Numerical Modeling of Turbulent Combustion

The work in numerical modeling is focused on the use of the random vortex method to treat turbulent flow fields associated with combustion while flame fronts are considered as interfaces between reactants and products, propagating with the flow and at the same time advancing in the direction normal to themselves at a prescribed burning speed. The latter is associated with the generation of specific volume (the flame front acting, in effect, as the locus of volumetric sources) to account for the expansion of the flow field due to the exothermicity of the combustion process. The model was applied to the flow in a channel equipped with a rearward facing step. The results obtained revealed the mechanism of the formation of large scale turbulent structure in the wake of the step, while it showed the flame to stabilize on the outer edges of these eddies

Modeling Interface Motion Of Combustion (MINOC). A computer code for two-dimensional, unsteady turbulent combustion

A computer code for calculating the flow field and flame propagation in a turbulent combustion tunnel is described. The model used in the analysis is the random vortex model, which allows the turbulent field to evolve as a fundamental solution to the Navier-Stokes equations without averaging or closure modeling. The program was used to study the flow field in a model combustor, formed by a rearward-facing step in a channel, in terms of the vorticity field, the turbulent shear stresses, the flame contours, and the concentration field. Results for the vorticity field reveal the formation of large-scale eddy structures in the turbulent flow downstream from the step. The concentration field contours indicate that most burning occurred around the outer edges of the large eddies of the shear layer

Predictors of unfavourable early outcome following Fontan completion

Background Although the magnificent improvement in Fontan operation results in the last two decades, there are still some concerns regarding the unfavourable early outcomes that may follow Fontan completion. Methods From 2003 to 2016, 79 Patients underwent Fontan operation at IRCCS Policlinico San Donato. Unfavourable early outcome was defined by the presence of one or more of these occurrences: prolonged hospital stay >25 days, Prolonged pleural effusion 6514 days and Prolonged inotropic support 6572\u202fh. Univariable and multivariable analyses were performed to detect the risk factors associated with early unfavourable outcome after Fontan completion. Results Prolonged hospital stay >25 days was found in 24.05% of patients and its associated significant risk factors were low preoperative O2 saturation (p 0.007), Fontan fenestration (p 0.009) and plasma transfusion (p 0.030). Prolonged pleural effusion 6514 days was found in 24.05% and no significant risk factors were detected. Prolonged inotropic support 6572\u202fh was found in 35.44% and significant risk factors were prolonged cardiopulmonary bypass time (P 0.003), fenestration (P 0.023), plasma transfusion (P 0.028) and non staged Fontan (P 0.039). In multivariable analysis of combined unfavourable outcome, significant risk factors were fenestration (P 0.030) with some trends towards low preoperative O2 saturation (P 0.056). Conclusion Unfavourable early outcome can occur following Fontan completion with associated prolonged hospital stay. Risk factors include low preoperative O2 saturation, prolonged cardiopulmonary bypass time, Fontan fenestration, Plasma transfusion and non staged Fontan

Irradiation embrittlement of pressure vessel steels : analysis of IAEA coordinated programme results

The results of the IAEA "Coordinated Research Programme on Irradiation Embrittlement of Pressure Vessel Steels" were examined again to analyse the reasons behind the reported large scattering and discrepancies in the effect of irradiation on the ductile-brittle transition temperature (DBTT). It is concluded that using specimens from different locations throughout the HSST steel plate thickness was the main reason behind the scattering in these results. Specimens from different locations bad different microstructures and different initial mechanical properties which led to different irradiation sensitivities. The analysis showed that the specimens used can be considered to consist of two sets different in microstructure, mechanical properties and irradiation sensitivity. Set 1 composed of specimens taken from positions between $\frac{T}{4}$ and $\frac{T}{2}$throughout the plate thickness while set 2 composed ofspecimens taken from positions between the surface and $\frac{T}{4}$.In this way the scattering became very small and evennegligable and the discrepancies were explained

Hyperechogenic renal parenchyma in potential live related kidney donors: Does it justify exclusion?

The aim of this work is to asses theimportance of ultrasonic grade I echogenicity inpotential kidney donors in the absence of urinaryabnormality and with perfect renal function.Thirty four living related kidney donors with thisabnormality were included, age range between 23-48years. Ten matched healthy donors were studied ascontrols.All cases were thoroughly investigated includingmeasuring GFR by isotopic scan and estimation ofrenal reserve by dopamine and aminoacid infusion.Renal biopsy was done for 17 cases of theechogenicity group and 8 controls. Our resultsshowed that the renal reserve was comparable in bothgroups. Glomerular changes were found in 41% ofapparently normal donors and only one case ofcontrols.Conclusion: Grade I echogenicity may be sign ofunrecognised kidney disease. Renal biopsy ismandatory when such related donors are the onlyavailable

Avascular bone necrosis of the femoral head after renal transplantation: Is it avoidable?

Background: Avascular osteonecrosis (AVN) is a seriousosseous complication after renal transplantation (RT). Itsprevalence clearly decreased from 20% to 4% possiblydue to the use of calcinurin inhibitors (CNI), reduction ofsteroid doses and use of steroid free regimens. The aimof our study was to evaluate the frequency of AVNamong our kidney transplant recipients and to determinethe risk factors for its occurrence.Patients and methods: Among 1785 kidney transplantrecipients who received renal allografts between March1976 and December 2005, 40 patients (2.24%) developedAVN with a mean age of 31.3 10.2 years. Eightykidney transplant recipients without AVN were selectedto be a matched control group. The localization of AVNwas the femoral head in all cases.Results: AVN was diagnosed at a mean of 20.4 monthsafter transplantation. The following risk factors werestatistically significant; sirolimus-based regimen,hypercholesterolemia, overweight with body mass index(BMI)>26 and those with HLA A9, HLA B35 and DRB15.Conclusions: We concluded that the proper managementof hypercholesterolemia, maintenance of ideal bodyweight as well as avoidance of sirolimus-basedimmunosuppressive regimen in genetically predisposedpatients may be an effective preventive strategy to avoidAVN

Texture analysis of MR images of patients with Mild Traumatic Brain Injury

<p>Abstract</p> <p>Background</p> <p>Our objective was to study the effect of trauma on texture features in cerebral tissue in mild traumatic brain injury (MTBI). Our hypothesis was that a mild trauma may cause microstructural changes, which are not necessarily perceptible by visual inspection but could be detected with texture analysis (TA).</p> <p>Methods</p> <p>We imaged 42 MTBI patients by using 1.5 T MRI within three weeks of onset of trauma. TA was performed on the area of mesencephalon, cerebral white matter at the levels of mesencephalon, corona radiata and centrum semiovale and in different segments of corpus callosum (CC) which have been found to be sensitive to damage. The same procedure was carried out on a control group of ten healthy volunteers. Patients' TA data was compared with the TA results of the control group comparing the amount of statistically significantly differing TA parameters between the left and right sides of the cerebral tissue and comparing the most discriminative parameters.</p> <p>Results</p> <p>There were statistically significant differences especially in several co-occurrence and run-length matrix based parameters between left and right side in the area of mesencephalon, in cerebral white matter at the level of corona radiata and in the segments of CC in patients. Considerably less difference was observed in the healthy controls.</p> <p>Conclusions</p> <p>TA revealed significant changes in texture parameters of cerebral tissue between hemispheres and CC segments in TBI patients. TA may serve as a novel additional tool for detecting the conventionally invisible changes in cerebral tissue in MTBI and help the clinicians to make an early diagnosis.</p

Exogenously applied ZnO nanoparticles induced salt tolerance in potentially high yielding modern wheat (Triticum aestivum L.) cultivars

Salinity stress is one of the potential threats that adversely affect the productivity of many cereal crops worldwide. Spraying plants with nano-Zn particles may lessen effectively such negative impacts on plants; yet its mode of action is still not well explored. This study was performed to evaluate the effects of spraying nano-Zn particles with varying concentrations (0, 20, 50 and 80 mg L-1) on two wheat cultivars irrigated with saline water (EC = 6.3 dS m-1) versus a non-saline one. The key results revealed that root and shoot weights decreased significantly under salinity stress conditions, while improved considerably with nano-Zn-particles foliar application up to 50 mg nanoZn L-1; thereafter significant reductions occurred. Also, shoot and root lengths as well as plant leaf area index improved considerably owing to this foliar application. Clearly, roots and shoots weights of wheat plants sprayed with nano-Zn particles under salinity stress conditions exhibited higher values than the corresponding ones that was grown under non-saline conditions without nano-Zn-particles applications. Unexpectedly, this foliar spray led to significant reductions in plant pigments and also in enzymatic and non-enzymatic antioxidants in plants. Yet, this foliar spray enhanced formation of total soluble sugars and proline, and raised significantly Ca contents in wheat roots and shoots, and to some extent K contents. In conclusion, the foliar application of nano-Zn particles increased plant growth under salty stress conditions via two parallel processes, i.e., stimulating formation of osmolytes and stimulating nutrient uptake which may, in turn, increase plant metabolism. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CCPeer reviewe

Lipid nanocarriers overlaid with chitosan for brain delivery of berberine via the nasal route

This research aimed to design, optimize, and evaluate berberine-laden nanostructured lipid carriers overlaid with chitosan (BER-CTS-NLCs) for efficient brain delivery via the intranasal route. The nanostructured lipid carriers containing berberine (BER-NLCs) were formulated via hot homogenization and ultrasonication strategy and optimized for the influence of a variety of causal variables, including the amount of glycerol monostearate (solid lipid), poloxamer 407 (surfactant) concentration, and oleic acid (liquid lipid) amount, on size of the particles, entrapment, and the total drug release after 24 h. The optimal BER-NLCs formulation was then coated with chitosan. Their diameter, in vitro release, surface charge, morphology, ex vivo permeability, pH, histological, and in vivo (pharmacokinetics and brain uptake) parameters were estimated. BER-CTS-NLCs had a size of 180.9 ± 4.3 nm, sustained-release properties, positive surface charge of 36.8 mV, and augmented ex-vivo permeation via nasal mucosa. The histopathological assessment revealed that the BER-CTS-NLCs system is safe for nasal delivery. Pharmacokinetic and brain accumulation experiments showed that animals treated intranasally with BER-CTS-NLCs had substantially greater drug levels in the brain. The ratios of BER brain/blood levels at 30 min, AUCbrain/AUCblood, drug transport percentage, and drug targeting efficiency for BER-CTS-NLCs (IN) were higher compared to BER solution (IN), suggesting enhanced brain targeting. The optimized nanoparticulate system is speculated to be a successful approach for boosting the effect of BER in treating CNS diseases, such as Alzheimer’s disease, through intranasal therapy