[en] Silver ions doping made enhancement of the photocatalytic activity of TiO₂, which was determined by degradation of methyl orange (MO), a probe molecule, in an aqueous solution. X-ray diffraction (XRD) investigation demonstrated that the silver doping changed lattice parameters of TiO₂, which should attribute to the O vacancies produced by the substitutional silver ion at lattice site. On above results, a doping mechanism of silver ions in TiO₂ was also discussed

[en] Highlights: •The reaction pathway of nanostructure clad particles with Ni/Al = 3:1 is from NiAl to Ni₃Al compound. •The size of Ni/Al clad particles plays a key role in the presence of NiAl precipitate. •The rate of reaction of system under thermal loading on local region is more rapid compared to that of system under thermal loading on whole system. •The propagation of reaction front is limited by mass transfer for 3Ni + Al clad particles. -- Abstract: The reaction pathway of nanostructure Ni/Al clad particles with a atomic ratio Ni/Al = 3:1 under thermal loading on a local area is investigated by molecular dynamics simulations. We show a complete reaction pathway and confirm the NiAl compound is an intermediate product in the reaction of 3Ni + Al clad particles. The effect of particle size on the propagation of reaction is considered. For the system with larger particle size, part of the NiAl compound forms the phase of B2-NiAl by nucleation. The presence of NiAl precipitate retards the propagation of reaction. The formation of the NiAl phase is dependent on the temperature below a certain threshold. For longer time, the phase of B2-NiAl gradually transforms into Ni₃Al compound that is the final product of 3Ni + Al clad particles

[en] Fully coupled thermo-mechanical model is used to obtain the true strain components. The sizes of the TMAZ and the SZ are predicted according to the different behaviors of the traced material particles. The strain rate and the temperature histories are used to calculate the Zener-Hollomon parameter and then the grain size in the SZ. Results indicate that the contribution from the temperatures is much more important than the one from the deformations. The strain rates at the advancing side are higher than the ones at the retreating side on the top surface but become symmetrical on the bottom surface. The widths of the TMAZ and the SZ become narrower in smaller shoulder diameter. Smaller shoulder can lead to smaller grain size in the SZ.

[en] Graphical abstract: - Highlights: • Nondestructive covalent CNT functionalization is realized by defect oxidation. • A green oxidant K_2Fe"V"IO_4 is used for CNT oxidation for the first time. • Effective CNT oxidation can be achieved at 60 °C in 3 h. • Oxidized CNTs are obtained in yields of above 100 wt%. • FeO_3, an unusual Fe (VI) specie, is produced when K_2FeO_4 is dissolved in H_2SO_4. - Abstract: Chemical oxidation is still the major approach to the covalent functionalization of carbon nanotubes (CNTs). Theoretically, the defects on CNTs are more reactive than skeletal hexagons and should be preferentially oxidized, but conventional oxidation methods, e.g., HNO_3/H_2SO_4 treatment, have poor reaction selectivity and inevitably consume the C=C bonds in the hexagonal lattices, leading to structural damage, π-electrons loss and weight decrease. In this work, we realized the nondestructive covalent functionalization of CNTs by selective oxidation of the defects. In our method, potassium ferrate K_2Fe"V"IO_4 was employed as an oxidant for CNTs in H_2SO_4 medium. The CNT samples, before and after K_2FeO_4/H_2SO_4 treatment, were characterized with colloid dispersibility, IR, Raman spectroscopy, FESEM and XPS. The results indicated that (i) CNTs could be effectively oxidized by Fe (VI) under mild condition (60 °C, 3 h), and hydrophilic CNTs with abundant surface −COOH groups were produced; and (ii) Fe (VI) oxidation of CNTs followed a defect-specific oxidation process, that is, only the sp"3-hybridized carbon atoms on CNT surface were oxidized while the C=C bonds remained unaffected. This selective/nondestructive oxidation afforded oxidized CNTs in yields of above 100 wt%. This paper shows that K_2FeO_4/H_2SO_4 is an effective, nondestructive and green oxidation system for oxidative functionalization of CNTs and probably other carbon materials as well

[en] We investigate the combined effect of the repulsive vector interaction and the positive electric chemical potential on the chiral phase transition by considering neutral color superconductivity. The chiral condensate, diquark condensate, and quark number densities are solved in both two-flavor and two-plus-one-flavor Nambu-Jona-Lasinio models with the so called Kobayashi-Maskawa-'t Hooft term under the charge-neutrality constraint. We demonstrate that multiple chiral critical-point structures always exist in the Nambu-Jona-Lasinio model within the self-consistent mean-field approximation, and that the number of chiral critical points can vary from zero to four, which is dependent on the magnitudes of vector interaction and the diquark coupling. The difference between the dynamical chemical potentials induced by vector interaction for u and d quarks can effectively reduce the Fermi sphere disparity between the two flavors of diquark pairing. Thus the vector interaction works to significantly suppress the unstable region associated with chromomagnetic instability in the phase of neutral asymmetric homogeneous color superconductivity.

[en] In a multisource thermal model, we analyze the dependence of elliptic flow v_2 on the transverse momentum P_T. The model results are compared with the data of π"-, K_S"0, p, and Λ measured in Pb + Au collisions at top SPS energy, 17.3 GeV. It is found that the azimuthal anisotropy in the evolution process of high-energy collisions is correlated highly to the number of participant nucleons

[en] Four-row star type reciprocating compressor was regarded as a compressor with low vibrations. However, an experiment of the new developed compressor shows serious vibration because of unbalanced force caused by the unique structural arrangement. In this paper, the investigation on the vibration balance approaches of four-row star type reciprocating compressor is carried out. The effects of cylinder arrangement, thermodynamic parameters and additional force on the vibration performance are investigated, which can effectively reduce the vibration and noise of the four-row star type reciprocating compressor and provide an optimization basis for the design of this type of compressor. (paper)

[en] A Flash-ADC data acquisition (DAQ) system has been developed for the drift chamber array designed for the External-Target-Experiment at the Cooling Storage Ring at the Heavy Ion Research Facility, Lanzhou. The simplified readout electronics system has been developed using the Flash-ADC modules and the whole waveform in the sampling window is obtained, with which the time and energy information can be deduced with an offline processing. A digital filter algorithm has been developed to discriminate the noise and the useful signal. With the digital filtering process, the signal to noise ratio (SNR) is increased and a better time and energy resolution can be obtained. (authors)

[en] The relation between the vector-isoscalar and vector-isovector interactions in the two-flavor Nambu-Jona-Lasinio (NJL) model is investigated under the different constraints from QCD. We demonstrate that the flavor-mixing can be induced by the mismatched vector-isoscalar and vector-isovector interactions at finite baryon chemical potential μ and isospin chemical potential μ_I . The effect of this non-anomaly flavor-mixing on the possible separate chiral transitions at nonzero μ_I is studied under the assumption of the effective restoration of U(1)_A symmetry. We find that for the weak isospin asymmetry, the two separate phase boundaries found previously can be converted into one only if the vector-isovector coupling g_v^v is significantly stronger than the vector-isoscalar one g_v^s without the axial anomaly. (authors)

[en] Z₃-QCD is a QCD-like theory with strict center symmetry. We use the Polyakov-loop extended quark meson model (PQM) as a low-energy effective theory of Z₃-QCD to study the RW transitions in different center symmetry breaking patterns. The flavor-dependent imaginary chemical potentials, namely (μ_u, μ_d, μ_s) = iT(θ-2Cπ/3, θ, θ + 2Cπ/3) are adopted, which guarantees the RW periodicity. The traditional and quark improved Polyakov-loop potentials are used, respectively. For N_f = 3 with C ≠ 1, the RW transition occurs at θ = π/3 (mod 2π/3), which gets stronger when C declines from one to zero. When C = 1, the RW transition happens at θ = 2π/3 (mod 2π/3) for N_f = 2 + 1, but θ = π/3 (mod 2π/3) for N_f = 1 + 2. We find that all RW transition endpoints are triple points when C = 1. We confirm that the RW transition becomes weaker and the deconfinement temperature gets lower when taking into account the quark back-reaction effect. However, the modification of the gluon sector due to the quark effect does not change the main conclusions mentioned above. (authors)