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61.
In this paper, a set of formulae for the temporal spontaneous baroreceptor reflex (sBRR) sequence parameters in isodistributional (ID) surrogate data is derived. This is facilitated by representing successive positive or negative amplitude changes as a Markov chain model. The obtained analytical tool measures the effect of random fluctuations on the overall number of sequences, estimated from the original biomedical time series. The formulae are tested using ID surrogates of systolic blood pressure and pulse-interval signals recorded from 13 healthy male Wistar rats at baseline conditions. 相似文献
62.
Relić D Đorđević D Sakan S Anđelković I Miletić S Đuričić J 《Journal of hazardous materials》2011,186(2-3):1893-1901
Surface and buried sediments were analyzed for Ba, Ca, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn and V, as well as for total carbon and hydrogen to assess the distribution of sediment pollution due to the vicinity of the petrochemical complex. The samples, collected from 20 locations within the petrochemical complex and from 16 locations outside the complex, were aqua regia extracted and analyzed by ICP/OES. Metals were determined with an acceptable accuracy for certified metals of 82-113%. The precision for the aqua regia extraction was satisfactory, less than 20%, except for Cd where it was 28%. Comparison of the data from the petrochemical with those from the non-petrochemical areas showed different distributions of the metals. Metals that exceeded the baseline range; Ba, Cd, Cu, Zn and Pb, were detected in higher concentrations in sediments that were under the influence of the chlor-alkali plant within the petrochemical complex. Comparison with data from the petrochemical complex and its surroundings and their distribution demonstrated that the metal compositions of the sediments were modified by anthropogenic activities. 相似文献
63.
Dragana Živković Duško Minić Dragan Manasijević Nadežda Talijan Iwao Katayama Ana Kostov 《Journal of Materials Science: Materials in Electronics》2011,22(8):1130-1135
Due to the frequent use of Cu as a substrate material in electronics, it is important to understand the interactions between
the solders and the substrates, based on the knowledge of the phase equilibria, thermodynamics and other characteristics of
the Bi–Cu–Sn system. The results of thermodynamic analysis and characterization of Bi–Cu–Sn alloys as advanced lead-free solder
materials for high temperature application are presented in this paper. The research includes analytical investigations done
by thermodynamic predicting according to general solution model in temperature range 1,073–1,273 K and experimental investigations
performed by differential thermal analysis, differential scanning calorimetry, optical microscopy, hardness and electroconductivity
measurements for the sections with molar ratio Bi:Cu = 1:1, 1:3 and 3:1. 相似文献
64.
van Delft KM Eijkel JC Mijatovic D Druzhinina TS Rathgen H Tas NR van den Berg A Mugele F 《Nano letters》2007,7(2):345-350
We describe a microfabricated Fabry-Pérot interferometer with nanochannels of various heights between 6 and 20 nm embedded in its cavity. By multiple beam interferometry, the device enables the study of liquid behavior in the nanochannels without using fluorescent substances. During filling studies of ethanol and water, an intriguing filling mode for partially wetting water was observed, tentatively attributed to the entrapment of a large amount of gas inside the channels. 相似文献
65.
Vladimir M. Nikolic Dragana L. Zugic Ivana M. Perovic Aleksandra B. Saponjic Biljana M. Babic Igor A. Pasti Milica P. Marceta Kaninski 《International Journal of Hydrogen Energy》2013
In this contribution, we present results of electrochemical characterization of prepared tungsten carbide supported palladium and platinum and Vulcan XC-72 supported palladium. These catalysts were employed as anode catalysts in PEMFC and results are compared to commercial platinum catalyst. Platinum seems to be irreplaceable as a proton exchange membrane fuel cell (PEMFC) catalyst for both the anode and the cathode, yet the high price and limited natural resources are holding back the commercialization of the PEMFCs. Tungsten carbide is recognized as promising catalyst support having the best conductivity among interstitial carbides. Higher natural resources and significantly lower price make palladium good candidate for replacement of the platinum catalyst. The presented results show that all prepared catalysts are very active for the hydrogen oxidation reaction. Linear sweep voltammetry curves of Pd/C and Pd/WC show existence of peaks at 0.07 V vs. RHE, which is assigned to absorbed hydrogen. H2|Pd/WC|Nafion117|Pt/C|O2 fuel cell has almost the same efficiency and similar power output as commercial platinum catalyst. 相似文献
66.
Ivan M. Dugandžić Dragana J. Jovanović Lidija T. Mančić Olivera B. Milošević Scott P. Ahrenkiel Zoran V. Šaponjić Jovan M. Nedeljković 《Materials Chemistry and Physics》2013
Spherical, submicronic TiO2 powder particles were prepared in the low temperature process of ultrasonic spray pyrolysis (150 °C) by using as a precursor aqueous colloidal solutions consisting of surface modified 45 Å TiO2 nanoparticles with dopamine. Detailed structural and morphological characterization of colored submicronic TiO2 spheres was performed by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), laser particle size analysis and FTIR techniques. Also, optical characterization of both dopamine-modified TiO2 precursor nanoparticles and submicronic TiO2 powder particles was performed using absorption and diffuse reflectance spectroscopy, respectively. A significant decrease of the effective band gap (1.9 eV) in dopamine-modified TiO2 nanoparticles compared to the band gap of bulk material (3.2 eV) was preserved after formation of submicronic TiO2 powder particles in the process of ultrasonic spray pyrolysis under mild experimental conditions. Due to the nanostructured nature, surface-modified assemblage of TiO2 nanoparticles preserved unique ability to absorb light through charge transfer complex by photoexcitation of the ligand-to-TiO2 band, conventionally associated with extremely small TiO2 nanoparticles (d < 20 nm) whose surface Ti atoms, owing to the large curvature, have penta-coordinate geometry. 相似文献
67.
Dragana?D.??etojevi?-SiminEmail author Aleksandra?S.?Veli?anski Dragoljub?D.?Cvetkovi? Sini?a?L.?Markov Jasminka??.?Mr?anovi? Vi?nja?V.?Bogdanovi? Slavica?V.??olaji? 《Food and Bioprocess Technology》2012,5(5):1756-1765
There is inadequate published data referring to bioactivity of lemon balm tea and its Kombucha. The aim of this study, therefore,
was to investigate antimicrobial, antiproliferative, genotoxic, and antigenotoxic potential of lemon balm tea and its Kombucha
with consuming acidity. Antimicrobial activity was determined by agar-well diffusion method. Cell growth effects were determined
in HeLa, MCF7, and HT-29 human tumor cell lines. Genotoxic and antigenotoxic effects were determined using chromosome aberration
assay in Chinese hamster cell line CHO-K1. Differences between control and treated groups were evaluated using analysis of
variance, at significance level of p < 0.05. Kombucha from lemon balm tea (Melissa officinalis L.) exibited antimicrobial activity against prokaryotic microorganisms independently of their cell wall structure (both Gram-positive
and Gram-negative bacteria), while there was no observed activity against eukaryots (yeasts and moulds). There was absence
of genotoxic effects while antigenotoxic effects of lemon balm Kombucha and tea were confirmed on MMC-damaged CHO-K1 cells.
For the explanation of cell growth effects that were not concentration dependent, concept of hormesis was used. Antiproliferative
activity was lower compared with traditional Kombucha and Satureja montana L. Kombucha, with lemon balm tea showing higher activity than its Kombucha. 相似文献
68.
Dragana Kocevski Muying Du Jianquan Kan Chengjun Jing Ines Lačanin Hrvoje Pavlović 《Journal of food science》2013,78(5):M731-M737
Antifungal activity of Allium tuberosum (AT), Cinnamomum cassia (CC), and Pogostemon cablin (Patchouli, P) essential oils against Aspergillus flavus strains 3.2758 and 3.4408 and Aspergillus oryzae was tested at 2 water activity levels (aw: 0.95 and 0.98). Main components of tested essential oils were: allyl trisulfide 40.05% (AT), cinnamaldehyde 87.23% (CC), and patchouli alcohol 44.52% (P). The minimal inhibitory concentration of the plant essential oils against A. flavus strains 3.2758 and 3.4408 and A. oryzae was 250 ppm (A. tuberosum and C. cassia), whereas Patchouli essential oil inhibited fungi at concentration > 1500 ppm. The essential oils exhibited suppression effect on colony growth at all concentrations (100, 175, and 250 ppm for A. tuberosum; 25, 50, and 75 for C. cassia; 100, 250, and 500 for P. cablin essential oil). Results of the study represent a solution for possible application of essential oil of C. cassia in different food systems due to its strong inhibitory effect against tested Aspergillus species. In real food system (table grapes), C. cassia essential oil exhibited stronger antifungal activity compared to cinnamaldehyde. 相似文献
69.
Two series of nanoclay reinforced, thermoresponsive hydrogels were prepared, one based on poly(N‐isopropylacrylamide) (PNIPA) and the other on semi‐interpenetrating networks containing PNIPA and poly(N‐vinyl pyrrolidone) (PVP), designated as SIPNs. The gels were crosslinked with 1, 3, and 5 wt % inorganic clay (hectorite) and SIPN gels additionally contained 1 wt % of PVP. The hydrogels were tested in the “as‐prepared state,” i.e., at 10 wt % PNIPA concentration in water and at equilibrium (maximum) swelling. Increasing the concentration of nanoclays increases crosslink density, modulus, tensile strength, elongation (except in equilibrium swollen gels), hysteresis and with decreases in the degree of swelling, broadening of the phase transition region, and a decrease in elastic recovery at high deformations. The presence of linear PVP in the networks increases porosity and the pore size, increases swelling, deswelling rates, and hysteresis, but decreases slightly lower critical solution temperature (LCST), tensile strength, elongation, and elastic recovery. The strongest hydrogels were ones with 10 wt % PNIPA and 5 wt % of nanoclays, displaying tensile strengths of 85 kPa and elongation of 955%. All properties of hydrogels at the equilibrium swollen state are lower than in the as‐prepared state, due to the lower concentration of chains per unit volume, but the trends are preserved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
70.
Jelena B. okovi Sanela M. Savi Jelena R. Mitrovi Ines Nikolic Bojan D. Markovi Danijela V. Randjelovi Jelena Antic-Stankovic Dragana Boi Neboja D. Ceki Vladimir Stevanovi Bojan Batini Jovana Aranelovi Miroslav M. Savi Sneana D. Savi 《International journal of molecular sciences》2021,22(15)
The current study describes the experimental design guided development of PEGylated nanoemulsions as parenteral delivery systems for curcumin, a powerful antioxidant, as well as the evaluation of their physicochemical characteristics and antioxidant activity during the two years of storage. Experimental design setup helped development of nanoemulsion templates with critical quality attributes in line with parenteral application route. Curcumin-loaded nanoemulsions showed mean droplet size about 105 nm, polydispersity index <0.15, zeta potential of −40 mV, and acceptable osmolality of about 550 mOsm/kg. After two years of storage at room temperature, all formulations remained stable. Moreover, antioxidant activity remained intact, as demonstrated by DPPH (IC50 values 0.078–0.075 mg/mL after two years) and FRAPS assays. In vitro release testing proved that PEGylated phospholipids slowed down the curcumin release from nanoemulsions. The nanoemulsion carrier has been proven safe by the MTT test conducted with MRC-5 cell line, and effective on LS cell line. Results from the pharmacokinetic pilot study implied the PEGylated nanoemulsions improved plasma residence of curcumin 20 min after intravenous administration, compared to the non-PEGylated nanoemulsion (two-fold higher) or curcumin solution (three-fold higher). Overall, conclusion suggests that developed PEGylated nanoemulsions present an acceptable delivery system for parenteral administration of curcumin, being effective in preserving its stability and antioxidant capacity at the level highly comparable to the initial findings. 相似文献