens that are newly introduced into the human population and carry the inherent risk of pandemic spread in a naïve population. For such situations, a considerable number of different platform technologies are under development. These are also under development for pathogens, where directly derived vaccines are regarded as too complicated or even dangerous due to the induction of inefficient or unwanted immune responses causing considerable side-effects as for dengue virus. Among platform technologies are plasmid-based DNA vaccines, RNA replicons, single-round infectious vector particles, or replicating vaccine-based vectors encoding (a) critical antigen(s) of the target pathogens. Among the latter, recombinant measles viruses derived from vaccine strains have been tested. Measles vaccines are among the most effective and safest life-attenuated vaccines known. Therefore, the development of Schwarz-, Moraten-, or AIK-C-strain derived recombinant vaccines against a wide range of mostly viral, but also bacterial pathogens was quite straightforward. These vaccines generally induce powerful humoral and cellular immune responses in appropriate animal models, i.e., transgenic mice or non-human primates. Also in the recent first clinical phase I trial, the results have been quite encouraging. The trial indicated the expected safety and efficacy also in human patients, interestingly independent from the level of prevalent anti-measles immunity before the trial. Thereby, recombinant measles vaccines expressing additional antigens are a promising platform for future vaccines.

  17. Hydrogen Recombination Rates of Plate-type Passive Auto-catalytic Recombiner

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jongtae; Hong, Seong-Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Gun Hong [Kyungwon E-C Co., Seongnam (Korea, Republic of)

    2014-10-15

    The hydrogen mitigation system may include igniters, passive autocatalytic recombiner (PAR), and venting or dilution system. Recently PAR is commonly used as a main component of HMS in a NPP containment because of its passive nature. PARs are categorized by the shape and material of catalytic surface. Catalytic surface coated by platinum is mostly used for the hydrogen recombiners. The shapes of the catalytic surface can be grouped into plate type, honeycomb type and porous media type. Among them, the plate-type PAR is well tested by many experiments. PAR performance analysis can be approached by a multi-scale method which is composed of micro, meso and macro scales. The criterion of the scaling is the ratio of thickness of boundary layer developed on a catalytic surface to representative length of a computational domain. Mass diffusion in the boundary layer must be resolved in the micro scale analysis. In a lumped parameter (LP) analysis using a system code such as MAAP or MELCOR, the chamber of the PAR is much smaller than a computational node. The hydrogen depletion by a PAR is modeled as a source of mass and energy conservation equations. Te catalytic surface reaction of hydrogen must be modeled by a volume-averaged correlation. In this study, a micro scale analysis method is developed using libraries in OpenFOAM to evaluate a hydrogen depletion rate depending on parameters such as size and number of plates and plate arrangement. The analysis code is validated by simulating REKO-3 experiment. And hydrogen depletion analysis is conducted by changing the plate arrangement as a trial of the performance enhancement of a PAR. In this study, a numerical code for an analysis of a PAR performance in a micro scale has been developed by using OpenFOAM libraries. The physical and numerical models were validated by simulating the REKO-3 experiment. As a try to enhance the performance of the plate-type PAR, it was proposed to apply a staggered two-layer arrangement of the

  18. Hydrogen Recombination Rates of Plate-type Passive Auto-catalytic Recombiner

    International Nuclear Information System (INIS)

    Kim, Jongtae; Hong, Seong-Wan; Kim, Gun Hong

    2014-01-01

    The hydrogen mitigation system may include igniters, passive autocatalytic recombiner (PAR), and venting or dilution system. Recently PAR is commonly used as a main component of HMS in a NPP containment because of its passive nature. PARs are categorized by the shape and material of catalytic surface. Catalytic surface coated by platinum is mostly used for the hydrogen recombiners. The shapes of the catalytic surface can be grouped into plate type, honeycomb type and porous media type. Among them, the plate-type PAR is well tested by many experiments. PAR performance analysis can be approached by a multi-scale method which is composed of micro, meso and macro scales. The criterion of the scaling is the ratio of thickness of boundary layer developed on a catalytic surface to representative length of a computational domain. Mass diffusion in the boundary layer must be resolved in the micro scale analysis. In a lumped parameter (LP) analysis using a system code such as MAAP or MELCOR, the chamber of the PAR is much smaller than a computational node. The hydrogen depletion by a PAR is modeled as a source of mass and energy conservation equations. Te catalytic surface reaction of hydrogen must be modeled by a volume-averaged correlation. In this study, a micro scale analysis method is developed using libraries in OpenFOAM to evaluate a hydrogen depletion rate depending on parameters such as size and number of plates and plate arrangement. The analysis code is validated by simulating REKO-3 experiment. And hydrogen depletion analysis is conducted by changing the plate arrangement as a trial of the performance enhancement of a PAR. In this study, a numerical code for an analysis of a PAR performance in a micro scale has been developed by using OpenFOAM libraries. The physical and numerical models were validated by simulating the REKO-3 experiment. As a try to enhance the performance of the plate-type PAR, it was proposed to apply a staggered two-layer arrangement of the

  19. Die singulation method and package formed thereby

    Science.gov (United States)

    Anderson, Robert C [Tucson, AZ; Shul, Randy J [Albuquerque, NM; Clews, Peggy J [Tijeras, NM; Baker, Michael S [Albuquerque, NM; De Boer, Maarten P [Albuquerque, NM

    2012-08-07

    A method is disclosed for singulating die from a substrate having a sacrificial layer and one or more device layers, with a retainer being formed in the device layer(s) and anchored to the substrate. Deep Reactive Ion Etching (DRIE) etching of a trench through the substrate from the bottom side defines a shape for each die. A handle wafer is then attached to the bottom side of the substrate, and the sacrificial layer is etched to singulate the die and to form a frame from the retainer and the substrate. The frame and handle wafer, which retain the singulated die in place, can be attached together with a clamp or a clip and to form a package for the singulated die. One or more stops can be formed from the device layer(s) to limit a sliding motion of the singulated die.

  20. CRMAGE: CRISPR Optimized MAGE Recombineering

    DEFF Research Database (Denmark)

    Ronda, Carlotta; Pedersen, Lasse Ebdrup; Sommer, Morten Otto Alexander

    2016-01-01

    A bottleneck in metabolic engineering and systems biology approaches is the lack of efficient genome engineering technologies. Here, we combine CRISPR/Cas9 and λ Red recombineering based MAGE technology (CRMAGE) to create a highly efficient and fast method for genome engineering of Escherichia coli...... that are assembled by a USER-cloning approach enabling quick and cost efficient gRNA replacement. CRMAGE furthermore utilizes CRISPR/Cas9 for efficient plasmid curing, thereby enabling multiple engineering rounds per day. To facilitate the design process, a web-based tool was developed to predict both the λ Red...

  1. Recombination at DNA replication fork barriers is not universal and is differentially regulated by Swi1.

    Science.gov (United States)

    Pryce, David W; Ramayah, Soshila; Jaendling, Alessa; McFarlane, Ramsay J

    2009-03-24

    DNA replication stress has been implicated in the etiology of genetic diseases, including cancers. It has been proposed that genomic sites that inhibit or slow DNA replication fork progression possess recombination hotspot activity and can form potential fragile sites. Here we used the fission yeast, Schizosaccharomyces pombe, to demonstrate that hotspot activity is not a universal feature of replication fork barriers (RFBs), and we propose that most sites within the genome that form RFBs do not have recombination hotspot activity under nonstressed conditions. We further demonstrate that Swi1, the TIMELESS homologue, differentially controls the recombination potential of RFBs, switching between being a suppressor and an activator of recombination in a site-specific fashion.

  2. Atomic excitation and recombination in external fields

    International Nuclear Information System (INIS)

    Nayfeh, M.H.; Clark, C.W.

    1985-01-01

    This volume offers a timely look at Rydberg states of atoms in external fields and dielectronic recombination. Each topic provides authoritative coverage, presents a fresh account of a flourishing field of current atomic physics and introduces new opportunities for discovery and development. Topics considered include electron-atom scattering in external fields; observations of regular and irregular motion as exemplified by the quadratic zeeman effect and other systems; Rydberg atoms in external fields and the Coulomb geometry; crossed-field effects in the absorption spectrum of lithium in a magnetic field; precise studies of static electric field ionization; widths and shapes of stark resonances in sodium above the saddle point; studies of electric field effects and barium autoionizing resonances; autoionization and dielectronic recombination in plasma electric microfields; dielectronic recombination measurements on multicharged ions; merged beam studies of dielectronic recombination; Rydberg atoms and dielectronic recombination in astrophysics; and observations on dielectronic recombination

  3. Hollow fiber membranes and methods for forming same

    Science.gov (United States)

    Bhandari, Dhaval Ajit; McCloskey, Patrick Joseph; Howson, Paul Edward; Narang, Kristi Jean; Koros, William

    2016-03-22

    The invention provides improved hollow fiber membranes having at least two layers, and methods for forming the same. The methods include co-extruding a first composition, a second composition, and a third composition to form a dual layer hollow fiber membrane. The first composition includes a glassy polymer; the second composition includes a polysiloxane; and the third composition includes a bore fluid. The dual layer hollow fiber membranes include a first layer and a second layer, the first layer being a porous layer which includes the glassy polymer of the first composition, and the second layer being a polysiloxane layer which includes the polysiloxane of the second composition.

  4. Radiative and interfacial recombination in CdTe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, C. H., E-mail: craig.swartz@txstate.edu; Edirisooriya, M.; LeBlanc, E. G.; Noriega, O. C.; Jayathilaka, P. A. R. D.; Ogedengbe, O. S.; Hancock, B. L.; Holtz, M.; Myers, T. H. [Materials Science, Engineering, and Commercialization Program, Texas State University, 601 University Dr., San Marcos, Texas 78666 (United States); Zaunbrecher, K. N. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Mississippi RSF200, Golden, Colorado 80401 (United States)

    2014-12-01

    Double heterostructures (DH) were produced consisting of a CdTe film between two wide band gap barriers of CdMgTe alloy. A combined method was developed to quantify radiative and non-radiative recombination rates by examining the dependence of photoluminescence (PL) on both excitation intensity and time. The measured PL characteristics, and the interface state density extracted by modeling, indicate that the radiative efficiency of CdMgTe/CdTe DHs is comparable to that of AlGaAs/GaAs DHs, with interface state densities in the low 10{sup 10 }cm{sup −2} and carrier lifetimes as long as 240 ns. The radiative recombination coefficient of CdTe is found to be near 10{sup −10} cm{sup 3}s{sup −1}. CdTe film growth on bulk CdTe substrates resulted in a homoepitaxial interface layer with a high non-radiative recombination rate.

  5. Density dependence of dielectronic recombination in selenium

    International Nuclear Information System (INIS)

    Hagelstein, P.L.; Rosen, M.D.; Jacobs, V.L.

    1986-01-01

    Dielectronic recombination has been found to be the dominant recombination process in the determination of the ionization balance of selenium near the Ne-like sequence under conditions relevant to the exploding-foil EUV laser plasmas. The dielectronic recombination process tends to populate excited levels, and these levels in turn are more susceptible to subsequent excitation and ionization than are the ground-state ions. If one defines an effective recombination rate which includes, in addition to the primary recombination, the subsequent excitation and ionization of the additional excited-state population due to the primary recombination, then this effective recombination rate can be density-sensitive at relatively low electron density. We present results for this effective dielectronic recombination rate at an electron density of 3 x 10/sup 20/ electrons/cm 3 for recombination from Ne-like to Na-like selenium and from F-like to Ne-like selenium. In the former case, the effective recombination rate coefficient is found to be 1.8 x 10/sup -11/ cm 3 /sec at 1.0 keV, which is to be compared with the zero-density value of 2.8 x 10/sup -11/ cm 3 /sec. In the latter case (F-like to Ne-like), the effective recombination rate coefficient is found to be 1.3 x 10/sup -11/ cm 3 /sec, which is substantially reduced from the zero-density result of 3.3 x 10/sup -11/ cm 3 /sec. We have examined the effects of dielectronic recombination on the laser gain of the dominant Ne-like 3p-3s transitions and have compared our results with those presented by Whitten et al. [Phys. Rev. A 33, 2171 (1986)

  6. Layer-by-layer-assembled quantum dot multilayer sensitizers: how the number of layers affects the photovoltaic properties of one-dimensional ZnO nanowire electrodes.

    Science.gov (United States)

    Jin, Ho; Choi, Sukyung; Lim, Sang-Hoon; Rhee, Shi-Woo; Lee, Hyo Joong; Kim, Sungjee

    2014-01-13

    Layer cake: Multilayered CdSe quantum dot (QD) sensitizers are layer-by-layer assembled onto ZnO nanowires by making use of electrostatic interactions to study the effect of the layer number on the photovoltaic properties. The photovoltaic performance of QD-sensitized solar cells critically depends on this number as a result of the balance between light-harvesting efficiency and carrier-recombination probability. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Boosting water oxidation layer-by-layer.

    Science.gov (United States)

    Hidalgo-Acosta, Jonnathan C; Scanlon, Micheál D; Méndez, Manuel A; Amstutz, Véronique; Vrubel, Heron; Opallo, Marcin; Girault, Hubert H

    2016-04-07

    Electrocatalysis of water oxidation was achieved using fluorinated tin oxide (FTO) electrodes modified with layer-by-layer deposited films consisting of bilayers of negatively charged citrate-stabilized IrO2 NPs and positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer. The IrO2 NP surface coverage can be fine-tuned by controlling the number of bilayers. The IrO2 NP films were amorphous, with the NPs therein being well-dispersed and retaining their as-synthesized shape and sizes. UV/vis spectroscopic and spectro-electrochemical studies confirmed that the total surface coverage and electrochemically addressable surface coverage of IrO2 NPs increased linearly with the number of bilayers up to 10 bilayers. The voltammetry of the modified electrode was that of hydrous iridium oxide films (HIROFs) with an observed super-Nernstian pH response of the Ir(III)/Ir(IV) and Ir(IV)-Ir(IV)/Ir(IV)-Ir(V) redox transitions and Nernstian shift of the oxygen evolution onset potential. The overpotential of the oxygen evolution reaction (OER) was essentially pH independent, varying only from 0.22 V to 0.28 V (at a current density of 0.1 mA cm(-2)), moving from acidic to alkaline conditions. Bulk electrolysis experiments revealed that the IrO2/PDDA films were stable and adherent under acidic and neutral conditions but degraded in alkaline solutions. Oxygen was evolved with Faradaic efficiencies approaching 100% under acidic (pH 1) and neutral (pH 7) conditions, and 88% in alkaline solutions (pH 13). This layer-by-layer approach forms the basis of future large-scale OER electrode development using ink-jet printing technology.

  8. Recombination and population mosaic of a multifunctional viral gene, adeno-associated virus cap.

    Directory of Open Access Journals (Sweden)

    Yasuhiro Takeuchi

    Full Text Available Homologous recombination is a dominant force in evolution and results in genetic mosaics. To detect evidence of recombination events and assess the biological significance of genetic mosaics, genome sequences for various viral populations of reasonably large size are now available in the GenBank. We studied a multi-functional viral gene, the adeno-associated virus (AAV cap gene, which codes for three capsid proteins, VP1, VP2 and VP3. VP1-3 share a common C-terminal domain corresponding to VP3, which forms the viral core structure, while the VP1 unique N-terminal part contains an enzymatic domain with phospholipase A2 activity. Our recombinant detection program (RecI revealed five novel recombination events, four of which have their cross-over points in the N-terminal, VP1 and VP2 unique region. Comparison of phylogenetic trees for different cap gene regions confirmed discordant phylogenies for the recombinant sequences. Furthermore, differences in the phylogenetic tree structures for the VP1 unique (VP1u region and the rest of cap highlighted the mosaic nature of cap gene in the AAV population: two dominant forms of VP1u sequences were identified and these forms are linked to diverse sequences in the rest of cap gene. This observation together with the finding of frequent recombination in the VP1 and 2 unique regions suggests that this region is a recombination hot spot. Recombination events in this region preserve protein blocks of distinctive functions and contribute to convergence in VP1u and divergence of the rest of cap. Additionally the possible biological significance of two dominant VP1u forms is inferred.

  9. Rapid purification of recombinant histones.

    Science.gov (United States)

    Klinker, Henrike; Haas, Caroline; Harrer, Nadine; Becker, Peter B; Mueller-Planitz, Felix

    2014-01-01

    The development of methods to assemble nucleosomes from recombinant histones decades ago has transformed chromatin research. Nevertheless, nucleosome reconstitution remains time consuming to this day, not least because the four individual histones must be purified first. Here, we present a streamlined purification protocol of recombinant histones from bacteria. We termed this method "rapid histone purification" (RHP) as it circumvents isolation of inclusion bodies and thereby cuts out the most time-consuming step of traditional purification protocols. Instead of inclusion body isolation, whole cell extracts are prepared under strongly denaturing conditions that directly solubilize inclusion bodies. By ion exchange chromatography, the histones are purified from the extracts. The protocol has been successfully applied to all four canonical Drosophila and human histones. RHP histones and histones that were purified from isolated inclusion bodies had similar purities. The different purification strategies also did not impact the quality of octamers reconstituted from these histones. We expect that the RHP protocol can be readily applied to the purification of canonical histones from other species as well as the numerous histone variants.

  10. The extent and importance of intragenic recombination

    Directory of Open Access Journals (Sweden)

    de Silva Eric

    2004-11-01

    Full Text Available Abstract We have studied the recombination rate behaviour of a set of 140 genes which were investigated for their potential importance in inflammatory disease. Each gene was extensively sequenced in 24 individuals of African descent and 23 individuals of European descent, and the recombination process was studied separately in the two population samples. The results obtained from the two populations were highly correlated, suggesting that demographic bias does not affect our population genetic estimation procedure. We found evidence that levels of recombination correlate with levels of nucleotide diversity. High marker density allowed us to study recombination rate variation on a very fine spatial scale. We found that about 40 per cent of genes showed evidence of uniform recombination, while approximately 12 per cent of genes carried distinct signatures of recombination hotspots. On studying the locations of these hotspots, we found that they are not always confined to introns but can also stretch across exons. An investigation of the protein products of these genes suggested that recombination hotspots can sometimes separate exons belonging to different protein domains; however, this occurs much less frequently than might be expected based on evolutionary studies into the origins of recombination. This suggests that evolutionary analysis of the recombination process is greatly aided by considering nucleotide sequences and protein products jointly.

  11. Genetic recombination in plant-infecting messenger-sense RNA viruses: overview and research perspectives

    Directory of Open Access Journals (Sweden)

    Jozef Julian Bujarski

    2013-03-01

    Full Text Available RNA recombination is one of the driving forces of genetic variability in (+-strand RNA viruses. Various types of RNA-RNA crossovers were described including crosses between the same or different viral RNAs or between viral and cellular RNAs. Likewise, a variety of molecular mechanisms are known to support RNA recombination, such as replicative events (based on internal or end-to-end replicase switchings along with nonreplicative joining among RNA fragments of viral and/or cellular origin. Such mechanisms as RNA decay or RNA interference are responsible for RNA fragmentation and trans-esterification reactions which are likely accountable for ligation of RNA fragments. Numerous host factors were found to affect the profiles of viral RNA recombinants and significant differences in recombination frequency were observed among various RNA viruses. Comparative analyses of viral sequences allowed for the development of evolutionary models in order to explain adaptive phenotypic changes and co-evolving sites. Many questions remain to be answered by forthcoming RNA recombination research. (i How various factors modulate the ability of viral replicase to switch templates, (ii What is the intracellular location of RNA-RNA template switchings, (iii Mechanisms and factors responsible for non-replicative RNA recombination, (iv Mechanisms of integration of RNA viral sequences with cellular genomic DNA, and (v What is the role of RNA splicing and ribozyme activity. From an evolutionary stand point, it is not known how RNA viruses parasitize new host species via recombination, nor is it obvious what the contribution of RNA recombination is among other RNA modification pathways. We do not understand why the frequency of RNA recombination varies so much among RNA viruses and the status of RNA recombination as a form of sex is not well documented.

  12. Simulation of hydrogen mitigation in catalytic recombiner. Part-II: Formulation of a CFD model

    International Nuclear Information System (INIS)

    Prabhudharwadkar, Deoras M.; Iyer, Kannan N.

    2011-01-01

    Research highlights: → Hydrogen transport in containment with recombiners is a multi-scale problem. → A novel methodology worked out to lump the recombiner characteristics. → Results obtained using commercial code FLUENT are cast in the form of correlations. → Hence, coarse grids can obtain accurate distribution of H 2 in containment. → Satisfactory working of the methodology is clearly demonstrated. - Abstract: This paper aims at formulation of a model compatible with CFD code to simulate hydrogen distribution and mitigation using a Passive Catalytic Recombiner in the Nuclear power plant containments. The catalytic recombiner is much smaller in size compared to the containment compartments. In order to fully resolve the recombination processes during the containment simulations, it requires the geometric details of the recombiner to be modelled and a very fine mesh size inside the recombiner channels. This component when integrated with containment mixing calculations would result in a large number of mesh elements which may take large computational times to solve the problem. This paper describes a method to resolve this simulation difficulty. In this exercise, the catalytic recombiner alone was first modelled in detail using the best suited option to describe the reaction rate. A detailed parametric study was conducted, from which correlations for the heat of reaction (hence the rate of reaction) and the heat transfer coefficient were obtained. These correlations were then used to model the recombiner channels as single computational cells providing necessary volumetric sources/sinks to the energy and species transport equations. This avoids full resolution of these channels, thereby allowing larger mesh size in the recombiners. The above mentioned method was successfully validated using both steady state and transient test problems and the results indicate very satisfactory modelling of the component.

  13. Genetic recombination in plant-infecting messenger-sense RNA viruses: overview and research perspectives.

    Science.gov (United States)

    Bujarski, Jozef J

    2013-01-01

    RNA recombination is one of the driving forces of genetic variability in (+)-strand RNA viruses. Various types of RNA-RNA crossovers were described including crosses between the same or different viral RNAs or between viral and cellular RNAs. Likewise, a variety of molecular mechanisms are known to support RNA recombination, such as replicative events (based on internal or end-to-end replicase switchings) along with non-replicative joining among RNA fragments of viral and/or cellular origin. Such mechanisms as RNA decay or RNA interference are responsible for RNA fragmentation and trans-esterification reactions which are likely accountable for ligation of RNA fragments. Numerous host factors were found to affect the profiles of viral RNA recombinants and significant differences in recombination frequency were observed among various RNA viruses. Comparative analyses of viral sequences allowed for the development of evolutionary models in order to explain adaptive phenotypic changes and co-evolving sites. Many questions remain to be answered by forthcoming RNA recombination research. (1) How various factors modulate the ability of viral replicase to switch templates, (2) What is the intracellular location of RNA-RNA template switchings, (3) Mechanisms and factors responsible for non-replicative RNA recombination, (4) Mechanisms of integration of RNA viral sequences with cellular genomic DNA, and (5) What is the role of RNA splicing and ribozyme activity. From an evolutionary stand point, it is not known how RNA viruses parasitize new host species via recombination, nor is it obvious what the contribution of RNA recombination is among other RNA modification pathways. We do not understand why the frequency of RNA recombination varies so much among RNA viruses and the status of RNA recombination as a form of sex is not well documented.

  14. Organic photovoltaic cells utilizing ultrathin sensitizing layer

    Science.gov (United States)

    Rand, Barry P [Princeton, NJ; Forrest, Stephen R [Princeton, NJ

    2011-05-24

    A photosensitive device includes a series of organic photoactive layers disposed between two electrodes. Each layer in the series is in direct contact with a next layer in the series. The series is arranged to form at least one donor-acceptor heterojunction, and includes a first organic photoactive layer comprising a first host material serving as a donor, a thin second organic photoactive layer comprising a second host material disposed between the first and a third organic photoactive layer, and the third organic photoactive layer comprising a third host material serving as an acceptor. The first, second, and third host materials are different. The thin second layer serves as an acceptor relative to the first layer or as a donor relative to the third layer.

  15. Single-crystal micromachining using multiple fusion-bonded layers

    Science.gov (United States)

    Brown, Alan; O'Neill, Garry; Blackstone, Scott C.

    2000-08-01

    Multi-layer structures have been fabricated using Fusion bonding. The paper shows void free layers of between 2 and 100 microns that have been bonded to form multi-layer structures. Silicon layers have been bonded both with and without interfacial oxide layers.

  16. Experimental evidence that RNA recombination occurs in the Japanese encephalitis virus

    International Nuclear Information System (INIS)

    Chuang, C.-K.; Chen, W.-J.

    2009-01-01

    Due to the lack of a proofreading function and error-repairing ability of genomic RNA, accumulated mutations are known to be a force driving viral evolution in the genus Flavivirus, including the Japanese encephalitis (JE) virus. Based on sequencing data, RNA recombination was recently postulated to be another factor associated with genomic variations in these viruses. We herein provide experimental evidence to demonstrate the occurrence of RNA recombination in the JE virus using two local pure clones (T1P1-S1 and CJN-S1) respectively derived from the local strains, T1P1 and CJN. Based on results from a restriction fragment length polymorphism (RFLP) assay on the C/preM junction comprising a fragment of 868 nucleotides (nt 10-877), the recombinant progeny virus was primarily formed in BHK-21 cells that had been co-infected with the two clones used in this study. Nine of 20 recombinant forms of the JE virus had a crossover in the nt 123-323 region. Sequencing data derived from these recombinants revealed that no nucleotide deletion or insertion occurred in this region favoring crossovers, indicating that precisely, not aberrantly, homologous recombination was involved. With site-directed mutagenesis, three stem-loop secondary structures were destabilized and re-stabilized in sequence, leading to changes in the frequency of recombination. This suggests that the conformation, not the free energy, of the secondary structure is important in modulating RNA recombination of the virus. It was concluded that because RNA recombination generates genetic diversity in the JE virus, this must be considered particularly in studies of viral evolution, epidemiology, and possible vaccine safety.

  17. Isolation of recombinant antibodies directed against surface proteins of Clostridium difficile.

    Science.gov (United States)

    Shirvan, Ali Nazari; Aitken, Robert

    2016-01-01

    Clostridium difficile has emerged as an increasingly important nosocomial pathogen and the prime causative agent of antibiotic-associated diarrhoea and pseudomembranous colitis in humans. In addition to toxins A and B, immunological studies using antisera from patients infected with C. difficile have shown that a number of other bacterial factors contribute to the pathogenesis, including surface proteins, which are responsible for adhesion, motility and other interactions with the human host. In this study, various clostridial targets, including FliC, FliD and cell wall protein 66, were expressed and purified. Phage antibody display yielded a large panel of specific recombinant antibodies, which were expressed, purified and characterised. Reactions of the recombinant antibodies with their targets were detected by enzyme-linked immunosorbent assay; and Western blotting suggested that linear rather than conformational epitopes were recognised. Binding of the recombinant antibodies to surface-layer proteins and their components showed strain specificity, with good recognition of proteins from C. difficile 630. However, no reaction was observed for strain R20291-a representative of the 027 ribotype. Binding of the recombinant antibodies to C. difficile M120 extracts indicated that a component of a surface-layer protein of this strain might possess immunoglobulin-binding activities. The recombinant antibodies against FliC and FliD proteins were able to inhibit bacterial motility. Copyright © 2016. Published by Elsevier Editora Ltda.

  18. Ion-electron recombination in merged-beams experiments

    International Nuclear Information System (INIS)

    Schmidt, H.T.

    1994-01-01

    In the present thesis, studies of recombination processes applying the technique of merged beams of fast ions and electrons are described. The main advantage of this technique is that the low relative velocity of ions and electrons necessary for these investigations can be achieved, at the same time as the velocity of the ions relative to the molecules of the residual gas is high. The high ion velocity leads to a very low reaction cross section for the leading contribution to the background signal, the capture of electrons in collisions with residual gas molecules. The experimental technique is described, emphasizing the electron beam velocity distribution and its relation to the energy resolution of the experiments. The presentation of the process of electron cooling is aimed at introducing this process as a tool for merged-beams experiments in storage rings rather than investigating the process itself. The non-resonant process of radiative recombination for non-fully stripped ions, showing evidence of incomplete screening is presented. Experimental investigation of dielectronic recombination is presented. Results of measurements of this process for He-like ions form the Aarhus single-pass experiment and the Heidelberg storage ring experiment are compared. Recombination is reduced from being the aim of the investigation to being a tool for high-precision measurements of the lifetimes of the 1s2s 3 S metastable states of HE-like ions of boron, carbon, and nitrogen, performed at the Heidelberg storage ring. The experiment is concerned with the process of dissociative recombination of molecular hydrogen ions. The discussion of this experiment emphasizes the distribution of population on the different vibrational levels of the ions in the initial state. In particular, a laser photo-dissociation technique was introduced to reduce the number of initial levels in the experiment. (EG) 24 refs

  19. Stability of diffusion flame formed in a laminar flat plate boundary layer. Effect of fuel dilution; Soryu heiban kyokai sonai ni keiseisareru kakusan kaen no anteisei. Nenryo kishaku no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, M [National Institute for Resources and Environment, Tsukuba (Japan); Ueda, T; Mizumoto, M [Keio University, Tokyo (Japan). Faculty of Science and Technology; Amari, T [Keio University, Tokyo (Japan)

    1998-10-25

    A stability limit of the diffusion flame with fuel injection from a porous wall in a laminar flat plate boundary layer is measured as functions of fuel (CH4) concentration of CH4/N2 injectant mixture ({chi}) and its injection velocity (v). The free stream velocity (U{infinity}) is set as 0.6 m/s. The thermal condition at the wall is controlled by setting temperature at the upstream end of the porous wall as a reference temperature. When v >20 mm/s, the flame becomes unstable with the separation of leading flame edge with decreasing {chi}. The value of {chi} at the stability limit is constant without regard to v as long as the wall temperature is kept constant. As the wall temperature is decreased the value of {chi} increases. The separation is supposed to take place as a result of the limit of the reaction rate. When v <20 mm/s, the flame becomes unstable with the oscillation. The value of {chi} at the stability limit increases drastically with decreasing v. The oscillation takes place mainly due to the repeat of the extinction due to heat loss to the wall and the flame propagation in the combustible layer. 10 refs., 8 figs., 1 tab.

  20. Layered structure in core–shell silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Van Tuan, Pham [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam); Anh Tuan, Chu; Thanh Thuy, Tran; Binh Nam, Vu [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet Street, Hanoi 10000 (Viet Nam); Toan Thang, Pham [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam); Hong Duong, Pham, E-mail: duongphamhong@yahoo.com [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet Street, Hanoi 10000 (Viet Nam); Thanh Huy, Pham, E-mail: huy.phamthanh@hust.edu.vn [Advanced Institute for Science and Technology (AIST) and International Training Institute for Materials Science Hanoi University of Science and Technology, 01 Dai Co Viet Street,Hanoi 10000,Vietnam (Viet Nam)

    2014-10-15

    Silicon nanowires (NWs) with core–shell structures were prepared using the Vapor–Liquid–Solid (VLS) method. The wires have lengths of several hundreds of nanometers and diameters in the range of 30–50 nm. Generally, these wires are too large to exhibit the quantum confinement effect of excitons in Si nanocrystals. However, the photoluminescence (PL) and Raman spectra are similar to those of nanocrystalline silicon embedded in a SiO{sub 2} matrix, in which the recombination of quantum-confined excitons plays an important role. This effect occurs only when the average size of the silicon nanocrystals is smaller than 5 nm. To understand this discrepancy, TEM images of nanowires were obtained and analyzed. The results revealed that the cores of wires have a layered Si/SiO{sub 2} structure, in which the thickness of each layer is much smaller than its diameter. The temperature dependence of the PL intensity was recorded from 11 to 300 K; the result is in good agreement with a model that takes into account the energy splitting between the excitonic singlet and triplet levels. - Highlights: • The cores of the Si NWs have a layered Si/SiO{sub 2} structure. • The Si NWs were formed due to the phase separation of Si and SiO{sub 2} and the partial oxidization by residual oxygen. • Two processes, the reaction of Si and oxygen atoms and the combination between Si atoms, occur simultaneously. • The formation of the layered structures is associated with the self-limiting oxidation phenomenon in Si nanostructures.

  1. Reflective article having a sacrificial cathodic layer

    Science.gov (United States)

    Kabagambe, Benjamin; Buchanan, Michael J.; Scott, Matthew S.; Rearick, Brian K.; Medwick, Paul A.; McCamy, James W.

    2017-09-12

    The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formed from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.

  2. Modification of porosity in the catalyst layer of membrane electrode assemblies using pore-forming agents; Modificacion de la porosidad en la capa catalitica de ensambles membrana-electrodo empleando agentes formadores de poros

    Energy Technology Data Exchange (ETDEWEB)

    Flores Hernandez, J. Roberto [Instituto de Investigaciones Electricas Cuernavaca, Morelos (Mexico)] e-mail: jrflores@iie.org.mx; Reyes, Brenda [UNAM. Facultad de Quimica, Mexico D.F. (Mexico); Barbosa P., Romeli [Centro de Investigacion en Energia, UNAM, Temixco, Morelos (Mexico); Cano Castillo, Ulises; Albarran, Lorena [Instituto de Investigaciones Electricas Cuernavaca, Morelos (Mexico)

    2009-09-15

    Membrane electrode assemblies (MEA) are the most important part of PEM fuel cells since their interface results in the electrochemical reactions that make the generation of electricity possible. The MEA is composed of a proton exchange membrane, both sides of which are impregnated with a catalyst layer, normally of carbon-supported platinum. Depending on the technique used for its fabrication (atomization, serigraphy, brush methods, chemical reduction, etc.), the properties of the MEA can be different in terms of porosity, distribution of the catalyst, thickness and structure of the catalyst layer, and the quality of the union between the catalyst layer and the membrane, etc. Currently, the porosity of the electrodes is generated by isopropanol evaporation (solvent used in the dye) during the fabrication process conducted in the Instituto de Investigaciones Electricas (IIE). This document presents the results obtained from adding a porous agent to the catalytic dye base composition used in the fabrication of MEA at the IIE. [Spanish] Los Ensambles Membrana-Electrodo (MEA's) son la parte mas importante en las celdas de combustibles tipo PEM, ya que en su interfaz se llevan a cabo las reacciones electroquimicas que hacen posible la generacion de electricidad. El MEA esta compuesto de una membrana de intercambio protonico a la cual se le impregna en ambos lados una capa catalitica normalmente de platino soportado en carbon. Dependiendo de la tecnica empleada en su fabricacion (atomizado, serigrafia, brocha, reduccion quimica, etc.), las propiedades del MEA pueden ser diferentes en cuanto a porosidad, distribucion del catalizador, grosor y estructura de la capa catalitica, asi como la calidad de la union entre la capa catalizadora y la membrana, etc. Actualmente, la porosidad de los electrodos es generada por la evaporacion del isopropanol (solvente utilizado en la tinta) durante el proceso de fabricacion que se realiza en el Instituto de Investigaciones

  3. Fabrication of CuInS2-sensitized solar cells via an improved SILAR process and its interface electron recombination.

    Science.gov (United States)

    Xu, Xueqing; Wan, Qingcui; Luan, Chunyan; Mei, Fengjiao; Zhao, Qian; An, Ping; Liang, Zhurong; Xu, Gang; Zapien, Juan Antonio

    2013-11-13

    Tetragonal CuInS2 (CIS) has been successfully deposited onto mesoporous TiO2 films by in-sequence growth of InxS and CuyS via a successive ionic layer absorption and reaction (SILAR) process and postdeposition annealing in sulfur ambiance. X-ray diffraction and Raman measurements showed that the obtained tetragonal CIS consisted of a chalcopyrite phase and Cu-Au ordering, which related with the antisite defect states. For a fixed Cu-S deposition cycle, an interface layer of β-In2S3 formed at the TiO2/CIS interface with suitable excess deposition of In-S. In the meantime, the content of the Cu-Au ordering phase decreased to a reasonable level. These facts resulted in the retardance of electron recombination in the cells, which is proposed to be dominated by electron transfer from the conduction band of TiO2 to the unoccupied defect states in CIS via exponentially distributed surface states. As a result, a relatively high efficiency of ~0.92% (V(oc) = 0.35 V, J(sc) = 8.49 mA cm(-2), and FF = 0.31) has been obtained. Last, but not least, with an overloading of the sensitizers, a decrease in the interface area between the sensitized TiO2 and electrolytes resulted in deceleration of hole extraction from CIS to the electrolytes, leading to a decrease in the fill factor of the solar cells. It is indicated that the unoccupied states in CIS with energy levels below EF0 of the TiO2 films play an important role in the interface electron recombination at low potentials and has a great influence on the fill factor of the solar cells.

  4. Virtual-bound, filamentary and layered states in a box-shaped quantum dot of square potential form the exact numerical solution of the effective mass Schrödinger equation

    Energy Technology Data Exchange (ETDEWEB)

    Luque, A., E-mail: a.luque@upm.es [Instituto de Energía Solar, Universidad Politécnica de Madrid (Spain); Mellor, A.; Tobías, I.; Antolín, E.; Linares, P.G.; Ramiro, I.; Martí, A. [Instituto de Energía Solar, Universidad Politécnica de Madrid (Spain)

    2013-03-15

    The effective mass Schrödinger equation of a QD of parallelepipedic shape with a square potential well is solved by diagonalizing the exact Hamiltonian matrix developed in a basis of separation-of-variables wavefunctions. The expected below bandgap bound states are found not to differ very much from the former approximate calculations. In addition, the presence of bound states within the conduction band is confirmed. Furthermore, filamentary states bounded in two dimensions and extended in one dimension and layered states with only one dimension bounded, all within the conduction band—which are similar to those originated in quantum wires and quantum wells—coexist with the ordinary continuum spectrum of plane waves. All these subtleties are absent in spherically shaped quantum dots, often used for modeling.

  5. Posttranslational modifications in human plasma MBL and human recombinant MBL

    DEFF Research Database (Denmark)

    Jensen, Pia Hønnerup; Laursen, Inga; Matthiesen, Finn

    2007-01-01

    the intact protein in its active conformation. For the first time, positions and occupation frequency of partial hydroxylations and partial glycosylations are reported in MBL. Hydroxylation and glycosylation patterns of both recombinant and plasma derived MBL were determined, using a combination of mass......Mannan-binding lectin (MBL) is a complex serum protein that plays an important role in innate immunity. In addition to assuming several different oligomeric forms, the polypeptide itself is highly heterogeneous. This heterogeneity is due to post-translational modifications, which help to stabilize......(202)) was modified in trace amounts to dehydroalanine, as detected by a 34 Da mass loss. This impairs the formation of a disulphide bond in the carbohydrate recognition domain. The dehydroalanine was identified in similar small amounts in both recombinant and plasma-derived MBL....

  6. Generation of Recombinant Ebola Viruses Using Reverse Genetics.

    Science.gov (United States)

    Groseth, Allison

    2017-01-01

    Reverse genetics systems encompass a wide array of tools aimed at recapitulating some or all of the virus life cycle. In their most complete form, full-length clone systems allow us to use plasmid-encoded versions of the ribonucleoprotein (RNP) components to initiate the transcription and replication of a plasmid-encoded version of the complete viral genome, thereby initiating the complete virus life cycle and resulting in infectious virus. As such this approach is ideal for the generation of tailor-made recombinant filoviruses, which can be used to study virus biology. In addition, the generation of tagged and particularly fluorescent or luminescent viruses can be applied as tools for both diagnostic applications and for screening to identify novel countermeasures. Here we describe the generation and basic characterization of recombinant Ebola viruses rescued from cloned cDNA using a T7-driven system.

  7. Transfer line from the PSB to the PS (recombination)

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    After sequential ejection of 5 bunches from each of the 4 rings of the Booster (originally 800 MeV, now 1.4 GeV), the 4 batches are brought to the same vertical level, so as to form a string of 20 bunches, filling the circumference of the PS. This vertical "recombination" is performed in the transfer line, using vertical bending magnets, septa and kickers. Here we see the section where the beam from ring 4 (the top one) is brought down to the level of ring 3, and the beam from ring 1 up to the level of ring 2. Further downstream (to the right, outside this picture), level 2 is brought up to level 3, identical to that of the PS. After this original recombination scheme, other ways of combining the 4 beams, vertically and/or longitudinally, were developed and used in operation.

  8. Electron-ion recombination at low energy

    International Nuclear Information System (INIS)

    Andersen, L.H.

    1993-01-01

    The work is based on results obtained with a merged-beams experiment. A beam of electronics with a well characterized density and energy distribution was merged with a fast, monoenergetic ion beam. Results have been obtained for radiative recombination and dielectronic recombination at low relative energies (0 to ∼70eV). The obtained energy resolution was improved by about a factor of 30. High vacuum technology was used to suppress interactions with electrons from the environments. The velocity distribution of the electron beam was determined. State-selective dielectronic-recombination measurements were performable. Recombination processes were studied. The theoretical background for radiative recombination and Kramers' theory are reviewed. The quantum mechanical result and its relation to the semiclassical theory is discussed. Radiative recombination was also measured with several different non-bare ions, and the applicability of the semiclassical theory to non-bare ions was investigated. The use of an effective charge is discussed. For dielectronic recombination, the standard theoretical approach in the isolated resonance and independent-processes approximation is debated. The applicability of this method was tested. The theory was able to reproduce most of the experimental data except when the recombination process was sensitive to couplings between different electronic configurations. The influence of external perturbing electrostatic fields is discussed. (AB) (31 refs.)

  9. Recombination rate plasticity: revealing mechanisms by design

    Science.gov (United States)

    Sefick, Stephen; Rushton, Chase

    2017-01-01

    For over a century, scientists have known that meiotic recombination rates can vary considerably among individuals, and that environmental conditions can modify recombination rates relative to the background. A variety of external and intrinsic factors such as temperature, age, sex and starvation can elicit ‘plastic’ responses in recombination rate. The influence of recombination rate plasticity on genetic diversity of the next generation has interesting and important implications for how populations evolve. Further, many questions remain regarding the mechanisms and molecular processes that contribute to recombination rate plasticity. Here, we review 100 years of experimental work on recombination rate plasticity conducted in Drosophila melanogaster. We categorize this work into four major classes of experimental designs, which we describe via classic studies in D. melanogaster. Based on these studies, we highlight molecular mechanisms that are supported by experimental results and relate these findings to studies in other systems. We synthesize lessons learned from this model system into experimental guidelines for using recent advances in genotyping technologies, to study recombination rate plasticity in non-model organisms. Specifically, we recommend (1) using fine-scale genome-wide markers, (2) collecting time-course data, (3) including crossover distribution measurements, and (4) using mixed effects models to analyse results. To illustrate this approach, we present an application adhering to these guidelines from empirical work we conducted in Drosophila pseudoobscura. This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’. PMID:29109222

  10. Electron-ion recombination in merged beams

    International Nuclear Information System (INIS)

    Wolf, A.; Habs, D.; Lampert, A.; Neumann, R.; Schramm, U.; Schuessler, T.; Schwalm, D.

    1993-01-01

    Detailed studies of recombination processes between electrons and highly charged ions have become possible by recent improvements of merged-beams experiments. We discuss in particular measurements with stored cooled ion beams at the Test Storage Ring (TSR) in Heidelberg. The cross section of dielectronic recombination was measured with high energy resolution for few-electron systems up to the nuclear charge of Cu at a relative energy up to 2.6 keV. At low energy (∼0.1 eV) total recombination rates of several ions were measured and compared with calculated radiative recombination rates. Laser-stimulated recombination of protons and of C 6+ ions was investigated as a function of the photon energy using visible radiation. Both the total recombination rates and the stimulated recombination spectra indicate that in spite of the short interaction time in merged beams, also collisional capture of electrons into weakly bound levels (related to three-body recombination) could be important

  11. Electronic recombination in some physics problems

    International Nuclear Information System (INIS)

    Guzman, O.

    1988-01-01

    This work is related to calculations of electronic recombination rates, as a function of electronic density, electronic temperature, and ion nuclear charge. Recombination times can be calculated and compared to cooling time, in cooling processes of ion beans by electrons from storage rings. (A.C.A.S.) [pt

  12. Generation of Modified Pestiviruses by Targeted Recombination

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Bruun; Friis, Martin Barfred; Risager, Peter Christian

    involves targeted modification of viral cDNA genomes, cloned within BACs, by Red/ET recombination-mediated mutagenesis in E.coli DH10B cells. Using recombination-mediated mutagenesis for the targeted design, the work can be expedited and focused in principal on any sequence within the viral genome...

  13. Cell biology of homologous recombination in yeast

    DEFF Research Database (Denmark)

    Eckert-Boulet, Nadine Valerie; Rothstein, Rodney; Lisby, Michael

    2011-01-01

    Homologous recombination is an important pathway for error-free repair of DNA lesions, such as single- and double-strand breaks, and for rescue of collapsed replication forks. Here, we describe protocols for live cell imaging of single-lesion recombination events in the yeast Saccharomyces...

  14. Recombinant Vaccinia Virus: Immunization against Multiple Pathogens

    Science.gov (United States)

    Perkus, Marion E.; Piccini, Antonia; Lipinskas, Bernard R.; Paoletti, Enzo

    1985-09-01

    The coding sequences for the hepatitis B virus surface antigen, the herpes simplex virus glycoprotein D, and the influenza virus hemagglutinin were inserted into a single vaccinia virus genome. Rabbits inoculated intravenously or intradermally with this polyvalent vaccinia virus recombinant produced antibodies reactive to all three authentic foreign antigens. In addition, the feasibility of multiple rounds of vaccination with recombinant vaccinia virus was demonstrated.

  15. Recombinant organisms for production of industrial products

    OpenAIRE

    Adrio, Jose-Luis; Demain, Arnold L

    2009-01-01

    A revolution in industrial microbiology was sparked by the discoveries of ther double-stranded structure of DNA and the development of recombinant DNA technology. Traditional industrial microbiology was merged with molecular biology to yield improved recombinant processes for the industrial production of primary and secondary metabolites, protein biopharmaceuticals and industrial enzymes. Novel genetic techniques such as metabolic engineering, combinatorial biosynthesis and molecular breeding...

  16. Contrasting roles of interallelic recombination at the HLA-A and HLA-B loci

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, A.L.; Hughes, M.K. (Pennsylvania State Univ., University Park (United States)); Watkins, D.I. (Univ. of Wisconsin, Madison (United States))

    1993-03-01

    A statistical study of DNA sequences of alleles at the highly polymorphic class I MHC loci of humans, HLA-A and HLA-B, showed evidence of both large-scale recombination events(involving recombination of exons 1-2 of one allele with exons 3-8 of another) and small scale recombination events (involving apparent exchange of short DNA segments). The latter events occurred disproportionately in the region of the gene encoding the antigen recognition site (ARS) of the class I molecule. Furthermore, they involved the ARS codons which are under the strongest selection favoring allelic diversity at the amino acid level. Thus, the frequency of recombinant alleles appears to have been increased by some form of balancing selection (such as overdominant selection) favoring heterozygosity in the ARS. These analyses also revealed a striking difference between the A and B loci. Recombination events appear to have occurred about twice as frequently at the B locus, and recombinants at the B locus were significantly more likely to affect polymorphic sites in the ARS. At the A locus, there are well-defined allelic lineages that have persisted since prior to the human-chimpanzee divergence; but at the B locus, there is no evidence for such long-lasting allelic lineages. Thus, relatively frequent interallelic recombination has apparently been a feature of the long-term evolution of the B locus but not of the A locus. 45 refs., 4 figs., 5 tabs.

  17. Molecular requirements for radiation-activated recombination

    International Nuclear Information System (INIS)

    Stevens, Craig W.; Zeng Ming; Stamato, Thomas; Cerniglia, George

    1997-01-01

    Purpose/Objective: The major stumbling block to successful gene therapy today is poor gene transfer. We hypothesized that ionizing radiation might activate cellular recombination, and so improve stable gene transfer. We further hypothesized that known DNA-damage-repair proteins might also be important in radiation-activated recombination. Materials and Methods: The effect of irradiation on stable gene transfer efficiency was determined in human (A549 and 39F) and rodent (NIH/3T3) cell lines. Continuous low dose rate and multiple radiation fractions were also tested. Nuclear extracts were made and the effect of irradiation on inter-plasmid recombination/ligation determined. Multiple DNA damage-repair deficient cell lines were tested for radiation-activated recombination. Results: A significant radiation dose-dependent improvement in stable plasmid transfection (by as much as 1300 fold) is demonstrated in neoplastic and primary cells. An improvement in transient plasmid transfection is also seen, with as much as 85% of cells transiently expressing b-galactosidase (20-50 fold improvement). Stable transfection is only improved for linearized or nicked plasmids. Cells have improved gene transfer for at least 96 hours after irradiation. Both fractionated and continuous low dose rate irradiation are effective at improving stable gene transfer in mammalian cells, thus making relatively high radiation dose delivery clinically feasible. Inter-plasmid recombination is radiation dose dependent in nuclear extract assays, and the type of overhang (3', 5' or blunt end) significantly affects recombination efficiency and the type of product. The most common end-joining activity involves filling-in of the overhang followed by blunt end ligation. Adenovirus is a linear, double stranded DNA virus. We demonstrate that adenoviral infection efficiency is increased by irradiation. The duration of transgene expression is lengthened because the virus integrates with high efficiency (∼10

  18. RNAi and heterochromatin repress centromeric meiotic recombination

    DEFF Research Database (Denmark)

    Ellermeier, Chad; Higuchi, Emily C; Phadnis, Naina

    2010-01-01

    During meiosis, the formation of viable haploid gametes from diploid precursors requires that each homologous chromosome pair be properly segregated to produce an exact haploid set of chromosomes. Genetic recombination, which provides a physical connection between homologous chromosomes, is essen......During meiosis, the formation of viable haploid gametes from diploid precursors requires that each homologous chromosome pair be properly segregated to produce an exact haploid set of chromosomes. Genetic recombination, which provides a physical connection between homologous chromosomes....... Surprisingly, one mutant derepressed for recombination in the heterochromatic mating-type region during meiosis and several mutants derepressed for centromeric gene expression during mitotic growth are not derepressed for centromeric recombination during meiosis. These results reveal a complex relation between...... types of repression by heterochromatin. Our results also reveal a previously undemonstrated role for RNAi and heterochromatin in the repression of meiotic centromeric recombination and, potentially, in the prevention of birth defects by maintenance of proper chromosome segregation during meiosis....

  19. BIOTECHNOLOGY OF RECOMBINANT HORMONES IN DOPING

    Directory of Open Access Journals (Sweden)

    Biljana Vitošević

    2011-09-01

    Full Text Available Recombinant DNA technology has allowed rapid progress in creating biosynthetic gene products for the treatment of many diseases. In this way it can produce large amounts of hormone, which is intended for the treatment of many pathological conditions. Recombinant hormones that are commonly used are insulin, growth hormone and erythropoietin. Precisely because of the availability of these recombinant hormones, it started their abuse by athletes. Experiments in animal models confirmed the potential effects of some of these hormones in increasing physical abilities, which attracted the attention of athletes who push the limits of their competitive capability by such manipulation. The risks of the use of recombinant hormones in doping include serious consequences for the health of athletes. Methods of detection of endogenous hormones from recombined based on the use of a monoclonal antibodies, capillary zone electrophoresis and protein biomarkers

  20. Effects of UV radiation on genetic recombination

    International Nuclear Information System (INIS)

    Vlahovic, K.; Zahradka, D.; Petranovic, M.; Petranovic, D.

    1996-01-01

    We have used the model consisting of Escherichia coli cells and l phage to study the effects of UV radiation on genetic recombination. We found two radiation induced processes that reduce or inhibit genetic recombination. One such process leads to the inability of prophage to excise itself from the irradiated bacterial chromosome by the site-specific recombination. The other process was shown to inhibit a type of general recombination by which the prophage transfers one of its genetic markers to the infecting homologous phage. Loss of the prophage ability to take part in both site-specific and general recombination was shown to develop in recB + but not in recB cells. From this we infer that the loss of prophage recombinogenicity in irradiated cells is a consequence of one process in which RecBCD enzyme (the product of recB, recC and recD genes) plays an essential role. (author)

  1. 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

  2. Containment air circulation for optimal hydrogen recombination

    International Nuclear Information System (INIS)

    Spinks, N.; Krause, M.

    1997-01-01

    An accepted first-line defense for hydrogen mitigation is to design for the hydrogen to be rapidly mixed with the containment atmosphere and diluted to below flammability concentrations. Then, as hydrogen continues to be produced in the longer term, recombiners can be used to remove hydrogen: recombiners can be located in forced-air ducts or passive recombiners can be distributed within containment and the heat of recombination used to promote local air circulation. However, this principle does not eliminate the possibility of high hydrogen concentrations at locations removed from the recombiners. An improvement on this strategy is to arrange for a specific, buoyancy-driven, overall circulation of the containment atmosphere such that the recombiners can be located within the recirculation flow, immediately downstream of the hydrogen source. This would make the mixing process more predictable and solve the mass-transfer problem associated with distributed recombiners. Ideally, the recombiners would be located just above the hydrogen source so that the heat of recombination would assist the overall circulation. In this way, the hydrogen would be removed as close as possible to the source, thereby minimizing the amount of hydrogen immediately downstream of the source and reducing the hydrogen concentration to acceptable levels at other locations. Such a strategy requires the containment volume to be divided into an upflow path, past the hydrogen source and the recombiner, and a downflow path to complete the circuit. The flow could be generated actively using fans or passively using buoyancy forces arising from the difference in density of gases in the upfiow and downflow paths; the gases in the downflow path being cooled at an elevated heat sink. (author)

  3. Dark current of organic heterostructure devices with insulating spacer layers

    Science.gov (United States)

    Yin, Sun; Nie, Wanyi; Mohite, Aditya D.; Saxena, Avadh; Smith, Darryl L.; Ruden, P. Paul

    2015-03-01

    The dark current density at fixed voltage bias in donor/acceptor organic planar heterostructure devices can either increase or decrease when an insulating spacer layer is added between the donor and acceptor layers. The dominant current flow process in these systems involves the formation and subsequent recombination of an interfacial exciplex state. If the exciplex formation rate limits current flow, the insulating interface layer can increase dark current whereas, if the exciplex recombination rate limits current flow, the insulating interface layer decreases dark current. We present a device model to describe this behavior and illustrate it experimentally for various donor/acceptor systems, e.g. P3HT/LiF/C60.

  4. The unconventional xer recombination machinery of Streptococci/Lactococci

    NARCIS (Netherlands)

    Le Bourgeois, Pascal; Bugarel, Marie; Campo, Nathalie; Daveran-Mingot, Marie-Line; Labonte, Jessica; Lanfranchi, Daniel; Lautier, Thomas; Pages, Carine; Ritzenthaler, Paul

    Homologous recombination between circular sister chromosomes during DNA replication in bacteria can generate chromosome dimers that must be resolved into monomers prior to cell division. In Escherichia coli, dimer resolution is achieved by site-specific recombination, Xer recombination, involving

  5. The double layers in the plasma sheet boundary layer during magnetic reconnection

    Science.gov (United States)

    Guo, J.; Yu, B.

    2014-11-01

    We studied the evolutions of double layers which appear after the magnetic reconnection through two-dimensional electromagnetic particle-in-cell simulation. The simulation results show that the double layers are formed in the plasma sheet boundary layer after magnetic reconnection. At first, the double layers which have unipolar structures are formed. And then the double layers turn into bipolar structures, which will couple with another new weak bipolar structure. Thus a new double layer or tripolar structure comes into being. The double layers found in our work are about several ten Debye lengths, which accords with the observation results. It is suggested that the electron beam formed during the magnetic reconnection is responsible for the production of the double layers.

  6. Enhancing the performance of blue GaN-based light emitting diodes with carrier concentration adjusting layer

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yao; Huang, Yang; Wang, Junxi; Wang, Guohong [R& D Center for Semiconductor Lighting, Chinese Academy of Sciences, Beijing 100083,P. R. China (China); Liu, Zhiqiang, E-mail: lzq@semi.ac.cn, E-mail: spring@semi.ac.cn; Yi, Xiaoyan, E-mail: lzq@semi.ac.cn, E-mail: spring@semi.ac.cn; Li, Jinmin [R& D Center for Semiconductor Lighting, Chinese Academy of Sciences, Beijing 100083,P. R. China (China); State Key Laboratory of Solid State Lighting, Beijing 100083 (China); Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application, Beijing 100083 (China)

    2016-03-15

    In this work, a novel carrier concentration adjusting insertion layer for InGaN/GaN multiple quantum wells light-emitting diodes was proposed to mitigate the efficiency droop and improve optical output properties at high current density. The band diagrams and carrier distributions were investigated numerically and experimentally. The results indicate that due to the newly formed electron barrier and the adjusted built-in field near the active region, the hole injection has been improved and a better radiative recombination can be achieved. Compared to the conventional LED, the light output power of our new structure with the carrier concentration adjusting layers is enhanced by 127% at 350 mA , while the efficiency only droops to be 88.2% of its peak efficiency.

  7. Photoluminescence emission from Alq3 organic layer in metal–Alq3–metal plasmonic structure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bohr-Ran; Liao, Chung-Chi [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Fan, Wan-Ting [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China); Wu, Jin-Han; Chen, Cheng-Chang; Lin, Yi-Ping; Li, Jung-Yu; Chen, Shih-Pu [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute (ITRI), 195, Sec. 4, Chung-Hsin Road, Chutung 310, Taiwan (China); Ke, Wen-Cheng [Department of Mechanical Engineering, Yuan Ze University, Tao-Yuan 320, Taiwan (China); Chen, Nai-Chuan, E-mail: ncchen001@mail.cgu.edu.tw [Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China)

    2014-06-01

    The emission properties of an organic layer embedded in a metal–organic–metal (MOM) structure were investigated. A partially radiative odd-SPW as well as a non-radiative even-SPW modes are supported by hybridization of the SPW modes on the opposite organic/metal interface in the structure. Because of the competition by this radiative SPW, the population of excitons that recombine to form non-radiative SPW should be reduced. This may account for why the photoluminescence intensity of the MOM sample is higher than that of an organic–metal sample even though the MOM sample has an additional metal layer that should intuitively act as a filter.

  8. Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere

    Directory of Open Access Journals (Sweden)

    V. Barabash

    2014-03-01

    Full Text Available Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively, and the channel forming H+(H2On proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2On and O2+(H2On hydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2On pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water

  9. High-resolution structure of the recombinant sweet-tasting protein thaumatin I

    International Nuclear Information System (INIS)

    Masuda, Tetsuya; Ohta, Keisuke; Mikami, Bunzo; Kitabatake, Naofumi

    2011-01-01

    The structure of a recombinant form of the sweet-tasting protein thaumatin I was determined at 1.1 Å resolution and refined to an R work of 9.1% and an R free of 11.7%. Comparisons with plant thaumatin revealed the electron density of recombinant thaumatin I to be significantly improved, especially around Asn46 and Ser63. Thaumatin, an intensely sweet-tasting plant protein, elicits a sweet taste at a concentration of 50 nM. The crystal structure of a recombinant form of thaumatin I produced in the yeast Pichia pastoris has been determined to a resolution of 1.1 Å. The model was refined with anisotropic B parameters and riding H atoms. A comparison of the diffraction data and refinement statistics for recombinant thaumatin I with those for plant thaumatin I revealed no significant differences in the diffraction data. The R values for recombinant thaumatin I and plant thaumatin I (F o > 4σ) were 9.11% and 9.91%, respectively, indicating the final model to be of good quality. Notably, the electron-density maps around Asn46 and Ser63, which differ between thaumatin variants, were significantly improved. Furthermore, a number of H atoms became visible in an OMIT map and could be assigned. The high-quality structure of recombinant thaumatin with H atoms should provide details about sweetness determinants in thaumatin and provide valuable insights into the mechanism of its interaction with taste receptors

  10. An inducible expression system for high-level expression of recombinant proteins in slow growing mycobacteria.

    Science.gov (United States)

    Leotta, Lisa; Spratt, Joanne M; Kong, Carlyn U; Triccas, James A

    2015-09-01

    A novel protein expression vector utilising the inducible hspX promoter of Mycobacterium tuberculosis was constructed and evaluated in this study. High-level induction of three mycobacterial antigens, comprising up to 9% of bacterial sonicate, was demonstrated in recombinant Mycobacterium bovis BCG when grown under low-oxygen tension, which serves to enhance hspX promoter activity. Recombinant proteins were efficiently purified from bacterial lysates in a soluble form by virtue of a C-terminal 6-histidine tag. Purification of the immunodominant M. tuberculosis Ag85B antigen using this system resulted in a recombinant protein that stimulated significant IFN-γ release from Ag85B-reactive T cells generated after vaccination of mice with an Ag85B-expressing vaccine. Further, the M. tuberculosis L-alanine dehydrogenase (Ald) protein purified from recombinant BCG displayed strong enzymatic activity in recombinant form. This study demonstrated that high levels of native-like recombinant mycobacterial proteins can be produced in mycobacterial hosts, and this may aid the analysis of mycobacterial protein function and the development of new treatments. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Study of ozone gas formed in the industrial radiation process with cobalt-60 and its impact on the environment

    International Nuclear Information System (INIS)

    Uzueli, Daniel Henrique

    2013-01-01

    The radiation processing is present in various products such as foods, medical disposable, electrical cables, gems, among others. This process aims to improve the properties, sterilize or sanitize irradiated products. In industrial irradiators facilities, electromagnetic radiation (gamma and X-rays) or electrons before they interact with the products in processing, there are a layer of air. To interact with this air layer, it causes radiolytic effects on the molecules present in the ambient atmosphere, and the main interaction are with the oxygen molecules that have their bonds broken, separating them into two highly reactive atoms that recombine with the other molecule of oxygen to form ozone gas. In this work it was studied the formation, decay and dispersion of ozone in industrial gamma irradiators facilities that use cobalt-60 as a source of radiation. The monitoring of ozone concentration was performed by optical absorption method in a commercial monitor. (author)

  12. Genetic recombination as a major cause of mutagenesis in the human globin gene clusters.

    Science.gov (United States)

    Borg, Joseph; Georgitsi, Marianthi; Aleporou-Marinou, Vassiliki; Kollia, Panagoula; Patrinos, George P

    2009-12-01

    Homologous recombination is a frequent phenomenon in multigene families and as such it occurs several times in both the alpha- and beta-like globin gene families. In numerous occasions, genetic recombination has been previously implicated as a major mechanism that drives mutagenesis in the human globin gene clusters, either in the form of unequal crossover or gene conversion. Unequal crossover results in the increase or decrease of the human globin gene copies, accompanied in the majority of cases with minor phenotypic consequences, while gene conversion contributes either to maintaining sequence homogeneity or generating sequence diversity. The role of genetic recombination, particularly gene conversion in the evolution of the human globin gene families has been discussed elsewhere. Here, we summarize our current knowledge and review existing experimental evidence outlining the role of genetic recombination in the mutagenic process in the human globin gene families.

  13. Generation of monoclonal antibodies for the assessment of protein purification by recombinant ribosomal coupling

    DEFF Research Database (Denmark)

    Kristensen, Janni; Sperling-Petersen, Hans Uffe; Mortensen, Kim Kusk

    2005-01-01

    We recently described a conceptually novel method for the purification of recombinant proteins with a propensity to form inclusion bodies in the cytoplasm of Escherichia coli. Recombinant proteins were covalently coupled to the E. coli ribosome by fusing them to ribosomal protein 23 (rpL23...... therefore purified rpL23-GFP-His, rpL23-His and GFP from E. coli recombinants using affinity, ion exchange and hydrophobic interaction chromatography. These proteins could be purified with yields of 150, 150 and 1500 microg per gram cellular wet weight, respectively. However, rpL23-GFP-His could only...... proteolytic cleavage sites. We conclude that the generated antibodies can be used to evaluate ribosomal coupling of recombinant target proteins as well as the efficiency of their separation from the ribosome....

  14. Electron-ion recombination rates for merged-beams experiments

    International Nuclear Information System (INIS)

    Pajek, M.

    1994-01-01

    Energy dependence of the electron-ion recombination rates are studied for different recombination processes (radiative recombination, three-body recombination, dissociative recombination) for Maxwellian relative velocity distribution of arbitrary asymmetry. The results are discussed in context of the electron-ion merged beams experiments in cooling ion storage rings. The question of indication of a possible contribution of the three-body recombination to the measured recombination rates versus relative energy is particularly addressed. Its influence on the electron beam temperature derived from the energy dependence of recombination rate is discussed

  15. First-principles study of Frenkel pair recombination in tungsten

    International Nuclear Information System (INIS)

    Qin, Shi-Yao; Jin, Shuo; Li, Yu-Hao; Zhou, Hong-Bo; Zhang, Ying; Lu, Guang-Hong

    2017-01-01

    The recombination of one Frenkel pair in tungsten has been investigated through first-principles simulation. Two different recombination types have been identified: instantaneous and thermally activated. The small recombination barriers for thermally activated recombination cases indicate that recombination can occur easily with a slightly increased temperature. For both of the two recombination types, recombination occurs through the self-interstitial atom moving towards the vacancy. The recombination process can be direct or through replacement sequences, depending on the vertical distance between the vacancy and the 〈1 1 1〉 line of self-interstitial atom pair.

  16. Induction of homologous recombination in Saccharomyces cerevisiae.

    Science.gov (United States)

    Simon, J R; Moore, P D

    1988-09-01

    We have investigated the effects of UV irradiation of Saccharomyces cerevisiae in order to distinguish whether UV-induced recombination results from the induction of enzymes required for homologous recombination, or the production of substrate sites for recombination containing regions of DNA damage. We utilized split-dose experiments to investigate the induction of proteins required for survival, gene conversion, and mutation in a diploid strain of S. cerevisiae. We demonstrate that inducing doses of UV irradiation followed by a 6 h period of incubation render the cells resistant to challenge doses of UV irradiation. The effects of inducing and challenge doses of UV irradiation upon interchromosomal gene conversion and mutation are strictly additive. Using the yeast URA3 gene cloned in non-replicating single- and double-stranded plasmid vectors that integrate into chromosomal genes upon transformation, we show that UV irradiation of haploid yeast cells and homologous plasmid DNA sequences each stimulate homologous recombination approximately two-fold, and that these effects are additive. Non-specific DNA damage has little effect on the stimulation of homologous recombination, as shown by studies in which UV-irradiated heterologous DNA was included in transformation/recombination experiments. We further demonstrate that the effect of competing single- and double-stranded heterologous DNA sequences differs in UV-irradiated and unirradiated cells, suggesting an induction of recombinational machinery in UV-irradiated S. cerevisiae cells.

  17. Optimal Silicon Doping Layers of Quantum Barriers in the Growth Sequence Forming Soft Confinement Potential of Eight-Period In0.2Ga0.8N/GaN Quantum Wells of Blue LEDs

    Science.gov (United States)

    Wang, Hsiang-Chen; Chen, Meng-Chu; Lin, Yen-Sheng; Lu, Ming-Yen; Lin, Kuang-I.; Cheng, Yung-Chen

    2017-11-01

    The features of eight-period In0.2Ga0.8N/GaN quantum wells (QWs) with silicon (Si) doping in the first two to five quantum barriers (QBs) in the growth sequence of blue light-emitting diodes (LEDs) are explored. Epilayers of QWs' structures are grown on 20 pairs of In0.02Ga0.98N/GaN superlattice acting as strain relief layers (SRLs) on patterned sapphire substrates (PSSs) by a low-pressure metal-organic chemical vapor deposition (LP-MOCVD) system. Temperature-dependent photoluminescence (PL) spectra, current versus voltage ( I- V) curves, light output power versus injection current ( L- I) curves, and images of high-resolution transmission electron microscopy (HRTEM) of epilayers are measured. The consequences show that QWs with four Si-doped QBs have larger carrier localization energy (41 meV), lower turn-on (3.27 V) and breakdown (- 6.77 V) voltages, and higher output power of light of blue LEDs at higher injection current than other samples. Low barrier height of QBs in a four-Si-doped QB sample results in soft confinement potential of QWs and lower turn-on and breakdown voltages of the diode. HRTEM images give the evidence that this sample has relatively diffusive interfaces of QWs. Uniform spread of carriers among eight QWs and superior localization of carriers in each well are responsible for the enhancement of light output power, in particular, for high injection current in the four-Si-doped QB sample. The results demonstrate that four QBs of eight In0.2Ga0.8N/GaN QWs with Si doping not only reduce the quantum-confined Stark effect (QCSE) but also improve the distribution and localization of carriers in QWs for better optical performance of blue LEDs.

  18. Influence of selenium amount on the structural and electronic properties of Cu(In,Ga)Se{sub 2} thin films and solar cells formed by the stacked elemental layer process

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, B.J., E-mail: bjm.mueller@web.de [Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany); Corporate Research, Robert Bosch GmbH, D-71272 Renningen (Germany); Opasanont, B.; Haug, V. [Corporate Research, Robert Bosch GmbH, D-71272 Renningen (Germany); Hergert, F. [Bosch Solar CISTech GmbH, D-14772 Brandenburg (Germany); Zweigart, S. [Corporate Research, Robert Bosch GmbH, D-71272 Renningen (Germany); Herr, U., E-mail: ulrich.herr@uni-ulm.de [Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany)

    2016-06-01

    In the following article the influence of selenium supply on the stacked elemental layer process during the final annealing step is investigated. We find that the Se supply strongly influences the phase formation in the Cu(In,Ga)Se {sub 2} resulting in a modified Ga/In distribution. The effects of Se supply on the structural and electronic properties of the films are reported. The solar cell performance has been investigated in detail using current voltage and external quantum efficiency measurements. We find that the chalcopyrite crystal formation is strongly influenced by the Se supply during the growth process. Furthermore the interdiffusion of Ga and In is accelerated with increasing Se amount. This has direct consequences on band gap and series resistance, which leads to changes in the values of short-circuit current density, open-circuit voltage and fill factor. The open-circuit voltage increases with increasing band gap of the Cu(In,Ga)Se {sub 2}, whereas the short-circuit current density decreases with increasing band gap. The fill factor is affected by the formation of MoSe {sub 2} at the back contact. The experimental findings are compared with the theoretical efficiency limits calculated from the Shockley–Queisser model, and also with numerical 1D SCAPS simulations. - Highlights: • Adjustment of the Ga/In distribution by the Se supply • Enhanced Ga incorporation near-surface • Interdiffusion coefficients of Ga/In are investigated. • Shockley–Queisser modeling and 1D SCAPS simulations • Fill factor is strongly coupled on the MoSe2/Mo ratio.

  19. Growth and characterization of highly tensile strained Ge{sub