Showing papers by "Universiti Sains Malaysia published in 2018"

Insight into Cellular Uptake and Intracellular Trafficking of Nanoparticles.

Abstract: Nanoparticle science is rapidly changing the landscape of various scientific fields and defining new technological platforms. This is perhaps even more evident in the field of nanomedicine whereby nanoparticles have been used as a tool for the treatment and diagnosis of many diseases. However, despite the tremendous benefit conferred, common pitfalls of this technology is its potential short and long-term effects on the human body. To understand these issues, many scientific studies have been carried out. This review attempts to shed light on some of these studies and its outcomes. The topics that were examined in this review include the different possible uptake pathways of nanoparticles and intracellular trafficking routes. Additionally, the effect of physicochemical properties of nanoparticle such as size, shape, charge and surface chemistry in determining the mechanism of uptake and biological function of nanoparticles are also addressed.

Hybrid clustering analysis using improved krill herd algorithm

Abstract: In this paper, a novel text clustering method, improved krill herd algorithm with a hybrid function, called MMKHA, is proposed as an efficient clustering way to obtain promising and precise results in this domain. Krill herd is a new swarm-based optimization algorithm that imitates the behavior of a group of live krill. The potential of this algorithm is high because it performs better than other optimization methods; it balances the process of exploration and exploitation by complementing the strength of local nearby searching and global wide-range searching. Text clustering is the process of grouping significant amounts of text documents into coherent clusters in which documents in the same cluster are relevant. For the purpose of the experiments, six versions are thoroughly investigated to determine the best version for solving the text clustering. Eight benchmark text datasets are used for the evaluation process available at the Laboratory of Computational Intelligence (LABIC). Seven evaluation measures are utilized to validate the proposed algorithms, namely, ASDC, accuracy, precision, recall, F-measure, purity, and entropy. The proposed algorithms are compared with the other successful algorithms published in the literature. The results proved that the proposed improved krill herd algorithm with hybrid function achieved almost all the best results for all datasets in comparison with the other comparative algorithms.

5-Hydroxymethylfurfural (HMF) levels in honey and other food products: effects on bees and human health

Abstract: An organic compound known as 5-hydroxymethylfurfural (HMF) is formed from reducing sugars in honey and various processed foods in acidic environments when they are heated through the Maillard reaction. In addition to processing, storage conditions affect the formation HMF, and HMF has become a suitable indicator of honey quality. HMF is easily absorbed from food through the gastrointestinal tract and, upon being metabolized into different derivatives, is excreted via urine. In addition to exerting detrimental effects (mutagenic, genotoxic, organotoxic and enzyme inhibitory), HMF, which is converted to a non-excretable, genotoxic compound called 5-sulfoxymethylfurfural, is beneficial to human health by providing antioxidative, anti-allergic, anti-inflammatory, anti-hypoxic, anti-sickling, and anti-hyperuricemic effects. Therefore, HMF is a neo-forming contaminant that draws great attention from scientists. This review compiles updated information regarding HMF formation, detection procedures, mitigation strategies and effects of HMF on honey bees and human health.

General Pathways of Pain Sensation and the Major Neurotransmitters Involved in Pain Regulation

Abstract: Pain has been considered as a concept of sensation that we feel as a reaction to the stimulus of our surrounding, putting us in harm’s way and acting as a form of defense mechanism that our body has permanently installed into its system. However, pain leads to a huge chunk of finances within the healthcare system with continuous rehabilitation of patients with adverse pain sensations, which might reduce not only their quality of life but also their productivity at work setting back the pace of our economy. It may not look like a huge deal but factor in pain as an issue for majority of us, it becomes an economical burden. Although pain has been researched into and understood by numerous researches, from its definition, mechanism of action to its inhibition in hopes of finding an absolute solution for victims of pain, the pathways of pain sensation, neurotransmitters involved in producing such a sensation are not comprehensively reviewed. Therefore, this review article aims to put in place a thorough understanding of major pain conditions that we experience—nociceptive, inflammatory and physiologically dysfunction, such as neuropathic pain and its modulation and feedback systems. Moreover, the complete mechanism of conduction is compiled within this article, elucidating understandings from various researches and breakthroughs.

The prehistoric peopling of Southeast Asia.

Abstract: The human occupation history of Southeast Asia (SEA) remains heavily debated Current evidence suggests that SEA was occupied by Hoabinhian hunter-gatherers until ~4000 years ago, when farming economies developed and expanded, restricting foraging groups to remote habitats Some argue that agricultural development was indigenous; others favor the "two-layer" hypothesis that posits a southward expansion of farmers giving rise to present-day Southeast Asian genetic diversity By sequencing 26 ancient human genomes (25 from SEA, 1 Japanese Jōmon), we show that neither interpretation fits the complexity of Southeast Asian history: Both Hoabinhian hunter-gatherers and East Asian farmers contributed to current Southeast Asian diversity, with further migrations affecting island SEA and Vietnam Our results help resolve one of the long-standing controversies in Southeast Asian prehistory

Bootstrapping the autoregressive distributed lag test for cointegration

Abstract: We propose a bootstrap autoregressive-distributed lag (ARDL) test. By applying the appropriate bootstrap method, some weaknesses underlying the Pesaran, Shin and Smith ARDL bounds test are addresse...

Working Memory From the Psychological and Neurosciences Perspectives: A Review.

Abstract: Since the concept of working memory was introduced over 50 years ago, different schools of thought have offered different definitions for working memory based on the various cognitive domains that it encompasses. The general consensus regarding working memory supports the idea that working memory is extensively involved in goal-directed behaviors in which information must be retained and manipulated to ensure successful task execution. Before the emergence of other competing models, the concept of working memory was described by the multicomponent working memory model proposed by Baddeley and Hitch. In the present article, the authors provide an overview of several working memory-relevant studies in order to harmonize the findings of working memory from the neurosciences and psychological standpoints, especially after citing evidence from past studies of healthy, aging, diseased, and/or lesioned brains. In particular, the theoretical framework behind working memory, in which the related domains that are considered to play a part in different frameworks (such as memory’s capacity limit and temporary storage) are presented and discussed. From the neuroscience perspective, it has been established that working memory activates the fronto-parietal brain regions, including the prefrontal, cingulate, and parietal cortices. Recent studies have subsequently implicated the roles of subcortical regions (such as the midbrain and cerebellum) in working memory. Aging also appears to have modulatory effects on working memory; age interactions with emotion, caffeine and hormones appear to affect working memory performances at the neurobiological level. Moreover, working memory deficits are apparent in older individuals, who are susceptible to cognitive deterioration. Another younger population with working memory impairment consists of those with mental, developmental, and/or neurological disorders such as major depressive disorder and others. A less coherent and organized neural pattern has been consistently reported in these disadvantaged groups. Working memory of patients with traumatic brain injury was similarly affected and shown to have unusual neural activity (hyper- or hypoactivation) as a general observation. Decoding the underlying neural mechanisms of working memory helps support the current theoretical understandings concerning working memory, and at the same time provides insights into rehabilitation programs that target working memory impairments from neurophysiological or psychological aspects.

Essential Oils: Extraction Techniques, Pharmaceutical And Therapeutic Potential - A Review.

Abstract: Background Essential oils are liquid extracts from aromatic plants, which have numerous applications in multiple industries. There are a variety of methods used for the extraction of essential oils, with each method exhibiting certain advantages and determining the biological and physicochemical properties of the extracted oils. Essential oils from different plant species contain more than 200 constituents which are comprised of volatile and non-volatile components. The application of essential oils as antimicrobial, anticancer, anti-inflammatory and anti-viral agents is due to their effective and efficient properties, inter alia. Method Several advanced (supercritical fluid extraction, subcritical extraction liquid, solvent-free microwave extraction) and conventional (hydrodistillation, steam distillation, hydrodiffusion, solvent extraction) methods have been discussed for the extraction of essential oils. Advanced methods are considered as the most promising extraction techniques due to less extraction time, low energy consumption, low solvent used and less carbon dioxide emission. Conclusion This manuscript reviewed the major research studies in the field and discussed several research findings on the chemical composition of essential oils, methods of oil extraction, and application of these oils in pharmaceutical and therapeutic fields. These essential oils can be used as anticancer, antimicrobial, antiviral, and as skin permeation enhancer agents.

E-learning continuance satisfaction in higher education: a unified perspective from instructors and students

Abstract: This study aims to determine the key factors affecting students’ and instructors’ continuance satisfaction with e-learning in the higher education context. In order to identify the factors that impact e-learning continuation in higher education institutions, a systematic review of the literature was conducted, revealing that the majority of studies have reported the essential role of satisfaction in mediating the relationship between 11 factors and users’ decisions to continue using e-learning systems. This study then proposed that users, both students and instructors, must continually be satisfied with the e-learning systems offered by higher education institutions if they are to continue using them. We term this ‘e-learning continuance satisfaction.’ The formation of a unified perspective of instructors and students on the core factors that impact e-learning continuance was then investigated, in addition to the causal relationships between these factors and e-learning continuance satisfaction. T...

A systematic review of cloud computing tools for collaborative learning: Opportunities and challenges to the blended-learning environment

Abstract: The use of online collaborative learning activities has been notably supported by cloud computing. Although specific reference has been made to a certain online application or service, there has been no clear understanding of how different cloud computing tools have shaped the concept of collaborative learning, and the extent to which these resources are accessible to today's students. Thus, a review of the literature was conducted to identify studies on cloud computing tools for collaborative learning in a blended classroom. The review of the literature led to the inclusion of 29 relevant studies categorized as synchronized tools, Learning Management System (LMS) tools, and social networking tools. The review results revealed a set of evidences supporting the use of certain cloud computing tools for certain collaborative learning activities categorized under sharing, editing, communication and discussion. The key opportunities and challenges associated with the use of these tools in a blended learning context were also identified and discussed. Findings from this study will certainly help academicians, practitioners and researchers to understand the potential of using cloud computing environments from a wider perspective.

Synthesis of biomass as heterogeneous catalyst for application in biodiesel production: State of the art and fundamental review

Abstract: Biodiesel is gaining attention as a remedy for the increasing demand of fossil fuels which is depleting rapidly. Commercial homogeneous catalysts in the biodiesel production industry are facing challenges such as separation difficulties and severe corrosion which will lead to the increment of production and maintenance cost. Herein, this paper focuses on the comprehensive review of literature reported on the usage of biomass as the precursor for the catalyst used in biodiesel production. Compared to other commercial catalysts, the usage of biomass as catalyst precursor possesses several advantages such as abundantly available, cheaper raw materials, reusable, non-toxic and biodegradable. Carbon material synthesized from biomass which acts as the efficient support for active sites due to its high porosity and surface area characteristic has been studied widely. The latest development of biomass derived basic, acidic and magnetic heterogeneous catalyst through several state of the art synthesis pathways starting from the synthesis of the supporting material (carbon) until the functionalization process to form the complete catalyst was reviewed. Apart from direct sulfonation using sulfuric acid, sulfonation by reduction and arylation were less hazardous and provided comparable active sites activity. Most biomass based catalysts exhibited good catalytic performance by providing high biodiesel yield of above 80% at optimum conditions. Besides that, various kinetic models developed from the reaction kinetic study catalyzed by biomass based catalyst were also reviewed as a preparatory stage for the scaled-up commercialization process of the studied catalyst in the biodiesel production sector. This catalyst could assist to lower the activation energy required for the reactions and thus enables higher reaction rate to reach equilibrium. Continuous research on producing high performing biomass based catalyst with minimum resources is needed in order to achieve the ultimate goal of green and sustainable biodiesel industry.

Implications of insecticide resistance for malaria vector control with long-lasting insecticidal nets: a WHO-coordinated, prospective, international, observational cohort study

Abstract: Summary Background Scale-up of insecticide-based interventions has averted more than 500 million malaria cases since 2000. Increasing insecticide resistance could herald a rebound in disease and mortality. We aimed to investigate whether insecticide resistance was associated with loss of effectiveness of long-lasting insecticidal nets and increased malaria disease burden. Methods This WHO-coordinated, prospective, observational cohort study was done at 279 clusters (villages or groups of villages in which phenotypic resistance was measurable) in Benin, Cameroon, India, Kenya, and Sudan. Pyrethroid long-lasting insecticidal nets were the principal form of malaria vector control in all study areas; in Sudan this approach was supplemented by indoor residual spraying. Cohorts of children from randomly selected households in each cluster were recruited and followed up by community health workers to measure incidence of clinical malaria and prevalence of infection. Mosquitoes were assessed for susceptibility to pyrethroids using the standard WHO bioassay test. Country-specific results were combined using meta-analysis. Findings Between June 2, 2012, and Nov 4, 2016, 40 000 children were enrolled and assessed for clinical incidence during 1·4 million follow-up visits. 80 000 mosquitoes were assessed for insecticide resistance. Long-lasting insecticidal net users had lower infection prevalence (adjusted odds ratio [OR] 0·63, 95% CI 0·51–0·78) and disease incidence (adjusted rate ratio [RR] 0·62, 0·41–0·94) than did non-users across a range of resistance levels. We found no evidence of an association between insecticide resistance and infection prevalence (adjusted OR 0·86, 0·70–1·06) or incidence (adjusted RR 0·89, 0·72–1·10). Users of nets, although significantly better protected than non-users, were nevertheless subject to high malaria infection risk (ranging from an average incidence in net users of 0·023, [95% CI 0·016–0·033] per person-year in India, to 0·80 [0·65–0·97] per person year in Kenya; and an average infection prevalence in net users of 0·8% [0·5–1·3] in India to an average infection prevalence of 50·8% [43·4–58·2] in Benin). Interpretation Irrespective of resistance, populations in malaria endemic areas should continue to use long-lasting insecticidal nets to reduce their risk of infection. As nets provide only partial protection, the development of additional vector control tools should be prioritised to reduce the unacceptably high malaria burden. Funding Bill & Melinda Gates Foundation, UK Medical Research Council, and UK Department for International Development.

Honey as a Potential Natural Antioxidant Medicine: An Insight into Its Molecular Mechanisms of Action.

Abstract: Honey clasps several medicinal and health effects as a natural food supplement. It has been established as a potential therapeutic antioxidant agent for various biodiverse ailments. Data report that it exhibits strong wound healing, antibacterial, anti-inflammatory, antifungal, antiviral, and antidiabetic effects. It also retains immunomodulatory, estrogenic regulatory, antimutagenic, anticancer, and numerous other vigor effects. Data also show that honey, as a conventional therapy, might be a novel antioxidant to abate many of the diseases directly or indirectly associated with oxidative stress. In this review, these wholesome effects have been thoroughly reviewed to underscore the mode of action of honey exploring various possible mechanisms. Evidence-based research intends that honey acts through a modulatory road of multiple signaling pathways and molecular targets. This road contemplates through various pathways such as induction of caspases in apoptosis; stimulation of TNF-α, IL-1β, IFN-γ, IFNGR1, and p53; inhibition of cell proliferation and cell cycle arrest; inhibition of lipoprotein oxidation, IL-1, IL-10, COX-2, and LOXs; and modulation of other diverse targets. The review highlights the research done as well as the apertures to be investigated. The literature suggests that honey administered alone or as adjuvant therapy might be a potential natural antioxidant medicinal agent warranting further experimental and clinical research.

Advances in solar photovoltaic tracking systems: A review

Abstract: Solar photovoltaic technology is one of the most important resources of renewable energy. However, the current solar photovoltaic systems have significant drawbacks, such as high costs compared to fossil fuel energy resources, low efficiency, and intermittency. Capturing maximum energy from the sun by using photovoltaic systems is challenging. Several factors that affect the energy output of such systems include the photovoltaic material, geographical location of solar irradiances, ambient temperature and weather, angle of sun incidence, and orientation of the panel. This study reviews the principles and mechanisms of photovoltaic tracking systems to determine the best panel orientation. The tracking techniques, efficiency, performance, advantages, and disadvantages of simple tracking systems are compared with those of state-of-the-art tracking systems. Diverse types of solar tracking systems based on their technologies and driving methods will be presented and categorized.The future trends of tracking systems are also highlighted.

Insights into the thermolytic transformation of lignocellulosic biomass waste to redox-active carbocatalyst: Durability of surface active sites

Abstract: The thermolytic transformation of lignocellulosic spent coffee grounds to superior redox-active carbocatalyst (denoted as NBC) via nitrogen functionalization in a pyrolytic environment at various temperatures was investigated. The intrinsic (e.g. surface chemistry, degree of graphitization, etc.) and extrinsic (e.g. specific surface area, morphology, etc.) properties of the catalysts were systematically studied using various characterization techniques. The three main N configurations conducive to redox reactions, namely pyrrolic N, pyridinic N and graphitic N were present at different compositions in all the NBCs prepared at pyrolysis temperature ≥500 °C. The NBCs were used as peroxymonosulfate (PMS) activator for degrading bisphenol A. It was found that NBC-1000 (prepared at 1000 °C) has the highest catalytic performance (kapp = 0.072 min−1) due to the relatively higher specific surface area (438 m2 g−1), excellent degree of graphitization, and optimum N bonding configuration ratio. Based on the radical scavenger and electron paramagnetic resonance studies, the nonradical pathway involving 1O2 generation is identified as the prevailing pathway while the radical pathway involving SO4 −and OH generation is the recessive pathway. Further investigation of the durability of surface active sites revealed that the active sites undergo N bonding configuration reconstruction and cannibalistic oxidation (increase in surface oxygen content) during PMS activation reaction. The graphitic N manifest greater catalytic activity and stability compared to pyridinic N and pyrrolic N under oxidizing environment. The results demonstrated that reaction optimization is critical to improve the durability of the catalyst. This study provides useful insights in converting lignocellulosic biomass waste into functional catalytic material, and the strategy to improve the durability of carbocatalysts for redox-based reactions.

Sustainable product design and development: A review of tools, applications and research prospects

Abstract: Due to increasing pressure for achieving sustainability objectives, the concept of sustainable product design and development is gaining more attention in recent research. In the past, a plethora of eco-design tools that address only the environmental aspect have been developed. Hence, previous review articles focused mainly on eco-design tools, such as life cycle assessment (LCA) and others. Unlike previous studies, the main contribution of this article was to review and analyze the recent and emerging product design tools (published from 2007 to 2017) which considered other dimensions of sustainability along with the environment. Based on the criteria of sustainability dimensions, this paper proposed a generic and broader classification scheme to enhance the understanding of these recent tools. Those which included two aspects of sustainability were categorized as partial sustainable product design (P-SPD) tools, and those which covered three aspects of sustainability were classified as sustainable product design (SPD) tools. The analysis revealed that SPD tools were less mature and standard as compared to P-SPD tools. The majority of both P-SPD and SPD tools were based on a life cycle perspective. However, P-SPD tools were found to be more useful at early design stages. In addition, this paper presented the case studies of the tools to decipher their practical utility. It also discussed the hurdles and problems associated with the methodological development and practical utility of the tools. Founded on these difficulties, future research directions were presented. In essence, a coordinated and responsible effort among practitioners, governments, societies and researchers is needed to ensure the successful implementation of the tools.

Mediation analysis issues and recommendations

Abstract: This editorial outlines and responds to some of the most frequently asked questions regarding mediation analysis. Specifically, six key issues are addressed with reference to the state-of-the-art mediation literature. In doing this, we provide practical guidelines for researchers to successfully conceptualise, test and interpret mediation models. Recent references are also provided to discourage researchers from using outdated mediation approaches in their theses/manuscripts. It is our hope that this effort will clarify misconceptions regarding mediation analysis and provide up-to-date guidelines for researchers to make informed decisions and conduct the analysis appropriately.