Electrochemical and microgravimetric studies of poly[3,4-ethylenedioxythiophene]-tyrosinase biocomposite material electrodeposited onto gold electrodes by a sinusoidal voltages method

The electrodeposition of poly(3,4-ethylenedioxythiophene)-tyrosinase (PEDOT-Ty) biocomposite material onto gold electrode has been achieved by means of a sinusoidal voltages (SV) method. The SV method consists in the superimposition of a sinusoidal voltage (sin wave) with fixed frequency and amplitude onto a d.c. potential. The influence of electrochemical parameters like frequency and amplitude of SV signal, d.c. potential value, deposition time, on the electrodeposition process has been investigated. The biocomposite material has been prepared as a thin layer onto quartz crystals coated with gold. The frequency change of the quartz crystal during the electrodeposition of the biocomposite material was recorded simultaneously with the measured current response. The morphology of the deposited PEDOT-Ty coatings was investigated by scanning electron microscopy. The electrochemical behavior of the biocomposite material in aqueous solution was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The use of d.c. potential value of 0.6 V revealed the contribution of the SV component to the electrodeposition process. The PEDOT-Ty modified electrode was used as an electrochemical biosensor in the voltammetric determination of dopamine in the presence of hydroquinone. The analytical performances of the prepared biosensors were also investigated.     

On-line bioaffinity-electrospray mass spectrometry for simultaneous detection,identification, and quantification of protein-ligand interactions

We describe here an on-line combination of a surface acoustic wave (SAW) biosensor with electrospray ionization mass spectrometry (SAW-ESI-MS) that enables the direct detection, identification, and quantification of affinity-bound ligands from a protein-ligand complex on a biosensor chip. A trapping column was used between the SAW-biosensor and the electrospray mass spectrometer equipped with a micro-guard column, which provides simultaneous sample concentration and desalting for the mass spectrometric analysis of the dissociated ligand. First applications of the on-line SAW-ESI-MS combination include (1), differentiation of β-amyloid (Aβ) epitope peptides bound to anti-Aβ antibodies; (2), the identification of immobilized Substance P peptide-calmodulin complex; (3), identification and quantification of the interaction of 3-nitrotyrosine-modified peptides with nitrotyrosine-specific antibodies; and (4), identification of immobilized anti-α-synuclein-human α-synuclein complex. Quantitative determinations of protein-ligand complexes by SAW yielded dissociation constants (K_D) from micro-to low nanomolar sample concentrations. The on-line bioaffinity-ESI-MS combination presented here is expected to enable broad bioanalytical application to the simultaneous, label-free determination and quantification of biopolymer-ligand interactions, as diverse as antigen-antibody and lectin-carbohydrate complexes.     

Weak solutions for antiplane models involving elastic materials with degeneracies

We study the antiplane shear deformation of a cylindrical body in frictional contact with a rigid foundation, under the hypothesis of the small deformations. The envisaged material is assumed to be elastic, physically nonlinear and nonhomogeneous, such that the Lamé coefficient μ satisfies ${{\rm inf}_{{\bf x}\in\Omega}\,\mu(\bf x)=0}$ , where Ω denotes the cross section of the cylinder. We establish the existence of a unique weak solution for this model on an appropriate weighted functional space. The proof is based on arguments of variational inequalities with strongly monotone operators.     

Weak solutions for nonlinear antiplane problems leading to hemivariational inequalities

We analyze the antiplane shear deformation of an elastic cylinder in frictional contact with a rigid foundation, for static processes, under the small deformation hypothesis. Based on the Knaster–Kuratowski–Mazurkiewicz technique in the theory of the hemivariational inequalities, we prove that the model has at least one weak solution. Moreover, we present several examples of constitutive laws and friction laws for which our theoretical results are valid. Finally, we comment on the conditions which guarantee the uniqueness of the solution.     

A regularity result for a minimum problem in orlicz-sobolev spaces with applications in the study of the dirichlet problem for the operator of hencky-nadai theory

The existence and uniqueness of the solution to the problem of minimum for functionals generated by N- functions are obtained in Orlicz-Sobolev spaces. Applications for some functionals dealing with Hencky theory are given.     

Second-Order Corrections to Mean Field Evolution of Weakly Interacting Bosons. I.

Inspired by the works of Rodnianski and Schlein [31] and Wu [34,35], we derive a new nonlinear Schrödinger equation that describes a second-order correction to the usual tensor product (mean-field) approximation for the Hamiltonian evolution of a many-particle system in Bose-Einstein condensation. We show that our new equation, if it has solutions with appropriate smoothness and decay properties, implies a new Fock space estimate. We also show that for an interaction potential ${v(x)= \epsilon \chi(x) |x|^{-1}}Inspired by the works of Rodnianski and Schlein [31] and Wu [34,35], we derive a new nonlinear Schr?dinger equation that describes a second-order correction to the usual tensor product (mean-field) approximation for the Hamiltonian evolution of a many-particle system in Bose-Einstein condensation. We show that our new equation, if it has solutions with appropriate smoothness and decay properties, implies a new Fock space estimate. We also show that for an interaction potential v(x) = ec(x) |x|^-1{v(x)= \epsilon \chi(x) |x|^{-1}}, where e{\epsilon} is sufficiently small and c ? C₀^￥{\chi \in C_0^{\infty}} even, our program can be easily implemented locally in time. We leave global in time issues, more singular potentials and sophisticated estimates for a subsequent part (Part II) of this paper.     

Reducing the bandwidth of a sparse matrix with a genetic algorithm

Abstract

The matrix bandwidth minimization problem (MBMP) consists in finding a permutation of the lines and columns of a given sparse matrix in order to keep the non-zero elements in a band that is as close as possible to the main diagonal. Equivalently in terms of graph theory, MBMP is defined as the problem of finding a labelling of the vertices of a given graph G such that its bandwidth is minimized. In this paper, we propose an improved genetic algorithm (GA)-based heuristic for solving the matrix bandwidth minimization problem, motivated by its robustness and efficiency in a wide area of optimization problems. Extensively computational results are reported for an often used set of benchmark instances. The obtained results on the different instances investigated show improvement of the quality of the solutions and demonstrate the efficiency of our GA compared to the existing methods in the literature.     

Many-body interactions in semiconductors probed by optical two-dimensional fourier transform spectroscopy

We study many-body interactions between excitons in semiconductors by applying the powerful technique of optical two-dimensional Fourier transform spectroscopy. A two-dimensional spectrum correlates the phase (frequency) evolution of the nonlinear polarization field during the initial evolution and the final detection period. A single two-dimensional spectrum can identify couplings between resonances, separate quantum mechanical pathways, and distinguish among microscopic many-body interactions.     

Qualitative and quantitative determination of human biomarkers by laser photoacoustic spectroscopy methods

The hypothesis that blood, urine and other body fluids and tissues can be sampled and analyzed to produce clinical information for disease diagnosis or therapy monitoring is the basis of modern clinical diagnosis and medical practice. The analysis of breath air has major advantages because it is a non-invasive method, represents minimal risk to personnel collecting the samples and can be often sampled. Breath air samples from the human subjects were collected using aluminized bags from QuinTron and analyzed using the laser photoacoustic spectroscopy (LPAS) technique. LPAS is used to detect traces of ethylene in breath air resulting from lipid peroxidation in lung epithelium following the radiotherapy and also traces of ammonia from patients subjected to hemodialysis for treatment of renal failure. In the case of patients affected by cancer and treated by external radiotherapy, all measurements were done at 10P(14) CO₂ laser line, where the ethylene absorption coefficient has the largest value (30.4 cm⁻¹ atm⁻¹), whereas for patients affected by renal failure and treated by standard dialysis, all measurements were performed at 9R(30) CO₂ laser line, where the ammonia absorption coefficient has the maximum value of 57 cm⁻¹ atm⁻¹. The levels of ethylene and ammonia in exhaled air, from patients with cancer and renal failure, respectively, were measured and compared with breath air contents from healthy humans. Human gas biomarkers were measured at sub-ppb (parts per billion) concentration sensitivities. It has been demonstrated that LPAS technique will play an important role in the future of exhaled breath air analysis. The key attributes of this technique are sensitivity, selectivity, fast and real time response, as well as its simplicity.