One-Dimensional and Axisymmetric Numerical Simulation of a Single-Stage Gas Gun

Abstract One dimensional and axisymmetric numerical simulation of a single-stage gas gun is being conducted in this study. Axisymmetric viscous and compressible flow equations has been numerically solved by van Leer flux vector splitting scheme, with space and time second order accuracy by using moving boundary. One dimensional inviscid compressible flow has been numerically solved by secondorder Roe TVD scheme. For the turbulent flow in axisymmetric simulation is used the Baldwin-Lomax model. The projectile velocity for different governing parameters for a transonic and supersonic gas gun is obtained and investigated. The transonic gas gun results illustrate that the second-order TVD Roe scheme has a higher accuracy than the Van Leer flux vector splitting scheme for low Mach number flows. The supersonic gas gun results are in an excellent agreement with the one-dimensional and axisymmetric simulation. The comparison between two methods of solution shows that the one-dimensional and inviscid flow approximation are sufficient for simulation of flow in a single-stage gas gun and does not need to the axisymmetric simulation

Analytical Solution for Different Profiles of Fin with Temperature-Dependent Thermal Conductivity

Three different profiles of the straight fin that has a temperature-dependent thermal conductivity are investigated by differential transformation method (DTM) and compared with numerical solution. Fin profiles are rectangular, convex, and exponential. For validation of the DTM, the heat equation is solved numerically by the fourth-order Runge-Kutta method. The temperature distribution, fin efficiency, and fin heat transfer rate are presented for three fin profiles and a range of values of heat transfer parameters. DTM results indicate that series converge rapidly with high accuracy. The efficiency and base temperature of the exponential profile are higher than the rectangular and the convex profiles. The results indicate that the numerical data and analytical method are in agreement with each other

Comparison of clinical, para-clinical and laboratory findings in survived and deceased patients with COVID-19: diagnostic role of inflammatory indications in determining the severity of illness

Background: Since December 2019, when a cluster of pneumonia cases due to SARS-CoV-2 initially emerged in Wuhan city and then rapidly spread throughout the world, the necessity for data concerning the clinical and para-clinical features of Iranian patients with COVID-19 was highlighted. Therefore, we aimed to compare the clinical, para-clinical and laboratory evidences of deceased patients with survival group. Methods: We extracted data regarding 233 patients with laboratory-confirmed COVID-19 from Buali Hospital in Iran; clinical/para-clinical and inflammatory indexes data were collected and analyzed. The data of laboratory examinations and chest CT findings were compared between deceased and survived patients. Results: The mean age of the patients was 49.8 years and 64 of our patients were male. The acute respiratory distress syndrome occurred in 64 patients, 52 who were admitted to the ICU, which all of them underwent invasive mechanical ventilation, and 28 who died. Lymphopenia (79), neutrophilia (79), and thrombocytopenia (21) were the most frequently observed laboratory findings of the deceased group on admission. Most patients (68) had a high systematic immune-inflammation (SII) index of > 500 and increased C-reactive protein level (88). Levels of inflammatory indexes such as neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and SII were documented to be significantly elevated in the deceased group when compared with the patients who survived (P < 0.0001, P < 0.001, P < 0.0001, respectively). The most commonly presented symptoms were fever (70) and cough (63) on admission. Headache was uncommon (11). Ground-glass opacity with consolidation (mixed) was the most common radiologic finding on chest CT (51). No radiographic or CT abnormality was found in 15 of 204 patients (7). Conclusion: Small fraction of patients with COVID-19 may present without fever and abnormal radiologic findings. Elevated NLR, PLR and SII can be considered as prognostic and risk stratifying factor of severe form of disease. © 2020, The Author(s)

Clinical, epidemiological, and mycological features of patients with candidemia: Experience in two tertiary referral centers in Iran

Background and purpose: Candidemia is a major cause of morbidity and mortality among patients receiving immunosuppressive therapy and those hospitalized with serious underlying diseases. Here, we investigated the epidemiological, clinical, and mycological features of candidemia in Tehran, Iran. Materials and methods: A prospective observational study of all patients diagnosed with candidemia was performed at two referral teaching hospitals in Tehran, Iran, from February to December 2018. Demographic characteristics, underlying diseases, risk factors, clinical symptoms, and laboratory analyses of candidemic patients with positive culture were mined. Candida isolates were molecularly identified by sequencing of the internal transcribed spacer region (ITS1-5.8S-ITS2). The antifungal susceptibility testing for fluconazole, itraconazole, voriconazole, posaconazole, amphotericin B, caspofungin, micafungin, and anidulafungin against the isolates was performed using CLSI broth microdilution reference method (M27-A3). Results: A total of 89 episodes were identified, with an incidence of 2.1 episodes/1000 admissions. The common underling disease were malignancy (46%), renal failure/dialysis (44%), and hypertension (40%). The overall crude mortality was 47%. C. albicans (44%) was the most frequent causative agent, followed by C. glabrata (21%), C. parapsilosis complex (15%), C. tropicalis (11%), and C. lusitaniae (3.5%). All the isolates were susceptible to amphotericin B. The activity of all four azoles was low against non-albicans Candida species, especially C. tropicalis. Conclusion: The increase in non-albicans Candida species with reduced susceptibility to antifungal drugs might be alarming in high-risk patients. Therefore, accurate knowledge of predisposing factors and epidemiological patterns in candidemia are effective steps for managing and decreasing the mortality rate in candidemia.This study has been funded and supported by Tehran University of Medical Sciences, Tehran, Iran (Grant no. 99-2-99-48944).S

Numerical resolution of the hyperbolic heat equation using smoothed mathematical functions instead of Heaviside and Dirac delta distributions

The hyperbolic bioheat equation (HBE) has been used to model heating applications involving very short power pulses. This equation includes two mathematical distributions (Heaviside and Delta) which have to be necessarily substituted for smoothed mathematical functions when the HBE is solved by numerical methods. This study focuses on which type of smoothed functions would be suitable for this purpose, i.e. those which would provide solutions similar to those obtained analytically from the original Heaviside and Delta distributions. The logistic function was considered as a substitute for the Heaviside function, while its derivative and the probabilistic Gaussian function were considered as substitutes for the Delta distribution. We also considered polynomial interpolation functions, in particular, the families of smoothed functions with continuous second derivative without overshoot used by COMSOL Multiphysics. All the smoothed functions were used to solve the HBE by the Finite Element Method (COMSOL Multiphysics), and the solutions were compared to those obtained analytically from the original Heaviside and Delta distributions. The results showed that only the COMSOL smoothed functions provide a numerical solution almost identical to the analytical one. Finally, we demonstrated mathematically that in order to find a suitable smoothed function (f) that must adequately substitute any mathematical distribution (D) in the HBE, the difference D - f must have compact support. (c) 2013 Elsevier Ltd. All rights reserved.This work received financial support from the Spanish "Plan Nacional de I + D + I del Ministerio de Ciencia e Innovacion" Grant No. TEC2011-27133-C02-01 and from Universitat Politenica de Valencia (PAID-06-11 Ref. 1988). V. Romero Garcia is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV del Campus de Excelencia (CEI-01-11)" and FEDER Project MAT2009-09438.Rivera Ortun, MJ.; Trujillo Guillen, M.; Romero García, V.; López Molina, JA.; Berjano Zanón, E. (2013). Numerical resolution of the hyperbolic heat equation using smoothed mathematical functions instead of Heaviside and Dirac delta distributions. International Communications in Heat and Mass Transfer. 46:7-12. https://doi.org/10.1016/j.icheatmasstransfer.2013.05.017S7124

COVID-19 Associated Mucormycosis::A Review of an Emergent Epidemic Fungal Infection in 3 Era of COVID-19 Pandemic

At a time when the COVID-19's second wave is still picking up in countries like India, a number of reports describe the potential association with a rise in the number of cases of mucormycosis, commonly known as the black fungus. This fungal infection has been around for centuries and affects those people whose immunity has been compromised due to severe health conditions. In this article, we provide a detailed overview of mucormycosis and discuss how COVID-19 could have caused a sudden spike in an otherwise rare disease in countries like India. The article discusses the various symptoms of the disease, class of people most vulnerable to this infection, preventive measures to avoid the disease, and various treatments that exist in clinical practice and research to manage the disease

Oropharyngeal candidiasis in hospitalised COVID-19 patients from Iran: Species identification and antifungal susceptibility pattern

Background: Emergence of coronavirus disease 2019 (COVID-19) is a major healthcare threat. Apparently, the novel coronavirus (SARS-CoV-2) is armed by special abilities to spread and dysregulate the immune mechanisms. The likelihood of oropharyngeal candidiasis (OPC) development in COVID-19 patients with a list of attributable risk factors for oral infections has not yet been investigated. Objectives: We here aim to investigate the prevalence, causative agents and antifungal susceptibility pattern of OPC in Iranian COVID-19 patients. Patients and Methods: A total of 53 hospitalised COVID-19 patients with OPC were studied. Relevant clinical data were mined. Strain identification was performed by 21-plex PCR and sequencing of the internal transcribed spacer region (ITS1-5.8S-ITS2). Antifungal susceptibility testing to fluconazole, itraconazole, voriconazole, amphotericin B, caspofungin, micafungin and anidulafungin was performed according to the CLSI broth dilution method. Results: In 53 COVID-19 patients with OPC, cardiovascular diseases (52.83) and diabetes (37.7) were the principal underlying conditions. The most common risk factor was lymphopaenia (71). In total, 65 Candida isolates causing OPC were recovered. C albicans (70.7) was the most common, followed by C glabrata (10.7), C dubliniensis (9.2), C parapsilosis sensu stricto (4.6), C tropicalis (3) and Pichia kudriavzevii (=C krusei, 1.5). Majority of the Candida isolates were susceptible to all three classes of antifungal drugs. Conclusion: Our data clarified some concerns regarding the occurrence of OPC in Iranian COVID-19 patients. Further studies should be conducted to design an appropriate prophylaxis programme and improve management of OPC in critically ill COVID-19 patients. © 2020 Blackwell Verlag Gmb