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.

Water-induced shape memory effect of graphene oxide reinforced polyvinyl alcohol nanocomposites

Abstract: A novel water-induced shape memory polymer based on polyvinyl alcohol (PVA) was prepared by introducing graphene oxide (GO). Due to the strong hydrogen bonding interaction between PVA and GO, some additional physically cross-linked points could be formed in PVA, which largely improved shape memory properties of PVA. Solvent-induced shape memory behavior was observed by immersing PVA/GO nanocomposites in water. The water-induced shape recovery was due to the decrease of glass transition temperature and storage modulus. This could be explained by the swelling plasticizing effect of water on PVA, as indicated by the obvious expansion in volume of PVA. On the other hand, the weakened hydrogen bonding between PVA and GO was also observed after immersing the PVA/GO nanocomposites in water. Thus both the plasticizing effect and the competitive hydrogen bonding were the two main reasons for the shape recovery of PVA/GO nanocomposites. This study provides a framework for developing new shape memory polymers (SMPs) and for better understanding the shape recovery mechanism in solvent-induced SMPs.

Boron delivery agents for neutron capture therapy of cancer

Abstract: Boron neutron capture therapy (BNCT) is a binary radiotherapeutic modality based on the nuclear capture and fission reactions that occur when the stable isotope, boron-10, is irradiated with neutrons to produce high energy alpha particles. This review will focus on tumor-targeting boron delivery agents that are an essential component of this binary system. Two low molecular weight boron-containing drugs currently are being used clinically, boronophenylalanine (BPA) and sodium borocaptate (BSH). Although they are far from being ideal, their therapeutic efficacy has been demonstrated in patients with high grade gliomas, recurrent tumors of the head and neck region, and a much smaller number with cutaneous and extra-cutaneous melanomas. Because of their limitations, great effort has been expended over the past 40 years to develop new boron delivery agents that have more favorable biodistribution and uptake for clinical use. These include boron-containing porphyrins, amino acids, polyamines, nucleosides, peptides, monoclonal antibodies, liposomes, nanoparticles of various types, boron cluster compounds and co-polymers. Currently, however, none of these have reached the stage where there is enough convincing data to warrant clinical biodistribution studies. Therefore, at present the best way to further improve the clinical efficacy of BNCT would be to optimize the dosing paradigms and delivery of BPA and BSH, either alone or in combination, with the hope that future research will identify new and better boron delivery agents for clinical use.

Preliminary prediction of the basic reproduction number of the Wuhan novel coronavirus 2019-nCoV.

Abstract: Objectives To estimate the basic reproduction number of the Wuhan novel coronavirus (2019-nCoV). Methods Based on the susceptible-exposed-infected-removed (SEIR) compartment model and the assumption that the infectious cases with symptoms occurred before 26 January, 2020 are resulted from free propagation without intervention, we estimate the basic reproduction number of 2019-nCoV according to the reported confirmed cases and suspected cases, as well as the theoretical estimated number of infected cases by other research teams, together with some epidemiological determinants learned from the severe acute respiratory syndrome (SARS). Results The basic reproduction number fall between 2.8 and 3.3 by using the real-time reports on the number of 2019-nCoV-infected cases from People's Daily in China and fall between 3.2 and 3.9 on the basis of the predicted number of infected cases from international colleagues. Conclusions The early transmission ability of 2019-nCoV is close to or slightly higher than SARS. It is a controllable disease with moderate to high transmissibility. Timely and effective control measures are needed to prevent the further transmissions.

RASP 4: ancestral state reconstruction tool for multiple genes and characters

Abstract: With the continual progress of sequencing techniques, genome-scale data are increasingly used in phylogenetic studies. With more data from throughout the genome, the relationship between genes and different kinds of characters is receiving more attention. Here, we present version 4 of RASP, a software to reconstruct ancestral states through phylogenetic trees. RASP can apply generalized statistical ancestral reconstruction methods to phylogenies, explore the phylogenetic signal of characters to particular trees, calculate distances between trees, and cluster trees into groups. RASP 4 has an improved graphic user interface and is freely available from http://mnh.scu.edu.cn/soft/blog/RASP (program) and https://github.com/sculab/RASP (source code).

T2* and FSE MRI distinguishes four subtypes of neurodegeneration with brain iron accumulation

Abstract: Iron accumulates within the basal ganglia and dentate nuclei during normal aging.1 More intense iron deposition has been demonstrated within the substantia nigra in Parkinson disease, and structures affected by β amyloid plaques in Alzheimer disease, implicating iron deposition in the pathogenesis of common neurodegenerative diseases, possibly through increased oxidative stress.2,3 Direct evidence supporting a causal role for iron deposition in neurodegenerative conditions comes from a group of genetic disorders termed neurodegeneration with brain iron accumulation (NBIA), in which a variety of genetic defects in iron metabolism lead to brain iron accumulation with neuronal death in the affected brain regions.4 Four subtypes of NBIA have been defined at the molecular genetic level. Pantothenate kinase associated neurodegeneration (PKAN, NBIA type one, MIM 234200), formerly known as Hallervorden-Spatz syndrome, is caused by mutation of the pantothenate kinase 2 gene (PANK2).5 Infantile neuroaxonal dystrophy (INAD, MIM 256600) is a recessive disorder with psychomotor regression due to mutations in PLA2G6.6 Mutations of the ferritin light chain gene (FTL1) cause the adult onset autosomal dominant movement disorder neuroferritinopathy (FTL, NBIA type two, hereditary ferritinopathy, MIM 606159).7 A further form of NBIA is aceruloplasminemia (aCp, MIM 604290), an autosomal recessive ceruloplasmin deficiency which results in iron deposition in the reticuloendothelial system and brain, presenting with diabetes and an extrapyramidal movement disorder in adult life.8 Extensive phenotypic overlap presents a major challenge in the clinical diagnosis of different subtypes of NBIA, particularly in the early stages. Although molecular genetic testing can provide the definitive diagnosis, comprehensive testing is only available on a research basis, and the genetic defect remains undefined in a large subgroup of patients with so-called NBIA of unknown cause. A reliable clinical investigation capable of predicting the genetic diagnosis would be useful to inform genetic counseling, predict the disease course, and ensure appropriate enrollment in clinical trials of new treatments. Dramatic evidence of focal brain iron accumulation on brain imaging is usually the first indication of NBIA, but the features distinguishing the different subtypes have yet to be defined.