The objective of this work is to analyze the transient effects of ^60Co gamma rays in the CMOS image sensor (CIS) using the Monte Carlo method, based on Geant4. The track, energy spectrum, and angle of produced electr...The objective of this work is to analyze the transient effects of ^60Co gamma rays in the CMOS image sensor (CIS) using the Monte Carlo method, based on Geant4. The track, energy spectrum, and angle of produced electrons when gamma rays traversed a silicon or silicon dioxide cube were calculated. A simplified model of a 500 × 500 CIS array was established, and the transient effects of gamma rays in the CIS were simulated. The raw images were captured when the CIS was irradiated by gamma rays. The experimental results were compared with the simulation results. The characteristics of the typical events induced by transient effects were analyzed.展开更多
According to analysis of the ^14C content in two Japanese trees, that grew over a period of approximately 3000 years, with high time resolution, Miyake et al. found a rapid increase at AD 774-775 and another one at AD...According to analysis of the ^14C content in two Japanese trees, that grew over a period of approximately 3000 years, with high time resolution, Miyake et al. found a rapid increase at AD 774-775 and another one at AD 993-994. These increases correspond to high-energy events that happened within those years and radi- ated ＂）,-ray energy of about 7x 1034 erg toward the Earth. The origin of these events is a mystery. Such strong events should have an unusual optical counterpart, and have been recorded in historical literatures. We searched Chinese historical materi- als around AD 744-775 and AD 993-994, but no remarkable event was found except for a violent thunderstorm in AD 775. However, the possibility of a thunderstorm containing so much energy is unlikely. We conclude that the events, which caused the 14C increase, are still unclear. These events most probably had no optical counterpart, and a short gamma-ray burst, giant flare of a soft gamma-ray repeater or a terrestrial γ-ray flash could all be candidates.展开更多
Colloidal silver nanoparticles (AgNPs) with particle size less than 10 nm and concentration of 2 mM/L (~200 mg/L) were synthesized by gamma Co-60 ray irradiation of Ag+/chitosan solutions with different chitosan conce...Colloidal silver nanoparticles (AgNPs) with particle size less than 10 nm and concentration of 2 mM/L (~200 mg/L) were synthesized by gamma Co-60 ray irradiation of Ag+/chitosan solutions with different chitosan concentration of 0.5%, 1% and 2% (w/v). Incorporation of AgNPs onto cotton fabric was carried out by padding method with 100% wet pick-up. The content of AgNPs deposited on cotton fabric and released from cotton fabric after repeated washing was determined by inductively couple plasma-atomic emission spectroscopy (ICP-AES). The results indicated that cotton/AgNPs fabric made from padding into AgNPs solution with 0.5% - 1% chitosan was the best one of AgNPs adhesion ability on cotton fabric. Results on antibacterial activity against S. aureus showed that cotton/AgNPs fabric with AgNPs content more than 100 mg/kg exhibited highly antibacterial activity (η > 98%). The mechanical property (tensile strength and elongation) of cotton/AgNPs fabrics was almost unchanged in comparison with untreated cotton fabric. Thus, the resultant cotton/AgNPs fabric with highly antibacterial activity can be potentially used as bed drapes and/or patient uniforms in hospitals, etc.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11805155,11875223,and 11690043)the Chinese Academy of Sciences strategic pilot science and technology project(No.XDA15015000)+1 种基金the Innovation Foundation of Radiation Application(No.KFZC2018040201)the Foundation of State Key Laboratory of China(Nos.SKLIPR1803 and 1610)
文摘The objective of this work is to analyze the transient effects of ^60Co gamma rays in the CMOS image sensor (CIS) using the Monte Carlo method, based on Geant4. The track, energy spectrum, and angle of produced electrons when gamma rays traversed a silicon or silicon dioxide cube were calculated. A simplified model of a 500 × 500 CIS array was established, and the transient effects of gamma rays in the CIS were simulated. The raw images were captured when the CIS was irradiated by gamma rays. The experimental results were compared with the simulation results. The characteristics of the typical events induced by transient effects were analyzed.
基金supported by the National Natural Science Foundation of China (Grant No. U1231101)the National Basic Research Program of China (973 Program, Grant No. 2014CB845800)
文摘According to analysis of the ^14C content in two Japanese trees, that grew over a period of approximately 3000 years, with high time resolution, Miyake et al. found a rapid increase at AD 774-775 and another one at AD 993-994. These increases correspond to high-energy events that happened within those years and radi- ated ＂）,-ray energy of about 7x 1034 erg toward the Earth. The origin of these events is a mystery. Such strong events should have an unusual optical counterpart, and have been recorded in historical literatures. We searched Chinese historical materi- als around AD 744-775 and AD 993-994, but no remarkable event was found except for a violent thunderstorm in AD 775. However, the possibility of a thunderstorm containing so much energy is unlikely. We conclude that the events, which caused the 14C increase, are still unclear. These events most probably had no optical counterpart, and a short gamma-ray burst, giant flare of a soft gamma-ray repeater or a terrestrial γ-ray flash could all be candidates.
文摘Colloidal silver nanoparticles (AgNPs) with particle size less than 10 nm and concentration of 2 mM/L (~200 mg/L) were synthesized by gamma Co-60 ray irradiation of Ag+/chitosan solutions with different chitosan concentration of 0.5%, 1% and 2% (w/v). Incorporation of AgNPs onto cotton fabric was carried out by padding method with 100% wet pick-up. The content of AgNPs deposited on cotton fabric and released from cotton fabric after repeated washing was determined by inductively couple plasma-atomic emission spectroscopy (ICP-AES). The results indicated that cotton/AgNPs fabric made from padding into AgNPs solution with 0.5% - 1% chitosan was the best one of AgNPs adhesion ability on cotton fabric. Results on antibacterial activity against S. aureus showed that cotton/AgNPs fabric with AgNPs content more than 100 mg/kg exhibited highly antibacterial activity (η > 98%). The mechanical property (tensile strength and elongation) of cotton/AgNPs fabrics was almost unchanged in comparison with untreated cotton fabric. Thus, the resultant cotton/AgNPs fabric with highly antibacterial activity can be potentially used as bed drapes and/or patient uniforms in hospitals, etc.
