Experimental study of the mass transfer behavior of carbon dioxide absorption into ternary phase change solution in a packed tower

Phase change absorbents for CO_(2)are of great interest because they are expected to greatly reduce the heat energy consumption during the regeneration process.Compared with other phase change absorbents,monoethanolamine(MEA)-sulfolane-water is inexpensive and has a fast absorption rate.It is one of the most promising solvents for large-scale industrial applications.Therefore,this study investigates the mass transfer performance of this phase change system in the process of CO_(2)absorption in a packed tower.By comparing the phase change absorbent and the ordinary absorbent,it is concluded that the use of MEA/sulfolane phase change absorbent has significantly improved mass transfer efficiency compared to a single MEA absorbent at the same concentration.In the 4 mol·L^(-1)MEA/5 mol·L^(-1)sulfolane system,the CO_(2)loading of the upper liquid phase after phase separation is almost zero,while the volume of the lower liquid phase sent to the desorption operation is about half of the total volume of the absorbent,which greatly reduces the energy consumption.This study also investigates the influence of operating parameters such as lean CO_(2)loading,gas and liquid flow rates,CO_(2)partial pressure,and temperature on the volumetric mass transfer coefficient(K_(G)α_(V)).The research shows that K_(G)α_(V) increases with increasing liquid flow rate and decreases with the increase of lean CO_(2)loading and CO_(2)partial pressure,while the inert gas flow rate and temperature have little effect on K_(G)α_(V).In addition,based on the principle of phase change absorption,a predictive equation for the K_(G)α_(V) of MEA-sulfolane in the packed tower was established.The K_(G)α_(V) obtained from the experiment is consistent with the model prediction,and the absolute average deviation(AAD)is 7.8%.

Fabrication of Cu_2O@Cu_2O core-shell nanoparticles and conversion to Cu_2O@Cu core-shell nanoparticles in solution

Cu2O@Cu2O core-shell nanoparticles (NPs) were prepared by using solution phase strategy. It was found that Cu2O@Cu2O NPs were easily converted to Cu2O@Cu NPs with the help of polyvinylpyrrolidine (PVP) and excessive ascorbic acid (AA) in air at room temperature, which was an interesting phenomenon. The features of the two kinds of NPs were characterized by XRD, TEM and extinction spectra. Cu2O@Cu NPs with different shell thicknesses showed wide tunable optical properties for the localized surface plasmon (LSP) in metallic Cu. But Cu2O@Cu2O NPs did not indicate this feature. FTIR results reveal that Cu+ ions on the surface of Cu2O shell coordinate with N and O atoms in PVP and are further reduced to metallic Cu by excessive AA and then form a nucleation site on the surface of Cu2O nanocrystalline. PVP binds onto different sites to proceed with the reduction utill all the Cu sources in Cu2O shell are completely assumed.

Morphology-Controlled Synthesis of ZnxCd1-xS Solid Solutions: An Efficient Solar Light Active Photocatalyst for the Degradation of 2,4,6-Trichlorophenol

ZnxCd1-xS solid solutions with controlled morphology have been successfully synthe-sized by a facile solution-phase method. The prepared samples were characterized by X-ray powder diffraction (XRD), UV-vis diffuse reflectance spectra, X-ray photoelec-tron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission elec-tron microscopy (TEM). The photocatalytic activity of ZnxCd1-xS was evaluated in the 2,4,6-trichlorophenol (TCP) degradation and mineralization in aqueous solution under direct solar light illumination. The experiment demonstrated that TCP was effectively degraded by more than 95% with 120 min. The results show that ZnS with Cd doping (ZnxCd1-xS) exhibits the much stronger visible light adsorption than that of pure ZnS, the light adsorption increasing as the Cd2+ doping amount. These results indicate that Cd doping into a ZnS crystal lattice can result in the shift of the valence band of ZnS to a positive direction. It may lead to its higher oxidative ability than pure ZnS, which is important for organic pollutant degradation under solar light irradiation. Further-more, the photocatalytic activity studies reveal that the prepared ZnxCd1-xS nanostructures exhibit an excellent photocatalytic performance, degrading rapidly the aqueous 2,4,6-trichlorophenol solution under solar light irradiation. These results sug-gest that ZnxCd1-xS nanostructure will be a promising candidate of photocatalyst working in solar light range.

The Interaction and Degeneracy of Mixed Solutions for Derivative Nonlinear Schrodinger Equation

The mixed solutions of the derivative nonlinear Schrödinger equation from the trivial seed (zero solution) are derived by using the determinant representation. By adjusting the interaction and degeneracy of mixed solutions, it is possible to obtain different types of solutions: phase solutions, breather solutions, phase-breather solutions and rogue waves.

Peregrine Rogue Waves Generated by the Interaction and Degeneration of Soliton-Like Solutions: Derivative Nonlinear Schrödinger Equation

We study the Peregrine rogue waves within the framework of Derivative Nonlinear Schrödinger equation, which is used to describe the propagation of Alfven waves in plasma physics and sub-picosecond or femtosecond pulses in nonlinear optics. The interaction and degeneration of two soliton-like solutions and its relations for the breather solution have been analyzed. The Peregrine rogue waves have been considered from the two kinds of formation processes: it can be generated through the limitation of the infinitely large period of the breather solutions, and it can be interpreted as the soliton-like solutions with different polarities. As a special example, a special Peregrine rogue wave is generated by a breather solution and phase solution, which is given by the trivial seed (zero solution).

Direct spray pyrolysis of aluminum chloride solution for alumina preparation

The effects of pyrolysis mode and pyrolysis parameters on Cl content in alumina were investigated, and the alumina products were characterized by XRD, SEM and ASAP. The experimental results indicate that the spray pyrolysis efficiency is higher than that of static pyrolysis process, and the reaction and evaporation process lead to a multi-plot state of the alumina products by spray pyrolysis. Aluminum phase starts to transform into γ-Al2O3 at spray pyrolysis temperature of 600 °C, which is about 200 °C lower than that of static pyrolysis process. The primary particle size of γ-Al2O3 product is 27.62 nm, and Cl content in alumina products is 0.38% at 800 °C for 20 min.

Total Synthesis of N-Methylsansalvamide A

Total synthesis of N-methylsansalvamide A was accomplished in solution phase by a convergent approach. An N-Boc-td-depsipepide 6 and a dipeptide ester 10 were prepared in the yield of 89% and 91%, respectively. Cyclization of the linear penta-depsipetide was achieved with PyBOP and DIPEA in DMF-CH2C12.

A New Solution-phase Parallel Synthesis of 2-Alkylamino-3-aryl-5-phenylmethylene-3,5-dihydro-4H-imidazol-4-ones

Thirteen new 2 alkylaminoimidazolones (4) were rapidly synthesized by a new solution phase parallel synthetic method, which includes aza Wittig reaction of iminophosphorane (1) with aromatic isocyanate to give carbodi imide (2) and subsequent reaction of 2 with various aliphatic primary amine in a parallel fashion. The products were confirmed by 1H NMR, MS, IR and X ray crystallographic analysis. The unusual selectivity of the cyclization was probably due to the geometry of the guanidine intermediate.

Mechanical behaviors of NiAl-Cr(Mo)-based near eutectic alloy with Ti, Hf, Nb and W additions

Effects of Ti, Hf, Nb and W alloying elements addition on the microstructure and the mechanical behaviors of NiAl-Cr（Mo） intermetallic alloy were investigated by means of XRD, SEM, EDX and compression tests. The results show that Ni-31Al-30Cr-4Mo-2（Ti, Hf, Nb, W） alloy consists of four phases： NiAl, ？？Cr solid solution, Cr2Nb and Ni2Al（Ti, Hf）. The mechanical properties are improved significantly compared with the base alloy. The compression yield strength at 1 373 K is 467 MPa and the room temperature compression ductility is 17.87% under the strain rate of 5.56？？0-3 s-1, due to the existence of Cr2Nb and Ni2Al（Ti, Hf） phases for strengthening and Ti solid solution in NiAl matrix and coarse Cr（Mo, W） solid solution phase at cellular boundaries for ductility. The elevated temperature compression deformation behavior of the alloy can be properly described by power-law equation： ε=0.898 σ8.47exp[-615/（RT）].

EXISTENCE UNIQUENESS AND ASYMPTOTIC STABILITY OF PERIODIC SOLUTIONS OF A NONLINEAR EQUATION IN PHASE LOCKED TECHNOLOGY

In [1] and [2], the authors made a deep qualitative analysis of the equationwith the character of tangent detected phase and they mathematically provided atheoretical basis of why the phase looked loop has no look--losing point. However,according to many practical experts, it is rather difficult to put such a phaselooked loop into practice, though it has fine properties. W. C. Lindsey [3] made a

Three-dimensional Numerical Simulation of Viscoelastic Phase Separation under Shear: the Roles of Bulk and Shear Relaxation Moduli

The morphological, dynamic and rheological characteristics in the viscoelastic phase separation（VPS） of sheared polymer solutions are investigated by three-dimensional（3D） numerical simulations of viscoelastic model. The simulations are accelerated by graphic process unit（GPU） to break through the limitation of computation power. Firstly, the morphological and dynamic characteristics of VPS under shear are presented by comparing with those in classic phase separation（CPS）. The results show that the phase inversion and phase shrink take place in VPS under shear. Then, the roles of bulk and shear relaxation moduli in VPS are investigated in details. The bulk relaxation modulus slows down the phase separation process under shear, but not affects the dynamic path of VPS. The dynamic path can be divided into three stages： freezing stage, growth stage and stable stage. The second overshoot phenomenon in the shear stress is observed, and explained by the breakdown and reform of string structures. The shear modulus affects morphology evolution in the late stage of VPS under shear.

Drag Effects of Solute and Second Phase Distributions on the Grain Growth Kinetics of Pre-Extruded Mg-6Zn Alloy

In order to control the grain size during hot forming,grain growth behavior of a pre-extruded Mg-6Zn magnesium alloy and its correlation with solute and second phase distribution were investigated.Isothermal annealing was conducted on a Gleeble-1500 thermo-mechanical simulator.The mean grain size Dg of each annealed specimen was measured by the quantitative metallography technique.The grain growth kinetics of the Mg-6Zn alloy annealed at 473-623 K was obtained as Dg^4- Dg0^4=2.25 ×10^11 exp（-95450）by the least square linear regression method.The deviation of grain growth exponent n = 4 from the theoretical value of 2 may be attributed to the presence of solute zinc and second phases which will retard the boundary migration.Microscopic observations show that the non-uniform distribution of grain size for samples pre-extruded or annealed at low temperatures is closely related to the non-uniform distribution of fine and dispersed second phases but not to the non-uniform distribution of solute zinc.This indicates that second phase pinning effect plays an important role in microstructure refinement.

Thermodynamic Characteristic and Phase Evolution in Immiscible Cr–Mo Binary Alloys

This paper systematically reports the thermodynamic characteristic and phase evolution of immiscible Cr–Mo binary alloy during mechanical alloying（MA） process. The Cr–35Mo（in at%） powder mixture was milled at 243 and258 K, respectively, for different time. For comparative study, Cr–15Mo and Cr–62Mo powder mixtures were milled at 243 K for 18 h. Solid solution Cr（Mo） with body-centered cubic（bcc） crystal structure and amorphous Cr（Mo） alloy was obtained during MA process caused by high-energy ball milling. Based on the Miedema＇s model, the free-energy change for forming either a solid solution or an amorphous in Cr–Mo alloy system is positive but small at a temperature range between 200 and 300 K. The thermodynamical barrier for forming alloy in Cr–Mo system can be overcome when MA occurs at 243 K, and the supersaturated solid solution crystal nuclei with bcc structure form continually, and three supersaturated solid solutions of Cr–62Mo, Cr–35Mo and Cr–15Mo formed. Milling the Cr–35Mo powder mixture at 258 K, the solid solution Cr（Mo） forms firstly, and then the solid solution Cr（Mo） transforms into the amorphous Cr（Mo）alloy with a few of nanocrystallines when milling is prolonged. At higher milling temperature, it is favorable for the formation of the amorphous phase, as indicated by the thermodynamical calculation for immiscible Cr–Mo alloy system.

Steady-state solution growth of microcrystalline silicon on nanocrystalline seed layers on glass

The growth of polycrystalline silicon layers on glass from tin solutions at low temperatures is presented.This approach is based on the steady-state solution growth of Si crystallites on nanocrystalline seed layers, which are prepared in a preceding process step. Scanning electron microscopy and atomic force microscopy investigations reveal details about the seed layer surfaces, which consist of small hillocks, as well as about Sn inclusions and gaps along the glass substrate after solution growth. The successful growth of continuous microcrystalline Si layers with grain sizes up to several ten micrometers shows the feasibility of the process and makes it interesting for photovoltaics.

Synthesis of Monodisperse CdS Nanorods Catalyzed by Au Nanoparticles

Semiconductor nanocrystals(dots,rods,wires,etc.)exhibit a wide range of electrical and optical properties that differ from those of the corresponding bulk materials.These properties depend on both nanocrystal size and shape.Compared with nanodots,nanorods have an additional degree of freedom,the length or aspect ratio,and reduced symmetry,which leads to anisotropic properties.In this paper,we report the Au nanoparticle-catalyzed colloidal synthesis of monodisperse CdS nanorods.Based on systematic high resolution transmission electron microscopy studies,we propose a growth mechanism for these nanorods.

Synthesis and Pharmacological Studies on a Cyclooligopeptide from Marine Bacteria

A natural proline-rich tetrapeptide cyclo-prolyl-leucyl-prolyl-phenylalanyl was prepared employing solu- tion-phase method of peptide synthesis through coupling of dipeptide fragments Boc-l-Pro-l-Leu-OH and 1-Pro-l-Phe-OMe which utilizes diisopropylcarbodiimide （DIPC） as coupling agent and N-methylmorpholine （NMM） as the base. Deprotection of linear tetrapeptide unit followed by its cyclization provided a cyclopeptide, identical in all aspects to the natural molecule. Pharmacological evaluation showed cytotoxic, antifungal and antihelmintic po- tential of synthesized peptide against Dalton＇s Lymphoma Ascites （DLA） and Ehrlich＇s Ascites Carcinoma （EAC） cell lines, pathogenic dermatophytes and earthworms.