371 research outputs found

    The mechanism of high-T(sub c) superconductivity due to bound hole mediators: Relationship to ferroelectricity

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    The mediation by bound holes creating Cooper pairing in high T(sub c) superconductors has its origin in charge transfer excitations on the multivalence cation (virtual excitions) and in bound excitions or polarizations associated with the oxygen 2p electrons. These phenomena are produced and/or enhanced by a high internal electric field which is itself created by virtue of the unique crystal structures and polyhedral building blocks of high T(sub c) materials. The polarizations which can create oxygen holes (in addition to excitions) may be due to simply the internal electric field or to polaronic and electron-deficient bond behavior. This gives rise to two energy-dependent oxygen bands near the Fermi level. The magnitude and direction of the internal electric fields were calculated for Y1Ba2Cu3O(7-delta) (1-2-3) and show strong z-direction fields at the Cu(2), O2, and O3 sites and an even stronger -z direction field at the O4 site. The field calculations also show why electrical conductivity in the 1-2-3 material is essentially in the base plane of the CuO5 pyramid (the CuO2 plane)

    High Tc superconductors: The scaling of Tc with the number of bound holes associated with charge transfer neutralizing the multivalence cations

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    It is observed that for the known high-T(sub c) Cu-, Tl-, and Bi-based superconductors, T(sub c) scales consistently with the number of bound holes per unit cell which arise from charge transfer excitations of frequency approximately = 3 x 10(exp 13) that neutralized the multivalence cations into diamagnetic states. The resulting holes are established on the oxygens. Extrapolation of this empirical fit in the up-temperature direction suggests a T(sub c) of about 220-230 K at a value of 25 holes/unit cell (approximately the maximum that can be materials-engineered into a high-T(sub c) K2MnF4 or triple Perovskite structure). In the down-temperature direction, the extrapolation gives a T(sub c) in the vicinity of 235 K for the Y-Ba-Cu-O system as well as the known maximum temperature of 23 K for low-T(sub c) materials shown by Nb3Ge. The approach is also consistent with the experimental findings that only multivalence ions which are diamagnetic in their atomic state (Cu, Tl, Bi, Pb, and Sb) associate with high-T(sub c) compounds

    Textile sustainability: reuse of clean waste from the textile and apparel industry

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    Today societies are already experiencing changes in their production systems and even consumption in order to guarantee the survival and well-being of future generations. This fact emerges from the need to adopt a more sustainable posture in both people's daily lives and productive systems. Within this context, textile sustainability emerges as the object of study of this work whose aim is to analyse which sustainability dimensions are being prioritized by the clean waste management systems of the textile and garment industries. This article aims to analyse solutions that are being proposed by sustainable creative business models in the reuse of discarded fabrics by the textile industry. Search also through a qualitative research by a case study (the Reuse Fabric Bank) understand the benefits generated by the re-use in environmental, economic, social and ways to add value.This work is supported by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.info:eu-repo/semantics/publishedVersio

    Demonstration of all‐optical modulation in a vertical guided‐wave nonlinear coupler

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    The performance characteristics of an AlGaAs dual waveguide vertical coupler with a nonlinear GaAs/AlGaAs multiquantum well coupling medium are demonstrated. The structure was grown by molecular beam epitaxy and fabricated by optical lithography and ion milling. The nonlinear coupling and modulation behavior is identical to that predicted theoretically. The nonlinear index of refraction and critical input power are estimated to be n2=1.67×10−5 cm2/W and Pc=170 W/cm2, respectively. This device also allows reliable measurement of the nonlinear refractive index for varying quantum well and optical excitation parameters.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69681/2/APPLAB-52-14-1125-1.pd

    Designing Sustainable Clothing Systems. The design for environmentally sustainable textile clothes and its Product-Service Systems

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    The Fashion System is at the center of the international debate as one of the most polluting and most impactful industries on the environment. In the last decade the fashion industry has changed, and is still modifying, its approach, aware of the fact that the attention to the environment can no longer be considered a trend: the entire system needs to find and adopt a methodological approach to the project and to the production of goods and services. Today all the stakeholders on the supply chain follow a path from upstream to downstream: from the treatment of pollution, to the intervention on the production processes that generate a product, to the redesign of products and/or services to reach the discussion and reorientation of social behavior. This path shows the need to intervene in design terms and that the growth in responsibility and role of design, requiring reference scenarios, knowledge and new tools. The book defines the features and scenarios of sustainable development, as well as the evolution of sustainability in research and practice of fashion design, addressing the strategies for the design and development of environmentally sustainable products. The authors describe the Life Cycle Design approach and the strategies and guidelines for integrating environmental requirements into product design for sustainable fashion. They present the so-called Systems of Sustainable Products-Services, namely the most promising scenarios and models to make design for sustainable fashion economically convenient. Finally, they provide a method and related tools to support design for sustainable fashion in the evaluation of the environmental impact of products, with particular emphasis on the LCA (Life Cycle Assessment). The text is enriched by a full-bodied review of interviews and case studies, with the dual purpose of making the design options clear and of highlighting their specificity for the different design contexts

    New scenarios in secondary hyperparathyroidism: etelcalcetide. Position paper of working group on CKD-MBD of the Italian Society of Nephrology

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    Bone mineral abnormalities (defined as Chronic Kidney Disease Mineral Bone Disorder; CKD-MBD) are prevalent and associated with a substantial risk burden and poor prognosis in CKD population. Several lines of evidence support the notion that a large proportion of patients receiving maintenance dialysis experience a suboptimal biochemical control of CKD-MBD. Although no study has ever demonstrated conclusively that CKD-MBD control is associated with improved survival, an expanding therapeutic armamentarium is available to correct bone mineral abnormalities. In this position paper of Lombardy Nephrologists, a summary of the state of art of CKD-MBD as well as a summary of the unmet clinical needs will be provided. Furthermore, this position paper will focus on the potential and drawbacks of a new injectable calcimimetic, etelcalcetide, a drug available in Italy since few months ago

    New scenarios in secondary hyperparathyroidism: etelcalcetide. Position paper of working group on CKD-MBD of the Italian Society of Nephrology

    Get PDF
    Bone mineral abnormalities (defined as Chronic Kidney Disease Mineral Bone Disorder; CKD-MBD) are prevalent and associated with a substantial risk burden and poor prognosis in CKD population. Several lines of evidence support the notion that a large proportion of patients receiving maintenance dialysis experience a suboptimal biochemical control of CKD-MBD. Although no study has ever demonstrated conclusively that CKD-MBD control is associated with improved survival, an expanding therapeutic armamentarium is available to correct bone mineral abnormalities. In this position paper of Lombardy Nephrologists, a summary of the state of art of CKD-MBD as well as a summary of the unmet clinical needs will be provided. Furthermore, this position paper will focus on the potential and drawbacks of a new injectable calcimimetic, etelcalcetide, a drug available in Italy since few months ago
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