Transpiration surface reduction of Kousa Dogwood trees during serious water imbalance

The response of Kousa dogwood （Cornus kousa Buerg.） to extreme stresses was investigated by RGB image analysis in the hot, dry and windy summer in 2007 in Yamaguch, Japan. Results show that tip and margin leaf scorch was observed on many Kousa dogwood trees and clearly dark brown defense barrier appeared on scorched leaves. The defense barrier withdrew back from distal to proximal gradually until successful control of scorching, and left a series of unsuccessful defense traces. By responsive analysis of leaf color homogeneity with RGB image analysis method, a sharp logistic equation was obtained for the relative green/luminance （RGL） value of scorched leaves. By the meteorological analysis, the occurrence of dogwood leaf scorch-back was almost synchronous with the aridity peak period. It sug- gested that during the sudden aridity increment the extreme water stresses induce the defense response of Kousa dogwood tree to shear the excessive transpiration leaf area, and prevent the rest of the trees from further water loss. Image pixet analysis showed that 40.2% leaf area of sampled dogwood trees was reduced through the partial leaf scorch-back by the end of August in 2007. In contrast, only 13.2% leaf area was reduced from the same trees in 2008, for the reason of sufficient precipitation during first half year. In any case, the Kousa dogwood trees indeed reduced their transpiration surface area and appeared a surface reduction pattern differing from those shedding leaves or withering all the aboveground. Based on desiccation process analysis, it is considered that the interaction of the leaf dried back and the self-defense response was the key of the transpiration surface reduction （TSR） of Kousa dogwood during sudden hot and droughty stresses.

Effects of surface chemical properties of activated coke on selective catalytic reduction of NO with NH_3 over commercial coal-based activated coke

Surface chemical properties of typical commercial coal-based activated cokes were characterized by Xray photoelectron spectroscopy(XPS) and acid-base titration, and then the influence of surface chemical properties on catalytic performance of activated cokes of NO reduction with NH3 was investigated in a fixed-bed quartz micro reactor at 150 ℃. The results indicate that the selective catalytic reduction(SCR) activity of activated cokes with the increase of its surface acidic sites and oxygen content,obviously, a correlation between catalytic activity and surface acidic sites content by titration has higher linearity than catalytic activity and surface oxygen content by XPS. While basic sites content by acid-base titration have not correlation with SCR activity. It has been proposed that surface basic sites content measured by titration may not be on adjacent of acidic surface oxides and then cannot form of NO2-like species, thus the reaction of reduction of NO with NH3 have been retarded.

Reduction of Reactive-Ion Etching-Induced Ge Surface Roughness by SF6/CF4Cyclic Etching for Ge Fin Fabrication

An SF6/CF4 cyclic reactive-ion etching （RIE） method is proposed to suppress the surface roughness and to opti- mize the morphology of Ge fin, aiming at the fabrication of superior Ge FinFETs for future CMOS technologies. The surface roughness of the Ge after RIE can be sufficiently reduced by introducing SF6-O2 etching steps into the CF4-O2 etching process, while maintaining a relatively large ratio of vertical etching over horizontal etching of the Ge. As a result, an optimized rms roughness of 0.9nm is achieved for Ge surfaces after the SF6/CF4 cyclic etching with a ratio of greater than four for vertical etching over horizontal etching of the Ge, by using a proportion of 60% for SF6-O2 etching steps.

S-doped carbon aerogels/GO composites as oxygen reduction catalysts

Composites of carbon aerogel and graphite oxide（GO） were synthesized using a self-assembly method based on dispersive forces. Their surface was modified by treatment in hydrogen sulfide at 650 and800 ℃. The samples obtained were characterized by adsorption of nitrogen, TA-MS, XPS, potentiometric titration, and HRTEM and tested as catalysts for oxygen reduction reactions（ORR） in an alkaline medium.The synergistic effect of the composite（electrical conductivity, porosity and surface chemistry） leads to a good ORR catalytic activity. The onset potential for the composite of carbon aerogel heated at 800 ℃ is shifted to a more positive value and the number of electron transfer was 2e-at the potential 0.68 V versus RHE and it increased to 4e-with an increase in the negative values of the potential. An excellent tolerance to methanol crossover was also recorded.

Influence of an External DC Electric Current on Plasma Cleaning Rate: an Application on the Enlarged Plasma-Surface Theor

During the last decades many researchers have been occupied with other plasma applications apart from the big challenge which the thermonuclear fusion poses. Many experiments have been carried out on the plasma behavior in contact with a solid surface; when the surface material consists of chemical compounds （e.g. oxides of metals）, then the plasma chemistry takes place. The present paper contains the final experimental and theoretical work of Plasma Laboratory at ＂Demokritos＂, which consists of an elaboration of plasma sheath parameters adapted to experimental conditions, a suitable choice of plasma gases （either H 2 or N 2 ）, and an electric po-tential current enforcement on objects. Additionally, a brief theory is given to explain the results, with a short reference to both boundary phenomena in thermonuclear reactors and low pressure plasma of glow discharges, so as to reveal the similarities and differences of these two cases. An extensive examination of the treated objects by X-ray diffraction method （XRD） gives results in agreement with the theoretical predictions. Using this improvement on plasma restoration system, （a combination of electric current on metallic object into suitable plasma）, it is shown that better results can be achieved on the cleaning and conservation of archaeological objects.

The Method and Experiment Research on Down-stroke Abrasive Belt Grinding under Micro Feeding for Noise Reduction Surface

This paper proposes a down-stroke abrasive belt grinding under micro feeding for noise reduction surface.Firstly,a physical model of processing under micro feeding for noise reduction structure was established.Based on the flexible contact characteristics of abrasive belt grinding and Hertz contact theory,a mathematical model suitable for this method was established,considering vibration and abrasive belt wear.Secondly,a simulation analysis was carried out.Then,an experimental platform was built to analyze the influence of process parameters on surface roughness and surface microstructure,with the model verified.Finally,the propeller with pit structure was simulated,and the noise reduction performance of the propeller under this method and general abrasive belt grinding was compared and analyzed.The results show that the maximum error of the model based on proposed method does not exceed 10%,and the coincidence degree of the minimum error point can reach 90%at lower feed speed and higher linear velocity of the abrasive belt.The noise reduction effect of the propeller with pit-shaped surfaces can reach 35%.Through the above analysis,the proposed method can be used for the processing of noise reduction surfaces.

Monitoring the surface evolution of a nanoporous core-shell electrocatalyst for oxygen reduction reaction

Subject Code:E01With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Profs.Ding Yi(丁轶)and Luo Jun(罗俊)from the School of Materials Science and Engineering,Tianjin University of Technology and Prof.Liu Limin(刘利民)from Beijing

Impact of Air Pollution on Summer Surface Winds in Xi’an

By analysis of observation data, this paper demonstrates that pollution particles could reduce surface wind speed through blocking solar radiation to the ground. The comparation between temperature at the lowland meteorological station Xi’an and that over the nearby highland station Mt. Hua suggests that surface solar radiation at Xi’an is reduced due to the increasing anthropogenic aerosols. The reduced surface energy suppresses the atmospheric instability and convective flows, and thus the downward transfer of faster winds aloft is reduced. Consequently, wind speeds near surface are weakened. This reduction of surface winds is shown by the significant reverse trends of wind speeds over the two stations at different elevations. The aerosols’ effects on winds are also manifested in the trends of radionsonde wind speed. The decreased surface winds in Xi’an have also reduced local pan evaporation.

Water-trapping and drag-reduction effects of fish Ctenopharyngodon idellus scales and their simulations

In the last decades, surface drag reduction has been re-emphasized because of its practical values in engineering applications,including vehicles, aircrafts, ships, and fuel pipelines. The bionic study of drag reduction has been attracting scholars' attentions. Here, it was determined that the delicate microstructures on the scales of the fish Ctenopharyngodon idellus exhibit remarkable drag-reduction effect. In addition, the underlying drag-reduction mechanism was carefully investigated. First,exceptional morphologies and structures of the scales were observed and measured using a scanning electron microscope and3-dimensional(3D) microscope. Then, based on the acquired data, optimized 3D models were created. Next, the mechanism of the water-trapping effect of these structures was analyzed through numerical simulations and theoretical calculations. It was determined that there are many microcrescent units with certain distributions on its surface. In fact, these crescents are effective in generating the "water-trapping" effect and forming a fluid-lubrication film, thus reducing the skin friction drag effectively.Contrasting to a smooth surface, the dynamics finite-element analysis indicated that the maximum drag-reduction rate of a bionic surface is 3.014% at 0.66 m/s flow rate. This study can be used as a reference for an in-depth analysis on the bionic drag reduction of boats, underwater vehicles, and so forth.

Relationships between the activities and Ce^(3+)concentrations of CeO_(2)(111)for CO oxidation:A first-principle investigation

CO oxidation at ceria surfaces has been studied for decades,and many efforts have been devoted to understanding the effect of surface reduction on the catalytic activity.In this work,we theoretically studied the CO oxidation on the clean and reduced CeO_(2)(111)surfaces using different surface cells to dete rmine the relationships between the reduction degrees and calculated reaction energetics.It is found that the calculated barrier for the direct reaction between CO and surface lattice O drastically decreases with the increase of surface reduction degree.From electronic analysis,we found that the surface reduction can lead to the occurrence of localized electrons at the surface Ce,which affects the charge distribution at surface O.As the result,the surface O becomes more negatively charged and therefore more active in reacting with CO.This work then suggests that the localized 4 f electron reservoir of Ce can act as the"pseudo-anion"at reduced CeO_(2) surfaces to activate surface lattice O for catalytic oxidative reactions.