A comparative study of microvillar enzyme activities in the prenatal diagnosis of cystic fibrosis

The potential of four enzyme-based analytical systems has been compared in the secondtrimester prenatal diagnosis of cystic fibrosis (CF). Direct activity measurements were made of γ-glutamyltranspeptidase (GGTP), aminopeptidase M (APM) and the intestinal isoenzyme of alkaline phosphatase (ALP). In the fourth system the proportions of total ALP inhibited by phenylalanine and homoarginine, respectively, were assessed. Each system was applied to amniotic fluid samples from 94 pregnancies with al in 4 risk of CF, divided into retrospective (36) and prospective (58) series. No system gave an absolute separation of affected from unaffected cases. Measurement of APM and intestinal ALP (phenylalanine-inhibitable ALP) gave a better detection rate for CF (35 of 41 cases, 85 per cent) than did measurement of GGTP (63 per cent) or assessment of ALP proportions (76 per cent). APM had a lower false positive rate (4 per cent) than intestinal ALP (8 per cent). For both the latter systems the detection rate of CF rose to 96 per cent (25 of 26), if gestations less than 17 weeks were excluded.     

苯胺水溶液的电子束辐照降解

以苯胺类化合物中的苯胺为具体对象,进行了苯胺水溶液受到电子束辐照后的降解过程和特性研究,分别考察了吸收剂量、溶液初始浓度、溶液初始pH和过氧化氢加入量等因素对苯胺辐照降解效果的影响.实验结果表明,电子束辐照可以有效降解水溶液中的苯胺,当苯胺初始浓度为70 mg·L-1,吸收剂量为23.7 kGy时,苯胺降解率可达91%,COD去除率可达27%.过氧化氢的加入能够明显地提高苯胺的降解效果,COD去除率最高可达98%.溶液初始pH在2.0～11.0范围内,pH对苯胺的辐射降解影响较小.     

UV强化草酸络合Fe2+活化过硫酸盐氧化苯胺研究

采用UV强化草酸络合Fe2+活化过硫酸钠(PS)氧化降解苯胺,研究了UV光照促进苯胺降解的作用机制,考察了pH、草酸浓度和UV光照强度对PS活化及苯胺降解的影响.结果表明,引入UV光照后,草酸络合Fe2+活化PS体系中的PS活化率和苯胺降解率分别提高了68%和41%.在该过程中,UV可通过光解或光电离水分子产生·OH、促进发生光化学Fenton反应、直接活化PS等作用机制降解苯胺,但通过光化学反应促进Fe2+循环转化是提高PS持续活化效果和苯胺去除的首要作用机制;中碱性及强酸性环境因不利于Fe(C2O4)3-3形成,会对PS活化过程产生抑制,但当初始pH为7和9时,由于PS活化分解促进反应体系pH下降,PS活化及苯胺降解均取得较好效果;草酸浓度的增加有利于PS活化,但当草酸浓度高于2.5 mmol·L~(-1)时,会对SO·-4产生强烈竞争,导致苯胺降解率出现下降;增加UV光照强度能显著促进PS活化和苯胺氧化去除,当UV光照强度达到117μW·cm-2时,反应150 min后,PS的分解率和苯胺的去除率均可达到100%.     

TiO2表面沉积Ag粒子及其可见光下降解含盐废水中的苯酚

为了制备可见光激发下能高效降解含盐废水中有机物的光催化剂,首次以商用TiO_2光催化剂(P25)为载体,利用吸附相反应技术一步获得了Ag沉积的可见光响应复合光催化剂.同时,通过XPS、TEM、HRTEM及紫外可见漫反射光谱图,结合多种高含盐水体系中苯酚的光催化降解过程,研究了不同Ag沉积对催化剂可见光活性的影响.结果发现,吸附平衡后P25表面富含水的吸附层可作为反应和粒子的生成场所,生成量子尺寸的Ag粒子.另外,在吸附层中生成的Ag粒子均匀分布于P25表面并与之紧密结合,并在TiO_2晶格结构中引入晶格交错结构.Ag与TiO_2的表面等离子体共振效应和晶格交错结构共同提升了催化剂的可见光响应和电荷的分离效率,增强了催化剂对苯酚的可见光催化性能.在含盐废水体系中,盐离子数量越多,催化剂在可见光下降解苯酚过程受到的干扰越大.     

空间环境下碳纤维/双马树脂基复合材料的性能演化及损伤机理

目的基于碳纤维/双马树脂基(CF/BMI)复合材料在航天结构材料中广泛的应用前景,研究其性能演化及损伤机理,为评估与预测其在空间环境下的服役性能及寿命提供理论依据。方法利用地面试验装置模拟不同的空间环境因素包括真空热循环、质子辐照和电子辐照,利用动态力学分析(DMA)、热重分析(TGA)、X射线光电子能谱(XPS)、热膨胀分析、原子力显微镜(AFM)和力学性能测试等手段系统地研究CF/BMI复合材料在空间环境下的性能变化及损伤行为。结果真空热循环能够引发复合材料产生脱气行为与界面脱粘效应,使其横向拉伸强度退化,弯曲强度和层间剪切强度受到热循环初期固化交联作用的影响,呈现先升高后降低的变化趋势。质子辐照导致材料表面层化学键断裂及碳化,使力学性能及热性能受到一定程度的损伤。电子辐照能够引发辐照交联和辐照降解作用,在较高束流量辐照下降解作用占据主导地位成为复合材料力、热性能退化的决定性因素。结论预期研究成果为CF/BMI复合材料在空间环境下的服役性能及寿命的评估与预测提供了必要的理论依据。     

煅烧温度对γ-Fe_2O_3催化剂结构及其脱硝活性的影响

采用沉淀-微波热解法,以Fe SO4·7H2O为铁源制备环境友好的γ-Fe2O3催化剂,结合XRD(X射线衍射)、N2等温吸附-脱附、SEM(扫描电子显微镜)、EDS(能谱仪)等手段对催化剂样品的晶相、孔结构、表面形貌、表面元素组成等进行表征,并考察其NH3-SCR(选择性催化还原)脱硝性能,研究煅烧温度对γ-Fe2O3催化剂物性及NH3-SCR脱硝性能的影响规律.结果表明:300、350和450℃下煅烧制备的催化剂中生成的杂质α-Fe2O3对SCR反应不利,而400℃煅烧制备的γ-Fe2O3催化剂脱硝性能最优,NOx转化率最高可达95%以上,XRD结果表明其纯度高,并且在60~100 nm孔径区间具有发达的孔隙结构,有利于SCR反应进行;随着煅烧温度升高,γ-Fe2O3催化剂表面晶格氧逐渐增加,颗粒形貌经历了片状颗粒(300、350℃)→球状颗粒(400℃)→针状颗粒(450℃)的变化过程,均匀的球状颗粒形貌及其表面丰富的晶格氧是400℃煅烧制得催化剂具备最优脱硝性能的重要因素.     

Photoassisted Fenton degradation of phthalocyanine dyes from wastewater of printing industry using Fe(Ⅱ)/γ-Al2O3 catalyst in up-flow fluidized-bed

Fe(II)/γ-Al2O3 powders synthesized using the dipping method were produced from a mixed aqueous solution containing aluminium oxide(γ-Al2O3) and iron(II)-precursor(FeSO4), and used for photoFenton degradation of phthalocyanine dyes(PCS) under ultraviolet(UV) irradiation in an up-flow fluidized bed. The catalysts were characterized by XRD, ESCA, BET, EDS and SEM. The results showed that Fe2+ion was compounded on the γ-Al2O3 carrier. The effects of different reaction parameters such as catalyst activity, dosage and solution pH on the decolorization of PCS were assessed. Results indicated that maximum decolorization(more than 95%) of PCS occurred with20 wt% Fe(II)/γ-Al2O3 catalyst(dosage of 60 g/L) using a combination of UV irradiation and heterogeneous Fenton system. The degradation efficiency of PCSincreases as pH decreases, exhibiting a maximum efficiency at pH 3.5. The recycled catalyst was capable of repeating three runs without a significant decrease in treatment efficiency, and this demonstrated the stability and reusability of catalyst.     

气相中乙酸乙酯光解的光子效率:波长和催化剂的影响

采用4种不同波长的准分子光源(Xe Cl*、Kr Cl*、Xe Br*和Kr Br*)降解气相的乙酸乙酯.对比了外加3种负载型光催化剂(有机膜负载Ti O2、有机膜负载石墨烯和纱网负载Ti O2)条件下乙酸乙酯的去除率,考察了光源类型、辐射功率和气体初始浓度对去除率的影响.同时,测定了不同光源的辐射光谱和辐射功率,计算了不同反应条件下的光子效率.结果表明,乙酸乙酯去除率按Kr Br*Kr Cl*Xe Cl*Xe Br*依次降低,而Xe Cl*和Kr Br*光源降解乙酸乙酯气体可以得到较高的光子效率;有机膜负载Ti O2比不加催化剂时乙酸乙酯去除率和光子效率都有所提高,但提高幅度不大.气体流速和乙酸乙酯初始浓度升高,光子效率升高.采用Kr Br*准分子灯直接光解乙酸乙酯,实验条件为:辐射功率0.76 W,乙酸乙酯初始浓度946mg·m-3,气体流速600 m L·min-1,光子效率为5.63%.     

宝玉石改色原理与辐照改色宝石的残余放射性

传统的宝石改色是以泰国的还原热处理工艺为代表，现已逐渐被人们所接受。现代科技与珠宝工艺相结合，出现辐照改变宝石颜色，然而，部分宝石因辐照而带有残余放射性，对消费者造成伤害．本文指出了宝玉石射线来源与防护措施。