The kinetics of elementary reactions

The fundamental aim of the work contained in this thesis is the better understanding of the factors that govern the rates of chemical reactions. Most of the work is concerned with the investigation of reactions in the gas phase, because homogeneous gas reactions may be expected to yield most readily to theoretical treatment. True gas reactions are free from such complicating factors as solvatiot, adsorption and, except in special cases, diffusion. There are however some solution reactions which might be simple; they are the reactions for which the transfer of a proton is the rate- determining step. Some of the work in this thesis is concerned with reactions of this type. It will be seen from the published papers that the most complex experimental techniques are often required to investigate the reactions of greatest formal simplicity. The rate constants of these simple reactions can usually only be measured when the experimental systems are carefully designed for this specific purpose.Book. • Gas Kinetics: An Introduction to the Kinetics of Homogeneous Gas Reactions. • • Published Papers. • 1. The Reactions of Methyl Radicals. • 2. Entropy Changes in Free Radical Reactions. • 3. Studies in Energy Transfer II. The Isomerization of Cyclopropane -a quasi- Unimolecular Reaction. with H.O.Pritchard and R.G.Sowden. • 4. Studies in Energy Transfer III. The Effect of Added Gases on the Decomposition of Cyclobutane. with H.O.Pritchard and R.G.Sowden. • 5., The Thermal Decomposition of Azomethane. with H.O.Pritchard and M.Page. • 6. The Thermal Decomposition of t- Butylamine. with H.O.Pritchard and R.G.Sowden. • 7. The Reactions of Methyl Radicals with Acetone, Diethyl Ketone and Di -t -butyl Peroxide. with G.O.Pritchard and H.O.Pritchard. • 8. The Exchange of Iodine Atoms between Iodine and Methyl Iodide in the Temperature Range 150 -3751). with D.Clark and H.O.Pritchard. • 9. The Study of Chlorine Atom Reactions in the Gas Phase. with H.O.Pritchard and J.B.Pyke. • 10. The Reactions of Trifluoromethyl Radicals. with G.O.Pritchard, H.O.Pritchard and H.I.Schiff. • 11. The Thermal Decomposition of Cyclopentyl Bromide. with S.J.W.Price and R.Shaw. • 12. The Reactions of Chlorine Atoms - A Test of the Transition State Theory. with J.H.Knox. • 13. The Crystal Structure of Nitramide, NH2NO2. with C .A .Beevers. • 14. Recent Developments of Gas Kinetics. • • General. • 15. The Teaching of Chemical Kinetics. Shorter Contributions. • 16. A Method for the Study of Chlorine Atom Reaction. The Reaction Cl - CH4 -- CH3 _ HC1. with H.O.Pritchard and J.B.Pyke. • 17. The Photolysis of Acetaldehide. with G.O.Pritchard and H.O.Pritchard. • 18. The C -C Bond Dissociation Enegies in Cyclanes. with H.O.Pritchard. • 19. The C -C Bond Dissociation Energy in Cyclobutane. with H.O.Pritchard. • 20. The Photolysis of Hexafluoroazomethane and the Reactions of CF Radicals with Methane and nButane. with G.O.Pritchard,and H.O.Pritchard. • 21. The C -H Bond Dissociation Energy in Fluorofom. with G.O.Pritcha.rd, H.O.Pritchard and H.I.Schiff. • 22. The Reactions of Methylene. with J.H.Knox. • 23. The Isomerization of Cyclopropane at very low Pressures. with H.O.Pritchard and R.G.Sowden. • 24. The Combination of Nitrogen Atoms. with G.Boocock and H.O.Pritchard. • • Papers in the course of publication. • 25. Carbon -Metal Bonds I. The Pyrolyses of Dimethyl Mercury and Dimethyl Cadmium. with S.J.'rA.Price. • 26. Carbon Metal Bonds 2. The Pyrolysis of Dimethyl Zinc. with S.J.W.Price. • 27. The Decomposition of Nitramide in Anisole Catalysed by Anilines. with G.C.Fettes, J.A.Kerr, A.McClure, J.S.älater and C.Steel. • 28. The Photoinitiated Decomposition of Acetaldehyde Catalysed by Thiols. with R.N.Birrell, R.F.Smith and H.Wilkie. • 29. The Pyrolysis of t -Butyl Forrñate. with R.Gordon and S. J. W. Price. • 30. The Study of Free Radical Reaction by Competitive methods. with J.H.Knox. • 31. The Reactions of Methylene with Alkanes, with J.H.Knox. • 32. The Reactions of Methyl Radicals with Thiols. with J.A.Kerr

The development of the Scottish industrial estates 1936-52

The industrial estates sponsor- ed by the British government are of interest both as novel measures for dealing with unemployment and as tools of econo- mic planning. Their object before the Second World War was primarily to provide employment in regions which had suffered from prolonged unemployment and underemployment . After the war, as Jobs were plentiful, the main emphasis was on the diversification of industry within the areas. It was hoped that future unemployment, which might have arisen from over- dependence of the regions on a small number of industries, would be minimised. Consequently the industrial estates were to play an important role in employment policy and in the planning of industrial location.The survey of the Scottish Industrial Estates is divided into parts dealing in turn with the history, organisation, powers, finance and functions of the Scottish Industrial Estates Ltd., with the Scottish Industrial Estates and their development, and with the firms and labour on the estates. The effectiveness of the Scottish Industrial Estates in reducing unemployment and introducing new industries to Scotland is discussed. The advantages and disadvantages of the industrial estates are examined.In this report an attempt is made to show trends and to draw broad conclusions as information which would have permitted a more detailed study of the Scottish Industrial Estates was not available. The S.I.E.Ltd. and the Treasury have not been in a position to disclose facts about the finance of the company. Such information on this subject, as is presented here, has been extracted from the public records at the office of the Company Registrar, Edinburgh. Data which could be obtained about the firms on the estates from the Board of Trade, or on labour from the Ministry of Labour have been limited by the Factory Statistics Act.This study of the Scottish Industrial Estates Ltd. suggests the conclusion that the 'experiment' of establishing the government sponsored industrial estates was worth making. It does not appear however that the 'experiment' was conducted by the government in such a way that the results could be ascertained in concrete terms. More detailed information on labour and industrial would have been necessary. No information seems to have been collected on the rate of growth of the different industries in the Development Areas and in the country as a whole. it docks not appear that an effort was made to obtain information on such subjects as the production or distribution costs in various locations. Some information which has been gathered has not been released. In particular a comparison of the performance of the four industrial estates estates companies would have been interesting. The government attached great importance to the policy of establishing of the estates. The public was led to expect much of it, but the public has been given insufficient information to judge whether its expectations have been fulfilled. This is all the more regrettable because the information gathered in the course of this research points to the conclusion that the Scottish Industrial -estates have been well managed and successful. They represent a method b: which the government may control the economy without the disadvantages of directives or nationalisatton

Early Lung Function Abnormalities in Acromegaly.

BACKGROUND: Acromegaly is an insidious disorder caused by a pituitary growth hormone (GH)-secreting adenoma resulting in high circulating levels of GH and insulin-like growth factor I (IGF-I). Respiratory disorders are common complications in acromegaly, and can severely impact on quality of life, eventually affecting mortality. OBJECTIVES: The present study aimed to explore structural and functional lung alterations of acromegalic subjects. METHODS: We enrolled 10 consecutive patients (M/F: 5/5) affected by acromegaly. In all patients, magnetic resonance imaging (MRI) revealed the presence of pituitary tumor. All patients underwent clinical, lung functional, biological, and radiological assessments. Ten healthy age-matched subjects also served as controls. RESULTS: No statistically significant differences in lung function were detected between acromegalic and healthy subjects (p ≥ 0.05 for all analyses). However, the diffusing capacity for CO (TLCO) was significantly lower in the acromegalic group than in healthy subjects (TLCO% predicted: 78.1 ± 16 vs. 90 ± 6 %, respectively, p = 0.04; KCO% predicted: 77 ± 16 vs. 93 ± 5 %, p = 0.02, respectively). None of the lung function parameters correlated with duration of the disease, or with inflammatory marker of the airways. In acromegalics, biological (exhaled NO concentrations) and imaging (total lung volume, TLV, and mean lung density, MLD) evaluations were within normal values. The TLV measured by HRCT was 3540 ± 1555 ml in acromegalics, and the MLD was -711 ± 73 HU. None of the lung functional, radiological, and biological findings correlated with GH or IGF-I levels, and no correlation was found with duration of disease. CONCLUSIONS: In the current study, lung function evaluation allowed to detect early involvement of lung parenchyma, as assessed by TLCO and KCO, even in the absence of parenchymal density alterations of the lung by HRCT. These findings suggest to routinely include the carbon monoxide diffusing capacity in the lung function assessment for an early intervention in acromegaly

Chest radiography practice in critically ill patients: a postal survey in the Netherlands

BACKGROUND: To ascertain current chest radiography practice in intensive care units (ICUs) in the Netherlands. METHODS: Postal survey: a questionnaire was sent to all ICUs with > 5 beds suitable for mechanical ventilation; pediatric ICUs were excluded. When an ICU performed daily-routine chest radiographs in any group of patients it was considered to be a "daily-routine chest radiography" ICU. RESULTS: From the number of ICUs responding, 63% practice a daily-routine strategy, in which chest radiographs are obtained on a daily basis without any specific reason. A daily-routine chest radiography strategy is practiced less frequently in university-affiliated ICUs (50%) as compared to other ICUs (68%), as well as in larger ICUs (> 20 beds, 50%) as compared to smaller ICUs (< 20 beds, 65%) (P > 0.05). Remarkably, physicians that practice a daily-routine strategy consider daily-routine radiographs helpful in guiding daily practice in less than 30% of all performed radiographs. Chest radiographs are considered essential for verification of the position of invasive devices (81%) and for diagnosing pneumothorax, pneumonia or acute respiratory distress syndrome (82%, 74% and 69%, respectively). On demand chest radiographs are obtained after introduction of thoracic drains, central venous lines and endotracheal tubes in 98%, 84% and 75% of responding ICUs, respectively. Chest films are also obtained in case of ventilatory deterioration (49% of responding ICUs), and after cardiopulmonary resuscitation (59%), tracheotomy (58%) and mini-tracheotomy (23%). CONCLUSION: There is notable lack of consensus on chest radiography practice in the Netherlands. This survey suggests that a large number of intensivists may doubt the value of daily-routine chest radiography, but still practice a daily-routine strategy

Insights to scaling remote plasma sources sustained in NF3 mixtures

Remote plasma sources (RPSs) are being developed for low damage materials processing during semiconductor fabrication. Plasmas sustained in NF3 are often used as a source of F atoms. NF3 containing gas mixtures such as NF3/O2 and NF3/H2 provide additional opportunities to produce and control desirable reactive species such as F and NO. In this paper, results from computational investigations of RPS sustained in capacitively coupled plasmas are discussed using zero-dimensional global and two-dimensional reactor scale models. A comprehensive reaction mechanism for plasmas sustained in Ar/NF3/O2 was developed using electron impact cross sections for NF2 and NF calculated by ab initio molecular R-matrix methods. For validation of the reaction mechanism, results from the simulations were compared with optical emission spectroscopy measurements of radical densities. Dissociative attachment and dissociative excitation of NFx are the major sources of F radicals. The exothermicity from these Franck–Condon dissociative processes is the dominant gas heating mechanism, producing gas temperatures in excess of 1500 K. The large fractional dissociation of the feedstock gases enables a larger variety of end-products. Reactions between NFx and O atom containing species lead to the formation of NO and N2O through endothermic reactions facilitated by the gas heating, followed by the formation of NO2 and FNO from exothermic reactions. The downstream composition in the flowing afterglow is an ion–ion plasma maintained by, in oxygen containing mixtures, [F−] ≈ [NO+] since NO has the lowest ionization potential and F has the highest electron affinity among the major neutral species

Non-emphysematous chronic obstructive pulmonary disease is associated with diabetes mellitus

Background: Chronic obstructive pulmonary disease (COPD) has been classically divided into blue bloaters and pink puffers. The utility of these clinical subtypes is unclear. However, the broader distinction between airway-predominant and emphysema-predominant COPD may be clinically relevant. The objective was to define clinical features of emphysema-predominant and non-emphysematous COPD patients. Methods: Current and former smokers from the Genetic Epidemiology of COPD Study (COPDGene) had chest computed tomography (CT) scans with quantitative image analysis. Emphysema-predominant COPD was defined by low attenuation area at -950 Hounsfield Units (LAA-950) ≥10%. Non-emphysematous COPD was defined by airflow obstruction with minimal to no emphysema (LAA-950 < 5%). Results: Out of 4197 COPD subjects, 1687 were classified as emphysema-predominant and 1817 as non-emphysematous; 693 had LAA-950 between 5-10% and were not categorized. Subjects with emphysema-predominant COPD were older (65.6 vs 60.6 years, p < 0.0001) with more severe COPD based on airflow obstruction (FEV1 44.5 vs 68.4%, p < 0.0001), greater exercise limitation (6-minute walk distance 1138 vs 1331 ft, p < 0.0001) and reduced quality of life (St. George's Respiratory Questionnaire score 43 vs 31, p < 0.0001). Self-reported diabetes was more frequent in non-emphysematous COPD (OR 2.13, p < 0.001), which was also confirmed using a strict definition of diabetes based on medication use. The association between diabetes and non-emphysematous COPD was replicated in the ECLIPSE study. Conclusions: Non-emphysematous COPD, defined by airflow obstruction with a paucity of emphysema on chest CT scan, is associated with an increased risk of diabetes. COPD patients without emphysema may warrant closer monitoring for diabetes, hypertension, and hyperlipidemia and vice versa