High‐Precision Temperature‐Controllable Metal‐Coated Polymeric Molds for Programmable,Hierarchical Patterning

Nanofabrication is an indispensable process in nanoscience and nanotechnology. Unconventional lithographic techniques are often used for fabrication as alternatives to photolithography because they are faster, more cost‐effective, and simpler to use. However, these techniques are limited in scalability and utility because of the collapse of preprinted structures during step‐and‐repeat processes. This study proposes a new class of temperature‐controllable polymeric molds that are coated with a metal such that any site‐specific patterning can be accomplished in a programmable manner using selective contact‐dewetting lithography. The lithography allows sub‐100 nm patterning, step‐and‐repeat processing, and hierarchical structure fabrication. The programmable feature of the lithography can be utilized for the structural coloring and shaping of objects. Large‐area programmable patterning, semiconductor device manufacturing, and the fabrication of iridescent security devices would benefit from the unique features of the proposed strategy.     

Improved electrochemical performance of a cyclic ultracapacitor using slurry electrodes under various flow conditions

A cyclic ultracapacitor is a promising energy storage device that can be used for grid energy storage. The cyclic ultracapacitor combines the advantages of both ultracapacitors and flow batteries, enabling rapid charging and large‐scale energy use. To improve the electrochemical performance under the flow condition, it is necessary to find a more electrical active material and design a flow cell that minimizes the resistance. In this study, we investigate the effects of changing the ratio of the active material in a slurry electrode under various operating conditions. Slurry electrodes were prepared with different ratios of active material and conductive additive but with a fixed electrolyte amount. Voltage–time curves of both a single and a stack‐flow cell in the constant‐current mode were obtained to analyze the relationship between the active materials ratio and the cell performance. Having more adsorption sites according to the active material amount is more important than increasing the electric conductivity by the conductive additive amount with regard to cell performance capabilities in a low resistance condition such as a non‐flow mode. However, higher electrical conductivity on a slurry electrode is more beneficial to improve the electrochemical performance in the stack‐flow mode, which has harsh resistance levels. Copyright © 2017 John Wiley & Sons, Ltd.     

Steam reforming of liquefied natural gas (LNG) for hydrogen production over nickel–boron–alumina xerogel catalyst

A series of mesoporous nickel–boron–alumina xerogel (x-NBA) catalysts with different boron/nickel molar ratio (x = 0–1) were prepared by an epoxide-driven sol–gel method. The effect of boron/nickel molar ratio on the catalytic activities and physicochemical properties of nickel–boron–alumina xerogel catalysts was investigated in the steam reforming of liquefied natural gas (LNG). All the mesoporous x-NBA catalysts showed similar surface area. Introduction of boron increased interaction between nickel and support. In addition, introduction of boron into x-NBA catalysts reduced methane activation energy and increased nickel surface area. Promotion of boron had a positive effect on the catalytic activity due to the increase of adsorbed methane and nickel surface area. The amount of adsorbed methane and nickel surface area exhibited volcano-shaped trends with respect to boron/nickel molar ratio. LNG conversion and hydrogen yield increased with increasing the amount of adsorbed methane and with increasing nickel surface area. Among the catalysts, 0.3-NBA, which retained the largest amount of adsorbed methane and the highest nickel surface area, showed the best catalytic performance. It was also revealed that x-NBA catalysts showed strong coke resistance during the steam reforming reaction.     

Rapid and efficient deoxygenation of sulfoxides to sulfides with tantalum(V) chloride/sodium iodide system

TaCl₅/NaI system converts a wide range of sulfoxides to the corresponding sulfides in high yields with short reaction times, under mild conditions. It is worth mentioning that this protocol is chemoselective and tolerates various functional groups (such as –Br, –Cl, –OCH₃, –CHO, and –NO₂) and double bond.     

CO2‐induced crystal engineering of polylactide and the development of a polymeric nacreous microstructure

Nacre's biomineralization process and its self‐organizing brick‐and‐mortar crystalline microstructure have inspired many researchers to develop new materials derived from the natural world. In our study, we took a novel approach to two‐dimensional (2‐D) crystallization. That is, we applied the biomineralization self‐organizational principle that exists in natural materials to a biopolymer (polylactide). The CO₂‐induced crystallization of poly(d ‐lactide), with its unique diffusion‐controlled crystallization mechanism, tends to produce distinct 2‐D spherulitic structures. We found that these 2‐D spherulites were self‐organizing in nature, and that they created a stack of 2‐D spherulitic structures. These crystalline microstructures, with their intervening amorphous phase, were foamed in situ due to the CO₂‐induced crystallization self‐exclusion phenomenon. We compared the resultant crystalline structure with nacre's brick‐and‐mortar crystalline microstructure to confirm the biomimetic principle of self‐organization. To the best of our knowledge, this is the first time that a biopolymer has been crystallized in a 2‐D manner in a way that resembles nature's biomineralization process. The hierarchical crystalline microstructure is morphologically similar to that of nacre biomaterials. This novel crystallization technique is simple, absolutely non‐toxic and works swiftly to produce a brick‐and‐mortar crystalline microstructure with a high degree of order. © 2017 Society of Chemical Industry     

Recent development and challenges of multifunctional structural supercapacitors for automotive industries

In the last decades, fuel scarcity and increasing pollution level pave the way for an extensive interest in alternatives to petroleum‐based fuels such as biodiesel, solar cells, lithium ion batteries, and supercapacitors. Among them, structural supercapacitors have been considered as promising candidates for automotive industries in present time. Herein, the use of carbon fiber‐based supercapacitors in automotive applications is reviewed. Carbon fiber is an excellent candidate for vehicle body applications, and its composites could be widely used in the development of supercapacitors that could provide both structural and energy storage functions. Different surface modification processes of the carbon fiber electrode to enhance the electrochemical as well as mechanical performances are discussed. The advantages of the glass fiber separator and its comparison with other types of dielectric media have been incorporated. The synthesis procedures of the multifunctional solid polymer electrolyte and its significance have been also elaborated. The fabrication process, component selection, limitations, and future challenges of these supercapacitors are briefly assimilated in this review. Copyright © 2017 John Wiley & Sons, Ltd.     

Effects of Color,Scouring Method,and Age on the Visual Sensibility of Naturally Colored Organic Cotton (NaCOC)

In parallel to the social trend of green consumerism and well‐being, the demand for naturally colored organic cotton (NaCOC) continually increases in the textile and clothing industry. The present study examined the effects of NaCOC color, scouring method, and age on the visual sensibility of NaCOC. Two age groups (20s and 30s; 40s and 50s) of women rated three color sets of NaCOC specimens (ivory, green, and coyote brown) treated by two chemical scouring methods (Na₂CO₃ and NaOH) and two bioscouring methods (enzyme and boiling water) using 7‐point scales of nine visual sensibilities (bright‐dark; clear‐murky; heavy‐light; vivid‐subdued; warm‐cool; fresh‐stale; strong‐weak; showy‐plain; and luxurious‐cheap). Preferred scouring methods by NaCOC color and/or age group were recommended for each visual sensibility (e.g., preferred scouring methods for fresh sensibility are Na₂CO₃ for ivory NaCOC, Na₂CO₃ and NaOH for green NaCOC, and boiling water for coyote brown NaCOC). In addition, the representative visual sensibilities of each NaCOC color (e.g., those of coyote brown NaCOC are dark, murky, heavy, vivid, warm, stale, strong, plain, and luxurious sensibilities) were identified for the women participants. Last, it was demonstrated that a bioscouring method can replace the traditional chemical methods for selected visual sensibilities (e.g., boiling water for luxurious sensibility). © 2012 Wiley Periodicals, Inc.     

Korean language math-to-speech rules for digital books for people with reading disabilities and their usability evaluation

The Journal of Supercomputing - Although Digital Accessible Information System, an international digital talking book standard, is conducting active research on upper level education for people...     

Hypoxia Suppresses Spontaneous Mineralization and Osteogenic Differentiation of Mesenchymal Stem Cells via IGFBP3 Up-Regulation

Hypoxia has diverse stimulatory effects on human adipose-derived stem cells (ASCs). In the present study, we investigated whether hypoxic culture conditions (2% O₂) suppress spontaneous mineralization and osteogenic differentiation of ASCs. We also investigated signaling pathways and molecular mechanisms involved in this process. We found that hypoxia suppressed spontaneous mineralization and osteogenic differentiation of ASCs, and up-regulated mRNA and protein expression of Insulin-like growth factor binding proteins (IGFBPs) in ASCs. Although treatment with recombinant IGFBPs did not affect osteogenic differentiation of ASCs, siRNA-mediated inhibition of IGFBP3 attenuated hypoxia-suppressed osteogenic differentiation of ASCs. In contrast, overexpression of IGFBP3 via lentiviral vectors inhibited ASC osteogenic differentiation. These results indicate that hypoxia suppresses spontaneous mineralization and osteogenic differentiation of ASCs via intracellular IGFBP3 up-regulation. We determined that reactive oxygen species (ROS) generation followed by activation of the MAPK and PI3K/Akt pathways play pivotal roles in IGFBP3 expression under hypoxia. For example, ROS scavengers and inhibitors for MAPK and PI3K/Akt pathways attenuated the hypoxia-induced IGFBP3 expression. Inhibition of Elk1 and NF-κB through siRNA transfection also led to down-regulation of IGFBP3 mRNA expression. We next addressed the proliferative potential of ASCs with overexpressed IGFBP3, but IGFBP3 overexpression reduced the proliferation of ASCs. In addition, hypoxia reduced the osteogenic differentiation of bone marrow-derived clonal mesenchymal stem cells. Collectively, our results indicate that hypoxia suppresses the osteogenic differentiation of mesenchymal stem cells via IGFBP3 up-regulation.