Displaying publications 1 - 20 of 54 in total

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  1. Viswanathan, R., Ramesh, S., Kamesh Kumar, D., Elango, N.
    MyJurnal
    This paper focuses on examining the ‘cutting zone temperature’ while performing turning operation
    on AZ91Mg alloy using cemented carbide tools. The regression model is developed by using the RSM
    techniques based on experimental results. It is revealed that the cutting speed (v) is the most dominant
    factor affecting cutting zone temperature. The developed models of cutting zone temperature sufficiently
    map within the range of the turning conditions considered. The adequacy and accuracy of the regression
    equation is justified through ANOVA. It is found that the optimal combinations of machining parameters
    minimize the cutting temperature.
  2. Vikneswaran R, Syafiq MS, Eltayeb NE, Kamaruddin MN, Ramesh S, Yahya R
    PMID: 26046495 DOI: 10.1016/j.saa.2015.05.087
    Copper ion recognition and DNA interaction of a newly synthesized fluorescent Schiff base (HPyETSC) were investigated using UV-vis and fluorescent spectroscopy. Examination using these two techniques revealed that the detection of copper by HPyETSC is highly sensitive and selective, with a detection limit of 0.39 μm and the mode of interaction between HPyETSC and DNA is electrostatic, with a binding constant of 8.97×10(4) M(-1). Furthermore, gel electrophoresis studies showed that HPyETSC exhibited nuclease activity through oxidative pathway.
  3. Tan CY, Ramesh S, Aw KL, Yeo WH, Hamdi M, Sopyan I
    Med J Malaysia, 2008 Jul;63 Suppl A:87-8.
    PMID: 19024997
    The sintering behaviour of synthesized HA powder that was calcined at various temperatures ranging from 700 degrees C to 1000 degrees C was investigated in terms of phase stability, bulk density, Young's modulus and Vickers hardness. The calcination treatment resulted in higher crystallinity of the starting HA powder. Decomposition of HA phase to form secondary phases was not observed in all the calcined powders. The results also indicated that powder calcination (up to 900 degrees C) prior to sintering has negligible effect on the sinterability of the HA compacts. However, powder calcined at 1000 degrees C was found to be detrimental to the properties of sintered hydroxyapatite bioceramics.
  4. Soudagar MEM, Kiong TS, Jathar L, Nik Ghazali NN, Ramesh S, Awasarmol U, et al.
    Chemosphere, 2024 Apr;353:141540.
    PMID: 38423144 DOI: 10.1016/j.chemosphere.2024.141540
    The development of algae is seen as a potential and ecologically sound approach to address the increasing demands in multiple sectors. However, successful implementation of processes is highly dependent on effective growing and harvesting methods. The present study provides a complete examination of contemporary techniques employed in the production and harvesting of algae, with a particular emphasis on their sustainability. The review begins by examining several culture strategies, encompassing open ponds, closed photobioreactors, and raceway ponds. The analysis of each method is conducted in a systematic manner, with a particular focus on highlighting their advantages, limitations, and potential for expansion. This approach ensures that the conversation is in line with the objectives of sustainability. Moreover, this study explores essential elements of algae harvesting, including the processes of cell separation, dewatering, and biomass extraction. Traditional methods such as centrifugation, filtration, and sedimentation are examined in conjunction with novel, environmentally concerned strategies including flocculation, electro-coagulation, and membrane filtration. It evaluates the impacts on the environment that are caused by the cultivation process, including the usage of water and land, the use of energy, the production of carbon dioxide, and the runoff of nutrients. Furthermore, this study presents a thorough examination of the current body of research pertaining to Life Cycle Analysis (LCA) studies, presenting a perspective that emphasizes sustainability in the context of algae harvesting systems. In conclusion, the analysis ends up with an examination ahead at potential areas for future study in the cultivation and harvesting of algae. This review is an essential guide for scientists, policymakers, and industry experts associated with the advancement and implementation of algae-based technologies.
  5. Shan L, Tan CY, Shen X, Ramesh S, Kolahchi R, Hajmohammad MH, et al.
    Materials (Basel), 2022 Dec 15;15(24).
    PMID: 36556764 DOI: 10.3390/ma15248959
    Lightweight aluminum alloy components are often used to manufacture a variety of engineering components in many industries. In recent years, researchers have studied the effect of improving the mechanical properties of metal alloys by incorporating nano-carbon into its structure. In this study, the effect of the addition of 0.2, 0.5, and 1 wt% of multi-walled carbon nanotubes (MWCNTs) on the stress-strain behavior and creep phenomenon of an A356 aluminum alloy were studied. The effect of nickel coating on 0.2 wt% MWCNTs was also investigated. Samples were prepared using the stir-casting method. The results revealed that the grain size became finer when MWCNT nano-particulates were introduced. Although the MWCNTs were distributed homogeneously in the A356 matrix, as confirmed by FESEM analysis, there were some agglomerations observed in a specific area with dimensions smaller than 100 nm. Nevertheless, the addition of MWCNTs was found to be beneficial in enhancing the hardness of alloys containing 0.2 wt%, 0.2 wt% nickel-coated, 0.5 wt%, and 1 wt% MWCNTs by 9%, 24%, 32%, and 15%, respectively, as compared with the unreinforced A345 matrix. It was also found that the 0.5 wt% MWCNT-A356 matrix exhibited an improvement in the creep lifetime by more than two orders of magnitude.
  6. Rhee SY, Blanco JL, Jordan MR, Taylor J, Lemey P, Varghese V, et al.
    PLoS Med, 2015 Apr;12(4):e1001810.
    PMID: 25849352 DOI: 10.1371/journal.pmed.1001810
    BACKGROUND: Regional and subtype-specific mutational patterns of HIV-1 transmitted drug resistance (TDR) are essential for informing first-line antiretroviral (ARV) therapy guidelines and designing diagnostic assays for use in regions where standard genotypic resistance testing is not affordable. We sought to understand the molecular epidemiology of TDR and to identify the HIV-1 drug-resistance mutations responsible for TDR in different regions and virus subtypes.

    METHODS AND FINDINGS: We reviewed all GenBank submissions of HIV-1 reverse transcriptase sequences with or without protease and identified 287 studies published between March 1, 2000, and December 31, 2013, with more than 25 recently or chronically infected ARV-naïve individuals. These studies comprised 50,870 individuals from 111 countries. Each set of study sequences was analyzed for phylogenetic clustering and the presence of 93 surveillance drug-resistance mutations (SDRMs). The median overall TDR prevalence in sub-Saharan Africa (SSA), south/southeast Asia (SSEA), upper-income Asian countries, Latin America/Caribbean, Europe, and North America was 2.8%, 2.9%, 5.6%, 7.6%, 9.4%, and 11.5%, respectively. In SSA, there was a yearly 1.09-fold (95% CI: 1.05-1.14) increase in odds of TDR since national ARV scale-up attributable to an increase in non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance. The odds of NNRTI-associated TDR also increased in Latin America/Caribbean (odds ratio [OR] = 1.16; 95% CI: 1.06-1.25), North America (OR = 1.19; 95% CI: 1.12-1.26), Europe (OR = 1.07; 95% CI: 1.01-1.13), and upper-income Asian countries (OR = 1.33; 95% CI: 1.12-1.55). In SSEA, there was no significant change in the odds of TDR since national ARV scale-up (OR = 0.97; 95% CI: 0.92-1.02). An analysis limited to sequences with mixtures at less than 0.5% of their nucleotide positions—a proxy for recent infection—yielded trends comparable to those obtained using the complete dataset. Four NNRTI SDRMs—K101E, K103N, Y181C, and G190A—accounted for >80% of NNRTI-associated TDR in all regions and subtypes. Sixteen nucleoside reverse transcriptase inhibitor (NRTI) SDRMs accounted for >69% of NRTI-associated TDR in all regions and subtypes. In SSA and SSEA, 89% of NNRTI SDRMs were associated with high-level resistance to nevirapine or efavirenz, whereas only 27% of NRTI SDRMs were associated with high-level resistance to zidovudine, lamivudine, tenofovir, or abacavir. Of 763 viruses with TDR in SSA and SSEA, 725 (95%) were genetically dissimilar; 38 (5%) formed 19 sequence pairs. Inherent limitations of this study are that some cohorts may not represent the broader regional population and that studies were heterogeneous with respect to duration of infection prior to sampling.

    CONCLUSIONS: Most TDR strains in SSA and SSEA arose independently, suggesting that ARV regimens with a high genetic barrier to resistance combined with improved patient adherence may mitigate TDR increases by reducing the generation of new ARV-resistant strains. A small number of NNRTI-resistance mutations were responsible for most cases of high-level resistance, suggesting that inexpensive point-mutation assays to detect these mutations may be useful for pre-therapy screening in regions with high levels of TDR. In the context of a public health approach to ARV therapy, a reliable point-of-care genotypic resistance test could identify which patients should receive standard first-line therapy and which should receive a protease-inhibitor-containing regimen.

  7. Ramesh, S., Shanti, R., Chin, S.F.
    ASM Science Journal, 2011;5(1):19-26.
    MyJurnal
    In this present study, a series of polymer electrolyte thin films were synthesized by incorporating different ratios of lithium triflate (LiCF3SO3) in a low molecular weight polyvinyl chloride (PVC) matrix by the solution casting technique. The incorporation of LiCF3SO3 suppressed the high degree of crystallinity in PVC enabling the system to possess an appreciable ionic conductivity. The ionic conductivity of the samples, with different LiCF3SO3 content, was determined by the aid of ac impedance spectroscopy. The highest ionic conductivity of 4.04  10–9 S cm–1 was identified for the composition of PVC: LiCF3SO3 (75:25). Further understanding of the ionic conductivity mechanism was based on temperature-dependent conductivity data which obeyed Arrhenius theory, indicating that the ionic conductivity enhancement was thermally assisted. The possible dipole-dipole interaction between the chemical constituents was confirmed with changes in cage peak, analysed using Fourier transform infrared spectroscopy.
  8. Ramesh S, Yaghoubi A, Lee KY, Chin KM, Purbolaksono J, Hamdi M, et al.
    J Mech Behav Biomed Mater, 2013 Sep;25:63-9.
    PMID: 23726923 DOI: 10.1016/j.jmbbm.2013.05.008
    Forsterite (Mg2SiO4) because of its exceptionally high fracture toughness which is close to that of cortical bones has been nominated as a possible successor to calcium phosphate bioceramics. Recent in vitro studies also suggest that forsterite possesses good bioactivity and promotes osteoblast proliferation as well as adhesion. However studies on preparation and sinterability of nanocrystalline forsterite remain scarce. In this work, we use a solid-state reaction with magnesium oxide (MgO) and talc (Mg3Si4(OH)2) as the starting precursors to synthesize forsterite. A systematic investigation was carried out to elucidate the effect of preparatory procedures including heat treatment, mixing methods and sintering temperature on development of microstructures as well as the mechanical properties of the sintered forsterite body.
  9. Ramesh S, Ajik S
    Med J Malaysia, 2012 Dec;67(6):629-30.
    PMID: 23770963 MyJurnal
    Scalp defects and lacerations present a reconstructive challenge to plastic surgeons. Many methods have been described from the use of skin grafting to rotation flaps. Here we present a method of closure of a contaminated scalp wound with the use of Kirschner wires. In our case, closure of scalp laceration was made possible with the use of 1.4 Kirschner wires and cable tie/ zip tie fasteners. The duration to closure of wound was 10 days. In reconstructing the scalp defect, this method was found to adhere to principles of scalp reconstruction. There were no post operative complications found from the procedure. On initial application on the edge of the wound, tension applied caused the K wires to cut through the wound edge. On replacement of K wires 1cm away from wound edge the procedure was not plagued by any further complication. In conclusion we find scalp closure with Kirschner wires are a simple and effective method for scalp wound closure.
  10. Ramesh S, Shanti R, Morris E
    Carbohydr Polym, 2013 Jan 2;91(1):14-21.
    PMID: 23044100 DOI: 10.1016/j.carbpol.2012.07.061
    Polymer electrolytes were developed by solution casting technique utilizing the materials of cellulose acetate (CA), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and deep eutectic solvent (DES). The DES is synthesized from the mixture of choline chloride and urea of 1:2 ratios. The increasing DES content well plasticizes the CA:LiTFSI:DES matrix and gradually improves the ionic conductivity and chemical integrity. The highest conducting sample was identified for the composition of CA:LiTFSI:DES (28 wt.%:12 wt.%:60 wt.%), which has the greatest ability to retain the room temperature ionic conductivity over the entire 30 days of storage time. The changes in FTIR cage peaks upon varying the DES content in CA:LiTFSI:DES prove the complexation. This complexation results in the collapse of CA matrix crystallinity, observed from the reduced intensity of XRD diffraction peaks. The DES-plasticized sample is found to be more heat-stable compared to pure CA. Nevertheless, the addition of DES diminishes the CA:LiTFSI matrix's heat-resistivity but at the minimum addition the thermal stability is enhanced.
  11. Ramesh S, Serjius A, Wong TB, Jagjeet S, John R
    Med J Malaysia, 2008 Oct;63(4):343-5.
    PMID: 19385502 MyJurnal
    Penile reconstructive surgeries are performed mainly as radical treatment for conditions associated with congenital abnormalities of the urethra or penis, after penile trauma, penile cancer, short penis, corporal fibrosis and in cases of gender reassignment. We present here a method of penile reconstruction with a pre fabricated radial forearm free flap incorporating the segment of the radius for structural support.
  12. Ramesh S, Tan CY, Aw KL, Yeo WH, Hamdi M, Sopyan I, et al.
    Med J Malaysia, 2008 Jul;63 Suppl A:89-90.
    PMID: 19024998
    The sintering behaviour of a commercial HA and synthesized HA was investigated over the temperature range of 700 degrees C to 1400 degrees C in terms of phase stability, bulk density, Young's modulus and Vickers hardness. In the present research, a wet chemical precipitation reaction was successfully employed to synthesize a submicron, highly crystalline, high purity and single phase stoichiometric HA powder that is highly sinteractive particularly at low temperature regimes below 1100 degrees C. It has been revealed that the sinterability of the synthesized HA was significantly greater than that of the commercial HA. The temperature for the onset of sintering and the temperature required to achieve densities above 98% of theoretical value were approximately 150 degrees C lower for the synthesized HA than the equivalent commercial HA. Nevertheless, decomposition of HA phase upon sintering was not observed in the present work for both powders.
  13. Ramesh S, Yuen TF, Shen CJ
    PMID: 17600757
    Polymer electrolytes based on poly(ethylene oxide)-lithium triflate (PEO-LiCF3SO3) and poly(ethylene oxide)-lithium sulphate (PEO-Li2S4) were prepared by using solution casting method. Measurements of conductivity and dielectric were carried out on these films as a function of frequency at various temperatures. It was observed that PEO-LiCF3SO3 polymer electrolytes have higher conductivity. The interaction between PEO and Li salts were studied by Fourier transform infrared (FTIR).
  14. Ramesh S, Leen KH, Kumutha K, Arof AK
    Spectrochim Acta A Mol Biomol Spectrosc, 2007 Apr;66(4-5):1237-42.
    PMID: 16919998
    The polymer electrolytes composing of the blend of polyvinyl chloride-polymethyl methacrylate (PVC/PMMA) with lithium triflate (LiCF3SO3) as salt, ethylene carbonate (EC) and dibutyl phthalate (DBP) as plasticizers and silica (SiO2) as the composite filler were prepared. FTIR studies confirm the complexation between PVC/PMMA blends. The CCl stretching mode at 834 cm-1 for pure PVC is shifted to 847 cm-1 in PVC-PMMA-LiCF3SO3 system. This suggests that there is interaction between Cl in PVC with Li+ ion from LiCF3SO3. The band due to OCH3 at 1150 cm-1 for PVC-PMMA blend is shifted to 1168 cm-1 in PVC-PMMA-LiCF3SO3 system. This shift is expected to be due to the interaction between Li+ ion and the oxygen atom in PMMA. The symmetric vibration band and the asymmetric vibration band of LiCF3SO3 at 1033 and 1256 cm-1 shifted to 1075 and 1286 cm-1 in the DBP-EC plasticized PVC-PMMA-LiCF3SO3 complexes. The interaction between Li+ ions and SiO2 will lead to an increase in the number of free plasticizers (which does not interact with Li+ ions). When the silica content increases from 2% to 5%, the intensity of the peak at 896 cm-1 (due to the ring breathing vibration of free EC) increases in PVC-PMMA-LiCF3SO3-DBP-EC system.
  15. Ramesh S, Shanti R, Morris E
    Carbohydr Polym, 2012 Jan 04;87(1):701-706.
    PMID: 34663024 DOI: 10.1016/j.carbpol.2011.08.047
    A series of polymer electrolytes composed of corn starch (CS), lithium bis(trifluoromethanesulfonyl)imide (LITFSI) and deep eutectic solvent (DES) were fabricated by solution casting technique. The DES was synthesized from a mixture of choline chloride and urea at a molar ratio of 1:2. The addition of DES is crucial in enhancing the room temperature ionic conductivity by increasing the amorphous elastomeric phase in CS:LITFSI matrix. The ionic transport mechanism is improved and appreciable amount of ion conducting polymer electrolytes is produced. The highest ionic conductivity achieved for the polymer electrolyte composition CS:LiTFSI:DES (14wt.%:6wt.%:80wt.%) is 1.04×10-3Scm-1. The anomalies that were observed with the addition of DES upon formation of neutral ion multiples were visually revealed by the SEM micrographs. The possible dipole-dipole interaction between the constituents was visualized by the FTIR spectroscopy upon change in cage peaks.
  16. Rajhans V, Mohammed CA, Ve RS, Prabhu A
    Educ Health (Abingdon), 2021 7 3;34(1):22-28.
    PMID: 34213440 DOI: 10.4103/efh.EfH_69_20
    Background: Current trends in health professions education are aligned to meet the needs of the millennial learner. The aim of this study was to identify learners' perceptions of an ongoing journal club (JC) activity in the optometry curriculum and evaluate the utility and efficiency of this method in promoting student learning.

    Methods: A qualitative approach with a phenomenological research design was adopted. The perceptions of undergraduate and postgraduate optometry students about JCs were captured using focus group discussions. A narrative thematic analysis was done using the verbatim transcripts and moderator's notes. Results are reported using "consolidated criteria for reporting qualitative research" guidelines.

    Results: A total of 33 optometry students participated in the study. Data analysis revealed three major themes related to (i) The ongoing practice of JC, (ii) student perceptions of JC and its relevance in facilitating student learning, and (iii) suggestions for modification of JC for achieving optimal educational outcomes.

    Discussion: Student feedback indicates that an instructional redesigning of JC is necessary, considering the characteristics and expectations of the current generation of learners and the rapid strides made in the field of educational technology. The recommendations provided are likely to resurrect an age-old approach that still has educational relevance if blended with collaborative learning formats and appropriate technology.

  17. Prabhu AV, Ve RS, Talukdar J, Chandrasekaran V
    Oman J Ophthalmol, 2019 10 11;12(3):145-149.
    PMID: 31902987 DOI: 10.4103/ojo.OJO_190_2018
    AIM: The aim of this study is to estimate the prevalence of visual impairment among school-going children in Udupi district, Karnataka.

    MATERIALS AND METHODS: A cross-sectional study across eleven schools from both urban and rural parts of Udupi taluk was conducted to report the magnitude of visual impairment among the schoolchildren. Complex survey design was used in allocating the sample size through stratification and clustering. Totally 1784 schoolchildren between the age groups of 5 and 15 years participated in the study. Presenting visual acuity and objective refraction was measured using computerized logMAR acuity charts and Plusoptix A09 photorefractor, respectively. Manifest ocular deviation or squint was also recorded.

    RESULTS: The mean age of the students was found to be 10.62 ± 2.72 years. The prevalence of visual impairment, i.e., visual acuity worse than or equal to 20/40 in the better eye was found to be 4.32% (95% confidence interval: 3.38%, 5.26%). The prevalence rate was significantly higher among students from urban area (5.6%) compared to those from rural area (3.6%) (P = 0.011).

    CONCLUSION: Visual impairment was found to be 4.32% in the school-going population of Udupi district. Effective and user-friendly devices aided the visual deficit screening including refractive error and squint.

  18. Pal B, Yang S, Ramesh S, Thangadurai V, Jose R
    Nanoscale Adv, 2019 Oct 09;1(10):3807-3835.
    PMID: 36132093 DOI: 10.1039/c9na00374f
    Electrolytes are one of the vital constituents of electrochemical energy storage devices and their physical and chemical properties play an important role in these devices' performance, including capacity, power density, rate performance, cyclability and safety. This article reviews the current state of understanding of the electrode-electrolyte interaction in supercapacitors and battery-supercapacitor hybrid devices. The article discusses factors that affect the overall performance of the devices such as the ionic conductivity, mobility, diffusion coefficient, radius of bare and hydrated spheres, ion solvation, viscosity, dielectric constant, electrochemical stability, thermal stability and dispersion interaction. The requirements needed to design better electrolytes and the challenges that still need to be addressed for building better supercapacitive devices for the competitive energy storage market have also been highlighted.
  19. Pai YS, Yap HJ, Md Dawal SZ, Ramesh S, Phoon SY
    Sci Rep, 2016 06 07;6:27380.
    PMID: 27271840 DOI: 10.1038/srep27380
    This study presents a modular-based implementation of augmented reality to provide an immersive experience in learning or teaching the planning phase, control system, and machining parameters of a fully automated work cell. The architecture of the system consists of three code modules that can operate independently or combined to create a complete system that is able to guide engineers from the layout planning phase to the prototyping of the final product. The layout planning module determines the best possible arrangement in a layout for the placement of various machines, in this case a conveyor belt for transportation, a robot arm for pick-and-place operations, and a computer numerical control milling machine to generate the final prototype. The robotic arm module simulates the pick-and-place operation offline from the conveyor belt to a computer numerical control (CNC) machine utilising collision detection and inverse kinematics. Finally, the CNC module performs virtual machining based on the Uniform Space Decomposition method and axis aligned bounding box collision detection. The conducted case study revealed that given the situation, a semi-circle shaped arrangement is desirable, whereas the pick-and-place system and the final generated G-code produced the highest deviation of 3.83 mm and 5.8 mm respectively.
  20. Omar FS, Duraisamy N, Ramesh K, Ramesh S
    Biosens Bioelectron, 2016 May 15;79:763-75.
    PMID: 26774092 DOI: 10.1016/j.bios.2016.01.013
    Nicotinamide Adenine Dinucleotide (NADH) is an important coenzyme in the human body that participates in many metabolic reactions. The impact of abnormal concentrations of NADH significantly causes different diseases in human body. Electrochemical detection of NADH using bare electrode is a challenging task especially in the presence of main electroactive interferences such as ascorbic acid (AA), uric acid (UA) and dopamine (DA). Modified electrodes have been widely explored to overcome the problems of poor sensitivity and selectivity occurred from bare electrodes. This review gives an overview on the progress of using conducting polymers, polyelectrolyte and its composites (co-polymer, carbonaceous, metal, metal oxide and clay) based modified electrodes for the sensing of NADH. In addition, developments on the fabrication of numerous conducting polymer composites based modified electrodes are clearly described.
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