Organophosphate and phthalate esters in air and settled dust - a multi-location indoor study

This paper reports the abundance in indoor air and dust of eleven organophosphate esters and six phthalate esters. Both groups of these semi-volatile compounds are widely incorporated as additives into plastic materials used in the indoor environment, thus contributing to indoor exposure to industrial chemicals. Thirty sampling sites representing three different indoor environments (private homes, day care centers, and workplaces) in the Stockholm area, Sweden, were selected to obtain representative concentration profiles in both ambient air and settled dust. Eight of the target organophosphate esters and all six phthalate esters were found in both air and dust samples at all locations. The phthalate esters were more abundant than the organophosphate esters, typically ten times higher total concentrations. Especially interesting were the high levels of tributoxyethyl phosphate in the day care centers, the relatively high levels of chlorinated organophosphate esters in the air of workplaces and the overall high levels of diethylhexyl phthalate in dust. The air concentration profiles of the phosphate esters differed significantly between the three indoor environments, whereas the concentration profiles of the phthalate esters as well as their total concentrations were similar. The correlation between concentrations found in air and in dust was found to be weak. PRACTICAL IMPLICATIONS: Organophosphate esters and phthalate esters are commonly used as additives in numerous building materials and consumer products. The use of these compounds is increasing, and phosphate and phthalate esters are to be regarded as ubiquitous contaminants in the indoor environment. These compounds comprise a number of different compounds that have been associated with biologic effects in animal studies as well as in humans. Thus, it is of concern to increase the knowledge about human exposure of these compounds because of their presence in indoor air. In this paper, thirty indoor environments have been surveyed with respect to seventeen of the most abundant of these compounds.     

Disinfection of Legionella pneumophila by ultrasonic treatment with TiO2

An ultrasonic treatment system, using a TiO₂ photocatalyst, was used to disinfect Legionella pneumophila. A kinetic study of the process indicates that TiO₂ significantly improves the disinfection process. The concentrations of viable cells were reduced to 6% of the initial concentrations in the presence of 0.2 g/ml TiO₂ after a 30 min of treatment period, while only an 18% reduction was observed in the absence of TiO₂. The potency of the disinfection could be enhanced, to some extent, by increasing the amount of TiO₂ used. Cell concentrations were decreased by an order of 3 within 30 min of treatment in the presence of 1.0 g/ml TiO₂. The disinfection power in the presence of TiO₂ versus Al₂O₃ was also compared and the findings showed that TiO₂ induced a higher cell killing. No significant effect of initial cell concentration on the disinfection was found in the range of 10²-10⁷ CFU/ml after a 30 min of treatment period. The mechanism of cell killing was investigated by examining the effects of OH radical scavengers such as ascorbic acid, histidine and glutathione. The disinfection power was reduced in samples that contained these radical scavengers, thus indicating the importance of OH radicals.     

Photocatalytic degradation of methyl orange by TiO2-coated activated carbon and kinetic study

TiO2-coated activated carbon (AC) grain (TiO2/AC) was prepared through hydrolytic precipitation of TiO2 from Tetrabutylorthotitanate and following heat treatment. The TiO2/AC was characterized by BET, SEM, XRD and optical absorption spectroscopy. The samples were employed as catalysts for methyl orange photocatalytic oxidation degradation in aqueous suspension, used as probe reaction. The kinetics of methyl orange photodegradation was analyzed. The results indicate that BET surface area of TiO2-coated ACs decreased drastically in comparison with the original AC with increasing TiO2 coatings by more than 1 doped cycle. Nano-TiO2 particles were dispersed on the AC with the size of 20-40 nm. Crystalline TiO2 doped onto AC was from anatase to rutile with increase of heat-treatment temperature. The TiO2/AC was shown high photoactivity for the photodegradation of methyl orange (MO) dyestuff in aqueous solution under UV irradiation. The kinetics of photocatalytic MO dyestuff degradation was found to follow a pseudo-first-order rate law. It was observed that the presence of the AC enhanced the photoefficiency of the titanium dioxide catalyst. Different amount of TiO2 coatings induced different increases in the apparent first-order rate constant of the process. The kinetic behavior could be described in terms of a modified Langmuir-Hinshelwood model. The values of the adsorption equilibrium constants for the organic molecules, KC, and for the rate constants, kc, were certainly dependent on TiO2 content. At 47wt% TiO2 coatings with the highest rate constant, the KC and kc was 0.1116l mmol(-1) and 0.1872 mmol l(-1) min(-1), respectively. The mechanism of methyl orange degradation was discussed in terms of the titanium dioxide photosensitization by the AC.     

药筒射击时出现卡壳原因分析及测试方法

为判断火炮射击时出现卡壳现象的原因是药筒问题还是火炮问题,对卡壳原因进行分析,并对其测试方法进行研究。具体的测试方法为：先根据应变片测得电流大小,计算出抽壳力。当遇到卡壳时,再测出卡壳力的大小,将卡壳力的大小与火炮实际抽壳力的大小相比较,如卡壳力小于火炮抽壳力,则说明出现卡壳现象是火炮抽壳故障所致;反之,说明卡壳原因是因为药筒卡壳力过大所致。结果显示,该方法简单易行、操作可靠、数据准确,有重要的理论和使用价值。     

利用原料1生产金属化阳极板试验研究

本文介绍了利用原料1在合金硫化炉进行金属化阳极板试验的过程。通过在合金硫化炉中进行原料1硫化、吹炼等试验过程,达到提镍降硫的目的。并在试验过程中摸索出了生产金属化阳极板的关键参数,同时对金属化阳极板中化学成分、镍直收率、钴直收率等关键指标进行了分析,为金属化阳极板的工业化生产提供了理论依据。     

Norovirus and MS2 inactivation kinetics of UV-A and UV-B with and without TiO2

Germicidal ultraviolet, such as 254-nm UV-C, is a common method of disinfection of pathogenic enteric viruses. However, the disinfection efficacies of UV-A or -B in terms of inactivating waterborne viruses such as norovirus have not been characterized. We evaluated the inactivation kinetics of MS2 bacteriophage and murine norovirus (MNV), a surrogate of human norovirus (NoV), by UV-A and -B. In addition to UV disinfection, we further investigated whether the presence of TiO₂ could enhance the virus inactivation kinetics of UV-A and -B. Both MS2 and MNV were highly resistant to UV-A. However, the addition of TiO₂ enhanced the efficacy of UV-A for inactivating these viruses. UV-A dose of 1379 mJ/cm² resulted in a 4 log₁₀ reduction. In comparison, UV-B alone effectively inactivated both MS2 and MNV, as evidenced by the 4 log₁₀ reduction by 367 mJ/cm² of UV-B. The addition of TiO₂ increased the inactivation of MS2; however, it did not significantly increase the efficacy of UV-B disinfection for inactivating MNV. When these treatments were applied to field water such as groundwater, the results were generally consistent with the laboratory findings. Our results clearly indicated that UV-B is useful for the disinfection of waterborne norovirus. However, MNV was quite resistant to UV-A, and UV-A effectively inactivated the tested viruses only when used in combination with TiO₂.     

Bacterial inactivation in water,DNA strand breaking,and membrane damage induced by ultraviolet-assisted titanium dioxide photocatalysis

The effects of UV-assisted TiO₂-photocatalytic oxidation (PCO) inactivation of pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium) in a liquid culture using different domains of UV irradiation (A, B and C) were evaluated. Structural changes in super-coiled plasmid DNA (pUC19) and genomic DNA of E. coli were observed using gel electrophoresis to demonstrate the photodynamic DNA strand breaking activity of UV-assisted TiO₂-PCO. Membrane damage in bacterial cells was observed using both a scanning electron microscope (SEM) and a confocal laser scanning microscope (CLSM). Both UVC-TiO₂-PCO and UVC alone resulted in an earlier bactericidal phase (initial counts of approximately 6 log CFU/mL) in 60 s and 90 s, respectively, in liquid culture. UVC-TiO₂-PCO treatment for 6 min converted all plasmid DNA to the linear form; however, under UVC irradiation alone, super-coiled DNA remained. Prolonged UVC-TiO₂-PCO treatment resulted in structural changes in genomic DNA from E. coli. SEM observations revealed that bacteria suffered severe visible cell damage after UVC-TiO₂-PCO treatment for 30–60 min. S. typhimurium cells showed visible damage after 30 min, which was confirmed using CLSM. All treated cells were stained red using propidium iodide under a fluorescent light.     

Mechanical and Tribological Properties of Ca/P-Doped Titanium Dioxide Layer Produced by Plasma Electrolytic Oxidation: Effects of Applied Voltage and Heat Treatment

Plasma electrolytic oxidation (PEO) is a technique that produces a hard oxide layer on the titanium surface where its properties can be tailored by changing the process parameters or by a posterior heat treatment (HT). In this work, a TiO₂ layer with different crystallinity was produced by PEO with different applied voltages (250 to 400 V) and post-HT at 600°C. Our aim was to evaluate the influence of the PEO voltage and HT on the mechanical and tribological properties of anodized Ti. There is an increase in pore size, oxide thickness, and Ca/P ratio for the oxide layer with the applied voltage during the PEO process. X-ray diffraction (XRD) results indicated an increase in the crystalline rutile phase in the oxide layer with voltage and HT. Nanoindentation shows an increase in the oxide hardness and elastic modulus with increased voltage and HT, leading to an improvement in the wear resistance.     

TC4钛合金引信天线零件精密加工研究

TC4钛合金引信天线上零件有腰型槽尺寸小、精度高、机械加工性能差等特点。通过多因素正交实验方法和多元线性逐步回归分析建立0.4mm超小刀具TC4钛合金切削力数学模型,分析了各切削参数对切削力的影响程度。通过该数学模型和实际生产经验优化了切削参数。通过MasterCAM软件对刀路轨迹进行优化、模拟和仿真。     

2002年钛年评

对2002年我国钛行业进行了调研,统计分析了2002年我国钛行业的生产与市场需求情况,对所取得成就进行了评述,并展望了钛的未来市场需求和行业发展趋势。