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Phenotypic plasticity in the monoclonal marbled crayfish is associated with very low genetic diversity but pronounced epigenetic diversity
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作者 Günter Vogt 《Current Zoology》 SCIE CAS CSCD 2023年第4期426-441,共16页
Clonal organisms are particularly useful to investigate the contribution of epigenetics to phenotypic plasticity,because confounding effects of genetic variation are negligible.In the last decade,the apomictic parthen... Clonal organisms are particularly useful to investigate the contribution of epigenetics to phenotypic plasticity,because confounding effects of genetic variation are negligible.In the last decade,the apomictic parthenogenetic marbled crayfish,Procambarus virginalis,has been developed as a model to investigate the relationships between phenotypic plasticity and genetic and epigenetic diversity in detail.This crayfish originated about 30 years ago by autotriploidy from a single slough crayfish Procambarus fallax.As the result of human releases and active spreading,marbled crayfish has established numerous populations in very diverse habitats in 22 countries from the tropics to cold temperate regions.Studies in the laboratory and field revealed considerable plasticity in coloration,spination,morphometric parameters,growth,food preference,population structure,trophic position,and niche width.Illumina and PacBio whole-genome sequencing of marbled crayfish from representatives of 19 populations in Europe and Madagascar demonstrated extremely low genetic diversity within and among populations,indicating that the observed phenotypic diversity and ability to live in strikingly different environments are not due to adaptation by selection on genetic variation.In contrast,considerable differences were found between populations in the DNA methylation patterns of hundreds of genes,suggesting that the environmentally induced phenotypic plasticity is mediated by epigenetic mechanisms and corresponding changes in gene expression.Specific DNA methylation fingerprints persisted in local populations over successive years indicating the existence of epigenetic ecotypes,but there is presently no information as to whether these epigenetic signatures are transgenerationally inherited or established anew in each generation and whether the recorded phenotypic plasticity is adaptive or nonadaptive. 展开更多
关键词 DNA methylation environmental adaptation EPIGENETICS epigenetic ecotypes marbled crayfish phenotypic plasticity whole-genome sequencing
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Allele Frequency Distribution in PNLIP Promoter SNP Is Different between High-Marbled and Low-Marbled Japanese Black Beef Cattle
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作者 Youji Muramatsu Hideki Tanomura +2 位作者 Takeshi Ohta Hiroyuki Kose Takahisa Yamada 《Open Journal of Animal Sciences》 2016年第2期137-141,共5页
Marbling defined by the amount and distribution of intramuscular fat is regarded as an economically important trait of beef cattle in Japan. The pancreatic lipase gene (PNLIP) is located within the genomic region of a... Marbling defined by the amount and distribution of intramuscular fat is regarded as an economically important trait of beef cattle in Japan. The pancreatic lipase gene (PNLIP) is located within the genomic region of a bovine marbling quantitative trait locus. The rat homologue of PNLIP has been previously shown to be regarded as a possible candidate for the gene responsible for intramuscular fat content. These findings suggested that PNLIP was a positional and functional candidate for the marbling gene. In this study, we detected a single nucleotide polymorphism (SNP), g.37288470A > G, at 1917 bp upstream of the PNLIP transcription initiation site between Holstein steers and somatic nuclear-derived cloned steers from a Japanese Black sire with a very high estimated breeding value for marbling by sequencing analysis. Further, we found statistically significant difference in the allelic distribution of the SNP between 17 Japanese Black unrelated sires with extremely high predicted breeding values for marbling and 17 sires with extremely low ones (P = 0.0332). Our findings suggest that g.37288470A > G SNP in the promoter region of PNLIP might be associated with marbling by altering its gene expression, and be useful for effective marker-assisted selection to increase the levels of marbling in Japanese Black beef cattle. 展开更多
关键词 PNLIP Japanese Black Breed MARBLING Single Nucleotide Polymorphism
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Stress conditions extend maternal care and delay juvenile development in crayfish
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作者 Davinder Kaur Koushik Das +1 位作者 Jan Kubec Milos Buric 《Current Zoology》 2025年第1期25-32,共8页
Maternal care in crayfish has been extensively studied,but little is known of its response to environmental factors.We studied the duration of maternal care and its association with the juvenile development of marbled... Maternal care in crayfish has been extensively studied,but little is known of its response to environmental factors.We studied the duration of maternal care and its association with the juvenile development of marbled crayfish Procambarus virginalis in adverse environmental conditions.We exposed females with developmental stage 3 juveniles to environments of low water volume(LW)with food provided,low water volume with no feed(starvation)(LWS),and low water volume without feeding plus an intruder(red swamp crayfish male)(LWSI).A control group with standard water level/feed conditions was included for comparison.Groups were monitored for up to 90 days.The LWS group showed significantly prolonged maternal care(~65 days)as indicated by an extended attachment phase,delayed moulting of mothers(~53 days),and retarded juvenile development.In the LWSI group,conflict precluded extended maternal care.Low use of shelter and feeding was evident under all stress conditions.The results showed that crayfish females modify maternal care in accordance with conditions,providing a longer period of safety for offspring under adverse circumstances.It is possible that the expression of maternal pheromones can manipulate the developmental rate in juveniles,a topic for future research. 展开更多
关键词 COMMUNICATION development marbled crayfish Procambarus virginalis OFFSPRING red swamp crayfish Procambarus clarkii
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VIIRS夜光影像中农田火像素识别方法
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作者 曹汉瑞 王妍 +3 位作者 李熙 胡申森 邱实 魏英策 《武汉大学学报(信息科学版)》 北大核心 2025年第10期2072-2085,共14页
夜光遥感影像已被广泛应用于人类活动、社会经济等方面的研究。南部非洲的夜光影像上存在烧田产生的农田火像素,这些像素易与城镇灯光像素混淆,干扰了夜光影像在社会经济评估中的应用。以南部非洲的10个大陆国家为研究区域,基于国家极... 夜光遥感影像已被广泛应用于人类活动、社会经济等方面的研究。南部非洲的夜光影像上存在烧田产生的农田火像素,这些像素易与城镇灯光像素混淆,干扰了夜光影像在社会经济评估中的应用。以南部非洲的10个大陆国家为研究区域,基于国家极地轨道伙伴关系卫星(national polar-orbiting partnership,NPP)/可见光红外成像辐射仪(visible infrared imaging radiometer,VIIRS)数据生产的黑色大理石(Black Marble)产品,首先构建了夜光辐亮度时间序列的3个特征;然后采用随机森林分类方法将夜光影像中的像素分为农田火像素、稳定灯光像素和全黑像素;最后采用分层随机抽样,用时间序列夜光辐亮度数据、高分辨率卫星影像和地表覆盖数据对像素分类结果进行精度检验。结果表明,像素分类的总体精度为91.2%,平均生产者精度为91.9%,平均用户精度为91.0%,其中农田火像素分类的生产者精度和用户精度分别为86.4%和92.6%。所提方法可在后续应用中滤除Black Marble产品中的农田火像素,提升夜光影像对非洲社会经济的评估精度。 展开更多
关键词 夜光遥感 NPP/VIIRS Black Marble产品 南部非洲 农田火
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A preliminary study of dietary protein requirement of juvenile marbled flounder (Pseudopleuronectes yokohamae) 被引量:1
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作者 Jeong-Hyeon Cho Seunghyung Lee +4 位作者 Bong-Joo Lee Sang-Woo Hur Kang-Woong Kim Maeng-Hyun Son Dong-Jae Yoo 《Animal Nutrition》 SCIE CSCD 2021年第2期548-555,共8页
An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder.Five semi-purified test diets were formulated to contain different protein levels(CP)including 42.7%,4... An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder.Five semi-purified test diets were formulated to contain different protein levels(CP)including 42.7%,47.4%,53.3%,58.8%,and 64.5%(dry matter),named as CP42.7,CP47.4,CP53.3,CP58.8,and CP64.5,respectively.Five hundred and twenty-five juveniles(6.0±0.1 g)were randomly distributed into 15 tanks(300 L tanks),resulting in 35 fish per tank(n-3 tanks).Fish were fed the test diets 5 times per day until satiation.The CP58.8 resulted in the highest gain in weight and the best efficiency in feed utilization among the tested protein levels(P<0.05).Fish fed the CP58.8 diet showed significantly higher whole-body protein and lipid contents than the fish that were fed the other diets(P<0.05).Fish fed the CP53.3,CP58.8,and CP64.5 diets showed a significantly higher dorsal-muscle lipid content than the fish that were fed the CP42.7 and CP47.4 diets(P<0.05).The one-slope straight broken-line regression analysis on the results of the thermal growth coefficient and feed conversion ratio indicated that the estimated optimum dietary protein level was 58.8%.Taken together,it is suggested that the dietary protein level of 58.8%is optimal for better growth and high efficiency in feed utilization for the juvenile marbled flounder. 展开更多
关键词 marbled flounder Pseudopleuronectes yokohamae Protein requirement Growth performance Proximate composition
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Cyclic loading of marble:Correlating the attenuation of the electric and acoustic activities and highlighting criticality indices in terms of natural time
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作者 Dimos Triantis Ilias Stavrakas +1 位作者 Ermioni D.Pasiou Stavros K.Kourkoulis 《International Journal of Mining Science and Technology》 2025年第2期159-174,共16页
The attenuation of the acoustic activity in marble specimens under uniaxial compressive loadingunloading loops is quantified in juxtaposition to that of the electric activity.In parallel,the existence of"pre-fail... The attenuation of the acoustic activity in marble specimens under uniaxial compressive loadingunloading loops is quantified in juxtaposition to that of the electric activity.In parallel,the existence of"pre-failure indiceso"warning about entrance into a critical stage,that of impending fracture,is explored.The acoustic activity is quantified in terms of the normalized number of acoustic hits,their average rate of production and their cumulative energy,and,the cumulative counts and their average rate of change.The electric activity is studied in terms of the pressure stimulated currents and the electric charge released.The analysis revealed that the acoustic and electric activities are linearly correlated to each other,suggesting that they are different manifestations of the same damage mechanisms.In addition,Kaiser's effect,governing the acoustic activity,is found to govern,also,the electric activity.Moreover,it is concluded that entrance into the critical stage is safely predicted by means of a simple criterion,based on the evolution of the average rate of change of the normalized cumulative counts in the natural time domain.These predictions are almost identical with those of the criterion based on the "varianceo" and the "entropies" of the time series of acoustic events in this domain. 展开更多
关键词 Marble cyclic loading Acoustic emissions Kaiser's effect Pressure stimulated currents Criticality indices Natural time
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Renal tubular acidosis:Varied aetiologies and clinical presentations:Three case reports
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作者 Akhila Bhandarkar Anwitha Varmudy +1 位作者 Hiya Boro Sowrabha Bhat 《World Journal of Nephrology》 2025年第2期168-177,共10页
BACKGROUND Renal tubular acidosis(RTA)refers to a group of kidney disorders characterized by defective acid excretion or bicarbonate reabsorption,leading to metabolic acidosis.This case series presents three cases of ... BACKGROUND Renal tubular acidosis(RTA)refers to a group of kidney disorders characterized by defective acid excretion or bicarbonate reabsorption,leading to metabolic acidosis.This case series presents three cases of RTA with distinct etiologies and clinical manifestations.These cases emphasize the necessity of a comprehensive evaluation of RTA,considering both renal and systemic origins.CASE SUMMARY The first case describes a female patient with osteopetrosis-related RTA,diagnosed with Guibaud-Vainsel syndrome,emphasizing the importance of genetic assessment.The second case delineates RTA secondary to focal segmental glomerulosclerosis,associating tubular dysfunction with glomerular pathology.In the first two cases whole exome sequencing confirmed genetic diagnosis.The third case illuminates RTA as a complication of Graves’disease,highlighting autoimmune implications.CONCLUSION These cases underscore the interdisciplinary approach essential in RTA management.Understanding the diverse pathophysiology of RTA aids in tailored therapeutic strategies and improved patient outcomes. 展开更多
关键词 Renal tubular acidosis Guibaud-Vainsel syndrome Marble brain disease OSTEOPETROSIS Focal segmental glomerulosclerosis Graves’disease Case series Case report
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Trace Element Mobility in Subducted Marble and Associated Eclogite:Constraints from UHP Rocks in the Shuanghe Area,Central-East China
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作者 Xingao Hou Zhiqiang Yu +2 位作者 Shefa Chen Lei Liu Yilin Xiao 《Journal of Earth Science》 SCIE CAS CSCD 2024年第1期1-15,共15页
In order to decipher element mobility in UHP meta-sedimentary rocks in the continental subduction zone,major and trace element compositions are investigated for a continuous profile from a representative UHP region in... In order to decipher element mobility in UHP meta-sedimentary rocks in the continental subduction zone,major and trace element compositions are investigated for a continuous profile from a representative UHP region in the Dabie Mountains.Among the lithologic contact zone,contents of K,Ca,LREE,and LILE exhibit varying degrees of downward trends in both marble and eclogite toward the contact zone,indicating that marble and their associated eclogite can release a large amount of K,Ca,and a small number of LILEs and LREEs.Titanite is the main Ti phase in both marble and eclogite.Titanite rims around rutile can occasionally be seen in eclogite.Contents of Ti and HFSE exhibit a well-coupled relation among marble and eclogite,indicating that substantial Ti and HFSEs were migrated from eclogite to marble,in accord with the capacity of a melt medium.Rutiles and titanites in marble exhibit a relatively limited variation in Nb/Ta ratios(12.9-16.2),similar to those of titanites in eclogite(14.2-16.7),which demonstrates that rutiles and titanites in marble were sourced from eclogite because of short-distance migrations of Ti and HFSEs.According to the P-T path and the temperature and pressure conditions of the peak metamorphism reported by previous studies,the eclogite associated with marble may not form supercritical fluids in the subduction zone because of the addition of carbonate minerals. 展开更多
关键词 UHP metamorphism ECLOGITE MARBLE element migration fluid actions geochemistry
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Evolution mechanism and quantitative characterization of initial micro-cracks in marble under triaxial compression
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作者 Zhiliang WANG Songyu LI +4 位作者 Jianguo WANG Ao LI Weixiang WANG Chenchen FENG Jingjing FU 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2024年第7期586-595,共10页
The initial micro-cracks affect the evolution characteristics of macroscopic deformation and failure of rock but are often ignored in theoretical calculation,numerical simulation,and mechanical experiments.In this stu... The initial micro-cracks affect the evolution characteristics of macroscopic deformation and failure of rock but are often ignored in theoretical calculation,numerical simulation,and mechanical experiments.In this study,we propose a quantitative analysis model to investigate the effects of initial micro-cracks on the evolution of marble deformation and failure.The relationship between the micro-crack propagation and the marble failure characteristics was comprehensively studied by combining theoretical analysis with a micro-computed tomography(micro-CT)scanning technique.We found that with the increase of confining pressure,the matrix elastic modulus of the marble first increased and then tended to be stable,while the micro-cracks increased exponentially.The sensitivity ranges of the marble sample matrix elastic modulus and micro-cracks to confining pressure were 0–30 MPa and 30–50 MPa,respectively.The porosity and Poisson’s ratio decreased exponentially.The increasing proportion of internal micro-cracks led to an increase in the sample non-uniformity.The samples presented mainly shear failure under triaxial compression,and the failure angle decreased linearly with the increase of confining pressure.The convergence direction of cracks decreased gradually.This quantitative analysis model could accurately portray the relationship between the overall macroscopic deformation and the deviatoric stress of the samples at the compaction and the linear elastic stages,thus deepening the understanding of the stress–strain behavior of rocks. 展开更多
关键词 MARBLE Initial micro-cracks Triaxial compression Constitutive relationship Crack evolution
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Mechanical response and dilatancy characteristics of deep marble under different stress paths:A sight from energy dissipation
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作者 LIU Xiao-hui HAO Qi-jun +2 位作者 ZHENG Yu ZHANG Zhao-peng XUE Yang 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期2070-2086,共17页
Dilatancy is a fundamental volumetric growth behavior observed during loading and serves as a key index to comprehending the intricate nonlinear behavior and constitutive equation structure of rock.This study focuses ... Dilatancy is a fundamental volumetric growth behavior observed during loading and serves as a key index to comprehending the intricate nonlinear behavior and constitutive equation structure of rock.This study focuses on Jinping marble obtained from the Jinping Underground Laboratory in China at a depth of 2400 m.Various uniaxial and triaxial tests at different strain rates,along with constant confining pressure tests and reduced confining pressure tests under different confining pressures were conducted to analyze the mechanical response and dilatancy characteristics of the marble under four stress paths.Subsequently,a new empirical dilatancy coefficient is proposed based on the energy dissipation method.The results show that brittle failure characteristics of marble under uniaxial compression are more obvious with the strain rate increasing,and plastic failure characteristics of marble under triaxial compression are gradually strengthened.Furthermore,compared to the constant confining pressure,the volume expansion is relatively lower under unloading condition.The energy dissipation is closely linked to the process of dilatancy,with a rapid increase of dissipated energy coinciding with the beginning of dilatancy.A new empirical dilatancy coefficient is defined according to the change trend of energy dissipation rate curve,of which change trend is consistent with the actual dilatancy response in marble under different stress paths.The existing empirical and theoretical dilatancy models are analyzed,which shows that the empirical dilatancy coefficient based on the energy background is more universal. 展开更多
关键词 deep marble stress paths DILATANCY energy dissipation empirical dilatancy coefficient
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Marbling计算机仿真技术综述 被引量:3
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作者 卢书芳 金小刚 《计算机辅助设计与图形学学报》 EI CSCD 北大核心 2014年第2期179-190,共12页
Marbling是一门在液体表面制作彩色流体状图案的传统手工艺术,Marbling的计算机仿真技术是现今计算机图形学领域中模拟传统绘画方法的一大组成部分.文中对现有的计算机Marbling仿真技术进行了全面的综述,并对它们在模拟方法、模拟对象... Marbling是一门在液体表面制作彩色流体状图案的传统手工艺术,Marbling的计算机仿真技术是现今计算机图形学领域中模拟传统绘画方法的一大组成部分.文中对现有的计算机Marbling仿真技术进行了全面的综述,并对它们在模拟方法、模拟对象、实现平台和输出格式等方面进行了详细介绍、分析和对比讨论;将现有仿真方法分为基于物理的模型方法和基于数学的模型方法2类,并介绍了3种不同类型的Marbling纹理图案的模拟技术.最后对全文进行总结,讨论了该领域未来的发展趋势和研究方向. 展开更多
关键词 Marbling纹理 流体模拟 数学模型 计算机艺术 水影画
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基于marble的三维可视化技术研究 被引量:1
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作者 程延锋 王俊江 +1 位作者 曹红艳 王艳侠 《微型机与应用》 2016年第9期18-19,23,共3页
随着三维可视化技术的高速发展和广泛应用,很多应用工程领域需要三维地理信息系统显示空间数据。据此介绍了marble的特点和应用方式,详细论述使用VS2008和Qt构建marble源码的基本过程。应用实例表明,基于marble的空间数据三维图形显示... 随着三维可视化技术的高速发展和广泛应用,很多应用工程领域需要三维地理信息系统显示空间数据。据此介绍了marble的特点和应用方式,详细论述使用VS2008和Qt构建marble源码的基本过程。应用实例表明,基于marble的空间数据三维图形显示真实、形象、直观。 展开更多
关键词 三维可视化 MARBLE QT VS2008
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Profile of candidate microsatellite markers in Sebastiscus marmoratus using 454 pyrosequencing 被引量:2
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作者 SONG Na 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2017年第1期198-202,共5页
Sebastiscus marmoratus is an important sedentary ovoviparous fish distributed in near-shore coastal waters from the coast of China to Japan. Candidate S. marmoratus microsatellite markers were developed in the present... Sebastiscus marmoratus is an important sedentary ovoviparous fish distributed in near-shore coastal waters from the coast of China to Japan. Candidate S. marmoratus microsatellite markers were developed in the present study using 454 pyrosequencing, and the marker profile was analyzed. A total of 2 000 000 raw sequence reads were assembled to reduce redundancy. Among them, 1 043 dinucleotide, 925 trinucleotide, 692 tetranucleotide, and 315 pentanucleotide repeats were detected. AC repeats were the most frequent motifs among the dinucleotide repeats, and AAT was the most abundant among the trinucleotide repeats. AAAT, ATAG, and ATCC were the three most common tetranucleotide motifs, and AAGAT and AATAT were the most dominant pentanucleotide motifs. The greatest numbers of loci and potentially amplifiable loci were found in dinucleotide repeats, whereas trinucleotide repeats had the fewest. In summary, a wide range of candidate microsatellite markers were identified in the present study using a rapid and efficient 454 pyrosequencing approach. 展开更多
关键词 marbled rockfish microsatellite 454 FLX pyrosequencing genomic DNA
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气-固两相旋转射流场稳定性研究
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作者 周泽宣 林建忠 《杭州应用工程技术学院学报》 1999年第4期1-7,共7页
采用考虑悬浮固粒与气流相互作用的Marble压力耦合模型和涉及悬浮固粒容积系数与平均固粒雷诺数的修正斯托克斯阻力公式,得到了含悬浮固粒的旋转射流稳定性控制方程及相应的修正瑞利稳定性准则.通过计算,给出了不同团粒属性及气相跳... 采用考虑悬浮固粒与气流相互作用的Marble压力耦合模型和涉及悬浮固粒容积系数与平均固粒雷诺数的修正斯托克斯阻力公式,得到了含悬浮固粒的旋转射流稳定性控制方程及相应的修正瑞利稳定性准则.通过计算,给出了不同团粒属性及气相跳跃速度下旋转射流的增长率和发展系数曲线,根据所得稳定性准则,得到了固粒属性对旋转射流稳定性影响的重要结论,文中结论为工程控制旋转射流场及后续发展提供了理论依据. 展开更多
关键词 气-固两相旋转射流场 稳定性 Marble压力耦合模型 修正斯托克斯阻力公式 固粒属性
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Vitamin A administration at birth promotes calf growth and intramuscular fat development in Angus beef cattle 被引量:13
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作者 Corrine L.Harris Bo Wang +6 位作者 Jeneane M.Deavila Jan R.Busboom Martin Maquivar Steven M.Parish Brent McCann Mark L.Nelson Min Du 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2018年第4期991-999,共9页
Background: Marbling, or intramuscular fat, is an important factor contributing to the palatability of beef. Vitamin A, through its active metabolite, retinoic acid, promotes the formation of new fat cells(adipogenesi... Background: Marbling, or intramuscular fat, is an important factor contributing to the palatability of beef. Vitamin A, through its active metabolite, retinoic acid, promotes the formation of new fat cells(adipogenesis). As intramuscular adipogenesis is active during the neonatal stage, we hypothesized that vitamin A administration during the neonatal stage would enhance intramuscular adipogenesis and marbling.Methods: Angus steer calves(n = 30), in a completely randomized design, were randomly allotted to three treatment groups at birth, receiving 0, 150,000, or 300,000 IU of vitamin A at both birth and one month of age.A biopsy of the biceps femoris muscle was collected at two months of age. After weaning at 210 d of age, steers were fed a backgrounding diet in a feedlot until 308 d of age, when they were transitioned to a high concentrate finishing diet and implanted with trenbolone/estradiol/tylosin mixture. Steers were harvested at an average of 438 d of age. All diets were formulated to meet nutrient requirements.Results: Weaning weight and weight during the backgrounding phase were linearly increased(P < 0.05) by vitamin A level, though no difference in body weight was observed at harvest. Intramuscular fat of steers at 308 d of age, measured by ultrasound, quadratically increased(P < 0.05) with vitamin A level from 4.0±0.26 % to 4.9±0.26 %.Similarly, carcass marbling score in the ribeye quadratically increased(P < 0.05).Conclusion: Administration of vitamin A at birth increased weaning weight and enhanced marbling fat development.Thus, vitamin A administration provides a practical method for increasing marbling and early growth of beef cattle. 展开更多
关键词 BEEF CALF CATTLE Marbling fat Quality Vitamin A
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Strainburst process of marble in tunnel-excavation-induced stress path considering intermediate principal stress 被引量:25
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作者 JIANG Bang-you GU Shi-tan +2 位作者 WANG Lian-guo ZHANG Guang-chao LI Wen-shuai 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第4期984-999,共16页
Strainburst is one type of rockburst that generally occurs in deep tunnel.In this study,the strainburst behaviors of marble specimens were investigated under tunnel-excavation-induced stress condition,and two stress p... Strainburst is one type of rockburst that generally occurs in deep tunnel.In this study,the strainburst behaviors of marble specimens were investigated under tunnel-excavation-induced stress condition,and two stress paths were designed,a commonly used stress path in true triaxial unloading rockburst tests and a new test path in which the intermediate principal stress was varied.During the tests,a high-speed camera was used to record the strainburst process,and an acoustic emission(AE)monitoring system was used to monitor the AE characteristics of failure.In these two stress paths,all the marble specimens exhibited strainbursts;however,when the intermediate principal stress was varied,the rockburst became more violent.The obtained results indicate that the intermediate principal stress has a significant effect on rockburst behavior of marble.Under a higher intermediate principal stress before the unloading,more elastic strain energy was accumulated in the specimen,and the cumulative AE energy was higher in the rockburst-induced failure,i.e.,more elastic strain energy was released during the failure.Therefore,more violent failure was observed:more rock fragments with a higher mass and larger size were ejected outward. 展开更多
关键词 strainburst true triaxial test intermediate principal stress acoustic emission MARBLE
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Zoned Zircon from Eclogite Lenses in Marbles from the Dabie-Sulu UHP Terrane,China: A Clear Record of Ultra-deep Subduction and Fast Exhumation 被引量:19
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作者 LIU Fulai A. GERDES +2 位作者 P. T. ROBINSON XUE Huaimin YE Jianguo 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2007年第2期204-225,共22页
Eclogite lenses in marbles from the Dabie-Sulu ultrahigh-pressure (UHP) terrane are deeply subducted meta-sedimentary rocks. Zircons in these rocks have been used to constrain the ages of prograde and UHP metamorphi... Eclogite lenses in marbles from the Dabie-Sulu ultrahigh-pressure (UHP) terrane are deeply subducted meta-sedimentary rocks. Zircons in these rocks have been used to constrain the ages of prograde and UHP metamorphism during subduction, and later retrograde metamorphism during exhumation. Inherited (detrital) and metamorphic zircons were distinguished on the basis of transmitted light microscopy, cathodoluminescence (CL) imaging, trace element contents and mineral inclusions. The distribution of mineral inclusions combined with CL imaging of the metamorphic zircon make it possible to relate zircon zones (domains) to different metamorphic stages. Domain 1 consists of rounded, oblong and spindly cores with dark-luminescent images, and contains quartz eclogite facies mineral inclusion assemblages, indicating formation under high-pressure (HP) metamorphic conditions of T = 571-668℃ and P =1.7-2.02 GPa. Domain 2 always surrounds domain 1 or occurs as rounded and spindly cores with white-luminescent images. It contains coesite eclogite facies mineral inclusion assemblages, indicating formation under UHP metamorphic conditions of T = 782-849℃ and P 〉 5.5 GPa. Domain 3, with gray-luminescent images, always surrounds domain 2 and occurs as the outermost zircon rim. It is characterized by low-pressure mineral inclusion assemblages, which are related to regional amphibolite facies retrograde metamorphism of T = 600- 710℃ and P = 0.7-1.2 GPa. The three metamorphic zircon domains have distinct ages; sample H1 from the Dabie terrane yielded SHRIMP ages of 245 ± 4 Ma for domain 1, 235 ± 3 Ma for domain 2 and 215± 6 Ma for domain 3, whereas sample H2 from the Sulu terrane yielded similar ages of 244 ± 4 Ma, 233 ± 4 Ma and 214 ± 5 Ma for Domains 1, 2 and 3, respectively. The mean ages of these zones suggest that subduction to UHP depths took place over 10-11 Ma and exhumation of the rocks occurred over a period of 19-20 Ma. Thus, subduction from - 55 km to 〉 160 km deep mantle depth took place at rates of approximately 9.5-10.5 km/Ma and exhumation from depths 〉160 km to the base of the crust at -30 km occurred at approximately 6.5 km/Ma. We propose a model for these rocks involving deep subduction of continental margin lithosphere followed by ultrafast exhumation driven by buoyancy forces after break-off of the UHP slab deep within the mantle. 展开更多
关键词 zoned zircon SHRIMP U-Pb dating ultra-deep subduction fast exhumation eclogite lenses in marble Dabie-Sulu UHP belt
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The Tashisayi nephrite deposit from South Altyn Tagh, Xinjiang,northwest China 被引量:8
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作者 Kong Gao Guanghai Shi +6 位作者 Meili Wang Gen Xie Jian Wang Xiaochong Zhang Ting Fang Weiyan Lei Yan Liu 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第4期1597-1612,共16页
The Tashisayi nephrite deposit is located in South Altyn Tagh.in Qiemo County,Xinjiang Province,northwest China.It is a recent discovery in the vast,well-known Kunlun-Altyn nephrite belt distributed along the south of... The Tashisayi nephrite deposit is located in South Altyn Tagh.in Qiemo County,Xinjiang Province,northwest China.It is a recent discovery in the vast,well-known Kunlun-Altyn nephrite belt distributed along the south of the Tarim Basin,producing more than half of the nephrite from the whole belt in 2017.Field investigations revealed that it is a dolomitic marble-related(D-type)nephrite deposit,but little is known about its age of formation and relationships between the granites and marble.Here we report field investigations,petrography of the neph rite,as well as petrography,geochemistry,geochronology of the zoisite-quartz altered intrusive rock and adjacent granites.An A-type granite is identified with a SHRIMP U-Pb zircon age of 926±7 Ma,suggesting it was emplaced in an extensional tectonic environment at that time.The altered intrusive rock has a cluster of U-Pb zircon age of 433±10 Ma.with similar trace element features to the A-type granite,suggesting it was formed in an extensional regime at this later time.Nephrite formed because of the metasomatism of dolomite marble by hydrothermal fluids.It is inferred that Ca^2+was released from the dolomitic marble by metasomatism forming Ca-rich fluids,which caused alteration of both the intrusive rocks(6.00-8.22 wt.%CaO)and granite(1.76-3.68 wt.%CaO)near the nephrite ore bodies.It is also inferred that Fe^2+from the granite migrated towards the dolomite marble.The fluids gave rise to the formation of Ca-minerals.such as zoisite,in the nephrite and altered intrusive rock,and epidote in the granite.Based on the contact relationships.similarity in hydrothermal processes,and consumption of Ca^2+,the Tashisayi nephrite is considered to have formed at the same time as the alteration of the intrusive rocks,i.e.~433 Ma.The geochronological similarity(~926 Ma.433 Ma)of South Altyn and North Qaidam may suggest that tectonically they belong to one single complex in the past,which was offset by the Altyn Tagh fault(ATF).The similar formation ages of the nephrites from Altyn Tagh(433 Ma)and the previously studied areas of West Kunlun(378-441 Ma)and East Kunlun(416 Ma)indicate that these nephrites formed during the closure of Proto-Tethys and in the accompanving post-collisional.extensional environment. 展开更多
关键词 NEPHRITE DOLOMITE MARBLE A-TYPE granite Altyn Tagh fault Zircon U-PB dating
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Acoustic emission activity in directly tensile test on marble specimens and its tensile damage constitutive model 被引量:13
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作者 Ruifu Yuan Bowen Shi 《International Journal of Coal Science & Technology》 EI 2018年第3期295-304,共10页
For understanding acoustic emission (AE) activity and accumulation of micro-damage inside rock under pure tensile state, the AE signals has been monitored on the test of directly tension on two kinds of marble speci... For understanding acoustic emission (AE) activity and accumulation of micro-damage inside rock under pure tensile state, the AE signals has been monitored on the test of directly tension on two kinds of marble specimens. A tensile constitutive model was proposed with the damage factor calculated by AE energy rate. The tensile strength of marble was discrete obviously and was sensitive to the inside microdefects and grain composition. With increasing of loading, the tensile stress-strain curve obviously showed nonlinear with the tensile tangent modulus decreasing. In repeated loading cycle, the tensile elastic modulus was less than that in the previous loading cycle because of the generation of micro damage during the prior loading. It means the linear weakening occurring in the specimens. The AE activity was corresponding with occurrence of nonlinear deformation. In the initial loading stage which only elastic deformation happened on the specimens, there were few AE events occurred; while when the nonlinear deformation happened with increasing of loading, lots of AE events were generated. The quantity and energy of AE events were proportionally related to the variation of tensile tangent modulus. The Kaiser effect of AE activity could be clearly observed in tensile cycle loading. Based on the theory of damage mechanics, the damage factor was defined by AE energy rate and the tensile damage constitutive model was proposed which only needed two property constants. The theoretical stress-strain curve was well fitted with the curve plotted with tested datum and the two property constants were easily gotten by the laboratory testing. 展开更多
关键词 Marble specimens Direct tensile test Acoustic emission Tensile tangent modulus Damage constitutive model
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Laboratory tests and numerical simulations of brittle marble and squeezing schist at Jinping II hydropower station,China 被引量:12
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作者 Chunsheng Zhang,Weijiang Chu,Ning Liu,Yongsheng Zhu,Jing Hou East China Investigation and Design Institute,China Hydropower Engineering Consulting Group Co.,Hangzhou,310014,China 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2011年第1期30-38,共9页
Four 16.7 km-long tunnels with diameters ranging from 12.4 to 14.6 m are now under construction at Jinping II hydropower station along the Yalong River.The tunnels pass through Triassic rocks below Jinping Mountain.Th... Four 16.7 km-long tunnels with diameters ranging from 12.4 to 14.6 m are now under construction at Jinping II hydropower station along the Yalong River.The tunnels pass through Triassic rocks below Jinping Mountain.The tunnels are characterized with high overburden,long alignment and complex geological conditions.Brittle failure in marble and squeezing in schist are the primary problems in tunnelling.This paper introduces the studies of laboratory tests on Jinping II marble as well as numerical prediction of excavation damaged zone (EDZ) of tunnel section in brittle marble and determination of reinforced concrete lining thickness for restraining time-dependent deformation in the schist tunnel section.Laboratory tests indicate that Jinping II marble presents a complex brittle-ductile-plastic transition behavior of post-peak response with increasing confining pressure.Such behavior can be described numerically with the Hoek-Brown model.The EDZ was calibrated and predicted using both fast Lagrangian analysis of continua (FLAC) and particle flow code (PFC).The predicted result of EDZ in sections with different qualities of rock mass under various overburden pressures is quite helpful in understanding EDZ characterization and support design.A power-law creep model was used to support the lining design,especially in determining the lining thickness.Field convergence measurement data over 19 months were used to calibrate the creep model properties,followed by a sensibility analysis of reinforced concrete lining thickness that was launched to present the maximum lining compressive stress. 展开更多
关键词 deep tunnel time-dependent behavior excavation damaged zone (EDZ) SQUEEZING MARBLE
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