Browse publications by year: 2023

  1. Majeed MA, Shafri HZM, Zulkafli Z, Wayayok A
    PMID: 36901139 DOI: 10.3390/ijerph20054130
    This research aims to predict dengue fever cases in Malaysia using machine learning techniques. A dataset consisting of weekly dengue cases at the state level in Malaysia from 2010 to 2016 was obtained from the Malaysia Open Data website and includes variables such as climate, geography, and demographics. Six different long short-term memory (LSTM) models were developed and compared for dengue prediction in Malaysia: LSTM, stacked LSTM (S-LSTM), LSTM with temporal attention (TA-LSTM), S-LSTM with temporal attention (STA-LSTM), LSTM with spatial attention (SA-LSTM), and S-LSTM with spatial attention (SSA-LSTM). The models were trained and evaluated on a dataset of monthly dengue cases in Malaysia from 2010 to 2016, with the task of predicting the number of dengue cases based on various climate, topographic, demographic, and land-use variables. The SSA-LSTM model, which used both stacked LSTM layers and spatial attention, performed the best, with an average root mean squared error (RMSE) of 3.17 across all lookback periods. When compared to three benchmark models (SVM, DT, ANN), the SSA-LSTM model had a significantly lower average RMSE. The SSA-LSTM model also performed well in different states in Malaysia, with RMSE values ranging from 2.91 to 4.55. When comparing temporal and spatial attention models, the spatial models generally performed better at predicting dengue cases. The SSA-LSTM model was also found to perform well at different prediction horizons, with the lowest RMSE at 4- and 5-month lookback periods. Overall, the results suggest that the SSA-LSTM model is effective at predicting dengue cases in Malaysia.
    MeSH terms: Machine Learning; Climate; Dengue*; Humans; Malaysia
  2. Tan KP, Ang JK, Koh EBY, Pang NTP, Mat Saher Z
    PMID: 36901243 DOI: 10.3390/ijerph20054232
    Caregivers of People with dementia (PwD) commonly experience burdens and other mental health issues, e.g., depression and anxiety. At present, there are limited studies that examine the relationships between caregiver psychological factors and caregiver burden, and depressive and anxiety symptoms. Therefore, this study's objectives were to examine the relationships between psychological flexibility and mindfulness in caregivers of PwD, and to determine the predictors of these three outcomes. This was a cross-sectional study conducted in the geriatric psychiatry clinic of Kuala Lumpur Hospital, Malaysia, and the sample (n = 82) was recruited via a universal sampling method over three months. The participants completed a questionnaire that consisted of the sociodemographics of the PwD and caregivers, illness characteristics of the PwD, Acceptance and Action Questionnaire-II (AAQ-II), Mindful Attention Awareness Scale (MAAS), Zarit Burden Interview Scale (ZBI), Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7). The results show that despite significant relationships between psychological flexibility and mindfulness and lower levels of caregiver burden, and depressive and anxiety symptoms (p < 0.01), only psychological inflexibility (p < 0.01) remained as a significant predictor of the three outcomes. Therefore, in conclusion, intervention programs that target the awareness of the caregiver's psychological inflexibility should be implemented to alleviate these adverse outcomes in dementia caregivers.
    MeSH terms: Aged; Anxiety/psychology; Cross-Sectional Studies; Humans; Caregivers/psychology; Cost of Illness; Mindfulness*
  3. Che Had NH, Alavi K, Md Akhir N, Muhammad Nur IR, Shuhaimi MSZ, Foong HF
    PMID: 36901256 DOI: 10.3390/ijerph20054243
    The phenomenon of ageing may contribute to the rise of the dependent population. Due to the obstacles and difficulties they confront, the elderly's mobility decreases significantly. The aim of this article is to identify factors associated with mobility barriers in older adults. The method employed is an examination of articles published between 2011 and 2022 to identify common themes in previous studies. Four search engines were being used, and 32 articles have been included. This study demonstrated that health is a major factor associated with decreased mobility. This review identified four types of barriers which are health, built environment, socio-economic background and social relation change. This review could help policy makers and gerontologist in identifying solutions to resolve the mobility issues in older people.
    MeSH terms: Aged; Aging*; Humans; Mobility Limitation*
  4. Sahril N, Chan YM, Chan YY, Ahmad NA, Kassim MSA, Shahein NA, et al.
    PMID: 36901351 DOI: 10.3390/ijerph20054342
    OBJECTIVE: This study aims to determine the prevalence of poor self-rated health (SRH) in Malaysia and its association with sociodemographic characteristics, lifestyle behavior, chronic diseases, depression, and functional limitations in activities of daily living (ADLs) among older persons.

    DESIGN: Cross-sectional. Setting, participants, and outcome measures: We used data from the National Health and Morbidity Survey 2018, a nationwide community-based study. This study was conducted using a two-stage stratified cluster sampling design. Older persons were defined as persons aged 60 years and above. SRH was assessed using the question "How do you rate your general health?" and the answers were "very good", "good", "moderate", "not good", and "very bad". SRH was then grouped into two categories; "Good" (very good and good) and "Poor" (moderate, not good, and very bad). Descriptive and logistic regression analyses were conducted using SPSS version 25.0.

    RESULTS: The prevalence of poor SRH among older persons was 32.6%. Poor SRH was significantly related to physical inactivity, depression, and limitations in activities of daily living (ADLs). Multiple logistic regression revealed that poor SRH was positively associated with those who had depression (aOR 2.92, 95% CI:2.01,4.24), limitations in ADLs (aOR 1.82, 95% CI: 1.31, 2.54), low individual income (aOR 1.66, 95% CI:1.22, 2.26), physical inactivity (aOR 1.40, 95% CI:1.08, 1.82), and hypertension (aOR 1.23, 95% CI:1.02, 1.49).

    CONCLUSIONS: Older persons with depression, limitations in ADLs, low income, physical inactivity, and hypertension were significantly associated with poor SRH. These findings provide information to aid health personnel and policymakers in the development and implementation of health promotion and disease prevention programs, as well as adequate evidence in planning different levels of care for the older population.

    MeSH terms: Activities of Daily Living*; Aged; Aged, 80 and over; Cross-Sectional Studies; Health Status*; Humans; Hypertension*; Malaysia/epidemiology; Surveys and Questionnaires; Self Report
  5. Wan Puteh SE, Mohd Ismail N, Md Isa Z, Ban AY
    PMID: 36901455 DOI: 10.3390/ijerph20054443
    Tobacco and nicotine derivatives uses are multiple in nature. These include conventional cigarettes (CCs), heated tobacco products (HTPs), and electronic cigarettes (ECs). This study aims to determine the practices, nicotine dependency profile, association with exhaled carbon monoxide (eCO) level, and pulmonary function (PF) among adult product users and non-smokers. This cross-sectional study involved smokers, nicotine users, and non-smokers from two public health facilities in Kuala Lumpur from December 2021 to April 2022. Data on socio-demography, smoking profile, nicotine dependency level, anthropometry, eCO monitor, and spirometer measurements were recorded. Out of 657 respondents, 52.1% were non-smokers, 48.3% were CC only smokers, poly-users (PUs) (27.3%), EC-only users (20.9%), and HTP-only users (3.5%). EC use was prevalent among the younger aged, tertiary educated, and females; HTP use was prevalent among those of an older age and CC users was common among lower educated males. The highest median eCO (in ppm) seen were as follows: in CC users only (13.00), PUs (7.00), EC users (2.00), HTP users (2.00), and the least was observed among non-smokers (1.00), which is significantly different across the groups (p <0.001). Comparison of practice between the different product users showed significant differences in age of product initiation (p <0.001, youngest in CC users in PUs), duration of product use (p <0.001, longest in exclusive CC users), cost per month (p <0.001, highest in exclusive HTP users) and attempt to quit product (p <0.001, CC use in PUs had the highest attempt to quit), while there is no significant difference in Fagerström score across the groups. Among EC users, 68.2% successfully switched from smoking CCs to ECs. The findings suggest that EC and HTP users are exhaling less CO. The use of these products in a targeted approach may manage nicotine addiction. Switching practice was higher among current EC users (from using CCs), hence emphasizing the need of switching encouragement and total nicotine abstinence later on. Lower eCO levels in the PU group, (as compared to CC-only users) and high quit attempt rate among in CC use in PUs may indicate attempt of PUs in reducing CC use through alternative modalities such as ECs and HTPs.
    MeSH terms: Adult; Aged; Carbon Monoxide; Cross-Sectional Studies; Female; Humans; Malaysia; Male; Nicotine; Suppuration; Tobacco Use Disorder*; Exhalation; Tobacco Products*; Electronic Cigarettes*
  6. Abdul Rashid MR, Syed Mohamad SN, Tajjudin AIA, Roslan N, Jaffar A, Mohideen FBS, et al.
    PMID: 36901486 DOI: 10.3390/ijerph20054476
    This study aimed to explore the socio-demographic characteristics, mental health status, and perceived causes of pandemic fatigue with COVID-19 pandemic fatigue among the general population of Malaysia. The data was collected online during the transition from the COVID-19 pandemic phase to the endemic phase in Malaysia from 1 to 30 April 2022. Sociodemographic data, Depression Anxiety Stress Scale-21 (DASS-21), perceived causes of pandemic fatigue, and the Fatigue Assessment Scale (FAS) were included in the survey. The chi-square test and a simple logistic regression analysis were used to identify predictors of pandemic fatigue. The completed survey (N = 775) included individuals aged 18 years or above [mean 31.98 (SD = 12.16)] from all states in Malaysia. Pandemic fatigue prevalence was 54.2%. Severe to extremely severe depression, anxiety, and stress symptoms were detected in 11.2%, 14.9%, and 9.1% of the participants, respectively. Younger age, non-Malay ethnicity, living alone, and higher income categories were significantly higher in the fatigued group. Higher DASS-21 scores on all domains were associated with higher FAS scores. Meanwhile, high scores for perceived tiredness from complying with the COVID-19 Standard Operating Procedure (SOP), perceived risk of infection from COVID-19, perceived hardship due to the pandemic, perceived public complacency during the pandemic, and perceived changes due to the pandemic were associated with a higher FAS score. This study provides valuable information for policymakers and mental health professionals worldwide on pandemic fatigue and its associated factors, including mental health status in Malaysia.
    MeSH terms: Anxiety/epidemiology; Cross-Sectional Studies; Depression/epidemiology; Fatigue/epidemiology; Health Status; Humans; Malaysia/epidemiology; Mental Health; Pandemics
  7. Ao X, Ong TS, Teh BH
    PMID: 36901536 DOI: 10.3390/ijerph20054528
    Environmental degradation and ecological devastation have become widespread global concerns in recent years as a result of the expansion of the international economy. China's rapid economic development has been accompanied by a sloppy economic growth model that has damaged the local ecological environment. The Chinese government intends to improve the ecological environment by the end of 2020 in an effort to direct and improve these environmental issues. The strictest environmental laws became effective in 2015. In light of this, this research uses panel data analysis to examine the environmental strategy and environmental governance of Chinese corporations. This article analyses 14,512 samples of listed mainland Chinese enterprises from 2015 to 2020. This research investigates the connection between Corporate Sustainability Development Strategy and Corporate Environmental Governance, as well as the moderating effect of Corporate Environmental Investments.
    MeSH terms: China; Conservation of Natural Resources*; Government; Investments; Organizations; Environmental Policy*
  8. Amsah N, Md Isa Z, Ahmad N, Abdul Manaf MR
    PMID: 36901588 DOI: 10.3390/ijerph20054577
    As the COVID-19 pandemic continues, healthcare services have been grossly overwhelmed by the pandemic. Due to this circumstance, routine care for individuals with type 2 diabetes mellitus (T2DM) has been temporarily disrupted. The purpose of this systematic review was to summarize the evidence regarding the impact of the COVID-19 pandemic on healthcare utilization among patients with T2DM. A systematic search was conducted in the Web of Science, Scopus, and PubMed databases. The process of identifying the final articles followed the PRISMA guidelines. The inclusion criteria were articles published between 2020 and 2022, written in English, and studies focusing on the research question. Any proceedings and books were excluded. A total of fourteen articles relevant to the research question were extracted. Following that, the included articles were critically appraised using the Mixed Method Appraisal Tool (MMAT) and the Joanna Briggs Institute Critical Appraisal Tool to assess the quality of the studies. The findings were further classified into three themes: reduced healthcare utilization among T2DM patients in routine healthcare services, a surge of telemedicine usage, and delay in the delivery of healthcare services. The key messages include demands for monitoring the long-term effects of the missed care and that better preparedness is crucial for any pandemic in the future. A tight diagnostic workup at the community level and regular follow-ups are crucial in managing the impact of the pandemic among T2DM patients. Telemedicine should be on the agenda of the health system to maintain and complement healthcare services. Future research is warranted to determine effective strategies to deal with the impact of the pandemic on healthcare utilization and delivery among T2DM patients. A clear policy is essential and should be established.
    MeSH terms: Delivery of Health Care; Diabetes Mellitus, Type 2*; Humans; Patient Acceptance of Health Care; Pandemics
  9. Bin Suliman MA, Hanis TM, Kamdi MKA, Ibrahim MI, Musa KI
    PMID: 36901652 DOI: 10.3390/ijerph20054642
    Many stroke survivors suffer with varying degrees of disability and require assistance. Family members commonly act as informal caregivers, caring for these stroke survivors and ensuring care adherence. However, many caregivers reported a poor quality of life and physical and psychological distress. Due to these issues, multiple studies have been conducted to understand the experience of caregivers, the outcomes of caregiving, and interventional studies among caregivers. This study aims to explore the intellectual landscape of studies on stroke caregivers using bibliometric analysis. Studies with "stroke" and "caregiver" terms in the title were extracted from the Web of Sciences (WOS) database. The resulting publications were analysed using the 'bibliometrix' package in R. There were 678 publications analysed, dating from 1989 to 2022. The USA has the highest number of publications (28.6%), followed by China (12.1%) and Canada (6.1%). The most productive institution, journal and author were The University of Toronto (9.5%), 'Topics in Stroke Rehabilitation' journal (5.8%) and Tamilyn Bakas (3.1%), respectively. Co-occurrences keywords analysis revealed mainstream research on stroke survivors, burden, quality of life, depression, care, and rehabilitation, reflecting the timeless hotspot in the field. This bibliometric analysis helps us understand the current state of stroke caregiver research and its recent developments. This study can be used to evaluate research policies and promote international cooperation.
    MeSH terms: Humans; Quality of Life; Bibliometrics; Caregivers/psychology; Stroke*; Stroke Rehabilitation*
  10. Huang CJ, Choo KB
    Int J Mol Sci, 2023 Feb 25;24(5).
    PMID: 36901978 DOI: 10.3390/ijms24054549
    Adipogenesis is an indispensable cellular process that involves preadipocyte differentiation into mature adipocyte. Dysregulated adipogenesis contributes to obesity, diabetes, vascular conditions and cancer-associated cachexia. This review aims to elucidate the mechanistic details on how circular RNA (circRNA) and microRNA (miRNA) modulate post-transcriptional expression of targeted mRNA and the impacted downstream signaling and biochemical pathways in adipogenesis. Twelve adipocyte circRNA profiling and comparative datasets from seven species are analyzed using bioinformatics tools and interrogations of public circRNA databases. Twenty-three circRNAs are identified in the literature that are common to two or more of the adipose tissue datasets in different species; these are novel circRNAs that have not been reported in the literature in relation to adipogenesis. Four complete circRNA-miRNA-mediated modulatory pathways are constructed via integration of experimentally validated circRNA-miRNA-mRNA interactions and the downstream signaling and biochemical pathways involved in preadipocyte differentiation via the PPARγ/C/EBPα gateway. Despite the diverse mode of modulation, bioinformatics analysis shows that the circRNA-miRNA-mRNA interacting seed sequences are conserved across species, supporting mandatory regulatory functions in adipogenesis. Understanding the diverse modes of post-transcriptional regulation of adipogenesis may contribute to the development of novel diagnostic and therapeutic strategies for adipogenesis-associated diseases and in improving meat quality in the livestock industries.
    MeSH terms: RNA, Messenger/genetics; Signal Transduction; Gene Expression Profiling; Adipogenesis; Gene Regulatory Networks
  11. Wong YP, Tan GC, Khong TY
    Int J Mol Sci, 2023 Feb 25;24(5).
    PMID: 36901979 DOI: 10.3390/ijms24054550
    The outbreak of the coronavirus disease 2019 (COVID-19) pandemic, caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in a global public health crisis, causing substantial concern especially to the pregnant population. Pregnant women infected with SARS-CoV-2 are at greater risk of devastating pregnancy complications such as premature delivery and stillbirth. Irrespective of the emerging reported cases of neonatal COVID-19, reassuringly, confirmatory evidence of vertical transmission is still lacking. The protective role of the placenta in limiting in utero spread of virus to the developing fetus is intriguing. The short- and long-term impact of maternal COVID-19 infection in the newborn remains an unresolved question. In this review, we explore the recent evidence of SARS-CoV-2 vertical transmission, cell-entry pathways, placental responses towards SARS-CoV-2 infection, and its potential effects on the offspring. We further discuss how the placenta serves as a defensive front against SARS-CoV-2 by exerting various cellular and molecular defense pathways. A better understanding of the placental barrier, immune defense, and modulation strategies involved in restricting transplacental transmission may provide valuable insights for future development of antiviral and immunomodulatory therapies to improve pregnancy outcomes.
    MeSH terms: Female; Humans; Infant, Newborn; Placenta; Pregnancy; Pregnancy Complications, Infectious*; Pregnancy Outcome; Infectious Disease Transmission, Vertical
  12. Zulkefli N, Che Zahari CNM, Sayuti NH, Kamarudin AA, Saad N, Hamezah HS, et al.
    Int J Mol Sci, 2023 Feb 27;24(5).
    PMID: 36902038 DOI: 10.3390/ijms24054607
    Wounds are considered to be a serious problem that affects the healthcare sector in many countries, primarily due to diabetes and obesity. Wounds become worse because of unhealthy lifestyles and habits. Wound healing is a complicated physiological process that is essential for restoring the epithelial barrier after an injury. Numerous studies have reported that flavonoids possess wound-healing properties due to their well-acclaimed anti-inflammatory, angiogenesis, re-epithelialization, and antioxidant effects. They have been shown to be able to act on the wound-healing process via expression of biomarkers respective to the pathways that mainly include Wnt/β-catenin, Hippo, Transforming Growth Factor-beta (TGF-β), Hedgehog, c-Jun N-Terminal Kinase (JNK), NF-E2-related factor 2/antioxidant responsive element (Nrf2/ARE), Nuclear Factor Kappa B (NF-κB), MAPK/ERK, Ras/Raf/MEK/ERK, phosphatidylinositol 3-kinase (PI3K)/Akt, Nitric oxide (NO) pathways, etc. Hence, we have compiled existing evidence on the manipulation of flavonoids towards achieving skin wound healing, together with current limitations and future perspectives in support of these polyphenolic compounds as safe wound-healing agents, in this review.
    MeSH terms: Flavonoids*; Wound Healing/physiology; Signal Transduction; NF-kappa B/metabolism
  13. Lin B, Ser HL, Wang L, Li J, Chan KG, Lee LH, et al.
    Int J Mol Sci, 2023 Feb 28;24(5).
    PMID: 36902078 DOI: 10.3390/ijms24054648
    Matrix metalloproteinase-12 (MMP12), or macrophage metalloelastase, plays important roles in extracellular matrix (ECM) component degradation. Recent reports show MMP12 has been implicated in the pathogenesis of periodontal diseases. To date, this review represents the latest comprehensive overview of MMP12 in various oral diseases, such as periodontitis, temporomandibular joint dysfunction (TMD), orthodontic tooth movement (OTM), and oral squamous cell carcinoma (OSCC). Furthermore, the current knowledge regarding the distribution of MMP12 in different tissues is also illustrated in this review. Studies have implicated the association of MMP12 expression with the pathogenesis of several representative oral diseases, including periodontitis, TMD, OSCC, OTM, and bone remodelling. Although there may be a potential role of MMP12 in oral diseases, the exact pathophysiological role of MMP12 remains to be elucidated. Understanding the cellular and molecular biology of MMP12 is essential, as MMP12 could be a potential target for developing therapeutic strategies targeting inflammatory and immunologically related oral diseases.
    MeSH terms: Carcinoma, Squamous Cell/enzymology; Humans; Periodontitis/pathology
  14. Kovanich D, Low TY, Zaccolo M
    Int J Mol Sci, 2023 Feb 28;24(5).
    PMID: 36902098 DOI: 10.3390/ijms24054667
    cAMP is a second messenger that regulates a myriad of cellular functions in response to multiple extracellular stimuli. New developments in the field have provided exciting insights into how cAMP utilizes compartmentalization to ensure specificity when the message conveyed to the cell by an extracellular stimulus is translated into the appropriate functional outcome. cAMP compartmentalization relies on the formation of local signaling domains where the subset of cAMP signaling effectors, regulators and targets involved in a specific cellular response cluster together. These domains are dynamic in nature and underpin the exacting spatiotemporal regulation of cAMP signaling. In this review, we focus on how the proteomics toolbox can be utilized to identify the molecular components of these domains and to define the dynamic cellular cAMP signaling landscape. From a therapeutic perspective, compiling data on compartmentalized cAMP signaling in physiological and pathological conditions will help define the signaling events underlying disease and may reveal domain-specific targets for the development of precision medicine interventions.
    MeSH terms: Cyclic AMP*; Second Messenger Systems; Signal Transduction/physiology; Proteomics*
  15. Zaidi SAS, Kwan CE, Mohan D, Harun S, Luthfi AAI, Sajab MS
    Materials (Basel), 2023 Feb 22;16(5).
    PMID: 36902909 DOI: 10.3390/ma16051793
    As additive manufacturing continues to evolve, there is ongoing discussion about ways to improve the layer-by-layer printing process and increase the mechanical strength of printed objects compared to those produced by traditional techniques such as injection molding. To achieve this, researchers are exploring ways of enhancing the interaction between the matrix and filler by introducing lignin in the 3D printing filament processing. In this work, research has been conducted on using biodegradable fillers of organosolv lignin, as a reinforcement for the filament layers in order to enhance interlayer adhesion by using a bench-top filament extruder. Briefly, it was found that organosolv lignin fillers have the potential to improve the properties of polylactic acid (PLA) filament for fused deposition modeling (FDM) 3D printing. By incorporating different formulations of lignin with PLA, it was found that using 3 to 5% lignin in the filament leads to an improvement in the Young's modulus and interlayer adhesion in 3D printing. However, an increment of up to 10% also results in a decrease in the composite tensile strength due to the lack of bonding between the lignin and PLA and the limited mixing capability of the small extruder.
  16. Hashim AN, Salleh MAAM, Ramli MM, Abdullah MMAB, Sandu AV, Vizureanu P, et al.
    Materials (Basel), 2023 Feb 24;16(5).
    PMID: 36902968 DOI: 10.3390/ma16051852
    This paper presents an assessment of the effect of isothermal annealing of Sn whisker growth behavior on the surface of Sn0.7Cu0.05Ni solder joints using the hot-dip soldering technique. Sn0.7Cu and Sn0.7Cu0.05Ni solder joints with a similar solder coating thickness was aged up to 600 h in room temperature and annealed under 50 °C and 105 °C conditions. Through the observations, the significant outcome was the suppressing effect of Sn0.7Cu0.05Ni on Sn whisker growth in terms of density and length reduction. The fast atomic diffusion of isothermal annealing consequently reduced the stress gradient of Sn whisker growth on the Sn0.7Cu0.05Ni solder joint. It was also established that the smaller (Cu,Ni)6Sn5 grain size and stability characteristic of hexagonal η-Cu6Sn5 considerably contribute to the residual stress diminished in the (Cu,Ni)6Sn5 IMC interfacial layer and are able to suppress the growth of Sn whiskers on the Sn0.7Cu0.05Ni solder joint. The findings of this study provide environmental acceptance with the aim of suppressing Sn whisker growth and upsurging the reliability of the Sn0.7Cu0.05Ni solder joint at the electronic-device-operation temperature.
  17. Amirzade-Iranaq MT, Omidi M, Bakhsheshi-Rad HR, Saberi A, Abazari S, Teymouri N, et al.
    Materials (Basel), 2023 Feb 25;16(5).
    PMID: 36903033 DOI: 10.3390/ma16051919
    This study attempts to synthesize MgZn/TiO2-MWCNTs composites with varying TiO2-MWCNT concentrations using mechanical alloying and a semi-powder metallurgy process coupled with spark plasma sintering. It also aims to investigate the mechanical, corrosion, and antibacterial properties of these composites. When compared to the MgZn composite, the microhardness and compressive strength of the MgZn/TiO2-MWCNTs composites were enhanced to 79 HV and 269 MPa, respectively. The results of cell culture and viability experiments revealed that incorporating TiO2-MWCNTs increased osteoblast proliferation and attachment and enhanced the biocompatibility of the TiO2-MWCNTs nanocomposite. It was observed that the corrosion resistance of the Mg-based composite was improved and the corrosion rate was reduced to about 2.1 mm/y with the addition of 10 wt% TiO2-1 wt% MWCNTs. In vitro testing for up to 14 days revealed a reduced degradation rate following the incorporation of TiO2-MWCNTs reinforcement into a MgZn matrix alloy. Antibacterial evaluations revealed that the composite had antibacterial activity, with an inhibition zone of 3.7 mm against Staphylococcus aureus. The MgZn/TiO2-MWCNTs composite structure has great potential for use in orthopedic fracture fixation devices.
  18. Mohammed AA, Nahazanan H, Nasir NAM, Huseien GF, Saad AH
    Materials (Basel), 2023 Feb 28;16(5).
    PMID: 36903132 DOI: 10.3390/ma16052020
    Calcium-based binders, such as ordinary Portland cement (OPC) and lime (CaO), are the most common artificial cementitious materials used worldwide for concrete and soil improvement. However, using cement and lime has become one of the main concerns for engineers because they negatively affect the environment and economy, prompting research into alternative materials. The energy consumption involved in producing cementitious materials is high, and the subsequent CO2 emissions account for 8% of the total CO2 emissions. In recent years, an investigation into cement concrete's sustainable and low-carbon characteristics has become the industry's focus, achieved by using supplementary cementitious materials. This paper aims to review the problems and challenges encountered when using cement and lime. Calcined clay (natural pozzolana) has been used as a possible supplement or partial substitute to produce low-carbon cement or lime from 2012-2022. These materials can improve the concrete mixture's performance, durability, and sustainability. Calcined clay has been utilized widely in concrete mixtures because it produces a low-carbon cement-based material. Owing to the large amount of calcined clay used, the clinker content of cement can be lowered by as much as 50% compared with traditional OPC. It helps conserve the limestone resources used in cement manufacture and helps reduce the carbon footprint associated with the cement industry. Its application is gradually growing in places such as Latin America and South Asia.
  19. Nasarudin NA, Razali M, Goh V, Chai WL, Muchtar A
    Materials (Basel), 2023 Mar 01;16(5).
    PMID: 36903142 DOI: 10.3390/ma16052027
    Over the years, advancement in ceramic-based dental restorative materials has led to the development of monolithic zirconia with increased translucency. The monolithic zirconia fabricated from nano-sized zirconia powders is shown to be superior in physical properties and more translucent for anterior dental restorations. Most in vitro studies on monolithic zirconia have focused mainly on the effect of surface treatment or the wear of the material, while the nanotoxicity of this material is yet to be explored. Hence, this research aimed to assess the biocompatibility of yttria-stabilized nanozirconia (3-YZP) on the three-dimensional oral mucosal models (3D-OMM). The 3D-OMMs were constructed using human gingival fibroblast (HGF) and immortalized human oral keratinocyte cell line (OKF6/TERT-2), co-cultured on an acellular dermal matrix. On day 12, the tissue models were exposed to 3-YZP (test) and inCoris TZI (IC) (reference material). The growth media were collected at 24 and 48 h of exposure to materials and assessed for IL-1β released. The 3D-OMMs were fixed with 10% formalin for the histopathological assessments. The concentration of the IL-1β was not statistically different between the two materials for 24 and 48 h of exposure (p = 0.892). Histologically, stratification of epithelial cells was formed without evidence of cytotoxic damage and the epithelial thickness measured was the same for all model tissues. The excellent biocompatibility of nanozirconia, as evidenced by the multiple endpoint analyses of the 3D-OMM, may indicate the potential of its clinical application as a restorative material.
  20. Abdul Razak NE, Dee CF, Madhuku M, Ahmad I, Chang EY, Yu HW, et al.
    Materials (Basel), 2023 Mar 02;16(5).
    PMID: 36903185 DOI: 10.3390/ma16052070
    The super enhancement of silicon band edge luminescence when co-implanted with boron and carbon is reported. The role of boron in the band edge emissions in silicon was investigated by deliberately introducing defects into the lattice structures. We aimed to increase the light emission intensity from silicon by boron implantation, leading to the formation of dislocation loops between the lattice structures. The silicon samples were doped with a high concentration of carbon before boron implantation and then annealed at a high temperature to activate the dopants into substitutional lattice sites. Photoluminescence (PL) measurements were performed to observe the emissions at the near-infrared region. The temperatures were varied from 10 K to 100 K to study the effect of temperature on the peak luminescence intensity. Two main peaks could be seen at ~1112 and 1170 nm by observing the PL spectra. The intensities shown by both peaks in the samples incorporated with boron are significantly higher than those in pristine silicon samples, and the highest intensity in the former was 600 times greater than that in the latter. Transmission electron microscopy (TEM) was used to study the structure of post-implant and post-anneal silicon sample. The dislocation loops were observed in the sample. Through a technique compatible with mature silicon processing technology, the results of this study will greatly contribute to the development of all Si-based photonic systems and quantum technologies.
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