Search results for "mines"

Supramolecular Construction of Cyanide-Bridged Re I Diimine Multichromophores

2019

The reactions of labile [Re(diimine)(CO)3(H2O)]+ precursors (diimine = 2,2′-bipyridine, bpy; 1,10-phenanthroline, phen) with dicyanoargentate anion produce the dirhenium cyanide-bridged compounds [{Re(diimine)(CO)3}2CN)]+ (1 and 2). Substitution of the axial carbonyl ligands in 2 for triphenylphosphine gives the derivative [{Re(phen)(CO)2(PPh3)}2CN]+ (3), while the employment of a neutral metalloligand [Au(PPh3)(CN)] affords heterobimetallic complex [{Re(phen)(CO)3}NCAu(PPh3)]+ (4). Furthermore, the utilization of [Au(CN)2]−, [Pt(CN)4]2–, and [Fe(CN)6]4–/3– cyanometallates leads to the higher nuclearity aggregates [{Re(diimine)(CO)3NC}xM]m+ (M = Au, x = 2, 5 and 6; Pt, x = 4, 7 and 8; Fe, x…

Molecular Basis of the Chemiluminescence Mechanism of Luminol

2019

Light emission from luminol is probably one of the most popular chemiluminescence reactions due to its use in forensic science, and has recently displayed promising applications for the treatment of cancer in deep tissues. The mechanism is, however, very complex and distinct possibilities have been proposed. By efficiently combining DFT and CASPT2 methodologies, the chemiluminescence mechanism has been studied in three steps: 1)luminol oxygenation to generate the chemiluminophore, 2)a chemiexcitation step, and 3)generation of the light emitter. The findings demonstrate that the luminol double-deprotonated dianion activates molecular oxygen, diazaquinone is not formed, and the chemiluminopho…

Simultaneous determination of eight underivatised biogenic amines in fish by solid phase extraction and liquid chromatography-tandem mass spectrometr…

2010

Biogenic amines on fish tissue are formed as a result of bacterial contamination and spoilage during storage. A new method based on liquid chromatography (LC) and tandem mass spectrometry (MS/MS) using a triple quadrupole (QqQ) analyser was developed for the analysis of eight biogenic amines (cadaverine, histamine, phenylethylamine, putrescine, spermine, spermidine, tyramine and tryptamine) in fish tissues. Sample preparation was performed by extraction with trichloroacetic acid 5% and solid phase extraction clean up with STRATA X cartridge. The MS/MS method was validated and compared with a method based on the analysis of dansyl derivatives by LC and fluorescence detector (FD). MS/MS achie…

Chemical speciation of nucleotide 5′-monophosphates in the presence of biogenic amines

2001

The interaction of adenosine-, uridine-, inosine- and guanosine-5’-monophosphates with protonated ethylenediamine, putrescine, cadaverine, spermidine and spermine, was studied potentiometrically, a...

A survey of the main technology, biochemical and microbiological features influencing the concentration of biogenic amines of twenty Apulian and Sici…

2015

Abstract Twenty Apulian and Sicilian cheeses were analysed for their concentrations of eight biogenic amines (BAs), free amino acids, pH, water activity, and subjected to microbiological characterisation. In addition, lactic acid bacteria isolated from cheeses were assayed for their capacity to generate BAs. Principal component analysis was performed to find the effect of different parameters on the distribution of the cheeses. Although short-ripened (≤30 d) cheeses did not show significant BA concentrations, the only BA showing high positive correlation with time of ripening was histamine. Concentration of histidine and, especially, percentage of histidine-decarboxylase bacteria presumably…

The impact of lactic acid bacteria with antimicrobial properties on biodegradation of polycyclic aromatic hydrocarbons and biogenic amines in cold sm…

2017

The influence of surface treatment with lactic acid bacteria (LAB), previously cultivated in an alternative substrate, on the formation of polycyclic aromatic hydrocarbons (PAHs) and biogenic amines (BAs) in cold smoked pork meat sausages was investigated. Moreover, sausages treatment with LAB after the smoking on PAHs content changes was evaluated. Additionally, the inhibitory effects of LAB metabolites on food spoilage bacteria was determined using the agar well diffusion assay method. The metabolites of Pediococcus acidilactici KTU05-7, Pediococcus pentosaceus KTU05-9 and Lactobacillus sakei KTU05-6 strains showed good inhibitory properties against tested pathogenic and food spoilage bac…

Effect of plastic deformation on the anodic electroluminescence accompanying the early stage of electrolytic oxidation of cadmium

1995

Cadmium clusters in CdI2layered crystals: the influence on the optical properties

2007

The influence of overstoichiometric Cd i atoms on the optical properties of cadmium iodide layered crystals has been investigated. The results of optical absorption, luminescence, and luminescence excitation studies of CdI 2 crystals with controlled deviation from stoichiometric composition allow observing correlations between the Cd i concentration and features in absorption and emission spectra up to concentrations of 10 18 cm -3 . At higher concentrations the overstoichiometric cadmium atoms form clusters, which were observed using scanning electron microscopy. The extinction spectra of (CdI i ) n clusters are calculated in the frame of Mie theory and are found to correlate with the opti…

Calibration transfer in chemiluminescence analysis

2001

Abstract Direct standardization (DS) and piecewise direct standardization (PDS) methods are applied to multivariate standardization of chemiluminescence signals using PLS model as the calibration model. The linear concentration interval of the chemiluminescence determination was determined. This interval was located using univariate robust calibration by least median of squares (LMS) method. The linear calibration model was corroborated by conventional least-squares method. The standardization subset and window size were optimized by means of the prediction residual error sum of squares. Several instrumental sources of variability have been studied: the detection cell, instrument, batch ver…

Isoprenylhydroquinone glucoside: a new non-antioxidant inhibitor of peroxynitrite-mediated tyrosine nitration

2004

Abstract Three hydroquinone glucosides and four caffeoylquinic esters were examined for their effect on tyrosine nitration, as well as on the oxidation of dihydrorhodamine (DHR) 123 and cytochrome c 2+ induced by peroxynitrite. All these phenolics, which had previously been characterized as the active principles of the plant Phagnalon rupestre , were fairly active in preventing the oxidation of DHR 123, though inefficient in the cytochrome c test. While their antioxidant potency is associated with the presence of a caffeoyl moiety, not so an obvious chemical character was correlated to a greater activity against nitration of tyrosine. Here, the highest potency corresponded to 2-isoprenylhyd…