Displaying publications 1 - 20 of 28 in total

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  1. Ismail H, Shamsudin R, Abdul Hamid MA
    Mater Sci Eng C Mater Biol Appl, 2016 Jan 1;58:1077-81.
    PMID: 26478406 DOI: 10.1016/j.msec.2015.09.030
    β-wollastonite (β-CaSiO3) was synthesized from rice husk ash and calcium carbonate, and a study of the effects of the autoclaving and sintering steps is presented here. Autoclaving and sintering at 8h and 2h yielded the β-wollastonite phase in full, with improved crystallinity. Nucleation between rice husk ash and calcium oxide occurred around 135 °C, pressure 0.24 MPa, and growth proved to be more crystalline after the ripening period. For shorter processing times, and for both unsintered and unautoclaved samples, cristobalite and unstable tricalcium silicate phases were present. Crystallite size was increased by longer sintering times but reduced by longer autoclaving times. The β-wollastonite obtained had a random branch-like structure. In conclusion, the introduction of the autoclaving step successfully obtained β-wollastonite from a reaction between rice husk ash and calcium oxide.
  2. Zheng X, Abdul Hamid MA, Hou Y
    Heliyon, 2024 May 15;10(9):e30048.
    PMID: 38726191 DOI: 10.1016/j.heliyon.2024.e30048
    The identification of accounting fraud is an important measure to safeguard the interests of stakeholders and ensure the long-term development of the company. The current traditional methods for identifying accounting fraud rely on manual review and judgment, lacking objectivity and accuracy. In order to improve the accuracy of accounting fraud identification, improve identification efficiency and objectivity, this article combines smart city information technology to conduct in-depth research on data mining algorithms for accounting fraud identification. This article first provides a brief overview of smart cities and information technology, then introduces the basic theory of accounting fraud identification, and finally implements accounting fraud identification through k-means clustering mining algorithm. The data is divided into k clusters, and abnormal clusters are identified by checking the characteristics and attributes of each cluster. Compared with traditional rule-based and pattern based methods, this approach can more flexibly adapt to different types and forms of fraud, and can discover unknown patterns of fraud. In the experiment, this article used electronic data collection, analysis, and retrieval systems on the websites of the Shanghai Stock Exchange and Shenzhen Stock Exchange to collect 641 annual reports and financial characteristics from 62 listed companies that engaged in financial statement fraud and 84 companies that were not reported to have financial statement fraud from 2012 to 2021 as test samples. The results were tested and analyzed from several aspects, including the number of misjudgments, misjudgment rate, and ROC curve. The final test results show that compared to traditional accounting fraud identification methods, the comprehensive misjudgment rate of data mining algorithms based on smart cities has decreased by 3 %. The conclusion indicates that data mining algorithms used in smart city information technology to identify accounting fraud can help improve the accuracy of accounting fraud, improve audit objectivity and effectiveness.
  3. Abedini A, Daud AR, Abdul Hamid MA, Kamil Othman N
    PLoS One, 2014;9(3):e90055.
    PMID: 24608715 DOI: 10.1371/journal.pone.0090055
    Colloidal Fe3O4 nanoparticles were synthesized using a gamma-radiolysis method in an aqueous solution containing iron chloride in presence of polyvinyl alcohol and isopropanol as colloidal stabilizer and hydroxyl radical scavenger, respectively. Gamma irradiation was carried out in a 60Co gamma source chamber at different absorbed doses. Increasing the radiation dose above a certain critical dose (100 kGy) leads to particle agglomeration enhancement, and this can influence the structure and crystallinity, and consequently the magnetic properties of the resultant particles. The optimal condition for formation of Fe3O4 nanoparticles with a uniform and narrow size distribution occurred at a dose of 100 kGy, as confirmed by X-ray diffractometry and transmission electron microscopy. A vibrating sample magnetometry study showed that, when radiation dose increased, the saturation and remanence magnetization decreased, whereas the coercivity and the remanence ratio increased. This magnetic behavior results from variations in crystallinity, surface effects, and particle size effects, which are all dependent on the radiation dose. In addition, Fourier transform infrared spectroscopy was performed to investigate the nature of the bonds formed between the polymer chains and the metal surface at different radiation doses.
  4. Andiesta NS, Hamid MA, Lee K, Pau A
    JMIR Res Protoc, 2018 Jun 06;7(6):e10053.
    PMID: 29875086 DOI: 10.2196/10053
    BACKGROUND: In 2012, nearly 4000 children in Malaysia were referred to hospital pediatric dental services due to dental caries. Recent research has reported the effectiveness of dental home visits in preventing caries development in young children. Dental home visits (DHVs) are described as an ongoing relationship between the dentist and their patients, providing all aspects of a preventive oral health care program in the presence of the parents at home.

    OBJECTIVE: The objective of this study is to evaluate the cost-effectiveness of dental home visits and oral health information, in the form of educational leaflets, in preventing new caries development in young children, compared to those receiving only educational leaflets over a period of two years. Cost-effectiveness analysis will be used to evaluate the cost-effectiveness of dental home visits.

    METHODS: This is a collaborative project with the Oral Health Division of the Ministry of Health Malaysia. The Oral Health Division will provide access to a subsample from the National Oral Health of Preschoolers Survey which was carried out in 2015. The population of interest is children aged 5 and 6 years from kindergartens in the Selangor state of Malaysia. The study adopted a societal perspective for cost-effectiveness analysis and all types of resources that are of value to society will be included in analyzing the costs; such as cost to the patient, cost to the provider or institution, and indirect costs because of loss of productivity.

    RESULTS: The trial has been approved by the International Medical University Malaysia's Joint Research and Ethics Committee (Project ID: IMU R157-2014 [File III - 2016]). This trial is currently recruiting participants.

    CONCLUSIONS: The number of young children in Malaysia who have been referred to the hospital children's dentistry service for severe caries is disturbing. The cost of dental treatment in young children is high due to the severity of the caries which require an aggressive treatment, and the need for general anesthesia or sedation. This study will provide information on the cost and effectiveness of DHVs in caries prevention of young children in Malaysia.

    REGISTERED REPORT IDENTIFIER: RR1-10.2196/10053.

  5. Elochukwu H, Sia LKSL, Gholami R, Hamid MA
    Data Brief, 2018 Dec;21:972-979.
    PMID: 30426054 DOI: 10.1016/j.dib.2018.10.055
    Data presented in this article focused on the application of Methyl Ester Sulphonate (MES) surfactant and nanopolystyrene in water based drilling fluid. Data from rheology study using Bingham and Power law models showed that the synergy of MES and nanopolystyrene improved the formulated drilling fluid. Filtration study under LPLT and HPHT conditions showed that MES and nanopolystyrene drilling fluid reduced filtration loss by 50.7% at LPLT and 61.1% at HPHT conditions. These filtration data were validated by filter cake permeability and scanning electron microscope images.
  6. Lim TO, Bakri R, Morad Z, Hamid MA
    Diabetes Care, 2002 Dec;25(12):2212-7.
    PMID: 12453963 DOI: 10.2337/diacare.25.12.2212
    OBJECTIVE: Bimodality in blood glucose (BG) distribution has been demonstrated in several populations with a high prevalence of diabetes and obesity. However, other population studies had not found bimodality, thus casting doubt on its universality. We address this question in four ethnic populations-namely Malay, Chinese, Indian, and the indigenous people of Borneo.

    RESEARCH DESIGN AND METHODS: A national health survey was conducted in Malaysia in 1996. A total of 18,397 subjects aged > or =30 years had post-challenge BG measurements taken. To test whether BG was consistent with a bimodal distribution, we fitted unimodal normal and skewed distribution as well a mixture of two normal distributions to the data by age and ethnic groups.

    RESULTS: Age-specific prevalence of diabetes varied from 1.3 to 26.3%. In all ethnic/age groups, the bimodal model fitted the log BG data better (likelihood ratio tests, all P values <0.001).

    CONCLUSIONS: Bimodality in BG distribution is demonstrable even in populations with a very low prevalence of diabetes and obesity. Previous studies that found unimodality had failed to detect the second mode because of inadequate sample size, bias due to treatment of subjects with known diabetes, and inclusion of subjects with type 1 diabetes in the sample. Bimodality implies that diabetes is a distinct entity rather than an arbitrarily defined extreme end of a continuously distributed measurement.
  7. Shamsudin R, Abdul Azam F', Abdul Hamid MA, Ismail H
    Materials (Basel), 2017 Oct 17;10(10).
    PMID: 29039743 DOI: 10.3390/ma10101188
    The aim of this study was to prepare β-wollastonite using a green synthesis method (autoclaving technique) without organic solvents and to study its bioactivity. To prepare β-wollastonite, the precursor ratio of CaO:SiO₂ was set at 55:45. This mixture was autoclaved for 8 h and later sintered at 950 °C for 2 h. The chemical composition of the precursors was studied using X-ray fluorescence (XRF), in which rice husk ash consists of 89.5 wt % of SiO₂ in a cristobalite phase and calcined limestone contains 97.2 wt % of CaO. The X-ray diffraction (XRD) patterns after sintering showed that only β-wollastonite was detected as the single phase. To study its bioactivity and degradation properties, β-wollastonite samples were immersed in simulated body fluid (SBF) for various periods of time. Throughout the soaking period, the molar ratio of Ca/P obtained was in the range of 1.19 to 2.24, and the phase detected was amorphous calcium phosphate, which was confirmed by scanning electron microscope with energy dispersive X-ray analysis (SEM/EDX) and XRD. Fourier-transform infrared spectroscopy (FTIR) analysis indicated that the peaks of the calcium and phosphate ions increased when an amorphous calcium phosphate layer was formed on the surface of the β-wollastonite sample. A cell viability and proliferation assay test was performed on the rice husk ash, calcined limestone, and β-wollastonite samples by scanning electron microscope. For heavy metal element evaluation, a metal panel that included As, Cd, Pb, and Hg was selected, and both precursor and β-wollastonite fulfilled the requirement of an American Society for Testing and Materials (ASTM F1538-03) standard specification. Apart from that, a degradation test showed that the loss of mass increased incrementally as a function of soaking period. These results showed that the β-wollastonite materials produced from rice husk ash and limestone possessed good bioactivity, offering potential for biomedical applications.
  8. Lim CH, Rasti B, Sulistyo J, Hamid MA
    Heliyon, 2021 Feb;7(2):e06305.
    PMID: 33665455 DOI: 10.1016/j.heliyon.2021.e06305
    Transglycosylation is the in-vivo or in-vitro process of transferring glycosyl groups from a donor to an acceptor, which is usually performed by enzymatic reactions because of their simplicity, low steric hindrance, high region-specificity, low production cost, and mild processing conditions. One of the enzymes commonly used in the transglycosylation reaction is cyclodextrin glucanotransferase (CGTase). The transglycosylated products, catalyzed by CGTase, are widely used in food additives, supplements, and personal care and cosmetic products. This is due to improvements in the solubility, stability, bioactivity and length of the synthesized products. This paper's focus is on the importance of enzymes used in the transglycosylation reaction, their characteristics and mechanism of action, sources and production yield, and donor and acceptor specificities. Moreover, the influence of intrinsic and extrinsic factors on the enzymatic reaction, catalysis of glycosidic linkages, and advantages of CGTase transglycosylation reactions are discussed in detail.
  9. Bin Hamid MA, Hoe Guan B, Tim CK, Soleimani H
    RSC Adv, 2024 Nov 04;14(48):35671-35678.
    PMID: 39524085 DOI: 10.1039/d4ra04500a
    The utilization of superparamagnetic iron oxide nanofluids in enhanced oil recovery (EOR) has gained attention due to their ability to alter the interfacial tension (IFT) of reservoir rocks. However, the influence of electromagnetic (EM) waves on these nanofluids, particularly when doped with manganese (Mn), remains underexplored. The interaction mechanisms between EM waves and Mn-doped Fe3O4 nanofluids are not well understood, limiting their application in EOR. This study aimed to investigate the effects of EM waves on Mn-doped superparamagnetic iron oxide nanofluids and to assess the potential for enhancing oil recovery by measuring their IFT. Mn-doped Fe3O4 nanoparticles were synthesized using a co-precipitation method and stabilized with ascorbic acid. Density functional theory (DFT) was employed to study the Mn-dopant site selectivity within the Fe3O4 lattice. Helmholtz coils generated uniform EM fields and interfacial tension (IFT) measurements were conducted under applied EM waves generated under both direct current (DC) and alternating current (AC) conditions. DFT calculations indicated a preference for Mn dopants in specific lattice sites, while the experimental results showed that both DC- and AC-generated sinusoidal EM waves could reduce the IFT of the Mn-doped nanofluids, suggesting their improved EOR potential. These findings provide new insights into the application of EM waves in nanofluid-based EOR.
  10. Azad MA, Shah-E-Alam M, Hamid MA, Rafii MY, Malek MA
    ScientificWorldJournal, 2014;2014:589586.
    PMID: 24737982 DOI: 10.1155/2014/589586
    A study was performed using 6 × 6 F1 diallel population without reciprocals to assess the mode of inheritance of pod yield and related traits in groundnut with imposed salinity stress. Heterosis was found for pod number and yield. Data on general and specific combining ability (gca and sca) indicated additive and nonadditive gene actions. The gca: sca ratios were much less than unity suggesting predominant role of nonadditive gene effects. Cultivars "Binachinabadam-2" and "Dacca-1" and mutant M6/25/64-82 had the highest, second highest, and third highest pod number, as well as gca values, respectively. These two cultivars and another mutant M6/15/70-19 also had the highest, second highest, and third highest pod yield, as well as gca values, respectively. Therefore, "Dacca-1", "Binachinabadam-2", M6/25/64-82, and M6/15/70-19 could be used as source of salinity tolerance. Cross combinations showing high sca effects arising from parents with high and low gca values for any trait indicate the influence of nonadditive genes on their expression. Parents of these crosses can be used for biparental mating or reciprocal recurrent selection for developing high yielding varieties. Crosses with high sca effects having both parents with good gca effects could be exploited by pedigree breeding to get transgressive segregants.
  11. Abedini A, Daud AR, Abdul Hamid MA, Kamil Othman N, Saion E
    Nanoscale Res Lett, 2013;8(1):474.
    PMID: 24225302 DOI: 10.1186/1556-276X-8-474
    This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose.
  12. Ibrahim A, Lee KY, Kanoo LL, Tan CH, Hamid MA, Hamedon NM, et al.
    Spine (Phila Pa 1976), 2013 Mar 1;38(5):419-24.
    PMID: 22914700 DOI: 10.1097/BRS.0b013e31826ef594
    Cross-sectional study.
  13. Oh MJ, Hamid MA, Ngadiran S, Seo YK, Sarmidi MR, Park CS
    Arch. Dermatol. Res., 2011 Apr;303(3):161-70.
    PMID: 20981431 DOI: 10.1007/s00403-010-1089-5
    Ficus deltoidea (Mas cotek) water extract has been widely used for woman health in Malaysia. Our investigation focused to identify anti-melanogenic efficacy of F. deltoidea since it has been known to have strong anti-oxidant activities. Anti-melanogenic effect of F. deltoidea extract was analyzed using cultured B16F1 melanoma cells. Cytotoxicity of the extract was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and determined the highest concentration of the extract that did not affect cell viability as 0.1% (w/v). α-MSH-induced melanin synthesis was significantly inhibited with dose-dependent manner by treatment of F. deltoidea leave extract, which was comparable to that of kojic acid. The extract directly inhibited mushroom tyrosinase activity and intracellular tyrosinase activity of B16F1 as well. The inhibition of intracellular tyrosinase activity was found to be exerted at the protein expression level when analyzed by immunoblot and tyrosinase zymography. The expression of microphthalmia-associated transcription factor (MITF) was also reduced by the F. deltoidea extract. In conclusion, F. deltoidea extract has strong anti-melanogenic activity that is exerted by direct inhibition of tyrosinase enzyme activity and by down-regulation of the expression of genes involved in the melanogenesis pathways. Collectively, data shown in this study strongly suggest that F. deltoidea extract has potential to be used as a novel depigmenting agent for cosmetics.
  14. Al-Khalqi EM, Abdul Hamid MA, Al-Hardan NH, Keng LK
    Sensors (Basel), 2021 Mar 17;21(6).
    PMID: 33802968 DOI: 10.3390/s21062110
    For highly sensitive pH sensing, an electrolyte insulator semiconductor (EIS) device, based on ZnO nanorod-sensing membrane layers doped with magnesium, was proposed. ZnO nanorod samples prepared via a hydrothermal process with different Mg molar ratios (0-5%) were characterized to explore the impact of magnesium content on the structural and optical characteristics and sensing performance by X-ray diffraction analysis (XRD), atomic force microscopy (AFM), and photoluminescence (PL). The results indicated that the ZnO nanorods doped with 3% Mg had a high hydrogen ion sensitivity (83.77 mV/pH), linearity (96.06%), hysteresis (3 mV), and drift (0.218 mV/h) due to the improved crystalline quality and the surface hydroxyl group role of ZnO. In addition, the detection characteristics varied with the doping concentration and were suitable for developing biomedical detection applications with different detection elements.
  15. Chin GS, Todo H, Kadhum WR, Hamid MA, Sugibayashi K
    Chem Pharm Bull (Tokyo), 2016;64(12):1666-1673.
    PMID: 27904075
    The current investigation evaluated the potential of proniosome as a carrier to enhance skin permeation and skin retention of a highly lipophilic compound, α-mangostin. α-Mangostin proniosomes were prepared using the coacervation phase seperation method. Upon hydration, α-mangostin loaded niosomes were characterized for size, polydispersity index (PDI), entrapment efficiency (EE) and ζ-potential. The in vitro permeation experiments with dermis-split Yucatan Micropig (YMP) skin revealed that proniosomes composed of Spans, soya lecithin and cholesterol were able to enhance the skin permeation of α-mangostin with a factor range from 1.8- to 8.0-fold as compared to the control suspension. Furthermore, incorporation of soya lecithin in the proniosomal formulation significantly enhanced the viable epidermis/dermis (VED) concentration of α-mangostin. All the proniosomal formulations (except for S20L) had significantly (p<0.05) enhanced deposition of α-mangostin in the VED layer with a factor range from 2.5- to 2.9-fold as compared to the control suspension. Since addition of Spans and soya lecithin in water improved the solubility of α-mangostin, this would be related to the enhancement of skin permeation and skin concentration of α-mangostin. The choice of non-ionic surfactant in proniosomes is an important factor governing the skin permeation and skin retention of α-mangostin. These results suggested that proniosomes can be utilized as a carrier for highly lipophilic compound like α-mangostin for topical application.
  16. Al-Hardan NH, Abdul Hamid MA, Shamsudin R, Othman NK, Kar Keng L
    Sensors (Basel), 2016 Jun 29;16(7).
    PMID: 27367693 DOI: 10.3390/s16071004
    Zinc oxide (ZnO) nanorods (NRs) have been synthesized via the hydrothermal process. The NRs were grown over a conductive glass substrate. A non-enzymatic electrochemical sensor for hydrogen peroxide (H₂O₂), based on the prepared ZnO NRs, was examined through the use of current-voltage measurements. The measured currents, as a function of H₂O₂ concentrations ranging from 10 μM to 700 μM, revealed two distinct behaviours and good performance, with a lower detection limit (LOD) of 42 μM for the low range of H₂O₂ concentrations (first region), and a LOD of 143.5 μM for the higher range of H₂O₂ concentrations (second region). The prepared ZnO NRs show excellent electrocatalytic activity. This enables a measurable and stable output current. The results were correlated with the oxidation process of the H₂O₂ and revealed a good performance for the ZnO NR non-enzymatic H₂O₂ sensor.
  17. Lim K, Abdul Hamid MA, Shamsudin R, Al-Hardan NH, Mansor I, Chiu W
    Materials (Basel), 2016 Apr 20;9(4).
    PMID: 28773425 DOI: 10.3390/ma9040300
    In this paper, we address the synthesis of nano-coalesced microstructured zinc oxide thin films via a simple thermal evaporation process. The role of synthesis temperature on the structural, morphological, and optical properties of the prepared zinc oxide samples was deeply investigated. The obtained photoluminescence and X-ray photoelectron spectroscopy outcomes will be used to discuss the surface structure defects of the prepared samples. The results indicated that the prepared samples are polycrystalline in nature, and the sample prepared at 700 °C revealed a tremendously c-axis oriented zinc oxide. The temperature-driven morphological evolution of the zinc oxide nano-coalesced microstructures was perceived, resulting in transformation of quasi-mountain chain-like to pyramidal textured zinc oxide with increasing the synthesis temperature. The results also impart that the sample prepared at 500 °C shows a higher percentage of the zinc interstitial and oxygen vacancies. Furthermore, the intensity of the photoluminescence emission in the ultraviolet region was enhanced as the heating temperature increased from 500 °C to 700 °C. Lastly, the growth mechanism of the zinc oxide nano-coalesced microstructures is discussed according to the reaction conditions.
  18. Che Musa AA, Husin MH, Aziz ME, A Hamid MA, Zon EM
    Cureus, 2024 Jul;16(7):e65573.
    PMID: 39192893 DOI: 10.7759/cureus.65573
    Mullerian duct anomalies are congenital abnormalities involving the female genital systems. A double uterus or uterine didelphys is one of the uterine duplication anomalies that result from impaired fusion with regard to the Mullerian ducts. The uterine didelphys can be diagnosed earlier in symptomatic patients. However, the diagnosis can be delayed or the patients may remain undiagnosed throughout their lifetime if asymptomatic. Pregnant women with uterine didelphys are at a greater risk for spontaneous miscarriage, malposition, premature labor, and cervical incompetence. Uterine didelphys are also associated with renal anomalies such as renal agenesis or duplex kidneys. We present a case of a 24-year-old primigravida who had a spontaneous pregnancy and underwent a lower segment cesarean section (LSCS) after a failed external cephalic version for the breech fetal position. The uterine didelphys was diagnosed postnatally. Her condition was associated with right renal agenesis and concomitant left renal calculus.
  19. Khoo EM, Sararaks S, Lee WK, Liew SM, Cheong AT, Abdul Samad A, et al.
    Asia Pac J Public Health, 2015 Sep;27(6):670-7.
    PMID: 25563351 DOI: 10.1177/1010539514564007
    This study aimed to develop an intervention to reduce medical errors and to determine if the intervention can reduce medical errors in public funded primary care clinics. A controlled interventional trial was conducted in 12 conveniently selected primary care clinics. Random samples of outpatient medical records were selected and reviewed by family physicians for documentation, diagnostic, and management errors at baseline and 3 months post intervention. The intervention package comprised educational training, structured process change, review methods, and patient education. A significant reduction was found in overall documentation error rates between intervention (Pre 98.3% [CI 97.1-99.6]; Post 76.1% [CI 68.1-84.1]) and control groups (Pre 97.4% [CI 95.1-99.8]; Post 89.5% [85.3-93.6]). Within the intervention group, overall management errors reduced from 54.0% (CI 49.9-58.0) to 36.6% (CI 30.2-43.1) and medication error from 43.2% (CI 39.2-47.1) to 25.2% (CI 19.9-30.5). This low-cost intervention was useful to reduce medical errors in resource-constrained settings.
  20. Azmi NE, Ramli NI, Abdullah J, Abdul Hamid MA, Sidek H, Abd Rahman S, et al.
    Biosens Bioelectron, 2015 May 15;67:129-33.
    PMID: 25113659 DOI: 10.1016/j.bios.2014.07.056
    A novel optical detection system consisting of combination of uricase/HRP-CdS quantum dots (QDs) for the determination of uric acid in urine sample is described. The QDs was used as an indicator to reveal fluorescence property of the system resulting from enzymatic reaction of uricase and HRP (horseradish peroxidase), which is involved in oxidizing uric acid to allaintoin and hydrogen peroxide. The hydrogen peroxide produced was able to quench the QDs fluorescence, which was proportional to uric acid concentration. The system demonstrated sufficient activity of uricase and HRP at a ratio of 5U:5U and pH 7.0. The linearity of the system toward uric acid was in the concentration range of 125-1000 µM with detection limit of 125 µM.
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