Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films

Strontium titanate-based materials with ferroelectric or relaxor-like properties have drawn vast attention as polar dielectrics for electronics and telecommunications. Here, we study the lattice dynamics in sol–gel-derived Sr_1−1.5xBi_xTiO₃ thin films with x = 0.0053 and 0.167, deposited on Al₂O₃ substrates, using a variable-temperature far-infrared spectroscopy in a transmittance mode. Bi doping, known to induce a low-frequency dielectric relaxation in SrTiO₃ (ST) ceramics and films, due to off-centre dopant ion displacements generating electric dipoles, is shown to affect the polar phonon behaviour of thin films. We show that in weakly Bi-doped films, the low-frequency polar TO1 mode softens on cooling but less than in undoped ST. In heavily Bi-doped ST films, this mode displays no significant frequency variation with temperature from 300 to 10 K. The polar phonon behaviour of polycrystalline Bi-doped ST thin films is comparable with that of Bi-doped ST ceramics, which exhibit dielectric relaxations and harden soft-mode behaviour instead of the ferroelectric phase transition.     

张力带固定与下极切除治疗髌骨下极骨折

目的：对比张力带固定与下极切除治疗髌骨下极骨折的疗效。方法：手术治疗髌骨下极新鲜骨折８９例,其中张力带固定４９例,下极切除４０例,术后平均随访１１个月,并根据陆氏标准评价疗效。结果;张力带固定组４５例达到优良标准,下极切除组２８例达到优良标准,张力带固定组疗效显著优于下极切除组。     

熊胆粉不同极性部位HPLC指纹图谱及化学模式识别研究

目的 建立熊胆Fel Ursi粉不同极性部位的HPLC指纹图谱,比较不同提取部位化学成分之间的差异,为全面评价熊胆粉的质量评价提供参考。方法 将熊胆粉分别用醋酸乙酯、三氯甲烷、丙酮、无水乙醇、乙腈依次提取,浓缩干燥,用甲醇溶解,建立HPLC指纹图谱,并采用相似度评价系统软件进行数据分析。结果 10批熊胆粉醋酸乙酯部位共有模式共标记6个共有峰,三氯甲烷部位共有模式共标记8个共有峰,丙酮部位共有模式共标记8个共有峰,乙腈部位共有模式共标记10个共有峰,乙醇部位共有模式共标记16个共有峰,5种溶剂提取物均指认了4个共有指纹峰（牛磺熊去氧胆酸、牛磺鹅去氧胆酸、熊去氧胆酸、鹅去氧胆酸）。综合聚类分析和主成分分析（principal component analysis,PCA）结果,发现相同产地的熊胆粉,受不同厂家加工方法不同的影响,也存在一定的质量差异。通过正交偏最小二乘-判别分析（orthogonal partial least squares- discriminant analysis,OPLS-DA）,发现牛磺熊去氧胆酸、牛磺鹅去氧胆酸、熊去氧胆酸、鹅去氧胆酸、乙醇部位10号峰、乙腈部位1、2号峰可能是熊胆粉质量差异的主要标志性成分。结论 所建立的HPLC指纹图谱可以反映熊胆粉的化学成分分布,为熊胆粉的整体质量评价提供参考,并为熊胆粉谱效关系研究提供一定依据。     

逍遥散超临界CO2提取工艺及提取物GC-MS特征图谱初步研究

该文为了初步确定逍遥散超临界CO₂提取的最佳工艺条件,并建立提取物的气相色谱-质谱（GC-MS）特征图谱,以提取物得率为考察指标,采用正交试验设计方法,对提取压力、提取温度、CO₂流量、提取时间等因素进行考察;采用GC-MS对不同批次的提取物进行特征图谱分析。逍遥散超临界CO₂提取的最佳工艺条件为提取压力20 MPa,提取温度50 ℃,CO₂流量25 kg·h^-1,提取时间3 h,提取物平均得率2.2%。GC-MS特征图谱中确定27个共有峰,占总峰面积的81.89%,其中指认出21个化合物,占提取物总量的53.20%。超临界CO₂萃取工艺合理可行,GC-MS方法准确可靠,重复性好,可用于逍遥散超临界CO₂提取物的制备及质量控制。     

宁夏大蓟提取物不同极性部位对5种革兰阴性菌的体外抑菌活性研究

目的:观察宁夏大蓟提取物的不同极性部位对5种革兰阴性菌体外抑菌活性作用。方法:大蓟水提取物、大蓟正丁醇提取物、大蓟乙酸乙酯提取物用试管二倍稀释法联合琼脂平板法,进行体外抑菌试验研究。结果:大蓟水提取物、大蓟乙酸乙酯提取物对5种革兰阴性菌最小抑菌浓度(MIC)均为﹥1.00 mg.mL-1;大蓟正丁醇提取物对5种革兰阴性菌有抑菌作用,对大肠杆菌、铜绿假单胞杆菌MIC均为1.0mg.mL-1;对伤寒沙门菌、变形杆菌、福氏痢疾杆菌MIC均为0.5mg.mL-1。结论:大蓟正丁醇提取物对5种革兰阴性菌有抑菌作用,大蓟水提取物、大蓟乙酸乙酯提取物无抑菌作用。     

远程医疗在北极地区的使用现状及可行性分析

本文对远程医疗在极地以及海上医疗服务中的应用现状进行综述,分析了北极地区及海上紧急环境中实施远程医疗的可行性及存在的挑战。为极地救援中使用远程医疗服务提供参考依据。     

Modeling Tracer Diffusion Coefficients of Any Type of Solutes in Polar and Non-Polar Dense Solvents

In this work, a simple two-parameters correlation based on the Rice and Gray, Lennard-Jones, and Stockmayer theories was devised for the calculation of binary diffusion coefficients (D12) of any type of solutes at infinite dilution in polar and non-polar solvents. This equation can be relevant for systems with polar solvents, since most models in the literature fail when strong intermolecular forces predominate in solution. The new correlation embodies the Stockmayer potential without requiring the dipole moments of any component, which significantly enlarges its application. It was validated with the largest D12 database of polar and non-polar dense systems, with 8812 data points (NDP) spanning 553 systems, of which 133 have water as solvent (NDP = 1266), 89 contain polar solvents excluding water (NDP = 1405), 177 have supercritical carbon dioxide (SC-CO2) as solvent (NDP = 5028), and 154 have non-polar or weakly polar solvents excluding SC-CO2 (NDP = 1113). Overall, the model achieved an average deviation of only 3.43%, with accurate and unbiased behavior even for polar systems.     

Using PCR in preimplantation genetic disease diagnosis.

Preimplantation diagnosis of genetic disease can be accomplished by embryo biopsy or polar body analysis using in-vitro gene amplification (PCR). PCR analysis of single cells is subject to a number of errors which decrease the reliability of the diagnosis. Using realistic assumptions about error rates based on experimental data, we analyse some of the practical consequences to be faced by whose wishing to use this diagnostic procedure. We considered both autosomal dominant and recessive diseases. We calculate the probability of making mistakes in the diagnosis, assuming a realistic range in the magnitude of PCR efficiency, cell transfer, and contamination errors. We conclude that, in general, analysing blastomeres is subject to less mis-diagnosis than polar body analysis, except in the case of dominant diseases which are caused by genes which lie extremely close to the centromere. We also show that typing multiple blastomeres from a single embryo or combining polar body typing with blastomere analysis results in significantly lower levels of mis-diagnosis with unacceptable consequences. The preimplantation diagnosis of X-linked diseases based upon Y chromosome sequence analysis is also discussed.     

Fertilization and early embryology: Recurrent failure in polar body formation and premature chromosome condensation in oocytes from a human patient: indicators of asynchrony in nuclear and cytoplasmic maturation

All oocytes from a patient who had undergone four unsuccessfulin-vitro fertilization attempts showed neither a polar bodynor pronuclei when examined for fertilization. In 19 inseminatedoocytes that were spread for karyotypic analysis, one haploidset of metaphase II chromosomes and a remarkable condensed structurewere found. Hormonal and morphological criteria implied thatthe oocytes had been mature at the time of retrieval. Sincenon-inseminated oocytes contained only one set of metaphaseII chromosomes, the condensed structure appeared to representthe sperm chromatin in the state of premature chromosome condensationdue to a block in oocyte maturation. Since the first and secondpolar body, as well as their chromatin, were undetectable inall the patient's oocytes, a rapid maturation to metaphase IIbefore retrieval and prolonged arrest in this state before fertilization,accompanied by degeneration of the first polar body, appearto be responsible for the condition. In accordance with thisnotion, degenerate spindles (typical of post-ovulatory agedoocytes) and separating chromosomes (probably representing presegregatingchromatids) were observed by antitubulin immunofluorescence.     

Polar Molecular Surface Properties Predict the Intestinal Absorption of Drugs in Humans

Purpose. A theoretical method has been devised for prediction of drug absorption after oral administration to humans. Methods. Twenty structurally diverse model drugs, ranging from 0.3 to 100% absorbed, were investigated. The compounds also displayed diversity in physicochemical properties such as lipophilicity, hydrogen bonding potential and molecular size. The dynamic molecular surface properties of the compounds were calculated, taking into account their three-dimensional shape and flexibility. Results. An excellent sigmoidal relationship was established between the absorbed fraction after oral administration to humans (FA) and the dynamic polar molecular surface area (PSA_d) (r² = 0.94). The relationship was stronger than those obtained for more established predictors of drug absorption. Drugs that are completely absorbed (FA > 90%) had a PSA_d 60 ² while drugs that are < 10% absorbed had a PSA_d > 140 ². Conclusions. The results indicate that PS Ad can be used to differentiate poorly absorbed drugs at an early stage of the drug discovery process.