Synthese von substituierten benzotriazolen zur stabilisierung aromatischer polyamide gegen UV-licht

2-(2′-Hydroxyphenyl)-benzotriazoles, containing a carbonamide group in 5- or 5′-position, were synthesized to stabilize polyamides. The influence of the ortho-positioned hydroxy group for the stabilizing effect of these substances was examined by methylating it. The synthesized benzotriazoles were characterized, especially with regard to their UV-absorption-spectra. The photolytic resistance of poly-(m-phenyleneisophthalamide), containing these stabilizers, for example 2-(2′-hydroxy-5′-tert-butylphenyl)-benzotriazol-5-carbonic acid anilide, was examined by measuring the viscosity.     

Salmonella contamination in pigs at slaughter and on the farm: a field study using an antibody ELISA test and a PCR technique

An antibody ELISA test and a PCR method for identifying the risk of Salmonella contamination were compared in a field study on the same lots of animals in a slaughterhouse. The results were compared to investigations carried out on two farms with different prevalences of Salmonella antibody-positive animals. Salmonella antibody ELISA testing was carried out on all 383 meat juice samples derived from the diaphragm pillar muscle of each pig. Salmonella DNA analysis was performed by PCR technique on small intestine samples with lymph nodes from all 383 pigs, and on tonsils from the last 129 pigs. The 383 animals tested came from 32 different pig farms. Furthermore, the herd antibody blood serum status against Salmonella spp. of weaners was determined on two selected pig fattening farms, one with low and one with high seroprevalence in meat juice. A total of 7.0% (ELISA cut-off OD% > or =40) of the slaughtered pigs from 6 of 32 fattening farms were seropositive. Salmonella DNA was found in 16.4% of the jejunum/lymph nodes (383 animals) and in 15.5% of the tonsils (129 animals). Salmonella DNA was found in the jejunum/lymph nodes of 41% of the seropositive pigs. However, serotitres were also positive in only 17.5% of all pigs positive in the jejunum DNA test. Two farms were selected for further investigation: farm 13 (F13), with a high prevalence of seropositive pigs, 29.0%, Category II; and F11, with 9.4%, Category I. However, categorization according to the blood serum tests of the fattening pigs after on-farm testing was very different: F13 had 5% positive animals (Category I); and F11, 23.3% (Category II). The study led to the following results and recommendations: First, ELISA tests are useful for the detection of farms that are regularly contaminated with Salmonella, but such tests cannot give information on the infectious status of a single animal (or a group) at the point of slaughter. Second, it is crucial that management measures are taken to prevent the spread of infections by trade and transport: piglets should be supplied exclusively by a single, well-known producer, and finishers should be tested serologically on farm before going to slaughter. Third, ELISA tests and the PCR method are suitable for the detection of Salmonella and are recommended as analytical tools for all pork quality control programmes. Fourth, animals from suspicious farms should always be slaughtered at the end of the slaughter day, followed by thorough cleaning and disinfection.     

A ¹⁸F-labeled fluorobutyl-substituted spirocyclic piperidine derivative as a selective radioligand for PET Imaging of sigma₁ receptors

In this study, we synthesized and evaluated a new spirocyclic piperidine derivative 3 , containing a 4‐fluorobutyl side chain, as a PET radioligand for neuroimaging of σ₁ receptors. In vitro, compound 3 displayed high affinity for σ₁ receptors (K_i=1.2 nM ) as well as high selectivity. [¹⁸F] 3 radiosynthesis was performed from the corresponding tosylate precursor, with high radiochemical yield (45–51 %), purity (>98 %), and specific activity (>201 GBq μmol^?1). Metabolic stability of [¹⁸F] 3 in the brain of CD‐1 mice was verified, and no penetration of peripheral radiometabolites into the cerebral tissue was observed. Results of ex vivo autoradiography revealed that the distribution of [¹⁸F] 3 in the brain corresponded to regions with high σ₁ receptor density. The highest region‐specific total‐to‐nonspecific ratio was determined in the facial nucleus (4.00). Biodistribution studies indicated rapid and high levels in brain uptake of [¹⁸F] 3 (2.2 % ID per gram at 5 min p.i.). Pre‐administration of haloperidol significantly inhibited [¹⁸F] 3 uptake into the brain and σ₁ receptor‐expressing organs, further confirming in vivo target specificity.     

Prediction of pyrolysis of pistachio shells based on its components hemicellulose, cellulose and lignin

The objective of this contribution is to describe thermal degradation of pistachio shells by a detailed reaction mechanism. Pistachio shells are assumed to be composed of hemicellulose, cellulose and lignin of which degradation is described by relevant kinetics based on experimental data. The mechanism yields a detailed composition of product gases, and therefore, is well-suited to predict evolution of both thermal decomposition and products. Thermal degradation is described by a system of coupled differential conservation equations for mass, momentum, species, and energy for a pistachio shell particle. The relevant conservation equations are discretised by the Finite Volume Method (FVM) and solved within the conversion module of the Discrete Particle Method (DPM). A comparison between experimental data and predicted results yielded good agreement.     

Determination of hemin-binding characteristics of proteins by a combinatorial peptide library approach

Studies of the binding of heme/hemin to proteins or peptides have recently intensified as it became evident that heme serves not only as a prosthetic group, but also as a regulator and effector molecule interacting with transmembrane and cytoplasmic proteins. The iron‐ion‐containing heme group can associate with these proteins in different ways, with the amino acids Cys, His, and Tyr allowing individual modes of binding. Strong coordinate‐covalent binding, such as in cytochrome c, is known, and reversible attachment is also discussed. Ligands for both types of binding have been reported independently, though sometimes with different affinities for similar sequences. We applied a combinatorial approach using the library (X)₄(C/H/Y)(X)₄ to characterize peptide ligands with considerable hemin binding capacities. Some of the library‐selected peptides were comparable in terms of hemin association independently of whether or not a cysteine residue was present in the sequence. Indeed, a preference for His‐based (≈39 %) and Tyr‐based (≈40 %) sequences over Cys‐based ones (≈21 %) was detected. The binding affinities for the library‐selected peptides, as determined by UV/Vis spectroscopy, were in the nanomolar range. Moreover, selected representatives efficiently competed for hemin binding with the human BK channel hSlo1, which is known to be regulated by heme through binding to its heme‐binding domain.     

Kinetics of nucleation and crystallization in poly(?-caprolactone) (PCL)

The recently developed differential fast scanning calorimetry (DFSC) is used for a new look at the crystal growth of poly(?-caprolactone) (PCL) from 185 K, below the glass transition temperature, to 330 K, close to the equilibrium melting temperature. The DFSC allows temperature control of the sample and determination of its heat capacity using heating rates from 50 to 50,000 K/s. The crystal nucleation and crystallization halftimes were determined simultaneously. The obtained halftimes cover a range from 3 × 10⁻² s (nucleation at 215 K) to 3 × 10⁹ s (crystallization at 185 K). After attempting to analyze the experiments with the classical nucleation and growth model, developed for systems consisting of small molecules, a new methodology is described which addresses the specific problems of crystallization of flexible linear macromolecules. The key problems which are attempted to be resolved concern the differences between the structures of the various entities identified and their specific role in the mechanism of growth. The structures range from configurations having practically unmeasurable latent heats of ordering (nuclei) to being clearly-recognizable, ordered species with rather sharp disordering endotherms in the temperature range from the glass transition to equilibrium melting for increasingly perfect and larger crystals. The mechanisms and kinetics of growth involve also a detailed understanding of the interaction with the surrounding rigid-amorphous fraction (RAF) in dependence of crystal size and perfection.     

Development of a Ag/Ag micro-reference electrode for electrochemical measurements in ionic liquids

We report on a novel miniaturized Ag/Ag⁺ reference electrode (RE) design suitable for electrochemical measurements in room temperature ionic liquids (RTILs). The electrode is based on capillaries with an outer diameter of 365 μm and contains a 10 mmol/l solution of a silver salt in a RTIL. The silver salt bears the same type of anion as the RTIL. While potential shifts of several hundred millivolts have been observed for common platinum or silver pseudo-reference electrodes, our Ag/Ag⁺ micro electrode provides a stable and reliable reference potential over a period of more than two weeks, if protected from light and stored in a nitrogen atmosphere. Due to the small dimensions of the RE, it can be placed close to the working electrode (WE) and it is well-suited for application in electrochemical micro cells as well as for potential-controlled in situ AFM, STM or electrochemical impedance measurements. The electrode characteristics were determined by voltammetric measurements on ferrocene and cobaltocenium hexafluorophosphate dissolved in a RTIL. The highest expected contamination of the sample with Ag⁺ ions was calculated and found to be below 4 ppm.     

Abwasserreinigung mit Schilf in einer mobilen Wurzelraumkläranlage

A mobile root‐zone wastewater treatment system with a reaction zone consisting solely of reed roots as the growth surface for microorganisms was tested for temporary applications in the treatment of municipal wastewater. Pretreated municipal wastewater from a large‐scale wastewater treatment plant was fed to this system during the 2016 vegetation period. The outlet limit values for chemical oxygen demand and biochemical oxygen demand were adhered to reliably at an inlet volumetric flow rate of 1200 L d^?1. Short‐term loading peaks of up to 1800 L d^?1 did not lead to overloading of the system.     

Switchable Plasmonic Metasurface Utilizing the Electro-Optic Kerr Effect of a Blue Phase Liquid Crystal

A switchable metasurface composed of plasmonic split ring resonators and a polymer-stabilized liquid crystal blue phase is developed. Owing to field-induced birefringence (electro-optic Kerr effect), the state of polarization of the incident near infrared radiation changes, when a voltage is applied to the liquid crystal. Thus, different resonant modes of the split ring resonators can be addressed and the transmission spectrum changes accordingly. In comparison with other liquid crystal phases, blue phases have several advantages. For example, they are optically isotropic in the field-off state, so that no alignment layer is required. The results of the present study indicate that the advantages of these mesophases can be utilized for switchable metasurfaces.     

Viscosity‐molecular weight relationship for cellulose solutions in either NMMO monohydrate or cuen

The intrinsic viscosities, [η], of nine cellulose samples, with molar masses from 50 × 10³ to 1 390 × 10³ were determined in the solvents NMMO*H₂O (N‐methyl morpholin N‐oxide hydrate) at 80°C and in cuen (copper II‐ethlenediamine) at 25°C. The evaluation of these results with respect to the Kuhn–Mark–Houwink relations shows that the data for NMMO*H₂O fall on the usual straight line in the double logarithmic plots only for M ≤ 158 10³; the corresponding [η]/M relation reads log ([η]/mL g⁻¹) = –1.465 + 0.735 log M. Beyond that molar mass [η] remains almost constant up to M ≈ 10⁶ and increases again thereafter. In contrast to NMMO*H₂O the cellulose solutions in cuen behave normal and the Kuhn–Mark–Houwink relation reads log ([η]/mL g⁻¹) = −1.185 + 0.735 log M. Possible reasons for the dissimilarities of the behavior of cellulose in these two solvents are being discussed. The comparison of three different methods for the determination of [η] from viscosity measurements at different polymer concentrations, c, demonstrates the advantages of plotting the natural logarithm of the relative viscosities as a function of c. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011