基于单总线的小环境温度监测系统研究

针对目前小环境温度监测系统的现状,介绍了单总线技术和DS18B20数字式传感器的特点。以AT89C51单片机为核心控制部件,结合小环境温度控制系统的要求,设计了基于单总线技术的小环境温度监测系统,并给出了该监测系统的硬件结构和进行了相应的软件设计。从实际应用结果表明,该系统具有测量精度高、抗干扰性强、可靠性高和性价比好等特点,在工程实际应用中具有重要意义。     

Unveiling the mechanism of controllable CO2 hydrogenation by group VIB metal single atom anchored on N-doped graphite: A density functional theory study

CO₂ hydrogenation has raised considerable interest due to concerns about climate change. Realizing low-temperature reverse water gas shift (rWGS) reaction remains a significant challenge in the context of coupling it with the C–C growth reactions to convert CO₂ to C₂₊ fuels. We carried out systematic DFT simulations to unveil the underlying low-temperature mechanism for the selective hydrogenation of CO₂ to produce CO, over a variety of metal-based single atom catalysts (SACs) supported on the nitrogen-doped graphite. Group VIB metal-based SACs outperformed other 15 metal candidates in terms of versatile capacities in both selective activation of CO₂ molecule and facilitating escaping of CO and H₂O. Mo₁/N₃-Gt was especially outstanding by giving rise to spontaneous production of CO and O1 through an effective electron injection into the CO₂ molecule. Water formation has been identified as the potential rate-controlling step in such a catalytic reaction over Mo₁/N₃-Gt with an energy barrier of 1.10 eV. Herein, the H migration played a pivotal role and had tight affinity to the charge of H1 on the active site of catalyst. The dynamic coordination environment of Mo^δ+ was revealed to be the dominant factor affecting the surface H1 charge, leading to a variety of hydrogenation behaviors. The electron-deficient ligands of CO₂ and O1 on Mo₁/N₃-Gt, as well as additional adsorbed H₂, were effective in adjusting the 4d and 5s electronic structure of central Mo and consequently resulted in nearly electric neutral surface H1s, thus most benefiting the hydrogenation process. The optimal charge of the coordinated Mo for an outstanding selective hydrogenation performance in this scenario was found to be no less than +1.7e.     

体外诱导微环境对骨髓间充质干细胞成神经分化的影响及分化后的自发逆转现象

目的体外定向诱导大鼠骨髓间充质干细胞(Mesenchymal stem cells,MSCs)成神经分化,并探讨诱导微环境对其分化的影响及分化后的自发逆转现象。方法体外分离培养大鼠MSCs,流式细胞仪检测细胞表面标志。采用改良神经元诱导液[Modified neuronal induction media(MNM)]定向诱导MSCs,免疫荧光检测神经细胞表面标志。观察胎牛血清(FBS)浓度、细胞密度、MNM剂量、新鲜与使用过的MNM等不同诱导微环境对MSCs成神经分化的影响。结果 MSCs经MNM诱导后,6h即可见尼氏体,表达神经元特异性表面标志神经元特异性烯醇化酶(NSE)、巢蛋白(Nestin)和微管相关蛋白-2(MAP-2)。随着诱导微环境的改变,MSCs成神经分化率及神经元表面标志表达亦发生改变,且分化后的神经元样细胞可自发逆转。结论 MSCs能够在MNM微环境中定向成神经分化,但诱导微环境的改变可以从量和质两个层面影响MSCs定向分化。     

调节性树突状细胞在免疫相关性疾病中的研究进展

树突状细胞(Dendritic cell,DC)是机体免疫系统中一组形态和功能异质性的专职抗原提呈细胞,其既能启动初始免疫应答,也能负向调节免疫反应。具有负向调节免疫应答功能的树突状细胞称为调节性DC(Regulatory DC,DCreg)。DCreg在某些感染性疾病、自身免疫性疾病、肿瘤等的发生发展过程中起重要作用,也有望在临床中成为重要的治疗工具。DCreg的分化与细胞所处的微环境有关,结合微环境研究DCreg才能客观地反应机体免疫功能的真实状态。本文就DCreg分化的微环境、血管活性肠肽(Vasoactive intestinal peptide,VIP)诱导的DCreg(DCVIP)以及部分DCreg在免疫相关性疾病中的临床意义等方面的最新研究进展作一综述。     

微环境温湿度智能化测量仪研究

研究了微环境温湿度在线精密测量系统。该系统由传感器、下位机和接口组成 ,具有多点位测量、大容量数据存储、数据掉电保护、自动时钟和与 PC机通讯等多项智能化功能。还研究了微环境中温湿度传感器的结构和标定方法以及相关的技术难点及其解决方案     

Contaminant dispersion with personal displacement ventilation,Part I: Base case study

Personal displacement ventilation (PDV) is a new ventilation concept that combines the positive features of displacement ventilation with those of task conditioning or personalized ventilation. PDV is expected to create a micro-environment around an occupant to control the environment individually. In this study, a base PDV case with a contaminant source at different locations was modeled for contaminant dispersion in a full-scale chamber. Computational fluid dynamics (CFD) was used to simulate the indoor airflow and pollutant transport, and the simulation results were validated against the experimental data. The contaminant concentration field for three different contaminant source locations was analyzed. Based on our results, it seems that this kind of PDV system cannot create the expected “micro-environment” to avoid the disturbance of the outside airflow. Further studies on how to improve the PDV performance are given in the companion paper.     

农田水势软测量中的辅助变量选择与数据预处理

连续自动监测土壤-植物-大气连续体中的水势并据此了解农作物水分胁迫状态是真正精准灌溉（PI）的重要前提。鉴于作物活体水势自动监测较为困难,提出基于作物活体微环境信息的软测量技术。基于SPAC水分传输机理和作物微环境数据特征分析,选择若干种易测微环境信息软测量的辅助变量;数据预处理则采用了聚类分析等新方法,在侦测异常数据和滤除随机噪声方面取得了良好的效果。     

Measuring accident risk exposure for pedestrians in different micro-environments

Pedestrians are mainly exposed to the risk of road accident when crossing a road in urban areas. Traditionally in the road safety field, the risk of accident for pedestrian is estimated as a rate of accident involvement per unit of time spent on the road network. The objective of this research is to develop an approach of accident risk based on the concept of risk exposure used in environmental epidemiology, such as in the case of exposure to pollutants. This type of indicator would be useful for comparing the effects of urban transportation policy scenarios on pedestrian safety. The first step is to create an indicator of pedestrians’ exposure, which is based on motorised vehicles’ “concentration” by lane and also takes account of traffic speed and time spent to cross. This is applied to two specific micro-environments: junctions and mid-block locations. A model of pedestrians’ crossing behaviour along a trip is then developed, based on a hierarchical choice between junctions and mid-block locations and taking account of origin and destination, traffic characteristics and pedestrian facilities. Finally, a complete framework is produced for modelling pedestrians’ exposure in the light of their crossing behaviour. The feasibility of this approach is demonstrated on an artificial network and a first set of results is obtained from the validation of the models in observational studies.     

基于BIM的北京路及周边地区城市规划微环境模拟

在人们日益重视生态环境的今天,如何在城市规划过程中融入城市生态学是规划学者越来越重视的问题。本文以广州市北京路沿线微环境模拟这一实例, 阐述了微环境生态模拟在城市设计过程中的作用,并对其技术方法进行了探讨。