Surface Modification of Polyimide Aerogel by Thermoplastic Polyurethane for Enhanced Mechanical Strength and Thermal Insulation Performance.

Polyimide (PI) aerogel is a good thermal insulation material with the highest temperature resistance in practical application. But the mechanical strength of PI aerogels prepared by freeze-drying or thermoimide methods is weak. In this research, TPU was selected as an aging solution to solve the problem of the low mechanical strength of PI aerogel prepared by the freeze-drying method. Previous work has certified that the coupling of PI and thermoplastic polyurethane (TPU) can enhance the mechanical strength of PI aerogel to a certain extent due to the flexibility of TPU. But excessive TPU will change the PI structure in the cross-linking process and decrease the mechanical strength of the aerogel. Thus, a new kind of PI gel modification method was provided by using TPU as an aging solution, and the mechanical strength of PI aerogel is improved to 3.06 MPa. Furthermore, the shrinkage, specific surface area, waterproof angle, and thermal conductivity all show good performance, thus enabling PI aerogel to be used in many aspects. Specially, the method is simple and can be used to prepare some other high-strength aerogels.

The role of iron-rich hydrosaline liquids in the formation of Kiruna-type iron oxide-apatite deposits.

Kiruna-type iron oxide-apatite (IOA) deposits, an important source of iron, show close associations with andesitic subvolcanic intrusions. However, the processes of ore formation and the mechanism controlling iron concentration remain uncertain. Here, we report the widespread presence of high-temperature (>800°C) water-poor multisolid hydrosaline liquid inclusions in pre- and syn-ore minerals from IOA deposits of eastern China. These inclusions consistently homogenize to a liquid phase by vapor disappearance and mostly contain 3 to 10 wt % Fe, signifying a substantial capacity for iron transportation by such hydrosaline liquids. We propose that the hydrosaline liquids were likely immiscible from the dioritic magmas with high Cl/H2O in subvolcanic settings. Subsequent reaction with host rocks and/or decompression and cooling of the hydrosaline liquids is deemed responsible for the simultaneous formation of high-temperature alteration and magnetite ores, thereby providing important insights into the distinctive characteristics of IOA deposits in shallow magmatic-hydrothermal systems.

Carboxymethyl cellulose/polyvinyl alcohol composite aerogel supported beta molecular sieve for CH4 adsorption and storage.

Biomass aerogel is attractive in various applications due to their renewable, biodegradable and eco-friendly advantages. Herein, a novel beta molecular sieve/carboxymethyl cellulose/polyvinyl alcohol composite aerogel (beta/CP) is prepared by direct mixing and directional freeze-drying as an efficient gas adsorbent with hierarchical porosity. The beta molecular sieve is uniformly dispersed in the three-dimensional skeleton of the aerogel. By adjusting the loading mass of the beta molecular sieve to constitute a reasonable porosity and pore size distribution, the synergistic effect between pore structures of different scales improves the adsorption performance. The experiment results of beta/CP-4 show that the CH4 adsorption capacity can reach 60.33 cm3/g at 298 K and 100 bar, which is almost the same as that of the pure beta molecular sieve (62.09 cm3/g). The strong interaction between the aerogel and it prevents the molecular sieve agglomeration, improves the pore utilization, and also reduces the cost of using molecular sieve adsorbent. The above results indicate that the composite has good potential for application in the field of CH4 storage.

A multifunctional PAN/PVP nanofiber sponge wound dressing loaded with ZIF-8-derived carbon nanoparticles with adjustable wetness for rapid wound disinfection and exudate management.

Rapid and safe disinfection and exudate management are two major challenges in infected wound care. Therefore, in this work, we developed a novel wound dressing via encapsulating ZIF-8-derived carbon nanoparticles in a hydrophilic nanofiber sponge to address severe wound infection and heavy exudate problems. The dressing can effectively kill bacteria through chemo-photothermal synergistic therapy. Meanwhile, the hydrophilic nanofiber sponge can quickly absorb wound exudate around the wound and accelerate the evaporation rate of liquid through the photothermal effect and its own structure; therefore, it is possible to remove excess liquid and regulate its wetness. In this way, it prevents the problem of wound overhydration often caused by hydrophilic dressings. In our experiment, the dressing showed good antibacterial performance and biocompatibility in vitro and could effectively control wound infection, absorb wound exudate and promote skin wound healing in vivo. Its good therapeutic effect is not only due to effective infection control and wound exudate management, but also because the structure of nanofibers similar to an extracellular matrix provides basic physical support and structural  signals conducive to skin tissue regeneration.

Fabrication and Characterization of a High-Strength Polyimide/Thermoplastic Polyurethane Composite Aerogel with Hydrophobicity and Low Thermal Conductivity.

Polyimide (PI) aerogel has surfaced in research and development as a result of its heat resistance, flame retardancy, and low dielectric constant. However, it is still a challenge to reduce the thermal conductivity while improving its mechanical strength and retaining hydrophobicity. Herein, the PI/thermoplastic polyurethane (TPU) composite aerogel was synthesized by coupling TPU with PI via a novel method of chemical imidization combined with freeze-drying technology. With this technique, PI aerogel with excellent comprehensive performance is produced. Interestingly, the volume shrinkage of the composite aerogel decreased from 24.14 to 5.47%, which leads to low density (0.095 g/cm3) and elevated porosity (92.4%). In addition, strong mechanical strength (1.29 MPa) and high hydrophobicity (123.6°) were achieved. More importantly, PI/TPU composite aerogel demonstrated a low thermal conductivity of 29.51 mW m-1 K-1 at ambient temperature. Therefore, PI/TPU composite aerogel can be a promising material for hydrophobic and thermal insulation applications.

Sodium Alginate-Based Carbon Aerogel-Supported ZIF-8-Derived Porous Carbon as an Effective Adsorbent for Methane Gas.

Adsorption natural gas (ANG) is a technology in which natural gas is stored on the surface of porous materials at relatively low pressures, which are promising candidates for adsorption of natural gas. Adsorbent materials with a large surface area and porous structure plays a significant role in the ANG technology, which holds promise in increasing the storage density for natural gas while decreasing the operating pressure. Here, we demonstrate a facile synthetic method for rational construction of a sodium alginate (SA)/ZIF-8 composite carbon aerogel (AZSCA) by incorporating ZIF-8 particles into SA aerogel through a directional freeze-drying method followed by the carbonization process. The structure characterization shows that AZSCA has a hierarchical porous structure, in which the micropores originated from MOF while the mesopores are derived from the three-dimensional network of the aerogel. The experimental results show that AZSCA achieved high methane adsorption of 181 cm3·g-1 at 65 bar and 298 K, along with higher isosteric heat of adsorption (Qst) throughout the adsorption range. Thus, the combination of MOF powders with aerogel can find potential applications in other gas adsorption.

Abnormal regional homogeneity in right caudate as a potential neuroimaging biomarker for mild cognitive impairment: A resting-state fMRI study and support vector machine analysis.

Objective: Mild cognitive impairment (MCI) is a heterogeneous syndrome characterized by cognitive impairment on neurocognitive tests but accompanied by relatively intact daily activities. Due to high variation and no objective methods for diagnosing and treating MCI, guidance on neuroimaging is needed. The study has explored the neuroimaging biomarkers using the support vector machine (SVM) method to predict MCI. Methods: In total, 53 patients with MCI and 68 healthy controls were involved in scanning resting-state functional magnetic resonance imaging (rs-fMRI). Neurocognitive testing and Structured Clinical Interview, such as Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) test, Activity of Daily Living (ADL) Scale, Hachinski Ischemic Score (HIS), Clinical Dementia Rating (CDR), Montreal Cognitive Assessment (MoCA), and Hamilton Rating Scale for Depression (HRSD), were utilized to assess participants' cognitive state. Neuroimaging data were analyzed with the regional homogeneity (ReHo) and SVM methods. Results: Compared with healthy comparisons (HCs), ReHo of patients with MCI was decreased in the right caudate. In addition, the SVM classification achieved an overall accuracy of 68.6%, sensitivity of 62.26%, and specificity of 58.82%. Conclusion: The results suggest that abnormal neural activity in the right cerebrum may play a vital role in the pathophysiological process of MCI. Moreover, the ReHo in the right caudate may serve as a neuroimaging biomarker for MCI, which can provide objective guidance on diagnosing and managing MCI in the future.

A single dual-targeting fluorescent probe enables exploration of the correlation between the plasma membrane and lysosomes.

The interactions between organelles can maintain normal cell activity. Lysosomes, as waste disposal systems of cells, have many important interactions with the plasma membrane, especially in the repair of cracked plasma membrane. Unfortunately, a way to study the relationship between them synchronously is still lacking. Therefore, in this work, we constructed a dual-targeting probe (Mem-Lyso) to simultaneously visualize the plasma membrane and lysosomes for the first time. Taking advantage of dual-targeting, the probe Mem-Lyso could successfully track and analyze the dynamic changes of the plasma membrane and lysosomes in different bioprocesses. The experimental results demonstrated that, compared to the normal status, there was obvious fusion between the plasma membrane and lysosomes in the apoptosis process. Furthermore, because of the sensitivity to polarity, Mem-Lyso could label the plasma membrane and lysosomes with red and yellow colors in cells, respectively. Moreover, the skeleton and gastrointestinal wall of zebrafish were visualized by dual-color imaging, respectively. More importantly, the dual-targeting property endowed Mem-Lyso with the ability to spatially distinguish the cholesterol (CL) content in the plasma membrane, which provided a potential detection tool for biological research and diagnosis of related diseases.

Preparation and Properties of the Urea-Formaldehyde Res-In/Reactive Halloysite Nanocomposites Adhesive with Low-Formaldehyde Emission and Good Water Resistance.

Low-cost urea formaldehyde resin (UF)/reactive halloysite nanotubes (HNTs) nanocomposite adhesive was prepared successfully via in situ polymerization. The HNTs were modified to improve its compatibility with polymer. The XRD and FTIR results showed that physical and chemical interaction between the HNTs and polymer resin influenced the structure of UF owing to the functional groups on the HNTs. It is found from SEM images that the modified HNTs could be dispersed uniformly in the resin and the nanocomposite particles were spherical. The performance experiment confirmed that thermal stability of nanocomposite increased largely, formaldehyde emission of UF wood adhesive reduced 62%, and water resistance of UF wood adhesive improved by 84%. Meanwhile, the content of HNTs on the nanocomposites could be up to 60 wt %. The mechanism of the nanocomposites based on the reactive HNTs was proposed. The approach of the preparation could supply an idea to prepare other polymer/clay nanocomposites.

Z-scheme polyimide/tungsten trioxide aerogel photocatalyst for enhanced photocatalytic CO2reduction under visible light.

Developing highly efficient and stable photocatalysts is an effective method to achieve CO2photocatalytic reduction. Herein, PI/WO3aerogel photocatalyst was prepared by chemical amide reaction coupled with an ethanol supercritical drying technique. The novel aerogel photocatalysts exhibit excellent photocatalytic performance for reducing CO2into CO. In particular, PI/WO3-10 aerogel photocatalyst shows the highest yield of CO (5.72µmol g-1h-1), which is ca 11-fold higher than that of the pristine PI aerogel. The high CO2reduction activity can be attributed to the Z-scheme structure, which enhances the separation of photo-generated electron-holes, and induces H2O oxidation on WO3nanosheets and CO2reduction on PI aerogel. The photocatalytic reaction mechanism of CO2when using PI/WO3aerogel photocatalyst is proposed.

Nitrogen-doped carbon composite derived from ZIF-8/polyaniline@cellulose-derived carbon aerogel for high-performance symmetric supercapacitors.

Cellulose derived carbon aerogel (CA) with unique three-dimensional network coated with polyaniline (PANI) on its surface is used as a scaffolding framework to anchor ZIF-8. The designed ZIF-8 derived porous carbon (ZC)/PANI@CA (ZPCA) hybrid carbon composite through a facile solution immersion chemical route and subsequent carbonization process is employed as electrode for supercapacitor, which has contributed a large specific surface area, a hierarchical porous structure and reasonable N content (up to 6.27 at.%). The synthesized ZPCA electrode achieves an outstanding capacitance of 388 F g-1 at 0.5 A g-1 as well as an excellent cycling performance. More inspiringly, the symmetric supercapacitor based ZPCA achieves a high energy density of 13.4 Wh kg-1 at a power density of 250 W kg-1 using 2 M KOH aqueous solution, and an ultrahigh energy density of 81.8 Wh kg-1 at a power density of 950 W kg-1 is realized using Et4NBF4/AN electrolyte.

High-performance asymmetric supercapacitor made of NiMoO4 nanorods@Co3O4 on a cellulose-based carbon aerogel.

In this study, a new nanoporous material comprising NiMoO4 nanorods and Co3O4 nanoparticles derived from ZIF-67 supported by a cellulose-based carbon aerogel (CA) has been successfully synthesized using a two-step hydrothermal method. Due to its chemical composition, the large specific surface and the hierarchical porous structure, the NiMoO4@Co3O4/CA ternary composite yields electrodes with an enhanced specific capacitance of 436.9 C/g at a current density of 0.5 A/g and an excellent rate capability of 70.7% capacitance retention at 5.0 A/g. Moreover, an advanced asymmetric supercapacitor (ASC) is assembled using the NiMoO4@Co3O4/CA ternary composite as the positive electrode and activated carbon as the negative electrode. The ASC device exhibits a large capacitance of 125.4 F/g at 0.5 A/g, a maximum energy density of 34.1 Wh/kg at a power density of 208.8 W/kg as well as a good cyclic stability (84% after 2000 cycles), indicating its wide applicability in energy storage. Finally, our results provide a general approach to the construction of CA and MOF-based composite materials with hierarchical porous structure for potential applications in supercapacitors.

Highly efficient visible-light-induced photoactivity of carbonized polyimide aerogel for antibiotic degradation.

Various nitrogen (N)-doped carbon materials have been designed as efficient photocatalysts. For the first time, polyimide (PI) aerogels were calcined to be N-doped carbon photocatalysts at different temperatures. The structures of the carbonized polyimide aerogels (CPIs) vary with the carbonization temperature. The conductivity of the CPI increases with the improvement of calcination temperature, whereas the N content of the CPI decreases and the N state also changes. Thus, the electronic properties of the CPI are changed. The photocatalytic experiments certified that the PI aerogel calcined at 800 °C exhibited the highest photocatalytic performance. The chlortetracycline (CTC) degradation rate over CPI-800 aerogel is 2.3 times as much as that of PI aerogel due to the changed structure and properties of the CPI-800 aerogel.

Ce3+ self-doped CeOx/FeOCl: an efficient Fenton catalyst for phenol degradation under mild conditions.

Herein, a novel Ce3+ self-doped CeOx/FeOCl composite was successfully prepared by a facile method for the first time, which showed remarkable catalytic activity as a Fenton catalyst in the degradation of phenol under the conditions of a neutral solution, room temperature and natural light. In CeOx/FeOCl, 5.23% CeOx is the optimal condition, and the degradation constant (k) of CeOx/FeOCl is greater than that of FeOCl by a factor of 10.8. CeOCl in the composite plays a more important role than CeO2, which greatly increases the production of ˙OH radicals. Furthermore, the Ce-doping in FeOCl accelerates the separation efficiency of the photogenerated electron-hole pairs. The increased surface area and surface potential of CeOx/FeOCl than those of FeOCl effectively promote the adsorption of phenol, which is 4.05 times that of FeOCl. According to the DFT calculations, the Ce-doping in FeOCl enhances the structural stability by increasing the strength of the chemical bonds. The adsorption of H2O2 with Ce3+ is energetically favorable, which promotes the production of ˙OH radicals. A synergistic mechanism for the enhanced catalytic performance of CeOx/FeOCl is proposed.

A Z-Scheme Polyimide/AgBr@Ag Aerogel with Excellent Photocatalytic Performance for the Degradation of Oxytetracycline.

A novel Z-scheme polyimide (PI)/AgBr@Ag aerogel photocatalyst has been successfully synthesized by combining an in situ precipitation method and a supercritical drying method. The as-prepared PI/AgBr@Ag-50 (50 wt % AgBr@Ag in PI/AgBr@Ag) aerogel photocatalyst exhibited excellent photocatalytic activity for oxytetracycline degradation with a rate constant of 0.025 min-1 , which was 6.9 and 2.6 times higher than that of the PI aerogel or the AgBr@Ag nanoparticles, respectively. More significantly, the PI/AgBr@Ag-50 aerogel photocatalyst showed stable cycling, which could be attributed to the high mechanical strength and 3D network of the PI aerogel. The introduction of AgBr@Ag on PI with a heterojunction structure efficiently promoted the separation of electron-hole pairs by a Z-scheme mechanism. The reduced metallic Ag nanoparticles were found to function as centers for the transfer of electrons from AgBr to PI. This work has revealed a new application for the aerogel PI/AgBr@Ag photocatalyst in environmental protection.

Surface Sizing Treated MWCNTs and Its Effect on the Wettability, Interfacial Interaction and Flexural Properties of MWCNT/Epoxy Nanocomposites.

A surface-sizing technique was offered to take full advantage of multi-walled carbon nanotubes (MWCNTs) and epoxy resins. Two surface-sizing treated MWCNTs were obtained through a ball-milling treatment of amino-functionalized MWCNTs (MWCNT-NH2) with n-butyl glycidylether (BuGE) and benzyl glycidylether (BeGE). These were referred to as MWCNT-BuGE and MWCNT-BeGE. The results indicated that the surface sizing effectively enhanced wettability, dispersibility of MWCNTs in the epoxy resin. These ameliorating effects, along with improved interfacial interaction between MWCNT-BeGE containing benzene rings and the epoxy matrix, which can offer a more efficient local load-transfer from matrix to MWCNTs, as observed by a higher G-band shift in Raman spectrum under bending loads than that of MWCNT-BuGE reinforced ones. Correspondingly, MWCNT-BeGE/epoxy nanocomposites exhibited increasing flexural strength and modulus of 22.9% and 37.8% respectively compared with the neat epoxy, and 7.3% and 7.7% respectively compared with MWCNT-BuGE/epoxy nanocomposites with the same MWCNT content.

Z-scheme Ag3PO4/POM/GO heterojunction with enhanced photocatalytic performance for degradation and water splitting.

To develop solar light-driven photocatalysts with high activity and structural stability, Ag3PO4/POM/GO heterojunction has been successfully prepared by a facile method at room temperature. Ag3PO4/POM/GO shows remarkably enhanced activity and stability for photocatalytic degradation and H2 production from water-splitting under simulated solar light. The degradation rate of Ag3PO4/POM/GO is 1.8 times and 1.2 times those of Ag3PO4 and Ag3PO4/POMs, respectively. H2 production using Ag3PO4/POM/GO is 2.0 times that of Ag3PO4/GO. The enhanced photocatalytic performance of Ag3PO4/POM/GO is attributed to the increased surface area, electronegativity and structure stability. The Z-scheme system of Ag3PO4/POM/GO effectively promotes charge separation, resulting in enhanced photocatalytic performance under simulated solar light.

Facile synthesis of silver/silver thiocyanate (Ag@AgSCN) plasmonic nanostructures with enhanced photocatalytic performance.

A nanostructured plasmonic photocatalyst, silver/silver thiocyanate (Ag@AgSCN), has been prepared by a simple precipitation method followed by UV-light-induced reduction. The ratio of Ag to silver thiocyanate (AgSCN) can be controlled by simply adjusting the photo-induced reduction time. The formation mechanism of the product was investigated based on the time-dependent experiments. Further experiments indicated that the prepared Ag@AgSCN nanostructures with an atomic ratio of Ag/AgSCN = 0.0463 exhibited high photocatalytic activity and long-term stability for the degradation of oxytetracycline (84%) under visible-light irradiation. In addition to the microstructure and high specific surface area, the enhanced photocatalytic activity was mainly caused by the surface plasmon resonance of Ag nanoparticles, and the high stability of AgSCN resulted in the long-term stability of the photocatalyst product.

Hollow Ag/MnO2 Nanostructures with Controllable Shells: Synthesis and Oxygen Reduction Reaction Catalytic Performance.

Novel hollow Ag/MnO2 nanostructures with controlled shell composition and structure were designed and synthesized. In the present synthetic procedure, silver nanocrystals were oxidized by KMnO4 , and MnO2 was heterogeneously formed on the surface of silver nanocrystals, then released Ag+ was photoreduced to silver adjacent to MnO2 . By simply changing the photoreduction moment, simultaneously with or after the addition of KMnO4 , hollow Ag/MnO2 structures with different shell architectures-a monolayered shell composed of evenly mixed silver and MnO2 and a double-layered shell composed of an inner MnO2 layer and an outer silver layer-can be obtained. Furthermore, the morphology of the hollow structure can be tuned by selecting different silver precursors, and the ratio of silver to MnO2 in the shell can also be controlled by adjusting the ratio in the original reaction mixture. Electrochemical measurements revealed significantly enhanced catalytic performance in the oxygen reduction reaction for the prepared hollow structures. Compared with the Ag/MnO2 composite, the onset potentials positively shift by about 50.0 mV and limiting current densities are nearly 2.0 times higher.

Enhanced Catalytic Activity in Liquid-Exfoliated FeOCl Nanosheets as a Fenton-Like Catalyst.

A facile liquid-phase exfoliation method to prepare few-layer FeOCl nanosheets in acetonitrile by ultrasonication is reported. The detailed exfoliation mechanism and generated products were investigated by combining first-principle calculations and experimental approaches. The similar cleavage energies of FeOCl (340 mJ m(-2) ) and graphite (320 mJ m(-2) ) confirm the experimental exfoliation feasibility. As a Fenton reagent, FeOCl nanosheets showed outstanding properties in the catalytic degradation of phenol in water at room temperature, under neutral pH conditions, and with sunlight irradiation. Apart from the increased surface area of the nanosheets, the surface state change of the nanosheets also plays a key role in improving the catalytic performance. The changes of charge density, density of states (DOS), and valence state of Fe atoms in the exfoliated FeOCl nanosheets versus plates illustrated that surface atomistic relationships made the few-layer nanosheets higher activity, indicating the exfoliation process of the FeOCl nanosheets also brought about surface state changes.