Effect of Mn substitution on the oxidation/adsorption abilities of iron(III) oxyhydroxides

In this study, divalent manganese ions [Mn(II)] were substituted a part of divalent iron ions [Fe(II)] present in Fe oxyhydroxides to prepare novel composites (Mn@Feox). The composites were prepared by (1) simultaneous hydrolysis of Fe(II) and Mn(II), and (2) rapid oxidation with H₂O₂. The resulting Mn@Feox prepared with different molar ratios of Fe and Mn was characterized and evaluated for their abilities to adsorb arsenic species [As(III) and As(V)] in aqueous solution. X-ray diffraction and field emission transmission electron microscope analyses revealed Mn@Feox has a δ-(Fe_1?x, Mn_x)OOH-like structure with their mineralogical properties resembling those of feroxyhyte (δ-FeOOH). The increase in Mn substitution in Mn@Feox enhanced the oxidative ability to oxidize As(III) to As(V), but it decreased the adsorption capacity for both arsenic species. The optimal Mn/Fe molar ratio that could endow oxidation and magnetic capabilities to the composite without significantly compromising As adsorption capability was determined to be 0.1 (0.1Mn@Feox). The adsorption of As(III) on 0.1Mn@Feox was weakly influenced by pH change while As(V) adsorption showed high dependence on pH, achieving nearly complete removal at pH?<?5.7 but gradual decrease at pH?>?5.7. The adsorption kinetics and isotherms of As(III) and As(V) showed good conformity to pseudo-second-order kinetics model and Freundlich model, respectively.     

Bright-Multicolor,Highly Efficient,and Addressable Phosphorescent Organic Light-Emitting Fibers: Toward Wearable Textile Information Displays

Fiber-based light-emitting devices, which can be directly integrated into daily clothes, have emerged as a next-generation display form factor that can provide informational hyper-connections between humans and devices. However, although various approaches have provided advanced wearability, challenges remain for visualizing information, such as high power consumption resulting from high driving voltage and low current efficiency (CE), limited brightness making information difficult to recognize, and lack of addressability for displaying information. Here, a novel fiber-based textile display that can surmount those challenges by successfully introducing phosphorescent organic light-emitting diodes (phOLEDs) based on a dip-coating method and an addressable structure on cylinder-shaped fiber is reported. The fiber phOLEDs exhibit unprecedented optoelectronic performance, including brightness, CE, and driving voltages comparable to those of conventional glass-based OLEDs. Particularly, they show the highest CE values of 16.3, 60.7, and 16.9 cd A^–1 for red, green, and blue, respectively, among results reported thus far. Also, the fiber phOLEDs with an addressable structure implementing independent pixels can be operated by the matrix-addressable scheme. Based on unique deformability which is confirmed by flexibility tests, the performance capabilities, and addressability, letter information can be successfully visualized on daily clothes, demonstrating the potential for realizing truly wearable textile displays.     

Interfacial behavior of polyimide/primer/copper system by preoxidation of the primer

The copolymers of vinyl imidazole (VI) and vinyl trimethoxy silane (VTS) were applied as the corrosion inhibitors and the adhesion promoters for the polyimide/copper system at elevated temperatures. The mol ratios of VI to VTS were 100 : 0, 70 : 30, 30 : 70, and 0 : 100. Preoxidation of the primer was performed to improve the reactivity of the primer on poly(amic acid). A peel test was performed to evaluate the adhesion strength of the polyimide/primer/copper system after heat treatment at 400°C in a nitrogen atmosphere. The effect of the preoxidation of the primer on corrosion protection and adhesion promotion were investigated by Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The adhesion strength of the polyimide/primer/copper system depended on not only the chemical interaction between polyimide and the preoxidized primer, but also the thermal stability of the primer. It showed the highest value when the mol ratio of VI to VTS was 30 : 70. The primer layer reduced or suppressed copper diffusion into the polyimide layer. The degree of corrosion protection by the primer was affected by its thermal stability and its reactivity on copper. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2518–2524, 2000     

Electrical conductivity of graphite/polystyrene composites made from potassium intercalated graphite

Composites between graphite and polystyrene have been synthesized starting from potassium intercalated graphite and styrene vapor. This in situ polymerization process can be used to make electrically conductive composites containing well-dispersed thin graphite sheets. The conductivities of the composites increase as the number of ordered carbon layers increases. With only 10% graphite in a polystyrene matrix, an electrical conductivity up to 1.3 × 10⁻¹ S/cm can be obtained. The key is synthesizing a material with at least four ordered graphite layers (a stage IV complex) separated by polystyrene. This composite shows an improvement in conductivity over a control composite made by radical polymerization of styrene containing the same amount of dispersed graphite which had a conductivity of 5.0 × 10⁻³ S/cm. Characterization of the complexes by powder X-ray diffraction, scanning electron microscopy and electrical conductivity is presented.     

Detection of the effect of environmental toxicants on the synthetic peptide modified neural cell chip

A cell based chip was designed to differentiate and to detect the effects of environmental chemicals on the neurite outgrowth in PC12 cell. To fabricate platform of cell chip, gold surfaces were modified by RGD based synthetic oligopeptide. Nanoscale controlled self-assembled peptide layer was investigated by Atomic Force Microscopy (AFM). On the fabricated cell chip, PC12 cell was immobilized and the differentiation of neurite outgrowth in PC12 cells was done by neurite growth factor (NGF). Differentiation of PC12 cell was confirmed by immunofluorescence study. Further the differentiation and the length of neurite was confirmed by confocal microscopy study. Voltammetry behavior of the neurite induced PC12 and the electrochemical behavior of the environmental toxicants effect on the neurite outgrowth was measured by cyclic voltammetry (CV). Self-assembled layer mediated cell immobilization technique and voltammetric signal analysis system can be applied to construct the neural cell chip for the detection of large number of environmental toxins and various neurotoxicants.     

Prenylated Flavonoids from Cudrania tricuspidata Suppress Lipopolysaccharide-Induced Neuroinflammatory Activities in BV2 Microglial Cells

In Korea and China, Cudrania tricuspidata Bureau (Moraceae) is an important traditional medicinal plant used to treat lumbago, hemoptysis, and contusions. The C. tricuspidata methanol extract suppressed both production of NO and PGE₂ in BV2 microglial cells. Cudraflavanone D (1), isolated from this extract, remarkably suppressed the protein expression of inducible NO synthase and cyclooxygenase-2, and decreased the levels of NO and PGE₂ in BV2 microglial cells exposed to lipopolysaccharide. Cudraflavanone D (1) also decreased IL-6, TNF-α, IL-12, and IL-1β production, blocked nuclear translocation of NF-κB heterodimers (p50 and p65) by interrupting the degradation and phosphorylation of inhibitor of IκB-α, and inhibited NF-κB binding. In addition, cudraflavanone D (1) suppressed the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK pathways. This study indicated that cudraflavanone D (1) can be a potential drug candidate for the cure of neuroinflammation.     

Numerical simulation of the deposition pattern in multiple electrohydrodynamic spraying

The numerical simulation of a deposition pattern produced by multiple electrohydrodynamic spraying with a capillary-extractor-substrate configuration was investigated using a three-dimensional Lagrangian model. The variables that controlled the characteristics of the deposition pattern were the extractor-substrate voltage, the moving speed of nozzles, and the distance between the nozzles. The deposition characteristics, including the spatial distribution and the average thickness distribution, varied considerably as a function of these factors. In particular, the thickness and uniformity of the intervening region of adjacent sprays are important characteristics that affect the nature of the deposition that results from this technique. The results of the numerical simulation of this study show that the thickness of the intervening region gradually decreases compared with the core region of the sprays when the extractor-substrate voltage or the distance between the nozzles increases. As the moving speed of nozzles increases, the average thickness of the deposition pattern decreases. However, the uniformity of the thickness in the intervening region, as well as the extent of the coverage of the deposition, is maintained despite increases in moving speed of nozzles. It is suggested that the electrical self-dispersion effect and the electrical repulsive interaction between adjacent sprays play an important role in determining the characteristics of the spray evolution and deposition patterns for multiple electrohydrodynamic spraying. In addition, an understanding of multiple electrohydrodynamic spraying, as controlled by the factors mentioned above, can improve the prediction of its deposition characteristics.     

Characterization of deposition patterns produced by twin-nozzle electrospray

This paper presents the characteristics of two-nozzle electrospray deposition with a capillary–extractor–substrate configuration. A three-dimensional Lagrangian model was developed to simulate the spray evolution and deposition patterns. The droplet size distribution was not affected by the extractor–substrate voltage; however, spray evolution was found to be influenced considerably by the extractor–substrate voltage. Smaller particles are deposited densely in the outer region of the spray, whereas larger particles are deposited in the core region of the spray due to the size segregation effect. The normalized thickness in the intervening region of adjacent sprays is thinner than in the core region of sprays and gradually decreases as the extractor–substrate voltage increases. The normalized surface number density of deposited particles in the intervening region of adjacent sprays also decreased with the increasing extractor–substrate voltage, whereas the surface number density of them is larger than that in the core regions of sprays at an extractor–substrate voltage below 3 kV. The deposition patterns using a diluted PSL solution and spray visualization were in good agreement with the simulation results. It is suggested that the electrical self-dispersion effect and electrical repulsive interaction between adjacent sprays play an important role in determining the characteristics of the spray evolution and deposition patterns for multiplexed electrospray deposition.     

An Improvement of UMP‐BP Decoding Algorithm Using the Minimum Mean Square Error Linear Estimator

In this paper, we propose the modified uniformly most powerful (UMP) belief‐propagation (BP)‐based decoding algorithm which utilizes multiplicative and additive factors to diminish the errors introduced by the approximation of the soft values given by a previously proposed UMP BP‐based algorithm. This modified UMP BP‐based algorithm shows better performance than that of the normalized UMP BP‐based algorithm, i.e., it has an error performance closer to BP than that of the normalized UMP BP‐based algorithm on the additive white Gaussian noise channel for low density parity check codes. Also, this algorithm has the same complexity in its implementation as the normalized UMP BP‐based algorithm.