基于赤泥载氧体的蓝藻化学链热解和气化特性研究

本研究以高挥发分的蓝藻成型颗粒为对象,采用赤泥作为载氧体,开展蓝藻化学链热解和气化特性研究,考察赤泥载氧体对热解和气化行为的影响规律.基于流化床反应器,研究了不同温度(750-900℃)和不同比氧耗(0.1-0.7)下蓝藻成型颗粒化学链热解和气化过程中合成气组分分布、碳转化率和速率、有效合成气组分和合成气中H2/CO的...     

鲁西南沿黄县区玉米中铅、镉、砷、铬重金属的含量及健康风险评价

为了评估鲁西南沿黄县区(东明县、牡丹区、鄄城县、郓城县)玉米中铅、镉、砷、铬重金属的污染风险,采集该地区玉米果穗,利用电感耦合等离子体质谱(ICP-MS)仪测定其玉米籽粒中铅、镉、砷、铬的含量,并使用单因子污染指数法、内梅罗综合多因子指数法和目标危险系数法开展玉米籽粒重金属污染评价和健康风险评价。结果表明,鲁西南沿黄县区玉米籽粒中重金属铅、镉、砷、铬的含量均未超出GB 2762—2017中规定的限量,重金属含量以Cr最高;鲁西南沿黄县区P_综和TTHQ均小于1,说明玉米籽粒中的重金属元素含量为清洁安全等级,食用该地区玉米对人体的健康风险较低。     

高耐热PLLA/PDLA共混物的热性能和结晶结构研究

通过熔融共混法制备了一系列等比例聚左旋乳酸(PLLA)/聚右旋乳酸(PDLA)共混试样,采用差示扫描量热法(DSC)、核磁共振(13C-NMR)及广角X射线衍射(WAXD)等方法对共混产物进行了表征和研究分析.结果表明,等比例PLLA和PDLA熔融共混生成了立构复合物(stereocomplex,sc),同时部分均聚物发生酯交换反应,生成了立体嵌段物(stereoblock,sb),从而在DSC升温曲线上sc晶体处出现特殊的熔融双峰现象;随着熔融共混温度升高,sc晶体的生成率和结晶度逐渐下降;聚乳酸立构复合物的加工稳定性较好,二次加工后,sc晶体熔点基本不变,生成率和结晶度提高;由于sc晶体的存在,PLLA/PDLA共混物的耐热性能提高,退火热处理后耐热性能得到进一步提高.这对于开发高耐热聚乳酸及其加工应用具有重要的应用价值.     

毛细管电泳-紫外检测法同时测定食品中的葡萄糖和多种糖醇

建立了食品中葡萄糖、半乳糖醇、甘露醇、山梨醇、赤藓糖醇、木糖醇和麦芽糖醇的毛细管电泳-紫外检测同时测定方法。食品中的葡萄糖和糖醇在硼砂碱性介质中与硼酸根结合形成阴离子配合物后,在添加了电渗流改性剂十六烷基三甲基溴化铵的硼砂缓冲液(pH 9.2)中进行快速电泳分离,紫外检测器于195 nm处检测。在优化的条件下,7种物质在12 min内基线分离,标准曲线线性良好(r>0.999),检出限均低于0.1g/L,加标回收率为81.6%~120%,相对标准偏差(RSD)小于6%。方法适用于食品中葡萄糖和多种常见糖醇的同时检测。     

电感耦合等离子体质谱法同时测定地质样品中镉、锗、钴

建立电感耦合等离子体质谱法同时测定地质样品中镉、锗、钴含量的分析方法。样品用氢氟酸-硝酸混合溶液加热溶解,然后加热浓缩驱酸,再用硝酸溶液(1+1)复溶提取,在选定的仪器工作条件下进行测定。镉、锗、钴的含量分别在0.00~0.10,0.00~5.00,0.00~50.00 μg/g范围内与质谱峰强度呈良好的线性关系,相关系数均大于0.999,方法检出限分别为0.01,0.02,0.02 μg/g。用该方法对国家一级标准物质进行测定,测定值的相对误差均小于10%,测定结果的相对标准偏差为0.79%~8.45%(n=12)。该方法样品处理过程简便,检测效率高,适用于批量地质样品中镉、锗、钴的测定。     

Specific heat ratio effects of compressible Rayleigh–Taylor instability studied by discrete Boltzmann method

Rayleigh–Taylor (RT) instability widely exists in nature and engineering fields. How to better understand the physical mechanism of RT instability is of great theoretical significance and practical value. At present, abundant results of RT instability have been obtained by traditional macroscopic methods. However, research on the thermodynamic non-equilibrium (TNE) effects in the process of system evolution is relatively scarce. In this paper, the discrete Boltzmann method based on non-equilibrium statistical physics is utilized to study the effects of the specific heat ratio on compressible RT instability. The evolution process of the compressible RT system with different specific heat ratios can be analyzed by the temperature gradient and the proportion of the non-equilibrium region. Firstly, as a result of the competition between the macroscopic magnitude gradient and the non-equilibrium region, the average TNE intensity first increases and then reduces, and it increases with the specific heat ratio decreasing; the specific heat ratio has the same effect on the global strength of the viscous stress tensor. Secondly, the moment when the total temperature gradient in y direction deviates from the fixed value can be regarded as a physical criterion for judging the formation of the vortex structure. Thirdly, under the competition between the temperature gradients and the contact area of the two fluids, the average intensity of the non-equilibrium quantity related to the heat flux shows diversity, and the influence of the specific heat ratio is also quite remarkable.     

低温密闭碱熔–电感耦合等离子体发射光谱法测定岩石矿物中二氧化硅

建立电感耦合等离子体发射光谱法测定岩石矿物样品中二氧化硅含量的方法.在防腐高压消解罐中,用氢氧化钠低温消解样品,以盐酸浸提,采用电感耦合等离子体发射光谱法进行测定.二氧化硅的质量浓度在0～50μg/mL范围内与光谱发射强度线性关系良好,线性相关系数为0.9998,检出限为0.45％.用该方法对国家一级标准物质进行测定,...     

Influence of annealing conditions on impurity species in arsenic-doped HgCdTe grown by molecular beam epitaxy

Based on our previous work,the influence of annealing conditions on impurity species in in-situ arsenic (As)-doped Hg 1 x Cd x Te (x ≈ 0.3) grown by molecular beam epitaxy has been systematically investigated by modulated photoluminescence spectra.The results show that (i) the doped-As acting as undesirable shallow/deep levels in as-grown can be optimized under proper annealing conditions and the physical mechanism of the disadvantage of high activation temperature,commonly assumed to be more favourable for As activation,has been discussed as compared with the reports in the As-implanted HgCdTe epilayers (x ≈ 0.39),(ii) the density of V Hg has an evident effect on the determination of bandgap (or composition) of epilayers and the excessive introduction of V Hg will lead to a short-wavelength shift of epilayers,and (iii) the V Hg prefers forming the V Hg-As Hg complex when the inactivated-As (As Hg or related) coexists in a certain density,which makes it difficult to annihilate V Hg in As-doped epilayers.As a result,the bandedge electronic structures of epilayers under different conditions have been drawn as a brief guideline for preparing extrinsic p-type epilayers or related devices.     

高性能混凝土添加剂在桥梁工程中的成本效益分析

<正>高性能混凝土融合了高强度、高耐久性、优良的体积稳定性、易混合性、易施工性和抗渗性,成为一种高级建筑材料。其组成精心挑选,确保最佳性能。主要包括：优质硅酸盐水泥作为基础,确保强度和耐久性;细粒度沙子作为精细骨料,增强密实性;碎石或碎砾作为粗骨料,提升结构强度;严格控制的水用量,以维持理想的水泥比例;矿物掺合料如硅灰、粉煤灰或矿渣,以提高强度和环保性能;     

膜富集固相萃取-漫反射光谱法快速测定食品中柠檬黄北大核心CSCD

色素作为食品中常用的添加剂,近年来受到广泛关注。人工合成色素通常较天然色素色彩鲜艳、坚牢度大、稳定性强、价格低廉,所以有着广泛的应用[1]。柠檬黄是人工合成黄色素中具有代表性的一种,其为橙黄色均匀粉末,可溶于水,耐热性、耐光性等均好,被广泛用于饮料、固体食品中,但柠檬黄分子中含有苯环等结构,具有毒性,食品中最大使用量为100 mg·L-1[2]。因此,检测饮料中柠檬黄十分重要。