Search results for "Osmometer"

Complexes of organometallic compounds XXVIII. The solution chemistry of bis(acetylacetone)ethylenediimine adducts of organotin(IV) halides

1971

Abstract The nature of methanol solutions of a series of bis(acetylacetone)ethylenediimine adducts of organotin(IV) halides has been studied by electronic and PMR spectroscopy and by osmometry and conductivity. Effectively complete dissociation to the free ligand and solvated organotin(IV) halide moieties is inferred.

Physical forces in blister formation. The role of colloid osmotic pressure and of total osmolality in fluid migration into the rising blister.

1978

The physical forces operative in the fluid migration from the interstitial spaces into the blister cleft have not been directly measured until now. The colloid osmotic pressure and the total osmolality were determined in suction blister fluid after mild suction blister production by a modified “Dermovac” and in blister fluid of patients with dermatitis herpetiformis, bullous allergic contact dermatitis and pemphigus vulgaris and in the sera of healthy persons. The colloid osmotic pressure was measured by means of a recently developed osmometer with a semipermeable membrane between 2 chambers, one of them filled with Ringer solution, the other with the blister fluid or serum sample. The nega…

Zur kinetik des einstellvorganges im osmometer. II. Theoretische grundlagen

1961

Es werden Gleichungen fur den zeitlichen Verlauf der Osmometereinstellung fur den Fall abgeleitet, das der geloste Stoff wesentlich langsamer als das Losungsmittel (LM) durch die Membran tritt. Der Verlauf ist abhangig von der Einstellkonstante ζ1 und der Durchtrittskonstante ζ2. Diese einzeln durch Experimente bestimmbaren Konstanten hangen von den Permeationskonstanten Z1 und Z2 der Membran fur das Losungsmittel und die geloste Substanz und von den Osmometerdimensionen ab. Bei der Ableitung wird die Nichtidealitat der Losung, der Balloneffekt und die durch die Verschiebung des Losungsmittels bedingte Konzentrationsanderung berucksichtigt. Wenn in beiden Osmometerkammern die Durchmischung …

1980

Molecular weights of Trogamid T® were determined by ultracentrifugation, light-scattering, osmometry and viscometry, molecular weight distributions by gel permeation chromatography (GPC) and five different fractionation methods. The separation efficiency of GPC with N,N-dimethylformamide as solvent was tested with three different types of gels, crosslinked polystyrene, porous glass and crosslinked poly(vinyl acetate), the last one yielding the best results. Solution fractionations show better results than precipitation methods. All fractionations gave far too small apparent non-uniformities. After correction according to the non-uniformities of the fractions the results corresponded to thos…

Zur kinetik des einstellvorganges im osmometer. III. Versuche mit fraktionen definierten molekulargewichts an ultracellafiltern verschiedener durchlä…

1961

Die theoretisch fur ein ideales Osmometer abgeleiteten Gleichungen fur den Einstellverlauf werden an einem Osmometer nach MEYERHOFF mit Ultracellafiltern an Fraktionen von Polymethylmethacrylat im Molekulargewichtsbereich von 4000 bis 40 000 gepruft. Es zeigt sich, das die Nichtidealitat des Osmometers eine erhebliche Modifikation hervorruft, als deren Ursache die unvollkommene Durchmischung in den Osmometerkammern anzusehen ist. Dadurch ist der effektive osmotische Druck an der Membran niedriger als der mittlere osmotische Druck in den Kammern. Es wird gezeigt, das man auch unter diesen Umstanden die Einstellkonstante ζ1 fur das Losungsmittel und die Durchtrittskonstante ζ2 fur das Geloste…

1996

An iterative, approximative procedure is presented, to calibrate the determination of molar masses of polymers with gel-permeation chromatography, additionally using viscometry, and transformations, according to Benoit's concept of universal calibration, even if only polymers with broad molar mass distribution are available. The calculated (intermediate) values of the average molar masses from each step of iteration converge to final values. With at least two fractions of the polymers to be analyzed, and with measured intrinsic viscosities of the fractions, a calibration curve of gel-permeation chromatography and Mark-Houwink's constants can be determined. Assumptions for the use of the cal…

ChemInform Abstract: COMPLEXES OF ORGANOMETALLIC COMPOUNDS PART 42, SPECTROSCOPIC STUDIES OF N,N′-ETHYLENEBIS(ACETYLACETONEIMINE) AND N,N′-ETHYLENEBI…

1975

Abstract The nature of the 1 1 adducts formed from the ligands N,N′-ethylenebis(acetylacetonemine) and N,N′-ethylenebis(salicylideneimine) with Ph2PbCl2 and PhTlCl2 was investigated in the solid state and in methanol solution by IR, electronic and PMR spectroscopy, and by osmometry and conductivity. The adducts exist only in the solid state and dissociate fully into the parent compounds in solution. Polymeric structures are proposed for the solids, in which bis-monodentate ligands bridge the organometallic moieties.

Osmolality of various viscoelastic substances: comparative study.

2000

Abstract Purpose To determine the osmolality of various viscoelastic substances. Setting Department of Ophthalmology, Johannes Gutenberg-University, Mainz, and Institute for Medical Device Testing, Memmingen, Germany. Methods The analysis was carried out according to the European Pharmacopoeia by means of a calibrated osmometer using the freezing-point depression method. Each syringe was analyzed as a duplicate analysis. Results Mean osmolalities (mOsmol/kg) of the sodium hyaluronate viscoelastic substances were Allervisc® 299; Allervisc® Plus 307; Amvisc® Plus 335; AMO Vitrax® 284; Biolon® 279; Dispasan® 311; Dispasan® Plus 314; Healon® 295; Healon GV® 312; Healon®5 322; HYA-Ophtal® 376; M…