Urban Tunneling Risk Management: Ground Settlement Assessment through Proportional Hazards Modeling

Nowadays, tunnel excavation plays a major role in the development of countries. Due to the complex and challenging ground conditions, a comprehensive study and analysis must be done before, during, and after the excavation of tunnels. Hence, the importance of study and evaluation of ground settlement is dramatically increased since many tunnel projects are performed in urban areas, where there are plenty of constructions, buildings, and facilities. For this reason, the control and prediction of ground settlement is one of the complicated topics in the field of risk engineering. Therefore, in this paper, the proportional hazard model (PHM) is used to analyze and study the ground settlement induced by Tabriz Metro Line 2 (TML2) tunneling. The PHM method is a semi-parametric regression method that can enter environmental conditions or factors affecting settlement probability. These influential factors are used as risk factors in the analysis. After establishing a database for a case study and using a proportional hazard model for surface settlement analysis, and then by evaluating the effect of environmental conditions on the ground surface settlement, it has been found that the risk factors of grouting pressure behind the segment, the ratio of tunnel depth to groundwater level, and drained cohesion strength at a significant level of 5% have a direct effect on the probability of settlement. The results also showed that the effect of grout injection pressure on ground subsidence is more than other parameters, and with increasing injection pressure, the probability of exceeding safe subsidence values decreases. In addition, it has been found that increasing the risk factor for the ratio of tunnel depth to groundwater level reduces the probability of exceeding the safe ground settlement. Finally, increasing the number of risk factors for drained cohesion strength increases the probability of exceeding safe settlement

Comparison of different sizes of Iranian bone allograft particles (CenoBone) in preserving grafted socket dimensions

Introduction: Teeth are extracted for a variety of reasons, including severe decay, endodontic problems, severe periodontal destruction, inadequate residual crown structure, root resorption, iatrogenic factors such as perforations, injuries due to trauma, and cosmetic problems. Aim of the research: To compare different sizes of Iranian bone allograft particles (CenoBone) in preserving grafted socket dimensions. Material and methods: It was an experimental study. Twenty healthy patients who had 25 unpreserved single-rooted teeth were included in the study. Patients were randomly divided into two equal groups. In the first group, allograft particles with a size of 150-500 mu m and in the second group, particles with a size of 1000-2000 pm were placed in the socket. Then, Iranian resorbable membrane (CenoBone) was placed on the socket openings and buccal wall and was initially closed by a coronalizing buccal flap. Buccal wall height and ridge width in the two groups were compared immediately after surgery and 4 months after surgery with radiological evaluation (cone-beam computed tomography - CBCT) of the region. Results: In both groups the horizontal dimension was significantly different after treatment (p < 0.002). In both groups the vertical height was significantly different after treatment (first group: p < 0.001, second group: p < 0.003). Conclusions: Use of CenoBone to fill bone socket is essential to preservation alveolar bone dimensions, because use of this material improves soft and hard tissue

Histological Evaluation of Wound Healing Effect of Topical Phenytoin on Rat Hard Palate Mucosa

Extension and duration of wound healing following periodontal surgery are very important. The aim of present study was histological evaluation of wound healing of topical phenytoin on rat hard palate mucosa. A total of 60 rats were randomly divided into four groups of 15(n=15). A standard 4×6 mm diameter wound was created on the hard oral palate of each rat. The control group were given an equal volume of normal saline. The group of phenytoin and chitosan gel received the topical gel of phenytoin and chitosan, respectively. The fourth group were received a dosage of 10mg phenytoin daily. Five rats each were sacrificed and all sections were examined for histologic changes by light microscopy. The mean number of neutrophils, fibroblasts, macrophages, epithelialization, and the density of collagen fibers were evaluated in each group. Data were analyzed using ANOVA and Kruskal-Wallis tests. The number of fibroblasts and the rate of epithelialization in the group of phenytoin gel were significantly higher on the 7th day than the control group (P <0.05). The density of collagen fibers on the 14th day was significantly higher in the group of phenytoin gel than the control group (P <0.05). It can be concluded that topical phenytoin to promote wound healing of rat hard palate

Effect of the lateral earth pressure coefficient on settlements during mechanized tunneling

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The antibacterial activity of “Satureja hortensis” extract and essential oil against oral bacteria

Background: Recently, there has been an increasing growth in research on medical plant's effect on dental plaque bacteria. The aim of this study was to determine the antibacterial effects of Satureja hortensis extract and its essential oil (EO) on Streptococcus salivarius, Streptococcus sanguis, and Streptococcus mutans as important bacteria in early supragingival dental plaque formation. Materials and Methods: In this in vitro study, different concentrations of S. hortensis extract and its EO were prepared using double dilution method. The disc diffusion method was used to determine antibacterial activity. Based on these measurements, the minimal inhibitory concentration value was reported for each bacterium. Antibiotics used as positive controls in this study were erythromycin (15 μg) and tetracycline (30 μg). t-test and ANOVA were used for statistical analysis (P < 0.05). Results: Aqueous and methanolic extract did not show significant antibacterial activity, but the EO significantly inhibited the growth of the test bacteria compared to positive control (P < 0.05). High concentrations of EO processed greater antimicrobial effects against three oral bacteria than other low concentrations (P < 0.0001). For S. mutans, the inhibition effect of tetracycline 30 μg was similar with 50% (P = 0.789) and 25% (P = 0.158) dosages of the EO. For S. salivarius, the effect of tetracycline 30 μg was similar to 50% dosages of the EO (P = 0.122). For S. sanguis, the effect of erythromycin 15 μg was lower than 50% (P = 0.0006) and 25% (P = 0.003) dosages of the EO. The inhibition effects of all concentrations of EO were higher for S. sanguis. S. salivarius and S. sanguis are more sensitive than S. mutans to S. hortensis EO. Conclusion: Due to the strong antibacterial effect of S. hortensis EO on the oral bacteria growth, it can be served as herbal mouth rinse, while to confirm this antibacterial effect, further clinical studies are necessary

Antibacterial Effect of Juglans Regia Bark against Oral Pathologic Bacteria

Background. In this study antimicrobial effect of ethanolic and aqueous extracts of Juglans regia bark in Iran was evaluated on four different oral bacteria, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis, and Staphylococcus aureus. Methods. Aqueous and ethanol extracts of Juglans regia bark were prepared by using disk diffusion technique and Minimal Inhibitory Concentration (MIC) methods. Tetracycline 30 μg and Erythromycin 15 μg were used as positive control and water as negative control in disk diffusion and MIC methods. Data were analyzed by ANOVA test. Results. The results showed that S. sanguis and S. mutans were the most sensitive and the most resistant bacteria against ethanolic and aqueous extracts, respectively. Ethanolic extract had significant antibacterial effect against all tested bacteria. Aqueous extract did not show antibacterial effect on S. mutans, in contrast to ethanolic extract. Aqueous extract had significantly antibacterial effect against Staphylococcus aureus, S. salivarius, and S. sanguis compared to control (P<0.0001), but it did not show effect on S. mutans when compared with Erythromycin. According to the obtained MIC values, ethanol extract of Juglans regia bark had the lowest rate. Conclusion. The results may provide the basis for using natural antimicrobial substance for oral hygiene prophylaxis purposes

Frequency and Pattern of IgE-mediated Sensitization to Aero and Food Allergens in Ahvaz, Province of Khuzestan in Southwestern Iran

Efficient diagnosis of allergy and proper treatment need identification of the causative allergens eliciting clinical symptoms. The present study was performed to identify the most common aero- and food allergens and determine the pattern of sensitization among people of Ahvaz (southwestern Iran), one of the most polluted cities worldwide. Based on the physical examination and medical records, patients were referred to the Allergy laboratory for "in vitro" IgE determination. Specific and total IgE was determined by the ImmunoCAP system (Thermo Fisher-Phadia, Uppsala, Sweden). A total of 666 consecutive patients (51.1% female) were tested for 202 different allergens. The majority of requests (57%) belonged to food allergens. Sensitization to at least one allergen was found in 47.6% of patients. In a selected group of allergens for which specific IgE had been tested in at least 100 patients, the most common sensitizing aeroallergens were Russian thistle, grass pollen, and willow; while wheat, honey, and shrimp were the most frequent food allergens, respectively. Sensitization profiles based on measurement of specific IgE indicated that Russian thistle, grasses, and wheat were the most prevalent allergens in people with allergic symptoms living in Ahvaz.status: publishe