Cyberbullying has become widespread, and is generating growing concerns as it affects students and school climates in general. The objective of this article is to investigate the prevalence of cyberbullying among Serbian adolescents. Special emphasis was placed on gender differences regarding different forms of cyberbullying and victimization. In this study, 387 middle school students from five state schools in Belgrade were surveyed in order to obtain information about the prevalence of cyberbullying and victimization. The results show that most of the students used the Internet on a daily basis and that almost all of them possess their own mobile telephones. On average, 10% of students aged 11-to 15-years-old reported that they have cyberbullied others online, whilst 20% of them were victims of cyberbullying. The most common types of victimization reported by students were denigration and harassment, and most of the cyberbullying took the form of harassment. There were significant gender differences in cyberbullying, with male students reporting higher levels of bullying others and being victimized by cyberbullies than females. Implications for prevention and intervention are presented.

In this study, we have investigated the synthesis of nanoparticles of hydroxyapatite (HAp) and hydroxyapatite coated with chitosan (HAp/Ch) and the chitosan-poly-d,l-lactide-co-glycolide polymer blend (HAp/Ch-PLGA) as an organ-targeting system. We have examined and defined the final destination, as well as the dynamics and the pathways of the synthesized particles following intravenous administration in vivo. The XRD, ZP, FT-IR and SEM analyses have confirmed that the hydroxyapatite nanoparticles with d50=72 nm are coated with polymers. Radioactive 125-Iodine ((125)I), a low energy gamma emitter, was used to develop a novel in situ method for the radiolabeling of particles and investigation of their biodistribution. (125)I-labeled particles exhibited high stability in saline and serum over the second day, which justified their use in the following in vivo studies. The biodistribution of (125)I-labeled particles after intravenous injection in rats differed significantly: HAp particles mostly targeted the liver, HAp/Ch the spleen and the liver, while HAp/Ch-PLGA targeted the lungs. Twenty-four hours post injection, HAp particles were excreted completely, while both (125)I-HAp/Ch and (125)I-HAp/Ch-PLGA were retained in the body for a prolonged period of time with more than 20% of radioactivity still found in different organs.

Radiolabelled superparamagnetic iron oxide nanoparticles (SPIONs) are promising nanomaterial for development of dual radiation/hyperthermia cancer therapy. To that purpose, flower-shaped SPIONs with an exceptional heating capability were synthesised and coated with citrate, dextran or (3-aminopropyl)triethoxysilane. Both non-coated and coated SPIONs were nontoxic to CT-26 mouse colon cancer cells up to 1.0 mg/mL in vitro. In an oscillating magnetic field, citrate-coated SPIONs (CA/SPIONs) displayed the highest heating rate (SAR253 W/g) and strongest hyperthermia effects against CT-26 cells. Labelling of CA/SPIONs by 90Y radionuclide, emitting β− radiation with average/maximum energy of 0.94/2.23 MeV and deep tissue penetration, generated 90Y-CA/SPIONs intended for therapy of solid tumours. However, intravenous injection of 90Y-CA/SPIONs in CT-26 xenografts-bearing mice resulted in low tumour accumulation. Contrary, intratumoral injection resulted in long-term retention at the injection site. A single intratumoral injection of 0.25 mg CA/SPIONs followed by 30-minute courses of magnetic hyperthermia for 4 consecutive days caused a moderate antitumor effect against CT-26 and 4T1 mouse tumour xenografts. Intratumoral application of 1.85MBq/0.25 mg 90Y-CA/SPIONs, alone or combined by hyperthermia caused a significant (P ≤ 0.01) antitumor effect without signs of systemic toxicity. The results confirm suitability of 90Y-CA/SPIONs for monotherapy or dual magnetic hyperthermia-radionuclide nanobrachytherapy (NBT) of solid tumours.

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The concept of community policing is based on constant consultations between the police and the local self-government and a complex system of preventative responses. A qualitative approach has been applied in a rural community based on the analysis of administrative documents from 2003 to 2011, direct observation and a survey examining the attitudes of 65 police officers who participated directly in the project implementation. The major findings include the existence of a centralized police model and traditional policing, the resistance of low and middle managers to change and the absence of continuous consultations between the police and local self-government.