Development of fast disintegrating compressed tablets using amino acid as disintegration accelerator: evaluation of wetting and disintegration of tablet on the basis of surface free energy

A fast disintegrating compressed tablet was formulated using amino acids, such as L-lysine HCl, L-alanine, glycine and L-tyrosine as disintegration accelerator. The tablets having the hardness of about 4 kgf were prepared and the effect of amino acids on the wetting time and disintegration time in the oral cavity of tablets was examined on the basis of surface free energy of amino acids. The wetting time of the tablets increased in the order of L-lysine HCl, L-alanine, glycine and L-tyrosine, whereas the disintegration time in the oral cavity of the tablets increased in the order of L-alanine, glycine, L-lysine HCl and L-tyrosine. These behaviors were well analyzed by the introduction of surface free energy. When the polar component of amino acid was large value or the dispersion component was small value, faster wetting of tablet was observed. When the dispersion component of amino acid was large value or the dispersion component was small value, faster disintegration of tablet was observed, expect of L-tyrosine tablet. The fast disintegration of tablets was explained by the theory presented by Matsumaru.     

Synthesis of well‐defined block copolymer composed of flexible amphiphilic poly(ethylene glycol) and hydrophobic liquid crystalline segments by living coordination polymerization of allene derivatives and its application to thin film with perpendicularly oriented cylindrical nanostructure

A block copolymer composed of a flexible polar poly(ethylene glycol) (PEG) and a less polar liquid crystalline poly(allene) segments is prepared by the living coordination polymerization of an allene derivative possessing trans‐azobenzene‐containing mesogenic substituent by the use of a π‐allylnickel macroinitiator bearing PEG segment. The thin film of the block copolymer is prepared by the spin coating of its solution onto mica or silicon wafer which proves to possess perpendicularly oriented nanocylindrical microphase separated structures as supported by the differential calorimetric, polarized optical microscopic, grazing‐incidence small‐angle X‐ray scattering, transmission electron microscope, and atomic force microscope measurements.     

Voltammetric Determination of Boric Acid Using the Ternary Complexation System with Salicylaldehyde and H‐Acid

A square‐wave voltammetric method for the determination of boric acid in water has been described based on the new understanding of the electrochemical behavior of boric acid‐Azomethine H complexation. Salicylaldehyde and H‐acid were used as the starting materials of boric acid‐Azomethine H complex and their concentrations were optimized for boric acid determination in water. A glassy carbon electrode, instead of a conventional mercury electrode, was used in the measurement. The detection limit of the proposed method was 0.10 mg B dm^?3. The proposed method was successfully used for boric acid determination in the water from a seawater desalination RO plant.     

Recent progress in bipolar electropolymerization methods toward one-dimensional conducting polymer structures

Recent studies on electropolymerization methods toward one-dimensional conducting polymer structures are summarized in this review. In particular, advanced techniques for templated electropolymerization of aromatic monomers, in which migration of monomers into nanopores of the template is highly enhanced by using electrophoretic effect, are described. For templateless approach, electric field–driven bipolar electropolymerization of 3,4-ethylenedioxythiophene monomer is introduced as a strong tool to fabricate the corresponding conducting polymer fibers and films grown in the direction of an applied electric field.     

Electrochemical Fluorination of Dithiocarbonates Using a Triarylamine Mediator

Electrochemical oxidation of O-(4-chlorobenzyl) S-methyl dithiocarbonate using tris(2,4-dibromophenyl)amine as a redox mediator was studied by cyclic voltammetric measurements. The triarylamine mediated anodic fluorodesulfurization of O-(4-chlorobenzyl) and O-(4-bromobenzyl) S-methyl dithiocarbonates provided 4-chloro- and 4-bromobenzyl fluorides, respectively in moderate yields. On the other hand, similar anodic fluorination of O-(2-phenethyl) S-octyl dithiocarbonate and O-(4-bromophenyl) S-methyl dithiocarbonate afforded 2-phenethyl trifluoromethyl ether and difluoro(methylthio)methyl 4-bromophenyl ether, respectively. Mechanistic aspects are also discussed.     

Electrochemical tuning of the optoelectronic properties of a fluorene-based conjugated polymer

The electrochemical reduction of a fluorene-based conjugated polymer, poly(9-fluorenone-alt-9,9-dioctylfluorene), was investigated for the first time. The carbonyl group in the fluorenone unit was selectively and quantitatively converted to the methylene group, as determined by (1)H NMR, IR, and energy-dispersive X-ray (EDX) analysis. The optical and electrochemical properties of the polymers were studied by UV-vis, photoluminescence (PL), and cyclic voltammetry (CV) measurements and were found to be tunable by varying the reduction level.     

The effect of silica–alumina catalysts on degradation of polyolefins by a continuous flow reactor

Catalytic degradation of polyolefins was performed in a continuous flow reactor that allows the study of the degradation processes at steady state, characterized by constant values of reaction parameters and properties of the products. The continuous flow reactor was operated at atmospheric pressure and at feed rate of 0–1.5 kg h^?1 polyolefins over two silica–alumina catalysts having different SiO₂/Al₂O₃ mole ratio. Polyethylene (PE), polypropylene (PP) and polystyrene (PS) were degraded at 420, 380 and 360 °C respectively. The cracking effect of silica–alumina was proved by the increased amount of gaseous products and by the decreased molecular weight of liquid products. The differences in surface area and in concentration and acidic strength of active centers of the two catalysts affected the distribution of degradation products. Molar rate of degradation was increased in the presence of catalysts, however the mass rate of degradation was decreased leading to higher values of the calculated activation energies. These interesting results might open new perspectives in understanding the macroscopic mechanism for catalytic degradation of polyolefins.     

Influence of particle design on oral absorption of poorly water-soluble drug in a silica particle-supercritical fluid system

The physicochemical characteristics and oral absorption of a poorly water-soluble drug, K-832, adsorbed onto porous silica (Sylysia 350), were compared with those of K-832 adsorbed onto non-porous silica (Aerosil 200). K-832 and silica were treated with supercritical CO(2) (scCO(2)) to produce K-832-Sylysia 350 and K-832-Aerosil 200 formulations. Scanning electron microscopy, polarizing microscopy, powder X-ray diffraction, and differential scanning calorimetry results suggested that K-832 mainly existed in an amorphous state in both formulations. The specific surface area of both formulations was much larger than that of pure K-832 crystals. The dissolution rate of K-832 from both formulations was considerably greater than that from corresponding physical mixtures due to rapid wetting of the hydrophilic carrier surfaces and amorphous state, the dissolution from the K-832-Sylysia 350 formulation being the fastest. In vivo absorption tests on the two formulations indicated no significant differences in their peak concentration (C(max)) and the area under their plasma concentration-time curve (AUC), while the concentrations of K-832 in the K-832-Sylysia 350 formulation were significantly higher than those in the K-832-Aerosil 200 formulation 1 h and 1.5 h after administration of these formulations (p<0.05). This could be attributed to the different dispersion states of K-832 in the formulations due to their different three-dimensional structures (porous and non-porous). In physical stability tests, the amorphous drugs in both formulations were stable at room temperature for at least 14 months. Thus, the absorption of poorly water-soluble drugs could be greatly improved by adsorption onto porous silica using scCO(2).     

Studies on thermal degradation of acrylonitrile–butadiene–styrene copolymer (ABS-Br) containing brominated flame retardant

The thermal degradation of acrylonitrile-butadiene-styrene copolymer (ABS-Br; 10 g) containing brominated flame retardant (Br: 9.59 wt.%) was carried out at 450 °C using a semi batch operation using two different temperature programs. The heating rate was found to affect the quality of the degradation oil and yield of products (liquid, gas and residue). Data on the effect of the temperature program on the accumulation of liquid products was presented. It was found that the majority of the bromine was concentrated in the carbon residue and while majority of the nitrogen accumulates in the liquid products irrespective of degradation mode. The use of a one step constant heating rate process (I) produced a higher liquid yield (39%), than a two step process (29%). Differences were also noted in the Br and N contained in the liquids produced by the two processes.