Composition and Morphology Investigation of NiCoB Nanoparticles, as-Prepared and Coated by SiO2

NiCoB nanoparticles, as-prepared and coated by SiO2, were synthesized by chemical reduction of metallic salts. The as-prepared samples were additionally annealed at 650 for 1 hour in argon atmos-phere. All samples (the as-prepared and annealed ones) were investigated by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). According to FE-SEM observations each of the investigated samples was composed of nearly spherical nanoparticles with average dimension smaller than 30 nm. Also, tendency of formation of irregular agglomerates was present in both cases of the as-prepared and annealed investigated samples. XRD measurements of as-prepared samples revealed fully amorphous structure. In case of annealed samples, crystallization of different phases was confirmed (as a consequence of heat treatment at 650 C). The existence of these phases was also observed from FE-SEM micrographs as different morphologies present in the samples.(doi: 10.5562/cca2234

The Influence of CuFe2O4 Nanoparticles on Superconductivity of MgB2

AbstractThe influence of CuFe2O4 nanoparticle doping on superconducting properties of Fe-sheated MgB2 wires has been studied. The wires containing 0, 3 and 7.5wt.% of monodisperse superparamagnetic nanoparticles (∼7nm) were sintered at 650°C or 750°C for 1 hour in the pure argon atmosphere. X-ray diffraction patterns of doped samples showed very small maxima corresponding to iron boride and an increase in the fraction of MgO phase indicating some interaction of nanoparticles with Mg and B. Both magnetic and transport measurements (performed in the temperature range 2–42K and magnetic field up to 16 T) showed strong deterioration of the superconducting properties upon doping with CuFe2O4. The transition temperatures, Tc, of doped samples decreased for about 1.4K per wt.% of CuFe2O4. Also, the irreversibility fields Birr(T) decreased progressively with increasing doping. Accordingly, also the suppression of Jc with magnetic field became stronger. The observed strong deterioration of superconducting properties of MgB2 wires is at variance with reported enhancement of critical currents at higher temperatures (determined from magnetization) in bulk MgB2 samples doped with Fe3O4 nanoparticles. The probable reason for this discrepancy is briefly discusse

Microstructural Features of Magnetic NiCoB Nanoparticles Addition to MgB2 Precursor Powders

Magnesium diboride (MgB2) is a superconductor characterized by interesting properties like rather high superconducting transition temperature Tc = 39 K, long coherence length and low anisotropy. In addition, it has a very simple crystal structure and low density. Those properties make the MgB2 an ideal candidate for a wide range of applications. To improve the electromagnetic properties of MgB2, magnetic nickel-cobalt-boron (NiCoB) nanoparticles (mean grain size 17 ± 3 nm) were added to Mg and B precursor powders and sintered at 650 °C, i.e. the temperature of MgB2 superconductor formation. The nearly spherical NiCoB nanoparticles, as-prepared by the chemical reduction of metallic salts, were amorphous according to previous study. The resulting MgB2 sample, formed after the sintering at 650 °C, was subjected to detailed microstructural analysis which included the application of various experimental methods: XRD, FE-SEM, EDS, elemental mapping, TEM and SAED. The methods confirmed the formation of new crystal CoNi phase (due to heat treatment at 650C), consisting of spherical nanoparticles (~ 6 nm) with tendency to spherical agglomerates formation. Those nanosized magnetic particles (characterized by the single domain magnetic structure and blocking temperature TB below room temperature), located at MgB2 grain boundaries, could serve as effective magnetic pinning centers in MgB2, thus improving its electromagnetic properties. This work is licensed under a Creative Commons Attribution 4.0 International License

Indeks ALBI kao prediktor preživljenja nakon resekcije hepatocelularnog karcinoma u bolesnika s kompenziranom cirozom jetre: usporedba s indeksima PALBI i MELD

The aim of the study was to explore predictive value of the ALBI, PALBI and MELD scores on survival in patients resected for hepatocellular carcinoma with compensated liver cirrhosis and no macrovascular infi ltration. In this retrospective study, longitudinal survival analysis was performed. We analyzed patient/tumor characteristics and MELD, ALBI and PALBI scores as liver function tests for predicting survival outcome. Survival was analyzed from the date of liver resection until death, liver transplantation, or end of follow-up. Patients were stratifi ed for age, cirrhosis etiology, presence of esophageal varices, hepatocellular carcinoma stage, microvascular invasion, histologic diff erentiation, and resection margins. We identifi ed 38 patients (alcoholic cirrhosis in 84.2% of patients) resected over an 8-year period. Median preoperative MELD score was 8, ALBI score -2.63, and PALBI score -2.38. During the follow-up period, 24 patients died. Estimated median survival time was 36 months. Microvascular invasion was observed in 33 patients. Higher ALBI score was associated with 23.1% higher relative risk of death. PALBI score was associated with 12.1% higher relative risk of death, whereas MELD score was not associated with the risk of death. In conclusion, ALBI score demonstrated signifi cant predictive capabilities for survival in patients with compensated cirrhosis resected for hepatocellular carcinoma.Cilj je bio istražiti prediktivnu vrijednost zbira ALBI, PALBI i MELD za preživljenje bolesnika s kompenziranom cirozom reseciranih zbog hepatocelularnog karcinoma bez makrovaskularne invazije. Provedena je retrospektivna longitudinalna analiza preživljenja. Testirane su karakteristike bolesnika/tumora kao i jetreni funkcijski testovi MELD, ALBI i PALBI za predviđanje preživljenja. Bolesnici su praćeni nakon resekcije jetre do smrti, transplantacije jetre odnosno do kraja vremena praćenja. Bolesnici su kategorizirani po dobi, etiologiji ciroze, prisutnosti varikoziteta jednjaka, stadiju karcinoma, mikrovaskularnoj invaziji, histološkom stadiju i resekcijskim rubovima. Identifi cirali smo 38 bolesnika (alkoholna ciroza kod 84,2% bolenika) reseciranih kroz razdoblje od 8 godina. Medijan prijeoperacijskog zbira MELD bio je 8, zbira ALBI -2,63 i zbira PALBI -2,38. Tijekom praćenja 24 bolesnika su umrla. Očekivani medijan preživljenja iznosio je 36 mjeseci. Mikrovaskularna invazija pronađena je u 33 bolesnika. Veći ALBI je bio povezan s 23,1%, a PALBI s 12,1% većim relativnim rizikom od smrtnog ishoda. MELD nije bio povezan sa smrtnim ishodom. Zbir ALBI je pokazao značajnu prediktivnu vrijednost preživljenja u skupini bolesnika s kompenziranom cirozom reseciranih zbog hepatocelularnog karcinoma

Synthesis, Structural Characterization and Magnetic Properties of Iron Boride Nanoparticles with or without Silicon Dioxide Coating

Nanoparticles of iron boride (Fe2B, Fe2B coated in SiO2, FexCo2−xB coated in SiO2) were synthesized using the reduction of metal ions by sodium borohydride. X-ray diffraction confirms the amorphicity of the coated compounds and scanning electron microscope imaging revealed the nanoparticulated structure of all compounds. The splitting between zero-field-cooled and field-cooled temperature dependent magnetization curves point to the blocking of superparamagnetic particles magnetization. Magnetic hysteresis loops are however consistent with the combined effects of blocked superparamagnetic and ferromagnetic (multidomain) particles. The observed quite complex magnetic behaviour is in accordance with structural studies, where additional phases and broad distribution of particle sizes were identified

Synthesis, Structural Characterization and Magnetic Properties of Iron Boride Nanoparticles with or without Silicon Dioxide Coating

Nanoparticles of iron boride (Fe2B, Fe2B coated in SiO2, FexCo2−xB coated in SiO2) were synthesized using the reduction of metal ions by sodium borohydride. X-ray diffraction confirms the amorphicity of the coated compounds and scanning electron microscope imaging revealed the nanoparticulated structure of all compounds. The splitting between zero-field-cooled and field-cooled temperature dependent magnetization curves point to the blocking of superparamagnetic particles magnetization. Magnetic hysteresis loops are however consistent with the combined effects of blocked superparamagnetic and ferromagnetic (multidomain) particles. The observed quite complex magnetic behaviour is in accordance with structural studies, where additional phases and broad distribution of particle sizes were identified

Economic aspects of the catering business

Potrebe, kao i očekivanja turista, zahvaljujući globalizaciji kao i razvoju tehnologije neprestano rastu i mijenjaju se. S obzirom na zahtijevnost potražnje potrošača, ugostiteljska ponuda mora se prilagoditi aktualnom turističkom kretanju u svijetu na način da neprestano poboljšava svoje mogućnosti u turističkim jednicima diljem svijeta. Ugostiteljstvo je djelatnost kojoj se pridaje posebna pažnja s obzirom da usluge te djelatnosti značajno utječu na zadovoljstvo turista, odnosno gostiju. U gospodarstvu Republike Hrvatske ugostiteljstvo predstavlja vrlo važnu gospodarsku djelatnost. Ono što ugostiteljstvo čini najperspektivnijom granom gospodarstva jest spektakularan razvoj turizma. Svako hotelsko poduzeće ima svojih pozitivnih i negativnih efekata, no potrebno je provoditi stalna istraživanja i statističke analize kako bi se pozitivne strane mogle i dalje razvijati, a negativne pretvoriti u prednosti. U ovom se radu analiziraju ekonomski aspekti poslovanja ugostiteljskog objekta. Praktični dio rada odnosi se na analizu poduzeća Liburnia Riviera Hoteli d.d. (LRH) koja će detaljnije objasniti ekonomske aspekte poslovanja odabranog ugostiteljskog objekta

Economic aspects of the catering business

Potrebe, kao i očekivanja turista, zahvaljujući globalizaciji kao i razvoju tehnologije neprestano rastu i mijenjaju se. S obzirom na zahtijevnost potražnje potrošača, ugostiteljska ponuda mora se prilagoditi aktualnom turističkom kretanju u svijetu na način da neprestano poboljšava svoje mogućnosti u turističkim jednicima diljem svijeta. Ugostiteljstvo je djelatnost kojoj se pridaje posebna pažnja s obzirom da usluge te djelatnosti značajno utječu na zadovoljstvo turista, odnosno gostiju. U gospodarstvu Republike Hrvatske ugostiteljstvo predstavlja vrlo važnu gospodarsku djelatnost. Ono što ugostiteljstvo čini najperspektivnijom granom gospodarstva jest spektakularan razvoj turizma. Svako hotelsko poduzeće ima svojih pozitivnih i negativnih efekata, no potrebno je provoditi stalna istraživanja i statističke analize kako bi se pozitivne strane mogle i dalje razvijati, a negativne pretvoriti u prednosti. U ovom se radu analiziraju ekonomski aspekti poslovanja ugostiteljskog objekta. Praktični dio rada odnosi se na analizu poduzeća Liburnia Riviera Hoteli d.d. (LRH) koja će detaljnije objasniti ekonomske aspekte poslovanja odabranog ugostiteljskog objekta

Economic aspects of the catering business

Potrebe, kao i očekivanja turista, zahvaljujući globalizaciji kao i razvoju tehnologije neprestano rastu i mijenjaju se. S obzirom na zahtijevnost potražnje potrošača, ugostiteljska ponuda mora se prilagoditi aktualnom turističkom kretanju u svijetu na način da neprestano poboljšava svoje mogućnosti u turističkim jednicima diljem svijeta. Ugostiteljstvo je djelatnost kojoj se pridaje posebna pažnja s obzirom da usluge te djelatnosti značajno utječu na zadovoljstvo turista, odnosno gostiju. U gospodarstvu Republike Hrvatske ugostiteljstvo predstavlja vrlo važnu gospodarsku djelatnost. Ono što ugostiteljstvo čini najperspektivnijom granom gospodarstva jest spektakularan razvoj turizma. Svako hotelsko poduzeće ima svojih pozitivnih i negativnih efekata, no potrebno je provoditi stalna istraživanja i statističke analize kako bi se pozitivne strane mogle i dalje razvijati, a negativne pretvoriti u prednosti. U ovom se radu analiziraju ekonomski aspekti poslovanja ugostiteljskog objekta. Praktični dio rada odnosi se na analizu poduzeća Liburnia Riviera Hoteli d.d. (LRH) koja će detaljnije objasniti ekonomske aspekte poslovanja odabranog ugostiteljskog objekta

Significant reduction of critical current anisotropy in malic acid treated MgB2 tapes

The anisotropy of the critical current density, the n-factor and the irreversibility field of mono-core in-situ MgB tapes have been studied at various magnetic field orientations and temperatures. Undoped as well as silicon carbide (SiC) and malic acid (CHO) added tapes were studied. The anisotropy is noticeably influenced by the additives due to different carbon contents and fabrication processes. The malic acid added tape exhibits almost isotropic behavior compared to SiC doped MgB tapes due to the homogeneous carbon substitution through the chemical solution route, which paves the way to design MgB tapes to be applied for industrial magnet application