A NEW MODEL FOR PHYSICAL ADSORPTION ON SOLID SURFACES

The principal assumptions about equivalence and energy distribution of the asdorption sites on solidsurfaces used by Langmuir for deriving the equation of monomolecular adsorption are generalized and anew physical adsorption model is proposed and tested with experimental data published in literature.Themodels of Langmuir,Freundlich,Temkin etc.are only the special cases.Assuming uniform density distributionof adsorption energy,the isotherm equation is given asn=K.1n[1+（bop）1/Mor n=K.1n[1+（boC）1/M]where n is the amount of adsorption per unit weight or area of solid p or C is tbe pressure of gas or the concen-tration of solution respectively.K,bo,M are constants with physical meanings as described in this paper.This equation can be used over wide range to quantitatively represent the five types of physical adsorptionclassified by Brunauer.

Evaporation of nanoscale water on solid surfaces

The evaporation of water is essential in the macroscopic world.Recent researches show that,on solid surfaces,the evaporation of nanoscale water is quite different from that on bulk water surfaces.In this review,we show the theoretical progress in the study of nanoscale water evaporation on various solid surfaces:the evaporation rate of nanoscale water does not show a monotonic decrease when the solid surface changes from hydrophobic to hydrophilic;the evaporation of nanoscale water on hydrophobic-hydrophilic patterned surfaces is unexpectedly faster than that on uniform surface;the evaporation of nanoscale water on patterned graphene oxide is faster than that on homogeneous one;how temperature affects the evaporation of nanoscale water on solid surface;how ions affect the evaporation of nanoscale water on graphene oxide.

SKEWED SYMMETRY DETECTION OF QUADRIC SURFACE SOLIDS UNDER ORTHOGRAPHIC PROJECTION

The skewed symmetry detection plays an improtant role in three-dimensional（3-D） reconstruction. The skewed symmetry depicts a real symmetry viewed from some unknown viewing directions. And the skewed symmetry detection can decrease the geometric constrains and the complexity of 3-D reconstruction. The detection technique for the quadric curve ellipse proposed by Sugimoto is improved to further cover quadric curves including hyperbola and parabola. With the parametric detection, the 3-D quadric curve projection matching is automatical- ly accomplished. Finally, the skewed symmetry surface of the quadric surface solid is obtained. Several examples are used to verify the feasibility of the algorithm and satisfying results can be obtained.

Structure and dynamics of ordered water in a thick nanofilm on ionic surfaces

The structure and dynamics of water in a thick film on an ionic surface are studied by molecular dynamic simulations. We find that there is a dense monolayer of water molecules in the vicinity of the surface. Water molecules within this layer not only show an upright hydrogen-down orientation, but also an upright hydrogen-up orientation. Thus, water molecules in this layer can form hydrogen bonds with water molecules in the next layer. Therefore, the two-dimensional hydrogen bond network of the first layer is disrupted, mainly due to the 0 atoms in this layer, which are affected by the next layer and are unstable. Moreover, these water molecules exhibit delayed dynamic behavior with relatively long residence time compared with those bulk-like molecules in the other layers. Our study should be halpful to further understand the influence of water film thickness on the interfacial water at the solid-liquid interface.

Study on Free Amino Acid and Short Peptide Fertilizer Production by Solid State Fermented Castor Bean Meal

Using microbial fermentation to increase the content of free amino acids and short peptides in the organic fertilizer for castor bean meal can effectively promote plant growth and improve fruit quality.Using free amino acid and short peptide content as an indicator,through single factor and response surface optimization experiments,the process parameters(moisture content,fermentation time and inoculum quantity)of castor meal solid-state fermentation were optimized.The best process parameters for the solid-state fermentation were:the moisture content 62%,the fermentation time 20 d,and the inoculum quantity 0.23%.The moisture content had the greatest impact on the conversion rate of free amino acids and short peptides,and the protein conversion rate reached 65.6%.The scale-up experiment under the optimal conditions showed that the solid-state fermentation using the inoculum had a significant beneficial effect compared with other fermentation methods.The fermentation of castor cake fertilizer provides a theoretical and practical basis for production feasibility,and has important guiding significance for the effective utilization of castor bean meal.

Evidences of the expanding Earth from space-geodetic data over solid land and sea level rise in recent two decades

According to the space-geodetic data recorded at globally distributed stations over solid land spanning a period of more than 20-years under the International Terrestrial Reference Frame 2008,our previous estimate of the average-weighted vertical variation of the Earth＇s solid surface suggests that the Earth＇s solid part is expanding at a rate of 0.24 ± 0.05 mm/a in recent two decades.In another aspect,the satellite altimetry observations spanning recent two decades demonstrate the sea level rise（SLR） rate 3.2 ± 0.4 mm/a,of which1.8 ± 0.5 mm/a is contributed by the ice melting over land.This study shows that the oceanic thermal expansion is 1.0 ± 0.1 mm/a due to the temperature increase in recent half century,which coincides with the estimate provided by previous authors.The SLR observation by altimetry is not balanced by the ice melting and thermal expansion,which is an open problem before this study.However,in this study we infer that the oceanic part of the Earth is expanding at a rate about 0.4 mm/a.Combining the expansion rates of land part and oceanic part,we conclude that the Earth is expanding at a rate of 0.35 ± 0.47 mm/a in recent two decades.If the Earth expands at this rate,then the altimetry-observed SLR can be well explained.

Fluorescence Microscopic Image Analysis of Nucleic Acids Based on The Capillary Flow Directed Assembly Ring of Neutral Red-nucleic Acid Supramolecular Complexes

It is critical to establish a direct and precise method with a high sensitivity and selectivity in analytical chemistry. In this research, making use of a well known phenomenon of capillary flow, we have proposed an image analysis method of nucleic acids at the price of a small amount of sample. When a droplet of the supramolecular complex solution, formed by neutral red and nucleic acids(NA) under an approximate neutral condition, was placed on the hydrophobic surface of dimethyl dichlorosilane pretreated glass slides, and it was evaporated, the supramolecular complex exhibited the periphery of the droplet due to the capillary effect, and accumulated there to form a red capillary flow directed assembly ring(CFDAR). A typical CFDAR has an outer diameter of (2 r ) about 1.18 mm and a ring width(2 δ ) of about 41 μm. Depending on the experimental conditions, a variety of CFDAR can be assembled. The experimental results are in agreement with our former theoretical discussion. It was found that when a droplet volume is 0.1 μL, the fluorescence intensity of the CFDAR formed by the NR NA is in proportion to the content of calf thymus DNA in the range of 0-0.28 ng, fish sperm DNA of 0-0.24 ng and yeast RNA of 0-0.16 ng with the limit of detection(3 σ ) of 1 7, 1.4 and 0.9 pg, respectively for the three nucleic acids.

Sorption equilibrium moisture and isosteric heat of Chinese wheat bran products added to rice to increase its dietary fibre content

More and more people concern about supplementing dietary food with wheat bran to increase fibre content,but there has been little study of the sorption isotherms and isosteric heats of wheat bran fibre products,which are important to the quality and storage durability of such commodities.This study collected equilibrium moisture content(EMC)and equilibrium relative humidity(ERH)data on six Chinese wheat bran products via the static gravimetric method and analysed their sorption isosteric heats.Results showed that all six wheat bran products had sigmoidal isotherms.The data were best fitted by polynomial,modified GAB,modified Oswin,and modified Halsey models.The relative safe moisture contents of the six wheat bran products were 12.20%–13.86%wet basis(w.b.).The heat of vaporization of wheat bran products approached the latent heat of pure water at around a moisture content(MC)of 22.5%and approximately 2450 kJ/kg.A process of extrusion and ultrafine grinding reduced the solid surface area and sorption isosteric heats of the monolayer,multilayer and condensed water regions in the wheat bran products.In the temperature range of 10–37℃,the EMC of sorption in monolayer,multilayer and condensed water regions decreased with increasing temperature.The milled rice to which 1%–3%200-mesh wheat bran product was added maintained its texture when made into cooked rice and its thermomechanical properties when made into rice dough.After processing by extrusion and ultrafine grinding,wheat bran products have a lower solid surface area and lower monolayer water content(Mm)and sorption isosteric heat values.Some 3%200-mesh wheat bran product can be added to cooked rice for increasing its fibre content and making it more nutritious.

First-principles study of the (001) surface of cubic PbHfO_3 and BaHfO_3

Using first-principles techniques, we investigate the （001） surfaces of cubic PbHfO3 （PHO） and BaHfO3 （BHO） terminated with both AO （A=Pb and Ba） and HfO2. Surface structure, partial density of states, band structure, and surface energy are obtained. The BaO surface is found to be similar to its counterpart in BHO. For the HfO2-terminated surface of cubic PHO, the largest relaxation appears on the second-layer atoms but not on the first-layer ones. The analysis of the structure relaxation parameters reveals that the rumpling of the （001） surface for PHO is stronger than that for BHO. The surface thermodynamic stability is explored, and it is found that both the PbO- and the BaO-terminated surfaces are more stable than the HfO2-terminated surfaces for PHO and BHO, respectively. The surface energy calculations show that the （001） surface of PHO is more easily constructed than that of BHO.

Elastic wave scattering from rough free surfaces of solids

Elastic wave scattering by a rough free surface of solids is analyzed. The analysis is based on the concept of scattering amplitude (SA) and perturbation approximation. The SA method is very convenient for rough surface scattering problems. By solving the boundary equations, the first and the second order solutions of approximate scattering amplitude are obtained. The general solutions are used for, as an example, the wave scattering by rough surfaces with Gaussian distribution. The mean field and variance are given. Finally, an experiment is designed to verify the theoretical predications.

TRACKING METHODS FOR FREE SURFACE AND SIMULATION OF A LIQUID DROPLET IMPACTING ON A SOLID SURFACE BASED ON SPH

With some popular tracking methods for free surface, simulations of several typical examples are carried out under various flow field conditions. The results show that the Smoothed Particle Hydrodynamics （SPH） method is very suitable in simulating the flow problems with a free surface. A viscous liquid droplet with an initial velocity impacting on a solid surface is simulated based on the SPH method, and the surface tension is considered by searching the free surface particles, the initial impact effect is considered by using the artificial viscosity method, boundary virtual particles and image virtual particles are introduced to deal with the boundary problem, and the boundary defect can be identified quite well. The comparisons of simulated results and experimental photographs show that the SPH method can not only exactly simulate the spreading process and the rebound process of a liquid droplet impacting on a solid surface but also accurately track the free surface particles, simulate the free-surface flow and determine the shape of the free surface due to its particle nature.

Fibrinogen Structural Changes Caused by Glass Surface Adsorption Detected by Solid Surface Fluorescence Spectroscopy

Solid surface fluorescence (SSF) spectra of fibrinogen (FG) adsorbed on a glass surface were measured. For comparison, solution fluorescence (SF) spectra of native, thermally denatured, urea denatured FG solution with FG desorbed from a glass surface and the SSF spectra of native FG powder were recorded. To analyze the structural changes induced by the surface adsorption, all the aqueous samples mentioned above were analyzed by circular dichroism (CD) spectroscopy. The results demonstrated that the structural changes of FG induced by glass adsorption caused changes in the spectroscopic features of the SSF spectra, especially in the excitation (EX) spectra. It is suggested that SSF spectroscopy may be a useful tool for studying the structures of surface/interface biomolecules and for evaluating the biocompatibility of biomaterials.

Kinetic study of electrochemically produced hydrogen bubbles on Pt electrodes with tailored geometries

Understanding bubbles evolution kinetics on electrodes with varied geometries is of fundamental importance for advanced electrodes design in gas evolution reaction.In this work,the evolution kinetics of electro-generated hydrogen bubbles are recorded in situ on three(i.e.smooth,nanoporous,and nanoarray)Pt electrodes to identify the geometry dependence.The bubble radius shows a time-dependent growth kinetic,which is tightly-connected to the electrode geometry.Among the three electrodes,the smooth one shows a typical time coefficient of 0.5,in consistence with reported values;the nanoporous one shows a time coefficient of 0.47,less than the classic one(0.5);while the nanoarray one exhibits fastest bubble growth kinetics with a time coefficient higher than 0.5(0.54).Moreover,the nanoarray electrode has the smallest bubble detachment size and the largest growth coefficient(23.3)of all three electrodes.Based on the experimental results,a growth model combined direct bottom-injection with micro-convection is proposed to illustrate the surface geometry dependent coefficients,i.e.,the relationship between geometry and bubble evolution kinetics.The direct injection of generated gas molecules from the bottom of bubbles at the three phase boundaries are believed the key to tailor the bubble wetting states and thus determine the bubble evolution kinetics.

Surface characteristics of Y3Al5O12：Ce^3＋ phosphor with greatly enhanced photoluminescence after chemical defect-selective etching

The surface of a commercial Y3Al5O12：Ce^3＋ phosphor was modified by 99% NH_4F＋CH_3COOH solution in a supersonic bath with water temperature of 80 oC for 4 h. The scanning electron microscopy（SEM） results showed that the edge angles were not as sharp as the unmodified particles and the flat surfaces turned rough with many micro-structures covered. Positron lifetime measurements quantitatively showed that surface defects were removed away by more than 50%. As a result, the photoluminescence determinations showed that the backscatter loss was reduced by 4.2% and the emission power was enhanced by 5.6% after the surface modification. The conversion efficiency was greatly improved from 47.3% to 51.1%, as presented by the fluorescence images. Therefore, it would be greatly helpful for the improvement of efficiency, transparency and stability of pc-LED. Moreover, this method was significantly suitable for mass production due to its easy operation and low cost.