An innovative strategy for direct electrochemical detection of microRNA biomarkers

We report an electrochemical method for direct, reagentless, and label-free detection of microRNA, based on a conjugated copolymer, poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-2-carboxyethyl-1,4-naphthoquinone), acting as hybridization transducer. Hybridization between the oligonucleotide capture probe and a microRNA target of 22 base pairs generates an increase in the redox current (“signal-on”), which is evidenced by square wave voltammetry. Selectivity is good, with little hybridization for non-complementary targets, and the limit of detection reaches 650 fM. It is also evidenced that this sensitivity benefits from the high affinity of DNA for RNA.

Nonlinear vibration response of shear deformable FGM sandwich toroidal shell segments

Meccanica - The nonlinear vibration investigation of toroidal shell segment (TSS) with an analytical approach is presented in this paper. The TSS is considered as a sandwich structure with FGM core...     

An Upper Bound Kinematic Approach to the Shakedown Analysis of Structures

A reduced but equivalent form of Koiter's upper bound kinematic theorem, which does not involve time integrals, is deduced, provided that the plastic strain rates at every point of a structure are confined to a certain number of possible directions in the strain space. Generally it yields an upper bound on the shakedown factor, which improves upon the previous one by Pham and Stumpf.Sommario. Una forma ridotta ma equivalente del teorema cinematica di Koiter sul limite superiore, che non coinvolge integrali temporali, viene dedotta sotto la condizione che le velocità di deformazione plastica in ogni punto della struttura siano confinate ad un certo numero di possibili direzioni nello spazio delle deformazioni. Generalmente, ciò produce un limite superiore sul fattore di shakedown, che migliora quello precedente di Pham e Stumpf.     

Hydrogen evolution during deposition of microcrystalline silicon by chemical transport

We exposed a freshly deposited boron-doped, hydrogenated amorphous silicon (a-Si:H) layer to hydrogen plasma under conditions of chemical transport. In situ spectroscopic ellipsometry measurements revealed that atomic hydrogen impinging on the film surface behaves differently before and after crystallization. First, the plasma exposure increases hydrogen solubility in the a-Si:H network leading to the formation of a hydrogen-rich subsurface layer. Then, once the crystallization process engages, the excess hydrogen starts to leave the sample. We have attributed this unusual evolution of the excess hydrogen to the grown hydrogenated microcrystalline (μc-Si:H) layer, which gradually prevents the atomic hydrogen from the plasma reaching the μc-Si:H/a-Si:H interface. Consequently, hydrogen solubility, initially increased by the hydrogen plasma, recovers the initial value of an untreated a-Si:H material. To support the theory that the outdiffusion is a consequence and not the cause of the μc-Si:H layer growth, we solved the combined diffusion and trapping equations, which govern hydrogen diffusion into the sample, using appropriate approximations and a specific boundary condition explaining the lack of hydrogen injection during μc-Si:H layer growth.     

Electroweak precision constraints on the electroweak-scale right-handed neutrino model

A model of electroweak-scale right-handed neutrino (EW_νR$\text{EW}{\nu }_R$) model was constructed five years ago in which the right-handed neutrinos are members of mirror fermion weak doublets and where the Majorana masses of the right-handed neutrinos are found to be naturally of the order of the electroweak scale. These features facilitate their searches at the LHC through signals such as like-sign dilepton events. This model contains, in addition to the mirror quarks and leptons, extra scalars transforming as weak triplets. In this paper, we study the constraints imposed on these additional particles by the electroweak precision parameters S, T, and U  . These constraints are crucial in determining the viability of the electroweak _νR${\nu }_R$ model and the allowed parameter space needed for a detailed phenomenology of the model.     

Unstable Process Identification in a Pure Thermal Plume under Forced Rotating Conditions

A pure thermal plume development arising from a finite-size rotating heat source was analyzed experimentally. Qualitative investigation through extensive visualization has brought into focus the existence of a threshold rotation frequency (i.e., a swirl number) above which stretching effects are strengthened, thereby forcing the ascending plume motion to spiral around the geometrical axis heat source. Nevertheless, above the threshold frequency (i.e., above the swirl number), unstable processes appear through flow field pulsation in close proximity to the heat source; the pulsations literally beat and drive the flow field vicinity. From a strictly quantitative point of view, the data underscore the fact that heat source rotation presents two opposed trends. Below the threshold frequency, the higher the frequency, the more the temperature level is concentrated on the plume axis. In contrast, at the strongest rotation frequencies studied, the opposite is observed. Above the threshold rotating frequency, the characteristic rotating time scale appears to be too short to interact with the characteristic plume time scale. As a consequence, rotation of the heat source enhances transition from laminar to turbulence.     

Stability of Solutions of a Quasilinear Index-2 Tractable Differential Algebraic Equation by the Lyapunov Second Method

The Lyapunov second method is an important tool in the qualitative theory of ordinary differential equations. In this paper, we consider the behavior of solutions of quasilinear index-2 tractable differential algebraic equations. Using the Lyapunov second method, we prove sufficient conditions for the stability of zero solution of such equations.__________Published in Ukrains’kyi Matematychnyi Zhurnal, Vol. 56, No. 10, pp. 1321 – 1334, October, 2004.     

Cost Cumulant Control: State-Feedback,Finite-Horizon Paradigm with Application to Seismic Protection

The paper is concerned with the study of the optimal control which minimizes a finite linear combination of the first k cost cumulants of a finite-horizon integral quadratic form associated with a linear stochastic system, when the controller measures the states. The solution is investigated by adapting dynamic programming techniques to the nontraditional forms evidenced by cumulant representations. The performance of this k-cost cumulant (kCC) controller is compared to that of the best control paradigms published for the American Society of Civil Engineers first-generation structure benchmark for seismically excited buildings; the simulation results indicate that the newly developed control paradigm makes better use of the available control limits and achieves uniform improvement in the officially defined performance statistics for floor vibrations and accelerations.     

Rational Brauer characters

It is known that every finite group of even order has a non-trivial complex irreducible character which is rational valued. We prove the modular version of this result: If p is an odd prime and G is any finite group of even order, then G has a non-trivial irreducible p-Brauer character which is rational valued. The first author is partially supported by the Ministerio de Educación y Ciencia proyecto MTM2004-06067-C02-01, while the second gratefully acknowledges the support of the NSA (grant H98230-04-0066).