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ObjectiveA method involving derivatization combined with liquid chromatography-tandem mass spectrometry was developed for the determination of vitamin D in infant formula food.MethodsThe samples were treated with enzymolysis， saponification， liquid-liquid extraction， and 4-phenyl-1，2，4-triazoline-3，5-dion derivatization. Chromatographic separation was performed using an Atlantis® T3 column， and gradient elution was performed using the methanol-5 mmol/L ammonium format solution as the mobile phase. The method applied positive electrospray ionization and multiple reaction monitoring mode and was quantified with the isotope internal standard method.ResultsA good linearity was obtained with a correlation coefficient above 0.99. The average recovery levels from three different ranged from 92.3% to 94.2%， and the relative standard deviations were between 3.03% and 5.34% （n=6）. The limit of quantification was 1 μg/kg.ConclusionThis method is simple， accurate with high sensitivity and high selectivity， and suitable for the determination of vitamin D in infant formula food.

Defining the copper-based catalysts that are responsible for the catalytic behaviour of oil-paper insulation systems and implementing effective regulation are of great significance. Accelerated ageing experiments were conducted to reveal variations in copper scales and deterioration in insulation properties. As ageing progressed, TEM images demonstrated that copper species were adsorbed and aggregated on the fibre surface in the form of nanoparticles (NPs). The scale of NPs exhibited a continuous increase, from 27.06 nm to 94.19 nm. Cu(I) and Cu(II) species were identified as the active sites for inducing intense free radical reactions, which significantly reduced the activation energy, making the insulating oil more susceptible to oxidation. The role of the antioxidant di-tert-butyl-p-cresol (DBPC) in extending the insulation life was regulated by determining the optimal addition time based on variations in the interfacial tension. After the second addition of DBPC, the ageing rates of the dissipation factor, acidity, micro-water and breakdown voltage in the Cu+DBPC group decreased by 28.8%, 43.2%, 52.9% and 46.7%, respectively, compared to the Cu group. This finding not only demonstrates the crucial role of DBPC in preventing the copper-based catalyst-induced oxidation of insulating oil, but also furnishes a vital foundation for enhancing the long-term stability of transformer insulation systems. [ABSTRACT FROM AUTHOR]

This study aims to develop a novel portable reversible thermochromic patch and evaluate its potential applications in temperature monitoring and indication. The film is based on the concept of electronic charge transfer thermochromic coatings, enabling accurate detection of high temperatures. Experimental results demonstrate that when the temperature of the monitored device's circuit reaches 70 °C or above, the color of the film changes from deep blue to colorless, indicating potential overheating in the power grid. Using salt spray corrosion testing and cycle performance testing, we validate the film's excellent corrosion resistance in harsh natural environments and its provision of reliable color indication. The film possesses portability and ease of attachment to various electrical devices and circuits requiring temperature sensing. By connecting the color information of the film to a computer system, we can achieve digital temperature monitoring, providing potential applications in future smart grid development. [ABSTRACT FROM AUTHOR]

In the last decade, oil-based titanium dioxide nanofluids (TiO2 NFs) have gained immense interest due to their unique insulating properties and excellent thermal performance, which endow them with the potential for application in the field of modified insulating oils. A timely comparison, analysis and summary of recent advances in the preparation, characterization, and properties of different oil-based TiO2 NFs for oil-immersed power transformers will contribute to provide a useful reference for the subsequent development of such materials. Preparation methods are reviewed along with their merits and demerits. Characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical microscopy (OM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, thermally stimulated current (TSC), pulse electroacoustic technique (PEA), finite element analysis (FEA), fluorescence spectroscopy, Raman spectroscopy and zeta potential analysis are all applied to determine the crystal structure, particle size, surface function, surface charge and stability. Stabilization mechanisms are also discussed in detail. Some critical properties of oil-based TiO2 NFs under the application of different influencing factors such as base oils, crystal structure, size of nanoparticles, surface modifiers, mixing percentage, and aging environment are highlighted. Finally, the existing challenges and perspectives are presented for future research. [ABSTRACT FROM AUTHOR]

A series of epoxy resins containing various trifluoromethyl groups were synthesized and thermally cured with diaminodiphenylmethane (DDM) and aminophenyl sulfone (DDS). All epoxy resins exhibited excellent thermal stability with the glass transition temperatures of above 128 °C and 5% weight loss temperatures of above 300 °C. DDS-cured epoxy resins possessed higher thermal stability than that of DDM-cured epoxy resins, while DDM-cured epoxy resins showed better mechanical, dielectric, and hydrophobic properties. Additionally, DDM-cured epoxy resins with different locations and numbers of trifluoromethyl groups showed flexural strength in the range of 95.55~152.36 MPa, flexural modulus in the range of 1.71~2.65 GPa, dielectric constant in the range of 2.55~3.05, and water absorption in the range of 0.49~0.95%. These results indicate that the incorporation of trifluoromethyl pendant groups into epoxy resins can be a valid strategy to improve the dielectric and hydrophobic performance. [ABSTRACT FROM AUTHOR]

The detection of dissolved gas in transformer oil is of vital importance to diagnose the early fault and monitor the security and stability of power systems. In this work, distinct Pd/C, Pd/C-R and Pd/NC were synthesized and evaluated. XRD and XPS characterizations show that both Pd0 and PdII are presented over the surface of carbon host for Pd/C, while poor gas-sensitive properties were presented for Pd0 in H2-reduced Pd/C-R sample. High content of cationic PdII species are synthesized by nitrogen doping of the carbon surface for Pd/NC. The experimental results showed that the gas-sensitive performances of H2/CO/C2H2 gases is facilitated over the developed Pd/NC material. This study can provide reference for the rapid detection and fault diagnosis of faulty gases in transformers. [ABSTRACT FROM AUTHOR]

Background and Purpose: Epidemiological studies on low back pain in residents living in mountainous areas are scarce. The study was aimed at investigating the prevalence and associated factors of low back pain in Chongqing, relatively impoverished mountainous areas of China. Materials and Methods: This was a cross-sectional study conducted at selected community or village health service centers in Chongqing over a 2-month period (May 2021 to June 2021), which included adults of Chongqing aged > 18 years with or without low back pain (N=1820) chosen by stratified, cluster-sampling. Associated factors of low back pain including sociodemographic characteristics, lifestyle, and occupational features were collected, along with medical history, Oswestry Disability Questionnaire (ODI), and Numerical Rating Scale (NRS) of patients with low back pain, and carried out for at least 20 minutes per respondent. Univariate and multivariate logistic regression models were utilized for statistical analysis. Results: Overall, 30.5% of 1704 respondents presented with low back pain, with 26.3% living in flat areas and 35.6% in mountainous areas. The associated factors of low back pain were mountainous area residence (OR 1.4, 95% CI 1.1– 1.8), advanced age (OR 1.8, 95% CI 1.3– 2.5 for those aged 45– 59 years, OR 2.3, 95% CI 1.6– 3.4 for those aged 60– 74 years, and OR 2.1, 95% CI 1.2– 3.6 for those aged ≥ 75 years), married or remarried (OR 1.9, 95% CI 1.1– 3.2), divorced or widowed (OR 2.7, 95% CI 14– 5.4), moderate labor intensity (OR 1.4, 95% CI 1.1– 1.8), frequent stoop (OR 1.6, 95% CI 1.1– 2.4), and depressed mood (OR 1.6, 95% CI 1.2– 2.1). Residents in the mountainous areas had a higher score on Oswestry Disability Questionnaire (8.3 [SD 6.3] vs 6.2 [SD 4.3]) than those in flat areas. Conclusion: Mountainous areas in Chongqing had higher prevalence of low back pain as 35.6%, compared with 26.3% in flat areas, with more severe dysfunction in low back pain patients. Multifactorial analysis found that the factors associated with low back pain in Chongqing residents included mountain residence, labor intensity, stoop, psychological factors and frequency of exercise. [ABSTRACT FROM AUTHOR]

The neuromorphic network based on artificial neurons and synapses can solve computational difficulties, and its energy efficiency is incomparable to the traditional von Neumann architecture. As a new type of circuit component, nonvolatile memristors are very similar to biological synapses in structure and function. Only one memristor can simulate the function of a synapse. Therefore, memristors provide a new way to build hardware-based artificial neural networks. To build such an artificial neural network, in addition to the artificial synapses, artificial neurons are also needed to realize the distribution of information and the adjustment of synaptic weights. As the VO2 volatile local active memristor is complementary to nonvolatile memristors, it can be used to simulate the function of neurons. However, determining how to better realize the function of neurons with simple circuits is one of the current key problems to be solved in this field. This paper considers the influence of distribution parameters on circuit performance under the action of high-frequency and high-speed signals. Two Mott VO2 memristor units are connected and coupled with microstrip lines to simulate the Hodgkin–Huxley neuron model. It is found that the proposed memristor neuron based on microstrip lines shows the characteristics of neuron action potential: amplification and threshold. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mango anthracnose is among the most severe diseases impacting mango yields and quality. While this disease can be effectively controlled through chemical means, it is vital that appropriate field efficacy and fate determination studies be conducted when applying pesticides to crops in order to appropriately gauge the ecological and health risks associated with the use of these agents. RESULTS: GAP field trials were conducted to explore the efficacy, dissipation, and terminal residues associated with the application of mefentrifluconazole and pyraclostrobin to mango crops in six locations throughout China. These analyses revealed that three applications of mefentrifluconazole [160 mg active ingredient (a.i.) kg−1] in combination with pyraclostrobin mixture achieved satisfactory disease control efficacy. To simultaneously detect mefentrifluconazole and pyraclostrobin residues on mangoes, a 'quick, easy, cheap, effective, rugged and safe' (QuEChERS) high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS)‐based approach was established. The initial mefentrifluconazole and pyraclostrobin concentrations ranged from 0.18 to 0.34 mg kg−1, and these two compounds exhibited respective half‐lives of 5.6 to 10.8 days and 5.5 to 9.0 days. At 21 days following foliage application, the terminal mefentrifluconazole and pyraclostrobin residue concentrations were 0.02–0.04 and 0.01–0.04 mg kg−1, with these concentrations being below the maximum residue limit (MRL) established for pyraclostrobin. Both short‐term [acute reference dose percent (ARfD%) 0.78–2.36% and 2.0–6.08%] and chronic [acceptable daily intake percent (ADI%) 0.08–0.47% and 0.09–0.55%] dietary intake risk assessments for mefentrifluconazole and pyraclostrobin indicated that these terminal residue concentrations are acceptable for the general population. CONCLUSION: Mefentrifluconazole and pyraclostrobin in mango was rapidly degraded following first‐order kinetics models. The dietary risk of mefentrifluconazole and pyraclostrobin through mango was negligible to consumers. The application of a 400 g L−1 mefentrifluconazole–pyraclostrobin suspension concentrate mixture represents a highly efficacious fungicidal approach to controlling mango anthracnose that exhibits significant potential for development as it is easily degraded and associated with low residual concentrations after application. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study established a QuEChERS high-performance liquid chromatography/tandem triple-quadrupole mass spectrometry method for determining azoxystrobin, pyraclostrobin, picoxystrobin, difenoconazole, chlorantraniliprole, imidacloprid, and cyantraniliprole and its metabolite (IN-J9Z38) in litchi and longan, and applied this method to the real samples. The residues in samples were extracted with acetonitrile and purified with nano-ZrO2, C18, and PSA. The samples were then detected with multireactive ion monitoring and electrospray ionization in the positive ion mode and quantified using the external matrix-matched standard method. The results showed good linearities for the eight analytes in the range of 1–100 μg/L, with correlation coefficients (r2) of >0.99. The limit of quantification was 1–10 μg/kg, and the limit of detection was 0.3–3 μg/kg. Average recovery from litchi and longan was 81–99%, with the relative standard deviation of 3.5–8.4% at fortified concentrations of 1, 10, and 100 μg/kg. The developed method is simple, rapid, efficient, and sensitive. It allowed the rapid screening, monitoring, and confirming of the aforementioned seven pesticides and a metabolite in litchi and longan. [ABSTRACT FROM AUTHOR]

A series of block sulfonated poly(arylene ether ketone) (SPAEK) copolymers with different block lengths and ionic contents were synthesized by a two-stage process. The morphology of these block SPAEK copolymers was investigated by various methods, such as differential scanning calorimetry (DSC), transmission electron microscope (TEM), and small angle X-ray scattering (SAXS). Dark colored ionic domains of hundreds of nanometers spreading as a cloud-like belt were observed in TEM images. The sizes of the ionic domains as a function of block copolymer composition were determined from SAXS curves. The results for the evolution of ionic domains revealed that the block copolymers exhibited more clearly phase-separated microstructure with increasing ionic contents and hydrophobic sequence lengths. Proton conductivity is closely related to the microstructure, especially the presence of large interconnected ionic domains or ionic channels. Block SPAEK membranes have interconnected ionic clusters to provide continuous hydrophilic channels, resulting in higher proton conductivity. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In order to prepare a hybrid proton exchange membrane with low methanol permeability and high proton conductivity, two silane monomers, namely 3-glycidoxypropyl-trimethoxysilane (GPTMS) and 3-mercaptopropyl-trimethoxysilane (MPTMS) are first blended with a sulfonated poly(arylene ether ketone) (SPAEK). Then the blended membrane is heated to induce the grafting of GPTMS onto SPAEK. Finally, a hydrolysis-condensation is performed on the grafted membrane to induce cross-linking. The –SH groups of MPTMS are oxidized to sulfonic acid groups, which are attributed to enhance the proton conductivity of hybrid membranes. Fourier transform infrared spectroscopy is used to characterize and confirm the structures of SPAEK and these cross-linked hybrid membranes. The proton conductivity of a cross-linked hybrid membrane G50M50 reaches up to 0.20Scm−1 at 80°C, which is comparable to that of SPAEK and much higher than that of Nafion. Meanwhile, the methanol permeability is nearly three times lower than that of Nafion and two times lower than that of SPAEK. The ion-exchange capacity, water uptake, membrane swelling and thermal stability are also investigated to confirm their applicability in fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a new type of cross-linked composite membrane is prepared and considered for its potential applications in direct methanol fuel cell. Nafion and sulfonated poly(arylene ether ketone) bearing carboxylic acid groups (SPAEK-C) are blended and subsequently cross-linked by a Friedel–Craft reaction using the carboxylic acid groups in the SPAEK-C to achieve lower methanol permeability. The perfluoroalkyl sulfonic acid groups of Nafion act as a benign solid catalyst, which assist the cross-linking of SPAEK-C. The physical and chemical characterizations of the cross-linked composite membranes are performed by varying the contents of SPAEK-C. The c-Nafion-15% membrane exhibits appropriate water uptake (10.49–25.22%), low methanol permeability (2.57×10−7 cm2 s−1), and high proton conductivity (0.179Scm−1 at 80°C). DSC and FTIR analyze suggest the cross-linking reaction. These results show that the self-cross-linking of SPAEK-C in the Nafion membrane can effectively reduce methanol permeability while maintaining high proton conductivity. [Copyright &y& Elsevier]

Abstract: To prepare a novel covalently cross-linked proton exchange membrane with high proton conductivity, sulfonated poly(arylene ether ketone)s bearing carboxylic acid groups (SPAEK-C) and o-diamino functional polybenzimidazole oligomers (PBI) were consequently synthesized. Then the SPAEK-C/PBI blend membranes were dried at 110°C for 3h to induce cross-links between amino groups of PBI oligomer and carboxylic acid groups of SPAEK-C. 1H NMR measurements and Fourier transform infrared spectroscopy were used to characterize and confirm the structures of SPAEK-C, PBI oligomers and the cross-linked membranes. The cross-linked membranes were immersed in various concentrations of phosphoric acid solution to enhance proton conductivity. These H3PO4 doped SPAEK-C/PBI membranes displayed comparable or even higher proton conductivity than that of Nafion 117, especially under low humidity conditions. Moreover, the water uptake, acid uptake, mechanical and thermal stability were also investigated in detail. [Copyright &y& Elsevier]

Abstract: To prepare a cross-linked hybrid proton exchange membrane with high mechanical and oxidative stability, a silane monomer, namely 3-glycidoxypropyltrimethoxysilane (KH-560), is first grafted to sulfonated poly(arylene ether ether ketone)s bearing carboxyl groups (SPAEK-C) and hydrolysis–condensation is then performed on the grafted membranes to make them cross-link. 1H NMR measurements and Fourier transform infrared spectroscopy are used to characterize and confirm the structures of SPAEK-Cs and hybrid polymer electrolyte membranes, respectively. The Si–O–Si cross-linking structure enhances the stability of the PEM greatly. The proton conductivities of the hybrid membranes with 5% KH-560 in weight reach 0.155Scm−1 at 80°C which is comparable to that of Nafion® membranes. The ion-exchange capacity, water uptake and swelling, methanol permeability, mechanical properties are investigated to confirm their applicability in fuel cells. [Copyright &y& Elsevier]

The article presents information on a study which described the synthesis of sulfonated poly(aryl ether ketone)s (SPAEK) copolymers by aromatic nucleophilic polycondensation from 3,3', 5,5'-tetramethyl-4, 4'-biphenol, 1,4-bis(4-fluorobenzoyl) benzene, and disulfonated difluorobenzophenone. A review of the related literature is given. It compares the series of SPAEK copolymers to poly(aryl ether ether ketone)s (SPEEK), poly(aryl ether ether ketone ketone)s (SPEEKK) and Nafion membranes.

• A series of sustainable epoxy resin/diatomite composites were prepared from bio-based epoxy resin and silanized natural diatomite • The diatomite is uniformly dispersed in the matrix without large-scale agglomeration. • The thermal and mechanical stability are significantly improved after the incorporation of diatomite. • BEF-EP/diatomite composites show good hydrophobic characteristic. In this study, a series of sustainable epoxy resin/diatomite composites were prepared by using the synthetic bio-based 2,2′-diglycidyl ether-3,3′-dimethoxy-5,5′-diallyl diphenylmethane (BEF-EP) as the matrix resin and silanized natural diatomite as the reinforcing filler. After cured with methylnadic anhydride and benzimidazole at different proportions of diatomite fillers, the morphology and properties of BEF-EP/diatomite composites were investigated and compared in detail. Due to the good compatibility between the epoxy resin matrix and silanized diatomite, the diatomite is uniformly dispersed in the matrix without large-scale agglomeration. With the addition content of diatomite increasing, the storage modulus of BEF-EP/diatomite composites increased from 2281 to 2983 MPa at 25 °C. The initial degradation temperature (T d5%) showed an increasing first and then decreasing tendency as the content of diatomite increased, while the T d50% and T dmax values of BEF-EP/diatomite composites also increase with the content of diatomite increasing. Especially, BEF-EP/diatomite 20% showed excellent thermal stability with T d5% of 287 °C, T d50% of 485 °C, and T dmax of 412 °C. The results indicated that the mechanical and thermal stability of epoxy resin composites could be significantly improved after the incorporation of diatomite. Furthermore, the bio-based BEF-EP/diatomite composite could be used as the renewable and sustainable alternatives to petroleum-based epoxy resin composites. [ABSTRACT FROM AUTHOR]

Background: Breast cancer is one of the most commonly diagnosed cancers in women, with high morbidity and mortality. Tumor metastasis is implicated in most breast cancer deaths; thus, inhibiting metastasis may provide a therapeutic direction for breast cancer. In the present study, pyropheophorbide-α methyl ester-mediated photodynamic therapy (MPPa-PDT) was used to inhibit metastasis in MCF-7 breast cancer cells.Methods: Uptake of MPPa was detected by fluorescence microscopy. Cell viability was evaluated by the Cell Counting Kit-8 (CCK-8). ROS generation was detected by 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). The migration of cells was assessed by wound healing assay, and invasion ability was assessed by Matrigel invasion assay. Levels of MMP2 and MMP9 were measured by PCR. Akt, phospho-Akt (Ser473), phospho-NF-κB p65 (Ser536) and NF-κB p65 were measured by western blotting. The F-actin cytoskeleton was observed by immunofluorescence. Lung tissue was visualized by hematoxylin and eosin staining.Results: Following MPPa-PDT, migration and invasion were decreased in the MCF-7 cells. MPPa-PDT downregulated the expression of MMP2 and MMP9, which are responsible for the initiation of metastasis. MPPa-PDT reduced the phosphorylation of Akt and NF-κB. MPPa-PDT also reduced the expression of F-actin in cytoskeleton in MCF-7 cells. These effects were blocked by the reactive oxygen species scavenger NAC or the Akt activator SC79, while the PI3K inhibitor LY294002 or the Akt inhibitor triciribine enhanced these effects. Moreover, MPPa-PDT inhibited tumor metastasis and destroyed F-actin in vivo.Conclusion: Taken together, these results demonstrate that MPPa-PDT inhibits the metastasis of MCF-7 cells both in vitro and in vivo and may be involved in the Akt/NF-κB-dependent MMP-9 signaling pathway. Thus, MPPa-PDT may be a promising treatment to inhibit metastasis. [ABSTRACT FROM AUTHOR]

Abstract: A novel poly(ether ether ketone) (PEEK) containing pendant carboxyl groups has been synthesized by a nucleophilic polycondensation reaction. Sulfonated polymers (SPEEKs) with different ion exchange capacity are then obtained by post-sulfonation process. The structures of PEEK and SPEEKs are characterized by both FT-IR and 1H NMR. The properties of SPEEKs as candidates for proton exchange membranes are studied. The cross-linking reaction is performed at 140°C using poly(vinyl alcohol) (PVA) as the cross-linker. In comparison with the non-cross-linked membranes, some properties of the cross-linked membranes are significantly improved, such as water uptake, methanol resistance, mechanical and oxidative stabilities, while the proton conductivity decreases. The effect of PVA content on proton conductivity, water uptake, swelling ratio, and methanol permeability is also investigated. Among all the membranes, SPEEK-C-8 shows the highest selectivity of 50.5×104 Sscm−3, which indicates that it is a suitable candidate for applications in direct methanol fuel cells. [Copyright &y& Elsevier]