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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Iranian Journal of Oil and Gas Science and Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: ultrasonic,waste water,lead,nZVI
- چکیده:
- چکیده انگلیسی: This research reported a new method of removal of Pb+2from water by using a nano zero valent iron (nZVI) assisted ultrasonic wave. At first, nZVI was synthesized by an ultrasound assisted method. Particles morphology and surface composition were characterized by FESEM, XRD, and EDX. The XRD patterns showed that the crystallinity of the nZVI prepared using ultrasonic conditions was higher than the conventional method. According to the EDX pattern, 67% of particle composition was nZVI. The synthesized nanoparticles were then utilized as a Fenton-like catalyst for the removal of Pb+2from water using an ultrasound assisted method. In the present study, ultrasound power, temperature effects, nZVI, and reaction time were optimized. From the studies, it has been observed that removal does not increase indefinitely with an increase in ultrasound power, but it instead reaches an optimum value and decreases with a further increase in the ultrasound power. The removal of Pb+2increased with increasing temperature, nZVI, and H2O2 concentration. The result indicated that the efficiency of hydrocarbon removal by this novel method was 97.87%.
- انتشار مقاله: 30-07-1393
- نویسندگان: Mirroozbeh Jamei,Mohammad Khosravi Nikou
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Gastrointestinal hemorrhage,renal cell carcinoma,Duodenal ulcer,Pancreaticoduodenectomy
- چکیده:
- چکیده انگلیسی: Renal cell carcinoma comprises about 2% of adult tumors. The overall 10-year survival rate of patients with RCC after nephrectomy is about 18-27%. The incidence of metastasis of initial RCC is about 24-28%, but this rate after nephrectomy is as high as 51%. The most common site of recurrence is the lung, however liver and bone metastases are common.There are many reported cases with late metastasis, however isolated late metastasis in the gastrointestinal tract especially duodenum is very rare.Herein we report our experience with a case of gastrointestinal bleeding secondary to metastatic renal cell carcinoma to duodenum, 16 years after nephrectomy.To the best of our knowledge, about 30 of such cases have been reported in the English literature. Many of the previous cases have been part of disseminated disease and isolated duodenal metastasis is very rare. The longest reported duration between nephrectomy for renal cell carcinoma and duodenal metastasis has been 13 years, thus it seems our case to be also unique because of very late duodenal metastasis.
- انتشار مقاله: 11-12-1393
- نویسندگان: Bita Geramizadeh,AmirAhmad Mostaghni,Zeinab Ranjbar,Farid Moradian,Mina Heidari,Mohammad Bagher Khosravi,Seyed Ali Malekhosseini
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Acidosis,Liver Transplantation,Sodium bicarbonate,Crystalloid solution
- چکیده:
- چکیده انگلیسی: Background: Severe metabolic acidosis occurs during orthotopic liver transplantation (OLT) particularly during the anhepatic phase. Although NaHCO3 is considered as the current standard therapy, there are numerous adverse effects. The aim of this study was to determine whether the restricted use of normal saline during anesthesia could reduce the need for NaHCO3.Methods: In this study we enrolled 75 patients with end-stage liver disease who underwent OLT from February 2010 until September 2010 at the Shiraz Organ Transplantation Center. Fluid management of two different transplant anesthetics were compared. The effect of restricted normal saline fluid was compared with non-restricted normal saline fluid on hemodynamic and acid-base parameters at three times during OLT: after the skin incision (T1), 15 min before reperfusion (T2), and 5 min after reperfusion (T3). Results: There were no significant differences in demographic characteristics of the donors and recipients (P>0.05). In the restricted normal saline group there was significantly lower central venous pressure (CVP) than in the non-restricted normal saline group (P=0.002). No significant differences were noted in the other hemodynamic parameters between the two groups (P>0.05). In the non-restricted normal saline group arterial blood pH (P=0.01) and HCO3 (P=0.0001) were significantly less than the restricted normal saline group. The NaHCO3 requirement before reperfusion was significantly more than with the restricted normal saline group (P=0.001).Conclusion: Restricted normal saline administration during OLT reduced the severity of metabolic acidosis and the need for NaHCO3 during the anhepatic phase.Trial Registration Number: IRCT2013110711662N5
- انتشار مقاله: 12-05-1392
- نویسندگان: Mohammad Ali Sahmeddini,Farahzad Janatmakan,Mohammad Bagher Khosravi,Sina Ghaffaripour,Mohammad Hossein Eghbal,Sakine Shokrizadeh
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Type 2 diabetes mellitus,Renovascular hypertension,Cardiac functions
- چکیده:
- چکیده انگلیسی: Background: The cardiac effects simultaneously occurring during experimental hypertension and diabetes have rarely been investigated. This study aimed at examining the effects of short-term renovascular hypertension and type 2 diabetes on cardiac functions. Methods: Five groups (7 each) of male Sprague-Dawley rats, including a control group, a diabetes (induced by Streptozocin and Nicotinamide) group, a renovascular hypertensive (induced by placing Plexiglas clips on the left renal arteries) group, a sham group, and a simultaneously hypertensive-diabetic group, were used. The animals’ hearts were used for isolated heart studies, and the indices of cardiac functions and coronary effluent creatine kinase MB were measured. The results were analyzed using One-way Analysis of Variance, followed by the Duncan Multiple Range test.Results: The diabetic group had a significantly lower rate of rise (-29.5%) and decrease (-36.18%) in ventricular pressure, left ventricular developed pressure (-28.8%), and rate pressure product (-35%), and significantly higher creatine kinase MB (+166%) and infarct size (+36.2%) than those of the control group. The hypertensive group had a significantly higher rate of rise (+12.17%) and decrease (+16.2%) in ventricular pressure, left ventricular developed pressure (+16%), and rate pressure product (+24%), and significantly lower creatine kinase MB (-30%) and infarct size (-27%) than those of the sham group. Simultaneously, the diabetic and hypertensive rats had a significantly higher rate of rise (+32%) and decrease (+30.2%) in ventricular pressure, left ventricular developed pressure (+17.2%), and rate pressure product (+22.2%), and significantly lower creatine kinase MB (-24%) and infarct size (-16.2%) than those of the diabetic group.Conclusion: The findings indicated that the simultaneity of hypertension with type 2 diabetes attenuated diabetes-induced cardiac impairment.
- انتشار مقاله: 01-10-1392
- نویسندگان: Ali Akbar Nekooeian,Azadeh Khalili,Mohammad Bagher Khosravi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Sciences
- نوع مقاله: Journal Article
- کلمات کلیدی: Liver Transplantation,Hyperkalemia,orthotopic
- چکیده:
- چکیده انگلیسی: A serious hazard to patients during orthotopic liver transplantation is hyperkalemia. Although the most frequent and hazardous hyperkalemia occurs immediately after reperfusion of the newly transplanted liver, morbid hyperkalemia could happen in the other phases during orthotopic liver transplantation. However, pre-anhepatic hyperkalemia during orthotopic liver transplantation is rare. This report describes one such patient, who without transfusion, developed severe hyperkalemia during pre-anhepatic phase. The variations in serum potassium concentration of the present case indicate that it is necessary to take care of the changes of serum potassium concentration not only during reperfusion but also during the other phases of the liver transplantation.
- انتشار مقاله: 17-09-1392
- نویسندگان: Mohammad Ali Sahmeddini,Mohammad Bagher Khosravi
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Mining and Geo-Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Active earth pressure,rigid retaining wall,rotation mode,translation mode
- چکیده:
- چکیده انگلیسی: The design of retaining walls depends on the magnitude of active pressure exerted from the backfill. Therefore, estimating the scale of this pressure is a fundamental factor in the design. In this study, to assess the active earth pressure, a rigid retaining wall was built capable of translating and/or rotating with adjustable speed. Further, several physical tests were conducted on a laboratory scale under the influence of uniform surcharge. In order to evaluate the behavior of the soil and the failure wedge, circular flat pressure cells and particle image velocimetry method were used. The results indicated that in the translation and translation-rotational modes, the distribution of lateral active pressure along the wall height was non-linear while it was relatively linear under rotation around the base. By increasing the amount of surcharge, the effect of the arching phenomenon at the lower portion of the wall was more evident. This led to a negligible magnitude of pressure at the base of the wall. In addition, it was observed that during the active motion of the wall, the distinction between the stationary region and the failure zone was a function of the mode of wall motion.
- انتشار مقاله: 23-02-1398
- نویسندگان: Negar Salehi Alamdari,Mohammad Hossein Khosravi,Hooshang Katebi
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Mining and Geo-Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Active earth pressure,rigid retaining wall,rotation mode,translation mode
- چکیده:
- چکیده انگلیسی: The design of retaining walls depends on the magnitude of active pressure exerted from the backfill. Therefore, estimating the scale of this pressure is a fundamental factor in the design. In this study, to assess the active earth pressure, a rigid retaining wall was built capable of translating and/or rotating with adjustable speed. Further, several physical tests were conducted on a laboratory scale under the influence of uniform surcharge. In order to evaluate the behavior of the soil and the failure wedge, circular flat pressure cells and particle image velocimetry method were used. The results indicated that in the translation and translation-rotational modes, the distribution of lateral active pressure along the wall height was non-linear while it was relatively linear under rotation around the base. By increasing the amount of surcharge, the effect of the arching phenomenon at the lower portion of the wall was more evident. This led to a negligible magnitude of pressure at the base of the wall. In addition, it was observed that during the active motion of the wall, the distinction between the stationary region and the failure zone was a function of the mode of wall motion.
- انتشار مقاله: 23-02-1398
- نویسندگان: Negar Salehi Alamdari,Mohammad Hossein Khosravi,Hooshang Katebi
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Mining and Geo-Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Retaining walls,Lateral earth pressure,Arching effect, Soil arching
- چکیده:
- چکیده انگلیسی: Granular materials have a tendency to exhibit an arching effect by which the load is transferred from yielding parts to adjacent stationary parts. Retaining walls are among those structures that the soil arching plays an important role in the distribution of earth pressures. This paper briefly reviews the development of soil arching theory and its application to different geotechnical projects. Various arching-based theoretical formulations for estimation of lateral active earth pressure on the rigid retaining walls were reviewed and their validity was examined through comparisons with the filed data. It was concluded that, in spite of the conventional thought that the distribution of lateral earth pressure on the walls is linear; it is non-linear due to soil arching. Moreover, the maximum lateral stress does not appear at the toe of the wall; but at some heights, leading to a shift of the point of application of thrust from 33% to approximately 45% of the wall height measured from the bottom of the wall.
- انتشار مقاله: 27-05-1397
- نویسندگان: Mohammad Hossein Khosravi,Mojtaba Bahaaddini,Ali Reza Kargar,Thirapong Pipatpongsa
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Mining and Geo-Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Numerical analysis,Retaining walls,Lateral earth pressure,PFC2D
- چکیده:
- چکیده انگلیسی: In this paper, the problem of a retaining wall under active translation mode is investigated numerically. To this end, a series of numerical models is conducted using the discrete element code, PFC2D. The backfill soil is simulated by an assembly of separate cohesionless circular particles. Backfill soil was prepared by pouring soil particles from a specific height under gravity force and giving them enough time for appropriate settlement. Different heights of retaining walls are simulated and the lateral earth pressure on the wall is observed under both at-rest and active conditions. Numerical results compared with predictions from some analytical methods and measurements from physical models. The active state of earth pressure is defined as the earth pressure distribution corresponding to the values of wall displacement where the failure zone in the backfill is fully developed. The numerical results showed that the fully active state of earth pressure occurred at a wall displacement corresponding to the strains required for reaching the critical state in biaxial compressive tests.
- انتشار مقاله: 18-02-1396
- نویسندگان: Mohammad Hossein Khosravi,Farzaneh Hamedi Azad,Mojtaba Bahaaddini,Thirapong Pipatpongsa
- مشاهده
- جایگاه : پژوهشی
- مجله: International Journal of Mining and Geo-Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Numerical modeling,Arching Effect,Undercut Slopes,Counterweight Balance
- چکیده:
- چکیده انگلیسی: One of the important parameters in undercut slopes design is the determination of the maximum stable undercut span. The maximum stable undercut span is a function of slope geometry, the strength parameters of the slope material, condition of discontinuities, underground water condition, etc. However, the desired production capacity and therefore the size of excavating equipment will sometimes ask for a wider undercut span. The influence of arching phenomenon in geo-material on the stability of undercut slopes is investigated earlier. It is believed that due to arching effect, some load transfer from the undercut area into stationary remaining side toes leads to a more stable slope. However, the transferred load may result in ploughing failure of side toes. One technique for preventing the ploughing failure is the use of counterweight balance on side toes. In this study, the influence of counterweight size on the stability of the undercut slopes was investigated through a series of numerical model tests using FLAC3D software. It was concluded that there is a meaningful relationship between the counterweight balance size and the maximum stable undercut span where increasing a counterweight size results in a wider stable span. Finally, the numerical results were compared with pre-conducted physical modeling test and a nonlinear relationship was proposed between the counterweight size and the maximum stable undercut span.
- انتشار مقاله: 28-07-1395
- نویسندگان: Mohammad Hossein Khosravi,Hassan Sarfaraz,Mahmoud Esmailvandi,Thirapong Pipatpongsa
- مشاهده