Search results for "APR"

Aluminum complexes of sterically hindered tetradentate Schiff bases: Synthesis, structure, and reactivity toward ɛ-caprolactone

1997

Abstract The sterically hindered Schiff bases tbmSalenH2 [tbmSalen = N,N′-1,2-ethylenebis(3-tert-butyl-5-methylsalicylideneimine)] and tbmSalcenH2 [tbmSalcen = N,N′-trans-1,2-cyclohexanediyl-bis(3-tert-butyl-5-methylsalicylideneimine)] afforded a series of aluminum complexes of the general formulae [Al(tbmSalen)X] and [Al(tbmSalcen)X] (X = Cl, Me, Et). The molecular structure of [Al(tbmSalcen)Cl] was determined by single-crystal X-ray structural analysis which revealed a five-coordinate aluminum center with a distorted square pyramidal geometry. The alkyl complexes were found to oligomerize ɛ-caprolactone.

Mechanisms of photosensitization by drugs: Involvement of tyrosines in the photomodification of proteins mediated by tiaprofenic acid in vitro

1997

The photosensitizing potential of drugs must be related to their photoreactivity towards the target biomolecules. In this context, a representative photosensitizing drug (tiaprofenic acid) was co-irradiated with a model protein, bovine serum albumin (BSA). This led to a significant degree of protein crosslinking and to the formation of trace amounts of drug-BSA photoadducts. Amino acid analysis of the hydrolysed (HC1) protein showed that His and Tyr undergo a dramatic decrease (approx. 90%) as a consequence of drug-mediated photodynamic processes. When the drug was irradiated in the presence of the pure amino acids, extensive phototransformation of the latter was observed. Other photosensit…

α-Hydroxy-Isocaproic Acid (HICA)—Effects on Body Composition, Muscle Soreness and Athletic Performance

2013

Alfa-hydroxy-isocaproic acid (HICA) is an end product of leucine metabolism in human tissues such as muscle and connective tissue. Clinical and experimental studies indicate that HICA may be considered as an anti-catabolic substance. Intensive exercise leads not only to anabolism but also to catabolism in the muscle. The latter is associated with breakdown of muscle proteins and delayed-onset muscle soreness (DOMS). Several studies indicate that free branched-chain amino acids (BCAAs), especially leucine, and their transaminated metabolites, such as α-ketoisocaproic acid (KIC), may alleviate symptoms associated with exercise-induced catabolism. Recent findings suggest that HICA effectively …

Risk assessment of beauvericin, enniatins and fusaproliferin present in follow-up infant formula by in vitro evaluation of the duodenal and colonic b…

2014

Abstract In this study, 72 samples of follow-up infant formula of Spanish origin were analyzed for the presence of the mycotoxins beauvericin (BEA), enniatins (ENs) (A, A1, B, B1), and fusaproliferin (FUS). The samples analyzed were extracted three times with ethyl acetate and then the mycotoxins were identified and quantified using a liquid chromatography (LC) coupled to a diode array detector (DAD). The positive samples analyzed in this study were digested through a simulated gastrointestinal digestion model, which permit to simulate the physiological condition of the human gastrointestinal tract (duodenal and colonic compartments) in order to assess the bioaccessibility of the bioactive …

1963

Es wird gezeigt, das sich e-Caprolactam mit wasserfreiem Bromwasserstoff kationisch polymerisieren last und die dabei gebildeten Polymeren die Struktur von N-(Poly-e-aminocaproyl)-caprolactamen besitzen. Die charakteristische Diacylimidstruktur wird IR-spektroskopisch, durch die Hydroxamsaurereaktion und durch alkoholytische Abspaltung des C-terminalen Lactamringes nachgewiesen. Oligomerengemische, die durch kurzzeitige Umsetzung molarer Mengen an Caprolactam und Initiator bei 175–200°C erhalten werden, konnen durch Hochspannungspapierelektrophorese in einheitliche Individuen aufgetrennt werden. Die Umsetzung mit Hydroxylamin fuhrt zu Oligo-e-aminocapronhydroxamsauren, die sich mit Hilfe au…

1976

The thermal degradation of poly(oxycarbonylpentamethylene), (poly-e-caprolactone), (3), was investigated at 220°C and 80 mm Hg under nitrogen. 3 was found to be thermally much more stable than poly(oxycarbonylethylene), (poly-β-propiolactone), (1), although it decomposed faster than poly(oxycarbonyl-1,1-dimethylethylene), (polypivalolactone), (2). The reaction was of the first order with a rate constant of k=6,2.10−4 min−1 and proceeded via a “zipper mechanism” to yield monomeric e-caprolactone. Der thermische Abbau von Poly(oxycarbonylpentamethylen), (Poly-e-caprolacton), (3), wurde bei 220°C im Stickstoffstrom bei 80 mm Hg untersucht. Dabei wurde gefunden, das 3 thermisch wesentlich stabi…

Die Kationische ɛ-Caprolactam-Polymerisation. V. Die quantitative Bestimmung der N-Acyllactam-Gruppen bei der Initiierung mit wasserfreien Säuren und…

1971

Als Beitrag zur Aufklarung des Mechanismus der kationischen Caprolactam-Polymerisation mit wasserfreien Sauren (z. B. HCl) als Initiatoren wurde der Gehalt der C-terminal entstehenden N-Acyllactam-Endgruppen und anderer funktioneller Gruppen der gebildeten Oligo- und Polyamide quantitative bestimmt. Dies erfolgte auf IR-spektroskopischem Wege und durch potentiometrische Titration der nach alkalischer Hydrolyse gebildeten Carboxylgruppen. Fur die Polymerisation wurde ein verbessertes Verfahren ausgearbeitet, das vollstandigen Sauerstoff- und Feuchtigkeitsausschlus ermoglicht und damit besser reproduzierbare Ergebnisse liefert. Die Abhangigkeit der Konzentration verschiedener funktioneller Gr…

Über den thermischen abbau des poly(ɛ-caprolacton)s

1977

The thermal and electron impact induced degradation reactions of poly(e-caprolactone) {poly[oxy(1-oxohexamethylene)]} were investigated in a mass spectrometer. It can be shown that the favorated thermal degradation reaction is the cleavage of the ester bond and formation of ω-hydroxyl and ketene endgroups (Eq. (iii)) and with a lower intensity the cleavage of the OCH2-bond and formation of carboxyl-and pentenyl endgroups (Eq. (vii)). After electron impact and fragmentation of the pyrolysis products to carboxonium ions an elimination of caprolactone via a “zip”-mechanism can be observed (Eq. (v)).

Normal-weight obesity and cardiometabolic risk : A 7-year longitudinal study in girls from prepuberty to early adulthood

2017

Objective: To study whether normal-weight obesity in childhood is associated with increased cardiometabolic risk in early adulthood. Methods: This study assessed data for 236 girls followed from prepuberty to early adulthood. Growth chart data were obtained from birth to 18 years. Body composition was assessed by dual-energy x-ray absorptiometry and cardiometabolic risk by calculating continuous clustered risk score (at ages 11, 14, and 18). The association of body weight status with cardiometabolic risk from childhood to early adulthood was examined. Results: Subjects with normal-weight obesity were virtually indistinguishable from their normal-weight lean peers in terms of relative body w…

Chrząszcze saproksyliczne Karkonoszy. Część I - wykaz gatunków

2016

Założenia. W północnej (polskiej) części Karkonoszy nie prowadzono dotychczas gruntownych studiów fauny związanej z obumierającymi drzewami i rozkładającym się drewnem, mimo że w latach osiemdziesiątych i dziewięćdziesiątych ubiegłego wieku środowisko tych gór zostało dotknięte klęską zamierania lasów. Do dzisiaj, w wyniku procesów rozpadu drzewostanów, utrzymuje się wysoki zapas martwych drzew i rozkładającego się drewna. Celem przeprowadzonych prac inwentaryzacyjnych było rozpoznanie chrząszczy saproksylicznych występujących w środowiskach leśnych Karkonoszy. Materiał i metody. Prace realizowano w latach 2013–2015 w 10 obiektach badawczych reprezentujących środowiska lasów regla dolnego, …