The Effect of Non-Equilibrium Condensation on Supersonic Air Flows over Rectangular Cavities

Numerical simulations have been carried out for a supersonic two-dimensional flow over open,rectangular cavi-ties(length-to-depth ratios are L/D=1.0 and 3.0)in order to investigate the effect of non-equilibrium condensa-tion of moist air on supersonic internal flows around the cavity for the flow Mach number 1.83 at the cavity en-trance.In the present computational investigation,a condensing flow was produced by an expansion of moist airin a Laval nozzle.The computational results showed that the upstream traveling compression waves becomeweaker than those without the condensation.Consequently,the weaker compression waves cannot excite theshear layer strongly and amplitudes of oscillation in the cavity became smaller than those without the condensa-tion.The occurrence of the non-equilibrium condensation in case of L/D=1.0 affected strongly the amplitude andfrequency of oscillation in the cavity compared with L/D=3.0.     

Structural and surface energy analysis of nitrogenated ta-C films

Surface and bulk properties of the Filtered Cathodic Vacuum Arc prepared nitrogenated tetrahedral amorphous carbon (ta-C:N) films were characterized by X-ray Photoelectron Spectroscopy (XPS), Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), Raman spectroscopy, Atomic Force microscopy and contact angle techniques. An increase in the Nitrogen (N) content of the films is accompanied by a reduction in the sp³ fraction, confirmed via the deconvolution of the C 1 s XPS spectra. Critical Raman parameters such as peak position and peak width of the G band, defect ratio, I_D/I_G and skewness of the G line were analyzed as a function of N content. ToF-SIMS showed the variance of chemical composition with the increase in the sputtering depth. While some amount of incorporated oxygen and hydrogen were observed for all films; for high N content ta-C:N films signature of CN bonds was evident. Surface energies (both polar and dispersive components) for these ta-C:N films were analyzed in a geometric mean approach. Contact angle measurements using both deionized water and ethylene glycol reveal that upon the insertion of nitrogen into ta-C films, the initial change in the contact angle is sharp, followed by a gradual decrease with subsequent increase in N content. The variation of contact angle with increasing N content corresponds to an increase of the total surface energy with an increase of the polar component and a decrease of the dispersive component.     

Fabrication of and performance studies on a low cost solar cooker having an inclined aperture plane

A low cost box-type solar cooker made of two paper carton boxes with crumpled newspaper balls as insulation has been fabricated with a tilted aperture plane. Comparative tests of this cooker have been conducted against a normal type costlier solar cooker with 1000 ml load of water in each of the cookers. It has been observed that on a sunny day water temperature initially increases more rapidly in the new cooker compared to the normal type cooker. But at temperatures higher than 90°C both the cookers perform similarly. Two figures of merit F₁ and F₂ have also been found to be satisfactory. An arrangement of low cost auxiliary heating using a 100w electric bulb inside a blackened metal casing allows the carton box cooker to reach cooking temperatures under cloudy conditions with ease when the normal type solar cooker fails. The cost of materials for the new cooker is within US $10 and has been observed to be as effective as the normal type solar cooker which requires between US $40 and $65 to fabricate.     

Water Plasticization and Crystallization of Lactose in Spray-dried Lactose/Protein Mixtures

ABSTRACT: Water plasticization led to depression of the glass transition causing significant changes in the physico-chemical and crystallization properties in storage of lactose and lactose/protein (3:1) mixtures. Glass transition (Tg) and crystallization temperatures (Tcr) were determined using differential scanning calorimetry. Whey protein isolate (WPI), albumin, and gelatin increased the Tg of dry powders; when Na-caseinate was used, a decrease was observed. In the presence of proteins and water, a decrease of Tg at aw ≤ 0.23 was observed. At aw ≤ 0.33, proteins increased the Tg In the anhydrous state, Tcr decreased in the presence of proteins possibly because of browning. WPI, Na-caseinate, albumin, and gelatin delayed lactose crystallization in humidified samples, with albumin and gelatin delaying it more than WPI at all storage humidities. Temperature difference between an observed instant crystallization and glass transition (Tcr to Tg) was larger for humidified samples containing proteins than for lactose. Various proteins and water affect crystallization behavior of amorphous lactose differently in spray-dried powders. This should be considered in evaluating sugar crystallization properties in food products including dairy powders.     

Senescent fibroblasts as feeder cells for lymphoid cell cloning

In 1994, a magazine article, a newspaper article, and a segment of the television newsmagazine 60 Minutes presented information that cast doubt on the Centers for Disease Control and Prevention's conclusion that a dentist in Florida had infected six of his patients with the human immunodeficiency virus (HIV). These reports were based on previously unavailable documentary evidence, which suggested that the infected patients had unreported or undetected risk factors for HIV infection and that the molecular analyses used to determine that the dentist and his patients had the same strains of HIV had potentially serious flaws. A recent article in this journal sought to dismiss the relevance of this information in the eyes of the scientific community. That report, however, failed to respond directly to many key pieces of evidence, and it offered no rebuttal beyond personal invective and a reassertion of previously published material. Although scientists and clinicians should not rely solely on media reports when drawing conclusions about this complex and controversial case, they deserve a chance to consider and reflect on this material in a meaningful way.