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  • Springer  (69)
  • American Chemical Society (ACS)  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Inverse Problem of the Interval Linear System of Equations (1999)
    Springer
    Computing 63 (1999), S. 185-200 
    Details
    ISSN: 1436-5057
    Keywords: AMS Subject Classifications: ; Key words.Linear systems of equations, interval matrices, inequality constraints, constrained optimization.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract. Given a nonsingular central matrix $A_c$ , a central vector $b_c$ and a prescribed interval solution vector $x^I$ , it is required to find the maximum allowable deviation $\Delta A$ or $\Delta b$ so that the solution of the interval linear system $A^Ix = b^I$ is contained in $x^I$ . Special cases for $\Delta A$ and $\Delta b$ are considered and bounds on the entries of $A^I$ and $b^I$ are obtained either in a closed form, whenever possible, or via solving a specially designed constrained optimization problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006070050058
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  • 2
    Electronic Resource
    Electronic Resource
    Electrochemical study of the hetero-bimetallic complex [MeNC(CO)2Mn(dppm)2Pt(H)(CNMe)]+PF 6 − at a glassy carbon electrode (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 1075-1085 
    Details
    ISSN: 1434-4475
    Keywords: Cyclic voltammetry ; Convolution-deconvolution ; Chronopotentiometry ; Hetero-bimetallic complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Cyclische Voltammetrie (CV), Strom-Konvolution-Dekonvolution, Chronopotentiometrie und digitale Simulation wurden zur Bestimmung der kinetischen Parameter der Reaktion des hetero-bimetallischen Komplexes [MeNC(CO)2Mn(dppm)2Pt(H)(CNMe)]+PF 6 − an einer Glaskohlenstoffelektrode (GCE) in Dichlormethan eingesetzt. Der Komplex zeigt eine Reduktionsstufe bei −0.895±0.01 V und zwei anodische Stufen bei 0.903±0.01 V und 1.370±0.01 V. Auf die Reduktions-und Oxidationsschritte folgt unmittelbar ein schneller chemischer Prozeß. Aus den elektrochemischen Ergebnissen läßt sich ein Gesamtoxidationsprozeß nach einem EEC — Schema ableiten, während die Reduktion nach einem ECEC — Schema verläuft.
    Notes: Summary Cyclic voltammetry (CV), convolution-deconvolution transformation of current, chronopotentiometry (CP), and digital simulation studies were used to evaluate the kinetic parameters of the electrode reaction of the hetero-bimetallic complex [MeNC(CO)2Mn(dppm)2Pt(H)(CNMe)]+PF 6 − in dichloromethane at a glassy carbon electrode (GCE). It was found that the complex undergoes a reduction step at −0.895±0.01 V and two anodic steps at +0.903±0.01 V and 1.370±0.01 V. The reduction and oxidation steps are followed by a rapid chemical process. On the basis of the electrochemical results, an overall oxidation process was found to proceed as EEC, while the reduction process proceeds according to an ECEC scheme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811378
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  • 3
    Electronic Resource
    Electronic Resource
    Thermodynamic and voltammetric studies of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone (1995)
    Springer
    Monatshefte für Chemie 126 (1995), S. 851-862 
    Details
    ISSN: 1434-4475
    Keywords: Thermodynamics ; dc Polarography ; Cyclic voltammetry ; UV spectrophotometry ; Potentiometry ; Thiosemicarbazone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung UV-Spektroskopische, dc-polarographische, voltammetrische und coulometrische Messungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon (H2 SPT) inBritton-Robinson-Pufferlösungen (pH 2–12) wurden durchgeführt. Die spektrophotometrisch und potentiometrisch ermittelten Dissoziationskonstanten von H2 SPT in 5% (v/v)DMF/Wasser stimmen überein. In Lösungen mit einempH-Wert unter 8.5 zeigen die dc-Polarogramme eine einzelne diffusionskontrollierte polarographische Welle (4e−), während in Lösungen mit einempH-Wert von über 8.5 zwei Wellen zu beobachten sind. Die cyclischen Voltammogramme weisen in sauren und neutralen Lösungen einen, in basischen Lösungen hingegen zwei kathodische Peaks auf. Ein Elektrodenmechanismus wird vorgeschlagen und diskutiert. Der Effekt der Temperatur auf die Dissoziationskonstanten und die polarographischen Ergebnisse wurde ebenfalls untersucht. Die entsprechenden thermodynamischen Größen wurden bestimmt und werden diskutiert.
    Notes: Summary UV spectra, dc polarograms, cyclic voltammetry and coulometry measurements of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone (H2 SPT) were recorded inBritton-Robinson buffer solutions ofpH 2–12. The dissociation constants of H2 SPT evaluated spectrophotometrically and potentiometrically in a 5% (v/v)DMF-water mixture are concordant. The dc-polarograms in solutions ofpH〈8.5 exhibit a single 4-electron diffusion-controlled polarographic wave, whereas in solutions ofpH〉8.5 two waves are observed. The cyclic voltammograms give a single cathodic peak in acidic and neutral solutions, whereas two cathodic peaks can be identified in alkaline ones. An electrode mechanism is proposed and discussed. The effect of temperature on the dissociation constants and the polarographic data was also investigated; the corresponding thermodynamic parameters were derived and are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811004
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  • 4
    Electronic Resource
    Electronic Resource
    A Least-squares Approach to Shape Determination from Residual Self-potential Anomalies (1997)
    Springer
    Pure and applied geophysics 150 (1997), S. 121-128 
    Details
    ISSN: 1420-9136
    Keywords: Key words: SP interpretation, polarized structures, least-squares method.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —We have developed a least-squares minimization approach to determine the shape (shape-factor) of a buried polarized body from a residual self-potential anomaly profile. By defining the zero anomaly distance and the anomaly value at the origin on the profile, the problem of the shape-factor determination is transformed into the problem of finding a solution of a nonlinear equation of the form f(q) = 0. Procedures are also formulated to estimate the depth of polarization angle, and the electric dipole moment. The method is applied to synthetic data with and without random noise. The obtained shape-factor agrees very well with the model shape-factor when using synthetic data. After adding ± 2 percent random error in the synthetic data, the shape factor obtained is within ± 4 percent. Finally the validity of the method is tested on a field example from the Ergani copper district, Turkey.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050067
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  • 5
    Electronic Resource
    Electronic Resource
    Identification and Expression of the SOS Response, aidB-Like, Gene in the Marine Sponge Geodia cydonium: Implication for the Phylogenetic Relationships of Metazoan Acyl-CoA Dehydrogenases and Acyl-CoA Oxidases (1998)
    Springer
    Journal of molecular evolution 47 (1998), S. 343-352 
    Details
    ISSN: 1432-1432
    Keywords: Key words:Geodia cydonium— Sponges — SOS-response genetics — AidB — Acyl-CoA dehydrogenase — acyl-CoA oxidase — Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Sponges (Porifera) are the phylogenetically oldest metazoan organisms. From one member of the siliceous sponges, Geodia cydonium, the cDNA encoding a putative SOS protein, the AidB-like protein of the Ada system from bacteria, was isolated and characterized. The cDNA, GCaidB, comprises an open reading frame of 446 amino acid (aa) residues encoding a polypeptide with a calculated M r of 49,335. This molecule shows high similarity to the bacterial AidB proteins from Mycobacterium tuberculosis and Escherichia coli and somewhat lower similarities to acyl-CoA dehydrogenases (ADHs) and acyl-CoA oxidases (AOXs). Northern blot analysis confirmed the presence of the complete transcript. The deduced sponge aa sequence, GC_aidB, possesses the two characteristic acyl-CoA dehydrogenase signatures 1 and 2. Incubation of the sponge with N-methyl-N′-nitro-N-nitrosoguanidine causes a strong increase in the 2.1-kb large transcript of GCaidB; maximal expression is seen after 24 h of incubation with this DNA methylating agent. ADHs and AOXs can be grouped, depending on the position of the catalytically important Glu residue, into the Glu–Gly (Glu adjacent to Gly) class and the Glu–Arg (Glu adjacent to Arg) class. The phylogenetically oldest metazoan AidB-like molecule, GC_aidB of G. cydonium, belongs to the Glu–Gly class of ADHs. Phylogenetic analyses of the Glu–Gly class enzymes, with the described AidB-like protein from G. cydonium and the bacterial AidB polypeptides, together with metazoan ADHs and AOXs, revealed that the AidB(-like) proteins diverged first from a common ancestor, while the eukaryotic AOX and ADA polypeptides as well as the GHDs appeared later. According to the analyses, the very long-chain ADHs are older than the medium-chain, short-chain, and branched-chain ADHs. Inclusion of the phylogenetical oldest member of the Glu–Arg class of enzymes, the bacterial ADH–CaiA sequence in these analyses, revealed that this class of enzymes appeared later in evolution and arose from the Glu–Gly class perhaps after gene duplication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006392
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  • 6
    Electronic Resource
    Electronic Resource
    Induction of Hsp70 by the Herbicide Oxyfluorfen (Goal) in the Egyptian Nile Fish, Oreochromis niloticus (1999)
    Springer
    Archives of environmental contamination and toxicology 37 (1999), S. 78-84 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. This paper deals with the expression of the biomarker hsp70 in the liver and kidney of the freshwater fish Oreochromis niloticus following exposure to the herbicide oxyfluorfen (Goal). Fishes were exposed to three concentrations, the 96-h LC50 (3 mg/L), the 96-h ½LC50 (1.5 mg/L), and the 96-h ¼LC50 (0.75 mg/L) of oxyfluorfen for 6, 15, and 24 days, respectively, and samples were taken at three different time periods for each concentration. The livers responded to the herbicide by an induction of the expression of both the constitutive (hsp75; Mr 75 kDa) and the inducible (hsp73; Mr 73 kDa) hsp70 proteins. In kidney, the herbicide induced a time-dependent increase in the expression of the constitutive hsp70 (hsp75) as well, but the inducible hsp70 (hsp73) required much longer incubation periods to reach maximal levels (15 and 24 days). Our results suggest that expression of hsp70 in fish is a sensitive indicator of cellular responses to herbicide exposure in the aquatic environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900492
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  • 7
    Electronic Resource
    Electronic Resource
    Simultaneous determination of Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe in water samples by differential pulse stripping voltammetry at a hanging mercury drop electrode (2000)
    Springer
    Fresenius' journal of analytical chemistry 367 (2000), S. 378-383 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A highly sensitive and selective voltammetric procedure is described for the simultaneous determination of eleven elements (Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe) in water samples. Firstly, differential pulse anodic stripping voltammetry (DPASV) with a hanging mercury drop electrode (HMDE) is used for the direct simultaneous determination of Cd, Pb, Cu, Sb and Bi in 0.1 M HCl solution (pH = 1) containing 2 M NaCl. Then, differential pulse cathodic stripping voltammetry (DPCSV) is used for the determination of Se in the same solution. Zn is subsequently determined by DPASV after raising the pH of the same solution to pH 4. Next, the pH of the medium is raised to pH 8.5 by adding NH3/NH4Cl buffer solution for the determination of Mn by DPASV. Ni and Co are determined in the same solution by differential pulse adsorptive stripping voltammetry (DPAdSV) after adding DMG (1 × 10–4 M). Finally, 1 × 10–5 M 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is added to the solution for the determination of Fe by DPAdSV. The optimal conditions are described. Relative standard deviations and relative errors are calculated for the eleven elements at three different concentration levels. The lower detection limits for the investigated elements range from 1.11 × 10–10 to 1.05 × 10–9 M, depending on the element determined. The proposed analysis scheme was applied for the determination of these eleven elements in some ground water samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160000410
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  • 8
    Electronic Resource
    Electronic Resource
    Induction of DNA Strand Breaks and Expression of HSP70 and GRP78 Homolog by Cadmium in the Marine Sponge Suberites domuncula (1999)
    Springer
    Archives of environmental contamination and toxicology 36 (1999), S. 47-55 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The marine sponge Suberites domuncula was used as a bioindicator to study the effects of cadmium on the occurrence of DNA strand breakage and on the induction of the expression of the stress biomarkers, heat shock protein 70 (HSP70) and glucose-regulated protein 78 (GRP78) homolog. The cDNA encoding GRP78 homolog from S. domuncula was isolated and characterized. The GRP78 cDNA has a length of 2.1 kb and displays characteristic features of the HSP70 family; it encodes an aa sequence of Mr 72,000. Exposure of S. domuncula to 1 mg/L of cadmium chloride for 24 h caused a strong (16.6-fold) increase in cadmium content to 7.7 μg/g wet weight of sponge tissue; after an incubation period of 6 days, the accumulation was 20.4-fold. The increase in cadmium content was paralleled by a transient decrease in zinc content at days 1 and 3. Exposure of S. domuncula to cadmium chloride also resulted in a marked increase in the number of DNA single strand breaks, as assessed by a recently developed fast and sensitive microplate assay. The maximum increase in DNA damage was observed after an incubation of 12 h in the presence of 1 mg/L of cadmium chloride; after longer incubation, the number of damaged sites decreased, most likely due to DNA repair. Quantitative analysis of the expression of HSP70 (Mr 73 kDa) revealed that onset of maximal levels of HSP70 depends on the concentration of cadmium chloride in the ambient seawater. Maximal induction (8.9-fold increase compared to control) of HSP70 following exposure to 1 mg/L of cadmium chloride was found after 12 h, while longer incubation periods (3–6 days) were needed to reach maximum levels of HSP70 in the presence of lower concentrations of cadmium chloride (0.1 mg/L and 0.01 mg/L). Northern blot analysis revealed that the level of the 2.0 kb sponge GRP78 homolog mRNA transiently increased under cadmium stress; the maximum increase in the presence of 0.1 mg/L of cadmium chloride was observed at day 3. Our results suggest that sponges are useful indicator organisms to assess the genotoxic risks of cadmium pollution in marine environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002449900441
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  • 9
    Electronic Resource
    Electronic Resource
    17β-Estradiol-dependent regulation of chaperone expression and telomerase activity in the marine sponge Geodia cydonium (1999)
    Springer
    Marine biology 133 (1999), S. 1-10 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is known that species belonging to the lowest metazoan phylum, the Porifera (sponges), do not develop tumors. Sponge cells share with tumor cells of higher animals at least one characteristic; they contain high levels of telomerase activity, suggesting that they possess a high proliferation capacity. This assumption, however, has not been substantiated experimentally. In addition, sponges show a specific bauplan, leading us to postulate that they undergo apoptosis to replace a given set of cells at a given time. In the present study, 17β-estradiol (βE2) was used as a defined agent to assess its effect on both the telomerase activity and the process of apoptosis in the marine sponge Geodia cydonium (Jameson). It was found that βE2 (100 to 500 ng ml−1) caused increased expression (i) of the heat-shock protein HSP70 (Mr=70 000), a cytoplasmic chaperone; and (ii) of the nuclear chaperone thioredoxin (TRX), a protein involved in the control of cancer cell growth. For this purpose the gene of G. cydonium encoding TRX was cloned, and the cDNA was applied for the determination of the expression. Verapamil, an inhibitor of both the mammalian multidrug resistance pump and the invertebrate multixenobiotic resistance pump, was used in co-incubation experiments with βE2 to increase the uptake of βE2. The experiments revealed that verapamil augmented the βE2 effect on the expression of the two chaperones, HSP70 and TRX. In addition, the tissue of G. cydonium underwent apoptosis, and the cells lost their telomerase activity. In parallel with the induction of the apoptotic process, the number of DNA strand breaks increased. It is concluded that βE2 displays its effect via the production of reactive oxygen species (ROS). At physiological concentrations ROS cause the expression of HSP70 and TRX, while at higher ROS levels, generated during the co-incubation period of βE2 with verapamil, the cells undergo apoptosis and lose telomerase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050436
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  • 10
    Electronic Resource
    Electronic Resource
    Survey of the parasitoids of the Greasy Cutworm,Agrotis ipsilon Rott. (Lepidoptera, Noctuidae) in Egypt (1987)
    Springer
    Journal of pest science 60 (1987), S. 155-157 
    Details
    ISSN: 1612-4766
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Zusammenfassung Wöchentliche Aufsammlungen der Raupen vonA. ipsilon während der Jahre 1983/84 bis 1985/86 im mittleren Ägypten erbrachten zwei gregäre Endoparasitoiden,Apanteles ruficrus Hal. undMeteorus rubens Nees. (beide Hym., Braconidae). Sie erreichen zusammen in den 3 Jahren 20,2, 22,2 und 24,7%, i.M. 22,5% (A. ruficrus=10,3%, undM. rubens=12,2%). Die höchsten Parasitierungsraten wurden im März und April festgestellt.
    Notes: Abstract Weekly samples of the cutworm,Agrotis ipsilon Rott. larvae were collected for 3 successive season 1983/84–1985/86 from 3 Governorates in middle Egypt to survey and evaluate the role of parasitoids in suppressing the pest population. Two gregarious internal larval parasitoids were recorded,Apanteles ruficrus Hal. andMeteorus rubens Nees. (Hymenoptera, Braconidae). Percentages of parasitism were estimated. They reached 20.2, 22.2 and 24.7% in seasons 1983/84, 1984/85 and 1985/86, respectively, with an average of 22.5% (10.3%A. ruficrus and 12.2%M. rubens). The highest rates of parasitism were recorded in March and April.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01907546
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