摘要:

A blue‐green glow was observed in the cold‐plate section of a conventional cryogenic pump used in a vacuum‐deposition chamber. The fluorescence is associated with operation of an electron‐beam evaporator and is present at all gas pressures and evaporator voltages used, but cannot be made to occur during operation of a 1 kV Kaufman‐type ion source or a 3 kV electron source.  

ISSN:0734-2101    

DOI:10.1116/1.578968

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

ISSN:0734-2101    

DOI:10.1116/1.578969

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Based on electric circuits for radio‐frequency plasma reactors it is shown numerically that not only the mean electron density and the mean electron temperature can be determined from the discharge current as described in R. J. Seeböck, R. Deutsch, and E. Räuchle, J. Vac. Sci. Technol. A11, 682 (1993), but also the ratio of the mean electron temperatures in the electrode boundary sheaths can be estimated.  

ISSN:0734-2101    

DOI:10.1116/1.578970

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

ISSN:0734-2101    

DOI:10.1116/1.578971

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A simple pulse‐operated plasma gun, which is a combination of a pulsed‐solenoid valve and an electrode to induce an electric discharge in gas at the outlet is described. The performance of the pulsed‐plasma‐beam gun was tested by carrying out hydrogen‐plasma deoxidization of a GaAs wafer.  

ISSN:0734-2101    

DOI:10.1116/1.578972

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

MicroRaman spectroscopy has been used to measure stress in diamond with improved precision. Stress was induced by rf sputter deposited tungsten films of 1‐ and 9‐μm thickness. Preliminary data showed a systematic error in the diamond Raman peak position of about 0.05 cm−1/scan, which led to inaccurate and imprecise stress measurement. A new technique, using a reference 5520‐Å krypton line only 10.5 cm−1from the Raman diamond line, results in an order of magnitude increase in measurement precision. Using this calibration, diamond peak position could be measured with a precision of ±0.03 cm−1which corresponds to ±11 MPa of stress. This is an easy and inexpensive means to improve stress measurements in diamond by microRaman spectroscopy.

ISSN:0734-2101    

DOI:10.1116/1.578973

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

ISSN:0734-2101    

DOI:10.1116/1.578919

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A computational method was used to calculate the distance‐dependent adsorption energies of three proteins, immunoglobulinFab, trypsin, and lysozyme, on polyethylene, polypropylene, and poly(vinyl alcohol) surfaces. Two different protein orientations for each protein were used to calculate the interaction energy as a function of the separation distance. The programs developed in our laboratory considered van der Waals, electrostatic, and solvation interaction energies. Our computer simulation study suggests that the protein adsorption energy on three polymer surfaces is determined mainly by the relative importance of the attractive van der Waals interaction. The minimum and maximum total adsorption energies calculated in our study were −15.65 kJ/mol for lysozyme on polypropylene and −181.66 kJ/mol for trypsin on polypropylene. The total energy was dependent on the orientation of a protein even on the same polymer surface as expected. The smallest difference between the adsorption energies of the two orientations was 2.03 kJ/mol for trypsin on poly(vinyl alcohol) and the largest difference was 137.93 kJ/mol for lysozyme on poly(vinyl alcohol). Electrostatic and solvation interaction energies showed both attractive and repulsive interaction energies depending on the protein orientation. The simulation study shows that the protein–surface interaction becomes negligible, when the distance between them exceeds 20–30 Å. The distance at which the total interaction energy becomes −2 kJ/mol varied between 9.37 and 24.70 Å for lysozyme on polyethylene and trypsin on poly(vinyl alcohol), respectively. Our results indicate that the grafting of short hydrophilic polymer chains may be enough to prevent protein adsorption.  

ISSN:0734-2101    

DOI:10.1116/1.578920

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Polystyrene‐poly(butadiene‐co‐hydroxylated butadiene)‐polystyrene triblock copolymer (SHBS) with hydrophobic‐hydrophilic microdomain structure has been prepared through the hydroxylation of polybutadiene (PBD) block of anionically polymerized SBS triblock copolymer. X‐ray photoelectron spectroscopic and contact angle measurements revealed that the environmentally induced surface reorganization took place after exposure of the film to water in the case of low degree of hydroxylation of PBD block. The interaction between plasma protein and the SHBS surface has been studied on the basis of transmission electron microscopic observations of the specimen after immersing it in human serum albumin (HSA) and human fibrinogen (HFN) solutions. The adsorbed HSA and HFN were labeled with colloidal gold and the modified PBD block was stained with osmium tetroxide. Thus, the domain recognition of plasma protein can be analyzed. The amount of plasma protein adsorbed per unit area on PS domain did not depend on the degree of hydroxylation of PBD block. However, the amount of plasma protein adsorbed on the hydroxylated PBD block decreased with an increase in degree of hydroxylation. These behaviors can be ascribed to the selective protein adsorption onto hydrophobic phase in order to minimize the interfacial‐free energy between polymer surface and plasma protein solution.

ISSN:0734-2101    

DOI:10.1116/1.578921

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Selective adherence on bioactive glass surfaces of various biological molecules associated with osteogenesis appears to be responsible for the correlation ofinvitroreaction kinetics with the rate of bone bonding. Chemical interaction of organic molecules with hydrated silica is also important in osteogenesis and bone mineralization and affects, in as yet an unknown manner, extracellular bond and cartilage matrix formation. The AM‐1 molecular orbital method is used to calculate the reaction pathways for bond formation between alanine and trisiloxane rings to simulate organic interactions with hydrated silica. The results show that there are low energy reaction pathways for the organic–inorganic bonding. Different types of interfacial bonds can be formed depending upon the structure and orientations of the organic or inorganic molecules. The differences in reaction pathways and binding energies for formation of –Si–O–C– linkages with the amino acids versus formation of –Si–N– bonds may account for the variety of biochemical effects observed for silicon in nature and for bioactive glass.

ISSN:0734-2101    

DOI:10.1116/1.578922

出版商:American Vacuum Society    

年代:1994

数据来源: AIP