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Investigation into machining performance of microstructurally engineered in-situ particle reinforced magnesium matrix composite

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Journal of Magnesium and Alloys 2023年第3期11卷 916-935页

作者： S.K.Sahoo b.n.Sahoo S.K.Panigrahi Department of Mechanical Engineering Indian Institute of Technology MadrasChennai 600036India Applied Magnesium Research Group Center of Excellence in Materials and Manufacturing for Futuristic MobilityIndian Institute of Technology MadrasChennai 600036India Department of Mechanical Engineering Sardar Vallabhbhai National Institute of TechnologySurat 395007India

Magnesium and magnesium in-situ composites have significant potential in the application of design and manufacturing for automotive and aerospace industries because of their high specific strength and reduced fuel *** there are many challenges for machining of Mg based alloys and composites because of the high tendency of fire and *** challenges can be minimized through microstructural *** this present study,the machining performances of AZ91 Mg alloy and in-situ hybrid TiC+Tib_(2)reinforced AZ91 metal matrix composite was *** effectβ-Mg_(17)Al_(12)phases and grain refinement with and without in-situ particles on machinability were studied through microstructural engineering via aging and friction stir *** end milling operation was carried out at different cutting speeds ranging from 25 mm/min to 90 mm/min under dry environment by using an AlTin-coated tungsten carbide *** optimum cutting speed for machining was found to be 75 mm/min based on the surface roughness values of all conditioned *** base material with dendritic microstructure was found to have poor machinability in terms of inadequate surface finish and edge-burrs *** combined effect of in-situ TiC+Tib_(2)particles addition and grain refinement enhanced the machining performance of the material with superior surface finish,negligible edge-burr formation and better tool wear *** influence of in-situ TiC+Tib_(2)particles,β-Mg_(17)Al_(12)phases and grain refinement on machining characteristics are explained based on the tool wear mechanisms,chip behavior and machining induced affected zone.

关键词： Magnesium In-situ composite End-milling Tool wear Chip morphology

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Microstructural, mechanical and corrosion characterization of an as-cast Mg-3Zn-0.4Ca alloy for biomedical applications

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Journal of Magnesium and Alloys 2020年第2期8卷 510-522页

作者： n.Pulido-Gonzalez b.Torres P.Rodrigo n.Hort J.Rams Department of Applied Mathematics Materials Science and Engineering and Electronics Technology.ESCETRey Juan Carlos UniversityC/Tulipan s/n28933 MdstolesMadridSpain Magnesium Innovation Centre Helmholtz-Zentrum Geesthacht21502 GeesthachtGermany

The as-cast Mg-3Zn-0.4Ca alloy shows a great potential to be used in biomedical applications due to its composition,mechanical properties and *** and Ca appear naturally in the organism accomplishing vital *** alloy consists of an a-Mg matrix and a eutectic composed of *** eutectic product enhances the mechanical properties of the studied alloy,causing strengthening and providing superior hardness *** this alloy,cracks initiate at the intermetallic compounds and progress through the matrix because of the open network formed by the *** to the corrosion results,the eutectic product presents a noble potential compared to the a-Mg *** this reason,the corrosion progresses preferentially through the matrix,avoiding the(α-Mg+Ca2Mg6Zri3)eutectic product,when the alloy is in direct contact to Hank's solution.

关键词： Mg-Zn-Ca alloys biomaterials biodegradable implants nanoindentation Three-point bending test Corrosion behaviour

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Response of testicular antioxidant enzymes to hexachlorocy clohexane is species specific

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Asian Journal of Andrology 2002年第3期4卷 191-194页

作者： Luna Samanta G.b.n. Chainy biochemistry Unit & ICAbPS Department of Zoology Utkal University Bhubaneswar-751004 IndiaBiochemistry Unit & ICABPS Department of Zoology Utkal University Bhubaneswar-751004 India

Aim: To find out whether the response of testicular oxidative stress parameters to hexachlorocyclohexane (HCH) is species specific. Methods: In rats and mice (n=5 in each group), HCH was administered at a dose of 20 mg/kg/day intraperitoneally for 30 days in 0.1 ml of refined groundnut oil. The control groups received equal volume of the vehicle. Animals were sacrificed 24 hours after the last injection and various oxidative stress parameters were measured immediately. Results: The level of both endogenous as well as FeSO_4 and ascorbic acid-stimulated lipid peroxidation was increased significantly in the HCH-treated rats, whereas the pattern was just the reverse in case of mice. Although the level of H_2O_2 content increased in response to HCH in both groups, a totally different trend was observed for the activity of the principal H_2O_2-metabolising enzyme, catalase. In case of rats, a significant decline in the activity of catalase was recorded in response to HCH whereas a sharp augmentation in the enzyme activity was noticed in mice. Similarly, the decreased activity of superoxide dismutase observed in rats remained unaltered in mice. Conclusion: HCH induces oxidative stress in the testis of both rats and mice. However, the pattern of response of testicular oxidative stress parameters seems to be species specific.

关键词： hexachlorocyclohexane rat testes lipid peroxidation antioxidant defence

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Investigating the UV-excess in Star Clusters with n-body Simulations:Predictions for Future CSST Observations

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Research in Astronomy and Astrophysics 2022年第9期22卷 176-201页

作者： Xiaoying Pang Qi Shu Long Wang M.b.n.Kouwenhoven Department of Physics Xi’an Jiaotong-Liverpool UniversitySuzhou 215123China Shanghai Key Laboratory for Astrophysics Shanghai Normal UniversityShanghai 200234China School of Physics and Astronomy Sun Yat-sen UniversityZhuhai 519082China Department of Astronomy School of ScienceThe University of TokyoTokyo 113-0033Japan RIKEn Center for Computational Science KobeHyogo 650-0047Japan

We study the origin of the UV-excess in star clusters by performing n-body simulations of six clusters with n = 10 k and n = 100 k(single stars & binary systems) and metallicities of Z = 0.01, 0.001 and 0.0001, using PETAR. All models initially have a 50% primordial binary fraction. Using Galev nb we convert the simulated data into synthetic spectra and photometry for the China Space Station Telescope(CSST) and Hubble Space Telescope(HST). From the spectral energy distributions we identify three stellar populations that contribute to the UVexcess:(1) second asymptotic giant branch stars, which contribute to the UV flux at early times;(2) naked helium stars and(3) white dwarfs, which are long-term contributors to the FUV spectra. binary stars consisting of a white dwarf and a main sequence star are cataclysmic variable(CV) candidates. The magnitude distribution of CV candidates is bimodal up to 2 Gyr. The bright CV population is particularly bright in FUV-nUV. The FUV-nUV color of our model clusters is 1–2 mag redder than the UV-excess globular clusters in M87 and in the Milky Way. This discrepancy may be induced by helium enrichment in observed clusters. Our simulations are based on simple stellar evolution;we do not include the effects of variations in helium and light elements or multiple stellar populations. A positive radial color gradient is present in CSST nUV-y for main sequence stars in all models with a color difference of 0.2–0.5 mag, up to 4 half-mass radii. The CSST nUV-g color correlates strongly with HST FUV-nUV for nUV-g > 1 mag, with the linear relation FUV-nUV =(1.09 ± 0.12) ×(nUV-g) +(-1.01 ± 0.22). This allows for conversion of future CSST nUV-g colors into HST FUV-nUV colors, which are sensitive to UV-excess features. We find that CSST will be able to detect UVexcess in Galactic/extragalactic star clusters with ages >200 Myr.

关键词： methods:numerical (stars:)binaries:general stars:kinematics and dynamics

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The Fibrillar Matrix:novel Avenues for breast Cancer Detection and Treatment

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Engineering 2021年第10期7卷 1375-1380页

作者： Rasha Rezk Raquel Marín-García Annica K.b.Gad Weston Park Cancer Centre Department of Oncology and MetabolismThe Medical SchoolThe University of SheffieldSheffield S102RXUnited Kingdom Department of Engineering University of CambridgeCambridge CB21PZUnited Kingdom Madeira Chemistry Research Center University of MadeiraFunchal 9020105Portugal

breast cancer is marked by large increases in the protein fibers around tumor *** fibers increase the mechanical stiffness of the tissue,which has long been used for tumor diagnosis by manual *** research in bioengineering has led to the development of novel biomaterials that model the mechanical and architectural properties of the tumor microenvironment and can be used to understand how these cues regulate the growth and spread of breast ***,we provide an overview of how the mechanical properties of breast tumor tissues differ from those of normal breast tissue and noncancerous *** also describe how biomaterial models make it possible to understand how the stiffness and viscosity of the extracellular environment regulate cell migration and breast cancer *** highlight the need for biomaterial models that allow independent analysis of the individual and different mechanical properties of the tumor microenvironment and that use cells derived from different regions within *** models will guide the development of novel mechano-based therapies against breast cancer metastasis.

关键词： breast cancer Tissue stiffness Cancer metastasis Cell migration bioengineered scaffold Viscosity

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Arsenic and sulfur nanoparticle synthesis mimicking environmental conditions of submarine shallow-water hydrothermal vents

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Journal of Environmental Sciences 2022年第1期34卷 301-312页

作者： Vicente Durán-Toro Kurosch Rezwan Solveig I.bühring Michael Maas MARUM–Center for Marine Environmental Sciences University of BremenBremen 28359Germany Advanced Ceramics University of BremenBremen 28359Germany MAPEX-Center for Materials and Processes University of BremenBremen 28359Germany

Arsenic and sulfur mineralization is a natural phenomenon occurring in hydrothermal systems where parameters like temperature and organic matter(OM)can influence the mobilization of the toxic metalloid in marine *** the present study we analyze the influence of temperature and OM(particularly sulfur-containing additives)on As and S precipitation based on the recent discovery of As-rich nanoparticles in the hydrothermal system near the coast of the Greek island *** this end,we experimentally recreate the formation of amorphous colloidal particles rich in As and S via acidification(pH 3–4)of aqueous precursors at various *** higher temperatures,we observe the formation of monodisperse particles within the first 24 h of the experiment,generating colloidal particles with diameters close to 160 *** S:As ratio and particle size of the synthetized particles closely correlates with values for As_(x)S_(y)particles detected in the hydrothermal system off ***,organic sulfur containing additives(cysteine and glutathione,GSH)are a key factor in the process of nucleation and growth of amorphous colloidal As_(x)S_(y)particles and,together with the temperature gradient present in shallow hydrothermal vents,dictate the stabilization of As-bearing nanomaterials in the *** on these findings,we present a simple model that summarizes our new insights into the formation and mobility of colloidal As in aquatic *** this context,amorphous As_(x)S_(y)particles can present harmful effects to micro-and macro-biota not foreseen in bulk As material.

关键词： biomineralization Milos Hydrothermal vent Arsenic Sulfur nanoparticles Ecotoxicology

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Enhanced green emission from La＿(0.4)F＿3:Ce＿(0.45),Tb＿(0.15)/TiO＿2 core/shell structure

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Journal of Rare Earths 2015年第1期33卷 20-26页

作者： T.K.Srinivasan b.S.Panigrahi n.Suriyamurthy P.K.Parida b.Venkatraman Indira Gandhi Centre for Atomic Research Kalpakkam–603102 India

nano sized La0.4F3：Ce0.45,Tb0.15（core）, La0.4F3：Ce0.45,Tb0.15（Ti O2）（core） shell, La0.55F：Ce0.45, and La0.85F3：Tb0.15 particles were synthesized by adopting co-precipitation technique in acidic environment and coated with Ti O2 to form a core-shell structure by adopting a mechanical dispersion method at room temperature. The synthesized materials were characterized using X-ray diffraction（XRD）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FTIR）, ultraviolet-visible spectroscopy（UV-Vis） absorption, photoluminescence and lifetime spectroscopy. The crystal structure of La0.4F3：Ce0.45,Tb0.15 remained the same as La F3 after being doped with Ce and Tb ions but with a slight decrease in the lattice parameter. TEM image confirmed the formation of a core-shell structure. The La0.4F3：Ce0.45,Tb0.15/Ti O2 exhibited Tb3＋ fluorescence enhancement by a factor of 1.76. Scintillation from the synthesized materials was also observed under X-ray excitation.

关键词： core-shell cerium terbium luminescence lanthanum fluoride scintillation rare earths

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Metapopulation approach for landscape level management of western tarnished plant bug,Lygus hesperus,in Texas( Hemiptera,Miridae)

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植物保护学报 2014年第6期41卷 761-768页

作者： Parajulee Megha n Shrestha Ram b Texas A & M University System AgriLife Research and Extension Center

Insect source-sink dynamics are vital to ecologically intensive pest management. Maintaining sink plant hosts,or "trap crops",and destroying alternate hosts or breeding places adjacent to the field crop are effective pest management strategies for some arthropods. However,determining whether a host acts as a source or a sink is challenging, especially when the pest species is highly mobile and polyphagous. The western tarnished plant bug,Lygus hesperus,is highly polyphagous,and can utilize >300 hosts. Its presence has been documented in 26 roadside weed hosts in the Texas High *** studies demonstrated that L. hesperus prefer alfalfa over cotton and several alternate weed hosts.A four-year project involved surveying and sampling for L. hesperus in the agricultural landscapes of several sub-regions of the southwestern United States,including the Texas High Plains. In Texas,geographic information of the landscape vegetation complex was compiled from a 150 km radius in the Texas High Plains. In one study,fifty irrigated cotton fields representing the crop diversity within this region were sampled via sweep-net for 10 weeks. This effort also included sampling of up to six noncotton insect habitats within a 3 km radius of each field. Seasonal average L. hesperus abundance data were regressed with 27 field characteristics( variables),including habitat-specific land cover,distance between focal cotton fields and non-cotton habitats,longitude,latitude,elevation,habitat heterogeneity index,and several environmental / ecological variables. Significant variables were selected using a stepwise regression at 15% probability rate. A 10-parameter linear model explained 93% of the variation in the data. Major parameters contributing significantly to variation in L. hesperus abundance in cotton were corn and sunflower acreages,focal cotton field distances from several non-cotton hosts,and habitat heterogeneity index. In addition,field marking-and-capture studies were cond

关键词： western tarnished plant bug cotton IPM ecological pest management alternate host management

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Electrical properties of na_(2)Pb_(2)R_(2)W_(2)Ti_(4)V_(4)O_(30)(R=Dy,Pr)ceramics

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Journal of Advanced Ceramics 2013年第2期2卷 112-118页

作者： Piyush R.DAS b.n.PARIDA R.PADHEE R.n.P.CHOUDHARY Department of Physics Institute of Technical Education&ResearchSiksha‘O’Anusandahan UniversityKhandagiriBhubaneswar 751030OdishaIndia

The polycrystalline samples of complex tungsten bronze(Tb)na_(2)Pb_(2)R_(2)W_(2)Ti_(4)V_(4)O_(30)(R=Dy,Pr)compounds were prepared by solid-state reaction ***-temperature preliminary structural studies confirm the formation of the compounds in the orthorhombic crystal *** studies of electrical properties of the materials using complex impedance spectroscopy technique exhibit that the impedance and related parameters are strongly dependent upon temperature and microstructure(bulk,grain boundary,etc).An observation of negative temperature coefficient of resistance(nTCR)suggests the materials have semiconducting *** variation of AC conductivity with temperature shows a typical Arrhenius behavior of the *** the samples obey Jonscher’s universal power *** existence of hopping mechanism in the electrical transport processes in the system with non-exponential type of conductivity relaxation is confirmed by electrical modulus analysis.

关键词： ceramics impedance spectroscopy electrical properties ferroelectricity microstructure

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SERS-based lateral flow immunoassay of troponin I by using gapenhanced Raman tags

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nano Research 2019年第2期12卷 413-420页

作者： boris n. Khlebtsov Daniil n. bratashov nadezhda A. byzova boris b. Dzantiev nikolai G. Khlebtsov Institute of biochemistry and Physiology of Plants and Microorganisms Russian Academy of Sciences Saratov 410049 Russia Saratov State University Saratov 410012 Russia A. n. bach Institute of biochemistry Research Centre of Biotechnology Russian Academy of Sciences Moscow 119071 Russia

The lateral flow immuno assay (LFIA) has emerged as a powerful tool for rapid scree ning owing to its simplicity and flexibility for detection of various biomarkers. However, conventional LFIA strips have several disadvantages, including limits in quantitative analysis and low sensitivity. Here we developed a novel surface-e nhanced Rama n scatteri ng LFIA based on non spherical gap-e nhanced Raman tags (GERTs), with Raman molecules (RMs) embedded in a 1-nm gap between Au nanorod core and Au shell. Such tags have a strong and uniform surface-enhanced Rama n scattering (SERS) resp on se, an order of mag nitude higher than that of other comm on SERS tags such as Au nano rods, nano stars, Au nano shells with surface-adsorbed RMs, or spherical GERTs with embedded RMs. The feasibility of the tags was dem on strated by the semiqua ntitative and sen sitive detecti on of the heart disease biomarker cardiac tropo nin I (cTnI). GERTs were conjugated with mono clonal antibodies and used for LFIA in the same way as ordinary functionalized colloidal gold. The presenee of the target antigen, cTnI, was identified by Raman microscopy mapping of the test zone. With the SERS-based LFIA, the limit of cTnI detection was about 0.1 ng/mL. This value is within the diagnostic range of cTnI in the blood serum of patients with heart infarction and is 30 times lower than that of the colorimetric LFIA test using the same antibodies and either GERTs or colloidal gold as labels.

关键词： surface-enhanced Raman scattering (SERS) lateral flow immunoassay Au core/shell nanorods gap-enhanced Raman tags cardiac troponin I

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