检索结果-南通市图书馆

A new strategy for ionospheric remote sensing using the 130.4/135.6 nm airglow intensity ratios

维普期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2023年第4期7卷 445-459页

作者： XiaoHan Yin JianQi Qin larry J.Paxton School of Earth and Space Sciences Peking UniversityBeijing 100871China Applied Physics Laboratory Johns Hopkins UniversityLaurelMD 20723USA

We demonstrate here that global-scale determination of a key ionospheric parameter,the peak height of the F_(2)region(h_(m)F_(2)),can be obtained by making a simple ratio measurement of the atomic oxygen 130.4 and 135.6 nm emissions in the far-ultraviolet nightglow with a nadir-viewing system such as a pair of photometers suitable for flight on a CubeSat.We further demonstrate that measurements from an altitude that is within the typical range of nighttime h_(m)F_(2)250−450 km can provide the ratios that are needed for retrieval of the h_(m)F_(2).Our study is conducted mostly through numerical simulations by using radiative transfer models of the two emissions coupled with empirical models of the atmosphere and ionosphere.Modeling results show that the relationship between the h_(m)F_(2)and the intensity ratio is sensitive to the altitude from which the emissions are observed,primarily because of the distinctly different degrees of resonant scattering of the two emissions in the atmosphere.A roughly quadratic relationship can be established for observations from an orbit of~400 km,which enables h_(m)F_(2)retrieval.Parametric analysis indicates that the relationship can be affected by the ambient atmospheric conditions through resonant scattering and O2 absorption.For typical nighttime conditions with h_(m)F_(2)250−450 km,retrieval of the h_(m)F_(2)from synthetic observations shows that the typical errors are only a few kilometers(up to~20 km),depending on the accuracy of the ambient conditions predicted by the empirical models.Our findings pave the way for use of the 130.4/135.6 nm intensity ratios for global-scale monitoring of the nighttime ionosphere at mid to low latitudes.

关键词： nighttime ionosphere far-ultraviolet remote sensing 130.4/135.6 nm airglow intensity ratio peak height of the F_(2)region(h_(m)F_(2)) TiMED observation

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

高龄对男性生育力的影响

Asian Journal of Andrology 2013年第6期15卷 723-728,I0005页

作者： Jason R Kovac Josephine Addai Ryan P Smith Robert M Coward Dolores J Lamb larry i.lipshultz Scott Department of Urology Department of Molecular and Cellular Biology The Center for Reproductive Medicine Baylor College of Medicine Houston TX 77030 USA

在过去的几十年里，现代社会的压力和期望使得育龄夫妇生育年龄总体推迟。已知女性在临近40岁时卵母细胞的产生将会明显减少，而高龄对男性精子生成能力的影响还知之甚少。男性生育年龄无明确限制，因而高龄对男性生育能力的影响还不完... 详细信息

在过去的几十年里，现代社会的压力和期望使得育龄夫妇生育年龄总体推迟。已知女性在临近40岁时卵母细胞的产生将会明显减少，而高龄对男性精子生成能力的影响还知之甚少。男性生育年龄无明确限制，因而高龄对男性生育能力的影响还不完全清楚。本文将就目前已知的高龄对男性精子质量、生育能力和子代健康的影响进行综述，希望能在医生就男性推迟生育及高龄相关的风险咨询时起到一定的指导作用。

关键词：男性不育老年男性父亲年龄生育结局

Mechanistic insights into the Catalytic Condensation of Methyl Ketones on MgO Surfaces

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2023年第6期39卷 1010-1016页

作者： ZHOU Mingxia larry A.CURTiSS Rajeev S.ASSARY State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249P.R.China Materials Science Division Argonne National LaboratoryLemontIllinois 60439United States of America

Ketone coupling via aldol condensation is one of the promising routes to produce cyclic and value-added precursors for renewable hydrocarbon biofuels.A first-principles-based microkinetic modeling is performed to evaluate the surface-mediated reaction mechanisms and the role of water molecules in the observed activities for 2-pentanone and 3-pentanone aldol condensation on dehydroxylated MgO(111)surface and hydroxylated terminated surface[OH-MgO(111)].We have identified the enhancement of the surface OH group to MgO(111)surface catalytic activity by destabilizing the binding strength of reaction intermediates and reducing the energy barriers of rate-determining steps(proton transfer and dehydration steps).The 2-pentanone has one elementary step less in the complete reaction mechanism of aldol condensation and preferable energy barrier for proton transfer and dehydration steps,revealing 2-pentanone as terminal ketone is more reactive than 3-pentanone as central ketone.The water molecules dominated the OH-MgO(111)surface after further addition of water,leading to the reduction of turnover frequency of the aldol condensation dimer product as the loss of aldol condensation reaction intermediates in competitive adsorption with water molecules.

关键词： Aldol condensation Reaction mechanism Magnesium oxide Water effect Density functional theory

Seismic behavior assessment for design of integral abutment bridges in illinois

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2022年第2期21卷 573-589页

作者： Derek L.Kozak larry A.Fahnestock James M.LaFave KPFF Consulting Engineers inc 1601 Fifth AvenueSuite 1600SeattleWA 98101USA Dept.of Civil and Environmental Engineering Univ.of Illinois Urbana-ChampaignUrbanaIL 61801USA

integral abutment bridges(iABs)minimize deterioration and degradation of the abutment seats and bearings due to water,dirt,and deicing chemicals by eliminating bearings and expansion joints.Although the continuity between superstructure and abutments in an iAB is beneficial for reducing maintenance costs,it leads to more complex behavior under strength and service loading(temperature and traffic)and extreme loading(earthquake).The coupling of superstructure and substructure behavior necessitates system-level analysis of iABs.Prior seismic iAB studies have typically investigated the behavior of individual iAB components,however a gap of knowledge has developed due to the lack of studies and investigation about the behavior of all iAB components and their interactions with each other in a single analysis model.This study uses nonlinear static and dynamic analyses to investigate and assess the seismic behavior of iABs typical to the state of illinois.The analyses aim to bridge the gap of knowledge by evaluating iABs as a whole and utilizing the results to indicate potential vulnerabilities in the design and construction of iABs in illinois during design-level and larger seismic events,which could not be identified by component-level iAB analyses alone.

关键词： structural analysis seismic design bridge design structural models seismic analysis

Molecular evidence and phylogenetic delineation of spotted fever group Rickettsia species in Amblyomma ticks from cattle in Gauteng and Limpopo Provinces,South Africa

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2023年第8期16卷 371-378页

作者： Keneilwe Mhlambo Benson C iweriebor Nqobile Mkolo K O Afolabi larry C Obi Department of Biology and Environmental Sciences School of Science and TechnologySefako Makgatho Health Sciences UniversityGa-RankuwaPretoriaSouth Africa Pathogenic Yeasts Research Group Department of Microbiology and BiochemistryUniversity of the Free StateBloemfontein 9300Free StateSouth Africa School of Science and Technology Sefako Makgatho Health Sciences UniversityGa-RankuwaPretoriaSouth Africa

Objective:To determine the prevalence of tick-borne pathogens with a particular focus on Rickettsia spp.in ticks collected from cattle in Gauteng and Limpopo Provinces,South Africa.Methods:A total of 200 ticks were collected from cattle within the Madala livestock,Pretoria,Gauteng Province and in Mankweng Township,Polokwane,Limpopo Province in 2019.The ticks were morphologically identified and processed individually for a total genomic DNA extraction.Specific primers targetting ompA,ompB,and the 17KDa genes were used for a molecular screening and delineation of Rickettsia from the extracted genetic materials using polymerase chain reaction(PCR)technique.PCR amplicons of positive samples were sequenced bidirectionally using the Sanger sequencing method.Sequences generated were processed and analysed using appropriate bioinformatics software.Results:The ticks were morphologically identified as Amblyomma spp.PCR profiling of the genomic DNA samples revealed the presence of the Rickettsia pathogen in 42(21%)of the ticks collected from both Provinces.Out of the genes profiled,14(7%)were positive for 17KDa,42(21%)for ompA and 32(16%)were positive for ompB genes respectively.The nucleotide blast of the sequenced genomes showed high similarity,as high as 100% with other reference Rickettsia(R.)africae in the GenBank.The phylogenetic analysis of the sequences further validated them as R.africae with their characteristic clustering pattern with related reference sequences.Conclusions:There is an abundance of R.africae in Amblyomma ticks collected from cattle in the study areas.This has serious public health implications as individuals who accidentally get infested with the ticks could acquire R.africae.Hence,adequate precautions in terms of sensitization of farmers about the risk and mass mobilization drive to control the vectors in the areas are highly recommended to safeguard public health.

关键词： Amblyomma ticks Tick-borne pathogen Rickettsia Cattle South Africa

Antiproliferative effect of somatostatin analogs in gastroenteropancreatic neuroendocrine tumors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2010年第24期16卷 2963-2970页

作者： Jonathan Strosberg larry Kvols H. Lee Moffitt Cancer Center and Research institute

Somatostatin analogs were initially developed for the control of hormonal syndromes associated with neuro-endocrine tumors (NETs). in recent years, accumul ating data has supported their role as antiproliferative agents, capable of stabilizing tumor growth in patients with metastatic neuroendocrine malignancies, including carci-noid and pancreatic endocrine tumors. A phase Ⅲ, ran-domized, placebo-controlled trial has now demonstrated that octreotide long-acting repeatable (LAR) 30 mg can significantly prolong time to tumor progression among patients with metastatic midgut NETs regardless of functional status, chromogranin A level or age. in addition to signif icantly lengthening time to tumor pro-gression in the overall study population, subset analysis suggests that patients with low tumor burden are most likely to experience disease stabilization with octreotide LAR 30 mg, supporting the early use of octreotide LAR in patients with metastatic disease. Further research efforts are underway to evaluate the use of somatostatin analogs as antiproliferative agents in other types of gastroenteropancreatic-NETs. Ongoing studies are also evaluating novel somatostatin analogs and somatostatin analogs in combination with other anti-tumor therapies.

关键词： Somatostatin analogues Neuroendocrine tumors Antiproliferative

Advanced regeneration and fixed-bed study of ammonium and potassium removal from anaerobic digested wastewater by natural zeolite

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2013年第5期25卷 954-961页

作者： Xuejun Guo larry Zeng Xin Jin State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal University Environmental Technologies Alberta Research Council Inc.VegrevilleAlberta T9C 1T4Canada

Highly efficient regeneration of natural zeolite was developed in conjunction with the removal of high concentrations of ammonia and potassium from the reverse osmosis effluent of anaerobic-digested wastewater by fixed-bed ion exchange.The elution and uptake behavior of ammonium and potassium in the fixed bed were studied.Both batch desorption tests and on-column regeneration were conducted to develop an optimum regeneration condition compatible with the wastewater requirements.The effectiveness of ammonium elution increased with increasing alkaline concentration.The increase of salt dose significantly enhanced the ammonium maximum in the elution solution.Complete ammonium elution was achieved in 6 bed volumes（BV） when the alkaline and salt concentrations were respectively 0.1 mol/L and 18.6 g/L at a flow rate of 2.5-3.0 BV/hr.Due to the higher affinity of potassium with natural clinoptilolite,complete potassium elution was not achieved in all cases.

关键词： regeneration removal ammonium potassium natural zeolite

Epigenetic regulation in major depression and other stressrelated disorders: molecular mechanisms, clinical relevance and therapeutic potential

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2023年第9期8卷 4214-4243页

作者： Minlan Yuan Biao Yang Gerson Rothschild J.John Mann larry D.Sanford Xiangdong Tang Canhua Huang Chuang Wang Wei Zhang Mental Health Center and Psychiatric Laboratory the State Key Laboratory of BiotherapyWest China HospitalSichuan UniversityChengdu 610041China Department of Abdominal Oncology West China HospitalSichuan UniversityChengdu 610041China Department of Microbiology and immunology Vagelos College of Physicians and SurgeonsColumbia UniversityNew YorkNY 10032USA Department of Psychiatry Columbia UniversityNew YorkNY 10032USA Molecular imaging and Neuropathology Division New York State Psychiatric InstituteNew YorkNY 10032USA Department of Radiology Columbia UniversityNew YorkNY 10032USA Sleep Research Laboratory Center for Integrative Neuroscience and Inflammatory DiseasesPathology and AnatomyEastern Virginia Medical SchoolNorfolkVAUSA Sleep Medicine Center Department of Respiratory and Critical Care MedicineMental Health CenterTranslational Neuroscience Centerand State Key Laboratory of BiotherapyWest China HospitalSichuan UniversityChengdu 610041China Department of Biotherapy Cancer Center and State Key Laboratory of BiotherapyWest China HospitalSichuan UniversityChengdu 610041China Department of Pharmacology and Provincial Key Laboratory of Pathophysiology in School of MedicineNingbo UniversityNingboZhejiang 315211China West China Biomedical Big Data Center West China HospitalSichuan UniversityChengdu 610041China Medical Big Data Center Sichuan UniversityChengdu 610041China

Major depressive disorder(MDD)is a chronic,generally episodic and debilitating disease that affects an estimated 300 million people worldwide,but its pathogenesis is poorly understood.The heritability estimate of MDD is 30–40%,suggesting that genetics alone do not account for most of the risk of major depression.Another factor known to associate with MDD involves environmental stressors such as childhood adversity and recent life stress.Recent studies have emerged to show that the biological impact of environmental factors in MDD and other stress-related disorders is mediated by a variety of epigenetic modifications.These epigenetic modification alterations contribute to abnormal neuroendocrine responses,neuroplasticity impairment,neurotransmission and neuroglia dysfunction,which are involved in the pathophysiology of MDD.Furthermore,epigenetic marks have been associated with the diagnosis and treatment of MDD.The evaluation of epigenetic modifications holds promise for further understanding of the heterogeneous etiology and complex phenotypes of MDD,and may identify new therapeutic targets.Here,we review preclinical and clinical epigenetic findings,including DNA methylation,histone modification,noncoding RNA,RNA modification,and chromatin remodeling factor in MDD.in addition,we elaborate on the contribution of these epigenetic mechanisms to the pathological trait variability in depression and discuss how such mechanisms can be exploited for therapeutic purposes.

关键词： therapeutic clinical alterations

An infertile male with dilated seminal vesicles due to functional obstruction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2017年第2期19卷 256-257页

作者： Michael D Font Alexander W Pastuszak John R Case larry i Lipshult Baylor College of Medicine Houston TX 77030 USA Center for Reproductive Medicine Baylor College of Medicine Houston TX 77030 USA Scott Department of Urology Baylor College of Medicine Houston TX 77030 USA Urology San Antonio San Antonio TX 78229 USA

Dear Editor, The patient is a 45-year-old male who presented to an outside clinic in 2014 for evaluation of painful ejaculation, infertility, and difficulty with urination for as long as he could remember. He reported no past significant medical or surgical history and no family history of infertility. He was given a trial of tamsulosin without improvement in his symptoms. initial semen analysis demonstrated azoospermia.

关键词： infertile male dilated seminal vesicles due functional obstruction