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Pore characterization of PM Mg–0.6Ca alloy and its degradation behavior under physiological conditions

Journal of Magnesium and Alloys 2021年第2期9卷 686-703页

作者： Eshwara Phani Shubhakar Nidadavolu Diana.krüger Berit Zeller-Plumhoff Domonkos Tolnai Björn Wiese Frank Feyerabend Thomas Ebel Regine Willumeit-Römer Division Metallic Biomaterials Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany Magnesium Innovation Center(MagIC) Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany

Several material parameters affect degradation characteristics of Mg and its alloys under physiological *** Mg materials are interesting for their simultaneous degradation and drug delivery ***,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical *** present work aims at determining the threshold porosity value in Mg–0.6 Ca specimens produced by powder metallurgy(PM)below which low degradation rates persist with acceptable mechanical *** different porous Mg–0.6 Ca specimens containing both closed and open pore structures were fabricated with porosities ranging from 3%to 21%.Degradation profiles were obtained via a semi static immersion test over 16 days under physiological conditions using Dulbecco’s modified Eagle’s medium with Glutamax and 10%fetal bovine serum as *** results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT *** general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the *** degradation rates(MDR<0.3 mm/year)are observed in specimens until 10%porosity,however,the upper bound for reproducible degradation is observed to be in specimens until 12%*** porosity level also marks the transition from closed to open pore nature with a simultaneous change in pore interconnectivity from less than 10%to greater than 95%,below and above this porosity level,*** tensile strength and elongation to failure recorded for specimens with 10%porosity were 70 MPa and 2%,respectively displaying positive traits of both homogenous degradation and mechanical *** results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca *** results also indicate a good sintering respons

关键词： Porous Mg-0.6Ca In vitro Degradation μCT Sintering

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Optimization of Tribological Performance of Al-6061T6-15% SiCp-15% Al2O3Hybrid Metal Matrix Composites Using Taguchi Method &Grey Relational Analysis

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Journal of Minerals and Materials Characterization and Engineering 2014年第4期2卷 351-361页

作者： Ashok kr. Mishra Vinod Kumar Rajesh kr. Srivastava BIT Sindri Dhanbad India BRCM College of Engineering & Technology Bahal India SKIET Kurukshetra India

In this investigation, optimization of tribological performance parameters of Al-6061T6 alloy reinforced with SiC (15% by weight) and Al2O3 (15% by weight) particulates having particle size of 37 μm each has been presented. The wear and frictional properties of the hybrid metal matrix composites have been studied by performing dry sliding wear test using pin-on-disc wear tester. A L27 orthogonal array is selected for the analysis of the data. From the test results it is observed that sliding distance has the significant contribution in controlling the friction and wear behaviour of hybrid composites. A confirmation test is also carried out to verify the accuracy of the results obtained through the optimization. In addition an optical micrograph test is also performed on the wear tracks to study the wear mechanism.

关键词： Metal Matrix Composites (MMCs) Friction Wear Taguchi Method Grey Relational Analysis Analysis of Variance (ANOVA)

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Multicriteria to estimate the environmental risk of sediment from the Obedska Bog(Northern Serbia),a reservation area on UNESCO's list

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International Journal of Sediment Research 2020年第5期35卷 527-539页

作者： Dejan kr?mar Nenad Grba Marijana.kragulj Isakovski Nata?a Varga Jelena Spasojevi? Jasmina Agbaba Bozo Du?an Dalmacija University of Novi Sad Faculty of Sciences Department of ChemistryBiochemistry and Environmental Protection

The objective of this current study is to compare related sediment legislation standards and norms to the diversity and influence of anthropogenic and natural(geogenic) sources of pollution in the investigated fluvial relief test site region of the Obedska *** metals(nickel(Ni).zinc(Zn),cadmium(Cd),copper(Cu) and lead(Pb) except chromium(Cr)) and arsenic(As) have higher values than the Upper Continental Crust(UCC) for loess *** sharp leaps in the enrichment factor(r) suggested "indicators of anthropogenic metal pollution" for Cd,Cu(r> 5.0) and Zn,Ni(r> 1.0) for this *** addition,the Chemical Proxy of Alteration(CPA,60-95) from the unique Jadar block terrane and neighbouring representative catchment areas,confirmed moderate to higher intensity of *** Component Analysis/Factor Analysis(PCA/FA) and cluster analysis suggest that Ni,Zn,Cu and Cd are derived from several anthropogenic sources,whereas As is convincingly of geogenic origin,and Pb and Cr exhibit dual *** sum of 16 *** Protection Agency Polycyclic Aromatic Hydrocarbons(EPA PAHs) indicated heterogenic sources,but minor effects to *** results of the current investigation indicated intensive and highly diffuse sources of pollution in this United Nations Educational,Scientific and Cultural Organization [UNESCO's] *** outcomes indicate that Cu should be added to the European Union [EU] watch list of emerging contaminants.

关键词： Priority substances in sediment Contamination criteria Multivariate statistical techniques Heterogeneous sources

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Multiple Sclerosis:A Mast Cell Mediated Psycho-Somatic Disease?

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World Journal of Neuroscience 2018年第4期8卷 444-453页

作者： Per Goran krüger University of Bergen BergenNorway

This paper reviews evidence that the presence of mast cells in specific sites of central nervous system, suggesting inflammatory processes, may explain all the symptoms observed in multiple sclerosis. This hypothesis ... 详细信息

关键词： Multiple Sclerosis Mast Cells Blood-Brain Barrier Oedemas Plaque Formation Relapsing-Remitting MS Primary and Secondary Progressive MS Nutrition Stress Enteroendocrine System

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Accordion Manoeuvre with Ilizarov Frame over Nail in Situin a Case of Infected Non-Union of Femur: Discussion on Strategies: A Case Report

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Open Journal of Orthopedics 2014年第7期4卷 183-188页

作者： Ranjit kr. Baruah Department of Orthopaedics Assam Medical College Dibrugarh India

Quiescent Type of H. Rosen & Stage 2 of C.L. Romano et al. for Infected Non Union of Femur after K-nailing (Küntscher nailing) require no debridement & removal of nail and therefore can be treated by a single stage procedure. There are a few reports of treating aseptic non-union of femur by compression alone or compression distraction over nail by Ilizarov Technique. However, no case of Infected Non-Union femur being treated by Accordion Manoeuvre with Ilizarov over nail in situ (i.e. without exchange nailing) has been reported so far. Here, we are reporting a case of Infected Non-Union following K-nailing for a fracture shaft of femur in a 15-year-old female, who was treated by this technique as a single stage procedure. An Ilizarov frame was mounted on the femur with nail in situ followed by Accordion Manoeuvre. The fracture was healed in 5.6 months with two cycles of Accordion Manoeuvre followed by rhythmic compression. There was no recurrence of infection.

关键词： Infected Non-Union Femur Accordion Manoeuvre by Ilizarov over Nail in Situ

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蒙特卡罗哈密顿新方案及其检验

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高能物理与核物理 2005年第9期29卷 928-932页

作者：黄纯青罗向前 H.krger 中山大学理工学院物理学系 Département de Physique Université LavalQuébecPQ G1K 7P4Canada

蒙特卡罗哈密顿方法(MCH)是研究量子理论的数值模拟新方法,其优点是可求出超出基态的能谱和波函数.旧MCH方案需要自由粒子的信息,较难推广应用于格点规范理论.本文提出克服这个困难的新方案.首先介绍这一方案的思想,并以1维量子力学模型... 详细信息

蒙特卡罗哈密顿方法(MCH)是研究量子理论的数值模拟新方法,其优点是可求出超出基态的能谱和波函数.旧MCH方案需要自由粒子的信息,较难推广应用于格点规范理论.本文提出克服这个困难的新方案.首先介绍这一方案的思想,并以1维量子力学模型V(x)=μ2x2+λx4(其中μ20)为例说明实现这一新方案的具体计算步骤和方法.

关键词：蒙特卡罗等效哈密顿量新方案波函数能谱哈密顿检验格点规范理论量子力学模型数值模拟

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Effect of irrigation water containing arsenic on elemental composition of bean and lettuce plants cultivated in calcareous sandy soil

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食物生产加工与营养(英文) 2019年第1期1卷 1-10页

作者： Sirat Sandil Péter Dobosy krisztina.kröpfl Anna Füzy MihályÓvári Gyula Záray MTA Centre for Ecological Research Danube Research InstituteKarolinaút 29-31Budapest H-1113Hungary Cooperative Research Centre of Environmental Sciences Eötvös Loránd UniversityPázmány Péter sétány 1/ABudapest H-1117Hungary MTA Centre for Agricultural Research Institute for Soil Sciences and Agricultural ChemistrHerman Ottóút 15Budapest H-1022Hungary

Background:The uptake of arsenic by vegetables from soil irrigated with arsenic enriched groundwater poses a major health *** edible portion of these vegetables transfer arsenic to the human *** uptake of arsenic was studied in bean(Phaseolus vulgaris L.)and lettuce(Lactuca sativa L.)in a controlled greenhouse pot culture with calcareous sandy soil as *** plants were irrigated with water containing sodium arsenate at concentrations 0.1,0.25 and 0.5 mg L^(-1).The total arsenic concentration of the different plants parts was determined by ICP-MS,following microwave-assisted acid *** change in plant biomass production and essential macroelements(Mg,P,K)and microelements concentration(Fe,Mn,Cu,Zn)was also ***:The As concentration in the bean was in the order:root>stem>leaf>bean fruit and in lettuce:root>*** the highest dose(0.5 mg L^(-1))the As concentration in the bean fruit and lettuce leaves was 22.1μg kg^(-1)and 1207.5μg kg^(-1)DW,*** As concentration in the irrigation water resulted in decreased edible biomass production in bean,while in lettuce the edible biomass production *** plant exhibited any visible toxicity *** significant change was observed in the macro and microelements *** total and the water-soluble arsenic in soil amounted to 3.5 mg kg^(−1)and 0.023 mg kg^(−1),*** transfer factor was found to increase with increase in the As treatment *** transfer factor range for bean from root to fruit was 0.003–0.005,and for lettuce from root to leaves was 0.14–***:Considering the FAO-WHO recommended maximum tolerable daily intake(MTDI)limit of 2.1μg kg^(-1)body weight,and the biomass production,both plants should not be cultivated at As treatment level higher than 0.1 mg L^(-1).

关键词： Arsenic irrigation water uptake transfer factor calcareous sandy soil vegetables

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The growth of Staphylococcus aureus and Escherichia coli in low-direct current electric fields

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International Journal of Oral Science 2014年第1期6卷 7-14页

作者： Dunya Zituni Heidi Schtt-Gerowitt Marion Kopp Martin krnke Klaus Addicks Christian Hoffmann Martin Hellmich Franz Faber Wilhelm Niedermeier Department of Prosthetic Dentistry School of Dental and Oral Medicine Cologne University Institute for Medical Microbiology Immunology and HygieneCologne University Institute for Anatomy I Cologne University Institute for Medical Statistics Informatics and Epidemiology Cologne University Department of Pre-Clinical Dentistry School of Dental and Oral Medicine Cologne University

Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths （EFS） on the growth of Staphylococcus aureus （ATCC 25923） and Escherichia coil （ATCC 25922） in vitro. Cultures of S. aureus and E. coil in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureuswere larger than those for E. coliat all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 V.m-1. Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coll.

关键词： direct current Escherichia coli electrogaNanism gold electrode Staphylococcus aureus

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计算机模拟与实验:校内校外教学比较研究

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中国校外教育 2024年第2期 104-128页

作者：约翰娜·克鲁格蒂姆·霍夫勒马丁·沃尔凯特琳·尼克梅耶伊尔卡·帕奇曼华静(译) 朱子健(译) 陈香(译) 房传修(译) Leibniz Institute for Science and Mathematics Education GEOMAR Helmholtz Centre for Ocean Research Kiel 华东理工大学外语学院上海理工大学外语学院

在现代科学教育中,交互式计算机模拟与实操性实验是两种重要的教学方法。已有研究未能充分阐释这两种方法的优劣,也未能对二者进行充分的比较。本文将二者作为科学教育的学习工具,在不同的学习地点(研究Ⅰ:学校;研究Ⅱ:科学中心的学生... 详细信息

在现代科学教育中,交互式计算机模拟与实操性实验是两种重要的教学方法。已有研究未能充分阐释这两种方法的优劣,也未能对二者进行充分的比较。本文将二者作为科学教育的学习工具,在不同的学习地点(研究Ⅰ:学校;研究Ⅱ:科学中心的学生实验室)的学生间,从学科知识成绩、情境兴趣发展和认知负荷方面进行了比较研究。研究结果显示,无论学习地点在哪,使用计算机模拟的学生比进行实操性实验的学生认知负荷更高,但学习成功率也要高。与计算机模拟(特别是当认知和价值相关时)相比,实操性实验更能促进情境兴趣。研究认为讲授复杂的话题运用计算机模拟可能更为适合。但其他相关研究发现表明,使用一种教学方法可以弥补另一种教学方法的缺陷。综合以上研究得出,最有效的方式是将这两种方法结合起来,这有助于在校内外学习环境中成功地进行现代科学教育。

关键词：科学教育实操性实验计算机模拟学习兴趣

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Assessing the microstructure and in vitro degradation behavior of Mg-xGd screw implants using μCT

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Journal of Magnesium and Alloys 2021年第6期9卷 2208-2223页

作者： Diana.krüger Berit Zeller-Plumhoff Björn Wiese Sangbong Yi Marcus Zuber D.C.Florian Wieland Julian Moosmann Regine Willumeit-Römer Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Institute of Material and Process Design Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Institute for Photon Science and Synchrotron Radiation Karlsruhe Institute of TechnologyHerrmann-von-Helmholtz-Platz 1Eggenstein-Leopoldshafen 76344Germany Laboratory for Applications of Synchrotron Radiation Karlsruhe Institute of TechnologyKaiserstr.12KarlsruheGermany Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany

Biodegradable implants are taking an increasingly important role in the area of orthopedic implants with the aim to replace permanent implants for temporary bone healing *** the implant preparation process,the material’s surface and microstructure are being changed by stresses induced by *** degradable metal implants need to be fully characterized in terms of the influence of machining on the resulting microstructure and corrosion *** this study,micro-computed tomography(μCT)is used for the quantification of the degradation rate of biodegradable *** our best knowledge,for the first time quantitative measures are introduced to describe the degradation homogeneity in *** information enables a prediction in terms of implant stability during the degradation in the *** magnesium gadolinium alloys,Mg-5Gd and Mg-10 Gd(all alloy compositions are given in weight%unless otherwise stated),in the shape of M2 headless screws have been investigated for their microstructure and their degradation performance up to 56 *** the microstructure investigations particular attention was paid to the localized deformation of the alloys,due to the machining *** vitro immersion testing was performed to assess the degradation performance quantified by subsequent weight loss and volume loss(usingμCT)*** differences were observed in the degree of screw’s near surface microstructure being influenced from machining,the degradation rates of both materials appeared to be suitable for application in orthopedic *** the degradation homogeneity point of view no obvious contrast was detected between both ***,the higher degradation depth ratios between the crests and roots of Mg-5Gd ratios may indicated a less homogeneous degradation of the screws of these alloys on contract to the ones made of Mg-10Gd *** to its lower degradation rates,its more homogeneous microstructure,its weaker texture

关键词： Magnesium alloys Biodegradable implant Degradation rate Degradation homogeneity Micro-comptued tomography

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