Tris(dithiocarbamato)iron(III) complexes as precursors for iron sulfide nanocrystals and iron sulfide-hydroxyethyl cellulose composites

Iron(III) complexes of dimethyldithiocarbamate and imidazolyl dithiocarbamate were synthesized and characterized by elemental analyses, FTIR, UV–VIS and the ligands by NMR spectroscopy. The complexes were thermolysed as single molecule precursors at 180°C to prepare octadecylamine (ODA) capped iron sulfide nanocrystals and iron sulfide-hydroxyethyl cellulose (HEC) composites. UV–VIS, PL, FTIR, P-XRD, HRTEM, FESEM and EDS were used to characterize the iron sulfide nanocrystals and corresponding HEC nanocomposites. XRD confirmed iron sulfide nanocrystal (NP1) from dimethyldithiocarbamate to be hexagonal pyrrhotite-5H, Fe₉S₁₀ crystalline phase while iron sulfide nanocrystals (NP2) from imidazolyl dithiocarbamate is in pyrrhotite, Fe₁₁S₁₂ crystalline phase. TEM images show that the iron sulfide nanocrystals have particle sizes in the range 24–32?nm for NP1 and 18–25?nm for NP2 iron sulfide nanocrystals. The optical band gaps of the iron sulfide nanocrystals obtained from Tauc plots are 3.83 and 4.16?eV for NP1 and NP2, respectively. IR spectra, FESEM surface morphology and EDS spectra of iron sulfide/HEC composites confirmed dispersion of the iron sulfide nanocrystals within the hydroxyethyl cellulose (HEC) matrix.     

HEC-HMS模型在紫荆关流域水文模拟中的应用

水文模拟对于流域防洪减灾、水资源规划管理有重要意义。基于Aster GDEM2提取紫荆关流域特征,并利用HEC-GeoHMS构建流域HEC-HMS模型。采用初损后损法、Clark单位线、马斯京根法和指数退水曲线法进行产汇流计算,模拟紫荆关流域1980~1988年16场次洪,其中前11场次洪用于率定,其余5场次洪作为验证。结果表明,HEC-HMS模型在紫荆关流域水文模拟中模拟效果较好,率定期的确定性系数在0.762~0.932之间,验证期的确定性系数在0.706~0.890之间,验证了该模型在我国半湿润地区大中流域应用的可行性。     

Chitosan—A versatile semi-synthetic polymer in biomedical applications

This review outlines the new developments on chitosan-based bioapplications. Over the last decade, functional biomaterials research has developed new drug delivery systems and improved scaffolds for regenerative medicine that is currently one of the most rapidly growing fields in the life sciences. The aim is to restore or replace damaged body parts or lost organs by transplanting supportive scaffolds with appropriate cells that in combination with biomolecules generate new tissue. This is a highly interdisciplinary field that encompasses polymer synthesis and modification, cell culturing, gene therapy, stem cell research, therapeutic cloning and tissue engineering. In this regard, chitosan, as a biopolymer derived macromolecular compound, has a major involvement. Chitosan is a polyelectrolyte with reactive functional groups, gel-forming capability, high adsorption capacity and biodegradability. In addition, it is innately biocompatible and non-toxic to living tissues as well as having antibacterial, antifungal and antitumor activity. These features highlight the suitability and extensive applications that chitosan has in medicine. Micro/nanoparticles and hydrogels are widely used in the design of chitosan-based therapeuticsystems. The chemical structure and relevant biological properties of chitosan for regenerative medicine have been summarized as well as the methods for the preparation of controlled drug release devices and their applications.     

Influence of plasticizer contents on the properties of HEC-based solid polymeric electrolytes

Solid polymeric electrolytes were obtained by the plasticization process of hydroxyethylcellulose (HEC) with different quantities of glycerol and addition of lithium trifluoromethane sulfonate (LiCF₃SO₃) salt. The samples were prepared in the form of transparent films with very good adhesion properties. These films were characterized by X-ray diffraction, thermal analysis (DSC) and UV-NIR spectroscopy. The ionic conductivity measurements were obtained by impedance complex spectroscopy as a function of both salt contents and temperature. The best conductivity values of 1.07 × 10⁻⁵ S/cm at 30 °C and 1.06 × 10⁻⁴ S/cm at 83 °C were obtained for the samples of HEC plasticized with 48% of glycerol and containing [O]/[Li] = 6. These results show that plasticized HEC is a very good material to be used for the preparation of new solid polymeric electrolytes.     

Operation of the IR-8 reactor with IRT-3M type fuel assemblies

The main features of the IR-8 reactor developed at the Russian Research Center ‘Kurchatov Institute' for investigations in nuclear physics, solid state physics, radiation chemistry, radiobiology as well as for radioisotopes production are described. The features of the IRT-3M type fuel assemblies (FAs) used in the IR-8 and other reactors are described. Data on the IRT-3M type FAs operation experience, confirming their high reliability up to average (by FA volume) burnup of uranium-235 (U-235) as >60%, are adduced.     

中国先进加工制造工艺与装备技术中的关键科学问题

根据中国国家自然科学基金委员会安排，研讨先进加工制造工艺与装备科学与技术的发展趋势。针对中国先进加工制造和装备学科存在的基础研究不系统、不深入的共性状况，以国家需求为目标，以加强先进制造工艺与装备的理论基础研究和应用基础研究为突破口，提出国家自然科学基金“十一五”(2006～2010)期间先进加工制造工艺和装备领域需要研究的科学问题、研究方向、工程目标，以及应该优先发展的重点方向。 先进加工制造是实现高效率、高精度和低成本制造的技术支撑。先进加工制造的目标是高效化、精密化、智能化、集成化、数字化和洁净化，关键技术包括高速/高效切削加工技术、高速/超高速磨削技术、精密/超精密加工技术、非传统加工及其复合加工技术，以及相关的先进加工制造装备的制造技术。 摘要根据中国国家自然科学基金委员会安排，研讨先进加工制造工艺与装备科学与技术的发展趋势。针对中国先进加工制造和装备学科存在的基础研究不系统、不深入的共性状况，以国家需求为目标，以加强先进制造工艺与装备的理论基础研究和应用基础研究为突破口，提出国家自然科学基金“十一五”(2006～2010)期间先进加工制造工艺和装备领域需要研究的科学问题、研究方向、工程目标，以及应该优先发展的重点方向。 先进加工制造是实现高效率、高精度和低成本制造的技术支撑。先进加工制造的目标是高效化、精密化、智能化、集成化、数字化和洁净化，关键技术包括高速/高效切削加工技术、高速/超高速磨削技术、精密/超精密加工技术、非传统加工及其复合加工技术，以及相关的先进加工制造装备的制造技术。 高速/高效切削加工技术的科学问题包括切削加工时刀具和工件材料相互作用过程刀具摩擦、磨损和破坏机理，工件材料高速切削变形理论与工件表面成形机理，高速切削刀具与机床的动力学分析，高速切削过程的智能监控理论与技术。研究方向包括高速/高效切削机床与刀具，难加工材料的高速/高效切削加工，高速/高效切削表面质量，高速/高效切削加工的动力学与稳定性。工程目标包括超高速切削，机床主轴转速达到1×106r·min-1，铣削铝及其合金的切削速度达到1×104m·min-1；高性能切削，机床主轴功率达到100kW，进给速度达到50m·min-1；采用多坐标驱动，提高机床的柔性和效率。     

CVI处理短碳纤维在CFRC中分散性的评价

碳纤维增强水泥基复合材料(CFRC)是一种新发展起来的、很有潜力的功能材料.丙烯作前驱体,对短碳纤维在高温下(900～1300℃)进行100个小时左右的化学气相浸渍(CVI)表面处理,丙烯在高温下分解,生成热解碳,沉积在碳纤维表面.借助超声波预分散技术及新型分散剂羟乙基纤维素(hydroxyethyl cellulose,HEC)和超细颗粒硅灰的分散作用,实现了CVI处理碳纤维在水泥基体中的均匀分散.HEC水溶液的质量分数控制在1.56～1.77%之间为宜.分别运用扫描电镜法(SEM)、新拌料浆法(FM)、硬化试件电阻率测试法(ERM)及模拟试验法(SE)四种方法评价了CVI处理后短碳纤维的分散性.每种方法均有自身的优缺点和适应环境,四种方法中,模拟试验法(SE)是评价制备CFRC复合材料前期、碳纤维第一步分散的最方便的方法,此法不仅可节约时间和大量的原材料,而且可预测制备CFRC过程中应选择何种分散剂及碳纤维第二步分散的情况.     

HEC煤层压裂液的性能评价及应用

结合煤层孔隙度小、渗透性差等物性特征,对压裂液配方进行 经,筛选出适合煤层物性的ＨＥＣ压裂液,并对其性能进行了评价。研究表明,ＨＥＣ是一种无损害压裂液,适合于低温煤层进行压裂改造,它具有增稠能力强、无残渣、易破胶返排等特点。在陕西柳林地区进行了５次现场试验,效果显著。     

Development of interpenetrating polymeric network for controlled drug delivery and its evaluation

Abstract

Polymers play vital role in drug delivery systems. Aim of current research work was to elucidate the effect of Hydroxyethyl cellulose (HEC), acrylic acid (AA) and N'N'-methylene bis-acrylamide (MBA) in formulation of pH sensitive nexus for targeted delivery of acid sensitive drug perindopril erbumine (PE). Different feed ratios were employed to prepare nexus via free radical polymerization. FTIR (Fourier transform infrared spectroscopy) depicts efficient grafting. Thermal parameters (DSC, DTA and TGA) were thermodynamically stable and morphological (SEM) analysis represented porous architecture. pH sensitivity was supported by on-off switching in acid and basic media. Hence, HEC-co-AA based design was encouraging for targeted delivery of perindopril erbumine.