Abstract
In this work, we investigated structure and magnetic properties of Mn
65
Ga
20
Al
15−x
Cu
x
(x = 0, 5, 10 and 15) alloy ribbons prepared by melt-spinning method combined with annealing. The ...annealing temperature was varied from 250 °C to 350 °C, and the annealing time was changed from 5 h to 20 h. Concentration of Cu and annealing process significantly influence on the formation of the desired phases in the alloy ribbons. The D0
22
-type Mn
3
Ga crystalline phase with the hexagonal structure, which characterizes hard magnetic property of Mn-Ga based alloys, is enhanced after an appropriate annealing process. The change of grain size after annealing also contributes to the increased coercivity of the alloy ribbons. The highest coercivity of 12.9 kOe and saturation magnetization of 18.7 emu g
−1
are achieved on the alloy ribbons with Cu concentration of 10%. The simultaneous enhancement of these magnetic parameters has an important significance for application possibility of the Mn-Ga based alloys.
•Microstructure and magnetic properties of Mn54Bi46−xSnx melt-spun ribbons.•Influence of Sn content and annealing process on formation of LTP-MnBi.•Refinement of grains in Mn-Bi alloys by addition of ...Sn.•Enhancement of saturation magnetization of Mn-Bi-Sn melt-spun ribbons by annealing.
In this work, the phase formation, microstructure and magnetic properties of Mn54Bi46−xSnx (x = 0, 1, 2, 3 and 4) alloy ribbons fabricated by melt-spinning method combined with annealing were investigated. The fraction of the low-temperature MnBi phase (LTP-MnBi) depends not only on the Sn concentration but also on the annealing regime. In the as-quenched ribbons, the fraction of the LTP-MnBi decreases monotonically from 38.1 to 21.1 wt% when the Sn concentration increases from 0 to 4 at%. Meanwhile, the fraction of this phase increases significantly from 69.0 to 83.2 wt% when the Sn concentration changes from 0 to 2 at% and tends to decrease upon further increasing the Sn concentration to 4 at% for the ribbons annealed at 250 °C for 16 h. Saturation magnetization, Ms, of the annealed samples changes consistently with the fraction of LPT-MnBi and reaches a maximum value of 70.4 emu/g in the sample with Sn concentration of 2 at%. The addition of Sn also aids in refining the grains, leading to an improvement in the hard magnetic properties of the material. The coercivity, Hc, of the alloy ribbons tends to increase as the Sn concentration increases and changes non-monotonically with annealing time. The maximum energy product, (BH)max, reached 5.5 MGOe in the sample with x = 2, demonstrating the promise of Mn-Bi based alloys in practical applications. The density functional theory calculations were also performed to clarify the effect of Sn addition. The calculated results confirmed the decrease in the lattice parameters with Sn substitution in the experimental data. The total magnetic moment per formula unit and the evaluated saturation magnetization are 3.62 µB and 78.28 emu/g, respectively, for Sn substitution of ∼3.1 at%. (Although the total magnetic moment decrease with doping, the saturation magnetization per unit mass could be improved.)
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The chemical investigation of the stems of Knema globularia led to the isolation of two new benzoquinones derivatives, embenones A and B (1 and 2), along with three known compounds (3–5). The ...structures of the isolated compounds were determined using spectroscopic techniques, including HRESIMS, 1D and 2D NMR, in conjunction with comparison to existing literature data. Compounds 1 and 2 represent new carbon skeletons in nature. Furthermore, all isolated compounds were evaluated for their α‐glucosidase inhibitory activity, with compounds 1–3 exhibiting superior potency relative to the positive control (acarbose, IC50 331 μM). Their IC50 values ranged from 1.40 to 96.1 μM.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Alloy ribbons of Ni50−xCoxMn50−yAly (x = 5, 6, 7, 8 and 9; y = 18 and 19) were fabricated by using melt-spinning method. By varying Co and Al concentrations, the formation of crystalline phases, ...structural transformations and magnetic phase transitions can be tuned as desired. With high Al and Co concentrations, only a ferromagnetic-paramagnetic (FM-PM) transition of the austenitic phase occurs in the range of 350–450 K. While there is an additional weak ferromagnetic- ferromagnetic (WFM-FM) transition corresponding to the martensitic-austenitic (M-A) structural transformation for the ribbons with low Al and Co concentrations. The M-A transformation temperature of the alloy ribbons can be obtained in the range of 150–360 K. An anomalous change in structure and magnetic properties was observed in the ribbon sample with Co and Al concentrations of 8 and 18 at%, respectively. The external magnetic field has a pronounced effect on the M-A transformation and tends to shift this process towards lower temperatures.
•Structure and magnetic properties of Ni50−xCoxMn50−yAly rapidly solidified alloys.•Influence of Co and Al contents on structural transformation and magnetic transition.•Coexistence of different crystalline phases in Heusler magnetic shape memory alloys.•Tuning structural transformation and magnetic transition of Ni-Co-Mn-Al alloys.•Transformation of metamagnetic phase in Ni-Co-Mn-Al rapidly solidified alloys.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
AutoDock Vina (Vina) achieved a very high docking‐success rate, p^, but give a rather low correlation coefficient, R, for binding affinity with respect to experiments. This low correlation can be an ...obstacle for ranking of ligand‐binding affinity, which is the main objective of docking simulations. In this context, we evaluated the dependence of Vina R coefficient upon its empirical parameters. R is affected more by changing the gauss2 and rotation than other terms. The docking‐success rate p^ is sensitive to the alterations of the gauss1, gauss2, repulsion, and hydrogen bond parameters. Based on our benchmarks, the parameter set1 has been suggested to be the most optimal. The testing study over 800 complexes indicated that the modified Vina provided higher correlation with experiment Rset1=0.556±0.025 compared with RDefault=0.493±0.028 obtained by the original Vina and RVina1.2=0.503±0.029 by Vina version 1.2. Besides, the modified Vina can be also applied more widely, giving R≥0.500 for 32/48 targets, compared with the default package, giving R≥0.500 for 31/48 targets. In addition, validation calculations for 1036 complexes obtained from version 2019 of PDBbind refined structures showed that the set1 of parameters gave higher correlation coefficient (Rset1=0.617±0.017) than the default package (RDefault=0.543±0.020) and Vina version 1.2 (RVina1.2=0.540±0.020). The version of Vina with set1 of parameters can be downloaded at https://github.com/sontungngo/mvina. The outcomes would enhance the ranking of ligand‐binding affinity using Autodock Vina.
A new set of empirical parameters of AutoDock Vina was proposed. The accuracy of affinity prediction was significantly increased from RDefault=0.493±0.028 to Rset1=0.556±0.025 over 800 testing complexes. Over 1036 validating complexes, the proposed parameter formed Rset1=0.617±0.017, which is rigidly larger than the default package (RDefault=0.543±0.020) and Vina version 1.2 (RVina1.2=0.540±0.020).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•An original procedure for selecting the best model for extreme rainfall distribution.•An identification of the best extreme rainfall distribution for Ontario region.•A performance comparison of ten ...different distributions for extreme rainfalls.•Three top distributions GNO, GEV, and PE3 were found using a large study dataset.•The GEV was recommended as the best distribution for Ontario extreme rainfalls.
Many probability distributions have been developed to model the annual maximum rainfall series (AMS). However, there is no general agreement as to which distribution should be used due to the lack of a suitable evaluation method. This paper presents hence a general procedure for assessing systematically the performance of ten commonly used probability distributions in rainfall frequency analyses based on their descriptive as well as predictive abilities. This assessment procedure relies on an extensive set of graphical and numerical performance criteria to identify the most suitable models that could provide the most accurate and most robust extreme rainfall estimates. The proposed systematic assessment approach has been shown to be more efficient and more robust than the traditional model selection method based on only limited goodness-of-fit criteria. To test the feasibility of the proposed procedure, an illustrative application was carried out using 5-min, 1-h, and 24-h annual maximum rainfall data from a network of 21 raingages located in the Ontario region in Canada. Results have indicated that the GEV, GNO, and PE3 models were the best models for describing the distribution of daily and sub-daily annual maximum rainfalls in this region. The GEV distribution, however, was preferred to the GNO and PE3 because it was based on a more solid theoretical basis for representing the distribution of extreme random variables.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Three quantile-based downscaling methods are systematically intercompared.•Performance of downscaling methods in producing observed quantiles can be divergent.•Downscaling methods with divergent ...functionality generate dissimilar future extremes.•Climate change can alter the current design storms under certain risk levels.•A risk-based approach is suggested to choose future design storms under uncertainty.
Local characteristics of extreme rainfall quantiles, manifested through Intensity-Duration-Frequency (IDF) curves, are key to infrastructure design. Due to climate change, rainfall extremes are subject to changes, it is, therefore, crucial to explore the potential impacts these changes will have on design storms. A new strain of methodologies, quantile-based downscaling approaches, have recently been proposed to exclusively downscale extreme rainfall quantiles obtained from Global Climate Models (GCMs). These approaches, however, have not been systematically intercompared and the uncertainties related to assigning future design storms are poorly understood. This study evaluates the functionality of three quantile-based downscaling methods during the historical and future periods in Montreal, Canada. Results show that the performance of quantile-based downscaling approaches in reproducing observed extreme quantiles can be divergent. At lower return periods, however, differences between the three schemes are not significant. Similar performances for reproducing historical rainfall extremes, however, does not necessarily imply similar future projections due to the different functionalities of the three approaches in mapping GCM projections into finer scales. Despite these uncertainties, the total projection range of future rainfall extremes are, in many cases, comparable to the confidence interval of the parametric probability distribution when fitted to the observed annual maximum rainfall series. A risk-based approach to accommodate this uncertainty in vulnerability assessments through evaluating potential alterations in historical rainfall extremes using an ensemble projection coming from multiple downscaling approaches is suggested. This allows for the selection of design storms based on the acceptable level of risk and given budgetary and operational restrictions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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