The usual procedure employed in enzyme kinetic analysis is the method of initial rates. However, it has been appreciated for years that the analysis of enzyme-catalyzed reactions could, in principle, be more efficiently performed by examining the entire time course. There is much more information contained in a progress curve than in a simple initial rate. With the appearance of the computer, the formidable computations necessary for the use of integrated-rate equations are quite possible. The intention of this research was to develop the analytical and statistical methodology for applying an integrated-rate equation to a two-substrate reaction. I have analyzed the kinetics of pyruvate reduction, as catalyzed by the rabbit M4 isoenzyme of lactate dehydrogenase. Time courses were carried out, in sextuplicate, by observing the disappearance of NADH. Initial concentrations were: NADH, .026 to 1.7 mM; pyruvate, .016 to .29 mM; NAD+, 0 to 7 mM; and lactate, 0 to 40 mM. The concentrations of pyruvate and/or NAO+ were such that measurable enzyme inactivation did not occur. For each progress curve, values of Cf, Cs, C1, and C2 in the integrated equation were obtained by nonlinear regression; variances were calculated using replicate observations. Multiple regression, weighting each coefficient according to its variance, then gave 8 of the 11 J coefficients that characterize an ordered ternary-complex mechanism. The values obtained are comparable to previously published initial-rate values and predict progress curves that are consistent with the observed curves. The analysis required as few as nine experiments. A similar initial-rate study would require perhaps 10 times this number. This research shows that the computations necessary to apply progress curve methods can be routinely computerized; these methods are potentially a very powerful tool when used with the correct analytical techniques and experimental design.

The research object- the customs policy of the Republic of Lithuania. The research aim- to determine the changes in customs policy after Lithuania Joined EU. The objectives: 1) to research theoretical foundation of customs- to determine customs conception, functions, to estimate their significance and features of classification, to present the instrumentation of customs; 2) to do the analysis of Lithuania foreign trade and customs policy by joining the EU. 3) analize and evaluate the customs policy and overseas trade after Lithuania has become a EU member country. 4) anticipate the perspectives of customs policy implemented by Lithuania after joining the EU. Research methods- the analysis and synthesis of economical literature, logical abstraction, the methods of comparison, grouping and graphic modeling, interpretation and estimation of statistics. The scientific and economic literature, the regulation of the European community, also the law certificate of the Republic of Lithuania was explored in order to gain the main purpose. There were analyzed the reports of Foreign Office, the department of statistic, which is related to the government of the Republic of Lithuania next to the Board of exchequer. There were introduced the peculiarities of foreign customs and determined changes in trade treatment after joining the E.U.

The kinetics of drugs photodegradation have traditionally been treated using thermal kinetic analysis methods consisting most commonly in zero and first order kinetics. These treatment strategies were shown to lack specificity and present a number of limitations when applied to photoreactions kinetics. Nevertheless, these methods have widely been used due to a lack of integrated rate-laws for the majority of photoreactions types, in turn, due to the presence of a variable time-dependent factor in most photoreactions rate-laws that prevents their mathematical integration. To address these limitations, a new methodology for the development and validation of semi-empirical integrated rate-laws that faithfully describe photoreactions kinetics and photoreactions simulated cases generated by numerical integration methods (NIMs), is hereby presented. Using this methodology, a new kinetic order was ascribed to photoreactions namely the Φ-order kinetics. Semi-empirical integrated rate-laws were, thus, developed for three photoreaction types namely, unimolecular, AB(1Φ), photoreversible ,AB(2Φ), and consecutive, AB4(4Φ), photoreactions. The proposed models were further tested experimentally on drugs following these photodegradation mechanisms using; nifedipine and nisoldipine for unimolecular photoreactions; montelukast and fluvoxamine for photoreversible reactions; and riboflavin for consecutive photoreactions. The developed models not only accurately described the photoreaction kinetics of these drugs but also allowed the determination of all the kinetic parameters that characterise them. Furthermore, the above studied drugs were shown to act as precise and simple actinometers when analytically treated with the Φ-order kinetic methods, hereby presented. A universal standard method for the precise and worldwide reproducible study of drugs stability and compounds photoreactions, based on monochromatic irradiation and Φ-kinetics data analysis, is also detailed and adopted throughout the thesis. Finally, two new kinetic parameters namely, the pseudo-rate-constant and pseudo-initial velocity have been identified and shown to be more reliable and accurate in the description and universal comparison of photoreactions kinetics.