Nonclassical Crystallization and Size Control of Ultra‐Small MoO2 Nanoparticles in Water

Size tuning for MoO₂ nanoparticles is demonstrated for the first time over a wide range 2–100 nm, through a colloidal route into water. A nucleation‐growth mechanism based on oriented attachment is evidenced to rationalize the impact of two simple synthetic levers: reactant ratio and temperature. The smallest non‐aggregated crystalline MoO₂ nanoparticles are reported, with specific surface area reaching 86 m² g^?1. Size and morphology control, along with the ability to produce, non‐aggregated ultra‐small MoO₂ particles are important for a wide range of applications, such as catalysis and energy storage. To exemplify the importance of size tuning, the impact of downscaling on the electrochemical properties in Li‐ion batteries is investigated.     

Relations between the Local Chromatic Number and Its Directed Version

The local chromatic number is a coloring parameter defined as the minimum number of colors that should appear in the most colorful closed neighborhood of a vertex under any proper coloring of the graph. Its directed version is the same when we consider only outneighborhoods in a directed graph. For digraphs with all arcs being present in both directions the two values are obviously equal. Here, we consider oriented graphs. We show the existence of a graph where the directed local chromatic number of all oriented versions of the graph is strictly less than the local chromatic number of the underlying undirected graph. We show that for fractional versions the analogous problem has a different answer: there always exists an orientation for which the directed and undirected values coincide. We also determine the supremum of the possible ratios of these fractional parameters, which turns out to be e, the basis of the natural logarithm.     

Growth of polar axis oriented tetragonal Pb(Zr,Ti)O3 films on CaF2 substrates with transparent (La0.07Sr0.93)SnO3

Epitaxial (La_0.07Sr_0.93)SnO₃ [LSSO] films were deposited on CaF₂ substrates by pulse laser deposition. The (1 0 0)_c orientation of LSSO films was observed only on (1 1 0)CaF₂, whereas (1 1 0)_c orientation was found on (1 1 1)CaF₂ and (1 0 0)CaF₂. (0 0 1) polar axis oriented tetragonal Pb(Zr_0.35Ti_0.65)O₃ films were grown on the fabricated (1 0 0)_cLSSO∥(1 1 0)CaF₂ by pulsed metal organic chemical vapor deposition. The (0 0 1)Pb(Zr_0.35Ti_0.65)O₃∥(1 0 0)cLSSO∥(1 1 0)CaF₂ stack structure exhibited about 70% transparency with an adsorption edge of approximately 330 nm.     

Asymmetric Organocatalysis with Sulfones

Asymmetric organocatalysis has become a powerful tool for the synthesis of optically active compounds. Whereas early research mainly focused on combining simple reagents as a proof‐of‐concept for asymmetric organocatalysis, recent investigations are directed towards extending the concept to more target‐ and diversity‐oriented synthesis. As a result of the many transformation possibilities and their ability to generate both nucleophilic and electrophilic reaction partners, sulfones have become especially important substrates in the field of organocatalysis.     

第二型面积分与流量问题

从物理和数学的角度讨论了一些在第二型面积分的教学中遇到的问题,通过讨论可消除学生在学习这部分内容时有关不可压缩流体的误解,并完善一些教科书的相关表述.     

The Crystallization of Poly (3-dodecylthiophene) in an Oriented Solidification Environment

The crystallization behaviors of poly (3-dodecylthiophene) (P3DDT) under two different oriented solidification conditions, I.e., two different relative relations (90° and 180°) between the directions of gravity and solidification, were investigated. X-ray diffraction results reveal that although similar layered structures are formed, under the condition of the relative relation 180°, temperature gradient has greater effects on the perfect degree of the layered structures of P3DDT. It also can be concluded that after recrystallization, the layered structures of P3DDT can be improved at relative relation 90o, but the orderly degree of the arrangements of alkyl side chains are not improved yet, even is reduced for both of the oriented solidification conditions.     

A Silicon Plasma-Based Wideband Modulator

Theoretical and experimental analysis has been performed for surface oriented silicon plasma-based p,i,n structures used to control high power level, broadband devices. It is shown that these structures are very promising for their use as modulators in the millimeter and submillimeter wave range.     

Quasi-Optical Sensors for Investigation of Acousto-Electromagnetic Phenomena of Popocatepetl Volcano

This article focuses on meteorological electronics based on the space research of acoustic-electromagnetic phenomena caused by Popocatepetl volcano (Mexico). The main purpose is to present two different types of quasi-optical sensors, one of them is formed by a modulator based on a surface oriented p,i,n structure with deep junctions; and by a silicon detector (avalanche photodiode with separated regions of absorption and multiplication: APDSAM). This system guarantee both good sensibility and wide range of sensing, sub-millimeter and millimeter range. This sensor has the advantage that can be realized as a planar array. On the other hand, for the remote measurement of basic meteorological parameters and chemical state by means of radiobrightness temperatures (radiometer systems) a low noise receiver on the base of dielectric waveguide and Schottky diodes cooled by means of cryoelectronic element is used.     

On the Connection Between Oriented Percolation and Contact Process

We study the contact process in ^d and a family of two-parametric oriented percolation models in ^d × ₊. It is proved that the derivative at the endpoint of the critical curve for percolation exists and its absolute value coincides with the critical rate for the corresponding contact process.     

单轴取向聚对苯二甲酸乙二酯非等温结晶动力学研究

采用等速升温DSC方法对单轴取向聚对苯二甲酸乙二酯 (PET)的结晶过程进行了研究 ,发现单轴取向PET的冷结晶峰表现为多重结晶峰 .等温DSC方法的研究结果进一步证实结晶重峰的存在 .为此 ,本文提出了一种依据非等温DSC曲线解析高聚物结晶动力学参数的新方法 .对单轴取向PET的研究结果表明 ,与其他方法相比较 ,由新方法计算出的理论曲线与实验数据能更好地吻合 .单轴取向PET的总的结晶过程由三个子结晶过程组成 .根据不同拉伸比 ,各个子过程的Avrami指数和质量分数的变化 ,对结晶机理进行了解释 .与各向同性PET样品相比 ,单轴取向PET在低温部分的结晶速率明显增快