INFLUENCE OF DOPAMINERGIC SYSTEM ON INTERNET ADDICTION

Internet addiction is a clinical anomaly with strong negative consequences on social, work-related, family, financial, and economic function of a person. It is regarded as a serious public health issue. The basic idea of this paper is to, based on the currently available body of research work on this topic, point out to neurobiological pathos of Internet addiction, and its connection to the dopaminergic system. Dopamine contains all physiological functions of neurotransmitters and it is a part of chatecholamine family. Five dopaminergic receptors (D1 - D5) belong to the super family of receptors related to G-protein. Through these receptors, dopamine achieves its roles: regulation of voluntary movement, regulation of center of pleasure, hormonal regulation, and regulation of hypertension. In order to recognize an Internet user as an addict, he or she needs to comply with the criteria suggested by the American Psychiatric Association (APA). Phenomenological, neurobiological, and pharmacological data indicates similarities in pathopsychology of substance addiction and pathological gambling, which are indirectly related to the similarity with the Internet addiction. Responding to stimuli from the game, addicts have shown more brain activity in the nape region, left dorsolateral, prefrontal cortex, and left parachipocampal gyrus than in the control group. After the six-week bupropion therapy, desire to play Internet and video games, the total duration of playing, and induced brain activity in dorsolateral prefrontal cortex are lowered with the addicts

3D animation applications in descriptive geometry teaching

The use of digital technology includes an interdisciplinary approach. The focus is on fusion of different media and genres into new forms of artistic expression as well as transcending the boundaries between art and education, the arts and research. Teaching descriptive geometry using animation softwares enables development of the ability of spatial representation, perception and understanding of space. The specific contribution is in the education by working with 3D animation for students of art and engineering field of technical - technological group of students. We emphasize the importance of dealing with design dynamically- generated form. Experimental design (freeform) presented on DVD includes: generating a surface with the two profiles as guidelines, generating free form using lattice deformers and generate free-form by the duplicating along curve tool. The key concept of dynamic geometry is to select the item which is then changed position and simutaneously you can see changes in the structure. This ability of movement is fundamentally improvement regard to the drawing on the paper or static CAD models. The movement in animation is captured by sequence of static pictures. If we have the form which changes during the time, we could observe these changes also sequentially. On this way, the form cloud be observed during the morphing in time, and each particular frame could be the base for further development.be observed during the morphing in time, and each particular frame could be the base for further development

Synthesis, characterization and sorption properties of bentonite modified by tetraalkylammonium ions

Ovaj rad je posvećen sintezi organobentonita (OB) dobijenih modifikacijom kvaternernim alkilamonijum katjonima (KAAK), karakterizaciji dobijenih uzoraka, ispitivanju njihovih adsorpcionih svojstava prema organskim i neorganskim zagađivačima prisutnim u otpadnim vodama tekstilne industrije, kao i utvrđivanju multifunkcionalnog adsorbensa koji bi usled posedovanja i hidrofilne i organofilne površine uspešno mogao biti upotrebljen prilikom tretmana otpadnih voda kompleksnog sastava Sintetisani OB dobijeni su od bentonitne gline sa lokaliteta Bogovina (Srbija). Polazni uzorak frakcije <74 μm je najpre Na–izmenjen (Na–B), a zatim modifikovan KAAK jonima. Modifikacijom su dobijene dve serije organobentonita. U prvoj seriji je korišćen heksadeciltrimetilamonijum (HDTMA) bromid, pri čemu količina odgovara vrednostima Kizm=0,2–3,0 (gde je Kizm broj koji pokazuje odnos KAAK jona prema vrednosti kapaicteta katjonske izmene). Druga sereija je dobijena modifikacijom bentonita KAAK različite dužine alkil niza: HDTMA bromidom, dodeciltrimetilamonijum (DDTMA) bromidom i tetrametilamonijum (TMA) bromidom, pri čemu je Kizm=2,0. Dobijeni uzorci su označeni kao 0,2 HDTMA–B, 0,5 HDTMA–B, 1,0 HDTMA–B, 2,0 HDTMA–B, 3,0 HDTMA–B, 2,0 DDTMA–B, 2,0 TMA–B. Ispitivan je uticaj modifikacije na strukturu, teksturalna i adsorpciona svojstva bentonita. Hemijski sastav polaznog bentonita i Na–B je određen standardnom silikatnom analizom, dok je procena udela organske faze kod OB izvršena žarenjem uzoraka na 800°C, čime je potvrđeno prisustvo organske faze čiji udeo raste sa porastom Kizm i sa porastom dužine alkil niza KAAK. Fazni sastav, teksturalna i morfološka svojstva Na–B i uzoraka OB određeni su korišćenjem XRD analize, IC analize, metodom fizisorpcije N2 i SEM mikroskopije. Utvrđeno je da primenjeni postupci modifikacije dovode isključivo do izmene katjona u međulamelarnom sloju smektita, dok modifikacija ne deluje na druge prateće minerale u bentonitu (kvarc, kalcit, feldspat). Kod uzoraka 0,2, 0,5 i 1,0 HDTMA–B na osnovu vrednosti d001 utvrđeno je da dolazi do formiranja monosloja, dvosloja i pseudo-tri molekulskog sloja HDTMA katjona, dok kod uzoraka sa Kizm=1,0-3,0 HDTMA–B unutar međusloja dolazi do formiranja organske faze za koju je pretpostavljeno da je delimično sastavljena od parafinskih slojeva. IC spektri uzoraka OB ukazuju na prisustvo tri nove trake koje potiču od vibracija metilenske grupe, što je još jedna potvrda ugradnje KAAK. Kod svih OB osim 2,0 TMA–B, utvrđeno je da sa povećanjem Kizm i dužine alkil niza KAAK dolazi do značajne promene teksturalnih svojstava u odnosu na polazni Na–B. Uočen je pad specifične površine materijla i prelazak mikro i mezoporoznog materijala u gotovo potpuno neporozan. Sa druge strane, 2,0 TMA–B i Na–B imaju slične teksturalne osobine, što je posledica ugradnje kratkolančanog katjona TMA u obliku „pilara“, a posledica je stvaranje mikroporoznog materijala. Analizom SEM mikrofotografija snimljenih uzoraka analizirane HDTMA serije uočava se da svi izorci zadržavaju slojevitu strukturu filosilikata...The synthesis of organo-bentonites (OB) obtained by modification with quaternary alkylammonium cations (QAAC), their characterization and evaluation of their efficiency as adsorbents for organic and inorganic aqueous pollutants was investigated in this work. Particular attention was dedicated to the removal of pollutants from textile industry effluents, and obtainment of a multifunctional adsorbent that incorporates both hydrophilic and hydrophobic surfaces, which can be successfully applied in the purification of wastewaters with complex composition. The synthesized OBs were obtained from smectite containing clay bentonite from Bogovina basin (Serbia). The starting material, consisted of particles with diameters of up to 74μm, was submitted to Na-exchange (Na-B), and subsequent modification with QAAC ions. Two series of OBs were obtained in this manner. The first series was obtained using hexadecyltrimethylammonium (HDTMA) bromide. The amount of introduced HDTMA was expressed as Kexch=0,2–3,0, where the value of Kexch represents the ratio between QAAC ions and the cation exchange capacity of the clay. The second series was obtained by the bentonite modification using QAACs (Kexch=2,0) with different alkyl chain lengths: HDTMA bromide, dodecyltrimethylammonium (DDTMA) bromide and tetramethylammonium (TMA) bromide. The samples were denoted as 0,2 HDTMA–B, 0,5 HDTMA–B, 1,0 HDTMA–B, 2,0 HDTMA–B i 3,0 HDTMA–B, 2,0 DDTMA–B, 2,0 TMA–B. The influence of the modification on the structural, textural and adsorption properties of bentonite was investigated. The chemical compositions of the starting and Na-exchanged bentonite were determined by standard silicate analysis, and the fraction of the organic phase in the samples was estimated after calcination at 800°C. The increasing presence of the organic phase with increased Kexch or QAAC alkyl chain length was confirmed. The phase composition, textural and morphological properties of the Na-B and OB samples were determined by XRD and IR analyses, N2 physisorption and SEM microscopy. It was found that the applied modification procedures resulted in the exclusive exchange of cations from the smectite interlamellar region, with no impact on the accompanying minerals present in bentonite (quartz, calcite, feldspar). In the case of 0,2, 0,5 i 1,0 HDTMA–B samples, it was concluded from the d001 values that the consequence of the modification was the formation of mono-, bi- or pseudotrimolecular HDTMA layers. As for the 1,0–3,0 HDTMA-B samples it is presumed that the formation of organic phase occurred within the interlamellar region, which is probably partially consisted of paraffin layers. The IR spectra of the OBs exhibited the occurrence of three new bands corresponding to methyl group vibrations, which is another proof of the incorporation of QAACs. For all OB samples, except for the 2,0 TMA–B, was established that the increase in the Kexch values and alkyl chain lengths lead to significant changes in the textural properties comparing to those of the starting Na-B material. The decrease in the specific surface was observed, and the starting micro/mesoporous material was turned almost completely nonporous. On the other hand, the 2,0 TMA–B and Na-B exhibited similar textural properties, which is a consequence of the incorporation of short-alkylchained TMA cations in the form of pillars resulting in a microporous material The analysis of the SEM micrographs of the HDTMA sample series it was observed that all the samples retained characteristic phylosilicate layered structure..

Zn- A nd (Mn, Zn)-substituted versus unsubstituted magnetite nanoparticles: Structural, magnetic and hyperthermic properties

In this work, we studied structural and magnetic properties of 18 nm sized Zn-substituted magnetite, 28 nm sized unsubstituted and 17 nm sized (Mn, Zn)-substituted iron oxide nanoparticles, synthesized by thermal decomposition method. Their features were examined by analyzing the X-ray diffraction data, 57Fe Mössbauer spectra and magnetization measurements by SQUID interferometer. The microstructure was inspected comparing the different size and strain broadening models incorporated into Fullprof software. In terms of crystallinity and size dispersion, applied synthesis protocol shows superiority over decomposition of iron oleate and the co-precipitation synthesis route. The saturation magnetization at T = 5 K was found to be within the M S = 91.2-98.6 A m2kg-1 range, while at 300 K M S of pure and Zn-substituted Fe3O4 nanoparticles is 83.6 and 86.2 A m2kg-1, respectively. Effective magnetic anisotropy constant K eff, estimated under slow measurements by SQUID, is below 20 kJ m-3 in all three samples. Some preliminary measurements of the magnetic hyperthermia performance, expressed via specific absorption rate value showed that the best heating performances were displayed by 18 nm sized oleic acid-coated Zn0.13Fe2.87O4 cubo-octahedrons with SAR ≅ 425 W/gFe at H 0 = 20 kA m-1 and f = 228 kHz.Fil: Jović Orsini, Nataša. University of Belgrade; SerbiaFil: Milić, Mirjana. University of Belgrade; SerbiaFil: Torres Molina, Teobaldo Enrique. Universidad de Zaragoza. Instituto de Nanociencia de Aragón; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin

A model of road traffic as a resource risk loss in the elderly population of Croatia

Background and Purpose: Use of the road traffic resource inevitably leads to significant human andmaterial losses. Thus, the standardized death rate among older people (65years) in the European Union was 19.8 in 2000 and 11.9 in 2011. A model is proposed of human loss through RTA to establish the main resource losses and major risk loss factors for victimization of the elderly population (65years), as compared to the risk prone young population (18–24 years). Materials andMethods:Data onRTA in Croatia are obtained fromthe official government bulletin for road safety of the Ministry of the Interior for the period 2000–2011. Minimum and maximum number of victims and mean expected loss are used for determination of environmental risks and risk proneness. Results and Conclusions: A comparative victimization analysis for Croatia for the period 2000–2011 shows significant losses for mild and severe injury to younger RT participants, increased mild injury to elderly drivers, and increased severe injury among elderly pedestrians.Risk ismostly expressed in fatal RTA for younger participantswith risk proneness of 32.4%. The most exposed RT users are: severely injured elderly drivers with unprofitable and profitable risks between 32.8 % and 50.9 %, fatally injured elderly drivers with unprofitable and profitable risks between 43.2 % and 66.1 %, and fatally injured elderly pedestrians with unprofitable and profitable risks between 93.9%and 86.3%. These facts demand preventive actions for these users on the side of car and road designers and traffic educators as well

Interfacial Polarization and Dielectric Properties of Epoxy/Graphite Flakes Composites

Dielectric properties of composites based on bisphenol-A-epoxy resin loaded with various content of graphite flakes (GF) have been studied. The dielectric permeability, tangent loss and ac conductivity have been examined in wide temperature (170 – 370 K) and frequency (20 Hz – 200 kHz) range. In composites loaded with GF flakes up to 10 wt.%, the dominant conduction mechanism is tunneling of electrons, while loading of 15 wt.% gives rise to electron conduction through direct contacts between fillers. Dielectric properties of composites are largely determined by the nature of the filler/matrix interface, the filler surface area and the inherent conductivity of the fillers. At low electric field frequencies, dominates socalled interfacial (or space charge) polarization due to accumulation of free charges at the interfaces between two phases (filler and matrix), which differ in electrical conductivity.Influence of the filler surface chemistry have been studied for composites loaded with 5 wt.% graphite flakes obtained: (i) under wet milling, without (GF) or with (GF-Tr100x) adding Triton-100x as a surfactant, or (ii) under dry milling in the presence of KOH (GF-KOH). The surface treatment with KOH notable increased dielectric constant of the epoxy/GF-KOH5 composite, keeping low tangent loss, comparable to the counterpart, the epoxy/GF5 composite

Influence of air pollution on hospital admissions for cardiovascular and respiratory diseases in Niš, Serbia

Background/Aim. In studies that investigate the health effects of short-term air pollution exposure, population-wide changes in acute outcomes such as mortality, hospital admissions and healthcare visits are linked to short-term variations in ambient pollutant concentrations. The aim of this study was to estimate the association between daily outdoor black smoke and sulphur dioxide levels and hospital admissions for cardiovascular and respiratory diseases in Niš, within a period 2001-2005. Methods. A time series analysis was performed using separated regression models for each pollutant and disease group, by age groups and population as a whole. The effects of copollutant, meteorological factors and cyclic oscillations in hospitalization numbers were controlled. Results. A significant increase in hospital admissions was associated with a 10 μg/m3 increase in the concentration of black smoke, for cardiovascular diseases: 3.14% (&lt; 0.01) in children and youth under 19 years of age, 1.85% (&lt; 0.001) in 19-64 age group, and 0.84% (&lt; 0.05) in all ages, and for respiratory diseases: 1.77% (&lt; 0.05) in 19-64 age group, and 0.91% (&lt; 0.05) in all ages. The effects on hospitalizations for respiratory diseases in children and youth under 19 years of age, and for cardiovascular and respiratory diseases in the elderly were not statistically significant. The increase of sulphur dioxide level was associated with the increased number of hospitalizations, for both cardiovascular and respiratory diseases in all age groups, but the influence was not statistically significant. Conclusion. Outdoor pollutants concentrations in urban area of Niš were below regulated limit values during most of the investigated period days but it is shown that even such a level of pollution has a significant effect on hospital admissions for cardiovascular and respiratory diseases

Variability of structural and magnetic properties of nanocrystalline spinel ferrites

Nanocrystalline spinel ferrites, with the general formula MFe2O4 (M is a divalent cation) are an important class of nanostructured materials with their potential in ceramic, electrochemical, magnetic, ferroelectric, catalytic and biomedical applications. Using a low temperature synthesis of such materials it is possible to obtain ultra fine particles. The crystal structure, microstructure and magnetic properties of series of nanocrystalline spinel ferrites have been studied by XRD, HRTEM, Mössbauer spectroscopy and SQUID measurements. The Rietveld analysis of the powder diffraction data have been performed (using Fullprof software) to obtain quantitative microstructural information (e.g. the cation distribution, the crystallite size, microstrain). More sophisticated models have been used to explain magnetic behavior of an assembly of nanostructured particles, which include microscopic mechanisms such as spin disorder, surface contributions and the presence of interparticle interactions (exchange and/or dipolar). The saturation magnetization of investigated nanostructural vs. bulk spinel ferrites is discussed in term of a competition between the site exchange of cations and the spin canting phenomena. For a selected example, the variation in the particle anisotropy energy, extracted from the magnetic measurements in high and low external magnetic field, is well describe accounting for the interparticle interaction and the surface effects on the energy barrier.I Serbian Ceramic Society Conference : 1CSCS-2011 : program and the book of abstracts; March 17-18, 2011; Belgrad

The Luminescent Properties of Yttrium Oxyapatite Doped with Eu3+ ions

The structural and luminescent properties of Ca2Y8(SiO4)(6)O-2 (CYS) silicate based oxyapatite doped with Eu3+ ions have been reported in this paper. The sample was synthesized using reflux method assisted by urea subsequent degradation. Very specific, shell- and and rope-like morphologies were observed by SEM. The powder X-ray diffraction study revealed that the Eu3+ : CYS system crystallized in a hexagonal lattice structure (space group P63/m) characteristic of oxyapatite. In the host oxyapatite structure, a partial replacement of Ca2+ and Y3+ ions by luminescent active Eu3+ ions have been done, and its photoluminescent spectra were analyzed. The performed analysis indicate the presence of Eu3+ ions in both, nine-fold coordinated 4f, and seven-fold coordinated 6h sites, showing a slight shift towards the blue area in comparison to a typical spectra of other yttrium-silicate phases as hosts