69 research outputs found

    Supplementary data for article: Andjelković, U.; Milutinović-Nikolić, A.; Jović-Jovičić, N.; Banković, P.; Bajt, T.; Mojović, Z.; Vujčić, Z.; Jovanović, D. Efficient Stabilization of Saccharomyces Cerevisiae External Invertase by Immobilisation on Modified Beidellite Nanoclays. Food Chemistry 2015, 168, 262–269. https://doi.org/10.1016/j.foodchem.2014.07.055

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    The external invertase isoform 1 (EINV1) was immobilised on eight differently modified beidellite nanoclays, Modifications were composed of organo-modification with different amounts of surfactant - hexadecyl trimethylammonium cation (HDTMA), pillaring with Al/Fe containing polyhydroxy cations and acid modification of Na-enriched and pillared clays. The modified nanoclays were characterised by XRD, N-2-physisorption, SEM and FT-IR spectroscopy. The amount of bound enzyme activity was significantly influenced by the modification of beidellite ranging from 50 to remarkable 2200 U/g. Biochemical characterization was performed for five modified nanoclays showing the highest enzyme activity after invertase immobilisation. The investigation demonstrated that after immobilisation the structure and the catalytic properties of invertase were preserved, while Km values were slightly increased from 26 to 37 mM. immobilisation significantly improved thermal and storage stability of EINV1. Results indicate that beidellite nanoclays obtained by low cost modifications can be applied as a suitable support for the immobilisation of invertase. The immobilizate can be efficiently engaged in sucrose hydrolysis in batch reactor.Supplementary material for: [https://doi.org/10.1016/j.foodchem.2014.07.055]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1865

    Uticaj modifikacije na strukturna, teksturalna i adsorpciona svojstva bentonita

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    Natural bentonite clay from the Bogovina locality in Serbia was Na-exchanged and modified using hexadecyll-trimethylammonium bromide as surfactant and organobentonite was obtained. The influence of modifications on the structural, textural and sorption properties of bentonite was investigated. It was estimated that modifications solely replace exchangeable cations in smectite layers, whereas other admixture minerals (quartz, calcite, feldspar) in bentonite remain unaffected. According to X-ray results the modification lead to changes in the smectite structure by either decreasing, for Na-bentonite, or increasing, for organobentonite, the interplanar spacing, d(001). The appearance of three new bands in IR spectra of HDTMA-bentonite comparing to those of raw and Na-bentonite assigned to the methylene vibrations confirmed the embedding of aliphatic cations into smectite structure. In organobentonite a significant change in textural properties was observed. In particular, specific surface area dramatically decreased while originally meso and microporous material became almost completely non-porous. Despite almost insignificant specific surface area the synthesized organobentonite due to gained organophyllity of its surface exhibits exquisite adsorption properties toward investigated textile dyes having adsorption capacity approx. 2 times higher than activated carbon.Prirodna bentonitna glina sa lokaliteta Bogovina u Srbiji je natrijumski izmenjena i modifikovana heksadeciltrimetil amonijum-bromidom kao surfaktantom, pri čemu je dobijen organobentonit. Ispitivan je uticaj modifikacije na strukturu, teksturalna i adsorpciona svojstva bentonita. Utvrđeno je da primenjeni postupci modifikacije dovode isključivo do izmene katjona u medulamelamom sloju smektita, dok modifikacija ne deluje na druge prateće minerale u bentonitu (kvare, kalcit, feldspat). Uprkos neznatnoj specifičnoj površini sintetizovani organobentonit zahvaljujući novodobijenoj organofilnosti površine pokazuje izuzetna adsorpciona svojstva prema tekstilnim bojama, imajući adsorpcioni kapacitet oko 2 puta veći od aktivnog uglja

    Co(II) impregnated Al(III)-pillared montmorillonite–Synthesis, characterization and catalytic properties in Oxone® activation for dye degradation

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    Aluminum pillared clay was synthesized and impregnated with Co2+ (CoAP), using incipient wetness impregnation method. The obtained CoAP was characterized by chemical analysis, XRPD, SEM with EDS, XPS and low temperature N2 physisorption. By these methods the incorporation of Co2+ was confirmed in both micro and mesoporous region. The synthesized material was investigated as a catalyst in catalytic oxidation of organic water pollutants – dyes – in the presence of Oxone® (peroxymonosulfate). Oxone® is a precursor of sulfate radicals. Tartrazine was chosen as a model dye pollutant. The influence of the mass of the catalyst, temperature and initial pH was investigated. Temperature increase was beneficial for dye degradation rate. The reaction rate was the highest for initial pH values around those corresponding to neutral conditions, somewhat slower for pH 10 decolorization was significantly less expressed. Along with decolorization of tartrazine solution the formation and degradation of tartrazine catalytic oxidation products were monitored using UV–Vis spectroscopy. CoAP was found to be efficient catalyst in Oxone® induced catalytic degradation of both tartrazine and detected products of its degradation.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3375

    Antiproliferative and Proapoptotic Activities of Methanolic Extracts from Ligustrum vulgare L. as an Individual Treatment and in Combination with Palladium Complex

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    The aim of this study is to examine the growth inhibitory effects of methanolic leaf and fruit extracts of L. vulgare on HCT-116 cells over different time periods and their synergistic effect with a Pd(apox) complex. The antiproliferative activity of plant extracts alone or in combination with the Pd(apox) complex was determined using MTT cell viability assay, where the IC50 value was used as a parameter of cytotoxicity. Results show that antiproliferative effects of L. vulgare extracts increase with extension of exposure time, with decreasing IC50 values, except for 72 h where the IC50 values for methanolic leaf extract were lower than for the fruit extract. The Pd(apox) complex alone had a weak antiproliferative effect, but combination with L. vulgare extracts caused stronger effects with lower IC50 values than with L. vulgare extracts alone. The type of cell death was explored by fluorescence microscopy using the acridin orange/ethidium bromide method. Treatments with plant extracts caused typical apoptotic morphological changes in HCT-116 cells and co-treatments with Pd(apox) complex caused higher levels of apoptotic cells than treatment with plant extracts alone. The results indicate that L. vulgare is a considerable source of natural bioactive substances with antiproliferative activity on HCT-116 cells and which have a substantial synergistic effect with the Pd(apox) complex

    World virtual globes

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    The article deals with some possibilities of presenting and visualising geospatial data. The Internet is especially useful for analyzing and detection of geospatial reality and its features. In the field of geodesy and cartography the use of the Internet is very impressive. Virtual atlases have become very attractive

    Application of GIS from the multifunctionality aspect

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    Application of computer technology in the Earth science has led to the creation and development of new scientific disciplines, particularly digital cartography and GIS. This paper describes the application of GIS from several points of view such as: multi-scale, multi-thematic, multi-viewing, accommodation to standard software platforms and multi-user data accesses. Introduction The premise of a successful usage of topographic data nowadays implies their disposal in a digital form and organisation in a modern way, suitable for further computer processing. It is a unanimous opinion that it can be successfully completed only through creating data basis of space developing GIS. The theme of the written work is the development and application of GIS, and management of topographic data in accordance with international standards and users' needs. Moving to digital technology of creating and using topographic data should not be literal translation of the analogue map into a digital picture or just the automation of the map making using digital technology. The new method implies the formation of the central topographic data base which would generate displays of arbitrary scales, desired volumes of content, changeable sheet dimensions, various thematic displays, altogether in accordance with users' demands and needs. Digital cartography and GIS The development and application of computers in the area of earth sciences caused the creation of new definitions and disciplines among which are noticeable computer supported cartography and GIS. The computer-supported cartography was in its later phase called digital cartography and it can be used in two ways: like modern technology of date processing about space and like a new discipline. The main principle on which digital cartography as a discipline is based represents the processing and visualization of data about space but with computer supported technology. Application of GIS from various aspects Topographic maps have existed for many years in more or less similar or the same traditional form. By creating the basic data base about space through the application of GIS technology, a wide range of possibilities for dynamic selection of content appears. This content will further be shown on the screen or as a drawing on a piece of paper. The aspects of multidisciplinarity promote topographic data base as a significant part of general spatial data infrastructure. Application from the multiscale aspect There are different information levels which differ among themselves in quantity and content of data necessary for various levels of observation management and decision making. One of the principal tasks which emerges is a choice of the basic scale and resolution of the display for which the data are gathered. In cartography, that is a scale of 1:25,000, based on which the topographic map (TM) is created. Mutual complement of GIS and WWW will completely change the classic delivery of spatial data. Various topographic and thematic maps will be created and obtained from the unique data base. Application from the multithematic aspect The main objective of the formation of spatial data infrastructure is the creation of the standard GIS platform but also the possibility of multi purpose application of GIS for environment (farming, forestry, waterpower engineering) land development (commercial and business), itinerary analysis, tracing of retail and wholesale routes distributional nets (shops and warehouse locations) media and marketing planning (locations, sales territory, sales prospects, market analysis according to users), finances - insurance (from the users aspect, investors and areas of low/high risk), healthcare (general healthcare, appearance of epidemic and its spreading) and non-productive activities (tourism, archaeology, environment protection). Application from the aspect of multidisplay Once formed, the spatial data base, or GIS, should offer to the user a lot of graphic, descriptive and other important information which is, in fact, a digital or traditional display in a form of a determined output. One of the ways of using GIS implies cartographic publishing (getting the reproductive originals and printing geographic map sheets) in a traditional form. Application from the aspect of adjustment to standard software platforms In the groundbreaking period of civilization with radical changes in a scientific - technological sphere, it was necessary to select a new, most suitable software platform with attaching hardware components. After thorough analyses (analyses of foreign and national literature and the usage of demo versions of various GIS software), the American company ESRI software platform was selected. Application from the aspect of multiusers data access Internet and Intranet are deeply rooted technologies and have been increasingly used as technologies to accomplish the growing number of distributed informational systems. Therefore, the above-mentioned technologies are needed for distributed work with spatial data. Maintenance of GIS data The maintenance of the topographic data denotes a process of updating old-fashioned content and entering new geospatial data as well as the elimination and the correction of details which are not in accordance with the real state on the field. In connection with the volume and the method of work, difference should be made between the spatial data maintenance aspects for the basic scale, which refer to the entire content and specific elements of the content. Regarding periods in which the present space data maintenance is done, there are continuous and periodical ones. Conclusion When establishing the unique GIS, we ought to apply a principle according to which all the data once gathered in one State institution can be used variedly as well as in many other institutions (military, administrative, economic, scientific, cultural, etc.). This principle does not apply only to the rationalization but also to uniqueness and quality of the research of common geospace. In the present state of the development, it is hard to predict the trends of cartographic and generally speaking GIS processes, but the most important is that topographic data have digital form the meaning of which is universal, regardless of the current development of technique and technology

    Effects of the control method (Goč variety) in selection forest management in Western Serbia

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    The control method, one of the most reliable methods of selection forest management, has been applied in selection forests of western Serbia in a somewhat modified form (Goč variety) for fifty years. This paper analyzes the effects of the control method, i.e. its Goč variety, in the period from 1960/70 - 2000. It is based on the data of five successive complete inventories of the Forest Management Unit (FMU) 'Tara', whose high selection forest of spruce, fir and beech (Piceo-Abieti-Fagetum subass. typicum) trees on diluvium, brown and illimerised soil on limestone, and on limestone in formation with hornfels, are the best quality and the most spacious forests in the Management Class MC 491/1. The effects were monitored through the changes in the distribution of the number of trees and volume per diameter classes, separately for fir as the protagonist of the selection structure, and collectively at the level of a compartment, a typical representative of MC 491/1. Also, the analysis included the changes in the number of trees, volume, current volume increment, yield, and number of recruited trees per unit area (1 ha) by tree species in MC 491/1, occupying an area of 2,648.78 ha. The study results show that in the study period the average volume in MC 491/1 increased by 18.8%, the percentage of conifers increased from 66.0% to 78.5%, and the bearer of the changes was fir. The volume of the mean fir tree increased by 35.9% and it attained 1.086 m3. The volume increment increased by 15.7%. The selection structure of conifers was satisfactory, but there were problems with beech regeneration, in its stable presence and in its achievement of the targeted structure. The number of trees per unit area (1 ha) decreased, which in the long run could have detrimental consequences, but the sustainability in general was satisfactory. The levels of regeneration and recruitment were satisfactory. The health of the trees was improved; the stands were healthy, vital, and biologically and functionally stable. The study results point not only to a series of positive effects of the several-decades' long implementation of the Goč variety of the control method, but also to some problems, the understanding of which will have a corrective role in the future management of selection forests in western Serbia

    Traditional vs. innovative uses of computers among mathematics pre-service teachers in Serbia

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    This study examined pre-service teachers’ intentions to use computers in traditional and innovative teaching practices in primary mathematics classrooms. It extended the technology acceptance model (TAM) by adding as external variables pre-service teachers’ experience with computers and their technological pedagogical content knowledge (TPCK). Data collected from 226 participants revealed that the proposed model had a good fit for both traditional and innovative uses of computers. Structural equation modelling suggested that the established TAM variables, together with TPCK and experience, were significant determinants of pre-service teachers’ intentions to use computers in teaching mathematics at both levels. The most dominant determinant of behavioural intention was TPCK, followed by attitude. The proposed model explained 22.7% of the variance in the use of computers in traditional teaching practices and 27.6% of the variance in the use of computers in innovative teaching practices. The implications for mathematics teaching are discussed in the final section
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