论文在大年三十发表，有点意外。 Lijun Liu, Pingping Li, Li Shen, Yuhong Zou, Kaijie Luo, Fen Zhang, Rong-Chang Zeng , Shuoqi Li. In vitro corrosion and antibacterial performance of polysiloxane and poly(acrylic acid)/gentamicin sulfate composite coatings on AZ31 alloy , Surface and Coatings Technology , Available online8 February 2016, 2016, 291(15): 7-14, doi:10.1016/j.surfcoat.2016.02.016 Highlights • A polysiloxane and LbL composite coating was prepared on AZ31 alloy. • The drug release from the composite coating lasts for 17 days. • The composite coating shows corrosion resistance and antibacterial effect. • It is a versatile approach to develop functional coatings on magnesium implants. Abstract An investigation on the corrosion resistance and antibacterial properties of polyelectrolytes and polysiloxane coatings on magnesium alloy with gentamicin was made. The microstructure and composition of the multilayer coatings were characterized by using Fourier transform infrared spectroscopy, X-ray diffractometer and scanning electron microscopy. The analysis of electrochemical measurement in HBSS suggested that the composite coatingsimproved the corrosion resistance of AZ31 alloy. Finally, the result ofplate-counting method demonstrates the effective antibacterial properties of the functionalized substrates. Thus, it can be concluded that the multilayer-treatment reported here is a versatile approach to develop antibacterial and anticorrosion coatings on magnesium implants. Keywords Magnesium alloy ; Corrosion resistance; Antibacterial performance; Polyelectrolyte; Polysiloxane; Gentamicin
17th Workshop on Dynamical Phenomena at Surfaces (WDPS-17) 17th Workshop on Dynamical Phenomena at Surfaces (WDPS-17) Milan (Italy), September19-21, 2016 http://wdps17.fisica.unimi.it/ Dear colleague, We are pleased to announce the 17th Workshop on Dynamical Phenomena at Surfaces (WDPS-17) to be held next September in Milan (Italy), September 19-21, 2016. The Workshop will be the 17th of a series started in 1983 (SURPHON workshops). Since then it became a regular meeting event for theoretical and experimental surface physicists and chemists along the years. The last two editions took place in Leiden (The Netherlands, 2012) and Madrid (Spain, 2014). The workshop complements traditional topics for the series (growth, vibrations, surface chemistry…) with timely subjects: this edition, emphasis will be on the properties of hybrid organic-inorganic interfaces. Confirmed Invited Speakers: Alessandro Coati, Synchrotron SOLEIL (FR) George Malliaras ENS Mines de Saint Etienne, (FR) Eva Rauls, Universität Paderborn (DE) Stefan Rauschenbach, Max Planck Institute, Stuttgart (DE) Alex Shluger, University College London (UK) Ralf Tonner, Philipps-Universität Marburg (DE) Latha Venkataraman, Columbia University NY (US) Astrid de Wijn, University of Stockholm (SE) In addition to the invited talks the program will include oral contributions as well as poster sessions. Abstract submission and registration will be open from May 2nd to June 19th, 2016. Students and young researchers will be encouraged to apply for local support. Further details and updates are available at the workshop website: http://wdps17.fisica.unimi.it/ We kindly ask you to advertise the workshop in your professional networks and to encourage your colleagues to participate in WDPS-17. The workshop flyer is available at: http://wdps17.fisica.unimi.it/files/WDPS17_flyer.pdf . We hope to see you in Milan next September! With best regards, The organising committee: Guido Fratesi (Università di Milano, Italy) William Allison (University of Cambridge, UK) Giulio Casati (Università dell’Insubria, Italy)
Progresses on microwave remote sensing of land surface parameters Abstract: Highly accurate observations at various scales on the land surface are urgently needed for the studies of many areas, such as hydrology, meteorology, and agriculture. With the rapid development of remote sensing techniques, remote sensing has had the capacity of monitoring many factors of the Earth’s land surface. Especially, the space-borne microwave remote sensing systems have been widely used in the quantitative monitoring of global snow, soil moisture, and vegetation parameters with their all-weather, all-time observation capabilities and their sensitivities to the characteristics of land surface factors. Based on the electromagnetic theories and microwave radiative transfer equations, researchers have achieved great successes in the microwave remote sensing studies for different sensors in recent years. This article has systematically reviewed the progresses on five research areas including microwave theoretical modeling, microwave inversion on soil moisture, snow, vegetation and land surface temperatures. Through the further enrichment of remote sensing datasets and the development of remote sensing theories and inversion techniques, remote sensing including microwave remote sensing will play a more important role in the studies and applications of the Earth systems. microwave remote sensing, soil moisture, vegetation, snow water equivalent, land surface temperature SHI JianCheng, DU Yang, DU JinYang, JIANG LingMei, CHAI LinNa, MAO KeBiao, XU Peng, NI WenJian, XIONG Chuan, LIU Qiang, LIU ChenZhou, GUO Peng, CUI Qian, LI YunQing, CHEN Jing, WANG AnQi, LUO HeJia, WANG YinHui, Progresses on microwave remote sensing of land surface parameters, SCIENCE CHINA Earth Sciences, 2012 Vol. 55 (7): 1052-1078. PDF.pdf
8.2.1 Surface Preparation (In Situ) Surface preparation includes both cleaning and surface modification . Bombardment of the substrate surface by energetic particles prior to the deposition of the film material allows in situ cleaning of the surface (Sec. 12.10). Any surface placed in contact with a plasma will assume a negative potential (sheath potential) with respect to the plasma (self-bias) due to the more rapid loss of electrons to the surface from the plasma compared to the loss of ions to the surface. The sheath potential will accelerate ions across the sheath to bombard the surface . The voltage that develops across the sheath, depends on the flux and energy of the electrons striking the surface. For a weakly ionized DC plasma , the sheath potential will be several volts . Ions accelerated across this sheath potential can desorb adsorbed molecules such as water vapor (“ion scrubbing”). If the ions are of a reactive species , such as oxygen, they will react with contaminant layers, such as hydrocarbons, to produce volatile reaction products and clean the surface. Higher negative sheath potentials can be developed on the substrate surface by accelerating electrons to the surface , applying a DC potential to an electrically conductive surface (applied bias) , or by applying an rf or pulsed DC to an insulating surface . When the potential is high enough for the accelerated inert gas ions from the plasma to attain energies greater than about 100 eV , the ion bombardment can cause physical sputtering that cleans the surface by sputter cleaning . If a chemically reactive species , such as chlorine from CCl4, is present, the surface may be cleaned by plasma etching if a volatile chemical compound is formed by the bombardment. Bombardment can also cause surface modification that can be conducive to film formation. For example, bombardment of a carbide surface by hydrogen ions results in the decarburization of a thin surface layer producing a metallic surface on the carbide, and bombardment from a nitrogen plasma can be used to plasma nitride a steel surface prior to the deposition of a TiN film. Bombardment can also make the surface more “ active ” by the generation of reactive sites and defects. For example, un-bombarded silicon surfaces metallized with aluminum shows no interdiffusion, but the bombarded surface gives rapid diffusion. If done at low bombarding energies , the cleaning of semiconductor materials can be done without introducing surface defects which affect the electronic properties of the surface/interface.
Is the liquid water surface basic or acidic? Macroscopic vs. molecular-scale investigations 摘要 Many physical phenomena are affected by the intrinsic acidity/basicity of the free liquid water surface, yet it remains an active and controversial subject. Macroscopic bubble and droplet experiments have been interpreted to indicate an airwater interface covered with hydroxide, whereas recent molecularscale studies produce the opposite conclusion, viz. that hydroxide is repelled from the interface while hydronium is strongly adsorbed. Here we report results from resonant UV second harmonic generation (SHG) experiments that are best modeled by surface depletion of hydroxide and establish at most a weak surface adsorption. This finding is consistent with our earlier SHG measurements indicating surface enhancement of hydrated protons, as well as with other molecular-scale experiments and simulations, but stands in stark contrast to the results from macroscopic studies. The acidity, or basicity, of aqueous surfaces could strongly influence heterogeneous atmospheric chemical processes, such as aerosol reactions and gas uptake. SHG方法能够从微观的角度研究界面离子浓度，他们研究组之前的UV SHG研究空气水界面的工作中发现了hydrated protons在表面的富集。但是这和一些宏观研究方法的结果似乎有些矛盾。UV SHG可以直接和溶液中的CTTS共振，Hydroxide exhibits a broad charge-transfer-to-solvent (CTTS) transition centered at 187 nm in the bulk ，从而可以研究溶液界面的离子，We have taken a different approach and applied SHG in the UV to directly probe the interfacial ions. At the UV wavelengths used in these experiments, water possesses no resonances, whereas several anions exhibit strong charge-transfer-to-solvent (CTTS) transitions . 本文题目是水的界面是酸性还是碱性？ At 225 nm, the SHG intensity remains constant, within experimental uncertainty, due to the limited concentration range explored. At 200 nm, however, the SHG intensity increases significantly at high bulk concentration. Since such a bulk concentration-dependence increase is not observed at the non-resonant wavelengths, this constitutes a direct measurement of surface hydroxide ions at these high concentrations. However, this does not in itself imply surface enhancement of hydroxide. As described above, a small fraction of hydroxide will always exist at the interface despite a repulsive Gibbs free energy due to thermal fluctuations. 讨论 Our direct experimental support for weak hydroxide and strong hydronium propensities for the water surface agrees with the other molecular-level investigations, as described above, but are in stark contrast to the interpretations of macroscopic bubble and droplet electrophoresis experiments . Those experiments measure the motion of gas bubbles or oil droplets in aqueous solution when an electric field is applied. The motion of the droplets/bubbles is analyzed in terms of their zeta-potential and is interpreted as a measure of the overall charge of the droplet/bubble. For neutral and basic pH, the derived zeta-potential is negative, implying that the droplets and bubbles carry a negative surface charge, and only at low pH is a positive zeta-potential observed, i.e. the isoelectric point is around pH 34. Such findings appear universal for hydrophobic interfaces and have been interpreted as clear evidence for a strong surface enhancement of hydroxide . However, those experiments only show that the bubbles and droplets behave as though they are negatively charged, moving in a solvent bath that would have to be positively charged, and not directly establishing that the outermost liquid layer is covered by hydroxide.
标签: Surface
