In vitro estimation of fast and slow wave parameters of thin trabecular bone using space-alternating generalized expectation-maximization algorithm

In testing cancellous bone using ultrasound, two types of longitudinal Biot’s waves are observed in the received signal. These are known as fast and slow waves and their appearance depend on the alignment of bone trabeculae in the propagation path and the thickness of the specimen under test (SUT). They can be used as an effective tool for the diagnosis of osteoporosis because wave propagation behavior depends on the bone structure. However, the identification of these waves in the received signal can be difficult to achieve.In this study, ultrasonic wave propagation in a 4 mm thick bovine cancellous bone in the direction parallel to the trabecular alignment is considered. The observed Biot’s fast and slow longitudinal waves are superimposed; which makes it difficult to extract any information from the received signal. These two waves can be separated using the space alternating generalized expectation maximization (SAGE) algorithm. The latter has been used mainly in speech processing.In this new approach, parameters such as, arrival time, center frequency, bandwidth, amplitude, phase and velocity of each wave are estimated. The B-Scan images and its associated A-scans obtained through simulations using Biot’s finite-difference time-domain (FDTD) method are validated experimentally using a thin bone sample obtained from the femoral-head of a 30 months old bovine.     

Equilibrium and kinetics study of Gd(III) and U(VI) adsorption from aqueous solutions by modified Sorrel’s cement

Modified Sorrel’s cement was prepared by the addition of ferric chloride. The modified cement (MF5) was analyzed and characterized by different methods. Adsorption of Gd(III) and U(VI) ions in carbonate solution has been studied separately as a function of pH, contact time, adsorbent weight, carbonate concentration, concentration of Gd(III) and U(VI) and temperature. From equilibrium data obtained, the values of Δ H, Δ S and Δ G were found to equal −30.9 kJ ⋅ mol⁻¹, −85.4 J ⋅ mol⁻¹ ⋅,K⁻¹, and −5.4 KJ ⋅ mol⁻¹, respectively, for Gd(III) and 18.9 kJ ⋅ mol⁻¹, 67.8 J ⋅ mol⁻¹ K⁻¹ and −1.3 KJ ⋅ mol⁻¹, respectively, for U(VI). The equilibrium data obtained have been found to fit both Langmuir and Freundlich adsorption isotherms. The batch kinetic of Gd(III) and U(VI) on modified Sorrel’s cement (MF5) with the thermodynamic parameters from carbonate solution were studied to explain the mechanistic aspects of the adsorption process. Several kinetic models were used to test the experimental rate data and to examine the controlling mechanism of the adsorption process. Various parameters such as effective diffusion coefficient and activation energy of activation were evaluated. The adsorption of Gd(III) and U(VI) on the MF5 adsorbent follows first-order reversible kinetics. The forward and backward constants for adsorption, k ₁and k ₂ have been calculated at different temperatures between 10 and 60^∘C. Form kinetic study, the values of Δ H ^* and Δ S ^* were calculated for Gd(III) and U(VI) at 25^∘C. It is found that Δ H ^* equals −14.8 kJmol⁻¹ and 7.2 kJmol⁻¹ for Gd(III) and U(VI), respectively, while Δ S ^* were found equal −95.7 Jmol⁻¹K⁻¹ and −70.5 Jmol⁻¹K⁻¹ for Gd(III) and U(VI), respectively. The study showed that the pore diffusion is the rate limiting for Gd(III) and (VI).     

Parameter analysis of the structure of matrix pencils by homotopic deviation theory

Let A, E ∈ ℂ^{n ×n} be two given matrices, where rank E = r < n. Matrix E is written in the form E = UV^H where U, V ∈ ℂ^{n ×r} have rank r. 0 is an eigenvalue of E with algebraic (resp. geometric) multiplicity m (g = n – r ≤ m). We consider the pencil P_z = (A – zI) + tE, defined for t ∈ ℂ and depending on the complex parameter z ∈ ℂ. We analyze how its structure [8] evolves as the parameter z varies, by means of conceptual tools borrowed from Homotopic Deviation theory [1, 3]. As an example with z = 0, the structure of the pencil A + tE is determined by Homotopic Deviation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Copper–acetanilide complexes: synthesis,characterization, crystal structure,computational analysis and their application as heterogeneous catalysts for biodiesel synthesis from frying waste oils

Research on Chemical Intermediates - Novel copper complexes were prepared from acetanilide derivatives and deliberately characterized. The molar ratio obtained was 1:1 through neutral bi-dentate...     

Synthesis and characterization of multiwall carbon nanotubes/alumina nanohybrid-supported cobalt catalyst in Fischer-Tropsch synthesis

Multiwall carbon nanotubes (MWNTs) and alumina are combined to give a new type of nanohybrid for Fisher-Tropsch synthesis (FTS) catalyst support. Alumina nano-particles (10 wt%) were introduced directly on functionalized MWNTs by a modified sol-gel method. Microstructure observations show that alumina particles were homogeneously dispersed on the inside and outside of modified MWNTs surfaces. 15 wt% cobalt loading catalysts were prepared with this nanohybrid and γ-alumina as a reference, using a sol-gel technique and wet impregnation method respectively. These catalysts were characterized by TEM, XRD, N₂-adsorption, H₂ chemisorption and TPR. The deposition of cobalt nanoparticles synthesized by sol-gel technique on the MWNTs nanohybrid shift the reduction peaks to a low temperature, indicating higher reducibility for uniform cobalt particles. Nanohybrid also aided in high dispersion of metal clusters and high stability and performance of catalyst. The proposed MWNTs nanohybrid-supported cobalt catalysts showed the improved FTS rate (g_HC/(g_cat·min)), CO conversion (%), and water gas shift rate (WGS)(g_CO2/(g_cat·h)) of 0.012, 52, and 30E-3, respectively, as compared to those of 0.007, 25, and 18E-3, respectively, on the γ-alumina-supported cobalt catalysts with the same Co loading.     

On Nuclei and Duals of Semifields of Order q 4, q is a Power of 2

The aim of this article is to investigate the nuclei of a semifield A of order q ⁴, q is a power of 2, admitting a four-group E of automorphisms isomorphic to Z ₂ × Z ₂ acting freely on A and having GF(q ²) in its left nucleus. We also study the dual semifield A* of A and show that A and A* are isomorphic.     

Detection of pyridaben residue levels in hot pepper fruit and leaves by liquid chromatography–tandem mass spectrometry: effect of household processes

Following quick, easy, cheap, effective, rugged and safe (QuEChERS) and LC/MS/MS analysis, pyridaben residual levels were determined in unprocessed and processed hot pepper fruit and leaves. The linearities were satisfactory with determination coefficients (R²) in excess of 0.995 in processed and unprocessed pepper fruit and leaves. Recoveries at various concentrations were 79.9–105.1% with relative standard deviations ≤15%. The limits of quantitation of 0.003–0.012 mg/kg were very low compared with the maximum residue limits (2–5 mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. The effects of various household processes, including washing, blanching, frying and drying under different conditions (water volume, blanching time and temperature) on residual concentrations were evaluated. Both washing and blanching (in combination with high water volume and time factor) significantly reduced residue levels in hot pepper fruit and leaves compared with other processes. In sum, the developed method was satisfactory and could be used to accurately detect residues in unprocessed and processed pepper fruit and leaves. It is recommended that pepper fruit/leaves be blanched after washing before being consumed to protect consumers from the negative health effects of detected pesticide residues. Copyright © 2014 John Wiley & Sons, Ltd.     

Discrete and generalized phase space techniques in critical quantum spin chains

We apply the Wigner function formalism from quantum optics via two approaches, Wootters' discrete Wigner function and the generalized Wigner function, to detect quantum phase transitions in critical spin-$\frac{1}{2}$ systems. We develop a general formula relating the phase space techniques and the thermodynamical quantities of spin models, which we apply to single, bipartite and multi-partite systems governed by the XY and the XXZ models. Our approach allows us to introduce a novel way to represent, detect, and distinguish first-, second- and infinite-order quantum phase transitions. Furthermore, we show that the factorization phenomenon of the XY model is only directly detectable by quantities based on the square root of the bipartite reduced density matrix. We establish that phase space techniques provide a simple, experimentally promising tool in the study of many-body systems and we discuss their relation with measures of quantum correlations and quantum coherence.     

Efficient and facile one pot carboxylation of multiwalled carbon nanotubes by using oxidation with ozone under mild conditions

In this study, oxidation of carbon nanotubes with ozone in the presence of hydrogen peroxide was investigated. The reaction was performed under clean and mild conditions and oxidized products with high concentration of oxygenated groups were yielded. The reaction products were characterized with attenuated total reflectance (ATR), Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffractometry (XRD), back titration, X-ray photoelectron spectroscopy (XPS) and the dispersion behavior of the oxidized multiwalled carbon nanotubes (MWCNTs) was also studied. The results confirmed the presence of high concentrations of oxidative groups on the carbon nanotubes (CNTs) treated by the method of the present work.     

Preparation of piperazine-grafted amine-functionalized UiO-66 metal organic framework and its application for CO<Subscript>2</Subscript> over CH<Subscript>4</Subscript> separation

UiO-66 amine functionalized was synthesized by solvothermal method. Post-synthetic modification of UiO-66-NH₂ with piperazine, a known promoter to enhance the chemisorption rate of CO₂ uptake, was carried out and analyzed to understand its crystalline structure, morphology and porous structure. Results show that piperazine is an effective agent for enhancing the capacity of absorption of CO₂. This porous product exhibits an improved CO₂ uptake at pressures up to 3000 kPa via physisorption and chemisorption mechanisms. The CH₄ adsorption and desorption isotherms on UiO-66, UiO-66-NH₂ and pip-UiO-66-NH₂ at temperature of 298.15 K and pressures ranging from 0 to 5000 kPa were carried out. IAS theory for a mixture of 0.05 bar CO₂, 0.85 bar CH₄ and 0.1 bar other gas revealed a selectivity factor of 19.09 for CO₂/CH₄ from pip-UiO-66-NH₂. Results show that these materials are effective adsorbents for CO₂ and CH₄ uptakes.