Theoretical Investigations of the Activation of CO2 on the Transition Metal-doped Cu(100) and Cu(111) Surfaces

Periodic density functional theory calculations have been performed to investigate the chemisorption behavior of COz molecule on a series of surface alloys that are built by dispersing individual middle-late transition metal （TM） atoms （TM = Fe, Co, Ni, Ru, Rh, Pd, Ag, Os, lr, Pt, Au） on the Cu（100） and Cu（lll） surfaces. The most stable configurations of CO2 chemisorbed on different TM/Cu surfaces are determined, and the results show that among the late transition metals, Co, Ru, and Os are potentially good dopants to enhance the chemisorption and activation of CO2 on copper surfaces. To obtain a deep understanding of the adsorption property, the bonding characteristics of the adsorption bonds are carefully examined by the crystal orbital Hamilton population technique, which reveals that the TM atom primarily provides d orbitals with z-component, namely dz2, dxz, and dvz orbitals to interact with the adsorbate.

Surface and transport properties of Cu-Sn-Ti liquid alloys

The lack of experimental data and / or limited experimental information concerning both surface and transport properties of liquid alloys often require the prediction of these quantities. An attempt has been made to link the thermophysical properties of a ternary Cu-Sn-Ti system and its binary Cu-Sn, Cu-Ti and SnoTi subsystems with the bulk through the study of the concentration dependence of various thermodynamic, structural, surface and dynamic properties in the frame of the statistical mechanical theory in conjunction with the quasi-lattice theory （QLT）. This formalism provides valuable qualitative insight into mixing processes that occur in molten alloys.

The hysteresis loops of a ferroelectric bilayer film with surface transition layers

Based on the transverse Ising model in the framework of the mean field approximation, this paper discusses a ferroelectric bilayer film with the surface transition layers within each constituent slab and an antiferroelectric interracial coupling between two slabs. The hysteresis loop of a bilayer film is investigated. The results show that the surface transition layer in a ferroelectric bilayer film plays a significant role in realizing the multiple-state memory.

The First-principle Investigations on the Activation for CO2 on TM(TM = Fe,Co,Ni,Cu) Supported Cu Surface

Periodic density functional theory calculations have been carried out to investigate the effect of TM atom supported on different Cu surfaces towards the activation for CO2 molecules. The most stable configuration of CO2 on various TM/Cu（TM = Fe, Co, Ni, Cu） surfaces is determined and the results show that the cobalt is potentially excellent admetal to enhance the chemisorption of CO2 on copper surfaces among the late 3 d-metals. To deep understand the adsorption property, the bond characteristics of the adsorption bonds are carefully examined by the crystal orbital Hamilton population technique and charge density difference analysis. The result reveals that the interaction between the CO2 molecule and TM/Cu surface primarily derive from the TM–C bond. Moreover, the defined adsorption bond strength（I） between CO2 and substrate could be a descriptor for TM-supported surface.

Density Functional Theory Study on the Adsorption of CN on Transition Metal M(100) (M = Ni, Pd, Pt, Cu, Ag and Au) Surfaces

The adsorption of cyanide on the top site of a series of transition metal M（100） （M = Cu, Ag, Au, Ni, Pd, Pt） surfaces via carbon and nitrogen atoms respectively, with the CN axis perpendicular to the surface, has been studied by means of density functional theory and cluster model. Geometry, adsorption energy and vibrational frequencies have been determined, and the present calculations show that the adsorption of CN through C-end on metal surface is more favorable than that via N-end for the same surface. The vibrational frequencies of CN for C-down configuration on surface are blue-shifted with respect to the free CN, which is contrary to the change of vibrational frequencies when CN is adsorbed by N-down structure. Furthermore, the charge transfer from surface to CN causes the increase of surface work function.

METABALL-BASED TRANSITION SURFACES

Metaball-based constraint deformation technique is used to change the definition of r, the straight-line distance from a space point to a constraint center in the original calculation of the potential function. By replacing the parameter of the pararnetrized surface w with the straight-line distance r, a method of building transition surfaces according to cormected boundary curves and skeleton curves is proposed. The method has no restrictions on boundary curves that control the space shapes of transition surfaces or on types of skeleton curves, thus transition surfaces, which reach C^1 continuity and are more abundant in shapes and natural, can be obtained.

An Application Study of Transition Surface Reconstruction in Reverse Engineering

the reconstruction of transition surface is one of time consuming activities during surface modeling in reverse engineering. Yet currently available software applications suffer from shortcoming in processing the connection among free form surfaces. In this paper, a new method is put forward combining Surfacer with Unigraphics to resolve this problem: Curves and surfaces are first constructed in Surfacer, then, the finished data is imported into Unigraphics based on IGES fonnat. At last, the transition surface can be reconstructed in Unigraphics. The application of this method in transition surface reconstruction is illustrated by means of two case studies, showing the connection between free form surfaces; filleting and rounding among multiple surfaces: transition surface between two sets of surfaces.

Millipede forming-a new metal forming approach

Millipede Forming is a novel metal forming method that has been proposed and developed recently.It can be applied to overcome fundamental limitations in conventional roll forming,and,in addition,used for incremental forging and integrated into a strip casting or extrusion process for downstream thickness reduction. In this new method,there are two main principles:①the use of an optimal transitional surface or space linking of the incoming material to the outgoing product,and②implementation of a method to feed the material through the forming device so that it conforms with this ideal space and the required deformation is imposed on it by the tooling. The system described here is called "Millipede forming" because deformation is accomplished in a large number of small steps.A prototype has been built to demonstrate the working principle applied to the replacement of a roll forming process;it can be used to produce simple profiles within a forming length an order of magnitude shorter than the conventional process. In this paper,the working principle of "Millipede forming" is introduced and some fundamental research on forming a channel section and a circular tube is discussed.Following the success of the small scale prototype, research on a full scale pilot machine has been proceeding.It is expected that this process can be developed and extended as a useful alternative to conventional roll forming,incremental forging and within a strip casting or other novel strip material(e.g.nanostructured metals) system.

Ethylene Adsorption on Ag(111), Rh(111) and Ir(111) by(meta)-GGA based Density Functional Theory Calculations

Accurate description of the adsorption process of reactants on metal surfaces from theory is crucial for mechanistic understanding of activity and selectivity of metal catalysts, but it remains challengeable for the nowadays first-principles theory due to the lack of proper exchange-correlation functional describing the distinct interactions involved. We studied here the potential energy surfaces of ethylene adsorption on Ag(111), Rh(111) and Ir(111) using density functional theory calculations and (meta)-GGA functional including PBE, BEEF-vdW, SCAN, and SCAN+rVV10. For ethylene adsorption on noble metal Ag(111), it is found that BEEF-vdW, SCAN and SCAN+rVV10 predict the presence of the physisorption states only. For Rh(111), both SCAN and SCAN+rVV10 find that there is a precursor physisorption state before the chemisorption state. In contrast, there is no precursor state found based on potential energy surfaces from BEEF-vdW and PBE. Whereas for Ir(111), BEEF-vdW predicts the existence of a rather shallow precursor physisorption state, in addition to the chemisorption state. Irrespective to the transition metals considered, we find that SCAN+rVV10 gives the strongest binding strength, followed by SCAN, and PBE/BEEF-vdW, accordingly. The present work highlights great dependence of potential energy surface of ethylene adsorption on transition metal surfaces and exchange-correlation functionals.

POLYMER CHAIN DIFFUSION AT A TEMPERATURE BELOW ITS BULK GLASS TRANSITION TEMPERATURE

In this study, it was examined whether the dynamics of polymer chains at a surface is different from that in thebulk, and if so, to what extent they differ in terms of surface glass transition temperature and diffusion coefficient. Obtainedresults clearly indicate that surface chains can travel for a relatively large distance in comparison with the characteristiclength scale of usual segmental motion even at a temperature below its bulk glass transition temperature, T_g^b. This isconsistent with our previous results that the surface glass transition temperature is much lower than the corresponding T_g^b.Also, it was experimentally revealed that there was a gradient of molecular motion in the surface region.

Observation of lateral long range order in superconducting FeTe thin films

We find that the superconductivity in the thin films of the formerly believed non-superconducting parent compound FeTe is accompanied by an emergence of second order with a correlation length of 742 nm and 258 nm at 10 K and 300 K, respectively. The structural phase transition found in iron pnictide superconductors, in non-superconducting FeTe bulk samples, and in FeSe superconducting thin films is not observed in the superconducting FeTe thin films. The interplay between superconductivity and long range order may suggest the crucial role of competition between electronic localization and itinerancy which leads to strong quantum fluctuations in the FeTe system.

Phase Diagrams of the Semi-Infinite Blume-Capel Model with Mixed Spins (SA = 1 and SB = 3/2) by Migdal Kadanoff Renormalization Group

We study the mixed spin-1 and spin-3/2 Blume-Capel model under crystal field in the tridimensional semi-infinite case. This has been done by using the real-space renormalization group approximation and specifically the Migdal-Kadanoff technique. As a function of the ratio R of bulk and surface interactions and the ratios R1 and R2 of bulk and surface crystals fields on the spin-1 and spin-3/2 respectively, we have determined various types of phase diagrams. Besides second- order transition lines, first-order phase transition lines terminating at tricritical points are obtained. We found that there existed nine main types of phase diagram showing a variety of phase transitions associated with the surface, including ordinary, extraordinary, surface and special phase transitions.

The effect of G?rtler instability on hypersonic boundary layer transition

The evolution of Gortler vortices and its interaction with other instabilities are investigated in this paper. Both the Mack mode and the Gortler mode exist in hypersonic boundary-layer flows over concave surfaces, and their interactions are crucially important in boundary layer transition. We carry out a direct numerical simulation to explore the interaction between the GOrtler and the oblique Mack mode. The results indicate that the interaction between the forced Gortler mode and the oblique Mack mode promotes the onset of the transition. The forced oblique Mack mode is susceptible to nonlinear interaction. Because of the development of the GOrtler mode, the forced Mack mode and other harmonic modes are excited.

Mysterious Waters at Metal Surfaces

Molecular structures of adsorbed waters at metal surfaces are essential to understanding the widespread processes ranging from ice nucleation,to water involved catalytic surface reactions,to many phenomena of biological and astrochemical importance.Instead of providing a comprehensive literature survey,we focus in this review on detailed structural information,such as water orientations and occupation sites,of intact waters at low temperatures and ultrahigh vacuum conditions investigated by various surface techniques.Despite progresses made in direct imaging the surface waters at high resolutions,as exemplified in a close-packed（e.g.Pd（111）） and an open metal surfaces（e.g.Cu（110）） supported waters,structural mysteries remain at diverse metal surfaces.We highlight experimental challenges and discuss structural mysteries in elucidating surface water structures at molecular levels.

Optimization approach for a climbing robot with target tracking in WSNs

Climbing robots are being developed for various applications.The confined space requires a compact locomotion system with vertical and overhead climbing ability.To achieve surface transition,Steering geometry Interaction system and static force are used.WSNs ubiquitous infrastructure and excellent coverage,they can be used for providing location information for various location-based services,especially in indoor environments.This structure is designed for a magnetic wall-climbing robot to gradually decrease the magnetic force when it is transiting between perpendicular magnetic surfaces.This paper describes the design process of a magnetic wall climbing robot,which adopts SgI and has the potential to carry materials in a confined space with an energy efficient system model.To resolve the problem of target tracking,it is essential to deploy a system model.Over the last two decades,several researchers have recommended many remote user authentication schemes.Researchers are continuously trying to enhance the security in material handling automation system by introducing several features into their work.A working prototype has been built based on the optimized dimension.

Analysis of the electrical characteristics of GaInP/GaAs HBTs including the recombination effect

An analytical model is used to predict the effects of surface recombination current on the gain and transit time of GalnP/GaAs heterojunction bipolar transistors（HBTs）.The present analysis shows that consideration of the recombination current gives current gain values that are comparable to those of the experimental results.The dependence of current gain on temperature,base doping and emitter area are also analyzed,and the variation in collector current with emitter-base voltage,temperature and doping is considered.

Poly(N-isopropylacrylamide)-grafted Dual Stimuli-responsive Filter Paper for Protein Separation

Thermal and salt dual stimuli-responsive filter-paper-based membranes were prepared by UV-induced grafting of NIPAM-based polymers on paper surface. The grafting ratio could be controlled by monomer concentration during grafting polymerization. The results from pressure drop measurement of the mobile phase flowed cross the membrane demonstrate that an appropriate grafting ratio would be 8%-10%. Protein adsorption on the membrane through hydrophobic interaction could be promoted by increasing temperature and lyotropic salt concentration. The effect of grafted polymer structure on protein binding performance was studied. Filter paper grafted with NIPAM-based branched copolymer consisting of hydrophobic monomer moieties shows ten times higher protein binding capacity than that of the original filter paper. The separation of plasma proteins using the dual stimuli-responsive membrane was examined to demonstrate feasible application for hydrophobic interaction chromatographic separation of proteins.

Spin-flop transition and Zeeman effect of defect-localized bound states in the antiferromagnetic topological insulator MnBi_(2)Te_(4)

The correlation of surface impurity states with the antiferromagnetic ground states is crucial for understanding the formation of the topological surface state in the antiferromagnetic topological insulators MnBi_(2)Te_(4).By using low-temperature scanning tunneling microscopy and spectroscopy,we observed a localized bound state around the Mn-Bi antisite defect at the Teterminated surface of the antiferromagnetic topological insulator MnBi_(2)Te_(4).When applying a magnetic field perpendicular to the surface(Bz)from–1.5 to 3.0 T,the bound state shifts linearly to a lower energy with increasing Bz,which is attributed to the Zeeman effect.Remarkably,when applying a large range of Bz from–8.0 to 8.0 T,the magnetic field induced reorientation of surface magnetic moments results in an abrupt jump in the local density of states(LDOS),which is characterized by LDOSchange-ratio■quantitatively.Interestingly,two asymmetric critical field,–2.0 and 4.0 T determined by the two peaks in■are observed,which is consistent with simulated results according to a Mills-model,describing a surface spin flop transition(SSF).Our results provide a new flatform for studying the interplay between magnetic order and topological phases in magnetic topological materials.