Polymer-Derived High-Temperature Nonoxide Materials: A Review

This review is focused on an attractive class of polymer-derived high-temperature ceramics, namely, polymer-derived nonoxide materials. With a brief introduction of high-temperature nonoxides, the origin of using polycarbosilane (PCS) polymer melt spinning to synthesize silicon carbide (SiC) fibers is traced back. For SiC formation, the four stages for the conversion from polymer precursors to microcrystalline ceramics are examined first: crosslinking, polymer decomposition, ceramic formation, and crystallization. Also, the important parameters related to PCS pyrolysis are explained, and polymer-derived SiC microstructures and compositions are evaluated. Solid-solution carbides and transition metal carbides are further reviewed. For boride materials, the discussion is focused on transition metal borides and boride composites. Similar to PCS conversion to SiC, nitride materials mostly start with polycarbosilazane (PSZ) precursors and form into the final materials through pyrolysis. With different carbide and nitride precursors mixed and pyrolyzed together, high-temperature nonoxide composites are formed. Such molecular-level intermixing and versatile capability of forming different shapes enable many exciting properties. Among these are mechanical and thermal properties, along with electrical conductivity, electromagnetic shielding, and charge storage capability. An overview of applications of polymer-derived nonoxides is provided, followed by a summary and outlook.     

A Survey of Hospital Psychology in Canada.

Despite the major advances in health psychology over the past decade and the changes that have taken place in the Canadian health sector, there remains a paucity of information available about the structure of psychological services in Canadian health-care settings. The most current information about psychology in Canada's hospitals was gathered in 1982 - almost 20 years ago (Arnett, Martin, Steiner, & Goodman, 1987). This article updates the previous information, as it presents the results of a survey that was sent to 975 acute, psychiatric and continuing care health facilities with a minimum patient bed count of 100. Detailed information about the number of psychologists and administrative organizations of psychological services in Canada are reported. The range of services provided by psychologists in health-care settings has expanded, and professional autonomy, as shown by the existence of independent departments of psychology, has changed. The implications of these results for the organization and delivery of psychological services in Canadian healthcare, and for advocacy on the part of psychology, are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social Cognitive Predictors of Domain and Life Satisfaction: Exploring the Theoretical Precursors of Subjective Well-Being.

Central variables of social cognitive theory were adapted to forge an integrative model of well-being, which was designed to offer greater utility for therapeutic and self-directed change efforts than the dominant personality view of well-being. The authors present 2 studies using versions of the social cognitive model to predict domain-specific and overall life satisfaction. In both studies--one nomothetic, the other idiographic in measurement approach--findings indicated that satisfaction in particular life domains is predicted by domain-specific social cognitive variables (e.g., self-efficacy, perceived goal progress, environmental resources). Domain satisfaction in valued life domains also explained unique variance in overall life satisfaction, even after controlling for trait positive affectivity or extraversion. Implications for theory, research, and counseling aimed at well-being promotion and maintenance are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Occurrence of Textile Dyes and Metals in Tunisian Textile Dyeing Effluent: Effects on Oxidative Stress Status and Histological Changes in Balb/c Mice

Although it is known that textile wastewater contains highly toxic contaminants whose effects in humans represent public health problems in several countries, studies involving mammal species are scarce. This study was aimed to evaluate the toxicity profile of 90-days oral administration of textile dyeing effluent (TDE) on oxidative stress status and histological changes of male mice. The TDE was collected from the textile plant of Monastir, Tunisia and evaluated for the metals, aromatic amines, and textile dyes using analytical approaches. Metal analysis by ICP-MS showed that the tested TDE exhibited very high levels of Cr, As, and Sr, which exceeded the wastewater emission limits prescribed by WHO and Tunisian authority. The screening of TDE through UPLC-MS/MS confirmed the presence of two textile dyes: a triphenylmethane dye (Crystal violet) and a disperse azo dye (Disperse yellow 3). Exposure to TDE significantly altered the malondialdehyde (MDA), Conjugated dienes (CDs), Sulfhydryl proteins (SHP) and catalase levels in the hepatic and renal tissues. Furthermore, histopathology observation showed that hepatocellular and renal lesions were induced by TDE exposure. The present study concluded that TDE may involve induction of oxidative stress which ensues in pathological lesions in several vital organs suggesting its high toxicity. Metals and textile dyes may be associated with the observed toxicological effects of the TDE. These pollutants, which may have seeped into surrounding rivers in Monastir city, can cause severe health malaise in wildlife and humans.     

Mapping and interpreting soil textural layers to assess agri-chemical movement at several scales along the eastern seaboard (USA)

Despite numerous cases of groundwater contamination with agricultural chemicals on layered sandy soils, monitoring and prediction of the fate of these chemicals in the vadose zone has eluded researchers and bureaucrats alike so far. To aid in a better understanding of this phenomena, the movement and fate of agricultural chemicals were assessed at different scales for the (sandy and layered) floodplain soil occurring along the Eastern Seaboard. At the point and field scale ground penetrating radar was used to locate the coarse sand lenses and tracer experiments were initiated to study the flow pattern of the chemicals. Results show that water and solutes moved over the coarse layers and were funneled into fingers bypassing most of the soil matrix and reaching the groundwater much faster than when the solute would move evenly through the vadose zone. At field scale a computer simulation indicated that the exact location of the layers does not have to be known for calculating travel times, indicating that pedo-transfer functions could be developed for calculating groundwater pollution potential for different combinations of soil and chemicals. In the future, groundwater pollution on a regional scale can be predicted by using these pedo-transfer functions in a Geographic Information System.     

Maternal supplementation with CLA decreases milk fat in humans

CLA refers to isomers of octadecadienoic acid with conjugated double bonds. The most abundant form of CLA (rumenic acid (RA): c9,t11-18∶2) is found in milk and beef fat. Further, CLA supplements containing RA and t10,c12−18∶2 are now available. Consumption of commercially produced CLA has been shown to decrease adipose accretion in growing laboratory and production animals and cause milk fat depression in cows. We tested the hypothesis that CLA supplementation would increase milk CLA concentration and decrease milk fat content in humans. Breastfeeding women (n=9) participated in this double-blind, placebo-controlled, crossover study divided into three periods: intervention l (5 d), washout (7 d), and intervention II (5 d). Women were randomized to treatment order. During each intervention period, women consumed 1.5 g of CLA supplement or placebo (olive oil) daily; during the washout period, no supplements were consumed. Milk was collected by complete breast expression on the final day of each period; milk output was estimated by 24-h weighing on the penultimate day of each intervention period. Milk RA and t10,c12−18∶2 concentrations were greater (P<0.05) during the CLA treatment period as compared to the placebo period. Milk fat content was significantly lower during the CLA treatment, as compared to the placebo treatment (P<0.05). Data indicate no effect of treatment on milk output. Therefore, it would be prudent that lactating women not consume commercially available CLA supplements at this time. This paper was published in part in Masters, N., McGuire, M.A., and McGuire, M.K. (1999) Conjugated Linoleic Acid Supplementation and Milk Fat Content in Humans, FASEB J. 13, A697.     

Young children associate novel words with complex objects rather than salient parts.

How do children learn associations between novel words and complex perceptual displays? Using a visual preference procedure, the authors tested 12- and 19-month-olds to see whether the infants would associate a novel word with a complex 2-part object or with either of that object's parts, both of which were potentially objects in their own right and 1 of which was highly salient to infants. At both ages, children's visual fixation times during test were greater to the entire complex object than to the salient part (Experiment 1) or to the less salient part (Experiment 2)--when the original label was requested. Looking times to the objects were equal if a new label was requested or if neutral audio was used during training (Experiment 3). Thus, from 12 months of age, infants associate words with whole objects, even those that could potentially be construed as 2 separate objects and even if 1 of the parts is salient. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formation of Metal Carbide Powder by Spark Machining of Reactive Metals

When metals or alloys are subjected to electrical discharges in a dielectric fluid, the molten metal frequently reacts with the fluid or with ionic fragments generated from the dielectric by the discharge. When hydrocarbon fluids are used as dielectrics, the reaction products are metal carbides. These carbides are present both as surface layers on the metal samples and as fine powder particles produced when material is ejected from the surface by the sparks. Results are reported here on a study of the formation of fine carbide powder by the spark machining of Ti, Zr, and W. Spark machining of Ti and Zr produced the NaCl structure carbide expected of these metals, though under some machining conditions the powder produced by the machining also contained fine dispersion of the parent metal or graphite. Machining of W produced hexagonal structure W₂C and WC in both the NaCl and the hexagonal structural forms. X-ray diffraction studies showed that the carbon concentration of these powders depended upon the frequency and polarity of the applied current pulses and upon other processing variables. The X-ray studies and scanning electron microscopy of the powders and of the surfaces from which they were generated showed that carburization reactions occurred both in the molten pools produced on the sample surfaces by the electric discharges and within fine particles after they were ejected from the surfaces.     

Effect of Antioxidant Solubility and Concentration on Discoloration of Beef Vertebrae Marrow during Display

ABSTRACT:  Two experiments were conducted to assess the role of aqueous- and lipid-based antioxidants in preventing or limiting beef lumbar vertebrae marrow discoloration. In experiment 1, lumbar vertebrae ( n = 8 replications) were treated with either 0%, 1.5%, or 2.5% (wt/wt) of ascorbic acid or ascorbate-6-palmitate. Vertebrae color (visual and L*a*b*) was evaluated during 5 d of display at 1 °C in high-oxygen modified atmosphere packaging (MAP; 80% oxygen/20% carbon dioxide). Ascorbic acid treatments minimized ( P < 0.05) discoloration compared with ascorbate-6-palmitate. In experiment 2, lumbar vertebrae ( n = 8 replications) were treated with 0, 0.06 M, or 0.10 M ascorbic acid and ascorbate-6-palmitate, packaged in high-oxygen MAP, and displayed for 5 d (1 °C). During display, vertebrae treated with ascorbic acid had a redder color ( P < 0.05) than those treated with ascorbate-6-palmitate, and both treatments were redder ( P < 0.05) than untreated controls. To better understand the mechanism of beef bone marrow discoloration, future work might address the hydrophobic antioxidants' lack of effectiveness and the potential localization of components responsible for bone discoloration within the aqueous phase of erythropoietic marrow.     

Neighbourhood regeneration: facilitating community involvement

In this paper, the courses of action taken to facilitate residents' participation, in developing community action plans, in two Australian public housing estate regeneration projects are examined. The findings are placed within the context of changes, over the past 20 years, to the operation of housing authorities that were antecedents to the newly emerging partnership models of regeneration between the public and private sectors and communities. Three major findings are highlighted. First, the government role, in terms of providing support positions and allowing adequate time for residents to participate is critical to the success of community participation activities. The second finding is that the ever-increasing privatisation of public sector activities and pre-occupation with developing a more efficient, effective and lean public sector, essentially defined in economic terms, is in conflict with meeting government social goals of community participation. Third, much of the rhetoric used in neighbourhood regeneration projects of 'rights and obligations' and 'sustainability' is not well defined and is sometimes implemented in contradictory ways. In applying these terms, the housing authorities and their regeneration partners need to elucidate the principles they are promoting. In light of the findings overall, it is concluded that we should question the capacity of market oriented regeneration policy to lead to resident inclusion.