Modelling of polymer-carbon nanotube heterojunctions for photovoltaic applications

115 p.Semiconducting single-walled carbon nanotubes (s-SWNT) are promising materialsfor efficient organic photovoltaics (OPVs). Unfortunately, the implementation of s-SWNTs has so far not lead to the expected increase in power conversion efficienciesof OPVs. For this reason, we want to study the electronic processes within polymer-SWNT heterojunctions. Transient spectroscopy provides direct information aboutphotoexcitation processes in blends. We modelled the transient spectrum of apolymer:fullerene:s-SWNT blend using Linear Response. Based on our results, weare able to explain the structure transient spectra of s-SWNT systems and theelectronic dynamics linked to it. Further, we studied the internal quantum efficiencyof different donor/acceptor blends by carrying out calculations of the Landauer-Bütticker conductance of prototypical donor/acceptor heterojunctions. We find adependence of the conductivity on the level alignment. By improving the levelalignment of the polymer and SWNT through the use of larger band gap SWNTs,one may obtain a dramatic improvement in OPV efficiency. In summary, our resultsprovide a deeper insight into the photoexcitation and electronic processes ofpolymer-carbon nanotube heterojunctions and thus support the development of moreefficient polymer-SWNT OPVs

Polycentricity and metropolitan governance. A Swiss case study

The concept of ‘polycentric spatial development’, a central principle of the European Spatial Development Perspective, is closely linked to the concept of ‘sustainable urban development’. But ‘polycentricity’ has different significance at different spatial scales. Within a European context, polycentricity can refer to functional connectivity (supported by developments in ICT and transportation), between global “gateway” cities such as London, Paris and Frankfurt on the one hand, and the utilisation of global economic and knowledge flows coming into these cities for the benefit of other EU cities and regions on the other hand. At a finer geographical scale, ‚polycentricity’ refers to outward diffusion from major cities to smaller ones over a wide area, and focuses on the local linkages that arise from this process. POLYNET is a joint research program of eight European university institutes, funded by the EU program Interreg IIIB Northwestern Europe (NWE). The project is focusing attention on a new phenomenon as far as it refers to the polycentric ‘Mega-City-Region’ in NWE which in turn is characterised by connectivity in an ‘information’ or ‘network’ society. POLYNET examines functional relationships and information flows (material/transportation and virtual/ICT) associated with service sector business activity (banking, insurance, law, accounting, advertising, logistics, management and design consulting) within and between eight major Northwest European polycentric ‘Mega-City-Regions’: South East England; Delta Metropolis, Netherlands; Rhine-Main, Germany; Île-de-France; Dublin, Ireland; Northern Switzerland / Zurich; Rhine-Ruhr, Germany and Brussels, Belgium. The paper first presents the methodological and empirical approaches applied, secondly identifies the polycentric patterns of the European Metropolitan Region of Northern Switzerland / Zurich. A third section describes the analysis of connectivity and inter-relationship of the metropolitan region of Northern Switzerland with regard to other polycentric metropolitan regions. Section four presents an outlook on potential implications for sustainable management of the metropolitan region of Northern Switzerland.

Locoregional Failure Analysis in Head-and-Neck Cancer Patients Treated with IMRT

Purpose:: Purpose: Analysis of locoregional failure in head-and-neck cancer (HNC) following intensity-modulated radiation therapy (IMRT), with focus on the location of locoregional failures in relation to the chosen planning target volumes (PTVs) and dose distributions. Patients and Methods:: Between January 2002 and May 2006, 280 HNC patients were subjected to IMRT at the authors' institution. Mean follow-up was 23.2 months (3-59.3 months). Definitive IMRT was performed in 75% of all patients. In 71%, simultaneous cisplatin-based chemotherapy was given. 70% of patients presented with T3/4, T1-2 N2c/3 or recurred disease. Locoregional failure patterns were analyzed. Results:: 2-year local, nodal, distant, disease-free, and overall survival rates were 80%, 87%, 87%, 73%, and 82%, respectively. 46 local (16%) and 31 nodal (11%) failures have been observed so far. Local tumor persistence was seen in 23/46 cases (50%), and nodal persistence in 12/31 (39%), respectively. One marginal local failure developed in a patient referred for a recurred oral cavity tumor. Three nodal failures developed outside the PTVs at unexpected locations. All other failures have been confirmed "in field”. No failure occurred in level Ib or upper level II. Local failure occurred mainly following definitive IMRT for large tumors, nodal failure only in nodally positive patients with nodal high-risk features. Conclusion:: The dose-volume concept as used here has shown to be adequate, with disease failure developing at the site of the initial gross tumor manifestation inside the boost volum

Prediction of Distant Metastasis in Head Neck Cancer Patients: Implications for Induction Chemotherapy and Pre-treatment Staging?

Background and Purpose: : Intensity modulated radiation therapy (IMRT) combined treatment approaches, surgical and radiodiagnostic advances, respectively, lead to improved local-regional control in head neck cancer (HNC). With increasing local-regional control, distant metastases (DM) become more meaningful. In some trials without concomitant chemotherapy, induction chemotherapy (IC) resulted in an absolute reduction of DM by ~10-15%. In order to define a more efficient selection of patients at risk for DM with respect to IC and M-staging, we analysed our patients treated by contemporary standards. Patients and Methods: : Between 1/2002 to 12/2007, 409 HNC patients were treated with IMRT; 303/409 (74%) underwent definitive, 106 (26%) postoperative IMRT. The mean/median follow-up was 23/20 months (3-72). 70% tolerated 4-7, 9% 1-3 cycles of simultaneous cisplatin. Treatment followed a prospectively designed protocol. In a previous study with 172 HNC IMRT patients, gross tumor volume (GTV) was found the strongest predictor for local-regional control. In the current study, this criterion has been prospectively tested for DM. Numbers needed to treat were calculated for IC. Results: : DM developed in 28/399 (7%) patients; 10 presented initially with DM (total 38/409). In 13/28 (46%), DM remained the only manifestation of disease. GTV was the strongest predictor for DM (p 70 cc; only 6 of them (6/73, 8%) developed isolated DM. Conclusion: : GTV was the most significant predictor for DM, that could guide selective pre-treatment M-staging. The subgroup with isolated DM in the high risk group, that could benefit from IC, is smal

Anticipating and Coordinating Voltage Control for Interconnected Power Systems

This paper deals with the application of an anticipating and coordinating feedback control scheme in order to mitigate the long-term voltage instability of multi-area power systems. Each local area is uniquely controlled by a control agent (CA) selecting control values based on model predictive control (MPC) and is possibly operated by an independent transmission system operator (TSO). Each MPC-based CA only knows a detailed local hybrid system model of its own area, employing reduced-order quasi steady-state (QSS) hybrid models of its neighboring areas and even simpler PV models for remote areas, to anticipate (and then optimize) the future behavior of its own area. Moreover, the neighboring CAs agree on communicating their planned future control input sequence in order to coordinate their own control actions. The feasibility of the proposed method for real-time applications is explained, and some practical implementation issues are also discussed. The performance of the method, using time-domain simulation of the Nordic32 test system, is compared with the uncoordinated decentralized MPC (no information exchange among CAs), demonstrating the improved behavior achieved by combining anticipation and coordination. The robustness of the control scheme against modeling uncertainties is also illustrated

Polycentricity and metropolitan governance. A Swiss case study

The concept of ‘polycentric spatial development’, a central principle of the European Spatial Development Perspective, is closely linked to the concept of ‘sustainable urban development’. But ‘polycentricity’ has different significance at different spatial scales. Within a European context, polycentricity can refer to functional connectivity (supported by developments in ICT and transportation), between global “gateway” cities such as London, Paris and Frankfurt on the one hand, and the utilisation of global economic and knowledge flows coming into these cities for the benefit of other EU cities and regions on the other hand. At a finer geographical scale, ‚polycentricity’ refers to outward diffusion from major cities to smaller ones over a wide area, and focuses on the local linkages that arise from this process. POLYNET is a joint research program of eight European university institutes, funded by the EU program Interreg IIIB Northwestern Europe (NWE). The project is focusing attention on a new phenomenon as far as it refers to the polycentric ‘Mega-City-Region’ in NWE which in turn is characterised by connectivity in an ‘information’ or ‘network’ society. POLYNET examines functional relationships and information flows (material/transportation and virtual/ICT) associated with service sector business activity (banking, insurance, law, accounting, advertising, logistics, management and design consulting) within and between eight major Northwest European polycentric ‘Mega-City-Regions’: South East England; Delta Metropolis, Netherlands; Rhine-Main, Germany; Île-de-France; Dublin, Ireland; Northern Switzerland / Zurich; Rhine-Ruhr, Germany and Brussels, Belgium. The paper first presents the methodological and empirical approaches applied, secondly identifies the polycentric patterns of the European Metropolitan Region of Northern Switzerland / Zurich. A third section describes the analysis of connectivity and inter-relationship of the metropolitan region of Northern Switzerland with regard to other polycentric metropolitan regions. Section four presents an outlook on potential implications for sustainable management of the metropolitan region of Northern Switzerland

PFO-BPy solubilizers for SWNTs: Modelling of polymers from oligomers

arXiv:1411.3275v1Due to their exeptional physical properties, single walled carbon nanotubes (SWNTs) embedded in organic polymers (polymer-SWNT hybrid systems) are promising materials for organic photovoltaic devices. Already at the SWNT sorting and debundling step, polymers such as the copolymer of 9,9-dioctylfluorenyl-2,7-diyl and bipyridine (PFO-BPy) are used as solubilizers. However, to model polymer-SWNT hybrid systems, we must first determine the smallest oligomer needed to sufficiently describe the electronic and optical absorption properties of the polymer. To do so, we use time dependent density functional theory (TDDFT) to model the PFO-BPy polymer using the monomers, dimers and trimers of the PFO-BPy and Py-PFO-Py building blocks, which are also compared to the infinitely long polymer. We find the Py-PFO-Py monomer, with shortened side chains, already describes the PFO-BPy polymer within the expected accuracies of TDDFT.We acknowledge funding from the European Projects DYNamo (ERC-2010-AdG-267374), CRONOS (280879-2CRONOS CP-FP7) and POCAONTAS (FP7-PEOPLE-2012-ITN-316633); Spanish Grants (FIS2012-37549-C05-02, FIS2010- 21282-C02-01, PIB2010US-00652, JCI-2010-08156); and Grupos Consolidados UPV/EHU del Gobierno Vasco (IT-319-07).Peer Reviewe

IMRT in Hypopharyngeal Tumors

Background and Purpose:: Intensity-modulated radiation therapy (IMRT) data on hypopharyngeal cancer (HC) are scant. In this study, the authors report on early results in an own HC patient cohort treated with IMRT. A more favorable outcome as compared to historical data on conventional radiation techniques was expected. Patients and Methods:: 29 consecutive HC patients were treated with simultaneous integrated boost (SIB) IMRT between 01/2002 and 07/2005 (mean follow-up 16 months, range 4-44 months). Doses of 60-71 Gy with 2.0-2.2 Gy/fraction were applied. 26/29 patients were definitively irradiated, 86% received simultaneous cisplatin-based chemotherapy. 60% presented with locally advanced disease (T3/4 Nx, Tx N2c/3). Mean primary tumor volume measured 36.2 cm3 (4-170 cm3), mean nodal volume 16.6 cm3 (0-97 cm3). Results:: 2-year actuarial local, nodal, distant control, and overall disease-free survival were 90%, 93%, 93%, and 90%, respectively. In 2/4 patients with persistent disease (nodal in one, primary in three), salvage surgery was performed. The mean dose to the spinal cord (extension of > 5-15 mm) was 26 Gy (12-38 Gy); the mean maximum (point) dose was 44.4 Gy (26-58.9 Gy). One grade (G) 3 dysphagia and two G4 reactions (laryngeal fibrosis, dysphagia), both following the schedule with 2.2 Gy per fraction, have been observed so far. Larynx preservation was achieved in 25/26 of the definitively irradiated patients (one underwent a salvage laryngectomy); 23 had no or minimal dysphagia (G0-1). Conclusion:: Excellent early disease control and high patient satisfaction with swallowing function in HC following SIB IMRT were observed; these results need to be confirmed based on a longer follow-up period. In order to avoid G4 reactions, SIB doses of < 2.2 Gy/fraction are recommended for large tumors involving laryngeal structure