No description available.

No description available.

M. S.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Although Eucalyptus species are indigenous to Australia, they have been successfully cultivated in South Africa, where they are mainly used in the mining and paper industries. With the explosion in these industries it has been necessary to increase Eucalyptus plantations, often into areas which experience frost and chilling temperatures. To combat this, high yielding Eucalyptus species able to cope with these conditions would be desirable. The ability to rank species according to their chilling tolerance will enhance decisions as to the suitability of species for use in the field. To this aim, two biochemical and two biophysical parameters were chosen to investigate and characterise Eucalyptus nitens, E. smithii, E. macarthurii, E. grandis and E. grandis x nitens (GNI026). Ranking of these species in terms of chilling tolerance did not appear possible using the data from the biochemical parameters (proline concentration and glutathione reductase activity), but the biophysical parameters (fluorescence characteristics and onset of temperature of melt) gave results comparable to those obtained in field trials using these species. Fluorescence characteristics were particularly useful in assessing the chilling tolerance of the species in question. Fluorescence is the recommended technique for further studies as it is relatively inexpensive, rapid, does not require destructive sampling and can be used in both the laboratory and field. / Thesis (M.Sc.)-University of Natal, 1993.

Lime mortar and plaster have been investigated with the aim to improve the knowledge on how to make them as durable as before the cement technology was developed. The background was the durability problems experienced for newly produced lime plaster on the medieval churches on the island of Gotland, Sweden. In some cases the new lime plaster façades showed severe frost damages after only one winter. Although the lime was burnt and produced according to old local traditions, the lime mortar was still mixed and worked onaccording to methods developed for lime-cement mortar. This often led to a very porous lime plaster with a lime shell in the surface and such a plaster has been shown to be sensitive to frost expansion. Field studies were combined with laboratory studies of thin section specimens. Optical microscopy and scanning electron microscopy have been important analytical methods showing the porosity and the structure of the binder and aggregate materials. The investigations have been carried out on both historic and on newly made reference mortar and plaster. The field studies were carried out mainly on Gotland, using local materials. The influence of the raw materials, i.e. lime, aggregate and blending ratio was investigated. The focus has been on the workability of the fresh mortars as well as the pore structure of the carbonated plaster. The craftsmanship, meaning mixing and application of mortar and working the plaster surface, was studied in order to clarify its final pore structure. The pore structure in a material determines many of its technical properties, such as moisture transportation, compressive strength, permeability and frost resistance. All these properties are closely connected to the durability of the mortar and plaster. The permeability of the plaster has an impact also on the durability of the covered construction materials. Behind low-permeable plasters made with hydraulic binder, examples of extensive damages of rotten wood and leached lime have been shown. The investigations have shown the importance of choosing a mortar adjusted to the building construction. They also showed the importance of choosing a blending ratio adjusted to the specific binder and sand used in order to get a mortar with a suitable pore structure and good durability. It has also shown the importance of knowing when and how to work on the plaster surface in order to obtain a homogenous material that is well receptive for lime wash and has a good frost resistance. The combination of all the investigations has led to a method for reconstructing historic mortar and plaster with good durability.

Master‘s thesis “Substitution of silica filler in the repair mortars by artifical compact material“ could by generally divided into two parts theoretical and experimental. The theoretical part is mainly focused on summarizing knowledge about repair mortars. The repair mortars are used for reprofilation of disrupted concrete layers, and therefore some of the most common defects of these layers, from which we can determine requirements for repair mortars are listed in the thesis. In the theoretical part, there is also mentioned a general formula of how to prepare a repair mortar, also there are described manufacture and characteristics of the most important ingredients of mortars such as cement, filler (aggregate), water and chemical modificators. Above all the theoretical part is focused on the effects that individual ingredients have on the resulting properties of repair mortars. The experimental part could be further divided into two parts. In the first part there are listed properties of the individual investigated materials and also there is introduced theoretical basis for particular tests of properties of repair mortars, such as analysis of grading distribution of a filler (aggragate), tests of flexular and compression strengths and frost resistance. In the first part there are also proposed formulae of mortar mixtures, where part of the original filler was substituted by an abrasive material TRYMAT, artificial compact aggregate made from blast furnace slag UHK d/D, or their combination. The properties of these mortar mixtures were compared to referential mortar mixture PANBEX R1. In the second part of experimental section is dedicated to summarization and discussion of the obtained results for individual mortar mixtures.

This thesis, which comprises of a theoretical and a practical part, deals with possible means of increasing ceramic body frost resistance. The current state of research in the field of ceramic body frost resistance is summarized in the theoretical part. The practical part is divided into two sections. In the first section, the influence of firing temperature (820 °C and 1020 °C) and duration (2, 4 and 6 hours) on frost resistance and several other parameters is assessed by means of experiment, using a specimen of brick body made of mixes currently used in roof tile production by TONDACH Šlapanice and TONDACH Dolní Jirčany factories. In the second section of the practical part, two modifications are introduced of the mixture currently used in roof tile production in the TONDACH Šlapanice factory – GE clay and zeolite supplements were added, the effects of which are verified by means of experiment using specimens fired in a kiln designated for ceramic masonry blocks and alternatively in a kiln used for firing TONDACH Šlapanice roof tiles.

No description available.

<p>This is a genetic study of flowering time in cultivated barley with the aim to identify the alleles contributing to rapid flowering and frost resistance. We have genotyped a collection of 23 historic barley varieties for the crucial genes [<em>VRN-1, VRN-2, VRN-3</em> (<em>HvFT</em>), <em>Ppd-H1, CO</em>, and <em>Vrs1</em>]. We have amplified the polymorphic mutations by PCR-based methods, and sequenced them to identify possible haplotype groups. The row type was not determined of all accessions, but all the Scandinavian varieties were found to carry mutant alleles of <em>Vrs1</em>, that indicates them to be six-row barleys. The deletion of the crucial segment of <em>VRN-1 </em>vernalization contributes dominant spring growth habit. We found haplotype groups 2 and 4 to be dominant in Northern barleys whereas haplotype groups 1 and 5 dominated in south. The presence of dominant allele <em>VRN-2</em> gene is addressed to floral repression until plants get vernalized. Most of the 23 varieties were found to have deleted allele of <em>VRN-2</em>, which is connected with a spring growth habit. The only four of the accessions that have the dominant allele of <em>Ppd-H1</em> that contribute flowering are generally from the south of Europe. <em>HvFT</em> and <em>CO</em> genes <em>CO</em>-interact to influence flowering time. <em>CO</em> haplotype grouping suggest a geographical distribution of different alleles but needs more disseminations. Certain <em>HvFT</em> alleles cause extremely early flowering during apex development in the varieties that have deletion of <em>VRN-2</em> alleles under long days. <em>VRN-3</em> alleles of 14 varieties were identified.</p>