Search results for "PreP"
showing 10 items of 1334 documents
Simulation studies of the laser ablation ion source at the SHIPTRAP setup
2020
Hyperfine interactions 241(1), 46 (2020). doi:10.1007/s10751-020-01708-0
Photoelectrochemical and EPR features of polymeric C 3 N 4 and O-modified C 3 N 4 employed for selective photocatalytic oxidation of alcohols to alde…
2019
Four different C 3 N 4 specimens have been prepared, a bulk one (MCN), a thermally etched (MCN-TE), a solid prepared by hydrothermally treating MCN with H 2 O 2 (MCN-H 2 O 2 ) and a polymeric carbon nitride-hydrogen peroxide adduct (MCN-TE-H 2 O 2 ). The principal aim of this work was to correlate the capability of the prepared material to generate reactive oxygen species (ROS), under irradiation, with their photocatalytic activities in terms of conversion and selectivity for partial oxidation reactions. Photoelectrochemical studies revealed that MCN-TE represented the best material in terms of photoconductivity, whereas MCN-H 2 O 2 was defective and evidenced a poor mobility of carriers. E…
Determination of ochratoxin A in beer marketed in Spain by liquid chromatography with fluorescence detection using lead hydroxyacetate as a clean-up …
2005
Abstract A new sample treatment for liquid chromatographic analysis of ochratoxin A (OTA) in beer is proposed. Degassed beer is mixed with lead hydroxyacetate, which precipitates some bulk components but does not remove OTA. The precipitate is separated and the acidified liquid is extracted with chloroform. The solvent is evaporated and the residue is dissolved in mobile phase (acetonitrile–water, 40:60, v/v; acidified at pH 3.0 with phosphoric acid) and separated by liquid chromatography using fluorescence detection. The limit of detection was 0.005 ng/ml. The average recovery rate and the average RSD of recovery in the spiking level range 0.01–0.5 ng/ml were 95.5% and about 5%, respective…
New method for determination of ochratoxin A in beer using zinc acetate and solid-phase extraction silica cartridges
2006
Abstract A new method for the determination of ochratoxin A (OTA) in beer has been developed. The new method has been compared with a reference method currently accepted as AOAC official first action. The limits of detection and quantification of the proposed method were 0.0008 and 0.0025 ng/ml, respectively, while they were 0.0025 and 0.0075 ng/ml, respectively, in the AOAC method used as reference. The recovery levels in the 0.025–0.40 ng OTA/ml spiking range for the proposed and the reference methods were 80.6–87.6% and 78.2–83.8%, respectively. The relative standard deviations of recoveries were 2.6–7.5% for the proposed method and 0.7–6.1% for the reference method. Passing and Bablok r…
Hydrophobicity of ionisable compounds studied by countercurrent chromatography
2011
Countercurrent chromatography (CCC) is a liquid chromatography technique in which the stationary phase is also a liquid. The main chemical process involved in solute separation is partitioning between the two immiscible liquid phases: the mobile phase and the support-free liquid stationary phase. The octanol-water partition coefficients (P(o/w)) is the accepted parameter measuring the hydrophobicity of molecules. It is considered to estimate active principle partitioning over a biomembrane. It was related to the substance biological activity. CCC is able to work with an octanol stationary phase and an aqueous mobile phase. In this configuration, CCC is a useful and easy alternative to measu…
Sample pretreatment techniques for oligopeptide analysis from natural sources
2008
The analysis of oligopeptides in samples of food, tissues, and body fluids attracts considerable attention. The complexity of such samples requires efficient sample preparation (i.e., concentration and cleanup) procedures to remove interfering endogenous compounds and inorganic or organic salts. The methods of sample pretreatment that enable effective and selective isolation and/or preconcentration of oligopeptides from complex sample matrices have been reviewed. In each case, examples of application were presented and discussed, taking into account selectivity, enrichment, method automation, cleanup, and environmental aspects of the developed methods.
Impact of body weight, low energy diet and gastric bypass on drug bioavailability, cardiovascular risk factors and metabolic biomarkers: protocol for…
2018
IntroductionRoux-en-Y gastric bypass (GBP) is associated with changes in cardiometabolic risk factors and bioavailability of drugs, but whether these changes are induced by calorie restriction, the weight loss or surgery per se, remains uncertain. The COCKTAIL study was designed to disentangle the short-term (6 weeks) metabolic and pharmacokinetic effects of GBP and a very low energy diet (VLED) by inducing a similar weight loss in the two groups.Methods and analysisThis open, non-randomised, three-armed, single-centre study is performed at a tertiary care centre in Norway. It aims to compare the short-term (6 weeks) and long-term (2 years) effects of GBP and VLED on, first, bioavailability…
Intracellular signalling via the AKT axis and downstream effectors is active and prognostically significant in cancer of unknown primary (CUP): a stu…
2012
Background: Hypothesising that cancer of unknown primary (CUP) may harbour unique characteristics, we present a translational study of the immunohistochemical expression and clinical correlation of key PTEN/AKT pathway molecules. Patients and methods: We collected 100 paraffin-embedded CUP tissue blocks. We studied using tissue microarrays the expression of PTEN, phospho-AKT, Cyclin D1, p21, phospho-RPS6. From the percentage of staining tumour cells and the literature, we selected cut-offs to classify the expression of each biomolecule. We correlated IHC expression with clinical data. Results: PTEN, pAKT, and pRPS6 showed frequent expression. At univariate analysis, high IHC expression of p…
OCTN2-Mediated Carnitine Uptake in a Newly Discovered Human Proximal Tubule Cell Line (Caki-1)
2006
The proximal tubular reabsorption of carnitine in the human kidney is significant because more than 95% of the carnitine filtered in the kidney is reabsorbed by the proximal tubules therefore maintaining the homeostatic balance of carnitine in the body. Objectives of this study include the characterization of OCTN2 function in the Caki-1 cell line and the potential interactions of carnitine uptake with renally secreted drugs, including drugs of quaternary ammonium structure. Caki-1 cells were additionally characterized to be of proximal tubule nature, and an apical membrane expression pattern of OCTN2 in Caki-1 cells was discovered. Uptake studies with radiolabeled L-carnitine in Caki-1 cel…
Influence of Instrument Size on the Accuracy of Different Apex Locators: An In Vitro Study
2008
The aim of this in vitro investigation was to determine the accuracy of 4 different electronic apex locators (EALs) with 3 different instrument sizes. For this study 146 roots were embedded in an agar solution. Electronic measurements were made to the physiologic foramen (apical constriction) with the Elements Apex Locator, Justy II, Raypex 5, and ProPex II and K-type files sizes 08, 10, and 15. Statistical significances were calculated with the sign test (P < .001). Exact measurements to the physiologic foramen were made with the Elements Apex Locator, 36.99%, 39.04%, and 44.93%; Justy II, 38.62%, 32.41%, and 43.41%; Raypex 5, 42.76%, 39.31%, and 39.06%; and ProPex II, 38.62%, 43.45%, and …