Micromechanical properties and thermal stability of adhesives for optical fibers based on ethylene-vinyl acetate copolymer

Optička vlakna se koriste za prenos informacija u situacijama kada je potreban pouzdan sistem, a u pojedinim slučajevima potrebno je vlakna transportovati na kalemima i omogućiti kontrolisano i brzo odmotavanje vlakna sa kalema. Za fiskiranje vlakana u ovim situacijama koriste se adhezivi koji moraju da imaju definisana svojstva u pogledu adhezivnosti i starenja. Prikazana istraživanja daju novi pristup u ispitivanju adhezivnih efekata i sila između optičkih vlakana i adheziva, i u ovu svrhu razvijena je eksperimentalna metoda za brzo ispitivanje. Korišćeni su adhezivi na bazi kopolimera etilena i vinil-acetata (EVA) i polimernih blendi sa dodatkom poli(metil-metakrilata) (PMMA). Karakterizacija optičkih vlakana je vršena primenom optičke i skenirajuće elektronske mikroskopije u cilju ispitivanja morfologije; test na istezanje za utvrđivanje zatezne čvrstoće optičkog vlakna; nanoindentacije za utvrđivanje elastičnih svojstava zaštitne polimerne prevlake optičkog vlakna; infracrvene spektroskopije sa Furijeovom transformacijom (FTIR) za karakterizaciju hemijskog sastava polimerne prevlake optičkog vlakna, kao i dobijenih adheziva. Za ispitivanje adhezivnosti korišćeno je optičko vlakno sa najboljim mehaničkim svojstvima (optičko vlakno pod nazivom SFM 28+ corning). Na osnovu analize hemijskog sastava polimerne prevlake na optičkom vlaknu utvrđeno je da EVA ima zadovoljavajuću kompatibilnost sa završnom prevlakom što je otvorilo mogućnost razvoja adheziva baziranih na tom polimeru. U cilju poboljšanja termičke stabilnosti EVA kopolimera, korišćeni su i adhezivi na bazi EVA/PMMA polimernih blendi, gde je Elvax 410 korišćen kao EVA kopolimer sa boljom termičkom stabilnošću. Kompatibilizacija EVA/PMMA polimerne blende je izvedena polimerizacijom u masi preko slobodnih radikala, čime je dobijen sirovi adheziv s-EVA-g-PMMA. Kontrolisana „živa” polimerizacija je korišćena za kontrolu adhezivnosti i kompatibilizacije promenom dužine kalemljenih lanaca. Karakterizacija polimernih blendi je obuhvatala ispitivanje hemijske strukture, adhezivnih i termičkih svojstava u poređenju sa EVA kopolimerima i fizičkom polimernom blendom EVA/PMMA. Adhezioni test dva spojena vlakna je pokazao da je modifikacijom fizičke blende uspostavljena poboljšana adhezija. Optičkom mikroskopijom je utvrđen tip adhezionog loma koji je ukazivao na razliku u adhezivnosti korišćenih polimernih adheziva. Efekat kompatibilizacije je praćen putem optičke mikroskopije posmatranjem izdvajanja faza polimernih blendi i određivanjem ugla kvašenja optičkog vlakna. Ispitivana su svojstva adheziva nakon ubrzanog starenja na 60 °C tokom 60 i 120 sati...Optical fibers are used for transfer of information when the reliable system was required, and in some situations it is necessary to transport optical fibers on the drums and to enable controlled and fast unwinding from the drum. Adhesives used for fixation of the optical fiber in these situations need to have defined properties regarding to adhesiveness and age resistance. Presented research contributes new approach in investigating of adhesion effects and forces between the optical fibers and adhesive, and in that aim novel experimental method was developed for fast examination of mentioned effects. Ethylene-vinyl acetate copolymers were used (EVA) and the polymer blends with the addition of poly(methyl methacrylate) (PMMA). Characterization of optical fibers was performed by optical and scanning electron microscopy in the aim of morphology examination; by tensile test for tensile strength determination; nanoindentation to obtain elastic properties of final polymer coating of optical fiber; Furrier transformed infrared spectroscopy for characterization of chemical composition of polymer coating of optical fiber, as well as obtained adhesives. In testing of adhesiveness, optical fiber with outstanding mechanical properties was used (optical fiber denoted as SFM 28+ corning). Based on the analysis of chemical composition of final polymer coating of optical fiber, it was concluded that EVA have satisfied compatibility with the optical fiber final coating, what led to opportunity for developing adhesives based on mentioned copolymer. In the aim of improving thermal stability of EVA copolymer, adhesives based on EVA/PMMA polymer blends were used, where Elvax 410 was chosen as EVA copolymer with better thermal stability. Compatibilization of EVA/PMMA polymer blends was performed using in situ free radical polymerization, where raw EVA-g- PMMA adhesive was synthesized. Controlled „living” polymerization was employed in the aim of controlling the adhesion and compatibilization by graft chain length. Characterization of polymer blends consists of chemical structure examination, determining of adhesive and thermal properties in relation to EVA copolymers and physical polymer blend EVA/PMMA. The adhesion test of optical fibers with adhesives showed that the improved adhesion was achieved by modification of physical polymer blend. The type of adhesive failure was determined by optical microscopy that showed the difference between used polymeric adhesives. Compatibilization effect was monitored on optical microscope by phase separation in polymer blends and by determining of wetting angles. Adhesive properties after accelerated aging on 60 °C after 60 and 120 hours were examined. Thermogravimetry coupled with mass spectroscopy indicated that the adhesive raw EVA-g-PMMA had improved thermal stability..

O hitnosti usvajanja izmjena regulatornog okvira osiguranja – prijedlog izmjena Zakona o obveznim odnosima Republike Hrvatske

Autorica nastoji odgovoriti na pitanje zahtijeva li ugovor o osiguranju hitne izmjene regulatornog okvira. Oslanjajući se na rezultat usporednopravne analize, autorica se zalaže za usvajanje izmjena Zakona o obveznim odnosima (dalje: ZOO) kao jednog od najbitnijih propisa u procesu harmonizacije hrvatskog prava sa pravom Europske unije. Izmjene ZOO opravdava nekoliko argumenata, od kojih autorica izdvaja masovnost ugovora o osiguranju, osobitosti po kojima se ovaj ugovor izdvaja od ostatka ugovornog prava, potrebu za usvajanjem poticajnog regulatornog okvira za potrošače usluga osiguranja i dinamičnost materije. Ovakvo opredjeljenje ne isključuje uređenje ugovora o osiguranju posebnim propisom koji bi predstavljao logičan nastanak započetih reformi. Autorica se zalaže upravo za to, ali preporučuje da se zakonodavna tehnika i količina/obujam materije prilagode dvadeset i prvom stoljeću i prirodi ovog značajnog ugovora. Naime, izmjenama ZOO treba ostvariti dva cilja: postaviti temelj novog regulatornog okvira osiguranja u hrvatskom pravu i ojačati bedeme pravne zaštite slabije ugovorne strane. Sve to treba činiti imperativnim i poluimperativnim normama, dok sva pitanja koja bi mogla biti uređena dispozitivnim normama treba ostaviti predmetu posebnog ugovornog zakona osiguranja. Norme ZOO Hrvatske trebale bi biti opće i sustavne te kao takve nužan, ali ne i dovoljan regulator pravnog odnosa osiguranja u dvadeset i prvom stoljeću. One će biti dopunjene, razrađene i konkretizirane Zakonom o ugovoru o osiguranju, donesenim po ugledu na reprezentativna zakonodavstva osiguranja, od kojih autorica izdvaja njemačko i francusko pravo

Schlichtung im Versicherungsbereich

S obzirom na sve prednosti medijacije, kao forme alternativnog rešavanja sporova, ona predstavlja najbrži i najjeftiniji način njihovog rešavanja. Poziciju u ponudi usluga pravne zaštite jedne države, medijacija može graditi na temelju dokazane neefikasnosti i preterane sporosti državnih sudova. Kao protivteža državnom sistemu pružanja zaštite, strogo formalnom i vrlo skupom, medijacija pruža stranama osećaj da je rešenje spora u njihovim rukama. Ova razlika u odnosu na druge načine rešavanja sporova izdvaja medijaciju i deluje podsticajno na njeno prihvatanje. Članak se bavi utvrđivanjem razloga koji opravdavaju uvođenje medijacije u osiguranju. Nakon navođenja argumenata u prilog medijacije uopšte, autor izdvaja uštedu troškova parničenja, izbegavanje negativnog imidža osiguravača, interesnu orjentaciju i nepostojanje ovlašćenja medijatora da donese obavezujuću odluku kao faktore koji bi mogli uticati na prihvatanje ovog metoda ADR u oblasti osiguranja. U drugom delu rada se postavlja pitanje medijabilnosti sporova iz osiguranja. Polazeći od osnovnih obeležja savremene regulative osiguranja, a pre svih potrebe zaštite osiguranika i korisnika usluga osiguranja, autor dolazi do zaključka da implementiranje prakse rešavanja sporova medijacijom, a ne sudskim putem, nije u suprotnosti sa najnovijim tendencijama u ovoj oblasti. Autor se zalaže za stvaranje pravne infrastrukture i društvene klime pogodne za promenu parničnog mentaliteta i usvajanje pristupa po kome je medijacija u oblasti osiguranja prethodan i redovan tok stvari, koji će, u velikom broju slučajeva, rezultirati prevencijom ovih sporova. Najzad, poslednji deo rada kritički razmatra rešenja srpskog prava, a najviše pažnje posvećuje pitanju da li je Narodna banka Srbije najpogodnija institucija za vršenje funkcije posredovanja u osiguranju. Autor zaključuje da je opredeljenje za uvođenje medijacije u osiguranju u interesu i osiguravača i korisnika njegovih usluga, jer pored neposrednih koristi (poput uštede u vremenu i novcu), donosi i posredne koristi (poput očuvanja dugoročnih poslovnih odnosa i unapređenja poslovanja).As a form of alternative disputes resolution the mediation has numerous benefits, e.g. it presents the quickest and most convenient way to settle disputes. Its position of offering legal services in a country the mediation can build on a basis of already proved inefficient and excessively slow judiciary. It is a counterpoise to strictly formal and overexpensive state system for providing legal protection, and therefore, in mediation parties feel that the resolution of their dispute is in their hands. This characteristic singles out the mediation from other methods of dispute resolution and has a positive effect on its acceptance. The article deals with reasons to justify implementation of insurance mediation. In the first part of the article, the author explains arguments in favour of mediation in general. Furthermore, she stresses litigation cost savings, negative image avoidance of the insurer, interest orientation of the mediator and lack of powers to deliver a binding decision as factors which could have an effect on this ADR model’s acceptance in the field of insurance. In the second part of the article the author pays a special attention to the issue of mediability of disputes over insurance. Having in mind basic characteristics of modern insurance regulations, in particular the need to protect a policy holder and insurance customer, the author draws a conclusion that implementation of practice to resolve disputes by mediation, but not in front of the court, has not been contrary to the most recent tendencies in this legal field. The author calls for creation of legal infrastructure and social climate which could change people thinking about litigation and accept mediation of insurance disputes as a prior and regular course of dispute resolution, which could, in numerous cases, prevent future disputes. The last part of the article presents critical assessments of Serbian law paying special attention to the question whether the Serbian National Bank is best institution to take a function of mediator in insurance disputes. The author firmly believes that mediation of insurance disputes is in the interest of insurer and policy holders benefiting them directly (reducing costs and time) and indirectly (maintaining long-lasting business relationships and improving business performance).Schlichtung, als eine Form alternativer Beilegung von Rechtsstreitigkeiten, stellt die schnellste und die günstigste Form der Beilegung von Rechtsstreitigkeiten dar. Zu Gunsten der Schlichtung, als einer Methode für den Rechtsschutz eines Staates, spricht die bewiesene Ineffizienz und Langsamkeit der staatlichen Gerichte. Im Gegensatz zu dem staatlichen Schutzsystem, das sowohl streng formell als auch sehr teuer sei, haben die Parteien bei einem Schlichtungsverfahren das Gefühl, die Beilegung der Streitigkeit liege in ihren Händen. Dadurch unterscheidet sich Schlichtung von anderen Formen der Rechtstreitigkeitenbeilegung was zur Förderung und zur Annahme dieser Art von Konfliktregelung beiträgt. Die vorliegende Arbeit beschäftigt sich mit der Feststellung von Gründen, die Einführung von Schlichtung in das Versicherungsbereich rechtfertigen. Außer allgemeiner Argumente zu Gunsten der Schlichtung, betont die Autorin als besonders wichtig Ersparen von Prozesskosten, Meidung des negativen Images der Versicherer, Interessenorientierung, und das Nichtvorhandensein der Ermächtigung von Schlichtern, eine verbindliche Entscheidung zu treffen, was die Annahme dieser Methode alternativer Beilegung von Rechtsstreitigkeiten im Versicherungsbereich beeinflussen könnte. Im zweiten Teil dieser Arbeit stellt sich die Frage, welche Streitigkeiten aus dem Versicherungsbereich für Schlichtung geeignet seien. Weiterhin betrachtet die Autorin die Grundmerkmale gegenwärtiger Versicherungsregulative, vor allem den Bedarf an Schutz vor den Versicherern und den Benutzern von Versicherungsdienste. Daraus schließt sie, dass die Einführung von Schlichtung an Stelle Gerichtsverfahren für Streitigkeitenbeilegung, nicht den neusten Trends in diesem Bereich entgegengesetzt ist. Daher setzt sich die Autorin für die Schaffung einer Rechtsinfrastruktur und gesellschaftlicher Klima ein, welche nicht nur für die Änderung der Gerichtsverfahrenorientierten Mentalität erforderlich ist, sondern zur Annahme von Schlichtung als üblicher Vorgehensweise im Versicherungsbereich beitragen könnte, was wiederum zur Verhinderung diesbezüglicher Streitigkeiten führen würde. Zum Schluss werden die Lösungen des serbischen Rechts kritisch unter die Lupe genommen, und es wird betrachtet, ob die Nationalbank Serbiens die meist geeignete Institution sei, als Vermittler in Versicherungsbereich zu fungieren. Letztendlich stellt die Autorin fest, dass die Einführung von Schlichtung in das Versicherungsbereich im Interesse sowohl der Versicherer als auch der Benutzer ihrer Dienste liegt, weil dies neben direkten Vorteilen (wie Zeit- und Geldersparung), auch indirekte Vorteile (wie z.B. Bewahrung von langzeitigen Geschäftsverhältnissen und Förderung von Geschäftsabwicklung) bewirkt

Adsorption and photocatalytic properties of nanomaterials based on cerium(IV) oxide and titanium(IV) oxide

Циљ овог истраживања је синтеза различитих облика наноструктурних прахова, базираних на оксидима церијума и титанијума, као и анализа њихових структурних, електронских, морфолошких и текстуралних особина како би се испитао њихов утицај на могућу примену ових нанопрахова као адсорбената и/или фотокатализатора за различите органске боје. Први део тезе укључује испитивање различито синтетисаних нанопрахова CeO2, док се други део тезе односи на проучавање нанопрахова базираних на TiO2, са акцентом на недовољно испитану брукитну фазу. Карактеризација добијених материјала и њихове адсорпционе/фотокаталитичке особине испитане су дифракцијом рендгенског зрачења на праху, раманском спектроскопијом, инфрацрвеном спектроскопијом са фуријеовом трансформацијом, скенирајућом електронском микроскопијом, методом физисорпције азота, елипсометријом, термогравиметријском методом и УЉ/ВИС спектроскопијом.Нанопрахови CeO2 синтетисани су коришћењем три начина синтезе: самопропагирајућом синтезом на собној температури (CeO2-δ-S), хидротермалном методом (CeO2-δ-H) и методом преципитације (CeO2-δ-P). Испитиван је утицај синтезе на адсорпциона и фотокаталитичка својства коришћењем три различите азо боје: Reactive Orange 16 (RO16), Methyl Orange (MO) и Mordant Blue 9 (MB9). Нанопрах CeO2−δ-S, синтетисан брзом и ефикасном самопропагирајућом методом, пронађен је као врло ефикасан адсорбент за боје и може бити обећавајући материјал у третману отпадних вода. Овај нанопрах је показао сличне адсорпционе особине када је у питању МО боја, у поређењу са комерцијалним активним угљеником, док CeO2−δ-S показује још бољу адсорпциону способност од активног угљеника за RO16 боју. На основу адсорпционих изотерми за узорак CeO2−δ-S, показано је да Лангмиров модел мало боље описује изотерме за МО и RO16, док се Фројндлиховим моделом боље фитују подаци када је у питању изотерма за MB9 у целом опсегу концентрација. Одређене су и вредности максималних адсорпционих капацитета нанопраха CeO2−δ-S за све три боје. Утврђен је и предложен механизам адсорпционог процеса нанопраха CeO2−δ-S,који је базиран на информацијама добијеним из инфрацрвених спектара и експериментално одређене вредности тачке нултог наелектрисања (pHZPC). Формирање бидентатног моста између сулфонских група и Ce4+ катјона, као и протонизација површинских хидроксилних група церијум-диоксида сматрају се одговорним за ефикасност адсорпционог процеса. Показано је такође да адсорпциони процес церијум-диоксида прати кинетички модел псеудо-другог реда, што подразумева да поред јаке електростатичке интеракције, хемисорпција игра кључну улогу у адсорпцији боја. С друге стране, нанопрахови CeO2-δ-H и CeO2-δ-P су показали одсуство адсорпције за азо боје. Међутим, њихова фотокаталитичка активност испитана је кроз деградацију азо боје RO16, при чему је разлика у њиховој активности корелисана са разликом у електронској структури и димензијама кристалита...The aim of this thesis is to synthesize the various forms of nanostructured powders, based on cerium- and titanium- oxides, and to analyze as well their structural, electronic, morphological, and textural properties in order to examine their influence on potential application of these materials as adsorbents and/or photocatalysts for different organic dyes. The first part of the thesis includes examination of different synthesized nanocrystalline powders of CeO2, while the second part deals with the study of the nanopowders based on TiO2, with emphasize on the insufficiently known and examined brookite phase. Characterization of synthesized powders and their adsorption/photocatalytic properties is done by X-ray diffraction method, Raman spectroscopy, Fourier transform infrared Spectroscopy, Scanning electronic microscopy, N2 physisorption measurements, Ellipsometry, Thermogravimetric analysis and UV/VIS spectroscopy.CeO2 nanopowders are synthesized using three different methods such as self-propagating room temperature (CeO2-δ-S), hydrothermal (CeO2-δ-H) and precipitation method (CeO2-δ-P). The effect of preparation procedure on the adsorption and photocatalytic properties is investigated by using three synthetic azo dyes such as Reactive Orange 16 (RO16), Methyl Orange (MO), and Mordant Blue 9 (MB9). The CeO2−δ-S nanopowder, synthesized by a facile and cost effective SPRT method, is found to be an effective dye adsorbent and can be a promising substitute in wastewater treatment. In comparison to commercial powdered activated carbon (AC), adsorption properties of CeO2−δ-S for MO dye are found to be similar, whereas the CeO2−δ-S demonstrates even better adsorption capability than AC for RO16 dye. By studying the equilibrium adsorption data for CeO2−δ-S, it is shown that the Langmuir model slightly better describes isotherm data for MO and RO16, while the Freundlich model is a better fit for MB9 over the whole concentration range. The maximum adsorption capacities of CeO2−δ-S for all three dyes were measured. The mechanism of CeO2−δ adsorption process, mostly based on the information derived from the Infrared spectra andexperimentally determined value for Zero Point Charge (pHZPC), is established and proposed. The formation of a bidentate type bridge between sulfonate group and Ce4+ cations and the protonation of ceria surface hydroxyls is found to be responsible for effective adsorption process. It is also shown that the adsorption process follows the pseudo-second-order kinetic model, indicating that besides the strong electrostatic interaction, chemisorption plays an important role for the dye adsorption. On the other hand, the absence of adsorption of both CeO2-δ-H and CeO2-δ-P powders is found. However, their photocatalytic activity toward RO16 azo dye is examined, while the difference in their activity is correlated to difference in their electronic structure and crystallite size..

CONCENTRATION RISK FOR PLACED ASSETS BY THE LARGEST BANKS IN SERBIA

The fact that the U.S., in the recent past, faced a financial collapse which led to the global economic crisis, and the fact that the euro zone felt the financial collapse of Greece about five years ago has caused the public sector in Serbia, as well as all European countries to be seriously shaken. The significant decrease of transactions in the money market has resulted in the increase of exchange rates, the decline in interest rates, inflation and a decrease in the GDP. This has all been reflected on the economy, which has drastically reduced the number of employees, which has had a direct impact on the living standards of the population With the decrease in living standards, people are in a weaker position to pay back loans, which in turn can lead to some global crisis. The vicious circle is hard to break, and the European and world public is directing its forces, on one hand, to the recovery of the economy and on the other to bailing out banks. In this situation, it is not easy for banks to decide how to optimize the risk they are exposed to, i.e., which industrial branch, for what term and which region is the most optimal for investments. The authors have conducted a study, the results of which illustrate the current situation in Serbia and the trends in Serbia's largest banks

The Hybridization of the Regulatory Framework of Insurance Contract Law: Elements of a New Setting

This article aims to highlight the phenomenon of hybridization of insurance contract law, which started with its emancipation from contract law. The next phase included its internal stratification, stemming from obvious differences between commercial and consumer insurance, and various contractual positions of contracting parties in these different insurance contracts. Two features of insurance contracts regulation are addressed, based on Serbian law as it currently stands, as well as comparative legal analysis. The first feature is that the legislatively envisaged unified regime for insurance contracts is incomplete and inadequate for all manifestations of this contract. The second feature is that regulation of this matter must enable balancing of interests between insurers and insureds, especially consumers. The authors conclude that insurance regulation can only be conducive when simultaneously ensuring protection of the weaker party, protecting insurers from the negligent actions of the insured, while facilitating conduct of insurance business

Penicillin allergy evaluation: Experience from Clinic of Allergology and Immunology, Clinical Center of Serbia

Introduction: Beta(β)-lactam antibiotics are one of the most prescribed medical drugs worldwide. The incidence of self-reported penicillin allergy ranges from 1 to 10 percent. Patients with registered allergy on β-lactam antibiotics are treated with drugs of second choice which are usually more toxic and more expensive. Aim: The aim of this study was to exam the prevalence of penicillin allergy and correlation of clinical, laboratory and socio-demographic characteristic of patients with and without hypersensitivity to penicillin which were available in medical records. Material and methods: This retrospective, descriptive study included consecutive patients, which were treated in Clinic of Allergology and Immunology, Clinical Center of Serbia (CCS), in the period between the years 2010-2015. Anamnestic data of patients with self-reported allergic reaction to penicilin and the rest of β-lactam antibiotics were used, as well as results of in vivo and in vitro tests. Results: 81 patients were evaluated in the study, of which 59 (72.8%) were females. The average age of patients was 41.7±16.47 years. Adverse effects to penicillin were reported by 70/81 (86.4%) tested patients. In accordance with other studies, the most common initial symptoms were rash (exanthema) and angioedema. None of the 70 patients with self-reported allergic reaction to penicillin had positive in vitro tests. Total number of patients with positive in vivo tests is 2/81 (2.5%) Conclusion: Despite a small percentage of positive penicillin hypersensitivity tests of patients with anamnestic data of self-reported allergic reaction, it is necessary to perform in vivo drug provocation test as a gold standard for confirmation of penicillin hypesensitivity in order to reduce the utilization of alternative antimicrobial drugs, the risk of microbial resistance and treatment costs

Protective effects of olive oil phenolics oleuropein and hydroxytyrosol against hydrogen peroxide-induced DNA damage in human peripheral lymphocytes

This study investigates antioxidant capacity and protective effects of phenolic compounds oleuropein (OLP) and hydroxytyrosol (HT), present in olive oil and olive leaves, against H2O2-induced DNA damage in human peripheral lymphocytes. Antioxidant potency was determined using the measurement of radical-scavenging activity (ABTS∙+ assay), ferric reducing power (FRAP assay) and cupric reducing antioxidant capacity (CUPRAC assay). Both substances were found to be potent antioxidant agents due to their free radical-scavenging activities. Antigenotoxic effects of oleuropein and hydroxytyrosol against H2O2-induced damage in human lymphocytes were evaluated in vitro by alkaline comet assay. At tested concentrations (1, 5, 10 µmol L–1), oleuropein and hydroxytyrosol did not induce a significant increase of primary DNA damage in comparison with the negative control. Pretreatment of human lymphocytes with each of the substances for 120 min produced a dose-dependent reduction of primary DNA damage in the tested cell type. Hydroxytyrosol showed a better protective effect against H2O2-induced DNA breaks than oleuropein which could be associated with their free radical-scavenging efficacy