LC-ESI-MS/MS determination of paclitaxel on dried blood spots

A simple and rapid high‐performance liquid chromatography–tandem mass spectrometric assay for determination of paclitaxel on rat dried blood spots was developed and validated. The extracted sample was chromatographed without further treatment using a reverse‐phase Oyster ODS3, 4.6 × 50 mm, 3 µm column with mass spectrometry detection. The mobile phase comprised of acetonitrile–water, 60:40 v/v, with a flow rate of 0.4 mL/min was used. The calibration was linear over the range 0.2–20 ng/mL. The limits of detection and quantification were 0.08 and 0.2 ng/mL, respectively. The intra‐ and inter‐day precision (CV%) and accuracy (relative error %) were less than 10 and 12%, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

A nano-fibrillated mesoporous carbon as an effective support for palladium nanoparticles in the aerobic oxidation of alcohols "on pure water"

A novel nano-fibrillated mesoporous carbon (IFMC) was successfully prepared via carbonization of the ionic liquid 1-methyl-3-phenethyl-1H-imidazolium hydrogen sulfate (1) in the presence of SBA-15. The material was shown to be an efficient and unique support for the palladium nanoparticle (PdNP) catalyst Pd@IFMC (2) in aerobic oxidation of heterocyclic, benzylic, and heteroatom containing alcohols on pure water at temperatures as low as 40 °C for the first time and giving almost consistent activities and selectivities within more than six reaction runs. The catalyst has also been employed as an effective catalyst for the selective oxidation of aliphatic and allylic alcohols at 70-80 °C. The materials were characterized by X-ray photoelectron spectroscopy (XPS), N(2) adsorption-desorption analysis, transmission electron microscopy (TEM), and electron tomography (ET). Our compelling XPS and ET studies showed that higher activity of 2 compared to Pd@CMK-3 and Pd/C in the aerobic oxidation of alcohols on water might be due to the presence of nitrogen functionalities inside the carbon structure and also the fibrous nature of our materials. The presence of a nitrogen heteroatom in the carboneous framework might also be responsible for the relatively uniform and nearly atomic-scale distribution of PdNPs throughout the mesoporous structure and the inhibition of Pd agglomeration during the reaction, resulting in high durability, high stability, and recycling characteristics of 2. This effect was clearly confirmed by comparing the TEM images of the recovered 2 and Pd@CMK-3.     

Reliability verification for composite structures of annular cross section

The performance and reliability of tubular composite structures are considered. The suitability of concrete-filled plastic and steel tubes for building structures is discussed. The strength and structural safety of tubular composite members of annular cross section are analyzed, and the criteria of limit states for tubular composite members under concentric and eccentric axial compression are studied. The time-variant functions of efficiency of the members and their components are presented as random processes of variations in their compressive resistance and internal actions. The safety design of the members is based on the conceptions of their conventional resistance, sequences of safety margin, and transformed conditional probabilities.     

Comparative study of nanoscale surface structures of calcite microcrystals using FE-SEM, AFM, and TEM.

The bulk morphology and surface features that developed upon precipitation on micrometer-size calcite powders and millimeter-size cleavage fragments were imaged by three different microscopic techniques: field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) of Pt-C replicas, and atomic force microscopy (AFM). Each technique can resolve some nanoscale surface features, but they offer different ranges of magnification and dimensional resolutions. Because sample preparation and imaging is not constrained by crystal orientation, FE-SEM and TEM of Pt-C replicas are best suited to image the overall morphology of microcrystals. However, owing to the decoration effect of Pt-C on the crystal faces, TEM of Pt-C replicas is superior at resolving nanoscale surface structures, including the development of new faces and the different microtopography among nonequivalent faces in microcrystals, which cannot be revealed by FE-SEM. In conjunction with SEM, Pt-C replica provides the evidence that crystals grow in diverse and face-specific modes. The TEM imaging of Pt-C replicas has nanoscale resolution comparable to AFM. AFM yielded quantitative information (e.g., crystallographic orientation and height of steps) of microtopographic features. In contrast to Pt-C replicas and SEM providing three-dimensional images of the crystals, AFM can only image one individual cleavage or flat surface at a time.     

Consistent Behavior of Eulerian Monte Carlo fields at Low Reynolds Numbers

A slightly different version of the Eulerian Monte Carlo method (EMC) (Valiño, Flow Turbul. Combust. 60, 157–172, (1998)) is presented in this paper. The EMC method is an effective stochastic numerical approach to solve the Probability Density Function (PDF) of reacting species in turbulent flows. In contrast with the original formulation, the spurious Wiener term associated with the molecular diffusion is removed, by splitting the micro-mixing into mean gradient and fluctuating contributions. The evolution of the EMC fields representing the PDF in the proposed formulation is then consistent in the laminar limit: the EMC fields follow the same standard convection-diffusion equation, without any stochastic terms.     

Influence of surface topography and annealing temperature on the surface and volume of dissipation electrical energy and Spitzer–Fan model in Al doped ZnO films

The aim of this work is to investigate the optical constants of aluminum doped zinc oxide films annealed at different temperatures. With increasing temperature, due to decreasing unfilled inter-granular volume per unit thickness, the optical transmittance spectra of films were increased. The films have a normal dispersion in the spectral range 400?<?λ?<?500 nm and the anomalous dispersion in IR range. The lattice dielectric constants ε_L, the free charge carriers concentration, the plasma frequency, Spitzer–Fan model and the waste of electrical energy as heat of films can be analyzed using the refractive index n and the extinction coefficient k spectra. With increasing annealing temperature, the lattice dielectric constants ε_L of films decrease however the free charge carriers concentration of films increase. The free carrier electric susceptibility of films annealed at 600 °C has maximum value. The energy loss by the free charge carriers when traversing the bulk and surface of films annealed at 600 °C has a minimum value in the near fundamental absorption edge and it with increasing energy increases.     

Investigation of vacancy defects effects on the buckling behavior of SWCNTs via a structural mechanics approach

In this paper, the influence of various vacancy defects on the critical buckling loads and strains in carbon nanotubes under axial compression is investigated via a new structural model in ABAQUS software. The necessity of desirable conditions and expensive tests for experimental methods, in addition to the time expenditure required for atomic simulations, are the motivation for this work, which, in addition to yielding accurate results, avoids the obstacles of the previous methods. In fact, this model is a combination of other structural models designed to eliminate the deficiencies inherent in individual approaches. Because the present model is constructed in the CAE space of ABAQUS, there is no need to program for different loading and boundary conditions. A nonlinear connector is considered for modeling of stretching and torsional interactions, and a nonlinear spring is used for modeling of the angle variation interactions. A Morse potential is employed for stretching and bending potentials, and a periodic type of bond torsion is used for torsion interactions. The effect of different types of vacancy defects at various locations on the critical buckling loads and strains is studied for zigzag and armchair nanotubes with various aspect ratios (Length/Diameter). Comparison of our results with those of buckling of shells with cutouts indicates that vacancy defects in the carbon nanotubes can most likely be modeled as cutouts of the shells. Finally, results of the present structural model are compared with those from molecular dynamics (MD) simulation and show good agreement between our model and the MD model.     

Pre-oxidative catalytic treatment of toluidine blue with potassium permanganate in acidic solution

This article describes the potential of KMnO₄ for oxidation of the thiazine dye (Toluidine blue TB) in an acidic medium. The effect of different operational parameters like initial concentration of dye, potassium permanganate, pH, ionic strength, catalyst, acids and temperature were investigated spectrophotometrically at λ _max = 613 nm. The results showed a complete removal of the TB with mineralization of the dye solution. Smooth and complete decoloration was observed in the presence of monobasic acid (HCl) as compared to the H₂SO₄ where little color removal was observed. Pb was found to be an effective catalyst in oxidation for complete and fast decolorization with mineralization. No significant change at elevated temperatures showed that an intermediate complex degraded with slight change in the temperature. UV/visible spectrophotometry and GC mass analysis showed an intermediate activated complex demethylated sulophooxide of TB which later on degraded into smaller fragments.     

Two-point laser Doppler velocimetry measurements in a Mach 1.2 cold supersonic jet for statistical aeroacoustic source model

Single and multi-point laser Doppler velocimetry measurements performed in a cold Mach 1.2 jet flow are used to assess those properties of the aerodynamic field most relevant in the generation of turbulence mixing noise. Single point measurements yield mean velocity profiles, turbulence intensity profiles and power spectral densities of both the velocity and Reynolds stress fields at seven axial stations between the jet exit and the end of the potential core. The longitudinal components of the second-order and fourth-order two-point velocity correlation tensor are obtained from a series of multi-point LDV measurements, whence a cartography of integral space and time scales, convection velocities and acoustic compactness is effected. These results are used to examine differences between subsonic and supersonic jet aerodynamics in terms of their sound generating potential. Finally analytical expressions are proposed for the spatial and temporal parts of the longitudinal correlation coefficient function. These are scaled using the integral space and time scales of the velocity and Reynolds stress fields, and excellent agreement is found with experimentally determined functions.Nomenclature  c_o  Sound speed - D  Exit nozzle diameter - f, f  Spatial correlation function - g, g  Temporal correlation function - f_St  Frequency based Strouhal number - _i  2nd-order integral length scales in i-th direction -  4th-order integral length scales in i-th direction - M_c  Convective Mach number - M_j Jet exit Mach number - q Quantity q evaluated at location y into the flow -  Time average of the quantity q - r Radial distance from the jet exit - r_0.5  Radial location of the shear layer axis - r* Normalised radial coordinate - r_ij Second-order velocity correlation - r_ijkl Fourth-order velocity correlation - St Jet Strouhal number - U_c Convective velocity - U_e Subsonic coflow velocity - U_j Jet exit velocity - U_i Mean part of u_i - u_i Local velocity in i-th direction - u_ti Fluctuating part of u_i - x Distance from the exit nozzle - y Location test point - _i Variance of the velocity component u_i - _ij Variance of the velocity product u_iu_j -  Constant value - _ij Kronecker delta - _c Shear layer thickness - t_i Interarrival time between two ldv samples -  Separation distance in the moving pattern (components _i ) -  Polynomial function -  Separation distance in the fixed pattern (components _i ) -  Time delay -  2nd-order time scale in the fixed pattern -  2nd-order time scale in the moving pattern -  4th-order time scale in the fixed pattern -  4th-order time scale in the moving pattern -  Typical radian frequency where

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