Experimental and Numerical Study of the Effect of an Electric Field on a Bunsen-type Flame

The effect of an electric field on the behavior of premixed methane-air flames has been studied. A candle-type flame has been observed experimentally and analyzed for its geometrical proportions under an electric field. A numerical model has been developed to explain some of the experimental observations. The model employs a two-dimensional cylindrical coordinate system and assumes axial symmetry. The mass, momentum, species, and energy conservation equations are solved by an integrated version of the PHOENICS and CHEMKIN computer codes. It is concluded that the effect of the electric field on the flame behavior is mainly due to ionic wind effects.     

Development of collagen/PVA composites patches for osteochondral defects using a green processing of ionic liquid

Osteochondral defects are still a big challenge for the surgeons because of good biocompatibility and higher mechanical strength requiring issues of the implants. In this study, different concentrations of collagen (dissolved in ionic liquid) up to 60% were blended with polyvinyl alcohol to prepare hydrogels of good mechanical strength, with the best biocompatibility and excellent fluid uptake ability. Ionic liquid was used as a green solvent for dissolution of collagen at a higher concentration as compared to other normal solvents. The prepared hydrogels were characterized with Fourier transform infrared spectroscopy (FTIR) which showed the characteristic peaks assigned to collagen and PVA. The surface morphology was investigated using scanning electron microscopy (SEM) which revealed homogeneity of the composite patches. Thermal gravimetric analysis (TGA) performed for samples show good thermal stabilities. Fluid uptake ability showed the massive uptake of fluid by the hydrogels. Biocompatibility was tested using hemolysis and MTT assay. Electrodynamic fatigue testing system was used for evaluating the mechanical properties and measured the tensile strength in the range of 2.4 to 8.5?MPa. The prepared osteochondral patches show good biocompatibility and mechanical properties.     

Seismic vibrations in bulk blasting with high-precise electronic and nonelectric blasting systems at quarries

The authors report measurement data on seismic waves in bulk blasting at quarries by using new high-precise electronic and pyrotechnic blasting systems. It is proved that both systems are efficient, intensity of seismic waves is much lower in large-scale bulk blasting. The authors implemented numerical modeling of seismic wave propagation under a short-delay bulk blast at a quarry. Influence of the blast delay parameters and their precision on the maximum level of seismic vibrations has been studied, and their optimal ranges have been established.     

Miniaturization limitations of HCCI internal combustion engines

Small-scale energy conversion devices are being developed for a variety of applications. Notable are propulsion units for micro-aircraft vehicles (MAV). In spite of the fact that batteries have low energy density, batteries today power most of the micro aircrafts. Their low energy density significantly limits the aircraft performances. The high specific energy of hydrocarbon and hydrogen fuels, as compared to other energy storing means, like, batteries, elastic elements, flywheels, pneumatics, and fuel cells, appears to be an important advantage, and favors the internal-combustion-engine (ICE) as a candidate. In addition, the specific power (power per unit of mass) of the ICE is much higher than that of other candidates like fuel cells, photovoltaic, and battery units. Micro-engines are not simply smaller versions of full-size engines. Physical processes such as combustion, gas exchange, and heat transfer, are performed in regimes different from those occur in full-size engines. Consequently, engine design principles are different at a fundamental level, and have to be re-considered before they are applied to micro-engines. When a spark-ignition (SI) cycle is considered, part of the energy that is released during combustion is used to heat-up the mixture in the quenching volume, and therefore the flame-zone temperature is lower and in some cases can theoretically fall below the self-sustained combustion temperature. The flame quenching thus seems to limit the minimum dimensions of a SI engine. This limit becomes irrelevant when a homogeneous-charge compression-ignition (HCCI) cycle is considered. In this case friction losses and charge leakage through the cylinder-piston gap become dominant, constrain the engine size, and impose minimum engine speed limits. In the present work a phenomenological model has been developed to consider the relevant processes inside the cylinder of a homogeneous-charge compression-ignition (HCCI) engine. The lower possible limits of scaling-down HCCI cycle engines are proposed. The present work postulates the inter-relationships between the pertinent parameters, and proposes the lower possible miniaturization limits of IC engines.     

Alcohol outcome expectancies and alcohol use: A latent variable cross-lagged panel study.

The relation between alcohol outcome expectancies (EXP) and alcohol use was prospectively examined over 3 years in a mixed-gender sample of college students (N?=?465) at low and high risk for the development of alcoholism. Alcohol use remained fairly stable over 4 years, but EXP decreased significantly over the course of the study. Structural equation modeling techniques were used to examine reciprocal relations between EXP and alcohol use over 1- and 3-year intervals. Reciprocal prospective effects were demonstrated, but the nature of these effects appears dependent on the interval between measurement periods. Conceptually, these findings indicate both an etiologic role for EXP in predicting future alcohol use, and the influence of alcohol consumption on the development and maintenance of EXP. Methodologically, they point to the importance of the consideration of measurement interval in longitudinal research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure of P strain mice to respond to vaccination against schistosomiasis correlates with impaired production of IL-12 and up-regulation of Th2 cytokines that inhibit macrophage activation

In contrast to most inbred strains, P mice fail to develop significant resistance to Schistosoma mansoni infection as a result of vaccination with either radiation-attenuated cercariae or schistosome antigens plus Bacillus Calmette Guérin, and this failure correlates with defects in macrophage larvicidal activity. Supernatant fluids from antigen-treated in vitro cultures of splenocytes from vaccinated P mice demonstrate less macrophage stimulatory activity than do supernatants from cells of vaccine-responsive strains such as C57BL/6. This is not due either to diminished production of the macrophage-activating cytokine IFN-gamma by P mice, or to a lesser responsiveness of macrophages from P mice to activation by IFN-gamma. Rather, P splenocytes produce two-to threefold higher amounts of IL-4 and IL-10, cytokines which down-regulate the cytotoxic potential of IFN-gamma-treated macrophages. Thus, the macrophage-activating potential of cytokine preparations from vaccinated P mice can be completely recovered by in vitro treatment with antibodies to IL-4 or IL-10. Moreover, lower levels of IL-12, a cytokine involved in promoting development of Th1 responses, are produced by splenocytes from P mice as compared to C57BL/6 counterparts. These studies indicate that a genetic predisposition toward an impaired production of IL-12 and an increased production of down-regulatory Th2 cytokines correlate with low response to vaccination against S. mansoni.     

Genes, environment and individual differences in alcohol expectancies among female adolescents and young adults.

Alcohol expectancies are an important proximal causal risk factor in several models of the familial transmission of alcohol use, abuse, and dependence, yet the familial transmission of alcohol expectancies is not well understood. The purpose of this study was to examine the familial transmission of positive alcohol expectancies. Participants were 2,627 14- to 22-year-old female twins. Experiences shared by twins, rather than genetic factors, explained most of the familial similarity for positive alcohol expectancies, but an even larger proportion of the variation in positive alcohol expectancies was explained by nonfamilial factors. The extent to which the familial similarity for positive alcohol expectancies was moderated by age, race, drinking status, and the sharing of peer groups was also examined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)