Determination of vanillin in vanilla perfumes and air by capillary electrophoresis

The present study investigated capillary electrophoretic detection of vanillin in vanilla perfume and air. An UV-absorbance detector was used in a home-made capillary electrophoretic instrument. A fused silica capillary (outer diameter: 364 μm, inner diameter: 50 μm) was used as a separation capillary, and a high electric voltage (20 kV) was applied across the two ends of the capillary. Total length of the capillary was 70 cm, and the effective length was 55 cm. Experimental results showed that the vanillin peak was detected at about 600, 450, and 500 seconds when pH of running buffers in CE were 7.2, 9.3, and 11.5, respectively. The peak area of vanillin was proportional to its concentration in the range of 0–10^?2 mol/L. The detection limit was about 10^?5 mol/L. Vanillin concentration in a 1% vanilla perfume sample was determined to be about 3×10^?4 mol/L, agreed well with that obtained by a HPLC method. Furthermore, determination of vanillin in air by combination of CE and active carbon adsorption method was investigated     

京津冀与长三角区域大气NO2污染特征

基于地面监测及遥感反演数据,研究了京津冀与长三角区域大气NO2污染特征,并进行了对比分析.从2005～2011年的平均近地面质量浓度和垂直柱浓度来看,京津冀与长三角中心城市大气NO2基本处于同一污染水平;其区域背景站的NO2浓度也差异不大,且与两大区域过渡地带的合肥市大致相同.区域NO2高浓度中心夏季较为分散,秋冬季高浓度范围明显扩大,冬季全部连为一片.近年来随着中心城区污染企业的外迁,北京、上海等城市核心区NO2近地面污染有所缓解,但区域背景站NO2近地面浓度和垂直柱浓度都有所升高,京津冀与长三角NO2整体污染水平形势依旧严峻.从区域分布看,北京、上海等城市NO2浓度较高,NO2柱浓度高出区域背景的50%左右,大约是欧亚大陆背景水平的3倍;近地面NO2浓度地域差异更大,北京、上海等中心城市NO2近地面质量浓度是城市清洁区的2倍,是区域背景的10倍以上,达欧亚大陆背景站瓦里关的上千倍.北京奥运及上海世博等大型活动之前及期间大气污染集中整治效果较为明显,但活动结束后,城市大气NO2污染都出现反弹.结果表明,区域空气质量的持续改善需要区域内各省市常抓不懈的联防联控,仅靠短期内运动式的污染治理难以从根本上解决大气环境问题.     

城市大气臭氧柱浓度时空变化研究——以天水为例

城市臭氧发生发展规律的研究将为城市环境管理提供理论依据。文章利用卫星OMITO3e数据产品,解译和分析了天水市2006~2014年臭氧柱浓度的时空动态信息。结果表明:(1)空间分布呈现东北、西北高,中部、南部低的倒"V"字形;(2)年变化呈单峰曲线,从2006年至2010年为上升期,每年的增长率为3.98%,2010年至2014年为下降期,年均下降率为2.52%;(3)四季变化明显分为两个阶段,前三年为冬季春季夏季秋季;后六年以夏、春季变化为主,冬、秋季为辅,夏季春季冬季秋季。夏、春两季在第二阶段明显升高与当地经济的快速发展有密切的关系;(4)9年间臭氧柱浓度平均值为301.177 DU,最大值为325.829 DU,最小值为279.093 DU,臭氧柱浓度指示的多年空气质量等级为良好。     

分层填料土地毛管渗滤系统脱氮作用研究

对土壤煤渣分层的土地毛管渗滤系统的脱氮效果和机理进行了研究。氮的静态吸附试验和土壤全氮含量分析表明,填料对氮的去除作用有限。植物对总氮的去除贡献率只占0.47%,作用不明显。温度和总氮去除率的相关分析表明,温度对总氮去除效果影响不显著。提高出水水位30 cm以创造适合反硝化菌生长的还原环境,总氮去除率由39.1%下降到30.0%,可见氧化还原条件不是系统反硝化反应的限制条件。投加葡萄糖作为碳源,使C/N〉3,有机物去除率保持在80%以上,总氮的去除率上升到52.4%,较高的C/N比能有效提高土地毛管渗滤系统的总氮去除效果。     

Comparison of several packings for CO2 chemical absorption in a packed column

CO₂ capture and storage has gained widespread attention as an option for reducing greenhouse gas emissions. Chemical absorption and stripping of CO₂ with hot potassium carbonate (K₂CO₃) solutions has been used in the past, however potassium carbonate solutions have a low CO₂ absorption efficiency. Various techniques can be used to improve the absorption efficiency of this system with one option being the addition of promoters to the solvent and another option being an improvement in the mass transfer efficiency of the equipment. This study has focused on improving the efficiency of the packed column by replacing traditional packings with newer types of packing which have been shown to have enhanced mass transfer performance. Three different packings (Super Mini Rings (SMRs), Pall Rings and Mellapak) have been studied under atmospheric conditions in a laboratory scale column for CO₂ absorption using a 30 wt% K₂CO₃ solution. It was found that SMR packing resulted in a mass transfer coefficient approximately 20% and 30% higher than that of Mellapak and Pall Rings, respectively. Therefore, the height of packed column with SMR packing would be substantially lower than with Pall Rings or Mellapak. Meanwhile, the pressure drop using SMR was comparable to other packings while the gas flooding velocity was higher when the liquid load was above 25 kg m⁻² s⁻¹. Correlations for predicting flooding gas velocities and pressure drop were fitted to the experimental data, allowing the relevant parameters to be estimated for use in later design.     

爆炸荷载作用下方钢管混凝土柱的动力响应及破坏机理

方钢管混凝土柱是被广泛采用的组合构件之一.爆炸发生时产生的爆炸冲击波可能会对框架结构内部的方钢管混凝土拄造成严重破坏,然而目前对其动力响应及破坏机理的研究成果相对较少.本文采用有限元分析软件ANSYS/LS-DYNA对爆炸荷载作用下方钢管混凝土柱的动力响应和破坏机理进行了研究分析.建立了方钢管混凝土拄实体有限元模型,其...     

饱和砂质土壤中不同流速条件下1, 2-二氯乙烷的运移及模拟

采用室内土柱试验方法,研究了孔隙水流速对1,2-二氯乙烷(1,2-DCA)在饱和砂质土壤中运移行为的影响.借助CXTFIT模型,通过示踪剂(KBr)穿透试验,获取了土柱内部条件参数,包括弥散系数D和孔隙水流速v,以及可动水和不可动水的分配比例.应用示踪剂试验获取的参数,分别使用平衡模型和非平衡两点模型对1,2-DCA在不同孔隙水流速下的穿透曲线进行了拟合.结果表明,平衡模型不能很好地模拟本文试验条件下1,2-DCA的运移,而非平衡两点模型拟合精度较高.试验条件下,流速对1,2-DCA运移影响显著.孔隙水流速较高时穿透时间较短,穿透曲线峰值更高.土壤对1,2-DCA的吸附作用是影响穿透特征的主要因素,高流速条件下,吸附作用的影响较小.     

Dredged Material Disposal at the Edge of the Florida Current

A field data collection project was undertaken to investigate the short-term fate of dredged material discharged in the designated Miami Ocean Dredged Material Disposal Site (ODMDS) before dredging of the Miami River and the Miami Harbor Turning Basin begins. the designated ODMDS is located in relatively deep water for discharge sites with a typical bottom depth of 150 metres and is also located in the western boundary region of the Gulf Stream current off Miami. Acoustical backscattering, current, particulate, temperature and salinity data were gathered over a three day period from April 24, 1990 through April 26, 1990. the major generic features of shallow-water discharge plumes were observed to be present: (a) the presence of a rapid convective descending plume portion; (b) impact of that plume portion with the ocean bottom and concomitant generation of a bottom surge; (c) rapid horizontal width growth of the descending plume through entrainment; and (d) retention of a residual plume portion within the water column. A well-mixed upper water column layer extending to a depth of 40 to 60 metres below the surface of the ocean permitted measurements of the plume entrainment coefficient free from bottom boundary, water column density gradient, and vertical current shear effects which are usually present in relatively shallow, e.g. less than 40 metres bottom depth, coastal ocean discharge studies. Entrainment coefficient estimates obtained in this study were between 0.5 to 0.7. the residual water plume material was tracked over one-half hour during each of eight discharge events and was transported in a north-northeast direction.     

TBP柱填料萃取回收铁钍渣浸出液中钍的研究

将ＴＢＰ固定于多孔载体上，用于萃取硝酸水溶液中的钍。实验表明，萃取分配比高，萃取容量大，能有效地防止乳化现象。将ＴＢＰ柱填料制备成填充柱，对含Ｔｈ＾４＋，Ｆｅ＾３＋和Ｃｅ＾３＋的铁钍渣浸出液进行萃取实验得出：当溶液硝酸浓度为４ｍｏｌ／ｌ，接触时间为１０ｍｉｎ时，萃余液中Ｔｈ＾４＋浓度粘于０．０１ｍｇ／ｌ。１ｇＴＢＰ柱填料可萃取的０．２５ｇ，反萃液中钍浓度为６２．５ｇ／ｌ，Ｆｅ＾３＋和Ｃｅ＾３＋的含     

基于OMI数据研究中国对流层甲醛时空分布特征及变化趋势

利用OMI卫星遥感反演的甲醛柱浓度数据,结合MEGAN模式和MEIC排放清单研究了2005—2016年中国对流层甲醛柱浓度的时空特征和长期变化趋势,以及甲醛柱浓度的季节差异与排放源和地面风场的关系.结果表明,中国对流层甲醛柱浓度呈西低东高的空间分布特征,且高值区域主要分布在华北平原、长江三角洲、珠江三角洲及四川盆地等人为源排放较高的中东部地区.中国甲醛柱浓度存在明显的季节差异,表现为夏季秋季春季冬季.天然源VOCs和人为源VOCs排放均对甲醛柱浓度季节变化具有重要影响,光化学反应与气象条件在其中所起到的作用也不可忽略.生物源排放变化对甲醛年际变化趋势的影响不显著,中国东部地区甲醛柱浓度呈上升趋势主要是由于气候变率和人为因素的共同影响所致.