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Crystal engineering of metal−organic frameworks (MOFs) has allowed the construction of complex structures at atomic precision, but has yet to reach the same level of sophistication as organic synthesis. The synthesis of complex MOFs with multiple organic and/or inorganic components is ultimately limited by the lack of control over framework assembly in one-pot reactions. Herein, we demonstrate that multi-component MOFs with unprecedented complexity can be constructed in a predictable and stepwise manner under simple kinetic guidance, which conceptually mimics the retrosynthetic approach utilized to construct complicated organic molecules. Four multi-component MOFs were synthesized by the subsequent incorporation of organic linkers and inorganic clusters into the cavity of a mesoporous MOF, each composed of up to three different metals and two different linkers. Furthermore, we demonstrated the utility of such a retrosynthetic design through the construction of a cooperative bimetallic catalytic system with two collaborative metal sites for three-component Strecker reactions. The crystal engineering of metal–organic frameworks has led to the construction of complex structures, but has yet to reach the same level of sophistication as organic synthesis. Here, Zhou and colleagues use retrosynthetic chemistry to design and produce complex multi-component frameworks.

A major goal of metal–organic framework (MOF) research is the expansion of pore size and volume. Although many approaches have been attempted to increase the pore size of MOF materials, it is still a challenge to construct MOFs with precisely customized pore apertures for specific applications. Herein, we present a new method, namely linker labilization, to increase the MOF porosity and pore size, giving rise to hierarchical-pore architectures. Microporous MOFs with robust metal nodes and pro-labile linkers were initially synthesized. The mesopores were subsequently created as crystal defects through the splitting of a pro-labile-linker and the removal of the linker fragments by acid treatment. We demonstrate that linker labilization method can create controllable hierarchical porous structures in stable MOFs, which facilitates the diffusion and adsorption process of guest molecules to improve the performances of MOFs in adsorption and catalysis. Expanding pore sizes and volumes in metal-organic frameworks is challenging, but crucial for the encapsulation of larger guest molecules. Here, Zhou and colleagues report a linker labilization strategy to construct MOFs containing hierarchical pore architectures with dimensions ranging from 1.5 to 18 nm.

Human visual recognition activates a dense network of overlapping feedforward and recurrent neuronal processes, making it hard to disentangle processing in the feedforward from the feedback direction. Here, we used ultra-rapid serial visual presentation to suppress sustained activity that blurs the boundaries of processing steps, enabling us to resolve two distinct stages of processing with MEG multivariate pattern classification. The first processing stage was the rapid activation cascade of the bottom-up sweep, which terminated early as visual stimuli were presented at progressively faster rates. The second stage was the emergence of categorical information with peak latency that shifted later in time with progressively faster stimulus presentations, indexing time-consuming recurrent processing. Using MEG-fMRI fusion with representational similarity, we localized recurrent signals in early visual cortex. Together, our findings segregated an initial bottom-up sweep from subsequent feedback processing, and revealed the neural signature of increased recurrent processing demands for challenging viewing conditions. The human brain can interpret the visual world in less than the blink of an eye. Specialized brain regions process different aspects of visual objects. These regions form a hierarchy. Areas at the base of the hierarchy process simple features such as lines and angles. They then pass this information onto areas above them, which process more complex features, such as shapes. Eventually the area at the top of the hierarchy identifies the object. But information does not only flow from the bottom of the hierarchy to the top. It also flows from top to bottom. The latter is referred to as feedback activity, but its exact role remains unclear. Mohsenzadeh et al. used two types of imaging to map brain activity in space and time in healthy volunteers performing a visual task. The volunteers had to decide whether a series of images that flashed up briefly on a screen included a face or not. The results showed that the brain adapts its visual processing strategy to suit the viewing conditions. They also revealed three key principles for how the brain recognizes visual objects. First, if early visual information is incomplete – for example, because the images appeared only briefly – higher regions of the hierarchy spend more time processing the images. Second, when visual information is incomplete, higher regions of the hierarchy send more feedback down to lower regions. This leads to delays in identifying the object. And third, lower regions in the hierarchy – known collectively as early visual cortex – process the feedback signals. This processing takes place at the same time as the higher levels identify the object. Knowing the role of feedback is critical to understanding how the visual system works. The next step is to develop computer models of visual processing. The current findings on the role of feedback should prove useful in designing such models. These might ultimately pave the way to developing treatments for visual impairments caused by damage to visual areas of the brain.

BackgroundOsteoarthritis (OA) is common and burdensome for patients and health care systems. Our study purpose was to evaluate the long-term efficacy and safety of DMOADs in adults with knee and hip osteoarthritis.MethodsWe searched Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and Web of Knowledge without language, publication, or date restrictions from inception through November 2018 for randomized controlled trials assessing 12 classes of DMOADs with at least 12 months of follow-up. Therapeutic effects were evaluated with pairwise and network meta-analysis. Outcomes included pain, function, minimum joint space width or cartilage volume, radiographic progression, and total joint replacement. Analyses were also performed for drug safety.ResultsTwenty-eight randomized controlled trials with 11,890 patients were included. Glucosamine and chondroitin minimally improved both structure (minimum joint width or cartilage volume: network results: glucosamine: SMD 0.16; 95% CI [0.04, 0.28], chondroitin: SMD 0.21 [0.10, 0.32]) and symptoms (glucosamine: pain: − 0.15 [− 0.25, − 0.05]; function: − 0.17 [− 0.28, − 0.07], chondroitin: pain: − 0.06 [− 0.15, 0.03], and function: − 0.15 [− 0.26, − 0.03]). Strontium demonstrated improvement in structure (minimum joint width or cartilage volume: 0.20 [0.02, 0.38]), and vitamin D on symptoms (pain: − 0.15 [− 0.27, -0.03]; function: − 0.18 [− 0.31, − 0.06]). Although doxycycline also demonstrated a favorable efficacy ranking, its safety profile was poor (withdrawal: network relative risk 1.69 [1.03, 2.75]). The therapeutic effects of other medications were not ranked as highly.DiscussionGlucosamine and chondroitin yielded statistically significant but clinically questionable long-term benefit on structure and symptoms, though both had favorable safety profiles. Strontium improved structure, and vitamin D improved symptoms. Although doxycycline had a favorable efficacy ranking, its safety profile was poor. None of the 12 classes of drugs appears to have long-term clinically significant benefit.

Deeply exhumed crustal terranes of continental arcs worldwide commonly contain metasedimentary components, but the nature of these lithologies and how they became incorporated into the lower crust are not fully understood. Here, we present petrological, geochemical and geochronological data from exhumed deep‐crustal metapelites and orthogneisses from the eastern Gangdese magmatic arc, southern Tibet. Geochemical and geochronological affinity between metapelites and forearc sediments indicates that their protoliths were probably deposited in an Early Cretaceous (<120 Ma) forearc basin of the Gangdese arc, while the orthogneisses represent metamorphosed equivalents of Late Jurassic (157–140 Ma) arc‐type magmatic rocks. Petrological modeling and zircon U‐Pb dating show that metapelites and orthogneisses simultaneously experienced high‐pressure granulite‐facies metamorphism at peak pressure‐temperature conditions of 810–840°C and 12–16 kbar at 87–85 Ma. Our findings suggest that both the Mesozoic forearc sediments and igneous rocks that were initially emplaced into the upper crust of the Gangdese arc were subsequently transported to its lower crust within c. 25 Myr by crustal shortening, folding and underthrusting during the Late Cretaceous. When combined with previous data collected from the region, we propose that tectonic burial within arc crust and slab subduction‐related mechanisms most likely operate together in magmatic arcs, promoting crustal recycling. The transport of surficial silica‐rich materials into the lower crust is likely a basic process that has driven the growth and differentiation of continental arcs throughout geological time.

Furanosteroids, represented by wortmannin, viridin, and demethoxyviridin, are a special group of fungal-derived, highly oxygenated steroids featured by an extra furan ring. They are well-known nanomolar-potency inhibitors of phosphatidylinositol 3-kinase and widely used in biological studies. Despite their importance, the biosyntheses of these molecules are poorly understood. Here, we report the identification of the biosynthetic gene cluster for demethoxyviridin, consisting of 19 genes, and among them 15 biosynthetic genes, including six cytochrome P450 monooxygenase genes, are deleted. As a result, 14 biosynthetic intermediates are isolated, and the biosynthetic pathway for demethoxyviridin is elucidated. Notably, the pregnane side-chain cleavage requires three enzymes: flavin-dependent Baeyer-Villiger monooxygenase, esterase, and dehydrogenase, in sharp contrast to the single cytochrome P450-mediated process in mammalian cells. Structure–activity analyses of these obtained biosynthetic intermediates reveal that the 3-keto group, the C1β–OH, and the aromatic ring C are important for the inhibition of phosphatidylinositol 3-kinase. Demethoxyviridin is a fungal steroid that inhibits a phosphatidylinositol 3-kinase, an enzyme contributing to tumor progression. Here, the authors elucidate the biosynthetic route that leads to the formation of demethoxyviridin in fungi.

Respiratory syncytial virus (RSV) infection is the most frequent cause of hospitalization in pediatric patients. Current systemic treatment and vaccines are not curative and re-infection is often associated with a more drastic incidence of the disease. Baicalin is a flavonoid isolated from Scutellaria baicalensis with potent anti-viral characteristics, namely against RSV. However, its precise mechanism of action remains unclear. Here, using in vitro methods and an in vivo murine model of RSV infection, we showed that baicalin inhibits RSV replication induces translational upregulation of type I interferons (IFNs), IFN-α and IFN-β, and reverses epithelial thickening in lung tissues. Moreover, baicalin inhibits transcription of the RSV non-structural proteins NS1 and NS2. Molecular docking and surface plasmon resonance-based affinity analysis showed that baicalin also binds to the α3 helix of the NS1 protein with an affinity constant of 1.119 × 10 −5 M. Polysome profiling showed that baicalin inhibits translation of the RSV matrix protein (M) RNA. Baicalin mediates increased release of the ribosomal protein L13a from the large ribosomal subunit, where the extra ribosomal subunit L13a inhibits M RNA translation. These results comprehensively establish the multiple mechanisms by which baicalin induces a potent innate immune response against RSV infection.

Transition metal‐nitrogen‐carbon (M‐N‐C) catalysts have emerged as promising candidates for electrocatalytic CO2 reduction reaction (CO2RR) due to their uniform active sites and high atomic utilization rate. However, poor efficiency at low overpotentials and unclear reaction mechanisms limit the application of M‐N‐C catalysts. In this study, Fe‐N‐C catalysts are developed by incorporating S atoms onto ordered hierarchical porous carbon substrates with a molecular iron thiophenoporphyrin. The well‐prepared FeSNC catalyst exhibits superior CO2RR activity and stability, attributes to an optimized electronic environment, and enhances the adsorption of reaction intermediates. It displays the highest CO selectivity of 94.0% at −0.58 V (versus the reversible hydrogen electrode (RHE)) and achieves the highest partial current density of 13.64 mA cm−2 at −0.88 V. Furthermore, when employed as the cathode in a Zn‐CO2 battery, FeSNC achieves a high‐power density of 1.19 mW cm−2 and stable charge–discharge cycles. Density functional theory calculations demonstrate that the incorporation of S atoms into the hierarchical porous carbon substrate led to the iron center becoming more electron‐rich, consequently improving the adsorption of the crucial reaction intermediate *COOH. This study underscores the significance of hierarchical porous structures and heteroatom doping for advancing electrocatalytic CO2RR and energy storage technologies. By utilizing a strategic combination of molecular metalloporphyrins (with a clear and modifiable structure) and heteroatom doping (enabling control over the microenvironment of active sites), atomically dispersed iron species confined within channel‐rich S‐doped nitrogen–carbon materials are synthesized. Electrochemical assessments and theoretical calculations indicate that FeSNC exhibits significant activity and selectivity in CO2 reduction reactions.

The main purpose of this article is to demonstrate that bursting oscillations can be exploited to enhance the harvested electrical power. A vibration-based bistable Duffing energy harvester, a tristable energy harvester and an asymmetric bistable energy harvester are examined, and bursting oscillations are observed in the energy-harvesting systems with periodic excitation when an order gap exists between the exciting frequency and the natural frequency. The bifurcation mechanism of the bursting oscillations is presented via the bifurcation diagram and the transformed phase portrait of fast subsystem, which reveals that fold bifurcations occur at the transition between the quiescent states and the repetitive spiking states. Then, we investigate the influence of resistive load on the output power, and the optimal resistance is employed to determine the maximum of the power. Furthermore, compared with the method of traditional resonance energy harvesting, results clearly illustrate an improved output power.

Industry 4.0, the fourth industrial revolution, focuses on intelligent and smart manufacturing. This article investigates a smart design performance measurement approach, which can be utilized to support performance measurement implementation during a collaborative design process. First, we develop a smart product design framework with Industry 4.0 enabling technologies to support key design stages in an iterative fashion. Second, based on this framework, we propose a smart design performance measurement approach to potentially support a smart product design project management via its performance management. Third, we adapt our existing design performance measurement, for a traditional design environment into a smart design environment at its early stage to test its feasibility. This approach features integration of a flexible performance measurement setup, a multi-feedback design performance measurement mechanism and a multiple design performance measurement results presentation which allows the design performance measurement approach to produce flexible and customized operations by connecting design performance measurement with the stage-based design objectives, balancing design performance measurement feedbacks through interoperability between collaborative design team members and providing real-time design performance measurement results to guide design activities. An empirical industrial evaluation case study indicates that the proposed design performance measurement approach can support design team members in improving their collaborative design performance.