磷酸钙盐法回收剩余污泥超声波处理上清液中磷的研究

在污泥减量化处理中,细胞微生物中的碳氮磷等会释放到上清液中。为了对上清液中的磷进行有效回收,在前期研究的基础上,以生物厌氧好氧除磷(An/O)工艺的剩余污泥超声波处理上清液为研究对象,考察了磷酸钙盐(HAP)法的磷回收效果。结果表明:HAP法反应较快,5 min时反应基本完成;初始pH值在8.5～10.0时,回收率均可保持在较高水平;最佳钙磷比(Ca2+/PO34--P)为3.87。在以上最佳工艺条件下,总磷(TP)、正磷酸盐(PO34--P)的回收率分别达到88.4%、94.0%,同时对上清液中的有机物、氮也有一定的去除。     

Influence of maternal food availability on offspring dispersal

Prenatal effects caused by the maternal environment during gestation are known to contribute to the phenotype of the offspring. Whether they have some adaptive value is currently under debate. We experimentally tested the existence of such a maternal effect (food availability during gestation) on dispersal of offspring in the common lizard (Lacerta vivipara). Pregnant females were captured and kept in the laboratory until parturition. During this period, females were offered two rates of food delivery. After parturition, we released mothers and offspring at the mother's capture point. Dispersal of young was significantly affected by the mother's nutrition. To our knowledge, this is the first evidence of a prenatal effect on dispersal. Offspring of well fed mothers dispersed at a higher rate than those of less well fed mothers. As current hypotheses clearly predict the opposite result, our evidence calls for their reassessment. Dispersers are not always the least fit individuals or those coming from the poorest environments.     

Evaluation of X,Y, 18, and 13/21 alpha satellite DNA probes for interphase cytogenetic analysis of uncultured amniocytes by fluorescence in situ hybridization

The major aneuploidies diagnosed prenatally involve the autosomes 13, 18, and 21, and sex chromosomes. Fluorescence in situ hybridization (FISH) allows rapid analysis of chromosome copy number in interphase cells. This prospective study evaluated the use of four commercially available centromeric DNA probes (DXZ1, DYZ1, D18Z1, and D13Z1/D21Z1) for direct analysis of uncultured amniocytes. One hundred and sixteen amniotic fluid samples were analysed by FISH and standard cytogenetics. This evaluation demonstrated that FISH with, X, Y, and 18 alpha satellite DNA probes could accurately and rapidly detect aneuploidies involving these chromosomes and could be used in any prenatal clinical laboratory. In contrast, the 13/21 alpha satellite DNA probe hybridizing both chromosomes 13 and 21 was unreliable for prenatal diagnosis in uncultured amniocytes.     

Women's opinions on the offer and use of maternal serum screening

We studied the opinions and experiences concerning maternal serum screening of two groups of women: (A) women who were not eligible for prenatal diagnosis; and (B) women for whom prenatal diagnosis was available because of advanced maternal age, and who either underwent chorionic villus sampling or amniocentesis. Many of the women were in favour of the availability of serum screening and would apply for this test in a future pregnancy. This applied also to many respondents who had previously undergone prenatal diagnosis. Most of these women, however, did not intend to decline diagnostic amniocentesis if the screening results did not indicate an increased risk. The majority of the group of respondents of 36 years and over did not consider it acceptable if age indication was dropped altogether. A system based on serum screening will have other implications than a policy based on age indication, since specific individual risk assessment is perceived as being of more significance than a risk statistically derived from age alone. Serum screening is often seen as a means of reassurance and many women are not aware of the possible drawbacks. As technology becomes increasingly complicated, counselling has to be adjusted correspondingly. Further research is needed to establish whether and how distress can be minimized and well-considered individual choice can be achieved.     

First trimester chorionic villus sampling versus mid-trimester genetic amniocentesis-preliminary results of a controlled prospective trial

This controlled prospective study assesses the relative risks of first trimester chorionic villus sampling (CVS) versus mid-trimester gentic amniocentesis (GA). CVS subjects and amnio-centesis controls were comparable with regard to several confounding variables which might influence the risk of pregnancy loss including maternal age, smoking, alcohol consumption, gestational age at study entry, and history of vaginal bleeding or poor prior reproductive outcome. The most common indication for prenatal diagnosis was advanced maternal age (n = 511). In this subgroup, spontaneous abortion (<24 weeks) occurred in 2·9 per cent of CVS subjects versus 4−3 per cent of amniocentesis controls. The sum of spontaneous and therapeutic abortions (<24 weeks) was identical (5·3 per cent) in both groups. Therefore, intervention in the CVS group (i.e., therapeutic abortion for cytogenetic abnormalities) did not influence the observed risk of pregnancy loss. Overall perinatal mortality rates were also similar in both groups. No significant differences were identified for a number of pregnancy outcome parameters including 5 min Apgar score, birth weight, body length, head circumference, gestational age at delivery, preterm delivery, fetal growth retardation, congenital malformations, and neonatal complications. Preliminary results of this controlled prospective study suggest that chorionic villus sampling carries a low and acceptable risk.     

First trimester prenatal diagnosis of haemophilia A: Two years' experience

We evaluated the feasibility, reliability, and acceptability of prenatal diagnosis of haemophilia A by DNA analysis of chorionic villi. Twenty-two women at risk to transmit the abnormal gene were referred for prenatal diagnosis, two of them twice. Two of the 22 women appeared to be non-carriers by DNA analysis. In one of these women, the results were known only after chorionic villus sampling had been carried out. Thirteen of the twenty carriers were heterozygous for an intragenic (Bell or Xbal) marker; six women were only heterozygous for the extragenic DXS52 (Stl4) locus. One of the women was homozygous for all the presently known DNA markers within or closely linked with the factor VIII locus. Twelve of the 22 fetuses at risk were male, ten were female. Seven of the 12 male fetuses were shown to be affected and were subsequently aborted. Four male fetuses appeared to be not affected. In one case, the diagnosis was made by use of an extragenic marker. The woman rejected fetal blood sampling to confirm the diagnosis. After birth, a normal factor VIII level was found in three of the four cases. The fourth pregnancy is still continuing. In one of the 12 male fetuses, no diagnosis at the gene level was possible. DNA analysis is expected to provide maximum certainty as to the phenotype of the fetus for approximately 60 per cent of the women; for another 37 per cent a rate of misdiagnosis of 4–5 per cent applies. In only 3 per cent of the cases will no diagnosis at the gene level be possible as yet. The new possibility of a prenatal diagnosis in the first trimester of pregnancy enabled some of these women to have a family of their own and was appreciated in particular by the women who underwent fetoscopy in an earlier pregnancy.     

Early prenatal diagnosis of congenital hypophosphatasia: Case report

Congenital hypophosphatasia is an autosomal recessive disorder, which usually has a fatal outcome during the neonatal period. This report presents the prenatal diagnosis of hypophosphatasia at 16 weeks of gestation. The characteristic ultrasonic findings in this abnormality demonstrate the superiority of ultrasound as compared with radiography.     

超声去除垃圾渗滤液中的氨氮

采用超声辐照技术去除垃圾渗滤液中的氨氮.研究结果表明,超声辐照对垃圾渗滤液中的氨氮有很好的去除效果.渗滤液中氨氮超声去除的机理主要是氨氮以游离氨的形式在空化泡内发生高温热解反应,生成氮气和氢气而排出.     

超声-过氧化氢-氧化铜组合技术催化氧化水中苯酚

研究了超声-H2O2-CuO组合技术对苯酚的降解效果。考察了苯酚初始浓度、溶液温度及鼓入空气对苯酚去除率的影响。实验结果表明，与未鼓入空气时相比，连续鼓气时苯酚的降解效果较好；初始浓度低，苯酚去除率高；溶液温度从20％上升到55％时，苯酚去除率随温度升高而增大，温度对该过程的影响主要表现为对催化剂的影响而不是对超声作用的影响。高效液相色谱分析表明，苯酚降解的中间产物主要为对苯二酚、邻苯二酚及其他有机小分子物质，最终产物为草酸、二氧化碳和水。     

Enzyme extraction by ultrasound from sludge flocs

Enzymes play essential roles in the biological processes of sludge treatment. In this article, the ultrasound method to extract enzymes from sludge flocs was presented. Results showed that using ultrasound method at 20 kHz could extract more types of enzymes than that ultrasound at 40 kHz and ethylenediamine tetraacetic acid (EDTA) methods. The optimum parameters of ultrasound extraction at 20 kHz were duration of 10 min and power of 480 W. Under the condition, ultrasound could break the cells and extract both the extracellular and intercellular enzymes. Ultrasound power was apparently more susceptive to enzyme extraction than duration, suggesting that the control of power during ultrasound extraction was more important than that of duration. The Pearson correlation analysis between enzyme activities and cation contents revealed that the different types of enzymes had distinct cation binding characteristics.