| 1. |
- Chernogorova, O., et al.
(författare)
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Structure and properties of superelastic hard carbon phase created in fullerene-metal composites by high temperature-high pressure treatment
- 2012
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 111:11
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Tidskriftsartikel (refereegranskat)abstract
- Treatment of a fullerene soot extract and metal (Co) powder mixture under pressure of 5 and 8 GPa at 1000 °C leads to the transformation of fullerites into superelastic hard phase (SHP) and to simultaneous sintering of the powder mixture to nonporous composite material reinforced by the SHP particles. The structure of the SHP particles reveals a topological relation to the initial fullerite crystal morphology. Upon indentation, the SHP particles demonstrate an elastic recovery of up to 96. The universal microhardness of the SHP particles HU=26 GPa, and their microhardness HV = 35 GPa. A high ratio between the microhardness and elastic modulus (HV/E = 0.19-0.21) of the SHP particles makes them perspective candidates for design of materials with superior wear resistance and tribological properties.
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| 2. |
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| 3. |
- Kostin, Alexander I., et al.
(författare)
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Impact of pathogen reduction methods on immunological properties of the COVID-19 convalescent plasma
- 2021
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Ingår i: Vox Sanguinis. - : Wiley. - 0042-9007 .- 1423-0410. ; 116:6, s. 665-672
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Tidskriftsartikel (refereegranskat)abstract
- Background and objectives: COVID-19 convalescent plasma is an experimental treatment against SARS-CoV-2. The aim of this study is to assess the impact of different pathogen reduction methods on the levels and virus neutralizing activity of the specific antibodies against SARS-CoV2 in convalescent plasma. Materials and methods: A total of 140 plasma doses collected by plasmapheresis from COVID-19 convalescent donors were subjected to pathogen reduction by three methods: methylene blue (M)/visible light, riboflavin (R)/UVB and amotosalen (A)/UVA. To conduct a paired comparison, individual plasma doses were divided into 2 samples that were subjected to one of these methods. The titres of SARS-CoV2 neutralizing antibodies (NtAbs) and levels of specific immunoglobulins to RBD, S- and N-proteins of SARS-CoV-2 were measured before and after pathogen reduction. Results: The methods reduced NtAbs titres differently: among units with the initial titre 80 or above, 81% of units remained unchanged and 19% decreased by one step after methylene blue; 60% were unchanged and 40% decreased by one step after amotosalen; after riboflavin 43% were unchanged and 50% (7%, respectively) had a one-step (two-step, respectively) decrease. Paired two-sample comparisons (M vs. A, M vs. R and A vs. R) revealed that the largest statistically significant decrease in quantity and activity of the specific antibodies resulted from the riboflavin treatment. Conclusion: Pathogen reduction with methylene blue or with amotosalen provides the greater likelihood of preserving the immunological properties of the COVID-19 convalescent plasma compared to riboflavin.
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| 4. |
- Lukina, I N, et al.
(författare)
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Effect of synthesis parameters on the structure and properties of carbon particles formed from amorphous fullerites
- 2020
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Konferensbidrag (refereegranskat)abstract
- The effect of high-pressure synthesis temperature on the structure and indentation characteristics of the superelastic hard carbon formed from amorphous fullerites and on the tribological properties of the Co-based composite materials (CM) reinforced by the particles of such carbon has been studied by Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), indentation measurements, and tribological tests. It is shown that ball milling (for 48 h) of C60 fullerite crystals results in the amorphization of the product of fullerite transformation upon their high-pressure treatment at temperatures above the stability limit of fullerene molecule (~800°C). An increase in synthesis temperature at 8 GPa from 800°C to 1200°C leads to a gradual graphitization of the structure of amorphous fullerite derived carbon. This decreases its hardness and indentation modulus from 32 to 18 GPa and from 256 to 95 GPa, respectively, and increases the elastic recovery (from 80% to 86%). The best tribological characteristics of the CM are attained at the maximum particle hardness, which is realized in the CM synthesized at 800°C. When the synthesis temperature is elevated to 1200°C, the friction coefficient and wear rate of the CM increase, but they remain substantially lower than those of the matrix cobalt.
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| 5. |
- Chernogorova, Olga P., et al.
(författare)
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Indentation behaviour of superelastic hard carbon
- 2016
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Ingår i: Philosophical Magazine. - : Informa UK Limited. - 1478-6435 .- 1478-6443. ; 96:32-34, s. 3451-3460
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Tidskriftsartikel (refereegranskat)abstract
- Superelastic hard carbon particles widely varying in structure andproperties have been studied by instrumented microindentationtechnique. The carbon particles up to 200 μm in size were producedby fullerene collapse upon high-pressure high-temperature treatmentof metal–fullerene powder mixture with simultaneous sintering ofmetal matrix composite materials (CM) reinforced by the particles.The structure and properties of the carbon particles were controlledby changing synthesis parameters and the state (composition andstructure) of the parent fullerite crystals. The specific features of theinstrumented indentation behaviour of the particles were studied asa function of their hardness. Mechanical properties of the particlestested at loads of up to 1970 mN exhibit an indentation size effect,which becomes more pronounced with increasing hardness of thecarbon particles. Upon holding at a constant load, the fullerenederivedcarbon particles undergo unrecoverable deformation, and theindentation creep CIT increases with increasing particle hardness. Anincrease in hardness of the reinforcing carbon particles substantiallyimproves the wear resistance of the CM and decreases their frictioncoefficient.
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| 6. |
- Lukina, I N, et al.
(författare)
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Effect of high-pressure treatment temperature on the structure of carbon phases formed from C60 fullerites under pressure
- 2019
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Ingår i: Fourth interdisciplinary scientific forum with international participation "New materials and promising technologies" 27–30 November 2018, Moscow, Russian Federation. - : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- The synthesis of metal-matrix composite materials reinforced with superelastic hard carbon particles formed from C60 fullerites includes heating of the metal-fullerite powder mixture to temperatures above 800C under pressure. The structure evolution of the carbon particles upon heating from 700 to 800 C at a pressure of 5 GPa has been studied in detail by Raman spectroscopy and indentation hardness measurements. It is shown that the structure of the carbon particle passes the stage of a nanoscale mixture of one- and two-dimensional polymers with the resulting atomic superelastic solid phase. The determining properties of the carbon particles such as superplasticity and high hardness are attained before the complete disappearance of polymerized fullerites, the remnants of which are responsible for the disintegration of the material upon scratching.
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| 7. |
- Voitsekhovskaja, O. V., et al.
(författare)
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Photosynthetic activity as assessed via chlorophyll a fluorescence suggests a role of potassium channels in root to shoot signaling
- 2020
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Ingår i: Photosynthetica (Praha). - : Institute of Experimental Botany. - 0300-3604 .- 1573-9058. ; 58:2, s. 608-621
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Tidskriftsartikel (refereegranskat)abstract
- Potassium is indispensable for plant growth. Recently, a role of K+ channels has emerged in sensing and transducing stress and nutrient status. Tetraethylammonium (TEA(+)) is a specific blocker of K+ transport and affects K+ channel gene expression. Two barley varieties with contrasting salinity tolerance, and a chlorophyll b-less mutant, were grown either in the presence of TEA(+) alone or combined with NaCl, at two different concentrations of external K+ and Ca2+, and were analyzed nine days after germination. Chlorophyll a transients monitored via JIP-tests were used to evaluate the state of the photosynthetic machinery. In contrast to reported responses to K+ deficiency, TEA(+) inhibited shoot growth while inducing root growth and increasing photosynthetic performance. Both TEA(+) and NaCl induced the appearance of negative K-bands in OJIP kinetics and an increase in PIABS, indicating a stimulation of photosynthesis by increased sink strength in the context of root to shoot signaling.
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