Atomic Insights into the Enhanced Surface Stability in High Voltage Cathode Materials by Ultrathin Coating

Surface properties of electrode materials play a critical role in the function of batteries. Therefore, surface modifications, such as coatings, have been widely used to improve battery performance. Understanding how these coatings function to improve battery performance is crucial for both scientific research and applications. In this study the electrochemical performance of coated and uncoated LiNi_0.5Mn_1.5O₄ (LNMO) electrodes is correlated with ensemble‐averaged soft X‐ray absorption spectroscopy (XAS) and spatially resolved scanning transmission electron microscopy‐electron energy loss spectroscopy (STEM‐EELS) to illustrate the mechanism of how ultrathin layer Al₂O₃ coatings improve the cycle life of LiNi_0.5Mn_1.5O₄. Mn²⁺ evolution on the surface is clearly observed in the uncoated sample, which results from the reaction between the electrolytic solution and the surfaces of LiNi_0.5Mn_1.5O₄ particles, and also possibly atomic structure reconstructions and oxygen loss from the surface region in LiNi_0.5Mn_1.5O₄. The coating effectively suppresses Mn²⁺ evolution and improves the battery performance by decelerating the impedance buildup from the surface passivation. This study demonstrates the importance of combining ensemble‐averaged techniques (e.g., XAS) with localized techniques (e.g., STEM‐EELS), as the latter may yield unrepresentative information due to the limited number of studied particles, and sheds light on the design of future coating processes and materials.     

具有壁面Weis-Fogh机构流体动力多重网格并行计算

应用多重网格区域分裂并行计算方法研究具有壁面Weis-Fogh机构绕流，将二维物理平面流动区域变换为矩形区域，推导出流函数的多重网格差分计算格式，编制出并行计算程序。全部计算在英国London大学ITL并行计算中心完成。结果表明，多重网格并行计算具有较高的加速比，绕机翼的环量计算值与理论吻合。     

Battlemind debriefing and battlemind training as early interventions with soldiers returning from iraq: Randomization by platoon.

Researchers have found that there is an increase in mental heath problems as a result of military-related traumatic events, and such problems increase in the months following return from combat. Nevertheless, researchers have not assessed the impact of early intervention efforts with this at-risk population. In the present study, the authors compared different early interventions with 2,297 U.S. soldiers following a year-long deployment to Iraq. Platoons were randomly assigned to standard postdeployment stress education, Battlemind debriefing, and small and large group Battlemind training. Results from a 4-month follow-up with 1,060 participants showed those with high levels of combat exposure who received Battlemind debriefing reported fewer posttraumatic stress symptoms, depression symptoms, and sleep problems than those in stress education. Small group Battlemind training participants with high combat exposure reported fewer posttraumatic stress symptoms and sleep problems than stress education participants. Compared to stress education participants, large group Battlemind training participants with high combat exposure reported fewer posttraumatic stress symptoms and lower levels of stigma and, regardless of combat exposure, reported fewer depression symptoms. Findings demonstrate that brief early interventions have the potential to be effective with at-risk occupational groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxalylhydrazinium Nitrate and Dinitrate—Efficiency Meets Performance

Oxalylhydrazinium nitrate (OHN) and dinitrate (OHDN) were synthesized by protonation of oxalyldihydrazide with nitric acid. The synthesis is extremely cost effective (～$40/kg at the lab scale) and can be carried out in large scales and very good yields. OHN and OHDN were intensively characterized by low-temperature X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and vibrational spectroscopy. These new organic nitrate salts could be used as powerful ingredients in energetic formulations due to their low sensitivities (measured by Bundesanstalt für Materialforschung und Pröfung methods). Their thermal stability was investigated by differential scanning calorimetry (DSC) measurements. Further thermal studies of OHN showed compatibility with TNT (2,4,6-trinitrotoluene), DNAN (2,4-dinitroanisole), and RDX (1,3,5-trinitro-1,3,5-triazinane). The theoretical detonation and propulsion parameters of OHN and OHDN were calculated with the EXPLO5.5 code and compared to well-known insensitive explosives. The aquatic toxicity of OHN was determined by the luminescent bacteria inhibition test, yielding a much lower toxicity than RDX.     

Enhanced maternal aggression and associated changes in neuropeptide gene expression in multiparous rats.

Although it has often been speculated that prior reproductive experience improves subsequent maternal care, few studies have examined specific changes in behavior during a 1st versus 2nd lactation. During lactation, mothers display heightened aggression toward male intruders, purportedly to protect vulnerable young. In the current study, maternal aggression was examined in primiparous and age-matched multiparous females on postpartum days 5 (PPD5) and PPD15. Expression of oxytocin, oxytocin receptor, arginine vasopressin, arginine vasopressin V1a receptors, and corticotrophin-releasing hormone mRNA was measured following aggression testing at both time points using real-time quantitative PCR in brain regions previously implicated in the regulation of maternal aggression. Multiparity significantly enhanced maternal aggression on PPD5 but not on PPD15. In addition, this increased aggression was associated with region- and gene-specific changes in mRNA expression. These findings indicate that reproductive experience enhances maternal aggression, an effect that may be mediated by region-specific alterations in neuropeptidergic activity. The adaptations observed in multiparous females provide an innate model for the study of neuroplasticity in the regulation of aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Precise slicing of concurrent programs

While there exist efficient algorithms to slice sequential programs precisely, there are only two algorithms for precise slicing of concurrent interprocedural programs with recursive procedures (Krinke in Proc. ESEC/FSE’03, pp. 178–187, 2003; Nanda and Ramesh in ACM Toplas. 28(6):1088–1144, 2006). We present an empirical evaluation of both algorithms for Java. We demonstrate that both algorithms provide the same precision up to the model of concurrency in use and show that the concurrency model has strong impact on slice precision and computation costs. Furthermore, we extend both algorithms to support dynamic thread creation both in loops and recursion—a feature that the original algorithms could not fully handle. The worst case complexity of the algorithms being exponential, we developed several optimizations and compared these with each other and with algorithms that trade precision for speed. Finally, we show that one algorithm may produce incorrect slices and present a remedy.     

Reoptimization of the Shortest Common Superstring Problem

A reoptimization problem describes the following scenario: given an instance of an optimization problem together with an optimal solution for it, we want to find a good solution for a locally modified instance.     

Adiabatic shear failure in brittle solids

Recent studies have revealed microscopic amorphous lamella resulting from inelastic deformation in the ballistic impact of boron carbide ceramic. The possibility that these deformation features are a consequence of adiabatic shear deformation in the impact event is explored. An early theory of adiabatic shear that was limited to the response of rigid-plastic deformation is expanded to include elastic strain energy. The study reveals that elastic strain energy is commonly a small, but not negligible, contribution to impact-induced adiabatic shear in metals. Elastic strain energy is paramount in brittle solids. Relations are developed from the theory to predict the nominal width and spacing of adiabatic shear-bands in brittle solids. Comparisons of the theoretical predictions are consistent with observations of impact-induced deformation features in boron carbide.     

LIQUID PHASE CO-OXIDATION OF THIOPHENOL AND STYRENE BY OXYGEN AND t-BUTYL HYDROPEROXIDE

ABSTRACT

Instability problems in both shale and petroleum derived middle distillate jet fuels have been correlated with the presence of peroxidic species. Although a good body of knowledge exists concerning the formation of peroxides in the liquid phase, relatively little is known about the reaction/ decomposition pathways available when other functional groups are present, since sulfur is the most abundant heteroatam present in jet fuels, the reaction of t-butyl hydroperoxide (tBKP) and/or oxygen with thiophenol in the presence of the active olefin, styrene, was examined in deaerated benzene at 120°C. The complex product mixture was analyzed by combined capillary column GC/MS. Major products included acetone, t-butanol and isdbutylene from the tBHP. Thiophenol and styrene combined to form addition products. Phenyl disulfide was observed from the thiophenol. The results indicated that although the product slate was complex, it was possible to explain the product mix in terms of a few competing reactions.