Fabrication of high quality lead-free double perovskite Cs2AgBiBr6thin film and its application in memristor with ultralow operation voltage.

Recently, the lead-free double perovskite Cs2AgBiBr6has been considered as a promising candidate for next-generation nonvolatile memory and artificial synapse devices due to its high stability and low toxicity compared to its lead-based counterparts. In this work, we developed a simple and effective method to produce high-quality lead-free double perovskite Cs2AgBiBr6thin films without pinholes and particles by applying a low-pressure assisted method under ambient condition with a relative humidity (RH) of about 45%. The formation of pinholes and Ag precipitation in the perovskite Cs2AgBiBr6 films is effectively suppressed by the proper ratio of N,N-dimenthylformamide (DMF) mixed in dimethyl sulfoxide (DMSO) solvents. Furthermore, the grain size of the Cs2AgBiBr6films can be significantly increased by increasing the post-annealing temperature. Finally, a sandwiched structure memristor with an ITO/Cs2AgBiBr6/Ta configuration was successfully demonstrated, featuring ultralow operation voltage (VSet∼ 57 ± 23 mV,VReset∼ -692 ± 68 mV) and satisfactory memory window (the ratio ofRHRS/RLRS∼ 10 times), which makes it suitable for low-power consumption information storage devices.

Constructing Hollow Multishelled Microreactors with a Nanoconfined Microenvironment for Ofloxacin Degradation through Peroxymonosulfate Activation: Evolution of High-Valence Cobalt-Oxo Species.

This study constructed hollow multishelled microreactors with a nanoconfined microenvironment for degrading ofloxacin (OFX) through peroxymonosulfate (PMS) activation in Fenton-like advanced oxidation processes (AOPs), resulting in adequate contaminant mineralization. Among the microreactors, a triple-shelled Co-based hollow microsphere (TS-Co/HM) exhibited optimal performance; its OFX degradation rate was 0.598 min-1, which was higher than that of Co3O4 nanoparticles by 8.97-fold. The structural tuning of Co/HM promoted the formation of oxygen vacancies (VO), which then facilitated the evolution of high-valence cobalt-oxo (Co(IV)═O) and shifted the entire t2g orbital of the Co atom upward, promoting catalytic reactions. Co(IV)═O was identified using a phenylmethyl sulfoxide (PMSO) probe and in situ Raman spectroscopy, and theoretical calculations were conducted to identify the lower energy barrier for Co(IV)═O formation on the defect-rich catalyst. Furthermore, the TS-Co/HM catalyst exhibited remarkable stability in inorganic (Cl-, H2PO4-, and NO3-), organic (humic acid), real water samples (tap water, river water, and hospital water), and in a continuous flow system in a microreactor. The nanoconfined microenvironment could enrich reactants in the catalyst cavities, prolong the residence time of molecules, and increase the utilization efficiency of Co(IV)═O. This work describes an activation process involving Co(IV)═O for organic contaminants elimination. Our results may encourage the use of multishelled structures and inform the design of nanoconfined catalysts in AOPs.

Modulating the electron structure of Co-3d in Co3O4-x/WO2.72 for boosting peroxymonosulfate activation and degradation of sulfamerazine: Roles of high-valence W and rich oxygen vacancies.

Sulfate radical (SO4•-)-based heterogonous advanced oxidation processes (AOPs) show promising potential to degrade emerging contaminants, however, regulating the electron structure of a catalyst to promote its catalytic activity is challenging. Herein, a hybrid that consists of Co3O4-x nanocrystals decorated on urchin-like WO2.72 (Co3O4-x/WO2.72) with high-valence W and rich oxygen vacancies (OVs) used to modulate the electronic structure of Co-3d was prepared. The Co3O4-x/WO2.72 that developed exhibited high catalytic activity, activating peroxymonosulfate (PMS), and degrading sulfamerazine (SMR). With the use of Co3O4-x/WO2.72, 100 % degradation of SMR was achieved within 2 min, at a pH of 7, with the reaction rate constant k1 = 3.09 min-1. Both characterizations and density functional theory (DFT) calculations confirmed the formation of OVs and the promotion of catalytic activity. The introduction of WO2.72 greatly regulated the electronic structure of Co3O4-x. Specifically, the introduction of high-valence W enabled the Co-3d band centre to be closer to the Fermi level and enhanced electrons (e-) transfer ability, while the introduction of OVs-Co in Co3O4-x promoted the activity of electrons in the Co-3d orbital and the subsequent catalytic reaction. The reactive oxygen species (ROS) were identified as •OH, SO4•-, and singlet oxygen (1O2) by quenching experiments and electron spin resonance (EPR) analysis. The DFT calculation using the Fukui index indicated the reactive sites in SMR were available for an electrophilic attack, and three degradation pathways were proposed.

Interface Engineering of Co(OH)2 Nanosheets Growing on the KNbO3 Perovskite Based on Electronic Structure Modulation for Enhanced Peroxymonosulfate Activation.

Material-enhanced heterogonous peroxymonosulfate (PMS) activation on emerging organic pollutant degradation has attracted intensive attention, and a challenge is the electron transfer efficiency from material to PMS for radical production. Herein, an interface architecture of Co(OH)2 nanosheets growing on the KNbO3 perovskite [Co(OH)2/KNbO3] was developed, which showed high catalytic activity in PMS activation. A high reaction rate constant (k1) of 0.631 min-1 and complete removal of pazufloxacin within 5 min were achieved. X-ray photoelectron spectroscopy, X-ray absorption near edge structure spectra, and density functional theory (DFT) calculations revealed the successful construction of the material interface and modulated electronic structure for Co(OH)2/KNbO3, resulting in the hole accumulation on Co(OH)2 and electron accumulation on KNbO3. Bader topological analysis on charge density distribution further indicates that the occupations of Co-3d and O-2p orbitals in Co(OH)2/KNbO3 are pushed above the Fermi level to form antibonding states (σ*), leading to high chemisorption affinity to PMS. In addition, more reactive Co(II) with the closer d-band center to the Fermi level results in higher electron transfer efficiency and lower decomposition energy of PMS to SO4•-. Moreover, the reactive sites of pazufloxacin for SO4•- attack were precisely identified based on DFT calculation on the Fukui index. The pazufloxacin pathways proceeded as decarboxylation, nitroheterocyclic ring opening reaction, defluorination, and hydroxylation. This work can provide a potential route in developing advanced catalysts based on manipulation of the interface and electronic structure for enhanced Fenton-like reaction such as PMS activation.

Application of 3D hierarchical monoclinic-type structural Sb-doped WO3 towards NO2 gas detection at low temperature.

Currently, the development of semiconducting metal oxide (SMO)-based gas sensors with innovative modification and three-dimensional (3D) structural designs has become a significant scientific interest due to their potential for addressing key technological challenges. Herein, gas sensing devices based on the 3D hierarchical monoclinic-type structural Sb-doped WO3 (HMSW) gas sensing material were successfully constructed by ordered assembly of urchin-like monoclinic-type structural (P2/m) Sb-doped WO2.72 (W18O49) (UMSW) nanocrystals and nanowires. The crystalline microstructure, composition, morphological characteristics, and possible growth mechanisms were systematically investigated. The results of the gas sensor measurements, performed simultaneously on multiple samples, indicated that the 3D HMSW material has superior sensitivity (S = 122) and high selectivity to ppm-level NO2 at 30 °C with a significantly larger response than the best-reported values from other WO3-based gas sensors fabricated so far. All the results clearly demonstrate that the combined effects of abundant structural defects derived from Sb doping modification, reduced band gap, and 3D hierarchical microstructure synergistically play a key role in the NO2 gas sensing performance. Such excellent gas sensing performance foresees the great potential application of 3D hierarchical structural WO3-based sensors for fast and effective detection of toxic gases that can aid in human health and public safety.

Lipid profiling in sewage sludge.

High value-added reutilization of sewage sludge from wastewater treatment plants (WWTPs) is essential in sustainable development in WWTPs. However, despite the advantage of high value reutilization, this process must be based on a detailed study of organics in sludge. We used the methods employed in life sciences to determine the profile of lipids (cellular lipids, free fatty acids (FFAs), and wax/gum) in five sludge samples obtained from three typical WWTPs in Beijing; these samples include one sludge sample from a primary sedimentation tank, two activated sludge samples from two Anaerobic-Anoxic-Oxic (A2/O) tanks, and two activated sludge samples from two membrane bioreactor tanks. The percentage of total raw lipids varied from 2.90% to 12.3%. Sludge from the primary sedimentation tank showed the highest concentrations of lipid, FFA, and wax/gum and the second highest concentration of cellular lipids. All activated sludge contained an abundance of cellular lipids (>54%). Cells in sludge can from plants, animals, microbes and so on in wastewater. Approximately 14 species of cellular lipids were identified, including considerable high value-potential ceramide (9567-38774 mg/kg), coenzyme (937-3897 mg/kg), and some phosphatidylcholine (75-548 mg/kg). The presence of those lipid constituents would thus require a wider range of recovery methods for sludge. Both cellular lipids and FFAs contain an abundance of C16-C18 lipids at high saturation level, and they serve as good resources for biodiesel production.

Large-scale self-assembly of uniform submicron silver sulfide material driven by precise pressure control.

The controllable self-assembly of nanosized building blocks into larger specific structures can provide an efficient method of synthesizing novel materials with excellent properties. The self-assembly of nanocrystals by assisted means is becoming an extremely active area of research, because it provides a method of producing large-scale advanced functional materials with potential applications in the areas of energy, electronics, optics, and biologics. In this study, we applied an efficient strategy, namely, the use of 'pressure control' to the assembly of silver sulfide (Ag2S) nanospheres  with a diameter of approximately 33 nm into large-scale, uniform Ag2S sub-microspheres with a size of about 0.33 µm. More importantly, this strategy realizes the online control of the overall reaction system, including the pressure, reaction time, and temperature, and could also be used to easily fabricate other functional materials on an industrial scale. Moreover, the thermodynamics and kinetics parameters for the thermal decomposition of silver diethyldithiocarbamate (Ag(DDTC)) are also investigated to explore the formation mechanism of the Ag2S nanosized building blocks which can be assembled into uniform sub-micron scale architecture. As a method of producing sub-micron Ag2S particles by means of the pressure-controlled self-assembly of nanoparticles, we foresee this strategy being an efficient and universally applicable option for constructing other new building blocks and assembling novel and large functional micromaterials on an industrial scale.

Comparison of biodiesel production from sewage sludge obtained from the A²/O and MBR processes by in situ transesterification.

The potential of two types of sludge obtained from the anaerobic-anoxic-oxic (A(2)/O) and membrane bioreactor (MBR) processes as lipid feedstock for biodiesel production via in situ transesterification was investigated. Experiments were conducted to determine the optimum conditions for biodiesel yield using three-factor and four-level orthogonal and single-factor tests. Several factors, namely, methanol-to-sludge mass ratio, acid concentration, and temperature, were examined. The optimum yield of biodiesel (16.6% with a fatty acid methyl ester purity of 96.7%) from A(2)/O sludge was obtained at a methanol-to-sludge mass ratio of 10:1, a temperature of 60°C, and a H2SO4 concentration of 5% (v/v). Meanwhile, the optimum yield of biodiesel (4.2% with a fatty acid methyl ester purity of 92.7%) from MBR sludge was obtained at a methanol-to-sludge mass ratio of 8:1, a temperature of 50°C, and a H2SO4 concentration of 5% (v/v). In this research, A(2)/O technology with a primary sedimentation tank is more favorable for obtaining energy from wastewater than MBR technology.

Binary Synergy Strengthening and Toughening of Bio-Inspired Nacre-like Graphene Oxide/Sodium Alginate Composite Paper.

A crucial requirement for most engineering materials is the excellent balance of strength and toughness. By mimicking the hybrid hierarchical structure in nacre, a kind of nacre-like paper based on binary hybrid graphene oxide (GO)/sodium alginate (SA) building blocks has been successfully fabricated. Systematic evaluation for the mechanical property in different (dry/wet) environment/after thermal annealing shows a perfect combination of high strength and toughness. Both of the parameters are nearly many-times higher than those of similar materials because of the synergistic strengthening/toughening enhancement from the binary GO/SA hybrids. The successful fabrication route offers an excellent approach to design advanced strong integrated nacre-like composite materials, which can be applied in tissue engineering, protection, aerospace, and permeable membranes for separation and delivery.

A High-Rate and Ultralong-Life Sodium-Ion Battery Based on NaTi2 (PO4 )3 Nanocubes with Synergistic Coating of Carbon and Rutile TiO2.

Highly regular NaTi2 (PO4 )3 nanocubes with synergistic nanocoatings of rutile TiO2 and carbon are prepared as an electrode material for sodium-ion batteries. It exhibits a high rate and ultralong life performance simultaneously, and a capacity retention of 89.3% after 10 000 cycles is achieved.

Facile, one-pot synthesis, and antibacterial activity of mesoporous silica nanoparticles decorated with well-dispersed silver nanoparticles.

In this study, we exploit a facile, one-pot method to prepare MCM-41 type mesoporous silica nanoparticles decorated with silver nanoparticles (Ag-MSNs). Silver nanoparticles with diameter of 2-10 nm are highly dispersed in the framework of mesoporous silica nanoparticles. These Ag-MSNs possess an enhanced antibacterial effect against both Gram-positive and Gram-negative bacteria by preventing the aggregation of silver nanoparticles and continuously releasing silver ions for one month. The cytotoxicity assay indicates that the effective antibacterial concentration of Ag-MSNs shows little effect on human cells. This report describes an efficient and economical route to synthesize mesoporous silica nanoparticles with uniform silver nanoparticles, and these nanoparticles show promising applications as antibiotics.

Effect of mesoporous silica nanoparticles on dentinal tubule occlusion: an in vitro study using SEM and image analysis.

The occlusion of dentinal tubules is considered to be an effective strategy to treat dentin hypersensitivity. This in vitro study introduced mesoporous silica nanoparticles (MSNs) for tubular occlusion to achieve deeper sealing. Further, MSNs with independently encapsulated calcium and phosphates (as calcium and phosphate sources) (Ca(2+)/PO4(3-)@MSNs) were introduced to achieve improved efficacy of tubular occlusion and remineralization. MSNs or Ca(2+)/PO4(3-)@MSNs were proportionally mixed with distilled water to make their respective desensitizing slurries, which were used to treat dentin surfaces. The efficacy of tubular occlusion was evaluated using scanning electron microscopy (SEM) images and an image analyzer, and compared with that achieved with Green-Or -a commonly used densitizer. The results demonstrated that both MSNs and Ca(2+)/PO4(3-)@MSNs almost completely occluded dentinal tubules and formed a deeper seal which penetrated about 105 µm deep into the dentinal tubules. Significant differences in tubular occlusion were observed between Green-Or densitizer and MSNs or Ca(2+)/PO4(3-)@MSNs. The novel MSNs-based nanomaterials showed great potential as a treatment option for dentin hypersensitivity.

Development and validation of a highly sensitive LC-ESI-MS/MS method for the determination of hyperoside in beagle dog plasma: application to a pharmacokinetic study.

A highly sensitive, rapid assay method has been developed and validated for the analysis of hyperoside in beagle dog plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive-ion mode. The assay procedure involves extraction of hyperoside and ginsenoside Re (IS) from beagle dog plasma. Chromatographic separation was carried out on an Agilent Zorbax XDB-C18 (100 × 2.1 mm, 1.8 µm) column by isocratic elution with acetonitrile and water (50:50, v/v) at a flow rate of 0.25 mL/min with a total run time of 2.0 min. The MS/MS ion transitions monitored were 464.4 → 463.4 for hyperoside and 947.12 → 969.60 for IS. Linear responses were obtained for hyperoside ranging from 10 to 5000 ng/mL. The intra-and inter-day precisions (RSDs) were <5.38 and 3.39% and the extraction recovery ranged from 94.39 to 100.78% with an RSD <3.82%. Stability studies showed that hyperoside was stable in preparation and analytical process. The results indicated that the validated method was successfully used to determine the concentration-time profiles of hyperoside.

[Study on applicability of kinetic model for water extracts from puerariae radix].

To establish an appropriate experimental and data processing method on the basis of the general kinetic model for extraction of traditional Chinese medicines, in order to study the effect of total flavonoids in water extracts from Puerariae Radix on the adaptability of the model, with total flavonoids of Puerariae Radix as the determination indicator. The results showed that the natural logarithm of mass concentration of total flavonoids showed a good linearity with the changes in extraction time and solvent volume. Through calculating and fitting, we successfully established the kinetic model for water extraction of total flavonoids from Puerariae Radix, and verified its accuracy. Its good fitting degree and controllable deviation within the range of industrial production requirements indicated a good adaptability of the model. However, its equation correction factors require further studies.

Regulation of CFTR trafficking by its R domain.

Phosphorylation of the R domain is required for cystic fibrosis transmembrane conductance regulator (CFTR) channel gating, and cAMP/protein kinase A (PKA) simulation can also elicit insertion of CFTR into the plasma membrane from intracellular compartments (Bertrand, C. A., and Frizzell, R. A. (2003) Am. J. Physiol. 285, C1-C18). We evaluated the structural basis of regulated CFTR trafficking by determining agonist-evoked increases in plasma membrane capacitance (Cm) of Xenopus oocytes expressing CFTR deletion mutants. Expression of CFTR as a split construct that omitted the R domain (Deltaamino acids 635-834) produced a channel with elevated basal current (Im) and no DeltaIm or trafficking response (DeltaCm) upon cAMP/PKA stimulation, indicating that the structure(s) required for regulated CFTR trafficking are contained within the R domain. Additional deletions showed that removal of amino acids 817-838, a 22-amino acid conserved helical region having a net charge of -9, termed NEG2 (Xie, J., Adams, L. M., Zhao, J., Gerken, T. A., Davis, P. B., and Ma, J. (2002) J. Biol. Chem. 277, 23019-23027), produced a channel with regulated gating that lacked the agonist-induced increase in CFTR trafficking. Injection of NEG2 peptides into oocytes expressing split DeltaNEG2 CFTR prior to stimulation restored the agonist-evoked DeltaCm, consistent with the concept that this sequence mediates the regulated trafficking event. In support of this idea, DeltaNEG2 CFTR escaped from the inhibition of wild type CFTR trafficking produced by overexpression of syntaxin 1A. These observations suggest that the NEG2 region at the C terminus of the R domain allows stabilization of CFTR in a regulated intracellular compartment from which it traffics to the plasma membrane in response to cAMP/PKA stimulation.