Isotopic dilution analysis of zinc in some tissue samples of urogenital systems of rats using 65Zn

Zinc plays an important role in prostate functions. For this reason, in this study some rats have been nourished with foods containing different zinc levels and some tissue samples removed at different intervals of time from their prostate, testis, and seminal vesicle. The zinc contents of these samples have been determined using the isotopic dilution analysis technique applied with ⁶⁵Zn. In this way, the zinc contents of tissues varying between 0.02–4.50 μg Zn/g wet tissue could be determined with good precision. As a result, the zinc content of the prostate was found to be considerably high with respect to the zinc contents of the testis and the seminal vesicle. It is also interesting to note that a high zinc level in foods results in the accumulation of zinc in the prostate rather than in the testis and the seminal vesicle. The zinc content of the seminal vesicle decreases with a function of time passed from the beginning of the diet which contrasts with the case of prostate. It is also very remarkable that when the level of zinc in the body is low, the content of zinc in the testis is considerably higher.     

Absorption spectra of human skin in vivo in the ultraviolet wavelength range measured by optoacoustics

Knowledge of the optical properties of human skin in the ultraviolet range is fundamental for photobiologic research. However, optical properties of human skin in the ultraviolet spectral range have so far mainly been measured ex vivo . We have determined the absorption spectra of human skin in vivo in the wavelength range from 290 to 341 nm in 3 nm steps using laser optoacoustics. In this technique, optical properties are derived from the pressure profile generated by absorbed light energy in the sample. In a study on 20 subjects belonging to phototypes I–IV, we studied the optical properties at the volar and dorsal aspect of the forearm as well as on the thenar. Analysis of the measured absorption spectra shows that comparable skin areas—like different sides of the forearm—have qualitatively similar optical characteristics. Still, the optical properties may vary substantially within the same area, probably due to the skin structure and inhomogeneities. Comparison of the spectra from different skin sites indicates that the spectral characteristics of the stratum corneum and its chromophores play an important role for the optical properties of human skin in vivo in the ultraviolet B range.     

Ti6Al4V foams having nanotubular surfaces for orthopaedic applications

Despite the widespread use of Ti6Al4V in orthopaedics, the bioinert nature of this alloy limits its biological fixation with the bone tissue. To enhance its bone fixation, two different types of Ti6Al4V foams were fabricated, and their surfaces were modified zto possess nanofeatures. To prepare the foams, spherical- or irregular-shaped Ti6Al4V particles were used to form the backbones of the foams, while magnesium or carbamide powders were used as space holder agents. Once Ti6Al4V foams were fabricated, oxide-based nanotubular arrays having 40 nm diameter were formed on the interconnected pore surfaces via anodization. Results showed successful growth of nanotubular oxide arrays independent of the pore surface morphology, chemistry, and porosity content. Nanotubular surfaces induced formation of calcium phosphate minerals independent of the Ti6Al4V particle type and the space holder agent. Thus, anodized nanotubular Ti6Al4V foams could potentially induce enhanced integration of Ti6Al4V-based porous implants with the bone tissue.     

Analytical approach for the fractional differential equations by using the extended tanh method

In this study, we consider analytical solutions of space–time fractional derivative foam drainage equation, the nonlinear Korteweg–de Vries equation with time and space-fractional derivatives and time-fractional reaction–diffusion equation by using the extended tanh method. The fractional derivatives are defined in the modified Riemann–Liouville context. As a result, various exact analytical solutions consisting of trigonometric function solutions, kink-shaped soliton solutions and new exact solitary wave solutions are obtained.     

Computation of thermal fracture parameters for orthotropic functionally graded materials using Jk-integral

This article introduces a computational method based on the J_k-integral for mixed-mode fracture analysis of orthotropic functionally graded materials (FGMs) that are subjected to thermal stresses. The generalized definition of the J_k-integral is recast into a domain independent form composed of line and area integrals by utilizing the constitutive relations of plane orthotropic thermoelasticity. Implementation of the domain independent J_k-integral is realized through a numerical procedure developed by means of the finite element method. The outlined computational approach enables the evaluation of the modes I and II stress intensity factors, the energy release rate, and the T-stress. The developed technique is validated numerically by considering two different problems, the first of which is the problem of an embedded crack in an orthotropic FGM layer subjected to steady-state thermal stresses; and the second one is that of periodic cracks under transient thermal loading. Comparisons of the mixed-mode stress intensity factors evaluated by the J_k-integral based method to those calculated through the displacement correlation technique (DCT) and to those available in the literature point out that, the proposed form of the J_k-integral possesses the required domain independence and leads to numerical results of high accuracy. Further results are presented to illustrate the influences of the geometric and material constants on the thermal fracture parameters.     

Shallow trapping center parameters in as‐grown AgIn5S8 crystals determined by thermally stimulated current measurements

Thermally stimulated current measurements were carried out on as‐grown AgIn₅S₈ single crystals. The investigations were performed in temperatures ranging from 10 to 70 K with heating rate of 0.2 Ks^–1. The analysis of the data revealed the electron trap level located at 5 meV. The activation energies of the traps have been determined using various methods of analysis, and they agree with each other. The calculation for these traps yielded 2.2 × 10^–25 cm² for capture cross section and 6.1 × 10¹² cm^–3 for the concentration. It was concluded that in this center retrapping was negligible, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Enhancement of dispersion stability of inorganic additives via poly(sodium-4-styrenesulfonate) treatment geared to hydrogel applications

This study reports the preparation of poly(sodium-4-styrene sulfonate) (PSS) treated bentonite and clinoptilolite to prevent the agglomeration and sedimentation of these inorganic fillers during the preparation of hydrogel. For this purpose PSS treated fillers were prepared by using various techniques (dip and dry, hydrothermal, one-step ball milling and ultrasonication methods). The most suitable technique for preparing these PSS treated inorganic fillers (abbreviated as BP-dip and CP-dip) was the dip and dry method. BP-dip and CP-dip based polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) composite hydrogels were prepared using the freeze/thawing method after the addition of one of BP-dip and CP-dip inorganic fillers in various amounts. The swelling properties, stability behaviors and Rhodamine B (RhB) adsorption of the composite hydrogels were studied. It was found that the swelling degrees of CP-dip and BP-dip based composite hydrogels with 25 mg of filler were higher than that of all other samples. The kinetic mechanism of RhB adsorption process and the related characteristic kinetic parameters were investigated by Pseudo kinetic models. The adsorption kinetics results for RhB adsorption were found best fitted with pseudo-second-order kinetics model. The maximum RhB adsorption capacity was determined to be for PVA/PVP-CP-dip25, which was 3.3 times higher than that of the unfilled PVA/PVP hydrogel.     

Quantitative Approximation by Fractional Generalized Discrete Singular Operators

Results in Mathematics - In this article, we study the fractional generalized smooth discrete singular operators on the real line, the univariate and non-univariate cases, regarding their...     

RAFT made methacrylate copolymers for reversible pH‐responsive nanoparticles

In this study, we designed and investigated pH‐responsive nanoparticles based on different ratios of monomers with primary, secondary or tertiary amino groups. For this purpose, copolymers of methyl methacrylate (MMA) with different compositions of amino methacrylates (2‐(dimethylamino)ethyl methacrylate (DMAEMA), 2‐(tert‐butylamino)ethyl methacrylate (tBAEMA) and 2‐aminoethyl methacrylate hydrochloride (AEMA·HCI)) were synthesized using the reversible addition‐fragmentation chain transfer (RAFT) polymerization process. The controlled nature of the radical polymerization was demonstrated by kinetic studies. All copolymers show low dispersities (?_M < 1.2) with amino contents between 9 and 21 mol %. For the nanoparticle formation, nanoprecipitation with subsequent solvent evaporation was used. All suspensions were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Different initial conditions of the formulations resulted in differently sized nanoparticles that have monomodal size distributions, relatively narrow polydispersity index (PDI) values and positive zeta potential values. The pH‐stability test results demonstrated that, depending on the structure and amount of the amino content, the obtained nanoparticles reveal a reversible pH‐response, such as dissolution at acidic pH values. The ability of the nanoparticles to encapsulate guest molecules was confirmed by pyrene fluorescence studies. The cytotoxicity assay results showed that the nanoparticles did not have any significant cytotoxic effect. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2711–2721