Compatibility and characteristics of poly(butylene succinate) and propylene-co-ethylene copolymer blend

Propylene-co-ethylene elastomer resin (PER) has been blended into biodegradable poly(butylene succinate) copolymer (PBS) by a melt-blending process to develop a novel semi-biodegradable thermoplastic elastomer. The PBS/PER blends displayed good compatibility in the range 70/30 > PBS/PER > 30/70 according to analyses by DSC, DMA and the Couchman method. Although the PBS/PER blends displayed compatibility, SEM analyses of most of the PBS/PER blends revealed two-phase structures including sea-island and irregular fiber-shaped morphologies, except for PBS/PER (70/30). PBS/PER (60/40) and PBS/PER (50/50) display low tensile strength due to large sea-phase and irregular fiber-shaped morphologies, even though they have good compatibility. PBS/PER (70/30) apparently exhibited a single phase by SEM and showed the best compatibility by DSC and DMA. Furthermore, the tan δ, elongation and initial moduli of the PBS/PER blends were seen to increase with increasing PER content, indicating that the toughness and shock resistance of PBS are improved by incorporating PER into the composition.     

Collision-narrowing of Raman spectrum for spin-density fluctuations of electrons in n-GaAs

The inelastic light-scattering spectrum for single-particle excitations in n-GaAs has been found to be considerably $\text{narrower}$ than the Gaussian form usually predicted for a Maxwell-Boltzmann energy distribution. In this paper, we compare the contribution to the narrowing for two factors: collisions and the momentum-dependence of resonant enhancement terms. The analysis is restricted to the spin-density fluctuation mechanism, which has been found to be best suited for probing the electron distribution.     

Thermal degradation of poly(siloxane-urethane) copolymers

The aim of this study was to investigate the characteristics and mechanism of the degradation of poly(siloxane-urethane) (PSiU) copolymers by thermogravimetric analysis (TGA) and TGA coupled with Fourier-transform infra-red spectroscopy (TG-FTIR). The PSiU copolymers consisted of 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (1,4-BD), and OH-terminated polydimethylsiloxane (PDMS). In TGA they exhibited a two-stage degradation at 250-650 °C. The two stages of degradation have been found to comprise eight degradation steps and two interchange reactions, as revealed by TG-FTIR analysis. The main decomposition products have been identified as CO₂, tetrahydrofuran, cyclosiloxane, and macrocyclic species. In addition, the effects of hard segment content (HSC) on the degradation and thermal stability of PSiU copolymers have been investigated by means of TG and DTG curves; notably, a stability region at 410-470 °C is caused by the cyclosiloxane, as verified by TG-FTIR.     

Reaction‐Based and Single Fluorescent Emitter Decorated Ratiometric Nanoprobe to Detect Hydrogen Peroxide

A novel reaction‐based cross‐linked polymeric nanoprobe with a self‐calibrating ratiometric fluorescence readout to selectively detect H₂O₂ is reported. The polymeric nanoprobe is fabricated by using hydrophobic H₂O₂‐reactive boronic ester groups, crosslinker units, and environmentally sensitive 3‐hydroxyflavone fluorophores through a miniemulsion polymerization. On treatment with H₂O₂, the boronic esters in the polymer are cleaved to form hydrophilic alcohols and subsequently lead to a hydrophobic–hydrophilic transition. Covalently linked 3‐hydroxyflavones manifest the change in polarity as a ratiometric transition from green to blue, accompanied by a 500‐fold increase in volume. Furthermore, this nanoprobe has been used for ratiometric sensing of glucose by monitoring the H₂O₂ generated during the oxidation of glucose by glucose oxidase, and thus successfully distinguished between normal and pathological levels of glucose.     

Two theorems of generalized unsynchronization for coupled chaotic systems

Generalized chaos synchronization has been widely studied and many control methods have been presented, but up to now no criterion has been given for generalized unsynchronization. The generalized unsynchronization means that the state variables of two coupled chaotic systems cannot approach generalized synchronization. In this paper, we propose two theorems which give the criteria of generalized unsynchronization for two different chaotic dynamic systems with whatever large strength of linear coupling. Two simulated examples are also given.     

Photoassisted Synthesis of Luminescent Mannose–Au Nanodots for the Detection of Thyroglobulin in Serum

We have employed mannose‐modified gold nanodots (Man–Au NDs) as a luminescence sensor for the detection of the thyroid‐cancer marker thyroglobulin (Tg) in homogeneous solutions. The luminescent Man–Au NDs are prepared through the reaction of 2.9 nm‐diameter gold nanoparticles (Au NPs) with 11‐mercapto‐3,6,9‐trioxaundecyl‐α‐D ‐mannopyranoside (Man‐RSH) under the irradiation of a light‐emitting diode (LED). We have found that the irradiation enhances the quantum yield (～11 %), alters the emission wavelength and lifetimes, and shortens the preparation time. A luminescence assay has been developed for Tg based on the competition between Tg and Man–Au NDs for the interaction with the concanavalin A (Con A). Because luminescence quenching of the Man–Au NDs by Con A is inhibited by Tg selectivity, we have obtained a highly sensitive and selective assay for Tg.     

Experimental and numerical investigations on the dispersion behaviors of wedge waves propagating along wedges with bilinear cross sections

Wedge waves (WW) are guided acoustic waves propagating along the tip of a wedge, with energy tightly confined near the apex. This study is focused on exploring the dispersion behaviors of WW propagating along a bilinear wedge (BW). A BW is wedge with a cross section of two apex angles, compared with a linear wedge (LW) having a single apex angle. In the literature, many studies regarding to the dispersion behaviors of ASF modes are reported for LW, but not for BW. In this study, a combined experimental and numerical stidy is used to investigate the dispersion behavior of WW propagating in BW's. It is found out that WW in a BW is a result of mode coupling between the two WW's corresponding to simple wedges with the two apex angles of the BW.