Enzymatic reductions catalyzed by reductases generally depend on reduced nicotinamide cofactors as a hydride source. However, for industrial viability, it is more cost-effective to use water as the hydrogen source, bypassing the requirement for the cofactor. Here we report a hybrid photo-biocatalyst system based on infrared (IR) light and responsive reductive graphene quantum dots (rGQDs), for performing the direct transfer of hydrogen from water to prochiral substrates. The photo-biocatalyst, assembled from rGQDs and cross-linked aldo-keto reductase (AKR), mediates the synthesis of the pharmaceutical intermediate, (R)−1-[3,5-bis(trifluoromethyl)-phenyl] ethanol ((R)−3,5-BTPE), in 82% yield and >99.99% ee under IR illumination. Our photo-enzymatic systems can also be effectively used to drive the enzymatic reduction of imines and alkenes. Since the hybrid photo-biocatalysts are insoluble, they can be readily recovered and recycled. This work opens new avenues to create artificial photo-biocatalyst systems, enabling the facile coupling of renewable solar energy and sustainable chemical production.

Nuclear energy emerges as a promising and environmentally friendly solution to counter the escalating levels of greenhouse gases resulting from excessive fossil fuel usage. Essential to harnessing this energy are nuclear batteries, devices designed to generate electric power by capturing the energy emitted during nuclear decay, including α or β particles and γ radiation. The allure of nuclear batteries lies in their potential for extended lifespan, high energy density, and adaptability in harsh environments where refueling or battery replacement may not be feasible. In this review, we narrow our focus to nuclear batteries utilizing non-thermal converters such as α- or β-voltaics, as well as those employing scintillation intermediates. Recent advancements in state-of-the-art direct radiation detectors and scintillators based on metal perovskite halides (MPHs) and chalcogenides (MCs) are compared to traditional detectors based on silicon and III-V materials, and scintillators based on inorganic lanthanide crystals. Notable achievements in MPH and MC detectors and scintillators, such as nano-Gy sensitivity, 100 photons/keV light yield, and radiation hardness, are highlighted. Additionally, limitations including energy conversion efficiency, power density, and shelf-life due to radiation damage in detectors and scintillators are discussed. Leveraging novel MPH and MC materials has the potential to propel nuclear batteries from their current size and power limitations to miniaturization, heightened efficiency, and increased power density. Furthermore, exploring niche applications for nuclear batteries beyond wireless sensors, low-power electronics, oil well monitoring, and medical fields presents enticing opportunities for future research and development.

Climate change with extreme hydrological conditions, such as drought and flood, bring new challenges to seepage behavior and the stability of earthfill dams. Taking a drought-stricken earthfill dam of China as an example, the influence of drought-flood cycles on dam seepage behavior is analyzed. This paper includes a clay sample laboratory experiment and an unsteady finite element method seepage simulation of the mentioned dam. Results show that severe drought causes cracks on the surface of the clay soil sample. Long-term drought causes deeper cracks and induces a sharp increase of suction pressure, indicating that the cracks would become channels for rain infiltration into the dam during subsequent rainfall, increasing the potential for internal erosion and decreasing dam stability. Measures to prevent infiltration on the dam slope surface are investigated, for the prevention of deep crack formation during long lasting droughts. Unsteady seepage indicators including instantaneous phreatic lines, equipotential lines and pore pressure gradient in the dam, are calculated and analyzed under two assumed conditions with different reservoir water level fluctuations. Results show that when the water level changes rapidly, the phreatic line is curved and constantly changing. As water level rises, equipotential lines shift upstream, and the pore pressure gradient in the dam’s main body is larger than that of steady seepage. Furthermore, the faster the water level rises, the larger the pore pressure gradient is. This may cause internal erosion. Furthermore, the case of a cracked upstream slope is modelled via an equivalent permeability coefficient, which shows that the pore pressure gradient in the zone beneath the cracks increases by 5.9% at the maximum water level; this could exacerbate internal erosion. In addition, results are in agreement with prior literature that rapid drawdown of the reservoir water level is detrimental to the stability of the upstream slope based on embankment slope stability as calculated by the Simplified Bishop Method. It is concluded that fluctuations of reservoir water level should be strictly controlled during drought-flood cycles; both the drawdown rate and the fill rate must be regulated to avoid the internal erosion of earthfill dams.