The isotope shifts of the 282 1S0 to 2s2p 1P1 and 3P1 transitions in the four-electron beryllium atom are calcu- lated by using the multi-configuration Dirac-Hartrce-Fock method and the relativistic configuration inte...The isotope shifts of the 282 1S0 to 2s2p 1P1 and 3P1 transitions in the four-electron beryllium atom are calcu- lated by using the multi-configuration Dirac-Hartrce-Fock method and the relativistic configuration interaction approach for the stable and short-Bved beryllium isotopes. The results provided herein can be employed for the consistency check with the nuclear rms charge radii from the experimental isotope shifts by using the correspond- ing transitions for the short-lived nuclei 7,10-12Be and 14 Be. The analogous isotope shift results could also be obtained for the beryllium-like ions by the methods used here.展开更多
EDITOR’S NOTE: With approval from Prince Regent Dagzha. the Lhasa English School opened in the Chongyi Lingka Villa on the 11th day of the sixth Tibetan month in July 1944. There were 43 students ,10 of whom were chi...EDITOR’S NOTE: With approval from Prince Regent Dagzha. the Lhasa English School opened in the Chongyi Lingka Villa on the 11th day of the sixth Tibetan month in July 1944. There were 43 students ,10 of whom were children of ordinary people and 33 of whom were children of aristocrats. But the school survived only for five months.展开更多
In recent years, extensive short-lived nuclear mass measurements have been carried out at the Heavy- Ion Research Facility （HIRFL） in Lanzhou using Isochronous Mass Spectrometry （IMS）. The obtained mass values hav...In recent years, extensive short-lived nuclear mass measurements have been carried out at the Heavy- Ion Research Facility （HIRFL） in Lanzhou using Isochronous Mass Spectrometry （IMS）. The obtained mass values have been successfully applied to nuclear structure and astrophysics studies. In this contribution, we give a brief introduction to the nuclear mass measurements at HIRFL-CSR facility. Main technical developments are described and recent results are summarized. Furthermore, we envision the future perspective for the next-generation storage ring facility HIAF in Huizhou.展开更多
The spin polarized β-emitting nuclei12B (I π=1+,T 1/2=20.18 ms) were produced by the nuclear reaction11B(d, p)12B and by the selection technique of the incident deuteron energy and the12B recoil angle following the ...The spin polarized β-emitting nuclei12B (I π=1+,T 1/2=20.18 ms) were produced by the nuclear reaction11B(d, p)12B and by the selection technique of the incident deuteron energy and the12B recoil angle following the nuclear reaction. The nuclear magnetic moment of the short-lived nuclei12B was measured by β-NMR with the β-NMR and β-NQR setup established for the first time in China. The nuclear magnetic moment of12B was determined to be μ=0.99993±0.00048 nm org=0.99993±0.00048 after the precise correction of the Knight shift.展开更多
Using daily maximum temperature(Tmax)data from 516 observation stations in eastern China from 1981 to 2020,this study employed a relative threshold method to define short-and long-lived heat waves(HWs)by considering r...Using daily maximum temperature(Tmax)data from 516 observation stations in eastern China from 1981 to 2020,this study employed a relative threshold method to define short-and long-lived heat waves(HWs)by considering regional climate differences to investigate the spatial characteristics and evolution of large-scale circulation during summer HWs.The results demonstrated spatial disparities in the frequency distribution of HWs of different durations and differences in the magnitude of duration and intensity between short-and long-lived HWs.Empirical orthogonal function analysis revealed three dominant spatial modes for both short-and long-lived HWs.The first mode showed that short-lived HWs occur prominently in both northern and southern regions,whereas long-lived HWs mainly occur in the northern region.The second mode was characterized by a meridional dipole pattern in both cases.The third mode exhibited a quadrupole pattern for short-lived HWs and a tripole pattern for long-lived HWs.Differences in the center locations of anomalies in the 500-hPa geopotential height and 850-hPa wind fields significantly influenced the temperature and precipitation anomaly distribution of typical HWs by affecting the warm column in the lower troposphere,cloud distribution,and moisture transport.Moreover,the atmospheric circulation evolution processes of typical HWs associated with the different modes of long-and short-lived HWs were linked to distinct teleconnection patterns.During the three modes of long-lived(short-lived)HWs,there was stronger(weaker)wave flux activity with multiple(single)propagation paths.Stronger westward Atlantic wave train activity at 300 hPa triggered the synergistic action of meridional and zonal wave fluxes,favoring the strengthening and maintenance of positive anomalies in geopotential height of 500 hPa.This may have contributed to the formation of long-lived HWs.These findings provide valuable insights to enhance our understanding and prediction of summer HWs.展开更多
There are many short-lived animals,but those displaying a lifecycle with more than one generation per year(multivoltine lifecycle)are rare amongterrestrial vertebrates.The multivoltine lifecycle requires rapid growth ...There are many short-lived animals,but those displaying a lifecycle with more than one generation per year(multivoltine lifecycle)are rare amongterrestrial vertebrates.The multivoltine lifecycle requires rapid growth and maturation and a long active season.Thus,small lizards in humidtropical or subtropical areas are candidates for multivoltine lifecycles.To test this prediction,we conducted a capture-mark-recapture study of asubtropical grass lizard,Takydromus toyamai,endemic to Miyako Islands,Japan.Juveniles grew very quickly,averaging 0.3 mm/day in the warmseason,and attained sexual maturity at 2.5 months post-hatching.The breeding season was very long,and hatchlings emerged from May toNovember.The prolonged breeding season and rapid growth to maturity allowed some individuals to produce a second generation in their frstyear.Estimates of hatching date from growth rates indicated that many females that hatched in May-June became gravid 76-120 days afterhatching and 122-165 days after oviposition of the eggs from which they hatched.Analyses of juvenile survivorship and month of hatching suggest that nearly half of breeding adults were members of multivoltine generations,although the 2 generations were not discrete.The species isshort-lived,with only 16% of individuals surviving beyond 12 months,and few individuals reproduced in a second year.We refer to this conditionas a“semi-multivoltine lifecycle.”Individuals that hatch late in the season defer reproduction until the following year and become founders ofthe next season’s cohort.This putative advantage of late-hatching individuals may have driven the evolution of this lifecycle.展开更多
SISAK(Short-lived Isotopes Studies by the AKUFVE technique)技术是目前使用最广泛的快速化学分离方法之一,主要应用在短寿命核素的分离和鉴别、超重元素的人工合成以及化学性质研究等方面的工作中。本文简单地叙述了SISAK技术的流...SISAK(Short-lived Isotopes Studies by the AKUFVE technique)技术是目前使用最广泛的快速化学分离方法之一,主要应用在短寿命核素的分离和鉴别、超重元素的人工合成以及化学性质研究等方面的工作中。本文简单地叙述了SISAK技术的流程、原理和发展现状,介绍了自行建立的国内第一套基于SISAK技术的快速化学分离装置,并通过从裂变产物中分离短寿命核素这一实例验证了SISAK技术在快速化学分离中的优越性。展开更多
The pulsed nuclear reactor was used to measure the effect of neutrinos on the beta-decay of 90Sr/90Y nuclei. This measurement shows that some increase in the decay rate occurs in a few tens of milliseconds after react...The pulsed nuclear reactor was used to measure the effect of neutrinos on the beta-decay of 90Sr/90Y nuclei. This measurement shows that some increase in the decay rate occurs in a few tens of milliseconds after reactor flashes.展开更多
Detection and observation of reactive intermediates is an essential step in investigation of reaction pathways.However,most reactive intermediates are unstable and present at low concentrations;their short lifetimes m...Detection and observation of reactive intermediates is an essential step in investigation of reaction pathways.However,most reactive intermediates are unstable and present at low concentrations;their short lifetimes make them difficult to detect and characterize.Supramolecular containers offer opportunities for the stabilization and characterization of those labile species,through isolation from the media and protection inside the cavity of the host.In this review,we summarize the examples of labile reaction intermediates that are stabilized and characterized with the help of supramolecular containers.The container compounds include carcerands,deep cavitands and amide naphthotubes.We focus on unstable vip species-cyclobutadiene,benzocyclopropenone,o-benzyne,1,2,4,6-cycloheptatetraene,anti-Bredt's olefin,fluorophenoxycarbene,O-acylisoamide,and hemiaminalthat act as intermediates in certain organic reactions.展开更多
The use of thallium(I) hydroxide (TlOH) as a base is known to extremely accelerate the Suzuki-Miyaura cross-coupling reaction using organoboronic acid or organoboronic acid ester as a substrate. Here, we investigated ...The use of thallium(I) hydroxide (TlOH) as a base is known to extremely accelerate the Suzuki-Miyaura cross-coupling reaction using organoboronic acid or organoboronic acid ester as a substrate. Here, we investigated the effects of TlOH by comparing with other conventional bases such as KOH, K2CO3, and CsF for Pd0-mediated rapid cross-coupling reactions between CH3I and organoborane reagents, such as phenyl-, (Z)-4-benzyloxy-2-butenyl-, and benzylboronic acid pinacol esters under the conditions CH3I/borane/Pd0/base (1:40:1:3) in THF/H2O or DMF/H2O for 5 min with an aim to fabricate a PET tracer efficiently. Consequently, however, the use of TlOH was much less efficient than the other bases for the acceleration of cross-coupling reactions. Thus, it was reconfirmed that the milder and non-toxic conditions using K2CO3 or CsF so far developed by our group were most appropriate for the rapid C-methylations.展开更多
The reproductive ability related to the population size of the endangered and endemic species Primula merrilliana Schltr. was investigated. In 26 populations observed, only four contain more than 500 flowering individ...The reproductive ability related to the population size of the endangered and endemic species Primula merrilliana Schltr. was investigated. In 26 populations observed, only four contain more than 500 flowering individuals, whereas most of them （53.8%） consist of less than 100 flowering individuals. Though the ratio of pin and thrum plants keeps its balance at 1：1 for all populations, the frequency of pin and thrum flowers was significantly biased in most small populations. Population size strongly affected reproductive success; plants in small populations produced significantly fewer flowers and fruits per plant and fewer seeds per fruit, and therefore fewer seeds per plant. The floral density was another important factor that influenced the reproductive success of P. merrilliana, because four main reproductive success parameters （fruits per plant, seeds per fruit, seeds per plant, and the proportion of flowers setting fruit） were all positively correlated with floral density. The size of plants and the number of leaves per plant （measure of habitat quality） were not influenced by the variation of population size, suggesting that the reduced fecundity in small populations may not be a consequence of lower habitat quality. Inbreeding depression and pollen limitation as a result of less attractiveness in small populations are therefore likely explanations for these patterns.展开更多
基金Supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department under Grant No 14JK1402
文摘The isotope shifts of the 282 1S0 to 2s2p 1P1 and 3P1 transitions in the four-electron beryllium atom are calcu- lated by using the multi-configuration Dirac-Hartrce-Fock method and the relativistic configuration interaction approach for the stable and short-Bved beryllium isotopes. The results provided herein can be employed for the consistency check with the nuclear rms charge radii from the experimental isotope shifts by using the correspond- ing transitions for the short-lived nuclei 7,10-12Be and 14 Be. The analogous isotope shift results could also be obtained for the beryllium-like ions by the methods used here.
文摘EDITOR’S NOTE: With approval from Prince Regent Dagzha. the Lhasa English School opened in the Chongyi Lingka Villa on the 11th day of the sixth Tibetan month in July 1944. There were 43 students ,10 of whom were children of ordinary people and 33 of whom were children of aristocrats. But the school survived only for five months.
文摘In recent years, extensive short-lived nuclear mass measurements have been carried out at the Heavy- Ion Research Facility （HIRFL） in Lanzhou using Isochronous Mass Spectrometry （IMS）. The obtained mass values have been successfully applied to nuclear structure and astrophysics studies. In this contribution, we give a brief introduction to the nuclear mass measurements at HIRFL-CSR facility. Main technical developments are described and recent results are summarized. Furthermore, we envision the future perspective for the next-generation storage ring facility HIAF in Huizhou.
基金This work was supported by the National Natural Science Foundation of China(Grant No.10175088)also partially supported by the Japan Society for the Promotion of Science for the Joint Research Project under the Japan-China Scientific cooperation program.
文摘The spin polarized β-emitting nuclei12B (I π=1+,T 1/2=20.18 ms) were produced by the nuclear reaction11B(d, p)12B and by the selection technique of the incident deuteron energy and the12B recoil angle following the nuclear reaction. The nuclear magnetic moment of the short-lived nuclei12B was measured by β-NMR with the β-NMR and β-NQR setup established for the first time in China. The nuclear magnetic moment of12B was determined to be μ=0.99993±0.00048 nm org=0.99993±0.00048 after the precise correction of the Knight shift.
基金Supported by the National Key Research and Development Program of China(2022YFF0801603).
文摘Using daily maximum temperature(Tmax)data from 516 observation stations in eastern China from 1981 to 2020,this study employed a relative threshold method to define short-and long-lived heat waves(HWs)by considering regional climate differences to investigate the spatial characteristics and evolution of large-scale circulation during summer HWs.The results demonstrated spatial disparities in the frequency distribution of HWs of different durations and differences in the magnitude of duration and intensity between short-and long-lived HWs.Empirical orthogonal function analysis revealed three dominant spatial modes for both short-and long-lived HWs.The first mode showed that short-lived HWs occur prominently in both northern and southern regions,whereas long-lived HWs mainly occur in the northern region.The second mode was characterized by a meridional dipole pattern in both cases.The third mode exhibited a quadrupole pattern for short-lived HWs and a tripole pattern for long-lived HWs.Differences in the center locations of anomalies in the 500-hPa geopotential height and 850-hPa wind fields significantly influenced the temperature and precipitation anomaly distribution of typical HWs by affecting the warm column in the lower troposphere,cloud distribution,and moisture transport.Moreover,the atmospheric circulation evolution processes of typical HWs associated with the different modes of long-and short-lived HWs were linked to distinct teleconnection patterns.During the three modes of long-lived(short-lived)HWs,there was stronger(weaker)wave flux activity with multiple(single)propagation paths.Stronger westward Atlantic wave train activity at 300 hPa triggered the synergistic action of meridional and zonal wave fluxes,favoring the strengthening and maintenance of positive anomalies in geopotential height of 500 hPa.This may have contributed to the formation of long-lived HWs.These findings provide valuable insights to enhance our understanding and prediction of summer HWs.
基金supported fnancially by the Nanseishoto Project of WWFJ,Pro Natura Foundation Japan’s 31st Pro Natura Fundthe Project for Biodiversity Conservation Promotion of the Japan Ministry of the Environment.
文摘There are many short-lived animals,but those displaying a lifecycle with more than one generation per year(multivoltine lifecycle)are rare amongterrestrial vertebrates.The multivoltine lifecycle requires rapid growth and maturation and a long active season.Thus,small lizards in humidtropical or subtropical areas are candidates for multivoltine lifecycles.To test this prediction,we conducted a capture-mark-recapture study of asubtropical grass lizard,Takydromus toyamai,endemic to Miyako Islands,Japan.Juveniles grew very quickly,averaging 0.3 mm/day in the warmseason,and attained sexual maturity at 2.5 months post-hatching.The breeding season was very long,and hatchlings emerged from May toNovember.The prolonged breeding season and rapid growth to maturity allowed some individuals to produce a second generation in their frstyear.Estimates of hatching date from growth rates indicated that many females that hatched in May-June became gravid 76-120 days afterhatching and 122-165 days after oviposition of the eggs from which they hatched.Analyses of juvenile survivorship and month of hatching suggest that nearly half of breeding adults were members of multivoltine generations,although the 2 generations were not discrete.The species isshort-lived,with only 16% of individuals surviving beyond 12 months,and few individuals reproduced in a second year.We refer to this conditionas a“semi-multivoltine lifecycle.”Individuals that hatch late in the season defer reproduction until the following year and become founders ofthe next season’s cohort.This putative advantage of late-hatching individuals may have driven the evolution of this lifecycle.
文摘SISAK(Short-lived Isotopes Studies by the AKUFVE technique)技术是目前使用最广泛的快速化学分离方法之一,主要应用在短寿命核素的分离和鉴别、超重元素的人工合成以及化学性质研究等方面的工作中。本文简单地叙述了SISAK技术的流程、原理和发展现状,介绍了自行建立的国内第一套基于SISAK技术的快速化学分离装置,并通过从裂变产物中分离短寿命核素这一实例验证了SISAK技术在快速化学分离中的优越性。
文摘The pulsed nuclear reactor was used to measure the effect of neutrinos on the beta-decay of 90Sr/90Y nuclei. This measurement shows that some increase in the decay rate occurs in a few tens of milliseconds after reactor flashes.
基金supported by the National Natural Science Foundation of China(Nos.22071144 and 22101169)Shanghai Scientific and Technological Committee(No.22010500300)。
文摘Detection and observation of reactive intermediates is an essential step in investigation of reaction pathways.However,most reactive intermediates are unstable and present at low concentrations;their short lifetimes make them difficult to detect and characterize.Supramolecular containers offer opportunities for the stabilization and characterization of those labile species,through isolation from the media and protection inside the cavity of the host.In this review,we summarize the examples of labile reaction intermediates that are stabilized and characterized with the help of supramolecular containers.The container compounds include carcerands,deep cavitands and amide naphthotubes.We focus on unstable vip species-cyclobutadiene,benzocyclopropenone,o-benzyne,1,2,4,6-cycloheptatetraene,anti-Bredt's olefin,fluorophenoxycarbene,O-acylisoamide,and hemiaminalthat act as intermediates in certain organic reactions.
文摘The use of thallium(I) hydroxide (TlOH) as a base is known to extremely accelerate the Suzuki-Miyaura cross-coupling reaction using organoboronic acid or organoboronic acid ester as a substrate. Here, we investigated the effects of TlOH by comparing with other conventional bases such as KOH, K2CO3, and CsF for Pd0-mediated rapid cross-coupling reactions between CH3I and organoborane reagents, such as phenyl-, (Z)-4-benzyloxy-2-butenyl-, and benzylboronic acid pinacol esters under the conditions CH3I/borane/Pd0/base (1:40:1:3) in THF/H2O or DMF/H2O for 5 min with an aim to fabricate a PET tracer efficiently. Consequently, however, the use of TlOH was much less efficient than the other bases for the acceleration of cross-coupling reactions. Thus, it was reconfirmed that the milder and non-toxic conditions using K2CO3 or CsF so far developed by our group were most appropriate for the rapid C-methylations.
基金National Natural Science Foundation of China General Projects (30500300)the Natural Science Foundation of Anhui Province (050430501)+1 种基金the Doctoral Subject Foundation of High College of Chinese Education Commission (20060370001) the Foundation for Junior Teacher of Anhui Education Department (2005jq1051)
文摘The reproductive ability related to the population size of the endangered and endemic species Primula merrilliana Schltr. was investigated. In 26 populations observed, only four contain more than 500 flowering individuals, whereas most of them （53.8%） consist of less than 100 flowering individuals. Though the ratio of pin and thrum plants keeps its balance at 1：1 for all populations, the frequency of pin and thrum flowers was significantly biased in most small populations. Population size strongly affected reproductive success; plants in small populations produced significantly fewer flowers and fruits per plant and fewer seeds per fruit, and therefore fewer seeds per plant. The floral density was another important factor that influenced the reproductive success of P. merrilliana, because four main reproductive success parameters （fruits per plant, seeds per fruit, seeds per plant, and the proportion of flowers setting fruit） were all positively correlated with floral density. The size of plants and the number of leaves per plant （measure of habitat quality） were not influenced by the variation of population size, suggesting that the reduced fecundity in small populations may not be a consequence of lower habitat quality. Inbreeding depression and pollen limitation as a result of less attractiveness in small populations are therefore likely explanations for these patterns.
