Characterization Of Fluids And Gases
Sujoy K. Guba in Bioengineering in Reproductive Medicine, 2020
Adaptation of an optical fiber as a chemical sensor requires the application of a layer of specific chemicals at the end of the fiber which change their fluorescent characteristics upon interaction with the chemical entity to be evaluated. A sensor for pH working on this principle was proposed by Peterson et al.4 These investigators used the dye phenol red (phenolsulfon-phthalein) as the light sensitive chemical. In the pH range 7.0 to 7.4 this dye acts as a weak acid of pK = 7.9 and exists in two tautomeric forms. Optical light absorption spectrum of these forms differ and the net spectra depends upon the relative proportion of the two forms. With change in pH the proportion changes and so the optical absorption of the dye in one of the peak absorption wavelengths can be used to measure the pH. The wavelength corresponding to the peak absorption of the base form is chosen for excitation because its optical density is greater than that of the acid form thereby giving higher sensitivity to pH change. A transducer probe is made by inserting a pair of optical fibers of about 0.15 mm diameter into a permeable cellulose tube (Figure 7.2) with phenol red dye coated Polyacrylamide microspheres filled into one end of the tube. Incoming light is transmitted by one fiber and the outgoing light is conducted by the other fiber. Intensity of the outgoing light is measured with a photocell and the intensity is a measure of the pH because hydrogen ions from the surrounding media diffuse across the cellulose tube wall and interact with the phenol red to change the relative tautomeric state and thereby the optical properties.
Synthesis, Enzyme Localization, and Regulation of Neurosteroids
Sheryl S. Smith in Neurosteroid Effects in the Central Nervous System, 2003
The holeboard apparatus provides independent measures of motor activity and exploration in rodents17,18,31,49 and comprises a square Plexiglas or wooden box measuring 60 × 60 cm for rats or 40 × 40 cm or 26 × 26 cm for mice. Holes are spaced equally in the floor and vary in number from 4 to 16 and in diameter from 2.2 to 6.5 cm. Photocells below the surface of the holes provide measures of the number of headdips and time spent head-dipping, while photocells within the sides of the box provide measures of locomotor activity and rearing. Typically, behavior within the holeboard apparatus is measured for 5 min. While anxiolytic drug effects on holeboard behavior (i.e., head-dips) did not correspond with measures of anxiety on the elevated plus maze (percent open-arm entries), exploration and locomotor activity in the holeboard were correlated with overall activity in the maze.17,18,42 Factor analysis for behavioral variables from the elevated plus maze and the holeboard found that the two indices of anxiety (i.e., percent open-arm entries and time) were highly correlated with each other and loaded on one factor, whereas the two measures of directed exploration (i.e., number of head-dips and duration of head-dipping) loaded on a separate factor.18,31 Nonetheless, anxiolytic drugs can affect holeboard behavior.17,18,42 Recent work in mice demonstrated that restraint stress and anxiolytic drugs produce opposite effects on head-dipping that are independent of locomotor activity50 and that strain differences in exploratory behavior differed from those found for locomotor activity.51
General Principles for Measuring Arterial Waves
Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos in McDonald's Blood Flow in Arteries, 2022
A photoelectric device for contact-free recording of phasic diameter waveforms of exposed arteries in situ was developed by Wetterer et al. (1977b). The device has been used to study the dynamic elastic properties of various arteries in both dogs and humans. The light emitted by a 6 W light bulb is collimated by a projection lens and directed onto the surface of a silicon photocell. The voltage drop caused by the photocell current flowing through an adjustable load resistor represents the signal voltage. This voltage decreases linearly with the increasing area of the shadow cast by the artery on the photocell and is thus proportional to the diameter of the artery.
Design of artificial cells: artificial biochemical systems, their thermodynamics and kinetics properties
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Adamu Yunusa Ugya, Lin Pohan, Qifeng Wang, Kamel Meguellati
Therefore, the minimal representations of synthetic cellularity using biological processes generated by bottom-up strategies are generating a growing interest in the field of synthetic biology. The use and development of in vitro gene expression systems (IVGES) is considered an advance in photocell engineering to provide off-line biological content for storage and processing in synthetic cell-free environments. Tang group used carboxymethyl-dextran/polylysine (CM-dextran/PLys) coacervate for the sequestration and retention of a plasmid-containing IVGES to show cell-free gene expression and folding of the red fluorescent protein mCherry at pH = 8 [30]. Another study on engineered cells in mammalian tissues is linked to a synthetic module (photoactivated synthesis of cyclic dimeric GMP) to obtain a 40-fold photoactivation of gene expression [36] (Figure 3). Recently, it was found that the oxygenation of stem cells is stimulated by artificial membrane-binding proteins during the engineering of large cartilage tissues [37]. It was reported in 1997 that the vesicle growth was driven by the simple dipeptide catalyst seryl-histidine (Ser-His) through the catalytic synthesis of a hydrophobic dipeptide, N-acteyl-L-phenylalanine-leucinamide (AcPheLeuNH2) [38].
Neuro-protective potential of quercetin during chlorpyrifos induced neurotoxicity in rats
Published in Drug and Chemical Toxicology, 2019
Simranjeet Kaur, Neha Singla, D. K. Dhawan
A computerized actophotometer (INCORP, INDIA) was used to measure the total locomotor activity (ambulation and rearing). Actophotometer is a square arena apparatus, which operates on photoelectric cells and are connected in circuit with a counter. An array of 16 infrared emitter/detector pairs measured the animal activity along a single axis of motion. The rats were allowed to acclimatize to the observation chamber for a period of 2 min. When the beam of light falling on the photocell was cut off by the animal, a count was recorded and finally, the activity was monitored for a total duration of 3 min (Singla and Dhawan 2017). The total locomotor activity was expressed as the mean of sum of total ambulatory photo beam counts and total rearing photo beam counts for 3 min per animal.
Daily rhythms of swimming activity, synchronization to different feeding times and effects on anesthesia practice in an Amazon fish species (Colossoma macropomum)
Published in Chronobiology International, 2018
Rodrigo Fortes-Silva, Silvan Vianna Do Valle, Jose Fernando Lopéz-Olmeda
Temporal restrictions of feeding can phase-shift behavioral and physiological circadian rhythms in fish. In this phase, we evaluated the effects of two different mealtimes on the daily swimming patterns of tambaqui and the occurrence of FAA. Forty-eight fish (body weight: 16.01 ± 0.18 g) were used and were randomly distributed into two groups. Each group was fed once a day every day at the same time: ML (fish fed in the mid-light phase, 12:00 h) and MD (fish fed in the mid-dark phase, 00:00 h). Each group contained six tanks with eight fish per tank. The feeding activity of all the groups was recorded for 20 days. To this end, an infrared photocell was placed inside each aquarium to face the automatic feeder in order to record FAA. As phase 1, all the photocells were connected to a computer, where data were stored for further analyses. As FAA has a gradual development, requiring several feeding cycles to appear (López-Olmeda 2017), only the last 7 days of Phase 2 were used to evaluate FAA. The occurrence and duration of FAA was determined as the time which elapsed between the feeding time and increased anticipatory activity, which was defined as a 2.5-fold increase over baseline activity, and which was sustained for at least 30 min and not followed by any inflection for more than 1 h, as described elsewhere (Stephan 1997; Costa et al. 2016).
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