Evaluation of Decision-Making Bodies in Insurance Companies in the Republic of Serbia With the Aim of Realistic Presentation of Insurance Costs Using T-Test and Correlation Analyses

The authors presented the results of forecasting the total cost of the company in relation to insurance in large and medium-sized companies in the Republic of Serbia by applying multiple linear regression. This was done based on the evaluated six factors of influence after the evaluations received by the management of the administrative bodies of four insurance companies operating in the Republic of Serbia. The coefficient of determination (R2) of 0.441 was obtained by regression analysis, based on which it can be seen that a value of 44.1% of the total variance is obtained based on the given prediction model. The obtained model is statistically significant, because its significance (p<0.0005, F=19.442) is lower than the observed statistical level. Therefore, a company’s total insurance costs can be predicted based on six influencing factors. Then, the individual contribution of each independent variable to the prediction of the company’s total cost of insurance was observed. For the prediction of the total cost of the company, all independent factors make a significant contribution, except for the analyzed factor, the satisfaction of the insured (Table 2)

Multicore flower-like magnetite for potential application in cancer nanomedicine

Nanomaterials are intensively researched both from the fundamental aspect due to new properties at the nanoscale, as well as the aspect of their application in many areas of technology. Magnetic nanoparticles (MNPs) are being tested for use in the diagnosis and therapy of diseases. A new field of medicine, Magnetic nanomedicine is primarily based on the application of MNPs as drug carriers, diagnostic agents in Magnetic Resonance Imaging (MRI) and heat generators in magnetic hyperthermia. Among nanoparticles, magnetic nanoplatforms based on iron oxides for cancer diagnosis and therapy (Cancer nanomedicine) are the most researched and clinically tested. This study presents the results of research into the physicochemical properties of iron oxide nanoparticles prepared by the polyol route, as well as their testing for potential applications as agents in magnetic hyperthermia (MH) and radionuclide carriers (vectors) for the diagnosis and therapy of malignant diseases. Multicore iron oxide structures synthesized by the "polyol" method represent clusters of single-core nanoparticles or crystallites. The dimensions of the single core particles are \textasciitilde13.5 nm, while the nanoflowers formed by clustering are \textasciitilde25 nm, depending on the applied synthesis parameters. For targeted medical applications, nanoflowers are coated with different ligands in order to increase colloidal stability and biocompatibility. The best results were by coating MNPs with polyacrylic acid (PAA). The multifunctionality of nanoflowers was investigated by measuring their hyperthermic efficiency for applications in magnetic hyperthermia and radiolabeling with diagnostic (99mTc) and therapeutic radionuclides (177Lu, 90Y). In addition to traditional methods of cancer therapy (surgery, radiotherapy, and chemotherapy), new ways of therapy such as MH are constantly being developed. MH is a therapy based on the property of MNPs that when placed in an alternating (AC) magnetic field, transform the electromagnetic energy of the field into heat. When located inside a tumor, MNPs can locally generate a temperature of 42-46 °C and destroy cancer cells by heat. The hyperthermic efficiency of MNPs is expressed through the Intrinsic Loss Power (ILP) parameter. The measured ILP was 7.3 nHm2/kg which is considered one of the higher reported values found in the literature for iron oxides. Nanoflowers were radiolabeled with 99mTc, 177Lu, and 90Y radionuclides. The in vitro stability of radiolabeling was investigated. Good in vitro stability indicates that the formed radioactive particles can be used simultaneously for bi-modal cancer therapy (MH and radionuclide therapy) or for MH therapy and diagnostics (theranostics), in the case of labeling with 99mTc

Structural and optical properties of HDPE implanted with medium fluences silver ions

The implantation of high-density polyethylene (HDPE) has been conducted using Ag+ ions with energy of 60 keV, achieved fluences 1.5 and 10•1015 ions/cm2. Transmission electron microscopy (STEM) and field emission gun - scanning electron microscopy (FEG-SEM) showed the existence of nanoparticle clusters. X ray photoelectron spectroscopy (XPS) revealed the presence of silver in the sample surface region. The surface topography was studied by atomic force microscopy (AFM), while the surface composition uniformity was analyzed using phase imaging AFM. Optical characterization obtained by spectroscopic ellipsometry (SE) showed changes in refractive index, extinction coefficient and the optical band gap with the fluence of implanted ions

Outputand perfomance based road maintenance contracting – case study Serbia

U radu se opisuju glavne karakteristike ugovora o održavanju i popravku cesta prema Output and Performance-Based Contracting for Roads (OPBC). Daje se pregled iskustava u primjeni takvih ugovora. Agencije za održavanje cesta koje su prihvatile OPBC pristup uštedjele su od 10 % do 40 % u cijeni radova u usporedbi s radovima ugovorenim po tradicionalnoj metodi. U razdoblju od 2004. do 2008. u Srbiji je bio primijenjen način ugovaranja prema Output Performance-based Maintenance Contract (OPBC) za pilot projekt u okviru Transport Rehabilitation Project-a financiranog od Svjetske banke. Prikazani su glavni rezultati i zaključci.The paper describes the main features of contract work for road maintenance and improvement under the Output and Performance-Based Contracting for Roads (OPBC). Experiences in the application of such contracts for the roads are reviewed. Road agencies that have adopted an OPBC approach have achieved cost savings from 10 % to 40 % compared to traditional method-based contracts. During the period 2004 ÷ 2008 Serbia implemented the Output Performance-based Maintenance Contract (OPBC) for routine road maintenance pilot project within Transport Rehabilitation Project financed by World Bank. The main results and conclusions are presented

Preparation and Performance of Low Content Carbon Geopolymer

Due to the low CO2 emission of geopolymers compared to Portland cement, interest in their use as binding cement has increased in recent years. The main goal of this research is to relate the green and sustainable characteristics to the good mechanical and chemical properties of fly ashbased geopolymers. For those purposes, samples of different ratios of fly ash (FA) and metakaolin (MK) were prepared. Mineralogical characterization of the geopolymer samples conducted using X-ray powder diffraction (XRD) showed that in the geopolymer synthesis reaction new amorphous phase was formed. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) confirmed characteristic bands of Si-O and O-Si-O groups at 1045 cm–1 . Compressive strength analysis revealed that the optimal ratio of FA and MK is 50:50 and exhibits the highest value, while X-ray photoelectron spectroscopy (XPS) analysis revealed the total reduction of carbon content in the alkali activated geopolymer with optimal stoichiometry 50:50. The results of this research indicates the possibility to obtain a geopolymer material with almost complete absence of carbon, which implies further application as a material with very high environmental potential and zero carbon emission

Alkali activation of different type of ash as a production of combustion process

Presented study deals with the final structure and radiological properties of different fly-ash based geopolymers. Lignite fly-ash (lignite Kolubara – Serbia) and wood fly ash were obtained in combustion process together with commercial fly-ash. Synthesis of the geopolymers was conducted by mixing fly-ash, sodium silicate solution, NaOH and water. The samples were strengthened 60 °C for 48 hours after staying at room temperature in covering mold for 24 hours. The X-ray diffraction, Fourier transform infrared and SAM measurements were conducted on the samples after 28 days of geopolymerization process. The X-ray diffraction measurements of lignite fly-ash samples show anhydrite as the main constituent, while wood fly-ash samples consist of calcite, albite and gypsum minerals. Besides determination of physicochemical properties, the aim of this study was radiological characterization of lignite fly-ash, wood fly-ash and the obtained geopolymer products. Activity concentration of 40K and radionuclides from the 238U and 232Th decay series, in ash samples and fly-ash based geopolymers, were determined by means of gamma-ray spectrometry, and the absorbed dose rate, D, and the annual effective dose rate, E, were calculated in accordance with the UNSCEAR 2000 report

Mechanochemical treatment and structural properties of lead adsorption on kaolinite (Rudovci, Serbia)

In the present work, remediation of lead-containing solution using raw and modified kaolinite has been presented. The micro and nanostructure of samples has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Laser diffraction and scattering (LDS), was analyzed by particle size analyzer based on laser diffraction and particle size distribution (PSD) was done. The degree of metal adsorption was evaluated analyzing the Pb(II) contaminated samples by inductively coupled plasma atomic emission spectrometry (micro- and nanostructure on immobilization efficiency correlCP AES). The results show the impact of immobilization efficiency and ation between micro- and nanostructure. The thermodynamic data (Delta HA degrees, Delta SA degrees, Delta GA degrees) are calculated from the temperature-dependent sorption isotherms. The results suggest sorption process of Pb(II) on kaolinite as spontaneous and endothermic

Radiolabeled surface-modified single-core (Mg,Fe)3O4 colloidal nanoparticles as vectors in radionuclidetherapy of cancer

A series of MgxFe3-xO4 (x=0, 0.1, 0.2, 0.4, 0.6, 0.8, and 1) magnetic nanoparticles (MNP) were synthesized by a two-step procedure, a co-precipitation method followed by hydrothermal treatment in a microwave field. The MNP are single-core, with crystallite size gradually decreasing from 15.5(3) up to 2.5(3) nm with an increase ofx. TEM images show pseudospherical log-normally distributed particles with an average particle diameter of 19.8 nm and a polydispersity index of 26.1% for magnetite. The particle diameter decreases with the increase of magnesium (x) in the formula unit. The colloidal stability of MNP was achieved by their surface modification with citric acid (CA), oleic acid (OA) and polyethylene glycol (PEG). The cytotoxic activity of uncoated and coated Mg0.6Fe2.4O4 was tested against target malignant cells (HeLa, LC174, A549) and normal MRC5 cells. The investigated MNP show moderate cytotoxic activity against the tested malignant cells in vitro. In contrast, MNP didn’tshow any significant cytotoxic effect against normal cells. HeLa cells exhibited the highest susceptibility among the malignant cells. Mg0.6Fe2.4O4@OA show good cytotoxic activity against all examined malignant cells, significantly higher than other tested MNP. It can be seen that Mg0.6Fe2.4O4@PEG show a lower cytotoxic activity compared to all analyzed MNP. A direct method was used for labeling with radionuclide 90Y, which involves incubation of MNP with 90Y at a certain temperature and time. The labeling yield of the 90Y-coated MNP was determined by analyzing the radiochemical purity after labeling. 90YMg0.2Fe2.8O4@PEG were labeled in high yield (100%), while the yield for 90YMg0.2Fe2.8O4@CA was 83%. In vitro stability of 90Y-coated MNP at room temperature in physiological solution and human serum was monitored within 72 h from the moment of labeling by determining the radiochemical purity of ITLC-SG by radio chromatographic method. The stability of 90Y-Mg0.2Fe2.8O4@PEG was about 97%, while 90Y-Mg0.2Fe2.8O4@CA stability was 73%. The results of this study indicate that radiolabeled surface-modified (Mg, Fe)3O4 can be used as vectors in radionuclide therapy of malignant diseases

Engineering multi-core flower-like magnetic nanoparticles with high intrinsic loss power

In the last decades, self-heating magnetic nanoparticles (MNPs) were engineered and investigated for magnetic hyperthermia (MH) and other applications such as catalysis and chemical synthesis. To be applied as nanoheaters for in vivo MH in cancer therapy, MNPs should have high heating efficiency expressed by Intrinsic Loss Power (ILP). One of the requirements for in vivo applications of MNPs is their non-toxicity. Hence, the most investigated MNPs for MH are based on iron oxides (magnetite and maghemite), which are non-toxic or slightly toxic. This work aimed to apply thepolyol-mediated protocol to engineer mixed Zn1-xMnxFe2O4 and analyze their heating abilities. To obtain a series of Zn1-xMnxFe2O4 samples with a specific nominal composition, the initial components, salts of Zn, Mn and Fe, were mixed in the appropriate stoichiometric ratio. The deviation from the target stoichiometry and the formation of samples with polyvalent ions and possibly vacancies were determined after ICP analysis. By analyzing TEM micrographs, we found that the change in the chemical composition does not affect the morphology. Multicore flower-like nanostructures with a size in the range of 47-63 nm were obtained. They consist of many cores (crystallites or nanoparticles) with a size of \textasciitilde10 nm. The samples show good colloidal stability, which is significant for their medical applications. Magnetization measurements in different DC fields showed that the samples are superparamagnetic at 300K and that the saturation magnetization values are in the range of \textasciitilde59-73 emu/g. The hyperthermic efficiency of the synthesized samples was tested in an external ac field of 252 kHz and a field strength of 15.9 kA/m. Significantly different values were obtained for the ILP parameter (in units nHm2/Kg): 5.77 (Zn0.098Mn0.447Fe2.455O4) ˃ 3.22 (Mn0.624Fe2.376O4) ˃ 2.04 (Zn0.182Mn0.344Fe2.474O4) ˃ 1.36 (Zn0.309Mn0.240Fe2.451O4) ˃ 1.01 (Zn0.394Mn0.138Fe2.468O4) ˃ 0.34 (Zn0.640Fe2.360O4). To explain the values of the ILP parameter, additional research is required, which includes the analysis of the influence of local defects and cation distribution on the magnetism of the investigated nanostructures. Also, significantly high ILP values indicate that some samples can be selected and further tested for in vitro/in vivo applications