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The flow conditions of the grinding fluid during grinding are analyzed with regard to the problem of easy burns during surface profile grinding of difficult-to-machine materials, nickel-based high-temperature alloys. The CFD simulations were carried out to analyze the grinding fluid flow in the grinding zone during flat and circular profile grinding according to the gas–liquid two-phase flow VOF theory. Numerical simulations were performed using FLUENT software to analyze the pressure and volume fraction in the gas–liquid two-phase flow field under different parameters by changing the injection speed and injection position. The effects of different injection positions and injection speeds on the grinding fluid flow in the grinding zone were investigated. The study showed that the higher the injection speed of the grinding fluid, the higher the dynamic pressure of the grinding fluid on the workpiece surface and the higher the return flow rate on the grinding wheel surface; the lower the speed, the lower the dynamic pressure of the grinding fluid on the workpiece surface but the higher the return flow rate. At the same injection position, the volume fraction of grinding fluid flowing from the outlet first increases with increasing injection speed, and then tends to level off; at the same injection speed, the integral number of grinding fluid flowing from the outlet is greatest for the central injection. Thus, the optimal injection position and injection speed of grinding fluid are proposed. It provides an important reference for improving the quality of profile grinding and preventing the workpiece from being burned during grinding, and provides a basis for subsequent profile grinding tests on high-temperature alloys. [ABSTRACT FROM AUTHOR]

Enantioselective construction of molecules bearing multiple stereogenic elements is increasingly related to the synthesis of enantiopure natural products, pharmaceuticals, and functional materials. However, atom‐economical and enantioselective approaches to install multiple stereogenic elements in a small molecular template by limited chemical transformation remain challenging. We describe an organocatalytic enantioselective method for the preparation of polychiral molecules bearing four types of stereogenic elements in fused azepines via vinylidene ortho‐quinone methide (VQM)‐mediated intramolecular electrophilic aromatic substitution. This method was proved robust with a wide range of substrate scope (46–92 % yield), with excellent diastereoselectivity (>20:1 dr) and enantioselectivity achieved (up to 97 % ee). Optical properties and Ru3+‐induced fluorescence responses of these compounds suggest their potential applications in optoelectronic materials and heavy metal ion detection. [ABSTRACT FROM AUTHOR]

Enantioselective construction of molecules bearing multiple stereogenic elements is increasingly related to the synthesis of enantiopure natural products, pharmaceuticals, and functional materials. However, atom‐economical and enantioselective approaches to install multiple stereogenic elements in a small molecular template by limited chemical transformation remain challenging. We describe an organocatalytic enantioselective method for the preparation of polychiral molecules bearing four types of stereogenic elements in fused azepines via vinylidene ortho‐quinone methide (VQM)‐mediated intramolecular electrophilic aromatic substitution. This method was proved robust with a wide range of substrate scope (46–92 % yield), with excellent diastereoselectivity (>20:1 dr) and enantioselectivity achieved (up to 97 % ee). Optical properties and Ru3+‐induced fluorescence responses of these compounds suggest their potential applications in optoelectronic materials and heavy metal ion detection. [ABSTRACT FROM AUTHOR]

With a precise control of temperature, gas flow, and pressure and with sequentially increased durations for reactions, the detailed processes of catalyzing, nucleation, and growth of the SiOx nanowires were successfully traced. Especially a stepwise nonuniformity in diameter of nanowire during the growth was for the first time detected. With analysis of these detailed processes via nanocurvature and nano ripening effects, a further understanding of the vapor-liquid-solid mechanism was achieved and a novel mechanism for formation of the stepwise nonuniformity in diameter of nanowire was particularly proposed. All these will be the crucial basis for the further, accurately controlled growth of SiOx nanowires and the relevant applications. [ABSTRACT FROM AUTHOR]

Abstract New STAR measurements of two- and four-particle (c 2 {4}) azimuthal angle correlations are reported for p +Au collisions at 200 GeV and d +Au collisions from 19.6 to 200 GeV. A negative c 2 {4}, consistent with collective anisotropic flow, is observed in high multiplicity d +Au events at 62.4 and 200 GeV where the statistical significance of the data allows an analysis. A template fitting method, employed to subtract non-flow contributions to the two-particle correlations, allows the extraction of the anisotropy coefficients (ν 2) for these systems at their respective energies. The ν 2 results for different energies show a common dependence on the charged particle multiplicity density (〈dN ch /d η 〉), which provide important insight on the nature of collective behavior in small collision systems. [ABSTRACT FROM AUTHOR]

Hierarchical arrays of ZnO/Si nanowires were prepared through very convenient two-step solution method on silicon substrates. The tree-like nanowire structures showed high crystal quality, where well aligned Si nanowires were grown vertical to the substrate surface, whereas uniform assembly of branched ZnO nanowires was grown normal to the Si nanowires (backbones). Raman analysis indicated that among all the specimens having identical chemical compositions and dimensions but different forms (thin films or nanowires), Ag-decorated hierarchical arrays of ZnO/Si nanowires possessed the highest intensity peak in surface enhanced Raman scattering spectra. Such arrays demonstrated exceptional ability of detecting Rhodamine 6 G, limiting to a value as low as 1×10 −8 mol/L and an enhancement factor up to 1.5 × 10 4 . Both, experimental designing and band structure analysis indicated that electromagnetic effect of the localized surface plasmon resonance of Ag nanoparticles caused eight times enhancement, whereas chemical effect of hierarchical arrays of ZnO/Si nanowires played a more critical role in the high Raman sensitivity. Our results would be helpful to better understand the enhancement mechanisms and meanwhile, could be extended for further potential applications of hierarchical semiconducting nanowires. [ABSTRACT FROM AUTHOR]

High-resolution site index (SI) and mean annual increment (MAI) maps are desired for local forest management. We integrated field inventory, Landsat, and ecological variables to produce 30 m SI and MAI maps for the Tahoe National Forest (TNF) where different tree species coexist. We converted species-specific SI using adjustment factors. Then, the SI map was produced by ( i) intensifying plots to expand the training sets to more climatic, topographic, soil, and forest reflective classes, ( ii) using results from a stepwise regression to enable a weighted imputation that minimized the effects of outlier plots within classes, and ( iii) local interpolation and strata median filling to assign values to pixels without direct imputations. The SI (reference age is 50 years) map had an R2 of 0.7637, a root-mean-square error (RMSE) of 3.60, and a mean absolute error (MAE) of 3.07 m. The MAI map was similarly produced with an R2 of 0.6882, an RMSE of 1.73, and a MAE of 1.20 m3·ha−1·year−1. Spatial patterns and trends of SI and MAI were analyzed to be related to elevation, aspect, slope, soil productivity, and forest type. The 30 m SI and MAI maps can be used to support decisions on fire, plantation, biodiversity, and carbon. [ABSTRACT FROM AUTHOR]

Boreal fires can cool the climate; however, this conclusion came from individual fires and may not represent the whole story. We hypothesize that the climatic impact of boreal fires depends on local landscape heterogeneity such as burn severity, prefire vegetation type, and soil properties. To test this hypothesis, spatially explicit emission of greenhouse gases (GHGs) and aerosols and their resulting radiative forcing are required as an important and necessary component towards a full assessment. In this study, we integrated remote sensing (Landsat and MODIS) and models (carbon consumption model, emission factors model, and radiative forcing model) to calculate the carbon consumption, GHGs and aerosol emissions, and their radiative forcing of 2001-2010 fires at 30 m resolution in the Yukon River Basin of Alaska. Total carbon consumption showed significant spatial variation, with a mean of 2,615 g C m and a standard deviation of 2,589 g C m. The carbon consumption led to different amounts of GHGs and aerosol emissions, ranging from 593.26 Tg (CO) to 0.16 Tg (NO). When converted to equivalent CO based on global warming potential metric, the maximum 20 years equivalent CO was black carbon (713.77 Tg), and the lowest 20 years equivalent CO was organic carbon (−583.13 Tg). The resulting radiative forcing also showed significant spatial variation: CO, CH, and NO can cause a 20-year mean radiative forcing of 7.41 W m with a standard deviation of 2.87 W m. This emission forcing heterogeneity indicates that different boreal fires have different climatic impacts. When considering the spatial variation of other forcings, such as surface shortwave forcing, we may conclude that some boreal fires, especially boreal deciduous fires, can warm the climate. [ABSTRACT FROM AUTHOR]

The albedo change caused by fires and the subsequent succession is spatially heterogeneous, leading to the need to assess the spatiotemporal variation of surface shortwave forcing (SSF) as a component to quantify the climate impacts of high-latitude fires. We used an image reconstruction approach to compare postfire albedo with the albedo assuming that no fires had occurred. Combining the fire-caused albedo change from the 2001-2010 fires in interior Alaska and the monthly surface incoming solar radiation, we examined the spatiotemporal variation of SSF in the early successional stage of approximately 10 years. Our results showed that although postfire albedo generally increased in fall, winter, and spring, some burned areas could show an albedo decrease during these seasons. In summer, the albedo increased for several years and then declined again. The spring SSF distribution did not show a latitudinal decrease from south to north as previously reported. The results also indicated that although the SSF is usually largely negative in the early successional years, it may not be significant during the first postfire year. The annual 2005-2010 SSF for the 2004 fire scars was -1.30, -4.40, -3.31, -4.00, -3.42, and -2.47 W·m−2, respectively. The integrated annual SSF map showed significant spatial variation, with a mean of -3.15 W·m−2, a standard deviation of 3.26 watts per square metre (W·m−2), and 16% of burned areas having positive SSF. Our results suggest that boreal deciduous fires would be less positive for climate change than boreal evergreen fires. Future research is needed to comprehensively investigate the spatiotemporal radiative and nonradiative forcings to determine the effect of boreal fires on the climate. [ABSTRACT FROM AUTHOR]

Hydrological processes of the wetland complex in the Prairie Pothole Region (PPR) are difficult to model, partly due to a lack of wetland morphology data. We used Light Detection And Ranging (LiDAR) data sets to derive wetland features; we then modelled rainfall, snowfall, snowmelt, runoff, evaporation, the “fill-and-spill” mechanism, shallow groundwater loss, and the effect of wet and dry conditions. For large wetlands with a volume greater than thousands of cubic metres (e.g. about 3000 m3), the modelled water volume agreed fairly well with observations; however, it did not succeed for small wetlands (e.g. volume less than 450 m3). Despite the failure for small wetlands, the modelled water area of the wetland complex coincided well with interpretation of aerial photographs, showing a linear regression with R2of around 0.80 and a mean average error of around 0.55 km2. The next step is to improve the water budget modelling for small wetlands. EditorZ.W. Kundzewicz;Associate editorX. Chen CitationHuang, S.L., Young, C., Abdul-Aziz, O.I., Dahal, D., Feng, M., and Liu, S.G., 2013. Simulating the water budget of a Prairie Potholes complex from LiDAR and hydrological models in North Dakota, USA.Hydrological Sciences Journal, 58 (7), 1434–1444. [ABSTRACT FROM AUTHOR]

Abstract: In interior Alaska, wildfires change gross primary production (GPP) after the initial disturbance. The impact of fires on GPP is spatially heterogeneous, which is difficult to evaluate by limited point-based comparisons or is insufficient to assess by satellite vegetation index. The direct prefire and postfire comparison is widely used, but the recovery identification may become biased due to interannual climate variability. The objective of this study is to propose a method to quantify the spatially explicit GPP change caused by fires and succession. We collected three Landsat images acquired on 13 July 2004, 5 August 2004, and 6 September 2004 to examine the GPP recovery of burned area from 1987 to 2004. A prefire Landsat image acquired in 1986 was used to reconstruct satellite images assuming that the fires of 1987–2004 had not occurred. We used a light-use efficiency model to estimate the GPP. This model was driven by maximum light-use efficiency (Emax) and fraction of photosynthetically active radiation absorbed by vegetation (FPAR). We applied this model to two scenarios (i.e., an actual postfire scenario and an assuming-no-fire scenario), where the changes in Emax and FPAR were taken into account. The changes in Emax were represented by the change in land cover of evergreen needleleaf forest, deciduous broadleaf forest, and shrub/grass mixed, whose Emax was determined from three fire chronosequence flux towers as 1.1556, 1.3336, and 0.5098gC/MJ PAR. The changes in FPAR were inferred from NDVI change between the actual postfire NDVI and the reconstructed NDVI. After GPP quantification for July, August, and September 2004, we calculated the difference between the two scenarios in absolute and percent GPP changes. Our results showed rapid recovery of GPP post-fire with a 24% recovery immediately after burning and 43% one year later. For the fire scars with an age range of 2–17years, the recovery rate ranged from 54% to 95%. In addition to the averaging, our approach further revealed the spatial heterogeneity of fire impact on GPP, allowing one to examine the spatially explicit GPP change caused by fires. [Copyright &y& Elsevier]

Extrapolating energy fluxes between the ground surface and the atmospheric boundary layer from point-based measurements to spatially explicit landscape estimation is critical to understand and quantify the energy balance components and exchanges in the hydrosphere, atmosphere, and biosphere. This information is difficult to quantify and are often lacking. Using a Landsat image (acquired on 5 August 2004), the flux measurements from three eddy covariance flux towers (a 1987 burn, a 1999 burn, and an unburned control site) and a customized satellite-based surface energy balance model of Mapping Evapotranspiration at High Resolution with Internalized Calibration (METRIC), we estimated net radiation, sensible heat flux ( H), latent heat flux (LE), and soil heat flux ( G) for the boreal Yukon River Basin of Interior Alaska. The model requires user selection of two extreme conditions present within the image area to calibrate and anchor the sensible flux output. One is the 'hot' condition which refers to a bare soil condition with specified residual evaporation rates. Another one is the 'cold' condition which refers to a fully transpiring vegetation such as full-cover agricultural crops. We selected one bare field as the 'hot' condition while we explored three different scenarios for the 'cold' pixel because of the absence of larger expanses of agricultural fields within the image area. For this application over boreal forest, selecting agricultural fields whose evapotranspiration was assumed to be 1.05 times the alfalfa-based reference evapotranspiration as the 'cold' pixel could result in large errors. Selecting an unburned flux tower site as the 'cold' pixel could achieve acceptable results, but uncertainties remain about the energy balance closure of the flux towers. We found that METRIC performs reasonably well in partitioning energy fluxes in a boreal landscape. [ABSTRACT FROM AUTHOR]

Abstract: Silver nanoparticle arrays with 2-dimensional hexagonal arrangement were fabricated on the silicon substrates by nanosphere lithography. The silver film was deposited either by thermal evaporation or by magnetron sputtering under different conditions. The nanostructures of the achieved sphere template and the array units were characterized by scanning electron microscopy and atomic force microscopy, and were found to be anomalous under different deposition parameters. Comparative study indicated that the formation of the various 2-dimensional silver nanoparticle array structures was dominated by the thermal energy (temperature), kinetic energy and deposition direction of the deposited metal atoms as well as the size and nanocurvature of the colloidal particles and the metal clusters. [Copyright &y& Elsevier]

Abstract: Land surface change caused by fires and succession is confounded by many site-specific factors and requires further study. The objective of this study was to reveal the spatially explicit land surface change by minimizing the confounding factors of weather variability, seasonal offset, topography, land cover, and drainage. In a pilot study of the Yukon River Basin of interior Alaska, we retrieved Normalized Difference Vegetation Index (NDVI), albedo, and land surface temperature (LST) from a postfire Landsat image acquired on August 5th, 2004. With a Landsat reference image acquired on June 26th, 1986, we reconstructed NDVI, albedo, and LST of 1987–2004 fire scars for August 5th, 2004, assuming that these fires had not occurred. The difference between actual postfire and assuming-no-fire scenarios depicted the fires and succession impact. Our results demonstrated the following: (1) NDVI showed an immediate decrease after burning but gradually recovered to prefire levels in the following years, in which burn severity might play an important role during this process; (2) Albedo showed an immediate decrease after burning but then recovered and became higher than prefire levels; and (3) Most fires caused surface warming, but cooler surfaces did exist; time-since-fire affected the prefire and postfire LST difference but no absolute trend could be found. Our approach provided spatially explicit land surface change rather than average condition, enabling a better understanding of fires and succession impact on ecological consequences at the pixel level. [Copyright &y& Elsevier]

Abstract: Spatiotemporal variations of wetland water in the Prairie Pothole Region are controlled by many factors; two of them are temperature and precipitation that form the basis of the Palmer Drought Severity Index (PDSI). Taking the 196km2 Cottonwood Lake area in North Dakota as our pilot study site, we integrated PDSI, Landsat images, and aerial photography records to simulate monthly water surface. First, we developed a new Wetland Water Area Index (WWAI) from PDSI to predict water surface area. Second, we developed a water allocation model to simulate the spatial distribution of water bodies at a resolution of 30m. Third, we used an additional procedure to model the small wetlands (less than 0.8ha) that could not be detected by Landsat. Our results showed that i) WWAI was highly correlated with water area with an R2 of 0.90, resulting in a simple regression prediction of monthly water area to capture the intra- and inter-annual water change from 1910 to 2009; ii) the spatial distribution of water bodies modeled from our approach agreed well with the water locations visually identified from the aerial photography records; and iii) the R2 between our modeled water bodies (including both large and small wetlands) and those from aerial photography records could be up to 0.83 with a mean average error of 0.64km2 within the study area where the modeled wetland water areas ranged from about 2 to 14km2. These results indicate that our approach holds great potential to simulate major changes in wetland water surface for ecosystem service; however, our products could capture neither the short-term water change caused by intensive rainstorm events nor the wetland change caused by human activities. [Copyright &y& Elsevier]

Summary: Recent flood events in the Prairie Pothole Region of North America have stimulated interest in modeling water storage capacities of wetlands and their surrounding catchments to facilitate flood mitigation efforts. Accurate estimates of basin storage capacities have been hampered by a lack of high-resolution elevation data. In this paper, we developed a 0.5m bare-earth model from Light Detection And Ranging (LiDAR) data and, in combination with National Wetlands Inventory data, delineated wetland catchments and their spilling points within a 196km2 study area. We then calculated the maximum water storage capacity of individual basins and modeled the connectivity among these basins. When compared to field survey results, catchment and spilling point delineations from the LiDAR bare-earth model captured subtle landscape features very well. Of the 11 modeled spilling points, 10 matched field survey spilling points. The comparison between observed and modeled maximum water storage had an R 2 of 0.87 with mean absolute error of 5564m3. Since maximum water storage capacity of basins does not translate into floodwater regulation capability, we further developed a Basin Floodwater Regulation Index. Based upon this index, the absolute and relative water that could be held by wetlands over a landscape could be modeled. This conceptual model of floodwater downstream contribution was demonstrated with water level data from 17 May 2008. [Copyright &y& Elsevier]

Abstract: Effect of chromium interlayer deposition on 2-dimensional, periodic silver nanoparticle array structure was systematically investigated. The silver nanoparticle array was fabricated by nanosphere lithography with assembled polystyrene nanospheres being as a deposition mask. The chromium interlayer was deposited by thermal evaporation either on the nanosphere mask or directly on the silicon substrate. The structures of the achieved silver nanoparticle arrays were characterized by scanning electron microscope and were compared with that of silver nanoparticle array without the interlayer. With analysis of the anomalies among the structures the critical role of the interlayer in the periodic nanoparticle array fabrication was revealed. [Copyright &y& Elsevier]

Abstract: The arid and semi-arid sagebrush–grass ecosystem occupies a substantial portion of rangelands in the western United States. Using remote sensing techniques to map the percent of sagebrush, grass/forb, and bare ground components is necessary for forage production estimation and natural resource management over large areas. However optical data have significant deficiencies in these ecosystems because of exposed bright soil, spectrally-indeterminate vegetation, and a large dead vegetation component. Radar data also have deficiencies caused by factors such as antenna pattern calibration, local incidence angle (LIA), soil moisture, and surface roughness. With the complementary vegetation information gained from optical data and radar data, these two datasets were fused to estimate 10-m sagebrush, grass, and bare ground percent cover in the non-forested areas of Yellowstone National Park, which is a representative native western rangeland ecosystem of the US. The datasets were processed to resolve the issues of antenna pattern calibration and LIA effect. Peak green Landsat, late fall Airborne Visible and Infrared Imaging Spectrometer (AVIRIS), and Airborne Synthetic Aperture Radar (AirSAR) data were fused in this analysis. AVIRIS, Landsat, AirSAR and elevation data were used to segment the study area into two main subcategories of “pure grass” and “mixed sagebrush and grass”. Landsat Tasseled Cap Greenness (LTCG) was used to retrieve bare land and grass percentages in pure grass areas. In the areas with mixed grass and sagebrush, standardized LTCG and radar C vv were used to derive the vegetation cover percentage, and the ratio of standardized LTCG and radar L hv was further used to calculate the relative abundance of sagebrush and grass. Comparison between the field and remote sensing estimations shows the correlation coefficients were 0.838, 0.746, and 0.830 for bare land, grass, and sagebrush, respectively. When grouped into three discrete categories of “low”, “medium”, and “high”, the overall accuracies were 79.4%, 75.9%, and 77.6%, respectively. Our study shows the potential for application of global spaceborne C- and L-band radar and optical data fusion for large-area rangeland monitoring. [Copyright &y& Elsevier]

Abstract: The Coarse Woody Debris (CWD) quantity, defined as biomass per unit area (t/ha), and the quality, defined as the proportion of standing dead logs to the total CWD quantity, greatly contribute to many ecological processes such as forest nutrient cycling, tree regeneration, wildlife habitat, fire dynamics, and carbon dynamics. However, a cost-effective and time-saving method to determine CWD is not available. Very limited literature could be found that applies remote sensing technique to CWD inventory. In this paper, we fused the wall-to-wall multi-frequency and multi-polarization Airborne Synthetic Aperture Radar (AirSAR) and optical Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) to estimate the quantity and quality of CWD in Yellowstone post-fire forest ecosystem, where the severe 1988 fire event resulted in high spatial heterogeneity of dead logs. To relate backscatter values to CWD metrics, we first reduced the terrain effect to remove the interference of topography on AirSAR backscatter. Secondly, we removed the influence of regenerating sapling by quadratic polynomial fitting between AVIRIS Enhanced Vegetation Index (EVI) and different channels backscatters. The quantity of CWD was derived from P hh and P hv, and the quality of CWD was derived from P hh aided by the ratio of L hv and P hh. Two maps of Yellowstone post-fire CWD quantity and quality were produced. The calculated CWD quantity and quality were validated by extensive field surveys. Regarding CWD quantity, the correlation coefficient between measured and predicted CWD is only 0.54 with mean absolute error up to 29.1 t/ha. However, if the CWD quantity was discretely classified into three categories of “≤60”, “60–120”, and “≥120”, the overall accuracy is 65.6%; if classified into two categories of “≤90” and “≥90”, the overall accuracy is 73.1%; if classified into two categories of “≤60” and “≥60”, the overall accuracy is 84.9%. This indicates our attempt to map CWD quantity spatially and continuously achieved partial success; however, the general and discrete categories are reasonable. Regarding CWD quality, the overall accuracy of 5 types (Type 1—standing CWD ratio ≥40%; Type 2—15%≤standing CWD ratio <40%; Type 3—7%≤standing CWD ratio<15%; Type 4—3%≤standing CWD ratio <7%; Type 5—standing CWD ratio <3%) is only 40.32%. However, when type 1, 2, 3 are combined into one category and type 4 and 5 are combined into one category, the overall accuracy is 67.74%. This indicates the partial success of our initial results to map CWD quality into detailed categories, but the result is acceptable if solely very coarse CWD quality is considered. Bias can be attributed to the complex influence of many factors, such as field survey error, sapling compensation, terrain effect reduction, surface properties, and backscatter mechanism understanding. [Copyright &y& Elsevier]

Two new coordination polymers, {[Co(btmb)2(H2O)2] · (Fc(SO3)2)}n (1) and {[Cd(bbbm)(H2O)4] · (p-FcC6H4SO3)2(CH3OH)}n (2) (Fc = ferrocene; btmb = 1,4-bis(triazol-1-ylmethyl)benzene); bbbm = 1,1'-(1,4-butanediyl)bis-1H-benzimidazole), were synthesized as cocrystals and characterized by single crystal X-ray diffraction, elemental analysis and IR spectrum. In 1, two btmb molecules link Co(II) ions into one 1D double-stranded chain of loops, and these chains are bridged by [image omitted] ligands through H-bonds, resulting in an infinite 2D sandwich-type network. In 2, two adjacent Cd(II) ions are interconnected by bbbm to generate a 1D zigzag chain structure, and [image omitted] squeezes like a wedge into the adjacent chains, further being assembled by O-H ··· O hydrogen bonds and π-π stacking interactions to form a 2D supramolecular network. [ABSTRACT FROM AUTHOR]

Abstract: Molecular vibrations of the polycrystalline Nd2−x Sr x CoO4 are systematically characterized by powdered x-ray diffraction, Raman scattering and infrared spectra at different dopings as well as at different temperatures. Structural refinements reveal that all the specimens crystallize in the K2NiF4 structure with space group as is also confirmed by the phonon bands of Raman scattering and infrared transmittance. The frequency shifts of the phonon bands are found to be very well consistent with the elongation and/or contraction of the bond lengths. Moreover, for Nd0.75Sr1.25CoO4, the phonon bands of the Raman active modes seem to retrace the evolutions of magnetic and structural temperature. [Copyright &y& Elsevier]

Commonly, an elusive intermediate is generated from a precursor and then trapped and consumed in a reaction. Vinylidene ortho‐quinone methides (VQMs) have been demonstrated as transient axially chiral intermediates in asymmetric catalysis due to their orthogonal π‐bonds forming an allene motif. The current understanding of VQMs is primarily based on time‐resolved absorption, trapping experiments and computational studies. Herein, we report the first isolation and comprehensive characterization of a VQM, including crystallographic analysis. The disturbed aromaticity of the VQM led to its high reactivity as an electrophile or a 4π‐component capable of asymmetric dearomatization of an electron‐deficient phenyl group. Notably, the VQM could be isolated in enantiomerically enriched form, and the subsequent transformation was stereospecific, indicating that the generation of the VQM was involved in the enantiodetermining step. This study paves the way for the direct application of VQMs as starting materials. [ABSTRACT FROM AUTHOR]

Commonly, an elusive intermediate is generated from a precursor and then trapped and consumed in a reaction. Vinylidene ortho‐quinone methides (VQMs) have been demonstrated as transient axially chiral intermediates in asymmetric catalysis due to their orthogonal π‐bonds forming an allene motif. The current understanding of VQMs is primarily based on time‐resolved absorption, trapping experiments and computational studies. Herein, we report the first isolation and comprehensive characterization of a VQM, including crystallographic analysis. The disturbed aromaticity of the VQM led to its high reactivity as an electrophile or a 4π‐component capable of asymmetric dearomatization of an electron‐deficient phenyl group. Notably, the VQM could be isolated in enantiomerically enriched form, and the subsequent transformation was stereospecific, indicating that the generation of the VQM was involved in the enantiodetermining step. This study paves the way for the direct application of VQMs as starting materials. [ABSTRACT FROM AUTHOR]

Wide bandgap semiconductor-based photocatalysts are usually limited by their low solar energy conversion efficiency due to their limited absorption solar wavelength, their rapid surface recombination of the photogenerated electron–hole pairs, and their low charge-carrier mobility. Here, we report a novel stepwise solution synthesis for achieving a new photocatalytic core–shell consisting of a titanate nanowire/reduced graphene oxide shell (or titanate/rGO) 1D-nanocomposite. The new core–shell nanocomposite maximized the specific surface area, largely reduced the charge transfer resistance and reaction energy barrier, and significantly improved the absorption of visible light. The core–shell nanocomposites' large on/off current ratio and rapid photo-responses boosted the photocurrent by 30.0%, the photocatalysis rate by 50.0%, and the specific surface area by 16.4% when compared with the results for the pure titanate nanowire core. Our numerical simulations support the effective charge separation on the new core–shell nanostructure, which can help further advance the novel photocatalysis. [ABSTRACT FROM AUTHOR]

Fault diagnosis is becoming increasingly important in improving the reliability of power electronic devices. The research in this paper focuses on the issue of the faulty operation that can occur after partial IGBT open-circuit faults in three-phase PWM rectifier circuits. To promptly and effectively diagnose faults and to determine their locations, a fault diagnosis method based on transient characteristics and random forest classification is proposed. First, the characteristics of single and double IGBT open-circuit faults in three-phase PWM rectifier circuits are analyzed. It is discovered that these faults do not immediately manifest. Instead, they exhibit fault characteristics in the corresponding time sequence. Then the random forest classifier is trained using transient fault samples from the three-phase PWM rectifier circuit. Finally, generalized testing is performed on data that was not involved in the training process, with an accuracy rate of over 98%. The use of frequency distribution graphs for visual analysis of the diagnostic results solves the problem of diagnosing multiple IGBT open-circuit faults. [ABSTRACT FROM AUTHOR]

Undersea optical communication (UOC) has been considered as the most potential next‐generation underwater wireless communication technology for ocean exploration. Photodetector is the essential component in UOC system, however, the harsh undersea environment like light attenuation and seawater corrosivity restricts the applications of conventional photodetectors. Herein, a novel natural‐electrolyte self‐powered photoelectrochemical (PEC) photodetector based on core‐shell structured Cu@GaN nanowires (NWs) network is demonstrated and direct utilization of seawater. High quality GaN shell is encapsulated on the Cu NWs network through Ga‐coating and high temperature nitridation processes. A Schottky junction along radial direction has formed at the Cu/GaN interface due to the outward diffusion of Cu into the GaN layer. Such a structure provides narrowed band detection on blue light as well as efficient carrier separation. A self‐powered undersea PEC photodetector is designed with a mini‐pipes connected device chamber, which allows direct indrawing of seawater and blue channel light communication (458 nm). This photodetector works stably for UOC in both shallow and deep‐sea conditions in Pacific Ocean area. It shows a high responsivity up to 5.04 mA W−1 and rapid response time of 0.68 ms. This photodetector can be easily integrated to marine equipment without waterproof packaging for the future energy‐saving UOC. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, new measurements of anisotropic flow for identified particles such as pions and protons in Cu + Au collisions at and U + U collisions at are reported. The anisotropic flow is studied as a function of and centrality in these two collision systems. In ultra-central U + U collisions (0–2% centrality), of protons shows a weak dependence for . A positive for charged pions is observed for with respect to the first-order event plane, the angle of which is determined by the Au-going spectators. The scaling of identified particle with the number of valence quarks has been observed in these two collision systems, with the transverse kinetic energy. [Copyright &y& Elsevier]

Hybrid piezo/triboelectric nanogenerators (H‐P/TENGs) are developed to compensate the drawbacks of a single nanogenerator by synergizing high triboelectric output voltage and piezoelectric output current in continuous contact‐separation cycles. In particular, piezoelectric zinc oxide (ZnO) has been widely used due to its excellent orientation along the c‐axis and tunable growth structures. Herein, various growth structures of ZnO, unoriented, oriented, and hierarchical structures, are incorporated in H‐P/TENGs, enhancing their power densities from 6 to 17 times. Particularly, oriented ZnO nanorod/PVA (ZnR) achieves a maximum power density of 15.9 W m−2 (≈17‐fold increment compared to pristine PVA). The highly oriented ZnO growth along the c‐axis enables large deformation upon a vertical compression, subsequently generating a large piezoelectric polarization. Moreover, the enhancement mechanism via piezoelectric polarization is elucidated using a modified overlapped electron cloud model supported with Kelvin probe force microscopy measurements. The polarization of ZnO nanocomposites enlarges the difference in the highest electron energies (ΔE) between the two triboelectric layers, driving more electrons to transfer during contact electrification, thereby enriching their surface charge densities. This study highlights the significance of growth structure control in maximizing the piezoelectric responses of ZnO, consequently improving the output performances of H‐P/TENGs. [ABSTRACT FROM AUTHOR]

• MoS 2 NTs in different shell thicknesses were constructed on FTO substrates. • MoS 2 NTs overcame the aggregation and enabled multiple refraction of light. • MS05 array owned the largest kinetic constant of 5.516 × 10 − 3 mi n − 1 c m − 2 . • The dye absorption, excitation and recombination dominated catalytic activity. Light trapping based on nanostructure has emerged as an effective method to improve light absorption of the photocatalytic devices. Herein, molybdenum disulfide nanotube arrays with different wall thicknesses were successfully synthesized by changing reactant concentration from 50 % to 150 %. The nanotubes overcame aggregation of the nanosheets, offered multiple scattering centers and enabled multiple refraction of light, leading to excellent light harvest in the visible range and molecule absorption efficiency as high as 21.0 %. The photodegradation efficiency of methylene blue as catalyzed by the nanotubes was modulated by the wall thickness, in which the highest degradation efficiency of 69.6 % and the largest kinetic constant of 5.516 × 10 − 3 mi n − 1 · c m − 2 were achieved for the thinnest wall. The analysis revealed that the photocatalytic activity of the nanotube arrays was dominated by the dye absorption, environment, light excitation and charge recombination, which would provide structural design for their applications in optoelectronics and photocatalysis. [ABSTRACT FROM AUTHOR]

This study investigates the effect of extended laminectomy (EL) on spinal cord injury (SCI) caused by spinal shortening, and further, the timing and the optimal length of removal. Dogs received spinal column shortening at T13 segment, following which the control group underwent regular laminectomy while other groups underwent laminectomy with an additional 1-lamina length removed 6h after shortening ("1-lamina EL 6 h"), an extra 1.5-lamina length resected at 6 h or 12 h after shortening ("1.5-lamina EL 6 h" and "1.5-lamina EL 12 h"), and an extra 2-lamina length removed at 6 or 12 h after shortening ("2-lamina EL 6 h" and 2-lamina EL 12 h"), respectively. Somatosensory evoked potential (SSEP) and neurological function were recorded periodically; spinal cord blood flow (SCBF) and nerve cell apoptosis were detected. The results showed that resection of an additional 1-lamina length appeared inadequate to relieve the sharp kinking of the spinal cord, whereas the kinking disappeared with an additional 2-lamina length resection. The "1-lamina EL 6 h" and "1.5-lamina EL 12 h" groups showed no significant differences from the control in latency of SSEP, SCBF, hindlimb function and apoptosis. By contrast, significant recovery of SSEP, SCBF and hindlimb function as well as reduction of apoptosis were presented in other three groups. The "2-lamina EL 6 h" group, in particular, showed the most prominent recovery. In conclusion, an additional resection of two laminae at 6 h after shortening showed the best effect in alleviating SCI. Timely and adequately extended laminectomy could be a potential therapeutic strategy for SCI attributable to spinal shortening. [ABSTRACT FROM AUTHOR]

Spatially explicit precipitation data are required in the research of hydrology, agriculture, ecology, and environmental sciences. In this study, two established techniques of local ordinary linear regression (OLR) and geographically weighted regression (GWR) and two new local hybrid interpolation techniques of local regression-kriging (LRK) and geographically weighted regression kriging (GWRK) were compared to predict the spatial distribution of mean annual precipitation of China. Precipitation data from 684 meteorological stations were used in the analysis, and a stepwise regression analysis was used to select six covariates, including longitude, latitude, elevation, slope, surface roughness, and river density. The four spatial prediction methods (OLR, GWR, LRK, and GWRK) were implemented with local regression techniques with different number of neighbors (50, 100, 150, and 200). The prediction accuracy was assessed at validation sites with the root mean squared deviation, mean estimation error, and R-square values. The results showed that LRK outperforms OLR and GWRK outperforms GWR, indicating that adding the kriging of regression residuals can help improve the prediction performance. GWRK gives the best prediction but the accuracy of estimation varies with the number of neighborhood points used for modeling. Although LRK is outperformed by GWRK, LRK is still recommended as a powerful and practical interpolation method given its computation efficiency. However, if LRK and GWRK are used to extrapolate prediction values, post-processing in the areal interpolation will be needed. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 NTs and ZnO/MoS 2 NRs in different lengths were constructed normal to the substrates. • The NTs enhanced Raman intensity with a detection limit of 5 × 10−7 M than 1 × 10−6 M for the NRs. • The NTs exhibited faster self-cleaning for a recyclable substrate. • The mechanisms for the NTs outperforming the NRs were illustrated. Structure and heterojunction of substrates are widely regarded as critical factors to improve Raman detection and recyclibility, but the exact roles are rarely explored for the mixed contributions. Herein, the arrays of ZnO/MoS 2 coaxial nanorods (NRs) and MoS 2 nanotubes (NTs) were successfully constructed for the surface-enhanced Raman scattering (SERS). The influences of NR and NT length on the morphology, light absorption and emission, as well as SERS performance were systematically investigated. Both the arrays grown for 40 min displayed optimal SERS performance, in which MoS 2 NT array owned stronger enhancement with a detection limit of 5 × 10−7 M than that of 1 × 10−6 M for ZnO/MoS 2 NR array. The NTs also effectively enhanced photocatalysis, in which rhodamine 6G pollutant was completely degraded within 140 min under ultraviolet light, surpassing that by the NRs. The analysis revealed that band alignment and structure characteristic of the specimens played critical roles in the spectral enhancement and self-cleaning, while the nanostructure surpassed heterojunction as it supplied void interior for extending light propagation and more contact area for adsorbing pollutants. These results would contribute to a better understanding of the Raman enhancement and could be extended to the design of SERS substrates to harness their potential application. [ABSTRACT FROM AUTHOR]

ABSTRACT The estimation of ice/snow accumulation is of great significance in quantifying the mass balance of ice sheets and variation in water resources. Improving the accuracy and reducing uncertainty has been a challenge for the estimation of annual accumulation over the Greenland ice sheet. In this study, we kriged and analyzed the spatial pattern of accumulation based on an observation data series including 315 points used in a recent research, plus 101 ice cores and snow pits and newly compiled 23 coastal weather station data. The estimated annual accumulation over the Greenland ice sheet is 31.2 g cm−2 yr−1, with a standard error of 0.9 g cm−2 yr−1. The main differences between the improved map developed in this study and the recently published accumulation maps are in the coastal areas, especially southeast and southwest regions. The analysis of accumulations versus elevation reveals the distribution patterns of accumulation over the Greenland ice sheet. [ABSTRACT FROM AUTHOR]

Abstract: The density of lodgepole pine (Pinus contorta) sapling regeneration was mapped in areas burned during the 1988 wildfires across Yellowstone National Park (YNP), Wyoming, USA. Hyperspectral image analysis and field measurements were combined across the entire YNP extent. Airborne Visible Infrared Imaging Spectrometer (AVIRIS) image data from 2006 were used to compute ten different vegetation indices (VI). The ten VIs were combined to build multiple regression models for predicting and mapping post-fire sapling density. Four different forms of regression modeling were applied to derive the highest possible prediction accuracy (correlation coefficient of R 2 =0.83). Pine sapling regeneration 19years after large-scale wildfires showed a high level of variability in patch density (ranging from 14/100ha to 57/100ha), whereas sapling density measured previously from the first decade following wildfire was more uniform (10/100ha to 21/100ha). The ecosystem-level clumpiness index showed major shifts in aggregation of different sapling density classes, and was consistent with an overall decrease in estimated sapling density of nearly 50% between 1998 and 2007. This analysis revealed important succession patterns and processes in post-fire forest regeneration for the Greater Yellowstone Area (GYA). [Copyright &y& Elsevier]

Abstract: The diameter of a single-walled carbon nanotube shrunk at an increasingly faster rate under electron beam irradiation in a transmission electron microscope. The relationship between the radius of the single-walled carbon nanotube and the irradiation time demonstrates that the shrinkage is much faster than that predicted by current simulations. The results indicate that a curvature effect on the nanoscale and an energetic beam-induced soft mode and lattice instability effect, which were underestimated or neglected in the existing simulations are the primary driving force for the shrinkage. [Copyright &y& Elsevier]

Abstract: The Ru-doped Ruddlesden–Popper (RP)-type compounds Sr3Fe2−x Ru x O7 (, 0.3, 0.6, 1.0 and 1.4) were synthesized and checked by X-ray diffraction (XRD). The doping dependencies of unit cell parameters, resistivity () and magnetization were studied. Further, hysteresis measurements were done on the sample . Resistance measurements indicate that all the samples are insulators and electric transport properties fit the two-dimensional variable range hopping (VRH) model very well. Magnetism measurements show that a spin-glass state exists in all the measured samples when the temperature is lower than about 25 K. The temperature dependencies of the inverse molar magnetic susceptibility indicate that weak ferromagnetism occurs at a much higher temperature than that of glassy transition. [Copyright &y& Elsevier]

• The band positions of the semiconductor crystals in nanoscale experience a significant shift when they are joined together. • The introduction of Au nanoparticles into the heterojunction interface instigates an additional band offset. • Compared to Si/ZnO array, Si/Au/ZnO array decreases resistance from 85 to 52 Ω and improves photocurrent from 0.5 to 4.0 µA for the superior band alignment. • The reaction rate of Si/Au/ZnO array is nearly twice that of Si/ZnO array and 2.53 times that of Si array. • The change of band position and band alignment by the interfacial regulation can be applied to other semiconductor heterostructures. The exotic performances of semiconductor heterostructures are generally ascribed to the band alignment and band bending at the heterojunction interface for the built-in potential. Herein, theoretic computations and experiments reveal for the first time that the band positions of Si and ZnO experience a significant shift when they are joined together. The introduction of Au nanoparticles into this interfacial layer matrix instigates an additional band offset, leading to the change from type-I to type-II band alignment. Compared to the binary architecture, the superior band alignment of the ternary architecture augments light absorption, concurrently suppressing photoluminescence and reducing resistance from 85 to 52 Ω. Moreover, a substantial improvement in photocurrent is achieved, increasing from 0.5 to 4.0 µA, alongside a significant elevation in photocatalytic activity from 1.90 × 10−3 to 3.67 × 10−3 min−1, indicating potential of the Si/Au/ZnO heterostructure as a promising candidate in optoelectronics and photocatalysis. The current work highlights the band offset and interfacial regulation of the semiconductor heterostructures, which diverges from the band bending for the built-in potential and can be extended to design heterogeneous semiconductor nanomaterials with suitable band alignment for their potential applications. Band offset and interfacial regulation of the core-shell Si/Au/ZnO nanowire array lead to the enhanced photoelectrochemical and photocatalytic performances. [Display omitted] [ABSTRACT FROM AUTHOR]

The hollow NT with a built-in electric field at the heterogeneous semiconductor shell expanded curvature effect and generated light diffraction in the inner wall that enhanced light absorption and improved charge transfer and photocatalytic activity. [Display omitted] • MoS 2 and its heterogeneous NT arrays were synthesized on FTO substrates in a vertical alignment. • The hollow NT with the heterogeneous semiconductor shell expanded curvature effect and generated light diffraction in the inner wall that enhanced light absorption and improved charge transfer and photocatalytic activity. • The MoS 2 /ZnO/Ag 2 S array owned the best catalytic performance with efficiencies of 68.9 % and 78.1 % in 30 min under visible and UV light, respectively. • A built-in electric field at the interface pointing from MoS 2 to ZnO induced a type-II band alignment that promoted photocatalytic performance. Nanotubes are unique structures capable of producing light diffraction on their inner wall, amplifying curvature effect, and enhancing light excitation. These characteristics are of paramount importance in the fields of the optoelectronic and photocatalytic materials. In this study, MoS 2 and its heterogeneous nanotube arrays were synthesized on FTO substrates in a vertical alignment. The hollow structure of these nanotube arrays was found to significantly enhance light absorption efficiency. The core–shell MoS 2 /ZnO resulted in strong electric interaction at the interface, leading to a reduced bandgap in MoS 2. Being catalysts for the degradation of dye molecules, all the nanotube arrays achieved larger photocatalytic efficiency than that of the nanowire arrays with identical components. The ternary MoS 2 /ZnO/Ag 2 S array owned the best catalytic performance for the degradation of methylene blue, with efficiencies of 68.9 % and 78.1 % in 30 min under visible and UV light, respectively. Both experimental and theoretical analyses revealed the presence of a built-in electric field at the interface, directing from MoS 2 to ZnO. This induced a type-II band alignment that promoted photocatalytic performance. This study highlights the exceptional optoelectronic conversion properties and photocatalytic activity of nanotube heterojunctions, holding significant implications for the design of semiconductor devices. [ABSTRACT FROM AUTHOR]

Purpose: To determine the safe range of shortening the spinal column at middle thoracic spine and to observe the changes in blood-spinal cord barrier (BSCB), microglia/macrophage activation and inducible nitric oxide synthase (iNOS) activity after shortening-induced spinal cord injury.Methods: Dogs were allocated to four groups. Group A (control) underwent laminectomy of T7 without shortening the spinal column. Groups B, C and D had 1/3, 1/2, and 2/3 of T7 resected, respectively, followed by spinal shortening. Somatosensory evoked potential (SSEP) and hind-limb function were recorded periodically for 14 days after operation. Spinal cord blood flow (SCBF) and BSCB were detected at the acute phase of shortening. Microglia/macrophage reactions and iNOS activity were observed by immunohistochemistry.Results: Shortening of 1/3 of a vertebral height caused no significant changes in SSEP and hind-limb function after operation, whereas shortening of 1/2 of the height caused SSEP abnormality and paraparesis, and severe neurologic deficit of hind-limb was observed when the shortening reached 2/3 of the height. SCBF increased temporarily and showed a trend of recovery when the shortening was within 1/2 of a vertebral segment height. When it reached 1/2 or 2/3 of the height, SCBF at 6 h post-operation was 86.33% or 74.95% of the baseline, and an increasing BSCB permeability was observed. In the subsequent 7 days, obvious activation of macrophage and increased number of iNOS-positive cells were observed.Conclusion: It is safe to shorten the spinal cord within 1/3 of a vertebral height in middle thoracic spine under two-segment laminectomy in canine. The BSCB disruption, macrophage activation, and increased iNOS activity were observed in the acute phase of the injury. These slides can be retrieved under Electronic Supplementary Material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell Si/TiO 2 nanowires were synthesized vertically on silicon substrate. • The heterostructure owned a wide spectral absorption with large photocurrent. • The catalytic efficiency of the sample was 86.82% in 1 h with good stability. • The excited charges were effectively separated by the internal electric field. Semiconductor photocatalysts can eliminate organic pollutants completely, but the poor utilization of solar energy and rapid recombination of photogenerated electron-hole pairs have become a vital obstacle for their widespread application. Herein Si/TiO 2 nanowire arrays with core–shell structures were fabricated by metal-assisted chemical etching and atomic-layered deposition. The physical properties and photocatalytic performance of the specimens were tested and compared with pristine Si nanowire arrays. The specimens showed perfect light absorption. The photoluminescence was generally depressed by the shell layer, and the photocurrent and photocatalytic efficiency of Si/TiO 2 were improved by 297 and 2 times respectively in contrast to Si. The magnitude of the photocurrent and photocatalytic activity could be modulated by the etching period, in which an ideal etching time of 2 h produced the highest photocatalytic performance. The high efficient photocatalysis of the heterostructure was well illustrated by the Z-scheme band alignment and large specific surface area. [ABSTRACT FROM AUTHOR]

High-Responsivity Natural-Electrolyte Undersea Photoelectrochemical Photodetector with Self-Powered Cu@GaN Nanowires Network (Adv. Funct. Keywords: copper nanowires; photodetectors; self-powered devices; underwater optical communication EN copper nanowires photodetectors self-powered devices underwater optical communication 1 1 1 07/21/23 20230718 NES 230718 B Underwater Optical Communication b In article 2302872, Duanjun Cai, Shengli Huang, and co-workers propose a novel type electrolyte-free and self-powered photoelectrochemical photodetector with Cu@GaN nanowires network for undersea optical communication. Copper nanowires, photodetectors, self-powered devices, underwater optical communication. [Extracted from the article]

Timely and accurate knowledge of species-level biomass is essential for forest managers to sustain forest resources and respond to various forest disturbance regimes. In this study, maps of species-level biomass in Chinese boreal forests were generated by integrating Moderate Resolution Imaging Spectroradiometer (MODIS) images with forest inventory data using k nearest neighbor ( kNN) methods and evaluated at different scales. The performance of 630 kNN models based on different distance metrics, k values, and temporal MODIS predictor variables were compared. Random Forest (RF) showed the best performance among the six distance metrics: RF, Euclidean distance, Mahalanobis distance, most similar neighbor in canonical correlation space, most similar neighbor computed using projection pursuit, and gradient nearest neighbor. No appreciable improvement was observed using multi-month MODIS data compared with using single-month MODIS data. At the pixel scale, species-level biomass for larch and white birch had relatively good accuracy (root mean square deviation < 62.1%), while the other species had poorer accuracy. The accuracy of most species except for willow and spruce was improved up to the ecoregion scale. The maps of species-level biomass captured the effects of disturbances including fire and harvest and can provide useful information for broad-scale forest monitoring over time. [ABSTRACT FROM AUTHOR]

The extraordinary optical transmission and Faraday effects of the bilayer heterostructure consisting of a metallic film perforated with subwavelength hole arrays and a uniform dielectric film magnetized perpendicular to its plane were systematically studied by three-dimensional finite-difference time-domain method. Results of the calculation found that for the magneto-plasmonic crystals under polarized incident light with transverse magnetic mode, the resonant transmittance reached 36.9%, the Faraday rotation acquired 1.216°, and the ellipticity got a positive value of 0.840. The value of Faraday rotation and ellipticity is respectively 15.2 and 93.3 times enhancement of the 0.08° and −0.009 of the bare BIG film at the wavelength. In the transverse electric mode, the Faraday effects of the systems also had a large enhancement in contrast to the bare magnetic film. The magneto-optical effects of the systems could be manipulated by polarization mode of incident light, geometry of perforated subwavelength hole arrays, and thickness of metallic and magnetic films. Evolution of the magneto-optical properties on the structural parameters was also analyzed. Possible mechanisms underlying the extraordinary phenomena were profoundly discussed. All these results indicated that the systems could find potential applications in magneto-optical devices such as data storages, sensors, and telecommunications. [ABSTRACT FROM AUTHOR]

Branched ZnO/Si nanowire arrays have been synthesized by integration of metal-assisted chemical etching and hydrothermal growth. Experiments for different etching duration and hydrothermal growth time were carried out to investigate their effect on the final morphology of the heterogeneous material as well as its photoluminescence and antireflectance. The results demonstrated that the Si nanowires got longer with extending etching period, on which the branched ZnO nanowires were shorter in length and smaller in diameter in the set time period. The branched ZnO nanowires became longer and gradually filled up the interval among Si nanowires with prolonging hydrothermal growth. The emission spectra indicated that the nanostructure became better with less defects and impurities for the long Si nanowires. The diffuse reflectance spectra of the ZnO/Si nanowires showed an optimal growth period for the reflectivity lower than 4% in the visible region. In this article, possible mechanisms for the nanowire arrays growth and optical properties and their evolution were also discussed, which might provide guidance for the architecture and application of the heterogeneous tree-like nanowire arrays. [ABSTRACT FROM AUTHOR]

Regioselective modification is an effective approach to synthesize polysaccharides with different structure features and improved properties. In this study, regioselective sulfation of Artemisia sphaerocephala polysaccharide (S RS ASP) was prepared by using triphenylchloromethane (TrCl) as protecting precursor. The decrease in fractal dimension ( d f ) values (1.56–2.04) of S RS ASP was observed in size-exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS) analysis. Compared to sample substituted at C-6, S RS ASP showed a more expanded conformation of random coil, which was attributed to the breakup of hydrogen bonds and elastic contributions. Circular dichroism (CD), methylene blue (MB) and congo red (CR) spectrophotometric method and atomic force microscopy (AFM) results confirmed the conformational transition and stiffness of the chains after sulfation. S RS ASP exhibited enhanced antioxidant activities in the DPPH, superoxide and hydroxyl radical scavenging assay. Sulfation at C-2 or C-3 was favorable for the chelation which might prevent the generation of hydroxyl radicals. It concluded that the degree of substitution and substitution position were the factors influencing biological activities of sulfated polysaccharides. [ABSTRACT FROM AUTHOR]

Plasmonic properties of the Ag nanocaps were analyzed by the finite-difference time-domain method, in addition to the fabrication and sensor application of the two-dimensional Ag nanocap arrays. The thickness limitation for the light penetration of the nanocaps was revealed. The evolution of the plasma modes with the shell thickness and structure of the nanocaps was illustrated. The hemisphere nanocap was found to own the strongest absorption intensity and field enhancement. The sensing ability of the fabricated Ag hemisphere nanocap arrays was evaluated by the Raman spectrum of the rhodamine 6G and methylene blue molecules. The ordered arrays displayed improved light absorption with intense plasmon coupling, resulting in the strong surface-enhanced Raman scattering with an enhanced factor 15 folds of the nanosphere arrays, which suggested that the metal nanocaps might be promising for biochemical sensor application. The ordered nanocaps owned strong light absorption and confined electric field around with enormous plasmon coupling, resulting in the improved surface-enhanced Raman scattering with an enhanced factor 15 folds of the ordered nanospheres. [Display omitted] • A certain thickness limitation for the light penetration of the Ag nanocaps was revealed. • The evolution of the plasma modes with the shell thickness of the caps was illustrated. • The development of the plasma modes with the cap structure was illustrated. • The Ag nanocap arrays confined electric field around the nanocaps with strong plasmon coupling. • The Ag nanocap arrays achieved an enhanced factor as large as 15 folds of the Ag/PS nanosphere arrays. [ABSTRACT FROM AUTHOR]

Abstract: Lectin-like oxidized low-density lipoprotein (oxLDL) receptor-1 (LOX-1) was originally identified as a receptor for oxLDL predominantly expressed in endothelial cells. Recently up-regulation of LOX-1 has been implicated in oxidative stress and cell apoptosis in many cell types. However, LOX-1 expression in neurons or regulation of neuronal apoptosis by LOX-1 has not been reported. To investigate the possible roles of LOX-1 in hypertension induced brain damage, we examined the distribution of LOX-1 in cortex and hippocampus and compared its expression in 32-week-old SHR and WKY rats. Immunofluorescence revealed that LOX-1 positive cells were located principally at the cortex involved in sensory information processing and were mainly expressed in neurons. We also found up-regulated mRNA expression of LOX-1, Bax and caspase-3 and down-regulated mRNA expression of Bcl-2 in SHR group. Compared with WKY group, SHR group showed increased LOX-1 positive cells and TUNEL positive cells. Furthermore, double-labeling method indicated that LOX-1 expression was colocalized with TUNEL positive cells, which means that LOX-1 expression was involved in hypertension related cell apoptosis. These findings indicated that LOX-1 expression was up-regulated in the cortex of SHR and its expression has implication in neuronal apoptosis. Elevated Bax/Bcl-2 ratio may be involved under this event. [Copyright &y& Elsevier]

We present and describe a modeling and analysis framework for monitoring protected area (PA) ecosystems with net primary productivity (NPP) as an indicator of health. It brings together satellite data, an ecosystem simulation model (NASA–CASA), spatial linear models with autoregression, and a GIS to provide practitioners a low-cost, accessible ecosystem monitoring and analysis system (EMAS) at landscape resolutions. The EMAS is evaluated and assessed with an application example in Yellowstone National Park aimed at identifying the causes and consequences of drought. Utilizing five predictor covariates (solar radiation, burn severity, soil productivity, temperature, and precipitation), spatio-temporal analysis revealed how landscape controls and climate (summer vegetation moisture stress) affected patterns of NPP according to vegetation functional type, species cover type, and successional stage. These results supported regional and national trends of NPP in relation to carbon fluxes and lag effects of climate. Overall, the EMAS provides valuable decision support for PAs regarding informed land use planning, conservation programs, vital sign monitoring, control programs (fire fuels, invasives, etc.), and restoration efforts. [Copyright &y& Elsevier]

• Type-I-C 46 , Type-II-C 34 and Type-H-C 34 carbon clathrates show distinct anisotropy in their tensile Young's moduli and ideal tensile/shear strengths, but isotropy in the shear Young's moduli. • Maximum ideal tensile strength of carbon clathrates can exceed that of heavyweight diamond under <111> directional load, and shear Young's moduli are comparable to that of diamond • Those carbon clathrates are intrinsically indirect semiconductors, and their electronic properties can be greatly dictated by mechanical tension and shear strains. Clathrates are fully- sp 3 cage-like three dimensional (3D) structures that offer unique mechanical and electronic properties. Here, the mechanical properties of Type-I-C 46 , Type-II-C 34 and Type-H-C 34 carbon clathrates under uniaxial and shear loads are examined by means of ab initio calculations. It is predicted that those carbon clathrates show distinct anisotropy in their ideal tensile/shear strengths and critical tensile/shear strains, but isotropy in the shear Young's moduli. Intriguingly, their maximum ideal tensile strengths exceed that of heavyweight diamond under <111> directional load, and their shear Young's moduli are comparable to that of diamond. Those carbon clathrates show distinct deformability in their critical load-bearing bond configurations, resulting in their distinct mechanical properties. Moreover, all investigated carbon clathrates are intrinsically indirect semiconductors, and their electronic properties can be greatly tuned by tension and shear strains. As a consequence, carbon clathrates can be potentially utilized as lightweight strong engineering structures and in electromechanical devices. [Display omitted] [ABSTRACT FROM AUTHOR]