Characteristics of Cantilever Retaining Wall Composed of Upper Wall and Lower Wall by Physical Testing

Based on the finite element method, the earth pressure and deformation of the cantilever retaining wall composed of upper wall and lower wall are compared and analyzed. The results show that the maximum lateral displacement of the fill occurs near the top of the upper wall, the lower wall has the tendency of overturning to the free surface, while the upper wall has a certain deviation from the free surface. The vertical earth pressure acting on the heel plate of the upper wall and the lower wall presents non-linear characteristics. When the cantilever retaining wall composed of upper wall and lower wall is unstable, there are two slip surfaces in the filling. The first slip surface runs through the filling based on the heel plate root of the lower wall, and the second slip surface runs through the upper filling based on the heel plate root of the upper wall.

COMPARISON OF THE STATE OF THE MAXILLARY SINUSES IN A NEW CORONAVIRUS INFECTION COVID-19 AND ACUTE RESPIRATORY VIRAL INFECTION

The aim of the study was to identify possible changes in the maxillary sinuses during new coronavirus infection in comparison with the changes in the sinuses occurring during acute respiratory infections and to correlate the gender structure of the study groups. Material and methods. The study included 40 patients (18 women and 22 men) with a confirmed new coronavirus infection, hospitalized at the Covid Hospital Clinics of Samara State Medical University in 2020. All patients underwent multispiral computed tomography of the paranasal sinuses on a Ge revolution Evo 128 tomograph on the 10th day after the appearance of the first clinical symptoms. We also examined a control group of patients with acute respiratory infections with similar complaints of impaired sense of smell, rhinorrhea, and upper maxillary sinus discomfort. This group also included 40 people (24 women and 16 men). Statistical processing of the study results was performed using Microsoft Excel software package, the Mann – Whitney method of statistical significance calculation was used. Results and discussions. In 18 (45%) patients with a confirmed new coronavirus infection, a slight mucosal thickening along the lower wall of the maxillary sinuses was found symmetrically on both sides. Six (15%) of them were women and 12 (30%) were men. The age of the examined patients ranged from 31 to 83 years. Chronic sinusitis was noted in the history of 8 (20%) of the examined patients. In 6 (15%) patients with chronic sinusitis no abnormalities were detected in the maxillary sinuses at the time of examination. Two of them had parietal thickening of the mucous membrane along the lower wall of the maxillary sinuses. In the control group, there was significant symmetric parietal thickening of the mucous membrane of the paranasal sinuses in 24 (60%) examined patients (14 women and 10 men). There were no statistically significant differences in the prevalence of changes in the studied and control groups. Conclusion. According to the results of this study, there were no data on the pattern of occurrence of changes in the mucosa of the maxillary sinuses in new coronavirus infection with gender background or the presence of chronic inflammation of the maxillary sinuses in the history compared with the control group of examined patients after acute respiratory infections.

The effect of controlled vibrations on Rayleigh-Benard convection

The paper presents the results of a numerical study of convective heat transfer in a long horizontal layer heated from below with and without the vibration effect of the lower wall. The simulation was carried out on the basis of solving the Navier-Stokes 2D equations for an incompressible fluid in the Boussinesq approximation. It is shown that the influence of vibrations of the lower heated wall on the wave number of the convective flow roll structure, on the time and on the critical Rayleigh number of convection. The influence of controlled harmonic vibrations of wall on the structure of convective flow in the Rayleigh-Benard problem has been investigated. It is shown that the wave number of the periodic convective structure, the critical Rayleigh number, and the time of occurrence of Rayleigh-Benard convection under the vertical vibration effect on the horizontal layer from the lower wall are reduced.

Prediction for Postpartum Hemorrhage of Placenta Previa Patients through MRI Using Self-Adaptive Edge Detection Algorithm

The study aimed to explore the application value of MRI images based on the optimized self-adaptive edge detection algorithm in the diagnosis of placenta previa and in the prediction of postpartum hemorrhage. Specifically, a self-adaptive edge detection algorithm was constructed based on optimized edge operators, with the nearest scale parameters analyzed. It was then used to process the MRI images of 36 patients with placenta previa. MRI images of different types of placenta previa were analyzed. The results found that the placenta of the complete placenta previa was attached to the lower wall of the uterus and covered the internal cervix in U shape, and the placenta adhered to the anterior and lower wall of the uterus, with widespread placenta accreta noted. With the results of cesarean section as the standard, it was observed that 2 cases of complete placenta previa were diagnosed as partial placenta previa. The diagnostic accuracy rate was 94.44%, which was not notably different from the results of cesarean section p > 0.05 . The postpartum hemorrhage rate and hysterectomy rate of complete placenta previa were higher than partial placenta previa and marginal placenta previa, and the difference was notable p < 0.05 , but no notable differences were noted in placenta adhesion, placenta accreta, neonatal death, and neonatal asphyxia between the three types of placenta previa p > 0.05 . The incidence of thinned myometrium, placenta penetrating the cervix, placenta accreta, and uneven placental signal in patients with postpartum hemorrhage was higher versus those without postpartum hemorrhage, and the difference was notable p < 0.05 . In a word, MRI images based on the self-adaptive edge detection algorithm can clearly show the status of placenta previa and exhibit better diagnosis effects and a higher accuracy rate. The thinned myometrium, the placenta penetrating the cervix, placenta accreta, and uneven placental signal may be the related risk factors for postpartum hemorrhage in patients with placenta previa.

Case report of two patients with silent sinus syndrome

SMS is a rare pathology of the paranasal sinuses, accompanied by such symptoms as pain in the eye area, enophthalmos and hypophthalmos on the side of the localization of the process, facial asymmetry caused by a decrease in the volume of the maxillary sinus due to its atelectasis in the presence of chronic inflammation in it. The disease, as a rule, proceeds under the primary diagnosis of chronic rhinosinusitis. The main pathogenetic link of the disease is generally accepted as the block of the anastomosis and the emergence of the valve mechanism of ventilation of the maxillary sinus. However, the immediate cause of the onset of atelectasis remains a subject of discussion to this day. The only effective surgical treatment is to restore ventilation of the maxillary sinus by expanding the anastomosis and eliminating the cause of its block. With a pronounced asymmetry of the face due to the lowering of the orbit, the plastic of the lower wall of the orbit is performed. The article discusses modern ideas about the silent sinus syndrome, its etiology, pathogenesis, clinical course and treatment tactics for patients, presents two clinical observations of patients with silent sinus syndrome and describes the options for surgical treatment and its results.

Unsteady nano-bioconvective channel flow with effect of nth order chemical reaction

Nanofluid bioconvective channel flow is an essential aspect of the recent healthcare industry applications, such as biomedical processing systems. Thus, the present work examined the influence of nth order chemical reaction in an unsteady nanofluid bioconvective channel flow in a horizontal microchannel with expanding/contracting walls. The suitable form of the similarity transformation is exercised to transform the governing boundary layer equations into a more straightforward form of system to ease the computation process. The Runge–Kutta method of fifth-order integration technique solved the reduced boundary layer system and generated the numerical results as the governing parameters vary. It is found that the destructive second-order chemical reaction enhances the mass transfer rate at the lower wall but deteriorates the mass transfer rate at the upper wall. The upper channel wall has a better heat transfer rate than the lower wall when the Reynolds number increases.

ANATOMICAL PREDICTIONS OF DEVELOPMENT OF RHINOSINUSITIS AND ITS COMPLICATIONS

Background. The anatomical structure of the paranasal sinuses of a person predetermines the risk of development, diversity of presentation, possibility of complications and features of surgical treatment of rhinosinusitis. Objective: of our study was to determine the thickness and density of the walls of the maxillary and frontal sinuses, which are potentially dangerous in terms of the development of complications. Materials and methods: Our study involved 121 subjects without any ENT diseases, who underwent SCT examination due to the reasons that were not related to abnormalities of ENT organs. Thickness and density in the region of the lower (orbital) wall and posterior (cerebral) wall of the frontal sinus were calculated. Results and Discussion: The maximum density was characteristic of the lower wall of the frontal sinus under physiological conditions and appeared 107.96 ± 201.64 Hu, the minimum for the lower wall was -29.98 ± 208.54 Hu. The thickness of the bone tissue in the frontal sinus was 4.05 ± 2.04 mm. Conclusion: The minimum density and thickness of the lower and posterior walls of the frontal sinus and upper and lower walls of the maxillary sinus was established under physiological conditions. The density of the posterior wall was found to be 25.4% lower than the density of the lower wall, and the thickness 22.2% lower.