Two-Dimensional Infrared Spectroscopy of Antiparallel β-Sheet Secondary Structure

We investigate the sensitivity of femtosecond Fourier transform two-dimensional infrared spectroscopy to protein secondary structure with a study of antiparallel β-sheets. The results show that 2D IR spectroscopy is more sensitive to structural differences between proteins than traditional infrared spectroscopy, providing an observable that allows comparison to quantitative models of protein vibrational spectroscopy. 2D IR correlation spectra of the amide I region of poly-L-lysine, concanavalin A, ribonuclease A, and lysozyme show cross-peaks between the IR-active transitions that are characteristic of amide I couplings for polypeptides in antiparallel hydrogen-bonding registry. For poly-L-lysine, the 2D IR spectrum contains the eight-peak structure expected for two dominant vibrations of an extended, ordered antiparallel β-sheet. In the proteins with antiparallel β-sheets, interference effects between the diagonal and cross-peaks arising from the sheets, combined with diagonally elongated resonances from additional amide transitions, lead to a characteristic “Z”-shaped pattern for the amide I region in the 2D IR spectrum. We discuss in detail how the number of strands in the sheet, the local configurational disorder in the sheet, the delocalization of the vibrational excitation, and the angle between transition dipole moments affect the position, splitting, amplitude, and line shape of the cross-peaks and diagonal peaks.

Sprachwissenschaft im III. Reich : ein erster Überblick

Der Themenbereich "Sprachwissenschaft im III. Reich" muß als ungewöhnlich wenig erforscht gelten. Linguisten haben sich daran nahezu überhaupt nicht beteiligt. Die wenigen Kenntnisse, die wir bislang über diesen Bereich haben, verdanken wir vorwiegend Zeitgeschichtsforschern oder Kulturwissenschaftlern, in deren Arbeiten sie allerdings mehr versteckt als veröffentlicht sind. Im Vergleich zu den Kenntnissen, die Sprachwissenschaftler über die Geschichte ihres Fachs im 19. Jahrhundert oder ausländische Forschungsrichtungen wie Strukturalismus und Sprechakttheorie in der Regel haben, ist überdies das Wissen über die Linguistik im Deutschland des III. Reichs auffällig gering

Current Density Functional approach to large quantum dots in intense magnetic fields

Within Current Density Functional Theory, we have studied a quantum dot made of 210 electrons confined in a disk geometry. The ground state of this large dot exhibits some features as a function of the magnetic field (B) that can be attributed in a clear way to the formation of compressible and incompressible states of the system. The orbital and spin angular momenta, the total energy, ionization and electron chemical potentials of the ground state, as well as the frequencies of far-infrared edge modes are calculated as a function of B, and compared with available experimental and theoretical results.Comment: Typeset using Revtex, 17 pages and 13 Postscript figure

Micromechanical study of the load transfer in a polycaprolactone-collagen hybrid scaffold when subjected to unconfined and confined compression

Scaffolds are used in diverse tissue engineering applications as hosts for cell proliferation and extracellular matrix formation. One of the most used tissue engineering materials is collagen, which is well known to be a natural biomaterial, also frequently used as cell substrate, given its natural abundance and intrinsic biocompatibility. This study aims to evaluate how the macroscopic biomechanical stimuli applied on a construct made of polycaprolactone scaffold embedded in a collagen substrate translate into microscopic stimuli at the cell level. Eight poro-hyperelastic finite element models of 3D printed hybrid scaffolds from the same batch were created, along with an equivalent model of the idealized geometry of that scaffold. When applying an 8% confined compression at the macroscopic level, local fluid flow of up to 20 [Formula: see text]m/s and octahedral strain levels mostly under 20% were calculated in the collagen substrate. Conversely unconfined compression induced fluid flow of up to 10 [Formula: see text]m/s and octahedral strain from 10 to 35%. No relevant differences were found amongst the scaffold-specific models. Following the mechanoregulation theory based on Prendergast et al. (J Biomech 30:539-548, 1997. https://doi.org/10.1016/S0021-9290(96)00140-6 ), those results suggest that mainly cartilage or fibrous tissue formation would be expected to occur under unconfined or confined compression, respectively. This in silico study helps to quantify the microscopic stimuli that are present within the collagen substrate and that will affect cell response under in vitro bioreactor mechanical stimulation or even after implantation

A propos du mot Kultur

Weisgerber H. A propos du mot Kultur. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, VI° Série. Tome 6 fascicule 3, 1915. p. 137

A propos des fouilles de Céphalonie.

Weisgerber H. A propos des fouilles de Céphalonie.. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, VI° Série. Tome 2, 1911. pp. 38-39

Les gauchers dans l'armée allemande

Weisgerber H. Les gauchers dans l'armée allemande. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, VI° Série. Tome 4 fascicule 6, 1913. p. 673