Materials Literature
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A new class of surface-modified dendrimers has been prepared by reactions of 8 equiv of the terpyridine-functionalized polyether monodendrons with a polyhedral oligomeric silsesquioxane (POSS) core. Subsequent reactions of these spherically shaped organic dendrimers with Ru(II)-based precursors afford photo- and redox…
Homogeneous DNA hybridization assay based on luminescence resonance energy transfer (LRET) from a tetradentate beta-diketonate europium chelate, 4,4'-bis(1' ',1' ',1' ',2' ',2' ',3' ',3' '-heptafluoro-4' ',6' '-hexanedion-6' '-yl)-chlorosulfo-o-terphenyl (BHHCT)-Eu(3+) (lambda(ex) = 340 nm and lambda(em) = 615 nm), to…
The electronic structures of a series of carbon nanotubes with different sizes, chiralities, ends, and bond lengths are studied systematically. Their absorption spectra are calculated with the localized density matrix method. The semiempirical model PM3 is employed in the calculation. The nature of optical excitations…
Reaction of M(NO3)2.xH2O (M = Mn, Co, Ni, Cu, Zn) with 3-diphenylamino-4-hydroxycyclobut-3-ene-1,2-dione (diphenylaminosquarate) produces the neutral polymeric species (M[mu-(C6H5)2NC4O3]2[H2O]2)n [M = Mn (1), Cu (2)]; (M[mu-(C6H5)2NC4O3][(C6H5)2NC4O3][H2O]3)n [M = Co (3), Zn (4)]; and in the case of Ni, the salt [Ni(…
The H-bond interaction between the tautomeric cytosine-modeling system, 2-hydroxypyridine (2HP)/2-oxopyridine (2OP), with water is investigated using matrix-isolation FT-IR spectroscopy and ab initio calculations performed with the RHF and MP2 methods and the DFT method with the B3-LYP hybrid functional. Equilibrium s…
Polypropylene (PP) was modified by solid-phase graft copolymerization with maleic anhydride (MAH) and styrene (St), using benzoyl peroxide as the initiator and xylene as the interfacial agent. Effects of various factors such as monomer concentration, monomer ratio, initiator concentration on grafting percentage, and a…
Chemical hydrogels based on poly(vinyl alcohol), PVA, were obtained by reacting telechelic PVA bearing aldehydic groups at both ends of the chain with the hydroxylic moiety of the polymer. These networks were studied by dynamic light scattering around the sol−gel transition threshold. The auto-correlation function, g…
The unprecedented use of polymerizable hydrocarbon tail systems containing 1,3-diene groups for the design of thermotropic and lyotropic liquid crystal (LC) monomers is described. Cross-linkable LC dienes are synthesized by attaching LC core units to modular ω-bromoalka-1,3-diene tails of variable length. These modula…
Au nanoparticles (particle diameter ∼2 nm) prepared by thiocyanate reduction method are too small to exhibit the characteristic surface plasmon band. Addition of Rhodamine 6G (Rh 6G) to the colloidal gold solution brings about significant changes in the absorption spectrum. Two distinct peaks appear at 507 and 537 nm.…
The first-order hyperpolarizabilities of a series of mono-, bi-, and trinuclear organometallic compounds were determined using Hyper-Rayleigh Scattering at 1.06 μm. The molecular nonlinear optical responses (NLO) were investigated for various combinations of iron(II) and iron(III), including mixed-valence iron(II)/iro…
Alzheimer's disease (AD) is characterized by the presence of amyloid-positive senile plaques and tau-positive neurofibrillary tangles. Aside from these two pathological hallmarks, a growing body of evidence indicates that the amount of oxidative alteration of vulnerable molecules such as proteins, DNA, and fatty acids…
Time-dependent density functionals in principle depend on the initial state of the system, but this is ignored in functional approximations presently in use. For one electron it is shown there is no initial-state dependence: for any density, only one initial state produces a well-behaved potential. For two non-interac…
Direct and unambiguous experimental evidence for the magnetic force density being of the form $M\nabla B$ in a certain geometry - rather than being the Kelvin force $M\nabla H$ - is provided for the first time. (M is the magnetization, H the field, and B the flux density.)
We show that nanostructure and resistivity of Pr0.5Ca0.5Mn0.98Cr0.02O3 are sensitive to whether the sample is zero-field-cooled (ZFC) of field-cooled (FC) either in the 'self magnetic field (H = 2 T)' of the electron microscope or under the external magnetic field of 2 T. FC resistivity at H = 2 T is lower than ZFC va…
The current efforts to fabricate non-volatile magnetic recording media with a high areal density is deteriorated by the increasing temporal instability of the stored information. If the stored energy per magnetic particle competes with the thermal energy, spontaneous magnetic reversal processes may occur. Deposition o…
We study the static and dynamic properties of bromine electrosorption onto single-crystal silver (100) electrodes by Monte Carlo simulation. At room temperature the system displays a second-order phase transition between a low-coverage disordered phase at more negative electrode potentials and a c(2x2) ordered phase w…
The hcp-fcc transformation induced in cobalt powder by ball milling at room temperature was studied using the excess Gibbs free energy for the metals, in nanometric form, to calculate the activation energy that the atoms need for the phase transformation to occur. The crystalline component of the nanocrystalline cobal…
Constitutive equations are derived for the viscoelastic response of rubbery polymers at finite strains. A polymer is thought of as a network of long chains connected to temporary junctions. At a random time, a chain detaches from a junction, which is treated at transition from its active state to the dangling state. A…
When two or more atoms bind to a solid surface, the substrate can mediate an interaction between them. In this paper, we use density-functional theory to quantify the substrate-mediated pair interaction between two adatoms on a compressively strained Ag(111) surface and on unstrained Ag(111). On the strained surface,…
Partially deacetylated chitins with different degrees of deacetylation (DD) were prepared by alkaline treatment under homogeneous conditions, and the effect of DD on their solubility was discussed in terms of crystal structure and mode of hydrogen bonding. With an increase in the treatment time, the DD of chitin incre…