Antioxidant Capacity and Phenolic Content of the Aqueous Extract of Commonly Consumed Cucurbits

The antioxidant capacity of commonly consumed cucurbits vegetable was determined by the DPPH, FRAP, Fe³⁺ reducing power, and hydrogen peroxide scavenging assay. The aqueous extract of Luffa cylindrica showed the highest value of phenolic content and antioxidant capacity based on FRAP, Fe³⁺ reducing power, and hydrogen peroxide scavenging assay. However, Laginaria siceraria extract showed the highest flavonoid and DPPH scavenging activities among all three cucurbits used in this study. Phenolic content in aqueous extracts of Luffa cylindrica and Laginaria siceraria was almost equal. Cucurbita maxima exhibited the lowest phenolic, flavonoid content, and exhibited the lowest power of antioxidant scavenging. The antioxidant capacity of cucurbits was significantly correlated (P < 0.05) with the phenolic content of their extracts. The antioxidant capacity of Luffa cylindrica and Laginaria siceraria have also shown a significant correlation (P < 0.05).     

Sulfonated Reduced Graphene Oxide (RGO-SO3H): As an Efficient Nanocatalyst for One-Pot Synthesis of 2-Amino-3-cyano-7-hydroxy-4H-chromenes Derivatives in Water

Sulfonated reduced graphene oxide (RGO-SO₃H) was found to be an efficient catalyst for one-pot synthesis of a class of 2-amino-3-cyano-7-hydroxy-4H-chromenes derivatives using multicomponent reaction (MCR) of phenols, aldehydes and malononitrile under mild and green conditions. The reaction was performed in water as a green solvent and range of 2-amino-3-cyano-7-hydroxy-4H-chromenes were obtained in good to excellent yields. The RGO-SO₃H was reusable at least 5 times without significant decrease in its catalytic activity.     

Evaluation of calculational and material models for concrete containment structures

A computer code utilizing an appropriate finite element, material and constitutive model has been under development as a part of a comprehensive effort by the Electric Power Research Institute (EPRI) to develop and validate a realistic methodology for the ultimate load analysis of concrete containment structures. A preliminary evaluation of the reinforced and prestressed concrete modeling capabilities recently implemented in the ABAQUS-EPGEN code has been completed. This effort focuses on using a state-of-the-art calculational model to predict the behavior of large-scale reinforced concrete slabs tested under uniaxial and biaxial tension to simulate the wall of a typical concrete containment structure under internal pressure. This paper gives comparisons between calculations and experimental measurements for a uniaxially-loaded specimen. The calculated strains compare well with the measued strains in the reinforcing steel; however, the calculations gave diffused cracking patterns that do not agree with the discrete cracking observed in the experiments. Recommendations for improvement of the calculational models are given.     

In vitro expression and inhibition of procoagulant activity produced by bovine alveolar macrophages and peripheral blood cells

Local and systemic activation of coagulation is frequently associated with bacterial sepsis. The coagulopathy is due, at least in part, to expression of tissue factor (TF) by monocytes and macrophages. The purpose of this study was to evaluate the expression of procoagulant activity by bovine alveolar macrophages, leukocytes and platelets, and to determine the relative potency of three chemical inhibitors of TF expression (pentoxifylline, retinoic acid, and cyclosporin A). Bovine alveolar macrophages were stimulated with lipopolysaccharide (LPS) derived from Pasteurella haemolytica or recombinant bovine tumour nervous factor (TNF) and dose- and time-dependent effects on TF expression were studied. LPS and TNF induced TF expression in alveolar macrophages and LPS treatment of whole blood induced TF expression in mononuclear cells. Neutrophils and platelets also expressed procoagulant activity, but this activity was not inhibited by anti-bovine TF monoclonal antibody. Pentoxifylline (40 mumol/L), retinoic acid (0.01 mmol/L) and cyclosporin A (0.08 mumol/L) inhibited TF expression when added concurrently with LPS or TNF, but not when added 4 h after stimulation. TF mRNA was not detected in unstimulated alveolar macrophages by Northern blot analysis. In contrast, exposure to LPS or TNF for 6 h induced marked expression of TF mRNA, which was inhibited by treatment with pentoxifylline, retinoic acid and cyclosporin A. Expression of TNF by alveolar macrophages stimulated with LPS was also inhibited by these compounds. Our results indicate that procoagulant activity expressed by alveolar macrophages and monocytes is associated with expression of TF, whereas procoagulant activity expressed by neutrophils and platelets is not. The concentrations of pentoxifylline and retinoic acid necessary for inhibition of TF expression in vitro may not be achievable in vivo owing to their toxic effects. However, the in vitro concentration of cyclosporin A that inhibited TF expression did not exceed the plasma concentration observed in humans, and therefore may be useful for inhibition of TF expression in vivo.     

EFFECT OF MASS FLUX AND SYSTEM PRESSURE ON TWO-PHASE FRICTION MULTIPLIER

A horizontal boiling water loop was used to obtain pressure drop and heat transfer data for two-phase steam-water flow for pressures of up to 825 kPa. The data were used to examine the predictions of the separated flow model using the Lockhart-Martinelli method of estimating the two-phase friction multiplier.

The influence of mass flux on the two-phase friction multiplier has been reported for high pressure systems by many workers. The present work confirms the existence of this influence at low pressures as well. System pressure is also found to be a parameter. A correlation for the two-phase friction multiplier, incorporating the effects of mass flux and pressure, is presented here. The correlation has been tested against data from two independent sources. The predictions have been found to be in very good agreement with the data.     

Reliability of fat-pad sign in radial head/neck fractures of the elbow

In a prospective study at a single centre between August 1995 and March 1996, 193 patients with elbow injuries were studied. Standard radiographs of the elbows were taken. A total of 181 X-rays were reported by one person concerning the presence or absence of fractures and fat-pad signs. The radiographs were analysed and positive predictive values were calculated for the presence of the fat-pad sign with radial head/neck fractures. The sensitivity for radial head/neck fracture is 85.4 per cent, while the specificity is only 50 per cent. The fat-pad sign must be used cautiously as an indicator of radial head/neck fractures; its absence is a more reliable indicator of the absence of a radial head/ neck fracture.     

Tempering characteristics of a vanadium containing dual phase steel

Dual phase steels are characterized by a microstructure consisting of ferrite, martensite, retained austenite, and/or lower bainite. This microstructure can be altered by tempering with accompanying changes in mechanical properties. This paper examines such changes produced in a vanadium bearing dual phase steel upon tempering below 500 °C. The steel mechanical properties were minimally affected on tempering below 200 °C; however, a simultaneous reduction in uniform elongation and tensile strength occurred upon tempering above 400 °C. The large amount of retained austenite (≅10 vol pct) observed in the as-received steel was found to be essentially stable to tempering below 300 °C. On tempering above 400 °C, most of the retained austenite decomposed to either upper bainite (at 400 °C) or a mixture of upper bainite and ferrite-carbide aggregate formed by an interphase precipitation mechanism (at 500 °C). In addition, tempering at 400 °C led to fine precipitation in the retained ferrite. The observed mechanical properties were correlated with these microstructural changes. It was concluded that the observed decrease in uniform elongation upon tempering above 400 °C is primarily the consequence of the decomposition of retained austenite and the resulting loss of transformation induced plasticity (TRIP) as a contributing mechanism to the strain hardening of the steel. B. V. N. RAO, formerly Senior Research Engineer, Analytical Chemistry Department, General Motors Research Laboratories     

Development and applications of a compact hybrid tabletop terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser for x-ray lasing and harmonic generation

A hybrid tabletop (2 m x 3 m) terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser (1054 nm, 475 fs, 500 mJ, 9 x 10(17) W cm(-2)) has been developed for laser-matter experiments. An overall gain factor of 10(10) was achieved for the laser. The results of laser applications in the studies of soft-x-ray Ni-like Mo 18.9-nm lasing and of harmonic generation from solid surfaces are presented.