Utjecaj specifične veze između materijala i prevlake na tribološke i zaštitne karakteristike proizvoda

Today, parts and tools are increasingly made of composite materials. Realization of specific connection between basic material and coating is very important. The quality of coating on products, in terms of wear and resistance to destruction, has a large impact on productivity and reliability of production processes, in particular their life. In this paper, based on experimental investigations, the effect of specific relationship between the base material and coating on tribological and protective features of the product is analyzed.Danas se dijelovi i alati sve češće izrađuju iz kombiniranih materijala. Ostvarenje specifične veze između osnovnog materijala i prevlake je izuzetno značajno. Kvaliteta prevlake na proizvodima, sa aspekta habanja i otpornosti na razaranje, ima velik utjecaj na produktivnost i pouzdanost proizvodnih procesa, a osobito na njihov vijek trajanja. U radu je na temelju eksperimentalnih istraživanja analiziran utjecaj specifične veze između osnovnog materijala i prevlake na tribološke i zaštitne karakteristike proizvoda

Metodologija mjerenja karakteristika i izbor materijala elemenata tribomehaničkih sustava

Achieving the equality between the time of functional aging of mechanical systems and the time of allowed wear of the system elements is the main task of tribology. This can be reached by choosing the optimal material of elements of tribo-mehanical systems. The paper gives the results of experimental research of tribological and mechanical characteristics several pairs of material. Investigations were performed on the device with a rotating disc and static pin.Dostizanje jednakosti vjeka funkcionalnog starenja strojnih sustava i vjeka dopuštenog habanja elemenata sustava, je osnovni zadatak tribologije, koji je moguće izvesti izborom optimalnog materijala elemenata tribomehaničkog sustava. U radu se daju rezultati eksperimentalnih istraživanja triboloških i mehaničkih karakteristika više parova materijala. Istraživanja su izvedena na uređaju sa rotirajućim diskom i mirujućim pinom

Rheologycal properties of sodium carboxymethylcellulose in the presence of electrolyte and mixed micelle of surfactants

One of the most significant aspects of polymer-surfactant interaction, from the practical point of view, is that of rheology control and viscosity enhancement. In the oppositely charged polyelectrolyte-surfactant system strong ionic interaction often leads to precipitation of the formed complex yielding serious problems. In this paper the interaction between anionic polyelectrolyte - sodium carboxymethylcellulose (NaCMC) and cationic surfactant - cethyltrimethylammonium bromide (CTMAB) has been investigated by rheological measurements. Addition of electrolyte NaBr and nonionic surfactant - Tween 80 reduced the binding strength, prevented the precipitation of the complex and increased the viscosity of the system. It was found that rheological properties are strong influenced by NaCMC-CTMAB interaction and the system exhibits either pseudoplastic or thixotropic or rheopectic behavior according to the intensity of interaction

Supplementary data for article: Petković, B. B.; Stanković, D.; Milčić, M.; Sovilj, S. P.; Manojlović, D. Dinuclear Copper(II) Octaazamacrocyclic Complex in a PVC Coated GCE and Graphite as a Voltammetric Sensor for Determination of Gallic Acid and Antioxidant Capacity of Wine Samples. Talanta 2015, 132, 513–519. https://doi.org/10.1016/j.talanta.2014.09.025

Supplementary material for: [https://doi.org/10.1016/j.talanta.2014.09.025]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1654]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3363

Rheological properties of hydroxypropylmethyl cellulose/sodium dodecylsulfate mixtures

Rheological properties of mixtures of hydroxypropylmethyl cellulose (HPMC), a nonionic associative cellulose ether, and sodium dodecylsulfate (SDS), an anionic surfactant, were investigated by viscosity measurements performed at different shear rates (0.1-6000 s-1). HPMC/SDS mixtures containing different concentrations of SDS (CSDS=0.00-3.50 % w/w) and HPMC concentrations which corresponded to the overlap parameter c/c*=3, 6, and 12 were prepared. All HPMC/SDS mixtures were found to be shear-thinning when examined in a low-end-to mid-range of the applied shear rates. The degree of shear-thinning, n, and viscosity of the mixtures were influenced by composition of HPMC/SDS mixtures and HPMC-SDS complex formation. The changes in n ranged from values typical for highly shear thinning to almost perfectly Newtonian liquids, and were more pronounced as c/c* was increased from 3 to 6 and 12. A change in flow profile and a buildup of the first normal stress difference (N1) was observed in HPMC/SDS mixtures with c/c*=6 and 12 and CSDS 0.55-1.00 % and 0.55-2.50 %, respectively, when a critical shear rate, crit. was exceeded, suggesting that a shear-induced structure formation in the mixtures took place. [Projekat Ministartsva nauke Republike Srbije, br. Grant III 46010

Supplementary data for article: Petković, B. B.; Stanković, D.; Milčić, M.; Sovilj, S. P.; Manojlović, D. Dinuclear Copper(II) Octaazamacrocyclic Complex in a PVC Coated GCE and Graphite as a Voltammetric Sensor for Determination of Gallic Acid and Antioxidant Capacity of Wine Samples. Talanta 2015, 132, 513–519. https://doi.org/10.1016/j.talanta.2014.09.025

Supplementary material for: [https://doi.org/10.1016/j.talanta.2014.09.025]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1654]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3363

3D finite element electrical model of larval zebrafish ECG signals

Assessment of heart function in zebrafish larvae using electrocardiography (ECG) is a potentially useful tool in developing cardiac treatments and the assessment of drug therapies. In order to better understand how a measured ECG waveform is related to the structure of the heart, its position within the larva and the position of the electrodes, a 3D model of a 3 days post fertilisation (dpf) larval zebrafish was developed to simulate cardiac electrical activity and investigate the voltage distribution throughout the body. The geometry consisted of two main components; the zebrafish body was modelled as a homogeneous volume, while the heart was split into five distinct regions (sinoatrial region, atrial wall, atrioventricular band, ventricular wall and heart chambers). Similarly, the electrical model consisted of two parts with the body described by Laplace’s equation and the heart using a bidomain ionic model based upon the Fitzhugh-Nagumo equations. Each region of the heart was differentiated by action potential (AP) parameters and activation wave conduction velocities, which were fitted and scaled based on previously published experimental results. ECG measurements in vivo at different electrode recording positions were then compared to the model results. The model was able to simulate action potentials, wave propagation and all the major features (P wave, R wave, T wave) of the ECG, as well as polarity of the peaks observed at each position. This model was based upon our current understanding of the structure of the normal zebrafish larval heart. Further development would enable us to incorporate features associated with the diseased heart and hence assist in the interpretation of larval zebrafish ECGs in these conditions

The effect of specifi c relationship between material and coating on tribological and protective features of the product

Today, parts and tools are increasingly made of composite materials. Realization of specifi c connection between basic material and coating is very important. The quality of coating on products, in terms of wear and resistance to destruction, has a large impact on productivity and reliability of production processes, in particular their life. In this paper, based on experimental investigations, the effect of specific relationship between the base material and coating on tribological and protective features of the product is analyzed