Accumulation capacitance frequency dispersion of III-V metal-insulator-semiconductor devices due to disorder induced gap states

International Nuclear Information System (INIS)

Galatage, R. V.; Zhernokletov, D. M.; Dong, H.; Brennan, B.; Hinkle, C. L.; Wallace, R. M.; Vogel, E. M.

2014-01-01

The origin of the anomalous frequency dispersion in accumulation capacitance of metal-insulator-semiconductor devices on InGaAs and InP substrates is investigated using modeling, electrical characterization, and chemical characterization. A comparison of the border trap model and the disorder induced gap state model for frequency dispersion is performed. The fitting of both models to experimental data indicate that the defects responsible for the measured dispersion are within approximately 0.8 nm of the surface of the crystalline semiconductor. The correlation between the spectroscopically detected bonding states at the dielectric/III-V interface, the interfacial defect density determined using capacitance-voltage, and modeled capacitance-voltage response strongly suggests that these defects are associated with the disruption of the III-V atomic bonding and not border traps associated with bonding defects within the high-k dielectric.

Ultrabroadband Hybrid III-V/SOI Grating Reflector for On-chip Lasers

DEFF Research Database (Denmark)

Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

2016-01-01

We report on a new type of III-V/SOI grating reflector with a broad stopband of 350 nm. This reflector has promising prospects for applications in high-speed III-V/SOI vertical cavity lasers with an improved heat dissipation capability.......We report on a new type of III-V/SOI grating reflector with a broad stopband of 350 nm. This reflector has promising prospects for applications in high-speed III-V/SOI vertical cavity lasers with an improved heat dissipation capability....

High Efficiency Quantum Dot III-V Multijunction Solar Cell for Space Power, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — We are proposing to utilize quantum dots to develop a super high-efficiency multijunction III-V solar cell for space. In metamorphic triple junction space solar...

Th(As(III)4As(V)4O18): a mixed-valent oxoarsenic(III)/arsenic(V) actinide compound obtained under extreme conditions.

Science.gov (United States)

Yu, Na; Klepov, Vladislav V; Kegler, Philip; Bosbach, Dirk; Albrecht-Schmitt, Thomas E; Alekseev, Evgeny V

2014-08-18

A high-temperature/high-pressure method was employed to investigate phase formation in the Th(NO3)4·5H2O-As2O3-CsNO3 system. It was observed that an excess of arsenic(III) in starting system leads to the formation of Th(As(III)4As(V)4O18), which is representative of a rare class of mixed-valent arsenic(III)/arsenic(V) compounds. This compound was studied with X-ray diffraction, energy-dispersive X-ray, and Raman spectroscopy methods. Crystallographic data show that Th(As(III)4As(V)4O18) is built from (As(III)4As(V)4O18)(4-) layers connected through Th atoms. The arsenic layers are found to be isoreticular to those in previously reported As2O3 and As3O5(OH), and the geometric differences between them are discussed. Bands in the Raman spectrum are assigned with respect to the presence of AsO3 and AsO4 groups.

Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides

International Nuclear Information System (INIS)

Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G.S.E.

2014-01-01

Highlights: • Fe(III)–Cr(III) hydroxides enhance groundwater quality better than pure Cr(III) compounds. • Crystalline Cr(OH) 3 ·3H 2 O was unstable, with a solubility higher than 50 μg/l. • Amorphous Cr(OH) 3 (am) was stable with a solubility lower than 50 μg/l in the range 5.7 0.75 Cr 0.25 (OH) 3 , the stability region was extended to 4.8 3 ·xH 2 O whereas in the presence of iron the precipitate is a mixed Fe (1−x) Cr x (OH) 3 phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fe x ,Cr 1−x )(OH) 3 hydroxides as compared to the stability of Cr(OH) 3 . We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH) 3 ·3H 2 O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH) 3 (am) phase. Mixed Fe 0.75 Cr 0.25 (OH) 3 hydroxides were found to be of the ferrihydrite structure, Fe(OH) 3 , and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)–Cr(III) hydroxides are more effective enhancers of groundwater quality, in comparison to the plain amorphous or crystalline Cr(III) hydroxides, the latter found to have a solubility typically higher than 50 μg/l (maximum EU permitted Cr level in drinking water), while the amorphous Cr(OH) 3 (am) phase was within the drinking water threshold in the range 5.7 0.75 Cr 0.25 (OH) 3 hydroxides studied were of extended stability in the 4.8 < pH < 13.5 range

III-V microelectronics

CERN Document Server

Nougier, JP

1991-01-01

As is well known, Silicon widely dominates the market of semiconductor devices and circuits, and in particular is well suited for Ultra Large Scale Integration processes. However, a number of III-V compound semiconductor devices and circuits have recently been built, and the contributions in this volume are devoted to those types of materials, which offer a number of interesting properties. Taking into account the great variety of problems encountered and of their mutual correlations when fabricating a circuit or even a device, most of the aspects of III-V microelectronics, from fundamental p

Magnetooptical investigations on ferromagnetic III-V-semiconductors; Magnetooptische Untersuchungen an ferromagnetischen III-V-Halbleitern

Energy Technology Data Exchange (ETDEWEB)

Winter, Andreas

2009-07-23

Magnetooptical Kerr effect (MOKE) and Magnetic Circular Dichroism (MCD) have been used to investigate magnetic as well as bandstructure properties of diluted magnetic III-V-semiconductors containing Mn. In these ferromagnetic systems it has been found that the strength of the observed effects depends linearly on the magnetization of the samples with no influence of the external magnetic field. The magnetooptical effects allowed the recording of hysteresis loops of GaMnAs, GaMnSb, InMnAs and InMnSb samples for different temperatures and in the case of GaMnAs also for different alignments of the external magnetic field with respect to the easy axis of magnetization. The Stoner-Wohlfahrt-Model has been used to describe the resulting shapes of the loops yielding the magnetic anisotropy parameters of the samples. For magnetically saturated samples, spectra of MOKE and MCD have been recorded. Contrary to pure III-V-semiconductors, which exhibit lots of sharp resonances due to interband transitions between Landau levels, III-Mn-V-semi-conductors how only very few (or just one) considerably broad resonance(s). Their spectral position(s) do(es) neither depend upon the magnetic field as it would be the case for pure III-V-semiconductors nor the magnetization. Only the amplitude increases linearly with the magnetization. Utilizing a kp-theory it has been possible to describe the observed dependencies. Valence- and conduction-band are split into Landau levels by the external magnetic field and, in addition to the Zeeman-effect, the spin-levels are split by the exchange interaction between the localized electrons of the Mn ions and the free carriers which is proportional to the magnetization of the samples. This splitting is much bigger than the Landau level splitting. Due to an inhomogeneous distribution of the Mn ions and due to the high carrier density the Landau levels are strongly broadened and their structure is not observable. Owing to the high carrier-concentration in

Transformational III-V Electronics

KAUST Repository

Nour, Maha A.

2014-04-01

Flexible electronics using III-V materials for nano-electronics with high electron mobility and optoelectronics with direct band gap are attractive for many applications. This thesis describes a complementary metal oxide semiconductor (CMOS) compatible process for transforming traditional III-V materials based electronics into flexible one. The thesis reports releasing 200 nm of Gallium Arsenide (GaAs) from 200 nm GaAs / 300 nm Aluminum Arsenide (AlAs) stack on GaAs substrate using diluted hydrofluoric acid (HF). This process enables releasing a single top layer compared to peeling off all layers with small sizes at the same time. This is done utilizing a network of release holes that contributes to the better transparency (45 % at 724 nm wavelengths) observed. Fabrication of metal oxide semiconductor capacitor (MOSCAPs) on GaAs is followed by releasing it to have devices on flexible 200 nm GaAs. Similarly, flexible GaSb and InP fabrication process is also reported to transform traditional electronics into large-area flexible electronics.

New III-V cell design approaches for very high efficiency. Annual subcontract report, 1 August 1990--31 July 1991

Energy Technology Data Exchange (ETDEWEB)

Lundstrom, M.S.; Melloch, M.R.; Lush, G.B.; O`Bradovich, G.J.; Young, M.P. [Purdue Univ., Lafayette, IN (United States)

1993-01-01

This report describes progress during the first year of a three-year project. The objective of the research is to examine new design approaches for achieving very high conversion efficiencies. The program is divided into two areas. The first centers on exploring new thin-film approaches specifically designed for III-V semiconductors. The second area centers on exploring design approaches for achieving high conversion efficiencies without requiring extremely high quality material. Research activities consisted of an experimental study of minority carrier recombination in n-type, metal-organic chemical vapor deposition (MOCVD)-deposited GaAs, an assessment of the minority carrier lifetimes in n-GaAs grown by molecular beam epitaxy, and developing a high-efficiency cell fabrication process.

Concomitant glenohumeral pathologies in high-grade acromioclavicular separation (type III - V).

Science.gov (United States)

Markel, Jochen; Schwarting, Tim; Malcherczyk, Dominik; Peterlein, Christian-Dominik; Ruchholtz, Steffen; El-Zayat, Bilal Farouk

2017-11-10

Acromioclavicular joint (ACJ) dislocations are common injuries of the shoulder associated with physical activity. The diagnosis of concomitant injuries proves complicated due to the prominent clinical symptoms of acute ACJ dislocation. Because of increasing use of minimally invasive surgery techniques concomitant pathologies are diagnosed more often than with previous procedures. The aim of this study was to identify the incidence of concomitant intraarticular injuries in patients with high-grade acromioclavicular separation (Rockwood type III - V) as well as to reveal potential risk constellations. The concomitant pathologies were compiled during routine arthroscopically assisted treatment in altogether 163 patients (147 male; 16 female; mean age 36.8 years) with high-grade acromioclavicular separation (Rockwood type III: n = 60; Rockwood type IV: n = 6; Rockwood type V: n = 97). Acromioclavicular separation occurred less often in women than men (1:9). In patients under 35, the most common cause for ACJ dislocation was sporting activity (37.4%). Rockwood type V was observed significantly more often than the other types with 57.5% (Rockwood type III = 36.8%, Rockwood type IV 3.7%). Concomitant pathologies were diagnosed in 39.3% of the patients with that number rising to as much as 57.3% in patients above 35 years. Most common associated injuries were rotator cuff injuries (32.3%), chondral defects (30.6%) and SLAP-lesions (22.6%). Of all patients, 8.6% needed additional reconstructive surgery. Glenohumeral injuries are a much more common epiphenomenon during acromioclavicular separation than previously ascertained. High risk group for accompanying injuries are patients above 35 years with preexisting degenerative disease. The increasing use of minimally invasive techniques allows for an easier diagnosis and simultaneous treatment of the additional pathologies.

Molecular Beam Epitaxy Growth of High Crystalline Quality LiNbO3

Science.gov (United States)

Tellekamp, M. Brooks; Shank, Joshua C.; Goorsky, Mark S.; Doolittle, W. Alan

2016-12-01

Lithium niobate is a multi-functional material with wide reaching applications in acoustics, optics, and electronics. Commercial applications for lithium niobate require high crystalline quality currently limited to bulk and ion sliced material. Thin film lithium niobate is an attractive option for a variety of integrated devices, but the research effort has been stagnant due to poor material quality. Both lattice matched and mismatched lithium niobate are grown by molecular beam epitaxy and studied to understand the role of substrate and temperature on nucleation conditions and material quality. Growth on sapphire produces partially coalesced columnar grains with atomically flat plateaus and no twin planes. A symmetric rocking curve shows a narrow linewidth with a full width at half-maximum (FWHM) of 8.6 arcsec (0.0024°), which is comparable to the 5.8 arcsec rocking curve FWHM of the substrate, while the film asymmetric rocking curve is 510 arcsec FWHM. These values indicate that the individual grains are relatively free of long-range disorder detectable by x-ray diffraction with minimal measurable tilt and twist and represents the highest structural quality epitaxial material grown on lattice mismatched sapphire without twin planes. Lithium niobate is also grown on lithium tantalate producing high quality coalesced material without twin planes and with a symmetric rocking curve of 193 arcsec, which is nearly equal to the substrate rocking curve of 194 arcsec. The surface morphology of lithium niobate on lithium tantalate is shown to be atomically flat by atomic force microscopy.

Hybrid III-V/silicon lasers

Science.gov (United States)

Kaspar, P.; Jany, C.; Le Liepvre, A.; Accard, A.; Lamponi, M.; Make, D.; Levaufre, G.; Girard, N.; Lelarge, F.; Shen, A.; Charbonnier, P.; Mallecot, F.; Duan, G.-H.; Gentner, J.-.; Fedeli, J.-M.; Olivier, S.; Descos, A.; Ben Bakir, B.; Messaoudene, S.; Bordel, D.; Malhouitre, S.; Kopp, C.; Menezo, S.

2014-05-01

The lack of potent integrated light emitters is one of the bottlenecks that have so far hindered the silicon photonics platform from revolutionizing the communication market. Photonic circuits with integrated light sources have the potential to address a wide range of applications from short-distance data communication to long-haul optical transmission. Notably, the integration of lasers would allow saving large assembly costs and reduce the footprint of optoelectronic products by combining photonic and microelectronic functionalities on a single chip. Since silicon and germanium-based sources are still in their infancy, hybrid approaches using III-V semiconductor materials are currently pursued by several research laboratories in academia as well as in industry. In this paper we review recent developments of hybrid III-V/silicon lasers and discuss the advantages and drawbacks of several integration schemes. The integration approach followed in our laboratory makes use of wafer-bonded III-V material on structured silicon-on-insulator substrates and is based on adiabatic mode transfers between silicon and III-V waveguides. We will highlight some of the most interesting results from devices such as wavelength-tunable lasers and AWG lasers. The good performance demonstrates that an efficient mode transfer can be achieved between III-V and silicon waveguides and encourages further research efforts in this direction.

Growth, structure and phase transitions of epitaxial nanowires of III-V semiconductors

International Nuclear Information System (INIS)

Glas, F; Patriarche, G; Harmand, J C

2010-01-01

We review and illustrate the impact of TEM on the study of nanowires of non-nitride III-V semiconductors, with particular emphasis on the understanding of the thermodynamics and kinetics of their formation assisted by nano-sized catalyst particles. Besides providing basic information about the morphology of the nanowires and their growth rate as a function of diameter, TEM offers insights into the peculiar crystalline structure that they adopt. We discuss the formation of the unusual wurtzite hexagonal crystalline phase and that of planar stacking defects in these nanowires and show that they are kinetically controlled. We also demonstrate the transformation of wurtzite into cubic sphalerite upon epitaxial burying of the nanowires. Nanowires are particularly interesting in that they allow the fabrication of precisely positioned quantum dots with well-defined geometries. In this respect, we discuss the formation of strained quantum-size inclusions in nanowires, their critical dimensions and the kinetic and thermodynamic factors governing the changes of the crystalline structure that sometimes occur around a hetero-interface.

David Adler Lectureship Award Talk: III-V Semiconductor Nanowires on Silicon for Future Devices

Science.gov (United States)

Riel, Heike

Bottom-up grown nanowires are very attractive materials for direct integration of III-V semiconductors on silicon thus opening up new possibilities for the design and fabrication of nanoscale devices for electronic, optoelectronic as well as quantum information applications. Template-Assisted Selective Epitaxy (TASE) allows the well-defined and monolithic integration of complex III-V nanostructures and devices on silicon. Achieving atomically abrupt heterointerfaces, high crystal quality and control of dimension down to 1D nanowires enabled the demonstration of FETs and tunnel devices based on In(Ga)As and GaSb. Furthermore, the strong influence of strain on nanowires as well as results on quantum transport studies of InAs nanowires with well-defined geometry will be presented.

Surface passivation technology for III-V semiconductor nanoelectronics

International Nuclear Information System (INIS)

Hasegawa, Hideki; Akazawa, Masamichi

2008-01-01

The present status and key issues of surface passivation technology for III-V surfaces are discussed in view of applications to emerging novel III-V nanoelectronics. First, necessities of passivation and currently available surface passivation technologies for GaAs, InGaAs and AlGaAs are reviewed. Then, the principle of the Si interface control layer (ICL)-based passivation scheme by the authors' group is introduced and its basic characterization is presented. Ths Si ICL is a molecular beam epitaxy (MBE)-grown ultrathin Si layer inserted between III-V semiconductor and passivation dielectric. Finally, applications of the Si ICL method to passivation of GaAs nanowires and GaAs nanowire transistors and to realization of pinning-free high-k dielectric/GaAs MOS gate stacks are presented

III-V semiconductor materials and devices

CERN Document Server

Malik, R J

1989-01-01

The main emphasis of this volume is on III-V semiconductor epitaxial and bulk crystal growth techniques. Chapters are also included on material characterization and ion implantation. In order to put these growth techniques into perspective a thorough review of the physics and technology of III-V devices is presented. This is the first book of its kind to discuss the theory of the various crystal growth techniques in relation to their advantages and limitations for use in III-V semiconductor devices.

Research progress of III-V laser bonding to Si

Science.gov (United States)

Bo, Ren; Yan, Hou; Yanan, Liang

2016-12-01

The vigorous development of silicon photonics makes a silicon-based light source essential for optoelectronics' integration. Bonding of III-V/Si hybrid laser has developed rapidly in the last ten years. In the tireless efforts of researchers, we are privileged to see these bonding methods, such as direct bonding, medium adhesive bonding and low temperature eutectic bonding. They have been developed and applied to the research and fabrication of III-V/Si hybrid lasers. Some research groups have made remarkable progress. Tanabe Katsuaki of Tokyo University successfully implemented a silicon-based InAs/GaAs quantum dot laser with direct bonding method in 2012. They have bonded the InAs/GaAs quantum dot laser to the silicon substrate and the silicon ridge waveguide, respectively. The threshold current of the device is as low as 200 A/cm2. Stevan Stanković and Sui Shaoshuai successfully produced a variety of hybrid III-V/Si laser with the method of BCB bonding, respectively. BCB has high light transmittance and it can provide high bonding strength. Researchers of Tokyo University and Peking University have realized III-V/Si hybrid lasers with metal bonding method. We describe the progress in the fabrication of III-V/Si hybrid lasers with bonding methods by various research groups in recent years. The advantages and disadvantages of these methods are presented. We also introduce the progress of the growth of III-V epitaxial layer on silicon substrate, which is also a promising method to realize silicon-based light source. I hope that readers can have a general understanding of this field from this article and we can attract more researchers to focus on the study in this field.

Development of III-V/Si Multijunction Space Photovoltaics

Data.gov (United States)

National Aeronautics and Space Administration — High substrate costs, as well as weight, typically play a major role in the high costs of multijunction space solar cell production and deployment. III-V/Si...

Flow injection spectrophotometric determination of Fe(III) and V(v)

International Nuclear Information System (INIS)

Elrahman, Azza Mohamed

2000-01-01

Phenylflourone was synthesized with the objective of developing a method for determining Fe(III) and V(V) in the pressence of micelles using flow injectoin technique. Phenylflourone showed a wavelength of maximum absorption at 412 nm which was not affected by the presence of miccelles i.e. n-hexadodecylpyridinum bromide and sodium n-dodecylsulphate, but they have different effects on the absorbance of PHF. The example of PHF-Fe(III) and PHF-V(V) showed the wavelength of the maximum absorption at 4428 nm and 412 nm, respectively. Presence of micelles shifted the wavelength of the two complexes to a lower one. Generally the addition of micelles increased the absorbance of phenylflourone metal ions complexes except for PHF-V(V) with hexadodecylpyridinum bromide. With flow injection technique two approaches were practiced the use of micelle as a carrier or water as a carrier. Sodium n-dodecylsulphate increased the absorbance of the two complexes when it was used as a carrier or added to the metal ions using water as carrier. On the other hand, the use of n-hexadodecylpyridinum bromide as carrieer increased the absorbance of the complexes but it decreased the absorbance when it was used in conjunction with metal ions and water as a carrier. After establishing the optimum FI conditions for PHF-Fe(III) and PHF-V(V) complexes, the calibration curves were construction and produced semiliner response in the concentration range studied. Ti(IV) III, Mo(VI) showed a positive interference in PHF-Fe(III) and PHF-V(V) complexes, respectively.(Author)

Antisites in III-V semiconductors: Density functional theory calculations

KAUST Repository

Chroneos, A.

2014-07-14

Density functional based simulation, corrected for finite size effects, is used to investigate systematically the formation of antisite defects in III-V semiconductors (III=Al, Ga, and In and V=P, As, and Sb). Different charge states are modelled as a function of the Fermi level and under different growth conditions. The formation energies of group III antisites (III V q) decrease with increasing covalent radius of the group V atom though not group III radius, whereas group V antisites (V I I I q) show a consistent decrease in formation energies with increase in group III and group V covalent radii. In general, III V q defects dominate under III-rich conditions and V I I I q under V-rich conditions. Comparison with equivalent vacancy formation energy simulations shows that while antisite concentrations are always dominant under stoichiometric conditions, modest variation in growth or doping conditions can lead to a significantly higher concentration of vacancies. © 2014 AIP Publishing LLC.

Low Thermal Budget Fabrication of III-V Quantum Nanostructures on Si Substrates

International Nuclear Information System (INIS)

Bietti, S; Somaschini, C; Sanguinetti, S; Koguchi, N; Isella, G; Chrastina, D; Fedorov, A

2010-01-01

We show the possibility to integrate high quality III-V quantum nanostructures tunable in shape and emission energy on Si-Ge Virtual Substrate. Strong photoemission is observed, also at room temperature, from two different kind of GaAs quantum nanostructures fabricated on Silicon substrate. Due to the low thermal budget of the procedure used for the fabrication of the active layer, Droplet Epitaxy is to be considered an excellent candidate for implementation of optoelectronic devices on CMOS circuits.

A III-V nanowire channel on silicon for high-performance vertical transistors.

Science.gov (United States)

Tomioka, Katsuhiro; Yoshimura, Masatoshi; Fukui, Takashi

2012-08-09

Silicon transistors are expected to have new gate architectures, channel materials and switching mechanisms in ten years' time. The trend in transistor scaling has already led to a change in gate structure from two dimensions to three, used in fin field-effect transistors, to avoid problems inherent in miniaturization such as high off-state leakage current and the short-channel effect. At present, planar and fin architectures using III-V materials, specifically InGaAs, are being explored as alternative fast channels on silicon because of their high electron mobility and high-quality interface with gate dielectrics. The idea of surrounding-gate transistors, in which the gate is wrapped around a nanowire channel to provide the best possible electrostatic gate control, using InGaAs channels on silicon, however, has been less well investigated because of difficulties in integrating free-standing InGaAs nanostructures on silicon. Here we report the position-controlled growth of vertical InGaAs nanowires on silicon without any buffering technique and demonstrate surrounding-gate transistors using InGaAs nanowires and InGaAs/InP/InAlAs/InGaAs core-multishell nanowires as channels. Surrounding-gate transistors using core-multishell nanowire channels with a six-sided, high-electron-mobility transistor structure greatly enhance the on-state current and transconductance while keeping good gate controllability. These devices provide a route to making vertically oriented transistors for the next generation of field-effect transistors and may be useful as building blocks for wireless networks on silicon platforms.

High-Throughput Multiple Dies-to-Wafer Bonding Technology and III/V-on-Si Hybrid Lasers for Heterogeneous Integration of Optoelectronic Integrated Circuits

Directory of Open Access Journals (Sweden)

Xianshu eLuo

2015-04-01

Full Text Available Integrated optical light source on silicon is one of the key building blocks for optical interconnect technology. Great research efforts have been devoting worldwide to explore various approaches to integrate optical light source onto the silicon substrate. The achievements so far include the successful demonstration of III/V-on-Si hybrid lasers through III/V-gain material to silicon wafer bonding technology. However, for potential large-scale integration, leveraging on mature silicon complementary metal oxide semiconductor (CMOS fabrication technology and infrastructure, more effective bonding scheme with high bonding yield is in great demand considering manufacturing needs. In this paper, we propose and demonstrate a high-throughput multiple dies-to-wafer (D2W bonding technology which is then applied for the demonstration of hybrid silicon lasers. By temporarily bonding III/V dies to a handle silicon wafer for simultaneous batch processing, it is expected to bond unlimited III/V dies to silicon device wafer with high yield. As proof-of-concept, more than 100 III/V dies bonding to 200 mm silicon wafer is demonstrated. The high performance of the bonding interface is examined with various characterization techniques. Repeatable demonstrations of 16-III/V-die bonding to pre-patterned 200 mm silicon wafers have been performed for various hybrid silicon lasers, in which device library including Fabry-Perot (FP laser, lateral-coupled distributed feedback (LC-DFB laser with side wall grating, and mode-locked laser (MLL. From these results, the presented multiple D2W bonding technology can be a key enabler towards the large-scale heterogeneous integration of optoelectronic integrated circuits (H-OEIC.

Low-temperature growth of highly crystalline β-Ga2O3 nanowires by solid-source chemical vapor deposition.

Science.gov (United States)

Han, Ning; Wang, Fengyun; Yang, Zaixing; Yip, SenPo; Dong, Guofa; Lin, Hao; Fang, Ming; Hung, TakFu; Ho, Johnny C

2014-01-01

Growing Ga2O3 dielectric materials at a moderately low temperature is important for the further development of high-mobility III-V semiconductor-based nanoelectronics. Here, β-Ga2O3 nanowires are successfully synthesized at a relatively low temperature of 610°C by solid-source chemical vapor deposition employing GaAs powders as the source material, which is in a distinct contrast to the typical synthesis temperature of above 1,000°C as reported by other methods. In this work, the prepared β-Ga2O3 nanowires are mainly composed of Ga and O elements with an atomic ratio of approximately 2:3. Importantly, they are highly crystalline in the monoclinic structure with varied growth orientations in low-index planes. The bandgap of the β-Ga2O3 nanowires is determined to be 251 nm (approximately 4.94 eV), in good accordance with the literature. Also, electrical characterization reveals that the individual nanowire has a resistivity of up to 8.5 × 10(7) Ω cm, when fabricated in the configuration of parallel arrays, further indicating the promise of growing these highly insulating Ga2O3 materials in this III-V nanowire-compatible growth condition. 77.55.D; 61.46.Km; 78.40.Fy.

High-quality single crystalline NiO with twin phases grown on sapphire substrate by metalorganic vapor phase epitaxy

Directory of Open Access Journals (Sweden)

Kazuo Uchida

2012-12-01

Full Text Available High-quality single crystalline twin phase NiO grown on sapphire substrates by metalorganic vapor phase epitaxy is reported. X-ray rocking curve analysis of NiO films grown at different temperatures indicates a minimum full width at half maximum of the cubic (111 diffraction peak of 0.107° for NiO film grown at as low as 550 °C. Detailed microstructural analysis by Φ scan X-ray diffraction and transmission electron microscopy reveal that the NiO film consists of large single crystalline domains with two different crystallographic orientations which are rotated relative to each other along the [111] axis by 60°. These single crystal domains are divided by the twin phase boundaries.

Electrospun single crystalline fork-like K2V8O21 as high-performance cathode materials for lithium-ion batteries

Science.gov (United States)

Hao, Pengfei; Zhu, Ting; Su, Qiong; Lin, Jiande; Cui, Rong; Cao, Xinxin; Wang, Yaping; Pan, Anqiang

2018-06-01

Single crystalline fork-like potassium vanadate (K2V8O21) has been successfully prepared through electrospinning combined with a subsequent annealing process. The as-obtained K2V8O21 forks show a unique layer-by-layer stacked structure with conductive carbon. When used as cathode materials for lithium-ion batteries, the as-prepared fork-like materials exhibit high specific discharge capacity and excellent cyclic stability. High specific discharge capacity of 200.2 mA h g-1 and 131.5 mA h g-1 can be delivered at the current densities of 50 mA g-1 and 500 mA g-1, respectively. Furthermore, the K2V8O21 electrodes exhibit excellent long-term cycling stability that maintain a capacity of 108.3 mA h g-1 after 300 cycles at 500 mA g-1 with a fading rate of only 0.054% per cycle, revealing their potential applications in next generation high-performance lithium-ion batteries.

Antisites in III-V semiconductors: Density functional theory calculations

KAUST Repository

Chroneos, A.; Tahini, Hassan Ali; Schwingenschlö gl, Udo; Grimes, R. W.

2014-01-01

as a function of the Fermi level and under different growth conditions. The formation energies of group III antisites (III V q) decrease with increasing covalent radius of the group V atom though not group III radius, whereas group V antisites (V I I I

Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides

Energy Technology Data Exchange (ETDEWEB)

Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G.S.E., E-mail: gantipas@metal.ntua.gr

2014-01-15

Highlights: • Fe(III)–Cr(III) hydroxides enhance groundwater quality better than pure Cr(III) compounds. • Crystalline Cr(OH){sub 3}·3H{sub 2}O was unstable, with a solubility higher than 50 μg/l. • Amorphous Cr(OH){sub 3}(am) was stable with a solubility lower than 50 μg/l in the range 5.7 < pH < 11. • For mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3}, the stability region was extended to 4.8 < pH < 13.5. -- Abstract: Chromium is a common contaminant of soils and aquifers and constitutes a major environmental problem. In nature, chromium usually exists in the form of two oxidation states, trivalent, Cr(III), which is relatively innocuous for biota and for the aquatic environment, and hexavalent, Cr(VI) which is toxic, carcinogenic and very soluble. Accordingly, the majority of wastewater and groundwater treatment technologies, include a stage where Cr(VI) is reduced to Cr(III), in order to remove chromium from the aqueous phase and bind the element in the form of environmentally stable solid compounds. In the absence of iron the final product is typically of the form Cr(OH){sub 3}·xH{sub 2}O whereas in the presence of iron the precipitate is a mixed Fe{sub (1−x)}Cr{sub x}(OH){sub 3} phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fe{sub x},Cr{sub 1−x})(OH){sub 3} hydroxides as compared to the stability of Cr(OH){sub 3}. We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH){sub 3}·3H{sub 2}O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH){sub 3}(am) phase. Mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3} hydroxides were found to be of the ferrihydrite structure, Fe(OH){sub 3}, and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)–Cr(III

III-V-on-silicon solar cells reaching 33% photoconversion efficiency in two-terminal configuration

Science.gov (United States)

Cariou, Romain; Benick, Jan; Feldmann, Frank; Höhn, Oliver; Hauser, Hubert; Beutel, Paul; Razek, Nasser; Wimplinger, Markus; Bläsi, Benedikt; Lackner, David; Hermle, Martin; Siefer, Gerald; Glunz, Stefan W.; Bett, Andreas W.; Dimroth, Frank

2018-04-01

Silicon dominates the photovoltaic industry but the conversion efficiency of silicon single-junction solar cells is intrinsically constrained to 29.4%, and practically limited to around 27%. It is possible to overcome this limit by combining silicon with high-bandgap materials, such as III-V semiconductors, in a multi-junction device. Significant challenges associated with this material combination have hindered the development of highly efficient III-V/Si solar cells. Here, we demonstrate a III-V/Si cell reaching similar performances to standard III-V/Ge triple-junction solar cells. This device is fabricated using wafer bonding to permanently join a GaInP/GaAs top cell with a silicon bottom cell. The key issues of III-V/Si interface recombination and silicon's weak absorption are addressed using poly-silicon/SiOx passivating contacts and a novel rear-side diffraction grating for the silicon bottom cell. With these combined features, we demonstrate a two-terminal GaInP/GaAs//Si solar cell reaching a 1-sun AM1.5G conversion efficiency of 33.3%.

Removal of arsenic from water using manganese (III) oxide: Adsorption of As(III) and As(V).

Science.gov (United States)

Babaeivelni, Kamel; Khodadoust, Amid P

2016-01-01

Removal of arsenic from water was evaluated with manganese (III) oxide (Mn2O3) as adsorbent. Adsorption of As(III) and As(V) onto Mn2O3 was favorable according to the Langmuir and Freundlich adsorption equilibrium equations, while chemisorption of arsenic occurred according to the Dubinin-Radushkevich equation. Adsorption parameters from the Langmuir, Freundlich, and Temkin equations showed a greater adsorption and removal of As(III) than As(V) by Mn2O3. Maximum removal of As(III) and As(V) occurred at pH 3-9 and at pH 2, respectively, while removal of As(V) in the pH range of 6-9 was 93% (pH 6) to 61% (pH 9) of the maximum removal. Zeta potential measurements for Mn2O3 in As(III) was likely converted to As(V) solutions indicated that As(III) was likely converted to As(V) on the Mn2O3 surface at pH 3-9. Overall, the effective Mn2O3 sorbent rapidly removed As(III) and As(V) from water in the pH range of 6-9 for natural waters.

Position-controlled epitaxial III-V nanowires on silicon

Energy Technology Data Exchange (ETDEWEB)

Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M [Philips Research Laboratories, Professor Holstlaan 4, 5656 AA Eindhoven (Netherlands); Kavli Institute of NanoScience, Delft University of Technology, PO Box 5046, 2600 GA Delft (Netherlands)

2006-06-14

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires.

Position-controlled epitaxial III-V nanowires on silicon

International Nuclear Information System (INIS)

Roest, Aarnoud L; Verheijen, Marcel A; Wunnicke, Olaf; Serafin, Stacey; Wondergem, Harry; Bakkers, Erik P A M

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction pole figures and cross-sectional transmission electron microscopy. We show preliminary results of two-terminal electrical measurements of III-V nanowires grown on silicon. E-beam lithography was used to predefine the position of the nanowires

III-V nanoelectronics and related surface/interface issues

International Nuclear Information System (INIS)

Hasegawa, Hideki

2003-01-01

The conventional logic gate architecture is not suitable for high-density integration of quantum devices which are non-robust and extremely structure- and charge-sensitive. In this paper, our novel hexagonal binary-decision-diagram (BDD) quantum circuit approach for III-V nanoelectronics is reviewed and related critical surface/interface issues for high-density integration are discussed. First, the basic concept and actual implementation method of our approach are explained, giving examples of novel BDD quantum integrated circuits where nanowire networks are controlled by nanoscale Schottky wrap gates. For high-density integration, growth of embedded sub-10 nm III-V quantum wire networks by selective molecular beam epitaxy (MBE) on patterned substrates is described, including effects of atomic hydrogen irradiation and kinetic control of wire width. The key processing issue lies in understanding and control of nanostructure surfaces/interfaces. Behavior of nanoscale Schottky gates, recent scanning tunneling microscopy (STM)/scanning tunneling spectroscopy (STS) studies of surface states, and successful removal of surface states by MBE-grown silicon interface control layer are discussed

Comprehensive growth and characterization study on highly n-doped InGaAs as a contact layer for quantum cascade laser applications

Science.gov (United States)

Demir, Ilkay; Altuntas, Ismail; Bulut, Baris; Ezzedini, Maher; Ergun, Yuksel; Elagoz, Sezai

2018-05-01

We present growth and characterization studies of highly n-doped InGaAs epilayers on InP substrate by metal organic vapor phase epitaxy to use as an n-contact layer in quantum cascade laser applications. We have introduced quasi two-dimensional electrons between 10 s pulsed growth n-doped InGaAs epilayers to improve both carrier concentration and mobility of structure by applying pulsed growth and doping methods towards increasing the Si dopant concentration in InGaAs. Additionally, the V/III ratio optimization under fixed group III source flow has been investigated with this new method to understand the effects on both crystalline quality and electrical properties of n-InGaAs epilayers. Finally, we have obtained high crystalline quality of n-InGaAs epilayers grown by 10 s pulsed as a contact layer with 2.8 × 1019 cm‑3 carrier concentration and 1530 cm2 V‑1 s‑1 mobility.

III/V nano ridge structures for optical applications on patterned 300 mm silicon substrate

Energy Technology Data Exchange (ETDEWEB)

Kunert, B.; Guo, W.; Mols, Y.; Pantouvaki, M.; Van Campenhout, J.; Langer, R.; Barla, K. [imec, Kapeldreef 75, 3001 Heverlee (Belgium); Tian, B.; Wang, Z.; Shi, Y.; Van Thourhout, D. [Photonics Research Group, Ghent University, Technologiepark-Zwijnaarde 15, 9052 Gent (Belgium)

2016-08-29

We report on an integration approach of III/V nano ridges on patterned silicon (Si) wafers by metal organic vapor phase epitaxy (MOVPE). Trenches of different widths (≤500 nm) were processed in a silicon oxide (SiO{sub 2}) layer on top of a 300 mm (001) Si substrate. The MOVPE growth conditions were chosen in a way to guarantee an efficient defect trapping within narrow trenches and to form a box shaped ridge with increased III/V volume when growing out of the trench. Compressively strained InGaAs/GaAs multi-quantum wells with 19% indium were deposited on top of the fully relaxed GaAs ridges as an active material for optical applications. Transmission electron microcopy investigation shows that very flat quantum well (QW) interfaces were realized. A clear defect trapping inside the trenches is observed whereas the ridge material is free of threading dislocations with only a very low density of planar defects. Pronounced QW photoluminescence (PL) is detected from different ridge sizes at room temperature. The potential of these III/V nano ridges for laser integration on Si substrates is emphasized by the achieved ridge volume which could enable wave guidance and by the high crystal quality in line with the distinct PL.

Blending crystalline/liquid crystalline small molecule semiconductors: A strategy towards high performance organic thin film transistors

Science.gov (United States)

He, Chao; He, Yaowu; Li, Aiyuan; Zhang, Dongwei; Meng, Hong

2016-10-01

Solution processed small molecule polycrystalline thin films often suffer from the problems of inhomogeneity and discontinuity. Here, we describe a strategy to solve these problems through deposition of the active layer from a blended solution of crystalline (2-phenyl[1]benzothieno[3,2-b][1]benzothiophene, Ph-BTBT) and liquid crystalline (2-(4-dodecylphenyl) [1]benzothieno[3,2-b]benzothiophene, C12-Ph-BTBT) small molecule semiconductors with the hot spin-coating method. Organic thin film transistors with average hole mobility approaching 1 cm2/V s, much higher than that of single component devices, have been demonstrated, mainly due to the improved uniformity, continuity, crystallinity, and stronger intermolecular π-π stacking in blend thin films. Our results indicate that the crystalline/liquid crystalline semiconductor blend method is an effective way to enhance the performance of organic transistors.

Rapid arsenic(V)-reduction by fire in schwertmannite-rich soil enhances arsenic mobilisation

DEFF Research Database (Denmark)

Johnston, Scott G.; Bennett, William W.; Burton, Edward D.

2018-01-01

(III) formation (∼90%) within 5–10 min at 400–600 °C, followed by partial re-oxidation to As(V) thereafter. In contrast, heating As(V)-schwertmannite in the absence of soil-organic matter did not cause reduction of As(V) or Fe(III), nor form maghemite; thus highlighting the critical role of organic matter......Arsenic in acid sulfate soil (ASS) landscapes commonly associates with schwertmannite, a poorly crystalline Fe(III) mineral. Fires in ASS landscapes can thermally transform Fe(III) minerals to more crystalline phases, such as maghemite (γFe2O3). Although thermal genesis of maghemite requires...... and hematite at temperatures above 300–400 °C, with some transitory formation of magnetite, and electrons are readily transferred to both Fe(III) and As(V). As(V) reduction to As(III) is influenced by a combination of temperature, heating duration and carbon content and is significantly (P

Vertical group III-V nanowires on si, heterostructures, flexible arrays and fabrication

Science.gov (United States)

Wang, Deli; Soci, Cesare; Bao, Xinyu; Wei, Wei; Jing, Yi; Sun, Ke

2015-01-13

Embodiments of the invention provide a method for direct heteroepitaxial growth of vertical III-V semiconductor nanowires on a silicon substrate. The silicon substrate is etched to substantially completely remove native oxide. It is promptly placed in a reaction chamber. The substrate is heated and maintained at a growth temperature. Group III-V precursors are flowed for a growth time. Preferred embodiment vertical Group III-V nanowires on silicon have a core-shell structure, which provides a radial homojunction or heterojunction. A doped nanowire core is surrounded by a shell with complementary doping. Such can provide high optical absorption due to the long optical path in the axial direction of the vertical nanowires, while reducing considerably the distance over which carriers must diffuse before being collected in the radial direction. Alloy composition can also be varied. Radial and axial homojunctions and heterojunctions can be realized. Embodiments provide for flexible Group III-V nanowire structures. An array of Group III-V nanowire structures is embedded in polymer. A fabrication method forms the vertical nanowires on a substrate, e.g., a silicon substrate. Preferably, the nanowires are formed by the preferred methods for fabrication of Group III-V nanowires on silicon. Devices can be formed with core/shell and core/multi-shell nanowires and the devices are released from the substrate upon which the nanowires were formed to create a flexible structure that includes an array of vertical nanowires embedded in polymer.

Position-controlled epitaxial III-V nanowires on silicon

NARCIS (Netherlands)

Roest, A.L.; Verheijen, M.A.; Wunnicke, O.; Serafin, S.N.; Wondergem, H.J.; Bakkers, E.P.A.M.

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the VLS mechanism with laser ablation as well as metal-organic vapour phase epitaxy. The hetero-epitaxial growth of the III-V nanowires on silicon was confirmed with x-ray diffraction

The Effect of Growth Temperature and V/III Flux Ratio of MOCVD Antimony Based Semiconductors on Growth Rate and Surface Morphology

Directory of Open Access Journals (Sweden)

Ramelan Ari Handono

2017-01-01

Full Text Available Epitaxial Alx Ga1-x Sb layers on GaSb and GaAs substrates have been grown by atmospheric pressure metalorganic chemical vapor deposition using TMAl, TMGa and TMSb. Nomarski microscope and a profiler were employed to examine the surface morphology and growth rate of the samples. We report the effect of growth temperature and V/III flux ratio on growth rate and surface morphology. Growth temperatures in the range of 520°C and 680°C and V/III ratios from 1 to 5 have been investigated. A growth rate activation energy of 0.73 eV was found. At low growth temperatures between 520 and 540°C, the surface morphology is poor due to antimonide precipitates associated with incomplete decomposition of the TMSb. For layers grown on GaAs at 580°C and 600°C with a V/III ratio of 3 a high quality surface morphology is typical, with a mirror-like surface and good composition control. It was found that a suitable growth temperature and V/III flux ratio was beneficial for producing good AlGaSb layers. Undoped AlGaSb grown at 580°C with a V/III flux ratio of 3 at the rate of 3.5 μm/hour shows p-type conductivity with smooth surface morphology

Fast optical in situ spectroscopy in III-V MOVPE

Energy Technology Data Exchange (ETDEWEB)

Kaspari, C.

2007-09-29

This work describes the application of optical in situ measurement techniques (reflectance anisotropy spectroscopy, RAS, and spectroscopic ellipsometry, SE) to processes that are important for the growth of III-V semiconductors like GaAs, InP, InAs and GaP in metal-organic vapour phase epitaxy (MOVPE). Special emphasis is placed on the determination of the free carrier concentration (doping level) and the study of the thermal desorption properties of III-V oxides. A large part of this work is concerned with the development and the construction of a multichannel RAS setup that allows the recording of RAS spectra within fractions of a second. On the basis of benchmark measurements it was shown that the spectral resolution is sufficiently accurate for application in epitaxy. To demonstrate the recording of spectra with high temporal resolution, RAS monolayer oscillations during growth of GaAs were studied and it was shown that the surface changes periodically between a relatively smooth morphology with adsorbed methyl groups (type III) and a stepped, gallium-rich surface (type II). Furthermore the non-reversible process of growing InAs quantum dots on GaAs was studied. It was shown that the multichannel RAS is capable of detecting the 2D-3D transition as well as the following morphological change of the surface at high temporal resolution. For the measurement of the doping level, the relationship between the doping-induced internal electric field and the anisotropy of the sample was studied. To understand the effect of the so-called doping oscillations, a theoretical model was developed. For the investigation of the thermal desorption of the III-V oxides in MOVPE, a number of test series were realised. It was also found that the formation of the reconstructed surface is finished a considerable time after the SE transient indicates stable conditions (no further reduction of the oxide layer). The activation energy for oxide desorption from InAs, GaAs and InP was

Hybrid III-V-on-Si Vertical Cavity laser for Optical Interconnects

DEFF Research Database (Denmark)

Park, Gyeong Cheol; Semenova, Elizaveta; Chung, Il-Sug

2013-01-01

Combining a III-V active material onto the Si platform is an attractive approach for silicon photonics light source. We have developed fabrication methods for novel III-V on Si vertical cavity lasers.......Combining a III-V active material onto the Si platform is an attractive approach for silicon photonics light source. We have developed fabrication methods for novel III-V on Si vertical cavity lasers....

Hybrid III-V/SOI Resonant Cavity Photodetector

DEFF Research Database (Denmark)

Learkthanakhachon, Supannee; Taghizadeh, Alireza; Park, Gyeong Cheol

2016-01-01

A hybrid III-V/SOI resonant cavity photo detector has been demonstrated, which comprises an InP grating reflectorand a Si grating reflector. It can selectively detects an incident light with 1.54-µm wavelength and TM polarization.......A hybrid III-V/SOI resonant cavity photo detector has been demonstrated, which comprises an InP grating reflectorand a Si grating reflector. It can selectively detects an incident light with 1.54-µm wavelength and TM polarization....

Single-layer group IV-V and group V-IV-III-VI semiconductors: Structural stability, electronic structures, optical properties, and photocatalysis

Science.gov (United States)

Lin, Jia-He; Zhang, Hong; Cheng, Xin-Lu; Miyamoto, Yoshiyuki

2017-07-01

Recently, single-layer group III monochalcogenides have attracted both theoretical and experimental interest at their potential applications in photonic devices, electronic devices, and solar energy conversion. Excited by this, we theoretically design two kinds of highly stable single-layer group IV-V (IV =Si ,Ge , and Sn; V =N and P) and group V-IV-III-VI (IV =Si ,Ge , and Sn; V =N and P; III =Al ,Ga , and In; VI =O and S) compounds with the same structures with single-layer group III monochalcogenides via first-principles simulations. By using accurate hybrid functional and quasiparticle methods, we show the single-layer group IV-V and group V-IV-III-VI are indirect bandgap semiconductors with their bandgaps and band edge positions conforming to the criteria of photocatalysts for water splitting. By applying a biaxial strain on single-layer group IV-V, single-layer group IV nitrides show a potential on mechanical sensors due to their bandgaps showing an almost linear response for strain. Furthermore, our calculations show that both single-layer group IV-V and group V-IV-III-VI have absorption from the visible light region to far-ultraviolet region, especially for single-layer SiN-AlO and SnN-InO, which have strong absorption in the visible light region, resulting in excellent potential for solar energy conversion and visible light photocatalytic water splitting. Our research provides valuable insight for finding more potential functional two-dimensional semiconductors applied in optoelectronics, solar energy conversion, and photocatalytic water splitting.

Technological development for super-high efficiency solar cells. Technological development for crystalline compound solar cells (high-efficiency III-V tandem solar cells); Chokokoritsu taiyo denchi no gijutsu kaihatsu. Kessho kagobutsu taiyo denchi no gijutsu kaihatsu (III-V zoku kagobutsu handotai taiyo denchi no gijutsu kaihatsu)

Energy Technology Data Exchange (ETDEWEB)

Tatsuta, M [New Energy and Industrial Technology Development Organization, Tokyo (Japan)

1994-12-01

This paper reports the study results on technological development of III-V compound semiconductor solar cells in fiscal 1994. (1) On development of epitaxial growth technology of lattice mismatching systems, the optimum structure of InGaAs strain intermediate layers was studied for reducing a dislocation density by lattice mismatching of GaAs layer grown on Si substrate and difference in thermal expansion coefficient. The effect of strain layer on dislocation reduction was found only at 250dyne/cm in strain energy. Growth of GaAs layers on the Si substrate treated by hydrofluoric acid at low temperature was attempted by MBE method. As a dislocation distribution was controlled by laying different atoms at hetero-interface, the dislocation density of growing layer surfaces decreased by concentration of dislocation at hetero-interface. (2) On development of high-efficiency tandem cell structure, tunnel junction characteristics, cell formation process and optimum design method of lattice matching tandem cells were studied, while thin film cell formation was basically studied for lattice mismatching tandem cells. 45 figs., 8 tabs.

An ultrahigh vacuum, low-energy ion-assisted deposition system for III-V semiconductor film growth

Science.gov (United States)

Rohde, S.; Barnett, S. A.; Choi, C.-H.

1989-06-01

A novel ion-assisted deposition system is described in which the substrate and growing film can be bombarded with high current densities (greater than 1 mA/sq cm) of very low energy (10-200 eV) ions. The system design philosophy is similar to that used in III-V semiconductor molecular-beam epitaxy systems: the chamber is an all-metal ultrahigh vacuum system with liquid-nitrogen-cooled shrouds, Knudsen-cell evaporation sources, a sample insertion load-lock, and a 30-kV reflection high-energy electron diffraction system. III-V semiconductor film growth is achieved using evaporated group-V fluxes and group-III elemental fluxes sputtered from high-purity targets using ions extracted from a triode glow discharge. Using an In target and an As effusion cell, InAs deposition rates R of 2 microns/h have been obtained. Epitaxial growth of InAs was observed on both GaSb(100) and Si(100) substrates.

Placement of a crystalline lens and intraocular lens: Retinal image quality.

Science.gov (United States)

Siedlecki, Damian; Nowak, Jerzy; Zajac, Marek

2006-01-01

The influence of changes of both crystalline lens and intraocular lens (IOL) misalignment on the retinal image quality was investigated. The optical model of the eye used in investigations was the Liou-Brennan model, which is commonly considered as one of the most anatomically accurate. The original crystalline lens from this model was replaced with an IOL, made of rigid polymethylmethacrylate, in a way that recommend obligatory procedures. The modifications that were made both for crystalline lens and IOL were the longitudinal, the transversal, and the angular displacement.

Zwitterion-functionalized polymer microspheres as a sorbent for solid phase extraction of trace levels of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) prior to their determination by ICP-MS.

Science.gov (United States)

Jia, Xiaoyu; Gong, Dirong; Zhao, Junyi; Ren, Hongyun; Wang, Jiani; Zhang, Xian

2018-03-19

This paper describes the preparation of zwitterion-functionalized polymer microspheres (ZPMs) and their application to simultaneous enrichment of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) from environmental water samples. The ZPMs were prepared by emulsion copolymerization of ethyl methacrylate, 2-diethylaminoethyl methacrylate and triethylene glycol dimethyl acrylate followed by modification with 1,3-propanesultone. The components were analyzed by elemental analyses as well as Fourier transform infrared spectroscopy, and the structures were characterized by scanning electron microscopy and transmission electron microscopy. The ZPMs were packed into a mini-column for on-line solid-phase extraction (SPE) of the above metal ions. Following extraction with 40 mM NH 4 NO 3 and 0.5 M HNO 3 solution, the ions were quantified by ICP-MS. Under the optimized conditions, the enrichment factors (from a 40 mL sample) are up to 60 for the ions V(V), As(III), Sb(III) and Hg(II), and 55 for Cr(III) and Sn(IV). The detection limits are 1.2, 3.4, 1.0, 3.7, 2.1 and 1.6 ng L -1 for V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II), respectively, and the relative standard deviations (RSDs) are below 5.2%. The feasibility and accuracy of the method were validated by successfully analyzing six certified reference materials as well as lake, well and river waters. Graphical abstract Zwitterion-functionalized polymer microspheres (ZPMs) were prepared and packed into a mini-column for on-line solid-phase extraction (SPE) via pump 1. Then V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) ions in environmental waters were eluted and submitted to ICP-MS via pump 2.

III-V/Si Tandem Cells Utilizing Interdigitated Back Contact Si Cells and Varying Terminal Configurations: Preprint

Energy Technology Data Exchange (ETDEWEB)

Schnabel, Manuel; Klein, Talysa R.; Jain, Nikhil; Essig, Stephanie; Schulte-Huxel, Henning; Warren, Emily; van Hest, Maikel F. A. M.; Geisz, John; Stradins, Paul; Tamboli, Adele; Rienacker, Michael; Merkle, Agnes; Schmidt, Jan; Brendel, Rolf; Peibst, Robby

2017-07-11

Solar cells made from bulk crystalline silicon (c-Si) dominate the market, but laboratory efficiencies have stagnated because the current record efficiency of 26.3% is already very close to the theoretical limit of 29.4% for a single-junction c-Si cell. In order to substantially boost the efficiency of Si solar cells we have been developing stacked III-V/Si tandem cells, recently attaining efficiencies above 32% in four-terminal configuration. In this contribution, we use state-of-the-art III-V cells coupled with equivalent circuit simulations to compare four-terminal (4T) to three- and two-terminal (3T, 2T) operation. Equivalent circuit simulations are used to show that tandem cells can be operated just as efficiently using three terminals as with four terminals. However, care must be taken not to overestimate 3T efficiency, as the two circuits used to extract current interact, and a method is described to accurately determine this efficiency. Experimentally, a 4T GaInP/Si tandem cell utilizing an interdigitated back contact cell is shown, exhibiting a 4T efficiency of 31.5% and a 2T efficiency of 28.1%. In 3T configuration, it is used to verify the finding from simulation that 3T efficiency is overestimated when interactions between the two circuits are neglected. Considering these, a 3T efficiency approaching the 4T efficiency is found, showing that 3T operation is efficient, and an outlook on fully integrated high-efficiency 3T and 2T tandem cells is given.

Transferable tight binding model for strained group IV and III-V heterostructures

Science.gov (United States)

Tan, Yaohua; Povolotskyi, Micheal; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

Modern semiconductor devices have reached critical device dimensions in the range of several nanometers. For reliable prediction of device performance, it is critical to have a numerical efficient model that are transferable to material interfaces. In this work, we present an empirical tight binding (ETB) model with transferable parameters for strained IV and III-V group semiconductors. The ETB model is numerically highly efficient as it make use of an orthogonal sp3d5s* basis set with nearest neighbor inter-atomic interactions. The ETB parameters are generated from HSE06 hybrid functional calculations. Band structures of strained group IV and III-V materials by ETB model are in good agreement with corresponding HSE06 calculations. Furthermore, the ETB model is applied to strained superlattices which consist of group IV and III-V elements. The ETB model turns out to be transferable to nano-scale hetero-structure. The ETB band structures agree with the corresponding HSE06 results in the whole Brillouin zone. The ETB band gaps of superlattices with common cations or common anions have discrepancies within 0.05eV.

Analysis of novel silicon and III-V solar cells by simulation and experiment; Analyse neuartiger Silizium- und III-V-Solarzellen mittels Simulation und Experiment

Energy Technology Data Exchange (ETDEWEB)

Hermle, Martin

2008-11-27

This work presents various simulation studies of silicon and III-V solar cells. For standard silicon solar cells, one of the critical parameters to obtain good performance, is the rear side recombination velocity. The optical and electrical differences of the different cell structures were determined. The optical differences and the effective recombination velocity Sback of the different rear side structures for 1 Ohmcm material were extracted. Beside standard silicon solar cells, back junction silicon solar cells were investigated. Especially the influence of the front surface field and the electrical shading due to the rear side, was investigated. In the last two chapters, III-V solar cells were analysed. For the simulation of III-V multi-junction solar cells, the simulation of the tunneldiode is the basic prerequisite. In this work, the numerical calibration of an GaAs tunneldiode was achieved by using an non-local tunnel model. Using this model, it was possible to successfully simulate a III-V tandem solar cell. The last chapter deals with an optimization of the III-V 3-junction cell for space applications. Especially the influence of the GaAs middle cell was investigated. Due to structural changes, the end-of-life efficiency was drastically increased.

The coupling of thermochemistry and phase diagrams for group III-V semiconductor systems. Final report

Energy Technology Data Exchange (ETDEWEB)

Anderson, T.J.

1998-07-21

The project was directed at linking the thermochemical properties of III-V compound semiconductors systems with the reported phase diagrams. The solid-liquid phase equilibrium problem was formulated and three approaches to calculating the reduced standard state chemical potential were identified and values were calculated. In addition, thermochemical values for critical properties were measured using solid state electrochemical techniques. These values, along with the standard state chemical potentials and other available thermochemical and phase diagram data, were combined with a critical assessment of selected III-V systems. This work was culminated with a comprehensive assessment of all the III-V binary systems. A novel aspect of the experimental part of this project was the demonstration of the use of a liquid encapsulate to measure component activities by a solid state emf technique in liquid III-V systems that exhibit high vapor pressures at the measurement temperature.

Controlling the emission wavelength in group III-V semiconductor laser diodes

KAUST Repository

Ooi, Boon S.

2016-12-29

Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III-V semiconductor quantum wells. The group III-V semiconductor can include AlSb, AlAs, Aln, AlP, BN, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, and InP, and group III-V ternary semiconductors alloys such as AlxGai.xAs. The methods can results in a blue shifting of about 20 meV to 350 meV, which can be used for example to make group III-V semiconductor quantum well laser diodes with an emission that is orange or yellow. Methods of making semiconductor quantum well laser diodes and semiconductor quantum well laser diodes made therefrom are also provided.

Three-Dimensional Reduced Graphene Oxide Coupled with Mn3O4 for Highly Efficient Removal of Sb(III) and Sb(V) from Water.

Science.gov (United States)

Zou, Jian-Ping; Liu, Hui-Long; Luo, Jinming; Xing, Qiu-Ju; Du, Hong-Mei; Jiang, Xun-Heng; Luo, Xu-Biao; Luo, Sheng-Lian; Suib, Steven L

2016-07-20

Highly porous, three-dimensional (3D) nanostructured composite adsorbents of reduced graphene oxides/Mn3O4 (RGO/Mn3O4) were fabricated by a facile method of a combination of reflux condensation and solvothermal reactions and systemically characterized. The as-prepared RGO/Mn3O4 possesses a mesoporous 3D structure, in which Mn3O4 nanoparticles are uniformly deposited on the surface of the reduced graphene oxide. The adsorption properties of RGO/Mn3O4 to antimonite (Sb(III)) and antimonate (Sb(V)) were investigated using batch experiments of adsorption isotherms and kinetics. Experimental results show that the RGO/Mn3O4 composite has fast liquid transport and superior adsorption capacity toward antimony (Sb) species in comparison to six recent adsorbents reported in the literature and summarized in a table in this paper. Theoretical maximum adsorption capacities of RGO/Mn3O4 toward Sb(III) and Sb(V) are 151.84 and 105.50 mg/g, respectively, modeled by Langmuir isotherms. The application of RGO/Mn3O4 was demonstrated by using drinking water spiked with Sb (320 μg/L). Fixed-bed column adsorption experiments indicate that the effective breakthrough volumes were 859 and 633 mL bed volumes (BVs) for the Sb(III) and Sb(V), respectively, until the maximum contaminant level of 5 ppb was reached, which is below the maximum limits allowed in drinking water according to the most stringent regulations. The advantages of being nontoxic, highly stable, and resistant to acid and alkali and having high adsorption capacity toward Sb(III) and Sb(V) confirm the great potential application of RGO/Mn3O4 in Sb-spiked water treatment.

Photoelectrochemistry of III-V epitaxial layers and nanowires for solar energy conversion

Science.gov (United States)

Parameshwaran, Vijay; Enck, Ryan; Chung, Roy; Kelley, Stephen; Sampath, Anand; Reed, Meredith; Xu, Xiaoqing; Clemens, Bruce

2017-05-01

III-V materials, which exhibit high absorption coefficients and charge carrier mobility, are ideal templates for solar energy conversion applications. This work describes the photoelectrochemistry research in several IIIV/electrolyte junctions as an enabler for device design for solar chemical reactions. By designing lattice-matched epitaxial growth of InGaP and GaP on GaAs and Si, respectively, extended depletion region electrodes achieve photovoltages which provide an additional boost to the underlying substrate photovoltage. The InGaP/GaAs and GaP/Si electrodes drive hydrogen evolution currents under aqueous conditions. By using nanowires of InN and InP under carefully controlled growth conditions, current and capacitance measurements are obtained to reveal the nature of the nanowire-electrolyte interface and how light is translated into photocurrent for InP and a photovoltage in InN. The materials system is expanded into the III-V nitride semiconductors, in which it is shown that varying the morphology of GaN on silicon yields insights to how the interface and light conversion is modulated as a basis for future designs. Current extensions of this work address growth and tuning of the III-V nitride electrodes with doping and polarization engineering for efficient coupling to solar-driven chemical reactions, and rapid-throughput methods for III-V nanomaterials synthesis in this materials space.

Photon confinement in high-efficiency, thin-film III-V solar cells obtained by epitaxial lift-off

International Nuclear Information System (INIS)

Schermer, J.J.; Bauhuis, G.J.; Mulder, P.; Haverkamp, E.J.; Deelen, J. van; Niftrik, A.T.J. van; Larsen, P.K.

2006-01-01

Using the epitaxial lift-off (ELO) technique, a III-V device structure can be separated from its GaAs substrate by selective wet etching of a thin release layer. The thin-film structures obtained by the ELO process can be cemented or van der Waals bonded on arbitrary smooth surface carriers for further processing. It is shown that the ELO method, initially able to separate millimetre-sized GaAs layers with a lateral etch rate of about 1 mm/h, has been developed to a process capable to free the entire 2-in. epitaxial structures from their substrates with etch rates up to 30 mm/h. With these characteristics the method has a large potential for the production of high efficiency thin-film solar cells. By choosing the right deposition and ELO strategy, the thin-film III-V cells can be adequately processed on both sides allowing for an entire range of new cell structures. In the present work, the performance of semi-transparent bifacial solar cells, produced by the deposition of metal grid contacts on both sides, was evaluated. Reflection of light at the rear side of the bifacial GaAs solar cells was found to result in an enhanced collection probability of the photon-induced carriers compared to that of regular III-V cells on a GaAs substrate. To enhance this effect, thin-film GaAs cells with gold mirror back contacts were prepared. Even in their present premature stage of development, these single-junction thin-film cells reached a record efficiency of 24.5% which is already very close to the 24.9% efficiency that was obtained with a regular GaAs cell on a GaAs substrate. From this it could be concluded that, as a result of the photon confinement, ELO cells require a significantly thinner base layer than regular GaAs cells while at the same time they have the potential to reach a higher efficiency

Sb{sup III} - Sb{sup V} Exchange Reaction in Hydrochloric: Acid Solutions; Echange Sb{sup III}-Sb{sup V} dans des Solutions d'Acide Chlorhydrique; Reaktsiya obmena Sb(III) - Sb(V) v rastvorakh khloristovodorodnoj kisloty; Intercambio Sb{sup III}-Sb{sup V} en Soluciones de HCl

Energy Technology Data Exchange (ETDEWEB)

Kambara, T.; Yamaguchi, K.; Yasuba, S. [Shizuoka University, Shizuoka City (Japan)

1965-10-15

The exchange reaction of Sb{sup III} - Sb{sup V} in solutions of low HCl concentrations was studied using {sup 124}Sb as a tracer. The effects of HCl concentrations and chemical forms of antimony on the exchange rate were investigated. The HCl concentrations of the antimony solutions ((Sb{sup III}) =(Sb{sup V}) = 6.8 x 10{sup -4}M) were changed from 0.8 to 4.0M and the half-time for the exchange was measured by plotting log (1 - F) versus time t to calculate the exchange rate assuming the second-ordet reaction. It was found that the exchange rate was sharply increased with the increase of HCl concentrations (at 25 Degree-Sign C, from 0.8 to 2.0M) and at 2.0M HCl concentration the rate reached the maximum, from which the rate was decreased with the increase of HCl concentrations (at 25 Degree-Sign C, from 2.0 to 4.0M). Two sorts of Sb{sup V} species were used for our investigations, i.e. one was used directly after the dilution of 10M HCl Sb{sup V} solution with water and the other was used after 24 hours standing at room temperature from the dilution. (The Sb{sup III} species were also kept standing after preparation from 10M HCl Sb{sup III} solution.) In both cases the maximum rates were found to exist at 2.0M HCl concentration. The rate R{sub 1} for the former (directly after dilution) was 4.5 x 10{sup -6} mole litre{sup -1} min{sup -1} and the rate R{sub 2} for the latter (24 hours standing) was 1.2 x 10{sup -}{sub 6} mole litre. Also the activation energy for these cases was found to be 12.2 kcal/mole and 19.1 kcal/mole. By spectrophotometric studies, the Sb{sup V} species of the former type were found to be mainly consisting of SbCl{sup -}{sub 6} and the species of the latter type to be of SbCl{sub 4}(OH){sup -}{sub 2}, etc. Besides these facts the form of Sb{sup III} species was found to have no influence on the exchange rate. A much sharper increase of the exchange rate was observed when the HCl concentration of the antimony solution was fixed at 0.8M and

Direct Growth of High-Quality InP Layers on GaAs Substrates by MOCVD

Directory of Open Access Journals (Sweden)

K. F. Yarn

2003-01-01

group V partial pressure, growth rate and V/III ratios. A mirror-like, uniform surface and high crystal quality of the metamorphic buffer layer directly grown on a GaAs substrate can be achieved. Finally, to investigate the performance of the metamorphic microwave devices, we also fabricate the InAlAs/InGaAs metamorphic HEMT on GaAs substrates.

Fabrications and application of single crystalline GaN for high-performance deep UV photodetectors

Energy Technology Data Exchange (ETDEWEB)

Velazquez, R.; Rivera, M.; Feng, P., E-mail: p.feng@upr.edu [Department of Physics, College of Natural Sciences, University of Puerto Rico, San Juan, 00936-8377, PR/USA (Puerto Rico); Aldalbahi, A. [Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)

2016-08-15

High-quality single crystalline Gallium Nitride (GaN) semiconductor has been synthesized using molecule beam epitaxy (MBE) technique for development of high-performance deep ultraviolet (UV) photodetectors. Thickness of the films was estimated by using surface profile meter and scanning electron microscope. Electronic states and elemental composition of the films were obtained using Raman scattering spectroscopy. The orientation, crystal structure and phase purity of the films were examined using a Siemens x-ray diffractometer radiation. The surface microstructure was studied using high resolution scanning electron microscopy (SEM). Two types of metal pairs: Al-Al, Al-Cu or Cu-Cu were used for interdigital electrodes on GaN film in order to examine the Schottky properties of the GaN based photodetector. The characterizations of the fabricated prototype include the stability, responsivity, response and recovery times. Typical time dependent photoresponsivity by switching different UV light source on and off five times for each 240 seconds at a bias of 2V, respectively, have been obtained. The detector appears to be highly sensitive to various UV wavelengths of light with very stable baseline and repeatability. The obtained photoresponsivity was up to 354 mA/W at the bias 2V. Higher photoresponsivity could be obtained if higher bias was applied but it would unavoidably result in a higher dark current. Thermal effect on the fabricated GaN based prototype was discussed.

III-V Ultra-Thin-Body InGaAs/InAs MOSFETs for Low Standby Power Logic Applications

Science.gov (United States)

Huang, Cheng-Ying

As device scaling continues to sub-10-nm regime, III-V InGaAs/InAs metal- oxide-semiconductor ?eld-e?ect transistors (MOSFETs) are promising candidates for replacing Si-based MOSFETs for future very-large-scale integration (VLSI) logic applications. III-V InGaAs materials have low electron effective mass and high electron velocity, allowing higher on-state current at lower VDD and reducing the switching power consumption. However, III-V InGaAs materials have a narrower band gap and higher permittivity, leading to large band-to-band tunneling (BTBT) leakage or gate-induced drain leakage (GIDL) at the drain end of the channel, and large subthreshold leakage due to worse electrostatic integrity. To utilize III-V MOSFETs in future logic circuits, III-V MOSFETs must have high on-state performance over Si MOSFETs as well as very low leakage current and low standby power consumption. In this dissertation, we will report InGaAs/InAs ultra-thin-body MOSFETs. Three techniques for reducing the leakage currents in InGaAs/InAs MOSFETs are reported as described below. 1) Wide band-gap barriers: We developed AlAs0.44Sb0.56 barriers lattice-match to InP by molecular beam epitaxy (MBE), and studied the electron transport in In0.53Ga0.47As/AlAs 0.44Sb0.56 heterostructures. The InGaAs channel MOSFETs using AlAs0.44Sb0.56 bottom barriers or p-doped In0.52 Al0.48As barriers were demonstrated, showing significant suppression on the back barrier leakage. 2) Ultra-thin channels: We investigated the electron transport in InGaAs and InAs ultra-thin quantum wells and ultra-thin body MOSFETs (t ch ~ 2-4 nm). For high performance logic, InAs channels enable higher on-state current, while for low power logic, InGaAs channels allow lower BTBT leakage current. 3) Source/Drain engineering: We developed raised InGaAs and recessed InP source/drain spacers. The raised InGaAs source/drain spacers improve electrostatics, reducing subthreshold leakage, and smooth the electric field near drain, reducing

Comparison of high pressure homogenization and stirred bead milling for the production of nano-crystalline suspensions.

Science.gov (United States)

Nakach, Mostafa; Authelin, Jean-René; Perrin, Marc-Antoine; Lakkireddy, Harivardhan Reddy

2018-05-19

Currently, the two technologies primarily used for the manufacturing of nano-crystalline suspensions using top down process (i.e. wet milling) are high pressure homogenization (HPH) and stirred bead milling (SBM). These two technologies are based upon different mechanisms, i.e., cavitation forces for HPH and shear forces for stirred bead milling. In this article, the HPH and SBM technologies are compared in terms of the impact of the suspension composition the process parameters and the technological configuration on milling performances and physical quality of the suspensions produced. The data suggested that both HPH and SBM are suitable for producing nano-crystalline suspensions, although SBM appeared more efficient than HPH, since the limit of milling (d 50 ) for SBM was found to be lower than that obtained with HPH (100 nm vs 200 nm). For both these technologies, regardless of the process parameters used for milling and the scale of manufacturing, the relationship of d 90 versus d 50 could be described by a unique master curve (technology signature of milling pathway) outlining that the HPH leads to more uniform particle size distribution as compared to SBM. Copyright © 2018 Elsevier B.V. All rights reserved.

Liquid crystallinity driven highly aligned large graphene oxide composites

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyung Eun; Oh, Jung Jae; Yun, Taeyeong [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701 (Korea, Republic of); Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Kim, Sang Ouk, E-mail: sangouk.kim@kaist.ac.kr [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701 (Korea, Republic of); Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of)

2015-04-15

Graphene is an emerging graphitic carbon materials, consisting of sp{sup 2} hybridized two dimensinal honeycomb structure. It has been widely studied to incorporate graphene with polymer to utilize unique property of graphene and reinforce electrical, mechanical and thermal property of polymer. In composite materials, orientation control of graphene significantly influences the property of composite. Until now, a few method has been developed for orientation control of graphene within polymer matrix. Here, we demonstrate facile fabrication of high aligned large graphene oxide (LGO) composites in polydimethylsiloxane (PDMS) matrix exploiting liquid crystallinity. Liquid crystalline aqueous dispersion of LGO is parallel oriented within flat confinement geometry. Freeze-drying of the aligned LGO dispersion and subsequent infiltration with PDMS produce highly aligned LGO/PDMS composites. Owing to the large shape anisotropy of LGO, liquid crystalline alignment occurred at low concentration of 2 mg/ml in aqueous dispersion, which leads to the 0.2 wt% LGO loaded composites. - Graphical abstract: Liquid crystalline LGO aqueous dispersions are spontaneous parallel aligned between geometric confinement for highly aligned LGO/polymer composite fabrication. - Highlights: • A simple fabrication method for highly aligned LGO/PDMS composites is proposed. • LGO aqueous dispersion shows nematic liquid crystalline phase at 0.8 mg/ml. • In nematic phase, LGO flakes are highly aligned by geometric confinement. • Infiltration of PDMS into freeze-dried LGO allows highly aligned LGO/PDMS composites.

Methods for enhancing P-type doping in III-V semiconductor films

Science.gov (United States)

Liu, Feng; Stringfellow, Gerald; Zhu, Junyi

2017-08-01

Methods of doping a semiconductor film are provided. The methods comprise epitaxially growing the III-V semiconductor film in the presence of a dopant, a surfactant capable of acting as an electron reservoir, and hydrogen, under conditions that promote the formation of a III-V semiconductor film doped with the p-type dopant. In some embodiments of the methods, the epitaxial growth of the doped III-V semiconductor film is initiated at a first hydrogen partial pressure which is increased to a second hydrogen partial pressure during the epitaxial growth process.

Interface state density evaluation of high quality hetero-epitaxial 3C–SiC(0 0 1) for high-power MOSFET applications

Energy Technology Data Exchange (ETDEWEB)

Anzalone, R., E-mail: ruggero.anzalone@imm.cnr.it; Privitera, S.; Camarda, M.; Alberti, A.; Mannino, G.; Fiorenza, P.; Di Franco, S.; La Via, F.

2015-08-15

Graphical abstract: Figure shows the normalized capacitance (C/C{sub OX}) versus voltage (V) for the MOS capacitors on 3 μm, 7 μm thick 3C–SiC films and silicon (as reference), respectively. The shift of the curve respect to the reference is due to the presence of fixed and/or trapped charge in the oxide and interface trapped charge, due to the presence of interface states of density D{sub it}, located at the semiconductor/oxide interface. - Highlights: • We analyzed the flat-band voltage shift for different semiconductor epi-thickness. • The interface state density as a function of epi-defects was evaluated. • We observed the relationship between XRD and C–V results. • Epitaxial thickness influence on interface state density was evaluated. - Abstract: The effects of the crystal quality and surface morphology on the electrical properties of MOS capacitors have been studied in devices manufactured on 3C–SiC epitaxial layers grown on silicon (1 0 0) substrate. The interface state density, which represents one of the most important parameters, has been determined through capacitance measurements. A cross-correlation between high resolution X-ray diffraction, AFM analysis and electrical conductance measurements has allowed to determine the relationship between the crystalline quality and the interface state density. A decrease of the interface state density down to about 10{sup 11} cm{sup −2} eV{sup −1} was observed with improving the crystalline quality.

Progress in III-V materials technology

Science.gov (United States)

Grant, Ian R.

2004-12-01

Compound semiconductors, in the form of GaAs and InP have achieved major commercial significance in areas of application such as mobile communications, displays and telecoms and offer a versatility of function beyond the capabilities of Si. III-V compounds, and in particular GaAs, have since their early development been the subject of defence related interest. Support from this sector established the basic materials technologies and nurtured development up until their commercial breakthrough into consumer products. GaAs, for example, now provides essential components for mobile phones and CD / DVD players. An overview is presented of the crystal growth and processing methods used in the manufacture of these materials. Current state of the art characteristics on crystal form and quality are discussed, together with the evolution of single crystal growth techniques. Consideration is given to how these principal compounds together with the minor materials, InSb, GaSb and InAs are employed in diverse applications over a broad spectral range, together with information on markets and future perspectives.

Structure of metal-rich (001) surfaces of III-V compound semiconductors

DEFF Research Database (Denmark)

Kumpf, C.; Smilgies, D.; Landemark, E.

2001-01-01

The atomic structure of the group-III-rich surface of III-V semiconductor compounds has been under intense debate for many years, yet none of the models agrees with the experimental data available. Here we present a model for the three-dimensional structure of the (001)-c(8x2) reconstruction on In......(8 x 2) reconstructions of III-V semiconductor surfaces contain the same essential building blocks....

Low-cost high-quality crystalline germanium based flexible devices

KAUST Repository

Nassar, Joanna M.

2014-06-16

High performance flexible electronics promise innovative future technology for various interactive applications for the pursuit of low-cost, light-weight, and multi-functional devices. Thus, here we show a complementary metal oxide semiconductor (CMOS) compatible fabrication of flexible metal-oxide-semiconductor capacitors (MOSCAPs) with high-κ/metal gate stack, using a physical vapor deposition (PVD) cost-effective technique to obtain a high-quality Ge channel. We report outstanding bending radius ~1.25 mm and semi-transparency of 30%.

Low-cost high-quality crystalline germanium based flexible devices

KAUST Repository

Nassar, Joanna M.; Hussain, Aftab M.; Rojas, Jhonathan Prieto; Hussain, Muhammad Mustafa

2014-01-01

High performance flexible electronics promise innovative future technology for various interactive applications for the pursuit of low-cost, light-weight, and multi-functional devices. Thus, here we show a complementary metal oxide semiconductor (CMOS) compatible fabrication of flexible metal-oxide-semiconductor capacitors (MOSCAPs) with high-κ/metal gate stack, using a physical vapor deposition (PVD) cost-effective technique to obtain a high-quality Ge channel. We report outstanding bending radius ~1.25 mm and semi-transparency of 30%.

Effects of crystalline quality and electrode material on fatigue in Pb(Zr,Ti)O3 thin film capacitors

Science.gov (United States)

Lee, J.; Johnson, L.; Safari, A.; Ramesh, R.; Sands, T.; Gilchrist, H.; Keramidas, V. G.

1993-07-01

Pb(Zr(0.52)Ti(0.48))O3 (PZT)/Y1Ba2Cu3O(x) (YBCO) heterostructures were grown by pulsed laser deposition, in which PZT films were epitaxial, highly oriented, or polycrystalline. These PZT films were obtained by varying the deposition temperature from 550 to 760 C or by using various substrates such as SrTiO3 (100), MgO (100), and r-plane sapphire. PZT films with Pt top electrodes exhibited large fatigue with 35-50 percent loss of the remanent polarization after 10 exp 9 cycles, depending on the crystalline quality. Polycrystalline films showed better fatigue resistance than epitaxial or highly oriented films. However, PZT films with both top and bottom YBCO electrodes had significantly improved fatigue resistance for both epitaxial and polycrystalline films. Electrode material seems to be a more important parameter in fatigue than the crystalline quality of the PZT films.

Design and Characterisation of III-V Semiconductor Nanowire Lasers

Science.gov (United States)

Saxena, Dhruv

The development of small, power-efficient lasers underpins many of the technologies that we utilise today. Semiconductor nanowires are promising for miniaturising lasers to even smaller dimensions. III-V semiconductors, such as Gallium Arsenide (GaAs) and Indium Phosphide (InP), are the most widely used materials for optoelectronic devices and so the development of nanowire lasers based on these materials is expected to have technologically significant outcomes. This PhD dissertation presents a comprehensive study of the design of III-V semiconductor nanowire lasers, with bulk and quantum confined active regions. Based on the design, various III-V semiconductor nanowire lasers are demonstrated, namely, GaAs nanowire lasers, GaAs/AlGaAs multi-quantum well (MQW) nanowire lasers and InP nanowire lasers. These nanowire lasers are shown to operate at room temperature, have low thresholds, and lase from different transverse modes. The structural and optoelectronic quality of nanowire lasers are characterised via electron microscopy and photoluminescence spectroscopic techniques. Lasing is characterised in all these devices by optical pumping. The lasing characteristics are analysed by rate equation modelling and the lasing mode(s) in these devices is characterised by threshold gain modelling, polarisation measurements and Fourier plane imaging. Firstly, GaAs nanowire lasers that operate at room temperature are demonstrated. This is achieved by determining the optimal nanowire diameter to reduce threshold gain and by passivating nanowires to improve their quantum efficiency (QE). High-quality surface passivated GaAs nanowires of suitable diameters are grown. The growth procedure is tailored to improve both QE and structural uniformity of nanowires. Room-temperature lasing is demonstrated from individual nanowires and lasing is characterised to be from TM01 mode by threshold gain modelling. To lower threshold even further, nanowire lasers with GaAs/AlGaAs coaxial multi

Comparison of the quality of the chest film between digital radiography and conventional high kV radiography

International Nuclear Information System (INIS)

Zeng Qingsi; Cen Renli; Chen Ling; He Jianxun; Lin Hanfei

2003-01-01

Objective: To evaluate the quality and usefulness of direct digital radiography system in roentgenogram of chest in clinical practice. Methods: 1000 cases of chest roentgenograms with digital radiography and high kV conventional radiography were selected for analysis by 3 senior radiologists. Results: 1. With digital radiography system, the quality of chest film was assessed as grade A in 50.6%, grade B in 38.5%, grade C in 10.9%, and no waste film. 2. With conventional high kV radiography, the quality of chest film was assessed as grade A in 41.1%, grade B in 44.1%, grade C in 13.3%, and waste film in 1.5%. The direct digital radiography was statistically superior to the conventional high kV radiography. 3. The fine structure of the lungs could be revealed in 100.0% of chest roentgenogram with direct digital radiograph system, which was significantly higher than that acquired with the conventional high KV radiography (78.6%, P < 0.001). Conclusion: Direct digital radiography could provide the chest film with better quality than that with the conventional high kV radiography. The direct digital radiography system is easy to operate, fast in capturing imaging and could provide post-processing techniques, which will facilitate the accurate diagnosis of chest radiography

Manganese associated nanoparticles agglomerate of iron(III) oxide: synthesis, characterization and arsenic(III) sorption behavior with mechanism.

Science.gov (United States)

Gupta, Kaushik; Maity, Arjun; Ghosh, Uday Chand

2010-12-15

Three samples of manganese associated hydrous iron(III) oxide (MNHFO), prepared by incinerating metal hydroxide precipitate at T (± 5)=90, 300 and 600°C, showed increase of crystalline nature in XRD patterns with decreasing As(III) removal percentages. TEM images showed the increase of crystallinity from sample-1 (MNHFO-1) to sample-3 (MNHFO-3). Dimensions (nm) of particles estimated were 5.0, 7.0 and 97.5. Optimization of pH indicated that MNHFO-1 could remove aqueous As(III) efficiently at pH between 3.0 and 7.0. Kinetic and equilibrium data of reactions under the experimental conditions described the pseudo-second order and the Langmuir isotherm equations very well, respectively. The Langmuir capacity (q(m)) estimated was 691.04 mmol kg(-1). The values of enthalpy, Gibb's free energy and entropy changes (ΔH(0)=+23.23 kJ mol(-1), ΔG(0)=-3.43 to -7.20 kJ mol(-1) at T=283-323K, ΔS(0)=+0.094 kJ mol(-1)K(-1)) suggested that the reaction was endothermic, spontaneous and took place with increasing entropy. The As(III) sorbed by MNHFO-1 underwent surface oxidation to As(V), and evidences appeared from the XPS and FTIR investigations. MNHFO-1 packed column (internal diameter: 1.0 cm, height: 3.7 cm) filtered 11.5 dm(3) groundwater (105 μg As dm(-3)) with reducing arsenic concentration to ≤ 10 μg dm(-3). Copyright © 2010 Elsevier B.V. All rights reserved.

The mechanisms of detoxification of As(III), dimethylarsinic acid (DMA) and As(V) in the microalga Chlorella vulgaris.

Science.gov (United States)

Pantoja Munoz, L; Purchase, D; Jones, H; Raab, A; Urgast, D; Feldmann, J; Garelick, H

2016-06-01

The response of Chlorella vulgaris when challenged by As(III), As(V) and dimethylarsinic acid (DMA) was assessed through experiments on adsorption, efflux and speciation of arsenic (reduction, oxidation, methylation and chelation with glutathione/phytochelatin [GSH/PC]). Our study indicates that at high concentrations of phosphate (1.62mM of HPO4(2-)), upon exposure to As(V), cells are able to shift towards methylation of As(V) rather than PC formation. Treatment with As(V) caused a moderate decrease in intracellular pH and a strong increase in the concentration of free thiols (GSH). Passive surface adsorption was found to be negligible for living cells exposed to DMA and As(V). However, adsorption of As(III) was observed to be an active process in C. vulgaris, because it did not show saturation at any of the exposure periods. Chelation of As(III) with GS/PC and to a lesser extent hGS/hPC is a major detoxification mechanism employed by C. vulgaris cells when exposed to As(III). The increase of bound As-GS/PC complexes was found to be strongly related to an increase in concentration of As(III) in media. C. vulgaris cells did not produce any As-GS/PC complex when exposed to As(V). This may indicate that a reduction step is needed for As(V) complexation with GSH/PC. C. vulgaris cells formed DMAS(V)-GS upon exposure to DMA independent of the exposure period. As(III) triggers the formation of arsenic complexes with PC and homophytochelatins (hPC) and their compartmentalisation to vacuoles. A conceptual model was devised to explain the mechanisms involving ABCC1/2 transport. The potential of C. vulgaris to bio-remediate arsenic from water appeared to be highly selective and effective without the potential hazard of reducing As(V) to As(III), which is more toxic to humans. Copyright © 2016 Elsevier B.V. All rights reserved.

Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications

International Nuclear Information System (INIS)

McDaniel, Martin D.; Ngo, Thong Q.; Ekerdt, John G.; Hu, Chengqing; Jiang, Aiting; Yu, Edward T.; Lu, Sirong; Smith, David J.; Posadas, Agham; Demkov, Alexander A.

2015-01-01

The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO 3 (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10 −5 A/cm 2 at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (D it ) is estimated to be as low as ∼2 × 10 12  cm −2  eV −1 under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased D it value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications

Recovery Act : Near-Single-Crystalline Photovoltaic Thin Films on Polycrystalline, Flexible Substrates

Energy Technology Data Exchange (ETDEWEB)

Venkat Selvamanickam; Alex Freundlich

2010-11-29

III-V photovoltaics have exhibited efficiencies above 40%, but have found only a limited use because of the high cost of single crystal substrates. At the other end of the spectrum, polycrystalline and amorphous thin film solar cells offer the advantage of low-cost fabrication, but have not yielded high efficiencies. Our program is based on single-crystalline-like thin film photovoltaics on polycrystalline substrates using biaxially-textured templates made by Ion Beam-Assisted Deposition (IBAD). MgO templates made by IBAD on flexible metal substrate have been successfully used for epitaxial growth of germanium films. In spite of a 4.5% lattice mismatch, heteroepitaxial growth of Ge was achieved on CeO2 that was grown on IBAD MgO template. Room temperature optical bandgap of the Ge films was identified at 0.67 eV indicating minimal residual strain. Refraction index and extinction coefficient values of the Ge films were found to match well with that measured from a reference Ge single crystal. GaAs has been successfully grown epitaxially on Ge on metal substrate by molecular beam epitaxy. RHEED patterns indicate self annihilation of antiphase boundaries and the growth of a single domain GaAs. The GaAs is found to exhibit strong photoluminescence signal and, an existence of a relatively narrow (FWHM~20 meV) band-edge excitons measured in this film indicates a good optoelectronic quality of deposited GaAs. While excellent epitaxial growth has been achieved in GaAs on flexible metal substrates, the defect density of the films as measured by High Resolution X-ray Diffraction and etch pit experiments showed a high value of 5 * 10^8 per cm^2. Cross sectional transmission electron microscopy of the multilayer architecture showed concentration of threading dislocations near the germanium-ceria interface. The defect density was found decrease as the Ge films were made thicker. The defects appear to originate from the MgO layer presumably because of large lattice mismatches

Epitaxial growth of thin single-crystals and their quality study by Rutherford scattering in channeling conditions

International Nuclear Information System (INIS)

Kirsch, Robert.

1975-01-01

Some aspects of thin crystalline layers are reminded: vacuum deposition, epitaxial growth, annealing and interdiffusion ion channeling and scattering of 1-2MeV helium ions are used to study the crystalline quality, the annealing effects and in some cases the interdiffusion in epitaxial multilayers of silver, copper gold and nickel. Thin single-crystals of gold and nickel oriented (III) plan parallel to the surface were obtained by successive epitaxial growth from muscovite mica clivages. The mounting techniques of single crystalline, self-supporting, 300 to 1200 Angstroems thick, gold and nickel targets of 3mm diameter are described. The gold single-crystals have dislocation densities of 10 8 cm -2 and the various epitaxial layers are obtained without twinning [fr

Relationship between type III-V radio and hard X-ray bursts

International Nuclear Information System (INIS)

Stewart, R.T.

1978-01-01

Type III-V radio bursts are found to be closely associated with impulsive hard X-ray bursts. Probably 0.1% to 1% of the fast electrons in the X-ray source region escape to heights >0.1 solar radii in the corona and excite the type III-V burst. (Auth.)

Electrochemical synthesis of highly crystalline copper nanowires

International Nuclear Information System (INIS)

Kaur, Amandeep; Gupta, Tanish; Kumar, Akshay; Kumar, Sanjeev; Singh, Karamjeet; Thakur, Anup

2015-01-01

Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits

Investigation of optimal conditions for production of highly crystalline nanocellulose with increased yield via novel Cr(III)-catalyzed hydrolysis: Response surface methodology.

Science.gov (United States)

Chen, You Wei; Lee, Hwei Voon; Abd Hamid, Sharifah Bee

2017-12-15

For the first time, a highly efficient Cr(NO 3 ) 3 catalysis system was proposed for optimization the yield and crystallinity of nanocellulose end product. A five-level three-factor central composite design coupled with response surface methodology was employed to elucidate parameters interactions between three design factors, namely reaction temperature (x 1 ), reaction time (x 2 ) and concentration of Cr(NO 3 ) 3 (x 3 ) over a broad range of process conditions and determine the effect on crystallinity index and product yield. The developed models predicted the maximum nanocellulose yield of 87% at optimum process conditions of 70.6°C, 1.48h, and 0.48M Cr(NO 3 ) 3 . At these conditions, the obtained nanocellulose presented high crystallinity index (75.3%), spider-web-like interconnected network morphology with the average width of 31.2±14.3nm. In addition, the yielded nanocellulose rendered a higher thermal stability than that of original cellulosic source and expected to be widely used as reinforcement agent in bio-nanocomposites materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cacotheline as an oxidimetric reagent. Determination of Sn(II), Cu(I), Ti(III), Fe(II), V(II) and V(III)

International Nuclear Information System (INIS)

Nemani Murty, K.; Yedluri Rao, P.; Geddada Chalam, K.

1982-01-01

Sn(II), Ti(III), Cu(I),Fe(II), V(III) and V(II) can be titrated potentiometrically with cacotheline in 1-4 M hydrochloric acid, 0.5-2 M hydrochloric acid, 0.5-1.5 M sulphuric acid in presence of 4 ml of 10% EDTA solution in a total volume of 50 ml, 9-10 M phosphoric acid, 4-8 M acetic acid and 3-8 M acetic acid respectively. Cacotheline can be used for the assay of tin plate and solder. The cacotheline undergoes a 2-electron reduction reaction. A cacotheline solution (0.005 M) in 0.02 M hydrochloric acid is fairly stable for several months. The conditional redox potentials of cacotheline have been determined in sulphuric, phosphoric and acetic acid medium. (Author)

Final Report: Vapor Transport Deposition for Thin Film III-V Photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Boettcher, Shannon [Univ. of Oregon, Eugene, OR (United States); Greenaway, Ann [Univ. of Oregon, Eugene, OR (United States); Boucher, Jason [Univ. of Oregon, Eugene, OR (United States); Aloni, Shaul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2016-02-10

Silicon, the dominant photovoltaic (PV) technology, is reaching its fundamental performance limits as a single absorber/junction technology. Higher efficiency devices are needed to reduce cost further because the balance of systems account for about two-thirds of the overall cost of the solar electricity. III-V semiconductors such as GaAs are used to make the highest-efficiency photovoltaic devices, but the costs of manufacture are much too high for non-concentrated terrestrial applications. The cost of III-V’s is driven by two factors: (1) metal-organic chemical vapor deposition (MOCVD), the dominant growth technology, employs expensive, toxic and pyrophoric gas-phase precursors, and (2) the growth substrates conventionally required for high-performance devices are monocrystalline III-V wafers. The primary goal of this project was to show that close-spaced vapor transport (CSVT), using water vapor as a transport agent, is a scalable deposition technology for growing low-cost epitaxial III-V photovoltaic devices. The secondary goal was to integrate those devices on Si substrates for high-efficiency tandem applications using interface nanopatterning to address the lattice mismatch. In the first task, we developed a CSVT process that used only safe solid-source powder precursors to grow epitaxial GaAs with controlled n and p doping and mobilities/lifetimes similar to that obtainable via MOCVD. Using photoelectrochemical characterization, we showed that the best material had near unity internal quantum efficiency for carrier collection and minority carrier diffusions lengths in of ~ 8 μm, suitable for PV devices with >25% efficiency. In the second task we developed the first pn junction photovoltaics using CSVT and showed unpassivated structures with open circuit photovoltages > 915 mV and internal quantum efficiencies >0.9. We also characterized morphological and electrical defects and identified routes to reduce those defects. In task three we grew epitaxial

New insights into thorium and uranium oxo-arsenic (III/V) and oxo-phosphates (V) crystal chemistry

International Nuclear Information System (INIS)

Yu, Na

2015-01-01

The fundamental chemistry of actinides is of great interest owing to the diverse number of valence states and complex coordination chemistry of the actinides. The phases based on actinides and oxo-salt fragments have been under thorough investigation in the last decades. These compounds can be widely found in nature and they affect the migration process of actinides in nature. A better understanding of the fundamental coordination chemistry of actinide compounds with oxo-salts of group V elements is not only important for understanding the actinides behavior within the migration process but can also be used to understand actinide properties in phosphate ceramics. Concerning the radioactive issues, the less radioactive early actinides (i.e. U, Th) can be taken as modeling elements to study the crystal chemistry of the transuranic elements (Np, Pu) without the major handling problems. This can be done as Th(IV) has a very similar coordination chemistry with An(IV) and U(VI) can be chosen as a modeling element for transuranic elements in higher valence states. Therefore, a systematic research on the actinides (U, Th) bearing phases with tetrahedral oxo-anions such as phosphates and arsenates have been performed in this work. High temperature (HT) solid state reaction, High pressure high temperature (HP-HT) solid state reaction and the hydrothermal method were the methods of choice for synthesizing actinide bearing oxo-arsenic(III/V) and oxo- phosphorus(V) phases in the past three years. As a result, numerous novel compounds containing actinides were obtained. The structures of all compounds were determined using single crystal X-ray diffraction data. Raman spectroscopy, EDS, DSC and high temperature powder X-ray diffraction (HT-PXRD) measurements were implemented to characterize the chemical and physical properties of the obtained compounds. The core of this dissertation is a fundamental study of the crystal chemistry of actinides (Th, U) oxo-arsenic (III/V) and oxo-phosphate(V

Implications of the Differential Toxicological Effects of III-V Ionic and Particulate Materials for Hazard Assessment of Semiconductor Slurries.

Science.gov (United States)

Jiang, Wen; Lin, Sijie; Chang, Chong Hyun; Ji, Zhaoxia; Sun, Bingbing; Wang, Xiang; Li, Ruibin; Pon, Nanetta; Xia, Tian; Nel, André E

2015-12-22

Because of tunable band gaps, high carrier mobility, and low-energy consumption rates, III-V materials are attractive for use in semiconductor wafers. However, these wafers require chemical mechanical planarization (CMP) for polishing, which leads to the generation of large quantities of hazardous waste including particulate and ionic III-V debris. Although the toxic effects of micron-sized III-V materials have been studied in vivo, no comprehensive assessment has been undertaken to elucidate the hazardous effects of submicron particulates and released III-V ionic components. Since III-V materials may contribute disproportionately to the hazard of CMP slurries, we obtained GaP, InP, GaAs, and InAs as micron- (0.2-3 μm) and nanoscale (particles for comparative studies of their cytotoxic potential in macrophage (THP-1) and lung epithelial (BEAS-2B) cell lines. We found that nanosized III-V arsenides, including GaAs and InAs, could induce significantly more cytotoxicity over a 24-72 h observation period. In contrast, GaP and InP particulates of all sizes as well as ionic GaCl3 and InCl3 were substantially less hazardous. The principal mechanism of III-V arsenide nanoparticle toxicity is dissolution and shedding of toxic As(III) and, to a lesser extent, As(V) ions. GaAs dissolves in the cell culture medium as well as in acidifying intracellular compartments, while InAs dissolves (more slowly) inside cells. Chelation of released As by 2,3-dimercapto-1-propanesulfonic acid interfered in GaAs toxicity. Collectively, these results demonstrate that III-V arsenides, GaAs and InAs nanoparticles, contribute in a major way to the toxicity of III-V materials that could appear in slurries. This finding is of importance for considering how to deal with the hazard potential of CMP slurries.

Room temperature photoluminescence in crystalline/amorphous Er-doped Cd{sub 2}V{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Cid-Garcia, A. [Benemerita Universidad Autonoma de Puebla. Postgrado en Fisica Aplicada. Facultad de Ciencias Fisico-Matematicas, Mexico (Mexico); Lozada-Morales, R., E-mail: rlozada@fcfm.buap.mx [Benemerita Universidad Autonoma de Puebla. Postgrado en Fisica Aplicada. Facultad de Ciencias Fisico-Matematicas, Mexico (Mexico); Lopez-Calzada, G. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Apartado Postal 1-798, Queretaro, Qro. 76001 (Mexico); Zayas, Ma. E. [Departamento de Investigacion en Fisica de la Universidad de Sonora, Edificio 3I, Blvd. Edificio 5 E, Luis Encinas s/n, Col. Centro, 83000. Hermosillo, Sonora, Mexico (Mexico); Zelaya Angel, O. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados, P.O. Box 14-740, Mexico 07360 D. F. (Mexico); and others

2012-06-15

Er{sup 3+} ions were introduced into a new type of oxide matrixes prepared with different proportions of CdO and V{sub 2}O{sub 5}. The source of Er{sup 3+} employed was Er(NO{sub 3}){sub 3}{center_dot}5H{sub 2}O, which yielded an Er{sup 3+} concentration of {approx}1 at%. Depending on the reactants proportions, the samples resulted in crystalline or amorphous structures. X-ray diffraction indicated that the crystalline samples were constituted by polycrystalline Cd{sub 2}V{sub 2}O{sub 7}, in agreement with Raman spectroscopy measurements. Depending on the proportions of the component oxides, the band gap changed in the 2.49-1.77 eV energy range, as determined through photoacoustic spectroscopy. From photoluminescence spectra, the following electronic transitions of Er{sup 3+} were observed in both types of samples: {l_brace}{sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}{r_brace}{yields}{sup 4}I{sub 15/2} and {sup 4}S{sub 3/2}{yields}{sup 4}I{sub 13/2}. In the case of crystalline samples manifolds, originating from the Stark effect, were measured for the {l_brace}{sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, {sup 4}F{sub 9/2}{r_brace}{yields}{sup 4}I{sub 15/2} and {sup 4}S{sub 3/2}{yields}{sup 4}I{sub 13/2} transitions. - Highlights: Black-Right-Pointing-Pointer The Cd{sub 2}V{sub 2}O{sub 7} has been fabricated in amorphous and crystalline phases. Black-Right-Pointing-Pointer The band gap of crystalline samples varied in the 2.49-2.41 eV range. Black-Right-Pointing-Pointer The absorption edge for the glasses had lower values with a minimum of 1.77 eV. Black-Right-Pointing-Pointer The {l_brace}{sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}{r_brace}{yields}{sup 4}I{sub 15/2} and {sup 4}S{sub 3/2}{yields}{sup 4}I{sub 13/2,} were observed in PL.

Alpha-crystallin-type heat shock proteins: socializing minichaperones in the context of a multichaperone network.

Science.gov (United States)

Narberhaus, Franz

2002-03-01

Alpha-crystallins were originally recognized as proteins contributing to the transparency of the mammalian eye lens. Subsequently, they have been found in many, but not all, members of the Archaea, Bacteria, and Eucarya. Most members of the diverse alpha-crystallin family have four common structural and functional features: (i) a small monomeric molecular mass between 12 and 43 kDa; (ii) the formation of large oligomeric complexes; (iii) the presence of a moderately conserved central region, the so-called alpha-crystallin domain; and (iv) molecular chaperone activity. Since alpha-crystallins are induced by a temperature upshift in many organisms, they are often referred to as small heat shock proteins (sHsps) or, more accurately, alpha-Hsps. Alpha-crystallins are integrated into a highly flexible and synergistic multichaperone network evolved to secure protein quality control in the cell. Their chaperone activity is limited to the binding of unfolding intermediates in order to protect them from irreversible aggregation. Productive release and refolding of captured proteins into the native state requires close cooperation with other cellular chaperones. In addition, alpha-Hsps seem to play an important role in membrane stabilization. The review compiles information on the abundance, sequence conservation, regulation, structure, and function of alpha-Hsps with an emphasis on the microbial members of this chaperone family.

Cleavage mechanoluminescence in elemental and III-V semiconductors

International Nuclear Information System (INIS)

Chandra, B.P.; Patel, R.P.; Gour, Anubha S.; Chandra, V.K.; Gupta, R.K.

2003-01-01

The present paper reports the theory of mechanoluminescence (ML) produced during cleavage of elemental and III-V semiconductors. It seems that the formation of crack-induced localized states is responsible for the ML excitation produced during the cleavage of elemental and III-V semiconductors. According to this mechanism, as the atoms are drawn away from each other in an advancing crack tip, the decreasing wave function overlap across the crack may result in localized states which is associated with increasing electron energy. If the energy of these localized states approach that of the conduction band, transition to the conduction band via tunnelling would be possible, creating minority carriers, and consequently the electron-hole recombination may give rise to mechanoluminescence. When an elemental or III-V semiconductor is cleaved, initially the ML intensity increases with time, attains a peak value I m at the time t m corresponding to completion of the cleavage of the semiconductor, and then it decreases following power law decay. Expressions are derived for the ML intensity I m corresponding to the peak of the ML intensity versus time curve and for the total ML intensity I T . It is shown that both I m and I T should increase directly with the area of the newly created surfaces of the crystals. From the measurements of the ML intensity, the velocity of crack propagation in material can be determined by using the relation v=H/t m

Fabrication of the tetrathiafulvalene–2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane charge transfer complex with high crystallinity by eutectic melting method

Science.gov (United States)

Kim, Jueun; Kang, Youngjong; Lee, Jaejong

2018-06-01

We show that high crystallinity and charge transporting gain can be obtained in a noble donor–acceptor system (CT complex) composed of organic complex: tetrathiafulvalene–2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TTF–F4TCNQ). The complex is small-gap organic metallic or semiconductor (less than 1 eV), and we predict having a high conductivity. We perform an approach to fabricate organic CT complex with high crystallinity by eutectic melting method. Our process is simple and shows crystal growth with improved crystallinity when combined with soft-lithography.

Characterization of the crystalline quality of β-SiC formed by ion beam synthesis

International Nuclear Information System (INIS)

Intarasiri, S.; Hallen, A.; Kamwanna, T.; Yu, L.D.; Possnert, G.; Singkarat, S.

2006-01-01

The ion beam synthesis (IBS) technique is applied to form crystalline silicon carbide (SiC) for future optoelectronics applications. Carbon ions at 80 and 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at room temperature and 400 deg. C, respectively, to doses in excess of 10 17 ions/cm 2 . Subsequent thermal annealing of the implanted samples was performed in a vacuum furnace at temperatures of 800, 900 and 1000 deg. C, respectively. Elastic recoil detection analysis was used to investigate depth distributions of the implanted ions and infrared transmittance (IR) measurement was used to characterize formation of SiC in the implanted Si substrate. Complementary to IR, Raman scattering measurements were also carried out. Levels of the residual damage distribution of the samples annealed at different temperatures were compared with that of the as-implanted one by Rutherford backscattering spectrometry (RBS) in the channeling mode. The results show that C-ion implantation at the elevated temperature, followed by high-temperature annealing, enhances the synthesis of crystalline SiC

Silicon photonics fiber-to-the-home transceiver array based on transfer-printing-based integration of III-V photodetectors.

Science.gov (United States)

Zhang, Jing; De Groote, Andreas; Abbasi, Amin; Loi, Ruggero; O'Callaghan, James; Corbett, Brian; Trindade, António José; Bower, Christopher A; Roelkens, Gunther

2017-06-26

A 4-channel silicon photonics transceiver array for Point-to-Point (P2P) fiber-to-the-home (FTTH) optical networks at the central office (CO) side is demonstrated. A III-V O-band photodetector array was integrated onto the silicon photonic transmitter through transfer printing technology, showing a polarization-independent responsivity of 0.39 - 0.49 A/W in the O-band. The integrated PDs (30 × 40 μm 2 mesa) have a 3 dB bandwidth of 11.5 GHz at -3 V bias. Together with high-speed C-band silicon ring modulators whose bandwidth is up to 15 GHz, operation of the transceiver array at 10 Gbit/s is demonstrated. The use of transfer printing for the integration of the III-V photodetectors allows for an efficient use of III-V material and enables the scalable integration of III-V devices on silicon photonics wafers, thereby reducing their cost.

Atomic layer deposition of crystalline SrHfO{sub 3} directly on Ge (001) for high-k dielectric applications

Energy Technology Data Exchange (ETDEWEB)

McDaniel, Martin D.; Ngo, Thong Q.; Ekerdt, John G., E-mail: ekerdt@utexas.edu [Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Hu, Chengqing; Jiang, Aiting; Yu, Edward T. [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States); Lu, Sirong; Smith, David J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Posadas, Agham; Demkov, Alexander A. [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

2015-02-07

The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO{sub 3} (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10{sup −5} A/cm{sup 2} at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (D{sub it}) is estimated to be as low as ∼2 × 10{sup 12 }cm{sup −2 }eV{sup −1} under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased D{sub it} value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications.

III-V/Si wafer bonding using transparent, conductive oxide interlayers

Energy Technology Data Exchange (ETDEWEB)

Tamboli, Adele C., E-mail: Adele.Tamboli@nrel.gov; Hest, Maikel F. A. M. van; Steiner, Myles A.; Essig, Stephanie; Norman, Andrew G.; Bosco, Nick; Stradins, Paul [National Center for Photovoltaics, National Renewable Energy Laboratory, 15013 Denver West Pkwy, Golden, Colorado 80401 (United States); Perl, Emmett E. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106-9560 (United States)

2015-06-29

We present a method for low temperature plasma-activated direct wafer bonding of III-V materials to Si using a transparent, conductive indium zinc oxide interlayer. The transparent, conductive oxide (TCO) layer provides excellent optical transmission as well as electrical conduction, suggesting suitability for Si/III-V hybrid devices including Si-based tandem solar cells. For bonding temperatures ranging from 100 °C to 350 °C, Ohmic behavior is observed in the sample stacks, with specific contact resistivity below 1 Ω cm{sup 2} for samples bonded at 200 °C. Optical absorption measurements show minimal parasitic light absorption, which is limited by the III-V interlayers necessary for Ohmic contact formation to TCOs. These results are promising for Ga{sub 0.5}In{sub 0.5}P/Si tandem solar cells operating at 1 sun or low concentration conditions.

Enhancing the piezoelectric properties of flexible hybrid AlN materials using semi-crystalline parylene

Science.gov (United States)

Jackson, Nathan; Mathewson, Alan

2017-04-01

Flexible piezoelectric materials are desired for numerous applications including biomedical, wearable, and flexible electronics. However, most flexible piezoelectric materials are not compatible with CMOS fabrication technology, which is desired for most MEMS applications. This paper reports on the development of a hybrid flexible piezoelectric material consisting of aluminium nitride (AlN) and a semi-crystalline polymer substrate. Various types of semi-crystalline parylene and polyimide materials were investigated as the polymer substrate. The crystallinity and surfaces of the polymer substrates were modified by micro-roughening and annealing in order to determine the effects on the AlN quality. The AlN crystallinity and piezoelectric properties decreased when the polymer surfaces were treated with O2 plasma. However, increasing the crystallinity of the parylene substrate prior to deposition of AlN caused enhanced c-axis (002) AlN crystallinity and piezoelectric response of the AlN. Piezoelectric properties of 200 °C annealed parylene-N substrate resulted in an AlN d 33 value of 4.87 pm V-1 compared to 2.17 pm V-1 for AlN on polyimide and 4.0 pm V-1 for unannealed AlN/parylene-N. The electrical response measurements to an applied force demonstrated that the parylene/AlN hybrid material had higher V pp (0.918 V) than commercial flexible piezoelectric material (PVDF) (V pp 0.36 V). The results in this paper demonstrate that the piezoelectric properties of a flexible AlN hybrid material can be enhanced by increasing the crystallinity of the polymer substrate, and the enhanced properties can function better than previous flexible piezoelectrics.

Fabrication of high crystalline SnS and SnS2 thin films, and their switching device characteristics

Science.gov (United States)

Choi, Hyeongsu; Lee, Jeongsu; Shin, Seokyoon; Lee, Juhyun; Lee, Seungjin; Park, Hyunwoo; Kwon, Sejin; Lee, Namgue; Bang, Minwook; Lee, Seung-Beck; Jeon, Hyeongtag

2018-05-01

Representative tin sulfide compounds, tin monosulfide (SnS) and tin disulfide (SnS2) are strong candidates for future nanoelectronic devices, based on non-toxicity, low cost, unique structures and optoelectronic properties. However, it is insufficient for synthesizing of tin sulfide thin films using vapor phase deposition method which is capable of fabricating reproducible device and securing high quality films, and their device characteristics. In this study, we obtained highly crystalline SnS thin films by atomic layer deposition and obtained highly crystalline SnS2 thin films by phase transition of the SnS thin films. The SnS thin film was transformed into SnS2 thin film by annealing at 450 °C for 1 h in H2S atmosphere. This phase transition was confirmed by x-ray diffractometer and x-ray photoelectron spectroscopy, and we studied the cause of the phase transition. We then compared the film characteristics of these two tin sulfide thin films and their switching device characteristics. SnS and SnS2 thin films had optical bandgaps of 1.35 and 2.70 eV, and absorption coefficients of about 105 and 104 cm‑1 in the visible region, respectively. In addition, SnS and SnS2 thin films exhibited p-type and n-type semiconductor characteristics. In the images of high resolution-transmission electron microscopy, SnS and SnS2 directly showed a highly crystalline orthorhombic and hexagonal layered structure. The field effect transistors of SnS and SnS2 thin films exhibited on–off drain current ratios of 8.8 and 2.1 × 103 and mobilities of 0.21 and 0.014 cm2 V‑1 s‑1, respectively. This difference in switching device characteristics mainly depends on the carrier concentration because it contributes to off-state conductance and mobility. The major carrier concentrations of the SnS and SnS2 thin films were 6.0 × 1016 and 8.7 × 1013 cm‑3, respectively, in this experiment.

Influence of V/III growth flux ratio on trap states in m-plane GaN grown by ammonia-based molecular beam epitaxy

International Nuclear Information System (INIS)

Zhang, Z.; Arehart, A. R.; Hurni, C. A.; Speck, J. S.; Ringel, S. A.

2012-01-01

Deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) were utilized to investigate the behavior of deep states in m-plane, n-type GaN grown by ammonia-based molecular beam epitaxy (NH 3 -MBE) as a function of systematically varied V/III growth flux ratios. Levels were detected at E C - 0.14 eV, E C - 0.21 eV, E C - 0.26 eV, E C - 0.62 eV, E C - 0.67 eV, E C - 2.65 eV, and E C - 3.31 eV, with the concentrations of several traps exhibiting systematic dependencies on V/III ratio. The DLTS spectra are dominated by traps at E C - 0.14 eV and E C - 0.67 eV, whose concentrations decreased monotonically with increasing V/III ratio and decreasing oxygen impurity concentration, and by a trap at E C - 0.21 eV that revealed no dependence of its concentration on growth conditions, suggestive of different physical origins. Higher concentrations of deeper trap states detected by DLOS with activation energies of E C - 2.65 eV and E C - 3.31 eV in each sample did not display measureable sensitivity to the intentionally varied V/III ratio, necessitating further study on reducing these deep traps through growth optimization for maximizing material quality of NH 3 -MBE grown m-plane GaN.

Removal of Sb(III and Sb(V by Ferric Chloride Coagulation: Implications of Fe Solubility

Directory of Open Access Journals (Sweden)

Muhammad Ali Inam

2018-04-01

Full Text Available Coagulation and precipitation appear to be the most efficient and economical methods for the removal of antimony from aqueous solution. In this study, antimony removal from synthetic water and Fe solubility with ferric chloride (FC coagulation has been investigated. The effects of pH, FC dosage, initial antimony loading and mixed Sb(III, Sb(V proportions on Fe solubility and antimony removal were studied. The results showed that the Sb(III removal efficiency increased with the increase of solution pH particularly due to an increase in Fe precipitation. The Sb(V removal was influenced by the solution pH due to a change in Fe solubility. However, the Fe solubility was only impaired by the Sb(III species at optimum pH 7. The removal efficiencies of both Sb species were enhanced with an increase in FC dose. The quantitative analysis of the isotherm study revealed the strong adsorption potential of Sb(III on Fe precipitates as compared to Sb(V. Furthermore, the removal behavior of antimony was inhibited in mixed proportion with high Sb(V fraction. In conclusion, this study contributes to better understanding the fate of Sb species, their mobilities, and comparative removal behavior, with implications for Fe solubility using ferric chloride in different aqueous environments.

Thermal oxidation of III-V compounds

International Nuclear Information System (INIS)

Monteiro, O.R.; Evans, J.W.

1988-01-01

The thermal oxidation of two important III-V compound semiconductor materials, namely GaAs and InP, has been studied between 300 and 600 0 C. In-situ TEM, cross-sectional TEM (XTEM) and SIMS analyses were used to characterize the reaction products. The first technique allows us to access the reactions at the very moment they are occurring. XTEM provides a clearer picture of the distribution of phases in the oxidized samples. SIMS gives us information on the dopant redistribution after oxidation as well as enrichment of group V element at the oxide semiconductor interface. Based on those results, the reaction products were characterized and reaction mechanisms proposed

Development of highly porous crystalline titania photocatalysts

Science.gov (United States)

Marszewski, Michal

The objectives of this dissertation are the design, synthesis, and characterization of titania materials with surface area, porosity, crystallinity and doping tailored toward photocatalytic applications. Ultimately, the research should result in a strategy allowing the synthesis of titania with all these important features. The synthetic methods investigated in this research will include: i) soft-templating, ii) hard-templating, and iii) modified precursor strategy. Soft-templating strategy uses organic templates--either block copolymers or surfactants--that under specific conditions assemble into micelles, and later, these micelles are used to template the desired material around them. The resulting organic-inorganic composite is then calcined in air to remove the organic template and recover the final material with high surface area and large pore volume. This work explores 1) synthesis of titania materials in the presence of polymer templates, and the effects of different synthetic conditions on the structure of the resulting materials. Hard-templating, in contrast to soft-templating, uses inorganic templates. The hard template is introduced during the synthesis to cast its shape onto the fabricated material and removed afterwards, when the material has formed. The final material is an inverse replica of the hard template used, typically with a well-developed mesostructure. This work explores 1) hard templating synthesis of titania materials using silica and alumina, and 2) the effects of the template amount and type. The modified precursor strategy is a novel synthetic method, developed in this research, and designed specifically to achieve titania material with high surface area, large pore volume, high crystallinity, and possibly doping. The modified precursors are prepared by reacting generic titania precursors, such as titanium isopropoxide (TIPO), with organic acids, which results in substitution of some or all alkoxide groups in TIPO structure. The goal

Compounds of type Ba/sub 2/Bsup(III)Ossup(V)O/sub 6/

Energy Technology Data Exchange (ETDEWEB)

Treiber, U; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1981-07-01

The black perovskites of type Ba/sub 2/Bsup(III)Ossup(V)O/sub 6/ crystallize cubic (Bsup(III) = Pr, Nd, Sm-Lu, Y) and rhombohedral (Bsup(III) = La) respectively; the cell volumina decrease linearily with (rsub(B)sup(III))/sup 3/. Intensity calculations on powder data for Ba/sub 2/YOsO/sub 6/ (space group Fm3m-Osub(h)/sup 5/) and Ba/sub 2/LaOsO/sub 6/ (space group R-3m-Dsub(3d)/sup 5/) gave the intensity related R'values of 4.6% and 5.0% respectively. The results of the vibrational spectroscopic investigations are reported in common with the bond orders, M-O distances and mean amplitudes and compared with the corresponding values of the series Ba/sub 2/Bsup(III)Irsup(V)O/sub 6/ and Ba/sub 2/Bsup(III)Rusup(V)O/sub 6/.

High Resolution Air Quality Forecasts in the Western Mediterranean area within the MACC, MACC-II and MACC-III European projects

Energy Technology Data Exchange (ETDEWEB)

Cansado, A.; Martinez, I.; Morales, T.

2015-07-01

The European Earth observation programme Copernicus, formerly known as GMES (Global Monitoring for Environment and Security) is establishing a core global and regional environmental atmospheric service as a component of the Europes Copernicus/GMES initiative through successive R and D projects led by ECMWF (European Center for Medium-range Weather Forecasting) and funded by the 6th and 7th European Framework Programme for Research and Horizon 2020 Programme: GEMS, MACC, MACC-II and MACC-III. AEMET (Spanish State Meteorological Agency) has participated in the projects MACC and MACC-II and continues participating in MACC-III (http://atmosphere.copernicus.eu). AEMET has contributed to those projects by generating highresolution (0.05 degrees) daily air-quality forecasts for the Western Mediterranean up to 48 hours aiming to analyse the dependence of the quality of forecasts on resolution. We monitor the evolution of different chemical species such as NO{sub 2}, O{sub 3}, CO y SO{sub 2} at surface and different vertical levels using the global model MOCAGE and the MACC Regional Ensemble forecasts as chemical boundary conditions. We will show different case-studies, where the considered chemical species present high values and will show a validation of the air-quality by comparing to some of the available air-quality observations (EMEP/GAW, regional -autonomous communities- and local -city councils- air-quality monitoring networks) over the forecast domain. The aim of our participation in these projects is helping to improve the understanding of the processes involved in the air-quality forecast in the Mediterranean where special factors such as highly populated areas together with an intense solar radiation make air-quality forecasting particularly challenging. (Author)

High Resolution Air Quality Forecasts in the Western Mediterranean area within the MACC, MACC-II and MACC-III European projects

Energy Technology Data Exchange (ETDEWEB)

Cansado, A.; Martinez, I.; Morales, T.

2015-07-01

The European Earth observation programme Copernicus, formerly known as GMES (Global Monitoring for Environment and Security) is establishing a core global and regional environmental atmospheric service as a component of the Europe’s Copernicus/GMES initiative through successive R&D projects led by ECMWF (European Center for Medium-range Weather Forecasting) and funded by the 6th and 7th European Framework Programme for Research and Horizon 2020 Programme: GEMS, MACC, MACC-II and MACC-III. AEMET (Spanish State Meteorological Agency) has participated in the projects MACC and MACC-II and continues participating in MACC-III (http://atmosphere.copernicus.eu). AEMET has contributed to those projects by generating highresolution (0.05 degrees) daily air-quality forecasts for the Western Mediterranean up to 48 hours aiming to analyse the dependence of the quality of forecasts on resolution. We monitor the evolution of different chemical species such as NO2, O3, CO y SO2 at surface and different vertical levels using the global model MOCAGE and the MACC Regional Ensemble forecasts as chemical boundary conditions. We will show different case-studies, where the considered chemical species present high values and will show a validation of the air-quality by comparing to some of the available air-quality observations (EMEP/GAW, regional -autonomous communities- and local -city councils- air-quality monitoring networks) over the forecast domain. The aim of our participation in these projects is helping to improve the understanding of the processes involved in the air-quality forecast in the Mediterranean where special factors such as highly populated areas together with an intense solar radiation make air-quality forecasting particularly challenging. (Author)

Bismuth containing III-V quaternary alloy InGaAsBi grown by MBE

International Nuclear Information System (INIS)

Feng, G.; Oe, K.; Yoshimoto, M.

2006-01-01

InGaAsBi epilayers were created on InP substrates by molecular beam epitaxy for the first time. The high crystalline quality of the InGaAsBi epilayer with smooth interface was confirmed by high resolution X-ray diffraction measurements. Up to 2.5% Bi was incorporated in the film based on Rutherford back scattering (RBS) results. The RBS channeling spectra give clear evidence that the Bi atoms were substitutionally located in the InGaAs zinc-blende lattice sites. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Interpreting Interfacial Structure in Cross-Sectional STM Images of III-V Semiconductor Heterostructures

National Research Council Canada - National Science Library

Nosho, B. Z; Barvosa-Carter, W; Yang, M. J; Bennett, B. R; Whitman, L. J

2000-01-01

...) can be used for the study of III-V heterostructure interfaces. The interpretation of interfacial structure in XSTM images is impeded by the fact that only every other III or V plane as grown on the (001...

Rapid arsenic(V)-reduction by fire in schwertmannite-rich soil enhances arsenic mobilisation

Science.gov (United States)

Johnston, Scott G.; Bennett, William W.; Burton, Edward D.; Hockmann, Kerstin; Dawson, Nigel; Karimian, Niloofar

2018-04-01

Arsenic in acid sulfate soil (ASS) landscapes commonly associates with schwertmannite, a poorly crystalline Fe(III) mineral. Fires in ASS landscapes can thermally transform Fe(III) minerals to more crystalline phases, such as maghemite (γFe2O3). Although thermal genesis of maghemite requires electron transfer via organic matter pyrolysis, the possibility of fire causing concurrent transfer of electrons to schwertmannite-bound As(V) remains unexplored. Here, we subject an organic-rich soil with variable carbon content (∼9-44% organic C) mixed (4:1) with As(V)-bearing schwertmannite (total As of 4.7-5.4 μmol g-1), to various temperatures (200-800 °C) and heating durations (5-120 min). We explore the consequences for As and Fe via X-ray absorption spectroscopy, X-ray diffraction, 57Fe Mössbauer spectroscopy and selective extracts. Heating transforms schwertmannite to mainly maghemite and hematite at temperatures above 300-400 °C, with some transitory formation of magnetite, and electrons are readily transferred to both Fe(III) and As(V). As(V) reduction to As(III) is influenced by a combination of temperature, heating duration and carbon content and is significantly (P moderate fires in ASS landscapes, even of short duration, may generate considerable labile As(III) species and cause a pulse of As(III)aq mobilisation following initial re-wetting. Further research is warranted to examine if analogous As(III) formation occurs during combustion of organic-rich soil containing common As-bearing Fe(III) minerals such as ferrihydrite and goethite.

Preservation of water samples for arsenic(III/V) determinations: An evaluation of the literature and new analytical results

Science.gov (United States)

McCleskey, R. Blaine; Nordstrom, D. Kirk; Maest, A.S.

2004-01-01

Published literature on preservation procedures for stabilizing aqueous inorganic As(III/V) redox species contains discrepancies. This study critically evaluates published reports on As redox preservation and explains discrepancies in the literature. Synthetic laboratory preservation experiments and time stability experiments were conducted for natural water samples from several field sites. Any field collection procedure that filters out microorganisms, adds a reagent that prevents dissolved Fe and Mn oxidation and precipitation, and isolates the sample from solar radiation will preserve the As(III/V) ratio. Reagents that prevent Fe and Mn oxidation and precipitation include HCl, H 2SO4, and EDTA, although extremely high concentrations of EDTA are necessary for some water samples high in Fe. Photo-catalyzed Fe(III) reduction causes As(III) oxidation; however, storing the sample in the dark prevents photochemical reactions. Furthermore, the presence of Fe(II) or SO 4 inhibits the oxidation of As(III) by Fe(III) because of complexation reactions and competing reactions with free radicals. Consequently, fast abiotic As(III) oxidation reactions observed in the laboratory are not observed in natural water samples for one or more of the following reasons: (1) the As redox species have already stabilized, (2) most natural waters contain very low dissolved Fe(III) concentrations, (3) the As(III) oxidation caused by Fe(III) photoreduction is inhibited by Fe(II) or SO4.

Preservation of water samples for arsenic(III/V) determinations: an evaluation of the literature and new analytical results

International Nuclear Information System (INIS)

McCleskey, R.Blaine; Nordstrom, D.Kirk; Maest, Ann S.

2004-01-01

Published literature on preservation procedures for stabilizing aqueous inorganic As(III/V) redox species contains discrepancies. This study critically evaluates published reports on As redox preservation and explains discrepancies in the literature. Synthetic laboratory preservation experiments and time stability experiments were conducted for natural water samples from several field sites. Any field collection procedure that filters out microorganisms, adds a reagent that prevents dissolved Fe and Mn oxidation and precipitation, and isolates the sample from solar radiation will preserve the As(III/V) ratio. Reagents that prevent Fe and Mn oxidation and precipitation include HCl, H 2 SO 4 , and EDTA, although extremely high concentrations of EDTA are necessary for some water samples high in Fe. Photo-catalyzed Fe(III) reduction causes As(III) oxidation; however, storing the sample in the dark prevents photochemical reactions. Furthermore, the presence of Fe(II) or SO 4 inhibits the oxidation of As(III) by Fe(III) because of complexation reactions and competing reactions with free radicals. Consequently, fast abiotic As(III) oxidation reactions observed in the laboratory are not observed in natural water samples for one or more of the following reasons: (1) the As redox species have already stabilized, (2) most natural waters contain very low dissolved Fe(III) concentrations, (3) the As(III) oxidation caused by Fe(III) photoreduction is inhibited by Fe(II) or SO 4

Titanium nitride as an electrocatalyst for V(II)/V(III) redox couples in all-vanadium redox flow batteries

International Nuclear Information System (INIS)

Yang, Chunmei; Wang, Haining; Lu, Shanfu; Wu, Chunxiao; Liu, Yiyang; Tan, Qinglong; Liang, Dawei; Xiang, Yan

2015-01-01

Titanium nitride nanoparticles (TiN NPs) are proposed as a novel catalyst towards the V(II)/V(III) redox pair for the negative electrode in vanadium redox flow batteries (VRFB). Electrochemical properties of TiN NPs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that TiN NPs demonstrate better electrochemical activity and reversibility for the processes of V(II)/V(III) redox couples as compared with the graphite NPs. TiN NPs facilitate the charge transfer in the V(II)/V(III) redox reaction. Performance of a VRFB using a TiN NPs coated carbon paper as a negative electrode is much higher than that of a VRFB with a raw carbon paper electrode. The columbic efficiency (CE), the voltage efficiency (VE) and the energy efficiency (EE) of the VRFB single cell at charge-discharge current density of 30 mA/cm 2 are 91.74%, 89.11% and 81.74%, respectively. During a 50 charge-discharge cycles test, the CE values of VRFB with TiN NPs consistently remain higher than 90%.

Influence of substrate dc bias on crystallinity of silicon films grown at a high rate from inductively-coupled plasma CVD

International Nuclear Information System (INIS)

Kosku, N.; Murakami, H.; Higashi, S.; Miyazaki, S.

2005-01-01

We have investigated the effect of substrate bias on the microcrystalline film growth from inductively-coupled plasma (ICP) of H 2 -diluted SiH 4 at 250 deg. C to get an insight on the role of ion and electron incidence for the crystallization. By applying dc bias voltage to the substrate in the range of -20 ∼ 20 V during the film growth, the crystallinity is improved significantly with no significant change in the deposition rate, but in contrast the application of biases as high as ±50 V degrades the crystallinity. These results indicate that the incidence of ions or electrons with a moderate energy to the growing film surface promotes the nucleation and the growth of crystallites. Also, the optimum bias condition for the crystallization is changed with the antenna-substrate distance, which suggests the contribution of hydrogen radical flux to the crystalline film growth

Liquid crystalline epoxy nanocomposite material for dental application.

Science.gov (United States)

Tai, Yun-Yuan; Hsu, Sheng-Hao; Chen, Rung-Shu; Su, Wei-Fang; Chen, Min-Huey

2015-01-01

Novel liquid crystalline epoxy nanocomposites, which exhibit reduced polymerization shrinkage and effectively bond to tooth structures, can be applied in esthetic dentistry, including core and post systems, direct and indirect restorations, and dental brackets. The purposes of this study were to investigate the properties of liquid crystalline epoxy nanocomposites including biocompatibility, microhardness, and frictional forces of bracket-like blocks with different filler contents for further clinical applications. In this study, we evaluated liquid crystalline epoxy nanocomposite materials that exhibited various filler contents, by assessing their cell activity performance using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and their microhardness with or without thermocycling. We also evaluated the frictional force between bracket-like duplicates and commercially available esthetic bracket systems using Instron 5566. The liquid crystalline epoxy nanocomposite materials showed good biocompatibility. The materials having high filler content demonstrated greater microhardness compared with commercially available bracket materials, before and after the thermocycling treatment. Thus, manufacturing processes are important to reduce frictional force experienced by orthodontic brackets. The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment. Copyright © 2014. Published by Elsevier B.V.

New insights into thorium and uranium oxo-arsenic (III/V) and oxo-phosphates (V) crystal chemistry

Energy Technology Data Exchange (ETDEWEB)

Yu, Na

2015-12-11

The fundamental chemistry of actinides is of great interest owing to the diverse number of valence states and complex coordination chemistry of the actinides. The phases based on actinides and oxo-salt fragments have been under thorough investigation in the last decades. These compounds can be widely found in nature and they affect the migration process of actinides in nature. A better understanding of the fundamental coordination chemistry of actinide compounds with oxo-salts of group V elements is not only important for understanding the actinides behavior within the migration process but can also be used to understand actinide properties in phosphate ceramics. Concerning the radioactive issues, the less radioactive early actinides (i.e. U, Th) can be taken as modeling elements to study the crystal chemistry of the transuranic elements (Np, Pu) without the major handling problems. This can be done as Th(IV) has a very similar coordination chemistry with An(IV) and U(VI) can be chosen as a modeling element for transuranic elements in higher valence states. Therefore, a systematic research on the actinides (U, Th) bearing phases with tetrahedral oxo-anions such as phosphates and arsenates have been performed in this work. High temperature (HT) solid state reaction, High pressure high temperature (HP-HT) solid state reaction and the hydrothermal method were the methods of choice for synthesizing actinide bearing oxo-arsenic(III/V) and oxo- phosphorus(V) phases in the past three years. As a result, numerous novel compounds containing actinides were obtained. The structures of all compounds were determined using single crystal X-ray diffraction data. Raman spectroscopy, EDS, DSC and high temperature powder X-ray diffraction (HT-PXRD) measurements were implemented to characterize the chemical and physical properties of the obtained compounds. The core of this dissertation is a fundamental study of the crystal chemistry of actinides (Th, U) oxo-arsenic (III/V) and oxo-phosphate(V

neutron transmission through crystalline materials

International Nuclear Information System (INIS)

El Mesiry, M.S.

2011-01-01

The aim of the present work is to study the neutron transmission through crystalline materials. Therefore a study of pyrolytic graphite (PG) as a highly efficient selective thermal neutron filter and Iron single crystal as a whole one, as well as the applicability of using their polycrystalline powders as a selective cold neutron filters is given. Moreover, the use of PG and iron single crystal as an efficient neutron monochromator is also investigated. An additive formula is given which allows calculating the contribution of the total neutron cross-section including the Bragg scattering from different )(hkl planes to the neutron transmission through crystalline iron and graphite. The formula takes into account their crystalline form. A computer CFe program was developed in order to provide the required calculations for both poly- and single-crystalline iron. The validity of the CFe program was approved from the comparison of the calculated iron cross-section data with the available experimental ones. The CFe program was also adapted to calculate the reflectivity from iron single crystal when it used as a neutron monochromator The computer package GRAPHITE, developed in Neutron Physics laboratory, Nuclear Research Center, has been used in order to provide the required calculations for crystalline graphite in the neutron energy range from 0.1 meV to 10 eV. A Mono-PG code was added to the computer package GRAPHITE in order to calculate the reflectivity from PG crystal when it used as a neutron monochromator.

Thorium coprecipitation method for spectrophotometric determination of arsenic (III) and arsenic (V) in groundwaters

International Nuclear Information System (INIS)

Tamari, Yuzo; Yamamoto, Nobuki; Tsuji, Haruo; Kusaka, Yuzuru

1989-01-01

A new coprecipitation method for the spectrophotometry of arsenic (III) and arsenic (V) in groundwater has been developed. Arsenic (III) and arsenic (V) were coprecipitated with thorium (IV) hydroxide from 1000ml of groundwater at pH9. The precipitate was centrifuged and then dissolved with hydrochloric acid. Arsenic (III) was spectrophotometrically determined by the usual silver diethylditiocarbamate (Ag-DDTC) method after generating the arsenic to arsine with sodium tetrahydroborate under masking the thorium with EDTA-NaF at pH6. From another portion of the same groundwater, both arsenic (III) and arsenic (V) were determined by the Ag-DDTC method after reducing all the arsenic to arsine with sodium tetrahydroborate at pH less than 1 in the presence of the EDTA-NaF. The concentration of arsenic (V) was obtained by subtracting that of arsenic (III) from the total for arsenic. (author)

Observation of electron polarization above 80% in photoemission from strained III-V compounds

International Nuclear Information System (INIS)

Garwin, E.L.; Maruyama, T.; Prepost, R.; Zapalac, G.H.

1992-02-01

Spin-polarized electron photoemission has been investigated for strained III--V compounds; (1) strained In x Ga 1-x As epitaxially grown on a GaAs substrate, and (2) strained GaAs grown on a GaAs 1-x P x buffer layer. The lattice mismatched heterostructure results in a highly strained epitaxial layer, and electron spin polarization as high as 90% has been observed

Exploration of GaInTlP and related Tl-containing III-V alloys for photovoltaics

International Nuclear Information System (INIS)

Friedman, D. J.; Kurtz, Sarah R.; Kibbler, A. E.

1999-01-01

This paper discusses the results of an attempt to grow GaInTlP for application as a 1-eV material for the third junction of a GaInP/GaAs/3rd-junction high-efficiency solar cell. Although early indications from the literature were promising, we are unable to produce crystalline homogeneous material, and so we conclude that this material is not a promising candidate for such applications as photovoltaics

Cycloadditions to Epoxides Catalyzed by GroupIII-V Transition-Metal Complexes

KAUST Repository

D'Elia, Valerio

2015-05-25

Complexes of groupIII-V transition metals are gaining increasing importance as Lewis acid catalysts for the cycloaddition of dipolarophiles to epoxides. This review examines the latest reports, including homogeneous and heterogeneous applications. The pivotal step for the cycloaddition reactions is the ring opening of the epoxide following activation by the Lewis acid. Two modes of cleavage (C-C versus C-O) have been identified depending primarily on the substitution pattern of the epoxide, with lesser influence observed from the Lewis acid employed. The widely studied cycloaddition of CO2 to epoxides to afford cyclic carbonates (C-O bond cleavage) has been scrutinized in terms of catalytic efficiency and reaction mechanism, showing that unsophisticated complexes of groupIII-V transition metals are excellent molecular catalysts. These metals have been incorporated, as well, in highly performing, recyclable heterogeneous catalysts. Cycloadditions to epoxides with other dipolarophiles (alkynes, imines, indoles) have been conducted with scandium triflate with remarkable performances (C-C bond cleavage). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cycloadditions to Epoxides Catalyzed by GroupIII-V Transition-Metal Complexes

KAUST Repository

D'Elia, Valerio; Pelletier, Jeremie; Basset, Jean-Marie

2015-01-01

Complexes of groupIII-V transition metals are gaining increasing importance as Lewis acid catalysts for the cycloaddition of dipolarophiles to epoxides. This review examines the latest reports, including homogeneous and heterogeneous applications. The pivotal step for the cycloaddition reactions is the ring opening of the epoxide following activation by the Lewis acid. Two modes of cleavage (C-C versus C-O) have been identified depending primarily on the substitution pattern of the epoxide, with lesser influence observed from the Lewis acid employed. The widely studied cycloaddition of CO2 to epoxides to afford cyclic carbonates (C-O bond cleavage) has been scrutinized in terms of catalytic efficiency and reaction mechanism, showing that unsophisticated complexes of groupIII-V transition metals are excellent molecular catalysts. These metals have been incorporated, as well, in highly performing, recyclable heterogeneous catalysts. Cycloadditions to epoxides with other dipolarophiles (alkynes, imines, indoles) have been conducted with scandium triflate with remarkable performances (C-C bond cleavage). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Blocking of indium incorporation by antimony in III-V-Sb nanostructures

International Nuclear Information System (INIS)

Sanchez, A M; Beltran, A M; Ben, T; Molina, S I; Beanland, R; Gass, M H; De la Pena, F; Walls, M; Taboada, A G; Ripalda, J M

2010-01-01

The addition of antimony to III-V nanostructures is expected to give greater freedom in bandgap engineering for device applications. One of the main challenges to overcome is the effect of indium and antimony surface segregation. Using several very high resolution analysis techniques we clearly demonstrate blocking of indium incorporation by antimony. Furthermore, indium incorporation resumes when the antimony concentration drops below a critical level. This leads to major differences between nominal and actual structures.

A Thermodynamic Model for Acetate and Lactate Complexation with Am(III), Th(IV), Np(V)and U(V I) Valid to High Ionic Strength

International Nuclear Information System (INIS)

Moore, C.R.; Free, S.J.; Bynum, R.V.

1999-01-01

The organic ligands acetate, lactate, oxalate and EDTA have been identified as components of wastes targeted for disposal in the Waste Isolation Pilot Plant (WIPP) located in Southeastern New Mexico. The presence of these ligands may increase dissolved actinide concentrations and impact chemical radiation during transport. The current work considers the complexation of Am(III), Th (IV) , Np(V), and U(V I) with two of the organic ligands, acetate and lactate, in Na CI media from dilute through high concentration. A thermodynamic model for actinide complexation with the organic ligands has been developed based on the Pitzer activity coefficient formalism and the Harvie-Moller-Weare, Felmy-Weare database for describing brine evaporites systems. The model was parameterized using first apparent stability constant data from the literature. Because of complexation of other metal ions (Fe, Mg, Ni, Pb, etc.) present in the WIPP disposal room with the organic ligands, preliminary results from model calculations indicate the organic ligands do not significantly increase dissolved actinide concentrations

Long-wavelength III-V/silicon photonic integrated circuits

NARCIS (Netherlands)

Roelkens, G.C.; Kuyken, B.; Leo, F.; Hattasan, N.; Ryckeboer, E.M.P.; Muneeb, M.; Hu, C.L.; Malik, A.; Hens, Z.; Baets, R.G.F.; Shimura, Y.; Gencarelli, F.; Vincent, B.; Loo, van de R.; Verheyen, P.A.; Lepage, G.; Campenhout, van J.; Cerutti, L.; Rodriquez, J.B.; Tournie, E.; Chen, X; Nedeljkovic, G.; Mashanovich, G.; Liu, X.; Green, W.S.

2013-01-01

We review our work in the field of short-wave infrared and mid-infrared photonic integrated circuits for applications in spectroscopic sensing systems. Passive silicon waveguide circuits, GeSn photodetectors, the integration of III-V and IV-VI semiconductors on these circuits, and silicon nonlinear

Quality of life in patients with different constipation subtypes based on the Rome III criteria

OpenAIRE

M.C. Ruiz-López; E. Coss-Adame

2015-01-01

Background: Functional constipation and irritable bowel syndrome with constipation are highly prevalent and affect the quality of life of those who suffer from them. Aims: To evaluate quality of life in patients with functional constipation and irritable bowel disease in accordance with the Rome III criteria, using the PAC-QOL and SF-36 questionnaires. Materials and methods: A cross-sectional study was conducted using self-administered questionnaires. The PAC-QOL, SF-36, and Rome III co...

Subsurface dimerization in III-V semiconductor (001) surfaces

DEFF Research Database (Denmark)

Kumpf, C.; Marks, L.D.; Ellis, D.

2001-01-01

We present the atomic structure of the c(8 X 2) reconstructions of InSb-, InAs-, and GaAs-(001) surfaces as determined by surface x-ray diffraction using direct methods. Contrary to common belief, group III dimers are not prominent on the surface, instead subsurface dimerization of group m atoms ...... takes place in the second bilayer, accompanied by a major rearrangement of the surface atoms above the dimers to form linear arrays. By varying the occupancies of four surface sites the (001)-c(8 X 2) reconstructions of III-V semiconductors can be described in a unified model....

30 CFR 57.22202 - Main fans (I-A, I-B, I-C, II-A, III, V-A, and V-B mines).

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Main fans (I-A, I-B, I-C, II-A, III, V-A, and V... Main fans (I-A, I-B, I-C, II-A, III, V-A, and V-B mines). (a) Main fans shall be— (1) Installed on the... mines, provided with an automatic signal device to give an alarm when the fan stops. The signal device...

Cr-doped III-V nitrides: Potential candidates for spintronics

KAUST Repository

Amin, Bin

2011-02-19

Studies of Cr-doped III-V nitrides, dilute magnetic alloys in the zincblende crystal structure, are presented. The objective of the work is to investigate half-metallicity in Al 0.75Cr 0.25N, Ga 0.75Cr 0.25N, and In 0.75Cr 0.25N for their possible application in spin-based electronic devices. The calculated spin-polarized band structures, electronic properties, and magnetic properties of these compounds reveal that Al 0.75Cr 0.25N and Ga 0.75Cr 0.25N are half-metallic dilute magnetic semiconductors while In 0.75Cr 0.25N is metallic in nature. The present theoretical predictions provide evidence that some Cr-doped III-V nitrides can be used in spintronics devices. © 2011 TMS.

Cr-doped III-V nitrides: Potential candidates for spintronics

KAUST Repository

Amin, Bin; Arif, Suneela K.; Ahmad, Iftikhar; Maqbool, Muhammad; Ahmad, Roshan; Goumri-Said, Souraya; Prisbrey, Keith A.

2011-01-01

Studies of Cr-doped III-V nitrides, dilute magnetic alloys in the zincblende crystal structure, are presented. The objective of the work is to investigate half-metallicity in Al 0.75Cr 0.25N, Ga 0.75Cr 0.25N, and In 0.75Cr 0.25N for their possible application in spin-based electronic devices. The calculated spin-polarized band structures, electronic properties, and magnetic properties of these compounds reveal that Al 0.75Cr 0.25N and Ga 0.75Cr 0.25N are half-metallic dilute magnetic semiconductors while In 0.75Cr 0.25N is metallic in nature. The present theoretical predictions provide evidence that some Cr-doped III-V nitrides can be used in spintronics devices. © 2011 TMS.

Groundwater quality in the Piedmont and Blue Ridge crystalline-rock aquifers, eastern United States

Science.gov (United States)

Lindsey, Bruce

2017-12-07

Groundwater provides nearly 50 percent of the Nation’s drinking water. To help protect this vital resource, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Project assesses groundwater quality in aquifers that are important sources of drinking water (Burow and Belitz, 2014). The Piedmont and Blue Ridge crystalline-rock aquifers constitute one of the important areas being evaluated.

Effect of calcium on adsorptive removal of As(III) and As(V) by iron oxide-based adsorbents

KAUST Repository

Uwamariya, V.

2014-06-25

The effects of calcium on the equilibrium adsorption capacity of As(III) and As(V) onto iron oxide-coated sand (IOCS) and granular ferric hydroxide (GFH) were investigated through batch experiments, rapid small-scale column tests (RSSCT) and kinetics modelling. Batch experiments showed that at calcium concentrations≤20 mg/L, high As(III) and As(V) removal efficiencies by IOCS and GFH are achieved at pH 6. An increase of the calcium concentration to 40 and 80 mg/L reversed this trend, giving higher removal efficiencies at higher pH (8). The adsorption capacities of IOCS and GFH at an equilibrium arsenic concentration of 10 g/L were found to be between 2.0 and 3.1 mg/g for synthetic water without calcium and between 2.8 and 5.3 mg/g when 80 mg/L of calcium was present at the studied pH values. After 10 hours of filter run in RSSCT, approximately 1000 empty bed volumes, the ratios of C/Co for As(V) were 26% and 18% for calcium-free model water; and only 1% and 0.2% after addition of 80 mg/L of Ca for filter columns with IOCS and GFH, respectively. The adsorption of As(III) and As(V) onto GFH follows a second-order reaction, with and without addition of calcium. The adsorption of As(III) and As(V) onto IOCS follows a first-order reaction without calcium addition, and moves to the second-reaction-order kinetics when calcium is added. Based on the intraparticle diffusion model, the main controlling mechanism for As(III) adsorption is intraparticle diffusion, while surface diffusion contributes greatly to the adsorption of As(V).

cAMP-dependent phosphorylation of bovine lens alpha-crystallin

International Nuclear Information System (INIS)

Spector, A.; Chiesa, R.; Sredy, J.; Garner, W.

1985-01-01

This communication reports that the A1 and B1 chains of bovine lens alpha-crystallin are phosphorylated. The conclusion is based on the following evidence: (i) When soluble preparations from lens cortex are incubated with [gamma- 32 P]ATP, a cAMP-dependent labeling of a high molecular weight protein is obtained. (ii) After NaDodSO 4 /PAGE, the label is found in two bands with Mr 22,000 and 20,000, corresponding to the B and A chains of alpha-crystallin, respectively. (iii) Isoelectric focusing indicates that the radioactivity is almost exclusively in bands with pI values of 5.58 and 6.70, corresponding to the A1 and B1 chains, respectively. (iv) Similar results are obtained in experiments of [ 32 P]orthophosphate incorporation in lens organ culture. (v) Analyses of the digested protein indicate the label is exclusively in phosphoserine. (vi) 31 P NMR analyses of native, proteolytically digested, and urea-treated alpha-crystallin gives a chemical shift of 4.6 ppm relative to 85% H 3 PO 4 at pH 7.4, suggesting that the phosphate is covalently bound to a serine in the protein. An abundance of approximately one phosphate per four or five monomer units was found. (vii) Similar results were obtained by chemical analyses of independently prepared alpha-crystallin samples. The results are consistent with the view that the A1 and B1 chains arise as result of the phosphorylation of directly synthesized A2 and B2 polypeptides. It is suggested that this metabolically controlled phosphorylation may be associated with the terminal differentiation of the lens epithelial cell and the intracellular organization of the lens fiber cell

Review of status developments of high-efficiency crystalline silicon solar cells

Science.gov (United States)

Liu, Jingjing; Yao, Yao; Xiao, Shaoqing; Gu, Xiaofeng

2018-03-01

In order to further improve cell efficiency and reduce cost in achieving grid parity, a large number of PV manufacturing companies, universities and research institutes have been devoted to a variety of low-cost and high-efficiency crystalline Si solar cells. In this article, the cell structures, characteristics and efficiency progresses of several types of high-efficiency crystalline Si solar cells that have been in small scale production or are promising in mass production are presented, including passivated emitter rear cell, tunnel oxide passivated contact solar cell, interdigitated back contact cell, heterojunction with intrinsic thin-layer cell, and heterojunction solar cells with interdigitated back contacts. Both the industrialization status and future development trend of high-efficiency crystalline silicon solar cells are also pinpointed.

Electrically driven hybrid Si/III-V Fabry-Pérot lasers based on adiabatic mode transformers.

Science.gov (United States)

Ben Bakir, B; Descos, A; Olivier, N; Bordel, D; Grosse, P; Augendre, E; Fulbert, L; Fedeli, J M

2011-05-23

We report the first demonstration of an electrically driven hybrid silicon/III-V laser based on adiabatic mode transformers. The hybrid structure is formed by two vertically superimposed waveguides separated by a 100-nm-thick SiO2 layer. The top waveguide, fabricated in an InP/InGaAsP-based heterostructure, serves to provide optical gain. The bottom Si-waveguides system, which supports all optical functions, is constituted by two tapered rib-waveguides (mode transformers), two distributed Bragg reflectors (DBRs) and a surface-grating coupler. The supermodes of this hybrid structure are controlled by an appropriate design of the tapers located at the edges of the gain region. In the middle part of the device almost all the field resides in the III-V waveguide so that the optical mode experiences maximal gain, while in regions near the III-V facets, mode transformers ensure an efficient transfer of the power flow towards Si-waveguides. The investigated device operates under quasi-continuous wave regime. The room temperature threshold current is 100 mA, the side-mode suppression ratio is as high as 20 dB, and the fiber-coupled output power is ~7 mW.

Sequential and simultaneous adsorption of Sb(III) and Sb(V) on ferrihydrite: Implications for oxidation and competition.

Science.gov (United States)

Qi, Pengfei; Pichler, Thomas

2016-02-01

Antimony (Sb) is a naturally occurring element of growing environmental concern whose toxicity, adsorption behavior and other chemical properties are similar to that of arsenic (As). However, less is known about Sb compared to As. Individual and simultaneous adsorption experiments with Sb(III) and Sb(V) were conducted in batch mode with focus on the Sb speciation of the remaining liquid phase during individual Sb(III) adsorption experiments. The simultaneous adsorption and oxidation of Sb(III) was confirmed by the appearance of Sb(V) in the solution at varying Fe/Sb ratios (500, 100 and 8) and varying pH values (3.8, 7 and 9). This newly formed Sb(V) was subsequently removed from solution at a Fe/Sb ratio of 500 or at a pH of 3.8. However, more or less only Sb(V) was observed in the liquid phase at the end of the experiments at lower Fe/Sb ratios and higher pH, indicating that competition took place between the newly formed Sb(V) and Sb(III), and that Sb(III) outcompeted Sb(V). This was independently confirmed by simultaneous adsorption experiments of Sb(III) and Sb(V) in binary systems. Under such conditions, the presence of Sb(V) had no influence on the adsorption of Sb(III) while Sb(V) adsorption was significantly inhibited by Sb(III) over a wide pH range (4-10). Thus, in the presence of ferrihydrite and under redox conditions, which allow the presence of both Sb species, Sb(V) should be the dominant species in aquatic environments, since Sb(III) is adsorbed preferentially and at the same time oxidized to Sb(V). Copyright © 2015 Elsevier Ltd. All rights reserved.

Integration, gap formation, and sharpening of III-V heterostructure nanowires by selective etching

DEFF Research Database (Denmark)

Kallesoe, C.; Mølhave, Kristian; Larsen, K. F.

2010-01-01

Epitaxial growth of heterostructure nanowires allows for the definition of narrow sections with specific semiconductor composition. The authors demonstrate how postgrowth engineering of III-V heterostructure nanowires using selective etching can form gaps, sharpening of tips, and thin sections...... lithography is used for deposition of catalyst particles on trench sidewalls and the lateral growth of III-V nanowires is achieved from such catalysts. The selectivity of a bromine-based etch on gallium arsenide segments in gallium phosphide nanowires is examined, using a hydrochloride etch to remove the III...

Epigenetic regulation of αA-crystallin in high myopia-induced dark nuclear cataract.

Directory of Open Access Journals (Sweden)

Xiang-Jia Zhu

Full Text Available PURPOSE: To assess the etiology of early-onset dark nucleus in high-myopic patients and its relationship with the epigenetic regulation of αA-crystallin (CRYAA. METHODS: We reviewed clinical data from patients who underwent cataract surgery at our center in 2012. Lens epithelial samples were collected during capsulorhexis, whereas young lens epithelium was donated. Cataract type and severity were graded according to the Lens Opacity Classification System III (LOCS III. DNA methylation was analyzed by pyrosequencing the CpG islands of the CRYAA promoter in the following groups: Age-Related Cataract (ARC Nuclear Color (NC 2-3; High-Myopic Cataract (HMC NC2-3; ARC NC5-6; HMC NC5-6; and in young lenses graded NC1. We analyzed CRYAA expression by real-time polymerase chain reaction (PCR, reverse transcription PCR, and immunohistochemistry. RESULTS: The odds ratio of dark nucleus in high-myopic patients was 5.16 (95% confidence interval: 3.98-6.69; p<0.001. CpG islands in lens epithelial CRYAA promoter in the HMC NC5-6 Group exhibited the highest methylation of all the groups, but no statistically significant differences were evident between the HMC NC2-3 and ARC NC2-3 Groups. Likewise, CRYAA mRNA and protein levels in the HMC NC5-6 Group were significantly lower than the ARC NC5-6 Group and high-myopic controls. CONCLUSIONS: High myopia is a risk factor for dark nucleus. Downregulation of CRYAA via the hypermethylation of CpG islands in its promoter could underlie the earlier onset of dark nucleus in high-myopic patients.

Treatment of As(V) and As(III) by electrocoagulation using Al and Fe electrode.

Science.gov (United States)

Kuan, W H; Hu, C Y; Chiang, M C

2009-01-01

A batch electrocoagulation (EC) process with bipolar electrode and potentiodynamic polarization tests with monopolar systems were investigated as methods to explore the effects of electrode materials and initial solution pH on the As(V) and As(III) removal. The results displayed that the system with Al electrode has higher reaction rate during the initial period from 0 to 25 minutes than that of Fe electrode for alkaline condition. The pH increased with the EC time because the As(V) and As(III) removal by either co-precipitation or adsorption resulted in that the OH positions in Al-hydroxide or Fe-hydroxide were substituted by As(V) and As(III). The pH in Fe electrode system elevate higher than that in Al electrode because the As(V) removal substitutes more OH position in Fe-hydroxide than that in Al-hydroxide. EC system with Fe electrode can successfully remove the As(III) but system with Al electrode cannot because As(III) can strongly bind to the surface of Fe-hydroxide with forming inner-sphere species but weakly adsorb to the Al-hydroxide surface with forming outer-sphere species. The acidic solution can destroy the deposited hydroxide passive film then allow the metallic ions liberate into the solution, therefore, the acidic initial solution can enhance the As(V) and As(III) removal. The over potential calculation and potentiodynamic polarization tests reveal that the Fe electrode systems possess higher over potential and pitting potential than that of Al electrode system due to the fast hydrolysis of and the occurrence of Fe-hydroxide passive film.

Strain distribution and defect analysis in III-nitrides by dynamical AFM analysis

International Nuclear Information System (INIS)

Minj, Albert; Cavalcoli, Daniela; Cavallini, Anna; Gamarra, Piero; Di Forte Poisson, Marie-Antoinette

2013-01-01

Here, we report on significant material information provided by semi-contact phase-images in a wide range of hard III-nitride surfaces. We show that the phase contrast, which is fundamentally related to the energy dissipation during tip–surface interaction, is sensitive to the crystalline nature of the material and thus could potentially be used to determine the crystalline quality of thin nitride layers. Besides, we found that the structural defects, especially threading dislocations and cracks, act as selective sites where energy mainly dissipates. Consequently, in nitrides defects with very low dimensions can actually be imaged with phase-contrast imaging. (paper)

Adsorption Characteristics of Different Adsorbents and Iron(III Salt for Removing As(V from Water

Directory of Open Access Journals (Sweden)

Josip Ćurko

2016-01-01

Full Text Available The aim of this study is to determine the adsorption performance of three types of adsorbents for removal of As(V from water: Bayoxide® E33 (granular iron(III oxide, Titansorb® (granular titanium oxide and a suspension of precipitated iron(III hydroxide. Results of As(V adsorption stoichiometry of two commercial adsorbents and precipitated iron(III hydroxide in tap and demineralized water were fitted to Freundlich and Langmuir adsorption isotherm equations, from which adsorption constants and adsorption capacity were calculated. The separation factor RL for the three adsorbents ranged from 0.04 to 0.61, indicating effective adsorption. Precipitated iron(III hydroxide had the greatest, while Titansorb had the lowest capacity to adsorb As(V. Comparison of adsorption from tap or demineralized water showed that Bayoxide and precipitated iron(III hydroxide had higher adsorption capacity in demineralized water, whereas Titansorb showed a slightly higher capacity in tap water. These results provide mechanistic insights into how commonly used adsorbents remove As(V from water.

Exploration of GaInT1P and Related T1-Containing III-V Alloys for Photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Friedman, D.J.; Kibbler, A.E.; Kurtz, S.R.

1998-11-02

This paper discusses the results of an attempt to grow GaInTlP for application as a 1-eV material for the third junction of a GaInP/GaAs/3rd-junction high-efficiency solar cell. Although early indications from the literature were promising, we are unable to produce crystalline homogeneous material, and so we conclude that this material is not a promising candidate for such applications as photovoltaics.

Zero lattice mismatch and twin-free single crystalline ScN buffer layers for GaN growth on silicon

Energy Technology Data Exchange (ETDEWEB)

Lupina, L.; Zoellner, M. H.; Dietrich, B.; Capellini, G. [IHP, Im Technologiepark 25, 15236 Frankfurt, Oder (Germany); Niermann, T.; Lehmann, M. [Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin (Germany); Thapa, S. B.; Haeberlen, M.; Storck, P. [SILTRONIC AG, Hanns-Seidel-Platz 4, 81737 München (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt, Oder (Germany); BTU Cottbus, Konrad-Zuse-Str. 1, 03046 Cottbus (Germany)

2015-11-16

We report the growth of thin ScN layers deposited by plasma-assisted molecular beam epitaxy on Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) substrates. Using x-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we find that ScN films grown at 600 °C are single crystalline, twin-free with rock-salt crystal structure, and exhibit a direct optical band gap of 2.2 eV. A high degree of crystalline perfection and a very good lattice matching between ScN and GaN (misfit < 0.1%) makes the ScN/Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} buffer system a very promising template for the growth of high quality GaN layers on silicon.

Monte-Carlo simulation of crystallographical pore growth in III-V-semiconductors

International Nuclear Information System (INIS)

Leisner, Malte; Carstensen, Juergen; Foell, Helmut

2011-01-01

The growth of crystallographical pores in III-V-semiconductors can be understood in the framework of a simple model, which is based on the assumption that the branching of pores is proportional to the current density at the pore tips. The stochastic nature of this model allows its implementation into a three-dimensional Monte-Carlo-simulation of pore growth. The simulation is able to reproduce the experimentally observed crysto pore structures in III-V-semiconductors in full quantitative detail. The different branching probabilities for different semiconductors, as well as doping levels, can be deduced from the specific passivation behavior of the semiconductor-electrolyte-interface at the pore tips.

Structure and spectroscopic study of aqueous Fe(III)-As(V) complexes using UV-Vis, XAS and DFT-TDDFT.

Science.gov (United States)

Chai, Liyuan; Yang, Jinqin; Zhang, Ning; Wu, Pin-Jiun; Li, Qingzhu; Wang, Qingwei; Liu, Hui; Yi, Haibo

2017-09-01

Aqueous complexes between ferric (Fe(III)) and arsenate (As(V)) are indispensable for understanding the mobility of arsenic (As) in Fe(III)-As(V)-rich systems. In this study, aqueous Fe(III)-As(V) complexes, FeH 2 AsO 4 2+ and FeHAsO 4 + , were postulated based on the qualitative analysis of UV-Vis spectra in both Fe(III)-As(V)-HClO 4 and Fe(III)-As(V)-H 2 SO 4 systems. Subsequently, monodentate structures were evidenced by Fe K-edge EXAFS and modeled as [FeH 2 AsO 4 (H 2 O) 5 ] 2+ and [FeHAsO 4 (H 2 O) 5 ] + by DFT. The feature band at ∼280 nm was verified as electron excitation chiefly from Fe-As-bridged O atoms to d-orbital of Fe in [FeH 2 AsO 4 (H 2 O) 5 ] 2+ and [FeHAsO 4 (H 2 O) 5 ] + . The structural and spectral information of Fe(III)-As(V) complexes will enable future speciation analysis in Fe(III)-As(V)-rich system. Copyright © 2017. Published by Elsevier Ltd.

Transferable tight-binding model for strained group IV and III-V materials and heterostructures

Science.gov (United States)

Tan, Yaohua; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy B.; Klimeck, Gerhard

2016-07-01

It is critical to capture the effect due to strain and material interface for device level transistor modeling. We introduce a transferable s p3d5s* tight-binding model with nearest-neighbor interactions for arbitrarily strained group IV and III-V materials. The tight-binding model is parametrized with respect to hybrid functional (HSE06) calculations for varieties of strained systems. The tight-binding calculations of ultrasmall superlattices formed by group IV and group III-V materials show good agreement with the corresponding HSE06 calculations. The application of the tight-binding model to superlattices demonstrates that the transferable tight-binding model with nearest-neighbor interactions can be obtained for group IV and III-V materials.

Highly crystalline zinc incorporated hydroxyapatite nanorods' synthesis, characterization, thermal, biocompatibility, and antibacterial study

Science.gov (United States)

Udhayakumar, Gayathri; Muthukumarasamy, N.; Velauthapillai, Dhayalan; Santhosh, Shanthi Bhupathi

2017-10-01

Highly crystalline zinc incorporated hydroxyapatite (Zn-HAp) nanorods have been synthesized using microwave irradiation method. To improve bioactivity and crystallinity of pure HAp, zinc was incorporated into it. As-synthesized samples were characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction, field-emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), and the thermal and crystallinity behavior of Zn-HAp nanoparticle were studied by thermogravimetry (TGA) and differential scanning calorimetry (DSC). Antibacterial activity of the as-synthesized nanorods was evaluated against two prokaryotic strains ( Escherichia coli and Staphylococcus aureus). The FT-IR studies show the presence of hydroxide and phosphate functional groups. HRTEM and FESEM images showed highly crystalline rod-shaped nanoparticles with the diameter of about 50-60 nm. EDAX revealed the presence of Ca, Zn, P, and O in the prepared samples. The crystallinity and thermal stability were further confirmed by TGA-DSC analysis. The biocompatibility evaluation results promoted that the Zn-HAp nanorods are biologically active apatites and potentially promising bone-substitute biomaterials for orthopaedic application.

Epitaxial III-V nanowires on silicon for vertical devices

NARCIS (Netherlands)

Bakkers, E.P.A.M.; Borgström, M.T.; Einden, Van Den W.; Weert, van M.H.M.; Helman, A.; Verheijen, M.A.

2006-01-01

We show the epitaxial integration of III-V semiconductor nanowires with silicon technology. The wires are grown by the Vapor-Liquid-Solid (VLS) mechanism with laser ablation as well as metal organic vapor phase epitaxy. The VLS growth enables the fabrication of complex axial and radial

Facile "modular assembly" for fast construction of a highly oriented crystalline MOF nanofilm.

Science.gov (United States)

Xu, Gang; Yamada, Teppei; Otsubo, Kazuya; Sakaida, Shun; Kitagawa, Hiroshi

2012-10-10

The preparation of crystalline, ordered thin films of metal-organic frameworks (MOFs) will be a critical process for MOF-based nanodevices in the future. MOF thin films with perfect orientation and excellent crystallinity were formed with novel nanosheet-structured components, Cu-TCPP [TCPP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin], by a new "modular assembly" strategy. The modular assembly process involves two steps: a "modularization" step is used to synthesize highly crystalline "modules" with a nanosized structure that can be conveniently assembled into a thin film in the following "assembly" step. With this method, MOF thin films can easily be set up on different substrates at very high speed with controllable thickness. This new approach also enabled us to prepare highly oriented crystalline thin films of MOFs that cannot be prepared in thin-film form by traditional techniques.

V6O13 films by control of the oxidation state from aqueous precursor to crystalline phase.

Science.gov (United States)

Peys, Nick; Ling, Yun; Dewulf, Daan; Gielis, Sven; De Dobbelaere, Christopher; Cuypers, Daniel; Adriaensens, Peter; Van Doorslaer, Sabine; De Gendt, Stefan; Hardy, An; Van Bael, Marlies K

2013-01-28

An aqueous deposition process for V(6)O(13) films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance ((51)V-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resulting vanadium(IV) species in the aqueous solution are identified as mononuclear citrato-oxovanadate(IV) complexes by Electron Paramagnetic Resonance (EPR) and Fourier Transform Infra-Red (FTIR) spectroscopy. This precursor is successfully employed for the deposition of uniform, thin films. The optimal deposition and annealing conditions for the formation of crystalline V(6)O(13), including the control of the vanadium oxidation state, are determined through an elaborate study of processing temperature and O(2) partial pressure. To ensure a sub 100 nm adjustable film thickness, a non-oxidative intermediate thermal treatment is carried out at the end of each deposition cycle, allowing maximal precursor decomposition while still avoiding V(IV) oxidation. The resulting surface hydrophilicity, indispensable for the homogeneous deposition of the next layer, is explained by an increased surface roughness and the increased availability of surface vanadyl groups. Crystalline V(6)O(13) with a preferential (002) orientation is obtained after a post deposition annealing in a 0.1% O(2) ambient for thin films with a thickness of 20 nm.

As(III) oxidation by active chlorine and subsequent removal of As(V) by Al13 polymer coagulation using a novel dual function reagent.

Science.gov (United States)

Hu, Chengzhi; Liu, Huijuan; Chen, Guixia; Jefferson, William A; Qu, Jiuhui

2012-06-19

An electrochemically prepared water treatment reagent containing a high concentration of Al(13) polymer and active chlorine (PACC) showed promising potential for the removal of As(III) due to the combined function of oxidation and coagulation. The results indicated that PACC was effective for As(III) removal through oxidation by the active chlorine and subsequent removal of As(V) by coagulation with the Al(13) polymer. The As(III) was oxidized to As(V) by active chlorine in PACC, with a stoichiometric rate of 0.99 mg Cl(2)/mg As(III). The Al(13) polymer was the most active Al species responsible for As(V) removal in PACC. To meet As drinking water standards the stoichiometric weight ratio of Cl(2)/Al within PACC was 0.09 for the treatment of As(III). Considering the process of As(III) oxidation and As(V) coagulation together, the optimal pH conditions for the removal of As by PACC was within the neutral range, which facilitated the reaction of As(III) with active chlorine and favored the formation of Al hydroxide flocs. The presence of humic acid reduced the As(III) removal efficiency of PACC due to its negative influence on subsequent As(V) coagulation, and disinfection byproduct yields were very low in the presence of insufficient or stoichiometric active chlorine.

Theory of ferromagnetic (III,Mn)V semiconductors

Czech Academy of Sciences Publication Activity Database

Jungwirth, Tomáš; Sinova, J.; Mašek, Jan; Kučera, Jan; MacDonald, A. H.

2006-01-01

Roč. 78, - (2006), s. 809-859 ISSN 0034-6861 R&D Projects: GA MŠk LC510; GA ČR GA202/05/0575 Grant - others:EPSRC(GB) GR/S81407/01; U.S. Department of Energy(US) DE-FG03-02ER45958; U.S. Office of Naval research(US) OMR-N000140610122 Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic semiconductors * (III,Mn)V compounds Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 33.508, year: 2006

Radiation Effects in III-V Nanowire Devices

Science.gov (United States)

2016-09-01

fabrication of an in-plane nanowire (NW) GaAs metal-oxide-semiconductor field- effect transistor (MOSFET) by focused -ion beam (FIB) etching and chemical...8725 John J. Kingman Road, MS 6201 Fort Belvoir, VA 22060-6201 T E C H N IC A L R E P O R T DTRA-TR-16-94 Radiation Effects in III-V...5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING / MONITORING AGENCY

H{sub 2}O{sub 2}-molecular beam epitaxy of high quality ZnO

Energy Technology Data Exchange (ETDEWEB)

El Shaer, A.; Bakin, A.; Che Mofor, A.; Kreye, M.; Waag, A. [Technical University Braunschweig, Institute of Semiconductor Technology, Braunschweig (Germany); Blaesing, J.; Krost, A. [Otto-von-Guericke-University, Institute of Experimental Physics, Magdeburg (Germany); Stoimenos, J. [Aristotele University, Physics Department, Thessaloniki (Greece); Pecz, B. [Hungarian Academy of Sciences, Research Institute for Technical Physics and Materials Science, P.O. Box 49, Budapest (Hungary)

2007-07-15

We have studied the growth and characterization of ZnO epilayers on (0001)-sapphire by H{sub 2}O{sub 2}-molecular beam epitaxy (MBE). A high temperature (HT) MgO buffer followed by a low-temperature ZnO buffer was introduced in order to accommodate the lattice mismatch between ZnO and sapphire. The surface morphology of the samples was studied using atomic force microscopy (AFM), and scanning electron microscopy (SEM). The crystalline quality of the layers was investigated by employing high resolution X-ray diffractometry (HRXRD) and high resolution transmission electron microscopy (HRTEM). The electrical properties of the grown ZnO layers were studied by Hall-effect measurements in a standard van der Pauw configuration. The measured surface roughness for the best layers is as low as 0.26 nm rms. HRXRD measurements of the obtained ZnO layers show excellent quality of the single crystalline ZnO heteroepitaxially grown on (0001)-sapphire with a HT MgO buffer layers. The influence of the growth conditions on the crystalline quality is discussed. The FWHM of the HRXRD (0002) rocking curves measured for the 2-inch ZnO-on-sapphire is as low as 27 arcsec with a very high lateral homogeneity across the whole 2-inch ZnO epilayers. The results indicate that H{sub 2}O{sub 2}-MBE is a suitable technique to fabricate ZnO epilayers of very high quality. (orig.)

Crystalline ceramics: Waste forms for the disposal of weapons plutonium

International Nuclear Information System (INIS)

Ewing, R.C.; Lutze, W.; Weber, W.J.

1995-05-01

At present, there are three seriously considered options for the disposition of excess weapons plutonium: (i) incorporation, partial burn-up and direct disposal of MOX-fuel; (ii) vitrification with defense waste and disposal as glass ''logs''; (iii) deep borehole disposal (National Academy of Sciences Report, 1994). The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium

Adsorção de arsênio(V pela quitosana ferro - III reticulada Asorption of arsenic (V by crosslinked iron-III-chitosan

Directory of Open Access Journals (Sweden)

Tathyane Fagundes

2008-01-01

Full Text Available The removal of As(V by a crosslinked iron(III-chitosan adsorbent was evaluated under various conditions. The adsorption capacity of CH-FeCL was around 54 mg/g of As(V. The kinetics of adsorption obeys a pseudo-first-order model with rate constants equal to 0.022, 0.028, and 0.033 min-1 at 15, 25 and 35 ºC respectively. Adsorption data were well described by the Langmuir model, although they could be modeled also by the Langmuir-Freundlich equation. The maximum adsorption capacity, calculated with the Langmuir model, was 127 mg g-1 of As(V. The inhibition by competing anions is dependant on their kind and valence.

Optimization of the silicon subcell for III-V on silicon multijunction solar cells: Key differences with conventional silicon technology

Science.gov (United States)

García-Tabarés, Elisa; Martín, Diego; García, Iván; Lelièvre, Jean François; Rey-Stolle, Ignacio

2012-10-01

Dual-junction solar cells formed by a GaAsP or GaInP top cell and a silicon (Si) bottom cell seem to be attractive candidates to materialize the long sought-for integration of III-V materials on Si for photovoltaic (PV) applications. Such integration would offer a cost breakthrough for PV technology, unifying the low cost of Si and the efficiency potential of III-V multijunction solar cells. The optimization of the Si solar cells properties in flat-plate PV technology is well-known; nevertheless, it has been proven that the behavior of Si substrates is different when processed in an MOVPE reactor In this study, we analyze several factors influencing the bottom subcell performance, namely, 1) the emitter formation as a result of phosphorus diffusion; 2) the passivation quality provided by the GaP nucleation layer; and 3) the process impact on the bottom subcell PV properties.

Crystalline to amorphous transformation in silicon

International Nuclear Information System (INIS)

Cheruvu, S.M.

1982-09-01

In the present investigation, an attempt was made to understand the fundamental mechanism of crystalline-to-amorphous transformation in arsenic implanted silicon using high resolution electron microscopy. A comparison of the gradual disappearance of simulated lattice fringes with increasing Frenkel pair concentration with the experimental observation of sharp interfaces between crystalline and amorphous regions was carried out leading to the conclusion that when the defect concentration reaches a critical value, the crystal does relax to an amorphous state. Optical diffraction experiments using atomic models also supported this hypothesis. Both crystalline and amorphous zones were found to co-exist with sharp interfaces at the atomic level. Growth of the amorphous fraction depends on the temperature, dose rate and the mass of the implanted ion. Preliminary results of high energy electron irradiation experiments at 1.2 MeV also suggested that clustering of point defects occurs near room temperature. An observation in a high resolution image of a small amorphous zone centered at the core of a dislocation is presented as evidence that the nucleation of an amorphous phase is heterogeneous in nature involving clustering or segregation of point defects near existing defects

GAGG:ce single crystalline films: New perspective scintillators for electron detection in SEM.

Science.gov (United States)

Bok, Jan; Lalinský, Ondřej; Hanuš, Martin; Onderišinová, Zuzana; Kelar, Jakub; Kučera, Miroslav

2016-04-01

Single crystal scintillators are frequently used for electron detection in scanning electron microscopy (SEM). We report gadolinium aluminum gallium garnet (GAGG:Ce) single crystalline films as a new perspective scintillators for the SEM. For the first time, the epitaxial garnet films were used in a practical application: the GAGG:Ce scintillator was incorporated into a SEM scintillation electron detector and it showed improved image quality. In order to prove the GAGG:Ce quality accurately, the scintillation properties were examined using electron beam excitation and compared with frequently used scintillators in the SEM. The results demonstrate excellent emission efficiency of the GAGG:Ce single crystalline films together with their very fast scintillation decay useful for demanding SEM applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Phosphorylation of αB-crystallin: Role in stress, aging and patho-physiological conditions.

Science.gov (United States)

Bakthisaran, Raman; Akula, Kranthi Kiran; Tangirala, Ramakrishna; Rao, Ch Mohan

2016-01-01

αB-crystallin, once thought to be a lenticular protein, is ubiquitous and has critical roles in several cellular processes that are modulated by phosphorylation. Serine residues 19, 45 and 59 of αB-crystallin undergo phosphorylation. Phosphorylation of S45 is mediated by p44/42 MAP kinase, whereas S59 phosphorylation is mediated by MAPKAP kinase-2. Pathway involved in S19 phosphorylation is not known. The review highlights the role of phosphorylation in (i) oligomeric structure, stability and chaperone activity, (ii) cellular processes such as apoptosis, myogenic differentiation, cell cycle regulation and angiogenesis, and (iii) aging, stress, cardiomyopathy-causing αB-crystallin mutants, and in other diseases. Depending on the context and extent of phosphorylation, αB-crystallin seems to confer beneficial or deleterious effects. Phosphorylation alters structure, stability, size distribution and dynamics of the oligomeric assembly, thus modulating chaperone activity and various cellular processes. Phosphorylated αB-crystallin has a tendency to partition to the cytoskeleton and hence to the insoluble fraction. Low levels of phosphorylation appear to be protective, while hyperphosphorylation has negative implications. Mutations in αB-crystallin, such as R120G, Q151X and 464delCT, associated with inherited myofibrillar myopathy lead to hyperphosphorylation and intracellular inclusions. An ongoing study in our laboratory with phosphorylation-mimicking mutants indicates that phosphorylation of R120GαB-crystallin increases its propensity to aggregate. Phosphorylation of αB-crystallin has dual role that manifests either beneficial or deleterious consequences depending on the extent of phosphorylation and interaction with cytoskeleton. Considering that disease-causing mutants of αB-crystallin are hyperphosphorylated, moderation of phosphorylation may be a useful strategy in disease management. This article is part of a Special Issue entitled Crystallin

Manipulating Ion Migration for Highly Stable Light-Emitting Diodes with Single-Crystalline Organometal Halide Perovskite Microplatelets.

Science.gov (United States)

Chen, Mingming; Shan, Xin; Geske, Thomas; Li, Junqiang; Yu, Zhibin

2017-06-27

Ion migration has been commonly observed as a detrimental phenomenon in organometal halide perovskite semiconductors, causing the measurement hysteresis in solar cells and ultrashort operation lifetimes in light-emitting diodes. In this work, ion migration is utilized for the formation of a p-i-n junction at ambient temperature in single-crystalline organometal halide perovskites. The junction is subsequently stabilized by quenching the ionic movement at a low temperature. Such a strategy of manipulating the ion migration has led to efficient single-crystalline light-emitting diodes that emit 2.3 eV photons starting at 1.8 V and sustain a continuous operation for 54 h at ∼5000 cd m -2 without degradation of brightness. In addition, a whispering-gallery-mode cavity and exciton-exciton interaction in the perovskite microplatelets have both been observed that can be potentially useful for achieving electrically driven laser diodes based on single-crystalline organometal halide perovskite semiconductors.

Testing of full size high current superconductors in SULTAN III

Science.gov (United States)

Blau, B.; Rohleder, I.; Vecsey, G.; Pasotti, G.; Ricci, M. V.; Sacchetti, N.; Bruzzone, P.; Katheder, H.; Mitchell, N.; Bessette, D.

1994-07-01

The high field test facility SULTAN III in operation at PSI/Switzerland tests full size industrial prototype superconductors for fusion applications such as ITER. The facility provides a background field of up to 11 T over a length of 58 cm. A 50 kA superconducting transformer works as a very low noise current source which allows a criterion of 0.1 mu V/cm to determine the superconducting to normal transition. Three 3.6 m long cable-in-conduit conductors based on both NbTi and Nb3Sn, developed by different manufacturers, suitable for the central solenoid and toroidal field coils of ITER, have been tested so far. This paper presents the results of extensive measurements of critical current and current sharing temperature of the Nb3Sn conductors in the 8 - 11 T range for temperatures between 4.5 K and 11 K. Voltage versus current curves have been analyzed with respect to the n value. The manufacturing of a high quality joint between two Nb3Sn conductors after heat treatment is reported, together with some measurements of the joint resistance.

Testing of full size high current superconductors in SULTAN III

International Nuclear Information System (INIS)

Blau, B.; Rohleder, I.; Vecsey, G.

1994-01-01

The high field test facility SULTAN III in operation at PSI/Switzerland tests full size industrial prototype superconductors for fusion applications such as ITER. The facility provides a background field of up to 11 T over a length of 58 cm. A 50 kA superconducting transformer works as a very low noise current source which allows a criterion of 0.1 μV/cm to determine the superconducting to normal transition. Three 3.6 m long cable-in-conduit conductors based on both NbTi and Nb 3 Sn, developed by different manufacturers, suitable for the central solenoid and toroidal field coils of ITER, have been tested so far. This paper presents the results of extensive measurements of critical current and current sharing temperature of the Nb 3 Sn conductors in the 8--11 T range for temperatures between 4.5 K and 11 K Voltage versus current curves have been analyzed with respect to the n value. The manufacturing of a high quality joint between two Nb 3 Sn conductors after heat treatment is reported, together with some measurements of the joint resistance

SHINE-III. Simple code for skyshine dose calculation up to 3 GeV neutrons

Energy Technology Data Exchange (ETDEWEB)

Tsukiyama, Toshihisa; Tayama, Ryuichi; Handa, Hiroyuki [Hitachi Engineering Co. Ltd., Ibaraki (Japan)] [and others

2000-03-01

Skyshine dose at site boundary is considered as one of the most fundamental issues to get approval of constructing nuclear installations. Skyshine conical beam response functions (CBRF) for high energy neutrons up to 3 GeV are obtained using NMTC-JAERI and MCNP code. This CBRF is fitted to the four parameters equation. Simple code named SHINE-III using this equation with updated data is developed. (author)

STABILITY: AN INVESTIGATION OF AS(III)/AS(V) STABILITY IN IRON RICH DRINKING WATER MATRICES

Science.gov (United States)

Arsenic in drinking water is predominantly inorganic arsenic. The two oxidation states of inorganic arsenic are As(III)(pKa=9.3) and As(V)(pKa2=6.9). The distribution of As(III) and AS(V) in a water is dependent on the redox potential of the water. The actual distribution can ...

High-Performance Flexible Single-Crystalline Silicon Nanomembrane Thin-Film Transistors with High- k Nb2O5-Bi2O3-MgO Ceramics as Gate Dielectric on a Plastic Substrate.

Science.gov (United States)

Qin, Guoxuan; Zhang, Yibo; Lan, Kuibo; Li, Lingxia; Ma, Jianguo; Yu, Shihui

2018-04-18

A novel method of fabricating flexible thin-film transistor based on single-crystalline Si nanomembrane (SiNM) with high- k Nb 2 O 5 -Bi 2 O 3 -MgO (BMN) ceramic gate dielectric on a plastic substrate is demonstrated in this paper. SiNMs are successfully transferred to a flexible polyethylene terephthalate substrate, which has been plated with indium-tin-oxide (ITO) conductive layer and high- k BMN ceramic gate dielectric layer by room-temperature magnetron sputtering. The BMN ceramic gate dielectric layer demonstrates as high as ∼109 dielectric constant, with only dozens of pA current leakage. The Si-BMN-ITO heterostructure has only ∼nA leakage current at the applied voltage of 3 V. The transistor is shown to work at a high current on/off ratio of above 10 4 , and the threshold voltage is ∼1.3 V, with over 200 cm 2 /(V s) effective channel electron mobility. Bending tests have been conducted and show that the flexible transistors have good tolerance on mechanical bending strains. These characteristics indicate that the flexible single-crystalline SiNM transistors with BMN ceramics as gate dielectric have great potential for applications in high-performance integrated flexible circuit.

Morphology of interior interfaces in dilute nitride III/V material systems; Morphologie innerer Grenzflaechen in verduennt stickstoffhaltigen III/V-Materialsystemen

Energy Technology Data Exchange (ETDEWEB)

Oberhoff, S.

2007-12-03

This study aims to clarify structure formation processes in dilute N-containing III/V-based material systems, using highly selective etching methods and subsequent atomic force microscopy (AFM) to expose and analyse interior interfaces. In the first part of this study it was directly proved for the first time that adding Sb during growth interruption inhibits the GI-induced structural phase transition and reduces the diffusivity on GaAs and (GaIn)(NAs) surfaces. However, applying Sb during GI does not affect the driving force of the structural phase transition. Therefore a fundamental analysis about the incorporation of Sb into GaAs, Ga(NAs) and (GaIn)(NAs) was carried out in the second part of the study. Using a combination of high resolution X-ray diffraction, transmission electron microscopy and SIMS measurements, it was verified that incorporating Sb into (GaIn)(NAs) causes an increase of the In content and a decrease of the N content. In the third part of the study, novel etching methods for the GaP-based material system Ga(NAsP) are introduced which provide the opportunity to analyse structure formation processes on interior interfaces in this material system by AFM. (orig.)

Crystalline and amorphous carbon nitride films produced by high-energy shock plasma deposition

International Nuclear Information System (INIS)

Bursilll, L.A.; Peng, Julin; Gurarie, V.N.; Orlov, A.V.; Prawer, S.

1995-01-01

High-energy shock plasma deposition techniques are used to produce carbon-nitride films containing both crystalline and amorphous components. The structures are examined by high-resolution transmission electron microscopy, parallel-electron-energy loss spectroscopy and electron diffraction. The crystalline phase appears to be face-centered cubic with unit cell parameter approx. a=0.63nm and it may be stabilized by calcium and oxygen at about 1-2 at % levels. The carbon atoms appear to have both trigonal and tetrahedral bonding for the crystalline phase. There is PEELS evidence that a significant fraction of the nitrogen atoms have sp 2 trigonal bonds in the crystalline phase. The amorphous carbon-nitride film component varies from essentially graphite, containing virtually no nitrogen, to amorphous carbon-nitride containing up to 10 at % N, where the fraction of sp 3 bonds is significant. 15 refs., 5 figs

Fundamental Research and Development for Improved Crystalline Silicon Solar Cells: Final Subcontract Report, March 2002 - July 2006

Energy Technology Data Exchange (ETDEWEB)

Rohatgi, A.

2007-11-01

This report summarizes the progress made by Georgia Tech in the 2002-2006 period toward high-efficiency, low-cost crystalline silicon solar cells. This program emphasize fundamental and applied research on commercial substrates and manufacturable technologies. A combination of material characterization, device modeling, technology development, and complete cell fabrication were used to accomplish the goals of this program. This report is divided into five sections that summarize our work on i) PECVD SiN-induced defect passivation (Sections 1 and 2); ii) the effect of material inhomogeneity on the performance of mc-Si solar cells (Section 3); iii) a comparison of light-induced degradation in commercially grown Ga- and B-doped Czochralski Si ingots (Section 4); and iv) the understanding of the formation of high-quality thick-film Ag contacts on high sheet-resistance emitters (Section 5).

18 CFR 410.1 - Basin regulations-Water Code and Administrative Manual-Part III Water Quality Regulations.

Science.gov (United States)

2010-04-01

... Code and Administrative Manual-Part III Water Quality Regulations. 410.1 Section 410.1 Conservation of... CODE AND ADMINISTRATIVE MANUAL-PART III WATER QUALITY REGULATIONS § 410.1 Basin regulations—Water Code and Administrative Manual—Part III Water Quality Regulations. (a) The Water Code of the Delaware River...

Fabrication and characterization of high quality n-ZnO/p-GaN heterojunction light emission diodes

International Nuclear Information System (INIS)

Zheng Hao; Mei, Z.X.; Zeng, Z.Q.; Liu, Y.Z.; Guo, L.W.; Jia, J.F.; Xue, Q.K.; Zhang, Z.; Du, X.L.

2011-01-01

High quality single crystalline n-type ZnO film was grown on p-type GaN substrate using molecular beam epitaxy. Transmission electron microscopy reveals a sharp ZnO/GaN interface. Light-emitting diode was fabricated from this heterostructure, and a turn-on voltage of ∼ 3.4 V was demonstrated. We found that the emission peak shifts from violet (430 nm) to near-ultraviolet (375 nm) when the driving current increases from 0.38 mA to 3.08 mA. This intriguing phenomenon can be understood by charged carrier's radical recombination occurring at both sides of the device, and the current enhancement of ZnO emission efficiency.

Solution processed nanogap organic diodes based on liquid crystalline materials

Science.gov (United States)

Wang, Yi-Fei; Iino, Hiroaki; Hanna, Jun-ichi

2017-09-01

Co-planar nanogap organic diodes were fabricated with smectic liquid crystalline materials of the benzothienobenzothiophene (BTBT) derivative by a spin-coating technique. A high rectification ratio of the order of 106 at ±3 V was achieved when a liquid crystalline material of 2,7-didecyl benzothieno[3,2-b][1]benzothiophene (10-BTBT-10) was used in a device configuration of Al/10-BTBT-10/pentafluorobenzenethiol-treated Au on a glass substrate, which was 4 orders higher than that of the device based on non-liquid crystalline materials of 2,7-dibutyl benzothieno[3,2-b][1]benzothiophene (4-BTBT-4) and BTBT. Similar results were also observed when another liquid crystalline material of ω, ω'-dioctylterthiophene (8-TTP-8) and a non-liquid crystalline material of terthiophene (TTP) were used. These improved rectifications can be ascribed to the self-assembly properties and controllable molecular orientation of liquid crystalline materials, which made uniform perpendicular oriented polycrystalline films favorable for superior charge transport in nano-channels.

Ferrous Iron Oxidation under Varying pO2 Levels: The Effect of Fe(III)/Al(III) Oxide Minerals and Organic Matter.

Science.gov (United States)

Chen, Chunmei; Thompson, Aaron

2018-01-16

Abiotic Fe(II) oxidation by O 2 commonly occurs in the presence of mineral sorbents and organic matter (OM) in soils and sediments; however, this tertiary system has rarely been studied. Therefore, we examined the impacts of mineral surfaces (goethite and γ-Al 2 O 3 ) and organic matter [Suwannee River fulvic acid (SRFA)] on Fe(II) oxidation rates and the resulting Fe(III) (oxyhydr)oxides under 21 and 1% pO 2 at pH 6. We tracked Fe dynamics by adding 57 Fe(II) to 56 Fe-labeled goethite and γ-Al 2 O 3 and characterized the resulting solids using 57 Fe Mössbauer spectroscopy. We found Fe(II) oxidation was slower at low pO 2 and resulted in higher-crystallinity Fe(III) phases. Relative to oxidation of Fe(II) (aq) alone, both goethite and γ-Al 2 O 3 surfaces increased Fe(II) oxidation rates regardless of pO 2 levels, with goethite being the stronger catalyst. Goethite surfaces promoted the formation of crystalline goethite, while γ-Al 2 O 3 favored nano/small particle or disordered goethite and some lepidocrocite; oxidation of Fe(II) aq alone favored lepidocrocite. SRFA reduced oxidation rates in all treatments except the mineral-free systems at 21% pO 2 , and SRFA decreased Fe(III) phase crystallinity, facilitating low-crystalline ferrihydrite in the absence of mineral sorbents, low-crystalline lepidocrocite in the presence of γ-Al 2 O 3 , but either crystalline goethite or ferrihydrite when goethite was present. This work highlights that the oxidation rate, the types of mineral surfaces, and OM control Fe(III) precipitate composition.

30 CFR 57.22208 - Auxiliary fans (I-A, II-A, III, and V-A mines).

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Auxiliary fans (I-A, II-A, III, and V-A mines... fans (I-A, II-A, III, and V-A mines). (a) Auxiliary fans, except fans used in shops and other areas... applicable requirements of 30 CFR part 18, and be operated so that recirculation is minimized. Auxiliary fans...

Mixing of III-V compound semiconductor superlattices

International Nuclear Information System (INIS)

Mei, Ping.

1989-01-01

In this work, the methods as well as mechanisms of III-V compound superlattice mixing are discussed, with particular attention on the AlGaAs based superlattice system. Comparative studies of ion-induced mixing showed two distinct effects resulting from ion implantation followed by a thermal anneal; i.e. collisional mixing and impurity induced mixing. It was found that Ga and As ion induced mixing are mainly due to the collisional effect, where the extent of the mixing can be estimated theoretically, with the parameters of ion mass, incident energy and the implant dose. The impurity effect was dominant for Si, Ge, Be, Zn and Te. Quantitative studies of impurity induced mixing have been conducted on samples doped with Si or Te during the growth process. It was discovered that Si induced AlGaAs superlattice mixing yielded an activation energy of approximately 4 eV for the Al diffusion coefficient with a high power law dependence of the prefactor on the Si concentration. In the Te doped AlGaAs superlattice the Al diffusion coefficient exhibited an activation energy of ∼3.0 eV, with a prefactor approximately proportional to the Te concentration. These results are of importance in examining the current diffusion models. Zn and Si induced InP/InGaAs superlattice mixing are examined. It was found that Zn predominantly induces cation interdiffusion, while Si induces comparable cation and anion interdiffusion. In addition, widely dispersed Zn rich islands form with Zn residing in the InP layers in the form of Zn 3 P 2 . With unstrained starting material, the layer bandgap disparity increases due to mixing induced strain, while in the Si diffused sample the mixed region would be expected to exhibit bandgaps intermediate between those of the original layers. Semiconductor superlattice mixing shows technological potential for optoelectronic device fabrication

The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

International Nuclear Information System (INIS)

Zhao, Huaying; Magone, M Teresa; Schuck, Peter

2011-01-01

Crystallins are present in the lens at extremely high concentrations in order to provide transparency and generate a high refractive power of the lens. The crystallin families prevalent in the highest density lens tissues are γ-crystallins in vertebrates and S-crystallins in cephalopods. As shown elsewhere, in parallel evolution, both have evolved molecular refractive index increments 5–10% above those of most proteins. Although this is a small increase, it is statistically very significant and can be achieved only by very unusual amino acid compositions. In contrast, such a molecular adaptation to aid in the refractive function of the lens did not occur in crystallins that are preferentially located in lower density lens tissues, such as vertebrate α-crystallin and taxon-specific crystallins. In the current work, we apply a model of non-interacting hard spheres to examine the thermodynamic contributions of volume exclusion at lenticular protein concentrations. We show that the small concentration decrease afforded by the higher molecular refractive index increment of crystallins can amplify nonlinearly to produce order of magnitude differences in chemical activities, and lead to reduced osmotic pressure and the reduced propensity for protein aggregation. Quantitatively, this amplification sets in only at protein concentrations as high as those found in hard lenses or the nucleus of soft lenses, in good correspondence to the observed crystallin properties in different tissues and different species. This suggests that volume exclusion effects provide the evolutionary driving force for the unusual refractive properties and the unusual amino acid compositions of γ-crystallins and S-crystallins

Prospective trial of angiography and embolization for all grade III to V blunt splenic injuries: nonoperative management success rate is significantly improved.

Science.gov (United States)

Miller, Preston R; Chang, Michael C; Hoth, J Jason; Mowery, Nathan T; Hildreth, Amy N; Martin, R Shayn; Holmes, James H; Meredith, J Wayne; Requarth, Jay A

2014-04-01

Nonoperative management (NOM) of blunt splenic injury is well accepted. Substantial failure rates in higher injury grades remain common, with one large study reporting rates of 19.6%, 33.3%, and 75% for grades III, IV, and V, respectively. Retrospective data show angiography and embolization can increase salvage rates in these severe injuries. We developed a protocol requiring referral of all blunt splenic injuries, grades III to V, without indication for immediate operation for angiography and embolization. We hypothesized that angiography and embolization of high-grade blunt splenic injury would reduce NOM failure rates in this population. This was a prospective study at our Level I trauma center as part of a performance-improvement project. Demographics, injury characteristics, and outcomes were compared with historic controls. The protocol required all stable patients with grade III to V splenic injuries be referred for angiography and embolization. In historic controls, referral was based on surgeon preference. From January 1, 2010 to December 31, 2012, there were 168 patients with grades III to V spleen injuries admitted; NOM was undertaken in 113 (67%) patients. The protocol was followed in 97 patients, with a failure rate of 5%. Failure rate in the 16 protocol deviations was 25% (p = 0.02). Historic controls from January 1, 2007 to December 31, 2009 were compared with the protocol group. One hundred and fifty-three patients with grade III to V injuries were admitted during this period, 80 (52%) patients underwent attempted NOM. Failure rate was significantly higher than for the protocol group (15%, p = 0.04). Use of a protocol requiring angiography and embolization for all high-grade spleen injuries slated for NOM leads to a significantly decreased failure rate. We recommend angiography and embolization as an adjunct to NOM for all grade III to V splenic injuries. Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Optimization of growth parameters for MOVPE-grown GaSb and Ga{sub 1-x}In{sub x}Sb

Energy Technology Data Exchange (ETDEWEB)

Miya, S.S.; Wagener, V. [Department of Physics, Private Bag X 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6001 (South Africa); Botha, J.R., E-mail: reinhardt.botha@nmmu.ac.za [Department of Physics, Private Bag X 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6001 (South Africa)

2012-05-15

The triethylgallium/trimethylantimony (TEGa/TMSb) precursor combination was used for the metal-organic vapour phase epitaxial growth of GaSb at a growth temperature of 520 Degree-Sign C at atmospheric pressure. Trimethylindium was added in the case of Ga{sub 1-x}In{sub x}Sb growth. The effects of group V flux to group III flux ratio (V/III ratio) on the crystallinity and optical properties of GaSb layers are reported. It has been observed from the crystalline quality and optical properties that nominal V/III ratios of values greater than unity are required for GaSb epitaxial layers grown at this temperature. It has also been shown that Ga{sub 1-x}In{sub x}Sb can be grown using TEGa as a source of gallium species at atmospheric pressure. The relationship between Ga{sub 1-x}In{sub x}Sb vapour composition and solid composition has been studied at a V/III ratio of 0.78.

Optimization of growth parameters for MOVPE-grown GaSb and Ga1−xInxSb

International Nuclear Information System (INIS)

Miya, S.S.; Wagener, V.; Botha, J.R.

2012-01-01

The triethylgallium/trimethylantimony (TEGa/TMSb) precursor combination was used for the metal-organic vapour phase epitaxial growth of GaSb at a growth temperature of 520 °C at atmospheric pressure. Trimethylindium was added in the case of Ga 1−x In x Sb growth. The effects of group V flux to group III flux ratio (V/III ratio) on the crystallinity and optical properties of GaSb layers are reported. It has been observed from the crystalline quality and optical properties that nominal V/III ratios of values greater than unity are required for GaSb epitaxial layers grown at this temperature. It has also been shown that Ga 1−x In x Sb can be grown using TEGa as a source of gallium species at atmospheric pressure. The relationship between Ga 1−x In x Sb vapour composition and solid composition has been studied at a V/III ratio of 0.78.

On the Nature of Ultra-faint Dwarf Galaxy Candidates. I. DES1, Eridanus III, and Tucana V

Science.gov (United States)

Conn, Blair C.; Jerjen, Helmut; Kim, Dongwon; Schirmer, Mischa

2018-01-01

We use deep Gemini/GMOS-S g, r photometry to study the three ultra-faint dwarf galaxy candidates DES1, Eridanus III (Eri III), and Tucana V (Tuc V). Their total luminosities, M V (DES1) = ‑1.42 ± 0.50 and M V (Eri III) = ‑2.07 ± 0.50, and mean metallicities, [{Fe}/{{H}}]=-{2.38}-0.19+0.21 and [{Fe}/{{H}}]=-{2.40}-0.12+0.19, are consistent with them being ultra-faint dwarf galaxies, as they fall just outside the 1σ confidence band of the luminosity–metallicity relation for Milky Way satellite galaxies. However, their positions in the size–luminosity relation suggest that they are star clusters. Interestingly, DES1 and Eri III are at relatively large Galactocentric distances, with DES1 located at {D}{GC}=74+/- 4 {kpc} and Eri III at {D}{GC}=91+/- 4 {kpc}. In projection, both objects are in the tail of gaseous filaments trailing the Magellanic Clouds and have similar 3D separations from the Small Magellanic Cloud (SMC): {{Δ }}{D}{SMC,{DES}1}=31.7 kpc and {{Δ }}{D}{SMC,{Eri}{III}}=41.0 kpc, respectively. It is plausible that these stellar systems are metal-poor SMC satellites. Tuc V represents an interesting phenomenon in its own right. Our deep photometry at the nominal position of Tuc V reveals a low-level excess of stars at various locations across the GMOS field without a well-defined center. An SMC Northern Overdensity–like isochrone would be an adequate match to the Tuc V color–magnitude diagram, and the proximity to the SMC (12.°1 {{Δ }}{D}{SMC,{Tuc}{{V}}}=13 kpc) suggests that Tuc V is either a chance grouping of stars related to the SMC halo or a star cluster in an advanced stage of dissolution.

Growth of Ag-seeded III-V Nanowires and TEM Characterization

DEFF Research Database (Denmark)

Lindberg, Anna Helmi Caroline

appropriate, the density and the vertical yield were obtained. The crystal structures for the grown nanowires have been investigated with TEM.We have also performed additional growths to further understand exactly how the nanowire growth proceeds as well as to understand the limitations of using Ag as a seed......This thesis deals with growth and characterization of GaAs and InAs nanowires. Today Au nanoparticle-seeding together with self-catalyzing are the dominating techniques to grow III-V nanowires with molecular beam epitaxy. In this thesis we instead investigate the possibility to use Ag as seed...... particle for growth of GaAs and InAs nanowires. The aim with the experiments performed has been to conclude whether Ag can be used to nucleate and grow nanowires on III-V substrates with molecular beam epitaxy. To investigate this we have performed growths of GaAs nanowires on GaAs(111)B and GaAs(100...

Crystalline-to-amorphous phase transition in irradiated silicon

International Nuclear Information System (INIS)

Seidman, D.N.; Averback, R.S.; Okamoto, P.R.; Baily, A.C.

1986-01-01

The amorphous(a)-to-crystalline (c) phase transition has been studied in electron(e - ) and/or ion irradiated silicon (Si). The irradiations were performed in situ in the Argonne High Voltage Microscope-Tandem Facility. The irradiation of Si, at 0 K, with 1-MeV e - to a fluence of 14 dpa failed to induce the c-to-a transition. Whereas an irradiation, at 0 K, with 1.0 or 1.5-MeV Kr+ ions induced the c-to-a transition by a fluence of approx.0.37 dpa. Alternatively a dual irradiation, at 10 0 K, with 1.0-MeV e - and 1.0 or 1.5-MeV Kr+ to a Kr+ fluence of 1.5 dpa - where the ratio of the displacement rates for e - to ions was approx.0.5 - resulted in the Si specimen retaining a degree of crystallinity. These results are discussed in terms of the degree of dispersion of point defects in the primary state of damage and the mobilities of point defects

Substrate effects on the formation of flat Ag films on (110) surfaces of III-V compound semiconductors

International Nuclear Information System (INIS)

Chao, K.; Zhang, Z.; Ebert, P.; Shih, C.K.

1999-01-01

Ag films grown at 135 K on (110) surfaces of III-V compound semiconductors and annealed at room temperature are investigated by scanning tunneling microscopy and low-energy electron diffraction. Ag films on Ga-V semiconductors are well ordered, atomically flat, and exhibit a specific critical thickness, which is a function of the substrate material. Films grown on In-V semiconductors are still rather flat, but significantly more disordered. The (111) oriented Ag films on III-arsenides and III-phosphides exhibit a clear twofold superstructure. Films on III-antimonides exhibit threefold low-energy electron diffraction images. The morphology of the Ag films can be explained on the basis of the electronic growth mechanism. copyright 1999 The American Physical Society

Dissolution of crystalline ceramics

International Nuclear Information System (INIS)

White, W.B.

1982-01-01

The present program objectives are to lay out the fundamentals of crystalline waste form dissolution. Nuclear waste ceramics are polycrystalline. An assumption of the work is that to the first order, the release rate of a particular radionuclide is the surface-weighted sum of the release rates of the radionuclide from each crystalline form that contains it. In the second order, of course, there will be synergistic effects. There will be also grain boundary and other microstructural influences. As a first approximation, we have selected crystalline phases one at a time. The sequence of investigations and measurements is: (i) Identification of the actual chemical reactions of dissolution including identification of the solid reaction products if such occur. (ii) The rates of these reactions are then determined empirically to give what may be called macroscopic kinetics. (iii) Determination of the rate-controlling mechanisms. (iv) If the rate is controlled by surface reactions, the final step would be to determine the atomic kinetics, that is the specific atomic reactions that occur at the dissolving interface. Our concern with the crystalline forms are in two areas: The crystalline components of the reference ceramic waste form and related ceramics and the alumino-silicate phases that appear in some experimental waste forms and as waste-rock interaction products. Specific compounds are: (1) Reference Ceramic Phases (zirconolite, magnetoplumbite, spinel, Tc-bearing spinel and perovskite); (2) Aluminosilicate phases (nepheline, pollucite, CsAlSi 5 O 12 , Sr-feldspar). 5 figures, 1 table

Highly luminescent pure-red-emitting fluorinated β-diketonate europium(III) complex for full solution-processed OLEDs

Energy Technology Data Exchange (ETDEWEB)

Martins, Joao P. [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, Coimbra P-3004-516 (Portugal); Serviço de Medicina Nuclear, SESARAM E.P.E., Avenida Luís de Camões 57, Funchal 9004-514, Madeira (Portugal); Martín-Ramos, Pablo [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, Coimbra P-3004-516 (Portugal); Higher Technical School of Telecommunications Engineering, Universidad de Valladolid, Campus Miguel Delibes, Paseo Belén 15, Valladolid 47011 (Spain); Coya, Carmen, E-mail: carmen.coya@urjc.es [Escuela Superior de Ciencias Experimentales y Tecnología (ESCET), Universidad Rey Juan Carlos, Madrid 28933 (Spain); Silva, Manuela Ramos [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, Coimbra P-3004-516 (Portugal); Eusebio, M. Ermelinda S. [Chemistry Department, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Coimbra P-3004-535 (Portugal); Andrés, Alicia de [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (CSIC), Cantoblanco, Madrid 28049 (Spain); Álvarez, Ángel L. [Escuela Superior de Ciencias Experimentales y Tecnología (ESCET), Universidad Rey Juan Carlos, Madrid 28933 (Spain); Martín-Gil, Jesús [Advanced Materials Laboratory, ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, Palencia 34004 (Spain)

2015-03-15

Current manufacturing technologies for OLEDs involve the use of expensive high vacuum techniques and call for thermal stability requirements which are not fulfilled by many materials. These problems disappear when the OLED films are deposited directly from solution. In this study, we have designed, synthesized and characterized a novel octacoordinated complex, Tris(1-(4-chlorophenyl)-4,4,4-trifluoro-1, 3-butanedionate)mono(bathophenanthroline) europium(III), to be used as a “complex-only” emissive layer in wet-processed OLEDs. Upon excitation in the UV region, very efficient energy transfer from the ligands to Eu{sup 3+} takes place, giving rise to intense red emission with very high monochromaticity (R=19), both in powder and as a thin film. The decay times of 754 µs (powder) and 620 µs (thin film) are comparable to those of the most efficient Eu{sup 3+} β-diketonate complexes reported to date. The same energy transfer leading to saturated red and narrow emission is also observed in the OLED device (glass/ITO/PEDOT:PSS/[Eu(cbtfa){sub 3}(bath)]/Ca/Al) when biased at >5.2 V. Its high quantum efficiency (∼60%), good thermal stability up to 200 °C and adequate thin film forming properties make this material a promising chromophore for cost-effective OLEDs. - Highlights: • A highly fluorinated europium(III) octacoordinated complex, [Eu(cbtfa)3(bath)], has been synthesized and its structure elucidated by single crystal X-ray diffraction. • The chosen coordination environment is well-suited for sensitizing the luminescence of the Eu{sup 3+} ion, achieving very efficient energy transfer from the organic ligands (excited in the UV region) to the rare earth ion, leading to highly efficient (Q∼60% in crystalline powder and Q∼50% in thin film) and saturated red photoluminescence. • The material has also been integrated into a single active layer, full solution-processed OLED, with ITO/PEDOT:PSS/[Eu(cbtfa)3(bath)]/ Ca/Al structure.

Qinshan Phase III (CANDU) nuclear power project quality assurance

International Nuclear Information System (INIS)

Wang Lingen; Du Jinxiang

2001-01-01

The completion and implementation of quality assurance system of Qinshan Phase III (CANDU) nuclear power project are presented. Some comments and understanding with consideration of the project characteristics are put forward

III-V semiconductors for photoelectrochemical applications: surface preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Fertig, Dominic; Schaechner, Birgit; Calvet, Wofram; Kaiser, Bernhard; Jaegermann, Wolfram [TU Darmstadt, Fachbereich Materialwissenschaft, Fachgebiet Oberflaechenforschung (Germany)

2011-07-01

III-V semiconductors are promising reference systems for photoelectrochemical energy conversion. Therefore we have studied the influence of different acids and acidic solutions on the etching of p-doped gallium-arsenide and gallium-phosphide single crystal surfaces. From our experiments we conclude, that etching with HCl and subsequent annealing up to 450 C gives the best results for the removal of the carbonates and the oxides without affecting the quality of the sample. By treating the surfaces with ''piranha''-solution (H{sub 2}SO{sub 4}:H{sub 2}O{sub 2}:H{sub 2}O/7:2:1), the creation of an oxide layer with well defined thickness can be achieved. For the creation of an efficient photoelectrochemical cell, Pt nanoparticles have been deposited from solution. These surfaces are then characterized by photoelectron spectroscopy and AFM. Further electrochemical measurements try to correlate the effect of the surface cleaning and the Pt deposition on the photoactivity of the GaAs- and GaP-semiconductors.

Nanostructured iron(III)-copper(II) binary oxide: a novel adsorbent for enhanced arsenic removal from aqueous solutions.

Science.gov (United States)

Zhang, Gaosheng; Ren, Zongming; Zhang, Xiwang; Chen, Jing

2013-08-01

To obtain a highly efficient and low-cost adsorbent for arsenic removal from water, a novel nanostructured Fe-Cu binary oxide was synthesized via a facile co-precipitation method. Various techniques including BET surface area measurement, powder XRD, SEM, and XPS were used to characterize the synthetic Fe-Cu binary oxide. It showed that the oxide was poorly crystalline, 2-line ferrihydrite-like and was aggregated with many nanosized particles. Laboratory experiments were performed to investigate adsorption kinetics, adsorption isotherms, pH adsorption edge and regeneration of spent adsorbent. The results indicated that the Fe-Cu binary oxide with a Cu: Fe molar ratio of 1:2 had excellent performance in removing both As(V) and As(III) from water, and the maximal adsorption capacities for As(V) and As(III) were 82.7 and 122.3 mg/g at pH 7.0, respectively. The values are favorable, compared to those reported in the literature using other adsorbents. The coexisting sulfate and carbonate had no significant effect on arsenic removal. However, the presence of phosphate obviously inhibited the arsenic removal, especially at high concentrations. Moreover, the Fe-Cu binary oxide could be readily regenerated using NaOH solution and be repeatedly used. The Fe-Cu binary oxide could be a promising adsorbent for both As(V) and As(III) removal because of its excellent performance, facile and low-cost synthesis process, and easy regeneration. Copyright © 2013 Elsevier Ltd. All rights reserved.

Intensity of adjuvant chemotherapy regimens and grade III-V toxicities among elderly stage III colon cancer patients.

Science.gov (United States)

van Erning, F N; Razenberg, L G E M; Lemmens, V E P P; Creemers, G J; Pruijt, J F M; Maas, H A A M; Janssen-Heijnen, M L G

2016-07-01

The aim of this study was to provide insight in the use, intensity and toxicity of therapy with capecitabine and oxaliplatin (CAPOX) and capecitabine monotherapy (CapMono) among elderly stage III colon cancer patients treated in everyday clinical practice. Data from the Netherlands Cancer Registry were used. All stage III colon cancer patients aged ≥70 years diagnosed in the southeastern part between 2005 and 2012 and treated with CAPOX or CapMono were included. Differences in completion of all planned cycles, cumulative dosages and toxicity between both regimens were evaluated. One hundred ninety-three patients received CAPOX and 164 patients received CapMono; 33% (n = 63) of the patients receiving CAPOX completed all planned cycles of both agents, whereas 55% (n = 90) of the patients receiving CapMono completed all planned cycles (P characteristics, CapMono was associated with a lower odds of developing grade III-V toxicity than CAPOX (odds ratio 0.54, 95% confidence interval 0.33-0.89). For patients treated with CAPOX, the most common toxicities were gastrointestinal (29%), haematological (14%), neurological (11%) and other toxicity (13%). For patients treated with CapMono, dermatological (17%), gastrointestinal (13%) and other toxicity (11%) were the most common. CAPOX is associated with significantly more grade III-V toxicities than CapMono, which had a pronounced impact on the cumulative dosage received and completion of all planned cycles. In this light, CapMono seems preferable over CAPOX. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-quality heat flow determination from the crystalline basement of the south-east margin of North China Craton

Science.gov (United States)

Jiang, Guangzheng; Tang, Xiaoyin; Rao, Song; Gao, Peng; Zhang, Linyou; Zhao, Ping; Hu, Shengbiao

2016-03-01

Very few of heat flow data have come from the crystalline basement in the North China Craton but rather from boreholes in the sedimentary cover of oil-gas basins. Explorations for hot dry rock (HDR) geothermal resources and porphyry gold deposits in eastern China offer now valuable opportunities to study the terrestrial heat flow in the crystalline basement. In this study, we obtained continuous temperature logs from two boreholes (the LZ borehole with a depth of 3471 m and the DR borehole with a depth of 2179 m) located in the south-east margin of the North China Craton. The boreholes have experienced long shut-in times (442 days and 261 days for the LZ borehole and DR borehole, respectively); thus, it can be expected that the temperature conditions have re-equilibrated after drilling and drill-mud circulation. Rock thermal conductivity and radiogenic heat production were measured for 68 crystalline rock samples from these two boreholes. The measured heat-flow density was determined to be 71.8 ± 2.3 mW m-2 (for the LZ borehole) and 91.5 ± 1.2 mW m-2 (for the DR borehole). The heat flow for the LZ borehole is close to the value of 75 mW m-2 determined in the Chinese Continental Scientific Drilling main hole (CCSD MH), both being in the Sulu-Dabie orogenic belt and thus able to verify each other. The value for the DR borehole is higher than the above two values, which supports former high heat-flow values determined in the Bohai Bay Basin.

High-quality EuO thin films the easy way via topotactic transformation

Science.gov (United States)

Mairoser, Thomas; Mundy, Julia A.; Melville, Alexander; Hodash, Daniel; Cueva, Paul; Held, Rainer; Glavic, Artur; Schubert, Jürgen; Muller, David A.; Schlom, Darrell G.; Schmehl, Andreas

2015-07-01

Epitaxy is widely employed to create highly oriented crystalline films. A less appreciated, but nonetheless powerful means of creating such films is via topotactic transformation, in which a chemical reaction transforms a single crystal of one phase into a single crystal of a different phase, which inherits its orientation from the original crystal. Topotactic reactions may be applied to epitactic films to substitute, add or remove ions to yield epitactic films of different phases. Here we exploit a topotactic reduction reaction to provide a non-ultra-high vacuum (UHV) means of growing highly oriented single crystalline thin films of the easily over-oxidized half-metallic semiconductor europium monoxide (EuO) with a perfection rivalling that of the best films of the same material grown by molecular-beam epitaxy or UHV pulsed-laser deposition. As the technique only requires high-vacuum deposition equipment, it has the potential to drastically improve the accessibility of high-quality single crystalline films of EuO as well as other difficult-to-synthesize compounds.

Determination of As(III) and As(V) by Flow Injection-Hydride Generation-Atomic Absorption Spectrometry via On-line Reduction of As(V) by KI

DEFF Research Database (Denmark)

Nielsen, Steffen; Hansen, Elo Harald

1997-01-01

A volume-based flow injection (FI) procedure is described for the determination and speciation of trace inorganic arsenic, As(III) and As(V), via hydride generation-atomic absorption spectrometry (HG-AAS) of As(III). The determination of total arsenic is obtained by on-line reduction of As(V) to As...

Spontaneous Synthesis of Highly Crystalline TiO2 Compact/Mesoporous Stacked Films by a Low-Temperature Steam-Annealing Method for Efficient Perovskite Solar Cells.

Science.gov (United States)

Sanehira, Yoshitaka; Numata, Youhei; Ikegami, Masashi; Miyasaka, Tsutomu

2018-05-23

Highly crystalline TiO 2 nanostructured films were synthesized by a simple steam treatment of a TiCl 4 precursor film under a saturated water vapor atmosphere at 125 °C, here referred to as the steam-annealing method. In a single TiO 2 film preparation step, a bilayer structure comprising a compact bottom layer and a mesoporous surface layer was formed. The mesoporous layer was occupied by bipyramidal nanoparticles, with a composite phase of anatase and brookite crystals. Despite the low-temperature treatment process, the crystallinity of the TiO 2 film was high, comparable with that of the TiO 2 film sintered at 500 °C. The compact double-layered TiO 2 film was applied to perovskite solar cells (PSCs) as an electron-collecting layer. The PSC exhibited a maximum power conversion efficiency (PCE) of 18.9% with an open-circuit voltage ( V OC ) of 1.15 V. The PCE and V OC were higher than those of PSCs using a TiO 2 film formed by 500 °C sintering.

Evaluation of Drug Quality (III): Determination of Ciprofloxacin ...

African Journals Online (AJOL)

user

Evaluation of Drug Quality (III): Determination of Ciprofloxacin Hydrochloride ... two methods were interpreted in terms of differences in sensitivities of the methods. It was ..... Agency for Food, Drug Administration and. Control ... regulatory standards and specified identity. Therefore drug analysis requires that drugs meet their.

The glycomic effect of N-acetylglucosaminyltransferase III overexpression in metastatic melanoma cells. GnT-III modifies highly branched N-glycans.

Science.gov (United States)

Link-Lenczowski, Paweł; Bubka, Monika; Balog, Crina I A; Koeleman, Carolien A M; Butters, Terry D; Wuhrer, Manfred; Lityńska, Anna

2018-04-01

N-acetylglucosaminyltransferase III (GnT-III) is known to catalyze N-glycan "bisection" and thereby modulate the formation of highly branched complex structures within the Golgi apparatus. While active, it inhibits the action of other GlcNAc transferases such as GnT-IV and GnT-V. Moreover, GnT-III is considered as an inhibitor of the metastatic potential of cancer cells both in vitro and in vivo. However, the effects of GnT-III may be more diverse and depend on the cellular context. We describe the detailed glycomic analysis of the effect of GnT-III overexpression in WM266-4-GnT-III metastatic melanoma cells. We used MALDI-TOF and ESI-ion-trap-MS/MS together with HILIC-HPLC of 2-AA labeled N-glycans to study the N-glycome of membrane-attached and secreted proteins. We found that the overexpression of GnT-III in melanoma leads to the modification of a broad range of N-glycan types by the introduction of the "bisecting" GlcNAc residue with highly branched complex structures among them. The presence of these unusual complex N-glycans resulted in stronger interactions of cellular glycoproteins with the PHA-L. Based on the data presented here we conclude that elevated activity of GnT-III in cancer cells does not necessarily lead to a total abrogation of the formation of highly branched glycans. In addition, the modification of pre-existing N-glycans by the introduction of "bisecting" GlcNAc can modulate their capacity to interact with carbohydrate-binding proteins such as plant lectins. Our results suggest further studies on the biological function of "bisected" oligosaccharides in cancer cell biology and their interactions with carbohydrate-binding proteins.

Ion Implantation in III-V Compound Semiconductors

Science.gov (United States)

1984-09-01

340 keV H + -0 Ga P  O UES-723-292 !:• (H o>ray *P-K X - rayO Ga-K X -ray iii! RBS * ..I -iO.. 0 10I to1. 01 • .0 -. I0 1 LI =i, O I 0 01 0.J 10...Identity by blo ," pume) Ion Implantation, GaAs, Hall effect, electrical resistivity, Rutherford Backscattering (RBS), channeling, Proton induced x -ray...Mebility (jH) upon Aiinealing Temperature (TA) for 1 X 101 /cm• Dose Samples of GaAs:Mg with Three Different Capping Methods 33 p 14 Dependence of Surface

Neutron transmission through crystalline Fe

International Nuclear Information System (INIS)

Adib, M.; Habib, N.; Kilany, M.; El-Mesiry, M.S.

2004-01-01

The neutron transmission through crystalline Fe has been calculated for neutron energies in the range 10 4 < E<10 eV using an additive formula. The formula permits calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-section as a function of temperature and crystalline form. The obtained agreement between the calculated values and available experimental ones justifies the applicability of the used formula. A feasibility study on using poly-crystalline Fe as a cold neutron filter and a large Fe single crystal as a thermal one is given

Concomitant glenohumeral pathologies associated with acute and chronic grade III and grade V acromioclavicular joint injuries.

Science.gov (United States)

Jensen, Gunnar; Millett, Peter J; Tahal, Dimitri S; Al Ibadi, Mireille; Lill, Helmut; Katthagen, Jan Christoph

2017-08-01

The purpose of this study was to identify the risk of concomitant glenohumeral pathologies with acromioclavicular joint injuries grade III and V. Patients who underwent arthroscopically-assisted stabilization of acromioclavicular joint injuries grade III or grade V between 01/2007 and 12/2015 were identified in the patient databases of two surgical centres. Gender, age at index surgery, grade of acromioclavicular joint injury (Rockwood III or Rockwood V), and duration between injury and index surgery (classified as acute or chronic) were of interest. Concomitant glenohumeral pathologies were noted and their treatment was classified as debridement or reconstructive procedure. A total of 376 patients (336 male, 40 female) were included. Mean age at time of arthroscopic acromioclavicular joint reconstruction surgery was 42.1 ± 14.0 years. Overall, 201 patients (53%) had one or more concomitant glenohumeral pathologies. Lesions of the biceps tendon complex and rotator cuff were the most common. Forty-five patients (12.0%) had concomitant glenohumeral pathologies that required an additional repair. The remaining 156 patients (41.5%) received a debridement of their concomitant pathologies. Rockwood grade V compared to Rockwood grade III (p = 0.013; odds ratio 1.7), and chronic compared to acute injury were significantly associated with having a concomitant glenohumeral pathology (p = 0.019; odds ratio 1.7). The probability of having a concomitant glenohumeral pathology was also significantly associated with increasing age (p acromioclavicular joint injury of either grade III or V. Twenty-two percent of these patients with concomitant glenohumeral pathologies received an additional dedicated repair procedure. Although a significant difference in occurrence of concomitant glenohumeral pathologies was seen between Rockwood grades III and V, and between acute and chronic lesions, increasing age was identified as the most dominant predictor. Level IV, case series.

Solution-Processible Crystalline NiO Nanoparticles for High-Performance Planar Perovskite Photovoltaic Cells.

Science.gov (United States)

Kwon, Uisik; Kim, Bong-Gi; Nguyen, Duc Cuong; Park, Jong-Hyeon; Ha, Na Young; Kim, Seung-Joo; Ko, Seung Hwan; Lee, Soonil; Lee, Daeho; Park, Hui Joon

2016-07-28

In this work, we report on solution-based p-i-n-type planar-structured CH3NH3PbI3 perovskite photovoltaic (PV) cells, in which precrystallized NiO nanoparticles (NPs) without post-treatment are used to form a hole transport layer (HTL). X-ray diffraction and high-resolution transmission electron microscopy showed the crystallinity of the NPs, and atomic force microscopy and scanning electron microscopy confirmed the uniform surfaces of the resultant NiO thin film and the subsequent perovskite photoactive layer. Compared to the conventional poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) HTL, the NiO HTL had excellent energy-level alignment with that of CH3NH3PbI3 and improved electron-blocking capability, as analyzed by photoelectron spectroscopy and diode modeling, resulting in Voc ~0.13 V higher than conventional PSS-based devices. Consequently, a power conversion efficiency (PCE) of 15.4% with a high fill factor (FF, 0.74), short-circuit current density (Jsc, 20.2 mA·cm(-2)), and open circuit voltage (Voc, 1.04 V) having negligible hysteresis and superior air stability has been achieved.

Three-Dimensional Hetero-Integration of Faceted GaN on Si Pillars for Efficient Light Energy Conversion Devices.

Science.gov (United States)

Kim, Dong Rip; Lee, Chi Hwan; Cho, In Sun; Jang, Hanmin; Jeon, Min Soo; Zheng, Xiaolin

2017-07-25

An important pathway for cost-effective light energy conversion devices, such as solar cells and light emitting diodes, is to integrate III-V (e.g., GaN) materials on Si substrates. Such integration first necessitates growth of high crystalline III-V materials on Si, which has been the focus of many studies. However, the integration also requires that the final III-V/Si structure has a high light energy conversion efficiency. To accomplish these twin goals, we use single-crystalline microsized Si pillars as a seed layer to first grow faceted Si structures, which are then used for the heteroepitaxial growth of faceted GaN films. These faceted GaN films on Si have high crystallinity, and their threading dislocation density is similar to that of GaN grown on sapphire. In addition, the final faceted GaN/Si structure has great light absorption and extraction characteristics, leading to improved performance for GaN-on-Si light energy conversion devices.

Electromagnetic processes in strong crystalline fields

CERN Multimedia

2007-01-01

We propose a number of new investigations on aspects of radiation from high energy electron and positron beams (10-300 GeV) in single crystals and amorphous targets. The common heading is radiation emission by electrons and positrons in strong electromagnetic fields, but as the setup is quite versatile, other related phenomena in radiation emission can be studied as well. The intent is to clarify the role of a number of important aspects of radiation in strong fields as e.g. observed in crystals. We propose to measure trident 'Klein-like' production in strong crystalline fields, 'crystalline undulator' radiation, 'sandwich' target phenomena, LPM suppression of pair production as well as axial and planar effects in contributions of spin to the radiation.

Effect of calcium on adsorptive removal of As(III) and As(V) by iron oxide-based adsorbents

KAUST Repository

Uwamariya, V.; Petruševski, Branislav; Lens, Piet Nl L; Amy, Gary L.

2014-01-01

for filter columns with IOCS and GFH, respectively. The adsorption of As(III) and As(V) onto GFH follows a second-order reaction, with and without addition of calcium. The adsorption of As(III) and As(V) onto IOCS follows a first-order reaction without

Ripple structures on surfaces and underlying crystalline layers in ion beam irradiated Si wafers

Energy Technology Data Exchange (ETDEWEB)

Grenzer, J.; Muecklich, A. [Forschungszentrum Rossendorf, Institut fuer Ionenstrahlphysik und Materialforschung, Dresden (Germany); Biermanns, A.; Grigorian, S.A.; Pietsch, U. [Institute of Physics, University of Siegen (Germany)

2009-08-15

We report on the formation of ion beam induced ripples in Si(001) wafers when bombarded with Ar+ ions at an energy of 60 keV. A set of samples varying incidence and azimuthal angles of the ion beam with respect to the crystalline surface orientation was studied by two complementary near surface sensitive techniques, namely atomic force microscopy and depth-resolved X-ray grazing incidence diffraction (GID). Additionally, cross-section TEM investigations were carried out. The ripple-like structures are formed at the sample surface as well as at the buried amorphous-crystalline interface. Best quality of the ripple pattern was found when the irradiating ion beam was aligned parallel to the (111) planes. The quality decreases rapidly if the direction of the ion beam deviates from (111). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Coherent-potential approximation for the lattice vibrations of mixed III-V crystals

International Nuclear Information System (INIS)

Kleinert, P.

1984-01-01

The coherent-potential approximation (CPA) is applied to the lattice dynamics of some III-V mixed crystals. The calculations are based on an eleven-parameter rigid-ion model (RIM 11). Explicit results are reported for the one-mode system In/sub 1-c/Ga/sub c/P and the two mixed-mode crystals In/sub 1-c/Ga/sub c/Sb and GaSb/sub 1-c/As/sub c/. Both, the reflectivity spectra and the composition dependence of vibrations at the GAMMA and X points are compared with existing experimental data. Force-constant changes are considered by the virtual-crystal approximation (VCA). The CPA theory is uniquely successful for III-V mixed-mode systems, which appear to switch from one-mode to two-mode behaviour. (author)

Growth and characterization of manganese doped III-V heterostructures; Herstellung und Charakterisierung von Mangan dotierten III-V Halbleiterheterostrukturen

Energy Technology Data Exchange (ETDEWEB)

Wurstbauer, Ursula

2008-04-15

Subject of this thesis is the growth of III-V heterostructures doped with manganese by means of molecular beam epitaxy (MBE). The characterization was done primarily by magnetotransport measurements in the temperature range from 300 K to 20 mK and fields up to 19 T. Two different kind of Mn doped materials, ferromagnetic GaMnAs layers and Mn modulation doped magnetic two dimensional hole systems were studied. The first part focuses on the enhancement of the electric and magnetic properties of ferromagnetic properties and the integration of GaMnAs layers in more sophisticated heterostructures. Therefore, the crystal quality and the influence of the buffer layer beneath the magnetic layer are crucial. The MBE-growth of ferromagnetic GaMnAs layers on (001), (311)A and (311)A was successfully achieved with present values of the Curie-temperature (TC). Additionally, the growth of ferromagnetic GaMnAs layers on nonpolar (110) substrates and on cleaved [110] edges was established. An application of the latter was the investigation of magnetic bipolar junctions. Magnetic two dimensional hole gases (M2DHG) has been realized by the use of In0.75Al0.25As/In0.75Ga0.25As/InAs quantum well (QW) structures. It is necessary to grow a buffer layer for strain relaxation due to the lattice mismatch by gradually increasing the In mole fraction. Magnetotransport measurements were carried out on Si doped two-dimensional electron gases (2DEG) and on Mn doped M2DHGs. From magnetotransport measurements on the M2DHGs we see some interesting features, in particular in the mK region. From the 2DEGs and all non inverted doped M2DEGs weak localization and weak antilocalization effects can be observed in the low field region. Whereas all M2DHGs with an inverted doping layer show strong localization effects and a metal insulator transition dependent on the applied magnetic field perpendicular to the QW. In the high field region Shubnikov-de-Haas oscillations in the longitudinal resistance and

Band structure effects on resonant tunneling in III-V quantum wells versus two-dimensional vertical heterostructures

Energy Technology Data Exchange (ETDEWEB)

Campbell, Philip M., E-mail: philip.campbell@gatech.edu [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Electronic Systems Laboratory, Georgia Tech Research Institute, Atlanta, Georgia 30332 (United States); Tarasov, Alexey; Joiner, Corey A.; Vogel, Eric M. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Ready, W. Jud [Electronic Systems Laboratory, Georgia Tech Research Institute, Atlanta, Georgia 30332 (United States)

2016-01-14

Since the invention of the Esaki diode, resonant tunneling devices have been of interest for applications including multi-valued logic and communication systems. These devices are characterized by the presence of negative differential resistance in the current-voltage characteristic, resulting from lateral momentum conservation during the tunneling process. While a large amount of research has focused on III-V material systems, such as the GaAs/AlGaAs system, for resonant tunneling devices, poor device performance and device-to-device variability have limited widespread adoption. Recently, the symmetric field-effect transistor (symFET) was proposed as a resonant tunneling device incorporating symmetric 2-D materials, such as transition metal dichalcogenides (TMDs), separated by an interlayer barrier, such as hexagonal boron-nitride. The achievable peak-to-valley ratio for TMD symFETs has been predicted to be higher than has been observed for III-V resonant tunneling devices. This work examines the effect that band structure differences between III-V devices and TMDs has on device performance. It is shown that tunneling between the quantized subbands in III-V devices increases the valley current and decreases device performance, while the interlayer barrier height has a negligible impact on performance for barrier heights greater than approximately 0.5 eV.

Band structure effects on resonant tunneling in III-V quantum wells versus two-dimensional vertical heterostructures

Science.gov (United States)

Campbell, Philip M.; Tarasov, Alexey; Joiner, Corey A.; Ready, W. Jud; Vogel, Eric M.

2016-01-01

Since the invention of the Esaki diode, resonant tunneling devices have been of interest for applications including multi-valued logic and communication systems. These devices are characterized by the presence of negative differential resistance in the current-voltage characteristic, resulting from lateral momentum conservation during the tunneling process. While a large amount of research has focused on III-V material systems, such as the GaAs/AlGaAs system, for resonant tunneling devices, poor device performance and device-to-device variability have limited widespread adoption. Recently, the symmetric field-effect transistor (symFET) was proposed as a resonant tunneling device incorporating symmetric 2-D materials, such as transition metal dichalcogenides (TMDs), separated by an interlayer barrier, such as hexagonal boron-nitride. The achievable peak-to-valley ratio for TMD symFETs has been predicted to be higher than has been observed for III-V resonant tunneling devices. This work examines the effect that band structure differences between III-V devices and TMDs has on device performance. It is shown that tunneling between the quantized subbands in III-V devices increases the valley current and decreases device performance, while the interlayer barrier height has a negligible impact on performance for barrier heights greater than approximately 0.5 eV.

Efficient n-type doping of zinc-blende III-V semiconductor nanowires

Science.gov (United States)

Besteiro, Lucas V.; Tortajada, Luis; Souto, J.; Gallego, L. J.; Chelikowsky, James R.; Alemany, M. M. G.

2014-03-01

We demonstrate that it is preferable to dope III-V semiconductor nanowires by n-type anion substitution as opposed to cation substitution. Specifically, we show the dopability of zinc-blende nanowires is more efficient when the dopants are placed at the anion site as quantified by formation energies and the stabilization of DX-like defect centers. The comparison with previous work on n - type III-V semiconductor nanocrystals also allows to determine the role of dimensionality and quantum confinement on doping characteristics of materials. Our results are based on first-principles calculations of InP nanowires by using the PARSEC code. Work supported by the Spanish MICINN (FIS2012-33126) and Xunta de Galicia (GPC2013-043) in conjunction with FEDER. JRC acknowledges support from DoE (DE-FG02-06ER46286 and DESC0008877). Computational support was provided in part by CESGA.

Speciation of As(III) and As(V) in water and sediment using reverse-phase ion-pair high-performance liquid chromatography-neutron activation analysis (HPLC-NAA).

Science.gov (United States)

Tulasi, Delali; Adotey, Dennis; Affum, Andrews; Carboo, Derick; Serfor-Armah, Yaw

2013-10-01

Total As content and the As species distribution in water and sediments from the Kwabrafo stream, a major water body draining the Obuasi gold mining community in southwestern Ghana, have been investigated. Total As content was determined by instrumental neutron activation analysis (INAA). Ion-pair reverse phase high-performance liquid chromatography-neutron activation analysis (HPLC-NAA) was used for speciation of As species. Solid phase extraction with phosphate buffer was used to extract soluble As species from lyophilized sediment. The mass balance after phosphate extraction of soluble As species in sediment varied from 89 to 96 %. Compositionally appropriate reference material International Atomic Energy Agency (IAEA)-Lake Sediment (SL)-1 was used to check the validity of INAA method for total As determination. The measured values are in good agreement with the IAEA recommended value and also within the 95 % confidence interval. The accuracy of the measurement in terms of relative deviation from the IAEA recommended value was ±0.83 %. "In-house" prepared As(III) and As(V) standards were used to validate the HPLC-INAA method used for the As species determination. Total As concentration in the water samples ranged from 1.15 to 9.20 mg/L. As(III) species in water varied from 0.13 to 0.7 mg/L, while As(V) species varied from 0.79 to 3.85 mg/L. Total As content in sediment ranged from 2,134 to 3,596 mg/kg dry mass. The levels of As(III) and As(V) species in the sediment ranges from 138 to 506 mg/kg dry mass and 156 to 385 mg/kg dry mass, respectively.

Crystalline-Amorphous Core−Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes

KAUST Repository

Cui, Li-Feng

2009-01-14

Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon\\'s large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline- amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li ions. We demonstrate here that these core-shell nanowires have high charge storage capacity (̃1000 mAh/g, 3 times of carbon) with ̃90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, ̃20 times of carbon at 1 h rate). © 2009 American Chemical Society.

High rate flame synthesis of highly crystalline iron oxide nanorods

International Nuclear Information System (INIS)

Merchan-Merchan, W; Taylor, A M; Saveliev, A V

2008-01-01

Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe 3 O 4 ) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks

Growth and characterisation of group-III nitride-based nanowires for devices

Energy Technology Data Exchange (ETDEWEB)

Meijers, R J

2007-08-30

One of the main goals of this thesis was to get more insight into the mechanisms driving the growth of nitride nanowires by plasma-assisted molecular beam epitaxy (PA-MBE). The influence of the group-III and group-V flux as well as the substrate temperature T{sub sub} has been studied leading to the conclusion that the III-V ratio determines the growth mode. Ga desorption limits the temperature range to grow GaN nanowires and dissociation of InN is the limiting factor for InN nanowire growth. A reduction of the surface diffusivity on polar surfaces under N-rich conditions explains the anisotropic growth. Growth kinetics of the nanowires show that there are two important contributions to the growth. The first is growth by direct impingement and its contribution is independent of the nanowire diameter. The second contribution comes from atoms, which absorb on the substrate or wire sidewalls and diffuse along the sidewalls to the top of the wire, which acts as an effective sink for the adatoms due to a reduced surface mobility on the polar top of the wires. This diffusion channel, which is enhanced at higher T{sub sub}, becomes more significant for smaller wire diameters, because its contribution scales like 1/d. Experiments with an interruption of the growth and sharp interfaces in TEM images of heterostructures show that the suggestion in literature of a droplet-mediated PA-MBE nitride growth has to be discarded. Despite a thin amorphous silicon nitride wetting layer on the substrate surface, both GaN and InN nanowires grow in the wurtzite structure and epitaxially in a one-to-one relation to the Si(111) substrate surface. There is no evidence for cubic phases. TEM images and optical studies display a high crystalline and optical quality of GaN and InN nanowires. The substrate induces some strain in the bottom part of the nanowires, especially in InN due to the lower T{sub sub} than for GaN, which is released without the formation of dislocations. Only some stacking

Heavy ion irradiation of crystalline water ice. Cosmic ray amorphisation cross-section and sputtering yield

Science.gov (United States)

Dartois, E.; Augé, B.; Boduch, P.; Brunetto, R.; Chabot, M.; Domaracka, A.; Ding, J. J.; Kamalou, O.; Lv, X. Y.; Rothard, H.; da Silveira, E. F.; Thomas, J. C.

2015-04-01

Context. Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims: We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. Methods: We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results: The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions: The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice sputtering rates compete with the UV photodesorption yields reported in the literature. The prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices. Experiments performed at the Grand Accélérateur National d'Ions Lourds (GANIL) Caen, France. Part of this work has been financed by the French INSU-CNRS programme "Physique et Chimie du Milieu Interstellaire" (PCMI) and the ANR IGLIAS.

Speciation of the immediately mobilisable As(III), As(V), MMA and DMA in river sediments by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry following ultrasonic extraction

International Nuclear Information System (INIS)

Huerga, A.; Lavilla, I.; Bendicho, C.

2005-01-01

In this work, a fast method is developed for the speciation of As(III), As(V), MMA and DMA in the immediately mobilisable fraction of river sediments (i.e. water-soluble and phosphate-exchangeable) by high performance liquid chromatography-hydride generation-atomic fluorescence detection (HPLC-HG-AFD) after extraction using focused ultrasound. The influence of relevant parameters influencing an ion-pairing chromatographic separation following isocratic elution (i.e. amount of MeOH in the mobile phase, ion pair reagent concentration, pH, flow rate) was studied. Focused ultrasound transmitted from an ultrasonic probe provided the same extractable contents as conventional extraction with no changes in the species distribution. The effect of the drying step over extraction of As species was investigated. The following drying procedures were compared: freeze-, oven-, microwave- and air-drying. No influence of the drying operation on the water-extractable fraction was observed. However, freeze- and air-drying yielded significantly higher phosphate-extractable amounts of As(III) and As(V) as compared to oven and microwaves. Detection limits for the As species were in the range 1.3-4.1 ng/g for the water-soluble fraction and 1.6-4.8 ng/g for the phosphate buffer exchangeable fraction. The method was applied to the speciation of immediately mobilisable As(III), As(V), DMA and MMA in 11 sediment samples collected along the beds of the Louro River (southern Galicia, Spain)

Fabrication of high quality GaAs-on-insulator via ion-cut of epitaxial GaAs/Ge heterostructure

Energy Technology Data Exchange (ETDEWEB)

Chang, Yongwei; Zhang, Miao [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Deng, Chuang; Men, Chuanling [School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Chen, Da [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Zhu, Lei; Yu, Wenjie; Wei, Xing [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Di, Zengfeng, E-mail: zfdi@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Xi [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2015-08-15

Highlights: • GaAs-on-insulator has been achieved by integrating of epitaxy, ion-cut and selective chemical etching. • Superior to the direct ion-cut of bulk GaAs layer with the H implantation fluence 2.0 × 10{sup 17} cm{sup −2}, the fabrication of GaAs-on-insulator by the transfer of GaAs/Ge heterostructure only needs H implantation fluence as low as 0.8 × 10{sup 17} cm{sup −2}. • The crystalline quality of the top GaAs layer of the final GaAs-on-insulator wafer is not affected by the implantation process and comparable to the as-grown status. - Abstract: Due to the extraordinary electron mobility, III–V compounds are considered as the ideal candidate channel materials for future electronic devices. In this study, a novel approach for the fabrication of high-crystalline quality GaAs-on-insulator has been proposed by integrating of ion-cut and selective chemical etching. GaAs layer with good crystalline quality has been epitaxially grown on Ge by molecular beam epitaxy (MBE). With H implantation and wafer bonding process, the GaAs/Ge heterostructure is transferred onto silicon dioxide wafer after the proper thermal treatment. Superior to the direct ion-cut of GaAs layer, which requires the H implantation fluence as high as 2.0 × 10{sup 17} cm{sup −2}, the transfer of GaAs/Ge heterostructure in the present study only needs the implantation of 0.8 × 10{sup 17} cm{sup −2} H ions. GaAs-on-insulator structure was successfully achieved by the selective chemical etching of defective Ge layer using SF{sub 6} plasma. As the GaAs/Ge heterostructure can be easily epitaxy grown on silicon platform, the proposed approach for GaAs-on-insulator manufacturing is rather compatible with mature Si integrated circuits (ICs) technology and thus can be integrated to push the microelectronic technology to post-Si era.

Fabrication of high quality GaAs-on-insulator via ion-cut of epitaxial GaAs/Ge heterostructure

International Nuclear Information System (INIS)

Chang, Yongwei; Zhang, Miao; Deng, Chuang; Men, Chuanling; Chen, Da; Zhu, Lei; Yu, Wenjie; Wei, Xing; Di, Zengfeng; Wang, Xi

2015-01-01

Highlights: • GaAs-on-insulator has been achieved by integrating of epitaxy, ion-cut and selective chemical etching. • Superior to the direct ion-cut of bulk GaAs layer with the H implantation fluence 2.0 × 10 17 cm −2 , the fabrication of GaAs-on-insulator by the transfer of GaAs/Ge heterostructure only needs H implantation fluence as low as 0.8 × 10 17 cm −2 . • The crystalline quality of the top GaAs layer of the final GaAs-on-insulator wafer is not affected by the implantation process and comparable to the as-grown status. - Abstract: Due to the extraordinary electron mobility, III–V compounds are considered as the ideal candidate channel materials for future electronic devices. In this study, a novel approach for the fabrication of high-crystalline quality GaAs-on-insulator has been proposed by integrating of ion-cut and selective chemical etching. GaAs layer with good crystalline quality has been epitaxially grown on Ge by molecular beam epitaxy (MBE). With H implantation and wafer bonding process, the GaAs/Ge heterostructure is transferred onto silicon dioxide wafer after the proper thermal treatment. Superior to the direct ion-cut of GaAs layer, which requires the H implantation fluence as high as 2.0 × 10 17 cm −2 , the transfer of GaAs/Ge heterostructure in the present study only needs the implantation of 0.8 × 10 17 cm −2 H ions. GaAs-on-insulator structure was successfully achieved by the selective chemical etching of defective Ge layer using SF 6 plasma. As the GaAs/Ge heterostructure can be easily epitaxy grown on silicon platform, the proposed approach for GaAs-on-insulator manufacturing is rather compatible with mature Si integrated circuits (ICs) technology and thus can be integrated to push the microelectronic technology to post-Si era

Heterogeneous Silicon III-V Mode-Locked Lasers

Science.gov (United States)

Davenport, Michael Loehrlein

Mode-locked lasers are useful for a variety of applications, such as sensing, telecommunication, and surgical instruments. This work focuses on integrated-circuit mode-locked lasers: those that combine multiple optical and electronic functions and are manufactured together on a single chip. While this allows production at high volume and lower cost, the true potential of integration is to open applications for mode-locked laser diodes where solid state lasers cannot fit, either due to size and power consumption constraints, or where small optical or electrical paths are needed for high bandwidth. Unfortunately, most high power and highly stable mode-locked laser diode demonstrations in scientific literature are based on the Fabry-Perot resonator design, with cleaved mirrors, and are unsuitable for use in integrated circuits because of the difficulty of producing integrated Fabry-Perot cavities. We use silicon photonics and heterogeneous integration with III-V gain material to produce the most powerful and lowest noise fully integrated mode-locked laser diode in the 20 GHz frequency range. If low noise and high peak power are required, it is arguably the best performing fully integrated mode-locked laser ever demonstrated. We present the design methodology and experimental pathway to realize a fully integrated mode-locked laser diode. The construction of the device, beginning with the selection of an integration platform, and proceeding through the fabrication process to final optimization, is presented in detail. The dependence of mode-locked laser performance on a wide variety of design parameters is presented. Applications for integrated circuit mode-locked lasers are also discussed, as well as proposed methods for using integration to improve mode-locking performance to beyond the current state of the art.

III-V-on-Silicon Photonic Integrated Circuits for Spectroscopic Sensing in the 2-4 μm Wavelength Range.

Science.gov (United States)

Wang, Ruijun; Vasiliev, Anton; Muneeb, Muhammad; Malik, Aditya; Sprengel, Stephan; Boehm, Gerhard; Amann, Markus-Christian; Šimonytė, Ieva; Vizbaras, Augustinas; Vizbaras, Kristijonas; Baets, Roel; Roelkens, Gunther

2017-08-04

The availability of silicon photonic integrated circuits (ICs) in the 2-4 μm wavelength range enables miniature optical sensors for trace gas and bio-molecule detection. In this paper, we review our recent work on III-V-on-silicon waveguide circuits for spectroscopic sensing in this wavelength range. We first present results on the heterogeneous integration of 2.3 μm wavelength III-V laser sources and photodetectors on silicon photonic ICs for fully integrated optical sensors. Then a compact 2 μm wavelength widely tunable external cavity laser using a silicon photonic IC for the wavelength selective feedback is shown. High-performance silicon arrayed waveguide grating spectrometers are also presented. Further we show an on-chip photothermal transducer using a suspended silicon-on-insulator microring resonator used for mid-infrared photothermal spectroscopy.

Hydrothermal Synthesis and Biocompatibility Study of Highly Crystalline Carbonated Hydroxyapatite Nanorods

Science.gov (United States)

Xue, Caibao; Chen, Yingzhi; Huang, Yongzhuo; Zhu, Peizhi

2015-08-01

Highly crystalline carbonated hydroxyapatite (CHA) nanorods with different carbonate contents were synthesized by a novel hydrothermal method. The crystallinity and chemical structure of synthesized nanorods were studied by Fourier transform infrared spectroscopy (FTIR), X-ray photo-electronic spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The biocompatibility of synthesized CHA nanorods was evaluated by cell viability and alkaline phosphatase (ALP) activity of MG-63 cell line. The biocompatibility evaluation results show that these CHA nanorods are biologically active apatites and potentially promising bone-substitute biomaterials for orthopedic application.

Managed aquifer recharge in weathered crystalline basement aquifers in India: Monitoring of the effect of tank infiltration on water quality over several monsoon events

Science.gov (United States)

Alazard, Marina; Boisson, Alexandre; Maréchal, Jean-Christophe; Dewandel, Benoît; Perrin, Jérôme; Pettenati, Marie; Picot-Colbeaux, Géraldine; Ahmed, Shakeel; Thiéry, Dominique; Kloppmann, Wolfram

2015-04-01

Managed aquifer recharge (MAR) structures like percolation tanks are considered by the Indian national and regional governments as major option for tackling declining groundwater levels due to overexploitation for irrigation purposes (Boisson et al., 2014). Their main purpose is to restore groundwater availability under strong climatic and anthropogenic pressure. Furthermore, MAR-induced dilution with fresh surface water is generally expected to improve groundwater quality with respect to both anthropogenic and geogenic contaminants (total mineralisation, nitrates, chlorides, sulphates and fluoride contents). The impact of a percolation tank on groundwater quality was investigated in a context that is typical for hydro-climatic and geological settings in southern and eastern India: fractured crystalline basement aquifers overlain by a weathering zone under semi-arid climate. Water level data and geochemical indicators (stable isotopes and major ions) were monitored for both groundwater and surface water, over several successive monsoon events. In case of high to very high water levels, the groundwater quality is globally improved. However, in a few cases, the quality of the groundwater can be negatively impacted due to leaching of salts under the tank, particularly during the first rain events of the monsoon. Geogenic fluoride contents in groundwater, induced by water-rock interaction and enhanced by recycling of agricultural return flow under paddy fields, is found to be relatively stable over the year. This finding points out that the underlying processes, mainly dissolution of F-bearing phases like fluorapatites combined with Ca/Na cation exchange and calcite precipitation, both limiting the possibility of F-removal via fluorite precipitation (Pettenati et al., 2013, 2014), are not impacted by the hydrological conditions. This work highlights the complexity of the recharge processes in crystalline aquifers, enhanced by the variability of hydrological conditions

Uric acid levels in plasma and urine in rats chronically exposed to inorganic As (III) and As(V).

Science.gov (United States)

Jauge, P; Del-Razo, L M

1985-07-01

The effect of inorganic arsenic (III) and arsenic (V) on renal excretion and plasma levels of uric acid was examined in rats. Oral administration of 1200 micrograms As/kg/day for 6 weeks diminished uric acid levels in plasma by 67.1% and 26.5% of control after the administration of As(III) and As(V), respectively. Renal excretion of uric acid was significantly reduced during the first 3 weeks following As (III) administration, with a subsequent increase to approach control values at the end of the treatment. When As(V) was administered, the diminution in renal excretion was significant at 6 weeks.

Minimalistic Liquid-Assisted Route to Highly Crystalline α-Zirconium Phosphate.

Science.gov (United States)

Cheng, Yu; Wang, Xiaodong Tony; Jaenicke, Stephan; Chuah, Gaik-Khuan

2017-08-24

Zirconium phosphates have potential applications in areas of ion exchange, catalysis, photochemistry, and biotechnology. However, synthesis methodologies to form crystalline α-zirconium phosphate (Zr(HPO 4 ) 2 ⋅H 2 O) typically involve the use of excess phosphoric acid, addition of HF or oxalic acid and long reflux times or hydrothermal conditions. A minimalistic sustainable route to its synthesis has been developed by using only zirconium oxychloride and concentrated phosphoric acid to form highly crystalline α-zirconium phosphate within hours. The morphology can be changed from platelets to rod-shaped particles by fluoride addition. By varying the temperature and time, α-zirconium phosphate with particle sizes from nanometers to microns can be obtained. Key features of this minimal solvent synthesis are the excellent yields obtained with high atom economy under mild conditions and ease of scalability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Economically attractive route for the preparation of high quality magnetic nanoparticles by the thermal decomposition of iron(III) acetylacetonate.

Science.gov (United States)

Effenberger, Fernando B; Couto, Ricardo A; Kiyohara, Pedro K; Machado, Giovanna; Masunaga, Sueli H; Jardim, Renato F; Rossi, Liane M

2017-03-17

The thermal decomposition (TD) methods are among the most successful in obtaining magnetic nanoparticles with a high degree of control of size and narrow particle size distribution. Here we investigated the TD of iron(III) acetylacetonate in the presence of oleic acid, oleylamine, and a series of alcohols in order to disclose their role and also investigate economically attractive alternatives for the synthesis of iron oxide nanoparticles without compromising their size and shape control. We have found that some affordable and reasonably less priced alcohols, such as 1,2-octanediol and cyclohexanol, may replace the commonly used and expensive 1,2-hexadecanediol, providing an economically attractive route for the synthesis of high quality magnetic nanoparticles. The relative cost for the preparation of Fe 3 O 4 NPs is reduced to only 21% and 9% of the original cost when using 1,2-octanediol and cyclohexanol, respectively.

Structure and stability of hexa-aqua V(III) cations in vanadium redox flow battery electrolytes.

Science.gov (United States)

Vijayakumar, M; Li, Liyu; Nie, Zimin; Yang, Zhenguo; Hu, JianZhi

2012-08-07

The vanadium(III) cation structure in mixed acid based electrolyte solution from vanadium redox flow batteries is studied by (17)O and (35/37)Cl nuclear magnetic resonance (NMR) spectroscopy, electronic spectroscopy and density functional theory (DFT) based computational modelling. Both computational and experimental results reveal that the V(III) species can complex with counter anions (sulfate/chlorine) depending on the composition of its solvation sphere. By analyzing the powder precipitate it was found that the formation of sulfate complexed V(III) species is the crucial process in the precipitation reaction. The precipitation occurs through nucleation of neutral species formed through deprotonation and ion-pair formation process. However, the powder precipitate shows a multiphase nature which warrants multiple reaction pathways for precipitation reaction.

Improved crystalline quality of AlN epitaxial layer on sapphire by introducing TMGa pulse flow into the nucleation stage

Science.gov (United States)

Wu, Hualong; Wang, Hailong; Chen, Yingda; Zhang, Lingxia; Chen, Zimin; Wu, Zhisheng; Wang, Gang; Jiang, Hao

2018-05-01

The crystalline quality of AlN epitaxial layers on sapphire substrates was improved by introducing trimethylgallium (TMGa) pulse flow into the growth of AlN nucleation layers. It was found that the density of both screw- and edge-type threading dislocations could be significantly reduced by introducing the TMGa pulse flow. With increasing TMGa pulse flow times, the lateral correlation length (i.e. the grain size) increases and the strain in the AlN epilayers changes from tensile state to compressive state. Unstrained AlN with the least dislocations and a smooth surface was obtained by introducing 2-times TMGa pulse flow. The crystalline improvement is attributed to enhanced lateral growth and improved crystalline orientation by the TMGa pulse flow.

Structural properties of III-V zinc-blende semiconductors under pressure

International Nuclear Information System (INIS)

Froyen, S.; Cohen, M.L.

1983-01-01

The pseudopotential method within the local-density approximation is used to investigate the static and structural properties of some III-V compound semiconductors. Comparisons of calculated total energies as a function of volume and structure yield information about solid-solid phase transformations. At high pressures the results indicate that several metallic structures are lower in energy than the zinc-blende structure. From our results the compounds (AlP, AlAs, GaP, and GaAs) can be divided into two classes. In the Ga compounds, we find a pressure-induced phase transformation to either rocksalt, β-Sn, or NiAs, whereas in the Al compounds rocksalt and NiAs are stabilized with respect to β-Sn. All structures except zinc blende are metallic. We discuss the electronic structure of each phase and show how it relates to structural stability

Investigating the effect of ascorbate on the Fe(II)-catalyzed transformation of the poorly crystalline iron mineral ferrihydrite.

Science.gov (United States)

Xiao, Wei; Jones, Adele M; Collins, Richard N; Waite, T David

2018-05-09

The inorganic core of the iron storage protein, ferritin, is recognized as being analogous to the poorly crystalline iron mineral, ferrihydrite (Fh). Fh is also abundant in soils where it is central to the redox cycling of particular soil contaminants and trace elements. In geochemical circles, it is recognized that Fh can undergo Fe(II)-catalyzed transformation to form more crystalline iron minerals, vastly altering the reactivity of the iron oxide and, in some cases, the redox poise of the system. Of relevance to both geochemical and biological systems, we investigate here if the naturally occurring reducing agent, ascorbate, can effect such an Fe(II)-catalyzed transformation of Fh at 25 °C and circumneutral pH. The transformation of ferrihydrite to possible secondary Fe(III) mineralization products was quantified using Fourier transform infrared (FTIR) spectroscopy, with supporting data obtained using X-ray absorbance spectroscopy (XAS) and X-ray diffraction (XRD). Whilst the amount of Fe(II) formed in the presence of ascorbate has resulted in Fh transformation in previous studies, no transformation of Fh to more crystalline Fe(III) (oxyhydr)oxides was observed in this study. Further experiments indicated this was due to the ability of ascorbate to inhibit the formation of goethite, lepidocrocite and magnetite. The manner in which ascorbate associated with Fh was investigated using FTIR and total organic carbon (TOC) analysis. The majority of ascorbate was found to adsorb to the Fh surface under anoxic conditions but, under oxic conditions, ascorbate was initially adsorbed then became incorporated within the Fe(III) (oxyhydr)oxide structure (i.e., co-precipitated) over time. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of Er-doping on the structural and optical properties of Cd{sub 2}V{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Lozada-Morales, R.; Cid-Garcia, A.; Palomino-Merino, R. [Benemerita Universidad Autonoma de Puebla, Postgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico); Lopez-Calzada, G.; Jimenez-Sandoval, S. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Apartado Postal 1-798, Queretaro, Qro. 76001 (Mexico); Zayas, Ma.E. [Departamento de Investigacion en Fisica de la Universidad de Sonora, Edificio 3I, Blvd. Edificio 5 E, Luis Encinas s/n, Col. Centro, 83000 Hermosillo, Sonora (Mexico); Zelaya-Angel, O. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados, P.O. Box 14-740, Mexico D. F. 07360 (Mexico); Carmona-Rodriguez, J. [Instituto Tecnologico Superior de Poza Rica, Calle Luis Donaldo Colosio S/N, Col. Arroyo del Maiz, C.P. 93230, Poza Rica, Veracruz (Mexico); Rubio-Rosas, E. [Centro de Vinculacion Universitaria, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico); Portillo-Moreno, O. [Facultad de Ciencias Quimicas, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico)

2012-11-15

The melt-quenching method was used to prepare two groups of samples using CdO and V{sub 2}O{sub 5} as starting materials. Taking into account that a crystalline-amorphous phase transition would be expected for the CdO-V{sub 2}O{sub 5} system, a first batch was prepared varying the proportions of CdO and V{sub 2}O{sub 5} in the intervals 60-95 and 40-5 wt%, respectively. With the aim of investigating the effect of erbium in the phase transition and crystalline quality of the first group of samples, a second batch was fabricated with the same proportions of CdO and V{sub 2}O{sub 5}, with the addition of 5 wt% of Er(NO{sub 3})5H{sub 2}O as source of Er{sup 3+} ions. It was found that crystalline or amorphous samples could be obtained depending on the relative concentrations of CdO and V{sub 2}O{sub 5}, and that the borderline between amorphous and crystalline samples was affected by the incorporation of Er. From X-ray diffraction, it was possible to identify the formation of the ternary compound Cd{sub 2}V{sub 2}O{sub 7} in the crystalline cases. The Raman and infrared bands in these samples were in agreement with the lattice modes of Cd{sub 2}V{sub 2}O{sub 7}. Additionally, an improvement in the crystalline quality of Cd{sub 2}V{sub 2}O{sub 7} was obtained for the Er-doped samples. The effect of the local environment around the Er{sup 3+} ions on the room temperature photoluminescence was also investigated for the amorphous and crystalline samples. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Formation constants of Sm(III), Dy(III), Gd(III), Pr(III) and Nd(III) complexes of tridentate schiff base, 2-[(1H-benzimidazol-2-yl-methylene) amino] phenol

International Nuclear Information System (INIS)

Omprakash, K.L.; Chandra Pal, A.V.; Reddy, M.L.N.

1982-01-01

A new tridentate schiff base, 2- (1H-benzimidazol-2-yl-methylene)amino phenol derived from benzimididazole-2-carbo-xaldehyde and 2-aminophenol has been synthesised and characterised by spectral and analytical data. Proton-ligand formation constants of the schiff base and metal-ligand formation constants of its complexes with Sm(III), Dy(III), Gd(III), Nd(III) and Pr(III) have been determined potentiometrically in 50% (v/v) aqueous dioxane at an ionic strength of 0.1M (NaClO 4 ) and at 25deg C using the Irving-Rossotti titration technique. The order of stability constants (logβ 2 ) is found to be Sm(III)>Dy(III)>Gd(III)>Pr(III)>Nd(III). (author)

Formation constants of Sm(III), Dy(III), Gd(III), Pr(III) and Nd(III) complexes of tridentate schiff base, 2-((1H-benzimidazol-2-yl-methylene) amino) phenol

Energy Technology Data Exchange (ETDEWEB)

Omprakash, K L; Chandra Pal, A V; Reddy, M L.N. [Osmania Univ., Hyderabad (India). Dept. of Chemistry

1982-03-01

A new tridentate schiff base, 2- (1H-benzimidazol-2-yl-methylene)amino phenol derived from benzimididazole-2-carbo-xaldehyde and 2-aminophenol has been synthesised and characterised by spectral and analytical data. Proton-ligand formation constants of the schiff base and metal-ligand formation constants of its complexes with Sm(III), Dy(III), Gd(III), Nd(III) and Pr(III) have been determined potentiometrically in 50% (v/v) aqueous dioxane at an ionic strength of 0.1M (NaClO/sub 4/) and at 25deg C using the Irving-Rossotti titration technique. The order of stability constants (log..beta../sub 2/) is found to be Sm(III)>Dy(III)>Gd(III)>Pr(III)>Nd(III).

Elemental abundance analyses with DAO spectrograms: XXXII. HR 6455 (A3 III), δ Aqr (A3 V), η Lep (F2 V), and 1 Boo (A1 V)

Science.gov (United States)

Yüce, K.; Adelman, S. J.; Gulliver, A. F.; Hill, G.

2011-08-01

We examine the sharp-lined stars HR 6455 (A3 III, v sin i = 8.7 km s-1) and η Lep (F2 V, v sin i = 13.5 km s-1) as well as δ Aqr (A3 V, v sin i = 81 km s-1) and 1 Boo (A1 V, v sin i = 59 km s-1) to increase the number consistently analyzed A and F stars using high dispersion and high S/N (≥200) spectrograms obtained with CCD detectors at the long Coudé camera of the 1.22-m telescope of the Dominion Astrophysical Observatory. Such studies contribute to understanding systematic abundance differences between normal and non-magnetic main-sequence band chemically peculiar A and early F stars. LTE fine analyses of HR 6455, δ Aqr, and 1 Boo using Kurucz's ATLAS suite programs show the same general elemental abundance trends with differences in the metal richness. Light and iron-peak element abundances are generally solar or overabundant while heavy element and rare earth element abundances are overabundant. HR 6455 is an evolved Am star while δ Aqr and 1 Boo show the phenomenon to different extents. Most derived abundances of η Lep are solar. Table 3 is available at the CDS via http://cdsarc.u-strasbg.fr/cgi-bin/qcat?J/AN/332/681

Halide based MBE of crystalline metals and oxides

Energy Technology Data Exchange (ETDEWEB)

Greenlee, Jordan D.; Calley, W. Laws; Henderson, Walter; Doolittle, W. Alan [Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, Georgia (United States)

2012-02-15

A halide based growth chemistry has been demonstrated which can deliver a range of transition metals using low to moderate effusion cell temperatures (30-700 C) even for high melting point metals. Previously, growth with transition metal species required difficult to control electron beam or impurity inducing metal organic sources. Both crystalline oxide and metal films exhibiting excellent crystal quality are grown using this halide-based growth chemistry. Films are grown using a plasma assisted Molecular Beam Epitaxy (MBE) system with metal-chloride precursors. Crystalline niobium, cobalt, iron, and nickel were grown using this chemistry but the technology can be generalized to almost any metal for which a chloride precursor is available. Additionally, the oxides LiNbO{sub 3} and LiNbO{sub 2} were grown with films exhibiting X-ray diffraction (XRD) rocking curve full-widths at half maximum of 150 and 190 arcseconds respectively. LiNbO{sub 2} films demonstrate a memristive response due to the rapid movement of lithium in the layered crystal structure. The rapid movement of lithium ions in LiNbO{sub 2} memristors is characterized using impedance spectroscopy measurements. The impedance spectroscopy measurements suggest an ionic current of.1 mA for a small drive voltage of 5 mV AC or equivalently an ionic current density of {proportional_to}87 A/cm{sup 2}. This high ionic current density coupled with low charge transfer resistance of {proportional_to}16.5 {omega} and a high relaxation frequency (6.6 MHz) makes this single crystal material appealing for battery applications in addition to memristors. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Amorphization and recrystallization in MeV ion implanted InP crystals

International Nuclear Information System (INIS)

Xiong, F.; Nieh, C.W.; Jamieson, D.N.; Vreeland, T. Jr.; Tombrello, T.A.

1988-01-01

A comprehensive study of MeV- 15 N-ion-implanted InP by a variety of analytical techniques has revealed the physical processes involved in MeV ion implantation into III-V compound semiconductors as well as the influence of post-implantation annealing. It provides a coherent picture of implant distribution, structural transition, crystalline damage, and lattice strain in InP crystals induced by ion implantation and thermal annealing. The experimental results from the different measurements are summarized in this report. Mechanisms of amorphization by implantation and recrystallization through annealing in MeV-ion-implanted InP are proposed and discussed in light of the results obtained

Iron (III) oxyhydroxide in isopropyl alcohol preparation, characterization and solvothermal treatment

International Nuclear Information System (INIS)

Carvalho, E.L.C.N.; Jafelicci Junior, M.

1989-01-01

Iron (III) nitrate hydrolysis was carried out in isopropyl alcohol solution by an aqueous amonia gas stream resulting in iron (III) oxyhydroxide sol. It has been investigated in this work the solvothermal treatment of this colloidal system at 120 0 C and 24 hours. Iron (III) oxyhydroxide freshly obtained and solvothermally treated. Samples were dryed by lyophilization. Products obtained were characterized by the following techniques: spectrophotometric iron analysis by 1,10-orthophenantroline complexation method, powder X-ray diffraction, vibrational infrared spectra and differential thermal analysis. After solvothermal treatment resulting product was crystallized into hematite, while freshly iron (III) oxyhydroxide was non crystalline. Both of them are very active powder, showing high water adsorption [pt

30 CFR 57.22205 - Doors on main fans (I-A, II-A, III, and V-A mines).

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Doors on main fans (I-A, II-A, III, and V-A... main fans (I-A, II-A, III, and V-A mines). In mines ventilated by multiple main fans, each main fan... reversal through the fan. The doors shall be located so that they are not in direct line with explosive...

Understanding the vapor-liquid-solid growth and composition of ternary III-V nanowires and nanowire heterostructures

Science.gov (United States)

Dubrovskii, V. G.

2017-11-01

Based on the recent achievements in vapor-liquid-solid (VLS) synthesis, characterization and modeling of ternary III-V nanowires and axial heterostructures within such nanowires, we try to understand the major trends in their compositional evolution from a general theoretical perspective. Clearly, the VLS growth of ternary materials is much more complex than in standard vapor-solid epitaxy techniques, and even maintaining the necessary control over the composition of steady-state ternary nanowires is far from straightforward. On the other hand, VLS nanowires offer otherwise unattainable material combinations without introducing structural defects and hence are very promising for next-generation optoelectronic devices, in particular those integrated with a silicon electronic platform. In this review, we consider two main problems. First, we show how and by means of which parameters the steady-state composition of Au-catalyzed or self-catalyzed ternary III-V nanowires can be tuned to a desired value and why it is generally different from the vapor composition. Second, we present some experimental data and modeling results for the interfacial abruptness across axial nanowire heterostructures, both in Au-catalyzed and self-catalyzed VLS growth methods. Refined modeling allows us to formulate some general growth recipes for suppressing the unwanted reservoir effect in the droplet and sharpening the nanowire heterojunctions. We consider and refine two approaches developed to date, namely the regular crystallization model for a liquid alloy with a critical size of only one III-V pair at high supersaturations or classical binary nucleation theory with a macroscopic critical nucleus at modest supersaturations.

InGaAsP Mach-Zehnder interferometer optical modulator monolithically integrated with InGaAs driver MOSFET on a III-V CMOS photonics platform.

Science.gov (United States)

Park, Jin-Kown; Takagi, Shinichi; Takenaka, Mitsuru

2018-02-19

We demonstrated the monolithic integration of a carrier-injection InGaAsP Mach-Zehnder interferometer (MZI) optical modulator and InGaAs metal-oxide-semiconductor field-effect transistor (MOSFET) on a III-V-on-insulator (III-V-OI) wafer. A low-resistivity lateral PIN junction was formed along an InGaAsP rib waveguide by Zn diffusion and Ni-InGaAsP alloy, enabling direct driving of the InGaAsP optical modulator by the InGaAs MOSFET. A π phase shift of the InGaAsP optical modulator was obtained through the injection of a drain current from the InGaAs MOSFET with a gate voltage of approximately 1 V. This proof-of-concept demonstration of the monolithic integration of the InGaAsP optical modulator and InGaAs driver MOSFET will enable us to develop high-performance and low-power electronic-photonic integrated circuits on a III-V CMOS photonics platform.

Simultaneous Oxidation and Sequestration of As(III) from Water by Using Redox Polymer-Based Fe(III) Oxide Nanocomposite.

Science.gov (United States)

Zhang, Xiaolin; Wu, Mengfei; Dong, Hao; Li, Hongchao; Pan, Bingcai

2017-06-06

Water decontamination from As(III) is an urgent but still challenging task. Herein, we fabricated a bifunctional nanocomposite HFO@PS-Cl for highly efficient removal of As(III), with active chlorine covalently binding spherical polystyrene host for in situ oxidation of As(III) to As(V), and Fe(III) hydroxide (HFO) nanoparticles (NPs) embedded inside for specific As(V) removal. HFO@PS-Cl could work effectively in a wide pH range (5-9), and other substances like sulfate, chloride, bicarbonate, silicate, and humic acid exert insignificant effect on As(III) removal. As(III) sequestration is realized via two pathways, that is, oxidation to As(V) by the active chlorine followed by specific As(V) adsorption onto HFO NPs, and As(III) adsorption onto HFO NPs followed by oxidation to As(V). The exhausted HFO@PS-Cl could be refreshed for cyclic runs with insignificant capacity loss by the combined regeneration strategy, that is, alkaline solution to rinse the adsorbed As(V) and NaClO solution to renew the host oxidation capability. In addition, fixed-bed experiments demonstrated that the HFO@PS-Cl column could generate >1760 bed volume (BV) effluent from a synthetic As(III)-containing groundwater to meet the drinking water standard (nanocomposites, HFO@PS-N and HFO@D201 could only generate 450 and 600 BV effluents under otherwise identical conditions.

Progress in the development of metamorphic multi-junction III-V space solar cells

Energy Technology Data Exchange (ETDEWEB)

Sinharoy, S.; Patton, M.O.; Valko, T.M.; Weizer, V.G. [Essential Research Inc., Cleveland, OH (United States)

2002-07-01

Theoretical calculations have shown that highest-efficiency III-V multi-junction solar cells require alloy structures that cannot be grown on a lattice-matched substrate. Ever since the first demonstration of high efficiency metamorphic single-junction 1.1 and 1.2 eV InGaAs solar cells, interest has grown in the development of multi-junction cells of this type, using graded buffer layer technology. Essential Research Incorporated (ERI) is currently developing a dual-junction 1.6 eV InGaP/1.1 eV InGaAs tandem cell (projected practical air-mass zero (AMO), one-sun efficiency of 27%, and 100-sun efficiency of 31.1%) under a Ballistic Missile Defense Command (BMDO) SBIR Phase II program. A second ongoing research effort involves the development of a 2.1 eV A1GaInP/1.6 eV InGaAsP/1.2 eV InGaAs triple-junction concentrator tandem cell (projected practical AMO efficiency 36.5% under 100 suns) under a SBIR Phase II program funded by the Air Force. We are in the process of optimizing the dual-junction cell performance. For the triple-junction cell, we have developed the bottom and the middle cell, and are in the process of developing the layer structures needed for the top cell. A progress report is presented in this paper. (author)

Yields of base damage products in crystalline DNA produced by the direct-type effect

International Nuclear Information System (INIS)

Gilbert, D.C.; Bernhard, W.A.; Swarts, S.G.

2003-01-01

Our aim is to determine the yields of base damage products due to direct-type effects in well-defined DNA samples. The sample, crystalline d(GCACGCGTGC) 2 , which contains Co(III), has been structurally characterized by others using X-ray crystallography and the free radical yields measured by our laboratory using EPR spectroscopy. Polycrystalline samples were x-irradiated (70 KeV) at room temperature (RT) to doses up to 150 kGy. Following dissolution under air, the base products were identified and quantified using GC-MS. 7,8-dihydro-8-oxoguanine (8-oxo-G) is the primary base damage product found, with a yield of ∼0.09 μmoles/J, whereas 2,6-diamino-4-oxo-5-formamidopyrimidine (FpyG) was below the limits of detection of the GC-MS assay. Radiation yields for 5,6-dihydrothymine (DHT) and 5-hydroxymethyluracil of 0.0017 and 0.0042 μmoles/J, respectively, were also observed. These results differ from those obtained in a previous study of solid-state hydrated DNA irradiated at RT (Swarts et al., Radiat. Res. 145: 304-14, 1996), where the yields of FpyG and DHT were approximately 11% and 20% that of 8-oxo-G, respectively. Our working hypothesis is that Co(III) in crystalline d(GCACGCGTGC) 2 modifies the product distribution. Based on the EPR data, the influence of Co(III) on the initial distribution of radical trapping is negligible. This suggests that electron transfer from the pyrimidines to Co(III) occurs either upon annealing and/or upon solvation, thereby competing with dihydropyrimidine formation. While strand break (sb) yields for d(GCACGCGTGC) 2 are not yet completed, in earlier work on crystals of other oligomers, we obtained sb yields of 0.06-0.16 μmoles/J. We anticipate, therefore, that the stoichiometry between 8-oxo-G and sb formation will be about 1:1

Gel–sol synthesis and aging effect on highly crystalline anatase ...

Indian Academy of Sciences (India)

Gel–sol synthesis and aging effect on highly crystalline anatase nanopowder .... −1 in static air. To identify the gel-phase, it was mixed with D2O to form sample solution ... Ti(OH)4 chemical composition is produced this way: Ti3. [. (OC2H4)3 N. ].

Study on competitive adsorption mechanism among oxyacid-type heavy metals in co-existing system: Removal of aqueous As(V), Cr(III) and As(III) using magnetic iron oxide nanoparticles (MIONPs) as adsorbents

Science.gov (United States)

Lin, Sen; Lian, Cheng; Xu, Meng; Zhang, Wei; Liu, Lili; Lin, Kuangfei

2017-11-01

The adsorption and co-adsorption of As(V), Cr(VI) and As(III) onto the magnetic iron oxide nanoparticles (MIONPs) surface were investigated comprehensively to clarify the competitive processes. The results reflected that the MIONPs had remarkable preferential adsorption to As(V) compared with Cr(VI) and As(III). And it was determined, relying on the analysis of heavy metals variations on the MIONPs surface at different co-adsorption stages using FTIR and XPS, that the inner-sphere complexation made vital contribution to the preferential adsorption for As(V), corresponding with the replacement experiments where As(V) could grab extensively active sites on the MIONPs pre-occupied by As(III) or Cr(V) uniaxially. The desorption processes displayed that the strongest affinity between the MIONPs and As(V) where As(III) and Cr(VI) were more inclined to wash out. It is wish to provide a helpful direction with this study for the wastewater treatment involving multiple oxyacid-type heavy metals using MIONPs as adsorbents.

Structural features and electronic properties of group-III-, group-IV-, and group-V-doped Si nanocrystallites

International Nuclear Information System (INIS)

Ramos, L E; Degoli, Elena; Cantele, G; Ossicini, Stefano; Ninno, D; Furthmueller, J; Bechstedt, F

2007-01-01

We investigate the incorporation of group-III (B and Al), group-IV (C and Ge), and group-V (N and P) impurities in Si nanocrystallites. The structural features and electronic properties of doped Si nanocrystallites, which are faceted or spherical-like, are studied by means of an ab initio pseudopotential method including spin polarization. Jahn-Teller distortions occur in the neighborhood of the impurity sites and the bond lengths show a dependence on size and shape of the nanocrystallites. We find that the acceptor (group-III) and donor (group-V) levels become deep as the nanocrystallites become small. The energy difference between the spin-up and spin-down levels of group-III and group-V impurities decreases as the size of the Si nanocrystallite increases and tends to the value calculated for Si bulk. Doping with carbon introduces an impurity-related level in the energy gap of the Si nanocrystallites

Biotransformation of As (III to As (V and their stabilization in soil with Bacillus sp. XS2 isolated from gold mine tailing of Xinjiang, China

Directory of Open Access Journals (Sweden)

Santosh Kumar Karn

2016-09-01

Full Text Available Xinjiang province is one of the most polluted region in China, this region affected by multi-metal problem, especially arsenic (As affect very badly. Two major forms of As present in the environment As (III and As (V as compared to As (V, As (III is much more toxic. Our aim is to remediate As (III contaminated soil by using As (III resistant microbe, having the high transforming ability for As (III to As (V. An As (III oxidizing bacterium Bacillus sp. XS2, isolated and selected from gold mine tailing which have shown high resistance up to 6400 mg L−1 and efficiently transformed up to 4000 mg L−1 in sucrose low phosphate medium (SLP, higher than any of the previous reported Bacillus sp.. In soil, we found that XS2 successfully transformed up to 81% of soluble exchangeable fraction within 10 d in contaminated soil (with 500 mg kg−1, which makes it potential microbe for the removal of contaminated site with arsenic in the environment. Further XS2 was characterized for their molecular basis of resistance and we establish that XS2 having arsenic oxidase enzyme activity which is accountable for the detoxification of arsenic at high concentration and provide resistance to the bacterium. Gene encoding arsenic oxidase (aioA-gene was also amplified from this bacterium using polymerase chain reaction (PCR with degenerate primer. The aioA-gene is specific for the arsenite-oxidizing bacteria. The deduced amino acid sequence had shown 42% similarity with pseudomonas sp. arsenic oxidase. Further, the strain was characterized by 16s rRNA gene sequence analysis and shown maximum similarity with Bacillus sp.

Oxygen perovskites with pentavalent ruthenium A/sub 2/sup(II)Bsup(III)Rusup(V)O/sub 6/ with Asup(II) = Ba, Sr

Energy Technology Data Exchange (ETDEWEB)

Bader, H; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-07-01

The perovskites Ba/sub 2/Bsup(III)Rusup(V)O/sub 6/ with Bsup(III) = La, Nd, Sm, Eu, Gd, Dy, Y are cubic (Bsup(III) = La: a = 8.54 A; Y: a = 8.33 A) with a partial order for Bsup(III) and Rusup(V). The Sc compound, Ba/sub 2/ScRuO/sub 6/, has a hexagonal 6L structure (a = 5.79 A; c = 14.22 A; sequence (hcc)/sub 2/). The lattice of the Sr perovskites, Sr/sub 2/Bsup(III)Rusup(V)O/sub 6/, with Bsup(III) = Eu, Gd, Dy, Y is rhombic distorted. The IR and FIR spectra are discussed.

Dense Plasma Focus-Based Nanofabrication of III-V Semiconductors: Unique Features and Recent Advances.

Science.gov (United States)

Mangla, Onkar; Roy, Savita; Ostrikov, Kostya Ken

2015-12-29

The hot and dense plasma formed in modified dense plasma focus (DPF) device has been used worldwide for the nanofabrication of several materials. In this paper, we summarize the fabrication of III-V semiconductor nanostructures using the high fluence material ions produced by hot, dense and extremely non-equilibrium plasma generated in a modified DPF device. In addition, we present the recent results on the fabrication of porous nano-gallium arsenide (GaAs). The details of morphological, structural and optical properties of the fabricated nano-GaAs are provided. The effect of rapid thermal annealing on the above properties of porous nano-GaAs is studied. The study reveals that it is possible to tailor the size of pores with annealing temperature. The optical properties of these porous nano-GaAs also confirm the possibility to tailor the pore sizes upon annealing. Possible applications of the fabricated and subsequently annealed porous nano-GaAs in transmission-type photo-cathodes and visible optoelectronic devices are discussed. These results suggest that the modified DPF is an effective tool for nanofabrication of continuous and porous III-V semiconductor nanomaterials. Further opportunities for using the modified DPF device for the fabrication of novel nanostructures are discussed as well.

Synthesis of single-crystalline Al layers in sapphire

International Nuclear Information System (INIS)

Schlosser, W.; Lindner, J.K.N.; Zeitler, M.; Stritzker, B.

1999-01-01

Single-crystalline, buried aluminium layers were synthesized by 180 keV high-dose Al + ion implantation into sapphire at 500 deg. C. The approximately 70 nm thick Al layers exhibit in XTEM investigations locally abrupt interfaces to the single-crystalline Al 2 O 3 top layer and bulk, while thickness and depth position are subjected to variations. The layers grow by a ripening process of oriented Al precipitates, which at low doses exist at two different orientations. With increasing dose, precipitates with one out of the two orientations are observed to exist preferentially, finally leading to the formation of a single-crystalline layer. Al outdiffusion to the surface and the formation of spherical Al clusters at the surface are found to be competing processes to buried layer formation. The formation of Al layers is described by Rutherford Backscattering Spectroscopy (RBS), Cross-section transmission electron microscopy (XTEM) and Scanning electron microscopy (SEM) studies as a function of dose, temperature and substrate orientation

Nitrogen in highly crystalline carbon nanotubes

International Nuclear Information System (INIS)

Ducati, C; Koziol, K; Stavrinadis, A; Friedrichs, S; Windle, A H; Midgley, P A

2006-01-01

Multiwall carbon nanotubes (MWCNTs) with an unprecedented degree of internal order were synthesised by chemical vapour deposition (CVD) adding a nitrogen-containing compound to the hydrocarbon feedstock. Ferrocene was used as the metal catalyst precursor. The remarkable crystallinity of these nanotubes lies both in the isochirality and in the crystallographic register of their walls, as demonstrated by electron diffraction and high resolution electron microscopy experiments. High resolution transmission electron microscopy analysis shows that the walls of the nanotubes consist of truncated stacked cones, instead of perfect cylinders, with a range of apex angles that appears to be related to the nitrogen concentration in the synthesis process. The structure of armchair, zigzag and chiral nanotubes is modelled and discussed in terms of density of topological defects, providing an interesting comparison with our microscopy experiments. A growth mechanism based on the interplay of base- and tip-growth is proposed to account for our experimental observations

Comparison of SRP high-level waste disposal costs for borosilicate glass and crystalline ceramic waste forms

International Nuclear Information System (INIS)

McDonell, W.R.

1982-04-01

An evaluation of costs for the immobilization and repository disposal of SRP high-level wastes indicates that the borosilicate glass waste form is less costly than the crystalline ceramic waste form. The wastes were assumed immobilized as glass with 28% waste loading in 10,300 reference 24-in.-diameter canisters or as crystalline ceramic with 65% waste loading in either 3400 24-in.-diameter canisters or 5900 18-in.-diameter canisters. After an interim period of onsite storage, the canisters would be transported to the federal repository for burial. Total costs in undiscounted 1981 dollars of the waste disposal operations, excluding salt processing for which costs are not yet well defined, were about $2500 million for the borosilicate glass form in reference 24-in.-diameter canisters, compared to about $2900 million for the crystalline ceramic form in 24-in.-diameter canisters and about $3100 million for the crystalline ceramic form in 18-in.-diameter canisters. No large differences in salt processing costs for the borosilicate glass and crystalline ceramic forms are expected. Discounting to present values, because of a projected 2-year delay in startup of the DWPF for the crystalline ceramic form, preserved the overall cost advantage of the borosilicate glass form. The waste immobilization operations for the glass form were much less costly than for the crystalline ceramic form. The waste disposal operations, in contrast, were less costly for the crystalline ceramic form, due to fewer canisters requiring disposal; however, this advantage was not sufficient to offset the higher development and processing costs of the crystalline ceramic form. Changes in proposed Nuclear Regulatory Commission regulations to permit lower cost repository packages for defense high-level wastes would decrease the waste disposal costs of the more numerous borosilicate glass forms relative to the crystalline ceramic forms

Ion-assisted deposition of thin films

International Nuclear Information System (INIS)

Barnett, S.A.; Choi, C.H.; Kaspi, R.; Millunchick, J.M.

1993-01-01

Recent work on low-energy ion-assisted deposition of epitaxial films is reviewed. Much of the recent interest in this area has been centered on the use of very low ion energies (∼ 25 eV) and high fluxes (> 1 ion per deposited atom) obtained using novel ion-assisted deposition techniques. These methods have been applied in ultra-high vacuum, allowing the preparation of high-purity device-quality semiconductor materials. The following ion-surface interaction effects during epitaxy are discussed: improvements in crystalline perfection during low temperature epitaxy, ion damage, improved homogeneity and properties in III-V alloys grown within miscibility gaps, and changes in nucleation mechanism during heteroepitaxial growth

Adsorption of As(III), As(V) and Cu(II) on zirconium oxide immobilized alginate beads in aqueous phase.

Science.gov (United States)

Kwon, Oh-Hun; Kim, Jong-Oh; Cho, Dong-Wan; Kumar, Rahul; Baek, Seung Han; Kurade, Mayur B; Jeon, Byong-Hun

2016-10-01

A composite adsorbent to remove arsenite [As(III)], arsenate [As(V)], and copper [Cu(II)] from aqueous phase was synthesized by immobilizing zirconium oxide on alginate beads (ZOAB). The composition (wt%) of ZOAB (Zr-34.0; O-32.7; C-21.3; Ca-1.0) was confirmed by energy dispersive X-ray (EDX) analysis. Sorption studies were conducted on single and binary sorbate systems, and the effects of contact time, initial adsorbate concentration, and pH on the adsorption performance of ZOAB (pHPZC = 4.3) were monitored. The sorption process for As(III)/As(V) and Cu(II) reached an equilibrium state within 240 h and 24 h, respectively, with maximum sorption capacities of 32.3, 28.5, and 69.9 mg g(-1), respectively. The addition of Cu(II) was favorable for As(V) sorption in contrast to As(III). In the presence of 48.6 mg L(-1) Cu(II), the sorption capacity of As(V) increased from 1.5 to 3.8 mg g(-1) after 240 h. The sorption data for As(III)/As(V) and Cu(II) conformed the Freundlich and Langmuir isotherm models, respectively. The adsorption of As(III), As(V), and Cu(II) followed pseudo second order kinetics. The effect of arsenic species on Cu(II) sorption was insignificant. The results of present study demonstrated that the synthesized sorbent could be useful for the simultaneous removal of both anionic and cationic contaminants from wastewaters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Changes in histoanatomical distribution of types I, III and V collagen promote adaptative remodeling in posterior tibial tendon rupture

Directory of Open Access Journals (Sweden)

Érika Satomi

2008-01-01

Full Text Available INTRODUCTION: Posterior tibial tendon dysfunction is a common cause of adult flat foot deformity, and its etiology is unknown. PURPOSE: In this study, we characterized the morphologic pattern and distribution of types I, III and V collagen in posterior tibial tendon dysfunction. METHOD: Tendon samples from patients with and without posterior tibial tendon dysfunction were stained by immunofluorescence using antibodies against types I, III and V collagen. RESULTS: Control samples showed that type V deposited near the vessels only, while surgically obtained specimens displayed type V collagen surrounding other types of collagen fibers in thicker adventitial layers. Type III collagen levels were also increased in pathological specimens. On the other hand, amounts of collagen type I, which represents 95% of the total collagen amount in normal tendon, were decreased in pathological specimens. CONCLUSION: Fibrillogenesis in posterior tibial tendon dysfunction is altered due to higher expression of types III and V collagen and a decreased amount of collagen type I, which renders the originating fibrils structurally less resistant to mechanical forces.

High quality ZnO layers with adjustable refractive indices for integrated optics applications

NARCIS (Netherlands)

Heideman, Rene; Lambeck, Paul; Gardeniers, Johannes G.E.

1995-01-01

Thin (approx. 1 μm) crystalline ZnO films with a good optical quality and a good (0002) texture are grown under two considerably different process parameter sets using a r.f. planar magnetron sputtering unit. The optical parameters of the two corresponding ZnO layers are distinctly different: high

Synergic effect of tungstophosphoric acid and sonication for rapid synthesis of crystalline nanocellulose.

Science.gov (United States)

Hamid, Sharifah Bee Abd; Zain, Siti Khadijah; Das, Rasel; Centi, Gabriele

2016-03-15

The utilization of sonication in combination with tungstophosphoric acid (PWA) catalyst reduces dramatically the time of operations from 30h to 10min by using an optimum sonication power of 225W. The basic cellulosic structure is maintained, allowing preparing high-quality nanocellulose. The size of the nanocellulose obtained was in the range from 15 to 35nm in diameter and several hundred nanometers in length, with a high crystallinity of about 88%. The nanocellulose shows a surface charge of -38.2mV which allows to obtaina stable colloidal suspension. The surface tension of the stable, swollen aqueous nanocellulose was close to that of water. These characteristics, together with the fast procedure allowed from the synergic combination of PWA and sonication, evidence the high potential of the proposed method for the industrial production of nanocellulose having the properties required in many applications. Copyright © 2015. Published by Elsevier Ltd.

eggNOG v4.0

DEFF Research Database (Denmark)

Powell, Sean; Forslund, Kristoffer; Szklarczyk, Damian Milosz

2013-01-01

levels compared with 41 in eggNOGv3, (iii) identification and annotation of particularly closely related orthologous groups, facilitating analysis of related gene families, (iv) improvements of the clustering and functional annotation approach, (v) adoption of a revised tree building procedure based...... prioritizing the inclusion of high-quality genomes to minimize error propagation from incomplete proteome sets. Major technological advances include (i) a robust and scalable procedure for the identification and inclusion of high-quality genomes, (ii) provision of orthologous groups for 107 different taxonomic...... on the multiple alignments generated during the process and (vi) implementation of quality control procedures throughout the entire pipeline. As in previous versions, eggNOGv4 provides multiple sequence alignments and maximum-likelihood trees, as well as broad functional annotation. Users can access the complete...

30 CFR 57.22204 - Main fan operation and inspection (I-A, II-A, III, and V-A mines).

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Main fan operation and inspection (I-A, II-A, III, and V-A mines). 57.22204 Section 57.22204 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... Main fan operation and inspection (I-A, II-A, III, and V-A mines). Main fans shall be— (a) Provided...

Reduction of As(V) to As(III) by commercial ZVI or As(0) with acid-treated ZVI

International Nuclear Information System (INIS)

Sun, Fenglong; Osseo-Asare, Kwadwo A.; Chen, Yongsheng; Dempsey, Brian A.

2011-01-01

Graphical abstract: Acid-treated ZVI (right) reduced As(V) to the less toxic As(0) while commercial ZVI reduced As(V) to As(III). There was no lag phase in either reaction when rigorously anoxic conditions were maintained. Highlights: ► Acid-treated ZVI reduced As(V) to the less toxic As(0). ► Commercial ZVI reduced As(V) to As(III), which was not released to solution. ► Magnetite/Fe(II) did not reduce As(V) even though the reaction is thermodynamically spontaneous. ► No lag phase was observed in any of the reactions, contrary to prior reports. ► Rigorously anoxic conditions seem necessary for observing these reactions. - Abstract: Zero-valent iron (ZVI) consists of an elemental iron core surrounded by a shell of corrosion products, especially magnetite. ZVI is used for in situ removal or immobilization of a variety of contaminants but the mechanisms for removal of arsenic remain controversial and the mobility of arsenic after reaction with ZVI is uncertain. These issues were addressed by separately studying reactions of As(V) with magnetite, commercial ZVI, and acid-treated ZVI. Strictly anoxic conditions were used. Adsorption of As(V) on magnetite was fast with pH dependence similar to previous reports using oxic conditions. As(V) was not reduced by magnetite and Fe(II) although the reaction is thermodynamically spontaneous. As(V) reactions with ZVI were also fast and no lag phase was observed which was contrary to previous reports. Commercial ZVI reduced As(V) to As(III) only when As(V) was adsorbed, i.e., for pH < 7. As(III) was not released to solution. Acid-treated ZVI reduced As(V) to As(0), shown using wet chemical analyses and XANES/EXAFS. Comparisons were drawn between reactivity of acid-treated ZVI and nano-ZVI; if true then acid-treated ZVI could provide similar reactive benefits at lower cost.

Low-energy electron transmission and secondary-electron emission experiments on crystalline and molten long-chain alkanes

International Nuclear Information System (INIS)

Ueno, N.; Sugita, K.; Seki, K.; Inokuchi, H.

1986-01-01

This paper describes the results of low-energy electron transmission and secondary-electron emission experiments on thin films of long-chain alkanes deposited on metal substrates. The spectral changes due to crystal-melt phase transition were measured in situ in both experiments. The ground-state energy V 0 of the quasifree electron in crystalline state was determined to be 0.5 +- 0.1 eV. The value of V 0 for the molten state was found to be negative. Further, in the crystalline state evidence is found for a direct correspondence between the transmission maxima and the high value of the density of states in the conduction bands

III-V group compound semiconductor light-emitting element having a doped tantalum barrier layer

International Nuclear Information System (INIS)

Oanna, Y.; Ozawa, N.; Yamashita, M.; Yasuda, N.

1984-01-01

Disclosed is a III-V Group compound semiconductor light-emitting element having a III-V Group compound semiconductor body with a p-n junction and including a p-type layer involved in forming the p-n junction; and a multi-layer electrode mounted on the p-type layer of the semiconductor body. The electrode comprises a first layer of gold alloy containing a small amount of beryllium or zinc and formed in direct contact with the p-type layer of the semiconductor body and an uppermost layer formed of gold or aluminum. A tantalum layer doped with carbon, nitrogen and/or oxygen is formed between the first layer and the uppermost layer by means of vacuum vapor deposition

DX centers in III-V semiconductors under hydrostatic pressure

International Nuclear Information System (INIS)

Wolk, J.A.

1992-11-01

DX centers are deep level defects found in some III-V semiconductors. They have persistent photoconductivity and large difference between thermal and optical ionization energies. Hydrostatic pressure was used to study microstructure of these defects. A new local vibrational mode (LVM) was observed in hydrostatically stressed, Si-doped GaAs. Corresponding infrared absorption peak is distinct from the Si Ga shallow donor LVM peak, which is the only other LVM peak observed in our samples, and is assigned to the Si DX center. Analysis of the relative intensities of the Si DX LVM and the Si shallow donor LVM peaks, combined with Hall effect and resistivity indicate that the Si DX center is negatively charged. Frequency of this new mode provides clues to the structure of this defect. A pressure induced deep donor level in S-doped InP was also discovered which has the properties of a DX center. Pressure at which the new defect becomes more stable than the shallow donor is 82 kbar. Optical ionization energy and energy dependence of the optical absorption cross section was measured for this new effect. Capture barrier from the conduction band into the DX state were also determined. That DX centers can be formed in InP by pressure suggests that DX states should be common in n-type III-V semiconductors. A method is suggested for predicting under what conditions these defects will be the most stable form of the donor impurity

Appearance of large crystalline domains in VO{sub 2} films grown on sapphire (001) and their phase transition characteristics

Energy Technology Data Exchange (ETDEWEB)

Azhan, Nurul Hanis; Su, Kui; Okimura, Kunio, E-mail: okifn@keyaki.cc.u-tokai.ac.jp [Graduate School of Science and Technology, Tokai University, Hiratsuka 259-1292 (Japan); Zaghrioui, Mustapha; Sakai, Joe [GREMAN, UMR 7347 CNRS, Université François Rabelais de Tours, Parc de Grandmont 37200 Tours (France)

2015-06-28

We report the first observation of large crystalline domains of several μm-size in VO{sub 2} films deposited on Al{sub 2}O{sub 3} (001) substrates by rf-biased reactive sputtering technique. The large crystalline domains, dominated with random in-plane oriented growth of (011){sub M1}-orientation, appear only under adequate substrate biasing, such as 10 W, while most biasing conditions result in conventional nanosized grains of highly oriented (010){sub M1}-orientation. Two temperature-controlled analyses, x-ray diffraction and micro-Raman spectroscopy, have revealed that some parts of large crystalline domains undergo intermediate monoclinic (M2) phase during the thermally-induced structural phase transition from monoclinic (M1) to rutile-tetragonal (R) phase. As an effect of the appearance of large crystalline domains, the film showed in-plane tensile stress, resulting in high T{sub IMT} of 69 °C due to the elongation of the V-V distance in its low-temperature monoclinic phase.

High quality antireflective ZnS thin films prepared by chemical bath deposition

International Nuclear Information System (INIS)

Tec-Yam, S.; Rojas, J.; Rejón, V.; Oliva, A.I.

2012-01-01

Zinc sulfide (ZnS) thin films for antireflective applications were deposited on glass substrates by chemical bath deposition (CBD). Chemical analysis of the soluble species permits to predict the optimal pH conditions to obtain high quality ZnS films. For the CBD, the ZnCl 2 , NH 4 NO 3 , and CS(NH 2 ) 2 were fixed components, whereas the KOH concentration was varied from 0.8 to 1.4 M. Groups of samples with deposition times from 60 to 120 min were prepared in a bath with magnetic agitation and heated at 90 °C. ZnS films obtained from optimal KOH concentrations of 0.9 M and 1.0 M exhibited high transparency, homogeneity, adherence, and crystalline. The ZnS films presented a band gap energy of 3.84 eV, an atomic Zn:S stoichiometry ratio of 49:51, a transmittance above 85% in the 300–800 nm wavelength range, and a reflectance below 25% in the UV–Vis range. X-ray diffraction analysis revealed a cubic structure in the (111) orientation for the films. The thickness of the films was tuned between 60 nm and 135 nm by controlling the deposition time and KOH concentration. The incorporation of the CBD-ZnS films into ITO/ZnS/CdS/CdTe and glass/Mo/ZnS heterostructures as antireflective layer confirms their high optical quality. -- Highlights: ► High quality ZnS thin films were prepared by chemical bath deposition (CBD). ► Better CBD-ZnS films were achieved by using 0.9 M-KOH concentration. ► Reduction in the reflectance was obtained for ZnS films used as buffer layers.

Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

KAUST Repository

Diao, Ying

2013-06-02

Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach - termed fluid-enhanced crystal engineering (FLUENCE) - that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s -1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics. © 2013 Macmillan Publishers Limited. All rights reserved.

Solubility of crystalline organic compounds in high and low molecular weight amorphous matrices above and below the glass transition by zero enthalpy extrapolation.

Science.gov (United States)

Amharar, Youness; Curtin, Vincent; Gallagher, Kieran H; Healy, Anne Marie

2014-09-10

Pharmaceutical applications which require knowledge of the solubility of a crystalline compound in an amorphous matrix are abundant in the literature. Several methods that allow the determination of such data have been reported, but so far have only been applicable to amorphous polymers above the glass transition of the resulting composites. The current work presents, for the first time, a reliable method for the determination of the solubility of crystalline pharmaceutical compounds in high and low molecular weight amorphous matrices at the glass transition and at room temperature (i.e. below the glass transition temperature), respectively. The solubilities of mannitol and indomethacin in polyvinyl pyrrolidone (PVP) K15 and PVP K25, respectively were measured at different temperatures. Mixtures of undissolved crystalline solute and saturated amorphous phase were obtained by annealing at a given temperature. The solubility at this temperature was then obtained by measuring the melting enthalpy of the crystalline phase, plotting it as a function of composition and extrapolating to zero enthalpy. This new method yielded results in accordance with the predictions reported in the literature. The method was also adapted for the measurement of the solubility of crystalline low molecular weight excipients in amorphous active pharmaceutical ingredients (APIs). The solubility of mannitol, glutaric acid and adipic acid in both indomethacin and sulfadimidine was experimentally determined and successfully compared with the difference between their respective calculated Hildebrand solubility parameters. As expected from the calculations, the dicarboxylic acids exhibited a high solubility in both amorphous indomethacin and sulfadimidine, whereas mannitol was almost insoluble in the same amorphous phases at room temperature. This work constitutes the first report of the methodology for determining an experimentally measured solubility for a low molecular weight crystalline solute

Menadione degrades the optical quality and mitochondrial integrity of bovine crystalline lenses.

Science.gov (United States)

Olsen, Kenneth W; Bantseev, Vladimir; Choh, Vivan

2011-01-26

The crystalline lens is a unique cellular organ that performs metabolic processes while maintaining transparency for optical functionality. Mitochondria play a role in providing cells with aerobic respiration necessary for these metabolic processes. Using menadione, a mitochondria-specific inhibitor of the quinone family, and bovine lenses in vitro, this study was undertaken to determine whether a relationship exists between mitochondrial function and optical function. Bovine lenses were treated with 50 μM, 200 μM, 600 μM, and 1,000 μM menadione and lens optical function, assessed as optical quality, was observed over 9 days. Confocal micrographs of mitochondria in superficial secondary fiber cells were also analyzed in 50 μM, 200 μM, and 600 μM menadione-treated lenses over 48 h. A decrease in lens optical quality was observed in a dose-dependent manner within 24 h for the 200 µM- (p=0.0422), 600 µM- (pmenadione. The data show that menadione has a detrimental effect on mitochondrial integrity and this change is associated with degradation of optical quality, suggesting a possible link between mitochondrial function and optical function.

Complexation of the actinides (III, IV and V) with organic acids

International Nuclear Information System (INIS)

Leguay, S.

2012-01-01

A thorough knowledge of the chemical properties of actinides is now required in a wide variety of fields: extraction processes involved in spent fuel reprocessing, groundwater in the vicinity of radioactive waste packages, environmental and biological media in the case of accidental release of radionuclides. In this context, the present work has been focused on the complexation of Am(III), Cm(III), Cf(III), Pu(IV) and Pa(V) with organic ligands: DTPA, NTA and citric acid. The complexation of pentavalent protactinium with citric and nitrilotriacetic acids was studied using liquid-liquid extraction with the element at tracer scale (C Pa ≤ 10 -10 M). The order and the mean charge of each complex were determined from the analysis of the systematic variations of the distribution coefficient of Pa(V) as function of ligand and proton concentration. Then, the apparent formation constants related of the so-identified complexes were calculated. The complexation of trivalent actinides with DTPA was studied by fluorescence spectroscopy (TRLFS) and capillary electrophoresis (CE-ICP-MS). The coexistence of the mono-protonated and non-protonated complexes (AnHDTPA - and AnDTPA 2- ) in acidic media (1.5 ≤ pH ≤ 3.5) was shown unambiguously. Literature data have been reinterpreted by taking into account both complexes and a consistent set of formation constants of An(III)-DTPA has been obtained. The experimental study was completed by theoretical calculations (DFT) on Cm-DTPA system. The coordination geometry of Cm in CmDTPA 2- and CmHDTPA - including water molecules in the first coordination sphere has been determined as well as interatomic distances. Finally, a study on the complexation of Pu(IV) with DTPA was initiated in order to more closely mimic physiological conditions. A three-step approach was proposed to avoid plutonium hydrolysis: i/ complexation of Pu(IV) with (NTA) in order to protect Pu(IV) from hydrolysis (at low pH) ii/ increase of pH toward neutral conditions

Attenuation of Thermal Neutrons by Crystalline Silicon

International Nuclear Information System (INIS)

Adib, M.; Habib, N.; Ashry, A.; Fathalla, M.

2002-01-01

A simple formula is given which allows to calculate the contribution of the total neutron cross - section including the Bragg scattering from different (hkt) planes to the neutron * transmission through a solid crystalline silicon. The formula takes into account the silicon form of poly or mono crystals and its parameters. A computer program DSIC was developed to provide the required calculations. The calculated values of the total neutron cross-section of perfect silicon crystal at room and liquid nitrogen temperatures were compared with the experimental ones. The obtained agreement shows that the simple formula fits the experimental data with sufficient accuracy .A good agreement was also obtained between the calculated and measured values of polycrystalline silicon in the energy range from 5 eV to 500μ eV. The feasibility study on using a poly-crystalline silicon as a cold neutron filter and mono-crystalline as a thermal neutron one is given. The optimum crystal thickness, mosaic spread, temperature and cutting plane for efficiently transmitting the thermal reactor neutrons, while rejecting both fast neutrons and gamma rays accompanying the thermal ones for the mono crystalline silicon are also given

Avalanche solar blind photodetectors based on single crystalline Mg0.47Zn0.53O thin film on Ga:ZnO substrate

Science.gov (United States)

Chen, Hao; Zhang, Jingtao; Chen, Zuxin; Liu, Huiqiang; Ma, Xinzhou; Li, Qiuguo; Chu, Guang; Chu, Sheng

2018-05-01

Single crystalline wurtzite Mg0.47Zn0.53O films were grown on Ga:ZnO substrates by pulse laser deposition. The band gap of the films was measured to be 4.43 eV. Vertical devices were fabricated for solar blind photodetection, realizing a high responsivity of 2 A W‑1 at 278 nm and  ‑5 V bias as well as a rejection ratio (R 278 nm/R 350 nm) of over 6  ×  103. A cut-off wavelength of 286 nm and a response time of 77 ms were also achieved. Besides, the devices showed stable response without degeneration under repeating illumination. The high performance of this photodetector was analyzed and attributed to the avalanche effect from high quality Mg0.47Zn0.53O/Ga:ZnO heterojunction at reverse bias. The avalanche gain was calculated to be 14.5 at  ‑10 V.

Speciation of As(III), As(V), MMA and DMA in contaminated soil extracts by HPLC-ICP/MS

Energy Technology Data Exchange (ETDEWEB)

Bissen, M.; Frimmel, F.H. [Engler-Bunte-Institut, Univ. Karlsruhe (Germany)

2000-05-01

A method to separate and quantify two inorganic arsenic species As(III) and As(V) and two organic arsenic species, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), by HPLC-ICP/MS has been developed. The separation of arsenic species was achieved on the anionic exchange column IonPac {sup trademark} AS11 (Dionex) with NaOH as mobile phase. The technique was successfully applied to analyze extracts of two contaminated soils, sampled at a former tannery site (soil 1) and a former paint production site (soil 2). The soils were extracted at pH values similar to the natural environment. Extractions were performed at different pH values with 0.3 M ammonium oxalate (pH = 3), milli-Q water (pH = 5.8), 0.3 M sodium carbonate (pH = 8) and 0.3 M sodium bicarbonate (pH = 11). No organically bound arsenic was found in the extracts. As(V) was the major component. Only up to 0.04% of the total arsenic contained in soil 1 were mobilized. The highest amount of extracted arsenic was found at the highest pH. In the milli-Q water extract of soil 1 As(III) and As(V) were found. High amounts of As(V) were found in the extracts of soil 2. Up to 20% of the total arsenic bound to soil 2 constituents were released. The results show that the mobilization of arsenic depended on the pH value of the extraction solution and the kind of extracted soil. Dramatic consequences have to be expected for pH changes in the environment especially in cases where soils contain high amounts of mobile arsenic. (orig.)

High-dose MeV electron irradiation of Si-SiO2 structures implanted with high doses Si+

Science.gov (United States)

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

2018-03-01

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

Region III involvement in quality control and quality assurance of radon testing methods

International Nuclear Information System (INIS)

Coyle, F.T.

1990-01-01

Region III has set a goal of increasing the testing for radon by our residents. One approach to this goal, is to bolster the public's confidence in the testing laboratories. We believe that this can be done most effectively by assuring the quality of the measurements available to the public. All Proficient Laboratories and Pennsylvania Certified Laboratories have submitted a quality assurance (QA) program. A QA audit checklist has been developed which will be finalized and made available to the states in our Region. This paper deals with inspection, verification, and documentation of the various laboratories and their compliance with prudent measuring protocols and addresses the following items: Organization and responsibilities; Sampling procedures; Detector chain of custody; Measurement procedures, quality control checks; State certification and RMP; Data resection, validation, and reporting; Quality assurance reports to management; Interview and discussion of QA audit with responsible officer

Narrow-linewidth Si/III-V lasers: A study of laser dynamics and nonlinear effects

Science.gov (United States)

Vilenchik, Yaakov Yasha

Narrow-linewidth lasers play an important role in a wide variety of applications, from sensing and spectroscopy to optical communication and on-chip clocks. Current narrow-linewidth systems are usually implemented in doped fibers and are big, expensive, and power-hungry. Semiconductor lasers compete favorably in size, cost, and power consumption, but their linewidth is historically limited to the sub-MHz regime. However, it has been recently demonstrated that a new design paradigm, in which the optical energy is stored away from the active region in a composite high-Q resonator, has the potential to dramatically improve the coherence of the laser. This work explores this design paradigm, as applied on the hybrid Si/III-V platform. It demonstrates a record sub-KHz white-noise-floor linewidth. It further shows, both theoretically and experimentally, that this strategy practically eliminates Henry's linewidth enhancement by positioning a damped relaxation resonance at frequencies as low as 70 MHz, yielding truly quantum limited devices at frequencies of interest. In addition to this empirical contribution, this work explores the limits of performance of this platform. Here, the effect of two-photon-absorption and free-carrier-absorption are analyzed, using modified rate equations and Langevin force approach. The analysis predicts that as the intra-cavity field intensity builds up in the high-Q resonator, non-linear effects cause a new domain of performance-limiting factors. Steady-state behavior, laser dynamics, and frequency noise performance are examined in the context of this unique platform, pointing at the importance of nonlinear effects. This work offers a theoretical model predicting laser performance in light of nonlinear effects, obtaining a good agreement with experimental results from fabricated high-Q Si/III-V lasers. In addition to demonstrating unprecedented semiconductor laser performance, this work establishes a first attempt to predict and demonstrate

Enzymatic transesterification of soybean oil with ethanol using lipases immobilized on highly crystalline PVA microspheres

International Nuclear Information System (INIS)

Bergamasco, Juliana; Araujo, Marcelo V. de; Vasconcellos, Adriano de; Luizon Filho, Roberto A.; Hatanaka, Rafael R.; Giotto, Marcus V.; Aranda, Donato A.G.; Nery, José G.

2013-01-01

Polyvinyl alcohol (PVA) microspheres with different degree of crystallinity were used as solid supports for Rhizomucor miehei lipase immobilization, and the enzyme-PVA complexes were used as biocatalysts for the transesterification of soybean oil to fatty acid ethyl esters (FAEE). The amounts of immobilized enzyme on the polymeric supports were similar for both the amorphous microspheres (PVA4) and the high crystalline microspheres (PVA25). However, the enzymatic activity of the immobilized enzymes was depended on the crystallinity degree of the PVA microspheres: enzymes immobilized on the PVA4 microspheres have shown low enzymatic activity (6.13 U mg −1 ), in comparison with enzymes immobilized on the high crystalline PVA25 microspheres (149.15 U mg −1 ). A synergistic effect was observed for the enzyme-PVA25 complex during the transesterification reaction of soybean oil to FAEE: transesterification reactions with free enzyme with the equivalent amount of enzyme that were immobilized onto the PVA25 microspheres (5.4 U) have yielded only 20% of FAEE, reactions with the pure highly crystalline microsphere PVA25 have not yielded FAEE, however reactions with the enzyme-PVA25 complexes have yielded 66.3% of FAEE. This synergistic effect of an immobilized enzyme on a polymeric support has not been observed before for transesterification reaction of triacylglycerides into FAEE. Based on ATR-FTIR, 23 Na- and 13 C-NMR-MAS spectroscopic data and the interaction of the polymeric network intermolecular hydrogen bonds with the lipases residual amino acids a possible explanation for this synergistic effect is provided. Highlights: • Rhizomucor miehei lipase was immobilized on PVA microspheres (PVA4, PVA12, PVA25). • Polymer-enzyme complex was characterized by XDR, SEM, ATR-FTIR, 13 C-CPMAS-NMR, 23 Na-MAS-NMR. • Polymer-enzymes (PVA12 and PVA25) enzymes yielded considerable amount of ethyl esters. • Synergistic effect was observed for the polymer-enzyme complexes

Immunohistochemical expression of mitochondrial membrane complexes (MMCs) I, III, IV and V in malignant and benign periampullary epithelium: a potential target for drug therapy of periampullary cancer?

International Nuclear Information System (INIS)

Aloysius, Mark M; Zaitoun, Abed M; Bates, Timothy E; Ilyas, Mohammad; Constantin-Teodosiu, Dumitru; Rowlands, Brian J; Lobo, Dileep N

2010-01-01

Mitochondrial membrane complexes (MMCs) are key mediators of cellular oxidative phosphorylation, and inhibiting them could lead to cell death. No published data are available on the relative abundance of MMCs in different periampullary cancers. Therefore, we studied the expression profile of MMCs I, III, IV and V in periampullary cancers, reactive pancreatitis, normal pancreas and chronic pancreatitis. This was a retrospective study on tissue microarrays constructed from formalin-fixed paraffin-embedded tissue from 126 consecutive patients (cancer = 104, chronic pancreatitis = 22) undergoing pancreatic resections between June 2001 and June 2006. 78 specimens of chronic pancreatitis tissue were obtained adjacent to areas of cancer. Normal pancreatic tissue was obtained from the resection specimens in a total of 30 patients. Metastatic tumours in 61 regional lymph nodes from 61 patients were also studied. MMCs I, III, IV and V were highly expressed (p < 0.05) in all primary periampullary cancers compared with metastatic lymph nodes and adjacent benign pancreas. MMCs III, IV and V were highly expressed in all cancers regardless of type compared with chronic pancreatitis (p < 0.05). Higher expression of MMCs I and V was associated with better survival and may, in part, relate to lower expression of these MMCs in poorly differentiated tumours compared with well and moderately differentiated tumours. Differential expression of MMCs III, IV and V in primary periampullary cancers compared with adjacent benign periampullary tissue and chronic pancreatitis is a novel finding, which may render them attractive anticancer targets

Structural and electrochemical properties of single crystalline MoV 2O8 nanowires for energy storage devices

KAUST Repository

Shahid, Muhammad; Liu, Jingling; Ali, Zahid; Shakir, Imran; Warsi, Muhammad Farooq

2013-01-01

We report the synthesis of MoV2O8 nanowires of high quality using spin coating followed by the thermal annealing process. Transmission electron microscopy (TEM) reveals the average diameter of synthesized nanowire about 100 nm, and average length ranges from 1 to 5 μm. The TEM analysis further confirms the <001> growth direction of MoV 2O8 nanowires. The electrochemical properties of synthesized nanowires using cyclic voltammetry show the specific capacitance 56 Fg-1 at the scan rate of 5 mV s-1 that remains 24 Fg -1 at 100 mV s-1. The electrochemical measurements suggest that the MoV2O8 nanowires can be used as a material for the future electrochemical capacitors (energy storage devices). © 2012 Published by Elsevier Inc. All rights reserved.

Structural and electrochemical properties of single crystalline MoV 2O8 nanowires for energy storage devices

KAUST Repository

Shahid, Muhammad

2013-05-01

We report the synthesis of MoV2O8 nanowires of high quality using spin coating followed by the thermal annealing process. Transmission electron microscopy (TEM) reveals the average diameter of synthesized nanowire about 100 nm, and average length ranges from 1 to 5 μm. The TEM analysis further confirms the <001> growth direction of MoV 2O8 nanowires. The electrochemical properties of synthesized nanowires using cyclic voltammetry show the specific capacitance 56 Fg-1 at the scan rate of 5 mV s-1 that remains 24 Fg -1 at 100 mV s-1. The electrochemical measurements suggest that the MoV2O8 nanowires can be used as a material for the future electrochemical capacitors (energy storage devices). © 2012 Published by Elsevier Inc. All rights reserved.

The High Energy Materials Science Beamline (HEMS) at PETRA III

International Nuclear Information System (INIS)

Schell, Norbert; King, Andrew; Beckmann, Felix; Ruhnau, Hans-Ulrich; Kirchhof, Rene; Kiehn, Ruediger; Mueller, Martin; Schreyer, Andreas

2010-01-01

The HEMS Beamline at the German high-brilliance synchrotron radiation storage ring PETRA III is fully tunable between 30 and 250 keV and optimized for sub-micrometer focusing. Approximately 70 % of the beamtime will be dedicated to Materials Research. Fundamental research will encompass metallurgy, physics and chemistry with first experiments planned for the investigation of the relationship between macroscopic and micro-structural properties of polycrystalline materials, grain-grain-interactions, and the development of smart materials or processes. For this purpose a 3D-microsctructure-mapper has been designed. Applied research for manufacturing process optimization will benefit from high flux in combination with ultra-fast detector systems allowing complex and highly dynamic in-situ studies of micro-structural transformations, e.g. during welding processes. The beamline infrastructure allows accommodation of large and heavy user provided equipment. Experiments targeting the industrial user community will be based on well established techniques with standardized evaluation, allowing full service measurements, e.g. for tomography and texture determination. The beamline consists of a five meter in-vacuum undulator, a general optics hutch, an in-house test facility and three independent experimental hutches working alternately, plus additional set-up and storage space for long-term experiments. HEMS is under commissioning as one of the first beamlines running at PETRA III.

Diagnostic accuracy of circulating thyrotropin receptor messenger RNA combined with neck ultrasonography in patients with Bethesda III-V thyroid cytology.

Science.gov (United States)

Aliyev, Altay; Patel, Jinesh; Brainard, Jennifer; Gupta, Manjula; Nasr, Christian; Hatipoglu, Betul; Siperstein, Allan; Berber, Eren

2016-01-01

The aim of this study was to analyze the usefulness of thyrotropin receptor messenger RNA (TSHR-mRNA) combined with neck ultrasonography (US) in the management of thyroid nodules with Bethesda III-V cytology. Cytology slides of patients with a preoperative fine needle aspiration (FNA) and TSHR-mRNA who underwent thyroidectomy between 2002 and 2011 were recategorized based on the Bethesda classification. Results of thyroid FNA, TSHR-mRNA, and US were compared with the final pathology. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. There were 12 patients with Bethesda III, 112 with Bethesda IV, and 58 with Bethesda V cytology. The sensitivity of TSHR-mRNA in predicting cancer was 33%, 65%, and 79 %, and specificity was 67%, 66%, and 71%, for Bethesda III, IV, and V categories, respectively. For the same categories, the PPV of TSHR-mRNA was 25%, 33%, and 79%, respectively; whereas the NPV was 75%, 88%, and 71%, respectively. The addition of neck US to TSHR-mRNA increased the NPV to 100% for Bethesda III, and 86%, for Bethesda IV, and 82% for Bethesda V disease. This study documents the potential usefulness of TSHR-mRNA for thyroid nodules with Bethesda III-V FNA categories. TSHR-mRNA may be used to exclude Bethesda IV disease. A large sample analysis is needed to determine its accuracy for Bethesda category III nodules. Copyright © 2016 Elsevier Inc. All rights reserved.

Microstructurally Based Prediction of High Strain Failure Modes in Crystalline Solids

Science.gov (United States)

2016-07-05

interfaces in hcp– fcc systems subjected to high strain-rate deformation and fracture modes, Journal of Materials Research, (8 2015): 0. doi: 10.1557/jmr...rupture • Comparison and validation with experimental observations/ measurements • New dislocation-density crystalline plasticity that accounts for...relationships between coherent interfaces in hcp– fcc systems subjected to high strain-rate deformation and fracture modes, Journal of Materials Research, Vol. 30

Creep in crystalline rock with application to high level nuclear waste repository

International Nuclear Information System (INIS)

Eloranta, P.; Simonen, A.

1992-06-01

The time-dependent strength and deformation properties of hard crystalline rock are studied. Theoretical models defining the phenomena which can effect these properties are reviewed. The time- dependent deformation of the openings in the proposed nuclear waste repository is analysed. The most important factors affecting the subcritical crack growth in crystalline rock are the stress state, the chemical environment, temperature and microstructure of the rock. There are several theoretical models for the analysis of creep and cyclic fatigue: deformation diagrams, rheological models thermodynamic models, reaction rate models, stochastic models, damage models and time-dependent safety factor model. They are defective in describing the three-axial stress condition and strength criteria. In addition, the required parameters are often too difficult to determine with adequate accuracy. Therefore these models are seldom applied in practice. The effect of microcrack- driven creep on the stability of the work shaft, the emplacement tunnel and the capsulation hole of a proposed nuclear waste repository was studied using a numerical model developed by Atomic Energy of Canada Ltd. According to the model, the microcrack driven creep progresses very slowly in good quality rock. Poor rock quality may accelerate the creep rate. The model is very sensitive to the properties of the rock and secondary stress state. The results show that creep causes no stability problems on excavations in good rock. The results overestimate the effect of the creep, because the analysis omitted the effect of support structures and backfilling

Solvent Extraction and Separation of Chromium(III) and (V I) in Aqueous Solutions with Trioctylphosphine Oxide

International Nuclear Information System (INIS)

Sekine, T.; Yamada, M.

1999-01-01

The solvent extraction of chromium(III) and (V I) in aqueous solutions with a solvating type extractant, trioctylphosphine oxide(TOPO), in hexane is studied. Kinetically inert Cr 3+ is extracted from 1 mol dm -3 sodium perchlorate solution very quickly and quantitatively as Cr(H 2 O · TOPO) 6 3+ (CIO 4 -) 3 . Chromium(V I) in hydrochloric acid is extracted effectively as the H 2 CrO $ (H CI) n centre dot TOPO m species ( m = 2 or 3, n = 0 to 2) and the distribution ratio increased by an increase in the acid concentration. From these, a procedure is proposed for the extraction of both chromium(V I) and chromium(III) in aqueous solution separately with 0.1 mol dm -3 TOPO in hexane

Effects of Mg/Ga and V/III source ratios on hole concentration of N-polar (000\\bar{1}) p-type GaN grown by metalorganic vapor phase epitaxy

Science.gov (United States)

Nonoda, Ryohei; Shojiki, Kanako; Tanikawa, Tomoyuki; Kuboya, Shigeyuki; Katayama, Ryuji; Matsuoka, Takashi

2016-05-01

The effects of growth conditions such as Mg/Ga and V/III ratios on the properties of N-polar (000\\bar{1}) p-type GaN grown by metalorganic vapor phase epitaxy were studied. Photoluminescence spectra from Mg-doped GaN depended on Mg/Ga and V/III ratios. For the lightly doped samples, the band-to-acceptor emission was observed at 3.3 eV and its relative intensity decreased with increasing V/III ratio. For the heavily doped samples, the donor-acceptor pair emission was observed at 2.8 eV and its peak intensity monotonically decreased with V/III ratio. The hole concentration was maximum for the Mg/Ga ratio. This is the same tendency as in group-III polar (0001) growth. The V/III ratio also reduced the hole concentration. The higher V/III ratio reduced the concentration of residual donors such as oxygen by substituting nitrogen atoms. The surface became rougher with increasing V/III ratio and the hillock density increased.

Technetium cyanide chemistry: synthesis and characterization of technetium(III) and -(V) cyanide complexes

International Nuclear Information System (INIS)

Trop, H.S.; Jones, A.G.; Davison, A.

1980-01-01

Several new technetium cyanide complexes have been prepared and characterized. The reaction of ammonium hexaiodotechnetate(IV) with potassium cyanide in refluxing aqueous methanol under nitrogen yields potassium heptacyanotechnetate(III) dihydrate, K 4 Tc(CN) 7 .2H 2 O (1). Infrared and Raman measurements indicate that 1 has a pentagonal bipyramidal structure (D/sub 5h/) in both solid and solution. Aqueous solutions of 1 are air sensitive, decomposing to potassium oxopentacyanotechnetate(V) tetrahydrate, K 2 TcO(CN) 5 .4H 2 O (2). This species can also be prepared from the reaction of TcO 2 .xH 2 O with hot aqueous potassium cyanide solutions. Hydrolysis of 2 in water yields potassium trans-dioxo-tetracyanotechnetate(V), K 3 TcO 2 (CN) 4 (3). Preparation of 3 can also be achieved from the treatment of [TcO 2 (Py) 4 ]ClO 4 .2H 2 O with aqueous potassium cyanide. Infrared and Raman measurements on 3 are consistent with the proposed trans-dioxo (D/sub 4h/) structure. Reaction of the oxotetrachlorotechnetate(V) anion, TcOCl 4 , with potassium cyanide in methanol produces trans-oxomethoxytetracyanotechnetate(V). [TcO(OMe)(CN) 4 ] (4). The full details of the synthesis and characterization of these interesting technetium(III) and -(V) complexes, as well as observations on the infrared and Raman spectra of trans-dioxo metal complexes and the hydrolysis of species 2, are presented

X-ray absorption spectroscopy as a tool investigating arsenic(III) and arsenic(V) sorption by an aluminum-based drinking-water treatment residual.

Science.gov (United States)

Makris, Konstantinos C; Sarkar, Dibyendu; Parsons, Jason G; Datta, Rupali; Gardea-Torresdey, Jorge L

2009-11-15

Historic applications of arsenical pesticides to agricultural land have resulted in accumulation of residual arsenic (As) in such soils. In situ immobilization represents a cost-effective and least ecological disrupting treatment technology for soil As. Earlier work in our laboratory showed that drinking-water treatment residuals (WTRs), a low-cost, waste by-product of the drinking-water treatment process exhibit a high affinity for As. Wet chemical experiments (sorption kinetics and desorption) were coupled with X-ray absorption spectroscopy measurements to elucidate the bonding strength and type of As(V) and As(III) sorption by an aluminum-based WTR. A fast (1h), followed by a slower sorption stage resulted in As(V) and As(III) sorption capacities of 96% and 77%, respectively. Arsenic desorption with a 5mM oxalate from the WTR was minimal, being always absorption spectroscopy data showed inner-sphere complexation between As and surface hydroxyls. Reaction time (up to 48h) had no effect on the initial As oxidation state for sorbed As(V) and As(III). A combination of inner-sphere bonding types occurred between As and Al on the WTR surface because mixed surface geometries and interatomic distances were observed.

Template synthesis of highly crystalline and monodisperse iron oxide pigments of nanosize

International Nuclear Information System (INIS)

Sreeram, Kalarical Janardhanan; Indumathy, Ramasamy; Rajaram, Ananthanarayanan; Nair, Balachandran Unni; Ramasami, Thirumalachari

2006-01-01

Synthesis of highly crystalline and monodisperse iron oxide nanoparticles is reported. The separation of Fe centers through site-specific binding to a polysaccharide-alginate matrix enables the generation of particles with a monodisperse or narrow size distribution character, resulting in transparent pigments. Site-specific interactions coupled with gel like character of alginate is proposed as the mechanism behind generation of lower particle sizes. Alginate-Fe complexes developed were subjected to heat treatment to provide for crystalline character and development of hematite (α-Fe 2 O 3 ). Conditions most ideal for achieving monodispersity and lower sizes have been optimized and confirmed through microscopic and photon correlation spectroscopic measurements

Highly selective electrodeposition of sub-10 nm crystalline noble metallic nanorods inside vertically aligned multiwall carbon nanotubes

Science.gov (United States)

Wang, Xuyang; Wang, Ranran; Wu, Qiang; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Cheng, Yajun; Chu, Haibin

2016-07-01

In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter.

Tension-controlled single-crystallization of copper foils for roll-to-roll synthesis of high-quality graphene films

Science.gov (United States)

Jo, Insu; Park, Subeom; Kim, Dongjin; San Moon, Jin; Park, Won Bae; Kim, Tae Hyeong; Hyoun Kang, Jin; Lee, Wonbae; Kim, Youngsoo; Lee, Dong Nyung; Cho, Sung-Pyo; Choi, Hyunchul; Kang, Inbyeong; Park, Jong Hyun; Lee, Jeong Soo; Hong, Byung Hee

2018-04-01

It has been known that the crystalline orientation of Cu substrates plays a crucial role in chemical vapor deposition (CVD) synthesis of high-quality graphene. In particular, Cu (1 1 1) surface showing the minimum lattice mismatch with graphene is expected to provide an ideal catalytic reactivity that can minimize the formation of defects, which also induces larger single-crystalline domain sizes of graphene. Usually, the Cu (1 1 1) substrates can be epitaxially grown on single-crystalline inorganic substrates or can be recrystallized by annealing for more than 12 h, which limits the cost and time-effective synthesis of graphene. Here, we demonstrate a new method to optimize the crystalline orientations of vertically suspended Cu foils by tension control during graphene growth, resulting in large-area recrystallization into Cu (1 1 1) surface as the applied tension activates the grain boundary energy of Cu and promotes its abnormal grain growth to single crystals. In addition, we found a clue that the formation of graphene cooperatively assists the recrystallization into Cu (1 1 1) by minimizing the surface energy of Cu. The domain sizes and charge carrier mobility of graphene grown on the single-crystalline Cu (1 1 1) are 5 times and ~50% increased, respectively, in comparison with those of graphene from Cu (1 0 0), indicating that the less lattice mismatch and the lower interaction energy between Cu (1 1 1) and graphene allows the growth of larger single-crystalline graphene with higher charge carrier mobility. Thus, we believe that our finding provides a crucial idea to design a roll-to-roll (R2R) graphene synthesis system where the tension control is inevitably involved, which would be of great importance for the continuous production of high-quality graphene in the future.

Low-Temperature and Rapid Growth of Large Single-Crystalline Graphene with Ethane.

Science.gov (United States)

Sun, Xiao; Lin, Li; Sun, Luzhao; Zhang, Jincan; Rui, Dingran; Li, Jiayu; Wang, Mingzhan; Tan, Congwei; Kang, Ning; Wei, Di; Xu, H Q; Peng, Hailin; Liu, Zhongfan

2018-01-01

Future applications of graphene rely highly on the production of large-area high-quality graphene, especially large single-crystalline graphene, due to the reduction of defects caused by grain boundaries. However, current large single-crystalline graphene growing methodologies are suffering from low growth rate and as a result, industrial graphene production is always confronted by high energy consumption, which is primarily caused by high growth temperature and long growth time. Herein, a new growth condition achieved via ethane being the carbon feedstock to achieve low-temperature yet rapid growth of large single-crystalline graphene is reported. Ethane condition gives a growth rate about four times faster than methane, achieving about 420 µm min -1 for the growth of sub-centimeter graphene single crystals at temperature about 1000 °C. In addition, the temperature threshold to obtain graphene using ethane can be reduced to 750 °C, lower than the general growth temperature threshold (about 1000 °C) with methane on copper foil. Meanwhile ethane always keeps higher graphene growth rate than methane under the same growth temperature. This study demonstrates that ethane is indeed a potential carbon source for efficient growth of large single-crystalline graphene, thus paves the way for graphene in high-end electronical and optoelectronical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CVD synthesis of large-area, highly crystalline MoSe2 atomic layers on diverse substrates and application to photodetectors.

Science.gov (United States)

Xia, Jing; Huang, Xing; Liu, Ling-Zhi; Wang, Meng; Wang, Lei; Huang, Ben; Zhu, Dan-Dan; Li, Jun-Jie; Gu, Chang-Zhi; Meng, Xiang-Min

2014-08-07

Synthesis of large-area, atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for the large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly-crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates using a simple chemical vapour deposition (CVD) method at atmospheric pressure. Atomic force microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ∼ 1.56 eV, indicating the transition from an indirect to a direct bandgap. Transmission electron microscopy (TEM) analysis confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, the photoresponse performance of photodetectors based on MoSe2 monolayer was studied for the first time. The devices exhibit a rapid response of ∼ 60 ms and a good photoresponsivity of ∼ 13 mA/W (using a 532 nm laser at an intensity of 1 mW mm(-2) and a bias of 10 V), suggesting that MoSe2 monolayer is a promising material for photodetection applications.

Titanium carbide nanocube core induced interfacial growth of crystalline polypyrrole/polyvinyl alcohol lamellar shell for wide-temperature range supercapacitors

Science.gov (United States)

Weng, Yu-Ting; Pan, Hsiao-An; Wu, Nae-Lih; Chen, Geroge Zheng

2015-01-01

This is the first investigation on electrically conducting polymers-based supercapacitor electrodes over a wide temperature range, from -18 °C to 60 °C. A high-performance supercapacitor electrode material consisting of TiC nanocube core and conformal crystalline polypyrrole (PPy)/poly-vinyl-alcohol (PVA) lamellar shell has been synthesized by heterogeneous nucleation-induced interfacial crystallization. PPy is induced to crystallize on the negatively charged TiC nanocube surfaces via strong interfacial interactions. In this organic-inorganic hybrid nanocomposite, the long chain PVA enables enhanced cycle life due to improved mechanical properties, and the TiC nanocube not only contributes to electron conduction, but also dictates the PPy morphology/crystallinity for maximizing the charging-discharging performance. The crystalline PPy/PAV layer on the TiC nanocube offers unprecedented high capacity (>350 F g-1-PPy at 300 mV s-1 with ΔV = 1.6 V) and cycling stability in a temperature range from -18 °C to 60 °C. The presented hybrid-filler and interfacial crystallization strategies can be applied to the exploration of new-generation high-power conducting polymer-based supercapacitor materials.

The new concept of hyphenated analytical system: Simultaneous determination of inorganic arsenic(III), arsenic(V), selenium(IV) and selenium(VI) by high performance liquid chromatography-hydride generation-(fast sequential) atomic absorption spectrometry during single analysis

International Nuclear Information System (INIS)

Niedzielski, P.

2005-01-01

The paper presents a new conception of determination of inorganic speciation forms of arsenic: As(III) and As(V) as well selenium Se(IV) and Se(VI) by means of the high performance liquid chromatography hyphenated with a detection by the atomic absorption spectrometry with hydride generation (HPLC-HG-AAS). The application of optimization procedure conditions of chromatographic separation of arsenic and selenium speciation forms (using anion-exchange Supelco LC-SAX1 column and phosphate buffer at pH 5.40 as a mobile phase) as well as the use of the atomic absorption spectrometry as a detector, which enables work in fast sequential mode, allowed to develop original detection methodology of simultaneous determination of arsenic As(III), As(V) and selenium Se(IV) and Se(VI) speciation forms within a 220 s single analysis. The obtained detection limits were 7.8 ng mL -1 for As(III); 12.0 ng mL -1 for As(V); 2.4 ng mL -1 for Se(IV) and 18.6 ng mL -1 for Se(VI) and precision 10.5%, 12.1%, 14.2% and 17.3%, respectively, for 100 ng mL -1 . The described method was used for ground water analysis

Investigation of the separation of americium(III) and europium(III) by high-speed countercurrent chromatography

International Nuclear Information System (INIS)

Wu, J.F.; Jin, Y.R.; Xu, Q.C.; Wang, S.L.; Zhang, L.X.

2005-01-01

The long-lived actinides are the important elements in the radioactive waste ;disposal. Because the ions semi diameter and chemical properties of trivalent actinides(III) and trivalent lanthanides(III) are very similar, the separation between them is very difficult. Yang Yu-Sheng put forward the actinides(III) are softer acid than the lanthanides(III), so the actinides(III) are more easily extracted by the soft extractant contain sulfur or nitrogen than the lanthanides(III). Some research have been done on the separation between actinides(III) and lanthanides(III) using the extractants contain sulfur or nitrogen. The results show that satisfactory separation efficiency was gained. Countercurrent Chromatography (CCC) have many specific advantages, such as free from solid support, permit large sample volume and high flow rate, which is useful in the preconcentration of inorganic solute and inorganic preparation. Some studies were done on the separation of lanthanides or-other inorganic elements by HSCCC, the high-purity reagents prepared by HSCCC or CPC turned out to be successful. In present paper, the investigation of separation between Americium (III) and Euricium (III) by High-Speed Countercurrent Chromatography (HSCCC) were made. The extractant used in the work was prepared by ourselves, which is of the soft extractant contrain sulfur. The effects of separation condition on the separation efficiency of Am and Eu by HSCCC were investigated using dichlorophenyl dithiophosphinic acid in xylene as the stationary phase and 0.1 mol/L NaClO4 as mobile phase, respectively. The results show that mutual separation between Am and Eu can be accomplished. The separation factor increases with the increasing of the concentration of extractant and the pH value of the mobile phase, further more, minishing the flow rate of the mobile phase can also improves the separation efficiency between Am and Eu. The nearly base separation was gained when the flow rate is 0.35 ml/min, the

Microwave-assisted preparation of Li3V2(PO4)3/C composite with high-rate capacity

International Nuclear Information System (INIS)

Yan, Ji; Mao, Wen-feng; Xie, Hui; Tang, Zhi-yuan; Yuan, Wei; Chen, Xue-cheng; Xu, Qiang; Ma, Li

2012-01-01

Highlights: ► High-rate Li 3 V 2 (PO 4 ) 3 /C is firstly reported via a microwave-assisted method. ► The reduced particle size is responsible for the improved high-rate performance. ► A discharge capacity of 100 mAh g −1 is obtained at 20 C charge–discharge rate. -- Abstract: A fast sol–gel assisted microwave heating approach has been developed for the synthesis of high-rate Li 3 V 2 (PO 4 ) 3 /C cathode material. This approach can synthesize Li 3 V 2 (PO 4 ) 3 /C particles with high purity and good crystallinity in 12 min at a low microwave power of 320 W. In the voltage range of 3.0–4.3 V, the obtained Li 3 V 2 (PO 4 ) 3 /C delivers a reversible discharge capacity of 100 mAh g −1 after 100 cycles at 20 °C, exhibiting excellent rate capability and cycling performance. The rate-recovery performance also suggests that the Li 3 V 2 (PO 4 ) 3 /C material possesses excellent structure stability after high-rate cycles, presenting excellent application value in high-power lithium ion batteries.

Highly Crystalline C8-BTBT Thin-Film Transistors by Lateral Homo-Epitaxial Growth on Printed Templates.

Science.gov (United States)

Janneck, Robby; Pilet, Nicolas; Bommanaboyena, Satya Prakash; Watts, Benjamin; Heremans, Paul; Genoe, Jan; Rolin, Cedric

2017-11-01

Highly crystalline thin films of organic semiconductors offer great potential for fundamental material studies as well as for realizing high-performance, low-cost flexible electronics. The fabrication of these films directly on inert substrates is typically done by meniscus-guided coating techniques. The resulting layers show morphological defects that hinder charge transport and induce large device-to-device variability. Here, a double-step method for organic semiconductor layers combining a solution-processed templating layer and a lateral homo-epitaxial growth by a thermal evaporation step is reported. The epitaxial regrowth repairs most of the morphological defects inherent to meniscus-guided coatings. The resulting film is highly crystalline and features a mobility increased by a factor of three and a relative spread in device characteristics improved by almost half an order of magnitude. This method is easily adaptable to other coating techniques and offers a route toward the fabrication of high-performance, large-area electronics based on highly crystalline thin films of organic semiconductors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen-mediated Nitrogen Clustering in Dilute III-V Nitrides

Energy Technology Data Exchange (ETDEWEB)

Du, M.-H.; Limpijumnong, S.; Zhang, S. B

2006-01-01

First-principles calculation reveals multi-N clusters to be the ground states for hydrogenated N in dilute III-V nitrides. While hydrogenation of a single N, forming H*{sub 2}(N), can relax the large strain induced by the size-mismatched N, formation of the clusters will relax the strain even more effectively. This suppresses the formation of H*{sub 2}(N), the existence of which has recently been debated. More importantly, postgrowth dehydrogenation of the N-H clusters provides an explanation to the observed metastable bare N clusters in GaAsN grown by gas-source molecular beam epitaxy or metal-organic chemical vapor deposition.

Hydrogen-Mediated Nitrogen Clustering in Dilute III-V Nitrides

Science.gov (United States)

Du, Mao-Hua; Limpijumnong, Sukit; Zhang, S. B.

2006-08-01

First-principles calculation reveals multi-N clusters to be the ground states for hydrogenated N in dilute III-V nitrides. While hydrogenation of a single N, forming H2*(N), can relax the large strain induced by the size-mismatched N, formation of the clusters will relax the strain even more effectively. This suppresses the formation of H2*(N), the existence of which has recently been debated. More importantly, postgrowth dehydrogenation of the N-H clusters provides an explanation to the observed metastable bare N clusters in GaAsN grown by gas-source molecular beam epitaxy or metal-organic chemical vapor deposition.

High-Temperature Growth of GaN and Al x Ga1- x N via Ammonia-Based Metalorganic Molecular-Beam Epitaxy

Science.gov (United States)

Billingsley, Daniel; Henderson, Walter; Doolittle, W. Alan

2010-05-01

The effect of high-temperature growth on the crystalline quality and surface morphology of GaN and Al x Ga1- x N grown by ammonia-based metalorganic molecular-beam epitaxy (NH3-MOMBE) has been investigated as a means of producing atomically smooth films suitable for device structures. The effects of V/III ratio on the growth rate and surface morphology are described herein. The crystalline quality of both GaN and AlGaN was found to mimic that of the GaN templates, with (002) x-ray diffraction (XRD) full-widths at half- maximum (FWHMs) of ~350 arcsec. Nitrogen-rich growth conditions have been found to provide optimal surface morphologies with a root-mean-square (RMS) roughness of ~0.8 nm, yet excessive N-rich environments have been found to reduce the growth rate and result in the formation of faceted surface pitting. AlGaN exhibits a decreased growth rate, as compared with GaN, due to increased N recombination as a result of the increased pyrolysis of NH3 in the presence of Al. AlGaN films grown directly on GaN templates exhibited Pendellösung x-ray fringes, indicating an abrupt interface and a planar AlGaN film. AlGaN films grown for this study resulted in an optimal RMS roughness of ~0.85 nm with visible atomic steps.

Machine-learning approach for local classification of crystalline structures in multiphase systems

Science.gov (United States)

Dietz, C.; Kretz, T.; Thoma, M. H.

2017-07-01

Machine learning is one of the most popular fields in computer science and has a vast number of applications. In this work we will propose a method that will use a neural network to locally identify crystal structures in a mixed phase Yukawa system consisting of fcc, hcp, and bcc clusters and disordered particles similar to plasma crystals. We compare our approach to already used methods and show that the quality of identification increases significantly. The technique works very well for highly disturbed lattices and shows a flexible and robust way to classify crystalline structures that can be used by only providing particle positions. This leads to insights into highly disturbed crystalline structures.

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

Energy Technology Data Exchange (ETDEWEB)

Mishra, A; Singh, M P; Singh, V K

1982-05-01

The nitrato-complexes, (Y(PyBzH)/sub 2/(NO/sub 3/)/sub 2/)NO/sub 3/.H/sub 2/O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole) are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm/sup -1/cm/sup 2/mol/sup -1/) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the positive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C/sub 2/v) and uncoordinated (D/sub 3/h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms.

Nitrato-complexes of Y(III), La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III) and Ho(III) with 2-(2'-pyridyl) benzimidazole

International Nuclear Information System (INIS)

Mishra, A.; Singh, M.P.; Singh, V.K.

1982-01-01

The nitrato-complexes, [Y(PyBzH) 2 (NO 3 ) 2 ]NO 3 .H 2 O and Nd, Sm, Gd, Tb, Dy, Ho ; n=1-3, m=0-0.5 ; PyBzh=2-(2 -pyridyl)benzimidazole] are formed on interaction of the ligand with metal nitrates in ethanol. The electrical conductance values (116-129 ohm -1 cm 2 mol -1 ) suggest 1:1 electrolyte-nature of the complexes. Magnetic moment values of Ce(2.53 B.M.), Pr(3.62 B.M.), Nd(3.52 B.M.), Sm(1.70 B.M.), Gd(8.06 B.M.), Tb(9.44 B.M.), Dy(10.56 B.M.) and Ho(10.51 B.M.) in the complexes confirm the terpositive state of the metals. Infrared evidences are obtained for the existance of both coordinated (C 2 v) and uncoordinated (D 3 h) nitrate groups. Electronic absorption spectra of Pr(III)-, Nd(III)-, Sm(III)-, Tb(III)-, Dy(III)- and Ho(III)-complexes have been analysed in the light of LSJ terms. (author)

Specific heat of Nb3Sn and V2Zr compounds irradiated with high fluences fast neutrons

International Nuclear Information System (INIS)

Kar'kin, A.E.; Mirmel'shtejn, A.V.; Arkhipov, V.E.; Goshchitskij, B.N.

1987-01-01

Specific heat of Nb 3 Sn (structure A15) and V 2 Zr (C15) specimens irradiated with high fluences of bast neutrons has been measured. It is shown that in these compounds the temperature reduction of superconducting transition T c under neutron irradiation is accompanied with high decrease of N(E F ). Phonon spectrum of the irradiated V 2 Zr (amorphous phase) on the whole is harder, than at an initial state, for irradiated Nb 3 Sn state (disordered crystalline structure) phonon spectrum is differ weakly from initial one. General regularities of parameter change of electron and phonon subsystems for A15 compounds investigated here and earlier (V 3 Si, Mo 3 Si, Mo 3 Ge) have been analysed

Separation of uranium(V I) from binary solution mixtures with thorium(IV), zirconium(IV) and cerium(III) by foaming

International Nuclear Information System (INIS)

Shakir, K.; Aziz, M.; Benyamin, K.

1992-01-01

Foam separation has been investigated for the removal of uranium(V I), thorium(IV), zirconium(IV) and cerium(III) from dilute aqueous solutions at pH values ranging from about I to about II. Sodium laurel sulphate (Na L S) and acetyl trimethyl ammonium bromide (CTAB), being a strong anionic and a strong cationic surfactants, were used as collectors. The results indicate that Na L S can efficiently remove thorium(IV), zirconium(IV) and cerium(III) but not uranium(V I). CTAB, on the other hand, can successfully float only uranium(V I) and zirconium(IV). These differences in flotation properties of the different cations could be used to establish methods for the separation of uranium(V I) from binary mixtures with thorium(IV), zirconium(IV) or cerium(III). The results are discussed in terms of the hydrolytic behaviour of the tested cations and properties of used collectors.2 fig., 1 tab

Highly crystalline mesoporous C{sub 60} with ordered pores. A class of nanomaterials for energy applications

Energy Technology Data Exchange (ETDEWEB)

Benzigar, Mercy R.; Joseph, Stalin; Ilbeygi, Hamid [Future Industries Institute (FII), Division of Information Technology Energy and Environment (DivITEE), University of South Australia, Adelaide, SA (Australia); Park, Dae-Hwan; Talapaneni, Siddulu Naidu [Global Innovative Center for Advanced Nanomaterials (GICAN), Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW (Australia); Sarkar, Sujoy; Chandra, Goutam; Umapathy, Siva; Srinivasan, Sampath [Department of Inorganic and Physical Chemistry and Department of Instrumentation and Applied Physics, Indian Institute of Science (IISc), Bangalore (India); Vinu, Ajayan [Future Industries Institute (FII), Division of Information Technology Energy and Environment (DivITEE), University of South Australia, Adelaide, SA (Australia); Global Innovative Center for Advanced Nanomaterials (GICAN), Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW (Australia)

2018-01-08

Highly ordered mesoporous C{sub 60} with a well-ordered porous structure and a high crystallinity is prepared through the nanohard templating method using a saturated solution of C{sub 60} in 1-chloronaphthalene (51 mg mL{sup -1}) as a C{sub 60} precursor and SBA-15 as a hard template. The high solubility of C{sub 60} in 1-chloronaphthalene helps not only to encapsulate a huge amount of the C{sub 60} into the mesopores of the template but also supports the oligomerization of C{sub 60} and the formation of crystalline walls made of C{sub 60}. The obtained mesoporous C{sub 60} exhibits a rod-shaped morphology, a high specific surface area (680 m{sup 2} g{sup -1}), tuneable pores, and a highly crystalline wall structure. This exciting ordered mesoporous C{sub 60} offers high supercapacitive performance and a high selectivity to H{sub 2}O{sub 2} production and methanol tolerance for ORR. This simple strategy could be adopted to make a series of mesoporous fullerenes with different structures and carbon atoms as a new class of energy materials. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Scalable Directed Assembly of Highly Crystalline 2,7-Dioctyl[1]benzothieno[3,2- b][1]benzothiophene (C8-BTBT) Films.

Science.gov (United States)

Chai, Zhimin; Abbasi, Salman A; Busnaina, Ahmed A

2018-05-30

Assembly of organic semiconductors with ordered crystal structure has been actively pursued for electronics applications such as organic field-effect transistors (OFETs). Among various film deposition methods, solution-based film growth from small molecule semiconductors is preferable because of its low material and energy consumption, low cost, and scalability. Here, we show scalable and controllable directed assembly of highly crystalline 2,7-dioctyl[1]benzothieno[3,2- b][1]benzothiophene (C8-BTBT) films via a dip-coating process. Self-aligned stripe patterns with tunable thickness and morphology over a centimeter scale are obtained by adjusting two governing parameters: the pulling speed of a substrate and the solution concentration. OFETs are fabricated using the C8-BTBT films assembled at various conditions. A field-effect hole mobility up to 3.99 cm 2 V -1 s -1 is obtained. Owing to the highly scalable crystalline film formation, the dip-coating directed assembly process could be a great candidate for manufacturing next-generation electronics. Meanwhile, the film formation mechanism discussed in this paper could provide a general guideline to prepare other organic semiconducting films from small molecule solutions.

Study of III-V semiconductor band structure by synchrotron photoemission

International Nuclear Information System (INIS)

Williams, G.P.; Cerrina, F.; Anderson, J.; Lapeyre, G.J.; Smith, R.J.; Hermanson, J.; Knapp, J.A.

1982-01-01

Angle-resolved synchrotron photoemission studies of six III-V semiconductors have been carried out. For emission normal to the (110) plane of these materials, peaks in the experimental spectra were identified with the bands involved in the transitions, and the critical point energies X 3 , X 5 , and Σ 1 /sup min/, were determined. The data indicate that k perpendicular is conserved in the transitions. Comparison of the data with theoretical bands permits an evaluation of k perpendicular associated with the experimentally observed transition, and from this information the bands were plotted out

Sparkle/PM3 for the modeling of europium(III), gadolinium(III), and terbium(III) complexes

International Nuclear Information System (INIS)

Freire, Ricardo O.; Rocha, Gerd B.; Simas, Alfredo M.

2009-01-01

The Sparkle/PM3 model is extended to europium(III), gadolinium(III), and terbium(III) complexes. The validation procedure was carried out using only high quality crystallographic structures, for a total of ninety-six Eu(III) complexes, seventy Gd(III) complexes, and forty-two Tb(III) complexes. The Sparkle/PM3 unsigned mean error, for all interatomic distances between the trivalent lanthanide ion and the ligand atoms of the first sphere of coordination, is: 0.080 A for Eu(III); 0.063 A for Gd(III); and 0.070 A for Tb(III). These figures are similar to the Sparkle/AM1 ones of 0.082 A, 0.061 A, and 0.068 A respectively, indicating they are all comparable parameterizations. Moreover, their accuracy is similar to what can be obtained by present-day ab initio effective core potential full geometry optimization calculations on such lanthanide complexes. Finally, we report a preliminary attempt to show that Sparkle/PM3 geometry predictions are reliable. For one of the Eu(III) complexes, BAFZEO, we created hundreds of different input geometries by randomly varying the distances and angles of the ligands to the central Eu(III) ion, which were all subsequently fully optimized. A significant trend was unveiled, indicating that more accurate local minima geometries cluster at lower total energies, thus reinforcing the validity of sparkle model calculations. (author)

Guiding principle for crystalline Si photovoltaic modules with high tolerance to acetic acid

Science.gov (United States)

Masuda, Atsushi; Hara, Yukiko

2018-04-01

A guiding principle for highly reliable crystalline Si photovoltaic modules, especially those with high tolerance to acetic acid generated by hydrolysis reaction between water vapor and an ethylene-vinyl acetate (EVA) encapsulant, is proposed. Degradation behavior evaluated by the damp heat test strongly depends on Ag finger electrodes and also EVA encapsulants. The acetic acid concentration in EVA on the glass side directly determines the degradation behavior. The most important factor for high tolerance is the type of Ag finger electrode materials when using an EVA encapsulant. Photovoltaic modules using newly developed crystalline Si cells with improved Ag finger electrode materials keep their maximum power of 80% of the initial value even after the damp heat test at 85 °C and 85% relative humidity for 10000 h. The pattern of dark regions in electroluminescence images is also discussed on the basis of the dynamics of acetic acid in the modules.

Phonon and free-charge carrier properties in group-III nitride heterostructures investigated by spectroscopic ellipsometry and optical Hall effect

Science.gov (United States)

Schoeche, Stefan

The material class of group-III nitrides gained tremendous technological importance for optoelectronic and high-power/high-frequency amplification devices. Tunability of the direct band gap from 0.65 eV (InN) to 6.2 eV (AlN) by alloying, high breakthrough voltages and intrinsic mobilities, as well as the formation of highly mobile 2d electron gases (2DEG) at heterointerfaces make these compounds ideal for many applications. GaN and Ga-rich alloys are well studied and current research is mainly device-oriented. For example, choice and quality of the gate dielectric significantly influence device performance in high-electron mobility transistors (HEMT) which utilize highly mobile 2DEGs at heterointerfaces. Experimental access to the 2DEG channel properties without influence from parasitic currents or contact properties are desirable. In- and Al-rich ternary alloys are less explored than Ga-rich compounds. For InN and In-rich alloys, while many material parameters such as stiffness constants or effective mass values are largely unknown, reliable p-type doping is a major challenge, also because p-type conducting channels are buried within highly conductive n-type material formed at the surface and interfaces preventing electrical characterization. For AlN and high-Al content alloys, doping mechanisms are not understood and reliable fabrication of material with high free-charge carrier (FCC) concentrations was achieved just recently. Difficulties to form ohmic contacts impair electrical measurements and optical characterization is impeded by lack of high-energy excitation sources. In this work, spectroscopic ellipsometry over the wide spectral range from the THz to VUV in combination with optical Hall effect (generalized ellipsometry with applied magnetic field) from THz to MIR are applied in order to investigate the phonon modes and FCC properties in group-III nitride heterostructures. Adequate model descriptions and analysis strategies are introduced which allow

Crystalline and amorphous rare-earth metallic compounds

International Nuclear Information System (INIS)

Burzo, E.

1975-01-01

During the last years the study of magnetic behaviour of rare-earth (or yttrium) compounds with cobalt and iron has growth of interest. This interest of justified by a large area of experimental and theoretical problems coming into being in the study of some rare-earth materials as well as in their technical applications. In the last three years a great number of new rare earth materials were studied and also new models explaining the magnetic behaviour of these systems have been used. In this paper we refer especially to some typical systems in order to analyse the magnetic behaviour of iron and cobalt and also the part played by the magnetic interactions in the values of the cobalt or iron moments. The model used will be generally the molecular field model. In the second chapter we present comparatively the structure of crystalline and amorphous compounds for further correlation with the magnetic properties. In chapter III we analyse the magnetic interactions in some crystalline and amorphous rare-earth alloys. Finally, we exemplify the ways in which we ensure better requried characteristics by the technical utilizations of these materials. These have in view the modifications of the magnetic interactions and are closely related with the analysis made in chapter III

Hybrid III-V on Si grating as a broadband reflector and a high-Q resonator

DEFF Research Database (Denmark)

Chung, Il-Sug; Taghizadeh, Alireza; Park, Gyeong Cheol

2016-01-01

Hybrid grating (HG) with a high-refractive-index cap layer added onto a high contrast grating (HCG), can provide a high reflectance close 100 % over a broader wavelength range than HCGs, or work as a ultrahigh quality (Q) factor resonator. The reflection and resonance properties of HGs have been...

Laterally inherently thin amorphous-crystalline silicon heterojunction photovoltaic cell

Energy Technology Data Exchange (ETDEWEB)

Chowdhury, Zahidur R., E-mail: zr.chowdhury@utoronto.ca; Kherani, Nazir P., E-mail: kherani@ecf.utoronto.ca [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada)

2014-12-29

This article reports on an amorphous-crystalline silicon heterojunction photovoltaic cell concept wherein the heterojunction regions are laterally narrow and distributed amidst a backdrop of well-passivated crystalline silicon surface. The localized amorphous-crystalline silicon heterojunctions consisting of the laterally thin emitter and back-surface field regions are precisely aligned under the metal grid-lines and bus-bars while the remaining crystalline silicon surface is passivated using the recently proposed facile grown native oxide–plasma enhanced chemical vapour deposited silicon nitride passivation scheme. The proposed cell concept mitigates parasitic optical absorption losses by relegating amorphous silicon to beneath the shadowed metallized regions and by using optically transparent passivation layer. A photovoltaic conversion efficiency of 13.6% is obtained for an untextured proof-of-concept cell illuminated under AM 1.5 global spectrum; the specific cell performance parameters are V{sub OC} of 666 mV, J{sub SC} of 29.5 mA-cm{sup −2}, and fill-factor of 69.3%. Reduced parasitic absorption, predominantly in the shorter wavelength range, is confirmed with external quantum efficiency measurement.

Organic / IV, III-V Semiconductor Hybrid Solar Cells

Directory of Open Access Journals (Sweden)

Pang-Leen Ong

2010-03-01

Full Text Available We present a review of the emerging class of hybrid solar cells based on organic-semiconductor (Group IV, III-V, nanocomposites, which states separately from dye synthesized, polymer-metal oxides and organic-inorganic (Group II-VI nanocomposite photovoltaics. The structure of such hybrid cell comprises of an organic active material (p-type deposited by coating, printing or spraying technique on the surface of bulk or nanostructured semiconductor (n-type forming a heterojunction between the two materials. Organic components include various photosensitive monomers (e.g., phtalocyanines or porphyrines, conjugated polymers, and carbon nanotubes. Mechanisms of the charge separation at the interface and their transport are discussed. Also, perspectives on the future development of such hybrid cells and comparative analysis with other classes of photovoltaics of third generation are presented.

Effects of V2O3 buffer layers on sputtered VO2 smart windows: Improved thermochromic properties, tunable width of hysteresis loops and enhanced durability

Science.gov (United States)

Long, Shiwei; Cao, Xun; Sun, Guangyao; Li, Ning; Chang, Tianci; Shao, Zewei; Jin, Ping

2018-05-01

Vanadium dioxide (VO2) is one of the most well-known thermochromic materials, which exhibits a notable optical change from transparent to reflecting in the infrared region upon a metal-insulator phase transition. For practical applications, VO2 thin films should be in high crystalline quality to obtain a strong solar modulation ability (ΔTsol). Meanwhile, narrow hysteresis loops and robust ambient durability are also indispensable for sensitivity and long-lived utilization, respectively. In this work, a series of high-quality V2O3/VO2 bilayer structures were grown on quartz glass substrates by reactive magnetron sputtering. Basically, the bottom V2O3 acts as the buffer layer to improve the crystallinity of the top VO2, while the VO2 serves as the thermochromic layer to guarantee the solar modulation ability for energy-saving. We observed an obvious increase in ΔTsol of 76% (from 7.5% to 13.2%) for VO2 films after introducing V2O3 buffer layers. Simultaneously, a remarkable reduction by 79% (from 21.9 °C to 4.7 °C) in width of hysteresis loop was obtained when embedding 60 nm V2O3 buffer for 60 nm VO2. In addition, VO2 with non-stoichiometry of V2O3±x buffer demonstrates a broadening hysteresis loops width, which is derived from the lattice distortion caused by lattice imperfection. Finally, durability of VO2 has been significantly improved due to positive effects of V2O3 buffer layer. Our results lead to a comprehensive enhancement in crystallinity of VO2 and shed new light on the promotion of thermochromic property by homologous oxides for VO2.

Optical analysis of a III-V-nanowire-array-on-Si dual junction solar cell.

Science.gov (United States)

Chen, Yang; Höhn, Oliver; Tucher, Nico; Pistol, Mats-Erik; Anttu, Nicklas

2017-08-07

A tandem solar cell consisting of a III-V nanowire subcell on top of a planar Si subcell is a promising candidate for next generation photovoltaics due to the potential for high efficiency. However, for success with such applications, the geometry of the system must be optimized for absorption of sunlight. Here, we consider this absorption through optics modeling. Similarly, as for a bulk dual-junction tandem system on a silicon bottom cell, a bandgap of approximately 1.7 eV is optimum for the nanowire top cell. First, we consider a simplified system of bare, uncoated III-V nanowires on the silicon substrate and optimize the absorption in the nanowires. We find that an optimum absorption in 2000 nm long nanowires is reached for a dense array of approximately 15 nanowires per square micrometer. However, when we coat such an array with a conformal indium tin oxide (ITO) top contact layer, a substantial absorption loss occurs in the ITO. This ITO could absorb 37% of the low energy photons intended for the silicon subcell. By moving to a design with a 50 nm thick, planarized ITO top layer, we can reduce this ITO absorption to 5%. However, such a planarized design introduces additional reflection losses. We show that these reflection losses can be reduced with a 100 nm thick SiO 2 anti-reflection coating on top of the ITO layer. When we at the same time include a Si 3 N 4 layer with a thickness of 90 nm on the silicon surface between the nanowires, we can reduce the average reflection loss of the silicon cell from 17% to 4%. Finally, we show that different approximate models for the absorption in the silicon substrate can lead to a 15% variation in the estimated photocurrent density in the silicon subcell.

Trends in heteroepitaxy of III-Vs on silicon for photonic and photovoltaic applications

Science.gov (United States)

Lourdudoss, Sebastian; Junesand, Carl; Kataria, Himanshu; Metaferia, Wondwosen; Omanakuttan, Giriprasanth; Sun, Yan-Ting; Wang, Zhechao; Olsson, Fredrik

2017-02-01

We present and compare the existing methods of heteroepitaxy of III-Vs on silicon and their trends. We focus on the epitaxial lateral overgrowth (ELOG) method as a means of achieving good quality III-Vs on silicon. Initially conducted primarily by near-equilibrium epitaxial methods such as liquid phase epitaxy and hydride vapour phase epitaxy, nowadays ELOG is being carried out even by non-equilibrium methods such as metal organic vapour phase epitaxy. In the ELOG method, the intermediate defective seed and the mask layers still exist between the laterally grown purer III-V layer and silicon. In a modified ELOG method called corrugated epitaxial lateral overgrowth (CELOG) method, it is possible to obtain direct interface between the III-V layer and silicon. In this presentation we exemplify some recent results obtained by these techniques. We assess the potentials of these methods along with the other existing methods for realizing truly monolithic photonic integration on silicon and III-V/Si heterojunction solar cells.

Microscopic theory of singlet exciton fission. III. Crystalline pentacene

International Nuclear Information System (INIS)

Berkelbach, Timothy C.; Reichman, David R.; Hybertsen, Mark S.

2014-01-01

We extend our previous work on singlet exciton fission in isolated dimers to the case of crystalline materials, focusing on pentacene as a canonical and concrete example. We discuss the proper interpretation of the character of low-lying excited states of relevance to singlet fission. In particular, we consider a variety of metrics for measuring charge-transfer character, conclusively demonstrating significant charge-transfer character in the low-lying excited states. The impact of this electronic structure on the subsequent singlet fission dynamics is assessed by performing real-time master-equation calculations involving hundreds of quantum states. We make direct comparisons with experimental absorption spectra and singlet fission rates, finding good quantitative agreement in both cases, and we discuss the mechanistic distinctions that exist between small isolated aggregates and bulk systems

Microscopic theory of singlet exciton fission. III. Crystalline pentacene

Energy Technology Data Exchange (ETDEWEB)

Berkelbach, Timothy C., E-mail: tcb2112@columbia.edu; Reichman, David R., E-mail: drr2103@columbia.edu [Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 (United States); Hybertsen, Mark S., E-mail: mhyberts@bnl.gov [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

2014-08-21

We extend our previous work on singlet exciton fission in isolated dimers to the case of crystalline materials, focusing on pentacene as a canonical and concrete example. We discuss the proper interpretation of the character of low-lying excited states of relevance to singlet fission. In particular, we consider a variety of metrics for measuring charge-transfer character, conclusively demonstrating significant charge-transfer character in the low-lying excited states. The impact of this electronic structure on the subsequent singlet fission dynamics is assessed by performing real-time master-equation calculations involving hundreds of quantum states. We make direct comparisons with experimental absorption spectra and singlet fission rates, finding good quantitative agreement in both cases, and we discuss the mechanistic distinctions that exist between small isolated aggregates and bulk systems.

Study of conformational changes and protein aggregation of bovine serum albumin in presence of Sb(III) and Sb(V).

Science.gov (United States)

Verdugo, Marcelo; Ruiz Encinar, Jorge; Costa-Fernández, José Manuel; Menendez-Miranda, Mario; Bouzas-Ramos, Diego; Bravo, Manuel; Quiroz, Waldo

2017-01-01

Antimony is a metalloid that affects biological functions in humans due to a mechanism still not understood. There is no doubt that the toxicity and physicochemical properties of Sb are strongly related with its chemical state. In this paper, the interaction between Sb(III) and Sb(V) with bovine serum albumin (BSA) was investigated in vitro by fluorescence spectroscopy, and circular dichroism (CD) under simulated physiological conditions. Moreover, the coupling of the separation technique, asymmetric flow field-flow fractionation, with elemental mass spectrometry to understand the interaction of Sb(V) and Sb(III) with the BSA was also used. Our results showed a different behaviour of Sb(III) vs. Sb(V) regarding their effects on the interaction with the BSA. The effects in terms of protein aggregates and conformational changes were higher in the presence of Sb(III) compared to Sb(V) which may explain the differences in toxicity between both Sb species in vivo. Obtained results demonstrated the protective effect of GSH that modifies the degree of interaction between the Sb species with BSA. Interestingly, in our experiments it was possible to detect an interaction between BSA and Sb species, which may be related with the presence of labile complex between the Sb and a protein for the first time.

High-rate synthesis of microcrystalline silicon films using high-density SiH4/H2 microwave plasma

International Nuclear Information System (INIS)

Jia, Haijun; Saha, Jhantu K.; Ohse, Naoyuki; Shirai, Hajime

2007-01-01

A high electron density (> 10 11 cm -3 ) and low electron temperature (1-2 eV) plasma is produced by using a microwave plasma source utilizing a spoke antenna, and is applied for the high-rate synthesis of high quality microcrystalline silicon (μc-Si) films. A very fast deposition rate of ∼ 65 A/s is achieved at a substrate temperature of 150 deg. C with a high Raman crystallinity and a low defect density of (1-2) x 10 16 cm -3 . Optical emission spectroscopy measurements reveal that emission intensity of SiH and intensity ratio of H α /SiH are good monitors for film deposition rate and film crystallinity, respectively. A high flux of film deposition precursor and atomic hydrogen under a moderate substrate temperature condition is effective for the fast deposition of highly crystallized μc-Si films without creating additional defects as well as for the improvement of film homogeneity

Microstructure, thermal properties and crystallinity of amadumbe starch nanocrystals.

Science.gov (United States)

Mukurumbira, Agnes; Mariano, Marcos; Dufresne, Alain; Mellem, John J; Amonsou, Eric O

2017-09-01

Amadumbe (Colocasia esculenta), commonly known as taro is a tropical tuber that produces starch-rich underground corms. In this study, the physicochemical properties of starch nanocrystals (SNC) prepared by acid hydrolysis of amadumbe starches were investigated. Two varieties of amadumbe corms were used for starch extraction. Amadumbe starches produced substantially high yield (25%) of SNC's. These nanocrystals appeared as aggregated and individual particles and possessed square-like platelet morphology with size: 50-100nm. FTIR revealed high peak intensities corresponding to OH stretch, CH stretch and H 2 O bending vibrations for SNCs compared to their native starch counterparts. Both the native starch and SNC exhibited the A-type crystalline pattern. However, amadumbe SNCs showed higher degree of crystallinity and slightly reduced melting temperatures than their native starches. Amadumbe SNCs presented similar thermal decomposition property as their native starches. Amadumbe starch nanocrystals may have potential application in biocomposite films due to their square-like platelet morphology. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of analytical techniques for characterization of crystalline clopidogrel forms in patent applications

Directory of Open Access Journals (Sweden)

Luiz Marcelo Lira

2014-04-01

Full Text Available The aim of this study was to evaluate two important aspects of patent applications of crystalline forms of drugs: (i the physicochemical characterization of the crystalline forms; and (ii the procedure for preparing crystals of the blockbuster drug clopidogrel. To this end, searches were conducted using online patent databases. The results showed that: (i the majority of patent applications for clopidogrel crystalline forms failed to comply with proposed Brazilian Patent Office guidelines. This was primarily due to insufficient number of analytical techniques evaluating the crystalline phase. In addition, some patent applications lacked assessment of chemical/crystallography purity; (ii use of more than two analytical techniques is important; and (iii the crystallization procedure for clopidogrel bisulfate form II were irreproducible based on the procedure given in the patent application.

Effect of a High Density of Stacking Faults on the Young's Modulus of GaAs Nanowires.

Science.gov (United States)

Chen, Yujie; Burgess, Tim; An, Xianghai; Mai, Yiu-Wing; Tan, H Hoe; Zou, Jin; Ringer, Simon P; Jagadish, Chennupati; Liao, Xiaozhou

2016-03-09

Stacking faults (SFs) are commonly observed crystalline defects in III-V semiconductor nanowires (NWs) that affect a variety of physical properties. Understanding the effect of SFs on NW mechanical properties is critical to NW applications in nanodevices. In this study, the Young's moduli of GaAs NWs with two distinct structures, defect-free single crystalline wurtzite (WZ) and highly defective wurtzite containing a high density of SFs (WZ-SF), are investigated using combined in situ compression transmission electron microscopy and finite element analysis. The Young's moduli of both WZ and WZ-SF GaAs NWs were found to increase with decreasing diameter due to the increasing volume fraction of the native oxide shell. The presence of a high density of SFs was further found to increase the Young's modulus by 13%. This stiffening effect of SFs is attributed to the change in the interatomic bonding configuration at the SFs.

Division III Collision Sports Are Not Associated with Neurobehavioral Quality of Life.

Science.gov (United States)

Meehan, William P; Taylor, Alex M; Berkner, Paul; Sandstrom, Noah J; Peluso, Mark W; Kurtz, Matthew M; Pascual-Leone, Alvaro; Mannix, Rebekah

2016-01-15

We sought to determine whether the exposure to the sub-concussive blows that occur during division III collegiate collision sports affect later life neurobehavioral quality-of-life measures. We conducted a cross-sectional study of alumni from four division III colleges, targeting those between the ages of 40-70 years, using several well-validated quality-of-life measures for executive function, general concerns, anxiety, depression, emotional and behavior dyscontrol, fatigue, positive affect, sleep disturbance, and negative consequences of alcohol use. We used multivariable linear regression to assess for associations between collision sport participation and quality-of-life measures while adjusting for covariates including age, gender, race, annual income, highest educational degree, college grades, exercise frequency, and common medical conditions. We obtained data from 3702 alumni, more than half of whom (2132) had participated in collegiate sports, 23% in collision sports, 23% in non-contact sports. Respondents with a history of concussion had worse self-reported health on several measures. When subjects with a history of concussion were removed from the analyses in order to assess for any potential effect of sub-concussive blows alone, negative consequences of alcohol use remained higher among collision sport athletes (β-coefficient 1.957, 95% CI 0.827-3.086). There were, however, no other significant associations between exposure to collision sports during college and any other quality-of-life measures. Our results suggest that, in the absence of a history of concussions, participation in collision sports at the Division III collegiate level is not a risk factor for worse long-term neurobehavioral outcomes, despite exposure to repeated sub-concussive blows.

Lateral topological crystalline insulator heterostructure

Science.gov (United States)

Sun, Qilong; Dai, Ying; Niu, Chengwang; Ma, Yandong; Wei, Wei; Yu, Lin; Huang, Baibiao

2017-06-01

The emergence of lateral heterostructures fabricated by two-dimensional building blocks brings many exciting realms in material science and device physics. Enriching available nanomaterials for creating such heterostructures and enabling the underlying new physics is highly coveted for the integration of next-generation devices. Here, we report a breakthrough in lateral heterostructure based on the monolayer square transition-metal dichalcogenides MX2 (M  =  W, X  =  S/Se) modules. Our results reveal that the MX2 lateral heterostructure (1S-MX2 LHS) can possess excellent thermal and dynamical stability. Remarkably, the highly desired two-dimensional topological crystalline insulator phase is confirmed by the calculated mirror Chern number {{n}\\text{M}}=-1 . A nontrivial band gap of 65 meV is obtained with SOC, indicating the potential for room-temperature observation and applications. The topologically protected edge states emerge at the edges of two different nanoribbons between the bulk band gap, which is consistent with the mirror Chern number. In addition, a strain-induced topological phase transition in 1S-MX2 LHS is also revealed, endowing the potential utilities in electronics and spintronics. Our predictions not only introduce new member and vitality into the studies of lateral heterostructures, but also highlight the promise of lateral heterostructure as appealing topological crystalline insulator platforms with excellent stability for future devices.

Pulsed laser deposition of II-VI and III-V semiconductor materials

Energy Technology Data Exchange (ETDEWEB)

Mele, A.; Di Palma, T.M.; Flamini, C.; Giardini Guidoni, A. [Rome, Univ. `La Sapienza` (Italy). Dep. di Chimica

1998-12-01

Pulsed laser irradiation of a solid target involves electronic excitation and heating, followed by expansion from the target of the elliptical gas cloud (plume) which can be eventually condensed on a suitable substrate. Pulsed laser ablation has been found to be a valuable technique to prepare II-VI and III-V thin films of semiconductor materials. Pulsed laser ablation deposition is discussed in the light of the results of an investigation on CdS, CdSe, CdTe and CdSe/CdTe multilayers and AIN, GaN and InN together with Al-Ga-In-N heterostructures. [Italiano] L`irradiazione di un target solido, mediante un fascio laser impulsato, genera una serie di processi che possono essere schematizzati come segue: riscaldamento ed eccitazione elettronica del target, da cui consegue l`espulsione di materiale sotto forma di una nube gassosa di forma ellissoidale (plume), che espande e puo` essere fatta depositare su un opportuno substrato. L`ablazione lasersi e` rivelata una tecnica valida per preparare film sottili di composti di elementi del II-VI e del III-V gruppo della tavola periodica. La deposizione via ablazione laser viene discussa alla luce dei risultati ottenuti nella preparazione di film di CdS, CdSe, CdTe e di film multistrato di CdSe/CdTe, di film di AIN, GaN, InN e di eterostrutture di Al-Ga-In-N.

Size Tunable Synthesis of Highly Crystalline BaTiO3 Nanoparticles using Salt-Assisted Spray Pyrolysis

International Nuclear Information System (INIS)

Itoh, Yoshifumi; Lenggoro, I. Wuled; Okuyama, Kikuo; Maedler, Lutz; Pratsinis, Sotiris E.

2003-01-01

Highly crystalline, dense BaTiO 3 nanoparticles in a size range from 30 to 360nm with a narrow size distribution (σ g = 1.2-1.4) were prepared at various synthesis temperatures using a salt-assisted spray pyrolysis (SASP) method without the need for post-annealing. The effect of synthesis temperature on particle size, crystallinity and surface morphology of the nanoparticles were characterized by X-ray diffraction and scanning/transmission electron microscopy. The nature of the crystalline structure was analyzed by Rietveld refinement and Raman spectroscopy. The particle size decreased with decreasing operation temperature. The crystal phase was transformed from tetragonal to cubic at a particles size of about 50nm at room temperature. SASP can be used to produce high weight fraction of tetragonal BaTiO 3 nanoparticles down to 64nm in a single step

Aspirin degradation in surface-charged TEMPO-oxidized mesoporous crystalline nanocellulose.

Science.gov (United States)

Carlsson, Daniel O; Hua, Kai; Forsgren, Johan; Mihranyan, Albert

2014-01-30

TEMPO-mediated surface oxidation of mesoporous highly crystalline Cladophora cellulose was used to introduce negative surface charges onto cellulose nanofibrils without significantly altering other structural characteristics. This enabled the investigation of the influence of mesoporous nanocellulose surface charges on aspirin chemical stability to be conducted. The negative surface charges (carboxylate content 0.44±0.01 mmol/g) introduced on the mesoporous crystalline nanocellulose significantly accelerated aspirin degradation, compared to the starting material which had significantly less surface charge (0.06±0.01 mmol/g). This effect followed from an increased aspirin amorphisation ability in mesopores of the oxidized nanocellulose. These results highlight the importance of surface charges in formulating nanocellulose for drug delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

Basel III and Asset Securitization

Directory of Open Access Journals (Sweden)

M. Mpundu

2013-01-01

Full Text Available Asset securitization via special purpose entities involves the process of transforming assets into securities that are issued to investors. These investors hold the rights to payments supported by the cash flows from an asset pool held by the said entity. In this paper, we discuss the mechanism by which low- and high-quality entities securitize low- and high-quality assets, respectively, into collateralized debt obligations. During the 2007–2009 financial crisis, asset securitization was seriously inhibited. In response to this, for instance, new Basel III capital and liquidity regulations were introduced. Here, we find that we can explicitly determine the transaction costs related to low-quality asset securitization. Also, in the case of dynamic and static multipliers, the effects of unexpected negative shocks such as rating downgrades on asset price and input, debt obligation price and output, and profit will be quantified. In this case, we note that Basel III has been designed to provide countercyclical capital buffers to negate procyclicality. Moreover, we will develop an illustrative example of low-quality asset securitization for subprime mortgages. Furthermore, numerical examples to illustrate the key results will be provided. In addition, connections between Basel III and asset securitization will be highlighted.

Atomistic description of large nanostructures based on III-nitride semiconductors

Energy Technology Data Exchange (ETDEWEB)

Molina-Sanchez, Alejandro; Garcia-Cristobal, Alberto; Cantarero, Andres [Instituto de Ciencia de Materiales de la Universidad de Valencia (Spain); Terentjevs, Aleksandrs; Cicero, Giancarlo [Physics and Materials Science and Chemical Engineering Departments, Politecnico di Torino (Italy)

2010-07-01

Semiconductor nanocolumns exhibiting a growth without dislocations and high crystalline quality are of great interest in nanotechnology applications. Specifically, InN-based nanocolumns are good candidates to develop multi-junction solar cells due to their small gap, 0.67 eV, and the possibility of alloying with other nitrides (as GaN and AlN) to cover the entire solar spectrum. A proper description of optical properties of the nanostructures described above can start with an atomistic treatment of the electronic structure in order to keep the essential geometry and symmetry of the objects. Unfortunately, the best description realized with ab initio electronic structure software is strongly limited by the nanocolumn diameter to a few nanometers. By using a combination of ab initio and empirical tight-binding methods, we can connect the quality of the first principles calculations (performed with the Espresso code), with the versatility of an empirical approach. Once we have an ab initio quality parameter set for the empirical tight-binding code, we can study larger nanostructures with this approach, reducing the computation time in orders of magnitude.

Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

Energy Technology Data Exchange (ETDEWEB)

Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.; Aziz, Michael J.; Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Rekemeyer, Paul H.; Gradečak, Silvija [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2015-12-14

Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

Quantitative STEM on indium containing group III-V semiconductor nanostructures

International Nuclear Information System (INIS)

Mehrtens, Thorsten

2013-01-01

In the framework of this thesis. a method for compositional analysis of semiconductor nanostructures is applied on technologically relevant group III-V alloys. It is based on a quantitative comparison between intensities of experimentally acquired High-Angle Annular Dark Field Scanning Tansmission Electron Microscopy (HAADF-STEM) images and simulated intensities from multislice calculations in the frozen lattice approach. The demonstrated method allows determination of specimen thickness and material composition on subnanometer scale. Since quantitative HAADF-STEM is still a very young technique, its applicability has only been proven for a few materials, yet. Thus, the main goal of this thesis is the simulation of suitable reference datasets for different ternary semiconducting alloys and to test their reliability by complementary analysis. A total of three different semiconducting materials are thereby analyzed (InGaN, InGaAs and InAlN) that have all in common that they contain indium. The main focus of this work lies on InGaN which is due to its bandgap particularly suitable for the fabrication of optoelectronic devices operating in the visible spectrum of the light. In the first part of the presented results, the quality of ultra-thin TEM-specimens prepared by techniques involving ion milling at high energies is optimized. This is done by an additional ion milling step where the impinging ions possess an energy of only 400 eV. It is found that the preparation induced amorphous surface layer that occurs during ion milling can be drastically reduced below 1 nm. The second part concentrates on results obtained on InGaN. Here, different simulations in the frozen lattice approach are carried out under certain conditions. These simulations either include or do not include thermal diffuse scattering and/or static atomic displacement to demonstrate their influence on the amount of intensity measured in the experiment. As the consideration of thermal diffuse scattering

High brightness InP micropillars grown on silicon with Fermi level splitting larger than 1 eV.

Science.gov (United States)

Tran, Thai-Truong D; Sun, Hao; Ng, Kar Wei; Ren, Fan; Li, Kun; Lu, Fanglu; Yablonovitch, Eli; Chang-Hasnain, Constance J

2014-06-11

The growth of III-V nanowires on silicon is a promising approach for low-cost, large-scale III-V photovoltaics. However, performances of III-V nanowire solar cells have not yet been as good as their bulk counterparts, as nanostructured light absorbers are fundamentally challenged by enhanced minority carriers surface recombination rates. The resulting nonradiative losses lead to significant reductions in the external spontaneous emission quantum yield, which, in turn, manifest as penalties in the open-circuit voltage. In this work, calibrated photoluminescence measurements are utilized to construct equivalent voltage-current characteristics relating illumination intensities to Fermi level splitting ΔF inside InP microillars. Under 1 sun, we show that splitting can exceed ΔF ∼ 0.90 eV in undoped pillars. This value can be increased to values of ΔF ∼ 0.95 eV by cleaning pillar surfaces in acidic etchants. Pillars with nanotextured surfaces can yield splitting of ΔF ∼ 0.90 eV, even though they exhibit high densities of stacking faults. Finally, by introducing n-dopants, ΔF of 1.07 eV can be achieved due to a wider bandgap energy in n-doped wurzite InP, the higher brightness of doped materials, and the extraordinarily low surface recombination velocity of InP. This is the highest reported value for InP materials grown on a silicon substrate. These results provide further evidence that InP micropillars on silicon could be a promising material for low-cost, large-scale solar cells with high efficiency.

Patterning crystalline indium tin oxide by high repetition rate femtosecond laser-induced crystallization

International Nuclear Information System (INIS)

Cheng, Chung-Wei; Lin, Cen-Ying; Shen, Wei-Chih; Lee, Yi-Ju; Chen, Jenq-Shyong

2010-01-01

A method is proposed for patterning crystalline indium tin oxide (c-ITO) patterns on amorphous ITO (a-ITO) thin films by femtosecond laser irradiation at 80 MHz repetition rate followed by chemical etching. In the proposed approach, the a-ITO film is transformed into a c-ITO film over a predetermined area via the heat accumulation energy supplied by the high repetition rate laser beam, and the unirradiated a-ITO film is then removed using an acidic etchant solution. The fabricated c-ITO patterns are observed using scanning electron microscopy and cross-sectional transmission electron microscopy. The crystalline, optical, electrical properties were measured by X-ray diffraction, spectrophotometer, and four point probe station, respectively. The experimental results show that a high repetition rate reduces thermal shock and yields a corresponding improvement in the surface properties of the c-ITO patterns.

Anisotropy-based crystalline oxide-on-semiconductor material

Science.gov (United States)

McKee, Rodney Allen; Walker, Frederick Joseph

2000-01-01

A semiconductor structure and device for use in a semiconductor application utilizes a substrate of semiconductor-based material, such as silicon, and a thin film of a crystalline oxide whose unit cells are capable of exhibiting anisotropic behavior overlying the substrate surface. Within the structure, the unit cells of the crystalline oxide are exposed to an in-plane stain which influences the geometric shape of the unit cells and thereby arranges a directional-dependent quality of the unit cells in a predisposed orientation relative to the substrate. This predisposition of the directional-dependent quality of the unit cells enables the device to take beneficial advantage of characteristics of the structure during operation. For example, in the instance in which the crystalline oxide of the structure is a perovskite, a spinel or an oxide of similarly-related cubic structure, the structure can, within an appropriate semiconductor device, exhibit ferroelectric, piezoelectric, pyroelectric, electro-optic, ferromagnetic, antiferromagnetic, magneto-optic or large dielectric properties that synergistically couple to the underlying semiconductor substrate.

Analysis of the Si(111) surface prepared in chemical vapor ambient for subsequent III-V heteroepitaxy

International Nuclear Information System (INIS)

Zhao, W.; Steidl, M.; Paszuk, A.; Brückner, S.; Dobrich, A.; Supplie, O.; Kleinschmidt, P.; Hannappel, T.

2017-01-01

Highlights: • We investigate the Si(111) surface prepared in CVD ambient at 1000 °C in 950 mbar H_2. • UHV-based XPS, LEED, STM and FTIR as well as ambient AFM are applied. • After processing the Si(111) surface is free of contamination and atomically flat. • The surface exhibits a (1 × 1) reconstruction and monohydride termination. • Wet-chemical pretreatment and homoepitaxy are required for a regular step structure. - Abstract: For well-defined heteroepitaxial growth of III-V epilayers on Si(111) substrates the atomic structure of the silicon surface is an essential element. Here, we study the preparation of the Si(111) surface in H_2-based chemical vapor ambient as well as its atomic structure after contamination-free transfer to ultrahigh vacuum (UHV). Applying complementary UHV-based techniques, we derive a complete picture of the atomic surface structure and its chemical composition. X-ray photoelectron spectroscopy measurements after high-temperature annealing confirm a Si surface free of any traces of oxygen or other impurities. The annealing in H_2 ambient leads to a monohydride surface termination, as verified by Fourier-transform infrared spectroscopy. Scanning tunneling microscopy confirms a well ordered, atomically smooth surface, which is (1 × 1) reconstructed, in agreement with low energy electron diffraction patterns. Atomic force microscopy reveals a significant influence of homoepitaxy and wet-chemical pretreatment on the surface morphology. Our findings show that wet-chemical pretreatment followed by high-temperature annealing leads to contamination-free, atomically flat Si(111) surfaces, which are ideally suited for subsequent III-V heteroepitaxy.

Studies of mono-crystalline CVD diamond pixel detectors

CERN Document Server

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

2011-01-01

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

Nano-Like Effects in Crystalline Thermoelectric Materials at High Temperatures

Science.gov (United States)

Korzhuev, M. A.; Katin, I. V.

2013-05-01

The mechanisms of improving the figure of merit Z and power parameter W of thermoelectric materials (TEMs) in the transitions λph→a and λe→a are considered (Here λph and λe are the mean free path of the phonons and electrons in the sample, and a is the inter atomic distance). It is shown that the same mechanisms are responsible for the growth of Z and W crystalline TEMs at high temperatures.

Gamma crystallins of the human eye lens.

Science.gov (United States)

Vendra, Venkata Pulla Rao; Khan, Ismail; Chandani, Sushil; Muniyandi, Anbukkarasi; Balasubramanian, Dorairajan

2016-01-01

Protein crystallins co me in three types (α, β and γ) and are found predominantly in the eye, and particularly in the lens, where they are packed into a compact, plastic, elastic, and transparent globule of proper refractive power range that aids in focusing incoming light on to the retina. Of these, the γ-crystallins are found largely in the nuclear region of the lens at very high concentrations (>400 mg/ml). The connection between their structure and inter-molecular interactions and lens transparency is an issue of particular interest. We review the origin and phylogeny of the gamma crystallins, their special structure involving the use of Greek key supersecondary structural motif, and how they aid in offering the appropriate refractive index gradient, intermolecular short range attractive interactions (aiding in packing them into a transparent ball), the role that several of the constituent amino acid residues play in this process, the thermodynamic and kinetic stability and how even single point mutations can upset this delicate balance and lead to intermolecular aggregation, forming light-scattering particles which compromise transparency. We cite several examples of this, and illustrate this by cloning, expressing, isolating and comparing the properties of the mutant protein S39C of human γS-crystallin (associated with congenital cataract-microcornea), with those of the wild type molecule. In addition, we note that human γ-crystallins are also present in other parts of the eye (e.g., retina), where their functions are yet to be understood. There are several 'crucial' residues in and around the Greek key motifs which are essential to maintain the compact architecture of the crystallin molecules. We find that a mutation that replaces even one of these residues can lead to reduction in solubility, formation of light-scattering particles and loss of transparency in the molecular assembly. Such a molecular understanding of the process helps us construct the

Pulmonary inflammation and crystalline silica in respirable coal ...

Indian Academy of Sciences (India)

Unknown

This study demonstrates dose-response relationships between respirable crystalline silica in coal mine dust and pulmonary inflammation, antioxidant production, and radiographic small opacities. [Kuempel E D, Attfield M D, Vallyathan V, Lapp N L, Hale J M, Smith R J and Castranova V 2003 Pulmonary inflammation and ...

High-quality InN films on MgO (100) substrates: The key role of 30° in-plane rotation

International Nuclear Information System (INIS)

Compeán García, V. D.; López Luna, E.; Rodríguez, A. G.; Vidal, M. A.; Orozco Hinostroza, I. E.; Escobosa Echavarría, A.

2014-01-01

High crystalline layers of InN were grown on MgO(100) substrates by gas source molecular beam epitaxy. Good quality films were obtained by means of an in-plane rotation process induced by the annealing of an InN buffer layer to minimize the misfit between InN and MgO. In situ reflection high-energy electron diffraction showed linear streaky patterns along the [011 ¯ 0] azimuth and a superimposed diffraction along the [112 ¯ 0] azimuth, which correspond to a 30° α-InN film rotation. This rotation reduces the mismatch at the MgO/InN interface from 19.5% to less than 3.5%, increasing the structural quality, which was analyzed by high-resolution X-ray diffraction and Raman spectroscopy. Only the (0002) c plane diffraction of α-InN was observed and was centered at 2θ = 31.4°. Raman spectroscopy showed two modes corresponding to the hexagonal phase: E1(LO) at 591 cm −1 and E2(high) at 488 cm −1 . Hall effect measurements showed a carrier density of 9 × 10 18  cm −3 and an electron Hall mobility of 340 cm 2 /(V s) for a film thickness of 140 nm

High bandgap III-V alloys for high efficiency optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark

2017-01-10

High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.

A highly crystalline single Au wire network as a high temperature transparent heater

Science.gov (United States)

Rao, K. D. M.; Kulkarni, Giridhar U.

2014-05-01

A transparent conductor which can generate high temperatures finds important applications in optoelectronics. In this article, a wire network made of Au on quartz is shown to serve as an effective high temperature transparent heater. The heater has been fabricated by depositing Au onto a cracked sacrificial template. The highly interconnected Au wire network thus formed exhibited a transmittance of ~87% in a wide spectral range with a sheet resistance of 5.4 Ω □-1. By passing current through the network, it could be joule heated to ~600 °C within a few seconds. The extraordinary thermal performance and stability owe much to the seamless junctions present in the wire network. Furthermore, the wire network gets self-annealed through joule heating as seen from its increased crystallinity. Interestingly, both transmittance and sheet resistance improved following annealing to 92% and 3.2 Ω □-1, respectively. A transparent conductor which can generate high temperatures finds important applications in optoelectronics. In this article, a wire network made of Au on quartz is shown to serve as an effective high temperature transparent heater. The heater has been fabricated by depositing Au onto a cracked sacrificial template. The highly interconnected Au wire network thus formed exhibited a transmittance of ~87% in a wide spectral range with a sheet resistance of 5.4 Ω □-1. By passing current through the network, it could be joule heated to ~600 °C within a few seconds. The extraordinary thermal performance and stability owe much to the seamless junctions present in the wire network. Furthermore, the wire network gets self-annealed through joule heating as seen from its increased crystallinity. Interestingly, both transmittance and sheet resistance improved following annealing to 92% and 3.2 Ω □-1, respectively. Electronic supplementary information (ESI) available: Optical micrographs, EDAX, XRD, SEM and TEM images of Au metal wires. See DOI: 10.1039/c4nr00869c

Investigation of electrically-active deep levels in single-crystalline diamond by particle-induced charge transient spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kada, W., E-mail: kada.wataru@gunma-u.ac.jp [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Kambayashi, Y.; Ando, Y. [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Onoda, S. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Umezawa, H.; Mokuno, Y. [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Shikata, S. [Kwansei Gakuin Univ., 2-1, Gakuen, Mita, Hyogo 669-1337 (Japan); Makino, T.; Koka, M. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Hanaizumi, O. [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Kamiya, T.; Ohshima, T. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan)

2016-04-01

To investigate electrically-active deep levels in high-resistivity single-crystalline diamond, particle-induced charge transient spectroscopy (QTS) techniques were performed using 5.5 MeV alpha particles and 9 MeV carbon focused microprobes. For unintentionally-doped (UID) chemical vapor deposition (CVD) diamond, deep levels with activation energies of 0.35 eV and 0.43 eV were detected which correspond to the activation energy of boron acceptors in diamond. The results suggested that alpha particle and heavy ion induced QTS techniques are the promising candidate for in-situ investigation of deep levels in high-resistivity semiconductors.

NEW THIO S2- ADDUCTS WITH ANTIMONY (III AND V HALIDE: SYNTHESIS AND INFRARED STUDY

Directory of Open Access Journals (Sweden)

HASSAN ALLOUCH

2013-12-01

Full Text Available Five new S2- adducts with SbIII and SbV halides have been synthesized and studied by infrared. Discrete structures have been suggested, the environment around the antimony being tetrahedral, trigonal bipyramidal or octahedral.

Determination of the solubility of Np(IV), Pu(III) - (VI),Am(III) - (VI), and Te(IV), (V) hydroxo compounds in 0.5 - 14 M NaOH solutions

Energy Technology Data Exchange (ETDEWEB)

Delegard, C.H.

1996-09-24

The solubilities of Am(III), Np(IV), Pu(IV), Tc(IV), Np(V), Pu(V), Am(V), and Tc(V) hydroxo compounds were studied in 0.5 to 14 M NaOH solutions at 25{+-}2 {degrees}C. The effects of fluoride, phosphate, carbonate, oxalate, and some other organic complexing agents on the solubilities of Np(IV), Pu(IV), and TC(IV) hydroxides were investigated at 1.0 and 4.0 M NAOH. Some predictions were made on the dissolved (I.V) and (V) species present in alkali solutions.

RNA aptamers targeted for human αA-crystallin do not bind αB-crystallin, and spare the α-crystallin domain.

Science.gov (United States)

Mallik, Prabhat K; Shi, Hua; Pande, Jayanti

2017-09-16

The molecular chaperones, α-crystallins, belong to the small heat shock protein (sHSP) family and prevent the aggregation and insolubilization of client proteins. Studies in vivo have shown that the chaperone activity of the α-crystallins is raised or lowered in various disease states. Therefore, the development of tools to control chaperone activity may provide avenues for therapeutic intervention, as well as enable a molecular understanding of chaperone function. The major human lens α-crystallins, αA- (HAA) and αB- (HAB), share 57% sequence identity and show similar activity towards some clients, but differing activities towards others. Notably, both crystallins contain the "α-crystallin domain" (ACD, the primary client binding site), like all other members of the sHSP family. Here we show that RNA aptamers selected for HAA, in vitro, exhibit specific affinity to HAA but do not bind HAB. Significantly, these aptamers also exclude the ACD. This study thus demonstrates that RNA aptamers against sHSPs can be designed that show high affinity and specificity - yet exclude the primary client binding region - thereby facilitating the development of RNA aptamer-based therapeutic intervention strategies. Copyright © 2017 Elsevier Inc. All rights reserved.

Quality control of a kV cone beam computed tomography imaging system

International Nuclear Information System (INIS)

Marguet, M.; Bodez, V.

2009-01-01

Purpose: This work presents the introduction of a quality assurance program for the On-Board Imager (O.B.I., Varian) kV cone beam computed tomography (kV C.B.C.T.) system, together with the results of 1 year monthly testing. Materials and methods: Firstly the geometric precision and stability of the equipment and of the associated software were evaluated using the Marker phantom. The coincidence of the accelerator isocenter and the imager isocenter was verified as well as the accuracy of the registration of kV cone beam computed tomography (kV C.B.C.T.) with reference CT images. Then, the kV C.B.C.T. image quality was evaluated using the Catphan 504 phantom and ArtiScan software (Aquilab) for both full-fan (F.F.) and half-fan (H.F.) imaging modes. Results: The kV C.B.C.T. isocenter and image registration with correction of the table position were found to be within a tolerance of 2.0 mm. Concerning the kV C.B.C.T. image quality, image noise and uniformity, the Hounsfield units (HU) stability and linearity, geometric distortion and high contrast resolution were all found to be within the manufacturer's recommendations for both F.F. and H.F. modes. However, the low contrast resolution for the HF mode did not meet the manufacturer's specifications. Conclusion: The quality assurance tests introduced have defined the initial system characteristics and their evolution during a period of 1 year, demonstrating the stability of the O.B.I.. (authors)

Factors affecting stress distribution and displacements in crystals III-V grown by Czochralski method with liquid encapsulation

International Nuclear Information System (INIS)

Schvezov, C.E.; Samarasekera, I.; Weinberg, F.

1988-01-01

A mathematical model based on the finite element method for calculating temperature and shear stress distributions in III-V crystals grown by LEC technique was developed. The calculated temperature are in good agreements with the experimental measurements. The shear stress distribution was calculated for several environmental conditions. The results showed that the magnitude and the distribution of shear stresses are highly sensitive to the crystal environment, including thickness and temperature distribution in boron oxides and the gas. The shear stress is also strongly influenced by interface curvature and cystals radius. (author) [pt

Applications of high resolution NMR to geochemistry: crystalline, glass, and molten silicates

International Nuclear Information System (INIS)

Schneider, E.

1985-11-01

The nuclear spin interactions and the associated quantum mechanical dynamics which are present in solid state NMR are introduced. A brief overview of aluminosilicate structure is presented and crystalline structure is then reviewed, with emphasis on the contributions made by 29 Si NMR spectroscopy. The local structure of glass aluminosilicates as observed by NMR, is presented with analysis of the information content of 29 Si spectra. A high-temperature (to 1300 0 C) NMR spectroscopic investigation of the local environment and dynamics of molecular motion in molten aluminosilicates is described. A comparison is made of silicate liquid, glass, and crystalline local structure. The atomic and molecular motions present in a melt are investigated through relaxation time (T 1 and T 2 ) measurements as a function of composition and temperature for 23 Na and 29 Si

Silicon, germanium, and III-V-based tunneling devices for low-power applications

Science.gov (United States)

Smith, Joshua T.

most promising low-power device candidate, owing to its potential to operate within small supply and gate voltage windows. In a critical analysis of the TFET, the advantages of 1-D systems, such as NWs, that can potentially access the so-called quantum capacitance limit (QCL) are discussed, and the remaining challenges for TFETs, such as source/channel doping abruptness, and material tradeoffs are considered. To this end, substantial performance improvements, as measured by Savg and ION, are experimentally realized in top-down fabricated Si NW-TFET arrays by systematically varying the annealing process used to enhance doping abruptness at the source/channel junction---a critical feature for maximizing tunneling efficiency. A combination of excimer laser annealing (ELA) and a low-temperature rapid thermal anneal (LT-RTA) are identified as an optimum choice, resulting in a 36% decrease in Savg as well as ˜500% improvement in ION over the conventional RTA approach. Extrapolation of these results with simulation shows that sub-60-mV/decade operation is possible on a Si-based platform for aggressively scaled, yet realistic, NW-TFET devices. Back-gated NW-FET measurements are also presented to assess the material quality of Ge/Si core/shell NW heterostructures with an n+-doped shell, and these NWs are found to be suitable building blocks for the fabrication of more efficient TFET systems, owing to the very abrupt doping profile at the shell/core (source/channel) interface and smaller bandgap/effective mass of the Ge channel. Finally, low current levels in conventional TFETs have recently led researchers to re-examine III-V heterostructures, particularly those with a broken-gap band alignment to allow a tunneling probability near unity. Along these lines, a novel tunnel-based alternative is presented---the broken-gap tunnel MOS---that enables a constant S < 60 mV/decade. The proposed device permits the use of 2-D device architectures without degradation of S given the source

CBE growth of high-quality ZnO epitaxial layers

Energy Technology Data Exchange (ETDEWEB)

El-Shaer, A.; Bakin, A.; Mofor, A.C.; Kreye, M.; Waag, A. [Institute of Semiconductor Technology, Technical University Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig (Germany); Blaesing, J.; Krost, A. [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Stoimenos, J. [Physics Department, Aristotele University, Univ. Campus, 54006 Thessaloniki (Greece); Pecz, B. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest (Hungary); Heuken, M. [Aixtron AG, Kackertstr. 15-17, 52072 Aachen (Germany)

2006-03-15

Further improvements on the recently reported novel approach to zinc oxide Chemical Beam Epitaxy (CBE) are presented. Hydrogen peroxide is employed as a very efficient novel oxidant. ZnO layers with a thickness from 100 nm to 600 nm were grown on c-sapphire using a MgO buffer. PL-mapping as well as conductivity mapping shows a good uniformity across the 2 inch ZnO-on-sapphire epiwafers. The measured surface roughness for the best layers is as low as 0.26 nm. HRXRD measurements of the obtained ZnO layers show excellent quality of the single crystalline ZnO. The FWHM of the HRXRD (0002) rocking curves measured for the 2 inch ZnO-on-sapphire wafers is as low as 27 arcsec with a very high lateral homogeneity across the whole wafer. Plane view HRTEM observations reveal the very good quality of the ZnO films. The results indicate that CBE is a suitable technique to fabricate ZnO of very high structural quality, which can eventually be used as an alternative to bulk ZnO substrates. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Synthesis of Large-Scale Single-Crystalline Monolayer WS2 Using a Semi-Sealed Method

Directory of Open Access Journals (Sweden)

Feifei Lan

2018-02-01

Full Text Available As a two-dimensional semiconductor, WS2 has attracted great attention due to its rich physical properties and potential applications. However, it is still difficult to synthesize monolayer single-crystalline WS2 at larger scale. Here, we report the growth of large-scale triangular single-crystalline WS2 with a semi-sealed installation by chemical vapor deposition (CVD. Through this method, triangular single-crystalline WS2 with an average length of more than 300 µm was obtained. The largest one was about 405 μm in length. WS2 triangles with different sizes and thicknesses were analyzed by optical microscope and atomic force microscope (AFM. Their optical properties were evaluated by Raman and photoluminescence (PL spectra. This report paves the way to fabricating large-scale single-crystalline monolayer WS2, which is useful for the growth of high-quality WS2 and its potential applications in the future.

High-LET particle dosimetry in the ASTP-Biostack III: Zea mays experiment

International Nuclear Information System (INIS)

Peterson, D.D.; Benton, E.V.; Tran, M.; Yang, T.; Freeling, M.; Craise, L.; Tobias, C.A.

1977-01-01

High-LET particle hits in embryos of Zea mays (corn) seeds, flown as part of the ASTP-Biostack III, were determined via plastic nuclear track detectors. Based on etched particle-tracks measurements, 41 embryos were hit in seed layer 1 which contained 80 seeds, and 49 hits occurred in layer 2 which contained 79 seeds. The mean LET value and range of atomic numbers of recorded hits is, respectively, 210 +- 57 keV/μm and 9 approximately less than Z approximately less than 26. Detailed analysis of one particular seed showing marked growth anomalies revealed two hits in the central region of the embryo. These two hits had LET values in the region of 100 to 150 keV/μm, and Z less than approximately 20. (author)

Amplitude dependent damping in single crystalline high purity molybdenum

International Nuclear Information System (INIS)

Zelada-Lambri, G.I; Lambri, O.A; Garcia, J.A; Lomer, J.N

2004-01-01

Amplitude dependent damping measurements were performed on high purity single crystalline molybdenum at several different constant temperatures between room temperature and 1273K. The employed samples were single crystals with the orientation, having a residual resistivity ratio of about 8000. Previously to the amplitude dependent damping tests, the samples were subjected to different thermomechanical histories. Amplitude dependent damping effects appear only during the first heating run in temperature where the samples have the thermomechanical state of the deformation process at room temperature. In the subsequent run-ups in temperature, i.e, after subsequent annealings, amplitude dependent damping effects were not detected (au)

Isolation: analysis and properties of three bradykinin-potentiating peptides (BPP-II, BPP-III, and BPP-V) from Bothrops neuwiedi venom.

Science.gov (United States)

Ferreira, L A; Galle, A; Raida, M; Schrader, M; Lebrun, I; Habermehl, G

1998-04-01

In the course of systematic investigations on low-molecular-weight compounds from the venom of Crotalidae and Viperidae, we have isolated and characterized at least three bradykinin-potentiating peptides (BPP-II, BPP-III, and BPP-V) from Bothrops neuwiedi venom by gel filtration on Sephadex G-25 M, Sephadex G-10 followed by HPLC. The peptides showed bradykinin-potentiating action on isolated guinea-pig ileum, for which the BPP-V was more active than of BPP-II, and BPP-III, rat arterial blood pressure, and a relevant angiotensin-converting enzyme (ACE) competitive inhibiting activity. The kinetic studies showed a Ki of the order of 9.7 x 10(-3) microM to BPP-II, 7 x 10(-3) microM to BPP-III, and 3.3 x 10(-3) microM to BPP-V. The amino acid sequence of the BPP-III has been determined to be pGlu-Gly-Gly-Trp-Pro-Arg-Pro-Gly-Pro-Glu-Ile-Pro-Pro, and the amino acid compositions of the BPP-II and BPP-V by amino acid analysis were 2Glu-2Gly-1Arg-4Pro-1Ile and 2Glu-2Gly-1Ser-3Pro-2Val-1Ile, with molecular weight of 1372, 1046, and 1078, respectively.

High quality β-FeSi2 thin films prepared on silicon (100) by using pulsed laser ablation of Fe target

International Nuclear Information System (INIS)

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

2012-01-01

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

Hydrogeological processes controlling water quality in the crystalline basement aquifer of the Vea Catchment in Northeast Ghana

Science.gov (United States)

Koffi, K. V.; Obuobie, E.; Banning, A.; Wohnlich, S.

2016-12-01

In the Vea catchment of Northeast Ghana, groundwater appears to be a good alternative source for domestic and agricultural water supply as surface water is largely unavailable in the prolonged dry season that characterises this semi-arid area underlain by a crystalline rock aquifer. But the usability of water depends on its quality and therefore this study was done to investigate the processes influencing groundwater hydrochemistry in the study area to inform sustainable development and use of the resource. Sixty one groundwater samples were collected from different lithologies of the crystalline aquifer, and analysed for hydrochemical and physico-chemical parameters. Results show that groundwater chemistry is governed by rock-water interaction in the area. It is mainly controlled by cation exchange and silicate weathering processes. The majority of the samples was found to cluster in the Ca-Mg-HCO3 water type, regardless of aquifer geology. From a hydrochemistry perspective, the groundwater in the area is generally suitable for irrigation and drinking purposes.

Quantum coherent transport in SnTe topological crystalline insulator thin films

Energy Technology Data Exchange (ETDEWEB)

Assaf, B. A.; Heiman, D. [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Katmis, F.; Moodera, J. S. [Francis Bitter Magnet Laboratory, MIT, Cambridge, Massachusetts 02139 (United States); Department of Physics, MIT, Cambridge, Massachusetts 02139 (United States); Wei, P. [Department of Physics, MIT, Cambridge, Massachusetts 02139 (United States); Satpati, B. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Zhang, Z. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Bennett, S. P.; Harris, V. G. [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)

2014-09-08

Topological crystalline insulators (TCI) are unique systems where a band inversion that is protected by crystalline mirror symmetry leads to a multiplicity of topological surface states. Binary SnTe is an attractive lead-free TCI compound; the present work on high-quality thin films provides a route for increasing the mobility and reducing the carrier density of SnTe without chemical doping. Results of quantum coherent magnetotransport measurements reveal a multiplicity of Dirac surface states that are unique to TCI. Modeling of the weak antilocalization shows variations in the extracted number of carrier valleys that reflect the role of coherent intervalley scattering in coupling different Dirac states on the degenerate TCI surface.

Toxicity of arsenic (III) and (V) on plant growth, element uptake, and total amylolytic activity of mesquite (Prosopis juliflora x P. velutina).

Science.gov (United States)

Mokgalaka-Matlala, Ntebogeng S; Flores-Tavizón, Edith; Castillo-Michel, Hiram; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

2008-01-01

The effects of arsenite [As(III)] and arsenate [As(V)] on the growth of roots, stems, and leaves and the uptake of arsenic (As), micro- and macronutrients, and total amylolytic activity were investigated to elucidate the phytotoxicity of As to the mesquite plant (Prosopis juliflora x P. velutina). The plant growth was evaluated by measuring the root and shoot length, and the element uptake was determined using inductively coupled plasma optical emission spectroscopy. The root and leaf elongation decreased significantly with increasing As(III) and As(V) concentrations; whereas, stem elongation remained unchanged. The As uptake increased with increasing As(III) or As(V) concentrations in the medium. Plants treated with 50 mg/L As(III) accumulated up to 920 mg/kg dry weight (d wt) in roots and 522 mg/kg d wt in leaves, while plants exposed to 50 mg/L As(V) accumulated 1980 and 210 mg/kg d wt in roots and leaves, respectively. Increasing the As(V) concentration up to 20 mg/L resulted in a decrease in the total amylolytic activity. On the contrary, total amylolytic activity in As(III)-treated plants increased with increasing As concentration up to 20 mg/L. The macro- and micronutrient concentrations changed in As-treated plants. In shoots, Mo and K were reduced but Ca was increased, while in roots Fe and Ca were increased but K was reduced. These changes reduced the size of the plants, mainly in the As(III)-treated plants; however, there were no visible sign of As toxicity.

High Temperature NMR Studies of the Glass-Crystal Transition in the Cs2S2O7-V2O5 System

DEFF Research Database (Denmark)

Lapina, Olga B.; Terskikh, Viktor V.; Shubin, Aleksander A.

1997-01-01

133Cs and 51V NMR spectra have been recorded of Cs2S2O7 and the catalytically important Cs2S2O7-V2O5 mixtures in the temperature range 20 - 550 C. A high mobility of Cs+ in the solid Cs2S2O7 was observed. The transformation from glassy state to crystalline state was investigated for the compositi...

High Efficiency, Low Cost Solar Cells Manufactured Using 'Silicon Ink' on Thin Crystalline Silicon Wafers

Energy Technology Data Exchange (ETDEWEB)

Antoniadis, H.

2011-03-01

Reported are the development and demonstration of a 17% efficient 25mm x 25mm crystalline Silicon solar cell and a 16% efficient 125mm x 125mm crystalline Silicon solar cell, both produced by Ink-jet printing Silicon Ink on a thin crystalline Silicon wafer. To achieve these objectives, processing approaches were developed to print the Silicon Ink in a predetermined pattern to form a high efficiency selective emitter, remove the solvents in the Silicon Ink and fuse the deposited particle Silicon films. Additionally, standard solar cell manufacturing equipment with slightly modified processes were used to complete the fabrication of the Silicon Ink high efficiency solar cells. Also reported are the development and demonstration of a 18.5% efficient 125mm x 125mm monocrystalline Silicon cell, and a 17% efficient 125mm x 125mm multicrystalline Silicon cell, by utilizing high throughput Ink-jet and screen printing technologies. To achieve these objectives, Innovalight developed new high throughput processing tools to print and fuse both p and n type particle Silicon Inks in a predetermined pat-tern applied either on the front or the back of the cell. Additionally, a customized Ink-jet and screen printing systems, coupled with customized substrate handling solution, customized printing algorithms, and a customized ink drying process, in combination with a purchased turn-key line, were used to complete the high efficiency solar cells. This development work delivered a process capable of high volume producing 18.5% efficient crystalline Silicon solar cells and enabled the Innovalight to commercialize its technology by the summer of 2010.

Results of Operative and Nonoperative Treatment of Rockwood Types III and V Acromioclavicular Joint Dislocation

Science.gov (United States)

Joukainen, Antti; Kröger, Heikki; Niemitukia, Lea; Mäkelä, E. Antero; Väätäinen, Urho

2014-01-01

Background: The optimal treatment of acute, complete dislocation of the acromioclavicular joint (ACJ) is still unresolved. Purpose: To determine the difference between operative and nonoperative treatment in acute Rockwood types III and V ACJ dislocation. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: In the operative treatment group, the ACJ was reduced and fixed with 2 transarticular Kirschner wires and ACJ ligament suturing. The Kirschner wires were extracted after 6 weeks. Nonoperatively treated patients received a reduction splint for 4 weeks. At the 18- to 20-year follow-up, the Constant, University of California at Los Angeles Shoulder Rating Scale (UCLA), Larsen, and Simple Shoulder Test (SST) scores were obtained, and clinical and radiographic examinations of both shoulders were performed. Results: Twenty-five of 35 potential patients were examined at the 18- to 20-year follow-up. There were 11 patients with Rockwood type III and 14 with type V dislocations. Delayed surgical treatment for ACJ was used in 2 patients during follow-up: 1 in the operatively treated group and 1 in the nonoperatively treated group. Clinically, ACJs were statistically significantly less prominent or unstable in the operative group than in the nonoperative group (normal/prominent/unstable: 9/4/3 and 0/6/3, respectively; P = .02) and in the operative type III (P = .03) but not type V dislocation groups. In operatively and nonoperatively treated patients, the mean Constant scores were 83 and 85, UCLA scores 25 and 27, Larsen scores 11 and 11, and SST scores 11 and 12 at follow-up, respectively. There were no statistically significant differences in type III and type V dislocations. In the radiographic analysis, the ACJ was wider in the nonoperative than the operative group (8.3 vs 3.4 mm; P = .004), and in the type V dislocations (nonoperative vs operative: 8.5 vs 2.4 mm; P = .007). There was no statistically significant difference between study groups in

Area Recommendation Report for the Crystalline Repository Project: Volume 1, Draft

International Nuclear Information System (INIS)

1986-01-01

This Draft Area Recommendation Report for the Crystalline Repository Project identifies portions of crystalline rock bodies as proposed potentially acceptable sites for consideration in the second high-level radioactive waste repository program. The US Department of Energy evaluated available geologic and environmental data for 235 crystalline rock bodies in the North Central, Northeastern, and Southeastern regions to identify preliminary candidate areas. Further evaluation of these preliminary candidate areas resulted in the selection of 12 as proposed potentially acceptable sites. The 12 proposed potentially acceptable sites are located in the States of Georgia (1), Maine (2), Minnesota (3), New Hampshire (1), North Carolina (2), Virginia (2), and Wisconsin (1). The data, analyses, and rationale with which the 12 proposed potentially acceptable sites were selected are presented in this draft report. The analyses presented demonstrate that the evidence available for each proposed potentially acceptable site supports (1) a finding that the site is not disqualified in accordance with the application requirements of Appendix III of the siting guidelines and (2) a decision to proceed with the continued investigation of the site on the basis of the favorable and potentially adverse conditions identified to date. Once this report is finalized, potentially acceptable sites in crystalline rock will be formally identified by the Secretary of Energy, in accordance with the DOE siting guidelines. These potentially acceptable sites will be investigated and evaluated in more detail during the area phase of the siting process. An additional eight areas, which meet the requirements for identification as potentially acceptable sites, will retain their designation as candidate areas

High quality atomically thin PtSe2 films grown by molecular beam epitaxy

Science.gov (United States)

Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

2017-12-01

Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations.

Science.gov (United States)

Roberts, Linda C; Hug, Stephan J; Ruettimann, Thomas; Billah, Morsaline; Khan, Abdul Wahab; Rahman, Mohammad Tariqur

2004-01-01

Arsenic removal by passive treatment, in which naturally present Fe(II) is oxidized by aeration and the forming iron(III) (hydr)oxides precipitate with adsorbed arsenic, is the simplest conceivable water treatment option. However, competing anions and low iron concentrations often require additional iron. Application of Fe(II) instead of the usually applied Fe(III) is shown to be advantageous, as oxidation of Fe(II) by dissolved oxygen causes partial oxidation of As(III) and iron(III) (hydr)oxides formed from Fe(II) have higher sorption capacities. In simulated groundwater (8.2 mM HCO3(-), 2.5 mM Ca2+, 1.6 mM Mg2+, 30 mg/L Si, 3 mg/L P, 500 ppb As(III), or As(V), pH 7.0 +/- 0.1), addition of Fe(II) clearly leads to better As removal than Fe(III). Multiple additions of Fe(II) further improved the removal of As(II). A competitive coprecipitation model that considers As(III) oxidation explains the observed results and allows the estimation of arsenic removal under different conditions. Lowering 500 microg/L As(III) to below 50 microg/L As(tot) in filtered water required > 80 mg/L Fe(III), 50-55 mg/L Fe(II) in one single addition, and 20-25 mg/L in multiple additions. With As(V), 10-12 mg/L Fe(II) and 15-18 mg/L Fe(III) was required. In the absence of Si and P, removal efficiencies for Fe(II) and Fe(III) were similar: 30-40 mg/L was required for As(II), and 2.0-2.5 mg/L was required for As(V). In a field study with 22 tubewells in Bangladesh, passive treatment efficiently removed phosphate, but iron contents were generally too low for efficient arsenic removal.

Synthesis and characterization of single-crystalline zinc tin oxide nanowires

Science.gov (United States)

Shi, Jen-Bin; Wu, Po-Feng; Lin, Hsien-Sheng; Lin, Ya-Ting; Lee, Hsuan-Wei; Kao, Chia-Tze; Liao, Wei-Hsiang; Young, San-Lin

2014-05-01

Crystalline zinc tin oxide (ZTO; zinc oxide with heavy tin doping of 33 at.%) nanowires were first synthesized using the electrodeposition and heat treatment method based on an anodic aluminum oxide (AAO) membrane, which has an average diameter of about 60 nm. According to the field emission scanning electron microscopy (FE-SEM) results, the synthesized ZTO nanowires are highly ordered and have high wire packing densities. The length of ZTO nanowires is about 4 μm, and the aspect ratio is around 67. ZTO nanowires with a Zn/(Zn + Sn) atomic ratio of 0.67 (approximately 2/3) were observed from an energy dispersive spectrometer (EDS). X-ray diffraction (XRD) and corresponding selected area electron diffraction (SAED) patterns demonstrated that the ZTO nanowire is hexagonal single-crystalline. The study of ultraviolet/visible/near-infrared (UV/Vis/NIR) absorption showed that the ZTO nanowire is a wide-band semiconductor with a band gap energy of 3.7 eV.

Factors to Enable Crystallization of Environmentally Stable Bioscorodite from Dilute As(III-Contaminated Waters

Directory of Open Access Journals (Sweden)

Masahito Tanaka

2018-01-01

Full Text Available Applicability of the bioscorodite method (use of the thermo-acidophilic Fe(II-oxidizing archaeon Acidianus brierleyi for arsenic (As oxidation and immobilization at 70 °C was tested for synthetic copper refinery wastewaters of a wide range of dilute initial As(III concentrations ([As(III]ini = 3.3–20 mM with varying initial [Fe(II]/[As(III] molar ratios ([Fe(II]ini/[As(III]ini = 0.8–6.0. Crystallization of scorodite (FeAsO4·2H2O tends to become increasingly challenging at more dilute As(III solutions. Optimization of conditions such as initial pH, seed feeding and initial [Fe(II]/[As(III] molar ratio was found critical in improving final As removal and product stability: Whilst setting the initial pH at 1.2 resulted in an immediate single-stage precipitation of crystalline bioscorodite, the initial pH 1.5 led to a two-stage As precipitation (generation of brown amorphous precursors followed by whitish crystalline bioscorodite particles with a greater final As removal. The formation process of bioscorodite precipitates differed significantly depending on the type of seed crystals fed (bio- versus chemical- scorodite seeds. Feeding the former was found effective not only in accelerating the reaction, but also in forming more recalcitrant bioscorodite products (0.59 mg/L; Toxicity Characteristic Leaching Procedure (TCLP test. Under such favorable conditions, 94–99% of As was successfully removed as crystalline bioscorodite at all dilute As(III concentrations tested by setting [Fe(II]ini/[As(III]ini at 1.4–2.0. Providing an excess Fe(II (closer to [Fe(II]ini/[As(III]ini = 2.0 was found beneficial to improve the final As removal (up to 98–99% especially from more dilute As(III solutions.

Experimental synthesis of crystalline matrices based on Ce, Ba, Sr zirconates for immobilization of high-level radioactive actinides

International Nuclear Information System (INIS)

Anderson, E.B.; Burakov, B.E.; Vasiliev, V.G.; Starchenko, V.A.

1993-01-01

In geological disposal of high-level radioactive waste the main storage barriers, in the first place the matrix containing radionuclides, must remain undestructible over a long period of time. Very high requirements are imposed for the matrices from the viewpoint of their chemical stability and mechanical strength. Zirconates may be classified among compounds potentially suitable for the creation of crystalline matrices incorporating radionuclides in their structure. The paper considers results of laboratory experiments on the synthesis of crystalline matrices based on various zirconates by the methods of gas-static and axial pressing. Problems are discussed concerning the crystalline matrix industrial synthesis technology developed at the Radium Institute. One of the most promising directions in solving the problem of high-level waste (HLW) removal from the sphere of human activity is disposal in deep geological formations. The realization of this direction envisages creation of multibarrier compositions. Special attention is paid to the technology for the synthesis of the first, the most crucial, engineering barrier: the matrix into which radionuclides are incorporated. It is assumed that crystalline compounds best satisfy all the requirements as the most thermodynamically stable

Channeled-ion implantation of group-III and group-V ions into silicon

International Nuclear Information System (INIS)

Furuya, T.; Nishi, H.; Inada, T.; Sakurai, T.

1978-01-01

Implantation of group-III and group-V ions along [111] and [110] axes of silicon have been performed using a backscattering technique, and the depth profiles of implanted ions have been measured by the C-V method. The range of channeled Ga ions is the largest among the present data, and a p-type layer of about 6 μm is obtained by implantation at only 150 keV. The carrier profiles of channeled Al and Ga ions with deep ranges do not show any distinguishable channeled peak contrasting with the B, P, and As channeling which gives a well-defined peak. The electronic stopping cross section (S/sub e/) of channeled P ions agree well with the results of Eisen and Reddi, but in B channeling, the discrepancies of 10--20% are observed among S/sub e/ values obtained experimentally by three different groups

Value of TIRADS, BSRTC and FNA-BRAF V600E mutation analysis in differentiating high-risk thyroid nodules.

Science.gov (United States)

Zhang, Yu-zhi; Xu, Ting; Cui, Dai; Li, Xiao; Yao, Qing; Gong, Hai-yan; Liu, Xiao-yun; Chen, Huan-huan; Jiang, Lin; Ye, Xin-hua; Zhang, Zhi-hong; Shen, Mei-ping; Duan, Yu; Yang, Tao; Wu, Xiao-hong

2015-11-24

The thyroid imaging reporting and data system (TIRADS) and Bethesda system for reporting thyroid cytopathology (BSRTC) have been used for interpretation of ultrasound and fine-needle aspiration cytology (FNAC) results of thyroid nodules. BRAF(V600E) mutation analysis is a molecular tool in diagnosing thyroid carcinoma. Our objective was to compare the diagnostic value of these methods in differentiating high-risk thyroid nodules. Total 220 patients with high-risk thyroid nodules were recruited in this prospective study. They all underwent ultrasound, FNAC and BRAF(V600E) mutation analysis. The sensitivity and specificity of TIRADS were 73.1% and 88.4%. BSRTC had higher specificity (97.7%) and similar sensitivity (77.6%) compared with TIRADS. The sensitivity and specificity of BRAF(V600E) mutation (85.1%, 100%) were the highest. The combination of BSRTC and BRAF(V600E) mutation analysis significantly increased the efficiency, with 97.8% sensitivity, 97.7% specificity. In patients with BSRTC I-III, the mutation rate of BRAF(V600E) was 64.5% in nodules with TIRADS 4B compared with 8.4% in nodules with TIRADS 3 or 4A (P value in differentiating high-risk thyroid nodules. The TIRADS is useful in selecting high-risk patients for FNAB and patients with BSRTC I-III for BRAF(V600E) mutation analysis.

Preparation of high magneto-optical performance and crystalline quality Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} films on CLNGG substrate crystal

Energy Technology Data Exchange (ETDEWEB)

Fu, Qiu-ping; Zheng, Ze-yuan; Lin, Nan-xi; Liu, Xiao-feng; Hong, Can-huang; Hu, Xiao-lin, E-mail: linamethyst@fzu.edu.cn; Zhuang, Nai-feng; Chen, Jian-zhong, E-mail: j.z.chen@fzu.edu.cn

2016-11-01

Thin films of Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} (Ce,Ga:GIG) were prepared on Gd{sub 3}Ga{sub 5}O{sub 12} (GGG) and Ca{sub 2.90}Li{sub 0.30}Nb{sub 1.93}Ga{sub 2.76}O{sub 12} (CLNGG) substrates by using radio frequency magnetron sputtering technique. The phase, grain orientation, surface morphology, transmittance, magnetism and magnetic circular dichroism (MCD) properties of films were analyzed. And the effects of lattice mismatch and non-magnetic Ga{sup 3+}-doping were discussed. The results show that the films with higher crystallized quality and lower stress can be obtained by growing on CLNGG than on GGG. Moreover, the coercive force, magnetization, magneto-optical effect intensity and orientation of film can be effectively regulated by adjusting Ga{sup 3+}-doped concentration. - Highlights: • With excellent magneto-optical performance, Ce,Ga:GIG film has a good application prospect. • Ce,Ga:GIG film with high quality were prepared on CLNGG by RF magnetron sputtering. • Crystalline quality and morphology of films are intently related to the substrate. • Ga{sup 3+} doping obviously affect on magnetism and magneto-optical property of Ce:GIG film.

Neutron capture therapy of epidermal growth factor receptor (EGFR)vIII positive gliomas using boronated monoclonal antibody L8A4

International Nuclear Information System (INIS)

Yang, Weilian; Barth, Rolf F.; Wu, Gong

2006-01-01

The purpose of the present study was to evaluate the EGFRvIII specific monoclonal antibody, L8A4 as a boron delivery agent for NCT of the receptor (+) rat glioma, F98 npEGFRvIII . A heavily boronated polyamidoamine (PAMAM) dendrimer (BD) was linked to L8A4 by means of heterobifunctional reagents. Wild type (F98 WT ) receptor(-) or EGFRvIII human gene transfected receptor(+) F98 npEGFRvIII glioma cells were implanted into the brains of Fischer rats. Biodistribution studies were initiated 14 d later. Animals received 125 I-labeled BD-L8A4 by either convection enhanced delivery (CED) or intratumoral(i.t.) injection and were euthanized 6, 12, 24 or 48 h later. At 6 h following CED, equivalent amounts of the bioconjugate were detected in receptor(+) and (-) tumors, but by 24 h the amounts retained by receptor(+) gliomas were 60.1% following CED and 43.7% following i.t. injection, compared to 14.6% ID/g by receptor(-) tumors. Tumor boron concentrations were 32.7 and 44.5 μg/g, respectively, for BD-L8A4 alone or in combination with i.v. BPA. BNCT was carried out at the MITR-II Reactor 24 h after CED of BD-L8A4 (∼40 μg 10 B/∼750 μg protein) and 2.5 h after i.v. injection of BPA (500 mg/kg). Rats that received BD-L8A4 alone or in combination with BPA had mean survival times of 70.4 and 85d, respectively, with 20% and 10% long term survivors, respectively, compared to 40.1 d for i.v. BPA and 30.3 and 26.3 d for irradiated and untreated controls, respectively. These data convincingly demonstrate the therapeutic efficacy of molecular targeting of EGFRvIII and should provide a platform for the future development of combinations of high and low molecular weight delivery agents for BNCT of brain tumors. (author)

The Effective Dynamic Ranges for Glaucomatous Visual Field Progression With Standard Automated Perimetry and Stimulus Sizes III and V.

Science.gov (United States)

Wall, Michael; Zamba, Gideon K D; Artes, Paul H

2018-01-01

It has been shown that threshold estimates below approximately 20 dB have little effect on the ability to detect visual field progression in glaucoma. We aimed to compare stimulus size V to stimulus size III, in areas of visual damage, to confirm these findings by using (1) a different dataset, (2) different techniques of progression analysis, and (3) an analysis to evaluate the effect of censoring on mean deviation (MD). In the Iowa Variability in Perimetry Study, 120 glaucoma subjects were tested every 6 months for 4 years with size III SITA Standard and size V Full Threshold. Progression was determined with three complementary techniques: pointwise linear regression (PLR), permutation of PLR, and linear regression of the MD index. All analyses were repeated on "censored'' datasets in which threshold estimates below a given criterion value were set to equal the criterion value. Our analyses confirmed previous observations that threshold estimates below 20 dB contribute much less to visual field progression than estimates above this range. These findings were broadly similar with stimulus sizes III and V. Censoring of threshold values < 20 dB has relatively little impact on the rates of visual field progression in patients with mild to moderate glaucoma. Size V, which has lower retest variability, performs at least as well as size III for longitudinal glaucoma progression analysis and appears to have a larger useful dynamic range owing to the upper sensitivity limit being higher.

Population III Stars and Remnants in High-redshift Galaxies

Science.gov (United States)

Xu, Hao; Wise, John H.; Norman, Michael L.

2013-08-01

Recent simulations of Population III star formation have suggested that some fraction form in binary systems, in addition to having a characteristic mass of tens of solar masses. The deaths of metal-free stars result in the initial chemical enrichment of the universe and the production of the first stellar-mass black holes. Here we present a cosmological adaptive mesh refinement simulation of an overdense region that forms a few 109 M ⊙ dark matter halos and over 13,000 Population III stars by redshift 15. We find that most halos do not form Population III stars until they reach M vir ~ 107 M ⊙ because this biased region is quickly enriched from both Population III and galaxies, which also produce high levels of ultraviolet radiation that suppress H2 formation. Nevertheless, Population III stars continue to form, albeit in more massive halos, at a rate of ~10-4 M ⊙ yr-1 Mpc-3 at redshift 15. The most massive starless halo has a mass of 7 × 107 M ⊙, which could host massive black hole formation through the direct gaseous collapse scenario. We show that the multiplicity of the Population III remnants grows with halo mass above 108 M ⊙, culminating in 50 remnants located in 109 M ⊙ halos on average. This has implications that high-mass X-ray binaries and intermediate-mass black holes that originate from metal-free stars may be abundant in high-redshift galaxies.

Applications of high resolution NMR to geochemistry: crystalline, glass, and molten silicates

Energy Technology Data Exchange (ETDEWEB)

Schneider, E.

1985-11-01

The nuclear spin interactions and the associated quantum mechanical dynamics which are present in solid state NMR are introduced. A brief overview of aluminosilicate structure is presented and crystalline structure is then reviewed, with emphasis on the contributions made by /sup 29/Si NMR spectroscopy. The local structure of glass aluminosilicates as observed by NMR, is presented with analysis of the information content of /sup 29/Si spectra. A high-temperature (to 1300/sup 0/C) NMR spectroscopic investigation of the local environment and dynamics of molecular motion in molten aluminosilicates is described. A comparison is made of silicate liquid, glass, and crystalline local structure. The atomic and molecular motions present in a melt are investigated through relaxation time (T/sub 1/ and T/sub 2/) measurements as a function of composition and temperature for /sup 23/Na and /sup 29/Si.

A comparative study of the metastable equilibrium solubility behavior of high-crystallinity and low-crystallinity carbonated apatites using pH and solution strontium as independent variables.

Science.gov (United States)

Heslop, D D; Bi, Y; Baig, A A; Otsuka, M; Higuchi, W I

2005-09-01

Using solution strontium and pH as independent variables, the metastable equilibrium solubility (MES) behavior of two carbonated apatite (CAP) samples has been examined, a high-crystallinity CAP (properties expected to be similar to dental enamel) and a low-crystallinity CAP (properties expected to be similar to bone mineral). CAP samples were prepared by precipitation/digestion: (CAP A: high-crystallinity, 1.3 wt% CO3, synthesized at 85 degrees C; CAP B: low-crystallinity, 6.4 wt% CO3, synthesized at 50 degrees C). Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. To assess the influence of strontium, MES profiles were determined in a similar fashion with 20, 40, 60, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. To determine the correct function governing CAP dissolution, ion activity products (IAPs) were calculated from the compositions of buffer solutions based on the hydroxyapatite template (Ca(10-n)Sr(n)(PO4)6(OH)2 (n = 0-10)) and the calcium/hydroxide deficient hydroxyapatite template (Ca(9-n)Sr(n)(HPO4)(PO4)5OH (n = 0-9)). (a) for CAP A, at high solution strontium/calcium ratios, the MES profiles were essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca6Sr4(PO4)6(OH)2 and for CAP B by a stoichiometry of Ca7Sr2(HPO4)(PO4)5OH; (b) for CAP A, at low strontium/calcium ratios, the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite and for CAP B, that of calcium/hydroxide deficient hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.

Effect of growth interruption on the crystalline quality and electrical properties of Ga-doped ZnO thin film deposited on quartz substrate by magnetron sputtering

International Nuclear Information System (INIS)

Lee, Geun-Hyoung

2013-01-01

Ga-doped ZnO(GZO) thin films were deposited on the quartz substrate by magnetron sputtering system with growth interruption technique. As the number of interruptions and interruption time increased, the carrier concentration and Hall mobility in GZO films significantly increased. As a result, the resistivity of GZO films decreased. The optical transmittance of GZO films also increased with the number of interruption and interruption time. The transmittance showed over 90% in visual region. Atomic force microscopy measurement showed that the film surface became smoother with an increase of the number of interruption. In addition, the crystalline quality and electrical properties of GZO films were more improved when the growth interruption was employed with a temperature gradient. - Highlights: • Ga-doped ZnO thin films were deposited with growth interruption technique. • The crystallinity of the films was improved with the number of interruptions. • The crystallinity of the films was improved as the interruption time increased. • The growth interruption with a temperature gradient more improved the film quality

Analysis of the Si(111) surface prepared in chemical vapor ambient for subsequent III-V heteroepitaxy

Energy Technology Data Exchange (ETDEWEB)

Zhao, W.; Steidl, M.; Paszuk, A. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Brückner, S. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institut für Solare Brennstoffe, 14109 Berlin (Germany); Dobrich, A. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Supplie, O. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institut für Solare Brennstoffe, 14109 Berlin (Germany); Kleinschmidt, P. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Hannappel, T., E-mail: thomas.hannappel@tu-ilmenau.de [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institut für Solare Brennstoffe, 14109 Berlin (Germany)

2017-01-15

Highlights: • We investigate the Si(111) surface prepared in CVD ambient at 1000 °C in 950 mbar H{sub 2}. • UHV-based XPS, LEED, STM and FTIR as well as ambient AFM are applied. • After processing the Si(111) surface is free of contamination and atomically flat. • The surface exhibits a (1 × 1) reconstruction and monohydride termination. • Wet-chemical pretreatment and homoepitaxy are required for a regular step structure. - Abstract: For well-defined heteroepitaxial growth of III-V epilayers on Si(111) substrates the atomic structure of the silicon surface is an essential element. Here, we study the preparation of the Si(111) surface in H{sub 2}-based chemical vapor ambient as well as its atomic structure after contamination-free transfer to ultrahigh vacuum (UHV). Applying complementary UHV-based techniques, we derive a complete picture of the atomic surface structure and its chemical composition. X-ray photoelectron spectroscopy measurements after high-temperature annealing confirm a Si surface free of any traces of oxygen or other impurities. The annealing in H{sub 2} ambient leads to a monohydride surface termination, as verified by Fourier-transform infrared spectroscopy. Scanning tunneling microscopy confirms a well ordered, atomically smooth surface, which is (1 × 1) reconstructed, in agreement with low energy electron diffraction patterns. Atomic force microscopy reveals a significant influence of homoepitaxy and wet-chemical pretreatment on the surface morphology. Our findings show that wet-chemical pretreatment followed by high-temperature annealing leads to contamination-free, atomically flat Si(111) surfaces, which are ideally suited for subsequent III-V heteroepitaxy.

Teachers' Guide to Music Appreciation III A and III B in the Senior High School.

Science.gov (United States)

Scott, J. Mark; Dawkins, Barbara R.

This guide to music appreciation courses was developed for use in senior high schools in Duval County, Jacksonville, Florida. Music Appreciation III A examines the development of music, from the Gothic period through the Classical period. Music Appreciation III B examines the development of music from the Romantic period through the 1970s.…

Improvements in numerical modelling of highly injected crystalline silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Altermatt, P.P. [University of New South Wales, Centre for Photovoltaic Engineering, 2052 Sydney (Australia); Sinton, R.A. [Sinton Consulting, 1132 Green Circle, 80303 Boulder, CO (United States); Heiser, G. [University of NSW, School of Computer Science and Engineering, 2052 Sydney (Australia)

2001-01-01

We numerically model crystalline silicon concentrator cells with the inclusion of band gap narrowing (BGN) caused by injected free carriers. In previous studies, the revised room-temperature value of the intrinsic carrier density, n{sub i}=1.00x10{sup 10}cm{sup -3}, was inconsistent with the other material parameters of highly injected silicon. In this paper, we show that high-injection experiments can be described consistently with the revised value of n{sub i} if free-carrier induced BGN is included, and that such BGN is an important effect in silicon concentrator cells. The new model presented here significantly improves the ability to model highly injected silicon cells with a high level of precision.

Wide bandgap collector III-V double heterojunction bipolar transistors

International Nuclear Information System (INIS)

Flitcroft, R.M.

2000-10-01

This thesis is devoted to the study and development of Heterojunction Bipolar Transistors (HBTs) designed for high voltage operation. The work concentrates on the use of wide bandgap III-V semiconductor materials as the collector material and their associated properties influencing breakdown, such as impact ionisation coefficients. The work deals with issues related to incorporating a wide bandgap collector into double heterojunction structures such as conduction band discontinuities at the base-collector junction and results are presented which detail, a number of methods designed to eliminate the effects of such discontinuities. In particular the use of AlGaAs as the base material has been successful in eliminating the conduction band spike at this interface. A method of electrically injecting electrons into the collector has been employed to investigate impact ionisation in GaAs, GaInP and AlInP which has used the intrinsic gain of the devices to extract impact ionisation coefficients over a range of electric fields beyond the scope of conventional optical injection techniques. This data has enabled the study of ''dead space'' effects in HBT collectors and have been used to develop an analytical model of impact ionisation which has been incorporated into an existing Ebers-Moll HBT simulator. This simulator has been shown to accurately reproduce current-voltage characteristics in both the devices used in this work and for external clients. (author)

Alpha B- and βA3-crystallins containing d-aspartic acids exist in a monomeric state.

Science.gov (United States)

Sakaue, Hiroaki; Takata, Takumi; Fujii, Norihiko; Sasaki, Hiroshi; Fujii, Noriko

2015-01-01

Crystallin stability and subunit-subunit interaction are essential for eye lens transparency. There are three types of crystallins in lens, designated as α-, β-, and γ-crystallins. Alpha-crystallin is a hetero-polymer of about 800kDa, consisting of 35-40 subunits of two different αA- and αB-subunits, each of 20kDa. The β/γ-crystallin superfamily comprises oligomeric β-crystallin (2-6 subunits) and monomeric γ-crystallin. Since lens proteins have very long half-lives, they undergo numerous post-translational modifications including racemization, isomerization, deamidation, oxidation, glycation, and truncation, which may decrease crystallin solubility and ultimately cause cataract formation. Racemization and isomerization of aspartyl (Asp) residues have been detected only in polymeric α- and oligomeric β-crystallin, while the situation in monomeric γ-crystallin has not been studied. Here, we investigated the racemization and isomerization of Asp in the γ-crystallin fraction of elderly donors. The results show that Asp residues of γS-, γD- and γC-crystallins were not racemized and isomerized. However, strikingly, we found that a portion of αB-crystallin and βA3-crystallin moved to the lower molecular weight fraction which is the same size of γ-crystallin. In those fractions, Asp-96 of αB-crystallin and Asp-37 of βA3-crystallin were highly inverted, which do not occur in the native lens higher molecular weight fraction. Our results indicate the possibility that the inversion of Asp residues may induce dissociation of αB- and βA3-crystallins from the polymeric and oligomeric states. This is the first report that stereoinversion of amino acids disturbs lens protein assembly in aged human lens. Copyright © 2014 Elsevier B.V. All rights reserved.

Cloud point extraction of iron(III) and vanadium(V) using 8-quinolinol derivatives and Triton X-100 and determination of 10(-7)moldm(-3) level iron(III) in riverine water reference by a graphite furnace atomic absorption spectroscopy.

Science.gov (United States)

Ohashi, Akira; Ito, Hiromi; Kanai, Chikako; Imura, Hisanori; Ohashi, Kousaburo

2005-01-30

The cloud point extraction behavior of iron(III) and vanadium(V) using 8-quinolinol derivatives (HA) such as 8-quinolinol (HQ), 2-methyl-8-quinolinol (HMQ), 5-butyloxymethyl-8-quinolinol (HO(4)Q), 5-hexyloxymethyl-8-quinolinol (HO(6)Q), and 2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q) and Triton X-100 solution was investigated. Iron(III) was extracted with HA and 4% (v/v) Triton X-100 in the pH range of 1.70-5.44. Above pH 4.0, more than 95% of iron(III) was extracted with HQ, HMQ, and HMO(8)Q. Vanadium(V) was also extracted with HA and 4% (v/v) Triton X-100 in the pH range of 2.07-5.00, and the extractability increased in the following order of HMQ HQ cloud point extraction was applied to the determination of iron(III) in the riverine water reference by a graphite furnace atomic absorption spectroscopy. When 1.25 x 10(-3)M HMQ and 1% (v/v) Triton X-100 were used, the found values showed a good agreement with the certified ones within the 2% of the R.S.D. Moreover, the effect of an alkyl group on the solubility of 5-alkyloxymethyl-8-quinolinol and 2-methyl-5-alkyloxymethyl-8-quinolinol in 4% (v/v) Triton X-100 at 25 degrees C was also investigated.

Crystalline and Crystalline International Disposal Activities

Energy Technology Data Exchange (ETDEWEB)

Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-03-06

This report presents the results of work conducted between September 2015 and July 2016 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program. Los Alamos focused on two main activities during this period: Discrete fracture network (DFN) modeling to describe flow and radionuclide transport in complex fracture networks that are typical of crystalline rock environments, and a comprehensive interpretation of three different colloid-facilitated radionuclide transport experiments conducted in a fractured granodiorite at the Grimsel Test Site in Switzerland between 2002 and 2013. Chapter 1 presents the results of the DFN work and is divided into three main sections: (1) we show results of our recent study on the correlation between fracture size and fracture transmissivity (2) we present an analysis and visualization prototype using the concept of a flow topology graph for characterization of discrete fracture networks, and (3) we describe the Crystalline International work in support of the Swedish Task Force. Chapter 2 presents interpretation of the colloidfacilitated radionuclide transport experiments in the crystalline rock at the Grimsel Test Site.

Use of radial self-field geometry for intense pulsed ion beam generation above 6 MeV on Hermes III.

Energy Technology Data Exchange (ETDEWEB)

Renk, Timothy Jerome [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Harper-Slaboszewicz, Victor Jozef [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ginn, William Craig [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mikkelson, Kenneth A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schall, Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cooper, Gary Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2012-12-01

We investigate the generation and propagation of intense pulsed ion beams at the 6 MeV level and above using the Hermes III facility at Sandia National Laboratories. While high-power ion beams have previously been produced using Hermes III, we have conducted systematic studies of several ion diode geometries for the purpose of maximizing focused ion energy for a number of applications. A self-field axial-gap diode of the pinch reflex type and operated in positive polarity yielded beam power below predicted levels. This is ascribed both to power flow losses of unknown origin upstream of the diode load in Hermes positive polarity operation, and to anomalies in beam focusing in this configuration. A change to a radial self-field geometry and negative polarity operation resulted in greatly increased beam voltage (> 6 MeV) and estimated ion current. A comprehensive diagnostic set was developed to characterize beam performance, including both time-dependent and time-integrated measurements of local and total beam power. A substantial high-energy ion population was identified propagating in reverse direction, i.e. from the back side of the anode in the electron beam dump. While significant progress was made in increasing beam power, further improvements in assessing the beam focusing envelope will be required before ultimate ion generation efficiency with this geometry can be completely determined.

Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces

Energy Technology Data Exchange (ETDEWEB)

Smith, Alan M. [School of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH (United Kingdom); Paxton, Jennifer Z.; Hung, Yi-Pei; Hadley, Martin J.; Bowen, James; Williams, Richard L. [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom); Grover, Liam M., E-mail: l.m.grover@bham.ac.uk [School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT (United Kingdom)

2015-03-01

Calcium phosphate coatings have been applied to the surface of metallic prostheses to mediate hard and soft tissue attachment for more than 40 years. Most coatings are formed of high purity hydroxyapatite, and coating methods are often designed to produce highly crystalline surfaces. It is likely however, that coatings of lower crystallinity can facilitate more rapid tissue attachment since the surface will exhibit a higher specific surface area and will be considerably more reactive than a comparable highly crystalline surface. Here we test this hypothesis by growing a population of MC3T3 osteoblast-like cells on the surface of two types of hip prosthesis with similar composition, but with differing crystallinity. The surfaces with lower crystallinity facilitated more rapid cell attachment and increased proliferation rate, despite having a less heterogeneous surface topography. This work highlights that the influence of the crystallinity of HA at the nano-scale is dominant over macro-scale topography for cell adhesion and growth. Furthermore, crystallinity could be easily adjusted by without compromising coating purity. These findings could facilitate designing novel coated calcium phosphate surfaces that more rapidly bond tissue following implantation. - Highlights: • Crystallinity of HA at the nano-scale was dominant over macro-scale topography. • Lower crystallinity caused rapid cell attachment and proliferation rate. • Crystallinity could be easily adjusted by without compromising coating purity.

Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces

International Nuclear Information System (INIS)

Smith, Alan M.; Paxton, Jennifer Z.; Hung, Yi-Pei; Hadley, Martin J.; Bowen, James; Williams, Richard L.; Grover, Liam M.

2015-01-01

Calcium phosphate coatings have been applied to the surface of metallic prostheses to mediate hard and soft tissue attachment for more than 40 years. Most coatings are formed of high purity hydroxyapatite, and coating methods are often designed to produce highly crystalline surfaces. It is likely however, that coatings of lower crystallinity can facilitate more rapid tissue attachment since the surface will exhibit a higher specific surface area and will be considerably more reactive than a comparable highly crystalline surface. Here we test this hypothesis by growing a population of MC3T3 osteoblast-like cells on the surface of two types of hip prosthesis with similar composition, but with differing crystallinity. The surfaces with lower crystallinity facilitated more rapid cell attachment and increased proliferation rate, despite having a less heterogeneous surface topography. This work highlights that the influence of the crystallinity of HA at the nano-scale is dominant over macro-scale topography for cell adhesion and growth. Furthermore, crystallinity could be easily adjusted by without compromising coating purity. These findings could facilitate designing novel coated calcium phosphate surfaces that more rapidly bond tissue following implantation. - Highlights: • Crystallinity of HA at the nano-scale was dominant over macro-scale topography. • Lower crystallinity caused rapid cell attachment and proliferation rate. • Crystallinity could be easily adjusted by without compromising coating purity

Streptococcus agalactiae isolates of serotypes Ia, III and V from human and cow are able to infect tilapia.

Science.gov (United States)

Chen, Ming; Wang, Rui; Luo, Fu-Guang; Huang, Yan; Liang, Wan-Wen; Huang, Ting; Lei, Ai-Ying; Gan, Xi; Li, Li-Ping

2015-10-22

Recent studies have shown that group B streptococcus (GBS) may be infectious across hosts. The purpose of this study is to investigate the pathogenicity of clinical GBS isolates with serotypes Ia, III and V from human and cow to tilapia and the evolutionary relationship among these GBS strains of different sources. A total of 27 clinical GBS isolates from human (n=10), cow (n=2) and tilapia (n=15) were analyzed using serotyping, multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Among them, 15 isolates were tested for their pathogenicity to tilapia. The results showed that five human GBS strains (2 serotype III, 2 serotype Ia and 1 serotype V) infected tilapia with mortality rate ranging from 56.67% to 100%, while the other five human GBS strains tested were unable to infect tilapia. In addition, two cow GBS strains C001 and C003 of serotype III infected tilapia. However, they had significantly lower pathogenicity than the five human strains. Furthermore, human GBS strains H005 and H008, which had very strong ability to infect tilapia, had the same PFGE pattern. MLST analysis showed that the five human and the two cow GBS strains that were able to infect tilapia belonged to clonal complexes CC19, CC23 and CC103. The study for the first time confirmed that human or cow GBS clonal complexes CC19, CC23 and CC103 containing strains with serotypes Ia, III and V could infect tilapia and induce clinical signs under experimental conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Interface-Induced Zeeman-Protected Superconductivity in Ultrathin Crystalline Lead Films

Science.gov (United States)

Liu, Yi; Wang, Ziqiao; Zhang, Xuefeng; Liu, Chaofei; Liu, Yongjie; Zhou, Zhimou; Wang, Junfeng; Wang, Qingyan; Liu, Yanzhao; Xi, Chuanying; Tian, Mingliang; Liu, Haiwen; Feng, Ji; Xie, X. C.; Wang, Jian

2018-04-01

Two-dimensional (2D) superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity) in 4-monolayer (ML) to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111) substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.

High-Performance Single-Crystalline Perovskite Thin-Film Photodetector

KAUST Repository

Yang, Zhenqian; Deng, Yuhao; Zhang, Xiaowei; Wang, Suo; Chen, Huazhou; Yang, Sui; Khurgin, Jacob; Fang, Nicholas X.; Zhang, Xiang; Ma, Renmin

2018-01-01

The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial

Characterization of ribonuclease III from Brucella.

Science.gov (United States)

Wu, Chang-Xian; Xu, Xian-Jin; Zheng, Ke; Liu, Fang; Yang, Xu-Dong; Chen, Chuang-Fu; Chen, Huan-Chun; Liu, Zheng-Fei

2016-04-01

Bacterial ribonuclease III (RNase III) is a highly conserved endonuclease, which plays pivotal roles in RNA maturation and decay pathways by cleaving double-stranded structure of RNAs. Here we cloned rncS gene from the genomic DNA of Brucella melitensis, and analyzed the cleavage properties of RNase III from Brucella. We identified Brucella-encoding small RNA (sRNA) by high-throughput sequencing and northern blot, and found that sRNA of Brucella and Homo miRNA precursor (pre-miRNA) can be bound and cleaved by B.melitensis ribonuclease III (Bm-RNase III). Cleavage activity of Bm-RNase III is bivalent metal cations- and alkaline buffer-dependent. We constructed several point mutations in Bm-RNase III, whose cleavage activity indicated that the 133th Glutamic acid residue was required for catalytic activity. Western blot revealed that Bm-RNase III was differently expressed in Brucella virulence strain 027 and vaccine strain M5-90. Collectively, our data suggest that Brucella RNase III can efficiently bind and cleave stem-loop structure of small RNA, and might participate in regulation of virulence in Brucella. Copyright © 2016 Elsevier B.V. All rights reserved.

Bright electroluminescence from a chelate phosphine oxide Eu{sup III} complex with high thermal performance

Energy Technology Data Exchange (ETDEWEB)

Xu Hui [School of Chemistry and Materials, Heilongjiang University, 74 Xuefu Road, Nangang District, Harbin 150080, Heilongjiang Province (China); Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 66 Xinmofan Road, Nanjing 21003, Jiangsu Province (China); Yin Kun; Wang Lianhui [Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 66 Xinmofan Road, Nanjing 21003, Jiangsu Province (China); Huang Wei [Institute of Advanced Materials (IAM), Fudan University, 220 Handan Road, Shanghai 200433 (China)], E-mail: wei-huang@njupt.edu.cn

2008-10-01

The chelate phosphine oxide ligand 1,8-bis(diphenylphosphino)naphthalene oxide (NaPO) was used to prepare complex 1 tris(2-thenoyltrifluoroacetonate)(1,8-bis(diphenylphosphino)naphthalene oxide)europium(III). The rigid structure of NaPO makes 1 have more compact structure resulting in a temperature of glass transition as high as 147 deg. C, which is the highest in luminescent Eu{sup III} complexes, and a higher decomposition temperature of 349 deg. C. The improvement of carrier transfer ability of NaPO was proved by Gaussian simulation. The multi-layered electroluminescent device based on 1 had a low turn-on voltage of 6.0 V, the maximum brightness of 601 cd m{sup -2} at 21.5 V and 481.4 mA cm{sup -2}, and the excellent voltage-independent spectral stability. These properties demonstrated NaPO cannot only be favorable to form the rigid and compact complex structure, and increase the thermal and morphological stability of the complex, but also reduce the formation of the exciplex.

Acousto-optic modulation of III-V semiconductor multiple quantum wells

International Nuclear Information System (INIS)

Smith, D.L.; Kogan, S.M.; Ruden, P.P.; Mailhiot, C.

1996-01-01

We present an analysis of the effect of surface acoustic waves (SAW close-quote s) on the optical properties of III-V semiconductor multiple quantum wells (MQW close-quote s). Modulation spectra at the fundamental and second harmonic of the SAW frequency are presented. The SAW modulates the optical properties of the MQW primarily by changing optical transition energies. The SAW generates both strains, which modulate the transition energies by deformation potential effects, and electric fields, which modulate the transition energies by the quantum confined Stark effect. We find that modulation of the transition energies by strain effects is usually more important than by electric-field effects. If large static electric fields occur in the MQW, the SAW-generated electric field can mix with the static field to give optical modulation, which is comparable in magnitude to modulation from the deformation potential effect. If there are no large static electric fields, modulation by the SAW-generated fields is negligible. A large static electric field distributes oscillator strength among the various optical transitions so that no single transition is as strong as the primary allowed transitions without a static electric field. To achieve the maximum modulation for fixed SAW parameters, it is best to modulate a strong optical transition. Thus optimum modulation occurs when there are no large static electric fields present and that modulation is primarily from deformation potential effects. We specifically consider Ga x In 1-x As/Ga x Al 1-x As MQW close-quote s grown on (100) and (111) oriented substrates, but our general conclusions apply to other type I MQW close-quote s fabricated from III-V semiconductors. copyright 1996 The American Physical Society

Moessbauer investigation of static-disorder crystalline media. V. Hyperfine fields' dispersion in static-disordered crystalline media of tetragonal and trigonal iron germanates

International Nuclear Information System (INIS)

Constantinescu, S.

2007-01-01

The refined 57 Fe Moessbauer spectra of some static-disordered crystalline media (with melilite and Ca-gallate structure) evidenced observable electric and magnetic crystal field dispersions. It is the fifth in a series of papers published previously in the same journal on this subject. The data of crystalline hyperfine fields and their dispersion parameters have calculated using the modeling procedure given in a paper by Kaminskii, et al. published in 1986. The obtained values of the magnetic and quadrupole splitting parameters compared with to experimental data showed the possibility to predict the crystal fields' dispersion. (author)

Determination of As(III and As(V in waters by chronopotentiometric stripping analysis

Directory of Open Access Journals (Sweden)

Švarc-Gajić Jaroslava V.

2006-01-01

Full Text Available Arsenic is a naturally occurring toxic and carcinogenic element. The degree of the toxicity depends on its chemical form and the concentration. Application of a sensitive, selective, simple and rapid method for detection and monitoring of different oxidation states of arsenic in waters is of great importance because main route of population exposure is through drinking water. In this work chronopotentiometric stripping analysis (CSA was used for the determination of As(III and As(V in tap, well, river and rain waters from Vojvodina (Serbia. Gold film electrode on the glassy carbon support was used as the working electrode. The experimental parameters of the technique were investigated and optimized. Detection limit of the method for the electrolysis time of 600 s was 2 μg/dm3 of As(III.

Burnout in boiling heat transfer. Part III. High-quality forced-convection systems

International Nuclear Information System (INIS)

Bergles, A.E.

1979-01-01

This is the final part of a review of burnout during boiling heat transfer. The status of burnout in high-quality forced-convection systems is reviewed, and recent developments are summarized in detail. A general guide to the considerable literature is given. Parametric effects and correlations for water in circular and noncircular ducts are presented. Other topics discussed include transients, steam-generator applications, correlations for other fluids, fouling, and augmentation

POPULATION III STARS AND REMNANTS IN HIGH-REDSHIFT GALAXIES

International Nuclear Information System (INIS)

Xu Hao; Norman, Michael L.; Wise, John H.

2013-01-01

Recent simulations of Population III star formation have suggested that some fraction form in binary systems, in addition to having a characteristic mass of tens of solar masses. The deaths of metal-free stars result in the initial chemical enrichment of the universe and the production of the first stellar-mass black holes. Here we present a cosmological adaptive mesh refinement simulation of an overdense region that forms a few 10 9 M ☉ dark matter halos and over 13,000 Population III stars by redshift 15. We find that most halos do not form Population III stars until they reach M vir ∼ 10 7 M ☉ because this biased region is quickly enriched from both Population III and galaxies, which also produce high levels of ultraviolet radiation that suppress H 2 formation. Nevertheless, Population III stars continue to form, albeit in more massive halos, at a rate of ∼10 –4 M ☉ yr –1 Mpc –3 at redshift 15. The most massive starless halo has a mass of 7 × 10 7 M ☉ , which could host massive black hole formation through the direct gaseous collapse scenario. We show that the multiplicity of the Population III remnants grows with halo mass above 10 8 M ☉ , culminating in 50 remnants located in 10 9 M ☉ halos on average. This has implications that high-mass X-ray binaries and intermediate-mass black holes that originate from metal-free stars may be abundant in high-redshift galaxies

Significantly improved surface morphology of N-polar GaN film grown on SiC substrate by the optimization of V/III ratio

Science.gov (United States)

Deng, Gaoqiang; Zhang, Yuantao; Yu, Ye; Yan, Long; Li, Pengchong; Han, Xu; Chen, Liang; Zhao, Degang; Du, Guotong

2018-04-01

In this paper, N-polar GaN films with different V/III ratios were grown on vicinal C-face SiC substrates by metalorganic chemical vapor deposition. During the growth of N-polar GaN film, the V/III ratio was controlled by adjusting the molar flow rate of ammonia while keeping the trimethylgallium flow rate unchanged. The influence of the V/III ratio on the surface morphology of N-polar GaN film has been studied. We find that the surface root mean square roughness of N-polar GaN film over an area of 20 × 20 μm2 can be reduced from 8.13 to 2.78 nm by optimization of the V/III ratio. Then, using the same growth conditions, N-polar InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) were grown on the rough and the smooth N-polar GaN templates, respectively. Compared with the LED grown on the rough N-polar GaN template, dramatically improved interface sharpness and luminescence uniformity of the InGaN/GaN MQWs are achieved for the LED grown on the smooth N-polar GaN template.

Postradiation reactions of free radicals in crystalline carbohydrates

International Nuclear Information System (INIS)

Yudin, I.V.; Filyanin, G.A.; Panasyuk, S.L.

1990-01-01

In order to determine the nature of the elementary stages of chain process of formation of molecular products in irradiated carbohydrates, the kinetics of their accumulation in crystalline matrices at 100-400 K were investigated. Chain formation of carbonyl products in xylose crystals irradiated at 100 K was identified at temperatures above 240 K and in saccharose, rhamnose, and arabinose crystals at T > 273 K. Chain formation of hydroxy acids with a radiochemical yield of ∼ 150 molecules/100 eV was confirmed in crystalline lactose

On the use of the plasma in III-V semiconductor processing

Energy Technology Data Exchange (ETDEWEB)

Bruno, G.; Capezzuto, P.; Losurdo, M. [C.N.R.-Centro di Studio per la Chimica dei Plasmi Dipartimento di Chimica-Universita di Bari via Orabona, 4-70126 Bari (Italy)

1996-03-01

The manufacture of usable devices based on III-V semiconductor materials is a complex process requiring epilayer growth, anisotropic etching, defect passivation, surface oxidation and substrate preparation processes. The combination of plasma based methods with metalorganic chemical vapor deposition (MOCVD) offers some real advantages: {ital in} {ital situ} production and preactivation of PH{sub 3} and sample preparation using H-atom. The detailed understanding and use of the plasma (using mass spectrometry, optical emission spectroscopy, laser reflectance interferometry and spectroscopic ellipsometry) as applied to InP material is discussed. {copyright} {ital 1996 American Institute of Physics.}

Human Retroviruses and AIDS. A compilation and analysis of nucleic acid and amino acid sequences: I--II; III--V

Energy Technology Data Exchange (ETDEWEB)

Myers, G.; Korber, B. [eds.] [Los Alamos National Lab., NM (United States); Wain-Hobson, S. [ed.] [Laboratory of Molecular Retrovirology, Pasteur Inst.; Smith, R.F. [ed.] [Baylor Coll. of Medicine, Houston, TX (United States). Dept. of Pharmacology; Pavlakis, G.N. [ed.] [National Cancer Inst., Frederick, MD (United States). Cancer Research Facility

1993-12-31

This compendium and the accompanying floppy diskettes are the result of an effort to compile and rapidly publish all relevant molecular data concerning the human immunodeficiency viruses (HIV) and related retroviruses. The scope of the compendium and database is best summarized by the five parts that it comprises: (I) HIV and SIV Nucleotide Sequences; (II) Amino Acid Sequences; (III) Analyses; (IV) Related Sequences; and (V) Database Communications. Information within all the parts is updated at least twice in each year, which accounts for the modes of binding and pagination in the compendium.

Spectrophotometric and potentiometric studies of oxidation of Mo(III) by Mo(VI) in phosphoric acid medium

Energy Technology Data Exchange (ETDEWEB)

Kumar, A; Verma, G S.P. [Ranchi Coll. (India). Dept. of Chemistry

1975-12-01

Oxidation of Mo(III) (green) by Mo(VI) in an inert atmosphere and in orthophosphoric acid medium at various acid concentrations is reported. Potentiometric and spectrophotometric data suggest that oxidation of Mo(III) proceeds to Mo(V) through a binuclear species Mo(III) Mo(IV) absorbing at 400 nm. The formation of this species is facilitated at high acid concentrations. It is further found that quantitative conversion of Mo(III) into Mo(V) takes place at fairly high acid concentrations. In high phosphoric acid concentrations, solution of Mo(III) has been found to be oxidized to Mo(VI) by air and hence this can be used as a good oxygen absorber.

Solvent-free directed patterning of a highly ordered liquid crystalline organic semiconductor via template-assisted self-assembly for organic transistors.

Science.gov (United States)

Kim, Aryeon; Jang, Kwang-Suk; Kim, Jinsoo; Won, Jong Chan; Yi, Mi Hye; Kim, Hanim; Yoon, Dong Ki; Shin, Tae Joo; Lee, Myong-Hoon; Ka, Jae-Won; Kim, Yun Ho

2013-11-20

Highly ordered organic semiconductor micropatterns of the liquid-crystalline small molecule 2,7-didecylbenzothienobenzothiophene (C10 -BTBT) are fabricated using a simple method based on template-assisted self-assembly (TASA). The liquid crystallinity of C10 -BTBT allows solvent-free fabrication of high-performance printed organic field-effect transistors (OFETs). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystallinity and flux pinning properties of MgB2 bulks

International Nuclear Information System (INIS)

Yamamoto, A.; Shimoyama, J.; Ueda, S.; Katsura, Y.; Iwayama, I.; Horii, S.; Kishio, K.

2006-01-01

The relationship between flux pinning properties and crystallinity of MgB 2 bulks was systematically studied. Improved flux pinning properties under high fields were observed for samples with low crystallinity. Increased impurity scattering due to strain and defects in lattice corresponding to the degraded crystallinity was considered to enhance flux pinning strength at grain boundaries. Low-temperature synthesis and carbon substitution were confirmed to be effective for degrading crystallinity of MgB 2 bulks, resulting in high critical current properties under high fields

Diffusion of Lithium Ions in Amorphous and Crystalline Poly(ethylene oxide)_3:LiCF_3SO_3 Polymer Electrolytes

International Nuclear Information System (INIS)

Xue, Sha; Liu, Yingdi; Li, Yaping; Teeters, Dale; Crunkleton, Daniel W.; Wang, Sanwu

2017-01-01

The PEO_3:LiCF_3SO_3 polymer electrolyte has attracted significant research due to high conductivity and enhanced stability in lithium polymer batteries. Most experimental studies have shown that amorphous PEO lithium salt electrolytes have higher conductivity than the crystalline ones. Other studies, however, have shown that crystalline PEO salt complexes can conduct ions. As a result, further theoretical investigations are warranted to help clarify the issue. In this work, we use density functional theory with the climbing image nudged elastic band method to investigate the atomic-scale mechanism of lithium ion transport in the polymer electrolytes. We also use density functional theory and ab initio molecular dynamics simulations to obtain the amorphous structure of PEO_3:LiCF_3SO_3. The diffusion pathways and activation energies of lithium ions in both crystalline and amorphous PEO_3:LiCF_3SO_3 are determined. In crystalline PEO_3:LiCF_3SO_3, the activation energy for the low-barrier diffusion pathway is approximately 1.0 eV. In the amorphous phase, the value is 0.6 eV. This result would support the experimental observation that amorphous PEO_3:LiCF_3SO_3 has higher ionic conductivity than the crystalline phase.

Crystalline and Crystalline International Disposal Activities

Energy Technology Data Exchange (ETDEWEB)

Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-12-21

This report presents the results of work conducted between September 2014 and July 2015 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program.

High-quality InN films on MgO (100) substrates: The key role of 30° in-plane rotation

Energy Technology Data Exchange (ETDEWEB)

Compeán García, V. D.; López Luna, E.; Rodríguez, A. G.; Vidal, M. A. [Coordinación para la Innovación y Aplicación de la Ciencia y Tecnología (CIACyT), Universidad Autónoma de San Luis Potosí (UASLP), Álvaro Obregón 64, 78000 San Luis Potosí (Mexico); Orozco Hinostroza, I. E. [Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4a Sección, 78216 San Luis Potosí (Mexico); Escobosa Echavarría, A. [Electric Engineering Department, Centro de Investigación y Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 México D.F. (Mexico)

2014-05-12

High crystalline layers of InN were grown on MgO(100) substrates by gas source molecular beam epitaxy. Good quality films were obtained by means of an in-plane rotation process induced by the annealing of an InN buffer layer to minimize the misfit between InN and MgO. In situ reflection high-energy electron diffraction showed linear streaky patterns along the [011{sup ¯}0] azimuth and a superimposed diffraction along the [112{sup ¯}0] azimuth, which correspond to a 30° α-InN film rotation. This rotation reduces the mismatch at the MgO/InN interface from 19.5% to less than 3.5%, increasing the structural quality, which was analyzed by high-resolution X-ray diffraction and Raman spectroscopy. Only the (0002) c plane diffraction of α-InN was observed and was centered at 2θ = 31.4°. Raman spectroscopy showed two modes corresponding to the hexagonal phase: E1(LO) at 591 cm{sup −1} and E2(high) at 488 cm{sup −1}. Hall effect measurements showed a carrier density of 9 × 10{sup 18} cm{sup −3} and an electron Hall mobility of 340 cm{sup 2}/(V s) for a film thickness of 140 nm.