[en] The structural analysis of the following compound was performed: Ga_1_3(enH_2)_1_,_5(OH)_2_4(NO_3)_1_8•(H_2O)_3_6 (R-3, a=b=19.993 (3); c=18.493 (4) Å; V=6401.7 (2) Å T=153(2)K, Z=3; D_c_o_m=2.48g/cm"3, μ(CuKα)=4.207mm"-"1). Its structural formula was established: ⎢Ga_1_3(μ-OH)_2_4(OH_2)_2_4⎥(enH_2)_1_,_5(NO_3)_1_8•12H_2O. The obtained 13-cyclic cation by its geometric dimensions can be related to nanoclusters. (author)

[en] We studied the special roles of loose neutron-halo structure of ¹⁹B on the fragmentation and momentum dissipation by using isospin dependent quantum molecular dynamics. In order to protrude the special roles of neutron-halo structure on the reaction dynamics we compared the fragmentation multiplicity and nuclear stopping (momentum dissipations) induced by neutron-halo nucleus ¹⁹B with those induced by a same mass stable nucleus ¹⁹F under the same incident channel condition. We found that the loose neutron-halo structure of ¹⁹B increases the fragmentation multiplicity in lower beam energy region. On the contrary, the special halo structure of ¹⁹B weakens the nuclear stopping, compared to those induced by stable nucleus ¹⁹F. However both fragmentation multiplicity-difference and nuclear stopping-difference between the reactions induced by ¹⁹B and ¹⁹F gradually decrease and finally disappear as the increase of beam energy. These results suggest a good project for the experimental measurements of the fragmentation multiplicity and nuclear stopping to study the reaction dynamics induced by neutron-halo nuclei

[en] Highlights: • Internal friction on a Ni–Ti-Hf High-Temperature Shape Memory Alloys. • Martensitic transformation on a Ni–Ti-Hf High-Temperature Shape Memory Alloys. • Anomalous pre-martensitic softening measured on a Ni–Ti-Hf Shape Memory Alloy. • Mechanical Spectroscopy allows measuring the Clausius-Clapeyron coefficient. -- Abstract: The martensitic transformation of Ni_49.5Ti_35.5Hf₁₅ high temperature shape memory alloy is characterized by internal friction measurements. The temperatures for the reversible B2 ↔ B19’ transformation appear in the range 410–479 K on cooling and 447–526 K on heating. In addition, a strong anomalous pre-martensitic softening of the dynamic modulus is reported in the high-temperature phase, between 850 K and 550 K, evidencing the thermoelastic character of this family of alloys. Based on the analysis of the internal friction spectra, a theoretical and experimental methodology is proposed to measure the Clausius-Clapeyron coefficient through mechanical spectroscopy. This new non-destructive method could be extremely useful for the development of advanced prototypes of shape memory alloys.

[en] An antiphase boundary (APB)-like structure of the B19' martensite in Ti-Ni alloy was investigated by transmission electron microscopy. The APB-like structure shows atomic shifts on both the (0 1 0)_B19' plane along the c-axis and the (0 0 1)_B19' plane along the b-axis; a kind of ledge-and-step structure on the b-c plane, in addition to a displacement along the a-axis. The displacement vector can be expressed as R = <-0.1648 1/2 0.4328> in terms of the conventional atomic coordinates of Ti and Ni in the B19' martensite. The APB-like structure is not inherited from APB in the B2 parent phase. We conclude that the APB-like structure is developed by accidental impingement of differently nucleated martensitic domains during the transformation. This structure is defined as a kind of stacking fault with an APB-like contrast.

[en] Highlights: • Metastable CuZr B19’ structure can be stabilized by external pressure of 0.87 Gpa in DFT structural relaxation. • Reversible phase transition exists between phases B19’ and B33. • Thermodynamic and mechanical performances of B33 phase are generally superior than B19’ phase. -- Abstract: The stress-induced martensitic transformation of CuZr-based alloy takes an indispensable part in its shape memory effect and plasticity improving. CuZr–B19’ phase as an unstable martensite product of CuZr–B2 austenite has been widely reported by experimental and DFT methods. However, the instability of B19’ structure ignored in theoretical calculation drives it transform into B33 phase after structural relaxation, which makes computational properties of B19’ phase untrusted. Therefore, in this work, we prevented B19’ phase from relaxation phase transition by applying external force to supply a reliable structure for its subsequent properties calculations. In addition, a reversible phase transition between phases B19’ and B33 was found and the theoretical value of transformation stress was determined. The changes of elastic modulus, formation enthalpy and electronic property of two phases (B33 and B19’) under various pressures were compared and analyzed. The results aforementioned justify that CuZr–B33 is an indirect martensite product of CuZr–B2 phase, which explains why some peoples observed B33 phase in experiments, while others did not.

[en] Highlights: • The consolidated Ti–Ni alloys were successfully prepared at optimized sintering temperature. • Ti₂Ni phase distributed regularly and formed a network structure in sintered Ti–Ni alloys. • The Ti–Ni alloys were featured with single stage B2⇌B19′ martensitic transformation. • The sintered Ti–Ni alloys through hot-pressed sintering possessed the higher strength. -- Abstract: High strength Ti–Ni shape memory alloy had been manufactured by hot-pressed sintering of Ti–Ni alloy powders. Due to the higher temperature sintering and assisted with the external pressure of 80 MPa, the higher density of Ti–Ni alloys can be obtained. The Ti–Ni alloy sintered at the appropriate sintering temperature was characterized by the network structure formed by the Ti₂Ni phase distributing along the surface of original alloy powders. Merely one-stage B2⇌B19′ martensitic transformation was observed in the consolidated Ti–Ni alloy due to the homogeneous chemical composition, irrespective of the sintering temperature. The martensitic transformation temperature slightly changed, which was largely related to the number and distribution of Ti₂Ni phase, as the sintering temperature increased. The mechanical properties of present Ti–Ni alloy were enhanced with the increased sintering temperature. Moreover, the outstanding strain recovery characteristics with the recoverable strain of 8.13% at the pre-strain of 10% condition can be achieved in Ti–Ni alloy prepared at the temperature of 1000 °C, which was attributed to the higher yield stress and weaker hamper effect of Ti₂Ni phase on the movement of martensitic interface.

[en] Transformation behavior, shape memory characteristics and superelasticity of a Ti-43.0Ni-5.0Cu-2.0Fe (at.%) alloy were investigated by means of differential scanning calorimetry, X-ray diffraction, thermal cycling tests under constant load and tensile tests. The alloy transformed in three stages i.e., B2-R-B19-B19'. The maximum recoverable elongation of the R-B19 transformation was 2.3%

[en] We reported the fatigue cracking characteristics of a special copper bicrystal with a tilt Σ 19b grain boundary (GB) and a coplanar primary slip system between the two grains. It is found that the primary slip bands of the two adjacent grains have a good continuation across the GB on the four surfaces of the bicrystal specimen in the axial plastic strain range of 1.5x10^-4-2.13x10^-3. It indicates that the surface slip bands had transferred through the GB during cyclic deformation. When cyclic plastic strain was continued to be applied on the bicrystal specimens, fatigue cracks always initiated and propagated along the GB at all the applied strain amplitudes. By using electron channeling contrast (ECC) technique in scanning electron microscopy (SEM), the dislocation patterns near the GB of the bicrystal were observed. The ladder-like persistent slip bands (PSBs) did not transfer through the GB continuously, no matter what the surface or the common primary slip plane of the bicrystal. Instead, a dislocation affected zone (DAZ) or piling-up of dislocations near the GB was observed. Based on the results above, the fatigue cracking mechanism of the bicrystal was discussed and the GB cracking was attributed to the difference in the slip directions of the two adjacent grains

[en] The glycosphingolipid globoside (globotetraosylceramide, Gb4Cer) has been proposed to be the cellular receptor of human parvovirus B19. Quantitative measurements of the binding of parvovirus B19 to Gb4Cer were performed to explore the molecular basis of the virus tropism. Solid-phase assays with fluorescence-labeled liposomes or ¹²⁵iodine-labeled empty capsids were used to characterize the specificity of binding. In addition, surface plasmon resonance on lipid layers, as well as isothermal titration microcalorimetry, was utilized for real-time analysis of the virus-receptor interaction. These studies did not confirm binding of Gb4Cer to recombinant B19 VP2 capsids, suggesting that Gb4Cer does not function on its own as the cellular receptor of human parvovirus B19, but might be involved in a more complex recognition event. The biochemical results were further confirmed by cryo-electron microscopy image reconstructions at 10 A resolution, in which the structures of empty capsids were compared with empty capsids incubated with Gb4Cer

[en] The most neutron-rich boron isotopes ²⁰B and ²¹B have been observed for the first time following proton removal from ²²N and ²²C at energies around 230 MeV/nucleon. Both nuclei were found to exist as resonances which were detected through their decay into ¹⁹B and one or two neutrons. Two-proton removal from ²²N populated a prominent resonance like structure in ²⁰B at around 2.5 MeV above the one-neutron decay threshold, which is interpreted as arising from the closely spaced 1^-,2^- ground-state doublet predicted by the shell model. In the case of proton removal from ²²C, the ¹⁹B plus one-and two-neutron channels were consistent with the population of a resonance in ²¹B 2.47 ± 0.19 MeV above the two-neutron decay threshold, which is found to exhibit direct two-neutron decay. The ground-state mass excesses determined for ^20,21B are found to be in agreement with mass surface extrapolations derived within the latest atomic-mass evaluations. (authors)