The mechanical properties of Mg97Zn1Y2 extruded alloy, composed of Mg matrix phase and a long-period stacking ordered phase, the so-called LPSO phase, with a volume fraction of approximately 24%, ...were investigated using compression tests at room temperature. The microstructure was varied to a large degree by various heat treatments at high temperatures above 400°C, and the relationship between the microstructure and mechanical properties was clarified. The plastic behavior of the Mg/LPSO two-phase alloy was compared with that of Mg99.2Zn0.2Y0.6 alloy, composed almost Mg-solid-solution phase, and the strengthening mechanisms at work in the Mg97Zn1Y2 extruded alloy are discussed. The existence of the LPSO phase strongly enhanced the refinement of Mg matrix grains during extrusion, which led to a large increase in yield stress through the Hall–Petch relationship. In addition, the LPSO phases, which were aligned along the direction of extrusion in the Mg97Zn1Y2 extruded alloy, acted as hardening phases, being roughly coordinated with the short-fiber reinforcement mechanism.
The crystal structure of a long period stacking-ordered (LPSO) phase newly found in the Mg–Al–Gd ternary system has been investigated by scanning transmission and transmission electron microscopy. ...The LPSO phase in the Mg–Al–Gd system is found to form by stacking structural blocks, each of which consists of six close-packed atomic planes. In each of the structural blocks long-range ordering occurs for the constituent Mg, Al and Gd atoms, with enrichment of Gd atoms occurring in four consecutive planes of the six close-packed atomic planes. The ideal chemical composition of the structural block is determined to be Mg29Al3Gd4 (Mg–8.3 at.% Al–11.1 at.% Gd). However, the stacking of structural blocks is largely disordered. Strictly speaking, the technical term LPSO cannot be used to describe this phase because of the long-range ordering of the constituent atoms in each structural block. The crystal structure of the LPSO phase can thus be crystallographically described as one of the order–disorder structures, and either the C2/m, P3112 or P3212 space group is assigned when the simplest stacking of structural blocks is assumed.
It has recently been found that Mg97Zn1Y2 extruded alloy containing a long-period stacking ordered (LPSO) phase has superior mechanical properties. In this study, the high-temperature deformation ...mechanism of the Mg97Zn1Y2 extruded alloy was examined. Grain-boundary strengthening due to the refined Mg-matrix phase and fiber-like reinforcement due to the LPSO phase dominantly contribute to the strengthening of the alloy at room temperature, and they were confirmed to effectively act even at 200°C. As a result, the extremely high strength of the alloy is maintained up to 200°C, unlike other conventional Mg alloys. At 300°C, however, the yield stress of the Mg97Zn1Y2 alloy largely decreases, and the orientation and the grain size dependence of the yield stress become weak. Increases in the operation frequency of non-basal slip in the Mg-matrix grains weaken the grain-boundary strengthening effect. In addition, the effect of fiber-like reinforcement due to the LPSO phase is also weakened at 300°C because the window of microstructure suitable for inducing this effect becomes significantly narrow at this temperature.
Predictions for Drell–Yan lepton pair production at low dilepton mass and small
x
at the LHC usually have a large scale dependence. This can be decreased by determining an optimal factorization ...scale. In this paper, we reduce this scale by imposing a cutoff in azimuthal angle between the transverse momentum of the leptons, properly taking into account Sudakov effects. This allows one to probe the parton distributions at smaller scales eliminating most of the current theoretical uncertainty.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study, the microstructure and mechanical properties of MgZnY alloy sheets were investigated. Tensile tests at room temperature were performed along the rolling direction of Mg98Zn1Y1-, ...Mg96Zn2Y2-, and Mg94Zn3Y3- alloy sheets and their annealed states (773K for 0.6ks). These alloy sheets exhibited yield strengths of 261, 317, and 380MPa, and elongations of 12, 10, and 6%, respectively. The yield strength of a MgZnY alloy sheet with Zn and Y contents greater than 2at% was higher than 300MPa. The microstructure observations suggested that the alloy sheet strength mainly resulted from (i) the formation of basal texture in the long period stacking ordered (LPSO) phase and (ii) the uniform dispersion of a fine Mg3Zn3Y2 phase. In the annealed state, the yield strength tended to decrease, while the elongation tended to increase. Large elongations of 20% or more were achieved in the Mg98Zn1Y1- and Mg96Zn2Y2 -alloy annealed sheets. The cold workability of the MgZnY alloy sheets and an AZ31-O sheet were evaluated, using a V-bending test at room temperature. Both Mg98Zn1Y1- and Mg96Zn2Y2- annealed sheets could be bent without cracking with a minimum bending radius per thickness of 3.3, which was less than that of the AZ31-O sheet. Texture randomization occurred in the MgZnY alloy annealed sheets owing to re-crystallization of the Mg phase, which was confirmed by electron backscattering diffraction (EBSD) analysis. Large elongations and good cold workability of the MgZnY annealed sheets are presumably attributed to an increase in the randomness of the Mg phase owing to re-crystallization. These results suggested that a Mg alloy sheet of high yield strength or good cold workability could be prepared by controlling the alloy composition and its microstructure in the MgZnY alloy system.
We have identified a novel long-period stacking/order (LPSO) phase in a Mg-Ni-Y alloy, which provides novel LPSO structural features regarding both the stacking/order aspects; the 12R-type stacking ...sequence and the in-plane modulation of approximately 7×(12¯10)hcp with respect to the fundamental hexagonal-closed-packed Mg structure. The ideal 7 M model for the present 12R-type LPSO phase is constructed based on the ordered arrangements of the L12-type Ni6Y8 clusters embedded in the local ABCA stacking layers, resulting in the stoichiometry Mg77Ni9Y12 (Mg78.6Ni9.2Y12.2) that appears to be extremely close to the experimentally determined composition Mg78.4Ni9.0±0.2Y12.6±0.3 (at.%). This in turn suggests the robustness of the solute cluster with a specific ratio (Ni6Y8), emerging the pseudo-binary formation behaviors of the LPSO phase in the Mg ternary alloys.
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•A novel type of the long-period stacking/order structure has been determined.•Combined use of electron diffraction/microscopy and first principles calculations.•12R-type stacking sequence and the in-plane order of approximately 7×(12¯10)hcp.•Robust L12-Ni6Y8 cluster rules the LPSO phase formation as a pseudo-binary system.
This phase II trial evaluated the efficacy of cisplatin and fluorouracil (CF)-based combination neoadjuvant chemotherapy on the outcome of patients with resectable locally advanced esophageal ...squamous cell carcinoma (ESCC). We compared the recurrence-free survival (RFS) associated with CF plus Adriamycin (ACF) with that associated with CF plus docetaxel (DCF) to select an alternative regimen in a new phase III trial investigating the optimal neoadjuvant treatment of patients with ESCC.
Patients with resectable advanced ESCC were randomly assigned to either ACF (Adriamycin 35mg/m2, cisplatin 70mg/m2 i.v. on day 1, fluorouracil 700mg/m2 continuous infusion for 7 days) every 4 weeks or DCF (docetaxel 70mg/m2, cisplatin 70mg/m2 i.v. on day 1, fluorouracil 700mg/m2 continuous infusion for 5 days) every 3 weeks. Surgery was scheduled after completion of two cycles of chemotherapy. The primary end point was RFS, analyzed by the intention-to-treat.
Between October 2011 and October 2013, 162 patients at 10 institutions were enrolled in the study, all of whom were eligible and randomly assigned to the two groups (81 to the ACF group and 81 to the DCF group). The R0 resection rates for the ACF and DCF groups were equivalent (95.9% versus 96.2%, P=0.93). The 2-year RFS and overall survival rates for DCF versus ACF were 64.1% versus 42.9% (hazard ratio 0.53, 95% confidence interval 0.33–0.83, P=0.0057) and 78.6% versus 65.4% (P=0.08), respectively.
Compared with ACF, DCF chemotherapy was associated with prolonged RFS for patients with resectable advanced ESCC. Thus, DCF chemotherapy has potential as a standard neoadjuvant therapy for resectable ESCC.
University Hospital Medical Information Network Clinical Trials Registry of Japan (identification number UMIN000004555/000004616).
A series of structural polytypes formed in an Mg-1 at.%Zn-2 at.%Y alloy has been identified, which are reasonably viewed as long-period stacking derivatives of the hexagonal-close-packed Mg structure ...with alternate AB stacking of the close-packed atomic layers. Atomic-resolution Z-contrast imaging clearly revealed that the structures are long-period chemical-ordered as well as stacking-ordered; unique chemical order along the stacking direction occurs as being synchronized with a local faulted stacking of AB′C′A, where B′ and C′ layers are commonly enriched by Zn/Y atoms.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Background
In veterinary medicine, congenital methemoglobinemia associated with nicotinamide adenine dinucleotide (NADH)‐cytochrome b5 reductase (b5R) deficiency is rare. It has been reported in ...several breeds of dogs, but little information is available about its etiology.
Objectives
To analyze the NADH‐cytochrome b5 reductase gene, CYB5R3, in a Pomeranian dog family with methemoglobinemia suspected to be caused by congenital b5R deficiency.
Animals
Three Pomeranian dogs from a family with methemoglobinemia were analyzed. Five healthy beagles and 5 nonrelated Pomeranian dogs without methemoglobinemia were used as controls.
Methods
Methemoglobin concentration, b5R activity, and reduced glutathione (GSH) concentration were measured, and a turbidity index was used to evaluate Heinz body formation. The CYB5R3 genes of the affected dog and healthy dogs were analyzed by direct sequencing.
Results
Methemoglobin concentrations in erythrocytes of the affected dogs were remarkably higher than those of the control dogs. The b5R activity of the affected dogs was notably lower than that of the control dogs. DNA sequencing indicated that this Pomeranian family carried a CYB5R3 gene missense variant (ATC→CTC at codon 194) that resulted in the replacement of isoleucine (Ile) by leucine (Leu).
Conclusions and Clinical Importance
This dog family had familial congenital methemoglobinemia caused by b5R deficiency, which resulted from a nonsynonymous variant in the CYB5R3 gene. This variation (c.580A>C) led to an amino acid substitution (p.Ile194Leu), and Ile194 was located in the proximal region of the NADH‐binding motif. Our data suggested that this variant in the canine CYB5R3 gene would affect function of the b5R in erythrocytes.
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