Inkjetting dielectric layer for electronic applications

Printed electronics is expected to increase its market share significantly in near future. The emerging applications include e.g. display applications, RFID tags, and photovoltaic applications. A benefit of printing is the additive character of the process, which means that material is deposited only the amount that is needed. Digital printing increases flexibility of the process, because circuits are manufactured directly from a digital file, which removes need of fixed masks or patterned screens for each layout. Formation of a multilayer circuitry requires printing of conductive and insulative layers. This paper focuses on printing of a dielectric layer with an inkjet printer. Six sigma DMAIC approach was applied during the process characterization and analysis. The study began by defining the process parameters and evaluating their importance to the outputs. Highest rated parameters were taken into consideration and a design of experiments was established. Measured values were analyzed and it was observed which parameters had the highest effect on the outputs. The results were further verified and it was observed that electrically the printed structures were successful.     

[FeFe]-hydrogenase gene quantification and melting curve analysis from hydrogen-fermenting bioreactor samples

In this study, quantitative PCR (qPCR) was used to quantify [FeFe]-hydrogenases and subsequently melting curves were analyzed from hydrogen-fermenting, mixed-culture bioreactor samples. Denaturing gradient gel electrophoresis (DGGE) analysis was also performed to the reactor samples revealing a clostridial dominance in the reactor. Primers targeting [FeFe]-hydrogenases were designed based on known clostridial [FeFe]-hydrogenase gene sequences and tested with several clostridial strains. The results show that amplification efficiencies of four different clostridia are highly similar and melting curves of the clostridial strains were within 1 °C of each other. We compared the melting curves to the hydrogen percentage and observed a correlation between the results. The closer the melting curves were to those of clostridia, the better the hydrogen production. Based on these results, the primers and melting curve analysis of [FeFe]-hydrogenase amplicons can be used for analysing hydrogenase genes from bioreactor samples.     

The pairing of a wavelet basis with a mildly redundant analysis via subband regression

A distinction is usually made between wavelet bases and wavelet frames. The former are associated with a one-to-one representation of signals, which is somewhat constrained but most efficient computationally. The latter are over-complete, but they offer advantages in terms of flexibility (shape of the basis functions) and shift-invariance. In this paper, we propose a framework for improved wavelet analysis based on an appropriate pairing of a wavelet basis with a mildly redundant version of itself (frame). The processing is accomplished in four steps: 1) redundant wavelet analysis, 2) wavelet-domain processing, 3) projection of the results onto the wavelet basis, and 4) reconstruction of the signal from its nonredundant wavelet expansion. The wavelet analysis is pyramid-like and is obtained by simple modification of Mallat's filterbank algorithm (e.g., suppression of the down-sampling in the wavelet channels only). The key component of the method is the subband regression filter (Step 3) which computes a wavelet expansion that is maximally consistent in the least squares sense with the redundant wavelet analysis. We demonstrate that this approach significantly improves the performance of soft-threshold wavelet denoising with a moderate increase in computational cost. We also show that the analysis filters in the proposed framework can be adjusted for improved feature detection; in particular, a new quincunx Mexican-hat-like wavelet transform that is fully reversible and essentially behaves the (gamma/2)th Laplacian of a Gaussian.     

BSLIM: Spectral Localization by Imaging With Explicit B0 Field Inhomogeneity Compensation

Magnetic resonance spectroscopy imaging (MRSI) is an attractive tool for medical imaging. However, its practical use is often limited by the intrinsic low spatial resolution and long acquisition time. Spectral localization by imaging (SLIM) has been proposed as a non-Fourier reconstruction algorithm that incorporates spatial a priori information about spectroscopically uniform compartments. Unfortunately, the influence of the magnetic field inhomogeneity - in particular, the susceptibility effects at tissues' boundaries - undermines the validity of the compartmental model. Therefore, we propose BSLIM as an extension of SLIM with field inhomogeneity compensation. A B₀-field inhomogeneity map, which can be acquired rapidly and at high resolution, is used by the new algorithm as additional a priori information. We show that the proposed method is distinct from the generalized SLIM (GSLIM) framework. Experimental results of a two-compartment phantom demonstrate the feasibility of the method and the importance of inhomogeneity compensation.     

A dynamic model for plug flow reactor state profiles

A dynamic model for state profiles of a plug flow reactor is developed, including multiple fluid and solid phases. The model is based on conservation of reactor state profile moments along the spatial dimension of the reactor. These moments are transformed analytically into a polynomial approximation at each time step. The method is flexible, and low as well as high order numerical schemes are resulted in by appropriate choice of parameters. A significant advantage of the present method is that boundary conditions of the partial differential equation reactor model are implicitly satisfied via the moment transformation, whereas the polynomial profile in the numerical solution does not have to be forced to satisfy the boundary conditions. The method is tested numerically against analytical solutions in three numerically challenging benchmark cases: prediction of breakthrough curve in packed bed adsorbers; simulation of chromatographic separation; and feeding a step impulse in a plug flow dimerization reactor. It is shown that the high resolution methods result in considerably smaller numerical errors than a simple low-order assumption of piecewise continuous solution.     

γ-(S)-Guanidinylmethyl-Modified Triplex-Forming Peptide Nucleic Acids Increase Hoogsteen-Face Affinity for a MicroRNA and Enhance Cellular Uptake

γ-Modified (i.e., (S)-aminomethyl, (S)-acetamidomethyl, (R)-4-(hydroxymethyl)triazol-1-ylmethyl, and (S)-guanidinylmethyl) triplex-forming peptide nucleic acids (TFPNAs) were synthesized and the effect of the backbone modifications on the binding to a miR-215 model was studied. Among the modifications, an appropriate pattern of three γ-(S)-guanidinylmethyl modifications increased the affinity and Hoogsteen-face selectivity for the miR-215 model without ternary (PNA)₂/RNA complex formation. Moreover, the γ-(S)-guanidinylmethyl groups were observed to facilitate internalization of the TFPNAs into living PC-3 prostate cancer cells.     

Hypoxia and flow perfusion modulate proliferation and gene expression of articular chondrocytes on porous scaffolds

The combination of reduced oxygen tension and flow perfusion bioreactor culture is investigated for its effect on the proliferation, glycosaminoglycan production, and chondrogenic gene expression of bovine articular chondrocytes on porous polymer scaffolds. It was hypothesized that the combination of such factors would more closely replicate the in situ environment of these cells, leading to improvements in the cell phenotype. Chondrocytes were seeded onto electrospun poly(ε‐caprolactone) scaffolds and cultured in static or perfusion culture in either normoxic or hypoxic conditions for 6days. Results demonstrated that the combination of hypoxic and perfusion culture led to an increase in chondrocyte proliferation and glycosaminoglycan production, as well as an improvement in the ratio of collagen II/I gene expression over perfusion culture alone. The results demonstrate the need to combine multiple signals in vitro, in order to improve tissue growth by more closely replicating the native environment of cells. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3158–3166, 2013     

Energy crop cultivations of reed canary grass — An inferior breeding habitat for the skylark,a characteristic farmland bird species

Here, I present the first comparison of the abundance of farmland birds in energy grass fields and in cereal-dominated conventionally cultivated fields (CCFs). I demonstrate that in boreal farmland, skylark (Alauda arvensis) densities were significantly lower in reed canary grass (RCG) (Phalaris arundinacea) fields than in CCFs. I found that during the early breeding season RCG fields and CCFs are equally good habitats, but over the ensuing couple of weeks RCG rapidly grows too tall and dense for field-nesting species. Consequently, RCG is an inferior habitat for skylark for laying replacement clutches (after failure of first nesting) or for a second clutch after one successful nesting. The results imply that if RCG cultivation is to be expanded, the establishment of large monocultures should be avoided in farmland landscapes; otherwise the novel habitat may affect detrimentally the seriously depleted skylark population, and probably also other field-nesting bird species with similar breeding habitats.     

Prediction of Power Losses Due to Tooth Friction in Gears

Sliding friction between gear teeth is recognized as one of the main sources of power loss in geared transmissions as well as a potential source of vibration and noise. Its accurate modeling is therefore of primary importance in efficiency and vibration analyses of mechanical transmissions. For lubricated contacts, various empirical friction laws based on results from simulators can be found in the literature. One of their limitations comes from the specimen surface texture, which is often different to that of actual gears. Moreover, most of these models were established for high slide-to-roll ratios and cannot be used for low slide-to-roll ratios as encountered near the pitch point in gears. In this article, friction measurements were derived from an EHL simulator with contact conditions and surface finish close to those in gears and which covers a wide range of sliding/rolling conditions. A new traction law is proposed and integrated in a three-dimensional dynamic model of gears with consideration of tooth friction. The numerical results are then compared with the experimental evidence from a gear test rig. It is observed that tooth friction can strongly affect dynamic transmissibility through bearing mounts. Finally, the need of an accurate friction model for reliable power loss predictions is stressed.