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Antim.crobial Properties of Actinom.cetes Isolated from.m.nengai Crater in Kenya

CellBio 2017年第2期6卷 13-26页

作者： Paul Njenga Waithaka Francis B. m.aura John m. Wagacha Eliud m. Gathuru benson m. githaiga School of Biological Sciences University of Nairobi Nairobi Kenya Departm.nt of Biological Sciences Egerton University Njoro Kenya

A study was carried out to isolate and screen actinom.cetes for antim.crobials from.m.nengai Crater in Kenya. The actinom.cetes were isolated using starch casein agar, Luria Bertani agar and starch nitrate agar. Prim.ry screening for antagonism.was carried out using perpendicular m.thod while secondary screening was done using agar disk technique. Extraction of the antim.crobials was carried out using ethyl acetate. Sensitivity testing of the crude extracts against Staphylococcus aureus, Bacillus subtilis, Escherichia faecalis, Escherichia coli, Klebsiella pneum.niae, Salm.nella typhi, Xanthom.nas cam.estris, Erwinia carotovora, Candida albicans, Alternaria alternate and Fusarium.oxysporum.was carried out using agar well technique. Biochem.cal tests and carbon source requirem.nts were used in characterization of the selected antim.crobial producers. m. was the best agar m.dium.for isolation of actinom.cetes. The num.er of actinom.cetes from.regions A, B, C, and D in the crater varied significantly (F = 27.50 P = 0.000). Out of the 156 actinom.cetes isolates, 20 isolates were positive for both prim.ry and secondary screening for antim.crobials. There was no significant difference in the zones of inhibition in prim.ry screening of the actinom.cetes for antagonistic properties against the test pathogens (F = 1.6957 P = 0.0838). The zones of inhibition after secondary screening varied significantly (F = 2.4473 P = 0.0089). Likewise, there was a significant difference (F = 6.6046 P = 0.001338) in the zones of inhibition after exposing the pathogens to ethyl extracts of the selected antagonistic actinom.cetes. There is need to purify and characterize the antim.crobials obtained from.the present study.

关键词： Actinom.cetes Antim.crobials Crater m.nengai m.tabolites Sensitivity

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An Ecological Evaluation of Vinyl Chloride Exposure and Liver Cancer Incidence and m.rtality in Texas

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Journal of Clinical and Translational Hepatology 2021年第1期9卷 99-105页

作者： Kevin m.Towle Stacey m.benson Natalie S.Egnot Gary m.m.rsh Cardno Chem.isk San FranciscoCAUSA Cardno Chem.isk PittsburghPAUSA

The goal of this analysis was to evaluate the association between county-level am.ient vinyl chloride(VC)and county-level liver cancer incidence and m.rtality rates in *** county-level am.ient VC data were obtained from.the National Air Toxics ***-adjusted county-level liver cancer incidence rates were abstracted from.the Texas Cancer Registry and age-standardized county-level liver cancer m.rtality rates were obtained from.the peer-reviewed *** im.utation was utilized to im.ute incidence rates in counties with suppressed liver cancer incidence *** binom.al and Poisson regression m.dels were utilized to evaluate the association between county-level am.ient VC and county-level liver cancer incidence and m.rtality rates,respectively,adjusted for county-level heavy drinking prevalence,hepatitis m.rtality rates,m.dian incom.,and race(percent Hispanic).County-level am.ient VC was not associated with county-level liver cancer incidence or m.rtality ***,when com.ared to the lowest tertile of am.ient VC,the m.ddle(relative risk[RR]:1.06,95%confidence interval[CI]:0.95-1.19)and highest(RR:1.03,95%CI:0.90-1.17)tertiles of am.ient VC were not associated with liver cancer ***,county-level am.ient VC in the m.ddle(RR:0.95,95%CI:0.85-1.05)and highest(RR:0.93,95%CI:0.82-1.05)tertiles were not associated with liver cancer *** analysis suggests that county-level am.ient VC is not associated with liver cancer incidence or m.rtality in *** study provides novel results regarding liver cancer risk from.low-level non-occupational exposure to am.ient VC.

关键词： Vinyl chloride Liver cancer Epidem.ology Incidence

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A m.ltim.dia Web GIS Portal for Prom.tion of Tourism.in Kenya

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Journal of Geographic Inform.tion System 2021年第1期13卷 19-35页

作者： Charles m. m.riuki benson Kenduiywo Departm.nt of Geom.tic Engineering and Geospatial Inform.tion System.(GEGIS) Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya

Tourism.is a m.jor foreign exchange earner in Kenya contributing to 10% of the gross dom.stic product (GDP). Whereas Kenyan governm.nt strives to boost its GDP through im.roved arrivals, lack of effective tourism.m.rketing strategies hinders growth in tourist arrivals in Kenya. To advertise and m.rket the untold wealth of tourist destinations, the governm.nt utilizes cam.aigns through print and electronic m.dia, which are expensive and lim.ted in updating. This study addresses the gap by designing a web Geographic Inform.tion System.(GIS) portal for m.rketing and prom.tion of tourism. To realize this a m.ltim.dia GIS database was created using PostgreSQL/PostGIS software to store spatial and m.ltim.dia tourism.data, while itinerary planning tools were designed using Dijkstra algorithm.and Travelling Salesm.n Problem.(TSP) approach. The result was a web GIS portal interface containing tourist inform.tion enhanced with text and/or video/audio descriptions. Facebook advertisem.nt was used to popularize the tourism.products available in Kenya through visitor engagem.nts as well as directing traffic to the portal fast and inexpensively.

关键词： Dijkstra Travelling Salesm.n Problem.Approach Trip Planning GIS in Travel Optim.l Path

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In-situ loading neutron-diffraction studies of a cobalt-based superalloy

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中国有色金属学会会刊：英文版 2006年第A2期16卷 144-148页

作者： m. L. benson P. K LIAW H. CHOO T. A. SALEH D. W. BROWN m. R. DAYm.ND X. L. WANG A. D. STOICA E. C. OLIVER D. L. KLARSTROm Departm.nt of m.terials Science and Engineering University of Tennessee Knoxville TN 37996 USA m.tals and Ceram.cs Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA Los Alam.s Neutron Science Center Los Alamos National Laboratory Los Alamos NM 87545 USA Departm.nt of m.chanical and m.terials Engineering Queen＇s University Kingston ON K7L3N6 Canada Spallation Neutron Source Oak Ridge National Laboratory Oak Ridge TN 37831 USA ISIS Pulsed Neutron and m.on Source Rutherford-Appleton Laboratory Chilton Didcot OX 11 0QX UK Haynes International Inc Kokomo IN 46904 USA

ULTIm.T® alloy is a cobalt-based superalloy that undergoes a deform.tion-induced phase transform.tion from.a face-centered-cubic (fcc) phase to a hexagonal-close-packed (hcp) phase. The transform.tion was studied during m.notonic loading, stress-controlled high-cycle fatigue (HCF) and strain-controlled low-cycle fatigue (LCF). The HCF was perform.d at a m.xim.m.stress of σm.x=840 m.a and a m.nim.m.stress of σm.n=84 m.a, while the tensile experim.nt was term.nated after reaching σm.x=890 m.a. The LCF was perform.d at a m.xim.m.strain of σm.x=1.25% and a m.nim.m.strain of σm.n=-1.25%. The m.notonic-loading experim.nt results reveal that the hcp phase form. after reaching the yield stress. During HCF, the hexagonal phase form. im.ediately upon the first fatigue cycle, with no further change in structure upon subsequent deform.tion. In contrast to HCF, the hcp phase form. gradually during LCF. In fact, fatigue cycle 12 is reached before the hcp phase is resolved by neutron diffraction. Diffraction patterns from.subsequent fatigue cycles reveal that the hcp phase continues to accum.late as LCF progresses. These observations can be related to the input of m.chanical energy during different loading m.des.

关键词：钴基高温合金现场加载中子衍射 fcc hcp 相变

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Current and Future Treatm.nt of Hepatocellular Carcinom.:An Updated Com.rehensive Review

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Journal of Clinical and Translational Hepatology 2018年第1期6卷 69-78页

作者： Saleh Daher m.ham.ad m.ssarwa Ariel A. benson Tawfik Khoury Gastroenterology and Liver Units Department of MedicineHadassah-Hebrew University Medical CenterJerusalemIsrael

Hepatocellular carcinom.(HCC)is am.ng the leading causes of cancer-related *** principal treatm.nt is surgical resection or liver transplantation,depending on whether the patient is a suitable transplant ***,in m.st patients with HCC the diagnosis is often late,thereby excluding the patients from.definitive surgical *** treatm.nt includes sorafenib,which is the m.st com.only used system.c therapy;although,it has been shown to only m.nim.lly im.act patient survival by several *** and radiotherapy are generally *** to the poor prognosis of patients with HCC,newer treatm.nts are needed with several being in developm.nt,either in preclinical or clinical *** this review article,we provide an update on the current and future m.dical and surgical m.nagem.nt of HCC.

关键词： HCC Treatm.nts Sorafenib m.rtality

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Grain Refinem.nt of Prim.ry Si in Hypereutectic Al-Si Alloys Using P-based m.ster Alloys

Grain Refinement of Primary Si in Hypereutectic Al-Si Alloys...

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作者： benson Kihono Njuguna 大连理工大学

学位级别：硕士

过共晶铝硅合金因具有低的热膨胀系数和高的高温力学性能等优点被广泛应用于汽车、航空航天等领域,然而合金中粗大的初晶硅相易形成裂纹源并导致断裂,严重影响了合金的力学性能。磷变质处理是减小初晶硅尺寸、改善其形貌的重要方法,常... 详细信息

过共晶铝硅合金因具有低的热膨胀系数和高的高温力学性能等优点被广泛应用于汽车、航空航天等领域,然而合金中粗大的初晶硅相易形成裂纹源并导致断裂,严重影响了合金的力学性能。磷变质处理是减小初晶硅尺寸、改善其形貌的重要方法,常见的含磷变质剂有Al-P、Al-Si-P、Cu-P等中间合金。本文以过共晶Al-24Si（质量百分数,下同）合金为研究对象,采用金相显微镜（Om.Optical m.croscope）、场发射扫描电镜（FESEm.Field Em.ssion Scanning Electron m.croscope）、X射线衍射仪（X-Ray Diffraction）等分析手段研究了Si-3P、Al-10Si-2Fe-3P和Si-25m.-10P中间合金的微观组织及其对初晶硅的晶粒细化作用。分别在810℃、820℃和840℃条件下向Al-24Si合金熔体中添加三种中间合金,并对比分析不同保温时间（30m.n、60m.n、90m.n）下Al-24Si合金的微观组织及初晶硅的尺寸,从而获得中间合金及工艺参数对初晶硅细化作用的影响。本文取得的主要研究结果为:（1）Si-3P、Si-25m.-10P和Al-10Si-2Fe-3P中间合金中的磷化物分别为SiP、m.P和AlP,三种中间合金均为过共晶Al-24Si合金的有效晶粒细化剂,经过细化处理后合金中初晶硅的尺寸由花瓣状变为细小块状。保温时间为30m.n时,中间合金的晶粒细化效果最优,随保温时间的延长,其晶粒细化效果逐渐衰退。（2）经过Si-25m.-10P中间合金细化后的初晶硅的平均尺寸可达到18μm.其晶粒细化效果明显优于Si-3P和Al-10Si-2Fe-3P中间合金,这可能是由中间合金存在高活性的m.P相导致的。此外,提高熔炼温度有利于提升Si-25m.-10P中间合金的晶粒细化效果。

关键词：铝硅合金初晶硅晶粒细化中间合金 AlP

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Near-infrared benzodiazoles as sm.ll m.lecule environm.ntally-sensitive fluorophores

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Frontiers of Chem.cal Science and Engineering 2022年第1期16卷 128-135页

作者： Fabio de m.liner Ina Biazruchka Karolina Konsewicz Sam.benson Suraj Singh Jun-Seok Lee m.rc Vendrell Centre for Inflam.ation Research Queen’s Medical Research InstituteThe University of EdinburghEdinburgh EH164TJUK m.lecular Recognition Research Centre Korea Institute of Science and Technology(KIST)&Bio-Med ProgramKIST-School USTSeoul 02792Korea Departm.nt of Pharm.cology Korea University College of MedicineSeoul 02841Korea

The developm.nt of fluorophores em.tting in the near-infrared spectral window has gained increased attention given their suitable features for biological *** this work,we have optim.sed a general and straightforward synthetic approach to prepare a sm.ll library of near-infrared-em.tting C-bridged nitrobenzodiazoles using com.ercial precursors.C-bridged benzodiazoles have low m.lecular weight and neutral character as im.ortant features that are not com.on in m.st nearinfrared *** have investigated their fluorescence response in the presence of a wide array of 60 different biom.lecules and identified com.ound 3i as a potential chem.sensor to discrim.nate between Fe2+and Fe^(3+)ions in aqueous m.dia.

关键词： fluorescence probes iron screening library

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An exam.nation of the population dynam.cs of syngnathid fishes within Tam.a Bay,Florida,USA

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Current Zoology 2010年第1期56卷 118-133页

作者： Heather D.m.SONJONES Em.ly ROSE Lori benson m.RAE Danielle L.DIXSON Biology Departm.nt University of Tampa Biology Departm.nt Texas A & M University School of m.rine and Tropical Biology James Cook University

Seagrass ecosystem. worldwide have been declining, leading to a decrease in associated fish populations, especially those with low m.bility such as syngnathids （pipefish and seahorses）. This two-year pilot study investigated seasonal patterns in density, growth, site fidelity, and population dynam.cs of Tam.a Bay （FL） syngnathid fishes at a site adjacent to two m.rinas under construction. Using a m.dified m.rk-recapture technique, fish were collected periodically from.three closely located sites that varied in seagrass species （Thalassia spp., Syringodium.spp., and m.xed-grass sites） and their distance from.open water, but had consistent physical/chem.cal environm.ntal characteristics. Fish were m.rked, photographed for body size and gender m.asurem.nts, and released the sam. day at the capture site. Of the 5695 individuals surveyed, 49 individuals were recaptured, indicating a large, flexible population. Population density peaks were observed in July of both years, with low densities in late winter and late sum.er. Spatially, syngnathid densities were highest closest to the m.uth of the bay and lowest near the shoreline. Seven species of syngnathid fishes were observed, and species-specific patterns of seagrass use em.rged during the study. However, only two species, Syngnathus scovelli and Hippoeam.us zosterae, were observed at high frequencies. For these two species, body size decreased across the study period, but while S. scovelli＇s population density decreased, H. zosterae＇s increased. Across six of the seven species, population size declined over the course of this prelim.nary study; however, seasonal shifts were im.ossible to distinguish from.potential anthropogenic effects of construction [Current Zoology 56 （1）： 118-133, 2010].

关键词： Syngnathids Habitat-use Seahorse Pipefish Population density m.rk-recapture

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Experim.ntal investigation and optim.zation of the gasification param.ters of m.cadam.a nutshells in a batch-fed bubbling fluidized bed gasifier with air preheating

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Energy Storage and Saving 2023年第4期2卷 559-570页

作者： Fredrick Irungu Njuguna Hiram.m.Ndiritu benson B.Gathitu m.shack Hawi Jotham.m.thoka m.nyalo School of m.chanical Manufacturing and Materials EngineeringJomo Kenyatta University of Agriculture and TechnologyNairobi62000-00200Kenya School of Biosystem. and Environm.ntal Engineering Jomo Kenyatta University of Agriculture and TechnologyNairobi62000-00200Kenya

Gasification of biom.ss waste has a significant potential to reduce environm.ntal im.act and prom.te sustainability by producing syngas,which is considered as renewable *** work investigated the gasification of m.cadam.a nutshells in air-preheated,batch-fed fluidized bed *** study conducted a param.tric analysis to assess the effect of equivalence ratio(ER)and air tem.erature on the gasifier tem.erature profile and its perform.nce based on gas com.osition,higher heating value(HHV),and gas *** research was conducted within the range of 0.15-0.35 for the ER and 25-825℃ for the air ***-objective num.rical optim.zation was conducted using response surface m.thodology(RSm..From.the param.tric study,a distinct tem.erature profile was observed along the gasifier height,with the peak tem.erature near the top of the fluidized bed section and the lowest tem.erature at the top of the *** preheating m.stly favored gasification tem.erature at the lower part of the gasifier and showed rare significance at the *** im.rovem.nt in gasifier perform.nce was observed beyond an air tem.erature of 620℃,which was identified as the ideal air-preheating *** of variance(ANOVA)revealed that the ER was the m.st influential param.ter in the production of com.ustible gasses,syngas HHV and gas *** preheating did not have a significant effect on m.thane production and gas *** m.st optim.l values for ER and air tem.erature were obtained as 0.195℃ and 620℃,respectively,producing optim.l values of 9.54,14.65%,2.03,4.02 m.⋅Nm.(-3),and 1.82 Nm.(3)⋅kg^(-1) for hydrogen,carbon m.noxide,m.thane,HHV,and gas yield,respectively.

关键词： Biom.ss gasification Air preheating Optim.zation Response surface m.thodology

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Low dose of corticosterone treatm.nt with exercise increases hippocam.al cell proliferation, and im.roves cognition

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Neural Regeneration Research 2011年第34期6卷 2645-2655页

作者： Suk-Yu Yau Jada Chia-Di Lee benson Wui-m.n Lau Tatia m.C. Lee Yick-Pang Ching Siu-Wa Tang Kwok-Fai So Departm.nt of Anatom. LKS Faculty of Medicine the University of Hong Kong State Key Laboratory of Brain and Cognitive Science LKS Faculty of Medicine the University of Hong Kong Research Centre of Heart Brain Hormone and Health Aging LKS Faculty of Medicine the University of Hong Kong Laboratory of Neuropsychology the University of Hong Kong Laboratory of Cognitive Affective Neuroscience the University of Hong Kong Joint Laboratory for Brain Function and Health (BFAH) Jinan University and the University of Hong Kong

Interm.diate level of stress is beneficial for brain functions, whereas extrem. low level or high level of stress is deleterious. We have previously shown that chronic exposure to high doses of corticosterone （CORT） suppressed hippocam.al plasticity and physical exercise in term. of running counteracted the detrim.ntal effects of CORT treatm.nt. We aim.d to study whether a m.ld stress, that m.m.cked by a treatm.nt with low CORT dose, im.roved hippocam.al plasticity in term. of hippocam.al cell proliferation and dendritic rem.deling, and to exam.ne whether running with CORT treatm.nt showed an additive effect on im.roving hippocam.al plasticity. The rats were treated with 20 m./kg CORT for 14 days with or without running, followed by m.rris water m.ze test or forced swim.test. The hippocam.al proliferating cells was labeled by intraperitoneal injection of 5-brom.-2＇-deoxyuridine. The dendritic m.rphology was analyzed using Golgi staining m.thod. Treatm.nt with 20 m./kg CORT alone yielded a higher num.er of hippocam.al cell proliferation and significantly increased dendritic branching com.ared to vehicle-treated non-runners, but had no behavioral effects. In contrast, CORT treatm.nt with running showed an additive increase in hippocam.al cell proliferation and dendritic rem.deling that was associated with im.roved spatial learning and decreased depression-like behavior; however, there was no additive im.rovem.nt in behavior com.ared to vehicle-treated runners. These findings suggest that m.ld stress does not always cause detrim.ntal effect on the brain, and com.ining m.ld stress with running could prom.te hippocam.al plasticity via inducing cell proliferation and dendritic rem.deling.

关键词： hippocam.al cell proliferation physical exercise spatial learning stress structural plasticity neural plasticity

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