25 research outputs found
Quantifying Self-Organization with Optimal Wavelets
The optimal wavelet basis is used to develop quantitative, experimentally
applicable criteria for self-organization. The choice of the optimal wavelet is
based on the model of self-organization in the wavelet tree. The framework of
the model is founded on the wavelet-domain hidden Markov model and the optimal
wavelet basis criterion for self-organization which assumes inherent increase
in statistical complexity, the information content necessary for maximally
accurate prediction of the system's dynamics. At the same time the method,
presented here for the one-dimensional data of any type, performs superior
denoising and may be easily generalized to higher dimensions.Comment: 12 pages, 3 figure
Teški metali u vodi gradske vodovodne mreže Novog Beograda
In this work, the subject of research is the scale formed by heating the drinking water that
flows through the city water supply of New Belgrade. Analysis of the scale showed that its
main ingredient is CaCO3, but in the scale and in drinking water could be found alkali and
alkaline earth metals, heavy metals, semimetals and radioactive elements.
In tested drinking water elements whose presence in large quantities is not desirable (eg,
Pb) are proven to exist, as well as elements that, so far, have not been found in the water of the
Belgrade water supply (eg, Ni). Based on the results of fractional analysis, it is concluded that
the uranium found in the scale and in the drinking water is in the form of potentially accessible
and mobile fractions which indicate its anthropogenic origin.
Analysis of scale, with all the parameters of scale existing (water flow, temperature, etc..),
presents an indirect method of analyzing the quality of drinking water, especially for low levels
of pollutants which are harmful to the human body.Predmet ispitivanja u radu bio je kamenac nastao zagrevanjem vode za piće
koja protiče kroz gradsku vodovodnu mrežu Novog Beograda. Analiza kamenca
pokazala je da je njegov glavni sastojak CaCO3, ali se u kamencu, a samim tim i u vodi
za piće, nalaze i alkalni i zemnoalkalni metali, teški metali, polumetali i radioaktivni
elementi.
U ispitivanoj vodi za piće dokazani su elementi čije prisustvo u većoj količini nije
poželjno (npr. Pb), ali i elementi koji, do sada, nisu nađeni u vodi beogradskog
vodovoda (npr. Ni). Na osnovu rezultata frakcione ekstrakcije, zaključuje se da se uran
u kamencu, a samim tim i u vodi za piće, nalazi u obliku potencijalno pristupačnih i
mobilnih frakcija koje ukazuju na njegovo antropogeno poreklo.
Analiza kamenca, uz poznavanje svih parametara nastanka kamenca (protok vode,
temperatura i dr.), predstavlja posrednu metodu analize kvaliteta vode za piće, posebno
za polutante niskih sadržaja štetnih za ljudski organizam
Kv1.3 potassium channels involved in the antihypertensive effects of resveratrol : [abstract]
Ispitivanje sadržaja nitrita, nitrata i amonijaka u vodi za piće
In this paper is shown, an investigation of the quality of drinking water in rural
areas without central water supply around Požarevac city, based on the content of
nitrite, nitrate and ammonia.
The most common cause for unsafe drinking water are the increased values of
nitrates (the highest concentration of 1138.9 mg/dm3) and nitrite (the highest
concentration of 0.40 mg/dm3).
In all analyzed samples of drinking water in rural areas ammonia concentration is in
acceptable limits.U ovom radu izvršeno je ispitivanje kvaliteta vode za piće u seoskim
naseljima na teritoriji grada grada Požarevca koja nemaju centralno vodosnabdevanje,
na osnovu sadržaja nitrita, nitrata i amonijaka.
Najčešći uzrok neispravnosti vode za piće su povišene vrednosti nitrata (najviša
koncentracija od 1138,9 mg/dm3) i nitrita (najviša koncentracija od 0,40 mg/dm3).
U svim analiziranim uzorcima vode za piće u seoskim naseljima koncentracija
amonijaka je u dozvoljenim granicama
Ispitivanje korelacije faze razvoja pšenice sorte Pobeda i udaljenosti od industrijske zone na dinamiku usvajanja teških metala u pojedinim delovima biljke
In selected parts of the wheat plant variety Pobeda in various stages of growth examined
the content of heavy metals. Samples were taken from the fields and regions are at different
distances from the oil refinery in Pančevo. Determination of heavy metals was carried out by
atomic absorption spectrophotometry in the flame acetylene/air,
Research on the effects of varieties, stage of wheat development and distance from the
industrial zone on the dynamics of the adoption of heavy metals in some parts of the wheat
plant (root and stem) was carried out on experimental fields of the Institute ”Tamiš” in the
fields of Old Tamiš and Vojlovica.
The results showed significant differences between the distance from the refinery to the
content of heay metals in different parts of the wheat plant.Na odabranim delovima biljke pšenice sorte Pobeda u različitim fenofazama
ispitivan je sadržaj teških metala. Uzorci su uzimani sa polja i regiona koji su na
različitoj udaljenosti od Rafinerije nafte u Pančevu. Ispitivanje teških metala je
obavljeno primenom atomske apsorpcione spektrofotometrije. Istraživanja korelacije
faze razvoja pšenice i udaljenosti od industrijske zone na dinamiku usvajanja teških
metala u pojedinim delovima biljke (koren i stablo) obavljeno je na uzorku pšenice sorte
Pobeda sa Oglednog polja Instituta „Tamiš”, polja Starog Tamiša i Vojlovice. Dobijeni
rezultati prikazali su značajnost razlike između udaljenosti od Rafinerije u odnosu na
sadržaj teških metala u različitim delovima biljke pšenice
Endothelium-independent effect of pinacidil on saphenous vein obtained from patients with/without type 2 diabetes mellitus through voltage-gated potassium channels : [abstract]
Reticulation of aqueous polyurethane systems controlled by DSC method
The DSC method has been employed to monitor the kinetics of reticulation of aqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium (CAT(R) XC- 6212) and the highly selective manganese catalyst, the complex Mn(III)diacetylacetonemaleinate (MAM). Among the polyol components, the acrylic emulsions were used for reticulation in this research, and as suitable reticulation agents the water emulsible aliphatic polyisocyanates based on hexamethylendoisocyanate with the different contents of NCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger, Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reaction of aqueous systems were determined. The temperature of the examination ranged from 50 degrees C to 450 degrees C with the heat rate of 0.5 degrees C/min. The reduction of the activation energy and the increase of the standard deviation indicate the catalytic action of the selective catalysts of zirconium and manganese. The impact of the catalysts on the reduction of the activation energy is the strongest when using the catalysts of manganese and applying all the three afore-said methods. The least aberrations among the stated methods in defining the kinetic parameters were obtained by using the manganese catalyst
Spectroscopic characteristics of highly selective manganese catalysis in acqueous polyurethane systems
The latest investigations on producing more efficient catalytic aqueous polyurethane systems are in the domain of metal complexes with mixed ligands. In our previous research works, the high selectivity for the isocyanate-hydroxyl reaction in aqueous polyurethane systems has been shown by the manganese(III) mixed-ligand complexes. The two new complexes have been prepared with two acetylacetonate (acac) ligands and one maleate ligand and its hydroxylamine derivative of the general formula [Mn(C5H7O2)(2)L]. Their structures have been established by using the fundamental analyses, the FTIR and UV/VIS spectroscopic methods, as well as the magnetic measurements. In order to explain the different selectivity of the manganese(III) mixed-ligand complexes, the UV and ESR spectroscopy have been employed to determine the kinetics of the complexes' decomposition. The thermal stability of the complexes has been determined by way of the dynamic TG method at the heating rate of 5 degrees C.min(-1) and at the temperature ranged 20-550 degrees C. It suggests the decomposition of the complexes by loss of acid ligand. The main factor in the selective catalysis control in the aqueous polyurethane systems is the nature of the acid ligands and their impact on the manganese(II)/manganese(III) equilibrium
Thermal stability of aqueous polyurethanes depending on the applied catalysts
The thermal stability of aqueous polyurethanes has been measured applying the thermogravimetric analysis. The aqueous polyurethanes (aqPUR) with catalysts of different selectivity have been studied by use of the dynamic method. To obtain degradations of 0.025, 0.05, and 0.10, employing the dynamic method, the heating rates of 0.5, 1, 2, 5, and 10 degrees C min(-1) have been used in the range of 30-500 degrees C. Using the more selective catalysts in the aqueous polyurethanes, the total resulting time of the decompositon has been on the increase at all degrees of the degradation and at the particular starting temperature. This paper shows that the dynamic method based on the thermogravimetric analysis can be used to assess the thermal stability of the aqueous polyurethanes using the catalysts of different selectivity
Primena metode atomske apsorpcione spektrofotometrije (AAS) za određivanje sadržaja teških metala u prehrambenim proizvodima kojima su napunjene konzerve od lakiranog belog lima
Due to possibility of contamination of food products caused by a rapid pollution of environment, as a consequence of incidents and accidents, it is necessary to exert a regular and systematic control of the content of heavy metals in tins filled with food products for the purpose of disease prevention and protection of public health. Foodstuffs, which can be of heterogeneous chemical composition contain or a considerable quantity of water, organic acids, sodium-chloride, nitrates, anthocynes, etc. are added which are the potential co rodents of metals in contact with the contents of tins. The contamination of food products in tins can also occur because of a breakthrough of a protective tin lacquer, or a poor quality of a packaging material. The consequence of the corrosion of tins is the increase of concentration of metals, especially heavy metals, the deterioration of organoleptic characteristics of foodstuff and even the perforation of tins. The atomic absorbing spectropholometer is widely used in practice for determining the content of heavy metals because of its high sensitivity (10-6 g and less), accuracy (about 1%), selectivity and the possibility of application in defining the contents of more than 20 elements. The analyzed tins were filled with pasteurized sour cherry, pasteurized apricot mash, pasteurized plum halves and sterilized peas. The aim of this research was to define the content of heavy metals in food kept in lacquered tinplate tins. Furthermore, its aim was also to determine whether the content of heavy metals in foods, upon having been tinned for several months, changes and reaches the legal level and suchlike tins can be used in human nutrition.Usled mogućnosti kontaminacije prehrambenih proizvoda zbog rapidnog zagađenja životne sredine, kao posledica incidenata i akcidenata, neophodno je vršiti redovnu i sistematsku kontrolu sadržaja teških metala u konzervama napunjenim prehrambenim proizvodima, u cilju prevencije i zaštite zdravlja stanovništva. Namirnice, koje mogu biti heterogenog hemijskog sastava sadrže, ili im se dodaje znatna količina vode, organskih kiselina, kuhinjske soli, nitrata, antocijana i dr., koji su potencijalni uzročnici korozije metala u kontaktu sa sadržajem konzervi. Do kontaminacije prehrambenih proizvoda u konzervama može doći usled proboja zaštitnog laka konzerve ili lošeg kvaliteta ambalažnog materijala. Kao posledica korozije konzervi, dolazi do povećanja koncentracije metala, naročito teških metala, do pogoršanja organoleptičkih svojstava namirnice, pa i perforacije konzervi. Za odredivanje sadržaja teških metala veliku primenu u praksi ima atomski apsorpcioni spektrofotometar, zbog visoke osetljivosti (10-6 g i manje), preciznosti (oko 1%), selektivnosti i mogućnosti primene za određivanje sadržaja preko 20 elemenata. Ispitivane konzerve punjene su pasterizovanom višnjom, pasterizovanom kašom kajsije, pasterizovanom polutkom šljive i sterilisanim graškom. Cilj ovoga rada bio je utvrđivanje sadržaja teških metala u prehrambenim proizvodima koji su se nalazili u konzervama od lakiranog belog lima. Takođe, cilj rada bio je da se utvrdi da li se sadržaj teških metala u prehrambenim proizvodima, nakon višemesečnog stajanja u konzervama, menja i dostiže zakonom dozvoljeni nivo i da li se takve konzerve mogu koristiti u ljudskoj ishrani