Structural study of the salivary glands of Anocentor nitens (Acari: Ixodidae) during the feeding cycle

The salivary glands of Anocentor nitens (Neumann, 1897 ) occur in pairs and are located in the anterolateral region of the general cavity, with milky white color and approximately equal sizes. They consist of a secretory portion and an excretion duct. In some glandular acini, all the cells had a basophilic appearance they were stained by hematoxylin, whereas others presented cells with different staining affinities. In this work, we describe the variations observed in these glands during the feeding cycle of ticks [after feeding (0 h) and successively at 24, 48, 72, 96, 120, and 144 h]. The cells stained by hematoxylin were shown to be more reactive to Alcian blue, thus demonstrating the presence of acid glycosaminoglycans, whereas those stained using eosin presented weak or no reaction. A strong reaction was found by the use of the periodic acid‐Schiff (PAS) technique, thereby suggesting the presence of glycogen and/or glycoconjugates containing hexose, confirmed by using salivary amylase before PAS, with partial destaining of the slides. Continuing presence of residual staining in these cells suggests the presence of glycoconjugates containing hexose. Cells with nuclei of circular outline and few granules (of different sizes) were found in type II acini, 72 h after collection. Type I acini presented wide lumina and walls composed of larger numbers of cells of cubic to cylindrical shape. The pronounced degranulation shown in this study over the course of the feeding cycle was associated with the release of substances for oviposition. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.     

Model-based engineering in the embedded systems domain: an industrial survey on the state-of-practice

Model-based engineering (MBE) aims at increasing the effectiveness of engineering by using models as important artifacts in the development process. While empirical studies on the use and the effects of MBE in industry exist, only few of them target the embedded systems domain. We contribute to the body of knowledge with an empirical study on the use and the assessment of MBE in that particular domain. The goal of this study is to assess the current state-of-practice and the challenges the embedded systems domain is facing due to shortcomings with MBE. We collected quantitative data from 113 subjects, mostly professionals working with MBE, using an online survey. The collected data spans different aspects of MBE, such as the used modeling languages, tools, notations, effects of MBE introduction, or shortcomings of MBE. Our main findings are that MBE is used by a majority of all participants in the embedded systems domain, mainly for simulation, code generation, and documentation. Reported positive effects of MBE are higher quality and improved reusability. Main shortcomings are interoperability difficulties between MBE tools, high training effort for developers and usability issues. Our study offers valuable insights into the current industrial practice and can guide future research in the fields of systems modeling and embedded systems.     

Modelling, simulation and control of an industrial, semi-batch, emulsion-polymerization reactor

This paper presents an emulsion-polymerization model that is designed for an industrial, semi-batch reactor. The model consists of a reaction model and a calorimetry model, and as such enables us to predict the reactor temperature and the batch-output parameters, i.e., the conversion, the solids content and the viscosity. The model was validated on real-plant data and used in the analysis and design of the reactants dosing control. The control strategy proposed is valid for cases where evaporative cooling is either the only or an additional way to remove the heat of the reaction. It consists of an initiator and monomer dosing control, using the reactor temperature as a controlled variable. The simulation results and the real-plant testing show that the proposed reactants dosing control significantly reduces the variations in the reactor temperature and at the same time results in more uniform batch results.     

Impact of powder morphology on quality of low-pressure injection moulded reaction-bonded net shape oxide ceramics

Low-pressure injection moulding is a very efficient process for net shape manufacturing of ceramic micro parts. In order to obtain sintered ceramic specimens without shape distortion or damages, density gradients in the green bodies have to be avoided. Especially feedstocks with a solid loading near the critical powder volume content often tend to segregate the binder while flowing. However, the value of critical powder content can be significantly influenced by particle size, particle size distribution and particle morphology. This paper compares two powder mixtures of identical chemical compositions with different specific surfaces and morphology and evaluates their workability for low-pressure injection moulding. The aim of this paper is to identify the influence of morphology on feedstock rheology as well as on accuracy, mechanical properties and microstructure of net shape manufactured reaction-bonded zircon ceramics.     

Inventory centralization decision framework for spare parts

Within the current literature, there is a lack of a holistic and multidisciplinary approach to managing spare parts and their inventory configuration. This paper addresses this research gap by examining the key contextual factors which influence the degree of inventory centralization and proposes a novel holistic theoretical framework, the Inventory Centralization Decision Framework (ICDF), useful for practitioners. Through an extensive review of inventory management literature, six contextual factors influencing the degree of inventory centralization have been identified. Using the ICDF practitioners can assess the most advantageous inventory configuration of spare parts. The framework is tested on a large global company which, as a result, today actively uses the ICDF; thus showing its practical applicability.     

Transition in occupational radiation exposure monitoring methods in diagnostic and interventional radiology

Radiation exposure monitoring is a traditional keystone of occupational radiation safety measures in medical imaging. The aim of this study was to review the data on occupational exposures in a large central university hospital radiology organisation and propose changes in the radiation worker categories and methods of exposure monitoring. An additional objective was to evaluate the development of electronic personal dosimeters and their potential in the digitised radiology environment. The personal equivalent dose of 267 radiation workers (116 radiologists and 151 radiographers) was monitored using personal dosimeters during the years 2006-2010. Accumulated exposure monitoring results exceeding the registration threshold were observed in the personal dosimeters of 73 workers (59 radiologists' doses ranged from 0.1 to 45.1 mSv; 14 radiographers' doses ranged from 0.1 to 1.3 mSv). The accumulated personal equivalent doses are generally very small, only a few angiography radiologists have doses >10 mSv per 5 y. The typical effective doses are <10 μSv y(-1) and the highest value was 0.3 mSv (single interventional radiologist). A revised categorisation of radiation workers based on the working profile of the radiologist and observed accumulated doses is justified. Occupational monitoring can be implemented mostly with group dosimeters. An active real-time dosimetry system is warranted to support radiation protection strategy where optimisation aspects, including improving working methods, are essential.     

Morphological Control Over Gel Structures of Mixed Semiconductor-Metal Nanoparticle Gel Networks with Multivalent Cations

In this work, the influence of two different types of cations on the gel formation and structure of mixed gel networks comprised of semiconductor (namely CdSe/CdS nanorods NR) and Au nanoparticles (NP) as well as on the respective monocomponent gels is investigated. Heteroassemblies built from colloidal building blocks are usually prepared by ligand removal or cross-linking, thus, both the surface chemistry and the destabilising agent play an essential role in the gelation process. Due to the diversity of the composition, morphology, and optical properties of the nanoparticles, a versatile route to fabricate functional heteroassemblies is of great demand. In the present work, the optics, morphology, and gelation mechanism of pure semiconductor and noble metal as well as their mixed nanoparticle gel networks are revealed. The influence of the gelation agents (bivalent and trivalent cations) on the structure-property correlation is elucidated by photoluminescence, X-ray photoelectron spectroscopy, and electron microscopy measurements. The selection of cations drastically influences the nano- and microstructure of the prepared gel network structures driven by the affinity of the cations to the ligands and the nanoparticle surface. This gelation technique provides a new platform to control the formation of porous assemblies based on semiconductor and metal nanoparticles.     

Low frequency dielectric spectroscopy of bitumen binders as an indicator of adhesion potential to quartz aggregates using Portland cement

The purpose of this investigation was to interpret the bitumen-aggregate adhesion based on the dielectric spectroscopic response of individual material components utilizing their dielectric constants, refractive indices and average tangent of the dielectric loss angle (average loss tangent). Dielectric spectroscopy of bitumen binders at room temperature was performed in the frequency range of 0.01–1000 Hz. Dielectric spectroscopy is an experimental method for characterizing the dielectric permittivity of a material as a function of frequency. Adhesion data has been determined using the Rolling bottle method. The results show that the magnitude of the average tangent of the dielectric loss angle (average loss tangent) depends on bitumen type. The average loss tangent in the frequency range 0.01–1 Hz is introduced as a potential indicator for predicting polarizability and, thereby, adhesion potential of bitumen binders to quartz aggregates when using Portland cement. In order to obtain acceptable adhesion of 70/100 penetration grade bitumen binders and quartz aggregates when using Portland cement, it is suggested that the binder have an average tan δ > 0.035 in the frequency range 0.01–1 Hz.     

Chloride Ion Mediated Synthesis of Metal/Semiconductor Hybrid Nanocrystals

A synthetic route to prepare metal–semiconductor hybrid nanoparticles is presented, along with the possibility to tune the ratio of primary to secondary nucleation and the morphology of the semiconductor material grown on the metal nanoparticle seeds. Gold and cobalt‐platinum nanoparticles are employed as metal seeds, on which CdS or CdSe is grown. Using transmission electron microscopy, absorption spectroscopy (UV–vis), and powder X‐ray diffraction as characterization techniques, a significant influence of chloride ions on the type of nucleation (that is, secondary or primary nucleation) as well as on the shape of the resulting heterostructures is observed. Partially replacing the commonly used cadmium precursor CdO by varying amounts of CdCl₂ opens access to rod‐like, multiarmed, flower‐like, and bullet‐like structures. The results suggest that neither pure CdO nor pure CdCl₂ as precursors but only a mixture of both make these structures obtainable. In this article, the influence of the chloride ion concentration during semiconductor growth on metal seeds is investigated in depth. The morphology of the resulting heterostructures is characterized carefully, and a growth mechanism is suggested. Furthermore, it is shown that this synthetic approach can be transferred to seeds of various metals such as platinum, gold, and cobalt platinum.