Volume Ratio Of Ethanol Research Articles

Preparation of lamellar mesoporous silica microspheres via SDS templates

The silica microspheres were prepared by sodium silicate (Na 2O· XSiO 2) and (NH 4) 2SO 4 with sodium dodecyl sulfonate (SDS, C 12H 25SO 3Na) micelles as templates in ethanol–water solvent. The existence of regular arrays of lamellar mesoporous structure was detected by X-ray diffraction (XRD). Then the morphology of SiO 2 microspheres was observed by scanning electron micrograph (SEM). The average diameter of SiO 2 microspheres is 0.2 μm. Content of ethanol, of templates, system temperature and aging time have influence on the formation of the lamellar mesoporous structure. In addition, the best volume ratio of ethanol:water is 1:1.

Development of oral drug delivery system using floating microspheres

Floating acrylic resin microspheres with an internal hollow structure were prepared by a solvent diffusion and evaporation method. The yield of microspheres depended on the diffusion rate of ethanol and/or isopropanol in the organic phase. They were successfully produced when amixture of ethanol and isopropanol was used instead of ethanol alone. The mixing ratioof components in the organic phase affected the size and the yield of microspheres and the best results were obtained at the volume ratio of ethanol:isopropanol:dichloromethane (8:2:5). Direct introduction of the organic phase into the aqueous phase through aglass tube alsosignificantly improved the yield by avoiding the contact of organic phase with the surface of water. The optimum rotation speed and temperature were 250rpm and 25 C, respectively. Several different drugs with various physico-chemical properties were used as model drugs for encapsulation and release tests. When a drug had low solubility in dichloromethaneandhighsolubilityin both water and amixture of ethanol/isopropanol, the loading efficiency was the lowest. The release profiles were significantly different depending on the solubility of a drug in the release medium and the physico-chemical properties of an encapsulated drug.

Penetration of water/ethanol mixtures into silanized silica fibrous assemblies

The penetration rates of water/ethanol mixtures into silica fibrous assemblies were determined from the change in electrical conductivity due to wetting. Silica fibrous assemblies were treated with γ-aminopropyltriethoxysilane (APTES) and methyltriethoxysilane (MTES). The advancing contact angles of the water/ethanol mixtures on silanized silica, a, were measured by the Wilhelmy method. The electrical conductivity, λ, began to increase at time to after the wetting liquid-fibrous assembly contact and reached a constant value. By comparing the experimental λ - t curve with the curve calculated by the Washburn equation, the capillary distribution of the fibrous assembly was determined. The to value as a measure of the penetration rate increased with increasing volume ratio of ethanol in the water/ethanol mixtures for the untreated and APTES-treated silica fibrous assemblies. This indicates that the addition of ethanol to the wetting liquid decreased the penetration rate. In the case of the MTES-treated silica fibrous assembly, liquid penetration was observed above 30% of ethanol and to decreased with increasing volume ratio of ethanol. On the basis of the Washburn equation, the value of 1/t0 was plotted against λL cos a/η, where γL is the surface tension of the liquid and η is the viscosity of the liquid. As expected, the value of 1/t0 increased linearly with increasing cos a/η.

Influence of solvent concentration on the microstructure of SiO2−TiO2 sol-gel films

Spin-coating is one of the possible methodsfor the fabrication of optical planar waveguides. These have several applications in integrated optical devices, provided that their optical losses are below ≈1 dB/cm. The attenuation is caused in part by surface and bulk scattering. The latter depends on the microstructure of the films and, more particularly, the porosity, which is studied here. A series of SiO2−TiO2 films were prepared from solutions containing different concentrations of ethanol. The influence of the ethanol/(Si+Ti)alkoxides volume ratio on the porosity was investigated by Ellipsometry, Infrared Spectroscopy, and Scanning Electron Microscopy. The porosity volume fraction was found to reach a minimum when the ethanol volume ratio is near 4.

Crystal and Molecular Structures of Two Isomers of Phenylglyoxal Bis(amidinohydrazone) [‘Phenylglyoxal Bis(guanylhydrazone)’] Sulphate

The first crystallographic study on an aromatic analogue of the antileukemic agent methylglyoxal bis(amidinohydrazone) (MGBG) is reported. Thus, the crystal and molecular structures of two different geometrical isomers of phenylglyoxal bis(amidinohydrazone) (PhGBG) sulphate were determined by single-crystal X-ray diffraction. Crystals were prepared by recrystallizing PhGBG sulphate using either water or aqueous ethanol (volume ratio ethanol:water 1:4) as the solvent. Depending on the solvent, different types of crystals were obtained although the PhGBG sulphate employed was in the both cases from the same synthesis batch that had been prepared according to classical methods from the corresponding glyoxal. When a crystal obtained from water was studied, PhGBG was found to exist solely in the form of the anti-anti isomer. e. the same isomer that has been observed in the cases of all mono- and dialkylglyoxal bis(amidinohydrazones) so far studied. However, when PhGBG sulphate was recrystallized from 20 % aqueous ethanol, the crystals obtained consisted of a different geometrical isomer. In this anti-syn isomer the carbon-nitrogen double bond closest to the phenyl group had the syn configuration. In the anti-syn isomer, there is an internal hydrogen bond between the two amidinohydrazone moieties, which may markedly contribute to the stabilization of the isomer. The anti-syn isomer of PhGBG is analogous to the only isomer of trifluoromethylglyoxal bis(amidinohydrazone) so far observed. PhGBG sulphate constitutes the first case in which two different geometrical isomers of a bis(amidinohydrazone) have been observed. In the case of the much studied aliphatic mono- and dialkylglyoxal analogues, isomerization of the bis(amidinohydrazone) backbone has never been observed. The structural flexibility of the bis(amidinohydrazone) chain of PhGBG is obviously attributable to the electron-withdrawing resonance effect and perhaps also to the inductive and hyperconjugative effects of the phenyl group. The obviously facile isomerization of PhGBG may markedly influence the biochemical properties of the compound.

Improvement in Androgenetic Alopecia (Stage V) Using Topical Minoxidil in a Retinoid Vehicle and Oral Finasteride

<h3>REPORT OF A CASE</h3> A 32-year-old healthy white man with androgenetic alopecia (AGA)(Hamilton-Norwood stage V) of 10 years' duration presented for therapy (<b>Figure 1</b>). The patient desired to pursue medical treatment only. <h3>THERAPEUTIC CHALLENGE</h3> To optimize the opportunity for hair regrowth in a patient with advanced, extensive AGA using nonsurgical intervention. <h3>SOLUTION</h3> Following informed consent, the patient agreed to a 6to f 2-month trial of topical minoxidil in an optimized retinoid vehicle applied twice per day and 5 mg of finasteride taken orally each day. The topical solution was prepared as follows: minoxidil tablets were dissolved in distilled water, polyethylene glycol, and absolute ethanol (volume ratio, 20:30:50, respectively) to a final minoxidil concentration of 3.75% (grams per deciliter). Following filtration, the 3.75% minoxidil solution was combined with 0.05% tretinoin (4:1 vol/vol) for final concentrations of 3% minoxidil and 0.01% tretinoin. The preparation was stored at room temperature and protected from

Particle adhesion and removal in ethanol/water mixtures

Adhesion and removal of particles to and from substrates were investigated in water, ethanol and ethanol/water mixtures. Spherical polyethylene and nylon particles of 4-5 ,um in diameter were used. Plates of polyethylene, polyvinylidene chloride, polyvinylidene fluoride, polyethylene terephthalate, and nylon 6 were used as substrates. A plate was perpendicularly immersed in the suspension, and the number of particles adhering to the plate was counted using a microscope video system. Since polyvinylidene chloride (PVDC) substrate showed the maximum particle adhesion in water for both kinds of particles, the particle removal experiments were carried out using the PVDC plates. The PVDC plate to which particles in water adhered was immersed in an ethanol/water mixture. The number of particles remaining on the plate was counted, and this determined the particle removal efficiency. The number of adhering particles decreased with increasing volume ratio of ethanol in the ethanol/water mixtures, and only a few particles adhered to all the substrates in the ethanol volume ratio above 30%. The particle removal efficiency increased with increasing volume ratio of ethanol and reached 90% in the ethanol volume ratio above 30%. The experimental results obtained are discussed in terms of electrokinetic potentials, Hamaker constants, and surface free energies. The particle adhesion and removal phenomena were essentially explained in terms of the free energy changes which were estimated from the dispersive and nondispersive surface free energies of the particle, substrate and liquid.