Investigation of complex permittivity spectra of foundry sands

2020 ◽  
Vol 87 (5) ◽  
pp. 372-380
Author(s):  
Luca Bifano ◽  
Alice Fischerauer ◽  
Gerhard Fischerauer
Keyword(s):  
Quartz Sand ◽  
Control Strategies ◽  
Equivalent Circuit Model ◽  
Impedance Spectrum ◽  
Nyquist Plot ◽  
Impedance Spectra ◽  
Foundry Sands ◽  
Different Types ◽  
Regeneration Processes

AbstractThis paper discusses impedance spectroscopy as a method to characterize different types of quartz sand, chromite sand, and mixtures of sand. Based on two types of measurement cells, the impedance spectra for various dry sands were measured. The spectra differ enough to allow the sands to be distinguished. The results were validated by extracting the relative permittivity from the impedance and comparing it to literature data. After that, the method could be applied with confidence to other material systems. The influence of moisture was investigated with two types of quartz sand, and typical mixtures of form sand, chromite sand, and regenerated (quartz) sand were studied. In each case, the sand composition had a distinct influence on the Nyquist plot of the impedance spectrum. Compared to results from a laboratory foundry system, the new method exhibits a much more systematic dependence on the sand composition. If one succeeds in describing the impedance spectra with an equivalent circuit model parameterized by only a few parameters, these parameters could be used to identify and classify sand mixtures in the field. This would allow one, for example, to implement feedback control strategies in foundry regeneration processes, which would stabilize the processes and improve the quality of the casting products.

Influence of Leaning Materials on the Quality of Building Ceramics

2021 ◽  
Vol 903 ◽  
pp. 197-202
Author(s):  
Ruta Švinka ◽  
Visvaldis Švinka ◽  
Maris Rundans ◽  
Inta Timma ◽  
Laila Petersone
Keyword(s):  
Thermal Expansion ◽  
Glass Fibre ◽  
Material Properties ◽  
Quartz Sand ◽  
Main Method ◽  
Different Types ◽  
Ceramic Building ◽  
Formation Of Cracks

Clay of the deposit Liepa is used for the production of ceramic building and finishing bricks in the factory “Lode” in Latvia. In the present work different types of these clays were investigated and “quartz effect” was determined using quartz sand as a leaning material. The substitution of quartz sand with milled E-glass fibre from Valmiera Glass was investigated and the changes in the magnitude of the quartz inversion effect were analysed. Thermal expansion was the main method for the determination of possible formation of cracks during technological process. Powder of milled glass fibre in amount of 5–10 % affects such properties as water uptake, porosity and apparent density and provides the required material properties at a lower firing temperature.

scholarly journals Effects of Lead Exposure on Blood Electrical Impedance Spectroscopy of Mice

2021 ◽  
Author(s):  
Binying Yang ◽  
Jia Xu ◽  
Shao Hu ◽  
Boning You ◽  
Qing Ma
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Lead Exposure ◽  
Electrical Impedance ◽  
Equivalent Circuit Model ◽  
Impedance Spectrum ◽  
Nyquist Plot ◽  
Electrical Impedance Spectroscopy ◽  
Impedance Method ◽  
Range Data

Abstract Background: Lead is a nonessential heavy metal, which can inhibit heme synthesis and has significant cytotoxic effects. Nevertheless, its effect on the electrical properties of red blood cells (RBCs) remains unclear. Consequently, this study aimed to investigate the electrical properties and the electrophysiological mechanism of lead exposure in mouse blood using Electrical Impedance Spectroscopy (EIS). Methods: AC impedance method was used to measure the electrical impedance of healthy and lead exposure blood of mice in 0.01-100 MHz frequency range. Data characteristic of the impedance spectrum, Bodes plot, Nyquist plot and Nichols plot, and three elements equivalent circuit model were used to explicitly analyze the differences in amplitude-frequency, phase-frequency, and the frequency characteristic of blood in electrical impedance properties. Results: Compared with the healthy blood in control mice, the changes in blood exposed to lead was as follows: (I) the hematocrit decreased; (II) the amplitude-frequency and phase-frequency characteristics of electrical impedance decreased; (III) the characteristic frequencies ( f 0 ) were significantly increased; (IV) the electrical impedance of plasma, erythrocyte membrane, and hemoglobin decreased, while the conductivity increased. Conclusion: Therefore, EIS can be used as an effective method to monitor blood and RBCs abnormalities caused by lead-exposure.

scholarly journals Examination of Behavior from Selected Foundry Sands with Alkali Silicate-Based Inorganic Binders

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 235
Author(s):  
Iveta Vasková ◽  
László Varga ◽  
Ingo Prass ◽  
Viktoria Dargai ◽  
Martin Conev ◽  
...  
Keyword(s):  
Automotive Industry ◽  
Combustion Engines ◽  
Foundry Sands ◽  
Casting Technology ◽  
Sand Core ◽  
Coarse Grains ◽  
Different Types ◽  
Engine Blocks ◽  
New Generation

The automotive industry is one of the most important customers for the foundry industry. In particular, casting of engine parts for combustion engines is one of the most demanding areas of casting technology. New generation of engine blocks and cylinder heads are getting geometrically more complicated in order to maintain or even increase performance. With the increased complexity, the strain for the casting molds is growing and the widely used technology of core making with standard silica sands is, for several applications, no longer reaching the demanded results. Furthermore, in last decade, there has been an effort in using inorganic binders in core making process, which brings along some additional technological challenges. In order to cope with these challenges, in this paper, silica and non-silica sands with round and angular grains as well as with fine and coarse grains are examined using an inorganic binder for strength, permeability, and thermal stability. The results shall provide useful information about the possibilities of application and combining different types of foundry sands, both silica and non-silica. With their impact on the selected sand core properties, they can help in solving problems in the core making process as well as reaching a high quality of the final product-casting.

scholarly journals Effects of lead exposure on blood electrical impedance spectroscopy of mice

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Binying Yang ◽  
Jia Xu ◽  
Shao Hu ◽  
Boning You ◽  
Qing Ma
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Lead Exposure ◽  
Electrical Impedance ◽  
Equivalent Circuit Model ◽  
Impedance Spectrum ◽  
Nyquist Plot ◽  
Frequency Characteristics ◽  
Electrical Impedance Spectroscopy ◽  
Range Data

Abstract Background Lead is a nonessential heavy metal, which can inhibit heme synthesis and has significant cytotoxic effects. Nevertheless, its effect on the electrical properties of red blood cells (RBCs) remains unclear. Consequently, this study aimed to investigate the electrical properties and the electrophysiological mechanism of lead exposure in mouse blood using Electrical Impedance Spectroscopy (EIS) in 0.01–100 MHz frequency range. Data characteristic of the impedance spectrum, Bodes plot, Nyquist plot and Nichols plot, and Constant Phase Element (CPE) equivalent circuit model were used to explicitly analyze the differences in amplitude–frequency, phase–frequency, and the frequency characteristics of blood in electrical impedance properties. Results Compared with the healthy blood in control mice, the changes in blood exposed to lead were as follows: (i) the hematocrit decreased; (ii) the amplitude–frequency and phase–frequency characteristics of electrical impedance decreased; (iii) the characteristic frequencies (f0) were significantly increased; (iv) the electrical impedance of plasma, erythrocyte membrane, and hemoglobin decreased, while the conductivity increased. (v) The pseudo-capacitance of cell membrane (CPE_Tm) and the intracellular pseudo-capacitance (CPE-Ti) were decreased. Conclusions Therefore, EIS can be used as an effective method to monitor blood and RBC abnormalities caused by lead exposure. The electrical properties of the cells can be applied as an important observation in the evaluation of the toxic effects of heavy metals.

Enumeration of Cryptosporidium oocysts from surface water concentrates by laser-scanning cytometry

2000 ◽  
Vol 41 (7) ◽  
pp. 197-202 ◽  
Author(s):  
F. Zanelli ◽  
B. Compagnon ◽  
J. C. Joret ◽  
M. R. de Roubin
Keyword(s):  
Surface Water ◽  
Water Samples ◽  
Laser Scanning ◽  
Immunomagnetic Separation ◽  
Entire Surface ◽  
Cryptosporidium Oocysts ◽  
Different Types ◽  
Laser Scanning Cytometry ◽  
Direct Microscopic Observation

The utilization of the ChemScan® RDI was tested for different types of water concentrates. Concentrates were prepared by cartridge filtration or flocculation, and analysed either without purification, or after Immunomagnetic separation (IMS) or flotation on percoll-sucrose gradients. Theenumeration of the oocysts was subsequently performed using the ChemScan® RDI Cryptosporidium application. Enumeration by direct microscopic observation of the entire surface of the membrane was carried out as a control, and recoveries were calculated as a ratio between the ChemScan® RDI result and the result obtained with direct microscopic enumeration. The Chemscan enumeration technique proved reliable, with recoveries yielding close to 100% in most cases (average 125%, range from 86 to 467%) for all the concentration/purification techniques tested. The quality of the antibodies was shown to be critical, with antibodies from some suppliers yielding recoveries a low as 10% in some cases. This difficulty could, however, be overcome by the utilization of the antibody provided by Chemunex. These data conclusively prove that laser scanning cytometry, which greatly facilitates the microscopic enumeration of Cryptosporidium oocysts from water samples and decreases the time of observation by four to six times, can be successfully applied to water concentrates prepared from a variety of concentration/purification techniques.

scholarly journals New Orthophoto Generation Strategies from UAV and Ground Remote Sensing Platforms for High-Throughput Phenotyping

2021 ◽  
Vol 13 (5) ◽  
pp. 860
Author(s):  
Yi-Chun Lin ◽  
Tian Zhou ◽  
Taojun Wang ◽  
Melba Crawford ◽  
Ayman Habib
Keyword(s):  
Remote Sensing ◽  
Control Strategies ◽  
Target Function ◽  
Canopy Cover ◽  
Surface Model ◽  
Flowering Date ◽  
Sensing Platforms ◽  
Geolocation Accuracy ◽  
New Strategies

Remote sensing platforms have become an effective data acquisition tool for digital agriculture. Imaging sensors onboard unmanned aerial vehicles (UAVs) and tractors are providing unprecedented high-geometric-resolution data for several crop phenotyping activities (e.g., canopy cover estimation, plant localization, and flowering date identification). Among potential products, orthophotos play an important role in agricultural management. Traditional orthophoto generation strategies suffer from several artifacts (e.g., double mapping, excessive pixilation, and seamline distortions). The above problems are more pronounced when dealing with mid- to late-season imagery, which is often used for establishing flowering date (e.g., tassel and panicle detection for maize and sorghum crops, respectively). In response to these challenges, this paper introduces new strategies for generating orthophotos that are conducive to the straightforward detection of tassels and panicles. The orthophoto generation strategies are valid for both frame and push-broom imaging systems. The target function of these strategies is striking a balance between the improved visual appearance of tassels/panicles and their geolocation accuracy. The new strategies are based on generating a smooth digital surface model (DSM) that maintains the geolocation quality along the plant rows while reducing double mapping and pixilation artifacts. Moreover, seamline control strategies are applied to avoid having seamline distortions at locations where the tassels and panicles are expected. The quality of generated orthophotos is evaluated through visual inspection as well as quantitative assessment of the degree of similarity between the generated orthophotos and original images. Several experimental results from both UAV and ground platforms show that the proposed strategies do improve the visual quality of derived orthophotos while maintaining the geolocation accuracy at tassel/panicle locations.

Different Types of Auricular Keloids and Treatment by Intralesional Cryosurgery: Best Practice for Obtaining Long-Lasting Clinical Results

Dermatology ◽  
2021 ◽  
pp. 1-10
Author(s):  
Yaron Har-Shai ◽  
Lior Har-Shai ◽  
Viktor A. Zouboulis ◽  
Christos C. Zouboulis
Keyword(s):  
Quality Of Life ◽  
Body Image ◽  
Recurrence Rate ◽  
Best Practice ◽  
Clinical Results ◽  
Psychosocial Impact ◽  
Aesthetic Outcome ◽  
The Past ◽  
Different Types

<b><i>Background:</i></b> Auricular keloids belong to the most perplexing medical conditions, which have significant psychosocial impact on the patient’s body image and quality of life. <b><i>Summary:</i></b> The article is purposed to provide dermatologists and plastic surgeons with the best proven practice using intralesional cryosurgery for the treatment of the different auricular keloid types in order to obtain superior clinical results by minimizing the probability of recurrence. In the past 20 years, the authors have developed novel procedures in order to increase the effectiveness of intralesional cryosurgery on auricular keloids, including hydrodissection, warm gauze technique, and excision of dangling skin. Long-lasting clinical results with a low recurrence rate and a satisfactory aesthetic outcome are achieved with no deformation of the ear framework.

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