Preparation of caffeic acid grafted chitosan self-assembled micelles to enhance oral bioavailability and antibacterial activity of quercetin

Quercetin (QR) is a naturally occurring flavonoid organic compound that has poor solubility in water and highly unstable in alkaline conditions, resulting in limited absorption in poultry. Consequently, in our experiment, QR was employed as a model compound, encapsulated within the caffeic acid graft chitosan copolymer (CA-g-CS) self-assembled micelles to enhance its solubility, stability and exhibit a synergistic antibacterial effect. The optimization of the formula was carried out using a combination of single-factor experimentation and the response surface method. The in vitro release rate and stability of CA-g-CS-loaded QR micelles (CA-g-CS/QR) in various pH media were studied and the pharmacokinetics in white feather broiler chickens was evaluated in vivo. Additionally, the antibacterial activity was investigated using Escherichia coliCMCC44102 and Escherichia coli of chicken origin as the test strain. The results showed the optimized formula for the self-assembled micelles were 4 mL water, 0.02 mg/mL graft copolymer, and 1 mg QR, stirring at room temperature. The encapsulation efficiency was 72.09%. The resulting CA-g-CS/QR was uniform in size with an average diameter of 375.6 ± 5.9 nm. The release pattern was consistent with the Ritger-Peppas model. CA-g-CS/QR also significantly improved the stability of QR in alkaline condition. The relative bioavailability of CA-g-CS/QR was found to be 1.67-fold that of the reference drug, indicating a substantial increase in the absorption of QR in the broiler. Compared to the original drug, the antibacterial activity of CA-g-CS/QR was significantly enhanced, as evidenced by a reduction of half in the MIC and MBC values. These results suggest that CA-g-CS/QR improves the bioavailability and antibacterial activity of QR, making it a promising candidate for clinical use

Ultrathin Magnesium-based Coating as an Efficient Oxygen Barrier for Superconducting Circuit Materials

Scaling up superconducting quantum circuits based on transmon qubits necessitates substantial enhancements in qubit coherence time. Among the materials considered for transmon qubits, tantalum (Ta) has emerged as a promising candidate, surpassing conventional counterparts in terms of coherence time. However, the presence of an amorphous surface Ta oxide layer introduces dielectric loss, ultimately placing a limit on the coherence time. In this study, we present a novel approach for suppressing the formation of tantalum oxide using an ultrathin magnesium (Mg) capping layer deposited on top of tantalum. Synchrotron-based X-ray photoelectron spectroscopy (XPS) studies demonstrate that oxide is confined to an extremely thin region directly beneath the Mg/Ta interface. Additionally, we demonstrate that the superconducting properties of thin Ta films are improved following the Mg capping, exhibiting sharper and higher-temperature transitions to superconductive and magnetically ordered states. Based on the experimental data and computational modeling, we establish an atomic-scale mechanistic understanding of the role of the capping layer in protecting Ta from oxidation. This work provides valuable insights into the formation mechanism and functionality of surface tantalum oxide, as well as a new materials design principle with the potential to reduce dielectric loss in superconducting quantum materials. Ultimately, our findings pave the way for the realization of large-scale, high-performance quantum computing systems

Facile Synthesis of Highly Active Mesoporous PdCeO_<i>x</i> Solid Solution for Low-Temperature CO Oxidation

A series of mesoporous PdCeO_<i>x</i> solid solution with high specific area was successfully fabricated through a facile coprecipitation and low-temperature calcination strategy. The resulting materials possessed excellent catalytic activities for CO oxidation. The complete CO conversion could be achieved at as low as 20 °C. The doping of palladium increased the concentration of structural oxygen vacancy which is beneficial for the CO oxidation reaction process. The CO oxidation reaction mechanism over PdCeO_<i>x</i> solid solution was proved through in situ DRIFTS analysis

Debris flow weakens the ecological role of river microhabitat heterogeneity in mountainous regions

Mountain rivers provide habitat or refuges and create migration corridors for diverse aquatic and riparian organisms. River microhabitat heterogeneity (RMH), which plays a key role in ecological restoration, is sensitive to external disturbances in mountain rivers. However, the effects of RMH, induced by hydro-geomorphological processes, on local macroinvertebrates have not been quantitatively studied. To explore the ecological significance of RMH, we proposed a new RMH index (RMHI) for quantitative evaluation of RMH and selected five debris flow-dominated mountain rivers (DMR) and five equilibrium sediment transport mountain rivers (EMR) as contrasting examples based on the richness of sediment supply. We found that RMH supported macroinvertebrate α-diversity and functional richness in both DMR and EMR, but debris flow weakened the ecological role of RMH in DMR. The proposed RMHI should be ≥ 8.0 to maintain the ecological health of mountain rivers. Besides, the macroinvertebrate communities were mainly driven by species turnover in EMR, while species turnover and nestedness were balanced in DMR. And macroinvertebrate community shift from an R-strategy to a K-strategy due to deposition and erosion. According to the research results, we put forward the following suggestions. At the watershed scale, ecological conservation of mountain rivers requires a regional approach focusing on multiple sites in EMR. Priority should be given to protect the river with high macroinvertebrate species richness and close attention needs to be paid to multiple sites of DMR. At the river scale, we can protect the biodiversity of mountain rivers by maintain RMHI above its threshold

Optimizing the surface distribution of acid sites for cooperative catalysis in condensation reactions promoted by water

Nature accomplishes catalytic process with exquisite control by altering the distribution of active sites in a confining pocket and by regulating the structure of occluded solvents. In such systems, the ubiquitous water may influence reaction rates and selectivity by stabilizing reaction intermediates and transition states via a network of H bonds. Inspired by nature, here we aim at providing quantitative support and mechanistic insight into the role of water-promoting C–C bond formation on an acid catalyst by combining spectroscopic analysis, catalytic reaction measurements, and theoretical calculations. This set of experimental and computational studies reveals that the interaction between water and polar species on the surface generates diverse environments surrounding the active sites that facilitate the reaction. These findings provide an extra dimension for tailoring catalytic phenomena in industrially relevant reactions.This is a manuscript of an article published as Li, Gengnan, Bin Wang, Takeshi Kobayashi, Marek Pruski, and Daniel E. Resasco. "Optimizing the surface distribution of acid sites for cooperative catalysis in condensation reactions promoted by water." Chem Catalysis 1, no. 5 (2021): 1065-1087. DOI: 10.1016/j.checat.2021.08.005. Copyright 2021 Elsevier Inc. DOE Contract Number(s): SC0018284; AC02-07CH11358. Posted with permission

Self-Templated Synthesis of Porous Ni(OH)₂ Nanocube and Its High Electrochemical Performance for Supercapacitor

Porous Ni­(OH)₂ nanocubes were successfully fabricated by a simple self-sacrificial-template protocol using Ni–Co Prussian blue analogue (PBA) as precursor. When treated with NaOH, the simultaneous corrosion of Ni–Co PBA precursor and formation of amorphous Ni­(OH)₂ resulted in porous Ni­(OH)₂ nanocubes with uniform size of about 100 nm. Due to the large specific surface area and unique regular porous structure, the as-prepared materials showed large specific capacitance, relatively stable rate capability and long cycle stability when used as electrode materials for supercapacitors. With the voltage between 0.00 and 0.45 V versus Ag/AgCl, the specific capacitance can achieve 1842 F/g at a current density of 1 A/g

Highly Efficiently Delaminated Single-Layered MXene Nanosheets with Large Lateral Size

Single layered Ti₃C₂(OH)₂ nanosheets have been successfully fabricated by etching its Ti₃AlC₂ precursor with KOH in the presence of a small amount of water. The OH group replaced the Al layer within the Ti₃AlC₂ structure during etching, and Ti₃C₂(OH)₂ nanosheets could be easily and efficiently achieved through a simple washing process. The delaminated single-layered nanosheets are clearly revealed by atomic force microscopy to be several micrometers in lateral size. Interestingly, the exfoliated Ti₃C₂(OH)₂ nanosheets could be restacked to form a new layer-structured material after drying. When redispersing this restacked Ti₃C₂(OH)₂ materials in water again, it could be re-delaminated easily only after shaking for several hours. The easy delamination and restacking properties, coupled with intrinsic metallic conductivity and hydrophilicity, make it an ideal two-dimensional building block for fabricating a wide variety of functional materials

Energetic Cost for Being “Redox-Site-Rich” in Pseudocapacitive Energy Storage with Nickel – Aluminum Layered Double Hydroxide Materials

Defining the energetic landscape of pseudocapacitive materials such as transition metal layered double hydroxides (LDHs) upon redox site enrichment is essential to harness their power for effective energy storage. Here, coupling acid solution calorimetry, in situ XRD, and in situ DRIFTS, we demonstrate that as the Ni/Al ratio increases, both as-made (hydrated) and dehydrated NiAl-LDH samples are less stable evidenced by their enthalpies of formation. Moreover, the higher specific capacity at intermediate Ni/Al ratio of 3 is enabled by effective water – LDH interactions, which energetically stabilizes the excessive near-surface Ni redox sites, solvates intercalated carbonate ions, and fills the expanded vdW gap, paying for the “energetic cost” of being “redox site rich”. Thus, from a thermodynamic perspective, engineering molecule/solids – LDH interactions on the nanoscale with confined guest species other than water, which energetically impose stronger stabilization, may help us to achieve their specific capacitance potential. </div