Synergistic effects of structural, crystalline, and chemical defects on the photocatalytic performance of Y-doped ZnO for carbaryl degradation

In this study, a photocatalytic material consisting of ZnO and yttrium-doped ZnO (YZO) nanoparticles was obtained via a facile precipitation conducted under ambient pressure whereby crystalline ZnO was successfully doped with yttrium. YZO had a hexagonal wurtzite polycrystalline structure with smaller crystal and grain sizes than ZnO, which in turn meant larger specific surface area and pore volume. Chemical defects were also produced, which facilitated photocatalytic activity, because such defects can act as reaction centers. The optical band gap magnitude and the diamagnetic nature of YZO were also determined. The structural, crystalline, and chemical defects of YZO synergistically enhanced the photocatalytic degradation of carbaryl; indeed, the kinetic rate constant of this reaction catalyzed by YZO was 11.17 × 10⁻² min⁻¹ under natural sunlight irradiation, higher than the value measured for ZnO (8.68 × 10⁻² min⁻¹). Evidence thus indicates that yttrium-doping effectively modified some properties of ZnO nanoparticles so that YZO nanoparticles proved a suitable photocatalytic material for carbaryl degradation.     

热处理温度对TiO_2结构性质及光催化活性的影响

从晶相组成、晶格缺陷密度、表面羟基含量、晶粒尺寸以及比表面积等方面阐述了热处理温度与TiO2光催化剂结构性质的关系,并就混晶效应、载流子输运/俘获以及尺寸量子效应等对光催化活性的影响进行了讨论。此外,还汇总了对水中典型有机污染物的光催化氧化研究以及相关的催化剂结构性质。     

光催化氧化法去除水中有机氯化物的研究

以TiO_2为催化剂,研究了饮用水中常见的9种氯化有机物的光催化氧化、pH、复氧条件等对光催化氧化效果的影响及有关反应动力学问题。研究表明,光催化氧化法在饮用水深度处理领域。具有很好的应用前景。     

Multi-function adsorbent-photocatalyst MXene-TiO2 composites for removal of enrofloxacin antibiotic from water

MXenes, a new family of two-dimensional transition metal carbides or nitrides, have attracted tremendous attention for various applications due to their unique properties such as good electrical conductivity, hydrophilicity, and ion intercalability. In this work, Ti₃C₂ MXene, or MX, is converted to MX-TiO₂ composites using a simple and rapid microwave hydrothermal treatment in HCl/NaCl mixture solution that induces formation of fine TiO₂ particles on the MX parent structure and imparts photocatalytic activity to the resulting MX-TiO₂ composites. The composites were used for enrofloxacin (ENR), a frequently found contaminating antibiotic, removal from water. The relative amount of the MX and TiO₂ can be controlled by controlling the hydrothermal temperature resulting in composites with tunable adsorption/photocatalytic properties. NaCl addition was found to play important role as composites synthesized without NaCl could not adsorb enrofloxacin well. Adding NaCl into the hydrothermal treatment causes sodium ions to be simultaneously intercalated into the composite structure, improving ENR adsorption greatly from 1 to 6 mg ENR/g composite. It also slows down the MX to TiO₂ conversion leading to a smaller and more uniform distribution of TiO₂ particles on the structure. MX-TiO₂/NaCl composites, which have sodium intercalated in their structures, showed both higher ENR adsorption and photocatalytic activity than composites without NaCl despite the latter having higher TiO₂ content. Adsorbed ENR on the composites can be efficiently degraded by free radicals generated from the photoexcited TiO₂ particles, leading to high photocatalytic degradation efficiency. This demonstrates the synergetic effect between adsorption and photocatalytic degradation of the synthesized compounds.     

两种假单孢菌中二氯酚降解酶活性及其定域研究

对两种有降解二氯酚能力的假单孢菌Ｐｓｅｕｄｏｍｏｎａｓ ｓｐ．ＤＣＰ－１和Ｐｓｅｕｄｏｍｏｎａｓ ｓｐ．ＤＣＰ－２中二氯酚降解酶活性及定域进行了测定，结果表明该酶的活力与菌种、培养等因素有关，与诱导物的关系不显；酶主要定域在膜周及膜内；酶的活力在两种菌中的水平相当；酶的比活力在ＤＣＰ－１的膜周处表现出相当高的水平。     

饮用水低温生物预处理生化活性研究

为了给饮用水低温生物预处理技术的应用与开发提供实验依据，利用陶粒柱连续流生物反应器，于低温（水温２─５℃）季节，对某水源水进行预处理的同时，研究和探讨了陶粒柱生物反应器的生化活性。结果表明，试验装置在低温季节对原水的净化效果较好；陶粒柱反应器内ＴＴＣ－脱氢酶活性沿水流方向自上而下呈梯度分布；低温条件下测定的反应器上、中、下层生物陶粒ＴＴＣ－脱氢酶活性分别为２２．３９、５．７０、０．４０８μｇＴＦ／ｃｍ３·ｈ－１；生物陶粒ＴＴＣ－脱氢酶活性与活性细菌数的时数（ｌｏｇＡＢＮ）之间具有显著相关性（ｒ＝０．８４９３．ｎ＝２５）。因此，可以认为，ＴＴＣ－脱氢酶活性是研究和描述饮用水生物预处理效果的有效参数。     

类羧酸对棕壤中与氮素转化有关的生物活性的影响

类羧酸是一种带有羧基的化工副产品，其主要成分是二羧酸和三羧酸。具有较强的络合能力，可以用做螯合剂。文章通过室内培养实验，研究了类羧酸对棕壤中与氮素转化有关的生物活性的影响。结果表明类羧酸能显著抑制土壤脲酶活性，有效减少尿素水解产物氨的挥发损失；能促进土壤中含氮有机物的分解，并能抑制土壤中氨态氮向硝态氮的转化。另外施用类羧酸还能改善土壤中氮素的有效性，提高土壤的供氮能力。     

Effect of arsenic compounds on Vibrio fischeri light emission and butyrylcholinesterase activity

The effect of organic arsenic compounds and inorganic As(V) and As(III) on Vibrio fischeri luminescence and butyrylcholinesterase activity were evaluated using Microtox and microcalorimetric analysis. Organic arsenic compounds were arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and the antibiotic 4-hydroxy-3-nitrobenzene arsonic acid (HNAA, Roxarsone^(R)). HNAA, As(III) and As(V) were found to inhibit Vibrio fischeri light emission whereas MMA, DMA, AsC and AsB produced only a slight effect. By contrast, only AsC, AsB and As(III) were found to inhibit butyrylcholinesterase activity. Selected article from the 6th European Meeting on Environmental Chemistry, University of Belgrade, Serbia and Montenegro organized by Prof. Dr. Branimir Jovancicevic (www.research.plymouth.ac.uk/ace).     

水杨酸对铅胁迫下黄瓜幼苗叶片膜脂过氧化的影响

以黄瓜幼苗为材料,研究了外源水杨酸对铅胁迫下黄瓜幼苗叶片膜脂过氧化的影响。结果表明:水杨酸使铅胁迫的黄瓜幼苗叶片的丙二醛(MDA)含量下降,可溶性蛋白质含量升高,超氧化物歧化酶(SOD)和过氧化物酶(POD)活性降低;在0~1 mmol.L-1范围内的外源SA对铅胁迫的黄瓜幼苗叶片的丙二醛含量下降量和超氧化物歧化酶活性增加量与水杨酸处理浓度呈正相关,与外源水杨酸处理浓度呈正相关,而过氧化物酶活性增加量与外源水杨酸浓度呈负相关。外源水杨酸的作用可能是通过提高黄瓜叶片对膜脂过氧化的抗性来提高黄瓜幼苗对铅毒害的耐受力。     

Fungicidal activity and molecular modeling of fusarubin analogues from Fusarium oxysporum

Abstract

Fusarubin analogues of Fusarium oxysporum f. sp. ciceris were investigated for antifungal activity in vitro against five soil borne phytopathogenic fungi. 3-O-Methyl-8-O-methyl-fusarubin was inhibitory towards S. sclerotiorum (EC₅₀ 0.33?mmol L^?1) and Sclerotium rolfsii (EC₅₀ 0.38?mmol L^?1). A structure–antifungal activity relationship of fusarubin analogues was established from their activity performance. Possible mechanism of action of these compounds was studied using molecular docking and simulations against three target enzymes which revealed receptor ligand binding affinity. Docking of 3-O-methyl-8-O-methyl-fusarubin into the succinate dehydrogenase site revealed formation of salt bridge, hydrogen bond, π–anion, π–alkyl, and Van der Waals interactions.