2-D Non-Fickian Dispersion Model for the Initial Period of River Mixing

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Two dimensional analysis of flow patterns and dispersion in meandering channels

River hydrodynamicsTurbulent open channel flow and transport phenomen

A Particle Dispersion Model For Analysis Of Two-Dimensional Mixing In Open Channels

Pollutant mixing in natural rivers is analyzed by using the two-dimensional depth-averaged advection-dispersion model (2D ADE) for rapid completion of the vertical mixing. The dispersion term in the 2D ADE follows Taylor’s assumption (Taylor, 1954; Fischer et al., 1979) which can be applied in the Taylor period. However, most open channel flow has long initial period which makes the skewed concentration distribution due to the unbalance between the shear flow advection and the vertical mixing (Chatwin, 1970). Therefore, the non-Fickian dispersion model is necessary to compensate the limitations of the 2D ADE model. In this research, the two-dimensional particle dispersion model (2D PDM) was developed to analyze the pollutant mixing both in the initial and the Taylor period without determination of the dispersion coefficient. In the 2D PDM, pollutant particles were introduced to visualize physical mixing process according to the complicate flow variation in open channels. The 2D PDM is based on the shear flow dispersion theory and adopted the operator split method which divides the shear advection stage and the turbulent diffusion stage. In the shear advection stage, particles were separated by the vertical velocity deviations in the longitudinal and transverse directions. The separated particles according to the shear flow were mixed across the vertical in the turbulent diffusion stage. After the particle mixing, the particle distribution in each time step was converted to the concentration field for various analysis. The 2D PDM was applied to the straight channel and the meandering channel for analysis of the conservative pollutant mixing. In the straight channel, concentration curves from the 2D PDM showed skewed distribution in the initial period and then turned into the Gaussian distribution in the Taylor period. And, the concentration distributions in the meandering channel showed good agreement with the tracer test results

Numerical Analysis of Flow Characteristics in Confulent Channels

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Reconstructive challenge of dermatofibrosarcoma protuberans in the female breast

Dermatofibrosarcoma protuberans is an uncommon locally aggressive malignant neoplasm that most frequently appears in the trunk, followed by the extremities, head, and neck. But occurrence in the breast is extremely rare. We present a case of a 28-year-old woman, who had a history of trauma 5 years previously and excision 1 year before presentation at our clinic. We performed wide excision, together with microscopic and immunohistochemical analysis. No postoperative oncologic treatment was used and she remains disease-free 1 year after the surgery without any tumor recurrence. Here, we report a case of dermatofibrosarcoma protuberans in the female breast and present a detailed discussion of the diagnosis and treatment with reference to available literatures

Anti-malarial activity of 6-(8'Z-pentadecenyl)-salicylic acid from Viola websteri in mice

<p>Abstract</p> <p>Background</p> <p>Petroleum ether extracts of <it>Viola websteri </it>Hemsl (Violaceae) were reported to have anti-plasmodial activity against <it>Plasmodium falciparum in vitro</it>, with this activity being largely attributable to 6-(8'Z-pentadecenyl)-salicylic acid (6-SA).</p> <p>Methods</p> <p>The schizontocidal activity of 6-SA on early <it>Plasmodium berghei </it>infections was evaluated in a four-day test. The possible 'repository' activity of 6-SA was assessed using the method described by Peters. The median lethal dose (LD₅₀) of 6-SA, when given intraperitoneally, was also determined using uninfected ICR mice and the method of Lorke.</p> <p>Results</p> <p>In the present study, 6-SA was found to have anti-malarial activity <it>in vivo</it>, when tested against <it>P. berghei </it>in mice. 6-SA at 5, 10 and 25 mg/kg·day exhibited a significant blood schizontocidal activity in four-day early infections, repository evaluations and established infections with a significant mean survival time comparable to that of the standard drug, chloroquine (5 mg/kg·day).</p> <p>Conclusion</p> <p>6-SA possesses a moderate anti-malarial activity that could be exploited for malaria therapy.</p

Estimating baseline creatinine values to define acute kidney injury in critically ill pediatric patients

Background Acute kidney injury (AKI) is a common complication in critically ill children. However, the common lack of baseline serum creatinine values affects AKI diagnosis and staging. Several approaches for estimating baseline creatinine values in those patients were evaluated. Methods This single-center retrospective study enrolled pediatric patients with documented serum creatinine measurements within 3 months before admission and more than two serum creatinine measurements within 7 days after admission to the pediatric intensive care unit of a tertiary care children’s hospital between January 2016 and April 2020. Four different approaches for estimating AKI using serum creatinine measurements were compared: 1) back-calculation using age-adjusted normal reference glomerular filtration rates, 2) age-adjusted normal reference serum creatinine values, 3) minimum values measured within 7 days after admission, and 4) initial values upon admission. Results The approach using minimum values showed the best agreement with the measured baseline value, with the largest intraclass correlation coefficient (0.623), smallest bias (–0.04), and narrowest limit of agreement interval (1.032). For AKI diagnosis and staging, the minimum values were 80.8% and 76.1% accurate, respectively. The other estimated baseline values underestimated AKI and showed poor agreement with baseline values before admission, with a misclassification rate of up to 42% (p < 0.001). Conclusion Minimum values of serum creatinine measured within 7 days after hospital admission showed the best agreement with creatinine measured within 3 months before admission, indicating the possibility of using it as a baseline when baseline data are unavailable. Further large-scale studies are required to accurately diagnose AKI in critically ill children