Browse publications by year: 2021

  1. Fulltext Psychosocial Work Environment and Teachers' Psychological Well-Being: The Moderating Role of Job Control and Social Support
    Ibrahim RZAR, Zalam WZM, Foster B, Afrizal T, Johansyah MD, Saputra J, et al.
    Int J Environ Res Public Health, 2021 07 08;18(14).
    PMID: 34299757 DOI: 10.3390/ijerph18147308
    Nowadays, the issue of teachers' psychological well-being causes serious concern, especially in Malaysia. Many studies related to psychological well-being have focused on students rather than on the health and well-being of teachers. Thus, the current study investigated the determinants of psychological well-being (depression, anxiety and stress) from the psychosocial work environment (job control, job demands and social support), and examined the moderating role of job control and social support in the relationship between job demands and psychological well-being among teachers. The design of this study was quantitative research through a survey questionnaire. The sample consisted of 335 high school teachers (23.3%-male; 76.7%-female) who responded to measuring scales of job demands, job control, social support, depression, anxiety and stress, and socio-demographic profile. The data were analyzed using two statistical methods, namely descriptive and inferential statistics. The hierarchical linear regression model was used to analyze the data by assisting the statistical software, i.e., SPSS-23. The results showed that job demands, job control and social support significantly predicted teachers' psychological well-being. Furthermore, the effect of job demands on teachers' depression and anxiety was partially moderated by job control and social support. In conclusion, this study has successfully identified the significant predictors of teachers' psychological well-being and the role of job control and social support as a moderating variable to teachers' psychological well-being in Malaysia. The result provides insights and contributes to the literature of teachers' psychological well-being determinants and involves Malaysian respondents with a collectivistic eastern culture.
    MeSH terms: Female; Humans; Job Satisfaction; Male; Surveys and Questionnaires; Social Support; Stress, Psychological/epidemiology; Students; Workplace*; School Teachers*
  2. Fulltext Efficacy of Photobiomodulation in the Treatment of Cancer Chemotherapy-Induced Oral Mucositis: A Meta-Analysis with Trial Sequential Analysis
    Al-Rudayni AHM, Gopinath D, Maharajan MK, Veettil SK, Menon RK
    Int J Environ Res Public Health, 2021 Jul 12;18(14).
    PMID: 34299869 DOI: 10.3390/ijerph18147418
    Oral mucositis is a debilitating complication of chemotherapy, characterized by erythema, ulcers and oedema of the oral mucosa. This review aimed to evaluate the efficacy of Photobiomodulation in the treatment of oral mucositis using meta-analysis and trial sequential analysis, and also to assess the quality of the results by Grading of Recommendations, Assessment, Development and Evaluation (GRADE). A comprehensive search of three databases, including Embase, Medline and Central, was performed to identify randomized controlled trials studying the efficacy of Photobiomodulation in the treatment of cancer chemotherapy-induced oral mucositis. The primary outcome was reduction in the severity of oral mucositis. Secondary outcomes were pain relief, duration of oral mucositis and adverse effects. The meta-analysis was performed using the random-effects model, and random errors of the meta-analyses were detected by trial sequential analysis. A total of 6 randomized controlled trials with 398 participants were included in our analysis. Photobiomodulation significantly reduced the severity of oral mucositis when compared to sham radiation (RR 0.43, 95% CI 0.20 to 0.93; p < 0.05). Sensitivity analysis by excluding trials with high risk of bias reiterated the robustness of our results (RR 0.28, 95% CI 0.16 to 0.48). Trial sequential analysis illustrated that the evidence from the meta-analysis was conclusive. The result of the meta-analyses with trial sequential analysis illustrated that Photobiomodulation is an effective therapeutic intervention for the treatment of oral mucositis, and the evidence gathered can be considered conclusive with a moderate level of certainty according to GRADE. Further trials are recommended to standardize the laser parameters required for the optimal effect.
    MeSH terms: Humans; Mouth Mucosa; Randomized Controlled Trials as Topic; Pain Management
  3. Fulltext Candida Chorioamnionitis in Mothers with Gestational Diabetes Mellitus: A Report of Two Cases
    Shazniza Shaaya E, Halim SAA, Leong KW, Ku KBP, Lim PS, Tan GC, et al.
    Int J Environ Res Public Health, 2021 07 13;18(14).
    PMID: 34299901 DOI: 10.3390/ijerph18147450
    Background:Candida chorioamnionitis is rarely encountered, even though vulvovaginal candidiasis incidence is about 15%. Interestingly, it has characteristic gross and histological findings on the umbilical cord that are not to be missed. Case Report: We report two cases of Candida chorioamnionitis with presence of multiple yellowish and red spots of the surface of the umbilical cord. Microscopically, these consist of microabscesses with evidence of fungal yeasts and pseudohyphae. The yeasts and pseudohyphae were highlighted by periodic acid- Schiff and Grocott methenamine silver histochemical stains. Both cases were associated with a history of gestational diabetes mellitus. Discussion: Peripheral funisitis is a characteristic feature of Candida chorioamnionitis. It is associated with high risk of adverse perinatal and neonatal outcomes, such as preterm delivery, stillbirth and neonatal death. We recommend careful examination of the umbilical cord of mothers with gestational diabetes mellitus.
    MeSH terms: Candida; Chorioamnionitis*; Female; Gestational Age; Humans; Infant, Newborn; Mothers; Pregnancy; Diabetes, Gestational*
  4. Fulltext Facebook Reviews as a Supplemental Tool for Hospital Patient Satisfaction and Its Relationship with Hospital Accreditation in Malaysia
    A Rahim AI, Ibrahim MI, Musa KI, Chua SL
    Int J Environ Res Public Health, 2021 07 13;18(14).
    PMID: 34299905 DOI: 10.3390/ijerph18147454
    Patient satisfaction is one indicator used to assess the impact of accreditation on patient care. However, traditional patient satisfaction surveys have a few disadvantages, and some researchers have suggested that social media be used in their place. Social media usage is gaining popularity in healthcare organizations, but there is still a paucity of data to support it. The purpose of this study was to determine the association between online reviews and hospital patient satisfaction and the relationship between online reviews and hospital accreditation. We used a cross-sectional design with data acquired from the official Facebook pages of 48 Malaysian public hospitals, 25 of which are accredited. We collected all patient comments from Facebook reviews of those hospitals between 2018 and 2019. Spearman's correlation and logistic regression were used to evaluate the data. There was a significant and moderate correlation between hospital patient satisfaction and online reviews. Patient satisfaction was closely connected to urban location, tertiary hospital, and previous Facebook ratings. However, hospital accreditation was not found to be significantly associated with online reports of patient satisfaction. This groundbreaking study demonstrates how Facebook reviews can assist hospital administrators in monitoring their institutions' quality of care in real time.
    MeSH terms: Accreditation; Cross-Sectional Studies; Hospitals; Humans; Malaysia; Patient Satisfaction*; Social Media*
  5. Fulltext Economic Burden of Stroke Disease: A Systematic Review
    Rochmah TN, Rahmawati IT, Dahlui M, Budiarto W, Bilqis N
    Int J Environ Res Public Health, 2021 07 15;18(14).
    PMID: 34299999 DOI: 10.3390/ijerph18147552
    Globally, one of the main causes of non-communicable disease as a cause of death every year is stroke. The objective of this study was to analyze the burden in consequence of stroke. This research used a systematic review method. Furthermore, a search for articles was carried out in June-July 2020. Four databases were used to search articles from 2015 to 2020. Eligible studies were identified, analyzed, and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The inclusion criteria were prospective cost studies, retrospective cost studies, database analysis, mathematical models, surveys, and COI studies that assess burden of stroke in primary and referral healthcare (hospital-based). The results showed that from four databases, 9270 articles were obtained, and 13 articles were qualified. A total of 9270 articles had the identified search keywords, but only 13 articles met the set criteria for inclusion. The criteria for inclusion were stroke patients, the economic burden of stroke disease based on cost of illness method, which is approximately equal to USD 1809.51-325,108.84 (direct costs 86.2%, and indirect costs 13.8%). Those that used the health expenditure method did not present the total cost; instead, only either direct or indirect cost of health expenditure were reported. For most hospital admissions due to stroke, LOS (length of stay) was the dominant cost. The high economic burden to manage stroke justifies the promotion and preventive efforts by the policymakers and motivates the practice of healthy lifestyles by the people.
    MeSH terms: Humans; Prospective Studies; Retrospective Studies; Health Care Costs; Cost of Illness*
  6. Fulltext Clinical and Laboratory Features of JAK2 V617F, CALR, and MPL Mutations in Malaysian Patients with Classical Myeloproliferative Neoplasm (MPN)
    Zulkeflee RH, Zulkafli Z, Johan MF, Husin A, Islam MA, Hassan R
    Int J Environ Res Public Health, 2021 Jul 16;18(14).
    PMID: 34300032 DOI: 10.3390/ijerph18147582
    Mutations of JAK2V617F, CALR, and MPL genes confirm the diagnosis of myeloproliferative neoplasm (MPN). This study aims to determine the genetic profile of JAK2V617F, CALR exon 9 Type 1 (52 bp deletion) and Type 2 (5 bp insertion), and MPL W515 L/K genes among Malaysian patients and correlate these mutations with clinical and hematologic parameters in MPN. Mutations of JAK2V617F, CALR, and MPL were analyzed in 159 Malaysian patients using allele-specific polymerase chain reaction, including 76 polycythemia vera (PV), 41 essential thrombocythemia (ET), and 42 primary myelofibrosis (PMF) mutations, and the demographics of the patients were retrieved. The result showed that 73.6% JAK2V617F, 5.66% CALR, and 27.7% were triple-negative mutations. No MPL W515L/K mutation was detected. In ET and PMF, the predominance type was the CALR Type 1 mutation. In JAK2V617F mutant patients, serum LDH was significantly higher in PMF compared to PV and ET. PV has a higher risk of evolving to post PV myelofibrosis compared to ET. A thrombotic event at initial diagnosis of 40.9% was high compared to global incidence. Only one PMF patient had a CALR mutation that transformed to acute myeloid leukemia. JAK2V617F and CALR mutations play an important role in diagnostics. Hence, every patient suspected of having a myeloproliferative neoplasm should be screened for these mutations.
    MeSH terms: Humans; Laboratories; Malaysia; Mutation; Polycythemia Vera*; Calreticulin/genetics; Janus Kinase 2/genetics; Receptors, Thrombopoietin/genetics
  7. Fulltext LSTM Networks to Improve the Prediction of Harmful Algal Blooms in the West Coast of Sabah
    Yussof FN, Maan N, Md Reba MN
    Int J Environ Res Public Health, 2021 07 19;18(14).
    PMID: 34300100 DOI: 10.3390/ijerph18147650
    Harmful algal bloom (HAB) events have alarmed authorities of human health that have caused severe illness and fatalities, death of marine organisms, and massive fish killings. This work aimed to perform the long short-term memory (LSTM) method and convolution neural network (CNN) method to predict the HAB events in the West Coast of Sabah. The results showed that this method could be used to predict satellite time series data in which previous studies only used vector data. This paper also could identify and predict whether there is HAB occurrence in the region. A chlorophyll a concentration (Chl-a; mg/L) variable was used as an HAB indicator, where the data were obtained from MODIS and GEBCO bathymetry. The eight-day dataset interval was from January 2003 to December 2018. The results obtained showed that the LSTM model outperformed the CNN model in terms of accuracy using RMSE and the correlation coefficient r as the statistical criteria.
    MeSH terms: Animals; Humans; Malaysia; Neural Networks (Computer)*; Harmful Algal Bloom*
  8. Fulltext Effects of Group and Individual Culturally Adapted Cognitive Behavioral Therapy on Depression and Sexual Satisfaction among Perimenopausal Women
    Khoshbooii R, Hassan SA, Deylami N, Muhamad R, Engku Kamarudin EM, Alareqe NA
    Int J Environ Res Public Health, 2021 07 20;18(14).
    PMID: 34300161 DOI: 10.3390/ijerph18147711
    AIMS: Previous research has shown the efficacy of culturally adapted Cognitive Behavioral Therapy (CA-CBT) in reducing depression, yet its effect on increasing sexual satisfaction is not well documented. In this study, an embedded randomized controlled trial design was used to examine the effect of group and individual CA-CBT on depression and sexual satisfaction among perimenopausal women.

    METHOD: A total of 64 depressed Iranian perimenopausal women were randomly assigned to two formats of treatments; sixteen sessions of group CA-CBT and eight sessions of individual CA-CBT, as well as a waitlist control group. Depression and sexual satisfaction were measured using BDI-II and ENRICH, respectively, at T1 (pre-treatment), T2 (post-treatment) and T3 (follow-up).

    RESULTS: Repeated measures ANOVA indicated that the women who underwent both group and individual CA-CBT had effectively reduced depression and increased sexual satisfaction between pre-treatment and post-treatment, and it was sustained after six months of follow-ups with large effect sizes of significant differences (p < 0.001), but the control group did not.

    CONCLUSION: The results showed promising evidence for the efficacy of both treatment groups of CA-CBT for depression and sexual satisfaction among perimenopausal women. The population mental health burden among perimenopausal women may likely be reduced by propagating this effective treatment.

    MeSH terms: Female; Humans; Iran; Orgasm; Cognitive Therapy*; Treatment Outcome; Perimenopause
  9. Fulltext Intelligent Platform Based on Smart PPE for Safety in Workplaces
    Márquez-Sánchez S, Campero-Jurado I, Herrera-Santos J, Rodríguez S, Corchado JM
    Sensors (Basel), 2021 Jul 07;21(14).
    PMID: 34300392 DOI: 10.3390/s21144652
    It is estimated that we spend one-third of our lives at work. It is therefore vital to adapt traditional equipment and systems used in the working environment to the new technological paradigm so that the industry is connected and, at the same time, workers are as safe and protected as possible. Thanks to Smart Personal Protective Equipment (PPE) and wearable technologies, information about the workers and their environment can be extracted to reduce the rate of accidents and occupational illness, leading to a significant improvement. This article proposes an architecture that employs three pieces of PPE: a helmet, a bracelet and a belt, which process the collected information using artificial intelligence (AI) techniques through edge computing. The proposed system guarantees the workers' safety and integrity through the early prediction and notification of anomalies detected in their environment. Models such as convolutional neural networks, long short-term memory, Gaussian Models were joined by interpreting the information with a graph, where different heuristics were used to weight the outputs as a whole, where finally a support vector machine weighted the votes of the models with an area under the curve of 0.81.
    MeSH terms: Personal Protective Equipment*; Artificial Intelligence; Humans; Neural Networks (Computer); Workplace
  10. Fulltext Urban Vegetation Mapping from Aerial Imagery Using Explainable AI (XAI)
    Abdollahi A, Pradhan B
    Sensors (Basel), 2021 Jul 11;21(14).
    PMID: 34300478 DOI: 10.3390/s21144738
    Urban vegetation mapping is critical in many applications, i.e., preserving biodiversity, maintaining ecological balance, and minimizing the urban heat island effect. It is still challenging to extract accurate vegetation covers from aerial imagery using traditional classification approaches, because urban vegetation categories have complex spatial structures and similar spectral properties. Deep neural networks (DNNs) have shown a significant improvement in remote sensing image classification outcomes during the last few years. These methods are promising in this domain, yet unreliable for various reasons, such as the use of irrelevant descriptor features in the building of the models and lack of quality in the labeled image. Explainable AI (XAI) can help us gain insight into these limits and, as a result, adjust the training dataset and model as needed. Thus, in this work, we explain how an explanation model called Shapley additive explanations (SHAP) can be utilized for interpreting the output of the DNN model that is designed for classifying vegetation covers. We want to not only produce high-quality vegetation maps, but also rank the input parameters and select appropriate features for classification. Therefore, we test our method on vegetation mapping from aerial imagery based on spectral and textural features. Texture features can help overcome the limitations of poor spectral resolution in aerial imagery for vegetation mapping. The model was capable of obtaining an overall accuracy (OA) of 94.44% for vegetation cover mapping. The conclusions derived from SHAP plots demonstrate the high contribution of features, such as Hue, Brightness, GLCM_Dissimilarity, GLCM_Homogeneity, and GLCM_Mean to the output of the proposed model for vegetation mapping. Therefore, the study indicates that existing vegetation mapping strategies based only on spectral characteristics are insufficient to appropriately classify vegetation covers.
    MeSH terms: Cities; Hot Temperature*; Neural Networks (Computer)*
  11. Fulltext Optimally-Weighted Image-Pose Approach (OWIPA) for Distracted Driver Detection and Classification
    Koay HV, Chuah JH, Chow CO, Chang YL, Rudrusamy B
    Sensors (Basel), 2021 Jul 15;21(14).
    PMID: 34300577 DOI: 10.3390/s21144837
    Distracted driving is the prime factor of motor vehicle accidents. Current studies on distraction detection focus on improving distraction detection performance through various techniques, including convolutional neural networks (CNNs) and recurrent neural networks (RNNs). However, the research on detection of distracted drivers through pose estimation is scarce. This work introduces an ensemble of ResNets, which is named Optimally-weighted Image-Pose Approach (OWIPA), to classify the distraction through original and pose estimation images. The pose estimation images are generated from HRNet and ResNet. We use ResNet101 and ResNet50 to classify the original images and the pose estimation images, respectively. An optimum weight is determined through grid search method, and the predictions from both models are weighted through this parameter. The experimental results show that our proposed approach achieves 94.28% accuracy on AUC Distracted Driver Dataset.
    MeSH terms: Accidents, Traffic; Neural Networks (Computer)*; Distracted Driving*
  12. Fulltext Workplace Mental State Monitoring during VR-Based Training for Offshore Environment
    Abu Hasan R, Sulaiman S, Ashykin NN, Abdullah MN, Hafeez Y, Ali SSA
    Sensors (Basel), 2021 Jul 18;21(14).
    PMID: 34300624 DOI: 10.3390/s21144885
    Adults are constantly exposed to stressful conditions at their workplace, and this can lead to decreased job performance followed by detrimental clinical health problems. Advancement of sensor technologies has allowed the electroencephalography (EEG) devices to be portable and used in real-time to monitor mental health. However, real-time monitoring is not often practical in workplace environments with complex operations such as kindergarten, firefighting and offshore facilities. Integrating the EEG with virtual reality (VR) that emulates workplace conditions can be a tool to assess and monitor mental health of adults within their working environment. This paper evaluates the mental states induced when performing a stressful task in a VR-based offshore environment. The theta, alpha and beta frequency bands are analysed to assess changes in mental states due to physical discomfort, stress and concentration. During the VR trials, mental states of discomfort and disorientation are observed with the drop of theta activity, whilst the stress induced from the conditional tasks is reflected in the changes of low-alpha and high-beta activities. The deflection of frontal alpha asymmetry from negative to positive direction reflects the learning effects from emotion-focus to problem-solving strategies adopted to accomplish the VR task. This study highlights the need for an integrated VR-EEG system in workplace settings as a tool to monitor and assess mental health of working adults.
    MeSH terms: Electroencephalography; User-Computer Interface; Workplace
  13. Fulltext The Potentials of Egyptian and Indian Granites for Protection of Ionizing Radiation
    Elsafi M, Alrashedi MF, Sayyed MI, Al-Hamarneh IF, El-Nahal MA, El-Khatib M, et al.
    Materials (Basel), 2021 Jul 14;14(14).
    PMID: 34300846 DOI: 10.3390/ma14143928
    This paper aims to study the radiation shielding characteristics and buildup factor of some types of granite in Egypt. The mass attenuation coefficient (MAC) for three types of granite (gandola, white halayeb, and red aswani) was experimentally determined, and the experimental results were validated by XCOM software. The relative deviation between the two methods does not exceed 3% in all discussed granite samples, which means that MAC calculated through the experimental and XCOM are in suitable agreement. The effective atomic number (Zeff) varies from 13.64 to 10.69, 13.68 to 10.59, and 13.45 and 10.66 for gandola, white halayeb, and red aswani, respectively. As well as the equivalent atomic number (Zeq) was calculated in a wide range of energy to deduce the exposure (EBF) and energy absorption (EABF) buildup factors for the studied granite materials. The linear attenuation coefficient (LAC), half-value layer (HVL), mean free path (MFP) were calculated at each investigated energy and showed that the most effective shielding ability at high energy was red aswani, while at low energy, the shielding ability was nearly constant for studied granites. The present study forms the first endeavor to obtain the radiation shielding properties of the studied materials to be used in practical applications.
  14. Fulltext Finite Element Analysis of Cushioned Diabetic Footwear Using Ethylene Vinyl Acetate Polymer
    Ghazali MJ, Ren X, Rajabi A, Zamri WFHW, Mohd Mustafah N, Ni J
    Polymers (Basel), 2021 Jul 09;13(14).
    PMID: 34301018 DOI: 10.3390/polym13142261
    With the development of societies, diabetic foot ulcers have become one of the most common diseases requiring lower extremity amputation. The early treatment and prevention of diabetic foot ulcers can considerably reduce the possibility of amputation. Using footwear to redistribute and relieve plantar pressure is one of the important measures for the treatment and prevention of diabetic foot ulcers. Thus, the evaluation and prediction of the distribution of plantar pressure play an important role in designing footwears. Herein, the finite element method was used to study plantar pressure under two kinds of foot models, namely, the skeletal structure foot model and the whole foot model, to explore the influence of human bones on the pressure of the soles of the feet and obtain accurate foot pressure. Simulation results showed that under the two models, the plantar pressure and the pressure from the footwear with ethylene vinyl acetate were all reduced. The total deformation demonstrated a slight increase. These stresses are very useful as they enable the design of suitable orthotic footwear that reduces the amount of stress in individuals with diabetic foot ulcers.
  15. Fulltext Current State and Challenges of Natural Fibre-Reinforced Polymer Composites as Feeder in FDM-Based 3D Printing
    Rajendran Royan NR, Leong JS, Chan WN, Tan JR, Shamsuddin ZSB
    Polymers (Basel), 2021 Jul 13;13(14).
    PMID: 34301046 DOI: 10.3390/polym13142289
    As one of the fastest-growing additive manufacturing (AM) technologies, fused deposition modelling (FDM) shows great potential in printing natural fibre-reinforced composites (NFRC). However, several challenges, such as low mechanical properties and difficulty in printing, need to be overcome. Therefore, the effort to improve the NFRC for use in AM has been accelerating in recent years. This review attempts to summarise the current approaches of using NFRC as a feeder for AM. The effects of fibre treatments, composite preparation methods and addition of compatibilizer agents were analysed and discussed. Additionally, current methods of producing feeders from NFRCs were reviewed and discussed. Mechanical property of printed part was also dependent on the printing parameters, and thus the effects of printing temperature, layer height, infill and raster angle were discussed, and the best parameters reported by other researchers were identified. Following that, an overview of the mechanical properties of these composites as reported by various researchers was provided. Next, the use of optimisation techniques for NFRCs was discussed and analysed. Lastly, the review provided a critical discussion on the overall topic, identified all research gaps present in the use of NFRC for AM processes, and to overcome future challenges.
  16. Fulltext Methotrexate-Loaded Gelatin and Polyvinyl Alcohol (Gel/PVA) Hydrogel as a pH-Sensitive Matrix
    Akhlaq M, Azad AK, Ullah I, Nawaz A, Safdar M, Bhattacharya T, et al.
    Polymers (Basel), 2021 Jul 14;13(14).
    PMID: 34301057 DOI: 10.3390/polym13142300
    The aim was to formulate and evaluate Gel/PVA hydrogels as a pH-sensitive matrix to deliver methotrexate (MTX) to colon. The primed Gel/PVA hydrogels were subjected to evaluation for swelling behavior, diffusion coefficient, sol-gel characteristic and porosity using an acidic (pH 1.2) and phosphate buffer (PBS) (pH 6.8 & pH 7.4) media. Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) were performed to evaluate the chemical compatibility of the Gel/PVA hydrogel. The shape alteration and release of Gel/PVA hydrogel was conducted at pH 1.2, pH 6.8 and pH 7.4. The drug release kinetic mechanism was determined using various kinetic equations. The physicochemical evaluation tests and drug release profile results were found to be significant (p < 0.01). However, it was dependent on the polymers' concentration, the pH of the release media and the amount of the cross-linking agent. Hydrogels containing the maximum amount of gel showed a dynamic equilibrium of 10.09 ± 0.18 and drug release of 93.75 ± 0.13% at pH 1.2. The kinetic models showed the release of MTX from the Gel/PVA hydrogel was non-Fickian. The results confirmed that the newly formed Gel/PVA hydrogels are potential drug delivery systems for a controlled delivery of MTX to the colon.
  17. Fulltext Bionanocarbon Functional Material Characterisation and Enhancement Properties in Nonwoven Kenaf Fibre Nanocomposites
    Rizal S, Mistar EM, Rahman AA, H P S AK, Oyekanmi AA, Olaiya NG, et al.
    Polymers (Basel), 2021 Jul 14;13(14).
    PMID: 34301059 DOI: 10.3390/polym13142303
    Bionanocarbon as a properties enhancement material in fibre reinforced nanobiocomposite was investigated for sustainable material applications. Currently, an extensive study using the micro size of biocarbon as filler or reinforcement materials has been done. However, poor fibre-matrix interface results in poor mechanical, physical, and thermal properties of the composite. Hence in this study, the nanoparticle of biocarbon was synthesised and applied as a functional material and properties enhancement in composite material. The bionanocarbon was prepared from an oil palm shell, an agriculture waste precursor, via a single-step activation technique. The nanocarbon filler loading was varied from 0, 1, 3, and 5% as nanoparticle properties enhancement in nonwoven kenaf fibre reinforcement in vinyl ester composite using resin transfer moulding technique. The functional properties were evaluated using TEM, particle size, zeta potential, and energy dispersion X-ray (EDX) elemental analysis. While the composite properties enhancement was evaluated using physical, mechanical, morphological, thermal, and wettability properties. The result indicated excellent nanofiller enhancement of fibre-matrix bonding that significantly improved the physical, mechanical, and thermal properties of the bionanocomposite. The SEM morphology study confirmed the uniform dispersion of the nanoparticle enhanced the fibre-matrix interaction. In this present work, the functional properties of bionanocarbon from oil palm shells (oil palm industrial waste) was incorporated in nanaobiocomposite, which significantly enhance its properties. The optimum enhancement of the bionanocomposite functional properties was obtained at 3% bionanocarbon loading. The improvement can be attributed to homogeneity and improved interfacial interaction between nanoparticles, kenaf fibre, and matrix.
  18. Fulltext Effects of Recycled Fe2O3 Nanofiller on the Structural, Thermal, Mechanical, Dielectric, and Magnetic Properties of PTFE Matrix
    Khamis AM, Abbas Z, Azis RS, Mensah EE, Alhaji IA
    Polymers (Basel), 2021 Jul 16;13(14).
    PMID: 34301089 DOI: 10.3390/polym13142332
    The purpose of this study was to improve the dielectric, magnetic, and thermal properties of polytetrafluoroethylene (PTFE) composites using recycled Fe2O3 (rFe2O3) nanofiller. Hematite (Fe2O3) was recycled from mill scale waste and the particle size was reduced to 11.3 nm after 6 h of high-energy ball milling. Different compositions (5-25 wt %) of rFe2O3 nanoparticles were incorporated as a filler in the PTFE matrix through a hydraulic pressing and sintering method in order to fabricate rFe2O3-PTFE nanocomposites. The microstructure properties of rFe2O3 nanoparticles and the nanocomposites were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The thermal expansion coefficients (CTEs) of the PTFE matrix and nanocomposites were determined using a dilatometer apparatus. The complex permittivity and permeability were measured using rectangular waveguide connected to vector network analyzer (VNA) in the frequency range 8.2-12.4 GHz. The CTE of PTFE matrix decreased from 65.28×10-6/°C to 39.84×10-6/°C when the filler loading increased to 25 wt %. The real (ε') and imaginary (ε″) parts of permittivity increased with the rFe2O3 loading and reached maximum values of 3.1 and 0.23 at 8 GHz when the filler loading was increased from 5 to 25 wt %. A maximum complex permeability of 1.1-j0.07 was also achieved by 25 wt % nanocomposite at 10 GHz.
  19. Fulltext Thermal, Physical and Mechanical Properties of Poly(Butylene Succinate)/Kenaf Core Fibers Composites Reinforced with Esterified Lignin
    Saffian HA, Yamaguchi M, Ariffin H, Abdan K, Kassim NK, Lee SH, et al.
    Polymers (Basel), 2021 Jul 19;13(14).
    PMID: 34301116 DOI: 10.3390/polym13142359
    In this study, Kraft lignin was esterified with phthalic anhydride and was served as reinforcing filler for poly(butylene succinate) (PBS). Composites with different ratios of PBS, lignin (L), modified lignin (ML) and kenaf core fibers (KCF) were fabricated using a compounding method. The fabricated PBS composites and its counterparts were tested for thermal, physical and mechanical properties. Weight percent gain of 4.5% after lignin modification and the FTIR spectra has confirmed the occurrence of an esterification reaction. Better thermo-mechanical properties were observed in the PBS composites reinforced with modified lignin and KCF, as higher storage modulus and loss modulus were recorded using dynamic mechanical analysis. The density of the composites fabricated ranged from 1.26 to 1.43 g/cm3. Water absorption of the composites with the addition of modified lignin is higher than that of composites with unmodified lignin. Pure PBS exhibited the highest tensile strength of 18.62 MPa. Incorporation of lignin and KCF into PBS resulted in different extents of reduction in tensile strength (15.78 to 18.60 MPa). However, PBS composite reinforced with modified lignin exhibited better tensile and flexural strength compared to its unmodified lignin counterpart. PBS composite reinforced with 30 wt% ML and 20 wt% KCF had the highest Izod impact, as fibers could diverge the cracking propagation of the matrix. The thermal conductivity value of the composites ranged from 0.0903 to 0.0983 W/mK, showing great potential as a heat insulator.
  20. Fulltext Metal-Based Nanocomposite Materials for Efficient Photocatalytic Degradation of Phenanthrene from Aqueous Solutions
    Chauhan HA, Rafatullah M, Ahmed Ali K, Siddiqui MR, Khan MA, Alshareef SA
    Polymers (Basel), 2021 Jul 20;13(14).
    PMID: 34301131 DOI: 10.3390/polym13142374
    Polycyclic aromatic hydrocarbons (PAHs) are a class of naturally occurring chemicals resulting from the insufficient combustion of fossil fuels. Among the PAHs, phenanthrene is one of the most studied compounds in the marine ecosystems. The damaging effects of phenanthrene on the environment are increasing day by day globally. To lessen its effect on the environment, it is essential to remove phenanthrene from the water resources in particular and the environment in general through advanced treatment methods such as photocatalytic degradation with high-performance characteristics and low cost. Therefore, the combination of metals or amalgamation of bimetallic oxides as an efficient photocatalyst demonstrated its propitiousness for the degradation of phenanthrene from aqueous solutions. Here, we reviewed the different nanocomposite materials as a photocatalyst, the mechanism and reactions to the treatment of phenanthrene, as well as the influence of other variables on the rate of phenanthrene degradation.
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