Structure analysis of geopolymers synthesized from clay originated from Serbia     

Snežana S. Nenadović  Ljiljana M. Kljajević  Maja A. Nešić  Marijana Ž. Petković  Katarina V. Trivunac  Vladimir B. Pavlović 《Environmental Earth Sciences》2017,76(2):79

The paper presents chemical and structural analysis of geopolymer materials which are obtained by alkali-activated calcined clay (metakaolin) originated from Serbia under strictly defined conditions. Characterization of the metakaolin and geopolymers molecular structure has been done using X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The paper presents the possibility of obtaining geopolymer structure and differences in chemical and structural characterization of these materials taking into account the concentration of NaOH as a variable parameter. The results of MALDI analysis of metakaolin and synthesized geopolymer structures using various matrix system: 2,4,6 trihydroxyacetophenone (THAP), α-cyano-4-hydroxycinnamic, 2,6 dihydroxyacetophenone and laser desorption/ionization, have shown that THAP matrix is the most appropriate for analysing these aluminosilicate materials.  相似文献   

Numerical modelling of reinforced‐concrete structures under seismic loading based on the finite element method with discrete inter‐element cracks          下载免费PDF全文

Željana Nikolić  Nikolina Živaljić  Hrvoje Smoljanović  Ivan Balić 《地震工程与结构动力学》2017,46(1):159-178

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Free-Free Absorption in Solar Atmosphere     

Dimitrijević  M. S.  Srećković  V. A.  Sakan  N. M.  Bezuglov  N. N.  Klyucharev  A. N. 《Geomagnetism and Aeronomy》2018,58(8):1067-1072

Geomagnetism and Aeronomy - The free-free i.e. electron-ion inverse “Bremsstrahlung” characteristics are determined for the case of the solar atmosphere as well as solar interior where...  相似文献   

Analysis of the Relationship Between the Solar X-Ray Radiation Intensity and the D-Region Electron Density Using Satellite and Ground-Based Radio Data     

Aleksandra Nina  Vladimir M. Čadež  Jovan Bajčetić  Srdjan T. Mitrović  Luka Č. Popović 《Solar physics》2018,293(4):64

Increases in the X-ray radiation that is emitted during a solar X-ray flare induce significant changes in the ionospheric D region. Because of the numerous complex processes in the ionosphere and the characteristics of the radiation and plasma, the causal-consequential relationship between the X-ray radiation and ionospheric parameters is not easily determined. In addition, modeling the ionospheric D-region plasma parameters is very difficult because of the lack of data for numerous time- and space-dependent physical quantities. In this article we first give a qualitative analysis of the relationship between the electron density and the recorded solar X-ray intensity. After this, we analyze the differences in the relationships between the D-region response and various X-ray radiation properties. The quantitative study is performed for data observed on 5 May 2010 in the time period between 11:40 UT?–?12:40 UT when the GOES 14 satellite detected a considerable X-ray intensity increase. Modeling the electron density is based on characteristics of the 23.4 kHz signal emitted in Germany and recorded by the receiver in Serbia.  相似文献   

Responses of a Northern Adriatic Ampelisca-Corbula community to seasonality and short-term hydrological changes in the Po river     

N'siala GM  Grandi V  Iotti M  Montanari G  Prevedelli D  Simonini R 《Marine environmental research》2008,66(4):466-476

During the 20th century, increased nutrient inflow has increased the frequency and intensity of eutrophication events in the North-western Adriatic Sea. More recently, evidence of a reduction in the Po river flow and a recovery of the benthic environment were reported. We examined the role played by Po river regime and seasonality in determining the temporal pattern of macrozoobenthos variation: samples were collected from a site located 10-12km off Cesenatico during two years from October 2004 to September 2006, when the mean Po discharge remained exceptionally low. 88 taxa were found, and the community was dominated by few species: Ampelisca diadema, Lumbrineris latreillii, Corbula gibba, Aricidea claudiae, Levinsenia gracilis and Nucula nucleus account for about 80% of total abundances. The density of these species exhibited a marked seasonal variability. Moreover, the total abundance and the density of the sensitive species, A. diadema, were negatively affected by several disturbance events (hypoxic conditions, frequent storms and an anomalous winter flood) that occurred between November 2005 and March 2006. The reduction of C. gibba and the increase of A. diadema densities observed in the investigated period, and verified recently by other authors could be related to the reduction in river inputs as a consequence of climatic changes.  相似文献   

Cloning and mRNA expression analysis of an ABCG2 (BCRP) efflux transporter in rainbow trout (Oncorhynchus mykiss) liver and primary hepatocytes     

Zaja R  Munić V  Smital T 《Marine environmental research》2008,66(1):77-79

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Land use optimization for sustainable development of mountain regions of western Serbia   总被引：1，自引：0，他引：1  

Tijana VULEVI?  Mirjana TODOSIJEVI?  Nada DRAGOVI?  Miodrag ZLATI? 《山地科学学报》2018,15(7):1471-1480

This study analyses the possibilities for optimal land use structure in mountainous areas of rural Serbia, which is faced with problems such as unfavorable terrain characteristics and inadequate land use patterns causing economic underdevelopment and increasing population migration. In the case of a small privately owned farm in Western Serbia, optimal land use pattern is determined using the linear programming model. The objective function-cost-effectiveness or soil erosion reduction, as well as constraints, are formulated using the benefit-cost ratio (BCR) for a 15-year production period and soil losses data calculated using the Universal Soil Loss Equation (USLE). The best results are achieved using the scenario with the aim to minimize soil erosion, considering the BCR in the constraints. This scenario is proposed since it was registered that the benefit for landowners would increase by five times, while the losses of land would decline about 80%. The sensitivity analysis of investments is performed to check whether the price variation affects the cost-effectiveness of proposed land use. Results show that market changes (nine cases are considered) do not lead to significant changes in land use allocation. Proposed land use pattern improves the environmental condition, strengthens the rural economy and thus offers the greatest potential for sustainable development of mountainous rural areas.  相似文献   

A Relationship Between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups     

Domagoj Ruždjak  Roman Brajša  Davor Sudar  Ivica Skokić  Ivana Poljančić Beljan 《Solar physics》2017,292(12):179

The sunspot position published in the data bases of the Greenwich Photoheliographic Results (GPR), the US Air Force Solar Optical Observing Network and National Oceanic and Atmospheric Administration (USAF/NOAA), and of the Debrecen Photoheliographic Data (DPD) in the period 1874 to 2016 were used to calculate yearly values of the solar differential-rotation parameters \(A\) and \(B\). These differential-rotation parameters were compared with the solar-activity level. We found that the Sun rotates more differentially at the minimum than at the maximum of activity during the epoch 1977?–?2016. An inverse correlation between equatorial rotation and solar activity was found using the recently revised sunspot number. The secular decrease of the equatorial rotation rate that accompanies the increase in activity stopped in the last part of the twentieth century. It was noted that when a significant peak in equatorial rotation velocity is observed during activity minimum, the next maximum is weaker than the previous one.  相似文献   

Assessing the ecological status of the North-western Adriatic Sea within the European Water Framework Directive: a comparison of Bentix, AMBI and M-AMBI methods     

Roberto Simonini  Valentina Grandi  Gloria Massamba-N'Siala  Mirko Iotti  Giuseppe Montanari  & Daniela Prevedelli 《Marine Ecology》2009,30(2):241-254

In this paper we looked for the most suitable method for benthic ecological quality status (EcoQS) assessment of the North-western Adriatic Sea. Taking into account the historical and present information, we inter-compared our expectations in terms of EcoQS, with the Bentix, AMBI and M-AMBI classification metrics results, and investigated the sensitivity of these indices to the spatial, seasonal and inter-annual variability of benthic communities. The sampling sites were located at increasing distances with respect to the Po River mouth, along an (inverse) gradient of eutrophication. Moreover, a 2-year monthly monitoring plan (October 2004–September 2006) was carried out at the CEBEB site, located in a central position with respect to the investigated area. The results highlighted that the three indices differed in the sensitivity to spatial and temporal variability of the benthic communities. The strong seasonal and inter-annual changes in the benthic communities had a significant effect on the Bentix, whereas no relevant modifications were observed on the EcoQS assignation obtained using the M-AMBI and AMBI methods. The environmental quality ratios (EQR) values and EcoQS classification obtained by the Bentix and AMBI did not match expectations, as they were not inversely correlated with the site distances with respect to the Po mouth, whereas the M-AMBI clearly discriminated the most and the least eutrophicated sites. It thus appears that the M-AMBI could be considered to be the most valuable method for the ecological-status assessment of the North-western Adriatic Sea benthic ecosystem.  相似文献   

DNA damage and apoptosis in the mussel Mytilus galloprovincialis   总被引：4，自引：0，他引：4  

Micić M  Bihari N  Jaksić Z  Müller WE  Batel R 《Marine environmental research》2002,53(3):243-262

The effects of known genotoxic substances (4-nitroquinoline-N-oxide, benzo[a]pyrene, teniposide, etoposide, cycloheximide, tributyltin) on human cells (FLC, HL-60) and on mussels were investigated. The correlations between formation of DNA strand breaks and DNA fragmentation characteristic for the process of apoptosis were estimated. Strand breaks induced by 4-nitroquinoline-N-oxide and benzo[a]pyrene did not correlate with DNA fragmentation detected in the process of apoptosis. Induction of internucleosomal DNA fragmentation in HL-60 cells was initiated by teniposide, etoposide and tributyltin, while in the gills of mussels this was detected only with tributyltin. Levels of DNA strand breaks in natural mussel populations, living at locations under the influence of urban and industrial wastes, do not mirror the apoptotic processes.  相似文献