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  • 1
    Electronic Resource
    Electronic Resource
    Boiling, colloid nucleation and aggregation, and the genesis of bonanza Au-Ag ores of the sleeper deposit, Nevada (1995)
    Springer
    Mineralium deposita 30 (1995), S. 199-210 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A deep “parent” composition for bonanza oreforming fluids at the Sleeper deposit was calculated by the computer program SOLVEQ using fluid-inclusion microthermometric and gas data, and by assuming equilibrium with the following minerals present in vein samples below the bonanza zones: gold, chalcedony, adularia, pyrite, chalcopyrite, and acanthite. The calculated dissolved gold content of 295 ppb is approximately 2 orders of magnitude higher than that assumed for typical geothermal systems. Thus, a gold-enriched fluid appears to have been a principal factor in the genesis of bonanza Au-Ag ores at the Sleeper deposit. Geochemical modelling of possible ore-forming processes using the computer program CHILLER, with the reconstructed ore-forming solution as a starting composition, indicates that boiling most closely reproduces observed minerals and their relative abundances in bonanza ores. The constraint imposed by the association of amorphous silica with gold precludes all of the mixing scenarios modelled, such as mixing with cold and steam-heated groundwaters (acid-sulfate, CO2-rich). Modelling indicates that boiling of a gold-rich deep solution leads to rapid gold precipitation, and that the amount of gold precipitated initially is large relative to other minerals. These factors apparently led to nucleation of colloidal gold particles instead of in-situ gold deposition or coprecipitation with other phases. Gold colloids apparently were entrained in the upward-flowing hydrothermal solutions and grew as they travelled. Upon reaching a critical size (10–100 nm?), they were deposited due to orthokinetic aggregation at an elevation and temperature at which amorphous silica was nucleating and aggregating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196356
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  • 2
    Electronic Resource
    Electronic Resource
    A comparison between propranolol, practolol and betaxolol (SL75212) on the circulatory and metabolic responses to insulin-induced hypoglycaemia (1981)
    Springer
    European journal of clinical pharmacology 21 (1981), S. 177-184 
    Details
    ISSN: 1432-1041
    Keywords: propranolol ; practolol ; betaxolol ; hypoglycaemia ; free fatty acids ; glycerol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 1. Six healthy male volunteers received equivalent intravenous beta-blocking doses of propranolol, practolol and betaxolol (SL75212) or saline at weekly intervals Sixty minutes later 0.1 unit/kg insulin was given intravenously. 2. In all studies, maximum hypoglycaemia (mean 1.2 mmol/l) was reached thirty minutes after insulin. Recovery from hypoglycaemia was delayed with propranolol but practolol and betaxolol had no effect. 3. Propranolol blocked the tachycardia and widening of pulse pressure seen in saline treated subjects. It also blocked the rebound rise in free fatty acids (FFA) and glycerol concentrations that followed the nadir of hypoglycaemia. 4. Neither practolol nor betaxolol had significant effects on pulse rate or blood pressure but betaxolol resembled propranolol in blocking the rebound rise in FFA and glycerol, while practolol blocked the rise in glycerol alone. 5. The magnitude of the rise in growth hormone following hypoglycaemia was similar in all groups, but the peak was earlier after practolol and betaxolol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627917
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  • 3
    Electronic Resource
    Electronic Resource
    Constant-volume pressure measurements on BCC solid3He (1986)
    Springer
    Journal of low temperature physics 62 (1986), S. 67-109 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements have been made of the pressure of the bcc phase of solid3He at molar volumes from 24.2 to 23.2 cm3 and at temperatures from 25 to 0.5 mK. The solid undergoes an unusual antiferromagnetic ordering at a temperature that depends strongly on the sample density. This ordering is due to the unusually large exchange interaction in solid3He, a factor of 104 stronger than the nuclear dipole-dipole interaction. The large latent heat associated with the first-order transition has constrained the size of the sample. The pressure of 0.005 cm3 of solid3He has been measured while the volume of the experimental cell was regulated to within 15 parts in 106. The results provide information on the magnitudes and molar volume dependences of the exchange rates, and suggest that a single physical process governs all aspects of the ordering transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681321
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  • 4
    Electronic Resource
    Electronic Resource
    Middle-ear development (1994)
    Springer
    Journal of comparative physiology 174 (1994), S. 103-110 
    Details
    ISSN: 1432-1351
    Keywords: Middle ear ; Auditory development ; Mouse ; Laser interferometry ; Umbo velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Laser interferometry was used to measure umbo velocity in the developing BALB/c mouse middle ear at 133 pure-tone frequencies between 2.0 kHz and 40.0 kHz, all at a constant 100 dB sound pressure level. Umbo velocities increased with age across the entire frequency range, and reached adult-like levels by about 19 days between 2.0 and 22.0 kHz. Velocities at 28.0 and 34.0 kHz took 27 and 52 days respectively to reach adult-like levels. A simple middle-ear model utilizing compliance, resistance, and inertia elements matched the general trends of our velocity results and provided an indication of the anatomical basis for the growth in umbo velocity. The model suggested that velocity development at the lowest frequencies may be attributed to increases in tympanic membrane compliance. The model also indicated that both the frictional resistance of the middle ear and the inertia of the tympanic membrane and ossicles decreased during the growth period. At frequencies below 20.0 kHz, age-related increases in umbo velocity coincided with improvements in Nj1 thresholds recorded from the round window and evoked potential thresholds obtained from the cochlear nucleus. These results indicated that the functional development of the middle-ear plays a major role in the development of hearing in the mouse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192011
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  • 5
    Electronic Resource
    Electronic Resource
    Stiffness changes in chick hair bundles following in vitro overstimulation (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 727-735 
    Details
    ISSN: 1432-1351
    Keywords: Chicks ; Auditory threshold shift ; Basilar papilla ; Water jet ; Hair cell micromechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. The in vitro effect of intense stimulation on the micromechanical stiffness of hair cell sensory hair bundles was studied at three locations on the chick basilar papilla. Threshold levels of hair bundle motion, produced by a water jet stimulus, were examined before and after exposure to a 300 Hz water jet stimulus set at 25 dB above the pre-exposure threshold level. 2. Threshold levels of motion were systematically examined in 8 unexposed control cells. The level of water jet stimulus needed to achieve the detection threshold of motion remained constant in these cells when periodically tested over a 36.5-min interval. 3. Post-exposure changes in the motion detection threshold of hair bundles were examined in 82 hair bundles, and a number of effects were identified: 2.4% of the hair bundles showed no threshold change; 31.7% of the hair bundles had threshold shifts which indicated an increase in stiffness; 18.3% exhibited a threshold shift that indicated a decrease in hair bundle stiffness, but with no recovery; and 47.6% had thresholds that indicated a decrease in hair bundle stiffness with recovery to pre-exposure levels within 16–18 min. 4. The results suggest that chick hair bundles exhibit complex and varied responses to overstimulation which are very different from that seen in the mammal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192621
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  • 6
    Electronic Resource
    Electronic Resource
    Morphogenetic effects of 2,4-dichlorophenoxyacetic acid on pinto bean (Phaseolus vulgaris L.) leaf explants in vitro (1987)
    Springer
    Plant cell reports 6 (1987), S. 46-49 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Roots, callus and/or globular structures were produced on primary leaf and distal cotyledon explants of pinto bean (Phaseolus vulgaris L. cv. UI 114) cultured on semisolid MS medium with a wide range of 2,4-D concentrations (0.01 to 80 mg/L) with either 0 or 1.0 mg/L kinetin. Explants rooted at lower 2,4-D concentrations than at those favoring globule formation on callus, although roots, callus and globules often developed from the same explant. Isolated opaque green globular structures developed when callus initiated on media with 3 or more mg/L 2,4-D was subcultured in liquid MS + 30 mg/L 2,4-D. These structures multiplied with a fresh weight doubling time of 8–9 days in MS + 30 mg/L 2,4-D. Although this multiplicative behavior and opaque color were reminiscent of embryoids reported for other species, no cotyledons or roots were seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269737
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  • 7
    Electronic Resource
    Electronic Resource
    Hormone-free medium will support callus production and subsequent shoot regeneration from whole plant leaf explants in some sugarbeet (Beta vulgaris L.) populations (1989)
    Springer
    Plant cell reports 8 (1989), S. 222-225 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sugarbeet plants representing 14 of 16 germplasm sources (4 to 5 plants per source) produced callus from leaf disks on a hormone-free Murashige and Skoog based medium. Overall, 49.2% of explants from partially expanded leaves of whole plants initiated callus (53 of 74 plants tested), in an average time of 96.7 days. The time to callus was considerably longer than the 4–6 weeks observed when 1 mg/L N6-benzyladenine has been used in the medium. Shoots were regenerated on the hormone-free medium without subculture from callus of eight individual genotypes, representing 3 of the 14 populations that produced callus. Shoots produced by ‘Gartons White Knight’ and ‘L53’ appeared to be of somatic embryo origin. Rhizogenic calli were also produced by the same three populations that regenerated shoots. Significant differences among populations were found for frequency of root formation from leaf disks and time to callus. Variation among plants within a population was significant for four of the five traits examined. The results indicate the ease of hormone autonomization in sugarbeet, and should be of value in designing regeneration media for a wider range of beet germplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00778538
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  • 8
    Electronic Resource
    Electronic Resource
    Somatic hybridization between the zinc accumulator Thlaspi caerulescens and Brassica napus (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 761-771 
    Details
    ISSN: 1432-2242
    Keywords: Key words Electrofusion ; AFLP DNA analysis ; Somatic fusion ; Phytoremediation ; Metal toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Somatic hybrids between the zinc hyperaccumulator Thlaspi caerulescens and Brassica napus were produced by electrofusion of protoplasts isolated from each species. Optimization of electrofusion parameters yielded interspecies heteroplasmic fusion rates of up to 13%. Hybrids were selected by screening the growing calli for Zn tolerance. In addition, a second novel selection technique was developed based on the observation that a high proportion of hybrid microcalli grown in liquid media did not adhere to the wall of the culture vessel, while microcalli derived from parental cells did. Seventeen from a total of 64 regenerated plants were conclusively verified as hybrids by AFLP DNA analysis. The hybrid plants were grown in soil for up to 4 months, and at least five flowered. Several of these hybrids survived when grown on high-zinc media.These hybridsaccumulated levels of zinc and cadmium that would have been toxic for B. napus. The data indicate that transfer of the trait for metal hyperaccumulation in plants is possible through somatic hybridization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051295
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  • 9
    Electronic Resource
    Electronic Resource
    Schwer brennbare Nylon-Teppiche (1977)
    Springer
    Colloid & polymer science 255 (1977), S. 624-624 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01549890
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  • 10
    Electronic Resource
    Electronic Resource
    Cloning and expression of penicillin acylase genes from overproducing strains of Escherichia coli and Bacillus megaterium (1987)
    Springer
    Applied microbiology and biotechnology 25 (1987), S. 372-378 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Penicillin acylase genes from Escherichia coli 194, of an overproducing mutant (194-3) of this strain, and of a similar overproducing mutant of Bacillus megaterium UN1 were cloned in E. coli DH1 on the plasmid vector pACYC184. The sizes of chromosomal DNA fragments essential for penicillin acylase production were found by Tn1000 mutagenesis and in vitro deletions to be between 2.2 and 2.5 kb in the case of both E. coli genes and between 2.3 and 2.7 kb in the case of the mutant Bacillus gene. Restriction mapping indicated substantial sequence differences between the E. coli and B. megaterium penicillin acylase genes. Enzyme production in E. coli recombinants from both overproducing mutants was found to be constitutive and higher than in the original strains. The Bacillus penicillin acylase was produced intracellularly in E. coli recombinants, which is in contrast to the normal extracellular production of this enzyme in B. megaterium. Recombinant plasmids containing penicillin acylase genes from either source were found to be unstable in the absence of selection pressure for retention of the vector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00252550
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