Search results for "Formaldehyde"
showing 10 items of 111 documents
(Ag)Pd-Fe3O4 Nanocomposites as Novel Catalysts for Methane Partial Oxidation at Low Temperature
2020
Nanostructured composite materials based on noble mono-(Pd) or bi-metallic (Ag/Pd) particles supported on mixed iron oxides (II/III) with bulk magnetite structure (Fe3O4) have been developed in order to assess their potential for heterogeneous catalysis applications in methane partial oxidation. Advancing the direct transformation of methane into value-added chemicals is consensually accepted as the key to ensuring sustainable development in the forthcoming future. On the one hand, nanosized Fe3O4 particles with spherical morphology were synthesized by an aqueous-based reflux method employing different Fe (II)/Fe (III) molar ratios (2 or 4) and reflux temperatures (80, 95 or 110 °
Template-controlled synthesis of chiral cyclohexylhemicucurbit[8]uril
2015
Enantiomerically pure cyclohexylhemicucurbit[8]uril (cycHC[8]), possessing a barrel-shaped cavity, has been prepared in high yield on a gram scale from either (R,R,N,N')-cyclohex-1,2-diylurea and formaldehyde or cycHC[6]. In either case, a dynamic covalent library is first generated from which the desired cycHC can be amplified using a suitable anion template.
Patch test results with the metalworking fluid series of the German Contact Dermatitis Research Group (DKG).
2004
Based on the information of the interdisciplinary task force on allergy diagnostics in the metal branch, in 2001, the German Contact Dermatitis Research Group (DKG) compiled two metalworking fluid (MWF) test series with currently and previously used components, respectively. After 2 years of patch testing, we present results obtained with these series, based on data of the Information Network of Departments of Dermatology (IVDK). 251 metalworkers who were patch tested because of suspected MWF dermatitis in 2002 and 2003 were included in this retrospective data analysis. Of these, 206 were tested with the current MWF series and 155 with the historical MWF series. Among the current MWF allerg…
A Molecular Electron Density Theory Study of the Competitiveness of Polar Diels–Alder and Polar Alder-ene Reactions
2018
Indexación: Scopus. Funding: Ministry of Economy and Competitiveness (MINECO) of the Spanish Government, project CTQ2016-78669-P (AEI/FEDER, UE) and Fondecyt (Chile) grant 1180348. Acknowledgments: This research was supported by the Ministry of Economy and Competitiveness (MINECO) of the Spanish Government, project CTQ2016-78669-P (AEI/FEDER, UE) and Fondecyt (Chile) grant 1180348. L.R.D. thanks Fondecyt for continuous support through Cooperación Internacional. M.R.-G. also thanks MINECO for a post-doctoral contract cofinanced by the European Social Fund (BES-2014-068258). The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions …
Piperazine bridged resorcinarene cages.
2010
The one-pot Mannich condensation of resorcinarenes with piperazine and an excess of formaldehyde under high dilution conditions results in a helical cage, namely, a covalently linked dimer of two resorcinarenes connected via four piperazine bridges in yields ranging from 20 to 40%. The compounds were analyzed by NMR spectroscopy, ESI mass spectrometry, and single crystal X-ray diffraction. The helical cages can encapsulate small guest molecules by adapting the cavity volume by changing the helical pitch according to the guest size.
The role of water in the photocatalytic degradation of acetonitrile and toluene in gas-solid and liquid-solid regimes
2006
Photocatalytic degradation of acetonitrile and toluene was carried out both in gas-solid and in liquid-solid regimes by using commercialTiO2samples (Merck and Degussa P25). The investigation was mainly aimed to study the influence of water present in the reaction environment on the mechanism and degradation rate of two probe molecules. In gas-solid regime, the reacting mixture consisted of toluene or acetonitrile, oxygen, nitrogen, and water vapour. The main degradation product of toluene wasCO2with small amounts of benzaldehyde. In the presence of water vapour, the activity ofTiO2Merck remained stable but greatly decreased if water was absent.TiO2Degussa P25 continuously deactivated, even …
Release of naltrexone on buccal mucosa: Permeation studies, histological aspects and matrix system design
2007
Transbuccal drug delivery has got several well-known advantages especially with respect to peroral way. Since a major limitation in buccal drug delivery could be the low permeability of the epithelium, the aptitude of NLX to penetrate the mucosal barrier was assessed. Ex vivo permeation across porcine buccal mucosa 800 microm thick was investigated using Franz type diffusion cells and compared with in vitro data previously obtained by reconstituted human oral epithelium 100 microm thick. Both fluxes (Js) and permeability coefficients (K(p)) are in accordance, using either buffer solution simulating saliva or natural human saliva. Permeation was evaluated also in presence of chemical enhance…
Monoclonal antibodies SMI 311 and SMI 312 as tools to investigate the maturation of nerve cells and axonal patterns in human fetal brain
1998
Neurofilaments, which are exclusively found in nerve cells, are one of the earliest recognizable features of the maturing nervous system. The differential distribution of neurofilament proteins in varying degrees of phosphorylation within a neuron provides the possibility of selectively demonstrating either somata and dendrites or axons. Non-phosphorylated neurofilaments typical of somata and dendrites can be visualized with the aid of monoclonal antibody SMI 311, whereas antibody SMI 312 is directed against highly phosphorylated axonal epitopes of neurofilaments. The maturation of neuronal types, the development of area-specific axonal networks, and the gradients of maturation can thus be …
Synthesis, characterization and thermal degradation of 8-hydroxyquinoline–guanidine–formaldehyde terpolymer
2007
Abstract Terpolymer (8-HQGF) has been synthesized using the monomers 8-hydroxyquinoline, guanidine, formaldehyde in 1:1:2 molar proportions. The structure of 8-HQGF terpolymer has been elucidated on the basis of elemental analysis and various physicochemical techniques, i.e. UV–Visible, FTIR–ATR and 1 H NMR spectroscopy. Detailed thermal degradation study of the new terpolymer has been carried out to ascertain its thermal stability. Thermal degradation curve is discussed which shows two decomposition steps (265–475 °C and 540–715 °C). Sharp–Wentworth and Freeman–Carroll methods have been used to calculate activation energies and thermal stability. The activation energy ( E a ) calculated by…
Die kolorimetrische bestimmung von konstitutions und molekulareinheitlichen phenol-formaldehyd-kondensaten in methanolischer lösung mit FeCl3
1961
Phenol-Formaldehyd-Kondensate, die bestimmte Atomgruppierungen (vor allem zur phenolischen Gruppe ortho-standige Hydroxymethylgruppen) besitzen, geben in methanolischer Losung mit FeCl3 · 6H2O eine Farbreaktion. Es werden die Bedingungen mitgeteilt, unter denen die Extinktion der Farbreaktion reproduzierbar und innerhalb der Meszeit konstant ist. Bei Eisen(III)-chlorid-Konzentrationen von 0,24 bis 0,6 [Mol/1] ist die Extinktion linear abhangig von der Konzentration der Phenol-Formaldehyd-Kondensate. Die Extinktionen von Gemischen derartiger Kondensate verhalten sich additiv. Die analytische Anwendbarkeit der Farbreaktion wird erortert. In methanolic solution phenol-formaldehyde condensates …