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排序方式: 共有128条查询结果,搜索用时 953 毫秒
51.
C. Rosatelli F. Schettini G. Monni T. Tuveri M. T. Scalas A. Di Tucci G. B. Leoni Professor A. Cao 《黑龙江环境通报》1988,8(5):393-397
This report describes a couple at risk for β thalassaemia in which one spouse was heterozygous for classical high Hb A2 β-thalassaemia while the other had the compound heterozygous state for β+-thalassaemia and a β-chain variant. This variant comigrates on carboxymethyl-cellulose columns (CMC) with γ-chains, indicating that globin separation on CMC columns could not have been used for fetal diagnosis. The β-chain variant migrates separately from the other globin chains on HPLC and the respective abnormal haemoglobin can be separated by isoelectrofocusing. Oligonucleotide hybridization showed that both parents were carriers of the β+ IVS-1, nt 6 mutation. Prenatal diagnosis was successfully accomplished by oligo-nucleotide analysis on trophoblast DNA. This case indicates that an Antenatal Service should have alternative methods to CMC columns so as to carry out prenatal diagnosis of β-thalassaemia in uncommon cases. 相似文献
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Smith CB Anderson JE Fischer RL Webb SR 《Environmental pollution (Barking, Essex : 1987)》2002,120(3):517-520
Green fluorescent protein (GFP) was first isolated in the early 1970s for experimental use from coelenterates or the Pacific jellyfish. Aequorea victoria (Morin and Hastings, 1971). GFP has since become a favored biomarker in the photophysical analysis of molecular and cell biology because of its strong intrinsic visible fluorescence and the feasibility of fusing it to other proteins without affecting their normal functions (Creemers et al., 2000). Here we report using Bacillus subtilis expressing GFP to evaluate the influence of different environmental pH conditions on GFP fluorescence. Emission acquisitions were configured to excite at 471 nm and detect at an emission from 490 to 650 nm at 1-nm increments. Fluorescence intensity was significantly better at pH 7 (4.2 x 105 cps; P-value < 0.01) than at acid or alkaline conditions. GFP is a good biomarker for environments near netural conditions: however, GFP may be unsuitable where soils or waters are below or above pH 7 because of loss in fluorescence intensity. Alternative fluorescent markers and delivery systems must be examined in different environments to optimize responses from bioreporter molecules. 相似文献
55.
高占祥 《城市环境与城市生态》2003,16(3):58-59
文章揭示了造成环境监测仪器的氨气敏电极损坏的原因,提出了延长其使用寿命的方法。首先要保护电板的引线,必须严格按照使用说明书定期进行认真的保养维护,实施氨气敏复合电极膜及其填充液的更换,保护好电极,可延长其寿命。 相似文献
56.
Vanesa Benito Javier Etxebarri Felipe Goñi-de-Cerio Iñigo Gonzalez Pilar Brettes Ana Urkiaga 《环境科学学报(英文版)》2020,32(4):51-58
This study aims to demonstrate the validity of fluorescence-based methods, together with flow cytometry, as a complementary tool to conventional physicochemical analyses carried out in wastewater treatment plants (WWTPs), for the control of the currently largely unknown activated sludge process. Staining with SYTO 9, propidium iodide and 5-(and 6)-carboxy-2′,7′-difluorodihydrofluorescein diacetate (carboxy-H2DFFDA) was used for cell viability and oxidative stress monitoring of the bacterial population forming the activated sludge of a WWTP. Throughout the period of research, several unstable periods were detected, where the non-viable bacteria exceeded the 75% of the total bacterial population in the activated sludge, but only in one case the cells with oxidative stress grew to 9%, exceeding the typical values of 2%–5% of this plant. These periods coincided in two cases with high values of total suspended solids (SST) and chemical oxygen demand (COD) in the effluent, and with an excess of ammonia in other case. A correlation between flow cytometric and physicochemical data was found, which enabled to clarify the possible origin of each case of instability in the biological system. This experience supports the application of bacterial fluorescence staining, together with flow cytometric analysis, as a simple, rapid and reliable tool for the control and better understanding of the bacteria dynamics in a biological wastewater treatment process. 相似文献
57.
目的从监测信号中恢复有效腐蚀信息(长期变化趋势、周期性窄带尖峰),提出一种基于经验模态分解(Empirical Mode Decomposition,EMD)和小波阈值去噪(Wavelet Threshold Denoised,WTD)相结合的自适应去噪算法(EMD-WTD)。方法先将信号进行EMD分解,利用最大信息系数(Max Information Coefficient,MIC)判断噪声主导和有效信号主导信号分量的分界点,然后将噪声主导的信号分量进行自适应小波阈值去噪。最后以人工模拟信号和电阻探针监测信号进行验证。结果 EMD-WTD算法能有效去除噪声,信噪比可提升10 d B以上。结论与多个去噪算法相比,EMD-WTD算法能够更好地保留信号中周期性窄带尖峰信息,为后续准确建立电阻探针监测信号与环境之间的数学模型奠定了基础。 相似文献
58.
固体颗粒沉积对7B04 铝合金初期大气腐蚀行为的影响 总被引:1,自引:1,他引:0
目的研究Na Cl,C,Si O2三种固体颗粒对7B04铝合金初期大气腐蚀行为的影响。方法通过对三种固体颗粒沉积试样进行户内暴露试验,结合质量增量测试、腐蚀形貌观察、微区电化学测试等手段研究7B04铝合金在不同固体颗粒沉积下的初期腐蚀行为。结果经过不同周期暴露试验后,Na Cl与Si O2颗粒沉积7B04铝合金在腐蚀初期即有点蚀萌生,且腐蚀质量增量随暴露时间呈上升趋势;C颗粒沉积7B04铝合金在暴露后期出现少量点蚀,无明显腐蚀质量增量。三种颗粒沉积后7B04铝合金表面电位呈不均匀分布,并随暴露时间的增加,电位分布发生了变化。结论在25℃,RH为95%条件下,Na Cl与Si O2颗粒沉积均可诱发7B04铝合金的大气腐蚀,而C颗粒沉积则无诱发作用。 相似文献
59.
Alessandra P. Vargas Diego Alves Caroline Wagner Thais Posser Robson Luiz Puntel 《Chemistry and Ecology》2013,29(4):355-364
Heavy metal contamination of the environment is a public health problem and research to develop new tools for monitoring the environmental impact of these elements is necessary. This study describes the preparation of a rhodamine-based probe 1 and its potential applications for detecting mercuric ion [Hg(II)] in samples from a nutrition media containing Salvinia auriculata. It was observed that an excess of probe 1 led to quenching in the fluorescence/absorption response, which was evidenced by a decrease in the signal when the stoichiometry differed from 1:1. Consequently, this probe is not suitable for quantitative analysis of Hg(II). Also, probe 1 reacts with methylmercury (MeHg) with different stoichiometry than that observed for Hg(II). These results indicate the potential application of probe 1 for qualitative detection of Hg(II) and MeHg in environmental samples. 相似文献
60.
Wen-Jun Ju Ritsu Dobashi Toshisuke Hirano 《Journal of Loss Prevention in the Process Industries》1998,11(6):423-430
Reaction zone structures and propagation mechanisms of two representative flames established in stearic acid (CH3(CH2)16CO2H) particle clouds have been investigated. The reacting zone structure was examined by using a micro-electrostatic probe and a high-speed schlieren system. A distinct difference was observed in the ion current fluctuations recorded across the two representative flames propagating through the clouds of the same total mass density of particles and different mass densities of the particles smaller than 60 μm in diameter. When the mass density of smaller particles was high, a single peak was recorded in the ion current fluctuation. On the other hand, when the mass density of smaller particles was low, multi-peaks of various heights and widths were recorded. In the former case, the single peak was considered to be attributable to a unitary and a relatively thin flame started burning in vapor generated by the evaporation of smaller particles in the preheat zone. The flame propagation mechanism in this case was inferred to be similar to that of a usual hydrocarbon–air premixed flame, although the reaction zone thickness is much larger than that of the premixed flame. In the latter case, the multi peaks of various shapes were considered to be attributable to strong combustion at blue spots far behind the schlieren front. The flame propagation in this case was inferred to be supported by the heat release due to combustion at the blue spots. 相似文献