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Thermal analysis of some fly ashes

II. Self-hardening activity of fly ashes

Authors: Z. Adonyi and K. Mészáros Szécsényi

The self-hardening activity of fly ashes was investigated looking for the possibility of their chemical reactions with water without additives. A method had to be developed for separation of the structural water from the adsorbed or free one. The decomposition of the chemically bound water was measured by thermogravimetry. The‘I’ dimensionless number proved to be applicable for the quantitative characterisation of the measured data with more DTG peaks. The examined reaction depends on the chemical composition and the physical structure of the fly ashes and the time of interaction with water. The SO3 content seems important, but the characteristics of the formed compounds differ deeply from the CaSO4·2H2O. The observed and examined reaction is an important factor of the self-hardening process of fly ash deposits.

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Shell eggs have been irradiated with increasing radiation doses in the 0.5-3.0 kGy dose range and various non-microbiological changes, important from the point of view of consumer quality, have been estimated. Dose-dependent changes in the flow behaviour of egg white and brittleness of the yolk membrane in broken eggs, sensorial parameters of the raw and soft-boiled eggs, whippability and foam stability of the egg white were observed. Considering that a minimal dose of 1.5 kGy would be required for radiation inactivation of salmonellae and other, non-pathogenic bacteria, the quality of irradiated eggs upon such gamma radiation dose would not be equal in all parameters to those of the fresh shell eggs, however, changes in sensorial and functional properties at this dose level may be still acceptable, mainly for risk population and some industrial use.

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Abstract  

A method is described for the microdistillation of liquids using quasi-isothermal quasi-isobaric thermogravimetry. The liquidus curve determined under quasi-equilibrium conditions gives useful information about the composition and some thermal properties of the sample. The method could be attractive for the mineral oil, lacquer, biological and organochemical industry.

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Authors: Zs. Mészáros, K. Kiss, M. Szmodis, M. Zsidegh, M. Mavroudes and János Mészáros

The aim of the present longitudinal study of four years was to analyse differences in growth patterns, age-related changes in body fat and physical performance in schoolchildren taking part either in normal or in elevated level physical education at school.Nine data collection sessions were carried out between 2002 and 2006 in 18 schools. The sample consisted of 521 non-athletic volunteer boys (PE=116, contrast = 405).The inter-group differences between mean height, body weight, body mass index, relative body fat content, mean scores in 30 m dash, 400 m run, and standing long jump as well as the patterns of change with age were analysed in this comparison. Between-observation differences were tested by repeated measures ANOVA. In case of a significant F-test Tukey’s post-hoc tests were used. Age dependence was also studied by linear regression analysis.The between-group differences in mean height were not significant, but the slope of height increase with age was significantly greater in the PE boys. The PE boys were significantly lighter through all the nine observations and the slope of age-related weight increase was statistically faster in the group of contrast subjects. Both the BMI means and percent body fat means were consistently and significantly greater in the contrast group and faster increases were found in the group of the less active boys. The mean physical performances of the PE boys were consistently and significantly better. Their slopes of increase were statistically different.

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Authors: Á. Sziva, Zs. Mészáros, K. Kiss, M. Mavroudes, N. Ng and János Mészáros

Long-range repeated-measure sample differences in body dimensions, body composition and physical performance help to describe the changes in a population’s lifestyle. The aim of our study was to analyse such changes in longitudinal studies repeated after a 25-year interval. Data collections repeated every six months for the periods 1977–1981 (n=152) and 2002–2006 (n=158) were carried out in nonathletic boys aged between 6.51 and 11.50 years from the same districts of Budapest. Means for height, body mass, BMI, body fat percentage, and distance covered during a running endurance test, as well as the slopes of the changes were compared. The children of the second series of studies were significantly taller and heavier, had more depot fat and showed poorer cardio-respiratory endurance than their peers 25 years before. The increases with age in weight, BMI and depot fat were steeper in the second series. The significant differences that developed in anthropometric traits and physical performance during these 25 years are regarded as indirect evidence for how severely the average physical condition had declined, as well as how health risks of the schoolchildren had increased.

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Authors: K. Kiss, Zs Mészáros, M. Mavroudes, M. Szmodis, M. Zsidegh, N. Ng and János Mészáros

The aim of this comparison was to evaluate the nutritional status and cardio-respiratory fitness of future health professionals, namely university students engaged in medical studies. It was assumed that the lifestyle of such students would be reflected by healthy body composition and fitness performance indicators. Altogether 1,560 volunteer, female, university students of three institutions were investigated in 2008. Height, body weight, BMI, body fat content and 800 m run test means were compared.The height, weight and BMI means did not differ significantly but PE students recorded the lowest mean body fat (18.34% vs. 24.37 and 25.12%) and shortest mean running time (203 s vs. 239 and 243 s). Among the medical (11.23%) and technical university students (19.95%) statistically the same prevalence of obesity was observed.High body fat content and low running performance of medical students were in contrast with our hypothesis. Their prevalence of overweight/obesity and low fitness did not differ from that of relatively sedentary technical university students and the average Hungarian young adult population. Thus, it is questionable how young health professionals will promote the necessity and positive effects of regular physical activity if they do not apply them to their own lifestyle.

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Authors: P. Osváth, Zs Mészáros, Sz Tóth, K. Kiss, M. Mavroudes, N. Ng and János Mészáros

Fatness generally has a negative influence on the performance of a variety of motor and cardiorespiratory fitness tests. The aim of this comparison was to analyse the effects of three grades of obesity on somatic growth, physical performance and oxygen consumption during exercise. Volunteer boys with definitely different grades of obesity were recruited for the comparison. In the group of mildly obese children (G1; n=23) BMI ranged between 24 kg.m −2 and 26 kg.m −2 ; and individual percent body fat was between 33% and 33.5%. In the case of moderate obesity (G2; n=23) BMI ranged between 26.5 kg.m −2 and 28.5 kg.m −2 ; and percent body fat was between 35% and 36%. In the extremely obese group (G3; n=20) BMI was greater than 31 kg.m −2 ; percent body fat was greater than 37.5%. Oxygen consumption during the 1,200 m run-test was measured by VIMEX-ST-type (USA) telemetric equipment.The greatest absolute aerobic power referred to the G3 boys, and the lowest oxygen consumption was characteristic of the mildly obese group. The very high differences between the body mass means resulted in a more marked inter-group variability in mean relative oxygen uptake.The predicted relative fat and high body fat content observed on the trunk, and the elevated level of resting blood pressure may indicate serious risks for the development of cardio-respiratory and metabolic disease. The very low oxygen consumption relative to body mass and poor physical performance are expected consequences of physiologic and environmental influences on the obese population.

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The effect of explant type (immature vs. mature embryos) and two auxin types (2,4-dichlorophenoxyacetic acid vs. Dicamba) on the callogenesis and plant regeneration ability of 26 wheat cultivars was studied. In general, the callus induction, plant regeneration and shoot formation frequencies were higher in mature embryo-derived cultures as compared to immature ones on media originally developed for mature wheat embryo cultures. In both culture types, the auxin Dicamba was found to be more efficient, especially when mature embryos were cultured. The separation of means using Duncan’s multiple range test revealed the best in vitro response, in terms of the frequency of callus regeneration, in the cultivar Astella for both immature and mature embryo cultures. This cultivar gave very promising results, suggesting that it could be used in the future for further tissue culture investigations and as a donor material for genetic transformation experiments in wheat. Correlation analyses revealed significant similarities between the evaluated parameters within each group (immature and mature embryo-derived cultures). However, there were no significant correlations between these two groups for most of the parameters. This suggests that the mechanism of plant regeneration in the two in vitro regeneration systems (mature vs. immature embryo culture) may be different enough to hamper the development of an optimal plant regeneration protocol for use in both systems.

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An efficient regeneration system is described based on the use of several genotypes and combining different cytokinins in the regeneration process. Optimal regeneration efficiency can be obtained if the factors affecting regeneration are examined with special attention to the maintenance of the stock plants, the composition of the medium, and the pre-treatment. The maintenance of stock plants proved to be optimal if the plants were kept on modified LS medium supplemented with 0.125 mg L −1 6-benzylaminopurine (BAP) and 0.01 mg L −1 indole-3-butyric acid (IBA) in large vessels. Pre-treatment was found to increase the regeneration efficiency. Placing the leaves on to medium containing 1.5 mg L −1 BAP-riboside and 0.1 mg L −1 thidiazuron (TDZ) without wounding, and keeping them in the dark for 6 days gave the best results. The highest regeneration rate was observed on medium containing MS salts with B5 vitamins complemented with 20 g L −1 glucose, 3 mg L −1 BAP-riboside, 0.2 mg L −1 TDZ and 0.2 mg L −1 IBA. This system made it possible to achieve regeneration in each of the varieties examined, though to different extents.

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In order to evaluate the effect of light intensity and photoperiod on heading and to establish the reaction types of barley, a set of barley germplasm of various geographical origin and growth habit was examined in a series of controlled growth chamber experiments combining two levels of light intensity with long and short photoperiod regimes. Low light intensity contributed only a limited portion to the total variance of heading and this originated to a large extent from the genotype × light intensity interaction for both photoperiods. Under the long photoperiod regime the effect of low light intensity was only apparent in a significant delay in heading. Under a short photoperiod the type of sensitivity depended on the growth habit. Low light intensity hastened plant development in 15% of the spring barley varieties, while the flowering of 44% of the winter barley varieties was significantly delayed. Establishing the reaction types for photoperiod and low light intensity in this range of barley germplasm made it possible to identify the typical reaction types of the two growth-habit groups. In addition, it also became possible to identify genotypes with contrasting or unusual combinations of these traits.

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