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The Coronavirus disease 2019 (COVID-19) has compelled tourism experts to devise efficient ways to attract visitors. Based on the theory of planned behavior (TPB) model, this study created a comprehensive model of residents’ trust in government performance, perceived risk, and travel intention. The model was tested on 469 Vietnamese residents using confirmatory factor analysis and structural equation modeling. The findings reveal that perceived risk negatively impacts attitudes toward travel, perceived behavioral control, and subjective norms, while trust in government performance positively impacts these categories. Furthermore, attitude toward travel, perceived behavioral control, and subjective norms positively influence a tourist's travel intention. This study offers theoretical and practical insights into how to build safe tourism practices and design appropriate COVID-19 recovery programs in the tourism industry.

MAX phases are layered carbides or nitrides with the general formula Mn+1AXn, which exhibit a unique combination of ceramic- and metal-like properties. The effect of stacking a number (determined by n) remains to be elucidated and a priori is not clear whether, for a given chemistry, n significantly changes the intrinsic deformation behavior of these systems. In this work, we have studied the intrinsic deformation behavior of Tin+1AlCn and Tan+1AlCn (n = 1 … 5) using DFT-based calculations. Surprisingly, the results suggest that the stacking number tends to have a minimal effect on the intrinsic mechanical behavior of the systems studied. [ABSTRACT FROM AUTHOR]

Insufficient availability of molten salt corrosion‐resistant alloys severely limits the fruition of a variety of promising molten salt technologies that could otherwise have significant societal impacts. To accelerate alloy development for molten salt applications and develop fundamental understanding of corrosion in these environments, here an integrated approach is presented using a set of high‐throughput (HTP) alloy synthesis, corrosion testing, and modeling coupled with automated characterization and machine learning. By using this approach, a broad range of CrFeMnNi alloys are evaluated for their corrosion resistances in molten salt simultaneously demonstrating that corrosion‐resistant alloy development can be accelerated by 2 to 3 orders of magnitude. Based on the obtained results, a sacrificial protection mechanism is unveiled in the corrosion of CrFeMnNi alloys in molten salts which can be applied to protect the less unstable elements in the alloy from being depleted, and provided new insights on the design of high‐temperature molten salt corrosion‐resistant alloys. [ABSTRACT FROM AUTHOR]

We have performed ab initio electronic structure calculations and Monte Carlo simulations of frustrated ferroic materials where complex magnetic configurations and chemical disorder lead to rich phase diagrams. With lowering of temperature, we find a ferromagnetic phase which transforms to an antiferromagnetic phase at the magnetostructural (martensitic) phase transition and to a cluster spin glass at still lower temperatures. The Heusler alloys Ni-(Co)-Mn-(Cr)-(Ga, Al, In, Sn, Sb) are of particular interest because of their large inverse magnetocaloric effect associated with the magnetostructural transition and the influence of Co/Cr doping. Besides spin glass features, strain glass behavior has been observed in Ni-Co-Mn-In. The numerical simulations allow a complete characterization of the frustrated ferroic materials including the Fe-Rh-Pd alloys.

Thrombocytosis is usually seen in myeloproliferative neoplasms (MPNs) and associated with thrombohemorrhagic complications. Therapeutic thrombocytapheresis using an automatic cell separator can help to achieve prompt platelet count reduction to decrease the rate of thrombotic events. In this study, we report a single center's experience in managing MPN patients with thrombocytapheresis prior to chemotherapy. Thrombocytapheresis procedures were performed in 185 MPN patients with thrombocytosis between January 2016 and June 2017. The median percentage reduction of platelets was 44.5% and the median percentage removal efficiency was 65.2% for 83 procedures where the waste bag was sampled. Procedures were generally well tolerated with few patients having mild adverse events (13 out of 185 patients). [ABSTRACT FROM AUTHOR]

Recently, it has been predicted that Ta4AlC3 is likely to exhibit an (α-β) polymorphic transformation at temperatures above 1873 K. However, recent X-ray diffraction and transmission electron microscopy experiments suggest on the other hand that the α phase remains stable up to temperatures close to the limit of experimental capabilities and no transition has yet been observed. While the matter has already been settled experimentally, in this work, we re-investigate the phase stability problem in Ta4AlC3 by using first-principles methods. The study was carried out by considering both thermodynamic and mechanical stabilities of the Ta4AlC3 polymorphs. Particularly, finite-temperature Gibbs free energies and elastic properties of the polymorphs were calculated using density functional theory. Calculation results reveal that the α phase continue to be stable even at temperatures exceeding 1875 K, which is in agreement with experimental results reported in literature. [ABSTRACT FROM AUTHOR]

The design of next-generation alloys through the integrated computational materials engineering (ICME) approach relies on multiscale computer simulations to provide thermodynamic properties when experiments are difficult to conduct. Atomistic methods such as density functional theory (DFT) and molecular dynamics (MD) have been successful in predicting properties of never before studied compounds or phases. However, uncertainty quantification (UQ) of DFT and MD results is rarely reported due to computational and UQ methodology challenges. Over the past decade, studies that mitigate this gap have emerged. These advances are reviewed in the context of thermodynamic modeling and information exchange with mesoscale methods such as the phase-field method (PFM) and calculation of phase diagrams (CALPHAD). The importance of UQ is illustrated using properties of metals, with aluminum as an example, and highlighting deterministic, frequentist, and Bayesian methodologies. Challenges facing routine uncertainty quantification and an outlook on addressing them are also presented. [ABSTRACT FROM AUTHOR]

Oligomeric hydroxyaryloxycyclotriphosphazenes P3N3Cln(OC6H5)x(OC6H4OH)y are obtained by the polycondensation of phenoxychlorocyclotriphosphazenes with the general formula P3N3Cl(6 −x)(OC6H5)x (x = 3.1, 4.5) with an excess of resorcinol under homogeneous (pyridine) and heterogeneous (K2CO3) acceptance of HCl in a yield of 60–85%. Full substitution of the chlorine atoms in the specified oligomers (n = 0) under homogenous acceptance of HCl by pyridine is reached only at a molar ratio of phenoxychlorocyclophosphazene : resorcinol = 1 : 12; the formed oligomers contain up to 3% Cl at a ratio of 1 : 6. The structure of the compounds present in the composition of oligohydroxyaryloxycyclotriphosphazenes and their relative concentration are determined by 31P NMR spectroscopy and MALDI-TOF mass spectrometry. [ABSTRACT FROM AUTHOR]

Background: Hyperleukocytosis is commonly seen in acute and chronic leukemias. Therapeutic leukocytapheresis using an automatic cell separator can help to achieve prompt leukoreduction to reduce the rate of thrombotic events and early mortality as well as to prevent tumor lysis syndrome. Aim: In this study, we report a single center's experience in managing leukemia patients with therapeutic leukocytapheresis prior to chemotherapy. Materials and Methods: Leukocytapheresis procedures were performed in 192 leukemia patients (including acute myeloid leukemia [AML], acute lymphoblastic leukemia [ALL], and chronic myeloid leukemia [CML]) with hyperleukocytosis between January and December 2016. Results: Median % reduction of white blood cell (WBC) count was 30.5% and median % removal efficiency was 46.7% for 75 procedures where the waste bag was sampled. WBC removal efficiency strongly depended on diagnosis (and was 71%, 66%, and 39% for ALL, AML, and CML, respectively). Procedures were generally well tolerated with only 9 out of 192 patients having mild adverse effects. Discussion and Conclusion: In the absence of specific guidelines for the management of hyperleukocytosis, leukocytapheresis in association with chemotherapy should be considered early in clinical practice. [ABSTRACT FROM AUTHOR]

In this work, the electronic, structural, elastic, and thermodynamic properties of Ti2AX MAX phases (A = Al or Ga, X = C or N) were investigated using density functional theory (DFT). It is shown that the calculations of the electronic, structural, and elastic properties of these structures, using local density approximation (LDA) and generalized gradient approximation (GGA) coupled with projected augmented-wave (PAW) pseudopotentials, agree well with experiments. A thermodynamic model, which considers the vibrational and electronic contributions to the total free energy of the system, was used to investigate the finite-temperature thermodynamic properties of Ti2AX. The vibrational contribution was calculated using the supercell method, whereas the electronic contribution resulted from one-dimensional integration of electronic density of states (DOSs). To verify the model, the specific heats of pure elements were calculated and compared to experimental data. The DFT-D2 technique was used to calculate the heat capacity of graphite, taking into account the van der Waals (vdW) effect. Good agreement between the calculations and experiments for the specific heats of graphite and other pure elements lends validity to the approach used. The calculated results for the specific heats of Ti2AlC and Ti2AlN match well with experimental data. These strengthen the results of specific heats of Ti2GaC and Ti2GaN as well as other calculated thermodynamic properties, including the energies of formation and thermal expansion coefficient. [ABSTRACT FROM AUTHOR]

Abstract: Martensitic transformations of rapidly quenched and less‐rapidly cooled Heusler alloys of type Ni–Mn–X with X=Ga, In, and Sn are investigated by ab initio calculations. For alloys rapidly cooled from 1173 K, we obtain the well‐known magnetocaloric properties near the magnetocaloric phase transition. For the less‐rapidly cooled alloys with secondary heat treatment these magnetocaloric properties start to change considerably, because each alloy transforms during temper‐annealing into a dual‐phase composite alloy. These two phases are identified to be cubic stoichiometric Ni2MnX and tetragonal disordered NiMn. [ABSTRACT FROM AUTHOR]

Despite the fact that there is evidence for the important role that vacancies play in the martensitic transformation (MT) behavior of metamagnetic shape memory alloys (MMSMAs), little theoretical – and even experimental – work on the thermodynamics and kinetics of point defects in these systems has been carried out. Since the MT behavior of MMSMAs has a great influence on their magneto‐caloric response, investigating the vacancy evolution in MMSMAs has potentially a significant technological impact. Scarcity of studies may be due to the limited characterization capability available for studying vacancy properties as well as their impacts on the materials performance. The current work seeks to introduce the application of the grand‐canonical dilute‐solution model to the investigation of equilibrium (thermal) populations of point defects in Ni2MnGa, used as a prototypical MMSMA. The thermodynamic model is coupled to first‐principles calculations of the energetics of defect‐containing supercell structures. Such characterization capability allows for more realistic investigations of MMSMAs with the vacancy degree of freedom taken into account and subsequently opens up many interesting research topics. Here we demonstrate the capability of the first principles based characterization method by investigating the role of vacancy concentration in the kinetics of order–disorder (ODO) process and the MT temperature of Ni2MnGa. [ABSTRACT FROM AUTHOR]

Martensitic transformations of rapidly quenched and less rapidly cooled Heusler alloys of type Ni–Mn–X with X = Ga, In, and Sn are investigated by ab initio calculatioms. For the rapidly cooled alloys, we obtain the magnetocaloric properties near the magnetocaloric transition. For the less rapidly quenched alloys these magnetocaloric properties start to change considerably, each alloy transforms during temper‐annealing into a dual‐phase composite alloy. The two phases are identified to be cubic Ni–Mn–X and tetragonal NiMn. [ABSTRACT FROM AUTHOR]

In this work, thermodynamic and kinetic diffusivities of uranium–niobium (U–Nb) are re-assessed by means of the CALPHAD (CALculation of PHAse Diagram) methodology. In order to improve the consistency and reliability of the assessments, first-principles calculations are coupled with CALPHAD. In particular, heats of formation of γ -U–Nb are estimated and verified using various density-functional theory (DFT) approaches. These thermochemistry data are then used as constraints to guide the thermodynamic optimization process in such a way that the mutual-consistency between first-principles calculations and CALPHAD assessment is satisfactory. In addition, long-term aging experiments are conducted in order to generate new phase equilibria data at the γ 2 / α + γ 2 boundary. These data are meant to verify the thermodynamic model. Assessment results are generally in good agreement with experiments and previous calculations, without showing the artifacts that were observed in previous modeling. The mutual-consistent thermodynamic description is then used to evaluate atomic mobility and diffusivity of γ -U–Nb. Finally, Bayesian analysis is conducted to evaluate the uncertainty of the thermodynamic model and its impact on the system's phase stability. [ABSTRACT FROM AUTHOR]

In this work, we calculate the structural, elastic, thermodynamic properties of Ti 3 SiC 2 and Ti 3 AlC 2 using a density functional theory (DFT) framework. The vibrational, electronic and quasi-harmonic contributions as well as an anharmonic correction to the total free energy of the system are computed and extrapolated to determine the finite-temperatures properties of the systems. Charge densities, electron localization functions (ELF), the electronic density of states (EDOS) and the vibrational density of states (VDOS) are analyzed in order to deepen our understanding of the interactions giving rise to the calculated properties. Calculated values of Young’s modulus, Heat Capacity and Coefficient of Thermal Expansion (CTE) show good agreement with experimental values. [ABSTRACT FROM AUTHOR]

Highlights: [•] Finite-temperature elastic properties of Ti2AlC and Ti2AlN were calculated. [•] Good agreement between calculation and experiment for Ti2AlC verified the approach. [•] Prediction of finite-temperature elastic properties for Ti2AlN was presented. [•] The approach’s applicability is limited to high temperatures, 1600K for this work. [ABSTRACT FROM AUTHOR]

In this work, the effects of small ternary additions to B2 NiTi structures was investigated through DFT calculations. The analysis considered deviations from stoichiometry arising from either simple substitution of host atoms in a given sublattice or from the formation of anti-sites. The calculations enabled the determination of the site preference of X ternary additions. Moreover, the results suggest that ternary additions located in the central region of the transition metal group across all periods tend to occupy Ni sites due to favorable X–Ti nearest neighbor (NN) interactions. This occupancy is achieved through substitution or through the generation of anti-site defects. On the other hand, ternary additions at both ends of a given transition metal row tend to occupy Ti sites due to favorable X–Ni NN interactions. Once site preferences are determined, the effect of alloying on the thermodynamic and mechanical properties of B2 NiTi–X structures are presented and trends are discussed. [ABSTRACT FROM AUTHOR]