特殊结构(带支柱)球罐整体无模成形工艺的实验研究

为了解决无模成形方法成形大型球罐的困难,此文提出了一种特殊结构的壳体,该壳体在胀形前已将支柱焊在球瓣上,并且针对赤道带瓣对接焊处成形困难问题提出了一种减少瓣间两面角的特殊工艺方法.此文针对这种壳体的无模成形技术进行了实验研究,并对应变分布、直径变化及柱脚在不同摩擦条件下位移进行了测量分析,指出了此种壳体的无模成形技术是可行的,并具有良好的经济性,为大型球罐的无模成形制造提供了技术依据.     

Computational fluid dynamics applied to water and wastewater treatment facility modeling

The major issues in water and wastewater industry are to meet quality requirements, to guarantee treatment process efficiency, to contain investment and operating costs. This implies the use of powerful predictive modeling and simulation tools which are able to account for the multiple interaction between all the water quality and process design parameters. Computational Fluid Dynamics modeling tools have already been widely used in other industries but their application in water industry is quite recent. This paper presents different applications of CFD modeling to the study of the hydro-dynamic and mass transfer performance of single- or two-phase flow reactors used in water and wastewater treatment. Numerical simulations, together with experimental measurements, have been performed on laboratory and full-scale plants in order to gain a better under-standing of the physical phenomena (mixing, interfacial transfer) occurring in these systems. Numerical simulations are systematically validated by experiments. The paper shows how CFD can be helpful in order to improve the design of existing water treatment plants and the process efficiency. In this scope, CFD enables designs more reliable and cost effective water treatment processes which remain basic environmental policy issues.     

Photodegradation of alpha-naphthaleneacetic acid in aqueous solution.

Kinetic processes of alpha-naphthaleneacetic acid (NAA) photolysis were studied under different conditions. The results showed that the ultraviolet light was more effective than fluorescent light in promoting degradation, and the degradation of NAA under ultraviolet light followed the first order kinetics with the photolysis rate constant of 1.15 x 10(-2) min-1 and half-life time (t1/2) of 60 min. Further, it was proved that the photolysis rate was higher in the presence of oxygen, titanium dioxide (TiO2), and low pH (acidic solution). At last, two photolysis intermediates were identified by GC-MS and possible photolysis pathways were proposed.     

Effect of fuel oil and dispersant on cell cycle and macromolecular synthesis in the chlorococcal alga Scenedesmus armatus

Growth and reproductive processes in synchronous cultures of the alga Scenedesmus armatus (isolated from Baltic phytoplankton) were followed in the presence of various concentrations of dispersant DP-105, oil, and mixtures of oil and dispersant. The inhibition of protoplast fission was the most prominent effect of oil. Nuclear division was inhibited to a lesser extent. With an increasing concentration of oil, dispersant, or a mixture of both, the inhibitory effects were expressed earlier. The presence of oil compounds did not effect the timing of DNA replication, but it did reduce the number of replication rounds in a concentration dependent manner. The inhibition of DNA synthesis was accompanied by slightly delayed cessation of RNA and protein synthesis. Starch synthesis was always inhibited to a lesser extent, and at a later time, than other macromolecular syntheses. Pigment synthesis continued almost to the end of the cell cycle. Thereafter, a rapid degradation of all pigments began and the cells became bleached. No inhibitory effect on reproductive processes was found if oil or dispersant were added to cultures transferred into darkness. Furthermore, recovery from inhibition of reproductive processes caused by oil in continuously illuminated cultures was observed in darkened cells. Chemically dispersed fuel oil was only slightly more toxic than mechanically dispersed fuel oil; an additive, rather than synergistic, effect of oil/dispersant mixture was found.     

A multivariate statistical analysis of the composition of rainwater near Cubatão, SP, Brazil

With the aim of estimating the chemical composition of bulk precipitation (wet + dry) in Cubat?o, rainwater samples were collected at several localities in the Cubat?o region from May 1984 to October 1985. The levels of some inorganic ions (Na+, Ca2+, K+, Mg2+, Cl-, SO4(2-), NH4+, PO4(3-)) were measured by atomic absorption spectrophotometry, turbidimetry and titration analysis. Correlation and Fisher discrimination indices, principal component and varimax loading and scores were determined in the multivariate statistical data treatment. The results showed that ionic concentrations in rainwater from Vila Parisi are significantly higher than those of Cubat?o Centro, Santos and Serra do Mar. The ionic compositions of the Vila Parisi rainwater seem to be mainly determined by local anthropogenic activities (industrial pollution). Besides the influence of this factor on water quality, there is also a natural oceanic contribution involving Cl- and Na+ at the other locations.     

Environmental change in Bashang region historical periods

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The dilemma of chromosomal mosaicism in chorionic villus sampling—‘direct’ versus long-term cultures

Chromosomal mosaicism is one of several unanswered dilemmas in first-trimester prenatal diagnosis. We report the course of a pregnancy in which a normal karyotype was detected on direct CVS preparation and fetal blood, 100 per cent trisomy 21 in one long-term CVS culture, and low-rate trisomy 21 mosaicism in a second long-term CVS culture and amniocentesis. The phenotypically normal infant had a 6 per cent mosaicism of trisomy 21. It appears that a persistent low-rate mosaicism in different tissues may be indicative of the true status of the fetus.     

The enhancement of photodegradation efficiency using Pt–TiO2 catalyst

This study investigates the mechanism of photosensitization and the recombination of excited electron–hole pairs affected by depositing platinum (Pt) on the surface of titanium dioxide (TiO₂). A new catalyst of Pt–TiO₂ was prepared by a photoreduction process. Being model reactions, the photocatalytic oxidation of methylene blue (MB) and methyl orange (MO) in aqueous solutions using the Pt–TiO₂ catalyst was carried out under either UV or visible light irradiation. The experimental results indicate that an optimal content of 0.75%Pt–TiO₂ achieves the best photocatalytic performance of MB and MO degradation and that the Pt–TiO₂ catalyst can be sensitized by visible light. The interaction of Pt and TiO₂ was investigated by means of UV–Vis absorption spectra, photoluminescence emission spectra, and X-ray photoelectron emission spectroscopy. The Pt⁰, Pt²⁺ and Pt⁴⁺ species existing on the surface of Pt–TiO₂, and the Ti³⁺ species existing in its lattice may form a defect energy level. The Pt impurities, including Pt, Pt(OH)₂, and PtO₂, and the defect energy level absorb visible light more efficiently in comparison with the pure TiO₂ and hinder the recombination rate of excited electron–hole pairs.     

The MMT bag for emission source sampling: design and evaluation

This paper presents the design and evaluation results for a metal-coated multilayer Tedlar (MMT) bag that was developed for the collection of source emissions. The applicability of the MMT bag was evaluated for a number of important greenhouse relevant gases: CO, CO2, CH4, N2O, and total hydrocarbons (THCs). The bag was tested for durability and stability for a range of concentrations of the tested compounds using both laboratory-prepared samples and real source samples. The results show that all tested compounds were more stable when stored in the MMT bag than when stored in a regular Tedlar bag. These compounds can be stored at room temperature for at least 3 months without significant changes in concentration. When properly packed, the MMT bag is durable and may be shipped by air. The MMT bag is lower in cost, lighter in weight, and easier to clean, and it requires less devices during the subsequent laboratory analysis compared with a stainless steel canister, which is often used to collect air and source samples.