Search results for "Secondary"
showing 10 items of 1765 documents
Secondary Structure-Driven Hydrogelation Using Foldable Telechelic Polymer-Peptide Conjugates.
2018
The synthesis of ABA and ABA' triblock polyethylene glycol-and polysarcosine-peptide conjugates is reported. The A/A' peptides are based on phenylalanine(F)-histidine(H) pentapeptide sequences FHFHF, which promote pH-switchable β-sheet self-assembly into nanorods in water. Only parallel β-sheet-driven folding and intermolecular assembly using ABA triblock polymer-peptide conjugates leads to interstrand cross-linking and hydrogelation, highlighting the impact of supramolecular interactions-directed structure formation at the nano- and mesoscopic level.
Calorimetric and Volumetric Investigations of the Effect of the Hydrophobicity of the Surfactant on the Binding between (Ethylene oxide)13-(propylene…
2004
The enthalpy and the volume of transfer (DeltaY(t)) of the unassociated (ethylene oxide)(13)-(propylene oxide)(30)-(ethylene oxide)(13) (L64) from water to the aqueous sodium alkanoate solutions as functions of the surfactant concentrations (m(S)) were determined at 298 K. The surfactants studied are sodium hexanoate, sodium heptanoate, sodium octanoate, sodium undecanoate, and sodium dodecanoate. As a general feature, for the short alkyl chain surfactants, DeltaY(t) describes an S-shaped curve in the range of m(S) analyzed whereas for the more hydrophobic surfactants the DeltaY(t) vs m(S) trends exhibit maxima which appear at ms values very close to the critical micellar concentration in w…
Learning from nature: beta-sheet-mimicking copolymers get organized.
2007
The solution structures formed by coil-coil copolymers arise from the selective solvation of one of the two blocks and have been well described. In most cases in such relatively simple synthetic structures there are no specific attractive forces that can aid the aggregation process. Nature, however, provides plenty of inspiring polymeric architectures that are shaped and ordered hierarchically by noncovalent forces. The high level of structural definition displayed by proteins, for example, is unmatched by synthetic polymers. An emerging area of interest in polymer science tries to combine the best of both worlds, the natural and the synthetic, by conjugating synthetic polymers and beta-she…
Infinite orbit depth and length of Melnikov functions
2019
Abstract In this paper we study polynomial Hamiltonian systems d F = 0 in the plane and their small perturbations: d F + ϵ ω = 0 . The first nonzero Melnikov function M μ = M μ ( F , γ , ω ) of the Poincare map along a loop γ of d F = 0 is given by an iterated integral [3] . In [7] , we bounded the length of the iterated integral M μ by a geometric number k = k ( F , γ ) which we call orbit depth. We conjectured that the bound is optimal. Here, we give a simple example of a Hamiltonian system F and its orbit γ having infinite orbit depth. If our conjecture is true, for this example there should exist deformations d F + ϵ ω with arbitrary high length first nonzero Melnikov function M μ along…
COPD in elderly patients – an analysis of the DACCORD observational study
2018
Introduction: In elderly patients COPD is frequently complicated by the presence of several comorbidities and the many non-COPD-related medications prescribed to treat these conditions. This analysis aims to characterize COPD patients above the age of 75 in a real-world cohort in Germany. Methods: DACCORD is a prospective, non-interventional study collecting data from COPD patients treated in primary and secondary care. Prior to study entry, patients either initiated or changed COPD maintenance medication. Moderate/severe exacerbations, COPD-medication and non-COPD medication were documented at baseline and every 3 months. Comorbidities were documented at baseline. Results: Baseline charact…
Dynamic Animal Populations in Managed Forests: Species Ecological Requirements and Sustainable Harvesting
2015
Forest management has altered forested environments and provoked stress to many natural habitats and biodiversity. The goal of biodiversity management is the long-term persistence of populations in human-modified environments. We demonstrate a spatio-temporal modeling approach to address the relationship between various management objectives and population persistence in the long-term in a commercial forest landscape. We used the flying squirrel (Pteromys volans), the three-toed woodpecker (Picoides tridactylus) and the long-tailed tit (Aegithalos caudatus) as example species. They are all forest species but they have distinctly different habitat requirements. In the model, forest growth, f…
Impact of secondary succession in abandoned fields on some properties of acidic sandy soils
2020
Abstract Abandonment of agricultural lands in recent decades is occurring mainly in Europe, North America and Oceania, and changing the fate of landscapes as the ecosystem recovers during fallow stage. The objective of this study was to find the impact of secondary succession in abandoned fields on some parameters of acidic sandy soils in the Borská nížina lowland (southwestern Slovakia). We investigated soil chemical (pH and soil organic carbon content), hydrophysical (water sorptivity, and hydraulic conductivity), and water repellency (water drop penetration time, water repellency cessation time, repellency index, and modified repellency index) parameters, as well as the ethanol sorptivit…
La formación inicial del profesorado de Educación Secundaria: una mirada comparativa en la Unión Europea
2011
El artículo comienza exponiendo los modelos que se han utilizado en la formación del profesorado de Secundaria y sus características, para adentrarse en el modelo de formación español y analizarlo a la luz de esos paradigmas formativos. Posteriormente se describe el cambio realizado en España con la introducción del Máster de Formación del Profesorado de Secundaria, estudiando el efecto de los cambios y las dificultades habidas en su introducción. En la segunda parte se analiza la formación de los docentes europeos desde variables como el modelo formativo, los salarios, el tiempo de trabajo o la jubilación, y se establece una serie de conclusiones finales sobre la realidad y la prospectiva …
Emerging Tiger? The Paradoxes of the Philippine Economy
2017
The Republic of the Philippines is an exception in the East and Southeast Asia realm. One of the richest countries of the region at the end of World War II, its rankings have slipped, and its growth rates have been weak for several decades. We examine the main causes of the mediocre economic performance of the country since the 1950s. Many analysts have pointed out an excessive bureaucracy, high levels of corruption and the lack of industrial investment in a country dominated by landed interests. After the high debt incurred during the Marcos administration, Philippine leaders have made every effort to improve the debt situation, choosing to pay back loans, but under investing in infrastruc…
On the influence of curvature and torsion on turbulence in helically coiled pipes
2014
Turbulent flow and heat transfer in helically coiled pipes at Ret=400 was investigated by DNS using finite volume grids with up to 2.36×10^7 nodes. Two curvatures (0.1 and 0.3) and two torsions (0 and 0.3) were considered. The flow was fully developed hydrodynamically and thermally. The central discretization scheme was adopted for diffusion and advection terms, and the second order backward Euler scheme for time advancement. The grid spacing in wall units was ~3 radially, 7.5 circumferentially and 20 axially. The time step was equal to one viscous wall unit and simulations were typically protracted for 8000 time steps, the last 4000 of which were used to compute statistics. The results sho…