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  • 1
    Electronic Resource
    Electronic Resource
    Ultraviolet photoionization in CO2 TEA lasers (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 528-536 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The factors affecting spark ultraviolet (UV) emission and transmission, photoionization, and photoelectron loss mechanisms in CO2 TEA laser gas mixtures have been investigated and compared with the results of other workers. We found two different sources of UV radiation: N2 and an unidentified emitter, postulated to be associated with ionized electrode material; C (from CO and CO2) appeared to have little effect. UV emission was directly proportional to the amount of stored electrical energy in the spark-discharge circuit and to the cube of the peak current produced by the discharge of this energy. The uniformity of preionization produced by two kinds of spark-free space and notched surface guided was examined and the free-space spark was found to be superior. Photoionization was found to be due to the presence of low ionization potential (IP) alkenes in unseeded and fresh gas mixtures and also to NO and NO2 in sealed devices—these were formed as a result of spark plasma reactions. The nature of the photoionization process in NO and C3H6 (an alkene) was investigated; both were ionized in a single-step process. The absorption coefficient for ionizing radiation in CO2 was measured in a gas mixture containing 9% N2 and a N2 free mixture and values of 1.3 and 1.9 cm−1 atm−1 were obtained. It is thought that this may be due to changes in the spark UV emission spectrum when N2 is present. The loss of photoelectrons by third body attachment to NO, NO2, and O2 was monitored and only the attachment to O2 was found to be significant. However, the oxides of N can play a dominant role in the subsequent negative ion reactions on a millisecond timescale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341992
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  • 2
    Electronic Resource
    Electronic Resource
    Experimental investigations on an x-ray preionizer test bed (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 537-543 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An experimental test bed has been used to extensively investigate the operating characteristics of various types of cathode and anode in an x-ray preionizer. The temporal development, intensity, and uniformity of x-ray beams generated by a carbon fiber cold cathode and corona plasma cathode were measured and compared. Electron densities of 〉108 cm−3 in N2 (1 atm) and 〉109 cm−3 in Ar (1 atm) could be generated. Factors affecting the high repetition rate operation of both cathodes were examined. The effect of transmitting target material and thickness on x-ray output were investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342478
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  • 3
    Electronic Resource
    Electronic Resource
    Gas-Liquid Chromatography of Amino Acid Derivatives (1961)
    s.l. : American Chemical Society
    Analytical chemistry 33 (1961), S. 669-673 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac60174a007
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  • 4
    Electronic Resource
    Electronic Resource
    Development of a long life, 2 kHz repetition rate X-ray preionizer (1993)
    Springer
    Applied physics 56 (1993), S. 201-208 
    Details
    ISSN: 1432-0649
    Keywords: 52.80.Vp ; 52.25.Ps
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A simple and rugged X-ray preionizer system has been developed that is capable of sustained operation at the 2 kHz level with a demonstrated lifetime of2.5× 108 shots and a potential lifetime of 〉109 shots. At the heart of the system is an advanced form of corona plasma cathode. Cathode wear is minimised by utilising adsorbates from the dielectric surface and not cathode material to form the surface discharge from which the electron beam is extracted. The preionizer chamber background pressure (which is directly proportional to the sticking rate of adsorbates) is found to be of crucial importance in maintaining good cathode emission at high repetition rates. The device emits a rectangular X-ray beam, 5 cm×40 cm, with an X-ray risetime of 20 ns, a FWHM of 60 ns, and a peak energy of 95 keV. Ionization levels of 〉107 cm−3 in 1 atm of Ne could be generated after the X-rays had passed through 2 mm of aluminium and 1 mm of steel. Good beam uniformity and reproducibility at 2 kHz were shown to be maintained with the aid of a segmented electrode charge collection chamber. The system should be especially suitable for preionizing lasers containing a strongly electron attaching gas mixture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348627
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  • 5
    Electronic Resource
    Electronic Resource
    Identification of the origins of photoionisation in CO2 TEA lasers (1984)
    Springer
    Applied physics 33 (1984), S. 1-5 
    Details
    ISSN: 1432-0649
    Keywords: 42.55 Dk ; 33.80 eH ; 52.80-s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In sealed CO2 spark preionised lasers the preionisation is largely due to photoionisation of NO and NO2, in seeded TEA lasers it originates from the low ionisation potential additive used. Unseeded and flowing gas lasers can still be successfully preionised but the source of this preionisation has remained a mystery; previous attempts to isolate and identify low I.P. gaseous impurities have failed. We have now identified these, using a combination of cryogenic impurity concentration and mass spectroscopy and found them to be a complex mixture of hydrocarbons (C2−C7). Of these hydrocarbons, the alkenes are found to be predominantly responsible for the photoionisation and are present in concentrations of ∼ 0.5 ppm. Deliberate addition of one of these alkenes, propene, to a uv preionised CO2 TEA laser was found to enhance the lasers performance at high energy loadings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690018
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  • 6
    Electronic Resource
    Electronic Resource
    An X-ray preionised self sustained discharge HF/DF laser (1996)
    Springer
    Applied physics 63 (1996), S. 565-573 
    Details
    ISSN: 1432-0649
    Keywords: 4255K ; 4260B ; 51.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report the design and characterisation of a flash X-ray preionised, transversely excited HF/DF laser with energy outputs at the joule level. The laser used a H2/D2: SF6 mixture at a pressure of around 120 Torr. X-ray photon fluxes and ionisation rates in the laser gas are presented and the laser dependence on these examined. It is shown that X-ray preionisation can be effective and it is estimated that the laser should operate satisfactorily with as little as 5% of the total stored electrical energy in the preionisation circuit. The laser performance is comparable to that of a UV preionised device with similar operating parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01830995
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  • 7
    Electronic Resource
    Electronic Resource
    An X-ray preionised self sustained discharge HF/DF laser (1996)
    Springer
    Applied physics 63 (1996), S. 565-573 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 4255K; 4260B; 51.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract.  We report the design and characterisation of a flash X-ray preionised, transversely excited HF/DF laser with energy outputs at the joule level. The laser used a H2/D2: SF6 mixture at a pressure of around 120 Torr. X-ray photon fluxes and ionisation rates in the laser gas are presented and the laser dependence on these exami- ned. It is shown that X-ray preionisation can be effective and it is estimated that the laser should operate satisfactorily with as little as 5% of the total stored electrical energy in the preionisation circuit. The laser performance is comparable to that of a UV preionised device with similar operating parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01830995
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  • 8
    Electronic Resource
    Electronic Resource
    Inheritance of a gene for resistance to tomato spotted wilt virus (TSWV) from Lycopersicon peruvianum Mill (1991)
    Springer
    Euphytica 59 (1991), S. 9-17 
    Details
    ISSN: 1573-5060
    Keywords: Dominant gene ; ELISA ; genetics ; Lycopersicon esculentum ; Lycopersicon peruvianum ; tomato ; TSWV ; virus resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Inheritance of resistance to tomato spotted wilt virus (TSWV) derived from the cultivar ‘Stevens’ was studied. Five TSWV isolates, which differ in geographic origin and elicit different symptoms on tomato, were used to screen the resistant parent plants. Enzyme-linked immunosorbent assay (ELISA) was used to distinguish healthy and infected plants. Two susceptible advanced breeding lines were crossed with four F4 plants of a ‘Stevens’ × ‘Rodade’ obtained from South Africa (SA). There were no differences in the progeny responses of the four SA parents to TSWV. The inheritance of TSWV resistance was found to be a single dominant gene. The SA, F1, and the backcrosses to the resistant parent were found to have eight out of 612 plants infected four months after the inoculations, which indicates a 98.7% penetrance of the resistance gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025356
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  • 9
    Electronic Resource
    Electronic Resource
    Generation means analysis of right-censored response-time traits: Low temperature seed germination in tomato (1990)
    Springer
    Euphytica 48 (1990), S. 239-244 
    Details
    ISSN: 1573-5060
    Keywords: Lycopersicon esculentum ; tomato ; cold tolerance ; seed germination ; genetic analysis ; missing data ; response-time data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In studies to determine the inheritance of response-time traits, such as time to seed germination, some viable individuals may fail to respond during an experiment. If these right-censored observations are ignored, sample means and variances will be underestimated. This is illustrated using data from time to seed germination at 9°C for Lycopersicon esculentum (Mill.) fast germinating PI 120256, slow-germinating T3 and their reciprocal F1, F2 and backcross progeny. This paper presents methods to detect and to accommodate right-censored data in generation means analysis. Genetic interpretations derived from corrected and uncorrected estimates of generation means and variances are compared. Correction for right-censoring increased estimates of environmental and phenotypic variances, and decreased heritability estimates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023656
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  • 10
    Electronic Resource
    Electronic Resource
    Improvement of tomato flavor by genetically increasing sugar and acid contents (1983)
    Springer
    Euphytica 32 (1983), S. 845-855 
    Details
    ISSN: 1573-5060
    Keywords: Lycopersicon esculentum ; tomato ; flavor ; sensory evaluation ; soluble solids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Advanced high sugar and acid breeding lines of tomatoes (Lycopersion esculentum Mill.) were rated higher in sweetness, sourness and overall flavor intensity than the standard cultivars Cal Ace or T3. Titratable acidity and soluble solids content were major contributors to differences in overall flavor intensity. The results demonstrate that significant improvement in tomato flavor can be attained by increasing sugar and acid contents in tomato fruits by genetic manipulation. Current evidence indicates that breeding for high soluble solids in horticulturally acceptable tomato cultivars is justified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042166
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