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排序方式: 共有45条查询结果,搜索用时 703 毫秒
1.
Leptin is a hormone that coordinates food intake, energy expenditure, and metabolic rate; it is, however, unknown how exercise influences plasma leptin concentration in horses. The aim of the study was to evaluate the exercise-induced changes in plasma leptin concentration in purebred Arabian horses competing in races and endurance rides. A total number of 26 horses (12 purebred Arabian racehorses aged 3–5 years and 14 endurance horses aged 7–14 years) were studied during performing routine physical exercise. From each horse, blood samples were collected at rest and immediately after the exercise session. Concentrations of plasma leptin, cortisol, lactic acid, uric acid, triacylglycerols, glycerol and free fatty acids were determined. Exercise-induced increase in cortisol and free fatty acid values were higher in endurance horses than in racehorses. Neither endurance nor race exercises influenced the plasma leptin concentration. Further research is needed to elucidate the effects of different types of exercise on leptin synthesis and secretion in horses. 相似文献
2.
Samples from subhorizons Ol, Of, and Oh of forest soils were separated be screening them into five disintegration fractions. Metal contents have been determined in individual fraction. With increasing transformation of the organic material in the most samples there proceeds a concentration of heavy metals in the order: Fe>Cu>Ni>Zn>Pb; in the same time, content of Mn decreases. Among alkali and alkaline earth metals content of Mg increases and content of Ca decreases. Na and K contents do not show definite relationships with disintegration degree of the organic material. The present results illustrate the trends in the changes in concentrations of various metals due to processes of mineralization and humification of the organic material under definite biocenotic and habitat conditions. 相似文献
3.
Background River and lake sediments constitute complex and difficult analytical samples. On the other hand, sediments play a fundamental
role in the distribution of toxic compounds in aquatic systems and in the evaluation of the current state and the course of
changes taking place in the environment.
Among elements present in the environment in trace concentrations, but having well-elaborated toxic properties, one of most
dangerous is arsenic. The element occurs in the environment in several chemical forms, predominant are inorganic forms of
As(V) and As(III), and methylated forms such as monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA).
Objectives Reported herein are experiments, which were undertaken with the aim of examining the dynamics of arsenic sorption in sediments
and its dependence on speciation of the element and the pH in the environment. Simultaneously, influence of organic matter
content and chemical composition of the sediments on As sorption, were investigated.
Methods Sediment samples (upper 10 cm layer) were collected from three sites located in the vicinity of Cracow:
Using XRD and IR methods, mineral composition of sediments was analysed. Concentrations of iron, manganese, aluminium and
arsenic as well as organic matter content in solid samples were analysed.
Sorption experiment 100 g of dry sediment sample was placed in a 400 ml volume glass beaker. 300 ml of arsenic containing solution was poured
into the beaker. Every 30 min (total experiment time span equalled 7 to 7.5 hours), 0.5 ml of the suspension’ (the beaker
content was constantly mixed) was collected and centrifuged, and the concentration of arsenic was determined in the supernatant.
In the series of experiments, solution contained about 0.05 μg/ml of arsenic in organic (DMAA) and inorganic forms, at different
pH values — 3, 5, 7 and 9.
Results and Discussion Examined sediments of Vistula river and Dobczyce Lake were characterised by relatively high concentrations of arsenic, iron,
manganese and aluminium.Rudawa river. At pH 3, the concentration of inorganic As in solution decreased from an initial value of 0.049 μg/ml to 0.012 μg/ml in
7.5 hours time. The same decreasing tendency was found at pH 5 (initial value 0.046 μg/ml, after 7.5 hours - 0.015 μg/ml).
Less distinct sorption effects were noted at pH 7 and 9.
Vistula river. At all pH values, a very significant decrease of inorganic As concentration up to 80% of the initial value, as well as a
short time of achieving an equilibrium state (1 – 2.5 hours), was found.
Dobczyce lake. Inorganic As was distinctly accumulated in sediments at pH 3 (decrease of As concentration in solution from 0.052 to 0.007
μg/ml after 7.5 hours of the experiment) and at pH 5. At pH 7, about 40% of As was accumulated in sediments (solution As concentration
decrease from 0.050 to 0.030). Only 20% of As adsorbed on sediments at pH 9.Very weak accumulation of organic form of As (DMAA)
was found in all examined sediments at pH 3 and 5. At higher pH values no sorption was registered.
Conclusions The following facts were established:
Recommendations The presented method of analysis of As sorption in sediments and results visualization (based on a newly defined coefficient)
provides a useful tool for the characterization of sorptive properties of sediments and may be used for other compounds as
well. Crucial, functional information — how much of a given element may be accumulated in sediments at a certain pH — is obtained
without digestion of the sediment sample, in an experiment taking less than one day. 相似文献
• | Rudawa river — 37 km long river, flowing mainly through the suburban area; |
• | Vistula river — heavily contaminated, main Polish river; |
• | Dobczyce reservoir — artificial reservoir on Raba river, total capacity of 125,000,000 m3, supplying about 60% of drinking water to the city of Cracow. |
• | inorganic form of arsenic was effectively accumulated in all analysed sediments; |
• | inorganic As sorption in sediments strongly depended on pH — for sediments of Rudawa river and Dobczyce lake, the highest sorption was found at pH 3, and a decrease of accumulated As was noted with an increase of pH (at pH 9, the lowest amount of As was immobilised in sediments); in the case of Vistula river sediments, a reverse tendency was found; |
• | organic form of arsenic (DMAA) was accumulated only at pH 3 in all sediments and less significantly at pH 5 (Vistula river sediments); no sorption of that form of As was found in the other sediment samples; |
• | state of equilibrium (no change in inorganic As concentration in liquid medium) was achieved in 1 hour for Vistula river sediments, after about 2 hours for Rudawa river and after about 4 hours for Dobczyce lake sediments. |
4.
Marcin K. Widomski Steffen Beck Broichsitter Alexander Zink Heiner Fleige Rainer Horn Witold Stępniewski 《植物养料与土壤学杂志》2015,178(3):401-412
At the end of waste disposal in 2005, a temporary mineral system was constructed to cover the waste body of the municipal landfill in Rastorf (N Germany). The aim of this study was to evaluate the effectiveness of this temporary cover system in limiting the infiltration of surface water into the waste body. The numerical modeling for the hydrological year 2012 was performed in FEFLOW 6.0. The required input data for modeling were achieved by laboratory measurements of the saturated hydraulic conductivity and the water retention characteristics of the mineral layers. The assumed initial and boundary conditions were based on in‐situ measurements of matrix potential and volumetric water content at three different measuring points by tensiometers, FDR sensors and observed meteorological conditions. The model was applied according to Darcy's and Richards' equations for variably saturated flow. Our results allowed assessing the components of water balance for a temporary cover system, especially water seepage into the waste body. The correlation between the measured and modeled volumetric soil water content in the layered temporary cover system was observed (R2 = 0.56 to 0.90). Deviations between the measured and modeled values are superficially related to the soil´s heterogeneity. In conclusion, the measured and modeled water balance parameters indicate that the temporary coverage system remains effective in limiting the infiltration rate. However, our studies revealed that the calculated and measured water seepage exceeded the values allowable by the German regulations. Additional studies have to assess variations in the soil water characteristics caused by weather‐related wetting and drying cycles and influence of waste settlement changing the profile of slope. 相似文献
5.
The effect of relaxing massage on heart rate and heart rate variability in purebred Arabian racehorses 下载免费PDF全文
Sylwester Kowalik Iwona Janczarek Witold Kędzierski Anna Stachurska Izabela Wilk 《Animal Science Journal》2017,88(4):669-677
The objective of this study was to assess the effect of relaxing massage on the heart rate (HR) and heart rate variability (HRV) in young racehorses during their first racing season. In the study, 72 Purebred Arabian racehorses were included. The study was implemented during the full race season. The horses from control and experimental groups were included in regular race training 6 days a week. The horses from the experimental group were additionally subject to the relaxing massage 3 days a week during the whole study. HR and HRV were assumed as indicators of the emotional state of the horses. The measurements were taken six times, every 4‐5 weeks. The HRV parameters were measured at rest, during grooming and saddling the horse and during warm‐up walking under a rider. The changes of the parameters throughout the season suggest that the relaxing massage may be effectively used to make the racehorses more relaxed and calm. Moreover, the horses from the experimental group had better race performance records. 相似文献
6.
Roman Gancarz Witold Wielkopolski Elbieta Jaskuska Pawel Kafarski Barbara Lejczak Przemyslaw Mastalerz Jan Sylwester Wieczorek 《Pest management science》1985,16(3):234-238
9-Aminofluoren-9-ylphosphine oxides and the corresponding 9-hydroxy analogues were synthesised and evaluated for herbicidal activity using Spirodela oligorrhiza (Kurz.) Hegelm. All the test compounds were highly active at concentrations of about 10 μM and were comparable with the corresponding phosphonic esters. 相似文献
7.
The aim of this study was to explore the hypothesis that the emotional response of naive purebred Arabian colts and fillies to initial training is lower in the case of sympathetic methods compared with the traditional training methods, and that the response is differentiated with regard to the sex. A group of 32 young purebred Arabian horses was included in the initial training. Half of the group was subjected to a natural training method, and the other 16 horses were trained using a traditional method. Both groups comprised an equal number of colts and fillies. The training lasted a few days, as shortly as possible, with regard to individual horse’s needs. The emotional response of horses to training process was assessed with heart rate measured telemetrically. A horse’s response to sympathetic and traditional training methods depends on its sex. The sympathetic training method modifies the response of colts more than it influences the response of fillies. It is concluded that the natural method is particularly desired in training colts. 相似文献
8.
The composition of the soil organic matter in soil developing under the influence of vegetation during the primary succession in the poor sandy area was investigated. The Curie-point pyrolysis method coupled with gas chromatographic separation and mass spectrometric identification of pyrolysates was applied during the investigation. A comparison of occurrence and diversity in composition of organic compounds in plant tissues and humus horizon of soils under the communities of coniferous forest series in the initial stages and phases was carried out. A large diversity of organic compounds under Algae-Cyanophyta communities, biological soil crusts and Polytrichum piliferum was noticed. A clear differentiation in the composition of the soil organic matter at different phases of succession under predominating communities with cryptogamous and vascular plants was observed. The analysis of organic compounds in plant tissues was found to facilitate the determination of origin of various groups of organic compounds in the soil. The results obtained from the Curie point pyrograms in the humus horizon (A) under grasses (Corynephorus canescens, Koeleria glauca) differed from the pyrolysates obtained under Algae-Cyanophyta communities. The polysaccharide derivates are more frequent in the pyrolysis products under algae, grasses (Corynephorus canescens, Koeleria glauca) and mosses than under Pinus sylvestris. In the beginning of the terminal stage of succession, lignin, phenols and aliphatic substances, prevailed over the polysaccharide derivates in the humus horizon. 相似文献
9.
Witold Wielkopolski Robert
mieszek Stanislaw Witek Andrzej Dabrowski Piotr Wieczorek Barbara Lejczak Pawel Kafarski 《Pest management science》1994,40(2):107-112
Isoxazole-substituted 1-aminoethyl- and 1-hydroxyethyiphosphonates were synthesized by a multi-step procedure and were screened for herbicidal activity against Lepidium sativum L. and Cucumis sativus L. All the synthesized compounds exhibited notable herbicidal activity. 相似文献
10.
The Forgotten Rural Landscapes of Central and Eastern Europe 总被引:1,自引:0,他引:1
Hannes Palang Anu Printsmann Éva Konkoly Gyuró Mimi Urbanc Ewa Skowronek Witold Woloszyn 《Landscape Ecology》2006,21(3):347-357
Interactions between nature and man – the underlying forces in landscape – have over time caused diversity. Usually, geographers
and landscape ecologists deal with spatial diversity; in this paper, we would like to also consider temporal diversity. We
argue that Central and Eastern European landscapes (using the examples of Estonia, Hungary, Poland and Slovenia) are much
more diverse in time (layers) than Western European ones. This difference requires the use of different indicators in order
to measure and study landscapes and special problems, threats, and possibilities of management and future development – but
most important is the consideration of different perceptions. We also show that this diversity reduces the readability of
landscapes, creating miscommunication and a transformation of meanings. We further argue that the link between humans and
landscape is lost in Central and Eastern European countries due to temporal diversity, and that this link will be created
anew in a globalizing world. To overcome alienation, we need slightly different classifications/typologies for each country
in this region, with the aim of a sound future management of cultural landscapes. 相似文献