Iron-oxide-modified nanosized diamond: preparation, characterization, and catalytic properties in methanol decomposition

Nanosized diamond (UDD), obtained by a detonation procedure, was modified with iron from the corresponding acetylacetonate precursor under various pretreatment conditions. Nitrogen physisorption, X-ray diffraction, temperature-programmed reduction, and FTIR and M?ssbauer spectroscopy were used for their characterization. The samples' catalytic behavior in methanol decomposition was also studied. The physicochemical and catalytic properties of the obtained materials (Fe/UDD) were compared with those of other iron-oxide-modified mesoporous supports with different nature and functionality (MCM-48 silica and CMK-1 carbon). The highest catalytic activity and stability was achieved with air-pretreated Fe/UDD.     

X-ray diffraction area mapping of preferred orientation and phase change in TiO2 thin films deposited by chemical vapor deposition

This paper reports on an investigation into the formation of TiO(2) thin films, whereby X-ray diffraction is used to map systematic changes in preferred orientation and phase observed throughout the films. The key to this strategy is the recording of X-ray diffraction patterns of specific and isolated areas of a substrate, ensuring this specificity by the use of a small X-ray sample illumination area (approximately 3-5 mm(2)). A map of the variation in film composition can then be built up by recording such diffraction patterns at regular intervals over the whole substrate. Two titania films will be presented, grown using atmospheric pressure chemical vapor deposition, at 450 and 600 degrees C, from TiCl(4) and ethyl-acetate precursors. The film grown at 450 degrees C showed a systematic change in preferred orientation, while the film grown at 600 degrees C was composed of a mixture of the rutile and anatase phases of TiO(2) with the ratio of these phases altering with position on the substrate. The results of physical property measurements and electron microscopy carried out on the films are also reported, conducted at locations identified by the X-ray diffraction mapping procedure as having different compositions, and hence different physical responses. We found that the photocatalytic activity and hydrophobicity were dependent on the rutile:anatase ratio at any given location on the film.     

Formal relations connecting different approaches to calculate relativistic effects on molecular magnetic properties

In the present work a set of formal relations connecting different approaches to calculate relativistic effects on magnetic molecular properties are proven. The linear response (LR) within the elimination of the small component (ESC), Breit Pauli, and minimal-coupling approaches are compared. To this end, the leading order ESC reduction of operators within the minimal-coupling four-component approach is carried out. The equivalence of all three approaches within the ESC approximation is proven. It is numerically verified for the NMR nuclear-magnetic shielding tensor taking HX and CH3X (X=Br,I) as model compounds. Formal relations proving the gauge origin invariance of the full relativistic effect on the NMR nuclear-magnetic shielding tensor within the LR-ESC approach are presented.     

Hydrothermally shrunk alumina nanopores and their application to DNA sensing

Hydrothermal treatment of anodized alumina membranes has been known for years and is believed to seal the pores by transforming aluminium oxide into lower density hydroxides. We demonstrate that, at least for 60 nm diameter pores grown from anodization in oxalic acid at 40 V, the hydrothermal treatment significantly shrinks but does not fully seal the nanopores. The pores shrink to a neck of less than 10 nm in diameter and 2-4 microm in length, in which the diffusion coefficient of ions is five orders of magnitude smaller than in the bulk. Because of a high electrolyte resistance through hydrothermally treated shrunken nanopores, they can be used for electrical sensing applications, as demonstrated using the example of DNA sensing. Hybridization of target DNA with a complementary ssDNA covalently immobilized inside the nanopores causes an increase in impedance by more than 50% while a noncomplementary ssDNA has no measurable effect.     

2-iodylphenol ethers: preparation, X-ray crystal structure, and reactivity of new hypervalent iodine(V) oxidizing reagents

2-Iodylphenol ethers were prepared by the dimethyldioxirane oxidation of the corresponding 2-iodophenol ethers and isolated as chemically stable, microcrystalline products. Single-crystal X-ray diffraction analysis of 1-iodyl-2-isopropoxybenzene 8c and 1-iodyl-2-butoxybenzene 8d revealed pseudopolymeric arrangements in the solid state formed by intermolecular interactions between IO2 groups of different molecules. 2-Iodylphenol ethers can selectively oxidize sulfides to sulfoxides and alcohols to the respective aldehydes or ketones.     

Matrices for capillary gel electrophoresis--a brief overview of uncommon gels

This article gives an overview of uncommon replaceable matrices (gels) for capillary gel electrophoresis. This electrophoretic technique is useful mainly for the separation and analysis of biopolymers-nucleic acids and their fragments, and proteins/peptides. Commonly used gels are not reviewed. Those mentioned and discussed here are gels containing saccharides, newly developed acrylamide-based gels and thermoadjustable viscosity polymers, namely triblock copolymers and grafted polyacrylamide.     

On the motion of a heavy rigid body in an ideal fluid with circulation

We consider Chaplygin's equations [Izd. Akad. Nauk SSSR 3, 3 (1933)] describing the planar motion of a rigid body in an unbounded volume of an ideal fluid while circulation around the body is not zero. Hamiltonian structures and new integrable cases are revealed; certain remarkable partial solutions are found and their stability is examined. The nonintegrability of the system describing the motion of a body in the field of gravity is proved and the chaotic behavior of the system is illustrated.     

A Representation of Lattice Effect Algebras by Means of Right Near Semirings with Involution

Since every lattice effect algebra decomposes into blocks which are MV-algebras and since every MV-algebra can be represented by a certain semiring with an antitone involution as shown by Belluce, Di Nola and Ferraioli, the natural question arises if a lattice effect algebra can also be represented by means of a semiring-like structure. This question is answered in the present paper by establishing a one-to-one correspondence between lattice effect algebras and certain right near semirings with an antitone involution.     

Efficient and practical method for the synthesis of hydrophobic azines as liquid crystalline materials

A series of hydrophobic symmetrical azines: 1,2-bis[4-(n-alkoxy)benzylidene]hydrazine (where, n-alkoxy: O(CH₂)_nH, n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, or 18) have been prepared following an efficient and practical method. These compounds have been synthesized via the condensation reaction of hydrazine hydrate and appropriately 4-(n-alkoxy) benzaldehydes in acidic medium under ambient conditions. The prepared organic compounds have been characterized and their structures were elucidated depending upon micro-elemental analysis and spectral data (IR, UV-Vis, ¹HNMR, ¹³C{¹H}NMR, 2D ¹H-¹H-cozy, 2D ¹H-¹³C-HSQC, and mass spectra). Liquid crystalline behavior of the prepared compounds was studied using polarized light optical microscopy and differential scanning calorimetry techniques. This study revealed that all the compounds displayed enantiotropic liquid crystal properties, exhibiting smectic and nematic mesophases.