19672 research outputs found
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Antibacterial activity against bacillus subtilis and antioxidant properties of methanol extracts from garcinia latissima miq. Leaves
No full textObjective: The objective of this study was to identify fractions with the highest antibacterial activity against Bacillus subtilis and to determine antioxidant activities and establish the chromatographic fractions as candidate antibacterial and antioxidant agents. Methods: Extracts were fractionated using column chromatography, and antibacterial activities were assayed by the analyses of inhibition zones and bioautography, as well as by broth microdilution techniques. Antioxidant activities were evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Results: The strongest antibacterial activity against B. subtilis (ATCC 6633) was observed with fractions B and C obtained in this research, with a minimum inhibitory concentration value of 312.5 μg/mL. The effective percentage (EP) value of crude extract at 10 μg/mL was 29.47±2.01%. Fractions C and D had greater EP values than the crude extract, whereas fraction D had the highest scavenging activity against DPPH free radicals (37.73±1.44%) when used at 10 μg/mL. The half effective concentration of the extract was 23.40 μg/mL, whereas that of the most active fraction D was 19.38 μg/mL and quercetin as positive control was 3.72 μg/mL. Conclusion: The present data confirm that fractions of methanol extract from Garcinia latissima Miq. leaves possess antibacterial and antioxidant activities. These observations may facilitate the development of antimicrobial phytomedicines with a wide spectrum of activities and standardized antioxidant properties
Heat-treated palm oil fuel ash as an effective supplementary cementitious material originating from agriculture waste
No full textPalm oil fuel ash (POFA) is generated from the combustion of oil palm waste. This ash is considered a disturbance to the environment since it is dumped without being profit return or recycled, thus causing environmental problems and human health hazards. However, it has been proven that POFA is a pozzolanic material that can be utilized as cement replacement in concrete. If POFA is heated at high temperature, it exhibits better pozzolanic performance. In this study, the treatment processes as well as microstructure and pozzolanic characteristics of POFA are considered. Ordinary Portland cement was replaced with 0, 30, 50, and 70% treated POFA (T-POFA) in a paste. The hydration products of different hardened pastes were checked by means of simultaneous thermal analysis (STA), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) in order to assess the effect of TPOFA on the paste microstructure. According to the test results, the physical properties and chemical composition of T-POFA greatly enhanced due to heat treatment and the milling process. It was observed that the calcium hydroxide content decreased in pastes containing T-POFA upon hardening, which is evidence of its consumption by the pozzolanic reaction. The FESEM images displayed needle-like and reticular C–S–H phases in the control paste, while floc-like and fibrous-like C–S–H phases well-connected to each other were observed in the pastes containing T-POFA
A systematic literature review on vision based gesture recognition techniques
No full textHuman Computer Interaction (HCI) technologies are rapidly evolving the way we interact with computing devices and adapting to the constantly increasing demands of modern paradigms. One of the most useful tools in this regard is the integration of Human-to-Human Interaction gestures to facilitate communication and expressing ideas. Gesture recognition requires the integration of postures, gestures, face expressions and movements for communicating or conveying certain messages. The aim of this study is to aggregate and synthesize experiences and accumulated knowledge about Vision-Based Recognition (VBR) techniques. The major objective of conducting this Systematic Literature Review (SLR) is to highlight the state-of-the-art in the context of vision-based gesture recognition with specific focus on hand gesture recognition (HGR) techniques and enabling technologies. After a careful systematic selection process, 100 studies relevant to the four research questions were selected. This process was followed by data collection, a detailed analysis, and a synthesis of the selected studies. The results reveal that among the VBR techniques, HGR is a predominant and highly focused area of research. Research focus is also found to be converging towards sign language recognition. Potential applications of HGR techniques include desktop applications, smart environments, entertainment, sign language interpretation, virtual reality and gamification. Although various experimental research efforts have been devoted to gestures recognition, there are still numerous open issues and research challenges in this field. Lastly, considering the results from this SLR, potential future research directions are suggested, including a much needed focus on grammatical interpretation, hybrid approaches, smartphone devices, normalization, and real-life systems
Q-switched and mode-locked ytterbium-doped fibre lasers with Sb2Te3 topological insulator saturable absorber
No full textQ-switched and mode-locked fibre lasers have been successfully demonstrated in ytterbium-doped fibre laser cavity by taking an advantage of the optical absorption of antimony telluride (Sb 2 Te 3 ) material. The Sb 2 Te 3 was embedded into polyvinyl alcohol to function as a saturable absorber (SA). A Q-switching pulses train was obtained by incorporating the SA into the laser ring cavity configured with 3 dB coupler. The Q-switching pulse repetition rate increases from 24.4 to 55 kHz as the pump power is increased from the threshold of 75.4-96.2 mW. The maximum pulse energy of 252.6 nJ is obtained at 82.3 mW pump power. On the other hand, by changing the output coupler to 10 dB coupler, a stable self-started mode-locking operation was then generated at pump power range from 47.8 to 89.4 mW with a fixed repetition rate of 24.2 MHz. At 89.4 mW pump power, the maximum output power and pulse energy are obtained to be around 18.6 mW and 0.8 nJ, respectively. The authors results display that the Sb 2 Te 3 material could also be developed as an effective SA for both Q-switched and mode-locked fibre lasers
Band engineered Al-rich InAlN thin films as a promising photoanode for hydrogen generation from solar water splitting
No full textIn this study, Al-rich InAlN thin films were grown at different substrate temperatures (Ts) by plasma-assisted dual source reactive evaporation and effects of the parameter on indium incorporation, morphology, structural and optical properties of the alloys were investigated. It was shown that indium content of the films increases at higher substrate temperature and the bandgap is decreased from 3.54 to 2.76 eV as Ts increases from 150° to 400 °C, respectively. The photoelectrochemical (PEC) activity of the deposited films targeted for solar water splitting application was examined in the presence of simulated solar irradiation of AM 1.5 G (100 mW/cm2). The PEC measurements revealed a massive improvement in the photocurrent density for the InAlN sample deposited at Ts = 400 °C compared with the films grown at 150 °C. From the Mott-Schottky (MS) plots it was concluded that by increasing Ts up to 400 °C, charge transport during PEC process could be facilitated. It was shown that Al-rich InAlN with selected band gap and band alignments could be a potential candidate for PEC water splitting
Evaluation of production cross-sections for 186 Re theranostic radionuclide via charged-particle induced reactions on Tungsten
No full text186Re (T1/2 = 89.24 h, E(β−)mean= 346.7 keV, I(β−)total=92.59%), an intense beta-emitter shows great potential to be used as an active material in therapeutic radiopharmaceuticals due to its suitable physico-chemical properties. 186Re can be produced in several ways, however charged-particle induced reactions show to be promising towards no carrier added production. In this work, production cross-sections of 186Re were evaluated following the light-charged particle induced reactions on tungsten. An effective evaluation technique such as Simultaneous Evaluation on KALMAN code combined with least squares concept was used to obtain the evaluated data together with covariances. Knowledge of the underlying uncertainties in evaluated nuclear data, i.e., covariances are useful to improve the accuracy of nuclear data
Gelatin controversies in food, pharmaceuticals, and personal care products: Authentication methods, current status, and future challenges
No full textGelatin is a highly purified animal protein of pig, cow, and fish origins and is extensively used in food, pharmaceuticals, and personal care products. However, the acceptability of gelatin products greatly depends on the animal sources of the gelatin. Porcine and bovine gelatins have attractive features but limited acceptance because of religious prohibitions and potential zoonotic threats, whereas fish gelatin is welcomed in all religions and cultures. Thus, source authentication is a must for gelatin products but it is greatly challenging due to the breakdown of both protein and DNA biomarkers in processed gelatins. Therefore, several methods have been proposed for gelatin identification, but a comprehensive and systematic document that includes all of the techniques does not exist. This up-to-date review addresses this research gap and presents, in an accessible format, the major gelatin source authentication techniques, which are primarily nucleic acid and protein based. Instead of presenting these methods in paragraph form which needs much attention in reading, the major methods are schematically depicted, and their comparative features are tabulated. Future technologies are forecasted, and challenges are outlined. Overall, this review paper has the merit to serve as a reference guide for the production and application of gelatin in academia and industry and will act as a platform for the development of improved methods for gelatin authentication
Calibration Model of a Low-Cost Air Quality Sensor Using an Adaptive Neuro-Fuzzy Inference System
No full textConventional air quality monitoring systems, such as gas analysers, are commonly used in many developed and developing countries to monitor air quality. However, these techniques have high costs associated with both installation and maintenance. One possible solution to complement these techniques is the application of low-cost air quality sensors (LAQSs), which have the potential to give higher spatial and temporal data of gas pollutants with high precision and accuracy. In this paper, we present DiracSense, a custom-made LAQS that monitors the gas pollutants ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO). The aim of this study is to investigate its performance based on laboratory calibration and field experiments. Several model calibrations were developed to improve the accuracy and performance of the LAQS. Laboratory calibrations were carried out to determine the zero offset and sensitivities of each sensor. The results showed that the sensor performed with a highly linear correlation with the reference instrument with a response-time rangefrom 0.5 to 1.7 min. The performance of several calibration models including a calibrated simple equation and supervised learning algorithms (adaptive neuro-fuzzy inference system or ANFIS and the multilayer feed-forward perceptron or MLP) were compared. The field calibration focused on O3 measurements due to the lack of a reference instrument for CO and NO2. Combinations of inputs were evaluated during the development of the supervised learning algorithm. The validation results demonstrated that the ANFIS model with four inputs (WE OX, AE OX, T, and NO2) had the lowest error in terms of statistical performance and the highest correlation coefficients with respect to the reference instrument (0.8 < r < 0.95). These results suggest that the ANFIS model is promising as a calibration tool since it has the capability to improve the accuracy and performance of the low-cost electrochemical sensor
Synthesis and Characterization of Cu2CdSnS4 Quaternary Alloy Nanostructures
No full textCu2CdSnS4 (CCTS) quaternary alloy nanostructure is an important material of enhancing the sensors effectiveness. CCTS nanostructures have been synthesized using ultrasonic and deposited on SiO2/Si substrate using sol-gel method and under annealing temperature; 400 oC. Structural optical, topographical and morphological properties of CCTS were explored using Ultraviolet-visible spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. Interdigitated electrodes (IDEs) have been manufactured via deposited silver on CCTS/SiO2/Si substrate via a physical vapor deposition and hard mask. Electrical properties of fabricated IDEs are further evaluated as a function of voltage and frequency. The proposed IDEs can be used in subsequent studies to develop a biological sensor capable of detecting the DNA for many types of diseases in order to facilitate the combating and eradicating. The resulted values are in agreement with others
Algorithmic design issues in adaptive differential evolution schemes: Review and taxonomy
No full textThe performance of most metaheuristic algorithms depends on parameters whose settings essentially serve as a key function in determining the quality of the solution and the efficiency of the search. A trend that has emerged recently is to make the algorithm parameters automatically adapt to different problems during optimization, thereby liberating the user from the tedious and time-consuming task of manual setting. These fine-tuning techniques continue to be the object of ongoing research. Differential evolution (DE) is a simple yet powerful population-based metaheuristic. It has demonstrated good convergence, and its principles are easy to understand. DE is very sensitive to its parameter settings and mutation strategy; thus, this study aims to investigate these settings with the diverse versions of adaptive DE algorithms. This study has two main objectives: (1) to present an extension for the original taxonomy of evolutionary algorithms (EAs) parameter settings that has been overlooked by prior research and therefore minimize any confusion that might arise from the former taxonomy and (2) to investigate the various algorithmic design schemes that have been used in the different variants of adaptive DE and convey them in a new classification style. In other words, this study describes in depth the structural analysis and working principle that underlie the promising and recent work in this field, to analyze their advantages and disadvantages and to gain future insights that can further improve these algorithms. Finally, the interpretation of the literature and the comparative analysis of the algorithmic schemes offer several guidelines for designing and implementing adaptive DE algorithms. The proposed design framework provides readers with the main steps required to integrate any proposed meta-algorithm into parameter and/or strategy adaptation schemes