The Photographic Record of Alternate Current Curves

1891 ◽  
Vol 32 (827supp) ◽  
pp. 13219-13219
1896 ◽  
Vol 42 (1084supp) ◽  
pp. 17330-17331
Author(s):  
J. A. Fleming

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Leonardo Pinto ◽  
Guilherme Soares ◽  
André Próspero ◽  
Erick Stoppa ◽  
Gabriel Biasotti ◽  
...  

Abstract The identification of gastrointestinal (GI) motility disorders requires the evaluation of regional GI transit, and the development of alternative methodologies in animals has a significant impact on translational approaches. Therefore, the purpose of this study was to validate an easy and low-cost methodology (alternate current biosusceptometry – ACB) for the assessment of regional GI transit in rats through images. Rats were fed a test meal containing magnetic tracer and phenol red, and GI segments (stomach, proximal, medial and distal small intestine, and cecum) were collected to assess tracer’s retention at distinct times after ingestion (0, 60, 120, 240, and 360 min). Images were obtained by scanning the segments, and phenol red concentration was determined by the sample’s absorbance. The temporal retention profile, geometric center, gastric emptying, and cecum arrival were evaluated. The correlation coefficient between methods was 0.802, and the temporal retention of each segment was successfully assessed. GI parameters yielded comparable results between methods, and ACB images presented advantages as the possibility to visualize intrasegmental tracer distribution and the automated scan of the segments. The imaging approach provided a reliable assessment of several parameters simultaneously and may serve as an accurate and sensitive approach for regional GI research in rats.


The lack of precision of measurements with alternate currents, as compared with those using direct currents, is mainly due to the relative sensitiveness of the instruments available for such tests. The fact that the turning moment acting on the moving system depends in one case on the square of the current and in the other on the first power of the current, readily explains the high ratio between the currents needed to cause the minimum measurable deflection in the two cases, but this ratio is, nevertheless, most striking when a numerical comparison is actually made on some fair basis. The only likely way at present of improving alternate current instruments is to use iron cored electromagnets to increase the strength of the magnetic field. I have found that the difficulties due to varying permeability and hysteresis of the iron can be avoided by exciting the electromagnet in shunt. It proves possible, with careful design, to construct an electromagnet whose flux is connected with the exciting voltage by a strict mathematical law involving no variable physical properties like permeability, etc. Such an electromagnet is eminently suited for measuring purposes. The theoretical and experimental study of instruments constructed on this principle has brought out certain novel points which are set forth in the present paper. The first part discusses the mathematical relations of cyclic quantities having a common fundamental period, and constitutes a development of a method already published. This method is the only one known to me which is independent of assumptions in regard to the wave form of the quantities dealt with. The usual methods, which are based on the erroneous assumptions of sine law wave form, are not any simpler in working, and are most unsatisfactory when the accuracy of new results has to be critically examined. All alternate current measurements refer to mean squares or to mean products, and the natural method of obtaining the connections between such squares and products is to study the properties of quadratic functions of the variables. The earliest instance of this in alternate current theory was in connection with the “three voltmeter method.” Such processes lead to a very simple form of calculus appropriate to cyclic quantities.


2017 ◽  
Vol 10 (1) ◽  
Author(s):  
N. Othman ◽  
A. Ahmad ◽  
M. A. Piramali

Demulsification is one of the key processes in emulsion liquid membrane application. This study involved the effect of electrical field on demulsification of water in oil using batch high voltage demulsifier system. This technique widely used because of its advantages of easy manipulation of applied field direction and strength, offers cost–effective separation and minimal environmental impact combined with mechanical simplicity. Influence of various values of frequency (400–1500 Hz) and voltage was studied experimentally using Alternate Current (AC) High Voltage Demulsifier with insulated electrode. The emulsion consists of kerosene as organic phase, sulfuric acid as internal phase and span 80 (3 and 5 w/v %) as a surfactant. The effect of emulsion preparation such as homogenizer speed, internal phase and surfactant concentrations on the stability of water–in–oil emulsion was also investigated. The results showed that the attractive forces between the water droplets under an electrical field increase by raising the applied electrical field strength. Meanwhile, the time required for the emulsion to separate and coalescence under electrical field increased when the stability of emulsion increased.


2020 ◽  
Vol 46 (4) ◽  
pp. 735-738
Author(s):  
Rajib Dey ◽  
Sourabh Biswas

Prosotas pia is reported from Jayanti riverbed (26.747066 N, 89.636343 E). Therefore, this note reports a new finding of this butterfly, being incorporated to the existing West Bengal lepidoptera list with a photographic record from the Buxa Tiger Reserve, West Bengal, India.


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