Search results for "circular"
showing 10 items of 856 documents
A Macroeconomic Analysis of Regional Migration in Finland, 1975-95
1999
This study analyzes regional migration in the 85 Finnish subregions during the period 1975-95 using data on net in-migration rates. Both cross-section and panel data methods are employed. The regression analysis reveals that the direction of net in-migration flows can be explained by a set of regionally differing characteristics. Unemployment rates, tax rates, and the share of primary production affect net in-migration negatively, whereas the share of higher education and the growth of regional incomes have a positive effect. This indicates that regional disparities may not be alleviated by migration, but there is some evidence for a cumulative causation growth pattern induced by net in-mig…
Life Cycle Assessment of repurposed electric vehicle batteries: an adapted method based on modelling energy flows
2018
Abstract After their first use in electric vehicles (EVs), the residual capacity of traction batteries can make them valuable in other applications. Although reusing EV batteries remains an undeveloped market, second-use applications of EV batteries are in line with circular economy principles and the waste management hierarchy. Although substantial environmental benefits are expected from reusing traction batteries, further efforts are needed in data collection, modelling the life-cycle stages and calculating impact indicators to propose a harmonized and adapted life-cycle assessment (LCA) method. To properly assess the environmental benefits and drawbacks of using repurposed EV batteries …
C2-Symmetric Ferrocene-Bis(ureido)peptides : Synthesis, Conformation and Solid-State Structure
2009
The extension of peptide derivatives of ferrocene-1,1'-dicarboxylic acid by formal insertion of NH units between ferrocene and peptide strands results in ferrocene-bis(ureido)-peptides. Experimentally, alanine and dialanine methyl esters were attached to the 1- and 1'-position of 1,1'-diiso-cyanoferrocene to give the corresponding bis(ureido)peptide derivatives 3 and 4. The conformation of 3 has been determined in the solid state by X-ray crystallography. In solution the preferred conformation of 3 and 4 has been elucidated by NMR, IR and CD spectroscopy in concert with DFT calculations. The secondary structure of ferrocene―bis(ureido)peptides 3 and 4 is determined by double bifurcated intr…
Low-Temperature Optical Spectroscopy of Native and Azide-Reacted Bovine Cu,Zn Superoxide Dismutase. A Structural Dynamics Study
1994
The optical absorption spectra of native and N(3-)-reacted Cu,Zn superoxide dismutase (SOD) has been studied in the temperature range 300-10 K. The broad d-d bands observed in the room temperature spectrum, centered at 14,700 cm-1 (native enzyme) and at 15,550 cm-1 (N(3-)-reacted enzyme), are clearly split at low temperature into two bands each, centered at 12,835 and 14,844 cm-1 and at 14,418 and 16,300 cm-1, respectively. The thermal behavior of the 23,720 cm-1 band present in the spectrum of the native enzyme indicates that this band belongs to the His61-->Cu(II) ligand to metal charge transfer transition. Analysis of the zeroth, first, and second moments of the various bands as a functi…
Pigment-pigment interactions and secondary structure of reconstituted algal chlorophyll a/b-binding light-harvesting complexes of Chlorella fusca wit…
1995
Earlier we have shown by in vitro reconstitution experiments that the pigment composition of the chlorophyll alb-binding light-harvesting complex of the green alga Chlorella fusca could be altered in a relatively broad range (Meyer and Wilhelm 1993). In this study we used these reconstituted complexes of different pigment loading to analyze the excitonic interactions between the pigment molecules and the secondary structure by means of circular dichroism spectra in the visible and the far UV spectral regions, respectively. We found that, in contrast to the expectations, the pigment composition and pigment content hardly affected the circular dichroism spectra in the visible spectral region.…
Superchiral Pd 3 L 6 Coordination Complex and Its Reversible Structural Conversion into Pd 3 L 3 Cl 6 Metallocycles
2015
Large, non-symmetrical, inherently chiral bispyridyl ligand L derived from natural ursodeoxycholic bile acid was used for square-planar coordination of tetravalent Pd(II) , yielding the cationic single enantiomer of superchiral coordination complex 1 Pd3 L6 containing 60 well-defined chiral centers in its flower-like structure. Complex 1 can readily be transformed by addition of chloride into a smaller enantiomerically pure cyclic trimer 2 Pd3 L3 Cl6 containing 30 chiral centers. This transformation is reversible and can be restored by the addition of silver cations. Furthermore, a mixture of two constitutional isomers of trimer, 2 and 2', and dimer, 3 and 3', can be obtained directly from …
Stabilization of an ?-helical conformation in an isolated hexapeptide inhibitor of calmodulin
2001
The conformational properties of two hexapeptides, Ac-LWRILW-NH(2) and its D-amino acid counterpart Ac-lwrilw-NH(2), identified as calmodulin inhibitors using mixture-based synthetic combinatorial library approaches, have been characterised by NMR and CD spectroscopy. The peptides fold into an alpha-helical conformation in aqueous solution. The observed short- and medium-range nuclear Overhauser effects were consistent with the formation of an alpha-helical structure and a reasonably well-defined set of structures was obtained by using restraints from the NMR data in simulated annealing calculations. Analysis of glycine-substitution analogues demonstrated that all the amino acids that make …
Hierarchical structure formation of cylindrical brush polymer-surfactant complexes.
2009
The complex formation of cylindrical brush polymers with poly(l-lysine) side chains (PLL) and sodium dodecyl sulfate (SDS) can induce a helical conformation of the cylindrical brush polymer in aqueous solution (Gunari, N.; Cong, Y.; Zhang, B.; Fischer, K.; Janshoff, A.; Schmidt, M. Macromol. Rapid Commun. 2008, 29, 821-825). Herein, we have systematically investigated the influence of surfactant, salt, and pH on the supramolecular structure formation. The cylindrical brush polymers and their complexes with surfactants were directly visualized by atomic force microscopy in air and in aqueous solution. The alkyl chain length (measured by the carbon number, n) of the surfactant plays a key rol…
Flexible Chirality in Self-Assembled N-Annulated Perylenedicarboxamides.
2017
N-annulated perylenedicarboxamides 1-3 form supramolecular polymers with a strong tendency to aggregate. The bundles of fibers formed generate a spontaneous anisotropy that conditions the chiroptical features of the described molecules in solution; a strong linear dichroism effect accompanies the circular dichroism (CD) outcome. There is no influence of the point chirality existing at the side chains of 1 and 2, and these molecules present the same chiroptical features as achiral 3. Mechanical rotary stirring increases the CD response and the sign of the dichroic signal changes with the stirring direction. Theoretical calculations indicate that the self-assembly of 1-3 in helical columnar s…
Stereochemistry of terpene derivatives. Part 4:☆ Fragrant terpenoid derivatives with an unsaturated gem-dimethylbicyclo[3.1.0]hexane system
2005
Abstract Starting from (+)-3-carene 1 several chiral fragrant compounds with the bicyclo[3.1.0]hexane system 4–6 and 10–20 were synthesized. These compounds are structural analogues of naturally occurring fragrant compounds, such as ionones and damascones, and possess either an endo- or an exo-cyclic double bond in the bicyclo[3.1.0]hexane moiety. The absolute configuration of selected products was confirmed by X-ray crystallography and circular dichroism analysis.