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PTFE/Al/W granular composite is a kind of impact-initiated energetic material and may well enhance damage to the impacted targets. To gain insight into response behavior of PTFE/Al/W granular composite under different loadings, the combined approach of experiments and theoretical analyses is used in this paper. More specifically, the combinations of quasi-static compression, dynamic tests, and ballistic impact experiments are conducted. Cylindrical PTFE/Al/W granular composite specimens, with a density of 7.7 g/cm 3 and a diameter of 10 mm, are fabricated by cold press molding, sintering, and cooling. Moreover, a high-speed imaging technique is used to record response process of the specimens in ballistic impact experiments. The experimental and analytical results show that the response behavior of PTFE/Al/W granular composite is significantly influenced by the loading strain rate. When the strain rate is less than 3.6 × 10 3 s - 1 , only mechanical response is observed in the quasi-static compression and dynamic tests. However, when the strain rate is higher than 4 × 10 4 s - 1 , the chemical reaction is found in the ballistic impact experiments. Furthermore, chemical response shows an enhanced trend with increasing of the loading strain rate. [ABSTRACT FROM AUTHOR]

To realize the resource utilization of waste mask fibers (MF), a layer of ZnS nanoparticles was grown on MF by a one-step hydrothermal method, and a MF/ZnS sensor was successfully prepared. This is the first time that resource utilization of MF has been combined with the development of a high-performance gas sensor. The MF/ZnS sensor showed high sensitivity and recoverability to target vapors at room temperature. Compared with ZnS powder loaded on a ceramic substrate, the MF/ZnS composite responses to four analytes have been improved by 8.4~35.2 times. In addition, the time for the MF/ZnS sensor to complete one response–recovery cycle for all four analytes was less than 30 s. This should be attributed to the high gas permeability of the MF substrate, which made the ZnS particles loaded on the MF more fully exposed to contact with the target vapors. This work not only provides a simple and low-cost method to optimize the sensing performance of gas sensors but also provides a new way for the resource utilization of MF. [ABSTRACT FROM AUTHOR]

This paper reports the findings of the experimental and numerical study on the mechanical behaviour of the normal aggregate concrete filled steel tube (NACFST) and the recycled aggregate concrete filled steel tube (RACFST) columns strengthened with carbon fibre reinforced plastic (CFRP) subjected to axial concentric and eccentric loadings. The study was carried out to examine the influence of the tube thickness, the concrete type, the CFRP reinforcement and the load eccentricity on the compressive behaviour of RACFST. Simple finite element models were then developed to simulate the compressive behaviour of both RACFST and NACFST columns, with good correlation to the experimental results in terms of load–displacement traces and deformation modes. The results indicate that both RACFST and NACFST specimens have a similar deformation mode, with the axial compression capacity of RACFST specimens only slightly lower than that of NACFST. The comparisons of the calculations from the standards of American Concrete Institute (ACI), Australian (AS) and Eurocodes (EC4) show that ACI and AS are more conservative than EC4. Furthermore, the modified models are proposed, which provide good predictions of the peak load for the columns strengthened with CFRP under both concentric and eccentric axial loadings, to offer a necessary help to the relevant designs. [ABSTRACT FROM AUTHOR]

A novel method is presented for the production of the 6 + 1 filament MgB2 wires using internal Mg diffusion (IMD) process. For the MgB2 long wire with 1.4-mm diameter produced by graphene-coated Nb addition, the critical current (Ic) is about 1000 A at 4 T and 4.2 K, which is 2.5 times higher than that of the undoped sample. The increased Ic is attributed to the enhanced flux pinning force and improved grain connectivity. The obtained results show that graphene-coated Nb addition MgB2 wires have excellent superconductivity and mechanical property compared with the conventional PIT wires in practical application. [ABSTRACT FROM AUTHOR]

In this work, practical kilometer-length 18- and 30-filament Monel/Nb/MgB2 wires have been prepared by in situ powder-in-tube (PIT) method, combing in the twisting of wires with twisting pitches (TP) of 5 mm, 10 mm, and 20 mm. Transport critical current density (Jc) properties at various temperatures and magnetic fields for MgB2 wires with different TP and the effects of the heat-treatment conditions and wire diameter size on the Jc of 30- filament wire have been investigated in detail. The results suggest the Jc of MgB2 wire without twisting at 4.2 K, 4 T, and 20 K, 3 T separately reaches 1.9 × 105 and 5.87 × 104 A/cm2 for 30-filament wire, and 1.48 × 105 and 4.4 × 104 A/cm2 for 18-filament wire. After twisting, as the TP reduction, the Jc degradation of MgB2 wire is much slower in 30-filament than that in 18-filament at various magnetic fields. At the TP of 5 mm, the Jc degradation comparing with the untwisted wires at 4.2 K and 4 T is up to 30% in 18-filament wire but only about 10% in the 30-filament. This work indicates that the twisting route is very promising to the engineering application of MgB2 superconductor. [ABSTRACT FROM AUTHOR]

Low-cycle fatigue properties and uniaxial ratcheting behavior of a 7050-T6 aluminum alloy were investigated by a non-symmetric cycle stress tests at the normal temperature. The low-cycle fatigue behavior of the alloy was evaluated. The effect of the stress rate, stress amplitudes, and mean stresses on its ratcheting performance was discussed. Considering the ratcheting effect and special working conditions that large mean stresses and small stress amplitudes, based on the same properties under loading, a new fatigue life prediction empirical equation was proposed to estimate the ratcheting life. The results prove that the ratcheting strain of the alloy depends on the stress amplitudes and mean stresses, whereas the stress rate almost has no effect on the ratcheting behavior on account of the rate-independent feature of the material. This equation can give a precise estimate of the ratcheting behavior of large mean stresses and their small amplitudes. [ABSTRACT FROM AUTHOR]

MgB2 bulks with graphene doping were synthesized by high energy ball milling process. The effect of high energy ball milling and graphene doping on the microstructure and critical current density of MgB2 was studied systematically. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and physical property measurement system (PPMS), respectively. The densities of ball-milled graphene-doped samples were larger than those of pure samples. The superconducting properties of MgB2 could be increased by the high energy ball milling process, in comparison with the sample prepared by grinding process. Moreover, the significant improvement of superconducting properties for ball-milled MgB2 samples could be achieved with the addition of graphene. The combination of graphene doping and suitable ball milling could refine the grain and improve the inter-grain connectivity of MgB2. MgB2 with 3 at% graphene doping prepared by high energy ball milling with 2 h exhibited very high critical current density of 6.4 × 105 A/cm2 at 20 K and 0 T. [ABSTRACT FROM AUTHOR]

To develop the multifunctional photosensitizer NaYb1 –xF4: , the effect of Tm3+ concentration on the photosensitivity in NaYb1 –xF4: nanoparticles (NPs) was investigated. Photosensitivity in NaYb1 –xF4: was characterized by chemical probe method, in which 1,3-diphenylisobenzofuran (DPBF) was used as the indicator; and DPBF consumption rate (k) can be used to evaluate the photosensitivity. Experimental results show that in the concentration range of 0–2% for Tm3+, k decreases linearly with increase in Tm3+ concentration with the slope of 0.3. This is mainly attributed to the introduction of fluorescence channel from Yb3+ to Tm3+, which weakens the energy transfer from Yb3+ to oxygen, decreasing k. The result is also confirmed in theoretical analysis. [ABSTRACT FROM AUTHOR]

A Cu- and Cd-resistant bacterial strain, DC-B3, was isolated from heavy metal-contaminated soils in a Cu mine, was identified as belonging to Pseudomonas sp. and biosorbed Cu2+ and Cd2+ from aqueous solution in the present study. Its biosorption properties as a function of environmental parameters such as contact time, initial concentration, pH, temperature and bacterial dosage were investigated through batch experiments, and the removal capacity peaked at pH 6.0, 40 °C and 0.5 g biomass L−1 at an initial concentration of 105 mg L−1. Sorption occurred extremely rapidly at the beginning, equilibrium was reached after approximately 1 h and 4 h for Cu2+ and Cd2+, respectively, and the biosorption kinetic data for both metals were well fitted by the pseudo-second-order model (r2 > 0.99). Sorption isotherms showed that the adsorptions of both metals were highly favourable, and equilibrium data were better described by the Langmuir model (r2 > 0.98 for Cu2+ and 0.99 for Cd2+), with the estimated maximum sorption capacities of 12.6 and 26.5 mg g−1 for Cu2+ and Cd2+, respectively. Desorption assays suggested that biosorption was a chemical process and that a fraction of the metal ions might have entered the bacterial cells. Fourier transform infrared spectroscopy analysis revealed that hydroxyl, amino, carboxyl and phosphate functional groups on the bacterial cell walls might be mainly responsible for the biosorption, although their contributions to the binding of Cu2+ and Cd2+ were different. This result implied that the strain DC-B3 can be used as a potentially eco-friendly and efficient biosorbent for the remediation of Cu(II) and Cd(II) contaminants. [ABSTRACT FROM AUTHOR]

Ex situ MgB2 is usually considered as with lower critical current density (Jc) compared to the in situ one due to much worse inter-granular connectivity. In this work, we reported the fabrication of ex situ MgB2 superconducting tape without dopants using Monel as sheath materials and Nb as the barrier, which has an excellent Jc of 705 A/mm2 at 4.2 K under 4 T, almost as same as the in situ MgB2 wires. Massive and high-quality precursor powders with small grain sizes and quite low oxygen content were sintered at relatively low temperature and short time, 580 ∘C for 3 h. The effects of heat-treatment conditions and tape thickness on the microstructure and Jc of ex situ MgB2 tapes were discussed. The results suggested that the improvement of grains-connectivity was responsible to the excellent Jc properties of ex situ MgB2 tape. [ABSTRACT FROM AUTHOR]

Effect of preliminary torsional strain on low-cycle fatigue of Q345B steel was studied. The specimens were first 0, 180, and 360_ twisted, then the low-cycle fatigue of Q345B steel was evaluated in the strain range of 0.3–0.8% by the method of axisymmetrical strain. The cycling response, cyclic stress–strain relationship, strain–life relationship, fatigue life prediction model, and seismic stability at different torsion angles were obtained and analyzed. The strain–life curve is shown to slope down as a power function. The fatigue life comes down with preliminary torsional strain at a constant level. The cycling response varied from cyclic hardening to cyclic softening in preliminary torsion, and the cyclic hardening rate increased linearly with the strain amplitude. The parameters of the Coffin–Manson relation are corroborated with experimental data. After heat treatment, the seismic stability of the material is improved, with torsional strain greatly reducing this characteristic. Electron microscope examination of fatigue fracture revealed a fatigue crack initiating on the surface of the specimen. The propagating crack deviated from its direction, and plasticity of the material dropped as a result of preliminary torsional strain. [ABSTRACT FROM AUTHOR]

PtCu-embedded graphene (PtCu/graphene) is one of the high-efficiency catalysts in catalytic oxidation of CO. In this paper, CO catalytic oxidation on PtCu/graphene is studied by density functional theory. According to the calculation, the coadsorption configuration is more stable than the configuration of O2 or CO adsorption on PtCu/graphene. Thus, the reaction mechanism of catalytic CO oxidation is the LH mechanism, which proceeds via two steps with barrier energies of 0.21 eV and 0.52 eV, respectively. Compared with pure Pt/graphene and Cu/graphene, Pt mixed in Cu can lower the barrier energy, improving the catalytic activity. Therefore, the research of PtCu/graphene can provide a certain reference value and guidance for the study of another similar catalytic CO oxidation. [ABSTRACT FROM AUTHOR]

The effect of graphene (G) coated Si, Ti and Nb additions on the superconducting properties of MgB2 was systematically studied. The additives were prepared by a coating process and all introduced powders were scattered and combined with graphene. The coating process was useful for the uniform distribution of additives in MgB2 samples. The additives could effectively make the refinement of MgB2 grain size, which achieved an enhancement of surface pinning. Meanwhile, the densities of all the doped samples were larger than those of pure samples, which ensured a better intergrain connection for supercurrent. Therefore, the critical current density of MgB2 with 8 wt% G coated Nb addition got a significant enhancement due to the improvement of grain connectivity and flux pinning properties. [ABSTRACT FROM AUTHOR]

The effects of microstructure and stress ratio on high cycle fatigue of nickel superalloy Nimonic 80A were investigated. The stress ratios of 0.1, 0.5 and 0.8 were chosen to perform fatigue tests in a frequency of 110 Hz. Cleavage failure was observed, and three competing failure crack initiation modes were discovered by a scanning electron microscope, which were classified as surface without facets, surface with facets and subsurface with facets. With increasing the stress ratio from 0.1 to 0.8, the occurrence probability of surface and subsurface with facets also increased and reached the maximum value at R = 0.5, meanwhile the probability of surface initiation without facets decreased. The effect of microstructure on the fatigue fracture behavior at different stress ratios was also observed and discussed. Based on the Goodman diagram, it was concluded that the fatigue strength of 50% probability of failure at R = 0.1, 0.5 and 0.8 is lower than the modified Goodman line. [ABSTRACT FROM AUTHOR]

Hypoxia-inducible factor 1 (HIF-1) is a crucial transcription factor for the cellular adaptive response to hypoxia, which contributes to multiple events in cancer biology. MicroRNAs (miRNAs) are involved in almost all cellular activities such as differentiation, proliferation, and apoptosis. In this work, we use miRNA microarrays to profile miRNA expression in acute myeloid leukemia (AML) cells with inducible HIF-1α expression, and identify 19 differentially expressed miRNAs. Our study shows that HIF-1α represses the expression of miR-17 and miR-20a by downregulating c-Myc expression. These two miRNAs alleviate hypoxia and HIF-1α-induced differentiation of AML cells. More intriguingly, miR-17 and miR-20a directly inhibit the p21 and STAT3 (signal transducer and activator of transcription 3) expression, both of which can reverse miR-17/miR-20a-mediated abrogation of HIF-1α-induced differentiation. Moreover, we show in vivo that miR-20a contributes to HIF-1α-induced differentiation of leukemic cells. Taken together, our results suggest that HIF-1α regulates the miRNA network to interfere with AML cell differentiation, representing a novel molecular mechanism for HIF-1-mediated anti-leukemic action. [ABSTRACT FROM AUTHOR]

A Gires-Tournois interferometer (GTI) with large dispersion compensation was designed and fabricated according to the requirement of the Yb-doped photonic crystal fiber laser system. The designed GTI can provide an average group delay dispersion (GDD) of −1500 fs and a high reflectance (>99.7%) from 1030 to 1050 nm. The Ion-assisted Deposition (IAD) technique was utilized to manufacture the mirror. Good agreement between the measured and designed results both for reflectance and GDD was achieved. The reflectance during 1030-1050 nm was above 99.5% and the GDD ripple was less than ±300 fs. The GTI was used both in the intracavity dispersion compensation and extracavity pulse compression for the Yb-doped photonic crystal fiber laser system. A mode-locked soliton pulse with a 506-fs duration was recorded. An extracavity pulse compression test showed that the GTI had identical pulse compression capability as the conventional grating pairs while the energy loss was obviously reduced. Our results demonstrated that the HDM, which was able to provide quite a large amount of negative dispersion (∼−8×10 fs), could be an ideal alternative to replace the dispersive compensating grating pairs for the dispersion compensation of the Yb-doped photonic crystal fiber laser system. [ABSTRACT FROM AUTHOR]

Secure division serves as an important primitive for secure multi-party computation and has wide applications in many fields, such as data mining, statistical analysis, collaborative benchmarking, etc. How to collaboratively compute the correct division result without leaking any participants's private data becomes the primary goal of secure division schemes. In this paper, we present a quantum secure division scheme via quantum discrete Fourier transform and quantum measurement. The scheme is proven to be secure against semi-honest parties and colluding parties. Furthermore, under the rational assumption that the first priority for every party is to learn the correct result, our scheme is shown to be incentive compatible. [ABSTRACT FROM AUTHOR]

A novel technique of controlling the evolution of the filamentation was experimentally demonstrated in an argon gas-filled tube. The entrance of the filament was heated by a furnace and the other end was cooled with air, which resulted in the temperature gradient distribution along the tube. The experimental results show that multiple filaments are merged into a single filament and then no filament by only increasing the temperature at the entrance of the filament. Also, the filament can appear and disappear after increasing the local temperature and input pulse energy in turn. This technique offers another degree of freedom to control the filamentation and opens a new way for multi-mJ level monocycle pulse generation through filamentation in the noble gas. [ABSTRACT FROM AUTHOR]

Fe46Co35Ni19/CNTs nanocomposites have been prepared by an easy two-step route including adsorption and heat treatment processes. We investigated the effect of heat treatment conditions on structure, morphology, nanoparticle sizes and magnetic properties of the Fe46Co35Ni19 alloy nanoparticles attached on the carbon nanotubes by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-disperse X-ray spectroscopy (EDS) and vibrating sample magnetometer (VSM). When the reducing temperature changes from 300-450°?, a transition of the crystalline structure from bcc phase to fcc-bcc dual phase and an increase in particle size of Fe46Co35Ni19 nanoparticles together with a local maximum at 350°? are observed. Meanwhile, the saturation magnetization (Ms) for Fe46Co35Ni19 nanoparticles increases with the increase of reducing temperature and the coercivity (Hc) decreases rapidly with a local inimum at 350°?. When the reducing time (tr) changes from 2-5 h, bcc phase is predominant in the Fe46Co35Ni19 alloy particles. Both the particle size and Ms have a maximum at tr = 3 h, and the Hc reaches a maximum at tr = 4 h. [ABSTRACT FROM AUTHOR]

Collaborative virtual assembly design is often considered complicated and hardly achievable, for it requires high real-time performance, platform independence, and model synchronization. In order to satisfy all these requirements, a VRML-based virtual assembly solution is proposed. This paper first presents a synchronous moving-searching algorithm for retrieving information from the basic assembly model (BAM) and target assembly model (TAM) in order to give Internet-based collaborative assembly capabilities to these VRML files. Then, a set of assembly approaches for VRML models are systematically addressed to implement the assembly according to constraints of link relations. The advantages of the algorithm and assembly approaches are their high computational efficiency and ease of implementation, which enriches works of Anton and Gorazd () and Qin et al. () with respect to accessibility and maneuverability of VRML model-based assembly design. Moreover, the realization method of collaborative assembly over the Internet is introduced. Finally, some actual examples of collaborative virtual assemblies systems are provided to illustrate the application of these approaches. [ABSTRACT FROM AUTHOR]

The collective behaviour of a square-lattice Hodgkin-Huxley neural network model with white noise is investigated by numerical methods. It is found that for an intermediate value of noise the Hodgkin-Huxley neurons in the square lattice exhibit an ordered circular structure. However, as the noise level increases, the ordered circular structures are distorted, and eventually totally destroyed. Thereby, the constructive role of appropriately pronounced random perturbations in the studied network is revealed. Furthermore, it is shown that as the diffusive coefficient increases, the typical width of the spatial waves also increases accordingly, which results in a decrease of the number of cycles by a given size of the spatial grid. More interestingly, it is observed that the spatio-temporal coherence resonance is enhanced as the diffusive coefficient is increased. Finally, the dependence of the typical width and the average period of the firing rate function on the diffusive coefficient is studied. Results presented in this paper should prove valuable for the understanding of information processing of neural systems in the presence of noise. [ABSTRACT FROM AUTHOR]

A mixed optimal model approximation is presented to obtain reduced-order models for truly fast descriptor systems. By a projection from truly fast descriptor systems to discrete-time systems, a mixed optimal model approximation for truly fast descriptor systems is transformed to a mixed optimal model approximation of the corresponding discrete-time systems. The structure of the fast descriptor systems is preserved in the model approximation procedure. The expression of the error and its gradient are given explicitly in terms of the solutions of certain Lyapunov equations. A numerical example is provided to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

After the transfection of a-1,3-fucosyltransferase (FucT)-VII cDNA into H7721 human hepatocarcinoma cells, the protein expression of some cyclins, cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDIs) p16INK4 and p21waf1/Cip1 were unchanged. However, CDI p27Kip1 protein, both the total amount and the amount that bound to CDK2, but not its mRNA, was significantly reduced. The de-inhibited CDK2 stimulated the phosphorylation of retinoblastoma (Rb) protein and facilitated the G1/S transition and growth rate of the cells. The decrease of p27Kip1 protein, the increase of CDK2 activity and Rb phosphorylation, as well as the cell growth and percentage of S phase cells were correlated to the increased amount of cell surface sialyl Lewis X (SLex) antigen in cells with different a-1,3-FucT-VII expression. The reduction in p27Kip1 and the difference in its expression among different transfected cells were blocked by the SLex antibody KM93 in a dose-dependent manner, indicating that p27Kip1 expression was influenced by a-1,3-FucT-VII and its product SLex. The MEK/MAPK signaling pathway was more important than the PI-3K pathway in the regulation of p27Kip1 expression. [ABSTRACT FROM AUTHOR]

After the transfection of a-1,3-fucosyltransferase (FucT)-VII cDNA into H7721 human hepatocarcinoma cells, the protein expression of some cyclins, cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDIs) p16INK4 and p21waf1/Cip1 were unchanged. However, CDI p27Kip1 protein, both the total amount and the amount that bound to CDK2, but not its mRNA, was significantly reduced. The de-inhibited CDK2 stimulated the phosphorylation of retinoblastoma (Rb) protein and facilitated the G1/S transition and growth rate of the cells. The decrease of p27Kip1 protein, the increase of CDK2 activity and Rb phosphorylation, as well as the cell growth and percentage of S phase cells were correlated to the increased amount of cell surface sialyl Lewis X (SLex) antigen in cells with different a-1,3-FucT-VII expression. The reduction in p27Kip1 and the difference in its expression among different transfected cells were blocked by the SLex antibody KM93 in a dose-dependent manner, indicating that p27Kip1 expression was influenced by a-1,3-FucT-VII and its product SLex. The MEK/MAPK signaling pathway was more important than the PI-3K pathway in the regulation of p27Kip1 expression. [ABSTRACT FROM AUTHOR]

Examines the fatigue behavior of 7075/T6 and 6061/T6 aluminum alloys in the very long life regime using piezoelectric accelerated fatigue tests. Mechanism of fatigue crack initiation and propagation; Fracture surfaces of the alloys; Initiation of voids during continued cyclic deformation; Microstructure; Chemical composition of the alloys.