550 research outputs found

    Electrochemical performance of NixCo1-xMoO4 (0 โ‰ค x โ‰ค 1) nanowire anodes for lithium-ion batteries

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    NixCo1-xMoO4 (0 โ‰ค x โ‰ค 1) nanowire electrodes for lithium-ion rechargeable batteries have been synthesized via a hydrothermal method, followed by thermal post-annealing at 500ยฐC for 2 h. The chemical composition of the nanowires was varied, and their morphological features and crystalline structures were characterized using field-emission scanning electron microscopy and X-ray powder diffraction. The reversible capacity of NiMoO4 and Ni0.75Co0.25MoO4 nanowire electrodes was larger (โ‰ˆ520 mA h/g after 20 cycles at a rate of 196 mA/g) than that of the other nanowires. This enhanced electrochemical performance of NixCo1-xMoO4 nanowires with high Ni content was ascribed to their larger surface area and efficient electron transport path facilitated by their one-dimensional nanostructure

    MGOS: A library for molecular geometry and its operating system

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    The geometry of atomic arrangement underpins the structural understanding of molecules in many fields. However, no general framework of mathematical/computational theory for the geometry of atomic arrangement exists. Here we present "Molecular Geometry (MG)'' as a theoretical framework accompanied by "MG Operating System (MGOS)'' which consists of callable functions implementing the MG theory. MG allows researchers to model complicated molecular structure problems in terms of elementary yet standard notions of volume, area, etc. and MGOS frees them from the hard and tedious task of developing/implementing geometric algorithms so that they can focus more on their primary research issues. MG facilitates simpler modeling of molecular structure problems; MGOS functions can be conveniently embedded in application programs for the efficient and accurate solution of geometric queries involving atomic arrangements. The use of MGOS in problems involving spherical entities is akin to the use of math libraries in general purpose programming languages in science and engineering. (C) 2019 The Author(s). Published by Elsevier B.V

    A 1.35GHz All-Digital Fractional-N PLL with Adaptive Loop Gain Controller and Fractional Divider

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    A 1.35GHz all-digital phase-locked loop (ADPLL) with an adaptively controlled loop filter and a 1/3rd-resolution fractional divider is presented. The adaptive loop gain controller (ALGC) effectively reduces the nonlinear characteristics of the bang-bang phase-frequency detector (BBPFD). The fractional divider partially compensates for the input phase error which is caused by the fractional-N frequency synthesis operation. A prototype ADPLL using a BBPFD with a dead zone free retimer, an ALGC, and a fractional divider is fabricated in 0.13m CMOS. The core occupies 0.19mm2 and consumes 13.7mW from a 1.2V supply. The measured RMS jitter was 4.17ps at a 1.35GHz clock output

    Institutional Change and Continuity in Koreas Central Agencies, 1948-2011

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    This article analyzes Koreas central agencies, which have been organized and reorganized to support presidential executive leadership since the foundation of the Republic. Each central agency has carried out the standardization of a core administrative function which is essential to the operation of administrative apparatuses, including policy planning and coordination, budgeting, organizing, staffing, legislation, public relations, central-local relations, control and performance evaluation, etc. The six decades of institutionalization can be characterized, based on the central agencies proportion of the total administrative apparatus, into three phases: high (more than 35 percent, 1948-1961), middle (around 20 percent, 1962-2007), and low (about 10 percent, 2008-present). Regardless of the changing size and organizational configuration of the central agencies, however, their roles and influence as core executive apparatuses have remained largely unchanged, especially since the early 1960s. More than 67 percent, on average, of the heads and deputy heads of CAs have been former public servants, less than 18 percent have been former politicians, and about 15percent have been former outside experts. This strong bureaucratic background has oriented Koreas core executive policy direction significantly toward longterm, consistent, and plan rationality rather than short-term, flexible, and democratic responsiveness

    Absorbable Plate as a Perpendicular Strut for Acute Saddle Nose Deformities

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    BackgroundNasal pyramid fractures accompanied by saddle nose deformities are not easily corrected by closed reduction. We used an absorbable plate as a perpendicular strut to support the collapsed "keystone area" and obtained good results.MethodsBetween September 2008 and June 2011, 18 patients who had nasal pyramid fractures with saddle nose deformities underwent surgery. Pre- and postoperative facial computed tomographic images and photographs were taken to estimate outcomes. The operative technique included the mucoperichondrial dissection of the nasal septum, insertion of an absorbable plate prepared to an appropriate length to support the "keystone area", and fixation of the absorbable plate strut to the cartilaginous septum.ResultsFunctional and esthetic outcomes were satisfactory in all patients. Eleven patients assessed the postoperative appearance of the external nose as 'markedly improved' and 7 patients as 'improved'. The 5 surgeons scored the results as a mean of 4.5 on a 5-point scale.ConclusionsThe use of an absorbable plate as a perpendicular strut requires no additional procedures because the plate is gradually absorbed. The mechanical strength provided by a buttress between the "keystone area" and the maxillary crest lasts for a long time before the strut is absorbed
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