Glial fibrillary acidic protein in amniotic fluids from pregnancies with fetal neural tube defects

The glial fibrillary acidic protein (GFAP) is the subunit protein of intermediate filaments in astrocytes and closely related cell types. By means of an enzyme immunoassay we have determined the concentration of GFAP in amniotic fluids from normal pregnancies and from pregnancies complicated by various fetal malformations. The group of 20 cases of fetal anencephaly had a significantly higher mean amniotic fluid GFAP concentration (115 μg/1±133.6 (S.D.), range 6–378 μg/1) than the control group of 117 normal pregnancies (13 μg/1k±5.5 (S.D.), range 0–31 μg/1), (P<0.001). Two cases of fetal encephalocele likewise had very high amniotic fluid GFAP concentrations. None of the other cases of fetal malformations investigated, including 12 cases of spina bifida, had increased amniotic fluid GFAP concentrations. We conclude that determination of the amniotic fluid GFAP concentration may give additional information in the prenatal diagnosis of fetal nervous system malformations.     

Extraction of copper ions by supercritical carbon dioxide

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The maximum power principle: An empirical investigation

The maximum power principle is a potential guide to understanding the patterns and processes of ecosystem development and sustainability. The principle predicts the selective persistence of ecosystem designs that capture a previously untapped energy source. This hypothesis was investigated empirically in controlled and replicated tests conducted in planktonic microcosms. Microecosystems that developed under a pH-controlled light regime, in which light duration was altered based on changes in an ecosystem-controllable variable (water column pH), were compared with those that developed under fixed photoperiods. According to the principle, pH-decreasing (and power-increasing) organization should selectively persist under pH-controlled light. To assess changes in pH dynamics that occurred under the alternative selection regime, in which photoperiods were not linked with pH-affecting selection or organization, the microecosystems that developed under fixed photoperiods were subjected to pH-controlled light on the last day of each test. The daily light duration increased 506 min on average in microecosystems that developed under pH-controlled light and 412 min on average in microecosystems that developed under fixed photoperiods. Selective reinforcement of acid-secreting blue-green algae in response to CO₂ and nutrient limitations could account for the greater increase in power acquisition in microecosystems that developed under pH-controlled light.     

Developing a CFD heat transfer model for applying high expansion foam in an LNG spill

Liquefied natural gas (LNG) is widely used to cost-effectively store and transport natural gas. However, a spill of LNG can create a vapor cloud, which can potentially cause fire and explosion. High expansion (HEX) foam is recommended by the NFPA 11 to mitigate the vapor hazard and control LNG pool fire. In this study, the parameters that affect HEX foam performance were examined using lab-scale testing of foam temperature profile and computational fluid dynamics (CFD) modeling of heat transfer in vapor channels. A heat transfer model using ANSYS Fluent® was developed to estimate the minimum HEX foam height that allows the vapors from LNG spillage to disperse rapidly. We also performed a sensitivity analysis on the effect of the vaporization rate, the diameter of the vapor channel, and the heat transfer coefficient on the required minimum height of the HEX foam. It can be observed that at least 1.2 m of HEX foam in height are needed to achieve risk mitigation in a typical situation. The simulation results can be used not only for understanding the heat transfer mechanisms when applying HEX foam but also for suggesting to the LNG facility operator how much HEX foam they need for effective risk mitigation under different conditions.     

LES – DFSD modelling of vented hydrogen explosions in a small-scale combustion chamber

Accidental explosions are a plausible danger to the chemical process industries. In the event of a gas explosion, any obstacles placed within the path of the flame generate turbulence, which accelerates the transient flame and raises explosion overpressure, posing a safety hazard. This paper presents numerical studies using an in-house computational fluid dynamics (CFD) model for lean premixed hydrogen/air flame propagations with an equivalence ratio of 0.7. A laboratory-scale combustion chamber is used with repeated solid obstacles. The transient compressible large eddy simulation (LES) modelling technique combined with a dynamic flame surface density (DFSD) combustion model is used to carry out the numerical simulations in three-dimensional space. The study presented uses eight different baffle configurations with two solid obstructions, which have area blockage ratios of 0.24 and 0.5. The flame speed, maximum rate of pressure-rise as well as peak overpressure magnitude and timing are presented and discussed. Numerical results are validated against available published experimental data. It is concluded that, increasing the solid obstacle area blockage ratio and the number of consecutive baffles results in a raised maximum rate of pressure rise, higher peak explosion overpressure and faster flame propagation. Future model development would require more experimental data, probably in a more congested configuration.     

煤吸附硫化氢混合气体的试验研究*

为研究煤层硫化氢（H2S）吸附特性,厘清煤层H2S赋存规律及改善H2S防治效果,采用分压测试法研究煤对H2S的吸附规律。以山西保利铁新煤业有限公司9#煤为研究对象,分别使用N2,He/H2S,N2/H2S为吸附介质开展等温吸附试验,分析煤对H2S及含H2S混合气体的吸附特性及影响因素。结果表明:煤对H2S的吸附量随压力升高而增加,随温度升高而降低,且温度对煤吸附H2S吸附量影响较大;H2S及N2/H2S混合气体的吸附曲线均符合Langmuir吸附模型,煤吸附N2/H2S混合气体时,H2S和N2存在竞争吸附,且N2吸附能力优于H2S;等温条件下,N2竞争吸附量随吸附压力的增加而增大,等压条件下,N2的竞争吸附量受温度影响较小。     

石化工业园区区域环境风险后评价的风险识别

松花江污染事故发生后,国家更加重视对已有石化工业园区的风险排查以及事故预防,风险识别是风险评价与管理的基础。通过查阅相关资料以及类比分析,分析了已有区域风险识别与普通风险识别的不同,探讨了识别的原则和重点,指出了识别的程序和相应的方法,并给出了实例论证,为区域环境风险识别研究提供借鉴。     

磁流体在印染废水处理中的应用研究

随着工业的迅速发展,大量工业废水的排放给人类生存造成了严重的威胁,尤其是印染废水,因此寻求有效的处理方法是亟待解决的问题。一种新的印染废水处理技术——应用磁流体来处理印染废水,分别研究了Fe3O4磁流体在不同条件（如pH值、表面活性剂的投加量、搅拌时间、温度等）下,对降低印染废水的COD和色度两个方面的影响。实验表明当pH=11,表面活性剂量是亚铁量的0.16倍,磁流体与废水的比大于1：10时COD降低最多,脱色效果最好。     

生态学原理在城市改造中的应用——以天津市为例

随着中国城市化进程的加快,城市改造的速度也在加快,但是由于缺少科学的理论指导,城市改造往往表现为盲目的重建。天津市在城市的改造中,以生态学原理指导城市改造,注重城市景观多样性的保护和发展,成功地对部分城区进行了改造。对城市改造应遵循的生态学理念进行了阐述,并指出,生态学原理的运用是解决目前中国城市改造中存在的问题的有效途径;并结合天津市“五大道”和海河改造的实例说明生态学原理在城市改造中的应用。     

大气扩散计算流体力学模型综合评估方法研究

模型评估方法研究是模型研发工作的重要组成部分。基于科学性验证与统计性确认提出了大气扩散CFD模型的综合确认评估方法,通过示例的方式展示了方法的使用效果。综合确认评估方法可以提高模型筛选的速度,降低统计性评估对确认性试验数据的需求量,从总体上提高模型确认的效率。评估理论的研究有助于提高基于模型的大气扩散研究的准确性,也有利于高精度模型和试验的设计、开发与遴选。