Search

Ruminiclostridium papyrosolvens is an anaerobic, mesophilic, and cellulolytic clostridia, promising consolidated bioprocessing (CBP) candidate for producing renewable green chemicals from cellulose, but its metabolic engineering is limited by lack of genetic tools. Here, we firstly employed the endogenous xylan-inducible promoter to control ClosTron system for gene disruption of R. papyrosolvens. The modified ClosTron can be easily transformed into R. papyrosolvens and specifically disrupt targeting genes. Furthermore, a counter selectable system based on uracil phosphoribosyl-transferase (Upp) was successfully established and introduced into the ClosTron system, which resulted in plasmid curing rapidly. Thus, the combination of xylan-inducible ClosTron and upp-based counter selectable system makes the gene disruption more efficient and convenient for successive gene disruption in R. papyrosolvens. Key points: • Limiting expression of LtrA enhanced the transformation of ClosTron plasmids in R. papyrosolvens. • DNA targeting specificity can be improved by precise management of the expression of LtrA. • Curing of ClosTron plasmids was achieved by introducing the upp-based counter selectable system. [ABSTRACT FROM AUTHOR]

This paper provides a theoretical explanation as to why breakthrough innovations seem to be possible only within capitalist economies (Kornai in Dynamism, rivalry, and the surplus economy: Two essays on the nature of capitalism, Oxford University Press, Oxford, 2013). Specifically, our theory explains why disruptive innovations are discovered and financed by large numbers of independently owned small firms in capitalist economies rather than in socialist economies where state ownership is the only option. The key is that the ownership structure of the firm affects the ex-post selection of worthwhile discoveries, which determines the fate of disruptive innovation. Our paper also contributes to empirical work on disruptive innovation, which is missing in the literature. We use new molecular entities (NMEs) in the pharmaceutical industry as a proxy for disruptive innovation. Although pharmaceutical companies are often very large, their R&D projects greatly depend on forming alliances with much smaller independent firms. We find that the number of NMEs discovered by pharmaceutical companies is positively and significantly associated with the number of R&D alliances in which they participate. Our theory is supported by the empirical findings. [ABSTRACT FROM AUTHOR]

Avian infectious bronchitis (IB) is a highly contagious viral respiratory disease, caused by infectious bronchitis virus (IBV), that poses an important economic threat to the poultry industry. In recent years, genotypes GI-7, GI-13, and GI-19 have been the most prevalent IBV strains in China. However, in this study, we found that most IBV strains from southern China in 2016–2017 belonged to genotype GVI-1. This genotype, for which there is no vaccine, has been reported sporadically in the region. The GDTS13 strain, which caused severe IB outbreaks on the farms where it was isolated, was evaluated as a candidate vaccine strain. GDTS13 was serially passaged in specific-pathogen-free embryonated chicken eggs for 100 generations to produce GDTS13-F100. Safety testing indicated that GDTS13-F100 had no pathogenic effect on chickens. Additionally, GDTS13-F100 showed an excellent protective effect against GDTS13, with no clinical signs or virus shedding observed in immunized chickens challenged with the parent strain. These findings indicate that GVI-1 has become the most prevalent IBV genotype in southern China and that GDTS13-F100 may serve as an attenuated vaccine to protect against infection with this genotype. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions has been considered as a promising approach for green ammonia synthesis; however, non-precious metal-based catalysts with excellent NRR electrocatalytic performance have been scarce. Herein, self-supported bimetallic electrocatalysts of Ni12P5/FeP4 nanoplates grown on carbon cloth were synthesized by a combined process of hydrothermal technology and low-temperature phosphidation. The catalyst exhibits excellent electrocatalytic N2 fixation performance with a high NH3 yield rate of 3.08 × 10−10 mol s−1 cm−2 (16.40 μg h−1 mgcat−1), Faradaic efficiency (39.9%) as well good durability at − 0.1 V in 0.1 M Na2SO4 at ambient conditions, which are attributed to the distinctive nanostructure and rational composition. Our study paves the way for expanding the scope of NRR research and designing more efficient electrochemical ammonia synthesis in the future. [ABSTRACT FROM AUTHOR]

Newcastle disease (ND), caused by virulent Newcastle disease virus (NDV) strains, has been one of the most problematic diseases affecting the poultry industry worldwide. Conventional vaccines provide effective protection for birds to survive ND outbreaks, but they may not completely suppress NDV shedding. NDV strains circulate on farms for a long time after the initial infection and cause potential risks. A new vaccine with fast clearance ability and low viral shedding is needed. In this study, we used interleukin-12 (IL-12) as an adjuvant and electroporation (EP) as an advanced delivery system to improve a DNA vaccine candidate. The fusion (F) protein gene from an NDV strain of the prevalent genotype VII.1.1 was cloned to prepare the vaccine. Chickens immunized with the F gene DNA vaccine co-delivered with an IL-12-expressing plasmid DNA showed higher neutralizing antibody levels and stronger concanavalin-A-induced lymphocyte proliferation than those treated with the F gene DNA vaccine alone. The co-delivered vaccine provided 100% protection, and less viral shedding and a shorter release time were observed in challenged chickens than when the F gene DNA vaccine was administered alone. The use of F gene DNA combined with IL-12 delivered by electroporation is a promising approach for vaccination against ND. [ABSTRACT FROM AUTHOR]

Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) is a kind of potential biological insecticide. Ac-PK2 protein encoded by orf123 in AcMNPV genome can inhibit eIF2α family kinases to increase viral adaptation in vivo. In our previous study, it was found that recombinant AcMNPV-PK2-EGFP showed high virulence and anti-insect activity against Sf9 cells and Spodoptera exigua larvae. In this study, we investigated the function of Ac-PK2 protein in the insecticidal activity of AcMNPV and the anti-insect mechanism. AcMNPV-PK2-EGFP up-regulated the expression of Ac-pk2 gene in midgut and nerve cord in infected Spodoptera exigua larvae, compared with these in wild-type treatment group. Transcriptional level of BmK IT and detoxication related genes in epidermis, midgut and nerve cord was detected by quantitative PCR. Phenoloxidase activity assay showed that the insect's humoral immunity was affected by AcMNPV-PK2-EGFP in a time-effect relationship. Western blot analysis of P53 protein indicated the apoptotic level in the midgut tissue was higher in AcMNPV-BmK IT and AcMNPV-PK2-EGFP co-infeced Spodoptera exigua larvae than that in other treatment groups at 4 h and 8 h postinfection. These results provided a theoretical basis to study the application of AcMNPV-PK2-EGFP as a biological insecticide. [ABSTRACT FROM AUTHOR]

Avian virus infection remains one of the most important threats to the poultry industry. Pathogens such as avian influenza virus (AIV), avian infectious bronchitis virus (IBV), and infectious bursal disease virus (IBDV) are normally controlled by antibodies specific for surface proteins and cellular immune responses. However, standard vaccines aimed at inducing neutralizing antibodies must be administered annually and can be rendered ineffective because immune-selective pressure results in the continuous mutation of viral surface proteins of different strains circulating from year to year. Chicken T cells have been shown to play a crucial role in fighting virus infection, offering lasting and cross-strain protection, and offer the potential for developing universal vaccines. This review provides an overview of our current knowledge of chicken T cell immunity to viruses. More importantly, we point out the limitations and barriers of current research and a potential direction for future studies. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric and multiferroic ceramics of BiFeO-BaTiO-NdCoO were synthesized by a conventional solid-state reaction method and the structural, piezoelectric, multiferroic and magnetoelectric properties of the materials were investigated. All the ceramics can be well sintered at a low sintering temperature of 980 °C for 2 h. The introduction of NdCoO into BiFeO-BaTiO induces a dramatic enhancement in the piezoelectricity, multiferroicity and magnetoelectric effect of the materials. After the addition of 1.0-3.0 mol% NdCoO, the ceramics possess a morphotropic phase boundary of rhombohedral and orthorhombic phases and exhibit high Curie temperature (~486-605 °C), strong piezoelectricity, good ferroelectricity and excellent temperature stability of piezoelectricity. The greatly enhanced magnetism with M = 0.4229 emu/g and M = 2.7186 emu/g is obtained in the ceramic with 8.0 mol% NdCoO, almost six times larger than that of an undoped ceramic. The ceramic with 2.0 mol% NdCoO shows a strong magnetoelectric effect ( α = 750 mV cm Oe). The practical application potential of the present materials has also been preliminarily demonstrated by mimicking current monitoring. Our results suggest that the present ceramics may have potential applications in advanced lead-free piezoelectric and/or multiferroic devices. [ABSTRACT FROM AUTHOR]

Blue-emitting phosphors with composition (CaBa)MgSiO: yEu ( x = 0 to 0.11, y = 0.01 to 0.08) have been synthesized via a high-temperature solid-state reaction route and the effects of Mg and Eu codoping on their morphology, crystal structure, and luminescence properties were investigated. For (CaBa)MgSiO:0.04Eu, the color changed from light-blue to deep-blue region with increasing Mg content from x = 0 to x = 0.11. For (CaBa)MgSiO: yEu, the emission band showed the opposite shift with increasing y from 1% to 8%. Interestingly, increasing Mg addition led to significant reduction in the full-width at half-maximum (FWHM) from 100 nm to 70 nm. Compared with Mg-free samples, the emission intensity of the Mg-containing material with x = 0.07 was enhanced by ∼100%. The optimum doping levels of Mg and Eu were 0.07 and 0.02 for (Ca Ba)MgSiO:0.04Eu and (CaBa)MgSiO: yEu, respectively. These results indicate that such materials could be good candidate blue-emitting phosphors for use in solid-state lighting and displays. [ABSTRACT FROM AUTHOR]

A series of orange-emitting CaBi(PO): xSm phosphors were synthesized by a solid state reaction, the crystal structure and luminescent properties of the materials were studied. The doping of Sm has no obvious influence on the crystal structure of the CaBi(PO) powders and all the samples possess a cubic symmetry. Under the 401 nm excitation, the sample exhibits three typical emission bands located at 561, 598, and 644 nm corresponding to G → H, H, and H transitions, respectively. For x = 0.03, the sample exhibits an optimum luminescence. The type of energy transfer between Sm is considered as dipole-dipole interaction according to Dexter's theory. The CIE chromaticity coordinates indicate that the emission of CaBi(PO):0.03Sm locates in orange region. The results indicate that the phosphor may be used as an orange phosphor for NUV-based white LEDs. [ABSTRACT FROM AUTHOR]

Lead-free multiferroic ceramics of 0.75BiErFeO-0.25BaTiO + 1 mol% MnO were synthesized by a conventional ceramic technique, and their structure, piezoelectric, ferroelectric and ferromagnetic properties were investigated. All the ceramics possess a perovskite structure. The crystal structure of the ceramics is transformed from rhombohedral to orthorhombic phase with increasing x. The ceramics with x = 0.125-0.15 exhibit good electric insulation ( R = 2.75-2.83 × 10 Ω cm) and strong ferroelectricity ( P = 13.4-14.2 µC cm). The remanent magnetism M and saturated magnetization M of the ceramics are greatly improved by 380 and 722 % with increasing x from 0 to 0.15, respectively. The present materials exhibit strong ferroelectricity, considerable improved ferromagnetism and relatively good piezoelectricity, suggesting potential applications in advanced multiferroic devices. [ABSTRACT FROM AUTHOR]

Dy-modified KNaNbO-based lead-free piezoelectric ceramics of (KNaLi)Dy(NbTaSb)O lead-free piezoelectric ceramics were prepared by a conventional ceramics technique and the effects of Dy doping on the crystal structure, microstructure, dielectric, piezoelectric and luminescent properties of the ceramics were investigated. The ceramics with low Dy levels (x ≤ 0.015) show a pure perovskite structure, while a small amount of secondary phase DyNbO can be detected in the ceramics with x ≥ 0.02. The increase in the level of Dy doping leads to the shift of crystal structure of the ceramics from the coexistence of orthorhombic-tetragonal phases to pseudo-cubic phase. The addition of Dy inhibits the grain growth of the ceramics and induces the diffusive phase transition in the ceramics with high levels of Dy ions. The piezoelectric constant d of the ceramics decreases from 198 to 52 pC/N with x increasing from 0 to 0.03 because of the shift of the crystal structure of the ceramics from the coexistence of orthorhombic-tetragonal phase to pseudo-cubic phase. The Dy-doped ceramics excited at 453 nm have excellent luminescent properties. Two strong emission spectral bands centered at 476 and 573 nm are observed, corresponding to the transition of the F → H and F → H levels of Dy, respectively. Our study shows that the ceramic with x = 0.015 possesses simultaneously strong ferroelectricity, good piezoelectricity and excellent luminescence, suggesting that the Dy-doped ceramics may have potential application in multifunctional devices. [ABSTRACT FROM AUTHOR]

Lead-free 0.94(BiDy)NaTiO-0.06BaTiO ceramics were prepared by an ordinary sintering method and their piezoelectric and photoluminescent properties were studied. All the ceramics possess a pure perovskite structure with the coexistence of the rhombohedral and tetragonal phase. The partial substitution of Dy for Bi enhanced effectively the piezoelectricity of the materials. The optimum piezoelectricity is obtained at x = 0.025, giving d = 190 pC/N and k = 37.2 %, respectively. After the addition of Dy, excellent photoluminescence of the ceramics is induced. The Dy-doped ceramics exhibit strong emissions at ~478 nm (blue) and ~575 nm (yellow), corresponding to F → H and F → H of Dy transitions, respectively. The optimum photoluminescence of the ceramics is reached at x = 0.025. The ceramics with the doping of 2.5 mol% Dy exhibit simultaneously good piezoelectricity, strong ferroelectricity and excellent photoluminescence, suggesting a promising application in the electro-optic devices. [ABSTRACT FROM AUTHOR]

(1−x)BiFeO-xBa(BiK)TiO + 1 mol% MnO lead-free multiferroic ceramics were fabricated by a conventional ceramic technique and the effects of Ba(BiK)TiO doping and sintering temperature on the microstructure, ferroelectric, piezoelectric and ferromagnetic properties of the ceramics were studied. All the ceramics show good electric insulation with the resistivity values of 1.97 × 10-1.20 × 10 Ω cm. After the addition of Ba(BiK)TiO, two dielectric anomalies are observed at high temperatures ( T ~ 453-710 °C and T ~ 716-755 °C, respectively). The ceramic with x = 0.275 exhibits the optimum piezoelectricity ( d = 48 pC/N and k = 13.6 %, respectively). The Ba(BiK)TiO doping and the increasing in sintering temperature improve significantly the ferromagnetic properties of the ceramics. The ceramic with x = 0.25 sintered at 1,040 °C gives the optimum remnant magnetization M of 0.13 emu/g. [ABSTRACT FROM AUTHOR]

Clostridium includes a number of species, such as thermophilic Clostridium thermocellum and mesophilic Clostridium cellulolyticum, producing biofuels and chemicals from lignocellulose, while genetic engineering is necessary to improve wild-type strains to fulfill the requirement of industrialization. ClosTron system is widely used in the gene targeting of Clostridium because of its high efficiency and operability. However, the targetron plasmid present in cell hinders the successive gene disruption. To solve this problem, a pyrF-based screening system was developed and implemented in C. cellulolyticum strain H10 in this study for efficient targetron plasmid curing. The screening system was composed of a pyrF-deleted cell chassis (H10Δ pyrF) constructed via homologous recombination and a PyrF expression cassette located in a targetron plasmid containing an erythromycin resistance gene. With the screening system, the gene targeting could be achieved following a two-step procedure, including the first step of gene disruption through targetron transformation and erythromycin selection and the second step of plasmid curing by screening with 5-fluoroorotic acid. To test the developed screening system, successive inactivation of the major cellulosomal exocellulase Cel48F and the scaffoldin protein CipC was achieved in C. cellulolyticum, and the efficient plasmid curing was confirmed. With the assistance of the pyrF-based screening system, the targetron plasmid-cured colonies can be rapidly selected by one-plate screening instead of traditional days' unguaranteed screening, and the successive gene disruption becomes accomplishable with ClosTron system with improved stability and efficiency, which may promote the metabolic engineering of Clostridium species aiming at enhanced production of biofuels and chemicals. [ABSTRACT FROM AUTHOR]

Because of the success of the discrete vortex method for the simulation of large-scale vortex structure, many researchers extend this method to two-phase flow simulations, especially, to the simulation of particle dispersion in mixing layer, which is characterized by large-scale vortex structure. But the previous work is limited to one-way coupling, which neglects the effect of particles on fluid flow. In this paper, a discrete vortex method involving two-way coupling for two-phase flows is first proposed and then used in numerical simulation of two-dimensional gas-particle mixing layers. The numerical results show that the introduction of particles into the mixing layer has significant effects on the creation, development and merging process of large-scale vortex structures. It makes the mean size of large-scale vortex structure larger and the distance needed for development of large-scale vortex structure shorter. [ABSTRACT FROM AUTHOR]