Distribution of newly described enterotoxin-like genes in Staphylococcus aureus from food

Extensive analysis of the Staphylococcus aureus genome has allowed the identification of new genes encoding enterotoxin-like superantigens (SEls). Some of these are thought to be involved in staphylococcal food poisoning, while others do not elicit any emetic effect. The potential impact of these members of the enterotoxin-like family on the human organism seems to rely mainly on their superantigenic activity. In this paper the distribution of the genes coding for enterotoxin-like superantigens in S. aureus isolated from food was studied. Fifty isolates of S. aureus were examined and 27 were shown to be enterotoxigenic. Only 9 of the 27 strains carried genes encoding enterotoxins SEA-SEE. In 18 SEA-SEE-negative strains the presence of newly described enterotoxin genes was detected. All SEA-SEE-positive strains simultaneously carried genes of new SEls. We show that the gene encoding SElH (staphylococcal enterotoxin-like enterotoxin H) was the most frequently detected (n=14), while genes encoding SElI together with SElG accompanied by the other genes of the egc locus were detected in three strains. We also detected the presence of three less investigated genes: sep, sel, and sek. These genes were present in eight, two, and one isolate, respectively. In one strain, sep was accompanied by genes of other SEls, while in the remaining seven it was the only enterotoxin-like gene detected. The high prevalence of newly discovered enterotoxin genes, including the genes encoding emetic toxins, was demonstrated in food-derived strains. This supports the need for additional work on its role in food poisoning and, alternatively, to monitor its presence in S. aureus isolated from food. Our results suggest that yet unknown genetic elements encoding enterotoxin genes may exist.     

Quantification of macrosegregation in continuously cast steel structures

Macrosegregation was investigated in longitudinal sections of continuously cast, experimental slabs of austenitic stainless steel and carbon-manganese steel. The macro-mapping technique was applied to investigate austenitic stainless steel slab sections. The method was based on electron probe microanalysis that was applied in a step-point mode to locally investigate segregation areas. The same stainless steel specimens and carbon-manganese steel specimens were etched to reveal the segregation structure. The macrosegregation in three carbon-manganese steel slabs was represented by etch-prints. The quantitative investigation of structure was performed directly on the macroetched specimens and on the etch-prints. The morphology of macrostructure was characterised by new parameters: segregation factor M, width of a segregation band W_0.5, centreline segregation intensity C and the heterogeneity index H. The segregation factor M was proportional to the inhomogeneity in segregate size distribution and to the segregate area fraction. W_0.5 was defined as the area where the segregate area fraction is greater or equal to half of the maximum value of measured area fractions. Parameter C equal to a ratio M_max/W_0.5, represented the intensity of centreline segregation. The heterogeneity index H was based on the measurements of mean size of segregates and the mean free path within segregate areas. For a homogeneous structure the heterogeneity index is zero and it increases with growing inhomogeneity of a macrostructure.     

Anodisches verhalten von chrom in wasserfreien und wasserhaltigen dimethylformamidH2SO4-und methanolH2SO4-Lösungen

The anodic film strongly inhibiting the dissolution of the chromium is formed on the surface of the metal in both the anhydrous and the water containing solution of sulphuric acid in organic solvents. The film results from the parallel solid-state reactions between the metal and sulphate ions, and between the metal and water. In the anhydrous solutions the amorphic salt film is formed. With the increase of the concentration of water the salt film changes into the salt-hydroxide film and at the end, at the highest water concentration, into the film of the hydroxide only. The critical concentration of water, for which the passive film reaches the hydroxide character, could be obtained from the relationship between the potential of passivity and the content of water in the solution.     

Self-Tuning Filter for Instrumentation

A microprocessor-controlled filter that tunes automatically to the fundamental of the input signal is described. Hardware and software implementation are shown, and the error in maximum amplitude selection is discussed. Filter performance using a switched capacitor tunable circuit is documented.     

Multiple regression analysis of Jominy hardenability data for boron treated steels

The relations between chemical composition and their hardenability of boron treated steels have been investigated using a multiple regression analysis method. A linear model of regression was chosen. The free boron content that is effective for the hardenability was calculated using a model proposed by Jansson. The regression analysis for 1261 steel heats provided equations that were statistically significant at the 95% level. All heats met the specification according to the nordic countries producers Classification. The Variation in chemical composition explained typically 80 to 90% of the Variation in the hardenability. In the regression analysis elements which did not significantly contribute to the calculated hardness according to the F test were eliminated. Carbon, silicon, manganese, phosphorus and chromium were of importance at all Jominy distances, nickel, vanadium, boron and nitrogen at distances above 6 mm. After the regression analysis it was demonstrated that very few outliers were present in the data set, i.e. data points outside four times the standard deviation. The model has successfully been used in industrial practice replacing some of the necessary Jominy tests.     

The effects of particle size, connective tissue and cooking regime upon properties of washed mechanically recovered broiler meat

Mechanically recovered meat (MRM) from broilers was washed with water, with or without prior chopping and with or without sieving to remove connective tissue. The resultant protein extract was mixed with salt and cooked in a one-step (directly to 80°C) or two-step (to 55°C and then to 80°C) cooking regime, to form gels. Washing broiler MRM gave stronger gels with lower cooking loss and expressible moisture than unwashed broiler MRM. These washed gels were also lighter in colour and less red. The best products were produced when some of the collagen had been removed by sieving, but not if the samples had Wrst been chopped, even though the total protein and dry matter contents were also reduced. A two-step cooking procedure enhanced gel strength. Evidence of a more porous, but dense, structure of washed broiler MRM subjected to a two-step cooking treatment was given by scanning electron microscopy and these differences could be related to the changes in gel strength and water holding.     

Matrix formulation of static analysis of cable structures

The paper concerns the static analysis of the cable structures. Energy approach is used in the analysis. Matrix formulation of the basic expressions for the total potential energy and its gradient is given. It is proposed in the paper to utilize the Huang's reverse algorithm for finding stationary point of the total potential energy. Enclosed is a numerical example.     

The effect of irradiation on technological properties and protein solubility of broiler chicken meat

During investigations on the effects of irradiation of chicken meat it was found that a 5 kGy dose of gamma ⁶⁰Co radiation brings about a statistically significant (P<0.05) increase in free water content, and fall in water holding capacity and water retention capacity, in breast muscles of broiler chickens. The cause of deterioration of hydration properties in meat is a decrease in solubility of the protein fractions after irradiation. The relative protein extractability Y (in 0.1M phosphate buffer+1.1M KI) fell in a linear manner with increase in the radiation dose D according to the equation Y=98.494–0.838 D. The changes in sarcoplasmic fraction extractability Y in 0.03M phosphate buffer are described by the equation Y=101.615–0.515 D, and those of myofibrillar fraction by Y=100.377–1.628 D. Electrophoresis of the protein fraction (soluble in phosphate buffer+1.1M KI) on polyacrylamide gel (with SDS) indicated that the lowest extractability, as compared with untreated samples, was shown by myosin. Other protein solubilities were only slightly altered by the 5 and 10 kGy doses.     

Hydraulic conductivity and pore sizes of nonwoven filter fabrics

This paper presents a method of determination of hydraulic conductivity and equivalent pore size of nonwoven synthetic filter fabrics. Piwowar's relationship for hydraulic conductivity, checked by Piwowar for glass and basalt fibres is given, and, on the basis of the transformation of Hagen-Poiseuille's formula, values of the empirical coefficients present in these formulae, the investigations on hydraulic conductivity and pore size of nine nonwoven filter fabrics were carried out. The numerical values of these coefficients and, after their substitution, the simplified formulae obtained for hydraulic conductivity and equivalent pore size of nonwoven synthetic filter fabrics are given.     

Preferential supporting of potassium carbonate around the peripheral region of activated carbon fibre

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.