Thermal conversion of the hydrous aluminosilicate LiAlSiO3(OH)2 into γ-eucryptite

LiAlSiO3(OH)2 is a dense hydrous aluminosilicate which is formed from LiAlSiO4 glass in hydrothermal environments at pressures around 5 GPa. The OH groups are part of the octahedral Al and Li coordination. We studied the dehydration behavior of LiAlSiO3(OH)2 by a combination of TEM and multi-temperature PXRD experiments. Dehydration takes place in the temperature interval 350–400 °C. Above 700 °C LiAlSiO3(OH)2 is converted via a transient and possibly still slightly hydrous phase into γ-eucryptite which is a metastable and rarely observed polymorph of LiAlSiO4. Its monoclinic structure is built from corner-sharing LiO4, AlO4 and SiO4 tetrahedra. The ordered framework of AlO4 and SiO4 tetrahedra is topologically equivalent to that of cristobalite.

Preparation, Characterization, and Stability of the (1-x) CsH2PO4 + xTiO2 Composite Electrolytes for Fuel Cells

Composite Electrolytes (1-x)CsH2PO4/xTiO2(0 ≤ x ≤ 0.4) were prepared and analyzed the structural, thermal, and transport properties. We have investigated the ionic conductivity of the composites electrolyte highly pressurized pellets and found that the conductivity of pure CsH2PO4 (CDP) increased three orders of magnitude at the transition temperature. The conductivity value of the composites is greater than pure CDP after 250°C. Arrhenius plots have confirmed the conductive nature of ionic conduction. The dehydration behavior and thermal stability of the materials were observed in terms of differential scanning calorimetry, thermogravimetric analysis and differential thermal analysis, and found that the minimum weight loss for the composite 0.6CDP/0.4TiO2. The electrodes were prepared with the technique of vapor deposition.

Hydration/Dehydration Behavior of Hydroxyethyl Cellulose Ether in Aqueous Solution

Hydroxyethyl cellulose (HeC) maintains high water solubility over a wide temperature range even in a high temperature region where other nonionic chemically modified cellulose ethers, such as methyl cellulose (MC) and hydroxypropylmethyl cellulose (HpMC), demonstrate cloud points. In order to clarify the reason for the high solubility of HeC, the temperature dependence of the hydration number per glucopyranose unit, nH, for the HeC samples was examined by using extremely high frequency dielectric spectrum measuring techniques up to 50 GHz over a temperature range from 10 to 70 °C. HeC samples with a molar substitution number (MS) per glucopyranose unit by hydroxyethyl groups ranging from 1.3 to 3.6 were examined in this study. All HeC samples dissolve into water over the examined temperature range and did not show their cloud points. The value of nH for the HeC sample possessing the MS of 1.3 was 14 at 20 °C and decreased gently with increasing temperature and declined to 10 at 70 °C. The nH values of the HeC samples are substantially larger than the minimum critical nH value of ca. 5 necessary to be dissolved into water for cellulose ethers such as MC and HpMC, even in a high temperature range. Then, the HeC molecules possess water solubility over the wide temperature range. The temperature dependence of nH for the HeC samples and triethyleneglycol, which is a model compound for substitution groups of HeC, is gentle and they are similar to each other. This observation strongly suggests that the hydration/dehydration behavior of the HeC samples was essentially controlled by that of their substitution groups.

Elucidation of the Crystal Structures and Dehydration Behaviors of Ondansetron Salts

In drug development, it is extremely important to evaluate the solubility and stability of solid states and to immediately determine the potential for development. Salt screening is a standard and useful method for obtaining drug candidates with good solid state properties. Ondansetron is marketed as a hydrochloride dihydrate, and its dehydration behavior was previously reported to transition to an anhydrate via a hemihydrate as an intermediate by heating. Here, we synthesized ondansetron hydrobromide and hydroiodide and examined their dehydration behaviors. Single-crystal structure analysis confirmed that like ondansetron hydrochloride, ondansetron hydrobromide formed a dihydrate. Moreover, the crystal lattice parameters and hydrogen bonding networks were similar and isomorphic. While single-crystal structure analysis showed that ondansetron hydroiodide also formed a dihydrate, the crystal lattice parameters and hydrogen bonding networks were different to those of ondansetron hydrobromide and hydrochloride. Additionally, the dehydration behavior of ondansetron hydrobromide differed from that of the hydrochloride, with no hemihydrate intermediate forming from the hydrobromide, despite similar anhydrate structures. Given that it is difficult to predict how a crystal structure will form and the resulting physical properties, a large amount of data is needed for the rational design of salt optimization.

Thin layer drying of zucchini in solar dryer located in Osmaniye region

In this study, the dehydration behavior of zucchini using solar assisted drying system was examined according to 22 thin layer drying models available in literature. The correlation coefficient (R2), chi-square (χ2) and root mean square error (RMSE) values were calculated to check the suitability of models by non-linear regression analysis. It was found that Cubic and Modified Midilli-1 models were the most suitable equations and their R2 values were calculated as 0.99963. χ2 and RMSE values of related mathematical expressions were 1.89343×10‒5, 1.91692×10‒5 and 0.01685×10‒3, 0.01721×10‒3 respectively. In addition, heat transfer, mass transfer and diffusion coefficients, which were important parameters in design of drying systems were also determined as 5.18124 W/m2°C, 1.57129×10‒7 m/s and 2.335718×10‒9 m2/s respectively.