固溶温度对亚稳β钛合金Ti-4Mo-6Cr-3Al-2Sn的组织和拉伸性能的影响

对自主设计的新型亚稳β钛合金Ti-4Mo-6Cr-3Al-2Sn(%,质量分数)在不同温度进行固溶和固溶时效处理,观察其显微组织和测试室温拉伸性能。结果表明：随着固溶温度的提高固溶态组织中的初生α相减少,当固溶温度高于相变点后初生α相完全消失,几乎全部为明显长大的粗大β晶粒。固溶温度为900℃的固溶态合金具有良好的强度和塑性匹配,屈服强度为898.7 MPa、抗拉强度为962.5 MPa、断裂伸长率为12.7%。在不同温度固溶处理的时效态合金,均析出了细小的次生α相。固溶温度低于相变点时,在初生α相间析出的细小次生α相呈60°或者平行交错排列;固溶温度高于相变点时初生α相几乎完全消失,随着固溶温度的提高析出的次生α相片层间距变大并粗化。在所有固溶温度下,时效态组织中沿原始β晶界处均析出了连续的晶界α相,合金的塑性均较差。经过750℃/0.5 h固溶和500℃/4 h时效的合金具有良好的强度和塑性匹配,其抗拉强度为1282 MPa,屈服强度为1210.6 MPa,断裂伸长率为5.3%。     

不同时间尺度的慢变量引起的簇放电研究

本文基于两个重要的慢负反馈机制给出了一个组合型的胰腺β-细胞模型.在这个模型中,不同簇放电模式对快、中、慢的振荡周期具有鲁棒性,这样可以通过快振荡周期簇放电模式的快慢动力学分析得到所有簇放电的动力学机理和拓扑类型.对于快振荡周期的簇放电,较慢的慢变量α几乎为常数,较快的慢变量Cer对快子系统没有影响,因此只要考虑慢变量...     

高离子传导纳米多孔β-Li3PS4固态电解质的湿化学法制备

利用湿化学法,并采取逐步加热脱除沉淀中四氢呋喃分子的方式,制备具有高离子电导率和低活化能的纳米多孔β-Li 3PS 4固态电解质。利用同步热分析、X射线衍射、扫描电镜、拉曼光谱、氮气吸脱附和交流阻抗测试等手段研究不同处理阶段产物的形貌、结构和物相组成,并测试分析β-Li 3PS 4固态电解质的电化学性能。结果表明:采用该方法制备的纳米多孔β-Li 3PS 4固态电解质比表面积为 28.3m 2·g -1 ,平均孔径约23nm,电化学测试表明该电解质在20℃下的离子电导率为1.84×10 -4 S·cm -1 ,活化能为0.343eV,电子电导率为1.3×10 -8 S·cm -1 ,具有优异的电化学稳定性,与金属锂负极也具有良好的兼容性。     

Electroluminescence of a device based on europium β-diketonate with phosphine oxide complex

Rare earth (RE) ions have spectroscopic characteristics to emit light in narrow lines, which makes RE complexes with organic ligands candidates for full color OLED (Organic Light Emitting Diode) applications. In particular, β-diketone rare earth (RE³⁺) complexes show high fluorescence emission efficiency due to the high absorption coefficient of the β-diketone and energy transfer to the central ion. In this work, the fabrication and the electroluminescent properties of devices containing a double and triple-layer OLED using a new β-diketone complex, [Eu(bmdm)₃(tppo)₂], as transporting and emitting layers are compared and discussed. The double and triple-layer devices based on this complex present the following configurations respectively: device 1: ITO/TPD (40 nm)/[Eu(bmdm)₃(tppo)₂] (40 nm)/Al (150 nm); device 2: ITO/TPD (40 nm)/[Eu(bmdm)₃(tppo)₂] (40 nm)/Alq₃ (20 nm)/Al (150 nm) and device 3: ITO/TPD (40 nm)/bmdm-ligand (40 nm)/Al (150 nm), were TPD is (N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1-biphenil-4,4-diamine) and bmdm is butyl methoxy-dibenzoyl-methane. All the films were deposited by thermal evaporation carried out in a high vacuum system. These devices exhibit high intensity photo- (PL) and electro-luminescent (EL) emission. Electroluminescence spectra show emission from Eu³⁺ ions attributed to the ⁵D₀ to ⁷F_J (J = 0, 1, 2, 3 and 4) transitions with the hypersensitive ⁵D₀ → ⁷F₂ transition (around 612 nm) as the most prominent one. Moreover, a transition from ⁵D₁ to ⁷F₁ is also observed around 538 nm. The OLED light emission was almost linear with the current density. The EL CIE chromaticity coordinates (X = 0.66 and Y = 0.33) show the dominant wavelength, λ_d = 609 nm, and the color gamut achieved by this device is 0.99 in the CIE color space.     

Preparation and characterization of self nano-emulsifying drug delivery system (SNEDDS) for oral delivery of heparin using hydrophobic complexation by cationic polymer of β-cyclodextrin

Objective: The aim of this study was the preparation of a self nano-emulsifying drug delivery system (SNEDDS) for oral delivery of heparin.

Significance: Preparation of hydrophobic complexes between heparin as the hydrophilic macromolecule and cationic polymer of β-cyclodextrin (CPβCD) was considered for preparation of orally administered SNEDDS in which the drug incorporated in internal oil phase of O/W nano-droplets.

Methods: Hydrophobic complexes of heparin-CPβCD were prepared by electrostatic interaction. The lipophilic feature of complexes was characterized by determining their partition co-efficients. SNEDDS prototypes were prepared by mixing liquid paraffin, Tween 80, propylene glycol and ethanol, diluted 1:100 in an aqueous medium. Central composite response surface methodology was applied for statistical optimization. Independent variables were the amount of liquid paraffin and the amount of Tween 80, while responses were size and poly dispersity index (PdI). Optimized SNEDDS were studied morphologically using transmission electron microscopy (TEM). In vitro release of heparin was studied in the simulated gastric and simulated intestinal media.

Results: The data revealed that in molar ratio 1:3 (heparin:CPβCD), the n-octanol recovery was maximized and reached 67.6?±?11.86%. Size, PdI, zeta potential, EE% in gastric medium and EE% in intestinal medium for optimized nano-droplets were reported as 307?±?30.51?nm, 0.236?±?0.02,?+2.1?±?0.66?mV, 90.2?±?0.04 and 96.1?±?0.73%, respectively. Microscopic images revealed spherical nano-droplets. The obtained data revealed no burst release of heparin from nano-droplets.

Conclusions: The obtained results indicate that SNEDDS could be regarded as a good candidate for oral delivery of heparin as the hydrophilic macromolecule.     

Photoluminescence enhancement by isolating β-FeSi2 layers from defective layers

We have investigated an optimal annealing process in order to enhance 1.55 μm light emission from semiconducting β-FeSi₂ and found that two steps annealing at 600 °C and 800 °C is effective to its enhancement. Rutherford backscattering spectroscopy and SEM observations revealed that pronounced surface segregation of Fe atoms during annealing at 600 °C caused surface precipitate of β-FeSi₂. The enhancement of light emission is attributed spatial isolation of the surface β-FeSi₂ (light emitting layer) from damaged and defective layers with nonradiative recombination centers.     

小鼠受X射线全身照射后腹腔巨噬细胞IL-1 β蛋白表达的变化

采用胸腺细胞联合增殖反应法,观察了不同剂量Ｘ射线全身照射后小鼠腹腔巨噬细胞ＩＬ－１β蛋白生物活性的时程（７５ｍＧｙ和２．０Ｇｙ照射后６、１２、２４、４８、７２、１２０和１６８ｈ）变化和剂量效应关系（０．０７５、０．２、０．５、１．０、２．０４．０、６．０Ｇｙ照射后２４ｈ）。时程变化结果表明,７５ｍＧｙ照射后,小鼠腹腔巨噬细胞ＩＬ－１β蛋白生物活性逐渐增高,照后６、１２、２４ｈ明显高于对照组,且以照     

阿尔茨海默病药物治疗的研究进展

综述了阿尔茨海默病的药物治疗研究进展,包括乙酰胆碱酯酶抑制剂,NMDA受体拮抗剂,非甾体类抗炎药,抗氧化剂,免疫治疗以及针对Aβ的其它治疗手段等.     

作用于酪氨酸激酶的抗肿瘤小分子抑制剂γ-氟代Goniothalamin类似物的设计与合成

蛋白酪氨酸激酶在肿瘤细胞的增殖、分化、转移、侵蚀等信号通路中具有重要的调控功能,已成为肿瘤靶向治疗的重点研究对象。基于靶点导向原则和构效关系研究基础,以抗肿瘤活性天然产物Goniothalamin为母体化合物,修饰合成了一系列γ,γ-二氟取代Goniothalamin类似物（4a-4i,6a-6i）和γ-单氟取代Goniothalamin类似物（7a,7b,7h）。γ,γ-二氟取代的Goniothalamin类似物可从具有光学活性的二氟亚甲基取代的锡试剂出发,经Stille偶联和1,5-氧化关环两步关键反应合成。γ-单氟取代Goniothalamin类似物则经Sharpless不对称环氧化、环氧开环亲核氟化、Lindlar氢化、HWE反应和1,5-氧化关环等反应制备。对所合成的这两类Goniothalamin含氟类似物进行了体外肿瘤细胞抑制活性和酪氨酸激酶抑制活性评估研究,结果表明在Goniothalamin分子的γ位引入一个氟原子进行修饰是较为合理的修饰方式。     

A review of natural antioxidants and their effects on oxidative status, odor and quality of fresh beef produced in Argentina

Meat derived from pasture feeding, is associated with a high level of antioxidants. Antioxidants are incorporated within cell membranes and protect tissues against oxidation from reactive oxygen species. This maintains the overall quality of meat and secondary products. This paper reviews the implications of incorporating natural antioxidants into fresh beef, focusing on the benefits of feeding cattle good quality pasture. Pasture samples typically have higher levels of α-tocopherol, β-carotene, ascorbic acid and glutathione than feedlot samples. These compounds retard lipid and protein oxidation in fresh and stored meat, and preserve the color and odor quality of beef. The significance of antioxidant enzymes is variable, because their behavior depends on individual redox status before slaughter. Understanding total antioxidant activity requires information on antioxidant and pro-oxidant status. With an abundance of pasture, Argentina has a natural advantage in producing meat with a high antioxidant value.