1,356 research outputs found
Liotryphon punctulatus (Ratzeburg, 1848) (Hymenoptera: Ichneumonidae) – a parasitoid of Ephestia kuehniella larvae
Until now, there has been no record of Liotrophon punctulatus (Hymenoptera: Ichneumonidae) presence in the anthropogenic environment of mills, bakeries or pasta factories. This is the first report of the species parasitizing Ephestia kuehniella (Lepidoptera: Pyralidae) larvae. The host/parasitoid interaction was validated under laboratory conditions where fourth or fifth instar larvae of Ephestia kuehniella were provided ad libitum to L. punctulatus females. After two filial generations emergence, the validation process was considered to confirm the interaction. Keywords: Liotrophon punctulatus, Parasitoid, Ephestia kuehniell
Polyaniline. Preparation of a conducting polymer (IUPAC technical report)
Eight persons from five institutions in different countries carried out polymerizations of aniline following the same preparation protocol. In a "standard" procedure, aniline hydrochloride was oxidized with ammonium peroxydisulfate in aqueous medium at ambient temperature. The yield of polyaniline was higher than 90% in all cases. The electrical conductivity of polyaniline hydrochloride thus prepared was 4.4 1.7 S cm(-1) (average of 59 samples), measured at room temperature. A product with defined electrical properties could be obtained in various laboratories by following the same synthetic procedure. The influence of reduced reaction temperature and increased acidity of the polymerization medium on polyaniline conductivity were also addressed. The conductivity changes occurring during the storage of polyaniline were monitored. The density of polyaniline hydrochloride was 1.329 g cm(-3). The average conductivity of corresponding polyaniline bases was 1.4 x 10(-8) S cm(-1), the density being 1.245 cm(-3). Additional changes in the conductivity take place during storage. Aging is more pronounced in powders than in compressed samples. As far as aging effects are concerned, their assessment is relative. The observed reduction in the conductivity by similar to10% after more than one-year storage is large but, compared with the low conductivity of corresponding polyaniline (PANI) base, such a change is negligible. For most applications, an acceptable level of conductivity may be maintained throughout the expected lifetime
External egg morphology of common stored-product pests from the families Anobiidae (Ptininae) and Dermestidae (Coleoptera)
External egg morphology of some common stored-product pests from the families Anobiidae (Ptininae: Ptinus, Niptus) and Dermestidae (Trogoderma, Reesa) based on optical and scanning electron microscope (SEM) micrographs are presented. Diagnostic characteristics are described. Differences in the eggs of these families, genera and some species were found with respect to shape, size and surface structures. Keywords: Egg morphology, SEM micrographs, Stored-product pest identificatio
Procellaria westlandica in the Beagle Channel
El primer registro para Procellaria weslandica en Argentina está documentado por video y fotografía en el Canal Beagle
The Flower-Like Hierarchical Architectures Assembled from Aniline Oligomers
The flower-like hierarchical architectures assembled from aniline oligomers by a template-free method
are reported. They are important because of their close relation to a conducting polymer, polyaniline. Their
formation process is ascribed to the self-assembly of oligoanilines under non-covalent interactions, such as
hydrogen bonding, hydrophobic forces, and π–π stacking. The model of directional growth is offered to explain the formation of petal-like objects and, subsequently, flowers. In order to investigate the chemical
structure of the oligomers, a series of characterizations have been carried out, such as UV–visible, Fourier-transform infrared and Raman spectroscopies. Based on the results of characterization methods, a formation mechanism of the aniline oligomers and their self-assembly are proposed.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3484
The Formation of Oligoaniline Microspheres in Alkaline Media
Aniline oligomers are generally believed to be responsible for the self-assembly that guides the growth
of polyaniline nanostructures. The oxidations of aniline with ammonium peroxydisulfate, which are started
and finished above pH 2.5, produce aniline oligomers only. Under alkaline conditions, oligoaniline microspheres spheres are formed as the dominating morphology. They will be potentially useful in applications that do
not require conductivity, such as in electrorheology, corrosion protection, as ionic conductors or catalyst
supports. Aniline oligomers prepared at alkaline conditions as microspheres have been studied by UV–Vis,
infrared and Raman spectroscopies in the combination with optical and electron microscopic techniques.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3483
Integrated force interaction simulation model for milling strategy optimization of thin-walled Blisk blade machining
Complex shaped thin-walled blades that are extensively used in jet engines or stream turbines are very difficult to machine due to low rigidity of the blades, typically limited space between the blades and strict requirements on the surface quality and accuracy. The paper focuses on multi-axis machining of thin-walled and complex shaped Blisk blades made of aluminium alloys. The resulting surface quality and accuracy is mainly affected by the risk of elevated vibration occurrence, both forced and self-excited, and static deflections between the compliant tool and workpiece. An innovative integration of the transformed FE model of the blade into virtual machining simulation has been proposed, allowing to effectively solve the complex optimization task considering both the criterion of stable machining condition and static deflections as well. When choosing a machining strategy and cutting conditions, there are many variables that fundamentally affect the process. These variables are not easy to choose correctly the first time, so it is advisable to choose to use a simulation model in production preparation. The proposed simulation model allowed to effectively optimize the process parameters to keep the machining process stable and the static deformation of tool and workpiece under a defined level. The proposed model and optimization strategy was validated on a thin-walled blade machining. At the top part of the blade, the surface roughness decreased from 1.6 Ra to 0.84 Ra, and the maximum deviations from the reference model were reduced from 0.18 mm to 0.08 mm
Investigating substitutions in antibody–antigen complexes using molecular dynamics: a case study with broad-spectrum, Influenza A antibodies
In studying the binding of host antibodies to the surface antigens of pathogens, the structural and functional characterization of antibody–antigen complexes by X-ray crystallography and binding assay is important. However, the characterization requires experiments that are typically time consuming and expensive: thus, many antibody–antigen complexes are under-characterized. For vaccine development and disease surveillance, it is often vital to assess the impact of amino acid substitutions on antibody binding. For example, are there antibody substitutions capable of improving binding without a loss of breadth, or antigen substitutions that lead to antigenic escape? The questions cannot be answered reliably from sequence variation alone, exhaustive substitution assays are usually impractical, and alanine scans provide at best an incomplete identification of the critical residue–residue interactions. Here, we show that, given an initial structure of an antibody bound to an antigen, molecular dynamics simulations using the energy method molecular mechanics with Generalized Born surface area (MM/GBSA) can model the impact of single amino acid substitutions on antibody–antigen binding energy. We apply the technique to three broad-spectrum antibodies to influenza A hemagglutinin and examine both previously characterized and novel variant strains observed in the human population that may give rise to antigenic escape. We find that in some cases the impact of a substitution is local, while in others it causes a reorientation of the antibody with wide-ranging impact on residue–residue interactions: this explains, in part, why the change in chemical properties of a residue can be, on its own, a poor predictor of overall change in binding energy. Our estimates are in good agreement with experimental results—indeed, they approximate the degree of agreement between different experimental techniques. Simulations were performed on commodity computer hardware; hence, this approach has the potential to be widely adopted by those undertaking infectious disease research. Novel aspects of this research include the application of MM/GBSA to investigate binding between broadly binding antibodies and a viral glycoprotein; the development of an approach for visualizing substrate–ligand interactions; and the use of experimental assay data to rescale our predictions, allowing us to make inferences about absolute, as well as relative, changes in binding energy
Effect of Dilution on Microstructure and Wear Resistance of a Fe-Based Hardfacing Alloy with a High Amount of Carbide-Forming Elements
Hardfacing is a widely diffused technique adopted to increase service life of parts for heavy-duty applications. Even though
hardfacing alloys feature optimized chemistry and microstructure for specific service conditions, dilution with substrate modifies
the resulting properties along a significant fraction of the deposit thickness. In particular, C and B diffusion to the substrate alters
hypereutectic alloys reducing the carbide-forming ability andmodifying the solidification sequence. In the present paper, the effect
of dilution on a hypereutectic Fe-C-B based alloy containing Cr and Mo was investigated. The effect of dilution on the reference
alloy was studied by producing laboratory castings with an increased amount of Fe, up to 50 mass %. The obtained results were
compared with the dilution of the hardfacing alloy cast on steel substrates. The microstructural evolution was analyzed by XRD
(X-ray diffraction), differential scanning calorimetry (DSC), optical microscopy (OM), and scanning electron microscopy (SEM),
whereas mechanical behaviour was evaluated by hardness measurements and wear resistance by pin-on-disc tests
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