Maternal cell contamination in cultured chorionic villi: Comparison of chromosome Q-polymorphisms derived from villi,fetal skin,and maternal lymphocytes

Maternal cell contamination of chorionic villi (CV) samples used for first trimester prenatal diagnosis can cause obvious and/or unrecognized diagnostic dilemmas. The purpose of this investigation is to assess the frequency of maternal cell contamination (MCC) in chorionic villus samples and to evaluate selected parameters which might predict where contamination is more likely to have occurred. Maternal lymphocytes, chorionic villi from ultrasonically directed transcervical catheter aspiration, and fetal tissue were obtained at 8–11 weeks gestation from 45 patients undergoing elective termination. Quinacrine (Q) banded metaphases were compared from duplicate direct preparations of chorionic villi; cultured chorionic villi, fetal fibroblast tissue cultures, and maternal lymphocyte cultures. Q-polymorphisms in metaphase chromosomes were 100 per cent concordant between fetal tissue and direct CV preparation. However, evidence for maternal cell contamination occurred in 13.1 per cent of cultured chorionic villi preparations where polymorphisms were found to be identical between maternal and cultured CV and both distinct from fetal tissue preparations. Where MCC was identified, it was noted that CV cell cultivation interval was prolonged (24.2±6.8 days) compared with non-contaminated cultures (14.1±4.4 days) (p <0.05). We conclude that maternal cell contamination is a significant problem with chorionic villus sampling. Where direct preparations are not employed or when cultures are ‘slow growing’, MCC may be a significant and unrecognized complication re: fetal diagnosis. Direct preparations, multiple cultures, quinacrine banding, and maternal Q-polymorphism comparisons can minimize diagnostic dilemmas secondary to maternal cell contamination. Q-polymorphism comparisons between maternal and fetal chromosomes should be included in all instances where cultured chorionic villi are utilized for fetal diagnosis and where direct preparations are not available.     

离子色谱法替代铬酸钡光度法测定硫酸根可行性探讨

探讨了以清洁水质和标准样品为实验对象，分别采用离子色谱法和铬酸钡光度法进行对比实验，根据实验结果证明了用离子色谱法替代铬酸钡光度法测定硫酸根离子可行性。     

臭氧发生系统中半导体制冷干燥装置的研制

本文介绍了未经过干燥处理的原料气进入电晕放电臭氧发生系统后的危害机理 ,根据半导体的制冷干燥机理 ,开发研制了实验室用半导体制冷干燥装置 ,实验证明该装置的研制是成功的。     

The direct photolysis and photocatalytic degradation of alachlor at different TiO2 and UV sources

Direct photolysis and photocatalytic degradations of alachlor, a widely used herbicide, were studied using three different monochromatic UV lamps (254, 300 and 350 nm) and two TiO(2) sources. Both the direct photolysis and photocatalytic degradations of alachlor follow pseudo-first-order decay kinetics. TiO(2)-P25 was found to be an effective photocatalyst compared to TiO(2)-BDH. The direct photolysis of alachlor was dominant at 254 nm even if TiO(2) was present in the solution. Among the three UV wavelengths used, the highest photocatalysis quantum yield was obtained at 300 nm. The photocatalytic degradation rate of alachlor increased with the dosages of TiO(2), but an overdose of TiO(2) would retard the reaction due to light attenuation. Photocatalytic reactions were slightly enhanced in an alkaline medium, and the different proton sources causing various degrees of rate retardation were due to the presence of the corresponding counter anions. This effect was diminished at a later stage after the reaction intermediates were formed.     

A feasibility study on the predictive emission monitoring system applied to the Hsinta power plant of Taiwan Power Company

The continuous emission monitoring system (CEMS) can monitor flue gas emissions continuously and instantaneously. However, it has the disadvantages of enormous cost, easily producing errors in sampling periods of bad weather, lagging response in variable ambient environments, and missing data in daily zero and span tests and maintenance. The concept of a predictive emission monitoring system (PEMS) is to use the operating parameters of combustion equipment through thermodynamic or statistical methods to construct a mathematic model that can predict emissions by a computer program. The goal of this study is to set up a PEMS in a gas-fired combined cycle power generation unit at the Hsinta station of Taiwan Power Co. The emissions to be monitored include nitrogen oxides (NOx) and oxygen (O2) in flue gas. The major variables of the predictive model were determined based on the combustion theory. The data of these variables then were analyzed to establish a regression model. From the regression results, the influences of these variables are discussed and the predicted values are compared with the CEMS data for accuracy. In addition, according to the cost information, the capital and operation and maintenance costs for a PEMS can be much lower than those for a CEMS.     

Fine (PM2.5), coarse (PM2.5-10), and metallic elements of suspended particulates for incense burning at Tzu Yun Yen temple in central Taiwan

Ambient suspended particulate concentrations were measured at Tzu Yun Yen temple (120 degrees, 34('), 10(") E; 24 degrees, 16('), 12(") N) in this study. This is representative of incense burning and semi-open sampling sites. The Universal-sampler collected fine and coarse particle material was used to measure suspended particulate concentrations, and sampling periods were from 16/08/2001 to 2/1/2002 at Tzu Yun Yen temple. In addition, metallic element concentrations, compositions of PM(2.5) and PM(2.5-10) for incense burning at Tzu Yun Yen temple were also analyzed in this study. The PM(2.5)/PM(10) ratios ranged between 31% and 87% and averaged 70+/-11% during incense the burning period, respectively. The median metallic element concentration order for these elements is Fe>Zn>Cr>Cd>Pb>Mn>Ni>Cu in fine particles (PM(2.5)) at the Tzu Yun Yen temple sampling site. The median metallic element concentration order for these elements is Fe>Zn>Cr>Pb>Cd>Ni>Mn>Cu in coarse particle (PM(2.5-10)) at the Tzu Yun Yen temple sampling site. Fine particulates (PM(2.5)) are the main portion of PM(10) at Tzu Yun Yen temple in this study. From the point of view of PM(10), these data reflect that the elements Fe, Zn, and Cr were the major elements distributed at Tzu Yun Yen temple in this study.     

The study of lag phase and rate improvement of TCE decay in UV/surfactant systems

The photodegradation of trichloroethene (TCE) in surfactant micelles was investigated. The decay of TCE was studied in the Rayonet RPR-200 merry-go-round photoreactor, at 253.7 nm monochromatic ultraviolet (UV) lamps, in the presence of surfactants. Surfactants are used as additional hydrogen sources to improve the photodegradation rates of TCE. About three times the rate increment is observed in the presence of Brij 35 surfactant micelles than in water alone. The increasing concentrations of H+ and Cl- indicate that they are the final products of TCE photodegradation (i.e. photodechlorination is the dominant mechanism in this system). A lag phase is observed at the beginning of the degradation, but the duration of the lag phase is apparently reduced as the initial pH increases. Because the overall decay of TCE is also found faster at higher pH levels, it is suggested that the free radical reaction is dominant at high pH levels, and the formation of lag phases is mainly due to the deficiency of free radicals at lower pH levels. The photodecomposition of TCE in surfactant micelles is also proven to be a clean and effective process. It generates no chlorinated by-products or intermediates during the process, and TCE is fully decomposed within a reasonable time.     

Consistency of ozone and nitrogen oxides standards at tropospherically relevant mixing ratios

The absolute accuracy and long-term precision of atmospheric measurements hinge on the quality of the instrumentation and calibration standards. To assess the consistency of the ozone (O3) and nitrogen oxides (NO(x)) standards maintained at the National Institute of Standards and Technology (NIST), these standards were compared through the gas-phase titration of O3 with nitric oxide (NO). NO and O3 were monitored using chemiluminescence and UV absorption, respectively. Nitrogen dioxide (NO2) was monitored directly by laser-induced fluorescence and indirectly by catalytic conversion to NO, followed by chemiluminescence. The observed equivalent loss of both NO and O3 and the formation of NO2 in these experiments was within 1% on average over the range of 40-200 nmol mol(-1) of NO in excess O3, indicating that these instruments, when calibrated with the NIST O3 and NO standards and the NO2 permeation calibration system, are consistent to within 1% at tropospherically relevant mixing ratios of O3. Experiments conducted at higher initial NO mixing ratios or in excess NO are not in as good agreement. The largest discrepancies are associated with the chemiluminescence measurements. These results indicate the presence of systematic biases under these specific conditions. Prospects for improving these experiments are discussed.     

Influence of landfill factors on plants and soil fauna-an ecological perspective

An ecological study was conducted on two landfill sites in Hong Kong. Both sites were contaminated by landfill gas and leachate, as indicated by the high concentrations of CH(4) and CO(2) and the presence of high concentration of NH(4)-N in the cover soil layer. Their plant diversity and performance, as well as the soil and litter animals, were compared with three derelict sites as references. The landfill sites had higher plant coverage and plant diversity, and higher densities of soil and litter animals than the reference sites. Similarly, the microbial activities at the landfill sites were higher than those at reference sites. The results showed that the landfill sites possessed an effective food web, starting from microbes to macroinvertebrates. Woodland establishment seems feasible at these landfill sites, and natural succession appears to take place at a higher rate at these landfill sites when compared with the reference sites.     

Enantiomeric signatures of chiral polychlorinated biphenyl atropisomers in livers of harbour porpoises (Phocoena phocoena) from the southern North Sea

The enantiomeric composition of polychlorinated biphenyl (PCB) atropisomers, including PCB 95, PCB 149 and PCB 132, was measured in 11 livers of harbour porpoises (Phocoena phocoena) from the southern North Sea. Non-racemic enantiomeric ratios (ERs) were found in some samples. The value of ERs in three of the four juvenile porpoises was equal or almost equal to one, while the ERs in all adults differed from racemic and ranged from 1.31 to 2.54 for PCB 95; from 1.19 to 1.81 for PCB 149 and from 0.45 to 0.94 for PCB 132. There were no relationships between the total concentration of PCBs and ERs. To understand the phenomena, the relationships between the ER value of individual chiral congener with age, concentration of total PCBs and PCB congener pattern were discussed. A model of intake and elimination kinetics was set up and it was tested using the ratio between concentration of PCB 153 and PCB 101 in the liver samples. There was a clear trend between the enantiomeric ratios and the ratio between PCB 153 and PCB 101. Considering that PCB 153 is one of the most persistent PCB congeners in marine mammals and PCB 101 is a relatively easy metabolised congener, this trend means that the enantiomeric ratio most likely reflects the proportion of the metabolised congener. The exposure period in contaminated conditions has a strong impact on ERs, and it is suggested that ERs in wildlife, combined with information on their anthropometric data, health status, diet and habitat conditions, might be good indicators of pollution in coastal ecosystems.