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  • 1
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2024
    In:  Acta Physica Sinica Vol. 73, No. 7 ( 2024), p. 072801-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 73, No. 7 ( 2024), p. 072801-
    Abstract: Neutron capture reaction is one of the neutron reactions and plays an important role in using reactor control rods and shell materials, designing nuclear device structures, and studying nuclear astrophysics S processes and element origins. The 4π BaF 〈 sub 〉 2 〈 /sub 〉 detection device has advantages such as high time resolution, low neutron sensitivity, and high detection efficiency, thus making it suitable for measuring neutron radiation capture reaction cross-section data. In order to fill the gap in our neutron capture reaction data in the keV energy range and improve their accuracy, the Key Laboratory of Nuclear Data at the Chinese Institute of Atomic Energy (CIAE) has established a Gamma Total Absorption Facility (GTAF), which consists of 28 hexagonal BaF 〈 sub 〉 2 〈 /sub 〉 crystals and 12 pentagonal BaF 〈 sub 〉 2 〈 /sub 〉 crystals to form a spherical shell with an external diameter of 25 cm and an internal diameter of 10 cm, covering 95.2% of the solid angles. The Back-n beam line of the Chinese Spallation Neutron Source (CSNS) is a back-streaming white beam line that covers neutron energy ranging from a few eV to several hundred MeV, making it suitable for measuring neutron capture cross-sections. The reaction cross-section data of 〈 sup 〉 197 〈 /sup 〉 Au is measured by using GTAF on the Back-n beam line. The measurement data are preliminarily background deducted through energy screening, PSD method, and crystal multiplicity screening. Subsequently, the background is analyzed and deducted based on the measurement data of 〈 sup 〉 nat 〈 /sup 〉 C and empty samples, and the yield of 〈 sup 〉 197 〈 /sup 〉 Au capture reaction is obtained. Resonance parameters are a set of parameters extracted from experimental data to describe the resonance curve, which can eliminate the influence of experimental conditions on resonance data and are more important than the cross-section obtained from experiments. The resonance energy, neutron resonance width, and gamma resonance width parameters of 〈 sup 〉 197 〈 /sup 〉 Au at 1–100 eV are fitted by using the SAMMY program. From the comparison between the resonance curves obtained from experimental measurements and the resonance parameters obtained from fitting with the ENDF/B-VIII.0 database, it can follow that the experimental measurement results are in good agreement with the database, nevertheless, there exist some differences in the resonance parameter, which may be due to the GTAF energy resolution, Back-n neutron spectrum measurement accuracy, and the experimental background deduction method. Our next work is to identify the sources of difference.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2024
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  • 2
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2021
    In:  Acta Physica Sinica Vol. 70, No. 8 ( 2021), p. 082901-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 70, No. 8 ( 2021), p. 082901-
    Abstract: At present, there exist few proton-beam terminals for the detector calibration in the world. Meanwhile, most of these terminals provide monoenergetic protons. Back-n white neutron source from China Spallation Neutron Source(CSNS) was put into operation in 2018. Based on the white neutron flux ranging from 0.5 eV to 200 MeV from the CSNS Back-n white neutron source, continuous-energy protons involved in a wide energy spectrum can be acquired from the 〈sup〉1〈/sup〉H(n, el) reaction. Adopting this method, a new research platform for researches such as proton calibration is realized at CSNS. As hydrogen exists as gas at normal temperature and pressure, in the selecting of the proton-converting target, the hydrogen-rich compounds are preferential considered. Considering the reaction cross sections of the 〈sup〉1〈/sup〉H(n, el), 〈sup〉12〈/sup〉C(n, p)〈sup〉12〈/sup〉B, 〈sup〉12〈/sup〉C(n, d)〈sup〉11〈/sup〉B, 〈sup〉12〈/sup〉C(n, t)〈sup〉10〈/sup〉B, 〈sup〉12〈/sup〉C(n, 〈sup〉3〈/sup〉He)〈sup〉10〈/sup〉Be, 〈sup〉12〈/sup〉C(n, α)〈sup〉9〈/sup〉Be and 〈sup〉1〈/sup〉H(n, γ)〈sup〉2〈/sup〉H, polyethylene and polypropylene are suitable for serving as targets in this research. Based on a 3U PXIe, digitizers with 1 GSps sampling rate and 12 bit resolution are utilized to digitize and record the output signals of telescopes. The time and amplitude information of each signal are extracted from its recorded waveform. Proton fluxes can be calculated by using the neutron energy spectrum and the cross section of the 〈sup〉1〈/sup〉H(n, el) reaction. Using the γ-flash event as the starting time of the time-of-flight (TOF) and the time information of signal in detector as the stopping time, the kinematic energy of each secondary proton can be deduced from the TOF and the angle of the detector. A calibration experiment on three charged particle telescopes, with each telescope consisting of a silicon detector and a CsI(Tl) detector, is carried out on this research platform. The readout methods of the CsI(Tl) detectors in these three telescopes are different. In the calibration experiment, Δ〈i〉E-〈/i〉〈i〉E〈/i〉 two-dimensional spectra and amplitude-〈i〉E〈/i〉〈sub〉p〈/sub〉 two-dimensional spectra of these telescopes are obtained. Through comparing these particle identification spectra, the SiPM is chosen as the signal readout method for CsI(Tl) detectors in the charged particle telescopes. These researches provide experimental evidence for the construction of the charged particle telescope at Back-n, and also illustrate the feasibility of wide-energy spectrum proton calibration based on the Back-n white neutron source.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2021
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  • 3
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2021
    In:  Acta Physica Sinica Vol. 70, No. 22 ( 2021), p. 222801-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 70, No. 22 ( 2021), p. 222801-
    Abstract: The data of neutron capture cross section are very important for the research of nuclear astrophysics, advanced nuclear energy development. Owing to the limitation of neutron source and detector, the experimental data of neutron capture cross section in an energy range of 1 eV–10 keV were almost blank in China. The first Chinese gamma-ray total absorption facility has been constructed in the key laboratory of nuclear data at China institute of atomic energy, which consists of 40 BaF〈sub〉2〈/sub〉 detector units. The BaF〈sub〉2〈/sub〉 crystal shell with a thickness of 15 cm and an inner radius of 10 cm covers 95.2% of the solid angle. On-line measurement method of neutron capture reaction cross section is established on the back-streaming white neutron source of China spallation neutron source by using the upgraded facility. The cross section of 〈sup〉197〈/sup〉Au neutron capture reaction is measured for the first time under the experimental condition of irregular 30 mm neutron beam spot. The measured position of resonance peak is well consistent with the relevant data of ENDF evaluation database, which verifies the reliability of the measurement device and measurement technology, and thus laying the foundation for the acquisition of high precision cross section in future.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2021
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  • 4
    Online Resource
    Online Resource
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2020
    In:  Acta Physica Sinica Vol. 69, No. 17 ( 2020), p. 172901-
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 69, No. 17 ( 2020), p. 172901-
    Abstract: The back-streaming neutron beam line (Back-n) was built in the beginning of 2018, which is part of the China Spallation Neutron Source (CSNS). The Back-n is the first white neutron beam line in China, and its main application is for nuclear data measurement. For most of neutron-induced nuclear reaction measurements based on white neutron facilities, the beam of gamma rays accompanied with neutron beam is one of the most important experimental backgrounds. The back streaming neutron beam is transported directly from the spallation target to the experimental station without any moderator or shielding, the flux of the in-beam gamma rays in the experimental station is much larger than those of these facilities with neutron moderator and shielding. Therefore, it is necessary to consider the influence of in-beam gamma rays on the experimental results. Studies of the in-beam gamma rays are carried out at the back-n. Monte-Carlo simulation is employed to obtain the energy distribution and the time structure of the in-beam gamma rays. According to the simulation results, when the neutron flight time is longer than 1.0 μs the energy distribution of the in-beam gamma rays does not vary with flight time. Therefore, the time structure of these gamma rays can be measured without the correction of the detection efficiency. In this work, the time structure of the in-beam gamma rays in the low neutron energy region is measured by both direct and indirect methods. In the direct measurement, a 〈sup〉6〈/sup〉Li loaded ZnS(Ag) scintillator is located on the neutron beam line and the time of flight method is used to determine the time structure of neutrons and gamma rays. The gamma rays are separated from neutrons with pulse-shape discrimination. The black filter method is used to verify the particle discrimination results. In the indirect measurement, the C〈sub〉6〈/sub〉D〈sub〉6〈/sub〉 scintillation detectors are used to measure the gamma rays scattered off a Pb sample on the way of the neutron beam. The time structure of the in-beam gamma rays is derived from that of the scattered gamma rays. The experimental results are in good agreement with the simulations with the time-of-flight between 12 μs and 2.0 ms. Besides, according to the simulation results, the intensity of the in-beam gamma rays is 1.21 × 10〈sup〉6〈/sup〉 s〈sup〉–1〈/sup〉·cm〈sup〉–2〈/sup〉 in the center of the experimental station 2 of Back-n, which is 76.5 m away from the spallation target of CSNS.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2020
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  • 5
    In: Nuclear Science and Techniques, Springer Science and Business Media LLC, Vol. 34, No. 8 ( 2023-08)
    Type of Medium: Online Resource
    ISSN: 1001-8042 , 2210-3147
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2238719-5
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  • 6
    In: Nuclear Science and Techniques, Springer Science and Business Media LLC, Vol. 32, No. 1 ( 2021-01)
    Type of Medium: Online Resource
    ISSN: 1001-8042 , 2210-3147
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2238719-5
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  • 7
    In: Molecules, MDPI AG, Vol. 28, No. 4 ( 2023-02-10), p. 1721-
    Abstract: π-Extended pyrene compounds possess remarkable luminescent and semiconducting properties and are being intensively investigated as electroluminescent materials for potential uses in organic light-emitting diodes, transistors, and solar cells. Here, the synthesis of two sets of pyrene-containing π-conjugated polyaromatic regioisomers, namely 2,3,10,11,14,15,20,21-octaalkyloxypentabenzo[a,c,m,o,rst]pentaphene (BBPn) and 2,3,6,7,13,14,17,18-octaalkyloxydibenzo[j,tuv]phenanthro [9,10-b] picene (DBPn), is reported. They were obtained using the Suzuki–Miyaura cross-coupling in tandem with Scholl oxidative cyclodehydrogenation reactions from the easily accessible precursors 1,8- and 1,6-dibromopyrene, respectively. Both sets of compounds, equipped with eight peripheral aliphatic chains, self-assemble into a single hexagonal columnar mesophase, with one short-chain BBPn homolog also exhibiting another columnar mesophase at a lower temperature, with a rectangular symmetry; BBPn isomers also possess wider mesophase ranges and higher mesophases’ stability than their DBPn homologs. These polycyclic aromatic hydrocarbons all show a strong tendency of face-on orientation on the substrate and could be controlled to edge-on alignment through mechanical shearing of interest for their implementation in photoelectronic devices. In addition, both series BBPn and DBPn display green-yellow luminescence, with high fluorescence quantum yields, around 30%. In particular, BBPn exhibit a blue shift phenomenon in both absorption and emission with respect to their DBPn isomers. DFT results were in good agreement with the optical properties and with the stability ranges of the mesophases by confirming the higher divergence from the flatness of DBPn compared with BBPn. Based on these interesting properties, these isomers could be potentially applied not only in the field of fluorescent dyes but also in the field of organic photoelectric semiconductor materials as electron transport materials.
    Type of Medium: Online Resource
    ISSN: 1420-3049
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2008644-1
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  • 8
    In: BMC Health Services Research, Springer Science and Business Media LLC, Vol. 12, No. 1 ( 2012-12)
    Abstract: Neonatal hearing screening (NHS) has been routinely offered as a vital component of early childhood care in developed countries, whereas such a screening program is still at the pilot or preliminary stage as regards its nationwide implementation in developing countries. To provide significant evidence for health policy making in China, this study aims to determine the cost-effectiveness of NHS program implementation in case of eight provinces of China. Methods A cost-effectiveness model was conducted and all neonates annually born from 2007 to 2009 in eight provinces of China were simulated in this model. The model parameters were estimated from the established databases in the general hospitals or maternal and child health hospitals of these eight provinces, supplemented from the published literature. The model estimated changes in program implementation costs, disability-adjusted life years (DALYs), average cost-effectiveness ratio (ACER), and incremental cost-effectiveness ratio (ICER) for universal screening compared to targeted screening in eight provinces. Results and discussion A multivariate sensitivity analysis was performed to determine uncertainty in health effect estimates and cost-effectiveness ratios using a probabilistic modeling technique. Targeted strategy trended to be cost-effective in Guangxi, Jiangxi, Henan, Guangdong, Zhejiang, Hebei, Shandong, and Beijing from the level of 9%, 9%, 8%, 4%, 3%, 7%, 5%, and 2%, respectively; while universal strategy trended to be cost-effective in those provinces from the level of 70%, 70%, 48%, 10%, 8%, 28%, 15%, 4%, respectively. This study showed although there was a huge disparity in the implementation of the NHS program in the surveyed provinces, both universal strategy and targeted strategy showed cost-effectiveness in those relatively developed provinces, while neither of the screening strategy showed cost-effectiveness in those relatively developing provinces. This study also showed that both strategies especially universal strategy achieve a good economic effect in the long term costs. Conclusions Universal screening might be considered as the prioritized implementation goal especially in those relatively developed provinces of China as it provides the best health and economic effects, while targeted screening might be temporarily more realistic than universal screening in those relatively developing provinces of China.
    Type of Medium: Online Resource
    ISSN: 1472-6963
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2012
    detail.hit.zdb_id: 2050434-2
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  • 9
    Online Resource
    Online Resource
    Royal Society of Chemistry (RSC) ; 2022
    In:  Journal of Materials Chemistry C Vol. 10, No. 39 ( 2022), p. 14453-14470
    In: Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), Vol. 10, No. 39 ( 2022), p. 14453-14470
    Abstract: The synthesis of an exclusive family of liquid-crystalline dimers consisting of two protomesogenic triphenylene moieties connected via a rigid, π-conjugated bridge, and the study of their mesomorphous, gel self-assembly and optical properties as a function of the nature of the bridge are reported. Various triphenylene bridged dimers were successfully prepared by either palladium-catalyzed Suzuki–Miyaura cross-coupling between pentakis(alkoxy)triphenylene nonaflates and various commercially accessible aryldiboronic acids (as bridges) or by FeCl 3 -promoted Scholl oxidative homo-coupling of thiophene/thienothiophene/furan-containing pentakis(alkoxy)triphenylene derivatives. All linear dimers are mesomorphous, and self-organize into large multi-columnar rectangular superlattices, with columnar pairs arranged according to a chevron-like pattern, as deduced from SWAXS and supported by STM. At high temperature, most compounds also display a nematic columnar mesophase (N Col ), easily recognized by characteristic optical textures. The transition temperature and mesophase ranges show a high dependency on the bridge nature and, to a lesser extent, on the chain-lengths around the triphenylene moieties. The sole kinked bridged-dimeric homolog of this series exhibits a single, room-temperature hexagonal mesophase (Col hex ), as do the monofunctionalized triphenylene precursors, whereas the dimeric triphenylene with no bridge is not mesomorphous. UV-visible absorption and fluorescence emission spectra were measured in both solvents and thin films. The π-conjugated bridged-dimers exhibit emission spanning from 400–700 nm, thus covering the full visible-light range, whose emission maxima are obviously influenced by the chemical nature of the bridge. Furthermore, fluorescence quantum yields as high as 64% were measured for some of them. DFT theoretical computing calculations fully support the experimental measurements. Most dimers also form gels in cyclohexane and emit blue-to-orange light when irradiated by UV light; the corresponding xerogels revealed that their gelation ability results from the 3D morphology of entangled ultra-long and thin microfibers. The facile synthesis of these unique, multifunctional rigid discotic dimers, their rich mesomorphism, strong gelation ability and fine-tuned photophysical properties make these materials very attractive for the active field of organic electronics.
    Type of Medium: Online Resource
    ISSN: 2050-7526 , 2050-7534
    Language: English
    Publisher: Royal Society of Chemistry (RSC)
    Publication Date: 2022
    detail.hit.zdb_id: 2702245-6
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  • 10
    In: Neuropsychobiology, S. Karger AG, Vol. 61, No. 2 ( 2010), p. 71-78
    Abstract: 〈 i 〉 Background: 〈 /i 〉 Preclinical studies have shown that brain-derived neurotrophic factor (BDNF) may be involved in antidepressant action, and the 〈 i 〉 BDNF 〈 /i 〉 gene has been suggested to be involved in the pharmacological treatment of major depressive disorder (MDD). In this study, the relationship between BDNF Val66Met polymorphism (Single Nucleotide Polymorphism Database ID: rs6265) and severity of depression, efficacy of fluoxetine and its side effects was tested in Chinese patients with MDD. 〈 i 〉 Methods: 〈 /i 〉 Patients with MDD took the oral selective serotonin reuptake inhibitor (SSRI) fluoxetine (20 mg/day) for 6 weeks. Its clinical efficacy and side effects were measured by the 17-item Hamilton Rating Scale for Depression and the Treatment-Emergent Symptoms Scale (TESS), respectively. The patients were genotyped for Val66Met polymorphism of the 〈 i 〉 BDNF 〈 /i 〉 gene. 〈 i 〉 Results: 〈 /i 〉 In the multivariate regression analysis, there was no significant association between severity of depression and BDNF Val66Met polymorphism. There was no association between efficacy of fluoxetine and BDNF Val66Met polymorphism, but there was a marginal positive suggestion that heterozygous patients tended to have a better remission with fluoxetine in comparison with homozygous analogs. Insomnia and decreased sexual desire, side effects of fluoxetine, may have an association with the BDNF Val66Met polymorphism, and Met allele carriers showed a lower incidence of these side effects. 〈 i 〉 Conclusions: 〈 /i 〉 These results indicate that there was a lack of association between severity of depression and BDNF Val66Met polymorphism in Chinese patients with MDD. The BDNF Val66Met polymorphism may play a major role in the efficacy and side effects of SSRI (fluoxetine) in Chinese patients with MDD.
    Type of Medium: Online Resource
    ISSN: 0302-282X , 1423-0224
    Language: English
    Publisher: S. Karger AG
    Publication Date: 2010
    detail.hit.zdb_id: 1483094-2
    SSG: 5,2
    SSG: 15,3
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