Structure and reactivity of polycyclic cross-conjugated π-electron systems
Abstract
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Ideas on the ultrastructural organization of the cell wall components
Abstract The wood cell wall is composed of chemically and structurally different components. The cellulose molecules are smooth long chains, able to aggregate in longitudinal direction to compact fibrils. The polyoses consist of shorter chains with side groups and branching points so that they are not able to aggregat…
Synthesis of porphin analogues containing furan and/or thiophen rings
The preparation of 21-oxa, 21-thia-, 21,23-dioxa-, 21,23-dithia-, and 21-oxa-23-thia-porphins is described. These new porphin analogues have spectral properties similar to those of the porphins, which supports their formulation as aromtic macrocycles. Surprising basicity is displayed by 21,22- and 21,23-dioxaporphins…
Manganese-Activated Luminescence in SrAl[sub 12]O[sub 19] and CaAl[sub 12]O[sub 19]
Manganese‐activated SrAl 12 O 19 and CaAl 12 O 19 phosphors have been prepared under oxidizing and reducing conditions, and by direct cation exchange. The red emission of oxidized phosphor and green emission of reduced phosphor confirm previous assignments to octahedral Mn 4+ and tetrahedral Mn 2+ , respectively. New…
Ionic Conduction in Calcium Doped Polycrystalline Lithium Iodide
The ionic conductivity of polycrystalline lithium iodide containing 0 to 3% (mole) calcium iodide was studied at temperatures between −30° and 130°C.The conductivity increased linearly with the concentration of calcium iodide, and it was concluded that the introduction of calcium ions to the lithium iodide crystals in…
The effect of liquid anhydrous ammonia in the structure and morphology of cotton cellulose
Abstract The effect of liquid ammonia on cotton fabric was studied using x‐ray diffraction (XRD) and electron microscopy. A phase diagram is presented describing the relationship between disordered cellulose, cellulose I, and cellulose III. The transition from cellulose I to III proceeds through the liquid ammonia. Ce…
Studies of the Defect Structure of Nonstoichiometric Cerium Dioxide
The electrical conductivity of sintered specimens of was measured over the temperature range 800°‐1500°C and from 1 to 10 −21 atm of oxygen. Based on the agreement between these experimental data and theoretically derived relations obtained using the law of mass action, the nonstoichiometric defect structure of was in…
Engineering Analysis of the Inelastic Stress Response of a Structural Metal Under Variable Cyclic Strains
Inelastic stress response under strain cycling conditions is analyzed in terms of the three important governing phenomena, namely, memory of prior history, cyclic hardening or softening, and cyclic mean stress relaxation. Independent formulations to describe these respective features consist of a set of hysteresis rul…
Topochemistry. Part XXXIII. The Solid‐State Photochemistry of Some Anthracene Derivatives
Abstract The solid‐state photochemistry of several substituted anthracenes has been investigated with particular reference to the behaviour of polymorphic forms of the monomers. A class of 9‐substituted anthracenes (methyl, methoxycarbonyl, chloro, bromo) crystallising in anti‐parallel, sandwich packing arrangements g…
The Mössbauer effect in tin( II ) compounds. Part XI. The spectra of cubic trihalogenostannates( II )
The 119Sn Mössbauer data and electronic reflectance spectra of the cubic caesium tin(II) halides CsSn Br3 –xClx(x= 0–3) and their behaviour on heating suggest that the non-bonding tin(II) electrons may be involved in a band structure rather than being located in non-bonding molecular orbitals in these materials.
Synthesis and polymerization of bridgehead-substituted bicyclobutanes
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and polymerization of bridgehead-substituted bicyclobutanesHenry Kingston Hall Jr., Claibourne D. Smith, Elwood P. Blanchard Jr., S. C. Cherkofsky, and J. B. SiejaCite this: J. Am. Chem. Soc. 1971, 93, 1, 121–130Publication Date (Print):January 1, 1971Publication H…
Electronic States of Mn2+-Activated Phosphors
The electronic states of Mn 2+ are derived from excitation spectra for eight orange‐to‐red emitting phosphors: ( i ) , ( ii ) , ( iii ) , ( iv ) , ( v ) , ( vi ) , ( vii ) , and ( viii ) . All eight phosphors show complete splitting of at least one electronic level. The observed splittings are compared to the expected…
Thermophysical Properties of Matter - The TPRC Data Series. Volume 2. Thermal Conductivity - Nonmetallic Solids
Abstract : The TPRC Data Series published in 13 volumes plus a Master Index volume constitutes a permanent and valuable contribution to science and technology. This 17,000 page Data Series should form a necessary acquisition to all scientific and technological libraries and laboratories. These volumes contain an enorm…
APPLICATION OF FRACTURE MECHANICS IN THE ANALYSIS OF PAVEMENT FATIGUE
THE PURPOSE OF THIS PAPER IS TO PREDICT THE FATIGUE LIFE OF PAVING MIXTURES IN TERMS OF MATERIAL CONSTANTS, GEOMETRY, BOUNDARY CONDITIONS, AND THE STATE OF STRESS. FATIGUE IS DEFINED IN TERMS OF CRACK INITIATION, INFLUENCES ON CRACK GROWTH, AND CRITICAL STRESS INTENSITY AT THE CRITICAL FAILURE POINT. CRACK GROWTH PARA…
Some properties of water‐soluble hydroxyalkyl celluloses and their derivatives
Abstract The effect of increasing the substitution of water‐soluble hydroxyethyl cellulose (HEC) and hydroxypropyl cellulose (HPC) is to decrease their affinities for water. This is consistent with data given on the cloud point, salt tolerance, surface tension of aqueous solutions, and solubility in organic solvents,…
Correlations between the Kinetics of Electrolytic Dissolution and Deposition of Iron
A synopsis of experimental results on the anodic dissolution of iron is given. From these data the existence of two different reaction mechanisms is proved, of the noncatalyzed (Bockris) mechanism and of the catalyzed (Heusler) mechanism. The current density‐potential relations under steady‐state and nonsteady‐state c…
Studies on the magnetic cross-over in five-co-ordinate complexes of iron(II), cobalt(II), and nickel(II). Part II
The new terdentate ligand 2,6-di(diphenylphosphinomethyl)pyridine forms a series of crystalline complexes, MLX2, with iron(II), cobalt(II), and nickel(II) halides and thiocyanates. Distorted square pyramidal structures are suggested on the evidence of their electronic spectra and other physical properties. Magnetic su…
Measurements of distribution coefficients and barium between carbonate precipitate —Abnormally high values of distribution measured at early stages of carbonate of strontium and solution coefficients formation
The distribution coefficients of Sr and Ba were measured when Mg-poor calcite, Mg-rich calcite or aragonite was precipitated in the calcium bicarbonate solutions containing strontium or barium in trace amounts, MgCl2, NaCl and/or Na-citrate. The abnormally high values of the distribution coefficients were observed ver…
Thermoplastic Polyurethane Hydrolysis Stability
This paper describes the monomer types commonly used in making thermoplastic polyurethane elastomers. It gives chemical structure of the polymers and their general properties. Also de scribed are studies of the hydrolysis of thermoplastic polyurethane elastomers. This will include information on author's choice of hyd…
Plastic deformation of polyethylene II. Change of mechanical properties during drawing
Abstract The crystallinity, elastic modulus, and tensile strength of samples of various draw ratios together with the true stress—strain curves of high‐density polyethylene were determined to establish correlations with morphological changes occurring during deformation. Changes of crystallinity at draw ratios below 5…