Mechanism study on the influence of surface properties on the synthesis of dimethyl carbonate from CO_(2)and methanol over ceria catalysts

The direct synthesis of dimethyl carbonate(DMC)from CO_(2)and methanol has attracted much attention as an environmentally benign and alternative route for conventional routes.Herein,a series of cerium oxide catalysts with various textural features and surface properties were prepared by the one-pot synthesis method for the direct DMC synthesis from CO_(2)and methanol,and the structure-performance relationship was investigated in detail.Characterization results revealed that both of surface acid-base properties and the oxygen vacancies contents decreased with the rising crystallinity at increasingly higher calcination temperature accompanied by an unexpectedly volcano-shaped trend of DMC yield observed on the catalysts.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)studies indicated that the adsorption rate of methanol is slower than that of CO_(2)and the methanol activation state largely influences the formation of key intermediate.Although the enhanced surface acidity-basicity and oxygen vacancies brought by low-temperature calcination could facilitate the activation of CO_(2),the presence of excess strongly basic sites on low-crystallinity sample was detrimental to DMC synthesis due to the preferred formation of unreactive mono/polydentate carbonates as well as the further impediment of methanol activation.Moreover,with the use of 2-cyanopyridine as a dehydration reagent,the DMC synthesis was found to be both influenced by the promotion from the rapid in situ removal of water and the inhibition from the competitive adsorption of hydration products on the same active sites.

Preparation and Surface Properties of Silicon-Containing Waterborne Polyurethane Functionalized with Fluorine-Containing Acrylate and Micro-Nano Silica

In order to prepare hydrophobic waterborne polyurethane coatings with better performances, the silicon-containing waterborne polyurethane（SiWPU） with functional chain extender hydroxyethyl acrylate（HEA） was prepared first, and then a series of silicon＆fluorine-containing polyurethane/acrylate（FSiPUA） emulsions were obtained with flourine containing acrylic monomer by seed emulsion polymerization, introducing micro-nano SiO2 into FSiPUA emulsion to make the final hybrid emulsion. The properties of Si WPU, FSiPUA and SiO2/FSiPUA were investigated by fourier transform infrared spectra（FTIR）, transmission electron microscope（TEM）, Scanning Electron Microscope（SEM） and some other analytical methods. The results revealed that FSiPUA emulsion particles possessed composite core-shell structure and FSiPUA films with suitable ratio performed better than Si WPU films in hardness, water resistance and solvent resistance. The SiO2/FSiPUA films with micro-nano dual roughness structure showed a water contact angle of 136° with good resistance to acid and alkali.

The Impact of Surface Properties on Downward Surface Shortwave Radiation over the Tibetan Plateau

The complexity of inhomogeneous surface-atmosphere radiation transfer is one of the foremost problems in the field of atmospheric physics and atmospheric radiation. To date, the influence of surface properties on shortwave radiation has not been well studied. The daily downward surface shortwave radiation of the latest FLASHFlux/CERES （Fast Longwave And Shortwave Fluxes_Time Interpolated and Spatially Averaged/Clouds and the Earth＇s Radiant Energy System） satellite data was evaluated against in situ data. The comparison indicated that the differences between the two data sets are unstable and large over rugged terrain compared with relatively flat terrain, and the mean absolute error of the satellite products reaches 31.4 W m-2 （12.3%） over rugged terrain. Based on the SSF （single satellite footprint）/CERES product, the influence of surface properties on the distribution of downward surface shortwave radiation （DSSR） was analyzed. The influence of surface properties on DSSR over the Tibetan Plateau is about twice as large as that in two other regions located at the same latitude （eastern China-western Pacific and subtropical North Pacific）. A simulation was carried out with the help of the I3RC （International Intercomparision of Three-Dimensional Radiation Code） Monte Carlo 3D radiative transfer community model. The results showed that DSSR increases as surface albedo increases. Moreover, the impact of surface albedo on DSSR is larger if the spatial distribution of clouds is more non-uniform. It is hoped that these results will contribute to the development of 3D radiative transfer models and the improvement of satellite inversion algorithms.

COMPARISON OF SURFACE PROPERTIES OF Ti-6Al-4V COATED WITH TITANIUM NITRIDE, TiN+TiC+Ti(C,N)/DLC, TiN/DLC AND TiC/DLC FILMS BY PLASMA-BASED ION IMPLANTATION

The surface properties of Ti-6Al-4V alloy coated with titanium nitride, TiN+TiC+Ti(C,N)/DLC (diamond like carbon), TiN/DLC and TiC/DLC films by plasma-based ion implantation (PBII) with nitrogen, PBII with nitrogen then acetylene, PBII with nitrogen then glow discharge deposition with acetylene plus hydrogen and PBII with acetylene then glow discharge deposition with acetylene plus hydrogen respectively were studied. The corresponding films are found getting dimmer, showing light gold or gold, smoky color (uneven), light red in black (uneven), and graphite black separately. The corresponding film resistivities are given. Antioxidation ability of the titanium nitride film is poor, while the existence of carbon (or carbide) improves the antioxidation ability of the films. Having undergone excellent intermediate transitional region of nitrogen and carbon implantation, the top DLC layer of the TiN+TiC+Ti(C,N)/DLC multilayer are formed after the carbon implantation has the best adhesion with the substrate among all the multilayers. Although microhardness of the samples increases in the order of coatings of titanium nitride, TiN/DLC, TiN+TiC+Ti(C,N)/DLC and TiC/DLC, the TiN/DLC and TiC/DLC multilayers have greater brittleness as compared with other films.

Effect of dissolved components of malachite and calcite on surface properties and flotation behavior

In general,malachite is recovered via sulfidization–xanthate flotation,although many unsatisfactory flotation indexes are frequently obtained as a result of the presence of associated calcite.This phenomenon occurs because the dissolved components of malachite and calcite affect the flotation behavior of both minerals.In this study,the effect of the dissolved components derived from malachite and calcite on the flotation behavior and surface characteristics of both minerals was investigated.Flotation tests indicated that malachite recovery decreased when the calcite supernatant was introduced,while the presence of the malachite supernatant increased the recovery of calcite.Dissolution and adsorption tests,along with zeta potential measurements,X-ray photoelectron spectroscopy,Fourier transform infrared spectrometry,and timeof-flight secondary ion mass spectrometry demonstrated that the Ca species in the calcite supernatant were adsorbed on the malachite surface,which hindered the interaction of Na2S with malachite,thereby resulting in the insufficient adsorption of sodium isoamyl xanthate(NaIX)on the surface of malachite.By contrast,the Cu species in the malachite supernatant were adsorbed on the calcite surface,and they provided active sites for the subsequent adsorption of Na_(2)S and NaIX.

The surface properties of aluminated meso–macroporous silica and its catalytic performance as hydrodesulfurization catalyst support

Aluminated mesoporous silica was prepared by multiple post-grafting of alumina onto uniform mesoporous SiO2 ,which was assembled from monodisperse SiO2 microspheres.Hydrodesulfurization（HDS）catalyst was prepared by loading Ni and Mo active components onto the aluminated uniform mesoporous SiO2 ,and its HDS catalytic performance was evaluated using hydrodesulfurization of dibenzothiophene as the probe reaction at 300℃ and 6.0 MPa in a tubular reactor.The samples were characterized by N2 physisorption,scanning electronic microscopy,Fourier transform infrared spectrum,X-ray diffraction（XRD）,temperature-programmed desorption of ammonia（NH3-TPD）,^27Al nuclear magnetic resonance（^27Al-NMR）and high-resolution transmission electron microscopy（HRTEM）.The results showed that the Si–OH group content of SiO2 was mainly dependent on the pretreatment conditions and had significant influence on the activity of the Ni Mo catalyst.The surface properties of the aluminated SiO2 varied with the Al2O3-grafting cycles.Generally after four cycles of grafting,the aluminated SiO2 behaved like amorphous alumina.In addition,plotting of activity of Ni Mo catalysts supported on aluminated meso–macroporous silica materials against the Al2O3-grafting cycle yields a volcano curve.

Effects of Zr/Ti molar ratio in SO_4^(2-)/ZrO_(2-)TiO_2 calcined at different temperatures on its surface properties and glucose reactivity in near-critical methanol

Effects of Zr/Ti molar ratio in SO42-/ZrO2-TiO2 solid acid catalyst calcined at different temperatures on its surface properties and catalytic activity were thoroughly investigated in this paper. The physicochemical characteristics of prepared samples were determined by N2 adsorptiondesorption, XRD, NH3-TPD and XPS techniques, respectively. It was found that the crystallization temperature of the samples increased after the combination of ZrO2 and TiO2; and phase transformations from the anatase to the rutile of TiO2 species and the tetragonal to the monoclinic of ZrO2 species were effectively suppressed at higher temperature. The sample with a Zr/Ti molar ratio of 3/1 calcined at 450℃ showed the highest surface area and the most acid sites among all the tested samples. The acid site densities of samples were relatively closed to each other if they were calcined at the same temperature, however, decreased with the calcination temperature. The result indicates that the sulfur content in samples is a crucial factor to control the acid site density. Calcining the sample at 650℃ and higher temperatures resulted in a significant desorption of sulfate ion on the samples. The synthesized samples were evaluated as a potential catalyst for glucose conversion under the near-critical methanol conditions （200℃/4 MPa）. The results suggested that the relatively weaker acid sites of the catalyst were more favorable for the accumulation of methyl glucosides, while the moderate acid sites were responsible for the formation of methyl levulinate. The catalytic activity for methyl levulinate production almost increases linearly with the catalyst acid site density. The catalyst deactivation is due to the loss of sulfate ion and the two catalysts with Zr/Ti molar ratios of 3/1 and 1/3 could effectively alleviate the deactivation caused by sulfate solution in the reaction medium and can be reused after calcination with the reuse rate of over 90% in terms of the methyl levulinate selectivity.

Effect of Electrochemical Treatment in Aqueous Ammonium Bicarbonate on Surface Properties of PAN-based Carbon Fibers

The surface properties of PAN-based carbon fibers electrochemically treated in aqueous ammonium bicarbonate before and after treatment were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Dynamic Contact Angle Analysis (DCAA). The results of characterization indicated that the oxygen and nitrogen contents in carbon fiber surface were significantly increased by electrochemical treatment, and amide groups was introduced onto it, which was related with the electrolyte. The AFM photographs illustrated that the roughness of the fiber surface was also increased. The wettibality of the fibers was improved after treatment because the surface energy especially the polar part of it was increased.

Surface properties of nitrogen-ion-implanted TiNi shape memory alloy

X-ray diffraction （XRD）, auger electron spectroscopy （AES）, and X-ray photoelectron spectroscopy （XPS） were used to characterize the surface properties of the N^ ＋-ion-implanted TiNi alloy. There is a high nitrogen content region at the outermost surface of the N^＋-ion-implanted TiNi alloy. The detected nitrogen exists mainly in the form of TiN. Small amounts of Ti305 and TiO2 also exist on the surface of the N^＋-ion-implanted TiNi sample. The modified layer of the N^＋-ion-implanted sample can work as an obstacle layer of the nickel＇s dissolution, which obstructs Ni dissolving from the TiNi surface effectively.

Impact of forcing data and land surface properties on snow simulation in a regional climate model:a case study over the Tianshan Mountains,Central Asia

Snow is a key variable that influences hydrological and climatic cycles.Land surface models employing snow physics-modules can simulate the snow accumulation and ablation processes.However,there are still uncertainties in modeling snow resources over complex terrain such as mountains.This study employed the National Center for Atmospheric Research’s Weather Research and Forecasting(WRF)model coupled with the Noah-Multiparameterization(Noah-MP)land surface model to run one-year simulations to assess its ability to simulate snow across the Tianshan Mountains.Six tests were conducted based on different reanalysis forcing datasets and different land surface properties.The results indicated that the snow dynamics were reproduced in a snow hydrological year by the WRF/Noah-MP model for all of the tests.The model produced a low bias in snow depth and snow water equivalent(SWE)regardless of the forcing datasets.Additionally,the underestimation of snow depth and SWE could be relatively alleviated by modifying the land cover and vegetation parameters.However,no significant improvement in accuracy was found in the date of snow depth maximum and melt rate.The best performance was achieved using ERA5 with modified land cover and vegetation parameters(mean bias=−4.03 mm and−1.441 mm for snow depth and SWE,respectively).This study highlights the importance of selecting forcing data for snow simulation over the Tianshan Mountains.

The Effects of Annealing on the Surface Properties of Titania Films Prepared on Titanium by Micro-Arc Oxidation

Titanium and its alloys are widely used in the aerospace, marine, and biomedical industry due to their unique bulk properties such as high strength-to-weight ratio and melting temperature, good corrosion resistance, and favorable biocom- patibility. However, in some applications, com- ponents made of titanium or titanium alloys exhibit poor wear resistance under stationary or dynamic loading as well as contact corrosion manifested by the relatively negative standard electrode potential （-1.63 V ） . In order to improve the surface properties of titanium and its alloys, several techniques such as PVD （ physical vapor deposition ） /CVD （chemical vapor deposition ） coatings,

Effect of the surface properties of an activated coke on its desulphurization performance

Commercial coke was modified by H2O2 and/or NH3.H2O to obtain an activated coke containing additional oxygen functional groups and/or nitrogen functional groups. The aim of the modification was to enhance the SO2 adsorption capacity of the activated coke. Several techniques, including total nitrogen content measurements, SO2 adsorption, XPS and FTIR analysis, were used to characterize the coke samples. The XPS and FTIR spectra suggest the existence of -CONH2 groups in the H2O2 plus ammonia modified coke. The SO2 adsorption capacity of an activated coke increases slightly with an increase in H2O2 concentration during the modification process. The desulphurization performance of a modified coke is considerably enhanced by increasing the treatment temperature during ammonia modification. The amount of nitrogen in a coke modified by H2O2 plus NH3.H2O is the highest, and the SO2 adsorption capacity of the coke is also the highest (89.9 mg/gC). The NH3.H2O (only) modified sample has lower nitrogen content and lower desulphurization capacity (79.9 mg/gC). H2O modification gives the lowest SO2 adsorption capacity (28.9 mg/gC). The H2O2 pre-treatment is beneficial for the introduction of nitrogen onto the surface of a sample during the following ammonia treatment process.

Study on the surface properties of surface modified silicone intraocular lenses

AIM: To prepare a new-type soft intraocular lens (IOL) that silicone intraocular lenses (IOLs) were modified by surface modification technique to assess IOLs biocompatibility. METHODS: With the technique of ion beam combined with low temperature and low pressure plasma, the surface characteristics of the IOLs including physical and optical properties were determined by the instruments of IOLs resolution, UV/VIS scanning spectrophotometer, contact angle measurement system, electron spectroscopy for chemical analysis (ESCA) and scanning electron microscope (SEM). RESULTS: The color of titanium (Ti) modified IOLs was light yellow and that of titanium nitride (TiN) modified IOLs was light brown. The absorptive degree of ultraviolet rays and the hydrophilicity of the surfaces of modified IOLs were increased, and appeared suitable chemical compositions. The resolution of unmodified and modified IOLs reached normal standard. The surfaces of unmodified and Ti-modified IOLs appeared uniform. The surfaces of TIN-modified IOLs presented fine porcelain structure. CONCLUSION: The optical properties of all IOLs and the surface morphology of the modified IOLs were not affected by modification processes. The surface properties of the modified IOLs were improved.

Effects of Atmospheric DBD Plasma Treatment on the Surface Properties of PAN-Based Carbon Fiber

Plasma treatment has been known as an effective way to improve the surface bonding between the reinforcement material and the matrix, by modifying the surface morphology and the chemical composes of the material. In order to investigate the effects of atmospheric dielectric barrier discharge (DBD) plasma treatment on the surface properties of polyacrylonitrile-based (PAN-based) carbon fiber, atomic force microscope(AFM), X-ray photoelectron spectroscopy(XPS), and contact angle test were introduced to compare different treatment duration. The interfacial adhesion of carbon fiber/epoxy (CF/EP) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. And the tensile strength test and Weibull analysis were carried out to observe whether the etching could affect the strength. The results prove that the DBD plasma improves the surface properties of the carbon fiber. Further, when the treatment time was around 90 s, the roughness and oxygen containing group of the carbon fiber reached the peak values. Also, the fiber showed the best adhesion to the polymer in contact angle test and the optimum interfacial shear strength (IFSS) in fragmentation test. The Weibull analyses of the tensile data revealed no substantial changes in the tensile strength within the treatment time of 180 s.

PREPARATION AND SURFACE PROPERTIES OF ACRYLIC COPOLYMERS CONTAINING FLUORINATED MONOMERS

A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The surface property of the copolymer films was subsequently characterized. The contact angle measurements and energy dispersive analysis of X-ray （EDAX） show that the length and content of perfluoroalkyl side chains in the copolymers are crucial for the preparation of the film with low surface energy. At a given content of fluorinated monomers in the copolymers, the longer the perfluoroalkyl side chain, the larger the water contact angle of the copolymer films will be. On the other hand, the higher the content of fluorinated monomers, the lower the surface energy is. The water contact angle increases with the increase of the fluorinated monomer content and reaches a plateau at 3 wt% of fluorinated monomer content.

Syntheses and Surface Properties of Polyacrylonitrile-based Copolymer Membranes Containing Sugar Moieties

To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN) with 2,2′-azobis-iso-butyronitrile(AIBN) as the initiator in dimethyl sulphoxide(DMSO). It was found that the yield increased with the increase of the initiator concentration and reaction time, while it decreased with the increase of the monomer molar ratio of AG to AN. Raising the AG proportion in the monomer mixture resulted in the increase of the AG content in the copolymer. M_v of the copolymers decreased with increasing the AG monomer fraction in feed. The copolymers were fabricated into dense membranes and their surface properties were studied by means of the water contact angle measurement and platelet adhesion tests. It was found that the static water contact angle on the membrane decreased significantly from 70° to 33° with the increase of the AG content. The adhesive number of platelets on the membrane surface also decreased significantly with increasing AG content in the copolymers. These results demonstrate that the hydrophilicity and biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the copolymerization of acrylonitrile with vinyl carbohydrates.

Deposition of DLC Coating on Biomedical TiNi Alloys by Plasma Based Ion Implantation to Improve Surface Properties

Diamond-like carbon （DLC） films were successfully deposited on Ti- 50.8 at% Ni using plasma based ion implantation （PBII） technique. The influence of the pulsed negative bias voltage applied to the substrate from 12 kV to 40 kV on the microstracture, nano-indentation hardness and Young＇ s modulus, the surface characteristics and corrosion resistant property as well as hemocompatibility were investigated. The experimental resalts showed that C 1 s peak depended heavily on the bias voltage. With the increase of bias voltage, the ratio of sp2 / sp3 first decreased, reaching a minimum value at 20 kV, and then increased. The DLC coating deposited at 20 kV showed the highest hardness and elastic modulus values as a result of lower sp2/sp3 ratio. The RMS values first decreased from 7.202nm（12 kV） to 5.279 nm（20 kV）, and then increased to 11.449 nm（30 kV） and 7.060 nm（ 40 kV）. The uncoated TiNi alloy showed severe pitting corrosion, due to the presence of Cl-ions in the solution. On the contrary, the DLC coated sample showed very little pitting corrosion and behaved better corrosion resistant property especially for the specimens deposited at 20 kV bias voltages. The platelet adhesion test show that the hemocompatibility of DLC coated TiNi alloy is much better than that of bare TiNi alloy, and the hemocompatibility performance of DLC coated TiNi alloy deposited at 20 kV is superior to that of other coated specimens.

Surface modification of wollastonite by the mechano-activated method and its properties

Surface modification of wollastonite particles using titanate as a modification agent incorporated by simultaneous wet ultra-fine grinding in a laboratory stirred mill was investigated.The physical,physic-chemical and application properties of the modified wollastonite were measured and evaluated.The results showed that grinding intensity markedly influences the modification effect because of the mechano chemical effect.The hydrophilic surface of wollastonite was turned into a hydrophobic one after modification.The interaction between titanate and wollastonite under wet grinding circumstances was studied.It was suggested that physical adsorption and chemical adsorption of titanate coexisted on the wollastonite surface.The mechanical properties of polyethylene（PE） filled with the modified wollastonite powder were markedly improved.

Bio-leaching effects of Leptospirillum ferriphilum on the surface chemical properties of pyrite

Leptospirillum ferriphilum cultured using different energy sources(either soluble ferrous ion or pyrite) changed the surface properties of pyrite.Cell adsorption,zeta-potential,hydrophobicty,FT-IR spectra and surface morphology were investigated.Adhesion of bacterial cells to the pyrite surface is a fast process.Furthermore,the adsorption of cells grown in pyrite is greater than of cells grown in soluble ferrous ion.The Iso-Electric Point(IEP) of pyrite treated with L.ferriphilum approaches that of the cells themselves.The contact angle of the pyrite surface was observed to decrease due to the surface formation of some hydrophilic substances during bio-leaching.Changes in pyrite surface properties after bacterial treatment support the idea that ferric ion plays an important role and that indirect bio-oxidation is the principal mechanism of pyrite bio-leaching.

Synthesis, UV-curing Behavior and Surface Properties of New Fluorine-containing Aromatic Oxetane Monomers

In this paper, we combined high-end cationic UV-curable material with fluorinated chain obtaining a series of new fluorine-containing aromatic oxetane monomers via a mild nucleophilic substitution reaction. The structures and properties of monomers were characterized using ~1 H-NMR, ^（19） F-NMR, dynamic viscosity tests and differential scanning calorimetry（DSC）. It was determined that all of the fluorinated monomers obtained had much lower viscosity and higher thermostability after the introduction of hexafluorobenzene. Then, UV-curable coatings were prepared using four fluorine-containing aromatic oxetane monomers（FOX1-4）; the UV-curing kinetics, with three kinds of initiators, and properties of the cured films were evaluated using real-time Fourier transform infrared（FTIR） spectroscopy, water and diiodomethane contact angle tests, surface energy calculations and scanning electron microscopy（SEM）. The FTIR spectroscopy results showed that the coatings possessed excellent conversion rate（〉 99% with liquid initiator PAG-201 in 150 s）, and as the fluorine content increased, the monomers exhibited decreased mobility with the increasing viscosity and worse solubility with fluorinated monomers, resulting in a lower conversion rate. Moreover, the coatings possessed favorable hydrophobic and oleophobic properties and low surface energies owing to the fluoride chains floating to the membrane-air interface, which was also confirmed by discrete concave structures in SEM images. These new kinds of monomers can replace traditional fluorinated cationic monomers applied to the fingerprint resistant, fouling resistant, scratch resistant and anti-aging coatings, adhesives or printing ink materials.