Preparation of Magnesium-Aluminum Hydrotalcite by Mechanochemical Method and Its Application as Heat Stabilizer in poly(vinyl chloride)

The traditional methods for preparing magnesium aluminum layered double hydrotalcite (Mg₂Al-CO₃LDHs) in industry include coprecipitation and hydrothermal methods. Both these methods have the disadvantages of high preparation cost and complicated water washing process. Using Mg(OH)₂, Al(OH)₃, and CO₂ as raw materials in this work, the Mg₂Al-CO₃ LDHs are successfully prepared by mechanochemical method, which solves the shortcomings of traditional preparation method and realizes the conversion and utilization of CO₂ resource. The prepared Mg₂Al-CO₃ LDHs are evaluated as a heat stabilizer in poly(vinyl chloride) (PVC). The result indicates that, when 2.4 phr Mg₂Al-CO₃ LDHs, 0.3 phr ZnSt₂, and 0.3 phr of zinc acetylacetonate are added to the PVC, the thermal stability time of PVC can reach 190 min, which is better than PVC containing commercial Mg₂Al-CO₃ LDHs. Meanwhile, its processing performance is basically the same as the PVC containing commercial Mg₂Al-CO₃ LDHs.     

Modelling of the Guillotine Cutting Process by Means of a Symmetrical Blade with the Defined Geometry

This paper modelled the cutting process of a bundle consisted of ultra-thin cold-rolled steel sheets using a guillotine. The geometry of a cutting tool with given dimensions was assumed. A bundle of sheets being cut was modelled as deformable, the cutting tool was rigid, and the finite element method along with computer system LS-DYNA was employed. Numerical simulations of the complex state of stress and of the corresponding complex state of strain were carried out. Cutting processes belong to fast changing physical phenomena, and therefore, highly nonlinear dynamical algorithms were applied in order to solve this particular problem. Experimental investigations were also conducted by means of the scanning electron microscopy. It was found that the fracture region consisted of two distinct zones: brittle and ductile separated from each other by the interfacial transition. Morphological features of the brittle, ductile, and the transition regions were identified. The ductile and brittle zones were separated at the depth of ca. 1/5 thickness of the cut steel sheet. Finally, the numerical results obtained by usage of the finite element method as well as experimental ones in the form of microscopic images were compared, showing quite good agreement.     

The Effects of Oxygen Functional Groups on Graphene Oxide on the Efficient Adsorption of Radioactive Iodine

Oxygen-containing functional groups tend to induce a strong interaction between solid adsorbents and iodine molecules, yet have not been systematically investigated. Herein, on the basis of a series of nitric acid-treated graphene oxide (GO) with different contents of oxygen functional groups for iodine adsorption, it was found that the iodine uptake capacity is proportionate to the oxygen content and the diversities of oxygen-containing groups. The density functional theory (DFT) calculation results also suggest that oxygen-containing groups result in strong interactions between iodine molecules and the adsorbents through a covalent bond-forming process, among which -OH groups possess a higher adsorption energy averagely. Such theoretical and experimental work deepens our understanding of the effects of oxygen functional groups on iodine adsorption and provides novel ideas for future design and synthesis of high-performance solid adsorbents for radioactive iodine.     

湖南白族少年儿童体型特征

目的探讨湖南白族少年儿童体型发育特征及其规律。方法采用Heath-Carter体型法对1525例(男性748例,女性777例)湖南白族少年儿童的体型进行评价。结果男性中因子值大于女性,内因子值小于女性;男性体型以中胚层、外胚层为主,女性体型以中间型、外胚层为主;随着年龄增长,男性由均衡的中胚层体型、偏外胚层的中胚层体型、中胚层-外胚层均衡体型、偏中胚层的外胚层体型发展为中胚层-外胚层均衡体型。女性由中间型、均衡的外胚层体型、中间型、内胚层-中胚层均衡体型发展为偏中胚层的内胚层体型。结论白族少年儿童男女性的体型发育存在着差异,男性身体线性程度相对较高,肌肉发达;女性脂肪含量较多、线性度较差。与蒙古族等群体比较,白族学生脂肪含量较少,身材矮小,肌肉不发达。     

干血片法孕中期产前筛查Down＇s综合征的应用探讨

目的应用二联血清法与滤纸干血片法对孕中期Down’s综合征进行产前筛查,以了解其一致性。方法应用DELFIA法同时应用PE公司产前筛查血清二联法及滤纸干血片法分析AFP及Freeβ-HCG含量。结果血清与血片法以血清法为金标准,DS切值均为1/270时,其敏感度为93.22%,特异度为99.8%,准确度为99.5%。结论经筛查1479例中孕妇女血清法筛查高风险率3.99%（59/1479）,滤纸干血片法高风险率为3.92%（58/1479）,P〉0.05,χ^2=0.01,无统计学差异,显示产筛二联血清法与滤纸干血片法对于DS筛查高风险者结果一致性好,可推广应用于中孕期DS筛查。     

Majority Vote and Other Problems when using Computational Tools

Computational tools are essential for most of our research. To use these tools, one needs to know how they work. Problems in application of computational methods to variation analysis can appear at several stages and affect, for example, the interpretation of results. Such cases are discussed along with suggestions how to avoid them. The applications include incomplete reporting of methods, especially about the use of prediction tools; method selection on unscientific grounds and without consulting independent method performance assessments; extending application area of methods outside their intended purpose; use of the same data several times for obtaining majority vote; and filtering of datasets so that variants of interest are excluded. All these issues can be avoided by discontinuing the use software tools as black boxes.     

Quantitation of escitalopram and its metabolites by liquid chromatography‐tandem mass spectrometry in psychiatric patients: New metabolic ratio establishment

Therapeutic drug monitoring (TDM) is used to determine the concentration of drug in plasma/serum to adjust the dose of the therapeutic drug. Selective and sensitive analytical methods are used to determine drug and metabolite levels for the successful application of TDM. The aim of the study was to develop and validate using LC‐MS/MS to analyse quantitative assay of escitalopram (S‐CT) and metabolites in human plasma samples. In order to provide a convenient and safe treatment dose, it was aimed to determine the levels of S‐CT and its metabolites in the patients’ plasma. A new method with short sample preparation and analysis time was developed and validated using LC‐MS/MS to analyse quantitative assay of S‐CT and its metabolites in plasma. Also, plasma samples of 30 patients using 20 mg S‐CT between the ages of 18 and 65 years were analysed by the validated method. The mean values of S‐CT, demethyl escitalopram and didemethyl escitalopram in plasma of patients were 27.59, 85.52 and 44.30 ng/mL, respectively. At the end of the analysis, the metabolic ratio of S‐CT and metabolites was calculated. It is considered that the method for the quantitative analysis of S‐CT and its metabolites in human plasma samples may contribute to the literature on account of its sensitive and easy application. Additionally, the use of our data by physicians will contribute to the effective drug treatment for their patients who take S‐CT.     

化学发光法与胶体金法检测SARS-CoV-2抗体阳性率比较

目的　探讨化学发光法和胶体金法检测SARS-CoV-2抗体在2019冠状病毒病（coronavirus disease 2019, COVID-19）诊断中的应用价值。方法　收集51例COVID-19确诊患者和41例非COVID-19患者的血清,用化学发光法检测非COVID-19组血清中SARS-CoV-2抗体IgM、IgG及联合检测（IgM或IgG）的阳性率;用化学发光法和胶体金法检测COVID-19组血清中SARS-CoV-2抗体IgM、IgG及联合检测（IgM或IgG）的阳性率,比较2种方法的一致性。结果　COVID-19组平均发病时间为（16.9±5.4）d。其中22例IgM阳性,阳性率为43.1%;47例IgG阳性,阳性率为92.2%;49例联合检测（IgM或IgG）阳性,阳性率为96.1%。非COVID-19组中,1例IgM阳性,阳性率为2.4%;0例IgG阳性,阳性率为0;1例联合检测（IgM或IgG）阳性,阳性率为2.4%。在COVID-19组中,化学发光法与胶体金法检测SARS-CoV-2抗体联合检测（IgM或IgG）的阳性率分别为96.1%和68.6%,化学发光法优于胶体金法（P＜0.05）。结论　SARS-CoV-2抗体的检测对COVID-19诊断有重要的意义,且化学发光法检出率优于胶体金法。