Sun Yat-sen University

About: Sun Yat-sen University is a education organization based out in Guangzhou, Guangdong, China. It is known for research contribution in the topics: Population & Cancer. The organization has 115149 authors who have published 113763 publications receiving 2286465 citations. The organization is also known as: Zhongshan University & SYSU.

Palaeovegetation of China: a pollen data‐based synthesis for the mid‐Holocene and last glacial maximum

Abstract: Pollen data from China for 6000 and 18,000 C-14 yr BP Were compiled and used to reconstruct palaeovegetation patterns, using complete taxon lists where possible and a biomization procedure that entailed the assignment of 645 pollen taxa to plant functional types. A set of 658 modern pollen samples spanning all biomes and regions provided a comprehensive test for this procedure and showed convincing agreement between reconstructed biomes and present natural vegetation types, both geographically and in terms of the elevation gradients in mountain regions of north-eastern and south-western China. The 6000 C-14 yr BP map confirms earlier studies in showing that the forest biomes in eastern China were systematically shifted northwards and extended westwards during the mid-Holocene. Tropical rain forest occurred on mainland China at sites characterized today by either tropical seasonal or broadleaved evergreen/warm mixed forest. Broadleaved evergreen/warm mixed forest occurred further north than today, and at higher elevation sites within the modern latitudinal range of this biome. The northern limit of temperate deciduous forest was shifted c. 800 km north relative to today. The 18,000 C-14 yr BP map shows that steppe and even desert vegetation extended to the modem coast of eastern China at the last glacial maximum, replacing today's temperate deciduous forest. Tropical forests were excluded from China and broadleaved evergreen/warm mixed forest had retreated to tropical latitudes, while taiga extended southwards to c. 43 degreesN.

Core@Shell CsPbBr3@Zeolitic Imidazolate Framework Nanocomposite for Efficient Photocatalytic CO2 Reduction

Abstract: The proper energy band structure and excellent visible-light responses enable halide perovskites as potential photocatalysts for CO2 reduction, but the conversion efficiency is still low due to the serious radiative recombination, low CO2 capturing ability, and poor stability. Here we illustrate the design and synthesis of a halide perovskite@metal–organic framework (MOF) composite photocatalyst with enhanced CO2 reduction activity. A facile in situ synthetic procedure is employed to directly grow a zinc/cobalt-based zeolitic imidazolate framework (ZIF) coating on the surface of CsPbBr3 quantum dots. The CsPbBr3@ZIF composite shows largely improved moisture stability, CO2 capturing ability, and charge separation efficiency. Moreover, the catalytic active Co centers in ZIF-67 can further accelerate the charge separation process and activate the adsorbed CO2 molecules, which leads to enhanced catalytic activity for gaseous CO2 reduction. This work would provide new insight for designing excellent perovskite...

Performance of $b$-Jet Identification in the ATLAS Experiment

Abstract: The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty.

Interlayer-Crosslinked Micelle with Partially Hydrated Core Showing Reduction and pH Dual Sensitivity for Pinpointed Intracellular Drug Release

Abstract: Although the utilization of polymeric micelles has demonstrated great potential in delivering anticancer drugs, this technique is facing tremendous challenges. In particular, polymeric micelles usually show a drug-release profile that is not in favor of achieving optimal drug availability inside tumor cells. That is, a “burst release” of up to 20–30 % of the encapsulated drug within several hours post micelle formation, followed by a slow diffusional drug release lasting for many days. The premature burst release leads to drug loss in micelle storage and blood circulation. Meanwhile, the secondstage slow drug release results in low intracellular drug availability insufficient for killing cancer cells. Therefore, development of delivery systems with better drug-release properties is still of great importance. One of the most promising strategies is to construct polymeric micelles that respond to specific stimulation, such as light exposure, enzymatic degradation, redox reaction, or change in pH or temperature. Acid-triggered rapid release of drugs can be achieved inside tumor tissue (pH below 6.8) or lysosomal compartments (pH about 5.0) of cancer cells by using micelles of copolymers bearing pH-sensitive blocks, such as poly(lhistidine) and poly(b-amino ester). Nevertheless, these pH-sensitive micelles were not designed to avoid the premature burst release of drugs. In addition, supramolecular nanoassemblies de-micellize when the polymer concentration drops below the critical micelle concentration (CMC), which is another underlying cause for the loss of drugs during blood circulation. Recently, covalent crosslinking of the core or shell of selfassembled polymeric micelles has emerged as a viable strategy to prevent de-micellization-associated drug loss. 11] Among various approaches, the utilization of disulfide-containing reversible crosslinkers is of particular importance, owing to the fact that the disulfide bond is reducible and therefore can be cleaved by glutathione (GSH), a thiol-containing oligopeptide predominantly found inside cells (up to the millimolar scale). Indeed, shell-crosslinked micelles (SCMs) obtained using disulfide-containing agents have demonstrated great potential for specifically releasing the loaded cargos inside cells. 13] In spite of their potential in reducing premature drug leakage, these SCMs cannot rapidly release drugs inside cells because drug release from their nonsensitive cores still follows a diffusion-controlled mechanism. Herein, we describe the first example of a highly packed interlayer-crosslinked micelle (HP-ICM) with reduction and pH dual sensitivity, which comprises a polyethylene glycol (PEG) corona to stabilize the particles, a highly compressed pH-sensitive partially hydrated core to load anticancer drugs, and a disulfide-crosslinked interlayer to tie up the core against expansion at neutral pH. The HP-ICM was stable and drug leakage free in a neutral pH environment without reducing agent. However, when the HP-ICM was internalized into cells and trapped inside lysosomes featuring low pH ( 5) and enriched reducing agent (GSH), the pH-sensitive core was unpacked and thus erupted to burst release the anticancer drug (Figure 1). The reductionand pH-sensitive interlayer-crosslinked micelle with partially hydrated core was prepared from a triblock copolymer of monomethoxy polyethylene glycol (mPEG), 2-mercaptoethylamine (MEA)-grafted poly(laspartic acid) (PAsp(MEA)), and 2-(diisopropylamino)ethylamine (DIP)-grafted poly(l-aspartic acid) (PAsp(DIP)). The copolymer was synthesized by ring-opening polymerization of b-benzyl l-aspartate N-carboxy-anhydride (BLA-NCA) in combination with click and aminolysis reactions (see the Supporting Information, Figure S1). So far, most reported shell-crosslinked nanoparticles have been based on polyacrylate or polyacrylamide. 14] We chose biodegradable polypeptide as the copolymer backbone in consideration of biocompatibility requirements in drug delivery. Poly(BLA) aminolysis with MEA and DIP introduced the crosslinkable thiol and pH-sensitive tertiary amino groups onto the middle and end blocks of the copolymer, respectively. NMR and FTIR analyses confirmed the chemical structures of the polymers (see the Supporting Information, Figures S3–S6). Gel permeation chromatography measurements also evidenced the successful synthesis of mPEG[*] Dr. J. Dai, S. Lin, Dr. D. Cheng, Prof. X. Shuai PCFM Lab of Ministry of Education, School of Chemistry and Chemical Engineering Sun Yat-sen University, Guangzhou 510275 (China) E-mail: shuaixt@mail.sysu.edu.cn