Materials Literature
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A direct method of surface silyl modification and simultaneous surfactant removal of mesoporous silica is investigated in its physicochemical details. Twelve different silanes of various functionalities are studied. The method employs an alcohol solution of silanes to allow the simultaneous surfactant/silyl exchange p…
The synthesis of nanocomposites via emulsion polymerization was investigated using methyl methacrylate (MMA) monomer, 10 wt % montmorillonite (MMT) clay, and a zwitterionic surfactant octadecyl dimethyl betaine (C18DMB). The particle size of the diluted polymer emulsion was about 550 nm, as determined by light scatter…
The adsorption of volatile organic compounds (VOCs) on the activated carbon, silica gel, and type-13X synthetic zeolite were investigated by a gravimetric adsorption method. The sorbates (VOCs) include benzene, toluene, o -xylene, p -xylene, and m -xylene. The equilibrium isotherm data obtained from this study were fi…
We demonstrate that when a single-walled carbon nanotube is under pressure it undergoes a series of shape transitions, first transforming from a circle to an oval and then from an oval to a peanut. Most remarkably, the ratio of the area of the tube cross sections at the second transition over that at the first transit…
Abstract Spectroscopic [UV–visible and Fourier transform IR (FTIR)] and thermal properties of chemically synthesized polyanilines are found to be affected by varying the protonation media (acetic, citric, oxalic, and tartaric acid). The optical spectra show the presence of a greater fraction of fully oxidized insulati…
The resolution of far-field optical microscopes, which rely on propagating optical modes, is widely believed to be limited because of diffraction to a value on the order of a half-wavelength $λ/2$ of the light used. Although immersion microscopes have slightly improved resolution on the order of $λ/2n$, the increased…
The growth and dynamics of solid surfaces displays a multitude of power law relationships, which are often associated with geometric self-similarity. In many cases the mechanisms behind these power laws are comparatively trivial, and require little more than dimensional analysis for their derivation. The information o…
By employing a real-space formulation of the Kubo-Greenwood equation based on a Green's function embedding technique combined with the fully relativistic spin-polarized Korringa-Kohn-Rostoker method a detailed investigation of the electrical transport through atomic-scaled contacts between two Au(001) semi-infinite sy…
We present a detailed analytical and numerical analysis of the nuclear spin dynamics in parabolic quantum wells. The shallow potential of parabolic quantum wells permits substantial modification of the electronic wave function in small electric fields. The nuclear spin relaxation via the hyperfine interaction depends…
Tridentate/tetradentate Schiff base ligands L(1) and L(2), derived from the condensation of o-vanillin or pyridine-2-aldehyde with N,N-dimethylethylenediammine, react with nickel acetate or perchlorate salt and azide, cyanate, or thiocyanate to give rise to a series of dinuclear complexes of formulas [Ni(L(1))(micro(1…
This paper presents results of first-principles calculations of nuclear magnetic resonance (NMR) parameters: the chemical shielding tensor and the electric field gradient tensor, of some crystalline and amorphous sodium silicate systems. The calculations have been performed using the recently introduced gauge includin…
Rich populations of clusters have been observed after femtosecond laser ablation of bulk silicon in vacuum. Size and velocity distributions of the clusters as well as their charge states have been analyzed by reflectron time-of-flight mass spectrometry. An efficient emission of both neutral silicon clusters Sin (up to…
The simulation study on Frenkel pair creation in vanadium by L.A. Zepeda-Ruiz et al. (Phys. Rev. B 67, 134114, 2003) is criticized for its lack of reference to existing experimental work and for generally inadequate treatment of literature data. Hence, the validity of the ensuing discussion of various results (e.g. th…
From a multiple scale analysis, we find an analytic solution of spherical and cylindrical Poisson-Boltzmann theory for both a 1:2 (monovalent co-ions, divalent counter-ions) and a 2:1 (reversed situation) electrolyte. Our approach consists in an expansion in powers of rescaled curvature $1/(κa)$, where $a$ is the coll…
We report here the first synthesis of pure boron single-wall nanotubes by reaction of BCl 3 with H 2 over an Mg−MCM-41 catalyst with parallel, uniform diameter (36 ± 1 Å) cylindrical pores. The composition of the tubular structures observed in TEM was confirmed by electron energy loss spectroscopy, and the tubular geo…
Isotopic tracer and kinetic studies are used to probe the identity and reversibility of elementary steps required for H 2 O and CO 2 reforming of CH 4 on supported Pt clusters and to demonstrate a rigorous kinetic and mechanistic equivalence for CO 2 and H 2 O reforming, CH 4 decomposition, and water-gas shift reactio…
The flowerlike ZnO nanostructures, which consisted of swordlike ZnO nanorods, have been prepared by a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal process at low temperature (120 °C). The XRD pattern indicated that the flowerlike ZnO nanostructures were hexagonal. Furthermore, the SAED and HRTEM reveale…
A new circular position sensor based on giant magnetoresistances has been developed. The sensing film is an AgCo nanogranular thin film patterned in a circular Wheatstone bridge configuration. This alloy shows a high magnetoresistance (8%) at room temperature within the field generated by an NdFeB permanent magnet tha…
Multilayers of alternately adsorbing poly(allylamine) (PAH) and poly(acrylic acid) (PAA) of opposite charges on silica have been studied by the spin labeling technique, as a function of pH. The two polyelectrolytes have been labeled independently by a nitroxide free radical. Its electron paramagnetic resonance spectru…
A new carbon-13 NMR method is presented for the quantitative determination of monomer sequence distributions and average sequence lengths in propylene−1-butene copolymers. Complete carbon-13 NMR chemical shift assignment was finalized: the peaks corresponding to comonomeric sequence distributions are assigned in terms…