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  • Ultrastructure  (52)
  • kinetics  (52)
  • healthy volunteers
  • Springer  (126)
  • 1995-1999  (59)
  • 1980-1984  (67)
  • 1955-1959
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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and Mechanism of the Thermal Decomposition of M(NO3)2·nH2O (M=Cu, Co, Ni) (1998)
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 617-623 
    Details
    ISSN: 1572-8943
    Keywords: kinetics ; nitrates ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper presents the results of simultaneous DTA-TG-DTG and DSC studies on the thermal decomposition of Cu(NO3)2·3H2O, Co(NO3)2·6H2O and Ni(NO3)2·6H2O in an air atmosphere. The mechanism and enthalpies of the investigated processes were determined, as well as the kinetic parameters of the processes run under non-isothermal conditions by means of Kissinger's method. The dependence of the activation energy on the ionic radius of the cations building up the crystal lattices of the investigated compounds was also studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010170231923
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics and Mechanism of the Natural Mineral Marmatite Oxidation Process (1998)
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 35-40 
    Details
    ISSN: 1572-8943
    Keywords: kinetics ; marmatite ; oxidation process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Results obtained by the comparative investigations of the natural mineral marmatite (Zn,Fe)S (Stari Trg, Yugoslavia) oxidation process are presented in this paper. Determination of the oxidation process mechanism was done by thermal analysis methods: DTA-TG-DTG and DSC, while Mössbauer spectroscopy, X-ray and electronic microanalysis were used for phase composition determination of the products formed during the oxidation process. Kinetics of the process was defined for two temperature intervals 862–973 and 1023–1173 K, under isothermal conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010196230637
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructure of the sperms ofPlumbago zeylanica (1981)
    Springer
    Protoplasma 107 (1981), S. 85-107 
    Details
    ISSN: 1615-6102
    Keywords: Male cytoplasmic inheritance ; Plumbago ; Pollen grain ; Pollen tube ; Sperm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Male gametes ofPlumbago zeylanica were examined in pollen grains and tubes using light and electron microscopy of chemically and physically fixed tissues, and Nomarski interference microscopy of isolated, living sperm cells. Male gametes are elongate, spindleshaped cells containing a nucleus, mitochondria, ER, ribosomes, vesicles, dictyosomes, probable microfilaments, and a variable number of plastids. In mature pollen grains ofP. zeylanica, the two sperm cells are directly linked; they share a transverse cell wall with plasmodesmata and are enclosed together by the inner vegetative cell plasma membrane. One of these two sperms is also associated with the vegetative nucleus as a consistent feature of pollen grain organization. The basis of this association appears to be a long, narrow projection of the sperm cell (averaging 〈 1 μm wide and about 30 μm long) which wraps around the periphery of the vegetative nucleus and occupies embayments of that nucleus. This association is maintained throughout pollen tube growth but becomes less extensive near the completion of tube growth and is severed following tube discharge. The consistent occurrence of the sperm-vegetative nucleus association in pollen grains, tubes and isolated pollen cytoplasm suggests that the two structures may be directly connected, but attempts to visualize this type of connection were unsuccessful. Possibly, the entwining nature and extent of complementary interfaces between vegetative nucleus and sperm may have a role in stabilizing their association. Functionally, the two sperms and vegetative nucleus appear to travel as a linked unit within the pollen tube, possibly increasing the effectiveness of gamete delivery and helping to ensure nearly simultaneous transmission of sperms into the receptive megagametophyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275610
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  • 4
    Electronic Resource
    Electronic Resource
    Frequency response analysis of a closed diffusion cell with two resonators (1996)
    Springer
    Adsorption 2 (1996), S. 265-277 
    Details
    ISSN: 1572-8757
    Keywords: frequency response ; diffusion cell ; kinetics ; diffusion ; heat effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This paper deals with frequency response (FR) analysis of a closed diffusion cell system with two resonators, that is both the LHS and RHS volumes are modulated. The analysis is made for a homogeneous particle described by a single effective diffusivity as well as a biporous pellet described by macropore and micropore diffusions. It is shown that if the perturbation of the volume of the reservoir #2 is lagged behind that of the reservoir #1 by 3π/2, the pressure response in reservoir #1 is significantly enhanced with larger amplitude as well as phase angle. When the perturbations of the two reservoirs are out of phase, the heat effect is reduced and can become insignificant when the two perturbations are completely out of phase (ψ = π). Under such a condition, the pressure difference between the two reservoirs could be doubled. In the case of biporous pellets, it is shown that the FR behaviours obtained for micropore diffusion control and macropore diffusion control are well distinguished. In the former case, the FR system reduces to a traditional batch adsorber one while in the latter case, the FR behaviour is the same as for a two resonator system with homogeneous particles. This difference can be used for the discrimination of micropore and macropore diffusion processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879541
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  • 5
    Electronic Resource
    Electronic Resource
    Equilibria and kinetics characterisation of two different structured nutshell-derived activated carbons (1997)
    Springer
    Adsorption 3 (1997), S. 267-275 
    Details
    ISSN: 1572-8757
    Keywords: characterisation ; equilibria ; kinetics ; micropore size distribution ; n-butane ; nutshell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Adsorption equilibria and dynamics ofn-butane on two activated carbon samples prepared from the physical activation of nutshell are studied in this paper. The micropore size distribution (MPSD) is considered as the main source of solid heterogeneity. Lennard-Jones' potential theory and Dubinin's theory (TVFM) are used in the equilibria data to derive the MPSD, which is well fitted by a Gamma distribution function. The adsorption energy distribution derived from the MPSD is very asymmetric for both the samples studied, and this energy distribution used in the HMSD/HMSMD kinetics models for the study of adsorption dynamics ofn-butane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01653629
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of alaproclate on antipyrine metabolite formation in man (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 447-452 
    Details
    ISSN: 1432-1041
    Keywords: alaproclate ; antipyrine clearance ; serotonin reuptake inhibitor ; healthy volunteers ; antipyrine metabolism ; metabolite clearance ; alaproclate kinetics ; inhibition of drug metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Alaproclate, a selective serotonin reuptake inhibitor, presently undergoing clinical trial for the treatment of major depressive disorders, has been shown to inhibit hexobarbital metabolism in mice. In the present study the influence of oral alaproclate on the total plasma clearance of antipyrine and on the formation of its metabolites was investigated in 10 healthy volunteers. The peak level of alaproclate was reached after about 1.5 h, and after a distribution phase, its plasma elimination half-life was between 3.0 and 3.5 h. Antipyrine tests were performed before treatment, during the first four doses and after the seventh dose of alaproclate 200 mg/day. During treatment, total plasma antipyrine clearance and the clearance for production of all antipyrine metabolites were reduced by 30%, indicating non-selective inhibition of oxidative drug-metabolizing enzyme activity in man by alaproclate. After the last dose of alaproclate, antipyrine plasma clearance and the clearance to its metabolites returned to control values. In order to allow more detailed evaluation of the results, the time course of the clearances for production of metabolites was investigated. This revealed that the extent of inhibition of metabolite formation by alaproclate was dependent on the plasma alaproclate level, indicating a rapidly reversible inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549593
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  • 7
    Electronic Resource
    Electronic Resource
    Studies of the different metabolic pathways of antipyrine in man (1982)
    Springer
    European journal of clinical pharmacology 21 (1982), S. 433-441 
    Details
    ISSN: 1432-1041
    Keywords: antipyrine ; antipyrine metabolites ; drug metabolism ; route of administration ; healthy volunteers ; urinary excretion ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of antipyrine in plasma and saliva, and urinary excretion of its major metabolites, were studied following i.v. and oral administration of antipyrine 500 mg to 6 healthy volunteers. Data from both plasma and saliva showed that the oral bioavailability of antipyrine given as an aqueous solution was complete. The saliva/plasma concentration ratio was constant with time from about 3 h onwards, with a mean value of 0.87 after oral and 0.91 after i.v. administration. It is concluded that the pharmacokinetic parameters of antipyrine can be satisfactorily established on the basis of salivary data, although the volume of distribution and clearance values are then slightly too high. After i.v. administration, 3.8±1.9% of the dose was excreted in urine as unchanged antipyrine in 48h, 24.9±6.3% as 4-hydroxyantipyrine, 16.5±3.2% as norantipyrine, 13.0±2.2% as 3-hydroxymethyl-antipyrine and 5.8±1.0% as 3-carboxy-antipyrine. No significant differences were observed following oral administration. The half-lives calculated from the linear part of the urinary excretion rate curves of the metabolites were about the same for oral and i.v. administration, and were of the same order of magnitude as the elimination half-life of parent drug in plasma and saliva. It is important for determination of the ultimate metabolite ratio that urine is collected for at least 36h, because there is a delay in the excretion of 3-hydroxymethyl-antipyrine in urine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542332
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructure of the cyanobacterium,Mastigocladus laminosus (1982)
    Springer
    Archives of microbiology 133 (1982), S. 11-19 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Ultrastructure ; Mastigocladus laminosus ; Fischerella ; True branching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphology and ultrastructure of the thermophilic cyanobacteriumMastigocladus laminosus were examined by scanning and transmission electron microscopy. Mature cultures consisted of relatively old, wide filaments that branched frequently to form younger, thinner filaments. The cells of the younger filaments had a consistently cylindrical morphology, while those of older filaments were rounded and pleomorphic. The internal ultrastructure of the cells depended somewhat on their age. As young cells became larger and wider, their thylakoids underwent slight rearrangement and spread out toward the center of the cytoplasm. Polyphosphate bodies, carboxysomes (polyhedral bodies), and lipid-body-like structures increased in number as the cells aged, but ribosomes and cyanophycin granules were depleted. Cell division involved septum formation followed by ingrowth of the outer membrane and sheath. Cells in older filaments were separated from each other by a complete layer of sheath material. Septum formation in older cells was also seen to occur parallel to the long axis of the filament, thereby confirming that true branching took place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00943762
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  • 9
    Electronic Resource
    Electronic Resource
    The effects of nitrogen limitation on the ultrastructure of the cyanobacterium Agmenellum quadruplicatum (1981)
    Springer
    Archives of microbiology 130 (1981), S. 204-212 
    Details
    ISSN: 1432-072X
    Keywords: Agmenellum quadruplicatum ; Nitrogen starvation ; Ultrastructure ; PATO poststain ; Cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nitrogen limitation on the ultrastructure of the unicellular cyanobacterium, Agmenellum quadruplicatum, were studied by thin sectioning transmission electron microscopy. Nitrogen became limiting for growth 14–15 h after transfer to nitrogen-limiting medium, but cultures retained full viability for at least 45 h. The c-phycocyanin: chlorophyll a ratio and cellular nitrogen content of the culture dropped rapidly after 14–15 h, as a progressive deterioration of major cell structures took place. Phycobilisomes were degraded first, followed by ribosomes and, then, thylakoid membranes. These structures were virtually depleted from the cells within 26 h. Intracellular polysaccharide accumulated in place of the normal cell structures throughout this period. Nitrogen limitation did not affect polyphosphate bodies, carboxysomes, lipid granules, the cell envelope, or the extra-cellular glycocalyx. All of the ultrastructural changes resulting from nitrogen limitation were reversed upon addition of nitrate to a starved culture. Most cell structures were restored within 3 h, and restoration was complete within 9 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00459520
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetics of the decomposition of calcium carbonate in the presence of Bi2O3 (1996)
    Springer
    Journal of thermal analysis and calorimetry 47 (1996), S. 569-575 
    Details
    ISSN: 1572-8943
    Keywords: Bi2O3 ; CaCO3 decomposition ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Former studies concerning the formation of the compounds in the pseudobinary systems of Bi2O3-MO type (M =Ca, Sr, Ca+Sr) have shown that the reaction which occurs with the highest rate is that between Bi2O3 and CaO. In the present work CaCO3 was used as CaO source. We carried out an investigation of the thermal decomposition of CaCO3 in the presence of Bi2O3 in comparison with the decomposition of pure CaCO3. The presence of Bi2O3 exerts a complex influence on the CaCO3 decomposition acting on the nucleation as well as on the diffusion of CO2. The decomposition of the samples with low Bi2O3 content follows the mechanism of a contracting sphere. A change from surface nucleation to bulk nucleation is recorded for higher amounts of Bi2O3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983998
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