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The inhibitory effects of Gelam honey and its extracts on nitric oxide and prostaglandin E(2) in inflammatory tissues

Kassim M, Achoui M, Mansor M, Yusoff KM

Fitoterapia, 2010 Dec;81(8):1196-201.
PMID: 20708657 DOI: 10.1016/j.fitote.2010.07.024

We investigated the effects of honey and its methanol and ethyl acetate extracts on inflammation in animal models. Rats' paws were induced with carrageenan in the non-immune inflammatory and nociceptive model, and lipopolysaccharide (LPS) in the immune inflammatory model. Honey and its extracts were able to inhibit edema and pain in inflammatory tissues as well as showing potent inhibitory activities against NO and PGE(2) in both models. The decrease in edema and pain correlates with the inhibition of NO and PGE(2). Phenolic compounds have been implicated in the inhibitory activities. Honey is potentially useful in the treatment of inflammatory conditions.
Fulltext Circumstances surrounding accidental poisoning in children

Azizi BH, Zulkifli HI, Kassim MS

Med J Malaysia, 1994 Jun;49(2):132-7.
PMID: 8090091

Circumstances surrounding accidental ingestion of poisons were investigated in families of 70 hospitalised children. Indian children were more likely to be hospitalised for poisoning. Poor safety measures directly contributed to poisoning incidents. Poisons had not been stored safely and only in 12.9 per cent of families were the poisons allegedly kept in cupboards. Kerosene had been ingested from soft drink containers in 70 per cent of instances. Medications had been taken mainly from plastic envelopes (57.9%) or bottles (31.6%). Safety practices in the homes of cases and 140 controls were compared. As a whole parents of victims had poor safety practices when compared with parents of controls. Poisoning incidents were discovered by mothers in 75.0 per cent of the cases. Vomiting was induced by parents in 32.3 per cent of cases involving medications and non-volatile items, and in 41.6 per cent of kerosene ingestions. Before hospitalisation 59.4 per cent were brought to general practitioners and 22.7 per cent to government clinics. Mothers were the main attendants when children were brought for medical care. This study highlights the need for measures to prevent childhood poisoning and reduce its morbidity. Household products and medications should be made safer to children through improved packaging, prescribing instructions and education. Safety and first aid education may be directed towards parents, particularly mothers, through the media and health facilities.
Mosquito-borne haemorrhagic fever

George R, Kassim MS, Wah LT

Med J Malaysia, 1974 Sep;29(1):11-6.
PMID: 4282623
Fulltext Gelam honey has a protective effect against lipopolysaccharide (LPS)-induced organ failure

Kassim M, Mansor M, Al-Abd N, Yusoff KM

Int J Mol Sci, 2012;13(5):6370-81.
PMID: 22754370 DOI: 10.3390/ijms13056370

Gelam honey exerts anti-inflammatory and antioxidant activities and is thought to have potent effects in reducing infections and healing wounds. The aim of this study was to investigate the effects of intravenously-injected Gelam honey in protecting organs from lethal doses of lipopolysaccharide (LPS). Six groups of rabbits (N = 6) were used in this study. Two groups acted as controls and received only saline and no LPS injections. For the test groups, 1 mL honey (500 mg/kg in saline) was intravenously injected into two groups (treated), while saline (1 mL) was injected into the other two groups (untreated); after 1 h, all four test groups were intravenously-injected with LPS (0.5 mg/kg). Eight hours after the LPS injection, blood and organs were collected from three groups (one from each treatment stream) and blood parameters were measured and biochemical tests, histopathology, and myeloperoxidase assessment were performed. For survival rate tests, rabbits from the remaining three groups were monitored over a 2-week period. Treatment with honey showed protective effects on organs through the improvement of organ blood parameters, reduced infiltration of neutrophils, and decreased myeloperoxidase activity. Honey-treated rabbits also showed reduced mortality after LPS injection compared with untreated rabbits. Honey may have a therapeutic effect in protecting organs during inflammatory diseases.
Fulltext Gelam honey scavenges peroxynitrite during the immune response

Kassim M, Mansor M, Suhaimi A, Ong G, Yusoff KM

Int J Mol Sci, 2012;13(9):12113-29.
PMID: 23109904 DOI: 10.3390/ijms130912113

Monocytes and macrophages are part of the first-line defense against bacterial, fungal, and viral infections during host immune responses; they express high levels of proinflammatory cytokines and cytotoxic molecules, including nitric oxide, reactive oxygen species, and their reaction product peroxynitrite. Peroxynitrite is a short-lived oxidant and a potent inducer of cell death. Honey, in addition to its well-known sweetening properties, is a natural antioxidant that has been used since ancient times in traditional medicine. We examined the ability of Gelam honey, derived from the Gelam tree (Melaleuca spp.), to scavenge peroxynitrite during immune responses mounted in the murine macrophage cell line RAW 264.7 when stimulated with lipopolysaccharide/interferon-γ (LPS/IFN-γ) and in LPS-treated rats. Gelam honey significantly improved the viability of LPS/IFN-γ-treated RAW 264.7 cells and inhibited nitric oxide production-similar to the effects observed with an inhibitor of inducible nitric oxide synthase (1400W). Furthermore, honey, but not 1400W, inhibited peroxynitrite production from the synthetic substrate 3-morpholinosydnonimine (SIN-1) and prevented the peroxynitrite-mediated conversion of dihydrorhodamine 123 to its fluorescent oxidation product rhodamine 123. Honey inhibited peroxynitrite synthesis in LPS-treated rats. Thus, honey may attenuate inflammatory responses that lead to cell damage and death, suggesting its therapeutic uses for several inflammatory disorders.
Ellagic acid, phenolic acids, and flavonoids in Malaysian honey extracts demonstrate in vitro anti-inflammatory activity

Kassim M, Achoui M, Mustafa MR, Mohd MA, Yusoff KM

Nutr Res, 2010 Sep;30(9):650-9.
PMID: 20934607 DOI: 10.1016/j.nutres.2010.08.008

Natural honey has been used in traditional medicine of different cultures throughout the world. This study looked into the extraction of Malaysian honey and the evaluation of the anti-inflammatory activity of these extracts. It was hypothesized that honey extracts contain varying amounts of phenolic compounds and that they possess different in vitro anti-inflammatory activities. Honey extracts were analyzed using liquid chromatography-mass spectrometry to identify and compare phenolic compounds, whereas high-performance liquid chromatography was used for their quantification. Subsequently, honey methanol extract (HME) and honey ethyl acetate extract (HEAE) were tested in vitro for their effect on nitric oxide production in stimulated macrophages. The extracts were also tested for their effects on tumor necrosis factor-α (TNF) cytotoxicity in L929 cells. The major phenolics in the extracts were ellagic, gallic, and ferulic acids; myricetin; chlorogenic acid; and caffeic acid. Other compounds found in lower concentrations were hesperetin, p-coumaric acid, chrysin, quercetin, luteolin, and kaempferol. Ellagic acid was the most abundant of the phenolic compounds recorded, with mean concentrations of 3295.83 and 626.74 μg/100 g of honey in HME and HEAE, respectively. The median maximal effective concentrations for in vitro nitric oxide inhibition by HEAE and HME were calculated to be 37.5 and 271.7 μg/mL, respectively. The median maximal effective concentrations for protection from TNF cytotoxicity by HEAE and HME were 168.1 and 235.4 μg/mL, respectively. In conclusion, HEAE exhibited greater activity in vitro, whereas HME contained a higher concentration of phenolic compounds per 100 g of honey.
Removal of iron and manganese by artificial destratification in a tropical climate (Upper Layang Reservoir, Malaysia)

Ismail R, Kassim MA, Inman M, Baharim NH, Azman S

Water Sci Technol, 2002;46(9):179-83.
PMID: 12448467

Environmental monitoring was carried out at Upper Layang Reservoir situated in Masai, Johor, Malaysia. The study shows that thermal stratification and natural mixing of the water column do exist in the reservoir and the level of stratification varies at different times of the year. Artificial destratification via diffused air aeration techniques was employed at the reservoir for two months. The results show that thermal stratification was eliminated after a week of continuous aeration. The concentrations of iron and to a lesser extent manganese in the water column was also reduced during the aeration period.
Fulltext Lead poisoning in childhood

Nasir HM, Kassim MS, Malinee T, Khairul AM, Low BH

Med J Malaysia, 1993 Sep;48(3):361-3.
PMID: 8183154

We report here a case of lead poisoning in a 20 month old girl who presented with acute encephalopathy and status epilepticus. The major clues leading to the diagnosis were the occupational family history and dense lead lines on X-ray of the long bones. She showed evidence of neurological dysfunction in the initial phase, but she improved steadily, regaining her motor power partially and her vision, although some cognitive and language deficits were already evident. She will need long-term neurological assessment and evaluation to ascertain the extent of permanent brain damage.
Analysis of Changes in Oil Palm Canopy Architecture From Basal Stem Rot Using Terrestrial Laser Scanner

Azuan NH, Khairunniza-Bejo S, Abdullah AF, Kassim MSM, Ahmad D

Plant Dis, 2019 Dec;103(12):3218-3225.
PMID: 31596688 DOI: 10.1094/PDIS-10-18-1721-RE

Basal stem rot (BSR), caused by the Ganoderma fungus, is an infectious disease that affects oil palm (Elaeis guineensis) plantations. BSR leads to a significant economic loss and reductions in yields of up to Malaysian Ringgit (RM) 1.5 billion (US$400 million) yearly. By 2020, the disease may affect ∼1.7 million tonnes of fresh fruit bunches. The plants appear symptomless in the early stages of infection, although most plants die after they are infected. Thus, early, accurate, and nondestructive disease detection is crucial to control the impact of the disease on yields. Terrestrial laser scanning (TLS) is an active remote-sensing, noncontact, cost-effective, precise, and user-friendly method. Through high-resolution scanning of a tree's dimension and morphology, TLS offers an accurate indicator for health and development. This study proposes an efficient image processing technique using point clouds obtained from TLS ground input data. A total of 40 samples (10 samples for each severity level) of oil palm trees were collected from 9-year-old trees using a ground-based laser scanner. Each tree was scanned four times at a distance of 1.5 m. The recorded laser scans were synched and merged to create a cluster of point clouds. An overhead two-dimensional image of the oil palm tree canopy was used to analyze three canopy architectures in terms of the number of pixels inside the crown (crown pixel), the degree of angle between fronds (frond angle), and the number of fronds (frond number). The results show that the crown pixel, frond angle, and frond number are significantly related and that the BSR severity levels are highly correlated (R2 = 0.76, P < 0.0001; R2 = 0.96, P < 0.0001; and R2 = 0.97, P < 0.0001, respectively). Analysis of variance followed post hoc tests by Student-Newman-Keuls (Newman-Keuls) and Dunnett for frond number presented the best results and showed that all levels were significantly different at a 5% significance level. Therefore, the earliest stage that a Ganoderma infection could be detected was mildly infected (T1). For frond angle, all post hoc tests showed consistent results, and all levels were significantly separated except for T0 and T1. By using the crown pixel parameter, healthy trees (T0) were separated from unhealthy trees (moderate infection [T2] and severe infection [T3]), although there was still some overlap with T1. Thus, Ganoderma infection could be detected as early as the T2 level by using the crown pixel and the frond angle parameters. It is hard to differentiate between T0 and T1, because during mild infection, the symptoms are highly similar. Meanwhile, T2 and T3 were placed in the same group, because they showed the same trend. This study demonstrates that the TLS is useful for detecting low-level infection as early as T1 (mild severity). TLS proved beneficial in managing oil palm plantation disease.
Gelam honey inhibits lipopolysaccharide-induced endotoxemia in rats through the induction of heme oxygenase-1 and the inhibition of cytokines, nitric oxide, and high-mobility group protein B1

Kassim M, Yusoff KM, Ong G, Sekaran S, Yusof MY, Mansor M

Fitoterapia, 2012 Sep;83(6):1054-9.
PMID: 22626749 DOI: 10.1016/j.fitote.2012.05.008

Malaysian Gelam honey has anti-inflammatory and antibacterial properties, a high antioxidant capacity, and free radical-scavenging activity. Lipopolysaccharide (LPS) stimulates immune cells to sequentially release early pro- and anti-inflammatory cytokines and induces the synthesis of several related enzymes. The aim of this study was to investigate the effect of the intravenous injection of honey in rats with LPS-induced endotoxemia. The results showed that after 4h of treatment, honey reduced cytokine (tumor necrosis factor-α, interleukins 1β, and 10) and NO levels and increased heme oxygenase-1 levels. After 24h, a decrease in cytokines and NO and an increase in HO-1 were seen in all groups, whereas a reduction in HMGB1 occurred only in the honey-treated groups. These results support the further examination of honey as a natural compound for the treatment of a wide range of inflammatory diseases.
Fulltext Antioxidant, antibacterial activity, and phytochemical characterization of Melaleuca cajuputi extract

Al-Abd NM, Mohamed Nor Z, Mansor M, Azhar F, Hasan MS, Kassim M

BMC Complement Altern Med, 2015;15:385.
PMID: 26497742 DOI: 10.1186/s12906-015-0914-y

The threat posed by drug-resistant pathogens has resulted in the increasing momentum in research and development for effective alternative medications. The antioxidant and antibacterial properties of phytochemical extracts makes them attractive alternative complementary medicines. Therefore, this study evaluated the phytochemical constituents of Melaleuca cajuputi flower and leaf (GF and GL, respectively) extracts and their antioxidant and antibacterial activities.
Fulltext Prevalence of filarial parasites in domestic and stray cats in Selangor State, Malaysia

Al-Abd NM, Nor ZM, Kassim M, Mansor M, Al-Adhroey AH, Ngui R, et al.

Asian Pac J Trop Med, 2015 Sep;8(9):705-9.
PMID: 26433654 DOI: 10.1016/j.apjtm.2015.07.034

OBJECTIVE: To determine the prevalence of the filarial parasites,ie.,Brugia malayi, Brugia, Brugia pahangi(B. pahangi), Dirofilaria immitisandDirofilaria repens (D. repens) in domestic and stray cats.
METHODS: A total of 170 blood sample were collected from domestic and stray cats and examined for filarial worm parasites in two localities, Pulau Carey and Bukit Gasing, Selangor State, Malaysia.
RESULTS: The overall prevalence of infection was 23.5% (40/170; 95% CI = 17.4-30.6). Of this, 35% (14/40; 95% CI = 22.1-50.5) and 50% (20/40; 95% CI = 35.2-64.8) were positive for single B. pahangi nd D. repens, respectively. The remaining of 15% (6/40; 95% CI = 7.1-29.1) were positive for mixed B. pahangi and D. repens. In addition, 75% of the infected cats were domestic, and 25% were strays. No Brugia malayi and Dirofilaria immitis was detected. Eighty-four cats were captured at Pulau Carey, of which 35.7% (30/84) were infected. Among the cats determined to be infected, 93% (28/30; 95% CI = 78.7-98.2) were domestic, and only 6.7% (2/30; 95% CI = 19.0-21.3) were strays. Conversely, the number of infected cats was three times lower in Bukit Gasing than in Pulau Carey, and most of the cats were stray.
CONCLUSIONS: B. pahangi and D. repens could be the major parasites underlying filariasis in the study area. Adequate prophylactic plans should be administrated in the cat population in study area.
Fulltext Child abuse and neglect as seen in General Hospital, Kuala Lumpur--a two year study

Kassim MS, George R, Kassim K, Begum M, Cherian MP, Tajudin AK, et al.

Med J Malaysia, 1989 Jun;44(2):111-21.
PMID: 2626119

Eighty-six children diagnosed as child abuse and/or neglect were admitted to the Paediatric wards of the General Hospital, Kuala Lumpur during 1985 and 1986. Of these cases, 62 were of physical abuse, six of sexual abuse, one case of both physical and sexual abuse and 17 of neglect. There were 25 boys and 61 girls. Thirty-four of these children were Malays, 16 Chinese, 26 Indians, three mixed and seven illegal immigrants. Twenty-one were below the age of one year, 24 from one to four years, 25 from five to nine years and 16 were ten years and above. The abusers were mainly close members of the family. Of these children, 24 were sent back to their parents and 11 to their relatives home. Twenty-seven were taken into care by the Ministry of Social Welfare and the remaining seven children who were illegal immigrants, were deported with their parents. Only one child was successfully fostered. Eleven children were taken away from the hospital by their parents or guardians without the knowledge of the health staff. There were five deaths in the series.
Fulltext Inhibitory effects of biofeedback electrostimulation therapy on pain and cortisol levels in chronic neuropathic pain: A randomized-controlled trial

Mansor M, Shan Lee Z, San LP, Mei Ng M, Al-Abd N, Kassim M

Turk J Phys Med Rehabil, 2021 Mar;67(1):62-68.
PMID: 33948545 DOI: 10.5606/tftrd.2021.4672

Objectives: This study aims to investigate the effectiveness of biofeedback electrostimulation therapy (BEST) in chronic neuropathic pain and to evaluate changes in perceived level of pain and level of blood cortisol before and after treatment.
Patients and methods: This single-blind, prospective, randomized-controlled study included a total of 20 patients (8 males, 12 females; mean age: 53.5±13.8; range, 31 to 82 years) with chronic neuropathic pain between January 2014 and June 2014. The patients were randomized to BEST (n=10) or placebo (n=10) group. Pain was measured using the Visual Analog Scale, and serum cortisol levels were measured before and after treatment.
Results: There was no significant difference in the baseline demographics, diagnosis, and treatment modalities between the groups. Approximately 50% patients in the treatment group reported that the treatment was effective, compared to 30% in the placebo group. Pain score reduction after treatment in the BEST group was significant (p<0.05), while it was not significant in the placebo group (p=0.4). Cortisol levels significantly reduced only in the BEST group after treatment (p=0.013).
Conclusion: The BEST yields reduction in pain severity and cortisol levels. Based on these results, it seems to be effective in the treatment of chronic neuropathic pain after a single treatment and may be more effective for long-term management.
Severe central airway stenosis and tracheomalacia in hunter syndrome

Tan HL, Abd Rahman R, Md Tarekh NA, Kassim M, Sathiamurthy N, Nik Mohamad Kamil A, et al.

Med J Malaysia, 2021 05;76(3):441-445.
PMID: 34031351

Hunter Syndrome is a genetic disease characterized by deficiency of Iduronate-2-Sulfatase enzyme activity, resulting in accumulation of glycoaminoglycans in various organs including the central airways. We report a case of severe tracheomalacia and airway stenosis at Hospital Sultanah Aminah, Johor Bahru, Malaysia requiring mechanical ventilation in a middle aged gentleman who was previously undiagnosed of mucopolysaccharidosis. The patient underwent emergency tracheostomy for failed intubation, when he presented with shortness of breath and acute respiratory failure. A contrast-enhanced computed tomography of the neck and thorax revealed that the trachea distal to the tracheostomy tube had collapsed with narrowed right and left main bronchus. These findings were confirmed via direct visualization of the airway through a flexible bronchoscopy. Eventually, a tracheal stenting were performed to maintain the airway patency and assist in weaning off from mechanical ventilation. Further investigations to identify the aetiology of the central airway stenosis revealed elevated urinary glycoaminoglycans and the absence of iduronate-2-Sulfatase activity tested on dried blood spots, thus confirming the diagnosis of Hunter Syndrome. Managing mucopolysacharidosis with central airway obstruction requires multidisciplinary team effort in handling the difficult airway, anaesthesiology risk, potential comorbidities and providing genetic counselling.
Fulltext Concurrence of symmetrical peripheral gangrene and venous limb gangrene following polytrauma: a case report

Tan JH, Mohamad Y, Tan CLH, Kassim M, Warkentin TE

J Med Case Rep, 2018 May 19;12(1):131.
PMID: 29776439 DOI: 10.1186/s13256-018-1684-1

BACKGROUND: Symmetrical peripheral gangrene is characterized as acral (distal extremity) ischemic limb injury affecting two or more extremities, without large vessel obstruction, typically in a symmetrical fashion. Risk factors include hypotension, disseminated intravascular coagulation, and acute ischemic hepatitis ("shock liver"). In contrast, venous limb gangrene is characterized by acral ischemic injury occurring in a limb with deep vein thrombosis. Both symmetrical peripheral gangrene and venous limb gangrene present as acral limb ischemic necrosis despite presence of arterial pulses. The coexistence of symmetrical peripheral gangrene and venous limb gangrene is rare, with potential to provide pathophysiological insights.
CASE PRESENTATION: A 42-year-old Chinese man presented with polytrauma (severe head injury, lung contusions, and right femur fracture). Emergency craniotomy and debridement of right thigh wound were performed on presentation. Intraoperative hypotension secondary to bleeding was complicated by transient need for vasopressors and acute liver enzyme elevation indicating shock liver. Beginning on postoperative day 5, he developed an acute platelet count fall (from 559 to 250 × 109/L over 3 days) associated with left iliofemoral deep vein thrombosis that evolved to bilateral lower limb ischemic necrosis; ultimately, the extent of limb ischemic injury was greater in the left (requiring below-knee amputation) versus the right (transmetatarsal amputation). As the presence of deep vein thrombosis is a key feature known to localize microthrombosis and hence ischemic injury in venous limb gangrene, the concurrence of unilateral lower limb deep vein thrombosis in a typical clinical setting of symmetrical peripheral gangrene (hypotension, proximate shock liver, platelet count fall consistent with disseminated intravascular coagulation) helps to explain asymmetric limb injury - manifesting as a greater degree of ischemic necrosis and extent of amputation in the limb affected by deep vein thrombosis - in a patient whose clinical picture otherwise resembled symmetrical peripheral gangrene.
CONCLUSIONS: Concurrence of unilateral lower limb deep vein thrombosis in a typical clinical setting of symmetrical peripheral gangrene is a potential explanation for greater extent of acral ischemic injury in the limb affected by deep vein thrombosis.
Fulltext Antifilarial and Antibiotic Activities of Methanolic Extracts of Melaleuca cajuputi Flowers

Al-Abd NM, Nor ZM, Mansor M, Hasan MS, Kassim M

Korean J Parasitol, 2016 Jun;54(3):273-80.
PMID: 27417081 DOI: 10.3347/kjp.2016.54.3.273

We evaluated the activity of methanolic extracts of Melaleuca cajuputi flowers against the filarial worm Brugia pahangi and its bacterial endosymbiont Wolbachia. Anti-Wolbachia activity was measured in worms and in Aedes albopictus Aa23 cells by PCR, electron microscopy, and other biological assays. In particular, microfilarial release, worm motility, and viability were determined. M. cajuputi flower extracts were found to significantly reduce Wolbachia endosymbionts in Aa23 cells, Wolbachia surface protein, and microfilarial release, as well as the viability and motility of adult worms. Anti-Wolbachia activity was further confirmed by observation of degraded and phagocytized Wolbachia in worms treated with the flower extracts. The data provided in vitro and in vivo evidence that M. cajuputi flower extracts inhibit Wolbachia, an activity that may be exploited as an alternative strategy to treat human lymphatic filariasis.
Fulltext Antifilarial activity of caffeic acid phenethyl ester on Brugia pahangi in vitro and in vivo

Al-Abd NM, Nor ZM, Junaid QO, Mansor M, Hasan MS, Kassim M

Pathog Glob Health, 2017 Oct;111(7):388-394.
PMID: 29065795 DOI: 10.1080/20477724.2017.1380946

Lymphatic filariasis (LF) is a vector borne disease caused by parasitic worms such as Wuchereria bancrofti, Brugia malayi and B. timori, which are transmitted by mosquitoes. Current therapeutics to treat LF are mainly microfilarcidal, and lack activity against adult worms. This set back, poses a challenge for the control and elimination of filariasis. Thus, in this study the activities of caffeic acid phenethyl ester (CAPE) against the filarial worm B. pahangi and its bacterial endosymbiont, Wolbachia were evaluated. Different concentrations (2, 5, 10, 15, 20 μg/ml) of CAPE were used to assess its effects on motility, viability and microfilarial (mf) production of B. pahangi in vitro. Anti-Wolbachial activity of CAPE was measured in worms by quantification of Wolbachial wsp gene copy number using real-time polymerase chain reaction. Our findings show that CAPE was found to significantly reduce adult worm motility, viability, and mf release both in vitro and in vivo. 20 μg/ml of CAPE halts the release of mf in vitro by day 6 of post treatment. Also, the number of adult worms recovered in vivo were reduced significantly during and after treatment with 50 mg/kg of CAPE relative to control drugs, diethylcarbamazine and doxycycline. Real time PCR based on the Wolbachia ftsZ gene revealed a significant reduction in Wolbachia copy number upon treatment. Anti-Wolbachia and antifilarial properties of CAPE require further investigation as an alternative strategy to treat LF.
Vertical MoS2on SiO2/Si and Graphene: Effect of Surface Morphology on Photoelectrochemical Properties

Rosman NN, Mohamad Yunus R, Jeffery Minggu L, Arifin K, B Kassim M, Mohamed MA

Nanotechnology, 2020 Oct 06.
PMID: 33022666 DOI: 10.1088/1361-6528/abbea9

Two-dimensional materials have attracted intensive attention recently due to their unique optical and electronic properties and their promising applications in water splitting and solar cells. As a representative layer-structured of transition metal dichalcogenides, MoS2has attracted considerable devotion owing to its exceptional photo and electro properties. Here, we show that the chemical vapour deposition (CVD) growth of MoS2on Si photocathode and graphene/Si photocathode can be used to prepare photoelectrocatalysts for water splitting. We explore a bottom-up method to grow vertical heterostructures of MoS2and graphene by using the two-step CVD. Graphene is first grown through ambient-pressure CVD on a Cu substrate and then transferred onto SiO2/Si substrate by using the chemical wet transfer followed by the second CVD method to grow MoS2over the graphene/SiO2/Si. The effect of the growth temperatures of MoS2is studied, and the optimum temperature is 800 °C. The MoS2produced at 800 °C has the highest photocurrent density at -0.23 mA cm-2in 0.5 M Na2SO4and -0.51 mA cm-2in 0.5 M H2SO4at -0.8 V vs. Ag/AgCl. The linear sweep voltammetry shows that MoS2in 0.5 M H2SO4has about 55% higher photocurrent density than MoS2in Na2SO4due to the higher protons (H+) in the H2SO4electrolyte solution, which are sufficiently charged to reduce to H2and, therefore hydrogen evolves more rapidly where the photocurrent density and hydrogen generation can be enhanced. MoS2/graphene/SiO2/Si (MGS) has -0.07 mA cm-2at -0.8 V vs. Ag/AgCl of photocurrent density, which is 70% lower than that of bare MoS2because MGS is thicker compared with MoS2. Thus, MoS2has potential as a photocatalyst in photoelectrochemical water splitting. The structure and the morphology of MoS2play an important role in determining the photocurrent performance.
Fulltext Lymphatic filariasis in Peninsular Malaysia: a cross-sectional survey of the knowledge, attitudes, and practices of residents

Al-Abd NM, Nor ZM, Ahmed A, Al-Adhroey AH, Mansor M, Kassim M

Parasit Vectors, 2014;7:545.
PMID: 25428558 DOI: 10.1186/s13071-014-0545-z

Lymphatic filariasis (LF) is a major cause of permanent disability in many tropical and sub-tropical countries of the world. Malaysia is one of the countries in which LF is an endemic disease. Five rounds of the mass drug administration (MDA) program have been conducted in Malaysia as part of the Global Program to Eliminate Lymphatic Filariasis (GPELF) by year 2020. This study investigated the level of awareness of LF and the MDA program in a population living in an endemic area of the country.

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