Nitrogen geochemistry of a Cretaceous-Tertiary boundary site in New Zealand

Nitrogen in the basal layer of the K-T boundary clay at Woodside Creek, New Zealand, has an abundance of 1100 ppm, a 20-fold enrichment over Cretaceous and Tertiary values. The enrichment parallels that for Ir and elemental carbon (soot); all decrease over the next 6 mm of the boundary clay. The C/N ratio, assuming the nitrogen to be associated with organic rather than elemental carbon, is approximately 5 for the basal layer compared to 20 to 30 for the remainder of the boundary clay. The correlation between N and Ir abundances appears to persist above the boundary, implying that the N is intimately associated with the primary fallout and remained with it during the secondary redeposition processes that kept the Ir abundance relatively high into the lowermost Tertiary. Apparently the basal layer of the boundary clay represents the accumulation of a substantial quantity of N with an isotopic composition approximately 10 percent heavier than background delta value of N-15 values. If the boundary clay represents an altered impact glass from a meteorite impact than it probably denotes a time period of less than 1 year. Therefore, the changes in nitrogen geochemistry apparently occurred over a very short period of time. The high abundance of N and the correspondingly low C/N ratio may reflect enhanced preservation of organic material as a result of the rapid sweepout and burial of plankton by impact ejecta, with little or no bacterial degradation. It is conceivable that the shift in delta value of N-15 may represent an influx of nitrogen from a different source deposited contemporaneously with the impact ejecta. An interesting possibility is that it may be derived from nitrate, produced from the combustion of atmospheric nitrogen

LASIG II - Pulsed laser ion generator study Final report

Ion current produced by illuminating materials with focused output of pulsed ruby lase

The fluorine-NHC gauche effect: a structural and computational study

Herein, we report the synthesis and X-ray structural analysis of a collection of fluorinated metal N-heterocyclic carbenes (Ag, Au, Pd, Rh, Ir) and their precursor salts. The common structural feature of these species is a flanking fluoroethyl group which is either freely rotating or embedded within a bicyclic framework. Solid state analysis confirmed a gauche conformational preference in all cases with the fluorine adopting a syn clinal arrangement (ϕ[NCCF] ~ 60°) with respect to the triazolium nitrogen at the vicinal position of the NHC. A density functional theory analysis was employed to quantify these effects and evaluate the influence of electronic modulation of the carbenic carbon [(C=N+); neutral carbene (C:); metal-bound carbene (C=M)], on the relative gauche / anti preference, thus highlighting the potential of this conformational phenomenon as a useful molecular design strategy for controlling the topology of organometallic complexes

Can acyclic conformational control be achieved via a sulfur-fluorine gauche effect?

The gauche conformation of the 1,2-difluoroethane motif is known to involve stabilising hyperconjugative interactions between donor (bonding, σC-H) and acceptor (antibonding, σ*C-F) orbitals. This model rationalises the generic conformational preference of F-Cβ-Cα-X systems (φFCCX ≈ 60°), where X is an electron deficient substituent containing a Period 2 atom. Little is known about the corresponding Period 3 systems, such as sulfur and phosphorus, where multiple oxidation states are possible. Conformational analyses of β-fluorosulfides, -sulfoxides and -sulfones are disclosed here, thus extending the scope of the fluorine gauche effect to the 3rd Period (F-C-C-S(O) n ; φFCCS ≈ 60°). Synergy between experiment and computation has revealed that the gauche effect is only pronounced in structures bearing an electropositive vicinal sulfur atom (S+-O-, SO2)

The authority of the United Nations to 'intervene' within the meaning of Article 2(7) of the Charter

No subject within the discipline of Public International Law is more topical at the present time than that of intervention. The war in Viet-Nam and the American action in the Dominican Republic have, once again, brought this most controversial subject to the fore. These are, however, examples of unilateral intervention and it is not the purpose of this study to elaborate the principles of law, if any, which apply to them. The present purpose is to study certain aspects of the law of intervention under the Charter of the United Nations, itself a topic which engenders a lot of feeling and which has been the subject of controversy ever since the inception of the Organization.The present study is timely, the United Nations itself at last having turned its thoughts to the study of this question. It is hoped that the following study may shed some light on the practice which has ensued in the organs of the United Nations and the trends which have developed therein in this regard

Water Treatment Using Advanced Oxidation Processes: Application Perspectives

Advanced oxidation processes (AOPs) using hydroxyl radicals and other oxidative radical species are being studied extensively for removal of organic compounds from various waste streams. However, large scale applications of these highly effective technologies in water and wastewater treatment are still very limited due to cost and inadequate information about the resultant water quality. This study focuses on the evaluation of the upstream processing and downstream post treatment analysis of selective AOPs. In the first stage of research, the performance of a proprietary catalyst (VN-TiO2) was compared with the industry standard P25 TiO2, for the use in a pilot-scale immobilized photocatalytic reactor. Using a dip coated fibreglass disk support in the VN-TiO2 solution and calcining, porous films with high surface area were produced. Although films formed by VN-TiO2 on fibreglass disks had a reaction rate 50% lower than that of P25, the VN-TiO2 disks were mechanically robust in the reactor, compared to those coated with P25. The addition of 15% P25 in the VN-TiO2 solution increased the reaction rate by 40%, while maintaining the mechanical stability. Reuse potential of both catalysts (VN-TiO2 and P25) was tested, and the rates of deactivation were comparable for both catalysts. Deactivation occurred possibly due to sustained adsorption of intermediates as well as loss of active sites due to heat treatment for reactivation. The low cost of the fibreglass, as compared to commonly used borosilicate glass, in combination with the VN-TiO2 catalyst is ideal for testing pilot scale reactor designs. In the second stage of the study two bioassays were used to evaluate and compare the toxicity of bisphenol A, and its degradation intermediates formed in three AOPs, namely UV/H2O2, ozonation, and photocatalysis. Two assays were used in evaluating water quality, namely the Ames Test for mutagenicity and the YES assay for estrogencity. Both UV/H2O2 and ozonation removed less than 10% of the initial total organic carbon (TOC), whereas photocatalysis resulted in a 50% reduction of TOC indicating a significant difference in intermediate formation. No mutagenicity was found over the entire tested range of BPA degradation in any of the AOPs. Estrogenicity steadily decreased in accordance with BPA degradation, and was below the limit of detection for photocatalysis. UV/H2O2 and ozonation results indicated the possible formation of intermediates with slight estrogenic activity as estrogenicity reached a plateau with a constant value at 15% of initial estrogenicity, while BPA continued to degrade with time. The work demonstrated effective use of bioassay tools in determining performances of AOPs

The combustion characteristics and stable carbon isotopic compositions of irradiated organic matter: implications for terrestrial and extraterrestrial sample analysis

Exposure to ionizing radiation causes the mean combustion temperature of naturally occurring, solid, terrestrial organic matter, derived from the radiation-induced polymerization of methane, to increase

Synthesis and First Hyperpolarizabilities of Acceptor-substituted β-apo-8’-Carotenal Derived Compounds

The synthesis and second-order nonlinear optical properties of acceptor-substituted biologically derived β-apo-8′-carotenal compounds are reported; electric field-induced second harmonic generation (EFISH) measurements give values of β(0) which are 2–6 times greater than for 4-N,N-dimethylamino-4′-nitrostilbene (DANS)