Two-dimensional (2D) magnets with room temperature ferromagnetism and semiconductors with moderate band gap and high carrier mobility are highly desired for applications in nanoscale electronics and ...spintronics. By performing the first-principles calculations, we investigate novel Fe, Co, Ni carbide based pristine (M
2
C) and functionalized (M
2
CT
2
, T: F, O, OH) MXenes. Our calculations show that Fe
2
C, Co
2
C, Ni
2
C, Fe
2
CF
2
, Fe
2
CO
2
, Fe
2
C(OH)
2
, Co
2
CF
2
, Co
2
C(OH)
2
and Ni
2
CF
2
are dynamically and mechanically stable. More importantly, Fe
2
C, Co
2
C, Fe
2
CF
2
and Fe
2
C(OH)
2
exhibit intrinsic ferromagnetism (magnetic moments 2-5
μ
B
per unit cell). Monte Carlo simulations suggest high Curie temperatures of 590 and 920 K for Fe
2
C and Fe
2
CF
2
, respectively, at the HSE06 level owing to the large spin magnetic moments and strong ferromagnetic coupling. Based on the deformation potential theory, we predict high and anisotropic hole mobility (0.2-1.4 × 10
4
cm
2
V
−1
s
−1
) for semiconducting Fe
2
CO
2
and Co
2
C(OH)
2
. Additionally, Ni
2
CF
2
demonstrates highly anisotropic electron mobility together with a direct band gap. Our results further show the effectiveness of surface functionalization in modulating the electronic and magnetic properties and broadening the properties of MXenes to achieve long-range intrinsic ferromagnetism well above room temperature and high carrier mobility.
MXenes have intrinsic and robust ferromagnetism well above room temperature as well as high and anisotropic carrier mobility.
Capability of satellite-aided ballistic capture Luo, Z.-F.; Topputo, F.
Communications in nonlinear science & numerical simulation,
July 2017, 2017-07-00, 20170701, Letnik:
48
Journal Article
Recenzirano
Odprti dostop
•An existing method is modified to account for the presence of planets’ natural moons.•The role of the moons in improving ballistic capture orbits is discussed with case studies.•Comparisons against ...the case of moon-free scenario are given.
In this paper we study a special instance of ballistic capture dynamics: the case in which the capture orbit about a planet experiences a close passage to one or more of its natural satellites. The capability of the satellites in improving ballistic capture is assessed. The dynamical framework considers at least the gravitational attractions of the Sun, the planet, and its satellites, all acting on a massless particle. The effect of the satellites is introduced explicitly by modifying a previously developed method, which relies on three-dimensional stable sets and n-body dynamics with precise ephemeris. Once a stability criterium is defined, initial conditions defined over a computational grid are integrated forward and backward. This allows us to classify orbits into different sets. Ballistic capture orbits with prescribed features are generated by manipulating these sets. Two indices, namely the hyperbolic velocity and the stability index, are used to assess the performance of pre- and post-capture portions, respectively. A Pareto frontier is used to extract orbits of practical interest. Case studies are performed in the context of Earth and Jupiter environments. Comparing to the situation with no moons, the satellite-aided ballistic capture can evidently increase the pre-capture energy and post-capture stability, so making it possible to have permanent capture of a particle at zero-cost. This is a desirable feature in mission design.
► Weldments were done with laser shock processing impacts after cavitation erosion. ► Laser shock processing enhanced the erosion and corrosion resistance of weldments. ► Tensile residual stress and ...surface roughness decreased by laser shock processing. ► Microstructure was observed to explain the improvement by laser shock processing. ► Obvious passivation areas occurred with laser shock processing impacts.
Effects of laser shock processing (LSP) on electrochemical corrosion resistance of weldments after cavitation erosion were investigated by X-ray diffraction (XRD) technology, scanning electron microscope (SEM), roughness tester and optical microscope (OM). Some main factors to influence erosion and corrosion of weldments, residual stresses, surface roughness, grain refinements and slip, were discussed in detail. Results show that LSP impacts can induce compressive residual stresses, decrease surface roughness, refine grains and generate the slip. Thus, the erosion and corrosion resistance with LSP impacts is improved.
•To assess the role played by the dynamical model and planetary eccentricity in the ballistic capture about a planet.•To study the effect of planet true anomaly, in a quantitative and qualitative ...way.•To evaluate the effect of spatial distribution on ballistic capture orbits.
Analysis of ballistic capture orbits in Sun–planet systems is conducted in this paper. This mechanism utilizes purely gravitational forces, and may occur in non-Keplerian regimes. Ballistic capture orbits are generated by proper manipulation of sets of initial conditions that satisfy a simple definition of stability. Six Sun–planet systems are considered, including the inner planets, Jupiter, and Saturn. The role of planets orbital eccentricity, their true anomaly, and mass ratios is investigated. Moreover, the influence of the post-capture orbit in terms of inclination and orientation is also assessed. Analyses are performed from qualitative and quantitative perspective. The quality of capture orbits is measured by means of the stability index, whereas the capture ratio gives information on their statistical occurrence. Some underlying principles on the selection of the dynamical model, the initial true anomaly, and inclination are obtained. These provide a reference for practical cases.
► Effects of LSP on mechanical properties of stainless steel ANSI 304 are evaluated. ► LSP can clearly enhance the values of mechanical properties in the shocked region. ► Martensite transformation ...does not take place in the surface layer subjected to LSP. ► Enhancement mechanisms of LSP on mechanical property of stainless steel are revealed. ► The results can provide some insights on the surface modification of stainless steel.
The aim of this article is to address the effects of a single laser shock processing (LSP) impact on the nano-hardness, elastic modulus, residual stress and phase transformation of ANSI 304 austenitic stainless steel. Residual stress distribution of the LSP-shocked region is determined by X-ray diffraction (XRD) with sin
2
ψ method, and the micro-structural features in the near-surface layer are characterized by using cross-sectional optical microscopy (OM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). By comparing with the untreated samples, LSP can clearly improve nano-hardness, elastic modulus, and residual stress in the LSP-shocked region. The underlying enhancement mechanisms of LSP on nano-hardness, elastic modulus and residual stress of stainless steel ANSI 304 are also revealed. These studies may provide some important insights into surface modification for metal materials.
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► LSP can generate high-level compressive residual stresses and refine original grains. ► Massive LSP impacts can effectively prevent the SCC initiation of the U-bend sample. ► ...Mechanism of massive LSP impacts on SCC was also entirely revealed.
The effects of massive laser peening (LP) impacts on surface residual stress, micro-structure, and stress corrosion cracking (SCC) behaviour of U-bend samples were investigated by X-ray diffraction (XRD) technology, optical microscope (OM) and transmission electron microscope (TEM) observations. Two important factors to influence SCC initiation, residual stress and grain refinement, were discussed in detail by using different types of treatment processes. Results showed massive LP impacts can induce both deep compressive residual stress and refined grains in the surface layer of ANSI 304 stainless steel, and the corrosion mechanism of massive LP impacts on SCC was also analysed and revealed.
Abstract Diabetic cognitive dysfunction (DCD), usually accompanied with chronically elevated glucocorticoids and hippocampal astrocytic alterations, is one of the most serious complications in ...patients with type-1 diabetes. However, the role for chronically elevated glucocorticoids and hippocampal astrocytic activations in DCD remains to be elucidated, and it is not clear whether astrocytic N-myc downstream-regulated gene 2 (NDRG2, involved in cell differentiation and development) participated in DCD. In the present study, three months after streptozotocin (STZ)-induced type-1 diabetes onset, rats showed cognitive impairments in Morris water maze test as well as elevated corticosterone level. Diabetic rats also presented down-regulation of glial fibrillary acidic protein (GFAP, a key indicator of astrocytic reactivity) and NDRG2 in hippocampus revealed by immunohistochemistry staining, real-time PCR and Western blot. Moreover, the diabetic cognitive impairments were ameliorated by 9-day glucocorticoids receptor (GR) blockade with RU486, and the down-regulation of hippocampal NDRG2 and GFAP in diabetic animals was also attenuated by 9-day GR blockade. These results suggest that glucocorticoids-GR system is crucial for DCD, and that astrocytic reactivity and NDRG2 are involved in these processes. Thus, inhibiting GR activation in the hippocampus may be a novel therapeutic strategy for treating DCD.
Functional gradient material (FGM) is an innovative material possessing gradient properties using different premixed proportions of two or multiple metallic powders. In the present work, novel FGMs ...of Ti6Al4V/316L composites with different premixed proportions were successfully fabricated by laser melting deposition (LMD). The microstructure and phase evolution were characterized by means of optical microscopy (OM), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Subsequently, the effects of different Ti6Al4V/316L proportions on micro-hardness, tensile and wear properties were systematically investigated. The results showed that the grain refinement process had experienced three following stages of cellular crystal, columnar crystal and equiaxed crystal with increasing the 316L content. Finally, the LMD-processed FGM specimen with a premixed proportion, 85 wt % Ti6Al4V/15 wt % 316L, is achieved, and exhibits the optimal wear resistance.
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•Effects of phase transformation on the microstructure were investigated.•The tensile properties of specimens with different powder mixture were discussed.•Effects of different content of 316L on wear resistance were revealed.•Relationship between the content of 316L and micro-hardness was characterized.•The specimen with best mechanical properties was achieved.
Anticancer chemotherapeutics are effective weapons for cancer therapy, but the continuous emergency of multidrug-resistant cancer and the side effects of current available anticancer ...chemotherapeutics are the major obstacles in the control and eradication of cancers. Pyrrolo2,3-
d
pyrimidines could inhibit signal transduction cascades affecting cell proliferation, migration, and angiogenesis, representing privileged scaffolds for the discovery of novel anticancer candidates. This review highlighted the recent developments of pyrrolo2,3-
d
pyrimidines with anticancer potential and discussed mechanisms of action, covering papers published from 2018 to present, to facilitate further rational design of more effective candidates.
Massive laser shock peening (LSP) impacts have been a competitive alternative technology to improve fatigue life, corrosion and wear resistance of metallic component which depend strongly on the ...generated surface profile and plastic deformation in the surface layer. First, a three-dimensional finite element modeling (FEM) model with different overlapping rates has been developed to predict residual stress distribution and surface profile of LY2 Al alloy. Second, residual stress distribution predicted is validated by experimental data. Next, four kinds of overlapping rates, 30%, 50%, 70%, and 90%, are chosen to investigate the uniformity and affected depth of residual stress. Special emphasis is also placed on the effects of overlapping rate on surface profile and plastic deformation of LY2 AL alloy subjected to massive LSP impacts. Finally, the underlying influence mechanism of overlapping rate on surface profile of LY2 Al alloy is also clearly revealed.
•Residual stress field of LY2 Al alloy as a function of overlapping rate is analyzed.•Fluctuation value of plastic deformation decreases as overlapping rate increases.•Underlying influence mechanism of overlapping rate on surface profile is clearly revealed.
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