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Recent progress in in vivo studies and clinical applications of magnesium based biodegradable implants–A review

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Journal of Magnesium and Alloys 2021年第4期9卷 1149-1166页

作者： Prithivirajan sekar Narendranath S Vijay Desai Corrosion Engineering Lab Department of Mechanical EngineeringNational Institute of Technology KarnatakaSurathkalSrinivasanagarMangalore 575025KarnatakaIndia

Biodegradable magnesium has regained great attention due to its ability to temporarily offer mechanical strength and degrade completely once the injured pathological tissue is healed.A few clinical applications of mg-based implants were reported in the last ***,the knowledge and experience is being gained continuously by studying the host response and degradation behavior of mg implant in animal models and clinical *** led to the development of commercial products emerging from Europe and Asia very *** potential of mg implants in repairing fractures at upper and lower limb of large,small animal models and humans is compared and discussed in *** addition the possible future mg implants that might treat problems concerning to urology and gynecology are reviewed.

关键词： Biodegradable Magnesium Fracture healing Translational medicine Clinical trials

Understanding the corrosion and bio-corrosion behaviour of Magnesium composites – a critical review

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Journal of Magnesium and Alloys 2024年第3期12卷 890-939页

作者： Prithivirajan sekar S.K.Panigrahi Department of Mechanical Engineering Indian Institute of Technology MadrasChennai600036India Applied Magnesium Research Center Center of Excellence in Materials and Manufacturing for Futuristic MobilityIndian Institute of Technology MadrasChennai600036India

Realising the potential of Magnesium(mg),several globally leading ventures have invested in the mg industry,but their relatively poor corrosion resistance is a never ending saga till *** corrosion and bio-corrosion behaviour of mg has gained research attention and still remains a hot topic in the application of automobile,aerospace and biomedical *** intrinsic high electrochemical nature of mg limits their utilization in diverse *** scenario has prompted the development of mg composites with an aim to achieve superior corrosion and bio-corrosion *** present review enlightens the influence of grain size(GS),secondary phase,texture,type of matrix and reinforcement on the corrosion and bio-corrosion behaviour of mg ***,the corrosion and bio-corrosion behaviour of mg composites manufactured by primary and secondary processing routes are ***,the comprehensive corrosion and bio-corrosion mechanisms of these mg composites are ***,the individual role of GS,texture and corrosive medium on corrosion and bio-corrosion behaviour of mg composites are clarified and *** challenges encountered,unanswered issues in this field are explained in detail and accordingly the scope for future research is *** review is presented from basic concrete background to advanced corrosion mechanisms with an aim of creating interest among the readers like students,researchers and industry experts from various research ***,the corrosion and bio-corrosion behaviour of mg composites are critically reviewed for the first time to:(i)contribute to the body of knowledge,(ii)foster research and development,(iii)make breakthrough,and(iv)create life changing innovations in the field of mg composite corrosion.

关键词： Corrosion Bio corrosion Magnesium alloys Magnesium composites Magnesium implants.

Simultaneous measurement of aqueous redox-sensitive elements and their species across the soil-water interface

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Journal of Environmental Sciences 2021年第4期33卷 1-10页

作者： Zhao-Feng Yuan Williamson Gustave Raju sekar Jonathan Bridge Jia-Yue Wang Wei-Jia Feng Bin Guo Zheng Chen Department of Health and Environmental Sciences Xi’an Jiaotong-Liverpool UniversityJiangsu 215123China Department of Environmental Science University of LiverpoolLiverpool L697ZXUK Department of Plant Science Tarim UniversityXinjiang 843300China Chemistry Environmental&Life SciencesUniversity of The BahamasNassauBahamas Department of Biological Sciences Xi’an Jiaotong-Liverpool UniversityJiangsu 215123China Department of Natural and Built Environment Sheffield Hallam UniversitySheffield S11WBUK Institute of Environment ResourceSoil and FertilizerZhejiang Academy of Agricultural SciencesZhejiang 310021China

The redox-sensitive elements,such as iron,manganese,sulfur,phosphorus,and arsenic,shift their speciation every millimeter(mm)across the soil-water interface in the flooded soil *** of element speciation at this high-resolution(HR)within the SWI is still *** key challenge lies in obtaining sufficient porewater samples at specific locations along the soil gradient for downstream *** with an optimized inductively coupled plasma mass spectrometry(ICP-MS)method and a HR porewater sampler,we demonstrate mm-scale element profiles mapping across the SWI in paddy *** of iron and manganese(>10 mg/L)were measured by ICP-MS in an extended dynamic range mode to avoid signal *** iron profile along the SWI generated by the ICP-MS method showed no significant difference(p<0.05)compared to that measured independently using a colorimetric ***,four arsenic(arsenite,arsenate,monomethylarsonic and dimethylarsinic acid),two phosphorus(phosphite and phosphate)and two sulfur(sulfide and sulfate)species were separated in 10 min by ion chromatography-ICP-MS with the NH_(4)HCO_(3)mobile *** verified the technique using paddy soils collected from the field,and present the mm-scale profiles of iron,manganese,and arsenic,phosphorus,sulfur species(relative standard deviation<8%).The technique developed in this study will significantly promote the measurement throughput in limited samples(e.g.100μL)collected by HR samplers,which would greatly facilitate redox-sensitive elements biogeochemical cycling in saturated soils.

关键词： Porewater Soil-water interface Arsenic Iron Sulfur Species

Hyperglycemia in COVID-19 infection without diabetes mellitus:Association with inflammatory markers

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World Journal of Clinical Cases 2023年第6期11卷 1287-1298页

作者： Harinivaas Shanmugavel Geetha Garima Singh Abinesh sekar Maya Gogtay Yuvaraj Singh George MAbraham Nitin Trivedi Department of Internal Medicine Saint Vincent HospitalWorcesterMA 01608United States Department of Hospice and Palliative Medicine University of Texas HealthSan AntonioTX 78229United States Department of Internal Medicine University of Massachusetts Chan Medical SchoolWorcesterMA 01655United States

BACKGROUND New onset hyperglycemia is common in patients with severe coronavirus disease 2019(COVID-19)*** storm due to COVID-19 infection is an essential etiology for new-onset hyperglycemia,but factors like direct severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)-induced pancreaticβ-cell failure have also been postulated to play a *** We plan to investigate further the mechanisms underlying SARS-CoV-2 infection-induced hyperglycemia,particularly the rationale of the cytokine-induced hyperglycemia hypothesis,by evaluating the association between inflammatory markers and new onset hyperglycemia in non-diabetic patients with COVID-19 *** We conducted a retrospective case-control study on adults without diabetes mellitus hospitalized for COVID-19 *** serum levels of glucose and inflammatory markers at presentation before initiation of corticosteroid were *** was defined as glucose levels≥140 mg/dL.C-Reactive protein(CRP)≥100 mg/L,ferritin≥530 ng/mL,lactate dehydrogenase(LDH)≥590 U/L,and D-dimer≥0.5 mg/L were considered *** used theχ2 test for categorical variables and the Mann-Whitney U test for continuous variables and calculated the logistic regression for *** Of the 520 patients screened,248 met the inclusion *** demographics were equally distributed between patients with hyperglycemia and those who were *** inflammatory markers in patients with or without new-onset hyperglycemia were elevated as follows:CRP(58.1%vs 65.6%,P=0.29),ferritin(48.4%vs 34.9%,P=0.14),D-dimer(37.1%vs 37.1%,P=0.76)and LDH(19.4%vs 11.8%,P=0.02).Logistic regression analysis showed LDH odds ratio(OR)=1.623(P=0.256).We observed significantly higher mortality(24.2%vs 9.1%,P=0.001;OR=2.528,P=0.024)and length of stay(8.89 vs 6.69,P=0.026)in patients with *** Our study showed no association between CRP,ferritin,LDH,D-dimer levels,and new-onset hyperg

关键词： COVID-19 Inflammatory markers Hyperglycemia C-reactive protein Mortality Severity Mechanisms Diabetes mellitus

Effect of Magnesium on the Mechanical and Bioactive Properties of Biphasic Calcium Phosphate

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Journal of Minerals and Materials Characterization and Engineering 2012年第10期11卷 982-988页

作者： Ponnusamy Kanchana Chinnathambi sekar Department of Bioelectronics and Biosensors Alagappa University Karaikudi India

Incorporation of trace elements into calcium phosphate structure is of great interest for the development of artificial bone implants. Biphasic calcium phosphate (BCP) composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have been synthesized in the presence of magnesium (5 M% - 20 M%) by gel method under physiological conditions. Crystallization of mg-BCP in the gel medium mimics the mg intake in the human body. Powder X-ray dif- fraction and Fourier transform infrared analyses confirmed that the mg doping leads to the enrichment of β-TCP phase and suppresses the HA content in BCP. Nanoindentation studies indicate a significant decrease in hardness and elastic modulus values of BCP due to mg doping. In vitro bioactivity study has confirmed the formation of apatite layer on the mg doped samples making it suitable for bone replacement. The results suggest that the optimum mg doping promotes the bioactivity which is perquisite for biomedical applications.

关键词： Biphasic Calcium Phosphate Crystal Growth X-Ray Diffraction Mechanical Properties

Use of inflammatory markers as predictor for mechanical ventilation in COVID-19 patients with stagesⅢb-Ⅴchronic kidney disease?

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World Journal of Virology 2023年第5期12卷 286-295页

作者： Harinivaas Shanmugavel Geetha Sushmita Prabhu Abinesh sekar Maya Gogtay Yuvaraj Singh Ajay K Mishra George M Abraham Suzanne Martin Department of Internal Medicine Saint Vincent HospitalWorcesterMA 01608United States Hospice and Palliative Medicine University of Texas Health-San AntonioSan AntonioTX 78201United States Division of Cardiology Saint Vincent HospitalWorcesterMA 01608United States Department of Nephrology Saint Vincent HospitalWorcesterMA 01608United States

BACKGROUND Studies have shown elevated C-reactive protein(CRP)to predict mechanical ventilation(MV)in patients with coronavirus disease 2019(COVID-19).Its utility is unknown in patients with chronic kidney disease(CKD),who have elevated baseline CRP levels due to chronic inflammation and reduced renal *** To assess whether an association exists between elevated inflammatory markers and MV rate in patients with stagesⅢb-ⅤCKD and *** We conducted a retrospective cohort study on patients with COVID-19 and stagesⅢb-Ⅴ*** primary outcome was the rate of invasive MV,the rate of noninvasive MV,and the rate of no *** analyses used unpaired t-test for continuous variables and chi-square analysis for categorical *** for variables were CRP:100 mg/L,ferritin:530 ng/mL,D-dimer:0.5 mg/L,and lactate dehydrogenase(LDH):590 U/*** 290 were screened,and 118 met the inclusion ***,D-dimer,and ferritin were significantly different among the three *** univariate analysis for invasive MV(IMV),CRP had an odds ratio(OR)-5.44;ferritin,OR-2.8;LDH,OR-7.7;D-dimer,OR-3.9,(P<0.05).The admission CRP level had an area under curve-receiver operator characteristic(AUROC):0.747 for the IMV group(sensitivity-80.8%,specificity-50%)and 0.663 for the non-IMV(NIMV)group(area under the curve,sensitivity-69.2%,specificity-53%).CONCLUSION Our results demonstrate a positive correlation between CRP,ferritin,and D-dimer levels and MV and NIMV rates in CKD *** AUROC demonstrates a good sensitivity for CRP levels in detecting the need for MV in patients with stagesⅢb-Ⅴ*** may be because of the greater magnitude of increased inflammation due to COVID-19 itself compared with increased inflammation and reduced clearance due to CKD alone.

关键词： Coronavirus disease 2019 Chronic kidney disease Inflammatory markers C-reactive protein Invasive mechanical ventilation Non-invasive mechanical ventilation