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Non-equilibrium solidification and experienced thermal conditions of deposited 2219 aluminium alloy during wire and arc additive manufacturing (WAAM) result in the grain boundary segregation, which makes it difficult to avoid the appearance of columnar grain. In this work, columnar crystal defects and grain boundary segregation were eliminated by adding TiC nanoparticles (TiCnps) to WAAM-deposited 2219 aluminium alloy. The effects of TiCnps addition on the solidification dynamics, particles distribution, grain boundary structure, solute redistribution, and mechanical properties were investigated. The solidification dynamics of the droplet induced by mesoscopic TiC particles was assessed and the result showed that the addition of c. 80 nm TiCnps could reduce the solid–liquid growth rate (R), besides, the critical movement rate (Rc) of 80 nm TiCnps was much lower than that of R, i.e. TiCnps were inclined to be distributed inside the grains as effective nucleation particles. Micro-pools with multi-site nucleation inhibited grain boundary segregation and increased Cu concentration in Al-matrix. Such a variation in Cu atom concentration promoted the precipitation of the fine spot-like θ′-CuAl2 phase with a diameter of c. 500 nm, besides, the dendritic θ-CuAl2 phase along the grain boundary was all transformed into α-Al+θ-CuAl2 phases with a semi-coherent state. The fine spot-like phase and TiCnps possessed a strong interfacial bonding with the Al-matrix, thereby the mechanical properties of the deposited 2219 aluminium alloy were strengthened. Eventually, the deposited 2219 aluminium alloy with the addition of TiCnps exhibited excellent mechanical properties, i.e. the tensile strength of the samples were around 380 MPa, and the elongation could be up to 21.4%.

The neurovascular unit (NVU) reflects the close temporal and spatial link between neurons and blood vessels. However, the understanding of the NVU in the spinal cord is far from clear and largely based on generalized knowledge obtained from the brain. Herein, we review the present knowledge of the NVU and highlight candidate approaches to investigate the NVU, particularly focusing on the spinal cord. Several unique features maintain the highly regulated microenvironment in the NVU. Autoregulation and neurovascular coupling ensure regional blood flow meets the metabolic demand according to the blood supply or local neural activation. The blood–central nervous system barrier partitions the circulating blood from neural parenchyma and facilitates the selective exchange of substances. Furthermore, we discuss spinal cord injury (SCI) as a common injury from the perspective of NVU dysfunction. Hopefully, this review will help expand the understanding of the NVU in the spinal cord and inspire new insights into SCI.

To obtain excellent spreadability under lower heat input and optimize interfacial microstructure, the spreading limited factors were analysed in wetting of liquid CuSi3 on 304ss and TC4 plates. At the CuSi3/TC4 joining side, the spreading model changed from diffusion-limited to reaction-limited with the interfacial temperature decreases which caused by the decrease of heat input. In the reaction-limited spreading, a continuously thin reaction layer (∼61 μm) was observed, consisting of Cu + Ti2Cu3 + TiCu4 + Ti5Si3, and TiCu + Ti2Cu + Ti5Si3. In the diffusion-limited spreading, a thin reaction layer was transformed to a thick (∼125 μm) one with intricate phases, containing primarily of Ti5Si3 + TiFe2+Ti2Cu3 + TiCu4, Ti5Si3 + TiCu + AlCu2Ti, and TiCu + Ti2Cu therein. The spreading energy provided by the interfacial reaction (26 kJ/mol) was higher than that provided by the diffusion of Ti atoms in copper (21 kJ/mol), i.e. the spreading rate under 65 A welding current with a 0.783 KJ/cm heat input was greater than that under 70 A with a 0.853 KJ/cm heat input. The rapid spreading with a short residence time at a high temperature could reduce the thickness of the interface layer. At the CuSi3/304ss joining side, CuSi3 droplet could not wet 304ss when the heat input was lower than 0.783 KJ/cm. The wettability was gradually improved with increasing heat input, and the spreading driving force was provided by the diffusion of Fe in liquid Cu. A typical solid solution interface without crack defects presented at the CuSi3/304ss. Under the dual effects of reaction-promoted spreading at TC4 side and diffusion-promoted spreading at 304ss side, a wrap-around joint with high strength (∼407.6 MPa) was formed.

Purpose: To investigate the effect of chlorobenzoxime on respiratory syncytial virus (RSV) infection in vitro in lung alveolar cells and in vivo in neonatal rats, as well as the mechanism of action involved. Methods: RSV infection in neonatal rats was induced via intranasal administration of 2 x 106PFU viral particles. Reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting were used for determination of changes in interleukin expression. Results: RSV infection in BEAS-2B cells caused significant reduction in viability and marked alteration in morphological appearance (p < 0.05). Exposure of RSV-infected BEAS-2B cells to chlorobenzoxime prevented viability reduction and changes in morphology, and led to reductions in RSV-mediated increases in levels of interleukin-6 and interleukin-8. Moreover, RSV infection significantly enhanced ROS levels in BEAS-2B cells, when compared to control cells (p < 0.05). Chlorobenzoxime at a concentration of 30 μM completely suppressed RSV-mediated generation of ROS in BEAS-2B cells. In neonatal rats, RSV-induced upregulation of interleukin-4, interleukin-13 and TNF-α, were suppressed in bronchoalveolar lavage fluid (BALF) and lung tissues by chlorobenzoxime. Moreover, the RSVmediated reduction in IFN-γ was maximally blocked by chlorobenzoxime at a dose of 10 mg/mL. Chlorobenzoxime enhanced the proportion of IFN-γ -producing cells in neonatal rat BALF. Conclusion: Chlorobenzoxime exhibits antiviral against RSV infection in neonatal rats via increase in dendritic cell population, leading to inhibition of cytokine production. Therefore, chlorobenzoxime is a potential therapeutic agent for RSV infection. Keywords: Respiratory syncytial virus, Cytokines, Dendritic cells, Lung aveolar cells, Morphology, Interleukins

The effects of laser beam oscillation parameters on weld morphology, microstructure and mechanical properties of 304 stainless steel are investigated. The weld depth was increased at lower oscillation amplitudes with high frequency, while greatly decreased at higher oscillation amplitudes. The undercut defect was inhabited by beam oscillation. The periodical movement of laser beam caused a formation of vortex and some turbulence at the front of molten pool, which could increase the solidification rate and reduce the size of molten pool. Increasing beam oscillation frequency may disturb weld pool solidification more severely and cause more significant grain refinement. The growth direction of columnar crystal in the weld was changed. The content of ferrite was reduced and more skeletal ferrite was observed in the fusion zone in the case of beam oscillation. The microhardness and tensile strength value of beam oscillation welded joint was slightly increased than that of conventional welded joints. The ductile fracture mode with dimples was observed for all welded joints.

We report the first terminal trifluoromethylation at aryl and alkyl ketones' γ, δ, e, or more remote sites via the selective C-C bond cleavage of cycloalkanols. The noncovalent interactions between alcohols and hypervalent iodines(III) reagents were disclosed to activate both alcohols and the Togni I reagent in the dual photoredox/copper catalysis for the transformation. This reaction was scalable to the gram-scale synthesis, applicable to the structurally complex steroid trifluoromethylation, and extendable to the pentafluoroethylation.

The wetting behaviour of Al alloys (i.e., 6061 Al and 4043 Al alloys) on the surface of pure titanium was studied by sessile drop method at temperatures of 873–973 K under high vacuum with ˜10−4 Pa. All wetting processes were divided into two stages: in the nonlinear stage, the formation of a compact intermetallic layer (Ti7Al5Si12) blocked the mass transfer at solid/liquid (S/L) interface and deteriorated wetting, while the formation of loose phase (Al3Ti) at triple line region can removed the oxide film and improved wettability. The wetting activation energy (56 kJ/mol for a 6061Al/Ti system, and 71 kJ/mol for a 4043Al/Ti system) corresponded to the sum of the difference in surface energy per molar area between α-Ti and TiO2 (27.2 kJ/mol), and the Gibbs energy of formation for Al3Ti (30 kJ/mol) or the decomposition energy for Ti7Al5Si12 (48 kJ/mol). In the near-linear stage, the droplet spread on the surface of intermetallic compound (IMC). The spreading dynamics for 6061 alloy satisfied the Jiang’s empirical equation, and for 4043 alloy satisfied the viscous dissipation-limited model. The interfacial reaction had little effected on a droplet spreading, while the viscous friction drove the spread of 4043 alloy on precursor film in the near-linear stage. Keywords: Interfacial mass transfer, Reactive wettability, Activation energy, Al-Ti

Residual stress in metal cutting is critical due to its significant influence on the work performance of the workpiece. A 3D analytical model of residual stress appropriate for flank milling is established in this paper which takes both mechanical effect and thermal effect into consideration. Firstly, the 3D mechanical stress component is calculated considering its instantaneous and intermitted properties in the milling process. Elastic semi-infinite space contact mechanics and coordinate transformation are employed in the calculation process. Subsequently, the temperature distribution in the workpiece and corresponding thermal stress component are acquired based on the time-varying transient moving heat source model in the milling process. The plastic stress component is calculated based on the radial return method, in which all the stress components are updated during the plastic loading process. Finally, the measurement experiments for milling temperature and residual stress are performed to validate the theoretical models proposed in this work. The fine consistency between the prediction and the experiment demonstrates the accuracy of the prediction model. According to the calculation results of the proposed theoretical model, the plowing effect induced by the squeeze of the cutting edge on the work material is the major source of the residual stress.

The first visible-light-induced acyl radical Smiles rearrangement to transform biaryl ethers to hydroxybenzophenones under mild and metal-free conditions is reported. Using the dual catalysis of hypervalent iodine(III) reagents and organophotocatalysts, ketoacids readily generate acyl radicals and undergo 1,5- ipso addition. This method can construct electron-deficient and electron-rich hydroxybenzophenones with excellent chemoselectivity and on gram scale. The performance of the reaction in neutral aqueous conditions holds potential for future biomolecule applications.

The 6061 aluminum alloy and 304 stainless steel were welded by hybrid cold metal transfer (CMT) welding with external axial magnetic field. The effects of magnetic intensity and frequency on joint microstructure and mechanical properties were studied. It was found that the magnetic field can promote the spreading of aluminum weld metal on the steel surface and thus increase the bonding area of Al/steel butt joint. The welding process stability improved, while the wetting behavior worsened with the introduction of alternating frequencies. The thickness of the intermetallic compound (IMC) layer at Al/steel interface was reduced to 3 &mu, m with the coil current of 2 A. The application of the magnetic field promoted the aggregation of Si atoms at the interface and inhibited the formation of brittle (Al, Si)13Fe4 phase. The fracture paths were transformed from (Al, Si)13Fe4 layer to Al8Fe2Si layer with the application of the magnetic field. The maximum tensile strength reached 130.2 MPa, an increase of 61.6% in comparison to the normal CMT process.

Al6061-T6 and TC4 alloys were successfully joined via an external axial magnetic field hybrid cold metal transfer process. The visual sensing of arc behavior and droplet transfer process based on high-speed camera method has been adopted in an attempt to investigate the study of the welding process under magnetic field. The results showed that both the weld arc and the droplet transfer process were modified by the magnetic field. The charged particles exhibited a spiral motion and the weld arc changed to rotating bell shape. The droplet rotated around the wire and the spray transfer process was restrained with the application of magnetic field. Furthermore, the magnetic field could increase the spreading ability of molten pool. The temperature and holding time at the interface decreased, suppressing the growth behavior of brittle intermetallic compounds at the weld/Ti interface. The thickness of the intermetallic layer decreased from 9.7 μm in the normal welding process to 1.8 μm with a magnetic field. The maximum tensile shear load force of 4.21 kN was obtained and the fracture occurred at the heat affected zone of Al side.

Herein the first P-C(sp3 ) bond cleavage and radical alkynylation of α-phosphorus alcohols to construct phosphonoalkynes is reported. The phosphorus radical is generated upon P-C bond cleavage reaction via the alkoxyl radical through photoredox catalysis with cyclic iodine(III) reagents. Various arylphosphinoyl-, alkylphosphinoyl-, phosphonate-, and phosphonic amide alcohols serve as radical phosphorus precursors to construct phosphonoalkynes for the first time.

A novel, new approach of narrow gap laser wire feeding welding (NG-LWFW) with electromagnetic assisted wire wobbling is proposed to solve incomplete sidewall fusion and improve solidification morphology. The energy distribution and fusion zone formation during multi-pass NG-LWFW process are clarified. The melt pool is driven into sidewall position and the melted metal accumulates towards that side groove, leading to the increase of sidewall penetration with concave bead profile. The simulation results show that the wire wobbling obviously reduces peak temperature of melt pool and increases sidewall temperature. The heat affected zone (HAZ) width reduced, and a finer and diversity weld microstructure is presented. As multi-pass welding proceeds, the former weld is heat-treated by the latter weld, leading to the re-melting of columnar grains and increasing diversity of interlayer grains. The columnar crystal zone is refining and a narrower dendrite spacing of δ-ferrite phase is found with deposited filling layers. The micro-hardness of weld centerline shows an overall increase trend and the impact energy increases with denser dimples from the bottom layer to upper layer.

The wetting test is first used to study the effect of oscillating arc on the melt flow. A novel wetting method, single-sidewall wetting test, is developed to study the wetting behavior of melt on the narrow gap sidewall and its effect on lack-of-fusion defects is also discussed in arc oscillating NG-GTAW (narrow gap gas tungsten arc welding).The results show that the arc oscillation contributes to the improved wetting of melt on the plate and narrow gap sidewall. In the plate wetting test, variation of surface tension caused by heat input is crucial for wettability, while in the narrow gap, the improvement of wettability is attributed to the interaction of arc shear force, arc pressure and surface tension. As the increase of magnetic flux density, the wettability of melt on the sidewall in narrow gap gradually becomes better. However, the monotonic increasing trend of wettability with respect to the magnetic flux density does not always hold. When the best wettability is obtained, the melt surface is also more even, both of which can contribute to good fusion in the narrow gap. The welded joint without lack-of-fusion defect is obtained by using the magnetic field parameter covered with the best wettability of the melt on the sidewall.

An unexpected PtCl4-catalyzed cyclization reaction of tertiary indol-2-yl-3-alkynols occurred smoothly in toluene to form various poly-substituted carbazole derivatives efficiently. A possible mechanism involving the formation of a spiro-tricyclic intermediate via indole C-2 attack, highly selective ring expansion and then 1,2-migration has been proposed for the formation of carbazoles.

Ti-Fe intermetallic compounds were effectively suppressed with Cu-based filler wire and weld formation was greatly improved with the preheating of substrates when joining TC4 titanium alloy and 304 stainless steel. A Ti/Cu transition zone consisting of complex TiCu, Ti2Cu3, TiFe, and TiFe2 phases was formed between Cu-weld/TC4 interface, while Cu-weld/304ss interface was mainly composed of &alpha, Fe and &epsilon, Cu solid solution. At lower heat input, the undercut defect in back surface had potential to cause crack initiation and joint fracture. Though increasing heat input would improve weld morphology, the formation of thick interfacial reaction layer and weld cracking led to low weld quality and joint strength. The preheating of substrates had an obvious effect on wetting ability of liquid filler metal and could achieve a better weld quality at lower heat input. The back formation of weld was improved to decrease the occurrence of weld defects. The highest tensile strength of 365 MPa occurred at welding heat input of 0.483 kJ/cm, increasing by 47% compared to the joint without preheating. The interfacial reaction mechanism was discussed to reveal the relationship between microstructural characteristics and fracture behavior of Ti/steel welded joints with Cu-based filler wire.

Large and thick titanium alloy structures used in aerospace and marine fields need joint integrity to meet the requirements. Welding technology, an important form of joining materials, is crucial for the application and promotion of thick structural components. This paper reviews the issues and challenges in welding thick titanium alloys, introduces the process characteristics of automated welding technologies, and finally provides recommendations for future work. Research indicates that gas tungsten arc welding method with stable welding process is widely used in welding large titanium structures. As a promising alternative to traditional manufacturing method, laser welding with filler wire has been extensively studied in joining thick structure with the characteristics of narrower groove, high welding efficiency and low heat input. The formation mechanism and suppression measures of welding defects such as lack of sidewalls fusion, porosity, weld deformation and microstructural deterioration are discussed. The future work will focus on the welding process control and parameters optimization in automated welding.

Cutting vibration has a large influence on the machining accuracy and surface quality of thin-walled parts. An innovative and effective cutting vibration suppression method suitable for the milling of thin-walled cavity parts is proposed in this paper which is based on the shear thickening property of the corn starch suspension. Cutting vibration signals with and without the corn starch suspension are measured in milling experiments under different cutting parameters. Comparisons of the dynamic response of the workpiece in the time domain at different weight fractions of the corn starch suspension are carried out. A nonlinear dynamic model of the milling process with the corn starch suspension is established to analyse the effect of the corn starch suspension on the suppression of the cutting vibration. The influence of the corn starch on the cutting vibration suppression is analysed in the frequency domain. The theoretical analysis, coupled with the experimental results, demonstrates the excellent performance of the corn starch suspension in vibration suppression during the milling of a thin-walled cavity part. Both the chatter vibration and the forced vibration induced by the milling force are effectively suppressed by the corn starch suspension. The corn starch suspension has a pronounced impact hardening property and can be prepared rapidly. The cutting vibration suppression method proposed in this paper is convenient and environmentally friendly for application in the industrial production.

The influence of laser welding with beam oscillation on dynamic behavior of vapor plume, melt pool and keyhole was investigated. The stability of plume morphology is improved with a little fluctuation, and the height and area of plasma plume are decreased as the oscillation frequencies increased. The melt pool morphologies and flowing feature under beam oscillation conditions are also regulated due to the resultant energy deposition, which has an influence on weld solidification process. The re-melting effect of circular beam oscillation can eliminate pores formation and improve weld quality.

A novel, new approach of electromagnetic assisted wire wobbling to regulate energy allocation, melt flow and metallurgical structure is introduced in laser narrow gap welding of 316 L stainless steel. The formation of melt pool, weld surface morphologies and microstructure features in conventional laser welding, laser wobble welding and electromagnetic assisted wire wobble welding were compared. The results reveal that the forced convection generated by electromagnetic swing wire could broaden the melt pool size and compulsively push high-temperature weld metal towards groove sidewall. The wetting of liquid weld metal on groove sidewall was improved and concave weld morphology was obtained, thereby avoiding incomplete fusion of sidewall and favoring the filling of next weld bead. The temperature and element distribution in weld zone would be more uniform by the periodically and drastically forced convection, which helped to inhibit the growth of columnar crystals and promote the uniform distribution of elements. The average microhardness value in weld zone was uniform with the using of electromagnetic swing wire. Moreover, mechanisms of enhanced sidewall wetting and grain refinement were discussed in electromagnetic assisted wire wobble laser welding.

Laser welding of Ti6Al4V and 316L stainless steel is performed using single Cu interlayer and composite Cu-Nb interlayer. The microstructural characterization and mechanical properties of Ti6Al4V/316L steel laser welded joints at various laser offsets were investigated. Proper laser offset distance to 316L steel side ensured weld integrity and restrained mass production of intermetallic compounds for single Cu interlayer. Energy dispersive spectroscopy showed that Cu solid solution and discontinuous Ti-Fe and Ti-Cu intermetallics were formed due to the dissolution and diffusion of atoms. The joint had a lower tensile strength and fractured along Ti6Al4V/Cu weld interface with obvious cleavage steps and tongue pattern. The inserting of Nb interlayer with high-melting point was conducive to prevent atomic diffusion and suppress the formation of brittle intermetallics. Similarly, the laser energy distribution was crucial to the weld formation and metallurgical reaction in fusion zone. The Cu sheet and 316L steel was mainly connected by heat conduction. The weld fusion zone consisted of (Cu, Nb) and (Ti, Nb) solid solution with no intermetallics. Compared to the welded joints with single Cu interlayer, the microhardness of fusion zone was reduced and tensile strength was improved because no brittle IMCs were formed with composite Cu-Nb interlayer. The maximum tensile strength reached 215 MPa and ductile fracture mode occurred with composite Cu-Nb interlayer, which was approximately 160% greater than that found with single Cu interlayer.

To obtain excellent wettability under lower heat input, the role of external axial magnetic field was explored in wetting of liquid Cu on Ti and steel plate. The wetting activation energy decreased from 66 kJ/mol to 57.9 kJ/mol for the Cu/TC4 system, and from 78.9 kJ/mol to 51.8 kJ/mol for the Cu/304ss system when using a magnetic field, and the spreading limited factors changed from diffusion-limited to reaction-limited for the Cu/TC4 system. Besides this, the external axial magnetic field affected joint formation and interfacial microstructure: a wrap-around joint was formed on the Ti side and the spreading area of Cu on the steel plate surface was increased. A thick, continuous Ti2Cu3 and TiCu4 compound layer was transformed to a loose layer with multiple phases, consisting primarily of Cu, TiCu, Ti2Cu3, TiCu4, TiFe2, and Ti5Si3 therein. The Ti element segregated at the Cu/Fe interface and formed granular TiFe2 that was evenly distributed in the Fe–Cu solid solution, which transformed the original solid solution interface into a reaction interface. The highest tensile strength of 416 MPa increased by 44% compared to the joint without external magnetic field.

Incomplete fusion, pore and melt sagging are common defects for multi-layer narrow-gap laser welding with filler wire in vertical positions for large and heavy structures. This investigation showed that vertical-up laser welding had a lower sensitivity to pores than vertical-down welding, whereas increasing welding speed could improve welding stability and reduce the formation possibility of pores. For laser vertical welding with hot wire, surface tension transfer mode could effectively guarantee pre-heating of filler wire and achieve a stable welding process. The keyhole stability and melt flow varied with welding directions. The melt sagging defect was usually observed and mainly caused by the concentrated laser energy, which easily led to discontinuous weld bead. Laser beam oscillation technology increased laser melting area and promoted wetting behavior of filler wire with base metal. The weld width increased and concave weld metal surface was obtained with suitable process parameters. Narrow-gap welding process could be carried out at a small defocusing position with a lower laser power, further decreasing tendency of melt slagging. The 20-mm defect-free joint was obtained by vertical-up and vertical-down narrow-gap laser oscillation welding with hot wire.

Herein the first P-C(sp

An unexpected PtCl

Analysis of assembly tolerance is an important method to evaluate the reasonableness of tolerance allocation in product design. For the purpose of convenient applications, the method to assembly accuracy prediction presented in the paper is to extract the related assembly information from the CAD assembly model directly, which is managed in the way of data structures with inter-relationship and accessed with database technology. From the extracted assembly information, 3-D assembly dimension chains was automatically generated through searching the assembly constraints and their dependence and related dimension positions in the database. Then, the dimension chain is optimized by using ant colony algorithm to create an optimal one. Based on the input tolerance or actual dimension for each dimension/constraint, the assembly accuracy of the product can be predicted by the dimension chain and the accuracy prediction model. Taking a machine tool as an example, the accuracy prediction result shows that the predicted assembly accuracy meets the design specifications.

Residual stress in metal cutting is critical due to its direct influence on the performance of components. An analytical model of residual stress in orthogonal cutting is established in this paper. A constitutive stress updating algorithm based on the radial return (R-R) method is firstly employed in the plastic stress calculation of the residual stress analytical model. A thermal-mechanical model for the elastic stress in orthogonal cutting is established. Subsequently, the plastic stress is calculated based on the R-R method. The R-R method and corresponding stress release method are employed to model the residual stress on the machined surface. Orthogonal cutting experiments and residual stress measurements are conducted to verify the theoretical model proposed in this work. The consistency between the prediction values and the experiment results demonstrates the accuracy of the prediction model developed in this work. According to the theoretical model, the variations in the stress components, equivalent stress and yield stress during the stress updating process are analyzed. Comparisons for the discrepancy of the accuracy between the R-R method and the present plastic stress updating methods are carried out. The characteristics and advantages of the R-R method are discussed in detail to explain the reasons for the discrepancy in the accuracy compared with current methods. The results show that the analytical model proposed in this work can achieve a better prediction accuracy than the existing models, since the R-R method can avoid the problems of stress mutation and yield drift, and exhibits excellent flexibility and extensibility by reasonable assumptions and implicit calculation method.

The wetting behaviour of pure copper on the surface of TC4 titanium alloy and 304 stainless steel plates was studied by the sessile drop method at temperatures of 1273–1433 K under high vacuum. The FeO oxide film limited the solid/liquid interfacial mass transfer in a Cu/304ss system, but the TiO oxide film was not a limiting factor in a Cu/TC4 system. The potential spreading model was judged by the Rn-t relationship, in which n was close to 4 in a Cu/TC4 system, which confirmed the presence of diffusion-limited wetting. For Cu/304ss, 4 ≤ n ≤ 10: this indicated behaviour between that of the diffusion-limited reactive control model and the hydrodynamic model. At the Cu/304ss joining side, the wetting activation energy (55.1 kJ/mol) corresponded to the sum of the diffusion activation energy for Fe in liquid Cu (10 kJ/mol) and the difference in surface energy per molar area between Fe and FeO (44.9 kJ/mol). At the Cu/TC4 joining side, the wetting activation energy (23.6 kJ/mol) corresponded to the diffusion activation energy for Ti in liquid Cu (21 kJ/mol). The diffusion of Ti and Fe in molten Cu caused variations in capillary force, which were attributed to changes in the micro-grooves. Keywords: Wetting behaviour, Diffusion, Activation energy, Ti-Cu-steel

A simple and efficient method for the synthesis of 1,4-dihydroarenes by gold-catalyzed 6-endo cyclization of benzylic allenes has been developed. Furthermore, asymmetric hydroarylation of enantioenriched allenes has been realized to offer a practical and convergent approach to aromatic ring-fused six-membered cycles containing a chiral stereocenter such as 1,4-dihydronaphthalenes, 1,4-dihydrodibenzo[b,d]thiophenes, and 4,7-dihydrobenzo[b]thiophenes by applying dinuclear [(dppm)Au2 Cl2 ] [dppm=methylenebis(diphenylphosphane)] combined with AgOTf as the catalyst to ensure the high efficiency of chirality transfer. ESI-MS has been applied to characterize some of the key reactive dinuclear gold intermediates successfully.

The Guposhan-Huashan batholith was emplaced during transition from Tethysian tectonic regime to Pacific tectonic regime in the Middle-Late Jurassic. The regional EW-striking Yishan-Quannan basement deep fault zone, associated with the Tethysian regime, is thought likely to control the formation of the batholith. The development of the batholith was, however, achieved when the Pacific tectonic extensional regime dominated. The batholith consists of seven individual intrusive units that were emplaced subsequently over a 15 m.y. span. Deformation structures and strain analysis of the intrusive units and their country rocks suggest the existence of active and passive emplacement mechanisms. For example, shape-preferred orientation of dioritic enclaves and megacrystic K-spars within earlier units and the development of rim synforms resulted from active mechanisms. It is estimated that active expansion and structural propagation each contributed approximately 27%, and stoping accounted for 46% of the space for the entire batholith. The active emplacement mechanisms produced earlier units at deeper levels of the crust and followed by passive emplacement mechanism at shallower crustal levels when the tectonic regime changed from compression to extension. Each intrusive unit shows a different growth mode. Niumiao and Yangmeishan intrusions show a polarized lateral growth mode, the main-phase Lisong and Wanggao intrusions show either a central growth mode or an eccentric growth mode, and the youngest Baishuidai and Huamei units have a polarized multi-point central growth mode. Both Guposhan and Huashan plutons show a concentric growth zoning pattern with the former built in an outward growth style and the latter an inward growth style. The well-preserved circular shape of both plutons is indicative of relatively stationary magma feeders, suggesting that any considerable horizontal displacement in the region was unlikely even if the area was in an intracontinental strike-slip tectonic setting during the last emplacement phases of the batholith.

Virtual machining, based-on the model of a machining system, aims to simulate, evaluate and optimize the actual machining process with high sense of reality. It provides digital off-line optimization tools for NC machining. Taking advantage of virtual machining used in machining process simulation, one can build the framework of optimization system on NC machining so that the processes of reliability verification, cutting parameter optimization and error compensation can be integrated into one system to improve machining processes comprehensively. The optimization is realized via modifying NC programs. Several key issues such as virtual machining, cutting parameters optimization, error prediction and compensation are also highlighted. Optimization systems based on virtual machining have been developed to demonstrate the effectiveness of off-line optimization for different purposes. The results show that the machining process is obviously improved.

A simple and efficient method for the synthesis of 1,4-dihydroarenes by gold-catalyzed 6-endo cyclization of benzylic allenes has been developed. Furthermore, asymmetric hydroarylation of enantioenriched allenes has been realized to offer a practical and convergent approach to aromatic ring-fused six-membered cycles containing a chiral stereocenter such as 1,4-dihydronaphthalenes, 1,4-dihydrodibenzo[b,d]thiophenes, and 4,7-dihydrobenzo[b]thiophenes by applying dinuclear [(dppm)Au2 Cl2 ] [dppm=methylenebis(diphenylphosphane)] combined with AgOTf as the catalyst to ensure the high efficiency of chirality transfer. ESI-MS has been applied to characterize some of the key reactive dinuclear gold intermediates successfully.

Assembly planning for complex products is a difficult task requiring both intensive knowledge and experience. Computer aided assembly planning (CAAP) systems have been the subject of considerable research in recent years without achieving a wide application in manufacturing industry. In this paper an alternative approach to the generation of an optimal assembly planning scheme is presented based on the adoption of immersive virtual reality. A product is assembled from CAD models by providing a CAD interface to transfer assembly constraint information from the CAD system to a virtual environment. In the virtual environment an efficient dynamic recognition and management method based on surface geometry is employed, and a process-oriented assembly task model is established to support interactive assembly planning and evaluation. The system is implemented using an object oriented methodology, and has been successfully applied to train and guide the assembly workers in a pump assembly process.