In this study, mercerisation of native cellulose I was achieved in an aqueous sodium hydroxide solution at a concentration of only 1 wt% NaOH by processing at temperatures below 0 degree C. This ...represents a tenfold reduction in the use of NaOH to accomplish this very common transformation. The cellulose sample was a form of hydrolysed cotton with a high crystallinity. The samples were mixed with aqueous sodium hydroxide at various concentrations and stored at -17 degree C. The samples were then defrosted, neutralised and dried before being analysed by Fourier-transform infrared spectroscopy, wide-angle X-ray diffraction and field-emission scanning electron microscopy. In the route described here, transformation from cellulose I to cellulose II was possible without greatly affecting the crystallinity or the microstructure of the samples.
Negative size effects are commonly reported for advanced composite materials where the strength of the material decreases with increasing volume of the test specimen. In this work, the effect of ...increasing specimen volume on the mechanical properties of all-cellulose composites is examined by varying the laminate thickness. A positive size effect is observed in all-cellulose composite laminates as demonstrated by a 32.8% increase in tensile strength as the laminate thickness is increased by 7 times. The damage evolution in all-cellulose composite laminates was examined as a function of the tensile strain. Enhanced damage tolerance concomitant with increasing specimen volume is associated with damage accumulation due to transverse cracking and strain delocalisation. A transition from low-strain failure to tough and high-strain failure is observed as the laminate thickness is increased. Simultaneously, scale effects lead to an increase in the void content and cellulose crystallinity at the core, with increasing laminate thickness.
Experimental cross sections for deuteron induced nuclear reactions on natural titanium were measured, using the stacked-foil technique and gamma spectrometry, up to 34MeV with beams provided by the ...ARRONAX cyclotron. The experimental cross section values were monitored using the natTi(d,x)48V reaction, recommended by the IAEA. The excitation functions for natTi(d,x)44m,46,47,48Sc are presented and compared with the existing ones and with the TALYS 1.6 code calculations using default models. Our experimental values are in good agreement with data found in the literature. TALYS 1.6 is not able to give a good estimation of the production cross sections investigated in this work. These production cross sections of scandium isotopes fit with the new Coordinated Research Project (CRP) launched by the International Atomic Energy Agency (IAEA) to expand the database of monitor reactions.
•Deuteron induced reactions on natural titanium up to 34MeV.•Monitor reactions database (CRP IAEA).•Experimental values determined using the stacked-foil technique.•Comparison with the TALYS code version 1.6.
Abstract Introduction226 Th ( T1/2 = 31 min) is a promising therapeutic radionuclide since results, published in 2009, showed that it induces leukemia cells death and activates apoptosis pathways ...with higher efficiencies than213 Bi.226 Th can be obtained via the230 U α decay. This study focuses on the230 U production using the232 Th(d,4n)230 Pa( β −)230 U reaction. Methods Experimental cross sections for deuteron-induced reactions on232 Th were measured from 30 down to 19 MeV using the stacked-foil technique with beams provided by the ARRONAX cyclotron. After irradiation, all foils (targets as well as monitors) were measured using a high-purity germanium detector. Results Our new230 Pa cross-section values, as well as those of232 Pa and233 Pa contaminants created during the irradiation, were compared with previous measurements and with results given by the TALYS code. Experimentally, same trends were observed with slight differences in orders of magnitude mainly due to the nuclear data change. Improvements are ongoing about the TALYS code to better reproduce the data for deuteron-induced reactions on232 Th. Conclusions Using our cross-section data points from the232 Th(d,4n)230 Pa reaction, we have calculated the thick-target yield of230 U, in Bq/μA·h. This value allows now to a full comparison between the different production routes, showing that the proton routes must be preferred.
In this study, mercerisation of native cellulose I was achieved in an aqueous sodium hydroxide solution at a concentration of only 1 wt% NaOH by processing at temperatures below 0 °C. This represents ...a tenfold reduction in the use of NaOH to accomplish this very common transformation. The cellulose sample was a form of hydrolysed cotton with a high crystallinity. The samples were mixed with aqueous sodium hydroxide at various concentrations and stored at −17 °C. The samples were then defrosted, neutralised and dried before being analysed by Fourier-transform infrared spectroscopy, wide-angle X-ray diffraction and field-emission scanning electron microscopy. In the route described here, transformation from cellulose I to cellulose II was possible without greatly affecting the crystallinity or the microstructure of the samples.
Low NaOH concentrations at low temperatures allow for easy cellulose mercerisation (polarised optical microscopy).
Cross sections for the (d,n), (d,2n) and (d,4n) reactions on 232Th were measured using the stackedfoil technique with beams provided by the ARRONAX cyclotron. These data are of relevance for the ...production of radionuclides. The measured cross sections were compared with previous measurements as well as with theoretical calculations using the code TALYS.
Cross sections for the (d,n), (d,2n) and (d,4n) reactions on 232Th were measured using the stackedfoil technique with beams provided by the ARRONAX cyclotron. These data are of relevance for the ...production of radionuclides. The measured cross sections were compared with previous measurements as well as with theoretical calculations using the code TALYS.
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