2017—2019年普洱市食品中化学污染物监测结果分析

目的了解2017—2019年普洱市食品风险监测中化学污染物状况。方法 2017—2019年在普洱市辖区内各区县农贸市场、商店等采集不同种类食品样本进行食品接触材料污染物、食品添加剂、兽药残留、元素、农药残留等项目的检测。结果 2017—2019年普洱市食品超标率分别为食品接触材料污染物32.00%、食品添加剂24.32%、兽药残留3.17%、元素3.03%、农药残留0.73%。结论普洱市常见食品中有部分化学污染物(五氯酚钠、含铝添加剂、铅、砷、强力霉素、恩诺沙星、甲拌磷、甲拌磷砜等)超标,对人体健康造成危害。各相关部门应加强监管。     

传统培养法与荧光PCR法检测弧菌的方法评价

目的比较标准检测方法与杜邦BAX System Q7快速检测方法检测副溶血性弧菌、霍乱弧菌和创伤弧菌。方法采用GB 4789.7—2013《食品微生物学检验副溶血性弧菌检验》、SN/T 1022—2010《进出口食品中弧菌霍乱弧菌检验方法》、DBS 13/004—2016《食品安全地方标准创伤弧菌检验》标准和杜邦BAX System Q7系统操作方法对1份同时污染副溶血性弧菌、霍乱弧菌和创伤弧菌的样品进行检测。结果BAX System Q7操作方法与标准操作方法检测结果一致,其中BAX System Q7可同时检测3种弧菌,用时20 h,而标准操作方法至少需要6 d。结论BAX System Q7检测方法与标准方法均具备高准确性,但相较于标准检测方法,BAX System Q7检测方法鉴定更快速、操作更简便,且3种弧菌可以同时鉴定。     

超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法快速检测茶叶中草甘膦、草铵膦及其代谢物残留

摘 要：目的 建立一种非衍生化处理, 直接测定茶叶中草甘膦、草铵膦及代谢物的的快速分析方法。方法 茶叶样品经酸化的同体积甲醇-水进行提取, 经Oasis PRiME HLB 固相萃取柱通过式净化, 并通过超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法对样品进行测定。结果 茶叶中草甘膦、草铵膦及代谢物在1.0~50 ng/mL的范围内, 线性关系良好(r2＞0.999), 平均回收率在83.7%~92.2%之间, 相对标准偏差低于10%, 检出限为0.01 mg/kg, 定量限为0.05 mg/kg。结论 此方法前处理简便快速, 且准确性好、灵敏度高, 可实现茶叶中草甘膦、草铵膦及其代谢物的快速筛查。     

Interesting Copper(I) Coordination Polymers of Heterocyclic Monothioether Ligand Containing Long S-Hexadecyl Chain: Syntheses,Structures and Properties

Two structurally related heterocyclic monothioether ligands containing long S-alkyl(hexadecyl) chain, 2-methyl-5-(1-n-hexadecylsulfanyl)-1,3,4-thiadiazole (L ¹ ) and 2-(1-n-hexadecylsulfanyl) pyridine (L ² ), have been designed, and two CuI complexes with these ligands, [Cu₄I₄(L¹)₂] _n (1) and [Cu₄I₄(L²)₂] _n (2), have been synthesized and characterized by IR, elemental analysis, UV–vis spectra, thermal analysis and X-ray diffraction analysis. Single-crystal X-ray analyses show that two complexes are all 1-D coordination polymer with a double-stranded stair CuI-chain. Optical diffuse-reflection spectra results complex 1 and 2 have the properties of the semiconductor.     

Direct electrochemistry of catalase at amine-functionalized graphene/gold nanoparticles composite film for hydrogen peroxide sensor

Direct electrochemistry and electrocatalysis of catalase (Cat) was studied based on a nano-composite film consisting of amine functionalized graphene and gold nanoparticles (AuNPs) modified glassy carbon electrode. Graphene was synthesized chemically by Hummers and Offeman method and then was functionalized with amino groups via chemical modification of carboxyl groups introduced on the graphene surface. The nano-composite film showed an obvious promotion of the direct electron transfer between Cat and the underlying electrode, which attributed to the synergistic effect of graphene-NH₂ and AuNPs. The resultant bioelectrode retained its biocatalytic activity and offered fast and sensitive H₂O₂ quantification. Under the optimized experimental conditions, hydrogen peroxide was detected in the concentration range from 0.3 to 600 μM with a detection limit of 50 nM at S/N = 3. The biosensor exhibited some advantages, such as short time respond (2 s), high sensitivity (13.4 μA/mM) and good reproducibility (RSD = 5.8%).     

Characterization of protein immobilization on nanoporous gold using atomic force microscopy and scanning electron microscopy

Nanoporous gold (NPG), made by dealloying low carat gold alloys, is a relatively new nanomaterial finding application in catalysis, sensing, and as a support for biomolecules. NPG has attracted considerable interest due to its open bicontinuous structure, high surface-to-volume ratio, tunable porosity, chemical stability and biocompatibility. NPG also has the attractive feature of being able to be modified by self-assembled monolayers. Here we use scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize a highly efficient approach for protein immobilization on NPG using N-hydroxysuccinimide (NHS) ester functionalized self-assembled monolayers on NPG with pore sizes in the range of tens of nanometres. Comparison of coupling under static versus flow conditions suggests that BSA (Bovine Serum Albumin) and IgG (Immunoglobulin G) can only be immobilized onto the interior surfaces of free standing NPG monoliths with good coverage under flow conditions. AFM is used to examine protein coverage on both the exterior and interior of protein modified NPG. Access to the interior surface of NPG for AFM imaging is achieved using a special procedure for cleaving NPG. AFM is also used to examine BSA immobilized on rough gold surfaces as a comparative study. In principle, the general approach described should be applicable to many enzymes, proteins and protein complexes since both pore sizes and functional groups present on the NPG surfaces are controllable.     

Using Sorted Switching Median Filter to remove high-density impulse noises

We propose a novel Sorted Switching Median Filter (i.e. SSMF) for effectively denoising extremely corrupted images while preserving the image details. The center pixel is considered as “uncorrupted” or “corrupted” noise in the detecting stage. The corrupted pixels that possess more noise-free surroundings will have higher processing priority in the SSMF sorting and filtering stages to rescue the heavily noisy neighbors. Five noise models are considered to assess the performance of the proposed SSMF algorithm. Several extensive simulation results conducted on both grayscale and color images with a wide range (from 10% to 90%) of noise corruption clearly show that the proposed SSMF substantially outperforms all other existing median-based filters.     

High output impedance current-mode first-order allpass networks with four grounded components and two CCIIs

Eight current-mode first-order allpass networks using second-generation current conveyors (CCII) are presented. Each of the proposed circuits employs two CCIIs, two grounded capacitors and two grounded resistors. The networks offer high output impedances. Experimental results are also included.     

The Adaptive Ontology-Based Personalized Recommender System

Recommender systems provide strategies that help users search or make decisions within the overwhelming information spaces nowadays. They have played an important role in various areas such as e-commerce and e-learning. In this paper, we propose a hybrid recommendation strategy of content-based and knowledge-based methods that are flexible for any field to apply. By analyzing the past rating records of every user, the system learns the user’s preferences. After acquiring users’ preferences, the semantic search-and-discovery procedure takes place starting from a highly rated item. For every found item, the system evaluates the Interest Intensity indicating to what degree the user might like it. Recommender systems train a personalized estimating module using a genetic algorithm for each user, and the personalized estimating model helps improve the precision of the estimated scores. With the recommendation strategies and personalization strategies, users may have better recommendations that are closer to their preferences. In the latter part of this paper, a real-world case, a movie-recommender system adopting proposed recommendation strategies, is implemented.     

Designing parameter optimization of a Parallel-Plain Fin heat sink using the grey-based fuzzy algorithm with the orthogonal arrays

In this paper, a grey-based fuzzy algorithm with the orthogonal arrays is employed to find the optimal designing parameters' setting for a heat sink with the Parallel-Plain Fin (PPF) on the multiple thermal performance characteristics. The proposed algorithm, coupling the grey relational analysis with the fuzzy logic, obtains a grey–fuzzy reasoning grade to evaluate the multiple performance characteristics according to the grey relational coefficient of each performance characteristic. In the present study, the designing parameters of the heat sink include the height of fin, the width of gap between fins, the width of slot, the number of slot and the air speed. The design of experiment (DOE) adopts the L₁₆(4⁵) orthogonal arrays table which is four levels and five factors type of factorial design. The average convective heat transfer coefficient, the thermal resistance and the pressure drop are considered as the multiple thermal performance characteristics and explored in the experiment. In addition, the response table, response graph and the analysis of variance (ANOVA) are used to find the optimal settings and the influence of designing parameters on the multiple performance characteristics. The results of confirmation tests with the optimal settings of designing parameters have obviously shown that the multiple thermal performance characteristics are effectively improved through these procedures.