Tesis sobre el tema "Collector of Excise"

We create fictions--personal and literary--to cope with fear, and it is our choice whether or not these inventions affirm life. This collection presents many ways of "making excuses for the universe," both from a personal standpoint and also by using the voices and visions of created characters. The collection contains a section of family poems and three sets of character poems: Beverly and Nanci, Strange Mary, and Blue Donna. Following each section are two related poems for transition or amplification. The poems show a progressive change in writing techniques, especially experimentation with sound, as well as pursuing the central theme that perception is a desirable goal, well worth the price.

Chemistry
Ph.D.
As one of the simplest tri-atomic molecules, SO2 is extremely important in various fields in chemistry. SO2 is released by volcanoes and various industrial processes including combustion of sulfur containing fuel, and is well known to be the key chemical that causes the acid rain on earth. Therefore, SO2 has been studied intensively in both atmospheric chemistry as well as combustion chemistry. SO2 has also been discovered in extraterrestrial environment. For example, it is reported to be the most abundant gas observed in the atmosphere of Jupiter's moon, Io[1]. It has therefore generated great interests in the planetary chemistry as well. Even though understanding the structure, spectroscopy and reaction dynamics of SO2 has been of great and fundamental interests for more than 50 years, there are yet some very interesting topics, particularly those related to highly excited SO2, that require further investigations. In this thesis, we combine time-resolved Fourier transform infrared emission spectroscopy with theoretical modeling to study selected interesting problems relevant to highly excited SO2. First, the photodissociation of SO2 molecule by 193 nm photons is investigated. The role of different predissociation channels of electronically excited SO2 is carefully defined. Secondly, the excitation of SO2 by hot H atoms, a topic important in combustion and atmospheric chemistry, is examined. The energy transfer mechanism is identified and discussed. This newly discovered energy transfer mechanism involves the formation of the reactive intermediate species, which will greatly enhance the energy transfer efficiency on top of the classical impulsive type of collision mechanisms. In addition, the collision quenching of highly vibrationally excited SO2 with about 32,000 cm-1 energy is studied. It is found that the long range interactions contribute significantly to vibration to vibration (V-V) energy transfer. The contributions from both long range and impulsive mechanisms are discussed in detail. The studies presented in this thesis have provided important insight on the collision energy transfer and reaction dynamics of highly excited SO2 that would be useful in assessing the behavior of this important molecule in atmospheric, planetary, and combustive environments.
Temple University--Theses

Cardiovascular disease, including hypertension, accounts for almost 50% of the deaths in patients with end stage renal disease (ESRD) on hemodialysis (HD) yet hypertension remains very poorly controlled in this population. The purpose of this study was to retrospectively compare control of hypertension in hemodialysis (HD) patients when extracellular volume (ECV) was assessed and managed by clinical parameters and physical assessment data alone with control of hypertension when data from blood volume monitoring (BVM) technology was also used to assess and manage ECV in a freestanding outpatient hemodialysis unit. The main cause of hypertension in the ESRD population has been identified as increased ECV most likely secondary to increased interdialytic weight gain and failure to attain and maintain patient's dry weight. HD nurses often employ clinical parameters along with physical examination to determine a patient's pre, intra, and post dialytic fluid status and this approach can have a high index of error. BVM technology is being used in many hemodialysis units to assist with assessment of ECV. A comparative retrospective chart review was used to collect data for this project. A descriptive, cross-sectional design was employed to answer the question: "Are hypertensive hemodialysis patients who dialyze in a freestanding dialysis unit, where BVM technology is utilized, more likely to be normotensive as defined by a pre dialysis blood pressure of less than 140/90 and post dialysis blood pressure less than 130/80"? A pilot study was conducted to determine if the patient population and data were available in existing patient records for extrapolation. Approval for the study was obtained from the University IRB. A convenience sample was obtained from the records of patients meeting the inclusion criteria.; Variables were measured and analyzed using descriptive statistics such as sampled paired T-test to compare pre and post BVM systolic, diastolic blood pressures, intradialytic weight gain, serum Albumin and sodium levels, and hemoglobin. A p-value of 0.05 was assigned for statistical significance. Data analysis showed there were statisticaly significant differences in the pre dialysis systolic blood pressure, post BVM, and the serum sodium pre and post BVM when the two groups were compared These statistically significant findings support a correlation between reduction in the HD patient's ECV and improved blood pressure control. The reduction of pre-dialysis SBP was significant because many patients on hemodialysis have systolic hypertension that may or may not coexist with diastolic hypertension. The findings of this study may be used to formulate a protocol to be used in the HD units where the BVM is available. The protocol would rely on accurate nursing assessment of clinical parameters, patient verbalizations of symptoms, and the routine use of the BVM in order to continuously assess the patient's fluid status. Future research recommendations include conducting the study in a population closer to the national sample, a study where glucose readings and /or hemoglobin A1C levels are measured to assess the impact of glucose on ECV, and which antihypertensive class of medication works best with BVM technology to effectively manage hypertension in this population.
ID: 029808737; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (D.N.P.)--University of Central Florida, 2011.; Includes bibliographical references (p. 74-81).
D.N.P.
Doctorate
Nursing
Nursing Practice

This dissertation consists of three essays on the effect of excess compensation and corporate governance changes on the firm's performance. The first paper utilizes a cost minimization stochastic frontier approach to investigate the efficiency of director total compensation. Our findings suggest that board members are over compensated. We show that, on average, the director actual compensation level is above the efficient compensation level by around 63%. Our results suggest that an increase in director excess compensation decreases the likelihood of CEO turnover, reduces the turnover-performance sensitivity, and increases managerial entrenchment. Thus, the surplus in director compensation is directly associated with managerial job security and entrenchment. Furthermore, although director excess compensation is not significantly inversely related to the firm's future performance, it has an indirect negative effect on future performance through its impact on the entrenchment-performance relationship. Therefore, this essay proposes that the overcompensation of directors is directly associated with a board culture predicated by mutual back-scratching and collusion between the CEO and the board members. The second essay tests the effect of an exogenous shock, the Sarbanes-Oxley Act (SOX) of 2002, on the structure of corporate boards and their efficiency as a monitoring mechanism. The results suggest an increase in the participation of independent directors at the expense of insiders. Consequently, we investigate the implications of board composition changes on CEO turnover and firm value. We document a noticeable reduction in CEO turnover in the post-SOX period. We also demonstrate that, after SOX, a board dominated by independent directors is less likely to remove a CEO due to poor performance. Finally, we highlight a negative association between the change in board composition and firm value. We propose that our findings are predicated on an off equilibrium result whereby firms were forced to modify their endogenously chosen board composition. Therefore, contrary to the legislators' objectives, we suggest that the change in board structure brought about inefficient monitoring and promoted an unfavorable tradeoff between independent directors and insiders. The third essay examines the relationship between the firm's governance structure and its value during different economic conditions. We show that both relative industry turnover and CEO entrenchment increase during economic downturns. We also find that relative industry turnover and managerial entrenchment have opposite impacts on the value of the firm throughout the recessionary period. While industry turnover leads to an appreciation in firm value, managerial entrenchment reduces shareholders' wealth. The negative impact of managerial entrenchment on firm value, however, outweighs the positive impact of industry turnover. Accordingly, we propose that a recession provides managers with a good opportunity to camouflage their behavior and extract more private benefits and, thus, blame the poor performance on bad economic conditions.
ID: 031001341; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Title from PDF title page (viewed April 15, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references.
Ph.D.
Doctorate
Business Administration
Business Administration; Finance

Chemistry
Ph.D.
The excited state electronic structures of several biologically important chromophores were studied by Stark spectroscopy. The extent of charge redistribution upon excitation to the lowest excited states of the oxidized and semiquinone forms of flavin adenine dinucleotide (FAD) bound to the light activated DNA repair enzyme DNA photolyase have been studied previously by this technique. This work focuses on the catalytically active form, the two-electron reduced anion. To facilitate analysis of this experiment, the Stark spectra of a simple flavin derivative that is soluble in organic solvents was measured. The results of the analysis of these data are in agreement with previously a published linear dichroism experiment that found the absorption spectrum of flavins in this redox state arises from two distinct electonic transitions in the visible/near-ultraviolet spectral range, a fact that has not been incorporated into the analysis of many ultrafast spectroscopic experiments of reduced anionic flavins/flavoproteins. The difference dipole moment of the second, more intense, transition was found to be about twice as large as that of the lowest energy transition. With the aid of ab initio calculations, the directions of these dipole moments in the molecular frame were assigned. For both transitions, it was found that negative charge density is shifted toward the xylene ring of the flavin upon excitation. Another important consideration for the correct analysis of the photolyase spectra is the possibility of contamination by small amounts of the antenna chromophore, which also has absorption intensity in the near-ultraviolet region. We chose to study the cofactor for E. coli photolyase, 5,10-methenyltetrahydrofolate, and its photodecomposition product, 5,10-methylenetetrahydrofolate. The difference dipole moments for the lowest energy transitions of both of these chromophores were found to be quite large, ranging from 9-12 D fc and lying primarily along the transition dipole moment. Additionally, the difference polarizability of both chromophores was large, on the order of 200-300 Å3 fc2 . The Stark spectra of reduced anionic FAD in photolyase agrees well with the findings of the experiments on flavin in organic solvent; the magnitude of the difference dipole moments in both cases match within experimental error. While the direction of the difference dipole moment for the lowest transition is also the same in both cases, that of the second transition is changed in the protein matrix. The assignment of these vectors in the molecular frame shows that the two dipole moments are coincident for the cofactor bound to photolyase. This finding, where electron density is shifted toward the point of the flavin ring closes to the DNA lesion bound to the enzyme, is strong evidence that direct electron transfer takes place from the isoalloxazine ring of FAD to the DNA substrate in the catalytic cycle. The usefulness of Stark spectroscopy in investigating photoinduced charge redistribution was also shown for the donor-π-acceptor flavin dyad, azobenzylflavin (ABFL). The difference dipole moment was found to be 22 D, an approximately three-fold increase from the largest difference dipole moment found in naturally occurring flavins. This extensive charge redistribution corresponds to a large hyperpolarizability of the chromophore that suggests that ABFL may be useful in nonlinear optical applications. Transient absorption was used to supplement these experiments by monitoring the decay kinetics of ABFL after excitation. It was found that ABFL undergoes ultrafast charge recombination within 6 ps after excitation, leading to depopulation of the charge separated state before useful work can be performed for applications requiring electron transfer. These studies provide the ground work for rational design of other ABFL-like derivatives for use in a variety of applications.
Temple University--Theses

Chemistry
Ph.D.
Repair mechanisms for damaged DNA are essential for the proliferation of nearly all forms of life. Although DNA is quite robust, the vital information-storing molecule can often be damaged from environmental exposures such as ultra-violet (UV) light. Exposure to UV light can result in various types of mutagens creating structural damages. One specific type of UV-induced damage is the creation of a cyclobutylpyrimidine dimer (CPD). This specific type of lesion can be efficiently repaired by the flavoenzyme DNA photolyase (PL). DNA photolyase is an ancient protein found across kingdoms and plays a crucial role in preventing mutagenesis and cell death. DNA photolyase is a monomeric flavoprotein that utilizes blue light to repair UV-induced CPD lesions in DNA via an electron transfer mechanism. All photolyases contain at least one flavin adenine dinucleotide (FAD) molecule as the catalytic cofactor responsible for initiating the electron transfer induced repair process. Flavin cofactors are intriguing because of their unique ability to donate one or two electrons. The conservation of FAD and the unique U-shaped configuration of FAD in PL led researchers to question if the adenine moiety of the FAD molecule was essential in the DNA repair mechanism and generated a spectral signature indicative of a radical adenine species. The importance of the adenine moiety could be linked to structural changes associated with environmental temperature. The rate of electron transfer is exponentially dependent on temperature and DNA photolyase is found in organisms which thrive in harsh environments that vary in temperature, pH, ionic strength etc. Photolyase presents a unique opportunity to study the adaptations that are required for proteins to function in extreme environments where temperature dependent processes should show dramatic differences. We have used ultrafast transient absorption spectroscopy to compare the similarities and differences in excited state dynamics of the FAD cofactor. Photolyase isolated from the hyperthermophilic archaea Sulfolobus solfataricus (SsPL) is compared to PL isolated from the mesophilic E. coli (EcPL). These results indicate differences in the dynamics of fully reduced flavin between enzymes as a function of temperature. We present evidence for charge separation in the FAD cofactor in the thermophilic enzyme previously seen in computation studies of photolyase. To investigate the excited state charge redistribution of flavin which is critical to its role in nature, the charge redistribution of the precursors to flavin biosynthesis were examined. Lumazine is a precursor in the biosynthetic pathway of flavins. As such, lumazine could have served as an enzymatic cofactor prior to flavins. Lumazine has been identified in biological processes, however it is not as prevalent as flavins. We utilize Stark spectroscopy to examine the charge redistribution in excited state lumazine to understand
Temple University--Theses

Recent, cooperative advances in chemistry, biology, computing, photophysics, optics, and microelectronics have resulted in extraordinary developments in the biological sciences, resulting in the emergence of a novel area termed 'biophotonics'. The integrative and interdisciplinary nature of biophotonics cuts across virtually all disciplines, extending the frontiers of basic cellular, molecular, and biology research through the clinical and pharmaceutical industries. This holds true for the development and application of the novel imaging modality utilizing multiphoton absorption and its extraordinary contribution to recent advances in bioimaging. Intimately involved in the revolution of nonlinear bioimaging has been the development of optical probes for probing biological function and activity. The focus of this dissertation is in the area of probe development, particularly conjugated organic probes, optimized for efficient two-photon absorption followed by upconverted fluorescence for nonlinear, multiphoton bioimaging applications. Specifically, [pi]-conjugated fluorene molecules, with enhanced two-photon absorbing (2PA) properties and high photostability, were prepared and characterized. Contemporary synthetic methods were utilized to prepare target fluorene derivatives expected to be highly fluorescent for fluorescence imaging, and, in particular, exhibit high two-photon absorptivity suitable for two-photon excitation (2PE) fluorescence microscopy. The flexibility afforded through synthetic manipulation to integrate hydrophilic moieties into the fluorophore architecture to enhance compatibility with aqueous systems, more native to biological samples, was attempted. Incorporation of functional groups for direct covalent attachment onto target biomolecules was also pursued to prepare fluorene derivatives as efficient 2PA reactive probes. Linear and two-photon spectroscopic characterizations on these novel compounds reveal they exhibit high 2PA cross-sections on the order of ~100 GM units, nearly an order of magnitude greater than typical, commonly used fluorophores utilized in nonlinear, multiphoton microscopy imaging of biological samples. Photostability studies of representative fluorene derivatives investigated and quantified indicate these derivatives are photostable under one- and two-photon excitation conditions, with photodecomposition quantum yields on the order of 10[super-5]. Preliminary cytotoxicity studies indicate these fluorene derivatives exhibit minimal cytotoxic effects on proliferating cells. Finally, their ultimate utility as high-performance, 2PA fluorescent probes in 2PE fluorescence microscopy imaging of biological samples was demonstrated in both fixed and live cells. Due to the low cytotoxicity, high photostability, efficient 2PA, and high fluorescence quantum yield, the probes were found suitable for relatively long-term, two-photon fluorescence imaging of live cells, representing a significant advance in biophotonics.
Ph.D.
Department of Chemistry
Arts and Sciences
Biomolecular Sciences: Ph.D.

Polycyclic aromatic compounds (PACs), which comprise a complex class of condensed multi-ring benzenoid compounds, are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. PACs are generally formed during incomplete combustion of pyrolisis of organic matter containing carbon and hydrogen. Because combustion of organic materials is involved in countless natural processes or human activities, PACs are omnipresent and abundant pollutants in air, soil, and water. Chemical analysis of PACs is of great environmental and toxicological importance. Many of them are highly suspect as etiological agents in human cancer. Because PACs carcinogenic properties strongly depend on molecular structure and differ significantly from isomer to isomer, it is of paramount importance to determine the most toxic isomers even if they are present at much lower concentrations than their less toxic isomers. Gas chromatography (GC), high-resolution GC, and high-performance liquid chromatography (HPLC) are the basis for standard PACs identification and determination. Many cases exist where GC, HPLC, and even HR-GC have not been capable to provide unambiguous isomer identification. The lack of reliable analytical data has lead to serious errors in environmental and toxicological studies. This dissertation deals with the development of novel instrumentation and analytical methods for the analysis of PACs in environmental samples. The developed methodology is based on two well-known high-resolution luminescence techniques, namely Shpol'skii Spectroscopy (SS) and Fluorescence Line Narrowing Spectroscopy (FLNS). Although these two techniques have long been recognized for their capability in providing direct determination of target PACs in complex environmental samples, several reasons have hampered their widespread use for the problem at hand. These include inconvenient sample freezing procedures; questions about signal reproducibility; lengthy spectral acquisition, which might cause severe sample degradation due to prolonged excitation; broadband fluorescence background that degrades quality of spectra, precision of measurements and detection limits; solvent constrains imposed by the need of optically transparent media; and, most importantly, the lack of selectivity and sensitivity for unambiguous determination of closely related PACs metabolites. This dissertation presents significant advances on all fronts. The analytical methodology is then extended to the analysis of fluoroquinolones (FQs) in aqueous samples. FQs are one of the most powerful classes of antibiotics currently used for the treatment of urinary tract infections. Their widespread use in both human and animal medicine has prompted their appearance in aquatic systems. The search for a universal method capable to face this new environmental challenge has been centered on HPLC. Depending on the FQ and its concentration level, successful determination has been accomplished with mass spectrometry, room-temperature fluorescence (RTF) or UV absorption spectrometry. Unfortunately, no single detection mode has shown the ability to detect all FQ at the concentration ratios found in environmental waters. We provide a feasible alternative based on FLNS. On the instrumentation side, we present a single instrument with the capability to collect multidimensional data formats in both the fluorescence and the phosphorescence time domains. We demonstrate the ability to perform luminescence measurements in highly scattering media by comparing the precision of measurements in optically transparent solvents (Shpol'skii solvents) to those obtained in "snow-like" matrixes and solid samples. For decades, conventional low-temperature methodology has been restricted to optically transparent media. This restriction has limited its application to organic solvents that freeze into a glass. In this dissertation, we remove this limitation with the use of cryogenic fiber-optic probes. Our final efforts deal with low-temperature absorption measurements. Recording absorption spectra via transmittance through frozen matrixes is a challenging task. The main reason is the difficulty to overcome the strong scattering light reaching the detector. This is particularly true when thick samples are necessary for recording absorption spectra of weak oscillators. In the case of strongly fluorescent compounds, additional errors in absorbance measurements arise from the emission reaching the detector, which might have comparable intensity to that of the transmitted light. We present a fundamentally different approach to low-temperature absorption measurements as the sought-for-information is the intensity of laser excitation returning from the frozen sample to the intensified-charge coupled device (ICCD). Laser excitation is collected with the aid of a cryogenic fiber optic probe. The feasibility of our approach is demonstrated with single-site and multiple-site Shpol'skii systems. 4.2K absorption spectra show excellent agreement to their literature counterparts recorded via transmittance with closed cycle cryogenators. Fluorescence quantum yields measured at room-temperature compare well to experimental data acquired in our lab via classical methodology. Similar agreement is observed between 77K fluorescence quantum yields and previously reported data acquired with classical methodology. We then extend our approach to generate original data on fluorescence quantum yields at 4.2K.
Ph.D.
Department of Chemistry
Sciences
Chemistry: Ph.D.

Chemistry
Ph.D.
An overexposure to ultraviolet radiation can cause sunburn and some forms of skin cancer. UV light causes many different photoproducts. The cys-syn cyclobutylpyrimidine dimer (CPD) is the major photoproduct upon UV irradiation. DNA photolyase (PL) is a light-driven flavoprotein that repairs CPD in UV-damaged DNA. This repair process occurs in the presence of blue light through ultrafast photo-induced electron transfer from reduced anionic flavin adenine dinucleotide (FADH¯) to the CPD by an unknown mechanism. Since the excited state flavin transfers an electron to repair the damaged DNA, it is of utmost importance that we understand better the excited state properties of the flavins. In this work the excited state electronic properties of all three-oxidation states of flavin: oxidized form (FAD), semiquinone radical form (FADH•) and reduced anionic form (FADH¯) were studied using Stark spectroscopy and complimented by time dependent density functional theory (TD-DFT) calculations. These results are presented and discussed in Chapter 3 and 4. The difference dipole moments (Δμ) and the difference polarizabilities (Tr(Δα01)) were experimentally determined for first two lowest optically accessible states. The results are discussed in the context of photoreduction of flavins in wider class of flavoprotein blue light photoreceptors and catalytic electron transfer process in DNA repair. In the later part of this thesis (Chapters 5 and 6) the excited state electronic properties of monomeric 2-Aminopurine (2AP), 8-Vinyladenine 8VA were presented. These 8VA, 2AP are examples of fluorescent nucleotide analogues of adenine that can be incorporated into DNA with little perturbation of the normal double-helical structure. The fluorescence of these analogues is quenched when incorporated in double-stranded DNA (dsDNA). The basic mechanism underlying the fluorescence quenching by base stacking of 2AP and 8VA are is not well understood, and thus exploring the excited state electronic structures of these bases is an important first step. We have explored the excited state properties of 2AP and 8VA in frozen LiCl and ethanol solutions using Stark spectroscopy. High-level ab initio and TD-DFT calculations were performed to compliment the experimental results.
Temple University--Theses

Une methode combinatoire pour le calcul des densites de niveaux particules-trous et totales est presentee dans le cadre du modele general a particules independantes. Les modes collectifs de rotation et de vibration peuvent etre pris en compte ou ignores, ce qui respectivement conduit aux notions de densites effectives et intrinseques. On applique tout d'abord notre approche dans le cas ou les niveaux individuels du modele sont equidistants. Une nouvelle formule analytique pour les densites de niveaux particules-trous intrinseques est alors etablie. Cette expression fournit des resultats en parfait accord avec nos calculs combinatoires et constitue une generalisation de nombreuses relations proposees dans la litterature. Notre methode est ensuite employee avec des niveaux individuels deduits de calculs microscopiques fondes sur la theorie hartree-fock-bogoliubov utilisant la force effective nucleon-nucleon d1s de gogny. On montre ainsi que la prise en compte des effets collectifs conduit a un accord satisfaisant entre nos predictions et les donnees experimentales disponibles pour les espacements moyens des resonances s a l'energie de liaison du neutron. La validite de la formule d'ignatyuk pour decrire la variation du parametre de densite de niveaux avec l'energie d'excitation est aussi discutee. Le role et la maniere de prendre en compte les effets collectifs dans le calcul des densites de niveaux totales sont egalement etudies. On explique ainsi la diminution du parametre de densite de niveaux a haute energie comme la consequence de l'extinction progressive des effets collectifs.

Chemistry
Ph.D.
The development of quantum mechanics has historically allowed researchers to theoretically explore the fundamental physical properties of atoms and molecules. Although quantum mechanics has been around for almost a century, its use was largely limited by the computational complexity it demanded. In the past decade, computer technology has evolved to the point where it is possible to perform calculations on biologically relevant systems. This has allowed us to corroborate results obtained from experiment as well as predict and explain phenomena that experiment cannot. Unfortunately, the field as a whole has not progressed to the point where high level methods, such as Multi-Reference Configuration Interaction (MRCI), are applicable to large molecular systems. Thus, to effectively study these systems, compromises must be made. In this work, two different approaches are taken to study the photophysical properties of systems such as DNA. In the first approach, a model system is formulated and studied in lieu of the larger target system. The excited state dynamics of 8-oxoguanine (8-oG) and its anion are studied in order to assess the possibility of taking part in an electron transfer mechanism to repair a nearby cyclobutane pyrimidine dimer (CPD). It is found that barriers on the anion S1 excited state surface prohibits easy access to conical intersections with the ground state, causing the anion to have a much longer excited state lifetime than the neutral form. Although much insight can be gained by this method, it is not uncommon for crucial interactions to be lost through simplification. In this case, when 8-oG is placed in an adenine dinucleotide, the π stacking interaction allows it to form a long lived radical base pair, which may be fundamental to its role in CPD repair. Unfortunately, it is impossible to carry out the same excited state calculations for the 8-oG/adenine dinucleotide due to computational cost. For reasons such as these, we also implement and benchmark a new approach to carrying out high level configuration interaction calculations in which the MRCI is expanded in the basis of high multiplicity natural orbitals (HMNOs). Specifically, the HMNO approach is implemented by expanding the MRCI wavefunction in the basis of natural orbitals generated from a ground state high multiplicity Configuration Interaction Singles and Doubles (CISD) calculation. Excited state calculations both at and away from the Franck-Condon region were performed to benchmark the ability of the HMNO approach using CISD and MRCI to reproduce standard MRCI energies. The ability of the HMNOs to be truncated was also explored, yielding efficient truncation criteria and guidelines for choosing the best basis set. It is found that the MRCI/HMNO approach yields energies that are in excellent agreement with standard MRCI while only requiring a fraction of the computational effort, possibly allowing it to be applied to larger systems such as nucleotide dimers.
Temple University--Theses

The goal of this research is to test the design constraints of active dpp-bridged RuII,RhIII (dpp = 2,3-bis(2-pyridyl)pyrazine)) supramolecular photocatalysts for water reduction to H2 and provide mechanistic insights into the catalytic cycle. Two member of a new RuII,RhIII motifs with only one Rh-'Cl bond, [(bpy)2Ru(dpp)RhCl(tpy)](PF6)4 ( bpy = 2,2'-bipyridine, tpy = 2,2':6,2"-terpyridine) and [(bpy)2Ru(dpp)RhCl(tpm)](PF6)4, (tpm = tris(1-pyrazolyl)methane), and a cis-RhCl2 model system, [(bpy)2Ru(dpp)RhCl2(bpy)](PF6)3, were prepared. This new motif was to test whether two Rh-'Cl bonds on RhIII are required for the photocatalytic water reduction. 1H NMR spectroscopic analysis of complexes prepared using deuterated ligands was used to characterize these three RuII,RhIII supramolecular complexes. Electrochemical studies suggested that replacing bpy with a tridentate ligand on RhIII shifts the RhIII/II and RhII/I reduction couples positively, which can modulate the orbital energetics of the RhIII LUMO (lowest-unoccupied molecular orbital). This substitute also changes the rate of ligand dissociation following the reduction of RhIII. In tpm and bpy systems, RhII intermediate is more stable than that in the tpy system. All three complexes were good light absorbers in the visible region and weak emitters from their emissive Ru(dπ)-'dpp(π*) 3MLCT (metal-to-ligand charge transfer) excited states at room temperature. The population of a low-lying 3MMCT (metal-to-metal charge transfer) ES (excited state) from the 3MLCT ES contributed to the weak emission, indicating an important intramolecular electron transfer process from dpp' to RhIII upon photoexcitation. The lower-lying 3MMCT excited state in the tpm and tpy systems relative to the bpy system result in a higher rate constant (ket = 2.6 x 10^7 vs 1.7 x 10^7 s-1) for intramolecular electron transfer. Spectrophotochemical analysis suggested that all three complexes were photoinitiated electron collectors capable of collecting two electrons on the RhIII center to generate the RuII,RhI species in the presence of DMA (N,N-dimethylaniline). The observed H2 production from water using [(bpy)2Ru(dpp)RhCl(tpm)](PF6)4 and [(bpy)2Ru(dpp)RhCl(tpy)](PF6)4 established that two halides on RhIII are not necessary in the dpp-bridge RuII,RhIII supramolecular photocatalytic-water-reduction system. This new discovery opens a new approach to the design of different RuII,RhIII motifs for photocatalysis. The active species for water reduction is proposed to be [(bpy)2Ru(dpp)RhICl(TL)]3+ from [(bpy)2Ru(dpp)RhCl(TL)](PF6)4 (TL (terminal ligand) = tpy or tpm) and [(bpy)2Ru(dpp)Rh(bpy)]3+ from [(bpy)2Ru(dpp)RhCl2(bpy)](PF6)3 respectively. Included here is the design and study of a RuII,RhI complex, [(bpy)2Ru(dpp)RhCl(COD)](PF6)3 (COD =1,5-cyclooctadiene) to provide more insights into the photophysical and photochemical properties of polypyridyl RuII,RhI species. Electrochemical and photophysical studies revealed a dpp-based LUMO in this RuII,RhI complex, suggesting dpp reduction upon photoexcitation. Photochemical study found that [(bpy)2Ru(dpp)RhCl(COD)](PF6)3 is an active photocatalyst for water reduction and that additional reduction(s) is (are) required after the generation of the RuII,RhI active species in the RuII,RhIII supramolecular photocatalytic H2 production system. This hypothesis was supported by the electrocatalytic behaviors of the RuII,RhIII supramolecular complexes for proton reduction. Cyclic voltammetry results in the presence of an acid suggested that the protonolysis of the RuII,RhIIH and RuII,RhIH species are electrocatalytic H2-evolution pathways. The mechanism is acid-dependent and influenced by terminal ligand. The studies of electrocatalytic proton reduction on these RuII,RhIII complexes suggested several possible intermediates involved in the photocatalytic water reduction cycle. The insights gained from this research can provide guidance in designing new type of RuII,RhIII and RuII,RhI complexes with better photocatalytic and/or electrocatalytic H2 production performance.
Ph. D.

Щедров, І. А. Маркетингові дослідження та бізнес-план створення підприємства з виробництва аксесуарів зі шкіри : дипломна робота : освітньо-професійна програма «Менеджмент» / І. А. Щедров ; керівник роботи С. В. Повна ; НУ "Чернігівська політехніка", кафедра менеджменту та державної служби. – Чернігів, 2021. – 66 с.
Об’єктом дослідження є процес маркетингових досліджень проникнення на зовнішні ринки підприємства з виробництва аксесуарів зі шкіри. Предметом дослідження є теоретичні, методичні та практичні аспекти створення бізнес-плану та маркетингової стратегії підприємства з виробництва аксесуарів зі шкіри. Мета і завдання дослідження. Метою дослідження є розробка бізнес-плану та маркетингових стратегій проникнення на ринки підприємства з виробництва шкіряних аксесуарів. Методи дослідження. Теоретичною і методологічною основою дослідження є праці вітчизняних та зарубіжних вчених з проблем формування маркетингових товарних стратегій та бізнес-планів підприємства. Дослідження ґрунтується на системному методі пізнання процесів і явищ.

This dissertation focuses on the development of analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) in water samples. Chemical analysis of PAHs is of great environmental and toxicological importance. Many of them are highly suspect as etiological agents in human cancer. Among the hundreds of PAHs present in the environment, the U.S. Environmental Protection Agency (EPA) lists sixteen as "Consent Decree" priority pollutants. Their routine monitoring in environmental samples is recommended to prevent human contamination risks. A primary route of human exposure to PAHs is the ingestion of contaminated water. The rather low PAH concentrations in water samples make the analysis of the sixteen priority pollutants particularly challenging. Current EPA methodology follows the classical pattern of sample extraction and chromatographic analysis. The method of choice for PAHs extraction and pre-concentration is solid-phase extraction (SPE). PAHs determination is carried out via high-performance liquid chromatography (HPLC) or gas chromatography/mass spectrometry (GC/MS). When HPLC is applied to highly complex samples, EPA recommends the use of GC/MS to verify compound identification and to check peak-purity of HPLC fractions. Although EPA methodology provides reliable data, the routine monitoring of numerous samples via fast, cost effective and environmentally friendly methods remains an analytical challenge. Typically, 1 L of water is processed through the SPE device in approximately 1 h. The rather large water volume and long sample processing time are recommended to reach detectable concentrations and quantitative removal of PAHs from water samples. Chromatographic elution times of 30 – 60 min are typical and standards must be run periodically to verify retention times. If concentrations of targeted PAHs are found to lie outside the detector's response range, the sample must be diluted (or concentrated), and the process repeated. In order to prevent environmental risks and human contamination, the routine monitoring of the sixteen EPA-PAHs is not sufficient anymore. Recent toxicological studies attribute a significant portion of the biological activity of PAH contaminated samples to the presence of high molecular weight (HMW) PAHs, i.e. PAHs with MW ? 300. Because the carcinogenic properties of HMW-PAHs differ significantly from isomer to isomer, it is of paramount importance to determine the most toxic isomers even if they are present at much lower concentrations than their less toxic isomers. Unfortunately, established methodology cannot always meet the challenge of specifically analyzing HMW-PAHs at the low concentration levels of environmental samples. The main problems that confront classic methodology arise from the relatively low concentration levels and the large number of structural isomers with very similar elution times and similar, possibly even virtually identical, fragmentation patterns. This dissertation summarizes significant improvements on various fronts. Its first original component deals with the unambiguous determination of four HMW-PAHs via laser-excited time-resolved Shpol'skii spectroscopy (LETRSS) without previous chromatographic separation. The second original component is the improvement of a relatively new PAH extraction method - solid-phase nanoextraction (SPNE) - which uses gold nanoparticles as extracting material for PAHs. The advantages of the improved SPNE procedure are demonstrated for the analysis of EPA-PAHs and HMW-PAHs in water samples via GC/MS and LETRSS, respectively.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

Organic ?-conjugated solids are promising candidates for new optoelectronic materials. The large body of evidence points at their advantageous properties such as high charge-carrier mobility, large nonlinear polarizability, mechanical flexibility, simple and low cost fabrication and superior luminescence. They can be used as nonlinear optical (NLO) materials with large two-photon absorption (2PA) and as electronic components capable of generating nonlinear neutral (excitonic) and charged (polaronic) excitations. In this work, we investigate the appropriate theoretical methods used for the (a) prediction of 2PA properties for rational design of organic materials with improved NLO properties, and (b) understanding of the essential electronic excitations controlling the energy-transfer and charge-transport properties in organic optoelectronics. Accurate prediction of these electro-optical properties is helpful for structure-activity relationships useful for technological innovations. In Chapter 1 we emphasize on the potential use of the organic materials for these two applications. The 2PA process is advantageous over one-photon absorption for deep-tissue fluorescence microscopy, photodynamic therapy, microfabrication and optical data storage owing to the three-dimensional spatial selectivity and improved penetration depth in the absorbing or scattering media. The design of the NLO materials with large 2PA cross-sections may reduce the optical damage due to the use of the high intensity laser beams for excitation. The organic molecules also possess self-localized excited states which can decay radiatively or nonradiatively to form excitonic states. This suggests the use of these materials in the electroluminescent devices such as light-emitting diodes and photovoltaic cells through the processes of exciton formation or dissociation, respectively. It is therefore necessary to understand ultrafast relaxation processes required in understanding the interplay between the efficient radiative transfer between the excited states and exciton dissociation into polarons for improving the efficiency of these devices. In Chapter 2, we provide the detailed description of the various theoretical methods applied for the prediction as well as the interpretation of the optical properties of a special class of substituted PPV [poly (p-phenylene vinylene)] oligomers. In Chapter 3, we report the accuracy of different second and third order time dependent density functional theory (TD-DFT) formalisms in prediction of the 2PA spectra compared to the experimental measurements for donor-acceptor PPV derivatives. We recommend a posteriori Tamm-Dancoff approximation method for both qualitative and quantitative analysis of 2PA properties. Whereas, Agren's quadratic response methods lack the double excitations and are not suitable for the qualitative analysis of the state-specific contributions distorting the overall quality of the 2PA predictions. We trace the reasons to the artifactual excited states above the ionization threshold. We also study the effect of the basis set, geometrical constraints and the orbital exchange fraction on the 2PA excitation energies and cross-sections. Higher exchange (BMK and M05-2X) and range-separated (CAM-B3LYP) hybrid functionals are found to yield inaccurate predictions both quantitatively and qualitatively. The failure of the exchange-correlation (XC) functionals with correct asymptotic is traced to the inaccurate transition dipoles between the valence states, where functionals with low HF exchange succeed. In Chapter 4, we test the performance of different semiempirical wavefunction theory methods for the prediction of 2PA properties compared to the DFT results for the same set of molecules. The spectroscopic parameterized (ZINDO/S) method is relatively better than the general purpose parameterized (PM6) method but the accuracy is trailing behind the DFT methods. The poor performances of PM6 and ZINDO/S methods are attributed to the incorrect description of excited-to-excited state transition and 2PA energies, respectively. The different semiempirical parameterizations can at best be used for quantitative analysis of the 2PA properties. The ZINDO/S method combined with different orders of multi-reference configuration interactions provide an improved description of 2PA properties. However, the results are observed to be highly dependent on the specific choice for the active space, order of excitation and reference configurations. In Chapter 5, we present a linear response TD-DFT study to benchmark the ability of existing functional models to describe the extent of self-trapped neutral and charged excitations in PPV and its derivative MEH-PPV considered in their trans-isomeric forms. The electronic excitations in question include the lowest singlet (S1) and triplet (T1†) excitons, positive (P+) and negative (P-) polarons and the lowest triplet (T1) states. Use of the long-range-corrected DFT functional, such as LC-wPBE, is found to be crucial in order to predict the physically correct spatial localization of all the electronic excitations in agreement with experiment. The inclusion of polarizable dielectric environment play an important role for the charged states. The particle-hole symmetry is preserved for both the polymers in trans geometries. These studies indicate two distinct origins leading to self-localization of electronic excitations. Firstly, distortion of molecular geometry may create a spatially localized potential energy well where the state wavefunction self-traps. Secondly, even in the absence of geometric and vibrational dynamics, the excitation may become spatially confined due to energy stabilization caused by polarization effects from surrounding dielectric medium. In Chapter 6, we aim to separate these two fundamental sources of spatial localization. We observe the electronic localization of P+ and P- is determined by the polarization effects of the surrounding media and the character of the DFT functional. In contrast, the self-trapping of the electronic wavefunctions of S1 and T1(T1†) mostly follows their lattice distortions. Geometry relaxation plays an important role in the localization of the S1 and T1† excitons owing to the non-variational construction of the excited state wavefunction. While, mean-field calculated P+, P- and T1 states are always spatially localized even in ground state S0 geometry. Polaron P+ and P- formation is signified by the presence of the localized states for the hole or the electron deep inside the HOMO-LUMO gap of the oligomer as a result of the orbital stabilization at the LC-wPBE level. The broadening of the HOMO-LUMO band gap for the T1 exciton compared to the charged states is associated with the inverted bond length alternation observed at this level. The molecular orbital energetics are investigated to identify the relationships between state localization and the corresponding orbital structure. In Chapter 7, we investigate the effect of various conformational defects of trans and cis nature on the energetics and localization of the charged P+ and P- excitations in PPV and MEH-PPV. We observe that the extent of self-trapping for P+ and P- polarons is highly sensitive on molecular and structural conformations, and distribution of atomic charges within the polymers. The particle-hole symmetry is broken with the introduction of trans defects and inclusion of the polarizable environment in consistent with experiment. The differences in the behavior of PPV and MEH-PPV is rationalized based on their orbital energetics and atomic charge distributions. We show these isomeric defects influence the behavior and drift mobilities of the charge carriers in substituted PPVs.
Ph.D.
Doctorate
Physics
Sciences
Physics

Si c’est la nouvelle américaine minimaliste qui a le plus souvent retenu l’attention, cette thèse s’intéresse à travers les nouvelles de William Gass, Steven Millhauser et David Foster Wallace à une écriture de l’expansion et de l’excès, qui fait pourtant de la réticence – à révéler et à conclure – sa pierre angulaire. Alors que la critique a souvent placé la nouvelle sous le signe de la restriction, comme un objet à l’économie poétique fondamentalement brève, notre corpus se départit nettement de cette vision. Les méandres de la voix, qui disent les introspections tortueuses du sujet au gré de boucles réflexives, les jeux de déclinaisons métaphoriques ainsi que la grammaire du détail, véritable tentative de maîtrise du monde par son atomisation, inscrivent ainsi l’esthétique de ces auteurs aux antipodes de l’écriture blanche. Se tisse alors une trame du ressassement, qui aspire à l’infini textuel et déjoue véritablement le telos. Cette renégociation singulière de la brièveté nourrit par ailleurs un régime philosophique de l’aporie, qui fait de la lecture une véritable expérience heuristique de l’indéterminé. C’est ainsi que les auteurs étudiés jouent constamment de la tendance du texte court à se dérober, tout en se refusant à une esthétique de la concision : l’examen de ce paradoxe apparent permettra dès lors de recontextualiser la notion de brièveté dans le champ de la nouvelle, tout en éclairant l’esthétique de ces trois auteurs. Ce faisant, cette thèse ambitionne de montrer comment l’assouplissement de la brièveté à l’œuvre informe une certaine épistémologie littéraire contemporaine dans les lettres américaines
While the minimalist short story has often been explored by contemporary criticism, this study wishes to focus on the resolutely more expansive and excessive style to be found in the shorter works of William Gass, Steven Millhauser and David Foster Wallace. Nonetheless, their stories guide the reader through an experience of reticence as they withhold the promise of revelation or resolution. Given that theoretical approaches to the short story are wont to emphasize its supposedly inherent concision, the stories of these three writers seem to deliberately transgress this preconception by consistently pushing their structural and metaphorical boundaries. Indeed, the texture of their narrative voices, depicting the tortuous introspections of characters prone to highly reflexive discourses, the constant weaving of poetic leitmotive as well as an omnipresent thirst for detail shape a prose which asserts itself as a firm counterpoint to minimalism. This constant renegotiation of what brevity means also fuels the philosophical tenets of their prose, often characterized by various aporetic patterns and considerations which confront the reader with a heuristic approach to indeterminacy. Gass, Millhauser and Wallace therefore constantly play with the implications of brevity in their stories, which are neither short nor concise, thereby contributing to the definition of a new literary epistemology in the context of contemporary American literature

Les proprietes magneto-optiques de structures semiconductrices de puits quantiques gaas/gaalas en modulation de dopage ont ete explorees. Avec des systemes dopes p, les proprietes individuelles de l'electron ont ete etudiees par photoluminescence et excitation de photoluminescence en configuration de faraday et de voigt. Les effets du melange des bandes et de remplissage ont ete identifies. Une methode d'evaluation du facteur de lande effectif de l'electron est proposee, et les mecanismes de la relaxation du spin electronique sont determines. Les effets collectifs d'un gaz d'electrons sont explores en configuration de faraday sur des systemes dopes n par l'analyse de l'intensite de luminescence de la premiere sous-bande electronique excitee. Un mecanisme d'inhibition de la relaxation inter-sous-bande et la manifestation du decalage de spin non-lineaire en champ magnetique sont mis en evidence. Un modele simple d'equation de bilan des populations de niveaux de landau confirme ces interpretations. Un processus de type auger est egalement identifie. Un comportement singulier autour du facteur de remplissage unite est caracterise, et l'hypothese de la formation de skyrmions est avancee pour interpreter ce phenomene

Lesotho Revenue Authority became operational in January 2003, when introducing the Authority the main aim was to increase revenue effectively through acquisition of skilled staff, increase integrity and effective use of automated systems. However, it seems that some of the systems that the department employs to collect revenue are not effective. There are no legal frameworks in place to ensure that regulations are enforceable. Performance appraisal is not practiced. There is no adequate publicity to make taxpayers aware of tax policies and compliance. This paper examines the effectiveness of tax collection system at customs and excise. This study is a qualitative case study approach. Most of the primary data will be collected from the use of open ended questionnaires and in-depth interview schedules which make an allowance to a greater internal between the researcher and the interviewee. A sample of 50 employees was used with the objective that employees were chosen on the basis of knowledge of the organisation and therefore purposive sampling was used. Descriptive statistics was used to analyse data and it included frequency distribution whereby the responses were presented in a tabular form and bar charts. The research findings revealed that department of Customs and Excise does not have an effective system for its collection of tax. Their administration is very poor performance appraisal is not practiced and there is not enough publicity on tax policies and compliance. In order to improve the effectiveness of the system, Customs and Excise should consider setting new policies and regulations which are in line with their current operation. Performance appraisal and reward system should also be taken into consideration to improve efficiency among the employees and lastly the use of different radio stations should be considered as awareness campaign on tax policies and compliance.
Thesis (MBA)-University of KwaZulu-Natal, 2007.