Displaying publications 1 - 20 of 44 in total

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  1. Sharma S, Mohamad NA, Monga D, Achana S
    Med J Malaysia, 1996 Dec;51(4):453-6.
    PMID: 10968033
    Three hundred and five primigravid women were interviewed at term to assess the acceptability of epidural during labour, and reasons for the decisions. Data was collected on a prestructured proforma which consisted of background information, socio-economic status, knowledge about epidural analgesia, source of information and reasons for choice. Of the 305 patients only 17.3% were willing to receive epidural analgesia. This group consisted of 56.6% non-Malay women. Those employed in professional or skilled jobs (56.6%) also readily consented for epidural. Nearly half the women willing for epidural had received college (tertiary) education (43.3%) and more than a quarter (26.4%) were over 30 years of age. The majority of those who were unwilling had no prior knowledge about the procedure, and refused either out of fear, ignorance, resistance from husbands, on religious grounds or following poor feedback from friends. In order to advocate epidural analgesia, knowledge has to be targeted to the relatively less educated, unemployed women, mainly through the media or personally in the antenatal clinic by doctors and nurses. Services have to be improved as substandard analgesia may send out wrong messages and actually do more harm than good.
  2. Noor Mohamad NA, Omar J
    J Obstet Gynaecol Res, 2024 Jul 19.
    PMID: 39030916 DOI: 10.1111/jog.16031
    Cervical cancer is preventable due to effective screening to detect pre-malignant lesion, and vaccination against its causative organism namely human papillomavirus (HPV). This review article described current situation of cervical cancer in Malaysia. There is decreasing cervical cancer incidence in the country, with age-standardized rate of 10.3, versus 14.1 and 7.5 per 100 000 for worldwide and high-income countries, respectively. School-based HPV vaccination is part of national immunization since 2010, with yearly coverage rate of 83%-91%. The figure declined during coronavirus disease-19 pandemic due to scarce vaccine supply and movement-control order, resulting in about 500 000 students missing their course, with catch-up program currently onboard. Opportunistic cervical screening program started in 1960s with cervical smear cytology, which is succeeded by HPV DNA screening since 2020. Cervical cytology remains indispensable  screening method in healthcare facility without access to HPV test kit, and used to triage high-risk HPV positive with abnormal cytology that require urgent colposcopy. Computed tomography is the main imaging modality to assess local and distal extent of cervical cancer. Primary surgical treatment for early-stage cancer is performed by trained gynecologic oncologist, with long waiting list for radiation therapy in locally advanced disease due to limited available public facility. There is restricted access to targeted therapy due to high treatment cost. In conclusion, Malaysia is heading toward cervical cancer elimination through rigorous investment in primary and secondary prevention, and increase in public engagement with the support of government policy enforcement.
  3. Seong Tan PC, Nik Mohamad NA, Gan SH
    Pain Manag Nurs, 2013 Jun;14(2):102-9.
    PMID: 23688364 DOI: 10.1016/j.pmn.2010.12.004
    The association between pain intensity and its control by intravenous patient-controlled analgesia (IV-PCA) with fentanyl after a laparotomy for cystectomy/salphingoophorectomy, myomectomy, or hysterectomy was investigated. IV fentanyl infusion was administered to patients (n = 94) at 3 μg/kg/h to provide intraoperative analgesia after induction of general anesthesia. Postoperative fentanyl requirements were quantified via IV-PCA, and the amounts of rescue fentanyl required both during and after surgery were recorded. Mean values for PCA use as well as the visual analog scores (VAS) for pain were documented for up to 24 hours. The association between postoperative fentanyl requirements and VAS were then analyzed by using Mann-Whitney or Kruskal-Wallis tests. Patients with lower midline incisions had greater degrees of pain (p < .05) during the first 16 hours after surgery but did not consume more fentanyl compared with patients with Pfannenstiel incisions. Subjects who underwent operations lasting >4 hours required more rescue fentanyl during surgery (p < .05). However, this group consumed less fentanyl during the first 4 hours after surgery (p < .05). The demand at the fourth 4-hour period was lower among subjects undergoing myomectomy compared with cystectomy/salphingoophorectomy or hysterectomy (p = .045). Only a poor correlation was observed between pain intensity and analgesic usage. Postoperative pain intensity is influenced by the type of surgical incision but not the type of gynecologic surgery nor the duration of surgery. The relationship between subjective pain ratings with analgesic consumption is weak. Prolonged intraoperative administration of continuous IV fentanyl infusion may reduce fentanyl requirements in the immediate postoperative period.
  4. Khoo YT, Halim AS, Singh KK, Mohamad NA
    PMID: 20815896 DOI: 10.1186/1472-6882-10-48
    Full-thickness burn wounds require excision and skin grafting. Multiple surgical procedures are inevitable in managing moderate to severe full-thickness burns. Wound bed preparations prior to surgery are necessary in order to prevent wound infection and promote wound healing. Honey can be used to treat burn wounds. However, not all the honey is the same. This study aims to evaluate the wound contraction and antibacterial properties of locally-produced Tualang honey on managing full-thickness burn wounds in vivo.
  5. Tan PC, Hassan SK, Mohamad NA, Gan SH
    J Clin Pharm Ther, 2012 Feb;37(1):100-4.
    PMID: 21128989 DOI: 10.1111/j.1365-2710.2010.01232.x
    WHAT IS KNOWN AND OBJECTIVE: Interindividual variability in drug responses may be attributable to genetically determined alteration in enzyme activity. In this study, we investigated the association between cytochrome P450 3A4 (CYP3A4) genetic polymorphisms and post-operative fentanyl requirements.

    METHODS: Patients (n = 94) scheduled for gynaecological laparotomy received i.v. fentanyl infusion (3 μg/kg/h) after induction of general anaesthesia. Post-operative fentanyl requirements were quantified by using a patient-controlled analgesia and the number of i.v. fentanyl rescue analgesia required were recorded. Pain control was assessed using visual analogue scores (VAS) and fentanyl's adverse effects were documented. CYP3A4*4, CYP3A4*5 and CYP3A4*18 alleles of cytochrome P450 3A4 were identified by polymerase chain reaction-restriction fragment length polymorphism. Differences in fentanyl requirements, VAS scores and adverse effects among the various genotypes were compared.

    RESULTS AND DISCUSSION: No CYP3A4*4 and CYP3A4*5 alleles were detected. Eighty-nine patients (94·7%) were wild-type, five (5·3%) were heterozygous and none was homozygous. No significant difference was demonstrated between the genotype groups in terms of fentanyl consumption, pain control and adverse effects.

    WHAT IS NEW AND CONCLUSION: CYP3A4*4 and CYP3A4*5 are rare in the Malaysian Malay population. Genetic polymorphism of CYP3A4*18 may not play an important role in influencing postoperative fentanyl requirements.

  6. Mohamad NA, Mustafa S, Khairil Mokhtar NF, El Sheikha AF
    J Sci Food Agric, 2018 Sep;98(12):4570-4577.
    PMID: 29505123 DOI: 10.1002/jsfa.8985
    BACKGROUND: The pharmaceutical industry has boosted gelatin consumption worldwide. This is supported by the availability of cost-effective gelatin production from porcine by-products. However, cross-contamination of gelatin materials, where porcine gelatin was unintentionally included in the other animal sources of gelatin, has caused significant concerns about halal authenticity. The real-time polymerase chain reaction (PCR) has enabled a highly specific and sensitive animal species detection method in various food products. Hence, such a technique was employed in the present study to detect and quantify porcine DNA in gelatin using a molecular beacon probe, with differences in performance between mitochondrial (cytochrome b gene) and chromosomal DNA-(MPRE42 repetitive element) based porcine-specific PCR assays being compared.

    RESULTS: A higher sensitivity was observed in chromosomal DNA (MPRE-PCR assay), where this assay allows the detection of gelatin DNA at amounts as as low as 1 pg, whereas mitochondrial DNA (CBH-PCR assay) can only detect at levels down to 10 pg of gelatin DNA. When an analysis with commercial gelatin and gelatin capsule samples was conducted, the same result was observed, with a significantly more sensitive detection being provided by the repetitive element of chromosomal DNA.

    CONCLUSION: The present study has established highly sensitive DNA-based porcine detection systems derived from chromosomal DNA that are feasible for highly processed products such as gelatin and gelatin capsules containing a minute amount of DNA. This sensitive detection method can also be implemented to assist the halal authentication process of various food products available on the market. © 2018 Society of Chemical Industry.

  7. Mohamad NA, Rahman AA, Sheikh Abdul Kadir SH
    Oncol Lett, 2023 Jan;25(1):34.
    PMID: 36589673 DOI: 10.3892/ol.2022.13620
    Piper betle leaves are widely cultivated in Malaysia, India, Indonesia and Thailand. They have been used as a traditional medicine for centuries due to their medicinal properties, including antioxidant, antiproliferative, antibacterial, antifungal and anti-inflammatory properties, which are attributable to their high phenolic contents. Hydroxychavicol (HC), a primary constituent of P. betle leaves, is known to possess antiproliferative activity at micromolar doses on various cancer cell lines of different origins while leaving normal cells unharmed. The present review summarises the mechanisms of action of HC reported in the literature, reviews the scope of work done thus far and outlines the direction of future research on the potential of HC as an anticancer agent. PubMed, Scopus and Web of Science were searched using the keywords (hydroxychavicol OR 4-allylpyrocatechol OR 4-allylcatechol) AND (cancer OR carcinogenesis OR tumour OR carcinoma) to acquire research articles. In vitro studies reported several possible mechanisms for the chemopreventive effects of HC against cancer cell lines, including chronic myelogenous leukaemia (CML), prostate, glioma, breast and colorectal cancers, while in vivo studies encompassed investigations on Ehrlich ascites carcinoma cells in Swiss albino mice and a CML mouse model. These studies suggest that HC exerts its anticancer effect via the modulation of mitochondrial membrane potential and the c-Jun N-terminal kinase, mitogen-activated protein kinase and endoplasmic reticulum-unfolded protein responses pathways and the generation of reactive oxygen species. In summary, future research should focus on combinations of HC with other anticancer drugs and testing in animal models to evaluate its bioavailability, potency and tissue and dose selectivity.
  8. Mariappan V, Vellasamy KM, Mohamad NA, Subramaniam S, Vadivelu J
    Front Microbiol, 2021;12:718774.
    PMID: 34759896 DOI: 10.3389/fmicb.2021.718774
    On a global scale, antimicrobial resistance (AMR) is recognized as a One Health challenge due to the continual and increased development and distribution of resistant microbes and genes among humans, animals, and the environment. These sectors contribute to the increase in AMR, as antibiotics are widely used in healthcare to treat or prevent bacterial infection; as growth enhancers, therapeutics and metaphylactics in animal husbandry; and transmitted in the environment through irrigation using wastewater or inappropriate disposal and treatment of human and agricultural waste. However, there is a major drawback in terms of the lack of research assessing the coexistence of AMR in these sectors. Extensive research highlighted food-animal manufacture structures that are likely to harbor reservoirs or promote transmission of AMR, in addition to increasing human colonization with AMR commensal bacteria. Numerous antibiotic stewardship policies have been designed and implemented in medical practices and animal husbandry in high- and middle-income countries. However, research concentrating on high-income settings, attitudes, emotions, and beliefs on the utilization of antimicrobials remain underexplored in lower- and middle-income countries such as Malaysia. Microbiological, epidemiological, and social science exploration are required at community and farming across the One Health range to fill huge gaps in information and knowledge of AMR. Manipulating human activities and character associated with antibiotics is a multifaceted progression that includes elements like knowledge, social behavior, attitudes, approaches, social standards, socioeconomic settings, peer pressure, experiences, and biophysical environment. Therefore, understanding these aspects in the utilization of antimicrobial drugs among the different sectors is essential to develop and implement policies to curb AMR development and transmission that overarch all sectors within the One Health consortium in Malaysia.
  9. Mohamad NA, Al-Emerieen AF, Irekeola AA, Shueb RH
    Malays J Med Sci, 2024 Jun;31(3):32-51.
    PMID: 38984254 DOI: 10.21315/mjms2024.31.3.3
    Antibiotics are widely used to treat bacterial infections. The effectiveness of antibiotics is very important, but unfortunately, prolonged exposure leads to the development of antibiotic resistance in some bacteria. Hence, using natural products as antibacterial agents is an attractive alternative, given that they have been used as traditional medicine since the existence of humanity. This study systematically reviewed the antibacterial activity of Malaysian bee products such as honey, propolis and bee bread. Five electronic databases: i) PubMed; ii) ScienceDirect; iii) Scopus; iv) Web of Science Core Collection and v) Google Scholar, were searched for relevant articles. A total of 153 articles were obtained from the initial search. Of these, 32 articles, including 24 on honey, eight on propolis and one on bee bread, were selected based on inclusion and exclusion criteria. Most studies reported that honey, propolis and bee bread demonstrated antibacterial properties against Gram-positive and Gram-negative bacteria.
  10. Vasudevan R, Ismail P, Jaafar N, Mohamad N, Etemad E, Wan Aliaa W, et al.
    Balkan J Med Genet, 2014 Jun;17(1):37-40.
    PMID: 25741213 DOI: 10.2478/bjmg-2014-0023
    The aim of this study was to determine the association of the c.894G>T; p.Glu298Asp polymorphism and the variable number tandem repeat (VNTR) polymorphism of the endothelial nitric oxide synthase (eNOS) gene and c.181C>T polymorphism of the bradykinin type 2 receptor gene (B2R) in Malaysian end-stage renal disease (ESRD) subjects. A total of 150 ESRD patients were recruited from the National Kidney Foundation's (NKF)dialysis centers in Malaysia and compared with 150 normal healthy individuals. Genomic DNA was extracted from buccal cells of all the subjects. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was carried out to amplify the products and the restricted fragments were separated by agarose gel electrophoresis. Statistical analyses were carried out using software where a level of p <0.05 was considered to be statistically significant. The genotypic and allelic frequencies of the B2R gene (c.181C>T, 4b/a) and eNOS gene (c.894G>T) polymorphisms were not statistically significant (p >0.05) when compared to the control subjects. The B2R and eNOS gene polymorphisms may not be considered as genetic susceptibility markers for Malaysian ESRD subjects.
  11. Katherason SG, Naing L, Jaalam K, Nik Mohamad NA, Bhojwani K, Harussani ND, et al.
    J Infect Dev Ctries, 2010 Mar 08;4(2):118-23.
    PMID: 20212345
    BACKGROUND: Hand decontamination is a critical infection control practice in the prevention of nosocomial infection. This study was conducted to observe the hand hygiene practices of nurses and doctors in two intensive care units (ICUs) in Malaysia.

    METHODOLOGY: Staff members were observed during patient contacts, and their hand washing techniques and hand hygiene practices were monitored. Five contact periods were observed for staff members while they cared for their assigned patients. Hand hygiene practices before and after patient contacts were categorized as clean uncontaminated, clean recontaminated, new gloves, and unchanged contaminated gloves. Compliance to hand-washing steps and time taken for hand washing were analyzed. Appropriate use of gloves based on CDC criteria also was assessed.

    RESULTS: Compliance to hand hygiene practices was 70% before each patient contact. Staff members did not completely adhere to the hand-washing steps. The average time taken to wash hands was 20 seconds, and the necessary steps (rubbing palm over dorsum; rubbing fingers interlaced, and rotational rubbing of thumbs) were practiced minimally by all staff. Hand washing protocol was generally followed by all staff (100%). Alcohol hand rubs were available but were used moderately (60%); when used, staff members did not wait for the alcohol to dry. Only 4% of staff changed contaminated gloves between patients.

    CONCLUSIONS: Hand hygiene compliance by ICU staff members needs to be improved. Improving adherence to correct hand hygiene techniques will require effective education programs and behavioral modification techniques. Moreover, hand hygiene guidelines must be incorporated into new staff orientation programs and the continuing education curriculum in the two hospitals studied.

  12. Mohamad NA, Mustafa S, El Sheikha AF, Khairil Mokhtar NF, Ismail A, Ali ME
    J Sci Food Agric, 2016 May;96(7):2344-51.
    PMID: 26441285 DOI: 10.1002/jsfa.7482
    Poor quality and quantity of DNA extracted from gelatin and gelatin capsules often causes failure in the determination of animal species using PCR. Gelatin, which is mainly derived from porcine and bovine, has been a matter of concern among customers in order to fulfill religious obligation and safety precaution against several transmissible infectious diseases associated with bovine species. Thus, optimised DNA extraction from gelatin is very important for successful real-time PCR detection of gelatin species. In this work, the DNA extraction method was optimised in terms of lysis incubation period and inclusion of pre-treatment pH modification of samples.
  13. Abu Bakar K, Mohamad NA, Hodi Z, McCulloch T, Williams A, Christian M, et al.
    Pediatr Nephrol, 2019 12;34(12):2557-2562.
    PMID: 31520127 DOI: 10.1007/s00467-019-04346-z
    BACKGROUND: Late acute cellular rejection (LACR) is associated with poorer graft outcomes and non-adherence. Non-adherence to tacrolimus can be indirectly assessed by the intra-patient variability (IPV) of tacrolimus trough levels. The threshold of IPV associated with rejection is not known.

    METHODS: We conducted a case-control study comparing 25 patients with biopsy-proven LACR against 25 stable controls matched for age group, primary diagnosis and time post-transplant. IPV was calculated using coefficient of variance (CV) and mean absolute deviation (MAD) using tacrolimus levels in the preceding 12 months. We also assessed the percentage time for tacrolimus levels

  14. Mohamad NA, Azis N, Jasni J, Kadir MZAA, Yunus R, Yaakub Z
    Nanomaterials (Basel), 2021 Mar 19;11(3).
    PMID: 33808641 DOI: 10.3390/nano11030786
    This experimental study aims to examine the partial discharge (PD) properties of palm oil and coconut oil (CO) based aluminum oxide (Al2O3) nanofluids with and without surfactants. The type of surfactant used in this study was sodium dodecyl sulfate (SDS). The volume concentrations range of Al2O3 dispersed in oil samples was varied from 0.001% to 0.05%. The ratio of surfactants to nanoparticles was set to 1:2. In total, two different types of refined, bleached and deodorized palm oil (RBDPO) and one type of CO were measured for PD. Mineral oil (MO) was also examined for comparison purpose. PDIV measurements for all samples were carried out based on rising voltage method whereby a needle-sphere electrode configuration with a gap distance of 50 mm was chosen in this study. Al2O3 improves the PDIVs of RBDPO, CO and MO whereby the highest improvements of PDIVs are 34%, 39.3% and 27%. The PD amplitude and repetition rate of RBDPO improve by 38% and 81% while for CO, it can increase up to 65% and 80% respectively. The improvement of PD amplitude and repetition rate for MO are 18% and 95%, regardless with and without SDS. Without SDS, the presence of Al2O3 could cause 26%, 75% and 65% reductions of the average emission of light signals for RBDPOA, RBDPOB and CO with the improvement of PD characteristics but both events do not correlate at the same volume concentration of Al2O3. On the other hand, the average emission of light signal levels of the oils increases with the introduction of SDS. The emission of light signal in MO does not correlate with the PD characteristics improvement either with or without SDS.
  15. Mohamad NA, Azis N, Jasni J, Ab Kadir MZA, Yunus R, Yaakub Z
    Materials (Basel), 2018 Mar 30;11(4).
    PMID: 29601520 DOI: 10.3390/ma11040532
    This paper presents a sealed ageing study of palm oil (PO) and coconut oil (CO) in the presence of insulation paper. The type of PO under study is refined, bleached, and deodorized palm oil (RBDPO) olein. Three different variations of RBDPO and one sample of CO are aged at temperatures of 90 °C, 110 °C, and 130 °C. The properties of RBDPO and CO as well as paper under ageing are then analysed through dielectric and physicochemical measurements. It is found that the effect of ageing is not significant on the alternating current (AC) breakdown voltages and relative permittivities of RBDPO and CO. There is a slight increment trend of the resistivity for CO, while for all of the RBDPO, the resistivity slightly decreases as the ageing progresses. Only CO shows an apparent reduction of the dielectric dissipation factor. Throughout the ageing time, the acidities of all of the RBDPO and CO remain at low level, while the moisture in oils decreases. The tensile index (TI) of the papers for all of the RBDPO and CO retain more than 50% of the TI. A significant increment of the paper ageing rates of all of the RBDPO and CO is observed at an ageing temperature of 130 °C.
  16. Komaruddin SA, Mohamad NA, Fatihah-Syafiq M, Badli Sham BH, Mamat MA, Zakaria N
    Data Brief, 2020 Feb;28:104994.
    PMID: 32226800 DOI: 10.1016/j.dib.2019.104994
    This data article is about reptiles (lizard, snake, and skink) captured from fragmented forest within man-made lake of Tasik Kenyir that is situated in Terengganu State, Peninsular Malaysia. Data collection was conducted in January 2019 and sampling methods included drift fenced-pitfall traps and Visual Encounter Survey (VES). All animals were identified, measured snout to vent (SVL) and weighted before their release at the site of capture. The highlights like conservation statuses in the wild, detection type and substrate type are presented with the data to increase its value. A total of 73 individuals from 18 species, 15 generas and seven families of reptiles were recorded. The data comprised of seven reptile family groups Agamidae, Gekkonidae, Scincidae, Colubridae, Elapidae, Viperidae and Homalopsidae. Reptiles like Cyrtodactylus quadrivirgattus (n = 33, 45.2%) and Aphaniotis fusca (n = 7, 9.6%) were most dominant in the checklist and most of the animals were captured using VES. Data of SVL and mass of the animals can be further interpreted by researchers to assess the health condition of animals in the altered habitats.
  17. Hamzah N, Mohamad NA, Thiruselvam I, Hariri F, Veeramuthu V, Mazlan M, et al.
    Appl Neuropsychol Adult, 2019 08 21;28(4):416-426.
    PMID: 31431094 DOI: 10.1080/23279095.2019.1648264
    This study assessed the validity (construct validity) and reliability (internal consistency) of the Neuropsychological Assessment Battery Screening Module (S-NAB) in detecting mild cognitive deficit/alteration in multicultural, multilingual, and multiethnic mild traumatic brain injury (mTBI) population of Malaysia. S-NAB and Montreal Cognitive Assessment (MoCA) data from 114 patients with mTBI (93 males; 21 females) aged 18 to 60 years old were obtained at University Malaya Medical Center, Malaysia. The mean age was 28.17 ± 8.57 years and mean education years was 12.40 ± 2.01. Convergent validity was assessed between S-NAB domain scores and MoCA total scores by using Pearson's correlation and internal consistency was assessed using Cronbach's alpha. Acceptable internal consistency (α ≥ .70) was found for Attention, Language, and Memory domains but weak internal consistencies (α 
  18. Ansari N, Ramachandran V, Mohamad NA, Salim E, Ismail P, Hazmi M, et al.
    Glob Med Genet, 2023 Jan;10(1):12-18.
    PMID: 36703777 DOI: 10.1055/s-0042-1760384
    Background  Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder, and the underlying causes remain unknown and have not been fully elucidated. Several candidate genes have been associated with T2DM in various populations with conflicting results. The variations found in glucokinase ( GCK ), glucokinase regulatory protein ( GCKR ), and glucose-6-phosphatase 2 ( G6PC2 ) genes were not well studied, particularly among Asians. Aims  The main objective of this study was to determine the candidate genetic polymorphisms of GCK (rs1799884), GCKR (rs780094), and G6PC2 (rs560887) genes in T2DM among Malay ethnics. Methods  In this candidate gene association study, a total of 180 T2DM subjects and 180 control subjects were recruited to determine the genotypes using polymerase chain reaction-restriction fragment length polymorphism and Taqman probe assay methods. Genotype and allele frequencies in case and control samples were compared using the chi-squared test to determine a significant difference. Results  The body mass index, fasting blood glucose, hemoglobin A1c, systolic and diastolic blood pressure, and total cholesterol were significantly different ( p  
  19. Mohamad NA, Nasef MM, Abdullah TAT, Ahmad A, Ting TM
    Environ Sci Pollut Res Int, 2023 Nov;30(55):116906-116920.
    PMID: 37121947 DOI: 10.1007/s11356-023-26913-6
    A series of fibrous aminated adsorbents for CO2 adsorption were prepared by covalent incorporation of poly (glycidyl methacrylate) (PGMA) by graft copolymerization of GMA onto electron beam (EB) irradiated polyethylenepolypropylene (PE/PP) fibrous sheets and subsequent amination with ethylenediamine (EDA), diethylenetriamine (DETA), or tetraethylenepentamine (TEPA). The physico-chemical properties of the adsorbents were evaluated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric (TGA), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. All the adsorbents displayed typic primary and secondary amine features combined with a decrease in both of crystallinity and surface area of PE/PP, and such a decrease was higher in adsorbents with longer aliphatic chain of the amine. Of all adsorbents, TEPA-containing fibres showed the highest CO2 adsorption capacity and thus was further investigated for CO2 capture from CO2/CH4 mixtures of different gas ratios under various pressures and temperatures. The selectivity of CO2 over CH4 and equilibrium isotherms, kinetics, and thermodynamics of the adsorption on the fibrous aminated adsorbent were all investigated. The Sips model was found to best fit the isotherm of CO2 adsorption suggesting the presence of a combination of monolayer and multilayer adsorptions. The adsorption kinetic data was found to best fit Elovich model reflecting chemisorption. The ΔG°, ΔS°, and ΔH° showed positive values suggesting that the adsorption of CO2 on the present fibrous adsorbent was non-spontaneous with an increase in randomness implying that the process was endothermic. Overall, it can be suggested that PE/PP-g-PGMA/TEPA adsorbent has a strong potential for separation of CO2 from NG.
  20. Mohamad NA, Azis N, Jasni J, Ab Kadir MZA, Yunus R, Yaakub Z
    Nanotechnology, 2020 Aug 04;31(42):425708.
    PMID: 32748802 DOI: 10.1088/1361-6528/aba1b9
    In this paper, the effect of different types of surfactants on the lightning breakdown voltages of palm oil (PO) and coconut oil (CO) based aluminium oxide (Al2O3) nanofluids is investigated. Three different types of surfactants were used in this study known as cationic (cetyl trimethyl ammonium bromide (CTAB)), anionic (sodium dodecyl sulfate (SDS)) and non-ionic (oleic acid (OA)). The volume percentage concentrations of Al2O3 dispersed into PO and CO were varied from 0.001% to 0.05%. The ratio of surfactant to the nanoparticles was set to 50% from the volume concentration of nanoparticles which equivalent to 1:2. In total, two types of refined, bleached and deodorized palm oil (RBDPO) and one type of CO were examined for lightning breakdown voltage. The test was carried out based on needle-sphere electrodes configuration with 25 mm gap distance. The presence of Al2O3 improves both positive and negative lightning breakdown voltages of RBDPO and CO. Under the positive and negative polarities, the CTAB does provide further improvements on the lightning breakdown voltages of RBDPOA (1st type of samples) and CO at most of the volume of concentration of Al2O3. SDS and OA could also further improve the lightning breakdown voltage of CO at certain volume concentration of Al2O3. On the other hand, the lightning breakdown voltage of RBDPOB based Al2O3 nanofluid (2nd type of samples) does not further improve with the introduction of surfactants. At most of the volume concentration of Al2O3, the introduction of CTAB further increases the times to breakdown and decrease the average streamer velocities of RBDPOA under both polarities. The same finding is observed for CO under positive polarity with CTAB and SDS as well as under negative polarity in the presence of all surfactants. The streamer velocities and times to breakdown patterns of RBDPOB based Al2O3 nanofluid are inconsistent in the presence of all surfactants. It is found that RBDPO and CO based Al2O3 nanofluids have second mode of streamer whereby the streamer velocities are from 1 km s-1 to 1.63 km s-1 regardless with or without surfactants.
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