Electrochemical and Spectroscopic Study of Benzotriazole Films Formed on Copper, Copper-zinc Alloys and Zinc in Chloride Solution

The formation of protective layers on copper, zinc and copper-zinc (Cu-10Zn and Cu-40Zn) alloys at open circuit potential in aerated, near neutral 0.5 M NaCl solution containing benzotriazole (BTA) was studied using potentiodynamic measurements, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The addition of benzotriazole affects the dissolution of the materials investigated. Benzotriazole, generally known as an inhibitor of copper corrosion, is also shown to be an efficient inhibitor for copper-zinc alloys and zinc metal. The effectiveness of inhibition depending on the type of materials was compared. X-ray photoelectron spectroscopic results showed that the surface layer formed on alloys in BTA-inhibited solution comprised both oxide and polymer components. The formation of Cu2O/Cu(I)-BTA on copper, mixed oxides/Zn(II)-BTA and Cu(I)-BTA on copper-zinc alloys and ZnO/Zn(II)-BTA polymer surface film on zinc provides an effective barrier against corrosion on materials investigated in chloride solution

Nanocoatings for preventing orthopaedic implant–associated bacterial infections

The Research department of the Valdoltra Orthopaedic Hospital is determined to conduct more extensive research studies on modification of materials for orthopaedic implants. The starting research in the newly founded Research laboratory shall include basic and applied studies which results shall be potentially considered and eventually implemented in daily clinical practice of Valdoltra Orthopaedic Hospital. With an accurate inspection of the emerging medical needs in the field of orthopaedics we envisaged the urgent need to provide a long-term protection for orthopaedic prostheses. By means of using nano-engineering approaches for the functionalization of orthopaedic implant surfaces with suitable antimicrobial agents, it is possible to protect orthopaedic implants against harmful bacteria, which trigger the initiation of implantassociated bacterial infection. As the implant-associated bacterial infection can affect the longevity of the prosthesis, thus, the scientific and financial efforts, with the help of the project Trans2care, will be focused substantially on the design and fabrication of protective antibacterial coatings for orthopaedic implants

Inhibitory effects of chitosan coating against biofilm formation on metal implants

An effective approach to combat bacteria adhesion onto metallic implants surface is to functionalize the biomaterial surface such that bacterial growth could be impaired or the bacteria are killed upon contact with the surfaces. In the recent years, a majority of the research in material science has been devoted to modification or functionalization of implant surfaces with composite coatings with bactericidal capability such as polymeric coatings. For instance, chitosan (CH) is a polycationic polysaccharide which antibacterial properties and osteoblast function-enhancing nature has received substantial interest. The main goal of our study was to evaluate the effect of different chitosan-coated metals, routinely used in orthopaedics, on the survival of Staphylococcus epidermidis and Staphylococcus aureus. The results clearly showed that survival of attached bacteria onto metals functionalized with chitosan was lower when compared to bacterial survival determined on the surface of unmodified metals. Moreover, chitosan coating caused bacterial cells to lose their regular spherical shape. Thus, the results proved that chitosan could be used as alternative material for the preparation of antimicrobial coatings for implants

Effect of anodization on the surface characteristics and electrochemical behaviour of zirconium in artificial saliva

The paper is focused on elaboration of ZrO2 films on pure zirconium via anodizing inphosphoric acid with and without fluoride at constant potentials of 30 V and 60 V. Thestructure and composition of the films were investigated using scanning electronicmicroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The composition ofthe oxides formed at both potentials can be identified as monoclinic ZrO2. In addition to Zrand O, the layers formed in phosphoric acid contain phosphorus originating from thephosphoric acid. When the phosphoric acid solution contains NaF, fluorine is alsoincorporated into the oxide layer. The oxides formed at a higher voltage have greaterroughness than those formed at 30 V. Anodized samples exhibit smaller current densitiesduring anodic polarization compared to the as-received zirconium covered with native oxide.Fil: Romonti, Daniela E.. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Gomez Sanchez, Andrea Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Milošev, Ingrid. Jožef Stefan Institute; EsloveniaFil: Demetrescu, Ioana. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Extreme value theory in emerging markets

This paper investigates the performance of extreme value theory (EVT) with the daily stock index returns of four different emerging markets. The research covers the sample representing the Serbian (BELEXline), Croatian (CROBEX), Slovenian (SBI20), and Hungarian (BUX) stock indexes using the data from January 2006 - September 2009. In the paper a performance test was carried out for the success of application of the extreme value theory in estimating and forecasting of the tails of daily return distribution of the analyzed stock indexes. Therefore the main goal is to determine whether EVT adequately estimates and forecasts the tails (2.5% and 5% at the tail) of daily stock index return distribution in the emerging markets of Serbia, Croatia, Slovenia, and Hungary. The applied methodology during the research includes analysis, synthesis and statistical/mathematical methods. Research results according to estimated Generalized Pareto Distribution (GPD) parameters indicate the necessity of applying market risk estimation methods, i.e. extreme value theory (EVT) in the framework of a broader analysis of investment processes in emerging markets

Laringealni hondrosarkom: uspješna primjena videolaringoskopa u zbrinjavanju očekivanog otežanog dišnog puta

Laryngeal chondrosarcoma is a rare mesenchymal tumor, most frequently affecting cricoid cartilage. The objective of this report is to present successful video laryngoscope usage in a patient with anticipated difficult airway who refused awake fiberoptic endotracheal intubation (AFOI). A 59-year-old male patient was admitted in our hospital due to difficulty breathing and swallowing. On clinical examination performed by ENT surgeon, preoperative endoscopic airway examination (PEAE) could not be performed properly due to the patient’s uncooperativeness. Computed tomography revealed a spherical tumor that obstructed the subglottic area almost entirely. Due to the narrowed airway, the first choice for the anticipated difficult airway management was AFOI, which the patient refused. Consequently, we decided to perform endotracheal intubation with indirect laryngoscope using a C-MAC video laryngoscope (Karl Storz, Tuttlingen, Germany). Reinforced endotracheal tube (6.0 mm internal diameter) was placed gently between the tumor mass and the posterior wall of the trachea in the first attempt. Confirmation of endotracheal intubation was done by capnography. In a patient with subglottic area chondrosarcoma refusing PEAE and AFOI, video laryngoscope is a particularly helpful device for difficult airway management when difficult airway is anticipated.Laringealni hondrosarkom je rijedak mezenhimni tumor koji najčešće zahvaća krikoidnu hrskavicu. Svrha ovoga rada je prikazati uspješnu primjenu videolaringoskopa u bolesnika s očekivanim otežanim dišnim putem koji odbija fiberoptičku endotrahealnu intubaciju na budno. Pedesetdevetogodišnji muškarac je primljen u našu bolnicu zbog otežanog disanja i gutanja. Zbog nesuradljivosti bolesnika otorinolaringolog nije uspio učiniti odgovarajući prijeoperacijski endoskopski pregled dišnog puta. Učinjena kompjutorska tomografija je pokazala sferičan tumor koji je skoro u potpunosti opstruirao subglotično područje. Zbog uskog dišnog puta prvi izbor za postupak s očekivanim otežanim dišnim putom je bila fiberoptička endotrahealna intubacija na budno koju je bolesnik odbio. Posljedično, odlučili smo izvesti endotrahealnu intubaciju indirektnom laringoskopijom pomoću videolaringoskopa C-MAC (Karl Storz, Tuttlingen, Njemačka). U prvom pokušaju je armirani endotrahealni tubus (unutarnji promjer 6,0 mm) nježno postavljen između tumorske mase i stražnjega zida traheje. Kapnografom je potvrđena endotrahealna intubacija. Zaključno, videolaringoskop je korisno pomagalo u održavanju otežanog dišnog puta u bolesnika s hondrosarkomom subglotičnog područja koji odbija fiberoptičku endotrahealnu intubaciju na budno, a u kojega se očekuje otežani dišni put

DETERMINATIONS OF PROFITABILITY IN THE AGRICULUTRAL SECTOR IN SERBIA

This research paper considers performance determinants at firm and industry level from the perspective of agricultural industry since this industry is recognized as one of key drivers of Serbian national economy. Sample is consisted of 115 large and medium-sized firms as they participate around 50% in total sector turnover, during years 2017 - 2021. The Generalized Method of Moments was used to analyze how firm factors (lagged profitability, leverage, labor cost, size, liquidity, sales growth) and industry factors (market share and capital intensity) affect profitability. Research results showed that profitability is strongly positively affected by its past values and stronlgy negatively affected by leverage, labours costs and industry factor capital intensity. The results suggest that internal factors are key determinants of the performance of agricultural firms rather than external factors and that leverage is the most significant determinant of profitability therefore managers should pay more attention to debt policy