Materials Literature
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Reactions of VCl 3 (THF) 3, bpy, and NaO 2 CR (R = Et, Ph; bpy = 2,2‘-bipyridine) in a 1:1:3 ratio in Me 2 CO give [V 4 O 2 (O 2 CR) 7 (bpy) 2 ](ClO 4 ) (R = Et, 1; R = Ph, 4 ) following addition of NBu n 4 ClO 4 . Use of 4,4‘-dimethyl- or 5,5‘-dimethylbipyridine (4,4‘-Me 2 bpy and 5,5‘-Me 2 bpy, respectively) and R =…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTElectropolymerization of Acenaphtho[1,2-k]fluoranthene Derivatives: Formation of a New Conductive Electroactive Electrochromic Hydrocarbon Ladder PolymerJeff D. Debad and Allen J. BardView Author Information Department of Chemistry and Biochemistry The University of Te…
The instability and periodic deformation of bilayer membranes during freezing processes are studied as a function of the difference of the shape energy between the high and the low temperature membrane states. It is shown that there exists a threshold stability condition, bellow which a planar configuration will be de…
A first principles theory of inelastic tunneling between a model probe tip and an atom adsorbed on a surface is presented, extending the elastic tunneling theory of Tersoff and Hamann. The inelastic current is proportional to the change in the local density of states at the center of the tip due to the addition of the…
This report describes the synthesis, characterization, and in vivo testing of several bifunctional contrast-enhancing agents for optical and magnetic resonance imaging (MRI) of experimental animals. These new agents integrate the advantages of both techniques since they can be visualized simultaneously by light and MR…
1. General Characteristics of Structural Phase Transitions in Crystals.- 1.1 First- and Second-Order Structural Phase Transitions.- 1.2 Structural Phase Transitions of Displacive and Order-Disorder Types.- 1.3 The Domain Structure.- 1.4 Ferroelectric Phase Transitions.- 1.5 Basic Types of Ferroelectric Crystals.- 2. P…
In the same thermogravimetric analyzer (TGA) under identical conditions, samples of pure, ash-free cellulose (i.e., Avicel PH-105, Whatman CF-11, Millipore ash-free filter pulp, and Whatman #42) obtained from different manufacturers undergo pyrolysis at temperatures which differ by as much as 30 °C. Thus, the pyrolysi…
Stable monolayers of soluble parent polypyrrole (Ppy) and mixed monolayers of cadmium stearate and Ppy were studied for the first time using surface pressure and surface potential isotherms. Ppy was obtained by chemical polymerization of the pyrrole monomer in the presence of dodecylbenzene sulfonic acid and character…
Polarized optical absorption and emission measurements are used to locate and assign 95 crystal-field energy levels split out of the 4f( )(8) electronic configuration of Tb(3+) in single crystals of Na(3)[Tb(oda)(3)].2NaClO(4).6H(2)O (where oda denotes an oxydiacetate ligand). The absorption measurements span the 235-…
Doped group 12 metal sulfides are important materials in the phosphor display industry. Control over the host lattice phase, composition, and dopant concentration is crucial for controlling the luminescence characteristics of these materials. Ternary thin films of Cd x Zn 1 - x S and ZnS:Mn were deposited by aerosol-a…
A series of monolithic poly[methyl methacrylate- co -3-(trimethoxysilyl)propyl methacrylate]−silica hybrid materials have been prepared via the sol−gel reactions. The fracture surfaces of the materials were systematically examined with atomic force microscopy (AFM) as a function of the silica content from ∼23 to 100 v…
New soluble polyimides were prepared from a series of diamines and a tetracarboxylic dianhydride with a benzhydrol unit, 3,3‘,4,4‘-benzhydrol tetracarboxylic dianhydride (BHTDA), by one-step method polymerization. The diamines containing flexible units, bulky substituents, and/or noncoplanar conformation unit were pre…
Theoretical considerations of the molecular hyperpolarizabilities (β) of donor−acceptor substituted aromatic molecules show that the transfer of a proton from the electron-donor group of an acid to the electron acceptor group of a base could increase β for both resulting ionic species relative to the corresponding neu…
A series of alkyl-substituted and unsubstituted poly(3,4-alkylenedioxythiophene)s were synthesized electrochemically using 3,4-alkylenedioxythiophene derivative monomers where either the size of the alkylenedioxy ring or the nature of the pendent group was varied. The specific systems studied include 3,4-ethylenedioxy…
This four-volume reference aims to provide information on the basic principles of both low- and high-molecular weight materials, as well as the synthesis, characterization, modification, and applications (such as in computer displays or as structural materials) of all types of liquid crystals. Volume 1, for example, d…
Hydroxypropyl methylcellulose acetate succinate (HPMCAS) is a new enteric coating material developed by Shin-Etsu Chemical Co., and is marketed under the trade name Shin-Etsu (AQOAT® [49]. It is available in three grades: AS-L(F or G), AS-M(F or G), and AS-H(F or G), corresponding to an average succinyl to acetyl subs…
X-ray photoelectron spectroscopy, XPS, was used for the characterization of electrically conducting polymeric materials. In the spectrum of polypyrrole, PPy, the Nls region exhibits two peaks, at 402.0 and 399.8 eV, corresponding to -N+ - and -N-moieties, respectively. The intensity of the N+ peak decreases as the mat…
By a combination of Q-band pulsed ENDOR (electron nuclear double resonance) and X-band ESEEM (electron stimulated echo envelope modulation) techniques, we have determined the hyperfine tensors for ethylene (C1) and cyano (C2) carbons and N, of [Ni(mnt)(2)](-), along with the quadrupole tensor for nitrogen. These measu…
The changes in chemical states and composition of the surface region of a Ag 2 CO 3 powder at various stages during thermal decomposition have been examined using X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). The near-surface region of the as-received powder consists primarily of Ag 2 C…
The collision of two equi-sized drops immersed in an immiscible liquid phase undergoing a shear flow in a parallel plate apparatus has been investigated over a range of capillary numbers. The drops were observed along the vorticity direction of shear flow by video enhanced contrast optical microscopy. Images of the co…