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"Liu, Le-Le"
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Enhancing homology-directed repair efficiency with HDR-boosting modular ssDNA donor
Despite the potential of small molecules and recombinant proteins to enhance the efficiency of homology-directed repair (HDR), single-stranded DNA (ssDNA) donors, as currently designed and chemically modified, remain suboptimal for precise gene editing. Here, we screen the biased ssDNA binding sequences of DNA repair-related proteins and engineer RAD51-preferred sequences into HDR-boosting modules for ssDNA donors. Donors with these modules exhibit an augmented affinity for RAD51, thereby enhancing HDR efficiency across various genomic loci and cell types when cooperated with Cas9, nCas9, and Cas12a. By combining with an inhibitor of non-homologous end joining (NHEJ) or the HDRobust strategy, these modular ssDNA donors achieve up to 90.03% (median 74.81%) HDR efficiency. The HDR-boosting modules targeting an endogenous protein enable a chemical modification-free strategy to improve the efficacy of ssDNA donors for precise gene editing.
Single-stranded DNA donors using current design parameters remain inefficient for precise gene editing. Here, the authors engineer RAD51-preferred sequences into HDR-boosting modules for donors, enhancing HDR efficiency across various genomic loci and cell types.
Journal Article
Effects of salt stress on interspecific competition between an invasive alien plant Oenothera biennis and three native species
Biological invasions and soil salinization have become increasingly severe environmental problems under global change due to sea-level rise and poor soil management. Invasive species can often outcompete native species, but few studies focus on whether invasive alien species are always superior competitors under increasing stressors. We grew an invasive grass species, Oenothera biennis L., and three native grass species ( Artemisia argyi Lévl. et Vant., Chenopodium album L., and Inula japonica Thunb.) as a monoculture (two seedlings of each species) or mixture (one seedling of O. biennis and one native species seedling) under three levels of salt treatments (0, 1, and 2 g/kg NaCl) in a greenhouse. We found that invasive O. biennis exhibited greater performance over native C. album and I. japonica , but lower performance compared to A. argyi , regardless of the soil salinity. However, salinity did not significantly affect the relative dominance of O. biennis . Interspecific competition enhanced the growth of O. biennis and inhibited the growth of I. japonica . Although O. biennis seedlings always had growth dominance over C. album seedlings, C. album was not affected by O. biennis at any salt level. At high salt levels, O. biennis inhibited the growth of A. argyi , while A. argyi did not affect the growth of O. biennis . Salt alleviated the competitive effect of O. biennis on I. japonica but did not mitigate the competition between O. biennis and the other two native species. Therefore, our study provides evidence for a better understanding of the invasive mechanisms of alien species under various salinity conditions.
Journal Article
Implementation of a 46-node quantum metropolitan area network
Quantum key distribution (QKD) enables secure key exchanges between two remote users. The ultimate goal of secure communication is to establish a global quantum network. The existing field tests suggest that quantum networks are feasible. To achieve a practical quantum network, we need to overcome several challenges including realizing versatile topologies for large scales, simple network maintenance, extendable configuration and robustness to node failures. To this end, we present a field operation of a quantum metropolitan-area network with 46 nodes and show that all these challenges can be overcome with cutting-edge quantum technologies. In particular, we realize different topological structures and continuously run the network for 31 months, by employing standard equipment for network maintenance with an extendable configuration. We realize QKD pairing and key management with a sophisticated key control centre. In this implementation, the final keys have been used for secure communication such as real-time voice telephone, text messaging and file transmission with one-time pad encryption, which can support 11 pairs of users to make audio calls simultaneously. Combined with intercity quantum backbone and ground–satellite links, our metropolitan implementation paves the way toward a global quantum network.
Journal Article
Distributed quantum phase estimation with entangled photons
Distributed quantum metrology can enhance the sensitivity for sensing spatially distributed parameters beyond the classical limits. Here we demonstrate distributed quantum phase estimation with discrete variables to achieve Heisenberg limit phase measurements. Based on parallel entanglement in modes and particles, we demonstrate distributed quantum sensing for both individual phase shifts and an averaged phase shift, with an error reduction up to 1.4 dB and 2.7 dB below the shot-noise limit. Furthermore, we demonstrate a combined strategy with parallel mode entanglement and multiple passes of the phase shifter in each mode. In particular, our experiment uses six entangled photons with each photon passing the phase shifter up to six times, and achieves a total number of photon passes N = 21 at an error reduction up to 4.7 dB below the shot-noise limit. Our research provides a faithful verification of the benefit of entanglement and coherence for distributed quantum sensing in general quantum networks.Distributed quantum metrology is demonstrated for both individual and averaged phase shifts by using discrete-variable entangled photons. An error reduction of 4.7 dB below the shot-noise limit is achieved when a total number of photon passes is 21.
Journal Article
Dual interfacial engineering of a Chevrel phase electrode material for stable hydrogen evolution at 2500 mA cm−2
Constructing stable electrodes which function over long timescales at large current density is essential for the industrial realization and implementation of water electrolysis. However, rapid gas bubble detachment at large current density usually results in peeling-off of electrocatalysts and performance degradation, especially for long term operations. Here we construct a mechanically-stable, all-metal, and highly active CuMo
6
S
8
/Cu electrode by in-situ reaction between MoS
2
and Cu. The Chevrel phase electrode exhibits strong binding at the electrocatalyst-support interface with weak adhesion at electrocatalyst-bubble interface, in addition to fast hydrogen evolution and charge transfer kinetics. These features facilitate the achievement of large current density of 2500 mA cm
−2
at a small overpotential of 334 mV which operate stably at 2500 mA cm
−2
for over 100 h. In-situ total internal reflection imaging at micrometer level and mechanical tests disclose the relationships of two interfacial forces and performance of electrocatalysts. This dual interfacial engineering strategy can be extended to construct stable and high-performance electrodes for other gas-involving reactions.
Stable electrodes which operate at large current density are essential for industrial water electrolysis. Here, a highly active Chevrel phase electrode is reported to achieve 2500 mA/cm
−2
current density for 300 hours at small overpotentials.
Journal Article
Satellite-to-ground quantum key distribution
Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD—a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.
Decoy-state quantum key distribution from a satellite to a ground station is achieved with much greater efficiency than is possible over the same distance using optical fibres.
Quantum security in orbit
The laws of quantum physics give rise to protocols for ultra-secure cryptography and quantum communications. However, to be useful in a global network, these protocols will have to function with satellites. Extending existing protocols to such long distances poses a tremendous experimental challenge. Researchers led by Jian-Wei Pan present a pair of papers in this issue that take steps toward a global quantum network, using the low-Earth-orbit satellite Micius. They demonstrate satellite-to-ground quantum key distribution, an integral part of quantum cryptosystems, at kilohertz rates over 1,200 kilometres, and report quantum teleportation of a single-photon qubit over 1,400 kilometres. Quantum teleportation is the transfer of the exact state of a quantum object from one place to another, without physical travelling of the object itself, and is a central process in many quantum communication protocols. These two experiments suggest that Micius could become the first component in a global quantum internet.
Journal Article
Satellite-based entanglement distribution over 1200 kilometers
Long-distance entanglement distribution is essential for both foundational tests of quantum physics and scalable quantum networks. Owing to channel loss, however, the previously achieved distance was limited to ~100 kilometers. Here we demonstrate satellite-based distribution of entangled photon pairs to two locations separated by 1203 kilometers on Earth, through two satellite-to-ground downlinks with a summed length varying from 1600 to 2400 kilometers. We observed a survival of two-photon entanglement and a violation of Bell inequality by 2.37 ± 0.09 under strict Einstein locality conditions. The obtained effective link efficiency is orders of magnitude higher than that of the direct bidirectional transmission of the two photons through telecommunication fibers.
Journal Article
Species mass transfer governs the selectivity of gas diffusion electrodes toward H2O2 electrosynthesis
The meticulous design of advanced electrocatalysts and their integration into gas diffusion electrode (GDE) architectures is emerging as a prominent research paradigm in the H
2
O
2
electrosynthesis community. However, it remains perplexing that electrocatalysts and assembled GDE frequently exhibit substantial discrepancies in H
2
O
2
selectivity during bulk electrolysis. Here, we elucidate the pivotal role of mass transfer behavior of key species (including reactants and products) beyond the intrinsic properties of the electrocatalyst in dictating electrode-scale H
2
O
2
selectivity. This tendency becomes more pronounced in high reaction rate (current density) regimes where transport limitations are intensified. By utilizing diffusion-related parameters (DRP) of GDEs (i.e., wettability and catalyst layer thickness) as probe factors, we employ both short- and long-term electrolysis in conjunction with in-situ electrochemical reflection-absorption imaging and theoretical calculations to thoroughly investigate the impact of DRP and DRP-controlled local microenvironments on O
2
and H
2
O
2
mass transfer. The mechanistic origins of diffusion-dependent conversion selectivity at the electrode scale are unveiled accordingly. The fundamental insights gained from this study underscore the necessity of architectural innovations for mainstream hydrophobic GDEs that can synchronously optimize mass transfer of reactants and products, paving the way for next-generation GDEs in gas-consuming electroreduction scenarios.
Electrocatalysts and assembled gas diffusion electrodes frequently exhibit discrepancies in selectivity during H
2
O
2
electrosynthesis. Here, the authors report the pivotal role of key species transport beyond the intrinsic properties of electrocatalysts in dictating electrode-scale H
2
O
2
selectivity.
Journal Article