Molecular Clues to Understanding Causes of Human-Assisted Reproduction Treatment Failures and Possible Treatment Options

More than forty years after the first birth following in vitro fertilization (IVF), the success rates of IVF and of IVF-derived assisted reproduction techniques (ART) still remain relatively low. Interindividual differences between infertile couples and the nature of the problems underlying their infertility appear to be underestimated nowadays. Consequently, the molecular basis of each couple’s reproductive function and of its disturbances is needed to offer an individualized diagnostic and therapeutic approaches to each couple, instead of applying a standard or minimally adapted protocols to everybody. Interindividual differences include sperm and oocyte function and health status, early (preimplantation) embryonic development, the optimal window of uterine receptivity for the implanting embryo, the function of the corpus luteum as the main source of progesterone production during the first days of pregnancy, the timing of the subsequent luteoplacental shift in progesterone production, and aberrant reactions of the uterine immune cells to the implanting and recently implanted embryos. In this article, the molecular basis that underlies each of these abnormalities is reviewed and discussed, with the aim to design specific treatment options to be used for each of them.     

Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics

The structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular dynamics and metadynamics) methods. Single crystals of D4 were grown in a glass capillary in situ and the structures of high- (238–270 K) and low-temperature (100–230 K) phases were studied in detail. In the temperature interval 230–238 K, a phase transition with rather low enthalpy (−1.04(7) kcal/mol) was detected. It was found that phase transition is accompanied by change of conformation of cyclosiloxane moiety from boat-saddle (cradle) to chair. According to PBE0/6-311G(d,p) calculation of isolated D4, such conformation changes are characterized by a low barrier (0.07 kcal/mol). The character of molecular thermal motion and the path of phase transition were established with combination of periodic DFT calculations, including molecular dynamics and metadynamics. The effect of crystal field led to an increase in the calculated phase transition barrier (4.27 kcal/mol from low- to high-temperature phase and 3.20 kcal/mol in opposite direction).     

R134a气体水合物蓄冷实验研究

以Ｒ１３４ａ为工质,对温－压相图进行了校核,对水合物的生成和融解进行了观察,对正丁醇含量对水合物的影响进行实验研究,确定Ｒ１３４ａ作为气体水合物蓄冷工质的可行性。     

顶空固相微萃取和同时蒸馏萃取用于兔肉挥发性风味成分分析的比较研究

采用顶空固相微萃取法（head space-solid phase micro-extraction,HS-SPME）和同时蒸馏萃取法（simultaneous distillation extraction,SDE）提取兔肉中的挥发性风味物质,经气相色谱-质谱联用仪分析,共检测出风味化合物47种,其中烃类最多,有17种,其次是醛类14种和醇类6种,另外有酯类5种,醚类2种,酸类1种,酮类1种,杂环类1种。HS-SPME法和SDE法分别鉴定出23种和26种挥发性组分,比较两种提取方法可知,SDE法能萃取到更多的挥发性化合物,适合对高沸点,低挥发性物质的分离;HS-SPME法快速简便、更接近真实挥发风味,适合易挥发性化合物的检出。      

镍铁矿选择性还原焙烧相变研究

对镍铁矿原料及不同温度还原焙砂进行矿物学研究,探究镍铁矿选择性还原焙烧发生的相变.研究结果表明：镍铁矿主要金属矿物为褐铁矿,其次为赤铁矿;Ni在不含锰的铁矿物中分布较均匀,而在含Mn的铁矿物中分布相对集中,并与Mn伴生.镍铁矿在还原焙烧过程中Fe、Ni和Co随温度升高逐渐发生还原、相转化和迁移富集的过程.选择性还原焙烧必须严格控制焙烧温度,要达到Ni、Co和Fe的选择性还原并形成Ni高、Fe低的合金相和磁铁矿,焙烧温度采用750℃较合适,在该温度下形成的合金相组成为55.55% Ni、9.86% Co及33.99% Fe,Ni的金属转化率为88.49%,铁氧化物主要为磁铁矿.     

ZrO2增韧Al2O3复相陶瓷中氧化锆相分布的分形维数

研究了氧化锆增韧氧化铝复相陶瓷中氧化锆相分布的分形维数随氧化锆含量、烧结温度、保温时间的变化规律,通过与该材料的力学性能比较,该变化规律不但反应了相分布特征,而且与力学性能的变化规律一致。提出了利用相分布的分形维数作为一个参量来定量分析相分布对力学性能的影响的可能性。     

铁饱和条件下铁与Fe2O3间的固相反应

采用扩散偶的方法,对铁与Fe₂O₃间的固相反应进行了研究,结果表明,两者间的产物层主要在Fe₂O₃一侧形成,而且与铁在空气中氧化不同,呈现出混合状结构;在铁饱和的条件下,Fe₂O₃转化的最终产物是Fe_xO(x<1)。     

硬质合金热处理和钴粘结相的转变温度

本工作证实WC-Co系硬质合金通过热处理可以提高其抗弯强度。所增加的抗弯强度决定于合金中钴的含量,钴含量越高的合金,其抗弯强度的增加重也就越多。主要是由于淬火热处理抑制了高温稳定的面心立方钴相转变成密排六方钴相。
本实验还采用差热分析仪测定了WC-Co系合金在加热过程中,密排六方钴相转变成面心立方钴相的相变温度。发现其相变温度随合金中钴含量的增加而升高,如YG8是742℃,YG15是770℃,YG20是821℃,这是由于高钴合金的粘结相在升温过程中有较高的钨含量。
本实验中还发现,烧结后低钴硬质合金要高于高钴硬质合金的粘结相中的钨含量,因为低钴硬质合金的烧结温度通常是高于高钴硬质合金,一般说来烧结温度越高,则粘结相中的钨含量也就越高,但当烧结态硬质合金再一次加热时,其钴结相中的钨含量要增加。所以淬火后高钴硬质合金的粘结相中的钨含量甚至比低钴硬质合金的粘结相中的还要高,这就是为什么钴粘结相由密度六方转变成面心立方的温度随硬质合金中钴含量的增加而提高。     

Ge-Si二元合金系的热力学

利用作者提出的二元相图数据计算活度的计算机程序CABPD(Calculating Activities from Binary Phase Diagrains),计算得到此体系液相及固相的热力学性质。表明此体系液、固相都呈正偏差,可以表示为:
E_Gm(L)=7125X_SiX_Ge(J/mol)
E_Gm(S)=4808X_SiX_Ge(J/mol)     

Interfacial Phase in Ti-5Al-2Mo-3Zr Alloy

Under appropriate cooling condition, intcrfacial phase appeared between α and β phases in Ti-5Al-2M0-3Zr alloy. Its thickness could reach 100 nm. The interfacial phase was either single layer structure or double layer structure. The monolithic layer adjacent to 3 phase was indentified as fee structure with relationship （110）_β// （001）_m, [11$\\mathop 1\\limits^{{\\rm{ - - }}} $]_β /[110]_m. The striated layer adjacent to a phase was indentified as hep with twin relationship {10$\\bar 1$1}<1$\\bar 0$12> to α. Thus, the study provided a new experimental fact for the controversial topic on structure of striated layer. Chemical composition of interfacial phase varied slightly with heat treatments, but always between that of α and β phases.