SummaryThe method of semiempiric-atomistic calculations is applied to a polydiene. For this purpose a Coulomb term has to be added to a potential set used successfully for polyolefines. All stable 4 * p/q helices of poly(trans-l,4-hutadiene) are calculated. This yields a conformation for the low temperature phase which is in agreement with X-ray data in the literature. Chain conformations are proposed for the high temperature phase carefully considering the energies (determined in the single chain approximation) and the packing properties.Experimentelly, the enthalpy and entropy differences between the phases, calculated only intramolecularly, are determined by high pressure dilatometry and calorimetry. A commercial material is investigated in the full pressure range up to 3 kbar; for low pressure dilatometry and calorimetry a purely trans polymer, initially in extended chain conformation, is used. Experimental data are compared with calculated values and discrepancies are discussed. ZusammenfassungDie Methode der semiempirisch-atomistischen Rechnung wird auf ein Polydien angewendet. Dazu wird ein bei Polyolefinen bew~ihrter Potentialsatz um einen Coulombterm erweitert. Berechnet werden alle stabilen 4 * p/q Helices des Poly-trans-l,4-bntadiens, und es ergibt sich eine Konformation fiir die Tieftemperaturphase, die rnit R6nt-gendaten in der Literatur iibereinstimmt. Fiir die Hochtemperaturphase werden Kettenkonformationen vorgeschlagen, bei denen die in der Einzelkettenniiherung bestimmte Energie und die Packung berficksichtigt wird.Die Enthalpie-und Entropieunterschiede zwischen beiden Phasen, die bisher nut intramolekular berechnet sind, werden experimentell mit den Methoden der Hochdruckdilatometrie und der Kalorimetrie bestimmt. Dabei wird im Hochdruckbereich his 3 kbar ein handelsiibliches Material gemessen, im Niederdruckbereich und kalorimetrisch aher ein reines trans-Polymeres, das anfangs gestrecktkettig vorliegt. Die experimentellen Werte werden mit den berechneten verglichen, und ihre Unterschiede werden diskutiert.
The Effect of Different Caloric Supplements (Glucose, Fructose, Triglycerides) on the Utilisation of Parenterally Administered Amino Acids Summary. In 6 healthy vohmteers glucose solutions, laevulose solutions or triglyceride emulsions were infused simultaneously with an amino acid solution prepared by the authors. The nitrogen intake amounted to 160 mg/kg, the total calorie supply was 26 ealories/kg body weight. The concentration of 17 plasma amino acids was determined before, at the end and 1--3 hrs after the infusion. The urinary amino acid excretion was measured during two collection periods.During the infusion the plasma levels of all amino acids increased. 1--3 hrs after terminating the infusion the amino acids returned to or below the fasting values. The alteration in the pattern of the plasma amino acids was comparable to the changes we observed after oral intake of the same amount of protein of high biological value. Considerable differences have been observed between persons infused with triglycerides or glucose on the one hand and with laevulose on the other. Simultaneous infusions of amino acids with triglycerides lead to the smallest increase of the plasma amino acids. The highest increase was observed when laevulose was infused. The aminoaciduria was negligible in all persons, but it corresponded with the total increase of plasma amino nitrogen.Individual amino acids showed similar increases. Therefore the amino acid pattern of the plasma was not altered significantly. The changes were much less pronounced than in previous infusion experiments with other amino acid solutions. The differences between our 3 series in this respect were small and of short duration. The smallest changes in plasma amino acids can be expected by infusion of an amino acid solution containing essential and non-essential amino acids in a pattern used in this study and given simultaneously with adequate calories supplied as glucose together with triglyeerides, a combination which conforms best with the composition of a natural meal.
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