Stability study of the gastric floating dosage form of capecitabine

Since administration of capecitabine tablets leading to dose limiting makes the unfavorable toxicity, preparation of sustained-release tablets will overcome most of these side effects. The aim of this study was to prepare and study the stability of capecitabine sustained-release tablets. Sustained-release tablets of capecitabine were characterized by differential scanning calorimetry, X-ray diffraction, and infrared and ultraviolet spectroscopy techniques to determine the stability of the tablets. All tests carried out for tablets upon preparation as well as 6 and 12 months after preparation. The gradual decomposition of capecitabine sustained-release tablets stored at accelerated conditions (40 °C in 75 % of relative humidity) was indicated by decreasing values of peak purity and melting temperature, calculated from the Van’t Hoff equation. Except for the occurrence of one sharp peak for long-term stability and some sharp peaks in the accelerated condition, all peaks showed a crystallized nature. But the FTIR and UV results showed that there were no changes between the initial sustained-release tablets and stored tablets. Although the XRD results showed more peaks in the accelerated condition tablets, the crystalline form of capecitabine was maintained. These findings demonstrate that the capecitabine sustained-release tablet has excellent stability in normal and long-term storage conditions, with slight changes in the accelerated condition.     

An accurate empirical correlation for predicting natural gas compressibility factors

The compressibility factor of natural gas is an important parameter in many gas and petroleum engineering calculations. This study presents a new empirical model for quick calculation of natural gas compressibility factors. The model was derived from 5844 experimental data of compressibility factors for a range of pseudo reduced pressures from 0.01 to 15 and pseudo reduced temperatures from 1 to 3. The accuracy of the new empirical correlation has been compared with commonly used existing methods. The comparison indicates the superiority of the new empirical model over the other methods used to calculate compressibility factor of natural gas with average absolute relative deviation percent (AARD%) of 0.6535.     

二氧化钛纳米粒子催化合成Hantzsch酯和多氢喹啉衍生物(英文)

1,4-Dihydropyridine and polyhydroquinoline derivatives have been prepared efficiently in a one-pot synthesis via Hantzsch condensation using nanosized titanium dioxide as a heterogeneous catalyst.The present methodology offers several advantages such as excellent yields,short reaction times (30-120 min),environmentally benign,and mild reaction conditions.The catalyst can be readily separated from the reaction products and recovered in excellent purity for direct reuse.     

Exact three-dimensional interface stress and electrode-effect analysis of multilayer piezoelectric transducers under torsion

In this paper, exact three-dimensional analysis for torsion of multilayer piezoelectric transducers is presented to highlight the remarkable effects of electrode and size effects on interface stresses and deformation. A generalized formulation is introduced for torsion of an arbitrarily layered cross section. In order to reach an advanced and better device, multilayer piezoelectric materials with different properties are formulated while axis of torsion and the polarization axes of each layer make different orientations with respect to each other. An exact formulation for n-layer piezoelectric device with rectangular cross section is presented to compensate considerable deviation of previous studies’ results from exact solution due to the assumption of linear distribution for the electric potential. In order to improve the performance of the transducers, being utilized in industry, several case studies are presented in order to investigate the influence of different parameters, e.g. thickness and material properties of electrodes over shear and peel stresses. Besides, a correction factor is introduced to completely compensate the effect of ignoring electrodes.     

Acrylic-based asymmetric and variable coupling ratio Y-branch plastic optical fiber coupler

Acrylic-based asymmetric and variable couplers have been developed using a single structured Y-branch design with a high-index-contrast waveguide taper and a void structure for fiber attenuation using the lateral displacement of two fibers. Device fabrication is performed by producing the device structure on an acrylic block using a computer numerical control (CNC) machine tool. The fabricated device has an excess loss of 5.85 dB, while the coupling ratios are 56.86 and 43.14% when the device is operated as a 3 dB coupler. In the asymmetric coupler mode, the coupling ratio ranges from 44.84 to 8.01% for port 1 and 55.16 to 91.99% for port 2. The excess loss of this device varies from 5.42 to 7.64 dB. In the variable coupler mode, the coupling ratio ranges from 10.09 to 32.88% for port 1 and from 89.91 to 67.12% for port 2. The excess loss of the device varies from 5.85 to 8.49 dB.     

How Does Tempering Affect the Local and Global Properties of Fractional Brownian Motion?

Journal of Theoretical Probability - The present paper investigates the effects of tempering the power law kernel of the moving average representation of a fractional Brownian motion (fBm) on some...     

Benzene-1,3,5-tricarboxylic acid-functionalized MCM-41 as a novel and recoverable hybrid catalyst for expeditious and efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones via one-pot three-component reaction

Research on Chemical Intermediates - Benzene-1,3,5-tricarboxylic acid-functionalized MCM-41 (MCM-41-Pr-BTA), as a novel hybrid organosilica, was prepared and properly characterized by the...     

Empirical correlations development for heat transfer and friction factor of a solar rectangular air passage with spherical-shaped turbulence promoters

Journal of Thermal Analysis and Calorimetry - A study was conducted to enhance the thermo-hydraulic performance of a rectangular solar air passage with integrated spherical-shaped turbulence...