Near-Infrared Imaging Spectroscopy as a Tool to Discriminate Two Cryptic Tetramorium Ant Species

Correct species identification is a precondition for many ecological studies. Morphologically highly similar, i.e., cryptic, species are an important component of biodiversity but particularly difficult to discriminate and therefore understudied ecologically. To find new methods for their rapid identification, thus, is important. The cuticle's chemical signature of insects often is unique for species. Near-infrared spectroscopy (NIRS) can capture such signatures. Imaging NIRS facilitates precise positioning of the measurement area on biological objects and high-resolution spatial capturing. Here, we tested the applicability of imaging NIRS to the discrimination of cryptic species by using the ants Tetramorium caespitum and T. impurum. The classification success of Partial Least Squares Regression was 98.8%. Principal Component Analysis grouped spectra of some T. impurum individuals with T. caespitum. Combined with molecular-genetic and morphological evidence, this result enabled us to pose testable hypotheses about the biology of these species. We conclude that discrimination of T. caespitum and T. impurum with imaging NIRS is possible, promising that imaging NIRS could become a time- and cost-efficient tool for the reliable discrimination of cryptic species. This and the direct facilitation of potential biological insight beyond species identification underscore the value of imaging NIRS to ecology.     

The Ketosynthase Domain Controls Chain Length in Mushroom Oligocyclic Polyketide Synthases

The nonreducing iterative type I polyketide synthases (NR-PKSs) CoPKS1 and CoPKS4 of the webcap mushroom Cortinarius odorifer share 88 % identical amino acids. CoPKS1 almost exclusively produces a tricyclic octaketide product, atrochrysone carboxylic acid, whereas CoPKS4 shows simultaneous hepta- and octaketide synthase activity and also produces the bicyclic heptaketide 6-hydroxymusizin. To identify the region(s) controlling chain length, four chimeric enzyme variants were constructed and assayed for activity in Aspergillus niger as heterologous expression platform. We provide evidence that the β-ketoacyl synthase (KS) domain determines chain length in these mushroom NR-PKSs, even though their KS domains differ in only ten amino acids. A unique proline-rich linker connecting the acyl carrier protein with the thioesterase domain varies most between these two enzymes but is not involved in chain length control.     

Improved Synthesis of Buprenorphine from Thebaine and/or Oripavine via Palladium‐Catalyzed N‐Demethylation/Acylation and/or Concomitant O‐Demethylation

An improved preparation of buprenorphine via palladium‐catalyzed N‐demethylation/acylation is reported. Three routes were investigated and compared in overall yield. The first involved N‐demethylation/acylation of an advanced intermediate obtained from thebaine followed by hydrolysis of the N‐acetamide and alkylation with cyclopropylmethyl bromide and/or reduction of the N‐acetyl group with the Schwartz reagent followed by N‐alkylation. The second route employed cyclopropylcarboxylic acid anhydride in the N‐demethylation/acylation protocol and subsequent reduction of the cyclopropylcarboxamide by either lithium aluminum hydride or under hydrosilylation conditions. Both of these routes originated in thebaine and therefore required O‐demethylation as a final step. The third route employed an N‐demethylation/acylation sequence starting from oripavine rather than thebaine, thus avoiding the O‐demethylation. The routes are compared for overall efficiency and experimental and spectral data are provided for all new compounds.     

A steady state solver for modelling rotating electromechanical devices exploiting the transformation from time to position domain

The paper presents a study on a novel steady state solver for modelling rotating electromechanical devices. As the new contribution, the transformation of the system from time to position domain is exploited to improve the efficiency of computation. The proposed methodology is well suited to optimizing the current or voltage waveforms to drive the system with an imposed reference torque. To illustrate the technique, a brushless direct current motor is considered. Copyright © 2013 John Wiley & Sons, Ltd.     

New approaches for brazing temperature sensitive materials

PVD deposited copper interlayers as filler materials were used in order to manufacture TLP brazed magnesium joints. The microstructure and interface characteristics of the overlap joints were investigated by optical microscopy, scanning electron microscope with energy dispersive spectrometer and tensile testing. Sound brazed joints could be achieved. The dwell time is the main factor to control the thickness of the reaction layer. It was shown that the deposited copper filler metal clearly reacted with the magnesium substrate , resulting in the formation of a magnesium solid solution （Mg） with different amount of copper, aluminum and zinc as well as Mg2Cu phases. With the progressing diffusion, the formation of intermetaUic compounds was suppressed and the hardness distribution in the brazing seam homogenized. The joints fractured at the interface, and the maximum average tensile shear strength of overlap joints reached 85 MPa.     

Optimizing the Power Production in an Osmotic Engine via Microfluidic Fabricated and Surface Crosslinked Hydrogels Utilizing Fresh and Salt Water

Salinity gradients between seawater and river water is a renewable source of energy having a worldwide potential capacity of about 3.1 TW. This energy can be extracted by e.g., an osmotic engine, using hydrogels with high water uptake capacity. Consecutive exposing hydrogels to fresh and saline water makes swelling–shrinking cycles, which can be utilized to move a piston in an osmotic engine. The production of power with this method is significantly suppressed by gelblocking, where voids between particles are blocked so that the water flow is limited and the absorbency significantly retarded. To improve the power production, the gelblocking is minimized within this article by using spherical mono‐dispersed hydrogels made by microfluidic technique. In this study mono‐disperse poly(acrylic acid‐co‐sodium acrylate) hydrogels with varying diameters (100‐600 µm) and varying degrees of neutralization (DN = 10–75 mol%) are synthesized. In addition, hydrogels with different DN are utilized for additional surface crosslinking to fabricate core–shell particles. The maximum power of 0.67 W kg^?1 is obtained for hydrogels with a diameter of 105 µm, degree of crosslinking (DC) = 1.7 mol%, DN = 75 mol%, and a core‐shell architecture, which is three times higher compared to hydrogels having undefined size without a core–shell framework.     

Nanostructured conformal hybrid solar cells: a promising architecture towards complete charge collection and light absorption

We introduce hybrid solar cells with an architecture consisting of an electrodeposited ZnO nanorod array (NRA) coated with a conformal thin layer (<50 nm) of organic polymer-fullerene blend and a quasi-conformal Ag top contact (Thin/NR). We have compared the performance of Thin/NR cells to conventional hybrid cells in which the same NRAs are completely filled with organic blend (Thick/NR). The Thin/NR design absorbs at least as much light as Thick/NR cells, while charge extraction is significantly enhanced due to the proximity of the electrodes, resulting in a higher current density per unit volume of blend and improved power conversion efficiency. The NRAs need not be periodic or aligned and hence can be made very simply.     

Magnetoelectricity in CoFe2O4 nanocrystal-P(VDF-HFP) thin films

Transition metal ferrites such as CoFe₂O₄, possessing a large magnetostriction coefficient and high Curie temperature (T_c > 600 K), are excellent candidates for creating magnetic order at the nanoscale and provide a pathway to the fabrication of uniform particle-matrix films with optimized potential for magnetoelectric coupling. Here, a series of 0–3 type nanocomposite thin films composed of ferrimagnetic cobalt ferrite nanocrystals (8 to 18 nm) and a ferroelectric/piezoelectric polymer poly(vinylidene fluoride-co-hexafluoropropene), P(VDF-HFP), were prepared by multiple spin coating and cast coating over a thickness range of 200 nm to 1.6 μm. We describe the synthesis and structural characterization of the nanocrystals and composite films by XRD, TEM, HRTEM, STEM, and SEM, as well as dielectric and magnetic properties, in order to identify evidence of cooperative interactions between the two phases. The CoFe₂O₄ polymer nanocomposite thin films exhibit composition-dependent effective permittivity, loss tangent, and specific saturation magnetization (M_s). An enhancement of the effective permittivity and saturation magnetization of the CoFe₂O₄-P(VDF-HFP) films was observed and directly compared with CoFe₂O₄-polyvinylpyrrolidone, a non-ferroelectric polymer-based nanocomposite prepared by the same method. The comparison provided evidence for the observation of a magnetoelectric effect in the case of CoFe₂O₄-P(VDF-HFP), attributed to a magnetostrictive/piezoelectric interaction. An enhancement of M_s up to +20.7% was observed at room temperature in the case of the 10 wt.% CoFe₂O₄-P(VDF-HFP) sample.     

Compressibility of porous TiO2 nanoparticle coating on paperboard

Compressibility of liquid flame spray-deposited porous TiO₂ nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO₂ nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure.

PACS

61.46.-w; 68.08.Bc; 81.07.-b