Tension records

Figure 1. Original records of tension and intracellular free calcium concentration Caf ) obtained from a single mouse muscle fiber during a fatigue run (modified from Westerblad and Allen, 1991). A continuous tension record in which each vertical line represents a tetanus. B (Ca ] (measured with fura-2) and tension records obtained from the individual tetani (a, b, and c) indicated above the record in A. Three major features are illustrated 1.) the initial tension decline is accompanied by an increase in tetanic ICa li, 2.) late in fatigue the tetanic [Ca li is reduced, and 3.) the resting [Ca li increases during fatiguing stimulation (dashed line indicates resting [Ca ] in control). Stimulation periods are shown below tension records in B. From Westerblad et al., 1991, with permission from the Amer. Physiol. Society.

The maximum surface tension recorded is proportional to the force needed to remove the ring from the liquid interface and is directly proportional to the surface tension of the liquid. Figure D3.6.2 shows a plot of the recorded force as a function of the experimental time. Modern tensiometers that are connected to a computer not only record the entire experiment but also automatically compute the surface tension. 

Fig. 9.6 Top intracellular sodium activity and tension recorded in a cardiac Purkinje fiber during rest and during a period of repetitive stimulation at 2 Hz [28]. Middle reconstruction using a model ventricular cell showing intracellular sodium and calcium...

Figure 5. Action potentials and developed tension recorded from canine papillary muscle before (A) and after 1 X 10 6 M (B) and 1 X 10 5 M (C) 2-n-butyl-MDl. Developed tension decreased by 25% (B) and 80% (C).

Fig. 11-13. Apparatus for measuring the time dependence of interfacial tension (from Ref. 34). The air and aspirator connections allow for establishing the desired level of ftesh surface. IV denotes the Wilhelmy slide, suspended from a Cahn electrobalance with a recorder output.

Occasionally, materials are tested in tension by applying the loads in increments. If this method is used for plastics then special caution is needed because during the delay between applying the load and recording the strain, the material creeps. Therefore if the delay is not uniform there may appear to be excessive scatter or non-linearity in the material. In addition, the way in which the loads are applied constitutes a loading history which can affect the performance of the material. A test in which the increments are large would quite probably give results which are different from those obtained from a test in which the increments were small or variable. 

Couplings for grades J-55, K-55 and N-80 shall conform to the tensile requirements specified in Table 4-142. A tensile test shall be made on each heat of steel from which couplings are produced, and the coupling manufacturer shall maintain a record of such tests. This record shall be open to inspection by the purchaser. Either round specimens proportioned as specified in ASTME 8 Tension Testing of Metallic Materials, or strip specimens shall be used, at the option of the manufacturer. 

Creep-test specimens may be loaded in tension or flexure (to a lesser degree in compression) in a constant temperature environment. With the load kept constant, deflection or strain is recorded at regular intervals of hours, days, weeks, months, or years. Generally, results are obtained at three or more stress levels. 

The spinning drop technique measures the shape of the oil drop in the flooding solution in a capillary tube. An automatic measuring system has been developed by combining a video-image analysis, an automatic recording system, and a computer for calculation of the interfacial tension [1865]. 

Most work on the SR and diseased smooth muscle has concerned vascular smooth muscle in hypertensive animals, and bladders from animal models of outflow obstruction. The tools used to study SR function are mainly indirect, and include recording tension or intracellular [Ca2+] with fluorescent probes, measuring Ca2+ fluxes with 45Ca, and investigating the effects of drugs known to block SERCA or activate store release. More directly, some measurement of the activity of SERCA in microsomal preparations has been undertaken (e.g. Zderic et al 1996). 

Effect on the eye. Leopold and Comroe4 recorded the actions of D.F.P. on the normal eye, expanding the earlier British work (pp. 2, 43). They confirmed the prolonged myosis lasting up to 3 weeks with a spasm of the ciliary muscle for 3-7 days. There is usually a decrease in the intra-ocular tension, although occasionally there may be a slight rise before a fall in pressure. The action outlasts that of common myotics, and a 0-1 per... 

Values of the surface tension of solutions of Paludrine as a function of concentration have been recorded (202). 

In the fiber pull-out test, a fiber(s) is partially embedded in a matrix block or thin disc of various shapes and sizes as shown in Fig 3.6. When the fiber is loaded under tension while the matrix block is gripped, the external force applied to the fiber is recorded as a function of time or fiber end displacement during the whole debond and pull-out process. There are characteristic fiber stresses that can be obtained from the typical force (or fiber stress). The displacement curve of the fiber pull-out... 

Responses of the preparation to a physiological or pharmacological stimulus can be determined by a suitable recording apparatus. Thus, narrowing of a blood vessel is recorded with the help of two clamps by which the vessel is suspended under tension. 

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