Blue organic seven segment display based on poly (9,9-dioctyfluorene)with β-phase emission

In this work, organic seven segment displays based on poly(9,9-dioctyfluorene), PFO, have been fabricated. PFO has consolidated as an attractive material for PLEDs due to its efficient blue emission [1] and high hole mobility. Additionally, PFO has a particular conformation, called β-phase associated to extended PFO chain conformation, which is of great interest for potential device applications because, among all others, it has the highest photoluminescence quantum efficiency [2] and the best colour stability [3]. The structure fabricated uses Indium Tin Oxide (ITO) as anode, Poly(3,4 -ethylenedioxythiophene) /poly(4- styrenesulfonate) (PEDOT:PSS) as hole transport layer and Ba:Al as cathode. After thoroughly cleaning the substrates (covered with ITO) a photolithography process is carried out in order to pattern the anode. Next, the organic layers (PEDOTT:PSS and PFO) are spin casted. Finally, metals (Ba~30 nm and Al~100 nm) are thermally evaporated in an atmosphere of 6x10 -6 Torr. PFO is dissolved in toluene at 1 % wt. A detailed description of the fabrication process can be found in [4]. Finally, the device is encapsulated (using an epoxy and a glass tap) and contacts are indium soldered on the pads. In figure 1, we can observe the shadow mask used for the anode photolitography process (left) and the final device lighting in a zero configuration (right)

What general practitioners need to know about patent foramen ovale

A patent foramen ovale (PFO) consists of a hole between the right and left atriums of the heart that did not close the way it should after birth. Twenty five percent of the population have a PFO, but this usually does not cause problems, because the opening is functionally closed by the difference in pressure between the heart and the chest. This study is a literature review about the clinical significance of PFO and its management in three clinical situations: cryptogenic strokes, migraine with aura and scuba divers who sustained a decompression sickness. PFOs had been linked with various medical conditions such as strokes, migraine, and with certain types of decompression sickness (DCS). In general, this association is not very well established. Young patients who sustain a cardiovascular event without a known cause (cryptogenic stroke) have resulted in the tendency to screen these patents becoming the norm and more PFOs are being closed using standard methods and devices. The association of PFOs and migraine attacks is less clear. In the case of scuba divers the risk of suffering from a decompression accident is increased if one has a PFO. The management of these patients remains difficult.peer-reviewe

Percutaneous closure of PFO in patients with reduced oxygen saturation at rest and during exercise : short- and long-term results

Background. A patent foramen ovale (PFO) is a rare cause of hypoxemia and clinical symptoms of dyspnea. Due to a right-to-left shunt, desaturated blood enters the systemic circulation in a subset of patients resulting in dyspnea and a subsequent reduction in quality of life (QoL). Percutaneous closure of PFO is the treatment of choice. Objectives. This retrospective multicentre study evaluates short- and long-term results of percutaneous closure of PFO in patients with dyspnea and/or reduced oxygen saturation. Methods. Patients with respiratory symptoms were selected from databases containing all patients percutaneously closed between January 2000 and September 2018. Improvement in dyspnea, oxygenation, and QoL was investigated using pre- and postprocedural lung function parameters and two postprocedural questionnaires (SF-36 and PFSDQ-M). Results. The average follow-up period was 36 [12-43] months, ranging from 0 months to 14 years. Percutaneous closure was successful in 15 of the 16 patients. All patients reported subjective improvement in dyspnea immediately after device deployment, consistent with their improvement in oxygen saturation (from 90 +/- 6% to 94 [92-97%] on room air and in upright position) (p<0.05). Both questionnaires also indicated an improvement of dyspnea and QoL after closure. The two early and two late deaths were unrelated to the procedure. Conclusion. PFO-related dyspnea and/or hypoxemia can be treated successfully with a percutaneous intervention with long-lasting benefits on oxygen saturation, dyspnea, and QoL

Confinement Effects on the Crystalline Features of Poly(9,9-dioctylfluorene)

Typical device architectures in polymer-based optoelectronic devices, such as field effect transistors organic light emitting diodes and photovoltaic cells include sub-100 nm semiconducting polymer thin-film active layers, whose microstructure is likely to be subject to finite-size effects. The aim of this study was to investigate effect of the two-dimensional spatial confinement on the internal structure of the semiconducting polymer poly(9,9-dioctylfluorene) (PFO). PFO melts were confined inside the cylindrical nanopores of anodic aluminium oxide (AAO) templates and crystallized via two crystallization strategies, namely, in the presence or in the absence of a surface bulk reservoir located at the template surface. We show that highly textured semiconducting nanowires with tuneable crystal orientation can be thus produced. Moreover, our results indicate that employing the appropriate crystallization conditions extended-chain crystals can be formed in confinement. The results presented here demonstrate the simple fabrication and crystal engineering of ordered arrays of PFO nanowires; a system with potential applications in devices where anisotropic optical properties are required, such as polarized electroluminescence, waveguiding, optical switching, lasing, etc

Large magnetoresistance at room-temperature in semiconducting polymer sandwich devices

We report on the discovery of a large, room temperature magnetoresistance (MR) effect in polyfluorene sandwich devices in weak magnetic fields. We characterize this effect and discuss its dependence on voltage, temperature, film thickness, electrode materials, and (unintentional) impurity concentration. We usually observed negative MR, but positive MR can also be achieved under high applied electric fields. The MR effect reaches up to 10% at fields of 10mT at room temperature. The effect shows only a weak temperature dependence and is independent of the sign and direction of the magnetic field. We find that the effect is related to the hole current in the devices.Comment: 3 pages, 4 figure

Embolic stroke of unknown source (ESUS) in patients with atrial septum defect and patent foramen ovale: difference and similarities

Introduction Paradoxical embolism from right-to-left shunt through a patent foramen ovale (PFO) is a well-characterized cause of embolic strokes of undetermined source (ESUS). In order to better understand the pathogenic role of atrial septum defects (ASD), we compared them with ESUS of high and low likelihood of being related to PFO. Methods In the Acute STroke Registry and Analysis of Lausanne (ASTRAL), we calculated prevalence of PFO and ASD in ESUS patient undergoing echocardiography, and odds ratios (OR) when to compared to non-cryptogenic strokes. Using the Risk of Paradoxical Embolism (RoPE) score, we divided cryptogenic PFO patients in high (HL-PFO, RoPE 8- 10) and low-likelihood (LL-PFO, RoPE 0-4) PFO-related stroke. We then performed univariate comparison of epidemiological, clinical and radiological variables of both group with ESUS ASD patients. Results Among all ESUS, prevalence for ASD and PFO were 1.3% and 36.8% respectively. When compared to non-cryptogenic stroke, ASD and PFO were associated with ESUS (OR of 5.2, CI= 1.6-16.6, and 2.8, CI= 2.1-3.8). Compared with HL-PFO, ASD were older, more often female, had more cardiovascular risk factors (CVRF) and silent strokes. Compared with LL-PFO, ASD group was significantly younger, more often female, and had less CVRF. No differences were found for clinical and radiological characteristics and outcome. Conclusion In ESUS, ASD seems to be a rare but significant stroke risk factor. Given that characteristics of such patients lie in-between high and low-likelihood paradoxical PFO- stroke, a thorough workup for other stroke mechanisms is warranted in ASD patients before routine ASD closure