Magnetic Fluids and Their Use in Transducers

Magnetic fluids are now widely used to implement transducer architectures. These fluids have valuable properties compared to traditional materials. In this column, a brief overview of magnetic fluids and their traditional uses in the field of transducers are given and some applications developed at the DIEES laboratory at the University of Catania, Italy are presented     

Tocopherol levels in the plasma lipoproteins from Japanese eel Anguilla japonica

The alpha- and gamma-tocopherol levels in the plasma of Japanese eel (Anguilla japonica) were 53.9 micrograms and 1.3 micrograms/ml of plasma, respectively. The alpha-tocopherol in the plasma was mainly distributed as very-low-density lipoprotein and low-density lipoprotein (LDL), while LDL and high-density lipoprotein constituted most of the gamma-tocopherol. A highly positive coefficient of correlation was observed between the alpha-tocopherol and lipoprotein contents in Japanese eel plasma.     

Design optimization of tall tubular lead/acid cells based on an analysis of the reaction distribution

In order to estimate the discharge performance of tall lead/acid cells (with tubular positives), changes in current and potential distributions with discharge progress were calculated with a computer on the basis of plate resistance and the current—potential—time relationship between small facing parts of positive and negative plates. The taller the cell, the larger the voltage drop along the plates. Thus, the discharge time became shorter despite a large amount of available active mass remaining in the bottom part of the plates.Various current-collector designs were evaluated, e.g., one with varying resistance at each height; a side conductor placed along the plates and connected to them at the top, centre and bottom, etc. Results revealed an optimum collector design with which the maximum discharge capacity could be obtained. Furthermore, it was shown that the side conductor markedly improved the discharge performance because the active mass near the connecting parts was appreciably used.     

An analysis of a waveguide T junction with an inductive post

The authors analyze the T junction with an inductive post, taking its diameter into account for the case where the current distribution is assumed on the surface of the post. A single cylindrical post placed in a T junction improves the impedance matching and compensates the junction discontinuity in a wide frequency band. The effects of the design parameters, such as the diameter of the post and its location, are clarified. The measured return loss is accurately predicted. On the basis of this analysis, an effective design procedure for the T junction is proposed, and the reflection below -30 dB is realized over 4% bandwidth     

A new direction or class assistance during laboratory sessions

Experimental training for undergraduate students in electric and electronic engineering courses must take advantage of emerging technologies. PC-based measurement systems, as well as, virtual instruments are very useful for beginners, which help test theoretical knowledge, carry out useful self-training, and acquire basic hands-on experience with problems arising in real-world experimental trials. Still, training with real instruments in a laboratory can provide students the necessary experience in measurement procedures and basic expertise in the design of measurement systems. Great efforts must be made in the development of new methodologies and tools able to fit the requirements of classes involved in experimental sessions. Advanced technologies can support the development of highly featured and capable laboratory sessions. As an example, the client-server tool presented in this article represents a partial result of a step-by-step ongoing work, which includes a suitable software interface and circuits that will be used to carry out classical experiments. The system has proved to be very useful for the experimental training of undergraduates and they can use it by themselves through a user-friendly interface. Moreover, the laboratory is available for greater lengths of time and can solve the problem of the lack of an adequate number of tutors.     

Use of external conduit impairs liver function in patients with biliary atresia

An external conduit (stoma) for patients with biliary atresia has been used to prevent postoperative cholangitis. Thirty-two patients with biliary atresia who had hepatic portoenterostomies with external conduits were studied retrospectively with respect to frequency and severity of postoperative cholangitis or stoma bleeding. Changes in their liver enzyme levels, and total bilirubin (TB) levels were measured before and after closure of the stoma. Cholangitis was observed in 20 patients (62.5%), and major hemorrhage from the stoma site was seen in 14 patients (43.8%) prior to closure. Levels of liver enzymes such as glutamic oxaloacetic transaminase (SGOT), glutamic pyruvic transaminase (SGPT), gamma-glutamyl transpeptidase (gamma-GTP), and alkaline phosphatase (ALP) improved significantly within 1 month after closure of the stoma, and remained low thereafter. The TB concentration was the only liver function that did not change significantly following closure. In summary, the authors do not recommend an external conduit in patients with biliary atresia because it is not an effective way of reducing the incidence of postoperative cholangitis, and it may be deleterious to liver function.     

Discharge behaviour of electrodeposited PbO2 and Pb electrodes

The discharge behaviour of electrodeposited lead dioxide and lead electrodes was investigated under various conditions; the surfaces of the discharged electrodes were observed with a scanning electron microscope. Both the positive and negative electrodes were passivated by a covering of deposited lead sulphate crystals. The amount of lead sulphate required for passivation depended on the size of the crystals.     

Elimination of fictitious penetrating rays from PO and hybridization with AFIM

Physical optics (PO) is an approximation method for high‐frequency scattering and diffraction problems. But PO fields are inaccurate in the shadow region where the source is screened by the scatter. Two key factors of the error for PO are (i) edge diffraction coefficients and (ii) existence of fictitious penetrating rays. The correction with respect to the former has been extensively investigated by many authors using various ray techniques such as GTD, UTD, and UAT. On the other hand, the latter was identified recently by the authors. This paper proposes novel PO‐based calculation procedures termed PO‐AF and PTD‐AF, where PO and Aperture Field Integration Method (AFIM) are merged with the help of special elementary diffraction coefficients. These can uniformly cover the whole angular region and only the error factor (ii) is removed in PO‐AF while both (i) and (ii) are removed in PTD‐AF. The theoretical backgrounds of PO currents are discussed in terms of field equivalence theorem and visualization of EM waves. Next, new methods are proposed and their validity is numerically demonstrated for 2D scattering problems of a strip, a corner reflector, and a cylinder of circular arc. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 1–10, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20037     

Esophageal stimulation by hydrochloric acid causes neurogenic inflammation in the airways in guinea pigs

To investigate whether tachykinins are released in the airways in response to stimulation of the esophagus, we studied the airway plasma extravasation induced by intraesophageal HCl in the presence or absence of neutral endopeptidase inhibitor phosphoramidon and NK1-receptor antagonist FK-888 in anesthetized guinea pigs. The airway plasma leakage was evaluated by measuring extravasated Evans blue dye in the animals pretreated with propranolol and atropine. Infusion of 1 N HCl into the esophagus significantly increased plasma extravasation in the trachea. Phosphoramidon significantly potentiated plasma extravasation in the trachea and main bronchi, whereas FK-888 significantly inhibited that extravasation in a dose-related manner. In the capsaicin-treated animals, airway plasma extravasation was completely inhibited even in the presence of phosphoramidon. Tracheal plasma extravasation potentiated by phosphoramidon was significantly inhibited in the bilateral vagotomized animals. These results suggest that 1) tachykinin-like substances are released to cause plasma extravasation in the airways as a result of intraesophageal HCl stimulation and 2) there are neural pathways communicating between the esophagus and airways, including the vagus nerve.