Latex bead immobilisation in PDMS matrix for the detection of p53 gene point mutation and anti-HIV-1 capsid protein antibodies

Two diagnostic chemiluminescent biochips were developed for either the detection of p53 gene point mutation or the serological detection of anti-HIV-1 p24 capsid protein. Both biochips were composed of 24 microarrays of latex beads spots (4×4) (150 m in diameter, 800 m spacing) entrapped in a poly(dimethylsiloxane) elastomer (PDMS). The latex beads, bearing oligonucleotide sequences or capsid protein, were spotted with a conventional piezoelectric spotter and subsequently transferred at the PDMS interface. The electron microscopy observation of the biochips showed how homogeneous and well distributed the spots could be. Point mutation detection on the codon 273 of the p53 gene was performed on the basis of the melting temperature difference between the perfect match sequence and the one base pair mismatch sequence. The hybridisation of a 20-mer oligonucleotide form the codon 273 including a one base pair mutation in its sequence on a biochip arrayed with non-muted and the muted complementary sequences, enabled a clear discrimination at 56°C between muted and wild sequences. Moreover, the quantitative measurement of the amount of muted sequence in a sample was possible in the range 0.4–4 pmol. Serological measurement of anti-HIV-1 p24 capsid protein on the biochip, prepared with 1-m-diameter latex beads, enabled the detection of monoclonal antibodies in the range 1.55–775 ng mL^–1. Such a range could be lowered to 0.775 ng mL^–1 when using 50-nm-diameter beads, which generated a higher specific surface. The validation of the biochip for the detection of anti-HIV-1 capsid protein antibodies was performed in human sera from seropositive and seronegative patients. The positivity of the sera was easily discriminated at serum dilutions below 1:1,000.     

Pion condensation and the σ-model in liquid neutron matter

The nature of the ground state of neutron matter at neutron star densities is discussed, starting from the linear σ-model Lagrangian. It is found that there is a possibility of a new, previously unknown, type of condensation, which involves coherent, non-vanishing expectation values of the neutral meson fields of the theory, the σ and π⁰ fields. The σπ⁰ condensate would, like normal neutron matter, develop its own π^? condensate. It is shown that the most general, translationally invariant, condensate is a combined σπ⁰ and π^? condensate with arbitrary, independent, wave numbers. The wave vectors of the condensates are determined by a minimization process, and are found to be non-vanishing and perpendicular.The σπ⁰ condensate corresponds to a state which is very different than previously considered states of neutron matter: all neutron spins are aligned, presumably with some macroscopic domain structure. Thus, criteria for the occurence of this condensate depend on the energy difference between very different states. This means that any prediction as to whether or not the state actually occurs in nature must at the moment be regarded as uncertain. However, using available hyperneted-chain calculations of the contribution to the energies from the direct neutron-neutron forces, it is demonstrated that a σπ⁰ condensate (with its accompanying π^? condensate) might well occur at neutron densities above perhaps 0.5 particles/fm³.This paper leans heavily on the linear σ-model. However, the neutral condensate is a general consequence of chiral symmetry, and can thus also be obtained e.g. from Weinberg's Lagrangian.     

Goodness-Of-Fit Tests Based on Estimated Expectations of Probability Integral Transformed Order Statistics

New goodness-of-fit tests, based on bootstrap estimated expectations of probability integral transformed order statistics, are derived for the location-scale model. The resulting test statistics are location and scale invariant, and are sensitive to discrepancies at the tails of the hypothesized distribution. The limiting null distributions of the test statistics are derived in terms of functionals of a certain Gaussian process, and the tests are shown to be consistent against a broad family of alternatives. Critical points for all sample sizes are provided for tests of normality. A simulation study shows that the proposed tests are more powerful than established tests such as Shapiro-Wilk, Cramér-von Mises and Anderson-Darling, for a wide range of alternative distributions.     

Effects of angular pump mismatch for the semi-linear oscillator

We investigate, analytically and numerically, the influence of an angular mismatch of counter-propagating pump beams on the threshold of oscillation for the photorefractive semi-linear oscillator driven by non-local non-linear response. Our analysis includes the frequency degenerate and non-degenerate regimes within a wide range of the variable input parameters—the coupling strength, the pump ratio, and the feedback mirror reflectivity. The limiting case of mirrorless oscillation is considered as well. The main outcome of our studies is the possibility of strong reduction of the oscillation threshold owing to the angular mismatch. Furthermore, increasing the mismatch induces pronounced bifurcations of the oscillation parameters, including transitions between degenerate and non-degenerate oscillation modes. The main findings are verified by direct simulations of the dynamic equations.     

Ultrafast nanoporous silica formation driven by femtosecond laser irradiation

A type of glass modifications occurring after femto‐second laser irradiation gives rise to strong (10⁻²) from birefringence. This form birefringence is thought to be related to index nanostructure (called nanogratings). Analyzing induced tracks in fused silica using scanning electron microscopy (SEM) with nm resolution shows that nanostructures are porous nanoplanes with an average index lower than typical silica (Δn ∼ –0.20). Their origin is explained as arising from fast decomposition of the glass under localized, high‐intensity femtosecond laser radiation where strong nonlinear, multiphoton‐induced photoionization leads to plasma generation. Mechanistic details include Coulombic explosions characteristic of strong photoionization and the production of self‐trapped exciton (STE). Rapid relaxation of these STE prevents recombination and dissociated atomic oxygen instead recombines with each other to form molecular oxygen pointed out using Raman microscopy. Some of it is dissolved in the condensed glass whilst the rest is trapped within nanovoids. A chemical recombination can only occur at 1200 °C for many hours. This explains the thermal stability of such a nanostructure. Precise laser translation and control of these birefringent nanoporous structures allo arbitrarily tuning and positioning within the glass, an important tool for controlling optical properties for photonic applications, catalysts, molecular sieves, composites and more.     

A stationary approach to inverse scattering for schrodinger operators with first order perturbation

In this paper, we study the inverse scattering of Schrodinger operators with short-range (resp. long-range) electric and magnetic potentials. We develop a stationary approach to determine the high energy asymptotics of the scattering operator (resp. modified scattering operator). As a corollary, we show that the electric potential and the magnetic field are uniquely determined by the first two terms of this asymptotic expansion.     

The Fundamentals of Real‐Time Surface Plasmon Resonance/Electrogenerated Chemiluminescence

We report the integration of surface plasmon resonance (SPR), cyclic voltammetry and electrochemiluminescence (ECL) responses to survey the interfacial adsorption and energy transfer processes involved in ECL on a plasmonic substrate. It was observed that a Tween 80/tripropylamine nonionic layer formed on the gold electrode of the SPR sensor, while enhancing the ECL emission process, affects the electron transfer process to the luminophore, Ru(bpy)₃²⁺, which in turn has an impact on the plasmon resonance. Concomitantly, the surface plasmon modulated the ECL intensity, which decreased by about 40 %, due to an interaction between the excited state of Ru(bpy)₃²⁺ and the plasmon. This occurred only when the plasmon was excited, demonstrating that the optically excited surface plasmon leads to lower plasmon‐mediated luminescence and that the plasmon interacts with the excited state of Ru(bpy)₃²⁺ within a very thin layer.