Search results for "Substrate"
showing 10 items of 1018 documents
ChemInform Abstract: Addition of Nucleophiles to Fluorinated Michael Acceptors.
2016
A series of nucleophiles, including primary and secondary amines, primary alcohols, and thiols, as well as diethyl malonate and nitromethane, were added to different fluorinated Michael acceptors including 2-fluoroalk-1-en-3-ones and 2-fluoro-1-phenylprop-2-en-1-one. The resulting β-substituted α-fluoro ketones were isolated in 34–92 % yield, depending on the substrate and the nucleophile. The best yields were obtained with secondary amines and with p-methylthiophenol.
Electrochemical Deoxygenation of Aromatic Amides and Sulfoxides
2014
The electrochemical deoxygenation of a broad range of aromatic amides was achieved under mild conditions on lead cathodes. Under the optimized reaction conditions, acetal, thienyl, and ether moieties are tolerated. Furthermore, the reduction protocol can be applied to aromatic and aliphatic sulfoxides to obtain the corresponding sulfides. For both aromatic amides and sulfoxides, the deoxygenation reaction ensues without the use of expensive catalysts or hazardous reducing agents. Owing to the high selectivity of the process, simple extraction is sufficient to isolate the product from the substrate. The straightforward purification protocol, the coformation of water, and the use of electric …
On the Reactivity of C(sp3)–H σ-Bonds: Oxygenation with Methyl(trifluoromethyl)dioxirane
2008
The reactivity of C–H σ-bonds of a series of 2-substituted adamantanes 2 towards methyl(trifluoromethyl)dioxirane (1) shows a consistent dependence on the electron-withdrawing ability, either inductive or by resonance, of the substituent. The results are interpreted in terms of the ability of the substrate molecule to delocalize the electronic perturbation of the reacting center at the beginning of the reaction path. The model shows that the electronic demand from the reacting C–H σ-bond is transmitted along the substrate through a chain of hyperconjugative interactions, the relative intensities of which depend on the σ-bonds involved. The substrate molecule simultaneously provides positive…
Enzyme replacement and gene therapy for mucopolysaccharidoses: current progress and future directions
2015
Introduction: Mucopolysaccharidoses (MPS) are lysosomal storage disorders caused by the deficiency of enzymes that are responsible for the stepwise degradation of complex carbohydrates, the glycosaminoglycans. Whereas in the past the treatment of MPS consisted mainly of palliative care, enzyme replacement therapy (ERT) is now possible for some MPS disorders, and in the future many other therapeutic options will become available.Areas covered: This review, based on personal experience and the currently available literature, will give an overview on the efficacy and limitations of ERT and will discuss new therapeutic approaches, such as anti-inflammatory drugs, substrate reduction therapy, ch…
Created substrates do not fully mimic natural substrates in restoration: the occurrence of polypores on spruce logs
2014
Many protected areas have been under intensive forest management prior to protection and thus lack natural ecosystem structures and dynamics. Dead wood is a key structure in forests harboring hundreds of threatened species. We investigated the ecological success of dead wood creation as a boreal forest restoration measure. We analysed whether the polypore communities of chain-saw felled and girdled (subsequently fallen) Norway spruce ( (L.) H. Karst.) logs differ from naturally formed spruce logs of similar decay stage and size. The study was conducted in Leivonmäki National Park in central Finland 8 years after the restoration measures. The average number of polypore species was highest o…
Effect of substrate particle size on burrowing of the juvenile freshwater pearl mussel Margaritifera margaritifera
2021
AbstractJuveniles of the endangered freshwater pearl mussel (FPM,Margaritifera margaritifera) live burrowed in stream substrate for the first years of their life. Fine sediments block water exchange within substrate and may cause juvenile mortality and recruitment failure. To better understand the connection between success of juvenile FPM and substrate particle size, it would be important to understand behavioural responses of FPM to varying substrate sizes at this critical life stage. We placed newly detached FPM juveniles in a 7-mm layer of sieved sand sorted into five sizes (< 120, 120–200, 200–250, 250–500 and 500–650 µm) each with 10 replicate dishes, 10 juveniles per dish, with bu…
The analysis of methods for measurement of methane oxidation in landfills
2003
Landfills and dumps are important sources of atmospheric methane. There is no generally accepted estimate of the influence of methane oxidation on landfill methane emissions. The present work aimed to analyse different methods for the investigation of methane emission and oxidation in methane-producing environments (wetlands, landfills, sludge checks), and to develop the precise procedure for the landfills. The combination of geochemical and microbiological methods to estimate and monitor the oxidation and emission of methane in landfills during different seasons is proposed. It includes the measurements, both on the surface and at different depths (up to 1 m) of landfill ground of the foll…
Population dynamics using temporal series analysis in a industrial two-stage activated sludge pilot plant
1998
A time series analysis using an autocorrelation function (ACF) was used to assess the relative importance of density (DD) and non density-dependent - (NDD) factors on microfauna abundance of a two-stage activated sludge pilot plant treating industrial effluents. Although some previous work has detected a carrying capacity for the total microfauna abundance in both reactors, ACF showed a general pattern of non-density dependent abundance regulation. Stationarity due to density-dependent factors was observed for the two major species in the first reactor, the sessile Opercularia asymmetrica and the crawling Chilodonatella minuta. There was no evidence of bacterial competition and only weak ev…
Population dynamics and tolerance to desiccation in a crustacean ostracod adapted to life in small ephemeral water bodies
2011
AbstractGiven their small size, isolation and unpredictability, temporary rockpools present high environmental stress and impoverished communities of species that have adapted to such stressful conditions. Special adaptations of the invertebrates living in these habitats include tolerance to desiccation and fast ontogenetic development in order to maintain stable populations and face high risk of extinction. Dozens of small rockpools (mostly with Ø<1m) can be found in east Spain on limestone substrate, where the only known Iberian populations of Heterocypris bosniaca Petkovski et al. (2000), an ostracod species with geographic parthenogenesis, have been recently found. In this survey, two o…
Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films
2018
A comparative study of mechanical properties and elemental and structural composition was made for aluminum nitride thin films deposited with reactive magnetron sputtering and plasma enhanced atomic layer deposition (PEALD). The sputtered films were deposited on Si (100), Mo (110), and Al (111) oriented substrates to study the effect of substrate texture on film properties. For the PEALD trimethylaluminum–ammonia films, the effects of process parameters, such as temperature, bias voltage, and plasma gas (ammonia versus N2/H2), on the AlN properties were studied. All the AlN films had a nominal thickness of 100 nm. Time-of-flight elastic recoil detection analysis showed the sputtered films t…