VictorJuiz/thesis huggingface dataset:
Studies of reactions relevant to atmospheric photochemistry

Three main catalytic chain processes are believed to contribute to the loss of ozone in the stratospheric region of the earth's atmosphere. These are the HOx , the ClOx and the NOx catalytic processes. This thesis describes experiments conducted to elucidate mechanisms involved in the first two of these; the HOx and the ClOx chain processes. In addition the efficiency of energy transfer from O(1D) to molecular oxygen is measured.
A fast-flow/photolysis system with mass spectrometric detection has been developed to study the reactions of O(1D) generated by the photolysis of ozone at 2537Å. The method of relative quantum yields, wherein the quantum yield for loss of ozone in a series of reactions is quantitified by reference to the loss of ozone in the photolysis of O3/N2 and O3/He mixtures, is used to monitor ozone loss. Under suitable concentration-time conditions the relative quantum yield for ozone loss in the photolysis of O3/N2 and O3/He mixtures is 1.0 and 2.0, respectively.
From measurement of the relative quantum yield for ozone loss in oxygen carrier gas the efficiency of energy transfer to produce O2(1∑g+) in the reaction O(1D) + O per O(1D) atom deactivated is found to be 0.63 &pm; 0.18.
Observations of the relative quantum yield for ozone loss in the photolysis of O3/H2 mixtures in helium carrier gas failed to show any evidence for the occurence of a catalytic chain process. On this basis it is believed that the reaction of vibrationally excited OH* , produced by the reaction H + O3, with ozone does not generate H atoms as products. The observations are consistent with the reaction OH* + O3 producing HO with unit efficiency. This result implies that the Norrish mechanism is the one most likely to subsist in the HOx catalytic loss of ozone in the gas phase.
The rate of quenching of O(1D) by sulphurhexafluoride relative to the rate of reaction with ozone is found to be (2.1 &pm; 1.0) x 10-4 from observations of the relative quantum yield for the photolysis of ozone in SF6 carrier gas. Qualitative observations show that the relative rate of quenching of O(1D) by carbon tetrafluoride is unlikely to be significantly faster than this.
The relative quantum yields for the photolysis of ozone in the helium carrier gas and in the presence of CF3CL, CF2Cl2, CFCl3 and CCl4 are found to be ca 1.5 , 2.0, 1-2 (dependant on [O3] and t , and 2-4 , respectively. The quantum yields for the photolysis of CF3Cl/O3, CF2Cl2/O3 and CFCl3/O3 mixtures show an increase on addition of nitric oxide. This is interpreted in terms of a catalytic chain involving formation of ClO by abstraction of chlorine fronythe freon by O(1D), the reaction ClO + NO &longrightarrow; Cl + NO2 and regeneration of ClO in the reaction Cl + O3. Calculation shows that the efficiency for ClO production in the reaction O(1D) + CF2Cl2 is approximately 0.3. The other major reaction pathway is believed not to be physical quenching of O(1D). Observation of a product peak at m/e &simeq; 66 is interpreted in terms of the production of chlorine dioxide in the second reactive pathway.
The first component of human complement

1. Procedures for partial purification of C1 and Cī are described and methods for the isolation of subcomponents C1r and C1s from C1 and Cī preparations have been developed.
2.1. Structural studies of C1r derived from C1 and Cī have shown that C1r, like C1s, exists in serum as a proenzyme, which is activated by limited proteolysis.
2.2. C1r and C1s are both single polypeptide-chain zymogens of 83,000 molecular weight with similar amino acid compositions. They are distinct in carbohydrate composition and antigenic properties. Activation of C1r and C1s occurs without loss of glycopeptides but loss of small peptides may occur.
2.3. C1r̄ and C1s̄ bind one mole of DFP per mole of protein. The amino acid sequences of the first 20 residues of the 26,000 molecular weight diisopropylphosphate-binding polypeptide chains of C1r̄ and C1s̄ show a high degree of sequence identity with corresponding regions of serine proteases such as trypsin and plasmin. C1r̄ and C1s̄ are therefore identified as serine proteaces of similar size and structure to plasmin. The structure and mode of activation of C1r and C1s and other serine protease zymogens are compared.
3.1. The enzymic activities of C1r̄ and C1s̄ have been investigated. C1r̄ cleaves C1s but did not hydrolyse any synthetic substrate tested. C1s̄ cleaves C2 and C4 and hydrolyses several amino acid esters. The proteolytic specificities of C1r̄ and C1s̄ are discussed.
3.2. Rapid and convenient assays for C1r̄ and C1s̄, suitable for kinetic studies of zymogen activation, have been developed.
4.1. The interactions of C1q, in solution or bound to antibody-antigen complexes, with C1r and C1s have been examined.
4.2. In solution, C1r and C1s form strong Ca2+-dependent complexes containing 2C1r + 2C1s molecules, or 4C1r + 4C1s molecules. C1r, C1s and the C1r-C1s complexes interact weakly with C1q.
4.3. When C1q is bound to immune complexes, C1r and C1r-C1s complexes bind strongly to C1q. C1s does not bind to C1q in the absence of C1r
4.4. Activation of C1r and C1s does not appear to alter their binding affinity for other subcomponents either in solution or when bound to antibody-antigen.
5.1. Spontaneous activation of C1r and C1s in solution has been studied. C1s does not activate autocatalytically. Absolute stability of C1r preparations was not observed, but it is concluded that auto-activation of C1r does not contribute significantly to the instability of C1r.
5.2. When fixed to antibody-antigen-C1q complexes, C1r does not activate unless C1s is also present. The effect of C1s on C1r activation does not require C1s̄ enzymic activity and it is apparent that C1s fulfills a binding requirement.
5.3. The mechanism of activation of C1 on interaction with immune complexes is discussed.
Aspects of organophosphorus chemistry

Chapter 1 This chapter is concerned with some reactions of diphenylvinylphosphine oxide (1). Phosphine oxfide (1) is known to undergo nucleophilic additions analogous to the Michael reaction. Triphenylvinylphosphonium bromide also undergoes a number of nucleophilic additions, including the Schweizer reaction. Thus, Triphenylvinylphosphonium bromide, upon treatment with the sodium salts of benzoin or salicylaldehyde, yields 2,3-diphenyl 2,5-dihydrofuran and 3,4-chromene, respectively. An attempt to extend the Schweizer reaction to phosphine oxide (1) was not not successful.
Several possible synthetic routes to epoxyvinyldiphenylphosphine oxide (2) have been explored.
Phosphine oxide (1) was found to be inert to several epoxidising conditions, for example, unbuffed trifluorperoxide/Triton B in methanol. Phosphine oxide (1) was converted to bis-(2-diphenylphosphinylethyl)peroxide (3) in 79% yield, by treatment with alkaline hydrogen peroxide. Peroxide (3) is usually stable. Reaction of (3) with lithium aluminium hydride gave 2-hydroxyethyl diphenylphosphine oxide (4) in 84% yield.
Phosphine oxide (1) was converted to 1,2-bis-(diphenylphosphinyl)ethane (5) upon treatment with aqueous methanolic sodium hydroxide, in 96% yield. Phsophine oxide (5) had also previously been obtained by the reaction of triphenylvinylphosphonium bromide with sodium hydroxide. Phosphine oxide (5) was alos isolated in 19% yield from the treatment of phosphine oxide (4) with two mole equivalents of butyllithium, and subsequent treatment with bromine (Scheme 1).
Scheme 1
On the basis of the spectroscopic properties of phosphine oxide (1), it is considered that there is little congugation between the C=C and hte P=O groups. [please see pdf for full abstract]
Study of reactions between heavy nuclei

A semi classical approach, has been used to study those reactions between heavy nuclei (or "heavy ions" as they are more commonly referred to) in which a single nucleon or a single cluster of nucleons is transferred from one nucleus to the other. A method has been developed for evaluating transfer amplitudes for the transfer of a neutron using the semi classical theory of Brink and Pixton. As this leads to a tedious three dimensional integral, we have developed another method for the same calculation. It is found that if we work in momentum space and assume a straight line trajectory for the relative motion, the expressions simplify considerably and we are left with a straightforward single integral for the transfer amplitude. An added advantage is that the formulae are exactly the same in the post and prior representations. The theory has then been generalised for the transfer of a charged particle. Some numerical calculations have been performed for the reaction 208Pb(11B, 10B)209Pb at 114 MeV laboratory energy. A comparison of the transfer amplitudes calculated in the post and prior representations using the first method has been made. The agreement is reasonably good between these two results as well as between these and the results using the second method.
We go on to set up a semi classical theory for evaluating angular distributions. The starting point is the expression of the transition matrix in DWBA. A partial wave expansion is made for the distorted waves and the WKB approximation used for the radial wave functions. Further simplifications are made resulting in a formula for the transition amplitude which is a partial wave sum containing a term recognisable as the semi classical transfer amplitude evaluated earlier.
The method has been used to calculate angular distributions for the reactions 26Mg(11B, 10B)27Mg and 26Mg(11B, 10Be)27Ai at 114MeV laboratory energy. A detailed numerical study of the formula shows some interesting features which enable us to approximate the transfer amplitude by a simple parametrised exponential formula. The resulting angular distributions are compared with experiment showing good agreement. A parametrisation of the elastic scattering phase shifts as well make it possible to obtain a closed expression for the angular distribution. A numerical comparison of the angular distribution obtained from this formula is made with former results. The agreement is good.
We also study the theoretical reaction 160(170*, 160)170* for a range of energies from 212.5 MeV to 37.1875 MeV and compare our results with that using the quantum mechanical code LOLA of De Vries (DeVries, 1973). The elastic scattering phase shifts are calculated in a potential with an energy dependent imaginary part. The agreement is good till 53.125 MeV. At 37.1875 MeV there is disagreement. This is attributed to the breakdown of our formalism for weakly absorbing potentials.
Some calculations have been performed for the α-particle transfer reaction 160(16
0, 12C)20Ne. Comparison with LOLA shows disagreement which we have not been able to explain.
Asymptotic properties of the branching random walk

The branching random walk is a Galton-Watson process with the additional feature that people have positions. The initial ancestor is at the origin. Let {3(1)r} be the positions on the real line of his children. The people in the nth generation give birth independently of one another and of the preceeding generations to form the (n+1)th generation and the positions of the children of an nth generation person at x has the same distributions as {3(1)r+x} . Let {3(n)r} be positions of the nth generation people in this process.
In the first chapter the convergence of certain martingales associated with this process is examined. A generalization of the Kesten-Stigum theorem for the Galton-Watson process is obtained. The convergence of one of these martingales is shown to be closely related to some known results on the growth rate of age-dependent branching process.
If B(n) is the position of the person on the extreme left of the nth generation then it is shown in the second chapter that B(n)/n &rightarrow;γ for some constant γ when the process survives. Subsequent chapters are generalizations of this result. Thus the same result holds for a multitype process with a finite number of different types and a weaker result holds when there is a countable number of different types. The generalization to the branching random walk on ℝP is also considered. Let C(n) be the set of points {3(n)r/n:r}. It is shown that there is a compact convex set C such that C(n)Δ&rightarrow;C when the process survives where Δ is a suitable metric on the compact subsets of ℝP .(All of these results are proved under the 'natural' conditions.)
Genetical and biochemical investigations on the regulation of cystein biosynthesis in Escherichia coli

This thesis is concerned with the mechanism by which the enteric bacterium Escherichia coli regulates its synthesis of the amino acid cysteine. The structural genes for the enzymes of the pathway are located at various positions around the chromosomes of both this organism and the closely related Salmonella typhimurium. Mutations in the cys B region of both organisms cause a deficiency of the cysteine biosynthetic enzymes. We concentrated our efforts on this region in E. coli. Previous work had shown that cys B mutations in E. coli were recessive to wild type and a scheme of positive control of cysteine biosynthesis via the cys B gene product(s) had been proposed. Genetical and nutritional analysis of the cys B region in Salmonella had indicated that it was complex, possibly containing three genes.
Optimal conditions were found for a method of directed mutagenesis in E. coli using mutagenised transducing phage PI. This technique was then used to isolate 60 point mutants in the cys B region. Nutritional and genetical analyses confirmed that they lay in cys B.
We isolated in addition a number of deletions extending into the cys B region of an E. coli F-prime carrying tho cys B and trp genes which had been inserted into S. typhimurium. These were used to construct a map and thus to order the point mutations into 16 deletion groups. Point mutations mapping at the extreme ends of the region were unable to complement one anorher. This result shows that there is only one gene in the cys B region. Nutritional data correlates with this conclusion.
Some of the point mutants are temperature sensitive and in others the mutations are suppressed by the amber suppressor sup F: the gene therefore codes for a protein.
Deletions ending in cys B and trp were isolated. We measured the rate of synthesis of enzymes of the tryptophan operon in strains carrying such deletionso In none of them was the expression of trp brought under cysteine-mediated control. We tentatively concluded that the cys B gene is transcribed in the direction trp → cys or, if it is transcribed in the direction cys → trp it is transcribed at a low, constant rate.
We also sought constitutive mutations mapping in the cys B region. We isolated several mutants constitutive for at least part of the pathway: though the mutations conferring this phenotype were associated with the cys B region, they were unstable and their nature could not be elucidated.
The results obtained in this thesis, together with recent work locating a partial constitutive mutation within the cys B region of Salmonella are strong evidence that cysteine biosynthesis in both organisms is indeed under positive control mediated via the cys B gene product.
The dynamic Pseudo-Jahn-Teller problem in cubic symmetry and a vibronic model for the relaxed excited state of the F centre in some alkali halides

The results of recent experiments on Stark effects in F-band luminescence of various alkali halides have suggested a model for the relaxed excited state of the F centre in which non-degenerate 2s and 2p electronic states interact in cubic symmetry via a triply degenerate odd-parity (Tlu)vibrational mode. A general exact solution of this vibronic problem has been given by Ham (1973a).
We extend the work by a numerical investigation of this ideal pseudo-Jahn-Teller problem. Vibronic energy levels and wave functions, emission spectra at various temperatures, absorption lines and spectra at T=0, and reduction factors are calculated for various values of the vibronic coupling strength and of the electronic 2s-2p spacing. The results are compared with explicit expressions of the weak and strong coupling limit. In addition, the absorption line shape is calculated in semi-classical approximation.
The relaxed excited state of the F centre is investigated within this model by a perturbation analysis for the case of weak electron-phonon coupling. The resulting predictions are compared with available data on radiative lifetimes, Stark effects, magnetic circular polarization, and stress-induced polarization of F-band luminescence. It is shown that a consistent quantitative interpretation of most of these data is possible on this basis if the 2s electronic state lies below the 2p state in the relaxed cubic configuration.
Structural studies on fibrous biological material

This work is concerned with the structure, self-assembly and sequence of collagen. The complete amino acid sequence of the αl chain, as found in the collagen triple-helical molecular structure, is used in the following three ways. First, the electron microscopic, banding patterns, of the many ordered forms of intermolecular collagen assembly, are simulated on the basis of the known distribution of charged residues in the sequence (Chapters 2 and 3). In this way, various models, for the axially projected structures of these forms, are tested. The result is a set of experimentally determined intermolecular staggers or overlaps. Secondly, the distribution of residues along the sequence is analysed to find the origins of collagen self-assembly (Chapters 2 and 3). The specificity for each structure is due to the patterns of interacting residues along the sequence. Different residues, hence different distributions, seem to be important for each structure, depending on the physicochemical conditions of the mainly in vitro precipitations. Thirdly, the sequence is used to predict the meridional X-ray and neutron diffraction patterns from rat tail tendon (Chapter 4). There is substantial agreement with the observed patterns. This creates the possibility of interpreting the changes in meridional intensities, in terms of the sequence, from collagen fibrils in a variety of tissues and in many metabolic states.
Some Factors Affecting Respiration in Man

It has been proposed that the naturally-occurring respiratory oscillation in Pa,CO2 carries sufficient information on the rate of metabolism to be implicated in the generation of the hyperpnoea of hypoxic exercise. As a PCO2 signal of this frequency can be transduced by the carotid chemoreceptors but not by those of the medulla, it would be of interest to examine the manner in which hypoxia and a CO2 transient interact at the carotid body.
In the present study the responses of healthy subjects to an induced PA,CO2 oscillation (of two breaths' period) were examined against a background of graded hypoxia at rest and during moderate rhythmic exercise. The responses were measured on a breath-by-breath basis in a variety of inspiratory and expiratory variables including times, volumes, ventilations and flows.
In brief it was found that:-
oscillating responses were largely confined to PA,O2 less than 72 torr;
their incidence in hypoxia was potentiated by exercise;
FRC oscillated, on average, more consistently than any other output variable;
at times, an inspiratory stimulation occurred on the same breath as an expiratory depression;
a linear multiplication between hypoxia and the PA,CO2 oscillation was occasionally observed, the amplitude of the response increasing as hypoxia became more intense. Linear muliplication was more frequent in exercise.
The patterns of oscillating responses were interpreted in terms of a carotid body involvement, with hypoxia and the PCO2 oscillation multiplying at receptor level, and a subsequent degree of complexity being introduced by the central timing of the carotid body discharge at the brain-stem. The potentiating effects of exercise may have resulted from a reduced attenuation of the PCO2 oscillation in transit from the lung to the carotid body, and an improved central timing of the carotid body discharge.
Production planning and design in the pressure vessel industry

The Pressure Vessel Industry is quite unique in having a number of rigid Codes introduced and accepted in order to safeguard the integrity of the product rather than the efficient use of the fabrication facilities. Such Codes facilitate the task of designers and thus result in an economy of time and effort during the design stage. On the other hand their intrinsic lack of flexibility demands, for example, expensive inspection procedures which, sometimes, can not be substantiated by sound scientific reasoning. Also peculiar to this situation is the existence of licencing or insuring authorities, making radical departures from the Codes virtually impossible in many cases and unjustified by the possible saving in materials in most. This being so, it follows that any cost reduction must be made within the framework of the Design Codes.
This thesis summarises an investigation whose purpose was to evaluate the time and cost involved in design, fabrication and inspection depending on the codes.
It is concluded that the only significant savings can be achieved through careful planning of production and that the only advantage that a design code can offer is a reduction of weight by allowing a higher design stress.
Property and Rawlsian justice

What property institutions should be taken to characterize a society which is, by Rawlsian standards, just? The aim of my thesis is to answer this question. The thesis does so by focusing on three central questions of property and Rawlsian justice. The first is whether Rawlsian political philosophy should include a basic right to privately own or be eligible to privately own personal property. The second is whether Rawlsian political philosophy should include a basic right to privately own or be eligible to privately own productive property. The third is whether Rawlsian political philosophy should defend – on grounds other than a commitment to basic rights – the claim that all citizens should have a stake in the means of production. I answer these questions by doing two things. Firstly, I develop an account of what basic property rights a Rawlsian account of justice should include. With respect to the things normally taken to fall under a basic right to personal property – housing and personal items – I argue that Rawlsian justice should include a basic right to rent, rather than to own, these things. In the thesis, I spell out what a basic right to rent should be taken to consist in. I also argue that Rawlsian justice should not be understood to include a basic right to productive property of any sort. Secondly, I argue that Rawlsian political philosophy should not defend – on grounds other than a commitment to basic rights – the claim that all citizens should have a stake in the means of production. In making these arguments, the thesis claims that the Rawlsian view, properly understood, places less overall emphasis on the importance of ownership than has often been thought.

Advisor: White, S