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Enhancing the stability of astaxanthin by encapsulation in poly (1-lactic acid) microspheres using a supercritical anti-solvent process

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Particuology 2019年第3期17卷 54-62页

作者： Guijin Liu Man Hu Ziyi Zhao Qing Lin Dongwei Wei Yanbin Jiang School of Chemistry and Chemical Engineering South China University of Technology Guangzhou 510640 China

To improve the physicochemical properties of astaxanthin, it was encapsulated in poly (1-lactic acid)(PLLA) using a supercritical anti-solvent (SAS) process with dichloromethane/acetone mixture as the solvent, and supercritical CO2 as the anti-solvent. The effects of altering five SAS operating cond让ions, solvent ratio, temperature, pressure, concentration of carrier, and flow rate, on the microstructure of particles were investigated using an orthogonal experimental design. Under the optimal conditions, astaxanthin/PLLA particles were produced with an encapsulation efficiency of 91.5% and a mean particle size of 954.6 nm. SEM images showed that most astaxanthin/PLLA particles were uniform microspheres. FT-IR spectra showed that the chemical structure of astaxanthin was unchanged by the SAS process. The results of chromatic difference, X-ray diffraction, thermogravimetric, and differential scanning calorimetry analyses showed that astaxanthin had been encapsulated in the PLLA matrix in an amorphous state. Overall, astaxanthin/PLLA microspheres greatly enhanced the stability of astaxanthin during storage, and the levels of residual solvents were far lower than the ICH lim让s. This means that astaxanthin/PLLA microspheres prepared using SAS show great potential for use in many food, cosmetic, and pharmaceutical formulations.

关键词： Astaxanthin poly (1-lactic acid) Encapsulation Supercritical anti-solvent Stability

Microbial production of natural poly amino acid

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Science China Chemistry 2007年第3期50卷 291-303页

作者： SHI Feng XU ZhiNan CEN PeiLin Institute of Bioengineering Department of Chemical Engineering and BioengineeringZhejiang UniversityHangzhou 310027China Shandong Province Institute of Drug Control Jinan 250012China

Three kinds of poly amino acids, poly-γ-glutamic acid, poly(ε-L-lysine) and multi-L-arginyl-poly (L-aspartic acid) can be synthesized by enzymatic process independently from ribosomal protein biosynthesis pathways in microorganism. These biosynthesized polymers have attracted more and more attentions because of their unique properties and various applications. In this review, the current knowledge on the biosynthesis, biodegradations and applications of these three poly amino acids are summarized.

关键词： poly amino acid biosynthesis metabolism application

Classification of positive solutions to an integral system with the poly-harmonic extension operator

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Science China Mathematics 2018年第9期61卷 1603-1616页

作者： Sufang Tang Jingbo Dou School of Statistics Xi'an University of Finance and Economics School of Mathematics and Information Science Shaanxi Normal University

In this paper, we investigate the positive solutions to the following integral system with a polyharmonic extension operator on R^+_n:{u(x)=c_n,a∫_?R_+~n(x_n^(1-a_v)(y)/|x-y|^(n-a))dy,x∈R_+~n,v(y)=c_n,a∫_R_+~n(x_n^(1-a_uθ)(x)/|x-y|^(n-a))dx,y∈ ?R_+~n,where n 2, 2-n 0. This integral system arises from the Euler-Lagrange equation corresponding to an integral inequality on the upper half space established by Chen(2014). The explicit formulations of positive solutions are obtained by the method of moving spheres for the critical case κ =n-2+a/n-a,θ =n+2-a/ n-2+a. Moreover,we also give the nonexistence of positive solutions in the subcritical case for the above system.

关键词：不可分系统 poly 操作符分类泛音操作员空格

SEMICONDUCTING AND METALLIC polyMERS:THE FOURTH GENERATION OF polyMERIC MATERIALS

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Chinese Journal of polymer Science 2001年第6期19卷 545-572页

作者： AlanJ.Heeger Department of Physics Materials Department Institute for Polymers and Organic Solids University of California Santa Barbara Santa Barbara CA 93106 USA

INTRODUCTIONIn 1976, Alan MacDiarmid, Hideki Shirakawa and I, together with a talented group of graduate students andpost-doctoral researchers discovered conducting polymers and the ability to dope these polymers over the fullrange from insulator to metal. This was particularly exciting because it created a new field of research on theboundary between chemistry and condensed matter physics, and because it created a number of opportunities:

关键词： poly SEMICONDUCTING AND METALLIC polyMERS

Probing the interplay between chain diffusion and polymer crystal growth under nanoscale confinement： a study by single molecule fluorescence microscopy

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Science China Chemistry 2018年第11期61卷 1440-1446页

作者： Xi Lu Kaikai Zheng Jingfa Yang Jiang Zhao Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

Motions of single poly(ε-caprolactone)(PCL) molecules during the formation of the dendrite crystals in ultrathin films are captured by single molecule fluorescence microscopy. The relationship of single molecule diffusion coefficient with the crystal growth rate, together with radius curvature, side-branch spacing of dendrite crystal and morphology are examined. The results support Mullins-Sekerka(MS) instability as the origin of lamellar branching induced by a diffusion field generated by a gradient of polymer segment density ahead of the crystal. Further analysis of the molecular trajectories has recognized different types of motions, depending on the distance to the crystal front: Fickian diffusion in regions far away from the crystal, sub-diffusion in regions adjacent to the crystal, and directed motion between these two regions. Anti-correlation of successive steps is discovered accompanying the sub-diffusion, providing a clear signature of macromolecule crowding at the crystal growth front. This anomalous diffusion process in polymer ultrathin films presents a new insight into the understanding of the retarded dynamics of interfacial mass transport towards the crystal front. It is considered to play a decisive role in controlling the crystal growth and evolution of crystal morphology.

关键词：水晶生长单个分子荧光显微镜聚合物晶体形态学探查控制语言 poly

Aggregation-induced emission and thermally activated delayed fluorescence of 2,6-diaminobenzophenones

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Science China Chemistry 2018年第8期61卷 925-931页

作者： Masaki Shimizu Masaki Nakatani Kenta Nishimura Faculty of Molecular Chemistry and Engineering Kyoto Institute of Technology

Exploration of novel organic luminophores that exhibit thermally activated delayed fluorescence(TADF) in the aggregated state is very crucial for advance of delayed luminescence-based applications such as time-gated bio-sensing and temperature sensing.We report herein that synthesis, photophysical properties, molecular and crystal structures, and theoretical calculations of 2,6-bis(diarylamino)benzophenones. Absorption spectra in solution and calculations using density functional theory(DFT) method revealed that the optical excitation took place through intramolecular charge-transfer from one diarylamino moiety to an aroyl group. While the benzophenones did not luminesce in solution, the solids of the benzophenones emitted green light with moderate-to-good quantum yields. Thus, the benzophenones exhibit aggregation-induced emission. Based on the lifetime measurement, the green emission of the solids was found to include TADF. The emergence of the TADF is supported by the small energy gap between the excited singlet and triplet states, which was estimated by time-dependent DFT calculations. Thin films of poly(methyl methacrylate) doped by the benzophenones also showed green prompt and delayed fluorescence whose lifetimes were in the order of microseconds. Linear correlation between logarithm value of TADF lifetime and temperature was observed with the benzophenone in powder, suggesting that the benzophenones can serve as molecular thermometers workable under aqueous conditions.

关键词：排放聚集荧光激活水晶结构时间依赖温度计 poly

Mechanical Properties of Interlocked-ring polymers: A Molecular Dynamics Simulation Study

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Chinese Journal of polymer Science 2019年第12期37卷 1298-1304,I0008页

作者： Zheng-Tao Wu Jia-Jia Zhou College of Engineering Zhejiang Normal UniversityJinhua 321004China School of Chemistry Beihang UniversityBeijing 100191China

Interlocked-ring polymers,also known as polycatenanes,possess an interesting molecular architecture.These polymers are composed of many interlocked rings in a linear chain.The topological constrain between neighboring rings distinguishes the interlockedring polymer from its linear counterpart.Here we present extensive molecular dynamic simulations on the interlocked-ring polymers and analyze the static properties of the polymer.By applying external forces to the polymer,we also study the force-extension curves of the polymer,which provides rich information about the mechanical properties of the interlockedring polymers.

关键词： poly catenanes Molecular dynamics simulation Force-extension Entanglement

High mobility group box-1 release from H2O2-injured hepatocytes due to sirt1 functional inhibition

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World Journal of Gastroenterology 2019年第36期25卷 5434-5450页

作者： Ting-Jie Ye Yan-Lin Lu Xiao-Feng Yan Xu-Dong Hu Xiao-Ling Wang Department of Biology School of Basic Medical Sciences Shanghai University of Traditional Chinese Medicine Shanghai 201203 China Department of Oncology and Institute of Traditional Chinese Medicine in Oncology Longhua Hospital Shanghai University of Traditional Chinese Medicine Shanghai 200032 China

BACKGROUND High mobility group box-1 (HMGB1), recognized as a representative of damageassociated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting in tissue damage. Dozens of studies have shown that HMGB1 is involved in certain diseases, but the details on how injured hepatocytes release HMGB1 need to be elicited. AIM To reveal HMGB1 release mechanism in hepatocytes undergoing oxidative stress. METHODS C57BL6/J male mice were fed a high-fat diet for 12 wk plus a single binge of ethanol to induce severe steatohepatitis. Hepatocytes treated with H2O2 were used to establish an in vitro model. Serum alanine aminotransferase, liver H2O2 content and catalase activity, lactate dehydrogenase and 8-hydroxy-2- deoxyguanosine content, nicotinamide adenine dinucleotide (NAD+) levels, and Sirtuin 1 (Sirt1) activity were detected by spectrophotometry. HMGB1 release was measured by enzyme linked immunosorbent assay. HMGB1 translocation was observed by immunohistochemistry/immunofluorescence or Western blot. Relative mRNA levels were assayed by qPCR and protein expression was detected by Western blot. Acetylated HMGB1 and poly(ADP-ribose)polymerase 1 (Parp1) were analyzed by Immunoprecipitation. RESULTS When hepatocytes were damaged, HMGB1 translocated from the nucleus to the cytoplasm because of its hyperacetylation and was passively released outside both in vivo and in vitro. After treatment with Sirt1-siRNA or Sirt1 inhibitor (EX527), the hyperacetylated HMGB1 in hepatocytes increased, and Sirt1 activity inhibited by H2O2 could be reversed by Parp1 inhibitor (DIQ). Parp1 and Sirt1 are two NAD+-dependent enzymes which play major roles in the decision of a cell to live or die in the context of stress . We showed that NAD+ depletion attributed to Parp1 activation after DNA damage was caused by oxidative stress in hepatocytes and resulted in Sirt1 activity inhibition. On the contrary, Sirt1 suppressed Parp1 by negatively regulating its gene expression and deace

关键词： Sirtuin1 poly ADP-ribose polymerase 1 High mobility group box-1 Hepatocytes Hydrogen peroxide

Synthesis　and　Characterization　of　the　Side　Chain　Liquid　Crystalline　poly(monoester｛6-[4-(p-nitrophen

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Chemical Research in Chinese Universities 1998年第1期14卷 81-86页

作者： Xing, Pei-xiang Wang, Da-yang Tian, Yan-qing Liu, Zhi-qiang Zhao, Ying-ying Tang, Xin-yi Jiang, Bing-zheng Acad Sinica Changchun Inst Appl Chem Polymer Phys Lab Changchun 130022 Peoples R China Jilin Univ Dept Chem Changchun 130023 Peoples R China

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关键词： poly monoester Crystalline Characterization Liquid Chain