Human stress protein hsp70: overexpression in E coli, purification and characterization

The gene encoding the stress-inducible member of human heat shock protein hsp70, was expressed in E. coli using the bacteriophage T7 RNA polymerase-based gene expression system. Recombinant hsp70 (R-hsp70) was purified from inclusion bodies after solubilization and refolding, using a combination of ATP-agarose affinity chromatography and ion-exchange chromatography. R-hsp70 was shown to be monomeric and free of its structurally similar E. coli counterpart, DnaK. In addition, R-hsp70 is functional as demonstrated by its ability to bind to peptides and to ATP. The availability of pure, correctly folded R-hsp70 in sufficient quantity will assist in the structural and functional characterization of hsp70. Furthermore, an understanding of the cytoprotective function of hsp70 and its role in immune responses during infections will be facilitated by the availability of pure R-hsp70.     

Correlates of household smoking bans among Chinese Americans.

No population-based data are available on the degree to which Chinese Americans have adopted smoke-free household policies and whether these policies are effective in reducing environmental tobacco smoke (ETS) exposure. The present study examines the prevalence of smoke-free home rules among Chinese Americans living in New York City, describes predictors of adopting full smoking bans in the home, and explores the association between household smoking restrictions and ETS exposure at home. In-person interviews using a comprehensive household-based survey were conducted with 2,537 adults aged 18-74 years. Interviews were conducted in Mandarin, Cantonese, and other Chinese dialects. A total of 66% of respondents reported that smoking was not allowed inside the home, 22% reported a partial ban on smoking in the home, and 12% reported no smoking ban. Among current smokers, 38% reported a full household smoking ban. Current smoking status was the strongest predictor of less restrictive household smoking policies. Knowledge of the dangers of ETS, support of smoke-free air legislation, years in the United States, gender, income, and marital status also were associated with household smoking bans. Those living with a total household smoking ban were significantly less likely to report 30-day exposure to ETS than were those living in homes with a partial ban or no ban (7% vs. 68% and 73%, respectively). In homes of smokers and nonsmokers alike, exposure to ETS remains high. Smoke-free home rules and interventions among smokers and nonsmokers to raise awareness of the dangers of ETS have the potential to significantly reduce exposure to household ETS among this immigrant population.     

Delay-on-Demand: A Signaling Protocol to Reduce Blocking Probability in Optical Burst-Switching Networks

Optical burst switching (OBS) is emerging as one promising switching paradigm for the next generation optical networks. To support multiple services in burst-switching networks, the OBS paradigm should support some quality-of-service (QoS) provisioning. A major design issue in such networks is to reduce the blocking probability of the bursts arising due to resource contention at the intermediate core router. In this paper, we propose a signaling protocol which we call ‘Delay-on-Demand’ (OBS-DoD), to reduce blocking probability and support QoS in optical burst-switching networks. The proposed scheme guarantees that at least one of the bursts succeeds depending on its priority, propagation delay from the ingress router, and the burst-size when contention occurs at the core router. For this, we use a control packet to delay, in case of a contention, the transmission of bursts at the ingress router. We compare the performance of our proposal, by simulation, with an earlier proposed scheme, and show that the proposed OBS-DoD outperforms the earlier scheme in reducing the blocking probability. For simulation, we generated bursty traffic using an M/Pareto distribution.     

Simulation of reversible nylon-66 polymerization in homogeneous continuous-flow stirred tank reactors

Experimental data of Ogata¹ has been curve-fitted to obtain the forward and reverse rate constants for nylon-66 polymerization. Its molecular weight distribution (MWD) has been simulated in homogeneous continuous-flow stirred tank reactors (HCSTR) for 11 h of residence time when the reaction mass is very close to equilibrium. The set of algebraic equations have been solved using Brown's algorithm,² which was found to be more efficient compared to the Gauss-Jordon techniques of solution. The MWD thus obtained is compared with our earlier simulation of the molecular weight distribution from batch reactors³ and was found to differ significantly. In HCSTR, the weight fraction distribution does not undergo a maximum and the polydispersity index ρ of the polymer formed is much higher than that obtained from batch reactors. The number and weight average of the polymer formed in HCSTR is found to be significantly lower.     

Collector junction modeling of planar transistors

This work obtains a correlation between the physical structure and capacitance characteristics of collector junctions of planar bipolar epitaxial transistors. It uses an exponential model to represent the impurity distribution and makes available by non-destructive techniques base impurity profile constant, background concentration and collector junction depth from terminal measurements. The methods take care of such aspects of device geometry which are particular to small area high frequency transistors. Procedures are proposed for systematic evaluation of stray and sidewall capacitances. The latter can be used to monitor junction depth. Of interest for quick estimation of parameters is a method that utilises derivatives of the C(V) plot and does not require evaluation of strays.     

Low voltage current mirrors with enhanced bandwidth

This paper presents an improved low voltage cascode and flipped voltage follower (FVF) based current mirror with the enhancement of the bandwidth obtained by using a compensation resistor between the gates of the primary transistor pair. In this technique a carefully determined resistance is used in the diode connected MOS transistor of the current mirror for enhancing the bandwidth. Active realization of the compensation resistance using MOS operating in the triode region has also been applied to both the cascode and FVF based current mirror circuits. The proposed circuits have been simulated using PSpice for 0.25 μm CMOS technology and the obtained results are compared with their uncompensated topologies to show their effectiveness.     

Nonmeat Protein Alternatives as Meat Extenders and Meat Analogs

Abstract: The direct consumption of vegetable proteins in food products has been increasing over the years because of animal diseases, global shortage of animal protein, strong demand for wholesome and religious (halal) food, and economic reasons. The increasing importance of legume and oilseed proteins in the manufacturing of various functional food products is due to their high‐protein contents. However, the greatest obstacle to utilizing these legumes and oilseeds is the presence of antinutrients; but these antinutrients can be successfully removed or inactivated by employing certain processing methods. In contrast, the potential negative impact of the antinutrients is partially balanced by the fact that they may have a health‐promoting role. Legumes and oilseeds provide well‐balanced amino acid profiles when consumed with cereals. Soybean proteins, wheat gluten, cottonseed proteins, and other plant proteins have been used for texturization. Texturized vegetable proteins can extend meat products while providing an economical, functional, and high‐protein food ingredient or can be consumed directly as a meat analog. Meat analogs are successful because of their healthy image (cholesterol free), meat‐like texture, and low cost. Mycoprotein is fungal in origin and is used as a high‐protein, low‐fat, health‐promoting food ingredient. Mycoprotein has a good taste and texture. Texturized vegetable proteins and a number of mycoprotein products are accepted as halal foods. This article summarizes information regarding the molecular, nutritional, and functional properties of alternative protein sources to meat and presents current knowledge to encourage further research to optimize the beneficial effects of alternative protein sources.     

Determination of Mineral Composition and Heavy Metal Content of Some Nutraceutically Valued Plant Products

Minerals and heavy metal concentrations of 23 plants (arial parts, leaves, bark, stem, root, rhizome, dried berries, seeds) possessing health-promoting effects and used in indigenous medicines (as medicinal food) were determined using inductively coupled plasma atomic spectrometry. Vital essential minerals and heavy metals were present in all the samples analyzed. The majority of the plant materials were rich in some of the essential minerals like Na, K, Ca, Fe, Mg, Cu, Mn, and Zn, which are known to be beneficial for health. The plant material of Vitiveria zizinalis had highest concentration of toxic heavy metals, including arsenic (53.1 mg/100 g), chromium (6.74 mg/100 g), cobalt (10.2 mg/100 g), mercury (3.6 mg/100 g), and nickel (3.28 mg/100 g). Results of the present study provide vital data on the availability of some essential minerals, which can be useful to provide dietary information for designing value-added foods and for food biofortification. Apart from this, data on the contaminant levels of heavy metals highlights the necessity on the quality and safety concerns about their use.     

Induction of chemical and moisture resistance in Saccharum spontaneum L fiber through graft copolymerization with methyl methacrylate and study of morphological changes

In this article, morphological modification of Saccharum spontaneum L, a natural fiber through graft copolymerization with methylmethacrylate using ferrous ammonium sulfate—potassium per sulfate redox initiator has been reported. Different reaction parameters such as reaction temperature, time, initiator molar ratio, monomer concentration, pH and solvent were optimized to get maximum graft yield (144%). The graft copolymers thus formed were characterized by Fourier transform infrared, scanning electron microscopy, X‐ray diffraction and thermogravimetric, differential thermal analysis, and differential thermogravimetric techniques. Graft copolymer has been found to be more moisture resistant and also showed higher chemical and thermal resistance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009