The heme compound found in deoxyribonucleic acid (DNA) extracted from bloodstains, which is regarded as a major inhibitor of polymerase chain reaction (PCR), was characterized in comparison with alkaline and acid hematin, histidine and ammonia hemochromogens, and globin and serum albumin hemochromogens digested by proteinase K. Alkaline and acid hematin were almost completely removed by phenol/chloroform treatment and ethanol precipitation, so as not to be copurified with DNA from the specimens. Spectrophotometric results indicated that the contaminant was likely to be the product of proteinase K digestion of some heme-blood protein complex, which was not completely extracted by organic solvents and remained in the ethanol precipitates of DNA. The results of polyacrylamide gradient gel electrophoresis and intensity of the inhibition of PCR suggested that the ligand of the contaminant was a somewhat large molecule, resistant to the proteolysis by proteinase K. The addition of bovine serum albumin to the reaction mixture prevented the inhibition of PCR by the heme compounds, probably by binding to the heme. This showed that the inhibition was not due to the irreversible inactivation of the enzyme.

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Multilayer piezoelectric actuators when driven under high frequency, generate significant heat, which influences the reliability and other piezoelectric properties. In this paper, heat generation in various types of multilayer PZT‐based actuators was studied. Experimental results showed that heat generation is mainly caused by ferroelectric hysteresis loss in the stress‐free state. A simplified analytic method was established to evaluate the temperature rise, which is useful for the design of multilayer and other high‐power actuators.

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This paper presents an analysis of the jumping and dropping phenomena of piezoelectric transducers, using the electrical equivalent circuit constants at high vibration amplitude levels of resonance based on the electrical transient response technique. The calculated frequency characteristics well simulated the measured ones driven by a constant voltage source. It is clarified from the results that the jumping and dropping phenomena are caused mainly by the nonlinear behavior of the elastic constant at high vibration amplitude levels. The effects of the loss, the voltage and the driving method are also discussed.

Stability of the piezoelectric properties with changing vibration level was studied in lead zirconate-titanate (PZT) ceramics by using the constant-currenthelocity driving method. The changes of Young's modulus Y t and mechanical loss factor Q;' are a function of the square of effective vibration velocity v,,. The nonlinear proportional constants of the above functions indicate the degree of stability under vibration level change. The stability of PZT estimated by these constants coincides with the results obtained through the heat generation study.

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