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51.
MJ Singh DO Kataria N Madhavan P Sugathan JJ Das DK Awasthi AK Sinha R Shanker 《Pramana》1999,53(4):743-764
A projectile ion-recoil ion coincidence technique has been employed to study the multiple ionization and the charge transfer
processes in collisions of 60–120 MeV Si
q+ (q = 4−14) ions with neutral argon atoms. The relative contribution of different ionization channels, namely; direct ionization,
electron capture and electron loss leading to the production of slow moving multiply charged argon recoil ions have been investigated.
The data reported on the present collision system result from a direct measurement in the considered impact energy for the
first time. The total ionization cross-sections for the recoil ions are shown to scale as q
1.7/E
p
0.5
, where E
p is the energy in MeV of the projectile and q its charge state. The recoil fractions for the cases of total- and direct ionizations are found to decrease with increasing
recoil charge state j. The total ionization fractions of the recoils are seen to depend on q and to show the presence of a ‘shell-effect’ of the target. Further, the fractions are found to vary as 1/j
2 upto j = 8+. The average recoil charge state 〈j〉 increases slowly with q and with the number of lost or captured electrons from or into the projectile respectively. The projectile charge changing
cross-sections σ
qq′ are found to decrease with increasing q for loss ionization and to increase with q for direct-and capture ionization processes respectively. The physics behind various scaling rules that are found to follow
our data for different ionization processes is reviewed and discussed. 相似文献
52.
Matthias Westerhausen Christin Birg Holger Piotrowski Tassilo Habereder Max Suter Heinrich Nth 《无机化学与普通化学杂志》2001,627(5):882-890
Formation of Alkaline Earth Metal‐Arsenic Cages via the Metalation of Triisopropylsilylarsane with Calcium, Strontium, and Barium Bis[bis(trimethylsilyl)amide] in Tetrahydrofuran The metalation of triisopropylsilylarsane with the alkaline earth metal bis[bis(trimethylsilyl)amides] in tetrahydrofuran yields the THF complexes of calcium ( 1 ), strontium ( 2 ), and barium‐bis(triisopropylsilylarsanide) ( 3 ). Dissolving of these compounds in toluene leads to the elimination of triisopropylsilylarsane and the formation of the THF complexes of tetraalkaline earth metal hexakis(triisopropylsilylarsanide)‐triisopropylsilylarsanediide of calcium ( 4 ), strontium ( 5 ), and barium ( 6 ), respectively. The central polyhedron of compound 4 can be described as two trigonal bipyramids with the metal atoms in apical positions, connected via the arsanediide substituent as a common corner. The central moieties of the compounds 5 and 6 consist of four trigonal bipyramids which are connected by common edges as well as common faces. 相似文献
53.
Surface spline interpolation when the domain is all of Rd isknown to converge much faster to the data function f than inthe case when the domain is the unit ball. This difference isunderstood to be due to boundary effects which, as will be shown,also affect the size of the surface spline's coefficients. Wepropose a modified form of surface spline interpolation which,to a great extent, overcomes these boundary effects. This modifiedsurface spline interpolant uses only the values of f at thegiven interpolation points. 相似文献
54.
Quantification of veterinary antibiotics (sulfonamides and trimethoprim) in animal manure by liquid chromatography-mass spectrometry 总被引:22,自引:0,他引:22
Haller MY Müller SR McArdell CS Alder AC Suter MJ 《Journal of chromatography. A》2002,952(1-2):111-120
A fast and cost effective method was developed to extract and quantify residues of veterinary antimicrobial agents (antibiotics) in animal manure by liquid-liquid extraction and liquid chromatography-mass spectrometry. The compounds investigated include six sulfonamides, one metabolite, and trimethoprim. The method was performed without sample clean up. Recoveries from spiked manure slurry samples (spike level = 1 mg/kg) were as follows: sulfaguanidine (52%), sulfadiazine (47%), sulfathiazole (64%), sulfamethazine (89%), its metabolite N4-acetyl-sulfamethazine (88%), sulfamethoxazole (84%), sulfadimethoxine (51%), and trimethoprim (64%). Relative standard deviations of the recoveries were less than 5% within the same day and less than 20% between days. The limit of quantification was below 0.1 mg/kg liquid manure slurry for all compounds and calibration curves obtained from extracts of spiked samples were linear up to a level of 5 mg/kg liquid manure, except for trimethoprim (0.01-0.5 mg/kg). Analysis of six grab samples taken in Switzerland from manure pits on farms where medicinal feed had been applied revealed total sulfonamide concentrations of up to 20 mg/kg liquid manure. 相似文献
55.
B. Betev J. J. Blaising P. Bordalo A. Boumediene L. Cerrito A. Degré A. Ereditato S. Falciano K. Freudenreich E. Gorini M. Guanziroli H. Hofer P. Juillot L. Kluberg P. Lecomte P. Le Coultre R. Morand B. Mours A. Romana R. Salmeron P. Strolin H. Suter V. L. Telegdi J. Varela G. Viertel J. Wallace-Hadrill M. Winter NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1985,28(1):15-22
56.
A H Suter 《The Journal of the Acoustical Society of America》1985,78(3):887-900
The study was designed to test the validity of the American Academy of Ophthalmology and Otolaryngology's (AAOO) 26-dB average hearing threshold level at 500, 1000, and 2000 Hz as a predictor of hearing handicap. To investigate this criterion the performance of a normal-hearing group was compared with that of two groups, categorized according to the AAOO [Trans. Am. Acad. Ophthal. Otolaryng. 63, 236-238 (1959)] guidelines as having no handicap. The latter groups, however, had significant hearing losses in the frequencies above 2000 Hz. Mean hearing threshold levels for 3000, 4000, and 6000 Hz were 54 dB for group II and 63 dB for group III. Two kinds of speech stimuli were presented at an A-weighted sound level of 60 dB in quiet and in three different levels of noise. The resulting speech recognition scores were significantly lower for the hearing-impaired groups than for the normal-hearing group on both kinds of speech materials and in all three noise conditions. Mean scores for group III were significantly lower than those of the normal-hearing group, even in the quiet condition. Speech recognition scores showed significantly better correlation with hearing levels for frequency combinations including frequencies above 2000 Hz than for the 500-, 1000-, and 2000-Hz combination. On the basis of these results the author recommends that the 26-dB fence should be somewhat lower, and that frequencies above 2000 Hz should be included in any scheme for evaluating hearing handicap. 相似文献
57.
58.
59.
60.
The 5-Phenylpenta-2,4-dienaldehydes 4 , and 7 , show an uncatalized cis-trans-isomerization of the 4,5-double bond above 70 °C. The negative value of the activation entropy for these reactions points to the formation of the bicyclic valence isomeric 2H-Pyrans 5 and 8 respectively in the rate determining step. Intermediate 5 can be trapped as its tetracyanoethylene cycloadduct 11 . The cis-trans isomeric 1,6-diphenyl-hexa-1,3,5-trienes 12a and 12b undergo above 150° a disrotatory ring closure to the bicyclic dienes 13 and 14 respectively. 相似文献