Search results for "Lene"
showing 10 items of 4480 documents
Structural induced modifications in blends of polyamide with gamma irradiated low density polyethylene
1992
Abstract Blends of gamma irradiated and unirradiated low density polyethylene and polyamide 6 were made in order to study possible modifications induced by this irradiation. Results indicate that blends with gamma irradiated polyethylene have structure and properties significantly different with respect to blends made with the unirradiated one. This difference has been ascribed to the formation of functionalized groups in the polyethylene chains, which interact with polyamide.
Studien zum Vorgang der Wasserstoffübertragung, 68. Die reduktive Überführung aromatischer Säurechloride in Diarylacetylene mit Lithiumamalgam in ein…
1983
Endioldiester A, die durch “Acylierende reduktive Dimerisierung” mit Lithiumamalgam (Li/Hg) nach (1) zuganglich sind, werden mit zwei weiteren Reduktionsaquivalenten nach (2) durch “Reduktive Eliminierung” in Acetylenderivate ubergefuhrt. Hierbei hat sich praparativ das Eintopfverfahren in der Zweistufenarbeitsweise bewahrt. Auch mit Natriumamalgam (Na/Hg) und Kaliumamalgam (K/Hg) gelingt die reduktive Eliminierung nach (2) sowohl von cis- als auch von trans-Endiol-diestern zu Acetylenverbindungen mit guten Ausbeuten. Voraussetzung fur den erfolgreichen Ablauf der Reaktion (2) ist die direkte Verknupfung von zwei Aromaten mit der C C-Doppelbindung in den Endiol-diestern. Endiol-diester mit …
Oxyfunctionalization of Aliphatic Esters by Methyl(trifluoromethyl)dioxirane
1996
The oxidation of lineal, cyclic, and bicyclic aliphatic p-chlorobenzoic and p-chorobenzenesulfonic acid esters 2 with methyl(trifluoromethyl)dioxirane (TFDO) (1) occurs at positions in the hydrocarbon chain distant from the directing group with a significant degree of selectivity to give the corresponding keto or hydroxy esters. Compounds 2 are relatively deactivated with respect to this oxidation due to the electron-withdrawing nature of the ester moiety. Methylene Cα−H and Cβ−H bonds remain unchanged in all cases, but tertiary Cβ−H bonds undergo oxidation with TFDO (1). Stereoelectronic factors are used to explain the faster reaction rate in competition experiments for the oxidation of en…
Polysarcosine-containing copolymers: Synthesis, characterization, self-assembly, and applications
2018
Although the first polysarcosine (pSar) synthesis by Wesseley et al. was reported almost a century ago, it was only recently that pSar gained broader attention and is considered a potential alternative of poly(ethylene glycol) (PEG). In contrast to polyethers, such as PEG, pSar is a polypeptoid based on the amino acid sarcosine, i.e. N-methylated glycine. As a polymer, pSar combines PEG-like properties, e.g., excellent solubility in water, protein resistance, low cellular toxicity and a non-immunogenic character, while being based on endogenous material. Sarcosine can be obtained in a simple one-step reaction of bromoacetic acid and methylamine, easily transferred into the sarcosine N-(thio…
Chlorotitanium (IV) tetradentate Schiff-base complex immobilized on inorganic supports: Support type and other factors having effect on ethylene poly…
2009
A titanium complex with [O,N,N,O]-type tetradentate Schiff base (LTiCl2), never used before in polymerization of olefins, was immobilized on silica- and magnesium-type carriers, and it was used in ethylene polymerization. The conducted research revealed that the catalytic properties of the complex LTiCl2 supported on those carriers were different for both the catalytic systems studied, and simultaneously they turned out different from those of the unsupported system. The supported catalysts require the use of Me3Al, Et3Al, or MAO as the activator to be able to offer high catalytic activities, whereas Et2AlCl is needed for the nonsupported catalyst. This finding, together with considerable c…
On the Correlations Between Constitution and Scintillation Properties in the p-Oligophenylene Series
1968
Abstract The paper deals with the problem: What properties are requested from an organic scintillator solute and what structural principles are given to realize, or at least to influence them especially by looking at the p-oligophenylene series? According to their importance and also in respect to more or less special purposes one can distinguish the following sequence: 1) An organic scintillator solute must have a sufficient solubility in all types of solvents used for this counting method. As a result of extensive systematic studies substitution of larger alkyl groups has been recognized as a very effective principle of solubilization. By use of branched, particularly long-chain branched …
Small angle scattering study of the structure of isotactic polypropylene-hydrogenated oligo(cyclopentadiene) blends
1996
Abstract Blends of isotactic polypropylene ( i PP) and hydrogenated oligo cyclopentadiene (HOCP) have been studied by means of small angle X-ray scattering in the temperature range 70–160°C. The structure of blends containing less than 25% HOCP is very similar to the one of plain i PP, i.e. lamellae whose thickness increases by increasing the temperature. Blends containing more than 25% HOCP are characterized by two kinds of lamellae formed by layers of i PP and amorphous material rich in i PP and in HOCP, respectively. The crystallizable i PP present in both phases crystallizes from the melt, in analogy to what happens in HDPE/HOCP blends and in agreement with the values of the crystallini…
Synthesis of a rod-based porous coordination polymer from a nucleotide as a sequential chiral inductor
2021
We report the two-step synthesis of a novel chiral rod-based porous coordination polymer (PCP). The chemical approach consists of the use of a previously prepared bis(ethylenediamine) copper monomer [Cu(en)]2(NO3)2 [where en = ethylenediamine] reacting with the cytidine 5′-monophosphate (CMP) nucleotide. The bis(ethylenediamine) copper compound—stabilized by axial coordination of nitrate counter-anions—reacts in the presence of sodium salt of CMP to yield right-handed copper(II) chains of P helicity with formula [Cu2(en)2(CMP)2]·5H2O (1). The axial coordination of the CMP2- ligands through the N3 and O2 sites (free nitrogen and carbonyl groups) of the cytosine nucleobase and oxygen atoms of…
Micropropagation of juvenile and adult Sorbus domestica L.
1991
Successful propagation of seedlings and mature trees of Sorbus domestica L. has been achieved by in vitro methods. Multiple shoot formation was obtained by placing shoot apices or nodal segments on a modified Schenck and Hildebrandt medium containing benzyladenine. Regenerated shoots were excised and induced to root on media with auxin. In the best treatments 75–85% of shoots from juvenile material rooted. Rooting capacity of shoots from mature explants was lower (30%) and was not improved by dipping the base of shoots in concentration solutions of indolebutyric or naphthaleneacetic acids. Plantlets were ultimately established in soil.
On the determination of underivatised fatty alcohol ethoxylates by electrospray ionisation–mass spectrometry
2006
Abstract The oligomers of fatty alcohol ethoxylates (FAEs) exhibit large sensitivity differences in mass spectrometry with electrospray ionisation (ESI–MS) and atmospheric pressure chemical ionization (APCI). Standards of the oligomers from m = 1 to 7 ethylene oxide units (EOs) and linear alkyl chains from n = 10 to 18 carbon atoms were infused to examine the relative sensitivities or response factors in several media. The response factors of the [M + H]+ and [M + Na]+ peaks in 9:1 acetonitrile/water and methanol/water media containing acid buffers increased following irregular patterns when n and m increased. In methanol/water the response factors depended on the parity of m, being larger …