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1.
Laila Čakare Marija Kosec Barbara Malič 《Journal of Sol-Gel Science and Technology》2000,19(1-3):603-606
PbZrO3 (PZ) thin films have been prepared by 2-methoxyethanol route from lead oxide or lead acetate and zirconium n-butoxide. The use of lead oxide as lead source and the seeding layer of TiO2 on Pt/TiO2/SiO2/Si substrate facilitate the formation of the perovskite phase. 相似文献
2.
Amorphous precursors for PbZrO3 and PbTiO3 ceramics were prepared from lead acetate and the transition metaln-propoxide inn-propanol orn-butoxide inn-butanol and hydrolysed with an excess of water.
According to GLC and TGA/EGA analyses, the type of alkoxide group influences distinctly the structure of heterometallic precursors,
i.e., oxo or acetate bridging, and the amounts of hydroxyl and organic groups bound to the metal network.
The local environments of metal atoms in the amorphous precursors were also studied by EXAFS. The analysis reveals that in
Pb−Zr precursors alkoxide groups modify the coordination spheres of the zirconium atoms. Conversely, local environments of
both lead and titanium atoms within the analysed range of 3.4 A depend weakly on the type of alkoxide used. 相似文献
3.
Pollak C Malic B Kosec M Javoric S Hutter H 《Analytical and bioanalytical chemistry》2002,374(4):608-613
Chemical solution-deposited thin films of PbZr(0.53)Ti(0.47)O(3)/La(0.5)Sr(0.5)CoO(3) on Pt/TiO(2)/SiO(2)/Si substrates have been investigated by dynamic SIMS. The PbZr(0.53)Ti(0.47)O(3) (PZT) is intended to serve as a ferroelectric layer for microelectronic or microelectromechanical applications; conducting La(0.5)Sr(0.5)CoO(3) (LSCO) is a buffer layer intended to eliminate fatigue effects which usually occur at the Pt/PZT interface. Depth profiles of the main components were obtained and revealed that significant diffusion occurred during the deposition and crystallisation processes. Two types of sample, with different thickness of PZT and different types of poly(vinyl alcohol) (PVA) added to the LSCO precursor, were investigated. 相似文献
4.
Pb(Zr0.50Ti0.50)O3 solid solution was prepared using lead acetate and transition metal n-propoxides in n-propanol or n-butoxides in n-butanol. The complex solutions were hydrolysed with an excess of H2O. The resultant powders were calcined up to 700°C for 30 minutes in a flowing oxygen atmosphere. Scanning electron microscope analysis showed different morphologies of the resultant powders. The n-propoxide derived powder consisted of gel fragments, while the n-butoxide derived one had agglomerated submicrometre particles. EDS analysis of the powders revealed no chemical heterogeneities in the examined samples upon calcining up to 600°C, notwithstanding the type of precursor used. Both samples, calcined at 700°C, exhibited a slight deficiency of lead in the pyrochlore type phase as compared to the perovskite phase. 相似文献
5.
Construction of a New Class of Tetracycline Lead Structures with Potent Antibacterial Activity through Biosynthetic Engineering
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Dr. Urška Lešnik Dr. Tadeja Lukežič Dr. Ajda Podgoršek Dr. Jaka Horvat Dr. Tomaž Polak Dr. Martin Šala Branko Jenko Dr. Kirsten Harmrolfs Dr. Alain Ocampo‐Sosa Prof. Dr. Luis Martínez‐Martínez Dr. Paul R. Herron Dr. Štefan Fujs Dr. Gregor Kosec Prof. Dr. Iain S. Hunter Prof. Dr. Rolf Müller Prof. Dr. Hrvoje Petković 《Angewandte Chemie (International ed. in English)》2015,54(13):3937-3940
Antimicrobial resistance and the shortage of novel antibiotics have led to an urgent need for new antibacterial drug leads. Several existing natural product scaffolds (including chelocardins) have not been developed because their suboptimal pharmacological properties could not be addressed at the time. It is demonstrated here that reviving such compounds through the application of biosynthetic engineering can deliver novel drug candidates. Through a rational approach, the carboxamido moiety of tetracyclines (an important structural feature for their bioactivity) was introduced into the chelocardins, which are atypical tetracyclines with an unknown mode of action. A broad‐spectrum antibiotic lead was generated with significantly improved activity, including against all Gram‐negative pathogens of the ESKAPE panel. Since the lead structure is also amenable to further chemical modification, it is a platform for further development through medicinal chemistry and genetic engineering. 相似文献
6.
Darja Jenko Andreja Bencan Barbara Malic Janez Holc Marija Kosec 《Microscopy and microanalysis》2005,11(6):572-580
Using electron microscopy, K0.5Na0.5NbO3 (KNN) ceramics sintered at 1030 degrees C for 8 h and 1100 degrees C for 2 and 24 h was studied. The scanning electron microscopy and X-ray spectrometry revealed that the materials consisted of a matrix phase in which the (Na+K)/Nb ratio corresponded closely to the nominal composition and a small amount of Nb-rich secondary phase. A bimodal microstructure of cube-shaped grains was revealed in the fracture and thermally-etched surfaces of the KNN. In the ceramics sintered at 1100 degrees C, the larger grains (up to 30 mum across), contained angular trapped pores. The transmission electron microscopy analysis revealed that the crystal planes of the grains bordering the intragranular pore faces were of the {100} family with respect to the simple perovskite cell. Ferroelectric domains were observed in the grains of this material. 相似文献
7.
E. D. Ion B. Malič I. Arčon A. Kodre M. Kosec 《Journal of Sol-Gel Science and Technology》2008,45(2):213-218
PbZrO3 powders have been prepared by an alkoxide-based sol–gel route, starting from lead acetate, zirconium n-butoxide, and n-butanol as a solvent, and hydrolysed with different amounts of water in neutral and alkaline medium. The local environment
of Zr and Pb atoms was pursued from the sol to the dried (150 °C) and heated (400 °C) powders, by extended x-ray absorption
fine structure (EXAFS). The analysis of the sol revealed links between Pb and Zr, and even more links between Zr and Zr. The
metal neighbourhoods in the dried powders are not influenced by the hydrolysis conditions. Pb-Zr correlations are gradually
lost from the sol to the dried and heated powders, while the loss of Zr–Zr correlations is considerably lower. 相似文献
8.
Sebastjan Glin?ek Iztok Ar?on Barbara Mali? Alojz Kodre Marija Kosec 《Journal of Sol-Gel Science and Technology》2012,62(1):1-6
The KTa0.6Nb0.4O3 sols for chemical solution deposition of thin films were prepared from potassium acetate and transition metal ethoxides by
the 2-methoxyethanol based route. The local environment of both transition metals after reflux times 1, 4, 24, and 48 h, whereby
the crystallization behavior of the films was strongly affected, was monitored by extended X-ray absorption fine structure
spectroscopy, at Ta L3 and Nb K edges. The Ta species existed in the sols as monomers, remaining stable even with prolonged reflux time. The Ta–O–K
correlations were confirmed in all cases. In contrast, the Nb-alkoxide formed dimers, with a gradual formation of oligomeric
species with prolonged refluxing. The Nb–O–K correlations were present after all reflux times. The number of K neighbours
around Nb increased upon refluxing, saturating at 24 h. 相似文献
9.
Elena-Daniela Ion Barbara Malic Marija Kosec 《Journal of Sol-Gel Science and Technology》2007,44(3):203-209
Fine lanthanum zirconate powder was prepared by thermally decomposing a nitrate-alkoxide-based precursor derived from dehydrated
lanthanum nitrate, zirconium n-butoxide and 2-methoxyethanol. Upon heating, the decomposition of the organic groups was promoted by the nitrate groups,
yielding a porous powder that crystallized into a pyrochlore phase at 800 °C. The powder that was heat treated at 900 °C for
1 h was composed of friable agglomerates of approximately 60-nm-sized nanoparticles. The ceramics obtained from the powder
heat treated at 900 °C and milled for 30 min reached a relative density of 97.9 % after sintering at 1,400 °C for 10 h, which
is at least 100 °C lower than the typically reported temperatures for this material. 相似文献
10.
Malič Barbara Kosec Marija Arčon Iztok Kodre Alojz 《Journal of Sol-Gel Science and Technology》2000,19(1-3):153-156
PbTiO3 (PT) thin films and their respective sols derived from three lead sources have been studied in order to elucidate the role of the starting materials in the crystallization of the products. EXAFS analysis of sols revealed similar oligomeric Ti-units in PT precursors derived from lead oxide or lead 2-methoxyethoxide acetate and a significantly different local Ti neighborhood in those derived from lead acetate. Structural details of the perovskite phase in the thin films follow the same pattern of similarity. 相似文献