检索结果-内蒙古大学图书馆

Preparation of drug delivery biodegradable PLGA nanocomposites and foams by supercritical CO2 expanded ring opening polymerization and by rapid expansion from CHClF2 supercritical solutions

Preparation of drug delivery biodegradable PLGA nanocomposit...

引用

Nanoscale materials science in Biology and Medicine

作者： Asandei, Alexandra D. Erkey, Can Burgess, Diane J. Saquing, Carl Saha, Gobinda Zolnik, Banu S. Institute of Materials Science Polymer Program University of Connecticut Storrs CT 06269 Department of Chemistry University of Connecticut Storrs CT 06269 Department of Chemical Engineering University of Connecticut Storrs CT 06269 School of Pharmacy University of Connecticut Storrs CT 06269

The synthesis of poly(lactic-co-glycolic acid) (PLGA) by the ring opening copolymerization of D,L-lactide and glycolide was performed at 110°C to 130°C using Sn(Oct)2 as catalyst, 1,10-decanediol as initiator in a supercritical sc-CO2 expanded medium at pressures of up to 3,500 psi. Due to the limited monomer solubility in sc-CO2 at low temperatures (70°C), only Mn = 2,500 is typically obtained. However, molecular weight increases with both temperature and sc-CO2 pressure. Thus, Mn = 13,000 (PDI = 1.28) was obtained at 110°C - 130°C even in the absence of fluorinated surfactants. Biodegradable drug delivery nanocomposites based on dexamethasone and poly(lactic acid) (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the rapid expansion of the corresponding supercritical CHClF2 solutions (110°C, 200-300 bar) in air (RESS) and in toluene (RESOLV). The RESS process leads to a broad particle size distribution (100-500 nm) while the RESOLV generates a narrower distribution centered around 100 nm and is accompanied by the formation of a few large particles, most likely due to aggregation. © 2005 materials Research Society.

关键词： Nanostructured materials

来源：评论

学校读者我要写书评

暂无评论

Nondestructive damage sensitivity and reinforcing effect of functionalized carbon nanotube and nanofiber/epoxy composites using electro-micromechanical techniques

Nondestructive damage sensitivity and reinforcing effect of ...

引用

2004 MRS Fall Meeting

作者： Park, Joung-Man Jung, Jin-Kyu Kim, Sung-Ju Kim, Dae-Sik Lee, Jae-Rock Kim, Tae-Wook Department of Polymer Science and Engineering Engineering Research Institute Gyeongsang National University Jinju 660-701 Korea Republic of Fiber Science Program Cornell University Ithaca NY 14853-4401 United States Advanced Materials Division Korea Research Institute of Chemical Technology Yusong Taejeon 305-600 Korea Republic of Composite Materials Group Korea Institute of Machinery and Materials Chanwon 641-010 Korea Republic of

Nondestructive damage sensing and load transfer mechanisms of thermal treated carbon nanotube (CNT) and nanofiber (CNF)/epoxy composites were investigated using electromicromechanical technique. Carbon black (CB) was used only for the comparison. Electromicromechanical techniques were applied to obtain the fiber damage and stress transferring effect of carbon nanocomposites with their contents. Thermal treatment and temperature affected on apparent modulus and electrical properties on nanocomposites due to enhanced inherent properties of each CNMs. Coefficient of variation (COV) of volumetric electrical resistance can be used to obtain the dispersion degree indirectly for various CNMs. Dispersion and surface modification are very important parameters to obtain improved mechanical and electrical properties of CNMs for multifunctional applications. Further optimized functionalization and dispersion conditions will be investigated for the following work continuously. © 2005 materials Research Society.

关键词： Carbon nanotubes

来源：评论

学校读者我要写书评

暂无评论

Designed Fabrication of Multifunctional Magnetic Gold Nanoshells and Their Application to Magnetic Resonance Imaging and Photothermal Therapy†

引用

Angewandte Chemie 2006年第46期118卷

作者： Jaeyun Kim Sungjin Park Ji Eun Lee Seung Min Jin Jung Hee Lee In Su Lee Ilseung Yang Jun‐Sung Kim Seong Keun Kim Myung‐Haing Cho Taeghwan Hyeon National Creative Research Initiative Center for Oxide Nanocrystalline Materials and School of Chemical and Biological Engineering Seoul National University Seoul 151‐744 Korea Fax: (+82) 2‐886‐8457 Laboratory of Toxicology College of Veterinary Medicine and BK21 Program for Veterinary Science Seoul National University Seoul 151‐744 Korea Fax: (+82) 2‐873‐1268 School of Chemistry Seoul National University Seoul 151‐744 Korea Present address: Advanced Materials Division Korea Research Institute of Chemical Technology Daejeon 305‐343 Korea Department of Radiology Samsung Medical Center School of Medicine Sungkyunkwan University Seoul 137‐200 Korea

来源：评论

学校读者我要写书评

暂无评论

Thermosetting properties of microwave-promoted heating of resol resin

Thermosetting properties of microwave-promoted heating of re...

引用

54th SPSJ Annual Meeting 2005

作者： Hashimoto, Hisaho Genno, Ami Hachisuka, Khota Ohshima, Kazuhiro Tanaka, Masataka Yamamoto, Tadahisa Kaga, Harumi Kakuchi, Toyoji Department of Science and Engineering for Materials Tomakomai National College of Technology 443 Nishikioka Tomakomai 059-1275 Japan Iwakura Chemical Industry Co. Ltd. Tomakomai 059-1364 Japan Sapporo Hokkaido 062-8517 Japan Division of Molecular Chemistry Graduate School of Engineering Hokkaido University Kita-ku Sapporo Hokkaido 060-8628 Japan

An effect of microwave-heating in the curing reaction of resol resin was studied. It was observed that microwave-heating proceeded the curing reaction of resol resin rapidly. From observation of DSC, selective proceeding of a curing reaction was confirmed by microwave-heating. Since a difference of the specific inductive capacity and the dielectric loss tangent of each constituent which construct the resol resin, the selectivity occurs to the curing reaction.

关键词： Resins

来源：评论

学校读者我要写书评

暂无评论

Nondestructive Damage Sensitivity and Reinforcing Effect of Functionalized Carbon Nanotube and Nanofiber/Epoxy Composites Using Electro-Micromechanical Techniques

引用

MRS Online Proceedings Library 2005年第1期851卷 200-205页

作者： Joung-Man Park Jin-Kyu Jung Sung-Ju Kim Dae-Sik Kim Jae-Rock Lee Tae-Wook Kim Department of Polymer Science and Engineering Engineering Research Institute Gyeongsang National University Jinju Korea Tiber Science Program Cornell University Ithaca U.S.A. Advanced Materials Division Korea Research Institute of Chemical Technology Yusong Korea Composite Materials Group Korea Institute of Machinery and Materials Chanwon Korea

Nondestructive damage sensing and load transfer mechanisms of thermal treated carbon nanotube (CNT) and nanofiber (CNF)/epoxy composites were investigated using electro-micromechanical technique. Carbon black (CB) was used only for the comparison. Electro-micromechanical techniques were applied to obtain the fiber damage and stress transferring effect of carbon nanocomposites with their contents. Thermal treatment and temperature affected on apparent modulus and electrical properties on nanocomposites due to enhanced inherent properties of each CNMs. Coefficient of variation (COV) of volumetric electrical resistance can be used to obtain the dispersion degree indirectly for various CNMs. Dispersion and surface modification are very important parameters to obtain improved mechanical and electrical properties of CNMs for multifunctional applications. Further optimized functionalization and dispersion conditions will be investigated for the following work continuously.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Effects of deposition and synthesis parameters on size, density, structure, and field emission properties of Pd-catalyzed carbon nanotubes synthesized by thermal chemical vapor deposition

Journal of Vacuum Science & Technology B: Microelectronics a...

引用

Journal of Vacuum science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena 2005年第2期23卷 793-799页

作者： S. Wei W. P. Kang W. H. Hofmeister J. L. Davidson Y. M. Wong J. H. Huang Interdisciplinary Program in Materials Science Vanderbilt University Nashville Tennessee 37235 USA Department of Electrical and Computer Engineering Vanderbilt University Box 1661-B Vu Station B Nashville Tennessee 37235 USA Department of Chemical Engineering Vanderbilt University Nashville Tennessee 37235 USA Department of Materials Science and Engineering National Tsing Hua University Hsinchu 300 Taiwan Republic of China

The effects of deposition parameters and NH3 pretreatment on the size and distribution of Pd catalytic particles and subsequently their effects on the characteristics of the synthesized carbon nanotubes (CNTs) were systematically investigated. It was found that the size of Pd particles decreases and the particle density (total number of Pd particles per unit area) increases as the Pd film thickness decreases. Moreover, pretreatment of Pd film in NH3 gas promotes smaller Pd particles and higher particle density which is beneficial for CNT growth. The CNTs were synthesized by thermal chemical vapor deposition at 750 °C using methane (CH4) as the carbon source, and a mixture of Ar/H2 (80 vol %: 20 vol %) as a carrier gas with NH3 serving as a processing reagent. The incorporation of NH3 in CNT synthesis, per the specific pretreatment of catalytic film, has a distinct effect on the size and morphology of CNTs produced. The interrelation between processing, structure and emission behavior of CNTs produced with different synthesis conditions was examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and field emission measurements.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Exciplex dynamics in a conjugated polymer blend of MDMO-PPV and PCNEPV

Exciplex dynamics in a conjugated polymer blend of MDMO-PPV ...

引用

Organic Photovoltaics VI

作者： Offermans, Ton Van Hal, Paul A. Koetse, Marc M. Meskers, Stefan C. J. Janssen, René A.J. Molecular Materials and Nanosystems Department of Chemical Engineering and Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven Netherlands P.O. Box 902 5600 AX Eindhoven Netherlands TNO Science and Industry P.O. Box 6235 5600 HE Eindhoven Netherlands

The photophysical properties of a solution processed blend of two semiconducting polymers with electron donating and electron accepting properties, respectively, as used in polymer photovoltaic devices have been investigated. In the binary mixture of poly[2-methoxy-5-(3,7-dimethyloctyloxy)- 1,4-phenylenevinylene] (MDMO-PPV) and poly[oxa-1,4-phenylene-(1-cyano-1,2- vinylene)-(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene)-1, 2-(2-cyanovinylene)-1,4-phenylene] (PCNEPV) photoexcitation of either one of the polymers results in formation of a luminescent exciplex at the interface of the two materials. The high energy of this correlated charge-separated state is consistent with the high opencircuit voltage of the corresponding solar cells (1.36 eV). Application of an electric field results in dissociation of the marginally stable exciplex into charge carriers, which provides the basis for the photovoltaic effect of this combination of materials.

关键词： Polymer blends

来源：评论

学校读者我要写书评

暂无评论

Preparation of drug delivery biodegradable PLGA nanocomposites and foams by supercritical CO2 expanded ring opening polymerization and by rapid expansion from CHClF2 supercritical solutions

引用

MRS Online Proceedings Library 2005年第1期845卷 252-257页

作者： Asandei, Alexandru D. Erkey, Can Burgess, Diane J. Saquing, Carl Saha, Gobinda Zolnik, Banu S. Institute of Materials Science Polymer Program University of Connecticut Storrs USA Department of Chemistry University of Connecticut Storrs USA Department of Chemical Engineering University of Connecticut Storrs USA School of Pharmacy University of Connecticut Storrs USA

The synthesis of poly(lactic-co-glycolic acid) (PLGA) by the ring opening copolymerization of D,L-lactide and glycolide was performed at 110 °C to 130 °C using Sn(Oct)2 as catalyst, 1,10-decanediol as initiator in a supercritical sc-CO2 expanded medium at pressures of up to 3,500 psi. Due to the limited monomer solubility in sc-CO2 at low temperatures (70 °C), only Mn = 2,500 is typically obtained. However, molecular weight increases with both temperature and sc-CO2 pressure. Thus, Mn = 13,000 (PDI = 1.28) was obtained at 110 °C–130 °C even in the absence of fluorinated surfactants. Biodegradable drug delivery nanocomposites based on dexamethasone and poly(lactic acid) (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the rapid expansion of the corresponding supercritical CHC1F2 solutions (110 °C, 200–300 bar) in air (RESS) and in toluene (RESOLV). The RESS process leads to a broad particle size distribution (100–500 nm) while the RESOLV generates a narrower distribution centered around 100 nm and is accompanied by the formation of a few large particles, most likely due to aggregation.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Frequency domain photon migration in the δ−P1 approximation: Analysis of ballistic, transport, and diffuse regimes

引用

Physical Review E 2005年第2期72卷 021903-021903页

作者： J. S. You C. K. Hayakawa V. Venugopalan Department of Biomedical Engineering University of California Irvine Irvine California 92697-2715 USA Laser Microbeam and Medical Program Beckman Laser Institute University of California Irvine Irvine California 92697-3010 USA Department of Chemical Engineering and Materials Science University of California Irvine Irvine California 92697-2575 USA

The standard diffusion approximation (SDA) to the Boltzmann transport equation (BTE) is commonly used to describe radiative transport for biomedical applications of frequency-domain diffuse optical imaging and spectroscopy. Unfortunately, the SDA is unable to provide accurate radiative transport predictions on spatial scales comparable to the transport mean free path and for media in which optical scattering is not dominant over absorption. Here, we develop and demonstrate the use of the δ−P1 approximation to provide improved radiative transport estimates in the frequency domain via the addition of a Dirac δ function to both radiance and phase function approximations. Specifically, we consider photon density wave propagation resulting from the illumination of an infinite turbid medium with an embedded, intensity-modulated, spherical light source. We examine the accuracy of the standard diffusion and δ−P1 approximations relative to Monte Carlo simulations that provide exact solutions to the BTE. This comparison establishes the superior accuracy of the δ−P1 approximation relative to the SDA that is most notable at distances less than 3 transport mean free paths from the source. In addition, we demonstrate that the differences in photon density wave propagation in a highly forward scattering medium (g1=0.95) vs an isotropically scattering medium (g1=0) provides a basis to define three spatial regimes where the light field is dominated by (a) unscattered/ballistic light, (b) minimally scattered light, and (c) diffusely scattered light. We examine the impact of optical properties, source modulation frequency, and numerical aperture of detection on the spatial extent and location of these regimes.

关键词： TURBID MEDIA IN-VIVO DENSITY WAVES STEADY-STATE OPTICAL TOMOGRAPHY LIGHTDOSIMETRY RADIATIVE TRANSPORT SCATTERING MEDIA TISSUE SPECTROSCOPY

来源：评论

学校读者我要写书评

暂无评论

Tissue engineered bone formation with polymer/ ceramic composites by press-and-baking method

Tissue engineered bone formation with polymer/ ceramic compo...

引用

作者： Jung, Youngmee Kim, Soo Hyun Kim, Sang-Soo You, Hee Jin Kim, Byoung-Soo Kim, Sukyoung Kim, Sang-Heon Kim, Young Ha Biomaterials Research Center Korea Institute of Science and Technology P.O.Box 131 Cheongryang Seoul 130-650 Korea Republic of Department of Chemical Engineering Hanyang University 17 Haengdang-dong Seongdonggu Seoul 133-791 Korea Republic of Interdisciplinary Program for Biochemical Engineering and Biotechnology Seoul National University San 56-1 Shilim-dong Kwanak-gu Seoul 151-742 Korea Republic of School of Materials Engineering Yeungnam University 214-1 Dae-dong Gyeongsangbuk-do 712-749 Korea Republic of

A novel process was developed to fabricate polymer/ceramic composites for bone tissue engineering. The mixture of polylactic acid (PLA), calcium metaphosphate (CMP), and NaCl were compressed and subsequently heated. After dissolving the NaCl salts, porous biodegradable polymer/ceramic composite scaffolds were formed. The characteristics of the scaffolds were compared to those of scaffolds fabricated using a conventional solvent casting method, in terms of pore structure, pore size distribution, and mechanical properties. The scaffolds were seeded by osteoblasts and cultured in vitro or implanted into nude mice subcutaneously for up to 5 weeks. Cells were better grown to form tissue-like structures on CMP/PLA composites fabricated by the Press-and-Baking method. In addition, the alkaline phosphatase activity of and calcium deposition in the scaffolds explanted from mice were enhanced significantly for the scaffolds by Press-and-Baking compared to them by solvent casting. Taken together, these results suggest that CMP promote cell differentiation and proliferation via direct interaction with cells in the CMP/PLA composites. This novel PLA/CMP composite will be applicable for bone tissue engineering to support and cell differentiation and growth.

关键词： Polymer matrix composites

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：