Oscillatory Flow Mechanism for Enhanced Heat Transfer

This research project is about the use of an oscillatory flow mechanism to enhance heat transfer. The idea behind this is to induce oscillation of the end wall of one of two connected chambers of a heat exchanger which effectively will induce oscillation of the boundary layer within the connecting duct. The main idea of this thesis came from using species separation studies before 40 years ago in hyperventilation technology to help patients under anesthesia in hospitals. There are many applications for this research such as removing heat from chemical reactors, electrical devices and other enclosed environments such as submarines, underground facilities and so forth. Many parameters can be varied to maximize the convective heat transfer. These parameters include the amplitude and frequency of oscillation, as well as duct radius and length. In this thesis, results from three-dimensional time-accurate studies carried out using computational fluid dynamics are presented. These results simulate the diffusion and convection of energy in air. The model consists of two chambers with inlets at two different temperatures, an oscillating piston wall on one of the chambers, and a connecting tube. Several cases are carried out reporting on heat transfer enhancement as a function of the tidal displacement to connecting tube diameter. Unlike previous studies which were undertaken using asymptotic analysis, the present models and results incorporate full entrance effects and 3D interactions. Results of this study will be useful as a guide for the design and miniaturization of an oscillating device for enhanced heat transfer in further research projects. Simulations were performed to analyze the effect of oscillations on the heat transfer. A simulation was first carried out in steady-state to serve as the baseline for comparison with time-accurate oscillating results. The remaining simulations consist of altering the frequency and tidal displacement of the moving wall to analyze their effect on the heat transfer between the two chambers. The results suggest that the heat transfer is enhanced as a function of the frequency and tidal displacement of the moving wall and that there should be an optimal point. Results are presented in the form of contour and vector plots of the temperature and velocity fields as well as plots of the heat exchanger outlet temperatures as a function of frequency and displacement

A Review of Patients with Renal Disease Undergoing Vascular Access Surgery: Is Gray-scale Ultrasound Enough?

Background An adequate fistula or graft is essential to long-term survival and quality of life for patients with end-stage renal disease (ESRD) who are receiving hemodialysis because of its lower complication rates, lower costs, and prolonged patency. Use of duplex ultrasound for preoperative planning is currently recommended by the Kidney Disease Outcomes Quality Initiative for patients with ESRD with prior fistulas or grafts, central lines, pacemakers, and prior chest or arm surgery. The preoperative evaluation consisted of gray-scale ultrasound and physical examination in all patients with ESRD in this study. The current study determined the baseline data, including the type of vascular access, functional patency of access, associated morbidity, and preoperative demographics and comorbidities, including prior dialysis access. The primary objective was to determine the frequency of revision surgery, to identify the potential cases that may indicate the need for better assessments (eg, duplex ultrasound), and to improve fistula and graft success rates. Materials and methods A retrospective chart review of patients with ESRD who underwent native fistula or graft access creation in a 13-month time period from 2010 to 2011 was completed. Seventy-six surgical procedures were performed on 53 subjects. Included variables were age, race, gender, smoking status, body mass index, stage of chronic kidney disease at referral, previous central lines/pacemakers, fistulas, or grafts. Comorbidities identified included diabetes mellitus (DM), hypertension (HTN), and coronary artery disease (CAD). The types of access, location, maturation, infection, failure, or revision were noted. Continuous variables are shown in frequencies and mean. Categoric data were compared using chi-square analysis. Results During the 13-month study period, 76 surgical procedures were performed in 53 patients, with 39.6% of patients undergoing multiple surgical procedures. The majority of patients were male (98%) and white (58.5%), with a history of HTN (96.2%) and DM (64.2%). The mean age was 68 years, with most patients presenting in stage 5 chronic kidney disease (92.5%). Some 67.9% of patients had prior central lines or pacemakers; of those, 56.6% had previous fistulas or grafts. Negative significance was determined between the comorbidities DM/HTN/CAD alone or grouped as a cohort and multiple surgeries. Positive significance was found between multiple surgical procedures and those with prior access/ pacemaker/central line (chi-square [1, N = 53] = exact P = .04). Conclusions Patients with ESRD undergoing access creation presenting with prior central lines, pacemakers, or arm surgery (fistulas or grafts) were more likely to undergo multiple surgeries to obtain a functional graft or fistula for hemodialysis use than those patients with ESRD without prior central lines, pacemakers, or arm surgery (fistulas or grafts). Color duplex ultrasound should be considered as a standard for preoperative assessment in an effort to improve fistula or graft success rates

Peranan promosi dan publisiti membantu dalam menarik minat audien untuk menonton sebuah pementasan kajian kes : Bukan Bunuh Diri karya Dinsman

Untuk mencapai bilangan audein yang disasarkan dalam pementasan sesebuah produksi teater, promosi dan publisiti yang berterusan sehingga hari yang terakhir pemetnasan teater. Ini meliputi pemilihan kain rentang, iklan, kenyataan akhbar, poster dan sebagainya memainkan peranan yang amat penting kerana ianya dapat menarik minat sasaran audien terhadap pementasan ini yang akhirnya menentukan bilangan audien yang menyaksikan produksi teater berkenaan

Arsenosugar phospholipids and arsenic hydrocarbons in two species of brown macroalgae

Fourteen arsenolipids, including 11 new compounds, were identified and quantified in two species of brown algae, Wakame (Undaria pinnatifida) and Hijiki (Hizikia fusiformis), by high resolution mass spectrometry, high performance liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry. Both algal species contained arsenosugar-phospholipids as the major type of arsenolipid, and arsenic-hydrocarbons were also significant components, particularly in Hijiki. The origin of the various arsenolipids, and the possible significance of their relative quantities, is briefly discussed

Determination of water and lipid-soluble arsenic compounds in the commercial edible seaweed Hijiki (Hizikia fusiforme)

Se presentan los resultados obtenidos en los estudios de especiación de arsénico realizados sobre el alga comestible Hijiki. Los análisis se realizaron a través de métodos analíticos desarrollados en la UPM (España) y en la Universidad de Graz (Austria). La determinación de especies hidrosolubles se realizó mediante HPLC-(UV)-HG-AFS, previa extracción mediante MAE con agua desionizada. Por otro lado, la identificación y cuantificación de arsenolípidos se llevó a cabo mediante HPLC-ICPMS/ESMS, previa extracción con cloroformo:metanol y purificación mediante SPE

Rituximab efficacy in pediatric patients with refractory nephrotic syndrome

Background: Nephrotic syndrome (NS) in children is a disease of glomerular filtration barrier failure, manifesting with severe proteinuria leading to hypoalbuminemia, hypercholesterolemia, and generalized edema. it could be primary or secondary. In primary NS, also known as idiopathic NS, the histological findings of Primary NS include minimal change disease which mainly respond to steroids (steroid sensitive NS), focal segmental glomerulosclerosis which are usually steroid resistant or membranous nephropathy. Rituximab has been shown to be effective for patients with complicated FRNS/SDNS and refractory SRNS. While the incidence of nephrotic syndrome (NS) is increasing, the morbidity of difficult-to-treat NS is significant.Methods: This is a retrospective cohort study that took place in King Abdulaziz University Hospital from 2012 to 2016. Patients included: Any patient under 18 years, and diagnosed with steroid resistant and dependent nephrotic syndrome. Patients excluded: Any patient above 18 years, and known to have secondary Nephrotic Syndrome.Results: Present study consists of 24 children with nephrotic syndrome (NS) were recruited in the study. In the population 8 patients (33.33 %) were diagnosed with SDNS, while the other 16 patients (66.67%) were diagnosed SRNS. Also, patients who were treated with Rituximab we found that (the mean) number of relapses per year before rituximab was about 2.67±1.49 (standard deviation 1.49), while patient who relapsed after rituximab was about 1.09±1.38 (standard deviation 1.38).Conclusions: Rituximab is a biological agent that started to be widely used in difficult nephrotic syndrome cases. The effectiveness of rituximab is most observed in steroid depended nephrotic syndrome patients since it decreases the frequency of relapses and steroid dependency. However, it has been shown that it is less effective in steroid resistant nephrotic syndrome cases and was associated with significant numbers of relapses

The flavonoid 4,4′-dimethoxychalcone promotes autophagy-dependent longevity across species

Ageing constitutes the most important risk factor for all major chronic ailments, including malignant, cardiovascular and neurodegenerative diseases. However, behavioural and pharmacological interventions with feasible potential to promote health upon ageing remain rare. Here we report the identification of the flavonoid 4,4′- dimethoxychalcone (DMC) as a natural compound with anti-ageing properties. External DMC administration extends the lifespan of yeast, worms and flies, decelerates senescence of human cell cultures, and protects mice from prolonged myocardial ischaemia. Concomitantly, DMC induces autophagy, which is essential for its cytoprotective effects from yeast to mice. This pro-autophagic response induces a conserved systemic change in metabolism, operates independently of TORC1 signalling and depends on specific GATA transcription factors. Notably, we identify DMC in the plant Angelica keiskei koidzumi, to which longevity- and health-promoting effects are ascribed in Asian traditional medicine. In summary, we have identified and mechanistically characterised the conserved longevity-promoting effects of a natural anti-ageing drug

eotransform-xarray

The eotransform-xarray package provides common transformations on raster data represented as xarray) data structures, following the Transformer protocol of eotransform.If you use this software, please cite it using the metadata from this file