Novel high birefringence bistolane liquid crystals with lateral fluorosubstituent

Twelve compounds based on lateral fluorinated bistolane moieties with cyano or trifluoromethyl terminal groups were synthesised with Hagihara–Sonogashira cross-coupling reaction. The molecular structures of the compounds were confirmed by Fourier transform infrared, ¹H-nuclear magnetic resonance and mass spectrometry. The transition temperatures, optical textures and optical anisotropies were determined by differential scanning calorimetry, polarizing optical microscopy and ultraviolet microscopy. The effects of the terminal substituents and lateral fluorosubstituent group on their physical properties were investigated and discussed. The compounds with lateral double fluorosubstituent and cyano terminal group exhibited nematogenic texture, while other compounds showed smectic phase. All the compounds exhibited wide liquid crystal temperature ranges and high clearing points. Interestingly, the compounds have the high birefringence in the range of between 0.480 and 0.633.     

Indecomposable representations and boson realizations of the nonlinear deformed angular momentum algebra of Witten’s first type

In this paper indecomposable representations and boson realizations of the nonlinear angular momentum algebra $\mathcal{R}_{q,p}^{c_1,c_2,c_3}$ of Witten’s first type are investigated in a purely algebraic manner. Explicit form of the master representation of $\mathcal{R}_{q,p}^{c_1,c_2,c_3}$ on the space of its universal enveloping algebra is given. Then, from this master representation, other indecomposable representations are obtained in explicit form. Various kinds of single-boson, single inverse boson, and double-boson realizations of $\mathcal{R}_{q,p}^{c_1,c_2,c_3}$ are respectively obtained by generalizing the Holstein–Primakoff realization, the Dyson realization, and the Jordan–Schwinger realization of the Lie algebras SU(2) and SU(1,1). For each kind, the unitary realization, the nonunitary realization, and their connection by the corresponding similarity transformation are respectively discussed. Using a kind of double-boson realizations, the irreducible representation of $\mathcal{R}_{q,p}^{c_1,c_2,c_3}$ in the angular momentum basis is given.     

Dimesogenic compounds with an electron-attracting terminal group

Non-symmetric dimesogens composed of a classical aromatic mesogenic unit linked to a cholesteryl moiety by a flexible spacer form several types of smectic periodicities: one is connected to the cholesteryl length and the other to the length of the associated dimesogens. In some peculiar cases, anomalies of periodicity resulting from the competition between these incommensurate lengths are observed through the occurrence of two-dimensional modulated phases or incommensurate low ordered smectic phases (S_ic). As part of our continuing effort to understand the influence on the smectic arrangement of the molecular parameters of such non-symmetric dimesogens, new homologues with a cholesteryl unit linked by a pentamethylene spacer to an aromatic mesogenic moiety bearing different electron attracting terminal groups have been prepared. For these compounds, only the periodicity resulting from the associated dimesogens is observed. Nevertheless, an incommensurate smectic phase can be induced by mixing one of these compounds with another appropriate dimesogen. Molecular mechanics calculations suggest that the origin of the different smectic structures is strongly connected to the repartition of electrostatic potential along the dimesogen.     

Investigation on ion movement in the fringe-field switching mode depending on resistivity of alignment layer and dielectric anisotropic sign of liquid crystal

Adsorption and desorption of ions at interface between liquid crystal and alignment layer in liquid crystal displays play a crucial role in residual direct current voltage associated with image sticking. In this article, the dependency of such adsorption and desorption of ions on resistivity of alignment layer and sign of liquid crystal dielectric anisotropy in the fringe-field liquid crystal cell has been investigated. Our studies show that the time constant of ions during adsorption and desorption depends upon resistivity and dielectric constant of liquid crystal and alignment layer, and most strongly influenced by the resistivity of alignment layer such that the one with lower resistivity in two orders shows much faster adsorption and desorption at the interface than that of the one with higher resistivity.     

Silaffin Peptides as a Novel Signal Enhancer for Gravimetric Biosensors

Application of biomimetic silica formation to gravimetric biosensors has been conducted for the first time. As a model system, silaffin peptides fused with green fluorescent protein (GFP) were immobilized on a gold quartz crystal resonator for quartz crystal microbalances using a self-assembled monolayer. When a solution of silicic acid was supplied, silica particles were successfully deposited on the Au surface, resulting in a significant change in resonance frequency (i.e., signal enhancement) with the silaffin–GFP. However, frequency was not altered when bare GFP was used as a control. The novel peptide enhancer is advantageous because it can be readily and quantitatively conjugated with sensing proteins using recombinant DNA technology. As a proof of concept, this study shows that the silaffin domains can be employed as a novel and efficient biomolecular signal enhancer for gravimetric biosensors.     

Enhancement of Enzymatic Hydrolysis and Klason Lignin Removal of Corn Stover Using Photocatalyst-Assisted Ammonia Pretreatment

Photocatalyst-assisted ammonia pretreatment was explored to improve lignin removal of the lignocellulosic biomass for effective sugar conversion. Corn stover was treated with 5.0–12.5 wt.% ammonium hydroxide, two different photocatalysts (TiO₂ and ZnO) in the presence of molecular oxygen in a batch reactor at 60 °C. Various solid-to-liquid ratios (1:20–1:50) were also tested. Ammonia pretreatment assisted by TiO₂-catalyzed photo-degradation removed 70 % of Klason lignin under the optimum condition (12.5 % ammonium hydroxide, 60 °C, 24 h, solid/liquid?=?1:20, photocatalyst/biomass?=?1:10 with oxygen atmosphere). The enzymatic digestibilities of pretreated corn stover were 85 % for glucan and 75 % for xylan with NH₃-TiO₂-treated solid and 82 % for glucan and 77 % for xylan with NH₃-ZnO-treated solid with 15 filter paper units/g-glucan of cellulase and 30 cellobiase units/g-glucan of β-glucosidase, a 2–13 % improvement over ammonia pretreatment alone.     

Biological Removal of Phosphate at Low Concentrations Using Recombinant Escherichia coli Expressing Phosphate-Binding Protein in Periplasmic Space

During wastewater treatment, phosphate removal is an important and challenging process; thus, diverse technologies, including those derived from biological means, have been devised for efficient phosphate removal. Although conventional biological methods are effective in decreasing wastewater phosphate levels to ~1 mg/L, long periods of microbial adaptation are required for effective phosphate removal, and the removal efficiency of these methods is relatively poor at lower phosphate concentrations. In the present work, we constructed a recombinant Escherichia coli with periplasmic-expressed phosphate-binding protein (PBP) and investigated its biological removal ability for low phosphate levels. We found that the PBP-expressing recombinant E. coli cells showed efficient (> 94 %) removal of phosphate at low concentrations (0.2–1.0 mg/L) in a treated cell mass-dependent manner. Collectively, we propose that our PBP-expressing recombinant whole-cell system could be successfully used during wastewater treatment for the biological removal of low concentrations of phosphate.     

Glucose Oxidase/Cellulose–Carbon Nanotube Composite Paper as a Biocompatible Bioelectrode for Biofuel Cells

Biofuel cells are devices for generating electrical energy directly from chemical energy of renewable biomass using biocatalysts such as enzymes. Efficient electrical communication between redox enzymes and electrodes is essential for enzymatic biofuel cells. Carbon nanotubes (CNTs) have been recognized as ideal electrode materials because of their high electrical conductivity, large surface area, and inertness. Electrodes consisting entirely of CNTs, which are known as CNT paper, have high surface areas but are typically weak in mechanical strength. In this study, cellulose (CL)–CNT composite paper was fabricated as electrodes for enzymatic biofuel cells. This composite electrode was prepared by vacuum filtration of CNTs followed by reconstitution of cellulose dissolved in ionic liquid, 1-ethyl-3-methylimidazolium acetate. Glucose oxidase (GOx), which is a redox enzyme capable of oxidizing glucose as a renewable fuel using oxygen, was immobilized on the CL–CNT composite paper. Cyclic voltammograms revealed that the GOx/CL–CNT paper electrode showed a pair of well-defined peaks, which agreed well with that of FAD/FADH_2, the redox center of GOx. This result clearly shows that the direct electron transfer (DET) between the GOx and the composite electrode was achieved. However, this DET was dependent on the type of CNTs. It was also found that the GOx immobilized on the composite electrode retained catalytic activity for the oxidation of glucose.     

Cloning, Expression, and Characterization of β-mannanase from Bacillus subtilis MAFIC-S11 in Pichia pastoris

The β-mannanase gene (1,029 nucleotide) from Bacillus subtilis MAFIC-S11, encoding a polypeptide of 342 amino acids, was cloned and expressed in Pichia pastoris. To increase its expression, the β-mannanase gene was optimized for codon usage (mannS) and fused downstream to a sequence-encoding modified α-factor signal peptide. The expression level was improved by 2-fold. This recombinant enzyme (mannS) showed its highest activity of 24,600 U/mL after 144-h fermentation. The optimal temperature and pH of mannS were 50 °C and 6.0, respectively, and its specific activity was 3,706 U/mg. The kinetic parameters V _max and K _m were determined as 20,000 U/mg and 8 mg/mL, respectively, representing the highest ever expression level of β-mannanase reported in P. pastoris. In addition, the enzyme exhibited much higher binding activity to chitin, chitosan, Avicel, and mannan. The superior catalytic properties of mannS suggested great potential as an effective additive in animal feed industry.