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  • 1
    Electronic Resource
    Electronic Resource
    The role of bromine and chlorine chemistry for arctic ozone depletion events in Ny-Ålesund and comparison with model calculations (1999)
    Springer
    Annales geophysicae 17 (1999), S. 941-956 
    Details
    ISSN: 0992-7689
    Keywords: Atmospheric composition and structure (troposphere - composition and chemistry; instruments and techniques)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract During the Arctic Tropospheric Ozone Chemistry (ARCTOC) campaigns at Ny-Ålesund, Spitsbergen, the role of halogens in the depletion of boundary layer ozone was investigated. In spring 1995 and 1996 up to 30 ppt bromine monoxide were found whenever ozone decreased from normal levels of about 40 ppb. Those main trace gases and others were specifically followed in the UV-VIS spectral region by differential optical absorption spectroscopy (DOAS) along light paths running between 20 and 475 m a.s.l. The daily variation of peroxy radicals closely followed the ozone photolysis rate J(O3(O1D)) in the absence of ozone depletion most of the time. However, during low ozone events this close correlation was no longer found because the measurement of radicals by chemical amplification (CA) turned out to be sensitive to peroxy radicals and ClOx. Large CA signals at night can sometimes definitely be assigned to ClOx and reached up to 2 ppt. Total bromine and iodine were both stripped quantitatively from air by active charcoal traps and measured after neutron activation of the samples. Total bromine increased from background levels of about 15 ppt to a maximum of 90 ppt during an event of complete ozone depletion. For the spring season a strong source of bromine is identified in the pack ice region according to back trajectories. Though biogenic emission sources cannot be completely ruled out, a primary activation of halogenides by various oxidants seems to initiate an efficient autocatalytic process, mainly driven by ozone and light, on ice and perhaps on aerosols. Halogenides residing on pack ice surfaces are continuously oxidised by hypohalogenous acids releasing bromine and chlorine into the air. During transport and especially above open water this air mixes with upper layer pristine air. As large quantities of bromine, often in the form of BrO, have been observed at polar sunrise also around Antarctica, its release seems to be a natural phenomenon. The source strength of bromine from halogen activation on the pack ice, as based on the measured inorganic bromine levels, averages about 1012 Br-atoms m−2 s−1 during sunlit periods in Arctic spring. The total source strength of inorganic bromine from sunlit polar regions may therefore amount to 30 kt y−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-0941-4
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Skeletal Site of Origin and Donor Age on Osteoblastic Cell Growth and Differentiation (1999)
    Springer
    Calcified tissue international 64 (1999), S. 280-286 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Human osteoblastic cells — Skeletal site — Aging.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Bone loss with aging may be due, at least in part, to inadequate bone formation. Moreover, the process of bone aging is known to follow a different pattern throughout the skeleton. In this study, we examined the cell proliferation rate (area under the cell growth curve, AUC) and the secretion of C-terminal type I procollagen (PICP), alkaline phosphatase (ALP), and osteocalcin (OC) in primary cultures of osteoblastic cells from human trabecular bone. Osteoblastic cells were obtained for 168 donors (100 women and 68 men). Ninety-eight bone samples were obtained from subjects undergoing knee arthroplastia, 52 aged 50–70 years (64 ± 5) and 46 over age 70 (73 ± 2). Another 70 bone samples were obtained from subjects undergoing hip arthroplastia; 51 were 50–70 years old (64 ± 4) and 19 were over 70 (75 ± 5). Osteoblastic cells from the older donors had a lower proliferation rate and OC secretion than those from younger subjects. However, ALP secretion was higher in the former subjects, whereas PICP secretion was unchanged. Osteoblastic cells from hip had a lower proliferation rate than those from knee. PICP secretion was also lower and ALP secretion was higher in the former cells. In age-matched cell cultures, osteoblastic cells from the knee had higher proliferation rate and PICP secretion than osteoblastic cells from the hip. However, ALP secretion was lower in knee osteoblastic cells than those from hip only in the younger group. With aging, ALP secretion was found to increase in knee osteoblactic cells, whereas OC secretion decreased in osteoblastic cell cultures from the hip. Our findings suggest that bone loss with aging may be accounted for, at least in part, by a decreased osteoblastic cell proliferation and an increased osteoblastic maturation. In addition, our data indicate that these changes with aging do not occur similarly at different skeletal sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900619
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  • 3
    Electronic Resource
    Electronic Resource
    Lack of Relationship Between BsmI Vitamin D Receptor Polymorphism and Primary Hyperparathyroidism in a Spanish Female Population (1999)
    Springer
    Calcified tissue international 65 (1999), S. 214-216 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Hyperparathyroidism — VDR polymorphism — Parathyroid adenoma.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The role of vitamin D receptor (VDR) gene polymorphisms in the pathogenesis of hyperparathyroidism is uncertain. Controversial results have been reported. The aim of this study was to explore the relevance of BsmI VDR gene polymorphism in patients with primary hyperparathyroidism (PHPT) due to adenomas. For this purpose, 36 postmenopausal patients with PHPT, mean age 64 years, were compared with a normal age-matched female population (n = 81). BsmI polymorphism distribution in PHPT group was as follows: Bb 50% (18/36); BB 22% (8/36); bb 28% (10/36). In the control group, the distribution was Bb 49% (40/81); BB 16% (13/81); bb 35% (28/81). No statistical differences were found between the two groups. In the PHPT group, no statistical associations were found between different allelic distribution and age, creatinine, hematocrit, phosphorus, alkaline phosphatase (ALP), total calcium, serum parathyroid hormone (PTH), or gland weight. By contrast, levels of serum calcium and iPTH values positively correlated with the PT weight (r = 0.421 and 0.599, respectively, P= 0.0001). Our data suggest that at least in this group, BsmI VDR gene polymorphism appears to be of minor relevance in clinical presentation and possibly, tumorigenesis in PHPT due to adenomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900685
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  • 4
    Electronic Resource
    Electronic Resource
    Somatic embryogenesis from stem and leaf explants of Quercus robur L. (1999)
    Springer
    Plant cell reports 18 (1999), S. 538-543 
    Details
    ISSN: 1432-203X
    Keywords: Key words Oak ; Quercus robur ; Secondary embryogenesis ; Somatic embryo induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Internodal and leaf segments from pedunculate oak (Quercus robur L.) seedlings were used as explant source to induce somatic embryogenesis. Auxin treatment influenced embryogenic response, which only occurred in explants initially cultured on media containing 4 mg/l naphthaleneacetic acid (NAA) and different benzyladenine (BA) concentrations. After 6 weeks of culture on induction medium, the explants were transferred to medium supplemented with 0.1 mg/l BA and 0.1 mg/l NAA, and 4 weeks later, they were subcultured in a growth-regulator-free medium, in which somatic embryos arose through indirect regeneration on the surface of a nodular callus. Somatic embryos were induced in explants of two out of four seedling provenances. The induction frequency ranged from 16% in leaf explants to 4% in internodal explants. Somatic embryos developed two cotyledons, which were translucent or opaque-white in appearance, but anomalous morphologies were also observed. Different embryogenic lines were established and maintained by repetitive embryogenesis in multiplication medium containing 0.1 mg/l BA plus 0.05 mg/l NAA. These results indicate that tissues from explants other than Q. robur zygotic embryos are able to produce embryogenic cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050618
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  • 5
    Electronic Resource
    Electronic Resource
    Marine Bacteria Tolerant to Chlorophenols (1999)
    Springer
    Bulletin of environmental contamination and toxicology 62 (1999), S. 272-277 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001289900870
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  • 6
    Electronic Resource
    Electronic Resource
    Thermogravimetric Analysis for Acidity Determination in Pillared Clays (1999)
    Springer
    Journal of thermal analysis and calorimetry 55 (1999), S. 461-466 
    Details
    ISSN: 1572-8943
    Keywords: pillared clays ; surface acidity measurements ; TG analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermogravimetric analysis of pyridine adsorption was applied to study the acidity at different temperatures of clays pillared with Al pillars and mixed Al-Ga pillars, in relation to the starting montmorillonite. These results were compared with those obtained by means of a pulse-chromatographic technique. The pillaring process produces a large number of acid centers in the samples. Al-Ga-PILC has a higher acidity than Al-PILC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010167602247
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  • 7
    Electronic Resource
    Electronic Resource
    Responses of dune mosses to experimental burial by sand under natural and greenhouse conditions (1999)
    Springer
    Plant ecology 145 (1999), S. 209-219 
    Details
    ISSN: 1573-5052
    Keywords: Bryophytes; Burial tolerance; Emergence; Sand dunes; Tolerance index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sand movement is a predominant feature of mobile coastal and lake-shoreline sand dunes. Plants growing in these environments are able to withstand and survive periods of burial by sand. Although mosses are important dune stabilizers in temperate dunes, there are few studies focused on their response to burial by sand. In this study we examined the effects of burial by sand on 11 moss species that grow naturally on Lake Huron sand dunes and occur in a gradient of habitats from the foredunes along the shore to forested areas. Artificial burial treatments (sand depth of 0, 1, 3, 5 and 7 cm) were imposed under greenhouse and field conditions. We measured final plant cover and calculated the speed of emergence and an interpretive index (tolerance index) to compare burial responses among species by calculating a burial ratio which standardized the initial size of each species. In the greenhouse, Ceratodon purpureus and Ditrichum flexicaule recorded the highest mean speeds of emergence and Dicranum scoparium, Plagiothecium laetum, Dicranum flagellare and Brachythecium sp. 1 the lowest. In the field the trends were similar although the speed of emergence was much slower. Three types of response to burial were evident in plant cover: neutral, inhibition and stimulation. Although all eleven studied species were able to emerge from the different depths of burial, we observed that species colonizing areas with high sand mobility and deposition (C. purpureus and D. flexicaule) were the most tolerant and emerged from depths of up to 35 times their height. Species growing inland, at the base of trees (Dicranum scoparium, Brachythecium sp. 2, Plagiomnium cuspidatum and Dicranum flagellare) showed the least tolerance of burial.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009850304137
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  • 8
    Electronic Resource
    Electronic Resource
    Temporal changes in tissue metabolic capacities of wild Atlantic cod Gadus morhua (L.), from Newfoundland (1999)
    Springer
    Fish physiology and biochemistry 20 (1999), S. 181-191 
    Details
    ISSN: 1573-5168
    Keywords: fish ; white muscle ; aerobic metabolism ; anaerobic metabolism ; growth rate ; seasons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used biochemical indicators to assess the physiological status of Atlantic cod (Gadus morhua) sampled at different sites and times along the Newfoundland coast. The physiological status of cod changed more with time of sampling and size of the cod than with the site of sampling. The levels of muscle glycolytic enzymes and proteins suggest that cod from both near shore and offshore environments experienced the most favorable conditions in late summer and early fall. In small cod sampled near shore, increases in muscle aerobic capacity and protein contents accompanied the decrease in temperature from September to December. The positive allometry of muscle glycolytic capacities was more apparent in samples obtained in early winter than at other times, suggesting that the energetic status of cod affects the expression of this allometric relationship. On the other hand, a negative allometry of muscle aerobic capacities was apparent throughout the study. Reproductive maturity had few effects upon the biochemical parameters measured and tended to favor mature over immature cod. Our results suggest that cod in these areas were only growing in fall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007747600759
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  • 9
    Electronic Resource
    Electronic Resource
    Morphological development and gibberellin production by different strains of Gibberella fujikuroi in shake flasks and bioreactor (1999)
    Springer
    World journal of microbiology and biotechnology 15 (1999), S. 753-755 
    Details
    ISSN: 1573-0972
    Keywords: Conidia ; cultures ; fermentation ; G. fujikuroi ; morphological ; strains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Strain H-984 of G. fujikuroi grown for 38 h in a shake flask with medium containing 20 g glucose l−1, 3 g yeast extract l−1, 2.5 g NH4NO3 l−1, 0.5 g KH2PO4 l−1, 0.1 g MgSO4 l−1, 1 g CaCO3 l−1, and inoculated into a bioreactor with medium containing 60 g glucose l−1; 1 g NH4Cl l−1; 3 g KH2PO4 l−1 and 1.5 g MgSO4 l−1 produced 1100 mg gibberellic acid l−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008976000179
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  • 10
    Electronic Resource
    Electronic Resource
    Estimates of Barometric Pumping of Moisture Through Unsaturated Fractured Rock (1999)
    Springer
    Transport in porous media 36 (1999), S. 85-119 
    Details
    ISSN: 1573-1634
    Keywords: barometric pumping ; two-phase flow ; fractured rock.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract We present a theory for the motion of water vapor at depth in a discretely fractured permeable medium induced by atmospheric barometric pressure fluctuations, or ‘barometric pumping’. The theory involves multiphase mass and energy transport in a fracture/matrix system, with discrete representation of the fracture system. The barometric pressure fluctuations are approximated as periodic in time, with amplitude corresponding to measured values. To simplify the analysis, a ‘single-horizon’ approximation is applied in which the time-mean gradient is used to evaluate the vertical advective flux in the fractures. Time-periodic solutions are obtained numerically, enabling the calculation of the net efflux of moisture per cycle. The model is applied to material representative of the Yucca Mountain region of southwestern Nevada. The results indicate that the efflux of moisture carried upward from significant depths by barometric pumping is much less than the near surface efflux that is commonly estimated by assuming that air enters the medium dry and is returned to the atmosphere fully saturated with water vapor. This near surface efflux consists primarily of moisture discharged from the upper layer which is frequently replenished by precipitation. Of greater interest to nuclear waste repository design and estimations of net infiltration in arid regions is the fraction of the total moisture efflux that comes from significant depths. This deep transport is quantified by the fracture/matrix transport model described here. Although the transport by barometric pumping from depth is small compared to the total moisture expelled from the surface layer, it is an order of magnitude greater than the vertical moisture flux carried from depth by diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006593628835
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