Caesium carbonate supported on hydroxyapatite‐encapsulated Ni0.5Zn0.5Fe2O4 nanocrystallites as a novel magnetically basic catalyst for the one‐pot synthesis of pyrazolo[1,2‐b]phthalazine‐5,10‐diones

A novel nanomagnetic basic catalyst of caesium carbonate supported on hydroxyapatite‐coated Ni_0.5Zn_0.5Fe₂O₄ magnetic nanoparticles (Ni_0.5Zn_0.5Fe₂O₄@HAP‐Cs₂CO₃) was prepared. This new catalyst was fully characterized using Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, X‐ray diffraction and vibrating sample magnetometry techniques, and then the catalytic activity of this catalyst was investigated in the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives. Also, Ni_0.5Zn_0.5Fe₂O₄@HAP‐Cs₂CO₃ could be reused at least five times without significant loss of activity and could be recovered easily by applying an external magnet. Thus, the developed nanomagnetic catalyst is potentially useful for the green and economic production of organic compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Physicochemical properties and bio-interfacial interactions of surface modified PDLLA-PAMAM linear dendritic block copolymers

Here, we demonstrate the applicability of self-assembling linear-dendritic block copolymers (LDBCs) and their nanoaggregates possessing varied surfaces as therapeutic nanocarriers. These LDBCs are comprised of a hydrophobic, linear polyester chemically coupled to a hydrophilic dendron polyamidoamine (PAMAM)—the latter of which acts as the surface of the self-assembled nanoaggregate in aqueous media. To better understand how surface charge density affects the overall operability of these nanomaterials, we modified the nanoaggregate surface to yield cationic (NH₃⁺), neutral (OH), and anionic (COO⁻) surfaces. The effect of these modifications on the physicochemical properties (i.e., size, morphology, and surface charge density), colloidal stability, and cellular uptake mechanism of the polymeric nanocarrier were investigated. This comparative study demonstrates the viability of nanoaggregates formed from PDLLA-PAMAM LDBCs to serve as nanocarriers for applications in drug delivery.     

The stable forking conjecture and generic structures

 We prove that for any simple theory which is constructed via Fr?issé-Hrushovski method, if the forking independence is the same as the d-independence then the stable forking property holds. Received: 22 January 2001 / Published online: 19 December 2002 This article is part of the author's D-Phil thesis, written at the University of Oxford and supported by the Ministry of Higher Education of Iran. The author would like to thank the Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran, Iran, for its financial support whilst working on this article. Mathematics Subject Classification (2000): 03C45 Key words or phrases: Generic structures – Fr?issé-Hrushovski method – Predimension – Simple theories – Stable theories – Stable forking conjecture     

On the Numerical Range of Operator Polynomials

An upper bound for the number of components of the numerical range of matrix polynomials is established. We also establish a necessary condition and a sufficient condition for the connectedness of the numerical range of a quadratic selfadjoint matrix polynomial. The boundary of the numerical range of linear matrix polynomials is also considered.     

The effect of substituents on the extraction behavior of hydroxamic acids

The extraction behavior of several alkyl-substituted hydroxamic acids in chloroform solution with several metal ions is described. Among the N-phenylacylhydroxamic acids used, those with o-alkyl substituents on either the phenyl or acyl ring generally do not extract metals, apparently because of steric problems at the O=CNO^? chelation site. An improved synthesis of substituted hydroxamic acids is reported.     

Factors controlling the efficiencies of photoinduced electron-transfer reactions

The overall efficiencies of photoinduced electron transfer reactions in polar solvents are usually determined by the efficiency with which separated radical ions are formed from the initially formed geminate radical-ion pairs. These separation efficiencies are determined by the competition between retum electron transfer and separation within the geminate pairs. A method is described for determining whether variations in the quantum yields for formation of separated radical ions are due to changes in the reorganization parameters for the return electron transfer reactions, or to other factors. The use of the method is illustrated in studies of the effects of varying steric bulk and molecular size of the donors, and also in studies of the effect of using a charged sensitizer.     

A new thermostable peroxidase from garlic Allium sativum

Analysis of peroxidase activity by native polyacrylamide gel electrophoresis (PAGE) from a garlic bulb (Allium sativum L) extract showed two major activities (designated POX1 and POX2). The POX2 isoenzyme was purified to homogeneity by ammonium sulfate precipitation, gel filtration, and cation-exchange chromatography. The purified enzyme was found to be monomeric with a molecular mass of 36.5 kDa, as determined by sodium dodecyl sulfate-PAGE. The optimum temperature ranged from 25 to 40 degrees C and optimum pH was about 5.0. The apparent Km values for guaiacol and H2O2 were 9.5 and 2 mM, respectively. POX2 appeared highly stable since 50% of its activity was conserved at 50 degrees C for 5 h. Moreover POX2 was stable over a pH range of 3.5-11.0. Immobilization of POX2 was achieved by covalent binding of the enzyme to an epoxy-Sepharose matrix. The immobilized enzyme showed great stability toward heat and storage when compared with soluble enzyme. These properties permit the use of this enzyme as a biosensor to detect H2O2 in some food components such as milk or its derivatives.     

Structural characterization of single-walled carbon nanotube bundles by experiment and molecular simulation

A procedure, combining molecular simulation, Raman spectroscopy, and standard nitrogen adsorption, is developed for structural characterization of single-walled carbon nanotube (SWNT) samples. Grand canonical Monte Carlo simulations of nitrogen adsorption are performed on the external and internal adsorption sites of homogeneous arrays of SWNTs of diameters previously determined by Raman spectroscopy of the sample. The results show the importance of the peripheral grooves of a nanotube bundle at low relative pressure and the insensitivity of nanotube diameter toward adsorption on the external surface of the bundle at higher pressures. Simulations also reveal that samples containing thin nanotubes have less internal adsorption capacity that saturates at lower pressure than those comprising large diameter nanotubes. The fraction of open-ended nanotubes in a sample can be estimated by scaling the simulated internal adsorption inside nanotubes to obtain a near perfect fit between simulated and experimental isotherms. This procedure allows extrapolation of adsorption properties to conditions in which all nanotubes in the sample are open-ended.     

Electrode Kinetics and Ternary Complex Formation of Cd2+‐Antibiotics‐Vitamin‐B5 System. A Polarographic Study

Cd²⁺ complexes with antibiotics viz. neomycin, chlortetracycline, oxytetracycline, tetracycline, penicillin‐V and penicillin‐G as primary ligands and vitamin‐B₅ as secondary ligand have been reported at pH = 7.30 ± 0.01 and μ = 1.0 M KNO₃ at 298 K by polarographic technique.¹ Cd²⁺ formed 1:1:1, 1:1:2, and 1:2:1 complexes with a stability constants trend of neomycin < chlortetracycline < oxytetracycline < tetracycline < penicillin‐V < penicillin‐G can be explained on the basis of the nature of ligands, bonding, and steric hindrance of these drugs. The nature of electrode processes were reversible and diffusion controlled. The values of stability constants showed that these drugs can be used to reduce the toxicity of Cd.