Cretaceous-Tertiary findings, paradigms and problems

The asteroid hypothesis has stimulated numerous studies of the paleontological record at Cretaceous/Tertiary time as well as of geological indicators of environmental crisis preserved in the rock record. Both extinctions and geological anomalies often occur at times that do not appear to be synchronous or instantaneous. The record includes paleontological indicators of dinosaurs, terrestrial flora, marine planktonic organisms, and shallow water marine macrofauna and geological phenomena include occurrences of iridium and other platinum metals, trace elements, clay mineralogy, shocked minerals, soot, microspherules, and isotopes of osmium, strontium and carbon. These findings are reviewed in the context of the alternate hypotheses of an exogenic cause, involving either a single asteroid impact or multiple commentary impacts, and an endogenic cause, involving intense global volcanism and major sea level regression

Electrochemical study of 1,3-indandione derivatives of terthiophenes

Properties and behavior of a group of four newly synthesized derivatives of terthiophene and terthienylenvinylene was studied. All four investigated monomers bear a 1,3-indandione substituent at the central thiophene ring and two of them (ThIV, ThIVM) have additional vinyl bonds introduced between the thiophene rings. In addition, ThIM and ThIVM have 5 positions of the two terminal rings blocked with methyl groups. The measurements were done using cyclic voltamperometry (CV) in solutions of 0.1M Bu4NBF4 in CH2Cl2. It was found that ThI and ThIV polymerise easily. CV of ThI reveals a reduction peak resulting probably from the abstraction of a proton. During polymerisation of ThIV a group of peaks is observed indicating its stepwise oxidation process. The polymerisation potential of ThIV was found to be lower than that of ThI which could mean that formation of radical-cation is easier in the former. Stability measurements indicated that polymer films of ThI are electrochemically stable in CH2Cl2 and films of ThIV are not. Efforts to polymerise ThIM and ThIVM failed. Their CVs revealed only peaks coming from oxidation of the monomers, some of which were semi-reversible

Electrochemical and optical aspects of cobalt meso-carbazole substituted porphyrin complexes

A series of cobalt (II) porphyrin complexes modified with carbazole rings at one or more meso positions of the macrocycle were synthesized and characterized as to their spectroscopic and basic electrochemical properties in non-aqueous media. The effect of the number and position (syn and anti) of carbazole groups on the complexes properties were investigated. The comparison was made to cobalt (II) porphyrin containing mesityl groups at the meso-positions. The relation between the site of redox processes in cobalt meso-carbazole substituted porphyrins were analysed. It was shown that the conjugated π-ring system of the porphyrin macrocycle, the cobalt central metal ion and the carbazole peripheral substituents are redox-active

Photoelectrochemical cells based on inherently conducting polymers

This review of photoelectrochemical cells (PECs) based on inherently conducting polymers (ICPs) deals with the mechanisms of operation and the various factors that influence the overall efficiency of PECs. The factors addressed include ICP composition and oxidation state, the use of nanostructured surfaces and interfaces, and the PEC electrolyte and redox mediator

Dynamic deformation of volcanic ejecta from the Toba caldera: Possible relevance to Cretaceous/Tertiary boundary phenomena

Plagioclase and biotite phenocrysts in ignimbrites erupted from the Toba caldera, Sumatra, show microstructures and textures indicative of shock stress levels higher than 10 GPa. Strong dynamic deformation has resulted in intense kinking in biotite and, with increasing shock intensity, the development in plagioclase of planar features, shock mosaicism, incipient recrystallization, and possible partial melting. Microstructures in quartz indicative of strong shock deformation are rare, however, and many shock lamellae, if formed, may have healed during post-shock residence in the hot ignimbrite; they might be preserved in ash falls. Peak shock stresses from explosive silicic volcanism and other endogenous processes may be high and if so would obviate the need for extraterrestrial impacts to produce all dynamically deformed structures, possibly including shock features observed near the Cretaceous/Tertiary boundary

Oaths and Incidental Matters Inferior Courts Initial Review of and Action on Records of Trial Ordering Rehearings-Designating

Th?rc jx~phlet contains a short history of the preparation 0: ' +.he Manual for Courts-Martial, United States, 1951, %%other with brief discussions of the legal and legislative;onsiderations involved in the drafting of the book. With &nor exceptions, the discussions of the various subjects were written by the officers who prepared the initial drafts of the comparable portions of the manual

Extrusion printed graphene/polycaprolactone/ composites for tissue engineering

In this work fibres and complex three-dimensional scaffolds of a covalently linked graphene-polycaprolactone composite were successfully extruded and printed using a melt extrusion printing system. Fibres with varying diameters and morphologies, as well as complex scaffolds were fabricated using an additive fabrication approach and were characterized. It was found that the addition of graphene improves the mechanical properties of the fibres by over 50% and in vitro cytotoxicity tests showed good biocompatibility indicating a promising material for tissue engineering applications

A simple one step process for enhancement of titanium foil dye sensitised solar cell anodes

The photo-conversion efficiency and stability of back-illuminated dye sensitised solar cells with titanium foil based photoanodes are enhanced by a simple nitric acid treatment through which the foil is passivated. This treatment changes the morphology of the titanium foil and increases its electrochemical double layer capacitance