The effects of surface treatment combining corona discharge and hydrogen peroxide (H2O2) on the electrochemical performance of carbon felt electrodes for vanadium redox flow batteries (VRFBs) have been thoroughly investigated. A high concentration of oxygen functional groups has been successfully introduced onto the surface of the carbon felt electrodes by a specially designed surface treatment, which is mainly responsible for improving the energy efficiency of VRFBs. In addition, the wettability of the carbon felt electrodes also can be significantly improved. The energy efficiency of the VRFB cell employing the surface modified carbon felt electrodes is improved by 7% at high current density (148 mA cm−2). Such improvement is attributed to the faster charge transfer and better wettability allowed by surface-active oxygen functional groups. Moreover, this method is much more competitive than other surface treatments in terms of processing time, production costs, and electrochemical performance.

A nonaqueous redox-flow battery employing [Co(bpy)3](+/2+) and [Fe(bpy)3](2+/3+) redox couples is proposed for use in large-scale energy-storage applications. We successfully demonstrate a redox-flow battery with a practical operating voltage of over 2.1 V and an energy efficiency of 85% through a rational cell design. By utilizing carbon-coated Ni-FeCrAl and Cu metal foam electrodes, the electrochemical reactivity and stability of the nonaqueous redox-flow battery can be considerably enhanced. Our approach intoduces a more efficient conversion of chemical energy into electrical energy and enhances long-term cell durability. The cell exhibits an outstanding cyclic performance of more than 300 cycles without any significant loss of energy efficiency. Considering the increasing demands for efficient energy storage, our achievement provides insight into a possible development pathway for nonaqueous redox-flow batteries with high energy densities.

Two-arm poly(ethylene oxide) (PEO) fractions with different molecular weights (MWs) have been prepared. For each fraction, both arms have equal lengths of MW = 2300 or 5500. The MWs and molecular weight distributions of two-arm PEOs after fractionation are determined from vapor pressure osmometry, gel permeation chromatography, and light scattering. Compared to linear PEO fractions with similar molecular lengths, the two-arm PEOs can be viewed as linear chains with a well-defined defect at the center of the molecule. Self-diffusion coefficients of the two-arm PEOs are measured and compared with linear PEOs having molecular lengths equivalent to both a single arm and a whole molecule. The crystallization behavior of the PEOs is monitored via wide angle X-ray diffraction, small angle X-ray scattering, and differential scanning calorimetry. Over a wide undercooling range, the two-arm PEO molecules do not appear to recognize the defects at the center of the chains during the initial stage of crystallization. During this stage of crystallization, they form nonintegral folding chain crystals having a fold length longer than the arm length. The defects are recognized only after the initial crystallization and gradually migrate to the lamellar surface through an apparent thinning process. The crystallization kinetics of the two-arm PEOs are significantly slower than those of the linear PEO molecules having a length equivalent to a single arm as well as a combined length of two arms. The melting behavior of the two-arm PEOs is, however, similar to that of linear PEOs which have a length of a single arm. The single lamellar crystal morphology of the two-arm PEOs observed via polarized light microscopy shows the faceting−rounding−refaceting effect with decreasing undercooling. Nevertheless, refaceted single crystals at very low undercoolings have a rectangular shape rather than the hexagonal one generally observed in the linear PEOs. This difference in the single crystal morphology may be caused by a change in the folding directions due to the large defects on the lamellar surfaces.

For lesions of focal DES restenosis, repeat implantation of SES is more effective in reducing late luminal loss and subsequent restenosis rate than cutting balloon angioplasty. For diffuse DES restenosis, implantation of SES or EES is comparably effective in terms of angiographic and clinical outcomes.

Effects of photosensitizers including riboflavin, chlorophyll b, or methylene blue on the stability of daidzein and genistein were studied in model systems by high-performance liquid chromatography (HPLC). Concentration of daidzein and genistein in 80% methanol with riboflavin under light for 7 h was significantly decreased with the apparent 1st-order rate constants of 0.234 and 0.193/h, respectively, (P < 0.05), while those without riboflavin under light did not change significantly (P > 0.05). The stability of isoflavone aglycones in the dark did not change significantly irrespective of the presence of riboflavin (P > 0.05). The concentrations of daidzein and genistein in chlorophyll b or methylene blue model systems under light were not significantly different from those in the dark for 7 h (P > 0.05). Addition of sodium azide increased the stability of daidzein and genistein in riboflavin photosensitization with concentration dependent manner. However, the protective effects of beta-carotene addition on the photodegradation of isoflavones were not high. The stability difference of daidzein and genistein in riboflavin photosensitization may be due to the high reactivity of riboflavin through type I pathway, although singlet oxygen may be involved in part.

PurposeTo evaluate the risk factors for overactive bladder (OAB) in a population aged 40 years and over in the community.Materials and MethodsWe conducted a community-based survey of OAB in a population aged 40 years and over in Guri City and Yangpyeong County, South Korea, by use of the overactive bladder symptom score (OABSS) questionnaire. A total of 926 subjects were included in the final analysis. The definition of OAB was more than 2 points for the urgency score and 3 points for the sum of scores. In addition, the subjects were asked about age, dwelling place, marital status, educational status, behavioral factors (smoking, drinking, etc), and medical history. Categorical variables were analyzed by using the logistic regression model and were adjusted for age by using the logistic regression model.ResultsOverall OAB prevalence was 14.1% (130/926), made up of 49/403 males (12.2%) and 81/523 females (15.5%). OAB prevalence increased with age (p<0.0001). Risk factors for OAB were educational status (age-adjusted p=0.0487), stroke (p=0.0414), osteoporosis (p=0.0208), asthma (p=0.0091), rhinitis (p=0.0008), and cataract. Other factors (dwelling place, marital status, smoking, drinking, hypertension, diabetes, hyperlipidemia, myocardial infarction, angina, tuberculosis, atopic dermatitis, hepatitis B, and depression) were not associated with OAB.ConclusionsThe prevalence of OAB in our study was about 14.1% and the risk factors for OAB were educational status, stroke, osteoporosis, asthma, rhinitis, and cataract. Knowledge of these risk factors may help in the diagnosis and treatment of OAB.

This project aims to design and develop a prototype for an agent that support online collaborative learning. Online collaborative learning, which has emerged as a new form of education in the knowledge‐based society, is regarded as an effective method for improving practical and highly advanced problem‐solving abilities. Collaborative learning involves complicated processes, such as organizing teams, setting common goals, performing tasks, and evaluating the outcome of team activities. Thus, a teacher may have difficulty promoting and evaluating the entire process of collaborative learning, and a system may need to be developed to support it. Therefore, to promote interaction among learners in the process of collaborative learning, this study designed an extensible collaborative learning agent (ECOLA) for an online learning environment.

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