Microwave Assisted Synthesis of Chitosan Nanoparticles

Chitosan nanoparticles (CHN) were prepared based on ionotropic gelation between low moleculer weight chitosan and sodium tripolyphosphate (TPP) under microwave irradiation. Particle size, zeta potential, and FT-IR techniques were used for characterization of CHN. The influence of reaction time on the nanoparticle size distribution was investigated, and the results showed that the microwave irradiation method evidently decreases the reaction times and particle size over the conventional method. It was determined by the results of the zeta potential measurements that synthesized CHN under microwave irradiation clearly exhibits more homogeneous and stable dispersion.     

18FDG conjugated magnetic nanoparticle probes: synthesis and in vitro investigations on MCF-7 breast cancer cells

¹⁸FDG conjugated magnetic iron oxide nanoparticles (MNPs) were synthesized as PET-MR hybrid imaging agent. Synthesized and characterized NPs were then applied to MCF-7 human breast cancer cells. ¹⁸FDG conjugated MNPs exhibited the cell incorporation ratio up to 30 %. As well as the characterization studies, apoptotic effects were observed depending on the cellular incorporations by the time. In conclusion, synthesized structures could have a potential as hybrid imaging agent in PET-MR imaging systems besides apoptotic effect on cancer cells.     

PHOTOREDUCTION OF THIONINE BY WATER

Abstract —The photoreduction of thionine by water has been studied, using a technique applied in earlier work on photoreduction of methylene blue. It is found for thionine as for methylene blue, that a long-lived excited intermediate is formed, and that two such intermediates react to produce a single reduced molecule, thus providing adequate energy for the reaction. The mechanism proposed for methylene blue photoreduction is shown to be applicable to thionine photoreduction as well, indicating the unimportance of the amine methyl groups. Although in previous work it was suggested that H₂O was the reducing agent, none of them, however, could determine the H₂O₂ formed. The formation of H₂O₂ is confirmed in this work, and the kinetics of its formation are shown to be in accordance with the mechanism.     

The Crystal and Molecular Structure of Two Drug Compounds: Tazettine and Corydaldine

The title compounds Tazettine (C₁₈H₂₁NO₅) and Corydaldine (3,4-dihydro-6,7-dimethoxy-1(2H)-isoquinolinone, C₁₁H₁₃NO₃) have been isolated from the bulbs of Pancratium maritimum L. (Amaryllidaceae) and Corydalis solida subspecies brachyloba, respectively. The X-ray structures were solvcd for Tazettine (I) and Corydaldine (II) (λ MoK_α, R = 0.0499 and 0.0418, respectively). Crystals of (I) are orthorhombic, a = 7.115(1), b =13.377(1), c = 16.878(1) Å, Z = 4, D_cale = 1.370 g. cm⁻³, space group P2₁2₁2₁. Crystals of (II) are monoclinic, a =10.641(1), b = 6.636(1), c = 14.938(1) Å, β = 90.31(1)°, Z = 4, D_calc = 1.305 g. cm⁻³, space group P2₁/a.     

Expansion of the boundaries of the solutions of the linear Volterra integral equations with convolution kernel

We solve a certain differential equation and system of integral equations. As applications, we characterize holomorphic symbols of commuting Toeplitz operators on the pluriharmonic Bergman space. In addition, pluriharmonic symbols of normal Toeplitz operators are characterized. Also, zero semi-commutators for certain classes of Toeplitz operators are characterized.This research is partially supported by KOSEF(98-0701-03-01-5).     

Optimal assignment of broadcasting frequencies

As a result of major developments in communication technology, the electromagnetic spectrum is now a ‘significant’ but ‘scarce’ resource. The broadcasting frequencies/channels/ bands must be assigned to applicants in an optimal manner so that larger numbers of applicants can be accommodated. This problem is constructed as a 0–1 programming problem. Numerical examples are also presented.     

Dynamic hysteresis loops of the spin-2 bilayer Ising model

Based on the mean-field theory and Glauber-type stochastic dynamics, the dynamic hysteresis loops (DHLs) of the spin-2 Ising model are studied on the bilayer square lattice. The DHLs are given for different values of temperature, crystal-field, exchange interaction and oscillating field frequency. It is found that the physical parameters have a strong effect on the shape and number of the DHLs. The results are compared with some theoretical and experimental works and found in a qualitatively good agreement.     

EFFECT OF WATER ON PHOTOCHEMICAL REDUCTION OF CONCENTRATED THIONINE SOLUTION BY VISIBLE LIGHT

Abstract— The photochemical reactions in concentrated thionine solution have been studied using continuous illumination. Thionine solution is photoreduced to leucothionine in an oxygen-free acidic medium. Electrochemical measurements of the photoreduction of thionine are reported. A possible reaction pathway for the energy transfer is proposed. It is found that polymeric forms of thionine and leucothionine are not involved in photoreduction. It is proposed that a complex must be formed prior to photochemical reduction. This complex species, having a lifetime of several seconds, is reduced to leucothionine, water being the reducing agent. Following this reduction, H₂O₂ is formed and the production of H₂O₂ is detected by differential pulse polarography.     

Dynamic phase transition in the kinetic Blume--Emery--Griffiths model: Phase diagrams in the temperature and interaction parameters planes

As a continuation of our previously published work, the dynamic phase transitions are studied further, within a mean-field approach, in the kinetic Blume--Emery--Griffiths model in the presence of a time varying (sinusoidal) magnetic field by using the Glauber-type stochastic dynamics. The dynamic phase transitions are obtained and the phase diagrams are constructed in two different planes, namely in the reduced temperature (T) and biquadratic interaction (k) plane and found eight fundamental types of phase diagrams for various values of reduced crystal-field interaction (d) and magnetic field amplitude (h), and in the (T,?d) plane and obtained six distinct topologies for different values of k and h. Phase diagrams exhibit one or two dynamic tricritical points and a dynamic double critical end point, dynamic triple and quadruple points, and besides disordered and ordered phases, three coexistence phase regions exist in which occurring of these strongly depend on the values of d, k and h.     

Multiplication operators on Lorentz-Karamata-Bochner spaces

In this small note, we will characterize the boundedness, compactness and closedness of the range of the multiplication operators on Lorentz-Karamata-Bochner spaces L _p,q;b (Ω,X) for p, q ∈ (0,∞].