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Embedding heteroatoms into the main backbones of polymeric materials has become an efficient tool for tailoring their structures and improving their properties. However, owing to comparatively harsh heteroatom‐doping conditions, this has rarely been explored in covalent organic frameworks (COFs). Herein, upon aldol condensation of a trimethyl‐substituted pyrylium salt with a tritopic aromatic aldehyde, a two‐dimensional oxonium‐embedded COF with vinylene linkages was achieved, which was further converted to a neutral pyridine‐cored COF by in situ replacement of oxonium ions with nitrogen atoms under ammonia treatment. The two heteroatom‐embedded COFs are conceptually isoelectronic with each other, featuring similar geometric structures but different electronic structures, rendering them capable of catalyzing the visible‐light‐promoted multi‐component synthesis of tri‐substituted pyridine derivatives with good recyclability. [ABSTRACT FROM AUTHOR]

The effects of injecting TiO2 to a Li2O–MgO–ZnO–B2O3–SiO2 (LMZBS) microwave dielectric composite on sinterability, microstructure, crystalline phase, dielectric characteristics, mechanical characteristics, and coefficient of thermal expansion (CTE) were investigated. With the increase of TiO2 content, the main crystal orientation of the samples gradually changed from Li2MgSiO4 phase, Mg3B2O6 phase, and Mg2SiO4 phase to Li5.48Mg0.74Ti7.26O18, ZnTiO3 phase, and Mg2B2O5 and the densification temperature decreased, whisker-like crystal grains gradually increased, and the porous microstructure appeared at 15% TiO2. With the increase of TiO2 content, the densification temperature of LMZBS ceramics increases, and the dielectric constant increases with the increase of densification temperature. The CTE value decreases with the increase of titanium dioxide content, and the bending strength increases first and then decreases with the increase of titanium dioxide content. The composite with 10 wt% TiO2 content sintered at 900 °C exhibits superior performance: ε r of 7.97, Q value of 1305 (10 GHz), flexural strength of 259 MPa, CTE value of 10.2 ppm/°C, and τ f value of − 13 ppm/°C. The LMZBS/TiO2 composites are suitable for LTCC application with match-well Ag electrodes. [ABSTRACT FROM AUTHOR]

Five previously undescribed flavonoids (1–5) and ten known ones (6–15) were isolated from the roots of Oxybaphus himalaicus. Their structures were elucidated by spectroscopic experiments including NMR, HRESIMS and ECD. The cytotoxic activities of all isolated compounds were assayed against human lung carcinoma A549 cells and human hepatocellular carcinoma HepG2 cells in vitro. Compound 11 displayed the most powerful inhibitory effect with IC50 values of 19.47 ± 0.28 μM against A549 and 52.6 ± 0.38 μM against HepG2, respectively. [ABSTRACT FROM AUTHOR]

Two new cycloartane glycosides, cycloatriosides A and B (1–2), and a new oleanolic acid glycoside, thaliatrioside A (3), along with 7 known triterpenoids (4–10) were isolated from Thalictrum atriplex. The structures of the new compounds were established as 3-O-β-D-galactopyranosyl (20S, 24 R)-3β,16β,25,29-tetrahydroxy-20,24-epoxycycloartane-29-O-β-D-glucopyranoside (1), 3-O-β-D-glucopyranosyl-(1→2)-α-arabinopyranosyl-3β,22ξ,30-trihydroxycycloart-24-en-21-oic acid α-L-arabinopyranosyl-(1→6)-β-D-glucopyranoside (2) and 3-O-[α-L-rhamnopyranosyl-(1→3)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl]-oleanolic acid 28-O-β-D-glucopyranosyl ester (3) on the basis of extensive NMR and HR-ESI-MS analyses, along with acid hydrolysis. Their cytotoxic activities against human lung cancer cells A549 and human breast cancer cells MDA-MB-231 were evaluated using MTT method. Compound 9 showed cytotoxicity against MDA-MB-231 cell line with the IC50 value of 72.53 ± 1.08 μM. [ABSTRACT FROM AUTHOR]

The alumina/hexagonal boron nitride/glass fibers cloth/Polytetrafluoroethylene (Al2O3–hBN/GFs/PTFE) composites were prepared by blending-impregnation followed by hot compression method, and the dielectric, thermal properties of the composites with various hBN fillers content (0–20 wt.%) were investigated. The results show that the thermal conductivity of the composites increase significantly, while the coefficient of thermal expansion (CTE) decrease gradually, with the hBN content increasing. Composite substrates with 20 wt.% hBN exhibited high thermal conductivity as 1.05 W m−1 K−1, which is 5.3 times that of pure PTFE. Such compositions may be a promising material in high thermal conductivity copper clad laminate. [ABSTRACT FROM AUTHOR]

In order to improve the thermal properties of polytetrafluoroethylene (PTFE) as a high-frequency microwave dielectric substrate, PTFE/glass fiber (GF) composites filled with Si3N4 were prepared by the method of combining cold pressing and normal pressure sintering. The effects of content of Si3N4 on microstructure, thermal and dielectric properties of the PTFE/GF composites were studied by scanning electron microscope, laser thermal conductivity analyzer, thermal dilatometer and impedance analyzer, respectively. The results showed that silane coupling agent (KH550) could improve the dispersibility of the Si3N4 particles in PTFE to some extent and Si3N4 fillers could significantly improve the thermal properties of PTFE. Compared with pure PTFE, the coefficient of thermal expansion of PTFE/GF composite filled with 45wt% Si3N4 decreased from 109 to 27 ppm/°C and the thermal conductivity increased nearly twice. The dielectric constant of PTFE/GF composites grew with the content of Si3N4 and had good frequency stability. Although the dielectric loss of the composites deteriorated with the addition of Si3N4, it was significantly decreased with increasing frequency, indicating that there is a potential application of Si3N4 filled PTFE/GF composites in the field of high-frequency dielectric substrate. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur batteries possess great prospects in next‐generation energy‐storage devices though there are still some tough challenges currently. In this paper, MnO‐inlaid hierarchically porous carbon hybrid is prepared by a one‐pot solid‐state method and followed with annealing treatment. The MnO nanoparticles are synthesized via glucose‐derived carbon reduction with salt as the template. The resultant carbon‐coated MnO, which owns a hierarchical porous structure, benefits to alleviate the shuttle effect of lithium‐sulfur battery and immobilize the soluble polysulfide to improve the electrochemical performance by both physical limitation and chemisorption. As a result, the cathode MnO‐PC/S reveals a high initial discharge capacity of 1384 mAh g−1 at 0.2 C and a high retention capacity of 593 mAh g−1 over 200 cycles. [ABSTRACT FROM AUTHOR]

Herein, the Li2O–MgO–ZnO–B2O3–SiO2 (LMZBS) ceramic with low sintering temperatures were prepared via the traditional solid-state method, and the Mg2SiO4/LMZBS ceramic composite was prepared by adding Mg2SiO4 ceramic, and the results showed that the properties of LMZBS ceramic was improved upon addition of Mg2SiO4 ceramic. The sinterability, microstructure, dielectric properties, mechanical properties and coefficient of thermal expansion (CTE) of composite were determined. The crystal structure was determined using X-ray diffraction, and Mg2SiO4, Mg3B2O6, Mg2B2O5 were the main phase. The 20 wt% Mg2SiO4 ceramic sintered at 900 °C exhibited superior performance: ε r of 6.97, Q value of 1732 at 10 GHz and flexural strength of 206 MPa, and CTE value of 10.06 ppm/°C. The composite was also found to match well with the Ag electrode in an investigational study. These properties have made the Mg2SiO4/LMZBS ceramic composite great candidates in low-temperature co-fired ceramics technology. [ABSTRACT FROM AUTHOR]

In this study, CaO–Al2O3–B2O3–SiO2(CABS) glass/MgAl2O4 composite for low-temperature co-fired ceramics (LTCC) applications was prepared. The sinterability, microstructure, dielectric properties, mechanical properties, and coefficient of thermal expansion (CTE) of composite were determined. MgAl2O4 as ceramic filler improves the dielectric properties of the composite, mechanical properties, and density. The 45 wt% CABS glass contents composite sintered at 900 °C exhibit superior performance, which have relatively high bulk density, dielectric constant = 6.51, dielectric loss = 3.1 × 10–3 (10 GHz) and CTE = 4.51 ppm/°C, flexural strength = 261 MPa. [ABSTRACT FROM AUTHOR]

ZIF-derived carbon structures are considered as desired electrode materials for supercapacitors due to their high surface area, high conductivity, and porous structure. However, the most reported ratio of 2-methylimidazole and Zn(II) is 4:1 to 20:1, which limits commercial applications due to the increasing cost. In this paper, a multirole Zn(II)-assisted method is presented from Zn(II) solution, ZnO, ZnO/ZIF-8 core-shell nanostructure, to 3D hierarchical micro-meso-macroporous carbon structures with a 1:1 ratio of 2-methylimidazole and Zn(II). The hierarchically porous carbon has a high surface area of 1800 m2 g−1 due to the synergistic effect of multirole Zn(II). The unique carbon-based half-cell delivers the specific capacitances of 377 and 221 F g−1 at the current densities of 1.0 and 50 A g−1, respectively. As a 2.5 V symmetrical supercapacitor, the device reveals a high double-layer capacitance of 24.4 F g−1, a power density of 62.5 kW kg−1, and more than 85.8% capacitance can be retained over 10000 cycles at 10 A g−1. More importantly, the low-cost hierarchically porous carbon could be easily produced on a large scale and almost all chemicals can be reused in the sustainable method. [ABSTRACT FROM AUTHOR]

The 40Bi2O3-30B2O3-(30−x)ZnO-xSrO (x=0–15mol%, BBZSr) glass system was prepared by the conventional melt quenching method. The effect of SrO addition on structure, thermal properties, chemical stability and sealing performance of BBZSr glass were investigated thoroughly. The experimental results show that the total proportions of [BO3] group and [BO4] group decrease and the vibrations of [BiO3] group and [BiO6] group become weaker with the increase of SrO addition content, suggesting the glass network structure is strengthened owing to the SrO addition. Hence, both the thermal and chemical stability were significantly improved as the SrO content was increased. When the SrO content increased from 0 to 15mol%, the glass transition temperature and softening temperature slightly increased from 380 to 388 °C and from 392.7 to 402.2 °C, respectively, meanwhile the coefficient of thermal expansion also increased from 10.49×10−6 to 11.16× 10−6/°C (30–300 °C). The BBZSr glass with 15mol% SrO exhibited excellent comprehensive properties with low glass transition temperature(384.9 °C), low softening temperature(400.3 °C), high coefficient of thermal expansion (11.14×10−6 C, 30–300 °C), good thermal and chemical stability. Besides, the glass had the good wetting behavior and sealing performance for Al-50%Si alloy. [ABSTRACT FROM AUTHOR]

The anterior cingulate cortex (ACC) serves as a critical hub for the anxiety and pain perception. The large-conductance Ca2+-activated potassium channels, or BKCa channels, are ubiquitously expressed throughout the central nervous system including the cingulate cortex. However, what changes of cortical BKCa channels undergo in the ACC remains unknown in pain-related anxiety. In the present study, a significant upregulation of synaptic and non-synaptic BKCa channel accessory β4 subunits in the ACC was accompanied with pain-associated anxiety-like behaviors in the chronic compression of multiple dorsal root ganglia (mCCD) of the rat. NS1619, an opener of BKCa channels, significantly rescued the alteration of fAHP and AP duration of ACC pyramidal neurons in mCCD rats. The mRNA expression of BKCa β4 subunits was extremely upregulated in the ACC after mCCD with the increased amount of both synaptic and non-synaptic BKCa β4 subunit protein. Meanwhile, NS1619 reversed the enhanced AMPA receptor-mediated spontaneous excitatory postsynaptic current (sEPSC) frequency and the attenuated PPR of ACC neurons in mCCD rats. Local activation of BKCa channels in the ACC reversed mechanical allodynia and anxiety-like behaviors. These results suggest that the upregulation of postsynaptic and presynaptic BKCa β4 subunit may contribute to neuronal hyperexcitability and the enhanced synaptic transmission in the ACC in neuropathic pain state, and then may result in anxiety-like behavior induced by neuropathic pain. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of Cl−/SO42− molar ratios and hydrolysis temperature on the hydrolysis process and TiO2 pigment, H2TiO3 was prepared with a low concentration of titanyl sulfuric–chloric acid solution by hydrothermal hydrolysis. Under the optimal hydrolysis conditions, 1.5–2.2 μm of H2TiO3 samples were achieved. After doping and calcination, anatase TiO2 pigments demonstrated excellent performance: the achromic ability of tinctorial strength (TCS) and blue phase index (SCX) were 1,429 and 4.07, respectively. As hydrolysis was a significant step in the process, the structure was simplified to a periodic structure of Ti[OH](H2O)3Cl(SO4) to simulate the cluster structures. Based on experimental results and density functional theory (DFT) calculation, the hydrolysis mechanism was presumed to be a process of anionic (OH−, Cl− and SO42−) competition reaction to explain the formation of anatase‐type H2TiO3, and the crystal growth direction of H2TiO3 was also confirmed to be a (OA) and b (OB). [ABSTRACT FROM AUTHOR]

In present work, the microwave dielectric properties of CaTiO3-added Li2Zn3Ti4O12 ceramics prepared by the conventional solid-state method have been investigated. The phase composition, microstructure and microwave dielectric properties of (1 − x) Li2Zn3Ti4O12–x CaTiO3 (x = 3, 4, 5, 6 and 7 wt%) ceramics were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), EDS and network analyzer. The XRD and EDS results indicated that the ceramics involved Li2Zn3Ti4O12 and CaTiO3 phases. The SEM micrographs shown that as the CaTiO3 contents increased, the average grain size of the composition ceramics decreased. The microwave dielectric properties of the composition ceramics can be effectively controlled by varying the CaTiO3 contents. The values of dielectric constant (εr) and τf of the composition ceramics were increased, and the quality factor (Q × f) was decreased with increasing the CaTiO3 contents. Typically, a new temperature stable microwave dielectric material of 0.94 Li2Zn3Ti4O12–0.06 CaTiO3 with excellent microwave dielectric properties of εr = 21.7, Q × f = 61,490 GHz, and τf = + 2.68 ppm/°C was attained when sintered at 1175 °C for 4 h. [ABSTRACT FROM AUTHOR]