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[en] Results are reported from a search for periodicities in the X-ray emission from cataclysmic variables observed with the Einstein Observatory's IPC at 0.16-3.5 keV and 0.01-2.5 Hz. Power spectra are shown for 51 observations of 31 systems, and upper limits are derived to the pulse fractions of signals that are not detected. The majority of systems show no coherent periodicities in their X-ray emission, which is consistent with a model in which the X-rays are produced in a disk/white-dwarf boundary layer. 27 refs
Journal
[en] This paper describes a kinetic study of the isotopic substitution reaction, (where Et = C2H5), trans-HPtCl (PEt3)2 + D2O---» trans-DPtCl (PEt3)2 +HDO, in aqueous acetone solution. The decrease in the intensity of the Pt-H infrared band at 2196 cm-1 was used to follow the reaction. The reaction was found to be catalysed by D+ and Cl'according to the approximate rate-law: -d [HPtCl (PEt3)2]/dt = (k1 + k2[Cl-]) [D+] [HPtCl(PEt3)2] where k1 = 4.1 x 10-2 M-1 sec-1 and k2 = 6.0 M-2 sec-1 at 30° in 75% acetone - 25% D2O by volume. The rates of both the Cl- -independent and Cl- dependent paths exhibited an inverse dependence on the D2O content of the solvent and, in addition, the apparent kinetic dependence of the latter path on the Cl- -concentration became higher than first-order at low D2O concentrations. The Cl- -catalysed exchange path, corresponding to the k2 term in the rate-law, is interpreted in terms of a mechanism involving reversible addition of DCl to the coordination shell of the platinum complex to give a hexa-coordinated PtIV intermediate, i.e.: An analogous mechanism in which a solvent molecule replaces the entering Cl- ion is invoked to account for the Cl- -independent (i.e. k1) path. This interpretation predicts that the Cl- -catalysed substitution of H by D should be accompanied by exchange of the Cl- ligand of the complex with isotopically-labelled Cl' in the solution. Experiments to test this are described. (author)
[fr]
L'objet du mémoire est une étude cinétique de la réaction de substitution isotopique trans-HPtCl (PEt3)2 + D2O---» trans-DPtCl (PEt3)2 +HDO, en solution aqueuse d'acétone, où Et = C2H5. On a observé la diminution de l'intensité de la bande infrarouge du Pt-H à 2196 cm-1 pour suivre la réaction. Les auteurs ont constaté que cette réaction est catalysée par D+ et Cl- d'après la loi de vitesse proche de: -d [HPtCl (PEt3)2]/dt = (k1 + k2[Cl-]) [D+] [HPtCl(PEt3)2] ou k1 = 4.1 x 10-2 M-1 sec-1 et k2 = 6.0 M-2 sec-1 à 30° dans une solution à 75% d'acétone et 25% de D2O en volume. Les vitesses des voies indépendantes et dépendantes de Cl- sont inversement proportionnelles à la teneur du solvant en D2O; de plus, la dépendance cinétique apparente de la seconde voie, selon la concentration en Cl-, a dépassé le premier ordre pour des concentrations faibles en D2O. La voie de réchange catalysé par l'ion Cl- , correspondant au terme k2 dans la loi de vitesse, est interprétée en ayant recours à un mécanisme impliquant une addition réversible de DC1 à la couche de coordination du complexe de platine, de manière à donner un composé intermédiaire de PtIV hexacoordonné (voir diagramme dans le résumé en anglais). Les auteurs invoquent un mécanisme analogue, par lequel une molécule de solvant prend la place de l'ion Cl-, pour expliquer la voie indépendante de Cl- (c'est-à-dire le terme k1). Cette interprétation permet de prédire que la substitution de H par D catalysée par l'ion Cl- doit être accompagnée d'un échange du coordinat Cl- du complexe contre l'ion Cl” marqué de la solution. Les auteurs décrivent les expériences qu'ils poursuivent pour s'assurer qu'il en est bien ainsi. (author)[es]
La memoria describe un estudio cinético de la reacción de sustitución isotópica trans-HPtCl (PEt3)2 + D2O---» trans-DPtCl (PEt3)2 +HDO (Et = C2H5) en solución acuosa de acetona. El curso de la reacción se siguió por la disminución de la intensidad de la banda infrarroja del enlace Pt-H a 2196 cm-1. Se encontró que los iones D+ yCl- catalizan la reacción de acuerdo con la ley de velocidad aproximada: -d [HPtCl (PEt3)2]/dt = (k1 + k2[Cl-]) [D+] [HPtCl(PEt3)2] where k1 = 4.1 x 10-2 M-1 sec-1 and k2 = 6.0 M-2 sec-1, a 30°C en una mezcla de 75% de acetone y 25% de D2O en volumen. Las velocidades de las vías independientes y dependientes de Cl- son inversamente proporcionales a la concentración del D2O en el disolvente y, además, la dependencia cinética aparente de la segunda vía de la concentración de Cl- excedió del primer orden para las concentraciones bajas de D2O. La vía de intercambio catalizada por Cl- que corresponde al término k2 en la ley de la velocidad, se interpreta recurriendo a un mecanismo que implica una adición reversible de DCl a la capa de coordinación del complejo de platino, para dar como compuesto intermedio un complejo de PtIV hexacoordinado (véase el diagrama en el resumen inglés). Los autores explican la vía independiente del Cl- (es decir, el término k1) invocando un mecanismo análogo, según el cual una molécula del disolvente sustituye al ion Cl-. Esta interpretación predice que la sustitución de H por D catalizada por Cl- debe ir acompañada de un intercambio entre el ligando Cl del complejo y el Cl- marcado presente en la solución. Los autores describen sus experimentos para comprobar la validez de este planteo. (author)[ru]
V doklade opisyvaetsja kineticheskoe izuchenie reakcij izotopnogo zameshhenija (gde Et = S2N5 ), trans-HPtCl (PEt3)2 + D2O---» trans-DPtCl (PEt3)2 +HDO v zhidkom rastvore acetona. Dlja togo, chtoby prosledit' reakciju, ispol'zovalos' sokrashhenie intensivnosti infrakrasnoj polosy Pt-H pri 2196 sm-1. Bylo ustanovleno, chto reakcija kataliziruetsja blagodarja D+ i Sl- v sootvetstvii s zakonom priblizhenija do: -d [HPtCl (PEt3)2]/dt = (k1 + k2[Cl-]) [D+] [HPtCl(PEt3)2] ou k1 = 4.1 x 10-2 M-1 sec-1 et k2 = 6.0 M-2 sec-1 pri 30° i 75%acetona - 25% D2O po obemu. Urovni probega dlja nezavisimogo i zavisimogo SG pokazali obratnuju zavisimost' ot soderzhanija D2O v rastvoritele i v dopolnenie k jetomu javnaja kineticheskaja zavisimost' poslednego probega v SG -koncentracii stala vyshe, chem v koncentracii pervogo porjadka. Obmennyj probeg kataliziruemogo Sl-1 , soglasno uslovijam k2 po zakonu skorosti, objasnjaetsja mehanizmom, svjazannym s reversivnym dobavleniem DCl k koordinirujushhej obolochke platinovogo kompleksa, chtoby dat' geksakoordinirovannyj promezhutochnyj produkt Pt(IV) (sm. shemu v angl. tekste annotacii). Analogichnyj mehanizm, v kotorom rastvorja- shhaja molekula zameshhaet vhodjashhij ion SG , ispol'zuetsja dlja ob'jasnenija puti nezavisimogo SG (t.e. k1). Takoe objasnenie predskazyvaet, chto SG-katalizirujushhee zameshhenie N na D dolzhno soprovozhdat'sja obmenom liganda SG dannogo kompleksa s pomoshh'ju SG- , mechennogo izotopom, v rastvore. Prodolzhajutsja opyty po proverke jetogo mehanizma. (author)Source
International Atomic Energy Agency, Vienna (Austria); 430 p; Oct 1965; p. 191-200; Symposium on Exchange Reactions; Upton, NY (United States); 31 May - 4 Jun 1965; IAEA-SM--64/23; ISSN 0074-1884; 
; 15 refs., 2 tabs., 4 figs.
; 15 refs., 2 tabs., 4 figs.
[en] Malignant fibrous histiocytoma (MFH), arising at the site of a sacral chordoma 8 years after massive radiotherapy, is described. Initially, the patient received 7000 rad to the sacral area and, on recurrence, 5 years later, an additional 4000 rad. Two years later, a sacral mass was noted again. Biopsy then revealed MFH; chest x-ray showed multiple lung metastases. A combination chemotherapy, consisting of cyclophosphamide, vincristine, adriamycin (doxorubicin), and DTIC, resulted in a 6 month partial response. Subsequently, the patient died because of progressive metastatic disease. At autopsy, 8 years after diagnosis, both the sacral lesion and the lung metastases proved to be MFH, and no residual chordoma was found
Journal
Cancer (Philadelphia); ISSN 0008-543X; ; v. 53(12); p. 2661-2662
; v. 53(12); p. 2661-2662
[en] The nonionic detergent, Pluronic L-81 (L-81) has been shown to block the transport of intestinal mucosal triacylglycerol (TG) in chylomicrons. This results in large lipid masses within the enterocyte that are greater in diameter than chylomicrons. On removal of L-81, mucosal TG is rapidly mobilized and appears in the lymph. We questioned whether the blocked TG requires partial or complete hydrolysis before its transport. Rats were infused intraduodenally with [3H]glyceryl, [14C]oleoyl trioleate (TO) and 0.5 mg L-81/h for 8 h, followed by 120 mumol/h linoleate for 18 h. Mesenteric lymph was collected and analyzed for TG content and radioactivity. An HPLC method was developed to separate TG on the basis of its acyl group species. The assumed acyl group composition was confirmed by gas liquid chromatography analysis. TG lymphatic output was low for the first 8 h but increased to 52 mumol/h at the 11th h of infusion (3 h after stopping L-81). 38% of the infused TO was retained in the mucosa after the 8-h infusion. 95% of mucosal TG was TO, 92% of the radioactivity was in TG, and 2.4% of the 14C disintegrations per minute was in fatty acid. HPLC analysis of lymph at 6, 10, 12, and 14.5 h of infusion showed a progressive rise in TG composed of one linoleate and two oleates, to 39%; and in TG composed of two linoleates and one oleate to 20% at 14.5 h of infusion. On a mass basis, however, 80% of the TG acyl groups were oleate. 3H/14C ratios in the various TG acyl group species reflected the decrease in oleate. We conclude that first, unlike liver, most mucosal TG is not hydrolyzed before transport. The mechanism of how the large lipid masses present in mucosal cells after L-81 infusion are converted to the much smaller chylomicrons is unknown. Second, the concomitant infusion of linoleate did not impair lymph TG delivery after L-81 blockade
Journal
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