Microstructure and mechanical properties of E36 steel joint welded by underwater wet welding

The microstructure and mechanical properties of E36 steel joint welded by underwater welding using flux-cored wire are comprehensively investigated. The welding depth, welding current and welding voltage is 4 m, 130 A and 32 V, respectively. The weld metal is ferrite which varies in size, with carbide particles distributed on it, while the microstructure of HAZ is mixture of martensite of different size and some tempered structure. The microhardness of the weld metal is 190 HV. Almost all the tensile specimens fracture in weld metal and the average tensile strength of joint is 390 MPa, which is equal to 80% that of base metal. The tensile fracture morphology of joint presents obviously the characterization of brittle fracture, which displays the features of cleavage fracture and intergranular fracture.

Microstructure evolution of HAZ in the multi-pass underwater wet welded joints

The microstructure evolution of heat-affected zone （HAZ） in the multi-pass underwater welded joints is investigated in the present work, and it can be characterized by four zones, marked as Region A, B, C and D, respectively. The microstructure in Region A is the mixture of lath martensite and residual austenite. Besides this structure, lots of acicular ferrite appears in Region B as well, and the grain size becomes larger. Lath ferrite combined with granular bainite is observed in Region C. In Region D, tempered sorbite, granular bainite and fine acicular ferrite are found within the grains, while massive ferrite and Widmanstatten structure are distributed along the grain boundary： The thermal effect of multi-pass welding makes the microstructure and property more and more uniform in the ttAZ, and the largest hardness 356 HV in the HAZ appears in Region A.

Effect of Zn^(2+) Ions on Upconversion Emission of Er^(3+) in Zn/Er:LiNbO_3 Crystal

The effect of Zn 2＋ ions codoped on the upconversion emission of Er 3＋ ions in Er：LiNbO 3 crystal under different excitation wavelength was reported.The upconversion emission spectra of Zn/Er：LiNbO 3 following 800 nm excitation reveal an enhanced green emission and a suppressed red emission simultaneously.The cross relaxation processes（2 H11/2 ＋ 4 I13/2 → 4 I11/2 ＋ 4 F9/2 and 4 F7/2 ＋ 4 I11/2 → 4 F9/2 ＋ 4 F9/2） are responsible for populating the red 4 F 9/2 emitting state.The dissociation effect of Zn2＋ ions on the Er 3＋ cluster sites makes these cross relaxation processes inefficient.Under 980 nm excitation,the Zn 2＋ codoped leads to the decreased intensities of green and red upconversion emissions.These reductions are attributed to the inefficient cross relaxation processes（4 I11/2 ＋ 4 I11/2 → 4 F7/2 ＋ 4 I15/2 and 4 F7/2 ＋ 4 I11/2 → 4 F9/2 ＋ 4 F9/2） caused by the same dissociation effect of Zn 2＋ ions.

Identification and evolution of interfacial structure of SiO2 glass ceramic/Ti-6AI-4V alloy joint bonded with AgCu/Ni interlayer

AgCu/Ni composite interlayer was utilized to join SiO2 glass ceramic （74. 52% SiO2-23. 40% Al2 03 -2. 08 % K2 O, wt. % ） and Ti-6Al-4V alloy by eutectic reaction. Interface structures of the joints were identified by means of TEM analysis. This joining method contains three characteristic processes, which are the melting of AgCu eutectic alloy, eutectic reaction between interlayer and Ti-6Al-4V base material and active reaction of element Ti to SiO2 glass ceramic. It is different from traditional active brazing because active element Ti totally dissolves from Ti-6Al-4 V and reacts with SiO2 glass ceramic. SiO2 glass ceramic can be joined suecessfuUy to Ti-6Al-4 V alloy by this novel bonding method and the joint exhibits high shear strength, up to 110 MPa.

Synthesis, Structure, and Photoluminescence Property of a Novel One-dimensional Inorganic-organic Hybrid Gallophosphate JGP-2

A novel one-dimensional inorganic-organic hybrid gallophosphate compound, Ga（2,2＇-bipy）（HPO4）. （H2PO4）（denoted JGP-2） was synthesized hydrothermally with 2,2＇-bipyridine as a ligand and characterized by X-ray powder diffraction （XRD）, elemental analysis, inductively coupled plasma（ICP）, TGA analysis, solid-state ^31p NMR, and luminescence spectra and structurally determined by single-crystal X-ray diffraction analysis. JGP-2 crystallized in the triclinic system, space group P^-1（No.2）, with a=0.7818（1） nm, b=0.8611 （2） nm, c=1.0908（2） nm, V=0.6727（2） nm^3 and Z=2 with R1=0.0223. The structure of JGP-2 was built up by alternate arrangement of GaO4N2 octahedra, and HPO4（or H2PO4） tetrahedra to form an infinite one-dimensional corner-sharing-corner（CSC） chain. Through P sites, the CSC chains link with an unusual edge-sharing dimmer, Ga2F4（H2O）2, giving rise to a 4,10-membered ring net layered structure of JGP-7. On excitation at 254 nm, JGP-2 can emit strong blue light at ,λmax=388 rim. JGP-7 presents a strong fluorescence emission band centered at 394 nm（λex=340 nm）, the emission energy of JGP-7 is red-shifted comoared with that of JGP-2.

CuO-containing multi-walled carbon nanotubes:a novel catalyst for the catalytic ozonation of humic acid in water

CuO particles were attempted to fill in the channel of multi-walled carbon nanotubes (MWCNTs) as novel catalytic materials CuO@MWCNTs used for ozonation of humic acids (HA) in aqueous solution.Catalyst samples were characterized by transmission electron microscopy (TEM),X-ray diffraction (XRD),thermogravimetric analysis (TG) and X-ray photoelectron spectroscopy (XPS).The removal efficiency of HA was promoted in the presence of CuO@MWCNTs compared with that of Al2O3-supported CuO catalyst (CuO/Al2O3) and CuO-coating MWCNTs catalyst (CuO/MWCNTs).The strong synergetic effect in the confinement environment on CuO nanoparticles can attribute to the locally higher pressure due to the lower potential energy of reactants in the channels.Strong interaction happened between the catalyst and reactants,which promoted the decomposition of ozone and the generation of OH.The results of experimental and theoretical investigation confirmed that CuO@MWCNTs promotes the initiation and generation of OH,hence accelerating the degradation of organic pollutants.

Syntheses,Crystal Structures and Luminescent Properties of Three New Gallium Complexes Containing Pyridine-2,6-dicarboxylic Acid

Three new gallium complexes formulated as [Ga（PDA）2 ][Ga（H2O）（PDA）（phen）]·4H2O（1）,[Ga（PDA） 2]·（H2IN）·2H2O（2） and [Ga（OH）（PDA）（H2O）] 2（3）（H2PDA=pyridine-2,6-dicarboxylic acid;phen=1,10-phenanthroline;HIN=isonicotinic acid） have been synthesized under hydrothermal conditions.In the mixed-ligand system of complex 1,PDA2 and phen are connected to the central Ga 3＋ cation as tri-and bi-dentate ligands,respectively.In complex 2,each Ga 3＋ cation is six-coordinated by two PDA 2 anions octahedrally.Complex 3 shows a binuclear structure,with the bond distance of Ga1― Ga2 being 0.30061（3） nm.The 3D supramolecular structures of the three complexes are constructed via hydrogen bonds and aromatic π-π packing interactions.All the three complexes exhibit intense blue emission at room temperature in the solid state,which are attributed to π＊-π transition centered on the ligands.

Behaviors of interfacial elements during the brazing of SiO2 glass ceramic to Ti-6AI-4V with AgCu/Ni interlayer

AgCu/Ni composite interlayer was used to join SiO2 glass ceramic to Ti-6AI-4V alloy successfully, obtaining the largest joint shear strength 110 MPa. Ag, Cu and Ni in the interlayer and Ti in the Ti-6AI-4V alloy affect the joint formation and interfacial products significantly. To understand the joint formation process better, behaviors of elements Ag, Cu, Ni and Ti during the brazing of SiO2 glass ceramic to Ti-6AI-4 V alloy were investigated in the present work. Active element Ti is the most important component in the joining, realizing the metallurgical bonding of SiO2 glass ceramic to braze alloy. Cu together with Ni reacts to Ti in the base material by Ti-Cu-Ni ternary eutectic reaction, which is beneficial for reducing the massive Ti- Cu and/or Ti-Ni brittle intermetallic compounds on the joint interface. Dispersion of Ag decreases the brittleness qf the whole joint effectively.

Nature of DNA-graphene Interaction System: An Theoretic Account

The nature of DNA-graphene interaction system was investigated by using molecular dynamic simulations and density functional theory calculations. The detailed adsorption behaviors of single-stranded DNA( ssDNA) and double-stranded DNA( dsDNA) on the surface of graphene were discussed. The π-π stacking would contribute to the maximum average loading of ssDNA( 167 segments) with the adsorption potential distribution at the range of-6. 0 eV to-2. 1 eV,higher than that of dsDNA( 30 segments) with the adsorption energy distribution ranging from-3. 0 eV to- 0. 2 eV. Gradually shielding the base of ssDNA using hydrogen atom and gradually changing ssDNA into dsDNA through base-pairing were performed to further detect the detailed interaction between DNA and graphene. E B for * CGC,G* GC,GC* C,and GCG* is-15. 130,-15. 276,-15. 137,and- 15. 271 eV,respectively. E B for GCGC-CGCG / graphene,GCGC-CGC / graphene,GCGC-CG / graphene,GCGC-C / graphene,and GCGC / graphene is-14. 941,-14. 700,-14. 204,-15. 561,and- 15. 810 eV,respectively. DOS of the adsorbed ssDNA down shifted 1. 885 eV,which becomes more stable and less reactive than the other cases. Further,oxidation reaction shows that graphene protects ssDNA from breaking by active oxide. And stable adsorption,protection from destroying,and undamaged desorption insure the possibility of graphene to deliver or hybrid DNA for novel and creative use.

Packing Structures of Thiophene Dimers and Their Effects on Excitation Energies of Thiophene Dimers

The packing structures of thiophene dimers and their effects on excitation energies of thiophene dimers were studied by employing MP2/6-31 ＋ G^＊ and TDDFT calculations. Twelve Optimized dimers with different orientations were obtained by means of MP2/6-31 ＋ G ^＊ optimizations. Among them, five T-shaped and three π-stacked thiophene dimers are local minima in energy. The result shows that the preferable conformation of thiophene dimers is the T- shaped packing, which is in agreement with the results in references. All the excitation energies of both T-shaped dimers（5. 34-5. 48 eV） and π-stacked dimers（5. 15-5. 18 eV） are lower than that of the isolated thiophene（5.68 eV）, indicating that inter-ring interactions decrease the excitation energies.

Anomalies of Doped-LiNbO_(3) Crystal in Photorefractive Phase Conjugation with Relation to Structural Phase Transformation

We investigate the photorefractive phase conjugation in a Ce:Fe:LiNbO_(3) crystal asa function of temperature(293-393 K)and find the phase conjugate reflectivity in-creases sharply in the vicinity of 55,70 and 110℃.The anomalous phenomenon ispossibly concerned with the structural phase transformation of a crystal,which in-duces an extra internal electric ficld to influence the phase conjugation.The value ofthe field is estimated at the order of 10^(5)V/m,in agreement with the published data.

The Influence Factors Analysis to Improve the Compatibility and the Mechanical Behavior of IPN, Gradient IPN and BaTiO₃Filled IPN

Interpenetrating polymer network (IPN), gradient IPN and BaTiO3 filled IPN, composed of poly(ethylene glycol urethane) (PEGPU) and unsaturated polyester resin (UP) curing at room temperatures were prepared. Then the effect of soft/hard segment ratio in polyurethane (PU), component ratio of PU to UP in IPN, adding amount of BaTiO3 in filled IPN, the component sequences and interval times between each IPN for gradient IPN, on morphology and mechanical behavior of IPN and BaTiO3/IPN nanocomposites with different molecular weight of PU were studied systematically. Moreover, the investigation on the relationship between the morphologies and the mechanical properties indicated that the IPN with finer morphology exhibited an excellent consistency of the higher strengths and elongations.

Recent advances in rare-earth elements modification of inorganic semiconductorbased photocatalysts for efficient solar energy conversion: A review

This review focused on rare-earth elements containing inorganic semiconductor photocatalysts for efficient solar energy conversion. We also summarized the recent progress in the modification of the transition metal oxides and mixed oxides with rare earth ions. In the first section, we surveyed a variety of rare-earth elements modified TiO2 photocatalysts. Attributed to the modifica-tion with rare-earth elements, phase transformation of TiO2 from anatase to rutile was inhibited. Furthermore, the light-absorbing property of the TiO2 modified with rare-earth elements was also enhanced. In the second section, we summarized the effects of rare-earth elements on the modification of transition metal mixed oxides. It was believed that the corner-shared octahedral units in the form of networks, chains and slabs within the mixed oxide lattice were essential for the enhancement of the photocatalytic activity. In the last section, the strategy for the design of NIR or IR response upconversion composite photocatalysts was also discussed.

Effects of the penetration temperature on structure and electrical conductivity of samarium modified BaTiO_3 powders

Gaseous penetration technique was adopted to improve the electrical conductivity of BaTiO3 powders and the effects of penetration temperature on the structure and electrical conductivity of Sm-modified BaTiO3 powders were studied.It was observed that the penetration of Sm made the resistivity of BaTiO3 powders decrease with the increase in the penetration temperature and decreased to the lowest point of 4.20×102 ？·m when the penetration temperature was 950 oC.The relationship curve of the temperature and resistivity of the samples was also established preliminarily to get the mathematical expression by the fitting method.Through X-ray diffraction （XRD） analysis,the new phases of Sm2O3 and Ba4Ti2O27 were detected.It was indicated that intricate reactions related to Sm took place during the penetration process and led to the Ti-rich state of the system.The Fourier transform infrared （FTIR） spectrum illustrated that the bonds of Ti–O octahedron was strengthened by substitution of Sm3＋ at Ti4＋ sites,which led to the growth of Ti：Ba ratio.The analysis results of scanning electron microscopy （SEM） indicated that the particle size of Sm-modified BaTiO3 powders progressed with the penetration temperature increasing.

TEMPERATURE DEPENDENCE OF TWO-BEAM COUPLING IN Ce: LiNbO_3 CRYSTAL

The effect of temperature on photorefractive process is a significant problem inphotorefractive nonlinear optics. The temperature dependence of photoretiactive effect in semiinsulating semiconductive material Cr: GaAs was investigated by CHENG Li-jen et al., and they thought that the band gap of conventional oxide photorefractive crystal was too wide, so it is difficult to observe the temperature dependence of photorefractive effect in a general experimental condition. But the point of view has been proved not true by our experiment

Fe_3O_4 Nanoparticles Decorated Multi-walled Carbon Nanotubes and Their Sorption Properties

This paper reports a simple and efficient chemical method to decorate multi-walled carbon nano- tubes（MWCNTs） with iron oxide nanoparticles. The TEM, FTIR, Raman and UV analysis demonstrate that iron oxide nanoparticles were well deposited on the outer walls of MWCNTs. The size of the nanoparticles ranges from 30 to 50 nm. The sorption property of MWCNTs/Fe3O4 composites for the removal of 2,4-dichlorophenol（2,4-DCP） and Cu2＋ ions from aqueous solution was explored. The results present that MWCNTs decorated with Fe3O4 possessed higher sorption capability for removing 2,4-DCP and Cu2＋ ions, which favour the highly potential applications for pollutants removal from water.

Inhibitory effect of H_(3+x)PMo_(12-x)V_xO_(40)-Ton the self-polymerization of methyl methacrylate

In this work,a series of molybdovanadophosphoric heteropoly acid quaternary ammonium salts H_（3＋x）PMo_（12 -x）V_xO40-T were synthesized and employed as a reaction inhibitor in the selfpolymerization of methyl methacrylate（MMA）.The polymerization inhibition effect of H_（3＋x）PMoPMo_（12 -x）V_xO40-T）with different number of vanadium atoms and reaction dosages was investigated using differential scanning calorimetry（DSC）.It shows that the inhibitory effect was improved with the increasing dosages of H_（3＋x）PMoPMo_（12 -x）V_xO40-T）,and the polymerization inhibition was also affected by the number of vanadium atoms in the H_（3＋x）PMo_（12 -x）V_xO40-T .Furthermore,cyclic voltammograms（CV）was used to probe the mechanism of the inhibition reaction with H3＋xPMo12xVxO40-T.The result of CV indicates that the inhibition reaction is an oxidation–reduction reaction.H_（3＋x）PMo_（12 -x）V_xO40-T can react directly with the MMA monomer radicals,which eliminated the MMA monomers,and therefore the self-polymerization of the MMA can be effectively inhibited by H_（3＋x）PMo_（12 -x）V_xO40-T.

自清洁钙钛矿型催化剂用于甲烷干气重整(英文)

Gas-to-liquid processes are generally used to convert natural gas or other gaseous hydrocarbons into liquid fuels via an intermediate syngas stream. This includes the production of liquid fuels from biomass‐derived sources such as biogas. For example, the dry reforming of methane is done by reacting CH4 and CO2, the two main components of natural biogas, into more valuable products, i.e.,CO and H2. Nickel containing perovskite type catalysts can promote this reaction, yielding good conversions and selectivities; however, they are prone to coke laydown under certain operating conditions. We investigated the addition of high oxygen mobility dopants such as CeO2, ZrO2, or YSZ to reduce carbon laydown, particularly using reaction conditions that normally result in rapid cok‐ing. While doping with YSZ, YDC, GDC, and SDC did not result in any improvement, we show that a Ni perovskite catalyst (Na0.5La0.5Ni0.3Al0.7O2.5) doped with 80.9 ZrO2 15.2 CeO2 gave the lowest amount of carbon formation at 800 °C and activity was maintained over the operating time.

Enhanced performance of ruthenium dye-sensitized solar cell by employing an organic co-adsorbent of N,N'-bis((pyridin-2-yl)(methyl)methylene)-o-phenylenediamine

A pyridine-anchor co-adsorbent of N,N＇-bis（（pyridin-2-yl）（methyl） methylene）-o-phenylenediamine（named BPPI） is prepared and employed as co-adsorbent in dye-sensitized solar cells（DSSCs）. The prepared co-adsorbent could overcome the deficiency of N719 absorption in the low wavelength region of visible spectrum, offset competitive visible light absorption of I_3^-, enhance the spectral responses of the co-adsorbed TiO_2 film in region from 300 nm to 750 nm, suppress charge recombination, prolong electron lifetime, and decrease the total resistance of DSSCs. The optimized cell device co-sensitized by BPPI/N719 dye gives a short circuit current density of 12.98 m A cm^（-2）, an open circuit voltage of 0.73 V,and a fill factor of 0.66 corresponding to an overall conversion efficiency of 6.22% under standard global AM 1.5 solar irradiation, which is much higher than that of device solely sensitized by N719（5.29%）under the same conditions. Mechanistic investigations are carried out by various spectral and electrochemical characterizations.

Green Upconversion Luminescence in Er^(3+)/Yb^(3+) Codoped CaWO_(4) Polycrystals

CaWO_(4) polycrystals with fixed Yb^(3+)and various Er^(3+)concentrations are synthesized via the high temperature solid state method.The crystal structure of the polycrystals is characterized by means of x−ray diffraction.The upconversion properties of the polycrystals under the 980 nm excitation are investigated.Intense emission bands centered at 530 nm and 552 nm correspond to the transitions ^(2)H_(11/2)→^(4)I_(15/2) and ^(4)S_(3/>2)→^(4)I_(15/2 )of Er3+,respectively.The dependence of intensity of the green emission on the pump power and possible upconversion mechanism are discussed.Quantitative analysis of dependence of upconversion emission intensity on the pump power of a laser diode indicates that two-photon processes are responsible for both 530 nm and 552 nm green upconversion emissions.