The objective of this work is to examine how temperature-dependent thermal conductivity and concentration-dependent molecular diffusion affect Reiner-Philippoff nanofluid flow past a nonlinear stretching sheet. At the...The objective of this work is to examine how temperature-dependent thermal conductivity and concentration-dependent molecular diffusion affect Reiner-Philippoff nanofluid flow past a nonlinear stretching sheet. At the interface of the elongated surface zero-mass flux and melting heat condition are incorporated. The formulated mathematical problem is simplified by implementing suitable similarity transformations. For the numerical solution bvp4c is utilized. The parameters emerging in the model are discussed versus allied profiles through graphical illustrations. It is perceived that the velocity of the fluid decays on incrementing the Bingham number. The gyrotactic microorganism profile declines on amplifying the Peclet number. The validation of the proposed model is also added to this study. .展开更多
In this paper,we discussed the effect of nanoparticles shape on bioconvection nanofluid flow over the vertical cone in a permeable medium.The nanofluid contains water,Al2O3 nanoparticles with sphere(spherical)and lami...In this paper,we discussed the effect of nanoparticles shape on bioconvection nanofluid flow over the vertical cone in a permeable medium.The nanofluid contains water,Al2O3 nanoparticles with sphere(spherical)and lamina(non-spherical)shapes and motile microorganisms.The phenomena of heat absorption/generation,Joule heating and thermal radiation with chemical reactions have been incorporated.The similarity transformations technique is used to transform a governing system of partial differential equations into ordinary differential equations.The numerical bvp4c MATLAB program is used to find the solution of ordinary differential equations.The interesting aspects of pertinent parameters on mass transfer,energy,concentration,and density of themotilemicroorganisms’profiles are computed and discussed.Our analysis depicts that the performance of sphere shape nanoparticles in the form of velocity distribution,temperature distribution,skin friction,Sherwood number and Motile density number is better than lamina(non-spherical)shapes nanoparticles.展开更多
Magnetohydrodynamic (MHD) bioconvection of an incompressible electrically conducting nanofluid near a vertical wavy surface saturated porous medium containing both nanoparticle and gyrotactic microorganisms is inves...Magnetohydrodynamic (MHD) bioconvection of an incompressible electrically conducting nanofluid near a vertical wavy surface saturated porous medium containing both nanoparticle and gyrotactic microorganisms is investigated. The nanofluid is represented by a model that includes both Brownian motion and thermophoresis effects. A suitable set of non-dimensional variables are used to transform the governing boundary layer equations into a dimensionless form. The resulting nonlinear system is mapped to the vertical flat plate domain, and a non-similar solution is used to the obtained equations. The obtained non-similar system is then solved numerically using the fourth-order Runge-Kutta method. The influence of various physical parameters on the local Nusselt number, the local Sherwood number, the local density number of the motile microorganisms, the dimensionless velocity, the dimensionless temperature, and the rescaled density of motile microorganisms is studied. It is found that the local Nusselt number, the local Sherwood number, and the local density number of the motile microorganisms decrease by increasing either the Grashof number or the magnetic field parameter.展开更多
Analysis of a gravity-induced film flow of a fluid containing both nanoparticles and gyrotactic microorganisms along a convectively heated vertical surface is presented.The Buongiorno model is applied. Two kinds of bo...Analysis of a gravity-induced film flow of a fluid containing both nanoparticles and gyrotactic microorganisms along a convectively heated vertical surface is presented.The Buongiorno model is applied. Two kinds of boundary conditions, the passive and the active boundary conditions, are considered to investigate this film flow phenomenon.Through a set of similarity variables, the ordinary differential equations that describe the conservation of the momentum, the thermal energy, the nanoparticles, and the microorganisms are derived and then solved numerically by an efficient finite difference technique.The effects of various physical parameters on the profiles of momentum, thermal energy,nanoparticles, microorganisms, local skin friction, local Nusselt number, local wall mass flux, and local wall motile microorganisms flux are investigated. It is expected that the passively controlled nanofluid model can be much more easily achieved and applied in real circumstances than the actively controlled model.展开更多
This study focusses on the numerical investigations of boundary layer flow for magnetohydrodynamic(MHD)and a power-law nanofluid containing gyrotactic microorganisms on an exponentially stretching surface with zero na...This study focusses on the numerical investigations of boundary layer flow for magnetohydrodynamic(MHD)and a power-law nanofluid containing gyrotactic microorganisms on an exponentially stretching surface with zero nanoparticle mass flux and convective heating.The nonlinear system of the governing equations is transformed and solved by Runge-Kutta-Fehlberg method.The impacts of the transverse magnetic field,bioconvection parameters,Lewis number,nanofluid parameters,Prandtl number and power-law index on the velocity,temperature,nanoparticle volume fraction,density of motile microorganism profiles is explored.In addition,the impacts of these parameters on local skin-friction coefficient,local Nusselt,local Sherwood numbers and local density number of the motile microorganisms are discussed.The results reveal that the power law index is considered an important factor in this study.Due to neglecting the buoyancy force term,the bioconvection and nanofluid parameters have slight effects on the velocity profiles.The resultant Lorentz force,from increasing the magnetic field parameter,try to decrease the velocity profiles and increase the rescaled density of motile microorganisms,temperature and nanoparticle volume fraction profiles.Physically,an augmentation of power-law index drops the reduced local skin-friction and reduced Sherwood number,while it increases reduced Nusselt number and reduced local density number of motile microorganisms.展开更多
An accelerated water-streaming test was used to evaluate several roofing materials regarding their behavior to colonization by algae, by closely reproducing the phenomenon of natural biological soiling. A set of roofi...An accelerated water-streaming test was used to evaluate several roofing materials regarding their behavior to colonization by algae, by closely reproducing the phenomenon of natural biological soiling. A set of roofing materials with defined physical and chemical characteristics was thus investigated against the colonization by algae. Porosity, roughness and chemical composition showed to be factors of influence in the establishment of those micro-organisms.展开更多
The mathematical model of bioconvection flow of micropolar fluid through a vertical surface containing nanoparticles and gyrotactic microorganisms is presented in this study. In the study, weak and strong concentratio...The mathematical model of bioconvection flow of micropolar fluid through a vertical surface containing nanoparticles and gyrotactic microorganisms is presented in this study. In the study, weak and strong concentrations of microstructures are explored. In the energy and concentration equations, the Catteneo-Christov diffusion models are used to explain temperature and concentration diffusions with thermal and solutal relaxation durations, respectively. The governing equations describing the fluid flow are transformed and parameterized through similarity variables. The approximate analytical solution is obtained by using Homotopy Analysis Method (HAM). The impacts of relevant parameters on the various distributions are investigated and illustrated. It is discovered that increasing the value of the micropolar parameter results in an increase in the microrotation distribution for strong concentrations of microstructures while decreasing the microrotation distribution for weak concentrations of microstructures.展开更多
A high optical magnification three-dimensional imaging system is proposed using an optic microscope whose ocular (eyepiece) is retained and the structure of the transmission mode is not destroyed. The elemental imag...A high optical magnification three-dimensional imaging system is proposed using an optic microscope whose ocular (eyepiece) is retained and the structure of the transmission mode is not destroyed. The elemental image array is captured through the micro lens array. Due to the front diffuse transmission element, each micro lens sees a slightly different spatial perspective of the scene, and a different independent image is formed in each micro lens channel. Each micro lens channel is imaged by a Fourier lens and captured by a CCD. The design translating the stage in x or y provides no parallax. Compared with the conventional integral imaging of micro-objects, the optical magnification of micro-objects in the proposed system can enhanced remarkably. The principle of the enhancement of the image depth is explained in detail and the experimental results are presented.展开更多
Objective:To investigate the antibacterial activity of henna(Lawsonia inermis Linn) obtained from different regions of Oman against a wide array of micro-organisms.Methods:fresh henna samples were obtained from differ...Objective:To investigate the antibacterial activity of henna(Lawsonia inermis Linn) obtained from different regions of Oman against a wide array of micro-organisms.Methods:fresh henna samples were obtained from different regions of Oman as leaves and seeds,100 g fresh and dry leaves and SO g of fresh and dry seeds were separately soaked in 500 mL of ethanol for three days,respectively,with frequent agitation.The mixture was filtered,and the crude extract was collected.The crude extract was then heated,at 48 ℃ in a water bath to evaporate its liquid content.The dry crude henna extract was then tested for its antibacterial activity using well-diffusion antibiotic susceptibility technique.Henna extracts were investigated for their antibacterial activity at different concentrations against a wide array of different micro-organisms including a laboratory standard bacterial strain of Pseudomonas aeruginosa(NCTC 10662)(A aeruginosa) and eleven fresh clinical isolates of P.aeruginosa obtained from patients attending the Sultan Qaboos University Hospital(SQUH).2-Hydroxy-p-Nathoqinone-Tech(2-HPNT, MW=174.16,C_(10)H_40_3) was included as control(at 50%concentration) along with the henna samples tested.Results:Henna samples demonstrated antibacterial activity against all isolates but the highest susceptibility was against P.aeruginosa with henna samples obtained from Al-sharqyia region.Conclusions:Omani henna from Al-sharqyia region demonstrates high in vitro anti-P. aeruginosa activity compared with many henna samples from different regions of Oman.展开更多
基于趋旋性微生物和幂律流体模型,研究了在含有非 Newton 流体饱和多孔介质中生物对流的线性稳定性问题.利用 Galerkin 数值方法求解了该系统的控制方程,得到生物Rayleigh 数的数值解,讨论了非 Newton 流体的幂律指数对生物对流稳定性...基于趋旋性微生物和幂律流体模型,研究了在含有非 Newton 流体饱和多孔介质中生物对流的线性稳定性问题.利用 Galerkin 数值方法求解了该系统的控制方程,得到生物Rayleigh 数的数值解,讨论了非 Newton 流体的幂律指数对生物对流稳定性在假塑性流体和膨胀性流体间的变化规律.研究结果表明,随着幂律流体的速度增大,幂律指数对生物对流稳定性的影响会发生变化,并且这种变化会受到热Rayleigh 数和生物 Lewis 数的影响.另外,微生物趋旋性特征越明显,生物对流系统就越不稳定,而适当增大非 Newton 流体的幂律指数则有利于系统的稳定性.展开更多
The aim of this study is to investigate the effect of different additives including biochar, effective micro-organisms (EM), animal manure and commercial microbial inoculants on the bioconversion of rice straw. Differ...The aim of this study is to investigate the effect of different additives including biochar, effective micro-organisms (EM), animal manure and commercial microbial inoculants on the bioconversion of rice straw. Different compost piles were constructed, and each contained 50 kg of rice straw and mixture of natural rocks to enrich the compost nutritional value. The physical, chemical and biological parameters indicating the decomposition of organic material, maturation and quality of the organic fertilizer product were investigated during the composting process. A rapid increase in compost temperature was obtained in inoculated piles. All piles reached maturation after around 42 days. All analysis of the properties of the final compost products indicated that it was in the range of the matured level and can be used as organic fertilizer without limitation. The highest decomposition rate and highest organic fertilizer quality were obtained in the pile inoculated with EM and 10% biochar compared to other treatments.展开更多
In this paper, the three-dimensional nanofluid bio-convection near a stagnation attachment is studied. With a set of similarity variables, the governing equations embodying the conservation of total mass, momentum, th...In this paper, the three-dimensional nanofluid bio-convection near a stagnation attachment is studied. With a set of similarity variables, the governing equations embodying the conservation of total mass, momentum, thermal energy, nanoparticles and microorganisms are reduced to a set of fully coupled nonlinear differential equations. The homotopy analysis method (HAM)-finite difference method (FDM) technique is used to obtain exact solutions. The effect of various physical parameters on distribution of the motile microorganisms and the important physical quantities of practical interests are presented and discussed.展开更多
We study the propulsion matrix of bacterial flagella numerically using slender body theory and the regularized Stokeslet method in a biologically relevant parameter regime. All three independent elements of the matrix...We study the propulsion matrix of bacterial flagella numerically using slender body theory and the regularized Stokeslet method in a biologically relevant parameter regime. All three independent elements of the matrix are measured by computing propulsive force and torque generated by a rotating flagellum, and the drag force on a translating flagellum. Nu- merical results are compared with the predictions of resistive force theory, which is often used to interpret micro-organism propulsion. Neglecting hydrodynamic interactions between different parts of a flagellum in resistive force theory leads to both qualitative and quantitative discrepancies between the theoretical prediction of resistive force theory and the numerical results. We improve the original theory by empirically incorporating the effects of hydrodynamic interactions and propose new expressions for propulsive matrix elements that are accurate over the parameter regime explored.展开更多
This paper presents a two-dimensional unsteady laminar boundary layer mixed convection flow heat and mass transfer along a vertical plate filled with Casson nanofluid located in a porous quiescent medium that contains...This paper presents a two-dimensional unsteady laminar boundary layer mixed convection flow heat and mass transfer along a vertical plate filled with Casson nanofluid located in a porous quiescent medium that contains both nanoparticles and gyrotactic microorganisms. This permeable vertical plate is assumed to be moving in the same direction as the free stream velocity. The flow is subject to a variable heat flux, a zero nanoparticle flux and a constant density of motile microorganisms on the surface. The free stream velocity is time-dependent resulting in a non-similar solution. The transport equations are solved using the bivariate spectral quasilinearization method. A grid independence test for the validity of the result is given. The significance of the inclusion of motile microorganisms to heat transfer processes is discussed. We show, inter alia, that introducing motile microorganisms into the flow reduces the skin friction coefficient and that the random motion of the nanoparticles improves the rate of transfer of the motile microorganisms.展开更多
Bioconvection has shown significant promise for environmentally friendly,sustainable“green”fuel cell technologies.The improved design of such systems requires continuous refinements in biomatheatical modeling in con...Bioconvection has shown significant promise for environmentally friendly,sustainable“green”fuel cell technologies.The improved design of such systems requires continuous refinements in biomatheatical modeling in conjunction with laboratory and fieldtesting.Motivated by exploring deeper the near-wall transport phenomena involved inbio-inspired fuel cells,in the present paper,we examine analytically and numericallythe combined free-forced convective steady boundary layer flow from a solid verticalflat plate embedded in a Darcian porous medium containing gyrotactic microorganisms.Gyrotaxis is one of the many taxes exhibited in biological microscale transport,andother examples include magneto-taxis,photo-taxis,chemotaxis and geo-taxis (reflecting the response of microorganisms to magnetic field,light,chemical concentration orgravity,respectively). The bioconvection fuel cell also contains difusing oxygen specicswhich mimics the cathodic behavior in a proton exchange membrane(PEM) systei.Thevertical wall is maintained at isosolutal (constant oxygen volume fraction and motilemicroorganism density) and iso-thermal conditions. Wall values of these quantities aresustained at higher values than the ambient temperature and concentration of oxygenand biological microorganism specics.Similarity transformations are applied to renderthe governing partial differential equations for mass,momentum,energy,oxygen speciesand microorganism species density into a system of ordinary differential equations. Theemerging eight order nonlinear coupled,ordinary differential boundary value problemfeatures several important dimensionless control parameters,namely Lewis number(Le),buoyancy ratio paraneter i.e. ratio of oxygen species buoyancy force to thermal buoy-ancy force(Nr), bioconvection Rayleigh number(Rb), bioconvection Lewis number(Lb),bioconvection Peclet number(Pe) and the mixed convection parameter(e) spanning theentire range of free and forced convection. The transformed nonlinear system of equationswith boundary conditions is solved numerically by a finite difference met.hod with centraldifferencing,tridiagonal matrix manipulation and an iterative procedure.Computationsare validated with the symbolic Maple 14.0 software.The influence of buoyancy andbioconvection parameters on the dimensionless temperature,velocity,oxygen concentration and motile microorganism density distribution,Nusselt,Sherwood and gradient ofmotile microorganism density are studied. The work clearly shows the benefit of utilizingbiological organisms in fuel cell design and presents a logical biomathematical modeling framework for simulating such systems.In particular,the deployment of gyrotacticmicroorganisns is shown to stimulate improved transport characteristics in heat andmormentum at the fuel cell wall.展开更多
The waste management is a major environmental challenge in all the countries. In the Republic of Benin, in absence of controlled landfill, the wetlands are filling in by solid household waste to set up housing environ...The waste management is a major environmental challenge in all the countries. In the Republic of Benin, in absence of controlled landfill, the wetlands are filling in by solid household waste to set up housing environments. This study aimed at identifying the various forms of wetlands water pollutions originated by this practice. Physico-chemical parameters of sampling water were determined by using Ionic chromatography and spectrometry of atomic absorption. The microorganisms indicating fecal peril were identified by the conventional techniques of microbiology. Water quality of a witness well was also used to assess the general water quality of the backfilled wetland. The results revealed the water samples collected from backefilled wetlands were mineralized (898.32 ± 6.13 μs/cm), rich in chlorinate (237.80 ± 4.23 mg/L) and nitrates ions (224.10 ± 3.42 mg/L). They are more colored (399.23 ± 3.01 Pt/Co) and more turbid (62.5 ± 2.48 NTU) than those of the unfilled wetlands. The results of microbiological analysis shown the presence of the cysts of <em>Giardia lamblia</em> (590/100 L) and cysts of <em>Entamoeba histolytica</em> (13/100 L) in all water, except those of witness well. The frequency of water contamination by bacteria indicating general degradation is 86.4%. The embankment of the wetlands by the solid household waste leads to the water pollution.展开更多
The current article investigates the impact of the bioconvection in an unsteady flow of magnetized Cross nanofluid with gyrotactic microorganisms and activation energy over a linearly stretched configuration.The analy...The current article investigates the impact of the bioconvection in an unsteady flow of magnetized Cross nanofluid with gyrotactic microorganisms and activation energy over a linearly stretched configuration.The analysis has been performed by utilizing the realistic Wu's slip boundary and zero mass flux conditions.The effects of nonlinear thermal radiation and the activation energy are also addressed.The governing flow equations are deduced to a dimensionless form by considering suitable transformations which are numerically targeted via a shooting algorithm.The physical visualization of each physical parameter governing the flow problem has been displayed graphically for distribution of velocity,temperature,concentration and motile microorganisms.The numerical treatment for the variation of skin friction coefficient,local Nusselt number,local Sherwood number and motile density number is performed in tabular forms.展开更多
文摘The objective of this work is to examine how temperature-dependent thermal conductivity and concentration-dependent molecular diffusion affect Reiner-Philippoff nanofluid flow past a nonlinear stretching sheet. At the interface of the elongated surface zero-mass flux and melting heat condition are incorporated. The formulated mathematical problem is simplified by implementing suitable similarity transformations. For the numerical solution bvp4c is utilized. The parameters emerging in the model are discussed versus allied profiles through graphical illustrations. It is perceived that the velocity of the fluid decays on incrementing the Bingham number. The gyrotactic microorganism profile declines on amplifying the Peclet number. The validation of the proposed model is also added to this study. .
文摘In this paper,we discussed the effect of nanoparticles shape on bioconvection nanofluid flow over the vertical cone in a permeable medium.The nanofluid contains water,Al2O3 nanoparticles with sphere(spherical)and lamina(non-spherical)shapes and motile microorganisms.The phenomena of heat absorption/generation,Joule heating and thermal radiation with chemical reactions have been incorporated.The similarity transformations technique is used to transform a governing system of partial differential equations into ordinary differential equations.The numerical bvp4c MATLAB program is used to find the solution of ordinary differential equations.The interesting aspects of pertinent parameters on mass transfer,energy,concentration,and density of themotilemicroorganisms’profiles are computed and discussed.Our analysis depicts that the performance of sphere shape nanoparticles in the form of velocity distribution,temperature distribution,skin friction,Sherwood number and Motile density number is better than lamina(non-spherical)shapes nanoparticles.
文摘Magnetohydrodynamic (MHD) bioconvection of an incompressible electrically conducting nanofluid near a vertical wavy surface saturated porous medium containing both nanoparticle and gyrotactic microorganisms is investigated. The nanofluid is represented by a model that includes both Brownian motion and thermophoresis effects. A suitable set of non-dimensional variables are used to transform the governing boundary layer equations into a dimensionless form. The resulting nonlinear system is mapped to the vertical flat plate domain, and a non-similar solution is used to the obtained equations. The obtained non-similar system is then solved numerically using the fourth-order Runge-Kutta method. The influence of various physical parameters on the local Nusselt number, the local Sherwood number, the local density number of the motile microorganisms, the dimensionless velocity, the dimensionless temperature, and the rescaled density of motile microorganisms is studied. It is found that the local Nusselt number, the local Sherwood number, and the local density number of the motile microorganisms decrease by increasing either the Grashof number or the magnetic field parameter.
基金Project supported by the Program for New Century Excellent Talents in University(No.NCET-12-0347)
文摘Analysis of a gravity-induced film flow of a fluid containing both nanoparticles and gyrotactic microorganisms along a convectively heated vertical surface is presented.The Buongiorno model is applied. Two kinds of boundary conditions, the passive and the active boundary conditions, are considered to investigate this film flow phenomenon.Through a set of similarity variables, the ordinary differential equations that describe the conservation of the momentum, the thermal energy, the nanoparticles, and the microorganisms are derived and then solved numerically by an efficient finite difference technique.The effects of various physical parameters on the profiles of momentum, thermal energy,nanoparticles, microorganisms, local skin friction, local Nusselt number, local wall mass flux, and local wall motile microorganisms flux are investigated. It is expected that the passively controlled nanofluid model can be much more easily achieved and applied in real circumstances than the actively controlled model.
基金the Deanship of Scientific Research at King Khalid University for funding this work through Big Group Research Project under grant number(R.G.P2/16/40).
文摘This study focusses on the numerical investigations of boundary layer flow for magnetohydrodynamic(MHD)and a power-law nanofluid containing gyrotactic microorganisms on an exponentially stretching surface with zero nanoparticle mass flux and convective heating.The nonlinear system of the governing equations is transformed and solved by Runge-Kutta-Fehlberg method.The impacts of the transverse magnetic field,bioconvection parameters,Lewis number,nanofluid parameters,Prandtl number and power-law index on the velocity,temperature,nanoparticle volume fraction,density of motile microorganism profiles is explored.In addition,the impacts of these parameters on local skin-friction coefficient,local Nusselt,local Sherwood numbers and local density number of the motile microorganisms are discussed.The results reveal that the power law index is considered an important factor in this study.Due to neglecting the buoyancy force term,the bioconvection and nanofluid parameters have slight effects on the velocity profiles.The resultant Lorentz force,from increasing the magnetic field parameter,try to decrease the velocity profiles and increase the rescaled density of motile microorganisms,temperature and nanoparticle volume fraction profiles.Physically,an augmentation of power-law index drops the reduced local skin-friction and reduced Sherwood number,while it increases reduced Nusselt number and reduced local density number of motile microorganisms.
文摘An accelerated water-streaming test was used to evaluate several roofing materials regarding their behavior to colonization by algae, by closely reproducing the phenomenon of natural biological soiling. A set of roofing materials with defined physical and chemical characteristics was thus investigated against the colonization by algae. Porosity, roughness and chemical composition showed to be factors of influence in the establishment of those micro-organisms.
文摘The mathematical model of bioconvection flow of micropolar fluid through a vertical surface containing nanoparticles and gyrotactic microorganisms is presented in this study. In the study, weak and strong concentrations of microstructures are explored. In the energy and concentration equations, the Catteneo-Christov diffusion models are used to explain temperature and concentration diffusions with thermal and solutal relaxation durations, respectively. The governing equations describing the fluid flow are transformed and parameterized through similarity variables. The approximate analytical solution is obtained by using Homotopy Analysis Method (HAM). The impacts of relevant parameters on the various distributions are investigated and illustrated. It is discovered that increasing the value of the micropolar parameter results in an increase in the microrotation distribution for strong concentrations of microstructures while decreasing the microrotation distribution for weak concentrations of microstructures.
基金Supported by the Scientific Research Fund Project of the Education Department of Shaanxi Province under Grant No 15JK1732the Natural Science Foundation of Shaanxi Province under Grant No2014JQ1044the Science Foundation of Northwest University under Grant No 12NW01
文摘A high optical magnification three-dimensional imaging system is proposed using an optic microscope whose ocular (eyepiece) is retained and the structure of the transmission mode is not destroyed. The elemental image array is captured through the micro lens array. Due to the front diffuse transmission element, each micro lens sees a slightly different spatial perspective of the scene, and a different independent image is formed in each micro lens channel. Each micro lens channel is imaged by a Fourier lens and captured by a CCD. The design translating the stage in x or y provides no parallax. Compared with the conventional integral imaging of micro-objects, the optical magnification of micro-objects in the proposed system can enhanced remarkably. The principle of the enhancement of the image depth is explained in detail and the experimental results are presented.
基金Supported by Sultan Qaboos University(Grant No.IG/MED/ANAT/06/01)
文摘Objective:To investigate the antibacterial activity of henna(Lawsonia inermis Linn) obtained from different regions of Oman against a wide array of micro-organisms.Methods:fresh henna samples were obtained from different regions of Oman as leaves and seeds,100 g fresh and dry leaves and SO g of fresh and dry seeds were separately soaked in 500 mL of ethanol for three days,respectively,with frequent agitation.The mixture was filtered,and the crude extract was collected.The crude extract was then heated,at 48 ℃ in a water bath to evaporate its liquid content.The dry crude henna extract was then tested for its antibacterial activity using well-diffusion antibiotic susceptibility technique.Henna extracts were investigated for their antibacterial activity at different concentrations against a wide array of different micro-organisms including a laboratory standard bacterial strain of Pseudomonas aeruginosa(NCTC 10662)(A aeruginosa) and eleven fresh clinical isolates of P.aeruginosa obtained from patients attending the Sultan Qaboos University Hospital(SQUH).2-Hydroxy-p-Nathoqinone-Tech(2-HPNT, MW=174.16,C_(10)H_40_3) was included as control(at 50%concentration) along with the henna samples tested.Results:Henna samples demonstrated antibacterial activity against all isolates but the highest susceptibility was against P.aeruginosa with henna samples obtained from Al-sharqyia region.Conclusions:Omani henna from Al-sharqyia region demonstrates high in vitro anti-P. aeruginosa activity compared with many henna samples from different regions of Oman.
文摘基于趋旋性微生物和幂律流体模型,研究了在含有非 Newton 流体饱和多孔介质中生物对流的线性稳定性问题.利用 Galerkin 数值方法求解了该系统的控制方程,得到生物Rayleigh 数的数值解,讨论了非 Newton 流体的幂律指数对生物对流稳定性在假塑性流体和膨胀性流体间的变化规律.研究结果表明,随着幂律流体的速度增大,幂律指数对生物对流稳定性的影响会发生变化,并且这种变化会受到热Rayleigh 数和生物 Lewis 数的影响.另外,微生物趋旋性特征越明显,生物对流系统就越不稳定,而适当增大非 Newton 流体的幂律指数则有利于系统的稳定性.
文摘The aim of this study is to investigate the effect of different additives including biochar, effective micro-organisms (EM), animal manure and commercial microbial inoculants on the bioconversion of rice straw. Different compost piles were constructed, and each contained 50 kg of rice straw and mixture of natural rocks to enrich the compost nutritional value. The physical, chemical and biological parameters indicating the decomposition of organic material, maturation and quality of the organic fertilizer product were investigated during the composting process. A rapid increase in compost temperature was obtained in inoculated piles. All piles reached maturation after around 42 days. All analysis of the properties of the final compost products indicated that it was in the range of the matured level and can be used as organic fertilizer without limitation. The highest decomposition rate and highest organic fertilizer quality were obtained in the pile inoculated with EM and 10% biochar compared to other treatments.
基金supported by the Program for New Century Excellent Talents in University of China(No.NCET-12-0347)
文摘In this paper, the three-dimensional nanofluid bio-convection near a stagnation attachment is studied. With a set of similarity variables, the governing equations embodying the conservation of total mass, momentum, thermal energy, nanoparticles and microorganisms are reduced to a set of fully coupled nonlinear differential equations. The homotopy analysis method (HAM)-finite difference method (FDM) technique is used to obtain exact solutions. The effect of various physical parameters on distribution of the motile microorganisms and the important physical quantities of practical interests are presented and discussed.
基金supported by the National Natural Science Foundation of China(Grant No.11104179)the Shanghai Pujiang Program,China(Grant No.12PJ1405400)+1 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,China(Grant No.SHDP201301)the Innovation Program of Shanghai Municipal Education Commission,China(Grant No.14ZZ030)
文摘We study the propulsion matrix of bacterial flagella numerically using slender body theory and the regularized Stokeslet method in a biologically relevant parameter regime. All three independent elements of the matrix are measured by computing propulsive force and torque generated by a rotating flagellum, and the drag force on a translating flagellum. Nu- merical results are compared with the predictions of resistive force theory, which is often used to interpret micro-organism propulsion. Neglecting hydrodynamic interactions between different parts of a flagellum in resistive force theory leads to both qualitative and quantitative discrepancies between the theoretical prediction of resistive force theory and the numerical results. We improve the original theory by empirically incorporating the effects of hydrodynamic interactions and propose new expressions for propulsive matrix elements that are accurate over the parameter regime explored.
文摘This paper presents a two-dimensional unsteady laminar boundary layer mixed convection flow heat and mass transfer along a vertical plate filled with Casson nanofluid located in a porous quiescent medium that contains both nanoparticles and gyrotactic microorganisms. This permeable vertical plate is assumed to be moving in the same direction as the free stream velocity. The flow is subject to a variable heat flux, a zero nanoparticle flux and a constant density of motile microorganisms on the surface. The free stream velocity is time-dependent resulting in a non-similar solution. The transport equations are solved using the bivariate spectral quasilinearization method. A grid independence test for the validity of the result is given. The significance of the inclusion of motile microorganisms to heat transfer processes is discussed. We show, inter alia, that introducing motile microorganisms into the flow reduces the skin friction coefficient and that the random motion of the nanoparticles improves the rate of transfer of the motile microorganisms.
文摘Bioconvection has shown significant promise for environmentally friendly,sustainable“green”fuel cell technologies.The improved design of such systems requires continuous refinements in biomatheatical modeling in conjunction with laboratory and fieldtesting.Motivated by exploring deeper the near-wall transport phenomena involved inbio-inspired fuel cells,in the present paper,we examine analytically and numericallythe combined free-forced convective steady boundary layer flow from a solid verticalflat plate embedded in a Darcian porous medium containing gyrotactic microorganisms.Gyrotaxis is one of the many taxes exhibited in biological microscale transport,andother examples include magneto-taxis,photo-taxis,chemotaxis and geo-taxis (reflecting the response of microorganisms to magnetic field,light,chemical concentration orgravity,respectively). The bioconvection fuel cell also contains difusing oxygen specicswhich mimics the cathodic behavior in a proton exchange membrane(PEM) systei.Thevertical wall is maintained at isosolutal (constant oxygen volume fraction and motilemicroorganism density) and iso-thermal conditions. Wall values of these quantities aresustained at higher values than the ambient temperature and concentration of oxygenand biological microorganism specics.Similarity transformations are applied to renderthe governing partial differential equations for mass,momentum,energy,oxygen speciesand microorganism species density into a system of ordinary differential equations. Theemerging eight order nonlinear coupled,ordinary differential boundary value problemfeatures several important dimensionless control parameters,namely Lewis number(Le),buoyancy ratio paraneter i.e. ratio of oxygen species buoyancy force to thermal buoy-ancy force(Nr), bioconvection Rayleigh number(Rb), bioconvection Lewis number(Lb),bioconvection Peclet number(Pe) and the mixed convection parameter(e) spanning theentire range of free and forced convection. The transformed nonlinear system of equationswith boundary conditions is solved numerically by a finite difference met.hod with centraldifferencing,tridiagonal matrix manipulation and an iterative procedure.Computationsare validated with the symbolic Maple 14.0 software.The influence of buoyancy andbioconvection parameters on the dimensionless temperature,velocity,oxygen concentration and motile microorganism density distribution,Nusselt,Sherwood and gradient ofmotile microorganism density are studied. The work clearly shows the benefit of utilizingbiological organisms in fuel cell design and presents a logical biomathematical modeling framework for simulating such systems.In particular,the deployment of gyrotacticmicroorganisns is shown to stimulate improved transport characteristics in heat andmormentum at the fuel cell wall.
文摘The waste management is a major environmental challenge in all the countries. In the Republic of Benin, in absence of controlled landfill, the wetlands are filling in by solid household waste to set up housing environments. This study aimed at identifying the various forms of wetlands water pollutions originated by this practice. Physico-chemical parameters of sampling water were determined by using Ionic chromatography and spectrometry of atomic absorption. The microorganisms indicating fecal peril were identified by the conventional techniques of microbiology. Water quality of a witness well was also used to assess the general water quality of the backfilled wetland. The results revealed the water samples collected from backefilled wetlands were mineralized (898.32 ± 6.13 μs/cm), rich in chlorinate (237.80 ± 4.23 mg/L) and nitrates ions (224.10 ± 3.42 mg/L). They are more colored (399.23 ± 3.01 Pt/Co) and more turbid (62.5 ± 2.48 NTU) than those of the unfilled wetlands. The results of microbiological analysis shown the presence of the cysts of <em>Giardia lamblia</em> (590/100 L) and cysts of <em>Entamoeba histolytica</em> (13/100 L) in all water, except those of witness well. The frequency of water contamination by bacteria indicating general degradation is 86.4%. The embankment of the wetlands by the solid household waste leads to the water pollution.
基金the Deanship of Scientific Research at King Khalid University for funding this work through Research Groups Program under grant number(R.G.P.2/66/40)。
文摘The current article investigates the impact of the bioconvection in an unsteady flow of magnetized Cross nanofluid with gyrotactic microorganisms and activation energy over a linearly stretched configuration.The analysis has been performed by utilizing the realistic Wu's slip boundary and zero mass flux conditions.The effects of nonlinear thermal radiation and the activation energy are also addressed.The governing flow equations are deduced to a dimensionless form by considering suitable transformations which are numerically targeted via a shooting algorithm.The physical visualization of each physical parameter governing the flow problem has been displayed graphically for distribution of velocity,temperature,concentration and motile microorganisms.The numerical treatment for the variation of skin friction coefficient,local Nusselt number,local Sherwood number and motile density number is performed in tabular forms.