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Journal of Magnesium and Alloys 2024年第1期12卷 394-404页

作者： Lokesh Choudhary Parama Chakraborty Banerjee R.K.singh raman Derrek E.Lobo Christopher D.Easton Mainak Majumder Frank Witte Jörg F.Löffler Department of Mechanical and Aerospace Engineering Monash UniversityClayton CampusMelbourneVIC 3800Australia Department of Chemical and Biological Engineering Monash UniversityClayton CampusMelbourneVIC 3800Australia Nanoscale Science and Engineering Laboratory(NSEL) Bldg 37Monash UniversityClayton CampusMelbourneVIC 3800Australia CSIRO Materials Science and Engineering Bayview AvenueClaytonVIC 3168Australia Julius Wolff Institute and Berlin Brandenburg Center for Regenerative Therapies Charité–Universitätsmedizin BerlinAugustenburger Platz 113353 BerlinGermany Laboratory of Metal Physics and Technology Department of MaterialsETH Zurich8093 ZurichSwitzerland

Biodegradable implants are critical for regenerative orthopaedic procedures,but they may suffer from too fast corrosion in human-body *** necessitates the synthesis of a suitable coating that may improve the corrosion resistance of these implants without compromising their mechanical *** this study,an AZ91 magnesium alloy,as a representative for a biodegradable Mg implant material,was modified with a thin reduced graphene oxide(RGO)-calcium carbonate(CaCO_(3))composite *** analytical and in-vitro electrochemical characterization reveals that this coating significantly improves the corrosion resistance and mechanical integrity,and thus has the potential to greatly extend the related application field.

关键词： Graphene coating Biodegradable implant Hydroxyapatite Corrosion Magnesium alloy

Key Management Using Chebyshev Polynomials for Mobile Ad Hoc Networks

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China Communications 2017年第11期14卷 237-246页

作者： K.R.Ramkumar raman singh Chitkara University Chandigarh - Patiala National Highways (NH 64)Patiala - 140401 Punjab India Thapar University Patiala- 147004 Punjab India

A dedicated key server cannot be instituted to manage keys for MANETs since they are dynamic and unstable. The Lagrange's polynomial and curve fitting are being used to implement hierarchical key management for Mobile Ad hoc Networks(MANETs). The polynomial interpolation by Lagrange and curve fitting requires high computational efforts for higher order polynomials and moreover they are susceptible to Runge's phenomenon. The Chebyshev polynomials are secure, accurate, and stable and there is no limit to the degree of the polynomials. The distributed key management is a big challenge in these time varying networks. In this work, the Chebyshev polynomials are used to perform key management and tested in various conditions. The secret key shares generation, symmetric key construction and key distribution by using Chebyshev polynomials are the main elements of this projected work. The significance property of Chebyshev polynomials is its recursive nature. The mobile nodes usually have less computational power and less memory, the key management by using Chebyshev polynomials reduces the burden of mobile nodes to implement the overall system.

关键词： chebyshev polynomials interpolation secret sharing key management

Graphene coatings for corrosion resistance of nickel and copper in acidic,alkaline and neutral environments

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Journal of Materials Science & Technology 2023年第11期142卷 124-133页

作者： R.K.singh raman Abhishek Kumar Arya Kevin Tomy Faisal A Dip Evelyn Lai Saad Al-Saadi Department of Mechanical&Aerospace Engineering Monash UniversityVic 3800Australia Department of Chemical&Biological Engineering Monash UniversityVic 3800Australia

Graphene coatings have been reported to provide impressive corrosion resistance to nickel(Ni)and copper(Cu),because of remarkable characteristics of inertness and impermeablity of ***,as the earlier investigations have generally been carried out in chloride environment,and it is important to understand the performance of graphene coating also in more aggressive environments such as acids and *** study investigated the electrochemical corrosion behaviour of bare and graphene-coated(by chemical vapour deposition(CVD))Ni and Cu in 0.5 M H_(2)SO_(4),0.1 M NaCl and 0.5 M NaOH *** tests and post corrosion characterisation revealed the improvement in the corrosion resistance of Ni due to multilayer graphene coating to be similar in the three solutions,i.e.,the robustness of the barrier property of the multilayer graphene is largely unaffected by the aggressiveness of the corrosive ***,the improvement in corrosion resistance of bare Ni due to multilayer graphene is considerably greater(nearly 3 orders of magnitude)in the most aggressive of the test solutions(0.5 M H_(2)SO_(4)).The improvement is considerably less in 0.5 M NaOH because bare Ni develops a robust passive layer in highly alkaline *** improvement in corrosion resistance of bare Cu is limited(within an order of magnitude)in the three solutions because Cu develops only 1-2 layers of graphene.

关键词： CVD graphene coatings Electrochemical impedance spectroscopy(EIS) Potentiodynamic polarization(PDP) raman spectroscopy

Effect of extrusion parameters on degradation of magnesium alloys for bioimplant applications:A review

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Transactions of Nonferrous Metals Society of China 2022年第9期32卷 2787-2813页

作者： Mahdi SHIRI Hassan JAFARI raman singh Materials Engineering Department Faculty of Materials Engineering and Interdisciplinary SciencesShahid Rajaee Teacher Training University(SRTTU)16785-136 TehranIran Department of Mechanical&Aerospace Engineering and Department of Chemical Engineering 17 College Walk(Bldg 31)Monash University-Clayton Campus(Melbourne)Vic 3800Australia

Magnesium alloys,as a new generation temporary biomaterial,deserve the desirable biocompatibility and biodegradability,and also contribute to the repair of the damaged bone ***,they do not possess the required corrosion resistance in human body *** mechanical workings,such as extrusion,influence both the mechanical properties and bio-corrosion behavior of magnesium *** review aims to gather information on how the extrusion parameters(extrusion ratio and temperature)influence the bio-corrosion performances of magnesium *** effects are mainly ascribed to the alteration of extruded alloy microstructure,including final grain size and uniformity of grains,texture,and the size,distribution and volume fraction of the second *** recrystallization and grain refinement during extrusion provide a more homogeneous microstructure and cause the formation of basal texture,resulting in improved strength and corrosion resistance of magnesium *** temperature and extrusion ratio are reported as the influential factors in the *** reports reveal that the increase in extrusion ratio and/or the reduction in extrusion temperature cause a decrease in the final grain size,leading to intensification of basal texture,in parallel side of the samples with extrusion line,and to lower volume fraction and size of precipitates in magnesium *** all lead to improving the bio-corrosion resistance of the magnesium alloy implants.

关键词： magnesium alloys extrusion temperature extrusion ratio biodegradation microstructure

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Elevation, Slope Aspect and Integrated Nutrient Management Effects on Crop Productivity and Soil Quality in North-west Himalayas, India

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Journal of Mountain Science 2014年第5期11卷 1208-1217页

作者： Birendra Nath GHOSH Narinder Kumar SHARMA Nurnabi Meherul ALAM raman Jeet singh Gopal Prasad JUYAL Central Soil and Water Conservation Research and Training Institute 218 Kaulagarh Road Dehradun-248 195 Uttarakhand India

On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region（NWHR）. Under this changing scenario, elevation, slope aspect and integrated nutrient management（INM） may affect significantly soil quality and crop productivity. A study was conducted during 2009-2010 to 2010-2011 at the Ashti watershed of NWHR in a rainfed condition to examine the influence of elevation, slope aspect and integrated nutrient management（INM） on soil resource and crop productivity. Two years of farm demonstration trials indicated that crop productivity and soil quality is significantly affected by elevation, slope aspect and INM. Results showed that wheat equivalent yield（WEY） of improved technology increased crop productivity by -20%-37% compared to the conventional system. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-17%. North aspect and higher elevation increased crop productivity by 15%-25% compared to south aspect and low elevation（except paddy）. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-15%. Irrespective of slope, elevation and cropping system, the WEY increased by -30% in this region due to INMtechnology. The influence of elevation, slope aspect and INM significantly affected soil resources（SQI） and soil carbon change（SCC）. SCC is significantly correlated with SQI for conventional（R2 = 0.65＊）, INM technology（R2 = 0.81＊） and for both technologies（R2 = 0.73＊）. It is recommended that at higher elevation.（except for paddy soils） with a north facing slope, INM is recommended for higher crop productivity; conservation of soil resources is recommended for the mid hills of NWHR; and single values of SCC are appropriate as a SQI for this region.

关键词： Elevation Crop productivity Integrated nutrient management(INM) Slope aspect and soil quality

Multifunctional, Sustainable, and Biological Non-Ureolytic Self-Healing Systems for Cement-Based Materials

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Engineering 2022年第6期8卷 217-237页

作者： Mohammad Fahimizadeh Pooria Pasbakhsh Lee Sui Mae Joash Ban Lee Tan R.K.singh raman School of Engineering Monash University MalaysiaBandar Sunway 47500Malaysia School of Science Monash University MalaysiaBandar Sunway 47500Malaysia Tropical Medicine and Biology Multidisciplinary Platform Monash University MalaysiaBandar Sunway 47500Malaysia Department of Chemical Engineering&Department of Mechanical and Aerospace Engineering Monash UniversityClaytonVIC 3168Australia

Microbially induced calcium carbonate(CaCO_(3))precipitation(MICP)has been investigated as a sustain-able alternative to conventional concrete remediation methods for improving the mechanical properties and durability of concrete *** date,urea-dependent MICP is the most widely employed MICP pathway in biological self-healing concrete research as its use has resulted in efficient CaCO_(3) precipita-tion ***_(3) is a byproduct of ureolysis,and can be hazardous to cementitious structures and the health of various ***,non-ureolytic bacterial concrete self-healing systems have been developed as eco-friendly alternatives to urea-dependent self-healing ***-ureolytic pathways can improve the physical properties of concrete samples and incorporate the use of waste materials;they have the potential to be cost-effective and ***,they can be applied in terrestrial and marine *** date,research on non-ureolytic concrete self-healing systems has been scarce compared to that on ureolytic *** article discusses the advances and challenges in non-ureolytic bacterial concrete self-healing studies and highlights the directions for future research.

关键词： Self-healing concrete Mechanical properties Durability Non-ureolytic pathways Cement composite Sustainability

Physico-Chemical Characterization of Novel Epoxy Matrix System Reinforced with Recycled Short Milled Carbon Fibre

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Journal of Minerals and Materials Characterization and Engineering 2015年第5期3卷 373-389页

作者： Sagar T. Cholake Grainne Moran Yu Bai R. K. singh raman X. L. Zhao Sami Rizkalla Sri Bandyopadhyay School of Material Science and Engineering University of New South Wales Sydney Australia Mark Wainwright Analytical Centre University of New South Wales Sydney Australia Department of Civil Engineering Monash University Clayton Australia Department of Mechanical and Aerospace Engineering Monash University Clayton Australia Department of Chemical Engineering Monash University Clayton Australia Civil Engineering & Construction North Carolina State University Raleigh USA

As received recycled short milled carbon fiber (SMCF) reinforced diglycidal ether of bisphenol-A (DGEBA) epoxy matrix materials have been developed by ultra-sonication mixing of SMCF in epoxy then curing at room temperature for nine days. The SMCF with mean diameter 7.5 μm, and length 100 - 300 μm, was used at different loadings i.e. 1, 2, 3, 5 and 10 wt%. Elemental analysis, surface chemistry and crystallography of SMCF were examined using X-ray fluorescence, X-ray photoelectron spectroscopy and X-ray diffraction. Fourier Transform IR spectroscopy confirmed that both in unmodified and SMCF-modified epoxies, 99% curing was achieved. Surface microhardness study showed a slight increase with 5% and 10% SMCF addition. raman study confirms no structural change in SMCF after incorporation in epoxy. Also, a numerical modelling is implemented to correlate the density of the modified epoxy and SMCF volume fraction/distribution uniformity.

关键词： Recycled Carbon Fibre Discontinuous Reinforcement Resins Cure Behaviour

Effect of organic component(tartrate) addition on cerium nitrate's ability to inhibit corrosion of mild steel in NaCl solution

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Journal of Rare Earths 2024年第10期42卷 1995-2002页

作者： Minakshi Koundal Chhaya Sharma A.K.singh Department of Applied Science and Engineering Indian Institute of Technology RoorkeeSaharanpur Campus Department of Pulp and Paper Technology Indian Institute of Technology Roorkee Saharanpur Campus

Cerium tartrate（CeTar）,produced in this study by precipitating cerium nitrate with potassium sodium tartrate（KNaTar）,was examined as a corrosion *** loss tests show inhibition efficiency of 71.7% with Ce（NO3）3and 88.7% with CeTar inhibitor for one-month exposure to mild steel in 7 g/L NaCl *** inhibition efficiency drops to 28.6% with the fo rmer and remains around 8 7% with the latter inhibitor after six months of *** results from electrochemical testing indicate that the inhibition efficiency decreases by adding cerium ***,the cerium tartrate inhibitor demonstrates a nearly constant inhibition efficiency for up to 30 d,i.e.,≈90%.Electrochemical impedance spectroscopy（EIS） performed in these cases shows the following results:（ⅰ） with cerium nitrate,a film of iron and cerium oxide,which on prolonged exposure diminishes,and（ⅱ） with cerium tartrate,the formation of a bimetallic film（Fe-tartrate-Ce） and a mixture of cerium hydroxide and iro n oxide that protects steel for a longer *** inferences are based on the analyses of scanning electron microscopy/energydispersive X-ray analysis（SEM/EDAX）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FTIR）,X-ray photoelectron（XPS）,and raman spectroscopy results.

关键词： Cerium nitrate Cerium tartrate Corrosion inhibition Inhibitor film characterization Mild steel Rare earths

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分光光度法测定二氧化硫

黑龙江环境通报 1989年第3期13卷 32-36页

作者： D.C.Parashar V.raman M.singh 胡文庆河北省环境保护研究所

二氧化硫是一种重要的工业气体和大气污染物,它通常是使用汞盐来测定的。本文作者研究出了一种不用有毒的汞盐来测二氧化硫的方法,即用过量的重铬酸钾溶液与吗啡啉水溶液在酸性介质中相混合做为二氧化硫的吸收液。重铬酸盐中的六价铬被... 详细信息

二氧化硫是一种重要的工业气体和大气污染物,它通常是使用汞盐来测定的。本文作者研究出了一种不用有毒的汞盐来测二氧化硫的方法,即用过量的重铬酸钾溶液与吗啡啉水溶液在酸性介质中相混合做为二氧化硫的吸收液。重铬酸盐中的六价铬被二氧化硫还原成三价,过量的六价铬可用二苯基羰酰二肼测定,生成紫红色最大吸收波为540纳米的可溶性络合物,经还原作用后生成的紫红色络合物,其光度的吸收量在与控制试剂比较时,可发现与还原用的二氧化硫的浓度成正比例地下降。按比尔定律溶液中二氧化硫浓度控制范围为0.4～4μgmL^(-1)

关键词：分光光度法测定重铬酸盐二苯基羰酰二肼二氧化硫浓度比尔定律汞盐吗啡啉重铬酸钾溶液吸光度还原作用

Hydro-uvarovite from Mantle Peridotites of Naga Hills Ophiolite: A Mineral Tracer for Neo-Tethyan Mantle Wedge Metasomatism

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Acta Geologica Sinica(English Edition) 2024年第4期98卷 867-877页

作者： Anisha VERENCAR Abhishek SAHA Nilanjana SORCAR Sohini GANGULY Pankaj KUMAR Atul Kumar singh CSIR-National Institute of Oceanography Dona PaulaGoa 403004India School of Earth Ocean and Atmospheric SciencesGoa UniversityTaleigao PlateauGoa 403206India National Centre for Earth Science Studies ThiruvananthapuramKeralaIndia Inter University Accelerator Centre(IUAC) New Delhi 110067India North-Eastern Hill University ShillongMeghalaya 793022India

Hydrous Cr-bearing uvarovite garnets are rare in natural occurrences and belong to the ugrandite series and exist in binary solid solutions with grossular and andradite garnets. Here, we report the occurrence of hydrous uvarovite garnet having Cr_(2)O_(3) upto 19.66 wt% and CaO of 32.12–35.14 wt% in the serpentinized mantle peridotites of Naga Hills Ophiolite(NHO), India. They occur in association with low-Cr diopsides. They are enriched in LILE(Ba, Sr), LREEs, with fractionating LREE-MREE [avg.(La/Sm)_(N) = 2.16] with flat MREE/HREE patterns [avg.(Sm/Yb)_(N) = 0.95]. raman spectra indicate the presence of hydroxyl(OH^(–)) peaks from 3500 to 3700 cm^(-1). Relative abundances in fluid mobile elements and their close association with clinopyroxenes are suggestive of the formation of uvarovite garnets through low temperature metasomatic alteration of low-Cr diopsides by hydrothermal slab fluids. The high LREE concentration and absence of Eu anomaly in the garnet further attest to alkaline nature of the transporting slab dehydrated fluid rather the involvement of low-p H solution. The chemical characteristics of the hydroxyl bearing uvarovite hosted by the mantle peridotite of NHO deviate from the classical features of uvarovite garnet, and their origin is attributed to the fluid-induced metasomatism of the sub arc mantle wedge in a suprasubduction zone regime.

关键词： uvarovite hydroxyl metasomatic alteration low-Cr diopsides serpentinization mantle peridotite