Examining thermal transport through a frequency-domain representation of time-domain thermoreflectance data.

Laser-based time-domain thermoreflectance (TDTR) and frequency-domain thermoreflectance (FDTR) techniques are widely used for investigating thermal transport at micro- and nano-scales. We demonstrate that data obtained in TDTR measurements can be represented in a frequency-domain form equivalent to FDTR, i.e.

Direct measurement of room-temperature nondiffusive thermal transport over micron distances in a silicon membrane.

The "textbook" phonon mean free path of heat carrying phonons in silicon at room temperature is ∼40  nm. However, a large contribution to the thermal conductivity comes from low-frequency phonons with much longer mean free paths. We present a simple experiment demonstrating that room-temperature thermal transport in Si significantly deviates from the diffusion model already at micron distances.

Phonons in slow motion: dispersion relations in ultrathin Si membranes.

We report the changes in dispersion relations of hypersonic acoustic phonons in free-standing silicon membranes as thin as ∼8 nm. We observe a reduction of the phase and group velocities of the fundamental flexural mode by more than 1 order of magnitude compared to bulk values. The modification of the dispersion relation in nanostructures has important consequences for noise control in nano- and microelectromechanical systems (MEMS/NEMS) as well as opto-mechanical devices.

Enhanced light extraction in ITO-free OLEDs using double-sided printed electrodes.

We show how nanoimprint lithographic techniques are particularly suited for the realization of OLED device structures. We tested them to realize nanopatterned metallic electrodes containing photonic crystals to couple the light out and plasmonic crystals showing extraordinary transmission. At similar current densities, a two-fold electroluminescence is achieved with devices having double-sided structured metallic electrodes as compared to a control OLED with an ITO anode.

Aldosterone responsiveness of the epithelial sodium channel (ENaC) in colon is increased in a mouse model for Liddle's syndrome.

Liddle's syndrome is an autosomal dominant form of human hypertension, caused by gain-of-function mutations of the epithelial sodium channel (ENaC) which is expressed in aldosterone target tissues including the distal colon. We used a mouse model for Liddle's syndrome to investigate ENaC-mediated Na+ transport in late distal colon by measuring the amiloride-sensitive transepithelial short circuit current (Delta I SC-Ami) ex vivo. In Liddle mice maintained on a standard salt diet, Delta I SC-Ami was only slightly increased but plasma aldosterone (P Aldo) was severely suppressed.

PGE2 stimulates Cl- secretion in murine M-1 cortical collecting duct cells in an autocrine manner.

Prostaglandin E2 (PGE2) is thought to be an important modulator of renal ion and water transport, but its effects remain complex and incompletely understood. Here we examined the effects of PGE2 on transepithelial ion transport of M-1 mouse cortical collecting duct cells using short-circuit current (ISC) measurements. Basolateral addition of PGE2 (1 microM) produced a transient peak increase in ISC of 6.

Additional disruption of the ClC-2 Cl(-) channel does not exacerbate the cystic fibrosis phenotype of cystic fibrosis transmembrane conductance regulator mouse models.

Cystic fibrosis is a fatal inherited disease that is caused by mutations in the gene encoding a cAMP-activated chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR). It has been suggested that the cystic fibrosis phenotype might be modulated by the presence of other Cl(-) channels that are coexpressed with CFTR in some epithelial cells. Because the broadly expressed plasma membrane Cl(-) channel, ClC-2, is present in the tissues whose function is compromised in cystic fibrosis, we generated mice with a disruption of both Cl(-) channel genes.

Basolateral adrenoceptor activation mediates noradrenaline-induced Cl- secretion in M-1 mouse cortical collecting duct cells.

Noradrenaline (NA) released from efferent renal sympathetic nerves may directly affect renal tubular transport. Here we examined the effect of NA on transepithelial ion transport of cultured M-1 mouse cortical collecting duct cells using equivalent short-circuit current ( I(SC)) measurements. Steady-state I(SC) averaged 87.

Basolateral PAR-2 receptors mediate KCl secretion and inhibition of Na+ absorption in the mouse distal colon.

Proteinase-activated receptor-2 (PAR-2) may participate in epithelial ion transport regulation. Here we examined the effect of mouse activating peptide (mAP), a specific activator of PAR-2, on electrogenic transport of mouse distal colon using short-circuit current (I(SC)) measurements. Under steady-state conditions, apical application of amiloride (100 microM) revealed a positive I(SC) component of 74.