含气率对小流量下混流式混输泵轴系振动的影响

振动是反映混输泵运行稳定性的关键指标,液体含气率对混输泵的振动强度有重要影响.为探究小流量工况下含气率变化对混输泵轴系振动的影响规律,该研究以某3级混流式气液混输泵为研究对象,采用建立的多通道振动测试系统采集小流量工况下混输泵输送不同含气率的水时主轴和轴承座的振动信号,然后分析水中含气率对主轴和轴承座振动特性的影响规律...     

固体燃料导致室内空气污染的研究动态及热点——基于文献计量学分析

室内燃用煤炭和生物质等固体燃料会造成严重的室内空气污染,全球每年约数百万过早死亡可归因于室内固体燃料燃烧排放的PM2.5暴露。为分析固体燃料使用导致室内空气污染的研究进展和发展趋势,采用文献计量学软件CiteSpace对Web of Science核心数据集（Core Collection）中的相关文献进行了知识网络结构的挖掘,讨论了发文数量、期刊、关键词等的特征及变化趋势,重点探讨了该领域研究的发展过程和热点。结果表明,领域内相关研究的发文量呈指数上升趋势,说明该问题受到越来越多的关注。很多研究发表在Indoor Air、Science of the Total Environment、Energy for Sustainable Development等专业或综合类环境期刊。来自美国和中国的研究团队发文量居前列。清洁炉灶、清洁能源、黑碳和PM2.5是领域研究中较常涉及的关键词。污染暴露的健康危害、清洁干预、健康和气候共同效益是今后值得重点关注的方向。建议围绕“污染-暴露-健康风险”的过程链,开展系列研究以支撑相关人群健康保护。     

不同类型梅花品种及近缘种山桃挥发性成分分析

[目的]研究不同类型梅花品种及山桃花朵挥发性成分的差异。[方法]采用顶空-固相微萃取与气相色谱-质谱联用技术对梅花品种青岛朱砂、黑美人、丰后、淡丰后、燕杏梅和山桃花朵挥发性成分进行分析。[结果]从几种植物中共鉴定出20种挥发物。不同类型梅花品种及山桃植物花朵挥发物数量和含量有很大的变化,苯基/苯丙烷类芳香族的化合物含量占有绝对的优势,其中苯甲醛、苯甲醇和乙酸苯甲酯等是梅花及山桃花朵挥发物的主要成分,出现的频率高达100%。[结论]为开发利用梅花香气资源和花香育种提供了科学依据。     

Influence of fertilization and organic amendments on organic‐carbon fractions in Heilu soil on the loess plateau of China

The influence of fertilization on organic‐carbon fractions separated by density and particle size in Heilu soil (Calcic Kastanozems, FAO) was investigated in a 20‐year (1979–1999) long‐term experiment on the Loess Plateau of China. Compared to an unfertilized treatment, N application alone did not increase total organic carbon (TOC) and its fractions of density and particle size. However, the treatment of N + P fertilization significantly increased salty‐solution–soluble organic carbon (SSOC), microbial biomass C (MB‐C), and organic C associated with fine silt. When manure was applied alone and in combination with N and P fertilizer, the light fraction of organic C (LFOC), SSOC, and MB‐C were increased significantly, and the TOC was as high as that of a native Heilu soil. Organic C associated with different particle‐size fractions was also increased significantly, and the allocation of C among the fractions was altered: the proportions of C in sand (>50 μm), coarse‐silt (20–50 μm), and fine‐clay (<0.2 μm) fractions were increased whereas fine‐silt (2–20 μm) and coarse‐clay (0.2–2 μm) fractions were decreased. It is concluded that N fertilizer alone is not capable of restoring organic‐matter content in the Heilu soils of the Loess Plateau and that C‐containing material like manure and straw is necessary to produce significant increase in soil organic carbon in these soils.     

固相微萃取技术及其应用

固相微萃取(SolidPhasemicroextraction,SPME)技术是近年来发展起来的一种样品分析预处理的新方法,该技术集采样、萃取、浓缩和进样于一体,简便、快速、经济安全、无溶剂、选择性好、且灵敏度高。文章介绍了固相微萃取的装置、原理、操作及萃取方法,着重论述了其工作条件选择,包括不同涂层的萃取头、萃取时间、萃取温度、搅拌方法、萃取方式、离子强度等因素对固相微萃取的萃取效率的影响,此外文章还指出固相微萃取技术已经广泛的应用于医药、环境、食品等生活领域。     

固相萃取-高效液相色谱串联质谱法测定油菜薹中反式维生素K1含量

为准确测定反式维生素K1的含量,建立了基于固相萃取-高效液相色谱串联质谱的甘蓝型油菜（Brassica napus L.）菜薹反式维生素K1高灵敏检测技术。样品经正己烷提取、中性氧化铝柱净化后,用C30反相色谱柱,以甲醇 （含0.025%甲酸+2.5 mmol/L甲酸铵）为流动相,采用选择反应监测（selected reaction monitoring, SRM）模式进行定量分析,20 min内可实现顺反异构体色谱分离。方法学考察结果显示,反式维生素K1在范围内线性关系良好,相关系数为0.9985。该方法检出限为0.29 μg/kg,定量限为0.95 μg/kg。回收率为87.5%～117.6%,精密度（RSD）在0.72% ～9.59%之间。利用该方法对油菜薹和反式维生素K1含量高的3种蔬菜进行分析,发现油菜薹中反式维生素K1含量为340.08 μg/100g,高于小白菜（B. rapa spp. chinensis,260.93 μg/100g）、西兰花（B. oleracea var. Italic Planch, 167.65 μg/100g）和结球甘蓝（B. oleracea var. capitata,151.11 μg/100g）。本文建立的蔬菜中反式维生素K1准确定量分析方法操作简单、灵敏度高、结果准确。同时比较发现油菜薹是一种富含维生素K1的蔬菜。      

中国亚热带两种竹林凋落物输入量、凋落物分解和养分释放动态

Bamboos are one of the fast-growing and multiple use species in the world, and thus bamboo forests/plantations play an important role in C sequestration at regional and global levels. We studied aboveground litterfall, litter decomposition and nutrient dynamics for two years in two subtropical bamboo ecosystems in Southwest China so as to test the hypothesis that litter quality determine the rate and nutrient dynamics during decomposition of different litter fractions. Mean annual total aboveground litter production ranged from 494 to 434 g m-2 in two bamboo stands （P stand, dominated by Pleioblastus amarus and H stand, hybrid bamboo dominated by Bambusa pervariabilis x Dendrocalamopsis daii）. Bulk （-80%） of litter production was contributed by leaf litter in two stands followed by twigs and sheathes. Different litter fractions represented considerable variations in the rates of mass loss and nutrient release. Variation of the mass remaining after 2 years of decomposition was significantly explained by initial C/N ratio and initial P concentration. Initial concentrations of N, P, Ca, and Mg explained 57.9%, 95.0%, 99.8% and 98.1%, respectively, of the variations of these elements mass remaining after 2 years of decomposition. The patterns of nutrient dynamics and the final amount remaining were mainly determined by their initial litter substrate quality in tl~ese two subtropical bamboo plantations.     

Model calculations of water dynamics in lysimeters filled with granular industrial wastes

A three‐year long lysimeter experiment with a fine‐grained aluminum (Al) recycling by‐product and a mixture of this by‐product and a coal combustion waste was conducted. The wastes were proposed as possible soil substitutes in an engineered surface barrier covering a potash mining residue mount. To evaluate the suitability of the wastes as surface barrier material, their hydrological behavior under field conditions must be known. Lysimeter experiments provide one means to study the hydrological behavior of soils or soil‐like materials. However, it is difficult to estimate the long‐term hydrological behavior from short‐term lysimeter studies. The present study was conducted therefore to derive from short‐term lysimeter observations the long‐term hydrological behavior of the two waste materials. The lysimeter data were used to calibrate the one‐dimensional soil water flow model HYDRUS‐1D. With the calibrated model, hydrological simulations for the site of the residue mount were carried out for a period of 31 yr. Calculated long‐term annual seepage from the lysimeters was 237 mm for the pure Al waste and 186 mm for the mixture, or 39% and 24% of the average annual precipitation (764 mm). The average discharge of the bare mount is 482 mm or 63%. We conclude that a soil cover could considerably reduce the discharge and that the mixture is better suited as surface barrier than the pure Al waste.     

固态热带假丝酵母菌菌剂的发酵工艺研究

试验在单因素优化试验的基础上,采用正交试验进一步对热带假丝酵母菌固态发酵工艺进行研究,包括发酵时间、接种量、料水比、碳源、氮源、无机盐等因素,最终确定热带假丝酵母菌的固态发酵工艺。发酵条件:在自然pH值条件下,发酵温度30℃、发酵时间48 h、接种量11%、料水比1∶0.75。培养基成分:麸皮与甘油8.5∶1.5 (g/g)、尿素0.5%、磷酸二氢钾0。依照此工艺进行发酵,热带假丝酵母菌活菌数最高可达32.94×10⁸个/g。     

优良生防枯草芽孢杆菌CY1固态发酵研制生物有机肥工艺参数优化

枯草芽孢杆菌CY1是一株广谱性的根际促生菌,为促进农业废弃物的资源化利用,提高固态发酵生产生物有机肥过程中枯草芽孢杆菌CY1的扩繁能力,研究采用猪粪堆肥为原料,麸皮、豆粕、玉米粉为辅料进行固态发酵研制新型生物有机肥,以有效活菌数为参考指标,确定原料、辅料最佳配比及接种量。选用Plackett-Burman试验设计对影响发酵的8个因素进行效应评价,筛选出具有显著效应的3个因素：初始pH、发酵温度及含水量。用最陡爬坡试验逼近最大响应区域,通过响应面分析法确定最优发酵工艺参数。结果表明,固态发酵条件为初始pH 7.51、KH₂PO₄含量0.75%、MgSO₄含量0.15%、MnSO₄含量0.15%、发酵温度36.10℃、葡萄糖含量6.00%、(NH₄)₂SO₄含量0.75%、含水量26.33%,此时固态发酵产物有效活菌数最大,达到4.57×10¹⁰ CFU·g^-1。该研究为利用农业废弃物采用合适的...