Experimental and analytical performance investigation of air to air two phase closed thermosyphon based heat exchangers

In recent years, the use of wickless heat pipes (thermosyphons) in heat exchangers has been on the rise, particularly in gas to gas heat recovery applications due to their reliability and the level of contingency they offer compared to conventional heat exchangers. Recent technological advances in the manufacturing processes and production of gravity assisted heat pipes (thermosyphons) have resulted in significant improvements in both quality and cost of industrial heat pipe heat exchangers. This in turn has broadened the potential for their usage in industrial waste heat recovery applications. In this paper, a tool to predict the performance of an air to air thermosyphon based heat exchanger using the ε-NTU method is explored. This tool allows the predetermination of variables such as the overall heat transfer coefficient, effectiveness, pressure drop and heat exchanger duty according to the flow characteristics and the thermosyphons configuration within the heat exchanger. The new tool's predictions were validated experimentally and a good correlation between the theoretical predictions and the experimental data, was observed. © 2014 Elsevier Ltd. All rights reserved

On-board demux/demod

To make satellite channels cost competitive with optical cables, the use of small, inexpensive earth stations with reduced antenna size and high powered amplifier (HPA) power will be needed. This will necessitate the use of high e.i.r.p. and gain-to-noise temperature ratio (G/T) multibeam satellites. For a multibeam satellite, onboard switching is required in order to maintain the needed connectivity between beams. This switching function can be realized by either an receive frequency (RF) or a baseband unit. The baseband switching approach has the additional advantage of decoupling the up-link and down-link, thus enabling rate and format conversion as well as improving the link performance. A baseband switching satellite requires the demultiplexing and demodulation of the up-link carriers before they can be switched to their assigned down-link beams. Principles of operation, design and implementation issues of such an onboard demultiplexer/demodulator (bulk demodulator) that was recently built at COMSAT Labs. are discussed

IgA-dominant post-infectious glomerulonephritis presenting as a fatal pulmonary-renal syndrome

Over the last decades, post-infectious glomerulonephritis underwent major changes in its epidemiology, pathophysiology, and outcomes. We are reporting a case of IgA-dominant post-infectious glomerulonephritis (IgA-PIGN) presenting as a fatal pulmonary-renal syndrome. An 86-year-old Filipino man presented with worsening dyspnea, hemoptysis, and decreased urine output over 2 weeks. Past medical history is significant for hypertension, chronic kidney disease stage III, and pneumonia 3 weeks prior treated with intravenous cefazolin for methicillin-sensitive Staphylococcus aureus bacteremia. Physical examination was remarkable for heart rate of 109/min and respiratory rate of 25/min saturating 99% on 3 liters via nasal cannula. There were bibasilar rales in the lungs and bilateral ankle edema. A chest radiograph showed bibasilar opacifications. Blood work was significant for hemoglobin of 8.3 g/dL and creatinine of 9.2 mg/dL (baseline of 1.67). TTE showed EF 55%. Urinalysis revealed large blood and red blood cell casts. Kidney ultrasound showed bilateral echogenicity compatible with renal disease. Pulse methylprednisolone therapy and hemodialysis were initiated with patient\u27s condition precluding kidney biopsy. Serology workup for rapidly progressive glomerulonephritis was negative. On day 7, the patient required mechanical ventilation; bronchoscopy showed alveolar hemorrhage and plasmapheresis was initiated. Renal biopsy revealed IgA-PIGN with endocapillary and focal extracapillary proliferative and exudative features. IgA-PIGN occurs in diabetic elderly (mean age of 60 years), 0-16 weeks after an infection mainly by Staphylococcus. However, this nondiabetic patient had normal complement IgA-PIGN with fatal pulmonary-renal syndrome. Understanding the pathogenesis and identifying the nephrotoxic bacteria species and the aberrant IgA molecule will open new insights toward prevention and treatment

Maximum Radiated Emissions of Printed Circuit Board Using Analytical Methods

The rapid progress of technology has imposed significant challenges on Printed Circuit Boards (PCB) designers. Once of those challenges is to satisfy the electromagnetic compatibility (EMC) compliance requirements. For that reason, EMC compliance must be considered earlier at the design stage for time and cost savings. Conventionally, full wave simulation is employed to check whether the designed PCB meets EMC standards or not. However, this method is not a suitable option since it requires intensive computational time and thus increasing the unit cost. This paper describes novel analytical models for estimating the radiated emissions (RE) of PCB. These models can be used to help the circuit designer to modify their circuit based on the maximum allowable RE comparing to the relevant EMC-RE standard limit. Although there are many RE sources on PCB, this paper focuses on the significant source of RE on PCB; namely PCB-traces. The trace geometry, termination impedance, dielectric type, etc. can be specified based on the maximum allowable emissions. The proposed models were verified by comparing the results of the proposed models with both simulation and experimental results. Good agreements were obtained between the analytically computed results and simulation/measurement results with accuracy of ±3dB

Sitting time and risk of cardiovascular disease and diabetes: a systematic review and meta-analysis

Context: Whether physical activity attenuates the association of total daily sitting time with cardiovascular disease (CVD) and diabetes incidence is unclear. This systematic review and meta-analysis examined the association of total daily sitting time with CVD and diabetes with and without adjustment for physical activity. Evidence Acquisition: PubMed, Web of Science, BASE, MEDLINE, Academic Search Elite and ScienceDirect were searched for prospective studies published between 1st January 1989 and 15th February 2019 examining the association of total daily sitting time with CVD or diabetes outcomes. Data extraction and  study quality assessments were conducted by two independent reviewers. Pooled Hazard Ratios (HRs) were calculated using a fixed-effects model. The quality assessment and meta-analytic procedures were completed in 2018. Evidence Synthesis: Nine studies with 448,285 40 participants were included. Higher total daily sitting time was associated with a significantly increased risk of CVD (HR 1.29; 95%CI 1.27-1.30, p=<0.001) and diabetes (HR 1.13; 95%CI 1.04-1.22, p=<0.001) incidence when physical activity was not adjusted for. The increased risk for diabetes was unaffected when adjusting for physical activity (HR 1.11;  95%CI 1.01-1.19, p=<0.001). For CVD, the increased risk was attenuated but remained significant (HR 1.14; 95%CI 1.04-1.23, p=<0.001). Conclusions: Higher levels of total daily sitting time are associated with an increased risk of CVD and diabetes, independent of physical activity. Reductions in total daily sitting may thus be recommended in public health guidelines

Heat-induced changes in soil water-extractable organic matter characterized using fluorescence and FTIR spectroscopies coupled with dimensionality reduction methods

[Abstract:] Water extractable organic matter (WEOM) is a very mobile and reactive soil OM fraction, critical in the translocation of carbon (C) from soils to other environmental compartments. Transformations of WEOM due to soil heating can have implications not only at a local scale, but in places far away from the location of the event. However, their accurate characterization is costly when analyzing a large number of samples. The objectives of this work were to identify common patterns for the changes in WEOM caused by the heating of various soil types using a combination of spectroscopic and dimensionality reduction techniques. Six soils from Spain, Kenya and Israel were collected at depths 0–10 cm and analysed before and after heating in air to temperatures of 300 and 600 °C. Fluorescence EEMs were measured in soil–water extracts containing WEOM, and decomposed using parallel factor (PARAFAC) analysis. The FTIR spectra were measured in freeze-dried extracts and further analysed using non-negative matrix factorization (NMF). Total organic C and SUVA254 values of the extracts experienced changes with the heating treatments that were soil dependant. Four PARAFAC and three NMF components were sufficient to characterize WEOM changes in all soils, which showed common thermal transformation patterns irrespective of their origin and properties. Thermal transformation of fluorescent WEOM led to the increase in the proportion of a component with an emission maximum at Ex 300/Em 392 nm, and to a lower extent one with the emission maximum at Ex 300/Em 426 nm. Concomitantly, the proportion of components with emission maxima at longer excitation wavelengths was reduced. These changes occurred at the lowest heating temperature and were maintained at 600 °C, and they seem to indicate a depletion of fluorescent components more conjugated, bigger in size, and an enrichment in smaller ones. The NMF components obtained from FTIR spectra showed an increase of the proportion of compounds with Csingle bondO bonds, more oxidized. No correlations were found between the components obtained with each method, thus indicating that the information obtained from the fluorescence EEMs-PARAFAC analysis and the NMF decomposition of FTIR spectra is complementary. It can be concluded that there is a common pattern of WEOM changes induced by thermal soil transformations irrespective of the origin and properties of the soils studied, and that the combination of different spectroscopic techniques coupled with dimensionality reduction methods can be used as a simple and low-cost method to fingerprint changes in WEOM composition, in general, and those caused by soil heating, in particular

An Overlapping Case of Lupus Nephritis and IgG4-Related Kidney Disease

We report a case of a 71-year-old Filipino female who was admitted to the hospital for abdominal pain, vomiting and diarrhea of 8 days duration. The patient was found to have marked acute kidney injury (AKI), which required hemodialysis in the next 3 days. Extensive workup revealed hematuria, subnephrotic range proteinuria, elevated anti-nuclear antibody (ANA) and elevated total immunoglobulin G (IgG) levels, with normal IgG4 and anti-dsDNA levels. On kidney biopsy, mild membranous glomerulonephritis was found, along with autoimmune tubulointerstitial nephritis (TIN) with a full-house pattern of immune deposits. These findings were suggestive of lupus interstitial nephritis. However, IgG4+ plasma cells were detected in the interstitium by immunostaining, favoring a diagnosis of IgG4-related kidney disease (IgG4-RKD). Our case highlights the difficulty in differentiating lupus nephritis (LN) from IgG4-RKD in some patients, raising the suspicion that these two entities can co-exist