Theoretical insights into electronic structures and durability of single-atom Pd/TiN catalysts

Density functional theory (DFT) calculations have been performed to evaluate the metal-support interactions between palladium atom and titanium nitride surface (Pd–TiN). N vacancy sites on defective TiN surface can stabilize Pd single atom under strongly oxidizing conditions, and surface defect-mediated stabilization is accompanied by obvious charge redistributions between Pd and substrate. The adsorption of several gas species on stable Pd–TiN surfaces is also explored to understand catalytic reactions. It is found that O, H, OH, O₂, and CO favorably adsorb on Ti atop site, while CO₂ and H₂ prefer the hollow and Pd atop site, respectively. Moreover, co-adsorption with either H or OH weakens the CO-surface interactions, indicating the CO poisoning effect would be alleviated under both acidic and alkaline conditions. This study provides a perspective to understand the support effect of Pd–TiN, which sheds light on the design of high-performance Pd-based electrodes for proton exchange membrane fuel cells (PEMFCs).     

一起酒店聚餐引起的副溶血性弧菌食物中毒事件分析

目的 对一起酒店聚餐引起的副溶血性弧菌食物中毒事件进行调查和溯源,为研究类似的食物中毒事件提供参考。方法 采用流行病学、食品卫生学和脉冲场凝胶电泳(PFGE)技术等方法,分析此次食物中毒事件。结果 确认食物中毒病例26名,中毒罹患率为3.7%(26/710)；现场采集病例肛拭子26份、酒店厨师肛拭子16份,其中13份标本检出副溶血性弧菌,血清型均为O3∶K6,PFGE指纹图谱一致。结论 综合流行病学、食品卫生学和实验室检测结果分析,确定为一起副溶血性弧菌食物中毒事件,食品安全监管部门应加强对餐饮企业的监督管理,防止此类事件再次发生。     

Detection of bacterial endotoxin in food: New planar interdigital sensors based approach

Food poisoning caused by endotoxins or Lipopolysaccharide (LPS) are associated with Gram-negative bacteria. Two major food-borne pathogens, Escherichia coli and Salmonella are examples of Gram-negative bacteria which cause a large number of outbreaks of food poisoning. New types of planar interdigital sensors have been fabricated with different coating materials to assess their response to endotoxins. A carboxyl-functional polymer, APTES (3-Aminopropyltriethoxysilane) and Thionine were chosen to be coated onto FR4 interdigital sensors. The chosen coating materials have carboxylic or amine functional groups, which were optimized to be stable in water. All coated sensors were immobilized with PmB (Polymyxin B) which has specific binding properties to LPS. The sensors were tested with different concentrations of LPS O111:B4, ranging from 0.1 to 1000 μg/ml. Analyses of sensors’ performance were based on the impedance spectroscopy method. The impedance spectra were modeled using a constant phase-element (CPE) equivalent circuit, and a principal component analysis (PCA) was used for data classification. Sensor coated with APTES has shown better selectivity for LPS detection. The experiments were repeated by coating APTES and immobilizing PmB to a new improve designed of novel interdigital sensors (thin film silicon based sensors). These sensors were observed to have better sensitivity and selectivity to the target biomolecules of LPS. Further experiments were conducted to study the effect of different coating thickness on sensor sensitivity, selectivity and stability. Different food samples contaminated with endotoxin were also tested to verify that the interdigital sensing approach is able to be used for endotoxin detection.     

2012—2018年广州市海珠区不同来源沙门菌分离株血清学分型及生化分析

目的 了解2012—2018年广州市海珠区沙门菌食品污染物监测分离株、食物中毒分离株、从业人员健康体检分离株的血清学分型及生化分析。方法 2012—2018年分离416株沙门菌,包括28株食物中毒菌株、5株食品污染物监测菌株、383株体检人群菌株,对其进行血清学分型、生化鉴定。结果 416株沙门菌鉴定出40个血清型,其中鼠伤寒沙门菌56株(13.5%),肠炎沙门菌46株(11.1%),德尔卑沙门菌41株(9.9%),其他血清型273株(65.6%)。沙门菌以A～F群血清型为主,同时检出多例罕见血清型。结论 广州市海珠区人群中沙门菌的血清型众多且分布广,鼠伤寒沙门菌、肠炎沙门菌、德尔卑沙门菌为海珠区优势沙门菌血清型；开展沙门菌血清型监测,对该菌引发的疾病有重要意义。     

Experimental investigation on influences of methanol reformate impurities in performances of high temperature proton exchange membrane fuel cells

Even though the methanol reformate can be fed into the high temperature proton exchange membrane fuel cell, the influences of different reformate components on the fuel cell are still unclear. This work investigates the effects of CO, CO₂, H₂O, and CH₃OH in the fuel gas on the fuel cell performances. The distribution of relaxation times and equivalent circuit model are employed for analysis. The results show the increase of anodic charge and mass transfer resistances are main factors of CO poisoning which results in 77 mV overpotential. The maximum overpotential difference between CO₂ and Ar is only 4 mV, which means the dilution effect of CO₂ is similar to Ar. H₂O decreases the Ohmic and anodic charge transfer resistances and reducing the overpotential by 10 mV. CH₃OH below 3% has slight positive effect on the fuel cell performance. However, 5% CH₃OH results in high overpotential of 36 mV.     

Biosafe Saccharomyces Cerevisiae Immobilized Nanofibrous Aerogels for Integrated Lead Removal in Human Body

Emerging adsorption technology shows great potential for Pb²⁺ removal in the human body because of its high adsorption efficiency and easy operation. However, biosafety concerns in the human body limit the development of adsorbents in integrated lead removal for acute poisoning in humans from the gastrointestinal tract and even the blood. In this work, highly bio-safe and natural saccharomyces cerevisiae cells are immobilized on the interworking natural regenerated cellulose nanofibers network for integrated lead removal in the human body. High intrinsic biosafety of the aerogel is guaranteed due to the biocompatibility of aerogel composition and the absence of cross-linking substances. Attributing to the porous structure of cellulose nanofibrous scaffolds, saccharomyces cerevisiae cells are protected from shedding, and considerable loading sites for saccharomyces cerevisiae cells are ensured. Simultaneously, abundant functional groups on the saccharomyces cerevisiae cells exhibit superior adsorption ability with a saturated adsorption capacity of lead ions as high as 107 mg g⁻¹ in the aquatic environment. After adsorption, Pb²⁺ concentration decreases from 879.70 to 248.53 µg L⁻¹ in the intestinal phase and from 400 to 186.29 µg L⁻¹ (within a safe level) in blood, providing an attractive strategy for detoxification of integrated lead in the human body.     

高温高尘SCR超低排放实例

为了满足政府的排放要求，赞皇公司先后在2020年下半年对其4000t/d生产线进行了分级燃烧和SNCR的升级改造。从SCR建设方案选择、技术路线注意事项、温降控制、系统阻力控制、SCR与SNCR耦合脱硝高效应用技术、SCR调试与试运行、SCR运行效果等方面做经验分享，供企业借鉴和指导。     

Wireless Sensor Network-based Detection of Poisonous Gases Using Principal Component Analysis

This work utilizes a statistical approach of Principal Component Analysis (PCA) towards the detection of Methane (CH₄)-Carbon Monoxide (CO) Poisoning occurring in coal mines, forest fires, drainage systems etc. where the CH₄ and CO emissions are very high in closed buildings or confined spaces during oxidation processes. Both methane and carbon monoxide are highly toxic, colorless and odorless gases. Both of the gases have their own toxic levels to be detected. But during their combined presence, the toxicity of the either one goes unidentified may be due to their low levels which may lead to an explosion. By using PCA, the correlation of CO and CH₄ data is carried out and by identifying the areas of high correlation (along the principal component axis) the explosion suppression action can be triggered earlier thus avoiding adverse effects of massive explosions. Wireless Sensor Network is deployed and simulations are carried with heterogeneous sensors (Carbon Monoxide and Methane sensors) in NS-2 Mannasim framework. The rise in the value of CO even when CH₄ is below the toxic level may become hazardous to the people around. Thus our proposed methodology will detect the combined presence of both the gases (CH₄ and CO) and provide an early warning in order to avoid any human losses or toxic effects.     

A Highly Efficient pH-Universal HOR Catalyst with Engineered Electronic Structures of Single Pt Sites by Isolated Co Atoms

Developing a high-efficiency, stable, and CO-toxicant-resistant low-cost hydrogen oxidation reaction (HOR) electrocatalyst is challenging but is vital for practical proton/anion exchange membrane fuel cells. Herein, an efficient pH-universal HOR catalyst Pt₁@Co₁CN is fabricated, in which the electronic structure of single Pt sites is modulated by isolated Co atoms pre-anchored on nitrogen-doped carbon. Pt₁@Co₁CN exhibits superior HOR activity and durability under pH-universal media than Pt₁@CN (anchored single Pt atoms on nitrogen-doped carbon) and commercial PtRu/C and Pt/C. More importantly, Pt₁@Co₁CN possesses much better CO anti-poisoning ability than Pt₁@CN and commercial PtRu/C and Pt/C. It is speculated that the superior pH-universal HOR performance can be attributed to the inter-regulation of adjacent Co and Pt sites, leading to the downshift of anti-bonding state and consequently strengthening the *H adsorption, which promotes the kinetics of HOR.