Two-dimensional g-C3N4/Ca2Nb2TaO10 nanosheet composites for efficient visible light photocatalytic hydrogen evolution

Scalable g-CN nanosheet powder catalyst was prepared by pyrolysis of dicyandiamide and ammonium chloride followed by ultra-sonication and freeze-drying. Nanosheet composite that combines the g-CN nanosheets and CaNbTaO nanosheets with various ratios were developed and applied as photocatalysts for solar hydrogen generation. Systematic studies reveal that the g-CN/CaNbTaO nanosheet composite with a mass ratio of 80:20 shows the best performance in photocatalytic H evolution under visible light-irradiation, which is more than 2.8 times out-performing bare g-CN bulk. The resulting nanosheets possess a high surface area of 96\ua0m/g, which provides abundance active sites for the photocatalytic activity. More importantly, the g-CN/CaNbTaO nanosheet composite shows efficient charge transfer kinetics at its interface, as evident by the photoluminescence measurement. The intimate interfacial connections and the synergistic effect between g-CN nanosheets and CaNbTaO nanosheets with cascading electrons are efficient in suppressing charge recombination and improving photocatalytic H evolution performance

Mutual Information-Based Integrated Sensing and Communications: A WMMSE Framework

In this letter, a weighted minimum mean square error (WMMSE) empowered integrated sensing and communication (ISAC) system is investigated. One transmitting base station and one receiving wireless access point are considered to serve multiple users a sensing target. Based on the theory of mutual-information (MI), communication MI and sensing MI rate are utilized as the performance metrics under the presence of clutters. In particular, we propose an novel MI-based WMMSE-ISAC method by developing a unique transceiver design mechanism to maximize the weighted sensing and communication sum-rate of this system. Such a maximization process is achieved by utilizing the classical method -- WMMSE, aiming to better manage the effect of sensing clutters and the interference among users. Numerical results show the effectiveness of our proposed method, and the performance trade-off between sensing and communication is also validated

A hybrid TiO2–Ag nanocluster (NC) photoelectrode demonstrating unique wavelength-switchable photocurrents

Chemicals used, fabrication procedure, instrumentation, and photochemical measurements used in experimentsSupporting figures, images, and graph

Multiple resolution seismic attenuation imaging at Mt. Vesuvius

A three-dimensional S wave attenuation tomography of Mt. Vesuvius has been ob- tained with multiple measurements of coda-normalized S-wave spectra of local small magnitude earthquakes. We used 6609 waveforms, relative to 826 volcano-tectonic earthquakes, located close to the crater axis in a depth range between 1 and 4 km (below the sea level), recorded at seven 3-component digital seismic stations. We adopted a two-point ray-tracing; rays were traced in an high resolution 3-D velocity model. The spatial resolution achieved in the attenuation tomography is comparable with that of the velocity tomography (we resolve 300 m side cubic cells). We statisti- cally tested that the results are almost independent from the radiation pattern. We also applied an improvement of the ordinary spectral-slope method to both P- and S-waves, assuming that the di¤erences between the theoretical and the experimental high frequency spectral-slope are only due to the attenuation e¤ects.We could check the coda-normalization method comparing the S attenuation image obtained with the two methods. The images were obtained with a multiple resolution approach. Results show the general coincidence of low attenuation with high velocity zones. The joint interpretation of velocity and attenuation images allows us to interpret the low attenuation zone intruding toward the surface until a depth of 500 meters below the sea level as related to the residual part of solidi ed magma from the last eruption. In the depth range between -700 and -2300 meters above sea level, the images are consistent with the presence of multiple acquifer layers. No evidence of magma patches greater than the minimum cell dimension (300m) has been found. A shallow P wave attenuation anomaly (beneath the southern ank of the volcano) is consitent with the presence of gas saturated rocks. The zone characterized by the maximum seismic energy release cohincides with a high attenuation and low velocity volume, interpreted as a cracked medium

Switched photocurrent on tin sulfide-based nanoplate photoelectrodes

A new type of SnS2 nanoplate photoelectrode is prepared by using a mild wet-chemical method. Depending on the calcination temperatures, SnS2-based photoelectrodes can either retain their n-type nature with greatly enhanced anodic photocurrent density (ca. 1.2 mA cm(-2) at 0.8V vs. Ag/AgCl) or be completely converted into p-type SnS to generate approximately 0.26 mA cm(-2) cathodic photocurrent density at -0.8 V vs. Ag/AgCl. The dominance of sulfur and tin vacancies are found to account for the dramatically different photoelectrochemical behaviors of n-type SnS2 and p-type SnS photoelectrodes. In addition, the band structures of n-type SnS2 and p-type SnS photoelectrodes are also deduced, which may provide an effective strategy for developing SnS2/SnS films with controllable energy-band levels through a simple calcination treatment

Graph pangenome captures missing heritability and empowers tomato breeding

Missing heritability in genome-wide association studies defines a major problem in genetic analyses of complex biological traits(1,2). The solution to this problem is to identify all causal genetic variants and to measure their individual contributions(3,4). Here we report a graph pangenome of tomato constructed by precisely cataloguing more than 19 million variants from 838 genomes, including 32 new reference-level genome assemblies. This graph pangenome was used forgenome-wide association study analyses and heritability estimation of 20,323 gene-expression and metabolite traits. The average estimated trait heritability is 0.41 compared with 0.33 when using the single linear reference genome. This 24% increase in estimated heritability is largely due to resolving incomplete linkage disequilibrium through the inclusion of additional causal structural variants identified using the graph pangenome. Moreover, by resolving allelic and locus heterogeneity, structural variants improve the power to identify genetic factors underlying agronomically important traits leading to, for example, the identification of two new genes potentially contributing to soluble solid content. The newly identified structural variants will facilitate genetic improvement of tomato through both marker-assisted selection and genomic selection. Our study advances the understanding of the heritability of complex traits and demonstrates the power of the graph pangenome in crop breeding

Abnormal cathodic photocurrent generated on an n-type FeOOH nanorod-array photoelectrode

A simple, wet-chemical method for the synthesis of an FeOOH nanorod-array photoelectrode on fluorine-doped tin oxide (FTO) glass is reported. Nanorods of diameter about 35nm and length about 300nm have been vertically grown on an FTO substrate. Upon calcination, the FeOOH phase could be easily converted to a hematite structure while maintaining the shape of the nanorod array. An interesting abnormal cathodic photocurrent is generated on the FeOOH nanorod-array photoelectrode under illumination, which is totally different from that obtained on a calcined hematite photoelectrode under the same experimental conditions. The cathodic photocurrent density generated on the FeOOH photoelectrode can also be tuned by applying an electrochemical anodic or cathodic treatment. Detailed analysis has revealed that higher valence state Fe species in the FeOOH photoelectrode play an important role in sacrificing the photoexcited electrons for generation of the cathodic photocurrent. Comparison between the FeOOH and hematite photoelectrodes allows for a better understanding of the interplay between crystal structure, surface reactions, and photocurrent. The findings on this new abnormal phenomenon could also provide guidance for the design of new types of semiconducting photoelectrochemical devices

Transition from the Tetragonal to Cubic Phase of Organohalide Perovskite: The Role of Chlorine in Crystal Formation of CH3NH3PbI3 on TiO2 Substrates

The role of chlorine in the superior electronic property and photovoltaic performance of CH3NH3PbI(3-x)Clx perovskite has attracted recent research attention. Here, we study the impact of chlorine in the perspective of the crystal structure of the perovskite layer, which can provide important understanding of its excellent charge mobility and extended lifetimes. In particular, we find that in the presence of chlorine (PbCl2 or CH3NH3Cl), when CH3NH3PbI3 films are deposited on a TiO2 mesoporous layer instead of a planar TiO2 substrate, a stable cubic phase rather than the commonly observed tetragonal phase is formed in CH3NH3PbI3 perovskite at room temperature. The relative peak intensity of two major facets of cubic CH3NH3PbI3 crystals, (100)(C) and (200)(C) facets, can also be easily tuned, depending on the film thickness. Furthermore, compared with pristine CH3NH3PbI3 perovslcite films, in the presence of chlorine, CH3NH3PbI3 crystals grown on planar substrates exhibit strong preferred orientations on (110)(T) and (220)(T) facets

Two-dimensional g-C 3 N 4 /Ca 2 Nb 2 TaO 10 nanosheet composites for efficient visible light photocatalytic hydrogen evolution

Scalable g-C3N4 nanosheet powder catalyst was prepared by pyrolysis of dicyandiamide and ammonium chloride followed by ultra-sonication and freeze-drying. Nanosheet composite that combines the g-C3N4 nanosheets and Ca2Nb2TaO10 nanosheets with various ratios were developed and applied as photocatalysts for solar hydrogen generation. Systematic studies reveal that the g-C3N4/Ca2Nb2TaO10 nanosheet composite with a mass ratio of 80:20 shows the best performance in photocatalytic H2 evolution under visible light-irradiation, which is more than 2.8 times out-performing bare g-C3N4 bulk. The resulting nanosheets possess a high surface area of 96 m2/g, which provides abundance active sites for the photocatalytic activity. More importantly, the g-C3N4/Ca2Nb2TaO10 nanosheet composite shows efficient charge transfer kinetics at its interface, as evident by the photoluminescence measurement. The intimate interfacial connections and the synergistic effect between g-C3N4 nanosheets and Ca2Nb2TaO10 nanosheets with cascading electrons are efficient in suppressing charge recombination and improving photocatalytic H2 evolution performance.The authors would like to acknowledge the financial support from Australian Research Council through its DP and FF programs. This work was performed in part atthe Queensland node oftheAustralian National Fabrication Facility. S.T. would like to acknowledge the support from the Royal Thai Government Scholarship, Ministry of Science and Technolog