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Being light, cheap, breathable and foldable, paper is emerging as a new type of substrate for flexible thermoelectric films. Several techniques including soaking and magnetron sputtering have been developed to coat inorganic semiconductors onto paper substrate, but the flexibility and thermoelectric performance of the resulting films are still far from satisfactory. This work implements a novel glass-fiber-aided cold-press method for achieving flexible n-type Ag2Te nanowire (NW) films on copy-paper substrate. A greatly enhanced electrical conductivity has been realized in Ag2Te NWs film due to the disappearance of grain boundaries under compression to 30 MPa. As a consequence, the largest power factor (PF) value of up to 192 μW (mK2)−1 at 195 °C surpasses the performance of paper based thermoelectric films reported previously. Moreover, the PF value only decreases by 20% after 500 bending cycles, suggesting the good flexibility of the copy-paper supported Ag2Te NWs films. A thermoelectric module containing 10 pieces of series-connected Ag2Te films is fabricated using this glass-fiber-aided cold-press method. With ΔT increasing from 20 K to 80 K, the open-circuit voltage of module continually increases from about 11 mV to 60 mV. This measurement of open-circuit voltage has been repeated 10 times to confirm the stability of paper-supported Ag2Te thermoelectric module. The glass-fiber-aided cold-press method in this study provides an effective access to high-performance, flexible and solvent-processable inorganic thermoelectric films on copy-paper substrate.

An experimental investigation on the performance of an ejector applied in a refrigeration system is conducted. The system uses R134a as a working fluid. The experimental results indicate that back pressure plays an important role in the entrainment ratio of an ejector because this parameter determines the operation mode of an ejector under certain primary fluid pressure and secondary fluid pressure. Increasing in the primary fluid pressure can improve the critical back pressure while deteriorate the best performance of an ejector. Moreover, an optimal value of the primary fluid pressure exists corresponding to a maximum value of the entrainment ratio under a given condition. A logarithmic relation is developed to predict the critical back pressure and to determine operating conditions in a R134a ejector refrigeration system. The research findings will be meaningful for researchers to have a better understanding of the R134a ejector applied in a refrigeration system.

With a high flexibility and an adjustable electronic structure, reduced graphene oxide (RGO) is a potential candidate for flexible thermoelectric materials. Here, we report that flexible RGO/tellurium nanowires (Te NWs)/RGO sandwich structure hybrid films are prepared on glass fabrics through the drop-cast method. The addition of 20 wt.% Te NWs into a RGO matrix remarkably improves the Seebeck coefficient from 15.2 μV/K to 89.7 μV/K while maintaining relatively high electrical conductivity, thus resulting in a one order of magnitude higher power factor value compared with the Te NWs. According to the values of carrier mobility and concentration of hybrid films, the improved thermoelectric properties are presented because of the energy filtering effect on the interfaces in hybrid films. This article suggests that RGO/Te NWs/RGO hybrid films would be promising for fabricating flexible energy sources.

A high resolution global ocean–sea ice model is employed to investigate the impacts of open-ocean deep convection on coastal and bottom water temperature in the Weddell Sea. The imposed strong and persistent cyclonic wind forcing and the large loss of bottom water weaken the stratification and eventually trigger the occurrence of open-ocean deep convection in the southern limb of the Weddell Gyre in this model. The production rate of the bottom water induced by the deep convection is estimated to be about 5 Sv (1 Sv = 106 m3/s) for a polynya with a similar size to that of the observed Weddell Polynya in the mid-1970s. The cooling induced by deep convection at mid-depth is transported towards the shelf regions by standing meanders or eddies to affect the basal melting of ice shelves, and is transported westward by an intensified slope current; interior coastal temperature in regions with a broader continental shelf is less affected by the deep convection, as the intensified slope current acts to suppress heat exchanges across the shelf break. Also, the deep convection causes warming in the Weddell bottom water around the convection site, when the simulated polynya size is similar to that of the observed Weddell Polynya in the mid-1970s. This finding sheds light on the observed non-monotonic decadal change (cooling between 1984–1992 and warming between 1998–2008) in the Weddell bottom water temperature. When the simulated polynya further develops into a large size across the Weddell Sea, the sustained broad deep convection causes large cooling in the bottom water in the western Weddell Sea and warming in the eastern Weddell Sea, with the bottom water temperature also being strongly modulated by a greatly intensified Weddell Gyre.

Due to the exhaustion of rare metal resources and the hazard of toxic material to the environment, development of cost-effective, nontoxic, and earth-abundant thermoelectric materials has become more urgent. This study introduces a nontoxic, earth abundant n-type iron-based cost-effective Fe–2.3C–Si–5Mn–7V–8Cr thermoelectric material that is prepared by a simple melting method. Significant increase in both electrical conductivity and Seebeck coefficient are achieved by several heat treatment processes to optimize the distribution and grain size of VC, Cr 23-x Fe x C 6 typed chromium carbide as well as base matrix. As a result, the power factor of the sample that is normalized at 1150 °C is about 0.75 mWm −1 K −2 in maximum value, which is 2.6 times larger than that (0.29 mWm −1 K −2 ) of as-cast sample. The highest ZT value of the sample that is normalized at 1150 °C is 0.028 at 868 K, which is 4.3 times larger than that of as-cast sample (0.0065 at 964 K) in present study, indicating that a proper heat treatment process would remarkably enhance ZT value. This research provides extremely valuable data for the future researches on thermoelectric alloys.

In contrast with the severe thinning of ice shelves along the coast of West Antarctica, large ice shelves (specifically, the Filchner–Ronne and Amery Ice Shelves) with deep grounding lines gained mass during the period 1994–2012. This positive mass budget is potentially associated with the marine ice production, which originates from the supercooled Ice Shelf Water plume carrying suspended frazil ice along the ice shelf base. In addition, the outflow of this supercooled plume from beneath the ice shelf arguably exerts a significant impact on the properties of Antarctic Bottom Water, as well as its production. However, knowledge of this buoyant and supercooled shear flow is still limited, let alone its structure that is generally assumed to be vertically uniform. In this study we extended the vertical one-dimensional model of ice shelf–ocean boundary current from Jenkins (2016) by incorporating a frazil ice module and a fairly sophisticated turbulence closure (i.e., k - e model) with the effects of density stratification. On the basis of this extended model, the study reproduced the measured thermohaline properties of a perennially-prominent supercooled ice shelf–ocean​ boundary current underneath the Amery Ice Shelf in East Antarctica, and conducted extensive sensitivity runs to a wide range of factors, including advection of scalar quantities, far-field geostrophic currents, basal slope, and the distribution of frazil ice crystal size. Based on the simulation results, the following conclusions can be drawn: Firstly, it can be difficult to reasonably reproduce the vertical structure of the ice shelf–ocean boundary current using a constant eddy viscosity/diffusivity near the ice shelf base. Secondly, although there are no direct observations of the size of frazil ice crystals beneath the ice shelves, the size of the finest ice crystals that play an important role in controlling the ice shelf–ocean boundary current is strongly suggested. Lastly, but most importantly, the ice shelf–ocean boundary layer response to the vertical gradient of frazil ice concentration will significantly reduce the level of turbulence. Therefore, this study highlights the importance of the strong interaction between frazil ice formation and the hydrodynamics and thermodynamics of ice shelf–ocean boundary layer. This interaction must not only be included, but also be resolved at high resolutions in three-dimensional coupled ice shelf–ocean models applied to cold ice cavities, which will have a potential impact on the overall ice shelf mass balance and the Antarctic Bottom Water production.

Carbon coated stainless-steel (SS) electrode has been suggested to be a powerful composite electrode with high conductivity, excellent biocompatibility and good mechanical strength, which is promising for scaling up the bioelectrochemical systems (BESs). However, the already reported carbon coating methods were independent on the production of SS material. Additional steps and investment of equipment for carbon coating are costly, and the industrialization of these carbon coating processes remains challenging. In this study, we report an industrializable carbon coating approach that was embedded into the production line of the SS wire, which was realized through a wire-drawing process with graphite emulsion as the lubricant and carbon source. We found the slide of SS wire through the dies was essential for the graphite coating in terms of loading amount and stability. When the graphite coated SS wire was prepared as the anode and operated in a BESs, the current density reached 1.761 ± 0.231 mA cm−2, which was 20 times higher than that without graphite coating. Biomass analysis was then conducted, confirming the superior bioelectrochemical performance was attributed to the improvement of biocompatibility by the graphite coating layer. Furthermore, graphite coating by the wire-drawing process was systematically compared with the existing methods, which showed a comparable or even better bioelectrochemical performance but with extremely low cost (0.036 $·m−2) and seconds level of the time consumption. Overall, this study offers a cost-effective and industrializable approach to preparing graphite coated SS electrode, which may open up great opportunities to promote the development of BESs at large scale.

Pyridine and organics containing pyridine rings are widely used but persist in the environment and cause toxic pollution. Due to the attraction of the nitrogen atoms to the electrons in the pi bond, the pyridine ring is difficult to oxidize by oxidant. Here, we propose that ultraviolet (UV) irradiation activates the electrons in the pi bond and enables combination with the hydroxyl radical ( OH) originating from hydrogen peroxide (H2O2) to eliminate pyridine quickly and mineralize the byproducts. The removal rates of pyridine and total organic carbon (TOC) were compared in different treatments: UV irradiation, UV/H2O2 treatment and Fenton oxidation with different initial pyridine concentrations, pH values and H2O2 concentrations. The UV/H2O2 treatment yielded a higher pyridine removal rate and greater mineralization than the other treatments. The removal rate of pyridine was highest in neutral aqueous solution and H2O2 concentration of 10 mM. At an initial H2O2 concentration of 10 mM, more than 90% of the pyridine was degraded in 10 min, and approximately 70% of the TOC was removed in 60 min. The absorption of UV light at 254 nm by the pi bond of pyridine can accelerate the damage to the stable pyridine structure, especially in the presence of OH. This study provides a promising alternative for the removal and mineralization of pyridine ring-containing materials.

In this study, we report a power factor (PF) value as high as 1950 μW m−1 K−2 for B-ion implanted thermoelectric Si1-x-yGexSny ternary alloy films at ambient temperature by radio frequency sputtering followed by a short-term rapid thermal annealing heat treatment. The record high PF value was realized by modulation doping of Sn in the Si1-x-yGexSny film. It was found that using metallic Sn as nanoparticles and Si1-x-yGexSny as the matrix leads to a large enhancement of the carrier concentration and a very small decrease in carrier mobility. As a result, the electrical conductivity and power factor of the modulation doped Si1-x-yGexSny alloy were greatly improved. The findings of this study present emerging opportunities for the modulation of Si integration thermoelectrics as wearable devices charged by body temperature.

Two-dimensional (2D) metal-diboride ZrB

Persistent outflow of supercooled Ice Shelf Water (ISW) from beneath McMurdo Ice Shelf creates a sub-ice platelet layer (SIPL) having a unique crystallographic structure under the sea ice in McMurdo Sound (MMS), Antarctica. A new frazil-ice-laden ISW plume model that encapsulates the combined nonlinear effects of the vertical distributions of supercooling and frazil ice concentration (FIC) on frazil ice growth is applied to MMS, and is shown to reproduce the observed ISW supercooling and SIPL distributions. Using this model, the dependence of SIPL thickening rate on ISW supercooling in MMS is investigated. Results are found to be sensitive to the choice of frazil ice suspension index, which determines the vertical distribution of FIC. For each suspension index, SIPL thickening rate can be expressed as an exponential function of ISW supercooling. The complex dependence on FIC highlights the need to improve frazil ice observations within the ice-ocean boundary layer.

Highly-flexible thermoelectric hybrid films based on reduced graphene oxide (RGO) and tellurium nanowire (Te NW) layered structure are fabricated via vacuum filtration. The electrical conductivity and Seebeck coefficient of the optimized hybrid film can reach 978 S m−1 and 286 μV K−1, respectively, pushing the power factor (PF) value up to 80 μW (m K2)−1 at 40 °C, approximately 80 times larger than the pure Te NW film, possibly due to the combination of the high carrier concentration of RGO and high carrier mobility of Te NWs. Meanwhile, the transport characteristics of hybrid films were revealed by the measurements of electrical conductivity, Seebeck coefficient, and Hall effect. This article provides a possible access to high-performance and flexible TE films based on RGO sheets and inorganic semiconductors.

For decades, scientists have devoted themselves to developing vanadium dioxide (VO2) films for thermochromic smart windows, but there remains a major challenge to their large-scale implementation owing to their limited solar modulation ability. Here, we show a new method for improving their solar modulation ability via increasing optical switching in the visible region upon phase transition. VO2-based composite films that exhibited reduced haze (haze(555) (nm) down from 46.5% to 2.2% @RT), improved luminous transmittance (up from 9.6% to 38.5% @RT) and enhanced solar modulation ability (Delta T-sol up from 8.1% to 16.9% @RT) have been fabricated by a convenient and controllable approach. With this method, the mean sizes of VO2 particles can be easily tuned from 150 nm to 40 nm by varying the preparation parameters. Via a combination of the optical transmittance spectrum and Mie calculations, we first observed the behavior of optical switching in the visible region upon phase transition, which is size-dependent. Moreover, distinctive size effects on variations in the band gap energy and specific interband transitions were studied based on the absorption spectra of VO2 composite films.

The simultaneous improvement of electrical conductivity (σ) and Seebeck coefficient (S) is essential to realize the thermoelectric materials with high power factor value. Here, we report the discovery that the redox reaction happened between the reduced graphene oxide (RGO) sheets and tellurium (Te) nanowires can lead to a simultaneous improvement of σ and S in the RGO/Te nanowires hybrid films. With optimization, the electrical conductivity and Seebeck coefficient can reach 633 S/m and 382 μV/K, respectively, pushing the power factor value up to 68.4 μW/(mK2), approximately 25 times larger than the reported pure Te nanowires film. Based on all of the characterizations, the redox reaction between the RGO sheets and Te nanowires have been confirmed and the transportation characteristics of the hybrid films are predicted. We demonstrate the new approach that via turning the redox reaction, the interfacial interaction can be optimized, enabling a novel flexible thermoelectric films with superior performance. To our knowledge, this is the first time that the TE properties of RGO/inorganic hybrid films are reported.

With high carrier mobility and low cost, reduced graphene oxide (RGO) shows bright prospects for use in the field of thermoelectric materials. To investigate the intrinsic thermoelectric properties of RGO sheets, we prepared RGO papers which were reduced by HBr solution for 5 min, 20 min, and 60 min, respectively. Thermogravimetry analysis (TGA) and Raman analysis showed that the conjugated carbon network of graphene oxide (GO) was restored during the reduction process and the thermal stability of the RGO papers was much better than that of GO paper. The RGO paper that was reduced for 60 min and then annealed in Ar/H2 atmosphere exhibited the highest electrical conductivity of 3.22 × 105 S/m at 160°C. As the reduction degree of the RGO paper deepens, the Seebeck coefficient gradually transforms from positive to negative, indicating that the conduction type of RGO paper can be controlled by regulating the reduction degree.

Direct measurements of Kuroshio at its origin (18 degrees N, east of the Luzon Island) are conducted from November 2010 to October 2012. It is found that the depth-averaged Kuroshio between 200 and 700 m has increased over 15 cm s(-1) during the 2 year observational period and it is accompanied by the pronounced southward shift of the North Equatorial Current (NEC) bifurcation. Further analysis indicates that the Kuroshio's strengthening is confined to the upstream segment east of the Luzon Island while the Kuroshio decreased as it passed the Luzon Strait due to a dipole-like sea surface height (SSH) trend between 15 degrees N and 23 degrees N. It is demonstrated that the 2 year strengthening of the Kuroshio, as well as the dipole-like SSH trend can be adequately reproduced by a 1.5 layer nonlinear reduced gravity model, suggesting an important role of upper ocean response to low-frequency wind forcing in the western Pacific. Salinity at 500 m depth is also found to increase during the concurrent 2 years. This subthermocline salinity increase is a combined outcome of vertical (basin-scale isopycnal surface movement) and horizontal advections (i.e., strengthened Kuroshio) due to changes in the large-scale wind-driven ocean circulation.

Two-dimensional (2D) metal-diboride ZrB2 monolayers was predicted theoretically as a stable new electronic material [A. Lopez-Bezanilla, Phys. Rev. Mater., 2018, 2, 011002 (R)]. Here, we investigate its electronic transport properties along the zigzag (z-ZrB2) and armchair (a-ZrB2) directions, using the density functional theory and non-equilibrium Green's function methods. Under low biases, the 2D ZrB2 shows a similar electrical transport along zigzag and armchair directions as electric current propagates mostly via the metallic Zr-Zr bonds. However, it shows an electrical anistropy under high biases, and its I-V curves along zigzag and armchair directions diverge as the bias voltage is higher than 1.4 V, as more directional B-B transmission channels are opened. Importantly, both z-ZrB2 and a-ZrB2 show a pronounced negative differential conductance (NDC) effect and hence they can be promising for the use in NDC-based nanodevices.

Pure phase V1−xWxO2(M/R) nanorods with superb metal–insulator transition properties were obtained in tungsten (W)-doped level ranges from 0.5 to 2.0 at% using a one-step hydrothermal treatment without additional annealing steps. The assured level of W doping greatly promotes the grain growth of pure phase vanadium oxide (VO2)(M/R) and simultaneously the phase transition temperature (Tc) is depressed as much as 103 °C per at% W for the V1−xWxO2 nanorods when x = 1.0–2.0 at%. After mixing the pure phase VO2(M) (W-doped 0.5 at%, phase transition at 47 °C) nanorods with acrylic resin, the integrated visible transmission of the VO2 composite coating on glass is up to 60.6% and the integrated solar modulation efficiency is up to 10.3%. These results mean that the superior thermochromic property will greatly favor the practical application of VO2-based smart windows.

Nb-doped SrTiO3 bulk materials with high quality are fabricated using a facile process. The doping level in SrTiO3 is controlled in a doping range of 0–20 mol%. Thermoelectric response including electrical conductivity σ, Seebeck coefficient S, and thermal conductivity k has been investigated in a high-temperature regime above 300 K. The ZT values show obvious doping-level dependences, in which the largest value as high as 0.37 at 1000 K and 0.40 at 1100 K is realized in the optimized doping range of 10–15 mol%. This is the first time such a remarkable thermoelectric performance was accomplished in electron-doped SrTiO3 ceramics.

By using a molecular dynamics method with EAM potential, we study the evolution phenomena of metal twist grain boundaries (GBs) in the [100], [111] and [110] orientations, together with their bimetal interface, under anticlockwise and clockwise torsions. Our results show that there are different evolution behaviors of the GB screw dislocations for single metals (Al and Ni) and their bimetal interface (Al/Ni) under torsion. Specifically, for the single metals in the [100] and [111] orientations, their GBs evolve toward lower or higher angle twist GBs depending on the twist direction. For Ni in the [110] orientation, the dislocations spread not only in the GB region but also in the grain interior. However, for the bimetal interface, the propagation of dislocations is not only reduced dramatically but also limited to the interface region, showing that there is an inhibition effect. Therefore, such an inhibition effect can enhance the stability of nanomaterials which is very useful for the further design of nanodevices.

Polyploidy can lead to aneuploidy and tumorigenesis. Here, we report that the Hippo pathway effector Yap promotes the diploid-polyploid conversion and polyploid cell growth through the Akt-Skp2 axis. Yap strongly induces the acetyltransferase p300-mediated acetylation of the E3 ligase Skp2 via Akt signaling. Acetylated Skp2 is exclusively localized to the cytosol, which causes hyper-accumulation of the cyclin-dependent kinase inhibitor p27, leading to mitotic arrest and subsequently cell polyploidy. In addition, the pro-apoptotic factors FoxO1/3 are overly degraded by acetylated Skp2, resulting in polyploid cell division, genomic instability, and oncogenesis. Importantly, the depletion or inactivation of Akt or Skp2 abrogated Hippo signal deficiency-induced liver tumorigenesis, indicating their epistatic interaction. Thus, we conclude that Hippo-Yap signaling suppresses cell polyploidy and oncogenesis through Skp2.

In a very recent experimental work [Gao et al., 2018 Adv. Mater. 30, 1707055], a graphene-like CuSe monolayer was realized. Motivated by this success, we performed first-principles calculations to investigate its electronic transport and photoelectronic properties. We find that the CuSe ML shows a strong electrical anisotropy, and its current-voltage (I-V) curves along the zigzag and armchair directions are noticeably different. The CuSe ML also displays a useful negative differential resistance (NDR) effect along the both directions when the bias is beyond 1.0 V. Moreover, it has a large photon absorption to orange light. Our study suggests that CuSe ML is a multifunctional material and has various potential applications in electrical-anisotropy-based, NDR-based, and even optical nanodevices., Comment: Journal of Physics: Condensed Matter 2019

Atomic motion and the structure response of grain boundaries (GBs) are essential to the plastic deformation of small-volume polycrystal systems, especially for thin materials that exhibit some dramatic characteristics. Here, the microstructure and properties of thin Ni/Ni3Al (0 0 1) with the uniaxial tension of twist GBs are investigated using molecular dynamics (MD) simulations with an embedded atom (EAM) potential. We find that low angle twist GB dislocations propagate mainly from the corners to the center of the interface, and for high angle twist GBs they originate from the edge of the interface but do not extend to the center. In the process of plastic deformation, both low angle and high angle twist GB fractures occur in the center of the interface, which is completely different from the situation of thick materials reported by other references. More interestingly, the fracture patterns between low angle and high angle twist GBs exhibit extremely different performance due to the different characteristics of the initial dislocation structures in the interfaces.

The structural and dynamical properties of rapidly quenched Al are studied by molecular dynamics simulations. The pair-correlation function of high temperature liquid Al agrees well with the experimental results. Different cooling rates are applied with high cooling rates leading to glass formation, while low cooling rates leading to crystallization. The local structures are characterized by Honeycutt–Andersen indices and Voronoi tessellation analysis. The results show that for high cooling rates, the local structures of the liquid and glassy Al are predominated by icosahedral clusters, together with considerable amount of face-centered cubic and hexagonal close packed short-range orders. These short-range order results are further confirmed using the recently developed atomic cluster alignment method. Moreover, the atomic cluster alignment clearly shows the crystal nucleation process in supercooled liquid of Al. Finally, the mean square displacement for the liquid is also analyzed, and the corresponding diffusion coefficient as a function of temperature is calculated.

The response of the global subduction rate to global warming was assessed based on a set of Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) models. It was found that the subduction rate of the global ocean could be significantly reduced under a warming climate, as compared to a simulation of the present-day climate. The reduction in the subduction volume was quantitatively estimated at about 40 Sv and was found to be primarily induced by the decreasing of the lateral induction term due to a shallower winter mixed layer depth. The shrinking of the winter mixed layer would result from intensified stratification caused by increased heat input into the ocean under a warming climate. A reduction in subduction associated with the vertical pumping term was estimated at about 5 Sv. Further, in the Southern Ocean, a significant reduction in subduction was estimated at around 24 Sv, indicating a substantial contribution to the weakening of global subduction.

A novel, fast combustion method for synthesizing anatase TiO2 nanoparticles (average diameter ∼14 nm) codoped with N and Nb in a single step is reported. XRD, STEM-EDX, and XPS measurements confirm that Nb ions are incorporated into the tetragonal lattice on Ti sites, while N ions occupy O sites, and likely also interstitial sites. Sintering of pellets of codoped powders under reducing conditions produced polycrystalline samples with the rutile structure. Chemically tuned samples have power factors up to 9.87 × 10–4 W m–1 K–2, 7 times higher than that of pure TiO2 sintered under the same conditions. In addition, the thermal conductivity is considerably lower at 2.6–4.0 W m–1 K–1 as a result of greater grain-boundary and point-defect scattering. The figure of merit, ZT, is improved to 0.35 at 700 °C, which is the highest value reported for a TiO2 material to date, and is comparable to the highest values of any n-type thermoelectric oxide. Our material also exhibits good thermal stability in a pure N2 atmos...

Titania embedded with layer-cracking nanostructures (sodium titanate) was synthesized by a hydrothermal method and a subsequent sintering process. The structure and morphology were determined by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption–desorption experiments. In thermoelectric investigations, this nanocomposite has reduced thermal conductivity, where the minimum reaches about 2.4 W/m K at 700°C. This value is relatively low among the transition-metal oxides. Strong boundary scattering at the interfaces of the layered nanostructures and point defect scattering resulting from volatilization of Na+ ions seem to be main reasons for the suppression of phonon heat transfer. On the other hand, the power factor shows no apparent deterioration. Our results suggest that introduction of proper layer-cracking nanostructures into thermoelectric hosts might be effective to enhance their performance.

The theoretical study of grain boundaries (GBs) in polycrystalline semiconductors is currently stalemated by their complicated nature, which is difficult to extract from any direct experimental characterization. Usually, coincidence-site-lattice models are constructed simply by aligning two symmetric planes ignoring various possible reconstructions. Here, we propose a general self-passivation rule to determine the low-energy GB reconstruction and find new configurations for the CdTe \ensuremath{\Sigma}3 (112) GBs. First-principles calculations show that it has lower formation energies than the prototype GBs adopted widely in previous studies. Surprisingly, the reconstructed GBs show self-passivated electronic properties without deep-level states in the band gap. Based on the reconstructed configurations, we revisited the influence of $\mathrm{CdC}{\mathrm{l}}_{2}$ post-treatment on the CdTe GBs and found that the addition of both Cd and Cl atoms in the GB improves the photovoltaic properties by promoting self-passivation and inducing $n$-type levels, respectively. The present study provides a new route for further studies of GBs in covalent polycrystalline semiconductors and highlights that previous studies on the GBs of multinary semiconductors, which are based on the unreconstructed prototype GB models, should be revisited.

Interfacial friction plays a crucial role in the mechanical properties of carbon nanotube (CNT) based fibers, composites, and devices. With the molecular dynamics simulation, we investigate the compression effect on the friction within the 16 × (10, 10) @ (5, 5) double-walled CNTs. Our results show that the double-walled CNTs has perfect compression and recovery qualities, and its variation in sliding velocity also has good accordance with the single-walled CNTs. The structure transition varies during the three different deformation stages, which can be denoted by before the structure deformation, during the structure deformation, and after the structure deformation, of double-walled CNT under increasing pressure. And we find that, after deformation, the CNT collapse and the friction forces within the double-walled CNTs have at least 1.6 times larger than its beginning. Finally, in order to make comparisons with the same type double-walled CNT bundles, we constructed the 16 × (10, 10) @ (6, 6) bundles in theory and studied its sliding velocity, which shows that larger diameter inner CNTs have higher friction after deformation. This may provide an effective way to reinforce the strengthen of CNT fibers.

Monte Carlo simulations were used to evaluate the uncertainties of a receptor model by factor analysis with non-negative constraints and an artificial data set. The Aroclors were assumed to be the main sources of the polychlorinated biphenyls (PCBs). The Aroclors considered were Aroclor 1016, Aroclor 1248 and Aroclor 1260. The 25 PCB congeners covered the entire range of molecular weights and some congeners were unique to individual Aroclors. The postulated source contributions were developed from 40 postulated samples. The coefficients of variation ( Cv ) of PCB congeners used for the Monte Carlo simulations were 0.1, 0.2, 0.4 and 0.6. The simulations were repeated 1000 times with randomly selected values. The results indicated that if the Cv values were less than 0.4, the receptor model was able to reproduce the source profiles and contributions well. For normally distributed input parameters, the results were also normally distributed, indicating the robustness of the model.

In this paper, 240 abnormal infrasound signals observed at Beijing (39.87°N, 116.48°E) and 92 M ≧ 7.0 worldwide earthquakes during 2002–2008 are investigated. It is found that about 85% the earthquakes are preceded the signals by 1–30 days and the greater M ≧ 7.6 earthquakes are most likely leaded by 1–10 days. The maximum amplitude of the abnormal infrasound signal generally exceeds 8 Pa in sound pressure. The statistical analyses further indicate that the amplitude of the abnormal signals is proportional to the magnitude the associated forthcoming earthquake but inversely to the distance from that earthquake to the observation station.

A prominent feature of recent climatic change is the strong Arctic surface warming that is contemporaneous with broad cooling over much of Antarctica and the Southern Ocean. Longer global surface temperature observations suggest that this contrasting pole-to-pole change could be a manifestation of a multi-decadal interhemispheric or bipolar seesaw pattern, which is well correlated with the North Atlantic sea surface temperature variability and thus generally hypothesized to originate from Atlantic meridional overturning circulation oscillations. Here, we show that there is an atmospheric origin for this seesaw pattern. The results indicate that the Southern Ocean surface cooling (warming) associated with the seesaw pattern is attributable to the strengthening (weakening) of the Southern Hemisphere westerlies, which can be traced to Northern Hemisphere and tropical tropospheric warming (cooling). Antarctic ozone depletion has been suggested to be an important driving force behind the recently observed increase in the Southern Hemisphere's summer westerly winds; our results imply that Northern Hemisphere and tropical warming may have played a triggering role at an stage earlier than the first detectable Antarctic ozone depletion and enhanced Antarctic ozone depletion through decreasing the lower stratospheric temperature.

Recently, researchers spare no efforts to fabricate desirable vanadium dioxide (VO2) film which provides simultaneously high luminous transmittance and outstanding solar modulation ability, yet progress towards the optimization of one aspect always comes at the expense of the other. Our research devotes to finding a reproducible economic solution-processed strategy for fabricating VO2-SiO2 composite films, with the aim of boosting the performance of both aspects. Compare to VO2 film, an improvement of 18.9% (from 29.6% to 48.5%) in the luminous transmittance as well as an increase of 6.0% (from 9.7% to 15.7%) in solar modulation efficiency is achieved when the molar ratio of Si/V attains 0.8. Based on the effective medium theory, we simulate the optical spectra of the composite films and the best thermochromic property is obtained when the filling factor attains 0.5, which is consistent with the experimental results. Meanwhile, the improvement of chemical stability for the composite film against oxidation has been confirmed. Tungsten is introduced to reduce the phase transition temperature to the ambient temperature, while maintain the thermochromism required for application as smart window. Our research set forth a new avenue in promoting practical applications of VO2-based thermochromic fenestration.

Two polar vessels, Akademik Shokalskiy and Xuelong, were trapped by thick sea ice in the Antarctic coastal region just to the west of 144°E and between 66.5°S and 67°S in late December 2013. This event demonstrated the rapid establishment of extreme Antarctic sea ice conditions on synoptic time scales. The event was associated with cyclones that developed at lower latitudes. Near the event site, cyclone-enhanced strong southeasterly katabatic winds drove large westward drifts of ice floes. In addition, the cyclones also gave southward ice drift. The arrival and grounding of Iceberg B9B in Commonwealth Bay in March 2011 led to the growth of fast ice around it, forming a northward protruding barrier. This barrier blocked the westward ice drift and hence aided sea ice consolidation on its eastern side. Similar cyclone-induced events have occurred at this site in the past after the grounding of Iceberg B9B. Future events may be predictable on synoptic time scales, if cyclone-induced strong wind events can be predicted.

It is well known that sodium at grain boundaries (GBs) increases the photovoltaic efficiencies of CuInSe2 and Cu2ZnSnS4 significantly. However, the mechanism of how sodium influences the GBs is still unknown. Based on the recently proposed self-passivation rule, it is found that the dangling bonds in the GBs can completely be saturated through doping the Na, thus GB states are successfully passivated. It is shown that the Na can easily incorporate into the GB with very low formation energy. Although Cu can also passivate the GB states, it requires a copper rich condition which, however, suppresses the formation of copper vacancies in the bulk and thus decreases the concentration of hole carriers, so copper passivation is practically not as beneficial as sodium. The present work reveals the mechanism about how the Na enhances the photovoltaic performance through passivating the dangling bonds in the GBs of chalcogenide semiconductors, and sheds light on how to passivate dangling bonds in GBs with alterative processes.

[1] In this paper, the trend of the South Pacific Mode Water subduction rate is assessed based on recently developed ocean and atmosphere reanalysis products for the 20th century. It is found that the subduction volume of the mode water is intensified in the 20th century. The intensification of the mode water in the subtropical gyre of the South Pacific is primarily due to the strengthening of the vertical pumping velocity dominated by the enhanced wind stress curl over the past century. In contrast, the intensification of the South Pacific Subantarctic Mode Water (SAMW) is mainly caused by a deepening of the mixed layer depths and a strengthening of the advection in warm climate. As a result, the total subduction volume of the mode water over the South Pacific is increased in the 20th century.

Monovalent, bivalent and trivalent cations of Li(+), Sn(2+), Al(3+), Fe(3+) with different values of electronegativity were designed as doped-ions to prepare cations-intercalated titanate nanobelts through ex-situ ion-exchange reaction. XRD results revealed that the d(200) values of layered TNBs decreased as the following sequence: Li-intercalated TNBs > Al-intercalated TNBs > Fe-intercalated TNBs > Sn-intercalated TNBs. The electronegativity differences between respective doped-cations and oxygen can well explain the trend of the reduction of d200 values for the synthesized layered nanobelts with different cations. The width change of nanobelts depending on intercalated cations showed similar tendency as that of d(200) excluding Sn-intercalated case. That is mostly due to the crystallization of SnO(2) nanoparticles on the nanobelts. Sn(2+) is easily crystallized to form SnO(2) nanoparticles on the surface of TNBs and being considered as unfavorable metal dopant for the present intercalation purpose. The reduction of d(200) values of the doped TNBs from that of the undoped TNBs confirms the intercalation of the doped cations into layered structure. Such simple electronegativity-difference depending mechanism may be convenient for the designing of metal ion intercalation into octahedral TiO(6) layered-oxide materials.

Both spatial and seasonal variation of turbulent diapycnal mixing in the subtropical northwestern Pacific are evaluated by employing a fine-scale parameterization method based on profiles of potential density, which are obtained from CTD measurements during our recent hydrographic surveys implemented by the China National Key Basic Research Project from 2008 to 2010 and the World Ocean Circulation Experiment. Over smooth seafloor, the value of diffusivity away from the boundary is comparable with the values observed in the stratified midlatitude ocean interior, i.e., O (10(-5) m(2) s(-1)). On the other hand, enhanced diapycnal mixing, i.e., O (10(-4) m(2) s(-1)) or larger has been found over rough topography such as the Central Basin Trough, Okidaito Ridge, the origin of the Kuroshio Current, and especially Luzon Strait, which might result from dissipation of baroclinic energy generated when barotropic tides rub over rough topography. Over flat bathymetry, mixing is probably stirred by the wind work on near inertial motions in the upper 600 m and enhanced downward propagating energy has been found in the presence of anticyclonic eddies, which points to the important role of anticyclonic eddies in enhancing the diapycnal mixing at greater depth. The diffusivity also displays a distinct seasonal variation with strong (weak) mixing corresponding to strong (weak) wind-input energy in winter (summer), which, however, is only confined to upper 600 m. This is different from the midlatitude northwestern Pacific, where seasonality of diffusivity can be found at 1500-m depth.

Arc characteristics and contact erosion of Ag, AgNi and Ag/SnO2 contacts were studied when the opening arcs were driven by transverse magnetic field. The experiments were carried out with a DC 28V/10A pure resistive load. The opening velocity varies from 10 mm/s to 50 mm/s. The transverse magnetic fields are provided by magnets and their flux density on the contact axes varies from 0 to 200 mT. The experiments were conducted in a hermetic chamber filled with pure nitrogen. Time variations of arc images were recorded by using a high speed camera. Relationships between flux density and arc parameters, such as arc durations, 2-dimensional distribution of arc positions and arc velocities, were obtained for those contacts. Contact erosion was observed and material transfer mass was measured after breaking operations. Decline ratio of the arc durations and alleviation of the mass transfer by the magnetic field no longer increase with the increment of the flux density, so the critical flux density for each contact material were finally obtained. The results can be used to design magnetic blow contacts in hermetic relays.

Effect of crystal size distribution on thermoelectric performance of Lanthanum-doped strontium titanate ( La - SrTiO 3) ceramics are investigated in this study. Thermoelectric performance measurement, coupled with microstructure studies, shows that the electrical conductivity strongly depends on the crystal size, potential barrier on the grain boundary and porosity. Meantime, because the average potential barriers height are increased along with the reduction of crystal size, the Seebeck coefficients are increased by energy filtering effect at the large number of grain boundaries. As a result, by controlling of crystal size distribution, ZT value of La - SrTiO 3 is improved.

By using molecular dynamics method, transition of Al-Co alloy from liquid to amorphous structure has been investigated theoretically. The structure parameters, pair distribution functions (PDF), bond-angle distribution functions, and Voronoi polyhedra analysis are adopted as indicators of the evolution of clusters in Al-Co alloy during the rapid cooling processes. We found that below transition temperature, the second peak of PDF curves splits into two pronounced subpeaks, while at all temperature the PDF curves gradually converge to unity at large distance. This indicates that the amorphous alloy exhibits local ordering structure and has no long-range ordering. Besides, the bond-angle distribution function predicts that the degrees in the vicinity of 63.4 and 113.4 are dominated in the system during the processes of rapid annealing, which represent that the icosahedral structures are dominant. Together with the cluster structures observed in simulation, Voronoi polyhedra analysis shows that the most popu...