Ultrasonic probes cells

Figure 4.6. Coupling of continuous ultrasound-assisted leaching and detection in an open (A) and a closed manifold with the detection system in the circuit for monitoring the leaching process (B). C — coil, D — debubbler, DS — detection system, FC — flow cell, L- leachant, LC — leaching chamber, PC — personal computer, PL — propagating liquid, PP — peristaltic pump, SV— switching valve, UP— ultrasonic probe, 1/1/— waste and WB — water bath.

Figure 8.15. Thermostated electrochemical cells employed for sonovoltammetry. (A) With an ultrasonic bath. (B) With an ultrasonic probe (Reproduced with permission of Elsevier, Refs. [133,154], respectively.)...

Can we probe cell mechanics with ultrasonics via non-invasive and innocuous techniques ... 

Second, a cell of larger dimensions (200-500 mL) is shown in Fig. 1(h) in which both the counterelectrode compartment and a thermostating coil surround the ultrasonic horn. The working electrode, typically a gauze or cloth of suitable material [7], is placed directly underneath the ultrasonic probe. 

A mixture of m-chloroperbenzoic acid (MCPBA, 55% purity in 10% m-chlorobenzoic acid and 35% water, from Merck, 0.32 g), methyl oleate (Aldrich, 0.2 g, 0.68 mmol) and deionized water (25 mL) was placed in a water-cooled glass cell. Sonication was carried out using a 20-kHz (53W cm"2) ultrasound horn (Sonoreactor, Undatim Ultrasonics, Louvain la Neuve, Belgium), in a water-cooled jacketed glass cell (40 mm i.d., 80 mm length). The tip of the ultrasonic probe was submersed to 5 mm below the surface of the reaction mixture and the system was sonicated for 15 min with the temperature maintained at about 20°C by water circulating through the jacket. 

Two major sources of ultrasound are employed, namely ultrasonic baths and ultrasonic immersion hom probes [79, 71]- The fonuer consists of fixed-frequency transducers beneath the exterior of the bath unit filled with water in which the electrochemical cell is then fixed. Alternatively, the metal bath is coated and directly employed as electrochemical cell, but m both cases the results strongly depend on the position and design of the set-up. The ultrasonic horn transducer, on the other hand, is a transducer provided with an electrically conducting tip (often Ti6A14V), which is inuuersed in a three-electrode thenuostatted cell to a depth of 1-2 cm directly facing the electrode surface. 

Most chemists working on sonochemistry in the laboratory will either use some form of ultrasonic bath or a commercial probe system. The latter instruments are often equipped with a pulse facility which was originally designed for biological cell disruption where temperature control is important. This pulse facility enables the power ultrasound to be delivered intermittently and thereby allow periods of cool-... 

Ultrasonic waves, produced by a sonicator, are transmitted into a suspension of cells by a metal probe (Figure E4.1C). The vibration set up by the ultrasonic waves disrupts the cell membrane, releasing the cell components into the surrounding aqueous solution. 

An application of ultrasound that is becoming increasingly popular in the food industry is the determination of creaming and sedimentation profiles in emulsions and suspensions (Basaran et al., 1998). Acoustic techniques can also assess nondestructively the texture of aerated food products such as crackers and wafers. Air cells, which are critical to consumer appreciation of baked product quality, are readily probed due to their inherent compressibility (Elmehdi et al., 2003). Kulmyrzaev et al. (2000) developed an ultrasonic reflectance spectrometer to relate ultrasonic reflectance spectra to bubble characteristics of aerated foods. Experiments were carried out using foams with different bubble concentration and the results showed that ultrasonic reflectance spectrometry is sensitive to changes in bubble size and concentration of aerated foods. 

Sonication This involves the generation of shear forces in a cell sample in the vicinity of a titanium probe (0.5 mm in diameter and 10 cm long) that vibrates at 20,000 Hz. The device contains a crystal of lead zirconate titanate that is piezoelectric, i.e., it expands and contracts when an oscillatory electric field is applied to it from an electronic oscillator. The ultrasonic pressure waves cause microcavitation in the sample, and this disrupts the cell membranes, usually in a few seconds. 

The variables concerned with the relative position of the probe and sample eell and their surroundings are the depth of the probe in the transmitting liquid, the probe-sample cell distance, the size and shape of the reservoir holding the liquid transmitter and the nature of the liquid. The depth of the probe in the liquid also containing the sample cell is considered because if the probe is only slightly immersed, it causes foaming at the liquid surface, which in turn results in the loss of ultrasonic energy on the other hand. 

Feed slurry is introduced into the basket through either single or multiple feed pipes, or by other means such as rotating feed cone to help distribute the solids on the basket wall. In most cases, feed slurry is introduced at an intermediate speed, although in some applications (FGD gypsum, for one), feeding is done at full speed. There are several methods available to control the feed and cake level such as mechanical, paddle-type feelers, capacitance probes, ultrasonic sensors, feed totalizer, or load cells. 

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