A study of Nd2Fe14B and a neodymium-rich phase in sintered NdFeB magnets

The microstructure and properties of NdFeB sintered permanent magnets were analysed by different methods. Samples analysed were sintered and thermally treated. The hard magnetic Nd₂Fe₁₄B phase and amorphous neodymium-rich phase were observed by TEM. The neodymium-rich phase contained iron and boron, in elemental and in B₂O₃ form, which is known as a glass former. At the sintering temperature, Nd₂Fe₁₄B and the neodymium-rich phase are supersaturated with iron, which should be dissolved at the annealing temperature to react with neodymium and boron and form additional Nd₂Fe₁₄B phase. Iron precipitates of size up to 2 nm were detected in the Nd₂Fe₁₄B phase. These superparamagnetic precipitates of -Fe could affect the hard magnetic properties of NdFeB magnets.     

Carcass traits and meat quality of male lambs fed monensin or lasalocid

Male lambs, crossbred Merino × Ille de France, were fed a diet supplemented with 31 mg monensin or 32 mg lasalocid per kg of feed dry matter from an initial body weight of 23·6–23·9 kg to the slaughter weight of approximately 40 kg.

Carcass traits and meat quality were evaluated after slaughter; the values obtained were compared with those of the control group fed the same diet without the ionophore supplement.

There were few significant differences among the individual groups in carcass value, sensoric and technological properties of meat and of its composition. However, the lasalocid-fed group seemed to be somewhat better in muscling and in the composition of meat.     

Identification and changes in the higher fatty acids of dried red pepper and red pepper powder

Summary The higher fatty acids of dried red pepper of the variety of Gorogled were identified by gas chromatography with using help of authentic compounds. Their amounts were determined using on absolute calibration method.The following acids were established: lauric, myrastic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic,arachidic and behenic acids. The results obtained from the quantitative measurements showed that linoleic, linolenic and palmitic acids amounted to 80% of the total acids.The quantitative changes of identified acids in red pepper, of dried at 60°, 70°, 80° and 90 °C red pepper and stored as dried red pepper and red pepper powder over a 6-months period investigated.The results show that under the drying temperatures applied the amount of all fatty acids decreased with an increase in the temperature. During a storage a period of 3 months the amount of the respective acids decreased while the process was the most expressed in red pepper dried at a temperature of t = 70 °C.After a 6-months storage period under the drying condition applied the dried red pepper contained a greater amount of fatty acids compared with stored for 3 months.

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Identifikation und Veränderungen der höheren Fettsäuren von gemahlenem Paprika und von getrockneten ungemahlenen Paprikaschoten

Zusammenfassung Es wurden gaschromatographisch mit Hilfe von Vergleichsubstanzen die höheren Fettsäuren, die im gemahlenen Paprika (Sorte Gorogled) enthalten sind, identifiziert. Die Mengen wurden nach der Methode der absoluten Kalibrierung bestimmt. Es wurden folgende Säuren festgestellt: Laurinsäure, Myristin-, Palmitin-, Palmitoolein-, Stearin-, Olein-, Linol-, Linolen-, Arachin- und Behensäure. Die quantitativen Ergebnisse zeigen, daß die Menge der Linolen-, Linol- und Palmitinsäure 80% der Gesamtsäurenmenge darstellt. Es wurden die quantitativen Veränderungen der Fettsäuren von Paprika (Sorte Gorogled) bei Temperaturen von 60 °, 70 °, 80 ° und 90 °C, getrocknet und als getrockneter ungemahlener bzw.gemahlener Paprika, gelagert und innerhalb von 6 Monaten in Abständen von 3 Monaten verfolgt. Bei den angewendeten Trocknungstemperaturen nimmt die Menge der einzelnen Fettsäuren in dem getrockneten ungemahlenen Paprika mit Erhöhung der Trocknungstemperatur ab. Die Lagerung des getrockneten ungemahlenen Paprikas innerhalb von 3 Monaten führt zur Abnahme der einzelnen Fettsäuren, wobei dieser Prozeß am stärksten bei einer Trocknungstemperatur von 70 °C verläuft. Nach einer 6monatigen Lagerung des getrockneten und ungemahlenen Paprikas, nach Trocknung und bei den o. g. vier Temperaturen, ist die Menge der Fettsäuren höher im Vergleich zu jener der Fettsäuren in getrocknetem ungemahlenem Paprika nach 3 Monaten. Nach 3 Monaten enthält der gemahlene Paprika weniger Fettsäuren als der getrocknete und ungemahlene Paprika.

     

Thermodynamic analysis of the refining of technical boron nitride

The efficiency of the process of refining technical boron nitride was assessed based on calculations of the chemical equilibrium in the B-N-O-C-Cl-H system. Three refining mixtures, CCl₄ + H₂, CCl₄ + NH₃ and CHCl₃ + NH₃, were considered. The analysis indicates that the use of ammonia-containing mixtures is more convenient, a lower residual oxygen content, lower contamination of the product by carbon and a better overall boron balance emerging. The calculations of the equilibrium composition of the solid phase enabled suitable technological conditions of the refining process (temperature and starting composition of the gaseous phase) to be established. The calculated results are compared with experimental data, and some observed differences are discussed.     

Photo-Chemically-Deposited and Industrial Cu/ZnO/Al2O3 Catalyst Material Surface Structures During CO2 Hydrogenation to Methanol: EXAFS,XANES and XPS Analyses of Phases After Oxidation,Reduction, and Reaction

Catalysis Letters - Industrial Cu/ZnO/Al2O3 or novel rate catalysts, prepared with a photochemical deposition method, were studied under functional CH3OH synthesis conditions at the set temperature...     

Isobutylene polymerization in the presence of t-BuCl/SnCl4

Summary The effect of tert-butyl chloride in the polymerizations of isobutylene carried out in the presence of SnCl₄ in dichloromethane at temperatures-20°C and-78°C was investigated. Synthesized polyisobutylene samples showed a bimodal molecular weight distribution (MWD) and it was found that the weight content of the lowermolecular weight (LMW) fraction increased with increasing t-BuCl concentration in the polymerization mixture. The effect of ageing of the initiation mixture t-BuCl/SnCl₄ in CH₂Cl₂ prepared in advance on MWD of the PIB samples was also studied. Ageing of the initiation system supports the formation of the LMW fraction and this oily PIB is the only product of the polymerization at-20°C, .     

Effect of substrate on the risk of being washed away by floods for the Groundhoppers Tetrix subulata and Tetrix tenuicornis (Orthoptera: Tetrigidae)

Inundation zones of rivers are risky environments for terrestrial animals because of the regular or irregular occurrence of floods. Although animals in these zones have evolved several strategies to survive floods, behavioural anti‐flooding strategies have seldom been studied but could play an important role in their life history strategies. We previously reported that the groundhopper Tetrix tenuicornis moves to dense vegetation in response to low atmospheric pressure (which may signal rain and flooding) but prefers mossy microhabitats and bare ground under high atmospheric pressure. In the current study, we found that the ability of the semi‐aquatic groundhoppers T. tenuicornis and Tetrix subulata to withstand direct water flow was greater in patches of dense vegetation than in patches of moss or on bare ground. Even a relatively low water velocity led to water transport (presumably passive) of both species, perhaps because they lack arolia or other adhesive devices on their tarsi. This morphological limitation precludes vertical migration on vegetation, which is a common anti‐flooding strategy in insects. Our results suggest that, by moving to dense vegetation in response to drops in atmospheric pressure, groundhoppers may reduce their risk of being washed away by floods.     

Fault-Tolerant Formation Driving Mechanism Designed for Heterogeneous MAVs-UGVs Groups

A fault-tolerant method for stabilization and navigation of 3D heterogeneous formations is proposed in this paper. The presented Model Predictive Control (MPC) based approach enables to deploy compact formations of closely cooperating autonomous aerial and ground robots in surveillance scenarios without the necessity of a precise external localization. Instead, the proposed method relies on a top-view visual relative localization provided by the micro aerial vehicles flying above the ground robots and on a simple yet stable visual based navigation using images from an onboard monocular camera. The MPC based schema together with a fault detection and recovery mechanism provide a robust solution applicable in complex environments with static and dynamic obstacles. The core of the proposed leader-follower based formation driving method consists in a representation of the entire 3D formation as a convex hull projected along a desired path that has to be followed by the group. Such an approach provides non-collision solution and respects requirements of the direct visibility between the team members. The uninterrupted visibility is crucial for the employed top-view localization and therefore for the stabilization of the group. The proposed formation driving method and the fault recovery mechanisms are verified by simulations and hardware experiments presented in the paper.     

Mechanical properties of wollastonite‐reinforced polypropylene composites modified with SEBS and SEBS‐g‐MA elastomers

Mechanical properties of isotactic polypropylene/wollastonite/styrene rubber block copolymers (iPP/wollastonite/SRBC) composites were studied as a function of elastomeric poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) triblock copolymer (SEBS) and SEBS grafted with maleic anhydride (SEBS‐g‐MA) content from 0 to 20 vol%. Microphase morphology was stronger influenced by SRBC elastomers than by different wollastonite types. Higher encapsulation ability of SEBS‐g‐MA than SEBS caused more expressive core‐shell morphology and consequently higher notched impact strength as well as yield parameters, but lower Young's modulus. Higher ductility of the composites with SEBS than with SEBS‐g‐MA has been primarily caused by better miscibility of the polypropylene chains with SEBS molecules. Surface properties of components and adhesion parameters also indicated that adhesion at SEBS‐g‐MA/wollastonite interface, which was stronger than the one at the SEBS/wollastonite interface, influenced higher encapsulation of wollastonite particles by SEBS‐g‐MA. POLYM. ENG. SCI., 47:1873–1880, 2007. © 2007 Society of Plastics Engineers