On August 7 and 8, 2010, a catastrophic debris flow disaster occurred in Zhouqu County in northwestern China’s Gansu Province. The large-scale debris flow event destroyed more than 200 buildings, ...killing approximately 1,700 people. Field investigations showed that the debris flow disaster was not only a natural hazard but also anthropogenic. First, the partial implemented check dams had not formed an integral blocking system to resist large events. Second, poor-quality workmanship contributed to the breakage of check dams. Third, disorderly placement of houses and buildings on the fan structure rendered the cross-sectional area of drainage channel too small to accommodate such a large event. The lessons learned from these hazards may be valuable for improving protective measures against these types of very large debris flow events in northwestern China in the future.
Molecular junctions offer unique opportunities for controlling charge transport on the atomic scale and for studying energy conversion. For example, quantum interference effects in molecular ...junctions have been proposed as an avenue for highly efficient thermoelectric power conversion at room temperature. Toward this goal, we investigated the effect of quantum interference on the thermoelectric properties of molecular junctions. Specifically, we employed oligo(phenylene ethynylene) (OPE) derivatives with a para-connected central phenyl ring (para-OPE3) and meta-connected central ring (meta-OPE3), which both covalently bind to gold via sulfur anchoring atoms located at their ends. In agreement with predictions from ab initio modeling, our experiments on both single molecules and monolayers show that meta-OPE3 junctions, which are expected to exhibit destructive interference effects, yield a higher thermopower (with ∼20 μV/K) compared with para-OPE3 (with ∼10 μV/K). Our results show that quantum interference effects can indeed be employed to enhance the thermoelectric properties of molecular junctions.
It is prevailingly thought that estrogen signaling is not involved in development of estrogen receptor (ER)-negative breast cancer. However, there is evidence indicating that ovariectomy prevents the ...development of both ER-positive and -negative breast cancer, suggesting that estrogen signaling is involved in the development of ER-negative breast cancer. Previously, our laboratory cloned a variant of ER-α, ER-α36, and found that ER-α36 mediated nongenomic estrogen signaling and is highly expressed in ER-negative breast cancer cells. In this study, we found that ER-α36 was highly expressed in 10/12 cases of triple-negative breast cancer. We investigated the role of mitogenic estrogen signaling mediated by ER-α36 in malignant growth of triple-negative breast cancer MDA-MB-231 and MDA-MB-436 cells that express high levels of ER-α36 and found that these cells strongly responded to mitogenic estrogen signaling both in vitro and in vivo. Knockdown of ER-α36 expression in these cells using the small hairpin RNA method diminished their responsiveness to estrogen. ER-α36 physically interacted with the EGFR/Src/Shc complex and mediated estrogen-induced phosphorylation of epidermal growth factor receptor (EGFR) and Src. EGFR signaling activated ER-α36 transcription through an AP1 site in the ER-α36 promoter, and ER-α36 expression was able to stabilize EGFR protein. Our results, thus demonstrated that ER-α36 mediates nongenomic estrogen signaling through the EGFR/Src/ERK signaling pathway in ER-negative breast cancer cells and suggested that a subset of ER-negative breast tumors that expresses ER-α36, retains responsiveness to mitogenic estrogen signaling.
Understanding the deformation behavior of metallic materials containing nanotwins (NTs), which can enhance both strength and ductility, is useful for tailoring microstructures at the micro- and nano- ...scale to enhance mechanical properties. Here, we construct a clear deformation pattern of NTs in austenitic stainless steel by combining in situ tensile tests with a dislocation-based theoretical model and molecular dynamics simulations. Deformation NTs are observed in situ using a transmission electron microscope in different sample regions containing NTs with twin-lamella-spacing (λ) varying from a few nanometers to hundreds of nanometers. Two deformation transitions are found experimentally: from coactivated twinning/detwinning (λ < 5 nm) to secondary twinning (5 nm < λ < 129 nm), and then to the dislocation glide (λ > 129 nm). The simulation results are highly consistent with the observed strong λ-effect, and reveal the intrinsic transition mechanisms induced by partial dislocation slip.
Adsorption of Pb2+, Cd2+, Cu2+ and Cr3+ from aqueous solutions onto titanate nanotubes (TNTs) in multiple systems was systematically studied. Particular attention was paid to competitive adsorption ...and the effect of inorganic ions. TNTs showed large adsorption capacity for the four heavy metals, with the mechanism of ion-exchange between metal ions and H+/Na+ located in the interlayers of TNTs. Binary or quaternary competitive adsorption indicated that the adsorption capacity of the four heavy metals onto TNTs followed the sequence of Pb2+ (2.64mmolg−1)≫Cd2+ (2.13mmolg−1)>Cu2+ (1.92mmolg−1)≫Cr3+ (1.37mmolg−1), which followed the reverse order of their hydration energies. Moreover, inorganic ions including Na+, K+, Mg2+ and Ca2+ inhibited the adsorption of heavy metals on TNTs, because they competed for adsorption sites, decreased the activity of heavy metal ions, and promoted the aggregation of TNTs. However, Al3+ and Fe3+ generally enhanced adsorption because the resulting hydroxyl-Al/Fe intercalated or coated TNTs could also capture metal ions. Furthermore, minor effect of inorganic ions on adsorption of Pb2+ resulted from its strong affinity to TNTs. Difficult desorption and small inhibiting effect by Na+, K+, Mg2+ and Ca2+ on adsorption of Cr3+ was due to the formed stable complex of HOCr(OTi)2 with TNTs. Present study indicated potential applications of TNTs in wastewater treatment for heavy metals.
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•Adsorption capacity was closely related to heavy-metal's hydration energy.•Pb2+ with strong affinity to TNTs led to minor effect of inorganic ions.•Difficult desorption of Cr3+ owed to the stability of complex HOCr(OTi)2.•Al3+/Fe3+ promoted adsorption due to hydroxyl-Al/Fe intercalated/coated on TNTs.•Effect of co-existing ions on heavy metal adsorption was based on ion-exchange.
FeCoNiCrMnTi high entropy alloy (HEA) coatings has been proved the combined high hardness and good corrosion resistance. In order to improve wear resistance of stirrer in sewerage plants, ceramic ...particle reinforced FeCoNiCrMnTix (atomic ratio x = 0, 0.5, 1.0, 1.5) HEA coatings were produced on the surface of austenite stainless steel by laser cladding. The influence of atomic ratio of titanium in high entropy alloys on the number of ceramic, microstructure, tribology and corrosion behavior at room temperature of the laser cladding coatings were studied. Experimental results revealed that the cladding coatings were mainly composed of FCC-type solid solution. With the addition of titanium, TiN particle was in-situ produced in the coating at high purity N2 gas protection. In addition, Ti(Fe,Co,Ni,Cr)2 Laves phase was found while x is more than 1.0. With the increase of titanium content, the amount of TiN in the coating increased, which improved the wear resistance of the coating. However, corrosion and crack resistance of the coating decreased while Ti content exceeded 1.0. The coating of FeCoNiCrMnTi0.5 had about 1.9 times of wear resistance of the substrate, and its corrosion resistance was almost same as the substrate.
•TiN reinforced FeCoNiCrMnTix coatings were fabricated by laser cladding process at nitrogen atmosphere.•TiN and laves phase play an important role on the performance regulation of laser clad coatings.•The content of Ti is the key point affecting the wear resistance and corrosion resistance of the coating.
The key to manufacturing magnesium-based alloys that are suitable as biodegradable orthopaedic implants is how to adjust their degradation rates and mechanical integrity in the physiological ...environment. In this study, to solve this challenge, a soluble Ca-deficient hydroxyapatite (Ca-def HA) coating was deposited on an Mg–Zn–Ca alloy substrate by pulse eletrodeposition. This deposition can be demonstrated by X-ray diffractometry and energy dispersion spectroscopy analyses, and the Ca/P atomic ratio of as-deposited coating is about 1.33 (within the range from 1.33 to 1.65). By regulating the appropriate pulse amplitude and width, the Ca-def HA coating shows better adhesion to Mg–Zn–Ca alloy, whose lap shear strength is increased to 41.8
±
2.7
MPa. Potentiodynamic polarization results in Kokubo’s simulated body fluid (SBF) indicate that the corrosion potential of Mg alloy increases from −1645 to −1414
mV, while the corrosion current density decreases from 110 to 25
μA/cm
2, which illustrates that the Ca-def HA coating improves the substrate corrosion resistance significantly. Since orthopaedic implants generally serve under conditions of stress corrosion, the mechanical integrity of the Mg–Zn–Ca alloy was measured using the slow strain rate tensile (SSRT) testing technique in SBF. The SSRT results show that the ultimate tensile strength and time of fracture for the coated Mg–Zn–Ca alloy are higher than those of the uncoated one, which is beneficial in supporting fractured bone for a longer time. Thus Mg–Zn–Ca alloy coated with Ca-def HA is be a promising candidate for biodegradable orthopaedic implants, and is worthwhile to further investigate the in vivo degradation behavior.
Superconductivity and charge density waves (CDWs) are competitive, yet coexisting, orders in cuprate superconductors. To understand their microscopic interdependence, a probe capable of discerning ...their interaction on its natural length and time scale is necessary. We use ultrafast resonant soft x-ray scattering to track the transient evolution of CDW correlations in YBa
Cu
O
after the quench of superconductivity by an infrared laser pulse. We observe a nonthermal response of the CDW order characterized by a near doubling of the correlation length within ≈1 picosecond of the superconducting quench. Our results are consistent with a model in which the interaction between superconductivity and CDWs manifests inhomogeneously through disruption of spatial coherence, with superconductivity playing the dominant role in stabilizing CDW topological defects, such as discommensurations.
Precision spectroscopy of the hydrogen molecule is a test ground of quantum electrodynamics (QED), and it may serve for the determination of fundamental constants. Using a comb-locked cavity ...ring-down spectrometer, for the first time, we observed the Lamb-dip spectrum of the R(1) line in the overtone of hydrogen deuteride (HD). The line position was determined to be 217 105 182.79±0.03_{stat}±0.08_{syst} MHz (δν/ν=4×10^{-10}), which is the most accurate rovibrational transition ever measured in the ground electronic state of molecular hydrogen. Moreover, from calculations including QED effects up to the order m_{e}α^{6}, we obtained predictions for this R(1) line as well as for the HD dissociation energy, which are less accurate but signaling the importance of the complete treatment of nonadiabatic effects. Provided that the theoretical calculation reaches the same accuracy, the present measurement will lead to a determination of the proton-to-electron mass ratio with a precision of 1.3 parts per billion.
In this work, the modification of hard jets in an extended static medium held at a fixed temperature is studied using three different Monte Carlo event generators: linear Boltzmann transport (LBT), ...modular all twist transverse-scattering elastic-drag and radiation (MATTER), and modular algorithm for relativistic treatment of heavy-ion interactions (MARTINI). Each event generator contains a different set of assumptions regarding the energy and virtuality of the partons within a jet versus the energy scale of the medium and, hence, applies to a different epoch in the space-time history of the jet evolution. Here modeling is developed where a jet may sequentially transition from one generator to the next, on a parton-by-parton level, providing a detailed simulation of the space-time evolution of medium modified jets over a much broader dynamic range than has been attempted previously in a single calculation. Comparisons are carried out for different observables sensitive to jet quenching, including the parton fragmentation function and the azimuthal distribution of jet energy around the jet axis. The effect of varying the boundary between different generators is studied and a theoretically motivated criterion for the location of this boundary is proposed. Lastly, the importance of such an approach with coupled generators to the modeling of jet quenching is discussed.
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