A fitting procedure for palaeodose from old sandstone using IRSL

In the dating studies of old samples using the Infrared Stimulated Luminescence (IRSL), the validity of the curve-fitting employed is of critical importance. So, in this study, a new fitting procedure was suggested for obtaining the age of the old geological sample. IRSL technique was applied using multiple-aliquot procedure to feldspar isolated from sample. The paleodose results obtained, using linear and polynomial fitting, were (67.98±2) Gy, (30.49±2) Gy and 322.03 Gy from the suggested fitting procedure. After application of this procedure the age was found to be 551.4 ka. This work was supported by Karaelmas University under the project numbered 98-101-009-01.     

Surfactant removal and silica condensation during the photochemical calcination of thin film silica mesophases

The evolution of photochemical surfactant removal and silica condensation from organically templated thin film silica nanocomposites with mesoscopic ordering has been probed using a combined application of Fourier transform infrared (FT-IR) spectroscopy and single wavelength ellipsometry. Thin films of silica nanocomposites were prepared by a previously reported evaporation-induced self-assembly process. Specifically, oxidized silicon and gold substrates were withdrawn at 25 mm/min from a subcritical micelle concentration solution containing an ethylene oxide surfactant as a structure-directing agent and tetraethyl orthosilicate as a silica precursor. Real-time grazing incidence difference FT-IR spectra of the nanocomposite films on gold taken during exposure to short-wavelength ultraviolet light (184-257 nm) show that surfactant removal and silica condensation occur gradually and concomitantly. Surfactant removal and silica reconstructions were found to be nearly complete after 90 min of exposure. Further, a transient feature was observed in the FT-IR spectra around 1713 cm(-1) during the UV exposure process and was assigned to a carbonyl (C=O) stretching mode absorption, reflecting the transient formation of a partially oxidized surfactant intermediate. From these data we propose a stepwise model for surfactant removal from the nanocomposite films. Ellipsometrically determined index of refraction values collected as a function of UV exposure are also shown to support such a stepwise mechanism of surfactant removal from the ordered nanocomposite silica thin film mesophases studied here.     

Analysis of anabolic steroids by partial filling micellar electrokinetic capillary chromatography and electrospray mass spectrometry

A partial filling micellar electrokinetic capillary chromatography (PF-MEKC) separation of six anabolic androgenic steroids (androstenedione, metandienone, fluoxymesterone, methyltestosterone, 17-epimetandienone and testosterone) is introduced. The method utilises a mixed micellar solution consisting of sodium dodecyl sulphate (SDS) and sodium taurocholate. The analytes are detected with a photodiode array detector at 247 nm wavelength. Methyltestosterone is used as internal standard. The detection limits were 39 microg/L for androstenedione, 40 microg/L for testosterone, 45 microg/L for fluoxymesterone, 45-90 microg/L for 17-epimetandienone, 59 microg/L for methyltestosterone and 90 microg/L for metandienone. Linear correlation between concentration (0.1-5.0 mg/L) and detector response was obtained with r2 of 0.994 for fluoxymesterone, 0.998 for 17-epimetandienone and 0.999 for androstenedione, metandienone and testosterone. In addition, ionisation of the investigated compounds in electrospray mass spectrometry (ESI-MS) was studied in positive ion mode. The most intense signal (100%) was the protonated molecular ion [M + H]+, except for 17-epimetandienone, which gave its strongest signal at m/z corresponding to [M - H2O + H]+. Finally, separation and identification of fluoxymesterone, androstenedione and testosterone by PF-MEKC-ESI-MS is described. This is the first use of PF-MEKC and PF-MEKC-ESI-MS assays for anabolic androgenic steroids.     

On-line process monitoring of water-soluble ions in pulp and paper machine waters by capillary electrophoresis

In this study, capillary electrophoresis (CE) was used for separation of inorganic and organic ions from waters of paper and paperboard machines at mills. The instrument was constructed for on-line measurements by building a batch-type sample feeding unit. Chloride, thiosulphate, sulphate, oxalate, sulphite, hydrogen sulphide, formate, carbonate, phosphate and acetate in the process water samples were separated using an ion-specific separation system in CE with dicarboxylic acid buffer (pH 8.2), with pyridinium-2,3-dicarboxylic acid modified with commercial NICE-Pak OFM-OH solution (pH 12.0) or with a cetyltrimethylammonium bromide solution modified with chromate (pH 10.6). In addition, Analis CEofix Anions 8 electrolyte solution was tested in on-line studies at mills. It allowed 5 min separation time for the anions. Aluminium was determined at pH 3.6 in 10 min by using a laboratory-made imidazole buffer modified with 18-crown 6-ether. The developed CE systems were used to monitor the concentrations of sulphur species in dithionite degradation, to estimate corrosion degree in the water tanks, to monitor formaldehyde as the biocide chemical in wire washing and, in general, to observe process disturbances resulting from chemical feedings and their sites. The CE combination was on-line coupled to eight different process machines for continuous monitoring of concentrations for periods between two weeks and one month at paper and pulp mills in Finland.     

Applicability of continuous-flow fast atom bombardment liquid chromatography-mass spectrometry in bioanalysis. Dextromethorphan in plasma

Continuous-flow fast atom bombardment (CF-FAB) is an interface for combined liquid chromatography-mass spectrometry using FAB as the ionization method. The applicability of CF-FAB for quantitative bioanalysis was studied for a model compound, dextromethorphan, in plasma samples using conventional high-performance liquid chromatography. The flow-rate reduction was achieved either by splitting or by the phase-system switching approach. The features of both systems are discussed.     

Bannai–Ito algebras and the universal R-matrix of $$\pmb {\mathfrak {osp}}(1|2)$$osp(1|2)

Letters in Mathematical Physics - The Bannai–Ito algebra BI(n) is viewed as the centralizer of the action of $$\mathfrak {osp}(1|2)$$ in the n-fold tensor product of the universal algebra of...     

The effect of introduction of carbon nanotubes on the physicomechanical properties of polyvinylacetate

The physicomechanical properties of polyvinylacetate (PVA) with small, no more than 2 wt.%, additions of carbon nanotubes (CNTs) are investigated. Data on the influence of CNT concentration on the differential scanning calorimetry thermograms, thermal destruction, electrical resistance, water vapor sorption, as well as indices of the mechanical properties of PVA/CNT (yield stress, strength, elastic modulus, ultimate elongation, and short-term creep) are reported. A variant of calculation of the elastic constants of the nanocomposite is considered with account of the effect of nanotube agglomeration.     

CHASE, a charge-assisted sequencing algorithm for automated homology-based protein identifications with matrix-assisted laser desorption/ionization time-of-flight post-source decay fragmentation data

We describe CHASE, a novel algorithm for automated de novo sequencing based on the mass spectrometric (MS) fragmentation analysis of tryptic peptides. This algorithm is used for protein identification from sequence similarity criteria and consists of four steps: (1) derivatization of tryptic peptides at the N-terminus with a negatively charged reagent; (2) post-source decay (PSD) fragmentation analysis of peptides; (3) interpretation of the mass peaks with the CHASE algorithm and reconstruction of the amino acid sequence; (4) transfer of these data to software for protein identifications based on sequence homology (Basic Local Alignment Search Tool, BLAST). This procedure deduced the correct amino acid sequence of tryptic peptide samples and also was able to deduce the correct sequence from difficult mass patterns and identify the amino acid sequence. This allows complete automation of the process starting from MS fragmentation of complex peptide mixtures at low concentration (e.g. from silver-stained gel bands) to identification of the protein. We also show that if PSD data are collected in a single spectrum (instead of the segmented mode offered by conventional matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) instrumentation), the complete workflow from MS-PSD data acquisition to similarity-based identification can be completely automated. This strategy may be applied to proteomic studies for protein identification based on automated de novo sequencing instead of MS or tandem MS patterns. We describe the Charge Assisted Sequencing Engine (CHASE) algorithm, the working protocol, the performance of the algorithm on spectra from MALDI-TOFMS and the data comparison between a TOF and a TOF-TOF instrument.