基于CDs@MIL-101-NH2复合材料的水体铅离子荧光检测方法及效果分析

为探究CDs@MIL-101-NH₂对铅离子的荧光法检测性能及荧光淬灭机理,采用水热法制备了碳点(N, S, I-CDs)修饰MIL-101-NH₂(Fe)的复合材料,使用TEM、XRD、FT-IR、XPS对复合材料进行了表征。结果表明：采用水热法成功构建了CDs@MIL-101-NH₂复合材料,碳点的引入未对MIL-101-NH₂结构造成很大影响,且氨基修饰于MOF框架上;CDs@MIL-101-NH₂复合材料在激发波长为340 nm、发射波长为436 nm、材料的质量浓度为10 mg·L⁻¹、pH为7的条件下具有最佳荧光强度;CDs@MIL-101-NH₂荧光探针可对水体铅离子做出荧光响应,有较好的选择性,在1.22~500 µmol·L⁻¹内具有良好的拟合度(R²=0.998 8),检出限为1.22 µmol·L⁻¹;荧光探针与铅离子结合后发生荧光淬灭现象,可能是由于复合材料上的氨基与铅离子发生相互作用引起的,且荧光碳点修饰提高了MIL-101-NH₂检测水体铅离子的性能;在实际水样的铅离子检测中,样品回收率为97.24%~106.16%,相对标准偏差RSD<4%,说明这一新型的CDs@MIL-101-NH₂复合材料可用于荧光法检测水体中的铅离子。本研究结果可为灵敏高效的荧光探针的设计与制备提供一种新思路,亦可为便捷的原位检测铅离子荧光方法的进一步开发和应用提供参考。     

Prenatal identification of a Y-chromosome deletion by Y-specific single copy DNA probes

A sex chromosome deletion was identified in the course of prenatal diagnosis for maternal age. Ultrasound pictures revealed male fetal sex and a comparison with the father's Y chromosome suggested that the altered chromosome might be a de novo deletion of the Y chromosome. DNA hybridization with five human Y-specific probes shows that, among the Y-specific sequences recognized by the probes, only two of them are absent. The normal infant, at birth, was mosaic 46, XYq- /46,XY.     

Fetal echocardiography using transvaginal and transabdominal probes during the first period of pregnancy: A comparative study

The authors compare the diagnostic possibilities of fetal transabdominal echocardiography versus transvaginal echocardiography. A larger diagnostic capacity is verified in different gestation ages with transvaginal probe between the 11th and 14th week of gestation. The results are emphasized by colour Doppler.     

Determination of paraquat in water samples using a sensitive fluorescent probe titration method

Paraquat (PQ), a nonselective herbicide, is non-fluorescent in aqueous solutions. Thus, its determination through direct fluorescent methods is not feasible. The supramolecular inclusion interaction of PQ with cucurbit[7]uril was studied by a fluorescent probe titration method. Significant quenching of the fluorescence intensity of the cucurbit[7]uril-coptisine fluorescent probe was observed with the addition of PQ. A new fluorescent probe titration method with high selectivity and sensitivity at the ng/mL level was developed to determine PQ in aqueous solutions with good precision and accuracy based on the significant quenching of the supramolecular complex fluorescence intensity. The proposed method was successfully used in the determination of PQ in lake water, tap water, well water, and ditch water in an agricultural area, with recoveries of 96.73% to 105.77%. The fluorescence quenching values (ΔF) showed a good linear relationship with PQ concentrations from 1.0×10^-8 to 1.2× 10^-5 mol/L with a detection limit of 3.35×10^-9 mol/L. In addition, the interaction models of the supramolecular complexes formed between the host and the guest were established using theoretical calculations. The interaction mechanism between the cucurbit[7]uril and PQ was confirmed by ¹H NMR spectroscopy.     

ESR技术应用于逆胶束酶体系性能的研究

采用鼠李糖脂构建逆胶束体系,并利用电子自旋共振（ESR）技术研究了鼠李糖脂逆胶束及鼠李糖脂逆胶束酶体系的性能.采用ESR光谱技术计算得出逆胶束体系中超精细分裂常数变化,研究表明鼠李糖脂在正己烷中的临界胶度为0.07mmol/L.通过分析ESR光谱中旋转相关时间的变化,探究电子自旋探针在逆胶束中运动受阻和翻转所需时间的情况同时,ESR光谱的峰值体现了样品中自由基含量的多少.通过对比逆胶束体系、逆胶束酶体系以及逆胶束酶-苯酚体系的ESR光谱,结果表明鼠李糖脂逆胶束-苯酚体系的自由基最多.通过研究对16-氮氧自由基硬脂酸对两个体系作用,推测出电子自旋探针自由基团定位于逆胶束水核中,并且推断电子自旋探针位于水核的边缘区域,即结合水水层.该研究为逆胶束酶体系的应用提供了坚实的理论基础.     

Measurement of total OH reactivity by laser-induced pump and probe technique—comprehensive observations in the urban atmosphere of Tokyo

Total OH reactivity was observed by use of the laser-induced pump and probe technique, and the urban air quality in Tokyo was diagnosed comprehensively. The concentrations of NO_x, CO, O₃, non-methane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (OVOCs) were observed simultaneously. The observations were conducted in July and August 2003, and in January, February, May, and November 2004. Generally, the observed OH reactivity was higher than the calculated values derived using the observed concentrations of the trace species. The differences between the observed and calculated values in summer, spring, and autumn were approximately 30%. However, the difference in winter was smaller than those in the other seasons. In addition, while the differences observed in summer, spring, and autumn correlated with the total reactivity of the OVOCs (Σ_i k_OVOCi[OVOC_i](s⁻¹), k_i is rate constant of its compounds with OH), the correlations were not confirmed in the case of winter because atmospheric oxidation was less active and OVOCs levels were low in winter. These results suggest that the secondary products of the photochemical reactions in the atmosphere would be a missing sink for the OH loss process in the urban area.     

利用电子探针对水泥净浆中Cr、As、Pb分布特征的研究

通过在模拟水泥窑中高温煅烧含Cr、As、Pb的水泥生料,制取水泥熟料,进而制备水泥净浆片.然后利用电子探针的点、线、面分析,研究了水泥净浆中Cr、As、Pb的整体分布特征及在不同矿物相中的具体分布特征,以揭示Cr、As、Pb在其中的微观物理化学形态,为建立Cr、As、Pb的释放机制提供理论基础.结果表明,Cr在水化硅酸...     

荧光定量PCR技术在环境监测中的应用研究

实时荧光定量PCR是在PCR基础上发展起来的一种核酸定量技术,此技术灵敏度高,特异性强。目前也已被国内外应用在环境监测方面。如可以用此方法来监测环境中微生物在河流中随季节的变化情况,评价菌的富集情况,快速检测微生物等。随着此技术的不断发展,此方法在环境监测方面将会有广阔的应用前景。     

应用荧光原位杂交方法检测中国沿海塔玛/链状亚历山大藻复合种(亚洲温带基因型)

近年来,有害赤潮于中国沿海频繁发生,对沿海居民身体健康、水产养殖和自然生态形成了潜在的威胁.由于部分有毒赤潮藻在很低的密度下就有可能导致严重的危害,但传统的采样和分析方法无法对这类有毒赤潮进行有效的检测,因而急需发展准确、高效的检测新方法.根据对中国沿海分离的塔玛/链状亚历山大藻(亚洲温带基因型)核糖体大亚基DNA(LSU rDNA)序列信息的分析,设计了两条特异性的荧光标记探针,并建立了针对中国沿海塔玛/链状亚历山大藻复合种(亚洲温带基因型)的荧光原位杂交检测方法室内模拟实验显示两条探针都能够特异性地标记中国沿海塔玛/链状亚历山大藻(亚洲温带基因型),但标记效果有一定差异,探针SPEC-PROBE2标记效果远好于探针SPEC-PROBE1.经过标记的藻细胞可以通过荧光显微镜和流式细胞仪区分.中国沿海塔玛/链状亚历山大藻荧光原位杂交检测方法的建立将有助于提高海水样品中亚历山大藻监测的准确性和工作效率.     

Photocatalytic degradation of Acid Blue 62 over CuO-SnO2 nanocomposite photocatalyst under simulated sunlight

The novel CuO-SnO2 nanocomposite oxide photocatalysts were prepared by simple co-precipitation method, and characterized by X- ray diffraction, transmission electron microscopy, N2 adsorption-desorption measurement and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of CuO-SnO2, evaluated using the photodegradation of Acid Blue 62 as a probe reaction under the irradiation of Xenon light, were also found to be related to the calcination temperature and the molar ratio of Cu to Sn. The maximum photocatalytic activity of the CuO-SnO2 photocatalyst was observed to be calcined at 500~C for 3 h （the molar ratio of Cu to Sn was 1：1） due to the sample with good crystallization and high surface area. It also showed much higher photocatalytic activity in treatment dye wastewater under simulated sunlight irradiation compared to Degussa P25 TiO2.