Papillary Fibroelastoma Found With Transesophageal Echocardiography After a Normal Transthoracic Echocardiography.

We present the case of a patient with transient ischemic attacks who was being investigated for multiple embolic strokes. Initial workup, including brain computed tomography, computed tomography angiography, and transthoracic echocardiography (TTE) were negative for a source until transesophageal echocardiography (TEE) found a mass in the left atrium. The TEE differentiated the mass as a rare cardiac papillary fibroelastoma on the left atrial free wall confirmed by postsurgical pathology. This case highlights the importance of TEE as a diagnostic tool for its ability to more accurately differentiate and characterize the tumor compared with TTE. This case underscores that a negative TTE does not equate to zero risk of the presence of a cardiac tumor. It is prudent for the clinician to be cognizant that it may be beneficial to perform a TEE even with a negative TTE workup.

Non-symmetric liquid crystal dimer containing a carbohydrate-based moiety.

The synthesis and characterisation of a novel non-symmetric liquid crystal dimer, 1-[3-O-(D-glucopyranos-3-yl)]-8-[(4-methoxyazobenzene-4'-oxy)]octane is reported. This exhibits glassy behaviour and a highly interdigitated smectic A phase in which the aromatic and alkyl structural fragments overlap. Variable temperature infrared spectroscopy reveals that the strength and extent of hydrogen bonding within the system does not show a marked change at either the glass transition or at the smectic A-isotropic transition. This observation indicates that the smectic A-isotropic transition is driven by changes in the van der Waals interactions between the molecules while hydrogen bonded aggregates persist into the isotropic phase.

Vacuum-deposited planar heterojunction polymer solar cells.

The vacuum thermal evaporation of poly(3-hexylthiophene) (P3HT) for application in photovoltaic cells is demonstrated. Structural changes before and after evaporation are determined using GPC, UV-vis absorption spectroscopy, NMR, and FTIR. GPC showed that the polymer molecular weight is reduced during evaporation, leading to a blue-shift of the absorption spectra. FTIR and NMR were used to examine the change in chemical structure: it was found that conjugation remains mostly intact; however, the conjugation length decreases and side chains dissociate from the backbone. Bilayer heterojunction solar cells were fabricated by sequential deposition of P3HT and C60 and the photovoltaic response measured.

Carbohydrate liquid crystals: synthesis and characterisation of the methyl-6-O-(n-acyl)-α-D-glucopyranosides.

Seven members of the methyl-6-O-(n-acyl)-α-D-glucopyranosides have been synthesised and their transitional properties determined. The undecanoyl and octadecanoyl members do not exhibit liquid crystallinity while the members having chain lengths between dodecanoyl and hexadecanoyl exhibit a monotropic smectic A phase. Variable temperature infrared spectroscopy reveals that the hydrogen bonding within the system shows a marked change at the melting point but apparently no change at the smectic A-isotropic transition. This observation is interpreted in terms of Goodby's model for the smectic A phase in which the carbohydrate moieties are located at the centre of the smectic bilayer and assuming that hydrogen bonded aggregates persist into the isotropic phase. Within this framework, the unusually low values of the entropy change associated with the smectic A-isotropic transition may also be accounted for.

SnS/PbS nanocrystal heterojunction photovoltaics.

We report advances in the growth, characterization and photovoltaic properties of SnS nanocrystals, with controlled < 10 nm size, and their inclusion into a lead chalcogenide solar cell. The SnS/PbS nanocrystalline film heterojunction is shown to display a type II band alignment, in which the direction of flow of the photocurrent depends on the order of the layers and not the relative work functions of the contacts. On placing the SnS layer next to the indium tin oxide (ITO) cathode we observe a dramatic increase in V(oc) to as much as 0.45 V. Our results suggest that SnS nanocrystal films can be used in multi-junction solar cells, that a SnS/PbS heterojunction on its own shows photovoltaic behaviour, and that a SnS layer in an ITO/SnS/PbS/Al device is acting to suppress the flow of an electron injection current.

Colloidal synthesis of lead oxide nanocrystals for photovoltaics.

Lead oxide nanocrystals are synthesised by injecting oxygen gas into an air and moisture free complex of Pb oleylamine and oleic acid in octadecene. Using various characterization methods including fabrication and testing of photovoltaic devices we explore the material properties and photovoltaic application of lead oxide nanocrystal films.