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Fulltext Improved properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) produced by Comamonas sp. EB172 utilizing volatile fatty acids by regulating the nitrogen source

Zakaria MR, Ariffin H, Abd-Aziz S, Hassan MA, Shirai Y

Biomed Res Int, 2013;2013:237806.
PMID: 24106698 DOI: 10.1155/2013/237806

This study presents the effect of carbon to nitrogen ratio (C/N) (mol/mol) on the cell growth and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) accumulation by Comamonas sp. EB172 in 2 L fermenters using volatile fatty acids (VFA) as the carbon source. This VFA was supplemented with ammonium sulphate and yeast extract in the feeding solution to achieve C/N (mol/mol) 5, 15, 25, and 34.4, respectively. By extrapolating the C/N and the source of nitrogen, the properties of the polymers can be regulated. The number average molecular weight (M n ) of P(3HB-co-3HV) copolymer reached the highest at 838 × 10(3) Da with polydispersity index (PDI) value of 1.8, when the culture broth was supplemented with yeast extract (C/N 34.4). Tensile strength and Young's modulus of the copolymer containing 6-8 mol% 3HV were in the ranges of 13-14.4 MPa and 0.26-0.34 GPa, respectively, comparable to those of polyethylene (PE). Thus, Comamonas sp. EB172 has shown promising bacterial isolates producing polyhydroxyalkanoates from renewable carbon materials.
Renewable sugars from oil palm frond juice as an alternative novel fermentation feedstock for value-added products

Zahari MA, Zakaria MR, Ariffin H, Mokhtar MN, Salihon J, Shirai Y, et al.

Bioresour Technol, 2012 Apr;110:566-71.
PMID: 22342083 DOI: 10.1016/j.biortech.2012.01.119

In this paper, we report that pressed juice from oil palm frond (OPF) contained renewable sugars such as glucose, sucrose and fructose. By using a simple sugarcane press, 50% (wt/wt) of OPF juice was obtained from fresh OPF. The glucose content in the juice was 53.95±2.86g/l, which accounts for 70% of the total free sugars. We have examined the effect of various OPF juice concentrations on the production of poly(3-hydroxybutyrate), P(3HB) by Cupriavidus necator CCUG 52238(T). The cell dry mass in shake flask experiment reached 8.42g/l, with 32wt.% of P(3HB) at 30% (v/v) of OPF juice, comparable with using technical grade sugars. The biopolymer had a molecular mass, M(w) of 812kDa, with a low polydispersity index of 1.61. This result indicates that OPF juice can be used as an alternative renewable carbon source for P(3HB) production and has potential as a renewable carbon source.
Intensifying Treatment of Childhood B-Lymphoblastic Leukemia With IKZF1 Deletion Reduces Relapse and Improves Overall Survival: Results of Malaysia-Singapore ALL 2010 Study

Yeoh AEJ, Lu Y, Chin WHN, Chiew EKH, Lim EH, Li Z, et al.

J Clin Oncol, 2018 09 10;36(26):2726-2735.
PMID: 30044693 DOI: 10.1200/JCO.2018.78.3050

Purpose Although IKZF1 deletion ( IKZF1del) confers a higher risk of relapse in childhood B-cell acute lymphoblastic leukemia (B-ALL), it is uncertain whether treatment intensification will reverse this risk and improve outcomes. The Malaysia-Singapore ALL 2010 study (MS2010) prospectively upgraded the risk assignment of patients with IKZF1del to the next highest level and added imatinib to the treatment of all patients with BCR- ABL1 fusion. Patients and Methods In total, 823 patients with B-ALL treated in the Malyasia-Singapore ALL 2003 study (MS2003; n = 507) and MS2010 (n = 316) were screened for IKZF1del using the multiplex ligation-dependent probe amplification assay. The impact of IKZF1del on the 5-year cumulative incidence of relapse (CIR) was compared between the two studies. Results Patient characteristics were similar in both cohorts, including IKZF1del frequencies (59 of 410 [14.4%] v 50 of 275 [18.2%]; P = .2). In MS2003, where IKZF1del was not used in risk assignment, IKZF1del conferred a significantly higher 5-year CIR (30.4% v 8.1%; P = 8.7 × 10-7), particularly in the intermediate-risk group who lacked high-risk features (25.0% v 7.5%; P = .01). For patients with BCR-ABL1-negative disease, IKZF1del conferred a higher 5-year CIR (20.5% v 8.0%; P = .01). In MS2010, the 5-year CIR of patients with IKZF1del significantly decreased to 13.5% ( P = .05) and no longer showed a significant difference in patients with BCR-ABL1-negative disease (11.4% v 4.4%; P = .09). The 5-year overall survival for patients with IKZF1del improved from 69.6% in MS2003 to 91.6% in MS2010 ( P = .007). Conclusion Intensifying therapy for childhood B-ALL with IKZF1del significantly reduced the risk of relapse and improved overall survival. Incorporating IKZF1del screening significantly improved treatment outcomes in contemporary ALL therapy.
Doing less, accomplishing more for childhood acute lymphoblastic leukaemia (ALL)

Yeoh AEJ, Oh BL, Ariffin H

Br J Haematol, 2021 08;194(4):661-662.
PMID: 34231199 DOI: 10.1111/bjh.17556
Fulltext Minimal residual disease-guided treatment deintensification for children with acute lymphoblastic leukemia: results from the Malaysia-Singapore acute lymphoblastic leukemia 2003 study

Yeoh AE, Ariffin H, Chai EL, Kwok CS, Chan YH, Ponnudurai K, et al.

J Clin Oncol, 2012 Jul 1;30(19):2384-92.
PMID: 22614971 DOI: 10.1200/JCO.2011.40.5936

PURPOSE: To improve treatment outcome for childhood acute lymphoblastic leukemia (ALL), we designed the Malaysia-Singapore ALL 2003 study with treatment stratification based on presenting clinical and genetic features and minimal residual disease (MRD) levels measured by polymerase chain reaction targeting a single antigen-receptor gene rearrangement.
PATIENTS AND METHODS: Five hundred fifty-six patients received risk-adapted therapy with a modified Berlin-Frankfurt-Münster-ALL treatment. High-risk ALL was defined by MRD ≥ 1 × 10(-3) at week 12 and/or poor prednisolone response, BCR-ABL1, MLL gene rearrangements, hypodiploid less than 45 chromosomes, or induction failure; standard-risk ALL was defined by MRD ≤ 1 × 10(-4) at weeks 5 and 12 and no extramedullary involvement or high-risk features. Intermediate-risk ALL included all remaining patients.
RESULTS: Patients who lacked high-risk presenting features (85.7%) received remission induction therapy with dexamethasone, vincristine, and asparaginase, without anthracyclines. Six-year event-free survival (EFS) was 80.6% ± 3.5%; overall survival was 88.4% ± 3.1%. Standard-risk patients (n = 172; 31%) received significantly deintensified subsequent therapy without compromising EFS (93.2% ± 4.1%). High-risk patients (n = 101; 18%) had the worst EFS (51.8% ± 10%); EFS was 83.6% ± 4.9% in intermediate-risk patients (n = 283; 51%).
CONCLUSION: Our results demonstrate significant progress over previous trials in the region. Three-drug remission-induction therapy combined with MRD-based risk stratification to identify poor responders is an effective strategy for childhood ALL.
Genetic susceptibility to childhood acute lymphoblastic leukemia shows protection in Malay boys: results from the Malaysia-Singapore ALL Study Group

Yeoh AE, Lu Y, Chan JY, Chan YH, Ariffin H, Kham SK, et al.

Leuk. Res., 2010 Mar;34(3):276-83.
PMID: 19651439 DOI: 10.1016/j.leukres.2009.07.003

To study genetic epidemiology of childhood acute lymphoblastic leukemia (ALL) in the Chinese and Malays, we investigated 10 polymorphisms encoding carcinogen- or folate-metabolism and transport. Sex-adjusted analysis showed NQO1 609CT significantly protects against ALL, whilst MTHFR 677CT confers marginal protection. Interestingly, we observed that NQO1 609CT and MTHFR 1298 C-allele have greater genetic impact in boys than in girls. The combination of SLC19A1 80GA heterozygosity and 3'-TYMS -6bp/-6bp homozygous deletion is associated with reduced ALL risk in Malay boys. Our study has suggested the importance of gender and race in modulating ALL susceptibility via the folate metabolic pathway.
Effective Response Metric: a novel tool to predict relapse in childhood acute lymphoblastic leukaemia using time-series gene expression profiling

Yeoh AE, Li Z, Dong D, Lu Y, Jiang N, Trka J, et al.

Br J Haematol, 2018 Jun;181(5):653-663.
PMID: 29808917 DOI: 10.1111/bjh.15252

Accurate risk assignment in childhood acute lymphoblastic leukaemia is essential to avoid under- or over-treatment. We hypothesized that time-series gene expression profiles (GEPs) of bone marrow samples during remission-induction therapy can measure the response and be used for relapse prediction. We computed the time-series changes from diagnosis to Day 8 of remission-induction, termed Effective Response Metric (ERM-D8) and tested its ability to predict relapse against contemporary risk assignment methods, including National Cancer Institutes (NCI) criteria, genetics and minimal residual disease (MRD). ERM-D8 was trained on a set of 131 patients and validated on an independent set of 79 patients. In the independent blinded test set, unfavourable ERM-D8 patients had >3-fold increased risk of relapse compared to favourable ERM-D8 (5-year cumulative incidence of relapse 38·1% vs. 10·6%; P = 2·5 × 10-3 ). ERM-D8 remained predictive of relapse [P = 0·05; Hazard ratio 4·09, 95% confidence interval (CI) 1·03-16·23] after adjusting for NCI criteria, genetics, Day 8 peripheral response and Day 33 MRD. ERM-D8 improved risk stratification in favourable genetics subgroups (P = 0·01) and Day 33 MRD positive patients (P = 1·7 × 10-3 ). We conclude that our novel metric - ERM-D8 - based on time-series GEP after 8 days of remission-induction therapy can independently predict relapse even after adjusting for NCI risk, genetics, Day 8 peripheral blood response and MRD.
Fulltext Well-Dispersed Cellulose Nanofiber in Low Density Polyethylene Nanocomposite by Liquid-Assisted Extrusion

Yasim-Anuar TAT, Ariffin H, Norrrahim MNF, Hassan MA, Andou Y, Tsukegi T, et al.

Polymers (Basel), 2020 Apr 17;12(4).
PMID: 32316664 DOI: 10.3390/polym12040927

Two different liquid assisted processing methods: internal melt-blending (IMB) and twin-screw extrusion (TWS) were performed to fabricate polyethylene (PE)/cellulose nanofiber (CNF) nanocomposites. The nanocomposites consisted maleic anhydride-grafted PE (PEgMA) as a compatibilizer, with PE/PEgMA/CNF ratio of 97/3/0.5-5 (wt./wt./wt.), respectively. Morphological analysis exhibited that CNF was well-dispersed in nanocomposites prepared by liquid-assisted TWS. Meanwhile, a randomly oriented and agglomerated CNF was observed in the nanocomposites prepared by liquid-assisted IMB. The nanocomposites obtained from liquid-assisted TWS exhibited the best mechanical properties at 3 wt.% CNF addition with an increment in flexural strength by almost 139%, higher than that of liquid-assisted IMB. Results from this study indicated that liquid feeding of CNF assisted the homogenous dispersion of CNF in PE matrix, and the mechanical properties of the nanocomposites were affected by compounding method due to the CNF dispersion and alignment.
Cellular and Molecular Interaction of Human Dermal Fibroblasts with Bacterial Nanocellulose Composite Hydrogel for Tissue Regeneration

Xi Loh EY, Fauzi MB, Ng MH, Ng PY, Ng SF, Ariffin H, et al.

ACS Appl Mater Interfaces, 2018 Nov 21;10(46):39532-39543.
PMID: 30372014 DOI: 10.1021/acsami.8b16645

The evaluation of the interaction of cells with biomaterials is fundamental to establish the suitability of the biomaterial for a specific application. In this study, the properties of bacterial nanocellulose/acrylic acid (BNC/AA) hydrogels fabricated with varying BNC to AA ratios and electron-beam irradiation doses were determined. The manner these hydrogel properties influence the behavior of human dermal fibroblasts (HDFs) at the cellular and molecular levels was also investigated, relating it to its application both as a cell carrier and wound dressing material. Swelling, hardness, adhesive force (wet), porosity, and hydrophilicity (dry) of the hydrogels were dependent on the degree of cross-linking and the amount of AA incorporated in the hydrogels. However, water vapor transmission rate, pore size, hydrophilicity (semidry), and topography were similar between all formulations, leading to a similar cell attachment and proliferation profile. At the cellular level, the hydrogel demonstrated rapid cell adhesion, maintained HDFs viability and morphology, restricted cellular migration, and facilitated fast transfer of cells. At the molecular level, the hydrogel affected nine wound-healing genes (IL6, IL10, MMP2, CTSK, FGF7, GM-CSF, TGFB1, COX2, and F3). The findings indicate that the BNC/AA hydrogel is a potential biomaterial that can be employed as a wound-dressing material to incorporate HDFs for the acceleration of wound healing.
Fulltext The influence of green surface modification of oil palm mesocarp fiber by superheated steam on the mechanical properties and dimensional stability of oil palm mesocarp fiber/poly(butylene succinate) biocomposite

Then YY, Ibrahim NA, Zainuddin N, Ariffin H, Yunus WM, Chieng BW

Int J Mol Sci, 2014;15(9):15344-57.
PMID: 25177865 DOI: 10.3390/ijms150915344

In this paper, superheated steam (SHS) was used as cost effective and green processing technique to modify oil palm mesocarp fiber (OPMF) for biocomposite applications. The purpose of this modification was to promote the adhesion between fiber and thermoplastic. The modification was carried out in a SHS oven at various temperature (200-230 °C) and time (30-120 min) under normal atmospheric pressure. The biocomposites from SHS-treated OPMFs and poly(butylene succinate) (PBS) at a weight ratio of 70:30 were prepared by melt blending technique. The mechanical properties and dimensional stability of the biocomposites were evaluated. This study showed that the SHS treatment increased the roughness of the fiber surface due to the removal of surface impurities and hemicellulose. The tensile, flexural and impact properties, as well as dimensional stability of the biocomposites were markedly enhanced by the presence of SHS-treated OPMF. Scanning electron microscopy analysis showed improvement of interfacial adhesion between PBS and SHS-treated OPMF. This work demonstrated that SHS could be used as an eco-friendly and sustainable processing method for modification of OPMF in biocomposite fabrication.
Succinic Semialdehyde Dehydrogenase Deficiency in a Chinese Boy: A Novel ALDH5A1 Mutation With Severe Phenotype

Tay CG, Ariffin H, Yap S, Rahmat K, Sthaneshwar P, Ong LC

J Child Neurol, 2015 Jun;30(7):927-31.
PMID: 25122112 DOI: 10.1177/0883073814540523

Succinic semialdehyde dehydrogenase deficiency is a rare autosomal recessive disorder affecting catabolism of the neurotransmitter gamma-aminobutyric acid (GABA), with a wide range of clinical phenotype. We report a Malaysian Chinese boy with a severe early onset phenotype due to a previously unreported mutation. Urine organic acid chromatogram revealed elevated 4-hydroxybutyric acid. Magnetic resonance imaging (MRI) of the brain demonstrated cerebral atrophy with atypical putaminal involvement. Molecular genetic analysis showed a novel homozygous 3-bp deletion at the ALDH5A1 gene c.1501_1503del (p.Glu501del). Both parents were confirmed to be heterozygotes for the p.Glu501del mutation. The clinical course was complicated by the development of subdural hemorrhage probably as a result of rocking the child to sleep for erratic sleep-wake cycles. This case illustrates the need to recognize that trivial or unintentional shaking of such children, especially in the presence of cerebral atrophy, can lead to subdural hemorrhage.
Vincristine-induced peripheral neuropathy in survivors of childhood acute lymphoblastic leukaemia

Tay CG, Lee VWM, Ong LC, Goh KJ, Ariffin H, Fong CY

Pediatr Blood Cancer, 2017 Aug;64(8).
PMID: 28139029 DOI: 10.1002/pbc.26471

BACKGROUND: Vincristine, an essential component of childhood acute lymphoblastic leukaemia (ALL) therapeutic protocols, is associated with dose-dependent neurotoxicity, but its long-term morbidity in treated children has not been clearly elucidated. The aim of this study is to determine the prevalence of vincristine-induced peripheral neuropathy (VIPN) among Malaysian childhood ALL survivors and its impact on motor function and quality of life.
PROCEDURE: Survivors of childhood ALL aged 4-18 years who had completed chemotherapy for 2 years or more were evaluated for VIPN using both the clinical Total Neuropathy Score (cTNS) and nerve conduction studies. Motor function and quality of life of the survivors were assessed via the Bruininks-Oseretsky Test of Motor Proficiency Brief Form, Second Edition (BOT-2 Brief Form) and the Paediatric Quality of Life version 4.0 Generic Core Scales (PedsQL4.0) questionnaire, respectively.
RESULTS: One hundred and one survivors with a duration of follow-up ranging from 2.0 to 10.3 years were recruited. Twenty-seven (26.7%) had abnormal cTNS scores and 69 (68.3%) had electrophysiological evidence of neuropathy. Of these, 16 (15.8%) had combined clinical and electrophysiological neuropathy (VIPN). Those previously treated on the intermediate- or high-risk treatment stratification arms had a higher risk of developing VIPN (67.3 vs. 32.7%; odds ratio [OR]: 9.06, 95% confidence interval [CI]: 1.14-71.86; P = 0.014). Survivors with VIPN had significantly lower quality of life scores in the physical (P = 0.024) and social domains (P = 0.039) compared with peers without VIPN, but no association with poorer motor function was observed.
CONCLUSIONS: Sixteen percent of ALL survivors had VIPN. VIPN should be increasingly recognised as a late effect of chemotherapy, as it significantly affects physical and social function quality of life.
Fulltext An international retrospective study for tolerability of 6-mercaptopurine on NUDT15 bi-allelic variants in children with acute lymphoblastic leukemia

Tanaka Y, Yeoh AEJ, Moriyama T, Li CK, Kudo K, Arakawa Y, et al.

Haematologica, 2021 07 01;106(7):2026-2029.
PMID: 33504140 DOI: 10.3324/haematol.2020.266320
Fulltext Spontaneous splenic rupture secondary to phaeyohyphomycosis and splenic abscesses

Sithasanan N, Chong LA, Ariffin H

Med J Malaysia, 2007 Aug;62(3):247-8.
PMID: 18246918 MyJurnal

Phaeohyphomycosis consists of a group of mycotic infections characterized by the presence of dematiaceous (dark walled) septate hyphae. Splenic abscess and spontaneous rupture is an infrequent complication in children with haematological malignancies and can be life threatening. To the best of our knowledge this is the first report of a case of splenic rupture following the development of multiple abscesses secondary to infestation by this rare fungal species.
Fulltext Functionality of Cellulose Nanofiber as Bio-Based Nucleating Agent and Nano-Reinforcement Material to Enhance Crystallization and Mechanical Properties of Polylactic Acid Nanocomposite

Shazleen SS, Yasim-Anuar TAT, Ibrahim NA, Hassan MA, Ariffin H

Polymers (Basel), 2021 Jan 27;13(3).
PMID: 33513688 DOI: 10.3390/polym13030389

Polylactic acid (PLA), a potential alternative material for single use plastics, generally portrays a slow crystallization rate during melt-processing. The use of a nanomaterial such as cellulose nanofibers (CNF) may affect the crystallization rate by acting as a nucleating agent. CNF at a certain wt.% has been evidenced as a good reinforcement material for PLA; nevertheless, there is a lack of information on the correlation between the amount of CNF in PLA that promotes its functionality as reinforcement material, and its effect on PLA nucleation for improving the crystallization rate. This work investigated the nucleation effect of PLA incorporated with CNF at different fiber loading (1-6 wt.%) through an isothermal and non-isothermal crystallization kinetics study using differential scanning calorimetry (DSC) analysis. Mechanical properties of the PLA/CNF nanocomposites were also investigated. PLA/CNF3 exhibited the highest crystallization onset temperature and enthalpy among all the PLA/CNF nanocomposites. PLA/CNF3 also had the highest crystallinity of 44.2% with an almost 95% increment compared to neat PLA. The highest crystallization rate of 0.716 min-1 was achieved when PLA/CNF3 was isothermally melt crystallized at 100 °C. The crystallization rate was 65-fold higher as compared to the neat PLA (0.011 min-1). At CNF content higher than 3 wt.%, the crystallization rate decreased, suggesting the occurrence of agglomeration at higher CNF loading as evidenced by the FESEM micrographs. In contrast to the tensile properties, the highest tensile strength and Young's modulus were recorded by PLA/CNF4 at 76.1 MPa and 3.3 GPa, respectively. These values were, however, not much different compared to PLA/CNF3 (74.1 MPa and 3.3 GPa), suggesting that CNF at 3 wt.% can be used to improve both the crystallization rate and the mechanical properties. Results obtained from this study revealed the dual function of CNF in PLA nanocomposite, namely as nucleating agent and reinforcement material. Being an organic and biodegradable material, CNF has an increased advantage for use in PLA as compared to non-biodegradable material and is foreseen to enhance the potential use of PLA in single use plastics applications.
Combined Effects of Cellulose Nanofiber Nucleation and Maleated Polylactic Acid Compatibilization on the Crystallization Kinetic and Mechanical Properties of Polylactic Acid Nanocomposite

Shazleen SS, Foong Ng LY, Ibrahim NA, Hassan MA, Ariffin H

Polymers (Basel), 2021 Sep 23;13(19).
PMID: 34641040 DOI: 10.3390/polym13193226

This work investigated the combined effects of CNF nucleation (3 wt.%) and PLA-g-MA compatibilization at different loadings (1-4 wt.%) on the crystallization kinetics and mechanical properties of polylactic acid (PLA). A crystallization kinetics study was done through isothermal and non-isothermal crystallization kinetics using differential scanning calorimetry (DSC) analysis. It was shown that PLA-g-MA had some effect on nucleation as exhibited by the value of crystallization half time and crystallization rate of the PLA/PLA-g-MA, which were increased by 180% and 172%, respectively, as compared to neat PLA when isothermally melt crystallized at 100 °C. Nevertheless, the presence of PLA-g-MA in PLA/PLA-g-MA/CNF3 nanocomposites did not improve the crystallization rate compared to that of uncompatibilized PLA/CNF3. Tensile strength was reduced with the increased amount of PLA-g-MA. Contrarily, Young's modulus values showed drastic increment compared to the neat PLA, showing that the addition of the PLA-g-MA contributed to the rigidity of the PLA nanocomposites. Overall, it can be concluded that PLA/CNF nanocomposite has good performance, whereby the addition of PLA-g-MA in PLA/CNF may not be necessary for improving both the crystallization kinetics and tensile strength. The addition of PLA-g-MA may be needed to produce rigid nanocomposites; nevertheless, in this case, the crystallization rate of the material needs to be compromised.
Fulltext Characterization and Cellular Internalization of Spherical Cellulose Nanocrystals (CNC) into Normal and Cancerous Fibroblasts

Shazali NAH, Zaidi NE, Ariffin H, Abdullah LC, Ghaemi F, Abdullah JM, et al.

Materials (Basel), 2019 Oct 04;12(19).
PMID: 31590332 DOI: 10.3390/ma12193251

The aim was to isolate cellulose nanocrystals (CNC) from commercialized oil palm empty fruit bunch cellulose nanofibre (CNF) through sulphuric acid hydrolysis and explore its safeness as a potential nanocarrier. Successful extraction of CNC was confirmed through a field emission scanning electron microscope (FESEM) and attenuated total reflection Fourier transmission infrared (ATR-FTIR) spectrometry analysis. For subsequent cellular uptake study, the spherical CNC was covalently tagged with fluorescein isothiocyanate (FITC), resulting in negative charged FITC-CNC nanospheres with a dispersity (Ð) of 0.371. MTT assay revealed low degree cytotoxicity for both CNC and FITC-CNC against C6 rat glioma and NIH3T3 normal fibroblasts up to 50 µg/mL. FITC conjugation had no contribution to the particle's toxicity. Through confocal laser scanning microscope (CLSM), synthesized FITC-CNC manifested negligible cellular accumulation, indicating a poor non-selective adsorptive endocytosis into studied cells. Overall, an untargeted CNC-based nanosphere with less cytotoxicity that posed poor selectivity against normal and cancerous cells was successfully synthesized. It can be considered safe and suitable to be developed into targeted nanocarrier.
Fulltext Process Optimization of Ultra-High Molecular Weight Polyethylene/Cellulose Nanofiber Bionanocomposites in Triple Screw Kneading Extruder by Response Surface Methodology

Sharip NS, Ariffin H, Andou Y, Shirosaki Y, Bahrin EK, Jawaid M, et al.

Molecules, 2020 Sep 30;25(19).
PMID: 33008017 DOI: 10.3390/molecules25194498

Incorporation of nanocellulose could improve wear resistance of ultra-high molecular weight polyethylene (UHMWPE) for an artificial joint application. Yet, the extremely high melt viscosity of the polymer may constrict the mixing, leading to fillers agglomeration and poor mechanical properties. This study optimized the processing condition of UHMWPE/cellulose nanofiber (CNF) bionanocomposite fabrication in triple screw kneading extruder by using response surface methodology (RSM). The effect of the process parameters-temperature (150-190 °C), rotational speed (30-60 rpm), and mixing time (30-45 min)-on mechanical properties of the bionanocomposites was investigated. Homogenous filler distribution, as confirmed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, was obtained through the optimal processing condition of 150 °C, 60 rpm, and 45 min. The UHMWPE/CNF bionanocomposites exhibited improved mechanical properties in terms of Young's and flexural modulus by 11% and 19%, respectively, as compared to neat UHMWPE. An insignificant effect was observed when maleic anhydride-grafted-polyethylene (MAPE) was added as compatibilizer. The obtained results proved that homogenous compounding of high melt viscosity UHMWPE with CNF was feasible by optimizing the melt blending processing condition in triple screw kneading extruder, which resulted in improved stiffness, a contributing factor for wear resistance.
Fulltext Melt- vs. Non-Melt Blending of Complexly Processable Ultra-High Molecular Weight Polyethylene/Cellulose Nanofiber Bionanocomposite

Sharip NS, Ariffin H, Yasim-Anuar TAT, Andou Y, Shirosaki Y, Jawaid M, et al.

Polymers (Basel), 2021 Jan 27;13(3).
PMID: 33513876 DOI: 10.3390/polym13030404

The major hurdle in melt-processing of ultra-high molecular weight polyethylene (UHMWPE) nanocomposite lies on the high melt viscosity of the UHMWPE, which may contribute to poor dispersion and distribution of the nanofiller. In this study, UHMWPE/cellulose nanofiber (UHMWPE/CNF) bionanocomposites were prepared by two different blending methods: (i) melt blending at 150 °C in a triple screw kneading extruder, and (ii) non-melt blending by ethanol mixing at room temperature. Results showed that melt-processing of UHMWPE without CNF (MB-UHMWPE/0) exhibited an increment in yield strength and Young's modulus by 15% and 25%, respectively, compared to the Neat-UHMWPE. Tensile strength was however reduced by almost half. Ethanol mixed sample without CNF (EM-UHMWPE/0) on the other hand showed slight decrement in all mechanical properties tested. At 0.5% CNF inclusion, the mechanical properties of melt-blended bionanocomposites (MB-UHMWPE/0.5) were improved as compared to Neat-UHMWPE. It was also found that the yield strength, elongation at break, Young's modulus, toughness and crystallinity of MB-UHMWPE/0.5 were higher by 28%, 61%, 47%, 45% and 11%, respectively, as compared to the ethanol mixing sample (EM-UHMWPE/0.5). Despite the reduction in tensile strength of MB-UHMWPE/0.5, the value i.e., 28.4 ± 1.0 MPa surpassed the minimum requirement of standard specification for fabricated UHMWPE in surgical implant application. Overall, melt-blending processing is more suitable for the preparation of UHMWPE/CNF bionanocomposites as exhibited by their characteristics presented herein. A better mechanical interlocking between UHMWPE and CNF at high temperature mixing with kneading was evident through FE-SEM observation, explains the higher mechanical properties of MB-UHMWPE/0.5 as compared to EM-UHMWPE/0.5.
Fulltext Clinical features of Malaysian children hospitalized with community-acquired seasonal influenza

Sam IC, Abdul-Murad A, Karunakaran R, Rampal S, Chan YF, Nathan AM, et al.

Int J Infect Dis, 2010 Sep;14 Suppl 3:e36-40.
PMID: 20153233 DOI: 10.1016/j.ijid.2009.10.005

OBJECTIVES: The clinical impact of seasonal influenza is understudied in tropical countries. The aim of this study was to describe the clinical features and seasonal pattern of influenza in children hospitalized in Malaysia, and to identify predictors of severe disease.
METHODS: Children hospitalized with community-acquired, laboratory-confirmed influenza at a teaching hospital in Kuala Lumpur, Malaysia during 2002-2007 were identified retrospectively. Clinical data were collected, and predictors of severe disease were identified by multivariate logistic regression. All influenza cases from 1982 to 2007 were also analyzed for seasonal patterns.
RESULTS: A total of 132 children were included in the study, 48 (36.4%) of whom had underlying medical conditions. The mean age was 2.5 years and 116 (87.9%) were <5 years old. The most common presenting features were fever or history of fever, cough, rhinitis, vomiting, and pharyngitis. Severe influenza was seen in 16 patients (12.1%; nine previously healthy), including 12 (9.1%; eight previously healthy) requiring intensive care. There were three (2.3%) deaths. Severe disease was associated with age <12 months, female sex, and absence of rhinitis on admission. Influenza was seen year-round, with peaks in November-January and May-July.
CONCLUSIONS: Seasonal influenza has a considerable impact on children hospitalized in Malaysia, in both the healthy and those with underlying medical conditions.

Study site: University Malaya Medical Centre (UMMC)

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