Methodology for the objective and rapid determination of the performance criteria of an NH3-NaSCN absorption refrigeration system.

This work is a computer-aided methodological description for the rapid and objective analysis of the performance criteria of an absorption refrigerator. It can be used as a tool for a simulation platform to improve the parameters for the optimal operation of the present system. Sometimes, some of the obstacles of the original method related to the analysis of the performance criteria of absorption machines may come from the number of equations and the complexity of the calculation of NH3 mass fraction of NH3-NaSCN solution. The method consists of a characteristic matrix that allows to quickly determine the NH3 mass fraction of NH3-NaSCN solution in relation to the performance criteria: COP (coefficient of performance), ECOP (exergetic efficiency) and CR (circulation ratio).This could facilitate the algorithm and the direct calculation of NH3 mass fraction of NH3-NaSCN solution in contrast to the original model. For this reason, an easily reproducible flow chart has been proposed.•Transformation of complex mathematical models into easy to code models.•Elaboration of a characteristic matrix for the determination of concentrations.•Development of a platform for the simulation of performance criteria.

Geographical mapping and modelling of noise pollution from industrial motors: a case study of the Mbalmayo Thermal Power Plant in Cameroon.

To be able to geographically map, model and evaluate noisy sound emissions from industrial motors, emphases have been laid on various phenomena linked to the propagation of sound waves and their effects on the environment. The failure to respect factory-servicing norms coupled with the depreciation of parts of an industrial motor lead to additional sound production, which due to an accumulation in acoustic power and pressure levels contributes to environmental noise pollution. In this work, a study has been carried out on environmental noise pollution from a thermal power plant in Cameroon, using empirical, diagrammatic, analytical and noise map elaboration methods, with the aim of proposing an optimal protection of the surroundings of the thermal plant from the noise pollution. The results obtained show a similarity in propagation of acoustic pressure and power levels for the different types of frequencies considered. Besides these, the study has revealed that the inhabitants are exposed to sound levels higher than the upper limit of 50 dB and above the alert threshold level of 80 dB. At the geo-localized motors of the plant, the primary sources of acoustic power levels were found to fall within the range from 60 to 98 dB, which is very close to the acoustic pressure levels of between 60 and 95 dB. Due to dispersion of sound, the acoustic power levels are also felt at different points around the plant, considered here as secondary sources. From a general point of view, the observed distribution of the iso-sound contours from the collected data and their general NE-SW orientations show the development of new sources due to cumulative effects and superposition of sound waves at regular intervals. At the same time, the acoustic power and pressure levels have been found to be higher than 80 dB, which is the threshold value for human hearing. This therefore is considered detrimental to human health and wellbeing, provoking the need for a more profound investigation on the existing correlation between levels of sound due to stationary sources and frequency in a high sound medium and elaborating a strategic noise map for the town of Mbalmayo and its environs.

Proliferative effect of phospholipase A2 on rat periacinar fibroblastoid cells of the pancreas.

We have shown previously that rat pancreatic periacinar fibroblastoid cells (PFCs) can be cultured from isolated pancreatic acini. In the present study, immunocytochemical examination of the PFC extracellular matrix was performed using antibodies against prolyl hydroxylase alpha and beta subunits, types I, III, and IV collagen, fibronectin, and laminin. The PFC content of alpha-smooth muscle actin and platelet-derived growth factor (PDGF) receptor were studied by immunoblotting. We demonstrated that PFCs synthesized extracellular matrix and expressed alpha-smooth muscle actin and PDGF receptors. These results suggested that PFCs resemble myofibroblasts and may play a critical role in pancreatic fibrosis. Conversely, pancreatic-type phospholipase A2 (P-PLA2), one of the pancreatic digestive enzymes, has been shown to induce DNA synthesis of Swiss 3T3 fibroblasts. To determine whether this enzyme is involved in pancreatic fibrosis, we studied P-PLA2's proliferative and chemotactic effects on PFCs as well as its digestive activity. The proliferative and chemotactic effects were investigated using 3H-thymidine incorporation and a chemotactic assay, respectively. P-PLA2 had both proliferative and chemotactic effects. P-PLA2 is considered a growth factor for PFCs and is implicated in pancreatic fibrosis.

Macrolipasemia in Crohn's disease.

A 38-year-old male patient who had been treated for Crohn's disease was found to have serum lipase activity that was persistently increased approximately 10-fold above the normal upper limit. He was diagnosed with chronic pancreatitis based on slightly elevated elastase-1 level and retrograde pancreatography showing slight dilatation of the main pancreatic duct. Therefore, the hyperlipasemia was thought to be due to pancreatitis. However, the serum amylase and trypsin was not increased at any time, and no serious findings suggestive of pancreatitis were detected on morphologic examination. Thus, there were discrepancies between the serum lipase activity and other laboratory and clinical findings. Exclusion chromatography of the patient's serum suggested macromolecular lipase, and further immunologic testing including affinity chromatography, enzyme-linked immunosorbent assay, and immunoprecipitation assay showed that serum lipase was bound to immunoglobulin Gkappa. Therefore, the hyperlipasemia was caused by immunoglobulin-linked lipase, termed "macrolipasemia." Macrolipasemia has rarely been reported, and this is the first reported case of macrolipasemia accompanied by Crohn's disease.