10,490 research outputs found
Mechanisms of Mn efficiency in barley / by Chunyuan Huang.
Full text linkBibliography: leaves 131-153.xiii, 153 leaves : ill. (some col.) ; 30 cm.This thesis investigates the mechanisms of manganese (Mn) efficiency (genetic tolerance to Mn-deficient soils) in barley (Hordeum vulgare L.) at both physiological and molecular levels.Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 199
Theoretical investigation on radiation tolerance of Mn+1 AX(n) phases
No full textTernary M(n + 1)AX(n) phases with layered hexagonal structures, as candidate materials used for next-generation nuclear reactors, have shown great potential in tolerating radiation damage due to their unique combination of ceramic and metallic properties. However, Mn + 1AXn materials behave differently in amorphization when exposed to energetic neutron and ion irradiations in experiment. We first analyze the irradiation tolerances of different M(n + 1)AX(n) (MAX) phases in terms of electronic structure, including the density of states ( DOS) and charge density map. Then a new method based on the Bader analysis with the first-principle calculation is used to estimate the stabilities of MAX phases under irradiation. Our calculations show that the substitution of Cr/V/Ta/Nb by Ti and Si/Ge/Ga by Al can increase the ionicities of the bonds, thus strengthening the radiation tolerance. It is also shown that there is no obvious difference in radiation tolerance between Mn (+ 1)AC(n) and Mn (+ 1)AN(n) due to the similar charge transfer values of C and N atoms. In addition, the improved radiation tolerance from Ti3AlC2 to Ti2AlC ( Ti3AlC2 and Ti2AlC have the same chemical elements), can be understood in terms of the increased Al/TiC layer ratio. Criteria based on the quantified charge transfer can be further used to explore other M(n + 1)AX(n) phases with respect to their radiation tolerance, playing a critical role in choosing appropriate MAX phases before they are subjected to irradiation in experimental test for future nuclear reactors
Mn-Doped Highly Dispersed RuO2 Catalyst with Abundant Oxygen Vacancies for Efficient Decarboxylation of lLysine to Cadaverine
No full textChemical
decarboxylation of l-lysine is a promising route
for producing cadaverine, which is the key monomer of new polyamide,
polyurethane, and nylon materials. Currently, the wide application
of Ru-based catalysts is restricted by its low efficiency which was
mainly caused by the severe agglomeration of ruthenium nanoparticle.
In this study, manganese (Mn) doped ruthenium oxide catalyst was synthesized
through the wetness impregnation method with Beta zeolite as the candidate
support for efficient decarboxylation of l-lysine to cadaverine.
Structure characterization showed that RuO2 was the main
phase of ruthenium oxide nanoparticles. The prepared Ru–Mn/Beta
catalysts exhibited a high dispersion of ruthenium oxide nanaoparticle
on Beta, which maximized the utilization of active sites. Meanwhile,
abundant oxygen vacancies were generated after Mn doping to balance
the charge of the disturbed long-term periodic structure in the RuO2 crystalline, which greatly facilitated the adsorption and
activation of l-lysine by the capture of carboxylic groups.
A full conversion was obtained with Ru–Mn/Beta, and a selectivity
of cadaverine up to 54% was reached in a short time of 1.5 h. The
cadaverine production rate in Ru–Mn/Beta was 60.8 mg/L/min,
which was almost triple that in Ru/Beta (17.7 mg/L/min). The synergetic
catalysis of metal active sites and oxygen vacancies provides a new
opportunity to design efficient catalyst of decarboxylation of amino
acids
Mn-Doped RuO<sub>2</sub> Nanocrystals as Highly Active Electrocatalysts for Enhanced Oxygen Evolution in Acidic Media
No full textCurrently, RuO2 is a benchmark acidic oxygen
evolution
reaction (OER) catalyst. Nevertheless, its wide applications are always
restricted by slow dynamics and limited durability. This paper reports
a type of Mn-doped RuO2 nanocrystals for boosting the OER
catalytic performance in acidic media. The catalyst (named Mn-RuO2) is prepared through annealing of Ru-exchanged Mn-based derivative
at 300 °C. Such Mn-RuO2 exhibits excellent acidic
OER activity, with an overpotential of 158 mV at 10 mA cm–2 and a stability of 5000 cycles in the presence of sulfuric acid
(0.5 mol/L). Both structural characterization and theoretical analysis
show that the Mn doping in RuO2 can tune the d-band center
of Ru active sites and lower antibonding surface-adsorbate states,
which leads to a decreased free energy of the rate-determining step,
ultimately enhancing the intrinsic activity of RuO2
Pot size affects expression of Mn efficiency in barley
No full textMn efficiency is defined here as an ability of a genotype to grow and yield well in a soil which is limiting in available Mn for a standard genotype (Graham, 1984). Screening for Mn efficiency in soil-based pot testing had been producing inconsistent results, and thus improvement of pot screening became an objective. One possible factor, pot size was examined as the cause, using two sizes of pot. In large pots, the expectation of higher dry matter and shoot Mn concentration in a Mn-efficient genotype compared to a Mn-inefficient genotype was realised over a wide range of Mn supply, whereas in small pots, the genotypic differences were expressed at only one, low rate of Mn supply (10 mg kg soil-1). Plants in the small pots strongly responded to root restriction by decreasing yields and increasing root/shoot ratios and Mn concentrations of shoots. The critical value of Mn concentration for shoot growth was not affected by the small pots, but the Mn mobilization by plants might be affected in the small pots. The practical outcome of these results is that using an adequate size of pot and measuring the Mn concentration of shoots, soil-based pot screening for Mn efficiency can be improved.Chunyuan Huang, Michael J. Webb and Robin D. Graha
Haemolymph parameters of Pacific white shrimp (Litopenaeus vannamei) infected with Taura syndrome virus.
No full textNonlinear influence of excess Mn on the magnetoelastic transition in (Mn,Cr)<sub>2</sub>Sb
No full textThe influence of excess Mn on the magnetoelastic ferromagnetic-to-antiferromagnetic transition Tt in the magnetocaloric compound (Mn,Cr)2Sb has been studied. With increasing excess Mn the magnetoelastic transition temperature for (Mn,Cr)2Sb initially increases and then decreases. This trend is accompanied by a strong reduction of the (Mn,Cr)Sb secondary phase. With increasing excess Mn a higher Cr content was found in the (Mn,Cr)Sb secondary phase in comparison to the matrix phase. This competition for Cr leads to a nonlinear dependence of Tt with increasing excess Mn at a fixed nominal Cr content. However, we observed that Tt depends linear on the c/a ratio for a wide range of temperatures from 170 to 350 K. A compositional diagram of the c/a ratio was constructed to assist the selection of (Mn,Cr)2Sb alloys with a desired transition temperature.RST/Fundamental Aspects of Materials and Energ
Anomalous photoluminescence of InAs quantum dots implanted by Mn ions
No full textThe photoluminescence (PL) of Mn-implanted quantum dot (QD) samples after rapid annealing is studied. It is found that the blue shift of the PL peak of the QDs, introduced by the rapid annealing, decreases abnormally as the implantation dose increases. This anomaly is probably related to the migration of Mn atoms to the InAs QDs during annealing, which leads to strain relaxation when Mn atoms enter InAs QDs or to the suppression of the inter-diffusion of In and Ga atoms when Mn atoms surround QDs. Both effects will suppress the blue shift of the QD PL peaks. The temperature dependence of the PL intensity of the heavily implanted QDs confirms the existence of defect traps around the QDs. (c) 2006 Elsevier B.V. All rights reserved
Surface Oxidation and Wettability of Fe–Mn and Fe–Mn–Si-Alloyed Steel After Annealing
No full textThe surface oxidation and wettability of Mn and Si-alloyed steel after annealing at different conditions are studied with scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and a so-called de-wetting method. After exposure at 950 °C for 1 hour in an Ar + 5 vol pct H2 gas atmosphere with dew points (DP) ranging from – 40 °C to 10 °C, oxides were observed along the grain boundaries or dispersed on the surface for the Fe–1.8 Mn steels while a continuous oxides layer was formed on Fe–1.9 Mn–0.94 Si steels (composition in weight fractions). The oxides formed at different DPs were predicted based on thermodynamic calculations. (Fe,Mn)O was formed on Fe–1.8 Mn steel at the whole range of DPs, while the oxide phase on Fe–1.9 Mn–0.94 Si steel depends on the DP. At low-DP SiO2 were formed and with increasing the DP (Fe,Mn)SiO3 or (Fe,Mn)SiO3 + (Fe,Mn)2SiO4 were formed and finally (Fe,Mn)2SiO4 were formed. An increase of the fraction of Fe in the oxide with increasing DP for both steels was observed with XPS analysis. As a measure for the surface wettability, the contact angle of Pb droplets on the annealed steels surfaces was determined with SEM and image analysis software. Also, the contact angle of Pb on pure Fe and on the Mn and Si alloyed steels free of surface oxides was measured for comparison. The results show that the contact angle of Pb on the steel surfaces after annealing decreases with increasing DP. This improved wettability with increasing dew point is related to the Fe fraction of the oxides formed on the surface.Team Kevin RossiTeam Maria Santofimia NavarroTeam Marcel Herman
Temperature-Dependent Microstructural Evolution of Al-Rich Medium-Mn Steel During Intercritical Annealing
No full textMedium-Mn automotive sheet steels require optimized heat-treatment processes to obtain benefits caused by strain-induced martensitic transformation of retained austenite (RA) during sheet metal forming or crash events. The intercritical annealing (IA) approach at different temperatures in a range of 640 °C to 800 °C is proposed in the study for a 5Mn hot-rolled medium-Mn sheet steel. The experiments were performed in terms of dilatometry. The analysis of the cooling curves allowed development of a new method for calculating the high-temperature phase equilibrium. The calculations were validated by modeling with JMatPro and experimentally verified by X-ray diffraction (XRD). The microstructure evolution was characterized using light optical microscopy and scanning electron microscopy (SEM), including electron backscatter diffraction (EBSD). The quantitative determination of the fraction, morphology, chemical composition, and stability of the RA was done. Mechanical properties were determined by hardness measurements. The research showed a substantial influence of the IA temperature on the RA fraction and chemical stability and properties of medium-Mn Al-alloyed steel. At temperatures of 680 °C and 700 °C, the largest fraction of over 35 pct of stable RA was obtained, which does not transform to martensite during cooling.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Kevin Ross
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