Active precursor promoting nucleation/growth of MwW zeolite and controlling its morphology

MWW zeolites is an important catalyst in petrochemical industry.However,the efficient preparation of Mww zeolites still faces challenges,and the origin of influential factors for regulating its structure properties also remains obscure.Herein,we designed a nanoscale amorphous silica-alumina species denoted as active precursor(APS),and adopt the APS in the HMI mixture to synthesize MCM-22 zeolite(APS-MWW)successfully.To reveal the distinctive role of APS in promoting the crystallization of MWW zeolites,two crystal materials(ITQ-1 and MCM-22)and one mother liquor(ML)as seeds to synthesize three types of MWW zeolites.Typically,when adding APS in the synthetic mixture,the HMI amount was reduced to less than a quarter and crystallization time was reduced to 36 h.APS-MWW sample provides a smaller particle size(2-4μm)and thinner stacked layer thickness(5-20 nm).Synchrotron radiation Small Angle X-ray Scattering(SAXS)shows each seed has a different impact on the species'fractal structure and size distribution in the mixture,which is highly related to the nucleation and growth of MWW zeolites.APS shows a large number of 6 membered ring(MR)structure units which play a sig-nificant role in boosting the rapid nucleation and growth of APS-MwW zeolite.Among the synthesized MWW zeolites,the APS-MWW performs the highest ethylbenzene yield in the alkylation reaction of benzene-ethylene,which is attributed to its moderate flake thickness,appropriate texture properties and more external surface acidity.The results will provide a new perspective for producing MwW-types zeolites by using the available and effective active precursor.

Stepped-up development of accelerator mass spectrometry method for the detection of ^(60)Fe with the HI-13 tandem accelerator

The Moon provides a unique environment for investigating nearby astrophysical events such as supernovae.Lunar samples retain valuable information from these events,via detectable long-lived“fingerprint”radionuclides such as^(60)Fe.In this work,we stepped up the development of an accelerator mass spectrometry(AMS)method for detecting^(60)Fe using the HI-13tandem accelerator at the China Institute of Atomic Energy(CIAE).Since interferences could not be sufficiently removed solely with the existing magnetic systems of the tandem accelerator and the following Q3D magnetic spectrograph,a Wien filter with a maximum voltage of±60 kV and a maximum magnetic field of 0.3 T was installed after the accelerator magnetic systems to lower the detection background for the low abundance nuclide^(60)Fe.A 1μm thick Si_(3)N_(4) foil was installed in front of the Q3D as an energy degrader.For particle detection,a multi-anode gas ionization chamber was mounted at the center of the focal plane of the spectrograph.Finally,an^(60)Fe sample with an abundance of 1.125×10^(-10)was used to test the new AMS system.These results indicate that^(60)Fe can be clearly distinguished from the isobar^(60)Ni.The sensitivity was assessed to be better than 4.3×10^(-14)based on blank sample measurements lasting 5.8 h,and the sensitivity could,in principle,be expected to be approximately 2.5×10^(-15)when the data were accumulated for 100 h,which is feasible for future lunar sample measurements because the main contaminants were sufficiently separated.

Green and efficient dry gel conversion synthesis of SAPO-34 catalyst with plate-like morphology

SAPO-34 catalyst with plate-like morphology was designed and synthesized for the first time, by the dry gel conversion method using cheap triethylamine as a structure-directing agent assisted with seed suspension containing nanosheet-like SAPO-34 seed. The latter played an important role in formation of SAPO-34 （CHA-type） with plate-like morphology. In addition, the yield of the product in the synthesis system containing seed suspension reached 97%, 15% higher than that obtained in the corre- sponding synthesis system without the seed suspension. Meanwhile, the plate-like SAPO-34 catalysts synthesized by this method exhibited higher selectivity to light olefins and longer lifetime in methanol-to-olefins （MTO） reaction than the traditional cubic SAPO-34 catalyst. This work provides a new technical route for green and efficient synthesis of SAPO-34 catalysts with improved MTO performance.

First proof-of-principle experiment with the post-accelerated isotope separator on-line beam at BRIF:measurement of the angular distribution of ^(23)Na+^(40)Ca elastic scattering

The reaction dynamics of exotic nuclei near the drip line is one of the main research topics of current interest.Elastic scattering is a useful probe for investigating the size and surface diffuseness of exotic nuclei.The development of rare isotope accelerators offers opportunities for such studies.To date,many relevant measurements have been performed at accelerators using the projectile fragmentation technique,while the measurements at accelerators using isotope separator on-line(ISOL)systems are still quite scarce.In this work,we present the first proof-of-principle experiment with a post-accelerated ISOL beam at the Beijing Radioactive Ion Beam Facility(BRIF)by measuring the angular distribution of elastic scattering for the stable nucleus^(23)Na from the doubly magic nucleus^(40)Ca at energies above the Coulomb barrier.The angular distribution measured by a silicon strip detector array in a scattering chamber using the ISOL beam at BRIF is in good agreement with that measured by the high-precision Q3 D magnetic spectrograph using the nonISOL beam at nearly the same energy.This work provides useful background for making BRIF a powerful tool for the investigation of the reaction dynamics of exotic nuclei.

Preparation of sol-gel derived microcrystalline corundum abrasives with hexagonal platelets

The effects of different additives on the mechanical properties, microstructures, and wear behavior of corundum abra- sives were investigated. When the number of additive phases increases, the sintering temperature and wear rate decrease, while the densification and mechanical properties increase. The additive SiO2 is responsible for the development of equiaxed grains, whereas both CaO and MgO promote the development of platelike grains. By controlling the molar ratio of additives, it is pos- sible to obtain different microstructures. With SiO2-MgO-CaO （molar ratio, 2：1：1） as the additives and nano a-Al203 powders as the seed, microcrystalline corundum abrasives with hexagonal platelets were obtained using sol-gel process by sintering at 1300℃ for 0.5 h. The average diameter and thickness of hexagonal platelets are 1.38 μm and 360 nm respectively, the sin- gle-particle compressive strength is 26.44 N, and the wear rate is （3.06±=0.21）× 10^-7 mm^3/（N.m）.

Profile of biological characterizations and clinical application of corneal stem/progenitor cells

Corneal stem/progenitor cells are typical adult stem/progenitor cells.The human cornea covers the front of the eyeball,which protects the eye from the outside environment while allowing vision.The location and function demand the cornea to maintain its transparency and to continuously renew its epithelial surface by replacing injured or aged cells through a rapid turnover process in which corneal stem/progenitor cells play an important role.Corneal stem/progenitor cells include mainly corneal epithelial stem cells,corneal endothelial cell progenitors and corneal stromal stem cells.Since the discovery of corneal epithelial stem cells(also known as limbal stem cells)in 1971,an increasing number of markers for corneal stem/progenitor cells have been proposed,but there is no consensus regarding the definitive markers for them.Therefore,the identification,isolation and cultivation of these cells remain challenging without a unified approach.In this review,we systematically introduce the profile of biological characterizations,such as anatomy,characteristics,isolation,cultivation and molecular markers,and clinical applications of the three categories of corneal stem/progenitor cells.

Discovery of Shaanxilithes from the Dengying Formation in the Yangtze Gorges area, South China, and its stratigraphic significance

1.Objectives Shaanxilithes is one of the potential biostratigraphic markers for the definition and correlation of terminal Ediacaran strata.They have been found in terminal Ediacaran siliciclastic successions from Shaanxi Province(Meyer M et al.,2012),Ningxia Hui Autonomous Region(Shen B et al.,2007),Qinghai Province(Shen B et al.,2007),Guizhou Province(Hua H et al.,2004),Yunnan Province(Zhang ZL et al.,2015)in China,and India(Tarhan LG et al.,2014),Siberia(Cai YP and Hua H,2011)and Namibia(Darroch S et al.,2016).However,these fossils have never been found in the carbonate dominant Dengying Formation in the Yangtze Gorges area.

Clinical and genetic analysis of one late-onset family with Charcot–Marie–Tooth type 2A:Case report

Objective:To analyze the clinical and genetic characteristics of late-onset Charcot–Marie–Tooth(CMT)type 2A.Methods:A pedigree survey combined with clinical and genetic testing was used for integrated analyses.Results:The proband showed muscle atrophy in both hips and thighs,obviously in the posterior sides of both legs.The serum creatine kinase(CK)value was 272U/L.EMG:the median nerve conduction velocity was normal and the nerves of both lower extremities showed neurogenic damage(mainly axonal).Genetic testing revealed a heterozygous variant in exon 9 of the MFN2 gene NM 014874:c.839G>A(p.R280H).The Father of the proband had similar symptoms of peripheral neuromuscular and the same heterozygous mutation,but the mother did not show similar clinical symptoms and the genetic mutation.Conclusion:Pedigree investigation combined with clinical and genetic analysis is a kind of reliable method for late-onset CMT2A diagnosing and helping to identify different neuromuscular diseases.

Holographic superfluid ring with a weak link

We explore the generation of topological defects in the course of a dynamical phase transition in a ring with a weak link, i.e., a SSS Josephson junction, from the AdS/CFT correspondence. By setting different parameters of the junction(width, steepness,depth) and the final temperature of the quench, the configurations of the charge density and condensate of the order parameters of the dual field theory are presented. Meanwhile, we observe that in the final equilibrium state, variations in parameters of the junctions only affect the configurations of the charge density and condensate of the order parameters, without altering their values outside the junction. However, variations in the final temperature will directly affect the values of the charge density and condensate of the order parameters outside of the junction. Moreover, in the final equilibrium state, we propose an analytic relation between the gauge-invariant velocity in the two superconducting states in the SSS Josephson junction, which agrees well with the numerical results.

Preparation of large-area isotopic magnesium targets for the 25Mg(p,γ)^26 Al experiment at JUNA

To study the 25Mg(p,y)^26 Al reaction at the Jinping Underground Nuclear Astrophysics laboratory,a large-area 25Mg target with a uniform thickness is needed.A rotating unit is used to ensure the uniformity of the target thickness during evaporation.After many attempts,19 targets with diameters of 40 mm and a non-uniformity of8.4%were prepared simultaneously.The rate of material utilization was approximately 4.7 times higher than that obtained using a conventional evaporation method.

Response functions of a 4π summing gamma detector in β-Oslo method

The response functions of a 4π summing BGO detector were established using extensive experimental measurements and GEANT4 simulation. The partial and total efficiencies for all components of the γ-ray interaction with the BGO detector were also measured. These response functions and efficiencies will be used in the β-Oslo method experiments to study the neutron capture cross sections of radioactive heavy ions. The application of the response functions of the BGO detector under simulated continuum γ-rays and source measurement γ-rays proves that the method and response functions are reliable.

Ordovician sequence stratigraphy and correlation in the Middle-Upper Yangtze region,South China

The precise correlation of the Ordovician successions in different facies is difficult due to the complex changes of the tecto-paleogeography in South China.Based on previous studies,the authors recognized 103rd grade sequences,i.e.,Osq1 to Osq10 in ascending order,by the integrated study of chronostratigraphy,biostratigraphy as well as the analysis on the sedimentary facies.The authors are confident to correlate the Ordovician successions precisely in different facies in an isochronous stratigraphic framework with the application of the method of sequence stratigraphy and correlation.

Epigenetic regulation in metabolic diseases:mechanisms and advances in clinical study

Epigenetics regulates gene expression and has been confirmed to play a critical role in a variety of metabolic diseases,such as diabetes,obesity,non-alcoholic fatty liver disease(NAFLD),osteoporosis,gout,hyperthyroidism,hypothyroidism and others.The term‘epigenetics’was firstly proposed in 1942 and with the development of technologies,the exploration of epigenetics has made great progresses.There are four main epigenetic mechanisms,including DNA methylation,histone modification,chromatin remodelling,and noncoding RNA(ncRNA),which exert different effects on metabolic diseases.Genetic and non-genetic factors,including ageing,diet,and exercise,interact with epigenetics and jointly affect the formation of a phenotype.Understanding epigenetics could be applied to diagnosing and treating metabolic diseases in the clinic,including epigenetic biomarkers,epigenetic drugs,and epigenetic editing.In this review,we introduce the brief history of epigenetics as well as the milestone events since the proposal of the term‘epigenetics’.Moreover,we summarise the research methods of epigenetics and introduce four main general mechanisms of epigenetic modulation.Furthermore,we summarise epigenetic mechanisms in metabolic diseases and introduce the interaction between epigenetics and genetic or non-genetic factors.Finally,we introduce the clinical trials and applications of epigenetics in metabolic diseases.

基于伏邪理论探讨幽门螺旋杆菌感染

幽门螺旋杆菌是临床常见感染之一。本文通过梳理古今伏邪相关理论,并将伏邪理论与现代感染病学知识进行联系,得出伏邪与幽门螺旋杆菌都具有潜伏性、消耗性、复发性等特性;伏邪的发病和幽门螺旋杆菌的感染都与机体正邪状态相关;伏邪“直中”胃腑与幽门螺旋杆菌经消化道感染的发病方式相类似等结论。探讨幽门螺旋杆菌与伏邪的关系可为中医学深入认识及防治幽门螺旋杆菌相关性疾病提供新的诊疗思路。

2013年云南丽江拉市海鹤类及大型水禽的数量及栖息地

2013年1月17—18日,在云南拉市海高原湿地自然保护区镇美泉河、海东、海南、均良、格乐5个分界明确的观察区域,运用10×42的双筒望远镜,于上午08:00—10:00对各自区域内的鹤类和大型水禽进行同步直接计数并汇总。结果表明:灰鹤(Grus grus)、斑头雁(Anser indicus)和赤麻鸭(Todorna ferruginea)的数量分别是378、1176和662只,未观察到黑颈鹤。栖息地中,农田占86%,草地占6%,浅水区和休耕地各占3%,泥滩沼泽区占2%。

The current and future potential geographic range of West Indian fruit fly, Anastrepha obliqua （Diptera： Tephritidae）

The West Indian fruit fly, Anastrepha obliqua （Macquart）, is one of the most important pests throughout the Americas. CLIMEX 3.0 and ArcGIS 9.3 were used to model the current and future potential geographical distribution of this pest. Under current climatic conditions, A. obliqua is predicted to be able to establish throughout much of the tropics and subtropics, including not only North and South America, where it has been reported, but also southern Asia, northeastern Australia and Sub-Saharan Africa. The main factors limiting the pest＇s range expansion may be cold stress. Climate change expands the potential distribution of A. obliqua poleward as cold stress boundaries recede, but the predicted distribution in northwestern Australia and northern parts of Sub-Saharan Africa will decrease because of heat stress. Considering the widely suitable range for A. obliqua globally and in China, enhanced quarantine and monitoring measures should be implemented in areas that are projected to be suitable for the establishment of the pest under current and future climatic conditions.

Diversity of bacteria in different life stages and their impact on the development and reproduction of Zeugodacus tau(Diptera:Tephritidae)

Fruit flies usually harbor diverse communities of bacteria in their digestive systems,which are known to play a significant role in their fitness.However,little information is available on Zeugodacus tau,a polyphagous pest worldwide.This study reports the first extensive analysis of bacterial communities in different life stages and their effect on the development and reproduction of laboratory-reared Z tan.Cultured bacteria were identified using the conventional method and all bacteria were identified by highthroughput technologies(16S ribosomal RNA gene sequencing of V3-V4 region).A total of six bacterial phyla were identified in larvae,pupae,and male and female adult flies,which were distributed into 14 classes,32 orders,58 families and 96 genera.Proteobacteria was the most represented phylum in all the stages except larvae.Enterobacter,Klebsiella,Providencia,and Pseudomonas were identified by conventional and next-generation sequencing analysis in both male and female adult flies,and Enterobacter was found to be the main genus.After being fed with antibiotics from the first instar larvae,bacterial diversity changed markedly in the adult stage.Untreated flies laid eggs and needed 20 days before oviposition while the treated flies showed ovary development inhibited and were not able to lay eggs,probably due to the alteration of the microbiota.These findings provide the cornerstone for unexplored research on bacterial function in Z tau,which will help to develop an environmentally friendly management technique for this kind of harmful insect.

New determination of the^7Be ground state spectroscopic factor and the^6Li(p,γ)^7Be astrophysical S(E)factors

The ＇lithium problem, in Big Bang nucleosynthesis（BBN） has recently focused on reactions involving ^7 Be.The ^6 Li（p,γ）^7 Be reaction can provide us not only with information about ^6 Li destruction but also with information about ^7 Be production. In the present work, the proton spectroscopic factor in ^7 Be is extracted to be 0.70 ± 0.17 from the angular distribution of ^7 Be（d, ^3 He）^6 Li at Ec.m. = 6.7 MeV. This value is then used to compute the direct component of the astrophysical ^6 Li（p,γ）^7 Beg.s. S（E） factors and determine the resonance parameters from the total S（E） factors.

Cross-section prediction for isotopes near neutron drip line in 70, 80Zn projectile fragmentation reactions

The cross sections for 59,60Ca, recently measured in the 345 A MeV 70Zn+9 Be reaction,were estimated using the FRACS parametrization and an empirical formula,which are in good agreement.The FRACS parametrization and the empirical formula are combined to predict the cross sections for extreme calcium isotopes 66,70Ca in the70,80Zn+9 Be reactions at the incident energies of 60,80,and 345 A MeV.The dependence of emperical formula parameters on the reaction system,as well as the incident energy,are discussed.The results indicate that 66,70Ca can be discovered in reactions of 60,80A MeV 80Zn+9 Be.The predicted binding energy for extreme neutron-rich isotopes by the spherical relativistic continuum Hartree-Bogoliubov theory was adopted in the calculation.Hence,the planned Beijing Isotope-Separation-On Line Neutron-Rich Beam Facility(BISOL),which is a third generation radioactive ion beam facility,could provide the opportunity to discover 66,70 Ca and neighboring neutron-drip line nuclei.

Measurement of the^2H(^7Be,^6Li)^3He reaction rate and its contribution to the primordial lithium abundance

In the standard Big Bang nucleosynthesis （SBBN） model, the lithium puzzle has attracted intense interest over the past few decades, but still has not been solved. Conventionally, the approach is to include more reactions flowing into or out of lithium, and study the potential effects of those reactions which were not previously considered. 7Be（d, 3He）6Li is a reaction that not only produces 6Li but also destroys 7Be, which decays to 7Li, thereby affecting 7Li indirectly. Therefore, this reaction could alleviate the lithium discrepancy if its reaction rate is sufficiently high. However, there is not much information available about the 7Be（d, 3He）6Li reaction rate. In this work, the angular distributions of the 7Be（d, 3He）6Li reaction are measured at the center of mass energies Ecm=4.0 MeV and 6.7 MeV with secondary 7Be beams for the first time. The excitation function of the 7Be（d, 3He）6Li reaction is first calculated with the computer code TALYS and then normalized to the experimental data, then its reaction rate is deduced. A SBBN network calculation is performed to investigate its influence on the 6Li and 7Li abundances. The results show that the 7Be（d, 3He）6Li reaction has a minimal effect on 6Li and 7Li because of its small reaction rate. Therefore, the 7Be（d, 3He）6Li reaction is ruled out by this experiment as a means of alleviating the lithium discrepancy.