Development of dye-sensitized solar cells based on visible-light-responsive TiO2 thin films with a unique columnar structure

A visible-light-responsive TiO₂ thin film (Vis-TiO₂), possessing a unique columnar structure oriented perpendicular to the substrate, has been prepared by using a radio-frequency magnetron sputtering deposition method. The unique TiO₂ thin film was used as a key component of N719 dye-sensitized solar cells (DSSCs). The rough morphology caused by the columnar structure leads to enhanced photovoltaic performances of these DSSCs as a consequence of increased amounts of adsorbed dyes and facilitated diffusion of the electrolyte into Vis-TiO₂ film. Additionally, photovoltaic performances of the DSSCs were found to depend strongly on the thickness of the Vis-TiO₂ film, which can be readily controlled by adjusting the sputtering time conducted for deposition. Consequently, a solar-to-electric energy conversion efficiency of 2.6 % under AM 1.5 illumination was observed for an optimally performing DSSC that has a Vis-TiO₂ film thickness of 6.9 μm, prepared by employing a sputtering time of 700 min.     

Gold-Catalyzed Regiospecific Annulation of Unsymmetrically Substituted 1,5-Diynes for the Precise Synthesis of Bispentalenes

Precise control of the selectivity in organic synthesis is important to access the desired molecules. We demonstrate a regiospecific annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene derivatives for a geometry-controlled synthesis of linear bispentalenes, which is one of the promising structures for material science. A gold-catalyzed annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene could produce two isomeric pentalenes, but both electronic and steric effects on the aromatics at the terminal position of the alkyne prove to be crucial for the selectivity; especially a regiospecific annulation was achieved with sterically blocked substituents; namely, 2,4,6-trimetyl benzene or 2,4-dimethyl benzene. This approach enables the geometrically controlled synthesis of linear bispentalenes from 1,2,4,5-tetraethynylbenzene or 2,3,6,7-tetraethynylnaphthalene. Moreover, the annulation of a series of tetraynes with a different substitution pattern regioselectively provided the bispentalene scaffolds. A computational study revealed that this is the result of a kinetic control induced by the bulky NHC ligands.     

Efficient and Convenient Protocol for the Synthesis of Novel 1,2,4-Triazolo[3,4-b][1,3,4]Thiadiazines

The novel triazolothiadiazine analogs 5a–p were obtained via a multistep synthetic sequence beginning with 5-substituted 4-amino-1,2,4-triazole-3-thiols 1. Compound 1, in reaction with various aromatic aldehydes 2 in acetic acid, afforded Schiff bases 3a–p. Cyclization of 3a–p with ethyl chloroacetate 4 in the presence of sodium hydride at room temperature gave triazolothiadiazines 5a–p in good yields.     

Cinnamoylphenethyl amides from Polygonum hyrcanicum possess anti-trypanosomal activity

A methanolic extract from aerial parts of Polygonum hyrcanicum (Polygonaceae) showed high activity against Trypanosoma brucei rhodesiense (IC50 = 3.7 microg/mL). Bioassay-guided fractionation of the extract resulted in isolation of cinnamoylphenethyl amides, including N-trans-caffeoyltyramine (1), N-trans-p-coumaroyltyramine (7), and N-trans-feruloyltyramine (8) as the main active constituents (IC50s ranging from 2.2 to 13.3 microM). Some structurally related, but less active compounds, such as cannabisin B (2), tyrosol (3), p-coumaric acid (4), ferulic acid (5), and N-cis-feruloyltyramine (6) were also identified, along with N-trans-3,4-dimethoxycinnamoyldopamine (9). Cytotoxicity of the active compounds in L6 cells was determined, and selectivity indices (SI) of 7.9 to 33.4 were calculated.     

Comparative study on the stabilities and properties of heterodimers containing the intermolecular interactions of CF2Cl2 with the isoelectronic and isostructure species of N2O and CO2

The computational investigations are carried out on the heterodimers containing CF₂Cl₂ with isoelectronic and isostructure (linear triatomics) species of N₂O and CO₂ through MP2/aug-cc-pV(D+d)Z, MP2/aug-cc-pV(T+d)Z//MP2/aug-cc-pV(D+d)Z, and CCSD(T)/aug-cc-pV(D+d)Z//MP2/aug-cc-pV(D+d)Z levels. Five and twelve heterodimers are located on the potential energy surface of CF₂Cl₂–CO₂ and CF₂Cl₂–N₂O systems, respectively. Binding energies of heterodimers in the CF₂Cl₂–CO₂ and CF₂Cl₂–N₂O systems corrected with BSSE are in the ranges of 1.30–5.79 and 1.30–6.85 kJ/mol at the MP2/aug-cc-pV(T+d)Z//MP2/aug-cc-pV(D+d)Z level, respectively. The calculated results reveal that the five most stable heterodimers among all heterodimers obtained for the CF₂Cl₂–CO₂ and CF₂Cl₂–N₂O systems belong to CF₂Cl₂–N₂O system. Therefore, CF₂Cl₂–N₂O system has more key role than CF₂Cl₂–CO₂ one in the atmosphere.     

Propagation of waves in nonlocal porous multi-phase nanocrystalline nanobeams under longitudinal magnetic field

ABSTRACT

This article investigates wave propagation behavior of a multi-phase nanocrystalline nanobeam subjected to a longitudinal magnetic field in the framework of nonlocal couple stress and surface elasticity theories. In this model, the essential measures to describe the real material structure of nanocrystalline nanobeams and the size effects were incorporated. This non-classical nanobeam model contains couple stress effect to capture grains micro-rotations. Moreover, the nonlocal elasticity theory is employed to study the nonlocal and long-range interactions between the particles. The present model can degenerate into the classical model if the nonlocal parameter, couple stress and surface effects are omitted. Hamilton’s principle is employed to derive the governing equations which are solved by applying an analytical method. The frequencies are compared with those of nonlocal and couple stress-based beams. It is showed that wave frequencies and phase velocities of a nanocrystalline nanobeam depend on the grain size, grain rotations, porosities, interface, magnetic field, surface effect and nonlocality.     

Improvement of Thermostability and Activity of Firefly Luciferase Through [TMG][Ac] Ionic Liquid Mediator

Firefly luciferase catalyzes production of light from luciferin in the presence of Mg²⁺?CATP and oxygen. This enzyme has wide range of applications in biotechnology and development of biosensors. The low thermal stability of wild-type firefly luciferase is a limiting factor in most applications. Improvements in activity and stability of few enzymes in the presence of ionic liquids were shown in many reports. In this study, kinetic and thermal stability of firefly luciferase from Photinus pyralis in the presence of three tetramethylguanidine-based ionic liquids was investigated. The enzyme has shown improved activity in the presence of [1, 1, 3, 3-tetramethylguanidine][acetate], but in the presence of [TMG][trichloroacetate] and [TMG][triflouroacetate] activity, it decreased or unchanged significantly. Among these ionic liquids, only [TMG][Ac] has increased the thermal stability of luciferase. Incubation of [TMG][Ac] with firefly luciferase brought about with decrease of K _m for ATP.     

Pulsed laser deposition of Pb(Zr0.52Ti0.48)O3 thin film on cobalt ferrite nano-seed layered Pt(111)/Si substrate: effect of oxygen pressure

The effect of oxygen pressure during pulsed laser deposition of Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films on CoFe₂O₄ nano-seed layered Pt(111)/Si substrate was investigated. The PZT film deposited at oxygen pressure lower than 25 mTorr is identified as both perovskite and pyrochlore phases and the films deposited at high oxygen pressure (50-100 mTorr) show the single-phase perovskite PZT that has a perfect (111)-orientation. In addition, the film deposited at P_O2 of 50 mTorr has a uniform surface morphology, whereas the film deposited at P_O2 of 100 mTorr has a non-uniform surface morphology and more incompacted columnar cross-section microstructure. The polarization of film deposited at 100 mTorr is higher than that deposited at 50 mTorr, but shift of the hysteresis loop along the electrical field axis in the film deposited at P_O2 of 100 mTorr is larger than that of the film deposited at P_O2 of 50 mTorr.     

Influence of atmospheric-air plasma on the coating of a nonionic lubricating agent on polyester fiber

This research work involves the plasma treatment of polyethylene terephthalate fiber to improve the performance of a nonionic lubricating agent. To do this, a polyester fabric was pre-scoured with a detergent, treated with atmospheric-air plasma and then coated with a nonionic emulsion. Chemical and physical properties of the samples were investigated by the use of Fourier transform infrared spectroscopy, bending lengths, wrinkle recovery angles, fiber friction coefficient analysis, moisture absorbency, scanning electron microscopy and reflectance spectroscopy. The study on the chemical properties of the fibers revealed that the plasma pretreatment modifies the surface of the fibers and increases the reactivity of the substrate toward nonionic emulsion. The physical properties of the textiles indicated that the combination of plasma and emulsion treatments on polyester can improve crease resistance, drapeability and water repellency due to a uniform coating of the emulsion on the surface of the textiles.