Enhanced photogeneration of polaron pairs in neat semicrystalline donor-acceptor copolymer films via direct excitation of interchain aggregates

We investigate the photogeneration of polaron pairs (PPs) in neat films of the semicrystalline donor–acceptor semiconducting copolymer PCPDTBT. Carefully selecting the solution-processing procedures, we obtain films with different amounts of crystallinity and interchain aggregation. We compare the photogeneration of PPs between the films by monitoring their photoinduced absorption in ultrafast pump–probe experiments, selectively exciting nonaggregated or aggregated polymer chains. The direct photoexcitation of interchain π-aggregates results in prompt (<100 fs) charge generation. Compared to the case where nonaggregated chains are excited, we find an 8-fold increase in the prompt PP to singlet-exciton ratio. We also show that highly crystalline lamellar nanostructures not containing π-stacked or any light-absorbing aggregates do not improve the efficiency of PP photogeneration. Our results show that light absorption from interchain aggregates is highly beneficial for charge photogeneration in semiconducting polymers and should be taken into account when optimizing film morphologies for photovoltaic devices

The use of a new automatic device for patients' assessment at Triage in Emergency Department

Objectives: To assess time saving in an Emergency Department arising out of the introduction of automatic devices (Carescape™ V100) to measure vital signs compared to the manual devices. Methods: We performed a prospective, observational study of eligible patients referring to Sant'Andrea Hospital Emergency Department during the entire month of October 2009, randomly assigned into two groups. In the first group of 476 patients vital signs measurements were detected with manual devices, while in the second group of 477 patients with automatic device Carescape™ V100. Results: Data indicated that the comparison of the total time between the two groups gave a significant difference (1993 vs 1518 min, p < 0.001). No differences were found with respect to age, sex and priority codes. Significant differences were also found when comparing the subgroups of the same acuity categories: white codes 4.33 vs 2.27 (min), p < 0.05; green codes 4.28 vs 3.37 (min), p < 0.001; yellow codes 3.92 vs 2.72 (min), p < 0.001. Conclusions: Our data demonstrated a statistical significance between the two groups with a difference of 475 minutes spent in Triage procedures including vital signs measurements. In conclusion time saved by vital signs automatic device could allow ED physicians to make a qualified approach with an earlier diagnosis and a more rapid and effective therapy, possibly improving patients' outcomes. ABSTRACT of data concerning vital signs quality assessment, because we did not compare the two methods in the same patient and we did not correlate Triage priority evaluation with patients' outcomes. In the future further studies should be specifically aimed to address this issue. In conclusion time saved by vital signs automatic device could allow ED physicians to make a qualified approach to patient with an earlier diagnosis and a more rapid and effective therapy, possibly improving patients' outcomes

Near infrared ultrafast pump-probe spectroscopy with ZrF4-BaF2-LaF3-AlF3-NaF fiber supercontinuum

We report on the performance of a setup designed for femtosecond pump-probe spectroscopy in the near infrared (NIR) spectral region. We generate a supercontinuum (SC) probe by coupling 140 fs light pulses at 1550 nm into a ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fiber. The combined high nonlinearity and transparency of the ZBLAN fluoride glass allows us to obtain a SC probe from 1 to 2.6 μm. The NIR pulses are used to demonstrate a proof of principle experiment probing the relaxation of photo induced excitations in a conjugated polymer:fullerene blend film. The results show the possibility to perform fibre based NIR SC femtosecond spectroscopy at &gt;100 KHz repetition rate and using lasers with pulse energy just above 300 nJ

(Perylene)3-(TCNQF1)2: Yet Another Member in the Series of Perylene–TCNQFx Polymorphic Charge Transfer Crystals

The 3:2 Charge Transfer (CT) co-crystal (Perylene)3(TCNQF1)2 is grown by the Physical Vapor Transport (PVT) method, and characterized structurally and spectroscopically. Infrared analysis of the charge sensitive modes reveals a low degree of charge transfer (less than 0.1) between donor and acceptor molecules. The crystal is isostructural to the other 3:2 CT crystals formed by Perylene with TCNQF2 and TCNQF4, whereas such stoichiometry and packing is not known for the CT crystals with non-fluorinated TCNQ. The analysis of the isostructural family of 3:2 Perylene–TCNQFx (x = 1,2,4) co-crystal put in evidence the role of weak F…HC bonding in stabilizing this type of structure</jats:p

Solvatochromic covalent organic frameworks.

Covalent organic frameworks (COFs) are an emerging class of highly tuneable crystalline, porous materials. Here we report the first COFs that change their electronic structure reversibly depending on the surrounding atmosphere. These COFs can act as solid-state supramolecular solvatochromic sensors that show a strong colour change when exposed to humidity or solvent vapours, dependent on vapour concentration and solvent polarity. The excellent accessibility of the pores in vertically oriented films results in ultrafast response times below 200 ms, outperforming commercially available humidity sensors by more than an order of magnitude. Employing a solvatochromic COF film as a vapour-sensitive light filter, we demonstrate a fast humidity sensor with full reversibility and stability over at least 4000 cycles. Considering their immense chemical diversity and modular design, COFs with fine-tuned solvatochromic properties could broaden the range of possible applications for these materials in sensing and optoelectronics

High Circular Polarization of Electroluminescence Achieved via Self-Assembly of a Light-Emitting Chiral Conjugated Polymer into Multidomain Cholesteric Films.

We demonstrate a facile route to obtain high and broad-band circular polarization of electroluminescence in single-layer polymer OLEDs. As a light-emitting material we use a donor-acceptor polyfluorene with enantiomerically pure chiral side-chains. We show that upon thermal annealing the polymer self-assembles into a multidomain cholesteric film. By varying the thickness of the polymer emitting layer, we achieve high levels of circular polarization of electroluminescence (up to 40% excess of right-handed polarization), which are the highest reported for polymer OLEDs not using chiral dopants or alignment layers. Mueller matrix ellipsometry shows strong optical anisotropies in the film, indicating that the circular polarization of luminescence arises mainly after the photon has been generated, through selective scattering and birefringence correlated in the direction of the initial linear polarization of the photon. Our work demonstrates that chirally substituted conjugated polymers can combine photonic and semiconducting properties in advanced optoelectronic devices

Osteoporosis and cardiovascular diseases’ cosegregation: epidemiological features

Life expectancy in Italy is estimated to rise to 77.9 and 84.4 years in next years. Increased life expectancy is associated with a greater frailty of elderly people and an increased prevalence of chronic and degenerative illnesses such as cardiovascular diseases and osteoporosis. The impact of osteoporotic hip fractures in Italy is very similar to that of acute myocardial infarction (AMI), and there is a need for further epidemiological investigations concerning both the pathologies, as well as for a better understanding of possible mechanisms of their cosegregation. Actually, calcium metabolism is involved both in the development of osteoporosis and in the raise of cardiovascular risk. We have reviewed the most recent publications concerning epidemiological trends of both osteoporosis and acute myocardial infarction (AMI), and also the trials addressing cosegregation of these pathologies. According to the publications examined, in the Italian population (both ³ 45 and > 65 years old), the number of hospitalizations following hip fracture and AMI are comparable. Both hip fractures and cardiovascular diseases represent in Italy a serious medical problem and a leading health cost driver, according to what has already been reported for many other Countries in the industrialized world, thus requiring a global clinical approach. Low calcium intake could represent one of the possible pathogenic paths underlining the association between hypertension and osteoporosis. Low calcium serum levels has been proved to enhance PTH and vitamin D3 production, which result in a remarkable lypogenesis performed by adypocites and switch on mechanisms leading to the raise of blood systolic pressure, the development of atherosclerotic plaques and cardiovascular events. Although many trials have suggested that bone mineral density may be included in the list of cardiovascular risk factors, more studies are needed in order to deeply investigate the causal relationships between calcium metabolism and cardiovascular diseases

Extended adjuvant endocrine treatment for premenopausal women: A Delphi approach to guide clinical practice

The use of an aromatase inhibitor (AI) in combination with ovarian function suppression (OFS) has become the mainstay of adjuvant endocrine therapy in high-risk premenopausal patients with hormone receptor-positive breast cancer. Although five years of such therapy effectively reduces recurrence rates, a substantial risk of late recurrence remains in this setting. Multiple trials have shown that extending AI treatment beyond five years could offer further protection. However, as these studies comprised only postmenopausal patients, no direct evidence currently exists to inform about the potential benefits and/or side effects of extended AI + OFS therapies in premenopausal women. Given these grey areas, we conducted a Delphi survey to report on the opinion of experts in breast cancer treatment and summarize a consensus on the discussed topics. A total of 44 items were identified, all centred around two main themes: 1) defining reliable prognostic factors to pinpoint premenopausal patients eligible for endocrine therapy extension; 2) designing how such therapy should optimally be administered in terms of treatment combinations and duration based on patients' menopausal status. Each item was separately discussed and anonymously voted by 12 experts representing oncological institutes spread across Italy. The consensus threshold was reached in 36 out of 44 items (82%). Herein, we discuss the levels of agreement/disagreement achieved by each item in relation to the current body of literature. In the absence of randomized trials to guide the tailoring of extended AI treatment in premenopausal women, conclusions from our study provide a framework to assist routine clinical practice

How intermolecular geometrical disorder affects the molecular doping of donor-acceptor copolymers

Molecular doping of conjugated polymers represents an important strategy for improving organic electronic devices. However, the widely reported low efficiency of doping remains a crucial limitation to obtain high performance. Here we investigate how charge transfer between dopant and donor\u2013acceptor copolymers is affected by the spatial arrangement of the dopant molecule with respect to the copolymer repeat unit. We p-dope a donor\u2013acceptor copolymer and probe its charge-sensitive molecular vibrations in films by infrared spectroscopy. We find that, compared with a related homopolymer, a four times higher dopant/polymer molar ratio is needed to observe signatures of charges. By DFT methods, we simulate the vibrational spectra, moving the dopant along the copolymer backbone and finding that efficient charge transfer occurs only when the dopant is close to the donor moiety. Our results show that the donor\u2013acceptor structure poses an obstacle to efficient doping, with the acceptor moiety being inactive for p-type doping

Improving the Stability and Performance of Perovskite Light-Emitting Diodes by Thermal Annealing Treatment

$\textbf{A perovskite LED with a perovskite film}$ treated under optimum thermal annealing conditions exhibits a significantly enhanced long-term stability with full coverage of the green electroluminescence emission due to the highly uniform morphology of the perovskite film.This study was supported by the Mid-Career Researcher Program (2015R1A2A2A01003263). This work was fi nancially supported by the KIST-UNIST partnership program (1.150091.01/2.150464.01). This work was also supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1073051). We thank the EPSRC (UK) for support