Diets of the benthic amphipod Diporeia in southern Lake Michigan before and after the dreissenid invasion

Diporeia spp. were a key component of the Great Lakes benthos, converting the pelagic algal rain to secondary production, which is critical for Great Lakes fishes. However, Diporeia declines since the 1980s have been rapid and widespread. While there are temporal relationships between Diporeia declines and spread of zebra and quagga mussels, establishing a mechanistic link has been difficult. Diporeia declines may result from competition for food resources with dreissenid mussels; however, conflicting evidence suggests food limitation may not be the direct link. To test food limitation, we analyzed gut contents of Diporeia collected between the 1980s and 2009 from two deep (>100 m) and one nearshore station (~50 m depth) in southern Lake Michigan. We further analyzed sediment cores from the same stations to resolve relationships among food resources, Diporeia diet, and diet selectivity during pre- and post-dreissenid invasion. In spring, pre-dreissenid Diporeia fed selectively and exclusively on large (Stephanodiscus) and filamentous centric diatoms (Aulacoseira). Diporeia diets showed significant shifts during the 2000s to greater proportions of small centric and araphid diatoms, coincident with Diporeia declines and offshore expansion of quagga mussels. Sediment cores recorded declines in Aulacoseira and large Stephanodiscus from 1960 to 2009 and increases in small centrics after dreissenid introduction. Accounting for high selectivity in springtime Diporeia diets, community changes in sediment records are consistent with changes observed in Diporeia diets and suggest Diporeia declines have been exacerbated by a shift from more nutritious and highly preferred diatom species to less nutritious and negatively selected species.     

Self-expressiveness within the family context: Psychometric support for a new measure.

The family appears to be an important setting for learning about emotions and how to express them within a social context. Because of the need for reliable and valid measures of emotional expressiveness in the family, the Self-Expressiveness in the Family Questionnaire is introduced and evaluated in four studies with 499 mothers and 362 fathers. Factor analyses indicate highly consistent patterns of loadings for a two-factor solution across the four studies. The resulting positive and negative scales are highly internally consistent and stable over time. Evidence of good convergent, discriminant, and construct validity was obtained, and a preliminary short form with good internal consistency and construct validity was also identified. Ideas for future research on marital and parent–child issues are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CARBON FIBER-POLYANILINE COMPOSITES: KINETICS OF ELECTRODEPOSITION OF POLYANILINE ONTO CARBON FIBERS BY CYCLIC VOLTAMMETRY

Homogeneous and uniform coatings of polyaniline were successfully deposited on carbon fibers by an aqueous electrodeposition technique using p-toluene sulfonic acid as the electrolyte. Electrochemical deposition of aniline was carried out by cyclic voltammetry in the potential range of -0.2 V to 1.0 V versus saturated calomel electrode (SCE). The electrochemical deposition parameters such as the number of cycles, scan rate (SR), initial monomer ([M]), and electrolyte concentration ([E]) were systematically varied. The amount of composite coatings on carbon fibers was dependent on the electrochemical deposition parameters. From a weight gain analysis, the rate of the reactions (R p ) was calculated. As the aniline concentration was increased up to 0.35 M and electrolyte concentration up to 0.5 M, the deposition rate also increased, whereas an increase in scan rate decreased the deposition rate. Kinetic analysis showed that the rate equation for the p-toluene sulfonic acid system is R p ∝SR -1.25 [M] 0.73 [E] 0.95 . IR spectra also showed an increase in the deposition of polyaniline coatings on carbon fibers with a decrease in the scan rate and an increase in both monomer and electrolyte concentration. The ratio of two oxidation states of polyaniline obtained during electrodeposition, namely emeraldine and pernigraniline, can be varied by changing the electrochemical deposition parameters.     

Synthesis and characterisation of thermo-sensitive terpolymer hydrogels for drug delivery applications

In this study, thermo-sensitive terpolymer hydrogels based on N-tert-butylacrylamide (NtBAAm), N-isopropylacrylamide (NIPAAm) and N-vinyl pyrrolidone (NVP) were successfully photopolymerised and characterised. 1-hydroxy-cyclohexylphenylketone (Irgacure 184) and 2-hydroxy-2-methyl-1-phenyl-propanone (Irgacure 2959) were used as light-sensitive initiators to initiate the reactions. Chemical structures of the hydrogels were confirmed using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The hydrogels were also characterised using modulated differential scanning calorimetry (MDSC) for their glass transition and phase transition temperatures. A single glass transition temperature (T _g ) was observed, further confirming successful formation of a terpolymer. The hydrogels were thermo-responsive, exhibiting a decrease in lower critical solution temperature (LCST) as the NtBAAm weight ratio was increased. Pulsatile swelling studies indicated that the hydrogels had thermo-reversible properties and the swelling properties were dependent on test temperature, monomer feed ratios and crosslinker content. The proposed hydrogel system could find applications in a broader field of gel/drug interaction, for the development of controlled release and targeted delivery devices.     

Polyimide-b-polysiloxane Copolymers: Synthesis and Properties

This review discusses the synthesis, structure and properties of polyimide-b-polysiloxane copolymers. Polysiloxane modified polyimides has become an important class of materials over the past 20 years because of their ease of processing and interesting properties. Although polyimides are widely used in engineering applications because of their outstanding mechanical properties and thermal stability, their processability, toughness, and adhesion can be significantly enhanced by incorporation of polysiloxanes. The synthesis of polyimide-b-polysiloxane copolymers is performed by a one-step copolymerization method or a two-step method, resulting in a wide range structures and thermo-mechanical properties. The initial modulus and thermal stability of polyimide-b-linear polysiloxane copolymers can be further improved by copolymerization with ladder-like polysiloxanes which possess outstanding thermal stability and mechanical properties. The study of synthesis and properties of polyimide-b-polysiloxane copolymers is essential because it provides a useful insight into the processing-structure–property relationship.     

Dehydroepiandrosterone alters lipid profiles in Zucker rats

High free fatty acid (FFA) levels are common in obesity and in diseases such as diabetes that are associated with the obese state. Dehydroepiandrosterone (DHEA) decreases dietary fat consumption, body fat content, and insulin levels in the obese Zucker rat (ZR), a genetic model of human youth-onset obesity and type 2 diabetes mellitus. This study was conducted to investigate the effects of DHEA on lean and obese ZR serum, adipose, and hepatic tissue fatty acid (FA) profiles and serum FFA levels. Because DHEA is known to decrease fat consumption and body fat, we postulate that DHEA may also alter FA profiles and FFA levels of the obese ZR such that they more closely resemble the profiles and levels of their lean siblings. In this study there was a DHEA and a pair-fed (PF) group (n=6) for 12 lean and 12 obese ZR. The diet of the treatment groups was supplemented with 0.6% DHEA, and PF groups were given the same average calories consumed by their corresponding DHEA group for 30 d. Fasted animals were sacrificed, and FA profiles and FFA levels were measured. Serum FFA levels were higher in obese (∼1 mmol/L) compared to lean rats (∼0.6 mmol/L). After 30 d of DHEA treatment, FFA levels were lower (P<0.05) in both lean and obese groups. Although several significant differences in FA profile of serum, hepatic, and adipose lipid components were observed between lean and obese ZR, DHEA-related changes were only observed in the serum phospholipid (PL) and liver PL and triglyceride fractions. The slight but significant decrease in serum FFA levels may be reflected by changes in serum PL FA profiles. Specific hepatic FA profile alterations may be related to DHEA's known effects in inducing hepatic peroxisomes. We speculate that such FA changes may give insight into a mechanism for the action of DHEA.     

Futuristic applications of hydrogen in energy,biorefining, aerospace,pharmaceuticals and metallurgy

The increasing world population, as well as demands for energy and industrial commodities, have led to an overall rise in anthropogenic greenhouse gas emissions. Moreover, demands for fossil fuels and petrochemicals are also gradually escalating in the developing and underdeveloped countries to sustain the transportation sector, industrial power generation and commodity chemical production. To address these challenges and to meet the Paris Agreement on climate change, there has been a growing interest in the development of renewable energy resources. Hydrogen is considered a strong candidate for the next-generation energy infrastructures as an energy carrier and vector, as well as a precursor or auxiliary component for several industrial processes. This review outlines current researches and applications of hydrogen in the processing and upgrading of hydrocarbon fuels, fuel cells, platform chemicals synthesis, pharmaceuticals, aerospace and maritime uses, metallurgy and electronics. Besides, applications of hydrogen as a direct fuel, synthesis of liquid hydrocarbons via Fischer-Tropsch process and syngas fermentation to alcohols are also reviewed. The specific utilization of hydrogen in the metallurgical industry is highlighted for metal reduction and in the oxyhydrogen flame for cutting and welding of metals. Besides, the article also describes the use of hydrogen in pharmaceutical industries for drug discovery. Finally, a variety of socio-economic aspects of hydrogen as a renewable fuel is also outlined in this article.     

Influence of catalyst bed temperature and properties of zeolite catalysts on pyrolysis-catalysis of a simulated mixed plastics sample for the production of upgraded fuels and chemicals

The pyrolysis-catalysis of a simulated mixture of plastics representing the plastic mixture found in municipal solid waste has been carried out to determine the influence of process conditions on the production of upgraded fuel oils and chemicals and gases. The catalysts used were spent zeolite from a fluid catalytic cracker (FCC), Y-zeolite and ZSM-5 zeolite. The addition of a catalyst to the process produced a marked increase in gas yield, with more gas (mainly C₁–C₄ hydrocarbons) being produced as the temperature of the catalyst was raised from 500 °C to 600 °C. The Si/Al ratio of the catalysts influenced the composition of other gases with the more basic catalysts producing more CO and the strongly acidic catalyst producing more H₂. The yield of product oil decreased with the addition of the catalysts, but the oil was of significantly lower molecular weight range, containing a product slate of premium fuel range C₅–C₁₅ hydrocarbons. In addition, the content of aromatic compounds in the product oil was increased; for example, benzene and toluene accounted for more than 90% of the aromatic content of the oil from the strongly acidic Y-zeolite catalysts. A reaction scheme is proposed for the production of single-ring aromatic compounds via pyrolysis-catalysis of plastics.     

Morphology and structure of the passive interphase formed during aqueous electrodeposition of polypyrrole coatings on steel

An iron(II) oxalate dihydrate passive interphase was electrodeposited on steel substrate from aqueous oxalate solutions prior to the electrochemical polymerization of pyrrole. The effect of electrochemical process parameters on the morphology and structure of the passive interphase was systematically investigated by scanning electron microscopy(SEM) and X-ray diffractometry (XRD). Our results reveal that the passive interphase is composed of a monolayer of closely packed crystals. The size of the crystals is dependent on the experimental conditions. The iron(II) oxalate dihydrate interphase formed on steel by electrochemical deposition has an orthorhombic structure irrespective of the reaction condition. The unit cell dimensions of the passive interphase formed by electrodeposition are slightly different from those formed by conventional chemical process.