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  • 1
    Series available for loan
    Series available for loan
    Kingston : Antarctic Division, Dept. of Science
    Associated volumes
    Call number: ZSP-124-25
    In: ANARE research notes
    Description / Table of Contents: This Research Note details the mathematics behind the development of a program to calculate the impulse function relating two arrays of data. These data arrays are discrete samples of the proposed driving and driven functions. The program is tested for its susceptibility to noise and non-linear variations between the input functions. The impulse function program and relevant test programs are listed and their use described.
    Type of Medium: Series available for loan
    Pages: iv, 42 S. : Ill.
    ISBN: 0642074534
    Series Statement: ANARE research notes 25
    Branch Library: AWI Library
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  • 2
    ISSN: 1615-6102
    Keywords: Date ; Phoenix ; Mannanase ; Mannosidase ; Endosperm ; Germination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The zone of endosperm breakdown in the germinated date seed (Phoenix dactylifera L.) is a narrow area immediately adjacent to the surface of the enlarging cotyledon, or haustorium. The zone width is correlated with the amount of cell division in the adjacent region of the haustorium. The sequence of endosperm breakdown is: 1. protein bodies vacuolate, 2. storage cell walls become electron-transparent immediately adjacent to the protoplast of each endosperm cell, 3. all remaining cytoplasm and lipid bodies disappear, and 4. the remaining cell walls become electron-transparent and collapse against the haustorium surface. Two cell wall hydrolases are present—endo-Βmannanase (EC3.2.1.78) and Β-mannosidase (EC3.2.1.25). Β-mannosidase is detectable in the endosperm before germination. At germination, the major portion of activity is found in the softened endosperm. Β-mannanase is only detectable from germination and there is always hundreds of fold greater activity in the softened endosperm than elsewhere. Proteinase is detectable in trace amounts at germination in the softened endosperm but is also found in the haustorium at later stages. Isolated haustoria, incubated in extracted ivory nut (Phytelephas macrocarpa) mannan in buffer, cause no mannan breakdown. Haustoria, incubated in a solution of locust bean galactomannan, cause no decrease in galactomannan viscosity. Our observations suggest that although haustoria probably regulate mannan breakdown in the endosperm, they do not seem to secrete the hydrolytic enzymes concerned.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2152-2154 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous, 10-nm-thick tantalum-silicon-nitride (TaSiN) layers were found to be effective diffusion barriers between copper and thermal silicon dioxide. The films were electrically evaluated using TaSiN/Cu/TaSiN-oxide-silicon capacitors and bias thermal stress (BTS) treatments; the capacitors were stressed at 300 °C with electric fields in excess of 1 MV/cm for up to 80 h. High frequency capacitance versus voltage characteristics were recorded at room temperature before and after BTS treatment. Based upon comparisons between these (C–V) curves, barrier failure was concluded to have not occurred. © 1995 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 656-663 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Films of Ti-Si-N were synthesized by reactively sputtering TiSi2, Ti5Si3, or Ti3Si targets in an Ar/N2 gas mixture. They were characterized in terms of their composition by MeV 4He backscattering spectrometry, their atomic density by thickness measurements combined with backscattering data, their microstructure by x-ray diffraction and high-resolution transmission electron microscopy, and their electrical resistivity by four-point-probe measurements. All films have a metal–to–silicon ratio close to that of their respective targets. The as-deposited films are either entirely amorphous or contain inclusions of TiN-like nanometer-sized grains when the overall atomic composition of the films approaches the TiN phase in the ternary Ti-Si-N diagram. A correlation between the resistivity of the as-deposited films and their position in the ternary phase diagram is evident, indicating that at the atomic scale, the spatial arrangement of atoms in the amorphous phase and their bonding character can approximate those of the equilibrium phases. A mixture of nanocrystalline TiN and amorphous Si-N is proposed for some titanium- and nitrogen-rich films. The atomic density of some films exceeds 1023 at./cm3. The resistivity of the films increases with the Si and the N content. A thermal treatment in vacuum at 700 °C for 1 h decreases the resistivity of the Ti-rich films deposited from the Ti5Si3 or the Ti3Si target, but increases that of the Si-rich films deposited from the TiSi2 target when the nitrogen content exceeds about 30 at. %. The effectiveness of these films as diffusion barriers between Si and Al or Cu is reported in Part II. © 1997 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 664-671 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ti-Si-N films synthesized by reactively sputtering a TiSi2, a Ti5Si3, or a Ti3Si target in Ar/N2 gas mixture were tested as diffusion barriers between planar (100) Si substrates and shallow n+p Si diodes, and Al or Cu overlayers. The stability of the Ti-Si-N barriers generally improves with increasing nitrogen concentration in the films, with the drawback of an increase in the film's resistivity. Ti34Si23N43 sputtered from the Ti5Si3 target is the most effective diffusion barrier among all the Ti-Si-N films studied. It works as an excellent barrier between Si and Cu. A film about 100 nm thick, with a resistivity of around 700 μΩ cm, maintains the stability of Si n+p shallow junction diodes with a 400 nm Cu overlayer up to 850 °C for 30 min vacuum annealing. When it is used between Al and Si, the highest temperature of stability achievable with a 100-nm-thick film is 550 °C. A thermal treatment at 600 °C causes a severe intermixing of the layers. The microstructure, atomic density, and electrical resistivity of these films are described in an accompanying Part I. © 1997 American Institute of Physics.
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: M–Si–N and M–Si (M=Mo, Ta, or W) thin films, reactively sputtered from M5Si3 and WSi2 targets, are examined as diffusion barriers for aluminum metallizations of silicon. Methods of analysis include electrical tests of shallow-junction diodes, 4He++ backscattering spectrometry, x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and secondary-ion-mass spectrometry. At the proper compositions, the M–Si–N films prevent Al overlayers from electrically degrading shallow-junction diodes after 10 min anneals above the melting point of aluminum. Secondary-ion-mass spectrometry indicates virtually no diffusivity of Al into the M–Si–N films during a 700 °C/10 h treatment. The stability can be partially attributed to a self-sealing 3-nm-thick AlN layer that grows at the M–Si–N/Al interface, as seen by transmission electron microscopy. © 1996 American Institute of Physics.
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  • 7
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two pure, homogeneous xyloglucan-hydrolyzing enzymes from germinated nasturtium seeds have been used to localize xyloglucans specifically in seed cell walls. The enzymes, a novelendo (1→4)-β-d-glucanase which shows absolute specificity towards xyloglucans and a β-d-galactosidase which is capable of removing galactosyl residues from polymeric xyloglucans, were used to stabilize gold sols. The complexes were applied to ultrathin sections of nasturtium (Tropaeolum majus L) and tamarind (Tamarindus indica L) seeds. The gold complexes prepared from the active enzyme proteins retained enzyme activity, and such complexes gave extremely weak section-labelling or no labelling at all. When the enzymes were subjected to heat-deactivation before being used to stabilize the gold sols, gold complexes were obtained which lacked enzyme activity, but which gave strong, specific labelling of xyloglucans in ultrathin sections. The specificity of the labelling was checked by substrate-competition, by pretreatment of sections with the active and heat-denaturated enzymes and by comparing the labelling of xyloglucan-containing storage cells with other cell types in the same section. The labelling was maximal at the pH which was optimal for the active enzyme. We conclude that the enzyme-gold complexes which retain high activity against the substrate to be localized are likely to be unsuitable as cytochemical probes because they may causein situ substrate modification. In the case of the enzyme complexes described here the specific localization obtained with the gold complexes prepared from heat deactivated enzymes may be attributable to the retention by the heat-treated enzymatically-inactive proteins of substrate recognition. Alternatively, some recovery of the native configuration of the heat-denatured protein may have occurred on adsorption to the surface of the colloidal gold particle.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seeds of Trigonella foenum-graecum are examined light microscopically and by chemical analysis at different stages of germination. In the earliest stages of germination the raffinose family oligosaccharides are metabolised both in the endosperm and in the cotyledons of the seed but there is no change in the appearance, amount or composition of the main carbohydrate reserve, a galactomannan localised in the endosperm. About 18 hours after the emergence of the radicle the endosperm galactomannan begins to be mobilised. In a period of 24 hours the polysaccharide is completely degraded and the breakdown products, mainly galactose and mannose, are absorbed by the cotyledons in which sucrose increases and starch is formed. Mobilisation of the galactomannan is accompanied by the formation in the endosperm of a dissolution zone the form of which implies that the aleurone layer is involved in the degradation process.
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  • 9
    ISSN: 1432-2048
    Keywords: Endosperm ; Galactomannan ; α-Galactosidase ; Germination (seed) ; Seed germination ; Trigonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When endosperms were isolated from fenugreek seeds 5 h after sowing and incubated in a small volume of water, the development of α-galactosidase activity and the breakdown of the galactomannan storage polysaccharide were both inhibited relative to control endosperms incubated in larger volumes. The inhibition could be relieved by pre-washing the endosperms, and reimposed by the wash-liquors. If the endosperms were isolated 24 h after sowing, no inhibition was observed. Removal of the embryonic axis from germinating fenugreek seeds and from germinated seedlings also inhibited the development of α-galactosidase activity and galactomannan breakdown in the endosperms; the inhibition was more pronounced the earlier the axis was removed. Axis excision 5 h after sowing caused a delay in the onset of galactomannan breakdown and of the appearance of α-galactosidase activity in the endosperms. It also led to a decrease in the rates of galactomannan breakdown and α-galactosidase production. Axis excision 24 h after sowing caused only a slowing of the rates of galactomannan breakdown and α-galactosidase increase. The inhibition caused by axis removal at 5 h could be relieved partially by gibberellin (10-4 M), benzyladenine (10-5 M), mixtures of these and by the herbicide SAN 9789 [4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridazinone]. These substances had no effect on the inhibition caused by axis-removal at 24 h. Excision of the cotyledons at 5 h-leaving the separated axis and the endosperm-also caused inhibition of galactomannan breakdown and α-galactosidase development. The results are consistent with the presence in the fenugreek seed endosperm of diffusible inhibitors of galactomannan mobilisation which are removed or inactivated during normal germination and early seedling development. They are also consistent with a role for the seedling axis in the control of galactomannan breakdown in the endosperm. Initially the axis appears to have a regulatory function (via gibberellins and/or cytokinins?) in determining the onset of α-galactosidase production in the endosperm. Thereafter its continued presence is necessary to ensure maximal rates of α-galactosidase production and galactomannan hydrolysis. The role of the axis may be initially to counteract the endogenous inhibitors in the endosperm and then to act as a sink for the galactomannan breakdown products released in the endosperm and taken up by the cotyledons.
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  • 10
    ISSN: 1432-2048
    Keywords: Cyamopsis ; Endosperm ; Galacto-mannan biosynthesis ; Galactosyltransferase ; Mannosyltransferase ; Polysaccharide biosynthesis ; Seed development ; Trigonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Particulate enzyme preparations were isolated from developing fenugreek (Trigonella foenum-graecum L.) and guar (Cyamopsis tetragonoloba [L.] Taub.) seed endosperms during the period of galactomannan deposition in vivo. These preparations catalysed the formation of polysacharide products from guanosine 5′-diphosphate (GDP)-mannose, from uridine 5′-diphosphate (UDP)-galactose and from mixtures of the two nucleotides. The products were analysed by solubility, by complete acid hydrolysis, and by selective enzymatic cleavage using pure enzymes of known specificity. With GDP-[U-14C]-d-mannose as substrate and a divalent metal cation (Mg+2, Mn+2, or Ca+2) a highly efficient transfer of labelled d-mannosyl residues was obtained to give a product identified as linear (1→4)-β-linked d-mannan. No transfer of galactosyl residues was obtained when GDP-[U-14C]-d-galactose was the only substrate, although very low and variable amounts of an unidentified product which released labelled glucose on acid hydrolysis were formed. In the presence of UDP-galactose, GDP-mannose and Mn+2 ions, products were formed which have been characterised as galactomanans — a linear (1→4)-β-d-mannan backbone carrying d-galactopyranosyl substituents linked (1→6)-α to mannose. The degree of galactose substitution of the d-mannan backbone was manipulated in vitro by varying GDP-mannose concentrations at constant (saturating) UDP-galactose levels. The transfer of d-galactosyl residues from UDP-galactose to galactomannan was absolutely dependent upon the simultaneous transfer of D-mannosyl residues from GDP-mannose. d-Mannan sequences pre-formed in situ using the mannosyltransferase in the absence of UDP-galactose could not become galactose-substituted in a subsequent incubation either with UDP-galactose alone or with UDP-galactose plus GDP-mannose A model for the interaction of GDP-mannose mannosyltransferase and UDP-galactose galactosyltransferase in galactomannan biosynthesis is proposed.
    Type of Medium: Electronic Resource
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