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Study on Melting and Recrystallization of Poly(butylene succinate) Lamellar crystals via Step Heating Differential Scanning calorimetry

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chinese Journal of Polymer Science 2017年第12期35卷 1552-1560页

作者： Zhi-yu Lv michael c.Zhang Yang Zhang Bao-hua Guo 徐军 Key Laboratory of Advanced Materials (Ministry of Education) Department of Chemical Engineering Tsinghua University

Differential scanning calorimetry（DSc） has been widely applied to study crystallization and melting of materials. However, for polymeric lamellar crystals, the melting thermogram during heating process usually exhibits a broad endothermic peak or even multiple endotherms, which may result from changes of metastability via recrystallization process. Sometimes, the recrystallization exotherm cannot be observed due to its overlapping with the melting endotherm. In this work, we employed a step heating procedure consisting of successive heating and temperature holding stages to measure the metastability of isothermally crystallized poly（butylene succinate）（PBS） crystals. With this approach we could gain the fraction of crystals melted at different temperature ranges and quantitatively detect the melting-recrystallization behavior. The melting-recrystallization behavior depends on the polymer chain structure and the crystallization temperature. For instance, PBS block copolymer hardly shows recrystallization behavior while PBS oligomer and high molecular weight PBS homopolymer demonstrate remarkable melting-recrystallization phenomenon. High molecular weight PBS isothermally crystallized in the low temperature range shows multiple melting-recrystallization while those isothermally crystallized at elevated temperatures do not exhibit observable recrystallization behavior. Furthermore, the melting endotherms were fitted via the melting kinetics equations. The original isothermally crystallized lamellae demonstrate quite different melting kinetics from the recrystallized lamellar crystals that melt at the highest temperature range, which is attributed to the different degrees of stabilization. Finally, the mechanism of melting-recrystallization is briefly discussed. We propose that apparent meltrecrystallization phenomenon be observed when melting of preformed lamellar crystals and recrystallization of thicker lamellae have similar free energy barrier.

关键词： DSc Step heating Poly(butylene succinate) Metastability Melting-recrystallization Melting kinetics

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Assessment of internal defects of hardfacing coatings in regeneration of machine parts

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Journal of central South University 2018年第5期25卷 1144-1153页

作者： Jerzy JOZWIK Krzysztof DZIEDZIc Ireneusz USYDUS Dawid ostrowski Grzegorz M KROLcZYK Faculty of Mechanical Engineering Lublin University of Technology Electrical Engineering and computer Science Faculty Lublin University of Technology Institute of Technical Sciences and Aviation State School of Higher Education Faculty of Mechanical Engineering Opole University of Technology

This paper presents the use of computed tomography for the evaluation of hardfacing. The method used in this research is hardfacing by tungsten inert gas using alloy wires of wear resistant layers. This paper discusses the latest materials used for hardfacing and their application. It characterizes the defects of obtained hardfacing and impact of the type of wire on the concentration of defects. It further, the basic mechanical properties of coatings were determined. The results are subjected to qualitative and quantitative analysis. The smallest average percentage of defects in relation to the overall surface is observed for the hardfacing EL-600 HB, which amounts to 1.5%. The highest average percentage of defects in relation to the overall surface is observed for the hardfacing EL-500 HB, which amounts to 7.2%. The chemical composition of hardfacing has been presented.

关键词： hardfacing coating tomography welding defects

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Endocrine stress response of Eastern Fence Lizards in fire-disturbed landscapes

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current Zoology 2019年第6期65卷 643-650页

作者： michael G.IAccHETTA K.Nichole MALONER c.M.GIENGER Department of Biology and center of Excellence for Field Biology Austin Peay State University ClarksvilleTNUSA Department of Forestry and Natural Resources Purdue UniversityWest LafayetteINUSA Department of Pathology Microbiologyand ImmunologyVanderbilt University Medical Center NashvilleTNUSA

Landscape disturbances can alter habitat structure and resource availability,often inducing physiological responses by organisms to cope with the changing *** the endocrine stress response through measurement of glucocorticoids has become an increasingly common method for determining how organisms physiologically respond to challenges imposed by their *** tested the hypothesis that Eastern Fence Lizards cope with fire disturbance effects by modulating their secretion of corticosterone(cORT).We measured the baseline and stress-induced plasma cORT of male Eastern Fence Lizards in a chronosequence of fire-altered habitats(recently burned,recovering from burn,and unburned).Although habitat use by lizards differed among burn treatments,including differences in use of canopy cover,leaf litter,and vegetation composition,we did not detect a significant effect of fire-induced habitat alteration on plasma cORT concentration or on body *** addition,we found no effect of blood draw treatment(baseline or stress-induced),body temperature,body condition,or time taken to collect blood samples on concentration of plasma *** intensity burns,which are typical of prescribed fire,may not be a sufficient stressor to alter cORT secretion in Eastern Fence Lizards(at least during the breeding season).Instead,lizards may avoid allostatic overload using behavioral responses and by selecting microsites within their environment that permit thermoregulatory opportunities necessary for optimal performance and energy assimilation.

关键词： endocrine response fire ecology habitat alteration prescribed fire reptile Sceloporus undulatus

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Optimization and kinetics of glucose production via enzymatic hydrolysis of mixed peels

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Journal of Bioresources and Bioproducts 2020年第4期5卷 283-290页

作者： michael U.Ude Ike Oluka Paul c.Eze Engineering Research Development and Production Projects Development Institute(PRODA)EmeneEnugu StateNigeria Department of Agricultural and Bioresource Engineering Enugu State University of Science and Technology(ESUT)Enugu StateNigeria

The optimization and kinetics of glucose production via enzymatic hydrolysis of mixed peels were carried *** substrate was characterized using proximate analysis and *** process was optimized using response surface methodology while the kinetics of the hydrolysis was studied using Michealis-menten *** results obtained showed that the mixed peels have high hemicellulose content,hydrolysable carbohydrate and *** optimum conditions for glucose yield of 79%by enzymatic hydrolysis are temperature of 36℃,time of five days,pH of 4.55 and enzyme dosage of 0.428 g/50 *** hydrolysis obeyed Michealis-Menten kinetic model with spontaneous and feasible ***,the results have proved that mixed peels(cassava and potato peels)is a good substrate for glucose production and study of other waste peels as feed-stock is recommended.

关键词： Enzymatic hydrolysis Optimization Glucose cassava and potato peels

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Integrating flood depth and plant resistance with chlorantraniliprole seed treatments for management of rice water weevil, Lissorhoptrus oryzophilus （coleoptera： curculionidae）

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Insect Science 2015年第5期22卷 679-687页

作者： Srinivas K. Lanka David c. Blouin michael J. Stout Department of Entomology Louisiana State University Agricultural Center Baton Rouge LA 70803 USA

chlorantraniliprole seed treatments in rice provide effective suppression of rice water weevil populations in the United States; however, heavy reliance on prophylac- tic insecticide treatments as a sole strategy could destabilize management programs for this insect. The present research evaluated the compatibility of seed treatments with two other potential management tactics--plant resistance and shallow flooding-by conducting two split-plot experiments in 2009 and 2011. In both experiments, no substantial antago- nism was found among the 3 different tactics. Statistical interactions in these experiments arose from the strong and persistent effects of chlorantraniliprole on larval densities rather than incompatibility of tactics. In 2009, weevil densities differed among varieties and were significantly lower on the cultivar ＂Jefferson.＂ In 2011, weevil densities were reduced sig- nificantly in shallow-flooded plots compared to deep-flooded plots. Significant reductions in weevil numbers by chlorantraniliprole seed treatments, even at application rates 5 fold lower than commercially recommended rates, demonstrated the potential to reduce appli- cation rates of this highly potent larvicide. These latter results suggest that future studies on the relationship between chlorantraniliprole seed treatment rate and weevil fitness are warranted.

关键词： chlorantraniliprole compatibility integrated management plant resistance rice water weevil seed treatments

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Molecular genetics of ependymoma

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chinese Journal of cancer 2011年第10期30卷 669-681页

作者： Yuan Yao Stephen c. Mack michael D. Taylor Division of Neurosurgery Arthur and Sonia LabattBrain Tumour Research Centre Hospital for Sick Children TorontoOntario Canada Department of Laboratory Medicine and Pathobiology University of Toronto Toronto Ontario Canada.

Brain tumors are the leading cause of cancer death in children,with ependymoma being the third most common and posing a significant clinical *** mechanism of pathogenesis,reliable prognostic indicators,and effective treatments other than surgical resection have all remained *** recently,ependymoma research was hindered by the small number of tumors available for study,low resolution of cytogenetic techniques,and lack of cell lines and animal *** heterogeneity,which manifests as variations in tumor location,patient age,histological grade,and clinical behavior,together with the observation of a balanced genomic profile in up to 50% of cases,presents additional challenges in understanding the development and progression of this *** these difficulties,we have made significant headway in the past decade in identifying the genetic alterations and pathways involved in ependymoma tumorigenesis through collaborative efforts and the application of microarray-based genetic(copy number) and transcriptome profiling *** characterization of ependymoma unraveled distinct mRNA-defined subclasses and led to the identification of radial glial cells as its cell type of *** review summarizes our current knowledge in the molecular genetics of ependymoma and proposes future research directions necessary to further advance this field.

关键词：分子遗传学室管膜肿瘤发生发病机制手术切除动物模型遗传变异遗传特性

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Statistics of the Nicocr medium-entropy alloy:Novel aspects of an old puzzle

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npj computational Materials 2020年第1期6卷 610-615页

作者： Zongrui Pei Rui Li michael c.Gao G.Malcolm Stocks Oak Ridge National Laboratory Oak RidgeTN 37831USA University of Tennessee KnoxvilleTN 37996USA National Energy Technology Laboratory AlbanyOR 97321USA Leidos Research Support Team 626 Cochrans Mill RoadP.O.Box 10940PittsburghPA 15236USA

We study the K-state phenomenon in the Nicocr medium-entropy alloy using first-principles techniques jointly with the efficient Wang–Landau Monte carlo and simulated annealing *** theoretical results successfully explain the existence of the peak around 940 K in the experimental specific heat curve that characterizes the K-state phenomenon and give a fine picture of its atomic *** peak is caused by the maximum change of the local configurations characterized by the short-range-order(SRO)parameters at that temperature.

关键词： alloy temperature entropy

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Allometric models for estimating aboveground biomass in the tropical woodlands of Ghana, West Africa

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Forest Ecosystems 2020年第3期7卷 539-561页

作者： Raymond Aabeyir Stephen Adu-Bredu Wilson Agyei Agyare michael J.c.Weir Department of Environment and Resource Studies UDS-Wa CampusWaGhana WAScAL Graduate Research Programme on climate change and Land Use KNUSTKumasiGhana Biodiversity conservation and Ecosystem Division CSIR-Forestry Research Institute of GhanaKumasiGhana Department of Agricultural and Biosystems Engineering KNUSTKumasiGhana Department of Natural Resources Faculty of Geoinformation Science and Earth Observation(ITC)University of TwenteEnschedethe Netherlands

Background: Modelling aboveground biomass(AGB) in forest and woodland ecosystems is critical for accurate estimation of carbon stocks. However, scarcity of allometric models for predicting AGB remains an issue that has not been adequately addressed in Africa. In particular, locally developed models for estimating AGB in the tropical woodlands of Ghana have received little attention. In the absence of locally developed allometric models, Ghana will continue to use Tier 1 biomass data through the application of pantropic models. Without local allometric models it is not certain how Ghana would achieve Tier 2 and 3 levels under the United Nations programme for reducing emissions from deforestation and forest degradation. The objective of this study is to develop a mixedspecies allometric model for use in estimating AGB for the tropical woodlands in Ghana. Destructive sampling was carried out on 745 trees(as part of charcoal production) for the development of allometric equations. Diameter at breast height(dbh, i.e. 1.3 m above ground level), total tree height(H) and wood density(ρ) were used as predictors for the models. Seven models were compared and the best model selected based on model efficiency,bias(%) and corrected Akaike Information criterion. The best model was validated by comparing its results with those of the pantropic model developed by chave et al.(Glob chang Biol 20:3177–3190, 2014) using equivalence test and conventional paired ***: The results revealed that the best model for estimating AGB in the tropical woodlands is AGB =0.0580ρ((dbh)2 H)0.999. The equivalence test showed that this model and the pantropic model developed by chave et al.(Glob chang Biol 20:3177–3190, 2014) were equivalent within ±10% of their mean predictions(p-values cant level), while the paired t-test revealed that the mean(181.44 ± 18.25 kg) of the model predictions of the best model of this s

关键词： charcoal Diameter at breast height Tree height Wood density Savannah woodland

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The brazing of diamond

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金刚石与磨料磨具工程 2008年第S1期28卷 134-142页

作者： Sung michael Sung James c. Advanced Diamond Solutions Inc.351 King Street Suite 813San FranciscoCA 94158U.S.A. KINIK company 64Chung-San Rd.Kuo-Ying National Taiwan UniversityTaipei 106 Taiwan National Taipei University of Technology

Diamond grits held in metal matrix(sintered or electroplated) are retained primary by mechanical *** of this weak attachment,the pullouts of diamond from matrix are inevitable during the cutting ***,the working grits have low protrusion heights,so the cutting speed of the tool is limited. Furthermore,the rubbing of metal matrix and the work object can cause thermal damages of diamond and other materials,and power increase for the operation. Diamond can be firmly held in a metal matrix by *** of the presence of strong chemical bonding,diamond grits can protrude twice as high without being knocked off from the *** a result,the cutting speed of the tool may be doubled. When the braze melts,the carbide formers will migrate toward diamond to form carbide at the interface. This reaction may be excessive as to degrade diamond *** this case,a coating on diamond may be needed to moderate the reaction. When diamond is brazed on the surface of a substrate,the melt tends to pull the grits closer together that may thicken the braze layer *** clustering of grits can reduce the cutting effectiveness of the diamond tool.A diamond grid design is necessary to maintain the uniform thickness of the braze ***,the controlled melting of braze alloy can form a gentle slope around each diamond *** a massive support can allow aggressive cutting of the diamond tool with a low power consumption.

关键词： diamond brazing diamond dresser pad conditioner diamond adherence diamond distribution chemical mechanical planarization

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A cOMPUTER MODEL OF DERIVATIVE METHOD FOR POINT SOURcE GRAVITY WAVES IN ATMOSPHERE

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Science china Mathematics 1992年第11期35卷 1374-1387页

作者：庄洪春 cHAO H.LIU michael c.KELLEY Research center of Space Science and Applications Academia Sinica Beljing 100080 PRC Department of Electrical and computer Engineering University of Illinois at Urbana-Champaign USA School of Electrical Engineering Cornell University Ithaca NY USA

Analytical Solutions of point source gravity wave s in an isothermal atmosphere are given.A computer model based on the analytical solutions is developed for point source gravity waves in a horizontally and isothermally stratified *** numerical calculation of the propagation of point source gravity waves in a tealistic atmosphere then becomes feasible. The propagation of point source acoustic waves in the atmosphere can also be numerically calculated using the same model.

关键词： atmospheric gravity waves atmospheric waves acoustic-gravity waves.

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