Microencapsulation of TiO2 Nanoparticles with Polymer by Rapid Expansion of Supercritical Solution

A novel preparation method is reported for the microencapsulation of TiO₂ nanoparticles by rapid expansion of supercritical solution with a nonsolvent. A suspension of TiO₂ nanoparticles in carbon dioxide containing a cosolvent and dissolved polymer is sprayed through a nozzle to atmospheric pressure. After rapid expansion, polymer microspheres were obtained. The microspheres do not tend to agglomerate, since the pure cosolvent is a nonsolvent for the polymer. The structure and morphology of microspheres were investigated by SEM, TEM and XRD. The obtained polymer microspheres are microcapsules of TiO₂ nanoparticles. The mean particle diameter and particle size distribution of microcapsules, could be controlled by changing the polymer concentration, pre-expansion pressure, temperature and injection distance. The polymer feed compositions are more effective than other factors on the control of particle size.     

Solution growth of CuGaS2 and CuGaSe2 using CuI solvent

The phase diagrams of the CuGaS₂-CuI and CuGaSe₂-CuI pseudobinary systems are investigated. Both systems show eutectic behavior; liquids along the liquids curves for solute concentrations of more than 15 mol% are shown to be single phase and solids in equilibrium with the liquids are demonstrated to be CuGaS₂ and CuGaSe₂ chalcopyrite compounds. On the basis of the results, bulk crystals of CuGaS₂ and CuGaSe₂ are prepared from CuI solutions using the Bridgman technique. The photoluminescence spectra of these crystals are nearly the same as those of the crystals grown by iodine transport method.     

Distinct difference of chemical behaviors between 5H,7H-dibenzo[b,g][1,5]dithiocin 12-oxide and thiazocine S-oxide

5H, 7H-Diobenzo [b,g] [1,5] dithiocin 12-oxide (2) rearranged into 6-oxide (3) in the presence of CF₃CO₂H. The corresponding thiazocine S-oxide (5) was only protonated at the amino group under the same conditions. Furthermore, methylation of 2 afforded S-methylated product (7) in contrast to O-methylated product in 5.     

Biochemical preparations of both the enantiomers of methyl 3-hydroxypentanoate and their conversion to the enantiomers of 4-hexanolide,the pheromone of trogoderma glabrum1

Both the enantiomers of methyl 3-hydroxypentanoate were prepared by microbial asymmetric reduction of 3-oxopentanoic esters. Conversion of methyl 3-hydroxypentanoate to 4-hexanolide, the pheromone of Trogoderma glabrum, was achieved.     

A novel cyclization reaction of oxidodiazoalkanes: formation of pyrazoles and pyridazines

The thermal decomposition of dialkali metal salts of β- and γ-hydroxyketone tosyl-hydrazones in refluxing DME produced pyrazoles and pyridazines, respectively.     

Selective separation of water–alcohol binary mixture through poly(maleimide-co-acrylonitrile) membrane

Separation of various alcohols and water through a membrane was carried out by means of a hydrogen-bonding interaction. A membrane obtained from poly(maleimide-co-acrylonitrile) was effective for a selective separation of water from aqueous alcohol solution by pervaporation technique. Spectroscopic analyses verified that this high selectivity was attributed to the hydrogen-bonding interaction between water and maleimide units in the membrane.     

Ring-transformation equilibrium with participation of π-bonded S in an isothiazole system. Synthesis of non-ring-transformed 5-(2-aminovinyl)isothiazole derivative via 1,3-silyl group shift

Substituents at 5-position of 5-amino-3-methyl- and 3-p-chlorophenyl-5-methylisothiazoles (7 and 8) were silylated and then lithiated to couple with aromatic nitriles in order to afford the adducts (4 and 5) via 1,3-silyl group shift. Desilylation of 5 with TBAF gave solely non-ring-transformed product (3-α-form). By using the pure sample of 3-α-form, the reversible ring-trans- formation (bond switch) was observed $\text{under neutral conditions}$ for the first time.     

Sigmatropic rearrangements in the allyl substituted oxazolinone system

Thermolysis and photolysis of several allyl substituted oxazolin-5-ones results in a sigmatropic rearrangement in accord with orbital symmetry predictions.