1,705 research outputs found

    Comparison of ferment sugars, produce hemolysis and measuring growth in methicillin-resistant and methicillin-sensitive Staphylococcus aureus isolates from inpatients and healthcare workers in Gorgan Hospitals, North of Iran

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    The mec A gene in Staphylococcus aureus leads to production of new penicillin-binding protein called PBP2a.This change may follow some changes in other phenotypes. The aim of this study was the comparison of Ferment Sugars, Produce Hemolysis and Measuring Growth in MRSA and MSSA isolates. 188 Staphylococcus aureus isolates separated from inpatients and healthcare workers (healthy carriers)were studied.Bacterialcultures in blood agar environment at 37°C during 24h and at 4°C during other 24h were applied for studying hemolysis. Sugar fermentation carried out in phenol red Broth medium, containing glucose, galactose, arabinose, fructose, xylose, ramnose, mannose, sucrose, trehalose, raffinose or maltose. For determining bacterial growth,bacterial concentration of 103was taken each hour during 12 cultured in MHAand colonies were counted after 24h.The mean amount of hemolysis diameter in MRSA isolates was rather more than that of MSSA isolates. The difference between MRSA and MSSA isolates were significant as to fermenting ramnose, trehalose, galactose and xylose. The mean rate of growth in MRSAwere significantly different from that of MSSAisolates (p<0.05).Resistance to methicillin in Staphylococcus aureus isolates accompanies the increase of ability to ferment sugars. This phenomenon may be one of reasons for increased pathogenicity of MRSA isolates; So results shows the logarithmic phase is longer in MRSA isolates, This may implicate that PBP2a production in methicillin-resistant isolates follows slowing down nutrients entrance into the bacterium that in turn may causes slow growth

    Sustainability of the Dujiangyan irrigation system for over 2000 years–A numerical investigation of the water and sediment dynamic diversions

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    The Dujiangyan Irrigation System (DIS), located in the western portion of the Chengdu Plain at the transitional junction between the Qinghai-Tibet Plateau and Sichuan Basin, has been in operation for about 2300 years. The system automatically uses natural topographical and hydrological features and provides automatic water diversion, sediment drainage and intake flow discharge control, thus preventing disastrous events in the region in a ‘natural’ way. Using a numerical modeling approach, this study aims to investigate the reasons behind this natural behavior of the system and provide a better understanding of the complex mechanisms which have caused the sustainability of the DIS for over two millennia. For this purpose, a two-phase flow model based on the Shallow Water Equations (SWEs) is developed to simulate the fluid and sediment motions in the DIS. A coupled explicit-implicit technique based on the Finite Element Method is applied for the fluid flow and a Sediment Mass (SM) model in the framework of the Lagrangian particle method is proposed to simulate the sediment motion under different flow discharge conditions. The results show how different components of the DIS make full use of the hydrodynamic and topographical characteristics of the river to effectively discharge sediment and excess flood to the downstream and create an environmentally sustainable irrigation system

    SPH based numerical treatment of the interfacial interaction of flow with porous media

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    In this paper, the macroscopic equations of mass and momentum are developed and discretised based on the Smoothed Particle Hydrodynamics (SPH) formulation for the interaction at an interface of flow with porous media. The theoretical background of flow through porous media is investigated in order to highlight the key constraints which should be satisfied, particularly at the interface between the porous media flow and the overlying free flow. The study aims to investigate the derivation of the porous flow equations, computation of the porosity, and treatment of the interfacial boundary layer. It addresses weak assumptions that are commonly adopted for interfacial flow simulation in particle‐based methods. As support to the theoretical analysis, a 2D weakly compressible SPH (WCSPH) model is developed based on the proposed interfacial treatment. The equations in this model are written in terms of the intrinsic averages and in the Lagrangian form. The effect of particle volume change due to the spatial change of porosity is taken into account and the extra stress terms in the momentum equation are approximated by using Ergun's equation and the Sub‐Particle Scale (SPS) model to represent the drag and turbulence effects, respectively. Four benchmark test cases covering a range of flow scenarios are simulated to examine the influence of the porous boundary on the internal, interface and external flow. The capacity of the modified SPH model to predict velocity distributions and water surface behaviour is fully examined with a focus on the flow conditions at the interfacial boundary between the overlying free flow and the underlying porous media

    Induced Nucleon Polarization and Meson-Exchange Currents in (e,e'p) Reactions

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    Nucleon recoil polarization observables in (e,ep)(e,e'\vec{p}) reactions are investigated using a semi-relativistic distorted-wave model which includes one- and two-body currents with relativistic corrections. Results for the induced polarization asymmetry are shown for closed-shell nuclei and a comparison with available experimental data for 12^{12}C is provided. A careful analysis of meson exchange currents shows that they may affect significantly the induced polarization for high missing momentum.Comment: 7 pages, 9 figures. Revised version with small changes, new curve in Fig. 3. To be published in PR

    Influence of roasting, gamma ray irradiation and microwaving on ruminal dry matter and crude protein digestion of cottonseed

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    The aim of the current study was to compare the effect of different physical processing methods including roasting at 140 C for 15 (R15) or 30 minutes (R30), gamma ray irradiation (c-irradiation) at doses of 15 (c15), 30 (c30) and 45 (c45) kGy, and microwaving at 800 W for 2 (MW2), 4 (MW4) and 6 minutes (MW6) of whole cottonseed (WCS) on ruminal degradation. In vitro crude protein (CP) digestibility and gossypol contents were compared as well. In situ experiment was conducted on three permanent rumen-fistulated bulls. Gossypol content was decreased among treatments (p<0.05). The lowest degradation rate of protein in rumen was obtained for c45 treatment. The rate of degradation of the potentially degradation fraction was decreased for both dry matter (DM) (p¼0.002) and CP (p¼0.006) with different treatments. The lowest values for effective degradation in all passage rates were obtained with c45. Both microwaving and c irradiation showed difference for CP effective degradability parameter. The greatest value of in vitro CP digestibility (p<0.05) was observed for a dose of 45 kGy gamma-irradiated cottonseed compared to untreated WCS. Based on the results, c ray irradiation with 45 kGy was the most effective processing method in both reducing the gossypol content and escaping the protein through rumen for WCS in ruminant nutrition

    The effects of Momordica charantia on liver function and histological structure

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    Introduction: The application of herbal plants because of their lower side-effects has been increasing in recent years. Objectives: we aimed to study the effects of hydro-alcoholic extract of Momordica charantia (bitter melon) on liver function and tissue structure in mice. Materials and Methods: This study was conducted on 70 male mice which were randomly designated into 7 groups of 10 and were injected with single doses of 0, 100, 500, 1000, 2000 and 4000 mg/kg and multiple daily dose of 500 mg/kg for 7 days, intraperitoneally. Finally, liver tissues were taken out for histological examinations. Serum samples were assayed for liver enzymes activities of alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase. Also the antioxidant activity of blood and bitter melon were measured. Subsequently, data were analyzed by analysis of variance (ANOVA) and Bonferroni tests using Stata software. Results: The results of the present study showed that a single dose of Momordica charantia fruit extract at doses up to 4000 mg/kg extract does not significant adverse effects on the liver enzymes and tissue structure. Conclusion: Using this drug for short time and low dose has not toxicity effects on liver enzymes activity and tissue structure, hence, it is safe in this range of doses

    Effect of feeding rainbow trout larvae (Oncorhynchus mykiss) with Artemia nauplii enriched with vegetable oils on resistance against O2, salinity and temperature stresses

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    Chronic stresses can influence the behavioral and physiological activities of animals and can lead to reduction of resistance against disease and decrease in growth rate and production.Artemianauplii enriched with essential nutrients particularly fatty acids have been used to promote growth, survival and resistance of different species of aquatic animals to various environmental stresses as well as infectious diseases. In this study we investigated the resistance to environmental stress (temperature, salinity and hypoxi) in larvae of rainbow trout fed Artemianauplii enriched with vegetable oils. The experiment was carried out in 6 triplicate treatments for a period of 10 days. The feeding treatments included: 1) commercial starter feed for trout (Control) 2) Artemianauplii enriched with fish oil, 3) Artemianauplii enriched with sunflower oil, 4) Artemianauplii enriched with canola oil, 5) Artemianauplii enriched with soybean oil and 6) newly hatched nauplli of Artemia. The results showed significant differences in tolerance of fish larvae to high temperature (20 and 25°C), hypoxia stress (5 ppm) and salinity stress (10, 15 and 20 mg.l-1) among different groups. Highest survival to all experimental stresses (except in one case) was observed in larvae fed Artemianauplii enriched with canola oil compared to those fed control diet ( p<0.05), but in most cases not significant with larvae fed Artemianauplii enriched with fish oil

    First report of a genus and species of the family Dinychidae (Acari: Mesostigmata: Uropodoidea) from Iran

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    در بررسی فون کنه‌های میان‌استیگمای خاکزی در استان گلستان که در تابستان 1389 انجام شد، یک گونه از کنه‌های جنس Dinychus Kramer, 1882 به نام Dinychus woelkei Hirschmann & Zirngiebl-Nicol, 1969 از جنگل قرن‌آباد از داخل کنده پوسیده درختی جمع‌آوری و شناسایی شد. این نخستین گزارش این جنس و گونه از ایران است
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