A GEANT4-based Monte-Carlo （MC） model is developed to study the performance of endcap time- of-flight （ETOF） at BESIII. It＇s found that the multiple scattering effects, mainly from the materials at the MDC endcap...A GEANT4-based Monte-Carlo （MC） model is developed to study the performance of endcap time- of-flight （ETOF） at BESIII. It＇s found that the multiple scattering effects, mainly from the materials at the MDC endcap, can cause multi-hit on the ETOF＇s readout cell and significantly influence the timing property of ETOF. A multi-gap resistive plate chamber （MRPC） with a smaller readout cell structure is more suitable for the ETOF detector due to significantly reduced multi-hit rate （per channel）, from 71.5% for currently-used scintillator-based ETOF to 21.8% or 16.7% for MRPC-based ETOF, depending on the readout pad size used. The timing performance of an MRPC ETOF is also improved. These simulation results suggest and guide an ETOF upgrade effort at BESIII.展开更多
Ceramics constitute an integral part of highly efficient armours due to their low density, high hardness, strength and stiffness. However, they lack toughness and multi-hit capability. Therefore, zirconia toughened al...Ceramics constitute an integral part of highly efficient armours due to their low density, high hardness, strength and stiffness. However, they lack toughness and multi-hit capability. Therefore, zirconia toughened alumina is investigated. The hardness is evaluated using Vickers, Knoop and instrumented indentations, while the fracture toughness is evaluated using the indentation technique and Charpy tests. The strength is evaluated using ring-on-ring, four point bend and drop weight tests. The Young’s modulus is evaluated using the unloading instrumented indentation curves. Microstructure, porosity and density are characterised using ultrasonic scanning, Archimedes principle, optical and scanning electron microscopy. Results show an indentation size effect on all mechanical properties. A substantial improvement in toughness is achieved through retardation of crack initiation by tetragonal-to-monoclinic phase transformation in zirconia particles, crack deviation thanks to appropriate grain structure, as well as energy absorption by densification due to remaining porosity. This improved toughness is expected to promote multi-hit capability.展开更多
The high therapeutic resistance of tumor is the primary cause behind tumor recurrence and incurability.In recent years,scientists have devoted themselves to find a variety of treatments to solve this problem.Herein,we...The high therapeutic resistance of tumor is the primary cause behind tumor recurrence and incurability.In recent years,scientists have devoted themselves to find a variety of treatments to solve this problem.Herein,we propose a multi-hit strategy that is based on the biodegradable hollow mesoporous Prussian blue(HMPB)-based nanosystem for tumor-specific therapy that encapsulated the critical heat shock protein 90(HSP90)inhibitor 17-dimethylamino-ethylamino-17-demethoxydeldanamycin(17-DMAG).The nanosystem was further modified using thermotropic phase transition material star-PEG-PCL(sPP)and hyaluronic acid(HA),which offers near infrared light(NIR)responsive release characteristic,as well as enhanced tumor cell endocytosis.Upon cell internalization of 17-DMAG-HMPB@sPP@HA and under 808 nm laser irradiation,photothermal-conversion effect of HMPB directly kills cells using hyperthermia,which further causes phase transition of sPP to trigger release of 17-DMAG,inhibits HSP90 activity and blocks multiple signaling pathways,including cell cycle,Akt and HIF pathways.Additionally,the down-regulation of GPX4 protein expression by 17-DMAG and the release of ferric and ferrous ions from gradual degradation of HMPB in the endogenous mild acidic microenvironment in tumors promoted the occurrence of ferroptosis.Importantly,the antitumor effect of 17-DMAG and ferroptosis damage were amplified using photothermal effect of HMPB by accelerating release of ferric and ferrous ions,and reducing HSP90 expression in cells,which induced powerful antitumor effect in vitro and in vivo.This multi-hit therapeutic nanosystem helps provide a novel perspective for solving the predicament of cancer treatment,as well as a promising strategy for design of a novel cancer treatment nanoplatform.展开更多
基金Supported by National Natural Science Foundation of China(10979003)
文摘A GEANT4-based Monte-Carlo （MC） model is developed to study the performance of endcap time- of-flight （ETOF） at BESIII. It＇s found that the multiple scattering effects, mainly from the materials at the MDC endcap, can cause multi-hit on the ETOF＇s readout cell and significantly influence the timing property of ETOF. A multi-gap resistive plate chamber （MRPC） with a smaller readout cell structure is more suitable for the ETOF detector due to significantly reduced multi-hit rate （per channel）, from 71.5% for currently-used scintillator-based ETOF to 21.8% or 16.7% for MRPC-based ETOF, depending on the readout pad size used. The timing performance of an MRPC ETOF is also improved. These simulation results suggest and guide an ETOF upgrade effort at BESIII.
文摘Ceramics constitute an integral part of highly efficient armours due to their low density, high hardness, strength and stiffness. However, they lack toughness and multi-hit capability. Therefore, zirconia toughened alumina is investigated. The hardness is evaluated using Vickers, Knoop and instrumented indentations, while the fracture toughness is evaluated using the indentation technique and Charpy tests. The strength is evaluated using ring-on-ring, four point bend and drop weight tests. The Young’s modulus is evaluated using the unloading instrumented indentation curves. Microstructure, porosity and density are characterised using ultrasonic scanning, Archimedes principle, optical and scanning electron microscopy. Results show an indentation size effect on all mechanical properties. A substantial improvement in toughness is achieved through retardation of crack initiation by tetragonal-to-monoclinic phase transformation in zirconia particles, crack deviation thanks to appropriate grain structure, as well as energy absorption by densification due to remaining porosity. This improved toughness is expected to promote multi-hit capability.
基金This work was supported by:National Natural Science Foundation of China(Grant No:81503020)Natural Science Foundation of Liaoning Province(Grant No:2019-ZD-0459,2020-MS-196)and the Basic Research Project of Liaoning Provincial Department of Education(Grant No:2019LJC04).
文摘The high therapeutic resistance of tumor is the primary cause behind tumor recurrence and incurability.In recent years,scientists have devoted themselves to find a variety of treatments to solve this problem.Herein,we propose a multi-hit strategy that is based on the biodegradable hollow mesoporous Prussian blue(HMPB)-based nanosystem for tumor-specific therapy that encapsulated the critical heat shock protein 90(HSP90)inhibitor 17-dimethylamino-ethylamino-17-demethoxydeldanamycin(17-DMAG).The nanosystem was further modified using thermotropic phase transition material star-PEG-PCL(sPP)and hyaluronic acid(HA),which offers near infrared light(NIR)responsive release characteristic,as well as enhanced tumor cell endocytosis.Upon cell internalization of 17-DMAG-HMPB@sPP@HA and under 808 nm laser irradiation,photothermal-conversion effect of HMPB directly kills cells using hyperthermia,which further causes phase transition of sPP to trigger release of 17-DMAG,inhibits HSP90 activity and blocks multiple signaling pathways,including cell cycle,Akt and HIF pathways.Additionally,the down-regulation of GPX4 protein expression by 17-DMAG and the release of ferric and ferrous ions from gradual degradation of HMPB in the endogenous mild acidic microenvironment in tumors promoted the occurrence of ferroptosis.Importantly,the antitumor effect of 17-DMAG and ferroptosis damage were amplified using photothermal effect of HMPB by accelerating release of ferric and ferrous ions,and reducing HSP90 expression in cells,which induced powerful antitumor effect in vitro and in vivo.This multi-hit therapeutic nanosystem helps provide a novel perspective for solving the predicament of cancer treatment,as well as a promising strategy for design of a novel cancer treatment nanoplatform.
