Sichuan University

About: Sichuan University is a education organization based out in Chengdu, China. It is known for research contribution in the topics: Population & Catalysis. The organization has 107623 authors who have published 102844 publications receiving 1612131 citations. The organization is also known as: Sìchuān Dàxué.

Control of Crystal Morphology in Poly(l-lactide) by Adding Nucleating Agent

Abstract: In the past few years, poly(L-lactide) (PLLA) has attracted increasing attention due to its excellent biocompatibility and processability. As an eco-friendly thermoplastic polyester, PLLA can be produced completely from renewable sources, such as corn, and degrade into carbon dioxide and water in soil or a composting environment. This sustainability makes PLLA a suitable alternative to traditional petrochemical-based polymers where their recycling still remains a challenge. PLLA has good mechanical properties at room temperature, such as high tensile strength and elastic modulus, but its article prepared by practical processing methods (e.g., injection molding) exhibits poor mechanical performance above its glass transition temperature (around 60 C) since it remains almost amorphous after processing due to its slow crystallization rate.Moreover, PLLA is brittle and its long-term behavior is poor because of a pronounced creep. The crystallization can restrict molecular mobility and then improve the long-term performance. Obviously, PLLA article with suitable crystallinity is required in many commercial applications. On the other hand, the mechanical, thermal properties, and even biodegradability of such semicrystalline polymer have been demonstrated to be strongly dependent on the crystal morphology and structure. Therefore, the realization of effective control on the crystal superstructure consisting of crystalline lamella, such as spherulites and shish-kebab structure, is of great scientific and technical significance because it might provide a route to prepare PLLA products with excellent macroscopic performance. In most cases, isotropic spherulite-like crystal morphology is observed for semicrystalline polymer including PLLA, while shish-like fibril crystals are often obtained from the sheared melt. Many researchers reported that adding nucleating agent is a useful method for controlling the crystal superstructure of polymer, such as polyolefins. For example, the exclusive formation of bundle-like superstructure for β-phase and the radiating, spherulitic superstructure for R-phase in polypropylene (PP) can be induced by adding highly active β-form and R-form nucleating agent, respectively. Moreover, the assembled structure could vary with its concentration and the thermal conditions during melting and crystallization if the nucleating agent is partially or completely dissolved in the polymer melt and recrystallize during cooling. As a result, different superstructures of PP could be induced. For instance, sorbitol-based nucleating agents, such as well-known 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (DMDBS), can self-organize into nanofibils on cooling, and then lateral growth of PP lamellae occurs orthogonally to the fibrils, forming a typical shish-kebab structure. Thus, adding nucleating agent with the ability of self-organizing in polymer melt is believed to be an important method to manipulate crystal morphology as well as properties of polymer articles. Similar to DMDBS, 1,3,5-benzenetricarboxylamide derivatives, another family of nucleating agents for PP, are also found to be capable of self-organizing in PPmelt through intermolecular hydrogen bonding of the amides in the form of a three-dimensional fibrillar network. Very recently, the derivatives have been successfully used to enhance the crystallization of PLLA. However, no attention has been paid to the self-organization of the derivatives in PLLA melt and its subsequent effect on the crystal morphology of PLLA though it is very important for the macroscopic performance. Therefore, in this Communication, we use one of the above derivatives, i.e., N,N0,N00-tricyclohexyl-1,3,5-benzenetricarboxylamide (TMC-328), as a model to tailor the crystal superstructure of PLLA, and three crystal morphologies including cone-like, shish-kebab, and needle-like structures have been successfully obtained for the first time using melt crystallization. Furthermore, the evolution of crystal morphology during crystallization is investigated using in-situ POM and rheological measurement.

Randomized trials published in some Chinese journals: how many are randomized?

Abstract: The approximately 1100 medical journals now active in China are publishing a rapidly increasing number of research reports, including many studies identified by their authors as randomized controlled trials. It has been noticed that these reports mostly present positive results, and their quality and authenticity have consequently been called into question. We investigated the adequacy of randomization of clinical trials published in recent years in China to determine how many of them met acceptable standards for allocating participants to treatment groups. The China National Knowledge Infrastructure electronic database was searched for reports of randomized controlled trials on 20 common diseases published from January 1994 to June 2005. From this sample, a subset of trials that appeared to have used randomization methods was selected. Twenty-one investigators trained in the relevant knowledge, communication skills and quality control issues interviewed the original authors of these trials about the participant randomization methods and related quality-control features of their trials. From an initial sample of 37,313 articles identified in the China National Knowledge Infrastructure database, we found 3137 apparent randomized controlled trials. Of these, 1452 were studies of conventional medicine (published in 411 journals) and 1685 were studies of traditional Chinese medicine (published in 352 journals). Interviews with the authors of 2235 of these reports revealed that only 207 studies adhered to accepted methodology for randomization and could on those grounds be deemed authentic randomized controlled trials (6.8%, 95% confidence interval 5.9–7.7). There was no statistically significant difference in the rate of authenticity between randomized controlled trials of traditional interventions and those of conventional interventions. Randomized controlled trials conducted at hospitals affiliated to medical universities were more likely to be authentic than trials conducted at level 3 and level 2 hospitals (relative risk 1.58, 95% confidence interval 1.18–2.13, and relative risk 14.42, 95% confidence interval 9.40–22.10, respectively). The likelihood of authenticity was higher in level 3 hospitals than in level 2 hospitals (relative risk 9.32, 95% confidence interval 5.83–14.89). All randomized controlled trials of pre-market drug clinical trial were authentic by our criteria. Of the trials conducted at university-affiliated hospitals, 56.3% were authentic (95% confidence interval 32.0–81.0). Most reports of randomized controlled trials published in some Chinese journals lacked an adequate description of randomization. Similarly, most so called 'randomized controlled trials' were not real randomized controlled trials owing toa lack of adequate understanding on the part of the authors of rigorous clinical trial design. All randomized controlled trials of pre-market drug clinical trial included in this research were authentic. Randomized controlled trials conducted by authors in high level hospitals, especially in hospitals affiliated to medical universities had a higher rate of authenticity. That so many non-randomized controlled trials were published as randomized controlled trials reflected the fact that peer review needs to be improved and a good practice guide for peer review including how to identify the authenticity of the study urgently needs to be developed.

Fabrication of hierarchical CoP nanosheet@microwire arrays via space-confined phosphidation toward high-efficiency water oxidation electrocatalysis under alkaline conditions

Abstract: In spite of recent advances in the synthesis of transition metal phosphide nanostructures, the simple fabrication of hierarchical arrays with more accessible active sites still remains a great challenge. In this Communication, we report a space-confined phosphidation strategy toward developing hierarchical CoP nanosheet@microwire arrays on nickel foam (CoP NS@MW/NF) using a Co(H2PO4)2·2H3PO4 microwire array as the precursor. The thermally stable nature of the anion in the precursor is key to hierarchical nanostructure formation. When used as a 3D electrode for water oxidation electrocatalysis, such CoP NS@MW/NF needs an overpotential as low as 296 mV to drive a geometrical catalytic current density of 100 mA cm−2 in 1.0 M KOH, outperforming all reported Co phosphide catalysts in alkaline media. This catalyst also shows superior long-term electrochemical durability, maintaining its activity for at least 65 h. This study offers us a general method for facile preparation of hierarchical arrays for applications.

Inhibition of BET bromodomains as a therapeutic strategy for cancer drug discovery.

Abstract: // Lei-lei Fu 1,* , Mao Tian 1,* , Xiang Li 1,* , Jing-jing Li 1 , Jian Huang 2 , Liang Ouyang 1 , Yonghui Zhang 1,3 and Bo Liu 1 1 State Key Laboratory of Biotherapy, Collaborative Innovation Center of Biotherapy, Department of Urology, West China Hospital, Sichuan University, Chengdu, China 2 School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, China 3 Collaborative Innovation Center for Biotherapy, Department of Pharmacology & Pharmaceutical Sciences, School of Medicine, Tsinghua University, Beijing, China * These authors contributed equally to this work Correspondence to: Bo Liu, email: // Jian Huang, email: // Keywords : bromodomain, BRD2/4, BRD3, BRDT, BET inhibitor Received : January 22, 2015 Accepted : February 13, 2015 Published : March 12, 2015 Abstract As a conserved protein interaction module that recognizes and binds to acetylated lysine, bromodomain (BRD) contains a deep, largely hydrophobic acetyl lysine binding site. Proteins that share the feature of containing two BRDs and an extra-terminal domain belong to BET family, including BRD2, BRD3, BRD4 and BRDT. BET family proteins perform transcription regulatory function under normal conditions, while in cancer, they regulate transcription of several oncogenes, such as c-Myc and Bcl-2. Thus, targeting BET proteins may be a promising strategy, and intense interest of BET proteins has fueled the development of structure-based bromodomain inhibitors in cancer. In this review, we focus on summarizing several small-molecule BET inhibitors and their relevant anti-tumor mechanisms, which would provide a clue for exploiting new targeted BET inhibitors in the future cancer therapy.

An ice-templated assembly strategy to construct graphene oxide/boron nitride hybrid porous scaffolds in phase change materials with enhanced thermal conductivity and shape stability for light–thermal–electric energy conversion

Abstract: Latent heat energy storage and release media of organic phase change materials (PCMs) are promising to utilize thermal energy coming from solar radiation for effective thermal management. However, the inherently low thermal conductivity and poor photoabsorption of organic PCMs lead to slow thermal charging/discharging rates, hindering the direct thermal energy conversion and storage. Here, we demonstrate that multifunctional PCMs with high thermal conductivity, improved shape-stability and efficient light–thermal–electric energy conversion can be fabricated by introducing polyethylene glycol (PEG) into graphene oxide (GO)/boron nitride (BN) hybrid porous scaffolds (HPSs) constructed via an ice-templated assembly strategy. Owing to the self-assembly of thermally conductive fillers during ice-growth, the obtained PCMs exhibit a high thermal conductivity (as high as 1.84 W m−1 K−1 at 19.2 wt% of BN), which is much higher than that of the composites fabricated by the solution blending method. Furthermore, the obtained composite PCMs with high energy storage density and excellent thermal stability can also be utilized to realize efficient light-to-thermal and light-to-electric energy conversion and storage, providing promising application potential in advanced energy-related devices and systems for solar energy utilization and storage.