壳聚糖修饰的Lysozyme-PLGA阳离子纳米药物的制备与表征

通过二环己基碳二亚胺将聚乳酸-羟基乙酸共聚物(PLGA)活化,又与溶菌酶进行化学键合,再采用单乳化-溶剂挥发技术制备表面带正电荷的壳聚糖(CHS)PLGA纳米微球。对纳米微球制备条件进行了优化。结果表明在ρ(CHS)=3 mg/mL,ρ(PLGA)=5 mg/mL,溶菌酶与PLGA的质量比为0.2的条件下,得到的纳米微球包封率为87.8%,载药量为14.7%。微球粒径φ可控制在(450±50)nm之间,在pH=4时,纳米微球表面ζ电位为42.5mV。SEM图像显示经CHS修饰的Lysozyme-PLGA的纳米微球形状规整。药物释放试验显示纳米微球在20 d后释放达到70%,且释放曲线规整。     

载有溶菌酶微球的凝胶埋植剂的释药特性

为实现生物大分子药物的体内长期缓释,将药物制成乳酸/羟基乙酸共聚物(PLGA)的微球,再将微球分散于甲基纤维素反向温敏凝胶骨架中,制成微球-温敏凝胶复合埋植剂.通过体外释放实验,考察复合体系对模型药物溶菌酶的控释效果;通过凝胶色谱和扫描电镜,考察单独的微球以及在复合体系中的微球降解过程,分析凝胶介质对微球降解特性的影响;采用Peppas经验式来描述释放机制.结果表明: 在微球-凝胶复合体系中,溶菌酶可平稳释放30 d以上,无突释;药物释放是由载体溶蚀和药物扩散作用共同控制的.     

S/O/W法制备PLGA/TiO2载药微球

将纳米TiO2吸附溶液中的BSA由水包油包固体乳化法用PLGA包裹药物粒子.通过紫外和SEM等检测手段,考察纳米TiO2在不同条件下对BSA吸附率的影响,以及不同制备工艺下PLGA包裹药物粒子对载药量和包封率及体外释放的影响.研究结果表明,当溶液的pH值接近蛋白质等电点、温度在20 ℃左右、反应24 h时,TiO2吸附BSA量最大,药物粒子分布均匀,尺寸在40 nm左右.在制备微球时,当初乳体积降低、PVA浓度降低及PLGA与药物粉末的质量比增大时,载药量和包封率都有提高,且微球体外释放较小.微球表面光滑,尺寸为4 μm左右.     

氟苯尼考/壳聚糖纳米微球的制备及其缓释性能

以三聚磷酸钠为交联剂,采用离子交联法制备了氟苯尼考/壳聚糖纳米微球,用激光粒度分析仪、扫描电镜表征了该纳米微球的微观结构和形态,并通过Zeta电位和红外光谱分析该载药纳米微球的形成机理.结果显示:当氟苯尼考与壳聚糖的质量分数为3∶5、壳聚糖与三聚磷酸钠的质量分数为5∶1时,氟苯尼考/壳聚糖纳米微球对氟苯尼考有较大的包封率(64.5%)和载药量(44.0%),并具有较好的缓释性能(45.5 h内释放79.2%),作为氟苯尼考的缓释剂型是可行的.药物释放曲线符合一级动力学方程.     

新型W/O/O法BSA/PLGA微球的制备、表征及体外细胞活性的研究

选用牛血清白蛋白(BSA)为模型药物,聚乳酸-聚乙羟基醇共聚物(PLGA)为药物载体,通过水/油/油(W/O/O)新型凝聚法进行BSA/PLGA缓释微球的制备,考察PLGA的浓度、分子量、二氯甲烷(DCM)和硅油体积比、搅拌转速、固化溶剂及干燥方式等各个因素对制备过程的影响,并对其形貌、粒径、载药量和包封率等进行分析与表征,从而确定最佳的BSA/PLGA缓释微球的制备处方和工艺.结果表明:微球圆整均匀、平均粒度是75μm,包封率达85%;红外扫描图显示PLGA和BSA分子之间形成新的氢键,BSA被包裹在PLGA微球中;DSC图谱显示BSA被包裹在其中呈无定型状态;体外细胞活性实验中,3T3的细胞活性在80%以上,具有安全性.通过W/O/O新型凝聚法制备BSA/PLGA缓释微球的工艺较为稳定,包封率较高,载药量为4.58%.     

SPG膜乳化法制备载蛋白的CA-gel/PLGA复合微球

采用SPG膜乳化法,在PLGA微球的制备基础上,利用Sa与Ca~(2+)螯合形成难溶于水的CA-gel原理,以粒径、载药量、包封率、体外释放行为等作为评价指标,研究制备载蛋白药物的CA-gel/PLGA复合微球的新工艺,并对比复合微球和PLGA微球的载药释药特性的差异。与PLGA微球相比,复合微球的载药量由6.94%增加至8.35%,包封率由62.47%增加至75.16%,突释率由42.32%下降至30.84%。复合微球在经历早期的突释之后以较为均匀的速度缓慢持续释放药物,与PLGA微球相比,2~40 d的累积释放量由31.76%增加至40.29%。两者的释药曲线均符合Peppas-Sahlin方程(R~20.99),表明释药机制是扩散和溶蚀协同作用。采用扫描电镜观察到复合微球的结构更为致密,表面孔洞数量及面积明显减小,将其冷冻切片后观察到近表面的孔洞较少,平面孔隙率及孔隙数量均减小。激光共聚焦结果显示,更多的蛋白药物被包裹在复合微球内部,其荧光强度明显增强。表明CA-gel/PLGA复合微球能有效提高载药量和包封率,降低突释率,使微球后期释药增加。     

那格列奈壳聚糖微球的制备及其释放性能

采用乳化分散-化学交联法,以那格列奈(nateglinide)为模型药物,戊二醛为交联剂,制备了那格列奈壳聚糖微球,考察各种条件对所制备微球的理化性质和药物释放性能的影响.结果表明,所得微球球形规整,粒度分布均匀,呈黄褐色,平均粒径2.054 m,载药量为9.12%,药物包封率达48.9%.XRD分析结果表明,微球内部药物主要以无定形聚集态存在.体外模拟释放结果表明,微球有良好的平稳缓释性能.其释药速率随着壳聚糖浓度增大而减慢,在酸性介质中略大于在弱碱性介质中.     

海藻酸钠/壳聚糖缓释微球的制备及性能

利用海藻酸钠(SA)聚阴离子及壳聚糖(CS)聚阳离子电解质的性质,以顺铂(DDP)为模型药,采用乳化交联法制备海藻酸钠-DDP缓释微球,根据静电吸附原理合成SA/DDP/CS复合载药微球.研究微球对药物分子的包载能力及释药特性.结果显示,制备的微球圆整,载药微球表面致密且分散性好,微球粒径在11.0～58.8μm之间,采用原子吸收分光光度计对载药微球的载药率、药物包封率和药物体外释放性质进行了测试和分析,结果表明载药微球缓释效果明显,减少了药物的投放量和投放次数,降低了毒副作用.     

PLGA基载药复合微球的制备及其释放性能

以聚乳酸-羟基乙酸(PLGA)为载体材料,牛血清蛋白(BSA)为蛋白模型药物,采用复相乳化溶剂法制备PLGA载药微球,探索载药微球制备过程中囊芯比、初乳水油比、分散剂浓度、超声乳化时间对微球粒径大小、载药率、包封率的影响。结果表明,最优载药微球的制备条件为:囊芯比1:1,初乳水油比3:5,分散剂质量分数0.5%,超声乳化时间2 min。在此条件下,所得PLGA微球的粒径为268.7 nm,载药率30.88%,包封率46.95%; 电镜照片表明微球表面连续光滑,粒径分布较均匀。采用静电吸附法用阳离子聚电解质壳聚糖对最佳条件下的PLGA载药微球进行表面修饰,扫描电镜表明复合后微球粒径变大,能谱分析表明复合后微球中有N元素存在,即复合微球中存在壳聚糖,电荷测试表明微球表面带正电; 体外释放实验表明PLGA-CS复合载药微球的缓释时间延长,释药初期的突释性明显改善。     

基于高压静电技术的戊唑醇/乙酸纤维素缓释剂的制备与性能研究

以戊唑醇(TBA)为模型药物,可生物降解的乙酸纤维素(CA)为载体材料,利用高压静电技术,制备了载药微球和载药纳米纤维缓释剂,并对载药微球和载药纳米纤维的释放过程进行了研究,同时采用扫描电子显微镜、红外光谱仪对载药微球和载药纳米纤维的结构和形貌进行了表征。结果表明,在缓释剂制备过程中,CA溶液浓度对载药缓释剂的形貌有较大的影响,CA溶液质量分数为4%时,制得的缓释剂为球形结构; CA溶液质量分数为15%时,制得的缓释剂为纳米纤维结构。载药微球和载药纳米纤维均具有一定的缓释性能,对白色念珠菌具有明显的抗菌效果。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.