Bulk heterojunction solar cells using thieno[3,4-c]pyrrole-4,6-dione and dithieno[3,2-b:2',3'-d]silole copolymer with a power conversion efficiency of 7.3%

A new alternating copolymer of dithienosilole and thienopyrrole-4,6-dione (PDTSTPD) possesses both a low optical bandgap (1.73 eV) and a deep highest occupied molecular orbital energy level (5.57 eV). The introduction of branched alkyl chains to the dithienosilole unit was found to be critical for the improvement of the polymer solubility. When blended with PC(71)BM, PDTSTPD exhibited a power conversion efficiency of 7.3% on the photovoltaic devices with an active area of 1 cm(2).     

Enzymatic biosensors based on SWCNT-conducting polymer electrodes

This short review is focused on recent advances in the combination of conducting polymers and SWCNTs for the fabrication of electrochemical biosensors. The different properties of conducting polymers and SWCNTs are discussed in respect of their use in immobilizing and wiring biomolecules on electrode surfaces. We further describe the functionalization techniques used in the fabrication of these devices and their associated biosensing performances.     

Simultaneous determination of three 5-nitroimidazoles in foodstuffs by differential pulse voltammetry and chemometrics

The voltammetric behaviour of three 5-nitroimidazoles,metronidazole,tinidazole and ornidazole,was investigated,and a method was developed for the simultaneous determination of these compounds,based on their reduction at a hanging mercury drop electrode(HMDE) in pH 8.95 buffer with differential pulse voltammetric(DPV) approach.Well defined voltammetric waves with peak potentials of -692,-640 and -652 mV were observed for these compounds,respectively.It is difficult to determine them individually from their mixtures without preseparation,for their voltammetric peaks overlapped seriously,so the chemometrics were used to resolve the overlapped voltammogram and quantify the mixtures.The proposed method was successfully applied to the determination of three 5-nitroimidazoles in milk and honey samples.     

Divergent synthetic approach to 6'-modified α-GalCer analogues

A synthetic approach is presented for the synthesis of galacturonic acid and D-fucosyl modified KRN7000. The approach allows for late-stage functionalisation of both the sugar 6'-OH and the sphingosine amino groups, which enables convenient synthesis of promising 6'-modified KRN7000 analogues.     

Stopping rules and backward error analysis for bound-constrained optimization

Termination criteria for the iterative solution of bound-constrained optimization problems are examined in the light of backward error analysis. It is shown that the problem of determining a suitable perturbation on the problem’s data corresponding to the definition of the backward error is analytically solvable under mild assumptions. Moreover, a link between existing termination criteria and this solution is clarified, indicating that some standard measures of criticality may be interpreted in the sense of backward error analysis. The backward error problem is finally considered from the multicriteria optimization point of view and some numerical illustration is provided.     

Approximation of stationary solutions of Gaussian driven stochastic differential equations

We study sequences of empirical measures of Euler schemes associated to some non-Markovian SDEs: SDEs driven by Gaussian processes with stationary increments. We obtain the functional convergence of this sequence to a stationary solution to the SDE. Then, we end the paper by some specific properties of this stationary solution. We show that, in contrast to Markovian SDEs, its initial random value and the driving Gaussian process are always dependent. However, under an integral representation assumption, we also obtain that the past of the solution is independent of the future of the underlying innovation process of the Gaussian driving process.     

Forms of Lepage type and the balance systems

In this work we apply infinitesimal variational calculus to the systems of balance equations. We determine a class of the exterior $n+(n+1)$-forms Θ on the jet bundle of infinite order over a configurational bundle $\pi :Y^{n+m}\to X^n$ similar to the class of Lepage n-forms. Systems of differential equations obtained in the way similar to one used in the Lagrangian field theory, include the Euler–Lagrange equations corresponding to a Lagrangian functions as well as arbitrary regular systems of balance equations. For a balance system with a symmetry group G we present the Noether balance laws corresponding to the generators of the Lie algebra of the group G.     

Optimal control of the Stokes equations: conforming and non-conforming finite element methods under reduced regularity

This paper deals with a control-constrained linear-quadratic optimal control problem governed by the Stokes equations. It is concerned with situations where the gradient of the velocity field is not bounded. The control is discretized by piecewise constant functions. The state and the adjoint state are discretized by finite element schemes that are not necessarily conforming. The approximate control is constructed as projection of the discrete adjoint velocity in the set of admissible controls. It is proved that under certain assumptions on the discretization of state and adjoint state this approximation is of order 2 in L ²(Ω). As first example a prismatic domain with a reentrant edge is considered where the impact of the edge singularity is counteracted by anisotropic mesh grading and where the state and the adjoint state are approximated in the lower order Crouzeix-Raviart finite element space. The second example concerns a nonconvex, plane domain, where the corner singularity is treated by isotropic mesh grading and state and adjoint state can be approximated by a couple of standard element pairs.     

Quantitative impact of small angle forward scatter on whole blood oximetry using a Beer-Lambert absorbance model

It is well known that red blood cell scattering has an impact on whole blood oximetry as well as in vivo retinal oxygen saturation measurements. The goal of this study was to quantify the impact of small angle forward scatter on whole blood oximetry for scattering angles found in retinal oximetry light paths. Transmittance spectra of whole blood were measured in two different experimental setups: one that included small angle scatter in the transmitted signal and one that measured the transmitted signal only, at absorbance path lengths of 25, 50, 100, 250 and 500 μm. Oxygen saturation was determined by multiple linear regression in the 520-600 nm wavelength range and compared between path lengths and experimental setups. Mean calculated oxygen saturation differences between setups were greater than 10% at every absorbance path length. The deviations to the Beer-Lambert absorbance model had different spectral dependences between experimental setups, with the highest deviations found in the 520-540 nm range when scatter was added to the transmitted signal. These results are consistent with other models of forward scatter that predict different spectral dependences of the red blood cell scattering cross-section and haemoglobin extinction coefficients in this wavelength range.     

First identification of dimethoxycinnamic acids in human plasma after coffee intake by liquid chromatography-mass spectrometry

There is a substantial amount of published literature on the bioavailability of various coffee components including the most abundant metabolites, caffeic and ferulic acids. Surprisingly, to date, the appearance of dimethoxycinnamic acid derivatives in humans has not been reported despite the fact that methylated form of catechol-type polyphenols could help maintain, modify or even improve their biological activities. This study reports an LC-MS method for the detection of dimethoxycinnamic acid in human plasma after treatment with an esterase. Liquid chromatography, including the combination of methanol and acetonitrile as organic eluent, was optimized to resolve all interferences and enable reliable detection and identification of 3,4-dimethoxycinnamic and 3,4-dimethoxy-dihydrocinnamic acids. In addition to the good mass accuracy achieved (better than 5 ppm), tandem mass spectrometric and co-chromatography experiments further confirmed the identity of the compounds. The optimized method was applied to analyze samples obtained immediately, 1 and 10 h after coffee ingestion. The results show that in particular 3,4-dimethoxycinnamic acid appears in high abundance (～380 nM at 60 min) in plasma upon coffee intake, indicating that it is important to consider these derivatives in future bioavailability and bioefficacy studies.