Qiao Lin

This paper presents the optimization of surface modification for aptameric graphene nanosensors for the measurement of biomarkers in undiluted physiological media. In these sensors, graphene transduces the binding between an aptamer and the intended target biomarker into a measurable signal while being coated with a polyethylene glycol (PEG) nanolayer to minimize nonspecific adsorption of matrix molecules. We perform a systematic study of the aptamer and PEG attachment schemes and parameters, including the impact of the serial or parallel PEG-aptamer attachment scheme, PEG molecular weight and surface density, and aptamer surface density on the sensor behavior, such as the responsivity to biomarker concentration changes, and importantly, they are used for operation in physiological media and have the ability to reject nonspecific binding to interfering molecules. We then use the understanding from this parametric study to identify graphene nanosensor designs that are optimally functionalized with PEG and aptamers to be strongly responsive to target biomarkers and effectively reduce nonspecific adsorption of interferents, thereby enabling sensitive and specific biomarker measurements in undiluted physiological media. The experimental results show that nanosensors that were optimized via serial modification with 5000 Da PEG at 15 mM and a 94 nt DNA aptamer at 500 nM allowed specific measurement of C-reactive protein (CRP) in undiluted human serum with a limit of detection (LOD) down to 27 pM, representing an up to 1000-fold improvement compared to previously reported CRP measurements.

The severe shuttle effect of polysulfides for high-performance lithium–sulfur (Li–S) batteries leads to poor reversibility and cyclability at high rates, greatly hindering their practical applications. Here, we design a Phyllostachys edulis -derived microporous carbon–sulfur (denoted as MPC@S) cathode with physical nanoconfinement and chemical C–S bonding for high-rate Li–S batteries. The high pore volume can physically confine sulfur and polysulfides into microporous carbon to achieve good structural stability of the electrode during cycling. Moreover, the strong chemical C–S bonding interaction between MPC and sulfur can effectively improve the utilization of the active material and enhance redox reaction kinetics at high rates. Due to the synergistic combination of physical and chemical confinement of sulfur and polysulfides, the Li–S battery with MPC@S cathode delivers an initial specific discharge capacity of 1070.06 mAh g –1 at 167.5 mA g –1 and achieves good cyclability with a high average Coulombic efficiency of >97.88% at 1675 mA g –1 for 500 cycles with a low decay rate of 0.0912% per cycle. This work provides a facile strategy for the large-scale fabrication of high-performance biomass-derived composite cathodes for high-rate Li–S batteries and brings deep insights into structure–property relationships of high-capacity electrodes for next-generation lithium batteries.

Tartary buckwheat dietary fiber (TBDF) was extracted from Tartary buckwheat husks via enzymatic hydrolysis, and the extraction process was optimized by response surface methodology. The optimal conditions were as follows: pH of 4.5, 16% enzyme concentration, and 10.5-h hydrolysis. To study its effects on metabolic health, different TBDF concentrations were added to mice’s drinking water for 5 weeks. Results showed that TBDF significantly inhibited weight gain in obese mice, reduced liver index and fat-to-body ratio, alleviated hepatic steatosis, and prevented excessive fat accumulation. Higher-concentration TBDF had more hypoglycemic effects. After the intervention, Illumina MiSeq high-throughput sequencing was used to analyze gut microbiota. Comparing fecal samples from four groups, TBDF supplementation was found to enrich gut microbiota, increasing the relative abundance of Bacteroidetes. At the genus level, beneficial bacteria, such as Roseburia, Enterococcus, and Lactobacillus, were promoted. In conclusion, TBDF improves metabolic parameters and gut microbiota, offering a new dietary fiber-based strategy for obesity and metabolic disorders.

OBJECTIVES: Staphylococcus pseudintermedius is a major pathogen of canine pyoderma, and its increasing antimicrobial resistance poses a potential threat to public health, making it crucial to explore the development of new alternative therapeutic agents. METHODS AND RESULTS: In this study, we investigated the in vitro antimicrobial activity and mechanism of inhibition of sanguinarine (SAN) against clinically resistant bacteria. In addition, a murine methicillin-resistant Staphylococcus pseudintermedius (MRSP) skin infection model was established to evaluate the therapeutic efficacy of SAN. In vitro assays revealed that the MIC and MBC of SAN against S. pseudintermedius were 39.06 μg˙mL-1 and 156.25 μg˙mL-1. SAN could delay MRSP entry into the logarithmic growth phase and disrupt the bacterial structure. Transcriptomic analysis revealed that SAN primarily impacted amino acid synthesis and metabolism. In a murine MRSP skin infection model, SAN significantly reduced bacterial load, increased serum IL-4 expression, and decreased IL-6 expression. Histopathological analysis showed reduced inflammation and improved skin structure in the SAN group, with abundant fibroblasts and macrophages. CONCLUSIONS: These results reveal that SAN can inhibit the growth of MRSP, the primary drug-resistant strain associated with canine pyoderma, and suggests SAN's potential as a therapeutic option to counteract the emergence of antimicrobial resistance.

Abstract Polymer and many other flows exhibit non‐Newtonian rheological behavior. For some materials, the thermal dependence of viscosity is also essential to be established. It can be described by considering an activation energy, estimated by using the viscosity measurements at different temperatures. Nevertheless, the test temperatures must be reliable and accurate. An annular measuring device (TRAC: Thermo‐Rheo Annular Cell) is previously proposed for highly robust temperature measurement and viscosity identification by inverse method, which exploits the viscous dissipation in the flow. This work explains how critical viscosity points, identified thanks to the TRAC, can be used to estimate the activation energy with different approaches involving the principle of time‐temperature superposition. Thanks to the thermal characteristics of the annular flow, the thermal dependence of viscosity can also be estimated from direct temperature measurements to perform fast analysis, without using inverse method.

With the development of nuclear magnetic resonance (NMR) spectrometers and probes, two-dimensional quantitative nuclear magnetic resonance (2D qNMR) technology with a high signal resolution and great application potential has become increasingly accessible for the quantitation of complex mixtures. However, the requirement that the relaxation recovery time be equal to at least five times T 1 (longitudinal relaxation time) makes it difficult for 2D qNMR to simultaneously achieve high quantitative accuracy and high data acquisition efficiency. By comprehensively using relaxation optimization and nonuniform sampling, we successfully established an optimized 2D qNMR strategy for HSQC experiments at the half-hour level and then accurately quantified the diester-type C 19 -diterpenoid alkaloids in Aconitum carmichaelii . The optimized strategy had the advantages of high efficiency, high accuracy, good reproducibility, and low cost and thus could serve as a reference to optimize 2D qNMR experiments for quantitative analysis of natural products, metabolites, and other complex mixtures.

Abstract. There are always debates on the use of power law to model flows having a local zero shear rate. This paper uses an original method to define a functional shear rate range with respect to the flow condition and identify an equivalent power law from a Cross-law fluid. The numerical and experimental results are compared to show the ability of the power law to model a flow having a low-shear region.

International audience

Dans le cadre de l'identification de la viscosité en ligne, où le débit de l'écoulement est imposé par les paramètres de processus, des études récentes ont proposé différentes approches pour obtenir plus d'informations sur la rhéologie du fluide sans modifier les conditions de production. Une des démarches est d'utiliser la dissipation visqueuse et la convection. La dissipation visqueuse est provoquée par le cisaillement au sein de l'écoulement. La convection entre l'écoulement et une surface de paroi est aussi corrélée au profil de vitesse de l'écoulement, qui dépend de la courbe de viscosité du fluide. Différente de la méthode conventionnelle qui utilise des capteurs de pression pour identifier une viscosité apparente à la paroi d'un écoulement pour un débit donné, la démarche thermique apporte plus d'informations sur une certaine profondeur de l'écoulement par rapport à la paroi. Les premiers travaux réalisés ont permis de mettre au point une cellule de mesure thermo-rhéologique à mettre en ligne dans un procédé de mise en œuvre de type extrusion ou injection des matériaux polymères. Imposant un écoulement annulaire dans ce dispositif instrumenté, nous montrons qu'à partir des mesures de température à l'axe central du conduit, la variation de la température due à la dissipation visqueuse à un débit constant permet d'indiquer un point critique sur la courbe de viscosité du fluide. De plus, l'échange par convection entre l'écoulement de polymère et l'axe central est sensible à l'indice de pseudo-plasticité du polymère, décrit par une loi de puissance. La loi de puissance en échelle logarithmique est en effet une droite ayant une pente constante définie par l'indice de pseudo-plasticité. Cependant, les polymères ont un comportement pseudo-plastique à taux de cisaillement élevé et un comportement Newtonien à faible taux de cisaillement, c'est-à-dire que la pente de la courbe de viscosité en échelle logarithmique varie et tend vers zéro quand le taux de cisaillement tend vers zéro. Dans ce papier, des simulations numériques de l'écoulement annulaire d'un polypropylène sont réalisées. Le comportement rhéologique du polymère est modélisé par une loi de Cross. Des identifications virtuelles à partir des « mesures » simulées sont également effectuées. Les points critiques identifiés à différents débits se retrouvent sur la loi de Cross à différents taux de cisaillement. Les indices de pseudo-plasticité identifiés à différents débits sont en effet corrélés à la pente de la courbe de viscosité, aux points critiques obtenus aux mêmes débits. Le résultat de cette étude montre qu'il est possible d'utiliser la démarche thermique pour identifier une zone de fonctionnement (liée à un débit donné) sur une courbe de viscosité complexe, et de décrire cette zone par une loi de puissance locale (point critique + pente), pour l'identification de la viscosité en ligne de production des polymères.