Microencapsulation of cholesteryl alkanoate by polymerization‐induced phase separation and its association with drugs

A new microencapsulation technique is presented in which cholesteryl nonanoate (CN)/poly(methyl methacrylate) (PMMA) microcapsules are produced by the induction of phase separation between CN and PMMA within the droplets during the polymerization. The concentration of CN is the most important factor determining the final morphology of the microcapsules. For example, a polynuclear type is obtained at a low concentration (<20 wt %), a mononuclear type is obtained at a medium concentration (20–30 wt %), and an irregular phase is obtained at a high concentration (>40 wt %). To evaluate the effectiveness of the technique for stabilizing an unstable drug, we selected retinol (vitamin A) as a model drug and loaded it into the CN/PMMA microcapsules. We used a process called solute codiffusion, in which a fine solvent emulsion containing the retinol was diffused uniformly into the CN/PMMA microcapsules. The loading efficiency of retinol was predicted successfully with the aid of a thermodynamic equation. In the thermal stability test of retinol, we found that an effective association with the CN phase was the most important factor determining the limit of its molecular stability. The technique reported in this article has great potential for the microencapsulation of soft materials via a simple process and for the stabilization of unstable drugs. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2202–2213, 2004     

Edge domatic numbers of complete n- partite graphs

An edge dominating set of a graph is a set of edgesD such that every edge not inD is adjacent to an edge inD. An edge domatic partition of a graph G =(V, E) is a collection of pairwise disjoint edge dominating sets of G whose union isE. The maximum size of an edge domatic partition of G is called the edge domatic number of G. In this paper we study the edge domatic numbers of completen-partite graphs. In particular, we give exact values for the edge domatic numbers of complete 3-partite graphs and balanced complete n-partite graphs with oddn.     

Synthesis and catalytic properties of barium hexaaluminates incorporated with chromium and lanthanum

Summary Barium hexaaluminates incorporated with chromium and lanthanum (Ba_1-xLa_xCrAl₁₁O_19-a) were synthesized from aqueous metal nitrates and sulfates through the precipitation, and then followed by crystallization at 1300^oC for 2 h. They had the ability to maintain heat resistance and high conversion of CH₄in methane combustion at elevated temperature.     

Cation diffusion in InP/In0.53Ga0.47As superlattices: strain build-up and relaxation

InP and In_0.53Ga_0.47As are lattice matched and can form superlattices that are free of crystalline defects. Zn indiffusion enhances the diffusion of cations while leaving the anions unaffected; the resultant In_1–x Ga _x P/In_1–x Ga _x As superlattices are strained. Since the as-grown specimens are pseudomorphic, any defects observed after Zn diffusion must be attributed to strain relaxation. Studies of the post-growth strain build-up and relaxation in this novel system suggest a new strain relief mechanism for buried strained layers of face-centred-cubic (fcc) structures. The signature defect of the proposed mechanism is a microtwin along a {111} plane spanning the buried strained layer and terminating at both interfaces with partial dislocations of 1/6112 type. Energy analysis indicates that this new partial-dislocation strain relief mechanism is more effective than the conventional 60 perfect-dislocation mechanism for relieving the in-plane strain in buried strained layers. Therefore, the proposed mechanism is an energetically favourable relaxation channel and limits the useful thicknesses of strained layers in electronic and optoelectronic devices.     

Facile CH arylation using catalytically active terminal sulfurs of 2 dimensional molybdenum disulfide

The first methodology of CH arylation of heteroarene via 2D transition metal dichalcogenides that have catalytically active edge functional groups was described. The terminal sulfur groups could effectively catalyze a formation of an azo-linked intermediate with aryl diazonium salts, leading to produce heteroarenes with good yields. This novel methodology using bulk 2D transition metal dichalcogenides that have catalytically active edge functional groups can apply for various reactions to achieve CC bond formation in the fields of heterogeneous catalysis that is easily separable, highly reusable, and inexpensive method.