Review of experimental research on supercritical and transcritical thermodynamic cycles designed for heat recovery application

Supercritical operation is considered a main technique to achieve higher cycle efficiency in various thermodynamic systems. The present paper is a review of experimental investigations on supercritical operation considering both heat-to-upgraded heat and heat-to-power systems. Experimental works are reported and subsequently analyzed. Main findings can be summarized as: steam Rankine cycles does not show much studies in the literature, transcritical organic Rankine cycles are intensely investigated and few plants are already online, carbon dioxide is considered as a promising fluid for closed Brayton and Rankine cycles but its unique properties call for a new thinking in designing cycle components. Transcritical heat pumps are extensively used in domestic and industrial applications, but supercritical heat pumps with a working fluid other than CO2 are scarce. To increase the adoption rate of supercritical thermodynamic systems further research is needed on the heat transfer behavior and the optimal design of compressors and expanders with special attention to the mechanical integrity

Evaluation of the economic and environmental performance of low-temperature heat to power conversion using a reverse electrodialysis - Multi-effect distillation system

In the examined heat engine, reverse electrodialysis (RED) is used to generate electricity from the salinity difference between two artificial solutions. The salinity gradient is restored through a multi-effect distillation system (MED) powered by low-temperature waste heat at 100 ◦C. The current work presents the first comprehensive economic and environmental analysis of this advanced concept, when varying the number of MED effects, the system sizing, the salt of the solutions, and other key parameters. The levelized cost of electricity (LCOE) has been calculated, showing that competitive solutions can be reached only when the system is at least medium to large scale. The lowest LCOE, at about 0.03 €/kWh, is achieved using potassium acetate salt and six MED effects while reheating the solutions. A similar analysis has been conducted when using the system in energy storage mode, where the two regenerated solutions are stored in reservoir tanks and the RED is operating for a few hours per day, supplying valuable peak power, resulting in a LCOE just below 0.10 €/kWh. A life-cycle assessment has been also carried out, showing that the case with the lowest environmental impact is the same as the one with the most attractive economic performance. Results indicate that the material manufacturing has the main impact; primarily the metallic parts of the MED. Overall, this study highlights the development efforts required in terms of both membrane performance and cost reduction, in order to make this technology cost effective in the future

COVID-19 and health passport

Η υγειονομική κρίση, όπως ξέσπασε τους τελευταίους μήνες στην Ευρώπη, έφερε μια μεγάλη σειρά αλλαγών στον καθημερινό βίο εκατομμυρίων πολιτών. Είναι μια κρίση που θα αφήσει το υλικό της αποτύπωμα στην κοινωνική και οικονομική ζωή όχι µόνο της Ευρώπης, αλλά και σε παγκόσμιο επίπεδο. Οι συνέπειες θα είναι ανυπολόγιστες εάν δε βρεθεί εγκαίρως ένα αποτελεσματικό φάρμακο ή ένα εμβόλιο. Πολλές ευρωπαϊκές οικονομίες θα καταρρεύσουν, ενώ ο τουρισμός θα υποστεί πλήγμα. Λαμβάνοντας υπόψιν τη σημασία που έχει ο τουρισμός σε πολλές χώρες της Ευρώπης, συντάξαμε το παρακάτω κείμενο που έχει ως επίκεντρο το υγειονομικό διαβατήριο ή πρωτόκολλο. Είναι μια πολιτική που πολλά ευρωπαϊκά κράτη θα ακολουθήσουν. Η προάσπιση της δημόσιας υγείας υπερβαίνει το ατομικό αγαθό, ενώ η οικονομία μπαίνει σε δεύτερη μοίρα. Μέσα από αυτήν την ανάλυση, προσπαθούμε να αποτυπώσουμε την πρόκληση που ενέχει το υγειονομικό πρωτόκολλο για την ηθική. Το υγειονομικό πρωτόκολλο διαμορφώνει μια «νέα ηθική», η οποία εγκαταλείπει το μέχρι πρότινος δεοντοκρατικό της χαρακτήρα, ενώ αποκτά ωφελιμιστικά χαρακτηριστικά. Ταυτόχρονα, γίνεται σαφής αναφορά στη δημόσια συζήτηση που λαμβάνει χώρα στην Ευρώπη, ενώ προτείνεται η θέσπιση του λεγόμενου διαβατηρίου µε παράλληλη ενδυνάμωση των ευρωπαϊκών θεσμών και διαδικασιών.The health crisis in Europe brought about a series of changes to the daily lives of millions of people in recent months. It is a crisis which will have its material mark on the social, economic life not only in Europe, but also worldwide. The consequences will be incalculable if an effective drug or vaccine will not be found in time. Many European economies will collapse, and tourism will suffer. Taking the importance of tourism in many European countries into account, we have compiled the following text focusing on the health passport or protocol. It is a policy that many European countries will follow. The defense of Public Health goes beyond the individual Good, while the economy takes second place. Through this analysis, we try to capture the challenge of health ethics. The health protocol forms a new kind of Ethics which abandons its previously ethical character, while obtains utilitarian characteristics. At the same time, the public debate as it takes place in Europe is clearly mentioned and it is also proposed the Health Passport as kind of policy. The health passport should be aligned with the strengthening of European institutions and procedures

Recurring gastrointestinal stromal tumor with splenic metastasis

Malignant gastrointestinal stromal tumors (GISTs) are rare non-epithelial, mesenchymal neoplasms of the gastrointestinal tract that metastasize or recur in 30% of patients who undergo surgical resection with curative intent. A 59-year-old man visited our hospital for an examination of a palpable mass in the left abdomen. Fourteen months prior to his visit, the patient underwent gastric wedge resection to remove a GIST of the gastric cardia. At the time of surgery, no evidence of metastatic disease was observed and the pathological interpretation was a high-risk GIST. A follow-up computed tomography scan of the abdomen revealed a partially necrotic solid mass (9.8 × 7.6 cm) and enhancing mass in the spleen (2.3 cm). On exploration, multiple masses were found in the liver, greater omentum, and mesentery. Here, we report a case of recurring GIST of the stomach that metastasized to the spleen. To the best of our knowledge, few reports of metastasis to the spleen exist

Micronutrient and amino acid losses in acute renal replacement therapy

A wide range of renal replacement therapies is now available to support patients with acute kidney injury. These treatments utilize diffusion, convection or a combination of these mechanisms to remove metabolic waste products from the bloodstream. It is inevitable that physiologically important substances including micronutrients will also be removed. Here we review current knowledge of the extent of micronutrient loss, how it varies between treatment modalities and its clinical significance. Recent findings Very few studies have specifically investigated micronutrient loss in renal replacement therapy for acute kidney injury. Recent data suggest that trace elements and amino acids are lost during intermittent dialysis, hybrid therapies such as sustained low efficiency diafiltration and continuous therapies. Extent of micronutrient loss appears to vary with treatment type, with continuous convection based treatments probably causing greatest losses. Summary Patients with acute kidney injury are at high risk of disease related malnutrition. The use of renal replacement therapy, while often essential for life support, results in loss of micronutrients into the filtrate or dialysate. Losses are probably greater with continuous convective treatments, but it is not yet known whether these losses are clinically significant or whether their replacement would improve patient outcomes

Extracorporeal photopheresis for the treatment of graft rejection in 33 adult kidney transplant recipients

Background - Extracorporeal photopheresis (ECP) has shown encouraging results in the prevention of allograft rejection in heart transplantation. However, the role of ECP in kidney transplant (KT) rejection needs to be determined. Methods - This multicentre retrospective study included 33 KT recipients who were treated with ECP for allograft rejection (23 acute antibody-mediated rejections (AMRs), 2 chronic AMRs and 8 acute cellular rejections (ACRs)). The ECP indications were KT rejection in patients who were resistant to standard therapies (n = 18) or in patients for whom standard therapies were contraindicated because of concomitant infections or cancers (n = 15). Results - At 12 months (M12) post-ECP, 11 patients (33%) had a stabilization of kidney function with a graft survival rate of 61%. The Banff AMR score (g + ptc + v) was a risk factor for graft loss at M12 (HR 1.44 [1.01-2.05], p < 0.05). The factorial mixed data analysis identified 2 clusters. Patients with a functional graft at M12 tended to have cellular and/or chronic rejections. Patients with graft loss at M12 tended to have acute rejections and/or AMR; higher serum creatinine levels; DSA levels and histologic scores of AMR; and a longer delay between the rejection and ECP start than those of patients with functional grafts. Conclusions - ECP may be helpful to control ACR or moderate AMR in KT recipients presenting concomitant opportunistic infections or malignancies when it is initiated early

Gastrointestinal stromal tumor masquerading as a lung neoplasm. A case presentation and literature review

Gastrointestinal stromal tumors (GISTs) are rare neoplasms of the gastrointestinal tract. Their incidence in the esophagus is 1%–3%. Never has a GIST been documented to directly invade the lung. We report a primary esophageal GIST with direct invasion into the lung parenchyma, presenting predominantly with respiratory symptoms. We include a retrospective literature review. Although the principle 'common things are common' usually guides our everyday clinical practice, this case emphasizes that rare entities can mimic common pathologies and underlines the importance of having a clearly defined differential diagnostic list which should be meticulously scrutinized

Fractional excretion of electrolytes in volume-responsive and intrinsic acute kidney injury in dogs: Diagnostic and prognostic implications

Background: The value of fractional excretion (FE) of electrolytes to characterize and prognosticate acute kidney injury (AKI) is poorly documented in dogs. Objectives: To evaluate the diagnostic and prognostic roles of FE of electrolytes in dogs with AKI. Animals: Dogs (n=135) with AKI treated with standard care (February 2014-December 2016). Methods: Prospective study. Clinical and laboratory variables including FE of electrolytes, were measured upon admission. Dogs were graded according to the AKI-IRIS guidelines and grouped according to AKI features (volume-responsive, VR-AKI; intrinsic, I-AKI) and outcome (survivors/non-survivors). Group comparison and regression analyses with hazard ratios (HR) evaluation for I-AKI and mortality were performed. P<.05 was considered significant. Results: Fifty-two of 135 (39%) dogs had VR-AKI, 69/135 (51%) I-AKI and 14/135 (10%) were unclassified. I-AKI dogs had significantly higher FE of electrolytes, for example, FE of sodium (FENa, %) 2.39 (range 0.04-75.81) than VR-AKI ones 0.24 (range 0.01-2.21; P<.001). Overall, case fatality was 41% (55/135). Increased FE of electrolytes were detected in nonsurvivors, for example, FENa 1.60 (range 0.03-75.81) compared with survivors 0.60 (range 0.01-50.45; P=.004). Several risk factors for death were identified, including AKI-IRIS grade (HR=1.39, P=.002), FE of electrolytes, for example, FENa (HR=1.03, P<.001), and urinary output (HR=5.06, P<.001). Conclusions and Clinical Importance: Fractional excretion of electrolytes performed well in the early differentiation between VR-AKI and I-AKI, were related to outcome, and could be useful tools to manage AKI dogs in clinical practice