High performance of boehmite/polyacrylonitrile composite nanofiber membrane for polymer lithium-ion battery

In this study, a novel boehmite/polyacrylonitrile (BM/PAN) composite nanofiber membrane was prepared using the electrospinning technique. The physical and electrochemical properties of different contents of BM/PAN composite nanofiber membranes were investigated as separators for lithium ion batteries (LIBs). Compared to the commercial polypropylene (PP) separator, the experimental results show that the BM/PAN composite nanofiber separator possesses a unique three-dimensional (3D) interconnected structure and exhibits higher porosity, greater electrolyte up-take, higher thermal stability and better electrochemical performance in a LiCoO₂/Li cell. Besides, batteries containing 30 wt% BM/PAN membranes display the highest ionic conductivity (2.85 mS cm⁻¹), widest electrochemical stability window (5.5 V vs. Li⁺/Li), leading to the highest initial discharge capacity (162 mA h g⁻¹) and the largest capacity retention ratio (90.7%) at 0.5C after 100 cycles. These findings reveal that the BM/PAN composite nanofiber membranes are promising candidates as commercial separators for high performance LIBs.

In this study, a novel boehmite/polyacrylonitrile (BM/PAN) composite nanofiber membrane was prepared using the electrospinning technique.     

Synthesis of MOFs/GO composite for corrosion resistance application on carbon steel

Two unreported metal–organic frameworks [Cu(6-Me-2,3-pydc)(1,10-phen)·7H₂O]_n (namely Cu-MOF) and [Mn₂(2,2′-bca)₂(H₂O)₂]_n (namely Mn-MOF) were synthesized by a solvothermal method and their structures were characterized and confirmed by elemental analysis, X-ray single crystal diffraction, Fourier infrared spectroscopy and thermogravimetric analysis. Cu-MOF/graphene (Cu-MOF/GR), Cu-MOF/graphene oxide (Cu-MOF/GO), Mn-MOF/graphene (Mn-MOF/GR) and Mn-MOF/graphene oxide (Mn-MOF/GO) composite materials were successfully synthesized by a solvothermal method and characterized and analyzed by PXRD, SEM and TEM. In order to study the corrosion inhibition properties of the Cu-MOF/GR, Cu-MOF/GO, Mn-MOF/GR and Mn-MOF/GO composite materials on carbon steel, they were mixed with waterborne acrylic varnish to prepare a series of composite coatings to explore in 3.5 wt% NaCl solution by electrochemical measurements and results showed that the total polarization resistance of the 3% Cu-MOF/GO and 3% Mn-MOF/GO composite coatings on the carbon steel surface were relatively large, and were 55 097 and 55 729 Ω cm², respectively, which could effectively protect the carbon steel from corrosion. After immersion for 30 days, the 3% Mn-MOF/GO composite still maintained high corrosion resistance, the |Z| values were still as high as 23 804 Ω cm². Therefore, MOFs compounded with GO can produce a synergistic corrosion inhibition effect and improve the corrosion resistance of the coating; this conclusion is well confirmed by the adhesion capability test.

Two unreported metal–organic frameworks [Cu(6-Me-2,3-pydc)(1,10-phen)·7H₂O]_n (namely Cu-MOF) and [Mn₂(2,2′-bca)₂(H₂O)₂]_n (namely Mn-MOF) were synthesized and characterized. Cu-MOF and Mn-MOF all can form a three-dimensional structure.     

The toxic effects of alizarin red S on catalase at the molecular level

Alizarin red S (ARS) is a widespread mordant dye derived from alizarin. However, it was reported to be mutagenic and carcinogenic probably because it could induce oxidative damages in organisms. Catalase (CAT) is an important antioxidant enzyme defensing oxidative damages induced by xenobiotics. The underlying mechanisms of ARS interacting with CAT have not been clarified yet. This study is conducted to characterize the functional and conformational changes on CAT by ARS and the binding details to further investigate their interaction mechanisms. Under exposure of ARS at 5 μM, CAT activity was significantly decreased to 76.2%. Inhibition of CAT probably resulted in promotion of intracellular oxidative stress and pro-oxidant property of ARS. The interaction between ARS and CAT was proved to be spontaneous and exothermic. However, limited structural changes were observed according to spectroscopic results. Results showed that ARS prefers to bind with residues buried in the active site and could alter the activity of CAT, which were agree with the molecular docking results. This work proves the adverse effects of ARS on CAT mainly at molecular level and further highlights its potential risks to heath.

Alizarin red S is confirmed to be toxic to catalase at molecular level attributing to the structural and functional changes of catalase.     

A ZrO2-RGO composite as a support enhanced the performance of a Cu-based catalyst in dehydrogenation of diethanolamine

The sintering resistance of supported Cu nanoparticle (NP) catalysts is crucial to their practical application in the dehydrogenation of diethanolamine (DEA). In this paper, co-precipitation, hydrothermal synthesis, and sol–gel condensation are used to form a new support material through chemical bonding between graphene oxide and ZrO₂. The composite carriers prepared by the three methods are mixed with copper nitrate and ground using a ball mill. A series of Cu/ZrO₂-reduced graphene oxide (RGO) composites were prepared by calcination under nitrogen at 450 °C for 3 h and hydrogen reduction at 250 °C for 4 h. The conversion of DEA to iminodiacetic acid (IDA) reached 96% with the Cu/ZrO₂-RGO catalyst prepared by hydrothermal synthesis. The conversion rate of DEA is more than 80% following the reuse of the CZG-2 catalyst for twelve cycles. The various physicochemical characterization techniques show that the Cu/ZrO₂-RGO layered and wrinkled nanostructures can improve catalytic stability and suppress the sintering of the supported Cu NPs during the catalytic dehydrogenation of diethanolamine. A synergistic effect between the RGO and the Cu nanoparticles is observed. The Cu nanoparticles with RGO have a better dispersibility, and a new nano-environment is created, which is the key to improving the efficiency of diethanolamine dehydrogenation. These new Cu/ZrO₂-RGO catalysts show increased durability compared to commercially produced Cu/ZrO₂ catalysts and show promise for practical applications involving diethanolamine dehydrogenation.

A Cu/ZrO₂-RGO catalyst prepared by hydrothermal synthesis of a ZrO₂-RGO carrier has highly dispersed Cu nanoparticles and resistance to sintering.     

Polymer-assisted synthesis and applications of hydroxyapatite (HAp) anchored nitrogen-doped 3D graphene foam-based nanostructured ceramic framework

In the present work, a hydroxyapatite anchored nitrogen-doped three-dimensional graphene (HAp-N3DG) skeletal network (foam) based nanostructured ceramic framework (CF) was developed through a polymer-assisted solvothermal route. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) studies reveal that the nano sized 0D HAp particles are anchored on the N3DG skeletal network with an average size of less than 50 nm. EDX and X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of Ca, P, O, N, and C. In addition, XPS analysis reveals the existence of N–C bonds in the prepared sample. The X-ray diffraction (XRD) patterns indicate the presence of hexagonal phase hydroxyapatite and the calculated average crystallite size was found to be 12 nm. The developed HAp-N3DG foam based nanostructured CF was found to have a mesoporous structure and the measured specific surface area (SSA) and the mean pore diameter were found to be 64.73 m² g⁻¹ and 23.6 nm, respectively. Electrochemical analysis shows that HAp anchored on nitrogen-doped 3D graphene foam based nanostructured CF has moderate electrochemical activity towards lithium ion charge/discharge. In addition, the prepared material showed adsorption activity values of 204.89 mg g⁻¹ and 243.89 mg g⁻¹ for the volatile organic compounds (VOCs) benzene and toluene, respectively. The present findings suggest that the newly developed HAp anchored nitrogen-doped 3DG (HAp-N3DG) skeletal network (foam) based nanostructured CF material can be used in energy devices and in the removal of volatile organic compounds. Moreover, the present study initiates a new kind of approach in energy device (lithium ion battery-LIB) research and in the removal of VOCs.

Hydroxyapatite anchored nitrogen-doped three-dimensional graphene (HAp-N3DG) skeletal network (foam) based nanostructured ceramic framework (CF) was developed through a polymer-assisted solvothermal route.     

Effect of polyethylene glycol on crystal growth and photocatalytic activity of anatase TiO2 single crystals

In order to evaluate the effect of polyethylene glycol (PEG) on the growth of TiO₂ crystals, anatase TiO₂ crystals with different morphologies and structures were synthesized by controlling the content and type of PEG in a solvothermal system. Then, their morphology and structure were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Characterization results show that hydrofluoric acid can promote the formation of high activity (001) facets. Experiments on the effect of PEG on crystal growth show that the low molecular weight PEG (PEG400) can accelerate crystal differentiation and relieve the agglomeration of crystals in the presence of hydrofluoric acid. Besides, according to the experimental results, we found that PEG400 can reduce the agglomeration size and number of TiO₂ polycrystalline particles. Research on the photocatalytic activity proposed that the independence of single crystal and the integrity of (001) facets are the critical factors in advanced oxidation reaction. The resultant anatase TiO₂ single crystals could produce more hydroxyl radicals (˙OH) in the photocatalytic system, which exhibited remarkable photocatalytic performance for the degradation of Acid Red B.

Anatase TiO₂ crystals with different structures were synthesized. Experiments on the effect of polyethylene glycol show that the low molecular weight PEG (PEG400) can accelerate crystal differentiation and relieve the agglomeration of crystals.     

Efficacy and safety of intraoperative intravenous methadone during general anaesthesia for caesarean delivery: a retrospective case-control study

BackgroundMost patients undergoing caesarean delivery with general anaesthesia require systemic opioid administration. Due to its rapid onset and long duration of action, intravenous methadone may make it suitable for analgesia after caesarean delivery. Intraoperative methadone combined with postoperative intravenous patient-controlled analgesia with fentanyl or morphine has recently been introduced in our unit.MethodsA retrospective case-control study of 25 patients who had received methadone was performed. Fifty control patients undergoing elective or emergency caesarean delivery were matched for the use of postoperative intravenous patient-controlled analgesia, transversus abdominis plane (TAP) block and regular non-steroidal anti-inflammatory drugs. Exclusion criteria included preoperative neuraxial analgesia or pre-delivery opioid consumption greater than 10 mg of intravenous morphine equivalents.ResultsPatients in the methadone group had lower pain scores and were less likely to require intravenous opioid supplementation in the post-anaesthetic care unit (P < 0.001). Opioid consumption over 48 h was significantly lower in the methadone group. Delayed discharge from the post-anaesthesia care unit was due to sedation in one patient in the methadone group compared to three control patients in whom it was due to sedation and inadequate analgesia.ConclusionA single intraoperative bolus of intravenous methadone appeared to provide effective analgesia with an acceptable side-effect profile.