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Co-Mo carbides were prepared by impregnation with aqueous solution of metal salts and sucrose into ordered mesoporous SBA-15 silica template using carbothermal hydrogen reduction. Bimetallic Co-Mo carbide obtained by using carbothermal hydrogen reduction of Co-Mo precursors is formed when the Co-Mo molar ratio is 1.0. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Electrochemical characterization of obtained materials wеre performed by cyclic voltammetry in acid solution. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III-45012, Grant no. OI-172045 and Grant no. OI 172035]

Background/Aim. In recent years, many studies have demonstrated a proximal shift in the distribution of adenomas and colorectal cancers. The aim of this study was to investigate whether there are differences in the incidence and anatomical distribution of adenomas and colorectal cancers spanning a 20 year time gap. Methods. We performed a retrospective observational study of colorectal adenomas and cancers diagnosed during total colonoscopy in a high volume tertiary care facility in two 1-year periods of time – 1990 and 2010. Results. During the analyzed period, 4,048 colonoscopies were performed, 1,148 were performed in 1990 and 2,900 were done in 2010. The study included 466 patients with adenomas and 121 patients with colorectal cancers. Frequency of proximal adenoma changed from 16.5% to 32.7% (p < 0.001). By analyzing colonoscopies in 2010, an increase in the incidence of adenomas compared to 1990 was noticed. The number of adenomas sized 0–5 mm rose from 32.8% to 56.9% (p < 0.001). Frequency of colon carcinoma changed from 5.3% to 2.0% (p < 0.001). Incidence of cancers in the proximal colon rose from 21.3% to 48.4% (p = 0.002). A higher incidence of cancers in the proximal colon and a lower incidence of distal cancers were observed, while no difference was observed in the incidence of rectal cancers. Conclusion. Presence of proximal colon adenoma and cancer is higher, while the overall incidence of colon cancer is lower. This finding should be taken into account when planning the screening for colorectal cancer.

Dry micronizing grinding of mineral raw materials is a very complex process and depends on a whole range of parameters such as: shape, particle size, size distribution of the starting and micronized material, hardness, moisture, density, surface properties, structural characteristics of mills, etc. In order to obtain a clear picture of dry micronizing milling process, a good knowledge of the theoretical principles of high-energy mills operation is necessary. Classical mills are not suitable for micronization to a fine and particularly very fine particles size (upper particle size limit below 5 μm), which is necessary for modern industrial application domains. The intensive fundamental and developmental research of the dry micronizing milling process for the new materials development has also enabled the development of new construction solutions for ultra-fine high-energy mills - mechanics. These mills have found application into the state-of-the-art production technologies of new very profitable materials. For the production of powders - particles of micron dimensions, the mechano-actuators are used and all micronizers - disintegrators, colloidal (perl mills), vibratory, planetary, ultra-centrifugal mill, Jet-current mills and others operate on the principle of impact, shock and friction. This paper presents the experimentally achieved results of dry micronizing grinding of zeolites in a vibrating mill with rings, as well as the improvement of its reactivity. All experimental micronization investigations were carried out on a previously prepared coarse particle size class (- 3.35 + 0) mm with different starting mass (50 g and 200 g), and carried out in different grinding time intervals (45, 120, 900 seconds), in order to examine the impact of these parameters on the micronization process. Grinding success was evaluated by the particle size measurements and content of class (- 5 + 0) μm, and particle specific surface. It was shown that for a sample of four times larger initial mass it is need longer grinding time to achieve the maximum content of the class (- 5 + 0) μm, but for a sample of the bulk class (- 3.35 + 0) mm with a lower starting mass the effects of amorphization due to prolonged micronizing grinding are very pronounced, and the zeolite minerals in crystalline form are practically in the trace and the largest part is amorphous. Generally, it can be concluded that a vibrating mill with a rings proved to be a good device for efficient ultra-fine micronizing grinding.

The aim of this work was to examine the possibility of modification of commercial denture base materials with itaconic acid esters, in order to obtain material with less toxicity and higher biocompatibility. Despite their relatively higher price compared to methacrylates, itaconic acid and itaconates are materials of choice for environmentally friendly applications, because they are not produced from petrochemical sources, but from plants. Commercial system based on poly(methyl methacrylate) was modified using ditetrahydrofurfuryl itaconate (DTHFI), wherein the ratio of DTHFI was varied from 2.5 to 10% by weight. Copolymerization was confirmed using FTIR spectroscopy, while SEM analysis showed the absence of micro defects and pores in the structure. The effect of the itaconate content on the absorption of fluids, the residual monomer content, thermal, dynamic-mechanical and mechanical properties (hardness, toughness, stress and elongation at break) was investigated. It was found that the addition of DTHFI significantly reduced the amount of residual methyl methacrylate, what made these materials less toxic. It was shown that the increase in DTHFI content gave materials with decreased glass transition temperature, as well as with decreased storage modulus, ultimate tensile strength and impact fracture resistance, however mechanical properties were in the rang prescribed by ADA standards, and can be used in practice. The deterioration of mechanical properties was therefore worth losing in order to gain lesser toxicity of the leached monomer. [Projekat Ministarstva nauke Republike Srbije, br. 172062: Synthesis and characterization of novel functional polymers and polymeric nanomaterials]

In this work the electrochemical behavior of cobalt ethylendiamine complexes (Co(en)), at pH 12 has been investigated by cyclic voltammetry (CV), potentiostatic pulse technique and polarization curve measurements at stationary and rotating glassy carbon (GC) electrode. It was shown that sixteen different species can be formed in the solution containing Co(en)3 ligand, with the most stable one at all pH values being [Co(en)3]3+. The reduction of [Co(en)3]3+ into [Co(en)3]2+ was shown to be totally irreversible, one-electron exchange reaction. Further reduction of [Co(en)3]2+ was found to be complex process leading to a cobalt deposition at the potentials more negative than -1.45 V vs. SCE. The process of [Co(en)3]2+ oxidation was also complex and most probably coupled with the chemical reaction. [Projekat Ministarstva nauke Republike Srbije, br. 172045]

The experience of the EU in the way of stimulating rural development has been accepted as a starting position in Serbia. The level of economic growth, even in rural areas, despite efforts is not at the desired level. Ways to stimulate rural development process are researched deductively on the example of two municipalities in Sumadija, Serbia. The result of the research pointed to the need to specify the policy of integrated rural development of the municipality and the need to innovate the existing models of organization. It is concluded that the policy of rural municipalities should be directed to: active access to finance, identity politics, and continuing education. Innovation in the organization involves: an Initiative team who prepare the documentation as a basis for decision-making, implementation of agricultural incubator (a symbiosis of business, technology and incubator for a quality management system), and establishing a system of vertical mergers.

In this paper the biodegradation study of grafted copolymers of polystyrene (PS) and corn starch and poly(methacrylic acid) and corn starch in model river water is described. These copolymers were obtained in the presence of different amine activators. The synthesized copolymers and products of degradation were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Biodegradation was monitored by mass decrease and number of microorganisms by Koch’s method. Biodegradation of both copolymers advanced with time, poly(methacrylic acid)-graft-starch copolymers completely degraded after 21 day, and polystyrene-graft-starch partially degraded (45.78-93.09 % of total mass) after 27 days. Differences in the degree of biodegradation are consequences of different structure of the samples, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. The grafting degree of PS necessary to prevent biodegradation was 54 %. Based on experimental evidence, mechanisms of both biodegradation processes are proposed, and influence of degree of starch and synthetic component of copolymers on degradation were established. [Projekat Ministarstva nauke Republike Srbije, br. 172001 i br. 172062]