53 resultados para DIFFERENT ADHESIVE SYSTEMS
Resumo:
Context. Solar and extrasolar planets are the subject of numerous studies aiming to determine their chemical composition and internal structure. In the case of extrasolar planets, the composition is important as it partly governs their potential habitability. Moreover, observational determination of chemical composition of planetary atmospheres are becoming available, especially for transiting planets. Aims. The present works aims at determining the chemical composition of planets formed in stellar systems of solar chemical composition. The main objective of this work is to provide valuable theoretical data for models of planet formation and evolution, and future interpretation of chemical composition of solar and extrasolar planets. Methods. We have developed a model that computes the composition of ices in planets in different stellar systems with the use of models of ice and planetary formation. Results. We provide the chemical composition, ice/rock mass ratio and C:O molar ratio for planets in stellar systems of solar chemical composition. From an initial homogeneous composition of the nebula, we produce a wide variety of planetary chemical compositions as a function of the mass of the disk and distance to the star. The volatile species incorporated in planets are mainly composed of H2O, CO, CO2, CH3OH, and NH3. Icy or ocean planets have systematically higher values of molecular abundances compared to giant and rocky planets. Gas giant planets are depleted in highly volatile molecules such as CH4, CO, and N2 compared to icy or ocean planets. The ice/rock mass ratio in icy or ocean and gas giant planets is, respectively, equal at maximum to 1.01 ± 0.33 and 0.8 ± 0.5, and is different from the usual assumptions made in planet formation models, which suggested this ratio to be 2–3. The C:O molar ratio in the atmosphere of gas giant planets is depleted by at least 30% compared to solar value.
Resumo:
In aerobic eukaryotic cells, the high energy metabolite ATP is generated mainly within the mitochondria following the process of oxidative phosphorylation. The mitochondrial ATP is exported to the cytoplasm using a specialized transport protein, the ADP/ATP carrier, to provide energy to the cell. Any deficiency or dysfunction of this membrane protein leads to serious consequences on cell metabolism and can cause various diseases such as muscular dystrophy. Described as a decisive player in the programmed cell death, it was recently shown to play a role in cancer. The objective of this review is to summarize the current knowledge of the involvement of the ADP/ATP carrier, encoded by the SLC25A4, SLC25A5, SLC25A6 and SLC25A31 genes, in human diseases and of the efforts made at designing different model systems to study this carrier and the associated pathologies through biochemical, genetic, and structural approaches.
Resumo:
Ethnobiology research contributes significantly to initiatives that aim to enhance food sovereignty among indigenous and/or traditional people. In Bolivia, one of the Latin-American countries that shows the highest poverty and undernourishment levels, the purpose of this research-action project was to enhance food sovereignty through the revitalization of the local ecological knowledge and to promote local technological innovation processes in the Andean community of Tallija-Confital. During a first step the endogenous knowledge and strategies related to food security and sovereignty were investigated, based on the principles and tools of the Revitalizing Participatory Research (RPR). In a second step local technical innovation processes were supported through a “knowledge dialogue” between exogenous and endogenous knowledge systems, focusing on the processing of the cañahua (Chenopodium pallidicaule Aellen) gluten. The research results demonstrate that Andean people have developed complex endogenous knowledge and strategies to adapt to socio-environmental changes that show a great potential to contribute to the enhancement of food sovereignty. Nevertheless, in the current globalized context that translates into new challenges for local communities, beyond the revitalization of local ecological knowledge, a dialogue between different knowledge systems can lead to important local technological innovation for the improvement of their well-being. Key words: food sovereignty, knowledge dialogue, endogenous development, technological innovation
Resumo:
Blame avoidance behaviour (BAB) has become an increasingly popular topic in political science. However, the preconditions of BAB, its presence and consequences in various areas and in different political systems largely remain a black box. In order to generate a better understanding of BAB and its importance for the workings of democratic political systems, the scattered literature on BAB needs to be assessed and structured. This article offers a comprehensive review of the literature on blame avoidance. It departs from Weaver’s concept of blame avoidance and subsequently differentiates between work on BAB in comparative welfare state research and work on BAB in public policy and administration. It is argued that between these two strands of literature a bifurcation exists since both perspectives rarely draw on each other to create a more general understanding of BAB. Advantages from existing approaches must be combined to assess the phenomenon of blame avoidance in a more comprehensive way.
Resumo:
Land systems are the result of human interactions with the natural environment. Understanding the drivers, state, trends and impacts of different land systems on social and natural processes helps to reveal how changes in the land system affect the functioning of the socio-ecological system as a whole and the tradeoff these changes may represent. The Global Land Project has led advances by synthesizing land systems research across different scales and providing concepts to further understand the feedbacks between social-and environmental systems, between urban and rural environments and between distant world regions. Land system science has moved from a focus on observation of change and understanding the drivers of these changes to a focus on using this understanding to design sustainable transformations through stakeholder engagement and through the concept of land governance. As land use can be seen as the largest geo-engineering project in which mankind has engaged, land system science can act as a platform for integration of insights from different disciplines and for translation of knowledge into action.
Resumo:
Purpose: To investigate the effect of airborne-particle abrasion or diamond bur preparation as pretreatment steps of non-carious cervical root dentin regarding substance loss and bond strength. Methods: 45 dentin specimens produced from crowns of extracted human incisors by grinding the labial surfaces with silicon carbide papers (control) were treated with one of three adhesive systems (Group 1A-C; A: OptiBond FL, B: Clearfil SE Bond, or C: Scotchbond Universal; n=15/adhesive system). Another 135 dentin specimens (n=15/group) produced from the labial, non-carious cervical root part of extracted human incisors were treated with one of the adhesive systems after either no pre-treatment (Group 2A-C), pre-treatment with airborne-particle abrasion (CoJet Prep and 50 µm aluminum oxide powder; Group 3A-C), or pre-treatment with diamond bur preparation (40 µm grit size; Group 4A-C). Substance loss caused by the pre-treatment was measured in Groups 3 and 4. After treatment with the adhesive systems, resin composite was applied and all specimens were stored (37°C, 100% humidity, 24 hours) until measurement of microshear bond strength (µSBS). Data were analyzed with a nonparametric ANOVA followed by Kruskal-Wallis and Wilcoxon rank sum tests (level of significance: alpha=0.05). Results: Overall substance loss was significantly lower in Group 3 (median: 19 µm) than in Group 4 (median: 113 µm; p<0.0001). There were no significant differences in µSBS between the adhesive systems (A-C) in Group 1, Group 3, and Group 4 (p>=0.133). In Group 2, OptiBond FL (Group 2A) and Clearfil SE Bond (Group 2B) yielded significantly higher µSBS than Scotchbond Universal (Group 2C; p<=0.032). For OptiBond FL and Clearfil SE Bond, there were no significant differences in µSBS between the ground crown dentin and the non-carious cervical root dentin regardless of any pre-treatment of the latter (both p=0.661). For Scotchbond Universal, the µSBS to non-carious cervical root dentin without pre-treatment was significantly lower than to ground crown dentin and to non-carious cervical root dentin pre-treated with airborne-particle abrasion or diamond bur preparation p<=0.014).
Resumo:
OBJECTIVE To evaluate whether magnetic resonance imaging (MRI) is effective as computed tomography (CT) in determining morphologic and functional pulmonary changes in patients with cystic fibrosis (CF) in association with multiple clinical parameters. MATERIALS AND METHODS Institutional review board approval and patient written informed consent were obtained. In this prospective study, 30 patients with CF (17 men and 13 women; mean (SD) age, 30.2 (9.2) years; range, 19-52 years) were included. Chest CT was acquired by unenhanced low-dose technique for clinical purposes. Lung MRI (1.5 T) comprised T2- and T1-weighted sequences before and after the application of 0.1-mmol·kg gadobutrol, also considering lung perfusion imaging. All CT and MR images were visually evaluated by using 2 different scoring systems: the modified Helbich and the Eichinger scores. Signal intensity of the peribronchial walls and detected mucus on T2-weighted images as well as signal enhancement of the peribronchial walls on contrast-enhanced T1-weighted sequences were additionally assessed on MRI. For the clinical evaluation, the pulmonary exacerbation rate, laboratory, and pulmonary functional parameters were determined. RESULTS The overall modified Helbich CT score had a mean (SD) of 15.3 (4.8) (range, 3-21) and median of 16.0 (interquartile range [IQR], 6.3). The overall modified Helbich MR score showed slightly, not significantly, lower values (Wilcoxon rank sum test and Student t test; P > 0.05): mean (SD) of 14.3 (4.7) (range, 3-20) and median of 15.0 (IQR, 7.3). Without assessment of perfusion, the overall Eichinger score resulted in the following values for CT vs MR examinations: mean (SD), 20.3 (7.2) (range, 4-31); and median, 21.0 (IQR, 9.5) vs mean (SD), 19.5 (7.1) (range, 4-33); and median, 20.0 (IQR, 9.0). All differences between CT and MR examinations were not significant (Wilcoxon rank sum tests and Student t tests; P > 0.05). In general, the correlations of the CT scores (overall and different imaging parameters) to the clinical parameters were slightly higher compared to the MRI scores. However, if all additional MRI parameters were integrated into the scoring systems, the correlations reached the values of the CT scores. The overall image quality was significantly higher for the CT examinations compared to the MRI sequences. CONCLUSIONS One major diagnostic benefit of lung MRI in CF is the possible acquisition of several different morphologic and functional imaging features without the use of any radiation exposure. Lung MRI shows reliable associations with CT and clinical parameters, which suggests its implementation in CF for routine diagnosis, which would be particularly important in follow-up imaging over the long term.
Resumo:
Intrahepatic cholangiocarcinomas are the second most common primary liver malignancies with an increasing incidence over the past decades. Due to a lack of early symptoms and their aggressive oncobiological behavior, the diagnostic approach is challenging and the outcome remains unsatisfactory with a poor prognosis. Thus, a consistent staging system for a comparison between different therapeutic approaches is needed, but independent predictors for worse survival are still controversial. Currently, four different staging systems are primarily used, which differ in the way they determine the 'T' category. Furthermore, different nomograms and prognostic models have been recently proposed and may be helpful in providing additional information for predicting the prognosis and therefore be helpful in approaching an adequate treatment strategy. This review will discuss the diagnostic approach to intrahepatic cholangiocarcinoma as well as compare and contrast the most current staging systems and prognostic models.