In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA.

Creep experiments on cellular glass under a constant compressive load are monitored by acoustic emission. The statistical analysis of the acoustic signals emitted by the sample while stress is being internally redistributed shows that the distribution of amplitudes follows a power law, N(A)ϳA Ϫ␤ , with ␤ϭ2.0 independent of the load. Similarly, the interarrival times between two recorded events are also distributed via a power law, Ϫ␥ , where ␥ϭ1.3. Finally, the distribution of the spatial distance between two consecutive events also shows scale invariance, (r)ϳr Ϫ with, under additional assumptions, ϭ1.6. ͓S0163-1829͑98͒09909-3͔

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a-Si:H is prepared by vacuum evaporation of Si from a crucible kept at high positive potential relative to the substrate. The concomitant bombardment of the growing film surface with ionized vapor atoms (Si+) is found to activate the incorporation of hydrogen atoms cracked off from residual water molecules (pressure=2×10−7 Torr); a-Si:H containing up to 25 at. % of H may thus be obtained. The dark conductivity changes from activated behavior (low conductivity) to hopping (high conductivity) behavior by screening off this bombardment, while the dangling bond content (2×1017<Ns <1018 cm−3), as determined by electron-spin resonance, does not change within an order of magnitude. The hydrogen incorporation into the Si structure is studied by infrared absorption, revealing most of the incorporated hydrogen to prevail near the void surfaces in the Si–H2 configuration. The results point at the existence of an inhomogeneous film structure (microstructure), the specific features of which are controlled by the ion bombardment.

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