Structural effects on the hole mobilities of indenothiophene-embedded homologs

A systematic study of the relationship between the structures and the non-dispersive hole mobilities (up to 10⁻³ cm² V⁻¹ s⁻¹) of a homologous series of amorphous indenothiophene-containing materials is described. The hole mobilities were dependent mainly on the length and rigidity of the π-conjugated backbone and the peripheral substituents.     

Thermally enhanced optical nonlinearity in nematic liquid crystal close to phase transition temperature

This study investigates the beam profile and the liquid crystal (LC) arrangement affected by an optical field on LC thin films at a temperature close to nematic-isotropic phase transition temperature (T_NI). A combined microscopic and conoscopic technique was used in experiments as a convenient way to analyze the optical nonlinearity that is associated with the molecular configuration of nematic liquid crystal (NLC). An optical field combined with thermal enhancement enhances molecular reorientation and causes additional molecular excitation along the axis of propagation of the beam. The reorientational nonlinearity yields an undulating structure with multi-foci; the length between each pair of foci increases with time, as described.     

Generalized projective synchronization of chaotic systems with unknown dead-zone input: observer-based approach

In this paper we investigate the synchronization problem of drive-response chaotic systems with a scalar coupling signal. By using the scalar transmitted signal from the drive chaotic system, an observer-based response chaotic system with dead-zone nonlinear input is designed. An output feedback control technique is derived to achieve generalized projective synchronization between the drive system and the response system. Furthermore, an adaptive control law is established that guarantees generalized projective synchronization without the knowledge of system nonlinearity, and/or system parameters as well as that of parameters in dead-zone input nonlinearity. Two illustrative examples are given to demonstrate the effectiveness of the proposed synchronization scheme.     

Anti-inflammatory constituents from Psychotria prainii H. Lév

One new and three known compounds were isolated from the ethanol extract of Psychotria prainii aerial parts. By means of spectroscopic methods, their structures were elucidated to be deacetylasperulosidic acid 6-ethyl ether (1), asperulosidic acid (2), asperuloside (3) and obtucarbamates C (4). The isolated compounds were evaluated for their inhibitory effect on NO production in LPS-stimulated RAW264.7 cells. Among them, compounds 2 and 4 exhibited strong effect with the IC₅₀ values of 5.75 ± 0.85 and 6.92 ± 0.43 μM, respectively. This is the first report for the chemical composition and biological activity of P. prainii.     

A Hollow Microtubular Triazine‐ and Benzobisoxazole‐Based Covalent Organic Framework Presenting Sponge‐Like Shells That Functions as a High‐Performance Supercapacitor

In this paper we report the construction of a hollow microtubular triazine‐ and benzobisoxazole‐based covalent organic framework (COF) presenting a sponge‐like shell through a template‐free [3+2] condensation of the planar molecules 2,4,6‐tris(4‐formylphenyl)triazine (TPT‐3CHO) and 2,5‐diaminohydroquinone dihydrochloride (DAHQ‐2HCl). The synthesized COF exhibited extremely high crystallinity, a high surface area (ca. 1855 m² g^?1), and ultrahigh thermal stability. Interestingly, a time‐dependent study of the formation of the hollow microtubular COF having a sponge‐like shell revealed a transformation from initial ribbon‐like crystallites into a hollow tubular structure, and confirmed that the hollow nature of the synthesized COF was controlled by inside‐out Ostwald ripening, while the non‐interaction of the crystallites on the outer surface was responsible for the sponge‐like surface of the tubules. This COF exhibited significant supercapacitor performance: a high specific capacitance of 256 F g^?1 at a current density of 0.5 A g^?1, excellent cycling stability (98.8 % capacitance retention over 1850 cycles), and a high energy density of 43 Wh kg^?1. Such hollow structural COFs with sponge‐like shells appear to have great potential for use as high‐performance supercapacitors in energy storage applications.     

Crystal structure of the flagellin protein FlaG from Helicobacter pylori

Flagella, comprising flagellin proteins, are essential virulence factors for Helicobacter pylori to colonize human stomach mucosa. The flagellin‐associated flaG operon of H. pylori consists of the flaG, fliD, and fliS genes under the control of a σ²⁸‐dependent promoter. The flaG gene is involved in chemotaxis and motility. We cloned, expressed, and purified the H. pylori flaG gene encoding the flagellin protein HpFlaG. Sequence alignment revealed that HpFlaG exhibits low sequence identity with other FlaG proteins. Overall, N‐terminal sequences of FlaG proteins are mostly divergent, and C‐terminal regions might be important for dimer interactions between protein subunits. Here, we report the crystal structure of the N‐terminal truncated protein (NT‐HpFlaG), as determined by multiwavelength anomalous dispersion at a resolution of 2.7 å. The overall structure of NT‐HpFlaG consists of two helices and three strands, folded into a palm‐like conformation. Two monomers strongly interact as a dimer by hydrophobic coiled‐coil interactions. Based on our structure, we suggest that the functional state of HpFlaG is as a dimer.     

Development of dipyridine‐based coordinative polymers for reusable heterogeneous catalysts

Poly(di(pyridin‐2‐yl)methyl acrylate) (PDPyMA), which was obtained by the free radical polymerization of designed coordinative monomer of di(pyridin‐2‐yl)methyl acrylate, is able to coordinate with various metal ions to form heterogeneous catalysts for diverse catalytic reactions. The Pd and Cu complexes supported by PDPyMA were developed for the heterogeneous Suzuki‐Miyaura reaction and Friedel‐Crafts alkylation, respectively. The PDPyMA‐based catalysts showed no significant decline of reactivity after five times recycling. However, the hydrolysis of the PDPyMA backbone under alkaline conditions limited the catalytic efficiency of this heterogeneous catalyst so that the coordinative monomer was redesigned as 1,1‐di(pyridine‐2‐yl)‐2‐(4‐vinylphenyl)ethan‐1‐ol and then 2,2′‐(1‐methoxy‐2‐(4‐vinylphenyl)ethane‐1,1‐diyl)dipyridine (MVPhDPy). With copolymerization of N‐isopropyl acrylamide (NIPAM), the efficiency of polymer‐based heterogeneous catalysts could be further raised, demonstrated by the increased turn over number in the Suzuki‐Miyaura reaction, which approached 5,260 by using the catalyst formed from poly(MVPhDPy‐co‐NIPAM) and Pd(OAc)₂. poly(MVPhDPy‐co‐NIPAM) copolymer, therefore, could be a versatile platform to support different metal ions for various heterogeneous catalytic reactions.     

Naphthyridine‐based iridium complexes: Structures and catalytic activity on alkylation of aryl ketones

Iridium(III) complexes containing a designed ligand, 2‐amino‐7‐(2‐pyridinyl)‐1,8‐naphthyridine derivative, were prepared and all complexes were characterized using spectroscopic and crystallographic methods. These new Ir(III) complexes are able to act as catalysts for the C‐alkylation of aryl alkyl ketones with the use of alcohols as the alkylating agent. Typically, acetophenone undergoes alkylation with methanol and ethanol to yield isobutyrophenone and butyrophenone, respectively.     

Acridan‐Grafted Poly(biphenyl germanium) with High Triplet Energy,Low Polarizability,and an External Heavy‐Atom Effect for Highly Efficient Sky‐Blue TADF Electroluminescence

We propose the novel σ–π conjugated polymer poly(biphenyl germanium) grafted with two electron‐donating acridan moieties on the Ge atom for use as the host material in a polymer light‐emitting diode (PLED) with the sky‐blue‐emitting thermally activated delayed fluorescence (TADF) material DMAC‐TRZ as the guest. Its high triplet energy (E_T) of 2.86 eV is significantly higher than those of conventional π–π conjugated polymers (E_T=2.65 eV as the limit) and this guest emitter (E_T=2.77 eV). The TADF emitter emits bluer emission than in other host materials owing to the low orientation polarizability of the germanium‐based polymer host. The Ge atom also provides an external heavy‐atom effect, which increases the rate of reverse intersystem crossing in this TADF guest, so that more triplet excitons are harvested for light emission. The sky‐blue TADF electroluminescence with this host/guest pair gave a record‐high external quantum efficiency of 24.1 % at maximum and 22.8 % at 500 cd m^?2.     

Unparticle Effects on Axion-Like Particles Production in <Emphasis Type="Italic">e</Emphasis><Superscript>+</Superscript><Emphasis Type="Italic">e</Emphasis><Superscript>−</Superscript> Collisions

In this work, we study the effects of the vector unparticle on e⁺e^?→ γa processes. From the numerical results, we show that the cross-section with unparticle effects should be about 10¹⁴ ??10²³ times larger than the one without unparticle effects. This could have important implication for axion like particle searches in near future experiments.