Search results for "rotation"
showing 10 items of 935 documents
Über die polymeranaloge bromierung von naturkautschuk und einige lösungseigensch aften des bromkautschuks. Über die molekularen konstanten von naturk…
1961
Naturkautschuk last sich in verdunnter Losung in Cyclohexan bromieren, wobei das Molekulargewicht entsprechend dem Bromgehalt zunimmt (polymeranaloge Umsetzung). Fur Bromkautschuk steigenden Bromgehalts wird Cyclohexan ein zunehmend schlechteres Losungsmittel, was sich in einer Abnahme des 2. osmotischen Virialkoeffizienten und einer Kontraktion des Molekulknauels zeigt. Dieses Ergebnis wird in quantitativer Ubereinstimmung durch Viskositats- und Lichtstreuungsmessungen erhalten. Cyclohexanlosungen von Bromkautschuk mit 43% Brom haben bei Zimmertemperatur einen Θ-Punkt. In diesem Zustand ist der Knauel 1,74mal groser als bei freier Drehbarkeit, in ziemlich guter Ubereinstimmung mit dem an a…
NMR-Spektroskopie an Heterocyclen, 2. Mitt. Kernalkylierte und isomere Nicethamidderivate
1976
Von kernalkylierten und isomeren Nicethamidderivaten wurden die 13C-NMR-Shiftwerte ermittelt und mit Hilfe der 1H-NMR-Spektroskopie die Energiebarriere bei der gehinderten Rotation der Amidgruppe bestimmt. Ringalkylated and Isomeric Nicethamide Derivatives The 13C-n.m.r. shifts were determined for ringalkylated and isomeric nicethamide derivatives and the energy barrier of the hindered rotation of the amide group was evaluated by means of 1H-n.m.r.
Stufenweise darstellung eines cycloheptamers aus p-kresol, 4-tert-butylphenol und formaldehyd. Vergleich mit einem phenolischen, heptanuklearen kette…
1980
A phenolic cycloheptamer (11) and an analogous chain oligomer (10) with nearly the same structure were gained by stepwise syntheses. The cycloheptamer has a higher melting point and a better solubility in chloroform. In contrast to the chain oligomer his infrared spectrum indicates a stronger association of the hydroxyl groups which is not influenced by the solvent. The mass spectra announce a preferred statistical cleavage along the chain of compound 10 and a great stability of the ring of 11 which preferentially loses his substituents. The 1H NMR spectra confirm the constitutions of the chain (10) and ring compound (11). The cycloheptamer is distinguished by a ring inversion or a pseudoro…
Schrittweise synthesen und eigenschaften einiger cyclopentamerer aus methylenverbrückten (5-alkyl-2-hydroxy-1,3-phenylen)-bausteinen
1981
Three cyclopentamers (2a–c) and a chainlike pentanuclear oligomer (3a) were prepared by stepwise syntheses. The molecules of the cyclic compounds with 20 links contain o,o′-methylene bridged 2-hydroxy-5-methyl-1,3-phenylene or 2-hydroxy-5-tert-butyl-1,3-phenylene units in a strictly defined manner. The properties of the cyclic pentamer 2a and the chainlike pentanuclear oligomer 3a were compared. They differ by their solubilities, melting points, IR and 1H NMR spectra (pseudorotation) and fragmentation behaviour shown by their mass spectra. The pseudorotation of the cyclic compounds were quantitatively studied.
Performance Test of Various Teeth Diameter of Cylinder Type Sago Rasping Machine
2021
Traditional method of sago starch extraction was a time and labor intensive process. The most laborious stage is pith disintegration which is done by using hammer-like tools called pounder. However, the use of rasping machine to disintegrate the pith is saving time and energy significantly. The objective of this study was to investigate the effect of teeth diameter and cylinder rotation speed on performance of cylinder type sago rasping machine. In the experiment, four variations of teeth diameter i.e. 3mm, 4 mm, 5 mm and 6 mm, and three levels of cylinder rotation speed i.e. 1500 rpm, 2000 rpm and 2500 rpm were examined. Results showed that both teeth diameter and cylinder rotation speed s…
Absolute Configuration Determination of 2,3-Dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles Using Chiroptical Methods at Different Wavelengths
2016
A correlation between the absolute configuration and chiroptical properties of nonracemic 1,6,7-trisubstituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles was studied. A series of 16 novel representatives were prepared by Cu-catalyzed [3 + 2] cycloadditions of racemic (Z)-2-benzylidene-5-oxopyrazolidin-2-ium-1-ides to tert-butyl (S)-(3-oxopent-4-yn-2-yl)carbamate, and their structures were determined by NMR, VCD, ECD, and X-ray diffraction. A clear correlation between the sign of specific rotation and configuration at position C(1) allows for easy determination of the absolute configuration of 1,6,7-trisubstituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles by ECD and NMR. While VCD, requirin…
ALIGNEMENT UNI ET TRIDIMENSIONNEL DE MOLÉCULES PAR IMPULSION LASER FEMTOSECONDE
2007
This thesis is devoted to the study of the alignment of linear and asymmetric top molecules generated by an intense laser pulse. In the case of short pulses with respect to molecular rotation, periodic alignment appears in field-free conditions after the extinction of the field. We study theoretically and experimentally the effects of intensity, temperature and polarization of the electric field on produced alignment. If the field is linearly polarized, the interaction leads to the alignment of the most polarizable axis of the molecule. If the field is elliptically polarized, the pulse can generate a simultaneous alignment of the three principal axes of inertia of an asymmetric top molecule…
Crop rotation, nitrogen fertilization and genotype effects on durum wheat productive characteristics
2004
A field trial was performed in 2000/01 and 2001/02 in the experimental farm “Sparacia” (Cammarata – AG – Sicily) in order to evaluate the qualitative and quantitative response of four varieties of durum wheat when grown after a legume crop (field pea) or in rotation with itself and when submitted to different N-fertilization levels: no fertilization (N0, control), 60 kg ha-1 (N 60, rate advised by the EC n. 2078/92 for the Sicilian territory) and 120 kg ha-1 (N 120, fertilization rate commonly used under the “traditional” cropping technique). In the first trial year, the fertilized trial expressed a better yield performance than the control, but in 2001/02, characterized by severe and prolo…
Microbial biomass carbon dynamics in a long-term tillage and crop rotation experiment under semiarid Mediterranean conditions
2015
Microbial biomass carbon (MBC) of soil is an important ecological indicator of nutrient cycling and soil fertility. In addition, it responds to the changes of soil fertility more rapidly than soil organic matter. The aim of the present work was to evaluate the effect of a long-term implementation of a conservative soil management strategy (No Tillage [NT]) compared to the inversion tillage (conventional tillage [CT]) on the soil MBC in a range of crops - continuous durum wheat (WW), wheat after fababean (FW) and faba bean after wheat (WF). MBC of NT plots was higher than CT. In addition, the content of MBC varied with sampling time during the growing season; this variation did not show a co…
Reti sismiche urbane per monitoraggio sismico monitoraggio strutturale ed allerta precoce
2021
In questa tesi, viene effettuato un analisi preliminare in cui si mette in evidenza come l'italia sia un paese a rischio sismico, poichè possiede molti centri storici con strutture non progettate per eventi sismici di media entità. Si è prestato molta attenzione su quante vite umane vengono salvate dopo un terremoto catastrofico. L'analisi fa emergere come, è importante essere tempestivi nell'estrarre le persone rimaste sotto le macerie, poichè la percentuale di persone estratte vive si mantiene alta solo entro le 48 ore dall'evento. Dopo 96 ore questa percentule si attesta a 0. In eventi passati spesso i soccorsi sono arrivati con giorni di ritardo nelle zone più devastate. L'obbiettivo ch…