Characterization of carbon fibrous material from platanus achenes as platinum catalysts support

Carbon materials with developed porosity are usually used as supports for platinum catalysts. Physico-chemical characteristics of the support influence the properties of platinum deposited and its catalytic activity. In our studies, we deposited platinum on carbon fibrous like materials obtained from platanus seeds - achenes. The precursor was chemically activated with different reagents: NaOH, pyrogallol, and H2O2, before the carbonization process. Platinum was deposited on all substrates to study the influence of the substrate properties on the activity of the catalyst. Carbon materials were characterized by nitrogen adsorption/desorption isotherms measurements, X-ray diffraction, and scanning electron microscopy. It was noticed that the adsorption characteristics of carbon support affected the structure of platinum deposits and thus their activity

The Effect of Phases of the Adoption of the Circular Economy on Firm Performance: Evidence from 28 EU Countries

Although a substantial body of literature has analysed the potential benefits of the circular economy, empirical evidence on the relationship between circular economy-related activities and firm performance is scarce. Rather than analysing only the effect of the circular economy on firm performance, we empirically examine the effects of the different phases of the adoption process of the circular economy on firm performance. Therefore, in this paper, a multiphase framework of circular economy adoption is developed. Employing a propensity-score-matching model on the sample of more than 4000 European SMEs, we show that the adoption of circular economy activities improves firm performance as measured by productivity. In addition, our findings reveal that the impact of circular economy activities on firm performance is dependent on the different phases of the adoption process. Taken together, this study enriches current research on the circular economy by contributing to a more nuanced understanding on the relationship between the different phases of the adoption process and firm performance

The galvanostatic reduction on modified platinum electrode and determination of trinitrotoluene in neutral solution

The study of the electrochemical reduction on acetonitrile modified platinum electrode and determination of trinitrotoluene (TNT) in neutral solution by simple galvanostatic technique is presented here. The obtained potential-time responses on the applied constant cathodic current pulses showed two potential transitions before achieving the steady-states, referring to the multi-step reduction process of nitro groups in TNT molecule. The calibration curves of the dependence of the square root of the first transition time (τ 0.5) on the TNT concentration were linear in the ranges 4.4 – 303.8 μM and 0.09 – 4.40 μM for applied constant current of 0.1 mA. The detection limit was 0.09 μM. The method was tested in the river water. The results indicated the sensitivity of the galvanostatic method for TNT determination in the environmental samples. From the first transition on the E-t curves the characteristics important for the understanding the mechanism of the reduction process were obtained. It was found that four electrons are involved in the reduction process of the first nitro group, indicating that the reduction product in a neutral electrolyte is hydroxylamine.\ud Keywords

A framework for Comminution Circuits Design evaluation using grey compromise programming

Comminution process, particularly grinding, is very important in the mineral processing industry. Some characteristics of ore particles, which occur as a product of grinding process, have a significant impact on the effects of further ore processing. At the same time, this process requires a significant amount of energy and also significantly affects the overall processing costs. Therefore, in this paper, we propose new multiple criteria decision making model based on grey compromise programming for adequate comminution circuit design selection. Although it is based on a simple procedure, we consider that the proposed model is efficient and flexible, and that it also represents the basis for forming more sophisticated models for comminution circuit design selection, as in addition, many other decision making problems in business environment, which is characterized by predictions and uncertainty

Convergence on EU and USA Food Safety Regulation Approach, Regarding Foodborne Outbreaks

AbstractInternational food trade facilitates transport of either fresh food or traditional products worldwide. This facilitates availability of foodstuff, and enables migration of unsafe food. The most common food safety risk are foodborne pathogens, since they are ubiquitous and can cause epidemic spread. European Union and USA markets are the most dynamic in the world, so it was necessary to obtain satisfactory regulations at national and international level. Official number of foodborne outbreaks in 2013 are 5196 for Europe and 818 for the US. FSMA is the latest US policy change in approaching to Europe practice of preventing rather than reparing

Photoelectrochemical properties of sol–gel obtained titanium oxide

The photoelectrochemical properties of a sol–gel prepared titanium oxide coating applied onto a Ti substrate were investigated. The oxide coating was formed from an inorganic sol thermally treated in air at 350 °C. The coating consisted of agglomerates of narrow size distribution around 100 nm. The photoelectrochemical characteristics were evaluated by investigating the changes in the open circuit potential, current transients and impedance characteristics of a Ti/TiO2 electrode upon illumination by UV light in H2SO4 solution and in the oxidation of benzyl alcohol. The electrode was found to be active for photoelectrochemical reactions in the investigated solutions

The effects of a human food additive, titanium dioxide nanoparticles E171, on Drosophila melanogaster - a 20 generation dietary exposure experiment

In this study, fruit flies (Drosophila melanogaster) were exposed to an estimated daily human E171 consumption concentration for 20 generations. Exposure to E171 resulted in: a change in normal developmental and reproductive dynamics, reduced fecundity after repetitive breeding, increased genotoxicity, the appearance of aberrant phenotypes and morphologic changes to the adult fat body. Marks of adaptive evolution and directional selection were also exhibited. The larval stages were at a higher risk of sustaining damage from E171 as they had a slower elimination rate of TiO2 compared to the adults. This is particularly worrisome, since among the human population, children tend to consume higher daily concentrations of E171 than do adults. The genotoxic effect of E171 was statistically higher in each subsequent generation compared to the previous one. Aberrant phenotypes were likely caused by developmental defects induced by E171, and were not mutations, since the phenotypic features were not transferred to any progeny even after 5 generations of consecutive crossbreeding. Therefore, exposure to E171 during the early developmental period carries a higher risk of toxicity. The fact that the daily human consumption concentration of E171 interferes with and influences fruit fly physiological, ontogenetic, genotoxic, and adaptive processes certainly raises safety concerns

Urban tourist motivations: why visit Ljubljana?

Purpose: The aim of this paper is to develop a new perspective on urban tourist motivations by applying the Analytic Hierarchy Process (AHP) model to help to understand how tourists make decisions about which destinations to visit. Method: This study was based on 30 1-hour long structured interviews with visitors to Ljubljana, the capital city of Slovenia. Respondents were asked to express their preferences between different pull-factor motives for their visit, using Saaty’s scale, and further qualitative data was collected to examine these preferences in more depth. Findings: The results of this study indicate that the most relevant criteria and thus predominant factors in motivation for visits to Ljubljana are the Cultural and Nightlife pull-factors, while Religious and Business motives are the lowest ranked factors. The paper argues that the results show the value of applying the AHP model to understand the role of pull-factors in urban tourism destination choice. Research limitations/implications: As a single-destination case study, it is important that the findings of this research are evaluated against similar studies in other cities. A limitation of this research is the fact that sub motives within major groups of pull-factor motives have not been explored in this study and this should be the subject of future, more detailed research. Originality/value: This research shows the value of applying, AHP, an under-used method to understand urban tourist motivations. The new knowledge gained through applying this method is of value to destination marketing organisations as well as to researchers conducting future studies, who will be able to replicate it and test its value

Poli(uretan-siloksani) na bazi hiperrazgranatog poliestra kao umreživača - sinteza i karakterizacija

A series of novel polyurethane crosslinked structures (PUs) was prepared from α,ω-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO), 4,4'-methylenediphenyl diisocyanate and Boltorn ® hyperbranched polyester of the third pseudo generation. The hydroxyfunctional hyperbranched aliphatic polyester with 26 end groups was used as a crosslinking agent. In order to improve the compatibility of all the reactants during the synthesis, the PU samples were prepared by two-stage, step-growth polymerization in solution. The content of the soft EO-PDMS-EO segments was varied in the range from 15 to 40 wt. %. The influence of the EO-PDMS-EO content on the swelling behavior, crosslink density, hardness, and the thermal and surface properties of the synthesized PUs was investigated. The structure of the synthesized polyurethanes was confirmed by the presence of specific bands in the Fourier transform infrared spectra. Swelling studies were performed to determine the crosslink density and polyurethane networks with lower EO-PDMS-EO contents had higher crosslink densities. The glass transition temperature of the synthesized PUs, determined by differential scanning calorimetry, slightly increased from 50 to 58°C on decreasing the EO-PDMS-EO content because of the higher crosslink density of the samples. Increasing the EO-PDMS-EO content led to better thermal stability, as was evidenced by the onset temperature of weight loss. The surface of the polyurethane networks became more hydrophobic with increasing EO-PDMS-EO content. The surface morphology of synthesized polyurethanes was analyzed by scanning electron microscopy.U ovom radu prikazana je sinteza, struktura i neka svojstva novih umreženih poliuretana pripremljenih polazeći od α,ω-dihidroksi-(etilenoksid-poli(dimetilsiloksan)-etilenoksid) pretpolimera (EO-PDMS-EO), 4,4'-metilendifenildiizocijanata i Boltorn® hiperrazgranatog poliestra treće pseudo-generacije. Hiperrazgranati hidroksi funkcionalni alifatski poliestar sa 26 krajnjih grupa služio je kao umrežavajući agens pri sintezi poliuretana. U cilju poboljšanja kompatibilnosti reaktanata tokom sinteze, poliuretani su sintetisani dvostepenom polimerizacijom u rastvoru. Sadržaj mekog EO-PDMS-EO segmenta variran je u opsegu od 15 do 40 mas. %. Ispitan je uticaj EO-PDMS-EO sadržaja na ponašanje pri bubrenju, gustinu umrežavanja, tvrdoću, termička i površinska svojstva sintetisanih poliuretana. Struktura sintetisanih poliuretana potvrđena je FTIR spektroskopijom. Ponašanje pri bubrenju je ispitivano kako bi se odredila gustina umrežavanja i pokazano je da poliuretanske mreže sa nižim EO-PDMS-EO sadržajem imaju veću gustinu umrežavanja. Rezultati diferencijalne skenirajuće kalorimetrije pokazali su povećanje temperature ostakljivanja poliuretana od 50 do 58°C sa smanjenjem EO-PDMS-EO sadržaja kao posledicu veće gustine umreženosti uzoraka. Sintetisani poliuretani sa većim sadržajem EO-PDMS-EO segmenata pokazuju bolju termičku stabilnost, što je potvrđeno porastom početne temperature degradacije, određene TG analizom. Hidrofobnost površine poliuretana je rasla sa povećanjem sadržaja EO-PDMS-EO u odgovarajućem uzorku. Površinska morfologija sintetisanih poliuretana je analizirana skenirajućom elektronskom mikroskopijom