Synthesis of tetrameric and hexameric cyclo-porphyrins
The synthesis of tetrameric and hexameric porphyin dericatives is reported; these species can act as models of multi-tetrapyrrole aggregates in biological systems.
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Analysis of Electric Field Induced Deformations in a Nematic Liquid Crystal for any Applied Field
For the first time, expressions are presented which enable us to calculate the reorientation of the nematic director under the influence of an applied voltage of any magnitude. The mathematical techniques developed are extended to study the capacitance of a nematic layer under any magnitude of applied voltage. The cal…
X-Ray structural study of [Fe(saltrien)]X (X = Br·2H 2 O, BPh 4 or PF 6 ). Origin of unusual magnetic behaviour of the spin-crossover complex [Fe(saltrien)]PF 6
The crystal structures of three six-co-ordinate iron(III) complexes; [Fe(saltrien)] Br·2H2O (low-spin)(1), [Fe(saitrien)]BPh4(spin-crossover)(2), and [Fe(saitrien)]PF6(spin-crossover)(3) have been determined by X-ray analysis at 293 K, where H2, saitrien denotes the Schiff base derived from salicyiaidehyde and triethy…
Electrooptics of a Thin Ferroeiectric Smectic C* Liquid Crystal Layer
The form of ferroelectric smectic C* electrooptical response vs the layer thickness and the angle β between the polarizer and analyser is investigated. The criterion of the smectic C*-switching rate is propozed and the method for the rotational viscosity measurements is developed.
Neutron Powder Diffraction Profile Refinement Studies on Ca11.3Al14O32.3 and CaClO(D0.88H0.12).
Affinement de la structure des composes non stœchiometriques Ca 12−x Al 14 O 33−x jusqu'a 10,53% pour Ca 11,3 Al 14 O 32,3 . Affinement de la structure de CaClO(D 0,88 H 0,12 ) jusqu'a 19,6%, valeur elevee a cause de la presence de l'impurete H
Long-Term Corrosion and Deuterium Uptake in CANDU-PHW Pressure Tubes
Recent examinations of cold-worked Zircaloy-2 and cold-worked Zr-2.5Nb pressure tubes from CANDU-PHW reactors have extended the corrosion and deuteriding data for these materials up to 5600 effective full power days (efpd), the longest published exposure for these materials in reactor. The examinations have demonstrat…
Deformation and Fracture Properties of Neutron-Irradiated Recrystallized Zircaloy-2 Cladding under Uniaxial Tension
Sufficient evaluation of the changes in mechanical properties, such as elastic, plastic, and failure properties, due to neutron irradiation in service is required to precisely predict fuel performance. This paper presents the results of the uniaxial tensile tests performed for recrystallized (850 K, 2.5 h) Zircaloy-2…
Computer simulation of current density profiles in focused ion beams
We have made a computer simulation of the target current density in our single-lens focused ion beam column. This column images at unity magnification the virtual source of a liquid metal ion source. We simulate the nonlaminar properties of the emitted ions with a two-dimensional function f (r,r′) that represents the…
The Origin and Possible Implications of Surface Stress on Metals
The origin of surface stress on metals is discussed. Self-consistent pseudo-potential calculations of the surface stress tensor at the aluminium [111] and [110] surfaces are reported. In both cases the stress is tensile, favouring contraction in the plane of the surface. The results for aluminium are compared with tho…
Synthesis and characterization of a new series of iron(II) single-face hindered porphyrins. Influence of central steric hindrance upon carbon monoxide and oxygen binding
A series of single-face hindered porphyrins has been synthesized from 5,10,15,20-tetrakis-(o-aminophenyl)porphyrin having one ‘handle’ and two pivaloyl ‘pickets’ as substituents in order both to vary the cavity size and to hold the handle in a central position. They have been characterized from the analysis of the 1H…
Nondirect transitions in variable-temperature angle-resolved photoemission from metals
Temperature-dependent angle-resolved photoemission spectra have been obtained from Cu(001) for normal-emission conditions corresponding to direct transitions originating from various points along the \ensuremath{\Gamma}--\ensuremath{\Delta}--X line. Photon energies were varied from 40 to 106 eV, and specimen temperatu…
Effect of Metallurgical Variables and Temperature on the Fracture Toughness of Zirconium Alloy Pressure Tubes
This paper summarizes the results from over 300 fracture toughness tests on compact specimens taken from zirconium alloy pressure tubing, primarily Zircaloy-2 and cold-worked Zr-2.5Nb. Test conditions include temperatures from 20 to 300°C, varying hydrogen concentrations and hydride orientations, irradiation at severa…
Distribution Transformer Winding Losses Due to Nonsinusoidal Currents
Increased transformer winding losses are an important consideration in determining the overall impact of harmonic currents in a power system. Frequently, losses due to harmonic currents are assumed to vary with the square of frequency. The purpose of this paper is to compare winding loss calculations from a finite ele…
Effect of chlorination on materials for sea water cooling systems: a review of chemical reactions
The electrode and the chemical reactions likely to occur on electrochlorination of sea water are reviewed. The levels of chlorine required to control fouling and the effects of pressure are also discussed. The reactions of chlorine with both common pollutants and chemical additions present in sea water are reviewed, a…
Use of site-directed mutagenesis to obtain isomorphous heavy-atom derivatives for protein crystallography: cysteine-containing mutants of phage T4 lysozyme
Five different cysteine-containing mutants of the lysozyme from bacteriophage T4 were used to explore the feasibility of using site-directed mutagenesis to generate isomorphous heavy-atom derivatives for protein crystallography. Cysteines 54 and 97, present in wild-type lysozyme, can be readily reacted with mercuric i…
Molecular Weight Distribution of Cellulose by On-Line Size Exclusion Chromatography — Low Angle Laser Light Scattering Part I: Basic Experiments and Treatment of Data
Article Molecular Weight Distribution of Cellulose by On-Line Size Exclusion Chromatography — Low Angle Laser Light Scattering Part I: Basic Experiments and Treatment of Data was published on January 1, 1987 in the journal Holzforschung (volume 41, issue 2).
Electrical conductivity in hexaalkoxytriphenylenes
Abstract Triphenylenes containing six side‐chains O(CH 2 ) n CH 3 , n 3‐5, have been prepared and doped with iodine. The compounds show mesophases which have been characterised by differential‐scanning calorimetry and small‐angle X‐ray scattering. Samples doped with iodine show an electrical conductivity of 10 −4 ‐1…
Structure and bonding of the lithium tetrahydroborate–tetramethylethylenediamine adduct (TMEDA·LiBH 4 ) 2 , a centrosymmetric dimer containing doubly and triply bridging hydrogen atoms
The title compound, the first alkali metal tetrahydroborate complex to be structurally characterised, has been shown by an X-ray study to be dimeric in the crystal, with each µ2,η3-BH4 group bonding to two metal atoms through one µ2-hydrogen atom apiece and also through one µ3-hydrogen atom; MO calculations at the 6-3…
Conducting polymers from dimethyl-2,2′-bithiophenes
Electrochemical oxidation of symmetrical dimethylbithiophenes with free α-positions yields electroactive polymers with excellent cycling ability.
Oxidation of crystalline UO2 studied using X-ray photoelectron spectroscopy and X-ray diffraction
The oxidation of the (111) surface of crystalline UO2via U3O7 to U3O8 has been studied by X-ray photoelectron spectroscopy and X-ray diffraction. Oxidation was carried out at 463 and 573 K in 1 Torr† of oxygen. The formation of UO2+x and U4O9 was not observed under these conditions. Anisotropic growth of U3O8 revealed…