Minimal wave speed of a competition integrodifference system

In this paper, we study the minimal wave speed of a competitive system. By constructing upper and lower solutions, we confirm the existence of travelling wave solution at the critical wave speed. This completes earlier results found in the literature. Our conclusion implies that the asymptotic decay behaviour of solutions at the critical wave speed is different from that of solutions at larger wave speeds.     

四阶奇异边值问题正解的全局结构

利用上下解方法研究了一类四阶奇异边值问题正解的全局结构.证明了解集存在无界连通分支并给出了多个正解的存在性结果,推广和改进了相关文献的结果.     

锂离子注入对V2O5薄膜光吸收的影响

采用真空蒸发经热处理制备了Ｖ２Ｏ５薄膜,使用二电极恒流法从１Ｍ／ＬＬｉＣｌＯ４的ＰＣ电解质溶液向Ｖ２Ｏ５薄膜注入锂离子,形成ＬｉｘＶ２Ｏ５（０≤ｘ≤０．５４）,测量了Ｖ２Ｏ５薄膜近垂直反射和透射光谱,计算了光吸收系数。Ｘ射线衍射分析表明薄膜为微晶结构。吸收系数与光子能量关系曲线中存在两个不同的变化区域,光子能量较高部分,（αｈν）１２与ｈν有线性关系;较低部分,吸收光谱存在一个尾巴。这两个区域的分界能量取决于电子和锂离子的注入量。研究结果表明Ｖ２Ｏ５薄膜阳极电致变色起源于吸收边缘的移动,而阴极电致变色则来源于小极化子的吸收     

跨温区互联技术

以半导体材料为基础的微电子技术正面临尺寸极限和功耗的双重挑战与发展瓶颈. 低温电子学作为突破上述瓶颈的新兴应用研究学科之一, 得到科研和产业界越来越多的关注.2017 年起, 低温电子学和量子信息处理被国际器件与系统路线图(IRDS) 列为重点关注的十大焦点领域之一. 以低温到室温的微弱、 高频电信号传输为核心的跨温区互联技术是低温电子学和量子信息处理必须解决的关键技术之一. 本文对跨温区互联面临的主要问题与挑战、 目前的进展和未来展望进行了综述, 为我国开展相关研究工作提供参考.     

气相色谱-质谱法测定食品中的甲醛

建立了用气相色谱-质谱-选择离子检测(GC-MS-SIM)测定食品中甲醛和次硫酸氢钠甲醛的新方法。改进了样品提取方法,考察了样品提取时间及衍生条件等因素的影响,确定最佳提取条件为超声波振荡4JDmin,衍生条件为2g／L的2,4-二硝基苯肼(DNPH)作衍生剂避光反应6h;采用选择离子m／z79和m／z210进行GC-MS检测。结果表明,本法可消除复杂基体的干扰,简便快速,准确可靠,灵敏度高,相对标准偏差小于7％;回收率在88．4％～93．8％;检出限为0．1mg／kg。该方法已应用于面粉、面条、啤酒、饮料等各类食品中甲醛和次硫酸氢钠甲醛的测定。     

Ir-Doped CuPd Single-Crystalline Mesoporous Nanotetrahedrons for Ethylene Glycol Oxidation Electrocatalysis: Enhanced Selective Cleavage of C−C Bond

The development of highly efficient electrocatalysts for complete oxidation of ethylene glycol (EG) in direct EG fuel cells is of decisive importance to hold higher energy efficiency. Despite some achievements, their progress, especially electrocatalytic selectivity to complete oxidated C₁ products, is remarkably slower than expected. In this work, we developed a facile aqueous synthesis of Ir-doped CuPd single-crystalline mesoporous nanotetrahedrons (Ir-CuPd SMTs) as high-performance electrocatalyst for promoting oxidation cleavage of C−C bond in alkaline EG oxidation reaction (EGOR) electrocatalysis. The synthesis relied on precise reduction/co-nucleation and epitaxial growth of Ir, Cu and Pd precursors with cetyltrimethylammonium chloride as the mesopore-forming surfactant and extra Br⁻ as the facet-selective agent under ambient conditions. The products featured concave nanotetrahedron morphology enclosed by well-defined (111) facets, single-crystalline and mesoporous structure radiated from the center, and uniform elemental composition without any phase separation. Ir-CuPd SMTs disclosed remarkably enhanced electrocatalytic activity and excellent stability as well as superior selectivity of C₁ products for alkaline EGOR electrocatalysis. Detailed mechanism studies demonstrated that performance improvement came from structural and compositional synergies, which kinetically accelerated transports of electrons/reactants within active sites of penetrated mesopores and facilitated oxidation cleavage of high-energy-barrier C−C bond of EG for desired C₁ products. More interestingly, Ir-CuPd SMTs performed well in coupled electrocatalysis of anode EGOR and cathode nitrate reduction, highlighting its high potential as bifunctional electrocatalyst in various applications.     

The Superposition of Coherent States Along a Straight Line with Thermal Noise

ＴｈｅＳｕｐｅｒｐｏｓｉｔｉｏｎｏｆＣｏｈｅｒｅｎｔＳｔａｔｅｓＡｌｏｎｇａＳｔｒａｉｇｈｔＬｉｎｅｗｉｔｈＴｈｅｒｍａｌＮｏｉｓｅ￥ＺＨＵＫａｉｃｈｅｎｇ；ＭＡＳｏｎｇｔｉｎｇ；ＴＡＮＧＨｕｉｑｉｎ；ＨＵＡＮＧＤｕｚｈｉ；ＬＩＸｉｎｇｕａｎｇ（Ｄｅ...     

Beam Propagation Factor and Generation of Cosh-squared-Gaussian Beams

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｒｅｃｅｎｔｌｙ ,Ｃａｓｐｅｒｓｏｎ ｅｔａｌ.[1,2 ]ｒｅｐｒｅｓｅｎｔｅｄａｓｏ ｃａｌｌｅｄＨｅｒｍｉｔｅ ｓｉｎｕｓｏｉｄａｌ Ｇａｕｓｓｉａｎｂｅａｍｓ (ＨＳＧＢｓ)ａｎｄ ｐｒｏｖｅｄｔｈａｔｔｈｅｙａｒｅｓｔｉｌｌｓｏｌｕｔｉｏｎｓｏｆｔｈｅｗａｖｅｅｑｕａｔｉｏｎｕｎｄｅｒｔｈｅ ｐａｒａｘｉａｌａｐｐｒｏｘｉｍａｔｉｏｎａｎｄｔｈｅｉｒｃｏｍｐｌｅｘｒａｄｉｕｓｏｆｃｕｒｖａｔｕｒｅａｎｄｍｅａｎｒａｙｐａｒａｍｅｔｅｒｓｏｂｅｙｔｈｅｗｅｌｌ ｋｎｏｗｎＡ…     

Characterization of a Series of Far Red Absorbing Perylene Diones: A New Class of Fluorescent Probes for Biological Applications

The far red region of the spectrum is increasingly being utilised in many applications in the biosciences. However, apart from the cyanine group of dyes, there are relatively few far red fluorescent probes available which are of practical use. We have synthesised and characterised a new class of far red fluorescent probes based on the perylene dione chromophore. The 2,10 di-substituted perylene diones possess broad absorption spectra (>90 nm bandwidths), large Stokes shifts (>60 nm) and quantum yields of up to 0.5 with a maximum absorption at 610–640 nm in organic solvents or in solutions of non-ionic detergents. A number of derivatives have been synthesised that can be used as membrane probes, as chromogenic substrates for alkaline phosphatase, and for the labelling of macromolecules such as proteins and DNA. These novel far red fluorophores have potential applications in diagnostic and research applications.     

ELEMENTARY BIFURCATIONS FOR A SIMPLE DYNAMICAL SYSTEM UNDER NON-GAUSSIAN LEVY NOISES

Nonlinear dynamical systems are sometimes under the influence of random fluctuations. It is desirable to examine possible bifurcations for stochastic dynamical systems when a parameter varies. A computational analysis is conducted to investigate bifurcations of a simple dynamical system under non-Gaussian α-stable Lévy motions, by examining the changes in stationary probability density functions for the solution orbits of this stochastic system. The stationary probability density functions are obtained by solving a nonlocal Fokker-Planck equation numerically. This allows numerically investigating phenomenological bifurcation, or P-bifurcation, for stochastic differential equations with non-Gaussian Lévy noises.