Fullerene Aggregation in Thin Films of Polymer Blends for Solar Cell Applications.

We report on the effects of the film morphology on the fluorescence spectra for a thin film including a quinoxaline-based co-polymer (TQ1) and a fullerene derivative ([6,6]-phenyl-C-butyric acid methyl ester-PCBM). The ratio between the polymer and the fullerene derivative, as well as the processing solvent, were varied. Besides the main emission peak at 700 nm in the fluorescence spectra of thin films of this phase-separated blend, a broad emission band is observed with a maximum at 520⁻550 nm.

Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices.

Plasmonic Nanospectroscopy for Thermal Analysis of Organic Semiconductor Thin Films.

Organic semiconductors are key materials for the next generation thin film electronic devices like field-effect transistors, light-emitting diodes, and solar cells. Accurate thermal analysis is essential for the fundamental understanding of these materials, for device design, stability studies, and quality control because the desired nanostructures are often far from thermodynamic equilibrium and therefore tend to evolve with time and temperature. However, classical experimental techniques are insufficient because the active layer of most organoelectronic device architectures is typically only on the order of a hundred nanometers or less.

Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices.

Photo-degradation in air of the active layer components in a thiophene-quinoxaline copolymer:fullerene solar cell.

We have studied the photo-degradation in air of a blend of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1), and how the photo-degradation affects the solar cell performance. Using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, changes to the electronic structure of TQ1 and PCBM caused by illumination in ambient air are investigated and compared between the pristine materials and the blend. The NEXAFS spectra show that the unoccupied molecular orbitals of TQ1 are not significantly changed by the exposure of pristine TQ1 to light in air, whereas those of PCBM are severely affected as a result of photo-induced degradation of PCBM.

Mapping fullerene crystallization in a photovoltaic blend: an electron tomography study.

The formation of fullerene crystals represents a major degradation pathway of polymer/fullerene bulk-heterojunction thin films that inexorably deteriorates their photovoltaic performance. Currently no tools exist that reveal the origin of fullerene crystal formation vertically through the film. Here, we show that electron tomography can be used to study nucleation and growth of fullerene crystals.

T regulatory cells in B-cell malignancy - tumour support or kiss of death?

It is well established that T regulatory (Treg) cells counteract tumour immunity. However, conflicting results describing the role of Treg cells in haematological tumours warrant further investigations to clarify the interactions between Treg cells and the tumour. B-cell malignancy derives from different stages of B-cell development and differentiation in which T cells play a profound role.

Both CD4+ FoxP3+ and CD4+ FoxP3- T cells from patients with B-cell malignancy express cytolytic markers and kill autologous leukaemic B cells in vitro.

Cytotoxic CD4(+) T cells have been found in patients with chronic lymphocytic leukaemia (CLL) and seem to be involved in the regulation of malignant B cells. The CD4(+) T regulatory cells (Tregs) can regulate various immune cells, including B cells, by inducing their apoptosis. Hence, different subgroups of CD4(+) T cells may be involved in the regulation of malignant B cells.

T regulatory cells control T-cell proliferation partly by the release of soluble CD25 in patients with B-cell malignancies.

Interleukin-2 (IL-2) is one of the most studied cytokines driving T-cell proliferation, activation and survival. It binds to the IL-2 receptor consisting of three chains, the α (CD25), β and common γ (γc). The binding of the CD25 chain to IL-2 is necessary to expose high-affinity binding sites for the β and γc chains, which, in turn, are responsible for downstream signalling.

AdCD40L immunogene therapy for bladder carcinoma--the first phase I/IIa trial.

Purpose: Immunotherapy with Bacillus Calmette-Guerin (BCG) instillation is recommended for high-risk, non-muscle invasive bladder cancer. Bacillus Calmette-Guerin is not effective in advanced tumors, and better alternatives are warranted. Immunostimulating gene therapy with adenoviral vectors expressing CD40 ligand (AdCD40L) has shown efficacy in tumor models.

T regulatory cells lacking CD25 are increased in MS during relapse.

Dysregulation of inflammatory responses is considered to be a key element in autoreactive immune responses. T regulatory cells (Tregs) are important to maintain self-tolerance and the role of CD4(+)CD25(+)FoxP3(+) Tregs in autoimmunity has been extensively investigated. Recently, it was shown that Tregs in systemic lupus erythematosus lacked CD25 but were biologically functional.

Local AdCD40L gene therapy is effective for disseminated murine experimental cancer by breaking T-cell tolerance and inducing tumor cell growth inhibition.

CD40 ligand (CD40L) is one of the most potent stimulators of Th1-type immunity through its maturation of dendritic cells that, in turn, stimulate effector cells such as T cells and NK cells. Lately, CD40-mediated cell growth inhibition and apoptosis have been in focus for the development of novel cancer treatment regiments, including recombinant soluble CD40L or CD40-stimulating antibodies. In this study, intravesical CD40L gene transfer through adenoviral vectors (AdCD40L) was used to treat an aggressive model of disseminated bladder cancer (MB49/C57BL/6).