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Transition metal-free direct and base-catalyzed 1,2-diborations of arylacetylenes using pinB-BMes2 provided a syn/anti-isomeric mixture of diborylalkenes. The kinetic analysis showed that the reaction rate and isomer ratio were affected by reaction conditions and substituents on the aryl ring. DFT calculations indicated that direct addition proceeded via the interaction of acetylene-π with the BMes2 fragment. In contrast, for the base-catalyzed diboration, the previously isolated sp2–sp3 diborane and borataallene were confirmed as stable intermediates by calculations. The whole reaction pathways can be divided into the Bpin-migration and deprotonation steps, where the borataallene should be considered as a common intermediate. It should be noted that the deprotonation step is reversible and affords the kinetically less favoured isomer under the thermodynamic conditions. As a result, the composition of isomeric products, in the base-catalyzed diboration, is attributed to the small difference of activation barriers between direct and base-catalyzed systems.

Metal-oxide catalysts have great potential in efficient CO2 electroreduction (CO2ER). Unfortunately, many catalysts exhibit limited selectivity for carbon products at the high current density. Here, density functional theory is applied to analyzethe active sites on SnO2 matrix surface. The theoretical analysis indicates that the elimination of oxygen atoms from SnO2 matrix can significantly improve CO2 activation and suppress H2. Inspired by the analysis, a series of defect-engineered SnO2 nanocubes are synthesized. The as-prepared SnO2 with rich oxygen vacancy (Vo-rich SnO2) possesses C1 selectivity of 92.5% at −44.2 mA cm−2 which is higher than pristine SnO2 (78.1% at −18.2 mA cm−2), and reaches 30 h stability. Furthermore, the CO2ER activity in a 10% CO2 atmosphere is studied for the first time, where Vo-rich SnO2 demonstrates C1 selectivity of 74.5%. This work testifies the potential of theory-guided strategy to design practicaltin-oxide electrocatalysts and firstly highlights the research of industrial flue gas for CO2ER.

High-performance electrode materials derived from biomass for supercapacitors have been considered as an effective solution to the problems of the fossil energy shortage and the environment deterioration. Most importantly, the specific capacitance, rate performance and cyclic stability for these electrode materials are focused issues. Here, we prepare a new type porous carbon using laminaria japonica as the carbon source via a simple carbonization and activation method, and investigate its morphology, structure and electrochemical properties. The results show that the porous carbon materials exhibit amorphous structure, high specific surface area with abundant pores and oxygen functional groups. The specific capacitance of the porous carbon with a large specific surface area of 1902.42 m2 g−1 and total pore volume of 1.26 cm3 g−1 can reach to 192 F g−1 at 0.1 A g−1. Furthermore, this porous carbon possesses a specific capacitance of 120 F g−1 at 10 A g−1, nearly 100% capacitance retention rate and coulomb efficiency after 10000 cycles at 1 A g−1, indicating excellent rate performance and cyclic stability. Therefore, as-prepared porous carbons derived from laminaria japonica with low cost, easy availability, high regeneration ability and sustainability have a promising application as the electrode materials for supercapacitors.

The aim of this paper is twofold. Firstly, we study the non-existence of finite order meromorphic solutions to the Cubic type of Fermat functional equation $$f(z)^3-3\tau f(z)f(z+c)+f(z+c)^3=1$$. In addition, the paper is concerned with the description of finite order entire solutions of the Quadratic type of Fermat functional equation $$f(z)^2-2\mu f(z)f(z+c)+f(z+c)^2=1$$.

Activated carbon (AC) electrodes applied in capacitive deionization (CDI) are usually prepared by coating activated materials on current collector, accompanying with low mass loading, poor areal salt adsorption capacity (SACA) and undesired volumetric salt adsorption capacity (SACV). Herein, we report preparation of free-standing AC electrodes by a simple mold-casting method. Unlike conventional coating methods, activated materials were well-dispersed together with binders to obtain a uniform suspension and then submitted for mold-casting preparation of electrodes. This new strategy helps to produce rational structure for porous free-standing AC electrodes by alleviating the blocking effect of pores. Obtained electrodes not only exhibit pretty good electrical conductivity and hydrophilicity, but also show excellent mechanical stability and water tolerance. The electrodes deliver both high SACA of 0.49 mg/cm2 and SACV of 2.48 mg/cm3. By virtue of the free-standing feature, a CDI device comprising 6 as-made units was built for demonstration, which exhibits a promising SACV of 2.01 mg/cm3 in NaCl aqueous solution. This work not only offers a simple method to prepare free-standing AC electrodes with extraordinary high mass loading (55 mg/cm2) and excellent salt adsorption capacity, but also provides good opportunity for large-scale application of CDI technology by substantially improving packing volumetric density.

A series of Ag/P-g-C3N4 composites with different Ag content were synthesized for the first time by thermal polymerization combined with photo-deposition method. The composites were characterized by X-ray powder diffraction, field emission scanning electron microscope coupled with energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectra, N2 absorption-desorption and X-ray photoelectron spectroscopy. Ag was successfully dispersed on the surface of P-g-C3N4. The photocatalytic performance of P-g-C3N4 and Ag/P-g-C3N4 was evaluated by degrading sulfamethoxazole (SMX) under visible light irradiation. In the presence of 5% Ag/P-g-C3N4, 100% of SMX was degraded within 20 min. The enhanced photocatalytic activity of Ag/P-g-C3N4 was attributed to the surface plasmon resonance effect of metallic Ag and Schottky barrier formed on the interface between Ag and P-g-C3N4, which could speed up the generation rate of electrons and holes and inhibit the recombination of photogenerated electron-hole pairs. The radical quenching tests indicated that holes and superoxide radicals were the dominant active species involved in SMX degradation. The synthesized materials maintained high catalytic activity after five cycle runs. The concentration and the intermediates during the degradation process were determined by LC–MS/MS, and the tentative degradation pathways of SMX in photocatalytic system were proposed.

Several mononuclear complexes with structure of [TpyRu2+(Py)2Cl]+ and [TpyRu2+(Isoq)2Cl]+ have been designed and synthesized. The structures of these complexes were confirmed by NMR and ESI-MS, the properties of all catalysts were also characterized optically and electrochemically. Water oxidation experiments were examined by turnover numbers (TONs), which showed the catalytic properties of all catalysts. In comparison, pyridine functionalized 1a-1d have more catalytic activities than isoquinoline coordinated complexes 2a-2d. It was also observed that attached polycyclic aromatic groups on the terpyridines had limited impact on catalytic activities. Among these ruthenium complexes, Ph-TpyRu2+(Py)2Cl exhibited the highest TON of 897.

Two-dimensional hierarchically porous carbon nanosheets obtain tremendous attention as advanced energy storage materials for supercapacitors applications. However, the effective synthesis of carbon materials simultaneously owning ultrathin layered nanosheets and hierarchically porous structure is a big challenge. In this work, we develop an interlayer-confined inorganic/organic coordination synthesis strategy to prepare ultrathin hierarchically porous carbon nanosheets. Iron (III) chloride hexahydrate is deliberately used as a host for intercalated coordination reaction with 2-aminophenol, where the formed inorganic/organic complex is carbonized to obtain ultrathin two-dimensional hierarchically porous carbon nanosheets. The optimized sample exhibits a thickness of 1.8 nm, high in-plane porosity, and a high capacitance of 315 F g−1 at 0.5 A g−1 in 6.0 M KOH aqueous electrolyte. A symmetric supercapacitor based on the carbon nanosheets delivers 17.8 Wh kg−1 and 79.2 Wh kg−1 output in KOH aqueous solution and EMIMBF4 electrolytes, respectively. The outstanding supercapacitor performance of this sample is attributed to a comprehensive effect of ultrathin feature, large specific surface area, well-defined in-plane pores, and elemental N-doping. This work presents a facile strategy to obtain carbon electrode materials with new nanostructure for future energy storage applications.

Mesoporous carbon/graphene composites (MCG) have exhibited good electrochemical performances; however, the fixed mesoporous carbon, the low specific surface area, and porosity are the main obstacles in their application in supercapacitors. In this paper, mesoporous carbon microspheres/graphene composites (MCMG) were synthesized in situ via a soft template method and subsequent thermal reduction by using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent, and aqueous mesophase pitch (AMP) and graphene oxide (GO) as the carbon sources. The strong electrostatic interaction between GO/CTAB and AMP promoted the self-assembly of CTAB and AMP to form the MCMG precursor. The results showed that the CTAB concentration and aging temperature have an important effect on the morphology and pore structure of the synthesized MCMG. The high aging temperature promoted the formation of mesoporous carbon spheres and its diameter increased with the increase in the concentration of CTAB. The as-prepared MCMG at the aging temperature of 140 °C had obvious spherical and layered carbon materials after carbonization at 900 °C. When the concentration of CTAB was 10.6 g L−1, the formed mesoporous carbon spheres with the diameter of 30–40 nm were uniformly dispersed among the layered graphenes in MCMG-140-0.2 (the aging temperature of 140 °C and the CTAB content of 0.2 g). In addition, its specific surface area was 1150.5 m2 g−1 and the mesopore size was centered at 4.3 nm, 7.9 nm, and 17.1 nm. Compared with the MCMG precursor, the ordered degree of the mesopores for MCMG was reduced due to the high temperature carbonization. Importantly, the specific capacitance of MCMG-140-0.2 at the current density of 0.1 A g−1 was as high as 356.3 F g−1. Moreover, the specific capacitance of MCMG-140-0.2 at 1 A g−1 remained at 278.5 F g−1, the capacitance retention was 92.1% after 6000 cycles, and the coulombic efficiency was over 98% at a high current density of 2 A g−1. Therefore, the as-prepared MCMG can be an excellent candidate for electrode materials in supercapacitors.

Wearable electronics, electronic skins, and human-machine interfaces demand flexible sensors with not only high sensitivity but also a wide linear working range. The latter remains a great challenge and has become a big hurdle for some of the key advancements imperative to these fields. Here, we present a flexible capacitive pressure sensor with ultrabroad linear working range and high sensitivity. The dielectric layer of the sensor is composed of multiple layers of double-sided microstructured ionic gel films. The multilayered structure and the gaps between adjacent films with random topography and size enhance the compressibility of the sensor and distribute the stress evenly to each layer, enabling a linear working range from 0.013 to 2063 kPa. Also, the densely distributed protrusive microstructures in the electric double layer contribute to a sensitivity of 9.17 kPa

Previously reported HPLC-evaporative light scattering detection methods for terpene trilactone determination in Ginkgo biloba leaf extract (EGBL) have complicated sample preparation steps and are time-consuming. Thus, in this work, an HPLC-MS method for the determination of terpene trilactones in EGBL was developed with a novel analytical quality by design approach to provide robust and simple measurements. For this purpose, analytical target profiles and systematic risk analyses were performed to identify potential critical method attributes and critical method parameters. After screening experiments, a Box-Behnken design approach was utilized to investigate the relationships between critical method attributes and critical method parameters. A hypercube design space obtained by a Monte Carlo method was used for choosing the analytical control strategy. Then, verification experiments were performed within the design space, and the models were found to be accurate. After that, the optimized method was verified and successfully used for quality control analysis of EGBL from different manufacturers, and the results were almost the same as those determined by HPLC-evaporative light scattering detection. To our knowledge, this is the first study to establish a robust HPLC-MS method for determination of terpene trilactones in EGBL based on a novel analytical quality by design concept, which can improve the quality control of commercial EGBL.

Glycation plays a pathogenic role in many age-related degenerative pathological conditions, such as diabetes, end-stage renal diseases, and cardiovascular diseases. Mass spectrometry-based qualitative and quantitative analysis methods have been greatly developed and contribute to our understanding of protein glycation. However, it is still challenging to sensitively and accurately quantify endogenous glycated proteome in biological samples. Herein, we proposed an integrated and robust quantitative strategy for comprehensive profiling of early-stage glycated proteome. In this strategy, a filter-assisted sample preparation method was applied to reduce sample loss and improve reproducibility of sample preparation, contributing to high-throughput analysis and accurate quantification of endogenous glycated proteins with low abundance. Standard glycated peptides were spiked and performed the subsequent process together with complex samples both in label-free quantification and multiple reaction monitoring (MRM) analysis, contributing to the improvement of quantitative accuracy. In parallel, a novel approach was developed for the synthesis of heavy isotope-labeled glycated peptides used in MRM analysis. By this way, a total of 1128 endogenous glycated peptides corresponding to 203 serum proteins were identified from 60 runs of 10 pairs of hemodialysis patients with and without cardiovascular complications, and 234 glycated peptides corresponding to 63 proteins existed in >70% runs, among which 17 peptides were discovered to be differentially glycated (P 1.5 or

The intensity of human activity, habitat loss and habitat degradation have significant impacts on biodiversity. Habitat quality plays an important role in spatial dynamics when evaluating fragmented landscapes and the effectiveness of biodiversity conservation. This study aimed to evaluate the status and characteristic variation in habitat quality to analyze the underlying factors affecting habitat quality in the Guangdong–Hong Kong–Macao Greater Bay Area (GBA). Here, we applied Kendall’s rank correlation method to calculate the sensitivity of habitat types to threat factors for the Integrated Valuation of Ecosystem Services and Tradeoffs habitat quality (InVEST-HQ) model. The spatiotemporal variation in habitat quality of the GBA in the period 1995–2015 was estimated based on the InVEST-HQ model. We analyzed the characteristic habitat quality using different ecosystem classifications and at different elevation gradients. Fractional vegetation cover, the proportion of impervious surface, population distribution and gross domestic product were included as the effect factors for habitat quality. The correlation between the effect factors and habitat quality was analyzed using Pearson’s correlation tests. The results showed that the spatial pattern of habitat quality decreased from fringe areas to central areas in the GBA, that the forest ecosystem had the highest value of habitat quality, and that habitat quality increased with elevation. In the period from 1995 to 2015, habitat quality declined markedly and this could be related to vegetation loss, land use change and intensity of human activity. Built-up land expansion and forest land fragmentation were clear markers of land use change. This study has great significance as an operational approach to mitigating the tradeoff between natural environment conservation and rapid economic development.

Introduction Charged aerosol detection (CAD) has the merits of high sensitivity, high universality and response uniformity. The strategy that combines the quantitative analysis of multi-components by single marker (QAMS) with CAD has certain advantages for the quantification of multi-components. However, relevant research was limited. Objectives To comprehensively investigate the crucial factors that affect the performance of the HPLC-CAD-QAMS approach and validate the credibility and feasibility of the method. Methodology Multiple components of Qishen Yiqi dripping pills (QSYQ) were assayed using the high-performance liquid chromatography (HPLC)-CAD-QAMS approach. Some factors that affect the sensitivity and accuracy of the approach were sufficiently studied. After the method verification, principal component analysis (PCA) was applied to evaluate the quality consistency of three types of samples: normal samples, expired samples and negative samples. Results A HPLC-CAD-QAMS method was successfully developed for the multi-component determination of QSYQ. First, chromatographic conditions were optimised by a definitive screening design, and the optimised ranges of operating parameters were obtained with a Monte Carlo simulation method. Next, a new method to select the internal reference standards was successfully introduced based on the heatmap of Pearson correlation coefficients of the response factors. Then, the multi-point method was selected to calculate the relative correction factors, and a robustness test was conducted with Plackett-Burman design. Finally, the PCA was proved to be effective for the quality consistency evaluation of different samples. Conclusion The developed HPLC-CAD-QAMS method can be a reliable and superior means for the multi-component quantitative analysis of QSYQ.

Recent years have seen a rapid development of electronic skin for wearable devices, autonomous robotics, and human-machine interaction. As a result, the demand for flexible pressure sensors as the critical sensing element in electronic skin is also increasing. These sensors need to feature high sensitivity, short response time, low detection limit, and so on. In this paper, inspired from the cobweb in nature, we propose a piezoresistive pressure sensor by forming a cobweb-like network made of a zinc octaethylphorphyrin (ZnOEP)/carbon nanotube (CNT) hybrid on an array of polydimethylsiloxane (PDMS) microposts. The hybrid material exhibits excellent adhesion to PDMS, benefitting from ZnOEP's low Young's modulus and the nonpolar bonding between ZnOEP and PDMS such that no delamination and resistance variation are found after thousands of cycles of bending and twisting. With the overhanging morphology of the ZnOEP/CNT network on the micropost array, we realized a pressure sensor with an ultrahigh sensitivity of 39.4 kPa-1, a super-fast response time of 3 ms, a low detection limit of 10 Pa, and a reproducible response without degradation after 5000 cycles of pressure loading/unloading. The sensor can be employed for a variety of applications, including wrist pulse measurement, sound level detection, mechanical vibration monitoring, etc., proving its great potential for use in electronic skin systems.

Hyperspectral image (HSI) classification is an important task in the remote sensing community. In general, many hyperspectral classification methods are based on pixel patch, which leads to information redundancy. In this paper, we propose a multi-scale encoder-decoder network for HSI classification. First, we adapt an encoder-decoder framework as the backbone network and use a skip connection between the encoder and decoder, the spatial information is obtained by this network. Second, we develop a multi-scale block to get the multi-scale information. Third, we retain complete spectral information through the constant number of spectral channels. Finally, an optimizer strategy is designed to achieve our model for the HSI classification task. We experiment with our method and other methods on two public datasets, and the results denote our model is useful for HSI classification task.

Perinatal exposure to bisphenol A (BPA) contributes to neurological disorders in offspring, but the underlying mechanisms are still poorly understood. The abnormal release of neuroactive metabolites in the tryptophan (TRP) and dopamine (DA) pathways is considered to be closely associated with some disorders. Thus, in this study, TRP and DA pathways in adult female mouse offspring were investigated when the pregnant mice were given either vehicle or BPA (2, 10, or 100 μg/kg/d) from day 6 of gestation until weaning. Then, the serum and brain samples of offspring were collected at 3, 6 and 9 months, and 12 neuroactive metabolites in the TRP and DA pathways were detected. The results showed that, in the TRP pathway, TRP levels decreased, whereas kynurenine (KYN) levels and TRP turnover increased in the brain. In the serum, TRP, KYN and 5-hydroxytryptamine (5-HT) levels decreased significantly. For the DA pathway, DA and DA metabolites, including 3,4-dihydroxyphenylacetic acid (DOPAC), 3-methoxytyramine (3-MT) and homovanillic acid (HVA), reduced significantly in the brain and serum. DA turnover decreased dramatically in the brain but enhanced in the serum. The disturbance of these two metabolic pathways might be one of the potential mechanisms of BPA-induced neuropsychiatric disorders.

The diboration of the C≡N bond in organic nitriles, and the N=N bond in azobenzene and pyridazine, by the highly Lewis‐acidic tetra(o‐tolyl)diborane(4) are reported. In the reactions with nitriles, azobenzene, and pyridazine, the addition of diborane(4) to the C≡N and N=N bonds was observed. Conversely, the N=N bond in phthalazine was cleaved by an addition/rearomatization sequence., ファイル公開：2020-01-02

Experimental investigations have been performed for a lab-scale hybrid rocket motor with hydrogen peroxide and paraffin-based propellants. A new paraffin-based solid fuel with favorable mechanical strength, consisting of 50 wt% paraffin, 20 wt% PE wax, 18 wt% EVA, 10 wt% SA and 2 wt% carbon, was proposed. The thermal properties of the proposed paraffin-based fuel and its components were firstly evaluated using TG/DTG measurements. It was found that the decomposition rates of each of the components of this paraffin-based fuel follow the order SA > pure paraffin > paraffin-based fuel blends > PE > EVA. Measurements of the regression rate of this paraffin-based fuel were performed and compared with results found in the literature. This showed that the regression rate of this paraffin-based fuel is much higher than that of traditional polymer solid fuels such as HTPB fuels. Finally, by adding a protrusion, a cavity and swirl blades at the end and in the middle of the combustion chamber, experimental investigations into the effects of a mix-enhancer on the paraffin-based hybrid rocket motor were performed. These investigations are discussed in detail.

A novel photocatalytic material that is phosphorus-doped and graphite-like (carbon nitride (g-C3N4)) was successfully prepared through direct thermal co-poly-condensation using ammonium dihydrogen orthophosphate as the phosphorus source and melamine as the g-C3N4 precursor. The catalyst was characterized by analyses from multiple tools: X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, BET surface area, ultraviolet–visible diffuse reflection spectroscopy, and X-ray photoelectron spectroscopy. The unique bubble-like structure provided the phosphorus-doped g-C3N4 (P-C3N4) with a unique property for spatial electron transfer and a large specific surface area (40.89 m2g-1). The photocatalytic performance of P-C3N4 was determined by assessing rhodamine B (RhB) degradation under visible-light irradiation. The results showed that P-C3N4 exhibited superior photocatalytic performance that is 18 and 4 times higher than pristine bulk g-C3N4 (B-C3N4) and modified multi-aperture g-C3N4 (M-C3N4), respectively. The enhancement of photocatalytic activity was attributed to the improved light harvesting capacity and the narrowing energy band structure of the copolymer that result from the substitution of phosphorus atoms by carbon atoms in the g-C3N4 framework. The photoelectron emission measurements confirmed that P-C3N4 promoted the separation efficiency of the charge carriers. The bubble-like structured P-C3N4 also possessed superior durability and stability. The radical quenching tests indicated that superoxide radicals ( O2−) and holes (h+) were the dominant active species for RhB degradation.

In this note, we study the admissible meromorphic solutions for algebraic differential equation fnf' + Pn−1(f) = R(z)eα(z), where Pn−1(f) is a differential polynomial in f of degree ≤ n − 1 with small function coefficients, R is a non-vanishing small function of f, and α is an entire function. We show that this equation does not possess any meromorphic solution f(z) satisfying N(r, f) = S(r, f) unless Pn−1(f) ≡ 0. Using this result, we generalize a well-known result by Hayman.

Carbon electrodes are of great importance in constructing high-performance capacitive deionization (CDI) devices. However, the use of conventional carbon electrodes for CDI is limited because of their poor mechanical stability and low mass loading. Herein, we report a binder-free, freestanding, robust, and ultrathick carbon electrode derived from a wood carbon framework (WCF) for CDI applications. The WCF inherits the unique structure of natural basswood, containing straightly aligned channels interconnected with highly ordered, open, and hierarchical pores. A CDI device based on thick WCF electrodes (1200 μm, equal to a mass loading of 50 mg cm–2) exhibits a remarkable areal salt adsorption capacity (SAC) of 0.3 mg cm–2, a high volumetric SAC of 2.4 mg cm–3, and a competitive gravimetric SAC of 5.7 mg g–1. Also, the good mechanical strength and water tolerance of the WCF electrodes improve the cycling stability of the CDI device. Finite element simulations of ion transport behavior indicate that the uniq...

In this paper we study the entire solutions to a certain type of difference-differential equations. We also give an affirmative answer to the conjecture of Zhang et al. In addition, our results improve and complement earlier ones due to Yang-Laine, Latreuch, Liu-Lü et al. and references therein.

Nitrogen and sulfur co-doped carbons are considered as electrode materials for high performance supercapacitors, while their further development is still limited by complicated synthesis procedure, unsatisfied structure and low energy density. Developing a simple synthetic strategy to obtain rationally structured carbon materials and high supercapacitor performance is remaining a grand challenge. Herein, we describe the synthesis of nitrogen and sulfur co-doped hierarchical porous carbons as high performance supercapacitors electrode by a methanesulfonic acid-assisted one-step carbonization and activation of the freeze-dried precursors mixture. The as-prepared carbon material not only exhibits ideally hierarchical pores, but also realizes uniform nitrogen and sulfur co-doping. In 6.0 M KOH electrolyte, the material can achieve a high specific capacitance of 272 F g−1 at 1.0 A g−1 and a promising rate performance retaining 172 F g−1 even at 100 A g−1. Moreover, a fabricated symmetric supercapacitor based on as-prepared nitrogen and sulfur co-doped hierarchical porous carbon delivers high energy densities of 12.4 W h kg−1 and 8.0 W h kg−1 in 6.0 M KOH liquid and KOH/PVA solid-state electrolytes, respectively. This work presents a simple and effective methanesulfonic acid-assisted approach for mass production of heteroatomic doping hierarchical porous carbons for future energy storage applications.

The reaction of highly Lewis acidic tetra(o-tolyl)diborane(4) with CO afforded a mixture of boraindane and boroxine by the cleavage of the C≡O triple bond. 13 C labeling experiments confirmed that the carbon atom in the boraindane stems from CO. Simultaneously, formation of boroxine 3 could be considered as borylene transfer to capture the oxygen atom from CO. The reaction of diborane(4) with t Bu-NC afforded an azaallene, while the reaction with Xyl-NC furnished cyclic compounds by direct C-H borylations.

The borylene-carbonyl moiety in [bis(silylene)B(CO)][WBr(CO)5 ] shows diverse reactivity. Reduction, migration, and complete cleavage of CO have been observed at the boron center, leading to the formation of new types of borylenes. These reactions not only serve as new methods for the synthesis of various stable borylenes, but also demonstrate that main-group-element compounds can mimic the behavior of transition-metal complexes.

Urban dust is an important medium of potential toxic metal (PTM) pollution that affects human health and the urban ecosystems. A total of 374 fugitive dust samples were collected in Nanjing, a fast-developing city in southern China, including six sub-types of dust (residential district, commercial district, industrial district, traffic district, cultural and educational district, green land). Chemical analysis of eighteen metal elements by inductively coupled plasma mass spectrometry was carried out to establish the sub-type sources profiles of fine particles for fugitive dust. The results show that these metals (Cu, Zn, Se, Sr, Mo, Cd, Sb, and Pb) are mainly from anthropogenic sources and present a high degree of pollution; Mn, As, and Ba are moderately affected by human activities and present a significant degree of pollution; Ni, Co, Cr, Tl, V, Be, and Ti mainly originate from natural sources and present significant, moderate and minimal degrees of pollution. For the dust types from different functional areas, the differences of enrichment factor (EF) values were relatively small. Metals were highly concentrated in dust from residential, cultural and educational district, which had high density population and would pose higher health risk. In all types of dust, the metals rich in crust (Ti, Mn, Ba, Sr) and the metals (Cu, Zn, Pb) closely connected with city activities were the main components. Factor analysis revealed that there were six main sources of metals in dust collected from Nanjing: industrial activity, building decoration, soil dust, metal smelting, traffic emissions, and brake abrasion. Generally, noncarcinogenic and carcinogenic health risks of metals found in dust are rarely found for children and adults based on health risk assessments. However, the noncarcinogenic risk of Pb in commercial districts for children should be noted because its hazard quotient was higher than the safety threshold level. For the accumulative health risk of eighteen metals, the noncarcinogenic risk values of dust from six functional areas for children were all over the threshold (1.0), whereas below 1.0 for adults. The difference between children and adults was relatively obvious. All accumulative risk values of carcinogenic metals did not exceed the carcinogenic risk threshold of 1 × 10−4, which suggested that no risk prevention measures were needed.

The catalytic conversion of ethanol into 1,3-butadiene has once again attracted widely attention. However, the kinetics of 1,3-butadiene synthesis from ethanol are rarely reported. In this work, the kinetics of 1,3-butadiene synthesis from ethanol and acetaldehyde over ZrO2-MgO-SiO2 catalyst developed by our research group were studied. The study was carried out in an isothermal integral reactor at temperatures of 573–613 K with various space velocity. The kinetics of two main side reactions, dehydration of ethanol to ethylene and ether, were also measured. It was assumed that the aldol condensation rate determining step followed the Langmuir-Hinshelwood mechanism and the Eley-Rideal mechanism respectively, from which the corresponding kinetics models were derived. The results showed that the aldol condensation step followed the Langmuir-Hinshelwood mechanism over ZrO2-MgO-SiO2 catalyst, and the activation energy was calculated to be 54.6 kJ/mol. The obtained kinetics models were verified under the conditions of different ethanol/acetaldehyde molar ratio. The discrepancy between calculated outlet flow rates of key components and the experimental values was within ± 16%, indicating the validity of the obtained kinetics models. The research results can provide some theoretical guidance for the reactor design of 1,3-butadiene synthesis from ethanol.

Reactions of silanes with transition-metal complexes are of interest because their relevance to Si–H bond activation, the structural properties of polyhydrides, and catalytic hydrosilylation reactions. This work presents the results derived from reactions of arylsilanes Ph2SiH2 and PhSiH3 with OsH3Cl(PPh3)3 (1). Reaction of 1 with 1 equiv or excess Ph2SiH2 affords OsH3(SiClPh2)(PPh3)3 (2) or OsH4(SiClPh2)(SiHPh2)(PPh3)2 (3), respectively. These silyl complexes are formed via the oxidative addition of Si–H bonds and H/Cl exchange via silylene intermediates. Similarly, reaction of 1 with excess PhSiH3 produced the analogous bis(silyl) complex OsH4(SiClHPh)(SiH2Ph)(PPh3)2 (4). The bis(silyl) complexes are dodecahedral tetrahydride complexes containing weak Si···H interactions. The complex 3 reacts with PPh3 and CH3CN to selectively eliminate Ph2SiH2. Computational studies show that the preference for reductive eliminations from 3 follows the order Ph2SiH2 > H2 > Ph2SiHCl > Ph2HSi-SiClPh2.

In recent years, with the increasing of wind power development, the demand for low voltage ride-through (LVRT) technology was proposed to ensure the safe and reliable operation of the power system. The key issue of LVRT strategy for doubly-fed induction generator (DFIG) varies according to the network synchronisation modes. Firstly, the existed LVRT technologies when DFIG is connected to AC network are surveyed. Then relevant literatures about LVRT are summarised and analysed in regard to power surplus of two-terminal system and DC voltage control of multi-terminal system, respectively, when the wind farm is integrated with VSC-high-voltage direct current (HVDC). In the end, the coordinated control strategy of multi-terminal VSC–HVDC system and LVRT technology for islanded system are prospected in this study.

This paper is devoted to the uniqueness problem on meromorphic functions whose differential polynomials share one nonzero finite constant. We improve some previous results and answer two open problems posed by Dyavanal.

Epidemiological studies have demonstrated that the general population’s exposure to bisphenol A (BPA) substitutes is ubiquitous. Bisphenol F (BPF), one of the main BPA substitutes, is increasingly replacing BPA in plastics for food and beverage applications. Accumulating evidence suggests that BPA exposure is associated with nonalcoholic fatty liver disease (NAFLD)-like changes. However, the potential effects of BPF on lipid homeostasis remain poorly understood. In the present study, an epidemiological analysis with LC-MS-MS revealed that the BPF concentrations in the serum of NAFLD patients were significantly higher than those in a control group. Supporting this result, using Oil Red O, BODIPY 493/503, LipidTox Deep Red staining and gas chromatography-time-of-flight mass spectrometry (TOF-MS) assays, we found that BPF exposure induced NAFLD-like changes, with obvious lipid droplet deposition, triglyceride (TG) and fatty acids increase in mouse livers. Meanwhile, lipid droplet deposition and TG increase induced by BPF were also observed in HepG2 cells, accompanied by autophagic flux blockade, including autophagosome accumulation and the decreased degradation of SQSTM1/p62. Using adenoviruses dual-reporter plasmid RFP-GFP-LC3, RFP-GFP-PLIN2 transfection, AO staining, and EGFR degradation assays, we demonstrated that BPF treatment impaired lysosomal degradative capacity, since BPF treatment obviously impaired lysosomal acidification, manifested as decreased lysosomal hydrolase cathepsin L (CTSL) and mature cathepsin D (CTSD) in HepG2 and mouse liver issues. Additionally, v-ATPase D, a multi-subunit enzyme that mediates acidification of eukaryotic intracellular organelles, significantly decreased after BPF exposure in both the vitro and in vivo studies. This study ascertained a novel mechanism involving dysfunctional of lysosomal degradative capacity induced by BPF, which contributes to lipophagic disorders and causes lipid droplet deposition. This work provides evidence that lysosomes may be a target organelle where BPF exerts its potential toxicity; therefore, novel intervention strategies targeting lysosome are promising for BPF-induced NAFLD-like changes.

Fabrication strategies for photo-responsive ion gels have attracted attention owing to their precise spatial and temporal control with predetermined responses to light stimuli. In this work, a reversible light-driven method was introduced to devise photo-responsive ion gels by harnessing coumarin-based building blocks under 365 nm irradiation. A series of random copolymers composed of N, N-dimethylacrylamide (DMA) and 7-(2′-methacryloyloxyethoxy)–4-methylcoumarin (MAOEMC), namely P(DMA-r-MAOEMC), were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization with sufficient molecular weight (≈100 kDa). The coumarin moieties in those polymers exhibited a reversible photo-induced dimerization and photocleavage behavior in 1-ethyl-3-methylimidazolium bis (trifluoromethylsufonyl) imide ([C2mim][NTf2]). Those polymers - ionic liquid system at high polymer concentration (20 wt%) under suitable wavelength UV light irradiation led to sol–gel transition, which could be functionalized as photo-healable material and photo-controlled adhesion agents. Notably, the photo-controlled adhesiveness was reversible and can be mediated from 1.2 MPa to 0.2 MPa. This work opens new avenues to develop multifunctional ion gels using dynamic covalent bonds.

A simple, sensitive and specific ultra performance liquid chromatography coupled to electrospray tandem high resolution mass spectrometry (UPLC-ESI-HRMS/MS) method has been developed and validated for quantification of paraquat in plasma and urine. The sample preparation was carried out by one-step protein precipitation with acetonitrile. The paraquat was separated with a HILIC column in 10min. Detection was performed using Q Exactive Orbitrap mass spectrometer by Targeted-MS/MS scan mode. Methodological parameters, such as ammonium formate concentration, formic acid concentration, spray voltage, capillary temperature, heater temperature and normalized collision energy were optimized to achieve the highest sensitivity. The calibration curve was linear over the concentration range of LOQ-1000ng/mL. LOD was 0.1 and 0.3ng/mL, LOQ was 0.3 and 0.8ng/mL for urine and plasma, respectively. The intra- and inter-day precisions were

Neuroactive metabolites in dopamine, serotonin and kynurenine metabolic pathways play key roles in several physiological processes and their imbalances have been implicated in the pathophysiology of a wide range of disorders. The association of these metabolites' alterations with various pathologies has raised interest in analytical methods for accurate quantification in biological fluids. However, simultaneous measurement of various neuroactive metabolites represents great challenges due to their trace level, high polarity and instability. In this study, an analytical method was developed and validated for accurately quantifying 12 neuroactive metabolites covering three metabolic pathways in youth urine by ultra performance liquid chromatography coupled to electrospray tandem high resolution mass spectrometry (UPLC-ESI-HRMS/MS). The strategy of dansyl chloride derivatization followed by solid phase extraction on C18 cartridges were employed to reduce matrix interference and improve the extraction efficiency. The reverse phase chromatographic separation was achieved with a gradient elution program in 20 min. The high resolution mass spectrometer (Q Exactive) was employed, with confirmation and quantification by Target-MS/MS scan mode. Youth urine samples collected from 100 healthy volunteers (Female:Male=1:1) were analyzed to explore the differences in metabolite profile and their turnover between genders. The results demonstrated that the UPLC-ESI-HRMS/MS method is sensitive and robust, suitable for monitoring a large panel of metabolites and for discovering new biomarkers in the medical fields.

A series of well-defined random copolymers comprising butyl acrylate (BA) and 4-phenylazophenylmethacrylate (AzoMA) (P(AzoMA-r-BA)) are prepared successfully by reversible addition fragmentation chain transfer (RAFT) polymerization. P(AzoMA-r-BA)s show LCST-type phase transition in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfone)amide ([C4mim][NTf2]). LCST depends on the photoisomerization state of azobenzene, as well as on the AzoMA composition in the random copolymers. LCST of (P(cis-AzoMA-r-BA) is significantly higher than that of P(trans-AzoMA-r-BA), because cis-AzoMA and trans-AzoMA behave as solvato-philic and solvato-phobic comonomer, respectively. At a bistable temperature, photo-induced phase separation is completely reversible. Secondly, based on this phenomenon, a thermo-/photo- responsive ion gel (BA-AzoMA ion gel) can be prepared by free radical polymerization of BA and AzoMA using ethylene glycol dimethacrylate (EGDMA) as crosslinker in [C4mim][NTf2]. BA-AzoMA ion gel shows high temperature contraction and low temperature expansion behavior, due to LCST-type phase behavior of polymer system consisting of AzoMA and BA. Contraction temperature of BA-AzoMA ion gel depends on photoisomerization state of the azobenzene group in polymers. At a bistable temperature, photo-induced expansion-contraction is reversible. Finally, a Photo-induced actuator can be realized using BA-AzoMA ion gel at suitable temperatures, featuring reversible bending by alternate irradiating with visible and UV light. The bending behavior is also demonstrated.

Resonances or instability phenomena may occur in wind farms integration through VSC-HVDC system. The impact on resonance characteristics from the wind speed, number of wind turbines at different locations and length of the connection line between wind farms and VSC-HVDC converter station is studied in this paper. First, the model of the interconnected system composed of VSC-HVDC and two wind farms each of which is represented by an aggregated DFIG is established. Then, the resonance risk of the interconnected system under the condition of different connection line length is revealed by means of impedance-based method and time domain simulation. Further, the variation of impedance-frequency characteristics caused by different wind speed and wind turbines number of wind farms at different locations is analyzed. Finally, the impact on resonance risk from a variety of external conditions in multiple wind farms is evaluated quantitatively using the frequency and damping of the resonant mode obtained by the aggregated RLC circuit approach. With the results of stability analysis, the suggestion for setting of converter control parameters in multiple wind farms connected to VSC-HVDC is presented.

The paper proposes an adaptive robust control to let mechanical systems to approximately follow the designed constraint with uncertainty. The uncertainty considered in the system is time-varying and bounded. It is bounded, but the exact bound is unknown. A novel leakage and dead-zone type adaptive law is constructed, which emulates a parameter vector relevant to the uncertainty bound. With the adaptive parameter, the robust control can guarantee the system performance as uniform boundedness and uniform ultimate boundedness regardless of the uncertainty through the theoretically and the illustration of an example.

A method for the identification and quantification of bisphenol A and 12 bisphenol analogues in river water and sediment samples combining liquid-liquid extraction, precolumn derivatization, and ultra high-performance liquid chromatography coupled with tandem mass spectrometry was developed and validated. Analytes were extracted from the river water sample using a liquid-liquid extraction method. Dansyl chloride was selected as a derivatization reagent. Derivatization reaction conditions affecting production of the dansyl derivatives were tested and optimized. All the derivatized target compounds were well separated and eluted in 10 min. Dansyl chloride labeled compounds were analyzed using a high-resolution mass spectrometer with electrospray ionization in the positive mode, and the results were confirmed and quantified in the parallel reaction monitoring mode. The method validation results showed a satisfactory level of sensitivity. Linearity was assessed using matrix-matched standard calibration, and good correlation coefficients were obtained. The limits of quantification for the analytes ranged from 0.005 to 0.02 ng/mL in river water and from 0.15 to 0.80 ng/g in sediment. Good reproducibility of the method in terms of intra- and interday precision was achieved, yielding relative standard deviations of less than 10.1 and 11.6%, respectively. Finally, this method was successfully applied to the analysis of real samples.

Excessive metal exposure has been recognized as one of the detrimental factors for brain damage. However, the potential adverse effects induced by heavy metals on monoamine neurotransmitter pathways remains poorly understood. Our study aimed to investigate the possible association between metal exposure and neurotransmitter metabolism. By a cross-sectional investigation, 224 electroplating workers and 213 non-electroplating exposure workers were recruited in the exposure and control groups. Metal exposure levels were analyzed using inductively-coupled plasma mass spectrometry and monoamine neurotransmitter pathway metabolites were measured by ultra-performance liquid chromatography tandem mass spectrometry in human urine samples. Multivariate linear regression model was used to assess the dose-response relationships of urinary metals and neurotransmitter pathway metabolites. Significant dose-dependent trends of urinary vanadium quartiles with all metabolites were observed, and the trends demonstrated significance after multiple testing correction. It also showed that urinary chromium levels were significantly associated with decreased serotonin level and cadmium was positively associated with norepinephrine and epinephrine. In addition, arsenic was positively associated with tryptophan, serotonin, dopamine and norepinephrine. Iron was positively associated with increased homovanillic acid (HVA) and epinephrine while nickel was negatively associated with increased epinephrine levels. Zinc was positively related to tryptophan, kynurenin (KYN), 5-hydroxyindole acetic acid (5-HIAA), dopamine, HVA and norepinephrine. There was no significant association between urinary copper with any other metabolites after adjusting of multiple metal models. Metal exposure may be associated with neurotransmitter metabolism disturbances. The present work is expected to provide some support in the prevention and management of metal-associated neurological diseases.

Wireless Capsule Endoscope (WCE) enables developing actively controlled capsule for potential complex surgeries, imaging, and new medicine tests. These tasks of WCE need safe, efficient, and precise 3D localization techniques. In this paper, a new application of the magnetic resonance coupling (MRC) technique, which has been widely developed for efficient wireless power transfer, is introduced. It is proposed that the distance dependent signal strength in a MRC system can be beneficially used for 3D localization. The new 3D-MRC localization system consists of three orthogonal emitting coils which are powered by a battery in the capsule, and three pairs of orthogonal receiving coils which are placed outside human body. The distances between the WCE and the receiving coils can be estimated with good accuracy by studying the signal strengths in individual receiving coils. The proposed new 3D-MRC localization system also exhibits higher efficiency when compared with traditional magnetic induction method for 3D localization due to the use of MRC.

Highly ordered mesoporous Co3O4 materials have been prepared via a nanocasting route with three-dimensional KIT-6 and two-dimensional SBA-15 ordered mesoporous silicas as templates and Co(NO3)2 · 6H2O as precursor. Through changing the hydrothermal treating temperature of the silica template, ordered mesoporous Co3O4 materials with hierarchical structures have been developed. The larger pores around 10 nm provide an efficient transport for Li ions, while the smaller pores between 3–5 nm offer large electrochemically active areas. Electrochemical impedance analysis proves that the hierarchical structure contributes to a lower charge transfer resistance in the mesoporous Co3O4 electrode than the mono-sized structure. High reversible capacities around 1141 mAh g−1 of the hierarchically mesoporous Co3O4 materials are obtained, implying their potential applications for high performance Li-ion batteries.

Over the past couple of decades, Global positioning system (GPS) technology has been utilized to collect large-scale data from travel surveys. As the precise spatiotemporal characteristics of travel could be provided by GPS devices, the issues of traditional travel survey, such as misreporting and non-response, could be addressed. Considering the defects of dedicated GPS devices (e.g., need much money to buy devices, forget to take devices to collect data, limit the simple size because of the number of devices, etc.), and the phenomenon that the smartphone is becoming one of necessities of life, there is a great chance for the smartphone to replace dedicated GPS devices. Although, several general reviews have been done about smartphone-based GPS travel survey in the literature review section in some articles, a systematic review from smartphone-based GPS data collection to travel mode detection has none. The included studies were searched from six databases. The purpose of this review is to critically assess the current literature on the existing methodologies of travel mode detection based on GPS raw data collected by smartphones. Meanwhile, according to the systematic comparison among different methods from data-preprocessing to travel mode detection, this paper could carefully provide the Strengths and Weaknesses of existing methods. Furthermore, it is the crucial step to develop the methodologies and applications of GPS raw data collected by smartphones.