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Упит dcterms_subject_txt:Natural two dimensional materials

743 items

  • Surface functional groups and degree of carbonization of selected chars from different processes and feedstock

    Marija Ilić, Franz-Hubert Haegel, Aleksandar Lolić, Zoran Nedić, Tomislav Tosti, Ivana Sredović Ignjatović, Andreas Linden, Nicolai D. Jablonowski, Heinrich Hartmann (2022)
    The knowledge ofthe structural and chemical properties of biochars is decisive for their application as technical products. For this reason, methods for the characterization of biochars that are generally applicable and allow quality control are highly desired. Several methods that have shown potential in other studies were used to investigate two activated carbons and seven biochars from different processes and feedstock. The chars were chosen to cover a wide range of chemical composition and structural properties as a hardness ...
    Biougalj, različiti procesi dobijanja, različite sirovine, površinski aktivne grupe, x-ray, FT-IR,XPS
    ... respectively [53]. The activated carbons are characterized by a strong decrease of intensity at low angles, which is typical for amorphous materials and two broad peaks at around 24" and 43.5" due to the presence of turbostratic carbon. AC1 also shows a sharp peak of quartz in agreement with the ...
    ... broadening of bands and the bands at 795 and 781 cm ' suggests the presence of carbonized material. Since the spectra of carbonized materials are dominated by two strong and broad signals with minima at 1550 + 50 and 1110 + 110 cm ! bands of other origin in these ranges might be shifted. The bands ...
    ... and the materials were mixed by stirring with a spatula. The mixture was wetted with electrolyte solu- tion and stirred again. The materials were filled into the sample holders in portions. Therefor, some electrolyte was first poured into the sample holders and then the solid materials were added ...

  • Crystal structure of K3EuSi2O7

    Sabina Kovač, Predrag Dabić, Aleksandar Kremenović (2021)
    alkalni silikati elemenata retkih zemalja, kristalna struktura, sinteza metodom fluksa, rendgenska difrakcija na monokristalu
    ... Thus, the crystal structure of this compound, K3EuSi2O7, has not been described in the literature so far. EXPERIMENTAL Materials and measurements All the materials were of analytical reagent grade and used as received without further purification. The crystal structure of K3EuSi2O7 was analyzed ...
    ... OnLin e Fir st 6 KOVAČ et al. The structure is characterized by two crystallographically distinct six- coordinated sites occupied by Eu1 and Eu2: Eu1O6 is an octahedron (OC-6) and Eu2O6 is a trigonal prism (TPR-6). Two types of polyhedra around europium cations are distinguished by a small ...
    ... of a wide range of optical and magnetic properties combined with high thermal stability.1‒9 All this makes them very interesting and promising materials for different applications. REE silicates also exhibit a broad structural diversity.10 A highly adaptive framework can incorporate almost all REEs ...

  • The influence of Al<sup>3+</sup>ion on porcine pepsin activity<i>in vitro</i>

    Vesna M. Pavelkić, Kristina R. Gopcević, Danijela Z. Krstić, Marija A. Ilić (2008)
    The in vitro effect of Al3þ ions in the concentration range 1.7·1026M–8.7·1023M on pepsin activity at pH 2, via kinetic parameters and its electrophoretic mobility was evaluated. Kinetic study demonstrated the existence of an activation effect of Al3þ at pH 2 on pepsin molecule. Kinetic analysis with respect to concentrations of haemoglobin showed that Al3þ ions increase the maximal velocity (Vmax) and kcat values rather than apparent affinity for substrate (KS) implying the non-competitive nature of activation which indicated ...
    Пепсин, алуминијум, кинетика, активација, електрофоретска мобилност
    ... 4] Blundell'TL, Jenkin J, Sewell BT, Pearl LH, CooperJB, Tickle1J, Veerapandian B, Wood SP. X-ray analyses of aspartic proteinases. The three-dimensional structure at 2.1 A resolution of endothiapepsin. J Mol Biol 1990;211:919—0941. 5] Pedersen VB, Foltmann B. The amino acid sequence of a hitherto ...
    ... resolutions. J Mol Biol 1990;214:43—170. 8] Cooper JB, Khan G, Taylor G, Tickle IJ, Blundell TL. X-ray analyses of aspartic proteinases. II. Three-dimensional [9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 P+ 1009 Zlctivation ...
    ... located at· the centre of the b{ndmg cleft study related enzymes. As all aspartic proteinases between the domains. One of two Asp residues has to pepsin molecule consist of two homologous lobes · be protonated and the other deprotonated, for the composed predominantly of B-sheets separated by a protein ...

  • Adsorption and degradation of some psychiatric drugs by sol-gel synthesized titania-based photocatalysts: influence of tungsten and sodium content

    Nina L. Finčur, Maja J. Šćepanović, Mirjana Grujić-Brojčin, Biljana F. Abramović, Jugoslav B. Krstić, Aleksandar Kremenović, Tatjana Srećković, Aleksandar Golubović (2019)
    Mesoporous anatase nanopowders were doped with 0.05−0.5 mol% of W6, in order to obtain more efficient photocatalyst than TiO2 Degussa P25 in the degradation of amitriptyline (AMI) under simulated solar irradiation (SSI). Dominant XRPD peaks were ascribed to anatase phase, with additional peaks which could correspond to brookite, TiO2 bronze and sodium titanate, Na2Ti9O19. The Raman scattering measurements have confirmed anatase as dominant phase, with broad Raman feature at ~270 cm−1 possibly related to Ti–O–Na stretching vibration. All W-doped ...
    Sol-gel synthesis, Doped titania nanopowders, XRPD, Raman spectroscopy, Adsorption and photocatalytic degradation, Psychiatric drugs

  • Part of Speech Tagging for Serbian language using Natural Language Toolkit

    Ranka Stanković, Boro Milovanović (2020)
    Dok se razvijaju složeni algoritmi za NLP (obrada prirodnog jezika), osnovni zadaci kao što je označavanje ostaju veoma važni i još uvek izazovni. NLTK (Natural Language Toolkit) je moćna Python biblioteka za razvoj programa zasnovanih na NLP-u. Pokušavamo da iskoristimo ovu biblioteku za kreiranje PoS (vrsta reči) oznake za savremeni srpski jezik. Jedanaest različitih modela je kreirano korišćenjem NLTK API-ja za označavanje. Najbolji modeli se transformišu sa Brill tagerom da bi se poboljšala tačnost. Obučili smo modele na označenom ...
    obrada prirodnog jezika, mašinsko učenje, neuronske mreže
    ... Part of Speech Tagging for Serbian language using Natural Language Toolkit Ranka Stanković, Boro Milovanović Дигитални репозиторијум Рударско-геолошког факултета Универзитета у Београду [ДР РГФ] Part of Speech Tagging for Serbian language using Natural Language Toolkit | Ranka Stanković, Boro Milovanović ...
    ... available at: www.dr.rgf.bg.ac.rs Abstract—While complex algorithms for NLP (Natural language processing) are being developed, base tasks such as tagging remain very important and still challenging. NLTK (Natural Language Toolkit) is a powerful Python library for developing programs based on ...
    ... tagger: 92,52 – 95,76% accuracy for the different tagsets. Index Terms—Natural Language Processing; Machine Learning; Neural Network. I. INTRODUCTION In the last couple of years, a big advancement in the field of Natural Language Processing has occurred. There are state-of- the-art language ...

  • Application of a Method for Intelligent Multi-Criteria Analysis of the Environmental Impact of Tailing Ponds in Northern Kosovo and Metohija

    Gordana Milentijević, Blagoje Nedeljković, Milena Lekić, Zoran Nikić, Ivica Ristović, Jelena Đokić (2016)
    flotacijska jalovišta, životna sredina, višekriterijumska analiza, ekologija, Trepča
    ... are given in Figure 3. Figure 4 shows a diamond PROMETHEE solution. This solution shows partial PROMETHEE I and final ranking PROMETHEE II in a two-dimensional model. The PROMETHEE diamond solution is presented with the dot on (Phi+,Phi−) flat. The flat is at an angle of 45◦ so that the vertical dimension ...
    ... 77 1.90 3.81 6.67 0.8 * limited values according to the administrative decision on the soil quality (RS Official Gazette, No. 88/2010) [18]. 3. Materials and Methods 3.1. Tailing Ponds The waste tailings from processing of flotation of metallic mineral ores are by-products of MMCC “Trepča” mining ...
    ... dangerous to the surrounding ecosystem. The tailing ponds are unsuitably placed and the current lack of maintenance in addition to the disposed materials can permanently endanger the living environment. At the same time, these ponds represent a potential danger which can reach the category of ecological ...

  • Polymorphism and photoluminescence properties of K3ErSi2O7

    Predrag Dabić, Marko G. Nikolić, Sabina Kovač, Aleksandar Kremenović (2019)
    alkalni silikati elemenata retkih zemalja, silikati lantanoida, polimorfizam, fotoluminescencija, kristalna struktura

  • Application of machine learning for diagnosing the operation of a deep well pump in oil production

    Maja Trikić (2024)
    This paper will thoroughly examine how machine learning can improve the diagnosis of deep well pumps by analyzing the role and function of the pumps, dynamograms, sensor technologies, and diagnostic methods.Our analysis will provide insights into modern techniques and approaches for enhancing the performance and reliability of oil production systems, targeting cost reduction and increased operational efficiency.
    deep well pump, dynamograms, machine learning, diagnostics of operating coditions,Random Forest, XGBoost
    ... typically made from materials such as silicon crystals. Piezoresistive sensors are highly accurate and are often used in applications that require high precision. 31 k Figure5.2 Piezoresistive sensors 3. Capacitive sensors - these sensors use the variable capacitance between two electrodes that ...
    ... on - Using methods like Principal Component Analysis (PCA) or t- Distributed Stochastic Neighbor Embedding (t-SNE), you can visualize high- dimensional data in 2D or 3D space. This can help in identifying patterns in the data that indicate unusual pump conditions or behaviors. b.Discovery of ...
    ... waves to measure flow. There are two main methods: a.Doppler method - Measures changes in the frequency of the sound wave caused by the movement of particles in the fluid. b.Transit-time method - Measures the time it takes for the sound wave to travel between two sensors, which is proportional ...

  • Multihazard Exposure Assessment on the Valjevo City Road Network

    Miloš Marjanović, Biljana Abolmasov, Svetozar Milenković, Uroš Đurić, Jelka Krušić, Mileva Samardžić Petrović (2019)
    Prirodni hazardi, izloženost, klizišta, poplave, bujice, GIS, R

  • Application of Lignite Combustion Waste Slag Generated in Heating Plants as a Partial Replacement for Cement. Part II: Physical–Mechanical and Physical–Chemical Characterization of Mortar and Concrete

    Milan Kragović, Nenad Ristić , Jelena Gulicovski, Andrijana Nedeljković, Snežana Pašalić, Ivica Ristović, Marija Stojmenović (2021)
    sagorevanje lignita, otpadna šljaka, zamena cementa, proizvodnja maltera i betona, fizičko-mehanička i fizičko-hemijska karakterizacija
    ... from the metallurgical industry [12,13]. Additionally, there are some studies which described that the tailings materials generated in gold or copper mines may be used as construction materials, whereby the best results can be obtained after a tailings stabilization via suitable geo-polymerization [14,15] ...
    ... finding its potential useful value. Additionally, it is important to emphasize the fact that for waste materials, constant research must be carried out. Very often, waste generated from different raw materials, origins (deposits, or lots), or treatments can have completely contrasting properties. For these ...
    ... by up to 20%. Additionally, results of the physical–mechanical characterization showed that mortar and concrete materials with 20% of cement replacement may be used as constructional materials in the construction industry. Minerals 2021, 11, 925 11 of 16 3.2. X-Ray-Structural Diffraction Analysis (XRD) ...

  • Open Educational Resources in Serbia

    Ivan Obradović, Ranka Stanković, Marija Blagojević, Danijela Milošević (2020)
    Open educational resources, BAEKTEL, Metadata portal
    ... wider audience. Apart from several OERs related to programming and web design, it includes learning materials on Social Networks analysis, GIS application in geology, Lexical Analysis in Natural Language Processing, Security in IT etc. Khan Academy published mathematics and IT OERs generally ...
    ... goals and teaching materials. According to Espana-Villegas and Caeiro-Rodriguez (2018) confirm that OER include all types of educational content (complete courses (educational programs), course materials, content modules, learning objects, textbooks, multimedia materials (text, sound, video ...
    ... with the aim of improving algorithmic literacy in Serbia through OERs. It includes the portal with learning materials for programming and Takprog, an official website with materials from competitions of secondary school students in Serbia in programming . The BubbleBee Portal was developed ...

  • Geotehnički efekti razaranja komunalnog otpada različitim postupcima zbijanja

    Jovana M. Janković Pantić (2022)
    Odlaganje otpada na komunalne deponije predstavlja osnovni način zbrinjavanja otpada u Srbiji. Kako bi se prostor za deponovanje materijala racionalno koristio potrebno ga je svakodnevno zbijati sa unapred definisanom količinom vode koja se dodaje. Dobro zbijeni komunalni otpad zauzima manju zapreminu i omogućuje sigurnije skladištenje, pa je korisno prethodno laboratorijski odrediti parametre zbijanja: maksimalnu suvu zapreminsku težinu (dmax) i optimalnu vlažnost (wopt). U Srbiji do sada nisu određivani parametri zbijanja, dok je u svetu primenjivana standardna metoda (Proktorov opit) ...
    komunalna deponija, zbijanje, Proktorov opit, malj sa šiljcima, koeficijent razaranja

  • Towards Better Valorisation of Industrial Minerals andRocks in Serbia—Case Study of Industrial Clays

    Vladimir Simić, Dragana Životić, Zoran Miladinović (2021)
    Management, Monitoring, Policy and Law,Nature and Landscape Conservation
    ... sedimentological point of view), and all mineral raw materials used in the clay- based structural products (ceramics), such as loess, oil shales, separation tailings rich in organic matter, products obtained by washing of coal and other natural raw materials. The territory of Serbia is very rich in common ...
    ... with variable quality of mineral raw materials - 50–100 100–200 Deposits of medium size, bedded and lenticular, without uniform structure - 25–50 50–150 Resources 2021, 10, 63 7 of 18 and thickness, with variable quality of mineral raw materials 3 Deposits with very variable structure ...
    ... complicated geological structure, tectonics and strict technological requirements for certain grades of raw materials. In the case of geologically relatively simple deposits (aggregate rocks, raw materials for struc- tural ceramics), equivalence can also be done automatically according to the model pro- posed ...

  • Extensive vibrations of the belt conveyer drive electromotor of a bucket wheel excavator as a result of intesified wear-and-tear of its mount support

    Vesna Damnjanović, Predrag Jovančić, Snežana Aleksandrović (2017)

  • Overcoming the Low Oral Bioavailability of Deuterated Pyrazoloquinolinone Ligand DK-I-60-3 by Nanonization: A Knowledge-Based Approach

    Jelena R. Mitrović , Branka Divović-Matović, Daniel E. Knutson, Jelena B. Ðoković, Aleksandar Kremenović, Vladimir D. Dobričić, Danijela V. Randjelović, Ivana Pantelić, James M. Cook, Miroslav M. Savić, Snežana D. Savić (2021)
    Poor water solubility of new chemical entities is considered as one of the main obstacles in drug development, as it usually leads to low bioavailability after administration. To overcome these problems, the selection of the appropriate formulation technology needs to be based on the physicochemical properties of the drug and introduced in the early stages of drug research. One example of the new potential drug substance with poor solubility is DK-I-60-3, deuterated pyrazoloquinolinone, designed for the treatment of various neuropsychiatric ...
    pyrazoloquinolinones, nanocrystals, wet media milling, fasted/fed bioavailability
    ... Pharmaceutics 2021, 13, 1188 3 of 19 2. Materials and Methods 2.1. Materials DK-I-60-3 was synthesized at the Department of Chemistry and Biochemistry, Uni- versity of Wisconsin—Milwaukee, WI, USA, according to the procedure explained by Knutson et al. [12]. Other materials used in this research are listed: ...
    ... an additional 20 nm in most formulations (Table 3). Two-way ANOVA results showed that interaction between milling time and beads volume had a significant effect on PDI (p < 0.05) in all formulations except F3 and F4. Interestingly, PDI in these two formulations was higher than 0.250, which already raised ...
    ... all substances are suitable candidates for amorphization. Based on the ability to vitrify upon cooling from the melted state or to form a glass, materials can be characterized as glass-formers or non-glass-formers. According to the results of prediction of glass-forming ability for more than 100 pha ...

  • Investigation of quantitative indicators of anisotropy based on longitudinal elastic waves propagation velocities with uncertainty

    Miloš Gligorić, Jelena Majstorović, Suzana Lutovac (2018)
    ... have used two approaches to calculate the degree of anisotropy and one for calculating the anisotropy coefficient. The remainder of the paper is constructed as follows. Section 2 describes basics of interval numbers such as arithmetic operations, maximum and minimum between two interval numbers ...
    ... �̂� is defined as: 𝐸(�̂�) = [1𝑁 ∑ 𝑠𝑖𝑙𝑁 𝑖=1 , 1𝑁 ∑ 𝑠𝑖𝑢𝑁 𝑖=1 ] (1) 9. Maximum and minimum between two interval numbers To determine maximum and minimum between two or more interval numbers, we used the Moore Distance. (Trindade et al., 2010). Firstly, we must define a degenerated ...
    ... waves b) transversal waves Today, ultrasonic waves with frequency over 20 000 Hz are applied in elastic properties investigations of different materials, both in laboratories and „in situ“ conditions. At the end of the seventies in the last century for rock samples investigation (borehole core, ...

  • Assessment of environmental radioactivity and health hazard at Stara Planina region

    Slavko Dimovic, Boris Vakanjac, Ivana Jelic, Milena Rikalovic, Vesna Ristic-Vakanjac, Radoje Bankovic (2021)
    Циљ студије је био да се процени потенцијални ризик од зрачења у близини напуштених рудника уранијума, јаловишта или лежишта уранијума на Старој планини у Србији. За процену ризика одређено је неколико параметара: активност еквивалента радијума, Raeq, екстерни индекс опасности, Hex, брзина апсорбоване дозе гама зрачења, D, годишња ефективна доза на позадинској експозицији гама гама на отвореном, AEDoutdoor и ризик од рака током живота, ELCR. Добијени резултати су показали да сви узорци, осим једног, имају Raeq вредност и до два ...
    природна радиоактивност, животна средина, здравље, опасност, процена ризика

  • Development of Open Educational Resources (OER) for Natural Language Processing

    Cvetana Krstev, Biljana Lazić, Ranka Stanković, Giovanni Schiuma, Miladin Kotorčević (2015)
    In this paper we present the development of an online course at the edX BAEKTEL platform named “Lexical Recognition in the Natural Language Processing (NLP)”. It is based on the course of the same name for PhD studies at the University of Belgrade, Faculty of Philology. There are not many courses in Computational Linguistics (CL) on OER platforms, and there is none in Serbian either for CL or NLP. We have developed this course in order to improve this ...
    E-Learning, Open Educational Resources, Computational Linguistics, Lexical Resources, edX
    ... geoinformatics, mining and environmental protection, geology and natural language processing, the last being in the focus of this paper. Why Study Natural Language Processing (NLP) and Computational Linguistics (CL)? Natural language processing is the technology for dealing with human language ...
    ... Prijedor). BAEKTEL platform is developed in order to enable higher education (HE) institutions to publish their course materials (video lectures, course planning materials and evaluation tools as well as thematic content).The ICT solution includes several components:  OER repository on local ...
    ... Resources (OER) for Natural Language Processing Cvetana Krstev, Biljana Lazić, Ranka Stanković, Giovanni Schiuma, Miladin Kotorčević Дигитални репозиторијум Рударско-геолошког факултета Универзитета у Београду [ДР РГФ] Development of Open Educational Resources (OER) for Natural Language Processing ...

  • Connections between the Levant and the Balkans in the late Middle Pleistocene: Archaeological findings from Velika and Mala Balanica Caves (Serbia)

    Dušan Mihailović, Steven L. Kuhn, Katarina Bogićević, Vesna Dimitrijević, Ana B. Marín-Arroyo, Jelena Marković, Norbert Mercier, Bojana Mihailović, Mike W. Morley, Predrag Radović, William J. Rink, Senka Plavšić, Mirjana Roksandić (2022)
    Major changes in the technological, economic, and social behavior of Middle Pleistocene hominins occurred at the onset of the Middle Paleolithic, 400e200 ka. However, until recently it was not possible to establish when, where, and how certain forms of Middle Paleolithic behavior appeared and spread into Southeastern Europe, mainly owing to gaps in the Paleolithic record. Here we report new results of dating, material culture, and the archaeological context of finds from the Balanica Cave Complex in Sicevo (Serbia). ...
    Neandertalci, starija Kina tehnologija, jabrudijen, populaciona kretanja, kulturni prenos

  • Design of a sucker rod pumping system

    Ana Ponoćko (2024)
    For a long time in the history of oil production, sucker rod pumps have been the first and in many cases the only choice when it comes to mechanical extraction methods. Proper selection of each individual element of the system enables optimization, which entails benefits in the form of increased efficiency and reduced costs. The first part of the paper presents the underground and surface equipment of the rod pump and describes the operation of the entire system. The ...
    sucker rod pump, fluid production, mechanical extraction methods,, Prosper, QROD, RODSTAR
    ... continuous and irreversible loss of energy caused by the viscous forces of the fluid on the surface of the pump [15]. Final form of the One-Dimensional Wave Equation describing forces propagating along a series of Sucker Rods: v OQtu du du _ Ox” Ot Ot ~ Where: — C - is a fixed non-negative ...
    ... A sucker rod pump is no more than a cylinder, or tube, consisting of two sections or chambers. One section is stationary or secured to the tubing. The other section travels with the sucker rod string. There are usually two valves working with these sections taking turns opening and closing. The ...
    ... number of revolutions of the drive motor. It has two shafts connected to each other by a reduction gear system. The rear shaft is equipped with a V-belt pulley through which the gearbox is connected to the motor. The front shaft of the gearbox carrles two arms with counterweights to which the drive ...