检索结果-南通市图书馆

Ground vegetation,forest floor and mineral topsoil in a clear-cutting and reforested Scots pine stands of different ages:a case study

引用

Journal of Forestry Research 2022年第4期33卷 1247-1257页

作者： DovilėGustienė Iveta Varnagirytė-Kabašinskienė Vidas Stakėnas Lithuanian Research Centre for Agriculture and Forestry Liepųstr.1Girionys53101 Kaunas DistrictLithuania Kaunas Forestry and Environmental Engineering University of Applied Sciences Liepųstr.1Girionys53101 Kaunas DistrictLithuania

Scots pine(Pinus sylvestris L.)is a dominant tree species on nutrient-poor sandy soils in the Baltic region’s hemiboreal forests.A final clear-cut in commercial stands is a common ***,the maintenance of relatively stable vegetation indices and ecological processes throughout the rotation promote new scientific and social ***,clear-cuttings disturb forest functions for a certain period,i.e.,phytocenoses with forest-based species composition,biodiversity,and vegetation *** organic carbon(SOC)and nutrients can also be *** key indices,ground vegetation,SOC and main nutrients in the forest floor and in 40-cm topsoil layer were analysed in the clear-cuttings(not reforested)and in reforested 10-,30-,and 101-year-old Scots pine stands in *** results show an increase in species richness at the beginning of stand formation up to 30 years after clear-cutting;species typical of a mature forest occurred relatively quickly *** mean mass of forest floor vegetation was negatively related to the richness of ground vegetation *** floor p H consequently decreased with stand *** SOC levels were in the mature *** the mineral topsoil layers,total SOC and total nitrogen were in the upper 10-cm layer in the 30-year-old stand.A post-harvest peak in mineral N concentration was observed and other nutrients,especially mobile PO,KO,Caand Mg,increased the clear-cuttings and in the 10-year-old stand compared to the mature stand.

关键词： Pinus sylvestris Species cover Richness Soil organic carbon Soil nutrients Mature stand

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

In silico studies of magnesium-based implants: A review of the current stage and challenges

引用

Journal of Magnesium and Alloys 2022年第11期10卷 2968-2996页

作者： Tamadur Albaraghtheh Regine Willumeit-Römer Berit Zeller-Plumhoff Helmholtz-Zentrum hereon GmbH Institute of Metallic BiomaterialsMax-Planck-Str.1Geesthacht 21502Germany

In silico methods to study biodegradable implants have recently received increasing attention due to their potential in reducing experimental time and cost. An important application case for in silico methods are magnesium(Mg)-based biodegradable implants, as they represent a powerful alternative to traditional materials used for temporary orthopaedic applications. Controlling Mg alloy degradation is critical to designing an implant that supports the bone healing process. To simulate different aspects of this biodegradation process, several mathematical models have been proposed with the ultimate aim of replacing laboratory experiments with computational modeling. In this review, we provide a comprehensive and critical discussion of the published models and their performance with respect to capturing the complexity of the biodegradation process. This complexity is presented initially. Additionally, the present review discusses the different approaches of optimizing and quantifying the different sources of errors and uncertainties within the proposed models.

关键词： Biodegradable implants Degradation In silico Phenomenological approach Physical approach Validation Verification Uncertainty quantification Mg

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Peri-implant gas accumulation in response to magnesium-based musculoskeletal biomaterials:Reframing current evidence for preclinical research and clinical evaluation

引用

Journal of Magnesium and Alloys 2024年第1期12卷 59-71页

作者： Yu Sun Heike Helmholz Regine Willumeit-Römer Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany

Historically,the rapid degradation and massive gas release from magnesium(Mg)implants resulted in severe emphysema and mechanical *** the advent of new alloys and surface treatment methods,optimized Mg implants have re-entered clinics since last decade with reliable ***,the optimization aims at slowing down the degradation process,rather than exemption of the gas *** study involved a systematic evaluation of current preclinical and clinical evidence,regarding the physical signs,symptoms,radiological features,pathological findings and complications potentially associated with peri±implant gas accumulation(PIGA)after musculoskeletal Mg *** literature search identified 196 potentially relevant publications,and 51 papers were enrolled for further analysis,including 22 preclinical tests and 29 clinical studies published from 2005 to *** Mg-based materials have been evaluated in animal research,and the application of pure Mg and Mg alloys have been reported in clinical follow-ups involving multiple anatomical sites and musculoskeletal *** tissue and intraosseous PIGA are common in both animal tests and clinical follow-ups,and potentially associated with certain adverse *** examinations especially micro-CT and clinical CT scans provide valuable information for quantitative and longitudinal *** according to simulation tests involving Mg implantation and chemical processing,tissue fixation could lead to an increase in the volume of gas cavity,thus the results obtained from ex vivo imaging or histopathological evaluations should be interpreted with *** still lacks standardized procedures or consensus for both preclinical and clinical evaluation of ***,by providing focused insights into the topic,this evidence-based study will facilitate future animal tests and clinical evaluations,and support developing biocompatible Mg implants for the treatment of musculoskeletal

关键词： Magnesium implant Degradation Hydrogen Gas release Postoperative follow-up

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Comparison between compression tested and simulated Mg-6.3Gd bone scaffolds produced by binder based additive manufacturing technique

引用

Journal of Magnesium and Alloys 2023年第8期11卷 2750-2762页

作者： Martin Wolff Mohammad Marvi-Mashhadi Eshwara Nidadavolu Henrik Lüneburg Thomas Ebel Regine Willumeit-Römer Institute of Metallic Biomaterials at Helmholtz-Zentrum Hereon Max-Planck Str.1D-21502 GeesthachtGermany Institute of Material Systems Modeling Helmholtz-Zentrum HereonMax–Planck-Str.121502 GeesthachtGermany

In this study,a binder based 3D-printing technology *** Granular Fabrication(FGF)technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test *** consolidation of the green parts(as printed scaffolds)was performed using solvent debinding in cyclohexane and subsequent conventional sintering in argon *** tests were performed on as sintered ***,a simulation strategy was developed for modeling the compression behavior of the sintered parts,utilizing the data from the experimental *** experimental compression test results and the simulation strategy for the compression behavior of the 3D-printed scaffolds demonstrated good agreement.

关键词： Magnesium Mg-6.3Gd Additive manufacturing Simulation FGF Biodegradable

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

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

引用

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(MDR10%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

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Alloying effect of silver in magnesium on the development of microstructure and mechanical properties by indirect extrusion

引用

Journal of Magnesium and Alloys 2021年第1期9卷 112-122页

作者： Bjorn Wiese Regine Willumeit-Römer Dietmar Letzig Jan Bohlen 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

The effect of Ag in solid solution on the microstructure,texture and the deformation behaviour of indirectly extruded Mg was *** as a solid solution strengthener affects the behaviour during extrusion,resulting in enhanced deformation related heating and corresponding coarser grained *** substantial effect on the texture development is *** mechanical properties simultaneously increase in stress and strain levels with increasing Ag content,especially in tension as a result of the changing impact of the slip modes which can be associated with a decrease of the lattice parameters as well as the c/a ratio of the hcp lattice *** compression tests with twin dominated flow,the impact is much smaller on the compressive yield stress but higher with respect to the twinning related strain hardening *** solution strength functions for Fleischer and Labusch were determined,also confirming the anisotropic behaviour of the extruded Mg alloys.

关键词： Mg-Ag-alloys Lattice parameters Indirect extrusion Microstructure Mechanical properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Heterotopic bone formation in the musculus latissimus dorsi of sheep usingβ-tricalcium phosphate scaffolds:evaluation of different seeding techniques

引用

Regenerative Biomaterials 2018年第2期5卷 77-84页

作者： Simon Spalthoff Rudiger Zimmerer Jan Dittmann Horst Kokemuller Marco Tiede Laura Flohr Philippe Korn Nils-Claudius Gellrich Philipp Jehn Department of Oral and Maxillofacial Surgery Hannover Medical SchoolCarl-Neuberg-Str.1Hannover 30625Germany Department of Conservative Dentistry Periodontology and Preventive DentistryHannover Medical SchoolCarl-Neuberg-Str.1Hannover 30625Germany

Osseous reconstruction of large bone defects remains a challenge in oral and maxillofacial *** addition to autogenous bone grafts,which despite potential donor-site mobility still represent the gold standard in reconstructive surgery,many studies have investigated less invasive alternatives such as in vitro cultivation *** study compared different types of seeding techniques on pureβ-tricalcium phosphate scaffolds in terms of bone formation and ceramic resorption in *** scaffolds loaded with autologous cancellous bone,venous blood,bone marrow aspirate concentrate or extracorporeal in vitro cultivated bone marrow stromal cells were cultured in sheep on a perforator vessel of the musculus latissimus dorsi over a 6-month *** and histomorphometric analyses revealed that scaffolds loaded with cancellous bone were superior at promoting heterotopic bone formation and ceramic degradation,with autogenous bone and bone marrow aspirate concentrate inducing in vivo formation of vital bone *** results confirm that autologous bone constitutes the preferred source of osteoinductive and osteogenic material that can reliably induce heterotopic bone formation in vivo.

关键词： heterotopic bone formation β-tricalcium phosphate bone marrow stromal cells bone marrow aspirate concentrate prevascularization ceramic degradation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pilot study on the effects of elevated air temperature and CO2 on artificially defoliated silver birch saplings

引用

Journal of Forestry Research 2018年第6期29卷 1507-1518页

作者： Valda Araminiene Iveta Varnagiryte-Kabasinskiene Vidas Stakenas Institute of Forestry Lithuanian Research Centre for Agriculture and ForestryLiepu str.1Girionys53101 Kaunas DistrictLithuania

The impacts of elevated temperature and COon young silver birch(Betula pendula Roth) saplings after 0,25, 50 or 75% artificial defoliation were assessed by measuring plant height and dry mass of aboveground compartments and roots and various morphological and physiological variables. Defoliation either increased or decreased plant growth depending on the severity of damage and the climatic treatment. At 21 °C and400 mg LCO, defoliated plants were not able to compensate for the lost foliage, but growth compensation and adaptation to the changed conditions were greater; growth of young defoliated silver birch saplings increased, which led to increased height and a tendency to enhance final aboveground and root biomass and leaf nitrogen and carbon content compared to the nondefoliated controls. Nevertheless, the short-term effect of the different climatic conditions did not result in a significant overgrowth of defoliated plants. A slight increase in temperature and COwere the most acceptable conditions for defoliated plants;however, a 4 °C increase with correspondingly higher COwas more stressful as shown by less growth in height and biomass allocation to leaves, stems and roots. The findings from the pilot experiment are more applicable to young birch trees, but stress on young trees may be reflected in future tree growth.

关键词： Biomass Betula pendula CO_2 concentration Elevated temperature Photosynthesis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

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

引用

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

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Influence of Ca addition on the dynamic and static recrystallization behavior of direct extruded flat profiles of Mg-Y-Zn alloy

引用

Journal of Magnesium and Alloys 2023年第10期11卷 3736-3748页

作者： Maria Nienaber Jan Bohlen Sangbong Yi Gerrit Kurz Karl Ulrich Kainer Dietmar Letzig Institute of Material and Process Design Helmholtz-Zentrum Hereon GmbHMax-Planck-Str.1Geesthacht 21502Germany Agnes-Miegel Str.11Bad Essen 49152Germany

This paper investigates the influence of addition of Ca in a Y-Zn-containing magnesium alloy on the dynamic and static recrystallization behaviors and reveals the formation mechanism of the quadrupole texture during thermomechanical processing. Direct extrusion of flat bands has been conducted at various process conditions to study the difference between the two alloys WZ10 and WZX100 in terms of microstructure and texture development. It can be shown that, Ca addition promotes the DRX of WZ10 alloy. During additional heat treatment,the absence of Y segregation at the grain boundaries and the associated lack of solute drag to the boundary mobility leads to a pronounced grain growth during SRX in WZX100 alloy. Furthermore, it is shown that the addition of Ca to Y-Zn is not beneficial in terms of *** is demonstrated that alloying elements can have different effects depending on the recrystallization mechanisms. Partially recrystallized microstructure is a prerequisite at the as-extruded status to form the quadrupole texture and during subsequent annealing, which stands for high formability.

关键词： Extrusion Recrystallization Magnesium alloy Mg-Y-Zn-Ca alloy Formability quadrupole texture

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：