Voltammetric Studies of the Electrochemical and Interfacial Behaviour of DNA at Charged Interfaces

A survey of the essentials of the experimental evidence assembled in systematic extended voltammetric studies of denatured and native DNA is rpresented. Applying an advanced verision of single triangle sveep voltammetry at the HMDE and by supporting measurements with various other polarographic methods, :such as phase sensitive a.c.-voltammetry, the adsrnrption parameters, the sequence of i!ll!terfacial events as a function of adsorption time and adso1rption potentia·l arid the kinetics of the electrode process have been elucidated. While for pH~ 7 in adsorbed DNA the adenine and cytosime moieties are immediately reducible in a totally irreversible electrode reaction Y•ielding a strongly adsorbed compact film of reduction products, they have to become accessible to electron and proton transfer in adsorbed native DNA in a sequence of prior deconformation steps involving opening and unwinding of the double helix under the co.nstraint exerted by the adsorption interactions and by the interfacial electric field. In a fundamental biophysicochemical sense the results enable general conclusions on the behaviour of DNA when it interacts with charged interfaces d.m the living cell

A phase field model for the electromigration of intergranular voids

Published versio

PARAMETRIC APPROXIMATION OF WILLMORE FLOW AND RELATED GEOMETRIC EVOLUTION EQUATIONS

Accepted versio

A stable numerical method for the dynamics of fluidic membranes

We develop a finite element scheme to approximate the dynamics of two and three dimensional fluidic membranes in Navier–Stokes flow. Local inextensibility of the membrane is ensured by solving a tangential Navier–Stokes equation, taking surface viscosity effects of Boussinesq–Scriven type into account. In our approach the bulk and surface degrees of freedom are discretized independently, which leads to an unfitted finite element approximation of the underlying free boundary problem. Bending elastic forces resulting from an elastic membrane energy are discretized using an approximation introduced by Dziuk (2008). The obtained numerical scheme can be shown to be stable and to have good mesh properties. Finally, the evolution of membrane shapes is studied numerically in different flow situations in two and three space dimensions. The numerical results demonstrate the robustness of the method, and it is observed that the conservation properties are fulfilled to a high precision

Parametric approximation of surface clusters driven by isotropic and anisotropic surface energies

Published versio

A multiphase Cahn--Hilliard--Darcy model for tumour growth with necrosis

We derive a Cahn–Hilliard–Darcy model to describe multiphase tumour growth taking interactions with multiple chemical species into account as well as the simultaneous occurrence of proliferating, quiescent and necrotic regions. A multitude of phenomena such as nutrient diffusion and consumption, angiogenesis, hypoxia, blood vessel growth, and inhibition by toxic agents, which are released for example by the necrotic cells, are included. A new feature of the modelling approach is that a volume-averaged velocity is used, which dramatically simplifies the resulting equations. With the help of formally matched asymptotic analysis we develop new sharp interface models. Finite element numerical computations are performed and in particular the effects of necrosis on tumour growth are investigated numerically. In particular, for certain modelling choices, we obtain some form of focal and patchy necrotic growth that have been observed in experiments

Voltammetric Studies of the Electrochemical and Interfacial Behaviour of DNA at Charged Interfaces

A survey of the essentials of the experimental evidence assembled in systematic extended voltammetric studies of denatured and native DNA is rpresented. Applying an advanced verision of single triangle sveep voltammetry at the HMDE and by supporting measurements with various other polarographic methods, :such as phase sensitive a.c.-voltammetry, the adsrnrption parameters, the sequence of i!ll!terfacial events as a function of adsorption time and adso1rption potentia·l arid the kinetics of the electrode process have been elucidated. While for pH~ 7 in adsorbed DNA the adenine and cytosime moieties are immediately reducible in a totally irreversible electrode reaction Y•ielding a strongly adsorbed compact film of reduction products, they have to become accessible to electron and proton transfer in adsorbed native DNA in a sequence of prior deconformation steps involving opening and unwinding of the double helix under the co.nstraint exerted by the adsorption interactions and by the interfacial electric field. In a fundamental biophysicochemical sense the results enable general conclusions on the behaviour of DNA when it interacts with charged interfaces d.m the living cell

Исследование кинетики процесса полимеризации 5-норборнен-2,3дикарбоксимид-n-метил ацетата

Previous family studies revealed a large number of calpain 3 (CAPN3) mutations that cause recessive forms of limb girdle muscular dystrophy (LGMD2A) with selective atrophy of the proximal limb muscles. Correlations between the nature and site of a particular mutation and its corresponding phenotype, however, can only be established from homozygous mutations, which are particularly rare in the alternatively spliced NS, IS1 and IS2 regions of CAPN3. Here we identified a sibling pair with LGMD2A-type muscular dystrophy caused by a homozygous Ser606Leu (S606L) substitution in the IS2 linker domain. Normal protein levels, unaltered myofibrillar targeting and conserved calcium-induced autocatalytic activity of the mutated protein could be demonstrated in muscle biopsies from one patient. Despite this inconspicuous modification of the IS2 linker between domains III and IV, both patients developed signs and symptoms of the disease within their second decade of life. The unexpected severity of the clinical manifestation points to the high relevance of the calpain 3-specific IS2 segment between domains III and IV. We conclude that the structural motif around the Ser606 residue represents an important functional site that may regulate the transient activation and limited proteolysis of calpain 3