Background and Aims: When composite resin polymerizes, shrinkage stresses tend to produce gaps at the tooth/ restoration interfaces. surface sealants may reduce or avoid problems related to the marginal interface. The aim of this study was to evaluate the effect of two different surface sealants (Fortify and Optiguard) on the microleakage of class V resin composite restorations.Materials and Methods: Twenty three sound noncarious molars were collected. Totally, 45 Class V cavities with the occlusal margins in enamel and cervical margins in cementum were prepared in both buccal and lingual surfaces. The specimens were randomly assigned in three groups (15 cavities in each group) and then restored with a resin composite. After the finishing and polishing procedures, the restorations in each group were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and then immersed in a 50% silver nitrate solution (tracer agent) for four hours, sectioned longitudinally and analyzed for leakage using a stereomicroscope in a blind manner. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the three groups using the Kruskall-Wallis and the Mann-Whitney U tests.Results: Microleakage was found in all groups at both occlusal and cervical margins. Significantly greater leakage was observed at the cervical margins compared to the enamel margins of the material groups (P=0.005).There was no statistically significant difference among the groups at occlusal margins (P=0.66). In the cervical region, Fortify showed improved results and statistically presented the lowest degree of microleakage (P=0.003).Conclusion: The used sealant materials presented different rates of effectiveness and Fortify decreased marginal microleakage significantly.

Background: Post operative intraocular infection (endophthalmitis) is a rare but devastating complication. The present study aimed to determine the antibiotic susceptibility pattern of ocular surface bacterial flora isolated preoperatively from patients undergoing intraocular surgery.Materials and methods: In a prospective study, 269 patients scheduled for anterior segment surgeries, were enrolled, for whom lid and conjunctival cultures were obtained on the day of surgery before application of povidone – iodine or antibiotic drops. Bacterial isolates were identified and tested for antibiotics susceptibility using Kirby-Bauer discdiffusion technique.Results: Of 269 studied eyes, 127(47.2%) were male. In 101 (37.5%) cases bacterial growth was positive. Isolated bacteria in order of frequency were coagulase negative staphylococci (CNS) (90.0%), coagulase positive staphylococci (CPS) (4%), diphteroid (3%), gram negative bacillus (2%) and streptococci (1%). Totally, 95% of coagulase negative staphylococci were susceptible to vancomycin, amikacin and gentamicin. Less than 70% of isolated CNS were sensitive to ceftriaxon, tetracyelin, erythromycin, oxacillin, cotrimaxazole, and penicillin.Conclusion: Preoperative ocular surface isolates of CNS seems to be most sensitive to vancomycin, amikacin and gentamicin. Thus, preoperative application of these medications into ocular surface is suggested.

2Background: Antibiotic resistance represents a critical global concern within the medical community, posing significant challenges in the treatment of infections caused by drug-resistant pathogens. Over the years, broad-spectrum fluoroquinolones have been extensively used to treat infections caused by both Gram-positive and Gram-negative bacteria, including Pseudomonas aeruginosa. In this study, we decided to assess the prevalence of plasmid-mediated quinolone resistance mechanisms among clinical isolates of P. aeruginosa in Ardabil hospitals. Methods: We analyzed a total of 200 clinical isolates of P. aeruginosa, collected between June 2019 and May 2023. The antibiotic resistance profiles of these strains against various fluoroquinolone antibiotics were determined using the disk diffusion method. Additionally, we investigated the presence of qnrA, qnrB, qnrC, qnrD, and qnrS genes through polymerase chain reaction (PCR) analysis. Furthermore, we assessed the expression levels of efflux pump genes and outer membrane porin genes using the quantitative reverse transcription PCR (qRT-PCR) in fluoroquinolone-resistant P. aeruginosa strains. Results: Our findings revealed that 69% of P. aeruginosa strains were resistant to fluoroquinolones. The resistance rates for different fluoroquinolones were as follows: ciprofloxacin 55.5%, ofloxacin 62%, norfloxacin 53.5%, lomefloxacin 55.3%, and levofloxacin 55.5%. Notably, 78.9% of these strains exhibited multidrug resistance (MDR). Among the qnr genes, qnrB was the most prevalent (2.9%). No other qnr genes were identified. Interestingly, 75% of P. aeruginosa strains carrying the qnrB gene showed overexpression of efflux pump genes, while 100% exhibited down-regulation of the oprD gene. Conclusion: Given the high prevalence of fluoroquinolone-resistant P. aeruginosa clinical isolates in Ardabil hospitals and the multifactorial nature of resistance, continuous monitoring of antibiotic resistance trends and understanding the underlying resistance mechanisms are crucial for selecting appropriate treatment strategies.

One of the most important problems in the world nowadays is the soil erosion, which reduces soil fertility, increases sediment concentration in rivers and dam’ s reservoirs. For this purpose, the present study was conducted to investigate soil surface resistance changes using a polyvinyl acetate polymer with rates of 5, 10, 15, 20 and 25 ml and application concentrations of 5, 10, 15, 20, 25 percent in laboratory conditions and plot scale. The polymer application with a concentration of 25 percent and a rate of 25 ml in the level of 0. 79 m2 had the most soil surface resistance with a rate of 3. 3 kg cm-2. According to the obtained results and the economic cost (each litre of polyvinyl acetate of 100000 Rials) can state that the level of 15 percent can be selected as an optimum level for increasing soil surface resistance. With regard to the results it can be concluded that the used polymer in addition to the increasing soil surface resistance can have an effect on the soil conservation and control of water erosion.

Underwater vehicles in industrial applications, have various control surfaces for stability, maneuverability, gudance and control. These control surfaces affect the body hydrodynamic characteristics, including the resistance forces and the form of the generated wave due to the motion of the vehicle near the free surface. In this paper the effect of a vertical control surface on the hydrodynamic characteristics of an underwater vehicle near free surface is studied using Boundary Element Method.Results, including characteristics of free surface wave, pressure coefficient and wave resistance are calculated for Froude numbers in the range of 0.1-0.5 and non dimensional submergence depths of 1.25, 2.25, 3.5 & 4.5 for the bare model and model with control surface. Comparing BEM and experimental results shows the discrepancy of less than 3% for maximum free surface wave height and 17% for wave resistance. Predicted results indicates that control surface causes an increase of about 13% in maximum free surface wave height and 16% in wave resistance. This increment is due to the interaction of the main body with control surface and also direct relation of wave resistance with free surface wave height.

Need to increase urban infrastructure and lack of access to suitable quality soil increased demand for new methods for soil improvement. Recently, improving the parameters of strength, stiffness and permeability of sand under microbial induced calcite precipitation has received much attention from geotechnical experts as innovative and environmentally friendly methods. Therefore, it is very important to study the parameters affecting the biological improvement technique and find the ideal combination to increase efficiency and reduce costs. The main purpose of this paper is to investigate the effect of the variability of cementation solution molarity, bacterial optical density and curing time (three levels of variation for each) on the parameters of deviation and effective stresses for biologically improved sand under undrained triaxial compression test. The sand used in this study is a SP soil according to the unified soil classification system, and the adopted micro-organism is Bacillus pasteurii as the urease-positive bacterium. The response surface methodology was used to optimize the stress parameters in the improved sand and to significantly reduce the number of experiments. The experiments were designed using a Box-Behnken design with five central points. Three-dimensional schemes and regression model contours were used to evaluate and compare the effect of each variable. In this method, according to the analysis of variance for the data, the effect of all variables on the responses was significant and the optimal values for effective and deviation stresses were 958.2 and 1032.4 (kPa), respectively. Due to the slope of the curves, the molarity of the cementation solution had the greatest effect on the responses, and the effect of bacterial optical density on effective stress was less than deviation stress, that may be due to the accumulation of excess bacteria (lack of nutrients) and its impact on excess pore water pressure.

In this study, electrical discharge process was used to increase surface wear resistance of pure aluminum. Pulse-on-time and pulse current were considered as the input parameters of the electrical discharge process. Experimental results revealed that the electrical discharge process is a successful method for improving the surface wear resistance of aluminum, to the effect that it has greatly increased the surface wear resistance of aluminum parts. The results indicate that with increasing the input parameters (pulse-on-time and pulse current), weight loss of the aluminum specimens is reduced and wear resistance increases. The XRD analysis demonstrated that Al3Ni2 and AlCu intermetallic compound and Al4C3 were formed on the alloyed surface. The presence of these compounds and hard particles on the surface increases the wear resistance. Also, friction coefficient measurements showed that after electrical discharge process and improving surface wear resistance, the friction coefficient slightly increased due to the presence of hard particles on the alloyed surface.

Introduction: Kojic acid with the chemical structure of 5-hydroxy-2-hydroxymethyl-ˠ-Piron is an organic acid that is biologically produced through aerobic fermentation process by using various substrates and via the function of variety of fungi. This study was aimed to study the optimization of Kojic acid production by Locally Isolated Fungi Aspergillus sp., using ‘Response surface Methodology’.Materials and Methods: Kojic acid was produced by fermentation of isolated strain of genus Aspergillus in submerged culture medium. Initial investigation in Kojic acid production process was performed via Plackett-Burman method and by using different nitrogen sources such as yeast extract, peptone, ammonium sulfate, ammonium chloride, urea as well as different carbon sources, including fructose, sucrose, glucose, lactose and maltose.Results: Based on our study, peptone and glucose were the most effective factors with carbon and nitrogen sources in production of kojic acid (P<0.05). The next step was production of 34.4g/L kojic acid by optimizing the effect of environmental factors such as temperature, pH, glucose and peptones, such as carbon and nitrogen sources, used in production of kojic acid and by employing ‘Response surface Methodology’.Conclusion: Based on the results of this study, the maximum production of kojic acid can be achieved by using; glucose (%8.71), peptone (37.4%), temperature (29.9oC) and adjusting pH to 6.75 in the production process.

resistance is one of the fundamental Quranic values in the cause of the development of the Islamic society and the formation of the Islamic civilization, which means standing and resisting against something has upset the balance in internal and external dimensions. The formation of this value in the society as one of the methods of the conventional model of human life in the fields of human life; So that its manifestation can be observed in the totality of social behaviors, it is called the culture of resistance (Problem statement). The purpose of this article is the achievement of the engineering process of this value in a society based on the growth-oriented thought (ideological) system of the Holy Quran (Purpose). Now the question is what process does the Holy Quran propose in order to engineer the culture of resistance in the society? (Question). The necessity of examining this issue is clear considering the emphasis of religious teachings on this value and the need for Islamic societies, especially considering the current conditions of Islam and the need for convergence and coordination between the resistance front (Necessity). The research method in stating the engineering process and its components is qualitative content analysis with an analogy approach (Method). The findings of the research show that the engineering process of resistance culture is based on a self-awareness and purposefulness, according to the idea of Quranic growth, in a three-stage process that leads to the happiness of man and human society (Conclusion).