Phonon polaritons are promising for infrared applications due to a strong light-matter coupling and subwavelength energy confinement they offer. Yet, the spectral narrowness of the phonon bands and difficulty to tune the phonon polariton properties hinder further progress in this field. SrTiO - a prototype perovskite oxide - has recently attracted attention due to two prominent far-infrared phonon polaritons bands, albeit without any tuning reported so far.
View Article and Find Full Text PDFOptical terahertz technology has, despite its exciting properties, such as transparency of visibly opaque materials, 30 years after its technological breakthrough, not found a widespread application with societal relevance. Main causes are its maturity and costs. If, however, the uniqueness of both THz radiation and time-domain spectroscopy is used to close a technological gap in the right market sector, we here show that successful applications are in reach.
View Article and Find Full Text PDF2,4-Diamino-2,4,6-trideoxyglucose (bacillosamine) is a monosaccharide found in many pathogenic bacteria, variation in the functionalities appended to the amino groups occurs depending on the species the sugar is derived from. We here report the first synthesis of bacillosamine synthons that allow for the incorporation of two different functionalities at the C-2-N-acetyl and C-4-amines. We have developed chemistry to assemble a set of conjugation ready Neisseria meningitidis C-2-N-acetyl bacillosamine saccharides, carrying either an acetyl or (R)- or (S)-glyceroyl at the C-4 amine.
View Article and Find Full Text PDFThis case report presents the case of a 29 weeks pregnant woman in her late twenties who was seen at the emergency department of a hospital with a seizure of unknown cause. By anamnesis and hetero-anamnesis the use of illicit gamma-hydroxybutyric acid (GHB) was revealed. Examination showed dilated pupils, sweating, tremor, tachycardia and bradyphrenic thinking.
View Article and Find Full Text PDFParacetamol [N-(4-hydroxyphenyl)acetamide, CHNO] has several polymorphs, just like many other drugs. The most stable polymorphs, denoted Forms I and II, can be obtained easily and their crystal structures are known. Crystals of the orthorhombic, less stable, room-temperature Form III are difficult to grow; they need a special recipe to crystallize and suffer from severe preferred orientation.
View Article and Find Full Text PDFThe development of effective protecting group chemistry is an important driving force behind the progress in the synthesis of complex oligosaccharides. Automated solid-phase synthesis is an attractive technique for the rapid assembly of oligosaccharides, built up of repetitive elements. The fact that (harsh) reagents are used in excess in multiple reaction cycles makes this technique extra demanding on the protecting groups used.
View Article and Find Full Text PDFBackground: People with severe mental illness show high rates of unemployment and work disability, however, they often have a desire to participate in employment. People with severe mental illness used to be placed in sheltered employment or were enrolled in prevocational training to facilitate transition to a competitive job. Now, there are also interventions focusing on rapid search for a competitive job, with ongoing support to keep the job, known as supported employment.
View Article and Find Full Text PDFWe present an optical study that reveals the bulk dynamics of the stratification process in drying colloidal dispersions. Terahertz time-domain spectroscopy has been used to measure in situ solventborne and waterborne paint layers as a function of drying time. The dynamic behavior of the dry top layer and wet bottom layer thickness, as well as the bulk thickness, reflect the principal processes of the established drying mechanism.
View Article and Find Full Text PDFWe propose a novel terahertz material analysis approach that provides highly accurate material parameters and can be used for industrial quality control. The method treats the inspected material within its environment locally as a stratified system and describes the light-matter interaction of each layer in a realistic way. The approach is illustrated in the time-domain and frequency-domain for two potential fields of implementation of terahertz technology: quality control of (coated) paper sheets and car paint multilayers, both measured in humid air.
View Article and Find Full Text PDFThe terahertz (THz) excitations in the quantum spin-ladder system Sr14Cu24O41 have been determined along the c axis using THz time-domain, Raman, and infrared spectroscopy. Low-frequency infrared and Raman active modes are observed above and below the charge-ordering temperature T(co) is approximately equal to 200 K over a narrow interval approximately equal to 1-2 meV approximately equal to 8-16 cm(-1)). A new infrared mode at approximately equal to 1 meV develops below approximately equal to 100 K.
View Article and Find Full Text PDFWe present a magneto-optical study of the three-dimensional topological insulator, strained HgTe, using a technique which capitalizes on advantages of time-domain spectroscopy to amplify the signal from the surface states. This measurement delivers valuable and precise information regarding the surface-state dispersion within <1 meV of the Fermi level. The technique is highly suitable for the pursuit of the topological magnetoelectric effect and axion electrodynamics.
View Article and Find Full Text PDFWe show an example of a purely magnetic spin resonance in EuTiO(3) and the resulting new record high Faraday rotation of 590°/mm at 1.6 T for 1 cm wavelengths probed by a novel technique of magneto-optical gigahertz time-domain ellipsometry. From our transmission measurements of linear polarized light, we map out the complex index of refraction n=√ϵμ in the gigahertz to terahertz range.
View Article and Find Full Text PDFThe lipid matrix present in the uppermost layer of the skin, the stratum corneum, plays a crucial role in the skin barrier function. The lipids are organized into two lamellar phases. To gain more insight into the molecular organization of one of these lamellar phases, we performed neutron diffraction studies.
View Article and Find Full Text PDFThe crystal structures of the beta'(1)-2, the beta'-3 and the beta(2)-3 polymorphs of 1,3-dilauroyl-2-oleoylglycerol have been solved from powder diffraction data. The packing of the beta(2)-3 polymorph is similar to that of other cis mono-unsaturated triacylglycerols. Both the beta' polymorphs are crystallized in a novel type of packing in which one of the saturated lauroyl chains is packed side-by-side with part of the unsaturated oleoyl chain.
View Article and Find Full Text PDFWe report a comprehensive THz, infrared and optical study of Nb-doped SrTiO3 as well as dc conductivity and Hall effect measurements. Our THz spectra at 7 K show the presence of an unusually narrow (<2 meV) Drude peak. For all carrier concentrations the Drude spectral weight shows a factor of three mass enhancement relative to the effective mass in the local density approximation, whereas the spectral weight contained in the incoherent midinfrared response indicates that the mass enhancement is at least a factor two.
View Article and Find Full Text PDFThe beta'(1)-2 crystal structures of a series of mixed-chain saturated and trans-mono-unsaturated triacylglycerols containing palmitoyl, stearoyl and elaidoyl acyl chains have been solved from high-resolution powder diffraction data, from synchrotron as well as laboratory X-ray sources. The structures crystallized in the space group I2 with two independent molecules forming a dimer in the asymmetric unit, and packed in double-chain length layers. Unlike the corresponding beta-2 structures the solved beta'(1)-2 structures have different molecular conformations for the symmetric and the asymmetric mixed triacylglycerols, both with the sn-2 chain in a leg position of the chair-shaped conformation.
View Article and Find Full Text PDFThe beta-2 crystal structures of a series of saturated and trans-mono-unsaturated triacylglycerols (TAGs) have been solved from high-resolution powder synchrotron diffraction data. The series comprises symmetric as well as asymmetric even-numbered TAGs and the trans-mono-unsaturated ones all have a single elaidoyl chain. The structures have been solved with the direct-space parallel-tempering program FOX and refined with the Rietveld program GSAS.
View Article and Find Full Text PDFActa Crystallogr B
December 2006
An improved crystal structure model has been established for the beta2 polymorph of the symmetric mono-unsaturated triacylglycerol 1,3-distearoyl-2-oleoylglycerol (SOS) and the equivalent beta-V polymorph of Ivory Coast cocoa butter. In addition, the crystal structures of the beta2 polymorphs are reported for the triacylglycerols 1,3-dipalmitoyl-2-oleoylglycerol (POP) and 1-palmitoyl-2-oleoyl-3-stearoylglycerol (POS), which are, together with SOS, the major components of cocoa butter, and that of 1-stearoyl-2-oleoyl-3-arachidoylglycerol (SOA). The existence of beta2-POS and beta2-SOA has not been previously reported in the literature.
View Article and Find Full Text PDFActa Crystallogr B
December 2006
The crystal structures of the beta1 polymorphs of mono-unsaturated triacylglycerols have been solved from high-resolution laboratory and synchrotron powder diffraction data for five pure compounds, the 1,3-dimyristoyl-2-oleoylglycerol (beta1-MOM), 1,3-dipalmitoyl-2-oleoylglycerol (beta1-POP), 1,3-distearoyl-2-oleoylglycerol (beta1-SOS), 1-palmitoyl-2-oleoyl-3-stearoylglycerol (beta1-POS), 1-stearoyl-2-oleoyl-3-arachidoylglycerol (beta1-SOA) and three mixtures: the co-crystallized 1:1 molar mixture of SOS and POP [beta1-SOS/POP (1:1)] and two cocoa butters from Bahia and Ivory Coast, both in their beta-VI (=beta1) polymorph. All eight beta1 structures crystallized in the space group (P2(1)/n) and have two short cell axes (5.44-5.
View Article and Find Full Text PDFTwo full-length lipoxygenase cDNA sequences (LoxB and LoxC) from barley (Hordeum distichum cv. L. Triumph) are described.
View Article and Find Full Text PDFThe barley lipoxygenase 1 (Lox1) gene encodes a protein expressed in embryos during grain development and germination and in leaves after methyl-jasmonate (MeJA) treatment. Transient gene expression assays in germinating barley embryos were used to identify cis-regulatory elements involved in the embryo-specific expression of the Lox1 gene. Analysis of transcriptional or translational fusions between Lox1 5' upstream sequences and the gusA reporter gene indicated that the 5'-untranslated leader sequence was involved in embryo-specific expression.
View Article and Find Full Text PDFBiochim Biophys Acta
January 1995
A full length cDNA sequence for a barley grain lipoxygenase was obtained. It includes a 5' untranslated region of 69 nucleotides, an open reading frame of 2586 nucleotides encoding a protein of 862 amino acid residues and a 3' untranslated region of 142 nucleotides. The molecular mass of the encoded polypeptide was calculated to be 96.
View Article and Find Full Text PDFVet Immunol Immunopathol
June 1986
Aeromonas salmonicida is a significant bacterial pathogen of cyprinid and salmonid fishes causing the systemic disease furunculosis. Several observations led us to believe that A. salmonicida was able to evade or suppress the immune system of the fish: injection of whole bacteria or surface antigens was unsuccessful at protecting fish against lethal challenges; memory did not develop in survivors of sublethal infections; diseased fish often carried other opportunistic bacterial pathogens in addition to A.
View Article and Find Full Text PDFBiochim Biophys Acta
November 1985
The role of specific amino acid residues of the K88ab and K99 fibrillar adhesins in the binding to erythrocytes and antibodies has been studied by chemical modification. It appeared that: (1) The integrity of the single disulfide bridge in the K99 subunits is essential for the binding of the fibrillae to the glycolipid receptors, but not for the recognition and binding of specific anti-K99 antibodies. (2) Modification of one lysine residue per subunit with 4-chloro-3,5-dinitrobenzoate results in the loss of the adhesive capacity of K99 fibrillae.
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