Tribological properties of PVD coatings with lubricating films

Abstract. This work reports on the tribological performance of three different commercial hard PVD coatings (TiN, TiCN and nACo) with lubricating extra films of Al 2 O 3 , Ni-WS 2 and diamondlike carbon (DLC). WC-Co hardmetal has been used as substrate material. Wear tests, employing two counter bodies of Al 2 O 3 and hardmetal WC-Co, were performed for the PVD coatings with and without the extra films. The results showed that the presence of DLC extra film reduces the coefficient of friction of the PVD hard coatings TiN and nACo. Furthermore, the wear of TiN coatings was reduced in the presence of an extra Ni-WS 2 lubricant film

Direct liquid injection chemical vapor deposition of ZrO2 films from a heteroleptic Zr precursor: Interplay between film characteristics and corrosion protection of stainless steel

The direct liquid injection chemical vapor deposition (DLI-CVD) of uniform and dense zirconium oxide (ZrO2) thin films applicable as corrosion protection coatings (CPCs) is reported. We present the entire development chain from the rational choice and thermal evaluation of the suitable heteroleptic precursor [Zr(OiPr)2(tbaoac)2] over the detailed DLI-CVD process design and finally benchmarking the CPC behavior using electrochemical impedance spectroscopy (EIS). For a thorough development of the growth process, the deposition temperature (Tdep) is varied in the range of 400 – 700 °C on Si(100) and stainless steel (AISI 304) substrates. Resulting thin films are thoroughly analyzed in terms of structure, composition, and morphology. Grazing incidence X-ray diffractometry (GIXRD) reveals an onset of crystallization at Tdep ≥ 500 °C yielding monoclinic and even cubic phase at low temperatures. At Tdep = 400 °C, isotropic growth of XRD amorphous material is shown to feature cubic crystalline domains at the interfacial region as revealed by electron diffraction. Corrosion results obtained through EIS measurements and further immersion tests revealed improved CPC characteristic for the 400 °C processed ZrO2 coatings compared to the ones deposited at Tdep ≥ 500 °C, yielding valuable insights into the correlation between growth parameter and CPC performance which are of high relevance for future exploration of CPCs

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Metabolic inflexibility and insulin resistance in obese adolescents with non-alcoholic fatty liver disease.

BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a comorbidity of childhood obesity. OBJECTIVE We examined whole-body substrate metabolism and metabolic characteristics in obese adolescents with vs. without NAFLD. SUBJECTS Twelve obese (BMI ≥ 95th percentile) adolescents with and without NAFLD [intrahepatic triglyceride (IHTG) ≥5.0% vs. <5.0%] were pair-matched for race, gender, age and % body fat. METHODS Insulin sensitivity (IS) was assessed by a 3-h hyperinsulinemic-euglycemic clamp and whole-body substrate oxidation by indirect calorimetry during fasting and insulin-stimulated conditions. RESULTS Adolescents with NAFLD had increased (p  0.1) between groups. Adolescents with NAFLD had higher (p < 0.05) fasting glucose oxidation and a tendency for lower fat oxidation. Adolescents with NAFLD had lower (p < 0.05) insulin-stimulated glucose disposal and lower peripheral IS compared with those without NAFLD. Although respiratory quotient (RQ) increased significantly from fasting to insulin-stimulated conditions in both groups (main effect, p < 0.001), the increase in RQ was lower in adolescents with NAFLD vs. those without (interaction, p = 0.037). CONCLUSION NAFLD in obese adolescents is associated with adverse cardiometabolic profile, peripheral insulin resistance and metabolic inflexibility

Latent tuberculosis infection among patients with coronary artery stenosis: A case–Control study

Background: The activation of the cell-mediated immune responses by Mycobacterium tuberculosis can promote atherogenesis. Aims: The aim of this study is to determine the frequency of latent tuberculosis infection (LTBI) among patients with coronary artery stenosis (CAS) and to explore the association between LTBI and development of CAS. We conducted a case–control study which included 183 patients′ who underwent percutaneous coronary angiography (121 patients with CAS and 62 patients without as a control group). Methods: For all the study population, clinical evaluation, tuberculin skin test (TST), imaging studies (including chest radiography and echocardiography), laboratory investigations, and electrocardiography were carried out. Only for the patients with positive TST, QuantiFERON-TB Gold test was performed. Predictors of CAS were identified using univariate analyses (Yates' corrected Chi-square test or Fischer's exact test) followed by multivariate analysis (binary logistic regression). Results: Among 29.5% of the study population, LTBI was detected, and among patients with CAS, 56.2% of patients had advanced CAS. After multivariate analysis, it was found that metabolic syndrome (MS) (odds ratio [OR] 3.6, 95% confidence interval [CI] 1.5–22.6, P = 0.022) and LTBI (OR 2.5, 95% CI 1.2–17.3, P = 0.018) were the predictors of CAS among the study population, while only diabetes mellitus (DM) (OR 1.9, 95% CI 1.1–11.7, P = 0.031) was the predictor of advanced CAS. Conclusion: LTBI is associated with the development of CAS. In addition, MS is associated with CAS, while its related disorder, DM, is associated with advanced CAS