ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Infrared spectroscopy of thin silicon dioxide on silicon (1988)

Olsen, J. E. ; Shimura, F.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 53 (1988), S. 1934-1936

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ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: An infrared technique has been devised to study the structure of very thin films on substrates of high refractive index. Optical spectrum amplification of three orders of magnitude is theoretically available. A series of refractive index enhanced multiple internal reflection spectra reveals a clear thickness-dependent structural transformation in thermal SiO2. The spectra suggest a shift in ring statistics, from smaller to larger, with increasing distance from the oxide-silicon interface.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.100487

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2

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Infrared reflection spectroscopy of the SiO2-silicon interface (1989)

Olsen, J. E. ; Shimura, F.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 66 (1989), S. 1353-1358

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: An infrared reflection technique, devised to study the structure of very thin films on substrates of high refractive index, yields an optical spectrum amplification of three orders of magnitude. With the aid of an infrared polarizer, an unanticipated peak at 1240 cm−1 in the internal reflection spectrum of thin (5–100 A(ring)) thermal SiO2 films on silicon has been identified as a longitudinal optical phonon peak. The unambiguous identification of this peak supports a similar interpretation of the 1230-cm−1 peak in oxygen-containing silicon first proposed by Hu in 1980.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.344435

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3

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A localised decrease of GA1 in shoot tips of Salix pentandra seedings precedes cessation of shoot elongation under short photoperiod (1995)

Olsen, J. E. ; Junttila, O. ; Moritz, T.

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 95 (1995), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: By application of a recently developed method allowing analysis of gibberellins (GAs) in mg amounts of tissue, the effect of photoperiod on levels of GAs in shoot tips of individual seedlings of the woody species Salix pentandra was studied. In elongating long day-grown seedlings, maximum levels of GA1 were found 5–20 mm below the apex, approximately twice the levels in other segments. After exposure of plants to 5 or 15 short days, the levels of GA1 were about 50% lower within this specific region of the stem, as compared with seedlings grown under long days. Short day-induced cessation of shoot elongation also correlated with overall declines in the levels of GA53, GA19, GA20 and GA8, Within each photoperiodic treatment the levels of these GAs were generally relatively similar throughout the upper 35 mm of stems. No differences in internode lengths or in lengths of pith or epidermal cells were found in plants grown under long days compared with those exposed to 5 short days. In both cases, cells in mitosis were observed in the subapical stem tissues of shoot tips. After 15 short days, stem elongation was completed, and dividing cells were generally not found in the subapical part of the stem. However, short day exposure did not prevent elongation of internodes and cells differentiated before the treatment was started. Thus, the localised decrease in level of GA1 in shoot tips under short days precedes the morphological and anatomical changes connected with the short day-induced cessation of elongation growth. This supports the hypothesised role for GA1 in photoperiodic control of shoot elongation in S. pentandra.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb05532.x

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Growth-promoting activity of gibberellins on shoot elongation in Salix pentandra is reduced by 16,17-dihydro derivatisation (1997)

Olsen, J. E. ; Junttila, O.

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 99 (1997), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The metabolism of GA10 is thought to be under photoperiodic control in the woody plant Salix pentandra. However, in a recent study using 16,17-[3H2]GA19 as a mimic of Ga10, no effect of photoperiod was found on its metabolism to 16,17-dihydro-GA20 and 16,17-dihydro-GA1. To investigate if this was due to differential action of exogenous 16,17-dihydro-GAs and GAs, the effects of the 16,17-dihydro-derivatives of the gibberellins GA19, GA1, and GA1 as compared with their parent GAs, on shoot elongation in seedlings of S. pentandra were studied. 16,17-Dihydro-GA19, and -GA20 were both almost inactive, while 16,17-dihydro-GA1 induced some shoot elongation in seedlings treated with ancymidol as well as under short days. GA19, GA20 and GA1 were all able to counteract the inhibitory effect of ancymidol under continuous light, while inhibition induced by a 12-h photoperiod was antagonised only by GA20 and GA1. Thus, the growth-stimulating activity of the tested GAs is significantly reduced by 16,17-dihydro derivatisation, but the derivatives do not inhibit stem elongation in S, pentandra, as has been found in monocotyledons.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb03431.x

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Photoperiodic control of endogenous gibberellins in seedlings of Salix pentandra (1995)

Olsen, J. E. ; Jensen, E. ; Junttila, O. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 93 (1995), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: In the temperate-zone woody species Salix pentandra elongation growth is regulated by the photoperiod. Long days sustain active growth, whereas short days induce cessation of apical growth, which is a prerequisite for winter hardening. It is shown that this is correlated to quantitative changes in levels of endogenous GA19 GA20, and GA1. Within two short days the amount of the active GA1 and its immediate precursor GA20, decreased markedly in young leaves us well as in stem tissue. Also, the amount of GA19, declined, but the decrease was delayed relative to that of GA1 and GA20. The ability of S. pentandra seedlings to respond to exogenous GA19, decreased with increasing numbers of short days. Observations that support the hypothesis that the level of GA1 in S. pentandra is regulated by the photoperiod in a quantitative mode with conversion of GA19, to GA20, being one target for control.Different distribution of GAs in various plant parts was observed. The level of GA was higher in young leaves than in other plant parts, and the amount of GA19 was 5–10 times higher in stem tissue than in leaves and roots. The ratios of GA8 to GA1 and GA20, were higher in roots as compared with other parts, as rods contained very low levels of GA1 and GA20, but amounts of GA20 comparable with other parts.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb05111.x

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Comparison of endogenous gibberellins in roots and shoots of elongating Salix pentandra seedlings (1994)

Olsen, J. E. ; Moritz, T. ; Jensen, E. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 90 (1994), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Gibberellins GA1, GA8. GA19. GA29. GA20 and GA56 (2-epi-GA8). were identified by combined gas chromatography-mass spectrometry in root extracts of elongating Salix pentandra L. seedlings. The presence of GA8 was also demonstrated for the first time in S. pentandra shoots. The levels of GA1, GA8, GA19, GA20 in shoot tissue and in roots were estimated by selected ion monitoring. While the amounts of GA8 and GA19 were similar in both plant parts. the levels of the biologically active GA1 and its immediate precursor GA20. were found to be much lower in roots than in shoots.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb00402.x

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7

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Gibberellins and Subapical Cell Divisions in Relation to Bud Set and Bud Break in Salix pentandra (1999)

Hansen, E. ; Olsen, J. E. ; Junttila, O.

Springer

Journal of plant growth regulation 18 (1999), S. 167-170

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ISSN: 1435-8107

Keywords: Key Words. Bud set—Bud break—Gibberellin—Growth cessation—Photoperiod—Salix pentandra

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract. In young plants of Salix pentandra, a temperate zone deciduous woody species, elongation growth ceases and a terminal bud is formed at day lengths shorter than a critical length. This is the first step in dormancy development, making survival under harsh winter conditions possible. Early studies strongly indicate that gibberellin is involved in the photoperiodic control of bud set and bud break. GA1 action was studied by application under short days to plants where cessation of shoot elongation had occurred, followed by subsequent anatomic investigations of shoot tips. Under short days the frequency of cell division decreased rapidly along with the earlier observed decrease in GA1 levels. Application of GA1 to short-day–induced terminal buds rapidly stimulated cell division in apices several days before visible shoot elongation in response to this treatment was observed. One day after GA1 application a fourfold increase in cell division frequency in apices was observed, increasing to a maximum of sevenfold 2 days after application. Long-day treatment leading to induction of bud break after about 4–6 days was followed by slowly increasing frequency of cell divisions. In earlier studies of this species, short days and gibberellins had no effect on cell elongation. These data show that increased GA1 content, by application or long-day treatment, results in increased frequency of mitosis. This strongly indicates that GA1 affects stem elongation in connection with bud set and bud break primarily by affecting cell divisions in subapical tissues.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/PL00007065

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