Energy transfer of ionic dyes in mixed surfactant vesicle

Stable vesicles composed of cationic and anionic single-tailed-surfactant were prepared, and their image obtained by electron microscopy with negative staining technique. Significant fluorescence enhancement for acridine orange in vesicle with regards to water has been observed. In heterogeneous vesicle solution composed of mixed cationic and anionic surfactants for the energy transfer between acridine orange (D) and pyronine (A), the Förster dipole-dipole model was valid, and it is interesting to note that the energy transfer rate constant (k_ET) was smaller than that in homogeneous aqueous solution. On the inside and outside of the stable vesicle, immiscible water solution of acridine orange and pyronine could be obtained, and the distance calculated from the energy transfer between D and A separated by the bilayer membrane implied that the location of ionic dye molecules was in the Gouy-Chapman layers of the vesicles. Furthermore, due to the electrostatic absorption of the dye molecules to charged headgroups of surfactants, acridine orange and pyronine accumulated and aggregated to the vesicle bilayer membrane.     

Nonisothermal crystallization kinetics of poly(ε‐caprolactone) blocks in double crystalline triblock copolymers containing poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) and poly(ε‐caprolactone) units

The poly(3‐hydroxbutyrate‐co‐3‐hydroxyvalerate)/poly(ε‐caprolactone) block copolymers (PHCLs) with three different weight ratios of PCL blocks (38%, named PHCL‐38; 53%, named PHCL‐53; and 60%, named PHCL‐60) were synthesized by using PHBV with two hydroxyl end groups to initiate ring‐opening polymerization of ε‐caprolactone. During DSC cooling process, melt crystallization of PHCL‐53 at relatively high cooling rates (9, 12, and 15 °C min^?1) and PHCL‐60 at all the selected cooling rates corresponded to PCL blocks so that PHCL‐53 and PHCL‐60 were used to study the nonisothermal crystallization behaviors of PCL blocks. The kinetics of PCL blocks in PHCL‐53 and PHCL‐60 under nonisothermal crystallization conditions were analyzed by Mo equation. Mo equation was successful in describing the nonisothermal crystallization kinetics of PCL blocks in PHCLs. Crystallization activation energy were estimated using Kissinger's method. The results of kinetic parameters showed that both blocks crystallized more difficultly than corresponding homopolymers. With the increase of PCL content, the crystallization rate of PCL block increased gradually. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Hg-rich liquid-phase epitaxy of Hg1−xCdxTe

Over the past decade, liquid-phase epitaxy (LPE) has become an established technique for the growth of HgCdTe. This article reviews one of the successful LPE technologies developed for HgCdTe, specifically, “infinite-melt” vertical LPE (VLPE) from Hg-rich solutions.

In spite of the relatively low solubility of Cd in Hg-rich solutions and the relatively high Hg pressure at the usual growth temperatures, this approach has been found to offer superior results for growth of HgCdTe suitable for various compositions and layer structures.

An historical perspective and the current status of VLPE technology are presented. Particular emphasis is placed on the important role of the thermodynamic parameters (phase diagram), on control of stoichiometry (defect chemistry) and on impurity doping (distribution coefficient) for growth of HgCdTe layers from Hg solutions. Critical material characteristics, such as transport properties, minority-carrier lifetime, morphology and crystal structure, are also discussed.     

Thermocapillary convection in an absorbing-scattering medium subjected to irradiation

The criteria for the onset of thermocapillary convection in a horizontal radiating fluid layer heated by an incident thermal radiative energy source are determined. The fluid layer is an absorbing and isotropically scattering medium confined between a free upper surface and an insulated rigid lower surface. Linear analysis is performed on the continuity, momentum, energy, and approximate radiative equations. The resulting disturbance equations are solved using a numerical optimization technique to obtain the eigenvalues governing the onset of convective motion. The influence of thermal radiation on the critical Marangoni number is examined. Attention is drawn to the physical significance of the heat transfer mode, gravitational force, the scattering effect, and the surface radiative properties. The conditions leading to the onset of convection are presented as functions of the optical thickness, scattering albedo, Planck number, surface emissivities, and transmissivities.     

Dynamic Inclusion Complexes of Metal Nanoparticles Inside Nanocups

Host–guest inclusion complexes are abundant in molecular systems and of fundamental importance in living organisms. Realizing a colloidal analogue of a molecular dynamic inclusion complex is challenging because inorganic nanoparticles (NPs) with a well‐defined cavity and portal are difficult to synthesize in high yield and with good structural fidelity. Herein, a generic strategy towards the fabrication of dynamic 1:1 inclusion complexes of metal nanoparticles inside oxide nanocups with high yield (>70 %) and regiospecificity (>90 %) by means of a reactive double Janus nanoparticle intermediate is reported. Experimental evidence confirms that the inclusion complexes are formed by a kinetically controlled mechanism involving a delicate interplay between bipolar galvanic corrosion and alloying–dealloying oxidation. Release of the NP guest from the nanocups can be efficiently triggered by an external stimulus.     

Characterization of Novel Aminobenzylcantharidinimides and Related Imides by Proton NMR Spectra and Their Effects on NO Induction

Various acidic anhydrides including cantharidin were converted into corresponding aminobenzylcantharidinimide 3a and analogous imides 3b～k (at the ortho, meta, and para positions) with 35%～87% yields by reacting with aminobenzylamines and triethylamine. The two methyl side chains of cantharidinimides 3ao , 3am , and 3ap, and related imides had more than two chiral centers; the lone pair of electrons of nitrogen displayed a different chemical shift and coupling constant in H‐NMR spectra when the amino group of benzylamine was in the ortho position. These cantharidinimides had parent aniline, pyridine, and naphthalene plane structures, and the primary amine nucleophilicity and basicity might reflect the inductive electron’s negative effect on chemical shifts. We prepared cantharidinimides by heating the reactants cantharidin 1a , aliphatic and aromatic acid anhydrides, primary benzylic amines, and aniline derivatives to ca. 200 °C with 3 mL of dry toluene, and 1～2 mL of triethylamine in high‐pressure sealed tubes (Buchi glasuster 0032) to produce cantharidinimides and their analogues in good yields. The para‐aminobenzylic imides showed greater inhibition of nitric oxide (NO) synthesis by NO synthase (NOS) than did ortho‐ and meta‐aminobenzylic imides. Compound 3fp , para‐aminobenzylic norbonane‐imide, had the most potent effect on inducible NOS among the tested compounds and showed 35% inhibition.