Methyl methacrylate (MMA) and alumina recovery from waste artificial marble powder pyrolysis

Journal of Material Cycles and Waste Management - Owing to various advantages of artificial marble compared to natural marble, its application has been rising exponentially, which has resulted in...     

可张孔曝气器曝气能耗试验研究

通过试验研究，总结出可张孔曝气阻力损失的影响因素，以优化产品的结构设计参数，降低产品在工程应用中的能耗，获取更好的经济效益。     

Ammonia production and kinetic properties of glutamate dehydrogenase in the sipinculid Phascolosoma arcuatum exposed to anoxia

The amounts of total NH ₄ ⁺ detected in the external media in which Phascolosoma arcuatum had been exposed to various periods of anoxia were significantly greater than those in which the worms were exposed to normoxia for a similar period. The increased NH ₄ ⁺ production by P. arcuatum during anoxic exposure was unlikely to be due to an increased catabolism of adenine nucleotides or urea. In contrast, there were significant decreases in the concentrations of several free amino acids in the coelomic plasma and body tissues of individuals during the 48 h of anoxic exposure. The amount of NH ₄ ⁺ produced by the anoxic P. arcuatum could be accounted for by the decreases in the concentrations of aspartate or glycine. Increases in the catabolism of free amino acids (FAA), leading to the increased production of NH ₄ ⁺ , in P. arcuatum during anoxia were supported by the detection of significant changes in the kinetic properties of glutamate dehydrogenase (GDH), in the deaminating direction, from worms exposed to anoxia for 48 h. The apparent increase in the affinity of GDH from the anoxic worm to glutamate would bring about a greater deaminating activity at physiological concentrations of ths substrate. P. arcuatum used in these experiments were collected from the mangrove swamp at Mandai, Singapore between 1990 and 1993.     

Metabolic response under different salinity and temperature conditions for glass eel Anguilla japonica

Diadromous fish often enter freshwater directly from seawater via fish ladders or channels built in estuarine dams. The oxygen consumption rates (OCR) of glass eel, Anguilla japonica, were determined using an automatic intermittent flow respirometer under various salinity and temperature regimes to physiologically explain this direct movement. The endogenous rhythm of the OCR in wild glass eels, freshly collected from estuaries, was nearly synchronous with the tidal pattern at the estuarine collection site. When the salinity was changed from 20 psu (12°C) at a constant temperature to that of freshwater, the OCR of the glass eels decreased by 21.6±7.0% (mean ± SD) (P<0.05), showing a dampened rhythm for about 48 h. After this period of impediment, the glass eels resumed normal metabolic activity. Direct migration from seawater to freshwater under constant temperature would result in a severe physiological stress for these glass eels for about two days. When the glass eels were exposed to a cyclic change in water temperature of 2°C 26 h⁻¹, as they encounter in estuaries, and then were introduced to freshwater abruptly, the OCR rhythm corresponded to the cyclic changes in water temperature after exposure to freshwater. Under these conditions, the mean OCR of the glass eels had a small difference before and after exposure to freshwater. These data explained how glass eels can directly move from sea water into the freshwater without any apparent metabolic stress in the estuaries showing cyclic change in water temperature (Δt=2°C).     

Effects of calcination temperature on physicochemical property and activity of CuSO4/TiO2 ammonia-selective catalytic reduction catalysts

CuSO_4/TiO_2 catalysts with high catalytic activity and excellent resistant to SO_2 and H_2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH_3.The performance of catalysts is largely affected by calcination temperature.Here,effects of calcination temperature on physicochemical property and catalytic activity of CuSO_4/TiO_2 catalysts were investigated in depth.Catalyst samples calcined at different temperatures were prepared first and then physicochemical properties of the catalyst were characterized by N2 adsorption-desorption,X-ray diffraction,thermogravimetric analysis,Raman spectra,Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,temperature-pro grammed desorption of NH_3,temperature-programmed reduction of H_2 and in situ diffuse reflectance infrared Fourier transform spectroscopy.Results revealed that high calcination temperature had three main effects on the catalyst.First,sintering and anatase transform into rutile with increase of calcination temperature,causing a decrement of specific surface area.Second,decomposition of CuSO_4 under higher calcination temperature,resulting in disappears of Br(?)nsted acid sites(S-OH),which had an adverse effect on surface acidity.Third,CuO from the decomposition of CuSO_4 changed surface reducibility of the catalyst and favored the process of NH_3 oxidation to nitrogen oxides(NO_x).Thus,catalytic activity of the catalyst calcined under high temperatures(≥600℃) decreased largely.     

构树修复对重金属污染土壤环境质量的影响

通过温室盆栽试验,研究构树（Broussonetia papyrifera）生长对重金属污染土壤酶活性和微生物群落结构的影响.结果表明,构树修复污染土壤中酶活性和微生物多样性明显提高.经270d培养后,构树生长土壤中蔗糖酶和酸性磷酸酶活性与种植土壤相比分别显著（P<0.05）提高3.12倍和2.29倍;土壤脱氢酶与有效态As、Cd、Pb、Zn和Cu含量,蔗糖酶与有效态Cd含量,以及磷酸酶与有效态Cd和Cu含量之间呈显著负相关（P<0.05）.根据16S和18S rDNA PCR-DGGE分析表明,构树修复可提高污染土壤中细菌和丛枝菌根真菌多样性.上述结果表明,构树修复可有效改善重金属污染土壤的环境质量.然而,污染土壤中重金属有效态含量下降不明显,必须辅助物理和化学措施来强化构树对重金属污染土壤的生态修复潜力.     

Development of monitoring technology for airborne particulate matter

Particulate matter suspended in the air has adverse effects onhuman health. Its level of concentration is an important parameter in evaluating the degree of hazard it poses to the atmosphere. Conventional methods used in measuring particulatematter are often filter-based, which indicates some disadvantagesbecause such a base requires labor and time. In this study, to achieve real-time measurements, a new electrical method was developed for measuring PM10 and PM2.5 concentrations. The basicprinciple is to electrically charge particles passing through thePM inlet using a corona charger and measure the currents createdby charged particles to obtain the number concentration of particulate matter. A new type inlet based on the particle cupimpactor configuration was designed and its performance was evaluated. A unipolar diffusion charger was developed and thecharger's efficiency was determined experimentally in terms ofPn, which represents the penetration through the charger,P, times the average charge number acquired by a particle,n, for different particle sizes. The correlation was constructed between the PM10 (or the PM2.5) mass concentrationsand the electrical currents due to particles, which were chargedby the diffusion charger.     

Global and Regional Distribution of Carbon Monoxide from MOPITT: Seasonal Distribution at 700 hPa

The Measurement of Pollution in the Troposphere (MOPITT) instrument is an eight-channel gas correlation radiometer, which was launched on the Earth Observing System (EOS) Terra satellite in 1999. Carbon monoxide (CO) is one of the important trace gases because its concentration in the troposphere directly influences the concentrations of tropospheric hydroxyl (OH), which controls the lifetimes of tropospheric trace gases. CO traces the transport of global and regional pollutants from industrial activities and large scale biomass burning. The global and regional distributions of CO were analyzed using the MOPITT data for East Asia, which were compared with the ozone distributions. In general, seasonal CO variations are characterized by a peak in the spring, which decrease in the summer. This work also revealed that the seasonal cycles for CO are at a maximum in the spring and a minimum in the summer, with average concentrations ranging from 118 to 170 ppbv. The monthly average for CO shows a similar profile to that for O3. This fact clearly indicates that the high concentration of CO in the spring is possibly due to one of two causes: the photochemical production of CO in the troposphere, or the transport of the CO into East Asia. The seasonal cycles for CO and O3 in East Asia are extensively influenced by the seasonal exchanges of different air mass types due to the Asian monsoon. The continental air masses contain high concentrations of O3 and CO, due to the higher continental background concentrations, and sometimes to the contribution from regional pollution. In summer this transport pattern is reversed, where the Pacific marine air masses that prevail over Korea bring low concentrations of CO and O3, which tend to give the apparent summer minimums.     

Seasonal characteristics of haze observed by continuous visibility monitoring in the urban atmosphere of Kwangju, Korea

Continuous visibility monitoring has been carried out inKwangju, Korea since May 1999. The total light extinctioncoefficient b _ext measured by a transmissometer andreveals seasonal trends in urban visual air quality,especially under hazy conditions with a visual range of lessthan 15 km. Seasonal atmospheric visibility under lowrelative humidity during the winter was observed to be betterthan during any other seasons. Summertime visibility wasseverely degraded due to highly increased light scattering byhygroscopic particles under high humidity atmosphericconditions. Visibility during spring and fall was alsomoderate. However, yellow sand in spring caused the lowestvisibility conditions over the measurement area for a fewdays. With continuous monitoring using the transmissometer,the daily average seasonal visual range was measured to be13.1, 9.2, 11.0, and 13.9 km in spring, summer, falland winter, respectively. Under the atmospheric humiditycondition less than 60%, visual range was observed tobe 16.1, 13.9, 15.1, and 16.6 km in spring, summer,fall, and winter, respectively. The mean light extinctionbudget by sulfate and nitrate aerosols was determined to bethe highest value of 63.71% during the summer and thelowest value of 27.08% during spring. During the `yellow sand dust' period, a mean light extinction budget by soil particles was estimated to be at an unusually high value of 44.22%.