Lichens as bioindicators of air quality in Dimitrovgrad (South-Eastern Serbia)

Air pollution detection in Dimitrovgrad has not been done yet. In this work different lichen have been used as a bioindication to establish different air pollution levels. At 18 investigated points 22 lichen taxa have been found. Using the Index of Atmospheric Purity (IAP) it has been found that there are 3 different air pollution zones in Dimitrovgrad: 'lichen desert', 'transitional' and 'normal zone'. The most sensitive lichen taxa in Dimitrovgrad are Evernia prunastra, Ochrolechia pallescens, Parmelia sulcata, and Physcia tenella and the most tolerant are Phaeophyscia orbicularis, Physcia adscendens, Physconia distorta, Physconia grisea, and Xanthoria parietina.

Migrant crisis in public discourse of Serbia: informative websites and users’ comments

Предмет овог рада је мигрантска криза у јавном дискурсу Србије, односно медијске репрезентације мигрантске кризе на сајтовима водећих штампаних медија у Србији. Дискурс о овој теми биће анализиран посредством анализе образаца представљања којима су се служили медији. Истраживањем су обухваћени текстови новинара и текстови које производе читаоци на сајтовима медија у узорку. Репрезентација је одређена као процес конструкције значења и осмишљавања друштвене стварности употребом специфичних језичких образаца у дискурсу. У складу са теоријом социјалног конструкционизма, у раду се указује на улогу медија као важних институција у обликовању погледа на свет, стварању и преношењу значења, идеја, уверења и афеката. Имајући у виду да је у технолошки промењеном и комуникацијски унапређеном окружењу промењен и степен активности медијске публике, у обзир су узети и коментари читалаца традиционалних штампаних медија на вебу. Рад је концептуално осмишљен кроз два дела, теоријски и истраживачки део. У првом делу рада полази се од указивања на близак и међузависан однос дискурса и репрезентација друштвеног живота које дају смисао и значење друштвеним појавама. Осим постављања темеља рада у контекст социјално-конструкционистичког процеса и указивања на улогу медија у борби за наметање одређене верзије стварности у симболичком пољу културе, у раду се разматрају и нове улоге медијских корисника. Овде је пажња посвећена проблематици односа између професионалних комуникатора и комуникатора аматера, читалаца сајтова који све чешће реагују на текстове новинара. Имајући у виду да се медијска екологија променила, а са њом и положај публике, основни истраживачки циљ је испитивање произведених значења о мигрантској кризи и мигрантима у новинарским и коментаторским текстовима на сајтовима три најутицајнија медија у Србији: Блиц, Политика и Курир. На основу поређења наратива у ова два комуникацијска тока, намера је била да се утврди да ли постоји хетерогеност, разноврсност гласова у медијском дискурсу. Основна хипотеза у истраживању је била: Постоје разлике у дискурзивном конструкту (у говору) о мигрантима између новинарских и коментаторских текстова на информативним веб сајтовима дневних новина. Показатељи на основу којих су упоређене значењске целине створене у текстовима новинара и коментатора су: обрасци номинације, референтни и предикативни обрасци, употреба топоса (аргумената) и употреба стратегије колективизације и агрегације. На ове језичке стратегије у медијском представљању друштвених група указала је Рут Водак (Ruth Wodak, 2001) у оквиру социоисторијског приступа критичкој анализи дискурса. Узорак истраживања чинили су сајтови три водећа медија, Блиц, Политика и Курир, у чијим су оквирима анализирани текстови новинара и коментатора. Истраживањем је обухваћен сваки понедељак током 2015. и 2017. године. Од метода је коришћена анализа садржаја и критичка анализа дискурса како би се слика о мигрантима и мигрантској кризи довела у везу са друштвеним, политичким, економским и културним контекстом Србије. Резултати су показали да постоји статистички значајна разлика између текстова новинара и коментатора на сајтовима Политике и Курира у односу на номинативну, референтну, предикативну, аргументативну и агрегативну димензију, док та разлика није утврђена као значајна у односу на употребу колективистичког стила приказивања миграната и избеглица. Под номинативним, референтним и предикативним стратегијама представљања подразумевају се обрасци именовања, додавање одређених особина и квалитета појединцима и групама у медијском дискурсу. Стратегијом топоса или аргумената изражени ставови се потврђују, оправдавају и учвршћују у дискурсу. Агрегативна стратегија заснива се на употреби бројева и статистике у представљању миграната, а колективистичком стратегијом мигранти се сагледавају као група уједначених способности, особина, квалитета, мотива. У раду је, осим тога, указано и на статистички значајну разлику између три сајта у узорку у погледу истих показатеља и добијене су разлике у референтним, предикативним и аргументативним категоријама, док у односу на обрасце именовања, присуство агрегације и колективизације у Блицу, Политици и Куриру није забележена значајнија разлика. Закључак на који наводе резултати истраживања односи се на постојање тенденције медија да се привидно различитим конструкцијским моделима оствари хомогенизација мишљења, афеката и понашања публике према мигрантима, избеглицама и кризи, која је захватила цео свет. Изабране језичке стратегије, као механизми акредитације политичких и идеолошких циљева, неповољно и на неодговарајући начин представљају ову осетљиву групу људи, а медијски корисници ретко користе прилику да створе суштински другачија значења, већ се користе негативним схемама сагледавања других вођени ирационалним уверењима, страхом и ксенофобијом. У таквом односу фактора и актера у пољу јавног комуницирања, намеће се потреба и обавеза да се и медији и њихова публика оспособе да критички и самостално приступају производњи и употреби значења, ослобођени негативних модела из прошлости и идеолошких, политичких и комерцијалних притисака, уз уважавање универзалних људских права и принципа толеранције и сарадње у међукултурном сусрету.The subject of this paper is the migrant crisis in the public discourse of Serbia, specifically the media representation of the migrant crisis on the websites of the leading print media in Serbia. The discourse on this topic will be analyzed through the analysis of presentation patterns used by the media. Also, the research included both texts of journalist and texts produced by readers on the media sites presented in the sample. Representation has been defined as the process of constructing meaning and designing social reality by using specific linguistic patterns in discourse. In accordance with the theory of social constructivism, the paper indicates the role of the media as important institutions in shaping the worldview, creating and conveying meanings, ideas, beliefs and affects. Taking into consideration that in the technologically changed and communicatively improved environment the level of activity of media audience has also changed, the comments of the readers of traditional print media on the web have also been taken into account. The paper is conceptually designed through two parts, the theoretical part and the research part. The first part of the paper starts by pointing out the close and interdependent relationship of discourse and the representations of social life that bring meaning and significance to social phenomena. In addition to laying the foundation of the paper in the context of the social-constructionist process and pointing out the media role in the struggle to impose a certain version of reality in the symbolic field of culture, the new roles of media users have also been considered in the paper. Here, the attention is focused on the issue of the relationship between professional communicators and amateur communicators, site readers who have been increasingly reacting to the texts of journalists. Keeping in mind that both the media ecology and the position of audience have changed, the primary research goal is to examine the meanings produced about the migrant crisis and migrants in journalistic and commentary texts on the websites of the three most influential media in Serbia: Blic, Politika and Kurir. Based on the comparison of the narratives in these two communication flows, the intention was to determine whether there is heterogeneity, the diversity of voices in media discourse. The main hypothesis in the research was: There are differences in the discursive construct (in speech) about migrants between journalistic and commentary texts on the informative websites of daily newspapers. The indicators on the basis of which the semantic units produced in the texts of journalists and commentators were compared are the following: nomination patterns, reference and predicative patterns, the use of topos (arguments) and the use of collectivization and aggregation strategies. Ruth Wodak (2001) pointed out these language strategies in the media representation of social groups within the framework of the socio-historical approach to critical discourse analysis. Furthermore, the research sample consisted of the websites of the three leading media, Blic, Politika and Kurir, within which the texts of journalists and commentators were analyzed. The research included every Monday during 2015 and 2017. Content analysis and critical discourse analysis were the methods used in order to connect the image of migrants and the migrant crisis with the social, political, economic and cultural context of Serbia. Also, the results indicated that there is a statistically significant difference between the texts of journalists and commentators on the websites of Politika and Kurir in relation to the nominative, reference, predicative, argumentative and aggregative dimension, while this difference was not regarded as significant in relation to the use of collectivist representation style of migrants and refugees. Nominative, reference and predicative representation strategies denote the patterns of naming, adding certain characteristics and qualities to individuals and groups in media discourse. The expressed attitudes are being confirmed, justified and strengthened in the discourse by the strategy of topos or arguments, while the aggregation strategy is based on the use of numbers and statistics in the representation of migrants, and the collectivist strategy regards migrants as a group of uniform abilities, characteristics, qualities and motives. Moreover, the paper suggested the statistically significant difference between the three websites in the sample concerning the same indicators and the differences obtained in the reference, predicative and argumentative categories, while in relation to the patterns of naming, the presence of aggregation and collectivization in Blic, Politika and Kurir no significant difference was noticed. The conclusion drawn from the results of the research refers to the existence of the tendency of the media to achieve the homogenization of public opinions, affects and the audience behavior towards migrants, refugees and the crisis, which has affected the entire world, by seemingly different construction models. Selected language strategies, as well as the mechanisms for accrediting political and ideological goals represent this group of people in an unfavorable and inappropriate manner, while media users rarely use the opportunity to create fundamentally different meanings and rather use the negative schemes of perceiving others, led by irrational fears, beliefs and xenophobia. In such a relationship of factors and actors in the field of public communication, there is a need and obligation to enable both the media and their audience to critically and independently approach the production and use of meaning, free from the negative models from the past of ideological, political and commercial pressures, while respecting universal human rights and principles of tolerance and cooperation in the intercultural encounter

Study of age hardening effect during thermo-mechanical treatment on aluminium alloys

Ova doktorska disertacija obuhvatila je istraţivanja na aluminijumskim legurama iz serije 6000 (Al-Mg-Si legure, komercijalne aluminijumske legure EN AW-6060 i EN AW-6082). Na pomenutim legurama sprovedena je različita termomehanička obrada, nakon čega je ispitivan uticaj reţima prerade na mehanička, fizička, toplotna i strukturna svojstva. Ispitivanja su raĎena u cilju karakterizacije ispitivanih legura i sagledavanja uticaja prisutnih legirajućih elemenata (hemijskog sastava) na njihove strukturne, mehaničke, fizičke i toplotne karakteristike čime je dat i odreĎeni naučni i stručni doprinos boljem poznavanju ispitivanih Al-Mg-Si legura nakon starenja (prirodnog i veštačkog), kao i nakon termomehaničke obrade koja je sprovedena u cilju proučavanja njenog uticaja na efekat ojačavanja starenjem. Ciljevi istraţivanja usmerili su ovu disertaciju tako da doprinese boljem poznavanju uticaja reţima primenjene termomehaničke obrade na strukturu i osobine ispitivanih Al-Mg-Si legura, što će uz nesumnjiv teorijski doprinos omogućiti i proširenje njihove primene u najsavremenijim industrijama, gde je trenutno velika potraţnja za materijalima sa aluminijumskom osnovom sa poboljšanim osobinama. Doktorska disertacija je podeljena u osam poglavlja. U uvodnom delu dat je kratak osvrt na veliku potraţnju u industriji u poslednjim decenijama za materijalima koji po odreĎenim osobinama mogu zameniti materijale iz oblasti crne metalurgije, s obzirom na to da njihova proizvodnja iziskuje veliku potrošnju energije i dovodi do zagaĎivanja ţivotne sredine, kao i na ulogu aluminijuma i njegovih legura u ovom domenu. Osnovne napomene o aluminijumu i legurama na njegovoj osnovi, uz kratak osvrt na primenljivost ovih legura u industriji, kao i kratak opis uticaja postupaka prerada na strukturu i karakteristike aluminijuma i njegovih legura prikazan je u drugom poglavlju. U trećem poglavlju opisane su osnovne teorijske postavke i uslovi za pojavu precipitacionog ili taloţnog ojačavanja (ojačavanja starenjem), kao jedne od najčešće korišćenih metoda za poboljšanje osobina kod aluminijumskih legura, pa i kod Al-Mg-Si legura. U četvrtom poglavlju predstavljeni su postojeći publikovani rezultati o karakterizaciji legura sistema Al-Mg-Si. Ciljevi istraţivanja prikazani su u petom poglavlju. U šestom poglavlju opisan je način izvoĎenja eksperimenata i dat je uvid u metode kojima je moguće izvršiti potrebna merenja i karakterizaciju dobijenih uzoraka. Za karakterizaciju legura korišćeno je više savremenih, standardizovanih metoda i tehnika. Eksperimetalni rezultati svih izvršenih ispitivanja sistematizovani su i izneti u sedmom poglavlju ovog rada uz odgovarajuću analizu i diskusiju rezultata. Legure EN AW-6060 i EN AW- 6082 dobijene su od strane „Al-Cu metali― firme iz Niša u obliku flahova i izraĎene su po standardima koji diktiraju parametre izrade. Kompletan materijal je podvrgnut ţarenju radi uklanjanja fabričke strukture i dobijanja najmekšeg stanja (temper O). Ovo ţarenje je uraĎeno na temperaturi od 550°C u trajanju od 6 h. Nakon uklanjanja fabričke strukture, izdvojeni su uzorci u setove i svaki od setova je bio podvrgnut različitoj termičkoj ili termomehaničkoj obradi. U prvom setu cilj je bio dobijanje početnih uzoraka koji su korišćeni za poreĎenje, stoga je grupa uzoraka podvrgnuta rastvornom ţarenju u trajanju od 1 h na temperaturi od 550°C i kaljenju u vodi sa ledom radi dobijanja presićenog čvrstog rastvora (temper W). Zatim je pristupljeno isptivanju parametara koji definišu precipitaciono ojačavanje (starenje). U ovom setu ispitivan je uticaj temperature rastvornog ţarenja, pa su stoga uzorci podvrgavani različitim temperaturama rastvornog ţarenja (510°C, 530°C, 550°C, 570°C, 590°C), nakon čega su uzorci ispitivani odmah nakon kaljenja, nepotpunog starenja i potpunog starenja...This doctoral dissertation included the investigation of aluminium alloys from 6000 series (Al-Mg-Si alloys, commercial aluminium alloys EN AW-6060 and EN AW-6082). Various thermomechanical treatments (TMT) were applied to these alloys, after which the influence of these regimes on the mechanical, physical, thermal and structural properties was examined. The investigations were performed in order to characterize the alloys and to investigate the influence of alloying elements (chemical composition) on structural, mechanical, physical and thermal properties. These investigations also gave a certain scientific and professional contribution to better understand the investigated Al-Mg-Si alloys after ageing (natural or artificial), as well as after the thermomechanical treatment that was applied in order to study its effect on the precipitation hardening process. The research aim in this doctoral dissertation was to contribute to a better understanding of the influence of applied thermomechanical treatment on the structure and properties of the investigated Al-Mg-Si alloys. This will undoubtedly give the theoretical contribution and the expansion of the use of these alloys in modern industry, where currently there is a high demand for aluminium-based materials with improved properties. The doctoral dissertation is divided into eight chapters. The introductory section gives a brief overview of the great demand in the industry for materials that can replace materials in the field of ferrous metallurgy, since the production of ferrous metals requires high energy consumption and leads to environmental pollution, as well as to the role of aluminium and its alloys in this domain. Basic notes on aluminium and its alloys, with a brief overview of the applicability of these alloys to the industry, as well as a brief description of the impact of processing operations on the structure and characteristics of aluminium and its alloys, are presented in Chapter Two. The third chapter describes the basic theoretical assumptions and conditions for the appearance of precipitation hardening or ageing as one of the most commonly used methods for improving the properties of aluminium alloys including the Al-Mg-Si alloys. Chapter 4 presents the published results on the characterization of Al-Mg-Si alloys. The research goals are presented in Chapter Five. The sixth chapter describes the method of performing the experiments and gives an insight into the methods that can be used to perform the necessary measurements and characterization of the obtained samples. Several modern, standardized methods and techniques have been used to characterize the alloys. The experimental results of all the tests performed are systematized and presented in the seventh chapter of this paper with appropriate analysis and discussion of the results. The alloys EN AW-6060 and EN AW-6082 were produced and delivered by the company ―Al-Cu metali‖ in the form of rectangular bars. All necessary standards that dictate the manufacturing parameters were followed during the production. The received material was subjected to annealing to remove the fabricated state and to obtain the lowest strength and highest ductility (temper O). This annealing was done at a temperature of 550°C for a period of six hours. After obtaining adequate temper, the bars were cut to the appropriate dimensions and the samples of both alloys in this state were separated to be subjected to different HT or TMT. Firstly, the goal was to obtain the initial samples which would later be used for comparison in every other experiment. The samples of both alloys were subjected to solution heat treatment at 550°C and then quenched in ice water in order to obtain a super saturated solid solution (αssss) (temper W). After that, investigation of the parameters that define the ageing treatment was started. In this set of samples, the influence of the solutionizing temperature was examined, and in this setsamples were subjected to different solutionizing temperatures (510°C, 530°C, 550°C, 570°C, 590°C), where the samples were examined immediately after quenching, after partial ageing and after complete ageing. Results of these experiments were later used as a guide in defining the optimal solution heat treatment temperature

Procena usamljenosti studenata sa oštećenjem vida

Background/Aim. Loneliness is becoming more frequent, especially in young people. Some authors believe that visual impairments increase the risk of loneliness. Empirical data on its manifestation in persons with visual impairments are contradictory. The aim of this research was to determine the degree of loneliness in students with visual impairments and their peers from general population. Methods. A comparative research was conducted on a sample consisting of 36 visually impaired students and 101 students without visual impairments (control group). Students with visual impairments were divided into 3 subgroups with regard to the degree of visual impairments (students with low vision, legally blind, and totally blind students). University of California Los Angeles Loneliness Scale (which assesses the general loneliness) and Social and Emotional Loneliness Scale (which assesses social loneliness, family loneliness, and romantic loneliness) were used in our investigation. Results. The results showed that the general loneliness was significantly lower in the group of students with visual impairments than in the control group (t = 2.121; p = 0.036). There were no significant differences in the Social and Emotional Loneliness Scale between the group with visual impairments and the control group. No significant differences were determined in the level of loneliness among students with a different degree of visual impairments. There are significant differences in the manifestation level of social loneliness, family loneliness, and romantic loneliness (Wilk's lambda = 0.604; p ≤ 0.000) in the group of students with visual impairments. Romantic loneliness was manifested the most, followed by social loneliness, while family loneliness was the least manifested. Conclusion. With regard to the results of our research, visual impairment alone is not a crucial factor of loneliness in students with visual impairments. Further studies on protective factors of loneliness can contribute to its prevention in young people with visual impairments.Uvod/Cilj. Usamljenost je sve učestalija, posebno u populaciji mladih. Neki autori smatraju da oštećenje vida povećava rizik od usamljenosti. Empirijski podaci o ispoljenosti kod osoba sa oštećenjem vida su kontradiktorni. Cilj našeg istraživanja bio je utvrđivanje stepena usamljenosti kod studenata sa oštećenjem vida i njihovih vršnjaka iz opšte populacije. Metode. Komparativno istraživanje je obavljeno na uzorku koji je činilo 36 studenata sa oštećenjem vida i 101 studenata bez oštećenja vida (kontrolna grupa). Na osnovu stepena oštećenja vida, studenti sa oštećenjem vida bili su podeljeni u tri podgrupe (slabovidi, praktično slepi i potpuno slepi). U našem istraživanju korišćeni su University of California Los Angeles Loneliness Scale (za procenu opšte usamljenosti) i Skala socijalne i emocionalne usamljenosti (za procenu socijalne, porodične i usamljenosti u ljubavi). Rezultati. Analiza rezultata je pokazala da je opšta usamljenost bila značajno manja u grupi studenata sa oštećenjem vida nego u kontrolnoj grupi (t = 2.121; p = 0.036). Na Skali socijalne i emocionalne usamljenosti nije utvrđena statistički značajna razlika između grupe studenata sa oštećenjem vida i kontrolne grupe. Takođe, nije utvrđena značajna razlika u nivou usamljenosti između studenata sa različitim stepenom oštećenja vida. U grupi studenata sa oštećenjem vida postojala je značajna razlika u stepenu ispoljenosti socijalne usamljenosti, usamljenosti u porodici i usamljenosti u ljubavi (Wilk's lambda = 0.604; p ≤ 0.000). Najviše je bilo ispoljena usamljenost u ljubavi, sledi socijalna usamljenost, dok je usamljenost u porodici bila najmanja. Zaključak. Prema rezultatima našeg istraživanja, samo oštećenje vida nije presudni činilac usamljenosti kod studenata sa oštećenjem vida. Buduća istraživanja protektivnih faktora usamljenosti mogu doprineti prevenciji ove pojave kod mladih sa oštećenjem vida

Physico-chemical characterization of mixed-ligand complexes of Mn(III) based on the acetylacetonate and maleic acid and its hydroxylamine derivative

Two new Mn(III) mixed-ligand complexes with two acetylacetonate (acac) ligands and one maleate ligand and its hydroxylamine derivative of the general formula [Mn(C5H7O2)2L] were prepared. Their structure was established by using elemental analysis, FTIR and UV/VIS spectroscopic methods, as well as magnetic measurement. Replacement of the acetylacetonate ligand by the corresponding acid ligand has been confirmed in Mn(III) acetylacetonate. Based on the obtained experimental data and literature indications, structural formulae to these compounds were assigned

Biocompatibility and cytotoxicity study of nanophotonic rigid gas permeable contact lens material

Since materials on nanoscale have different characteristics from materials on macro scale their biocompatibility should be precisely and specifically investigated. Fullerenes, the third carbon allotrope, are one of the most used nanomaterials. The least stable and the most common is fullerene C-60. One of the main disadvantages of fullerene is its low solubility in water. In order to make it soluble, it must be functionalized with polar groups such as -OH and -COOH. From all the water soluble fullerenes the most important ones are those with -OH groups attached named fullerols. We have developed new materials for contact lenses by adding fullerene (C-60) and fullerol (C-60(OH)(24)) into PMMA. The aim of our investigation was to compare the influences of those materials on aqueous solutions similar to tear film. For the analysis of the solutions we used opto-magnetic imaging and IR spectroscopy. The acquired spectrums were commented and compared with the standard contact lens material, which was analyzed by the same methods. The ISO 10993 cytotoxicity test on extract of nanophotonic material with incorporated C-60 was done as well. This research contributes to better understanding of the biocompatibility of new rigid gas permeable contact lens materials

Computation Method in Failure Analysis of Mechanically Fastened Joints at Layered Composites

This paper considers a computation method in failure analysis of layered composites containing pin-loaded holes. The investigation is focused on developing a reliable computation procedure to analyze initial failure load for pin-loaded holes at layered composite structures. Finite element method (FEM) is used to determine stress distribution around the fastener hole. Combining Chang-Scott-Springer characteristic curve model and Tsai-Wu initial failure criterion are used to determine joint failure. Special attention in this work is paid to pin-load distributions and its effect on the load level of failure and its location. In previous work initial failure analysis was carried out using cosine distribution between pin/lug mechanically fastened joint. Here contact finite element pin/lug model is analysed. The influence of stacking sequences of layered composites containing pin-loaded holes is also investigated. Special attention is paid to failure load and mode analyses in composites with stacking sequence [0/(+/-45)(3)/90(3)](s). The computation results are compared with available experimental results. Good correlations between computation and experimental results are obtained

Comparison of Box-Behnken, Face Central Composite and Full Factorial Designs in Optimization of Hempseed Oil Extraction by n-Hexane: a Case Study

Statistical multivariate methods like Box-Behnken, face central composite and full factorial designs (BBD, FCCD and FFD, respectively) in combination with the response surface methodology (RSM) were compared when applied in modeling and optimization of the hempseed oil (HSO) extraction by n-hexane. The effects of solvent-to-seed ratio, operation temperature and extraction time on HSO yield were investigated at the solvent-to-seed ratio of 3:1, 6.5:1 or 10:1 mL/g, the extraction temperature of 20, 45 or 70 °C and the extraction time of 5, 10 or 15 min. All three methods were efficient in the statistical modeling and optimization of the influential process variables and led to almost the same optimal process conditions and predicted HSO yield. Having better statistical performances and being economically advantageous over the FFD with repetition, the BBD or FCCD combined with the RSM is recommended for the optimization of liquid-solid extraction processes

Ispitivanje uticaja nanofotoničnih tvrdih gaspropusnih kontaktnih sočiva na fiziološki rastvor akvafotomikom i opto-magnetnom imidžing spektroskopijom

Contact lenses represent biomaterials whose main purpose is to correct the specific refractive anomaly of the eye. Since the visible light on its way to the perceptive part of the eye has to pass through the contact lens, the characteristics of the materials can significantly modify it. Biocompatibility of the lens surface is one of the most important issues in achieving contact lens wear without problems. We have developed new nanophotonic contact lens materials by adding nanoparticles of fullerene and their derivatives into standard PMMA RGP material. The aim of our investigation was to compare the influences of these materials on saline which is similar to tear film. We used NIR spectroscopy based on 12 vibration modes, called Aquaphotomics and Opto-magnetic imaging (OMI) spectroscopy as methods for characterizing the samples. The acquired spectrums were commented and compared with the standard contact lens material, which was analyzed by the same method.Kontaktna sočiva predstavljaju biomaterijale čija je glavna svrha ispravljanje specifičnih refraktivnih anomalija oka. S obzirom da vidljiva svetlost na svom putu do perceptivnog dela oka mora da prođe kroz kontaktno sočivo, karakteristike materijala mogu značajno da je izmene. Biokompatibilnost površine sočiva je jedno od najvažnijih pitanja u postizanju nošenja kontaktnih sočiva bez problema. Razvijeni su novi nanofotonični materijali za kontaktna sočiva dodavanjem nanočestica fulerena i njihovih derivata u standardni PMMA materijal za tvrda gas propusna kontaktna sočiva. Cilj našeg istraživanja je bilo poređenje uticaja ovih materijala na fiziološki rastvor koji je sličan suznom filmu. Za karakterizaciju uzoraka koristili smo blisku infracrvenu spektroskopiju zasnovanu na 12 vibracionih modova, poznatiju kao Akvafotomika. Dobijeni spektri su komentarisani i upoređeni sa standardnim materijalom za kontaktna sočiva, koji je analiziran istom metodom

Fracture mechanics analysis of damaged turbine rotor discs using finite element method

This paper presents evaluation fracture mechanics parameters in low pressure turbine components. Critical locations such as keyway and dovetail area are experiencing stress concentration leading to crack initiation. Stress intensity factors were evaluated using the J-Integral approach available within ANSYS software code. The finite element method allowed the prediction of the point of crack initiation and the crack propagation using the orientations of the maximum principal stresses. Special attention in this investigation is focused to develop analytic expressions for stress intensity factors at critical location of low pressure steam turbine disc