Two new asymmetrical bis-spiropyrans with nonequivalent spiropyran units have been investigated. Hydroxyethyl and carboxyethyl substituents have been used to improve thermal stability of the ...photoinduced merocyanine forms of the bis-spiropyrans. 2-Hydroxyethyl substituted compound is characterized by 4 times more stable merocyanine isomer. 2-Carboxyethyl substituent in the hetarene part enables chelation by metal ions and controllably stabilizes the merocyanine from thermal decay. As a result of theoretical modeling and photochemical experiments, it was shown that obtained compounds are perspective prototypes for multistate light-driven switches with improved stability of photoinduced forms.
Asymmetric indoline-benzoxazine bis-spiropyran showing improved photochromic properties due to the electron-donating methoxy group has been prepared by multistage synthesis. The molecular structure ...of 8-methoxy-3-methyl-4-oxo-2
H
-1,3-benzoxazine-2-spiro-2′
H
,8′
H
-pyrano-2,3-
f
chromene-8′-spiro-2″-1″,3″,3″-trimethylindoline has been studied by X-ray diffraction. After exposure to UV light, the absorption spectra display several long-wavelength maxima, which can correspond to different merocyanine isomers of the bis-spiro compound.
A Gleeble 3800 thermomechanical process physical simulator unit is used to study the structure and mechanical properties of corrosion-resistant steel with a high boron content intended for production ...of hexagonal pipes for exhausted nuclear fuel storage. Compression tests at room and elevated temperature show that with an increase in test temperature from 20 to 600°C yield strength and flow stress decrease by a factor of two in the steady-state stage, and over the whole test temperature range the steel demonstrates good ductility in compression. The steel’s structure does not undergo marked changes during deformation: stringing, formed during hot forging, is retained during subsequent plastic deformation.
Solid state photochromism of spiropyrans Lukyanov, B. S.; Metelitsa, A. V.; Voloshin, N. A. ...
International Journal of Photoenergy,
01/2005, Letnik:
7, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A series of spiropyrans possessing photochromic properties in solid state were investigated. UV irradiation ( λ max = 365 nm) of the thin vacuum deposited spiropyran films results in conversion of ...the colorless form to the photocolored one. The reaction is photochemically and thermally reversible. The photochromic activity of the solid material and polystyrene matrix has been compared. Raman spectroscopy has been used for studying the influence of metallic surface on the adsorbed spiropyran layers.
A new unsymmetrical bisspiropyran was synthesized on the basis of 2,4-dihydroxyisophthalic aldehyde with naphthoxazinone and indoline fragments in the structure. The structure of the obtained ...compound was proved by the data from ¹H NMR and IR spectroscopy and X-ray crystallographic analysis. The photochromic characteristics of the obtained compound were investigated. It was established by means of the data from B3LYP/6-31G** quantum-chemical calculations that irradiation of a solution of the obtained biphotochrome with unfiltered light leads to opening of both pyran fragments. This is the first corroborated example of the twofold cleavage of Cspiro-O bonds for compounds of this class.
Indoline-derived spiropyrans, the precursors of nonsymmetric bis-spiropyrans, which are the promising prototypes of multistate molecular switches, were synthesized based on ...4,6-diformyl-2-methylresorcinol. Molecular structure of one of these compounds was studied by X-ray diffraction analysis. Photochemical studies showed the presence of photochromic properties in the obtained spiropyrans at room temperature.
To reduce the incidence of postoperative complications and mortality after conversion of external fixation device into various types of submerged osteosynthesis in patients with polytrauma.
A ...retrospective and prospective analysis of treatment outcomes in 351 patients with polytrauma was divided into 2 stages. At the first stage, we analyzed significant predictors of complications after conversion of osteosynthesis in the 1
group (retrospective analysis). At the second stage, we estimated the efficacy of the developed scale for assessing the risk of complications after conversion of osteosynthesis in a prospective group of patients.
According to the complication risk assessment scale for conversion of osteosynthesis, analysis of time to surgical treatment depending on objective criteria in patients with polytrauma can significantly reduce the incidence of postoperative complications by 14% and mortality rate by 1.7%.
The complication risk assessment scale after conversion of osteosynthesis will personalize the approach to timing and methods of conversion. This measure will eliminate the «second hit» in damage control orthopedics and improve the results of treatment.
Known preparation methods of the magnetic sorbents based on exfoliated graphite (EG) with metallic phase take several hours and requires the use of a large amount of reducing gas at a high ...temperature, which is not technologically advanced. The aim of the work is to obtain EG modified with iron, cobalt, and nickel using new simple method. This method includes the thermal treatment in nitrogen atmosphere of the mixture of expandable graphite, Mn+ nitrates (Mn+ = Fe3+, Co2+, Ni2+) and melamine. The thermal decomposition of melamine leads to formation of ammonia, which reduces the products of the Mn+ nitrates decomposition (α-Fe2O3, Co3O4/CoO, NiO) to metallic iron, cobalt and nickel. The use of different amount of melamine as reducing agent leads to the formation of mixtures with different compositions containing iron oxides Fe3O4, FeO, metallic iron α-Fe, Fe-C alloy γ-(Fe,C) and iron carbide Fe3C, which were confirmed by Mossbauer spectroscopy. Metallic Co and Ni on the EG surface is formed in nitrogen atmosphere by reduction with carbon even without melamine. Obtained EG/Fe has the highest saturation magnetization of 54.7 emu/g. EG/Co and EG/Ni have lower saturation magnetization of 40.1 and 12.0 emu/g, which is due to lower saturation magnetization of the individual metals.
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•Exfoliated graphite with Fe, Co, Ni was obtained in a nitrogen atmosphere.•Melamine, decomposing with the formation of NH3, was used as a reducing agent.•EG/Fe exhibits the highest saturation magnetization compared to EG/Co, EG/Ni.•EG/Fe can be used as a magnetic sorbent for oil recovery from the water surface.
Some spiropyrans containing functional substituents in the
2
H
-chromene part of the molecule were synthesized and their photochromic properties in solution and solid state were investigated. The ...presence of the formyl group in the
2
H
-chromene fragment enhances the possibility to show photochromic properties in solution.
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