Analysis of Amyloid-β Peptides in Cerebrospinal Fluid Samples by Capillary Electrophoresis Coupled with LIF Detection

We report a CE-LIF method for the separation and detection of five synthetic amyloid-β peptides corresponding to an important family of CSF-biomarkers in the context of Alzheimer disease (AD). The presumed most relevant peptides (Aβ1-42, Aβ1-40, and Aβ1-38) that may support the differentiation between AD and healthy patients or other dementias were successfully detected in CSF by incorporating an immunoconcentration step prior to CE analysis of derivatized peptides. We labeled the Aβ peptides with a fluoroprobe dye before CE-LIF analysis. This reagent reacts with the amino groups of lysine residues and produced mostly ditagged Aβ peptides under the proposed experimental conditions. The labeling reaction displayed similar efficiency with each one of the five different synthetic Aβ peptides that were tested. The limit of detection of the CE-LIF method approached 280 attomoles of injected synthetic labeled Aβ peptides. We obtained excellent correlation between peak areas and peptide concentrations from 35 nM to 750 nM. For the detection of Aβ peptides in human CSF samples, we enriched the peptides by immunoprecipitation prior to the CE-LIF analysis. The comparison of the CE-LIF profiles obtained from CSF samples from 3 AD patients and 4 non-demented control subjects indicated noticeable differences, suggesting that this method, which relies on a multibiomarker approach, may have potential as a clinical diagnostic test for AD.     

NMR-based structural glycomics for high-throughput screening of carbohydrate-active enzyme specificity

We report here the development of a straightforward, sensitive, and quantitative NMR-based method for high-throughput characterization of carbohydrate structure and screening of carbohydrate active enzyme (CAZyme) specificity. Automated assays starting from gene library expression to carbohydrate structure determination directly from crude reaction media have been established and successfully used to screen a library of 4032 CAZymes obtained by combinatorial engineering, at a rate of 480 enzyme variants per day. This allowed one to accurately discriminate 303 enzyme variants with altered specificity. The results demonstrate the potential of high-throughput NMR technology in glycomics, to mine artificial and natural enzyme diversity for novel biocatalysts.     

Förster resonance energy transfer imaging in vivo with approximated radiative transfer equation

We describe a new light transport model, which was applied to three-dimensional lifetime imaging of F?rster resonance energy transfer in mice in vivo. The model is an approximation to the radiative transfer equation and combines light diffusion and ray optics. This approximation is well adopted to wide-field time-gated intensity-based data acquisition. Reconstructed image data are presented and compared with results obtained by using the telegraph equation approximation. The new approach provides improved recovery of absorption and scattering parameters while returning similar values for the fluorescence parameters.     

Nonlinear plasmonics at planar metal surfaces

We investigate the nonlinear optical response of a noble metal surface. We derive the components of the third-order nonlinear susceptibility and determine an absolute value of χ((3))≈0.2 nm(2) V(-2), a value that is more than two orders of magnitude larger than the values found for typical nonlinear laser crystals. Using nonlinear four-wave mixing (4WM) with incident laser pulses of frequencies ω(1) and ω(2), we generate fields oscillating at the nonlinear frequency ω(4WM)=2ω(1)-ω(2). We identify and discuss three distinct regimes: (i) a regime where the 4WM field is propagating, (ii) a regime where it is evanescent, and (iii) a regime where the nonlinear response couples to surface plasmon polaritons.     

Statistical analysis of effects of industrial processing steps on functional properties of pasteurised liquid egg white

Egg white is widely used as an ingredient in the food industry owing to its excellent functional properties. The transformation of shell eggs into safe liquid, frozen, or spray‐dried egg white with extended shelf life requires many technological operations that result in modifications to the egg white's functional properties. The present study highlights the critical steps affecting foaming and gelling properties during a classical pasteurised liquid egg white process. The main source of variation in functional properties was raw material quality, accounting for 70% of the variability. Part of the remaining 30% was explained by mechanical egg white–yolk separation, tank storage, pasteurisation and homogenisation that resulted in damage to the functional properties, whereas initial flow through pipes and pumping resulted in their improvement. The effects of these steps could be grouped according to the type of treatment undertaken. Dry matter content, pH and treatment intensity at each step contributed about 30% of the variability in functional properties due to processing steps. Relationships between the modifications of egg white functional properties and protein conformation were established. Between 46 and 78% of the variability in functional properties can be explained by protein denaturation, temperature and enthalpy changes. Copyright © 2004 Society of Chemical Industry     

Generalized-α scheme in the PFEM for velocity-pressure and displacement-pressure formulations of the incompressible Navier–Stokes equations

Despite the increasing use of the particle finite element method (PFEM) in fluid flow simulation and the outstanding success of the Generalized-$\alpha$ (GA) time integration method, very little discussion has been devoted to their combined performance. This work aims to contribute in this regard by addressing three main aspects. First, it includes a detailed implementation analysis of the GA method in PFEM. The work recognizes and compares different implementation approaches from the literature, which differ mainly in the terms that are $\alpha$-interpolated (state variables or forces of momentum equation) and the type of treatment for the pressure in the time integration scheme. Second, the work compares the performance of the GA method against the Backward Euler and Newmark schemes for the solution of the incompressible Navier–Stokes equations. Third, the study is enriched by considering not only the classical velocity-pressure formulation but also the displacement-pressure formulation that is gaining interest in the fluid-structure interaction field. The work is carried out using various 2D and 3D benchmark problems such as the fluid sloshing, the solitary wave propagation, the flow around a cylinder, and the collapse of a cylindrical water column.     

Online handwriting trajectory reconstruction from kinematic sensors using temporal convolutional network

International Journal on Document Analysis and Recognition (IJDAR) - Handwriting with digital pens is a common way to facilitate human–computer interaction through the use of online...     

Nanoscale Surface Analysis Reveals Origins of Enhanced Interface Passivation in RbF Post Deposition Treated CIGSe Solar Cells

Alkali post deposition treatments (PDTs) of Cu(In,Ga)Se₂ absorbers have boosted the power conversion efficiency (PCE) of the solar cell devices in the last years. A detailed model explaining how the PDTs impact the optoelectronic properties at the nanoscale is still lacking. Here, via various scanning probe techniques, X-Ray photo-electron spectroscopy and high resolution secondary ion mass spectroscopy it is shown that the RbF PDT treatments lead to a one to one exchange of Rb with Cu at the surface. This exchange takes place in the naturally occurring Cu-depleted CIGSe surface, known as the ordered vacancy compound. A detailed comparison between samples with different PDTs after various cleaning procedures furthermore highlights the necessity to perform all the measurements on NH₄OH cleaning surfaces only. After NH₄OH, no RbInSe₂ phase could be detected at the surface anymore and the surface bandgap, as measured with scanning tunneling spectroscopy is only 1.7 eV. The findings demonstrate that the existence of a RbInSe₂ phase is most likely not responsible for the recent improvements in power conversion efficiency for state of the art solar cells. The primary effect of the PDT treatment is a modification of the ordered vacancy compound, where Cu is exchanged with Rb.