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31.
The influence of mesoscale weather patterns on the chemical composition of daily precipitation samples is analysed. The data of pH, sulphur from sulphates and total nitrogen are analysed for two rural sites: Plitvice station in forested part of Central Croatia (1981 to 1990) and Puntijarka suburban station on the mountain near Zagreb, the capital of Croatia (1982–1991). The two prevailing weather types in precipitation days are selected and the comparison of chemical composition of precipitation is made for each of them. The frequency distributions of pH, sulphur and nitrogen show that concentration of major ions in precipitation apparently depends on the regional scale weather type. It is shown that the seasonal variation of deposition is related to the seasonal variation in precipitation amount. In both weather types Plitvice receives more pollution than Puntijarka that is closer to urban and industrial pollution sources. Both locations are under the prevailing influence of regional pollution sources. 相似文献
32.
33.
Salières P Carré B Le Déroff L Grasbon F Paulus GG Walther H Kopold R Becker W Milosević DB Sanpera A Lewenstein M 《Science (New York, N.Y.)》2001,292(5518):902-905
Atoms interacting with intense laser fields can emit electrons and photons of very high energies. An intuitive and quantitative explanation of these highly nonlinear processes can be found in terms of a generalization of classical Newtonian particle trajectories, the so-called quantum orbits. Very few quantum orbits are necessary to reproduce the experimental results. These orbits are clearly identified, thus opening the way for an efficient control as well as previously unknown applications of these processes. 相似文献
34.
Terracciano A Abdel-Khalek AM Adám N Adamovová L Ahn CK Ahn HN Alansari BM Alcalay L Allik J Angleitner A Avia MD Ayearst LE Barbaranelli C Beer A Borg-Cunen MA Bratko D Brunner-Sciarra M Budzinski L Camart N Dahourou D De Fruyt F de Lima MP del Pilar GE Diener E Falzon R Fernando K Ficková E Fischer R Flores-Mendoza C Ghayur MA Gülgöz S Hagberg B Halberstadt J Halim MS Hrebícková M Humrichouse J Jensen HH Jocic DD Jónsson FH Khoury B Klinkosz W Knezević G Lauri MA Leibovich N Martin TA 《Science (New York, N.Y.)》2005,310(5745):96-100
Most people hold beliefs about personality characteristics typical of members of their own and others' cultures. These perceptions of national character may be generalizations from personal experience, stereotypes with a "kernel of truth," or inaccurate stereotypes. We obtained national character ratings of 3989 people from 49 cultures and compared them with the average personality scores of culture members assessed by observer ratings and self-reports. National character ratings were reliable but did not converge with assessed traits. Perceptions of national character thus appear to be unfounded stereotypes that may serve the function of maintaining a national identity. 相似文献
35.
Zhou M Morgner N Barrera NP Politis A Isaacson SC Matak-Vinković D Murata T Bernal RA Stock D Robinson CV 《Science (New York, N.Y.)》2011,334(6054):380-385
The ability of electrospray to propel large viruses into a mass spectrometer is established and is rationalized by analogy to the atmospheric transmission of the common cold. Much less clear is the fate of membrane-embedded molecular machines in the gas phase. Here we show that rotary adenosine triphosphatases (ATPases)/synthases from Thermus thermophilus and Enterococcus hirae can be maintained intact with membrane and soluble subunit interactions preserved in vacuum. Mass spectra reveal subunit stoichiometries and the identity of tightly bound lipids within the membrane rotors. Moreover, subcomplexes formed in solution and gas phases reveal the regulatory effects of nucleotide binding on both ATP hydrolysis and proton translocation. Consequently, we can link specific lipid and nucleotide binding with distinct regulatory roles. 相似文献
36.
Branimir Jovančićević Miroslav Vrvić Jan Schwarzbauer Hermann Wehner Georg Scheeder Dragomir Vitorović 《Water, air, and soil pollution》2007,183(1-4):225-238
A review is given in this paper of the up-to-date results observed in differentiation and transformation studies on petroleum-type pollutants in underground and surface waters. Water and particulate matter derived from the locality of Pan?evo Petroleum Refinery, Serbia (River Danube alluvial formations). It was shown that distributions of n-alkanes, steranes and triterpanes, and δ13CPDB values of n-alkanes may successfully be used for qualitatively differentiating the petroleum-type pollutants from native organic matter in recent sedimentary formations. In underground waters, a petroleum-type pollutant is exposed to microbiological degradation which is manifested through relatively fast degradation of n-alkanes. Following an almost complete degradation of crude oil n-alkanes in underground water, the biosynthesis of novel, even carbon-number C16–C30 n-alkanes may be observed. It is shown that the n-alkane distribution observed in a petroleum-type pollutant may depend on the intensity of its previous interaction with water. The fate of petroleum-type pollutants in environmental waters may be predicted through laboratory simulative microbiological degradation experiments by using microorganism consortiums similar to those observed under relevant natural conditions, as well as on corresponding nutrient base. 相似文献
37.
Jelena Petrović Snežana Dragović Ranko Dragović Milan Đorđević Mrđan Đokić Mirjana Ćujić 《Journal of Soils and Sediments》2016,16(4):1168-1175
Purpose
The area of southeastern Serbia, the P?inja and South Morava River Basins, is under the influence of very strong erosion, and the aim of this study was to investigate the vertical and spatial distribution of the 137Cs in the eroded soils of this area.Materials and methods
Vertical soil profiles were collected with 5-cm increments from the uppermost layer down to 20, 25, 30, 40, and 50 cm of depth, depending on the thickness of the soil layers, i.e., down to the underlying parent rocks. Measurements of 137Cs activity concentration were performed by using the HPGe gamma-ray spectrometer ORTEC-AMETEK (34 % relative efficiency and high resolution 1.65 keV at 1.33 MeV for 60Co), from its gamma-ray line at 661.2 keV.Results and discussion
The mean 137Cs activity concentration across all 18 soil profiles (for all soil layers) was found to be 20 Bq kg?1. In the greatest number of soil profiles, the 137Cs activity concentration was generally highest in the first soil layer (0–5 cm) and decreased with soil depth, while in a few soil profiles, the peak of either the 137Cs activity concentration occurred in the second soil layer (5–10 cm) or the 137Cs activity concentration was almost equal throughout the entire soil profile. The mean 137Cs activity concentration in the first soil layer (0–5 cm) was found to be 61 Bq kg?1, and the high coefficient of variation of 92 % pointed out high spatial variability and large range of the 137Cs activity concentrations in the study area.Conclusions
The obtained results indicate that in the greatest number of soil profiles, 137Cs is present in the upper layers, with concentration decreasing with depth, as is typical in uncultivated soil. Its spatial distribution was very uneven among the surface soil layers of the investigated sites. One of the main reasons for such pattern of 137Cs in the study area may be soil erosion. Additional investigations which would support this hypothesis are required.38.
Michael Ochs Ivano Brunner Werner Stumm BoŽena ćosović 《Water, air, and soil pollution》1993,68(1-2):213-229
The effect of complex natural organic ligands on the weathering kinetics of aluminum oxide was investigated in laboratory experiments. A peat-derived humic substance and root exudates obtained from ectomycorrhizal (Picea abies — Hebeloma crustuliniforme) and non-mycorrhizal Norway Spruce trees; and γ-Al2O3 were used as a model system. The experimental weathering rates are in accordance with a surface-controlled dissolution mechanism. The effect of the humic material on dissolution rates appears to depend on the degree of protonation of the humic (macro)molecules: we observed dissolution-enhancement or -inhibition at pH 3 and 4, respectively. Ectomycorrhizal exudates proved to be effective weathering agents at pH 4, as opposed to humic material and non-mycorrhizal exudates. Our results suggest that (i) the role of humic materials in mineral weathering and podzolization is different from what is commonly thought, and (ii) mineral weathering rates in the rhizosphere may be higher than in the bulk soil. 相似文献
39.
Skrbić B Durisić-Mladenović N Cvejanov J 《Journal of agricultural and food chemistry》2005,53(6):2171-2175
Trace elements (Cu, Fe, Pb, Hg, Cd, As, Mn, Zn) were analyzed quantitatively in 14 wheat samples collected from fields in all Serbian growing regions, harvested in 2002. Microelements were determined according to an atomic absorption spectrophotometric method. Principal component analyses (PCA) were performed on data matrices consisting of contents of trace elements in wheats (columns) and all Serbian wheat-growing regions (rows). It was found that four principal components account for 87.2% of the total variance in the data. The plot of component loadings showed significant groupings for concentration of some microelements. The component scores indicated the similarities among the Serbian wheat-growing regions. The loading plot reveals that there is no need to measure all of the variables to achieve the same classification. It is enough to measure one variable per group. Naturally, this conclusion is valid only within the limits of the present study of wheat grain samples from different parts of Serbia. 相似文献
40.
Slađana Č. Alagić Snežana B. Tošić Mile D. Dimitrijević Jelena V. Petrović Dragana V. Medić 《Communications in Soil Science and Plant Analysis》2016,47(17):2034-2045
Inductively coupled plasma optical emission spectroscopy, in combination with calculation of various biological factors, was used in this study not only for a simple illustration of the present status of some essential and non-essential metals such as copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), arsenic (As), and cadmium (Cd) in the grapevine cultivar Rkatsiteli and wild blackberry from East Serbia but also for the estimation of plant bioaccumulation potentials. Great majority of detected metal concentrations were in normal ranges except in few cases: Zn concentrations were at the level of deficiency in almost all plant parts, and some Cu and As concentrations were at the levels that could be considered phytotoxic. Biological accumulation factors provided very informative data on metal accumulation and translocation in both plants and pointed to low accumulation rates of metals except in the case of Cu, Zn, and As in some wild blackberry tissues. 相似文献