Dartmouth Medical School bicentennial

To investigate the regulation of cell-to-cell coupling in myocardial ischaemia, the three-dimensional expression of connexin43 (Cx43) during experimental ischaemia was examined using a confocal laser scanning microscope. After induction of myocardial infarction in rats, serial optical sections were obtained from the left ventricular myocardium at various times (3 h to 60 days after ligation). The expression of Cx43 was detected immunohistochemically with FITC-labelled anti-rat Cx43 antibody. Fluorescent dots of Cx43 remained along the intercalated disc and decreased in number around the infarct up to 12 h after ligation. Cx43-expression disappeared completely within 48 h after ligation. After day 4, and especially on days 8 and 15 after ligation, the edges of the cardiomyocytes bordering the infarcted area manifested numerous sarcoplasmic tentacles that reacted positively to anti-desmin antibody. Distinct expression of Cx43 was observed extensively on the tentacles, although no cardiomyocytes remained viable around them. By day 60 after ligation, atypical expression of Cx43 had disappeared. These findings suggest that ischaemia induces temporally abnormal expression of Cx43, which might be responsible for abnormal conduction around the infarct.     

Influence of the size of membrane foulants on the filterability of WWTP-effluent.

The application of membrane filtration for the polishing of wastewater treatment plant (wwtp) effluent is more and more widely used. However, fouling problems are still not well understood. In order to investigate the role of particles in dead-end ultrafiltration of wwtp-effluent, Roorda studied the influence of pre-filtrated wwtp-effluent on the filterability. In addition this research investigates the relation between the filterability of the different fractions in the wwtp-effluent and the amount of organic foulants in these fractions. The results show a relation between the filterability and supra-dissolved particles in the fractions < 0.45 and < 0.2 microm. The amount of COD, colour, proteins and polysaccharides in these fractions are found of minor importance. A significant increase in filterability is found between the fractions < 0.2 and < 0.1 microm as well as a significant decrease in amount of polysaccharides. It is suggested that an essential feature in understanding membrane fouling during ultrafiltration of wwtp-effluent is to investigate the influence of supra-dissolved particles on the filterability as well as the influence of the amount of organic foulants (total organic carbon, proteins, polysaccharides, colour and humic substances) on the reversibility.     

Evaluating the Costs and Benefits of Salt Management Strategies at Mine Sites Using a Systems Model

Unprecedented expansion of coal mining in Australia is occurring within the context of a severe ongoing drought. This has induced more companies to adopt improved water management strategies, such as water reuse. A direct consequence of this is an increase in the salt concentration of the water, which affects in turn the efficiency of the coal preparation processes, the quality of the coal product, and the level of required equipment maintenance. There are three strategies that can be adopted with respect to salt management: accept the elevated salt concentrations and increase spending on equipment maintenance; remove the salt by desalination; and dilute the salt by importing more water. A tool is required to predict the salt concentrations arising from water reuse and to simulate the impact of potential management strategies. This paper presents a systems approach to the modelling of coupled mine site water and salt balances to assist with understanding the implications of implementing desalination or dilution and with assessing the costs and benefits of each option.