分类: 管理学 >> 管理学其他学科 提交时间: 2022-11-24 合作期刊: 《2022年第三届传播、创新和经济管理国际研讨会》
摘要: China has large population, with the development of social and economic, the number of medical waste is growing rapidly. The medical waste is highly infectious and hazardous, that requires us to pay more attention to its proper treatment. China's legal mechanism for medical waste started late, the existing main laws and regulations is Law of the People's Republic of China on the Prevention and Control of Environmental Pollution by Solid Waste and Regulations on the Administration of Medical Wastes. These have made some achievements in the management of medical waste in China and brought the medical waste industry into the track of legal management. But we have to admit that environmental pollution, social security and other problems caused by medical waste occur frequently, and the treatment of medical waste is particularly important. In order to effectively promote the improvement of this problem, in line with the requirements of the 19th National Congress of the CPC on ecological protection, it is necessary to start from the construction of the legal system, drawing on foreign experience in the legal system of medical waste, combining with the actual situation in China, establishing an effective legal system, so as to achieve effective prevent environmental pollution and promote the sustainable development of society.
分类: 物理学 >> 核物理学 提交时间: 2023-05-30
摘要: Thorium-229 possesses the lowest first nuclear excited state, with an energy of approximately 8 eV. The extremely narrow linewidth of the first nuclear excited state, with an uncertainty of 53 THz, prevents direct laser excitation and realization of the nuclear clock. We present a proposal using the Coulomb crystal of a linear chain formed by 229Th3+ ions, where the nuclei of 229Th3+ ions in the ion trap are excited by the electronic bridge (EB) process. The 7 P1∕2 state of the thorium-229 nuclear ground state is chosen for EB excitation. Using the two-level optical Bloch equation under experimental conditions, we calculate that 2 out of 36 prepared thorium ions in the Coulomb crystal can be excited to the first nuclear excited state, and it takes approximately 2h to scan over an uncertainty of 0.22 eV. Taking advantage of the transition enhancement of EB and the long stability of the Coulomb crystal, the energy uncertainty of the first excited state can be limited to the order of 1 GHz
分类: 生物学 >> 生物化学 提交时间: 2017-05-19
摘要: Thirteen new pentacyclic triterpenoids, cleistocalyxic acids AK (1, 2, 4, 5, and 713) and cleistocalyxolides A (3) and B (6), and fifteen known analogues (1428), based on taraxastane, oleanane, ursane, multiflorane, and lupane skeletons, were isolated from the leaves of Cleistocalyx operculatus. The structures of 113 were elucidated by analysis of their spectroscopic data and ECD/TDDFT computations. Cleistocalyxolide A (3), presumed to be derived from the known taraxastane-type compound 14, has a rare rearranged triterpenoid backbone. Cleistocalyxic acid B (2) displayed cytotoxicity against HepG2, NCI-N87, and MCF-7 cancer cell lines with IC50 values ranging from 3.2 to 6.5 M and cleistocalyxic acid D (5) was active against HepG2 and NCI-N87 cells with the values around 5.0 M. The non-cytotoxic cleistocalyxic acid E (7) inhibited production of IL-6 by 68.1% and TNF- by 53.7% in LPS-induced RAW 264.7 macrophages at the concentration of 2 M.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A simulation approach is developed to obtain the linear energy transfer (LET) spectrum of all secondary ions and predict single event upset (SEU) occurrence induced by neutron in memory devices. Neutron reaction channels, secondary ion species and energy ranges, and LET calculation method are introduced respectively. Experimental results of neutron induced SEU effects on static random access memory (SRAM) and programmable read only memory (EEPROM) are presented to confirm the validity of the simulation results.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The Earth occultation technique has broad applications in both astronomy and atmospheric density measurements. We construct the background model during the occultation of the Crab Nebula observed by the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) at energies between 6 keV and 100 keV. We propose a Bayesian atmospheric density retrieval method based on the Earth occultation technique, combining Poisson and Gaussian statistics. By modeling the atmospheric attenuation of X-ray photons during the occultation, we simultaneously retrieved the neutral densities of the atmosphere at different altitude ranges. Our method considers the correlation of densities between neighboring atmospheric layers and reduces the potential systematic bias to which previous work may be subject. Previous analyses based on light curve fitting or spectral fitting also lost some spectral or temporal information of the data. In contrast to previous work, the occultation data observed by the three telescopes onboard Insight-HXMT is fully used in our analysis, further reducing the statistical error in density retrieval. We apply our method to cross-check the (semi-)empirical atmospheric models, using 115 sets of occultation data of the Crab Nebula observed by Insight-HXMT. We find that the retrieved neutral density is ~10%, ~20%, and ~25% less than the values of the widely used atmospheric model NRLMSISE-00, in the altitude range of 55--80 km, 80--90 km, and 90--100 km, respectively. We also show that the newly released atmospheric model NRLMSIS 2.0 is generally consistent with our density measurements.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The gamma-ray detectors (GRDs) of GECAM-C onborad SATech-01 satellite is designed to monitor gamma-ray transients all over the sky from 6 keV to 6 MeV. The energy response matrix is the key to do spectral measurements of bursts, which is usually generated from GEANT4 simulation and partially verified by the ground calibration. In this work, energy response matrix of GECAM-C GRD is cross-calibrated with Fermi/GBM and Swift/BAT using a sample of Gamma-Ray Bursts (GRBs) and Soft Gamma-Ray Repeaters (SGRs). The calibration results show there is a good agreement between GECAM-C and other reasonably well calibrated instrument (i.e. Fermi/GBM and Swift/BAT). We also find that different GRD detectors of GECAM-C also show consistency with each other. All these results indicate that GECAM-C GRD can provide reliable spectral measurements.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a pair of microsatellites (i.e. GECAM-A and GECAM-B) dedicated to monitoring gamma-ray transients including gravitational waves high-energy electromagnetic counterparts, Gamma-ray Bursts, Soft Gamma-ray Repeaters, Solar Flares and Terrestrial Gamma-ray Flashes. Since launch in December 2020, GECAM-B has detected hundreds of astronomical and terrestrial events. For these bursts, localization is the key for burst identification and classification as well as follow-up observations in multi-wavelength. Here, we propose a Bayesian localization method with Poisson data with Gaussian background profile likelihood to localize GECAM bursts based on the burst counts distribution in detectors with different orientations. We demonstrate that this method can work well for all kinds of bursts, especially for extremely short ones. In addition, we propose a new method to estimate the systematic error of localization based on a confidence level test, which can overcome some problems of the existing method in literature. We validate this method by Monte Carlo simulations, and then apply it to a burst sample with accurate location and find that the mean value of the systematic error of GECAM-B localization is $\sim 2.5^{\circ}$. By considering this systematic error, we can obtain a reliable localization probability map for GECAM bursts. Our methods can be applied to other gamma-ray monitors.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a pair of microsatellites (i.e. GECAM-A and GECAM-B) dedicated to monitoring gamma-ray transients including gravitational waves high-energy electromagnetic counterparts, Gamma-ray Bursts, Soft Gamma-ray Repeaters, Solar Flares and Terrestrial Gamma-ray Flashes. Since launch in December 2020, GECAM-B has detected hundreds of astronomical and terrestrial events. For these bursts, localization is the key for burst identification and classification as well as follow-up observations in multi-wavelength. Here, we propose a Bayesian localization method with Poisson data with Gaussian background profile likelihood to localize GECAM bursts based on the burst counts distribution in detectors with different orientations. We demonstrate that this method can work well for all kinds of bursts, especially for extremely short ones. In addition, we propose a new method to estimate the systematic error of localization based on a confidence level test, which can overcome some problems of the existing method in literature. We validate this method by Monte Carlo simulations, and then apply it to a burst sample with accurate location and find that the mean value of the systematic error of GECAM-B localization is $\sim 2.5^{\circ}$. By considering this systematic error, we can obtain a reliable localization probability map for GECAM bursts. Our methods can be applied to other gamma-ray monitors.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Realtime trigger and localization of bursts are the key functions of GECAM, which is an all-sky gamma-ray monitor launched in Dec 10, 2020. We developed a multifunctional trigger and localization software operating on the CPU of the GECAM electronic box (EBOX). This onboard software has the following features: high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation, dedicated localization algorithm optimized for short and long bursts respetively, short time latency of the trigger information which is downlinked throught the BeiDou satellite navigation System (BDS). This paper presents the detailed design and deveopment of this trigger and localization software system of GECAM, including the main functions, general design, workflow and algorithms, as well as the verification and demonstration of this software, including the on-ground trigger tests with simulated gamma-ray bursts made by a dedicated X-ray tube and the in-flight performance to real gamma-ray bursts and magnetar bursts.