Search results for "MAM"
showing 10 items of 1679 documents
Interpolymer complexes and polymer compatibility.
2012
A reliable method to decide whether two polymers A and B are miscible or incompatible would be very helpful in many ways. In this contribution we demonstrate why traditional procedures cannot work. We propose to use the intrinsic viscosities [η] of the polymer blends instead of the composition dependence of the viscosities as a criterion for polymer miscibility. Two macromolecules A and B are miscible because of sufficiently favorable interactions between the two types of polymer segments. For solutions of these polymers in a joint solvent, this Gibbs energetic preference of dissimilar intersegmental contacts should prevail upon dilution and lead to the formation of interpolymer complexes, …
Regulation of the Urea Cycle during Lactation
1990
We have recently shown that the uptake of amino acids by rat lactating mammary gland is 15 mmoles/day (1). This effect is achieved by an increase in food intake during lactation and probably by changes in amino acid metabolism in other tissues. Rat liver removes 75% of the total amino acids derived from a protein meal (2); therefore plays a key role in the regulation of plasma amino acid concentration.
Sildenafil protects human mammary epithelial cells against ROS production induced by estradiol
2010
Several studies suggest that xanthine dehydrogenase (XDH) and its oxidase form (XO) play an important role in various types of ischemic and vascular injuries. Recently, we have demonstrated that estradiol (E2) induces a significant decrease of the expression and activity of XDH and of its conversion to XO in human mammary epithelial cells. E2 is known to induce upregulation of eNOS gene expression in aortic endothelial cells. Because the XO-derived O2·- combines with ·NO to yield ONOO-, and considering that ONOO- converts XDH to XO, the resulting increase of XO activity and reactive oxygen species production would eventually lead to a further increase of ONOO- production, thus creating a vi…
7-Amino-2-methylsulfanyl-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxylic acid as the dimethylformamide and water monosolvates at 293 K.
2010
The molecular structure of 7-amino-2-methylsulfanyl-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxylic acid is reported in two crystal environments, viz. as the dimethylformamide (DMF) monosolvate, C(7)H(7)N(5)O(2)S·C(3)H(7)NO, (I), and as the monohydrate, C(7)H(7)N(5)O(2)S·H(2)O, (II), both at 293 (2) K. The triazolo[1,5-a]pyrimidine molecule is of interest with respect to the possible biological activity of its coordination compounds. While the DMF solvate exhibits a layered structural arrangement through N...O hydrogen-bonding interactions, the monohydrate displays a network of intermolecular O...O and N...O hydrogen bonds assisted by cocrystallized water molecules and weak π-π stacking intera…
Viscometric study on the compatibility of polymer–polymer mixtures in solution
1999
Abstract The viscosity behaviour of mixtures formed by two uncharged polymers in dilute solution has been studied at 25°C. The ternary systems assayed, and denoted solvent (1)/ polymer (2)/ polymer (3), have in common the poly(ether sulphone) (PES) as polymer 2, and poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA) or poly(styrene) (PS) as polymer 3. The intrinsic viscosity and the viscometric interaction parameters have been experimentally measured for the binary (solvent/polymer) as well as for the ternary systems, and also theoretically evaluated for the latter. The estimation of the compatibility degree of the above polymer pairs have been done by means of three criteri…
Über umsetzungen an poly-p-lithiumstyrol. 4. Mitt. Darstellung carbonylgruppenhaltiger derivate des polystyrols
1961
In Fortsetzung fruherer Arbeiten wird die Reaktivitat von Poly-p-lithiumstyrol gegenuber solchen Agenzien gepruft, die zur Bildung von carbonylgruppenhaltigen Verbindungen fuhren. Wahrend bei der Umsetzung mit Orthoameisensaureester nur vernetzte Polymere entstechen, last sich mit Dimethylformamid ein losliches Derivat des Polystyrols herstellen das p-standige Formylgruppen tragt. Die Reaktion mit Nitrilen liefert polymere Ketone; mit Acetophenon entsteht Poly-p-vinylacetophenon, das mit dem aus dem Monomeren durch Polymerisation erhaltenen Produkt verglichen wird. Mit Benzonitril erhalt man Poly-p-vinylbenzophenon. Die polymeren Ketone konnen in die Oxime ubergefuhrt werden, deren Sticksto…
Imidazolsynthesen, Mitt. Synthese α-substituierter 4(5)-Methoxymethyl-5(4)-methyl-imidazole
1977
Methoxymercurierung der α,β-ungesattigten Ketone 1 ergibt α-Acetoxymercuri-β-methoxy-ketone 2, die direkt zu α-Brom-β-methoxy-ketonen 3 bromo- demercuriert werden. Cyclisierung von 3 mit Formamidinacetat in flussigem Ammoniak fuhrt zu α-substituierten 4(5)-Methoxy-methyl-5(4)-methyl-imidazolen 4, deren Struktur 13C-NMR-spektroskopisch gesichert ist. Synthesis of α-Substituted 4(5)-Methoxymethyl-5(4)-methylimidazoles Methoxymercuration of the α,β-unsaturated ketones 1 produces the α-acetoxymercury-β-methoxyketones 2, which are bromo-demercurised without isolation to give the α-bromo-β-methoxyketones 3. Cyclisation of 3 with formamidine acetate in liquid ammonia leads to α-substituted 4(5)-me…
Über makrozwitterionen, 9. Über den mechanismus der anionischen polymerisation von acrylnitril mit tertiären phosphinen unter Zusatz von LiCl
1974
Die anionische Polymerisation von Acrylnitril mit tertiaren Phosphinen in Dimethylformamid bei 25°C wurde unter Zusatz von LiCl untersucht. Es zeigte sich, das durch den Salzzusatz mit Triphenylphosphin als Initiator eine Polymerisation uber Makrozwitterionen ermoglicht wird und mit Triathylphosphin die (auch ohne Salzzusatz schon mogliche) Makrozwitterionenbildung starker auftritt. The effect of LiCl on the polymerization of acrylonitrile initiated by tertiary phosphines at 25 C in dimethylformamide was studied. Macrozwitterions are formed only in the presence of the added salt when triphenylphosphine is used as an initiator. In the system initiated by triethylphosphine formation of macroz…
Die kolorimetrische bestimmung höhermolekularer phenol-formaldehyd-kondensate in dimethylformamid-methanol-lösung mit FeCl3
1961
Phenol-Formaldehyd-Kondensate geben in einem Gemisch aus Dimethylformamid und Methanol (4:1, Vol.) mit FeCl3 · 6H2O eine Farbreaktion. Es konnten Bedingungen ausfindig gemacht werden, unter denen die Extinktion der Farbreaktion reproduzierbar und innerhalb der Meszeit konstant ist. Diese Farbreaktion wird von konstitutions- und molekulareinheitlichen Phenol-Formaldehyd-Kondensaten bis zum Molekulargewicht 900 gegeben, selbst wenn sie keine Hydroxymethylgruppen besitzen. Bei der Kondensation von 2,6-Dihydroxymethyl-4-methylphenol zu Polyhydroxydibenzylathern (Molekulargewicht bis 3400) zeigt sich eine charakteristische, hypsochrome Verschiebung des Absorptions maximums, wahrend die sauer erh…
Preparation of monohalopyrroles
1982
Monobromo-, monochloro- and monoiodopyrroles are obtained in excellent yields by using N-halosuccinimides in dimethylformamide as halogenating agents.