Permeability correction factor for fractures with permeable walls

Enhanced Geothermal Systems (EGS) are based on the premise that heat can be extracted from hot dry rocks located at significant depths by circulating fluid through fracture networks in the system. Heated fluid is recovered through production wells and the energy is extracted in a heat exchange chamber. There is much published research on flow through fractures, and many models have been developed to describe an effective permeability of a fracture or a fracture network. In these cases however, the walls of the fracture were modelled as being impermeable. In this paper, we have extended our previous work on fractures with permeable walls, and we introduce a correction factor to the equation that governs fracture permeability. The solution shows that the effective fracture permeability for fractures with permeable walls depends not only on the height of the channel, but also on the wall permeability and the wall Reynolds number of the fluid. We show that our solution reduces to the established solution when the fracture walls become impermeable. We also extend the discussion to cover the effective permeability of a system of fractures with permeable walls.R. Mohais, C. Xu, P. A. Dowd, and M. Han

Influence of stress-induced and thermal cracking on physical properties and microstructure of La Peyratte granite

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Autophagy mediates the mitotic senescence transition

As a stress response, senescence is a dynamic process involving multiple effector mechanisms whose combination determines the phenotypic quality. Here we identify autophagy as a new effector mechanism of senescence. Autophagy is activated during senescence and its activation is correlated with negative feedback in the PI3K–mammalian target of rapamycin (mTOR) pathway. A subset of autophagy-related genes are up-regulated during senescence: Overexpression of one of those genes, ULK3, induces autophagy and senescence. Furthermore, inhibition of autophagy delays the senescence phenotype, including senescence-associated secretion. Our data suggest that autophagy, and its consequent protein turnover, mediate the acquisition of the senescence phenotype

Comparison of gaseous cryotherapy with more traditional forms of cryotherapy following total knee arthroplasty

AbstractObjectiveThe aim of this study was to assess the efficacy of gaseous cryotherapy following total knee arthroplasty (TKA) and to compare it to routinely used strategies for applying cold therapy.Patients and methodsSixty-six patients undergoing primary unilateral TKA were randomized into three groups and received “gaseous cryotherapy (GC)”, “cold pack” and “cryocuff” applications, respectively throughout the hospital stay. Primary outcomes (knee pain intensity, mobility and girth measurements) were recorded on preoperative day 1 as well as on postoperative day (POD) 7. Cutaneous temperature of the knee sides were also measured on POD7 just before and immediately after cold application.ResultsAlthough skin temperature dropped to 14°C following GC versus 22 to 24°C for the other two applications (P<0,05), the three groups did not differ at POD7 regarding the three primary outcomes. No adverse effects were observed with any of the ways of application.ConclusionsGaseous cryotherapy was not more beneficial than routinely used strategies for applying cold therapy. Further studies with larger sample size and with a more frequent and closer gaseous cryotherapy applications are needed to confirm our results