Atomic-level structural change in Ni-Ti alloys under martensite and amorphous transformations

The Ni-Ti alloys have been used widely as functional materials, especially for the purpose of superelastic behavior or shape memory effect. It has been believed that martensitic transformation (MT) between crystals plays a major role in the phase transition behavior, but recent experimental observation shows that there also exists stable amorphous structure. Detailed information of the atomic-level change, that is microscopic crystalline rearrangement of Ni-Ti alloys in applied shear deformation is needed. Our study aims at clarifying those atomic mechanisms by using molecular dynamics (MD) simulations. For Ni-Ti alloys, we assess the possibility of the modified version of EAM (MEAM) with parameters for Ni-Ti. We construct MD models to investigate both MT and amorphization in Ni-Ti alloys. We devise a method based on so-called common neighbor analysis (CNA) to effectively detects amorphous atoms, by finding clusters with five-folded symmetry (pentagonal bipyramids). In comparing models with different crystal orientation, when crystalline slip is not easy due to small resolved shear stress, the atoms in initial B2 or B19’ structure tend to be rearranged with rotational motion and transform to amorphous atoms. Besides, there are ”pre-amorphous” structures as a symptom of major and later increase of amorphous atoms

Antidepressants Inhibit P2X4 Receptor Function: a Possible Involvement in Neuropathic Pain Relief

BACKGROUND: Neuropathic pain is characterized by pain hypersensitivity to innocuous stimuli (tactile allodynia) that is nearly always resistant to known treatments such as non-steroidal anti-inflammatory drugs or even opioids. It has been reported that some antidepressants are effective for treating neuropathic pain. However, the underlying molecular mechanisms are not well understood. We have recently demonstrated that blocking P2X(4 )receptors in the spinal cord reverses tactile allodynia after peripheral nerve injury in rats, implying that P2X(4 )receptors are a key molecule in neuropathic pain. We investigated a possible role of antidepressants as inhibitors of P2X(4 )receptors and analysed their analgesic mechanism using an animal model of neuropathic pain. RESULTS: Antidepressants strongly inhibited ATP-mediated Ca(2+ )responses in P2X(4 )receptor-expressing 1321N1 cells, which are known to have no endogenous ATP receptors. Paroxetine exhibited the most powerful inhibition of calcium influx via rat and human P2X(4 )receptors, with IC(50 )values of 2.45 μM and 1.87 μM, respectively. Intrathecal administration of paroxetine produced a striking antiallodynic effect in an animal model of neuropathic pain. Co-administration of WAY100635, ketanserin or ondansetron with paroxetine induced no significant change in the antiallodynic effect of paroxetine. Furthermore, the antiallodynic effect of paroxetine was observed even in rats that had received intrathecal pretreatment with 5,7-dihydroxytryptamine, which dramatically depletes spinal 5-hydroxytryptamine. CONCLUSION: These results suggest that paroxetine acts as a potent analgesic in the spinal cord via a mechanism independent of its inhibitory effect on serotonin transporters. Powerful inhibition on P2X(4 )receptors may underlie the analgesic effect of paroxetine, and it is possible that some antidepressants clinically used in patients with neuropathic pain show antiallodynic effects, at least in part via their inhibitory effects on P2X(4 )receptors

Constructing Machine-learned Interatomic Potentials for Covalent Bonding Materials and MD Analyses of Dislocation and Surface

As machine learning potentials for molecular dynamics (MD) simulations, Spectral Neighbor Analysis Potential (SNAP) and quadratic SNAP (qSNAP) were constructed for silicon (Si) and silicon carbide (SiC). The reproducibility of the basic material properties about perfect crystal, free surface and dislocation cores in Si and 3C-SiC was investigated. The coefficients of SNAP and qSNAP were optimized using liner regression to present energy and force obtained by DFT. In addition, hyperparameters (cutoff length and weights for optimization, here) were determined using genetic algorithm to reproduce elastic moduli obtained by DFT. Lattice constant and elastic moduli of Si crystal by MD using our SNAP or qSNAP agree well with the values of DFT, and they have higher accuracy than those by any empirical potential. Additionally, melting point and specific heat at constant pressure were calculated by MD correctly. Especially in qSNAP of Si, the surface energy of {100} and {111} planes and the reconstructed {100} surface structure were almost reproduced. For 3C-SiC, SNAP reproduces lattice constant and elastic moduli of DFT. Furthermore, edge dislocation cores were generated successfully. However, the potentials we constructed have insufficient reproducibility in the plastic region, so it is necessary to continue development

The increase of plasma galectin-9 in a patient with insulin allergy: a case report

Allergic reaction to insulin is known to be associated with eosinophilia and hyper IgE. Recent report showed that eosinophilia is related with the increased synthesis of galectin-9 (GAL-9) and osteopontin (OPN). Here, we examined plasma levels of GAL-9 and OPN first time in a case of 65-year old patient with insulin allergy. Insulin aspart & insulin aspart 30 mix were given to the patient and an elevation of the eosinophil count (8440/μl, 17.6 fold) and a moderate increase of IgE (501 U/ml, reference range: 10-350 U/ml), eotaxin-3 (168 pg/ml, 2 fold), histamine (0.95 ng/ml, 5.3 fold) were found 33 days later. The plasma levels of GAL-9 and OPN were 22.5 and 1.7 fold higher than the cut-off point, respectively. After one month cessation of insulin therapy, elevations of the eosinophil count (3,480/μl; 7.3 fold), and OPN (1.4 fold) still occurred but the GAL-9 levels became normal. Therefore, we noted the increases of GAL-9 and OPN in plasma for the first time in a patient with insulin allergy and propose that GAL-9 reflects the conditions of allergy more accurately

Treatment with Corticosteroid for Pericardial Effusion in a Patient with Advanced Synchronous Esophageal and Gastric Cancers following Chemoradiotherapy

Severe late toxicity following chemoradiotherapy in esophageal cancer, especially cardiac toxicity, is sometimes difficult to treat and is associated with mortality. However there is little published information with regard to patients with delayed pericardial effusion following chemoradiotherapy and its management. We herein report the case of a 63-year-old man with advanced synchronous esophageal and gastric cancers. This patient presented with pericardial effusion with cardiac tamponade after definitive chemoradiotherapy and was successfully treated with corticosteroid after pericardiocentesis. No instances of pericardial and pleural effusions were observed during the 2-year follow-up period until his death from cancer relapses

Development of a soft X-ray angle-resolved photoemission system applicable to 100 µm crystals

A soft X-ray angle-resolved photoemission system applicable to 100 µm crystals has been developed

Fundamental study on functionality of synthetic sulfides: Evaluation of metal sulfides as solid lubricant

Replacement of exhaustible and harmful resources used as solid lubricants is required for sliding elements such as plain bearings. In particular, the substitution of lead containing in the lead bronze is considered an urgent task. Therefore, in this study, attention was focused on metal sulfides (Cu2S, Cu5FeS4, SnS, TiS2, etc) as a substitute material for lead. After synthesis of sulfide and preparation of sintered body, friction and abrasion test was carried out and applicability as solid lubricant was investigated. The tribological properties of the dry conditions were evaluated by a journal type high speed tester. As a result, the friction coefficient of the bronze specimen without sulfide was about 0.3, whereas the bronze specimen containing sulfide showed a friction coefficient of about 0.1, indicating that the sulfide reduced the frictional resistance. Among them, the specimens containing Cu2S and Cu5FeS4 exhibited a lower friction coefficient. It is considered that this is influenced not only by the effect of hardness but also by film formation by sulfide

Interfacial fracture strength property of micro-scale SiN/Cu components

AbstractThe strength against fracture nucleation from an interface free-edge of silicon-nitride (SiN)/copper (Cu) micro-components is evaluated. A special technique that combines a nano-indenter specimen holder and an environmental transmission electron microscope (E-TEM) is employed. The critical load at the onset of fracture nucleation from a wedge-shaped free-edge (opening angle: 90°) is measured both in a vacuum and in a hydrogen (H2) environment, and the critical stress distribution is evaluated by the finite element method (FEM). It is found that the fracture nucleation is dominated by the near-edge elastic singular stress field that extends about a few tens of nanometers from the edge. The fracture nucleation strength expressed in terms of the stress intensity factor (K) is found to be eminently reduced in a H2 environment

Fundamental study on functionality of synthetic sulfides : Evaluation of metal sulfides as solid lubricant

Replacement of exhaustible and harmful resources used as solid lubricants is required for sliding elements such asplain bearings. In particular, the substitution of lead containing in the lead bronze is considered an urgent task. Therefore, in this study, attention was focused on metal sulfides (Cu2S, Cu5FeS4, SnS, TiS2, etc) as a substitute material for lead. After synthesis of sulfide and preparation of sintered body, friction and abrasion test was carried out and applicability as solid lubricant was investigated. The tribological properties of the dry conditions were evaluated by a journal type high speed tester. As a result, the friction coefficient of the bronze specimen without sulfide was about 0.3, whereas the bronze specimen containing sulfide showed a friction coefficient of about 0.1, indicating that the sulfide reducedthe frictional resistance. Among them, the specimens containing Cu2S and Cu5FeS4 exhibited a lower friction coefficient. It is considered that this is influenced not onlyby the effect of hardness but also by film formation by sulfide