石墨相氮化碳协同UV-H_2O_2光催化降解亚甲基蓝

以三聚氰胺为前驱体,经热解—回流法制备了石墨相氮化碳(g-C3N4),采用XRD、FTIR、SEM、EDS、PL等技术对g-C_3N_4进行了表征。研究了g-C_3N_4在UV-H_2O_2体系中对废水中亚甲基蓝(MB)的光降解效果。实验结果表明,UV+g-C_3N_4催化剂+H_2O_2体系能协同降解MB,在初始MB质量浓度为20 mg/L、初始废水p H为5、废水体积为250 mL、g-C_3N_4加入量为0.10 g、H_2O_2浓度为0.4 mmol/L、反应温度为25℃的优化工艺条件下,紫外光照射70 min时MB脱色率达98.32%。g-C_3N_4催化剂具有较好的重复使用性能,使用5次后MB脱色率仍保持在95.10%。     

Effects of Coastal Lighting on Foraging Behaviorof Beach Mice

Abstract:  Introduction of artificial light into wildlife habitat represents a rapidly expanding form of human encroachment, particularly in coastal systems. Light pollution alters the behavior of sea turtles during nesting; therefore, long-wavelength lights—low-pressure sodium vapor and bug lights—that minimize impacts on turtles are required for beach lighting in Florida (U.S.A.). We investigated the effects of these two kinds of lights on the foraging behavior of Santa Rosa beach mice (  Peromyscus polionotus leucocephalus ). We compared patch use and giving-up densities of mice for experimental food patches established along a gradient of artificial light in the field. Mice exploited fewer food patches near both types of artificial light than in areas with little light and harvested fewer seeds within patches near bug lights. Our results show that artificial light affects the behavior of terrestrial species in coastal areas and that light pollution deserves greater consideration in conservation planning.     

Metals in vineyard soils of the Penedès area (NE Spain) after compost application

The application of organic wastes to improve soil physical characteristics in mechanized vineyards planted after land levelling is becoming a common practice in Mediterranean areas. It may be useful as an additional source of organic matter and nutrients, but these wastes could also have negative effects due to their metal content. The aim of the study was to evaluate the influence of compost application on soil metal contents in mechanized vineyard soils of the Spanish Mediterranean area, where this practice is repeated every three years. The study was carried out in a ten-year-old vineyard where the main soil type is Typic Calcixerept. Composted cattle manure was applied in alternate rows, at a rate of 40 Mgha(-1) dry-weight. Nine sampling points were located along the slopes of two plots: a levelled plot prepared for mechanization with large soil disturbance movements within the plot, and a plot of undisturbed soil. At each location, soil samples were taken in both treated and untreated soils. Total concentrations (digestion with aqua regia) and the extractable DTPA (Diethylene-triaminepentacetic)-CaCl2-TEA (Triethanolamine) fractions of Cu, Zn and Mn were analyzed in each sample. For Cu and Zn, the initial concentration was higher in the undisturbed plot. In both cases, total Cu and total Zn were positively affected by manure input and the concentration in treated soils was significantly higher than in untreated soil. For Mn, the initial concentration was higher in disturbed soils than in undisturbed ones, and although in both scenarios the concentrations increased with manure, no significant differences were found between treated and untreated soils. The extractable fraction also increased in treated versus untreated soils, although for Cu and Mn the extractable/total metal ratio was similar in treated and untreated soils. After one compost application, total metal contents increased significantly, particularly for Zn. Most of those metals are accumulated in the soil, due to the soil characteristics.     

Cytotoxicity of the soluble and insoluble fractions of atmospheric fine particulate matter

Inhaled atmospheric fine particulate matter(PM_(2.5)) includes soluble and insoluble fractions,and each fraction can interact with cells and cause adverse effects.PM_(2.5) samples were collected in Jinan,China,and the soluble and insoluble fractions were separated.According to physiochemical characterization,the soluble fraction mainly contains watersoluble ions and organic acids,and the insoluble fraction mainly contains kaolinite,calcium carbonate and some organic carbon.The interaction between PM_(2.5) and model cell membranes was examined with a quartz crystal microbalance with dissipation(QCM-D) to quantify PM_(2.5) attachment on membranes and membrane disruption.The cytotoxicity of the total PM_(2.5) and the soluble and insoluble fractions,was investigated.Negatively charged PM_(2.5) can adhere to the positively charged membranes and disrupt them.PM_(2.5)also adheres to negatively charged membranes but does not cause membrane rupture.Therefore,electrostatic repulsion does not prevent PM_(2.5) attachment,but electrostatic attraction induces remarkable membrane rupture.The human lung epithelial cell line A549 was used for cytotoxicity assessment.The detected membrane leakage,cellular swelling and blebbing indicated a cell necrosis process.Moreover,the insoluble PM_(2.5) fraction caused a higher cell mortality and more serious cell membrane damage than the soluble fraction.The levels of reactive oxygen species(ROS) enhanced by the two fractions were not significantly different.The findings provide more information to better understand the mechanism of PM_(2.5) cytotoxicity and the effect of PM_(2.5) solubility on cytotoxicity.     

轻质高强多功能点阵夹层结构研究进展

根据材料类型和点阵结构,对点阵夹层结构进行了分类简述,并从静态、动态力学性能上,分析了各类点阵夹层结构的优缺点。简要叙述了设计过程中,综合考虑材料、结构以及功能等影响因素,针对不同使用工况的要求,可对各影响因素进行匹配设计,以实现传热特性、电磁波屏蔽特性、声学特性等不同的功能性需求。然后介绍了复合点阵夹层结构(嵌锁组装、模具热压成形、穿插编织)和金属点阵夹层结构(冲压成形、挤压线切割、拉伸网折叠、搭接拼装、熔模铸造以及增材制造)的主要制造工艺。最后提出如何将设计因子与多目标进行匹配及优化设计,是轻质高强点阵夹层结构的重点研究方向,轻质高强点阵夹层结构将朝多材料及多结构复合方向发展,开发新的制造工艺,提高费效比,是点阵夹层结构材料需解决的问题。     

Mesoporous WO3-graphene photocatalyst for photocatalytic degradation of Methylene Blue dye under visible light illumination

Advanced oxidation technologies are a friendly environmental approach for the remediation of industrial wastewaters. Here, one pot synthesis of mesoporous WO_3 and WO_3-graphene oxide(GO) nanocomposites has been performed through the sol–gel method. Then, platinum(Pt) nanoparticles were deposited onto the WO_3 and WO_3-GO nanocomposite through photochemical reduction to produce mesoporous Pt/WO_3 and Pt/WO_3-GO nanocomposites. X-ray diffraction(XRD) findings exhibit a formation of monoclinic and triclinic WO_3 phases. Transmission Electron Microscope(TEM) images of Pt/WO_3-GO nanocomposites exhibited that WO_3 nanoparticles are obviously agglomerated and the particle sizes of Pt and WO_3 are ~ 10 nm and 20–50 nm, respectively. The mesoporous Pt/WO_3 and Pt/WO_3-GO nanocomposites were assessed for photocatalytic degradation of Methylene Blue(MB) as a probe molecule under visible light illumination.The findings showed that mesoporous Pt/WO_3, WO_3-GO and Pt/WO_3-GO nanocomposites exhibited much higher photocatalytic efficiencies than the pure WO_3. The photodegradation rates by mesoporous Pt/WO_3-GO nanocomposites are 3, 2 and 1.15 times greater than those by mesoporous WO_3, WO_3-GO, and Pt/WO_3, respectively. The key factors of the enhanced photocatalytic performance of Pt/WO_3-GO nanocomposites could be explained by the highly freedom electron transfer through the synergetic effect between WO_3 and GO sheets, in addition to the Pt nanoparticles that act as active sites for O2 reduction, which suppresses the electron hole pair recombination in the Pt/WO_3-GO nanocomposites.     

Photocatalytic degradation of phenol

In this study photocatalytic degradation of phenol in thepresence of UV irradiated TiO₂ catalyst andH₂O₂was investigated. Effects of TiO₂ andH₂O₂concentrations and pH on photocatalytic degradation were examined. The rate constants for photocatalytic degradation wereevaluated as a function of TiO₂ and H₂O₂ concentrations and pH of the solution. It was found thatphotodegradation is an effective method for the removal of phenoland disappearance of phenol obeyed first order kinetics. The amount of CO₂h produced during photocatalytic degradation wascorresponding to the complete mineralization. Photodegradationcan be an alternative method for the treatment of phenol containing wastewaters.     

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%.     

Toxicity of Water-Soluble Fractions of Four Fuels for Metamysidopsis insularis, an Indigenous Tropical Mysid Species

The toxicity of the water-soluble fraction (WSF) of four fuels (leaded gasoline, unleaded gasoline, diesel, Jet A-1) to Metamysidopsis insularis, an indigenous tropical mysid species was determined. Approximately 10 000 barrels (bbl) of fuel are consumed daily in Trinidad and Tobago, and about 50 000 bbl are exported. Accidental discharges at points of transfer as well as from inadequate storage facilities, can pose a significant contamination risk to the environment. Organisms were assayed with the WSF under both UV and fluorescent lights. The WSF was prepared using different fuel/seawater (v/v) mixtures. It was found that organisms exposed to diesel, Jet A-1 and unleaded gasoline showed similar toxicological responses under both light regimes, and were more toxic than the leaded gasoline. The results also showed that none of these fuels show photo-induced toxicity. The WSF of the 0.1% mixtures of unleaded gasoline, diesel and Jet A-1 were acutely toxic to M. insularis. However, for the leaded gasoline, only the 0.5% mixture was acutely toxic. The high toxicity of these fuels may be due to the presence of light, more soluble fractions. It is therefore likely that these fuels will have significant impacts in our local environment, if any spills occur.     

Sorption of pyrene on two paddy soils and their particle-size fractions

In the present study, the sorption of pyrene on two kinds of bulk paddy soils, Gleyic Stagnic Anthrosols, and Ferric accumulic Stagnic Anthrosols as well as their particle-size fractions was investigated. The sorption isotherms fitted well with Freundlich equation. For both soils, the clay fraction（ 〈 2μm） and coarse sand fraction（2000-250μm） had higher sorption capacity than fine sand fraction（250-20 μm） and silt fraction（20-2 μm）. The IogKoc values obtained of each soil and its particle-size fractions were similar, proving that SOM content was a key factor affecting pyrene sorption. The Kd values showed a significant correlation with contents of dithionite-extractable Fe in both paddy soils and a good relationship with CEC in Gleyic Stagnic Anthrosols, indicating possible effects of surface properties of particle-size fractions on the sorption of pyrene.