探究多囊卵巢综合征患者冻融胚胎移植子宫内膜准备方案的选择

目的探讨多囊卵巢综合征患者冻融胚胎移植子宫内膜准备的两种方案的效果。方法选择2014年3月到2016年3月间在深圳武警医院选择行冻融胚胎移植子宫内膜准备的700例多囊卵巢综合征患者作为研究对象,对所有患者的临床资料进行回顾性分析,根据患者子宫内膜准备方案分为人工组(n=350)和促排卵组(n=350),对比两组患者冻融胚胎移植效果。结果人工组患者胚胎复苏率、优质胚胎率、移植胚胎数、子宫内膜厚度、胚胎种植率、妊娠率与促排卵组相比均无差异,P0.05。结论人工子宫内膜与促排卵内膜效果相似,均可推广运用。     

Detection of Frozen–Thawed Duck Fatty Liver by MALDI-TOF Mass Spectrometry: A Chemometrics Study

The marketing of poultry livers is only authorized as fresh, frozen, or deep-frozen. The higher consumer demand for these products for a short period of time may lead to the marketing of frozen–thawed poultry livers: this constitutes fraud. The aim of this study was to design a method for distinguishing frozen–thawed livers from fresh livers. For this, the spectral fingerprint of liver proteins was acquired using Matrix-Assisted Laser Dissociation Ionization-Time-Of-Flight mass spectrometry. The spectra were analyzed using the chemometrics approach. First, principal component analysis studied the expected variability of commercial conditions before and after freezing–thawing. Then, the discriminant power of spectral fingerprint of liver proteins was assessed using supervised model generation. The combined approach of mass spectrometry and chemometrics successfully described the evolution of protein profile during storage time, before and after freezing-thawing, and successfully discriminated the fresh and frozen–thawed livers. These results are promising in terms of fraud detection, providing an opportunity for implementation of a reference method for agencies to fight fraud.     

天然盐渍土冻融循环时水盐迁移规律及强度变化试验研究

通过对新疆喀什地区12处天然盐渍土室内基本性质试验分析,选取典型天然盐渍土,在开放系统中进行反复冻融循环条件下的试验研究。研究了天然盐渍土在多次冻融循环时的水分和盐分迁移规律及强度变化特征。试验结果表明:经多次冻融循环,低液限粘土试样水分重分布与盐分重分布有很大的一致性,水分和盐分自下而上迁移;试样粘聚力自下而上线形减小,内摩擦角呈s形分布。含砂低液限粘土试样冻融循环过程中,易溶盐均随水分向冷端面迁移,离子剖面呈现中间大两端小的趋势;试样粘聚力呈反s形分布,内摩擦角均呈s形分布。     

基于纳米压痕试验的混凝土微观耐久性表征

利用纳米压痕和扫描电镜研究了不同冻融循环下混凝土的微观性能,揭示了冻融循环所导致混凝土退化的机理．纳米压痕结果显示,混凝土浆体的压痕模量与硬度的相关系数很大,并且都不满足正态分布．本文利用核密度估计来计算浆体微观性能的概率密度函数．根据浆体和骨料的性能差异,用阶跃函数来拟合界面过渡区的微观力学性能,同时利用扫描电镜观察界面过渡区的形貌．采用以上两种方法研究不同冻融循环下的混凝土,发现在不同的尺度下,冻融循环对混凝土的影响不同：在纳米尺度下,由于水的参与,高密度水凝胶会进一步形成;而在微米尺度下,由于冻融循环中水结冰膨胀和材料多相性,微裂纹进一步扩展,导致断裂能量降低,混凝土表现出宏观退化．     

电场对含水物料中水分子作用的研究进展

电场解冻、电渗透脱水、高压电场干燥三方面的应用研究越来越受到人们的关注 ,是静电研究的一些新领域 ,为脱水与解冻工作开辟了一条新途径 .大量实验表明这三方面应用研究具有物料不升温、很好的保持物料有效成分和不污染环境等许多优点 .文章综述了近年来这三方面研究在国内外的进展与应用成果 ,认为它们的共性都是电场对含水物料中水分子作用的结果 ,并且对此进行了分析 .     

Study on porous silk fibroin materials: 3. Influence of repeated freeze–thawing on the structure and properties of porous silk fibroin materials

The influence of repeated freeze–thawing on pore structural characteristics and physical properties of porous silk fibroin materials prepared by freeze drying were studied. It showed that when quick‐frozen silk fibroin solution was repeatedly thawed and frozen before being vacuum dried, thus pore size of prepared porous silk fibroin materials increased from 67 µm to about 120 µm, and pore density decreased from 80 per square millimeter to about 28 per square millimeter; at the same time compression ratio and moisture permeability increased from 22.7% and 230 g/m² hr to about 33.7% and 308 g/m² hr, respectively, tensile strength and dissolvability in hot water decreased from 20.2 N/cm² and 42.7% to about 12.5 N/cm² and 26.1%, respectively. Both the times of repeated thawing and the thawing temperature had a certain influence on the above‐mentioned pore characteristic parameters and physical properties. Copyright © 2001 John Wiley & Sons, Ltd.     

Preparation and characterization of novel physically cross-linked hydrogels composed of poly(vinyl alcohol) and amine-terminated polyamidoamine dendrimer

Poly(vinyl alcohol) (PVA) and polyamidoamine (PAMAM) dendrimers are water-soluble, biocompatible and biodegradable polymers, which have been widely applied in biomedical fields. In this paper, novel physically cross-linked hydrogels composed of PVA and amine-terminated PAMAM dendrimer G6-NH(2) were prepared by cyclic freezing/thawing treatment of aqueous solutions containing PVA and G6-NH(2). The FT-IR analysis and elemental analysis indicated that PAMAM dendrimer G6-NH(2) was successfully introduced into the formed hydrogels, possibly via hydrogen bonds among hydroxyl groups, amide groups and amino groups in PVA and PAMAM dendrimer in the process of freezing-thawing cycle. Compared with physically cross-linked PVA hydrogel, PVA/G6-NH(2) hydrogels show higher swelling ratios and faster re-swelling rate due to the higher hydrophilicity of PAMAM dendrimer G6-NH(2). Higher contents of G6-NH(2) in PVA/G6-NH(2) hydrogels resulted in higher swelling ratios and faster re-swelling rates. With increasing freezing/thawing cyclic times, the swelling ratios and re-swelling rates of PVA/G6-NH(2) hydrogels decreased, which is similar to that of physically cross-linked PVA hydrogel. Combining the special host property of polyamidoamine dendrimer, these novel physically cross-linked hydrogels are expected to have potential use in drug delivery, including improving drug-loading amounts in hydrogels and prolonging drug release time. Swelling ratios of physically cross-linked PVA/G6-NH(2)-50 hydrogels prepared by three, six, nine freezing/thawing cycles. The swelling equilibrium experiments were carried out in distilled water at 25 degrees C.     

Locust Bean Gum Hydrogels Formed by Freezing and Thawing

Locust bean gum (LBG) hydrogels were prepared by freezing and thawing. It was found that the junction zone of LBG hydrogels is tightly formed by repeating freezing and thawing. During this process, LBG molecules not connected with the junction zone are excluded from the gel portion and the remaining molecules gradually form densely packed hydrogels. Molecular conformation in the sol state affects the rate of the junction formation. Obtained LBG hydrogels are thermally stable and no gel-sol transition was observed in temperatures from 40 to 100 °C by the observation of differential scanning calorimetry (DSC). Non-freezing water content calculated from the DSC melting peak of water in the gel indicates that the junction zone became dense with increasing freezing and thawing.     

An effective method for extracting anthocyanins from blueberry based on freeze-ultrasonic thawing technology

The aim of this study was to develop an effective method for extracting anthocyanins from blueberry Vaccinium spp. (ABVS) using freeze-ultrasonic thawing technology (FUTE). Various parameters including freezing time, ultrasonic time, ultrasonic temperature and liquid–solid ratio were optimized by a single-factor design and multiple response surface methodology. The amounts of extracted anthocyanin and cyanidin-3-O-glucoside were measured by UV and HPLC respectively. The maximum yield of anthocyanins was achieved by freezing the samples for 5.43 min in liquid nitrogen at the liquid–solid ratio of 24.07:1 mL/g, followed by ultrasonic thawing at 41.64 °C for 23.56 min. The yield and antioxidant effects of ABVS extracted using FUTE, ultrasound-assisted extraction (UAE) and freeze-thawing extraction (FTE) were compared in order to determine the overall efficacy of FUTE. In addition to the higher content, FUTE extracted ABVS showed greater ability to scavenge DPPH·, ABTS⁺ and superoxide anions, and inhibit lipid peroxidation compared to the ABVS extracted by UAE or FTE. The reducing power of the FUTE-derived ABVS was intermediate between that of the UAE and FTE samples. Taken together, FUTE can rapidly and effectively extract ABVS and retain its antioxidant capacity.     

温度敏感聚(N-异丙基丙烯酰胺)/聚(乙烯醇)水凝胶的制备及性能研究

聚 (N -异丙基丙烯酰胺 ) (PNIPA)水凝胶具有温度敏感性 ,其在 33℃左右有一个相转变温度或较低临界溶解温度 (L CST) [1,2 ] .当外界温度低于 LCST时 ,PNIPA水凝胶吸水溶胀 ;而当外界温度高于L CST时 ,PNIPA水凝胶剧烈收缩失水 ,发生相分离 .这种相分离特性应用于药物的控制释放 [3] .固定化酶[4 ] 和循环吸收剂 [5] 等领域 .然而 ,通常的 PNIPA水凝胶是通过化学键交联而成的三维网络聚合物 ,很难发生解体或进行生物降解 ,其在某些特定场合 (如药物的体内释放等 )受到一定限制 .聚乙烯醇 (PVA)的亲水性和生物相容性较好 ,是…