Comparison of mass transfer efficiency in horizontal rotating packed beds and rotating biological contactors

In this study, the mass transfer efficiencies of a novel horizontal rotating packed (h‐RPB) bed and the conventional disc‐type rotating biological contactor (RBC) were studied at four speeds and seven submergences. Pall rings of two different sizes (25, 38 mm), superintalox saddles and a wiremesh spiral bundle were used as packings in the h‐RPB. Volumetric gas–liquid mass transfer coefficients were determined by unsteady state absorption of atmospheric oxygen in de‐aerated water. Power consumption per unit liquid volume has been found for all geometries tested. The oxygen transfer efficiency values for the h‐RPB were found to be 2–5 kg kWh^?1 and for the disc RBC were found to be 1–2 kg kWh^?1. The performance of the h‐RPB was also compared with other gas–liquid contactors such as surface aerators. The study proves that the h‐RPB is a energy efficient alternative to conventional contactors. Copyright © 2005 Society of Chemical Industry     

Wind flow patterns about buildings

A knowledge of building wake characteristics is useful in a variety of applications including dispersion of pollutants downwind of conventional or nuclear power plants, airport runway interference effect, take-off/landing limitations at heliports, pedestrian wind comfort, and wind loads on structures. Recent investigations have advanced both understanding of physical flow processes occurring in the near and far wake regions and theoretical predictive capability for flow and diffusion in the far wake region. These studies have shown, for example, that separation cavities immediately downwind are not enclosed by free streamlines as in two-dimensional separation/reattachment, that organized vortices can play an important role in wake development, and that theoretical solutions for some wake regions are possible.     

沉默的文化——妇女的住房和土地权利

我们即将对第四届妇女大会（北京）召开十年以来的妇女发展状况进行回顾，并且要对千年发展目标的执行情况进行中期评估。因此，我们有必要对那些影响妇女日常生活的关键问题进行审视并采取相应的行动，这些问题一直被各国政府和国际社会所忽视。     

Is my model any good: differentially private regression diagnostics

Linear and logistic regression are popular statistical techniques for analyzing multi-variate data. Typically, analysts do not simply posit a particular form of the regression model, estimate its parameters, and use the results for inference or prediction. Instead, they first use a variety of diagnostic techniques to assess how well the model fits the relationships in the data and how well it can be expected to predict outcomes for out-of-sample records, revising the model as necessary to improve fit and predictive power. In this article, we develop \(\epsilon \)-differentially private diagnostics tools for regression, beginning to fill a gap in privacy-preserving data analysis. Specifically, we create differentially private versions of residual plots for linear regression and of receiver operating characteristic (ROC) curves as well as binned residual plot for logistic regression. The residual plot and binned residual plot help determine whether or not the data satisfy the assumptions underlying the regression model, and the ROC curve is used to assess the predictive power of the logistic regression model. These diagnostics improve the usefulness of algorithms for computing differentially private regression output, which alone does not allow analysts to assess the quality of the posited model. Our empirical studies show that these algorithms can be effective tools for allowing users to evaluate the quality of their models.     

Dual Wide Band Circularly Polarized Microstrip Patch Antenna with Offset Feed

Wireless Personal Communications - A compact, dual band circularly polarized antenna has been proposed and investigated. It has been designed with single feed and has simple structure. The antenna...     

Photoactive Electrodes Incorporating Electrosprayed Bacterial Reaction Centers

Highly efficient light absorption and charge separation within the photosystem and reaction center (RC) complexes of photosynthetic plants and bacteria are of great interest for solar cell and photo detector applications, since they offer almost unity quantum yield and expected ultimate power conversion efficiencies of more than 18% and 12%, respectively. In addition, the charge separated states created by these protein complexes are very long lived compared to conventional semiconductor solar cells. In this work, a novel technique is presented for the deposition of photosynthetic protein complexes, by electrospraying RCs of Rhodobacter sphaeroides onto highly ordered pyrolytic graphite (HOPG) electrodes. Remarkably, it is shown that the RCs not only survive exposure to the high electric fields but also yield peak photocurrent densities of up to 7 μA cm^?2, which is equal to the highest value reported to date.     

Design theory and performance analysis of paraboloidal solar cooker

A paraboloidal collector having aperture diameter 1.3 m, depth 0.30 m, and focal length 0.35 m was designed and fabricated. The paraboloidal solar cooker was tested under no-load conditions at a recorded maximum temperature of 326°C. The analysis was made from the sensible heating and cooling curves. The values of the overall heat loss factor (F′ UL) obtained from the sensible cooling curve were smaller on different days. The minimal heat loss was due to the wind shield provided at the paraboloidal receiver. Analysis of the sensible heating curve gave the values of the optical efficiency factor (F′ η₀). The performance of the paraboloidal collector was determined, and the thermal efficiency was found to be 26%. The performance curve was plotted to predict the approximate time required to boil a known amount of water under given climatic conditions. The solar cooker was found to be useful in cooking a variety of foods.     

Heat insulation characteristics of high bulk nonwovens

The insulation layer is a vital component in cold weather clothing. Majority of the heat loss from the body is restricted by the insulation layer. Hence, the design of insulation layer is critical for the performance of extreme cold weather clothing. The factors which influence the thermal resistance of nonwovens’ layer are fibre denier, fibre cross-section and bulk density, porosity and thickness of nonwovens. In this study, we try to optimize these parameters for high-bulk thermal bonded nonwovens using solid and hollow polyester fibres of different deniers. The effect of these parameters and their interdependency has been evaluated by suitable statistical analysis with the help of Design expert software. Contribution analysis has been carried out to ascertain the importance of thickness, areal density and fibre denier and shape. Finer and hollow fibres give better thermal insulation than the coarser and solid fibres. Nonwovens have very high porosity, especially the lighter and thinner ones have poor thermal resistance. Finer and hollow fibres due to their superior thermal insulation are ideal choice for making thinner and lightweight extreme cold weather clothing.     

Starch Hydrolysate,an Optimal and Economical Source of Carbon for the Secretion of Citric Acid by Yarrowia lipolytica (DS-1)

Using Yarrowia lipolytica (DS-1), secretion of citric acid is studied as a function of carbon sources such as glucose, fructose, hydrol, sucrose, cane sugar molasses, kerosene (all available commercially) and tapioca starch hydrolysate, invert sucrose and invert cane sugar molasses (all prepared in laboratory). On the basis of their acceptability by DS-1 for citric and isocitric acid secretion, it is concluded that (a) sucrose and cane sugar molasses (with/without inversion) served as poor carbon sources, (b) fructose, hydrol, impure tapioca starch hydrolysate (96 DE w/w) and invert sucrose served as relatively better carbon sources and (c) purified tapioca starch hydrolysate (96 DE w/w) was the best carbon source to substitute glucose by giving comparable (75%) efficiency of conversion and economical advantage.     

Pathway and single gene analyses of inhibited Caco-2 differentiation by ascorbate-stabilized quercetin suggest enhancement of cellular processes associated with development of colon cancer

The aim was to investigate mechanisms contributing to quercetin's previously described effects on cell-proliferation and -differentiation, which contradicted its proposed anticarcinogenic potency. In a 10-day experiment, 40 microM quercetin stabilized by 1 mM ascorbate reduced Caco-2 differentiation up to 50% (p < 0.001). Caco-2 RNA from days 5 and 10, hybridized on HG-U133A2.0 Affymetrix GeneChips(R), showed 1,743 affected genes on both days (p < 0.01). All 14 Caco-2 differentiation-associated genes showed decreased expression (p < 0.01), including intestinal alkaline phosphatase, that was confirmed technically (qRT-PCR) and functionally (enzyme-activity). The 1,743 genes contributed to 27 pathways (p < 0.05) categorized under six gene ontology (GO) processes, including apoptosis and cell-cycle. Genes within these GO-processes showed fold changes that suggest increased cell-survival and -proliferation. Furthermore, quercetin down-regulated expression of genes involved in tumor-suppression and phase II metabolism, and up-regulated oncogenes. Gene expression changes mediated by ascorbate-stabilized quercetin were concordant with those occurring in human colorectal carcinogenesis ( approximately 80-90%), but were opposite to those previously described for Caco-2 cells exposed to quercetin without ascorbate ( approximately 75-90%). In conclusion, gene expression among Caco-2 cells exposed to ascorbate-stabilized quercetin showed mechanisms contrary to what is expected for a cancer-preventive agent. Whether this unexpected in vitro effect is relevant in vivo, remains to be elucidated.