49 research outputs found

    Electroosmotic Pressure-Driven Flow through a Slit Micro-Channel with Electric and Magnetic Transverse Field

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    In the present study, flow through two-dimensional microchannel under an axial electric field, transverse electric and magnetic fields and with axial pressure gradient has been investigated numerically. Continuity and momentum equations were solved steadily with respect to the non-slip condition by using discrete finite volume method and a numerical code. The results show that in the presence of the axial electric field, applying transverse magnetic field reduces flow velocity. However, when the transverse electric field and axial electric field exist together, applying the transverse magnetic field increases the flow rate to a certain extent and then reduces the flow rate. Hartmann number like this amount of magnetic field is known as critical Hartmann number. Therefore, with the presence of transverse and axial electric fields and transverse magnetic field, the highest possible flow rate is for critical Hartmann number. It was also found that by increasing the pressure gradient within the microchannel, the critical Hartmann number decreases. Moreover, by increasing the transverse electric field, the sensitivity of critical Hartmann number to the pressure gradient decreases and its value tends to a specific number (about 1.5)

    Evaluation of Factors Affecting Water Erosion along Skid Trails (Case study; Shafarood Forest, Northern Iran)

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    Water erosion causes severe soil damage in northern forests of Iran which is associated with different rut depths in skid trails. The aim of this study was to assess rutting and soil displacement on skid trails to mitigate water erosion. Therefore the research was carried out in eight parcels of district No 3 of Shafarood Forest in the North of Iran. In order to evaluate the amount of erosion in skid trails, 30 lateral profiles in three slope classes (0-15, 15-25 and >25%) were randomly chosen from 10 skid trails. The amount of soil displaced and ruts were measured using lateral profile of skid trail. Then the effective factors on soil disturbances such as longitudinal slope, soil texture, crown canopy and forest floor cover were separately measured in the studied plots. The results of regression analysis showed that there were significant differences between amount of soil erosion and longitudinal slope, soil texture, crown canopy and forest floor cover. The results from Pearson test showed that there was significant correlation between amount of soil erosion and longitudinal slope of skid trails, soil texture and forest floor cover (α= 0.01 and α= 0.05), but there was no significant correlation between amount of soil erosion and crown canopy. The results of this research showed that by increasing longitudinal slope of skid trail, displaced soil volume and rutting depth increased. The sample plots in longitudinal slope class of >25% and average displaced soil volume of 5.3 m3 had maximum disturbance. Mean comparison test also showed that there were no significant differences in the displaced soil volume in the two longitudinal slope classes (0-15 and 15-25%), but with an increase in longitudinal slope (more than 25%), the average displaced soil volume increased

    Echocardiographic findings and joint hypermobility: Patients with mitral valve prolapse vs. healthy controls

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    Background: Mitral valve prolapse is a relatively common valvular abnormality in most communities and joint hypermobility (JHM) is also seen in many healthy people as well as in certain clinical disorders, such as Marfan syndrome. The present study was designed to investigate the association between joint hypermobility and mitral valve prolapse (MVP) in an Iranian population sample. Methods: Fifty-seven patients with nonrheumatic and isolated mitral anterior leaflet prolapse (24 men and 33 women, mean age 23.5 +/-2.3) and 51 healthy subjects (20 men and 31 women, mean age 22.9+/-2.3) were studied. The presence of JHM was evaluated according to the Carter-Wilkinson & Beighton criteria. Echocardiographic examination was performed in all subjects and the correlation between the echocardiographic features of the mitral valve and the hypermobility score were investigated. Results: The frequency of JHM in patients with MVP was found to be significantly higher than that of controls (26.3 vs. 7.8), with mean JHM scores of 3.1+/-2.2 and 1.9+/-1.7, respectively. The patients in the MVP group had significantly increased the anterior mitral leaflet thickness (AMLT, 3.4+/-0.4 mm vs. 3.0+/-0.3 mm; p<0.0005) and maximal leaflet displacement (MLD, 2.4+/-0.3 mm vs. 1.5+/-0.2 mm; p<0.0005) compared to the controls. Conclusions: We detect a statistically significant relationship between isolated MVP and joint hypermobility as well as between the severity of JHM and echocardiographic features of the mitral leaflets. These results suggest a common etiology for MVP and JHM, which should be investigated in future well-conducted studies. © 2008, Tehran University of Medical Sciences. All rights reserved

    Laboratory culture of Artemia urmiana using Isfahan province drainages

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    Esfahan province is located in center of Iran at 51° 31 ' E and 33° 29 ' N with area near 15745 Km^2 that consists of 9 percent of the country. According to cilianinof scale it enjoys an arid climate. The mean annual precipitation is equal to 135 mm. Average annual temperature is 16.8°C and mean annual evaporation is 2435 mm in Gavkhoni catchment's area. It has several drainages channels such as north and south rodashtain, segzi drainage, main drainage of water supply organization channel, fender drainage, main drainage, Marchi class II drainage and other drainage channels. Their waterdebi volume is equal to 900l/s. Also, their water can not use for agriculture, drinking and industrial purposes due to high salinity. This study was concluded to optimal use of these water resources aiming at possibilities of culture and propagation of Artemia from Urmia Lake. In this study, physicochemical factors analysis of water, the climate profile, and fauna and flora of the region were identified and determined. In rodashtain region drainages, 2 sites in varzaneh and Sian drainages from gavkhoni wetland limitation were chosen and studied. Water samples in 50-100 liter volumes were taken from their run off waters with 3 replicates. Artemia cysts were hatched under standard laboratory condition according to Lavens and Sorgeloos, 1996). Cyst hatching was carried out in 1.5 liter conical zooks 2 g of Artemia cyst per one liter of drainage water was added to each treatment together with one evidence. Hatching percentage and hatching efficiency were determined. Hatching percentage and hatching efficiency after 76 hours were equal to 55±10 percent and 92000±1200 Nauplii/g cyst in the evidence with tap water and 27±5 % and 31000±1000 in varzaneh drainage water and 13±5 % and 11000±1000 in Sian drainage waters, respectively. Then, all hatched nauplii were cultured in 3 aquarium containing each 100 liters together with one evidence with 3 replicates containing 50 liters in each aquarium in laboratory. Nauplii were fed using a suspension with rice bran, Dunaliella and Naunochlorepsis with density of 2 ×10^ 6 cell/ml. The growth of Artemia Nauplii was slow at the first week of culture and then continued with suitable norm and lower mortality until maturation. The mean size of Nauplii length reached to 9 mm after 2 weeks. Their fecundity was 50 cyst per female. The drainage waters of studied sites can be used as a suitable water source at semi- industrial Artemia production pilot in the region

    Hydrogen and fluorine migration in photo-double-ionization of 1,1-difluoroethylene (1,1-C2H2F2) near and above threshold

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    We have studied the nondissociative and dissociative photo-double-ionization of 1,1-difluoroethylene using single photons of energies ranging from 40 to 70 eV. Applying a coincident electron-ion three-dimensional momentum imaging technique, kinematically complete measurements have been achieved. We present the branching ratios of the six reaction channels identified in the experiment. Electron-ion energy maps and relative electron emission angles are used to distinguish between direct and indirect photo-double-ionization mechanisms at a few different photon energies. The influence of selection and propensity rules is discussed. Threshold energies of double ionization are extracted from the sum of the kinetic energies of the electrons, which hint to the involvement of different manifolds of states. The dissociative ionization channels with two ionic fragments are explored in detail by measuring the kinetic energy release of the fragment ions, sum of the kinetic energies, as well as the energy sharing of the two emitted electrons. We investigate the migration of hydrogen and fluorine atoms and compare the experimental results to the photo-double-ionization of centrosymmetric linear and planar hydrocarbons (C[subscript 2]H[subscript 2] and C[subscript 2]H[subscript 4]) whenever possible

    Effect of fish oil on circulating asymmetric dimethylarginine and adiponectin in overweight or obese patients with atrial fibrillation

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    Obesity and adipose-derived peptides might be involved in the pathogenesis of atrial fibrillation (AF). Adiponectin plays a major role in the modulation of several metabolic pathways, and asymmetric dimethylarginine (ADMA) has been suggested to be predictive of AF and associated adverse events. The aim of this study was to investigate the effect of fish oil supplementation on circulating adiponectin and ADMA in overweight or obese patients with persistent AF. In this randomized, double-blind, placebo-controlled trial, 80 overweight or obese (body mass index (BMI) � 25 kg/m2) patients with persistent AF were randomly assigned to two groups to receive either 2 g/day fish oil or placebo, for 8 weeks. Serum levels of adiponectin and ADMA, and anthropometric indexes were measured. This study showed that serum adiponectin concentrations increased significantly following fish oil supplementation compared with the placebo group (13.15 ± 7.33 vs. 11.88 ± 6.94 µg/ml; p =.026). A significant reduction was also observed in serum ADMA levels in the fish oil compared with the placebo group following the intervention (0.6 ± 0.13 vs. 0.72 ± 0.15 µmol/L; p =.001). The changes in serum adiponectin and ADMA concentrations remained significant after adjustments for baseline values, age, sex, and changes of BMI and waist circumference (p =.011 and p =.001, respectively). In conclusion, 8 weeks supplementation with fish oil increased serum adiponectin and decreased ADMA concentrations in overweight or obese patients with persistent AF. As adiponectin and ADMA are suggested to be involved in many pathways associated with AF, the current findings might be promising in the clinical management of this disease, an issue that needs further investigations. © 2020 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc

    Unambiguous observation of F-atom core-hole localization in CF4 through body-frame photoelectron angular distributions

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    Citation: McCurdy, C. W., Rescigno, T. N., Trevisan, C. S., Lucchese, R. R., Gaire, B., Menssen, A., . . . Weber, T. (2017). Unambiguous observation of F-atom core-hole localization in CF4 through body-frame photoelectron angular distributions. Physical Review A, 95(1). doi:10.1103/PhysRevA.95.011401A dramatic symmetry breaking in K-shell photoionization of the CF4 molecule in which a core-hole vacancy is created in one of four equivalent fluorine atoms is displayed in the molecular frame angular distribution of the photoelectrons. Observing the photoejected electron in coincidence with an F+ atomic ion after Auger decay is shown to select the dissociation path where the core hole was localized almost exclusively on that atom. A combination of measurements and ab initio calculations of the photoelectron angular distribution in the frame of the recoiling CF3+ and F+ atoms elucidates the underlying physics that derives from the Ne-like valence structure of the F(1s-1) core-excited atom. © 2017 American Physical Society
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