Displaying publications 321 - 340 of 624 in total

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  1. Salina Shaharun, Maizatul S. Shaharun, Mohamad F.M. Shah, Nurul A. Amer
    Sains Malaysiana, 2018;47:207-214.
    Catalytic hydrogenation of carbon dioxide (CO2) to methanol is an attractive way to recycle and utilize CO2. A series of Cu/ZnO/Al2O3/ZrO2 catalysts (CZAZ) containing different molar ratios of Cu/Zn were prepared by the co-precipitation method. The catalysts were characterized by temperature-programmed reduction (TPR), field emission scanning electron microscopy-energy dispersive x-ray analysis (FESEM-EDX) and X-ray diffraction (XRD). Higher surface area, SABET values (42.6-59.9 m2/g) were recorded at low (1) and high (5) Cu/Zn ratios with the minimum value of 35.71 m2/g was found for a Cu/Zn of 3. The reducibility of the metal oxides formed after calcination of catalyst samples was also affected due to change in metal-support interaction. At a reaction temperature of 443 K, total gas pressure of 3.0 MPa and 0.1 g/mL of the CZAZ catalyst, the selectivity to methanol decreased as the Cu/Zn molar ratio increased, and the maximum selectivity of 93.9 was achieved at Cu/Zn molar ratio of 0.33. With a reaction time of 3h, the best performing catalyst was CZAZ75 with Cu/Zn molar ratio of 5 giving methanol yield of 6.4%.
    Matched MeSH terms: Zinc; Zinc Oxide
  2. Sahudin MA, Su'ait MS, Tan LL, Lee YH, Abd Karim NH
    Anal Bioanal Chem, 2019 Sep;411(24):6449-6461.
    PMID: 31392436 DOI: 10.1007/s00216-019-02025-4
    Biogenic amines have attracted interest among researchers because of their importance as biomarkers in determining the quality of food freshness in the food industry. A rapid and simple technique that is able to detect biogenic amines is needed. In this work, a new optical sensing material for one of the biogenic amines, histamine, based on a new zinc(II) salphen complex was developed. The binding of zinc(II) complexes without an electron-withdrawing group (complex 1) and with electron-withdrawing groups (F, complex 2; Cl, complex 3) to histamine resulted in enhancement of fluorescence. All complexes exhibited high affinity for histamine [binding constant of (7.14 ± 0.80) × 104, (3.33 ± 0.03) × 105, and (2.35 ± 0.14) × 105 M-1, respectively]. Complex 2 was chosen as the sensing material for further development of an optical sensor for biogenic amines in the following step since it displayed enhanced optical properties in comparison with complexes 1 and 3. The optical sensor for biogenic amines used silica microparticles as the immobilisation support and histamine as the analyte. The optical sensor had a limit of detection for histamine of 4.4 × 10-12 M, with a linear working range between 1.0 × 10-11 and 1.0 × 10-6 M (R2 = 0.9844). The sensor showed good reproducibility, with a low relative standard deviation (5.5 %). In addition, the sensor exhibited good selectivity towards histamine and cadaverine over other amines, such as 1,2-phenylenediamine, triethylamine, and trimethylamine. Recovery and real sample studies suggested that complex 2 could be a promising biogenic amine optical sensing material that can be applied in the food industry, especially in controlling the safety of food for it to remain fresh and healthy for consumption.
    Matched MeSH terms: Zinc Compounds/chemistry*
  3. Djearamane S, Lim YM, Wong LS, Lee PF
    PeerJ, 2019;7:e7582.
    PMID: 31579572 DOI: 10.7717/peerj.7582
    Background: Zinc oxide nanoparticles (ZnO NPs) are widely used in household and cosmetic products which imply an increased releasing of these particles into the environment, especially aquatic ecosystems, resulting in the need of assessing the potential toxic effects of ZnO NPS on the aquatic organisms, particularly on microalgae which form the base for food chain of aquatic biota. The present study has investigated the dose- and time-dependent cellular accumulation and the corresponding cytotoxic effects of increasing concentrations of ZnO NPs from 10-200 μg/mL on microalga Haematococcus pluvialis at an interval of 24 h for 96 h.

    Methods: The scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) was used to qualitatively detect the cellular accumulation of ZnO NPs in algal cells, while inductively coupled plasma optical emission spectrometry (ICP OES) was performed to quantify the cell associated-zinc in algal cells. The percentage of cell death, reduction in algal biomass, and loss in photosynthetic pigments were measured to investigate the cytotoxic effects of ZnO NPs on H. pluvialis. Extracellular and intracellular changes in algal cells resulted from the treatment of ZnO NPs were demonstrated through optical, scanning, and transmission electron microscopic studies.

    Results: SEM-EDX spectrum evidenced the accumulation of ZnO NPs in algal biomass and ICP OES results reported a significant (p < 0.05) dose- and time-dependent accumulation of zinc in algal cells from 24 h for all the tested concentrations of ZnO NPs (10-200 μg/mL). Further, the study showed a significant (p < 0.05) dose- and time-dependent growth inhibition of H. pluvialis from 72 h at 10-200 μg/mL of ZnO NPs. The morphological examinations revealed substantial surface and intracellular damages in algal cells due to the treatment of ZnO NPs.

    Discussion: The present study reported the significant cellular accumulation of ZnO NPs in algal cells and the corresponding cytotoxic effects of ZnO NPs on H. pluvialis through the considerable reduction in algal cell viability, biomass, and photosynthetic pigments together with surface and intracellular damages.

    Matched MeSH terms: Zinc; Zinc Oxide
  4. Lee SC, Tang MS, Easton AV, Devlin JC, Chua LL, Cho I, et al.
    PLoS Pathog, 2019 12;15(12):e1008066.
    PMID: 31841569 DOI: 10.1371/journal.ppat.1008066
    Helminth infection and dietary intake can affect the intestinal microbiota, as well as the immune system. Here we analyzed the relationship between fecal microbiota and blood profiles of indigenous Malaysians, referred to locally as Orang Asli, in comparison to urban participants from the capital city of Malaysia, Kuala Lumpur. We found that helminth infections had a larger effect on gut microbial composition than did dietary intake or blood profiles. Trichuris trichiura infection intensity also had the strongest association with blood transcriptional profiles. By characterizing paired longitudinal samples collected before and after deworming treatment, we determined that changes in serum zinc and iron levels among the Orang Asli were driven by changes in helminth infection status, independent of dietary metal intake. Serum zinc and iron levels were associated with changes in the abundance of several microbial taxa. Hence, there is considerable interplay between helminths, micronutrients and the microbiota on the regulation of immune responses in humans.
    Matched MeSH terms: Zinc/blood
  5. Lythell E, Suardíaz R, Hinchliffe P, Hanpaibool C, Visitsatthawong S, Oliveira ASF, et al.
    Chem Commun (Camb), 2020 Jun 23;56(50):6874-6877.
    PMID: 32432618 DOI: 10.1039/d0cc02520h
    MCR (mobile colistin resistance) enzymes catalyse phosphoethanolamine (PEA) addition to bacterial lipid A, threatening the "last-resort" antibiotic colistin. Molecular dynamics and density functional theory simulations indicate that monozinc MCR supports PEA transfer to the Thr285 acceptor, positioning MCR as a mono- rather than multinuclear member of the alkaline phosphatase superfamily.
    Matched MeSH terms: Zinc/chemistry*
  6. Harun NH, Mydin RBSMN, Sreekantan S, Saharudin KA, Basiron N, Seeni A
    J Biomater Sci Polym Ed, 2020 10;31(14):1757-1769.
    PMID: 32498665 DOI: 10.1080/09205063.2020.1775759
    The emerging polymer nanocomposites have received industrial interests in diverse fields because of their added value in metal oxide-based nanocomposites, such as titanium (TiO2) and zinc oxide (ZnO). Linear low-density polyethylene (LLDPE)-based polymer has recently generated a huge market in the healthcare industry. TiO2 and ZnO are well known for their instant photocatalytic killing of hospital-acquired infections, especially multidrug-resistant (MDR) pathogens. This study investigated the actions of LLDPE/TiO2/ZnO (1:3) nanocomposites in different weight% against two representative MDR pathogens, namely, methicillin-resistant Staphylococcus aureus (MRSA) and Klebsiella pneumonia (K.pneumoniae). Antibacterial activities were quantified according to international standard guidelines of CLSI MO2-A11 (static condition) and ASTM E-2149 (dynamic condition). Preliminary observation via a scanning electron microscope revealed that LLDPE matrix with TiO2/ZnO nanocomposites changed the bacterial morphology and reduced the bacterial adherence and biofilm formation. Furthermore, a high ZnO weight ratio killed both types of pathogens. The bactericidal potential of the nanocomposite is highlighted by the enhancements in photocatalytic activity, zinc ion release and reactive species, and bacteriostatic/bactericidal activity against bacterial growth. This study provides new insights into the MDR-bactericidal potential of LLDPE with TiO2/ZnO nanocomposites for targeted healthcare applications.
    Matched MeSH terms: Zinc; Zinc Oxide
  7. Nurfarhana Rosman, Nur Syazwani Abdul Malek, Mohamad Rusop Mahmood, Zuraida Khusaimi, Noor Asnida Asli
    Science Letters, 2020;14(2):47-57.
    MyJurnal
    Effect of different storage temperatures on physical and physiological changes of Golden Lily mango was investigated. Zinc oxide (ZnO) nanoparticles edible coating was prepared by sol-gel method and Golden Lily mangoes were dipped in the solution and stored at different (32℃, 27℃ and 5℃) temperatures for 7 days. The mangoes were characterized by Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), Fourier-transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) after 7 days of storage. Both the analysis of FESEM and EDX revealed the highest volume ratio of ZnO nanoparticles with a homogeneous dispersion throughout the mango peel surface is at 5℃. FTIR spectra revealed the absence of Zn–O bonding as metal oxides absorption is expected to be in the region below 700 cm-1. The mangoes stored at 5℃ delayed ripening, slowed down weight loss and found to be firmer than mangoes stored at 32℃ and 27℃.
    Matched MeSH terms: Zinc; Zinc Oxide
  8. Pathak R, Pathak A
    Biol Trace Elem Res, 2020 Aug 26.
    PMID: 32851540 DOI: 10.1007/s12011-020-02356-9
    Lithium is an integral drug used in the management of acute mania, unipolar and bipolar depression, and prophylaxis of bipolar disorders. Thyroid abnormalities have been associated with treatment with lithium. Zinc is an essential trace element that plays a role in several biological activities. Therefore, the present study was aimed at investigating the potential role of zinc in the thyroid gland following lithium administration to explore the role of zinc under such conditions. To achieve this goal, male Wistar rats (150-195 g) were divided into four groups: Group 1 animals were fed standard pellet feed and tap water ad lib; Group 2 rats were fed lithium in the form of lithium carbonate through diet at a concentration of 1.1 g/kg body weight; Group 3 animals received zinc treatment in the form of zinc sulfate (ZnSO4·7H2O) at a dose level of 227 mg/L mixed with drinking water of the animals; and Group 4 animals were given lithium and zinc in a similar manner as was given to the animals belonging to groups 2 and 4 respectively. The role of zinc on thyroid functions in lithium-treated rats was studied after 2, 4, and 8 weeks of different treatments. Zinc has been observed to have the capability to nearly normalize the altered 2-h uptake of 131I, biological and effective half-lives of 131I, and circulating T4 levels that were altered after lithium treatment. The present study concludes that zinc may be an effective agent in normalizing the adverse effects caused by lithium on thyroid functions.
    Matched MeSH terms: Zinc; Zinc Sulfate
  9. Razak MR, Aris AZ, Zakaria NAC, Wee SY, Ismail NAH
    Ecotoxicol Environ Saf, 2021 Mar 15;211:111905.
    PMID: 33453636 DOI: 10.1016/j.ecoenv.2021.111905
    The constant increase of heavy metals into the aqueous environment has become a contemporary global issue of concern to government authorities and the public. The study assesses the concentration, distribution, and risk assessment of heavy metals in freshwater from the Linggi River, Negeri Sembilan, Malaysia. Species sensitivity distribution (SSD) was utilised to calculate the cumulative probability distribution of toxicity from heavy metals. The aquatic organism's toxicity data obtained from the ECOTOXicology knowledgebase (ECOTOX) was used to estimate the predictive non-effects concentration (PNEC). The decreasing sequence of hazardous concentration (HC5) was manganese > aluminium > copper > lead > arsenic > cadmium > nickel > zinc > selenium, respectively. The highest heavy metal concentration was iron with a mean value of 45.77 μg L-1, followed by manganese (14.41 μg L-1) and aluminium (11.72 μg L-1). The mean heavy metal pollution index (HPI) value in this study is 11.52, implying low-level heavy metal pollutions in Linggi River. The risk quotient (RQ) approaches were applied to assess the potential risk of heavy metals. The RQ shows a medium risk of aluminium (RQm = 0.1125) and zinc (RQm = 0.1262); a low risk of arsenic (RQm = 0.0122) and manganese (RQm = 0.0687); and a negligible risk of cadmium (RQm = 0.0085), copper (RQm = 0.0054), nickel (RQm = 0.0054), lead (RQm = 0.0016) and selenium (RQm = 0.0012). The output of this study produces comprehensive pollution risk, thus provides insights for the legislators regarding exposure management and mitigation.
    Matched MeSH terms: Zinc/analysis
  10. Inayat-Hussain SH, Cohen GM, Cain K
    Cell Biol Toxicol, 1999;15(6):381-7.
    PMID: 10811533
    There is now a wealth of information regarding the apoptotic mode of cell death and its importance in toxicological studies in many mammalian organs including the liver. In this study, we investigated the modulatory effects of the heavy metal Zn2+ on transforming growth factor-beta1 (TGF-beta1)-induced apoptosis in primary rat hepatocytes. Apoptosis induced by TGF-beta1 (1 ng/ml) in hepatocytes was accompanied by nuclear condensation as assessed morphologically by staining with Hoechst 33258 and DNA cleavage as detected biochemically by in situ end-labeling, field inversion and conventional gel electrophoresis. Pretreatment with 100 micromol/L Zn2+ abrogated the nuclear condensation, in situ end-labeling, and DNA laddering in TGF-beta1-treated hepatocytes. Surprisingly, Zn2+ did not inhibit the formation of high-molecular-weight DNA fragments (30-50 kbp to 250-300 kbp). These data provide evidence that Zn2+ exerts its effects on the endonucleases that act downstream in the execution phase of TGF-beta1-induced apoptosis in hepatocytes.
    Matched MeSH terms: Zinc/toxicity*
  11. Hashim Z, Woodhouse L, King JC
    Int J Food Sci Nutr, 1996 Sep;47(5):383-90.
    PMID: 8889623
    Circulating zinc concentrations were measured in 73 healthy adult males and females 19-52 years of age who were volunteers for eight different metabolic studies at the University of California, Berkeley. The interindividual variation in the eight studies varied from 5 to 20%; the global coefficient of variation for all studies was 12 +/- 7% (mean +/- SD). The analysis of a reference plasma sample on six different days showed a mean coefficient of variation of 3.8%. Thus, only a small portion of the intraindividual variation is due to day-to-day analytical differences. There was no relationship between circulating zinc concentrations and age, height, or body mass index. Nor were there any significant differences due to gender. Information regarding dietary zinc and protein intakes was available from three-day weighed food intake records from 44 of the subjects. Plasma zinc concentrations were unrelated to the intake of either zinc or protein in those subjects. The results of this study show that the impact of age, gender, body size and dietary zinc or protein on circulating zinc concentrations are too small to be detected in the presence of the analytical and endogenous factors that influence plasma/serum zinc concentrations. Also, within a population of healthy adults, circulating zinc concentrations may vary by as much as 15%.
    Matched MeSH terms: Zinc/blood*
  12. Noordin MM, Zhang SS, Rahman SO, Haron J
    Vet Hum Toxicol, 2000 Oct;42(5):276-9.
    PMID: 11003117
    Samples of Brachiaria decumbens collected from 5 farms representing the Peninsular Malaysia were subjected to selected trace mineral and phytate analyses to explain the pathogenesis of B decumbens intoxication. Concentrations of Cu, Zn, Fe and Mo were comparable to other grasses while that of phytate was low. The molar ratios of Cu:Zn, Cu:Mo, and Cu:Fe warrant that Cu deficiency is involved in the toxicity of B decumbens. This might aggravate the development of photosensitization of unpigmented or lightly pigmented areas of affected animals. The Zn:phytate ratio could predispose to Zn deficiency during intoxication.
    Matched MeSH terms: Zinc/analysis
  13. Lim PE, Lee CK, Din Z
    Sci Total Environ, 1998 May 14;216(1-2):147-57.
    PMID: 9618930
    A study on the kinetics of accumulation and depuration of Zn, Cu, Pb and Cd by the oysters (Crassostrea iredalei and Crassostrea belcheri) cultured at two locations in the Merbok Estuary, Malaysia was conducted. A first-order kinetic model was employed to fit the experimental data in order to estimate the rate constants for uptake and elimination processes and to predict the bioconcentration factors (BCF). Among the four metals studied, only the Zn accumulation process could not be modelled using first-order kinetics. The elimination rate constants estimated from depuration data for C. iredalei are found to be much greater than those from accumulation data. The results suggest that the values of kinetic parameters and BCFs derived under conditions of both aqueous and dietary exposure are probably more site- than species-specific.
    Matched MeSH terms: Zinc/pharmacokinetics
  14. Aljuboury DA, Palaniandy P, Abdul Aziz HB, Feroz S, Abu Amr SS
    Water Sci Technol, 2016 Sep;74(6):1312-1325.
    PMID: 27685961
    The aim of this study is to investigate the performance of combined solar photo-catalyst of titanium oxide/zinc oxide (TiO2/ZnO) with aeration processes to treat petroleum wastewater. Central composite design with response surface methodology was used to evaluate the relationships between operating variables for TiO2 dosage, ZnO dosage, air flow, pH, and reaction time to identify the optimum operating conditions. Quadratic models for chemical oxygen demand (COD) and total organic carbon (TOC) removals prove to be significant with low probabilities (<0.0001). The obtained optimum conditions included a reaction time of 170 min, TiO2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), and pH 6.8 COD and TOC removal rates of 99% and 74%, respectively. The TOC and COD removal rates correspond well with the predicted models. The maximum removal rate for TOC and COD was 99.3% and 76%, respectively at optimum operational conditions of TiO2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), reaction time (170 min) and pH (6.8). The new treatment process achieved higher degradation efficiencies for TOC and COD and reduced the treatment time comparing with other related processes.
    Matched MeSH terms: Zinc Oxide/chemistry*
  15. Ooi TC, Chan KM, Sharif R
    Nutr Cancer, 2017 Feb-Mar;69(2):201-210.
    PMID: 28094570 DOI: 10.1080/01635581.2017.1265132
    Cancer is one of the major causes of death worldwide, and the incidence and mortality rates of cancer are expected to rise tremendously in the near future. Despite a better understanding of cancer biology and advancement in cancer management, current strategies in cancer treatment remain costly and ineffective. Hence, instead of putting more efforts to search for new cancer cures, attention has now been shifted to the development of cancer chemopreventive agents as a preventive measure for cancer formation. It is well known that neoplastic transformation of cells is multifactorial, and the occurrence of oxidative stress, chronic inflammation, and genomic instability events has been implicated in the carcinogenesis of cells. Zinc l-carnosine (ZnC), which is clinically used as gastric ulcer treatment in Japan, has been suggested to have the potential in preventing cancer development. Multiple studies have revealed that ZnC possesses potent antioxidant, anti-inflammatory, and genomic stability enhancement effects. Thus, this review provides some mechanistic insight into the antioxidant, anti-inflammatory, and genomic stability enhancement effects of ZnC in relevance to its chemopreventive potential.
    Matched MeSH terms: Zinc Compounds/pharmacology
  16. Yahya, N.A., Lui, J.L., Chong, K.W.A., Abu Kasim, N.H., Radzi, Z., Lim, C.M.
    Ann Dent, 2008;15(1):11-19.
    MyJurnal
    The objective of this study was to investigate the effect of various luting cement systems on bond strength of fibre-reinforced posts to root canal dentine. 40 extracted single rooted sound premolar teeth were root filled, decoronated and randomly divided into four groups. Fibre posts, Aestheti- Plus™ (Bisco,Inc. Schaumburg, IL, USA) were cemented using four luting cements: Group A (control): Elite 100® Zinc phosphate (GC Corp, Japan), Group B: Calibra ™ Esthetic Resin Cement (Dentsply Caulk, USA), Group C: RelyX ARC Adhesive Resin (3M ESPE), Group D: RelyX Unicem Aplicap (3M ESPE). Each root was sliced into 2 discs representing the coronal and middle portions of the root canal giving rise to 20 specimens per group. Bond strength was determined using push-out tests and data was analyzed using SPSS version 14.0. The mean bond strength of Group A to Aestheti-Plus™ post was 7.71 MPa (±2.51) and Group B was 5.69 MPa (±3.23). Group C exhibited the lowest mean bond strength, 4.29 MPa (±3.53) while the highest bond strength was obtained from Group D, 7.98 MPa (±2.61). One way ANOVA showed significant interaction between all groups (p=.OOI). Post-hoc Bonferroni test reve;iled that bond strength of Group C was significantly lower compared to Group A (p=.008) and D (p=.004). In conclusion, the mean bond strength of Aestheti- Plus™ post to root canal dentine was highest when cemented with RelyX Unicem resin cement followed by Elite 100® zinc phosphate cement, Calibra and RelyX ARC resin cements. However, the bond strengths of Cali bra and RelyX Unicem resin cements were not significantly different from Elite 100® zinc phosphate cement.
    Matched MeSH terms: Zinc Phosphate Cement; Zinc Compounds
  17. Chong LE, Jow TK
    Dent J Malaysia Singapore, 1967 Oct;7(2):44-51.
    PMID: 5247441
    Matched MeSH terms: Zinc Oxide-Eugenol Cement/therapeutic use
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