Circuit - based transient model of grounding electrode with consideration of soil ionization and current rate of rise factors

The behaviour of a grounding electrode can be predicted by using either the electrical circuit model or electromagnetic computation. Despite its advantages over the latter, the grounding circuit model fails to accurately predict the behaviour under transient conditions due to the absence of two key factors, namely the soil ionization, and the current rate–of–rise. A new equivalent circuit model of a grounding electrode with dynamic circuit elements (Rd, Cd, and Ld) was developed to consider both soil ionization and current rate–of–rise factors. A generalized formula was derived to calculate the dynamic inductance, Ld, for all standard current wave shapes such as Conseil International des Grands Réseaux Électriques (CIGRE), double–exponential, and IEC 62305–1 (International Electrotechnical Commission). The computed inductance, Ld, dynamically changes with the change in the lightning current parameters, thus improving its accuracy for all current rate–of–rise conditions. The consideration for the soil ionization effect on grounding electrode resistance, Rd, and soil capacitance, Cd, within the equivalent circuit model was achieved by modelling the soil with a network of two layer capacitors (TLC) in which soil particles and air voids are the TLC components. Differential equations were derived to incorporate the soil ionization phenomenon inside the TLC network. The voltage response of the new equivalent circuit model and the dynamic circuit elements were determined by using the above–suggested methods, is more accurate than that of the conventionally determined grounding circuit models. The overall differences between the equivalent circuit model and several experiments are 3.3% for the electrode resistance and 2.8% for the electrode peak voltage. The new equivalent circuit model helps to optimize the overall grounding electrode design, and to provide a better fast transient protection and insulation coordination

The antinociceptive effect of hydro-alcoholic extract of leave Mentha pulegium in formalin test in male rat

Background and aim: Drug researchers believe that pain relief medicines, because of their side effects and in some cases because of their inabilities are not useful. Therefore, it is necessary to do more research to find out new antinociceptive drugs. In the present study, antinociceptive effect of hydro-alcoholic extract of Mentha pulegium leave has been evaluated in male rats. Methods: In this experimental study, 40 adult male wistar rats, in the weight range of 220- 230 g were used. Antinociceptive response was evaluated by formalin test in five groups of 8 animals. Three experimental groups received 3 different doses of hydro alcoholic extract from the leaves of Mentha pulegium (400, 800, 1600 mg/kg, respectively). Sham group received distilled water and formalin only and the control group received no drugs. The extracts were injected intraperitoneally (i.p.), 15 minutes before the formalin test. Minutes 0-5 and 15-60 were designated as the acute and chronic phase of pain, respectively. After recording behavioral responses, the average pain scores in experimental groups and control group were statistically evaluated using t-test and Tukey’s test. Results: A significant difference was seen in mean pain scores between 3 experimental groups in the acute stage of formalin test. In the chronic stage, the only significant difference was seen between the experimental group which had been received 1600 mg/kg Mentha pulegium and two other groups (sham and control group) (P<0.05). Conclusion: According to the results of this research, the hydro-alcoholic extract of the leaves of Mentha pulegium reduces the pain in the acute stage more than chronic stage. However, more research is needed to find out the effective antinociceptive compounds in Mentha pulegium

The effect of cabergoline on level of liver enzymes

زمینه و هدف: به علت اهمیت نقش کبد در ارتباط با متابولیسم داروهای شیمیایی و سنتز پروتئین های پلاسما و استفاده زیاد از داروی کابرگولین در درمان بیماری هیپرپرولاکتینمیا، پارکینسون و برخی اختلالات دیگر این مطالعه با هدف بررسی اثر داروی کابرگولین بر غلظت پلاسمایی آنزیم های کبدی و پروتئین های سرم انجام گرفت. روش بررسی: در این مطالعه تجربی 40 سر موش صحرایی نر بالغ از نژاد ویستار به 5 گروه 8 تایی تقسیم شدند. گروه های تجربی 1 و 2 و 3 به ترتیب مقادیر 1، 5/0 و ( (mg/kg 1/0 دارو را دریافت کردند. گروه کنترل هیچ دارویی دریافت نکرد و گروه شاهد فقط آب مقطر (حلال دارو) دریافت کرد. تجویز دارو به صورت زیر پوستی و به مدت 14روز انجام شد. بعد از پایان دوره آزمایش نمونه های خونی از کلیه گروه ها تهیه و آنزیم های کبدی شامل آلانین ترانس آمیناز (ALT)، آسپارتات ترانس آمیناز (AST)، آلکالین فسفاتاز (ALP)، آلبومین و پروتئین توتال اندازه گیری شد. نتایج به دست آمده از آزمایشات بوسیله آنالیز آماری غیر پارامتری (K Independent Sample) تجزیه و تحلیل گردید. یافته ها: بین گروه های تجربی دریافت کننده مقادیر مختلف دارو و گروه کنترل اختلاف معنی داری در میزان آنزیم های ALT و AST مشاهده نگردید. میزان آنزیمALP در گروه های دریافت کننده مقادیر 5/0 و حداکثر یک میلی گرم بر کیلوگرم (7/28±471 و 06/53±474) نسبت به گروه کنترل (64/31±551) کاهش معنی داری را نشان داد (05/0

Effects of Silybum marianum Aqueous Extract and L-carnitine on Stereological Changes in Diazinon-Treated Rat Liver

As an organophosphorus, Diazinon (DZN) impairs liver tissue function by inhibiting acetylcholinesterase and causing oxidative stress. In this study, the effects of Silybum marianum aqueous extract (SMAE) and L-carnitine (LC) on the stereological and histopathological changes of the liver in DZN-treated male rats were investigated. The rats in this study were placed into 9 groups of 8 each containing control, placebo, and a combination of DZN, SMAE, and LC. The animals received SMAE and chemicals orally for 30 days. At last, the liver tissue of all animals was removed. Then, tissue sections from the liver were provided to study the stereological markers including liver volume and weight, hepatocytes’ volume, central venous volume, sinusoidal volume, connective tissue volume, inflammation rate, and a number of the hepatocytes’ nuclei. Also, the sample tissues were evaluated histopathologically. Treatment with DZN significantly reduced the liver volume and weight, hepatocyte volume, central venous volume, sinusoidal volume, and hepatocyte nucleus number compared to placebo and control but it significantly increased the inflammation and volume of liver’s connective tissue. However, co-administration of SMAE and LC with DZN improved liver volume and weight, hepatocyte volume, central venous volume, sinusoidal volume, connective tissue volume, and hepatocyte nucleus number alone compared to the DZN treatment. Liver inflammation was also significantly decreased compared to the DZN treatment but comparing to the placebo and control groups, it increased significantly. Simultaneous administration of SMAE and LC has protective effects on liver tissue and can reduce DZN-induced liver injury in rats

Effects of Silybum marianum Aqueous Extract and L-carnitine on Stereological Changes in Diazinon-Treated Rat Liver

As an organophosphorus, Diazinon (DZN) impairs liver tissue function by inhibiting acetylcholinesterase and causing oxidative stress. In this study, the effects of Silybum marianum aqueous extract (SMAE) and L-carnitine (LC) on the stereological and histopathological changes of the liver in DZN-treated male rats were investigated. The rats in this study were placed into 9 groups of 8 each containing control, placebo, and a combination of DZN, SMAE, and LC. The animals received SMAE and chemicals orally for 30 days. At last, the liver tissue of all animals was removed. Then, tissue sections from the liver were provided to study the stereological markers including liver volume and weight, hepatocytes’ volume, central venous volume, sinusoidal volume, connective tissue volume, inflammation rate, and a number of the hepatocytes’ nuclei. Also, the sample tissues were evaluated histopathologically. Treatment with DZN significantly reduced the liver volume and weight, hepatocyte volume, central venous volume, sinusoidal volume, and hepatocyte nucleus number compared to placebo and control but it significantly increased the inflammation and volume of liver’s connective tissue. However, co-administration of SMAE and LC with DZN improved liver volume and weight, hepatocyte volume, central venous volume, sinusoidal volume, connective tissue volume, and hepatocyte nucleus number alone compared to the DZN treatment. Liver inflammation was also significantly decreased compared to the DZN treatment but comparing to the placebo and control groups, it increased significantly. Simultaneous administration of SMAE and LC has protective effects on liver tissue and can reduce DZN-induced liver injury in rats

Integration of Frequency Dependent Soil Electrical Properties in Grounding Electrode Circuit Model

The effect of frequency dependent soil properties on the impedance and transient response of the grounding electrode was investigated. The frequency dependent soil models as proposed by Scott, Smith-Longmire, and Visacro-Alipio were critically reviewed. A novel method was proposed to integrate the frequency dependent soil electrical properties in the circuit model of grounding electrode. To validate the application of the method in circuit model, the voltage responses of the grounding electrode obtained by the circuit and electromagnetic models were compared. The voltage responses obtained by the circuit and electromagnetic models were in excellent agreement in terms of voltage peaks and wave shapes. The differences between voltage peaks obtained by the circuit and electromagnetic models were found less than 1%

Bond Strength of White Mineral Trioxide Aggregate with and without Disodium Hydrogen Phosphate with Different Liquid-to-Powder Ratios

Introduction: Mineral trioxide aggregate (MTA) can be used in the treatment of irritated vital pulp and repair of root perforations. However, the initial reaction of inflammatory cells to this material and also its setting time are not ideal. Studies have shown that disodium hydrogen phosphate (DHP), decreases the setting time of MTA, with no effect on its pH. This study was undertaken to evaluate the effect of DHP on push-out bond strength of MTA at different liquid-to-powder ratios. Methods and Materials: A total of 120 samples were prepared from the middle third of the roots of single-rooted teeth for evaluation of push-out bond strength. The push-out bond strength was measured in both groups after 72 h at different liquid-to-powder ratios, including 0.33:1, 0.5:1 and 0.6:1. Factorial ANOVA and Tukey’s HSD post-hoc tests were used to compare the differences between the independent groups. Statistical significant was set at P&lt;0.05. Results: The push-out bond strengths of pure MTA and MTA+DHP groups were 10.96±5.78 and 13.32±5.03, respectively. Tukey’s HSD post-hoc test revealed significant differences between the two groups. Furthermore, there were no interactive effect between material and the liquid: powder ratio. Conclusion: Incorporation of DHP into MTA resulted in an increase in push-out bond strength of MTA, and an increase in liquid-to-powder ratio resulted in a decrease in push-out bond strength.Keywords: Disodium Hydrogen Phosphate; Mineral Trioxide Aggregate; Push-Out Test; Root Canal Filling Materials; Root Canal Therapy

Compressive Strength of Mineral Trioxide Aggregate with and without Disodium Hydrogen Phosphate at Different Mixing Ratios

Introduction: Mineral Trioxide Aggregate (MTA) is a substance with favorable physical-mechanical properties. Disodium hydrogen phosphate(DHP) is sometimes added to MTA to reduce its setting time. Therefore, this study was conducted to evaluate the effect of various ratios of liquid to powder of white MTA (WMTA) and addition of DHP on its compressive strength. Methods and Materials: One hundred and twenty samples were prepared with a two-piece stainless steel mold with a height of 6 mm and a diameter of 4 mm in order to evaluate the compressive strength where WMTA was used in 60 samples and DHP in white MTA composition (DHPWMTA) was used in other 60 samples. The compressive strength of WMTA and DHPWMTA was measured in various ratios of liquid to powder including 50, 60 and 70% and at 24 h and 21 days (n=10). Univariate Analysis of Variance test with SPSS 16 software were used to determine the difference between groups. The level of significance was set at 0.05. Results: The maximum and minimum compressive strength of WMTA groups were 63.25±1.96 (50% ratio and 21 days) and 37.79±1.28 (70% ratio and 24 h), respectively. The maximum and minimum compressive strength of DHPWMTA groups were 63.96±1.40 (60% ratio and 21 days) and 37.37±1.62 (70% ratio and 24 h), respectively. The effect of each of factors (type of material, powder to liquid ratio and time) alone were significant on the compressive strength (P&lt;0.05). However, the interactive effect of three factors (type of material, powder to liquid ratio and time) were not statistically significant on compressive strength (P&gt;0.05). Conclusion: Adding 2.5 wt% of DHP to white MTA increased samples compressive strength. Compressive strength in liquid to powder ratios of 50 and 60% compare to 70% and at 21 days compared to 24 h was high.Keywords: Compressive Strength; Disodium Hydrogen Phosphate; Mineral Trioxide Aggregat

A Scanning Electron Microscope Study on the Effect of an Experimental Irrigation Solution on Smear Layer Removal

Introduction: The aim of this in vitro study was to evaluate the effect of an experimental irrigation solution, containing two different concentrations of papain, Tween 80, 2% chlorhexidine and EDTA, on removal of the smear layer. Methods and Materials: Thirty-six single-rooted teeth were divided into two experimental groups (n=12) and two positive and negative control groups of six. The canals were prepared with BioRaCe instruments up to BR7 (60/0.02). In group 1, canals were irrigated with a combination of 1% papain, 17% EDTA, Tween 80 and 2% CHX; in group 2, canals were irrigated with a combination of 0.1% papain, 17% EDTA, Tween 80 and 2% CHX. In group 3 (the negative control), the canal was irrigated with 2.5% NaOCl during instrumentation and at the end of preparation with 1 mL of 17% EDTA was used; in group 4 (positive control), normal saline was used for irrigation. The amount of the remaining smear layer was quantified according to Hulsmann method using scanning electron microscopy (SEM). Data was analyzed by the Kruskal-Wallis and Mann-Whitney tests. Results: Two-by-two comparisons of the groups revealed no significant differences in terms of smear layer removal at different canal sections between the negative control group (standard regiment for smear layer removal) and 1% papain groups (P&lt;0.05). Conclusion: Under the limitations of the present study, combination of 1% papain, EDTA, 2% chlorhexidine and Tween 80 can effectively remove smear layer from canal walls