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Piglet gut microbial shifts early in life:causes and effects 被引量:17
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作者 Robin B.Guevarra jun Hyung Lee +6 位作者 Sun Hee Lee Min-jae Seok Doo Wan Kim Bit Na Kang Timothy j.johnson Richard E.Isaacson Hyeun Bum Kim 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2019年第3期519-528,共10页
The gut microbiome has long been known to play fundamentally important roles in the animal health and the well-being of its host. As such, the establishment and maintenance of a beneficial gut microbiota early in life... The gut microbiome has long been known to play fundamentally important roles in the animal health and the well-being of its host. As such, the establishment and maintenance of a beneficial gut microbiota early in life is crucial in pigs, since early gut colonizers are pivotal in the establishment of permanent microbial community structures affecting the health and growth performance of pigs later in life. Emphasizing this importance of early gut colonizers, it is critical to understand the factors impacting the establishment of the piglet gut microbiome at weaning. Factors include, among others, diet, in-feed antibiotics, probiotics and prebiotic administration. The impact of these factors on establishment of the gut microbiome of piglets at weaning includes effects on piglet gut microbial diversity, structure, and succession. In this review, we thoroughly reviewed the most recent findings on the piglet gut microbiome shifts as influenced by weaning, and how these microbiome changes brought about by various factors that have been shown to affect the development of microbiota in piglets. This review will provide a general overview of recent studies that can help to facilitate the design of new strategies to modulate the gut microbiome in order to enhance gastrointestinal health, growth performance and well-being of piglets. 展开更多
关键词 MICROBIAL diversity Next generation sequencing 16S rRNA Swine MICROBIOTA WEANING
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Density dependence and habitat preference shape seedling survival in a subtropical forest in central China 被引量:12
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作者 junmeng Lu Daniel j.johnson +3 位作者 Xiujuan Qiao Zhijun Lu Qinggang Wang Mingxi jiang 《Journal of Plant Ecology》 SCIE 2015年第6期568-577,共10页
Aims seedlings are vulnerable to many kinds of fatal abiotic and biotic agents,and examining the causes of seedling dynamics can help understand mechanisms of species coexistence.To disentangle the relative importance... Aims seedlings are vulnerable to many kinds of fatal abiotic and biotic agents,and examining the causes of seedling dynamics can help understand mechanisms of species coexistence.To disentangle the relative importance of neighborhood densities,habitat factors and phylogenetic relatedness on focal seedling survival,we monitored the survival of 5306 seedlings of 104 species>15 months.We address the following questions:(i)How do neighborhood densities,habitat variables and phylogenetic relatedness affect seedling survival?What is the relative importance of conspecific densities,habitat variables and phylogenetic relatedness to seedling survival?(ii)Does the importance of the neighborhood densities,habitat variables and phylogenetic relatedness vary among growth forms,leaf habits or dispersal modes?specially,does the conspecific negative density dependence inhibit tree and decidu-ous seedlings more compared with shrub and evergreen species?Does density dependence affect the wind and animal-dispersed species equally?Methods We established 135 census stations to monitor seedling dynamics in a 25-ha subtropical forest plot in central China.Conspecific and heterospecific seedling density in the 1-m2 seedling plot and adult basal area within a 20-m radius provided neighborhood density var-iables.mean elevation,convexity and aspect of every 5-×5-m grid with seedling plots were used to quantify habitat characteristics.We calculated the relative average phylodiversity between focal seed-ling and heterospecific neighbors to quantify the species related-ness in the neighborhood.Eight candidate generalized linear mixed models with binominal error distribution were used to compare the relative importance of these variables to seedling survival.akaike’s information criteria were used to identify the most parsimonious models.Important Findingsat the community level,both the neighborhood densities and phylogenetic relatedness were important to seedling survival.We found negative effects of increasing conspecific seedlings,which 展开更多
关键词 generalized linear mixed models negative density dependence niche partitioning phylodiversity seedling dynamics species coexistence
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The exploitation of epichloae endophytes for agricultural benefit 被引量:10
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作者 Linda j.johnson Anouck C.M.de Bonth +11 位作者 Lyn R.Briggs john R.Caradus Sarah C.Finch Damien j.Fleetwood Lester R.Fletcher David E.Hume Richard D.johnson Alison j.Popay Brian A.Tapper Wayne R.Simpson Christine R.Voisey Stuart D.Card 《Fungal Diversity》 SCIE 2013年第3期171-188,共18页
Epichloae endophytes of family Clavicipitaceae(comprising genera Epichloëand Neotyphodium)are fungal symbionts of Pooideae grasses.The associations formed,range from mutually beneficial to antagonistic and the na... Epichloae endophytes of family Clavicipitaceae(comprising genera Epichloëand Neotyphodium)are fungal symbionts of Pooideae grasses.The associations formed,range from mutually beneficial to antagonistic and the nature of this relationship is dependent upon the importance of vertical(via host seeds)versus horizontal(ascospore mediated)transmission of the fungus.These endophytes can enhance their hosts’survival through protection from abiotic and biotic stresses and can thus be utilized in an agricultural context.Animal-safe grass-endophyte associations that confer bio-protective properties for increased pasture persistence and productivity have been developed and commercialized.One of the crucial drivers underpinning the selection of epichloae strains for commercial development is endophyte derived bioactivity.The potential of next generation endophytes is determined by testing a number of attributes such as agronomic fitness,animal and food safety as well as compatibility with host plants of interest.Strategic research supports these activities by focusing on elucidating mechanisms of compatibility between host and fungal symbiont,as well as investigating other molecular drivers of symbiosis such as siderophore mediated iron-uptake,fungal signalling,fungal growth in host plants and fungal secondary metabolism.This review weaves together the different strands of multidisciplinary research aimed at ultimately exploiting epichloae endophytes for increased pasture performance. 展开更多
关键词 Epichloë NEOTYPHODIUM POOIDEAE SYMBIOSIS Secondary metabolite TOXICOLOGY
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Thrombogenicity of biodegradable metals
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作者 D.E.j.Anderson H.H.Le +4 位作者 H.Vu j.johnson j.E.Aslan j.Goldman M.T.Hinds 《Bioactive Materials》 SCIE CSCD 2024年第8期411-421,共11页
Biodegradable metals offer a promising means to ameliorate many of the long-term risks associated with vascular devices made of conventional biostable stent metals.While numerous biodegradable metal alloys have been d... Biodegradable metals offer a promising means to ameliorate many of the long-term risks associated with vascular devices made of conventional biostable stent metals.While numerous biodegradable metal alloys have been developed and characterized in animal models,knowledge of their blood reactivity and thrombogenicity remains unknown.Metal hemocompatibility is particularly valuable because current generation drug-eluting stents pose a significant long-term thrombosis risk.In this study,four pure metals,widely used as degradable base materials(Fe,Zn,Mg,and Mo),and three alloys commonly used in cardiovascular devices[NiTi,CoCr,and stainless steel(SS)]were evaluated.This work examined how each of these metals activate platelets,coagulation factors,and inflammation using in vitro hemocompatibility assays and a clinically relevant ex vivo non-human primate arteriovenous shunt model.Testing found that while all metals promoted a downstream activation of platelets and coagulation in flowing whole blood,platelet and fibrin attachment to Mg was markedly reduced.Additionally,Fe and Mo trended toward higher platelet attachment and contact pathway activation.Overall,the results suggest that Mg may delay clot initiation,but not eliminate clot formation,indicating the importance of understanding thrombosis in Mg alloys that are currently being developed for clinical use as biodegradable stents. 展开更多
关键词 Vascular stents Biodegradable metals THROMBOSIS Contact pathway PLATELETS
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柽柳叶蝉名录及中国新记录属种记述(同翅目:叶蝉科) 被引量:2
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作者 蔡平 陆庆光 +1 位作者 C.j.DeLoach j.johnson 《华东昆虫学报》 1999年第1期15-21,共7页
本文记述中美两国农业部合作研究项目(柽柳生物防治研究)中采自我国西北部以及前苏联土库曼地区柽柳上的叶蝉科昆虫,初步鉴定有24 种,隶属于7 亚科、13 属,其中含4 中国新记录属(环茎叶蝉属 Circulifer Za... 本文记述中美两国农业部合作研究项目(柽柳生物防治研究)中采自我国西北部以及前苏联土库曼地区柽柳上的叶蝉科昆虫,初步鉴定有24 种,隶属于7 亚科、13 属,其中含4 中国新记录属(环茎叶蝉属 Circulifer Zachvatkin,大片叶蝉属 Meg alopsius Em eljanov,点纹叶蝉属 Op sius Fieber 和柽柳叶蝉属 Tam aricella Zachvatkin)、6 中国新记录种〔点翅短头叶蝉 Batrachom orphus irroratus Lew is,菲氏二叉叶蝉 M acrostelesfieberi ( Edw ards ),米氏二室叶蝉 Balclutha m itjaevi Dlabola,离茎点纹叶蝉 Op siusd istantiatus Dlabola,异点纹叶蝉 O.dissim ilis Vilbaste 和并茎点纹叶蝉 O.tigrip es ( Lethierry )〕。 展开更多
关键词 叶蝉科 柽柳 记述 名录 茎叶 防治研究 柳叶 属种 新记录属 中国新记录种
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家禽氨基酸消化率测定的原则及存在的问题(上) 被引量:2
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作者 Raymond j.johnson 王若军 《国外畜牧科技》 1993年第2期21-24,共4页
前言“可利用率”(availability)这一概念现已被动物营养界普遍接受,并广泛应用于能量代谢之中。虽然现代离子交换色谱技术已能精确测出饲料中总氨基酸的含量,但由根据总氨基酸配制日粮向根据可利用氨基酸配制日粮的转变却进展缓慢。现... 前言“可利用率”(availability)这一概念现已被动物营养界普遍接受,并广泛应用于能量代谢之中。虽然现代离子交换色谱技术已能精确测出饲料中总氨基酸的含量,但由根据总氨基酸配制日粮向根据可利用氨基酸配制日粮的转变却进展缓慢。现在,确定可利用氨基酸的方法很多,有体内法和体外法两种。主要根据准确、灵敏和便于操作这三条原则确定。如果要求实用性,则必须能够测定饲料工业中使用的各种类型的饲料,还要考虑饲料或日粮中其他组分影响氨基酸可利用率的可能性。只有同时根据混合日粮总氨基酸含量和可利用氨基酸含量。 展开更多
关键词 家禽 氨基酸 消化率 测定
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炭纤维的压缩特性 被引量:1
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作者 M.G.Dobb D.j.johnson +2 位作者 C.R.Park 刘敏 王作明 《炭素技术》 CAS CSCD 1992年第3期17-22,共6页
本文采用单丝反弹测试及扫描电镜观察(SEM)的方法研究了聚丙烯腈(PAN)基和中间相沥青基(MP)炭纤维的压缩特性,PAN—CF与MP—CF相比具有更高的压缩强度。本文从两相结构观点分析讨论了一些PAN—CF的优异抗拉和抗压强度,其中一相是标准的... 本文采用单丝反弹测试及扫描电镜观察(SEM)的方法研究了聚丙烯腈(PAN)基和中间相沥青基(MP)炭纤维的压缩特性,PAN—CF与MP—CF相比具有更高的压缩强度。本文从两相结构观点分析讨论了一些PAN—CF的优异抗拉和抗压强度,其中一相是标准的层面结构,另一相是无序碳结构。分析认为,MP—CF抗压强度较低是由于其结构的高度有序性(石墨化)及其固有的片状结构。受压缩CF的SEM显微照片表明纤维断裂的类型取决于纤维的种类。从而提出了两种不同的形变机制,即对PAN—CF来说是与扭曲有关的多弯曲带的形成机制以及对大多数MP—CF来说是与传统的剪切破坏有关的单一弯曲带的形成机制。 展开更多
关键词 炭纤维 压缩 性能
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血液循环中的肿瘤DNA及其在肿瘤研究上的应用
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作者 钟声 杨明明 Philip j.johnson 《中国肺癌杂志》 CAS 2001年第2期112-115,共4页
关键词 血液循环 肿瘤DNA 分子生物学
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家禽氨基酸消化率测定的原则及存在的问题(下)
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作者 Raymond j.johnson 王若军 《国外畜牧科技》 1993年第3期18-21,共4页
5 改进的 Sibbald 技术Sibbald(1979)测定氨基酸消化率的原始方法,已经过 Rhone—Poulenc 动物营养研究所作了广泛验证和改进(Rhone—Poulenc,1989)。在改进程序中,首先将单体笼内盲肠切除的成年公鸡限饲48小时(其间仅饲喂50g/天葡萄糖)... 5 改进的 Sibbald 技术Sibbald(1979)测定氨基酸消化率的原始方法,已经过 Rhone—Poulenc 动物营养研究所作了广泛验证和改进(Rhone—Poulenc,1989)。在改进程序中,首先将单体笼内盲肠切除的成年公鸡限饲48小时(其间仅饲喂50g/天葡萄糖),其后直接强饲50g 待测谷物或用玉米淀粉稀释后的高蛋白补充料(使测试料蛋白含量为16%~18%)。以后的48小时内,每天收集排泄物3次,将3只或6只公鸡的排泄物混在一起冻干,并在测定氨基酸含量前粉碎筛分。而内源氨基酸量则是通过强饲50g 无蛋白日粮(玉米淀粉加葡萄糖),收集48小时排泄物测定的。 展开更多
关键词 家禽 氨基酸 消化率 测定
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Soil water content and nitrogen differentially correlate with multidimensional leaf traits of two temperate broadleaf species
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作者 Ming-Yue jin Daniel j.johnson +2 位作者 Guang-Ze jin Qing-Xi Guo Zhi-Li Liu 《Plant Diversity》 SCIE CAS CSCD 2023年第6期694-701,共8页
The variation and correlation of leaf economics and vein traits are crucial for predicting plant ecological strategies under different environmental changes.However,correlations between these two suites of traits and ... The variation and correlation of leaf economics and vein traits are crucial for predicting plant ecological strategies under different environmental changes.However,correlations between these two suites of traits and abiotic factors such as soil water and nitrogen content remain ambiguous.We measured leaf economics and vein traits as well as soil water and nitrogen content for two different shade-tolerant species(Betula platyphylla and Acer mono)in four mixed broadleaved-Korean pine(Pinus koraiensis)forests along a latitudinal gradient in Northeast China.We found that leaf economics traits and vein traits were decoupled in shade-intolerant species,Betula platphylla,but significantly coupled in a shadetolerant species,A.mono.We found stronger correlations among leaf traits in the shade tolerant species than in the shade intolerant species.Furthermore,leaf economic traits were positively correlated with the soil water gradient for both species,whereas vein traits were positively correlated with soil water gradient for the shade intolerant species but negatively correlated in the shade tolerant species.Although economic traits were positively correlated with soil nitrogen gradient in shade intolerant species but not correlated in shade tolerant species,vein traits were negatively correlated with soil nitrogen gradient in shade tolerant species but not correlated in shade intolerant species.Our study provides evidence for distinct correlations between leaf economics and vein traits and local abiotic factors of species differing in light demands.We recommend that the ecological significance of shade tolerance be considered for species when evaluating ecosystem functions and predicting plant responses to environmental changes. 展开更多
关键词 Leaf trait multidimensionality Economics traits Vein traits Soil water content Soil total nitrogen Shade tolerance
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Office-based facial plastics procedures:Neuromodulators
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作者 Andrew j.johnson David S.Chen 《World Journal of Otorhinolaryngology-Head and Neck Surgery》 CAS CSCD 2023年第3期220-226,共7页
Botulinum toxin is a potent neuromodulator commonly used for cosmetic applications in the clinic.In this article,we reviewed the various formulations of botulinum toxin type A commercially available in the United Stat... Botulinum toxin is a potent neuromodulator commonly used for cosmetic applications in the clinic.In this article,we reviewed the various formulations of botulinum toxin type A commercially available in the United States,as well as clinical pearls for preprocedural planning,common in-office injections,and management of complications. 展开更多
关键词 botulinum toxin facial plastics facial wrinkles
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Trees species’ dispersal mode and habitat heterogeneity shape negative density dependence in a temperate forest
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作者 Lishunan Yang Daniel j.johnson +5 位作者 Zhichun Yang Xiaochao Yang Qiulong Yin Ying Luo Zhanqing Hao Shihong jia 《Forest Ecosystems》 SCIE CSCD 2023年第5期589-596,共8页
Conspecific negative density dependence(CNDD)is a potentially important mechanism in maintaining species diversity.While previous evidence showed habitat heterogeneity and species’dispersal modes affect the strength ... Conspecific negative density dependence(CNDD)is a potentially important mechanism in maintaining species diversity.While previous evidence showed habitat heterogeneity and species’dispersal modes affect the strength of CNDD at early life stages of trees(e.g.,seedlings),it remains unclear how they affect the strength of CNDD at later life stages.We examined the degree of spatial aggregation between saplings and trees for species dispersed by wind and gravity in four topographic habitats within a 25-ha temperate forest dynamic plot in the Qinling Mountains of central China.We used the replicated spatial point pattern(RSPP)analysis and bivariate paircorrelation function(PCF)to detect the spatial distribution of saplings around trees at two scales,15 and 50 m,respectively.Although the signal was not apparent across the whole study region(or 25-ha),it is distinct on isolated areas with specific characteristics,suggesting that these characteristics could be important factors in CNDD.Further,we found that the gravity-dispersed tree species experienced CNDD across habitats,while for wind-dispersed species CNDD was found in gully,terrace and low-ridge habitats.Our study suggests that neglecting the habitat heterogeneity and dispersal mode can distort the signal of CNDD and community assembly in temperate forests. 展开更多
关键词 BIODIVERSITY Conspecific negative density dependence Dispersal Replicated point patterns Temperate forest Topographic habitat
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卡斯凯迪亚消减带的周期性的慢地震 被引量:1
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作者 M.M.Miller T.Melbourne +2 位作者 D.j.johnson W.Q.Sumner 张弘 《世界地震译丛》 2003年第2期87-88,共2页
汇聚边界连续的大地测量结果显示,深部瞬时蠕变事件可释放大量的应变能而不产生可测震动,因而这种地震被称之为慢震或寂静地震。因为最大地震产生于消减带,所以了解慢震在多大程度上降低罕见大地震释放的能量,对地震危险性的评估至关重... 汇聚边界连续的大地测量结果显示,深部瞬时蠕变事件可释放大量的应变能而不产生可测震动,因而这种地震被称之为慢震或寂静地震。因为最大地震产生于消减带,所以了解慢震在多大程度上降低罕见大地震释放的能量,对地震危险性的评估至关重要。下面我们提供的资料说明发生在卡斯凯迪亚慢震的周期性和目前正在发生的这样一个地震。 展开更多
关键词 卡斯凯迪亚消减带 慢地震 静地震 周期性
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1000万年前的突变让我们变胖
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作者 理书德·j·约翰逊(Richard j.johnson) 彼得·安德鲁斯(Peter Andrews) 康俊炎 《环球科学》 2015年第11期76-81,共6页
如今,肥胖症和糖尿病随处可见,这种稍显现代的疾病可能与古猿的基因突变有关——当时让我们的祖先熬过食物匮乏期的基因,现在却让我们发胖甚至患上糖尿病。
关键词 基因突变 糖尿病 肥胖症 祖先 古猿
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2013年美国畜产品市场预测
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作者 Rachel j.johnson 赵健楠 《山西饲料》 2013年第2期33-39,共7页
2012年美国大部地区干旱导致牧草、玉米及大豆等饲料原料减产,对美国的畜牧养殖也有很大的冲击,美国农业部统计前11个月的畜牧业市场情况,对2013年的畜禽市场进行了预测,得出的结论是2013年畜禽市场持续低迷。对我们国内的畜禽行情... 2012年美国大部地区干旱导致牧草、玉米及大豆等饲料原料减产,对美国的畜牧养殖也有很大的冲击,美国农业部统计前11个月的畜牧业市场情况,对2013年的畜禽市场进行了预测,得出的结论是2013年畜禽市场持续低迷。对我们国内的畜禽行情具有一定的借鉴作用,特翻译此文。 展开更多
关键词 美国农业部 市场预测 畜产品 饲料原料 畜牧养殖 市场情况 畜牧业 畜禽
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液体硅橡胶模具设计原则
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作者 Virgil j.johnson 杨钧 《橡胶参考资料》 2000年第1期32-34,共3页
热固性液体硅橡胶(LSR)材料注射模具的设计一般与热塑性塑料模具的设计相同,其中有几点重要区别。其一,LSR胶料的粘度一般较低,所以充模时间很短,甚至在注射压力较低时也是如此。为了避免卷入空气,保证模具良好的排气很关键。
关键词 液体硅橡胶 橡胶 模具设计
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THE STRUCTURES OF SOME MESOPHASE PITCH-BASED CARBON FIBRES
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作者 M.G.Dobb 郭红 D.j.johnson 《Journal of China Textile University(English Edition)》 EI CAS 1993年第4期1-8,共8页
The macro-and micro-structure of two groups(high modulus and high thermalconductivity)of MP-based carbon fibres were studied using X-ray diffraction,and both scanningand transmission electron microscopy.The dominant m... The macro-and micro-structure of two groups(high modulus and high thermalconductivity)of MP-based carbon fibres were studied using X-ray diffraction,and both scanningand transmission electron microscopy.The dominant macrostructure in cross section is of foldedpseudo-radial layers which have a tendency to form a quasi-uniform domain as the fibre modulusincreases.It is found that high thermal conductivity fibres have both missimg sector and circularcross sections(possessed predominantly by the high modulus fibre group).The microstructuralstudy indicates that apart from the fibre C700,which has a three-dimensional graphite structure,these two groups of carbon fibres all exhibit a turbostratic stacking order.Furthermore it is foundthat the turbostratic stacking thickness as determined from dark-field measurement is much largerthan the classical crystallite thickness L_c as measured from X-ray diffraction. 展开更多
关键词 MESOPHASE PITCH CARBON FIBRE macrostructur microstructurc
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International validation of the Chinese University Prognostic Index for staging of hepatocellular carcinoma: a joint United Kingdom and Hong Kong study 被引量:5
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作者 Stephen L.Chan Philip j.johnson +8 位作者 Frankie Mo Sarah Berhane Mabel Teng Anthony W.H.Chan Ming C.Poon Paul B.S.Lai Simon Yu Anthony T.C.Chan Winnie Yeo 《Chinese Journal of Cancer》 SCIE CAS CSCD 2014年第10期481-491,共11页
The outcome of hepatocellular carcinoma(HCC) patients significantly differs between western and eastern population centers. Our group previously developed and validated the Chinese University Prognostic Index(CUPI) fo... The outcome of hepatocellular carcinoma(HCC) patients significantly differs between western and eastern population centers. Our group previously developed and validated the Chinese University Prognostic Index(CUPI) for the prognostication of HCC among the Asian HCC patient population. In the current study, we aimed to validate the CUPI using an international cohort of patients with HCC and to compare the CUPI to two widely used staging systems, the Barcelona Clinic Liver Cancer(BCLC) classification and the Cancer of the Liver Italian Program(CLIP). To accomplish this goal, two cohorts of patients were enrolled in the United Kingdom(UK; n = 567; 2006-2011) and Hong Kong(HK; n = 517; 2007-2012). The baseline clinical data were recorded. The performances of the CUPI, BCLC, and CLIP were compared in terms of a concordance index(C-index) and were evaluated in subgroups of patients according to treatment intent. The results revealed that the median follow-up durations of the UK and HK cohorts were 27.9 and 29.8 months, respectively. The median overall survival of the UK and HK cohorts were 22.9 and 8.6 months, respectively. The CUPI stratified the patients in both cohorts into three risk subgroups corresponding to distinct outcomes. The median overall survival of the CUPI low-, intermediate-, and high-risk subgroups were 3.15, 1.24, and 0.29 years, respectively, in the UK cohort and were 2.07, 0.32, and 0.10 years, respectively, in the HK cohort. For the patients who underwent curative treatment, the prognostic performance did not differ between the three staging systems, and all were suboptimal. For those who underwent palliative treatment, the CUPI displayed the highest C-index, indicating that this staging system was the most informative for both cohorts. In conclusion, the CUPI is applicable to both western and eastern HCC patient populations. The performances of the three staging systems differed according to treatment intent, and the CUPI was demonstrated to be optimal for those undergoing palliative treatment. A 展开更多
关键词 香港 英国 预后 肝癌 验证 国际 大学 中国
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IMPORTANCE OF HYDROLOGY, SOIL AND VEGETATIONIN WETLAND RESEARCH 被引量:4
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作者 Elizabeth j.johnson Peter L.M.Veneman XING Baos-han 《湿地科学》 CSCD 2003年第2期128-135,共8页
Wetlands, one of the most productive systems in the biosphere are a unique ecosystem. They occur in landscapes that favor the ponding or slow runoff of surface water, discharge of ground water, or both. Wetlands are n... Wetlands, one of the most productive systems in the biosphere are a unique ecosystem. They occur in landscapes that favor the ponding or slow runoff of surface water, discharge of ground water, or both. Wetlands are not only important for maintaining plant and animal diversity, but also for balancing global carbon budget via sequestrating or releasing CO2 from/into atmosphere depending on their management. Therefore, it is imperative to understand how wetlands form and function, then we can better manage, utilize, and protect these unique ecosystems. Hydrie soils,hydrophytic vegetation, and wetland hydrology are the three main parameters of wetlands. These parameters are interrelated with each other which jointly influence the development and functions of wetland ecosystems. The objective of this paper was to report the current understanding of wetlands and provide future research directions. The paper will first focus on aspects of hydrology research in wetlands, and then shift to soil hydrosequence and wetland vegetation to better understand processes, structure, and function of wetlands, and conclude with some possible future research directions. 展开更多
关键词 hydric soils VEGETATION HYDROLOGY WETLANDS future research
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Effect of Direct-Fed Microbial Supplementation on Pathogenic <i>Escherichia coli</i>Fecal Shedding, Live Performance, and Carcass Characteristics in Feedlot Steers
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作者 Alex Thompson M. Alexandra Calle +8 位作者 Flavio R. Ribeiro Ansen R. Pond Wanda M. Kreikemeier Allen McDonald Edward G. johnson Matthew D. Edmonds Guy H. Loneragan Mindy M. Brashears Bradley j. johnson 《Open Journal of Animal Sciences》 2020年第4期683-705,共23页
Three experiments were conducted to evaluate direct-fed microbial (<strong>DFM</strong>) supplementation on live performance, carcass characteristics, and fecal shedding of <em>E. coli</em> in ... Three experiments were conducted to evaluate direct-fed microbial (<strong>DFM</strong>) supplementation on live performance, carcass characteristics, and fecal shedding of <em>E. coli</em> in feedlot steers. In Exp. 1, 400 steers (BW = 348 kg) were assigned to treatments: <strong>CON</strong> = lactose carrier only, <strong>BOV</strong> =<em> P. freudenreichii </em>(NP24) +<em> L. acidophilus</em> (NP51), <strong>BOVD</strong> = <em>P. freudenreichii</em> (NP24) +<em> L. acidophilus</em> (NP51), and <strong>COMB</strong> = BOV fed for the first 101 d on feed, followed by BOVD for the final 28 d prior to harvest. In Exp. 2 (n = 1800;BW = 354 kg) and Exp. 3 (n = 112;BW = 397 kg), steers were utilized in a randomized complete block design and assigned to DFM treatments using low dose and high dose, respectively. Fecal samples were collected prior to harvest and analyzed for <em>E. coli</em> serogroups. In Exp. 1, DFM reduced (P < 0.01) the concentration of<em> E. coli</em> O157. Prevalence of O157 was reduced by BOVD supplementation in Exp. 2 and 3 (P < 0.01 and P = 0.08, respectively), and concentration of <em>E. coli</em> O157 in positive samples was reduced in both experiments where enumeration was performed (P ≤ 0.02). Weighted mean differences across the three experiments were equal to a 33% reduction in the prevalence of E. coli O157:H7 in BOVD treated cattle. A significant reduction in prevalence of O26, O45, O103, and O121 was observed in Exp. 2 (P ≤ 0.03). These results indicate that high levels of <em>L. acidophilus</em> (NP51) may represent an effective pre-harvest food safety intervention to reduce fecal shedding of several <em>E. coli</em> serogroups. 展开更多
关键词 Beef Cattle Direct-Fed Microbial Escherichia coli O157 Lactobacillus acidophilus Pre-Harvest Intervention
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