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Bitumen membranes have a primarily waterproofing function in the construction industry. The waterproofing function in bitumen membranes is provided by the mas of bitumen. The amount of bitumen mass can be determined by various methods. This paper deals with the determination of the bitumen mass in bitumen membranes by means of extraction and calcination. In the current legislation, the quantity of bitumen mass can only be determined by extraction. The calcination method is specified in the forthcoming EN 544, which is used for bitumen shingles. Previous research by the author has shown that the methodology from this standard cannot be used. The aim of this paper is to provide a practical verification of the extraction and calcination methods from previous author's research on a set of selected bitumen membranes. A total of 6 bitumen membranes were used for comparison. The bitumen membranes were of the same type from different manufacturers. The bitumen membranes were extracted in xylene. Calcination was carried out at 600°C. Two claims were made that confirmed the results of previous research on the bitumen coating and bitumen membranes. The first claim was that the calcination method is as time consuming or faster. This claim was confirmed. The second claim was that the results between extraction and calcination would differ by a maximum of 1.3%. The second claim was only partially met because the two asphalt strips contained insoluble but burnable parts. The results therefore differed by more than 1,3 %. [ABSTRACT FROM AUTHOR]

Enzyme synthesis of tryptophan from indole, pyruvate and ammonium salts was studied using Escherichia coli cells exhibiting a significant tryptophanase activity. In addition to the effect of cultivation medium composition and cultivation conditions, factors affecting the course of the conversion were investigated. Production of 32.4 g/L of l-tryptophan was reached after 48 h under optimal conditions. [ABSTRACT FROM AUTHOR]

A mutant Corynebacterium sp. requiring threonine and cultivated for 3 d in a medium containing 15 % sucrose, 8 % corn-steep and 50 µg biotin per litre accumulated 14.5 g-homo-serine per litre. The possibility of fermenting the homoserine obtained for threonine and lysine production was investigated. [ABSTRACT FROM AUTHOR]

The production of L-lysine from DL-α-amino-ε-caprolactam ( DL-ACL) by new strains producing L-α-amino-ε-caprolactamase and aminocaprolactam racemase is described. Optimal conditions for hydrolysis of L-ACL by Cryptococcus sp. and for racemization of ACL by cells of a strain isolated in nature and identified as Pseudomonas sp. were determined. Synthesis of L-α-amino-ε-caprolactamase is induced by DL-ACL or L-lysine with the same effectivity. A positive effect of phosphates (potassium salts) on reduction of the induction lag was detected, the synthesis of this enzyme was found to be repressed by glucose and some possibilities of the reversion of this repressive effect were demonstrated. Under conditions optimal for the production of both enzymes a quantitative theoretical conversion of 10 % aqueous DL-ACL to L-lysine by a mixture of native cells in a mass ratio of 1: 2 (producer of ACL-hydrolase to producer of ACL-racemase) occurred in 8 h at 40 °C and pH 8.0 [ABSTRACT FROM AUTHOR]

Production of L-lysine was followed in two lysine-accumulating mutants of Corynebacterium glutamicum ATCC 13287 in media containing sucrose, ethanol, acetic acid or a mixture of acetic acid and ammonium or sodium acetate. It was found that acetate is the best substitution for sucrose. [ABSTRACT FROM AUTHOR]

After a 4-d cultivation in a medium containing 7.5 % glucose, 0.6 % ammonium nitrate and 0.5 % peptone, the leaky mutant Corynebacterium sp. 9366-EMS/270 stimulated in its growth by argiuine, was found to accumulate 12.2 g dl-alanine per litre medium. [ABSTRACT FROM AUTHOR]

Among 23 microbial strains, Alcaligenes metalcaligenes CCEB 312 was found to be most suitable for the conversion of fumaric acid to l-aspartic acid. In a growth medium containing 4% peptone, the strain produced as much as 50 g l-aspartic acid per litre. [ABSTRACT FROM AUTHOR]

The auxotrophic mutant Corynebacterium 9366-EMS/184, requiring isoleuoine accumulates about 22 g of L-valine per litre after a 96 h cultivation in a medium containing 15% sucrose and 1% ammonium acetate. [ABSTRACT FROM AUTHOR]

This paper deals with the surface temperature problem of flat roofs, where bitumen sheets are used as the final waterproofing layer. Currently it is possible to find defects due to the high surface temperature of the waterproofing layer on flat roofs. The result of such a high surface temperature is, for example, the release of bitumen sheets and the sublimation of the thermal insulation from foamed polystyrene. The paper focuses on the influence of the type, the color of the sprinkling and the type of background on the surface temperature. The aim of this paper is to determine the surface temperature of bitumen sheets based on the experimental measurement depending on the type and the colour of the surface. Measurements were made during warm summer days. Samples of bitumen sheets with green, grey, blue-grey, red, white and black-grey sprinkling were used. Concrete and foamed polystyrene were used as a background under bitumen sheets.

This paper follows up on the results of a research presented at the conference Building Defects 2017. The paper deals with the dimensional stability of bitumen sheets. The manifestation of insufficient dimensional stability is the shrinkage of bitumen sheets in the transverse joints. Shrinkage of bitumen sheets with reinforced polyester liner and a non-reinforced glass fiber is primarily due to insufficient technological discipline. The paper deals with the influence of melting of the sheet on its possible shrinkage during roof exposure. Previous research has shown that the shrinkage happening during melting accounts for more than 50 % of the total shrinkage. The aim of this paper is to show the size of the effect on the biasing of the load-bearing insert during the realization of the waterproofing layer in bitumen sheets with a glass-reinforced polyester carrier liner. The experiment, expressed by the dimensional stability test according to ČSN EN 1107, was performed in a laboratory on three samples of bitumen sheets. Bitumen sheets had different types of reinforcement and a different weight of the carrier liner.

This article focuses on the frequently discussed topic how to make the frontal joints of bitumen sheets with coarse-grained surface coating. Bitumen sheets have a spill in the place of these joints. Insufficient strength of the frontal joint is one of the possible faults in waterproofing using bitumen sheets. The paper compares different ways of performing these joints in terms of force stress based on surface treatment. Surface treatment is possible by immersing the sprinkle, scraping it into the bitumen sheet mass, or simply heating the surface and leaving it unpainted.

One of the frequent sources of flat roof faults is failure of the top layer of a multilayer bitumen sheet system in cross-connections. One of the possible causes of this disorder is failure to observe technological discipline. The paper deals with how the full melting of the bitumen sheet influences its possible shrinkage during the roof exposure. Bitumen sheets with a polyester carrier which is not reinforced with fiberglass fibers are burdened with shrinkage effect. The preload is introduced into these belts during production. The aim is to show how is the effect on loosening the preload in the carrier layer with full-scale smelting during the realization of the waterproofing layer. The preload loosening experiment, expressed by the dimensional stability test according to ČSN EN 1107, was performed in a laboratory on two bitumen sheets.

Fermentative preparation of l-alanine by Streptomyces coelicolor 3-19 was developed under laboratory conditions. In a medium containing glucose, corn-steep and mineral salts, the strain accumulated 9 g l-alanine per litre after four days of cultivation. [ABSTRACT FROM AUTHOR]

The strain Corynebacterium sp. 9366-H-454 grown on medium containing 10% sucrose and 4% corn-steep was found to produce as much as three times or four times (under laboratory conditions and on a pilot plant scale, respectively) more lysine than on the original. H-medium. The values are economical for a fermentation preparation of lysine. [ABSTRACT FROM AUTHOR]