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Near‐infrared phosphor‐converted light‐emitting diodes (NIR‐pc‐LEDs) are superior to traditional NIR‐LEDs in spectral modulation, volume, and cost, and their optoelectronic properties are dominantly controlled by the NIR phosphors, which thus boosts the search for high efficiency and broadband NIR phosphors. In this work, we attempt to realize ultra‐broadband NIR phosphors by doping Cr3+ in self‐emitting SrHfO3 with a weak crystal field. Dual emission bands centered at 770 (host) and 1000 nm (Cr3+) are observed, leading to a wide spectral range of 700–1400 nm. The Cr3+ ions enter the HfO6 octahedron and thus produce an NIR emission with a full width at half maximum of 190 nm and an internal quantum efficiency of 24% under 460 nm excitation. A prototype NIR‐pc‐LED surface light is demonstrated for machine vision by using NIR‐pc‐LEDs that combine the blue LED with SrHfO3:Cr. The work paves an avenue for designing super‐broadband NIR phosphors by doping Cr3+ or other ions into hosts with self‐trapped exciton emission (e.g., halide perovskites). [ABSTRACT FROM AUTHOR]

Green light is generally used as the transmitter of underwater wireless optical communication (UWOC) system, but the currently available light‐emitting diode (LED)‐based green light has a poor luminous flux density (i.e., low brightness) and a low wall‐plug efficiency (WPE), known as the "green gap". In this work, it is proposed to produce the laser‐driven green light by using blue laser diodes to pump the narrow‐band green‐emitting β‐Sialon phosphor‐in‐glass (PiG) film. The dominant wavelength of the laser‐driven green light can be tuned in the range of ≈520–540 nm, required for UWOC, by controlling the phosphor content at ≈60–80% and the film thickness at ≈150–185 µm. By introducing highly reflective TiO2 into the PiG film, the laser‐driven green light exhibits a maximum luminous flux density of 1260 lm mm−2 under blue laser excitation with a power density of 15.49 W mm−2. For UWOC application, the green light is demonstrated to have a modulation bandwidth of 1.76 MHz, a high WPE of 8.7%, and a long transmission distance of ≈61.6 m. This work suggests that the laser‐driven high‐brightness green light will be a promising light source for UWOC. [ABSTRACT FROM AUTHOR]

The bathymetry under the Amery Ice Shelf steers the flow of ocean currents transporting ocean heat, and thus is a prerequisite for precise modeling of ice‐ocean interactions. However, hampered by thick ice, direct observations of sub‐ice‐shelf bathymetry are rare, limiting our ability to quantify the evolution of this sector and its future contribution to global mean sea level rise. We estimated the bathymetry of this region from airborne gravity anomaly using simulated annealing. Unlike the current model which shows a comparatively flat seafloor beneath the calving front, our estimation results reveal a 255‐m‐deep shoal at the western side and a 1,050‐m‐deep trough at the eastern side, which are important topographic features controlling the ocean heat transport into the sub‐ice cavity. The new model also reveals previously unknown depressions and sills that are critical to an improved modeling of the sub‐ice‐shelf ocean circulation and induced basal melting. Plain Language Summary: The ocean currents are strongly steered by the seafloor topography. Therefore, the seafloor topography should be represented at fine resolution to study how the warm water melts the ice shelf from below. However, the seafloor beneath the largest ice shelf in East Antarctica remains poorly known, because the thick floating ice blocks direct bathymetric observations. We used gravity measured by airplane to infer the shape of the seafloor beneath the floating ice. The gravity‐inferred seafloor topography model is substantially improved over the existing BedMachine Antarctica model, and reveals previously unknown topographic features. The newly identified seafloor topographic features could improve our knowledge about how much ocean heat enters the sub‐ice cavity and how the ocean currents flow beneath the ice shelf. With this knowledge, scientists could more accurately project the response of the Amery Ice Shelf to ocean forcing and this region's future contribution to global mean sea level rise. Key Points: The seafloor topography beneath the Amery Ice Shelf, East Antarctica, is estimated from airborne gravity using simulated annealingEstimation results present updated ice front geometry, an important factor controlling the ocean heat transport into sub‐ice cavityThe model reveals previously unknown depressions at the western flank that are critical to an improved modeling of ocean circulation [ABSTRACT FROM AUTHOR]

Mascon products derived from Gravity Recovery and Climate Experiment satellite gravimetry data are widely used to study the Greenland ice sheet mass balance. However, the products released by different research groups—JPL, CSR, and GSFC—show noticeable discrepancies. To understand them, we compare those mascon products with mascon solutions computed in‐house using a varying regularization parameter. We show that the observed discrepancies are likely dominated by differences in the applied regularization. Furthermore, we present a numerical study aimed at an in‐depth analysis of regularization‐driven biases in the solutions. We demonstrate the ability of our simulations to reproduce 60%–80% of biases observed in real data, which proves that our simulations are sufficiently realistic. After that, we demonstrate that the quality of mascon‐based estimates can be increased by a proper modification of the applied regularization: no correlation between mascons is assumed when they belong to different drainage systems. Using both simulations and real data analysis, we show that the improved regularization mitigates signal leakage between drainage systems by 11%–56%. Finally, we validate various mascon solutions over the SW drainage system, using trends from (i) the GOCO‐06S model and (ii) the Input‐Output Method as control data. In general, the in‐house computed trend estimates are consistent with the trends from CSR and JPL solutions and the trends from the control data. Plain Language Summary: The mass variations of Greenland ice sheet (GrIS) have been widely monitored by the satellite mission named Gravity Recovery and Climate Experiment (GRACE). Currently, there are different research groups (i.e., JPL, CSR, and GSFC), which produce various mascon products from the GRACE data. Noticeable discrepancies, however, are shown in these mascon products. In this study, we try to analyze the reasons that cause the discrepancies, by varying with different strengths of regularization when estimating the mascon products using our variant of the mascon approach. Using both real data and simulation, we show that the observed discrepancies are likely dominated by differences in the applied regularization. Thereafter, we find that by utilizing a proper modification of the spatial constraint, the quality of the mascon estimates in GrIS can be obviously improved by 11%–56%. Finally, the trend estimates of the SW drainage systems from the GOCO‐06S model and the Input‐Output Method are utilized as independent data, to validate the mascon‐based solutions. It is found that the trends from CSR, JPL, and the estimates by the modified spatial constraints are in good agreement with the independent data. Key Points: State‐of‐the‐art GRACE mascon solutions show obvious discrepancies in Greenland mass anomalies over the period 2003–2014 (e.g., reaching the level of 100–200 Gt)The major cause of the large discrepancies is likely caused by different spatial constraintsWe recommend that no smoothing constraints are applied to neighboring mascons across drainage system boundaries [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) are promising materials for next‐generation lithium‐ion batteries while the lithium storage and cycling stability of TMOs are still limited. Herein, a novel Co3O4/MnO2/C composite using metal‐organic frameworks (MOFs) as sacrificial templates is reported. MnO2 and C shells are layer by layer coated on the MOF‐derived Co3O4/C samples via hydrothermal technique and heat treatment. When employed as anode materials for LIBs, the hierarchically heterostructured Co3O4/MnO2/C composites incorporate the merits of Co3O4, MnO2, and C, showing high Li storage performances at a current density of 0.2 A g−1 with an initial capacity of ∼1245.7 mAh g−1 and a reversible capacity of ∼854.9 mAh g−1 after 100 cycles, remarkable cycling stability, and excellent rate capability (almost 98 % recovery as the current density returns to the initial 0.2 A g−1, and especially, the specific capacity remains ∼587.6 mAh g−1 at a high current density of 2.0 A g−1). [ABSTRACT FROM AUTHOR]

To solve the problem associated with the huge volume change and low conductivity of Mn3O4, a novel C/Mn3O4 microsphere with Mn3O4 layer and void space sandwiched by nitrogen‐doped carbon (NC) is designed and fabricated. In this composite, the NC is obtained from the metal–organic frameworks (MOFs) and polydopamine (PDA). The preparation process is facile and effective without additional templates or redox solvents introduced. When used as anodes for lithium‐ion batteries (LIBs), the C/Mn3O4 composite incorporates the metrics of N‐doping, yolk‐shell structure, double carbon layer, mesoporous Mn3O4, showing an outstanding lithium storage of ≈1015.9 mAh g−1 at 0.2 A g−1 in the 250th cycle, high cycling stability (without clear capacity decay after 400 cycles), and excellent rate capability (capacity can fully recover as the current density returns back to the initial value of 0.2 A g−1). The yolk‐shell structure derived from MOFs can be expanded to fabricate other materials with improved performance. [ABSTRACT FROM AUTHOR]

Several postdepositional processes impact snow nitrate; however, only the isotopic effects of nitrate photolysis have been quantified. Here we discuss results from experiments in field Antarctic snow investigating isotopic fractionation of nitrate due to volatilization. At −35 °C, concentration and isotopic composition of nitrate remained constant during the 16‐day experiment. At −24 °C, 7.5% of nitrate was lost, synchronous with 1.5‰ decrease in δ18O and a constant δ15N. At −4 °C, 38% of nitrate was lost, and δ15N and δ18O decreased by 3.1 and 1.8‰, respectively. Results at −4 °C yield calculated fractionation constants close to theoretical estimates including equilibrium isotopic exchange between nitric acid and nitrate and the desorption of nitric acid from water in quasi‐liquid layers. This suggests that isotopic fractionation associated with nitrate volatilization across most of Antarctica, especially at sites with temperatures <−24 °C, should be minor, but the isotopic effects at warmer sites should be considered in interpreting archived nitrate records. Plain Language Summary: In polar regions, there is great interest in using nitrate archived in snow/ice to reconstruct aspects of atmospheric composition and the influence of natural versus man‐made emissions. However, nitrate can be lost from the snowpack, such that the archived signals do not directly reflect atmospheric loading. Stable isotopes of nitrate in snow/ice allow for tracking and understanding the origins of nitrate and how it might have changed after deposition. While the isotopic fractionation associated with photolytic loss of nitrate has been directly quantified, that of volatilization remains poorly understood. Thus, we completed field experiments in Antarctica to investigate the isotopic effects of nitrate volatilization from snow. Results show that nitrate volatilization loss is significant at −4 °C, resulting in an important change (depletion of heavy isotopes) in both nitrogen and oxygen in remaining snow nitrate. This can be largely explained by a combination of equilibrium isotopic exchange between nitric acid and nitrate and the desorption of nitric acid from water in ice surface layers. At lower temperatures (<−24 °C), nitrate loss is rather minor, and the isotopic fractionation is found to be negligible. The findings suggest that the isotopic effects of NO3− volatilization in snow are closely related to temperature. Key Points: Field experiments in Antarctica (over 16 days) were used to quantify the isotopic effects of NO3− volatilization from snowVolatilization at −4 °C depletes heavy isotopes of NO3− in remaining snow versus relatively constant isotopic ratios observed at −35 °CVolatilization can decrease δ15N in remaining snow NO3− in warm regions by several per mil, contrary to isotopic effects of photolysis [ABSTRACT FROM AUTHOR]

This paper describes the preparation of fumed silica compacts for thermal insulation, using wet processing method. A series of thermal insulation compacts based on fumed silica powder and glass fibers were prepared. The influence of the mass ratio about fumed silica and glass fibers on the fracture strength and thermal conductivity was investigated. The results showed that the fracture strength increased first and then decreased with the mass ratio increasing. The thermal conductivity decreased linearly with the mass ratio increasing. When the compact was pressed under 6 MPa with a mass ratio of 5:1, it exhibited excellent thermal insulation at room temperature with a thermal conductivity of 0.042W/ mK. Moreover, the compact was hydrophobic, after being modified by KH-570. [ABSTRACT FROM AUTHOR]