Nanoparticles: Potential for Use to Prevent Infections

One of the major issues related to medical devices and especially urinary stents are infections caused by different strains of bacteria and fungi, mainly in light of the recent rise in microbial resistance to existing antibiotics. Lately, it has been shown that nanomaterials could be superior alternatives to conventional antibiotics. Generally, nanoparticles are used for many applications in the biomedical field primarily due to the ability to adjust and control their physicochemical properties as well as their great reactivity due to the large surface-to-volume ratio. This has led to the formation of a new research field called nanomedicine which can be defined as the use of nanotechnology and nanomaterials in diagnostics, imaging, observing, prevention, control, and treatment of diseases. For example, coverings or coatings based on nanomaterials are now seen as a promising strategy for preventing or treating biofilms formation on healthcare kits, implants, and medical devices. Toxicity, inappropriate delivery, or degradation of conventionally used drugs for the treatment of infections may be avoided by using nanoparticles without or with encapsulated/immobilized active substances. Most of the materials which are used and examined for the preparation of the nanoparticles with encapsulated/immobilized active substances or smart reactive nanomaterials with antimicrobial effects are polymers, naturally derived antimicrobials, metal-based and non-metallic materials. This chapter provides an overview of the current state and future perspectives of the nanoparticle-based systems based on these materials for prevention, control, or elimination of biofilm-related infections on urinary stents. It also addresses manufacturing conditions indicating the huge potential for the improvement of existing and development of new promising stent solutions

Effects of selenium nanoparticles on pathogenic and probiotic food bacteria, and their influence on human intestinal cells

Selenium is an especially important element for the functioning of antioxidative enzymes, making it one of the essential micronutrients. Although selenium is required in extremely small amounts, often it is lacking from the organism. However, inorganic and organic sources of selenium are known to possess considerable toxicity. Recently, the nanoparticle form of selenium has been shown to exhibit lesser toxicity, and also better antimicrobial and other biological effects, than selenium-containing compounds. Nanotechnology has already found application in many fields, for improving material properties for various purposes, among them, in the process of improving food characteristics. It is possible that selenium nanoparticles can be applied as antimicrobial agents in food, and there has been growing interest in this area of research. We have synthesized selenium nanoparticles (SeNPs) by chemical reduction method, using sodium selenite, ascorbic acid, and bovine serum albumin. The antimicrobial activity of these particles has been assessed by minimum inhibitory concentration assay and colony-forming units count, on Listeria monocytogenes and Salmonella enterica, which are common bacterial food contaminants. As intestinal microbiota, especially probiotic bacteria, have been shown to play important role in organism functioning, we also tested how SeNPs influence Lactobacillus rhamosus and Lactobacillus plantarum. To evaluate cytotoxicity, we used MTT assay on the human intestinal cell line (HT-29). Antioxidative properties were assessed by DPPH assay. SeNPs showed higher antibacterial activity on pathogenic bacteria than on probiotic strains. Cytotoxic effect was present only in the highest tested concentrations. The antioxidative activity was considerable, resulting in above 80% reduction of DPPH free radical, at 1 g/ml of SeNPs. Based on these results, SeNPs are a promising subject for further research in developing materials for food packaging or as antimicrobial selenium additives

Temperature Sensing Properties of Biocompatible Yb/Er-Doped GdF3 and YF3 Mesocrystals

Y0.8−xGdxF3:Yb/Er mesocrystals with a biocompatible surface and diverse morphological characteristics were successfully synthesized using chitosan-assisted solvothermal processing. Their structural properties, studied using X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and energy dispersive X-ray analysis, were further correlated with the up-conversion emission (λexc = 976 nm) recorded in function of temperature. Based on the change in the visible green emissions originating from the thermally coupled 2H11/2 and 4S3/2 levels of Er3+, the corresponding LIR was acquired in the physiologically relevant range of temperatures (25–50 °C). The detected absolute sensitivity of about 0.0042 °C−1, along with the low cytotoxicity toward both normal human lung fibroblasts (MRC-5) and cancerous lung epithelial (A549) cells, indicate a potential for use in temperature sensing in biomedicine. Additionally, their enhanced internalization in cells, without suppression of cell viability, enabled in vitro labeling of cancer and healthy cells upon 976 nm laser irradiation

Biodiversity of Roncus L. Koch in Montenegro - Roncus teutae n. sp. from Mt. Orjen (Neobisiidae, Pseudoscorpiones)

A single species of Roncus L. Koch, 1873, which was collected in the Baretina Lokva on Mt. Orjen, Montenegro, is new to science (R. teutae n. sp.) and described herein. Its diagnostic characters are illustrated and their distribution is provided. The possible establishment of this species of Roncus is presented briefly in view of the importance and analysis of its diagnostic characters. [Projekat Ministarstva nauke Republike Srbije, br. 173038

Mikrobiologija špilja s područja Istre i Kvarnerskog zaleđa

Cilj ovog rada bio je provesti preliminarna istraživanja brojnosti heterotrofnih mikroorganizama u zraku i na površinama stijena u speleološkim objektima. Istraživanje je provedeno na pet objekata na područja Istre i Kvarnerskog zaleđa koristeći klasične mikrobiološke tehnike (kultivaciju). Rezultati pokazuju trend smanjenja broja bakterija u zraku i na površinama speleoloških objekata s odmicanjem od ulaza, uz odstupanja koja se mogu objasniti pojavama šišmiša, otjecanjima vode, zračnim strujama ili antropogenim utjecajem. Rezultati istraživanja će omogućiti optimizaciju metoda uzorkovanja, uzgoja i određivanja brojnosti bakterija u speleološkim objektima te osnovu za daljnji monitoring mikrobiologije speleoloških objekata

Export Diversification in the CEFTA 2006 Region. A "U" Shape Pattern

The main purpose of this paper is to evaluate patterns among export diversification along with the economic development in the CEFTA 2006 region. The pattern, which is evaluated here, is a hump-shaped pattern, which states that diversification and re-concentration of export and has a „U“shape relationship withGDP per capita. Hump-shaped pattern suggests that countries add products to their export basket during the early stages of economic development, while high-income countries remove goods for which they have lost a comparative advantage. Consequently, countries are slower to specialize in exporting products in which they have a comparative advantage, which leads to a humpbacked appearance. It may be concluded that one of the driving forces for export diversification is certainly GDP per capita, where diversification and later re-concentration take place mainly through extensive margins. On the other hand, intensive margins do follow the same pattern as extensive margins. Furthermore, extensive margins represent export diversification to new markets, where intensive margins present export diversification of new products. Export diversification is closely related to commodity export dependence. The country is considered to be commodity export-dependent when more than 60 percent of its total merchandise exports are composed of commodities. In these terms, countries with lower export diversification usually suffer from slow development, non-diversified economic structures, macroeconomic instability, economic volatility,"Dutch disease", political instability, poor political and economic governance, etc. Empirical studies reveal that export diversification can promote economic growth and reduce economic volatility. Greater diversification of exports contributes to greater resilience to exogenous shocks as well as stronger long-term growth and development of the country.With greater export diversification of products and greater geographical diversification (extensive and intensive margins), the risk of exogenous negative impacts is reduced. To test the U-shaped hypothesis, we used Herfindahl–Hirschman index as a measurement for export diversification. In this paper, we used secondary data from the UNCTADstat database for export. Data for GDP per capita were gathered from the World Bank database. After calculating the mentioned index for export diversification/specialization for CEFTA 2006 region, we presented a link between mentioned indexes with GDP per capita. Our results reject the null hypothesis, which states that there is a U-shaped relationship between export diversification and GDP per capita in the CEFTA 2006 region. In the CEFTA 2006 region, countries do not follow the path of higher diversified export at lower GDP per capita, and later specialization in exporting products with an increase of GDP per capita, in a product that which they have comparative advantages. The examined period in this paper was from 2007 to 2020 (13 years). Future studies could examine what the main drivers for export diversification are in CEFTA 2006 region. Also, it would be interesting to examine which margins, extensive or intensive, are the main drivers for diversification and later re-concertation at an individual level of each country

CROATIAN STUDENTS\u27 HABITS IN FAST FOOD CONSUMPTION

Provedeno je on-line anketno ispitivanje na uzorku od 659 hrvatskih studenata o njihovim navikama vezanim uz objedovanje i potrošnju brze hrane. Rezultati istraživanja pokazuju da ispitanici najčešće konzumiraju brzu hranu nekoliko puta mjesečno (42%), uglavnom za ručak (48,7%), pri čemu najčešće odabiru pizzu (79,7%). Najvažnija obilježja brze hrane za ispitanike su okus (srednja vrijednost na Likertovoj ljestvici od 5 stupnjeva je 4,68) i miris (srednja vrijednost 4,38). Istraživanjem je utvrđena povezanost između učestalosti konzumiranja brze hrane i stručne spreme roditelja, prosječnog mjesečnog džeparca i dobi ispitanih studenata, kao i prehrambenih navika ispitanih studenata. Spol utječe na odabir pojedinih jela i namirnica brze hrane, muškarci učestalije konzumiraju hamburger, ćevape i kebab, dok žene češće jedu pomfrit. Na temelju rezultata istraživanja preporuča se edukacija studenata i njihovih roditelja o važnosti zajedničkog objedovanja u krugu obitelji, kao i o štetnom učinku učestale potrošnje brze hrane na zdravlje. Rezultati istraživanja značajni su za zdravstvene organizacije koje se svakodnevno bore protiv porasta potrošnje brze hrane među mladima, kao i za unapređenje aktivnosti u marketingu hrane.An on-line survey was conducted on a sample of 659 respondents regarding the habits of Croatian students in fast food consumption and nutrition habits. The research results have shown that the respondents most frequently consume fast food several times a month (42%), mainly for lunch (48,7%); when they consume fast food, pizza is the meal they choose most often (79,7%). The most significant characteristics of fast food for the respondents are taste (mean value on Likert scale being 4.68) and smell (mean value 4.38). The study has shown a connection between the frequency of eating fast food and the respondents\u27 parents\u27 level of education, the average monthly pocket money and the age of the surveyed students, as well as eating habits of the surveyed students. Gender influences the choice of certain fast food items; thus men frequently consume burgers, minced meat rolls and kebabs, while women are more likely to consume French fries. Based one the results of the survey, education of students and their parents about the importance of having their meals together is highly recommended, as well as the education about the harmful effects on health due to frequent consumption of fast food. The research results are significant for health care organizations that daily struggle against the rise of fast food consumption among the young, as well as to promote activities in the food marketing

Odnos konkurentnosti i priliva SDI u Srbiji i potpisnicama CEFTA 2006 sporazuma

Cilj ovog istraživanja je da analizira i utvrdi postojanje povezanosti između dvanaest stubova konkurentnosti i priliva stranih direktnih investicija u potpisnicima CEFTA 2006 sporazuma. Iako je naučna literatura veoma bogata empirijskim studijama povezanim sa stranim direktnim investicijama, ipak, postoji oskudan broj studija koje se bave ispitivanjem odnosa između stubova konkurentnosti i priliva stranih direktnih investicija. Kako bi se sagledala veza između posmatranih varijabli korišćeni su sekundarni podaci objavljeni od strane međunarodnih organizacija Svetskog ekonomskog foruma za dvanaest stubova konkurentnosti i Svetske banke za SDI. Primenom Pirsonovog koeficijenta korelacije utvrđena je jačina odnosa izmeđa stubova konkurentnosti i priliva SDI za posmatrani vremenski period 2007-2019. godine za potpisnice CEFTA 2006 sporazuma, pri čemu je posebna pažnja posvećena analizi Republike Srbije. Analizom korelacionih koeficijanata na nivou CEFTA 2006 sporazuma utvrđena je značajna pozitivna veza između SDI i sledećih stubova konkurentnosti: razvoja finansijskog tržišta i veličine tržišta, infrastrukture, visokog obrazovanja i obuka, tehnološke spremnosti i veličine tržišta. Sa druge strane, negativni korelacioni koeficijenti stubova konkurentnosti i stranih direktnih investicija su statistički značajni kod stubova koji se odnose na makroekonomsko okruženje i institucije na nivou CEFTA 2006 sporazuma. Pored toga, utvrđena je na nivou Republike Srbije jaka pozitivna veza između SDI i stubova makroekonomsko okruženje, inovacije, visoko obrazovanje i obuke i razvoj finansijskog tržišta. Dodatno, rezultati regresione analize pokazali su da na priliv stranih direktnih investicija u periodu 2007-2016 godine na nivou CEFTA 2006 sporazuma statistički značajno utiču sledeći stubovi konkurentnosti: 1. zdravlje i osnovno obrazovanje; 2. efikasnost tržišta robe; 3. efikasnost tržišta rada; 4. veličina tržišta; 5. inovacije, dok je u periodu 2017-2019. godine statistički značajna bila infrastruktura

Analize voda u speleološkim objektima na području Istre i Kvarnerskog zaleđa

Voda je bitan faktor u nastanku i razvoju speleološkog objekta, stoga je primarna baza ovog istraživanja analiza vode u speleološkim objektima. Preliminarna istraživanja kemije voda provedena su u četiri speleološka objekta; Bačva, Vela peć, Šparožna pećina i Vela špilja u krugu, a kao kontrolna voda korištena je voda iz lokve Višnjana. Voda se u objektima uzorkovala iz kamenica, jezera te voda koja se procjeđivala iz sige. Određivana je ukupna (UT) i karbonatna (KT) tvrdoća vode, pH i električna vodljivost. Uzorcima sa sva tri lokaliteta izmjeren pH je oko neutralnog. Tvrdoća vode je najniža u Veloj peći (kamenica), a i najviša u Bačvi (siga). Najveće vrijednosti UT i KT dobivene su u uzorku vode s iz Bačve, a najmanje iz kamenice u Veloj peći. Ističe se velika razlika između UT i KT kod vode iz kamenice u Bačvi (12,1 i 7,3) i u jezeru Vele peći (11,8 i 6,6). Vrijednost UT i KT vode iz lokve (8,68 i 7,45) uspoređujemo s uzorcima iz objekata jer je voda iz lokveon pod najznačajnijim utjecajem padalina. Električna vodljivost vode također se razlikovala s obzirom na lokalitet uzorkovanja u objektu. Najviša vodljivost izmjerena je u uzorku vode s iz Bačve (0,8 mS/cm), a najniža u kamenici u Veloj veći, Šparožnoj pećini i lokvi. Buduća istraživanja trebala bi se fokusirati na speleološke objekte u različitim litološkim jedinicama te na monitoring istih radi usporedbe i ovisnosti o vremenskim faktorima

Analize voda u speleološkim objektima na području Istre i Kvarnerskog zaleđa

Voda je bitan faktor u nastanku i razvoju speleološkog objekta, stoga je primarna baza ovog istraživanja analiza vode u speleološkim objektima. Preliminarna istraživanja kemije voda provedena su u četiri speleološka objekta; Bačva, Vela peć, Šparožna pećina i Vela špilja u krugu, a kao kontrolna voda korištena je voda iz lokve Višnjana. Voda se u objektima uzorkovala iz kamenica, jezera te voda koja se procjeđivala iz sige. Određivana je ukupna (UT) i karbonatna (KT) tvrdoća vode, pH i električna vodljivost. Uzorcima sa sva tri lokaliteta izmjeren pH je oko neutralnog. Tvrdoća vode je najniža u Veloj peći (kamenica), a i najviša u Bačvi (siga). Najveće vrijednosti UT i KT dobivene su u uzorku vode s iz Bačve, a najmanje iz kamenice u Veloj peći. Ističe se velika razlika između UT i KT kod vode iz kamenice u Bačvi (12,1 i 7,3) i u jezeru Vele peći (11,8 i 6,6). Vrijednost UT i KT vode iz lokve (8,68 i 7,45) uspoređujemo s uzorcima iz objekata jer je voda iz lokveon pod najznačajnijim utjecajem padalina. Električna vodljivost vode također se razlikovala s obzirom na lokalitet uzorkovanja u objektu. Najviša vodljivost izmjerena je u uzorku vode s iz Bačve (0,8 mS/cm), a najniža u kamenici u Veloj veći, Šparožnoj pećini i lokvi. Buduća istraživanja trebala bi se fokusirati na speleološke objekte u različitim litološkim jedinicama te na monitoring istih radi usporedbe i ovisnosti o vremenskim faktorima