In this study,green zinc oxide(ZnO)/polypyrrole(Ppy)/cellulose acetate(CA)film has been synthesized via solvent casting.This film was used as supporting material for glucose oxidase(GOx)to sensitize a glucose biosenso...In this study,green zinc oxide(ZnO)/polypyrrole(Ppy)/cellulose acetate(CA)film has been synthesized via solvent casting.This film was used as supporting material for glucose oxidase(GOx)to sensitize a glucose biosensor.ZnO nanoparticles have been prepared via the green route using olive leaves extract as a reductant.ZnO/Ppy nanocomposite has been synthesized by a simple in-situ chemical oxidative polymerization of pyrrole(Py)monomer using ferric chloride(FeCl3)as an oxidizing agent.The produced materials and the composite films were characterized using X-ray diffraction analysis(XRD),scanning electron microscope(SEM),Fourier transform infrared(FTIR)and thermogravimetric analysis(TGA).Glucose oxidase was successfully immobilized on the surface of the prepared film and then ZnO/Ppy/CA/GOx composite was sputtered with platinum electrode for the current determination at different initial concentrations of glucose.Current measurements proved the suitability and the high sensitivity of the constructed biosensor for the detection of glucose levels in different samples.The performance of the prepared biosensor has been assessed by measuring and comparing glucose concentrations up to 800 ppm.The results affirmed the reliability of the developed biosensor towards real samples which suggests the wide-scale application of the proposed biosensor.展开更多
Essential oils (EOs) are the volatile lipophilic components extracted from plants. Many EOs have demonstrated strong antimicrobial properties when tested in in vitro experiments. The commercial applications of these E...Essential oils (EOs) are the volatile lipophilic components extracted from plants. Many EOs have demonstrated strong antimicrobial properties when tested in in vitro experiments. The commercial applications of these EOs require a suitable formulation constituted by biodegradable compounds that protect them from degradation and evaporation at the same time that allows for a sustained release. The objective of this study was therefore to reduce the rate of evaporation of the oil via microencapsulation. Alginate microspheres (AMSs) were prepared using emulsion extrusion method. The AMSs were hardened with a cross-linking agent, calcium chloride. The effects of the three variables: alginate concentration (0.5% - 8%), the amount of cross-linking agent (0.125% - 2%) and time of cross-linking (5 - 30 min.) on loading capacity and encapsulation efficiency (EE, %) were studied. The effect of the amount of cross-linker was significant on loading capacity (%) and EE (%). The AMSs under the optimized conditions provided loading capacity of 22% - 24% and EE of 90% - 94% based on type of EO. The antifungal activity of vapors of microencapsulated and non-microencapsulated oils were evaluated against two of pathogenic fungi species for stored grains: Aspergillus niger and Fusarium verticillioides. The optimized MSs were observed to have a sustained in vitro release profile (50% of the antifungal activity was maintained at the 8th day of the study). In conclusion, encapsulation in Ca-alginate microspheres may effectively reduce the evaporation rate of essential oils, thus?increase the potential antifungal activity.展开更多
Water contaminated with pathogenic microbes is considered as one of the most common routes for transmitting diseases in human beings.Different methods have been applied for the decontamination of microbes in contamina...Water contaminated with pathogenic microbes is considered as one of the most common routes for transmitting diseases in human beings.Different methods have been applied for the decontamination of microbes in contaminated water.In the current study,an easy to do hydrothermal method has been used for the preparation of TiO_(2)-Ag nanoparticles.The obtained material was characterised using a scanning electron microscope(SEM)and fourier transform infra-red spectroscopy(FTIR).The morphological appearance of the obtained nanoparticles was in the shape of a sphere with a size range of 60-90 nm.The antimicrobial activity of the prepared nanoparticles was tested against several pathogenic bacteria and fungi.The obtained results proved that the nanoparticles succeeded to affect all the tested microbes in the following order:Bacillus cereus ATCC6633>Pseudomonas aeruginosa ATCC9027=Klebsiella pneumoniae ATCC13883>Vibrio cholera ATCC700=Candida albicans ATCC 700=Escherichia coli NCTC10418>Staphylococcus aureus ATCC6538.The minimum inhibitory concentration(MIC)of the prepared nanoparticles varied among the tested microbes at range of 12 mg/ml and 25 mg/ml.These results encourage the application of prepared TiO_(2)-Ag nanoparticles for treatment of microbe-contaminated waters.展开更多
A novel composite carrier of folic acid(FA)-polyethyleneimine(PEI)-ethosome(Eth)(FA-PEI-Eth)was developed for the treatment of cancers through loading and targeting delivery of multidrug(including gene and other drugs...A novel composite carrier of folic acid(FA)-polyethyleneimine(PEI)-ethosome(Eth)(FA-PEI-Eth)was developed for the treatment of cancers through loading and targeting delivery of multidrug(including gene and other drugs)into cancer cells.Physical and chemical property tests were done to prove the grafting of the composite.Gel retardation test was done to determine the optimal ratio of DNA@PEI complex,and cytocompatibility tests and tumor cell uptake tests were done to evaluate the efficiency of the composite.The results demonstrated that the FA-PEI-Eth could effectively deliver a gene and other drugs into tumor cells simultaneously,and suggested that this composite would be a promising carrier in tumor-targeted therapy applications.展开更多
Current investigation has shown that human exposure to aflatoxins is not limited to the administration of contaminated cereals,but water is another possible source.This study was aimed to design easily applicable meth...Current investigation has shown that human exposure to aflatoxins is not limited to the administration of contaminated cereals,but water is another possible source.This study was aimed to design easily applicable method to eliminate aflatoxin B2(AFB2)from contaminated drinking water.Electrospinning has been used for preparation of probiotic-coated polyvinyl alcohol(PVA)and cellulose acetate(CA)nanofibers.Both of these hybrid nanofibers were studied by scanning electron microscopy(SEM)and Fourier-transformed infrared spectroscopy(FT-IR).SEM showed the proper coating of probiotic strains(Kluyveromyces lactis CBS 2359 and Saccharomyces cerevisiae ATCC 9763)on both nanofiber types.Different areas(1-5 cm^(2))of the probiotic-nanofiber hybrid were used to enhance the removal of 20 ng/ml of aflatoxin B2(AFB2)from prepared AFB2-contaminated water over time.Results revealed that a 5 cm^(2) area of probiotic-coated PVA nanofibers can eliminate 97.5% of AFB2 as compared to 87.5%,90.5%,93.5%,and 95.5%,for 1 cm2,2 cm^(2),3 cm^(2),and 4 cm^(2),respectively,while probiotic-coated CA nanofibers were slightly less effective.Nevertheless,the cytotoxicity of probiotics-CA treated water on cultured human fibroblasts was almost 10 times lower than the cytotoxicity recorded in probiotics-PVA treated water.Therefore,results of the current research suggest that probiotics-polymer nanofiber membranes can be used as an extra stage in the water purification system for the treatment of AFB2-contaminated water.展开更多
Many recent studies are concerned with low cost,easy to handle and alternative renewable energy as a feasible solution for the upcoming crisis of energy shortage.Microalgae are unicellular entities the can only depend...Many recent studies are concerned with low cost,easy to handle and alternative renewable energy as a feasible solution for the upcoming crisis of energy shortage.Microalgae are unicellular entities the can only depend on CO_(2),water and solar power to cover their nutritional needs.The current study is concerned with using algal cells in a polymeric hydrogel,as a cheap source of energy for electricity generation.Chlorella vulgaris has been proved to be a promising algal species for electricity generation,as compared with Micractinium reisseri.PVA hydrogel has been used for the immobilization of both algal species in order to protect them from the adverse surrounding conditions in addition to its ability to slowly release the required water molecules according to needs.Under these conditions,C.vulgaris showed the ability to generate 60 mV compared with 15 mV generated by M.reisseri.Scanning electron micrographs showed nano-threads that bind the C.vulgaris cells to each other,indicating the ability of algae to create nanowires that facilitate the electron transfer among algal cells and from cells to the nearest electrode.However,we would expect an increase in the produced potential with simultaneous amendment of environmentally polluted water,such as sewage or waste water.Both of FTIR and raman spectroscopy proved the presence of the characteristic groups of PVA hydrogel and proved the proper integration of the algal cells inside the hydrogel cavities.展开更多
Magnetic alumina nano composite (MANC) was prepared for combination of the adsorption features of nano activated alumina with the magnetic properties of iron oxides to produce a nano magnetic adsorbent, which can be s...Magnetic alumina nano composite (MANC) was prepared for combination of the adsorption features of nano activated alumina with the magnetic properties of iron oxides to produce a nano magnetic adsorbent, which can be separated from the medium by a simple magnetic process after adsorption. MANC was characterized using XRD, SEM, TEM, EDX and surface area (BET). Quantum design SQUID magnetometer was used to study the magnetic measurement. The present study was conducted to evaluate the feasibility of MANC for the removal of cadmium ions from aqueous solutions through batch adsorption technique. The effects of pH, adsorbent dose, temperature, contact time and initial Cd2+ concentration on cadmium ions adsorption were studied. Equilibrium data were fitted to Langmuir, Freundlich and Temkin isotherms. The equilibrium data were best represented by the Langmuir isotherm. The kinetic data were fitted to pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models, and it was found to follow closely the pseudo-second-order model. Thermodynamic parameters were calculated for the Cd2+ ion-MANC system and the positive value of ΔH° showed that the adsorption was endothermic in nature. Furthermore, a single-stage batch adsorber was designed for the removal of Cd2+ ions by MANC based on the equilibrium data obtained.展开更多
A direct synthesis method is introduced to prepare nano-porous silicon-nickel nanocomposite (nPS/Ni) powder for thermal isolation applications. In this paper, we study the thermal stability of nanocomposites consistin...A direct synthesis method is introduced to prepare nano-porous silicon-nickel nanocomposite (nPS/Ni) powder for thermal isolation applications. In this paper, we study the thermal stability of nanocomposites consisting of nanoparticles metal incorporated into the pores of a porous silicon by a very simple method. The nickel element is chemically deposited whereas the nanoparticles are precipitated on the pore surfaces. The (nPS) and (nPS/Ni) nano-materials are thermally measured under nitrogen at temperatures of 40℃ - 1000℃, noticeable, demonstrating better thermal stability of (nPS/Ni) until 900℃ than in the case of (nPS) at 600℃. Then, the improving of the thermal stability of the nPS powder is facilitated using it in many applications of the thermal insulation process.展开更多
A translucent wooden substrate with long-lasting phosphorescence,high photostability and durability,tough surface,ultraviolet protection,high optical transmittance,and superhydrophobicity was developed.This long-lasti...A translucent wooden substrate with long-lasting phosphorescence,high photostability and durability,tough surface,ultraviolet protection,high optical transmittance,and superhydrophobicity was developed.This long-lasting phosphorescent wooden substrate is able to continue emitting light for extended time periods.Lignin-modified wood(LMW)was immobilized with a solution of epoxy resin(ER)and rare-earth doped aluminate(REDA)phosphor nanoparticles(NPs).For an improved dispersion of pigment,REDA was synthesized in a nanoscale particle size,and characterized by transmission electron microscopy(TEM)to indicate a particle size of 8-14 nm.The crystal structure of REDA nanoparticles was also proved by X-ray diffraction(XRD).For an improved production of long-persistent phosphorescent colo rless woods,REDA must be well-dispersed in MAA without aggregation.Absorption and emissio n,as well as decay and lifetime spectra were explored.The morphologies of the wooden substrates with different ratios of REDA were investigated by scanning electron microscopy(SEM),X-ray fluorescence(XRF)analysis,Fourier transform infrared spectra(FT-IR),elemental mapping,and energy-dispersion Xray(EDXA).The phosphorescent woods show changes in color from colorless to green under ultraviolet(UV)irradiation,and to yellowish-green in the dark,as proved by the colorimetric parameters of the CIE Lab system.The afterglow wood samples display an absorbance band at 365 nm and two phosphorescent bands at 431 and 520 nm.Improved UV shielding,photostability,and hydrophobicity were explored.With increasing REDA ratio,both static contact and slide angles are found to improve in the ranges of147.6°-163.6°and 9°-14°,respectively.The long-lasting photoluminescence is optimized at a REDA ratio of 8%.The present strategy shows a large-scale production approach of multiple functional woods for many potential applications,such as smart glow in the dark windows and safety signs.展开更多
The purpose of the present research is the different morphologies production of crystalline and amorphous-silica powder. It’s a basic material for many pharmaceutical and environmental applications as well. And, it’...The purpose of the present research is the different morphologies production of crystalline and amorphous-silica powder. It’s a basic material for many pharmaceutical and environmental applications as well. And, it’s produced using the combination of the alkali chemical etching process and the ultra-sonication technique. The critical preparation conditions are KOH concentration (weight %) and the sonication time (hour). The paper presents the chemical mechanism of the silica particle formation as well as the different morphology. The results show the formation of crystalline and amorphous-porous-silica particles in the micrometer range with the porous order network that has pore sizes range in micrometer too. This synthetic uses commercial silicon, which could be useful for large-scale production. Also, the nano-sphere and nano-cubic shapes of silica powder are formed starting by commercial silicon powder.展开更多
This paper reports the feasibility of synthesis and characterization of nano-porous silicon (NPS) powder and (Nickel/nano-porous silicon, Ni/NPS) nano-composite prepared using dual techniques (alkaline chemical etchin...This paper reports the feasibility of synthesis and characterization of nano-porous silicon (NPS) powder and (Nickel/nano-porous silicon, Ni/NPS) nano-composite prepared using dual techniques (alkaline chemical etching process and ultra-sonication technique). The structural and the optical properties of the fabricated structures are inspected using X-ray Diffraction, Fourier Transform Infrared Spectrophotometer, Raman Spec-troscopy, and Fluorescence Spectrophotometer Photoluminescence. All the results have agreed that NPS is one of the most suitable materials used as active material in the LED fabrication;by changing the main factors in the preparation process, so the different physical and chemical properties are obtained. NPS produces two emission regions that correspond to orange-red and dark red;on the other hand, (Ni/NPS) produce the yellow emission. So, the photoluminescence emission is controllable by adjusting the preparation conditions. The optical data recorded here are useful for the production of the nanoscale optical devices.展开更多
The fabrication of nano porous silicon, nPSi, using alkali etching process has been studied and carried out. The surface chemistry of anisotropic etching of n-type Si-wafer is reviewed and the anisotropic chemical etc...The fabrication of nano porous silicon, nPSi, using alkali etching process has been studied and carried out. The surface chemistry of anisotropic etching of n-type Si-wafer is reviewed and the anisotropic chemical etching of silicon in alkaline solution using wetting agents is discussed. Transformation of crystallographic plane of n-Si (211) to nPSi (100) has occurred on using n-propanol as wetting agent. The rate of pore formation was 0.02478 - 0.02827 μm/min, which was heavily dependent upon the concentration of the etchant containing wetting agents, allowing patterned porous silicon formation through selective doping of the substrate. A particle size of 15 nm for porous nano-silicon was calculated from the XRD data. Porosity of PS layers is about 10%. Pore diameter and porous layer thickness are 0.0614 nm and 16 μm, respectively. The energy gap of the produced porous silicon is 3.3 eV. Furthermore, the combination of PS with Congo Red, which are nanostructured due to their deposition within the porous matrix is discussed. Such nano compounds offer broad avenue of new and interesting properties depending on the involved materials as well as on their morphology. Chemical route was utilized as the host material to achieve pores filling. They were impregnated with Congo Red, which gave good results for the porous silicon as a promising pH sensor.展开更多
Dielectric barrier discharge is used as a cheap technique for surface treatment of polycarbonate. The discharge system is working in open air at atmospheric pressure. The treatments are carried out at low discharge po...Dielectric barrier discharge is used as a cheap technique for surface treatment of polycarbonate. The discharge system is working in open air at atmospheric pressure. The treatments are carried out at low discharge powers (1.5 and 2 W) for treatment time (2.5 - 15 min). The treated samples show decrease in the contact angle and increase in the crystallinity, thermal stability and surface roughness. The effect of ozone on the increase in the oxygen containing functional groups is discussed. The treatment process shows effective limitation of the migration of bisphenol A from the surface of polycarbonate due to the cross linking. Zero migration of bisphenole A is recorded as the sample is treated for 7.5 min. The treatment process is found to be very efficient with very low cost.展开更多
A new all optical flip-flop based on a 3-sections nonlinear semiconductor DFB laser structure is proposed and simulated. The operation of the device does not require a holding beam. Electrical current injection into a...A new all optical flip-flop based on a 3-sections nonlinear semiconductor DFB laser structure is proposed and simulated. The operation of the device does not require a holding beam. Electrical current injection into an active layer provides optical gain to the laser mode. The wave-guiding layer consists of a linear grating section centered between 2 detuned nonlinear grating sections. The average refractive index in the nonlinear sections is slightly higher than the refractive index of the middle section. A negative nonlinear refractive index coefficient exists along the nonlinear sections. In the “OFF” state, the DFB structure does not provide enough optical feedback to lase due to the detuned sections. At high light intensity in structure, “ON” state, detuning decreases and the DFB structure allows for a laser mode that sustains the decrease in detuning to exist. The nonlinearity is provided by direct photon absorption at the Urbach tail. Numerical simulations using GPGPU computing show nanoseconds transition times between “OFF” and “ON” states.展开更多
A new all-optical flip-flop based on a nonlinear Distributed feedback (DFB) structure is proposed. The device does not require a holding beam. A nonlinear part of the grating is detuned from the remaining part of the ...A new all-optical flip-flop based on a nonlinear Distributed feedback (DFB) structure is proposed. The device does not require a holding beam. A nonlinear part of the grating is detuned from the remaining part of the grating and has negative nonlinear coefficient. Optical gain is provided by an injected electrical current into an active layer. In the OFF state, due to the detuned section, no laser light is generated in the device. An injected optical pulse reduces the detuning of the nonlinear section, and the optical feedback provided by the DFB structure generates a laser light in the structure that sustains the change in the detuned section. The device is switched “OFF” by detuning another section of the grating by a Reset pulse. The Reset pulse reduces the refractive index of that section by the generation of electron-hole pairs. The Reset pulse wavelength is adjusted such that the optical gain provided by the active layer at that wavelength is zero. The Reset pulse is prevented from reaching the nonlinear detuned section by introducing an optical absorber in the laser cavity to attenuate the pulse. The device is simulated in time domain using General Purpose Graphics Processing Unit (GPGPU) computing. Set-Reset operations are in nanosecond time scale.展开更多
A new design for an all optical flip flop is introduced. It is based on a nonlinear Distributed Bragg Reflector (DBR) semiconductor laser structure. The device does not require a holding beam. An optical gain medium c...A new design for an all optical flip flop is introduced. It is based on a nonlinear Distributed Bragg Reflector (DBR) semiconductor laser structure. The device does not require a holding beam. An optical gain medium confined between 2 Bragg reflectors forms the device. One of the Bragg reflectors is detuned from the other by making its average refractive index slightly higher, and it has a negative nonlinear coefficient that is due to direct absorption at Urbach tail. At low light intensity in the structure, the detuned Bragg reflector does not provide optical feedback to start a laser mode. An optical pulse injected to the structure reduces the detuning of the nonlinear Bragg reflector and a laser mode builds up. The device is reset by detuning the second Bragg reflector optically by an optical pulse that generates electron-hole pairs by direct absorption. A mathematical model of the device is introduced. The model is solved numerically in time domain using a general purpose graphics processing unit (GPGPU) to increase accuracy and to reduce the computation time. The switching dynamics of the device are in nanosecond time scale. The device could be used for all optical data packet switching/routing.展开更多
Highly active mesoporous TiO_2 of about 6 nm crystal size and 280.7 m^2/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized ...Highly active mesoporous TiO_2 of about 6 nm crystal size and 280.7 m^2/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized by means of XRD(X-ray diffraction), SEM(scanning electron microscopy), TEM(transmission electron microscopy), FT-IR(Fourier transform infrared spectroscopy), TGA(thermogravimetric analysis), DSC(differential scanning calorimetry) and BET(Brunauer–Emmett–Teller) surface area. The degradation of dichlorophenol-indophenol(DCPIP) under ultraviolet(UV) light was studied to evaluate the photocatalytic activity of samples. The effects of different parameters and kinetics were investigated. Accordingly, a complete degradation of DCPIP dye was achieved by applying the optimal operational conditions of 1 g/L of catalyst, 10 mg/L of DCPIP, pH of 3 and the temperature at 25 ± 3°C after 3 min under UV irradiation. Meanwhile, the Langmuir–Hinshelwood kinetic model described the variations in pure photocatalytic branch in consistent with a first order power law model.The results proved that the prepared TiO_2 nanoparticle has a photocatalytic activity significantly better than Degussa P-25.展开更多
Magnetic yolk-shell structured anatase-based microspheres were fabricated through successive and facile sol-gel coating on magnetite particles, followed by annealing treatments. Upon loading with gold nanoparticles, t...Magnetic yolk-shell structured anatase-based microspheres were fabricated through successive and facile sol-gel coating on magnetite particles, followed by annealing treatments. Upon loading with gold nanoparticles, the obtained functional magnetic microspheres as heterogeneous catalysts showed superior performance in catalyzing the epoxidation of styrene with extraordinary high conversion (89.5%) and selectivity (90.8%) towards styrene oxide. It is believed that the construction process of these fascinating materials features many implications for creating other functional nanocomposites.展开更多
Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparati...Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparation temperature and calcinations' temperature are optimized.Crystallite size, specific surface area, tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction(XRD), thermo gravimetric analysis(TGA), diferential scanning calorimetry(DSC), BET surface area, scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9, preparation temperature of 80℃ and calcinations' temperature of 400℃. The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g, high tetragonal phase percentage of 81% and high catalytic activity(60%) for synthesis of butyl acetate ester.展开更多
Recent studies have suggested that the anti-tumour effect of the programmed cell death protein 1 monoclonal antibody(aPD-1)depends on the expression of interleukin-12(IL-12)by dendritic cells(DCs).Since DCs are abunda...Recent studies have suggested that the anti-tumour effect of the programmed cell death protein 1 monoclonal antibody(aPD-1)depends on the expression of interleukin-12(IL-12)by dendritic cells(DCs).Since DCs are abundant in skin tissues,transdermal delivery of IL-12 targeting DCs may significantly improve the anti-tumour effect of aPD-1.In this study,a novel mannosylated chitosan(MC)-modified ethosome(Eth-MC)was obtained through electrostatic adsorption.The Eth-MC loaded with plasmid containing the IL-12 gene(pIL-12@Eth-MC)stimulated DCs to express mature-related molecular markers such as CD86,CD80,and major histocompatibility complex-II in a targeted manner.The pIL-12@Eth-MC was then mixed with polyvinyl pyrrolidone solution to make microspheres using the electrospray technique,and sprayed onto the surface of electrospun silk fibroin-polyvinyl alcohol nanofibres to obtain a PVP-pIL-12@Eth-MC/silk fibroin-polyvinyl alcohol composite nanofibrous patch(termed a transcutaneous immunization(TCI)patch).The TCI patch showed a good performance on transdermal drug release.Animal experiments on melanoma-bearing mice showed that topical application of the TCI patches promoted the expression of IL-12 and inhibited the growth of tumour.Furthermore,combined application of the TCI patch and aPD-1 showed a stronger anti-tumour effect than aPD-1 monotherapy.The combination therapy significantly promoted the expression of IL-12,interferon-γand tumour necrosis factor-α,the infiltration of CD4+and CD8+T cells into tumour tissues,and thus promoted the apoptosis of tumour cells.The present study provides a convenient and non-invasive strategy for improving the efficacy of immune checkpoint inhibitor therapy.This study was approved by the Institutional Animal Care and Use Committee at Donghua University(approval No.DHUEC-NSFC-2020-11)on March 31,2020.展开更多
文摘In this study,green zinc oxide(ZnO)/polypyrrole(Ppy)/cellulose acetate(CA)film has been synthesized via solvent casting.This film was used as supporting material for glucose oxidase(GOx)to sensitize a glucose biosensor.ZnO nanoparticles have been prepared via the green route using olive leaves extract as a reductant.ZnO/Ppy nanocomposite has been synthesized by a simple in-situ chemical oxidative polymerization of pyrrole(Py)monomer using ferric chloride(FeCl3)as an oxidizing agent.The produced materials and the composite films were characterized using X-ray diffraction analysis(XRD),scanning electron microscope(SEM),Fourier transform infrared(FTIR)and thermogravimetric analysis(TGA).Glucose oxidase was successfully immobilized on the surface of the prepared film and then ZnO/Ppy/CA/GOx composite was sputtered with platinum electrode for the current determination at different initial concentrations of glucose.Current measurements proved the suitability and the high sensitivity of the constructed biosensor for the detection of glucose levels in different samples.The performance of the prepared biosensor has been assessed by measuring and comparing glucose concentrations up to 800 ppm.The results affirmed the reliability of the developed biosensor towards real samples which suggests the wide-scale application of the proposed biosensor.
文摘Essential oils (EOs) are the volatile lipophilic components extracted from plants. Many EOs have demonstrated strong antimicrobial properties when tested in in vitro experiments. The commercial applications of these EOs require a suitable formulation constituted by biodegradable compounds that protect them from degradation and evaporation at the same time that allows for a sustained release. The objective of this study was therefore to reduce the rate of evaporation of the oil via microencapsulation. Alginate microspheres (AMSs) were prepared using emulsion extrusion method. The AMSs were hardened with a cross-linking agent, calcium chloride. The effects of the three variables: alginate concentration (0.5% - 8%), the amount of cross-linking agent (0.125% - 2%) and time of cross-linking (5 - 30 min.) on loading capacity and encapsulation efficiency (EE, %) were studied. The effect of the amount of cross-linker was significant on loading capacity (%) and EE (%). The AMSs under the optimized conditions provided loading capacity of 22% - 24% and EE of 90% - 94% based on type of EO. The antifungal activity of vapors of microencapsulated and non-microencapsulated oils were evaluated against two of pathogenic fungi species for stored grains: Aspergillus niger and Fusarium verticillioides. The optimized MSs were observed to have a sustained in vitro release profile (50% of the antifungal activity was maintained at the 8th day of the study). In conclusion, encapsulation in Ca-alginate microspheres may effectively reduce the evaporation rate of essential oils, thus?increase the potential antifungal activity.
基金The authors extend their appreciation to the Deanship of Scientific Research at the King Khalid University for funding this work through the General Research Project under grant number-R.G.P.1/26/38.
文摘Water contaminated with pathogenic microbes is considered as one of the most common routes for transmitting diseases in human beings.Different methods have been applied for the decontamination of microbes in contaminated water.In the current study,an easy to do hydrothermal method has been used for the preparation of TiO_(2)-Ag nanoparticles.The obtained material was characterised using a scanning electron microscope(SEM)and fourier transform infra-red spectroscopy(FTIR).The morphological appearance of the obtained nanoparticles was in the shape of a sphere with a size range of 60-90 nm.The antimicrobial activity of the prepared nanoparticles was tested against several pathogenic bacteria and fungi.The obtained results proved that the nanoparticles succeeded to affect all the tested microbes in the following order:Bacillus cereus ATCC6633>Pseudomonas aeruginosa ATCC9027=Klebsiella pneumoniae ATCC13883>Vibrio cholera ATCC700=Candida albicans ATCC 700=Escherichia coli NCTC10418>Staphylococcus aureus ATCC6538.The minimum inhibitory concentration(MIC)of the prepared nanoparticles varied among the tested microbes at range of 12 mg/ml and 25 mg/ml.These results encourage the application of prepared TiO_(2)-Ag nanoparticles for treatment of microbe-contaminated waters.
基金Shanghai Science and Technology Committee Project,China(No.18490740400)Open Foundation of Key Laboratory of Science&Technology of Eco-Textile,China(No.Eco-KF-201612)+1 种基金Opening Project of Zhejiang Provincial Preponderant and Characteristic Subject of Key University,Zhejiang Chinese Medical University,China(No.ZYAOX2018035)Project of Health and Family Planning Commission of Zhejiang Province,China(No.2018KY831)
文摘A novel composite carrier of folic acid(FA)-polyethyleneimine(PEI)-ethosome(Eth)(FA-PEI-Eth)was developed for the treatment of cancers through loading and targeting delivery of multidrug(including gene and other drugs)into cancer cells.Physical and chemical property tests were done to prove the grafting of the composite.Gel retardation test was done to determine the optimal ratio of DNA@PEI complex,and cytocompatibility tests and tumor cell uptake tests were done to evaluate the efficiency of the composite.The results demonstrated that the FA-PEI-Eth could effectively deliver a gene and other drugs into tumor cells simultaneously,and suggested that this composite would be a promising carrier in tumor-targeted therapy applications.
基金the General Research Project under grant number-R.G.P.1/26/38.
文摘Current investigation has shown that human exposure to aflatoxins is not limited to the administration of contaminated cereals,but water is another possible source.This study was aimed to design easily applicable method to eliminate aflatoxin B2(AFB2)from contaminated drinking water.Electrospinning has been used for preparation of probiotic-coated polyvinyl alcohol(PVA)and cellulose acetate(CA)nanofibers.Both of these hybrid nanofibers were studied by scanning electron microscopy(SEM)and Fourier-transformed infrared spectroscopy(FT-IR).SEM showed the proper coating of probiotic strains(Kluyveromyces lactis CBS 2359 and Saccharomyces cerevisiae ATCC 9763)on both nanofiber types.Different areas(1-5 cm^(2))of the probiotic-nanofiber hybrid were used to enhance the removal of 20 ng/ml of aflatoxin B2(AFB2)from prepared AFB2-contaminated water over time.Results revealed that a 5 cm^(2) area of probiotic-coated PVA nanofibers can eliminate 97.5% of AFB2 as compared to 87.5%,90.5%,93.5%,and 95.5%,for 1 cm2,2 cm^(2),3 cm^(2),and 4 cm^(2),respectively,while probiotic-coated CA nanofibers were slightly less effective.Nevertheless,the cytotoxicity of probiotics-CA treated water on cultured human fibroblasts was almost 10 times lower than the cytotoxicity recorded in probiotics-PVA treated water.Therefore,results of the current research suggest that probiotics-polymer nanofiber membranes can be used as an extra stage in the water purification system for the treatment of AFB2-contaminated water.
基金funding this work through General Research Project under grant number(R.G.P.1/26/38).
文摘Many recent studies are concerned with low cost,easy to handle and alternative renewable energy as a feasible solution for the upcoming crisis of energy shortage.Microalgae are unicellular entities the can only depend on CO_(2),water and solar power to cover their nutritional needs.The current study is concerned with using algal cells in a polymeric hydrogel,as a cheap source of energy for electricity generation.Chlorella vulgaris has been proved to be a promising algal species for electricity generation,as compared with Micractinium reisseri.PVA hydrogel has been used for the immobilization of both algal species in order to protect them from the adverse surrounding conditions in addition to its ability to slowly release the required water molecules according to needs.Under these conditions,C.vulgaris showed the ability to generate 60 mV compared with 15 mV generated by M.reisseri.Scanning electron micrographs showed nano-threads that bind the C.vulgaris cells to each other,indicating the ability of algae to create nanowires that facilitate the electron transfer among algal cells and from cells to the nearest electrode.However,we would expect an increase in the produced potential with simultaneous amendment of environmentally polluted water,such as sewage or waste water.Both of FTIR and raman spectroscopy proved the presence of the characteristic groups of PVA hydrogel and proved the proper integration of the algal cells inside the hydrogel cavities.
文摘Magnetic alumina nano composite (MANC) was prepared for combination of the adsorption features of nano activated alumina with the magnetic properties of iron oxides to produce a nano magnetic adsorbent, which can be separated from the medium by a simple magnetic process after adsorption. MANC was characterized using XRD, SEM, TEM, EDX and surface area (BET). Quantum design SQUID magnetometer was used to study the magnetic measurement. The present study was conducted to evaluate the feasibility of MANC for the removal of cadmium ions from aqueous solutions through batch adsorption technique. The effects of pH, adsorbent dose, temperature, contact time and initial Cd2+ concentration on cadmium ions adsorption were studied. Equilibrium data were fitted to Langmuir, Freundlich and Temkin isotherms. The equilibrium data were best represented by the Langmuir isotherm. The kinetic data were fitted to pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models, and it was found to follow closely the pseudo-second-order model. Thermodynamic parameters were calculated for the Cd2+ ion-MANC system and the positive value of ΔH° showed that the adsorption was endothermic in nature. Furthermore, a single-stage batch adsorber was designed for the removal of Cd2+ ions by MANC based on the equilibrium data obtained.
文摘A direct synthesis method is introduced to prepare nano-porous silicon-nickel nanocomposite (nPS/Ni) powder for thermal isolation applications. In this paper, we study the thermal stability of nanocomposites consisting of nanoparticles metal incorporated into the pores of a porous silicon by a very simple method. The nickel element is chemically deposited whereas the nanoparticles are precipitated on the pore surfaces. The (nPS) and (nPS/Ni) nano-materials are thermally measured under nitrogen at temperatures of 40℃ - 1000℃, noticeable, demonstrating better thermal stability of (nPS/Ni) until 900℃ than in the case of (nPS) at 600℃. Then, the improving of the thermal stability of the nPS powder is facilitated using it in many applications of the thermal insulation process.
基金support and funding of King Khalid University through Research Center for Advanced Materials Science(RCAMS)under grant no:RCAMS/KKU/008/21the support provided by King Abdullah City for Atomic and Renewable Energy(K.A.CARE)under K.A.CARE-King Abdulaziz University Collaboration Program。
文摘A translucent wooden substrate with long-lasting phosphorescence,high photostability and durability,tough surface,ultraviolet protection,high optical transmittance,and superhydrophobicity was developed.This long-lasting phosphorescent wooden substrate is able to continue emitting light for extended time periods.Lignin-modified wood(LMW)was immobilized with a solution of epoxy resin(ER)and rare-earth doped aluminate(REDA)phosphor nanoparticles(NPs).For an improved dispersion of pigment,REDA was synthesized in a nanoscale particle size,and characterized by transmission electron microscopy(TEM)to indicate a particle size of 8-14 nm.The crystal structure of REDA nanoparticles was also proved by X-ray diffraction(XRD).For an improved production of long-persistent phosphorescent colo rless woods,REDA must be well-dispersed in MAA without aggregation.Absorption and emissio n,as well as decay and lifetime spectra were explored.The morphologies of the wooden substrates with different ratios of REDA were investigated by scanning electron microscopy(SEM),X-ray fluorescence(XRF)analysis,Fourier transform infrared spectra(FT-IR),elemental mapping,and energy-dispersion Xray(EDXA).The phosphorescent woods show changes in color from colorless to green under ultraviolet(UV)irradiation,and to yellowish-green in the dark,as proved by the colorimetric parameters of the CIE Lab system.The afterglow wood samples display an absorbance band at 365 nm and two phosphorescent bands at 431 and 520 nm.Improved UV shielding,photostability,and hydrophobicity were explored.With increasing REDA ratio,both static contact and slide angles are found to improve in the ranges of147.6°-163.6°and 9°-14°,respectively.The long-lasting photoluminescence is optimized at a REDA ratio of 8%.The present strategy shows a large-scale production approach of multiple functional woods for many potential applications,such as smart glow in the dark windows and safety signs.
文摘The purpose of the present research is the different morphologies production of crystalline and amorphous-silica powder. It’s a basic material for many pharmaceutical and environmental applications as well. And, it’s produced using the combination of the alkali chemical etching process and the ultra-sonication technique. The critical preparation conditions are KOH concentration (weight %) and the sonication time (hour). The paper presents the chemical mechanism of the silica particle formation as well as the different morphology. The results show the formation of crystalline and amorphous-porous-silica particles in the micrometer range with the porous order network that has pore sizes range in micrometer too. This synthetic uses commercial silicon, which could be useful for large-scale production. Also, the nano-sphere and nano-cubic shapes of silica powder are formed starting by commercial silicon powder.
文摘This paper reports the feasibility of synthesis and characterization of nano-porous silicon (NPS) powder and (Nickel/nano-porous silicon, Ni/NPS) nano-composite prepared using dual techniques (alkaline chemical etching process and ultra-sonication technique). The structural and the optical properties of the fabricated structures are inspected using X-ray Diffraction, Fourier Transform Infrared Spectrophotometer, Raman Spec-troscopy, and Fluorescence Spectrophotometer Photoluminescence. All the results have agreed that NPS is one of the most suitable materials used as active material in the LED fabrication;by changing the main factors in the preparation process, so the different physical and chemical properties are obtained. NPS produces two emission regions that correspond to orange-red and dark red;on the other hand, (Ni/NPS) produce the yellow emission. So, the photoluminescence emission is controllable by adjusting the preparation conditions. The optical data recorded here are useful for the production of the nanoscale optical devices.
文摘The fabrication of nano porous silicon, nPSi, using alkali etching process has been studied and carried out. The surface chemistry of anisotropic etching of n-type Si-wafer is reviewed and the anisotropic chemical etching of silicon in alkaline solution using wetting agents is discussed. Transformation of crystallographic plane of n-Si (211) to nPSi (100) has occurred on using n-propanol as wetting agent. The rate of pore formation was 0.02478 - 0.02827 μm/min, which was heavily dependent upon the concentration of the etchant containing wetting agents, allowing patterned porous silicon formation through selective doping of the substrate. A particle size of 15 nm for porous nano-silicon was calculated from the XRD data. Porosity of PS layers is about 10%. Pore diameter and porous layer thickness are 0.0614 nm and 16 μm, respectively. The energy gap of the produced porous silicon is 3.3 eV. Furthermore, the combination of PS with Congo Red, which are nanostructured due to their deposition within the porous matrix is discussed. Such nano compounds offer broad avenue of new and interesting properties depending on the involved materials as well as on their morphology. Chemical route was utilized as the host material to achieve pores filling. They were impregnated with Congo Red, which gave good results for the porous silicon as a promising pH sensor.
文摘Dielectric barrier discharge is used as a cheap technique for surface treatment of polycarbonate. The discharge system is working in open air at atmospheric pressure. The treatments are carried out at low discharge powers (1.5 and 2 W) for treatment time (2.5 - 15 min). The treated samples show decrease in the contact angle and increase in the crystallinity, thermal stability and surface roughness. The effect of ozone on the increase in the oxygen containing functional groups is discussed. The treatment process shows effective limitation of the migration of bisphenol A from the surface of polycarbonate due to the cross linking. Zero migration of bisphenole A is recorded as the sample is treated for 7.5 min. The treatment process is found to be very efficient with very low cost.
文摘A new all optical flip-flop based on a 3-sections nonlinear semiconductor DFB laser structure is proposed and simulated. The operation of the device does not require a holding beam. Electrical current injection into an active layer provides optical gain to the laser mode. The wave-guiding layer consists of a linear grating section centered between 2 detuned nonlinear grating sections. The average refractive index in the nonlinear sections is slightly higher than the refractive index of the middle section. A negative nonlinear refractive index coefficient exists along the nonlinear sections. In the “OFF” state, the DFB structure does not provide enough optical feedback to lase due to the detuned sections. At high light intensity in structure, “ON” state, detuning decreases and the DFB structure allows for a laser mode that sustains the decrease in detuning to exist. The nonlinearity is provided by direct photon absorption at the Urbach tail. Numerical simulations using GPGPU computing show nanoseconds transition times between “OFF” and “ON” states.
文摘A new all-optical flip-flop based on a nonlinear Distributed feedback (DFB) structure is proposed. The device does not require a holding beam. A nonlinear part of the grating is detuned from the remaining part of the grating and has negative nonlinear coefficient. Optical gain is provided by an injected electrical current into an active layer. In the OFF state, due to the detuned section, no laser light is generated in the device. An injected optical pulse reduces the detuning of the nonlinear section, and the optical feedback provided by the DFB structure generates a laser light in the structure that sustains the change in the detuned section. The device is switched “OFF” by detuning another section of the grating by a Reset pulse. The Reset pulse reduces the refractive index of that section by the generation of electron-hole pairs. The Reset pulse wavelength is adjusted such that the optical gain provided by the active layer at that wavelength is zero. The Reset pulse is prevented from reaching the nonlinear detuned section by introducing an optical absorber in the laser cavity to attenuate the pulse. The device is simulated in time domain using General Purpose Graphics Processing Unit (GPGPU) computing. Set-Reset operations are in nanosecond time scale.
文摘A new design for an all optical flip flop is introduced. It is based on a nonlinear Distributed Bragg Reflector (DBR) semiconductor laser structure. The device does not require a holding beam. An optical gain medium confined between 2 Bragg reflectors forms the device. One of the Bragg reflectors is detuned from the other by making its average refractive index slightly higher, and it has a negative nonlinear coefficient that is due to direct absorption at Urbach tail. At low light intensity in the structure, the detuned Bragg reflector does not provide optical feedback to start a laser mode. An optical pulse injected to the structure reduces the detuning of the nonlinear Bragg reflector and a laser mode builds up. The device is reset by detuning the second Bragg reflector optically by an optical pulse that generates electron-hole pairs by direct absorption. A mathematical model of the device is introduced. The model is solved numerically in time domain using a general purpose graphics processing unit (GPGPU) to increase accuracy and to reduce the computation time. The switching dynamics of the device are in nanosecond time scale. The device could be used for all optical data packet switching/routing.
基金funded by the Science and Technology Development Fund (STDF), Ministry of Scientific Research (No. 1414, "Quantum Dots Nanomaterials Dye Sensitized Solar Cells")
文摘Highly active mesoporous TiO_2 of about 6 nm crystal size and 280.7 m^2/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized by means of XRD(X-ray diffraction), SEM(scanning electron microscopy), TEM(transmission electron microscopy), FT-IR(Fourier transform infrared spectroscopy), TGA(thermogravimetric analysis), DSC(differential scanning calorimetry) and BET(Brunauer–Emmett–Teller) surface area. The degradation of dichlorophenol-indophenol(DCPIP) under ultraviolet(UV) light was studied to evaluate the photocatalytic activity of samples. The effects of different parameters and kinetics were investigated. Accordingly, a complete degradation of DCPIP dye was achieved by applying the optimal operational conditions of 1 g/L of catalyst, 10 mg/L of DCPIP, pH of 3 and the temperature at 25 ± 3°C after 3 min under UV irradiation. Meanwhile, the Langmuir–Hinshelwood kinetic model described the variations in pure photocatalytic branch in consistent with a first order power law model.The results proved that the prepared TiO_2 nanoparticle has a photocatalytic activity significantly better than Degussa P-25.
文摘Magnetic yolk-shell structured anatase-based microspheres were fabricated through successive and facile sol-gel coating on magnetite particles, followed by annealing treatments. Upon loading with gold nanoparticles, the obtained functional magnetic microspheres as heterogeneous catalysts showed superior performance in catalyzing the epoxidation of styrene with extraordinary high conversion (89.5%) and selectivity (90.8%) towards styrene oxide. It is believed that the construction process of these fascinating materials features many implications for creating other functional nanocomposites.
文摘Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparation temperature and calcinations' temperature are optimized.Crystallite size, specific surface area, tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction(XRD), thermo gravimetric analysis(TGA), diferential scanning calorimetry(DSC), BET surface area, scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9, preparation temperature of 80℃ and calcinations' temperature of 400℃. The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g, high tetragonal phase percentage of 81% and high catalytic activity(60%) for synthesis of butyl acetate ester.
基金supported by the Science&Technology Commission of Shanghai Municipality of China,Nos.18490740400,20DZ2254900the National Key Research&Development Program of China,No.2018YFC1706200.
文摘Recent studies have suggested that the anti-tumour effect of the programmed cell death protein 1 monoclonal antibody(aPD-1)depends on the expression of interleukin-12(IL-12)by dendritic cells(DCs).Since DCs are abundant in skin tissues,transdermal delivery of IL-12 targeting DCs may significantly improve the anti-tumour effect of aPD-1.In this study,a novel mannosylated chitosan(MC)-modified ethosome(Eth-MC)was obtained through electrostatic adsorption.The Eth-MC loaded with plasmid containing the IL-12 gene(pIL-12@Eth-MC)stimulated DCs to express mature-related molecular markers such as CD86,CD80,and major histocompatibility complex-II in a targeted manner.The pIL-12@Eth-MC was then mixed with polyvinyl pyrrolidone solution to make microspheres using the electrospray technique,and sprayed onto the surface of electrospun silk fibroin-polyvinyl alcohol nanofibres to obtain a PVP-pIL-12@Eth-MC/silk fibroin-polyvinyl alcohol composite nanofibrous patch(termed a transcutaneous immunization(TCI)patch).The TCI patch showed a good performance on transdermal drug release.Animal experiments on melanoma-bearing mice showed that topical application of the TCI patches promoted the expression of IL-12 and inhibited the growth of tumour.Furthermore,combined application of the TCI patch and aPD-1 showed a stronger anti-tumour effect than aPD-1 monotherapy.The combination therapy significantly promoted the expression of IL-12,interferon-γand tumour necrosis factor-α,the infiltration of CD4+and CD8+T cells into tumour tissues,and thus promoted the apoptosis of tumour cells.The present study provides a convenient and non-invasive strategy for improving the efficacy of immune checkpoint inhibitor therapy.This study was approved by the Institutional Animal Care and Use Committee at Donghua University(approval No.DHUEC-NSFC-2020-11)on March 31,2020.