High-Resolution Sonography: A New Technique to Detect Nerve Damage in Leprosy

Mycobacterium leprae, which causes leprosy, infects peripheral nerves resulting in functional impairment, ulcer formation and stigmatizing deformities. Early diagnosis of nerve involvement is important to avoid nerve related complications. We used non-invasive, high-resolution sonography (US) and color Doppler (CD) imaging to study the ulnar (UN), median (MN), lateral popliteal (LP) and posterior tibial (PT) nerves in 20 leprosy patients and compared 30 healthy Indian controls. The nerves were significantly thicker in the patients (p<0.0001 for each nerve). One of the key signs of leprosy is the presence of enlarged nerves. The kappa for clinical palpation and nerve enlargement by sonography was 0.30 for all examined nerves. Increased neural vascularity, the sign of inflammation was observed in 26% (39/152) of nerves by CD imaging. Increased CD was observed in multiple nerves in 3 of 4 patients with type 2 reaction. Significant correlation was observed between clinical parameters of grade of thickening, sensory loss and muscle weakness and US abnormalities of nerve echotexture, endoneural flow and cross-sectional area (p<0.001). We conclude that sonography is a better diagnostic tool to predict nerve damage as compared to clinical assessment. Nerve damage was sonographically more extensive and was observed in nerves considered clinically normal

Crystallinity Effects in Sequentially Processed and Blend-Cast Bulk-Heterojunction Polymer/Fullerene Photovoltaics

Although most polymer/fullerene-based solar cells are cast from a blend of the components in solution, it is also possible to sequentially process the polymer and fullerene layers from quasi-orthogonal solvents. Sequential processing (SqP) not only produces photovoltaic devices with efficiencies comparable to the more traditional bulk heterojunction (BHJ) solar cells produced by blend casting (BC) but also offers the advantage that the polymer and fullerene layers can be optimized separately. In this paper, we explore the morphology produced when sequentially processing polymer/fullerene solar cells and compare it to the BC morphology. We find that increasing polymer regioregularity leads to the opposite effect in SqP and BC BHJ solar cells. We start by constructing a series of SqP and BC solar cells using different types of poly(3-hexylthiophene) (P3HT) that vary in regioregulary and polydispersity combined with [6,6]-phenyl-C61-butyric-acid-methyl-ester (PCBM). We use grazing incidence wide-angle X-ray scattering to demonstrate how strongly changes in the P3HT and PCBM crystallinity upon thermal annealing of SqP and BC BHJ films depend on polymer regioregularity. For SqP devices, low regioregularity P3HT films that possess more amorphous regions allow for more PCBM crystallite growth and thus show better photovoltaic device efficiency. On the other hand, highly regioregular P3HT leads to a more favorable morphology and better device efficiency for BC BHJ films. Comparing the photovoltaic performance and structural characterization indicates that the mechanisms controlling morphology in the active layers are fundamentally different for BHJs formed via SqP and BC. Most importantly, we find that nanoscale morphology in both SqP and BC BHJs can be systematically controlled by tuning the amorphous fraction of polymer in the active layer. © 2014 American Chemical Society

Organic Solar Cells Based on Three-Dimensionally Percolated Polythiophene Nanowires with Enhanced Charge Transport

The influence of micrometer-scale poly(3-hexylthiophene) (P3HT) nanowires (NWs) and P3HT nanocrystals (NCs) on the photocurrent generation in photoactive layers having various thickness values was investigated. Self-organizing P3HT NWs were fabricated using a marginal solvent. Transmission electron microtomography was used to characterize the vertical and horizontal crystalline morphologies of the NW&apos;s and their intergrain percolation networks in the active layers. The interpenetrating P3HT NWs promoted charge transport, as demonstrated by the enhanced percolation probability and the reduction in bimolecular recombination. The photovoltaic performances were enhanced as the photoactive layer thickness increased because internal quantum efficiencies of the solar devices prepared with active layers having NW&apos;s were maintained with varying thicknesses, suggesting that the conversion of absorbed photons into a photocurrent proceeded efficiently. By contrast, the photovoltaic performances of an NC-only photoactive layer were reduced by the increase in thickness due to its poorly developed percolation pathways. The incorporation of P3HT NWs into the P3HT:indene-C-60 bisadduct photoactive layers yielded a device power conversion efficiency (PCE) of 5.42%, and the photocurrent did not decrease significantly up to a thickness of 600 nm, resulting in a PCE of 3.75%, 70% of the maximum PCE of 5.42%