1,411 research outputs found

    Satlc model lesson for teaching and learning complex environmental issues related to the thermodynamics

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    Environmental chemistry is one of the disciplines of Science. For the goal of the deep learning of the subject, it is indispensable to present perception and models of chemical behaviour explicitly. This can be accomplished by giving careful consideration to the development of concepts such that newer approaches are given contemplation, taking in consideration participation of students. Students, well versed in issues which integrate to enhance vital concepts, are thus able to understand nature and help us to discover means to view the impact of industrialization on the well being of mankind. Understanding environmental chemistry needs quality teaching at undergraduate stage of students learning. In the absence of necessary input of biological sciences, mathematics, statistics, along with the parameters of analytical and physical chemistry, students often find environmental chemistry a difficult subject. It is therefore desirable that the practice of disseminating knowledge related to environmental chemistry must avoid the tradition of presenting the necessary information separated from each other. The lectures should be designed in such a way that they provide the complete description of any issue debated in the class room. The students have not to be encouraged to address the issue in a sphere of limited knowledge. It is suggested that the teachers organize their lectures in such a way that the student get involved in the class. This essential scenario can only develop when the knowledge is transferred through Systemic diagrams. Recently concept based teaching methodology; namely systemic approach to teaching and learning chemistry (SATLC) has been employed to highlight the connectivity between some environmental issues and the disciplines of Physical Chemistry. [African Journal of Chemical Education—AJCE 5(2), July 2015

    Phonon-Induced Rabi-Frequency Renormalization of Optically Driven Single InGaAs/GaAs Quantum Dots

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    The authors thank the EPSRC (U.K.) EP/G001642, and the QIPIRC U.K. for financial support. A. N. is supported by the EPSRC and B.W. L. by the Royal Society.We study optically driven Rabi rotations of a quantum dot exciton transition between 5 and 50 K, and for pulse areas of up to 14 pi. In a high driving field regime, the decay of the Rabi rotations is nonmonotonic, and the period decreases with pulse area and increases with temperature. By comparing the experiments to a weak-coupling model of the exciton-phonon interaction, we demonstrate that the observed renormalization of the Rabi frequency is induced by fluctuations in the bath of longitudinal acoustic phonons, an effect that is a phonon analogy of the Lamb shift.Peer reviewe

    Macrocyclic cyanocobalamin (vitamin B12) as a homogeneous electrocatalyst for water oxidation under neutral conditions

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    Highly water-soluble cyanocobalamin (also known as vitamin B-12) is the most structurally macrocyclic complex comprising cobalt in the center of a corrin ring. Interestingly, it acts as a robust electrocatalyst in water oxidation at similar to 0.58 V overpotential with a faradaic efficiency of 97.50% under neutral buffered conditions. The catalyst is impressively stable even after long-term bulk electrolysis, and homogeneous in nature, as established by a series of experiments and characterization techniques

    Colorectal Cancer Screening Behaviors among American Indians in the Midwest

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    Colorectal cancer is the second most diagnosed cancer among American Indians and is also the second leading cause of cancer death. We used a community-based participatory approach to conduct a mixed methods study to examine colorectal cancer screening behaviors. Here we report on the screening behaviors of our focus group participants (n=153). There were significant gender differences in the colorectal cancer screening rates for FOBT and colonoscopy. Although over 80% of participants reported having health insurance, only 35% of males over 50 years old and 57% of females reported ever having a colonoscopy. More research is needed to identify the causes of gender differences in colorectal cancer screening rates among American Indians. The results of the current study provide new information on the prevalence of colorectal cancer screening among American Indians living in the Midwestern (Kansas and Missouri) portion of the country

    Efficient high-fidelity quantum computation using matter qubits and linear optics

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    We propose a practical, scalable, and efficient scheme for quantum computation using spatially separated matter qubits and single photon interference effects. The qubit systems can be NV-centers in diamond, Pauli-blockade quantum dots with an excess electron or trapped ions with optical transitions, which are each placed in a cavity and subsequently entangled using a double-heralded single-photon detection scheme. The fidelity of the resulting entanglement is extremely robust against the most important errors such as detector loss, spontaneous emission, and mismatch of cavity parameters. We demonstrate how this entangling operation can be used to efficiently generate cluster states of many qubits, which, together with single qubit operations and readout, can be used to implement universal quantum computation. Existing experimental parameters indicate that high fidelity clusters can be generated with a moderate constant overhead.Comment: 5 pages, 3 figures, broader introduction and improved scalability of cluster state generatio

    Long-lived spin entanglement induced by a spatially correlated thermal bath

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    We investigate how two spatially separated qubits coupled to a common heat bath can be entangled by purely dissipative dynamics. We identify a dynamical time scale associated with the lifetime of the dissipatively generated entanglement and show that it can be much longer than either the typical single-qubit decoherence time or the time scale on which a direct exchange interaction can entangle the qubits. We give an approximate analytical expression for the long-time evolution of the qubit concurrence and propose an ion trap scheme in which such dynamics should be observable.Comment: 5 pages, 2 figure

    Life assessment prognostic modelling for multi-layered coating systems using a multidisciplinary approach

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    The multi-disciplinary approach has been adopted to model the formation and propagation of blistering effect for evaluation of useful coating life in the multi-layered coating-substrate system. Prognostic model of de-bonding driving force has been formulated as a function of material science, solid mechanics and fracture mechanics properties to estimate critical, safe and fail conditions of the coating-substrate system. The blister growth velocity rate is also included in the developed model to estimate the blister propagation as a function of diffusion-induced stress and residual stress. The proposed prognostic modelling for the formation and propagation of blistering effect are combined to form an assessment model for evaluation of useful coating life of the multi-layered coating-substrate system and validated through experimental observation

    Selective spin coupling through a single exciton

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    We present a novel scheme for performing a conditional phase gate between two spin qubits in adjacent semiconductor quantum dots through delocalized single exciton states, formed through the inter-dot Foerster interaction. We consider two resonant quantum dots, each containing a single excess conduction band electron whose spin embodies the qubit. We demonstrate that both the two-qubit gate, and arbitrary single-qubit rotations, may be realized to a high fidelity with current semiconductor and laser technology.Comment: 5 pages, 3 figures; published version, equation formatting improved, references adde
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