A Stimuli‐Responsive,Photoluminescent, Anthracene‐Based Liquid Crystal: Emission Color Determined by Thermal and Mechanical Processes

Here, a photoluminescent liquid crystal that exhibits a change of emission color on the metastable–stable phase transition induced by external stimuli is prepared. A 2,6‐diethynylanthracene derivative with amide groups and dendritic side chains exhibits a columnar phase on slow cooling from the isotropic phase and shows blue emission in this columnar phase. In contrast, a cubic phase is obtained by rapid cooling from the isotropic phase. In the cubic phase, the 2,6‐diethynylanthracene cores form excimers, resulting in yellow emission. While the columnar phase is a stable liquid‐crystalline (LC) phase, the cubic phase is a metastable LC phase. It is found that a change of the photoluminescent color from yellow to blue is observed on the cubic‐columnar phase transition induced by heating or mechanical shearing for this 2,6‐diethynylanthracene derivative in the cubic phase. This change of photoluminescent color is ascribed to the inhibition of excimer formation on the metastable–stable LC phase transition.     

Placing and imaging individual carbon nanotubes on Cu(111) clean surface using in situ pulsed-jet deposition-STM technique

We report pulsed-jet deposition of single-wall and double-wall carbon nanotubes (SWNTs and DWNTs; CNTs) onto a clean Cu(111) surface and their scanning tunneling microscopy (STM) observations under ultra-high vacuum (UHV). The clean Cu(111) surface prepared by a repeated Ar-sputtering and annealing is introduced into a load-lock chamber kept at a 10(-5)-Pa range vacuum, and the CNTs dispersed in a chloroform solution by ultrasonication are pulse-injected onto the surface. Since the substrate is annealed at 700 K to remove the residual solvent molecules, high resolution lattice images of the CNTs are successfully observed by STM. High-resolution chirality-resolved images of the two SWNTs with a metal cluster are also observed, supporting the well accepted growth mechanism of the CNTs from the metal-catalyst cluster. The present pulsed-jet deposition in high-vacuum is superior to the conventional spin-coating or drop-coating techniques for preparing clean and well-defined CNTs on clean surfaces for high-resolution and contamination-free UHV-STM observation.     

Biohydrogen production from oil palm frond juice and sewage sludge by a metabolically engineered Escherichia coli strain

Biohydrogen is considered a promising and environmentally friendly energy source. Escherichia coli BW25113 hyaB hybC hycA fdoG frdc ldhA aceE has been previously engineered for elevated biohydrogen production from glucose. In this study, we show that this strain can also use biomass from oil palm frond (OPF) juice and sewage sludge as substrates. Substrate improvement was accomplished when hydrogen productivity increased 8-fold after enzymatic treatment of the sludge with a mixture of amylase and cellulase. The OPF juice with sewage sludge provided an optimum carbon/nitrogen ratio since the yield of biohydrogen increased to 1.5 from 1.3 mol H₂/mol glucose compared to our previous study. In this study, we also reveal that our engineered strain improved 200-fold biohydrogen productivity from biomass sources compared to the unmodified host. In conclusion, we determined that our engineered strain can use biomass as an alternative substrate for enhanced biohydrogen production.     

Apatite formation abilities and mechanical properties of hydroxyethylmethacrylate-based organic–inorganic hybrids incorporated with sulfonic groups and calcium ions

Apatite formation in the living body is an essential requirement for artificial materials to exhibit bone-bonding bioactivity. It has been recently revealed that sulfonic groups trigger apatite nucleation in a body environment. Organic–inorganic hybrids consisting of organic polymers and the sulfonic groups are therefore expected to be useful for preparation of novel bone-repairing materials exhibiting flexibility as well as bioactivity. In the present study, organic–inorganic hybrids were prepared from hydroxyethylmethacrylate (HEMA) in the presence of vinylsulfonic acid sodium salt (VSAS) and calcium chloride (CaCl₂). The bioactivities of the hybrids were assessed in vitro by examining the apatite formation in simulated body fluid (SBF, Kokubo solution). The hybrids deposited on the apatite after soaking in SBF within 7 days. Tensile strength measurements showed a tendency to increase with increases in VSAS and CaCl₂ content. It was assumed that this phenomenon was attributed to the formation of cross-linking in the hybrids.     

Synthetic Multifunctional Graphene Composites with Reshaping and Self‐Healing Features via a Facile Biomineralization‐Inspired Process

Since graphene is a type of 2D carbon material with excellent mechanical, electrical, thermal, and optical properties, the efficient preparation of graphene macroscopic assemblies is significant in the potentially large‐scale application of graphene sheets. Conventional preparation methods of graphene macroscopic assemblies need strict conditions, and, once formed, the assemblies cannot be edited, reshaped, or recycled. Herein, inspired by the biomineralization process, a feasible approach of shapeable, multimanipulatable, and recyclable gel‐like composite consisting of graphene oxide/poly(acrylic acid)/amorphous calcium carbonate (GO‐PAA‐ACC) is designed. This GO‐PAA‐ACC material can be facilely synthesized at room temperature with a cross‐linking network structure formed during the preparation process. Remarkably, it is stretchable, malleable, self‐healable, and easy to process in the wet state, but tough and rigid in the dried state. In addition, these two states can be readily switched by adjusting the water content, which shows recyclability and can be used for 3D printing to form varied architectures. Furthermore, GO‐PAA‐ACC can be functionalized or processed to meet a variety of specific application requirements (e.g., energy‐storage, actuators). The preparation method of GO‐PAA‐ACC composite in this work also provides a novel strategy for the versatile macroscopic assembly of other materials, which is low‐cost, efficient, and convenient for broad application.     

Electropolymerization and characterization of terpyridinyl iron (II) and ruthenium (II) complexes

Electroactive 2,2′: 6,2″-terpyridinyl ligands ( 3, 5, 6 ) and their iron(II) ( 7a–9a ) and ruthenium(II) complexes ( 7b–9b ) were synthesized. Bis[3-(aminophenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 7a, 7b ) and bis[2-(hydroxyphenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 8a, 8b ) were electropolymerized on to the surface of Pt or In-SnO₂ (ITO) electrodes in acetonitrile containing Bu₄NCIO₄ by scanning the potential between O and + 1.6V (for 7a and 7b ), and ?0.8 and +1.6V (for 8a and 8b ) versus saturated calomel electrode. The electrodes obtained by electropolymerization exhibited reversible electrochromism based on Fe(II)/Fe(III) or Ru(II)/Ru(III) redox couple. Photoresponses to visible light were found in the modified electrode obtained by electropolymerization of ruthenium complex 7b in an aqueous LiClO₄ solution containing methylviologen (cation MV²⁺) under an O₂ atmosphere. The mechanism for the photoresponded cathodic current was explained in terms of an excitation of bis(terpyridinyl)ruthenium(II) complex [Ru(terpy)²₂⁺] by visible light, an electron transfer from the excited state [Ru(terpy)^2+*₂] to MV²⁺, reduction of Ru(terpy)³⁺₂ at an electrode, and oxidation of MV^+* with O₂.     

High-frequency InP/InGaAs double heterojunction bipolar transistorson Si substrate

Self-aligned high-frequency InP/InGaAs double heterojunction bipolar transistors (DHBTs) have been fabricated on a Si substrate. A current gain of 40 was obtained for a DHBT with an emitter dimension of 1.6 μm×19 μm. The S parameters were measured for various bias points. In the case of I_C=15 mA, f _T was 59 GHz at V_CE=1.8 V, and f _max was 69 GHz at V_CE=2.3 V. Due to the InP collector, breakdown voltage was so high that a V_CE of 3.8 V was applied for I_C=7.5 mA in the S-parameter measurements to give an f_T of 39 GHz and an f_max of 52 GHz     

Functional metallomacrocycle derivatives and their polymers. 31. Preparation and electrochromic properties of novel cobaltophathalocyanine thin films on electrodes

A novel cobaltphthalocyaninanine compound was deposited as a thin film on an indium/tin oxide-coated (ITO) glass electrode by electrodeposition from a solution of 2,9,16,23-tetracarboxyphthalocyaninatocobalto(II) [Co(II)-taPc] and CaCl₂ in DMF. Electrochromic properties of the thin film were investigated. Formation of a calcium chelate complex between Co(II)-taPc and Ca²⁺ and deposition as a thin film on the electrode was confirmed by IR and XMA measurements. Cyclic voltammogram and electron absorption spectra were carried out. Electrochemical reduction and oxidation of CoPc thin films showed a rapid, virtually quantitative reversible process in electrochromism (blue-green-brown). No change in voltammogram was observed after >10,000 cycles.