Experimental investigation of forced and mixed convection heat transfer in a foam-filled horizontal rectangular channel

An experimental study was performed to investigate the heat transfer characteristics of the mixed convection flow through a horizontal rectangular channel where open-cell metal foams of different pore densities (10, 20 and 30 PPI) were situated. A uniform heat flux was applied at all of the bounding walls of the channel. For each of three values of the uniform heat flux, temperatures were measured on the entire surfaces of the walls. Results for the average and local Nusselt numbers are presented as functions of the Reynolds and Richardson numbers. The Reynolds number based on the channel height of the rectangular channel was varied from 600 to 33000, while the Richardson number ranged from 0.02 to 103, extending over forced, mixed and natural convection. Second important parameter that influences the heat transfer is the aspect ratio of the foams. Three different aspect ratios (AR) as 0.25, 0.5 and 1 are tested. Based on the experimental data, new empirical correlations have been constructed to link the Nusselt number. The results of all cases were compared to that of the empty channel and the literature. We found that our results were in agreement with those that are mentioned in the literature.     

Three dimensional stress analysis of solid oxide fuel cell anode micro structure

One of the most common problems in solid oxide fuel cells (SOFCs) is the delamination and thus the degradation of electrode/electrolyte interface which occurs in the consequences of the stresses generated within the different layers of the cell. Nowadays, the modeling of this problem under certain conditions is one of the main issues for the researchers. The structural and thermo-physical properties of the cell materials (i.e. porosity, density, Young's modulus etc.) are usually assumed to be homogenous in the mathematical modeling of solid oxide fuel cells at macro-scale. However, during the real operation, the stresses created in the multiphase porous layers might be very different than those at macro-scale. Therefore, micro-level modeling is required for an accurate estimation of the real stresses and the performance of SOFCs. This study presents a microstructural characterization and a finite element analysis of the delamination and the degradation of porous solid oxide fuel cell anode and electrode/electrolyte interface under various operating temperatures, compressing forces and material compositions by using the synthetically generated microstructures. A multi physics computational package (COMSOL) is employed to calculate the Von Misses stresses in the anode microstructures. The maximum thermal stress in the electrode/electrolyte interface and three phase boundaries is found to exceed the yield strength at 900 °C while 800 °C is estimated as a critical temperature for the delamination and micro cracks due to thermal stress generated. The thermal stress decreases in the grain boundaries with increasing content of one of the phases (either Ni or YSZ) and the porosity of the electrode. A clamping load higher than 5 kg cm⁻² is also found to exceed the shear stress limit.     

Effects of nutrient and bioactive food components on Alzheimer's disease and epigenetic

Alzheimer's disease (AD) is the most common form of dementia in the elderly and is a chronic neurodegenerative disease that is becoming widespread. For this reason, in recent years factors affecting the development, progression and cognitive function of the AD have been emphasized. Nutrients and other bioactive nutrients are among the factors that are effective in AD. In particular, vitamins A, C and E, vitamins B₁, B₆ and B₁₂, folate, magnesium, choline, inositol, anthocyanins, isoflavones etc. nutrients and bioactive nutrients are known to be effective in the development of AD. Nutrients and nutrient components may also have an epigenetic effect on AD. At the same time, nutrients and bioactive food components slow down the progression of the disease. For this reason, the effect of nutrients and food components on AD was examined in this review.     

Aspirin-triggered 15-epi-lipoxin A4 (ATL) generation by human leukocytes and murine peritonitis exudates: development of a specific 15-epi-LXA4 ELISA

Aspirin (ASA) triggers the formation of 15-epi-lipoxins (15-epi-LXs or ATL [ASA-triggered LX]), which are potent bioactive eicosanoids that may contribute to the therapeutic impact of ASA. To elucidate the role of these new compounds in vivo, it is essential to establish quick and sensitive detection methods. To this end, we prepared an enzyme-linked immunosorbent assay specific for 15-epi-LXA4 that proved to be highly sensitive (IC50 approximately 50 pg, minimum detection approximately 3.5 pg) and stereoselective. The amounts of 15-epi-LXA4 generated by human neutrophils from peripheral blood of healthy volunteers using this enzyme-linked immunosorbent assay were in agreement with those values obtained by liquid chromatography. Formation of 15-epi-LXA4 was cell ratio-dependent during THP-1 (a monocytic leukemia cell line)-neutrophil interactions with ASA-treated cells, and 15-epi-LXA4 was not detected with either cell type alone. Generation of 15-epi-LXA4 was also examined in murine peritonitis with ASA administration. Exudates from ASA-treated mice showed increased production of 15-epi-LXA4 that was diminished by indomethacin, a blocker of ASA-dependent acetylation of prostaglandin G/H synthase. A cytochrome P450 inhibitor administered in the presence of ASA did not prevent 15-epi-LXA4 formation, which suggests that P450 does not significantly contribute to formation of 15-epi-LXA4 in this murine model. These results indicate that the new enzyme-linked immunosorbent assay is both sensitive and selective for 15-epi-LXA4 and that 15-epi-LXA4 is produced by human leukocyte-leukocyte interactions. In addition, 15-epi-LXA4 is generated by inflammatory exudates when ASA is administered during murine peritonitis and when prostaglandin G/H synthase is upregulated and acetylated. This assay should provide rapid means to investigate 15-epi-LXA4 generation in both cellular and animal models.     

The antitumour activity of the prodrug N-L-leucyl-doxorubicin and its parent compound doxorubicin in human tumour xenografts

The antitumour activity of the investigational agent N-L-leucyl-doxorubicin (Leu-DOX) was compared with that of doxorubicin (DOX) in human tumour xenografts growing subcutaneously in athymic nude mice. Leu-DOX was developed as a prodrug of DOX, and may be converted into the clinically active parent compound by hydrolytic enzymes present in or on tumour cells. It has been suggested that a better therapeutic index with a reduced cardiac toxicity and higher efficacy might be obtained. Both compounds were administered intravenously weekly for 2 weeks, each at maximum tolerated doses of 8 mg/kg and 28 mg/kg for DOX and Leu-DOX, respectively. The panel of xenografts represented three different tumour types. Leu-DOX showed antitumour activity, defined as tumour growth inhibition > 50% and specific growth delay > 1.0, in 10 of the 16 tumours, including two of five breast, five of seven small cell and three of four non-small cell lung carcinomas. In comparison, DOX was active in one breast, four small cell lung and two lung adenocarcinoma xenografts. In all the DOX sensitive lung tumours, Leu-DOX showed higher efficacy than the parent compound. Based on the results of the present study, and since phase I clinical trials with Leu-DOX have already been performed, phase II clinical evaluation of Leu-DOX in patients with breast and lung cancer is recommended.     

Arthroscopic-assisted reduction of distal radius fractures

The outcomes of seven patients with severe comminuted intraarticular fractures of the distal radius treated by arthroscopic reduction and percutaneous external fixation (ARPEF) were retrospectively reviewed. All of the fractures were classified as C3 types using the AO classification scheme. Outcomes were evaluated using the Gartland and Werley functional criteria, an objective wrist examination, a radiographic analysis, and a self-assessment outcome form at an average follow-up of 27 months (range, 12 to 45 months). All patients were free of pain and had returned to their prior occupations. No patient had articular incongruency of greater than 1 mm, and there was no evidence of radiocarpal degenerative change. Active range of motion and maximal grip strength averaged 92% and 98%, respectively, of the uninjured wrist. The technique of arthroscope-assisted reduction and percutaneous external fixation yielded excellent results in a small group of patients, with minimal complications.     

Time-dependent differential changes of immune function in rats exposed to chronic intermittent noise

Noise is a highly relevant environmental and clinical stressor. Compared to most other experimental stressors, noise is a modest activator of neuroendocrine pathways that mimic the situation in human health where neuroendocrine activation by environmental stressors is often absent or difficult to establish. Little is known about the effects of noise exposure on the immune system. In the present work, the effects of a low-intensity chronic intermittent unpredictable noise regimen on various parameters of immune function was studied. Male wistar rats were exposed to a randomized noise protocol (white noise, 85 dB, 2-20 kHz) for 10 h per day, 15 min per h over a total period of 3 weeks. Control animals were exposed to ambient sound only. Immune function was monitored after 24 h, 7 days, and 21 days of noise exposure. Noise induced several significant changes in immune function in a time-dependent differential pattern involving both immunosuppression and immunoenhancement. After 24 h, serum IgM levels were increased and peripheral phagocytic activity was decreased. Splenic lymphocytic proliferation to mitogens was significantly decreased after 7 days, but slightly elevated after 3 weeks. The activity of splenic NK cells was increased significantly after 24 h and 7 days, but suppressed after 3 weeks. These results show that various parameters of immune function are affected differentially over time in a period of chronic mild noise stress, possibly due to sequential activation of different physiological mechanisms.     

The side chains responsible for the dimerization of the estradiol receptor by ionic bonds are lost in a 17 kDa fragment extending downstream from aa 303

Fragments of 32, 26 and 17 kDa of the porcine estradiol receptor were prepared, all of which contain the ligand-binding site. While dimers of the 32 and 26 kDa fragments like those of intact receptor can be dissociated by protonation, the dimer of the 17 kDa fragment obtained by trypsination of the 26 kDa fragment is resistant to lowering the pH from 7.0 to 6.5 and below. Its dissociation can be achieved by 0.5 M MgCl2 at pH 7.0. All fragments are recognized by the MAB 13H2 in Western blots. The antibody also reacts with native receptor and the three fragments, both in their monomer and dimer states. The combining ratios of antibody with receptor, or its fragments, in the monomer and dimer states and the weakening of the estradiol-receptor bond by antibody attachment support the back to back and head to toe model of receptor dimers.