bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on Ultrasound‐ and Spray‐Assisted Precipitation of CL‐20
Authors: Wang Jingyu , Li Junlong , An Chongwei , Hou Conghua , Xu Wenzheng , Li Xiaodong 
Published: June 2012

AbstractUltrafine hexanitrohexaazaisowurtzitane (CL‐20) samples were prepared by a ultrasound‐ and spray‐assisted precipitation method. Raw CL‐20 and ultrafine CL‐20 samples were characterized by SEM, FT‐IR spectroscopy, XRD, and particle size analysis. The impact sensitivity and thermal stability of two CL‐20 samples were also tested and compared. The results indicate that by this recrystallization process, the mean particle size of CL‐20 is 470 nm, and the particle size distribution was in the range from 400–700 nm. The particle morphology is nearly spheric with a smooth surface. Compared with raw CL‐20, the impact sensitivity of the ultrafine sample is significantely reduced and the drop height (H50) is increased from 12.8 to 37.9 cm. The critical explosion temperature of ultrafine CL‐20 decreased from 235.6 to 229.0 °C, which suggests that the thermal stability of ultrafine CL‐20 is lower than that of raw CL‐20.
Thermal and Combustion Properties of 3,4‐Bis(3‐nitrofurazan‐4‐yl)furoxan (DNTF)
Authors: Sinditskii Valery P. , Burzhava Anna V. , Sheremetev Aleksey B. , Aleksandrova Natalia S. 
Published: June 2012

AbstractThermal decomposition of melted 3,4‐bis(3‐nitrofurazan‐4‐yl)furoxan (DNTF) in isothermal conditions was studied. The burning rates of DNTF were measured in the pressure interval of 0.1–15 MPa. The thermal stability of DNTF was found to be close to the stability of HMX, while the burning rate of DNTF was close to the burning rate of CL‐20. The thermocouple measurements in the combustion wave of DNTF showed that combustion of DNTF was controlled by the gas‐phase mechanism. The DNTF vapor pressure was determined from thermocouple measurements and agreed well with data obtained at low temperatures under isothermal conditions.
Computer Simulation of Decomposition Mechanisms for CL‐20, Hydrazine, and Their Binary System
Authors: Pivina Tatyana , Korolev Vyacheslav , Khakimov Dmitriy , Petukhova Tatyana , Ivshin Victor , Lempert David 
Published: June 2012

AbstractAn approach to simulate thermal destruction processes of energetic materials has been developed. It is based on the classification of structural features for nitro compounds and the experimental data regarding their decomposition mechanisms. This approach consists of the mathematical simulation of thermal decomposition mechanisms to predict the likely reactions that may occur during the destruction of organic compounds. On the basis of contemporary experimental data on the decomposition of energetic materials from various chemical classes, a set of semi‐empirical rules for modeling possible reaction pathways has been formulated. These rules allow the generation of a whole set of possible decomposition mechanisms for substances at different steps of their destruction. In this study, the suggested methodology is applied to 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20) and hydrazine and to their binary energetic mixture. It has been shown that thermal decomposition of the binary system consists in decompositions of the separate compounds at the initial stage with subsequent collisions and interactions of the resultant intermediates and decomposition products at different stages. In addition to some experimentally found decomposition products, our simulation showed some other possible compounds among the final products.
Synthesis and Characterization of 1‐Nitroguanyl‐3‐nitro‐5‐amino‐1,2,4‐triazole
Authors: Chavez David E. , Parrish Damon A. 
Published: June 2012

AbstractThe synthesis of 1‐nitroguanyl‐3‐nitro‐5‐amino‐1,2,4‐triazole (ANTA‐NQ) (1) with good yield and high purity is described. DSC analysis showed that the material displays good thermal stability. An X‐ray crystallographic analysis confirms the structure of this material, as well as displays intramolecular hydrogen bonding. A gas pycnometry density for this material was measured to be 1.79 g cm−3. The heat of formation of this material was also measured. These data, along with the molecular formula were used as inputs to calculate the detonation velocity and detonation pressure using the Cheetah thermochemical code. The sensitivity of this material towards impact, spark and friction was also measured, as well as its vacuum thermal stability. The 3‐azido derivative 2 was also prepared and its properties are described as well. The above data show that (ANTA‐NQ) may be a high performing material with low sensitivity and good thermal stability.
Primary androgen deprivation (AD) followed by active surveillance (AS) for newly diagnosed prostate cancer (PC): A retrospective study
Authors: Scholz Mark C. , Groom Meg K. , Kaddis Andrew J. , Strum Stephen B. , Jennrich Robert I. , Bahn Duke K. , Chang Patricia J. , Becker Lauren K. , Lam Richard Y. 
Published: July 2012

AbstractBACKGROUNDActive surveillance (AS) is only recommended for Low‐Risk prostate cancer (PC) with <34% biopsies positive. Studies describing the long‐term outcome of men treated with androgen deprivation (AD) followed by AS are sparse.MATERIALS AND METHODSOne hundred two men were treated with 12 months of AD in a medical oncology clinic specializing in PC between 1998 and 2007 and were followed for a median of 7.25 years. The biopsy complete response rate after AD and the incidence of disease progression while on subsequent AS was assessed. Baseline age, D'Amico risk category, PSA velocity, percentage core biopsies, and prostate volume were evaluated as potential predictors of disease progression.RESULTSD'Amico risk category for the 102 men: Low: n = 22, Intermediate: n = 30, and High: n = 50. Medians: Age 67.3, PSA 7.8, Gleason 3 + 4, >50% core biopsies positive, stage T1c. Seventy men had a clear biopsy and 31 of these had disease progression leading to additional treatment after a median of 52 months. D'Amico risk category of the 57 men with a positive biopsy after AD or disease progression on AS was: Low: n = 4 (18%), Intermediate: n = 16 (53%), and High: n = 37 (74%). No PC deaths occurred. Three men had clinical progression. In stepwise logistic regression analysis only higher D'Amico risk category and lower prostate volume predicted disease progression.CONCLUSIONSDespite a high prevalence of ≥50% core biopsies positive at baseline, AD induces durable remissions in most men with Low‐Risk and about half with Intermediate‐Risk PC. Prostate 73: 83–88, 2013. © 2012 Wiley Periodicals, Inc.
MBE growth and design of II–VI heterostructures for epitaxial lift‐off
Authors: Davidson Ian A. , Moug Richard T. , Vallance Erin C. , Tamargo Maria C. , Prior Kevin A. 
Published: June 2012

AbstractEpitaxial lift‐off (ELO) is a post‐growth process that allows the active part of a semiconductor structure to be transferred from its growth substrate to a new one. This is a well established technique for III–V semiconductors, and has previously been demonstrated for ZnSe‐based alloys grown on GaAs using a metastable MgS sacrificial layer, taking advantage of the huge difference in etch rates of MgS and ZnSe.We report here the first successful extension of this process to II–VI layers grown on InP by using a MgSe sacrificial layer. By using the correct etching conditions, MgSe has been found to work effectively as a sacrificial layer. 5 × 5 mm2 square pieces of material can be lifted and deposited on glass substrates without any deterioration in the structural or optical properties; as confirmed by optical microscopy and photoluminescence (PL) measurements.
Mechanical energy losses in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum at elevated temperatures
Authors: Zelada Griselda I. , Lambri Osvaldo Agustin , Bozzano Patricia B. , García José Angel 
Published: June 2012

AbstractMechanical spectroscopy (MS) and transmission electron microscopy (TEM) studies have been performed in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum, oriented for single slip, in order to study the dislocation dynamics in the temperature range within one third of the melting temperature. A damping peak related to the interaction of dislocation lines with both prismatic loops and tangles of dislocations was found. The peak temperature ranges between 900 and 1050 K, for an oscillating frequency of about 1 Hz.
The effect of synthesis parameters on transport properties of nanostructured bulk thermoelectric p‐type silicon germanium alloy
Authors: Zamanipour Zahra , Shi Xinghua , Dehkordi Arash M. , Krasinski Jerzy S. , Vashaee Daryoosh 
Published: June 2012

AbstractNanostructured silicon germanium thermoelectric materials prepared by mechanical alloying and sintering method have recently shown large enhancement in figure‐of‐merit, ZT. The fabrication of these structures often involves many parameters whose understanding and precise control is required to attain large ZT. In order to find the optimum parameters for further enhancing the ZT of this material, we have grown and studied both experimentally and theoretically different nanostructured p‐type SiGe alloys. The effect of various parameters of milling process and sintering conditions on the thermoelectric properties of the grown samples were studied. The electrical and thermal properties were calculated using Boltzmann transport equation and were compared with the data of nanostructured and crystalline SiGe. It was found that the thermal conductivity not only depends on the average crystallite size in the bulk material, but also it is a strong function of alloying, porosity, and doping concentration. The Seebeck coefficient showed weak dependency on average crystallite size. The electrical conductivity changed strongly with synthesis parameters. Therefore, depending on the synthesis parameters the figure‐of‐merit reduced or increased by ∼60% compared with that of the crystalline SiGe. The model calculation showed that the lattice part of thermal conductivity in the nanostructured sample makes ∼80% of the total thermal conductivity. In addition, the model calculation showed that while the room temperature hole mean free path (MFP) in the nanostructured sample is dominated by the crystallite boundary scattering, at high temperature the MFP is dominated by acoustic phonon scattering. Therefore, the thermal conductivity can be further reduced by smaller crystallite size without significantly affecting the electrical conductivity in order to further enhance ZT.
Effects of substrate temperature upon optical properties of ZnTe epilayers grown on (100) GaAs substrates by MOVPE
Authors: Huang Shulai , Ji Ziwu , Zhao Mingwen , Zhang Lei , Guo Hongyu , Liu Baoli , Xu Xiangang , Guo Qixin 
Published: June 2012

AbstractThe photoluminescence (PL) properties of the ZnTe epilayers grown on (100) GaAs substrates with various substrate temperatures have been investigated. It has been demonstrated that the PL spectra depend strongly on the substrate temperature. A too low (390 °C) or too high (440 °C) substrate temperature deteriorates the epilayer quality due to the formation of defects or/and to the inclusion of impurities. A moderate substrate temperature (around 420 °C) is suitable to obtain a high‐quality epilayer with the narrow spectral width and strong emission intensity. This is attributed to the moderate substrate temperature improving the crystallinity of the ZnTe epilayer by enhancing recrystallization of the adsorbed precursors.
Understanding and morphology control of pore modulations in nanoporous anodic alumina by discontinuous anodization
Authors: Santos Abel , Vojkuvka Lukas , Alba María , Balderrama Victor S. , Ferré‐Borrull Josep , Pallarès Josep , Marsal Lluís F. 
Published: June 2012

AbstractHere, we report on an electrochemical approach so‐called discontinuous anodization (DA) for controlling the generation of pore modulations in nanoporous anodic alumina (NAA) under self‐ordering conditions. In this method, the anodization of aluminium is performed by voltage pulses under mild anodization regime and thermal‐acidic conditions. Furthermore, we perform an exhaustive and systematic study about the relationship between the pore modulation morphology and the main anodization parameters (i.e. acid electrolyte temperature and relax time between consecutive voltage pulses). The generation mechanism of the pore modulations is associated with the formation of a gel‐like layer under these thermal‐acidic conditions and its subsequent detachment during the beginning of each voltage pulse. All this makes it possible to control the pore modulation morphology in NAA at will, what is crucial for developing new nanostructures with accurately controlled geometry for such purposes as nanofluidics, magnetic nanostructures, optical biosensors, templates, selective molecular separators and so forth. magnified image
A three‐dimensional network based on NAA with controlled geometry: The DA by voltage pulses under hydrothermal conditions yields an accurate control over the pore modulation morphology. Therefore, the structure of the resulting 3D‐NAA network can be designed at will for later applications.
Carbon‐nanotube‐based flexible devices using a mechanical transfer method
Authors: Lee Kyongsoo , Ju Byeong‐Kwon 
Published: June 2012

AbstractWe describe a new method for the manufacture of single‐walled carbon nanotube (SWCNT)‐based electrical devices on flexible substrates. The method involves the deposition of a SWCNT films onto polydimethylsiloxane (PDMS) substrates from rigid substrates using the adhesive property of PDMS. This method is similar to the conventional dry transfer method, which is based on surface‐energy modification, except that our method involves mechanical transfer using the adhesive property of PDMS under peculiar conditions. The gas‐sensing characteristics of the resulting transferred SWCNT films are presented, showing, for example, that typical flexible sensors exhibit a sensitivity of 17.4% for 4‐ppm NO2 in a vacuum at room temperature. The performances of the devices are slightly reduced when they are bent to a curved profile with a bending radius of 2 cm (15.9%). The field‐emission properties are also investigated. From these emitters, the SWCNTs can be turned on with a field as low as 0.9 V/µm, and an emission current density of 0.75 mA/cm2 at 1.2 V/µm can be attained. Thus, a method for the fabrication of flexible devices is established, which should find practical applications in electronic devices.
Correlation Study Using Scuffing Damage to Investigate Improved Simulation Techniques for Packaging Vibration Testing
Authors: Griffiths K. , Shires D. , White W. , Keogh P. S. , Hicks B. J. 
Published: July 2012

Vibration testing of packaging is a critical part of the distribution packaging analysis process. The accuracy of simulated vibration is important for packaging optimization. Because of this, several researchers have developed improved simulation methods to produce more realistic vibration tests. Correlation studies are required to verify these methods, ideally using actual packaged products in transit. Unfortunately, cost, time and complexity issues make carrying out studies with actual product difficult.This article uses a specially designed and proven test rig, which simulates the damage mechanism of scuffing, to carry out a correlation study. The study compares the level of damage produced when performing simulations using a range of improved techniques in comparison with the time‐history reproduction of a journey (used as a benchmark) and the established method using the average power density spectrum to create a Gaussian simulation signal.The level of scuffing damage produced varied between the different simulation methods, with the modulated root mean square (RMS) technique and the accelerated power density spectrum (with a time compression of 5 and a k equal to 2) best reproducing the level of damage observed from the benchmark time replication test. Copyright © 2012 John Wiley & Sons, Ltd.
Longitudinal localization of tropical intraseasonal variability
Authors: Sukhatme Jai 
Published: June 2012

AbstractIntraseasonal time‐scales play an important role in tropical variability. Two modes that contribute significantly to tropical intraseasonal variability (ISV) are the eastward‐propagating Madden–Julian Oscillation (MJO), and westward‐moving moist equatorial Rossby waves. This note reports on a correspondence between the longitudinal gradient of mean tropical precipitable water (PW), and the geographical regions of genesis, and convective activity, of both these large‐scale tropical systems. Our finding is based on an analysis of PW from the MERRA reanalysis product. The data indicate that the mean tropical PW has a dominant wavenumber two (three) structure in longitude in the Northern (Southern) Hemisphere. Departures from a longitudinally homogeneous state are attributed to the influence of subtropical anticyclones, and are accentuated by monsoonal regions of both hemispheres. This mean structure results in a sharply localized longitudinal gradient of PW. Remarkably, regions with positive gradients (such as the Northern and Southern Hemisphere western Indian Ocean), i.e. they have larger PW to the east, are the very zones that are implicated in the formation, and show high levels of convective activity, of the eastward‐moving MJO. On the other hand, regions with negative gradients (such as the Southern Hemisphere central Pacific) are the very regions where genesis, and maxima in variance, of westward‐moving moist equatorial Rossby waves are known to occur. Apart from providing a first‐order longitudinal footprint of the convective phase of these systems, this correspondence reinforces the role of the mean climatic state in tropical ISV. Copyright © 2012 Royal Meteorological Society
A four‐dimensional asynchronous ensemble square‐root filter (4DEnSRF) algorithm and tests with simulated radar data
Authors: Wang Shizhang , Xue Ming , Min Jinzhong 
Published: June 2012

AbstractA four‐dimensional ensemble square‐root filter algorithm (4DEnSRF) is designed to assimilate high‐frequency asynchronous observations distributed over time. Given the serial nature of the EnSRF, the 4DEnSRF algorithm pre‐calculates observation priors from ensemble model states at observation times and updates the observation priors at asynchronous observational times using the filter. These updated observation posteriors are used to update model state variables at the analysis time. Such an algorithm is able to utilize more observations collected over time with fewer analysis cycles, thereby reducing computational costs and potentially improving filter performance. The 4DEnSRF algorithm is tested using simulated Doppler radar data for a convective storm. The radar data are simulated elevation‐by‐elevation, grouped into batches with different time intervals and then assimilated with analysis cycles of the same lengths. Parallel sets of experiments using 4DEnSRF and the regular EnSRF are performed for comparison, with varying data batch or cycle lengths of 1 to 20 min. For longer time intervals, EnSRF either assumes that all data collected within the time window are valid at the same analysis time, or uses only elevations collected within a shorter time interval centered at the analysis time. Results show that 4DEnSRF outperforms EnSRF when the cycle length is more than 1 min. Observation timing error is the main cause of the performance degradation with EnSRF for both analysis and forecast; the longer the cycle length, the worse the degradation. For long cycle lengths, 4DEnSRF improves the analysis by utilizing more data whereas the EnSRF performs well only when data far away from the analysis time are discarded. Assimilating only a couple of scan elevations at a time using EnSRF with very short cycles can introduce imbalances into the model state that degrades the subsequent analyses and forecasts. Copyright © 2012 Royal Meteorological Society
Comparison of zinc and magnesium clusters in their reaction with organochlorides: Toward a molecular picture of grignard reagent formation
Authors: Barsukov Yu. V. , Porsev V. V. , Tulub A. V. 
Published: June 2012

AbstractThe reaction channels of Znn and Mgn clusters (n = 4, 10) with RCl organochlorides are compared to the investigation of relative activity of metals in the reaction of Grignard reagent formation within a framework of quantum chemical modeling of a reaction path. R radicals are chosen from a list of alkyl (CH3, C2H5, i‐C3H7, and t‐C4H9) and residues with π‐bond (C2H3 and C6H5). Quantum chemistry calculations are made using the density function theory (DFT) approach at the B3PW91/6‐311+G(d) level. The reaction channels for both zinc and magnesium can be classified as radical and nonradical according to the nature of reaction products. The calculation of activation energies shows much similarity in their dependence on the nature of R radical but in the case of zinc, barriers are significantly higher. Both for zinc and magnesium clusters, the radical channels are more preferable in the case of alkyl residues, for vinyl and phenyl residues barriers of radical and nonradical channels are comparable. © 2012 Wiley Periodicals, Inc.
Calculations of structures and reaction energy profiles of As2O3 and As4O6 species by quantum chemical methods
Authors: da Hora Gabriel Costa A. , Longo Ricardo L. , da Silva João Bosco P. 
Published: June 2012

AbstractPrincipal component analysis was used in the selection of the B3PW91/6‐311+G(3df) method for calculations of As2O3 molecular species. This multivariate analysis compared experimental properties (structure and ionization energy) of As4O6 molecule with several computational methods (Hartree–Fock, second‐order Møller–Plesset perturbation theory, and density functional theory) and basis sets. At the selected level of theory, we were able to calculate nine structures of As2O3 with three of them being stable ones (no negative force constants) in the following stability order: D3H (0.0), DIAMOND OUT (32.77 kJ mol−1), and GAUCHE (43.81 kJ mol−1). Several intramolecular conversions were studied with the GAUCHE → DIAMOND OUT transformation being barrierless, whereas the DIAMOND OUT structure is converted into the D3H isomer through a Gibbs free‐energy barrier of 40.83 kJ mol−1. Starting from the GAUCHE structure of As2O3 and its enantiomeric form, it was possible to obtain directly (barrierless) the As4O6 species in a spontaneous process (ΔrG = −399.92 kJ mol−1 at 298 K and 1 atm) in gas phase. Thus, the As4O6 species is probably the precursor of arsenic hydroxide through hydrolysis reactions. © 2012 Wiley Periodicals, Inc.
Vertical triple ionization with diffusion quantum monte carlo
Authors: Angelotti W. F. D. , Batista W. R. , Granato A. C. 
Published: June 2012

AbstractThe vertical triple ionization potential is calculated using the diffusion quantum Monte Carlo (DQMC) method for several states of the water molecule. The results are in good agreement with theoretical data presented in the literature. The results demonstrate that the DQMC method is capable of balancing the effects of relaxation and electronic correlation. © 2012 Wiley Periodicals, Inc.