活性粉末混凝土(RPC)的断裂力学性能

在试验及观察的基础上,对活性粉末混凝土的断裂过程进行定性分析,给出活性粉末混凝土的裂纹发展原理及钢纤维的增韧机理,并分析其不同于普通混凝土的两个基本断裂特征。介绍了利用缺口梁三点弯曲试验确定混凝土拉伸软化本构方程的方法。基于Hillerborg模型,提出活性粉末混凝土的拉伸软化模型,根据三点弯曲断裂试验结果,确定出活性粉末混凝土的双线性拉伸软化曲线中的具体参数。据该软化曲线公式,计算出的活性粉末混凝土断裂能同试验得出的值相比,误差仅为0.9%。笔者得出的双线性软化曲线能较精确地反映活性粉末混凝土材料的断裂特性,可为今后进行RPC裂缝的分析和预测提供定量计算的依据,对于研究活性粉末混凝土的断裂能、尺寸效应等问题也很具意义。     

青霉菌X5对活性艳蓝KN-R脱色研究

采用梯度平板筛选法，从染布厂废水池污泥中分离到一株对蒽醌染料KN－R有较强脱色能力的青霉菌X5（Penicillium sp.)，并考察该菌在不同温度，pH，培养时间，染料浓度，菌量及不同碳源氮源条件下对活性艳蓝KN－R的脱色情况，结果表明,在20－40℃温度范围内该菌对活性艳蓝KN－R的脱色率均在95％以上，其最佳脱色温度为25℃，pH为4．0，培养时间为48h，染料浓度，菌量对染料脱色有一定影响，该菌对碳源、氮源具有较宽适应范围，在最佳条件下，该菌对染料的脱色率达99．3％。     

The future of food security in the Three Areas of Sudan

Currently, the pace of recovery in the 'Three Areas' is moving faster than the implementation of the Comprehensive Peace Agreement (CPA). This gap is leading to greater imbalances in income, unsustainable urbanization, overexploitation of the environment and resource based conflict. Unless regulated, the likely result will be chronic poverty and an undermining of the success of the CPA. Agencies must be mindful of how they provide assistance so that they support the CPA. The analysis of food security should take place in the context of a larger political, social and economic analysis of the emerging situation. The least developed areas should be prioritised and interventions should provide benefits to the full range of socioeconomic groups. WFP must identify its role in the wider and integrated response. It should support the emerging peace process and the key reforms. If WFP chooses to consolidate its activities, it will require capable strategic partners. If it chooses to invest more in building the capacity of government and community structures, it must improve its skill base and field presence     

无花果曲霉菌丝球对活性艳蓝KN-R的脱色研究

生物吸附法是染料废水处理中很有前途的一种方法。本文将培养的无花果曲霉菌丝球用于蒽醌染料活性艳蓝KN-R的脱色，研究了培养时间、温度、转速、pH值及盐浓度、不同碳源、不同氮源对菌丝球脱色的影响；比较了活菌与死菌的脱色效果；探讨了菌丝球重复利用对脱色率的影响。结果表明：培养时间为72h，温度为33℃，转速为150rpm，pH值为6．0，盐浓度为0.5％，以乳糖为碳源、硝酸钠为氮源时，菌丝球对活性艳蓝KN-R的脱色效果最好：活菌对染料的吸附性能比死菌好；菌丝球在重复利用了四次后，脱色率仍达85．7％。     

染料脱色菌的筛选及对活性艳红X-3B的脱色研究

从广州某印染厂生化处理池的活性污泥中筛选到三株对活性艳红X-3B具有高效脱色作用的真菌,其中菌株HMX-3的脱色能力最强。考察了培养时间、温度、培养方式、pH值以及染料浓度对HMX-3脱色能力的影响。结果表明,菌株HMX-3对150mg/L X-3B的24h脱色率达65.8%,经60h可使其完全脱色;HMX-3对活性艳红X-3B脱色的最适温度为25℃~35℃,最佳pH值为6~8,且振荡培养较静置培养条件下的脱色率高;随染料浓度的增加,脱色率降低,但对于400mg/L的X-3B在72h时的脱色率可达86.7%。     

Citrobacter sp.CK3对活性红KN-3B的脱色反应动力学研究

采用脱色菌Citrobacter sp. CK3,以活性红KN-3B染料为处理对象,在厌氧批式反应条件下,系统考察了pH值,温度和染料浓度对脱色反应速度的影响;通过动力学模拟及反应过程中染料的UV-Vis扫描图分析,探讨了脱色反应机理。结果表明:Citrobacter sp. CK3对活性红KN-3B的脱色反应的适宜pH为7～9;脱色反应速度在温度为32℃时达到最大。染料初浓度从57 mg/L逐渐增大到458 mg/L时脱色率逐渐降低。脱色过程中染料的偶氮键发生断裂,脱色反应符合二级反应动力学。     

Porous FeOx/BiVO4-δS0.08：Highly efficient photocatalysts for the degradation of Methylene Blue under visible-light illumination

Porous S-doped bismuth vanadate with an olive-like morphology and its supported iron oxide （y wt.% FeOx/BiVO4-δS0.08, y = 0.06, 0.76, and 1.40） photocatalysts were fabricated using the dodecylamine-assisted alcohol-hydrothermal and incipient wetness impregnation methods, respectively. It is shown that the y wt.% FeOx/BiVO4-δS0.08 photocatalysts contained a monoclinic scheetlite BiVO4 phase with a porous olive-like morphology, a surface area of 8.8-9.2 m^2/g, and a bandgap energy of 2.38-2.42 eV. There was co-presence of surface Bi^5＋, Bi^3＋, V^5＋, V^3＋, Fe^3＋, and Fe^2＋ species in y wt.% FeOx/BiVO4-δS0.08. The 1.40 wt.% FeOx/BiVO4-δS0.08 sample performed the best for Methylene Blue degradation under visible-light illumination. The photocatalytic mechanism was also discussed. We believe that the sulfur and FeOx co-doping, higher oxygen adspecies concentration, and lower baudgap energy were responsible for the excellent visible-light-driven catalytic activity of 1.40 wt.% FeOx/BiVO4-δS0.08.     

Formation mechanism and control strategy for particulate nitrate in China

Over the past decade, fine particulate matter (PM) pollution in China has been abated significantly, benefiting from strict emission control measures, but particulate nitrate continues to rise. Here, we review the progress in particulate nitrate (pNO₃⁻) pollution characterization, nitrate formation mechanisms, and the proposed control strategies in China. The spatial and temporal distributions of pNO₃⁻ are summarized. The current status of knowledge on the chemical mechanism is updated, and the significance of its formation pathways is assessed by various approaches such as field observation and modelling of nitrate production rate, as well as isotopic analysis. The factors impacting pNO₃⁻ formation and the corresponding pollution regulation strategies are discussed, in which the importance of atmospheric oxidation capacity and ammonia are addressed. Finally, the challenges and open questions in pNO₃⁻ pollution control in China are outlined.     

Reproductive toxicity and underlying mechanisms of di(2-ethylhexyl) phthalate in nematode Caenorhabditis elegans

DEHP (di(2-ethylhexyl) phthalate) is an endocrine disruptor commonly found in plastic products that has been associated with reproduction alterations, but the effect of DEHP on toxicity is still widely unknown. Using DEHP concentrations of 10, 1, and 0.1 mg/L, we showed that DEHP reduced the reproductive capacity of Caenorhabditis elegans after 72 hr. of exposure. DEHP exposure reduced the reproductive capacity in terms of decreased brood sizes, egg hatchability (0.1, 1 and 10 mg/L), and egg-laying rate (1 and 10 mg/L), and increased numbers of fertilized eggs in the uterus (1 and 10 mg/L). DEHP also caused damage to gonad development. DEHP decreased the total number of germline cells, and decreased the relative area of the gonad arm of all exposure groups, with worms in the 1 mg/L DEHP exposure group having the minimum gonad arm area. Additionally, DEHP caused a significant concentration‐dependent increase in the expression of unc-86. Autophagy and ROS contributed to the enhancement of DEHP toxicity in reducing reproductive capacity, and glutathione peroxidase and superoxide dismutase were activated as the antioxidant defense in this study. Hence, we found that DEHP has a dual effect on nematodes. Higher concentration (10 mg/L) DEHP can inhibit the expression of autophagy genes (atg-18, atg-7, bec-1, lgg-1 and unc-51), and lower concentrations (0.1 and 1 mg/L) can promote the expression of autophagy genes. Our data highlight the potential environmental risk of DEHP in inducing reproductive toxicity toward the gonad development and reproductive capacity of environmental organisms.     

A critical review on the application of biochar in environmental pollution remediation: Role of persistent free radicals (PFRs)

Biochar as an emerging carbonaceous material has exhibited a great potential in environmental application for its perfect adsorption ability. However, there are abundant persistent free radicals (PFRs) in biochar, so the direct and indirect PFRs-mediated removal of organic and inorganic contaminants by biochar was widely reported. In order to comprehend deeply the formation of PFRs in biochar and their interactions with contaminants, this paper reviews the formation mechanisms of PFRs in biochar and the PFRs-mediated environmental applications of biochar in recent years. Finally, future challenges in this field are also proposed. This review provides a more comprehensive understanding on the emerging applications of biochar from the viewpoint of the catalytic role of PFRs.