Design of a scanning tunneling microscope for electrochemical applications

A design for a scanning tunneling microscope that is well suited for electrochemical investigations is presented. The construction of the microscope ensures that only the tunneling tip and the sample participate in electrochemical reactions. The design also allows rapid replacement of the tip or sample, and enables facile introduction of auxiliary electrodes for use in electrochemical experiments. The microscope utilizes stepper motor driven approach mechanics in order to achieve fully remote operation and to allow reproducible coarse control of tip/sample spacings for electrochemical experiments. Highly ordered pyrolytic graphite images at atomic resolution in air and aqueous solutions can be obtained with this microscope

Produtividade de plantações de eucalipto intercaladas com espécies nativas em áreas de pastagens degradadas no noroeste do Estado do Paraná.

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Successful combined surgical approach in a rare case of retrotracheal goitre in a patient with anatomical impediments

Diving goitres can descend the cervical region expanding directly into the thoracic cavity. In most cases, diving goitres extend into the anterosuperior compartment, but they may also extend behind the trachea. We herein present a case of a male patient with retrotracheal goitre and history of left thyroid lobectomy and median sternotomy for thoracic aortic aneurysm repair with graft placement. After detailed preoperative evaluation, the patient underwent surgical resection of the mass through a combined approach; the existing cervical incision and a right posterolateral mini-thoracotomy. The postoperative course of the patient was uncomplicated. One year after surgery, the patient is asymptomatic and disease-free. (Folia Morphol 2018; 77, 1: 166–169

Effect of density of state on isotope effect exponent of two-band superconductors

The exact formula of Tc's equation and the isotope effect exponent of two-band s-wave superconductors in weak-coupling limit are derived by considering the influence of two kinds of density of state : constant and van Hove singularity. The pairing interaction in each band consisted of 2 parts : the electron-phonon interaction and non-electron-phonon interaction are included in our model. We find that the interband interaction of electron-phonon show more effect on isotope exponent than the intraband interaction and the isotope effect exponent with constant density of state can fit to an experimental data,MgB2, and high-Tc superconductors, better than van Hove singularity density of state.Comment: 11 pages. accepted in Physica

Effects and Implications of Wearing a Face Mask on Cardiopulmonary Performance During Exercise

The coronavirus disease 2019 (COVID-19) pandemic has prompted the use of a face mask (FM) to minimize the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19. The use of an FM being an accepted precautionary measure to reduce viral transmission, there is a need for examining the physiological effects of wearing an FM, specifically during exercise. PURPOSE: To assess the impact of wearing a surgical FM on cardiopulmonary parameters and exercise performance. METHODS: Nine males and 9 females (age = 21.6 ± 2.5 yrs; BMI = 24.4 ± 3.1 kg/m2) participated in 2 laboratory visits where they completed a graded maximal exercise test using a modified Bruce Protocol. Participants were randomized to which laboratory visit they would complete first, with face mask (WFM) or without face mask (WOFM), which were performed at least 48 hours apart. Expired gases, blood pressure, heart rate, blood O2 saturation including perfusion index, and the Borg Rating of Perceived Exertion (RPE) were measured and compared between the WFM and WOFM trials at 6 different intensities (rest, 40%, 55%, 70%, 80%, and 100% VO2max), using a two-way repeated measures ANOVA. RESULTS: There was a significant difference in VO2 (p = 0.001 and n2 = 0.73) between the WFM (38.5 ± 6.8 mL/kg/min) and WOFM (44.3 ± 7.4 mL/kg/min) trials only at the 100% VO2max intensity, where significantly lower values were also found during the WFM trial for respiratory rate (40.0 ± 6.8 vs 47.8 ± 8.9 bpm, p = 0.001, n2 = 0.62), respiratory exchange ratio (1.07 ± 0.08 vs 1.14 ± 0.64, p = 0.001, n2 = 0.52), and the partial pressure of expired oxygen (125.7 ± 3.5 vs 129.4 ± 3.1 mmHg, p = 0.0001, n2 = 0.54). In contrast, the partial pressure of expired carbon dioxide (32.8 ± 3.1 vs 30.8 ± 3.3 mmHg, p = 0.01, n2 = 0.33) was significantly higher during the WFM trial only at 100% VO2max intensity. No other parameters significantly differed at any of the intensities. CONCLUSION: Oxygen consumption was lower with face masks only as participants advanced from 80% to maximal effort. Notably, participants had a slower respiratory rate and exhaled a higher concentration of carbon dioxide with face masks. This result suggests that expired carbon dioxide accumulated under the face masks and participants subsequently rebreathed this expired carbon dioxide. There is no evidence that suggests exercise below 80% of VO2max while wearing face masks will cause any concerning changes in cardiopulmonary parameters. However, it is recommended that future studies examine how different types of face masks may affect cardiopulmonary function during exercise in a variety of subject populations

Identification of Cryptic MHC I–restricted Epitopes Encoded by HIV-1 Alternative Reading Frames

Human immunodeficiency virus (HIV) 1 major histocompatibility complex (MHC) I–restricted epitopes are widely believed to be derived from viral proteins encoded by primary open reading frames. However, the HIV-1 genome contains alternative reading frames (ARFs) potentially encoding small polypeptides. We have identified a panel of epitopes encoded by ARFs within the gag, pol, and env genes. The corresponding epitopic peptides were immunogenic in mice humanized for MHC-I molecules. In addition, cytotoxic T lymphocytes recognizing these epitopes were found in HIV-infected patients. These results reveal the existence of atypical mechanisms of HIV-1 epitope generation. They indicate that the repertoire of epitopes recognized by the cellular anti–HIV-1 immune response is broader than initially thought. This should be taken into account when designing vaccine strategies aimed at activating these responses