AFP transport across the fetal membranes in the human

In this investigation the original observation of a correlation between the concentration of amniotic fluid albumin and maternal serum alpha fetoprotein (AFP), as a proof for amniotic fluid-derived AFP in the maternal compartment is confirmed at 15 and 16 weeks of gestation. In contrast to the earlier reported highly significant relation in this study the correlation is only weak, especially at 15 weeks. This might be in agreement with a more frequent absence of raised maternal serum AFP levels in cases of raised amniotic fluid AFP levels prior to 16 weeks of gestation. Transamniotic AFP transport contributes a minor part of the AFP present in the maternal compartment, as also indicated by the lack of correlation between AFP concentrations in amniotic fluid and maternal serum.     

中水回用中平板膜的污染机理分析

采用间歇式生物反应器，对模拟小区生活污水的人工配水进行了生物处理；然后，在操作压力为0．1MPa，搅拌速度为300r／min条件下，选用膜生物反应器中常用的聚醚砜（PES，切割分子量分别为2万、1万和5千）、聚丙烯腈（PAN，切割分子量为20万）、聚偏氟乙烯（PVDF，切割分子量为20万）超滤平板膜和聚醚砜（PES，孔径为0．1μm）、聚丙烯腈（PAN，孔径为0．1μm）、聚偏氟乙烯（PVDF，孔径为0．1μm）微滤平板膜在实验室用死端超滤器上分别对活性污泥悬浮液进行了过滤并探讨了和间歇式生物反应器组合在一起用于中水回用的效果，结果表明：每种组合处理后的出水水质为COD〈50mg／L，NH3-N〈10mg／L，SS为0mg／L，浊度为0NTU，都达到了中水回用的水质标准（CJ25．1．89），其中生物反应器分别与PES超滤膜（5千、1万、2万）和PAN（20万、0．1μm）膜组合时，对COD的去除率较高，但所有组合对NH3-N、TOC去除率及膜的渗透通量都相差不大。此外，根据恒压堵塞过滤定律对膜的污染机理进行的研究证实：对于微滤膜和PAN（20万）超滤膜而言，由滤饼过滤过渡到完全（标准）堵塞，再到滤饼过滤；但对于PVDF（20万）和PES（2万）超滤膜，则由标准堵塞过渡到完全堵塞，再到滤饼过滤；PES（5千、1万）超滤膜的污染机理相对简单，整个过程以滤饼过滤为主。     

Effect of synthesis parameters on single gas permeation through T-type zeolite membranes

In this research, nanoporous zeolite T membranes were synthesized at three levels of synthesis temperature: 100, 120 and 140 °C and synthesis time: 15, 30 and 50 h and characterized by gas permeation. Effects of synthesis parameters on CO₂ and CH₄ permeances and CO₂/CH₄ ideal separation factors were studied. All experiments were conducted at 1 bar feed pressure and 30 °C module temperature. Normally, it is anticipated that increasing synthesis temperature and synthesis time increase gas permeances and consequently decrease ideal separation factor. This prediction was not observed in the case of synthesis temperature increase from 100 to 120 °C as well as synthesis time increase from 15 to 30 h, due to the dual effect of increasing synthesis temperature and synthesis time on gas permeances and ideal separation factor. More zeolites are deposited and larger crystals are formed at higher synthesis temperatures and times. Forming the larger crystals accelerates the rate of zeolite layer integration, which is responsible for gas separation, in one hand and reduces the density of deposited zeolite layer on the support, due to the formation of more voids, on the other hand. In terms of maximizing the CO₂/CH₄ ideal separation factor, medium synthesis temperature and synthesis time (120 °C and 30 h) can be selected, however, maximum gas permeances are obtained at low levels of synthesis temperature and time (100 °C and 15 h). According to the ranges of gas permeances (10⁻¹¹ to 10⁻⁶ mol/m² s Pa) and CO₂/CH₄ ideal separation factors (1.4–70.3), it is concluded that the zeolite T membranes synthesized at optimum conditions can be employed for membrane separation of CO₂/CH₄ mixtures.     

卷式超滤膜在蓝藻收集中的应用

利用微孔滤布-卷式超滤膜组合工艺,构建蓝藻收集中试系统,用于处理高藻期富营养化水体。考察了高藻期该工艺的蓝藻收集效率、膜通量变化及膜污染状况。结果表明,该组合工艺在进水泵频率40 Hz,进水压力0.2 MPa的条件下,定期排蓝藻浓缩液实验和蓝藻连续浓缩实验的蓝藻截留率均能达到95%以上;6 d后定期排蓝藻浓缩液实验最低...     

Uptake of aluminum by lipid vesicles

Aluminium uptake and tight binding were studied in multilayered phospholipid liposomes, as a model for cellular uptake of aluminum ions. Most of these studies were conducted with an initial aluminum concentration of 10 μM, while aluminum superficially bound to liposomes was removed by citrate chelation. Maximum uptake and tight binding of aluminium were pH‐dependent. In dimyristoyl phosphatidylcholine (DMPC) liposomes, this maximum occurred in the neutral pH region, while it was shifted towards more acidic pH values in DMPC liposomes containing 20% of acidic phosphatidylserine. The initial rate of aluminum uptake was apparently dependent on the physical state of the liposome membrane. Prior formation of an aluminum‐citrate chelate prevented aluminum uptake and tight binding to DMPC liposomes.     

原油对纳米SiO2/聚偏氟乙烯离子膜的污染及清洗技术研究

聚偏氟乙烯(PVDF)膜的疏水性限制了其在水处理领域的应用.采用纳米SiO2/PVDF离子膜电渗析对含原油高矿化度污水进行膜污染试验.结果表明,纳米SiO2/PVDF离子膜抗油珠污染的能力较强于PVDF膜.乳化油珠在电场的作用下向阴离子膜表面迁移,并在阴离子膜表面浓集、聚并,形成油膜,堵塞离子通道,少量原油以憎水膜的形式覆盖于活性基团上.扫描电镜和能谱分析表明,膜面有机污染物主要是石油类污染物,无机污染物主要是CaCO3等无机物污垢.原油污染的纳米Si02/PVDF离子膜的较佳清洗方法为碱-表面活性剂法.     

DETERMINATION OF DDT AND ITS METABOLITES IN CATTLE DIP SOIL AVAILABLE IN AQUEOUS PHASE AFTER REMEDIATION

Soil taken from a former cattle tick dip site in NSW Australia, was remediated with a chemical leaching technology. The pre- and post-remediated soil (20g) was dispersed in water (100mL) and subjected to passive diffusion using polymeric membranes. The remediation reduced tDDT from 1174.3μg/g to 102.9μg/g (ash weight basis), which was further reduced to 43.2μg/g with composting. The membranes accumulated 41.3μg tDDT/g from the dip soil, 49.2μg tDDT/g from the chemically leached soil and 3.1μg tDDT/g from the leached composted soil. The chemical leaching removed over 90% of the tDDT, but released soil bound DDT, which was converted to DDE, while 2.99μg/g was accumulated by the membranes from dip soil, 37.52μg/g was accumulated from remediated soil. Composting, however, almost eliminated the availability for passive diffusion by the membranes from 50 – 60μg/g in remediated soil to 3–3.5μg/g in composted soil. Variability studies of the membranes using eight replicates demonstrated that the accumulation by the membranes was reproducible with an average relative error of 20.3% for p,p'-DDT in soil type two, whilst the lowest average relative error for p,p'-DDE was 4.3%, suggesting that triplicate analyses will achieve acceptable accuracy.     

Enhanced sorption of perfluorooctane sulfonate (PFOS) on carbon nanotube-filled electrospun nanofibrous membranes

Multi-walled carbon nanotube-filled electrospun nanofibrous membranes (MWCNT-ENFMs) were prepared by electrospinning. The addition of MWCNTs (0.5 wt.% vs. ENFMs) doubled the specific surface area and tensile strength of the ENFMs. The MWCNT-ENFMs were used to adsorb perfluorooctane sulfonate (PFOS) in aqueous solutions. The sorption kinetics results showed that the sorption rate of PFOS onto the MWCNT-ENFMs was much higher than the sorption rate of PFOS onto the pure ENFMs control, and the pseudo-second-order model (PSOM) described the sorption kinetics well. The sorption isotherms indicated that the sorption capacity of the MWCNT-ENFMs for PFOS (16.29 ± 0.26 μmol g⁻¹) increased approximately 18 times, compared with the pure ENFMs (0.92 ± 0.06 μmol g⁻¹). Moreover, the solution pH significantly affected the sorption efficiency and sorption mechanism. The MWCNT-ENFMs were negatively charged from pH 2.0–10.0, but the electrostatic repulsion between the MWCNT-ENFMs and PFOS was overcome by the hydrophobic interactions between PFOS and the MWCNTs or nanofibers. The strong hydrophobic interactions between PFOS and the MWCNTs played a dominant role in the sorption process. For the pure ENFMs, the electrostatic repulsion was conquered by the hydrophobic interactions between PFOS and the nanofibers at pH > 3.1. In addition to the hydrophobic interactions, an electrostatic attraction between PFOS and the pure ENFMs was involved in the sorption process at pH < 3.1.     

Towards green membranes: preparation of cellulose acetate ultrafiltration membranes using methyl lactate as a biosolvent

Ultrafiltration membranes were prepared using cellulose acetate (CA) as a polymer, LiCl and CaCl₂ as porogens and methyl-(S)-lactate as a solvent. CA, methyl lactate and the porogens used in this work are obtained from renewable resources; they are biodegradable, non-toxic and non-volatile organic compounds. Flat sheet ultrafiltration membranes were prepared by the phase inversion technique. A molecular weight cut-off between 15 and 35 kDa (polyethylene glycol) and pure water permeability between 13 and 177 litres h^? 1m^? 2 bar^? 1 were obtained. These parameters are in the ideal range for water treatment industry. Improvement of pollutant degree and ecotoxicity of the process was evaluated by ‘green’ metrics by the P (pollutants, persistent and bioaccumulative) and E (ecotoxicity) parameters. Both of these variables were recorded as zero using our method. This study represents a step ahead towards the production of ultrafiltration polymeric membranes by a ‘greener’ process than current methods.