Determination of phenolic compounds and hydroxymethylfurfural in meads using high performance liquid chromatography with coulometric-array and UV detection

The objective of this study was the determination of 25 phenolic compounds in different mead samples (honeywines) using high performance liquid chromatography (HPLC) with coulometric-array detection and in case of hydroxymethylfurfural with UV detection. Our method was optimized in respect to both the separation selectivity of individual phenolic compounds and the maximum sensitivity with the electrochemical detection. The method development included the optimization of mobile phase composition, the pH value, conditions of the gradient elution and the flow rate using a window-diagram approach. The developed method was used for the determination of limits of detection and limits of quantitation for individual compounds. The linearity of calibration curves, accuracy and precision (intra- and inter-day) at three concentration levels (low, middle and high concentration range) were verified. Mead samples were diluted with the mobile phase at 1:1 to 1:50 ratio depending on the concentration and filtered through a PTFE filter without any other sample pre-treatment. Phenolic compounds concentration was determined in 50 real samples of meads and correlated with meads composition and hydroxymethylfurfural concentration. The most frequently occurred compounds were protocatechuic acid and vanillic acid (both of them were present in 98% samples), the least occurred compounds were (+)-catechin (10% samples) and sinapic acid (12% samples). Vanillin and ethylvanillin, which are used as artificial additives for the taste improvement, were found in 60% and 42% samples, respectively. Hydroxymethylfurfural concentration, as an indicator of honey quality, was in the range from 2.47 to 158 mg/L. Our method is applicable for the determination of 25 phenolic compounds in mead, honey and related natural samples.     

Direct measurement of the formation length of photons

We report the first observation of a shoulder in the radiation spectrum from GeV electrons in a structured target consisting of two thin and closely spaced foils. The position of the shoulder depends on the target spacing and is directly connected to the finite formation length of a low-energy photon emitted by an ultrarelativistic electron. With the present setup it is possible to control the separation of the foils on a μm scale and hence measure interference effects caused by the macroscopic dimensions of the formation length. Several theoretical groups have predicted this effect using different methods. Our observations have a preference for the modified theory by Blankenbecler but disagree with the results of Baier and Katkov.     

Decay properties of low-lying levels in100Rh

Zeitschrift für Physik A Hadrons and nuclei - Low-lying levels of100Rh have been investigated with the reaction100Ru(p, nγ)100Rh in the proton energy range 4.4 MeV≦E p≦6 MeV....     

Theoretical considerations on the cold nuclear fusion in condensed matter

Summary This paper shows that a pseudomesic molecule with two negative quasi-particles of few electron masses could give rise to cold fusion rates comparable with those recently observed. It is also shown that such a condition can be easily reached in Pd-D _x , withx>1 via an 1s-4d orbital hybridization. When these two bands are coupled, electrons involved in the Pd-D-D bonds could have effective mass as large as about 20m _e. This result can explain the observed fusion rates in condensed matter. CISE S.p.A., Tecnologie Innovative, Division of Materials and Technologies     

Fluorescent supramolecular liquid crystalline polymers from nucleobase-terminated monomers

While thymine or N6-(4-methoxybenzoyl)adenine terminated bis(4-alkoxy)-substituted bis(phenylethynyl)benzene monomers show no liquid crystalline behaviour by themselves, mixing the complementary nucleobase monomers together results in the formation of thermotropic liquid crystalline phases.     

Reactive oxygen species produced upon photoexcitation of sunscreens containing titanium dioxide (an EPR study)

Commercial sunscreen products containing titanium dioxide were irradiated with lambda>300 nm and the formation of oxygen- (.OH, O2.-/.OOH) and carbon-centered radicals was monitored by EPR spectroscopy and spin trapping technique using 5,5-dimethyl-1-pyrroline N-oxide, alpha-phenyl-N-tert-butylnitrone (PBN), alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone as spin traps, and free nitroxide radical 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl. The photoinduced production of singlet oxygen was shown by 4-hydroxy-2,2,6,6-piperidine. The generation of reactive oxygen radical species upon irradiation of sunscreens significantly depends on their composition, as the additives present (antioxidants, radical-scavengers, solvents) can transform the reactive radicals formed to less harmful products. The continuous in situ irradiation of titanium dioxide powder, recommended for cosmetic application, investigated in different solvents (water, dimethyl sulfoxide, isopropyl myristate) resulted in the generation of oxygen-centered reactive radical species (superoxide anion radical, hydroxyl and alkoxyl radicals).     

Study of enzymatic reaction by electrophoretically mediated microanalysis in a partially filled capillary with indirect or direct detection

Electrophoretically mediated microanalysis (EMMA), in combination with a partial filling technique and indirect or direct detection, is described for the study of enzymes reacting with the high mobility inorganic or organic anions as substrates or products. Part of the capillary is filled with a buffer optimized for the enzymatic reaction, the rest of the capillary with the background electrolyte being optimal for the separation of substrates and products. With haloalkane dehalogenase, chosen as a model enzyme, the enzymatic reaction was performed in a 20 mM glycine buffer (pH 8.6). Because of the wide substrate specificity of this enzyme, utilizing chlorinated as well as brominated substrates and producing either nonabsorbing chloride or absorbing bromide ions, two different background electrolytes and detection approaches were adopted. A 10 mM chromate-0.1 mM cetyltrimethylammonium bromide background electrolyte (pH 9.2) was used in combination with indirect detection and 20 mM beta-alanine-hydrochloric acid (pH 3.5) in combination with direct detection. The Michaelis constant (K(m)) of haloalkane dehalogenase for 1-bromobutane was determined. The K(m) values 0.59 mM estimated by means of indirect detection method and 0.17 mM by means of direct detection method were comparable with the value 0.13 mM estimated previously by gas chromatography.     

The 0 1 + →0+ electric monopole transition in112Cd

The low-lying levels of¹¹²Cd have been populated in the decay of¹¹²In (T _1/2=14 ^m ) produced through the¹¹²Cd (p, n)¹¹²In reaction atE _p=6.5–7 MeV. The intensity ratio of theE0 toE2K-conversion electrons from the 0 ₁ ⁺ level to the ground (0⁺) and to the first (2⁺) excited state in¹¹²Cd has been measured and the ratioX(E0/E2) =B(E0;0 ₁ ⁺ →0⁺)/B(E2;0 ₁ ⁺ →2⁺) has been determined. The result is compared with the predictions of current macroscopic models.     

A new radical scavenging anthracene glycoside, asperflavin ribofuranoside, and polyketides from a marine isolate of the fungus microsporum

A new anthracene glycoside, asperflavin ribofuranoside (1), and the previously described polyketides, flavoglaucin (2), isodihydroauroglaucin (3), and citrinin (4) have been isolated from the marine-derived fungus Microsporum sp. The structure and absolute stereochemistry of a new compound (1) was assigned on the basis of physicochemical data. Compounds 1-3 exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC(50) values of 14.2, 11.3, and 11.5 microM, respectively, which are more potent than the positive control, ascorbic acid (IC(50), 20 microM). Compound 1 also showed a moderate antibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus (MRSA and MDRSA) with MIC value of 50 microg/ml.     

pH‐Responsive Hybrid Organic–Inorganic Ruthenium Nanoparticles for Controlled Release of Doxorubicin

The current study aims at preparing biocompatible hybrid organic–inorganic ruthenium core–shell nanostructures (RuNPs) coated with polyvinylpyrrolidone (PVP) and polyoxyethylene stearate (POES). Thereafter, the core/shell RuNPs are loaded with doxorubicin (to form RuPDox) with a loading efficiency > 60%. RuPDox possesses exceptional stability and pH‐responsive release kinetics with approx. 50% release of doxorubicin at up to 1 h exposure to an acidic endosomal environment. The cytotoxic effects of RuPDox are tested in vitro against breast cancer (MDA‐MB‐231), ovarian cancer (A2780), and neuroblastoma (UKF‐NB‐4) cells. Notably, although RuNPs have slight cytotoxicity only, RuPDox causes a synergistic enhancement of cytotoxicity when compared to free doxorubicin. Significant increase in free radicals formation, enhanced activity of executioner caspases 3/7, and higher expression of p53 and metallothionein is further identified due to the RuPDox treatment. Single‐cell gel electrophoresis reveals no additional contribution of RuNPs to genotoxicity of doxorubicin. Moreover, RuPDox promotes significantly increased stability of doxorubicin in human plasma and pronounced hemocompatibility assayed on human red blood cells. The results imply a high potential of biocompatible hybrid RuNPs with PVP‐POES shell as versatile nanoplatforms to enhance the efficiency of cancer treatment.