The 50 most-cited articles in Heliyon, 2019

In the present review, we have been able to describe the different families of dyes and pigments used in textile finishing processes (Yarns, fabrics, nonwovens, knits and rugs) such as dyeing and printing. These dyes are reactive, direct, dispersed, indigo, sulphur and vats. Such that their presence in the liquid effluents resulting from the textile washing constitutes a serious risk, in the absence of their purification, for the quality of receiving aquatic environments. Indeed, the presence of these dyes and pigments can cause a significant alteration in the ecological conditions of the aquatic fauna and flora, because of the lack of their biodegradability. This has a negative impact on the equilibrium of the aquatic environment by causing serious dangers, namely the obvious dangers (Eutrophication, under-oxygenation, color, turbidity and odor), the long-term dangers (Persistence, bioaccumulation of carcinogenic aromatic products and formation of by-products of chlorination), mutagenicity and carcinogenicity.

The purpose of this study is to develop new knowledge to better understand the most important dimensions of e-service quality that have impact on customer satisfaction, customer trust, and customer behavior, building on existing literature on e-service quality in online shopping. This study focuses on the four-dimensions of e-service quality model that better predict customer behavior. It not only tests the impact of customer satisfaction on customer behavior such as repurchase intention, word of mouth, and site revisit, but also the impact of customer trust. The result is expected to extend the knowledge about different country culture vis-á-vis different relevance of e-service quality attributes. Data from an online survey of 355 Indonesian online consumers was used to test the research model using structural equation modelling. The analytical results showed that three dimensions of e-service quality, namely website design, security/privacy and fulfilment affect overall e-service quality. Meanwhile, customer service is not significantly related to overall e-service quality.…

Urban green spaces are considered an appropriate way to reduce urban heat island effects and provide comfort to the nearby occupants. In addition to cooling the actual space, urban green spaces are also able to influence the surrounding area, and this phenomenon is called the urban green space cooling effect. The most important issues with regard to the cooling effects of urban green spaces are the intensity and density of the cooling, which can play a major role for urban designers and planners in dealing with urban heat island. This article reviews the latest studies that have examined the cooling effects of urban green spaces in recent years. Based on the method of evaluation of their samples, the studies are divided into three groups. The first category consists of research into a set of urban green spaces in one part of or in an entire city, mainly conducted through remote sensing and satellite maps. The second category investigates city parks or several urban parks with recognizable shapes and locations. In this section, information was mainly gathered by virtue of field…

Bangladesh - one of the most densely populated countries of the world- has plentiful water sources, but these sources are being polluted continuously. Both surface water and groundwater sources are contaminated with different contaminants like toxic trace metals, coliforms as well as other organic and inorganic pollutants. As most of the population uses these water sources, especially groundwater sources which contain an elevated amount of arsenic throughout the country; health risk regarding consuming water is very high. Death due to water-borne diseases is widespread in Bangladesh, particularly among children. Anthropogenic sources such as untreated industrial effluents, improper disposal of domestic waste, agricultural runoffs are the main contributors regarding water pollution. A total water pollution status of this country, as well as the sources of this severe condition, is crucial to evaluate public health risk. For this purpose, we reviewed hundreds of well recognized international and national journals, conference proceedings and other related documents to draw a complete…

The upsurge in the volume of unwanted emails called spam has created an intense need for the development of more dependable and robust antispam filters. Machine learning methods of recent are being used to successfully detect and filter spam emails. We present a systematic review of some of the popular machine learning based email spam filtering approaches. Our review covers survey of the important concepts, attempts, efficiency, and the research trend in spam filtering. The preliminary discussion in the study background examines the applications of machine learning techniques to the email spam filtering process of the leading internet service providers (ISPs) like Gmail, Yahoo and Outlook emails spam filters. Discussion on general email spam filtering process, and the various efforts by different researchers in combating spam through the use machine learning techniques was done. Our review compares the strengths and drawbacks of existing machine learning approaches and the open research problems in spam filtering. We recommended deep leaning and deep adversarial learning as the…

BACKGROUND: In response to various environmental stresses, many plant species synthesize L-proline in the cytosol and accumulates in the chloroplasts. L-Proline accumulation in plants is a well-recognized physiological reaction to osmotic stress prompted by salinity, drought and other abiotic stresses. L-Proline plays several protective functions such as osmoprotectant, stabilizing cellular structures, enzymes, and scavenging reactive oxygen species (ROS), and keeps up redox balance in adverse situations. In addition, ample-studied osmoprotective capacity, L-proline has been also ensnared in the regulation of plant improvement, including flowering, pollen, embryo, and leaf enlargement. SCOPE AND CONCLUSIONS: Albeit, ample is now well-known about L-proline metabolism, but certain characteristics of its biological roles are still indistinct. In the present review, we discuss the L-proline accumulation, metabolism, signaling, transport and regulation in the plants. We also discuss the effects of exogenous L-proline during different environmental conditions. L-Proline biosynthesis and…

Waste materials from natural sources are important resources for extraction and recovery of valuable compounds. Transformation of these waste materials into valuable materials requires specific techniques and approaches. Hydroxyapatite (HAp) is a biomaterial that can be extracted from natural wastes. HAp has been widely used in biomedical applications owing to its excellent bioactivity, high biocompatibility, and excellent osteoconduction characteristics. Thus, HAp is gaining prominence for applications as orthopaedic implants and dental materials. This review summarizes some of the recent methods for extraction of HAp from natural sources including mammalian, aquatic or marine sources, shell sources, plants and algae, and from mineral sources. The extraction methods used to obtain hydroxyapatite are also described. The effect of extraction process and natural waste source on the critical properties of the HAp such as Ca/P ratio, crystallinity and phase assemblage, particle sizes, and morphology are discussed herein.

BACKGROUND: Biofilms are multicellular communities of microorganisms held together by a self-produced extracellular matrix. The ability of microbes to form biofilm is a universal, ubiquitous, and dynamic process. This dynamic process of biofilms establishes an important strategy to withstand and survive harsh environmental conditions and antimicrobial agents. OBJECTIVE: This review paper aims to give an overview of antibiotic resistance, intervention, and treatment of infections caused by biofilm-forming organisms. Moreover, it can also help to motivate scholars to search for new anti-biofilm strategies and most appropriate methods to tackle the effect of biofilm infections on healthcare services. METHODS: This paper was written by reviewing recent research and review articles which are reporting about the antibiotic resistance, prevention, and treatment of biofilm-producing organisms. CONCLUSION: Bioprospecting for quorum quenching compounds can be an appropriate solution for controlling biofilm infections.

Several economic, institutional, technical and socio-cultural barriers hinder countries from moving from the high to the low emission pathway. The objective of this research is to find out the impacts of social, economic, technological and regulatory barriers in the deployment of renewable energy. Data were collected through an online questionnaire responded to by 223 professionals working in the energy sector all over the globe. This research shows that social, technological and regulatory barriers have a strong influence on the deployment of renewable energy, while economic barriers significantly influence it indirectly. By breaking research and development-related barriers, organizations will be able to invest greatly in developing advanced technologies that can optimize usage of renewable energy and make renewable energy appear more lucrative. With less polluting and lower tariff energy solutions being made available to local people, and higher profits for manufacturers, this will create an atmosphere where all stakeholders are satisfied.

Campylobacter species are among the leading cause of bacterial foodborne and waterborne infections. In addition, Campylobacter is one of the major causative agent of bacterial gastrointestinal infections and the rise in the incidence of Campylobacter infections have been reported worldwide. Also, the emergence of some Campylobacter species as one of the main causative agent of diarrhea and the propensity of these bacteria species to resist the actions of antimicrobial agents; position them as a serious threat to the public health. This paper reviews Campylobacter pathogenicity, infections, isolation and diagnosis, their reservoirs, transmission pathways, epidemiology of Campylobacter outbreaks, prevention and treatment option, antibiotics resistance and control of antibiotics use.

Tinospora cordifolia is a popular medicinal plant which is used in several traditional medicines to cure various diseases. The common names are Amrita and Guduchi and belong to the family of Menispermaceae. It is considered an essential herbal plant of Indian system of medicine (ISM) and has been used in the treatment of fever, urinary problem, dysentery, skin diseases leprosy, diabetes, and many more diseases. The plant reported containing chemical compound including Alkaloids, Terpenoids, Lignans, Steroids and others that establish the phytochemistry and pharmacological activity of Tinospora cordifolia . The present review highlights the pharmacological importance viz antioxidant activity, antimicrobial activity, antibacterial activity, antifungal activity, anti-diabetic activity, antistress activity, hypolipidaemic effect, hepatic disorder, anticancer anti HIV potential, antiosteoporotic effects, antitoxic effects, wound healing, anticomplementary activity, and immunomodulating activity, systemic infection and Parkinson ̓s disease.

Quantifying the emissions of per- and polyfluoroalkyl substances (PFAS) from Australian wastewater treatment plants (WWTP) is of high importance due to potential impacts on receiving aquatic ecosystems. The new Australian PFAS National Environmental Management Plan recommends 0.23 ng L −1 of PFOS as the guideline value for 99% species protection for aquatic systems. In this study, 21 PFAS from four classes were measured in WWTP solid and aqueous samples from 19 Australian WWTPs. The mean ∑ 21 PFAS was 110 ng L −1 (median: 80 ng L −1 ; range: 9.3–520 ng L −1 ) in aqueous samples and 34 ng g −1 dw (median: 12 ng g −1 dw; range: 2.0–130 ng g −1 dw) in WWTP solids. Similar to WWTPs worldwide, perfluorocarboxylic acids were generally higher in effluent, compared to influent. Partitioning to solids within WWTPs increased with increasing fluoroalkyl chain length from 0.05 to 1.22 log units. Many PFAS were highly correlated, and PCA analysis showed strong associations between two groups: odd chained PFCAs, PFHxA and PFSAs; and 6:2 FTS with daily inflow volume and the proportion of trade…

Driven by the rapid uptake of battery electric vehicles, Li-ion power batteries are increasingly reused in stationary energy storage systems, and eventually recycled to recover all the valued components. Offering an updated global perspective, this study provides a circular economy insight on lithium-ion battery reuse and recycling.

Herbs and spices come from different parts of the plant are used to impart an aroma and taste to food. Several herbs have therapeutic properties such as antioxidative, anti-inflammatory, antidiabetic, antihypertensive and antimicrobial activities. Therefore, fortification of dairy foods with herbs and spices could help to provide functional dairy products with nutritional and medicinal values. Also, herbs and spices are used to improve the appearance and attractiveness of fortified foods for consumers and to increase the sale of those herbs. Therefore, only the highest quality herbs or spices can be added to dairy products to combat contaminating microorganisms. In this review the latest progresses in the dairy sector concerning the addition of numerous herbs and spices in different forms (i.e. powder, fresh, extract, essential oils) to dairy food has been conversed. Also, the effects of those herbs and spices on the quality of dairy products such as yoghurts, cheeses, butter, gee and ice creams have been presented.

Chitosan, a natural carbohydrate polymer, has long been investigated for drug delivery and medical applications due to its biodegradability, biocompatibility and low toxicity. The micro/nanoparticulate forms of chitosan are reported to enhance the efficiency of drug delivery with better physicochemical properties including improved solubility and bioavailability. This polymer is known to be biodegradable and biocompatible; however, crosslinked chitosan particles may not be biodegradable. Crosslinkers (e.g., tripolyphosphate and glutaraldehyde) are needed for efficient micro/nanoparticle formation, but it is not clear whether the resultant particles are biodegradable or able to release the encapsulated drug fully. To date, no studies have conclusively demonstrated the complete biodegradation or elimination of chitosan nanoparticles in vivo . Herein we review the synthesis and degradation mechanisms of chitosan micro/nanoparticles frequently used in drug delivery especially in pulmonary drug delivery to understand whether these nanoparticles are biodegradable.

Cereals like wheat, rice, corn, barley, rye, oat, and millet are staple foods in many regions around the world and contribute to more than half of human energy requirements. Scientific publications contain evidence showing that apart from energy, the regular consumption of whole grains is useful for the prevention of many chronic diseases associated with oxidative stress. Biological activities have mostly been attributed to the presence of glucans and polyphenols. In recent years however, food proteins have been investigated as sources of peptides that can exert biological functions, promote health and prevent oxidative stress. This review focuses on the role of hydrolyzed proteins and peptides with antioxidant properties in various models and their mechanisms which include hydrogen or electron transfer, metal chelating, and regulation of enzymes involved in the oxidation-reduction process.

An automated method to determine the band gap energy ( E g ) of pure and mixed powder compounds using diffuse reflectance spectroscopy is presented. This method is based on a five-step algorithm that mimics the judgment made by an expert analyst in identifying the linear segments in Tauc plots and subsequent estimation of the E g value. It is demonstrated that the method to estimate E g by intersecting the straight-line fit of the Tauc segment with the photon energy axis is not appropriate for those samples containing more than one optical absorbing phase because systematic underestimation of the E g value results. The automated method accounts for such cases by introducing a base line function. The robustness of the implemented algorithm was tested using three model systems, ZnO-Al 2 O 3 , ZnO-CoO and ZnO-CdO. The estimated E g 's using the automated method differ in less than 1% than those obtained by its manual counterpart.

Plastic is an amazing material, and wonderful invention, it has changed the world. Plastic is used everywhere and every day across the globe. But despite its varied uses, its disposal has threatened the environment. Biodegradable plastics can meet these needs and can easily be disposed to the environment. This work focuses on the characterization and performance analysis of starch bioplastics and composite bioplastic to reduce the plastic pollution by its various uses. TGA, DSC, SEM, FTIR, and surface roughness analyses were used to characterize, the mechanical properties, thermal properties and the morphology of the starch bioplastics and composite bioplastic. Starch bioplastics were fabricated using starch vinegar and glycerol. Composite bioplastics ware fabricated using starch, vinegar, glycerol and titanium dioxide. The addition of titanium dioxide improved the tensile strength of the bioplastics from 3.55 to 3.95 MPa and decreased elongation from 88% to 62%. According to Differential Scanning Calorimetry (DSC) Test, the melting point (T m ) and Glass Transition Temperature (T g…

The cruise tourism industry has experienced significant growth in recent years and has a very positive outlook for the future. However, its environmental impact requires a review of its sustainability, including the analysis of its social, economic and environmental balance, and the evaluation of its impact on port cities receiving cruise ships. The purpose of this document is twofold: First, to analyze the relationship between air quality, as an environmental variable, and the volume of cruise ships and passengers that visit a port with the aim of generating information. Secondly, it is intended to develop an index, based on the information already available that allows cities to predict the impact of this activity, so that decisions are made to alleviate these effects. Methods: The primary data taken monthly for the period 2006-2017, related to the level of emissions and the number of cruises and passengers, are used as a basis. A regression analysis is performed to determine the relationship between air pollution and the number of tourists coming from the cruise ships. As a…

fruit extract as a novel natural resource. The synthesized particles were polyhedral (mostly hexagonal) in shape between 14 - 48 nm with an average size of 24.75 ± 0.78 nm. Nano zinc oxide (ZnO) at concentrations of 2% (w/w) and 4% (w/w), were incorporated into agar matrix. Solution casting method was used to fabricate the bionanocomposite films with ZnONPs in agar. Surface morphology, particle size, crystallinity, thermal stability and functional groups were determined using SEM, TEM, XRD, TGA and FTIR, respectively. Loading of ZnONPs in composite films improved thermal stability, elongation and film thickness, whereas tensile strength and transparency decreased. The films were used for packaging of green grapes, and appearance of the fruit was observed during ambient storage. Grapes packaged in composite films showed fresh appearance up to 14 and 21 days in ambient conditions for 2% (w/w) and 4% (w/w) ZnONPs in films, respectively. The results showed the potential of the fabricated agar-ZnO nanocomposite film as a promising packaging material to enhance postharvest shelf-life of…

This work investigates the effects of combined variable viscosity and thermal conductivity, nonlinear radiation and non-Darcian porous medium on a boundary layer MHD Casson nanofluid flow over a vertical flat plate with convective heating and velocity slip boundary conditions. The governing transport nonlinear partial differential equations and the boundary conditions are non-dimensionalized. The resulting system of coupled partial differential equations is then reduced to a set of coupled nonlinear ordinary differential equations using similarity transformation. Galerkin weighted residual method (GWRM) is then employed to solve the resulting set of equations. Numerical results are obtained for dimensionless velocity, temperature and nanoparticle volume fraction (nanoparticle concentration). It is found that the velocity increases, while both temperature and nanoparticle volume fraction decrease with increased values of variable thermal conductivity and viscosity. Comparisons are carried out with published data in the literature thereby validating the numerical results. An excellent…

The central highlands of Ethiopia are characterized as a region of high rates of land degradation and soil erosion. This study aimed to estimate total amount of soil loss and sediment yield using RUSLE model within GIS environment. LULC maps of 1973-2015 were used to evaluate the impact of land use change on soil loss and sediment yield. Each model parameter and sediment deliver ration was computed by using Williams and Berndt empirical equation. The net soil erosion and sediment yield at the Guder river mouth and soil risk map was estimated for the watershed. LULC dynamic for the study period and watershed have shown that there existed a rapid conversion of vegetated land uses to human modified land uses. The study revealed that the mean soil loss from the watershed ranges between 25 and 30 t/ha-1 yr-1 which accounted 25.8, 28.7 and 30.3 t/ha/yr for 1973, 1995 and 2015 periods respectively. The estimated total soil loss in 1973, 1995 and 2015 periods were 198Mt yr-1, 221Mt yr-1 and 239Mt yr-1 respectively. The mean sediment yield estimated was 6.79, 8.65 and 9.44t ha-1 yr-1 for…

Pectin, a natural polysaccharide, has gained increasing attention due to not only its biomaterial properties but also its biomedical activities. One of the abundant sources of pectin is mangosteen ( Garcinia mangostana L.) rind. In this study, we characterized the pectin from Indonesian mangosteen rind extract and evaluated its antioxidant activity. Pectin was extracted in acid condition and evaluated its physicochemical properties by fourier transform infrared (FTIR), powder X-ray diffractometer (PXRD), water content, ash content, equivalent weight, methoxyl level and of galacturonic acid content. Furthermore, the antioxidant activity of pectin was also observed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Pectin was successfully extracted from dry weight of Indonesian mangosten rind with yield about 1,16 ± 0,17%, fine powder, brownish and odorless. FTIR and PXRD results showed that pectin from mangosteen rind extract was amorphous and similar characteristic with a commercial pectin. The chemical properties of pectin such as water content, ash content, equivalent weight,…

In this ever-progressive digital era, conventional e-learning methods have become inadequate to handle the requirements of upgraded learning processes especially in the higher education. E-learning adopting Cloud computing is able to transform e-learning into a flexible, shareable, content-reusable, and scalable learning methodology. Despite plentiful Cloud e-learning frameworks have been proposed across literature, limited researches have been conducted to study the usability factors predicting continuance intention to use Cloud e-learning applications. In this study, five usability factors namely Computer Self Efficacy (CSE), Enjoyment (E), Perceived Ease of Use (PEU), Perceived Usefulness (PU), and User Perception (UP) have been identified for factor analysis. All the five independent variables were hypothesized to be positively associated to a dependent variable namely Continuance Intention (CI). A survey was conducted on 170 IT students in one of the private universities in Malaysia. The students were given one trimester to experience the usability of Cloud e-Learning…

The present work is focused on spectroscopic study of four samples of Argan wooden artifact pertaining to the 17 th , 18 th , 20 th and 21 st centuries. The objective is to characterize their unknown structures by the study of their non degraded parts and to investigate changes occurred in their degraded parts due to the natural degradation process. Attenuated total reflectance Fourier transform infrared spectroscopy gauges the presence of many functional groups related to cellulose I and/or II (OH, C–O–C and –CH 2 ), hemicelluloses (particularly C=O acetoxy ester band at 1732 cm −1 ), and lignin (OH phenolic, C ar -O and C=C ar ) and provides qualitative information on the state of wood alteration by informing on the evolution of new former C=O bands. The degree of conversion to carbonyl group, especially quinone or p- quinone at 1650 cm −1 , is correlated to lignin degradation, while the absence of the C=O acetoxy absorption is ascribable to occurred deterioration in hemicelluloses, and partial degradation of cellulose with enhancement of the C=O region between 1730-1630 cm −1 .…

In this study, the antimicrobial and scaffold of zinc-substituted hydroxyapatite, (Zn-HAp) synthesized via chemical co-precipitation technique was investigated. The structure of the synthesized Zn-HAp was investigated with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Scanning electron microscope (SEM), Energy dispersive X-spectroscopy (EDAX), transmission electron microscope (TEM), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Bioactivity study was performed in simulated body fluid (SBF), while the antimicrobial activity was studied using disc diffusion method. The XRD structure revealed that Zn ion incorporation up to 10% led to the second phase hydroxyapatite (HAp) formation, while higher concentration diminished the apatite structure. The presence of phosphate ions, carbonates ions, and hydroxyl groups in the apatite powder was ascertained by the FT-IR evaluation. SEM evaluation showed that the apatite contains fine particles with nearly round shape with interconnected pores and decreasing Ca/P ratio with increasing Zn…

Effluent discharges from industry and domestic waste containing unknown inorganic pollutants. In this work, different mechanisms of heavy metal ions removal using ZnO particles were studied. ZnO particles were synthesized using solid precipitation technique. The morphology of ZnO particles was rod-like shape. The average length and diameter of ZnO particle were 497.34 ± 15.55 and 75.78 ± 10.39nm, respectively. These particles removed effectively heavy metal ions such as Cu(II), Ag(I) and Pb(II) ions with efficiency >85% under exposure of 1 hour of UV light. However, poor removal efficiency, i.e. <15% was observed for Cr(VI), Mn(II), Cd(II) and Ni(II) ions. The removal of these heavy metal ions was in the forms of metals or metal oxide via reduction/oxidation or adsorption mechanism.

Novel silver nanoparticles from Gleichenia Pectinata ( Willd.) C. Presl. was synthesized. A combination of spectroscopic and microscopic techniques were utilized to characterize the newly synthesized Gleichenia Pectinata Silver Nanoparticles (GPAgNPs) vis-à-vis UV-Vis Spectroscopy, Fourier Transform Infra-Red (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-Ray Diffraction (XRD) Analyses. Significant absorption was observed at 460 nm resulting from the surface Plasmon resonance (SPR). A rapid rate of synthesis was observed and the best surface plasmon resonance was obtained at 105 minutes contact time. SEM and TEM showed an spherical shape of GPAgNPs with an average size of 7.51 nm. The XRD result revealed a crystalline and polydispersed GPAgNPs. GPAgNPs were effective against four antibiotic resistant pathogens and they exhibited excellent antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli , Klebsiella pneumoniae and Candida albicans. GPAgNPs favorably competed with…

Since early times, the people of Morocco use medicinal and aromatic plants as traditional medicine to heal different human ailments. However, little studies have been made in the past to properly document and promote the traditional knowledge. This study was carried out in the Rif (North of Morocco), it aimed to identify medicinal and aromatic plant used by the local people to treat metabolic diseases, together with the associated ethnomedicinal knowledge. The ethnomedical information collected was from 582 traditional healers using semi-structured interviews, free listing and focus group. Family use value (FUV), use value (UV), plant part value (PPV), fidelity level (FL) and informant agreement ratio (IAR) were employed in data analysis. Medicinal and aromatic plant were collected, identified and kept at the natural resources and biodiversity laboratory, Ibn Tofail University, Kenitra. During the present study 30 medicinal plant species belonging to 14 families has been documented. The most frequent ailments reported were diabetes (IAR = 0.98). The majority of the remedies were…

The purpose of the current study is to examine the relationships between need satisfaction, motivation, and outcomes as well as the differential effects of the three psychological needs. The sample consisted of 1549 students from 10 secondary schools in Singapore. Structural equation modelling (SEM) analysis showed that students' psychological needs are positively related to autonomous motivation, and this in turn, lead to higher enjoyment, value and lower pressure. On the other hand, the three psychological needs were negatively related to controlled motivation. Controlled motivation was positively related to pressure but negatively related to enjoyment and value. In terms of the differential effects of the three psychological needs, relatedness contributed strongly to autonomous motivation, compared to autonomy and competence. In contrast, while autonomy and relatedness contributed to controlled motivation negatively, competence positively predicted controlled motivation. Finally, competence was found to link to pressure in a negative way. In summary, the findings of the current…

The aim of the current work is to explore how heat transfer can be enhanced by variations in the basic properties of fluids in the presence of free convection with the aid of suspended hybrid nanofluids. Also, the influence of the Laurentz force on the flow is considered. The mathematical equations are converted into a pair of self-similarity equations by applying appropriate transformations. The reduced similarity equivalences are then solved numerically by Runge-Kutta-Fehlberg 45 th -order method. To gain better perception of the problem, the flow and energy transfer characteristics are explored for distinct values of significant factors such as variable viscosity, convection, magnetic field, and volume fraction. The results acquired are in good agreement with previously published results. The noteworthy finding is that the thermal conductivity is greater in hybrid nanofluid than that of a regular nanofluid in the presence of specified factors. The boundary layer thickness of both hybrid nanofluid and normal nanofluid diminishes due to decrease in variable viscosity. The fluid…

Studies conducted on resource management in wireless sensor networks have identified energy efficient routing protocols as one of the energy saving mechanisms that can be used to manage the consumption of networks' available energy and extend network lifetime. Routing protocols assist in finding paths for transmission of sensed events, and they must be able to extend the lifetime of a network despite some of the limitations of sensor nodes in a network and the harsh environments in which the sensor nodes are to operate. In this paper, we survey and compare existing routing protocols in wireless sensor networks. We start by introducing the different solutions that can be used to improve the network lifetime and focus on energy efficient routing protocols as the area of the survey, in addition to network topology modeling. We also model the network regarding energy consumption, sensing and event extraction analysis in the network. Categorization of the routing protocols into homogeneous and heterogeneous was performed, for which, sub-classification into static and mobile and other…

Carbon capture and storage (CCS) is a technology enabling to use fossil fuels in a sustainable way. Therefore, it attracts much attention from the industrial sector, government authorities and scientific community. However, public awareness of the technology is extremely low, and the studies of the lay people's opinion have been launched only during the last decade. Taking into account the role of public support during the implementation of CCS projects, the authors would like to present herein their review of materials on this subject published during 2002-2018 (135 articles). As part of our review, we determined 9 key aspects forming the public perception of CCS. For each of the key aspects, we summarized the available results of the studies. Apart from that, we compared the CCS current status in different countries and provided a number of reasons for involving new countries into the fight against global warming. This work shows that most attention is devoted to CO2 storage; whereas its capture and transportation are poorly studied in terms of public perception. Wider development…

In the present work, kaolin sample from Gbako Local Government, Niger State, Nigeria was used as an adsorbent for the removal chloride, COD, BOD, sulphate, chromium, cadmium, zinc and the reduction of total alkalinity in tannery wastewater. The kaolin sample was pretreated to enhance its adsorption capacity and then characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), High Resolution Electron Microscopy (HRSEM), High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive Spectroscopy (EDX), Selective Area Electron Diffraction (SAED) and Brunauer Emmett-Teller (BET). The specific surface area, pore volume and pore diameter of the kaolin were 17 m 2 /g, 0.018 cm 3 /g and 3.587 nm, respectively. The adsorption methods of the parameters onto the kaolin were investigated as functions of contact time, adsorbent dosage and temperature. Equilibrium isotherms for the adsorption parameters were carried out experimentally and the adsorption data correlated very well with Jovanovic and Redlich-Peterson models. Furthermore, the adsorption…

Towards the utilization of different parts of date palm biomass waste, low-concentration acid-alkali treatment was used to isolate the contained cellulose and α-cellulose. The cellulose yields achieved from the rachis, leaflet, and fiber parts of the biomass were 74.70%, 71.50%, and 73.82%, respectively, while the corresponding α-cellulose yields were 78.63%, 75.64%, and 70.40%, respectively. The cellulose samples were bleached and characterized by thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The XRD results revealed high crystallinity of both the cellulose and α-cellulose samples, while the TGA thermograms indicated that the alkali treatment completely removed lignin and hemicelluloses from the rachis. The results of this study demonstrate the promise of using date palm biomass waste as raw material to produce cellulose and α-cellulose.

Research studies on educational data mining are on the increase due to the benefits obtained from the knowledge acquired from machine learning processes which help to improve decision making processes in higher institutions of learning. In this study, predictive analysis was carried out to determine the extent to which the fifth year and final Cumulative Grade Point Average (CGPA) of engineering students in a Nigerian University can be determined using the program of study, the year of entry and the Grade Point Average (GPA) for the first three years of study as inputs into a Konstanz Information Miner (KNIME) based data mining model. Six data mining algorithms were considered, and a maximum accuracy of 89.15% was achieved. The result was verified using both linear and pure quadratic regression models, and R 2 values of 0.955 and 0.957 were recorded for both cases. This creates an opportunity for identifying students that may graduate with poor results or may not graduate at all, so that early intervention may be deployed.

The advancement in the field of material science has gifted us new electrically conductive materials having good mechanical properties and thermal characteristics. Machining these materials using conventional machining process is a challenging task. Electrical discharge machining (EDM) is a well-established machining process used to manufacture process hard materials having geometrically complex shapes, that are extremely difficult to machine traditionally. EDM is a thermo-electric process in which material is eroded by rapidly recurring sparks between the non-contacted electrode and workpiece. As there is no direct contact between the electrodes in EDM, machining defects like mechanical stresses, clattering & vibration do not create problems during machining. In spite of the advantages of the process, its use in industry is limited owing to poor surface finish and low volumetric material removal. To overcome these drawbacks, the metallic powder is mixed in the dielectric fluid, which increases its conductive strength and increases the spark gap distance between the tool and…

Caralluma dalzielii N. E. Brown (Asclepiadaceae) is a cactus-like shaped shrub widely used in traditional medicine for the treatment of rheumatoid arthritis, diabetes, infertility and impotence. The present study evaluated the potential toxicity of aqueous extract of aerial parts of Caralluma dalzielii (AECD) through acute and sub-acute oral administration in mice and rats. During acute toxicity study, female mice and rats were orally administered with AECD at single doses of 175, 500 and 2000 mg/kg according to OECD Guidelines 425. Sub-acute toxicity of AECD (150, 300 and 600 mg/kg p.o) was studied by daily dosing of Wistar rats of both sexes for 28 days. The acute toxicity study revealed no lethal effects and behavioural signs of toxicity at the tested doses indicating that LD 50 is greater than 2000 mg/kg. In sub-acute study, a significant reduction in the body weight ( p < 0.05), feed and water ( p < 0.001) intake of the rats were observed. A significant ( p < 0.05) increase in lymphocytes, mean platelet volume counts and alanine aminotransferase were also observed.…

In recent times, Augmented Reality has gained more relevance in the field of education. This relevance has been enhanced due to its ease of use, as well as the availability of the technical devices for the students. The present study was conducted with students enrolled in the Pedagogy Degree in the Faculty of Education at the University of Seville. The objective was to understand the degree of technological acceptance of students during their interaction with the AR objects produced, the performance achieved by the students, and if their gender affected their acquisition of knowledge. For this, three data collection instruments were utilized: a multiple choice test for the analysis of the student's performance after the interaction, the Technology Acceptance Model (TAM) diagnostic instrument, created by Davis (1989), and an "ad hoc" instrument created so that the students could evaluate the class notes enriched with the AR objects created. The study has allowed us to broaden the scientific knowledge of the TAM by Davis, to understand that AR objects can be utilized in university…

It is vital to understand processes of microplastic ingestion and egestion by aquatic organisms in order to evaluate the potential effects and impacts of microplastics in aquatic ecosystems. In this study, goldfish ( Carassius auratus ) was used to investigate ingestion and egestion of polyethylene (PE) microplastics and how these processes were affected by size, color, and shape of microplastics. Results showed that goldfish ingested white PE microplastics only in the presence of fish feed and that microplastics larger than 2 mm were rejected even after being ingested. However, in the presence of food, more green and black microplastics were ingested compared with red, blue, and white microplastics while significantly higher amounts of microplastic films were ingested compared with fragments and filaments. Microplastics ingested by goldfish were egested within 72 h. However, the egestion rate of filaments was the lowest among all tested microplastic shapes. The presence of food appeared to reduce film and filament residues in fish after 72 h. Results of this study imply that…

The environmental effects of urbanization and globalization are still subject to debate among scholars. South Africa is the most globalized, most urbanized and the most carbon-intensive economy in Sub Saharan Africa (SSA) region. Taking this into cognizance, this study examines the effects of urbanization and globalization on CO 2 emissions for South Africa using time series annual data for the period 1980–2017. Zivot and Andrews single and Bai and Perron multiple structural break unit root tests are employed to assess if all the series are stationary. This procedure follows ARDL cointegration test to check the presence of a long-run association among variables. Having been confirmed about such a cointegrating relation, ARDL short-run and long run coefficients indicate that urbanization induces CO 2 emissions while only long-run significant emissions effect of globalization was noted. Toda-Yamamoto non-causality test reports a bi-directional causal link between urbanization and CO 2 emissions. No causal link is observed between globalization and CO 2 emissions. Variance…

Climate variability and ecological changes have consequently altered life and natural livelihood-sustaining systems leading to socio-cultural, economic and environmental challenges and vulnerabilities. The risk factors are very high and the impacts will raise the developmental impediments of safeguarding livelihood security and poverty eradication in Sub-Saharan Africa. Adaptation to climate and ecological variation, though recognized as pressing and necessary, operates in the context of numerous uncertainties and unknowns. Previous studies on climate adaptation tried to identify universal patterns of coping rather than differentiating between agro ecological zones, villages and types of households. This paper uses case studies from two rural communities in the Savanna agro ecological zone of Ghana to explore smallholder farmers' responses to climate and ecological variation effects on their livelihood activities that have emerged since the mid-1980s. Results suggest that smallholder farmers use various coping, on-farm and off-farm adaptation strategies to ameliorate the negative…

The release of Non-Steroidal Anti-Inflammatory drugs (NSAIDs) such as Ibuprofen (Ibu), Naproxen (Nab) and Diclofenac (Dic) to the aquatic system cause serious environmental problems. In this study, green-synthesized copper nanoparticles (Cu NPs) have been used as nano-adsorbent for the removal of Ibu, Nab, and Dic from wastewater samples. Formation of Cu NPs was confirmed by different analytical techniques. The adsorption parameters such as temperature, pH, adsorbate concentration, adsorbent dose and contact time were studied. The best removal results were obtained at these conditions: temperature 298 K, pH = 4.5, 10.0 mg Cu NPs, 60 min. At these conditions, the removal percentage of Ibu, Nap, and Dic were found to be 74.4, 86.9 and 91.4% respectively. The maximum monolayer adsorption capacities were calculated as 36.0, 33.9 and 33.9 mg/g for Dic, Nap, and Ibu respectively. The kinetic studies conducted that the sorption process obeyed the second order kinetic model, while the thermodynamic results revealed that the adsorption process was spontaneous, endothermic (+23.8, +40.8 and…

Micronutrient malnutrition is an important issue in the developing countries especially in Asia and Africa where millions of school-going children and pregnant women are affected. Poor people are more exposed to risks of malnutrition and hidden hunger due to intake of carbohydrate rich but micronutrient deficient plant based food. The expansion of high yielding but micronutrient poor cultivars further intensified the malnutrition. The existing approaches viz ., supplementation and food fortification of staple food with minerals and vitamins can address the issue of adequate nutrition security. But supplementation and fortification is neither feasible for each nutrient specially iron nor viable due to recurrent cost. Recently, genetic bio-fortification of crops is emerged as self-targeted and non-recurrent approach to address the micronutrient malnutrition. Most of the traditional breeding approaches were limited due to non-availability of enough genetic variation in the crossable genepools. Additionally, it also lacks the modulation of target gene expression underlying the…

Purpose Dental caries is a multi-factorial oral disease, requiring a susceptible host, cariogenic microorganisms and suitable substrate. Caries is extended worldwide in spite of the availability of countless prophylactic means, including fluoride toothpaste and dental sealers. Many efforts have been made to achieve isolation of pure natural products for medicinal use. Flavonoids are bioactive polyphenol compounds possessing multidimensional effects such as antibacterial action. Methods The present study targeted the characterization of antibacterial and antifungal activity of various flavonoids (apigenin, catechin, luteolin, morin, myricetin, naringin, quercetin and rutin). Nine strains present in dental plaque were used: Agreggatibacter actinomycetemcomitans, Actinomyces naeslundii, Actinomyces viscosus, Enterococcus faecalis, Escherichia coli, Lactobacillus casei, Staphylococcus aureus, Streptococcus oralis and Streptococcus sanguinis as well as Candida albicans fungal strain. Results Results revealed that luteolin, morin, naringin, quercetin and rutin effectively inhibited…

The aim of the work is to synthesize iron oxide (α-Fe 2 O 3 ) nanoparticles using Sida cordifolia plant extract along with evaluation of its antibacterial activity. The presence of phytochemicals in Sida cordifolia methanolic plant extract was investigated by HPTLC and LC-MS/TOF. The probable mechanism for formation of α-Fe 2 O 3 nanoparticles in mediation with plant extract was demonstrated. The green synthesized iron oxide nanoparticles (α-Fe 2 O 3 NPs) were characterized by using X-ray diffraction, scanning, and transmission electronic microscopy, TG-DTA, FTIR, and UV spectroscopy. The crystallite size of prepared α-Fe 2 O 3 nanoparticles estimated via Debye-Scherrer formula and Williamson-Hall plot was around 20 nm which is in accordance with particle size in TEM images. The S. cordifolia mediated iron-oxide nanoparticles (α-Fe 2 O 3 NPs) hold potent antibacterial activity against various gram positive and gram negative bacteria.

L) used in chocolate making: Forastero, Trinitario and Criollo, which are distinguished by their aroma, an attribute that determines their quality. Criollo cocoa is of the highest quality and is used in the manufacture of fine chocolates because of its fruity aroma. The aroma of Criollo cocoa is defined by volatile compounds such as pyrazines and aldehydes, which are formed during roasting of the bean, from aroma precursors (reducing sugars and free amino acids) that are generated inside the bean via enzymatic reactions during fermentation; for this reason, fermentation is the most important process in the value chain. This review discusses the production of aroma precursors of Criollo and Forastero cocoa by studying the kinetics of spontaneous fermentation and the role of starter cultures to produce aroma precursors. Fine aroma precursors produced in the pulp during the fermentation phase will migrate into the bean when it's permeability is improved and then retained during the drying phase. Diffusion of aroma precursors into the cocoa bean may be possible, this process is…

Zirconium phosphates (ZrP) were incorporated into Nafion® 117 membrane by impregnating method to obtain a reduced methanol permeation and improved proton conductivity for fuel cell application. The mechanical properties and water uptake of Nafion® membrane incorporated with zirconium phosphates nanoparticles was more improvement when compared to the commercial Nafion® 117, due to the presence of phosphoric acid within the nanoparticles. The effect of ZrP nano filler on the membrane structural morphology and thermal properties were investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermal gravimetric analysis (TGA) and Scanning Electron Microscopy (SEM). The improved ion conductivity and decreased methanol permeability on the nanocomposite membranes showed a great potential for fuel cell applications. The nanocomposite membrane with high tensile strength was obtained due to the well dispersed zirconium phosphates within the Nafion® matrix.

The integration of floating a PV plant (FPV) with a Hydroelectric Power plant (HPP) is studied and it is shown that several advantages come from this hybridization. The FPV power potential is analysed for the first 20 largest HPPs in the world and it is shown that when covering 10% of the HPP basin surfaces the HPP energy production is increased by 65%. The experience of China Longyangxa basin and of its connected PV power plant is examined together with the suggestion to install a FPV whose rated power is equal to HPP rated power. This hypothesis is applied to an analysis of the geographic potential worldwide and it is shown that covering 2.4% of the existing HPP basin surfaces the energy produced by HPP will be increased by 35.9%. The advantages of the coupling of the two power production technologies are discussed.

Lemon myrtle ( Backhousia citriodora ) is one of the most commercially grown native herbs in Australia. This study aimed to evaluate the effects of different drying methods on phenolic compounds and antioxidant properties of lemon myrtle leaves to identify the most suitable drying conditions. The drying methods include hot air drying, vacuum drying, microwave drying, sun drying, shade drying and freeze drying. The results showed that drying conditions significantly ( p < 0.05) affected the retention of total phenolic content (TPC), total flavonoids (TFC), proanthocyanidins, gallic acid, hesperetin, and antioxidant properties of lemon myrtle leaves. The optimal conditions for hot air drying and vacuum drying are 90 °C for 75 min and 90 °C for 120 min, respectively; whereas optimal drying conditions for microwave drying are 960 W for 7 min, and the time required for sun drying and shade drying are 2 days and 12 days, respectively. The freeze dried leaves contained the highest level of TPC, TFC, proanthocyanidins, gallic acid and hesperetin (74.11 ± 2.87 mg GAE/g dw, 87.15 ± 2.70 mg…