Additional file 1: of Chinese herbal bath therapy for the treatment of uremic pruritus: meta-analysis of randomized controlled trials

Links of the 17 included articles. (DOCX 21 kb

New Insights into Nano Magnetite Enhancing Anaerobic Digestion: Regulating the Intracellular Electron Bifurcation and Storing Energy for Methanogens to Respond to Unfavorable Conditions

Nano magnetite has been reported to enhance the syntrophic metabolism of anaerobic digestion by serving as an electron bridge between microorganisms. However, the underlying mechanism is not fully understood. We hypothesized that nano magnetite might regulate intracellular electron bifurcation to drive the reduction of ferredoxin (E = −500 mV) via a thermodynamically favorable reaction to store energy that makes anaerobic systems more effective. Results of this study show that the addition of nano magnetite to an anaerobic digester improved methane production under the high influent COD concentration. Metagenomic analysis revealed that the abundance of subunits of the electron bifurcation enzymes MvhADG-HdrABC and HdrA2B2C2 was higher than that without nano magnetite. Metaproteomic tests showed that the contents of HS–CoM and HS–CoB associated with electron bifurcation during methanogenesis increased by 30.2% and ferredoxin increased by 156.5% with the addition of nano magnetite. As a result, the ATP production was indirectly driven by the electron bifurcation increase by 41.2%, and the total abundance of hydrogenotrophic methanogens containing MvhADG-HdrABC and aceticlastic methanogens containing HdrA2B2C2 also increased. These findings suggest that nano magnetite might improve intracellular electron bifurcation to methanogens to respond to load shock by storing energy

Regulating Secretion of Extracellular Polymeric Substances through Dosing Magnetite and Zerovalent Iron Nanoparticles To Affect Anaerobic Digestion Mode

Anaerobic digestion technology is a promising method to reduce the usage of fossil fuels by transforming organic waste into biogas. Nano zerovalent iron (nZVI) and nano iron oxide have been reported to affect metabolism modes of anaerobic digestion, i.e., interspecies hydrogen transfer (IHT) and direct interspecies electron transfer (DIET). However, the effects of the nanoparticles on extracellular polymeric substance (EPS) potentially capable of participating in the mass transfer or electron transfer of these two metabolism modes remains unclear. In this study, the addition of nanomagnetite (nFe3O4) significantly enhanced the performance of anaerobic treatment, while adding nZVI led to a decline of the performance. nFe3O4 stimulated the secretion of proteins and humic substances in EPS, which were confirmed electroactive to serve as electron shuttles to enhance the DIET pathway of anaerobic digestion. In contrast, the addition of nZVI increased EPS especially polysaccharide to resist cell disruption caused by nZVI, which resulted in an inefficient mass transfer to decrease IHT. These results were in agreement with the microbial community analysis and the functional gene prediction

Establishment of an Electroactive Microorganism Community in Anaerobic Digestion with Photosynthetic Bacteria Agents for Promoting Methane Production

Efficient electron transfer among anaerobes is critical to maintaining the high performance of anaerobic digestion. In this study, photosynthetic bacteria (PSB), as exoelectrogenic bacteria, were added to a light anaerobic digester to establish the electroactive microorganism community for the improvement of methane production during anaerobic digestion. Results showed that the daily methane production increased by 37% and the chemical oxygen demand (COD) removal efficiency increased from 70% to over 90%, accompanied by the increase of F420, ATP, and NADH/NAD+ of the sludge. The electrochemical activity of the anaerobic sludge such as capacitance and conductance increased by 28 and 16%, respectively, and the extracellular electron transfer capacity of the sludge nearly doubled. In addition, the PSB agents promoted the secretion of conductive proteins and EPS, such as the OmcS copy number increasing more than 100 times, which provided a bridge for electron transfer between other microorganisms in the sludge. Correspondingly, PSB promoted the enrichment of electrotrophic methanogens, Methanosarcina, whose abundance increased from 0.76 to 34.7%. Also, it increased the proliferation of other exoelectrogenic bacteria such as Syntrophomonas. In brief, a mutually beneficial electroactive community was established by the addition of PSB agents to facilitate electron transfer for methane production during anaerobic digestion

Structure Defect Tuning of Metal–Organic Frameworks as a Nanozyme Regulatory Strategy for Selective Online Electrochemical Analysis of Uric Acid

Nanozymes have been designed to address the limitations of high cost and poor stability involving natural enzymes in analytical applications. However, the catalytic efficiency of the nanozyme still needs to be improved so that it can meet the selectivity and stability requirements of accurate biomolecule analysis. Here, we presented structure defects of metal–organic frameworks (MOFs) as a tuning strategy to regulate the catalytic efficiency of artificial nanozymes and investigated the roles of defects on the catalytic activity of oxidase-like MOFs. Structural defects were introduced into a novel Co-containing zeolitic imidazolate framework with gradually loosened morphology (ZIF-L-Co) by doping cysteine (Cys). It was found that with the increase in defect degree, the properties of materials such as ascorbate oxidase-like, glutathione oxidase-like, and laccase-like were obviously enhanced by over 5, 2, and 3 times, respectively. In-depth structural investigations indicate that the doping of sulfur inducing structural defects which may destroy the equilibrium state between cobalt and nitrogen in 2-methylimidazole and distort the crystal lattice, thereby enhancing the adsorption of oxygen and thus promoting the oxidase-like activity. The ZIF-L-Co-10 mg with enhanced ascorbate oxidase- and laccase-like activity was loaded into a microreactor and integrated into an online electrochemical system (OECS) in the upstream of the detector. This nanozyme-based microreactor can completely remove ascorbic acid, dopamine, and 3,4-dihydroxyphenylacetic acid which are the main interference toward uric acid (UA) electrochemical measurement, and the ZIF-L-Co-10 mg Cys-based OECS system is capable of continuously capturing UA change in rat brain following ischemia–reperfusion injury. Structure defect tuning of ZIF-L-Co not only provides a new regulatory strategy for artificial nanozyme activity but also provides a critical chemical platform for the investigation of UA-related brain function and brain diseases

Synthesis of Trisubstituted Furans via Copper(I)-Catalyzed Strain-Driving Cycloisomerization/Annulative Fragmentation

The in situ formed furan-fused cyclobutenes via Cu­(I)-catalyzed cycloisomerization of readily available allenyl ketones bearing a cyclopropyl moiety are a highly reactive and powerful species, which undergo annulative fragmentation with terminal ynones to afford a wide variety of functional furans in moderate to high yields. This ring-distortion protocol features an unprecedented strain-controlled cycloisomerization/Diels–Alder/retro-Diels–Alder (CDRD) sequence under mild conditions

Amorphous Fe–Mo–O Nanostructures for Catalytic Water Oxidation

Promoting the development of highly efficient and long-term stable oxygen evolution reaction (OER) electrocatalysts is crucial to relieve the energy crisis. In this study, amorphous Fe–Mo–O/NF was designed as an effective and durable catalyst for OER in 1.0 M KOH aqueous solution. The OER catalytic performance of amorphous Fe–Mo–O/NF is obviously improved compared to Fe2O3/NF. The synthesized amorphous Fe–Mo–O/NF exhibits excellent catalytic activity and the current density reached 50 and 100 mA cm–2 in 1.0 M KOH aqueous solution with only overpotentials of 215 and 224 mV. This remarkable electrocatalytic activity is considered as the following: (1) The pristine catalytic performance originates from the OER catalytic activity inherent in transition-metal Fe-based oxides electrocatalysts; (2) the introduction of Mo element increases the number of active sites; (3) the coupling synergy effect between metals is more conducive to the adsorption of oxygen intermediates; and (4) the tight bonding of the amorphous Fe–Mo–O nanostructures to the conductive substrate ensures the structure rapid electron transport and ultrahigh stability. We anticipate that our research will extend the range of transition-metal-based materials as effective electrocatalysts for OER

Metal–Organic Framework-Coated Fiber Network Enabling Continuous Ion Transport in Solid Lithium Metal Batteries

Poly­(ethylene oxide) (PEO)-based solid-state polymer electrolytes (SPEs) have limited application in lithium metal batteries due to their low room-temperature ionic conductivity and high interfacial impedance with electrodes. Constructing efficient enhancers is a promising way to tackle these critical issues, but still remains a huge challenge. In this study, a continuous and hierarchical lithium-ion transport network was constructed by growing a copper-based metal–organic framework (MOF) (Cu–MOF-74) on a three-dimensional (3D) nonwoven fabric (NWF). The incorporation of the high-surface-area NWF effectively prevents MOF particle agglomeration, thereby creating a 3D interconnected network of ion transportation channels that span both vertically and laterally. Additionally, MOF nanoparticles with functional groups exhibit a high affinity toward bis­(tri-fluoromethanesulfonyl) imide anions, which is facilitated by hydrogen bonding between oxygen-containing functional groups and fluorine, as well as metal–oxygen bonds, releasing more free lithium ions. The as-prepared electrolyte exhibits a fast ionic conductivity of 1.0 × 10–4 S cm–1 at 30 °C, a high lithium-ion transference number of 0.39, and a wide electrochemical window of 4.9 V. The all-solid-state Li–LiFePO4 cells possess a high initial discharge capacity of 160.4 mAh g–1 at 0.5C, excellent rate performance (specific capacity reached 148.6 mAh g–1 at 2.0C), and good cycle stability. This approach presents a cost-effective and efficient strategy for enhancing PEO-based SPEs, providing a promising direction for overcoming the challenge of low ionic conductivity in all-solid-state lithium metal batteries

Tunable Gold(I)-Catalyzed [4 + 3] Cycloaddition for Divergent Synthesis of Furan-Fused N,O-Heterocycles

By choosing suitable ligand-directed gold catalysts, two types of gold-containing all-carbon 1,4-dipoles could be generated selectively from the gold­(I)-catalyzed cycloisomerizations of allenyl ketones bearing a cyclopropyl moiety, which undergo [4 + 3] cycloadditions with nitrones to produce two regiomers of furan-condensed N,O-seven-membered rings in moderate to excellent yields highly selectively

Bioinspired CuZn-N/C Single-Atom Nanozyme with High Substrate Specificity for Selective Online Monitoring of Epinephrine in Living Brain

Though many elegant laccase mimics have emerged, these mimics generally have no substrate selectivity as well as low activity, making it difficult to fulfill the demand for monitoring in physiological conditions. Herein, inspired by the Cu–N ligand structure in the active site of natural laccase, we revealed that a carbon nanomaterial with atomically dispersed Cu and Zn atoms (CuZn-N/C) and a well-defined ligand structure could function as an effective laccase mimic for selectively catalyzing epinephrine (EP) oxidation. Catalytic activity of the CuZn-N/C nanozyme was superior to those of Cu–N/C and Zn–N/C and featured a Km value nearly 3-fold lower than that of natural laccase, which indicated that CuZn-N/C has a better affinity for EP. Density functional theory (DFT) revealed the mechanism of the superior catalytic ability of dual-metal CuZn-N/C as follows: (1) the exact distance of the two metal atoms in the CuZn-N/C catalyst makes it suitable for adsorption of the EP molecule, and the CuZn-N/C catalyst can offer the second hydrogen bond that stabilizes the adsorption; (2) molecular orbitals and density of states indicate that the strong interaction between the EP molecule and CuZn-N/C is important for EP catalytic oxidization. Furthermore, a sensitive and selective online optical detection platform (OODP) is constructed for determining EP with a low limit of detection (LOD) of 0.235 μM and a linear range of 0.2–20 μM. The system allows real-time measurement of EP release in the rat brain in vivo following ischemia with dexmedetomidine administration. This work not only provides an idea of designing efficient laccase mimics but also builds a promising chemical platform for better understanding EP-related drug action for ischemic cerebrovascular illnesses and opens up possibilities to explore brain function