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Super-Resolution (SR) Ultrasound imaging overcomes the wave diffraction limit and can reveal microvasculature by localizing spatially isolated contrast agents. Volumetric SR ultrasound imaging, however, is limited by both the fabrication and computational complexity associated with 2D matrix array probes. The most used diagnostic imaging modality, X-ray radiography, requires much simpler hardware than X-ray CT and can present volumetric information in a single projection image. Inspired by X-ray radiography, this study aims to investigate the feasibility of volumetric image projection super-resolution (VIP-SR) ultrasound using a 1D transducer array probe in simulation. Results show that, without a focusing lens, the capability of capturing volumetric information for a 1D array probe is significantly improved over that of a focused 1D array probe and is comparable to that of a 1.75D array probe with the same aperture size. Here we demonstrated the potential of VIP-SR as a high-resolution microvascular imaging technique with volumetric information and significantly reduced cost.

The microstructure evolution and creep property degradation of the Ni-based superalloy K417 were studied at different high-temperature thermal exposure conditions. The results showed that the equivalent radius of γ′ precipitates increased with the exposure time at all the temperatures and displayed spherical morphologies. Moreover, small blocky-type Cr-rich M23C6 carbides were observed due to the decomposition of the primary MC after exposure to 950 °C for 200 h and 50 h both at 1000 °C and 1050 °C. The creep-rupture lifetimes deteriorated with increased exposure time and temperature due to γ′ precipitates coarsening and the decomposition of the primary carbides. Furthermore, a physically based analytical model was developed to describe the influence of the microstructural evolution of the γ′ precipitates on the residual creep lifetime.

Prussian blue analogues (PBA) possess a high theoretical specific capacity for sodium ion batteries. However, cycling PBA to a high current density causes severe capacity fading. Here, we develop a selective edge-etching approach to tackle this long-standing issue of poor rate capability. Well-crystallized PBA particles were produced by hydrothermal treatment of a sodium hexacyanoferrate precursor dissolved in muriatic acid solution, which were then eroded in hydrochloric acid solution to promote selective etching along the edges of the PBA crystals. The defect concentration ([Fe(CN)6]4−) on the edge is denser than that at the face or corner, which stimulates the preferred etching of edges via the defect-induced heterogeneous mechanism. Due to the increasing exposed surface area and active sites, the etched PBA display much improved electrochemical performance with a capacity of 167 mA h g−1 at a current density of 5 mA g−1 and a capacity retention of 82.7% when the current density was increased to 40 mA g−1, demonstrating fast sodium ion transfer and high rate capability.

Current localization-based super-resolution ultrasound imaging requires a low concentration of flowing microbubbles to visualize microvasculature beyond the diffraction limit and acquisition is slow. Recent studies have shown that Acoustic Wave Sparsely Activated Localization Microscopy (AWSALM) using phase change nanodroplets can generate fast or even real-time super-resolution imaging. However, the optimal experimental conditions to activate the droplets for generating the super-resolution images are still unknown, especially the activation ultrasound amplitude or mechanical index (MI). The aim of this study is to investigate the effect of the activation MI on the repeated activation of decafluorobutane nanodroplets in vivo . Noninvasive ultrasound data acquisition on a rabbit kidney using the AWSALM pulse sequence was repeated for different activation MIs. It was found that the droplet activation was not observed in the rabbit kidney at an MI of 1.1. The activation of droplet started at an activation MI of 1.3. The contrast of activated droplet signals is maximized at an MI of 1.5 and decreased when the activation MI was increased above 1.5. Such understanding of the effects of activation MI could help improve droplet-base fast super-resolution imaging.

While control over chemical reactions is largely achieved by altering the intrinsic properties of catalysts, novel strategies are constantly being proposed to improve the catalytic performance in an extrinsic way. Since the fundamental chemical behavior of molecules can remarkably change when their molecular scale is comparable to the size of the space where they are located, creating spatially confined environments around the active sites offers new means of regulating the catalytic processes. We demonstrate through first-principles calculations that acetylene hydrogenation can exhibit significantly improved selectivity within the confined sub-nanospace between two-dimensional (2D) monolayers and the Pd(111) substrate. Upon intercalation of molecules, the lifting and undulation of a 2D monolayer on Pd(111) influence the adsorption energies of intermediates to varying extents, which, in turn, changes the energy profiles of the hydrogenation reactions. Within the confined sub-nanospace, the formation of ethane is always unfavorable, demonstrating effective suppression of the unwanted overhydrogenation. Moreover, the catalytic properties can be further tuned by altering the coverage of the adsorbates as well as strains within the 2D monolayer. Our results also indicate that for improving the selectivity, the strategy of spatial confinement could not be combined with that of single-atom catalysis, since the reactant molecules cannot enter the sub-nanospace due to the too weak adsorbate-substrate interaction. This work sheds new light on designing novel catalysts with extraordinary performance for the selective hydrogenation of acetylene.

Atomically monodispersed heterogeneous catalysts with uniform active sites and high atom utilization efficiency are ideal heterogeneous catalytic materials. Designing such type of catalysts, however, remains a formidable challenge. Herein, using a wet-chemical method, we successfully achieved a mesoporous graphitic carbon nitride (mpg-C3N4) supported dual-atom Pt2 catalyst, which exhibited excellent catalytic performance for the highly selective hydrogenation of nitrobenzene to aniline. The conversion of ˃99% is significantly superior to the corresponding values of mpg-C3N4-supported single Pt atoms and ultra-small Pt nanoparticles (~2 nm). First-principles calculations revealed that the excellent and unique catalytic performance of the Pt2 species originates from the facile H2 dissociation induced by the diatomic characteristics of Pt and the easy desorption of the aniline product. The produced Pt2/mpg-C3N4 samples are versatile and can be applied in catalyzing other important reactions, such as the selective hydrogenation of benzaldehyde and the epoxidation of styrene., Designing atomically monodispersed heterogeneous catalysts with uniform active sites and high atom utilization efficiency is of fundamental and practical interest. Here, the authors report a Pt2/mpg-C3N4 catalyst showing enhanced catalytic performance toward the selective hydrogenation and epoxidation

Contrast-enhanced photoacoustic imaging has shown great potential in medical imaging applications. Despite the obvious advantages of contrast enhancement, contrast agent signals attenuate significantly during the propagation process and can be masked by noise and clutter signals generated by tissue, resulting in the reduction of imaging sensitivity. In this study, we demonstrate that acoustic sub-aperture processing (ASAP) may be adapted to process photoacoustic images to generate high signal-to-noise ratio (SNR) images compared to the conventional spatiotemporal filtered images. Experiments were performed in vitro on a 0.6-mm diameter tube in a tissue-mimicking phantom containing a previously demonstrated exogenous photoacoustic contrast agent, Cyanine 7.5-coated nanodroplets. Data were acquired using a preclinical multispectral optoacoustic tomography (MOST) system. The results suggested that ASAP-assisted spatiotemporal filtering can improve SNR by about 8 dB in vitro compared to that without using ASAP. Besides flow imaging, this technique can also potentially benefit other photoacoustic imaging applications such as molecular imaging and super-resolution imaging.

Contrast-enhanced photoacoustic imaging has shown a great potential in various medical imaging applications. Although different types of customized contrast agents were developed over the decade, there is no commercial FDA-approved photoacoustic imaging contrast agents. This study shows the in vivo photoacoustic imaging of low-boiling-point phase-change nanodroplets, made using ingredients from an existing commercial microbubble ultrasound contrast agents without any dye coated, in a mouse to demonstrate that commercial ultrasound contrast agents may have the potential to be used to facilitate the clinical translation of photoacoustic imaging. Decafluorobutane-core lipid-shell nanodroplets were manufactured. The homemade decafluorobutane droplet solution has the same core composition as the commercial MicroMarker© (FUJIFILM, Visualsonics) and Sonazoid© (GE Healthcare) contrast microbubbles. The results show that, after activation, signals from the spleen region have been significantly enhanced. As the droplets do not have any dye coating on the surface, one potential reason for the photo-activation of the droplets could be that the blood cells nearby absorb energy from the light. As the ingredients of the droplets are the same as some existing commercial microbubble contrast agents, this study demonstrates that droplets made from condensed commercial bubbles may have the potential to be used to facilitate the clinical translation of contrast-enhanced photoacoustic imaging.

Ni3V2O8 is a promising anode material for Li‐ion batteries due to its high theoretical capacity that originates from the multivalence of nickel and vanadium. However, its low conductivity results in poor rate performance, and the large volume variation leads to poor stability induced by the inevitable pulverization and aggregation of active materials during cycling. To address these issues, a strategy by anchoring ultrafine Ni3V2O8 nanoparticles on reduced graphene oxide with hierarchical architecture (rGO@Ni3V2O8) is presented. This method is shown to effectively facilitate charge transfer, maintain structural integrity, and accommodate the volume variation during cycling. As a result, the rGO@Ni3V2O8 composite manifests a very stable and high reversible capacity of 1050 mA h g–1 over 200 cycles at a current density of 500 and 900 mA h g–1 after the subsequent 200 cycles at 1 A g–1. Furthermore, excellent rate capability is achieved. More than 45% of the capacity can be retained when the current density is increased from 0.1 to 10 A g–1.

In this paper, a turbine blade made of K417 nickel-based superalloy after service for 600 hours was investigated, the microstructural features were identified through metallographic observation, the size of γ' precipitates was adopted to quantitatively characterize the coarsening behavior, decomposition of primary carbides was also analyzed. In addition, micro-hardness tests were conducted on the turbine blade. The results indicated that size of γ' precipitates in the tip region of the blade had a small increase, the decomposition of primary carbides did not occur. Meanwhile, the little reduction in micro-hardness in the tip section was found, which was caused by the coarsening of γ' precipitates. To sum up, the service induced damage of the turbine blade after service for 600 hours was slight, the degeneration in the tip region was relatively obvious due to high temperature, the result is of great significance to evaluating the service safety of service exposed turbine blades.