Pressure-induced Anderson-Mott transition in elemental tellurium

AbstractElemental tellurium is a small band-gap semiconductor, which is always p-doped due to the natural occurrence of vacancies. Its chiral non-centrosymmetric structure, characterized by helical chains arranged in a triangular lattice, and the presence of a spin-polarized Fermi surface, render tellurium a promising candidate for future applications. Here, we use a theoretical framework, appropriate for describing the corrections to conductivity from quantum interference effects, to show that a high-quality tellurium single crystal undergoes a quantum phase transition at low temperatures from an Anderson insulator to a correlated disordered metal at around 17 kbar. Such insulator-to-metal transition manifests itself in all measured physical quantities and their critical exponents are consistent with a scenario in which a pressure-induced Lifshitz transition shifts the Fermi level below the mobility edge, paving the way for a genuine Anderson-Mott transition. We conclude that previously puzzling quantum oscillation and transport measurements might be explained by a possible Anderson-Mott ground state and the observed phase transition.</jats:p

Influence of Various Polymorphic Variants of Cytochrome P450 Oxidoreductase (POR) on Drug Metabolic Activity of CYP3A4 and CYP2B6

Cytochrome P450 oxidoreductase (POR) is known as the sole electron donor in the metabolism of drugs by cytochrome P450 (CYP) enzymes in human. However, little is known about the effect of polymorphic variants of POR on drug metabolic activities of CYP3A4 and CYP2B6. In order to better understand the mechanism of the activity of CYPs affected by polymorphic variants of POR, six full-length mutants of POR (e.g., Y181D, A287P, K49N, A115V, S244C and G413S) were designed and then co-expressed with CYP3A4 and CYP2B6 in the baculovirus-Sf9 insect cells to determine their kinetic parameters. Surprisingly, both mutants, Y181D and A287P in POR completely inhibited the CYP3A4 activity with testosterone, while the catalytic activity of CYP2B6 with bupropion was reduced to approximately ∼70% of wild-type activity by Y181D and A287P mutations. In addition, the mutant K49N of POR increased the CLint (Vmax/Km) of CYP3A4 up to more than 31% of wild-type, while it reduced the catalytic efficiency of CYP2B6 to 74% of wild-type. Moreover, CLint values of CYP3A4-POR (A115V, G413S) were increased up to 36% and 65% of wild-type respectively. However, there were no appreciable effects observed by the remaining two mutants of POR (i.e., A115V and G413S) on activities of CYP2B6. In conclusion, the extent to which the catalytic activities of CYP were altered did not only depend on the specific POR mutations but also on the isoforms of different CYP redox partners. Thereby, we proposed that the POR-mutant patients should be carefully monitored for the activity of CYP3A4 and CYP2B6 on the prescribed medication

Total antioxidant activity and trace elements in human milk: the first 4 months of breast-feeding

The content of many nutrients in breast milk are dependent on the nutritional status of the lactating woman. This is particularly true for fat and water-soluble vitamins, some of which have antioxidant properties. The aim of the study entertained herein was to evaluate the changes in total antioxidant status of human milk during the first 4 months of lactation, and to correlate such changes with the contents in specific antioxidant oligoelements (Cu, Zn, Mn and Se). Milk samples were collected from (31) lactating women recruited at the Service of Obstetrics of the Hospital de São João in Porto, after 1, 4, 8, 12 and 16 weeks after birth. The total antioxidant status (TAS) of human milk was measured by the Randox® commercial kit and trace metals by ICP-MS (inductively coupled plasma-mass spectrometry). The results found for TAS and oligoelements under study show a decrease in the concentration of these parameters from 7 days to 4 months of breast-feeding and significant correlations (p < 0.05) were found between TAS and Cu, Zn and Se (not Mn). The decreases of Cu, Zn and Se were also correlated, but not proportional between them, suggesting diverse excretion mechanisms for all. Between primipara and multipara women, a significant difference was found only for Cu and Zn concentrations at 7 days of lactation, but not for the other metals or TAS. With respect to the mother’s age, no correlation was found, either for trace metal concentrations or TAS

Pervasive transition of the Brazilian land-use system

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Motion-Based Design of Semi-Active Tuned Mass Dampers to Control Pedestrian-Induced Vibrations in Footbridges under Uncertainty Conditions

Modern slender footbridges are sensitive to human-induced vibrations together with the uncertainty associated with the variation of the operational and environmental conditions. In order to overcome these limitations, semi-active damping devices have been widely employed due to their adequate balance between their effectiveness and their cost when they are used to control the pedestrian-induced vibrations in footbridges. Different design methods have been proposed to guarantee that the footbridges, controlled by these damping devices, meet the vibration service ability limit state without compromising their budget. Among these proposals, the motion-based design method has shown a high performance when it has been implemented to design passive damping devices for footbridges. Herein, the motion-based design method under uncertainty conditions has been adapted and further implemented for the robust optimum design of semi-active tuned mass dampers when they are employed to control the pedestrian-induced vibrations in slender footbridges. According to this method, the design problem can be transformed into two sub-problems: (i) a multi-objective optimization sub-problem; and (ii) a reliability analysis sub-problem. Thus, its main objective is to find the parameters of the semi-active damping device which guarantee an adequate comfort level without compromising its cost. In order to take into account the effect of the modification of the structural modal properties associated with the variation of the operational and environmental conditions, the compliance of the design requirements has been formulated via a reliability index. Therefore, are liability analysis must be performed to assess the probability of failure associated with the above mentioned serviceability limit state

Motion-Based Design of Active Tuned Mass Dampers to Control Pedestrian-Induced Vibrations in Footbridges under Uncertainty Conditions

Two key aspect must be considered for the design of modern footbridges: (i) their sensitivity to human-induced vibrations; and (ii) the influence of the variation of the operational and environmental conditions on their modal properties. One possible option, to guarantee an adequate behavior of these structures under both conditioning factors, is the installation of a control system. Among the different systems, active damping devices have shown a great effectiveness when they are used to control the dynamic response of civil engineering structures under uncertainty conditions. Different design algorithms have been proposed to guarantee that structures, controlled by these damping devices, meet the design requirements without compromising the budget. Among these proposals, the motion-based design method has shown a high performance when it has been implemented to design passive damping devices for foot-bridges under uncertainty conditions. Herein, this design method has been adapted and further implemented for the robust optimum design of active tuned mass dampers when they are em-ployed to control the human-induced vibrations in slender footbridges. According to this method, the design problem can be transformed into two coupled sub-problems: (i) a multi-objective optimization sub-problem; and (ii) a reliability analysis sub-problem. Thus, the main objective is to find the parameters of the active damping device which guarantee an adequate comfort level without compromising its cost. The compliance of this vibration serviceability limit state is computed via a reliability index (related to the probability of failure), which takes into account the effect of the variation of the operational and environmental conditions on the modal properties of the structure

O processo histórico do trabalho de enfermagem no município de Cuiabá - Mato Grosso El proceso histórico del trabajo de la enfermería en el distrito municipal de Cuiabá-MT The historical process of the nursing work in the city of Cuiabá - Mato Grosso

O estudo trata-se de uma pesquisa histórica, cujo objetivo foi historicizar a singularidade do processo de trabalho de enfermagem no município de Cuiabá/MT. Os dados foram coletados a partir de fontes primárias e secundárias. Pelos dados analisados a enfermagem surgiu com o atendimento e cuidados aos enfermos, prestados por pessoas voluntárias, negros e escravos. A primeira instituição criada foi a Santa Casa de Misericórdia de Cuiabá. A assistência de enfermagem era prestada por religiosas, leigos e escravos, calcados na abnegação, acolhimento e apadrinhamento. Sucessivos eventos importantes como a implantação da ABEn/MT, o Curso de Graduação em Enfermagem e o COREN/MT marcaram a trajetória do trabalho de enfermagem, os quais, estiveram vinculados ao empresariamento na área da saúde no contexto estudado.<br>El estudio se trata de una investigación histórica, cuyo objetivo fue hablar de la historia de la singularidad del proceso de trabajo de enfermería en el municipio de Cuiabá/MT. Los datos se colectaron a partir de fuentes primarias y secundarias. Por los datos analizados la enfermería surgió con la atención y cuidados a los enfermos, prestados por personas voluntarias, negros y esclavos. La primera institución creada fue la Santa Casa de Misericordia de Cuiabá. La asistencia de enfermería era prestada por religiosas, laicos y esclavos, calcados en la abnegación, acogida y apadrinamiento. Sucesivos eventos importantes como la implantación de la ABEn/MT, el Curso de Graduación en Enfermería y el COREN/MT marcaron la trayectoria del trabajo de enfermería, los cuales, estuvieron vinculados al empresariamiento en el área de la salud en el contexto estudiado.<br>The study is a historical research whose aim was to historicize the singularity of the nursing work process in the city of Cuiabá/MT. The data were collected from primary and secondary sources. According to the analyzed data, nursing appeared with the attention and care for the sick, and volunteers, blacks and slaves were the ones who performed it. The first created institution was the Santa Casa de Misericórdia of Cuiabá. The religious, lay people and slaves performed nursing assistance on the basis of abnegation, friendliness, and godfathering. Successive important events such as the implementation of ABEn/MT, the Undergraduate Course in Nursing, and COREN/MT have marked the course of the nursing work, the three of which were linked to the business community in the health sector in the studied context