New complementary electrochromic display utilizing polymeric YbPc2 and Prussian blue films

A new complementary electrochromic display utilizing a plasma polymerized Yb-diphthalo-cyanine (PP-YbPc₂) and Prussian blue (PB) film was fabricated. The PB electrode played the role of a complementary counter electrode for the PP-YbPc₂: it gives rise to a blue-colored state under oxidation. The PP-YbPc₂ electrode changed its color from green to blue by electrochemical reduction. As a result, in a two-electrode cell consisting of the PP-YbPc₂ and PB films, the two colors blue and green were obtained. A three-coloration (blue, green and red) display was fabricated in a three-electrode cell in which a third electrode (i.e. ITO) was electrically connected to the PB electrode. A reduction reaction at the third electrode, as an additional counter electrode, provides adequate oxidation of the PP-YbPc₂ electrode, resulting in the red coloration of the PP-YbPc₂ film.     

Modeling and optimizing a sub-centralized LED lamps provision system for rural communities

Providing clean and sustainable energy for all is an ever elusive challenge, especially encountered in remote and poor rural areas. Cost-effective solutions have been found through renewable energy systems (RES) which, when combined with specialized products like rechargeable lamps using light emitting diodes (LED), can provide the basic energy needs (lighting) of rural homes, while replacing fossil-fuel based energy sources (e.g. kerosene lamps). The investigation presents an LED lamps provision system which circumvents the cost and technical challenges that currently hamper LED lamps diffusion into communities. Based on an actual rural island case (Pangan-an Island, Philippines), a sub-centralized lamp rental and charging system was mathematically modeled and analyzed (analytically and numerically) to identify the optimal states and policies, along with the effects of certain parameters, which promote financial viability and supply sustainability. It was found that a dynamically optimized lamp(s) purchase policy yields better financial returns than a statically optimized policy. Furthermore, it was realized that a sub-centralized lamps rental approach can serve as a complementary energy provision system for rural electrification projects by providing for the lower-tier energy demand market of low income users within a community.     

Characterization of electrical properties and photosensitivity of SnS thin films prepared by the electrochemical deposition method

Using the electrochemical deposition (ECD) method, we prepared tin sulfide thin films, which are suitable for the absorption layer in solar cells because of its bandgap energy (1 eV). We first optimized pulse-form biasing for ECD by characterizing deposited samples with scanning electron microscope, Auger electron spectroscopy and X-ray diffraction measurements. Then, we investigated the electrical properties of deposited SnS thin films and the properties of contacts with several different metals. Furthermore, we observed the photoconductivity of the films by means of photoelectrochemical measurements. From these results, we confirmed that the SnS thin films show p-type conduction.     

Construction of hydrogen fermentation from garbage slurry using the membrane free bioelectrochemical system

The aim of this study was to show the effectiveness of the membrane free bioelectrochemical system (BES) using three electrodes on inhibition of methanogenesis and construction of hydrogen fermentation from the artificial garbage slurry. The electrical redox-potential on the working electrode was adjusted to -1.0V (vs. Ag/AgCl) that has positive effect on methanogenesis. The redox-potential on the counter electrode was measured to be 1.6V. The pH in the effluents was 5.5-6.4. Hydrogen production rate at the cathode side was similar to that at the anode side and much higher than that calculated from current, and reached a maximum of 2445±815 (average±standard deviation) mL?L(-1)?d(-1) at an organic loading rate of 58.7g dichromate chemical oxygen demand per L d(-1). Methane production was negligible throughout the experiment. Acetate and butyrate were the main products of the fermentation using a BES; these offered favorable conditions for hydrogen production. The bacterial community in the bioelectrochemical hydrogen fermentor differed from that in the methanogenic seed sludge and included hitherto unknown species. These results show that high redox-potential on the anodic electrode and acidic pH in the membrane free BES can be utilized for hydrogen fermentation from the artificial garbage slurry by avoiding methanogenesis.     

Ionic conductivity of polymer electrolytes and future applications

Polymer electrolytes are solvent-free ion-conducting polymers and provide new and attractive materials in both polymer chemistry and electrochemistry. A proper understanding of ion dissociation and ion transport in such polymers is necessary for their application as solid electrolytes in electrochemical devices. Ionic conduction behaviour in polymer electrolytes is described here in relation to the characteristic properties. Of special interest is the ability of polymer electrolytes to include various kinds of electroactive molecules within them. The combination of this ability with their high ionic conductivity has enabled polymer electrolytes to be used as media for electrochemical syntheses and redox reactions.     

Preparation and Properties of Low-Calcium–Content Superconductive Thin Films in Bismuth Systems

Superconductive, polycrystalline thin films from Bi systems with low Ca content in relation to the high- T _c phase and with various Bi(Pb) contents were obtained by two-step annealing of the deposited amorphous films prepared by rf magnetron sputtering. The obtained films, A, B, and C, exhibited a high T _c ( T _c > 100 K) for a wide range of secondary annealing temperatures. The critical current densities of these films at 77.3 K in zero magnetic field were sensitive to the secondary annealing temperature. The highest critical current densities of the films were 27000, 3900, and 5500 A/cm² for films A, B, and C, respectively. Film B exhibited large decreases in critical current density under an applied magnetic field. The grain boundaries of this film, which were composed of PbO, CuO, and Bi₂O₃, apparently acted as weak links in the superconductor materials.     

Structure of $$\langle 110 \rangle $$-tilt boundaries in cubic zirconia

Atomic structures of \(\langle 110 \rangle \)-symmetrical tilt grain boundaries in yttria-stabilized cubic zirconia are investigated from a mathematical perspective. We predicted the unique arrangement of structural units along the grain boundaries which was confirmed experimentally by atomic-resolution scanning transmission electron microscopy.     

Direct Evidence of Dopant-Enhanced Grain-Boundary Sliding in Yttria-Stabilized Zirconia Bicrystals

Compression tests were conducted at 1400°C in air for undoped and Si-doped yttria-stabilized zirconia (YSZ) bicrystals with the same orientation relationship (Σ=5, [001]/{210} grain boundary). It was found that the macroscopic grain-boundary slidings are observed during the deformation in both undoped and doped bicrystals, and the sliding displacements increase almost linearly with increasing total displacements. It is distinctly demonstrated that the Si-doped bicrystal exhibits a sliding displacement that is a few times larger than the undoped bicrystal. In addition, the total strain of the Si-doped bicrystal at a failure is much larger than that of the undoped bicrystal. It can be stated that Si doping in YSZ not only enhances the grain-boundary sliding but also suppresses its failure.     

Mechanism for Corrosion Prevention by a Mechanical Plating of Uniform Zinc-Iron Alloy

In situ electrochemical monitoring with a three-electrode cell was applied to investigate the anti-corrosion properties of a mechanical zinc-iron alloy plating. Several electron probe microanalyses were also conducted to identify the chemical elements in the plating. The results indicated the formation of a Zn-Fe intermetallic compound, which allowed a mechanism for corrosion prevention to be proposed. In the proposed mechanism, Zn(OH)₂ plays a significant role in the corrosion prevention of steel alloys.     

Synthesis of polyguanamines from 2-N,N-dibutylamino-4,6-dichloro-1,3,5-triazine with aromatic diamines

Solution polycondensation of 2-N,N-dibutylamino-4,6-dichloro-1,3,5-triazine (BDCT) with various aromatic diamines, including 4,4′-oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), o-tolidine (oTD), 4,4′-(9-fluorenylidene)dianiline (BAFL), and 2,4-diamino-6-(N,N-dibutylamino)-1,3,5-triazine (DABT), was investigated. High molecular weight (>10,000) polyguanamines (PGs) were obtained via the polymerization of BDCT with ODA, pPDA, oTD, and BAFL at 150–180 °C in N-methylpyrrolidone (NMP) for 6 h. The polymerizability with BDCT was determined on the basis of the molecular weights of the polymers and the chemical shifts of the NMR data as follows: ODA > oTD > BAFL > pPDA > mPDA ? DABT. PGs were obtained from the reaction of BDCT with ODA and mPDA in only 55–77% yield, which may be attributed to the formation of cyclic oligomers. All of the polymers showed high thermostability (5% weight-loss temperature in N₂ greater than 444 °C), and the polymers generated from reaction of BDCT with ODA, mPDA, and BAFL exhibited good solubility in tetrahydrofuran and polar aprotic solvents such as NMP.