Flash sintering of a three‐phase alumina,spinel, and yttria‐stabilized zirconia composite

Three‐phase ceramic composites constituted from equal volume fractions of α‐Al₂O₃, MgAl₂O₄ spinel, and cubic 8 mol% Y₂O₃‐stabilized ZrO₂ (8YSZ) were flash‐sintered under the influence of DC electric fields. The temperature for the onset of rapid densification (flash sintering) was measured using a constant heating rate at fields of 50‐500 V/cm. The experiments were carried out by heating the furnace at a constant rate. Flash sintering occurred at a furnace temperature of 1350°C at a field of 100 V/cm, which dropped to 1150°C at a field of 500 V/cm. The sintered densities ranged from 90% to 96%. Higher electric fields inhibited grain growth due to the lowering of the flash temperature and an accelerated sintering rate. During flash sintering, alumina reacted with the spinel phase to form a high‐alumina spinel solid solution, identified by electron dispersive spectroscopy and from a decrease in the spinel lattice parameter as measured by X‐ray diffraction. It is proposed that the solid solution reaction was promoted by a combination of electrical field and Joule heating.     

N,N,N-trimethyl chitosan as an efficient antibacterial agent for polypropylene and polylactide nonwovens

The paper presents a method of depositing N,N,N-trimethyl chitosan (TMC) layers onto polypropylene and polylactide nonwovens. A two-step modification procedure is applied: first, grafting the nonwovens with acrylic acid and next layer-by-layer deposition. Turbidimetric measurements confirm the creation of polycomplexes between grafted poly(acrylic acid) and deposited TMC. The created material structure is evaluated using gravimetric analysis, reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy measurements and pH-metric titration. The modified material exhibits good antibacterial properties against Gram-positive bacteria Staphylococcus aureus.     

Effects of oil dispersants and oil emulsions on marine animals

The toxicities to marine animals of nine oil dispersants, three oil emulsions with Corexit and of a dispersion of Oman crude oil, have been studied in continuous flow aquarium systems at 96-h exposures followed by a recovery period in clean sea-water. New types of dispersants were found to be less toxic than older types and oil emulsions more toxic than dispersants alone or crude oil alone. Fishes and bivalves were found most sensitive. Crustaceans were the most resistant to dispersants but very susceptible to oil emulsions. The tolerance of different species was found to be related to their mode of life, more active species being more susceptible. Delayed mortality of bivalves increased their susceptibility if the recovery period was included. Effects on locomotory behaviour of fishes and crustaceans, breathing rate of fish, valve-closure of bivalves and byssal thread formation of common mussels have been demonstrated for both dispersants and oil emulsions. The general sequence of such effects was: increased activity; successively impaired activity; immobilization; and death. Recovery is good for fish and crustaceans but poor for bivalves due to the delayed effects. Ecological consequences of dispersants and oil pollution in the marine environment are discussed.     

NMR spectroscopy for determination of cationic polymer concentrations

Organic polyelectrolytes are utilized extensively in wastewater treatment, but their fate after use is poorly understood. Analytical methods used for polymer determination in less complex systems appear to fail in application to wastewater systems, contributing to the lack of knowledge. Thus, the development of 1H NMR spectroscopy is reported here for specifically quantitating certain cationic flocculant polymers in environmental samples. Proton observe frequencies of 250 or 400 MHz proton were used. A copolymer of acrylamide and acryloyloxyethyltrimethylammonium chloride was used, representative of cationic flocculant polymers possessing quaternary ammonium groups with terminal methyls that provide a sharp singlet at a chemical shift of approximately 3.06 ppm. A strong linear relationship was demonstrated between polymer concentration and either height or area of this peak. Recoveries were up to 96% at higher concentrations (250 mg/L), and were greater than when using viscosity or charge titration methods for polymer determination. Lesser recoveries at lower concentrations (70% at 5 mg/L) were attributed to adsorptive losses. The detection limit of this method was determined to be <0.5 mg/L. Use of the method was exemplified by analysis of anaerobically digested sludges for residual polymer following a range of dosages, showing the resulting isotherm.     

波哥大城市公共空间的改革

波哥大是哥伦比亚的首都,城市位于国家中部海拔2600m的高原上。自1999年以来,首都经历了一场重大的改革,这项改革利用公共空间规划与可持续城市交通作为主要手段以营造更人性化的城市环境。介绍重要事件、项目、实践以及帮助推进波哥大城市形成的人物,重点论述公共空间改革过程与园林设计师的职责。著名的波哥大公共空间改革主要分为以下几个具体内容：步行区、道路基础设施(特别是自行车专用道的实施)、公园与绿道的改造恢复、城市绿化以及“千年捷运”巴士快速公交系统。1999-2004年之间,城市经历了高速投资,并完成了一系列重要基础设施项目。尽管波哥大的变化在空间上看起来最为明显,实际上改革已经影响到城市生活的方方面面。     

Parental expressed emotion toward children: Prediction from early family functioning.

Expressed emotion (EE), an index of family member criticism and emotional overinvolvement, predicts outcome among adults and children with mental disorders. However, limited research exists on factors contributing to EE. Aims of the current study were to (a) examine EE in mothers of young children; (b) assess relationships between demographic factors and EE in a diverse sample; and (c) investigate whether family stress and functioning, including quality of marital relationship, life events, maternal stress, and family environment, predict EE. In the current study, 276 mothers completed questionnaires when their children were between 1 and 3 years of age and a measure of EE when their children were in kindergarten. Results indicated that family expressiveness was the most consistent predictor of EE. Further research seems warranted to better delineate associations between family functioning and EE. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interdependence of parenting of mothers and fathers of infants.

This study examined the relations among parenting behaviors of 97 coresident mothers and fathers of infants during a dyadic free-play setting. The authors examined the extent to which observed sensitive and intrusive parenting behaviors in mother-child and father-child dyads were related and how perceived marital quality may be associated with the similarity between maternal and paternal parenting behaviors. The authors found support for interdependence of parenting by mothers and fathers. High perceived marital quality was associated with interdependence of sensitive parenting behaviors in mother-infant and father-infant interactions. Negative parenting behaviors by mothers and fathers were interrelated regardless of marital quality. The findings highlight the importance of studying parenting by mothers and fathers as embedded within particular family systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MOCVD as a dry deposition method of ZnSe buffers for Cu(In,Ga)(S,Se)2 solar cells

ZnSe prepared by metal organic chemical vapor deposition is used as a buffer layer in Cu(In,Ga)(S,Se)₂ solar cells without any utilization of wet chemistry. Cell efficiencies are as good as cells with the conventional CdS buffer. Stability of unencapsulated cells under damp heat conditions is somewhat lower for the alternative buffer. The first stages of photoassisted growth are studied. X‐ray photoemission spectroscopy shows that a continuous layer is formed. Copyright © 2004 John Wiley & Sons, Ltd.     

Fabrication of nano N-doped In2Ga2ZnO7 for photocatalytic hydrogen production under visible light

N-doped In₂Ga₂ZnO₇ photocatalysts were fabricated by solid state reaction route. All the prepared photocatalysts were successfully characterised by PXRD, optical absorption spectra, SEM, TEM, XPS, BET surface area and photoresponse studies. The formation of In₂Ga₂ZnO₇ was confirmed by the PXRD pattern. Optical absorption spectra showed that the visible light absorption of all the photocatalysts were enhanced by nitrogen doping. Among all the prepared photocatalysts, 1 wt% Pt loaded N-GaInZn-500 showed enhanced photocatalytic activity towards hydrogen evolution under visible light irradiation in presence of 10 vol% methanol solution as sacrificial agent. The excellent photocatalytic activity of N-GaInZn-500 is in agreement with N-content, bandgap energy, PL intensity and Surface area.