Glyoxal Ozonation Process in Aqueous Solution

The process of ozonation of glyoxal in aqueous solution has been studied by following its chemical and kinetic evolution. Results show that the oxidative process leads to formation of carboxylic functions and carbon dioxide according to a constant selectivity ratio at varying conversion degree.. Comparison between the oxygen amounts of reaction products and the corresponding ozone consumptions reveals that molecular oxygen takes part in the reaction process. System behavior is explained on the basis of radical reaction mechanism.     

Preparation of ZrC/SiC porous self-supporting monoliths via sol-gel process using polyethylene glycol as phase separation inducer

We present a straightforward method via sol-gel process using polyethylene glycol (PEG) as phase separation inducer to prepare zirconium carbide/silicon carbide (ZrC/SiC) porous monoliths. Organic/inorganic hybrid gels are prepared using zirconium oxychloride, furfuryl alcohol, and tetraethyl orthosilicate as major starting materials. In the presence of PEG, crack-free hybrid monoliths are obtained by drying the wet gels under ambient pressure, whereas in the absence of PEG, the wet gels break into pieces as expected. PEG plays a key role in maintaining the macroscopic shape of the monoliths. After ceramization at 1300–1500?°C, ZrC/SiC porous monoliths are obtained. SEM and mercury intrusion porosimetry data show that PEG also has strong influence on the microstructures of the monoliths. The compressive strengths of the ceramic monoliths are in the range of 0.3 to 0.7?MPa. And their compressive behavior starts to differ due to the changes in their microstructures, especially the pore structure.     

Preparation of nanocrystalline nickel oxide from nickel hydroxide using spark plasma sintering and inverse Hall-Petch related densification

Nanocrystalline nickel oxide (NiO) was prepared from nickel hydroxide by Spark plasma sintering (SPS) and the mechanisms involved in the densification of NiO were studied. Reverse precipitated nickel hydroxide powders were SPS processed at 400, 600 and 700?°C with 70?MPa pressure. Pure NiO with 12?nm crystallite size formed after 400?°C sintering process. However NiO grains had grown to 18 and 38?nm after 600 and 700?°C sintering respectively. NiO pellets prepared using 600 and 700?°C SPS sintering schedules had relative densities of 83% and 94% respectively. Two displacement rate regimes were observed during densification of NiO in both 600 and 700?°C sintering processes. Decomposition of nickel hydroxide and particle sliding of NiO led to first displacement rate maximum while inverse Hall-Petch based plastic deformation facilitated densification during the constant second displacement rate regime. No densification occurred during sintering holding times indicating the limited role that diffusion played during densification.     

橡胶粒子尺寸对ABS树脂性能的影响

通过乳液聚合制备了橡胶粒子尺寸为64～420 nm的丙烯腈-丁二烯-苯乙烯(ABS)共聚物.然后将其与SAN-T树脂熔融共混制备橡胶质量分数为15%的ABS树脂.研究了橡胶粒子尺寸对ABS树脂力学性能影响和材料内部形态结构.结果表明:随着橡胶粒子尺寸的增加ABS树脂的冲击韧性提高.当橡胶粒子尺寸在320 nm时,拉伸强度达到最大,ABS树脂的综合性能达到最好.粒子尺寸在64～110 nm时,橡胶粒子在基体内部发生团聚,材料发生脆性断裂.当橡胶粒子尺寸在216～420 nm时,材料主要以韧性断裂为主,发生脆韧转变.具有双峰分布ABS-110nm/ABS-275 nm共混物大、小橡胶粒子间发生明显的协同作用.     

对甲基苯磺酸盐的合成与热重分析--碱土金属及过渡金属

合成了一系列碱土金属(Ca,Ba)和过渡金属(Fe,Mn,Co,Ni,Cu,Zn,Cd)对甲基苯磺酸盐,用热重分析仪在动态空气气氛下研究对甲基苯磺酸盐中结晶水个数和热分解产物,并探讨了其相对热稳定性。研究结果表明,除对甲基苯磺酸钙、对甲基苯磺酸钡和对甲基苯磺酸镉为无水盐外,其它对甲基苯磺酸盐都含有5或6个结晶水。碱土金属对甲基苯磺酸盐的最终热分解产物为金属硫酸盐,过渡金属对甲基苯磺酸盐的最终热分解产物为金属氧化物。并初步推断碱土金属和过渡金属对甲基苯磺酸盐的结构可能不同,但它们都具有较好的相对热稳定性。     

Transition metal oxides on organic semiconductors

Transition metal oxides (TMOs) on organic semiconductors (OSs) structure has been widely used in inverted organic optoelectronic devices, including inverted organic light-emitting diodes (OLEDs) and inverted organic solar cells (OSCs), which can improve the stability of such devices as a result of improved protection of air sensitive cathode. However, most of these reports are focused on the anode modification effect of TMO and the nature of TMO-on-OS is not fully understood. Here we show that the OS on TMO forms a two-layer structure, where the interface mixing is minimized, while for TMO-on-OS, due to the obvious diffusion of TMO into the OS, a doping-layer structure is formed. This is evidenced by a series of optical and electrical studies. By studying the TMO diffusion depth in different OS, we found that this process is governed by the thermal property of the OS. The TMO tends to diffuse deeper into the OS with a lower evaporation temperature. It is shown that the TMO can diffuse more than 20 nm into the OS, depending on the thermal property of the OS. We also show that the TMO-on-OS structure can replace the commonly used OS with TMO doping structure, which is a big step toward in simplifying the fabrication process of the organic optoelectronic devices.     

Property Restitution and Private Rental Housing in Transition: The Case of the Czech Republic

The objective of this paper is to explain one phenomenon evident in the transformation of post-socialist states that has received insufficient scholarly attention to date: the restitution of the housing stock in terms of its causes and consequences. In this paper, the theory of social constructivism, including Kemeny's advanced application of this theory to the field of housing studies, is used to (a) explain the causes for a particular type of property restitution in the Czech Republic and (b) outline its consequences on the role and long-term social meaning of private rental housing. This research explains how restitution was viewed by the main participants in this discourse, and how the whole process was legitimised and socially constructed in the Czech Republic. The evidence presented stems from a multi-method analysis of discourse that integrates the results of in-depth interviews, content analysis of the press, and an analysis of data from attitude surveys. The paper shows how the initial state of consensus surrounding the image of restitution quickly dissolved. The emergence of divisions combined with the inadequate response of the state generated a biased image of private rental housing among Czech citizens—a pattern that persists to the present.     

An analysis of the transition proportion for binarization in handwritten historical documents

In this paper, we will present a mathematical analysis of the transition proportion for the normal threshold (NorT) based on the transition method. The transition proportion is a parameter of NorT which plays an important role in the theoretical development of NorT. We will study the mathematical forms of the quadratic equation from which NorT is computed. Through this analysis, we will describe how the transition proportion affects NorT. Then, we will prove that NorT is robust to inaccurate estimations of the transition proportion. Furthermore, our analysis extends to thresholding methods that rely on Bayes rule, and it also gives the mathematical bases for potential applications of the transition proportion as a feature to estimate stroke width and detect regions of interest. In the majority of our experiments, we used a database composed of small images that were extracted from DIBCO 2009 and H-DIBCO 2010 benchmarks. However, we also report evaluations using the original (H-)DIBCO?s benchmarks.     

DFT study of the oxygen reduction reaction on iron,cobalt and manganese macrocycle active sites

The best performing non-precious metal based catalysts for polymer electrolyte membrane fuel cells are manufactured by incorporation of nitrogen into a carbon structure in the presence of iron and cobalt. Herein, density functional theory (DFT) calculations have been performed to investigate the oxygen reduction reaction on catalyst active sites modelled as transition metal macrocycles with iron, cobalt or manganese central atoms. The effects of the transition metal and macrocycle structure have been investigated. The structure of the most promising active sites has been proposed, and the detailed potential energy profiles of the oxygen reduction reaction have been obtained over the active sites, including all intermediate steps with corresponding activation barriers. The efficiency of the active sites depends primarily on the transition metal nature, and the central iron atom accounts for the higher catalytic activity than cobalt and manganese. The central manganese atom can favour the two-electron oxygen reduction pathway and thus yielding hydrogen peroxide.