Carpal tunnel syndrome(CTS) is the most commonly diagnosed disabling condition of the upper extremities. It is the most commonly known and prevalent type of peripheral entrapment neuropathy that accounts for about 90%...Carpal tunnel syndrome(CTS) is the most commonly diagnosed disabling condition of the upper extremities. It is the most commonly known and prevalent type of peripheral entrapment neuropathy that accounts for about 90% of all entrapment neuropathies. This review aims to provide an outline of CTS by considering anat-omy, pathophysiology, clinical manifestation, diagnostic modalities and management of this common condition, with an emphasis on the diagnostic imaging evaluation.展开更多
Ankylosing spondylitis(AS) is a chronic inflammatory disease that affects 1% of the general population. As one of the most severe types of spondyloarthropathy, AS affects the spinal vertebrae and sacroiliac joints, ca...Ankylosing spondylitis(AS) is a chronic inflammatory disease that affects 1% of the general population. As one of the most severe types of spondyloarthropathy, AS affects the spinal vertebrae and sacroiliac joints, causing debilitating pain and loss of mobility. The goal of this review is to provide an overview of AS, from the pathophysiological changes that occur as the disease progresses, to genetic factors that are involved with its onset. Considering the high prevalence in the population, and the debilitating life changes that occur as a result of the disease, a strong emphasis is placed on the diagnostic imaging methods that are used to detect this condition, as well as several treatment methods that could improve the health of individuals diagnosed with AS.展开更多
A field study was conducted at the Agricultural Research Farm of Razi University, Kermanshah, Iran to investigate the effects of phosphate biofertilizer, row spacing and plant density on corn yield and weed growth. Th...A field study was conducted at the Agricultural Research Farm of Razi University, Kermanshah, Iran to investigate the effects of phosphate biofertilizer, row spacing and plant density on corn yield and weed growth. The experiment was a factorial with three factors arranged in a randomized complete block design with three replications. The first factor was phosphate biofertilizer (inoculation and non-inoculation), the second was row spacing (conventional (75 cm) and reduced (50 cm)) and the third was plant density (66,666 plants·ha–1 (conventional plant density) 83,333 and 99,999 plants·ha–1 (1.25 and 1.5 times the conventional plant density, respectively)). Results indicated that corn yield and weed growth were significantly influenced by row spacing and plant density. So that, corn yield improved and weed biomass diminished in response to increasing plant density and decreasing row spacing. However, phosphate biofertilizer had no significant effect on corn yield, whereas, weed biomass was notably increased when phosphate biofertilizer was applied. Overall, this study revealed that both yield and weed control in corn field can be improved by alteration of the planting arrangement.展开更多
In this communication, the impacts of adding SDS （sodium dodecyl sulfate）, TBAF （tetra-n-butylammonlum tluorloe） ano the mixture of SDS ＋ TBAF on the main kinetic parameters of CO2 hydrate formation （induction t...In this communication, the impacts of adding SDS （sodium dodecyl sulfate）, TBAF （tetra-n-butylammonlum tluorloe） ano the mixture of SDS ＋ TBAF on the main kinetic parameters of CO2 hydrate formation （induction time, the quantity and rate of gas uptake, and storage capacity） were investigated. The tests were performed under stirring conditions at T = 5 ℃ and P = 3.8 MPa in a 169 cm3 batch reactor. The results show that adding SDS with a concentration of 400 ppm, TBAF with a concentration of l-5 wt%, and the mixture of SDS ＋ TBAF, would increase the storage capacity of CO2 hydrate and the quantity of gas uptake, and decrease the induction time of hydrate formation process. The addition of 5 wt% of TBAF and 400 ppm of SDS would increase the CO2 hydrate storage capacity by 86.1% and 81.6%, respectively, compared to pure water. Investigation of the impact of SDS, TBAF and their mixture on the rate of gas uptake indicates that the mixture of SDS ＋ TBAF does not have a significant effect on the rate of gas uptake during hydrate formation process.展开更多
NiMo-based materials have been identified as potential candidates of Pt/C electrocatalysts for hydrogen evolution reaction(HER)due to appropriate binding energy to hydrogen,and good resistance to corrosive environment...NiMo-based materials have been identified as potential candidates of Pt/C electrocatalysts for hydrogen evolution reaction(HER)due to appropriate binding energy to hydrogen,and good resistance to corrosive environments.However,little work has been carried out to enhance the catalytic performance in large-scale water-alkali electrolysis.The NoMo amorphous coating,as a highefficient and cost-effective catalyst toward HER,was synthesized by a facile electrodeposition strategy in this study.The effects of the pH value of electrolyte on the structure and HER activity of NiMo coating were investigated.The as-prepared NiMo_((pH10))exhibited the highest HER activity with overpotentials of 63.9 and 157.1 mV(vs.RHE,with 80%potential drop due to electrical resistance(iR)compensation)at the current density of-10 mA·cm^(-2)and-100 mA·cm^(-2).This NiMo_((pH10))coating also had excellent long-term durability of up to100 h stable operation under the constant current density of-100 mA·cm^(-2).The rapid HER kinetics and outstanding endurance can be ascribed to the NiMo compact coating with amorphous structures as well as good contact between NiMo coating and Ni foam substrate,endowing it grand feasibility in practical industrial applications.展开更多
The interest in biodegradable polymer-matrix nanocomposites with bone regeneration potential has been increasing in recent years.In the present work,a solvothermal process is introduced to prepare hydroxyapatite(HA)na...The interest in biodegradable polymer-matrix nanocomposites with bone regeneration potential has been increasing in recent years.In the present work,a solvothermal process is introduced to prepare hydroxyapatite(HA)nanorod-reinforced polycaprolactone in-situ.A non-aqueous polymer solution containing calcium and phosphorous precursors is prepared and processed in a closed autoclave at different temperatures in the range of 60-150℃.Hydroxyapatite nanorods with varying aspect ratios are formed depending on the processing temperature.X-ray diffraction analysis and field-emission scanning electron microscopy indicate that the HA nanorods are semi-crystalline.Energy-dispersive Xray spectroscopy and Fourier transform infrared spectrometry determine that the ratio of calcium to phosphorous increases as the processing temperature increases.To evaluate the effect of in-situ processing on the mechanical properties of the nanocomposites,highly porous scaffolds(>90%)containing HA nanorods are prepared by employing freeze drying and salt leaching techniques.It is shown that the elastic modulus and strength of the nanocomposites prepared by the in-situ method is superior(~15%)to those of the ex-situ samples(blended HA nanorods with the polymer solution).The enhanced bone regeneration potential of the nanocomposites is shown via an in vitro bioactivity assay in a saturated simulated body fluid.An improved cell viability and proliferation is also shown by employing(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide)(MTT)assay in human osteosarcoma cell lines.The prepared scaffolds with in vitro regeneration capacity could be potentially useful for orthopaedic applications and maxillofacial surgery.展开更多
High energy gas fracturing is a simple approach of applying high pressure gas to stimulate wells by gen- erating several radial cracks without creating any other damages to the wells. In this paper, a numerical algori...High energy gas fracturing is a simple approach of applying high pressure gas to stimulate wells by gen- erating several radial cracks without creating any other damages to the wells. In this paper, a numerical algorithm is proposed to quantitatively simulate propagation of these fractures around a pressurized hole as a quasi-static phenomenon. The gas flow through the cracks is assumed as a one-dimensional transient flow, governed by equations of conservation of mass and momentum. The fractured medium is modeled with the extended finite element method, and the stress intensity factor is calculated by the simple, though sufficiently accurate, displacement ex- trapolation method. To evaluate the proposed algorithm, two field tests are simulated and the unknown parameters are determined through calibration. Sensitivity analyses are performed on the main effective parameters. Considering that the level of uncertainty is very high in these types of engineering problems, the results show a good agreement with the experimental data. They are also consistent with the theory that the final crack length is mainly determined by the gas pressure rather than the initial crack length produced by the stress waves.展开更多
Soil particle size distribution(PSD) is a fundamental physical property affecting other soil properties. Characterizing spatial variability of soil texture is very important in environmental research. The objectives o...Soil particle size distribution(PSD) is a fundamental physical property affecting other soil properties. Characterizing spatial variability of soil texture is very important in environmental research. The objectives of this work were: 1) to partition PSD of 75 soil samples, collected from a flat field in the University of Guilan, Iran, into two scaling domains using a piecewise fractal model to evaluate the relationships between fractal dimensions of scaling domains and soil clay, silt, and sand fractions and 2) to assess the potential of fractal parameters as an index used in a geostatistical approach reflecting the spatial variability of soil texture. Features of PSD of soil samples were studied using fractal geometry, and geostatistical techniques were used to characterize the spatial variability of fractal and soil textural parameters. There were two scaling domains for the PSD of soil samples. The fractal dimensions of these two scaling domains(D_1 and D_2) were then used to characterize different ranges of soil particle sizes and their relationships to the soil textural parameters. There was a positive correlation between D_1 and clay content(R^2= 0.924), a negative correlation between D_1 and silt content(R^2= 0.801), and a negative correlation between D_2 and sand content(R^2= 0.913). The geometric mean diameter of soil particles had a negative correlation with D_1(R^2= 0.569) and D_2(R^2= 0.682). Semivariograms of fractal dimensions and soil textural parameters were calculated and the maps of spatial variation of D_1 and D_2 and soil PSD parameters were provided using ordinary kriging. The results showed that there were also spatial correlations between D_1 and D_2 and particle size fractions.According to the semivariogram models and validation parameters, the fractal parameters had powerful spatial structure and could better describe the spatial variability of soil texture.展开更多
By combining DEM （Discrete Element Method） and FEM （Finite Element Method）, a model is established to simulate the breakage of twodimensional sharp-edge particles, in which the simulated particles are assumed to h...By combining DEM （Discrete Element Method） and FEM （Finite Element Method）, a model is established to simulate the breakage of twodimensional sharp-edge particles, in which the simulated particles are assumed to have no cracks. Particles can, however, crush during different stages of the numerical analysis, if stress-based breakage criteria are fulfilled inside the particles. With this model, it is possible to study the influence of particle breakage on macro- and micro-mechanical behavior of simulated angular materials. Two series of tests, with and without breakable particles, are simulated under different confining pressures based on conditions of biaxial tests. The results, presented in terms of micromechanical behavior for different confining pressures, are compared with macroparameters. The influence of particle breakage on microstructure of sharp-edge materials is discussed and the related confining pressure effects are investigated. Breakage of particles in rockfill materials are shown to reduce the anisotropy coefficients of the samples and therefore their strength and dilation behaviors.展开更多
AIM： To examine the frequency of antibiotic resistance in Iranian Helicobacter pylori （ H pylon） strains isolated from two major hospitals in Tehran.METHODS： Examination of antibiotic resistance was performed on 1...AIM： To examine the frequency of antibiotic resistance in Iranian Helicobacter pylori （ H pylon） strains isolated from two major hospitals in Tehran.METHODS： Examination of antibiotic resistance was performed on 120 strains by modified disc diffusion test and PCR-RFLP methods. In addition, in order to identify the possible causes of the therapeutic failure in Iran, we also determined the resistance of these strains to the most commonly used antibiotics （metronidazole, amoxicillin, and tetracycline） by modified disc diffusion test. RESULTS： According to modified disc diffusion test, 1.6% of the studied strains were resistant to amoxicillin, 16.7% to clarithromycin, 57.5% to metronidazole, and there was no resistance to tetracycline. Of the clarithromycin resistant strains, 73.68% had the A2143G mutation in the 23SrRlVA gene, 21.05% A2142C, and 5.26% A2142G. None of the sensitive strains were positive for any of the three point mutations. Of the metronidazole resistant strains, deletion in rdxA gene was studied and detected in only 6 （5%） of the antibiogram-based resistant strains. None of the metronidazole sensitive strains possessed rdxA gene deletion. CONCLUSION： These data show that despite the fact that clarithromycin has not yet been introduced to the Iranian drug market as a generic drug, nearly 20% rate of resistance alerts toward the frequency of macrolide resistance strains, which may be due to the widespread prescription of erythromycin in Iran. rdxA gene inactivation, if present in Iranian Hpyloristrains, may be due to other genetic defects rather than gene deletion.展开更多
TiO_2 nanoparticles（TiO_2 NPs） worked as an efficient heterogeneous catalyst in a one-pot,three-component,and solvent free Mannich reaction;producing variousβ-aminocarbonyls in good yields,and with good stereoselec...TiO_2 nanoparticles（TiO_2 NPs） worked as an efficient heterogeneous catalyst in a one-pot,three-component,and solvent free Mannich reaction;producing variousβ-aminocarbonyls in good yields,and with good stereoselectivities.The catalyst was easily separated from the reaction mixture and was recycled four times with no significant loss of its catalytic activity.展开更多
Analysis of long-term EEG signals needs that it be segmented into pseudo stationary epochs. That work is done by regarding to statistical characteristics of a signal such as amplitude and frequency. Time series measur...Analysis of long-term EEG signals needs that it be segmented into pseudo stationary epochs. That work is done by regarding to statistical characteristics of a signal such as amplitude and frequency. Time series measured in real world is frequently non-stationary and to extract important information from the measured time series it is significant to utilize a filter or smoother as a pre-processing step. In the proposed approach, the signal is initially filtered by Moving Average (MA) or Savitzky-Golay filter to attenuate its short-term variations. Then, changes of the amplitude or frequency of the signal is calculated by Modified Varri method which is an acceptable algorithm for segmenting a signal. By using synthetic and real EEG data, the proposed methods are compared with original approach (simple Modified Varri). The simulation results indicate the absolute advantage of the proposed methods.展开更多
Fe3O4/CMK-3 was prepared by impregnation and used as a catalyst for the direct hydroxylation of benzene to phenol with hydro-gen peroxide. The iron species in the prepared catalyst was Fe3O4 because of the partial red...Fe3O4/CMK-3 was prepared by impregnation and used as a catalyst for the direct hydroxylation of benzene to phenol with hydro-gen peroxide. The iron species in the prepared catalyst was Fe3O4 because of the partial reduction of iron(III) to iron(II) on the surface of CMK-3. The high catalytic activity of the catalyst arises from the formation of Fe3O4 on the surface of CMK-3 and the high selectivity for phenol is attributed to the consumption of excess hydroxyl radicals by CMK-3. The effect of temperature,reaction time,volume of H2O2,and amount of catalyst on the catalytic performance of the prepared catalyst were investigated. Under optimized conditions,the catalyst showed excellent catalytic performance for the hydroxylation of benzene to phenol and 18% benzene conversion was achieved with 92% selectivity for phenol and with a TOF value of 8.7 h-1. The stability of catalyst was investigated by determining its activity after the fourth run and it was found to have decreased to 80% of the fresh catalyst's activity.展开更多
Many properties of fruit are influenced by plant nutrition. Fruit firmness is one of the most important fruit characteristics and determines post-harvest life of the fruit, in recent decades, artificial intelligence s...Many properties of fruit are influenced by plant nutrition. Fruit firmness is one of the most important fruit characteristics and determines post-harvest life of the fruit, in recent decades, artificial intelligence systems were employed for developing predictive models to estimate and predict many agriculture processes. In the present study, the predictive capabilities of multiple linear regressions （MLR） and artificial neural networks （ANNs） are evaluated to estimate fruit firmness in six months, including each of nutrients concentrations （nitrogen （N）, potassium （K）, calcium （Ca） and magnesium （Mg）） alone （P1）, com- bination of nutrients concentrations （P2）, nutrient concentration ratios alone （P3）, and combination of nutrient concentrations and nutrient concentration ratios （P4）. The results showed that MLR model estimated fruit firmness more accuracy than ANN model in three datasets （P1, P2 and P4）. However, the application of P3 （N/Ca ratio） as the input dataset in ANN model improved the prediction of fruit firmness than the MLR model. Correlation coefficient and root mean squared error （RMSE） were 0.850 and 0.539 between the measured and the estimated data by the ANN model, respectively. Generally, the ANN model showed greater potential in determining the relationship between 6-mon-fruit firmness and nutrients concentration.展开更多
Data Envelopment Analysis （DEA） is a mathematical tech- nique to assess relative efficiencies of decision making units （DMUs）. The efficiency of 14 Iranian forest companies and forest management units was investig...Data Envelopment Analysis （DEA） is a mathematical tech- nique to assess relative efficiencies of decision making units （DMUs）. The efficiency of 14 Iranian forest companies and forest management units was investigated in 2010. Efficiency of the companies was esti- mated by using a traditional DEA model and a two-stage DEA model. Traditional DEA models consider all DMU activities as a black box and ignore the intermediate products, while two-stage models address inter- mediate processes. LINGO software was used for analysis. Overall pro- duction was divided into to processes for analyses by the two-stage model, timber harvest and marketing. Wilcoxon＇s signed-rank test was used to identify the differences of average efficiency in the harvesting and marketing sub-process. Weak performance in the harvesting sub-process was the cause of low efficiency in 2010. Companies such as Neka Chob and Kelardasht proved efficient at timber harvest, and Neka Chob forest company scored highest in overall efficiency. Finally, the reference units identified according to the results of two-stage DEA analysis.展开更多
Rock mass classification systems are the very important part for underground projects and rock mass rating(RMR) is one of the most commonly applied classification systems in numerous civil and mining projects. The typ...Rock mass classification systems are the very important part for underground projects and rock mass rating(RMR) is one of the most commonly applied classification systems in numerous civil and mining projects. The type of rock mass consisting of an interbedding of strong and weak layers poses difficulties and uncertainties for determining the RMR. For this, the present paper uses the concept of rock bolt supporting factor(RSF) for modification of RMR system to be used in such rock mass types. The proposed method also demonstrates the importance of rock bolting practice in such rock masses. The geological parameters of the Shemshak Formation of the Alborz Tunnel in Iran are used as case examples for development of the theoretical approach.展开更多
The Firefly Algorithm(FA)is a highly efficient population-based optimization technique developed by mimicking the flashing behavior of fireflies when mating.This article proposes a method based on Differential Evoluti...The Firefly Algorithm(FA)is a highly efficient population-based optimization technique developed by mimicking the flashing behavior of fireflies when mating.This article proposes a method based on Differential Evolution(DE)/current-to-best/1 for enhancing the FA's movement process.The proposed modification increases the global search ability and the convergence rates while maintaining a balance between exploration and exploitation by deploying the global best solution.However,employing the best solution can lead to premature algorithm convergence,but this study handles this issue using a loop adjacent to the algorithm's main loop.Additionally,the suggested algorithm’s sensitivity to the alpha parameter is reduced compared to the original FA.The GbFA surpasses both the original and five-version of enhanced FAs in finding the optimal solution to 30 CEC2014 real parameter benchmark problems with all selected alpha values.Additionally,the CEC 2017 benchmark functions and the eight engineering optimization challenges are also utilized to evaluate GbFA’s efficacy and robustness on real-world problems against several enhanced algorithms.In all cases,GbFA provides the optimal result compared to other methods.Note that the source code of the GbFA algorithm is publicly available at https://www.optim-app.com/projects/gbfa.展开更多
Tomato is one of the extensively consumed vegetable crops worldwide. The regular consumption of tomato decreases the incidence of chronic degenerative diseases such as certain types of cancer and cardiovascular diseas...Tomato is one of the extensively consumed vegetable crops worldwide. The regular consumption of tomato decreases the incidence of chronic degenerative diseases such as certain types of cancer and cardiovascular diseases. The objective of this study was to find an appropriate method that not only reduces tomatoes decay, but also maintains its post-harvest quality. A factorial experiment based on randomized complete block design with three replications was conducted to evaluate effects of ultraviolet（UV）-C and CaCl_2 applications on tomato during storage. The traits studied included ethylene, polygalacturonase（PG） activity, pectin methyl esterase（PME） activity, firmness, total phenol content, and fungal-induced decay were measured weekly during 35 days of storage. Both UV-C and CaCl_2 treatments had positive effects on tomato quality as compared to control treatment. The 3 and 4.5 k J m^（-2） levels of UV-C and 2% CaCl_2 had positive effects on quality characteristics, respectivly. Fruits treated by UV-C and CaCl_2 had higher phenol and firmness, and less PME activity, PG activity, ethylene production, and decay than the control fruits. In conclusion, increasing in storage duration significantly affected the fruits quality by increasing in ethylene, PME activity, PG activity, decay and decreasing the phenol content and firmness. But UV-C and CaCl_2 led to significant decrease in this adverse impact relative to control treatment.展开更多
BACKGROUND： Analgesic and wound-healing effects of cinnamon, a widely used spice, have been shown in laboratory rats. However, we found no human studies in this area. OBJECTIVE： The aim of this study was to assess t...BACKGROUND： Analgesic and wound-healing effects of cinnamon, a widely used spice, have been shown in laboratory rats. However, we found no human studies in this area. OBJECTIVE： The aim of this study was to assess the effect of cinnamon on perineal pain and healing of episiotomy incision. DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS： In this double-blind, randomized, placebo-controlled trial, 144 postpartum women were allocated into two groups, using stratified block randomization, 1 h after completion of episiotomy repair. They received cinnamon or placebo ointment, 2 mL every 12 h for 10 d. MAIN OUTCOME MEASURES： Perineal pain and wound healing were assessed using visual analogue scale （0-10）and Redness, Edema, Ecchymosis, Discharge, Approximation scale （0-15）, respectively. General linear model was used to compare the groups on the outcomes adjusted for baseline values and stratified factors. RESULTS： Follow-up rate was 100% up to the 8 h time point in both groups, and 86% （62 of 72） in the cinnamon group and 85% （61 of 72） in the placebo group at day 10-11 after delivery. Pain score in the cinnamon group was significantly lower than that in the placebo group at （4±1） h （adjusted difference： -0.6, 95% confidence interval： -1.0 to -0.2） and （8＋1） h （-0.9, -1.4 to -0.3） after intervention, and on the 10-11th day after delivery （-1.4, -2.0 to -0.7）. Also the cinnamon group showed significantly more improvement than the control group in healing score at （8±1） h （-0.2, -0.4 to -0.04） and the 10-11th day after delivery （-1.6, -2.0 to -1.1）. CONCLUSION： Cinnamon can be used for reducing perineal pain and improving healing of episiotomy incision.展开更多
文摘Carpal tunnel syndrome(CTS) is the most commonly diagnosed disabling condition of the upper extremities. It is the most commonly known and prevalent type of peripheral entrapment neuropathy that accounts for about 90% of all entrapment neuropathies. This review aims to provide an outline of CTS by considering anat-omy, pathophysiology, clinical manifestation, diagnostic modalities and management of this common condition, with an emphasis on the diagnostic imaging evaluation.
文摘Ankylosing spondylitis(AS) is a chronic inflammatory disease that affects 1% of the general population. As one of the most severe types of spondyloarthropathy, AS affects the spinal vertebrae and sacroiliac joints, causing debilitating pain and loss of mobility. The goal of this review is to provide an overview of AS, from the pathophysiological changes that occur as the disease progresses, to genetic factors that are involved with its onset. Considering the high prevalence in the population, and the debilitating life changes that occur as a result of the disease, a strong emphasis is placed on the diagnostic imaging methods that are used to detect this condition, as well as several treatment methods that could improve the health of individuals diagnosed with AS.
文摘A field study was conducted at the Agricultural Research Farm of Razi University, Kermanshah, Iran to investigate the effects of phosphate biofertilizer, row spacing and plant density on corn yield and weed growth. The experiment was a factorial with three factors arranged in a randomized complete block design with three replications. The first factor was phosphate biofertilizer (inoculation and non-inoculation), the second was row spacing (conventional (75 cm) and reduced (50 cm)) and the third was plant density (66,666 plants·ha–1 (conventional plant density) 83,333 and 99,999 plants·ha–1 (1.25 and 1.5 times the conventional plant density, respectively)). Results indicated that corn yield and weed growth were significantly influenced by row spacing and plant density. So that, corn yield improved and weed biomass diminished in response to increasing plant density and decreasing row spacing. However, phosphate biofertilizer had no significant effect on corn yield, whereas, weed biomass was notably increased when phosphate biofertilizer was applied. Overall, this study revealed that both yield and weed control in corn field can be improved by alteration of the planting arrangement.
基金financial support from the Iran National Science Foundation
文摘In this communication, the impacts of adding SDS （sodium dodecyl sulfate）, TBAF （tetra-n-butylammonlum tluorloe） ano the mixture of SDS ＋ TBAF on the main kinetic parameters of CO2 hydrate formation （induction time, the quantity and rate of gas uptake, and storage capacity） were investigated. The tests were performed under stirring conditions at T = 5 ℃ and P = 3.8 MPa in a 169 cm3 batch reactor. The results show that adding SDS with a concentration of 400 ppm, TBAF with a concentration of l-5 wt%, and the mixture of SDS ＋ TBAF, would increase the storage capacity of CO2 hydrate and the quantity of gas uptake, and decrease the induction time of hydrate formation process. The addition of 5 wt% of TBAF and 400 ppm of SDS would increase the CO2 hydrate storage capacity by 86.1% and 81.6%, respectively, compared to pure water. Investigation of the impact of SDS, TBAF and their mixture on the rate of gas uptake indicates that the mixture of SDS ＋ TBAF does not have a significant effect on the rate of gas uptake during hydrate formation process.
基金financially supported by the National Natural Science Foundation of China (No.51771131)
文摘NiMo-based materials have been identified as potential candidates of Pt/C electrocatalysts for hydrogen evolution reaction(HER)due to appropriate binding energy to hydrogen,and good resistance to corrosive environments.However,little work has been carried out to enhance the catalytic performance in large-scale water-alkali electrolysis.The NoMo amorphous coating,as a highefficient and cost-effective catalyst toward HER,was synthesized by a facile electrodeposition strategy in this study.The effects of the pH value of electrolyte on the structure and HER activity of NiMo coating were investigated.The as-prepared NiMo_((pH10))exhibited the highest HER activity with overpotentials of 63.9 and 157.1 mV(vs.RHE,with 80%potential drop due to electrical resistance(iR)compensation)at the current density of-10 mA·cm^(-2)and-100 mA·cm^(-2).This NiMo_((pH10))coating also had excellent long-term durability of up to100 h stable operation under the constant current density of-100 mA·cm^(-2).The rapid HER kinetics and outstanding endurance can be ascribed to the NiMo compact coating with amorphous structures as well as good contact between NiMo coating and Ni foam substrate,endowing it grand feasibility in practical industrial applications.
基金AS wish to thank funding support from Sharif University of Technology(SUT,No.G930305)Iran National Science Foundation(INSF No.95-S-48740).
文摘The interest in biodegradable polymer-matrix nanocomposites with bone regeneration potential has been increasing in recent years.In the present work,a solvothermal process is introduced to prepare hydroxyapatite(HA)nanorod-reinforced polycaprolactone in-situ.A non-aqueous polymer solution containing calcium and phosphorous precursors is prepared and processed in a closed autoclave at different temperatures in the range of 60-150℃.Hydroxyapatite nanorods with varying aspect ratios are formed depending on the processing temperature.X-ray diffraction analysis and field-emission scanning electron microscopy indicate that the HA nanorods are semi-crystalline.Energy-dispersive Xray spectroscopy and Fourier transform infrared spectrometry determine that the ratio of calcium to phosphorous increases as the processing temperature increases.To evaluate the effect of in-situ processing on the mechanical properties of the nanocomposites,highly porous scaffolds(>90%)containing HA nanorods are prepared by employing freeze drying and salt leaching techniques.It is shown that the elastic modulus and strength of the nanocomposites prepared by the in-situ method is superior(~15%)to those of the ex-situ samples(blended HA nanorods with the polymer solution).The enhanced bone regeneration potential of the nanocomposites is shown via an in vitro bioactivity assay in a saturated simulated body fluid.An improved cell viability and proliferation is also shown by employing(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide)(MTT)assay in human osteosarcoma cell lines.The prepared scaffolds with in vitro regeneration capacity could be potentially useful for orthopaedic applications and maxillofacial surgery.
基金support of Iran National Science Foundation is also gratefully appreciated
文摘High energy gas fracturing is a simple approach of applying high pressure gas to stimulate wells by gen- erating several radial cracks without creating any other damages to the wells. In this paper, a numerical algorithm is proposed to quantitatively simulate propagation of these fractures around a pressurized hole as a quasi-static phenomenon. The gas flow through the cracks is assumed as a one-dimensional transient flow, governed by equations of conservation of mass and momentum. The fractured medium is modeled with the extended finite element method, and the stress intensity factor is calculated by the simple, though sufficiently accurate, displacement ex- trapolation method. To evaluate the proposed algorithm, two field tests are simulated and the unknown parameters are determined through calibration. Sensitivity analyses are performed on the main effective parameters. Considering that the level of uncertainty is very high in these types of engineering problems, the results show a good agreement with the experimental data. They are also consistent with the theory that the final crack length is mainly determined by the gas pressure rather than the initial crack length produced by the stress waves.
文摘Soil particle size distribution(PSD) is a fundamental physical property affecting other soil properties. Characterizing spatial variability of soil texture is very important in environmental research. The objectives of this work were: 1) to partition PSD of 75 soil samples, collected from a flat field in the University of Guilan, Iran, into two scaling domains using a piecewise fractal model to evaluate the relationships between fractal dimensions of scaling domains and soil clay, silt, and sand fractions and 2) to assess the potential of fractal parameters as an index used in a geostatistical approach reflecting the spatial variability of soil texture. Features of PSD of soil samples were studied using fractal geometry, and geostatistical techniques were used to characterize the spatial variability of fractal and soil textural parameters. There were two scaling domains for the PSD of soil samples. The fractal dimensions of these two scaling domains(D_1 and D_2) were then used to characterize different ranges of soil particle sizes and their relationships to the soil textural parameters. There was a positive correlation between D_1 and clay content(R^2= 0.924), a negative correlation between D_1 and silt content(R^2= 0.801), and a negative correlation between D_2 and sand content(R^2= 0.913). The geometric mean diameter of soil particles had a negative correlation with D_1(R^2= 0.569) and D_2(R^2= 0.682). Semivariograms of fractal dimensions and soil textural parameters were calculated and the maps of spatial variation of D_1 and D_2 and soil PSD parameters were provided using ordinary kriging. The results showed that there were also spatial correlations between D_1 and D_2 and particle size fractions.According to the semivariogram models and validation parameters, the fractal parameters had powerful spatial structure and could better describe the spatial variability of soil texture.
文摘By combining DEM （Discrete Element Method） and FEM （Finite Element Method）, a model is established to simulate the breakage of twodimensional sharp-edge particles, in which the simulated particles are assumed to have no cracks. Particles can, however, crush during different stages of the numerical analysis, if stress-based breakage criteria are fulfilled inside the particles. With this model, it is possible to study the influence of particle breakage on macro- and micro-mechanical behavior of simulated angular materials. Two series of tests, with and without breakable particles, are simulated under different confining pressures based on conditions of biaxial tests. The results, presented in terms of micromechanical behavior for different confining pressures, are compared with macroparameters. The influence of particle breakage on microstructure of sharp-edge materials is discussed and the related confining pressure effects are investigated. Breakage of particles in rockfill materials are shown to reduce the anisotropy coefficients of the samples and therefore their strength and dilation behaviors.
基金Supported by a Research Grant From the Pasteur Institute of Iran, No.198
文摘AIM： To examine the frequency of antibiotic resistance in Iranian Helicobacter pylori （ H pylon） strains isolated from two major hospitals in Tehran.METHODS： Examination of antibiotic resistance was performed on 120 strains by modified disc diffusion test and PCR-RFLP methods. In addition, in order to identify the possible causes of the therapeutic failure in Iran, we also determined the resistance of these strains to the most commonly used antibiotics （metronidazole, amoxicillin, and tetracycline） by modified disc diffusion test. RESULTS： According to modified disc diffusion test, 1.6% of the studied strains were resistant to amoxicillin, 16.7% to clarithromycin, 57.5% to metronidazole, and there was no resistance to tetracycline. Of the clarithromycin resistant strains, 73.68% had the A2143G mutation in the 23SrRlVA gene, 21.05% A2142C, and 5.26% A2142G. None of the sensitive strains were positive for any of the three point mutations. Of the metronidazole resistant strains, deletion in rdxA gene was studied and detected in only 6 （5%） of the antibiogram-based resistant strains. None of the metronidazole sensitive strains possessed rdxA gene deletion. CONCLUSION： These data show that despite the fact that clarithromycin has not yet been introduced to the Iranian drug market as a generic drug, nearly 20% rate of resistance alerts toward the frequency of macrolide resistance strains, which may be due to the widespread prescription of erythromycin in Iran. rdxA gene inactivation, if present in Iranian Hpyloristrains, may be due to other genetic defects rather than gene deletion.
文摘TiO_2 nanoparticles（TiO_2 NPs） worked as an efficient heterogeneous catalyst in a one-pot,three-component,and solvent free Mannich reaction;producing variousβ-aminocarbonyls in good yields,and with good stereoselectivities.The catalyst was easily separated from the reaction mixture and was recycled four times with no significant loss of its catalytic activity.
文摘Analysis of long-term EEG signals needs that it be segmented into pseudo stationary epochs. That work is done by regarding to statistical characteristics of a signal such as amplitude and frequency. Time series measured in real world is frequently non-stationary and to extract important information from the measured time series it is significant to utilize a filter or smoother as a pre-processing step. In the proposed approach, the signal is initially filtered by Moving Average (MA) or Savitzky-Golay filter to attenuate its short-term variations. Then, changes of the amplitude or frequency of the signal is calculated by Modified Varri method which is an acceptable algorithm for segmenting a signal. By using synthetic and real EEG data, the proposed methods are compared with original approach (simple Modified Varri). The simulation results indicate the absolute advantage of the proposed methods.
文摘Fe3O4/CMK-3 was prepared by impregnation and used as a catalyst for the direct hydroxylation of benzene to phenol with hydro-gen peroxide. The iron species in the prepared catalyst was Fe3O4 because of the partial reduction of iron(III) to iron(II) on the surface of CMK-3. The high catalytic activity of the catalyst arises from the formation of Fe3O4 on the surface of CMK-3 and the high selectivity for phenol is attributed to the consumption of excess hydroxyl radicals by CMK-3. The effect of temperature,reaction time,volume of H2O2,and amount of catalyst on the catalytic performance of the prepared catalyst were investigated. Under optimized conditions,the catalyst showed excellent catalytic performance for the hydroxylation of benzene to phenol and 18% benzene conversion was achieved with 92% selectivity for phenol and with a TOF value of 8.7 h-1. The stability of catalyst was investigated by determining its activity after the fourth run and it was found to have decreased to 80% of the fresh catalyst's activity.
文摘Many properties of fruit are influenced by plant nutrition. Fruit firmness is one of the most important fruit characteristics and determines post-harvest life of the fruit, in recent decades, artificial intelligence systems were employed for developing predictive models to estimate and predict many agriculture processes. In the present study, the predictive capabilities of multiple linear regressions （MLR） and artificial neural networks （ANNs） are evaluated to estimate fruit firmness in six months, including each of nutrients concentrations （nitrogen （N）, potassium （K）, calcium （Ca） and magnesium （Mg）） alone （P1）, com- bination of nutrients concentrations （P2）, nutrient concentration ratios alone （P3）, and combination of nutrient concentrations and nutrient concentration ratios （P4）. The results showed that MLR model estimated fruit firmness more accuracy than ANN model in three datasets （P1, P2 and P4）. However, the application of P3 （N/Ca ratio） as the input dataset in ANN model improved the prediction of fruit firmness than the MLR model. Correlation coefficient and root mean squared error （RMSE） were 0.850 and 0.539 between the measured and the estimated data by the ANN model, respectively. Generally, the ANN model showed greater potential in determining the relationship between 6-mon-fruit firmness and nutrients concentration.
文摘Data Envelopment Analysis （DEA） is a mathematical tech- nique to assess relative efficiencies of decision making units （DMUs）. The efficiency of 14 Iranian forest companies and forest management units was investigated in 2010. Efficiency of the companies was esti- mated by using a traditional DEA model and a two-stage DEA model. Traditional DEA models consider all DMU activities as a black box and ignore the intermediate products, while two-stage models address inter- mediate processes. LINGO software was used for analysis. Overall pro- duction was divided into to processes for analyses by the two-stage model, timber harvest and marketing. Wilcoxon＇s signed-rank test was used to identify the differences of average efficiency in the harvesting and marketing sub-process. Weak performance in the harvesting sub-process was the cause of low efficiency in 2010. Companies such as Neka Chob and Kelardasht proved efficient at timber harvest, and Neka Chob forest company scored highest in overall efficiency. Finally, the reference units identified according to the results of two-stage DEA analysis.
文摘Rock mass classification systems are the very important part for underground projects and rock mass rating(RMR) is one of the most commonly applied classification systems in numerous civil and mining projects. The type of rock mass consisting of an interbedding of strong and weak layers poses difficulties and uncertainties for determining the RMR. For this, the present paper uses the concept of rock bolt supporting factor(RSF) for modification of RMR system to be used in such rock mass types. The proposed method also demonstrates the importance of rock bolting practice in such rock masses. The geological parameters of the Shemshak Formation of the Alborz Tunnel in Iran are used as case examples for development of the theoretical approach.
文摘The Firefly Algorithm(FA)is a highly efficient population-based optimization technique developed by mimicking the flashing behavior of fireflies when mating.This article proposes a method based on Differential Evolution(DE)/current-to-best/1 for enhancing the FA's movement process.The proposed modification increases the global search ability and the convergence rates while maintaining a balance between exploration and exploitation by deploying the global best solution.However,employing the best solution can lead to premature algorithm convergence,but this study handles this issue using a loop adjacent to the algorithm's main loop.Additionally,the suggested algorithm’s sensitivity to the alpha parameter is reduced compared to the original FA.The GbFA surpasses both the original and five-version of enhanced FAs in finding the optimal solution to 30 CEC2014 real parameter benchmark problems with all selected alpha values.Additionally,the CEC 2017 benchmark functions and the eight engineering optimization challenges are also utilized to evaluate GbFA’s efficacy and robustness on real-world problems against several enhanced algorithms.In all cases,GbFA provides the optimal result compared to other methods.Note that the source code of the GbFA algorithm is publicly available at https://www.optim-app.com/projects/gbfa.
文摘Tomato is one of the extensively consumed vegetable crops worldwide. The regular consumption of tomato decreases the incidence of chronic degenerative diseases such as certain types of cancer and cardiovascular diseases. The objective of this study was to find an appropriate method that not only reduces tomatoes decay, but also maintains its post-harvest quality. A factorial experiment based on randomized complete block design with three replications was conducted to evaluate effects of ultraviolet（UV）-C and CaCl_2 applications on tomato during storage. The traits studied included ethylene, polygalacturonase（PG） activity, pectin methyl esterase（PME） activity, firmness, total phenol content, and fungal-induced decay were measured weekly during 35 days of storage. Both UV-C and CaCl_2 treatments had positive effects on tomato quality as compared to control treatment. The 3 and 4.5 k J m^（-2） levels of UV-C and 2% CaCl_2 had positive effects on quality characteristics, respectivly. Fruits treated by UV-C and CaCl_2 had higher phenol and firmness, and less PME activity, PG activity, ethylene production, and decay than the control fruits. In conclusion, increasing in storage duration significantly affected the fruits quality by increasing in ethylene, PME activity, PG activity, decay and decreasing the phenol content and firmness. But UV-C and CaCl_2 led to significant decrease in this adverse impact relative to control treatment.
文摘BACKGROUND： Analgesic and wound-healing effects of cinnamon, a widely used spice, have been shown in laboratory rats. However, we found no human studies in this area. OBJECTIVE： The aim of this study was to assess the effect of cinnamon on perineal pain and healing of episiotomy incision. DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS： In this double-blind, randomized, placebo-controlled trial, 144 postpartum women were allocated into two groups, using stratified block randomization, 1 h after completion of episiotomy repair. They received cinnamon or placebo ointment, 2 mL every 12 h for 10 d. MAIN OUTCOME MEASURES： Perineal pain and wound healing were assessed using visual analogue scale （0-10）and Redness, Edema, Ecchymosis, Discharge, Approximation scale （0-15）, respectively. General linear model was used to compare the groups on the outcomes adjusted for baseline values and stratified factors. RESULTS： Follow-up rate was 100% up to the 8 h time point in both groups, and 86% （62 of 72） in the cinnamon group and 85% （61 of 72） in the placebo group at day 10-11 after delivery. Pain score in the cinnamon group was significantly lower than that in the placebo group at （4±1） h （adjusted difference： -0.6, 95% confidence interval： -1.0 to -0.2） and （8＋1） h （-0.9, -1.4 to -0.3） after intervention, and on the 10-11th day after delivery （-1.4, -2.0 to -0.7）. Also the cinnamon group showed significantly more improvement than the control group in healing score at （8±1） h （-0.2, -0.4 to -0.04） and the 10-11th day after delivery （-1.6, -2.0 to -1.1）. CONCLUSION： Cinnamon can be used for reducing perineal pain and improving healing of episiotomy incision.
