Metal Single-Atom Cocatalyst on Carbon Nitride for the Photocatalytic Hydrogen Evolution Reaction: Effects of Metal Species

Single-atom (SA) catalysts exhibit high activity in various reactions because there are no inactive internal atoms. Accordingly, SA cocatalysts are also an active research fields regarding photocatalytic hydrogen (H₂) evolution which can be generated by abundant water and sunlight. Herein, it is investigated whether 10 transition metal elements can work as an SA on graphitic carbon nitride (g-C₃N₄; i.e., gCN), a promising visible-light-driven photocatalyst. A method is established to prepare SA-loaded gCN at high loadings (weight of ≈3 wt.% for Cu, Ni, Pd, Pt, Rh, and Ru) by modulating the photoreduction power. Regarding Au and Ag, SAs are formed with difficulty without aggregation because of the low binding energy between gCN and the SA. An evaluation of the photocatalytic H₂-evolution activity of the prepared metal SA-loaded gCN reveals that Pd, Pt, and Rh SA-loaded gCN exhibits relatively high H₂-evolution efficiency per SA. Transient absorption spectroscopy and electrochemical measurements reveal the following: i) Pd SA-loaded gCN exhibits a particularly suitable electronic structure for proton adsorption and ii) therefore they exhibit the highest H₂-evolution efficiency per SA than other metal SA-loaded gCN. Finally, the 8.6 times higher H₂-evolution rate per active site of Pd SA is achieved than that of Pd-nanoparticles cocatalyst.     

自卸车卸载工况下副车架的受力分析

通过对某厂生产的自卸车卸载工况力学模型的分析计算,得出了自卸车副车架在卸栽工况下所受的各个关键力的数值;利用有限元软件对该自卸车副车架的模型进行了静态分析,找出了在卸载工况下,该自卸车副车架易发生应力集中的部位,为该车的进一步改进提供了依据.     

脉冲电沉积法制备Al基Pb—WC—Ce02复合惰性阳极

为了制备性能优良的Al基Pb—WC—CeO：惰性阳极材料,考察了WC、CeO：颗粒浓度对阴极极化的影响,正向脉冲参数、温度和搅拌对沉积速率以及复合镀层表面形貌的影响,并研究了其在锌电解液中的耐蚀性能,确定了脉冲电沉积制备Al基Pb-WC-C02复合镀层的最佳工艺条件：基础镀铅液中添加40g／LWC（粒径1斗m）,30g...     

Detection of Verotoxigenic Escherichia coli O157 and O26 in food by plating methods and LAMP method: a collaborative study

In order to establish a rapid and sensitive method for the detection of Verotoxigenic Escherichia coli O157 and O26, a collaborative study was conducted focusing on a comparison of the efficiency of loop-mediated amplification (LAMP) assay targeting the Verocytotoxin (also called Shiga toxin) gene, utilizing a direct plating method and a plating method with immunomagnetic separation (IMS-plating method) using various agar media. In combination with enrichment with the modified EC supplemented with novobiocin, E. coli O157 was detected in most samples of ground beef and alfalfa sprouts by LAMP assay, the direct plating method and the IMS-plating method. E. coli O26 was detected in approximately 100% of the food samples by LAMP assay. However, the IMS-plating and direct plating methods recovered 80 and 50% in ground beef samples, respectively. As a result, it was demonstrated the LAMP assay is superior to the IMS-plating method. Based on these results, it appears LAMP assay is effective as a screening assay to detect E. coli O157 and O26 from positive samples.     

3 种木耳多糖的抗氧化活性与抑菌能力比较分析

目的：研究玉木耳、黑木耳与毛木耳3 种木耳多糖的抗氧化活性与抑菌能力。方法：利用水提醇沉法获得了3 种木耳的多糖,并测定了其多糖含量;采用分光光度法分别测定了3 种木耳多糖的总抗氧化能力,羟自由基、超氧阴离子自由基、1,1-二苯基-2-三硝基苯肼自由基和亚硝酸根离子清除能力;同时进行了大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌的抑菌实验。结果：相同提取条件下,玉木耳、黑木耳与毛木耳的粗多糖提取率分别为13.87%、11.26%、7.91%,其中3 种木耳多糖质量分数分别为49.22%、41.50%和37.97%;总抗氧化活性检测结果显示毛木耳多糖的总抗氧化能力最高,黑木耳多糖与玉木耳多糖抗氧化能力相当;其中玉木耳多糖对羟自由基清除能力略强于黑木耳多糖,且二者的超氧阴离子自由基清除能力相当,均强于毛木耳多糖;3 种木耳多糖对DPPH自由基的清除作用较明显,其中玉木耳多糖相对较优,可达80%;此外,黑木耳多糖对亚硝酸根离子的清除能力最好,略优于其他两种木耳多糖。对常见细菌的抑制作用而言,3 种木耳多糖均对大肠杆菌有一定的抑制作用,但黑木耳多糖和毛木耳多糖对金黄色葡萄球菌和枯草芽孢杆菌抑制作用较弱;仅玉木耳多糖对金黄色葡萄球菌和枯草芽孢杆菌有较好的抑制作用。结论：3 种木耳多糖具备各自不同的抗氧化活性与抑菌能力,且差异较为明显。     

Multiple evaluations of the removal of pollutants in road runoff by soil infiltration

Groundwater replenishment by infiltration of road runoff is expected to be a promising option for ensuring a sustainable urban water cycle. In this study, we performed a soil infiltration column test using artificial road runoff equivalent to approximately 11-12 years of rainfall to evaluate the removal of pollutants by using various chemical analyses and bioassay tests. These results indicated that soil infiltration treatment works effectively to remove most of the pollutants such as organic matter (chemical oxygen demand (CODMn) and dissolved organic carbon (DOC)), P species, polycyclic aromatic hydrocarbons (PAHs), numerous heavy metals and oestrogenic activities. Bioassay tests, including algal growth inhibition test, Microtox and mutagen formation potential (MFP) test, also revealed effective removal of toxicities by the soils. However, limited amounts of NO3, Mn, Ni, alkaline earth metals, perfluorooctane sulphonate (PFOS) and perfluorooctane sulphonamide (FOSA) were removed by the soils and they possibly reach the groundwater and cause contamination.     

Enantioselective addition Of diketene to aldehydes promoted by chiral schiff base—titanium alkoxide complex. Application to asymmetric synthesis of potential inhibitors of HMG coenzyme reductase

Highly enantioselective addition of diketene to aldehydes was achieved by using novel Schiff base—titanium alkoxide complexes. Up to 92% ee of 5-hydroxy-3-oxoesters was obtained. This procedure provides an efficient method for the asymmetric synthesis of potential inhibitors of HMG coenzyme reductase.     

盐干海参的2种核酸提取方法比对及其分子鉴定

目的 建立盐干海参的核酸提取及其分子鉴定方法。方法 选取5种盐干海参, 采用直接处理、洗涤处理和浸泡处理3种处理方式, 比较磁珠法和离心柱法两种核酸抽提方式的提取质量, 并采用聚合酶链式反应(polymerase chain reaction, PCR)法对提取的核酸进行分析确认。结果 同一种抽提方式不同海参处理组间核酸质量没有显著差异, 而两种抽提方式间核酸质量差异显著, 其中磁珠法提取的核酸得率高、纯度高, 而离心柱法提取的核酸得率及纯度均偏低。经PCR扩增验证, 磁珠法提取的核酸效果较佳。将扩增产物进行测序及系统进化分析发现5种海参实际种类与标注名称仿刺参存在较大差异。结论 盐干海参处理方式对核酸提取结果影响不大, 磁珠法提取核酸效果较好,单纯依靠COI和16S rRNA基因通用引物并不能对所有的海参种类进行鉴定。     

Metal-Induced Structural Switching of a Folded Quinone-Sandwiched Porphyrin

We report the synthesis of a novel quinone-sandwiched porphyrin in which two benzoquinones are connected oppositely at the meso positions of a porphyrin through rigid 3-amido 2,2′-bipyridine linkers. ¹H-NMR and single crystal X-ray analyses revealed that the quinone-sandwiched porphyrin has a folded structure in which the porphyrin unit was inserted into the two quinone moieties via π-stacking. Insertion of a Zn(II) ion into the porphyrin center induced a drastic conformational change which is resulted in coordination of the oxygen atoms of both benzoquinone moieties to the Zn-porphyrin to afford a 6-coordinated structure.     

无线局域网MAC地址欺骗攻击的检测

在无线网络中,攻击者可以修改自己无线网卡的MAC地址为合法站点的地址,从而可以绕过访问控制列表,窃取网络信息,这给无线网络安全带来很大的危害。为了有效地防止和检测MAC地址欺骗攻击,文中在分析无线局域网MAC地址欺骗攻击的基础上,提出一种利用数据包序列号检测MAC地址欺骗攻击的检测方法。该方法不仅能够有效检测MAC地址欺骗攻击,并能迅速查找到入侵源,维护网络的性能和安全。经过试验证明,该方法具有良好的性能。