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991.
Kasem K. Kasem Franklin A. Schultz 《Journal of Inorganic and Organometallic Polymers》1994,4(4):377-390
Multiply charged electroactive anions [IrCl
6
2–
, Fe(CN)
6
3–
, and W(CN)
8
4–
] are electrostatically incorporated in polymeric films of tris(4-vinyl-4-methyl-2,2-bipyridine) ruthenium(II) [poly-Ru(vbpy)
3
2+
] from aqueous trifluoroacetate solution. Values of apparent diffusion coefficients (D
ct) and heterogenous electron transfer rates (k
et) are measured for these anions as a function of their relative concentration (
M/
Ru) in the film.D
ct andk
et decrease systematically as
M/
Ru increases in a manner that is independent of charge and chemical identity of the ion. This result suggests that a nonchemical process, presumably electrostatic cross-linking, limits diffusional motion and is responsible for the decrease inD
ct andk
et with increasing anion content. Protonated polyvinyl-pyridine films exhibit similar ranges and variations inD
ct andk
et, which suggest similar structures and mechanisms of charge transport for these films and poly-Ru(vbpy)
3
2+
. 相似文献
992.
I. ledziska J. Sotysiak W. Staczyk 《Journal of Inorganic and Organometallic Polymers》1994,4(2):199-204
The synthesis and properties of individual liquid crystal oligo(cyclosiloxanes),, wherex=4–8 andR is a 4-methoxyphenyl-4-alkyloxybenzoate type of mesogenic group, is described. Preliminary results concerning the effect of ring size on the mesophase formation are included. X-ray diffraction studies have shown that the cyclosiloxanes form a smectic A1 phase. 相似文献
993.
Wolfgang Schwack Steven Nyanzi 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1994,198(1):3-7
The application of second-derivative UV-spectroscopy offers a highly sensitive and selective method for the determination of CS2 and COS, as acid hydrolysis products of dithiocarbamate und thiuram disulphide fungicides, using a methanolic amine absorption reagent (ethylenediamine, piperidine). With standard concentrations of 0.08–1.1 g CS2/ml and 0.3 to 2.0 g COS/ml, respectively, calibration curves with good correlation coefficients (r>0.999) were obtained. In comparison to the official method of the Deutsche Forschungsgemeinschaft (DFG method S15) the proposed alternative is at least 100 times more sensitive to CS2. Using the second derivative method it is possible not only to clearly differentiate between CS2 and COS but also to quantify both gases without resorting to tedious background corrections as compared to the direct photometric methods. Additionally, second derivative spectroscopy allows the direct determination of thiram in the concentration range 1–10 g/ml after its extraction with chloroform. For example, thiram in water (10 g/l) and in thiram/talc standards (10 mg/g) were determined with good precision (±2.0%).
Analytik der Dithiocarbamat-Fungicide. Bestimmung von CS2, COS sowie Thiram (TMTD) mittels Derivativ-UV-Spektroskopie
Zusammenfassung Die Anwendung der Derivativ-UV-Spektroskopie (2. Ableitung) erlaubt eine sehr empfindliche Bestimmung von CS2 und COS als Hydrolyseprodukte der Dithiocarbamat- und Thiuramdisulfid-Fungicide nach Absorption in einem methanolischem Amin-Reagens (Ethylendiamin, Piperidin). Mit Standard-Konzentrationen von 0,08–1,1 g CS2/ml bzw. 0,3–2,0 g COS/ml zeigten die Eichgeraden gute Korrelationskoeffizienten (r<0,999). Im Vergleich zur DFG-Methode S15 zeichnet sich die vorgeschlagene Alternative durch eine um zwei Zehnerpotenzen höhere Empfindlichkeit bei der CS2-Bestimmung aus. In der 2. Ableitung wird nicht nur die Unterscheidung von COS und CS2 eindeutig, sondern auch deren Quantifizierung ohne rechnerische Untergrundkorrekturen ermöglicht. Mit Hilfe der Derivativspektroskopie konnte außerdem Thiram (TMTD) in Konzentrationen von 1–10 g/ml direkt erfaßt werden. So ließen sich nach Extraktion mit Chloroform 10 g/L Thiram in Wasser mit einer Präzision von ±2,0% direkt bestimmen oder Thiram/Talkum-Standards (10 mg/g) überprüfen.相似文献
994.
Birefringence induced by thermal stress in bow-tie optical fibers is studied in detail by the use of the finite-element method. Results of computer modeling show that a higher degree of birefringence can be obtained with the use of a larger cladding and larger stress-applying zones in the fiber. 相似文献
995.
FTIR,DTA and XRD study of sphene (CaTiSiO5) crystallization in a ceramic frit and a non-borate base glass 总被引:1,自引:0,他引:1
The primary objective of this study has been the application of Fourier transform infrared (FTi.r.) absorption spectroscopy for both qualitative and quantitative characterization of sphene (CaTiSiO5) crystallization in test materials; namely, a CaO-TiO2-B2O3 bearing ceramic frit-S and a similar non-borate base glass-S. Differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscope/electron probe X-ray microanalysis (SEM/EPMA) techniques have also been used. FTi.r. absorption spectra have been shown to be capable of providing both qualitative and quantitative characterizations of crystal nucleation and growth in a frit-S and glass-S, being annealed between 800–1100° C. CaTiSiO5 appears as the dominant phase and-cristobalite as the transitional phase in frit-S; whereas, -CaSiO3 is dominant, CaTiSiO5 being a minor phase in the non-borate glass-S. As given by DTA data, the intense stage of crystal growth for frit-S is about 120–125° C lower than that of glass-S. B2O3 content and the relative amounts of CaO and TiO2 in the test specimens have been shown to give different modes of phase evolution and the onset temperature of nucleation. The activation energies,E
c, of crystal nucleation/growth was estimated by two different methods, namely, via DTA data and FTi.r. absorption spectra under the dominant surface nucleation mode for powder pellet specimens.E
c for CaTiSiO5, -CaSiO3 and-cristobalite in the frit-S and the non-borate base glass-S were estimated to be 219.6, 107.2 and 51.5 kJ mol–1, respectively, parallel to the decreasing order of chemical complexity of the glass-forming system. Similar quantitative FTi.r. studies in the determination ofE
c for a broader scope of glass compositions, and compared with that based on XRD and DTA data, are to be encouraged so that the application of FTi.r. spectroscopy in glass-ceramics may be advanced. 相似文献
996.
RADIOIMMUNOTOXICOLOGICALEFFECTOFENRICHEDURANIUMONCENTRALANDPERIPHERALIMMUNECELLSANDTHEPROTECTIVEACTIONOFIL-1ANDIL-2¥ZhuShoupe... 相似文献
997.
998.
G. Trigueros M. L. García C. Casas J. A. Ordóñez M. D. Selgas 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1995,201(3):298-302
Proteolytic and lipolytic activities of ninePenicillium strain and oneMucor strain previously isolated from Spanish dry fermented sausages have been studied.P. camemberti STCC 2267 andAspergillus oryzae ATCC 9362 were also used. Myofibrillar and sarcoplasmic proteins as well as fat extracted from pork meat and -naphthyl acetate, -naphthyl caprilate and -naphthyl laurate were used as substrates. Mould strains were grown in an enrichment medium prepared at pH 5.5 and 7.0 and malt extract broth. Strains were incubated at 18°C and 22°C. Myofibrillar proteins and -naphthyl caprilate were the most hydrolysed substrates. The greater enzymatic activities were observed at a pH 7.0 and 22°C. However, five mould strains showed considerable enzymatic activities under conditions similar to those used for ripening dry fermented sausages. These strains can be assayed as potential starter cultures for industrial sausage production. 相似文献
999.
Use of UV photography to identify aflatoxin-producing strains ofAspergillus flavus andA. parasiticus
Zdenka Cvetni Stjepan Pepeljnjak 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1995,201(4):399-401
UV photography in glucose, yeast extract (GY) agar medium was tested as a simple and rapid method for the distinction of afiatoxin-positive from aflatoxin-negative strains ofAspergillus flavus andA. parasiticus. In the UV photographs aflatoxin-producing moulds were identified as grey or black colonies, whereas aflatoxin-non-producing moulds appeared as white colonies. Of the afiatoxin-positive strains detected by the UV photographic method, 10% was confirmed by extraction of the GY agar medium and mould mycelium in chloroform, extracts which were analysed subsequently using thinlayer chromatography. Confirmation of aflatoxigenic strains was achieved by biosynthesis on liquid medium yeast extract sucrose (YES) broth. 相似文献
1000.
This paper describes an experimental computer program that applies the techniques of artificial intelligence to the creation of dance. Specifically, a user expresses a set of dance rules (in a special English-like rule language) which describes some of the dynamic aspects of a dance. These rules are applied nondeterministically by a rule driver program. The rules themselves are similar to those that form the knowledge base of expert systems. The rule driver embodies a heuristic algorithm of the type found in many artificial intelligence programs.James H. Bradford is an Associate Professor of Computer Science at Brock University. He is an active researcher in the area of Human/Computer Interaction with particular interests in the analysis of speech and the representation of dance.Paulette Côté-Laurence is an Associate Professor of Physical Education at Brock University. Her research interests are in the areas of motor control and the acquisition of dance skills, psychology of rhythm, and dance technology. 相似文献