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Rotational piezoelectric energy harvesters which can directly convert mechanical energy into electrical energy are considered as one of the most attractive harvesters for self-powered rotational wireless monitoring systems. In this paper, a trapezoid piezoelectric cantilever beam is proposed to improve the output of rotational piezoelectric energy harvester. Finite element simulation results indicate that the trapezoid beam harvester can bear higher stress than the rectangle beam harvester near the clamping end and show excellent electrical output properties. The experimental results are consistent with the simulation analysis results, and verify that the rotational piezoelectric energy harvesters are endowed with the characters of up-conversion frequency and ring-down pattern. Experimentally, a prototype trapezoid beam harvester has been fabricated to harvest wind energy, which can generate an average output power density of 0.64 mW/cm2 at the matching impedance of 50 kΩ. Our work has demonstrated that the proposed trapezoid beam harvester is a good potential generator for harvesting flow energies and monitoring conditions of rotating machinery. [ABSTRACT FROM AUTHOR]

Perovskite-type Ca 1−2 x Dy x Yb x MnO 3 (0≤ x ≤0.10) ceramics were synthesized by solid state reaction. Microstructures were characterized and thermoelectric properties were evaluated between 300 K and 1100 K. The samples obtained in this work have high relative densities with compact grains. The electrical resistivity shows a typical metallic conductivity behavior, and decreases with substitution. The Seebeck coefficients are negative, indicating n-type conduction, and the largest value is obtained −181 μV/K at x =0.02. The highest power factor 415 μW/(K 2 m) and the highest figure of merit 0.27 are both obtained for x =0.02 sample, and the ZT is about five times as much as un-doped CaMnO 3 sample. [ABSTRACT FROM AUTHOR]

Abstract: The hot flow behaviors of 20CrMnTiH steel are studied using isothermal compression tests corresponding to the temperature range from 973 to 1123K and the strain rates range from 0.01 to 10s−1. The flow behaviors of 20CrMnTiH steel are represented, which are based on the analysis of true stress–true strain curves. The results show that there exist typical dynamic recovery (DRV) and dynamic recrystallization (DRX) during hot deformation. The effect of hot deformation on microstructure is investigated. There exists a dual phase feature within the deformation temperature. A modified Zerilli–Armstrong (ZA) model, based upon the original ZA model and Johnson–Cook model, is proposed to describe the flow stress under different deformation conditions. Compared with experimental data, the modified ZA model has a good accuracy in describing the constitutive relation of the material. [Copyright &y& Elsevier]

The nonlinear electrical behavior and dielectric properties of TiO2-based ceramics with various WO3 contents have been investigated. It was found that the 0.25% WO3+99.75% TiO2 has an optimal nonlinear coefficient α of 9.6, a breakdown electrical field of 44.5 V mm−1, and an ultrahigh relative dielectric constant of 7.41×104 (measured at 1 kHz). The theory of defects in the crystal lattice was introduced to explain the nonlinear electrical behavior of the TiO2·WO3 system. A grain boundary barrier model that is analogous to the grain boundary defect model for ZnO varistors are introduced in the article. From this point, the nonlinear electrical behavior of the TiO2 system is explained. [Copyright &y& Elsevier]

• A novel water-forming flavin oxidoreductase was first expressed and characterized. • A rate-limiting Thr29 was identified and confirmed to be employed to improve its activity. • The distance between FMN and NADH was shortened by introducing a small side chain containing residue into position 29. Enzyme-catalyzed cofactor regeneration is a significant approach to avoid large quantities consumption of oxidized cofactor, which is vital in a variety of bioconversion reactions. NADH: FMN oxidoreductase is an ideal regenerating enzyme because innocuous molecular oxygen is required as an oxidant. But the by-product H 2 O 2 limits its further applications at the industrial scale. Here, novel NADH: FMN oxidoreductase (LrFOR) from Lactobacillus rhamnosus comprised of 1146 bp with a predicted molecular weight of 42 kDa was cloned and overexpressed in Escherichia coli BL21 (DE3). Enzyme assay shows that the purified recombinant LrFOR has both the NADPH and NADH oxidation activity. Biochemical characterizations suggested that LrFOR exhibits the specific activity of 39.8 U·mg−1 with the optimal pH and temperature of 5.6 and 35 °C and produces H 2 O instead of potentially harmful peroxide. To further study its catalytic function, a critical Thr29 residue and its six mutants were investigated. Mutants T29G, T29A, and T29D show notable enhancement in activities compared with the wild type. Molecular docking of NADH into wild type and its mutants reveal that a small size or electronegative of residue in position29 could shorten the distance of NADH and FMN, promoting the electrons transfer and resulting in the increased activity. This work reveals the pivotal role of position 29 in the catalytic function of LrFOR and provides effective catalysts in NAD+ regeneration. [ABSTRACT FROM AUTHOR]

Abstract Composition in (Zn 0.98-y In y) (y = 0.05, 0.02, 0.01, 0.005) were fabricated via conventional solid-state sintering route under an argon atmosphere at 1400 °C for 10 h (h) their phases, microstructures and thermoelectrical properties were investigated. Single phase ceramics were formed for the composition with y ≤ 0.05. The highest power factor (PF) of 481.8 µW K−2 m−1 ± 0.2, Seebeck coefficient −98.08 µV K−1 ± 0.2 and electrical resistivity (ρ) of 1.997 mΩ cm ± 0.2 was obtained for x = 0.02, y = 0.005 i.e., (Zn 0.975 Al 0.02 In 0.005)O. It is studied that PF is a function of lattice parameter c/a ratio. The resistivities of all the compositions were tuned. These tuned resistivities will be helpful for future thermoelectric devices. [ABSTRACT FROM AUTHOR]

Abstract: The isothermal crystallization kinetics and morphology development of isotactic polypropylene (iPP) blended with small loading of nanostructure of polyhedral oligomeric silsesquioxane (POSS) were studied with differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray diffraction (WAXD). The crystallization behaviors of iPP/POSS composites presented an unusual crystallization behavior during isothermal and nonisothermal crystallization conditions. The exothermic morphologies of isothermal and nonisothermal crystallization of iPP/POSS composites changed remarkably with increasing POSS. Moreover, the developments of spherulitic morphology for iPP/POSS composites showed that the major dispersed POSS molecules became nanocrystals first and then aggregated together forming thread- or network-like morphologies, respectively, depending on POSS content, which was observed. It implies that these major POSS nanocrystals'' morphologies appeared as an effective nucleating agent and promoted the nucleation rate of iPP, whereas the minor dispersed POSS molecules that had slight miscibility between iPP retarded the nucleation and growth rates of iPP in the remaining bulk region. Therefore, the isothermal crystallization showed a single exothermic peak at pure iPP and POSS-1.0, whereas at POSS-2.0 and POSS-3.0, displayed the multi-exothermic peaks during isothermal crystallization. These faces indicated that POSS molecules were both influence on the transport of iPP chain in the melted state and on the free-energy of formation the critical nuclei of iPP assisted by the POSS structures were observed. Therefore, we postulated that the crystallization mechanisms of multi-exothermic peaks in isothermal crystallization may proceed to combine the “nucleating agent inducing nucleation of iPP event assisted by the POSS domains” that the nucleation of iPP does occur preferentially on the surfaces of the POSS “threads” or “networks” structures, and “nucleation and growth of iPP in the remaining bulk melted iPP region retarded by dispersed POSS molecules”. Therefore, effects of POSS content on the isothermal and nonisothermal crystallization behaviors of iPP/POSS composites due to the POSS molecules partially miscible with iPP, at very small loading of POSS molecules, promoted or retarded the rates of nucleation and growth of iPP depending on the POSS content and crystallization temperature were discussed. [Copyright &y& Elsevier]

Abstract: The effect on the microstructure and electrical properties of (Co, Ta)-doped SnO2 varistors upon the addition of SrCO3 was investigated. The threshold electric field of the SnO2-based varistors increased significantly from 318 to 3624V/mm, the relative dielectric constants of the SnO2-based varistors decreased greatly from 1509 to 69 as SrCO3 concentration was increased up to 2.5mol%. The significant decrease of the SnO2 grain size, from 8.19 to 1.03μm with increasing SrCO3 concentration over the range of 0–2.5mol%, is the origin for increase in the threshold voltage and decrease of the dielectric constants. The grain size reduction is attributed to the segregation of SrCO3 at grain boundaries hindering the SnO2 grains from conglomerating into large particles. Varistors were found to have superhigh threshold voltage and comparatively large nonlinear coefficient α. For 1.5mol% SrCO3-doped sample, threshold electrical field E and nonlinear coefficient α were measured to be 1738V/mm and 23.7, for 2.0mol% SrCO3-doped sample, E and α were 2204V/mm and 24, and for 2.5mol% SrCO3-doped sample, E and α were 3624V/mm and 22. Superhigh threshold voltage and large nonlinear coefficient qualify the Sr-doped SnO2 varistor as an excellent candidate in use for high voltage protection system. The reasons why the grain resistivity of the SnO2-based varistors increased with increasing SrCO3 concentration and the boundary resistivity of the SnO2-based varistors gradually decreased with increasing SrCO3 concentration were explained. [Copyright &y& Elsevier]

Abstract: The effects of Dy2O3 on the microstructure and electrical properties of the SnO2 based varistor system were investigated. It was found that Dy2O3 significantly affects the grain size and electrical properties of the SnO2-based varistors. The sample with 1.00mol% Dy2O3 has the best nonlinear electrical property and the highest nonlinear coefficient (α =26.3) among all samples. By SEM, TEM and EDS images, it was found dysprosium segregates at the grain boundary, which is responsible for “p-type characteristics” of the grain boundaries. The reason that grain size decreases with increasing Dy2O3 concentration is given. The reason why the varistor sample has the excellent nonlinearity is explained. [Copyright &y& Elsevier]

Abstract: The effect on microstructual and electrical properties of (Co, Nb)-doped SnO2 varistors upon the addition of Er2O3 was investigated by scanning electron microscopy and I–V and ε–f relations’ measurements. The threshold electric field of the SnO2-based varistors increased significantly from 305Vmm-1 to 1083Vmm-1, from 384Vmm-1 to 1300Vmm-1, and from 532Vmm-1 to 2270Vmm-1 for samples sintered at 1350°C, 1300°C and 1250°C, respectively, for 1h separately. The relative dielectric constants of the SnO2-based varistors decreased greatly from 2003 to 451 as Er2O3 concentration was increased up to 2.0mol% sintered at 1350°C for 1h, from 1258 to 339 sintered at 1300°C for 1h and from 988 to 185 sintered at 1250°C for 1h. The significant decrease of the SnO2 grain size was found with the Er2O3 dopant for the samples sintered at various temperatures, which is the origin for the increase in the threshold voltage and decrease in the dielectric constants. The grain-size reduction is attributed to the segregation of Er2O3 at grain boundaries, which hinders the SnO2 grains from conglomerating into large particles. Varistors were found to have high density and fairly stable nonlinear coefficient α. For all Er2O3-doped samples, relative density was measured to be more than 98.00% except x=2.0mol% sintered at 1250°C during 1h and nonlinear coefficient α was measured to be around 16. High density and stable nonlinear coefficient α qualify the Er-doped SnO2 varistor as a comparative candidate for high-voltage protection system. [Copyright &y& Elsevier]

Abstract: The CuO and Ta2O5-doped SnO2 system was obtained by conventional ceramics processing. The ceramic phases of samples was analyzed by X-ray diffraction (XRD) and the microstructure by means of scanning electron microscopy (SEM). The electrical field of a single phase of CuO and Ta2O5-doped SnO2 system was studied as a function of current density behavior and compared with the CoO and Ta2O5-doped SnO2 system. A high nonlinear coefficient α=37.9 was obtained. To illustrate the grain–boundary barrier formation of CuO and Ta2O5-doped SnO2-based varistors, a modified defect barrier model is introduced. [Copyright &y& Elsevier]

Abstract: This study assessed the antibody persistence, and the immunogenicity and safety of a booster dose of a DTaP–IPV//PRP∼T (Pentaxim®, Sanofi Pasteur''s AcXim family) combined vaccine and of standalone vaccines one year after primary vaccination in the People''s Republic of China. Participants (N =719) previously primed with DTaP–IPV//PRP∼T at 2, 3, 4months (Group A, N =255), 3, 4, 5months (Group B, N =233), or DTaP (Wuhan Institute of Biological Products), PRP-T (Act-Hib®) and IPV (Imovax® Polio) at 3, 4, 5months (Group C, N =231) received boosters of the same vaccines at 18–20months of age. Seroprotection (SP) and seroconversion (SC) were determined before and 1month after the booster. Safety was monitored from parental reports. In all groups 87.6–100% of participants had pre-booster protective anti-PRP, -diphtheria, -tetanus and -poliovirus antibody titers; post-booster, all SP rates were 100% and SC was ≥80.4% for anti-pertussis titers ≥ 4-fold increase. Reactogenicity was low for each group. These data support the use of the DTaP–IPV//PRP∼T vaccine in the People''s Republic of China compared to separate DTaP, IPV, and PRP∼T administration in terms of both safety and immunogenicity. [Copyright &y& Elsevier]

Abstract: The aim was to demonstrate the immunogenicity and safety of a DTaP-IPV//PRP-T combined vaccine (Pentaxim®) compared to individual vaccines in infants in the People''s Republic of China. Infants (N =792) were randomly assigned to receive DTaP-IPV//PRP-T at 2, 3 and 4 months of age (Group A) or 3, 4 and 5 months of age (Group B), or DTaP (Wuhan Institute of Biological Products), PRP-T (Act-Hib®) and IPV (Imovax® Polio) at 3, 4 and 5 months of age (Group C). Antibody titers were measured pre- and 1 month after the third vaccination; non-inferiority analyses were performed for seroprotection/seroconversion (SP/SC) rates. Safety was assessed 1 month after the primary series. SP/SC rates for the DTaP-IPV//PRP-T vaccine were high and non-inferior to the controls. Reactogenicity was low for each group and no hypotonic hyporesponsive episode or seizure was reported. In conclusion, the DTaP-IPV//PRP-T vaccine was highly immunogenic, non-inferior to the commercially available control vaccines and had a good safety profile for both primary administration schedules. [Copyright &y& Elsevier]

Abstract: A novel approach was developed to calculate temperature-dependent Seebeck coefficient of heavily doped systems. The electronic density of states (DOS) and Fermi energy were determined and then, using these two parameters, the Seebeck coefficient was calculated by using Boltzmann transport theory. This approach is applied to heavily La-doped SrTiO3. The calculated Seebeck coefficient agrees well with the experimental data. By analyzing the results, it was shown that Seebeck coefficient is greatly affected by the asymmetry of DOS with respect to Fermi energy. [Copyright &y& Elsevier]

Abstract: The Aurivillius type potassium lanthanum bismuth titanate (K0.5La0.5Bi4Ti4O15, KLBT) polycrystalline ceramics with 0.0–1.0wt.% CeO2 were synthesized using conventional solid-state processing. X-ray diffraction analysis revealed that the cerium-modified KLBT ceramics have a pure four-layer Aurivillius type structure. The effects of cerium oxide on the piezoelectric, ferroelectric and dielectric properties on the KLBT ceramics were investigated. By the cerium modification, the piezoelectric activities of KLBT ceramics were significantly improved and the dielectric loss decreased. The piezoelectric coefficient d 33 for the 0.50wt.% CeO2-modified KLBT was found to be 28pCN−1, the highest value among the modified KLBT-based piezoceramics. The reason for piezoelectric activities enhancement with Ce modification was given. The dielectric spectroscopy presented that the Curie temperature for all the KLBT ceramics is higher than 400°C. [Copyright &y& Elsevier]

Abstract: The morphology and thermal properties of isothermal crystallized binary blends of poly(propylene-co-ethylene) copolymer (PP-co-PE) and isotactic polypropylene (iPP) with low molecular weight polyethylene (PE) were studied with differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). In PP-co-PE/PE binary blends, however, the connected PE acted as a phase separating agent to promote phase separation for PP-co-PE/PE binary blends during crystallization. Therefore, the thermal properties of PP-co-PE/PE presented double melting peaks of PE and a single melting temperature of PP during melting trace; on the other hand, at cooling trace, the connected PE promoted crystallization rate because of enhanced segmental mobility of PP-co-PE during crystallization. At isothermal crystallization temperature between the melting points of iPP and PE, the binary blend was a crystalline/amorphous system resulting in persistent remarkable molten PE separated domains in the broken iPP spherulite. And then, when temperature was quenched to room temperature, the melted PE separated domains were crystallized that presented a crystalline/crystalline system and formed the intra-spherulite segregation morphology: these PE separated domains/droplet crystals contained mixed diluent PE with connected PE components. On the other hand, in the iPP/PE binary blends, the thermal properties showed only single melting peaks for both PE and iPP. Moreover, the glass transition temperature of iPP shifted to lower temperature with increasing PE content, implying that the diluent PE molecules were miscible with iPP to form two interfibrillar segregation morphologies: iPP-rich and PE-rich spherulites. In this work, therefore, we considered that the connected PE in PP-co-PE functioned as an effective phase separating agent for PP and diluent PE may be due to the miscibility between connected PE and diluent PE larger than that between PP and dispersed PE. [Copyright &y& Elsevier]

Abstract: The effects of Sc2O3 doping on the electrical properties of (Co, Ta, Cr)-doped SnO2 varistors were investigated and the maximal nonlinear coefficient () of the sample doped with 0.03mol% Sc2O3 was obtained. It was found that the breakdown electrical field of samples increased significantly with increasing Sc2O3 concentration and the sample doped with 0.08mol% Sc2O3 has the highest breakdown electrical field of 3336V/mm. The measurement of grain size and sample impedances reveal that the increase of grain boundary resistance is the substantial reason for the increase of breakdown electrical field. The increase of grain boundary resistance may be caused by the increase of depletion layer thickness and it can be illustrated by the decrease of relative dielectric constant with increasing Sc2O3 concentration. [Copyright &y& Elsevier]

Abstract: The effect of La2O3 additive on a SnO2-based varistor material sintered at 1350°C for 80min was investigated. It was found that La2O3 significantly decreases the grain size and improves the non-linear electrical properties of SnO2-based varistors. The sample with 1.00mol% La2O3 has the best non-linear electrical property and the highest non-linear coefficient (α=23.0) among all the samples. The reason that the grain size decreases with increasing La2O3 concentration is explained. The permittivity decrease with increasing La2O3 concentration is caused by the ratio of grain size to barrier width. A modified defect barrier model was introduced in which the negatively charged acceptors substituting for Sn ions should be located at the grain boundaries. [Copyright &y& Elsevier]

Abstract: The varistor properties of Sc2O3-doped SnO2·Co2O3·Nb2O5 ceramics were investigated. It was found that the non-linear coefficient presents a peak of 17.1 at the concentration of 0.06mol% Sc2O3, the average grain size decreases from 10 to 5μm, the breakdown electrical field increases from 199 to 1790V/mm and relative electrical permittivity decreases from 2600 to 60 as Sc2O3 concentration was increased up to 0.09mol%. The increase of the breakdown electrical field with increasing Sc2O3 concentration is mainly attributed to the decrease of the average grain size. The reason why the permittivity decreases with increasing Sc2O3 concentration was originated from the ratio of the grain size to the barrier width. To illustrate the grain-boundary barrier formation of (Sc, Co, Nb)-doped SnO2 varistors, a modified defect barrier model was introduced, in which the negatively charged acceptors substituting for Sn ions should be located at SnO2 lattice sites in the depletion layers, instead at the grain interfaces. [Copyright &y& Elsevier]

Abstract: The effects of CuO on the SnO2·Co2O3·Ta2O5 varistor system sintered at 1250°C for 80min were investigated. It was found that CuO significantly affects the grain size and electrical properties of the SnO2-based varistors. The grain size rises from 4.7 to 11.4μm, the breakdown electrical field decreases from 485 to 265Vmm−1 and relative dielectric constant (at 1kHz) increases from 970 to 2451 with an increase in CuO concentration from 0.00 to 1.00mol%. The sample with 0.25mol% CuO has the best nonlinear electrical property and the highest nonlinear coefficient (α =15.7) among all samples. The reason why grain size increases with increasing CuO concentration is explained. Also, the interpretation of the increase in nonlinearity is given. [Copyright &y& Elsevier]

The effects of Pr2O3 on the SnO2·Co2O3·Ta2O5 varistor system sintered at 1300°C for 80min were investigated. It is found that Pr2O3 affects the grain size, electrical properties and the dielectric properties of the SnO2-based varistors. The average grain size decreases from 9.4 to 5.6μm, the breakdown electrical field increases from 2460 to 11,346V/cm, relative dielectric constant (at 1kHz) falls from 1988 to 290 and the resistivity (at 1kHz) rises from 39.3 to 178.3kΩcm with an increase in Pr2O3 concentration from 0.00 to 1.00mol%. The sample with 0.10mol% Pr2O3 has the best nonlinear electrical property and the highest nonlinear coefficient (α=23.9) among all samples. The reason that the grain size decreases with increasing Pr2O3 concentration is explained. A modified defect barrier model is introduced to illustrate the grain-boundary barrier formation of Pr2O3-doped SnO2-based varistors. [Copyright &y& Elsevier]

The electrical nonlinearity of (Ni, Ta) doped SnO2 varistor system was investigated. The nonlinear coefficient α and the barrier height of this varistor system were calculated. It is found that the variations of electrical nonlinear coefficients with acceptor concentrations are in accordance with that of the barrier heights. 0.75 mol% Ni2O3 doped sample sintered at 1370 °C exhibits a high nonlinear coefficient α of 21 and a high breakdown electric field (697 V mm−1 at 1 mA cm−2), but presents a relatively low densification. Among the samples sintered at 1420 °C, the sample doped with 0.75 mol% Ni2O3 and 0.05 mol% Ta2O5 possesses the highest breakdown electric field (469 V mm−1 at 1 mA cm−2) and the highest electrical nonlinear coefficient α of 16.3, which is consistent to its highest defect barrier φB of 0.693 eV. An atom mode for the acceptors and donors to penetrate into SnO2 lattice was put forward. To illustrate the grain-boundary barrier formation of (Ni, Ta) doped SnO2 varistors, a modified defect barrier model was introduced, in which the negatively charged acceptors substituting for Sn ions should not be located at the grain interfaces instead at SnO2 lattice sites of depletion layers. [Copyright &y& Elsevier]

A best nonlinearity properties is obtained in the varistors of Sn–Ni–Nb, via the investigation of the varistors with compositions of (99.2−x)% SnO2+0.75% Ni2O3+0.05% Nb2O5+x% CuO. The sample doped with 1.0 mol% CuO exhibits the highest electrical nonlinear coefficient (α=25) and the highest relative density (96.1%). SEM micrographs show that grain size increases with increasing CuO content. The phenomenon can be explained by interface defect model, the substitution of Cu2+ for Sn4+ facilitates the formation of the defect barriers and facilitates the grain growing. Breakdown voltage increases with increasing CuO when doping less than 1.0 mol% CuO, and reaches a maximum (946 V mm−1) at 1.0 mol% CuO dopant then decreases with increasing CuO. It can also be explained by the effect of Cu2+ substituting for Sn4+. [Copyright &y& Elsevier]