Three-terminal devices to examine single-molecule conductance switching.

We report electronic transport measurements of single-molecule transistor devices incorporating bipyridyl-dinitro oligophenylene-ethynylene dithiol (BPDN-DT), a molecule known to exhibit conductance switching in other measurement configurations. We observe hysteretic conductance switching in 8% of devices with measurable currents and find that dependence of the switching properties on gate voltage is rare when compared to other single-molecule transistor devices. This suggests that polaron formation is unlikely to be responsible for switching in these devices. We discuss this and alternative switching mechanisms.

Controlling charge injection in organic field-effect transistors using self-assembled monolayers.

We have studied charge injection across the metal/organic semiconductor interface in bottom-contact poly(3-hexylthiophene) (P3HT) field-effect transistors, with Au source and drain electrodes modified by self-assembled monolayers (SAMs) prior to active polymer deposition. By using the SAM to engineer the effective Au work function, we markedly affect the charge injection process. We systematically examine the contact resistivity and intrinsic channel mobility and show that chemically increasing the injecting electrode work function significantly improves hole injection relative to untreated Au electrodes.

Kondo resonances and anomalous gate dependence in the electrical conductivity of single-molecule transistors.

We report Kondo resonances in the conduction of single-molecule transistors based on transition metal coordination complexes. We find Kondo temperatures in excess of 50 K, comparable to those in purely metallic systems. The observed gate dependence of the Kondo temperature is inconsistent with observations in semiconductor quantum dots and a simple single-dot-level model. We discuss possible explanations of this effect, in light of electronic structure calculations.

Inelastic electron tunneling via molecular vibrations in single-molecule transistors.

In single-molecule transistors, we observe inelastic cotunneling features that correspond energetically to vibrational excitations of the molecule, as determined by Raman and infrared spectroscopy. This is a form of inelastic electron tunneling spectroscopy of single molecules, with the transistor geometry allowing in situ tuning of the electronic states via a gate electrode. The vibrational features shift and change shape as the electronic levels are tuned near resonance, indicating significant modification of the vibrational states. When the molecule contains an unpaired electron, we also observe vibrational satellite features around the Kondo resonance.

[Analysis of fenoterol efficacy given as an aerosol using various mouth pieces]. / Analiza skutecznosci fenoterolu podawanego w aerozolu przy uzyciu róznych ustników.

The effect of different mouth pieces on efficacy of fenoterol was studied in 40 patients with atopic and non-atopic bronchial asthma with reversible bronchial constriction. Four devices were studied: standard MDI unit, MDI unit with Boehringer and Astra mouth pieces, MDI unit with spacer. PEF values were registered 7 hours following inhalation. Statistical differences were not significant within the whole group. In selected older patients (above 60 years of age) spacer and Astra mouth pieces produced significant changes.

[Gold salts in the treatment of bronchial asthma]. / Sole zlota w leczeniu astmy oskrzelowej.

Gold salts are used mainly in the therapy of rheumatoid diseases. Thanks to their immunoregulative and antiinflammatory properties they may be used in treatment of chronic bronchial asthma. In order to study the efficacy of gold salts in such therapy the authors studied the effect of Solganal B (Schering) in 8 patients with chronic steroid dependent bronchial asthma. In 6 patients a clinical improvement was observed enabling to lower the steroid dose. Basing on this pilot study we believe that gold salts have an beneficial effect on the course of chronic bronchial asthma.