Determination of Ethopabate Residues in Chicken Muscles, Liver, and Eggs after Aqueous SDS Extraction by Micellar Liquid Chromatography with Fluorescence Detection with Application to Baby Food

A simple and sensitive liquid chromatographic method was optimized and validated for the analysis of ethopabate residues in chicken muscles, liver, and eggs. Aqueous sodium dodecyl sulfate (SDS) solution was used for extraction. Analytical separation was performed in less than 8 min using a C18 column (150?×?4.6 mm internal diameter, 5 μm particle size) with fluorescence detection at 271/364 nm. A micellar solution composed of 0.1 M SDS, 10 % 1-propanol, and 0.3 % triethylamine in 0.02 M phosphoric acid adjusted to pH?4 was used as the mobile phase. The method was fully validated in accordance with International Conference on Harmonization guidelines. The micellar method was successfully applied to quantitatively determine ethopabate residues in spiked chicken muscles, liver, and eggs. It was also extended to the determination of ethopabate residues in chicken-based baby food. The recoveries obtained were in the 93.81–115.67 % range. The limit of detection was found to be 1.6 ng/g. High extraction efficiency for ethopabate was obtained without matrix interference and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step.     

Construction monitoring of urban tunnels and subway stations

Monitoring of tunnels and subway stations during construction using in-situ geotechnical instruments plays multiple essential technical roles. During early construction stages, it provides a factual basis for quantitative assessment of the proposed design and selected construction technology. If needed, such field measurements also can be used to guide modifications or refinement of the construction procedures, particularly at critical portions of the underground project. On the other hand, systematic instrumentation measurements taken at reasonably spaced control sections along the proposed alignment of a project can be utilized to document the overall performance. Such valuable records also can be used in a database for the design of similar future tunnels and for subway development. From the point of view of applied research, field measurements gathered during construction monitoring provide badly needed records for reviewing and improving the existing design procedures and validating new analytical tools, as well as for formulating effective directions of future research needs to match the mounting development of underground space. This paper outlines the basic requirements of successful construction monitoring program for urban underground projects, based on 15 years of experience in the design and implementation of more than 10 instrumentation test sections, mainly for tunnels and subway stations in Egypt and Canada. Some details of the most reliable in-situ instruments are also given. Finally, examples of different layouts of the monitoring programs implemented at different underground projects are presented, with some typical results.     

Higher-order horizontally-curved beam finite element including warping for steel bridges

The flexural stiffness for a horizontally curved beam element is developed for nodal parameters w_i, (?w/?s)_i, β_i, (?β/?s)_i, (?²β/?s²)_i, (?³β/?s³)_i by assuming a cubic displacement function for vertical deflection w, and a seventh order polynomical function for the angle of twist β, along the length of the curved beam. The element gives good accuracy with even coarse mesh for the analysis of horizontally-curved steel beam with open thin-walled bisymmetrical cross-section. Warping restraint is considered in the derivation of the stiffness matrix, which has considerable influence on the behavior and design of steel bridges curved in-plan. The results obtained from such a new element are compared with those given by a lower order finite element, developed previously by the first author, and with theoretical solutions for the particular problem.     

Formulation and corneal permeation of ketorolac tromethamine-loaded chitosan nanoparticles

Abstract

The aim of this work was to formulate chitosan (CS)-based nanoparticles (NPs) loaded with ketorolac tromethamine (KT) intended for topical ocular delivery. NPs were prepared using ionic gelation method incorporating tri-polyphosphate (TPP) as cross-linker. Following the preparation, the composition of the system was optimized in terms of their particle size, zeta potential, entrapment efficiency (EE) and morphology, as well as performing structural characterization studies using Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The data suggested that the size of the NPs was affected by CS/TPP ratio where the diameter of the NPs ranged from 108.0?±?2.4?nm to 257.2?±?18.6?nm. A correlation between drug EE and the corresponding drug concentration added to the formulation was observed, where the EE of the NPs increased with increasing drug concentration, for up to 10?mg/mL. FT-IR and DSC revealed that KT was dispersed within the NPs where the phosphate groups of TPP were associated with the ammonium groups of CS. The in vitro release profile of KT from CS NPs showed significant differences (p?<?0.05) compared to KT solution. Furthermore, mucoadhesion studies revealed adhesive properties of the formulated NPs. The KT-loaded NPs were found to be stable when stored at different storage conditions for a period of 3 months. The ex vivo corneal permeation studies performed on excised porcine eye balls confirmed the ability of NPs in retaining the drug on the eye surface for a relatively longer time. These results demonstrate the potential of CS-based NPs for the ocular delivery of KT.     

Interaction of tunnel linings and soft ground

Although soil-lining interaction is highly dependent on the tunnelling technology used, most of the available design methods for tunnel linings fail to take into consideration this important factor. During tunnel excavation, the in-situ stresses are significantly altered, depending on the tunnelling technique as well as the configuration of the tunnel and the characteristics of the soil deposits. The reduced radial stresses are the starting point of the soil-lining interaction at lining activation. This paper presents a method of lining design that considers the details of the excavation procedure and lining installation. Interaction between the tunnel lining and the ground is analysed in two stages—excavation and interaction. The excavation stage is responsible for determining the pre-lining soil deformations and the reduced in-situ stresses. The interaction stage models the soil-lining system together. Soil continuum, tunnel lining, and the interface between them are idealized in the whole system using nonlinear finite-element techniques. The deformations of the soil-lining system, as well as the lining internal forces, and equilibrium soil pressures are determined. Finally, results of the proposed analytical method as well as commonly used procedures are compared with field measurements compiled during the construction of two tunnels in which a precast segmental lining and rib and lagging lining were used.     

Heat and Mass Transfer at the Wall of a Square Mechanically Stirred Gas-Liquid-Solid Catalytic Reactor

Wall mass and heat transfer rates in a square gas-sparged, mechanically stirred reactor were measured by the electrochemical technique under the effect of various geometrical and hydrodynamic variables. For the 45° impeller, the mass transfer data fit the equation Sh = 0.7Sc^0.33Re^0.2Re_g^0.5 with an average deviation of ±6.9 %. For the 90° impeller, the data fit the equation Sh = 0.95Sc^0.33Re^0.14Re_g^0.53 with an average deviation of ±7.5 %. Gas sparging enhanced the wall mass transfer rates by factors of up to 2.61 and 3 for the 90° and 45° impellers, respectively, with a significant decrease in the total power consumption. The contribution of the present results to the operation of multiphase mechanically agitated vessels in different aspects is outlined.     

On the use of silicon as thermal neutron filter

A simple formula is given which allows to calculate the contribution of the total neutron cross-section including the Bragg scattering from different (hkl) planes to the neutron transmission through a solid crystalline silicon. The formula takes into account the silicon form of poly or mono crystals and its parameters. A computer program DSIC was developed to provide the required calculations. The calculated values of the total neutron cross-section of perfect silicon crystal at room and liquid nitrogen temperatures were compared with the experimental ones. The obtained agreement shows that the simple formula fits the experimental data with sufficient accuracy. A good agreement was also obtained between the calculated and measured values of polycrystalline silicon in the energy range from 5 eV to 500 μeV. The feasibility study on using a poly-crystalline silicon as a cold neutron filter and mono-crystalline as a thermal neutron one is given. The optimum crystal thickness, mosaic spread, temperature and cutting plane for efficiently transmitting the thermal reactor neutrons, while rejecting both fast neutrons and gamma rays accompanying the thermal ones for the mono crystalline silicon are also given.