Photochemistry of desonide, a non-fluorinated steroidal anti-inflammatory drug

The photochemistry of anti-inflammatory drug desonide (De, 1) was studied in aerobic as well as in anaerobic condition with different irradiation wavelengths (254, 310 nm) in acetonitrile and 2-propanol. All photoproducts obtained were isolated and characterized on the basis of IR, (1)H-, (13)C-NMR spectroscopy and elemental analysis study. The products were: 11beta,21-dihydroxy-16alpha,17alpha-(1-methylethylidenedioxy)-1,5-cyclopregn-3-ene-2,20-dione 2 (254 nm), 11beta-hydroxy-16alpha,17alpha-(1-methylethylidenedioxy)androsta-1,4-diene-3-one 3 (310 nm/2-propanol), 17beta-hydroperoxy-11beta-hydroxy-16alpha,17alpha-(1-methylethylidenedioxy)androsta-1,4-diene-3-one 4 (310 nm/O(2)/2-propanol). Cyclohexadienone moiety in ring A and keto group at C(17) were found to be deeply modified by UV light therefore, loss of biological activity both during storage and in vivo can not be ruled out.     

Use of ionic liquid based chitosan as sorbent for preconcentration of fluoroquinolones in milk,egg, fish,bovine, and chicken meat samples by solid phase extraction prior to HPLC determination

The possibility of using ionic liquid based chitosan sorbent for the separation and preconcentration of fluoroquinolone antibiotics (marbofloxacin, enoxacin, ofloxacin, ciprofloxacin, and enrofloxacin) has been studied. For this reason, different ionic liquids were prepared and coated on the chitosan sorbent. The conditions of the preconcentration of fluoroquinolones on a microcolumn have been optimized and the extraction efficiencies of the prepared sorbents have been compared. The compounds were eluted with 5 mL of 20% NH₃ (v/v, MeOH) solution and determined by HPLC with diode array and fluorescence detector. The limits of detection were found as 4.23 µ g L^?1 for marbofloxacin, and 1.09 µg L^?1 for enoxacin; 3.23 × 10^?3 µg L^?1 for ofloxacin; 8.39 × 10^?3 µg L^?1 for ciprofloxacin; and 19.50 × 10^?3 µg L^?1 for enrofloxacin. The developed method was applied for the analysis of fluoroquinolone in milk, egg, fish, bovine, and chicken samples and the recoveries were obtained in the range 70–100%.     

Synthesis,characterization and catalytic properties of cationic N-heterocyclic carbene silver complexes

Three new dibenzimidazolium salts bridged by 2-methylenepropane-1,3-diyl group were synthesized. Their dinuclear N-heterocyclic carbene Ag(I) complexes were prepared by the reactions of these salts with Ag₂O. The structures of the synthesized compounds were defined by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, and LC-MSMS (for complexes) techniques. Stability of the silver complexes was confirmed by ¹H NMR spectroscopy. Catalytic activities of Ag(I) compounds were tested for three-component coupling reaction of some aldehydes, amines, and phenylacetylene.     

Thermal entanglement in the mixed three-spin XXZ Heisenberg model on a triangular cell

We numerically investigate the thermal entanglements of spins （1/2, 1） and spins （1/2, 1/2） in the three-mixed （1/2, 1, 1/2） anisotropic Heisenberg XXZ spin system on a simple triangular cell under an inhomogeneous magnetic field. We show that the external magnetic field induces strong plateau formation in the pairwise thermal entanglement for fixed parame-ters of the Hamiltonian in the cases of ferromagnetic and antiferromagnetic interactions. We also .observe an unexpected critical point at finite temperature in the thermal entanglement of spins （1/2, 1） for the antiferromagnetic case, while the entanglement of spins （1/2, 1） in the ferromagnetic case and the entanglement of spins （1/2, 1/2） in both ferromagnetic and antiferromagnetic cases almost decay exponentially to zero with increasing temperature. The critical point in the en-tanglement of spins （1/2, 1） in the antiferromagnetic case may be a signature of the quantum phase transition at finite temperature.     

Indium phosphide nanofibers prepared by electrospinning method: Synthesis and characterization

Nine sets of (3 × 3) InP nanofiber samples have been successfully prepared at three different voltages (20, 25, 30 kV) and at three separate heights (5, 7, 10 cm) by electrospinning with a constant precursor flow rate of 0.3 mLh⁻¹. The crystalline structure, thermal, morphologies and nanostructure, electrical, and optical properties of the samples are characterized by X‐ray powder diffractometer (XRD) and thermal gravity‐differential scanning calorimeter (TG‐DSC), scanning electron microscopy (SEM), by Four‐Point Probe Technique (FPPT,) and ultraviolet/visible spectrometry (UV/VIS), respectively. From these measurements, we have found the formation of stoichiometric nanostructured InP with zinc‐blende structure and having lattice parameter of a = 5.874 Å, weight loss of 64.59% and crystallization temperature of 500°C, average fiber diameter of 65.82 nm, the activation energies, E_a, of the samples, and band gap energy, E_g, of the nanofibers developed at constant applied voltage 30 kV. The band gap energies determined at different distances 5, 7, and 10 cm are found to be as 1.29, 1.37, and 1.30 eV, respectively.     

Improvement of piezoelectric transformer performances using SSHI and SSHI-max methods

The piezoelectric transformers reach densities of power more significant than their magnetic counterparts. However, one of the principal factors limiting the density of power is the acceptable maximum deformation by material constituting the transformer. The heating of the piezoelectric transformers is mainly of mechanical origin. This heating generates a degradation of the characteristics which in its turn generates an additional heating being able to lead to a phenomenon of thermal avalanche. In this work, two nonlinear methods [synchronized switch harvesting on inductor (SSHI) and SSHI-max] have been explored to improve the performance of the Rosen transformer basing on the tension generated by the secondary so as to increase the capacity of mechanic-electric conversion. The simulation results show that SSHI and SSHI-max techniques significantly increase the capacity of mechanic-electric conversion of inserts stuck on a vibrating structure and consequently, the power recovered in electric form. The comparative results of voltage gain, efficiency and the transmitted power of the transformer, before and after SSHI-max and SSHI control are given. These ones indicated that the two nonlinear techniques are promising as applications to improve the performances of the piezo-transformers.     

A technique for digital steganography using chaotic maps

Chaos has been applied extensively in secure communication over the last decade, but most of the chaotic security protocols defined, are cryptographically weak or slow to compute. Also, study of chaotic phenomena as application in security area is not discussed in detail. In this paper, we have intensely studied chaos, their influence in secure communications and proposed a steganography technique in spatial domain for digital images based upon chaotic maps. By applying chaos effectively in secure communication, the strength of the overall anticipated algorithm has been increased to a significant level. In addition, few security statistical analyses such as correlation, entropy, energy, contrast, homogeneity, peak signal to noise ratio, and mean square error have also been carried out and shown that it can survive against various differential attacks such as the known message attack, known cover attack, known stego attack, and stego only attack.     

Dye attached poly(hydroxyethyl methacrylate) cryogel for albumin depletion from human serum

Cibacron Blue F3GA was immobilized on poly(hydroxyethyl methacrylate) cryogel and it was used for selective and efficient depletion of albumin from human serum. The poly(hydroxyethyl methacrylate) was selected as the basic component because of its inertness, mechanical strength, chemical and biological stability, and biocompatibility. Cibacron Blue F3GA was covalently attached to the poly(hydroxyethyl methacrylate) cryogel to produce poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel affinity column. The poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel was characterized with respect to gelation yield, swelling degree, total volume of macropores, Fourier Transform Infrared spectroscopy, and scanning electron microscopy. It was found that the maximum amount of adsorption (343 mg/g of dry cryogel) obtained from experimental results is very close to the calculated Langmuir adsorption capacity (345 mg/g of dry cryogel). The maximum adsorption capacity for poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel column was obtained as 950 mg/g of dry cryogel for nondiluted serum. The adsorption capacity decreased with increasing dilution ratios while the depletion ratio of albumin remained as 77% in serum sample. Finally, the poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel was optimized for using in the fast protein liquid chromatography system for rapid removal of the high abundant proteins from the human serum.     

Self-assembly of doublets from flattened polymer colloids

Bottom-up fabrication methods are used to assemble strong yet flexible colloidal doublets. Part of a spherical particle is flattened, increasing the effective interaction area with another particle having a flat region. In the presence of a moderate ionic strength, the flat region on one particle will preferentially "bond" to a flat region on another particle in a deep (≥10 kT) secondary energy minimum. No external field is applied during the assembly process. Under the right conditions, the flat-flat bonding strength is ≥10× that of a sphere-sphere interaction. Not only can flat-flat bonds be quite strong, but they are expected to remain freely rotatable and flexible, with negligible energy barriers for rotation because particles reside in a deep secondary energy minimum with a ~20-30 nm layer of fluid between the ~1 μm radius particles. We present a controlled technique to flatten the particles at room temperature, the modeling of the interparticle forces for flattened spheres, and the experimental data for the self-assembly of flat-flat doublets.     

Purification of Papain Using Reactive Green 5 Attached Supermacroporous Monolithic Cryogel

Supermacroporous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] monolithic cryogel was prepared by radical cryocopolymerization of HEMA with N,N??-methylene bisacrylamide as crosslinker. Reactive Green 5 dye was immobilized to the cryogel with nucleophilic substitution reaction, and this dye attached cryogel column was used for affinity purification of papain from Carica papaya latex. Reactive Green 5-immobilized poly(HEMA) cryogel was characterized by swelling studies, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis. Maximum papain adsorption capacity was found to be 68.5?mg/g polymer while nonspecific papain adsorption onto plain cryogel was negligible (3.07?mg/g polymer). Papain from C. papaya was purified 42-fold in single step with dye attached cryogel, and purity of papain was shown by silver-stained sodium dodecyl sulfate?Cpolyacrylamide gel electrophoresis.