喹啉铜在柑橘中的储藏稳定性、消解动态及膳食暴露风险评估

评估喹啉铜在柑橘中的储藏稳定性、消解动态及膳食暴露风险。在海南、江西两地开展喹啉铜在柑橘中的田间残留试验；利用高效液相色谱法测定柑橘果实样品中的残留量，外标法定量，评估储藏稳定性、残留消解动态和膳食暴露风险。结果表明，柑橘全果样品在?20 ℃储藏180 d，喹啉铜降解率低于10%。喹啉铜在柑橘全果中的消解速率符合一级动力学方程，半衰期为10.2~15.1 d。慢性膳食暴露风险评估结果显示，我国不同年龄段人群喹啉铜的估算每日摄入量为0.0891~1.4584 μg/kg·bw，膳食暴露风险为0.45%~7.29%。喹啉铜在柑橘全果中至少稳定储藏180 d；喹啉铜在柑橘中易降解；在柑橘上规范使用33.5%喹啉铜悬浮剂防治溃疡病，喹啉铜的慢性膳食暴露风险在可接受范围内。     

Continuous in-line decontamination of food-processing surfaces using cold atmospheric pressure air plasma

This study assessed a continuous in-line decontamination system for food contact surfaces and processing equipment that utilized cold atmospheric pressure plasma (CAP) generated from ambient air. The plasma system was evaluated against two common foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes) on stainless steel surfaces and against S Typhimurium on commercial poly[ether]-thermoplastic poly[urethane] (PE-TPU) conveyor belts, under simulated conditions of a food-processing facility. A significant level of microbial inactivation was achieved, up to 3.03 ± 0.18 and 2.77 ± 0.71 logCFU/mL reductions of L. monocytogenes and S. Typhimurium respectively within 10 s total treatment on stainless steel surfaces, and a 2.56 ± 0.37 logCFU/mL reduction of S. Typhimurium within 4 s total treatment on the PE-TPU material, according to a procedure based on the well-established EN 13697:2015 industrial protocol. CAP exposure was shown to have a minor impact on the morphology and composition of the treated surfaces. The results indicated that CAP can be applied for effective and continuous disinfection against common foodborne pathogens in food-processing facilities.Industrial relevanceLow temperature plasmas have shown great promise for microbial decontamination, yet industrial uptake of the technology has been limited due to scaling limitations. In this study, a prototype conveyor-based CAP decontamination system was developed and tested under realistic conditions expected within a food-processing facility. The results showed a high level of antimicrobial action against two common foodborne pathogens within a few seconds of CAP exposure, a timescale in line with industrial line processing speeds. Our findings demonstrated that CAP shows great promise for the continuous in-situ decontamination of food contact surfaces, with the potential to mitigate against the costly downtimes incurred in current production line practices implementing chemical disinfectants.     

食用槟榔货架期内品质控制研究

目的：探究食用槟榔返卤返白的原因。方法：主要通过搜集2000—2020年涉及食用槟榔卤水专利，以及相关工厂案例进行研究与分析。结果：在食用槟榔卤水的制备过程中原料的粒径大小、环境温度与湿度的高低、样品中水分含量及设备的自动化程度均可能造成食用槟榔返卤返白。结论：加工槟榔时应采取以严格控制水分、复配添加剂使用为主，工艺包装调整为辅,给予低温贮藏市售环境的方法，抑制返卤返白的产生。     

导管架平台上部组块双船拆除

为研究复杂海域环境中海洋平台双船拆除方法的安全性与可操作性,采用水动力数值计算与水池模型试验相结合的方法进行研究。将双船水动力耦合计算与水池模型试验进行对比,在相对理想海况下,结合与实际工况接近的规则波作用,进行驳船水动力性能变化与运动响应的幅值分析。在受力分析方面,对甲板耦合装置进行改良设计,对比试验数据与数值计算数据,得到受力在合理范围内的结论。研究内容为实际施工的合理性提出一定的指导性意见。     

Mathematical law of size effect on the flexural property of ceramics

Brittle materials generally exhibit size effects, and the mechanical properties of these materials degrade significantly with an increase in size. However, the mathematical law governing the attenuation degree of mechanical properties with the increase in size is still unknown. In this study, maximum loads of differently sized ceramic test strips were subjected to three point bending tests under two working conditions of equal spans and span amplifications, respectively. Subsequently, the theoretical maximum loads of materials were calculated using the finite element method (FEM). By calculating the difference between the calculated values and the actual maximum loads, the attenuation of mechanical properties of ceramic samples were observed. The results show that the theoretical mechanical properties and the performance attenuation caused by the size effect tend to increase according to the following equation: y=ax³+bx²+cx+d. Therefore, mechanical properties and performance attenuation of any sample exhibiting a size within the experimental range can be predicted by a mathematical law, which was obtained through mechanical tests results of four samples with different sizes. The obtained mathematical law holds great significance for predicting the mechanical properties of materials under size effects.     

Recent advances in black-phosphorus-based materials for electrochemical energy storage

Black phosphorus is a potential candidate material for next-generation energy storage devices and has attracted tremendous interest because of its advantageous structural and electrochemical properties, including its large theoretical capacity, high carrier mobility, and low redox potential. However, its practical applicability has remained low owing to its difficult of preparation, large volume expansion during cycling, and poor electronic conductivity. To this end, there have been significant efforts to improve its synthesis methods and electrochemical performance. A number of black-phosphorus-based composite materials have been developed and investigated. Herein, we provide an up-to-date account of the recent progress made in research on black-phosphorus-based materials for use in rechargeable batteries and supercapacitors. We review the available synthesis methods and basic properties of black phosphorus and discuss its applicability in Li-, Na-, K-, Mg-, Al-ion and Li-S batteries as well as supercapacitors. We also summarize the existing challenges and future opportunities and offer our perspective on the possible directions for future research in this area.     

Recent advances in two-dimensional Pt based electrocatalysts for methanol oxidation reaction

Direct methanol fuel cells (DMFCs) had been attracted considerable attention for its advantages of high energy density, simplified systems and readily transportation and storage of methanol. However, the notoriously sluggish kinetics of methanol oxidation reaction (MOR) of the anode reaction, had greatly affected the commercialization of DMFCs. On one hand, Pt based catalyst are still the most effective MOR catalysts, while the high cost caused by the high loadings of electrocatalyst to compensate the low MOR activity impedes the wide accessible of DMFCs. In addition, the occurrence of catalyst poisoning owing to the strong interaction between Pt and carbon monoxide (CO) generated during the MOR processing, further leading to the fast decay in the performance and stability of MOR electrocatalysts. Two-dimensional (2D) Pt based nanostructures is regarded to be one promising and effective class of MOR electrocatalysts, and attracted much attention due to the high electron mobility, highly exposed active sites, and extraordinary thermal conduction. In this review, the mechanism of MOR was firstly introduced, and then the synthesis conditions, structure characteristics and methanol oxidation performances both in acidic and alkaline dielectric of 2D Pt based nanocatalysts were introduced. Subsequently, we briefly analyzed the structural characteristics of 2D Pt based nanocatalysts and their advantages, including the low platinum loadings, high specific surface area and majority of atomic active sites exposed. Finally, the opportunities and challenges for designing of advanced 2D Pt based nanocatalysts was proposed and discussed.     

Santo Domingo: City profile of the Caribbean's metropolis

As the oldest city of the New World, Santo Domingo has undergone major institutional, political, economic and urban restructuring in five centuries of urban history. This city profile article investigates first the historical urban development of the city and then scrutinizes contemporary urban policies and projects that respond to challenges of rapid growth, inequality, and vulnerability to climate change. The article highlights how centralized policies initiated by divergent political regimes have resulted in a segregated city where Presidents used urban space to leave their legacies without adhering to planning mechanisms. The article also uncovers how rapid growth and absence of urban planning have produced two city making approaches, the “formal” and the “informal” cities converging parallel to each other. Furthermore, as the capital city of a Small Island Developing State, Santo Domingo's recent urban policies are embedded in global frameworks such as the Sustainable Development Goals and the Paris Climate Agreement; in this line, inequality and climate change vulnerabilities continue to be the city's main challenges in the 21rst century.     

基于互信息和PID神经网络的SCR脱硝扰动补偿控制

针对火电厂选择性催化还原(Selective Catalytic Reduction，SCR)烟气脱硝系统机理复杂，工况变化时呈现的不确定性、强扰动等特点，提出了一种基于互信息和PID神经网络的SCR烟气脱硝扰动补偿控制方法。利用PID前向神经网络的学习性能逼近被控对象的逆构成扰动观测器对系统进行反馈补偿，以达到超前消除系统扰动的目的。选取观测扰动和系统扰动的互信息为目标函数，采用改进的帝国竞争算法实现PID神经网络权值的优化调整。设计鲁棒PID控制器来进一步克服被控对象存在的不确定性。仿真实验表明，该方法具有突出的抗干扰能力和较好的鲁棒性，控制品质优于常规的PID控制。