118,352 research outputs found

    Highly hydrophobic zeolite ZSM-8 with perfect framework structure obtained in a strongly acidic medium

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    International audienceThe synthesis of zeolites in a strongly acidic medium is a new and nearly unexplored chemistry field. In addition to the previously reported silicalite-1 and the several clathrasils, this paper elaborates that one more material of unique properties could be successfully crystallized in the strongly acidic fluoride medium. A pure-silica zeolite ZSM-8 has been obtained using tetraethylammonium ion as a structure-directing agent. Rietveld refinement proves that ZSM-8 is of the MFI topology, i.e., it is another silicalite-1 but different in framework distortions. Moreover, the discrete and uniform crystals of the acidic-medium synthesized pure-silica ZSM-8 possess a substantially perfect framework structure and thus hydrophobic surfaces. This remarkable character renders the material an ideal adsorbent for discriminating molecules on the polarity basis, which is desired in developing green separation processes. C3H8, CH4, and CO2 are chosen as examples respecting their different polarities and tested for the adsorptive parameters

    Internal and external co-induction pineal 3D printed scaffolds for bone and blood vessel regeneration

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    The precise structural design and reproducible manufacturing advantages of the 3D printed scaffold make it attract attention in clinical applications. However, the inability of scaffolds to achieve internal and external co-induced vascularized osteogenesis limits their application. After observing the ingenious and functionalized structural combination of ''pinecone'', this study prepared hydrogel microspheres encapsulating strontium ranelate (SrR)-dendrimer (PAMAM) as a functionalized ''pine nuts'' through microfluidic technology. The 3D-printed Polycaprolactone (PCL) scaffold was used as a framework in which hydrogel microspheres and a 3D-printed scaffold were cleverly combined. In this pinecone 3D-scaffold system, the slow release of SrR is beneficial to promote vascularization and osteogenic differentiation inside and outside the scaffold. Furthermore, the rat femoral defect model verified that the pinecone scaffold promoting the formation of internal vascular network, osteogenic differentiation and shortening the bone repair time in vivo. In summary, this pinecone degradable biomimetic composite scaffold with internal osteogenic differentiation and vascular activation functions has great potential for clinical demand in segmental bone defects

    Characterization of Various Noncovalent Polyphenol–Starch Complexes and Their Prebiotic Activities during <i>In Vitro</i> Digestion and Fermentation

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    This study explores the structural characterization of six noncovalent polyphenol–starch complexes and their prebiotic activities during in vitro digestion and fermentation. Ferulic acid, caffeic acid, gallic acid, isoquercetin, astragalin, and hyperin were complexed with sweet potato starch (SPS). The polyphenols exhibited high binding capacity (>70%) with SPS. A partial release of flavonoids from the complexes was observed via in vitro digestion, while the phenolic acids remained tightly bound. Molecular dynamics (MD) simulation revealed that polyphenols altered the spatial configuration of polysaccharides and intramolecular hydrogen bonds formed. Additionally, polyphenol–SPS complexes exerted inhibitory effects on starch digestion compared to gelatinized SPS, owing to the increase in resistant starch fraction. It revealed that the different complexes stimulated the growth of Lactobacillus rhamnosus and Bifidobacterium bifidum, while inhibiting the growth of Escherichia coli. Moreover, in vitro fermentation experiments revealed that complexes were utilized by the gut microbiota, resulting in the production of short-chain fatty acids and a decrease in pH. In addition, the polyphenol–SPS complexes altered the composition of gut microbiota by promoting the growth of beneficial bacteria and decreasing pathogenic bacteria. Polyphenol–SPS complexes exhibit great potential for use as a prebiotic and exert dual beneficial effects on gut microbiota

    Bimetallic Oxide of Y<sub>2</sub>Cu<sub>2</sub>O<sub>5</sub> for Electroreduction of CO<sub>2</sub> to Syngas

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    The incorporation of guest elements into Cu-based bimetallic oxides has been proven as an effective way to modify the electronic structure and reactivity of Cu active sites. Here, the Y element was chosen as the guest element to modulate the electronic structure of Cu and alter its performance for electrochemical CO2 reduction reaction (CO2RR). Y2Cu2O5, a high-crystallinity Cu-based bimetallic oxide, was synthesized via the sol–gel method. For pure-phase CuO and Y2O3 controls, the selectivity of H2 significantly exceeded that of CO. While Y and Cu combined in equal molar weights to form Y2Cu2O5, a notable enhancement in the CO selectivity was observed, resulting in a CO/H2 ratio of approximately 1:1. These results prove that under the influence of Y, the electronic structure of Cu exhibits heightened CO selectivity. When the electrolyte solution was substituted with 1 M KOH, the CO/H2 ratio achieved was about 2:1, indicating that the ratio of syngas can be adjusted by changing the concentration or type of electrolyte. This study explores the electronic modulation of a guest element in Cu-based bimetallic oxides and clarifies the beneficial influence of the Y element on the activity of Cu sites, which provides a novel approach for designing and regulating the activity of catalyst active sites

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    Acoustic emission amplitude-frequency characteristics of similar materials: (a) ratio 1 (b) ratio 2 (c) ratio 3.</p

    Physical performance parameters of rock samples.

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    Using spline interpolation to select proportions of similar materials, a comparative analysis of the fracturing behavior of sandstone specimens and similar material specimens was conducted through Brazilian splitting tests under multi-path loading. The study revealed that during stepwise loading, both sandstone and similar materials exhibited memory effects and plastic deformation. However, under constant velocity loading, the relationship between force and displacement in sandstone showed linearity after compaction. Employing MATLAB optimization algorithms for the inversion of acoustic emission event information, the distribution of fracture points, and the evolution of cracks were analyzed. The findings indicated that under stepwise loading, both sandstone and similar materials exhibited banded distribution of peak frequencies, with sandstone concentrated in the mid-low-frequency range and similar materials leaning towards the low-frequency range. The amplitude-frequency characteristics of acoustic emission signals suggested that initially, sandstone produced low-frequency, low-amplitude signals. As cracks developed, these signals gradually transformed into high-frequency, high-amplitude signals, ultimately leading to macroscopic failure. The ringing counts and b-values of sandstone displayed an approximate "W" shape distribution, with a subsequent decrease in b-values during final failure. In contrast, the acoustic emission counts were inversely related to b-values. Similar materials exhibited slightly more acoustic emission counts than sandstone, with relatively lower b-values. The crack development process of both sandstone and similar materials was confirmed through these observations. From the perspective of section initiation and local damage, sandstone and similar materials exhibited similar failure characteristics. The proportions of quartz sand: cement: water = 9:1:0.9 in similar materials demonstrated the most similar characteristics to sandstone in terms of mechanical loading, acoustic emission features, and failure morphology. This suggests that these similar materials can be used as substitutes for sandstone in analogous simulation experiments. The study provides theoretical support for understanding rock fracture mechanisms, offers guidance for the selection and proportioning of similar materials, and holds significance for predicting and controlling rock fracture behavior in engineering applications.</div

    Mn-Doped M<sub>2</sub>CdCl<sub>4</sub> (M = CH<sub>3</sub>NH<sub>3</sub><sup>+</sup>, C<sub>2</sub>H<sub>8</sub>N<sup>+</sup>, and C<sub>3</sub>H<sub>10</sub>N<sup>+</sup>) Layered Hybrid Perovskite and Its Flexible Film Based on Simple Mechanochemical Synthesis

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    Layered hybrid perovskites show significant advantages in the field of optoelectronics. However, the low quantum efficiency and complex preparation methods limit their applications. In this work, we developed a series of perovskite powders with a two-dimensional (2D) layered structure of organic–inorganic hybrid metal halides M2CdCl4:x%Mn (M = CH3NH3+, C2H8N+, C3H10N+) via facile mechanochemical methods. The prepared manganese Mn-doped MA2CdCl4 produces orange emission at 605 nm under both 254 and 420 nm excitation, which originates from a dual excitation channel competition mechanism, and its excitation channel could be changed with the increase of Mn2+ ion concentration. Typically, MA2CdCl4:20%Mn powder exhibits high photoluminescence quantum yield (PLQY) close to 90% at 605 nm due to the organic amine ions enlarging the Mn–Mn interlayer distances. In addition, we prepared MA2CdCl4:x%Mn@PVA flexible films, which also exhibit good luminescence at 254 nm excitation and were unexpectedly found to have a better response to Cs+, which could be a candidate for anticounterfeiting applications

    Impact of lockdown on the growth of children in China aged 3-6 years during the COVID-19 pandemic

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    BackgroundLockdowns in COVID-19 pandemic led to less physical activity and more intake of unhealthy food in children. The aim of this study was to investigate the negative impact of major lockdowns on the growth of children aged 3-6 years during COVID-19 pandemic period.MethodsPhysical examination results in 2019 to 2022 from 5834 eligible children (2972 males and 2862 females) from Southwestern China who were 3 years old in 2019 were retrospectively collected. Height and weight data points were extracted from the results, and percentiles of height (height%), weight (weight%), and BMI (BMI%), and rates of overweight and obesity were calculated and compared between different years during the pandemic.ResultsAfter analyzing the 15404 growth data points from 5834 children, a slowly increasing trend of height% from 2019 to 2022 was observed. Weight%, BMI%, overweight rate, obesity rate, and combined overweight and obesity rate had two peaks in 2020 and 2022 when major lockdowns were adopted and a drop in between (year 2021), except for obesity rate which did not drop in 2021. Similar results were shown after stratification by gender.ConclusionThe lockdowns in COVID-19 pandemic promoted obesity of kindergarten children, but did not show any negative impact on their height growth possibly due to over-nutrition of children during lockdowns. More efforts need to be made to limit the increase of obesity rate in kindergarten children during possible future lockdowns

    Local Scaffold Diversity-Contributed Generator for Discovering Potential NLRP3 Inhibitors

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    Deep generative models have become crucial tools in de novo drug design. In current models for multiobjective optimization in molecular generation, the scaffold diversity is limited when multiple constraints are introduced. To enhance scaffold diversity, we herein propose a local scaffold diversity-contributed generator (LSDC), which can be utilized to generate diverse lead compounds capable of satisfying multiple constraints. Compared to the state-of-the-art methods, molecules generated by LSDC exhibit greater diversity when applied to the generation of inhibitors targeting the NOD-like receptor (NLR) family, pyrin domain-containing protein 3 (NLRP3). We present 12 molecules, some of which feature previously unreported scaffolds, and demonstrate their reasonable docking binding modes. Consequently, the modification of selected scaffolds and subsequent bioactivity evaluation lead to the discovery of two potent NLRP3 inhibitors, A22 and A14, with IC50 values of 38.1 nM and 44.43 nM, respectively. And the oral bioavailability of compound A14 is very high (F is 83.09% in mice). This work contributes to the discovery of novel NLRP3 inhibitors and provides a reference for integrating AI-based generation with wet experiments