Bench investigation of the accuracy of the dynamic approach in respiratory mechanics during noninvasive ventilation with different pressure support levels

Background: Under the dynamic conditions of non-invasive mechanical ventilation, respiratory system mechanics parameters, including compliance (Crs) and airway resistance (Rrs), are affected by systemic and ventilator parameters. We evaluated the accuracy of respiratory mechanics in the dynamic approach in different lung disease models during pressure support ventilation (PSV).Methods: A Respironics V60 ventilator was connected to an active lung simulator for modeling four profiles of respiratory mechanics: normal, restrictive, obstructive and mixed obstructive/restrictive. PSV and positive end-expiration pressure (PEEP) were 2-25 cmH2O and 5 cmH2O, respectively. Measurements were performed with an air leak of 25-28 L/min. Ventilator performance and patient-ventilator asynchrony were evaluated by measuring flow, airway pressure, and volume. Crs and inspiratory/expiratory resistance (Rinsp/Rexp) were calculated by dynamic approach. Results: Crs was overestimated with pressure support (PS) at 5 cmH2O. Peak inspiratory/expiratory flow (PIF/PEF) and tidal volume (VT) was increased with PS level, while calculated Crs was decreased. At PS 10-15 cmH2O, the difference between calculated and preset Crs was ≤20% in higher resistance models (obstructive and mixed). In normal resistance conditions (restrictive and normal), the calculated Crs was always larger than the preset value significantly regardless of PS. Underestimations of Rinsp and Rexp were observed at PS 5-10 cmH2O. The calculation error might be controlled within 10% when PS above 15 cmH2O in higher resistance models. Conclusion: Higher gas flow is beneficial for Rrs estimation by using dynamic approach, whereas the calculation of Crs is always overestimated in normal resistance conditions.

Functional comparison of the group III hybrid histidine kinases TcsC of Aspergillus fumigatus and NikA of Aspergillus nidulans

In filamentous fungi, group III hybrid histidine kinases (HHKs) are major and nonredundant sensing proteins of the high osmolarity glycerol pathway. In this study, we have compared the biological functions of the two homologous group III HHKs TcsC of Aspergillus fumigatus and NikA of A. nidulans. As expected from previous studies, the corresponding mutants are severely impaired in their ability to adapt to hyperosmotic stress and are both resistant to the antifungal agent fludioxonil. However, our data also reveal novel phenotypes and differences between these mutants. Both TcsC and NikA are required for wild-type-like growth on Czapek-Dox medium and a normal resistance to certain oxidative stressors, whereas an increased resistance to the cell wall disturbing agents Congo red and Calcofluor white was found for the ΔtcsC but not for the ΔnikA mutant. With respect to the cell wall reorganizations that are triggered by fludioxonil in a TcsC/NikA-dependent manner, we observed similarities but also striking differences. Strains from seven Aspergillus species, including A. fumigatus and A. nidulans incorporated more chitin into their cell walls in response to fludioxonil. In contrast, fludioxonil treatment resulted in a shedding of surface accessible galactomannan and β-1,3-glucan in all Aspergillus strains tested except A. nidulans. Hence, the fludioxonil-induced activation of NikA results in a distinct and apparently A. nidulans-specific pattern of cell wall reorganizations that is not due to NikA itself, but its integration into the A. nidulans signaling network.

VALIDAÇÃO DA EXPRESSÃO APROXIMADA DA RIGIDEZ SECANTE ADIMENSIONAL (KAPPA) PARA CONCRETO DE ALTA RESISTÊNCIA [ Validation of non-dimensional secant stiffness (kappa) approximated expression for high strength concrete ]

RESUMO: Concretos de alta resistência (CAR) estão inseridos no grupo II de resistência e possuem fck superior a 50 MPa. Eles possuem curvas tensão-deformação com limites distintos daqueles convencionados como concretos de resistência normal. Por isso, o uso da rigidez secante adimensional apresentada pela norma brasileira de concreto armado – NBR6118 (ABNT, 2014) – necessita de validação para CAR. Para essa validação da expressão que consta na norma brasileira para CAR, foram analisadas disposições de armadura consideradas mais desfavoráveis para a resistência (altos valores de d’/h), com várias taxas mecânicas de armadura. Foram comparados os momentos máximos de 1ª ordem que poderiam ser aplicados na seção caso se considerasse a rigidez kappa a partir do diagrama momento-curvatura, com aqueles momentos obtidos considerando a rigidez kappa aproximada por expressão normativa. Em apenas 4,26% dos 5.840 casos analisados, o valor aproximado resultou maior que o valor real. A maior diferença entre os valores de máximos momentos de primeira ordem obtidos por meio da rigidez adimensional real e aproximada foi de 7,27%, o que pode ser considerado aceitável. Dessa forma a expressão aproximada da rigidez kappa prescrita pela NBR6118 (ABNT, 2014) também é válida para CAR.ABSTRACT: High strength concretes (HSC) are presented in group II of resistance and have compression strength greater than 50 MPa at 28 days. They have stress-strain curves with different limits from those referred as normal resistance concretes. Therefore, the use of the non-dimensional secant stiffness presented by the Brazilian Code of Reinforced Concrete - NBR6118 (ABNT, 2014) - needs validation for HSC. Unfavorable dispositions of steel bar reinforcement (high values of d '/ h), with a several mechanical rates of reinforcement, were analyzed for validation of the expression that appears in the Brazilian Code for HSC. It was compared the maximum moment of 1st order that could be applied in the section if the kappa stiffness was considered from the moment-curvature diagram, with those moments obtained with the normative expression for kappa stiffness. The approximate value was greater than the real value in only 4.26% of the 5840 cases analyzed. The greatest difference between the values of maximum first-order moments obtained by the real and the approximate non-dimensional stiffness was 7.27%, which can be considered acceptable. Thus the approximate expression of the kappa stiffness prescribed by NBR6118 (ABNT, 2014) is also valid for HSC.

Technology for NbN HEB based multipixel matrix of THz range

—The influence of homogeneity disorder degree of the thin superconducting NbN film across of Si wafer on characteristics of the Hot Electron Bolometers (HEB) has been investigated. Our experiments have been carried out near the superconducting transition and far below it. The high homogeneity disorder degree of the NbN film has been achieved by preparing the Si substrate surface. The fabricated HEBs all have almost identical R (T) characteristics with a dispersion of Tc and the normal resistance R300 of not more than 0.15K and 2 Ω, respectively. The quality of the devises allows us to demonstrate clearly the influence of non-equilibrium processes in the S’SS’ system on the device performance. Our fabrication technology also allows creating multiplex heterodyne and direct detector matrices based the HEB devices.

A Multi-Functional Resistance Furnace for Industrial Thermogravimetric Analysis

A multi-functional resistance furnace has been invented. Its main components include a normal resistance furnace and an electronic balance outside the furnace. The weight of the sample being heated inside the furnace was transmitted through a set of attachments and measured by the balance. Both the real-time furnace temperatures and the sample weights were recorded by a computer. Thermogravimetric curves then can be obtained. The present setup is advantageous over the traditional commercial thermogravimetric analyzers in analyzing samples with a large mass. The multi-functional furnace is cheap and may find important industrial applications such as raw materials thermal analysis or products oxidation or anti-oxidation tests.