Experimental and Theoretical Studies on Possibility of Void Filling by Magnesium in Mg-Doped Tetrahedrites

Tetrahedrites, due to their promising thermoelectric properties, are one of the materials being investigated for use in thermoelectric generators. One problem is the lack of n-type tetrahedrites, which would be beneficial for the design of tetrahedrite thermoelectric modules. Preliminary theoretical studies have shown that elements from groups I and II can be introduced into the structural voids of tetrahedrite, acting as donor dopants, and should enable n-type conductivity. Therefore, in this work, an attempt was made to obtain and study magnesium-doped tetrahedrites. A series of samples, Mg_xCu₁₂Sb₄S₁₃, with different magnesium contents were obtained and their phase and chemical compositions were characterized. It was observed that the structural changes occurring upon doping indicate that Mg atoms are likely to be embedded in the structural voids. The experimental studies have been supported by electronic structure calculations indicating that the most likely location of Mg is in the structural voids at the 6b Wyckoff position. Seebeck coefficient and resistivity measurements showed that doping with Mg reduces the concentration of holes, which is consistent with the predicted donor character of the dopant. However, the introduction of magnesium in sufficient amounts to achieve n-type conductivity was not successful.     

The hydrochemistry of peatland lakes as a result of the morphological characteristics of their basins

The physico-chemical water characteristics and basin morphology of 10 well-preserved Pomeranian peatland lakes were examined. These are acidic (pH 3.95–5.99), softwater (1.5 ±0.9 mg Ca dm^?3), and oligotrophic water bodies. Their hydrochemical conditions differentiate them into two groups: poor (3.04 ±2.77 mg C dm^?3) and rich (10.36 ±7.27 mg C dm^?3) in organic carbon compounds. They differ in water colour (p = 0.02), humic acid concentration (p<0.001), redox potential (p = 0.007), and irradiance (PAR; p = 0.03). The hydrochemistry of the lakes is determined by their basin morphology, which affects the water colour and the concentrations of humic acids and organic carbon compounds.     

Effect of Transmural Extent of the Simulated Infarction in a Left Ventricular Model on Displacement and Strain Distribution Estimated from Synthetic Ultrasonic Data

The identification of a sub-endocardial infarction is of major interest in cardiology. This study evaluates the sensitivity of selected measures to the thickness of such an infarction. Synthetic ultrasonic data (long-axis view) of left ventricular models with inclusions were generated using Field II and meshes obtained from finite-element simulations, which also provided the reference for the estimates obtained from ultrasonic data. The displacements, the first and second component of the principal strain (ε₁ and ε₂), and several measures derived from these quantities were estimated. All estimates, except for the poorly estimated ε₂, exhibited sensitivity to the presence and transmurality of the inclusion. The most sensitive was the gradient of the averaged transmural profiles of ε₁, and ε₁ averaged over the area corresponding to the transmural inclusion. The inflection point of the ε₁ profile shifted toward the outer wall with increasing thickness of the non-transmural inclusion.     

Reducing delirium and cognitive dysfunction after off-pump coronary bypass: A randomized trial

BackgroundNeuropsychiatric complications of surgical coronary revascularization are inconspicuous but frequent and clinically relevant. So far, attempts to reduce their occurrence, such as the introduction of off-pump coronary artery bypass (OPCAB) grafting method, have not brought the desired results. The aim of this trial was to determine whether using any of the 2 selected modifications of OPCAB could decrease the incidence of these undesired sequelae.MethodsIn this single-center, assessor- and patient-blinded, superiority, randomized controlled trial, 192 patients scheduled for elective isolated OPCAB were randomized to 3 parallel arms. The control arm underwent “conventional” OPCAB with vein grafts. The first study arm underwent anaortic OPCAB (ANA) with total arterial revascularization. The second study arm underwent OPCAB with vein grafts using carbon dioxide surgical field flooding (CO₂FF). Outcomes included the incidence of postoperative delirium (PD) and early postoperative cognitive dysfunction (ePOCD).ResultsThe incidence of PD was 35.9% in the control (OPCAB) arm, 32.8% in the CO₂FF arm, and 12.5% in the ANA arm (χ² [2, N = 191] = 10.17; P = .006). Post hoc tests revealed that the incidence of PD in the ANA arm differed from that in the OPCAB arm (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.09-0.68; P = .002). The incidence of ePOCD was 34.4% in the OPCAB arm, 28.1% in the CO₂FF arm, and 9.5% in the ANA arm (χ² [2, N = 191] = 11.58; P = .003). Post hoc tests revealed that the incidence of ePOCD differed between the ANA and OPCAB arms (OR, 0.20; 95% CI, 0.06-0.58; P < .001).ConclusionsPerforming ANA significantly decreases the incidence of PD and ePOCD compared with “conventional” OPCAB with vein grafts, whereas CO₂FF is inconsequential in this regard. These results, which probably reflect decreased delivery of embolic load to the brain in ANA, may have practical applicability in daily practice to improve clinical outcomes.     

Contemporary use of P2Y12 inhibitors in patients with ST-segment elevation myocardial infarction referred to primary percutaneous coronary interventions in Poland: Data from ORPKI national registry

Journal of Thrombosis and Thrombolysis - According to guidelines, it is recommended to give P2Y12 inhibitors (preferably ticagrelor or prasugrel) at the time of first medical contact in patients...     

Epithelioid hemangioendothelioma of the liver as a rare indication for liver transplantation

AIM: To investigate the indications and outcomes of liver transplantation for hepatic epithelioid hemangioendothelioma (HEHE).METHODS: Between 1989 and August 2013, in the Department of General, Transplant, and Liver Surgery, Medical University of Warsaw, 1306 orthotopic liver transplantations (OLTx) were performed, including 72 retransplantations. Unresectable HEHE was an indication for OLTx in 10 patients (0.8% of primary OLTx), the mean age of the patients was 40.5 ± 13.3 years (range 23-65 years), and the male-to-female ratio was 2:8. Kaplan-Meier survival analysis in HEHE, hepatocellular carcinoma (HCC), and other OLTx recipients groups was performed. The differences in mortality were compared using the χ² test. A P-value < 0.05 indicated statistical significance.RESULTS: No concomitant liver disease was found in any patient. There was no neoadjuvant chemotherapy or radiotherapy. Liver function test results were normal in most of the patients. The levels of alpha-fetoprotein, carcinoembryonic antigen, and carbohydrate antigen 19-9 were normal. In immunohistochemical staining, the neoplastic cells were positive for factor VIII-related antigen, CD31, and CD34, which are endothelial cell markers, and negative for cytokeratin 19, cytokeratin 7, and HepPar-1. Nine patients were alive without tumor recurrence. One patient died 2 mo after OLTx due to septic complications. No morbidity was observed. Maximum follow-up was 11.4 years, with a minimum of 1 mo. The cumulative survival rate at the end of follow-up in HEHE patients was 87.5% compared with 54.3% in the HCC group and 76.3% in the other OLTx recipients group (χ² test = 1.784, df = 2, P = 0.409).CONCLUSION: Unresectable HEHE, without extrahepatic metastases is an excellent indication for liver transplantation. Long-term survival is very good and much better than in HCC patients and the entire group of OLTx patients.