Photodissociation and quantum yield determination of peroxyacetyl nitrate

Thesis (M.S.) University of Alaska Fairbanks, 2003Peroxyacetyl nitrate (PAN) is an important atmospheric species due to its role in global transport of reactive nitrogen oxides, NOx (= ·NO₂ + ·NO). Peroxyacetyl nitrate is formed by reactions involving hydrocarbons and ·NO₂ in polluted regions and can be transported into the Arctic. To understand the role of PAN as a transporter of NOx to the Arctic, we need to quantify its decomposition pathways which include: thermal decomposition, photolysis, and reaction with the hydroxyl radical (·OH). In colder regions, such as the Arctic, the most rapid decomposition pathway is photolysis. Several photolytic pathways are possible for PAN. We photolyzed PAN in the laboratory using a frequency-doubled tunable dye laser. A highly sensitive technique called cavity ring-down spectroscopy (CRDS) probed the ·NO₃ produced in the photolysis reaction and we quantified the quantum yield for production of ·NO₃. The quantum yield is the fraction of photoexcited molecules that decompose to a certain chemical product. We determined that the quantum yield of ·NO₃ at 289 nm is 0.30 [plus/minus] 0.08. These results are discussed in context of previous work on PAN photolysis and in terms of a mechanistic model.Ch. 1. Atmospheric chemistry of peroxyacetyl nitrate -- ch. 2. Synthesis and photochemical properties of PAN and N₂O₅ -- ch. 3. Experimental and system design -- ch. 4. Calculations -- ch. 5. Results -- ch. 6. Discussion and conclusion -- References

Collaborative supply chain modelling and performance measurement

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 11/12/2002.For many years, supply chain research focused on operational aspects and therefore mainly on the optimisation of parts of the production and distribution processes. Recently, there has been an increasing interest in supply chain management and collaboration between supply chain partners. However, there is no model that takes into consideration all aspects required to adequately represent and measure the performance of a collaborative supply chain. This thesis proposes a model of a collaborative supply chain, consisting of six constituents, all of which are required in order to provide a complete picture of such a collaborative supply chain. In conjunction with that, a collaborative supply chain performance indicator is developed. It is based on three types of measures to allow the adequate measurement of collaborative supply chain performance. The proposed model of a collaborative supply chain and the collaborative supply chain performance indicator are implemented as a computer simulation. This is done in the form of a decision support environment, whose purpose is to show how changes in any of the six constituents affect collaborative supply chain performance. The decision support environment is configured and populated with information and data obtained in a case study. Verification and validation testing in three different scenarios demonstrate that the decision support environment adequately fulfils it purpose

A Biological Review of Mental Illness: An Overview of Genetics and Pathophysiology of Schizophrenia, Major Depression, and Addiction

Novel approaches in understanding mental illness present solutions to current issues in treatment and diagnosis. With advancements in genetics and neurology, the etiology and pathophysiology of mental illness is slowly unwrapping. In discovering biomarkers for depression, addiction, and schizophrenia, the precision for preventing, diagnosing, and treating these disorders increases. The aim of this paper is to review current research for addiction, major depression, and schizophrenia in genetics and physiology, while also clarifying the need for reclassifying mental illness as diseases with a pathophysiological basis, not syndromal, idiopathic disorders. Mental illness is dynamic in that it encompasses both environmental and biological factors, but research emphasis on the latter has potential to improve the treatment of disorders, and possibly prevent them

Spectral diffusion and 14N quadrupole splittings in absorption detected magnetic resonance hole burning spectra of photosynthetic reaction centers

Zero field absorption detected magnetic resonance hole burning measurements were performed on photosynthetic reaction centers of the bacteria Rhodobacter sphaeroides R26 and Rhodopseudomonas viridis. Extrapolation to zero microwave power yielded pseudohomogeneous linewidths of 2.0 MHz for Rhodopseudomonas viridis, 1.0 and 0.9 MHz for the protonated forms of Rhodobacter sphaeroides R26 with and without monomer bacteriochlorophyll exchanged, and 0.25 MHz as an upper limit for fully deuterated reaction centers of Rhodobacter sphaeroides R26. The measured linewidths were interpreted as being due to unresolved hyperfine interaction between the nuclear spins and the triplet electron spin, the line shape being determined by spectral diffusion among the nuclei. The difference in linewidths between Rhodobacter sphaeroides R26 and Rhodopseudomonas viridis is then explained by triplet delocalization on the special pair in the former, and localization on one dimer half on the latter. In the fully deuterated sample, four quadrupole satellites were observed in the hole spectra arising from the eight 14N nitrogens in the special pair. The quadrupole parameters seem to be very similar for all nitrogens and were determined to =1.25±0.1 MHz and =0.9±0.1 MHz. The Journal of Chemical Physics is copyrighted by The American Institute of Physics

CHEMICALLY MODIFIED PHOTOSYNTHETIC BACTERIAL REACTION CENTERS: CIRCULAR DICHROISM, RAMAN RESONANCE, LOW TEMPERATURE ABSORPTION, FLUORESCENCE AND ODMR SPECTRA AND POLYPEPTIDE COMPOSITION OF BOROHYDRIDE TREATED REACTION CENTERS FROM Rhodobacter sphaeroides R26

Reaction centers from Rhodobacter sphaeroides have been modified by treatment with sodium borohydride similar to the original procedure [Ditson et al., Biochim. Biophys. Acta 766, 623 (1984)], and investigated spectroscopically and by gel electrophoresis. (1) Low temperature (1.2 K) absorption, fluorescence, absorption- and fluorescence-detected ODMR, and microwave-induced singlet-triplet absorption difference spectra (MIA) suggest that the treatment produces a spectroscopically homogeneous preparation with one of the ‘additional’ bacteriochlorophylls being removed. The modification does not alter the zero field splitting parameters of the primary donor triplet (TP870). (2) From the circular dichroism and Raman resonance spectra in the1500–1800 cm-1 region, the removed pigment is assigned to BchlM, e.g. the "extra" Bchl on the "inactive" M-branch. (3) A strong coupling among all pigment molecules is deduced from the circular dichroism spectra, because pronounced band-shifts and/or intensity changes occur in the spectral components assigned to all pigments. This is supported by distinct differences among the MIA spectra of untreated and modified reaction centers, as well as by Raman resonance. (4) The modification is accompanied by partial proteolytic cleavage of the M-subunit. The preparation is thus spectroscopically homogeneous, but biochemically heterogenous

Monopoly and Monopsony: Antitrust Standing, Injury, and Damages

This article examines the economic consequences of collusion in both the output market and one of the input markets. It examines the results of sequential collusion, which leads to complications and inconsistencies in measuring antitrust damages. It also examines simultaneous collusion in both the input and output markets. Ultimately, the profit maximizing equilibrium is identical but there are complications along the way to the final collusive equilibrium. The article explores the private plaintiff problems involving antitrust standing, proving antitrust injury, and estimating antitrust damages

ESR Study of (C_5H_{12}N)_2CuBr_4

ESR studies at 9.27, 95.4, and 289.7 GHz have been performed on (C$_5$H$_{12}$N)$_2$CuBr$_4$ down to 3.7 K. The 9.27 GHz data were acquired with a single crystal and do not indicate the presence of any structural transitions. The high frequency data were collected with a polycrystalline sample and resolved two absorbances, consistent with two crystallographic orientations of the magnetic sites and with earlier ESR studies performed at 300 K. Below $B_{C1}=6.6$ T, our data confirm the presence of a spin singlet ground state.Comment: 2 pages, 4 figs., submitted 23rd International Conference on Low Temperature Physics (LT-23), Aug. 200