Loop-mediated isothermal amplification (LAMP) has been developed as a versatile method for nucleic acid analysis in many applications. However, non-specific LAMP leading to false-positive outcomes has been observed frequently. To solve this problem, we selected six molecules as the additives for evaluating their effects on the improvement of the LAMP specificity. Experimental results show that bovine serum albumin (BSA) and DL-dithiothreitol (DTT) have negative effects on the LAMP specificity; dimethyl sulfoxide (DMSO), tetramethylene sulfoxide (TMSO), and glycerol could inhibit the non-specific LAMP moderately. Surprisingly, pullulan shows an ability to inhibit the non-specific amplification of LAMP significantly without affecting the sample amplification of LAMP, and this inhibitory effect is concentration dependent. Thus, pullulan could be considered as the most promising additive to improve the amplification specificity in the LAMP-based detection and analysis of nucleic acids.
In this paper we discuss the non-linear contact problem between the stator and the rotor of an ultrasonic travelling were motor. For a first simplified mathematical model the problem is formulated for a linear motor in which the stator is modelled as a Bernoulli-Euler beam and the slider (rotor) is assumed to be rigid. A thin layer of visco-elastic material is assumed to exist between stator and slider. Expressions are obtained for the contact pressure between the two parts. The frictional forces both in the sticking and in the sliding zone can then be easily obtained assuming Coulomb friction. 相似文献