Effects of carbon nanotubes （CNT） and alumina （γ-Al2O3） supports on the catalytic activities of hydrodesulfurization （HDS） process over Co- Mo catalyst have been studied. XRD results indicated that the main act...Effects of carbon nanotubes （CNT） and alumina （γ-Al2O3） supports on the catalytic activities of hydrodesulfurization （HDS） process over Co- Mo catalyst have been studied. XRD results indicated that the main active phases in CNT and γ-Al2O3 supported Co-Mo catalysts are MoO2 and MOO3, respectively. The TPR results reveal that the reduction peak temperatures of the active species on CNT supported Co-Mo catalyst is lower than those on alumina supported Co-Mo catalyst, indicating that the CNT supports favor the reduction of active species. Catalytic evaluation results displayed that the sulfur content in the reaction products on the CNT supported Co-Mo catalyst is lower than that on the alumina supported Co-Mo catalyst if the HDS reaction was carried out at a temperature above 583 K.展开更多
Different mesoporous activated carbons were prepared by both chemical and physical activation processes and were examined for methane uptake in the presence of water.Methane isotherms were obtained at wet condition by...Different mesoporous activated carbons were prepared by both chemical and physical activation processes and were examined for methane uptake in the presence of water.Methane isotherms were obtained at wet condition by wetting samples with water at mass ratio of water/carbon(R) close to 1.0.To compare,the amount of methane storage were also measured at dry situation.The maximum amount of methane stored was attained as 237 V/V at R=1.0 by hydrate formation at the methane critical pressure.In the next step,mass ratios of water/carbon were changed to investigate various amount of water for methane storage enhancement.Two other values of mass ratio of water/carbon(R=0.8 and 1.4) were selected and methane isotherms were obtained at the same conditions.Maximum values of 210 and 248 V/V were reached for methane storage,respectively.It was also observed that,in the pressure range lower than hydrate pressure,by increasing water ratio the hydrate formation pressure was decreased and methane uptake was much less than that of dry condition due to pore filling by water.展开更多
Photonic crystal fibers （PCFs） with a stepped raised-core profile and one layer equally spaced holes in the cladding are analyzed. Using effective index method and considering a raised step refractive index differen...Photonic crystal fibers （PCFs） with a stepped raised-core profile and one layer equally spaced holes in the cladding are analyzed. Using effective index method and considering a raised step refractive index difference between the index of the core and the effective index of the cladding, we improve the characteristic parameters such as numerical aperture and V-parameter, and reduce its bending loss to about one tenth of a conventional PCF. Implementing such a structure in PCFs may be one step forward to achieve low loss PCFs for communication applications.展开更多
In this study, a reliable algorithm to develop approximate solutions for the problem of fluid flow over a stretching or shrinking sheet is proposed. It is depicted that the differential transform method (DTM) solution...In this study, a reliable algorithm to develop approximate solutions for the problem of fluid flow over a stretching or shrinking sheet is proposed. It is depicted that the differential transform method (DTM) solutions are only valid for small values of the independent variable. The DTM solutions diverge for some differential equations that extremely have nonlinear behaviors or have boundary-conditions at infinity. For this reason the governing boundary-layer equations are solved by the Multi-step Differential Transform Method (MDTM). The main advantage of this method is that it can be applied directly to nonlinear differential equations without requiring linearization, discretization, or perturbation. It is a semi analytical-numerical technique that formulizes Taylor series in a very different manner. By applying the MDTM the interval of convergence for the series solution is increased. The MDTM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions for systems of differential equations. It is predicted that the MDTM can be applied to a wide range of engineering applications.展开更多
Transcranial direct current stimulation(tDCS)has been reportedly beneficial for different neurodegenerative disorders.tDCS has been reported as a potential adjunctive or alternative treatment for auditory verbal hallu...Transcranial direct current stimulation(tDCS)has been reportedly beneficial for different neurodegenerative disorders.tDCS has been reported as a potential adjunctive or alternative treatment for auditory verbal hallucination(AVH).This study aims to review the effects of tDCS on AVH in patients with schizophrenia through combining the evidence from randomized clinical trials(RCTs).The databases of PsycINFO(2000–2019),PubMed(2000–2019),EMBASE(2000–2019),CINAHL(2000–2019),Web of Science(2000–2019),and Scopus(2000–2019)were systematically searched.The clinical trials with RCT design were selected for final analysis.A total of nine RCTs were eligible and included in the review.Nine RCTs were included in the final analysis.Among them,six RCTs reported a significant reduction of AVH after repeated sessions of tDCS,whereas three RCTs did not show any advantage of active tDCS over sham tDCS.The current studies showed an overall decrease of approximately 28%of AVH after active tDCS and 10%after sham tDCS.The tDCS protocols targeting the sensorimotor frontal-parietal network showed greater treatment effects compared with the protocols targeting other regions.In this regard,cathodal tDCS over the left temporoparietal area showed inhibitory effects on AVHs.The most effective tDCS protocol on AVHs was twice-daily sessions(2 mA,20-minute duration)over 5 consecutive days(10 sessions)with the anode over the left dorsolateral prefrontal cortex and the cathode over the left temporal area.Some patient-specific and diseasespecific factors such as young age,nonsmoking status,and higher frequencies of AVHs seemed to be the predictors of treatment response.Taken together,the results of tDCS as an alternative treatment option for AVH show controversy among current literatures,since not all studies were positive.However,the studies targeting the same site of the brain showed that the tDCS could be a promising treatment option to reduce AVH.Further RCTs,with larger sample sizes,should be conducted to reach a conclusion on the 展开更多
In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were charac...In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.展开更多
AIM:To investigate the impact of niosome nanoparticles carrying umbelliprenin(UMB),an anti-angiogenic and anti-inflammatory plant compound,on the expression of vascular endothelial growth factor(VEGF-A)and connective ...AIM:To investigate the impact of niosome nanoparticles carrying umbelliprenin(UMB),an anti-angiogenic and anti-inflammatory plant compound,on the expression of vascular endothelial growth factor(VEGF-A)and connective tissue growth factor(CTGF)genes in a human retinal pigment epithelium(RPE)-like retina-derived cell line.METHODS:UMB-containing niosomes were created,optimized,and characterized.RPE-like cells were treated with free UMB and UMB-containing niosomes.The IC_(50)values of the treatments were determined using an MTT assay.Gene expression of VEGF-A and CTGF was evaluated using real-time polymerase chain reaction after RNA extraction and cDNA synthesis.Niosomes’characteristics,including drug entrapment efficiency,size,dispersion index,and zeta potential were assessed.Free UMB had an IC_(50)of 96.2μg/mL,while UMB-containing niosomes had an IC_(50)of 25μg/mL.RESULTS:Treatment with UMB-containing niosomes and free UMB resulted in a significant reduction in VEGF-A expression compared to control cells(P=0.001).Additionally,UMB-containing niosomes demonstrated a significant reduction in CTGF expression compared to control cells(P=0.05).However,there was no significant reduction in the expression of both genes in cells treated with free UMB.CONCLUSION:Both free UMB and niosome-encapsulated UMB inhibits VEGF-A and CTGF genes expression.However,the latter demonstrates significantly greater efficacy,potentially due to the lower UMB dosage and gradual delivery.These findings have implications for anti-angiogenesis therapeutic approaches targeting age-related macular degeneration.展开更多
Despite modern medicine’s advancements,age-related neurological diseases like Alzheimer’s disease and Parkinson’s disease remain challenging due to high costs,side effects,and limited accessibility.Ayurveda,a tradi...Despite modern medicine’s advancements,age-related neurological diseases like Alzheimer’s disease and Parkinson’s disease remain challenging due to high costs,side effects,and limited accessibility.Ayurveda,a traditional Indian medicine system,offers Kadha tea as a potential herbal option.This review explores Kadha’s components(basil(Ocimum basilicum L.),black pepper(Piper nigrum L.),Cinnamon(Cinnamomum verum J.Presl),ginger(Zingiber officinale Roscoe),and raisin(Vitis vinifera L.))and their interaction with various neurological disorders.Studies suggest Kadha exhibits anti-inflammatory,antioxidant,and antiviral properties,potentially impacting Alzheimer’s disease,Parkinson’s disease,neurotoxicity,neuroinflammation,and brain trauma.By focusing on specific disease mechanisms and Kadha’s intergrade effects,this review aims to elucidate its potential role in managing age-related neurological disorders.展开更多
In this paper,the experimental investigation on the performance improvement of conventional stepped solar still is conducted.The steps are covered by the porous material to improve the performance of the conventional ...In this paper,the experimental investigation on the performance improvement of conventional stepped solar still is conducted.The steps are covered by the porous material to improve the performance of the conventional device and increase the evaporation rate.All the parameters,including the temperature on the glass surface,the water temperature inside the evaporation zone,and the amount of water produced in both conventional and modified stepped solar stills are measured and compared.The efficiency of two devices and their exergy efficiency have been calculated.Finally,the economic analysis of both devices has been done to check the economic feasibility of the modified device.The amount of freshwater generated during one day was 2244.4 and 3076.2 mL/m^(2),respectively for the conventional and modified stepped solar stills.As a result,the amount of water produced in one day by modified stepped solar still is 35.5% more than the conventional one.Also,the costs for the conventional and modified stepped solar stills have been calculated as 0.0359 and 0.029$/(L·m^(-2)),respectively.展开更多
Exploitation of sustainable energy sources requires the use of unique conversion and storage systems,such as solar panels,batteries,fuel cells,and electronic equipment.Thermal load management of these energy conversio...Exploitation of sustainable energy sources requires the use of unique conversion and storage systems,such as solar panels,batteries,fuel cells,and electronic equipment.Thermal load management of these energy conversion and storage systems is one of their challenges and concerns.In this article,the thermal management of these systems using thermoelectric modules is reviewed.The results show that by choosing the right option to remove heat from the hot side of the thermoelectric modules,it will be a suitable local cooling,and the thermoelectric modules increase the power and lifespan of the system by reducing the spot temperature.Thermoelectric modules were effective in reducing panel temperature.They increase the time to reach a temperature above 50℃ in batteries by 3 to 4 times.Also,in their integration with fuel cells,they increase the power density of the fuel cell.展开更多
In order to reduce the sulfur compounds in diesel fuel,boron nitride(BN)has been used as a novel metal-free catalyst in the present research.This nanocatalyst was synthesized via template-free approach followed by hea...In order to reduce the sulfur compounds in diesel fuel,boron nitride(BN)has been used as a novel metal-free catalyst in the present research.This nanocatalyst was synthesized via template-free approach followed by heating treatment at 900℃ in nitrogen atmosphere that the characteristics of the sample were identified by the X-ray diffraction,Fourier-transform infrared spectroscopy,Raman spectroscopy,field emission scanning electron microscopy,transmission electron microscopy,atomic force microscopy,and N2 adsorption-desorption isotherms.The results of structural and morphological analysis represented that BN has been successfully synthesized.The efficacy of the main operating parameters on the process was studied by using response surface methodology based on the Box-Behnken design method.The prepared catalyst showed high efficiency in oxidative desulfurization of diesel fuel with initial sulfur content of 8040 mg·kg^(-1)S.From statistical analysis,a significant quadratic model was obtained to predict the sulfur removal as a function of efficient parameters.The maximum efficiency of 72.4%was achieved under optimized conditions at oxidant/sulfur molar ratio of 10.2,temperature of 71℃,reaction time of 113 min,and catalyst dosage of 0.36 g.Also,the reusability of the BN was studied,and the result showed little reduction in activity of the catalyst after 10 times regeneration.Moreover,a plausible mechanism was proposed for oxidation of sulfur compounds on the surface of the catalyst.The present study shows that BN materials can be selected as promising metal-free catalysts for desulfurization process.展开更多
In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes（SWNTs）have been investigated.In both reactors,single-walled carbon nanotubes were grown by catal...In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes（SWNTs）have been investigated.In both reactors,single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition（CCVD）of methane over Co-Mo/MgO nanocatalyst under two different operating conditions.The synthesized samples were characterized by TEM,TGA and Raman spectroscopy.It is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed bed.The quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of 0.71.Also,the yield of SWNTs in the fluidized bed was 92 wt%,while it was 78 wt%in the fixed bed.These advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.展开更多
AIM： To compare the effectiveness of triple, standard quadruple and ampicillin-sulbactam-based quadruple therapies for Hpylori eradication in a comparative three-armed randomized clinical trial. METHODS： A total of ...AIM： To compare the effectiveness of triple, standard quadruple and ampicillin-sulbactam-based quadruple therapies for Hpylori eradication in a comparative three-armed randomized clinical trial. METHODS： A total of 360 H pylori-positive patients suffering from dyspepsia and aging 24-79 years with a median age of 42 years were enrolled in the study and randomly allocated into the following three groups： group A （n = 120） received a standard 1-wk triple therapy （20 mg omeprazole b.i.d., 1000 mg amoxicillin b.i.d., 500 mg clarithromycin b.i.d.）, group B （n = 120） received a 10-d standard quadruple therapy （20 mg omeprazole b.i.d., 1000 mg amoxicillin b.i.d., 240 mg colloidal bismuth subcitrate b.i.d., and 500 mg metronidazole b.i.d.）, group C （n = 120） received the new protocol, i.e. 375 mg sultamicillin （225 mg ampicillin plus 150 mg sulbactam） b.i.d. （before breakfast and dinner）, instead of amoxicillin in the standard quadruple therapy for the same duration. Chi-square test with the consideration of P 〈 0.05 as significant was used to compare the eradication rates by intention-to-treat and per-protocol analyses in the three groups.RESULTS： The per-protocol eradication rate was 91.81% （101 patients from a total of 110） in group A, 85.84% （97 patients from a total of 113） in group B, and 92.85% （104 patients from a total of 112） in group C. The intention-to-treat eradication rate was 84.17% in group A, 80.83% in group B, and 86.67% in group C. The new protocol yielded the highest eradication rates by both per-protocol and intention-to-treat analyses followed by the standard triple and quadruple regimens, respectively. However, the differences were not statistically significant between the three groups. CONCLUSION： The results of this study provide further support for the equivalence of triple and quadruple therapies in terms of effectiveness, compliance and sideeffect profile when administered as first-line treatment for H pylori infection. Moreover, the new proto展开更多
AIM: To investigate the cause of acute pancreatitis(AP) by conducting a thorough investigation of drugs and their possible etiological role.METHODS: We investigated the cause of AP in a large retrospective cohort of 6...AIM: To investigate the cause of acute pancreatitis(AP) by conducting a thorough investigation of drugs and their possible etiological role.METHODS: We investigated the cause of AP in a large retrospective cohort of 613 adult patients admitted with AP at the Akershus University Hospital, Norway, from 2000 until 2009, who were evaluated with standard ward investigations. This group was compared with a prospectively evaluated group(n = 57) admitted from January 2010 until September 2010 who investigated more extensively using medical history and radiological assessment.RESULTS: The groups were comparable with regards to gender, age, comorbidity and severity. The most common etiology was bile stones and alcohol, occurring in 60% in both groups. The prospective group was examined more thoroughly with regards to the use of alcohol and medicines. An increased number of radiological investigations during hospital stay and at follow-up were also performed. A more extensive use of radiological evaluation did not increase the detection frequency of bile stones. In the prospective group, more than half of the patients had two or more possible causes of pancreatitis, being mostly a combination of bile stones and drugs. No possible cause was found in only 3.5% of these patients, compared with 29.7% in the retrospective group.CONCLUSION: A detailed medical history and extensive radiological evaluation may determine a possible etiology in almost all cases of AP. Many patients have several possible risk factors, and uncertainty remains in establishing the definitive etiology.展开更多
The main purpose of this study is to survey numerically comparison of two- phase and single phase of heat transfer and flow field of copper-water nanofluid in a wavy channel. The computational fluid dynamics （CFD） p...The main purpose of this study is to survey numerically comparison of two- phase and single phase of heat transfer and flow field of copper-water nanofluid in a wavy channel. The computational fluid dynamics （CFD） prediction is used for heat transfer and flow prediction of the single phase and three different two-phase models （mixture, volume of fluid （VOF）, and Eulerian）. The heat transfer coefficient, temperature, and velocity distributions are investigated. The results show that the differences between the temperature fie].d in the single phase and two-phase models are greater than those in the hydrodynamic tleld. Also, it is found that the heat transfer coefficient predicted by the single phase model is enhanced by increasing the volume fraction of nanoparticles for all Reynolds numbers; while for the two-phase models, when the Reynolds number is low, increasing the volume fraction of nanoparticles will enhance the heat transfer coefficient in the front and the middle of the wavy channel, but gradually decrease along the wavy channel.展开更多
Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating...Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating fouling in the marine environment.Meanwhile,nanocomposite polymer coatings are a novel generation of antifouling coatings with merits of toxin-free chemical composition and ease of large-scale application.Nanomaterials such as nano-metals,nano-metal oxides,metal-organic frameworks,carbon-based nanostructures,MXene,and nanoclays have antibacterial and antifouling properties in the polymer coatings.Besides,these nanomaterials can improve the corrosion resistance,mechanical strength,weathering stability,and thermal resistance of the polymer coatings.Therefore,in this review paper,the antifouling nanocomposite coatings are introduced and antifouling mechanisms are discussed.This review explicitly indicates that the antifouling efficiency of the nanocomposite coatings depends on the properties of the polymer matrix,the inherent properties of the nanomaterials,the weight percent and the dispersion method of the nanomaterials within the coating matrix,and the chemicals used for modifying the surface of the nanomaterials;meanwhile,the hybrids of different nanomaterials and appropriate chemical agents could be used to improve the antifouling behavior of the prepared nanocomposites.Moreover,the theoretical studies are introduced to pave the way of researchers working on theantifouling coatings,and the importance of the theoretical studies and computational modeling along with the experimental research is notified to develop antifouling coatings with high efficiency.展开更多
AIM： To compare the response of standard hepatitis B virus （HBV） vaccination between patients with chronic hepatitis C virus （HCV） infection and healthy individuals. METHODS： This is a prospective case-control s...AIM： To compare the response of standard hepatitis B virus （HBV） vaccination between patients with chronic hepatitis C virus （HCV） infection and healthy individuals. METHODS： This is a prospective case-control study. A total of 38 patients with chronic HCV infection and 40 healthy controls were included. Vaccination was performed by injection of 20μg recombinant HBsAg into the deltoid muscle at mo 0,1 and 6. Anti-HBs concentration was determined 3 mo after the last dose and compared between the two groups. The response pattern was characterized as （1） high-response when the anti-HBs antibody titer was 〉 100 IU/L, （2） low-response when the titer was 10-100 IU/L. and （3） no-response when the titer was 〈 10 IU/L. RESULTS： In the patient group, there were 10/38 （26.3%） non-responders, 8/38 （21.1%） Iow-responders and 20/38 （52.6%） high-responders. The corresponding values in the control group were 2/40 （5.0%）, 7/40 （17.5%） and 31/40 （77.5%）, respectively. The response pattern was statistically different between the two groups. In multivariate analysis, smoking was a significant confounder, while HCV infection lost its significant correlation with lower antibody response. CONCLUSION： Patients with chronic HCV infection tend to respond weakly to HBV vaccination compared to healthy individuals, though this correlation is not independent according to multivariate analysis.展开更多
Herein,nitrogen and sulfur co-doped carbon nanotubes(NS-CNT)adsorbents were synthesized via the chemical vapor deposition technique at 1000°C by employing the camphor,urea and sulfur trioxide pyridine.In this stu...Herein,nitrogen and sulfur co-doped carbon nanotubes(NS-CNT)adsorbents were synthesized via the chemical vapor deposition technique at 1000°C by employing the camphor,urea and sulfur trioxide pyridine.In this study,desulfurization of two types of mercaptans(dibenzothiophene(DBT)and tertiary butyl mercaptan(TBM)as nonlinear and linear forms of mercaptan)was studied.In this regard,a maximum capacity of NS-CNT was obtained as 106.9 and 79.4 mg/g and also the removal efficiencies of 98.6%and 88.3%were achieved after 4 h at 298K and 0.9 g of NS-CNT for DBT and TBM,respectively.Characterization of the NS-CNTs was carried out through exploiting scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and elemental analysis(CHN).The isotherm equilibrium data could be ascribed to the Freundlich nonlinear regression form and the kinetic data was fitted by nonlinear form of the pseudo second order model.The negative values of ΔS^(0),ΔH^(0) and ΔG^(0) specify that the adsorption of both types of mercaptans was a natural exothermic process with a reduced entropy.Maintenance of more than 96%of the adsorption capacity even after nine cycles suggest the NS-CNT as a superior adsorbent for mercaptans removal in the industry.Density functional theory(DFT)calculations were also performed to peruse the effects of S/N co-doping and carbon monovacancy defects in CNTs toward the adsorption of DBT and TBM.展开更多
Scanning electron microscopy shows that the microstructure,in particular the overall grain size,of chemical vapor deposited silicon carbide coatings depends on the deposition temperature.Sofar,the influence of the mic...Scanning electron microscopy shows that the microstructure,in particular the overall grain size,of chemical vapor deposited silicon carbide coatings depends on the deposition temperature.Sofar,the influence of the microstructure on the mechanical properties of such coatings is not well described in literature.To investigate the influence of the deposition temperature on the mechanical properties of the coating,nanoindentation is used in this work.Since the measurement results of nanoindentation can be affected by the substrate material,the contribution of the substrate material is taken into account utilizing a finite element model.The model is then employed to generate information about elastic and plastic properties of the coating by inverse simulation.To evaluate the fracture toughness of the coating,the generated material model is used in a cohesive-zone based formulation of the fracture process during indentation at higher loads.The results of this model allow determining the fracture toughness of silicon carbide coatings deposited at different temperatures.展开更多
文摘Effects of carbon nanotubes （CNT） and alumina （γ-Al2O3） supports on the catalytic activities of hydrodesulfurization （HDS） process over Co- Mo catalyst have been studied. XRD results indicated that the main active phases in CNT and γ-Al2O3 supported Co-Mo catalysts are MoO2 and MOO3, respectively. The TPR results reveal that the reduction peak temperatures of the active species on CNT supported Co-Mo catalyst is lower than those on alumina supported Co-Mo catalyst, indicating that the CNT supports favor the reduction of active species. Catalytic evaluation results displayed that the sulfur content in the reaction products on the CNT supported Co-Mo catalyst is lower than that on the alumina supported Co-Mo catalyst if the HDS reaction was carried out at a temperature above 583 K.
基金Shahid Hashemi Nejad Gas refinery for supporting this project
文摘Different mesoporous activated carbons were prepared by both chemical and physical activation processes and were examined for methane uptake in the presence of water.Methane isotherms were obtained at wet condition by wetting samples with water at mass ratio of water/carbon(R) close to 1.0.To compare,the amount of methane storage were also measured at dry situation.The maximum amount of methane stored was attained as 237 V/V at R=1.0 by hydrate formation at the methane critical pressure.In the next step,mass ratios of water/carbon were changed to investigate various amount of water for methane storage enhancement.Two other values of mass ratio of water/carbon(R=0.8 and 1.4) were selected and methane isotherms were obtained at the same conditions.Maximum values of 210 and 248 V/V were reached for methane storage,respectively.It was also observed that,in the pressure range lower than hydrate pressure,by increasing water ratio the hydrate formation pressure was decreased and methane uptake was much less than that of dry condition due to pore filling by water.
文摘Photonic crystal fibers （PCFs） with a stepped raised-core profile and one layer equally spaced holes in the cladding are analyzed. Using effective index method and considering a raised step refractive index difference between the index of the core and the effective index of the cladding, we improve the characteristic parameters such as numerical aperture and V-parameter, and reduce its bending loss to about one tenth of a conventional PCF. Implementing such a structure in PCFs may be one step forward to achieve low loss PCFs for communication applications.
文摘In this study, a reliable algorithm to develop approximate solutions for the problem of fluid flow over a stretching or shrinking sheet is proposed. It is depicted that the differential transform method (DTM) solutions are only valid for small values of the independent variable. The DTM solutions diverge for some differential equations that extremely have nonlinear behaviors or have boundary-conditions at infinity. For this reason the governing boundary-layer equations are solved by the Multi-step Differential Transform Method (MDTM). The main advantage of this method is that it can be applied directly to nonlinear differential equations without requiring linearization, discretization, or perturbation. It is a semi analytical-numerical technique that formulizes Taylor series in a very different manner. By applying the MDTM the interval of convergence for the series solution is increased. The MDTM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions for systems of differential equations. It is predicted that the MDTM can be applied to a wide range of engineering applications.
文摘Transcranial direct current stimulation(tDCS)has been reportedly beneficial for different neurodegenerative disorders.tDCS has been reported as a potential adjunctive or alternative treatment for auditory verbal hallucination(AVH).This study aims to review the effects of tDCS on AVH in patients with schizophrenia through combining the evidence from randomized clinical trials(RCTs).The databases of PsycINFO(2000–2019),PubMed(2000–2019),EMBASE(2000–2019),CINAHL(2000–2019),Web of Science(2000–2019),and Scopus(2000–2019)were systematically searched.The clinical trials with RCT design were selected for final analysis.A total of nine RCTs were eligible and included in the review.Nine RCTs were included in the final analysis.Among them,six RCTs reported a significant reduction of AVH after repeated sessions of tDCS,whereas three RCTs did not show any advantage of active tDCS over sham tDCS.The current studies showed an overall decrease of approximately 28%of AVH after active tDCS and 10%after sham tDCS.The tDCS protocols targeting the sensorimotor frontal-parietal network showed greater treatment effects compared with the protocols targeting other regions.In this regard,cathodal tDCS over the left temporoparietal area showed inhibitory effects on AVHs.The most effective tDCS protocol on AVHs was twice-daily sessions(2 mA,20-minute duration)over 5 consecutive days(10 sessions)with the anode over the left dorsolateral prefrontal cortex and the cathode over the left temporal area.Some patient-specific and diseasespecific factors such as young age,nonsmoking status,and higher frequencies of AVHs seemed to be the predictors of treatment response.Taken together,the results of tDCS as an alternative treatment option for AVH show controversy among current literatures,since not all studies were positive.However,the studies targeting the same site of the brain showed that the tDCS could be a promising treatment option to reduce AVH.Further RCTs,with larger sample sizes,should be conducted to reach a conclusion on the
文摘In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.
基金Supported by Stem Cell Research Center of Golestan University of Medical Sciences(No.110480).
文摘AIM:To investigate the impact of niosome nanoparticles carrying umbelliprenin(UMB),an anti-angiogenic and anti-inflammatory plant compound,on the expression of vascular endothelial growth factor(VEGF-A)and connective tissue growth factor(CTGF)genes in a human retinal pigment epithelium(RPE)-like retina-derived cell line.METHODS:UMB-containing niosomes were created,optimized,and characterized.RPE-like cells were treated with free UMB and UMB-containing niosomes.The IC_(50)values of the treatments were determined using an MTT assay.Gene expression of VEGF-A and CTGF was evaluated using real-time polymerase chain reaction after RNA extraction and cDNA synthesis.Niosomes’characteristics,including drug entrapment efficiency,size,dispersion index,and zeta potential were assessed.Free UMB had an IC_(50)of 96.2μg/mL,while UMB-containing niosomes had an IC_(50)of 25μg/mL.RESULTS:Treatment with UMB-containing niosomes and free UMB resulted in a significant reduction in VEGF-A expression compared to control cells(P=0.001).Additionally,UMB-containing niosomes demonstrated a significant reduction in CTGF expression compared to control cells(P=0.05).However,there was no significant reduction in the expression of both genes in cells treated with free UMB.CONCLUSION:Both free UMB and niosome-encapsulated UMB inhibits VEGF-A and CTGF genes expression.However,the latter demonstrates significantly greater efficacy,potentially due to the lower UMB dosage and gradual delivery.These findings have implications for anti-angiogenesis therapeutic approaches targeting age-related macular degeneration.
文摘Despite modern medicine’s advancements,age-related neurological diseases like Alzheimer’s disease and Parkinson’s disease remain challenging due to high costs,side effects,and limited accessibility.Ayurveda,a traditional Indian medicine system,offers Kadha tea as a potential herbal option.This review explores Kadha’s components(basil(Ocimum basilicum L.),black pepper(Piper nigrum L.),Cinnamon(Cinnamomum verum J.Presl),ginger(Zingiber officinale Roscoe),and raisin(Vitis vinifera L.))and their interaction with various neurological disorders.Studies suggest Kadha exhibits anti-inflammatory,antioxidant,and antiviral properties,potentially impacting Alzheimer’s disease,Parkinson’s disease,neurotoxicity,neuroinflammation,and brain trauma.By focusing on specific disease mechanisms and Kadha’s intergrade effects,this review aims to elucidate its potential role in managing age-related neurological disorders.
文摘In this paper,the experimental investigation on the performance improvement of conventional stepped solar still is conducted.The steps are covered by the porous material to improve the performance of the conventional device and increase the evaporation rate.All the parameters,including the temperature on the glass surface,the water temperature inside the evaporation zone,and the amount of water produced in both conventional and modified stepped solar stills are measured and compared.The efficiency of two devices and their exergy efficiency have been calculated.Finally,the economic analysis of both devices has been done to check the economic feasibility of the modified device.The amount of freshwater generated during one day was 2244.4 and 3076.2 mL/m^(2),respectively for the conventional and modified stepped solar stills.As a result,the amount of water produced in one day by modified stepped solar still is 35.5% more than the conventional one.Also,the costs for the conventional and modified stepped solar stills have been calculated as 0.0359 and 0.029$/(L·m^(-2)),respectively.
文摘Exploitation of sustainable energy sources requires the use of unique conversion and storage systems,such as solar panels,batteries,fuel cells,and electronic equipment.Thermal load management of these energy conversion and storage systems is one of their challenges and concerns.In this article,the thermal management of these systems using thermoelectric modules is reviewed.The results show that by choosing the right option to remove heat from the hot side of the thermoelectric modules,it will be a suitable local cooling,and the thermoelectric modules increase the power and lifespan of the system by reducing the spot temperature.Thermoelectric modules were effective in reducing panel temperature.They increase the time to reach a temperature above 50℃ in batteries by 3 to 4 times.Also,in their integration with fuel cells,they increase the power density of the fuel cell.
文摘In order to reduce the sulfur compounds in diesel fuel,boron nitride(BN)has been used as a novel metal-free catalyst in the present research.This nanocatalyst was synthesized via template-free approach followed by heating treatment at 900℃ in nitrogen atmosphere that the characteristics of the sample were identified by the X-ray diffraction,Fourier-transform infrared spectroscopy,Raman spectroscopy,field emission scanning electron microscopy,transmission electron microscopy,atomic force microscopy,and N2 adsorption-desorption isotherms.The results of structural and morphological analysis represented that BN has been successfully synthesized.The efficacy of the main operating parameters on the process was studied by using response surface methodology based on the Box-Behnken design method.The prepared catalyst showed high efficiency in oxidative desulfurization of diesel fuel with initial sulfur content of 8040 mg·kg^(-1)S.From statistical analysis,a significant quadratic model was obtained to predict the sulfur removal as a function of efficient parameters.The maximum efficiency of 72.4%was achieved under optimized conditions at oxidant/sulfur molar ratio of 10.2,temperature of 71℃,reaction time of 113 min,and catalyst dosage of 0.36 g.Also,the reusability of the BN was studied,and the result showed little reduction in activity of the catalyst after 10 times regeneration.Moreover,a plausible mechanism was proposed for oxidation of sulfur compounds on the surface of the catalyst.The present study shows that BN materials can be selected as promising metal-free catalysts for desulfurization process.
文摘In this study,the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes（SWNTs）have been investigated.In both reactors,single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition（CCVD）of methane over Co-Mo/MgO nanocatalyst under two different operating conditions.The synthesized samples were characterized by TEM,TGA and Raman spectroscopy.It is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed bed.The quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of 0.71.Also,the yield of SWNTs in the fluidized bed was 92 wt%,while it was 78 wt%in the fixed bed.These advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.
文摘AIM： To compare the effectiveness of triple, standard quadruple and ampicillin-sulbactam-based quadruple therapies for Hpylori eradication in a comparative three-armed randomized clinical trial. METHODS： A total of 360 H pylori-positive patients suffering from dyspepsia and aging 24-79 years with a median age of 42 years were enrolled in the study and randomly allocated into the following three groups： group A （n = 120） received a standard 1-wk triple therapy （20 mg omeprazole b.i.d., 1000 mg amoxicillin b.i.d., 500 mg clarithromycin b.i.d.）, group B （n = 120） received a 10-d standard quadruple therapy （20 mg omeprazole b.i.d., 1000 mg amoxicillin b.i.d., 240 mg colloidal bismuth subcitrate b.i.d., and 500 mg metronidazole b.i.d.）, group C （n = 120） received the new protocol, i.e. 375 mg sultamicillin （225 mg ampicillin plus 150 mg sulbactam） b.i.d. （before breakfast and dinner）, instead of amoxicillin in the standard quadruple therapy for the same duration. Chi-square test with the consideration of P 〈 0.05 as significant was used to compare the eradication rates by intention-to-treat and per-protocol analyses in the three groups.RESULTS： The per-protocol eradication rate was 91.81% （101 patients from a total of 110） in group A, 85.84% （97 patients from a total of 113） in group B, and 92.85% （104 patients from a total of 112） in group C. The intention-to-treat eradication rate was 84.17% in group A, 80.83% in group B, and 86.67% in group C. The new protocol yielded the highest eradication rates by both per-protocol and intention-to-treat analyses followed by the standard triple and quadruple regimens, respectively. However, the differences were not statistically significant between the three groups. CONCLUSION： The results of this study provide further support for the equivalence of triple and quadruple therapies in terms of effectiveness, compliance and sideeffect profile when administered as first-line treatment for H pylori infection. Moreover, the new proto
文摘AIM: To investigate the cause of acute pancreatitis(AP) by conducting a thorough investigation of drugs and their possible etiological role.METHODS: We investigated the cause of AP in a large retrospective cohort of 613 adult patients admitted with AP at the Akershus University Hospital, Norway, from 2000 until 2009, who were evaluated with standard ward investigations. This group was compared with a prospectively evaluated group(n = 57) admitted from January 2010 until September 2010 who investigated more extensively using medical history and radiological assessment.RESULTS: The groups were comparable with regards to gender, age, comorbidity and severity. The most common etiology was bile stones and alcohol, occurring in 60% in both groups. The prospective group was examined more thoroughly with regards to the use of alcohol and medicines. An increased number of radiological investigations during hospital stay and at follow-up were also performed. A more extensive use of radiological evaluation did not increase the detection frequency of bile stones. In the prospective group, more than half of the patients had two or more possible causes of pancreatitis, being mostly a combination of bile stones and drugs. No possible cause was found in only 3.5% of these patients, compared with 29.7% in the retrospective group.CONCLUSION: A detailed medical history and extensive radiological evaluation may determine a possible etiology in almost all cases of AP. Many patients have several possible risk factors, and uncertainty remains in establishing the definitive etiology.
文摘The main purpose of this study is to survey numerically comparison of two- phase and single phase of heat transfer and flow field of copper-water nanofluid in a wavy channel. The computational fluid dynamics （CFD） prediction is used for heat transfer and flow prediction of the single phase and three different two-phase models （mixture, volume of fluid （VOF）, and Eulerian）. The heat transfer coefficient, temperature, and velocity distributions are investigated. The results show that the differences between the temperature fie].d in the single phase and two-phase models are greater than those in the hydrodynamic tleld. Also, it is found that the heat transfer coefficient predicted by the single phase model is enhanced by increasing the volume fraction of nanoparticles for all Reynolds numbers; while for the two-phase models, when the Reynolds number is low, increasing the volume fraction of nanoparticles will enhance the heat transfer coefficient in the front and the middle of the wavy channel, but gradually decrease along the wavy channel.
基金supported financially by the CAS President’s International Fellowship Initiative 2019(PIFI,No.2019PE0059)CAS-VPST Silk Road Science Fund 2021(133137KYSB20200034)INSF’s Project No.99010368。
文摘Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating fouling in the marine environment.Meanwhile,nanocomposite polymer coatings are a novel generation of antifouling coatings with merits of toxin-free chemical composition and ease of large-scale application.Nanomaterials such as nano-metals,nano-metal oxides,metal-organic frameworks,carbon-based nanostructures,MXene,and nanoclays have antibacterial and antifouling properties in the polymer coatings.Besides,these nanomaterials can improve the corrosion resistance,mechanical strength,weathering stability,and thermal resistance of the polymer coatings.Therefore,in this review paper,the antifouling nanocomposite coatings are introduced and antifouling mechanisms are discussed.This review explicitly indicates that the antifouling efficiency of the nanocomposite coatings depends on the properties of the polymer matrix,the inherent properties of the nanomaterials,the weight percent and the dispersion method of the nanomaterials within the coating matrix,and the chemicals used for modifying the surface of the nanomaterials;meanwhile,the hybrids of different nanomaterials and appropriate chemical agents could be used to improve the antifouling behavior of the prepared nanocomposites.Moreover,the theoretical studies are introduced to pave the way of researchers working on theantifouling coatings,and the importance of the theoretical studies and computational modeling along with the experimental research is notified to develop antifouling coatings with high efficiency.
文摘AIM： To compare the response of standard hepatitis B virus （HBV） vaccination between patients with chronic hepatitis C virus （HCV） infection and healthy individuals. METHODS： This is a prospective case-control study. A total of 38 patients with chronic HCV infection and 40 healthy controls were included. Vaccination was performed by injection of 20μg recombinant HBsAg into the deltoid muscle at mo 0,1 and 6. Anti-HBs concentration was determined 3 mo after the last dose and compared between the two groups. The response pattern was characterized as （1） high-response when the anti-HBs antibody titer was 〉 100 IU/L, （2） low-response when the titer was 10-100 IU/L. and （3） no-response when the titer was 〈 10 IU/L. RESULTS： In the patient group, there were 10/38 （26.3%） non-responders, 8/38 （21.1%） Iow-responders and 20/38 （52.6%） high-responders. The corresponding values in the control group were 2/40 （5.0%）, 7/40 （17.5%） and 31/40 （77.5%）, respectively. The response pattern was statistically different between the two groups. In multivariate analysis, smoking was a significant confounder, while HCV infection lost its significant correlation with lower antibody response. CONCLUSION： Patients with chronic HCV infection tend to respond weakly to HBV vaccination compared to healthy individuals, though this correlation is not independent according to multivariate analysis.
文摘Herein,nitrogen and sulfur co-doped carbon nanotubes(NS-CNT)adsorbents were synthesized via the chemical vapor deposition technique at 1000°C by employing the camphor,urea and sulfur trioxide pyridine.In this study,desulfurization of two types of mercaptans(dibenzothiophene(DBT)and tertiary butyl mercaptan(TBM)as nonlinear and linear forms of mercaptan)was studied.In this regard,a maximum capacity of NS-CNT was obtained as 106.9 and 79.4 mg/g and also the removal efficiencies of 98.6%and 88.3%were achieved after 4 h at 298K and 0.9 g of NS-CNT for DBT and TBM,respectively.Characterization of the NS-CNTs was carried out through exploiting scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and elemental analysis(CHN).The isotherm equilibrium data could be ascribed to the Freundlich nonlinear regression form and the kinetic data was fitted by nonlinear form of the pseudo second order model.The negative values of ΔS^(0),ΔH^(0) and ΔG^(0) specify that the adsorption of both types of mercaptans was a natural exothermic process with a reduced entropy.Maintenance of more than 96%of the adsorption capacity even after nine cycles suggest the NS-CNT as a superior adsorbent for mercaptans removal in the industry.Density functional theory(DFT)calculations were also performed to peruse the effects of S/N co-doping and carbon monovacancy defects in CNTs toward the adsorption of DBT and TBM.
基金This work was founded by SGL Carbon GmbH.The experimental part of the study was conducted at Department of Experimental Physics II,University of Augsburg.Special thanks to Wolfgang Muller and Michael Schulz for supporting the experimental works.
文摘Scanning electron microscopy shows that the microstructure,in particular the overall grain size,of chemical vapor deposited silicon carbide coatings depends on the deposition temperature.Sofar,the influence of the microstructure on the mechanical properties of such coatings is not well described in literature.To investigate the influence of the deposition temperature on the mechanical properties of the coating,nanoindentation is used in this work.Since the measurement results of nanoindentation can be affected by the substrate material,the contribution of the substrate material is taken into account utilizing a finite element model.The model is then employed to generate information about elastic and plastic properties of the coating by inverse simulation.To evaluate the fracture toughness of the coating,the generated material model is used in a cohesive-zone based formulation of the fracture process during indentation at higher loads.The results of this model allow determining the fracture toughness of silicon carbide coatings deposited at different temperatures.
