Distribution of polycyclic aromatic hydrocarbons in snow of Mount Nanshan,Xinjiang

Polycyclic aromatic hydrocarbon (PAH) in snow samples collected from Mount Nanshan (Xinjiang, China) was investigated for eight stations. Fourteen PAHs were detected in these samples. The total PAH concentration ranged from 70.15 ng/L to 155.67 ng/L, with an average of 113.02 ng/L. Human carcinogens, such as fluoranthene, chrysene, benzo(a)pyrene, dibenzo(a,h)anthracene, indeno(1,2,3‐cd)pyrene and benzo(ghi)perylene in snow were assessed based on risk quotient. Preliminary assessment showed that these PAHs posed a moderate risk. Component analysis showed that the PAHs found in the snow samples were mainly three‐ring PAHs, which comprised 34.51–90.81% of the total PAHs. Phenanthrene, fluorene and anthracene accounted for 35.08, 11.90 and 11.13% of the total PAHs, respectively. The ΣPAH content increased with the increasing altitude, and the highest concentration of 155.67 ng/L was observed in snow samples from the N7 station, which was located near the top of the mountain. This high PAH concentration in N7 was possibly due to more frequent human activities in the area and long‐distance transportation of PAHs. Isomer ratios were used to determine the possible sources of PAHs in the samples. The results indicate that coal and biomass combustion made a larger contribution than emissions from petroleum consumption. It is therefore of utmost importance to develop new fuels taking the place of coal and to achieve as complete as possible for the burning of carbon‐containing materials.     

基于水资源优化配置多目标决策模型探析

水资源优化配置问题是一个多目标决策问题,该文在分析水资源优化配置基本概念及内涵的基础上,依据水资源配置的原则及目标,对基于经济目标、环境目标与社会目标的水资源优化配置多目标决策模型进行了较为深入的分析,并探讨了模型的求解及决策方案的选择,可为水资源优化配置多目标决策问题提供一定的理论和实践指导。     

鸡蛋高温贮藏下脂质变化及酶活相关性研究

本研究通过考察鸡蛋高温贮藏(37℃)条件下脂质组分变化、脂肪酶活性变化及氧化指标的变化,并借助相关性分析阐释酶活变化与脂质氧化的内在联系。实验结果表明:贮藏过程中鸡蛋失重率、蛋黄p H、蛋黄水分含量显著增加而蛋黄指数和哈弗单位(HU)显著下降(p0.05);37℃贮藏15 d后,总脂质含量由于水分迁移而呈现下降趋势(从28.93 g/100 g降至24.20 g/100 g),磷脂含量显著降低(45.55 g/100 g降至34.37 g/100 g脂质)而游离脂肪酸显著增加(1.24 g/100 g增至3.67 g/100 g脂质),与脂质变化相关的中性脂肪酶、酸性脂肪酶及磷脂酶至贮藏结束活力分别下降76.50%、56.78%、56.81%。磷脂组分中的磷脂酰胆碱(Phosphatidylcholine,PC)、磷脂酰乙醇胺(Phosphatidyl ethanolamine,PE)、磷脂酰肌醇(Phosphatidylinositol,PI)在贮藏过程中也呈现含量显著下降的趋势而过氧化值(Peroxide value,POV)、硫代巴比妥酸值(Thiobarbituric Acid Reactive Substances,TBARS)呈现显著升高。相关性分析证明脂质组分变化与酶活变化显著相关。本研究说明鸡蛋贮藏中脂质会发生明显的水解及氧化,这些变化在一定程度上由酶促氧化造成。     

梅奇酵母氨基甲酸乙酯酶分离纯化与酶学性质分析及其对葡萄酒香气的影响

为了研究梅奇酵母所产生氨基甲酸乙酯（Ethyl Carbamate,EC）酶的性质,通过硫酸铵盐析、离子交换层析的方法对EC酶进行分离纯化,并对纯化后EC酶的酶学性质进行了分析。结果表明,纯化后EC酶对比纯化前的酶活提高了约1.2倍。纯化后EC酶最适反应温度为35 ℃,在25~45 ℃之间热稳定性较强;最适pH为5.5,在pH5~6时该酶稳定性强,即酸稳定性强,碱稳定性较差。当乙醇体积分数为12%~14%时,EC酶具有一定酶活。底物特异性结果表明,该EC酶对EC及其前体物质（尿素）具有较高的降解能力,且对于成品葡萄酒挥发性香气成分影响不显著。     

新疆传统乳品中乳酸菌的抗氧化能力

实验用菌为从新疆传统乳制品酸奶和干酪中分离出的7株乳酸菌,分别是乳酸片球菌(Pediococcus acidilactici)1株、植物乳杆菌(Lactobacillus plantarum)3株、耐久肠球菌(Enterococcus durans)1株、魏斯氏菌(Weissella cibaria)1株和面包乳杆菌(Lactobacillus panis)1株。对其清除DPPH自由基、超氧阴离子自由基、羟自由基、还原能力以及亚铁离子螯合能力进行了研究。结果表明:7株乳酸菌具有不同的抗氧化能力,其中植物乳杆菌亚铁离子螯合能力最强,乳酸片球菌超氧阴离子自由基清除能力相对较高,魏斯氏菌的DPPH自由基清除能力较强,面包乳杆菌的羟自由基清除能力和还原能力最强。     

基于感压胶片测量技术的苹果静压接触应力及损伤分析

采用Prescale感压胶片测量苹果静压接触应力的分布特性,并结合图像处理技术对褐变区域进行精确测量,以明确应力面积与损伤面积之间的关系,了解苹果损伤发生的机制。结果表明,苹果果肉出现酶促褐变损伤的应力为0.29 MPa;0.20~0.40 MPa的应力分布占72%,构成苹果损伤的主要区域;苹果的损伤面积与应力均值无直接关系;应力总面积高出苹果损伤面积9%,只有≥0.10MPa应力面积最接近苹果损伤面积,用其估测损伤面积的平均误差仅为1.66%,两者之间的关系可表示为A=0.98AP≥0.10+1.95。     

新疆西伯利亚白刺果中红色素的提取工艺

以溶剂浓度、浸提时间、pH值为因素，各设3个水平，按L9（34）正交表设计实验，筛选白刺红色素的最佳提取工艺。结果得出采用pH1的20％乙醇，提取4次，每次0．5h效果较佳。本方法工艺简便、合理可行，适于工业化生产。     

Chemical compositional characterization of eight pear cultivars grown in China

The sugar, organic acid, amino acid and fatty acid compounds of eight commercial pear cultivars were identified and quantified using high-performance liquid chromatography (HPLC) equipped with RI and UV detectors and gas-chromatography (GC) equipped with FID detector. The mineral composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed great quantitative differences in the composition of the pear cultivars. Fructose was the dominant sugar in the eight pear varieties, followed by glucose and sucrose, while malic acid was the principal organic acid. The C16:0, C18:0, C18:1, C18:2 and C18:3 fatty acids were clearly the most abundant fatty acids, and the C18 family comprised more than 70% of the total fatty acids content. Asparagine and serine were the principal amino acids. Potassium is the most abundant mineral, followed by magnesium and calcium. The results provide important information on how to make the best use of pear cultivars investigated for different uses, which is of significance for both technological research and processing practice.     

棉油皂脚中植物甾醇的提取工艺研究

为了探索从棉油皂脚中提取植物甾醇的工艺条件。以皂脚为原料,通过单因素和正交实验优化最佳工艺条件,并对粗品进行纯化,以高效液相色谱法测定的甾醇含量为考察指标。植物甾醇提取的最佳工艺为:皂化料液比1∶3,90℃下皂化3 h,用乙酸乙酯进行萃取,料液比为1∶20,粗甾醇的提取率为75.6%,其中提取得到的β-谷甾醇和菜油甾醇的纯度分别为(66.5±0.47)%、(5.67±0.08)%,其经无水乙醇重结晶两次后,纯度可达91.8%。结果表明最佳提取工艺重现性较好;HPLC法测定甾醇含量结果准确可靠。     

CO余热锅炉装置关键部件的设计及流场模拟

CO余热锅炉是催化裂化装置的关键部件,影响整套装置的安全经济运行。针对高温烟气热能浪费、环境污染等问题,设计了一种高温烟气回收装置,并对关键结构气风混合室进行三维实体建模,通过CFD前处理软件Gambit进行网格划分,最后导入Fluent软件对该结构进行数值流场模拟,结果表明该装置能够有效回收高温烟气、减少热量损耗、降低生产成本,具有很好的经济与社会效益。