Materials Literature
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Poly(ortho esters) based on 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,10-decanediol, and 1,10-decanediol dilactate were prepared and their hydrolysis in phosphate buffer at 37 °C and pH 7.4 was determined as a function of time. Specifically, kinetics of polymer weight loss, polymer molecular weight chang…
In this paper, we discuss the utility of thin film deposition as a synthetic approach to the realization of new oxide materials. Thin film deposition has been shown previously to be well suited to stabilizing both highly metastable phases and superlattices having unique atomic order which are not attainable via classi…
Grafted adsorbing polymers are investigated with the Scheutjens−Fleer self-consistent field model. The surface pressure of such systems is calculated numerically and semiquantitative agreement is found with experimental surface pressure isotherms of PS−PEO diblock copolymers at the air/water interface. Scaling relatio…
Two equilibrium intermediates have previously been observed in the urea denaturation of the alpha subunit of tryptophan synthase (alphaTS) from Escherichia coli, an eight-stranded beta/alpha barrel protein. In the current study, a series of amino-terminal fragments were characterized to probe the elementary folding un…
Polyphenylene dendrimers and dendrons can be obtained using [2 + 4]cycloaddition and Knoevenagel cyclocondensation in a convergent approach.
The effect of fatigue on the electrical properties of sol-gel derived ferroelectric barium titanate (BaTiO3) thin films have been investigated. At room temperature, the resistivity, breakdown field, dielectric constant (ε), and loss tangent (tan δ) decreases after fatigue while the coercive field increases. Fatigue al…
The electron spin density distribution at hydrogen atoms of 4-hydroxyimino-2,2,6,6-tetramethylpiperidin-1-yloxyl (4-hydroxyimino-TEMPO), which has recently been shown to act as a molecular ferromagnet at low temperature, was determined in the crystalline phase on the basis of the temperature dependence of the Fermi co…
The increasing interest in designing polymeric compounds has focused this work on the synthesis and magnetostructural characterization of three 1-D compounds of general formula [M(NCS)2bpa2] [M = Fe, Co, Ni and bpa = 1,2-bis(4-pyridyl)ethane] which exhibit double bpa bridges between metallic cations. X-Ray single crys…
We have studied the coupling of aggregation and crystallization in a mixture of colloidal spheres and colloidal rods. Taking advantage of specially prepared fluorescent silica spheres we are able to investigate this process at the particle level by fluorescense confocal microscopy. We find that above a limiting concen…
A series of D2-symmetric chiral trans-dioxoruthenium(VI) porphyrins can effect enantioselective epoxidation of trans-β-methylstyrene in up to 70% ee, and 76% ee is attained for the oxidation of cinnamyl chloride; the facial selection for the trans-alkenes epoxidation is explained by a ‘head-on approach’ model.
The diffusion and bonding of NOx (x=1, 2) and Cu2+ species in zeolites are reviewed, based mainly on our own research. The molecular motion of adsorbed NO2 has been examined with EPR in several zeolite samples and analyzed using the slow-motional EPR theory. In X- and Y-type zeolites the broadening of the spectra with…
Polarization and morphological characteristics of thin ZnO films deposited on tin‐coated glass electrodes are presented. The films were obtained at a low temperature by an electrolytic process, where the cathode potential is an important control variable. The process is also promising as an electrochemical doping tech…
Regioregular poly(3-alkoxy-4-methylthiophene)s bearing crown ethers of different sizes (12-crown-4), PT12C4; and (15-crown-5) PT15C5) have been synthesized and their thermochromic and ionochromic behaviors investigated. These polythiophene derivatives exhibit a highly conjugated form in the solid state at room tempera…
Template directed reaction of dialdehydes and (R,R)- or (S,S)-1,2-diaminocyclohexane affords a practical route to chiral, metal-free macrocyclic salen dimers which have a novel calixarene-like structure and show catalytic activity for enantioselective epoxidation of unfunctionalized alkenes in the presence of MnIII–Na…
The infrared reflectivity of a ${\mathrm{La}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}$ single crystal is studied over a broad range of temperatures (78--340 K), magnetic fields (0--16 T), and wave numbers $(20--9000{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}).$ The optical conductivity gradually changes from a Drude…
On the origin of the non-exponential behaviour of the -relaxation in glass-forming polymers: incoherent neutron scattering and dielectric relaxation results , J Colmenero, A Arbe, A Alegría, M Monkenbusch, D Richter
Nanoscale materials created from boron nitride (BN) by arc discharge between ZrB 2 electrodes in an N 2 atmosphere have been investigated by electron microscopy. BN nanotubes were formed together with Zr-compound nanoparticles encapsulated in BN cages. Most of the tubes were multilayered and had diameters from 3 to 40…
Monodisperse oligo(para-phenyleneethynylene)s (oligoPPEs) were synthesized by a divergent-convergent synthesis starting from 1,4-dihexyl-2-(3-hydroxyprop-1-ynyl)-5-[2-(triisopropylsilyl)ethynyl]benzene and using the Pd/Cu-catalyzed alkyne-aryl coupling. The groups hydroxymethyl (HOM) and triisopropylsilyl (TIPS) funct…
Dimethyldodecylammonium chloride functionalized poly(propylene imine) generation 3 dendrimers have been synthesized and proven to have strong antibacterial properties.
The first synthesis and Z-scan measurements of an octupolar polymer with off-resonant third order nonlinear optical properties are discussed; two other new molecular thiophene-based octupoles with similar nonlinearities are also reported.