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A cold adapt and ethanol tolerant endoglucanase from a marine Bacillus subtilis

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2601-2606页

作者： Dongsheng Xue Xuhao Zeng Chunjie Gong Dongqiang Lin Shanjing Yao Key Laboratory of Fermentation Engineering (Ministry of Education) Hubei Provincial Cooperative Innovation Center of Industrial Fermentation Hubei Key Laboratory of Industrial MicrobiologyHubei University of Technology Department of Chemical and Bioengineering Zhejiang University

The catalytic properties and thermodynamic kinetics of the endoglucanase from a marine Bacillus subtilis were analyzed. Optimum pH and temperature of the endoglucanase activity were 5.0 and 35 °C. The endoglucanase activity, melt point temperature was 1.13 folds(247.02 U·ml^(-1)), 2.1 °C higher(39.2 °C) in 6% ethanol solution than that(218.60 U·ml^(-1)),(37.1 °C) in free ethanol. At 40 °C–55 °C, Gibbs free energy, ΔG, and the content ofα-helix was higher in 6% ethanol solution than that in ethanol free solution. The increasing of α-helix content led to higher activity and better thermostability in ethanol solution. The cold adapt ethanol tolerant endoglucanase was valuable for bioethanol product by simultaneous saccharification and fermentation process.

关键词： Endoglucanase Ethanol tolerant cold adapt Bioethanol

Achieving strength-ductility synergy in cold spray additively manufactured Al/B4C composites through a hybrid post-deposition treatment

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Journal of Materials Science & Technology 2019年第6期35卷 1053-1063页

作者： Naeem ul Haq Tariq Lawrence Gyansah Xiang Qiu Chunnijia Hasan Bin Awais Chengwu Zheng Hao Du Jiqiang Wang Tianying Xiong Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China University of Chinese Academy of Sciences Beijing 100049 China Department of Metallurgy and Materials Engineering Pakistan Institute of Engineering and Applied Sciences Nilore Islamabad Pakistan School of Materials Science and Engineering University of Science and Technology of China Shenyang 710016 China

cold spray additive manufacturing(CSAM) provides a potential solid state manufacturing route to fabricate variety of aluminum matrix composites(AMCs) with reduced possibility of undesired chemical reactions and residual thermal stresses. This study presents a hybrid(i.e. hot compression + hot rolling)post-deposition treatment to reinvigorate the mechanical properties of cold spray additively manufactured Al/B4 C composites. The as-deposited samples were initially subjected to 30% thickness reduction via hot compression treatment at 500°C followed by a hot rolling treatment with 40% thickness reduction in 2 passes. Electron backscatter diffraction(EBSD) and high resolution transmission electron microscopy(HRTEM) results revealed that after hybrid post-deposition treatment(involving 70%accumulative thickness reduction), the aluminum grains in the matrix were extensively refined due to simultaneous operation of continuous dynamic recrystallization(CDRX) and geometric dynamic recrystallization(GDRX). Furthermore, interfacial defects were remarkably reduced while the nature of Al/Al and Al/B4C interfacial bonding was changed from sheer mechanical interlocking to metallurgical bonding which facilitated efficient transference of applied load to uniformly dispersed bimodal B4C particles. As a result, ultimate tensile strength(UTS) and elongation(EL) of the as-deposited sample were simultaneously improved from 37 to 185 MPa and 0.3% to 6.2%, respectively.

关键词： cold spray additive manufacturing Post-deposition treatments Al/B4C composites Dynamic recrystallization Mechanical properties

Synthesis and properties of SrFe_(12)O_(19) obtained by solid waste recycling of oily cold rolling mill sludge

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 642-648页

作者： Bo Liu Shen-gen Zhang Britt-Marie Steenari Christian Ekberg Institute for Advanced Materials and Technology University of Science and Technology Beijing Nuclear Chemistry and Industrial Material Recycling Department of Chemistry and Chemical Engineering Chalmers University of Technology

The aim of this study was to develop a new approach for the preparation of environmentally friendly, high-value products from oily cold rolling mill(CRM) sludge. Utilizing oily CRM sludge as a source of iron, strontium hexaferrite(SrFe_(12)O_(19)) powders were prepared by multi-step processes involving acid leaching, chemical conversion treatment, and synthesis by a citrate precursor. The influences of citric acid dosage and the pH of the sol system on the formation, crystallite size, and magnetic properties of the obtained SrFe_(12)O_(19) powders were investigated. High saturation magnetization(74.8 mA·m^2·g^(–1)) and intrinsic coercivities(614.46 mT) were achieved for pH 7.0 of the sol system, for which the molar ratio of citric acid dosage to the total dosage of Fe^(3+) and Sr^(2+) was 1.5. This study presents a new approach to utilizing oily CRM sludge, and even refractory iron-containing solid waste.

关键词： strontium ferrite oily cold rolling mill sludge magnetic properties citrate precursor method recycling

Application of hopcalite catalyst for controlling carbon monoxide emission at cold-start emission conditions

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Journal of Traffic and Transportation Engineering(English Edition) 2019年第5期6卷 419-440页

作者： Subhashish Dey Ganesh Chandra Dhal Devendra Mohan Ram Prasad Department of Civil Engineering Indian Institute of Technology (Banaras Hindu University) Varanasi 221005 India Department of Chemical Engineering and Technology Indian Institute of Technology (Banaras Hindu University) Varanasi 221005 India

Carbon monoxide(CO) is a poisonous gas particularly to all leaving being present in the atmosphere.An estimate has shown that the vehicular exhaust contributes the largest source of CO pollution in developed countries.Due to the exponentially increasing number of automobile vehicles on roads,CO concentrations have reached an alarming level in urban areas.To control this vehicular exhaust pollution,the end-of-pipe-technology using catalytic converters is recommended.The catalysts operating efficiently in a catalytic converter are a challenging class of materials for applications in cold start of engines to maintain indoor air quality.In the cold start period,the catalytic converter was entirely inactive,because the catalytic converter had not been warmed up.The cold start phase is also depending upon the characteristics of vehicles and property of catalysts.The increasing cost of noble metals with the increasing number of vehicles motivates the investigation of material concepts to reduce the precious metal content in automotive catalysts or to find a substitute for noble metals.Hopcalite(CuMnOx) catalyst could work very well at the low temperature;thus,it can overcome the problem of cold-start emissions if used in a catalytic converter.Further,low cost,easy availability and advanced synthesis methods with stabilizer,promoter,etc.,advocates for the use of hopcalite as an auto exhaust purification catalyst.Although there are numerous research articles present on this topic until now,no review has been presented for demanding this issue.So there is a space in this area,and it has been made an attempt to seal this hole and progress the future scope for hopcalite catalyst for purification of exhaust gases by this review.

关键词： Automobile vehicle Hopcalite catalyst Catalytic converter applications cold start emission Carbon monoxide

Experimental characterization of the 3D linear viscoelastic behavior of cold recycled bitumen emulsion mixtures

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Journal of Traffic and Transportation Engineering(English Edition) 2019年第4期6卷 324-336页

作者： Andrea Graziani Carlotta Godenzoni Francesco Canestrari Dipartimento di Ingegneria Civile Edile e Architettura Università Politecnica delle Marche

cold mixtures with bitumen emulsion are produced at ambient temperature, leading to substantial reductions of energy consumption and atmospheric emissions. In cold recycling applications, cement is normally used to improve the mixture performance. Thus, the rheological behavior of cold recycled mixtures is different from that of conventional hot mixtures because it is due to the interaction of fresh bitumen, aged bitumen and cementitious bonds. In this study, we investigated the three-dimensional(3 D) linear viscoelastic(LVE) behavior of a cement-bitumen treated material(CBTM) mixture fabricated using bitumen emulsion and cement. For comparison, we also investigated the 3 D LVE behavior of hot-mix asphalt containing 25% of reclaimed asphalt and fabricated using polymermodified binder. Sinusoidal axial tests on cylindrical specimens, were carried out at various temperatures(from 0℃ to 50℃) and frequencies(from 0.1 to 12 Hz). The complex Young’s modulus E~*and the complex Poisson’s ratio v~*were determined through the measurement of axial and transverse strain. We show that when considering E*, CBTM mixtures may be considered thermo-rheologically simple and the Huet-Sayegh model can be used to simulate the frequencyetemperature dependence. On the other hand, when considering v*the behavior of CBTM mixtures is very different from that of hot mix asphalt. In particular, its absolute value is almost constant and very close to 0.15.

关键词： Bitumen emulsion cold recycling Complex modulus Complex Poisson’s ratio Huet-Sayegh model

cold acclimation improves photosynthesis by regulating the ascorbate–glutathione cycle in chloroplasts of Kandelia obovata

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Journal of Forestry Research 2019年第3期30卷 755-765页

作者： Weicheng Liu Chunfang Zheng Jinong Chen Jianbiao Qiu Zhixing Huang Qi Wang Yong Ye Zhejiang Key Laboratory of Exploitation and Preservation of Coastal Bio-resource Zhejiang Mariculture Research Institute325005 WenzhouPeople’s Republic of China College of Life and Environmental Science Wenzhou University325035 WenzhouPeople’s Republic of China Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem College of the Environment and EcologyXiamen University361005 XiamenPeople’s Republic of China

As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to determine the resistance of K. obovata seedlings to low temperature stress by cold acclimation and to explain the mechanisms for alleviating cold injury. To understand these mechanisms, seedlings that were acclimatized and not acclimatized were exposed to 5℃/- 2℃(day/night)for 48 h.Results showed that low temperature stress reduced leaf photosynthesis of non-acclimatized seedlings by inducing oxidative stress and structural damage to chloroplasts. These phenomena were shown by increasing levels of malondialdehyde (MDA), O2-and H2O2, as well as decreasing enzyme activities in the ascorbate–glutathione (AsA-GSH) cycle. However, cold-acclimatized seedlings had improved photosynthetic rates and efficiency of photosystem II (PSII) under low temperature stress. Compared with non-acclimatized seedlings, leaves of coldacclimatized seedlings under low temperature stress for 48 h exhibited higher anti-oxidative enzyme activities, lower levels of O2^- and H2O2, less damage to chloroplast structure, and removed 33.7% of MDA at low temperature stress for 48 h. The data indicate that cold acclimation enhances photosynthetic capacity by effectively regulating activation in the PSII electron transport and the AsA–GSH cycle to scavenge excess ROS in chloroplasts, while the latter is more important.

关键词： Ascorbate–glutathione cycle cold acclimation Kandelia obovata Photosynthesis

cold plumes trigger contamination of oceanic mantle wedges with continental crust-derived sediments:Evidence from chromitite zircon grains of eastern Cuban ophiolites

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Geoscience Frontiers 2018年第6期9卷 1921-1936页

作者： J.A.Proenza J.M.González-Jiménez A.Garcia-Casco E.Belousova W.L.Griffin C.Talavera Y.Rojas-Agramonte T.Aiglsperger D.Navarro-Ciurana N.Pujol-Solà F.Gervilla S.Y.O’Reilly D.E.Jacob Departament de Mineralogia Petrologia i Geologia AplicadaUniversitat de BarcelonaC/Martíi Franquès s/n08028BarcelonaSpain Departamento de Mineralogía y Petrología Universidad de GranadaFacultad de CienciasFuentenueva s/n 18002GranadaSpain Instituto Andaluz de Ciencias de la Tierra(CSIC-UGR) Avda.de las Palmeras 4E-18100ArmillaGranadaSpain ARC Centre of Excellence for Core to Crust Fluid Systems(CCFS) GEMOC National Key CentreDepartment of Earth and Planetary SciencesMacquarie UniversitySydneyNSW 2109Australia John de Laeter Centre Curtin UniversityPerthWA 6102Australia Geocycles-Earth System Research Center Institut fur GeowissenschaftenJohannes Gutenberg-UniversitatBecherweg 21D-55099 MainzGermany Departamento de Geociencias Universidad de los AndesBogotáColombia

The origin of zircon grains, and other exotic minerals of typical crustal origin, in mantle-hosted ophiolitic chromitites are hotly debated. We report a population of zircon grains with ages ranging from Cretaceous(99 Ma) to Neoarchean(2750 Ma), separated from massive chromitite bodies hosted in the mantle section of the supra-subduction(SSZ)-type Mayari-Baracoa Ophiolitic Belt in eastern Cuba. Most analyzed zircon grains(n = 20, 287 ± 3 Ma to 2750 ± 60 Ma) are older than the early Cretaceous age of the ophiolite body, show negativeε_(Hf)(t)(-26 to-0.6) and occasional inclusions of quartz, K-feldspar,biotite, and apatite that indicate derivation from a granitic continental crust. In contrast, 5 mainly rounded zircon grains(297±5 Ma to 2126±27 Ma) show positive εHf(t)(+0.7 to +13.5) and occasional apatite inclusions, suggesting their possible crystallization from melts derived from juvenile(mantle)sources. Interestingly, younger zircon grains are mainly euhedral to subhedral crystals, whereas older zircon grains are predominantly rounded grains. A comparison of the ages and Hf isotopic compositions of the zircon grains with those of nearby exposed crustal terranes suggest that chromitite zircon grains are similar to those reported from terranes of Mexico and northern South America. Hence, chromitite zircon grains are interpreted as sedimentary-derived xenocrystic grains that were delivered into the mantle wedge beneath the Greater Antilles intra-oceanic volcanic arc by metasomatic fluids/melts during subduction processes. Thus, continental crust recycling by subduction could explain all populations of old xenocrystic zircon in Cretaceous mantle-hosted chromitites from eastern Cuba ophiolite.We integrate the results of this study with petrological-thermomechanical modeling and existing geodynamic models to propose that ancient zircon xenocrysts, with a wide spectrum of ages and Hf isotopic compositions, can be transferred to the mantle wedge above subducting slabs by cold plumes.

关键词： Zircon U-Pb geochronology Chromitites cold plumes Ophiolites Cuba

Correlating particle impact condition with microstructure and properties of the cold-sprayed metallic deposits

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Journal of Materials Science & Technology 2020年第5期40卷 185-195页

作者： Yujuan Li Yingkang Wei Xiaotao Luo Changjiu Li Ninshu Ma State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an710049China Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan

Inter-particle bonding is an important factor affecting the property of cold sprayed metallic deposit.Because the interface bonding between particles in deposit is directly determined by plastic strain of particles during spraying,Cu deposits were made at series of impact velocities of 578 m s^-1 to 745 m s^-1 and 807 m s^-1 to correlate particle impact condition with microstructure and properties of the deposits.Results show that as the average particle impact velocity increases from 578 m s^-1 to 745 m s^-1 and 807 m s^-1,the deposition efficiency of feedstock powder increases from 58%to 84%and even to 95%.Although all three deposits reveal dense microstructure due to the high ductility of Cu,the deformation degree of the deposited particles remarkably increases with increasing impact velocity.The enhanced plastic deformation of the deposited particles leads to more dispersed oxide scale and thereby stronger interparticle bonding with the strength of the deposit along the deposition direction increasing from 25.8 MPa to 148.5 MPa.The electrical and thermal conductivities at through-thickness direction of the deposit at particle impact velocity of 807 m s^-1 are 78%IACS,295 W m^-1 K^-1,respectively.

关键词： cold spray Particle impact velocity Deposition efficiency Electrical conductivity Thermal conductivity Mechanical property

Microstructure and Corrosion Behavior of Friction Stir Welded Al Alloy Coated by In Situ Shot-Peening-Assisted cold Spray

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 172-182页

作者： Hua Zhang Chang-Yu Zhao Qi-Long Guo Rui-Sheng Yang Li-Yuan Liu San-Bao Lin School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Institute of Astronautical Systems and Engineering Beijing 100076China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

To improve the corrosion resistance of friction stir welded(FSW)joints,in situ shot-peening-assisted cold spray coating was applied to the surface of FSW joints.The microstructure and corrosion behavior of the coatings were investigated.The results showed that a dense coating was obtained by cold spraying technology.Moreover,the use of in situ shot-peeningassisted technology significantly reduced the porosity of the coating,which has a positive impact on the microstructure and the mechanical performance.Exfoliation corrosion tests showed that the coating aff ected positively on the corrosion resistance.On the coated surface,the craters caused by shot-peening particles were corroded in the form of exfoliation corrosion,while the exposed particles were corroded in the form of intercrystalline corrosion.This work provides a new approach to the corrosion protection of FSW joints.

关键词： Aluminum alloy coating cold spray Friction stir welding In situ shot-peening Intergranular corrosion