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To evaluate the clinical characteristics, biochemical parameters and the distribution of HLA-DQ genotypes among adult patients with celiac disease (CD) in Northwest China.This cross-sectional study retrospectively collected clinical, biochemical, and HLA-DQ genotype of patients with CD from a tertiary hospital in Xinjiang Uygur Autonomous Region, China between March 2016 and December 2021. Small intestinal biopsy and serum-specific antibodies were used to diagnose CD.Of the 102 CD patients, 63.7% were women (female: male = 1.76:1), and the mean age was 47.3 ± 14.7 years at diagnosis. Common gastrointestinal symptoms included abdominal pain (50.0%), diarrhea (39.2%), and abdominal distension (24.5%). While common extraintestinal manifestations were anemia (48.0%), osteopenia or osteoporosis (36.3%), and fatigue (35.3%). Approximately 34.3% of patients with CD had comorbidities, with the most common being thyroid diseases (18.6%). Biochemical profiles showed lower hemoglobin, higher platelet count, and 25-hydroxyvitamin D (25[OH]D) deficiency. HLA-DQ2/DQ8 was detected among all 53 patients who underwent genotype testing; the frequency of the HLA-DQ2.5, DQ2.2, and DQ8 haplotypes was 71.7%, 24.5%, and 3.8%, respectively.CD was more common among women. Clinical manifestations include primarily gastrointestinal symptoms, but extraintestinal manifestations were not uncommon. Lower hemoglobin level, higher platelet count, and 25[OH]D deficiency are the main biochemical manifestations. The HLA-DQ2.5 and DQ2.2 haplotypes are the most common genotypes in CD.

Carbon nanocomposites with Ru-doped Fe2O3 nanoparticles are derived from a Fe–Ru–Fe trinuclear complex and zeolitic imidazolate framework 8 and exhibit excellent electrocatalytic activity towards oxygen reduction reaction, comparable to that of Pt/C.

Mechanical responses of tungsten (W) and its alloys are strongly controlled by the properties of 1/2 screw dislocations. Rhenium (Re), as a typical alloying and transmutation element in W, can substantially modify the properties of the dislocations, thus the plasticity of the materials. In this study, we investigate the interaction of Re and Re clusters with the screw dislocations in W by first-principles calculations in combination with theoretical models. Specifically, we propose two competing and Re-distribution dependent mechanisms, i.e. “ductilizing effect” and “hardening effect”; both are crucial to the mechanical properties of W. For the ductilizing effect, dispersed Re atoms weaken the surrounding interatomic interaction and reduce the shear resistance, thus facilitating the motion of the dislocation. In contrast, for the hardening effect, Re clusters formed by aggregated Re atoms due to irradiation can increase the Peierls stress and energy, thus hindering the motion of the dislocations. The proposed mechanisms shed light on the experimental observations that there is a Re-induced transition from ductilizing to hardening due to irradiation. The current work provides a theoretical guidance to the development of W-based future fusion materials in search of ductilizing alloying elements.

By performing the first-principles calculations, we explore the dissolution and diffusion of hydrogen (H) in hexagonal closed packed zirconium (Zr) as well as its interaction with vacancy. We show that the tetrahedral (TE) interstitial site is the favorable trapping site for a single H atom with the solution energy of −0.45 eV. Such a negative solution energy is due to the strong electronic bond between H and neighboring Zr atoms. Moreover, the energy barrier for the migration of H from a TE site to its 1NN and 2NN TE site is 0.12 eV and 0.42 eV, respectively. It is noteworthy that the first path only slightly contributes to the experimentally measured H diffusivity in Zr, because the H atom is trapped by two nearest neighboring TE sites. Thus, the effective activation energy for H diffusion in Zr should be mainly determined by the second path, and the corresponding energy barrier is 0.42 eV. Furthermore, since the electronic density (available volume) in vacancy is lower (larger) than that of interstitial site, vacancy is a strong trap for H atoms in Zr. We demonstrate that the maximum of 8 H atoms can be accommodated in a mono-vacancy without the observation of H2 molecule. These results can provide a basis to develop Zr materials in nuclear cladding devices.

High-energy collision cascades with an energy of up to 300 keV for the primary knock-on atom (PKA) have been initially simulated in W and W–Re alloys containing 5 or 10 at.% Re atoms using the molecular dynamics method with recently fitted W–Re interatomic potentials. The effects of PKA energy and Re concentration on defect production, defect clustering and states of dislocation loops have been quantitatively analysed. The results show that the presence of Re atoms does not significantly affect either the number of surviving defects or their clustered fractions. In addition, the interstitial dislocation loops are dominated by the 1/2 loops. Mixed interstitial loops with 1/2 and Burgers vectors and interstitial loops that have the same Burgers vectors but are located on different habit planes have also been observed. Further analysis indicates that the pinning effect induced by the Re atom segregation leads to the lower mobility of the interstitial clusters and interstitial 1/2 loops in W–Re alloys than in pure W, which is expected to influence the subsequent evolution of radiation-induced defects in W–Re alloy.

We have investigated the dissolution, diffusion, and retention of hydrogen (H) in tungsten-rhenium (W-Re) sigma (σ) phase using a first-principles method and thermodynamic models, in order to explore the influence of Re-rich precipitation on H behaviors in W. Taking the most stable W-Re σ phase (W-33.3 at.% Re) as an example, it is found that the solution energy of H at most interstitial sites (>80%) in W-Re σ phase is much lower than that in pure W. Specifically, the H solution energy at most stable interstitial site in W-Re σ phase is only 0.47 eV, ~54% lower than that in pure W. This can be attributed to that W-Re σ phase provides the larger available volume for interstitial H than the pure W, weakening the W-H repulsive interaction. Moreover, it has been demonstrated that this trend is almost independent on the Re concentration in W-Re σ phase. We have further determined the interaction between H atoms and mono-vacancy in W-Re σ phase based on the calculation of H trapping energies and the Polanyi-Wigner equation. The W-type and Re-type vacancy can accommodate 10 and 5 H atoms at room temperature (RT) in σ phase, respectively, and thus the average trapping capability of vacancy for H in σ phase is stronger than that in pure W (~6 H atoms at RT). Consequently, our calculations reveal that the Re-rich precipitation (both interstitial and vacancy sites) can serve as the strong trapping centers for H in W, significantly enhancing the H retention, which is entirely different from the negative effect of dispersed-Re/small Re clusters.

Tungsten (W) and W-based alloys are the leading candidates for plasma-facing materials (PFMs) in future fusion reactors. However, the high energy neutrons generated in fusion reactions not only result in cascade damages but also cause W transmutation. Both the irradiation defects and transmutation products, mainly rhenium (Re), have serious effects on the service behaviors of W PFMs. In this work, we have systematically investigated the interaction between Re and the self-interstitial atoms, self-interstitial clusters and 1/2 interstitial dislocation loops in bulk W using molecular dynamics and statics simulations. It is found that there is a strong attractive interaction between an interstitial W atom and a substitutional Re atom, forming a Re–W dumbbell that migrates 3-dimentionally due to the low migration and rotation energies. The small SIA clusters strongly bind with both the substitutional Re atoms and an interstitial Re atom (Re–W mixed dumbbell), thus decreasing the mobility of these clusters. The strong attractive interaction between a Re atom and a 1/2 interstitial dislocation loop occurs when the Re atom is located at the core of the loop, and also, their interaction distance along direction is large. The mobility of the 1/2 interstitial dislocation loop decreases progressively with increasing Re concentration.

Here, we review recent computational findings focused on the behavior of transmutation elements (TEs) in Tungsten (W). W is chosen as one of the most promising materials for the divertor armor and plasma facing components in future fusion reactors. However, W in exposure of fusion neutrons can cause the transmutation reaction and produce TEs, such as rhenium and osmium. The presence of TEs can change chemical component of materials, and therefore inevitably influence the microstructure and properties of W materials. Multiscale simulation methods have been employed to investigate the dissolution, diffusion and radiation induced precipitation of TEs, as well as their effects on the behaviors of hydrogen isotopes in W. This systematic review can provide an insightful understanding to estimate the influence of TEs on the properties and performance of W-based materials. Keywords: Tungsten, Transmutation elements, Radiation induced precipitation, Point defects, Hydrogen

We investigate the effects of the hydrostatic strain on the dissolution, diffusion, and clustering of alloying/transmutation elements rhenium (Re) and osmium (Os) in tungsten (W) by using the first-principles method in combination with thermodynamic models. Results show that the strain has significant influences on the dissolution/diffusion of Re/Os as well as their interactions with defects, and thus enhances the clustering of Re/Os in W. For defect-free case, the tensile strain can enhance the clustering of Re/Os in W, while the compressive one can inhibit the formation of Re/Os clusters. Specifically, the energy barrier of Os nucleation in W under 5% tensile (compressive) strain is 0.52 eV (2.32 eV), which is 66% lower (53% higher) than that in strain-free W, suggesting that the tensile/compressive strain has a prominent effect on the clustering of Os in W. Further, the tensile strain can improve the stability of multi Re/Os complexes with SIA and reduce the vacancy-mediated diffusion energy barrier of Re/Os, indicating that the tensile strain can also facilitate the clustering of Re/Os in W with defects. Based on our calculated results, we thus propose a strain-triggered cascading effect of Re/Os clustering in W, i.e., the dissolution and accumulation of Re/Os induce a tensile strain in W lattice surrounding the Re/Os atoms, which in turn further facilitates the clustering of Re/Os in W.

Seeding the impurity elements in W can affect the H behaviors. The effect of Ne on H behaviors in W bulk and W (110) surface has been investigated with the first-principles density functional theory (DFT) calculations in the present paper. It is found that the interactions between the interstitial Ne and H are attractive in bulk W. Ne atom can reduce the binding energies for H in the vacancy and divacancy, and the binding energies decrease linearly with the ratio of Ne and vacancy. In the W (110) surface without vacancy, the threefold hollow site is the most preferable site for H adsorption; Ne atom cannot be adsorbed on the W surface and in the subsurface because of the weak interaction. The substitutional Ne in subsurface can impede H absorption, and increase the diffusion barrier for H from the surface into subsurface.

Dislocation, playing a crucial role in the plastic deformation of metals, can be significantly affected by introducing solute elements. Hydrogen (H) embrittlement is one such example, while the underlying mechanism for H affected dislocation structural stability and mobility remains unclear and the role of H has been controversial. Here, using first-principles calculations, we demonstrate that the effect of H on screw dislocation in bcc metals is H concentration-dependent, signified by a H-induced transition of SD core structure. At low concentrations of H segregation, dislocation maintains the intrinsic easy-core structure, and H atoms are attached to the "periphery" of dislocation to enhance dislocation motion. In contrast, at high H concentrations, dislocation transforms into a hard-core, metal hydride-like structure, as H atoms become the "body" of dislocation to significantly reduce the dislocation mobility. Further, such local easy-to-hard transition is found to be induced by just one solute of other elements, including helium, carbon, nitrogen and oxygen, independent of solute concentration. Our work sheds new light on the H-dislocation interactions in bcc metals, having broad implications in the interstitial solute-related phenomena.

Carbonate rocks are widely distributed in the Tarim Basin. There are mainly three types: subsalt dolomite, buried-hill dissolution carbonate rocks, and fracture-cavity dissolution carbonate rocks. The fracture-cavity dissolution carbonate rock is the most complicated one. Early exploration and development were mainly targeted at large caves with low accuracy requirements. While the current stage of fine development requires more accuracy and focuses on a small fracture-cavity reservoir, even a horizontal or vertical deviation around ten meters may cause drilling failure and bring huge economic losses. This paper has proposed an efficient method for optimizing drilling track based on vertical seismic profile (VSP) data. Performing VSP logging right after drilling to the target layer can get accurate geological stratification to rapidly update the structural model. Besides, more accurate formation velocity, Q value, and anisotropic parameter fields are obtained from VSP seismic acquisition to achieve anisotropic depth migration processing and get high-quality seismic data. Finally, the target location is predicted through a more precise reservoir prediction and well trajectory is optimized to enter the target. This technology has applied in the desert hinterland of Tabei area and achieved satisfying result, it not only improved the quality of seismic data but also promoted the reservoir encounter rate, which reduces the cost of the development scheme.

The aim of this study was to generate periodic microstructures on pure titanium surface by femtosecond laser-etching after sandblasting, and to assess the physicochemical properties of its surface.Twelve pure titanium discs with diameter of 10 mm and thickness of 4 mm were used and divided into 3 groups according to different surface treatment methods: group S (sandblasting surface), group SA (sandblasting surface with acid-etching), and group SL (sandblasting surface with femtosecond laser-etching). Scanning electron microscopy (SEM) was used to observe the surface morphology. X-ray energy spectrum(EDS) was used to observe the surface chemical compositions. Three dimensional surface topography and surface roughness were evaluated by laser scanning confocal microscope (CLSM). The static contact angle was detected by high temperature wetting angle measuring instrument. SPSS19.0 software package was used for statistical analysis.SEM and CLSM showed well-distributed periodic and cyclic microstructure which formed second-order roughness composite structure in group SL. EDS analysis showed that the Al element on SL surface decreased (group SL 4.37%group S 5.18%group SA 7.27%), and the ratio of O/Ti increased (group SL 1.74group SA 0.32group S 0). Surface roughness analysis showed that surface roughness significantly increased in group SL [group SL (7.33±0.38)μmgroup SA (1.08±0.12)μmgroup S (1.05±0.14)μm](P0.001). Static contact angle analysis showed that the static contact angle of surface was significantly reduced in group SL [group SL (34.4±2.5)°group SA (65.0±2.9)°group S (83.7±2.6)°] (P0.001).Sandblasting combined with femtosecond laser-etching of pure titanium surface has excellent surface physicochemical properties and is a promising surface modification technology for titanium implant.

Using a first-principles method in combination with thermodynamic models, we investigate the interaction between rhenium/osmium (Re/Os) and defects to explore the mechanism of radiation-induced Re/Os precipitation in tungsten (W). We demonstrate that radiation-induced defects play a key role in the solute precipitation in W, especially for self-interstitial atoms (SIAs). The presence of SIAs can significantly reduce the total nucleation free energy change of Re/Os, and thus facilitate the nucleation of Re/Os in W. Further, SIA is shown to be easily trapped by Re/Os once overcoming a low energy barrier, forming a W-Re/Os mixed dumbbell. Such W-Re/Os dumbbell forms a high stable Re/Os-Re/Os dumbbell structure with the substitutional Re/Os atoms, which can serve as a trapping centre for subsequent interstitial-Re/Os, leading to the growth of Re/Os-rich clusters. Consequently, an interstitial-mediated migration and aggregation mechanism for Re/Os precipitation in W has been proposed. Our results reveale that the alloying elements-defects interaction has significantly effect on their behaviors under irradiation, which should be considered in the design of W-based alloys for future fusion devices.

Tungsten (W) and W-based alloys have been considered as promising candidates for plasma-facing materials (PFMs) in future fusion reactors. The formation of rhenium (Re)-rich clusters and intermetallic phases due to high energy neutron irradiation and transmutations significantly induces the hardening and embrittlement of W. In order to better understand these phenomena, in the present work, new interatomic potentials of W-W, Re-Re and W-Re, suitable for description of radiation defects in such alloys, have been developed. The fitted potentials not only reproduce the results of the formation energy, binding energy and migration energy of various radiation defects and the physical properties from the extended database obtained from DFT calculations, but also predict well the relative stability of different interstitial dislocation loops in W, as reported in experiments. These potentials are applicable for describing the evolution of defects in W and W-Re alloys, thus providing a possibility for the detailed understanding of the precipitation mechanism of Re in W under irradiation.

The “void lattice” formed by periodic arrangements of voids, usually replicating the symmetry and crystallographic orientation of the host matrix, is an interesting phenomenon in materials under neutron irradiation. In this work, taking tungsten (W) as an example, we explore the formation mechanism of the void lattice using an object kinetic Monte Carlo (OKMC) model together with the collision cascades simulated by the molecular dynamics method. The entire formation processes from the chaotic neutron irradiation defects to the observable void lattice are reproduced via OKMC simulation, which could be divided into three stages: nucleation, incubation and growth. It is found that both the one-dimensional (1D) migration of SIAs and the fraction of clustered vacancies in cascades play a critical role in the formation of the void lattice. On the one hand, the 1D migration of SIAs leads to the mutual protection of voids aligned in directions. The self-shielded voids may therefore grow faster than the unaligned ones. On the other hand, a moderate fraction of clustered vacancies in cascades guarantees the stable nucleation and growth rates of voids. Once the density of the aligned voids reaches a critical value, the shrinkage rate of the unaligned voids will overwhelm their growth rate, leading to the formation of void-free channels and thus the void lattice. Our results reveal the synergistic effects of the fraction of clustered vacancies in cascades and 1D migration of SIAs for the formation of the void lattice in W under neutron irradiation, which improves the fundamental understanding of the self-assembled microstructures in irradiated materials.

The oxygen (O) induced embrittlement of molybdenum (Mo) grain boundary (GB) is one of the key issues that limit the application of Mo-based alloys. The addition of carbon (C) can suppress the O-induced embrittlement. In this study, taking Σ5 (3 1 0)/[0 0 1] Mo GB as an example, we investigate the segregation of C/O into Mo GB and their influences on GB properties by using the first-principles method. It has been demonstrated that the suppressing effect of C on O-induced embrittlement should be mainly attributed to C inhibiting the O segregation in Mo GB, while the direct strengthening effect of C cannot compensate for the reduction of fracture energy induced by O. On the one hand, due to the attractive interaction between C and O, the presence of C effectively reduces the mobility of O in bulk Mo, thereby slowing down the segregation of O. On the other hand, owing to the large available volume and promoted electronic states in the GB region, the segregation of C and O in Mo GB is energetically favorable. Specifically, the interaction of C with O in Mo GB changes to be repulsive from the attraction of C-O in bulk system, suggesting that the pre-segregated C atoms inhibit the segregation of O into GB. This should be rationalized by the site-dependent segregation of O and strong electronic repulsion of C-O pair in the GB region. Consequently, the C addition can effectively reduce the O concentration in Mo GBs and thus relieve the O-induced embrittlement. Our results deepen the understanding of the impurities effects on the properties of Mo GB, and have a guiding significance on the development of advanced Mo-based materials.

Understanding the evolution of irradiation-induced defects is of critical importance for the performance estimation of nuclear materials under irradiation. Hereby, we systematically investigate the influence of He on the evolution of Frenkel pairs and collision cascades in tungsten (W) via using the object kinetic Monte Carlo (OKMC) method. Our findings suggest that the presence of He has significant effect on the evolution of irradiation-induced defects. On the one hand, the presence of He can facilitate the recombination of vacancies and self-interstitial atoms (SIAs) in W. This can be attributed to the formation of immobile He-SIA complexes, which increases the annihilation probability of vacancies and SIAs. On the other hand, due to the high stability and low mobility of He-vacancy complexes, the growth of large vacancy clusters in W is kinetically suppressed by He addition. Specially, in comparison with the injection of collision cascades and He in sequential way at 1223 K, the average sizes of surviving vacancy clusters in W via simultaneous way are smaller, which is in good agreement with previous experimental observations. These results advocate that the impurity with low concentration has significant effect on the evolution of irradiation-induced defects in materials, and contributes to our understanding of W performance under irradiation.

In this paper, we present an interatomic potential for the ternary W–Ta–He system, which is an extension of our previous W–Ta potential. The new potential parameters for the W–He and Ta–He interactions are determined by fitting the results obtained from first-principles calculations. The formation energies of a single He atom at different sites, the binding energies of He–He and He–Vac (Vac = vacancy) in W/Ta, and the binding energies of a single He atom with a solute Ta atom in W are used as the fitting targets. Then, the binding energies of an additional interstitial He atom to existing HenVacm clusters in W/Ta are calculated, and the results reported correspond with the results from the first-principles. Furthermore, the effects of solute Ta on the diffusion and aggregation of He in bulk W are studied. We observed that small interstitial He atom clusters (NHe ≤ 4) were easy to diffuse in pure W, and their diffusion activation energies were less than 0.3 eV. However, the binding energies between Ta and these clusters were between 0.5 and 0.9 eV, which has a pinning effect on the He cluster diffusion. At high temperature, the solute Ta cannot qualitatively hinder the agglomeration of He atoms, however, due to the pinning effect compared with pure W, solute Ta in W has a certain delay effect on the agglomeration of He atoms in time.

We have investigated the effects of noble gas elements (helium, neon, argon and krypton) on the dissolution and accumulation behavior of hydrogen (H) in tungsten (W) using a first-principles method, as well as the behaviors of themselves. Noble gas atoms energetically prefer to occupy the tetrahedral interstitial site (TIS) in W, as the same of H. The TIS → TIS is their optimal diffusion path, and the diffusion energies increase with the increasing of atomic radius. All of them are energetically favorable clustering by self-trapping. It is found that the presence of the noble gas elements have significant effect on H behavior in W. Both interstitial noble gas atoms and their complex with vacancy can serve as strong trapping centers of H, which can be attributed to the redistribution of electron density and lattice distortion induced by noble gas. Most importantly, we have demonstrated that H trapping capability of noble gas clusters will increase with the increasing of the number of noble gas atoms in both interstitial and vacancy-complex cases. The H trapping energy surrounding the noble gas clusters with four atoms is comparable to that in noble gas-free vacancy. Further, the formation of noble gas clusters is much easier than that of vacancy due to the self-trapping interaction between noble gas atoms (>1 eV for interstitial case and >4 eV for vacancy-complex case), and thus the H trapping centers will rapidly increase after noble gas pre-irradiation/implantation. Consequently, the self-trapping character of noble gas induces their strong trapping effect on H.

Tungsten (W) and W alloys are considered as the most promising candidates for plasma facing materials in future fusion reactor. Grain boundaries (GBs) play an important role in the self-healing of irradiation defects in W. Here, we investigate the stability of point defects [vacancy and self-interstitial atoms (SIA’s)] in a Σ5(3 1 0) [0 0 1] tilt W GB by calculating the energetics using a first-principles method. It is found that both the vacancy and SIA are energetically favorable to locate at neighboring sites of the GB, suggesting the vacancy and SIA can easily segregate to the GB region with the segregation energy of 1.53 eV and 7.5 eV, respectively. This can be attributed to the special atomic configuration and large available space of the GB. The effective interaction distance between the GB and the SIA is ∼6.19 A, which is ∼2 A larger than that of the vacancy-GB, indicating the SIA are more preferable to locate at the GB in comparison with the vacancy. Further, the binding energy of di-vacancies in the W GB are much larger than that in bulk W, suggesting that the vacancy energetically prefers to congregate in the GB.

The recombination of one Frenkel pair in tungsten has been investigated through first-principles simulation. Two different recombination types have been identified: instantaneous and thermally activated. The small recombination barriers for thermally activated recombination cases indicate that recombination can occur easily with a slightly increased temperature. For both of the two recombination types, recombination occurs through the self-interstitial atom moving towards the vacancy. The recombination process can be direct or through replacement sequences, depending on the vertical distance between the vacancy and the 〈1 1 1〉 line of self-interstitial atom pair.

We introduce the concept of electrophobic interaction, analogous to hydrophobic interaction, for describing the behavior of impurity atoms in a metal, a “solvent of electrons”. We demonstrate that there exists a form of electrophobic interaction between impurities with closed electron shell structure, which governs their dissolution behavior in a metal. Using He, Be and Ar as examples, we predict by first-principles calculations that the electrophobic interaction drives He, Be or Ar to form a close-packed cluster with a clustering energy that follows a universal power-law scaling with the number of atoms (N) dissolved in a free electron gas, as well as W or Al lattice, as Ec ∝ (N2/3−N). This new concept unifies the explanation for a series of experimental observations of close-packed inert-gas bubble formation in metals, and significantly advances our fundamental understanding and capacity to predict the solute behavior of impurities in metals, a useful contribution to be considered in future material design of metals for nuclear, metallurgical, and energy applications.

Mechanical responses of tungsten (W) and its alloys are strongly controlled by the properties of 1/2 screw dislocations. Rhenium (Re), as a typical alloying and transmutation element in W, can substantially modify the properties of the dislocations,thus the plasticity of the materials. In this study, we investigate the interaction of Re and Re clusters with the screw dislocations in W by first-principles calculations in combination with theoretical models. Specifically, we propose two competing and Re-distribution dependent mechanisms, i.e., “ductilizing effect” and “hardening effect;” both are crucial to the mechanical properties of W. For the ductilizing effect, dispersed Re atoms weaken the surrounding interatomic interaction and reduce the shear resistance, thus facilitating the motion of the dislocation. In contrast, for the hardening effect, Reclusters formed by aggregated Re atoms due to irradiation can increase the Peierls stress and energy, thus hindering the motion of the dislocations. The proposed mechanisms shed light on the experimental observations that there is a Re-induced transition from ductilizing to hardening due to irradiation. The current work provides a theoretical guidance to the development of W-based future fusion materials in search of ductilizing alloying elements.

International audience; We apply the Object Kinetic Monte Carlo method to simulate the hydrogen (H) clustering behaviour with large vacancy (V) clusters in tungsten. The main advantage of this method is to consider the temperature effects, large V clusters, and long-time evolution. It is thus a very useful tool to study the microstructure evolution of defects in irradiated materials covering from the atomic scale to mesoscale. Simulation results show that the number of trapped H atoms by V and V clusters decreases with the increase of temperature. This is expected because the de-trapping ability of H atoms increases when the temperature is increased. With the correction of the zero-point-energy in calculating binding energies, the present results show that the number of H atoms trapped by monovacancy decreases for all studied temperatures. We also found that the trapping ability of V clusters for H decreases with the increase of the sizes of V clusters, independent on temperature. The H concentration can largely affect the clustering behaviour of HmVn. When the H saturation concentration is reached, the clustering behaviour of HmVn is mainly determined by the sizes of V clusters.

The influence of rhenium (Re) on helium (He) evolution in tungsten (W) with different Re distribution is investigated using the first-principles calculations in combination with thermodynamic models. It is found that the He behaviors in W-Re system are closely related to the Re distribution. For the dispersed distribution of Re in W, it is found that a single Re atom only has slight effect on the behaviors of a He atom due to the weak interaction of Re-He1. Interestingly, with the increasing of He numbers, the binding energy between a single Re and He clusters increases rapidly from 0.03 eV for Re-He1 to 0.72 eV for Re-He4. Such high binding energy indicates the strong attraction of Re with He clusters in W. This can be rationalized by the large lattice distortion induced by He clusters, which reduces the electron density of He-occupied position and leads to the transition of neighboring Re/W atom from a substitutional site to an interstitial site. Because of the strong attraction of Re with He clusters, the Re addition effectively reduce the mobility of He clusters in W. As for the aggregated Re distribution, the He trapping capability of vacancy is weakened by Re clusters. These results are well consistent with the experimental observed suppressing effects of Re on the He-induced morphology in W. Further, based on the He behaviors in W-Re σ phase, we suppose that He will segregate from bulk W to Re-rich precipitates, thus enhancing the formation of He clusters. Consequently, our calculations suggest that the distribution of Re plays a key role on the He behaviors in W, which provides a good reference for the design and development of W-based alloys.

Tungsten (W) is regarded as the most promising candidates for plasma-facing materials (PFMs) in future fusion reactors. However, W will be exposed to high fluxes of helium (He) plasma in a nuclear fusion environment, which will degrade the thermal and mechanical properties of W. We have investigated the behavior of He in W using a first-principles method based on density functional theory. It has demonstrated that the quantitative stress indicator and the qualitative hard-sphere model can be used to characterize the effective volume and the stability of interstitial He in W. The hydrostatic tensile (compressive) strain will enhance (suppress) the dissolution and diffusion of He in W. The existing of He will have negative effect on the ideal strength of W. Vacancies and grain boundaries defects in W can serve as trapping centers for He, because the defects can provide large space for He. He will spontaneously form He clusters at the near surface by self-trapping. The pre-existing impurity/alloying element can significantly reduce the solution energy of He in W due to the electron density redistribution induced by them, such as C and Nb. The results will provide good reference for developing W materials as PFMs. This paper reviews our recent findings regarding the behavior of He in W.

We have investigated the hydrogen–beryllium (H–Be) interaction and the behavior of Be in tungsten (W) in order to explore the influence mechanism of Be on H using a first-principles method. A single Be atom is energetically favorable sitting at the octahedral interstitial site (OIS) instead of the tetrahedral interstitial site (TIS), and prefers to diffuse along the OIS → TIS → OIS path. Interestingly, it has been demonstrated that there is large binding energy between Be atoms in W (>1 eV), leading to them energetically clustering. This can be attributed to the strong Be–W repulsion and the intrinsic electrophobic properties of Be. Further, it is found Be has significant effect on H behavior in W. On the one hand, the interstitial Be atom can enhance the stability of H in W, and thus it can serve as a trapping center for H, due to the redistribution of electron density induced by Be. This will block H diffusing deeper into the bulk, leading to the decrease of H retention in W. On the other hand, the H trapping capability of vacancy will be severely weakened by Be, because Be will provide electrons to vacancy resulting in the increasing of the electron density. Hence, the Be-V complex only can hold 5H atoms, 58.3% less than that of the Be-free vacancy, and there is no H2 molecule formation. This indicates Be could suppress H bubbles formation in W. Consequently, H retention and blistering in W can be suppressed by doping Be.

Objective To study the chemical constituents from the roots of Rubus parvifolius. Methods The chemical constituents were extracted and purified by silica gel column chromatography. NMR spectra were used for structural identification. Results Phytochemical study on the roots of R. parvifolius led to the isolation of one ceramide (1), two anthraquinones (2 and 3), four triterpenoids (4-7), two flavonoids (8 and 9), one fatty acid ester (10), and two sterols (11 and 12). Conclusion Compound 1 is isolated from the plants of family Rosaceae for the first time, and compounds 2-5 are isolated from genus Rubus for the first time. Though R. parvifolius shares the same major chemical types (triterpenoid, flavonoid, and anthraquinone) with those of R. alceaefolius, a substituent of R. parvifolius, their individual constituents are different. In addition, R. parvifolius contains ceramide (1) with high concentration, while caffeoylquinic acid reported in R. alceaefolius has not been found in R. parvifolius. Furthermore, the results from our phytochemical study are consistent with the DNA phylogenic relationship between R. parvifolius and R. alceaefolius (two separated subgenera), suggesting that the substitution of the former species with the latter one in folk medicine might not be suitable.

Long-term glucocorticoid use may result in sustained suppression of one or more secreted components from the hypothalamo-pituitary-adrenal axis, and often results in apoptosis. Yougui Pill (YGP), a 10-component traditional Chinese herbal medicine, has been shown to be clinically effective for glucocorticoid-induced suppression of the hypothalamo-pituitary-adrenal axis. However, the pharmacological and molecular mechanisms remain unclear. We hypothesized that YGP would exert an anti-apoptosis effect on dexamethasone-treated anterior pituitary cells. In vivo experiments showed that YGP significantly reduced the number of apoptotic cells, down-regulated mRNA expression of cytochrome c, caspase-3, and caspase-9, and up-regulated mRNA expression of Bcl-2. These findings suggest that YGP reduced glucocorticoid-induced apoptosis in rat anterior pituitary cells by regulating the mitochondria-mediated apoptosis pathway.

This study aimed to investigate the effect of ore particle size on the bioleaching of Yulong copper ore in the bench-scale columns using the mixed culture of moderately thermophilic microorganisms. Bioleaching experiments were carried out on particle sizes of 5-10, 10-15 and 15-25mm in the same kind of column reactors. In the control test of acid leaching, the column reactor was charged with the middle particle size (10-15mm). The results indicated that copper extraction in the column reactor with particle size of 5-10 mm was highest among the three particle sizes. After 110-days leaching, 89% of copper was leached at 5-10 mm particle size while 57% was extracted at 15-25 mm particle size and 80% at 10-15 mm. Under the same particle size (10-15 mm), copper recovery in the column reactor with inoculation of microorganisms was 25% higher in comparison to the control test of acid leaching, while sulfuric acid consumption was 33% less than that.