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Purpose: Adopting adaptive behavior has become a basic measure for farmers because the increasingly severe climate change is affecting agricultural production. Perception is a critical first step in adopting adaptive behaviors. Livelihood resilience represents a farmer's ability to adapt to climate change. Therefore, this article aims to explore the impact of livelihood resilience and climate change perception on the climate change adaptation behavior of farmers in the Qinling Mountains region of China. Design/methodology/approach: In this study, 443 micro-survey data of farmers are obtained through one-on-one interviews with farmers. The Logit model and Poisson regression model are used to empirically examine the impact of farmers' livelihood resilience and climate change perception on their climate change adaptation behaviors. Findings: It was found that 86.68% of farmers adopt adaptive behaviors to reduce the risks of facing climate change. Farmers' perception of extreme weather has a significant positive impact on their adaptive behavior under climate change. The resilience of farmers' livelihoods and their perception of rainfall have a significant positive impact on the intensity of their adaptive behavior under climate change. Climate change adaptation behaviors are also different for farmers with different levels of livelihood resilience. Originality/value: Based on the results, policy recommendations are proposed to improve farmers' perception of climate change, enhance the sustainability of farmers' adaptive behavior to climate change, strengthen emergency management and infrastructure construction and adjust and upgrade farmers' livelihood models.

The gut microbiota are known to play an important role in host health and disease. Alterations in the gut microbiota composition can disrupt the stability of the gut ecosystem, which may result in noncommunicable chronic diseases (NCCDs). Remodeling the gut microbiota through personalized nutrition is a novel therapeutic avenue for both disease control and prevention. However, whether there are commonly used gut microbiota-targeted diets and how gut microbiota–diet interactions combat NCCDs and improve health remain questions to be addressed. Lactoferrin (LF), which is broadly used in dietary supplements, acts not only as an antimicrobial in the defense against enteropathogenic bacteria but also as a prebiotic to propagate certain probiotics. Thus, LF-induced gut microbiota alterations can be harnessed to induce changes in host physiology, and the underpinnings of their relationships and mechanisms are beginning to unravel in studies involving humans and animal models.

ABSTRACTA Tunable Friction Pendulum System (TFPS) was proposed to investigate its seismic isolation control performance in bridge structures. First, the structural design and theoretical model of TFPS are given. Second, the mechanical properties of TFPS are studied through finite element simulation. Then, the above TFPS is introduced into the bridge structure, and the analysis model is established based on SAP2000. Finally, a nonlinear time-history analysis is carried out on the bridge structure, and the seismic isolation performance of TFPS is evaluated by using the dynamic characteristic response index of the bridge structure. Theoretical derivation and finite element analysis results show that TFPS can adjust the dynamic characteristics in real time according to the spectral characteristics of the ground motion input and the response of the structure itself, so that the friction force can be continuously adjusted and energy consumption can be adjusted.

When multiple devices seek to offload computational tasks to their access point, the nature of the multiple access scheme plays a critical role in the system performance. For a system with heterogeneous tasks, we adopt a time-slotted signaling architecture in which different numbers of devices transmit in each slot, subject to individual power constraints. We consider the problem of jointly selecting the devices that will offload, along with optimizing their communication resources (their powers and rates in each time slot, and the time slot lengths) so as to minimize the a weighted sum of the energy expended by the devices. We employ a customized tree search algorithm for the offloading decisions in which a resource allocation problem is solved at each node. For time-division multiple access (TDMA) and “rate optimal” multiple access, we obtain reduced-dimension convex formulations of the resource allocation problem. For non-orthogonal multiple access (NOMA) with independent decoding (ID) or fixed-order sequential decoding (FOSD) we show that the resource allocation problem has a difference-of-convex structure and we develop a successive convex approximation algorithm with feasible point pursuit. Furthermore, for the FOSD scheme we obtain a closed-form expression that provides the optimal decoding order when it is feasible, and efficient algorithms for finding a good decoding order when it is not. Our results capture the inherent tradeoffs between the complexity of a multiple access scheme (and its resource allocation algorithm), and its performance in the computation offloading application.

SiGe/Si multilayer is the core structure of the active area of gate-all-around field-effect transistors and semiconductor quantum computing devices. In this paper, high-quality SiGe/Si multilayers have been grown by a reduced-pressure chemical vapor deposition system. The effects of temperature, pressure, interface processing (dichlorosilane (SiH2Cl2, DCS) and hydrogen chloride (HCl)) on improving the transition thickness of SiGe to Si interfaces were investigated. The interface quality was characterized by transmission electron microscopy/atomic force microscopy/high-resolution X-ray diffraction methods. It was observed that limiting the migration of Ge atoms in the interface was critical for optimizing a sharp interface, and the addition of DCS was found to decrease the interface transition thickness. The change of the interfacial transition layer is not significant in the short treatment time of HCl. When the processing time of HCl is increased, the internal interface is optimized to a certain extent but the corresponding film thickness is also reduced. This study provides technical support for the acquisition of an abrupt interface and will have a very favorable influence on the performance improvement of miniaturized devices in the future.

The flavoenzyme nicotine oxidoreductase (NicA2) is a promising injectable treatment to aid in the cessation of smoking, a behavior responsible for one in ten deaths worldwide. NicA2 acts by degrading nicotine in the bloodstream before it reaches the brain. Clinical use of NicA2 is limited by its poor catalytic activity in the absence of its natural electron acceptor CycN. Without CycN, NicA2 is instead oxidized slowly by dioxygen (O2), necessitating unfeasibly large doses in a therapeutic setting. Here, we report a genetic selection strategy that directly links CycN-independent activity of NicA2 to growth of Pseudomonas putidaS16. This selection enabled us to evolve NicA2 variants with substantial improvement in their rate of oxidation by O2. The encoded mutations cluster around a putative O2tunnel, increasing flexibility and accessibility to O2in this region. These mutations further confer desirable clinical properties. A variant form of NicA2 is tenfold more effective than the wild type at degrading nicotine in the bloodstream of rats.

Interacting electrons in flat bands give rise to a variety of quantum phases. One fundamental aspect of such states is the ordering of the various flavours—such as spin or valley—that the electrons can possess and the excitation spectrum of the broken-symmetry states that they form. These properties cannot be probed directly with electrical transport measurements. The zeroth Landau level of monolayer graphene with fourfold spin–valley degeneracy is a model system for such investigations, but the nature of its broken-symmetry states—particularly at partial fillings—is still not understood. Here we demonstrate a non-invasive spectroscopic technique with a scanning tunnelling microscope and use it to perform measurements of the valley polarization of the electronic wavefunctions and their excitation spectrum in the partially filled zeroth Landau level of graphene. We can extract information such as the strength of the Haldane pseudopotentials that characterize the repulsive interactions underlying the fractional quantum states. Our experiments also demonstrate that fractional quantum Hall phases are built upon broken-symmetry states that persist at partial filling. Our experimental approach quantifies the valley phase diagram of the partially filled Landau level as a model flat-band platform, which is applicable to other graphene-based electronic systems.

The development of the medicinal trade and markets in late imperial China increased anxiety among scholarly physicians about the authenticity of medicines. Even though the market was typically depicted by scholarly physicians as a place full of tricks and deceptions, it was a repertoire where practical knowledge about authentication was created and circulated. The specialized knowledge was mainly transmitted through oral tradition. But in some instances, it was also written down by scholarly physicians or merchants, allowing us to reconstruct the techniques and their underlying rationales. Authentication of medicines mobilized multiple sensory perceptions of the human body, consisting of observing, tasting, smelling, touching, and performing small tests. All these techniques played different roles in the practice of authentication. Even though these sensory techniques seemed like a collection of trivial and practical records without any coherent rationales, an underlying episteme could be detected through a close investigation. Merchants and practitioners in the market did not understand the nature and materiality of medicines by any established theories. Instead, they actively engaged with the tangible form of medicines through the senses and bodily techniques. This sensory form of knowing indicates a type of practical expertise that is distant from the scholarly tradition of materia medica in late imperial China.

Rapid identification and quantitative simultaneous analysis for multiple pesticide in real samples based on surface-enhanced Raman spectroscopy (SERS) is still a challenge because of sample complexity, reproducibility, and stability of SERS substrate. With use of colloidal silver nanoparticles loaded three-dimensional (3D) silica photonic microspheres (SPMs) array as the analytical platform, a SERS-based array assay for multiple pesticides was developed in this work. The silver nanoparticles were fixed into the gaps formed by the self-assembled nanospheres of the 3D SPMs to produce “hot spots”, on which the Raman enhanced effect was up to 9.86 × 107and the maximum electric field enhancement effect reached to 9.75 times, ensuring the target pesticides on the surface of the SERS-substrate integrated SPM can be detected sensitively. Using 2,4-dichlorophenoxyacetic acid (2,4-D), glyphosate, and imidacloprid as the testing pesticides, the label-free and high-throughput SERS assay for simultaneous detection of the pesticides was established, giving good linear detection ranges (0.1–204.8 μg/mL for 2,4-D, 0.3–247.9 μg/mL for glyphosate, and 0.2–204.8 μg/mL for imidacloprid) and low detection limits (3.03 ng/mL for 2,4-D, 3.14 ng/mL for glyphosate, and 8.82 ng/mL for imidacloprid). The spiked recovery rates in the real samples were measured in the range of 82–112%, which was consistent with that of the classical standard methods. The label-free 3D SERS array analytical platform provides a powerful tool for high-throughput and low-cost screening of multiple pesticide residues in real samples.

ObjectivePancreatic ductal adenocarcinoma (PDAC) is among the most immunosuppressive tumour types. The tumour immune microenvironment (TIME) is largely driven by interactions between immune cells and heterogeneous tumour cells. Here, we aimed to investigate the mechanism of tumour cells in TIME formation and provide potential combination treatment strategies for PDAC patients based on genotypic heterogeneity.DesignHighly multiplexed imaging mass cytometry, RNA sequencing, mass cytometry by time of flight and multiplex immunofluorescence staining were performed to identify the pro-oncogenic proteins associated with low immune activation in PDAC. An in vitro coculture system, an orthotopic PDAC allograft tumour model, flow cytometry and immunohistochemistry were used to explore the biological functions of cysteine-rich intestinal protein 1 (CRIP1) in tumour progression and TIME formation. RNA sequencing, mass spectrometry and chromatin immunoprecipitation were subsequently conducted to investigate the underlying mechanisms of CRIP1.ResultsOur results showed that CRIP1 was frequently upregulated in PDAC tissues with low immune activation. Elevated CRIP1 expression induced high levels of myeloid-derived suppressor cell (MDSC) infiltration and fostered an immunosuppressive tumour microenvironment. Mechanistically, we primarily showed that CRIP1 bound to nuclear factor kappa-B (NF-κB)/p65 and facilitated its nuclear translocation in an importin-dependent manner, leading to the transcriptional activation of CXCL1/5. PDAC-derived CXCL1/5 facilitated the chemotactic migration of MDSCs to drive immunosuppression. SX-682, an inhibitor of CXCR1/2, blocked tumour MDSC recruitment and enhanced T-cell activation. The combination of anti-PD-L1 therapy with SX-682 elicited increased CD8+T cell infiltration and potent antitumor activity in tumour-bearing mice with high CRIP1 expression.ConclusionsThe CRIP1/NF-κB/CXCL axis is critical for triggering immune evasion and TIME formation in PDAC. Blockade of this signalling pathway prevents MDSC trafficking and thereby sensitises PDAC to immunotherapy.

In this article, we reported a critical improvement on the measurement method for the dielectric dispersion characteristics of hydrate-bearing sediment in a frequency range between 1 MHz and 3 GHz, and, with the use of the method, a systematic evaluation of the microwave dielectric dispersion of the hydrate-bearing artificial sediment and influence factors. First, the optimized and verified procedure of the dielectric detection method was introduced, followed with the results of complex permittivity (CP) measurements obtained by carrying out a series of experiments with different dielectric configurations. To balance the frequency coverage of the dispersion characteristic of both hydrate and solution among the dielectric measurement, the inversion means of the open-ended coaxial (OEC) probe was improved so that the lower frequency limit of the method has been extended as low as 1.0 MHz. Furthermore, error analysis based on the experimental results among the overlapping frequency range with cylindrical capacitance verified the detecting accuracy of the OEC probes below 10 MHz. The microwave dielectric dispersion of hydrate-bearing artificial sediment as a function of sediment particle size, temperature, and clay content was determined. It was found that the dielectric spectrum is not only routinely dependent on the porosity and temperature, but more importantly, the introduction of clay content has a distinct dynamic influence on the dielectric spectrum and the formation and dissociation process.

This review investigates the utilization of the One Health approach to advance sustainable development and enhance health in the Hainan tropical rainforest, which is a unique ecosystem with significant biodiversity and environmental value. The region is confronted with threats arising from human activities and climate change, impacting both the health of the inhabitants and the ecosystem. The Hainan tropical rainforests create an ideal habitat for the transmission of mosquito-borne diseases, such as dengue fever and malaria, between humans and animals. The hot and humid climate creates favorable conditions for mosquito proliferation, while increased human encroachment into forested areas escalates the risk of contact with wildlife reservoirs of these diseases. Proactive surveillance of emerging infectious diseases in the forests and animal populations of Hainan is crucial for early detection and swift response to potential public health hazards. By embracing the interdisciplinary and collaborative principles of the One Health approach, this review aims to safeguard the ecosystem while fostering development. The introduction offers insights into the significance of the One Health concept, its relevance to environmental conservation, human health, and animal health. Subsequently, the paper delves into the practical application of the One Health approach in the Hainan tropical rainforest, using it as a case study. This application entails raising awareness of ecosystem health through educational initiatives and public outreach, implementing effective ecological conservation measures, promoting wildlife conservation efforts, and monitoring and preventing potential disease outbreaks. Furthermore, the paper highlights the importance of the One Health approach in achieving sustainable development in the Hainan tropical rainforest. It also explores potential research directions and associated challenges. By prioritizing the collective well-being of humans, animals, and the environment, the One Health approach offers a means to balance ecosystem conservation and human welfare.

Spinel oxides, with the formula AB2O4(A and B represent metal ions) perform superior electrocatalytic characteristic when A and B are transition metals like Co, Fe, Mn, etc. Abundant researches have been attached to the structure designments while methods are often energy-intensive and inefficient. Here, we devised a universal strategy to achieve rapid synthesis of nanocrystalline spinel materials with multiple components (Co3O4, Mn3O4, CoMn2O4and CoFe2O4are as examples), where phase formation is within 15 s. Under the Joule-heating shock, a crack-break process of microcosmic phase transformation is observed by in-situtransmission electron microscopy. The half-wave potential values of Co3O4JH, Mn3O4JH, CoMn2O4JH and CoFe2O4JH in the electrocatalytic oxygen reduction reaction were 0.77, 0.78, 0.79 and 0.76, respectively. This suggests that the Joule heating is a fast and efficient method for the preparation of spinel oxide electrocatalysts.

• Micro-area potential difference (MAPD) existed on Ti-M alloy due to the second phase formation. • MAPD played a key factor in the antibacterial properties of titanium alloys. • MAPD enhances the galvanic reaction and electron transfer of Ti-M alloy. • Electron transfer induces ROS in bacteria but does not affect MC3T3 proliferation and adhesion. Antimicrobial material is highly desired because of the increasing demand in biomedical application to prevent from the formation of biofilm. A common strategy for enhancing the antibacterial property of a metal material is to incorporate toxic metal such as Cu and Ag. However, the reported Cu2+ or Ag+ released concentration from antibacterial alloys was much less than the reported minimum inhibitory ion concentrations (MIC), revealing the existence of an unknown alternative antimicrobial mechanism not relying on the toxicity of the metal ions. Herein, we proposed a new antibacterial mechanism that the antibacterial effectiveness of the different alloys is proportional to the micro-area potential differences (MAPDs) on the surface of the alloys. We designed three kinds of Ti-M (M=Zr, Ta and Au) alloys to eliminate the potential antibacterial contribution from Cu and Ag ion. We demonstrated that high MAPDs are associated with great production of reactive oxygen species (ROS), resulting in the killing effect to the biofilm known to be associated with implant infections (Staphlococcus aureus and Escherichia coli). These results provide new insights for the design of antibacterial alloys. [ABSTRACT FROM AUTHOR]

Common oat (Avena sativa) is an important cereal crop serving as a valuable source of forage and human food. Although reference genomes of many important crops have been generated, such work in oat has lagged behind, primarily owing to its large, repeat-rich polyploid genome. Here, using Oxford Nanopore ultralong sequencing and Hi-C technologies, we have generated a reference-quality genome assembly of hulless common oat, comprising 21 pseudomolecules with a total length of 10.76 Gb and contig N50 of 75.27 Mb. We also produced genome assemblies for diploid and tetraploid Avenaancestors, which enabled the identification of oat subgenomes and provided insights into oat chromosomal evolution. The origin of hexaploid oat is inferred from whole-genome sequencing, chloroplast genomes and transcriptome assemblies of different Avenaspecies. These findings and the high-quality reference genomes presented here will facilitate the full use of crop genetic resources to accelerate oat improvement.

RNA N6-methyladenosine (m6A) is an emerging regulator of mRNA modifications and represents a novel player in tumorigenesis. Although it has functional significance in both pathological and physiological processes, the role of m6A modification in pancreatic ductal cancer (PDAC) remains elusive. Here, we showed that high fat mass and obesity-associated gene (FTO) expression was associated with a poor prognosis in PDAC patients and that suppression of FTO expression inhibited cell proliferation. Here, m6A sequencing (m6A-seq) was performed to screen genes targeted by FTO. The effects of FTO stimulation on the biological characteristics of pancreatic cancer cells, including proliferation and colony formation, were investigated in vitro and in vivo. The results indicate that FTO directly targets platelet-derived growth factor C (PDGFC) and stabilizes its mRNA expression in an m6A-YTHDF2-dependent manner. m6A-methylated RNA immunoprecipitation-qPCR (MeRIP-qPCR), RNA immunoprecipitation (RIP), and luciferase reporter assays were employed to validate the specific binding of FTO to PDGFC. PDGFC upregulation led to reactivation of the Akt signaling pathway, promoting cell growth. Overall, our study reveals that FTO downregulation leads to increased m6A modifications in the 3ʹ UTR of PDGFC and then modulates the degradation of its transcriptional level in an m6A-YTHDF2-dependent manner, highlighting a potential therapeutic target for PDAC treatment and prognostic prediction.

Learning from nature photosynthesis, the development of efficient artificial catalysts for water oxidation is an ongoing challenge. Herein, a lamellar cobalt oxide (CoO), black phosphorus (BP) and reduced graphene oxide (RGO) hybrid electrocatalyst is reported. BP domains are anchored on RGO and coated with CoO viaP–O bonds. The widespread P–O bond network constitutes the proton acceptor and forms a proton exit channel, akin to the use of Asp61 in Photosystem II (PSII). The innermost kernel layer RGO serves as the current collector and forms an electron exit channel, mimicking the function of Tyr161 for charge transfer. The outermost encapsulation CoO layer acts as water oxidation catalyst (WOC). These biology-inspired features endow an outstanding OER performance of the hybrid material with a low overpotential of 206 mV at a current density of 10 mA cm−2. This work provides a new design guide for OER electrocatalysts through constructing two specialized channels for proton and electron transfer.

Organic–inorganic hybrid nonlinear optical (NLO) crystals have been attracting increasing attention because of their unique ability to combine the structural diversity of the organic moiety and the high stability of the inorganic moiety. However, organic NLO genes are rare. Herein, a new organic NLO material gene, the 2-aminopyrimidinium cation (C4H6N3)+((2AP)+), is reported, which constructs a novel organic–inorganic hybrid (C4H6N3)+(H2PO3)−(2APP) that exhibits excellent NLO properties and thermal stability, e.g., strong second-harmonic generation (SHG) intensity (2 × KDP), large birefringence (0.225 at 589.3 nm), high laser-induced-damage threshold (1.7 × KDP), and one of the highest thermal stabilities among the metal-free-(2AP)+-containing compounds. Our first-principles theoretical studies confirm the dominant contribution of (2AP)+to optical properties. The inorganic phosphite anions well separate the (2AP)+cations to successfully eliminate the unwanted centrosymmetric trap that is induced by the dipole–dipole interactions between (2AP)+cations. Furthermore, the unique layered structure decorated by the uniformly oriented individual (2AP)+chromophores, dramatically enhances the quantum yield of purple fluorescence (Φ = 30.6%), which is 3 orders of magnitude higher than that of pure 2AP and its derivatives.

Accurately designing and synthesizing new deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystals that are limited by the so-called “200 nm wall” on their transparency windows remain challenging. On the basis of a bandgap-directed computer-aided material design approach, two new NLO sulfates, KMgSO4F and KZnSO4F, are designed and successfully synthesized. They feature three-dimensional frameworks closely related to the commercial NLO crystal, KTiOPO4(KTP). Remarkably, the transmittance spectrum based on a single crystal indicates that the transparency window of KZnSO4F is significantly blue-shifted to <190 nm from 350 nm for KTP. The microscopic origin of this significant transparent window blue shift is illustrated well by first-principles calculations. This work pushes the transparency windows of KTP-like NLO sulfates into the deep-UV spectral region for the first time and will pave a prospective way to the accurate design and synthesis of new deep-UV NLO materials.

The emergence of superconductivity and correlated insulators in magic-angle twisted bilayer graphene (MATBG) has raised the intriguing possibility that its pairing mechanism is distinct from that of conventional superconductors1–4, as described by the Bardeen–Cooper–Schrieffer (BCS) theory. However, recent studies have shown that superconductivity persists even when Coulomb interactions are partially screened5,6. This suggests that pairing in MATBG might be conventional in nature and a consequence of the large density of states of its flat bands. Here we combine tunnelling and Andreev reflection spectroscopy with a scanning tunnelling microscope to observe several key experimental signatures of unconventional superconductivity in MATBG. We show that the tunnelling spectra below the transition temperature Tcare inconsistent with those of a conventional s-wave superconductor, but rather resemble those of a nodal superconductor with an anisotropic pairing mechanism. We observe a large discrepancy between the tunnelling gap ΔT, which far exceeds the mean-field BCS ratio (with 2ΔT/kBTc~ 25), and the gap ΔARextracted from Andreev reflection spectroscopy (2ΔAR/kBTc~ 6). The tunnelling gap persists even when superconductivity is suppressed, indicating its emergence from a pseudogap phase. Moreover, the pseudogap and superconductivity are both absent when MATBG is aligned with hexagonal boron nitride. These findings and other observations reported here provide a preponderance of evidence for a non-BCS mechanism for superconductivity in MATBG.

Intense interests in mid-infrared (MIR) nonlinear optical (NLO) crystals have erupted in recent years due to the development of optoelectronic applications ranging from remote monitoring to molecular spectroscopy. Here, two polar crystals Ca3(TeO3)2(MO4) (M = Mo, W) were grown from TeO2-MO3flux by high-temperature solution methods. Ca3(TeO3)2(MoO4) and Ca3(TeO3)2(WO4) are isostructural, which feature novel structures consisting of asymmetric MO4tetrahedra and TeO3trigonal pyramids. Optical characterizations show that both crystals display ultrawide transparency ranges (279 nm to 5.78 μm and 290 nm to 5.62 μm), especially high optical transmittance over 80% in the important atmospheric transparent window of 3–5 μm, and superhigh laser damage thresholds (1.63 GW/cm2and 1.50 GW/cm2), 54.3 and 50 times larger than that of state-of-the-art MIR NLO AgGaS2, respectively. Notably, they exhibit the widest band gaps and the loftiest laser-induced threshold damages among the reported tellurates so far. Moreover, Ca3(TeO3)2(MO4) exhibit type I phase matching at two working wavelengths owing to their large birefringence and strong second-harmonic generation responses from the distorted anions, as further elucidated by the first-principles calculations. The above characteristics indicate that Ca3(TeO3)2(MO4) crystals are high-performance MIR NLO materials, especially applying in high-power MIR laser operations.

The success of artificial intelligence (AI) models has been limited by the requirement of large amounts of high-quality training data, which is just the opposite of the situation in most drug discovery pipelines. Active learning (AL) is a subfield of AI that focuses on algorithms that select the data they need to improve their models. Here, we propose a two-phase AL pipeline and apply it to the prediction of drug oral plasma exposure. In phase I, the AL-based model demonstrated a remarkable capability to sample informative data from a noisy data set, which used only 30% of the training data to yield a prediction capability with an accuracy of 0.856 on an independent test set. In phase II, the AL-based model explored a large diverse chemical space (855K samples) for experimental testing and feedback. Improved accuracy and new highly confident predictions (50K samples) were observed, which suggest that the model’s applicability domain has been significantly expanded.

Cyanurate crystals have recently become a research hot spot in birefringent materials owing to the large structural and optical anisotropy of the planar π-conjugated (HxC3N3O3)x−3(x= 0–3) groups. In this study, two new Zn-based cyanurate crystals, Zn5(OH)4(C3N3O3)2and MgZn4(OH)4(C3N3O3)2, were synthesized by the hydrothermal method. In Zn5(OH)4(C3N3O3)2, the d10Zn2+cations have three different coordinating environments, which has never been found in cyanurates. These compounds have wide band gaps (∼5 eV) and large birefringence (∼0.32 at 400 nm), indicating their potential as ultraviolet birefringence crystals.

The hollow carbon spheres loaded with Pd/Pd4S heterostructure (Pd/Pd4S@HCS) could promote the composition and decomposition of toroid-like discharge product with the efficient bi-functional catalytic activity.

Combining the advantages of organic and inorganic motifs, organic–inorganic hybrid materials can exhibit excellent nonlinear optical (NLO) performance. In this article, through systematic first-principles modeling and simulations, we investigated the NLO performance of an organic planar conjugated guanidinium cation [C(NH2)3+, guanidinium (GU)] and its hybrid materials with various inorganic anionic groups. It is demonstrated that GU-based hybrid materials are excellent candidates for ultraviolet (UV) NLO conversion, especially for the important 266 nm laser output in the solar-blind region, because of their wide UV transparency, strong second harmonic generation (SHG) effect, and large optical birefringence. Moreover, the UV NLO performance can be regulated by the hybrid strength and/or hybrid pattern between the GU cations and different kinds of inorganic anionic groups, which would help to explore new UV NLO materials in the hybrid material system.

Diffractive optics can be used to accurately control optical wavefronts, even in situations where refractive components such as lenses are not available. For instance, conventional Fresnel zone plates (ZPs) enable focusing of monochromatic radiation. However, they lead to strong chromatic aberrations in multicolor operation. In this work, we propose the concept of spatial entropy minimization as a computational design principle for both mono- and polychromatic focusing optics. We show that spatial entropy minimization yields conventional ZPs for monochromatic radiation. For polychromatic radiation, we observe a previously unexplored class of diffractive optical elements, allowing for balanced spectral efficiency. We apply the proposed approach to the design of a binary ZP, tailored to multispectral focusing of extreme ultraviolet (EUV) radiation from a high-harmonic tabletop source. The polychromatic focusing properties of these ZPs are experimentally confirmed using ptychography. This work provides a new route towards polychromatic wavefront engineering at EUV and soft-x-ray wavelengths.

AbstractSpinosad (spinosyn A and spinosyn D), the secondary metabolite produced by Saccharopolyspora spinosa,is a potent insecticide with low effects on the environment and mammals. Strategies such as metabolic engineering, mutagenesis and fermentation process optimization have been employed for its production enhancement. Quantitative real-time polymerase chain reaction(qRT-PCR) is one of the preferred methods for the evaluation of gene transcript levels, whose accuracy and sensitivity depend on the normalization using optimal reference genes. However, no single reference gene is universally appropriate for all strains under various conditions. In this study, the transcriptional stability of 35 candidate reference genes, including 23 traditionally used reference genes and 12 novel reference genes identified in S. spinosahomologous species, was analysed in S. spinosaATCC 49460 and spinosad high-yield strain S. spinosaS3-3 under three fermentation phases. The transcriptional stability of these genes was assessed by three statistical algorithms, geNorm, NormFinder and BestKeeper. The overall rankings suggested that rpoBand efpwere the most stable candidate reference genes, and they may be the most promising reference genes for further study on the measurement of expression levels of target genes involved in the biosynthetic process of spinosad.

The interplay between topology and correlations can generate a variety of quantum phases, many of which remain to be explored. Recent advances have identified monolayer WTe2as a promising material for doing so in a highly tunable fashion. The ground state of this two-dimensional crystal can be electrostatically tuned from a quantum spin Hall insulator to a superconductor. However, much remains unknown about the gap-opening mechanism of the insulating state. Here we report evidence that the quantum spin Hall insulator is also an excitonic insulator, arising from the spontaneous formation of electron–hole bound states, namely excitons. We reveal the presence of an intrinsic insulating state at the charge neutrality point in clean samples and confirm the correlated nature of this charge-neutral insulator by tunnelling spectroscopy. We provide evidence against alternative scenarios of a band insulator or a localized insulator and support the existence of an excitonic insulator phase in the clean limit. These observations lay the foundation for understanding a new class of correlated insulators with nontrivial topology and identify monolayer WTe2as a promising candidate for exploring quantum phases of ground-state excitons.

Reducing the energy bandwidth of electrons in a lattice below the long-range Coulomb interaction energy promotes correlation effects. Moiré superlattices—which are created by stacking van der Waals heterostructures with a controlled twist angle1–3—enable the engineering of electron band structure. Exotic quantum phases can emerge in an engineered moiré flat band. The recent discovery of correlated insulator states, superconductivity and the quantum anomalous Hall effect in the flat band of magic-angle twisted bilayer graphene4–8has sparked the exploration of correlated electron states in other moiré systems9–11. The electronic properties of van der Waals moiré superlattices can further be tuned by adjusting the interlayer coupling6or the band structure of constituent layers9. Here, using van der Waals heterostructures of twisted double bilayer graphene (TDBG), we demonstrate a flat electron band that is tunable by perpendicular electric fields in a range of twist angles. Similarly to magic-angle twisted bilayer graphene, TDBG shows energy gaps at the half- and quarter-filled flat bands, indicating the emergence of correlated insulator states. We find that the gaps of these insulator states increase with in-plane magnetic field, suggesting a ferromagnetic order. On doping the half-filled insulator, a sudden drop in resistivity is observed with decreasing temperature. This critical behaviour is confined to a small area in the density–electric-field plane, and is attributed to a phase transition from a normal metal to a spin-polarized correlated state. The discovery of spin-polarized correlated states in electric-field-tunable TDBG provides a new route to engineering interaction-driven quantum phases.

Structures composed of SiOxF6–x(x= 1, 2, 3, 4, 5) or SiOxF4–x(x= 1, 2, 3) species have thus far been observed in only a few compounds, and their functional properties are completely unknown in silicate chemistry. By introducing the least electronegative element, cesium, and the most electronegative element, fluorine, into the silicophosphate system, we successfully designed the first noncentrosymmetric fluorooxosilicophosphate with Si–F bonds, CsSiP2O7F, whose structure consists of an unprecedented SiP2O10F moiety containing hexacoordinate SiO5F species. The experimental results highlight CsSiP2O7F as the first fluorooxosilicophosphate deep-UV nonlinear optical (NLO) material. The first-principles calculations reveal that the SiP2O10F moiety is a new type of NLO-active unit and that both cesium and fluorine increase the deep-UV transparency of CsSiP2O7F. This work provides a new source of deep-UV NLO materials and insights into obtaining noncentrosymmetric structures that are indispensable to functional materials in nonlinear optics, piezoelectricity, ferroelectric, pyroelectricity, etc.

Harvesting energy from the environment offers the promise of clean power for self-sustained systems1,2. Known technologies—such as solar cells, thermoelectric devices and mechanical generators—have specific environmental requirements that restrict where they can be deployed and limit their potential for continuous energy production3–5. The ubiquity of atmospheric moisture offers an alternative. However, existing moisture-based energy-harvesting technologies can produce only intermittent, brief (shorter than 50 seconds) bursts of power in the ambient environment, owing to the lack of a sustained conversion mechanism6–12. Here we show that thin-film devices made from nanometre-scale protein wires harvested from the microbe Geobacter sulfurreducenscan generate continuous electric power in the ambient environment. The devices produce a sustained voltage of around 0.5 volts across a 7-micrometre-thick film, with a current density of around 17 microamperes per square centimetre. We find the driving force behind this energy generation to be a self-maintained moisture gradient that forms within the film when the film is exposed to the humidity that is naturally present in air. Connecting several devices linearly scales up the voltage and current to power electronics. Our results demonstrate the feasibility of a continuous energy-harvesting strategy that is less restricted by location or environmental conditions than other sustainable approaches.

A series of silver (Ag)-modified barium cobalt ferrous niobate (Ba1–xCo0.7Fe0.2Nb0.1O3-δ, BCFN) materials were fabricated using a solid-state method by doping silver cations into the A-site of this perovskite matrix (Ag-BCFN). The electrochemical analyses indicated that the Ag-BCFN cathodic catalysts performed superior to the nonmodified catalysts when applied in intermediate-temperature solid oxide fuel cells (IT-SOFCs). These Ag-BCFN cathodic catalysts displayed a cubic perovskite structure (PDF 75-0227, Pm3̅m, α = 90°) with a high degree of crystallinity, as demonstrated by X-ray powder diffraction analyses. It was also found that the in situexsolution of the silver ion (Ag+) occurred, where 57.9% of doped Ag+was reduced into metallic Ag particles with size ranging from 5 to 10 nm, as shown by electron microscopic analyses. The cerium gadolinium oxide (Ce0.9Gd0.1O2−δ) electrolyte-supported symmetrical half cell using different Ag-BCFN formulations of Ba1–xAgxCo0.7Fe0.2Nb0.1O3-δas electrodes showed a polarization resistance as low as 0.233 Ω·cm2and an exchange current density of 85.336 mA·cm–2at 650 °C under ambient pressure. The improved electrochemical kinetics is anticipated to be attributed to two reasons: doping of ions (Ag+) in the A-site of perovskite and in situexsolved silver nanoparticles (Ag NPs) along the edge and on the surface of BCFNs improving the mobile charge and electrical properties of the material. The remaining Ag+in the A-site induced the electron redistribution, whereas the Ag NPs were found to increase the electrochemically active sites and enable the formation of a triple-phase boundary. These explanations were confirmed by the density functional theory study, indicating that Ag-doping processes lead to a decrease in the formation energy of oxygen vacancies from 1.72 to 1.42 eV upon the partial substitution of Ba2+by Ag+cations.