Displaying publications 1 - 20 of 27 in total

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  1. What is the ultimate goal in acid-base regulation?
    Balakrishnan S, Gopalakrishnan M, Alagesan M, Prakash ES
    Adv Physiol Educ, 2007 Mar;31(1):51-4.
    PMID: 17327583
    It is common to see chapters on acid-base physiology state that the goal of acid-base regulatory mechanisms is to maintain the pH of arterial plasma and not arterial Pco(2) (Pa(CO(2))) or plasma HCO(3). A hypothetical situation in which the Pa(CO(2)) of arterial plasma is 80 mmHg and the plasma HCO(3) concentration is 48 mM is presented and analyzed to get over this misconception. As per the modified Henderson equation, the pH of arterial plasma would be 7.4; however, we explain that this may be associated with intracellular acidosis due to intracellular hypercapnia and that derangement of homeostasis is evident from the occurrence of respiratory depression and, eventually, coma in the patient described. This suggests that the ultimate goal of acid-base regulatory mechanisms is not just the maintenance of the pH of arterial plasma but the maintenance of the steady-state pH of intracellular fluid as well.
  2. Fulltext Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film
    Perumal V, Hashim U, Gopinath SC, Haarindraprasad R, Liu WW, Poopalan P, et al.
    PLoS One, 2015;10(12):e0144964.
    PMID: 26694656 DOI: 10.1371/journal.pone.0144964
    The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Aux (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5-10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications.
  3. The usage of Gellhorn pessary in pelvic organ prolapse and in regards to success, continuity of use and effect on symptoms: a retrospective study of 2 years
    Ramanujam S, Balakrishnan S
    Med J Malaysia, 2023 Nov;78(6):705-710.
    PMID: 38031210
    INTRODUCTION: Pelvic organ prolapse (POP) is a condition involving weakened pelvic floor muscles causing organs to protrude. Conservative POP treatment comprises pelvic floor exercises and vaginal pessaries. Besides conservative care, surgery is offered. However, surgery is invasive, risky and unsuitable for those with serious medical conditions. This study aims to assess the acceptance, success and outcomes of the Gellhorn pessary for POP treatment, especially in advanced cases.

    MATERIALS AND METHODS: The present study is a retrospective cohort study using hospital medical records (patient files) from October 2019 to November 2021 (for 2 years). This study was performed in Malaysian women (n=53) suffering from advanced stages of POP, in which Gellhorn pessaries of diameter (44-76mm) were inserted by trained personnel. Pelvic Floor Distress Inventory-20 (PFDI-20) and Pelvic Floor Impact Questionnaire-7 (PFIQ-7) were used to measure patients' symptoms and quality of life before and after Gellhorn pessary fitting. Patients were reassessed every three months for two years and their satisfaction scores were recorded.

    RESULTS: We observed a significant difference in pre-test (pre-fitting) and post-test (three months post-fitting) scores on all three subscales and the PFIQ-7 total score. Twentyeight (52.83%) patients continued the use of Gellhorn pessary for at least 24 months, whereas 25 (47.20%) patients discontinued during this period. A retrospective analysis of the patients who discontinued Gellhorn pessary showed that 13 (24.52%) patients gave up the use of pessary for definitive surgery. It is noteworthy to mention here that only one out of the 13 patients who were awaiting surgery, chose surgery and the remaining 12 changed their mind after being fitted with the Gellhorn pessary. Seven (13.20%) patients declined reinsertion due to discomfort and voiding difficulties and refused further intervention, whereas three (5.66%) patients requested a ring pessary. Two (3.77%) patients, requested the removal of pessary due to vesicovaginal fistula and rectovaginal fistula (caused by an impacted pessary). The rate of continued use was 79.24% (42 patients) after 1st year and 52.83% (28 patients) at the end of two years.

    CONCLUSION: In the current study, the Gellhorn pessary was used to treat stage 3 and 4 POP with significant symptom reduction post-fitting. More than half of the patients continued to use the pessary after 24 months of fitting. Therefore, the Gellhorn pessary can be used as a treatment strategy for stage 3 and 4 POP with reasonable acceptance in the Malaysian population.

  4. Rupture of the pregnant uterus--a 21-year review
    Rachagan SP, Raman S, Balasundram G, Balakrishnan S
    Aust N Z J Obstet Gynaecol, 1991 Feb;31(1):37-40.
    PMID: 1872771
    Uterine rupture is still a common problem in developing countries although even here the incidence varies from urban to rural settings. This article is a review of uterine rupture in an urban referral hospital in Malaysia. It examines aetiology, clinical presentation, complications and management of the problem. Meticulous screening of patients together with optimal antenatal and intrapartum care will markedly reduce the incidence of uterine rupture. Early diagnosis and prompt treatment will further help reduce morbidity and mortality to both mother and fetus.
  5. Reye and Reye-like syndromes: results of a pilot study in Peninsular Malaya, 1986
    Sinniah D, Sinniah R, Yap YF, Singh M, George R, Lim NL, et al.
    Acta Paediatr Jpn, 1990 Aug;32(4):385-90.
    PMID: 2288220
    A pilot epidemiologic study of all cases of Reye and Reye-like syndromes was undertaken at 8 representative major hospitals in Peninsular Malaya from January 1st to December 31st 1986. The cases were classified as definitive Reye's syndrome, clinical Reye's syndrome and encephalo-hepatopathies. Less than 50% of cases reviewed fulfilled the National Center for Disease Control criteria for clinical Reye's syndrome. Causes of Reye-like syndromes/encephalo-hepatopathies included fulminant hepatitis, Japanese B encephalitis, dengue, septicaemia, and complex febrile fits. It was not possible to differentiate clinical Reye's syndrome from the other encephalo-hepatopathies by either the clinical features (except for jaundice) or biochemical parameters. Liver biopsy is necessary for a definitive diagnosis of Reye's syndrome in Malaysia, because of the high prevalence of Reye-like diseases. The mortality rate in the 2 groups of patients is similar. Ingestion of salicylates was not found to be significantly associated with Reye and Reye-like syndromes in this study.
  6. Red cell enzymes in cord blood and plasma bilirubin levels in the first week of life
    Lie-Injo LE, Ng T, Balakrishnan S
    Clin Chim Acta, 1974 Jan 19;50(1):77-83.
    PMID: 4856203 DOI: 10.1016/0009-8981(74)90079-5
  7. Fulltext Plesiomonas shigelloides associated with diarrhoeal disease in Malaysian children
    Lim YS, Young LJ, Balakrishnan S
    Singapore Med J, 1987 Dec;28(6):534-6.
    PMID: 3441796
    Plesiomonas shigelloides was isolated from 5 (2.1%) of the 234 children with diarrhoea and none of the 230 controls. In one child, the organism was found in association with Salmonella. Two strains had Shigella sonnei phase I antigen. All the strains were susceptible to the aminoglycosides, cephalosporins, nalidixic acid, nitrofurantoin, chloramphenicol and cotrimoxazole; but resistant to the penicillins. Alkaline peptone water enrichment subcultured to desoxycholale citrate agar proved to be a useful method for isolating this organism from faeces. As the roie of P. shigelloides in causing gastrointestinal disease remains controversial, further studies are necessary to determine its enteropathogenicily.
  8. Molecular dynamics simulation and structural analysis of aquaporin Z from an Antarctic Pseudomonas sp. strain AMS3
    Balakrishnan S, Rahman RNZRA, Noor NDM, Latip W, Ali MSM
    J Biomol Struct Dyn, 2023;41(21):11498-11509.
    PMID: 36598349 DOI: 10.1080/07391102.2022.2164519
    Aquaporin is a water channel protein that facilitates the movement of water across the cell membrane. Aquaporin from the Antarctic region has been noted for its psychrophilic properties and its ability to perform at a lower temperature but there remains limited understanding of the water mechanism of Antarctic Pseudomonas sp. strain AMS3 However, studies regarding aquaporin isolated from psychrophilic Pseudomonas sp. are still scattered. Recently, the genome sequence of an Antarctic Pseudomonas sp. strain AMS3 revealed a gene sequence encoding for a putative aquaporin designated as AqpZ1 AMS3. In this study, structure analysis and a molecular dynamics (MD) simulation of a predicted model of a fully hydrated aquaporin tetramer embedded in a lipid bilayer was performed at different temperatures for structural flexibility and stability analysis. The MD simulation results revealed that the structures were able to remain stable at low to medium temperatures. The protein was observed to have high flexibility in the loop region as compared to the helices region throughout the simulated temperatures. The selectivity filter and NPA motifs play a major role in solute selectivity and the pore radius of the protein. The structural and functional characterization of this psychrophilic aquaporin provides new insights for the future applications of this protein.Communicated by Ramaswamy H. Sarma.
  9. Fulltext Low Temperature Annealed Zinc Oxide Nanostructured Thin Film-Based Transducers: Characterization for Sensing Applications
    Haarindraprasad R, Hashim U, Gopinath SC, Kashif M, Veeradasan P, Balakrishnan SR, et al.
    PLoS One, 2015;10(7):e0132755.
    PMID: 26167853 DOI: 10.1371/journal.pone.0132755
    The performance of sensing surfaces highly relies on nanostructures to enhance their sensitivity and specificity. Herein, nanostructured zinc oxide (ZnO) thin films of various thicknesses were coated on glass and p-type silicon substrates using a sol-gel spin-coating technique. The deposited films were characterized for morphological, structural, and optoelectronic properties by high-resolution measurements. X-ray diffraction analyses revealed that the deposited films have a c-axis orientation and display peaks that refer to ZnO, which exhibits a hexagonal structure with a preferable plane orientation (002). The thicknesses of ZnO thin films prepared using 1, 3, 5, and 7 cycles were measured to be 40, 60, 100, and 200 nm, respectively. The increment in grain size of the thin film from 21 to 52 nm was noticed, when its thickness was increased from 40 to 200 nm, whereas the band gap value decreased from 3.282 to 3.268 eV. Band gap value of ZnO thin film with thickness of 200 nm at pH ranging from 2 to 10 reduces from 3.263eV to 3.200 eV. Furthermore, to evaluate the transducing capacity of the ZnO nanostructure, the refractive index, optoelectric constant, and bulk modulus were analyzed and correlated. The highest thickness (200 nm) of ZnO film, embedded with an interdigitated electrode that behaves as a pH-sensing electrode, could sense pH variations in the range of 2-10. It showed a highly sensitive response of 444 μAmM-1cm-2 with a linear regression of R2 =0.9304. The measured sensitivity of the developed device for pH per unit is 3.72μA/pH.
  10. Iron incorporated heterogeneous catalyst from rice husk ash
    Adam F, Kandasamy K, Balakrishnan S
    J Colloid Interface Sci, 2006 Dec 1;304(1):137-43.
    PMID: 16996077
    Silica supported iron catalyst was prepared from rice husk ash (RHA) via the sol-gel technique using an aqueous solution of iron(III) salt in 3.0 M HNO3. The sample was dried at 110 degrees C and labeled as RHA-Fe. A sample of RHA-Fe was calcined at 700 degrees C for 5 h and labeled as RHA-Fe700. X-ray diffraction spectrogram showed that both RHA-Fe and RHA-Fe700 were amorphous. The SEM/EDX results showed that the metal was present as agglomerates and the Fe ions were not homogeneously distributed in RHA-Fe but RHA-Fe700 was shown to be homogeneous. The specific surface areas for RHA-Fe and RHA-Fe700 were determined by BET nitrogen adsorption studies and found to be 87.4 and 55.8 m(2) g(-1), respectively. Both catalysts showed high activity in the reaction between toluene and benzyl chloride. The mono-substituted benzyltoluene was the major product and both catalysts yielded more than 92% of the product. The GC showed that both the ortho- and para-substituted monoisomers were present in about equal quantities. The minor products consisting of 16 di-substituted isomers were also observed in the GC-MS spectra of both catalytic products. The catalyst was found to be reusable without loss of activity and with no leaching of the metal.
  11. Fulltext Hyperbilirubinaemia and erythrocytic glucose 6 phosphate dehydrogenase deficiency in Malaysian children
    Hon AT, Balakrishnan S, Ahmad Z
    Med J Malaysia, 1989 Mar;44(1):30-4.
    PMID: 2626111
    Cord blood from 8,975 babies delivered in Hospital Sultanah Aminah Johor Bahru over a period of eight months (1st August 1985 to 31st March 1986) were screened for G6PD deficiency. The overall incidence was 4.5% in Chinese, 3.5% in Malays and 1.5% in Indian babies. One hundred of these babies were observed in the nursery for seven days and their daily serum bilirubin recorded. The serum bilirubin peaked at 96 hours to a value of 12mg%. None of the babies in the nursery developed a serum bilirubin level of more than 15mg%. Six of the babies with G6PD deficiency that were sent home were readmitted with hyperbilirubinaemia that needed exchange transfusion.
  12. Fulltext Gram-negative infection as an unusual cause of endocarditis in a hemodialysis patient
    Balakrishnan S, Aamar A, Rhee S, Zakaria S, Khaliq W
    Med J Malaysia, 2016 Jun;71(3):152-3.
    PMID: 27495894
    Gram-negative endocarditis is rare and it has high mortality if there is a delay in diagnosis and treatment. Gram-negative organisms should be considered in the differential diagnosis of IE in hemodialysis patients. Central lineassociated bloodstream infections (CLABSIs) can be prevented by following sterile measures during catheter insertion and proper management of catheter site.
  13. Gold-nanorod enhances dielectric voltammetry detection of c-reactive protein: A predictive strategy for cardiac failure
    Letchumanan I, Md Arshad MK, Balakrishnan SR, Gopinath SCB
    Biosens Bioelectron, 2019 Apr 01;130:40-47.
    PMID: 30716591 DOI: 10.1016/j.bios.2019.01.042
    This paper primarily demonstrates the approach to enhance the sensing performance on antigen C-reactive protein (CRP) and anti-CRP antibody binding event. A nanogapped electrode structure with the gap of ~100 nm was modified by the anti-CRP antibody (Probe) to capture the available CRP. In order to increase the amount of antigen to be captured, a gold nanorod with 119 nm in length and 25 nm in width was integrated, to increase the surface area. A comparative study between the existence and non-existence of gold nanorod utilization was evaluated. Analysis of the sensing surface was well-supported by atomic force microscopy, scanning electron microscopy, 3D nano-profilometry, high-power microscopy and UV-Vis spectroscopy. The dielectric voltammetric analysis was carried out from 0 V to 2 V. The sensitivity was calculated based on 3σ and attained as low as 1 pM, which is tremendously low compared to real CRP concentration (119 nM) in human blood serum. The gold nanorod conjugation with antibody has enhanced the sensitivity to 100 folds (10 fM). The specificity of the CRP detection by the proposed strategy was anchored by ELISA and failure in the detection of human blood clotting factor IX by voltammetry. Despite, CRP antigen was further detected in human serum by spiking CRP to run-through the detection with the physiologically relevant samples.
  14. Fulltext Global, Regional, and National Cancer Incidence, Mortality, Years of Life Lost, Years Lived With Disability, and Disability-Adjusted Life-Years for 29 Cancer Groups, 1990 to 2017: A Systematic Analysis for the Global Burden of Disease Study
    Global Burden of Disease Cancer Collaboration, Fitzmaurice C, Abate D, Abbasi N, Abbastabar H, Abd-Allah F, et al.
    JAMA Oncol, 2019 Dec 01;5(12):1749-1768.
    PMID: 31560378 DOI: 10.1001/jamaoncol.2019.2996
    IMPORTANCE: Cancer and other noncommunicable diseases (NCDs) are now widely recognized as a threat to global development. The latest United Nations high-level meeting on NCDs reaffirmed this observation and also highlighted the slow progress in meeting the 2011 Political Declaration on the Prevention and Control of Noncommunicable Diseases and the third Sustainable Development Goal. Lack of situational analyses, priority setting, and budgeting have been identified as major obstacles in achieving these goals. All of these have in common that they require information on the local cancer epidemiology. The Global Burden of Disease (GBD) study is uniquely poised to provide these crucial data.

    OBJECTIVE: To describe cancer burden for 29 cancer groups in 195 countries from 1990 through 2017 to provide data needed for cancer control planning.

    EVIDENCE REVIEW: We used the GBD study estimation methods to describe cancer incidence, mortality, years lived with disability, years of life lost, and disability-adjusted life-years (DALYs). Results are presented at the national level as well as by Socio-demographic Index (SDI), a composite indicator of income, educational attainment, and total fertility rate. We also analyzed the influence of the epidemiological vs the demographic transition on cancer incidence.

    FINDINGS: In 2017, there were 24.5 million incident cancer cases worldwide (16.8 million without nonmelanoma skin cancer [NMSC]) and 9.6 million cancer deaths. The majority of cancer DALYs came from years of life lost (97%), and only 3% came from years lived with disability. The odds of developing cancer were the lowest in the low SDI quintile (1 in 7) and the highest in the high SDI quintile (1 in 2) for both sexes. In 2017, the most common incident cancers in men were NMSC (4.3 million incident cases); tracheal, bronchus, and lung (TBL) cancer (1.5 million incident cases); and prostate cancer (1.3 million incident cases). The most common causes of cancer deaths and DALYs for men were TBL cancer (1.3 million deaths and 28.4 million DALYs), liver cancer (572 000 deaths and 15.2 million DALYs), and stomach cancer (542 000 deaths and 12.2 million DALYs). For women in 2017, the most common incident cancers were NMSC (3.3 million incident cases), breast cancer (1.9 million incident cases), and colorectal cancer (819 000 incident cases). The leading causes of cancer deaths and DALYs for women were breast cancer (601 000 deaths and 17.4 million DALYs), TBL cancer (596 000 deaths and 12.6 million DALYs), and colorectal cancer (414 000 deaths and 8.3 million DALYs).

    CONCLUSIONS AND RELEVANCE: The national epidemiological profiles of cancer burden in the GBD study show large heterogeneities, which are a reflection of different exposures to risk factors, economic settings, lifestyles, and access to care and screening. The GBD study can be used by policy makers and other stakeholders to develop and improve national and local cancer control in order to achieve the global targets and improve equity in cancer care.

  15. Fabrication of interdigitated high-performance zinc oxide nanowire modified electrodes for glucose sensing
    Haarindraprasad R, Hashim U, Gopinath SC, Perumal V, Liu WW, Balakrishnan SR
    Anal Chim Acta, 2016 Jun 21;925:70-81.
    PMID: 27188319 DOI: 10.1016/j.aca.2016.04.030
    Diabetes is a metabolic disease with a prolonged elevated level of glucose in the blood leads to long-term complications and increases the chances for cardiovascular diseases. The present study describes the fabrication of a ZnO nanowire (NW)-modified interdigitated electrode (IDE) to monitor the level of blood glucose. A silver IDE was generated by wet etching-assisted conventional lithography, with a gap between adjacent electrodes of 98.80 μm. The ZnO-based thin films and NWs were amended by sol-gel and hydrothermal routes. High-quality crystalline and c-axis orientated ZnO thin films were observed by XRD analyses. The ZnO thin film was annealed for 1, 3 and 5 h, yielding a good-quality crystallite with sizes of 50, 100 and 110 nm, and the band gaps were measured as 3.26, 3.20 and 3.17 eV, respectively. Furthermore, a flower-modeled NW was obtained with the lowest diameter of 21 nm. Our designed ZnO NW-modified IDE was shown to have a detection limit as low as 0.03 mg/dL (correlation coefficient = 0.98952) of glucose with a low response time of 3 s, perform better than commercial glucose meter, suitable to instantly monitor the glucose level of diabetes patients. This study demonstrated the high performance of NW-mediated IDEs for glucose sensing as alternative to current glucose sensors.
  16. Effect of Paclitaxel-Loaded PLGA Nanoparticles on MDA-MB Type Cell Lines: Apoptosis and Cytotoxicity Studies
    Vijayan V, Shalini K, Yugesvaran V, Yee TH, Balakrishnan S, Palanimuthu VR
    Curr Pharm Des, 2018;24(28):3366-3375.
    PMID: 30179118 DOI: 10.2174/1381612824666180903110301
    BACKGROUND: Triple-Negative Breast Cancer is an aggressive type of breast cancer, which is not treatable by chemotherapy drugs, due to the lack of Estrogen Receptor (ER), Progesterone Receptor (PR) expression and Human Epidermal Growth Factor Receptor 2 (HER2) on the cell surface.

    OBJECTIVE: The aim of this study was to compare the effect of paclitaxel loaded PLGA nanoparticle (PTX-NPs) on the cytotoxicity and apoptosis of the different MDA-MB type of cell lines.

    METHOD: PTX-NPs were prepared by nanoprecipitation method and characterized earlier. The cytotoxicity of PTX-NPs was evaluated by MTT and LDH assay, later apoptosis was calculated by flow cytometry analysis.

    RESULTS: The prepared NP size of 317.5 nm and zetapontial of -12.7 mV showed drug release of 89.1 % at 48 h. MDA-MB-231 type cell showed significant cytotoxicity by MTT method of 47.4 ± 1.2 % at 24 h, 34.6 ± 0.8 % at 48 h and 23.5 ± 0.5 % at 72 h and LDH method of 35.9 ± 1.5 % at 24 h, 25.4 ± 0.6 % at 48 h and 19.8 ± 2.2 % at 72 h with apoptosis of 47.3 ± 0.4 %.

    CONCLUSION: We have found that PTX-NPs showed the cytotoxic effect on all the MDA-MB cancer cell lines and showed potent anticancer activities against MDA-MB-231 cell line via induction of apoptosis.

  17. Dissemination of Trimethoprim-Sulfamethoxazole Drug Resistance Genes Associated with Class 1 and Class 2 Integrons Among Gram-Negative Bacteria from HIV Patients in South India
    Ramesh Kumar MR, Arunagirinathan N, Srivani S, Dhanasezhian A, Vijaykanth N, Manikandan N, et al.
    Microb Drug Resist, 2017 Jul;23(5):602-608.
    PMID: 27854149 DOI: 10.1089/mdr.2016.0034
    The antibiotic, trimethoprim-sulfamethoxazole (TMP-SMX), is generally used for prophylaxis in HIV individuals to protect them from Pneumocystis jiroveci infection. Long-term use of TMP-SMX develops drug resistance among bacteria in HIV patients. The study was aimed to detect the TMP-SMX resistance genes among gram-negative bacteria from HIV patients. TMP-SMX-resistant isolates were detected by the Kirby-Bauer disc diffusion method. While TMP resistance genes such as dfrA1, dfrA5, dfrA7, and dfrA17 and SMX resistance genes such as sul1 and sul2 were detected by multiplex PCR, class 1 and class 2 integrons were detected by standard monoplex PCR. Of the 151 TMP-SMX-resistant bacterial isolates, 3 were positive for sul1 alone, 48 for sul2 alone, 11 for dfrA7 alone, 21 for sul1 and sul2, 1 for sul1 and dfrA7, 23 for sul2 and dfrA7, 2 for sul2 and dfrA5, 41 for sul1, sul2, and dfrA7, and 1 for sul2, dfrA5, and dfrA7. Of 60 TMP-SMX-resistant isolates positive for integrons, 44 had class 1 and 16 had class 2 integrons. It was found that the prevalence of sul genes (n = 202; p 
  18. Fulltext Comparative Analysis on Dielectric Gold and Aluminium Triangular Junctions: Impact of Ionic Strength and Background Electrolyte by pH Variations
    Letchumanan I, Md Arshad MK, Gopinath SCB, Rajapaksha RDAA, Balakrishnan SR
    Sci Rep, 2020 Apr 22;10(1):6783.
    PMID: 32321969 DOI: 10.1038/s41598-020-63831-w
    Field of generating a surface thin film is emerging broadly in sensing applications to obtain the quick and fast results by forming the high-performance sensors. Incorporation of thin film technologies in sensor development for the better sensing could be a promising way to attain the current requirements. This work predominantly delineates the fabrication of the dielectric sensor using two different sensing materials (Gold and Aluminium). Conventional photolithography was carried out using silicon as a base material and the photo mask of the dielectric sensor was designed by AutoCAD software. The physical characterization of the fabricated sensor was done by Scanning Electron Microscope, Atomic Force Microscope, High Power Microscope and 3D-nano profiler. The electrical characterization was performed using Keithley 6487 picoammeter with a linear sweep voltage of 0 to 2 V at 0.01 V step voltage. By pH scouting, I-V measurements on the bare sensor were carried out, whereby the gold electrodes conducts a least current than aluminium dielectrodes. Comparative analysis with pH scouting reveals that gold electrode is suitable under varied ionic strengths and background electrolytes, whereas aluminium electrodes were affected by the extreme acid (pH 1) and alkali (pH 12) solutions.
  19. Fulltext Chemical, Nutrient and Physicochemical Properties of Brown Seaweed, Sargassum polycystum C. Agardh (Phaeophyceae) Collected from Port Dickson, Peninsular Malaysia
    Nazarudin MF, Alias NH, Balakrishnan S, Wan Hasnan WNI, Noor Mazli NAI, Ahmad MI, et al.
    Molecules, 2021 Aug 27;26(17).
    PMID: 34500650 DOI: 10.3390/molecules26175216
    Recent increased interest in seaweed is motivated by attention generated in their bioactive components that have potential applications in the functional food and nutraceutical industries. In the present study, nutritional composition, metabolite profiles, phytochemical screening and physicochemical properties of freeze-dried brown seaweed, Sargassum polycystum were evaluated. Results showed that the S. polycystum had protein content of 8.65 ± 1.06%, lipid of 3.42 ± 0.01%, carbohydrate of 36.55 ± 1.09% and total dietary fibre content of 2.75 ± 0.58% on dry weight basis. The mineral content of S. polycystum including Na, K, Ca, Mg Fe, Se and Mn were 8876.45 ± 0.47, 1711.05 ± 0.07, 1079.75 ± 0.30, 213.85 ± 0.02, 277.6 ± 0.12, 4.70 ± 0.00 and 4.45 ± 0.00 mg 100/g DW, respectively. Total carotenoid, chlorophyll a and b content in S. polycystum were detected at 45.28 ± 1.77, 141.98 ± 1.18 and 111.29 µg/g respectively. The total amino acid content was 74.90 ± 1.45%. The study revealed various secondary metabolites and major constituents of S. polycystum fibre to include fucose, mannose, galactose, xylose and rhamnose. The metabolites extracted from the seaweeds comprised n-hexadecanoic acid, 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester, benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy- methyl ester, 1-dodecanol, 3,7,11-trimethyl-, which were the most abundant. The physicochemical properties of S. polycystum such as water-holding and swelling capacity were comparable to several commercial fibre-rich products. In conclusion, results of this study indicate that S. polycystum is a potential candidate as functional food sources for human consumption and its cultivation needs to be encouraged.
  20. Fulltext Characterization of Gold-Sputtered Zinc Oxide Nanorods-a Potential Hybrid Material
    Perumal V, Hashim U, Gopinath SC, Rajintra Prasad H, Wei-Wen L, Balakrishnan SR, et al.
    Nanoscale Res Lett, 2016 Dec;11(1):31.
    PMID: 26787050 DOI: 10.1186/s11671-016-1245-8
    Generation of hybrid nanostructures has been attested as a promising approach to develop high-performance sensing substrates. Herein, hybrid zinc oxide (ZnO) nanorod dopants with different gold (Au) thicknesses were grown on silicon wafer and studied for their impact on physical, optical and electrical characteristics. Structural patterns displayed that ZnO crystal lattice is in preferred c-axis orientation and proved the higher purities. Observations under field emission scanning electron microscopy revealed the coverage of ZnO nanorods by Au-spots having diameters in the average ranges of 5-10 nm, as determined under transmission electron microscopy. Impedance spectroscopic analysis of Au-sputtered ZnO nanorods was carried out in the frequency range of 1 to 100 MHz with applied AC amplitude of 1 V RMS. The obtained results showed significant changes in the electrical properties (conductance and dielectric constant) with nanostructures. A clear demonstration with 30-nm thickness of Au-sputtering was apparent to be ideal for downstream applications, due to the lowest variation in resistance value of grain boundary, which has dynamic and superior characteristics.
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