Search

In this work, the corrosion behaviors of as-plasma sprayed Yb 2 SiO 5 and LaMgAl 11 O 19 coatings under an environment with a volumetric ratio of 90% H 2 O-10% O 2 were investigated at 1300 °C. The results showed that Yb 2 SiO 5 and LaMgAl 11 O 19 coatings had good water vapor corrosion resistance. Therefore, Si/Yb 2 SiO 5 /LaMgAl 11 O 19 tri-layer EBCs were designed and prepared to completely cover the surface of SiC f /SiC by using atmospheric plasma spraying (APS). The water vapor corrosion behaviors of SiC f /SiC with and without EBCs at 1300 °C were investigated. The results showed that tri-layer coating can provide better corrosion resistance for SiC f /SiC at a high-temperature steam environment at 1300 °C. By comparing the water vapor corrosion behaviors of single-layer coatings and the tri-layer EBCs under same corrosion environment, it was found that the thermal mismatch stress and the formation of TGO is the main causes of tri-layer coating failure. [ABSTRACT FROM AUTHOR]

The synthesis of mono-nuclear β-pyridylenolate zinc complexes L 1 2 Zn ( 1 ) (L 1 = (2-C 5 H 4 N)–CH=C(CH 3 )–O–) and L 2 2 Zn ( 2 ) (L 2 = (2-C 5 H 4 N)–CH=C (2-CH 3 C 6 H 5 )–O–) were performed by the protonolysis of the corresponding β-pyridylenol bidentate ligands 1-(2-pyridinyl)-2-propanone (L 1 H) and 1-(2-methylphenyl)-2-(2-pyridinyl)-ethanone (L 2 H) with diethylzinc in a 2:1 M ratio, respectively. The unanticipated tetra-nuclear β-pyridylenolate zinc complex [L 1 2 Zn- μ -O (Et)ZnEt] 2 ( 3 ) was isolated by the reaction of L 1 H with an equiv. of ZnEt 2 and oxygenation with air. All the complexes were well characterized by single crystal X-ray crystallography. Complexes 1 – 3 were tested as an initiator for the ring opening polymerization (ROP) of ε-caprolactone and l -lactide. In the same conditions, 1 and 2 are shown inefficient for ROP due to the lack of suitable initiating group for polymerization, however, tetra-nuclear complex 3 is a highly active single-component initiator in the ROP of ε-caprolactone and l -lactide. Complex 3 was also researched for its catalytic activity in block (PCL- b -PLLA) and gradient (LA- grad -CL) copolymerization of ε-caprolactone and l -lactide. [ABSTRACT FROM AUTHOR]

This work investigated the reactivity of 2-benzylpyridyl lithium (2-Pyr)C(Ph)(R)Li (R = SiMe 3 , Li1 ; R = H, Li2 ) toward benzonitrile derivatives. Based on the different products, the reaction between lithium salts and nitriles might involve in addition, elimination and bimolecular coupling pathways, respectively. Treatment of Li1 with ArCN (Ar = Ph, p -Tolyl, o -Tolyl, p -OMePh) yielded an addition intermediate pyridyl-1-aza-allyl-lithium [{(2-Pyr)C(Ph)C(Ar)N(SiMe 3 )}Li] 2 ( 1, Ar = Ph) and its corresponding hydrolysis product 2-benzylpyridyl-ketone 2 – 5 , respectively, in which the reaction involved in a 1,3-shift of -SiMe 3 group to form a dimeric pyridyl-1-aza-allyl-lithium then followed by acidic hydrolysis. The MeOLi elimination reaction between Li2 and p -MeO(C 6 H 4 )CN resulted in formation of 4-(2-benzylpyridyl)benzonitrile 6 . The reaction of Li2 with p -Me(C 6 H 4 )CN in the presence of TMEDA generated a 1:2 hydrolysis adduct 2-benzylpyridyl-enaminone 7 , however, in the absence of TMEDA it afforded a coupling product of bimolecular nitriles, 1-(4-methylphenyl)-2-cyanophenyl-ethanone 8 . We speculated the reaction mechanisms in sequence. The crystal structures of 1 and 5 – 8 were analyzed. [ABSTRACT FROM AUTHOR]

The cyclic oxidation behavior of two high-Mo containing Ni-based single crystal superalloys with different Al contents at 1100 °C has been investigated. The higher formation tendency of the continuous and dense α-Al 2 O 3 scales in the alloy with higher Al content can prevent the volatilization of MoO 3 through decreasing the diffusion of Mo. Besides the spallation of oxide scales, the volatilization of refractory metal oxides can also result in the mass loss of the samples in the cyclic oxidation tests, especially in the Ni-based single crystal superalloys with high contents of refractory elements and weak formation tendency of continuous α-Al 2 O 3 scales. [ABSTRACT FROM AUTHOR]

The stress and orientational dependence of the oxidation-induced dynamic recrystallization of a Ni-based single crystal superalloy during high temperature creep were investigated. Cellular recrystallization appeared on the surface of the sample because of the oxidation-induced γ′-free layer. With the increase of the stresses, the depths of the recrystallized layers increased at first and then decreased. Besides, the tendency of recrystallization in <011> orientation was stronger than that in <010> orientation under the same load. The underlying mechanisms are discussed in this study. [ABSTRACT FROM AUTHOR]

Four new azaallylamino metallic complexes have been prepared. The insertion reactions of Li{CH[SiN(Me 2 )Me 2 ] 2 }( 1 ) with Bu t CN or PhCN generated azaallyla-mino-lithium Li{[N(Me 2 )Si(Me 2 )C(H)C(Bu t )]N[Si(Me 2 )N(Me 2 )]·Bu t CN} ( 2 ) or 1,3- diazaallylamino-lithium Li{[N(Me 2 )Si(Me 2 )C(H)C(Ph))]N[C(Ph)NSi(Me 2 )N(Me 2 )]} ( 3 ), respectively. Further transmetalation reaction of 2 with ZrCl 4 afforded complex Cl 3 Zr{[N(Me 2 )Si(Me 2 )C(H)C(Bu t )]N[Si(Me 2 )N(Me 2 )]}( 4 ), and 3 with SnCl 4 yielded Cl 3 Sn{[N(Me 2 )Si(Me 2 )C(H)C(Ph)]N[C(Ph)N(Si(Cl)(Me 2 ))]} (5) . The crystal structures of 2 , 4 and 5 were reported. Their formation involved 1,3- and 1,5-shift of the bulky silyl group [-Si(NMe 2 )Me 2 ]. A mechanism of the halogenation reaction is proposed based on the structural parameters of 5 . [ABSTRACT FROM AUTHOR]

In this work, self-crosslinked sulfonated polyether etherketone membrane (C-SPEEK) was synthesized by Friedel-Crafts alkylation at 130 °C with chloromethylated sulfonated polyether etherketone (SPEEK-Cl). The water uptake (WU) of the C-SPEEK was 47.75% with a 8.69% swelling rate (SR) at 60 °C, compared with the sulfonated polyether etherketone membrane (SPEEK) with WU of 110.60% and SR of 57.99%. The contradiction between dimensional stability and proton conductivity under high sulfonation degree was overcome. The self-crosslinking composite membranes were prepared by doping with carbon nanomaterials (Graphite oxide, GO; reduced graphene oxide, rGO and carbon nanotubes, CNTs) and phosphotungstic acid (HPW). Since HPW and carbon nanomaterials incorporated in membrane facilitate protons conduction via both Grotthuss and Vehicle mechanisms, the hybrid membranes demonstrated the improved conductivities. At 80 °C, C-SPEEK/HPW/GO showed proton conductivity as high as 119.04 mS/cm, which was 2.4 folds higher than that of the C-SPEEK. Furthermore, the superior performance of C-SPEEK/HPW/GO was further validated through H 2 /O 2 single cell test. The C-SPEEK/HPW/GO produced a higher power output of 876.80 mW/cm2, whereas only 776.72 mW/cm2 for C-SPEEK was recorded. Thus, C-SPEEK/HPW/GO and C-SPEEK may be promising membrane materials for potential applications in fuel cells. Image 1 • Crosslinked SPEEK membrane was synthesized by Friedel-Crafts alkylation. • C-SPEEK doped 2D layered GO exhibited better performance than 2D CNTs. • C-SPEEK/HPW/GO exhibited high power density in Fuel Cell Performances. [ABSTRACT FROM AUTHOR]

• A series of β-pyridyl-enamino aluminum complexes were synthesized and used as catalysts for the ROP of ε-CL and δ-VL. • The electronic and steric effects of the complexes were investigated on the ROP of ε-CL and δ-VL by kinetic studies. • The rate-determined step in ε-CL and δ-VL polymerization depends on their different insertion rate in the propagation. This contribution illustrates the significant influence of the Al-catalyzed ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) ring-opening polymerizations. A series of β-pyridyl-enamino aluminum complexes [AlLMe 2 ] 1–6 {L = [(2-C 5 H 4 N)-C(H) C(Ph) N(Ar) ], Ar = C 6 H 5 (1), 2,6-Me 2 C 6 H 3 (2), 2,6-Et 2 C 6 H 3 (3), 2,6- i Pr 2 C 6 H 3 (4), 4-FC 6 H 4 (5), C 6 F 5 (6)} were synthesized and characterized by NMR spectroscopy and single-crystal X-ray diffraction. The catalytic activities the polymerization of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) correlated with the substituent's character of the ortho and para groups on the Ar moieties of the β-pyridyl-enamino ligands. For the polymerizations of the both cyclic esters, complexes 1 , 5 and 6 displayed excellent catalytic activities in the presence of the initiator benzyl alcohol, while complexes 2 – 4 exhibited much lower activities under the same conditions. Kinetic studies revealed that complex 5 polymerized ε-CL at a faster rate in comparison to 1 and 6 , where highlighted a cumulative effect of both the electronic and steric effect on the ligands. By contrast, for the ROP of δ-VL, complex 1 was found to be more active than the catalysts 5 and 6. This unusual result was suggested the rate-determined step was the "insertion" step in ε-CL and δ-VL polymerization, the former's insertion rate is faster than the latter's. [ABSTRACT FROM AUTHOR]

The bismuth layer-structured Na 0.5 Bi 4.5- x Pr x Ti 4 O 15 ( x  = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) (NBT- x Pr 3+ ) ceramics were fabricated using the traditional solid reaction process. The effect of different Pr 3+ contents on dielectric, ferroelectric and piezoelectric properties of Na 0.5 Bi 4.5 Ti 4 O 15 ceramics were investigated. The grain size of Pr 3+ -doping ceramics was found to be smaller than that of pure one, the maximum dielectric constant and Curie temperature T c gradually decreased with increasing Pr 3+ contents, and the dielectric loss decreased at high temperature by Pr 3+ -doping. Moreover, the activation energy ( E a ), resistivity ( Z’ ), remanent polarization (2 P r ) and piezoelectric constant ( d 33 ) increased by Pr 3+ -doping. The NBT- x Pr 3+ ceramics with x  = 0.3 achieved the optimal properties with the maximum dielectric constant of 1109.18, minimum loss of 0.00822 (250 kHz), E a of 1.122 eV, Z’ of 7.9 kΩ cm (725 ºC), d 33 of 18 pC/N, 2 P r of 12.04 μC/cm 2 . The enhancement was due to the addition of Pr 3+ which suppressed the decreasing of resistivity at high temperature and made it possible for NBT- x Pr 3+ ceramics to be poled in perpendicular direction, implying that it is a great improvement for Na 0.5 Bi 4.5 Ti 4 O 15 ceramics in electrical properties. [ABSTRACT FROM AUTHOR]

New lead-free dielectric ceramics, Na 1+x BiTi 6 O 14+0.5x (x = −0.02, − 0.01, 0.01, 0.02), were prepared by the conventional solid-state method. Micro-structural and electrical properties of Na 1+x BiTi 6 O 14+0.5x were studied. XRD showed all the samples exhibited a single structured phase. Grains decreased at the beginning, then grew with the increasing x content in SEM. Impedance spectra (IS) analysis evidenced the phenomena that the dielectric permittivity increased firstly, then decreased, while the loss had the opposite trend. Z* plots showed that Na 1+x BiTi 6 O 14+0.5x ceramics were a kind of dielectrics. The activation energy ( E a ) could be calculated in the range of 1.53–1.65 eV, which indicated they were dielectric ceramics. Na 1+x BiTi 6 O 14+0.5x ceramics (x = 0.01) sintered at 1040 °C showed prominent dielectric properties with a dielectric constant of 25.76, loss of 0.07%, E a of 1.65 eV, density of 3.463 g/cm 3 , impedance of 0.532 MΩ cm, -Z′′ max of 0.1958 MΩ cm, capacitance of 5.56 pF/cm (600 ℃), which were enhanced much compared with other samples. The existence of dielectric properties with high dielectric constant, low dielectric loss and wide operating temperature range makes it possible to develop the ceramics into high-temperature capacitors. [ABSTRACT FROM AUTHOR]

Silicon (Si)-based materials show attractive potentials as the anode for lithium-ion batteries (LIBs) due to their high theoretical specific capacity. For the conventional silicon/reduced graphene oxide (Si/rGO) composites, the electrical conductivity, C/O ratio, and defect structure of reduced graphene oxide (rGO) significantly impact their electrochemical properties. Herein, we use three methods to prepare graphite oxide (GO) to adjust the percentage of functional groups, which further enhance the physicochemical properties of rGO and thus improve the electrochemical properties of Si/rGO. The GOs were synthesized through Hummers method (labeled as GO-1), Hummers method with H 2 O modulation (labeled as GO-2), and Hummers method with H 2 O and H 3 BO 3 modulation (labeled as GO-3). Due the H 2 O promotes the production of hydroxyl and epoxy groups, and H 3 BO 3 forms complexes with hydroxyl groups,the ratio of hydroxyl and epoxy groups in GO-1 to GO-3 is increased. After reduction process, the reduced rGO-3 exhibits a high C/O ratio, large structural defects, and excellent electrical conductivity. Because of the excellent properties of rGO-3, as an electrode material, Si/rGO-3 exhibits excellent electrochemical performance, with the highest reversible capacity of about 780.8 mAh/g after 150 cycles at 1 A/g and a good rate performance of 657.0 mAh/g at 5 A/g. This work proves that modulation of rGO from the GO with different oxygen-containing functional groups lead to enhanced ionic conductivity, cyclic stability, and rate capability of the Si/rGO electrodes. [Display omitted] • A series of silicon/reduced graphene oxide (Si/rGO) was fabricated with different graphene oxide (GO). • Larger defects, and better electrical conductivity of rGO-3 promote the electrochemical performance of Si/rGO-3. • Si/ rGO-3 achieves high initial coulombic efficiency and excellent cycling performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Field-induced electron emission offers the best performance point electron source for electron microscopes. Herewith we report a new cold field-emission point electron source utilizing a nanoneedle made of lanthanum hexaboride (LaB 6) and its implementation in a spherical aberration-corrected transmission electron microscope (TEM). A sub-ångstrom resolution of 0.96 Å has been obtained with the TEM operated at an acceleration voltage of 60 kV and a smaller energy spread was also observed compared with the contemporary W(310) electron source. In particular, the LaB 6 nanoneedle cold field-emission electron source required no thermal flashing for continuous operation of extended hours (>100 hours) while exhibiting and sustaining a high stability in emission current (<1%). We attribute the excellent performance of the LaB 6 nanoneedle electron source to (i) a low work function of LaB 6 ; (ii) excellent alignment of the nanoneedle emitter by the electron and ion dual-beam processing with nanoscale precision and (iii) robustness of the nanometric structure that suppressed mechanical vibrations of the LaB 6 emitter even in a high electric field. This new LaB 6 nanoneedle cold field-emission electron source enables stable high-resolution imaging in TEM and it will also benefit cryogenic electron microscopy, scanning electron microscopy, electron beam lithography, and other electron beam technologies. [ABSTRACT FROM AUTHOR]

Atmospheric plasma spraying (APS) was used to prepare three-layer environmental barrier coatings (EBCs) Si/Yb 2 SiO 5 /LaMgAl 11 O 19 (LMA) on a SiC f /SiC substrate. Isothermal aging test of the specimens were performed between 1000 and 1360 °C for 500 h. The flexural strength of the specimens after isothermal aging was investigated. Microcracks and holes were observed in the as-sprayed EBCs because of the shock cooling during the APS process, but reduced after isothermal aging, and the EBCs became denser. At least 80.07% of the flexural strength of the SiC f /SiC substrate with EBCs was maintained after isothermal aging, but only 35.91% strength was maintained without EBCs. In particular, the retention ratio of flexural strength was 90.72% after isothermal aging at 1360 °C, despite a reaction between the layers of the EBCs. All the specimens with EBCs showed "pseudo-plastic" fracture, compared with the brittle fracture of specimens without EBCs. [ABSTRACT FROM AUTHOR]

LaMgAl 11 O 19 -type magnetoplumbite holds great promise to be used above 1300 °C as thermal barrier coatings (TBCs), but its practical application has been restricted because of inferior thermophysical properties. Herein, we focus on optimizing the thermophysical properties of LaMgAl 11 O 19 by simultaneously substituting La3+ and Al3+ ions with Nd3+ and Sc3+ ions, respectively. Results show that the effects of co-substitution on reducing thermal conductivity are pronounced. The thermal conductivities of La 1- x Nd x MgAl 11- x Sc x O 19 (x = 0, 0.1, 0.2, 0.3) ceramics decrease progressively with dopant concentration and a lowest thermal conductivity of 2.04 W/(m·K) is achieved with x = 0.3 at 1000 °C, which is a value superior to pure LMA and even lower than YSZ. The mechanisms behind the lowered thermal conductivity are investigated. Increase of the thermal expansion coefficient is also realized (8.53 × 10−6 K−1 for pure LMA, 9.07 × 10−6 K−1 for x = 0.3, 1300 °C). Most importantly, Nd3+ and Sc3+ combination doping indeed facilitates mechanical properties of La 1- x Nd x MgAl 11- x Sc x O 19 solid solutions as well. It should be noted that Sc3+ doping at Al3+ site plays more effective role in improving thermal properties than Nd3+ does at La3+ site. This work provides a path to simultaneously integrate low thermal conductivity, good phase stability, moderate thermal expansion behavior and excellent mechanical properties on LMA for the next generation TBCs. [ABSTRACT FROM AUTHOR]

The microstructure and lattice misfit of a γ′-rich superalloy during an ultra-high temperature thermal cycle (25–1200 °C) were studied. The cubic γ' precipitate gradually dissolved as the temperature increased from 900 °C to 1200 °C. Upon subsequent cooling, numerous tiny secondary γ' phases precipitated from the supersaturated γ channel. The microstructure was composed of a bimodal distribution of coarsened primary γ' and secondary γ' after the first ultra-high temperature thermal cycle. In subsequent thermal cycles, the secondary γ' dissolved gradually (or re-precipitated), and the primary γ' remained relatively stable. The dissolution of the γ′ phase led to a smaller absolute value of the lattice misfit. Interestingly, the lattice misfit was strongly dependent on the variation of the γ′ volume fraction during the thermal cycles, which exhibited good inheritance. [ABSTRACT FROM AUTHOR]

Estrogen deficiency and inflammation are known to play important roles in bone metabolism and occurrence of osteoporosis. Monotropein as an iridoid glycoside is reported to decrease estrogen deficiency-induced bone loss and inhibit inflammatory response in LPS-induced RAW 264.7 macrophages. However, the effect of monotropein on bone loss in chronic inflammatory conditions remains unclear. It was found in the present study that monotropein significantly inhibited bone mass reduction and improved bone micro-architectures by enhancing bone formation and blocking increased secretion of inflammatory cytokines in osteoporotic mice induced by combined ovariectomy and LPS. Our in vitro experiment further demonstrated that monotropein was able to increase the proliferation and activity of alkaline phosphatase (ALP), bone matrix mineralization and the expression of bone matrix protein osteopontin (OPN) in osteoblastic MC3T3-E1 cells injured by LPS. In addition, monotropein significantly decreased the production of IL-6 and IL-1β, inhibited the nuclear translocation of p65 and NF-κB P50, and down-regulated the phosphorylation of NF-κB p65 and IKK, indicating that monotropein could attenuate inflammatory impairment to MC3T3-E1 cells by suppressing the activation of NF-κB pathway. All these results suggest that monotropein may prove to be a promising candidate for the prevention and treatment of inflammatory bone loss. [ABSTRACT FROM AUTHOR]

The high theoretical capacity of silicon (Si) makes it an attractive anode for lithium-ion batteries (LIBs). However, the poor cycle performance due to the volumetric expansion of Si during the charging-discharging process hinders its practical applications. A composite of graphene and silicon can buffer effectively the volumetric expansion of Si during the charging and discharging process of the battery. Herewith we describe a honeycomb structure constructed with Si nanoparticles (NPs), acetylene black (ACET), and reduced graphene (rGO). In this 3D structure, ACET and Si formed a Si/C composite by mechanical ball milling and it was then encapsulated in a graphene oxide (GO) suspension. After reduction with hydrazine hydrate (N 2 H 4 ·H 2 O) to create rGO, a stable composite Si/C/rGO was obtained. As an anode for LIB, the Si/C/rGO composite exhibited excellent cycle and rate performance. Firstly, the initial coulombic efficiency (ICE) of the battery is very high, exceeding 85%. Secondly, the reversible capacity was retained at 1004 mAh/g after 270 cycles at a current density of 1 A/g. The composite maintained good cycling stability even at current densities of 2 and 3 A/g. Finally, in the rate cycle test, the reversible capacity was up to 450 mAh/g at 5 A/g. [Display omitted] • Forming N-C, C-O-N chemical bonds in Si/C/rGO composite. • Initial coulombic efficiency exceeded 85%. • Specific capacity remained 1004 mAh/g at 1 A/g after 270 cycles. • Rate performance was excellent with capacity of 460 mAh/g at 5 A/g. [ABSTRACT FROM AUTHOR]

As a new kind family of lead-free Na 0.5 Bi 0.5 TiO 3 (NBT) ceramics, bismuth layer-structured ferroelectrics (BLSFs), Na 0.5 Bi 4.5 Ti 4 Mg x O 15+ x and Na 0.5 Bi 4.5 Ti 4- x Mg x O 15- x ceramics (with x = 0.04, 0.08) were artificially compounded by a conventional mixed oxide route. Under different sintering temperatures, we changed the Ti content of ceramics or Mg-doping on Ti-site in order to explore the ferroelectric and dielectric properties. XRD standard patterns of Na 0.5 Bi 4.5 Ti 4 Mg x O 15+ x and Na 0.5 Bi 4.5 Ti 4- x Mg x O 15- x (with x = 0.04, 0.08) proved that the materials were a single phase of BLSFs. By analysing the data of impedance spectra, we found that the Na 0.5 Bi 4.5 Ti 4 Mg 0.04 O 15.04 ceramics sintered at 1100 °C showed prominent dielectric properties with a dielectric constant of 1915.65 at 100 kHz and a dielectric loss of 0.0020 at 1 MHz, which were enhanced much compared with other samples. Meanwhile, the Curie temperature ( T c ) of all samples were about 660 °C. Moreover, the ferroelectric hysteresis loops of all the samples revealed that they were ferroelectric materials, which possessed a remanent polarization (2 P r ) from 5.16 to 8.78 µC/cm 2 and a coercive field from 101 to 127.78 kV/cm. The cross-section SEM showed that all samples had no c-axis orientation, whose grain distribution was more and more uniform and regular when activation energy ( E a ) increased. The E a can be calculated in the range of 1.10–1.47 eV, which indicated they were dielectric ceramics. Consequently, the ceramics have the prospect of application in high-temperature capacitors and phase shifter field because of their high dielectric constant, low dielectric loss and wide operating temperature range. [ABSTRACT FROM AUTHOR]

As a new kind family of lead-free Na 0.5 Bi 0.5 TiO 3 (NBT) ceramics, bismuth layer-structured ferroelectrics (BLSFs), Na 0.5 Bi x Ti 3.98 Mg 0.02 O y ( x = 4.48, 4.50, 4.52) were synthesized by a conventional mixed oxide route. Studies have found that the dielectric properties of Na 0.5 Bi 4.5 Ti 4 O 15 can be optimized through changing the Bi content of the ceramics or Mg-doping on Ti-site under different sintering temperatures. X-ray diffraction analysis indicated that the new material was in a single BLSFs phase. The dielectric constant of Mg-doped Na 0.5 Bi 4.5 Ti 3.98 Mg 0.02 O y was improved and dielectric loss of Na 0.5 Bi 4.5 Ti 3.98 Mg 0.02 O y changed slowly under 500 °C with the increased sintering temperature. We found that the dielectric properties of the sample sintered at 1120 °C with the highest permittivity of 1122.5 and the lowest dielectric loss of 0.01 were relatively better than those of the other samples. SEM can be better to explain the results of the dielectric spectrum at different sintering temperatures through grain size mechanics. Z* plots showed that Na 0.5 Bi 4.5 Ti 3.98 Mg 0.02 O y ceramics are a kind of dielectrics. Thus, Na 0.5 Bi x Ti 3.98 Mg 0.02 O y ( x = 4.48, 4.50, 4.52) can be used as high-temperature capacitors and phase shifter with high dielectric constant, low dielectric loss and wide operating temperature range. [ABSTRACT FROM AUTHOR]

It is important to study the stress effects and mechanisms of haloacetamide (HAcAm) disinfection byproducts to reveal their health hazards. In this context, toxicological g was applied to evaluate the effects of four HAcAms, revealing the status of gene expression on Escherichia coli in different stress response types (oxidative, protein, membrane, general, DNA). This study revealed that the main toxic action modes of these HAcAms were general and membrane stresses by high-resolution, real-time gene expression profiling combined with clustering analysis. The results of time-gene evaluation showed that the presence of chloroacetamide (CAcAm) and bromoacetamide (BAcAm) generated more reactive oxygen species, thus activating oxidative stress. Trichloroacetamide (tCAcAm) induced altered expression of glutathione marker genes and membrane stress-related genes, and iodoacetamide (IAcAm) caused severe DNA damage by damaging DNA strands and individual nucleotides mainly through damage to nucleic acids and bases. Furthermore, quantitative structure-activity relationship (QSAR) modelling results indicated that the biological activities of HAcAms were related to their quantum chemical and topological properties. [Display omitted] • Quantitative toxicological genomics method was applied. • Toxic effects and action modes of four HAcAms were investigated. • The biological activity of HAcAms related to its physicochemical structure. • More work required on understanding HAcAms risk exposure. [ABSTRACT FROM AUTHOR]

An improved Hummers method for preparing graphene oxide (GO) has been developed using boric acid (H 3 BO 3) to replace sodium nitrate (NaNO 3). This modification can shorten the reaction time to 1 h at room temperature, inhibit effectively the generation of carbonyl and carboxyl groups, eliminate the emission of toxic gases of nitrogen dioxide (NO 2) and dinitrogen tetroxide (N 2 O 4), and increase the yield by 10% in GO production. While the morphology of GO synthesized by the modified Hummers method, observed by SEM and TEM, is similar to that of the traditional Hummers method, Raman analysis found that the GO synthesized herein has fewer structural defects than the traditional Hummers method. XPS analysis indicated that boric acid had a significant inhibitory effect on the carbonyl groups. Boric acid could mitigate the formation of carbonyl groups, but did not prevent the formation of carbonyl groups. The Hummers method utilizes H 3 BO 3 instead of NaNO 3 to protect the functional groups in the basal plane of GO, reduce structural defects, and inhibit the generation of carbonyl and carboxyl functional groups. [Display omitted] [ABSTRACT FROM AUTHOR]

High-performance ternary cobalt-based metal oxides, especially ZnCo 2 O 4 , have attracted increasing attention as promising electrode materials for supercapacitors. However, there are still great challenges for the as-reported ZnCo 2 O 4 materials, such as self-aggregation during repeated discharging-charging process and low packing density. To tackle the above issues, it is envisaged as an efficient strategy to combine the advantages of both hierarchical porous micro/nanostructures and self-supporting electrode to fabricate a free-standing hierarchical micro/nanostructured ZnCo 2 O 4 electrode. Herein we propose an efficient and simple synthetic strategy for the controllable synthesis of self-supporting hierarchical porous cactus-like ZnCo 2 O 4 material directly grown on Ni-foam using a facile hydrothermal method with post-calcination treatment. Furthermore, a growth mechanism is also proposed. The as-prepared cactus-like ZnCo 2 O 4 material possesses unique structural merits, such as hierarchical porous structures, large specific surface area, robust structural stability, and strong connections between the substrate and the ZnCo 2 O 4 active material. The unique cactus-like ZnCo 2 O 4 film electrode displayed excellent electrochemical performance, including a high specific capacity of 1115.7 F g−1 at 1 A g−1 and remarkable long cycle stability with 80.8% capacity retention after 30,000 cycles. A practical asymmetric supercapacitor (ASC) device was assembled using cactus-like ZnCo 2 O 4 and active carbon, which showed an excellent energy density of 35.4 Wh kg−1 at high power density of 160.1 W kg−1 and superior cycle stability (62.5% capacity retention after 30,000 cycles at 1 A g−1). All these results show that such hierarchical porous ZnCo 2 O 4 micro/nanostructured films are a promising candidate for high-performance supercapacitors for energy storage application. [Display omitted] • 3D hierarchical porous cactus-like ZnCo 2 O 4 film is grown on Ni foam. • A growth mechanism of the 3D cactus-like ZnCo 2 O 4 film is proposed. • The cactus-like ZnCo 2 O 4 electrode shows 80.8% capacitance retention after 30,000 cycles at 5 A g−1. • The ZnCo 2 O 4 @NF//AC asymmetric supercapacitor exhibits an excellent energy density and power density. [ABSTRACT FROM AUTHOR]

CD40 and CD154 are well-characterized costimulatory molecules involved in adaptive humoral immunity in humans and other mammals. These two costimulatory molecules were found to be originated from teleost fish during vertebrate evolution. However, the functionality of fish CD40 and CD154 remains to be explored. In this study, we identified the CD40 and CD154 homologs (Lc CD40 and Lc CD154) from large yellow croaker (Larimichthys crocea), a marine species of the perciform fish family. The Lc CD40 and Lc CD154 share conserved structural features to their mammalian counterparts, and are widely expressed in immune-relevant tissues and leukocytes at different transcriptional levels. Immunofluorescence staining and FCM analysis showed that Lc CD40 and Lc CD154 proteins are distributed on MHC-II+ APCs and CD4-2+ T cells, and are significantly upregulated in response to antigen stimulation. Co-IP assay exhibited strong association between Lc CD40 and Lc CD154 proteins. Blockade of Lc CD154 with anti- Lc CD154 antibody (Ab) or recombinant soluble Lc CD40-Ig fusion protein remarkably decreased the MHC-II+ APC-initiated CD4+ T cell response upon Aeromonas hydrophila stimulation, and alloreactive T cell activation as examined by mixed lymphocyte reaction (MLR). These findings highlight the costimulatory role of Lc CD40 and Lc CD154 in T cell activities in Larimichthys crocea. Thus, the CD40 and CD154 costimulators may extensively participate in the regulation of multiple T cell-mediated immune responses in teleost fish. It is anticipated that this study would provide a cross-species understanding of the evolutionary history of CD40 and CD154 costimulatory signals from fish to mammals. • Identification of CD40/CD154 in perciform fish provides further evidence for the origin of these two costimulators in fish. • CD40/CD154 regulate APC-initiated CD4+ T cell activation in fish. • CD40/CD154 are involved in regulating allogeneic T cell reaction in fish. [ABSTRACT FROM AUTHOR]

Bioretention has been considered as an effective management practice for urban stormwater in the removal of pollutants including polycyclic aromatic hydrocarbons (PAHs). However, the accumulation of high-molecular-weight (HMW) PAHs in bioretention systems and their potential impact on the pollutants removal performance and microbial ecology are still not fully understood. In this study, comparisons of treatment effectiveness, enzyme activity and microbial community in bioretention systems with different types of media amendments were carried out at different spiking levels of pyrene (PYR). The results showed that the removal efficiencies of chemical oxygen demand (COD) and total nitrogen in the bioretention systems were negatively impacted by the PYR levels. The relative activities of soil dehydrogenase and urease were increasingly inhibited by the elevated PYR level, indicating the declining microbial activity regarding organic matter decomposition. The spiking of PYR negatively affected microbial diversity, and distinct time- and influent-dependent changes in microbial communities were observed. The relative abundance of PAH-degrading microorganisms increased in PYR-spiked systems, while the abundance of nitrifiers decreased. The addition of media amendments was beneficial for the enrichment of microorganisms that are more resistant to PYR-related stress, therefore elevating the COD concentration removal rate by ∼50%. This study gives new insight into the multifaceted impacts of HMW PAH accumulation on microbial fingerprinting and enzyme activities, which may provide guidance on better stormwater management practices via bioretention in terms of improved system longevity and performance. [Display omitted] • Impacts of HMW PAH accumulation on bioretention systems are investigated. • High level of pyrene had negative effects on organic matter and nitrogen removal. • Microbial activities of dehydrogenase and urease were inhibited by pyrene addition. • Spiked systems had lower microbial diversity and higher abundance of PAH degraders. • Addition of media amendments lowered pyrene-induced stress and improved performance. [ABSTRACT FROM AUTHOR]

Carbon nanotube spaced graphene aerogels have been prepared by a hydrothermal method and used for supercapacitor applications. The specific surface area and specific capacitance can be controlled by tuning the amount of added carbon nanotubes. The as-prepared composite aerogels retain the advantage of aerogel structure in providing macropores to ensure electrodes fast wetted by the electrolyte ions and also possess additional mesopores created by the carbon nanotube spacers for more ion adsorption. Benefited from that, the composite aerogels exhibit significantly enhanced supercapacitor properties in both aqueous and ionic liquid electrolyte. Compared with graphene aerogels, the composite aerogels show a 37% larger specific capacitance of 245.5 F g −1 at a current density of 2.5 A g −1 and high rate capability of 197.0 F g −1 at a high current density of 80 A g −1 in aqueous electrolyte. Moreover, the composite aerogels deliver a 33% larger specific capacitance of 183.3 F g −1 at 0.5 A g −1 and a high energy density of 80 Wh kg −1 when using an ionic liquid (EMIMBF 4 ) as the electrolyte. [ABSTRACT FROM AUTHOR]

The BTLA and HVEM are two well-characterized immune checkpoint inhibitors in humans and other mammalian species. However, the occurrence and functionality of these two molecules in non-mammalian species remain poorly understood. In the present study, we identified the BTLA and HVEM homologs from large yellow croaker (Larimichthys crocea), an economically important marine species of the perciform fish family. The Larimichthys crocea BTLA and HVEM (Lc BTLA and Lc HVEM) share conserved structural features to their mammalian counterparts, and they were expressed in various tissues and cells examined at different transcriptional levels, with particular abundance in immune-relevant tissues and splenic leukocytes. Immunofluorescence staining and flow cytometry analysis showed that Lc HVEM and Lc BTLA proteins were distributed on MHC-II+ APCs and CD4-2+ T cells, and a strong interaction between Lc BTLA and Lc HVEM was detected in splenic leukocytes in the mixed lymphocyte reaction (MLR). By blockade assays using anti- Lc BTLA and anti- Lc HVEM Abs as well as recombinant soluble Lc BTLA and Lc HVEM proteins in different combinations, it was found that Lc BTLA- Lc HVEM interactions play an important inhibitory role in the activation of alloreactive T cells using MLR as a model, and APC-initiated antigen-specific CD4-2+ T cells in response to A. hydrophila (A. h) stimulation. These observations highlight the extensive functional roles of Lc BTLA and Lc HVEM immune-checkpoint inhibitors in allogeneic T cell reactions, and CD4-2+ T cell-mediated adaptive immune responses in Larimichthys crocea. Thus, the BTLA-HVEM checkpoint may represent an ancient coinhibitory pathway, which was originated in fish and was conserved from fish to mammals throughout the vertebrate evolution. • Identification of BTLA-HVEM checkpoint inhibitors in perciform fish Larimichthys crocea. • Regulatory role of BTLA-HVEM checkpoint in the activation of alloreactive T and antigen-specific CD4+ T cells. • BTLA-HVEM checkpoint is an ancient coinhibitory mechanism originated as early as in teleost fish. [ABSTRACT FROM AUTHOR]

Abstract: Graphene and single-walled carbon nanotube (CNT) composites are explored as the electrodes for supercapacitors by coating polyaniline (PANI) nano-cones onto the graphene/CNT composite to obtain graphene/CNT–PANI composite electrode. The graphene/CNT–PANI electrode is assembled with a graphene/CNT electrode into an asymmetric pseudocapacitor and a highest energy density of 188 Wh kg−1 and maximum power density of 200 kW kg−1 are achieved. The structure and morphology of the graphene/CNT composite and the PANI nano-cone coatings are characterized by both scanning electron microscopy and transmission electron microscopy. The excellent performance of the assembled supercapacitors is also discussed and it is attributed to (i) effective utilization of the large surface area of the three-dimensional network structure of graphene-based composite, (ii) the presence of CNT in the composite preventing graphene from re-stacking, and (ii) uniform and vertically aligned PANI coating on graphene offering increased electrical conductivity. [Copyright &y& Elsevier]

Abstract: Sm and SmZn substituted nanocrystalline barium hexaferrites (Ba1−x Sm x Fe12O19 and Ba1−x Sm x Fe12−x Zn x O19, x =0–0.6) were prepared by the sol–gel autocombustion process. X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) were used to characterize the phase composition, crystal structure and magnetic properties of the as-prepared barium hexaferrites. All results indicated that the substitution content (x) critically influenced on the phase composition and magnetic properties. When the substitution content x >0.2, impurity phases such as α-Fe2O3, SmFeO3 and ZnFe2O4 were detected, which diluted and weakened saturation magnetization (M s). For the Sm-doped samples, owing to the hyperfine field, canting spin, magnetic dilution and impurity phases, M s increased with x firstly, and then decreased when x >0.03. On the other hand, the coercivity (Hc) continuously increased with x. Nevertheless, for the SmZn-doped samples, M s reached maximum when x =0.06 and Hc almost unchanged with x. Compared the magnetic properties of Sm- and SmZn-doped samples, it was proved that Zn2+ substituted Fe3+ at 4f 2 sites and Sm3+ substituted Ba2+, which changed Fe3+ to Fe2+ at 2a sites in order to satisfy the electroneutrality principle. [Copyright &y& Elsevier]

Graphene has been widely used as an electrode material for supercapacitors. However, parallelly-stacked graphene layers often result in inefficient ion diffusion and electron transfers that usually reduce the rate capability of a supercapacitor. In this study, reduced graphene oxide (rGO) and poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) composite films were prepared by a solvent evaporation method using PEDOT:PSS as the binder to fix aligned graphene for its good conductivity and strong π-π stacking interactions with the graphene sheets. Analyses using scanning electron microscopy (SEM), nitrogen adsorption-desorption, and small-angle X-ray scattering show that the graphene sheets were well aligned when a magnetic field was applied, though they were oriented randomly without the magnetic field. As a capacitor electrode material, the aligned rGO shows a specific capacitance of 169 F g−1 with a capacitance retention of about 70% at a current density of 50 A g−1 and its cyclic voltammetry (CV) loops maintained a rectangular shape at a voltage scan rate of 2 V s−1. The aligned rGO electrode can help break through the limitations of traditional supercapacitors and increase significantly their charge/discharge rate and power density. Image 1 • Electrode is developed with graphene aligned vertically in 12T magnetic field. • The electrode has a capacitance retention of 70% at current density of 50 A g−1. • The stability of the vertically aligned structure is outstanding. [ABSTRACT FROM AUTHOR]

Abstract: Single-crystalline K2Nb8O21 nanoribbons with width of 100–500nm and thickness of ca. 30nm, and length up to tens of micron, have been successfully synthesized by simply calcining Nb2O5 powders in molten KCl, and characterized with XRD, SEM, SEM, HRTEM and selected-area electron diffraction technique. The growth direction of the obtained K2Nb8O21 nanoribbons was determined to be the 〈100〉 crystallography direction. [Copyright &y& Elsevier]