Nonisothermal kinetics study with advanced isoconversional procedure and DAEM

The precursor of LiNiPO₄ was synthesized by solid-state reaction at low-heating temperature using LiOH·H₂O and NH₄NiPO₄·H₂O as raw materials. LiNiPO₄ was obtained by calcining the precursor. Based on the advanced isoconversional procedure and the distributed activation energy model (DAEM), the activation energies calculated indicated that the thermal process involved two stages which stage II was a kinetically complex process, but stage I was single-step process. The most probable mechanism for the stage I is random nucleation and subsequent growth. DAEM and nonlinear model-fitting method were applied to study the stage II of decomposition process of the precursor. The distributions of activation energy, f(E _a) and values of preexponential factor A of the stage II of the thermal decomposition of precursor were obtained on the basis of DAEM. The results of nonlinear model-fitting method showed the most probable mechanisms of the parallel reactions for stage II are chemical reaction and nucleation.     

An Antibody with a Variable‐Region Coiled‐Coil “Knob” Domain

The X‐ray crystal structure of a bovine antibody (BLV1H12) revealed a unique structure in its ultralong heavy chain complementarity determining region 3 (CDR3H) that folds into a solvent‐exposed β‐strand “stalk” fused to a disulfide crosslinked “knob” domain. We have substituted an antiparallel heterodimeric coiled‐coil motif for the β‐strand stalk in this antibody. The resulting antibody (Ab‐coil) expresses in mammalian cells and has a stability similar to that of the parent bovine antibody. MS analysis of H–D exchange supports the coiled‐coil structure of the substituted peptides. Substitution of the knob‐domain of Ab‐coil with bovine granulocyte colony‐stimulating factor (bGCSF) results in a stably expressed chimeric antibody, which proliferates mouse NFS‐60 cells with a potency comparable to that of bGCSF. This work demonstrates the utility of this novel coiled‐coil CDR3 motif as a means for generating stable, potent antibody fusion proteins with useful pharmacological properties.     

N‐Heterocyclic Carbene,High Oxidation State Molybdenum Alkylidene Complexes: Functional‐Group‐Tolerant Cationic Metathesis Catalysts

We synthesized the first N‐heterocyclic carbene (NHC) complexes of Schrock’s molybdenum imido alkylidene bis(triflate) complexes. Unlike existing bis(triflate) complexes, the novel 16‐electron complexes represent metathesis active, functional‐group‐tolerant catalysts. Single‐crystal X‐ray structures of two representatives of this novel class of Schrock catalysts are presented and reactivity is discussed in view of their structural peculiarities. In the presence of monomer (substrate), these catalysts form cationic species and can be employed in ring‐closing metathesis (RCM), ring‐opening metathesis polymerization (ROMP), as well as in the cyclopolymerization of α,ω‐diynes. Monomers containing functional groups, which are not tolerated by the existing variations of Schrock’s catalyst, e.g., sec‐amine, hydroxy, and carboxylic acid moieties, can be used. These catalysts therefore hold great promise in both organic and polymer chemistry, where they allow for the use of protic monomers.     

高碳铬铁在氢氧化钠水溶液中电化学氧化过程

铬铁电化学氧化法是一种新的制备铬酸钠的方法,然而高碳铬铁在NaOH水溶液中的电化学氧化过程尚不明确。 采用循环伏安法(CV)、稳态极化法(LSV)等电化学测试方法对金属铬、高碳铬铁在NaOH水溶液中的电化学氧化过程进行研究,通过扫描电子显微镜(SEM)、能量散射谱(EDS)和X射线光电子能谱(XPS)对高碳铬铁电解后固相产物表征,判断固相产物的组成。 结果表明,高碳铬铁不同于金属铬的电氧化过程,它在NaOH溶液中通过Cr(0)→Cr(Ⅵ)的电氧化方式生成铬酸钠,中间产物Cr(OH)₃和Fe(0)发生电化学反应生成稳定的FeCr₂O₄。 随着NaOH浓度的增加,电势较低时,受高碳铬铁中Fe(0)的影响,高碳铬铁容易在NaOH水溶液中发生钝化;当电势足够正时,钝化膜溶解,生成铬酸钠、氢氧化铁和亚铬酸亚铁,同时,阳极表面有氧气析出。 高碳铬铁电化学氧化制备铬酸钠的适宜条件:碱浓度≥2 mol/L,阳极电势≥1.6 V(vs.SCE)。     

Dehydration of glycerol with silica–phosphate-supported copper catalyst

Research on Chemical Intermediates - Silica–phosphate-supported copper catalyst was prepared by neutralization of sodium silicate with orthophosphoric acid followed by the addition of copper...     

Building an Air Stable and Lithium Deposition Regulable Garnet Interface from Moderate‐Temperature Conversion Chemistry

Garnet‐type electrolytes suffer from unstable chemistry against air exposure, which generates contaminants on electrolyte surface and accounts for poor interfacial contact with the Li metal. Thermal treatment of the garnet at >700 °C could remove the surface contaminants, yet it regenerates the contaminants in the air, and aggravates the Li dendrite issue as more electron‐conducting defective sites are exposed. In a departure from the removal approach, here we report a new surface chemistry that converts the contaminants into a fluorinated interface at moderate temperature <180 °C. The modified interface shows a high electron tunneling barrier and a low energy barrier for Li⁺ surface diffusion, so that it enables dendrite‐proof Li plating/stripping at a high critical current density of 1.4 mA cm^?2. Moreover, the modified interface exhibits high chemical and electrochemical stability against air exposure, which prevents regeneration of contaminants and keeps high critical current density of 1.1 mA cm^?2. The new chemistry presents a practical solution for realization of high‐energy solid‐state Li metal batteries.     

Stimuli‐Responsive Naphthalene Diimide as Invisible Ink: A Rewritable Fluorescent Platform for Anti‐Counterfeiting

Herein, we report an approach to combat counterfeiting and storage of valuable information based on the solid‐state fluorescence switching behavior of isoniazid functionalized naphthalene diimide (ISO_NDI) in response to an external stimuli (i. e., HCl vapor). The unique feature of ISO_NDI is further utilized to develop an invisible ink (ISO_NDI‐PVA) with commercial polymer polyvinyl alcohol (PVA). A solid‐state fluorescence recovery was observed while loading with HCl vapors. This exclusive property of the material could be applied directly as a security ink for confidential data storage purpose. Based on above strategy, we successfully realized the rewritable application by using ISO_NDI‐PVA ink and confirm its practical efficacy on various substrates by creating different patterns. The solid‐state fluorescence switching behavior of ISO_NDI‐PVA ink exhibited reversible on/off signal for multiple cycles under the influence of HCl/NH₃ vapors. Mechanistic investigation supports a clear participation of intermolecular charge transfer (ICT) phenomenon in the solid‐state fluorescence switching property. The ease of fabricating the ink with invisible to visible characteristics in response to HCl vapors provides new opportunities for exploring the application of ISO_NDI‐PVA as invisible ink for targeted security applications.     

New characterizations of digraphs represented by intervals

We present new characterizations of interval digraphs, interval graphs, and indifference digraphs, using linear orderings of edges and vertices. © 1996 John Wiley & Sons, Inc.     

基于特征圆单目视觉的飞机舵面角位移标定技术

提出了一种基于特征圆单目视觉的非接触式飞机舵面角位移标定技术。用一台数码摄像机对固定在飞机舵面上的特征圆进行拍照,经数字图像处理后确定五个特征点的坐标,利用针孔成像和射影变换原理建立物像空间坐标解算模型,计算出特征圆的法线相对方向和圆心的相对位置,舵面角位移由该圆的法线方向确定。仿真结果表明,该方法具有标定过程简单、实时、快速和准确的特点,标定精度可达到0.1°。该技术也可用于航天器上实时测量交会对接时的相对位姿参数。     

Analysis and optimisation of grooved parallel slider bearings with cavitation

Meccanica - This paper introduces an analytical approach to optimize the textured bearing with cavitation to improve the load support. For this purpose, a grooved parallel slider bearing is...