Investigation into the voltammetric behaviour and detection of selenium(IV) at metal electrodes in diverse electrolyte media

The voltammetric behaviour of selenium(IV) was studied at platinum and gold electrodes in sulphuric acid, perchloric acid and potassium chloride media as a basis for its voltammetric detection. The best voltammetric behaviour was recorded at gold electrodes with perchloric acid as the supporting electrolyte. The concomitant presence of metals, such as copper or lead, and of model biomolecules, such as bovine serum albumin, in the solution resulted in a deterioration of the electrochemical response for selenium(IV). Quantitative detection of selenium(IV) by square wave anodic stripping voltammetry at both a millimetre-sized gold disc electrode and a microband electrode array revealed linear responses to selenium concentration in the ranges of 5-15 μM and 0.1-10 μM, respectively, with 60 s preconcentration. The sensitivities were 6.4 μA μM-1 cm-2 and 100 μA μM-1 cm-2 at the disc and the microband array, respectively. The detection limit at the microband electrode array was 25 nM, illustrating the potentiality of such microelectrodes for the development of mercury-free analytical methods for the trace detection of selenium(IV)

Identifikasi Kompetensi SMK Program Studi Otomotif dalam Rangka Implementasi Kebijakan Kurikulum 2013

The objective of this study was to determine; 1) the relevance of competencies in curriculum 2013 with the expectation of the school and the world of business and industry 2) the competencies expected by the school and the world of business and industry for the development of curriculum 2013, and 3) the roles of lecturers and education experts in the implementation of curriculum 2013, especially for the Department of Automotive, Vocational High Schools in Yogyakarta. The study was conducted with survey approach in the industry (authorized workshops), schools (Vocational High School), and universities (YSU and STU). The data collection was conducted using documentation, questionnaires, and interviews. The data was analysed using quantitative descriptive statistics. The results showed that: the relevance of competencies in curriculum 2013 with the expected competencies was 82% to 89%. The competencies expected by the schools and the world of business and industry consists of drawing with autocad and / or 3D max, spooring, as well as maintaining hidroulik power steering, measuring and analyzing vehicle emissions, maintaining hydraulic power steering (HPS), analyzing damage in the system of wiring diagram, and conducting damage diagnosis. The lectures' contribution in the socialization and implementation aspects were categorized as good with the mean scores of 73 and 39.5 respectively

Framework for classifying logical operators in stabilizer codes

Entanglement, as studied in quantum information science, and non-local quantum correlations, as studied in condensed matter physics, are fundamentally akin to each other. However, their relationship is often hard to quantify due to the lack of a general approach to study both on the same footing. In particular, while entanglement and non-local correlations are properties of states, both arise from symmetries of global operators that commute with the system Hamiltonian. Here, we introduce a framework for completely classifying the local and non-local properties of all such global operators, given the Hamiltonian and a bi-partitioning of the system. This framework is limited to descriptions based on stabilizer quantum codes, but may be generalized. We illustrate the use of this framework to study entanglement and non-local correlations by analyzing global symmetries in topological order, distribution of entanglement and entanglement entropy.Comment: 20 pages, 9 figure

The ground state properties of the spin-1/2 transverse Ising chain with periodically varying bonds and fields

Using continued fractions we study the ground state properties of the spin-1/2 Ising chain in a transverse field with periodically varying interaction strengths and external fields. We consider in detail the chain having the period of modulation of interactions equals 2 and compare the results obtained with those corresponding to the spin-1/2 isotropic XY chain in a transverse field. In contrast to the behaviour of the transverse XY chain, the transverse Ising chain does not exhibit a step-like magnetization vs. field dependence caused by the alternation of bonds, its susceptibility exhibits a logarithmic singularity at the field determined by interaction strengths, and it is stable with respect to spin-Peierls dimerization.Comment: 11 pages, latex, 4 figure

Charge orderings in the atomic limit of the extended Hubbard model

The extended Hubbard model in the atomic limit (AL-EHM) on a square lattice with periodic boundary conditions is studied with use of the Monte Carlo (MC) method. Within the grand canonical ensemble the phase and order-order boundaries for charge orderings are obtained. The phase diagrams include three types of charge ordered phases and the nonordered phase. The system exhibits very rich structure and shows unusual multicritical behavior. In the limiting case of tij = 0, the EHM is equivalent to the pseudospin model with single-ion anisotropy 1/2U, exchange interaction W in an effective magnetic field (mu-1/2U-zW). This classical spin model is analyzed using the MC method for the canonical ensemble. The phase diagram is compared with the known results for the Blume-Capel model.Comment: 9 pages, 10 figure

Combination Rules, Charge Symmetry, and Hall Effect in Cuprates

The rule relating the observed Hall coefficient to the spin and charge responses of the uniform doped Mott insulator is derived. It is essential to include the contribution of holon and spinon three-current correlations to the effective action of the gauge field. In the vicinity of the Mott insulating point the Hall coefficient is holon dominated and weakly temperature dependent. In the vicinity of a point of charge conjugation symmetry the holon contribution to the observed Hall coefficient is small: the Hall coefficient follows the temperature dependence of the diamagnetic susceptibility with a sign determined by the Fermi surface shape. NOTE: document prepared using REVTEX. (3 Figs, not included, available on request from: [email protected])Comment: 8 page

The 16 November 2006 flank collapse of South-East Crater at Mount Etna, Italy: study of the deposit and hazard assessment

On 16 November 2006 a flank collapse affected the unstable Eastern slope of the South-East Crater 16 (SEC) of Mt. Etna. The collapse occurred during one of the paroxysmal events with sustained strombolian 17 activity that characterized the August-December 2006 eruption and was triggered by erosion of loose, 18 hydrothermally-altered material of the steep south-east sector of SEC from the outpour of lava. The collapse 19 produced a debris avalanche that involved both lithic and juvenile material and resulted in a deposit 20 emplaced on the Eastern flank of the volcano up to 1.2 km away from the source. The total volume of the 21 deposit was estimated to be in the order of 330,000-413,000 m3. The reconstruction of the collapse event 22 was simulated using TITAN2D, software designed to model granular avalanches and landslides. This 23 approach can be used to estimate areas that may be affected by similar collapse events in the future. The 24 area affected by the 16 November 2006 lateral collapse of SEC was a small portion of the Mt. Etna summit 25 area, but the fact that no one was killed or injured should be considered fortuitous. The summit and adjacent 26 areas of the volcano, in fact, are usually visited by many tourists who are not prepared to face this type of 27 danger. The 16 November 2006 collapse points to the need to be prepared for similar events through 28 scientific investigation (analysis of flank instability, numerical simulation of flows) and development of specific civil protection plans

Frustration induced Raman scattering in CuGeO_3

We present experimental data for the Raman intensity in the spin-Peierls compound CuGeO_3 and theoretical calculations from a one-dimensional frustrated spin model. The theory is based on (a) exact diagonalization and (b) a recently developed solitonic mean field theory. We find good agreement between the 1D-theory in the homogeneous phase and evidence for a novel dimerization of the Raman operator in the spin-Peierls state. Finally we present evidence for a coupling between the interchain exchange, the spin-Peierls order parameter and the magnetic excitations along the chains.Comment: Phys. Rev. B, Rapid Comm, in Pres