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Recent advances using equal-channel angular pressing to improve the properties of biodegradable Mg-Zn alloys

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镁合金学报(英文) 2023年第7期11卷 2260-2284页

作者： Mohammad Hashemi Reza Alizadeh Terence G.langdon Department of Materials Science and Engineering Sharif University of TechnologyTehranIran Materials Research Group Department of Mechanical EngineeringUniversity of SouthamptonSouthampton SO171BJUnited Kingdom

Magnesium alloys are of considerable current interest for use as degradable implants due to their unique properties including biodegrad-ability,biocompatibility,low density and adequate mechanical ***,there is a need to further improve these properties either by alloying or through the use of appropriate *** the different biodegradable Mg alloys now in use,the Mg-Zn series are of special interest and have been the subject of many research *** is primarily because Zn is an essential element for the human body in addition to its positive effects in improving the mechanical strength and lowering the degradation rate of the *** properties of Mg-Zn alloys may be further improved both through the addition of third and fourth alloying elements such as Ca,Ag,Sn or Sr and/or by thermo-mechanical processing where the latter is more environmentally and economically *** practice,procedures based on the application of severe plastic deformation(SPD)are especially suited to produce fine-grained microstructures with improved mechanical,degradation and cell ***-channel angular pressing(ECAP)is a popular SPD technique that has the capability of pro-ducing bulk materials that are sufficiently large for use as typical ***,this review is designed to provide a comprehensive summary of the research that has been undertaken on ECAP-processed biodegradable Mg-Zn alloys.

关键词： Bio-degradation ECAP Fine-grained microstructure Mg–Zn alloys Severe plastic deformation

Bioaccumulation of heavy metals in fishes from Taihu Lake,China

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Journal of Environmental Sciences 2007年第12期19卷 1500-1504页

作者： CHI Qiao-qiao ZHU Guang-wei Alan langdon Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China School of Science and Technology University of Waikato Hamilton New Zealand

The Cr, Zn, Cu, Cd, Pb contents were determined in Cyprinus carpio Linnaeus, Carassius auratus Linnaeus, Hypophthalmichthys molitrix and Aristichthys nobilis, which were caught from Meiliang Bay, Taihu Lake, a large, shallow and eutrophic lake of China. The results showed that：（1） the Cr, Cu, Pb, Cd contents in the edible parts of the four fish species were much lower than Chinese Food Health Criterion （1994）, but the Zn contents were higher than the Criterion; （2） Cd contents were the highest in the liver of fish, Pb contents were almost the same in all organs of fish, Cr contents mainly enriched in the skin and gonads, Zn contents were the highest in the gonad （♀）, and Cu contents were the highest in the liver; （3） the total metal accumulation was the greatest in the liver and the lowest in the muscle. The total metal accumulation was the highest in C. auratus L. This investigation indicated that fish products in Taihu Lake were still safe for human consumption, but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Zn.

关键词： fish heavy metals bioaccumulation food safety Taihu Lake

Human epidermal growth factor receptor targeted inhibitors for the treatment of ovarian cancer

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Cancer Biology & Medicine 2018年第4期15卷 375-388页

作者： Maria Bonello ANDrew Harvey Sims Simon Peter langdon Cancer Research UK Edinburgh Center and Division of Pathology Laboratory MRC Institute of Genetics and Molecular Medicine University of Edinburgh

Ovarian cancer is the second most lethal gynecological cancer worldwide and while most patients respond to initial therapy, they often relapse with resistant disease. Human epidermal growth factor receptors(especially HER1/EGFR and HER2/ERBB2) are involved in disease progression; hence, strategies to inhibit their action could prove advantageous in ovarian cancer patients,especially in patients resistant to first line therapy. Monoclonal antibodies and tyrosine kinase inhibitors are two classes of drugs that act on these receptors. They have demonstrated valuable antitumor activity in multiple cancers and their possible use in ovarian cancer continues to be studied. In this review, we discuss the human epidermal growth factor receptor family; review emerging clinical studies on monoclonal antibodies and tyrosine kinase inhibitors targeting these receptors in ovarian cancer patients; and propose future research possibilities in this area.

关键词： Tyrosine kinase monoclonal antibodies ovarian cancer inhibitors HER receptors

The thermal instability mechanism and annealed deformation behavior of Cu/Nb nanolaminate composites

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Journal of Materials Science & Technology 2023年第26期157卷 163-173页

作者： Chaogang Ding Jie Xu Debin Shan Bin Guo Terence G.langdon Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education Harbin Institute of TechnologyHarbin 150080China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China Materials Research Group Department of Mechanical EngineeringUniversity of SouthamptonSouthampton SO171BJUK

Nanoscale metallic multilayers(NMMs)have attracted significant attention owing to their enhanced me-chanical properties and excellent thermal ***,the underlying deformation mechanisms of the high-temperature annealed microstructures have not been well *** this study,the effect of annealing temperatures(500,600,700,800,and 1000℃)on the microstructural evolution and mechan-ical properties of Cu/Nb NMMs was investigated *** results show that when the anneal-ing temperature is lower than 800℃the Cu/Nb NMMs maintain their initial continuous nanolayered *** the annealing temperature reaches 1000℃,a thermal instability,driven by thermal grain boundary grooving and a Rayleigh instability,leads to the pinching offof the nanolayered structure and even a complete disintegration into an equiaxed grain *** tensile tests show that 1000℃annealed samples exhibit an enhanced strain hardening capability compared to as-rolled NMMs and this imparts superior ultimate tensile strength(∼492 MPa)and a high elongation(∼20%).TEM observations demonstrate that high-density entangled dislocations exist in the Cu-Nb interface and layers after tensile testing of the high-temperature annealed *** dislocation tangles lead to stable and progres-sive strain hardening which is the dominant factor in determining the superior combination of strength and ductility of the high-temperature annealed ***,this study offers a promising strategy for evading the strength-ductility dilemma and instead promotes a more in-depth understanding of the de-formation mechanisms of heterostructured materials.

关键词： Annealing Interfaces Mechanical properties Nanoscale metallic multilayers Thermal stability

Spatially Different Nutrient Histories Recorded by Multiple Cores and Implications for Management in Taihu Lake, Eastern China

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Chinese Geographical Science 2013年第5期23卷 537-549页

作者： CAO yanmin ZHANG Enlou Peter langdon LIU Enfeng SHEN Ji State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography&LimnologyChinese Academy of Sciences University of Chinese Academy of Sciences School of Geography University of Southampton

The Taihu Lake,a large shallow lake in the floodplain of the Changjiang(yangtze) River in the eastern China,is faced with challenging ecological problems resulting from eutrophication,which has affected the regional freshwater supply of a large *** efforts have been made to assess the nutrient evolution histories in the northern bays,little is known regarding nutrient histories in different parts across the entire lake *** this paper,we present nutrient histories for different parts of the lake based on chironomid transfer functions applied to four short cores obtained from the northern,western and eastern regions of the *** chironomid-inferred total phosphorus(CI-TP) concentrations were compared with the phosphorus concentrations obtained by using instrumental and sedimentary *** results suggest that trophic evolution histories were asynchronous throughout the lake during the past decades in response to different ecological regimes controlled by the nutrient input,wind direction and shoreline *** restoration of aquatic plants may be an effective option for the management of lake rehabilitation to ′natural′ *** the multiple factors controlling the biotic communities in such a large and complex lake,combined analyses among the multi-proxies encountered in the sediments are necessary for comprehensive insight into paleolimnological *** spatial heterogeneity in the ecological trajectories within this complicated ecosystem suggests that different management practices should be undertaken for specific lake zones in the Taihu Lake.

关键词： nutrient history chironomid multiple cores transfer function Taihu Lake

Emerging role of nuclear factor erythroid 2-related factor 2 in the mechanism of action and resistance to anticancer therapies

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Cancer Drug Resistance 2019年第3期2卷 490-515页

作者： Poornima Paramasivan Ibrahim H.Kankia Simon P.langdon yusuf y.Deeni Division of Science School of Applied SciencesAbertay UniversityDundee DD11HGUnited Kingdom Department of Biochemistry Faculty of Natural and Applied SciencesUmaru Musa Yar’adua UniversityKatsina PMB 2218Nigeria Cancer Research UK Edinburgh Centre and Edinburgh Pathology Institute of Genetics and Molecular MedicineUniversity of EdinburghCrewe Road SouthEdinburgh EH42XUUnited Kingdom

Nuclear factor E2-related factor 2(NRF2),a transcription factor,is a master regulator of an array of genes related to oxidative and electrophilic stress that promote and maintain redox ***2 function is well studied in in vitro,animal and general physiology ***,emerging data has uncovered novel functionality of this transcription factor in human diseases such as cancer,autism,anxiety disorders and diabetes.A key finding in these emerging roles has been its constitutive upregulation in multiple cancers promoting pro-survival *** survivability pathways in these studies were mostly explained by classical NRF2 activation involving KEAP-1 relief and transcriptional induction of reactive oxygen species(ROS)neutralizing and cytoprotective drug-metabolizing enzymes(phase I,II,III and 0).Further,NRF2 status and activation is associated with lowered cancer therapeutic efficacy and the eventual emergence of therapeutic ***,we and others have provided further evidence of direct NRF2 regulation of anticancer drug targets like receptor tyrosine kinases and DNA damage and repair proteins and kinases with implications for therapy *** novel finding demonstrates a renewed role of NRF2 as a key modulatory factor informing anticancer therapeutic outcomes,which extends beyond its described classical role as a ROS *** review will provide a knowledge base for these emerging roles of NRF2 in anticancer therapies involving feedback and feed forward models and will consolidate and present such findings in a systematic *** places NRF2 as a key determinant of action,effectiveness and resistance to anticancer therapy.

关键词： Cancer nuclear factor E2-related factor 2 drug resistance receptor tyrosine kinase inhibitor DNA damage and repair response targeted therapy anticancer therapeutics

Effects of heat treatment on the corrosion behavior and mechanical properties of biodegradable Mg alloys

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Journal of Magnesium and Alloys 2022年第7期10卷 1737-1785页

作者： Meysam Mohammadi Zerankeshi Reza Alizadeh Ehsan Gerashi Mohammad Asadollahi Terence G.langdon Department of Materials Science and Engineering Sharif University of TechnologyTehranIran Materials Research Group Department of Mechanical EngineeringUniversity of SouthamptonSouthampton SO171BJUnited Kingdom

Biodegradable magnesium(Mg)alloys exhibit great potential for use as temporary structures in tissue engineering *** degradable implants require no secondary surgery for their *** addition,their comparable mechanical properties with the human bone,together with excellent biocompatibility,make them a suitable candidate for fracture ***,some challenges *** degradation of the Mg-based alloys in physiological environments leads to a loss of the mechanical support that is needed for complete tissue healing and also to the accumulation of hydrogen gas bubbles at the interface of the implant and *** different methods used to improve the performance of the biodegradable Mg alloys to address these challenges,it appears that heat treatment is the most effective way to modify the microstructure and thus the corrosion behavior and mechanical properties without changing the composition or shape of the alloys.A desirable combination of corrosion and mechanical properties can be obtained through a precise control of the heat treatment *** this report,the effects of different heat treatments(T4 and T6)on the microstructure,corrosion behavior,and mechanical properties of some of the most important heat-treatable biodegradable Mg alloys(Mg-Zn,Mg-Gd,Mg-y,Mg-Nd,Mg-Al and Mg-Ag)are examined as well as new perspectives to enhance their clinical implementation.

关键词： Biodegradable implants Corrosion rate Heat treatment Mechanical properties Mg alloys

A High Frequency Boundary Element Method for Scattering by Convex Polygons with Impedance Boundary Conditions

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Communications in Computational Physics 2012年第2期11卷 573-593页

作者： S.N.Chandler-Wilde S.langdon M.Mokgolele Department of Mathematics University of ReadingWhiteknights PO Box 220Reading RG66AXU.K

We consider scattering of a time harmonic incident plane wave by a convex polygon with piecewise constant impedance boundary *** finite or boundary element methods require the number of degrees of freedom to grow at least linearly with respect to the frequency of the incident wave in order to maintain *** earlier work by Chandler-Wilde and langdon for the sound soft problem,we propose a novel Galerkin boundary element method,with the approximation space consisting of the products of plane waves with piecewise polynomials supported on a graded mesh with smaller elements closer to the corners of the *** analysis and numerical results suggest that the number of degrees of freedom required to achieve a prescribed level of accuracy grows only logarithmically with respect to the frequency of the incident wave.

关键词： Boundary integral equation method high frequency scattering convex polygons impedance boundary conditions

Spon's Landscape and External Works Price Book 2005: Free CDROM (Spons Price Books) 24

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