A bondingness term is further developed to aid in heat of formation (ΔfHº) calculations for C, N, O and S containing molecules. Bondingness originated from qualitative investigations into the antibonding effect in the occupied MOs of ethane. Previous work used a single parameter for bondingness to calculate ΔfHº in an alkane homologous series using an additivity scheme. This work modifies the bondingness algorithm and uses the term to parameterise a test group of 345 molecules consisting of 17 subgroups that include alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. Comparing experimental with calculated ΔfHº values, a standard deviation for the residuals of 6.3 kJ mol 1 can be achieved using bondingness with a simple steric repulsion term (SSR) in a bond additivity scheme, and a standard deviation of 5.2 kJ mol 1 can be achieved using a Lennard-Jones potential. The method is compared with the group method of Pedley, which for a slightly smaller set of 338 molecules, a subset of the test set of 345 molecules, gives a standard deviation of 7.0 kJ mol 1. Bondingness, along with SSR or a Lennard-Jones potential, is parameterised in the lowest level of ab initio (HF-SCF) or semiempirical quantum chemical calculations. It therefore may be useful in determining the ΔfHº values for the largest molecules that are amenable to quantum chemical calculation. As part of our analysis we calculated the difference between the lowest energy conformer and the average energy of a mixture populated with higher energy conformers. This is the difference between the experimental ΔfHº value and the ΔfHº calculated for a single conformer. Example calculations which we have followed are given by Dale and Eliel et al.. Dale calculates the energy difference for molecules as large as hexane using relative energies based on the number of 1,4 gauche interactions. We have updated these values with constant increments ascertained by Klauda et al. as well as ab initio MP2 cc-pVDZ relative energies and have included calculations for heptane and octane.

Masonry walls are usually laid with the individual masonry units along a course overlapping units in the course below. Commonly, the perpend joints in the course occur above the mid-points of the units below to form a ‘half-bond’ or above a third point to form a ‘third-bond’. The amount of this overlap has a profound influence on the strength of a wall supported on three or four sides, where lateral pressures from wind cause combined vertical and horizontal flexure. Where masonry units are laid with mortar joints, the torsional shear bond resistance between the mortar and overlapping units largely determines the horizontal flexural strength. If there is zero bond strength between units, then the horizontal flexural strength is derived from the frictional resistance to torsion on the overlapping bed-faces of the units. This thesis reports a theoretical and experimental investigation into the frictional properties of overlapping units when subjected to combinations of vertical and horizontal moments and vertical axial compression. These basic properties were used to develop a theory to predict the lateral strength of walls supported on two, three or four sides. A plastic theory of behaviour was confirmed by experiment. The theory was then used to determine maximum unbraced panel sizes for particular boundary conditions. Design charts were developed to determine temporary bracing requirements for panels during construction.

In marine environments and where de-icing salts are applied, the degradation of reinforced concrete structures due to chloride induced corrosion of the reinforcement is a major problem. The expansive nature of the corrosion process results in cracking of the concrete and eventually spalling. In order to select suitable remedial measures it is necessary to make an assessment of the residual strength and the residual life. In order to investigate the effect of corrosion on bond strength of the reinforcement, specimens comprising square prismatic sections containing steel reinforcement in the four corners have been subjected to a wet-dry cycle and corrosion has been accelerated by polarising the bars. The research has studied the change of bond strength with level of corrosion for 12 mm and 16 mm bars with concrete cover of 1 and 3 times the bar size. The bond strength is assessed by means of pull out tests and the corresponding extent of corrosion has been assessed in terms of the mass loss. Observations and measurements of the form of the corrosion (pit dimensions and loss of bar diameter) are also presented. The relationship between bond strength and surface crack width has been investigated. Results show that the surface crack width may be a good indicator of residual bond strength. In addition, the influence on bond strength of concrete compressive strength, reinforcement cover, bar position and bar size on the change of bond strength has been explored. It should be noted that all conclusions drawn in this project are based on tests on specimens without shear reinforcement (unconfined) and that accelerated corrosion (by impressed current) has been adopted. Consequently, care should be exercised in applying these results directly to structures in the field. Additional research is needed to assess the influence of impressed current on crack patterns and the effect of shear reinforcement.

No description available.

<p>Peptide bond formation and translational termination on the ribosome have been simulated by molecular mechanics, free energy perturbation, empirical valence bond (MD/FEP/EVB) and automated docking methods. Recent X-ray crystallographic data is used here to calculate the entire free energy surface for the system complete with substrates, ribosomal groups, solvent molecules and ions. A reaction mechanism for peptide bond formation emerges that is found to be catalyzed by the ribosome, in agreement with kinetic data and activation entropy measurements. The results show a water mediated network of hydrogen bonds, capable of reducing the reorganization energy during peptidyl transfer. The predicted hydrogen bonds and the structure of the active site were later confirmed by new X-ray structures with proper transition states analogs. </p><p>Elongation termination on the ribosome is triggered by binding of a release factor (RF) protein followed by rapid release of the nascent peptide. The structure of the RF, bound to the ribosomal peptidyl transfer center (PTC), has not been resolved in atomic detail. Nor is the mechanism known, by which the hydrolysis proceeds. Using automated docking of a hepta-peptide RF fragment, containing the highly conserved GGQ motif, we identified a conformation capable of catalyzing peptide hydrolysis. The MD/FEP/EVB calculations also reproduce the slow spontaneous release when RF is absent, and rationalize available mutational data. The network of hydrogen bonds, the active site structure, and the reaction mechanism are found to be very similar for both peptidyl transfer and termination. </p><p>New structural data, placing a ribosomal protein (L27) in the PTC, motivated additional MD/FEP/EVB simulations to determine the effect of this protein on peptidyl transfer. The simulations predict that the protein N terminus interacts with the A-site substrate in a way that promotes binding. The catalytic effect of L27 in the ribosome, however, is shown to be marginal and it therefore seems valid to view the PTC as a ribozyme. Simulations with the model substrate puromycin (Pmn) predicts that protonation of the N terminus can reduce the rate of peptidyl transfer. This could explain the different pH-rate profiles measured for Pmn, compared to other substrates.</p>

Peptide bond formation and translational termination on the ribosome have been simulated by molecular mechanics, free energy perturbation, empirical valence bond (MD/FEP/EVB) and automated docking methods. Recent X-ray crystallographic data is used here to calculate the entire free energy surface for the system complete with substrates, ribosomal groups, solvent molecules and ions. A reaction mechanism for peptide bond formation emerges that is found to be catalyzed by the ribosome, in agreement with kinetic data and activation entropy measurements. The results show a water mediated network of hydrogen bonds, capable of reducing the reorganization energy during peptidyl transfer. The predicted hydrogen bonds and the structure of the active site were later confirmed by new X-ray structures with proper transition states analogs. Elongation termination on the ribosome is triggered by binding of a release factor (RF) protein followed by rapid release of the nascent peptide. The structure of the RF, bound to the ribosomal peptidyl transfer center (PTC), has not been resolved in atomic detail. Nor is the mechanism known, by which the hydrolysis proceeds. Using automated docking of a hepta-peptide RF fragment, containing the highly conserved GGQ motif, we identified a conformation capable of catalyzing peptide hydrolysis. The MD/FEP/EVB calculations also reproduce the slow spontaneous release when RF is absent, and rationalize available mutational data. The network of hydrogen bonds, the active site structure, and the reaction mechanism are found to be very similar for both peptidyl transfer and termination. New structural data, placing a ribosomal protein (L27) in the PTC, motivated additional MD/FEP/EVB simulations to determine the effect of this protein on peptidyl transfer. The simulations predict that the protein N terminus interacts with the A-site substrate in a way that promotes binding. The catalytic effect of L27 in the ribosome, however, is shown to be marginal and it therefore seems valid to view the PTC as a ribozyme. Simulations with the model substrate puromycin (Pmn) predicts that protonation of the N terminus can reduce the rate of peptidyl transfer. This could explain the different pH-rate profiles measured for Pmn, compared to other substrates.

The focus of the proposed research will be on exploring the use of nanotechnology-based nano-filaments, such as carbon nanotubes (CNTs) and nanofibers (CNFs), as reinforcement in improving the mechanical properties of portland cement paste as a construction material. Due to their ultra-high strength and very high aspect ratios, CNTs and CNFs have been used as excellent reinforcements in enhancing the physical and mechanical properties of polymer, metallic, and ceramic composites. Very little attention has been devoted on exploring the use of nano-filaments in the transportation industry. Therefore, this study aims to bridge the gap between nano-filaments and transportation materials. This will be achieved by testing the integration of CNTs and CNFs in ordinary portland cement paste through state-of-the-art techniques. Different mixes in fixed proportions (e.g. water-to-cement ratio, air content, admixtures) along with varying concentrations of CNTs or CNFs will be prepared. Different techniques commonly used for other materials (like polymers) will be used in achieving uniform dispersion of nano-filaments in the cement paste matrix and strong nano-filaments/cement bonding. Small-scale specimens will be prepared for mechanical testing in order to measure the modified mechanical properties as a function of nano-filaments concentration, type, and distribution. With 0.1 percent CNFs, the ultimate strain capacity increased by 142 percent, the flexural strength increased by 79 percent, and the fracture toughness increased by 242 percent. Furthermore, a scanning electron microscope (SEM) is used to discern the difference between crack bridging and fiber pullout. Test results show that the strength, ductility, and fracture toughness can be improved with the addition of low concentrations of either CNTs or CNFs.

In the past, the Swedish bond market has been distinguished for its illiquidity and difficulties with retrieving information. This is the starting point of our thesis and the purpose is to analyze and describe the availability of the present corporate bond market for manufacturing firms in Sweden. In order to fulfill the purpose, a qualitative method was used and interviews with different operators of the market were conducted. Our respondents were sampled from large issuing companies, the major intermediaries and companies that have not tried bonds as a financing tool. To fulfill our purpose, we analyzed subjects as credit rating, capital market segmentation, regulations and volume. We came to the conclusion that the Swedish corporate bond market is somewhat underdeveloped. This is due to the lack of public information regarding the bonds, such as prices, outstanding bonds and interest rates. The availability for already active companies is good, mainly due to the important role the intermediaries play. The regulations set by authorities do not have great effect on the large companies in general, since they issue large amounts, the cost associated with the regulations do not affect them in a considerable way. One could rather see a positive side with the regulations, for example the increase of foreign issuers that entered the market the last couple of years and hence increasing the liquidity. A credit rating is sometimes beneficial but not always, it is not a necessity to enter the bond market. As a matter of fact, it seems like volume is the most important reason to why medium-sized companies have limited access to the market. Since the minimum recommended volume to issue is 50 million SEK, many companies are excluded due to lack of financing need. Another important factor concerning medium-sized companies is that they do not have sufficient experience, knowledge or interest in the bond market. There are probably companies that would like to enter the bond market, who do not have the opportunity to do so, but this do not have anything to do with the lack of credit rating, rather the high cost associated with it. The conclusion drawn is that it is hard to compare small and medium-sized companies with large already established actors. This is due to different need of capital and overall knowledge about the debt market.

I Sverige finns drygt en miljon hundar, vilket ger siffran en hund i vart femte hushåll. Främsta syftet med föreliggande studie är att se vad som är den positivt verksamma kärnan i umgänget mellan människa och hund, utifrån vad hundägare subjektivt berättar. Enligt Grounded Theory analyserades sex djupintervjuer. Resultaten visar framförallt en Personlig vinst för den enskilde hundägaren i umgänget med sin hund. Den Personliga vinsten består av de sex delvinsterna Säkerhet, Kamratskap, Kunskap, Aktivitet, Socialt och Hälsa. En slutsats är att hunden påverkar hundägaren på ett positivt sätt, eftersom den ger en personlig vinst i form av tillfredsställelse av många av människans grundläggande behov.

Eighteen splice specimens were tested under four-point loading as part of a larger experimental investigation to study the behaviour of lap spliced plain steel bars in reinforced concrete specimens. Three of the specimens were instrumented with strain gauges adhered to the reinforcement and the concrete side face. Three lap splice lengths, two bar sizes for square bars, and one bar size for round bars were investigated. The principal reinforcement was either cast in the bottom or top position. The results of maximum loads, crack patterns, load versus deflection behaviour, and deflected profiles are presented for all specimens. The analysis of specimens with strain gauge instrumentation is also presented, and includes results of strain compatibility, bond stress distribution, and flexural section analysis. All specimens failed by bond, caused by a sudden pullout of the reinforcement within the splice region. An equivalent round diameter based upon the cross-section area of the square bars allowed for a single predictive equation between the maximum normalized load as a function of splice length, casting position and bar size. A top cast factor of 0.4 and 0.6 captures the reduction in the maximum normalized load for specimens cast with round and square bars, respectively, in the top position. The CEB-FIP Model Code (1993) predictive equations are reasonably conservative in capturing the behaviour of specimens reinforced with round bars cast in the bottom position, and square bars with side dimension of 25 mm cast in the bottom position. However, the CEB-FIP Model Code (1993) predictive equation is unconservative when predicting the behaviour of specimens reinforced with either square or round bars cast in the top position. On the other hand, the draft CEB-FIP Model Code (2010) provisions showed an overly conservative prediction for all specimens reinforced with either round or square bars cast in the top or bottom position. Instrumented specimens showed that strain compatibility between the longitudinal reinforcement and the surrounding concrete did not exist for much of the loading range due to bond loss. The evaluation of the neutral axis location within the shear span showed that shear is first transferred by beam action, followed by arch action. The use of three strain gauges adhered to the concrete side face provided flexural moments similar to that predicted theoretically.