Novel Approach to the Analysis of Broadband Dielectric Spectra

Schäfer, Hartmut; Sternin, Edward; Stannarius, Ralf; Arndt, M. B.; Kremer, Friedrich

doi:10.1103/physrevlett.76.2177

Cited by 124 publications

(94 citation statements)

References 13 publications

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“…In general, the ( , ) angles will not have a fixed value but are given by a PDF P( , ). Using a regulatory data analysis (18,37), ''model-free'' in the functional shape of P( , ), we can identify the secondary structure elements in silk of the spider N. edulis at the alanine and glycine residues, which make up almost 70% of the primary sequence. Note that we selectively determine the angles for Ala-Ala and Gly-Gly pairs in this way.…”

Section: Resultsmentioning

confidence: 99%

The molecular structure of spider dragline silk: Folding and orientation of the protein backbone

Beek

Heß

Vollrath

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

475

607

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The design principles of spider dragline silk, nature's highperformance fiber, are still largely unknown, in particular for the noncrystalline glycine-rich domains, which form the bulk of the material. Here we apply two-dimensional solid-state NMR to determine the distribution of the backbone torsion angles ( , ) as well as the orientation of the polypeptide backbone toward the fiber at both the glycine and alanine residues. Instead of an ''amorphous matrix,'' suggested earlier for the glycine-rich domains, these new data indicate that all domains in dragline silk have a preferred secondary structure and are strongly oriented, with the chains predominantly parallel to the fiber. As proposed previously, the alanine residues are predominantly found in a ␤ sheet conformation. The glycine residues are partly incorporated into the ␤ sheets and otherwise form helical structures with an approximate 3-fold symmetry.

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Section: Resultsmentioning

confidence: 99%

The molecular structure of spider dragline silk: Folding and orientation of the protein backbone

Beek

Heß

Vollrath

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

475

607

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“…A detailed description can be found in (Banys et al, 2002). We assume that the complex dielectric spectrum * (ν) can be represented as a superposition of independent individual Debye-type relaxation processes (Schafer et al, 1996;Kim et al, 2000;Pelster et al, 1998) …”

Section: Inhomogeneous Ferrielectricsmentioning

confidence: 99%

Phase Transitions in Layered Semiconductor - Ferroelectrics

Džiaugys¹,

Banys²,

Samulionis³

et al. 2011

Ferroelectrics - Characterization and Modeling

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“…The fit of ) , ( " T f ε with eq. 4 is an inverse and ill-posed problem [15,16] so that no unique solution for ) ( i E G ∆ can be extracted. However, a "guessed" ) ( i E G ∆ function can be input into the minimization procedure based on some assumptions derived from the knowledge of the crystallographic structure of the studied zeolites.…”

Section: Camentioning

confidence: 99%

Insights into cation exchange selectivity of a natural clinoptilolite by means of dielectric relaxation spectroscopy

et al. 2011

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To cite this version:Gerardo Rodriguez-Fuentees, Sabine Devautour-Vinot, Sekou Diaby, François Henn. Insights into cation exchange selectivity of a natural clinoptilolite by means of dielectric relaxation spectroscopy. Phys. Chem. Minerals, 2011, 38 (xx) ABSTRACT.Purified natural clinoptilolite from the Tasajeras deposit, Cuba, and some of its metal exchanged forms are studied, at the dehydrated state, by means of Dielectric Relaxation Spectroscopy (DRS) using two different modus operandi: Complex Impedance Spectroscopy and Dielectric Dynamic Thermal Analysis. Data analysis yields the determination of the extra-framework cation (EFC) population into the various possible crystallographic sites of the zeolitic framework as well as of the activation energy characterizing the localized hopping mechanism of EFC. First, it is shown that the DRS responses obtained here match well with the previous reported data which were previously localized EFCs in positions close to M1 and M2 sites when the clinoptilolite is modified to almost homoionic form. From this outcome, it can be concluded that all EFCs are in the same crystallographic situation regarding solvation or, in other terms, that no steric effect can be taken into account to explain cationic selectivity. Second, based on the assumption that the activation energy for EFC hopping is directly connected to the EFC/framework interaction and on simple thermodynamics consideration, we show this interaction does not govern the EFC 2 exchange reaction. So, it is emphasized that EFC/H 2 O interaction is the key factor for cation exchange selectivity.

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Novel Approach to the Analysis of Broadband Dielectric Spectra

Cited by 124 publications

References 13 publications

The molecular structure of spider dragline silk: Folding and orientation of the protein backbone

The molecular structure of spider dragline silk: Folding and orientation of the protein backbone

Phase Transitions in Layered Semiconductor - Ferroelectrics

Insights into cation exchange selectivity of a natural clinoptilolite by means of dielectric relaxation spectroscopy

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