Theoretical and Experimental Study of CaMgSi Thermoelectric Properties.

Pure CaMgSi was successfully synthesized by mechanical milling, followed by spark plasma sintering. Rietveld refinement was used to calculate the structural parameters, where a crystallite size (D XRD) of 79 nm was estimated. This value was confirmed by the Williamson-Hall analysis. Transmission electron microscopy was used to analyze the microstructure, revealing the presence of extensive interfaces, nanoparticles, and a high crystallinity. First-principles calculations were performed with the WIEN2k package, finding a band gap of 0.27 eV. The thermoelectric properties were determined combining experimental measurements and theoretical results from the BoltzTraP code. The highest value of the electronic figure of merit (ZT e) was 1.67 at 415 K. However, when the lattice thermal contribution (k L) is considered, the highest value of the figure of merit (ZT) was 0.144 at 644 K.

Novel Thermoelectric Character of Rhenium Carbonitride, ReCN.

Nowadays, it is very important to study and propose new mechanisms for generating electricity that are environmentally friendly, in addition to using renewable resources. Thermoelectric (TE) devices are fabricated with materials that can convert a temperature difference into electricity, without the need for rotating parts. In this work, we report the TE properties of rhenium carbonitride (ReCN) as an important feature of a hard and thermodynamically stable material of band gap Δg = 0.626 eV. We use the electronic band structure behavior near the Fermi energy with the Seebeck coefficient to estimate the figure of merit ZT based on Boltzmann transport theory to characterize this property. Our results show that this compound has interesting TE properties among 300 and 1200 K for p- and n-type doping.

Impact of Model for End-Stage Liver Disease in the occurrence of infectious events and survival in a cohort of liver transplant recipients.

The Model for End-Stage Liver Disease (MELD), which predicts mortality on the waiting list before liver transplantation, has changed organ allocation criteria to prioritize severely ill patients. The aim of this study was to investigate the impact of the new criteria on the incidence of Healthcare Associated Infections (HAI) and patient survival after liver transplantation. This retrospective cohort included liver transplant recipients from 2005 to 2007. Infection notification followed the recommended criteria of the National Healthcare Safety Network (NHSN). Statistical analysis was performed using the Statistical Package for the Social Sciences. Of 142 patients, 67 (47.2%) underwent transplantation before June 2006. There were no differences between the 2 periods considering patient gender, diagnosis, age, length of hospitalization, and mean time to first infection occurrence. However, the length of intensive care unit (ICU) hospitalization (P = .006) and central venous catheter (CVC) use (P = .025) were higher in the first period of the study. Comparison of time until first systemic infection before and after changes in allocation criteria showed no significant difference (log-rank = 0.06; P = .81). There was a trend toward greater lethality during the second period of the study (P = .09). There was no difference in time to death between the 2 periods (log-rank = 0.9; P = .76). However, when comparing time to death of all patients with systemic infection versus those without this event, patients without infection showed a higher mortality rate (log-rank = 15.7; P < .001).

The type 2 iodothyronine deiodinase is essential for adaptive thermogenesis in brown adipose tissue.

Type 2 iodothyronine deiodinase (D2) is a selenoenzyme, the product of the recently cloned cAMP-dependent Dio2 gene, which increases 10- to 50-fold during cold stress only in brown adipose tissue (BAT). Here we report that despite a normal plasma 3,5,3'-triiodothyronine (T3) concentration, cold-exposed mice with targeted disruption of the Dio2 gene (Dio2(-/-)) become hypothermic due to impaired BAT thermogenesis and survive by compensatory shivering with consequent acute weight loss. This occurs despite normal basal mitochondrial uncoupling protein 1 (UCP1) concentration. In Dio2(-/-) brown adipocytes, the acute norepinephrine-, CL316,243-, or forskolin-induced increases in lipolysis, UCP1 mRNA, and O(2) consumption are all reduced due to impaired cAMP generation. These hypothyroid-like abnormalities are completely reversed by a single injection of T3 14 hours earlier. Recent studies suggest that UCP1 is primarily dependent on thyroid hormone receptor beta (TR beta) while the normal sympathetic response of brown adipocytes requires TR alpha. Intracellularly generated T3 may be required to saturate the TR alpha, which has an approximately fourfold lower T3-binding affinity than does TR beta. Thus, D2 is an essential component in the thyroid-sympathetic synergism required for thermal homeostasis in small mammals.

[Rheumatic diseases. A three-year retrospective study at an internal medicine service]. / Doenças reumáticas. Estudo retrospectivo de três anos num serviço de medicina interna.

In order to assess the weight of Rheumatic Diseases, the Authors retrospectively studied 117 patients admitted to the Internal Medicine Service of the Faro District Hospital over a 3 year period (1989-1991). The selection criterion comprised the final rheumatological diagnosis. The diseases were arranged in nosological groups according to the Classification of Rheumatic Diseases of the American Rheumatism Association. The relative frequency, in totality and by nosological groups, and other variables, were determined. The relative frequency was of 4.2%. The mean age was 52.9 years. The distribution in age groups showed 2 peaks in the sixth and seventh decades. Females were more often affected (61%). The mean time of internment was 22.3 days. The proportional mortality reached 6.8%. Diffuse Connective Tissue Diseases were the most frequently found (42.7%) and among these Rheumatoid Arthritis and Systemic Lupus Erythematous were the most prevailing.