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Fulltext Non-evaporative method to remove high boiling point solvent (ethyl lactate) from palm oil extract at atmospheric conditions

Kua, Y. L., Gan, S., Morris, A., Ng, H. K.

International Food Research Journal, 2018;25(101):97-103.
MyJurnal

Ethyl lactate was demonstrated as a green and efficient agrochemical solvent to concentrate phytonutrients such as carotenes and tocols in palm oil. However, the removal of this solvent from the extract is difficult and expensive due to its very high boiling point and low volatility. Heating at high temperature in an effort to evaporate the solvent is undesirable even under reduced pressure as the extracted phytonutrients are heat-sensitive compounds. In this paper, a non-evaporative method using only water was proposed for the first time to remove the solvent at atmospheric conditions based on its solubility difference instead of the vapour pressure difference. The proposed method was proved to be more effective, faster and cheaper as compared to conventional approaches such as rotary evaporation, freeze drying and vacuum drying.
Validation of a high-performance liquid chromatography method for tramadol and o-desmethyltramadol in human plasma using solid-phase extraction

Gan SH, Ismail R

J Chromatogr B Biomed Sci Appl, 2001 Aug 15;759(2):325-35.
PMID: 11499486

An HPLC system using solid-phase extraction and HPLC with UV detection has been validated in order to determine tramadol and o-desmethyltramadol (M1) concentrations in human plasma. The method developed was selective and linear for concentrations ranging from 50 to 3,500 ng/ml (tramadol) and 50 to 500 ng/ml (M1) with mean recoveries of 94.36 +/- 12.53% and 93.52 +/- 7.88%, respectively. Limit of quantitation (LOQ) was 50 ng/ml. For tramadol, the intra-day accuracy ranged from 95.48 to 114.64% and the inter-day accuracy, 97.21 to 103.24%. Good precision (0.51 and 18.32% for intra- and inter-day, respectively) was obtained at LOQ. The system has been applied to determine tramadol concentrations in human plasma samples for a pharmacokinetic study.
Modified Fenton oxidation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils and the potential of bioremediation as post-treatment

Venny, Gan S, Ng HK

Sci Total Environ, 2012 Mar 1;419:240-9.
PMID: 22285087 DOI: 10.1016/j.scitotenv.2011.12.053

This work focuses on the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil using modified Fenton (MF) treatment coupled with a novel chelating agent (CA), a more effective technique among currently available technologies. The performance of MF treatment to promote PAH oxidation in artificially contaminated soil was investigated in a packed column with a hydrogen peroxide (H(2)O(2)) delivery system simulating in-situ soil flushing which is more representative of field conditions. The effectiveness of process parameters H(2)O(2)/soil, Fe(3+)/soil, CA/soil weight ratios and reaction time were studied using a 2(4) three level factorial design experiments. An optimised operating condition of the MF treatment was observed at H(2)O(2)/soil 0.05, Fe(3+)/soil 0.025, CA/soil 0.04 and 3h reaction time with 79.42% and 68.08% PAH removals attainable for the upper and lower parts of the soil column respectively. The effects of natural attenuation and biostimulation process as post-treatment in the remediation of the PAH-contaminated soil were also studied. In all cases, 3-aromatic ring PAH (phenanthrene) was more readily degraded than 4-aromatic ring PAH (fluoranthene) regardless of the bioremediation approach. The results revealed that both natural attenuation and biostimulation could offer remarkable enhancement of up to 6.34% and 9.38% in PAH removals respectively after 8 weeks of incubation period. Overall, the results demonstrated that combined inorganic CA-enhanced MF treatment and bioremediation serves as a suitable strategy to enhance soil quality particularly to remediate soils heavily contaminated with mixtures of PAHs.
CYP3A4 genetic polymorphism influences repaglinide's pharmacokinetics

Ruzilawati AB, Gan SH

Pharmacology, 2010;85(6):357-64.
PMID: 20523106 DOI: 10.1159/000302731

AIM: To investigate the effects of CYP3A4 and CYP2C8 enzymes on repaglinide's pharmacokinetics in healthy Malaysian subjects.
METHODS: Subjects (n = 121) received oral repaglinide (4 mg). Blood samples were taken at 0, 30, 60, 120, 180 and 240 min and serum concentrations of repaglinide were determined using high-performance liquid chromatography. Subjects were also genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for CYP3A4*4, *5 and*18 and by an allele-specific multiplex PCR for CYP2C8*2, *3, *4 and *5 alleles.
RESULTS: The allele frequencies of CYP2C8*1, *2, *3, *4 and *5 were 95.04, 0.40, 0.40, 0 and 4.13%, respectively. The frequencies of the CYP3A4*1, *4, *5 and *18 alleles were 97.93, 0, 0 and 2.07%, respectively. CYP2C8 and CYP3A4 genotypes were not significantly associated with repaglinide's blood glucose-lowering effect. However, the CYP3A4 genotype significantly influenced some of repaglinide's pharmacokinetics, where the mean elimination rate constant was 44.0% lower (p = 0.04) and the mean half-life was 33.8% higher (p = 0.04) in subjects with the CYP3A4*1/*18 genotype as compared to those with the normal CYP3A4*1/*1 genotype. This result confirms that CYP3A4 plays a large role in metabolizing repaglinide.
CONCLUSION: Genetic polymorphisms of CYP3A4, specifically CYP3A4*18, play a major role in contributing to the interindividual variability in repaglinide's pharmacokinetics.
Microwave-stimulated fixation for electron microscopy using a domestic microwave oven

Ng KH, Gan SK

Malays J Pathol, 1990 Jun;12(1):27-33.
PMID: 2090887

We investigated microwave-stimulated fixation of tissues for transmission electron microscopy using a domestic microwave oven operating at a frequency of 2.45 GHz with an output power of 500W. Microwave-stimulated fixation, in 4% glutaraldehyde, of fresh rat kidney, liver, heart and brain tissues was compared to conventional fixation. Human renal biopsies were similarly studied. Electron microscopy showed excellent ultrastructural preservation comparable to that obtained by conventional fixation. The optimal temperature range for microwave-stimulated fixation was found to lie between 50 degrees C and 55 degrees C. Our results indicate that microwave-stimulated fixation is a rapid and reproducible technique and can be effectively applied to routine diagnostic pathology.
Antithrombotic effects of hydroxychloroquine in a pregnant patient with Antiphospholipid syndrome and recurrent venous thromboembolism

Gan SP, Ong SG

Med J Malaysia, 2017 04;72(2):124-125.
PMID: 28473677 MyJurnal

A pregnant woman with antiphospholipid syndrome presented with repeated venous thromboembolism (VTE) in the first and second trimesters of pregnancy despite receiving combination therapy with low-molecular-weight heparin and aspirin. The addition of hydroxychloroquine prevented further VTE recurrence, thus demonstrating its potential antithrombotic effects.
Correlation of Serum Estradiol and Duration of Anastrazole Therapy with Treatment Related Adverse Effects Among Postmenopausal Breast Cancer Women: A Cross-sectional Study

Abubakar MB, Gan SH

Niger J Physiol Sci, 2017 Dec 30;32(2):219-225.
PMID: 29485645

Although anastrozole (Anas) plays a key role in the management of endocrine sensitive post-menopausal (PM) breast cancer (BC), there is much variability in its efficacy and tolerability. Anas-associated musculoskeletal symptoms (MS) and other adverse reactions, such as hot flashes (HF) and vaginal dryness/dyspareunia (VDD), are common and can affect the quality of life of BC patients, even sometimes leading to treatment withdrawal. The aim of this study was to determine the clinical and demographic factors associated with these adverse events. This is a cross-sectional study in estrogen receptor (ER) positive PM women (n = 92) with stages I to III BC receiving Anas. Multivariate analyses were performed to investigate the factors associated with Anas-induced adverse effects such as MS, HF and VDD. A serum estradiol concentration was undetectable (< 36.7 pmol/L) in 68.1% of patients but was detectable within a normal range (>36.7-88.1 pmol/L) in the other 31.9% of patients, and this group was found to have a lower odds of having at least one adverse effect (AE) compared to those with undetectable levels [adjusted odds ratio (AOR) 0.12, 95% confidence interval (CI) 0.02 to 0.64, p = 0.013]. Women with grades II and III tumors and a family history of BC had a higher odds of AE (grade II: AOR 12.22, CI 1.48 to 100.80, p = 0.020; grade III: AOR 12.95, CI 1.25 to 134.33, p = 0.032) and VDD (AOR 5.99, CI 1.30 to 27.52, p = 0.021), respectively. Patients who received Anas treatment for more than one year had a higher odds of VDD (one to three years: AOR 34.57, CI 3.86, 309.50, p = 0.002; more than 3 years: AOR 27.90, CI 2.21 to 351.84, p = 0.010). Advanced age also lowered the odds of HF (AOR 0.90, CI 0.83 to 1.00, p = 0.049). In conclusion, patients' hormonal environments and durations of Anas treatment may play a role in developing Anas-induced adverse effects.
Evaluation of in situ catalysed hydrogen peroxide propagation (CHP) for phenanthrene and fluoranthene removals from soil and its associated impacts on soil functionality

Venny, Gan S, Ng HK

Environ Sci Pollut Res Int, 2014 Feb;21(4):2888-97.
PMID: 24151025 DOI: 10.1007/s11356-013-2207-7

Extensive contamination of soils by highly recalcitrant contaminants such as polycyclic aromatic hydrocarbons (PAHs) is an environmental problem arising from rapid industrialisation. This work focusses on the remediation of soil contaminated with 3- and 4-aromatic ring PAHs (phenanthrene (PHE) and fluoranthene (FLUT)) through catalysed hydrogen peroxide propagation (CHP). In the present work, the operating parameters of the CHP treatment in packed soil column was optimised with central composite design (H2O2/soil 0.081, Fe(3+)/soil 0.024, sodium pyrophosphate (SP)/soil 0.024, pH of SP solution 7.73). The effect of contaminant aging on PAH removals was also investigated. Remarkable oxidative PAH removals were observed for the short aging and extended aging period (up to 86.73 and 70.61 % for PHE and FLUT, respectively). The impacts of CHP on soil biological, chemical and physical properties were studied for both spiked and aged soils. Overall, the soil functionality analyses after the proposed operating condition demonstrated that the values for soil respiration, electrical conductivity, pH and iron precipitation fell within acceptable limits, indicating the compatibility of the CHP process with land restoration.
Antioxidative/Antimicrobial effects of galangal and alpha-tocopherol in minced beef

Cheah PB, Gan SP

J Food Prot, 2000 Mar;63(3):404-7.
PMID: 10716573

The antioxidant and microbial stabilities of galangal (Alpinia galanga) extract in raw minced beef were examined at 4 +/- 1 degree C. Raw minced beef containing galangal extracts (0 to 0.10%, wt/wt) were prepared. Lipid oxidation during refrigerated storage was assessed by monitoring malonaldehyde formation, using the thiobarbituric acid reactive substances method. In minced beef, added galangal extract improved oxidative stability. Galangal extract at higher concentrations of 0.05% and 0.10% (wt/wt) were also found to extend the shelf-life of minced beef. Addition of alpha-tocopherol (0.02%, wt/wt) to galangal extract (0.05%, wt/wt) were observed to increase the oxidative but not the microbial stability of minced beef during the storage of 7 days. Galangal extract may prove useful in inhibiting lipid oxidation and increasing microbial stability of minced meat.
Investigation of the impacts of ethyl lactate based Fenton treatment on soil quality for polycyclic aromatic hydrocarbons (PAHs)-contaminated soils

Gan S, Yap CL, Ng HK, Venny

J Hazard Mater, 2013 Nov 15;262:691-700.
PMID: 24121640 DOI: 10.1016/j.jhazmat.2013.09.023

This study aims to investigate the impacts of ethyl lactate (EL) based Fenton treatment on soil quality for polycyclic aromatic hydrocarbons (PAHs)-contaminated soils. Accumulation of oxygenated-polycyclic aromatic hydrocarbons (oxy-PAHs) was observed, but quantitative measurement on the most abundant compound 9,10-anthraquinone (ATQ) showed lower accumulation of the compound than that reported for ethanol (ET) based Fenton treatment. In general, as compared to conventional water (CW) based Fenton treatment, the EL based Fenton treatment exerted either a lower or higher negative impact on soil physicochemical properties depending on the property type and shared the main disadvantage of reduced soil pH. For revegetation, EL based Fenton treatment was most appropriately adopted for soil with native pH >/~ 6.2 in order to obtain a final soil pH >/~ 4.9 subject to the soil buffering capacity.
Extraction of phenanthrene and fluoranthene from contaminated sand using palm kernel and soybean oils

Von Lau E, Gan S, Ng HK

J Environ Manage, 2012 Sep 30;107:124-30.
PMID: 22595079 DOI: 10.1016/j.jenvman.2012.04.029

Experimental extraction tests are conducted to investigate feasibility of saturated palm kernel oil (PKO) and unsaturated soybean oil (SO) to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sand. The extraction rates and efficiencies for lowly contaminated (LC) and highly contaminated (HC) sands at temperatures of 30 °C and 70 °C are evaluated using empirical first order kinetic dissolution models. In LC sand, the extraction is dominated by the diffusion of PAHs adsorbed onto particle surfaces and the direct dissolution of PAH phase. In HC sand, a rapid diffusion of PAHs adsorbed onto particle surfaces and a direct dissolution of PAH phase occur followed by a slower diffusion of PAHs entrapped within the pores and micropores. Larger diffusion resistance during HC sand extractions results in an average 10.8% reduction in extraction efficiencies compared to LC sand. Increased temperature generally increases the mass transfer rates and extraction efficiencies. Additionally, the physicochemical properties of both oils and PAHs also determine the extent of PAH extraction into oil.
Development and characterisation of novel heterogeneous palm oil mill boiler ash-based catalysts for biodiesel production

Ho WW, Ng HK, Gan S

Bioresour Technol, 2012 Dec;125:158-64.
PMID: 23026328 DOI: 10.1016/j.biortech.2012.08.099

Novel heterogeneous catalysts from calcium oxide (CaO)/calcined calcium carbonate (CaCO(3)) loaded onto different palm oil mill boiler ashes were synthesised and used in the transesterification of crude palm oil (CPO) with methanol to yield biodiesel. Catalyst preparation parameters including the type of ash support, the weight percentage of CaO and calcined CaCO(3) loadings, as well as the calcination temperature of CaCO(3) were optimised. The catalyst prepared by loading of 15 wt% calcined CaCO(3) at a fixed temperature of 800°C on fly ash exhibited a maximum oil conversion of 94.48%. Thermogravimetric analysis (TGA) revealed that the CaCO(3) was transformed into CaO at 770°C and interacted well with the ash support, whereas rich CaO, Al(2)O(3) and SiO(2) were identified in the composition using X-ray diffraction (XRD). The fine morphology size (<5 μm) and high surface area (1.719 m(2)/g) of the fly ash-based catalyst rendered it the highest catalytic activity.
Distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in surface soils from five different locations in Klang Valley, Malaysia

Lau EV, Gan S, Ng HK

Bull Environ Contam Toxicol, 2012 May;88(5):741-6.
PMID: 22297628 DOI: 10.1007/s00128-012-0527-9

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in soil samples were measured at five different sites within Klang Valley, Malaysia. The results showed that the total concentrations of the fourteen priority PAHs ranged from 64 to 155 μg/kg. Irrespective of the land use, all the measured soil PAH concentrations in this study were significantly lower than that found in soil samples in temperate regions. The profile of PAHs in the soils was dominated by the LMW PAHs. The PAHs in Klang Valley soils originated from pyrogenic sources, with a combination of petroleum and biomass combustion in vehicles, industries and non-point sources.
Evaluation of solubility of polycyclic aromatic hydrocarbons in ethyl lactate/water versus ethanol/water mixtures for contaminated soil remediation applications

Yap CL, Gan S, Ng HK

J Environ Sci (China), 2012;24(6):1064-75.
PMID: 23505874

Solubility data of recalcitrant contaminants in cosolvents is essential to determine their potential applications in enhanced soil remediation. The solubilities of phenanthrene, anthracene, fluoranthene and benzo[a]pyrene in ethyl lactate/water and ethanol/water mixtures were measured using equilibrium techniques. The cosolvency powers derived from solubility data were then applied to the model developed from the solvophobic approach to predict the capability of ethyl lactate and ethanol in enhancing the desorption of contaminants from soils. Both ethyl lactate and ethanol cosolvents were shown to be able to enhance the solubilisation of the tested four polycyclic aromatic hydrocarbons by > 4 orders of magnitude above the levels obtained with water alone. However, ethyl lactate demonstrated a greater capacity to enhance PAH solubility than ethanol. The cosolvency powers of ethyl lactate/water system obtained from the end-to-end slope (sigma) and the end-to-half slope (sigma0.5) of the solubilisation curve were 1.0-1.5 and 2.0-2.9 higher than ethanol/water system respectively. In line with this, ethyl lactate/water was demonstrated to enhance the desorption of contaminants from soil by 20%-37% and 18%-61% higher compared to ethanol/water system in low organic content and high organic content soils respectively, with a 2:1 (V/W) ratio of solution:soil and with cosolvent fraction as low as 0.4. With the exception of benzo[a]pyrene, the experimental desorption results agreed fairly with the predicted values, under an applied solution:soil ratio that was enough to hold the capacity of released contaminants.
HPLC method development and validation for simultaneous detection of Arabinoside-C and doxorubicin

Mistiran AF, Dzarr AA, Gan SH

Toxicol. Mech. Methods, 2010 Oct;20(8):472-81.
PMID: 20626302 DOI: 10.3109/15376516.2010.503246

This paper describes a new validated high performance liquid chromatography (HPLC) method for the simultaneous determination of two anti-cancer drugs, Arabinoside-C (Ara-C) and doxorubicin hydrochloride (DOX). A simultaneous determination method saves cost and time as both drugs can be injected into a single HPLC system without the need to change or re-equilibrate with a new mobile phase. The objective of the study is to develop a simultaneous determination method of two anti-cancer drugs, Ara-C and DOX. The mobile phase consisted of a mixture (45:55) of acetonitrile:ammonium hydrogen phosphate aqueous solution (0.01 M) at pH 6.2 at a flow rate of 0.3 ml/min, with UV detection at 252 nm. Separation was achieved on a C-18 column (5 µm: 250 mm × 4.6 mm) maintained at 30°C in a column oven. The method was linear between 325 ng/ml and 10 µg/ml for Ara-C and 625 ng/ml and 20 µg/ml for DOX. The limit of detection (LOD) was 20 ng/ml for Ara-C and 60 ng/ml for DOX. The developed HPLC method achieved good precision and accuracy as well as limit of quantitations. The developed and validated method is suitable to be used for routine analysis of Ara-C and DOX.
Fenton based remediation of polycyclic aromatic hydrocarbons-contaminated soils

Yap CL, Gan S, Ng HK

Chemosphere, 2011 Jun;83(11):1414-30.
PMID: 21316731 DOI: 10.1016/j.chemosphere.2011.01.026

This paper aims to review the applications of Fenton based treatments specifically for polycyclic aromatic hydrocarbons-contaminated soils. An overview of the background and principles of Fenton treatment catalysed by both homogenous (conventional and modified Fenton) and heterogeneous (Fenton-like) catalysts is firstly presented. Laboratory and field soil remediation studies are then discussed in terms of efficiency, kinetics and associated factors. Four main scopes of integrated Fenton treatments, i.e. physical-Fenton, biological-Fenton, electro-Fenton and photo-Fenton are also reviewed in this paper. For each of these integrated remediation technologies, the theoretical background and mechanisms are detailed alongside with achievable removal efficiencies for polycyclic aromatic hydrocarbons in contaminated soils compared to sole Fenton treatment. Finally, the environmental impacts of Fenton based soil treatments are documented and discussed.
Hyperthermic effects of Durio zibethinus and its interaction with paracetamol

Chua YA, Nurhaslina H, Gan SH

Methods Find Exp Clin Pharmacol, 2008 Dec;30(10):739-43.
PMID: 19271022 DOI: 10.1358/mf.2008.30.10.1316830

Because durian (Durio zibethinus), which is known in Southeast Asia as "the king of fruits", is thought to have special body-warming properties, it should not be consumed with paracetamol due to a risk of toxic effects. The claim of warming properties, however, has not been scientifically proven. This study was conducted to investigate durian's hyperthermic effect and its toxicity when consumed together with paracetamol in rats. Five groups of rats (n=6) were fed with: 1) distilled water (4 ml/250 g), 2) homogenized durian (4 g/250 g), 3) paracetamol solution (2400 mg/kg), 4) durian (4 g/250 g) followed by paracetamol solution (2400 mg/kg), or 5) prazosin solution (15 mg/kg, pregavaged) followed 1 h later by durian (4 g/250 g) and paracetamol solution (2400 mg/kg). Rectal temperature, systolic blood pressure and serum alanine aminotransferase (ALT) levels were taken from each rat at baseline and after the various administrations at 1, 2 and 5 h. Our results showed that the body temperature of rats in the durian-treated group was not significantly elevated when compared to the control. However, there was a significant decrease in body temperature over time in animals from groups 4 and 5. We did not, however, observe a consistent pattern of blood pressure change. Serum chemical analysis for ALT also did not show any significant change in any of the groups. In conclusion, contrary to what some believe, even though durian was found to increase body temperature in some rats, this increment was not significant. Rats receiving the durian-paracetamol combination showed a significant drop in body temperature, which may explain the belief that the two mixtures are toxic. However, the exact mechanism of toxicity is still unknown.
Application of vegetable oils in the treatment of polycyclic aromatic hydrocarbons-contaminated soils

Yap CL, Gan S, Ng HK

J Hazard Mater, 2010 May 15;177(1-3):28-41.
PMID: 20006435 DOI: 10.1016/j.jhazmat.2009.11.078

A brief review is conducted on the application of vegetable oils in the treatment of PAH-contaminated soils. Three main scopes of treatment strategies are discussed in this work including soil washing by oil, integrated oil-biological treatment and integrated oil-non-biological treatment. For each of these, the arguments supporting vegetable oil application, the applied treatment techniques and their efficiencies, associated factors, as well as the feasibility of the techniques are detailed. Additionally, oil regeneration, the environmental impacts of oil residues in soil and comparison with other commonly employed techniques are also discussed.
Remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs)

Gan S, Lau EV, Ng HK

J Hazard Mater, 2009 Dec 30;172(2-3):532-49.
PMID: 19700241 DOI: 10.1016/j.jhazmat.2009.07.118

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic micropollutants which are resistant to environmental degradation due to their highly hydrophobic nature. Concerns over their adverse health effects have resulted in extensive studies on the remediation of soils contaminated with PAHs. This paper aims to provide a review of the remediation technologies specifically for PAH-contaminated soils. The technologies discussed here include solvent extraction, bioremediation, phytoremediation, chemical oxidation, photocatalytic degradation, electrokinetic remediation, thermal treatment and integrated remediation technologies. For each of these, the theories are discussed in conjunction with comparative evaluation of studies reported in the specialised literature.
Fine needle aspiration cytology of the thyroid--a review of experience in 1853 cases

Jayaram G, Razak A, Gan SK, Alhady SF

Malays J Pathol, 1999 Jun;21(1):17-27.
PMID: 10879275

1853 thyroid lesions subjected to cytological sampling (either by the fine needle aspiration or fine needle capillary sampling technique) from January 1992 to December 1997 at the University Hospital, Kuala Lumpur, were reviewed. Nodular goitre was the most common thyroid lesion needled (67.35%). Among the neoplastic lesions, follicular neoplasms predominated (64%), followed by papillary carcinoma (29.4%). In 325 cases, partial or total thyroidectomy had been done, providing material for histological review and cyto-histological correlation. Cytological diagnosis was found to have high sensitivity and specificity rates of over 75%. Besides, most non-neoplastic thyroid lesions could be diagnosed on cytology. The scope of cytology in the diagnosis of lymphomas, anaplastic and metastatic tumours rendered diagnostic biopsies (or thyroidectomy) unnecessary in these cases. Being a cost-effective technique and having the capacity to provide exact morphological diagnosis in a large variety of thyroid lesions, cytology is obviously the method of choice in the assessment of thyroid nodules.

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