PubMed · 5542875
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T Behrendt. 1971. Multiline argon laser.. https://doi.org/10.1001/archopht.1971.00990050357022
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The spectroscopic properties of CuAr, CuAr(+) and CuAr(-) have been studied in detail using ab initio MP2, CCSD and CCSD(T) methods. The effect of basis set on spectroscopic properties of these molecular systems has also been investigated. Among these molecules, CuAr(+) is found to be more strongly bound than CuAr and CuAr(-). The spectroscopic properties of CuAr and CuAr(-) are calculated in Lennard-Jones potential and the spectroscopic properties of CuAr(+) are calculated in Morse potential. Most of the spectroscopic constants of CuAr, CuAr(+) and all the spectroscopic constants of CuAr(-) are first reported. Our calculated bond length, harmonic frequency and dissociation energy of CuAr and CuAr(+) agree very well with the existing theoretical results.
This study investigated the bacterial inactivation/sterilization effects of a new atmospheric plasma source, which is a brush-shaped argon glow discharge created under 1 atm pressure. Such an atmospheric plasma brush requires extremely low power of less than 20 W to operate; and therefore is essentially a low-temperature discharge as confirmed by gas-phase temperature measurements. Two bacteria, Escherichia coli (E. coli) and Micrococcus luteus (M. luteus), seeded in various media were subjected to plasma treatment and their survivability was examined. It was found that such argon atmospheric plasma brush is very effective in destruction of the bacteria cells. With nutrient broth and standard methods agar as supporting media, a cell reduction in a level of 6 orders of magnitude was observed for E. coli within 3-4 min plasma treatment. A similar level of cell reduction was also observed for M. luteus in the two media with 2 or 3 min plasma treatment. The plasma treatment effects on the bacteria cell structures were also examined using scanning electron microscopy and the cell structure damages due to the plasma exposure were observed on both bacteria. The possible sterilization mechanism of the argon plasmas is also discussed in this article.
Micro-implants are increasingly popular in clinical orthodontics to effect skeletal anchorage. However, biofilm formation on their surfaces and subsequent infection of peri-implant tissues can result in either exfoliation or surgical removal of these devices. The present study aimed to assess biofilm formation on five commercially available, surface characterized micro-implant systems in vitro. The elemental surface compositions of as-received and autoclave-sterilized micro-implants were characterized by X-ray photoelectron spectroscopy. High carbon contamination was detected on the oxide surfaces, along with traces of inorganic elements (Ca, Cu, Cr, Pb, Zn, and P) which disappeared after Ar(+) ion sputtering. The mean surface roughnesses (R(a)) were around 182nm for titanium micro-implants, and 69nm for stainless steel micro-implants, as measured by atomic force microscopy. Scanning electron microscopy revealed different surface topographies between manufacturers, varying from typical machined grooves to structural defects like pores and pits. Overnight biofilms were grown on micro-implant surfaces by immersion in pooled human whole saliva. Biofilms on micro-implants treated with chlorhexidine and fluoride mouthrinses contained comparable numbers of viable organisms, but significantly less than did untreated micro-implants. Comparison of different implant systems using multiple linear regression analysis indicated that biofilm formation was governed by roughness of the implant surface and the prevalence of carbon- and oxygen-rich components.