Showing papers in "Journal of King Saud University - Science in 2017"
TL;DR: Bimetallic nanoparticles (BNPs) are formed by the combination of two different metals and have attracted huge attention in both technological and scientific view because BNPs shows better properties as mentioned in this paper.
Abstract: Bimetallic nanoparticles (BNPs) are formed by the combination of two different metals. Bimetallic nanoparticles have attracted huge attention as compared to monometallic nanoparticles in both technological and scientific view because BNPs shows better properties. Bimetallic nanoparticles can be synthesized in different shape, size and structure. The nanocomposites of BNPs have been prepared by supporting them on the organic or inorganic counterparts. BNPs nanocomposites have improved properties as compared to those of bimetallic nanoparticles. Due to reduction in size and increase in surface area, these are prominently used as catalyst. Application area of bimetallic nanocomposites includes drug delivery, water purification and catalysis etc.
402 citations
TL;DR: In this paper, the groundwater potential zones were delineated by adopting a frequency ratio (FR) model, where land use and land cover, hydro geomorphology, slope, geology, lineament density, drainage density, and ground water level were the thematic factors considered for groundwater potential zone mapping.
Abstract: Groundwater potential mapping and its sustainable development are an important aspect in Leh valley due to an increase of tourists and the local population. In the present study, the groundwater potential zones were delineated by adopting a frequency ratio (FR) model. Land use and land cover, hydro geomorphology, slope, geology, lineament density, drainage density, spring well locations and ground water level were the thematic factors considered for groundwater potential zone mapping. There are 86 spring wells located in the study area, of which 60 wells were considered for success rate and remaining 26 wells considered for prediction rate in the FR model. The final groundwater potential map was classified into five zones as very high, high, moderate, low, and very low. The success and prediction rates of FR model were measured as 81.25% and 77.23% respectively. Water budget of the valley was also calculated on the basis of consumption, demand and supply of water by taking account of the floating population. There is a huge demand of water supply requirement during the tourist season from May to September months and deficiency of water in the area was calculated as 4,224,557 (in l). Finally, suitable sites for artificial recharge for sustainable groundwater management were identified. The sites were selected on the basis of depth of groundwater level, source of spring well locations and gradient from natural spring to selected recharge wells.
156 citations
TL;DR: In this paper, an alternative method for temperature prediction by combining the wavelet technique with an autoregressive integrated moving average (ARIMA) model and an artificial neural network (ANN) applied to monthly maximum and minimum temperature data is presented.
Abstract: Time-series analyses of temperature data are important for investigating temperature variation and predicting temperature change. Here, Mann–Kendall (M–K) analyses of temperature time-series data in northeastern Bangladesh indicated increasing trends (Sen’s slope of maximum and minimum yearly temperature at Sylhet of 0.03 °C and 0.026 °C, respectively, and a minimum temperature at Sreemangal of 0.024 °C) except for the maximum temperature at Sreemangal. The linear trends showed that the maximum temperature is increasing by 2.97 °C and 0.59 °C per hundred years, and the minimum, by 2.17 °C and 2.73 °C per hundred years at the Sylhet and Sreemangal stations, indicating that climate change is affecting temperature in this area. This paper presents an alternative method for temperature prediction by combining the wavelet technique with an autoregressive integrated moving average (ARIMA) model and an artificial neural network (ANN) applied to monthly maximum and minimum temperature data. The data are divided into a training dataset (1957–2000) to construct the models and a testing dataset (2001–2012) to estimate their performance. The calibration and validation performance of the models is evaluated statistically, and the relative performance based on the predictive capability of out-of-sample forecasts is assessed. The results indicate that the wavelet-ARIMA model is more effective than the wavelet-ANN model.
111 citations
TL;DR: In this article, the effect of slip condition on MHD free convective flow of non-Newtonian fluid over a nonlinearly stretching sheet saturated in porous medium with Newtonian heating is analyzed.
Abstract: The effect of slip condition on MHD free convective flow of non-Newtonian fluid over a nonlinearly stretching sheet saturated in porous medium with Newtonian heating is analyzed. The governing nonlinear coupled partial differential equations with auxiliary conditions are transformed into the system of coupled ordinary differential equations via similarity transformations and then solved numerically using Keller-box method. The results for skin friction coefficient and the reduced Nusselt number are obtained and compared with previous results in the literature and are found to be in excellent agreement. Results show that the slip parameter reduces the velocity of Casson fluid and enhances the shear stress. It is also observed that slip effect is more pronounced on temperature profile in comparison with velocity profile. It is also seen that velocity and dimensionless temperature are increasing functions of Newtonian heating parameter. Further, temperature gradient is an increasing function of thermal buoyancy parameter and Newtonian heating parameter whereas a decreasing function of porosity parameter and nonlinear stretching sheet parameter.
103 citations
TL;DR: The present study on essential oils deriving from the Mentha × piperita L. species could be used in antimicrobial activity as a natural source.
Abstract: This research studied the chemical constituents and antibacterial activity of essential oils from the areal parts of Mentha × piperita L. essential oil. Essential oil was subjected to hydrodistillation for 4 h using Clevenger apparatus, resulting in nineteen chemical constituents representing 100% of the essential oil, comprising menthol (36.02%), menthone (24.56%), menthyl acetate (8.95%), and menthofuran (6.88%); these are major components, and others are minor components. Essential oil shows significant antibacterial and antifungal activity than principle components. The essential oil shows significant antibacterial activity against human pathogenic micro-organisms. Further, Staphylococcus aureus (42.44 ± 0.10 mm), Micrococcus flavus (40.01 ± 0.10 mm) , Bacillus subtilis (38.18 ± 0.11 mm), Staphylococcus epidermidis (35.14 ± 0.08 mm), and Salmonella enteritides (30.12 ± 0.12 mm) show the highest antibacterial activity against essential oils. Essential oils show significant antifungal activity against Alternaria alternaria (38.16 ± 0.10 mm), Fusarium tabacinum (35.24 ± 0.03 mm), Penicillum spp. (34.10 ± 0.02 mm), Fusarium oxyporum (33.44 ± 0.06 mm), and Aspergillus fumigates (30.08 ± 0.08 mm). The maximal and minimal inhibition concentration values are in the range of 10.22 ± 0.17 to 38.16 ± 0.10 and 0.50 ± 0.03 to 10.0 ± 0.14 μg/ml, for yeast and fungi respectively. The present study on essential oils deriving from the Mentha × piperita L. species could be used in antimicrobial activity as a natural source.
101 citations
TL;DR: Alkaloids, tannins and terpenoids were the secondary metabolites most frequently found, while flavonoids, quinones, anthraquinones, steroids and saponins were present in less proportion.
Abstract: Phytochemical screening of ethanolic extracts of Acnistus arborescens (L.) Schltdl. (Solanaceae); Albizia multiflora (Kunth) Barneby & J.W. Grimes (Fabaceae); Capparidastrum petiolare (Kunth) Hutch. (Capparaceae); Colicodendron scabridum (Kunth) Seem. (Capparaceae); Gronovia scandens L. (Loasaceae); Gustavia angustifolia Benth. (Lecythidaceae); Piscidia carthagenensis Jacq. (Fabaceae); Psidium rostratum Mc Vaugh (Myrtaceae); Psidium guayaquilense Landrum & Cornejo (Myrtaceae); Psidium cf. rostratum Mc Vaugh (Myrtaceae); Salicornia fruticosa L. (Amaranthaceae) ; Simira ecuadorensis (Standl.) Steyerm. (Rubiaceae); Ruellia floribunda Hook. (Acanthaceae) were assayed. Alkaloids, tannins and terpenoids were the secondary metabolites most frequently found, while flavonoids, quinones, anthraquinones, steroids and saponins were present in less proportion. Folin-Ciocalteu method was used to quantify the total phenolic content in the ethanolic extracts using a calibration curve of gallic acid. The range between 941.97 ± 30.69 and 241.54 ± 15.54 GAE/mg dry extract, has been observed for Psidium guayaquilense and Acnistus arborescens , respectively. On the other hand, antibacterial activity of the ethanolic extracts was evaluated using the disk diffusion agar method against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Vibrio parahaemolyticus ATCC 17802. P. rostratum , P. guayaquilense , P. cf. rostratum , R. floribunda and S. ecuadorensis were the most active extracts against the bacterial assays with minimal inhibitory concentration (MIC) values ranging between 20 and 100 ppm. According to literature, it is most likely that this is the first report on phytochemical screening, total phenolic content and antibacterial activity of ethanolic extracts of these species.
88 citations
TL;DR: A number of suggestions on how to achieve the systematization of data on the most relevant physico-chemical parameters, which govern and control the interaction between carrier and drug, are offered to give the reader an overview of the most significant advances in this field.
Abstract: In these years a variety of polymeric nanocarriers such as dendrimers, polymeric micelles, nanoparticles, nanogels, nanocapsules and vesicles are widely investigated as potential drug delivery systems. In addition to the different morphologies and sizes, these carriers may have on their surfaces specific functionalizations to improve the drug loading and controlled release and specific ligands for cell receptors, in order to achieve a precise targeting. This review focuses on recent functionalized polymeric nanomaterials used as drug delivery systems, with an emphasis on morphology and surface modifications of polymeric nanocarriers to improve controlled drug delivery. Moreover, this work offers a number of suggestions on how to achieve the systematization of data on the most relevant physico-chemical parameters, which govern and control the interaction between carrier and drug, with the aim to give the reader an overview of the most significant advances in this field.
82 citations
TL;DR: In this paper, a two-level factorial design was used to evaluate the significant extraction parameters in achieving higher recovery yield of extract, total phenolic content, total flavonoid content, and antioxidants from Vernonia amygdalina leaf.
Abstract: Vernonia amygdalina leaves are mostly consumed in Asia and Africa, due to its potential as a good source of antioxidants. In this study, a two-level factorial design was used to evaluate the significant extraction parameters in achieving higher recovery yield of extract, total phenolic content, total flavonoid content, and antioxidants from Vernonia amygdalina leaf. Microwave-assisted extraction technique was employed using aqueous ethanol. The independent parameters were irradiation time (1–5 min), microwave power level (500–700 W), temperature (60–80 °C), feed-to-solvent ratio (1:8–1:12 g/ml), and ethanol concentration (40–80%). Amongst the examined parameters, ethanol concentration, irradiation time, microwave power level, and feed-to-solvent ratio were significant (p Vernonia amygdalina leaf using MAE technique are significantly affected by ethanol concentration, irradiation time, microwave power and feed-to-solvent ratio.
80 citations
TL;DR: In this paper, the effect of process parameters on material removal rate (MRR) and surface roughness (Ra) in wire electric discharge machining of Inconel 625 was investigated.
Abstract: The present investigation focuses the effect of process parameters on material removal rate (MRR) and surface roughness (Ra) in wire electric discharge machining of Inconel 625. Machining was done by using a normal zinc coated wire and cryogenic treated zinc coated wire. The experiments were performed by considering different process parameters viz. tool electrode, current intensity, pulse on time, pulse off time, wire feed and wire tension. The thickness of work material and dia. of wire are kept constant. Taguchi L18 (2 1 * 3 5 ) orthogonal array of experimental design is used to perform the experiments. Analysis of variance (ANOVA) is employed to optimize the material removal rate and surface roughness. Based on analysis it is found that pulse on time, tool electrode and current intensity are the significant parameters that affect the material removal rate and surface roughness. The scanning electron microscopy (SEM) are used to identify the microstructure of the machined work piece.
79 citations
TL;DR: In this paper, the authors aimed to the biosynthesis of silver nanoparticles (AgNPs) using Lactobacillus mixture and evaluating their antioxidant activity, using Ultra Violet (UV)-Visible spectrophotometry Scanning electron microscope (SEM) was used to detect the size, shape and distribution of AgNPs and occurrence of elemental silver was analyzed by Energy Dispersive-X-ray Spectroscopy (EDS) analysis.
Abstract: Biosynthesis method of nanoparticles acquires very important area due to their economic and ecofriendly benefits The present study was aimed to the biosynthesis of silver nanoparticles (AgNPs) using Lactobacillus mixture and evaluating their antioxidant activity The characterization and biosynthesis AgNPs was achieved, using Ultra Violet (UV)–Visible spectrophotometry Scanning electron microscope (SEM) was used to detect the size, shape and distribution of AgNPs The occurrence of elemental silver was analyzed by Energy Dispersive-X-ray Spectroscopy (EDS) analysis To evaluate the antioxidant activity of AgNPs and Lactobacillus in vivo , forty healthy adult rats were used and divided into eight equal groups, first group served as control, second group received LAB mix1 (1 ml/kg) and three groups were administrated with three concentration of AgNPs (5, 50 and 500 mg/kg AgNPs) respectively and other three groups were administrated with the same concentration of AgNPs along with LAB mix1 for two weeks The results revealed significant increased (p The current study demonstrated that Lactobacillus afforded beneficial role by increasing the antioxidant activity with AgNPs and as ameliorative function for the effect of high dose of AgNPs
78 citations
TL;DR: In this article, the effects of suction as well as thermal radiation, chemical reaction, viscous dissipation and Joule heating on a two-dimensional natural convective flow of unsteady electrical magnetohydrodynamics (MHD) nanofluid over a linearly permeable stretching sheet were investigated.
Abstract: This paper focuses on the effects of suction as well as thermal radiation, chemical reaction, viscous dissipation and Joule heating on a two-dimensional natural convective flow of unsteady electrical magnetohydrodynamics (MHD) nanofluid over a linearly permeable stretching sheet. One significant aspect of this study is that electric field employed in revised Buongiorno model has been introduced in view of enhancement of thermal conductivity and consequently better convective heat transfer. The constitute governing equations have been converted into strong non-linear ordinary differential equations by employing suitable transformations and these transformed equations are solved by the Implicit finite difference. From this study, it is found that the presence of magnetic field and suction slows down the fluid motion while it enhances for higher values of an electric field which tends to firmness sticky effect. It is also found that enhancing thermal radiation leads to an increase in nanofluid temperature. The Nusselt number increases with both Brownian motion and unsteadiness parameters.
TL;DR: This review focused on the promising potential of green-fabricated nanoparticles as toxic agents against mosquito young instars, and as adult oviposition deterrents, and analyzed current evidences about non-target effects of these nanocomposites used for mosquito control.
Abstract: Mosquito control programs are facing important and timely challenges, including the recent outbreaks of novel arbovirus, the development of resistance in several Culicidae species, and the rapid spreading of highly invasive mosquitoes worldwide. Current control tools mainly rely on the employment of ( i ) synthetic or microbial pesticides, ( ii ) insecticide-treated bed nets, ( iii ) adult repellents, ( iv ) biological control agents against mosquito young instars (mainly fishes, amphibians and copepods) ( v ) Sterile Insect Technique (SIT), ( vi ) “boosted SIT”, ( vii ) symbiont-based methods and ( viii ) transgenic mosquitoes. Currently, none of these single strategies is fully successful. Novel eco-friendly strategies to manage mosquito vectors are urgently needed. The plant-mediated fabrication of nanoparticles is advantageous over chemical and physical methods, since it is cheap, single-step, and does not require high pressure, energy, temperature, or the use of highly toxic chemicals. In the latest years, a growing number of plant-borne compounds have been proposed for efficient and rapid extracellular synthesis of metal nanoparticles effective against mosquitoes at very low doses (i.e. 1–30 ppm). In this review, we focused on the promising potential of green-fabricated nanoparticles as toxic agents against mosquito young instars, and as adult oviposition deterrents. Furthermore, we analyzed current evidences about non-target effects of these nanocomposites used for mosquito control, pointing out their moderate acute toxicity for non-target aquatic organisms, absence of genotoxicity at the doses tested against mosquitoes, and the possibility to boost the predation rates of biological control agents against mosquitoes treating the aquatic environment with ultra-low doses (e.g. 1–3 ppm) of green-synthesized nanoparticles, which reduce the motility of mosquito larvae. Challenges for future research should shed light on ( i ) the precise mechanism(s) of action of green-fabricated metal nanoparticles, ( ii ) their fate in the aquatic environment, and ( iii ) the possible toxicity of residual silver ions in the aquatic ecosystems, ( iv ) the standardization of chemical composition of botanical products used as sources of reducing and capping metabolites, ( v ) the optimization of the green nanosynthetic routes, in order to develop large-scale production of eco-friendly nanomosquitocides.
TL;DR: This short review outlines the current state of the art in the field of EH-MEMS, with a specific focus on vibration EHs, i.e. converters capable to convert the mechanical energy scattered in environmental vibrations, into electric power.
Abstract: The paradigm of the Internet of Things (IoT) appears to be the common denominator of all distributed sensing applications, providing connectivity, interoperability and communication of smart entities (e.g. environments, objects) within a pervasive network. The IoT demands for smart, integrated, miniaturised and low-energy wireless nodes, typically powered by non-renewable energy storage units (batteries). The latter aspect poses constraints as batteries have a limited lifetime and often their replacement is impracticable. Availability of zero-power energy-autonomous technologies, able to harvest (i.e. convert) and store part of the energy available in the surrounding environment (vibrations, thermal gradients, electromagnetic waves) into electricity to supply wireless nodes functionality, would fill a significant part of the technology gap limiting the wide diffusion of efficient and cost effective IoT applications. Given the just depicted scenario, the realisation of miniaturised Energy Harvesters (EHs) leveraging on MEMS technology (MicroElectroMechanical-Systems), i.e. EH-MEMS, seems to be a key-enabling solution able to conjugate both main driving requirements of IoT applications, namely, energy-autonomy and miniaturisation/integration. This short review outlines the current state of the art in the field of EH-MEMS, with a specific focus on vibration EHs, i.e. converters capable to convert the mechanical energy scattered in environmental vibrations, into electric power. In particular, the issues in terms of conversion performance arising from EHs scaling down, along with the challenge to extend their operability on a frequency range of vibrations as wider as possible, are going to be discussed in the following.
TL;DR: In this article, the effect of laser peening without coating on the hardness of an aluminium alloy was investigated and the Vickers micro-hardness test was used to study the hardness with different wavelengths and laser intensities.
Abstract: Laser shock peening (LSP) is a surface treatment process for increasing the strength and reliability of metal components. Traditionally applied to composite structures of automotive and medical applications, the LSP technology also shows great potential for aircraft parts to improve the fatigue resistance of highly stressed critical aircraft turbine engine components, complex forming of wing surfaces, steam turbines, etc. The present study investigates the effect of laser peening without coating on the hardness of an aluminium alloy. The Vickers micro-hardness test is used to study the hardness of the Al alloy with different wavelengths and laser intensities. It is found that the metal hardness can be significantly increased to more than 80% by increasing the laser intensity and the number of laser shots irradiated per unit area.
TL;DR: Three effective-most plants in controlling MDR-UTI bacteria in vitro were A. acuminata, P. granatum and S. febrifuga, which can be promoted as complementary medicine.
Abstract: Urinary tract infection (UTI) has become a more grievous problem today, due to multidrug resistance of infecting Gram-positive (GP) and Gram-negative (GN) bacteria, sometimes even with multiple infections. This study examines effectivity of 9 tropical flowering plants ( Anogeissus acuminata , Azadirachta indica, Bauhinia variegata , Boerhaavia diffusa , Punica granatum , Soymida febrifuga , Terminalia chebula , Tinospora cordifolia and Tribulus terrestris ) for possible use as source of antimicrobials for multidrug resistant (MDR) bacteria, along with main-stream antibiotics. Pathogenic bacteria were isolated from urine samples of patients attending and admitted in the hospital. Antibiograms of 11 isolated bacteria (GPs, Enterococcus faecalis and Staphylococcus aureus ; and GNs, Acinetobacter baumannii , Citrobacter freundii , Enterobacter aerogenes , Escherichia coli , Klebsiella oxytoca , Klebsiella pneumoniae , Proteus mirabilis , Proteus vulgaris and Pseudomonas aeruginosa ) were ascertained by the disc-diffusion method, and antibacterial effectivity of plant extracts was monitored by the agar-well diffusion method. Isolated bacteria were floridly MDR to most antibiotics of the day. Methanol extracts of 9 plants were used, and extracts of 3 plants, A. acuminata , P. granatum and S. febrifuga at least caused 25–29 mm as the maximum size of zone of inhibition on bacterial lawns. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of methanol extracts of 9 plants were recorded. The methanol extract of A. acuminata had 0.29 mg/ml as the lowest MIC value and 0.67 mg/ml as the lowest MBC value, against MDR S. aureus , signifying effectivity; but, it had the highest MIC value of 3.41 mg/ml. and the highest MBC value of 4.27 mg/ml for most other MDR bacteria including E. coli . Qualitative phytochemical analysis was done for these 9 plants and information on leading phytochemicals was presented retrieved from PubChem database. Thus, three effective-most plants in controlling MDR-UTI bacteria in vitro were A. acuminata , P. granatum and S. febrifuga , which can be promoted as complementary medicine.
TL;DR: The investigated complexes have effective cytotoxicity against growth of carcinoma cells with respect of its imine ligand and have a stronger antimicrobial activity in comparison with its ligand.
Abstract: Two novel VO(II) and Mn(II) imine chelates derived from the condensation of o-phenylenediamine (PN) with 3-ethoxysalicylaldehyde(ES) were synthesized The prepared ESPN imine ligand and its chelates were investigated via different analytical and physicochemical tools Correlation between all the obtained results, the parent ligand behaves as tetra-dentate ONNO ligand and coordinates to Mn(II) and VO(II), in octahedral and square pyramidal geometry, respectively Also, the prepared compounds were screened for their antimicrobial activities on different pathogenic bacteria and fungi The results show that the complexes have a stronger antimicrobial activity in comparison with its ligand Moreover, the interaction of the prepared metal chelates with CT-DNA was detected utilizing spectral studies, viscosity and gel electrophoreses measurements The obtained results clearly demonstrate that, the binding affinity with CT-DNA for ESPN > ESPNV complex Furthermore, the cytotoxic activity of the tested compounds on human colon carcinoma cells, hepatic cellular carcinoma cells and breast carcinoma cells has been examined From these results it was found that the investigated complexes have effective cytotoxicity against growth of carcinoma cells with respect of its imine ligand
TL;DR: In this article, a landslide hazard evaluation and zonation (LHZ) was carried out in Jeldu District in Central Ethiopia, about 156 km West of Addis Ababa, the capital city of Ethiopia.
Abstract: In the present study landslide hazard evaluation and zonation (LHZ) was carried out in Jeldu District in Central Ethiopia, about 156 km West of Addis Ababa, the capital city of Ethiopia. Through field based inventory mapping and image interpretation 34 past landslides were mapped in the study area. The governing factors; aspect, slope and elevation, were determined from the digital elevation model (DEM), which was obtained from the ASTER satellite. Lithology was adopted from the geological map of Ethiopia (1:2,000,000), while the soil and land use/land cover were processed from Landsat + ETM satellite data. All governing factors were statistically analyzed to find the correlation with the past landslides. In this study, statistical – probabilistic approach was used to rate the governing factors and then customized raster calculation was made in GIS environment to develop the LHZ map. The results revealed that 12% (5.64 km 2 ) of the study area falls under no hazard, 27% (12.69 km 2 ) as low hazard, 32% (15.04 km 2 ) as moderate hazard, 21% (9.87 km 2 ) as high hazard and the rest 8% (3.76 km 2 ) as very high hazard. The validation of LHZ map shows that, 92% of past landslides fall in high or very high hazard zones, while 6% fall in medium and only 2% in low landslide hazard zones. The validation of LHZ map thus, reasonably showed that the adopted methodology produced satisfactory results and the delineated hazard zones may practically be applied for the regional planning and development of infrastructures in the area.
TL;DR: A comprehensive review on governing parameters and various stability analysis techniques for plane mode of failure in rock slopes is presented in this paper, which can be broadly classified as conventional and numerical methods.
Abstract: In stratified sedimentary and meta-sedimentary rock formations ‘plane mode’ of rock failure is very common. The plane failure occurs when a structural discontinuity plane such as; bedding plane, fault plane or preferred orientations of a joint set dips or daylight towards the valley or excavation at an angle smaller than the slope angle and greater than the angle of friction of the discontinuity surface. The stability of the slope, having plane mode of failure, depends on the geometry, rock type, potential failure plane characteristics, groundwater conditions, dynamic loading and the surcharge conditions. The slope may demonstrate these conditions in a simple uniform manner or there may be complex conditions owing to variability in the slope geometry and heterogeneity in the slope material. The stability of the slope, having plane mode of failure, can be assessed by different methods which can be broadly classified as conventional and numerical methods. Conventional methods include; kinematic methods, empirical methods, limit equilibrium and probabilistic methods, whereas numerical methods include continuum, discontinuum and hybrid methods. Each of these methods has their own advantage and limitations owing to the slope conditions, application requirement and capability of an expert. In this paper a comprehensive review on governing parameters and various stability analysis techniques for plane mode of failure in rock slopes is presented.
TL;DR: In this paper, the authors explored the dyeing ability of anthraquinone colorants extracted from Rubia cordifolia lin. roots and proposed a sustainable approach for textile dyeing with a systematic protocol is followed with the effect of AlCl3 and CaCl2 metallic mordants.
Abstract: The present study is aimed to explore the dyeing ability of anthraquinone colorants extracted from Rubia cordifolia Lin. roots. Sustainable approach for textile dyeing with a systematic protocol is followed with the effect of AlCl3 and CaCl2 metallic mordants. The optimization of extraction and dyeing conditions was assessed by Reflectance Spectrophotometry. The optimum extraction and dyeing conditions were found to be pH = 2, time = 45 min and temperature 90 °C and pH = 4, time = 90 min and temperature 90 °C respectively. At optimized conditions, dyeing abilities of pre-mordanted with metallic salts as anchoring agent (AlCl3 and CaCl2) were compared. Wool samples dyed with Madder root extract impart radiant red shades with or without mordants having different hue and tones with commercially acceptable colorimetric and fastness properties without sacrificing much of the resources. Effective improvement in color as well as fastness properties was observed using anchoring agents.
TL;DR: In this paper, a new correlation for calculating the effective viscosity of nanofluids is developed, which is based on the effect of interfacial layer on the nanoparticle, and 75% of them are within the correlation coefficient 078-1 and mean deviation less than 5% of the variance.
Abstract: The development of nanofluid as an innovative class of thermal fluid subsequently inspired use in their engineering applications As a result, the necessity of experimental work to determine the thermophysical properties of nanofluids affecting heat transfer such as specific heat capacity, viscosity, thermal conductivity and density Theoretical models are used in numerical studies of engineering applications to calculate thermophysical properties This study intends to develop a new correlation for calculating the effective viscosity of nanofluids In the model, we considered an effect of interfacial layer on the nanoparticle, the interfacial layer on nanoparticle works as a solid like layer in between the base fluid and nanoparticle surface When nanoparticles are suspended in the base fluid, Brownian motion occurs due to the relative velocity of the base fluid and nanoparticles, which is also incorporated in this model The correlation developed successfully express in outcome advance the viscosity of a variety of nanofluids, (Al 2 O 3 , Fe, hexagonal boron nitride (hBN), ZnO)-Ethylene Glycol, (Al 2 O 3 , hBN, SiC)-Ethylene Glycol Water mixture, (CuO, Al 2 O 3 , Fe 3 O 4 , TiO 2 , hBN, Graphite, Single-wall carbon nanotube (SWCNT))-water, (Fe 3 O 4 )-Toluene The new correlation was derived from 501 viscosity values of nanofluid, 75% of them are within the correlation coefficient 078–1 and mean deviation less than 5%
TL;DR: In this article, an eutectic Zn-3Mg alloy was homogenized at 370°C for 15h and quenched in water before subjected to 2 steps ECAP process.
Abstract: Zn-based alloys have been studied as new biodegradable metals owing to its slower corrosion rate compared to Mg-based alloys and its high potential for mechanical properties improvement. The present work attempts to improve mainly the mechanical properties of a eutectic Zn-3Mg alloy via equal channels angular pressing (ECAP). Cast Zn-3Mg alloy was homogenized at 370 °C for 15 h and quenched in water before subjected to 2 steps ECAP process. Results showed that the process decreases the alloy’s grain size from 48 µm in the as cast to 1.8 µm after 2-passes of ECAP. A remarkably increase of yield strength, tensile strength and elongation was achieved from 65 MPa, 84 MPa and 1.3% (as cast) to 205 MPa, 220 MPa and 6.3% (2-ECAP), respectively. Corrosion rate of the alloy was fairly altered from 0.30 mm/year (as cast) to 0.24 mm/year (2-ECAP). The combination of homogenization and ECAP is therefore viewed as a potential process to improve mechanical properties of Zn-Mg alloys.
TL;DR: A novel and promising PHA-producing bacterial strain is reported as an additional effort to enhance the viability of a sustainable industry based on biofuels and biopolymers.
Abstract: A new bacterial strain was isolated from Atlantic rainforest in Brazil for polyhydroxyalkanoate (PHA) production utilizing crude glycerol from biodiesel industry (CG) and it was identified as Pandoraea sp. MA03. Shake flask experiments were performed at 10–50 g L −1 carbon source and showed the best values of poly(3-hydroxybutyrate) (P3HB) production from CG cultivations compared to pure glycerol, with a polymer accumulation ranging from 49.0% to 63.6% cell dry weight (CDW). The results obtained from this study showed a positive effect of contaminant NaCl on P3HB synthesis up to 30 g L −1 CG. Poly(3-hydroxybutyrate- co -3-hydroxyvalerate) [P(3HB- co -3HV)] production was obtained from CG plus propionic acid with up to 25.9 mol% 3HV. Since it is interesting the utilization of CG for obtaining added-value products along with biodiesel, this study reported a novel and promising PHA-producing bacterial strain as an additional effort to enhance the viability of a sustainable industry based on biofuels and biopolymers.
TL;DR: Two-mode KdV (TMKdV) was introduced in this article, which represents the propagation of two-wave modes in the same direction simultaneously, and a finite series of degree n in terms of a Jacobi elliptic function was suggested as a possible solution for the TMKDV.
Abstract: In this paper we introduce a new type of KdV equations called Two-mode KdV (TMKdV). This equation represents the propagation of two-wave modes in the same direction simultaneously. We suggest a finite series of degree n in terms of a Jacobi elliptic functions as a possible solution for the TMKdV. We succeeded in obtaining new solutions of type solitons and periodics.
TL;DR: These methods have proven suitable to optimize cellulase production by a thermophilic Bacillus by using response surface methodology (RSM) and 3 fold increase in cellul enzyme production was achieved by RSM model.
Abstract: Cellulase shows great interest in the field of organic acids, and biotechnology industries. Cellulase-producing thermophilic bacteria was isolated from West Coast hot spring (Rajapur, Ratnagiri District of Maharashtra (Lat. 16°38′42″N; long. 73°31′53″E) and identified as Bacillus licheniformis. Out of seven variables in the cellulase production medium, four variables such as carboxy methyl cellulose (CMC), calcium chloride, Tween-20, and temperature were screened through Plackett–Burman design and further optimized through response surface methodology (RSM) for higher cellulase production. The optimal conditions were found to be CMC, 19.21 g/L, CaCl2·6H2O, 25.06 mg/L, Tween-20, 2.96 mL/L and temperature 43.35 °C. The high cellulase production 42.99 IU/mL was achieved in a 7 L scale bio fermenter using optimal conditions. A 3 fold increase in cellulase production was achieved by RSM model. These methods have proven suitable to optimize cellulase production by a thermophilic Bacillus.
TL;DR: In this paper, an algorithm for approximating solutions to fractional differential equations (FDEs) in a modified new Bernstein polynomial basis is introduced, where a basic matrix equation which corresponds to a system of fractional equations is utilized, and a new system of nonlinear algebraic equations is obtained.
Abstract: An algorithm for approximating solutions to fractional differential equations (FDEs) in a modified new Bernstein polynomial basis is introduced. Writing x → x α ( 0 α 1 ) in the operational matrices of Bernstein polynomials, the fractional Bernstein polynomials are obtained and then transformed into matrix form. Furthermore, using Caputo fractional derivative, the matrix form of the fractional derivative is constructed for the fractional Bernstein matrices. We convert each term of the problem to the matrix form by means of fractional Bernstein matrices. A basic matrix equation which corresponds to a system of fractional equations is utilized, and a new system of nonlinear algebraic equations is obtained. The method is given with some priori error estimate. By using the residual correction procedure, the absolute error can be estimated. Illustrative examples are included to demonstrate the validity and applicability of the presented technique.
TL;DR: In this paper, the mechanical and tribological properties of various compositions of aluminium 6063 alloy -clay (Al-clay) composites for brake pad applications were studied, and the results of the wear tests as well as the metallographic investigation of optical, scanning electron microscopy and energy dispersive X-ray microscopy revealed an improvement in the tensile strength, hardness and wear resistance in the composites with 10−25% clays.
Abstract: In this paper, the mechanical and tribological behaviours of various compositions of aluminium 6063 alloy – clay (Al-clay) composites for brake pad applications were studied. The Al-clay composites with 5–30 wt% of clay particles of grain size of 60 BSS (250 microns) were developed through stir casting route. The wear characteristics of Al-clay in dry sliding conditions were subjected to a series of Denison T62 HS pin-on-disc wear tests. The action of two different loads (4 and 10 N), three sliding speeds of 200, 500 and 1000 rpm were investigated. The results of the mechanical and wear tests as well as the metallographic investigation of optical, scanning electron microscopy and energy dispersive X-ray microscopy revealed an improvement in the tensile strength, hardness and wear resistance in the composites with 10–25 wt% clays. The best values were obtained at 15 wt%. Wear rate was highly influenced by applied load and sliding speed. The developed composites with 15–25 wt% clay addition were similar to conventional semi metallic brake pad in terms of wear and friction properties.
TL;DR: In this article, the properties of magneto-hydrodynamic boundary layer stagnation point flow of Eyring-Powell (non-Newtonian) fluid induced by an inclined stretching cylindrical surface in the presence of both mixed convection and Joule heating effects are analyzed.
Abstract: The current analysis is carried out to envision the properties of magneto-hydrodynamic boundary layer stagnation point flow of Eyring-Powell (non-Newtonian) fluid induced by an inclined stretching cylindrical surface in the presence of both mixed convection and Joule heating effects. Flow analysis is manifested with temperature stratification phenomena. The strength of temperature adjacent to the cylindrical surface is assumed to be higher in strength as compared to the ambient fluid. A suitable similarity transformations are utilized to convert the flow conducting equations (mathematically modelled) into system of coupled non-linear ordinary differential equations. A fifth order Runge-Kutta algorithm charted with shooting scheme is used to trace out the numerical additions. It was found that the velocity profile is an increasing function of both mixed convection and curvature parameters. Temperature profile show inciting nature towards Eckert number. In addition, a straight line and parabolic curve fitting way of study is executed to inspect the effect logs of mixed convection parameter, magnetic field parameter, thermal stratification parameter and heat generation parameter on skin friction coefficient and heat rate. It seems to be first attempt in this direction and will serve as a facilitating source for the preceding studies regarding fluid rheology.
TL;DR: In this paper, the operational matrix of integration for Laguerre polynomial is used to solve fractional model of Bloch equation in nuclear magnetic resonance (NMR).
Abstract: In present paper operational matrix of integration for Laguerre polynomial is used to solve fractional model of Bloch equation in nuclear magnetic resonance (NMR). The operational matrix converts the Bloch equation in a system of linear algebraic equations. Solving system we obtain the approximate solutions for fractional Bloch equation. Results are compared with existing methods and exact solution. Graphs are plotted for different fractional values of time derivatives.
TL;DR: In this paper, the laws of conservations under the similarity transformation suggested by Wang (1976) have been used to extract a highly nonlinear ordinary differential equation governing the magneto hydrodynamic (MHD) flow.
Abstract: Squeezing flow of an electrically conducting Casson fluid has been taken into account The laws of conservations under the similarity transformation suggested by Wang (1976) have been used to extract a highly nonlinear ordinary differential equation governing the magneto hydrodynamic (MHD) flow Resulting equation has been solved analytically by using the variation of parameters method (VPM) A RK-4 numerical solution has also been sought to examine the validity of analytical results Both the solutions are found to be in an excellent agreement Convergence of the solution is also discussed Flow behavior under the modifying involved physical parameters is also discussed and explained in detail with the graphical aid It is observed that magnetic field can be used as a control phenomenon in many flows as it normalizes the flow behavior Also, squeeze number plays an important role in these types of problems and an increase in squeeze number increases the velocity profile
TL;DR: In this article, thermal stratification and suction/injection effects on the entropy generation and heat transfer due to convective boundary layer flow over a vertical stretching cylinder using Buongiorno's model for nanofluids were discussed.
Abstract: This paper discusses the thermal stratification and suction/injection effects on the entropy generation and heat transfer due to convective boundary layer flow over a vertical stretching cylinder using Buongiorno’s model for nanofluids. For the nanoparticle volume fraction, the boundary conditions are taken such that its normal fluxes are zero. The governing equations and the entropy equation are derived in cylindrical coordinates, in details. Similar transformations are used to convert the governing equation into ordinary differential equations and the resulting system is solved numerically using MATLAB function bvp4c. The obtained results are presented in terms of velocity profiles, temperature distributions, nanoparticle volume fraction, local entropy generation, skin friction coefficient and local Nusselt number. It is found that the minimum values of the entropy generation occur in the injection case, while the suction case maximizes the entropy generation. The increase in the thermal stratification parameter decreases the profiles of velocity temperature and nanoparticle volume fraction, while it enhances the entropy generation.