Flattened Cone Research Articles

Spectroscopic Characterization and the Effect of Metal Ions on Langmuir-Blodgett Films of Octasubstituted Calix[4]resorcinarenes

Calix[4]resorcinarenes octafunctionalized with methyl α-acetate (CALES) or methyl α-acetamide (CALAM) have been used to form Langmuir-Blodgett (LB) films on several different substrates. Spectroscopic characterization of these species as solids, solutions, and LB films were carried out using FT-IR, FT-Raman, UV-visible, and fluorescence spectroscopies. Considering the spectroscopic evidence, the conformation of both CALES and CALAM in the LB films was found to be the flattened cone. It has been shown that the presence of metal cations in the subphase results in incorporation of cations into the LB film. The film organization of the octafunctionalized calix[4]resorcinarene in the film is determined by the metal cation.

Preparation, structure and stereodynamics of phosphorus-bridged calixarenes

The pyrolysis of several dialkylphosphate ester derivatives of calix[4]arenes yielded the same phosphorus bridged compound7. Under the pyrolytic conditions the phosphate groups may be cleaved or intermolecularly transferred. X-ray crystallography of the bridged calixarenes7 and8 shows that they exist in a chiral ‘flattened cone’ (fc) conformation. The bridged calixarenes undergo in solution a dynamic process with a barrier of about 10.1 kcal mol−1 for7 and8 and 13.1 kcal mol−1 for10, respectively. The dynamic processes result in enantiomerization of the systems. Pyrolysis of partially phosphorylated calix[6]arenes resulted in the formation of two products (11 and12), each consisting of two subunits of three proximal rings bridged by a phosphate group. The rotational barriers for11 and12 are 14.4 and 8.8 kcal mol−1, indicating that the bridged calix[6]arene system12 is appreciably more flexible than11.

Rate limitation in low pressure diamond growth

We performed diamond deposition experiments from a gas phase containing H2, CH4, and sometimes CO, using a microwave plasma ball reactor operating at 400 mbar pressure. The molybdenum substrates were stamped with a suitable tool to form a number of flattened cones on its surface. A strong preference for crystal growth on top of the cones was observed. Numerical calculations were used to solve the underlying thermal conduction and diffusion problems. At the substrate, the flow of the active species entering by diffusion from the bulk of the gas phase was balanced by those leaving the system due to incorporation in the crystals. Comparison with the experiments showed that at least 10% of the active species striking the surface are incorporated. Thus, the limitation of diamond growth in our investigation lies in gas phase transport and not in incorporation difficulties at the growing surface.

Dinosaur Teeth from Lameta Group (Upper Cretaceous) of Kheda District, Gujarat

Abstract Theropod and sauropod dinosaur teeth are being described for the first time from Lameta Group (Upper Cretaceous) of Kheda District, Gujarat. Carnosaurian teeth show megalosaurid characters and are placed in Majungasaurus (Megalosaurus)crenatissimus and (?) Megalosaurus. Five morphological types of (?) Megalosaurus teeth have been distinguished which vary from laterally compressed flattened cones to recurved ones having serrations on anterior/posterior margins and directed either at right angles or obliquely to the margins. The sauropod dinosaur teeth are tentatively placed in Titanosaurus and described as a new species viz., (?) Titanosaurus rahioliensis.

Elatides harrisii, sp. nov., from the lower cretaceous of liaoning, China

A new species of the taxodiaceous genus Elatides, E. harrisii sp. nov., is described from the Lower Cretaceous of Liaoning, China. Its leafy shoots bear helically disposed, almost straight leaves with thin, epistomatic cuticles; the leaves are four-angled in transverse section and have a large resin duct. The female cone is terminal and is composed of dorsiventrally flattened cone scales with a long, acuminate, free distal end, the cuticles of which are essentially similar to those of the leaves. The ligule has a toothead distal margin. The seed is fragmentary; it has a thin outer cuticle of the integument and three cutinised layers inside the stone. There is a well developed pollen chamber and the apex of the nucellus forms a beak-like projection. The male cones are enclosed by bracts which resemble the leaves in cuticular structur. There are 4–5 pollen sacs per scale and the pollen grains are monoporate when well developed. Elatides harrisii is one of the most completely known species of Elatides so far described and is compared in detail with the European species. Other published occurrences of the genus in China are summarized and discussed.

Pityostrobus mcmurrayensis sp.nov., a permineralized pinaceous cone from the Cretaceous of Alberta

A new pinaceous species is described from the Early Cretaceous (Albian) McMurray Formation of Alberta. The cone is partially lignitic with permineralized ovules, 13 cm long × 4 cm wide, and occurs in a siliceous sandstone matrix. Thin sections were made after embedding with bioplastic and infiltration of cut faces with epoxy. Externally the helically arranged flattened cone scales resemble those of extant Picea. Scales bear two inverted, winged ovules containing shrunken nucellar and megagametophyte tissue. The cone axis is slender and contains small wedges of secondary xylem lacking resin canals. Vascularization of the cone–scale complex is similar to the non-Pinus species of the Pinaceae with bract and scale traces separate at their origins. One large abaxial resin canal, 1 mm in diameter, accompanies the traces out into the scale for 1 cm before branching. Two large bundles of sclerenchyma accompany the scale vascular tissue and may have served to open the cone at maturity. The bract, small and triangular in outline, has a terete trace and two lateral resin canals. Cone and seed structure are closely comparable to fossil pinaceous genera Pseudoaraucaria and Pityostrobus and the non-Pinus genera of the extant Pinaceae.

Form, mechanism, and control of dolerite intrusion near Hobart, Tasmania

Abstract The Jurassic dolerites around Hobart were probably emplaced during four or five injection periods. Each period has produced a series of interlinked stepped sheets with the overall form of an axially flattened cone. Feeders were dyke‐like, although some were pipes or wedges from dykes. Dislocation by fracturing was followed by hydrostatic intrusion. Controls were imposed on the intrusion by roof load, magma pressure, and barrier formations. Early injections are believed to have been intruded low in the rock column, later ones at high levels.

II.—On the Dentition of the Palate in the South African Fossil Reptile Genus Cynognathus

The Cynodont reptilia from the Lower Karroo rocks of South Africa, characterized by relatively large incisors and relatively small, sharp-pointed, molar teeth, were grouped under the type genus Lycosaurus as Lycosauria. The removal of matrix from the palate of Ælurosaurus showed that in one member of the group at least the palate carries patches of teeth, each of which has the form of a small blunt flattened cone. From the fact that no Cynodont skull is available in which the mandible is free from the head, the nature of the palatal dentition is imperfectly known.

A description of the teeth of the Delphinus Gangeticus

In the 7th volume of the Asiatic Researches, published in 1781, Dr. Roxburgh describes the Delphinus Gangeticus , but gives a very imperfect account of its teeth; nor is any detailed account of them given in any other work. As the jaws and teeth of this species of Delphinus form its most remarkable character, Sir Everard thinks the subject of sufficient interest to the comparative anatomist and geolo­gist, to be laid before this Society. These teeth, as in the whole tribe, generally have the rudiments in the gums, from which the teeth grow in both directions; upwards through the gum in the form of the point of a flattened cone, which is coated with enamel, and downwards towards the jaw, increasing in breadth, but not in thickness, till it is imbedded in the substance of the jaw itself. The lower portion has no enamel; the number of teeth is, as described by Dr. Roxburgh, 120.