Doses and LET spectra in the beam of 12C with energy 500 MeV amu-1

This paper describes the results of experimental studies performed at the Joint Institute for Nuclear Research (JINR) in a (12)C ion beam with the primary nominal energy 500 MeV amu(-1). Data measured by means of a diamond detector and a spectrometer of linear energy transfer (LET) based on chemically etched track detectors are presented, analysed and discussed. LET spectra are also calculated by program SRIM.     

Tandem mass spectrometry for the direct assay of lysosomal enzymes in dried blood spots: application to screening newborns for mucopolysaccharidosis VI (Maroteaux-Lamy syndrome)

We report a new assay of N-acetylgalactosamine-4-sulfatase (aryl sulfatase B) activity in dried blood spots (DBS) for the early detection of mucopolysaccharidosis VI (Maroteaux-Lamy syndrome) in newborn screening. The assay uses a synthetic substrate consisting of N-acetylgalactosamine-4-sulfate moiety glycosidically linked to a hydrophobic residue and furnished with a tert-butyloxycarbamido group as a marker for specific mass spectrometric fragmentation. Incubation with aryl sulfatase B present in DBS converts the substrate to a desulfated product which is detected by electrospray tandem mass spectrometry and quantified using a homologous internal standard. Assay and workup procedures were optimized to be compatible with the work flow in newborn screening laboratories. Analysis of DBS from human newborns showed clear distinction of aryl sulfatase B activity from 89 healthy individuals where it ranged between 1.4 and 16.9 μmol/(h L of blood), with an average activity of 7.4 μmol/(h L of blood), and an MPS-VI patient that had an activity of 0.12 μmol/(h L of blood). Results are also reported for the aryl sulfatase B assay in DBS from groups of normal felines and felines affected with MPS-VI.     

Measurement of Specific Fracture Energy and Surface Tension of Brittle Materials in Powder Form

Studies of the influence of specimen geometry and size–effect on the K _R –curves and the related fracture parameters were carried out by the authors (Kumar and Barai 2008b). The present paper is a supplementary contribution and reports interesting results related to the effect of the loading condition and size–effect studies on the K _R –curves associated with the cohesive stress distribution for complete fracture process, the double–K fracture parameters, the CTOD–curves and the process zone length using two different loading conditions (i.e., three–point bending test and four–point bending test). The laboratory size specimen with initial–notch length/depth ratios 0.3 and 0.5 are considered in the work. The load–crack opening displacement curves for these loading conditions are obtained using well known version of fictitious crack model.     

Acidic leaching both of zinc and iron from basic oxygen furnace sludge

During the steel production in the basic oxygen furnace (BOF), approximately 7-15 kg of dust per tonne of produced steel is generated. This dust contains approximately 1.4-3.2% Zn and 54-70% Fe. Regarding the zinc content, the BOF dust is considered to be highly problematic, and therefore new technological processes for recycling dusts and sludge from metallurgical production are still searched for. In this study the hydrometallurgical processing of BOF sludge in the sulphuric acid solutions under atmospheric pressure and temperatures up to 100 °C is investigated on laboratory scale. The influence of sulphuric acid concentration, temperature, time and liquid to solid ratio (L:S) on the leaching process was studied. The main aim of this study was to determine optimal conditions when the maximum amount of zinc passes into the solution whilst iron remains in a solid residue.     

Polar polymeric stationary phases for normal-phase HPLC based on monodisperse macroporous poly(2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate) beads

The effect of variables such as shape template size, porogen composition and percentage, content of cross-linking monomer, and polymerization temperature on the properties of uniformly sized 3-microm porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads prepared by the staged templated suspension polymerization technique has been studied. The porous properties of the beads including surface morphology, pore size distribution, and specific surface area have been optimized to obtain highly efficient stationary phases for normal-phase HPLC. A column packed with diol stationary phase obtained by hydrolysis of poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads affords an efficiency of 67,000 plates/m for toluene using THF as the mobile phase. The retention properties and selectivity of the diol beads are easily modulated by changes in the composition of the mobile phase. The performance of these beads is demonstrated with the separations of a variety of polar compounds including positional isomers, aniline derivatives, and basic tricyclic antidepressant drugs.     

Absolute quantification of specific proteins in complex mixtures using visible isotope-coded affinity tags

The identification of proteins in complex mixtures is most useful when quantitative information is also obtained. We describe a new type of protein tagging reagent called the visible isotope-coded affinity tag (VICAT) which allows the absolute amount of a target protein or proteins to be quantified in a complex biological sample such as a eukaryotic cell lysate. VICAT reagents tag thiol groups of cysteines or thioacetylated amino groups and introduce into the tryptic peptide a biotin affinity handle, a visible moiety for tracking the chromatographic location of the target peptide by a method other than mass spectrometry, a photocleavable linker for removing a portion of the tag, and an isotope tag for distinguishing sample and internal standard peptides. We demonstrate the use of VICAT reagents together with isoelectric focusing of peptides on an immobilized gel strip followed by combined micro-liquid chromatography/electrospray ionization mass spectrometry operating in selected reaction monitoring mode to determine the absolute abundance of a specific protein, human group V phospholipase A(2), in eukaryotic cell lysates. It is found that human lung macrophages contain 66 fmol of this protein per 100 microg of cell protein. Western blot analysis of human group V phospholipase A(2) in macrophages gave inconclusive data. VICAT reagents should be useful for numerous applications including the analysis of candidate disease markers in complex mixtures such as serum.     

Enzymatic microreactor-on-a-chip: protein mapping using trypsin immobilized on porous polymer monoliths molded in channels of microfluidic devices

Enzymatic microreactors have been prepared in capillaries and on microfluidic chips by immobilizing trypsin on porous polymer monoliths consisting of 2-vinyl-4,4-dimethylazlactone, ethylene dimethacrylate, and acrylamide or 2-hydroxyethyl methacrylate. The azlactone functionalities react readily with amine and thiol groups of the enzyme to form stable covalent bonds. The optimized porous properties of the monoliths lead to very low back pressures enabling the use of simple mechanical pumping to carry out both the immobilization of the enzyme from its solution and the subsequent analyses of substrate solutions. The Michealis-Menten kinetic characteristics of the reactors were probed using a low molecular weight substrate: N-alpha-benzoyl-L-arginine ethyl ester. The effects of immobilization variables such as the concentration of trypsin in solution and percentage of azlactone functionalities in the monolith, as well as the effect of reaction time on the enzymatic activity, and of process variables such as substrate flow velocity and residence time in the reactor, were studied in detail. The proteolytic activity of the enzymatic microreactor on chip was demonstrated at different flow rates with the cleavage of fluorescently labeled casein used as a substrate. The excellent performance of the monolithic microreactor was also demonstrated with the digestion of myoglobin at the fast flow rate of 0.5 microL/min, which affords a residence time of only 11.7 s. The digest was then characterized using MALDI-TOF MS, and 102 out of 153 possible peptide fragments were identified giving a sequence coverage of 67%.     

Development of a realistic human airway model

Numerous models of human lungs with various levels of idealization have been reported in the literature; consequently, results acquired using these models are difficult to compare to in vivo measurements. We have developed a set of model components based on realistic geometries, which permits the analysis of the effects of subsequent model simplification. A realistic digital upper airway geometry except for the lack of an oral cavity has been created which proved suitable both for computational fluid dynamics (CFD) simulations and for the fabrication of physical models. Subsequently, an oral cavity was added to the tracheobronchial geometry. The airway geometry including the oral cavity was adjusted to enable fabrication of a semi-realistic model. Five physical models were created based on these three digital geometries. Two optically transparent models, one with and one without the oral cavity, were constructed for flow velocity measurements, two realistic segmented models, one with and one without the oral cavity, were constructed for particle deposition measurements, and a semi-realistic model with glass cylindrical airways was developed for optical measurements of flow velocity and in situ particle size measurements. One-dimensional phase doppler anemometry measurements were made and compared to the CFD calculations for this model and good agreement was obtained.     

Translation of segment scale stiffening into macroscale reinforcement in polymer nanocomposites

Structuring of polymer nanocomposites (PNCs) with an aid of relatively weak external magnetic fields has been studied as a method for control of the nano- and microstructure. Magnetic nanoparticles (NPs) were assembled into high aspect ratio one-dimensional strings and unidirectionally oriented with the magnetic field (B = 0–50 mT) within the photopolymer matrix. The effect of the anisotropic MNPs assemblies on the mechanical properties was studied over a wide temperature range for the first time. The impact of various reinforcing mechanisms was distinguished with respect to the position of the glass transition temperature (T_g). The reinforcing effect exhibits temperature dependency with a maximum ~65°C above the glass transition and only negligible effect below the T_g. In addition, significant directional anisotropy of stiffness was observed. Composite micromechanics was applied to interpret the orientation and size-dependent reinforcement of PNCs, and temperature-dependent stiffness of the polymer-MNP structures was quantified. The presence of polymer chains with altered dynamics surrounding the MNPs inside the anisotropic assemblies was proposed to be an essential nanoscale mechanism mediating the stress transfer and contributing to mechanical robustness of the hybrid structures and PNCs. POLYM. ENG. SCI., 60:587–596, 2020. © 2019 Society of Plastics Engineers