SiO<em>_x</em> as a Potential Anode Material for Li-Ion Batteries: Role of Carbon Coating, Doping, and Structural Modifications

Despite the high energy density of SiOx, its practical use as an anode material for Li-ion batteries is hindered by its low electronic conductivity and sluggish electron transport kinetics. These disadvantageous properties result from the insulating nature of SiO2, which leads to electrical contact loss and poor cyclability. Herein, we synthesized a C-SiOx composite based on amorphous carbon and a SiOx matrix via the alcoholysis reaction between SiCl4 and ethylene glycol. We then used nonpolar benzene to simultaneously achieve homogenous dispersion of the Si source and the formation of a carbon coating layer, resulting in the formation of a (C-SiOx)@C composite with exceptional electrochemical properties. Next, we performed structural modifications using Ti doping and a multiple-carbon matrix to successfully fabricate a (C-TixSi1−xOy)@C composite. The combination of Ti doping and carbon coating greatly enhanced the conductivity of SiOx; moreover, the incorporated carbon acted as an effective oxide buffer, preventing structural degradation. The (C-TixSi1−xOy)@C composite exhibited excellent capacity retention of 88.9% over 600 cycles at 1 A g−1 with a capacity of 828 mAh g−1

Clinical characteristics of 2009 pandemic influenza A (H1N1) infection in children and the performance of rapid antigen test

PurposeIn autumn 2009, the swine-origin influenza A (H1N1) virus spread throughout South Korea. The aims of this study were to determine the clinical characteristics of children infected by the 2009 H1N1 influenza A virus, and to compare the rapid antigen and real-time polymerase chain reaction (PCR) tests.MethodsWe conducted a retrospective review of patients ≥18 years of age who presented to Soonchunhyang University Hospital in Seoul with respiratory symptoms, including fever, between September 2009 and January 2010. A real-time PCR test was used to definitively diagnose 2009 H1N1 influenza A infection. Medical records of confirmed cases were reviewed for sex, age, and the time of infection. The decision to perform rapid antigen testing was not influenced by clinical conditions, but by individual factors such as economic conditions. Its sensitivity and specificity were evaluated compared to real-time PCR test results.ResultsIn total, 934 patients tested positive for H1N1 by real-time PCR. The highest number of patients (48.9%) was diagnosed in November. Most patients (48.2%) were aged between 6 and 10 years. Compared with the H1N1 real-time PCR test results, the rapid antigen test showed 22% sensitivity and 83% specificity. Seventy-eight patients were hospitalized for H1N1 influenza A virus infection, and fever was the most common symptom (97.4%).ConclusionFor diagnosis of 2009 H1N1 influenza A virus infection, the rapid antigen test was inferior to the real-time PCR test in both sensitivity and specificity. This outcome suggests that the rapid antigen test is inappropriate for screening

Growth of ultra-uniform graphene using a Ni/W bilayer metal catalyst

We investigated a bilayer catalyst system consisting of polycrystalline Ni and W films for growing mono-layer graphene over large areas. Highly uniform graphene was grown on Ni/W bilayer film with 100% coverage. The graphene grown on Ni/W bilayer film and transferred onto an insulating substrate exhibited average hole and electron mobilities of 727 and 340 cm(2)V(-1)s(-1), respectively. A probable growth mechanism is proposed based on X-ray diffractometry and transmission electron microscopy, which suggests that the reaction between diffused carbon and tungsten atoms results in formation of tungsten carbides. This reaction allows the control of carbon precipitation and prevents the growth of non-uniform multilayer graphene on the Ni surface; this has not been straightforwardly achieved before. These results could be of importance in better understanding mono-layer graphene growth, and suggest a facile fabrication route for electronic applications. (C) 2015 AIP Publishing LLCopen0

Efficient Ruddlesden-Popper Perovskite Light-Emitting Diodes with Randomly Oriented Nanocrystals

Ruddlesden-Popper phase (RP-phase) perovskites that consist of 2D perovskite slabs interleaved with bulky organic ammonium (OA) are favorable for light-emitting diodes (LEDs). The critical limitation of LED applications is that the insulating OA arranged in a preferred orientation limits charge transport. Therefore, the ideal solution is to achieve a randomly connected structure that can improve charge transport without hampering the confinement of the electron-hole pair. Here, a structurally modulated RP-phase metal halide perovskite (MHP), (PEA)(2)(CH3NH3)(m-1)PbmBr3m+1 is introduced to make the randomly oriented RP-phase unit and ensure good connection between them by applying modified nanocrystal pinning, which leads to an increase in the efficiency of perovskite LEDs (PeLEDs). The randomly connected RP-phase MHP forces contact between inorganic layers and thereby yields efficient charge transport and radiative recombination. Combined with an optimal dimensionality, (PEA)(2)(CH3NH3)(2)Pb3Br10, the structurally modulated RP-phase MHP exhibits increased photoluminescence quantum efficiency, from 0.35% to 30.3%, and their PeLEDs show a 2,018 times higher current efficiency (20.18 cd A(-1)) than in the 2D PeLED (0.01 cd A(-1)) and 673 times than in the 3D PeLED (0.03 cd A(-1)) using the same film formation process. This approach provides insight on how to solve the limitation of RP-phase MHP for efficient PeLEDs.

Electrochemical Properties of Chemically Processed SiO

A SiOx coating material for Si anode in lithium-ion battery was processed by using SiCl4 and ethylene glycol. The produced SiOx particles after heat treatment at 725°C for 1 h were porous and irregularly shaped with amorphous structure. Pitch carbon added to SiOx was found to strongly affect solid electrolyte interphase stabilization and cyclic stability. When mixed with an optimal amount of 30 wt% pitch carbon, the SiOx showed a high charge/discharge cyclic stability of about 97% for the 2nd to the 50th cycle. The initial specific capacity of the SiOx was measured to be 1401 mAh/g. On the basis of the evaluation of the SiOx coating material, the process utilized in this study is considered an efficient method to produce SiOx with high performance in an economical way

Comparison of Early and Late Conversion of Sirolimus in Experimental Model of Chronic Cyclosporine Nephropathy

Sirolimus (SRL) is a promising drug for replacing calcineurin inhibitors. We performed this study to determine the optimal time of conversion from cyclosporine (CsA) to SRL in an experimental model of chronic CsA nephropathy. Three separate studies were performed. In the first study, SRL was given to rats with or without CsA for 4 weeks. In the second study, rats were treated initially with CsA for 1 week, and then switched to SRL (early conversion). In the third study, CsA was given for 4 weeks and then replaced by SRL for 4 weeks treatment of CsA (late conversion). The influence of SRL on CsA-induced renal injury was evaluated by assessing renal function, histopathology (interstitial inflammation and fibrosis), and apoptotic cell death. Combined CsA and SRL treatment significantly impaired renal function, increased apoptosis, and interstitial fibrosis and inflammation compared with CsA or SRL treatment alone. Early conversion to SRL did not change renal function, histopathology, or apoptosis compared with early CsA withdrawal. By contrast, late conversion to SRL significantly aggravated these parameters compared with late CsA withdrawal. In conclusion, early conversion from CsA to SRL is effective in preventing CsA-induced renal injury in a setting of CsA-induced renal injury

A Newly Developed Pericardial Tuberculoma During Antituberculous Therapy

Tuberculosis generally affects the respiratory tract. In developing nations, the pericardium is the most common location of extrapulmonary tuberculosis; however, tuberculous pericarditis rarely appears as a localized mass or tuberculoma. We present here a case of a 62-year-old woman with pericardial tuberculoma. She had a history of effusive tuberculous pericarditis and drainage. Because she had taken regular medication over a period of six months, the pericardial mass with an adjacent lung nodule newly detected on the chest radiogram was initially suspected of being invasive lung cancer. Prior to pathologic confirmation, precise information from imaging tests, including computed tomography, magnetic resonance imaging, and positron emission tomography-computed tomography are helpful when making decisions regarding which methods should be used for surgical approach and treatment. Through imaging, our case showed typical features of pericardial tuberculoma and a favorable clinical course after two months with a change in antituberculous therapy