Materials Literature
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We have used density functional calculations on model peptides to study conformational effects on (15)N, (13)C alpha, (13)C beta, and (13)C' chemical shifts, associated with hydrogen bonding, backbone conformation, and side-chain orientation. The results show a significant dependence on the backbone torsion angles of…
The detailed structure of a new dense amorphous ice, VHDA, is determined by isotope substitution neutron diffraction. Its structure is characterized by a doubled occupancy of the stabilizing interstitial location that was found in high density amorphous ice, HDA. As would be expected for a thermally activated unlockin…
The photooxidation of various olefins in homogeneous solution under an oxygen atmosphere, by use of visible light, a dye sensitizer, and an oxygen-transfer catalyst, has been investigated. The oxygen transfer from molecular oxygen to olefin involves the following steps: i) photoinduced singlet-oxygen formation, ii) al…
Atomistic configurations of yttria-stabilized zirconia between 3 and 10 mol % ${\mathrm{Y}}_{2}{\mathrm{O}}_{3}$ were relaxed using the pseudopotential technique. The results showed a phase transition to the cubic (c) $({\mathrm{ZrO}}_{2}{)}_{100\ensuremath{-}x}({\mathrm{Y}}_{2}{\mathrm{O}}_{3}{)}_{x}$ at $x\ensuremat…
L -Tyrosine (C9H11NO3), having morphology of spherulitic needles and long needles, an amino acid constituent of urinary stone, is crystallized in silica gel under suitable pH conditions and by single diffusion and double diffusion methods. The grown crystals were characterized by density measurement, Fourier transform…
Photochromic dithiazolylethenes [1,2-bis(5-methoxy-2-phenylthiazol-4-yl)perfluorocyclopentene (1a) and (5-methoxy-2phenylthiazol-4-yl)-2-(5-methyl-2-phenylthiazol-4-yl)perfluorocyclopentene (2a)] having methoxy substituents at the reaction centers were synthesized and their photochromic reactivity was compared with 1,…
A cyclam-like macrocycle has been synthesized with a pendant arm containing a dansylamide group. In the corresponding nickel(II) complex, binding of the pendant arm to the metal is pH controlled. In particular, at pH 4.3, the sulfonamide group deprotonates and coordinates the NiII center, giving rise to a complex of t…
Four new porphyrin derivatives are described: one (1) with a methoxyphenyl group and three pyridinium units (for comparison only), and three others with either adenine (2, 3) or thymine (4) bases. The synthetic strategies vary from known literature procedures in that the methylation of pyridinium subunits takes place…
Density functional theory (DFT) was applied to describe the magnetic and electron-transfer properties of dinuclear systems containing the [MnO2Mn]n+ core, with n=0,1,2,3,4. The calculation of the potential energy surfaces (PESs) of the mixed-valence species (n=1,3) allowed the classification of these systems according…
A novel method, combining chemical vapor deposition and pyrolysis of trimethoxyborane under ammonia atmosphere, has been developed to synthesize spherical boron nitride particles with a uniform diameter distribution from 50 to 400 nm; chemical composition and high-resolution transmission electron microscopy analyses i…
A diffuse interface model for the one-phase Hele–Shaw problem is derived from a gradient flow characterization due to Otto (1998 Arch. Rat. Mech. Anal. 141 63). The resulting dynamical model yields a generalized form of Darcy's law, and reduces to a degenerate version of the well-known Cahn–Hilliard equation. Formal a…
[Fe(hyptrz)3](4-chloro-3-nitrophenylsulfonate)22 H2O (1; hyptrz=4-(3-hydroxypropyl)-1,2,4-triazole) has been synthesized and its physical properties have been investigated by several physical techniques including magnetic susceptibility measurements, calorimetry, and Mössbauer, optical, and EXAFS spectroscopy. Compoun…
A facile synthesis of highly soluble, axially substituted titanium(IV) phthalocyanines is described. The reaction of tetra-tert-butylphthalocyaninatotitanium oxide tBu4PcTiO with the chelating agents 3a−3i containing oxygen or sulfur as donor atoms leads to the formation of axially substituted tBu4PcTiX (X = functiona…
The influence of electric field on crystal nucleation in a saturated solution has been studied both theoretically and experimentally. The classical equations for nucleation have been used to determine the free energy of formation, critical radius of the cluster and the concentration of the critical nuclei. The theory…
The photocontrol of the alignment of aqueous solutions of an anti-asthmatic drug, disodium chromoglycate (DSCG), as a lyotropic liquid crystal (LLC), was performed by irradiation of a thin film of (4-phenylazophenyl methacrylate) with linearly polarised light. The addition of a non-ionic surfactant to the LLC is a nec…
Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavi…
Iminodiacetate resorc[4]arene is shown to produce gels that are pH-reversible. The gels formed are clear and stable to inversion. (The gels are not stable above a certain temperature, which varies with concentration.) When the pH of an iminodiacetate resorc[4]arene solution (concentration > 7.6 mM) is lowered to below…
The surface-mediated alignment control of a lyotropic liquid crystal (LLC) of aqueous solutions of a water-soluble dye, C. I. Direct blue 67, by using thin films of poly(4-phenylazophenyl methacrylate) as a command surface is described. Concentrated aqueous solutions of the dye in the presence of a non-ionic surfactan…
The ${L}_{2,3}$-edge spectra of Ru and Mn in the ${\mathrm{SrRu}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}{\mathrm{O}}_{3},$ $0<~x<~0.5,$ system reveals the coexistence of a mixed-valence redox pair involving both ${\mathrm{Mn}}^{3+}/{\mathrm{Mn}}^{4+}$ and ${\mathrm{Ru}}^{4+}/{\mathrm{Ru}}^{5+}.$ This influences a l…
A detailed study of the morphological changes that occur during the ageing of a copper zinc oxide (Cu ∶ Zn 2 ∶ 1), formed by co-precipitation from the nitrates is reported and discussed. Using TEM and STEM-EDS, the composition and morphology of the non-calcined precursor are observed to change from an initial amorphou…