Routine individual monitoring of aircraft crew exposure: Czech experience and results since 1998

ICRP Publication 60 recommended that the radiation exposure due to the cosmic component at high altitudes be considered when appropriate as part of occupational exposure to the radiation. The recommendation was incorporated to the Czech regulation in 1997, and the studies on how to perform individual dosimetry of Czech companies aircraft crew started immediately. The individual monitoring values were calculated using the Transport code CARI. The results obtained since the beginning have been recalculated, now with the version 6. The information on the flight schedules and the participation of aircraft crew in the flight were received from the air company. Routine individual dosimetry had started in 1998. Main results for the period 1998-2003 are as follows: both relative frequencies, as well as, average annual effective doses vary with the company and with the year, without any evident general tendency; the average annual values of E were between 1.5 and 2 mSv; and collective effective dose increased regularly, from approximately 1.5 manSv to >2.2 manSv. More detailed analysis is presented, including the verification of the procedure by a series of onboard experimental measurements.     

Adhesion and growth of vascular smooth muscle cells in cultures on bioactive RGD peptide-carrying polylactides

The surface of poly(l-lactide) (PLLA) films deposited on glass coverslips was modified with poly(dl-lactide) (PDLLA), or 1:4 mixtures of PDLLA and PDLLA-b-PEO block copolymers, in which either none, 5% or 20% of the copolymer molecules carried a synthetic extracellular matrix-derived ligand for integrin adhesion receptors, the GRGDSG oligopeptide, attached to the end of the PEO chain. The materials, perspective for vascular tissue engineering, were seeded with rat aortic smooth muscle cells (11,000 cells/cm²) and the adhesion, spreading, DNA synthesis and proliferation of these cells was followed on inert and bioactive surfaces. In 24-h-old cultures in serum-supplemented media, the number of cells adhering to the PDLLA-b-PEO copolymer was almost eight times lower than that on the control PDLLA surface. On the surfaces containing 5% and 20% GRGDSG-PEO-b-PDLLA copolymer, the number of cells increased 6- and 3-fold respectively, compared to the PDLLA-b-PEO copolymer alone. On PDLLA-b-PEO copolymer alone, the cells were typically round and non-spread, whereas on GRGDSG-modified surfaces the cell spreading areas approached those found on PDLLA, reaching values of 991 μm² and 611 μm² for 5% and 20% GRGDSG respectively, compared to 958 μm² for PDLLA. The cells on GRGDSG-grafted copolymers were able to form vinculin-containing focal adhesion plaques, to synthesize DNA and even proliferate in a serum-free medium, which indicates specific binding to the GRGDSG sequences through their adhesion receptors.     

Room-temperature bonding for plastic high-pressure microfluidic chips

A generic method for the rapid, reproducible, and robust bonding of microfluidic chips fabricated from plastics has been developed and optimized. One of the bonding surfaces is exposed to solvent vapor prior to bringing the mating parts into contact and applying a load. Nanoindentation measurements performed by atomic force microscopy show that a reversible material softening occurs upon exposure to solvent vapor. Subsequent exposure of the bonded chip to UV light then strengthens the bond between mating parts and increases the burst pressure by 50% due to partial cross-linking and chain scission reactions as measured by size exclusion chromatography-multiangle light scattering (SEC-MALS). Performing all steps of this procedure at room temperature eliminates channel distortion observed during thermal bonding and affords channels with highly uniform cross-sectional dimensions. Our technique enables chips resistant to pressures as high as 34.6 MPa.     

Application of image analysis method to detection and counting of glass fibers from filter samples

Man-made vitreous fibers (MMVFs) are noncrystalline substances made of glass, rock or slag and are widely used as thermal or acoustic insulation materials. There is continued concern about their potential health impacts and thus, their dosimetry and behavior in the environment still require study using filters to collect fiber samples. After deposition or exposure measurements of MMVFs it is often necessary to analyze the filters with deposited fibers. This task is tedious, time-consuming, and requires skill. Therefore, many researchers have tried to simplify or automatize fiber detection and quantification. This article describes features of our in-house software, which automatically detects and counts fibers in images of filter samples. The image analysis is based on the use of a histogram equalization and an adaptive radial convolution filter that enhances fiber contrast and thus, improves the fiber identification. The accuracy of the software analysis was verified by comparison with manual counting using ordinary phase-contrast microscopy method. The correlation between the methods was very high (coefficient of determination was 0.977). However, there were some discrepancies caused by false identifications, which led to implementation of manual corrective functions.

Copyright © 2016 American Association for Aerosol Research     

Impact Of Long-Term Storage On The Instrumental Textural Properties Of Frozen Common Carp (Cyprinus Carpio,L.) Flesh

The aim of the work was to measure and confirm changes in the qualitative properties of frozen carp flesh (Cyprinus carpio L.) during 84 days of storage at -20°C, using instrumental texture profile analysis focused on hardness, cohesiveness, and springiness. Hardness in fresh fish was 2.908 N, in fish stored 28 days 1.238 N, after 56 days 0.505 N, and after 84 days 0.491 N. Cohesiveness (dimensionless unit) in fresh fish was 0.838, after 28 days 0.740, after 56 days 0.720, and after 84 days 0.712. Springiness (dimensionless unit) in fresh fish was 0.682, after 28 days 0.625, after 56 days 0.577, and at 84 days of storage 0.534. The texture profile analysis effect was determined by several regression and linear models. It is possible to calculate a certain time period in which changes develop up to the level of 50% of deterioration—in hardness 17.5 days and in cohesiveness 12.9 days, as this was proven to a defined significance level (P > 0.01). Only changes in springiness showed a linear regression in the level of 0.002 (rounded) for each day. Studies showed that the intensity of the most important changes in instrumental textural properties occurred during the initial 56 days after freezing and after up to 84 days of storage the changes continued at a lesser rate.     

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.     

Suspensions Plasma Spraying of Ceramics with Hybrid Water-Stabilized Plasma Technology

Technology of water-stabilized plasma torch was recently substantially updated through introduction of a so-called hybrid concept that combines benefits of water stabilization and gas stabilization principles. The high-enthalpy plasma provided by the WSP-H (“hybrid”) torch may be used for thermal spraying of powders as well as liquid feedstocks with high feed rates. In this study, results from three selected experiments with suspension plasma spraying with WSP-H technology are presented. Possibility of deposition of coatings with controlled microstructures was demonstrated for three different ceramics (YSZ—yttria-stabilized zirconia, YAG—yttrium aluminum garnet and Al₂O₃) introduced into ethanol-based suspensions. Shadowgraphy was used for optimization of suspension injection and visualization of the liquid fragmentation in the plasma jet. Coatings were deposited onto substrates attached to the rotating carousel with integrated temperature monitoring and air cooling, which provided an excellent reproducibility of the deposition process. Deposition of columnar-like YSZ and dense YAG and Al₂O₃ coatings was successfully achieved. Deposition efficiency reached more than 50%, as evaluated according to EN ISO 17 836 standard.     

Controlling Microstructure of Yttria-Stabilized Zirconia Prepared from Suspensions and Solutions by Plasma Spraying with High Feed Rates

Introduction of suspension and solution plasma spraying led to a breakthrough in the deposition of yttria-stabilized zirconia (YSZ) coatings and enabled preparation of new types of layers. However, their deposition with high feed rates needed, for example, for the deposition of thermal barrier coatings (TBCs) on large-scale components, is still challenging. In this study, possibility of high-throughput plasma spraying of YSZ coatings is demonstrated for the latest generation of high-enthalpy hybrid water-stabilized plasma (WSP-H) torch technology. The results show that microstructure of the coatings prepared by WSP-H may be tailored for specific applications by the choice of deposition conditions, in particular formulation of the liquid feedstock. Porous and columnar coatings with low thermal conductivity (0.5-0.6 W/mK) were prepared from commercial ethanol-based suspension. Dense vertically cracked coatings with higher thermal conductivity but also higher internal cohesion were deposited from suspension containing ethanol/water mixture and coarser YSZ particles. Spraying of solution formulated from diluted zirconium acetate and yttrium nitrate hexahydrate led also to the successful deposition of YSZ coating combining regions of porous and denser microstructure and providing both low thermal conductivity and improved cohesion of the coating. Enthalpy content, liquid-plasma interaction and coating buildup mechanisms are also discussed.