Air-Promoted Light-Driven Hydrogen Production from Bioethanol over Core/Shell Cr2O3@GaN Nanoarchitecture

Light-driven hydrogen production from biomass derivatives offers a path towards carbon neutrality. It is often however operated with the limitations of sluggish kinetics and severe coking. Herein, a disruptive air-promoted strategy is explored for efficient and durable light-driven hydrogen production from ethanol over a core/shell Cr2O3@GaN nanoarchitecture. The correlative computational and experimental investigations show ethanol is energetically favorable to be adsorbed on the Cr2O3@GaN interface, followed by dehydrogenation toward acetaldehyde and protons by photoexcited holes. The released protons are then consumed for H2 evolution by photogenerated electrons. Afterward, O2 can be evolved into active oxygen species and promote the deprotonation and C-C cleavage of the key C2 intermediate, thus significantly lowering the reaction energy barrier of hydrogen evolution and removing the carbon residual with inhibited overoxidation. Consequently, hydrogen is produced at a high rate of 76.9 mole H2 per gram Cr2O3@GaN per hour by only feeding ethanol, air, and light, leading to the achievement of a turnover number of 266,943,000 mole H2 per mole Cr2O3 over a long-term operation of 180 hours. Notably, an unprecedented light-to-hydrogen efficiency of 17.6 % is achieved under concentrated light illumination. The simultaneous generation of aldehyde from ethanol dehydrogenation enables the process more economically promising.

Acoustic Cell Patterning for Structured Cell-Laden Hydrogel Fibers/Tubules

Cell-laden hydrogel fibers/tubules are one of the fundamentals of tissue engineering. They have been proven as a promising method for constructing biomimetic tissues, such as muscle fibers, nerve conduits, tendon and vessels, etc. However, current hydrogel fiber/tubule production methods have limitations in ordered cell arrangements, thus impeding the biomimetic configurations. Acoustic cell patterning is a cell manipulation method that has good biocompatibility, wide tunability, and is contact-free. However, there are few studies on acoustic cell patterning for fiber production, especially on the radial figure cell arrangements, which mimic many native tissue-like cell arrangements. Here, an acoustic cell patterning system that can be used to produce hydrogel fibers/tubules with tunable cell patterns is shown. Cells can be pre-patterned in the liquid hydrogel before being extruded as cross-linked hydrogel fibers/tubules. The radial patterns can be tuned with different complexities based on the acoustic resonances. Cell viability assays after 72 h confirm good cell viability and proliferation. Considering the biocompatibility and reliability, the present method can be further used for a variety of biomimetic fabrications.

Topographic metabolism-function relationships in Alzheimer's disease: A simultaneous PET/MRI study

Disruptions of neural metabolism and function occur in parallel during Alzheimer's disease (AD). While many studies have shown diverse metabolic-functional relationships in specific brain regions, much less is known about how large-scale network-level functional activity is associated with the topology of metabolism in AD. In this study, we took the advantages of simultaneous PET/MRI and multivariate analyses to investigate the associations between AD-related stereotypical spatial patterns (topographies) of glucose metabolism, measured by fluorodeoxyglucose PET, and functional connectivity, measured by resting-state functional MRI. A total of 101 participants, including 37 patients with AD, 25 patients with mild cognitive impairment (MCI), and 39 cognitively normal controls, underwent PET/MRI scans and cognitive assessments. Three pairs of distinct but optimally correlated metabolic and functional topographies were identified, encompassing large-scale networks including the default-mode, executive and control, salience, attention, and subcortical networks. Importantly, the metabolic-functional associations were not only limited to one-to-one-corresponding regions, but also occur in remote and non-overlapping regions. Furthermore, both glucose metabolism and functional connectivity, as well as their linkages, exhibited various degrees of disruptions in patients with MCI and AD, and were correlated with cognitive decline. In conclusion, our results support distributed and heterogeneous topographic associations between metabolism and function, which are jeopardized by AD. Findings of this study may deepen our understanding of the pathological mechanism of AD through the perspectives of both local energy efficiency and long-term interactions between synaptic disruption and functional disconnection contributing to the clinical symptomatology in AD.

Photoredox Nickel-Catalysed Stille Cross-Coupling Reactions

The Stille cross-coupling reaction is one of the most common strategies for the construction of C-C bonds. Despite notable strides in the advancement of the Stille reaction, persistent challenges persist in hindering its greener evolution. These challenges encompass multiple facets, such as the high cost of precious metals and ligands, the demand for various additives, and the slow reaction rate. In comparison to the dominant palladium-catalysed Stille reactions, cost-effective nickel-catalysed systems lag behind, and enantioconvergent Stille reactions of racemic stannanes remain undeveloped. Herein, we present a pioneering instance of nickel-catalysed enantioconvergent Stille cross-coupling reactions of racemic stannane reagents, resulting in the formation of C-C bonds in good to high yields with excellent stereoselectivity. This strategy provides a practical, scalable, and operationally straightforward method for the synthesis of C(sp3 )-C(sp3 ), C(sp3 )-C(sp2 ), and C(sp3 )-C(sp) bonds under exceptionally mild conditions (without additives and bases, ambient temperature). The innovative use of synergistic photoredox/nickel catalysis enables a novel single-electron transmetalation process of stannane reagents, providing a new research paradigm of Stille reactions.