| 21. |
- Kirilin, A, et al.
(author)
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Mechanistic investigations of the reaction network in chemobiocatalyzed synthesis of R1Phenylethyl Acetate
- 2010
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In: Kinetics and catalysis. - : Springer. - 0023-1584 .- 1608-3210. ; 51:6, s. 809-815
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Journal article (peer-reviewed)abstract
- The kinetics and reaction network of the onepot synthesis of R1phenylethyl acetate was investigated at 70°C in toluene over a combination of three different catalysts: PdZn/Al2O3 as a catalyst for acetophenone hydrogenation, lipase as an enzymatic catalyst for R1phenylethanol acylation with ethyl acetate and Ru/Al2O3 as a racemization catalyst for S1phenylethanol. In addition to the desired reactions, other reactions, namely hydrogenolysis and dehydration of (R, S)1phenylethanol and debenzylation of (R, S)1phenylethyl acetate also occurred. The kinetic results revealed that ethylbenzene formation was enhancedwith higher amounts of PdZn/Al2O3, whereas lipase did not catalyze ethylbenzene formation. Furthermore, ethylbenzene was formed in the hydrogenolysis of (R, S)phenylethanol and in the debenzylation of (R, S)1phenylethylacetate over Pd/Al2O3 catalyst. The presence of Ru/Al2O3 catalyst, in which Ru was in the oxidation state of 3+, enhanced the formation of R1phenylethyl acetate, although no clear racemization of S1phenylethanol during the onepot synthesis of R1phenylethyl acetate was observed. Dynamic kinetic resolution of (R, S)1phenylethanol in toluene, was, however, demonstrated over Ru/Al2O3 and lipase.
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| 22. |
- Kochur, A.G., et al.
(author)
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Mn3s X-ray photoelectron spectra of polynuclear trimethylacetate complexes of manganese
- 2010
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In: Bulletin of the Russian Academy of Sciences: Physics. - : Allerton Press. - 1062-8738. ; 74:5, s. 625-630
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Journal article (peer-reviewed)abstract
- The Mn3s X-ray photoelectron spectra of manganese atoms in mono-, bi-, tri-, and hexanuclear trimethylacetate Mn complexes and MnIICl 2, MnIIIOOH, MnIVO2. ionic compounds were measured. The 3s spectra of the manganese atoms in MnII, MnIII, and MnIV valent states were calculated within the isolatedion approximation. The relationship between the characteristics of the Mn3s spectra and the magnetic moments of the manganese ions in the complexes is discussed.
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| 23. |
- Kochur, A. G., et al.
(author)
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Study of the electronic structure of polynuclear cobalt trimethylacetate complexes by Co3s and Co3p X-ray photoelectron spectroscopy
- 2011
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In: Russian Journal of Inorganic Chemistry. - 0036-0236 .- 1531-8613. ; 56:3, s. 402-408
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Journal article (peer-reviewed)abstract
- The electronic structure of mono-, hexa-, and nonanuclear cobalt trimethylacetate complexes was studied by XPS. The Co3s- and Co3p X-ray photoelectron spectra of the complexes were recorded. The Co3p spectrum of bivalent cobalt was calculated in the isolated-ion intermediate-coupling approximation. Spectrum analysis showed that the [Co(N-Phobsqdi)2(eta'-N-Ph-opda)(OOCCMe(3))] complex is a strong-field complex with Co(III) in the diamagnetic state; the [Co(dipy)(2)(OOCCMe(3))(2)], [Co(dipyam)(OOCCMe(3))(2)], and [Co(9)(mu(3)-OH)(6)(mu-OOCCMe(3))(12)(OCMe(2))(4)] are high-spin weak-field Co(II) complexes; and the [Co(6)(mu(4)-O)(2)(OOCCMe(3))(10)(THF)(4)] complex contains both the Co(II) and Co(III) atoms. The energy position of major Co3s- and Co3p spectral maxima were found to be sensitive to the nature of the nearest environment of cobalt atoms. The data correlate well with X-ray crystallographic data.
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| 24. |
- Kochur, A. G., et al.
(author)
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X-ray photoelectron Fe3s and Fe3p spectra of polynuclear trimethylacetate iron complexes
- 2010
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In: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 180:1-3, s. 21-26
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Journal article (peer-reviewed)abstract
- X-ray photoelectron Fe3s and Fe3p spectra are employed to study the electron structure and the spin magnetic state of bi-, tri-, and hexa-nuclear trimethylacetate iron complexes. Assignment of the spectra is performed based on an isolated-ion Pauli-Fock calculation of Fe3s and Fe3p spectra of the Fe atoms in bi- and tri-valent states. Nonequivalent Fe(III) and Fe(II) atoms are detected in tri- and hexa-nuclear complexes. Paramagnetic-limit molecular magnetic moments are calculated using effective atomic magnetic moments obtained from spin-sensitive spectral characteristics. Comparison of those values with the magnetic measurements data demonstrates antiferromagnetic interaction within the complexes.
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| 25. |
- Kononova, S V, et al.
(author)
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Phase-inversion gradient-porous films on the basis of polyamidoimides derived from phthalimidobenzenedicarbonyl dichloride and various diamines
- 2010
-
In: Russian journal of general chemistry. - : SpringerLink. - 1070-3632 .- 1608-3350. ; 80:10, s. 1977-1985
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Journal article (peer-reviewed)abstract
- Morphology of microporous films prepared from aromatic polyamidoimides under different molding conditions was studied by scanning, transmission, and atomic force microscopy with the specific attention given to the nanosize skin layer. The films were manufactured by the phase inversion molding of aromatic polyamidoimides which were synthesized by low-temperature polycondensation of phthalimidobenzenedicarbonyl dichloride with various diamines. Comparison of the parameters of films, including their wettability and X-ray photoelectron spectroscopy data, gave additional information on factors affecting the mechanism of formation of microporous membranes in the system polymer (polyamidoimide)-solvent (N-methylpyrrolidin-2-one)-non-solvent (water).
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| 26. |
- Kozin, Philipp A, et al.
(author)
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Electrolyte Ion Binding at Iron Oxyhydroxide Mineral Surfaces
- 2013
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 29:39, s. 12129-12137
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Journal article (peer-reviewed)abstract
- Electrolyte ion loadings at the surfaces of synthetic goethite (α-FeOOH) and lepidocrocite (γ-FeOOH) particles that were pre-equilibrated in aqueous solutions of 10 mM NaCl and NaClO4 at 25 °C were investigated by cryogenic X-ray photoelectron spectroscopy (XPS). Atomic concentrations of Cl(-), ClO4(-), and Na(+) were correlated to potential determining ion (pdi; H(+), OH(-)) loadings obtained by potentiometric titrations. While Cl(-) promoted more pdi adsorption than ClO4(-), due to its greater charge-to-size ratio, both ions followed the same loading dependence on pdi adsorption, in contrast to previous studies supporting the concept for negligible perchlorate adorption. Lepidocrocite particles exhibited a stronger response of electrolyte adsorption to pdi loadings due electrolyte ion adsorption on the proton inactive (010) plane. These particles also acquired greater sodium loadings than goethite. These loadings were moreover considerably enhanced by perchlorate adsorption, possibly due to a thickening of the interfacial region in NaClO4 on the (010) plane. Finally, goethite particles with rougher surfaces acquired greater pdi and ion loadings than on those with smoother surfaces. No strong differences could be discerned between Cl(-) and ClO4(-) loadings on these materials. This work thus identified key aspects underpinning the relationship between pdi and electrolyte loadings at FeOOH mineral surfaces of environmental and technological importance.
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| 27. |
- Kukkola, Jarmo, et al.
(author)
-
Electrical transport through single-wall carbon nanotube-anodic aluminum oxide-aluminum heterostructures
- 2010
-
In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 21:3, s. 35707-
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Journal article (peer-reviewed)abstract
- Aluminum foils were anodized in sulfuric acid solution to form thick porous anodic aluminum oxide (AAO) films of thickness approximately 6 microm. Electrodes of carboxyl-functionalized single-wall carbon nanotube (SWCNT) thin films were inkjet printed on the anodic oxide layer and the electrical characteristics of the as-obtained SWCNT-AAO-Al structures were studied. Nonlinear current-voltage transport and strong temperature dependence of conduction through the structure was measured. The microstructure and chemical composition of the anodic oxide layer was analyzed using transmission and scanning electron microscopy as well as x-ray photoelectron spectroscopy. Schottky emission at the SWCNT-AAO and AAO-Al interfaces allowed by impurity states in the anodic aluminum oxide film together with ionic surface conduction on the pore walls of AAO gives a reasonable explanation for the measured electrical conduction. Calcined AAO is proposed as a dielectric material for SWCNT-field effect transistors.
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| 28. |
- Kukkola, Jarmo, et al.
(author)
-
Gas sensors based on anodic tungsten oxide
- 2011
-
In: Sensors and actuators. B, Chemical. - : Elsevier B V. - 0925-4005 .- 1873-3077. ; 153:2, s. 293-300
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Journal article (peer-reviewed)abstract
- Nanostructured porous tungsten oxide materials were synthesized by the means of electrochemical etching (anodization) of tungsten foils in aqueous NaF electrolyte. Formation of the sub-micrometer size mesoporous particles has been achieved by infiltrating the pores with water. The obtained colloidal anodic tungsten oxide dispersions have been used to fabricate resistive WO3 gas sensors by drop casting the sub-micrometer size mesoporous particles between Pt electrodes on Si/SiO2 substrate followed by calcination at 400 °C in air for 2 h. The synthesized WO3 films show slightly nonlinear current–voltage characteristics with strong thermally activated carrier transport behavior measured at temperatures between −20 °C and 280 °C. Gas response measurements carried out in CO, H2, NO and O2 analytes (concentration from 1 to 640 ppm) in air as well as in Ar buffers (O2 only in Ar) exhibited a rapid change of sensor conductance for each gas and showed pronounced response towards H2 and NO in Ar and air, respectively. The response of the sensors was dependent on temperature and yielded highest values between 170 °C and 220 °C.
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| 29. |
- Kukkola, Jarmo, et al.
(author)
-
Inkjet-printed gas sensors : metal decorated WO3 nanoparticles and their gas sensing properties
- 2012
-
In: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 22:34, s. 17878-17886
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Journal article (peer-reviewed)abstract
- Inkjet deposition is an attractive technology to localize nanomaterials in an area-selective manner on virtually any kind of surfaces. Great advantages of the method are effective usage of materials, low processing temperatures and few required manufacturing steps, thus enabling rapid prototyping and bulk production with reasonably low cost. A number of different electrical devices such as light emitting diodes, transistors and solar cells have already been demonstrated, reflecting the versatility of inkjet printing. In this paper, we collect the contemporary results on inkjet deposited gas sensors and show examples of such gas sensing devices based on surface modified WO3 nanoparticles for efficient discrimination of various gaseous analytes from sub-ppm up to nearly 0.1% concentration levels in air.
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| 30. |
- Kukkola, J, et al.
(author)
-
Novel printed nanostructured gas sensors
- 2011
-
In: Procedia Engineering. - : Elsevier. - 1877-7058. ; 25, s. 896-899
-
Journal article (peer-reviewed)abstract
- There is a need for low-cost mass-production circuits on various substrates, possibly performing some simple functions as switches, antennas, displays, and sensors. Also in the field of gas sensors widely used in several applications there is a need for such novel fabrication technologies and materials. In this paper, we present three gas sensor structures fabricated using novel printing techniques. Inkjet and gravure printing techniques were used for fabrication of resistive WO3 nanoparticle gas sensors for detection of NO, and inkjet printing was utilized for fabrication of solid electrolyte (mixture of H3PW12O40 and PVC) in a nanostructured Metal-Electrolyte-Insulator- Semiconductor (MEIS) transistor for detection of H2. The sensor structures were found to be sensitive for detection of NO below 10 ppm, and H2 below 100 ppm concentrations in synthetic air, respectively.
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