Materials Literature
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We report the electron transport studies in the rhombohedral LaMn 1- x Al x O 3+δ series (0⩽ x ⩽20%) of samples. Though all the samples are ferromagnetic below a transition temperature ( T C ), only the samples with x ⩽5% exhibit a metal-insulator transition (MIT) at T C while the samples with x ⩾10% are all semicondu…
The explosive charge within a landmine is the source for a mixture of chemical vapors that form a distinctive 'chemical signature' indicative of a landmine. The concentration of these compounds in the air over landmines is extremely low, well below the minimum detection limits of most field- portable chemical sensors.…
Nature tries to minimize the surface area of a soap film through the action of surface tension. The process can be understood mathematically by using differential geometry, complex analysis, and the calculus of variations. This book employs ingredients from each of these subjects to tell the mathematical story of soap…
Adsorption of hydrogen sulfide on fifteen samples of activated carbons (unmodified and catalytic with introduced basic nitrogen groups) was studied using inverse gas chromatography (IGC) at infinite dilution. Porous structure of carbons was evaluated using sorption of nitrogen. From the retention volume measured in IG…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTChemical Modification of Chitosan. 3. Hyperbranched Chitosan−Sialic Acid Dendrimer Hybrid with Tetraethylene Glycol SpacerHitoshi Sashiwa, Yoshihiro Shigemasa, and René RoyView Author Information Department of Chemistry, University…
In this paper, we examine collective and self-diffusion properties of dispersions of spherically shaped colloidal particles at intermediate and long times. Our analysis is based on a fully self-consistent (rescaled) mode coupling theory (MCT) adjusted to describe the overdamped dynamics in concentrated suspensions of…
The photoluminescence (PL) at 300 and 90 K from the mesoporous silicas (MSs) [ordered (MCM-41) and disordered (DMSs)] of variously sized pores induced either by ArF laser light (λ exc = 193 nm) or by Nd:YAG (yttrium−aluminum−garnet) laser light (λ exc = 266 nm) was studied. The spectra were measured in both convention…
Zinc porphyrin receptors bearing 12 ester groups in the meso phenyl groups (1-3) were prepared, and binding of amines and alpha-amino esters was studied with emphasis on the binding mechanisms. The X-ray crystallographic analysis of 5,10,15,20-tetrakis(2, 6-bis(carbomethoxymethoxy)-4-carbomethoxyphenyl)porphyrin (free…
Pyrolysis of hyperbranched poly[1,1‘-ferrocenylene(methyl)silyne] ( 5 ) yields mesoporous, conductive, and magnetic ceramics ( 6 ). Sintering at high temperatures (1000−1200 °C) under nitrogen and argon converts 5 to 6N and 6A, respectively, in ∼48−62% yields. The ceramization yields of 5 are higher than that (∼36%) o…
A mechanism for the formation of polyelectrolyte multilayers is proposed. All of the experiments on such systems show that there is strong interpenetration of consecutive layers. We explain the very strong stability of the multilayers by the complexation between polyelectrolytes of opposite signs. Scaling laws on bulk…
State-of-the-art first principles calculations based on density functional theory were performed on CH_3(CH_2)_{n-1}S-Au(111) systems. We show that the adsorption site of methylthiolate at low coverage on the Au(111) surface is the fcc site, not the hcp site as has been recently reported. Further, we report results fo…
We study, both numerically and variationally, the interplay between different types of elementary excitations in the model of a spin chain with anisotropic spin-orbit coupling, in the vicinity of the "dimer line" with an exactly known dimerized ground state. Our variational treatment is found to be in a qualitative ag…
In the field of quantum chaos, the study of energy levels plays an important role. The aim of this review paper is to critically discuss some of the main contributions regarding the connection between classical dynamics, semi-classical quantization and spectral statistics of energy levels. In particular, we analyze in…
Dion−Jacobson phases are layer perovskites of the general formula A‘[An-1BnO3n+1], where A‘ is typically an exhangeable alkali or alkali earth ion. Because of their low layer charge density, acid-exchanged Dion−Jacobson phases are easily exfoliated to make single-sheet colloids. When the conditions temperature and pH…
We present the results of Monte Carlo simulations of a model of a $γ$-Fe$_2$ O$_3$ (maghemite) single particle of spherical shape. The magnetic Fe$^{3+}$ ions are represented by Ising spins on a spinel lattice that consists on two sublattices with octhaedral and tetrahedral coordination with exchange interactions amon…
We verify whether the previously developed model of a KD2PO4 crystal, with the shear strain eps6 taken into account, is able to describe the longitudinal electric field E3 influence on the KH2PO4 family ferroelectrics. Major effects of the strain eps6 are splitting of the Slater energies of the short-range correlation…
The statistical mechanical ensemble associated with molecular-dynamics (MD) simulations with the weak coupling (WC) thermostat proposed by Berendsen et al. [J. Chem. Phys. 81, 3684 (1984)] is analyzed. Using a generalized Liouville equation, an approximate equilibrium distribution function in the configurational space…
C−H bond activations of benzene and methane by M( η 2 -O 2 CH) 2 (M = Pd or Pt) are theoretically investigated with density functional theory (DFT), MP2-MP4(SDQ), and CCSD(T) methods. The C−H bond activation of benzene takes place with activation energies ( E a ) of 16.1 and 21.2 kcal/mol and reaction energies (Δ E )…
Ozone is a unique species whose chemistry has a profound impact in many areas of our society. It is well known as a beneficial constituent of the upper atmosphere which shields living organisms fro...
Stereochemistry can be said to have begun in 1848 when Pasteur observed that crystals of sodium ammonium tartrate obtained by slow recrystallisation at room temperature were of two mirror image crystallographic forms. He was able to pick out these two forms by hand and show that solutions of equal concentration caused…