Uticaj procesa izluživanja i načina korišćenja rendzina na stepen humificiranosti huminskih kiselina

The humification degrees of humic acids extracted from calcareous and decarbonated Rendzinas under different land use were characterized upon their optical properties, to evaluate the influence of carbonate leaching (decarbonation) and different land uses. Decarbonation influenced the humification degree of humic acids positively. Base leaching and acidification of decarbonated Rendzinas led to a decrease in humification degree of humic acids. In calcareous Rendzinas, the humification degree of humic acids was in descending order: grassland>arable land>forest land, and in decarbonated Rendzinas: arable land>grassland>forest land. The humification degree of humic acids was higher in the calcareous forest and grassland Rendzinas compared to decarbonated Rendzinas, analogously in decarbonated arable land compared to calcareous arable land Rendzinas. Differences in the humification degree of humic acids among various land uses that emerged between calcareous and decarbonated Rendzinas indicate the dominant influence of soil chemical characteristics (carbonate content and pH value) compared with the quantity and quality of the organic litter input.Prema domaćoj klasifikaciji, rendzine su zemljišta sa moličnim A horizontom koji postepeno prelazi u rastresiti karbonatni C horizont. Primarno su karbonatna, i njihova evolucija teče u pravcu izluživanja pa zatim posmeđivanja. Najčešće su pod prirodnom šumskom i travnom vegetacijom, manji deo njih se obraduje. U ovom radu su ispitivane optičke osobine huminskih kiselina zemljišta tipa rendzina, a istraživanja su imala za cilj praćenje posledica izluživanja i promene načina korišćenja ovog tipa zemljišta u Srbiji na stepen humificiranosti huminskih kiselina. Priprema rastvora huminskih kiselina za VIS spektroskopiju izvedena je metodom Kononove. Karakterizacija optičkih osobina huminskih kiselina je data preko optičkih indeksa: E4/E6, ΔlogA i RF. Rezultati su obrađeni u programu StatSoft, Inc. Statistica, Version 8. Proces izluživanja je pozitivno uticao na stepen humificiranosti huminskih kiselina u rendzinama (najveći je pri neutralnoj reakciji). Dalja debazifikacija i acidifikacija izluženih rendzina uticala je negativno, odnosno dovela do smanjenja stepena humificiranosti huminskih kiselina. Stepen humificiranosti huminskih kiselina u karbonatnim rendzinama se kretao travnjak>njiva>šuma, a u izluženim rendzinama njiva>travnjak>šuma. Huminske kiseline karbonatnih rendzina pod šumom i travnjakom su imale veći stepen humificiranosti u poredenju sa izluženim rendzinama pod šumom i travnjakom. U izluženim rendzinama pod njivom stepen humificiranosti huminskih kiselina je bio veći nego u karbonatnim rendzinama pod njivom. Razlike u stepenu humificiranosti huminskih kiselina prema načinu korišćenja koje su se pojavile između karbonatnih i izluženih rendzina ukazuju na dominantan uticaj hemijskih karakteristika zemljišta na osobine huminskih kiselina u poredenju sa količinom i kvalitetom organskih ostataka koji dospevaju u zemljište

Supplementary data for the article: Lakic, M.; Vukadinovic, A.; Kalcher, K.; Nikolic, A. S.; Stankovic, D. M. Effect of Cobalt Doping Level of Ferrites in Enhancing Sensitivity of Analytical Performances of Carbon Paste Electrode for Simultaneous Determination of Catechol and Hydroquinone. Talanta 2016, 161, 668–674. https://doi.org/10.1016/j.talanta.2016.09.029

Supplementary material for: [https://doi.org/10.1016/j.talanta.2016.09.029]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2343

Optimizacija i primena gasno-difuzione protočne injekcione metode za određivanje hlorida

A selective and sensitive procedure for the fast and indirect determination of chloride by the gas-diffusion FIA method has been optimized and applied for the determination of chloride in water samples which contained different amounts of the analyte. The examined samples were: seawater, tap water and very pure water from the water-steam system of the power plant "Nikola Tesla B" in Obrenovac. Application of an amperometric detector (model LC-17A; BAS, West Lafayette, USA) enables the detection limit to be decreased down to 0.05 mu mol/dm(3) of chloride, which col responds to 35.5 pg, and adjustment of the acceptor flow rate and direction inside the gas-diffusion unit. In this way the optimized FIA system has excellent repeatability. For 5 mu mol/dm(3) it was found to be 1.11% (n = 5). The throughput of this method is 60 samples per hour.Selektivan i osetljiv postupak za brzo, indirektno određivanje hlorida gasno-difuzionom metodom otpimizovan je i primenjen za određivanje hlorida u uzorcima voda sa vrlo različitim sadržajem ove vrste: morskoj, vodi za piće i vrlo čistim vodama u sistemu voda-para TE "Nikola Tesna B" u Obrenovcu. Upotreba amperometrijskog detektora tipa LC-17A omogućava snižavanje granice detekcije na 0.05 μmol/dm3 hlorida (što za uzorak zapremine 0.2 cm3 iznosi 35.5 pg) i podešavanje brzine i smera toka u gasno-difuzionoj jedinici. Ovako optimizovan protočni sistem ima odličnu reproduktivnost. Za hloridni standard koncentracije 5 μmol/dm3 relativna standardna devijacija iznosi 1.11 % (n = 5)

Feriti juče-danas-sutra

Ferrites, well-known group of magnetic materials, are one of the most interesting materials applicable in many fields of engineering, due to their remarkable electrical and magnetic properties, and wide practical applications. The new synthetic routes have been intensively studied nowadays by chemists. Brief overview of the preparation as well as relationship between properties and synthetic procedures applied are given in the text

Feriti juče-danas-sutra

Ferrites, well-known group of magnetic materials, are one of the most interesting materials applicable in many fields of engineering, due to their remarkable electrical and magnetic properties, and wide practical applications. The new synthetic routes have been intensively studied nowadays by chemists. Brief overview of the preparation as well as relationship between properties and synthetic procedures applied are given in the text

Geomorfološko proučavanje Bigra na lokalitetu Bigreni potok (Donja Bela Reka)

The tufa accumulations in the valley of Bigreni stream are morphogenetically complex. The great importance for the occurrence of tufa, as in majority of other accumulations in Eastern Serbia, has the vicinity of the karst spring. The presence of cascades in the gorge of Bigreni stream enabled primary formation of waterfall tufa. After partitioning the gorge, the phase of the barrier tufa accumulation began. The erosive phase is currently present and therefore, once unique accumulation has been divided into several smaller accumulations. The possibility for protection because of the vicinity of the protected capped spring and the beauty of tufa waterfalls indicate the potential for tourist exploitation of this locality.Bigarene akumulacije u dolini Bigrenog potoka morfogenetski su složene. Veliku važnost za pojavu bigra, kao i kod većine drugih akumulacija u Istočnoj Srbiji, ima blizina kraškog vrela. Postojanje kaskada u klisuri Bigrenog potoka omogućilo je prvobitni nastanak vodopadnog bigra. Nakon pregrađivanja klisure počinje faza akumulacije barijernog bigra. Trenutno je aktuelna erozivna faza pa je, nekada jedinstvena akumulacija, podeljena u više manjih. Mogućnost zaštite, usled blizine zaštićene kaptaže, i lepota bigrenih vodopada ukazuju na potencijal za turističku eksploataciju ovog lokaliteta

Geomorfološko proučavanje Bigra na lokalitetu Bigreni potok (Donja Bela Reka)

The tufa accumulations in the valley of Bigreni stream are morphogenetically complex. The great importance for the occurrence of tufa, as in majority of other accumulations in Eastern Serbia, has the vicinity of the karst spring. The presence of cascades in the gorge of Bigreni stream enabled primary formation of waterfall tufa. After partitioning the gorge, the phase of the barrier tufa accumulation began. The erosive phase is currently present and therefore, once unique accumulation has been divided into several smaller accumulations. The possibility for protection because of the vicinity of the protected capped spring and the beauty of tufa waterfalls indicate the potential for tourist exploitation of this locality.Bigarene akumulacije u dolini Bigrenog potoka morfogenetski su složene. Veliku važnost za pojavu bigra, kao i kod većine drugih akumulacija u Istočnoj Srbiji, ima blizina kraškog vrela. Postojanje kaskada u klisuri Bigrenog potoka omogućilo je prvobitni nastanak vodopadnog bigra. Nakon pregrađivanja klisure počinje faza akumulacije barijernog bigra. Trenutno je aktuelna erozivna faza pa je, nekada jedinstvena akumulacija, podeljena u više manjih. Mogućnost zaštite, usled blizine zaštićene kaptaže, i lepota bigrenih vodopada ukazuju na potencijal za turističku eksploataciju ovog lokaliteta

Assessment of karst geomorphosites on Kucaj and Beljanica mountains as a resource for the development of karst-based geopark

Protection and promotion of geoheritage has been changing and improving in recent decades, in line with the growing research in this field. Some research papers specifically study geomorphological geoheritage and introduce a special term - geomorphosite. Karst geomorphosites present specific objects of geomorphological heritage. On Kucaj and Beljanica mountains there is the largest karst area in Serbia. The purpose of this paper is to select and evaluate the scientific value of karst geomorphosites of Kucaj and Beljanica. More than one hundred karst geomorphosites were analyzed. In order to achieve more adequate coverage and representation, they were grouped into 25 geomorphotypes in three major geomorphological components of the investigated area. The results of this analysis highlighted the most important natural potentials of this area for establishing a karst-based geopark. More than 20 geomorphotypes have a positive recommendation index, which provides a good basis for further geotourism analysis

Mehanohemijska sinteza nikal i nikal-cink feritnih prahova sa Nicolson-Ross analizom absorpcionih koeficijenata

The interest in finding new methods for the preparation of nickel ferrite (NiFe2O4) and nickel-zinc ferrite (NixZn1-xFe2O4) powders has recently increased, because the physical and chemical properties of these soft magnetic materials depend strongly on the preparation conditions. In this study, powder samples of ferrites were obtained by: 1) a classic sintering procedure (NixZn1-xFe2O4, x = 0.9) and 2) planetary mill synthesis (both NiFe2O4 and the NixZn1-xFe2O4). The mechano-chemical reaction leading to the formation of the spinel phase of NixZn1-xFe2O4 (x = 1 or 0.9) was monitored by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) analysis. The values of the real and imaginary parts of the permittivity and permeability were measured for the obtained nickel and nickel-zinc ferrite samples in the 7-12 GHz frequency range. Based on the obtained results, the electromagnetic radiation (EMR) absorption coefficients were calculated for all three types of sample. It was concluded that the method of preparation and the final particle size influence the EMR absorption coefficient of nickel and nickel-zinc ferrites.U novije vreme povećan je interes za pronalaženje novih metoda za sintezu nikal-ferita (NiFe2O4) i nikal-cink-feritnih (NixZn1-xFe2O4) prahova, zbog činjenice da fizička i hemijska svojstva ovih 'mekih' magnetnih materijala u mnogome zavise od uslova pripreme. Dobijeni feritni prahovi, opisani u ovom radu, sintetisani su: 1) klasičnom procedurom sinterovanja (NixZn1-xFe2O4, x = 0,9 ili 2) sintezom u planetarnom mlinu (NiFe2O4 i NixZn1-xFe2O4). Prosečna veličina čestica dobijenih prvom metodom iznosi 3-5 μm, dok druga metoda daje čestice veličine 10-12 nm. Karakterizacija uzoraka praćena je skenirajućom elektronskom mikroskopijom (SEM), transmisionom elektronskom mikroskopijom (TEM), kao i difrakcionom analizom X-zracima (XRD). Realni i imaginarni delovi koeficijenata permitivnosti i permeabilnosti su mereni na dobijenim uzorcima nikal i nikal-cink-ferita u frekventnom opsegu 7-12 GHz. Na osnovu dobijenih rezultata, izračunati su EMR apsorpcioni koeficijenti za sve dobijene uzorke. Zaključeno je da je način pripreme, kao i dobijena veličina čestica, utiču na EMR apsorpcione koeficijente nikal i nikal-cink-ferita

In situ XRPD and DSC study of order-disorder phase transition in nanosize Li-ferrite

An order-disorder phase transition of nanosize Li-ferrite (Li0.50Fe2.50O4) was studied by DSC measurements and in situ XRPD technique. The phase transition temperature is found to be 762 °C (DSC) and (745±5) °C (XRPD).Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200