bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diastereoselective Synthesis of (Aryloxy)phosphoramidate Prodrugs
Authors: Arbelo Román Cristina , Wasserthal Philip , Balzarini Jan , Meier Chris 
Published: July 2011

AbstractThe first diastereoselective synthesis of aryloxyphosphoramidate prodrugs of 3′‐deoxy‐2′,3′‐didehydrothymidinemonophosphate (d4TMP) was recently reported. The synthetic approach utilized the chiral auxiliary (S)‐4‐isopropylthiazolidine‐2‐thione (2). For this strategy, a stereochemically pure phosphorodiamidate intermediate was needed. The diastereoselective formation of this key compound was investigated by using different phenols and L‐alanine methyl or benzyl ester. Generally, the reaction with 3‐ or 4‐substituted phenols led to significantly better diastereoselectivities compared to their 2‐substituted counterparts. Moreover, variation of the ester group in the amino acid residue resulted in no significant differences with regard to the obtained diastereoselectivity. From the reported results, a model for the transition state was elaborated. Finally, eight new (SP)‐arylphosphoramidates were synthesized with very high diastereoselectivities (up to ≥ 95 % de) and tested for their anti‐HIV potency, showing a tendency for higher antiviral activity from the (SP) diastereomers.
Mass‐Transfer Admittance Voltammetry from Electrochemical Impedance Spectroscopy and Its Applications
Authors: Chang Byoung‐Yong , Lee Hyo Joong , Park Su‐Moon 
Published: July 2011

AbstractWe report an extraction‐reconstruction strategy for obtaining a novel voltammogram for a specific electrochemical process. While a conventional voltammogram is obtained from potentiodynamic currents, our voltammogram is obtained from a large body of potentiodynamic electrochemical impedance spectra by taking advantage of their highly resolvable power. As a proof of concept, construction of a mass transfer admittance voltammogram (MTAV) is demonstrated, which is made up of purely mass transfer admittances plotted vs. potential, excluding effects from other interfering electrochemical components. We also compare the MTAV with the AC voltammogram to show its enhanced accuracy and apply the novel voltammetry to clearly determine the number of electrons transferred and diffusion coefficients, which may vary depending on experimental conditions, for a complex electrochemical reaction.
Preparation and Electrochemical Properties of Graphene‐Modified Electrodes for All‐Vanadium Redox Flow Batteries
Authors: Tsai Han‐Min , Yang Shin‐Yi , Ma Chen‐Chi M. , Xie Xiaofeng 
Published: July 2011

AbstractThe electrochemical properties of graphene make it an attractive material for use in a range of devices. We herein describe the simple preparation of graphene‐modified graphite (GMG) composite electrodes by hybridization with graphite for all‐vanadium redox flow batteries (VRB). The cyclic voltammetry (CV) results revealed that the use of GMG composite electrodes with an optimal graphene loading content (3 wt%) allowed remarkable improvements in terms of both the reversibility and the current density, which was up to 30 % higher than that of the pristine graphite electrode, and that an electrode of this type shows considerable potential for use in VRBs.
Comparison of brain mitochondrial cytochrome c oxidase activity with cyanide LD50 yields insight into the efficacy of prophylactics
Authors: Marziaz Mandy L. , Frazier Kathryn , Guidry Paul B. , Ruiz Robyn A. , Petrikovics Ilona , Haines Donovan C. 
Published: July 2011

ABSTRACTCyanide inhibits cytochrome c oxidase, the terminal oxidase of the mitochondrial respiratory pathway, therefore inhibiting the cell oxygen utilization and resulting in the condition of histotoxic anoxia. The enzyme rhodanese detoxifies cyanide by utilizing sulfur donors to convert cyanide to thiocyanate, and new and improved sulfur donors are actively sought as researchers seek to improve cyanide prophylactics. We have determined brain cytochrome c oxidase activity as a marker for cyanide exposure for mice pre‐treated with various cyanide poisoning prophylactics, including sulfur donors thiosulfate (TS) and thiotaurine (TT3). Brain mitochondria were isolated by differential centrifugation, the outer mitochondrial membrane was disrupted by a maltoside detergent, and the decrease in absorbance at 550 nm as horse heart ferrocytochrome c (generated by the dithiothreitol reduction of ferricytochrome c) was oxidized was monitored. Overall, the TS control prophylactic treatment provided significant protection of the cytochrome c oxidase activity. The TT3‐treated mice showed reduced cytochrome c oxidase activity even in the absence of cyanide. In both treatment series, addition of exogenous Rh did not significantly enhance the prevention of cytochrome c oxidase inhibition, but the addition of sodium nitrite did. These findings can lead to a better understanding of the protection mechanism by various cyanide antidotal systems. Copyright © 2011 John Wiley & Sons, Ltd.
Treatment of comorbid posttraumatic stress disorder and major depressive disorder: A pilot study
Authors: Nixon Reginald D. V. , Nearmy Danielle M. 
Published: July 2011

AbstractThe efficacy of a cognitive–behavioral treatment program for individuals with comorbid posttraumatic stress disorder (PTSD) and major depression (MDD) was examined. In an uncontrolled pre‐ and posttreatment study, participants attended 12–16 weeks of manualized therapy incorporating behavioral activation for depression in early sessions and exposure therapy and cognitive restructuring for PTSD in later sessions. Fourteen participants (of 20) completed treatment. Results indicated a significant decrease in PTSD and depression severity between pre‐ and midtreatment assessments; PTSD decreased further from mid‐ to posttreatment. Treatment gains were maintained at 3‐month follow‐up; 60% of participants no longer met PTSD criteria at 3‐month follow‐up, and 70% no longer met MDD criteria. The clinical implications of this phased approach to treat PTSD and depression comorbidity are discussed.
The relationship between interpersonal traits and posttraumatic stress disorder symptoms: Analyses from Wenchuan earthquake adolescent survivors in China
Authors: Xia Ling‐Xiang , Ding Cody 
Published: July 2011

AbstractThis study explores the relationship between interpersonal traits and posttraumatic stress disorder (PTSD) symptoms in a sample of 617 middle and high school students 16 months after the Wenchuan earthquake in China using the Impact of Event Scale‐Revised (IES‐R) and the Interpersonal Self‐Supporting Scale (ISSS). Even when the effects of gender and grade level were controlled for, the results from regression analyses revealed that greater interpersonal independence, interpersonal initiative, interpersonal responsibility, and interpersonal openness are associated with lesser PTSD symptoms 16 months later.
Long‐term population dynamics of a managed burrowing owl colony
Authors: Barclay John H. , Korfanta Nicole M. , Kauffman Matthew J. 
Published: July 2011

AbstractWe analyzed the population dynamics of a burrowing owl (Athene cunicularia) colony at Mineta San Jose International Airport in San Jose, California, USA from 1990–2007. This colony was managed by using artificial burrows to reduce the occurrence of nesting owls along runways and within major airport improvement projects during the study period. We estimated annual reproduction in natural and artificial burrows and age‐specific survival rates with mark–recapture techniques, and we estimated the relative contribution of these vital rates to population dynamics using a life table response experiment. The breeding colony showed 2 distinct periods of change: high population growth from 7 nesting pairs in 1991 to 40 pairs in 2002 and population decline to 17 pairs in 2007. Reproduction was highly variable: annual nesting success (pairs that raised ≥1 young) averaged 79% and ranged from 36% to 100%, whereas fecundity averaged 3.36 juveniles/pair and ranged from 1.43 juveniles/pair to 4.54 juveniles/pair. We estimated annual adult survival at 0.710 during the period of colony increase from 1996 to 2001 and 0.465 during decline from 2002 to 2007, but there was no change in annual survival of juveniles between the 2 time periods. Long‐term population growth rate (λ) estimated from average vital rates wasλa = 1.072 withλi = 1.288 during colony increase andλd = 0.921 (Δλ = 0.368) during decline. A life table response experiment showed that change in adult survival rate during increasing and declining phases explained more than twice the variation in growth rate than other vital rates. Our findings suggest that management and conservation of declining burrowing owl populations should address factors that influence adult survival. © 2011 The Wildlife Society.
Energetics of surface‐active terrestrial salamanders in experimentally harvested forest
Authors: Homyack Jessica A. , Haas Carola A. , Hopkins William A. 
Published: July 2011

AbstractEnvironmental temperatures affect nearly all aspects of ectotherm physiology, including terrestrial salamanders. Therefore, habitat disturbances that alter temperature regimes may interact with physiological processes to affect energy budgets of salamanders or constrain surface activity and possibly lead to changes in population‐level parameters. We hypothesized that warmer surface temperatures following harvesting of canopy trees could cause surface‐active salamanders to expend more energy for metabolism, potentially leaving a smaller proportion of the energy budget available for reproduction or storage. From 2006 to 2008, we quantified temperature regimes of salamander refugia in a field experiment replicated at 4 sites that included plots subjected to a timber harvest and plots not manipulated during this time period. At each site, we quantified temperature regimes in regenerating forest stands which, approximately 10 years earlier, experienced a range of harvest intensity from shelterwood to silvicultural clearcut. Further, we compared energetic parameters including 1) calories required to maintain homeostasis across an active season, 2) abundance of available potential energy (i.e., invertebrate prey), and 3) a measure of growth and storage (i.e., body condition index) among silvicultural treatments for surface‐active salamanders. For surface‐active eastern red‐backed salamanders (Plethodon cinereus), mean calories required for maintenance were approximately 33% greater in recently harvested forest compared to unharvested controls, but body condition was inconsistent among treatments, and invertebrate abundances were similar among treatments but differed by study site. In contrast, we did not detect a treatment effect in any energetic metric 8–14 growing seasons after harvesting. Given that surface‐active salamanders in recently harvested forest may be forced to restrain behaviors associated with foraging and mating or trade‐off growth or reproduction for increased basic maintenance costs, energetics may be an important but overlooked short‐term contributor to observed changes in abundances, reproductive demography, or surface activities after timber harvesting. Managing for both the rapid recovery of understory vegetation and retention of large stumps and logs may help mitigate warming of microclimate for salamanders and should be considered further. © The Wildlife Society, 2011
Photocathodic protection properties of NiP/TiO2 bilayer coatings by a combined electroless plating and sol–gel method
Authors: Zhou M.‐J. , Zhang N. , Zhang L. , Yan J.‐H. 
Published: July 2011

AbstractA combined electroless plating and sol–gel method was developed for preparing a NiP/TiO2 bilayer coating to achieve an especial photocathodic protection effect for A3 low carbon steel. Photocathodic protection properties of the coating were investigated by the electrochemical method. Surface morphology and structure of the coating were characterized by scanning electron microscope (SEM) and X‐ray diffraction (XRD). The results show that the open circuit potential (OCP) of the NiP/TiO2 coating electrode shifts to −0.42 V under UV irradiation, which is lower than the corrosion potential of A3 low carbon steel. When the light is turned off, the photocathodic protection effect cannot be maintained. In addition, the mechanism of photocathodic protection for the coating was also explored.
Inhibition investigation and determination of some quantum chemical parameters of 1‐(4‐(dimethylamino)benzylidene)thiosemicarbazide on steel alloys in sulfuric acid medium
Authors: Hosseini S. M. A. , Bahrami M. J. , Dorehgiraee A. 
Published: July 2011

AbstractThe inhibition effect of 1‐(4‐(dimethylamino)benzylidene)thiosemicarbazide (DBT) on the corrosion behavior of 304 stainless steel and mild steel in 0.5 M sulfuric acid solution was investigated using weight loss and potentiostatic polarization methods. The experimental results suggest that DBT inhibits the corrosion of the steels in acid solution. The inhibition efficiencies increased as the concentration of the compound was increased. The calculated inhibition efficiencies from the two investigated methods were in good agreement. Potentiostatic polarization measurements indicate that DBT acts as a mixed type inhibitor for both alloys. The adsorption of inhibitor on the steel surfaces obeys Langmuir adsorption isotherm. The structure of DBT was optimized using PM3 semi‐empirical method. Highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy levels, ELUMO − EHOMO (energy gap), dipole moment (µ), and Mulliken charge densities for this molecule were computed and the adsorption mechanism was discussed. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the surfaces of the alloys.
Characterization of hydrogen charging of 2205 duplex stainless steel and its correlation with hydrogen‐induced cracking
Authors: Luo H. , Dong C. F. , Liu Z. Y. , Maha M. T. J. , Li X. G. 
Published: July 2011

AbstractThe effect of various experimental conditions (i.e., hydrogen charging current density, charging time, solution concentration, and temperature) on the embrittlement and cracking susceptibility of 2205 duplex stainless steel was studied by electrochemical hydrogen charging and slow strain rate tests. The results showed that the choice of the experimental conditions had obvious effect on the hydrogen concentration in the specimens. A relationship between the embrittlement and hydrogen charging conditions was established by the investigation of the fracture morphology. Under the free‐charging condition, the fracture surfaces were characteristic of dimples, while on the condition of the dynamic hydrogen charging, the hydrogen‐induced fracture showed the appearance of cleavage. Further examination of fracture cracks confirmed that the ferrite phase acts as a preferential path for crack propagation.
Detection and characterisation of intergranular stress‐corrosion cracking on austenitic stainless steel
Authors: Kovač J. , Marrow T. J. , Govekar E. , Legat A. 
Published: July 2011

AbstractIntergranular stress‐corrosion cracking (IGSCC) on a sensitised type AISI 304 stainless steel specimen was monitored simultaneously by acoustic emission, electrochemical noise, elongation measurements and a digital imaging system. The specimen was exposed to an aqueous sodium thiosulphate solution in combination with a constant load. It was established that before the final fracture two large cracks and numerous smaller cracks had developed. Detection and characterisation of the stress‐corrosion processes which generated these cracks are discussed. The results confirm and generalise previously established correlations between various parameters obtained by the implemented characterisation methods and IGSCC processes. Additionally, a clear differentiation between crack related and crack non‐related AE signals was made based on an analysis of the AE signals. The relationship between the crack lengths calculated by means of digital image correlation analysis and the electrochemical current noise was also established.
Failure analysis of leakage on titanium tubes within heat exchangers in a nuclear power plant. Part II: Mechanical degradation
Authors: Gong Y. , Yang Z.‐G. , Yuan J.‐Z. 
Published: July 2011

AbstractSerious failure incidents like clogging, quick thinning, and leakage frequently occurred on lots of titanium tubes of heat exchangers in a nuclear power plant in China. In the Part I of the whole failure analysis study with totally two parts, factors mainly involving three kinds of electrochemical corrosions were investigated, including galvanic corrosion, crevice corrosion, and hydrogen‐assisted corrosion. In the current Part II, through microscopically analyzing the ruptures on the leaked tubes by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), another four causes dominantly lying in the aspect of mechanical degradation were determined – clogging, erosion, mechanical damaging, and fretting. Among them, the erosion effect was the primary one, thus the stresses it exerted on the tube wall were also supplementarily evaluated by finite element method (FEM). Based on the analysis results, the different degradation extents and morphologies by erosion on the tubes when they were clogged by different substances such as seashell, rubber debris, and sediments were compared, and relevant mechanisms were discussed. Finally, countermeasures were put forward as well.
Helical Nanoribbons Fabricated by Electrospinning
Authors: Chang Guoqing , Shen Jianyi 
Published: July 2011

AbstractA fabrication setup was specially designed so that one stream of sol of polyvinyl pyrrolidone (PVP), electrospun to form a bundle of fibers, acted as an axis between two rotating needles, and a second stream of PVP sol containing copper nitrate was electrospun around the fiber bundle axis to form a coil. This was turned into a coiled ribbon upon treatment in moisture. After calcination and reduction, a helical microcoil of nanocopper ribbon was produced, with controlled diameter and pitch. The width and thickness of the ribbon could be varied by manipulating the diameter of the coiled fiber and its treatment time in moisture.magnified image
Synthesis of Nanosized (<20 nm) Polymer Particles by Radical Polymerization in Miniemulsion Employing in situ Surfactant Formation
Authors: Guo Yi , Zetterlund Per B. 
Published: July 2011

AbstractA novel method for synthesis of ultrafine polymeric nanoparticles of diameters less than 20 nm has been developed. The method is based on miniemulsion polymerization exploiting combination of the in situ surfactant generation approach (whereby the surfactant is formed at the oil–water interface by reaction between an organic acid and a base) and ultrasonication. Conventional radical polymerization and nitroxide‐mediated radical polymerization of styrene have been conducted in miniemulsion using oleic acid/potassium hydroxide, demonstrating that particles with diameters less than 20 nm can be obtained by this approach at surfactant contents much lower than traditionally required in microemulsion polymerizations.magnified image
Mechanical properties of the AlSi1MgMn aluminium alloy (AA6082) processed by gradation rolling
Authors: Neugebauer R. , Sterzing A. , Bergmann M. 
Published: July 2011

AbstractAn outstanding approach for the tailoring of material properties is the grain refinement by the application of very high strains with changing strain path. Methods of severe plastic deformation (SPD) can create ultrafine‐grained or nanostructured metallic materials with new combinations of physical and mechanical properties. Classical severe plastic deformation methods focus typically on the uniform modification of the microstructure throughout the complete volume. In the present study the processing and subsequent characterisation of an age hardenable aluminium alloy subjected to a partial severe plastic deformation is presented. The new technology, referred to as gradation rolling, is applied for the efficient manufacturing of rod shaped parts with locally different grain sizes. After the presentation of the process principle [1], the characterization of the microstructure [2] and the identification of deformation routes during processing [3] the first mechanical characterization of a wrought aluminium alloy is presented. The resulting mechanical properties in different regions of a graded material are analyzed by hardness measurements and tensile tests. The mechanical properties of the graded billets show the typical characteristics of coarse grained material in the core region and that of severely deformed material in the kneaded region at the surface of the billets.
Influence of strain gradients on the grain refinement during industrial scale ECAP
Authors: Frint P. , Hockauf M. , Dietrich D. , Halle T. , Wagner M. F.‐X. , Lampke T. 
Published: July 2011

AbstractThe microstructure of the aluminium alloy 6060 after industrial scale (cross‐section 50×50 mm2) equal‐channel angular pressing (ECAP) is studied. We focus on processing without additional backpressure in order to allow the formation of a corner gap and the corresponding development of a distinct strain gradient after one pass. Low voltage scanning transmission electron microscopy (STEM) and electron backscatter diffraction analysis (EBSD) are used to determine the average grain size, grain boundary misorientation angles and grain shape aspect ratios. These microstructural parameters are analysed for three characteristic locations from top to bottom within the billet. Our EBSD observations clearly document the occurrence of global strain gradients and microstructural heterogeneity. The STEM analyses expand the information on this heterogeneous deformation for the investigated locations in the sub‐micrometer range. In good agreement with previous studies, our results provide detailed information on how a heterogeneous induced shear strain affects microstructure and mechanical properties when ECAP is performed without backpressure.
Selective J‐resolved‐HMQC‐1 and ‐2, new methods for measuring proton–proton coupling constants in strongly coupled spin systems
Authors: Furihata Kazuo , Tashiro Mitsuru 
Published: July 2011

AbstractEfficient pulse sequences for measuring 1H–1H coupling constants (JHH) in strongly coupled spin systems, named selective J‐resolved‐HMQC‐1 and ‐2, have been developed. In the strongly coupled spin systems such as ‐CH2‐CHA(OH)‐CHB(OH)‐CH2‐, measurements of 3JHAHB are generally difficult owing to the complicated splitting caused by the adjacent CH2 protons. For easier and accurate measurements of 3JHAHB in such a spin system, a selective excitation pulse is incorporated into the J‐resolved HMQC pulse sequence. In the proposed methods, only two strongly coupled protons, HA and HB which are excited by a selective pulse, are observed as J‐resolved HMQC signals. The cross peaks of HA and HB appear as doublets owing to 3JHAHB along the F1 dimension in the selective J‐resolved HMQC‐1 and ‐2 experiments. The efficiency of the proposed pulse sequences has been demonstrated in application to the stereochemical studies of the complicated natural product, monazomycin. Copyright © 2011 John Wiley & Sons, Ltd.
Measurement of long‐range proton–carbon coupling constants from pure in‐phase 1D multiplets
Authors: Espinosa Juan F. , Vidal Paloma , Parella Teodor , Gil Sergi 
Published: July 2011

AbstractThe SELective INverse detection of carbon–proton CORrelation pulse sequence that yields a 1D spectrum of a proton directly bonded to a selected carbon resonance has been converted into a proton and carbon double‐selective variant that provides a 1H spectrum of a selected proton that is long‐range coupled to a specific carbon resonance. The resulting 1D proton multiplet exhibits a pure absorptive in‐phase lineshape for precise measurement of specific long‐range proton–carbon coupling constants in small organic molecules at natural abundance. Copyright © 2011 John Wiley & Sons, Ltd.