Search results for "Curve"

1996

Developing an artificial oxygen carrier for use in humans, we polymerize native haemoglobin and myoglobin, using bifunctional, amino group specific cross-linkers, to soluble, so-called hyperpolymers. These polymers, like other polymerized globular proteins, are members of a new class of macromolecues which consist of macromolecular base units. They all have, due to the mechanisms of the chemical reaction, broad distributions of molecular weights. Fractions of hyperpolymers of human haemoglobin were obtained by employing preparative gel-permeation (size-exclusion) chromatography. The calibration curve of analytical gel-permeation chromatography (GPC) for haemoglobin hyperpolymers was determi…

Fatty Acid Aggregates Simulated using Constant pH Molecular Dynamics with a Coarse-Grained Model

2013

Fatty acids are crucial biomolecules, important for lipid metabolism, signaling, models for protocell membranes, soaps, industrial applications, and drug delivery. Oleic acid has complex phase behavior with respect to the protonation state of the carboxylic head group, which depends on the pH of the solution. Oils form at low pHs, vesicles at intermediate pHs, and micelles at high pHs. We use constant pH molecular dynamics with the MARTINI coarse-grained model to investigate oleic acid aggregates at different pH conditions. We determine titration curves for the oleic acid monomers in different aggregates, and observe a shift in the microscopic pKa. In agreement with experimental results, th…

Rotationsdispersion bei monomerem und polymerem L-(–)-Lactid

1965

Bei der kationischen Polymerisation von L-Lactid entsteht ein hochkristallines, isotaktisches Polymeres. Physikalische Eigenschaften des Monomeren und Polymeren werden mitgeteilt. Fur die Rotationsdispersion von L-Lactid in verschiedenen Losungsmitteln gilt die eintermige DRUDE-Gleichung. Das Polymere hat eine Dispersions-Kurve mit einem ersten Extremum bei 275 mμ. Die Dispersionskurve des Poly-L-lactids last sich durch die MOFFITT-YANG-Gleichung beschreiben. Hieraus werden Schlusse auf die Sekundarstruktur des gelosten Polymeren gezogen. In the cationic polymerization of L-lactide a high cristalline isotactic polymer is obtained. Physical properties of monomer and polymer are reported. The…

Kristallisation und schmelzverhalten von fraktionen verzweigten polyethylens, 1. Darstellung und charakterisierung der fraktionen

1983

A branched polyethylene with broad molecular weight distribution was separated into a series of fractions by fractional precipitation from dilute solution. The fractions were characterized by viscometric and density measurements, IR-spectroscopy and calorimetry. The methyl group content and the density turned out as largely constant. Molecular weight effects show up in the melting behaviour. The main range of melting and the end of the melting curve shift to lower temperatures with decreasing molecular weight. Compared to the overall extension of the melting range these shifts are small. One has to conclude that polydispersity gives only a minor contribution to the broadening of the melting…

FIA-Fluorimetric assembly for the determination of noradrenaline hydrochloride by a solid-phase reactor with immobilized hexacyanoferrate(III)

1997

An FIA assembly provided with immobilized hexacyanoferrate(III) is proposed for the fluorimetric determination of noradrenaline hydrochloride. The oxidative reagent is immobilized by means of a strong anion-exchange resin. The FIA manifold is very simple and the calibration graph is linear over the range 0.5–75mgl−1 noradrenaline hydrochloride with an r.s.d of 0.88% (17 replicates) and a sample throughput of 84h−1. Foreign compounds such as NaCl, sucrose, lactose and sodium sulfate caused no significant errors. The procedure is applied to the determination of noradrenaline in a medicinal formulation.

Studies and Research on the Stress – Strain Analyses of the Polyethylene Pipe-Fitting Assemblies Accidentally Subjected to an External Force

2019

Abstract The paper aims at analyzing the behavior of the polyethylene pipe - fitting assembly in the case of accidental stress due to the accidentally occurring external forces (mechanized excavation in the assembly area). The study will identify the necessary computing relationships and the minimum value of the force to which the analyzed assembly breaks, as well as some solutions for avoiding these accidental stresses. A three-dimensional model of the assembly will be made by applying the external forces on three main directions, following the maximum stresses for the same value of the external force. Also, a welding of a polyethylene pipe-fitting assembly will be carried out and it will …

The contribution to poverty persistence of children, adults, and the elderly: some empirical evidences from eleven European countries

2012

This paper aims to communicate a new conceptualization of persistent poverty used to build the class of longitudinal poverty indices by Mendola et al. (2011), and to show how these indices could be helpful in analyzing the characteristics of persistence of poverty in different age groups. The indices are based upon the idea that the longer the sequence of consecutive high poverty gaps is, the worse the situation experienced. An empirical application on European Community Household Panel data compares the contributions of age groups to the overall index in some European countries and allows to identify the strata of population more exposed to poverty persistence.

Strictly convergent algorithm for an elliptic equation with nonlocal and nonlinear boundary conditions

2012

The paper describes a formally strictly convergent algorithm for solving a class of elliptic problems with nonlinear and nonlocal boundary conditions, which arise in modeling of the steady-state conductive-radiative heat transfer processes. The proposed algorithm has two levels of iterations, where inner iterations by means of the damped Newton method solve an appropriate elliptic problem with nonlinear, but local boundary conditions, and outer iterations deal with nonlocal terms in boundary conditions.

Construction stages of cable-stayed bridges with composite deck

2012

A cable-stayed bridge is built by following a construction sequence of different subsequent stages that imply changes of the geometric configuration, restraints and consequently stress and strain patterns. A study is presented about stay stressing sequences in cable-stayed bridges with composite deck for the case of construction made by the cantilever method. Initial cable forces are found through partial elastic schemes of construction stages. Different stay stressing procedures are implemented and a comparison between them is proposed in order to evaluate the differences in terms of deformed shape and internal force distribution of the deck and the pylon. Results can be useful to give pra…

A TOPOLOGICAL STUDY OF PLANAR VECTOR FIELD SINGULARITIES A tribute to Ivar Bendixson

2019

In this paper one extends results of Bendixson [B] and Dumortier [D] about the germs of vector fields with an isolated singularity at the origin of IR 2 , not accumulated by periodic orbits. As new tool, one introduces minimal curves, which are curves surrounding the origin, with a minimal number of contact points with the vector field. Moreover, the arguments are essentially topological, with no use of a desingularization theory, as it is the case in [D]. 2000 Mathematics Subject Classification : 34C05, 34A26.