The Bureau International des Poids et Mesures (BIPM) is developing, with the support of national metrology institutes, an extension to the existing international reference system for international ...comparisons in radionuclide metrology. The extended system is addressing pure α-, pure β-emitting and some electron capture-decaying radionuclides. The new system is based on a custom-built liquid scintillation counter and the triple-to-double coincidence ratio (TDCR) technique. Particular emphasis was placed on long-term stability and excellent reproducibility in sample preparation. The analytical method is based on a special approach that uses the TDCR value as a parameter to compensate for fluctuations caused by changes in detection efficiency or photomultiplier asymmetries that cannot be excluded when considering very long periods. Measures for quality assurance were established. They are based on periodic controls of unquenched toluene-based liquid scintillation sources with
3
H and
14
C. In this way, the reproducibility of the system results is demonstrated for a test period of about twenty months.
The activity concentration of a
177
Lu solution was measured by the Laboratory of Radioactivity Standards in the Radioisotope Centre POLATOM. The solution was measured by means of 4
πβ
(LS)-
γ
...coincidence and anticoincidence counting. Both methods gave consistent results of the activity concentration, a relative standard uncertainty of 0.24% was obtained, which is much smaller than the uncertainty of previous measurement performed within the scope of the international comparison CCRI(II)-K2.Lu-177 in 2009.
To establish a more precise calibration factor of a 4π ionization chamber for this isotope, the obtained result of activity concentration was used.
Registration of the effects of interaction of the radiation emitted after radioactive decay enables determination of activity of a given material expressed in becquerels (Bq). Measurements in a frame ...of international comparisons of 14C activity using the triple-to-double coincidence ratio (TDCR) method and of 177Lu activity using the 4p(LS)-g coincidence and anticoincidence method, where the liquid scintillation technique (LSC) was used, were described. Specificity of short-lived radionuclides activity determination was discussed.
The Bureau International des Poids et Mesures (BIPM) is developing, with the support of national metrology institutes, an extension to the existing international reference system for international ...comparisons in radionuclide metrology. The extended system is addressing pure alpha-, pure beta-emitting and some electron capture-decaying radionuclides. The new system is based on a custom-built liquid scintillation counter and the triple-to-double coincidence ratio (TDCR) technique. Particular emphasis was placed on long-term stability and excellent reproducibility in sample preparation. The analytical method is based on a special approach that uses the TDCR value as a parameter to compensate for fluctuations caused by changes in detection efficiency or photomultiplier asymmetries that cannot be excluded when considering very long periods. Measures for quality assurance were established. They are based on periodic controls of unquenched toluene-based liquid scintillation sources with .sup.3H and .sup.14C. In this way, the reproducibility of the system results is demonstrated for a test period of about twenty months.
The activity concentration of a .sup.177Lu solution was measured by the Laboratory of Radioactivity Standards in the Radioisotope Centre POLATOM. The solution was measured by means of ...4pibeta(LS)-gamma coincidence and anticoincidence counting. Both methods gave consistent results of the activity concentration, a relative standard uncertainty of 0.24% was obtained, which is much smaller than the uncertainty of previous measurement performed within the scope of the international comparison CCRI(II)-K2.Lu-177 in 2009. To establish a more precise calibration factor of a 4pi ionization chamber for this isotope, the obtained result of activity concentration was used.
During the investigations, functionalization of graphene oxide synthesized using modified Hummers' method and its reduced form was performed. Mixtures of graphene oxide and reduced graphene oxide ...with pimelic acid and calcium hydroxide were prepared for functionalization. During the reaction, the molecules of pimelic acid were attached to the surface of graphene sheets. By forming links between the carboxylic groups of pimelic acid and graphene oxide, the durable connection was achieved. The functionalized graphene oxide and the reduced graphene oxide were used as additives in isotactic polypropylene crystallization. The influence of additives on crystallisation in non-isothermal conditions was examined using polarized optical microscopy and differential scanning calorimetry. The effect of the additives on the polypropylene structure was analysed using wide-angle X-ray scattering. For both functionalized compounds, the nucleating ability towards beta-form of polypropylene was detected. Both additives showed the increase in the nucleation rate and promotion of growth of the beta-form crystals. Nucleation efficiency similar to other nucleating agents used in the crystallization of the beta-form of polypropylene was revealed.
Pimelic acid and calcium hydroxide were used to attach calcium pimelate to the surface of graphene oxide. The additive was mixed with isotactic polypropylene granulate. Neat polypropylene and ...polypropylene with functionalized graphene oxide was extruded into fibers under laboratory conditions. The gravity spun fibers containing different concentration of the additive and the fibers taken at various velocities were obtained. Morphology and elemental composition of functionalized graphene oxide were studied by means of scanning electron microscopy and energy dispersive X-ray spectroscopy. The structure of fibers was examined by means of differential scanning calorimetry and wide-angle X-ray scattering. The ability of calcium pimelate supported on the surface of the graphene oxide to nucleate the β-form of polypropylene was revealed. A considerable amount of the β-form crystals was obtained in the gravity spun fibers. In the fibers taken at moderate and higher velocities the β-form disappeared. The structure of the fibers extruded with the additive was similar to the structure of the fibers extruded from neat polypropylene. At moderate velocities, the content of mesophase in the structure was high. At higher velocities, the crystalline structure built only from α-form crystals was obtained. The paper presents a discussion of the changes observed in the fiber structure in connection with polypropylene nucleation.
Biodegradation of sheep wool geotextiles Broda, Jan; Przybyło, Stanisława; Kobiela-Mendrek, Katarzyna ...
International biodeterioration & biodegradation,
11/2016, Letnik:
115
Journal Article
Recenzirano
Innovative geotextiles designed for erosion control and made from meandrically arranged coarse ropes were produced. The ropes filled with sheep wool and wrapped with woollen nonwoven were buried in ...the local ground. During one year of soil exposure the progress of wool biodegradation was observed. During investigations the morphology and chemical composition of wool and change of basic mechanical parameters of single fibres and woollen nonwoven were analysed. In the first months of the burial the deterioration of mechanical parameters, destruction of scales on the fibres surface and cleavage of disulphide bonds of keratin was observed. In the following months, further reduction of mechanical parameters, successive destruction of cuticle and deeper layers of the fibres followed by fibres defibrillation and the disruption of peptide bonds occurred. Rapid biodegradation leading to defibrillation occurred in the mechanically damaged fibres. It was concluded that, thanks to slow biodegradation, the ropes maintain their protective potential for one vegetation session, what is sufficient for the development of the protective vegetation on the slope.
•The progress of biodegradation of woollen geotextiles designed for erosion control during one year was analysed.•The progressive degradation of fibres from the cuticle to the cortex was revealed.•The potential of woollen geotextiles to maintain their protective potential for one vegetation session was proved.
The geotextiles produced from meandrically arranged Kemafil ropes were prepared. The ropes were produced from textile waste materials: woollen nonwoven and nonwoven from the blend of recycled fibres. ...The ropes were arranged into segments which were used for the protection of the bank of the deep drainage ditch and reinforcement of shallow roadside ditch in the clay ground. The geotextiles were installed in the ground and their behaviour during one vegetation season was observed. It was stated that during heavy rains the meandrically arranged ropes form a system of micro-dams which slow down the stream of water flowing down on the surface of the ditch bank as well as the stream flowing along the ditch. The geotextiles installed on the ditch banks eliminate the formation of erosive channels and protect the banks against sliding. The geotextiles absorb water what ensures retention of water flowing along the ditch. Due to enhanced soil and water holding capacity geotextiles protect grass seeds from being washed out and facilitate the development of protective vegetation. Materials used for the production of the ropes reveal sufficient resistance to biological degradation. Slow biodegradation of the materials enable keeping the protective potential of geotextiles for at least one vegetation season.
Textile waste was used for production of thick ropes designed for the protection of slopes against sliding and erosion. For the production of ropes, scraps of insulating materials produced from poor ...quality wool and scraps of nonwoven manufactured from blend of recycled fibres were applied. The ropes were installed on the slope in a disused gravel pit. Stabilisation of the slope and behaviour of the materials used were analysed during two vegetation seasons. Investigations confirmed the usefulness of the technology for the protection of steep slopes.
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