聚乳酸/羟基磷灰石复合型多孔状可降解生物材料

以乳酸和乙醇酸为原料分别合成了丙交酯(LA)和乙交酯(GA)2种单体,并用单体聚合成了聚丙交酯(PLA)和丙交酯乙交酯共聚物(PLGA),结合用粉末冶金的方法制得的纳米羟基磷灰石粉末(HA),制得了聚乳酸/羟基磷灰石复合型生物可降解的多孔材料。研究结果表明,PLA和PLGA聚合物的产率同聚合过程中的氮压有关,控制造孔剂的粒度,可以得到理想的多孔材料。     

超细镍粉的制备及添加剂分散作用研究

以1,2-丙二醇和NiSO4·6H2O为原料采用液相还原法制备超细镍粉.探讨了反应温度、pH值、还原剂与NiSO4·6H2O的摩尔比及不同添加剂对镍粉粒度、形貌及分散性的影响.利用SEM、XRD、激光粒度分析仪对镍粉进行了表征.结果表明:添加剂非离子型表面活性剂聚氧乙烯失水山梨醇单油酸酯(吐温80)能有效地阻止镍粉颗粒团聚和长大,并能对镍粉进行分散,其在制备过程中的作用优于离子型表面活性剂;在反应温度为184℃左右、pH值为10、1,2-丙二醇与NiSO4·6H2O的摩尔比为1∶0.02、以聚氧乙烯失水山梨醇单油酸酯为添加剂时制得的镍粉为球形,以面心立方晶体为主,镍粉粒度分布较窄,平均粒径小于90nm.     

组织工程支架材料的制备及其孔隙性能

采用二步法制备了性能优良的生物可降解材料聚DL-乳酸（PDLLA）：第1步以DL-乳酸为原料于180～200℃、低压条件下制备出DL丙交酯（DL-LA），第2步使DL-LA于120℃真空中开环聚合生成PDLLA。制备的PDLLA的平均相对分子质量超过10万。然后利用碳酸氢钠（NaHCO3）为致孔剂制作组织工程用高分子支架材料。可以通过改变NaHCO3的用量和粒子直径来调节支架材料的孔隙率和孔隙直径，粒子用量越多，支架孔隙率越高，粒子尺寸越大，支架孔隙直径越大。经扫描电子显微镜观察，支架材料的孔隙结构为完全连通的开孔隙，孔隙直径范围为100～240μm。支架材料的最高孔隙率超过90％。     

铕-银共掺杂无机抗菌材料的制备及性能研究

将铕和金属银离子共同掺杂到白炭黑中,制得一种含稀土新型无机抗菌材料。通过单因素实验得到最佳制备条件为,铕浓度0.005 mol·L-1,反应温度90℃,反应时间1 h。在此条件下制得的铕-银共掺杂抗菌白炭黑对大肠杆菌具有很好的杀菌效果,杀菌率达98%以上。采用XRD、SEM、EDS和FTIR等手段对所制备的样品进行结构形态表征,结果表明产品为无定形态,铕以两种形态存在于材料中,一种与银共生,附着在载体白炭黑上,另一种则游离在材料中,铕和银的添加并没有明显改变白炭黑原有的结构。     

共沉淀-喷雾干燥法制备钴酸镧催化剂

以共沉淀-喷雾干燥法制备钙钛矿型LaCoO3催化剂,并比较了喷雾干燥及普通烘箱干燥对催化剂的影响。对合成的催化剂粉体进行了BET-比表面积、XRD、SEM、TPR-H2表征。结果表明,喷雾干燥所制备的前驱体在600℃焙烧即可得到单一钙钛矿相结构的催化剂粉体,形成钙钛矿结构的焙烧温度降低50℃~100℃。喷雾干燥方法制得的催化剂对甲烷燃烧反应的催化活性明显高于用普通烘箱干燥方法制得的催化剂,起燃温度为T10=394℃。     

镁热法制备高纯金属镝

对镁热法制备高纯金属镝进行了研究，结果表明：采要用高纯氯化剂氯化高纯（4N）氧化镝（Dy2O3）制取无水氯化镝（DyCl3），用镁还原无水氯化镝制得镁－镝合金，再经蒸馏制备金属镝的工艺，可以制得高纯镝，纯度可达99．99％。     

金刚石制品用Fe-Co-Cu预合金粉末的制备及其粒度控制

用共沉淀热分解法制备了用于金刚石制品的Fe-Co-Cu预合金粉.研究了共沉淀反应的pH值、温度、溶液浓度、加料顺序和速度对粉末粒度的影响,以及热分解条件对粉末粒度和含氧量的影响.用X射线衍射仪(XRD)分析粉末的物相组成,用扫描电子显微镜(SEM)观察其形貌特征.研究结果表明:采用快速并流共沉淀方式,当共沉淀反应pH值为6.5～7.0、反应温度为50～70℃、金属盐溶液A与复合沉淀剂溶液B浓度均为0.5～0.8 mol·L-1时,制得的前驱体粉末在510～550℃分解30～50 min,得到收得率高、含氧量较低、粒度适中的Fe-Co-Cu预合金粉末.     

真空开关用WCu10触头材料制备工艺的研究

用真空烧结及熔渗的方法制备了真空开关用WCu10触头材料,对两种烧结工艺制得的触头材料组织及性能进行了比较,分析、讨论了烧结工艺对材料的组织、性能的影响。结果表明,用真空高温烧结及真空熔渗工艺制备出的WCu10触头材料具有良好的综合性能,其组织均匀、致密,氧、氮含量极低,符合真空开关的使用条件,并通过了真空负荷开关的型式试验。     

表面活性剂包裹乙酰丙酮钼催化剂的制备方法及其应用

本发明涉及一种用于稠油油藏开采中，能使稠油乳化和催化降粘，增加采收率的表面活性剂包裹乙酰丙酮钼催化剂的制备方法及其应用。本发明的技术方案是：将谷氨酸二烷基酯核糖醇与氯磺酸于反应器中，恒温反应1．5—3．5h，用NaOH溶液中和，制得表面活性剂；再以乙酰丙酮和三氧化钼为原料，于水溶液中恒温反应7～12h后，     

稀土固体超强酸S2O82-/Sb2O3/La3+的制备及催化性能研究

以SbCl3为原料经醇化水解制得Sb2O3前体氧化物,通过浸渍一定量的(NH4)2S2O8和掺杂La(NO3)3制备了一种新型催化剂S2O82-/Sb2O3/La3+.以催化合成乙酸苄酯为探针反应,考察了不同制备条件对催化剂性能的影响.结果表明,1.5 mol/L的(NH4)2S2O8和2.71% La(NO3)3混合溶液浸渍锑前体氧化物,经110℃烘干后,于500℃焙烧3h所得催化剂(SSL2.71-3-500)活性较好.同时,考察了催化剂的稳定性以及对不同酯化反应的作用规律.用Hammett,IR,DTA/TGA,XRD等手段对催化剂进行了表征.     

Response of macrophages to poly(L-lactide) particulates which have undergone various degrees of artificial degradation

This investigation looked at the effects of artificially degraded poly(L-lactide) particles on macrophages in vitro. The effects of very-low-molecular-weight unprocessed poly(L-lactide) and poly(glycolide) particles were also examined. There were no obvious trends in the data, suggesting that as the artificially degraded particles became more degraded, they became more or less toxic. Comparisons of the effects of low-molecular-weight poly(L-lactide) and poly(glycolide) particles did not reveal any differences between the effects of poly(L-lactide) particles and poly(glycolide) particles on cells in vitro. It is possible that the reason for this is that the cell line used here is less sensitive to particles than cultures of primary cells. Given this information and the fact that poly(glycolide) particles have been associated with osteolytic and inflammatory problems, this would suggest that further research into poly(L-lactide) implant degradation would be worthwhile.     

Future pathways for combinatorial chemistry

Osteotomies in porotic human cadaveric humeri were fixed with metallic plates and screws in 3 experimental groups. In group I, osteotomies of the 3 arbitrarily chosen humeri were plated without reinforcement. The osteotomies of the contralateral 3 humeri were plated after reinforcement with a poly(L-lactide) augmentation device. In group II, osteotomies on one side were plated without reinforcement, but those of the contralateral humeri were plated after reinforcement with methylmethacrylate. In group III, the osteotomies of 3 humeri were plated and reinforced with poly(L-lactide) and in the 3 contralateral humeri were plated after reinforcement with methylmethacrylate. The pullout strength for screws from bones augmented with poly(L-lactide) was identical to those where methylmethacrylate had been used. The bones with poly(L-lactide) augmentation had a higher torsional stiffness than those with methylmethacrylate cement and those which were not reinforced. Resorbable polymeric medullary augmentation devices can be used to enhance plating of osteoporotic bones.     

Determination of the internal morphology of poly (D,L-lactide) microspheres using stereological methods

The morphological characteristics of the internal structure of poly (D,L-lactide) microspheres have been determined by stereological methods in two different formulations of microspheres, with different internal structures, prepared by using a double emulsion method. In one formulation the internal emulsion was produced by homogenisation at 3000 rpm, whilst the other was prepared at 11000 rpm. As expected the formulation prepared at the lower speed contained larger and more broadly distributed pores than that prepared at the higher speed. The porosity, pore size distribution and total internal surface area of the microspheres were obtained by stereological methods from electron microscopic measurements of the sectioned microspheres. It was found that whilst the porosity of the microspheres was 0.6 in both formulations, the preparation method gave rise to large differences in their pore size distribution characteristics. The pore size distribution was simulated by computer modelling to validate and compare alternative stereological algorithms. It was found that the Saltykov unfolding method predicts the measured pore size distribution more accurately than the Cruz-Orive unfolding method (at significance level alpha=0.1). This finding was attributed to the violation of one of the basic assumptions of the Cruz-Orive unfolding method.     

CpG island methylation and promoter usage in the parathyroid hormone-related protein gene of cultured lung cells

Poly-D,L-lactide (PDLLA) and polylactide-co-glycolide (PLGA) microspheres containing thymopentin have been prepared by a water-in-oil-in-water-emulsion/solvent evaporation technique. The goal is to stabilize the active compound thymopentin, and to prolong its therapeutic activity, by embedding the drug in a polymeric matrix. The microspheres obtained have been characterized for their morphology and drug content. In-vitro dissolution tests have been performed on the microspheres. Results show that the type of polymer employed (PDLLA or PLGA) does not seem to affect microsphere morphology, while in-vitro dissolution profiles are greatly influenced by the composition of polymer matrix. Ex-vivo evaluation of PLGA microspheres performed on mouse thymocites shows that biological activity of Thymopentin is maintained after loading into PLGA microspheres.     

MAGNOLOL ENTRAPPED ULTRA-FINE FIBROUS MATS ELECTROSPUN FROM POLY(ETHYLENE GLYCOL)-b-POLY(L-LACTIDE) AND IN VITRO RELEASE

Ultra-fine fibrous mats with magnolol entrapped have been prepared by eleetrospinning biodegradable copolymer poly(ethylene glycol) blocked poly(L-lactide). Drug entrapment was perfect which was confirmed by scanning electron microscopy and differential scanning calorimetry. According to in vitro drug release investigation by high performance liquid chromatography, it was found that fibers with 10%, 20% and 30% drug entrapped respect to polymer (mass ratio) presented dramatically different drug release behavior and degradation behavior under the effect of proteinase K. The reason 2 be that fibers with 10% drug entrapped was more easily affected by enzyme while, to some degree, magnolol in fibers with 20% and 30% entrapped prevented polymer from being degraded by enzyme.     

Blood pressure reactivity in the evaluation of resting blood pressure and mood responses to pindolol and propranolol in hypertensive patients

Bacterial adherence on to several materials with a potential application in reconstructive surgery was studied. Polymer (poly(L-lactide)), composite (hydroxyapatite/poly(L-lactide)) and metal (316L stainless steel) were evaluated both as smooth and sandblasted specimens. All materials were incubated in phosphate-buffered saline, challenged with Staphylococcus aureus or S. epidermidis and evaluated for up to 24 h. S. aureus showed a preference for the metal and composite tested over the polymer used. For S. epidermidis no preference was found for one of the investigated materials. The influence of surface roughness on bacterial growth was demonstrated by increased colonization on the sandblasted specimens.     

CTL responses induced by a single immunization with peptide encapsulated in biodegradable microparticles

A synthetic peptide representing a measles virus (MV) cytotoxic T cell epitope (CTL) when encapsulated in poly (D,L-lactide co-glycolide) (PLG) 50:50 microparticles induced a strong CTL response after a single intraperitoneal immunization of mice which was greater than that following administration of the peptide in Freund's complete adjuvant. A 100 micrograms dose of encapsulated peptide was shown to be more effective for CTL priming than 50 and 25 micrograms doses. A vaccine formulation prepared by simply mixing empty 50:50 PLG microparticles with the peptide resulted in the induction of CTL responses comparable to those induced by the encapsulated peptide. Moreover, a CTL response against MV-infected target cells was observed. These findings highlight the potential immunostimulatory effect of PLG microparticles for the induction of MV and peptide-specific CTL responses.     

Percutaneous intratumoral injection of cisplatin microspheres in tumor-bearing rats to diminish acute nephrotoxicity

Poly(D,L-lactide) microspheres loaded with cisplatin (PLA-CDDP MS) were prepared by a solvent evaporation technique for direct intratumoral injection. The microspheres, 50-100 microns, containing 40.04% of cisplatin produce sustained release in vitro. PLA-CDDP MS (6 mg/kg body weight of cisplatin) suspensions were injected intratumorally into mammary tumors in rats. Cisplatin solution (6 mg/kg body weight) was injected either intratumorally or intraperitoneally in two groups. After treatments, the tumor size decreased in each of the groups as a function of time. Sixteen days post-injection, the tumors had either disappeared or significantly shrunk. PLA-CDDP MS had a similar antitumor effect compared with cisplatin aqueous solution. Blood urea nitrogen, serum creatinine and histopathology examinations revealed that the renal toxicity in the PLA-CDDP MS group was significantly less than in the control groups. These results indicate that intratumoral injection of PLA-CDDP MS maintains anticancer potency and reduces acute renal toxicity.     

Biodegradable polyesters for controlled release of trypanocidal drugs: in vitro and in vivo studies

Copolymers of epsilon-caprolactone and L-lactide P(CL-LLA), epsilon-caprolactone and D,L-lactide P(CL-DLLA) and epsilon-caprolactone and trimethylene carbonate P(CL-TMC) were synthesized. The composition of comonomers and their sequence lengths were determined by means of 1H and 13C NMR measurements. The effect of the comonomer on the thermal properties was investigated by differential scanning calorimetry (DSC) analysis. The in vitro degradation of the rods obtained by melt extrusion of the synthesized copolymers and the commercial homopolymers poly(epsilon-caprolactone) P(CL) and poly(D,L-lactide) P(DLLA) was carried out in phosphate buffer (PB) pH 7.4 at 37 degrees C. The rate of degradation depends on comonomers and polymer composition. The in vitro release of the selected drugs, isometamidium chloride (IMM) and ethidium bromide (EtBr), from such devices was carried out under the same conditions as used for the in vitro degradation. The release experiments show that the release of IMM is faster than for EtBr. During the first stage, for IMM the release is governed by osmotic pressure whereas for EtBr the release is mainly diffusion-controlled. The in vitro release of these drugs is governed by polymer matrix degradation at the later stage of the release process. Comparative in vitro release study from the different polymers showed that the release depends mainly on the physical properties of the polymer. The in vivo experiments carried out in the field on cattle and in the laboratory on rabbits using the classical treatment (intramuscular injection) and the sustained release devices (SRD) subcutaneously implanted, showed that the prophylactic period is significantly enhanced in the case of SRD as compared to intramuscular injection. The comparative efficacy of SRD containing IMM and EtBr evaluated in the case of rabbits showed that, the SRD (IMM) prophylactic period is much longer than for SRD (EtBr).