Lithocodium aggregatum Elliott et Bacinella irregularis Radoicic de l'Aptien de Teruel (Espagne); deux stades de croissance d'un seul et meme organisme incertae sedis
Abstract Possibly algal, Bacinella young stage of Lithocodium
Materials Literature
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The Diffusivity and Solubility of Oxygen in Liquid Tin and Solid Silver and the Diffusivity of Oxygen in Solid Nickel
T H E e l e c t r o c h e m i c a l d e t e r m i n a t i o n of the d i f fus iv i ty of oxygen in so l id m e t a l s us ing a s t a b i l i z e d z i r c o n i a s o l i d e l e c t r o l y t e ce l l of c y l i n d r i c a l g e o m e t r y was f i r s t c a r r i e d out by R i c k e r t and S te ine r I who d e…
X-Ray structure analyses and magnetic correlation of four copper(II) complexes
Magnetic properties of a series of antiferromagnetic binuclear complexes correlate closely with their structures, as determined by single crystal, X-ray diffraction analyses.
Melting rates of crystalline polymers under shear conditions
Abstract The melting of solids under shear conditions is an important operation in the processing of most thermoplastics. In this study, solid blocks of high density polyethylene were melted on a hot, moving surface over a range of surface temperatures and velocities. The conservation equations for mass, momentum, and…
Thermal decomposition of alkali metal hexafluorophosphates
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal decomposition of alkali metal hexafluorophosphatesThomas C. Ehlert and Ming-Ming HsiaCite this: J. Chem. Eng. Data 1972, 17, 1, 18–21Publication Date (Print):January 1, 1972Publication History Published online1 May 2002Published inissue 1 January 1972https://pubs.acs…
Dimethyl Δ 3 -1,2-diazetine-1,2-dicarboxylate: a new four-membered 6π-ring system
Dimethyl Δ3-1,2-diazetine-1,2-dicarboxylate has been prepared by photolysis of the 1 : 1 adduct of 2,5-dimethyl-3,4-diphenylcylopenta-2,4-dienone and 2,3-dimethoxycarbonyl-2,3-diazabicyclo[2,2,0]hex-5-ene; this new ring system formally satisfies the Hückel (4n+ 2) rule, but no pronounced stability was observed, and th…
Extended chain crystals of linear high polymers
Abstract
Accurate calculations of properties of the two-tube electrostatic lens. I. Improved digital methods for the precise calculation of electric fields and trajectories
Di g it a l me th ods of hi g h prec is ion ha ve bee n de ve loped for th e c alculation of e lec tri c fi e lds a nd tra jectori es in e lec tros tati c le nses a lld a comput e r prog ra m was wri tt e n to app ly th ese me t hods to th e two-tube le ns . Th e ill c reased prec is ion res uit s fro m til(" use of n…
A.C. and D.C. electrical conductivity in amorphous arsenic trisulphide films
It is shown that measurements of a.c. and d.c. conductivity in undoped amorphous As2S3 films differ in several respects from those reported in other chalcogenide glasses. Experiments show conclusively that the a.c. lows in this material are due to a bulk-controlled process. The frequency-dependent but temperature-inde…
Influence of Grain Size on the Portevin-LeChatelier Effect in Al–Mg Alloys
In order to investigate the effect of grain size on Portevin-LeChatelier yielding, tensile tests were performed on Al–0.55 and 1 at% Mg alloys having various grain sizes. In a temperature range of −20°∼+40°C and a strain rate range of 3.3×10−5∼1.7×10−3/sec, the value of activation energy for the P–L effect was found t…
The photochemical oxidation of 4-arylazo-1-naphthols
The 4-arylazo-1-naphthols (1) undergo self-sensitised or dye-sensitised photo-oxidation in solution, giving 1,4-naphthaquinone and the aryl-diazonium ion.
Carbon Thermal Diffusion in the UC 2 ‐C System
Alpha uranium dicarbide disks coated with pyrolytic carbon migrate, relative to the carbon, up a temperature gradient, leaving behind a layer of rejected graphite. A model for the migration process based on solution of carbon at the hot UC 2 ‐C interface, transport across the UC 2 phase by thermal diffusion, and rejec…
Apoverbenone (6,6-dimethylnorpin-3-en-2-one). An investigation into its preparation by dehydrobromination of a sterically hindered bromo-ketone
The dehydrobromination of 3-bromo-6,6-dimethylbicyclo[3,1,1]heptan-2-one has been studied. Treatment with lithium bromide and lithium carbonate in dimethyl sulphoxide gave 6,6-dimethylnorpin-3-en-2-one (apoverbenone) in good yield. From (–)-pin-2(10)-ene, optical purity 91%, we obtained (+)-apoverbenone, [α]D+ 319°(c…
Pyrroles and related compounds. Part XX. Syntheses of coproporphyrins
Coproporphyrin-I has been synthesised by modifications of Fischer's original methods; Coproporphyrin-II has been synthesised by three methods including a variant of the MacDonald method, involving self-condensation of a 5-formylpyrromethane-5′-carboxylic acid. Coproporphyrins-III and -IV and a related porphyrin tricar…
Blue-Green Algae of the Saline Soils of the Punjab
Cultures of blue-green algae of 44 soil samples and 40 samples of naturally growing ones, collected from highly saline soils, moderately saline soils and reclaimed saline soils, were studied in relation to the soil type. It was found that most of the species belonging to Chroococcales, Oscillatoriaceae, Nostoc, Tolypo…
Accurate Calculation of Properties of the Two-Tube Electrostatic Lens II. First-Order Focal Properties and P-Q Curves
Using digital methods, electric fields and paraxial electron trajectories in the two-tube electrostatic lens have been calculated, and the first-order (Gaussian) focal properties accurate to at least 0.1% were obtained for voltage ratios from 1.5 to 50. The results are presented in the form of P-Q (object-image positi…
The Chemistry and Technology of Rubber-Bound and Related Novel Antioxidants
Abstract The discovery that C-nitrosoanilines react with olefins to give p -phenylenediamines has made possible the synthesis of powerful antioxidants from a wide range of naturally occurring and synthetic unsaturated compounds. Simple alkenes, vegetable oils, and factices may be converted to antidegradants whose beha…
X‐Ray and stereochemical studies on xylan diacetate
Abstract By means of x‐ray fiber diffraction, it has been found that xylan diacetate crystallizes with two chains or four residues in a monoclinic cell (space group P 2 1 ): a = 7.64, b = 12.44, c (fiber axis) = 10.31 Å, and γ = 85°. Pairs of residues are related by a twofold screw axis in the c direction. Based on th…
Porphyrins and bile pigments from brominated pyrromethenes
Aetioporphyrin-I (1a) is obtained in 50–60% yield by heating 5-bromo-3,4′-diethyl-3′,4,5′-trimethylpyrromethene perbromide (4a) under reflux in formic acid, surpassing the yields from the established syntheses using the less accessible 5-bromo-5′-bromomethylpyrromethene hydrobromides (2a, b). The 5-bromo-5′-methylpyrr…
Conditions of Formation of Calcite Crystals of Tabular and Acute Rhombohedral Habits
Abstract Calcite crystals are grown under pure conditions by the method of counterdiffusion of calcium and carbonate ions in water. An extension of the diffusion method is used making possible the crystallization of calcite in a medium containing calcium or carbonate ions in excess of their stoichiometric amounts in c…