Fabrication of three-dimensional photonic crystals with tunable photonic properties by biotemplating

Photonic crystals with tunable D-surface structures for possible high-temperature gas- and temperature-sensing applications were prepared by a biotemplating method. This included infiltrating colored scales of the beetle Entimus imperialis with an organopolysiloxane mixture followed by simultaneous combustion of the template and calcination of the cured organopolysiloxane. A high-yield inorganic silica-based replica of the original structure was obtained, which is capable of withstanding temperatures up to 600 °C. Light- and scanning electron microscopy combined with focused ion beam milling showed a precise replication of the whole scales and their internal D-surface structure. Fourier-transform infrared spectroscopy and X-ray diffraction analysis confirmed the complete curing of the organopolysiloxanes and their transformation into amorphous silica during calcination. The dielectric constant of the manufactured materials determined by Abbé refractometry was ? = 2.3180 and used to perform band structure calculations utilizing the plane wave expansion method. By changing the chain length and degree of crosslinking of the organopolysiloxane precursor mixture, the lattice parameters and filling factors, and therefore the photonic properties of the replicas, could be tuned.     

R?ntgenstruktur-Analyse von Trans-1-ethyl-2-(1-ethyl-2-adamantyliden)adamantan, Vergleich mit Kraftfeld-Rechnungen

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X-ray structural analysis of trans-1-Ethyl-2-(1-ethyl-2-adamantylidene)-adamantane. Comparison with force field calculations

     

Biogene Polymere als Template

The presented bioinspired materials fabrication approach is focused on the development of innovative structural and functional materials. A key area in this innovative field of fundamental and applied research is the use or formation of biogenic (biopolymeric) structures and their conversion into composite materials for engineering and biomedical applications. The fundamental chemical and physical transformation processes involved in these conversions are demonstrated on selected examples.     

Dry,hydrophobic microfibrillated cellulose powder obtained in a simple procedure using alkyl ketene dimer

In order to produce dry and hydrophobic microfibrillated cellulose (MFC) in a simple procedure, its modification with alkyl ketene dimer (AKD) was performed. For this purpose, MFC was solvent-exchanged to ethyl acetate and mixed with AKD dissolved in the same solvent. Curing at 130 °C for 20 h under the catalysis of 1-methylimidazole yielded a dry powder. Scanning electron microscopy of the powder indicated loss in nanofibrillar structure due to aggregation, but discrete microfibrillar structures were still present. Water contact angle measurements of films produced from modified and unmodified MFC showed high hydrophobicity after AKD treatment, which persisted even after extraction with THF for 8 h. The hydrophobized MFC was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance and X-ray analysis. In summary, strong indications for the presence of AKD on the surface of MFC before and after extraction with solvent were found, but only a very small amount of covalent β-ketoester linkages between the modification agent and cellulose was revealed.     

Control-It. - A new software concept to control isotope mass spectrometers and preparation lines

A new software, CONTROL-IT, was developed as an easy means to control isotope mass spectrometers and automated sample preparation lines by the user himself. CONTROL-IT makes thoroughly use of the graphical human interface on Apple Macintosh® systems and is written for the Hypercard® environment. Control of the isotope-analytical hardware bases on software procedures passed by name to a do-list which in the automated control mode is evaluated consecutively. CONTROL-IT enables the user to set up the control sequence in all detail himself and lets him readily modify and update his preparation and measuring routines for precise adaption to the analytical demands, experimental evidence, or new developments of his hardware. A schematic representation of the isotope-analytical hardware, composed of interactive icons of the hardware elements, makes the software almost completely screen-operated and provides high flexibility and transparency to the user for interactive assembling of the control sequence as well as for half-automated or full-hand operation of the hardware system or parts of it. - In Kiel, CONTROL-IT is applied to a Delta E spectrometer, an equilibration unit for δ¹⁸O analysis on water samples, and a multiport for external gas samples.     

BIOTECON diagnostics foodproof Listeria monocytogenes Detection Kit, 5' nuclease in combination with the foodproof ShortPrep II Kit

A method was developed for the detection of Listeria monocytogenes in food. The method is based on real-time PCR using hydrolysis probes (5' Nuclease). This advanced PCR method was designed to reduce the time necessary to achieve results from PCR reactions and to enable the user to monitor the amplification of the PCR product simultaneously, in real-time. After DNA isolation using the BIOTECON foodproof ShortPrep II Kit designed for the rapid preparation of L. monocytogenes DNA for direct use in PCR, the real-time detection of L. monocytogenes DNA is carried out using the foodproof Listeria monocytogenes Detection Kit. The kit provides primers and hydrolysis probes for sequence-specific detection, convenient premixed reagents, and controls for reliable interpretation of results. For the internal comparison study, three different foods (soft cheese, coalfish, and smoked ham) were analyzed, chosen from the 15 food groups recommended by the AOAC Research Institute for detection of L. monocytogenes. From each food, 20 samples were inoculated with a low level (1-10 CFU/25 g) and 20 samples with a high level (10-50 CFU/25 g) of L. monocytogenes. Additionally, five nonspiked samples were prepared from each food. Depending on the matrix, the food samples were examined with the test kits and compared with the cultural methods according to the U.S. Food and Drug Administration's Bacteriological Analytical Manual or the U.S. Department of Agriculture/Food Safety and Inspection Service Microbiology Laboratory Guidebook.     

Thermodynamics of mixing of ethylene oxide oligomers with different end groups in tetrachloromethane: theoretical treatment

In a previous paper we reported the enthalpies of mixing of oligomers of ethylene oxide with different end groups in tetrachloromethane. This paper shows the applicability of the modified theoretical treatment, based on a quasichemical equilibrium of the contacting segmental surfaces originated from Huggins, to our experimental results. The experimental data of ethylene oxide oligomers with methoxy end groups can be described with the energy parameter Δε_αβ, the equilibrium constant K_αβ and the surface ratio r_σ assuming a chemically uniform surface of the oligomer in CCI₄. Ethylene oxides with strong polar OH end groups can be treated successfully with an extended version of the theory with two additional parameters K and ΔΔε for systems containing three different kinds of chemical units.     

Development of a qualitative, multiplex real-time PCR kit for screening of genetically modified organisms (GMOs)

The number of commercially available genetically modified organisms (GMOs) and therefore the diversity of possible target sequences for molecular detection techniques are constantly increasing. As a result, GMO laboratories and the food production industry currently are forced to apply many different methods to reliably test raw material and complex processed food products. Screening methods have become more and more relevant to minimize the analytical effort and to make a preselection for further analysis (e.g., specific identification or quantification of the GMO). A multiplex real-time PCR kit was developed to detect the 35S promoter of the cauliflower mosaic virus, the terminator of the nopaline synthase gene of Agrobacterium tumefaciens, the 35S promoter from the figwort mosaic virus, and the bar gene of the soil bacterium Streptomyces hygroscopicus as the most widely used sequences in GMOs. The kit contains a second assay for the detection of plant-derived DNA to control the quality of the often processed and refined sample material. Additionally, the plant-specific assay comprises a homologous internal amplification control for inhibition control. The determined limits of detection for the five assays were 10 target copies/reaction. No amplification products were observed with DNAs of 26 bacterial species, 25 yeasts, 13 molds, and 41 not genetically modified plants. The specificity of the assays was further demonstrated to be 100% by the specific amplification of DNA derived from reference material from 22 genetically modified crops. The applicability of the kit in routine laboratory use was verified by testing of 50 spiked and unspiked food products. The herein described kit represents a simple and sensitive GMO screening method for the reliable detection of multiple GMO-specific target sequences in a multiplex real-time PCR reaction.