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Kumar AM, Rajesh T, Obot IB, Bin Sharfan II, Abdulhamid MA. Water-soluble chitosan salt as ecofriendly corrosion inhibitor for N80 pipeline steel in artificial sea water: Experimental and theoretical approach. Int J Biol Macromol 2024; 254:127697. [PMID: 37918585 DOI: 10.1016/j.ijbiomac.2023.127697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/04/2023] [Accepted: 10/14/2023] [Indexed: 11/04/2023]
Abstract
Chitosan, as a proficient biopolymer, has enormous potential as an ecofriendly corrosion inhibitor (CI), but their limited solubility restricts practical applications. Herein, an eco-friendly and water-soluble chitosan salt (CS) was utilized as a green CI on N80 pipeline steel in artificial sea water. Several structural and surface analytical tools were engaged in describing the characteristics of novel CS polymer. The corrosion inhibition efficiencies of CS on steel at different concentrations were investigated through gravimetric, conventional and advanced electrochemical techniques along with the surface analyses. Tafel polarization tests specified that CS performed as mixed-type CI with prevalent anodic inhibition characteristics. At a concentration of 1000 ppm, CS provided an inhibition efficiency (IE) of 96.68 %, following physiochemical adsorptions of CS on N80 surface validated by fitting Langmuir adsorption isotherm. However, the reductions in the values of IE at high temperature specified that the CS is the temperature dependent CIs. Scanning electrochemical microscopic evaluation confirmed the formation of thin CS inhibitors films with high electrochemical stability on N80 steel in saline. The performed surface characterizations on inhibited surfaces validated the adsorption of CS on the N80 surface by forming thin inhibitor film to obstruct metal corrosion. The theoretical simulation studies using molecular dynamics and density functional theory corroborated the experimentally obtained results.
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Affiliation(s)
- A Madhan Kumar
- Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran 31261, Saudi Arabia.
| | - T Rajesh
- Interdisciplinary Research Center for Refining and Advanced Chemicals, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran 31261, Saudi Arabia
| | - I B Obot
- Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran 31261, Saudi Arabia
| | - Ibtisam I Bin Sharfan
- Sustainable and Resilient Materials Lab, Center for Integrative Petroleum Research (CIPR), College of Petroleum Engineering & Geosciences (CPG), King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Mahmoud A Abdulhamid
- Sustainable and Resilient Materials Lab, Center for Integrative Petroleum Research (CIPR), College of Petroleum Engineering & Geosciences (CPG), King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
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Hussein MA, Kumar AM, Azeem MA, Sorour AA, Saravanan S. Ti-30Nb-3Ag alloy with improved corrosion resistance and antibacterial properties for orthopedic and dental applications produced by mechanical alloying. J Mech Behav Biomed Mater 2023; 142:105851. [PMID: 37068434 DOI: 10.1016/j.jmbbm.2023.105851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/10/2023] [Accepted: 04/12/2023] [Indexed: 04/19/2023]
Abstract
Titanium alloys have gained popularity as a bioimplant material due to their biocompatibility, low modulus of elasticity, and increased strength. However, other issues, such as corrosion resistance, and infections can reduce the implant's lifespan. This paper aims to fabricate a new Ti-30Nb-3Ag at% alloy with enhanced in vitro corrosion and antibacterial properties by mechanical alloying (MA) followed by powder consolidation. XRD, SEM/EDX, and Vickers microhardness analyses were used to examine the phases compositions, microstructure, and microhardness, respectively. The in vitro corrosion performance of Ti-30Nb-3Ag alloy was inspected in a simulated body medium and artificial saliva. The alloy's antibacterial properties were evaluated in the gram-positive and negative bacterial medium. The results showed that after MA for 60 h, nanocrystalline β-Ti (BCC) and α-Ti (HCP) solid solutions were formed with crystallite sizes of 7.44 and 3.47 nm, respectively. The sintered sample exhibited densifications of 97%, with a microstructure composed of β-Ti, α-Ti, and a minor quantity of ultrafine Ti2Ag phase. The microhardness result showed that Ti-30Nb-3Ag alloy possesses HV 491.5. Ti-30Nb-3Ag alloy has a potent antibacterial capability of 85.75% and 88.81% relative to Ti-6Al-4V alloy and CP-Ti, respectively. In vitro corrosion results revealed that the Ti-30Nb-3Ag alloy exhibited the widespread passive area in the investigated anodic regions and presented the highest impedance values in comparison with the commercial alloys, confirming its improved corrosion resistance performance in both studied mediums. Ti-30Nb-3Ag alloy possibly be a competitive bioimplant material for orthopedic and dental uses owing to its enhanced biocorrosion and antibacterial properties compared to commercial Ti-6Al-4V alloy and CP-Ti.
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Affiliation(s)
- M A Hussein
- Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran, 31261, Saudi Arabia.
| | - A Madhan Kumar
- Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran, 31261, Saudi Arabia
| | - M A Azeem
- Department of Mechanical Engineering, King Fahd University of Petroleum & Minerals(KFUPM), Dhahran, 31261, Saudi Arabia
| | - A A Sorour
- Interdisciplinary Research Center for Advanced Materials, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran, 31261, Saudi Arabia; Department of Mechanical Engineering, King Fahd University of Petroleum & Minerals(KFUPM), Dhahran, 31261, Saudi Arabia
| | - S Saravanan
- Department of Bioengineering, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia
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Brickhouse TH, Yu J, Kumar AM, Dahman B. The Impact of Preventive Dental Services on Subsequent Dental Treatment for Children in Medicaid. JDR Clin Trans Res 2022:23800844221096317. [PMID: 35499130 DOI: 10.1177/23800844221096317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE The goal of this study was to use claims data linked with community-level measures to evaluate the impact of preventive services on the time to subsequent restorative, advanced restorative, and complex dental treatment among children enrolled in the Virginia Medicaid program. METHODS Four data sources were used (dental claims, eligibility files, American Community Survey, and Area Health Resource Files) for fiscal years 2011 to 2018. The outcomes of interest were time to first treatment services from birth. The treatment outcomes were basic restorative treatment, advanced restorative treatment, or complex treatment. The independent variable was a preventive service prior to a treatment service. Time-to-event curves were estimated and compared using a log-rank test. Propensity score-matched univariate and multivariate Cox proportional hazards frailty models with an inverse probability censoring weighting correction estimated hazard ratios (HRs) for treatment outcomes comparing use of preventive services while controlling for patient demographic, geospatial, and county-level socioeconomic status measures. RESULTS The analysis included 430,594 children (10,204,182 claims). A log-rank test showed significant differences (P < 0.001) between the times to treatment of those who had a preventive service and those who did not have a preventive service prior to a treatment service. Both Kaplan-Meier curves and the adjusted HR (1.88; 95% confidence interval [CI], 1.46-2.15) indicated that children without preventive services were more likely to have basic restorative treatment at an earlier age along with advanced restorative treatment (HR, 1.52; 95% CI, 1.28-1.80) and complex treatment (HR, 2.13; 95% CI, 1.68-2.61). CONCLUSIONS In a population of Medicaid-enrolled children, children who did not receive preventive services were significantly more likely to have treatment at an earlier age than those who did receive preventive services. KNOWLEDGE TRANSFER STATEMENT This study examines the impact of the utilization of preventive dental services since birth and the subsequent dental treatment for children enrolled in a dental Medicaid program. This study also examines the influence of preventive care on dental complexity of treatment for these children. Findings can inform federal and state policy planning of dental Medicaid programs as well as interventions to improve referral systems for the early use of preventive dental services and the establishment of a dental home.
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Affiliation(s)
- T H Brickhouse
- Department of Dental Public Health and Policy, School of Dentistry, Virginia Commonwealth University, Richmond, VA, USA.,Institute for Inclusion, Inquiry, and Innovation, Virginia Commonwealth University, Richmond, VA, USA
| | - J Yu
- Department of Biostatistics, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - A M Kumar
- Department of Health Behavior and Policy, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - B Dahman
- Department of Health Behavior and Policy, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
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Mansha M, Madhan Kumar A, Adesina AY, Obot I, Khan M. A novel trans-esterified water soluble hyperbranched polymer for surface protection of X60 steel: Experimental and theoretical approach. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kumar AM, Ehsan MA, Suleiman RK, Hakeem AS. AACVD processed binary amorphous NiVOx coatings on Cu substrates: Surface characterization and corrosion resistant performance in saline medium. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2021.127893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Elangovan N, Sowrirajan S, Manoj K, Kumar AM. Synthesis, structural investigation, computational study, antimicrobial activity and molecular docking studies of novel synthesized (E)-4-((pyridine-4-ylmethylene)amino)-N-(pyrimidin-2-yl)benzenesulfonamide from pyridine-4-carboxaldehyde and sulfadiazine. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130544] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Majella MG, Thekkur P, Kumar AM, Chinnakali P, Saka VK, Roy G. Effect of mobile voice calls on treatment initiation among patients diagnosed with tuberculosis in a tertiary care hospital of Puducherry: A randomized controlled trial. J Postgrad Med 2021; 67:205-212. [PMID: 34169923 PMCID: PMC8706537 DOI: 10.4103/jpgm.jpgm_1105_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Objective In India, about one third of tuberculosis (TB) patients diagnosed at tertiary hospitals are missed during a referral to peripheral health institutes for treatment. To address this, we assessed whether mobile voice call reminders to TB patients after diagnosis at a tertiary hospital decrease the proportion of "pretreatment loss to follow-up" (PTLFU), compared with the conventional paper-based referral. Design A two-group parallel-arm randomized controlled trial was conducted. Setting The study was conducted in a tertiary care hospital at Puducherry, South India. Participants All newly diagnosed TB patients, both pulmonary and extrapulmonary, who were referred for treatment from the selected tertiary care hospital and possessed a mobile phone were eligible to participate. The participants were enrolled between March 2015 and June 2016 and were randomized to study groups using the block randomization with allocation concealment. Intervention The participants in the intervention arm received standardized mobile voice calls reminding them to register for anti-TB treatment on the second and seventh day after referral in addition to the conventional paper-based referral received by the control group. Primary outcomes Patients not started on anti-TB treatment within 14 days of referral were considered as PTLFU. The outcome of PTLFU was ascertained through phone calls made on the 14th day after referral. The intention-to-treat analysis was used, and the proportion of PTLFU in the study groups and the risk difference with 95% confidence interval (CI) were calculated. Results Of the 393 patients assessed for eligibility, 310 were randomized to the intervention (n = 155) and control (n = 155) arms. In the intervention arm, 14 (9%) out of 155 were PTLFU compared with 28 (18%) of the 155 patients in the control arm. The absolute risk difference was 9% (95% CI [1.5, 16.6], P = 0.01). Conclusion Mobile voice call reminder to patients is a feasible intervention and can reduce PTLFU among referred TB patients.
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Affiliation(s)
- M G Majella
- Department of Preventive & Social Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, Tamil Nadu, India
| | - P Thekkur
- Department of Centre for Operational Research, International Union Against Tuberculosis and Lung Disease (The Union), Paris, France
| | - A M Kumar
- Department of Centre for Operational Research, International Union Against Tuberculosis and Lung Disease (The Union), Paris, France
| | - P Chinnakali
- Department of Preventive & Social Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, Tamil Nadu, India
| | - V K Saka
- Department of Pulmonary Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, Tamil Nadu, India
| | - G Roy
- Department of Preventive & Social Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, Tamil Nadu, India
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Rahman MM, Zahir MH, Arafat ME, Mazumder MAJ, Suleiman R, Kumar AM. UV‐shielding
by a polyurethane/
f
‐Oil
fly
ash‐CeO
2
protective coating. J Appl Polym Sci 2021. [DOI: 10.1002/app.49904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mohammad Mizanur Rahman
- Center of Research Excellence in Corrosion King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia
| | - Md. Hasan Zahir
- Center of Research Excellence in Renewable Energy King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia
| | - Md. Eyasin Arafat
- Department of Mechanical Engineering King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia
| | | | - Rami Suleiman
- Center of Research Excellence in Corrosion King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia
| | - A. Madhan Kumar
- Center of Research Excellence in Corrosion King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia
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Rahman MM, Suleiman R, Zahir MH, Helal A, Kumar AM, Haq MB. Multi Self-Healable UV Shielding Polyurethane/CeO 2 Protective Coating: The Effect of Low-Molecular-Weight Polyols. Polymers (Basel) 2020; 12:polym12091947. [PMID: 32872169 PMCID: PMC7565661 DOI: 10.3390/polym12091947] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 08/25/2020] [Accepted: 08/26/2020] [Indexed: 11/17/2022] Open
Abstract
We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., Mn = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of Mn 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO2 was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO2) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO2 coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO2-P) showed similar self-healing properties. The PU-11-3-3-CeO2-P coating also showed excellent UV shielding in real outdoor exposure conditions.
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Affiliation(s)
- Mohammad Mizanur Rahman
- Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia; (R.S.); (A.M.K.)
- Correspondence: (M.M.R.); (M.B.H.); Tel.: +966-13-860-7210 (M.M.R.)
| | - Rami Suleiman
- Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia; (R.S.); (A.M.K.)
| | - Md. Hasan Zahir
- Center of Research Excellence in Renewable Energy, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia;
| | - Aasif Helal
- Center of Research Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia;
| | - A. Madhan Kumar
- Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia; (R.S.); (A.M.K.)
| | - Md. Bashirul Haq
- Department of Petroleum Engineering, College of Petroleum and Geosciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
- Correspondence: (M.M.R.); (M.B.H.); Tel.: +966-13-860-7210 (M.M.R.)
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Kumar AM, Adesina AY, Hussein M, Umoren SA, Ramakrishna S, Saravanan S. Preparation and characterization of Pectin/Polypyrrole based multifunctional coatings on TiNbZr alloy for orthopaedic applications. Carbohydr Polym 2020; 242:116285. [DOI: 10.1016/j.carbpol.2020.116285] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/19/2020] [Accepted: 04/10/2020] [Indexed: 12/15/2022]
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Rahman MM, Zahir MH, Haq MB, Madhan Kumar A, Arafat ME, Rabbani MM. Silicone-enriched surface of immersed polyurethane-POSS antifouling coating. International Journal of Polymer Analysis and Characterization 2020. [DOI: 10.1080/1023666x.2020.1796106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Mohammad Mizanur Rahman
- Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
| | - Md. Hasan Zahir
- Center of Research Excellence in Renewable Energy, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
| | - Md. Bashirul Haq
- Department of Petroleum Engineering, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
| | - A. Madhan Kumar
- Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
| | - Md. Eyasin Arafat
- Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
| | - Mohammad Mahbub Rabbani
- Department of Chemistry, American International University-Bangladesh (AIUB), Dhaka, Bangladesh
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Chauhan DS, Madhan Kumar A, Quraishi M. Hexamethylenediamine functionalized glucose as a new and environmentally benign corrosion inhibitor for copper. Chem Eng Res Des 2019. [DOI: 10.1016/j.cherd.2019.07.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Mohan Kumar G, Cho H, Ilanchezhiyan P, Siva C, Ganesh V, Yuldashev S, Madhan Kumar A, Kang T. Evidencing enhanced charge-transfer with superior photocatalytic degradation and photoelectrochemical water splitting in Mg modified few-layered SnS2. J Colloid Interface Sci 2019; 540:476-485. [DOI: 10.1016/j.jcis.2019.01.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 11/25/2022]
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Madhan Kumar A, Adesina AY, Hussein MA, Ramakrishna S, Al-Aqeeli N, Akhtar S, Saravanan S. PEDOT/FHA nanocomposite coatings on newly developed Ti-Nb-Zr implants: Biocompatibility and surface protection against corrosion and bacterial infections. Mater Sci Eng C Mater Biol Appl 2019; 98:482-495. [PMID: 30813050 DOI: 10.1016/j.msec.2019.01.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 12/11/2018] [Accepted: 01/03/2019] [Indexed: 01/19/2023]
Abstract
The fabrication of bioactive polymer nanocomposite coatings with enhanced biocompatibility and surface protection has been a topic of abundant concern in orthopaedic implant applications. Herein, we electrochemically prepared a novel poly (3,4-ethylenedioxythiophene) (PEDOT) based nanocomposite coatings with different contents of fluoro hydroxyapatite (FHA) nanoparticles on a newly developed Ti-Nb-Zr (TNZ) alloy; an appropriate approach to advance the surface features of TNZ implants. FTIR, XRD, and Raman analyses of the coating confirm the successful preparation of PEDOT/FHA nanocomposite, and XPS validate the chemical interaction between FHA and PEDOT matrix. SEM and TEM examination show the uniform distribution of spherical FHA nanoparticles inside the PEDOT matrix. Hardness and contact angle measurement results showed improving in the hardness and surface wettability of the coated samples respectively. Electrochemical corrosion tests specified that the PEDOT/FHA coatings exhibit higher corrosion protection than the pure PEDOT coatings. The fabricated nanocomposite coating supports the cell adsorption and proliferation of MG-63 cells. Moreover, antibacterial studies against Gram positive and negative bacteria reveal the enhanced antibacterial performance of the coated TNZ substrates. Our results show the potential applications of PEDOT/FHA nanocomposite as a most viable coating for the orthopaedic implants.
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Affiliation(s)
- A Madhan Kumar
- Centre of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia.
| | - Akeem Yusuf Adesina
- Centre of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
| | - M A Hussein
- Centre of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, South Korea; College of Medicine, Hanyang University, Seoul, South Korea
| | - N Al-Aqeeli
- Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Sultan Akhtar
- Electron Microscopy Unit, Institute for Research & Medical Consultations, Imam Abdulrahman Bin Faisal University, Dammam 31441, Saudi Arabia
| | - S Saravanan
- Department of life science, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
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15
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Suleiman RK, Kumar AM, Sorour AA, Al-Badour FA, El Ali B. Hybrid organosiloxane material/metal oxide composite as efficient anticorrosive coatings for mild steel in a saline medium. J Appl Polym Sci 2018. [DOI: 10.1002/app.46718] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Rami K. Suleiman
- Center of Research Excellence in Corrosion; King Fahd University of Petroleum and Minerals (KFUPM); Dhahran 31261 Saudi Arabia
| | - A. Madhan Kumar
- Center of Research Excellence in Corrosion; King Fahd University of Petroleum and Minerals (KFUPM); Dhahran 31261 Saudi Arabia
| | - Ahmad A. Sorour
- Center of Research Excellence in Corrosion; King Fahd University of Petroleum and Minerals (KFUPM); Dhahran 31261 Saudi Arabia
- Mechanical Engineering Department; King Fahd University of Petroleum and Minerals (KFUPM); Dhahran 31261 Saudi Arabia
| | - Fadi A. Al-Badour
- Mechanical Engineering Department; King Fahd University of Petroleum and Minerals (KFUPM); Dhahran 31261 Saudi Arabia
| | - Bassam El Ali
- Chemistry Department; King Fahd University of Petroleum and Minerals (KFUPM); Dhahran 31261 Saudi Arabia
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Sasikumar Y, Kumar AM, Babu RS, Rahman MM, Samyn LM, de Barros ALF. Biocompatible hydrophilic brushite coatings on AZX310 and AM50 alloys for orthopaedic implants. J Mater Sci Mater Med 2018; 29:123. [PMID: 30032462 DOI: 10.1007/s10856-018-6131-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 07/09/2018] [Indexed: 06/08/2023]
Abstract
Dicalcium phosphate dihydrate (DCPD) brushite coating with flake like crystal structure for the protection of AZX310 and AM50 magnesium (Mg) alloys was prepared through chemical deposition treatment. Chemical deposition treatment was employed using Ca(NO3)2·4H2O and KH2PO4 along with subsequent heat treatment. The morphological results revealed that the brushite coating with dense and uniform structures was successfully deposited on the surface of AZX310 and AM50 alloys. The X-ray diffraction (XRD) patterns and Attenuated total reflectance infrared (ATR-IR) spectrum also revealed the confirmation of DCPD layer formation. Hydrophilic nature of the DCPD coatings was confirmed by Contact angle (CA) measurements. Moreover, electrochemical immersion and in vitro studies were evaluated to measure the corrosion performance and biocompatibility performance. The deposition of DCPD coating for HTI AM50 enables a tenfold increase in the corrosion resistance compared with AZX310. Hence the ability to offer such significant improvement in corrosion resistance for HTI AM50 was coupled with more bioactive nature of the DCPD coating is a viable approach for the development of Mg-based degradable implant materials.
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Affiliation(s)
- Y Sasikumar
- Laboratory of Experimental and Applied Physics, Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Av. Maracanã Campus 229, Rio de Janeiro, 20271-110, Brazil.
| | - A Madhan Kumar
- Center of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia.
| | - R Suresh Babu
- Laboratory of Experimental and Applied Physics, Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Av. Maracanã Campus 229, Rio de Janeiro, 20271-110, Brazil
| | - Mohammad Mizanur Rahman
- Center of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia
| | - Leandro M Samyn
- Laboratory of Experimental and Applied Physics, Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Av. Maracanã Campus 229, Rio de Janeiro, 20271-110, Brazil
| | - A L F de Barros
- Laboratory of Experimental and Applied Physics, Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Av. Maracanã Campus 229, Rio de Janeiro, 20271-110, Brazil
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Madhan Kumar A, Hussein MA, Adesina AY, Ramakrishna S, Al-Aqeeli N. Influence of surface treatment on PEDOT coatings: surface and electrochemical corrosion aspects of newly developed Ti alloy. RSC Adv 2018; 8:19181-19195. [PMID: 35539678 PMCID: PMC9080621 DOI: 10.1039/c8ra01718b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/22/2018] [Indexed: 11/21/2022] Open
Abstract
Surface treatment of metallic materials prior to the application of polymer coatings plays an important role in providing improved surface features and enhanced corrosion protection. In the current investigation, we aimed to evaluate the effect of surface treatment of newly developed TiNbZr (TNZ) alloys on the surface characteristics, including the surface topography, morphology, hydrophobicity and adhesion strength of subsequent poly(3,4-ethylenedioxythiophene) (PEDOT) coatings. The surface morphology, chemical composition, and surface roughness of both treated and coated alloys were characterized by scanning electron microscopy, energy dispersive spectroscopy, and optical profilometry, respectively. The adhesion strength of the coating was measured using a micro scratch machine. Furthermore, we also evaluated the performance of electrochemically synthesized PEDOT coatings on surface-treated TNZ alloys in terms of the surface protective performance in simulated body fluid (SBF) and in vitro bioactivity in osteoblast MG63 cells. Surface analysis findings indicated that the nature of the PEDOT coating (surface morphology, topography, wettability and adhesion strength) was intensely altered, while the surface treatment performed before electrodeposition facilitated the overall performance of PEDOT coatings as implant coating materials. The obtained corrosion studies confirmed the enhanced corrosion protection performance of PEDOT coatings on treated TNZ substrates. In vitro cell culture studies validated the improved cell adhesion and proliferation rate, further highlighting the important role of surface treatment before electrodeposition.
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Affiliation(s)
- A Madhan Kumar
- Centre of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia +966-538604818 +966-538801789
| | - M A Hussein
- Centre of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia +966-538604818 +966-538801789
| | - Akeem Yusuf Adesina
- Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals Dhahran 31261 Saudi Arabia
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University Seoul South Korea
- College of Medicine, Hanyang University Seoul South Korea
| | - N Al-Aqeeli
- Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals Dhahran 31261 Saudi Arabia
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Ilanchezhiyan P, Mohan Kumar G, Siva C, Madhan Kumar A, Yuldashev SU, Kwon YH, Kang TW. Magnetic and optical property studies on cubic Gd 3Fe 5−xCo xO 12 nanogarnets for spintronics. CrystEngComm 2018. [DOI: 10.1039/c8ce00082d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gadolinium-based rare earth garnets were processed in the form of nanostructures and studied for their optical and magnetic properties at room-temperature.
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Affiliation(s)
- P. Ilanchezhiyan
- Nano-Information Technology Academy (NITA)
- Dongguk University
- Seoul
- Republic of Korea
| | - G. Mohan Kumar
- Nano-Information Technology Academy (NITA)
- Dongguk University
- Seoul
- Republic of Korea
| | - C. Siva
- Department of Physics and Nanotechnology
- SRM University
- Kattankulathur
- India
| | - A. Madhan Kumar
- Center of Research Excellence in Corrosion
- King Fahd University of Petroleum & Minerals
- Kingdom of Saudi Arabia
| | - Shavkat U. Yuldashev
- Nano-Information Technology Academy (NITA)
- Dongguk University
- Seoul
- Republic of Korea
| | - Y. H. Kwon
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul
- Republic of Korea
| | - T. W. Kang
- Nano-Information Technology Academy (NITA)
- Dongguk University
- Seoul
- Republic of Korea
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Xing R, Latthe SS, Bhosale A, Li R, Madhan Kumar A, Liu S. A novel and facile approach to prepare self-cleaning yellow superhydrophobic polycarbonates. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.10.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ilanchezhiyan P, Mohan Kumar G, Xiao F, Poongothai S, Madhan Kumar A, Siva C, Yuldashev SU, Lee DJ, Kwon YH, Kang TW. Ultrasonic-assisted synthesis of ZnTe nanostructures and their structural, electrochemical and photoelectrical properties. Ultrason Sonochem 2017; 39:414-419. [PMID: 28732963 DOI: 10.1016/j.ultsonch.2017.05.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/05/2017] [Accepted: 05/05/2017] [Indexed: 06/07/2023]
Abstract
Colloidal zinc telluride (ZnTe) nanostructures were successfully processed through a simple and facile ultrasonic (sonochemical) treatment for photoelectronic applications. The particle-like morphological features, phase and nature of valence state of various metal ions existing in ZnTe were examined using electron and X-ray photoelectron spectroscopic tools. Raman spectroscopic measurements revealed the dominance of exciton-phonon coupling and occurrence of TeO2 traces in ZnTe through the corresponding vibrations. Optical bandgap of the ZnTe suspension was estimated to be around 2.15eV, authenticating the direct allowed transitions. The p-type electrical conductivity and charge carrier density of ZnTe were additionally estimated from the Bode, Nyquist and Mott-Schottky type impedance plots. The photoelectrical properties of ZnTe were investigated by fabricating p-ZnTe/n-Si heterostructures and studying their corresponding current-voltage characteristics under dark and white light illumination. The diodes revealed excellent rectifying behaviour with significant increase in reverse current under illumination. The stability of the devices were also affirmed through the time-dependent photoresponse characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the integrated heterojunctions. The obtained results also augment the potential of sonochemically processed ZnTe for application in photo detection and sensor related functions.
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Affiliation(s)
- P Ilanchezhiyan
- Nano-Information Technology Academy (NITA), Dongguk University, Seoul, Republic of Korea
| | - G Mohan Kumar
- Nano-Information Technology Academy (NITA), Dongguk University, Seoul, Republic of Korea.
| | - Fu Xiao
- Nano-Information Technology Academy (NITA), Dongguk University, Seoul, Republic of Korea
| | - S Poongothai
- Nano-Information Technology Academy (NITA), Dongguk University, Seoul, Republic of Korea
| | - A Madhan Kumar
- Center of Research Excellence in Corrosion, King Fahd University of Petroleum & Minerals, Saudi Arabia
| | - C Siva
- Department of Physics and Nanotechnology, SRM University, Kattankulathur, India
| | - Sh U Yuldashev
- Nano-Information Technology Academy (NITA), Dongguk University, Seoul, Republic of Korea
| | - D J Lee
- Quantum-Functional Semiconductor Research Center, Dongguk University, Seoul, Republic of Korea
| | - Y H Kwon
- Quantum-Functional Semiconductor Research Center, Dongguk University, Seoul, Republic of Korea
| | - T W Kang
- Nano-Information Technology Academy (NITA), Dongguk University, Seoul, Republic of Korea
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Mohan Kumar G, Ilanchezhiyan P, Madhan Kumar A, Yuldashev S, Kang T. Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.02.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Kumar GM, Ilanchezhiyan P, Xiao F, Siva C, Kumar AM, Yalishev V, Yuldashev SU, Kang TW. Blue luminescence and Schottky diode applications of monoclinic HfO2 nanostructures. RSC Adv 2016. [DOI: 10.1039/c6ra10644g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Schottky diodes based on metal–semiconductor (MS) and metal–insulator–semiconductor (MIS) configurations are nowadays widely regarded as key components for the realization of a number of improved electronic and optoelectronic functions.
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Affiliation(s)
- G. Mohan Kumar
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul
- Republic of Korea
| | - P. Ilanchezhiyan
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul
- Republic of Korea
| | - Fu Xiao
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul
- Republic of Korea
| | - C. Siva
- Department of Physics and Nanotechnology
- SRM University
- Chennai
- India
| | - A. Madhan Kumar
- Center of Research Excellence in Corrosion
- King Fahd University of Petroleum & Minerals
- Kingdom of Saudi Arabia
| | - Vadim Yalishev
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul
- Republic of Korea
| | - Sh. U. Yuldashev
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul
- Republic of Korea
| | - T. W. Kang
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul
- Republic of Korea
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Ilanchezhiyan P, Siva C, Kumar AM, Xiao F, Kumar GM, Kang TW. Optoelectronic characteristics of chemically processed ultra-thin InyZn1−yO nanostructures. CrystEngComm 2016. [DOI: 10.1039/c6ce00558f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Shivaramakrishna HR, Frederick A, Shazia A, Murali L, Satyanarayana S, Nair SA, Kumar AM, Moonan PK. Isoniazid preventive treatment in children in two districts of South India: does practice follow policy? Int J Tuberc Lung Dis 2015; 18:919-24. [PMID: 25199005 DOI: 10.5588/ijtld.14.0072] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
SETTING Two districts of Tamil Nadu, India OBJECTIVES To determine the proportion of household contacts aged <6 years of patients with tuberculosis (TB) with positive sputum microscopy results who initiated and completed isoniazid preventive treatment (IPT), and to determine reasons for non-initiation and non-completion of IPT. DESIGN Household visits were conducted on a random sample of adult patients registered during January-June 2012 to identify household contacts aged <6 years. RESULTS Among 271 children living with 691 index patients, 218 (80%) were evaluated and 9 (4%) were diagnosed with TB. Of 209 remaining contacts, 70 (33%) started IPT and 16 (22.9%) completed a full course of IPT. Of 139 contacts who did not start IPT, five developed TB disease. Reasons for non-initiation of IPT included no home visit by the field staff (19%) and no education about IPT (61%). Reasons for non-completion included isoniazid not provided (52%) and long duration of treatment (28%). CONCLUSION This study shows that Revised National TB Programme guidance was not being followed and IPT implementation was poor. Poor IPT uptake represents a missed opportunity to prevent future TB cases. Provision of IPT may be improved through training, improved logistics and enhanced supervision and monitoring.
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Affiliation(s)
| | - A Frederick
- Revised National TB Control Programme (RNTCP) District Tuberculosis Unit, Krishnagiri and Dharmapuri Districts, Tamilnadu
| | - A Shazia
- World Health Organization Country Office in India, New Delhi
| | - L Murali
- RNTCP State Tuberculosis Unit, Tamilnadu
| | - S Satyanarayana
- International Union Against Tuberculosis and Lung Disease, South-East Asia Regional Office, New Delhi, India
| | - S A Nair
- World Health Organization Country Office in India, New Delhi
| | - A M Kumar
- International Union Against Tuberculosis and Lung Disease, South-East Asia Regional Office, New Delhi, India
| | - P K Moonan
- Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Sharma B, Mohapatra S, Kumar AM, Deb M. Diagnostic dilemma in hookworm infection: An unusual case report. Indian J Med Microbiol 2015; 33:179-80. [DOI: 10.4103/0255-0857.148418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Madhan Kumar A, Suresh Babu R, Obot IB, Gasem ZM. Fabrication of nitrogen doped graphene oxide coatings: experimental and theoretical approach for surface protection. RSC Adv 2015. [DOI: 10.1039/c4ra13470b] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this work, we present a simple strategy of fabricating an N-doped graphene oxide coating on stainless steel for protective applications.
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Affiliation(s)
- A. Madhan Kumar
- Center of Research Excellence in Corrosion
- Research Institute
- King Fahd University of Petroleum and Minerals
- Dhahran
- Kingdom of Saudi Arabia-31261
| | - R. Suresh Babu
- Department of Printed Electronics Engineering in World Class University (WCU) Program
- Sunchon National University
- Sunchon
- Republic of Korea
| | - I. B. Obot
- Center of Research Excellence in Corrosion
- Research Institute
- King Fahd University of Petroleum and Minerals
- Dhahran
- Kingdom of Saudi Arabia-31261
| | - Zuhair M. Gasem
- Center of Research Excellence in Corrosion
- Research Institute
- King Fahd University of Petroleum and Minerals
- Dhahran
- Kingdom of Saudi Arabia-31261
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Abstract
Hybrid implant coating materials composed of at least two constituents of different chemistry, functionality, and biocompatibility have attracted attention in a wide range of biomedical applications.
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Affiliation(s)
- A. Madhan Kumar
- Centre of Research Excellence in Corrosion
- Research Institute
- King Fahd University of Petroleum and Minerals
- Dhahran
- Saudi Arabia
| | - Bharathi Suresh
- Graduate School of Biomedical Science and Engineering
- Hanyang University
- Seoul
- Korea
- College of Medicine
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering
- Hanyang University
- Seoul
- Korea
- College of Medicine
| | - Kye-Seong Kim
- Graduate School of Biomedical Science and Engineering
- Hanyang University
- Seoul
- Korea
- College of Medicine
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Madhan Kumar A, Mizanur Rahman M, Gasem ZM. A promising nanocomposite from CNTs and nano-ceria: nanostructured fillers in polyurethane coatings for surface protection. RSC Adv 2015. [DOI: 10.1039/c5ra09224h] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The balanced combination of nanostructured carbon materials and metal oxide nanoparticles has been considered as an efficient reinforcement material in developing next-generation multifunctional coatings.
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Affiliation(s)
- A. Madhan Kumar
- Center of Research Excellence in Corrosion
- Research Institute King Fahd University of Petroleum and Minerals
- Dhahran
- Saudi Arabia
| | - M. Mizanur Rahman
- Center of Research Excellence in Corrosion
- Research Institute King Fahd University of Petroleum and Minerals
- Dhahran
- Saudi Arabia
| | - Zuhair M. Gasem
- Center of Research Excellence in Corrosion
- Research Institute King Fahd University of Petroleum and Minerals
- Dhahran
- Saudi Arabia
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29
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Mohan Kumar G, Ilanchezhiyan P, Madhan Kumar A, Shabi TS, Tamil Selvan S, Suresh S, Yuldashev SU, Kang TW. Chemically-derived CuO/In2O3-based nanocomposite for diode applications. CrystEngComm 2015. [DOI: 10.1039/c5ce00853k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The potential of CuO-based nanocomposite synthesized through a facile surfactant-free wet chemical strategy has been demonstrated for photoelectronic applications.
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Affiliation(s)
- G. Mohan Kumar
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul, Republic of Korea
| | - P. Ilanchezhiyan
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul, Republic of Korea
| | - A. Madhan Kumar
- Center of Research Excellence in Corrosion
- King Fahd University of Petroleum & Minerals
- Kingdom of Saudi Arabia
| | - T. S. Shabi
- Department of Polymer Science and Engineering Zhejiang University
- Hangzhou, China
| | - S. Tamil Selvan
- Advanced Materials Processing and Analysis Center
- NanoScience Technology Center
- Materials Science Engineering
- University of Central Florida
- Orlando, USA
| | - S. Suresh
- GT-CNRS-UMI Lab
- Georgia Institute of Technology
- Metz, France
| | - Sh. U. Yuldashev
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul, Republic of Korea
| | - T. W. Kang
- Quantum-Functional Semiconductor Research Center
- Dongguk University
- Seoul, Republic of Korea
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30
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Mohan Kumar G, Madhan Kumar A, Ilanchezhiyan P, Kang TW. Solution processed n-In2O3 nanostructures for organic-inorganic hybrid p-n junctions. Nanoscale 2014; 6:11226-11231. [PMID: 25126859 DOI: 10.1039/c4nr03537b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Solution processed organic-inorganic bulk hybrid heterostructures are nowadays considered as the most promising elements to perform efficient optoelectronic functions. In this regard, In2O3 based hybrid heterostructures were fabricated using polypyrrole and their role as efficient interfacial layers was studied using polypyrrole/ZnO nanowires. The In2O3 nanostructures were synthesized through a facile wet chemical approach at an average scale of less than 10 nm in cubic phase. The presence of O and In related defects was studied through emission spectra; these were also found to exhibit their predominance in Raman measurements. The n-type characteristics and donor density value of around 10(20) cm(-3) were evaluated for the In2O3 specimens via Mott-Schottky plots. The role of In2O3 nanostructures as active/interfacial layers was then studied using the current-voltage characteristics obtained across the hybrid heterostructures made of polypyrrole/In2O3, polypyrrole/ZnO and polypyrrole/In2O3/ZnO. Organic-inorganic p-n diodes were obtained via in situ chemical polymerization, drop casting and hydrothermal routes. Cyclic voltammograms and Nyquist plots were used to study the reduction mechanism taking place in the nanostructures that actually results with the formation of metallic In, which plays a vital role in establishing the required conduction electrons. The same has been reasoned for the improved rectification characteristics observed across the diodes.
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Affiliation(s)
- G Mohan Kumar
- Quantum-Functional Semiconductor Research Center, Dongguk University, Seoul, Republic of Korea.
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Madhan Kumar A, Sudhagar P, Fujishima A, Gasem ZM. Hierarchical polymer nanocomposite coating material for 316L SS implants: Surface and electrochemical aspects of PPy/f-CNTs coatings. POLYMER 2014. [DOI: 10.1016/j.polymer.2014.08.073] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Cook R, Jones DL, Nehra R, Kumar AM, Prabhakar S, Waldrop-Valverde D, Sharma S, Kumar M. HIV Clade-C Infection and Cognitive Impairment, Fatigue, Depression, and Quality of Life in Early-Stage Infection in Northern Indians. J Int Assoc Provid AIDS Care 2013; 15:332-7. [PMID: 23722088 DOI: 10.1177/2325957413488193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
HIV disease progression is associated with declining quality of life and overall health status, although most research in this domain has been conducted among Western populations where B is the infecting clade. This study sought to determine the effects of early-stage clade-C HIV infection (CD4 count ≥400 cells/mm(3)) on neurocognitive functioning, cognitive depression, and fatigue by comparing a matched sample of HIV-positive and HIV-negative Northern Indians. This study also examined the impact of these factors on quality of life within the HIV-positive individuals. HIV-positive participants demonstrated reduced cognitive functioning, increased fatigue, and lower quality of life. Fatigue and cognitive impairment interacted to negatively impact quality of life. Results suggest that early-stage HIV clade-C-infected individuals may experience subclinical symptoms, and further research is needed to explore the benefit of therapeutic interventions to ensure optimal clinical outcomes and maintain quality of life in this vulnerable population.
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Affiliation(s)
- R Cook
- Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - D L Jones
- Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - R Nehra
- Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab, India
| | - A M Kumar
- Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - S Prabhakar
- Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab, India
| | - D Waldrop-Valverde
- Nell Hodgson Woodruff School of Nursing, Emory University, Atlanta, GA, USA
| | - S Sharma
- Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab, India
| | - M Kumar
- Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
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Winkelmann BR, Hoffmann MM, Nauck M, Kumar AM, Nandabalan K, Judson RS, Boehm BO, Tall AR, Ruaño G, März W. Haplotypes of the cholesteryl ester transfer protein gene predict lipid-modifying response to statin therapy. Pharmacogenomics J 2003; 3:284-96. [PMID: 14583798 DOI: 10.1038/sj.tpj.6500195] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cholesteryl ester transfer protein (CETP) plays a central role in high-density lipoprotein (HDL) metabolism. Single nucleotide polymorphisms (SNPs) and haplotypes in the CETP gene were determined in 98 patients with untreated dyslipidemias and analyzed for associations with plasma CETP and plasma lipids before and during statin treatment. Individual CETP SNPs and haplotypes were both significantly associated with CETP enzyme mass and activity. However, only certain CETP haplotypes, but not individual SNPs, significantly predicted the magnitude of change in HDL cholesterol (HDL-C) and triglycerides. After adjusting for covariates and multiple testing, the TTCAAA haplotype showed a gene-dose effect in predicting the HDL-C increase (P=0.03), while the TTCAAAGGG and AAAGGG haplotypes predicted a decrease in triglycerides (P=0.04 both). This is the first study to demonstrate that SNP haplotypes derived from allelic SNP combinations in the CETP gene were more informative than single SNPs in predicting the response to lipid-modifying therapy with statins.
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Affiliation(s)
- B R Winkelmann
- Cooperation Unit of Pharmacogenomics/Applied Genomics, Ruprecht Karls-University, Heidelberg, Germany.
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Abstract
V/Q imaging is often very useful in evaluating patients in whom a PE is suspected. A normal scan result can be used to exclude embolism and a high likelihood ratio scan can be used to make the diagnosis of PE. Most patients with PE do not have high likelihood ratio scans; therefore, it is important to pursue this diagnosis in patients with intermediate likelihood ratio scans and in the appropriate clinical setting for patients with the low likelihood ratio scans. In patients with parenchymal chest x-ray abnormalities who are likely to fall into the intermediate category, it can be more appropriate to use CT angiography instead of V/Q scintigraphy. This strategy probably increases the fraction of scans with high diagnostic utility.
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Affiliation(s)
- A M Kumar
- Department of Emergency Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
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35
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Kumar MS, Kode RK, Pankewycz OG, Laftavi MR, Kumar AM, Damask AM, Vora M, Tomeny MB, Ferry E, Samartino BC, Sierka D, Lingaraju RM, Fyfe B. Simulect, Neoral, Cellcept, and prednisone in kidney recipients with delayed graft function: a prospective controlled study. Transplant Proc 2001; 33:3762-3. [PMID: 11750602 DOI: 10.1016/s0041-1345(01)02592-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- M S Kumar
- Department of Transplantation, MCP Hahnemann University, Philadelphia, Pennsylvania 19102, USA
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Kumar AM, Fa K, Vankawala R, Vora M, Kode RK, Pankewycz OG, Lattavi MR, Fyfe B, Damask AM, Ferry E, Stabler S, Tomeny MB, Phillips K, Lingaraju R, Kumar MS. Simulect, calcineurin inhibitor, mycophenolate mofetil, and prednisone is more effective than OKT3, calcineurin inhibitor, hycophendate mofetil, and prednisone in African American kidney recipients in reducing acute rejections and prolonging graft survival. Transplant Proc 2001; 33:3195-6. [PMID: 11750370 DOI: 10.1016/s0041-1345(01)02359-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- A M Kumar
- Department of Transplantation, MCP Hahnemann University, Philadelphia, Pennsylvania 19102, USA
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Kumar AM, Berger JR, Eisdorfer C, Fernandez JB, Goodkin K, Kumar M. Cerebrospinal fluid 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in HIV-1 infection. Neuropsychobiology 2001; 44:13-8. [PMID: 11408787 DOI: 10.1159/000054908] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Reduced level of serotonin (5-hydroxytryptamine, 5-HT) in humans has been associated with a number of mental health and behavioral problems including depression, aggression, violence, sexual dysfunctions, sleep and eating disorders. Even though among HIV-1-infected individuals, prevalence of mental health and behavioral problems are common, their relationship with central nervous system serotonin functions is not clearly understood. This investigation was carried out to study the status of CSF 5-HT in HIV-1+ subjects (n = 21), in the early stage of infection, and HIV-1- control subjects (n = 24). Samples of CSF were obtained by lumbar puncture and were analyzed for 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA), using high-performance liquid chromatography equipped with electrochemical detector. Levels of CSF 5-HT were significantly lower in the HIV-1+ group compared to the HIV-1- group. There was no significant difference in the CSF 5-HIAA levels between the two groups. In both groups, however, there was a significant correlation between CSF 5-HT and 5-HIAA. In the HIV-1 + group, although CSF 5-HT level was significantly negatively correlated with serostatus, there was no correlation between either CSF 5-HT or 5-HIAA levels and CD4 cell number or any behavioral measures evaluated in this study, including Beck's Depression Inventory and state/trait anxiety scores. These data suggest that HIV-1 infection affects the CNS 5-HT status with no significant association with measures of depression and anxiety, at least in the early stage of infection.
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Affiliation(s)
- A M Kumar
- Department of Psychiatry and Behavioral Sciences, University of Miami School of Medicine, Miami, FL 33101, USA.
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Stephens JC, Schneider JA, Tanguay DA, Choi J, Acharya T, Stanley SE, Jiang R, Messer CJ, Chew A, Han JH, Duan J, Carr JL, Lee MS, Koshy B, Kumar AM, Zhang G, Newell WR, Windemuth A, Xu C, Kalbfleisch TS, Shaner SL, Arnold K, Schulz V, Drysdale CM, Nandabalan K, Judson RS, Ruano G, Vovis GF. Haplotype variation and linkage disequilibrium in 313 human genes. Science 2001; 293:489-93. [PMID: 11452081 DOI: 10.1126/science.1059431] [Citation(s) in RCA: 562] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Variation within genes has important implications for all biological traits. We identified 3899 single nucleotide polymorphisms (SNPs) that were present within 313 genes from 82 unrelated individuals of diverse ancestry, and we organized the SNPs into 4304 different haplotypes. Each gene had several variable SNPs and haplotypes that were present in all populations, as well as a number that were population-specific. Pairs of SNPs exhibited variability in the degree of linkage disequilibrium that was a function of their location within a gene, distance from each other, population distribution, and population frequency. Haplotypes generally had more information content (heterozygosity) than did individual SNPs. Our analysis of the pattern of variation strongly supports the recent expansion of the human population.
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Affiliation(s)
- J C Stephens
- Genaissance Pharmaceuticals, Inc., Five Science Park, New Haven, CT 06511, USA.
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McCormac AC, Fischer A, Kumar AM, Söll D, Terry MJ. Regulation of HEMA1 expression by phytochrome and a plastid signal during de-etiolation in Arabidopsis thaliana. Plant J 2001; 25:549-61. [PMID: 11309145 DOI: 10.1046/j.1365-313x.2001.00986.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The synthesis of 5-aminolevulinic acid (ALA) is the rate-limiting step for the formation of all plant tetrapyrroles, including chlorophyll and heme, and regulation of ALA synthesis is therefore critical to plant development. Glutamyl-tRNA reductase (GluTR) is the first committed enzyme of this pathway and is encoded by a small family of nuclear HEMA genes. Here, we have used transgenic Arabidopsis (Arabidopsis thaliana L. Col) lines expressing chimeric HEMA1 promoter:gusA fusion genes, combined with RNA gel blot analyses, to characterise the light-mediated regulation of the Arabidopsis HEMA1 gene during de-etiolation. HEMA1 was expressed strongly, but not exclusively, in photosynthetic tissues and was shown to be light regulated at the transcriptional level by the phytochrome family of photoreceptors acting in both the far-red high irradiance and low fluence response modes. The HEMA2 gene, which is expressed only in roots of seedlings, was not light regulated. Analysis of truncated HEMA1 promoter constructs demonstrated that a -199/+252 promoter fragment was sufficient to confer full light-responsiveness to gusA expression. This fragment contained GT-1/I-box and CCA-1 binding sites that are implicated as the light-responsive cis elements. Both the full-length and truncated HEMA1 promoters required the presence of intact chloroplasts for full expression, consistent with previous indications that light and plastid factor signals converge to co-ordinately regulate expression of photosynthesis-related nuclear genes. These results provide the most comprehensive analysis to date of the light-regulation of a tetrapyrrole biosynthetic gene and support a direct link between regulation of HEMA1 transcription and chlorophyll accumulation during seedling de-etiolation.
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Affiliation(s)
- A C McCormac
- School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK
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Kode RK, Foster CE, Kumar AM, Vankawala R, Damask AM, Fyfe BS, Seirka D, Laftavi MR, Brezin J, Pankewycz O, Chvala R, Kumar MS. Nine year experience with kidney transplantation in patients with positive hepatitis C virus antibody. Transplant Proc 2001; 33:1186-7. [PMID: 11267250 DOI: 10.1016/s0041-1345(00)02378-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- R K Kode
- Division of Transplantation, MCP Hahnemann University, Philadelphia, Pennsylvania, USA
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Kode RK, Kumar AM, Pankewycz O, Damask AM, Seirka D, Lam A, Phillips K, Ardron M, Brezin J, Chvala R, Kumar MS. Simulect induction significantly decreases CMV infection in kidney recipients compared to OKT3. Transplant Proc 2001; 33:1268-9. [PMID: 11267286 DOI: 10.1016/s0041-1345(00)02472-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- R K Kode
- Division of Transplantation, MCP Hahnemann University, Philadelphia, Pennsylvania, USA
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Chowdhury S, Kode RK, Ranganna K, Damask AM, Lam A, Fyfe B, Stabler S, Kumar AM, Tomeny MB, Kumar MS, Pankewycz O. Induction strategy using basiliximab combined with mycophenolate MMF and immediate low-dose cyclosporin is steroid sparing and more effective than OKT3. Transplant Proc 2001; 33:1057-8. [PMID: 11267189 DOI: 10.1016/s0041-1345(00)02414-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- S Chowdhury
- Division of Transplantation, MCP Hahnemann University, Philadelphia, PA, USA
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Kumar AM, Bontempo LJ, Nadel ES, Brown DF. A rare cause of congestive heart failure. J Emerg Med 2001; 20:153-7. [PMID: 11207410 DOI: 10.1016/s0736-4679(00)00305-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- A M Kumar
- Division of Emergency Medicine, Harvard Medical School, Boston, Massachusetts, USA
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Kumar AM, Murtaugh R, Brown D, Ballas T, Clancy E, Patronek G. Client donation program for acquiring dogs and cats to teach veterinary gross anatomy. J Vet Med Educ 2001; 28:73-77. [PMID: 11553874 DOI: 10.3138/jvme.28.2.73] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A donor program for procuring dogs and cats to meet the needs of anatomical instruction was initiated six years ago at Tufts University School of Veterinary Medicine. The program was initiated in order to comply with state regulations that preclude the use of shelter animals and to satisfy ethical objections of students and faculty. The donor program has successfully met the animal needs for teaching gross anatomy and, in addition, provides opportunities to integrate clinical perspectives and ethics beginning from the first year of veterinary education.
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Affiliation(s)
- A M Kumar
- Department of Biomedical Sciences, School of Veterinary Medicine, Tufts University, 200 Westboro Road, N. Grafton, MA 01536, USA.
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Affiliation(s)
- A M Kumar
- Division of Emergency Medicine, Harvard Medical School, Boston, Massachusetts, USA
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Abstract
Serotonin has been implicated to play an important role in regulating emotions and behavior, and it is well accepted that the platelet serotonergic system mirrors the presynaptic central serotonergic system. Since prevalence of psychiatric problems increases with age and women are known to be more vulnerable than men, the present investigation was carried out to study the relationship between serotonin activity and age in women. Levels of serotonin (5-hydroxytryptamine, 5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) were measured in platelets and plasma in women (n = 49) aged 40-84 years (30 women aged 40-60 years and 19 women aged 61-84 years). There was a significant age difference between the two groups (mean: 47.6 +/- 5.91 years in the younger and 73.0 +/- 6.83 years in the older women, respectively, p < 0.00001). Platelet 5-HT as well as 5-HIAA levels were significantly higher in older women as compared to those in the younger women (89.41 +/- 21.95 ng/10(8) platelets in younger vs. 112.9 +/- 36.07 in older women, p < 0.02, and 1.20 +/- 1.10 in younger vs. 2.19 +/- 1.88 ng/10(8) platelets in older women, p < 0.05, respectively). Pearson correlation coefficients determined in the combined group (n = 49) showed a significant positive correlation between platelet 5-HT and age (r = 0.31, p < 0.03). Plasma 5-HT levels on the other hand were lower in older women compared to those in the younger women (4.50 +/- 3.20 in younger vs. 1.04 +/- 1.28 ng/ml plasma in older women, p < 0.0001) and a significant negative correlation was observed between plasma 5-HT and age (r = -0.44, p < 0.002). Plasma 5-HIAA concentration did not differ between the two groups. Platelet 5-HT levels in the younger group were independent of ethnicity. Since high serotonin activity has also been associated with psychiatric problems, our results of increased concentration of platelet 5-HT as well as 5-HIAA with age may have implications in predisposing aging women to behavioral/psychiatric problems.
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Affiliation(s)
- A M Kumar
- Department of Psychiatry and Behavioral Sciences, University of Miami School of Medicine, Fla. 33101, USA
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Abstract
Transplantation of progenitor cells for regeneration of islet cells could prove invaluable in the treatment of diabetes mellitus. This study provides evidence that in rats maintained on a copper-deficient diet containing the copper-chelating agent tetraethylenepentamine pentahydrochloride, regeneration of single alpha and beta endocrine cells in the ductules and acinar tissue of the adult rat pancreata occurred. These regenerated cells both in the ductules and acinar tissue stained positive for glucagon and insulin similar to cells within the islets and in addition to being reactive to proliferative cellular nuclear antigen, an intracellular marker of active proliferation. In contrast, the control group pancreata did not show any evidence of islet regeneration, proliferation, or proliferative cellular nuclear antigen reactivity pre- or posttransplantation. Transplantation of digested pancreatic tissues from the copper-deficient group into the spleen of syngeneic diabetic rats reversed diabetes, and this was confirmed histologically by demonstrating cells within ductules that stained positively for insulin. This study concludes that copper deprivation contributes to the neogenesis of pancreatic alpha and beta cells in the ductules and acinar tissue of adult pancreas in rat model and that transplanted stem cells maintain their functional capacity in the recipient after transplantation.
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Affiliation(s)
- I H Al-Abdullah
- Department of Surgery, MCP-Hahnemann University, Philadelphia, Pennsylvania, USA.
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Abstract
OBJECTIVE The purpose of this study was to find whether nefazodone, effective in adult depression, might be similarly improve symptoms of adolescent depression. Secondary purpose was to relate platelet serotonin content to response, and to find if nefazodone's effect on platelet content was similar to that of the SSRIs. METHOD 10 adolescents meeting DSMIV criteria for major depression received up to 400 mg of nefazodone for an eight week period. Response was assessed at baseline, 1, 2, 4, and 8 weeks by BDI and HDRS; platelet serotonin (5HT) content was obtained at baseline and final visit (for two dropouts, this was done at last visit, i.e., week 4). RESULTS In LOCF analysis, significant improvement was found in both HDRS (20.9 to 8.9, p = .01) and BDI (24.6 to 10.2, p = .01). Eight of nine patients with available data showed increases in platelet 5HT content (.02). In seven patients of eight completers with available data, there was a nonsignificant trend for patients with platelet 5HT baseline greater than 30 ng/10(8) platelets to show a greater change in HDRS than those with a baseline of less than 30 ng/10(8) platelets (p = .07). CONCLUSIONS Further double-blind study of nefazodone in adolescent depression is indicated; nefazodone appears to increase platelet 5HT content.
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Affiliation(s)
- P J Goodnick
- Department of Psychiatry & Behavioral Science, University of Miami School of Medicine, Miami, Florida 33136, USA
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Kumar AM, Söll D. Antisense HEMA1 RNA expression inhibits heme and chlorophyll biosynthesis in arabidopsis. Plant Physiol 2000; 122:49-56. [PMID: 10631248 PMCID: PMC58843 DOI: 10.1104/pp.122.1.49] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/1999] [Accepted: 09/23/1999] [Indexed: 05/20/2023]
Abstract
5-aminolevulinic acid (ALA) is a precursor in the biosynthesis of tetrapyrroles including chlorophylls and heme. The formation of ALA involves two enzymatic steps which take place in the chloroplast in plants. The first enzyme, glutamyl-tRNA reductase, and the second enzyme, glutamate-1-semialdehyde-2,1-aminomutase, are encoded by the nuclear HEMA and GSA genes, respectively. To assess the significance of the HEMA gene for chlorophyll and heme synthesis, transgenic Arabidopsis plants that expressed antisense HEMA1 mRNA from the constitutive cauliflower mosaic virus 35S promoter were generated. These plants exhibited varying degrees of chlorophyll deficiency, ranging from patchy yellow to total yellow. Analysis indicated that these plants had decreased levels of chlorophyll, non-covalently bound hemes, and ALA; their levels were proportional to the level of glutamyl-tRNA reductase expression and were inversely related to the levels of antisense HEMA transcripts. Plants that lacked chlorophyll failed to survive under normal growth conditions, indicating that HEMA gene expression is essential for growth.
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Affiliation(s)
- A M Kumar
- Department of Molecular Biophysics and Biochemistry, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8114, USA
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