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A comparative study of steady-state and time-resolved photoluminescence of para-sexiphenyl (PSP) films grown by organic molecular beam epitaxy (OMBE) and hot wall epitaxy (HWE) under comparable conditions is presented. Using different template substrates [mica(001) and KCl(001) surfaces] as well as different OMBE growth conditions has enabled us to vary greatly the morphology of the PSP crystallites while keeping their chemical structure virtually untouched. We prove that the broad redshifted emission band has a structure-related origin rather than being due to monomolecular oxidative defects. We conclude that the growth conditions and type of template substrate impacts substantially on the film morphology (measured by atomic force microscopy) and emission properties of the PSP films. The relative intensity of the defect emission band observed in the delayed spectra was found to correlate with the structural quality of PSP crystallites. In particular, the defect emission has been found to be drastically suppressed when (i) a KCl template substrate was used instead of mica in HWE-grown films, and (ii) in the OMBE-grown films dominated by growth mounds composed of upright standing molecules as opposed to the films consisting of crystallites formed by molecules lying parallel to the substrate. [ABSTRACT FROM AUTHOR]

Abstract: Phosphorescent (Ph) properties and charge carrier trapping have been studied in conjugated polymer CNPPP with incorporated red-emitting Btp2Ir(acac) metal–organic complex by time-resolved photoluminescence and thermally-stimulated luminescence (TSL) techniques. We characterized intrinsic Ph of CNPPP matrix and dynamics of triplet excitations of Btp2Ir(acac) confined by the polymer host. Combined studies of time and intensity dependence of guest Ph have demonstrated that the observed decrease in the Ph efficiency in CNPPP:Btp2Ir(acac) system at increasing excitation intensity is dominated by mutual host–guest triplet–triplet annihilation. We observed Ph spectral diffusion effects at 10wt.% of Btp2Ir(acac) dispersed in a polymer matrix, which is a proof for the triplet excitons migration though the manifold of triplet-emitter sites, and which governs the Ph concentration quenching effect. TSL measurements have provided direct evidence that the triplet-emitter molecules create a deep charge trap in the conjugated polymer and allowed trap characterization. [Copyright &y& Elsevier]

Organic thin-film transistors using 5, 5‴-diperfluorohexylcarbonyl-2,2′:5′,2″:5″,2‴-quaterthiophene (DFHCO-4T) as the electron conducting organic semiconductor are fabricated and the performance of these transistors with different top-contact metals is investigated. Transistors with Au source-drain top contacts attain an apparent saturation mobility of 4.6 cm2/V s, whereas this parameter is 100 times lower for similar transistors with Al/LiF top contacts. We explain this lower performance by the formation of a thin interfacial layer with poor charge injection properties resulting from a redox reaction between Al and DFHCO-4T. [ABSTRACT FROM AUTHOR]

Introduction: The bleeding assessment tool (BAT) has been developed to standardize and interpret bleeding history for mild bleeding disorders. However, a critical appraisal addressing the quality and results of validation studies is lacking. Aim: We performed a systematic review of diagnostic studies assessing the performance of the BAT in patients referred for evaluation of bleeding symptoms. Methods: The electronic database PubMed was searched from inception through July 27, 2017. Eligible publications were original studies that assessed and validated the diagnostic accuracy of bleeding questionnaires for identification of adults with mild bleeding disorders. For each study, sensitivity, specificity and diagnostic odds ratio (DOR) were calculated. Quality was assessed using the Quality Assessment of Diagnostic studies‐2 tool. To assess the influence of specific study characteristics on DOR, univariate meta‐regression analyses were performed. Results: Nine studies were included. Five studies investigating the ISTH‐BAT or other bleeding questionnaires had a moderate to low DOR. Four studies investigating Vicenza‐based BATs had a high DOR, with high specificity (>90%) and sensitivity of 59%‐85%. Study characteristics such as case‐control design, retrospective data collection and differences in reference standard were associated with optimistic estimates of diagnostic performance. Three of four studies with a high DOR had these study characteristics. Studies with good methodological quality mainly had a low DOR. Conclusion: The main advantage of the BAT is that it offers a complete and structured interview. However, the BAT is of limited diagnostic value to the workup of patients referred for bleeding evaluation in clinical practice. [ABSTRACT FROM AUTHOR]

In population pharmacokinetic (PK) models, interindividual variability is explained by implementation of covariates in the model. The widely used forward stepwise selection method is sensitive to bias, which may lead to an incorrect inclusion of covariates. Alternatives, such as the full fixed effects model, reduce this bias but are dependent on the chosen implementation of each covariate. As the correct functional forms are unknown, this may still lead to an inaccurate selection of covariates. Machine learning (ML) techniques can potentially be used to learn the optimal functional forms for implementing covariates directly from data. A recent study suggested that using ML resulted in an improved selection of influential covariates. However, how do we select the appropriate functional form for including these covariates? In this work, we use SHapley Additive exPlanations (SHAP) to infer the relationship between covariates and PK parameters from ML models. As a case‐study, we use data from 119 patients with hemophilia A receiving clotting factor VIII concentrate peri‐operatively. We fit both a random forest and a XGBoost model to predict empirical Bayes estimated clearance and central volume from a base nonlinear mixed effects model. Next, we show that SHAP reveals covariate relationships which match previous findings. In addition, we can reveal subtle effects arising from combinations of covariates difficult to obtain using other methods of covariate analysis. We conclude that the proposed method can be used to extend ML‐based covariate selection, and holds potential as a complete full model alternative to classical covariate analyses. [ABSTRACT FROM AUTHOR]

Nonlinear mixed effect (NLME) models are the gold standard for the analysis of patient response following drug exposure. However, these types of models are complex and time‐consuming to develop. There is great interest in the adoption of machine‐learning methods, but most implementations cannot be reliably extrapolated to treatment strategies outside of the training data. In order to solve this problem, we propose the deep compartment model (DCM), a combination of neural networks and ordinary differential equations. Using simulated datasets of different sizes, we show that our model remains accurate when training on small data sets. Furthermore, using a real‐world data set of patients with hemophilia A receiving factor VIII concentrate while undergoing surgery, we show that our model more accurately predicts a priori drug concentrations compared to a previous NLME model. In addition, we show that our model correctly describes the changing drug concentration over time. By adopting pharmacokinetic principles, the DCM allows for simulation of different treatment strategies and enables therapeutic drug monitoring. [ABSTRACT FROM AUTHOR]

Background and objectives Treatment of dilutional coagulopathy by transfusing fresh frozen plasma (FFP) remains sub-optimal. We hypothesized that partial replacement of transfused FFP by fibrinogen concentrate results in improved coagulant activity and haemostasis. This was tested in a controlled clinical intervention trial with patients experiencing massive bleeding during major surgery. Methods Patients undergoing major elective surgery were treated according to current protocols. When transfusion with FFP was required, patients were randomized as follows: group A received 4 units FFP and group B received 2 units FFP plus 2 g fibrinogen concentrate. Blood samples were taken before and after the intervention. Analysts were blinded to the treatment type. Results Group A (B) consisted of 21 (22) patients, in 16 (17) of whom bleeding stopped after intervention. Plasma fibrinogen increased significantly more in group B (0·57 g/l) than in group A (0·05 g/l). However, levels of prothrombin and factors VIII, IX and X increased more in group A than in group B. Rotational thromboelastometry (ROTEM) of whole blood and plasma revealed improved fibrin clot formation in group B but not in group A. Thrombin generation [calibrated automated thrombogram (CAT)] in plasma increased more in group A. Principal parameters determining whole-blood thromboelastometry were the fibrinogen level and platelet count. In vitro addition of fibrinogen and prothrombin complex concentrate to pre-intervention samples restored both ROTEM and CAT parameters. Conclusions Partial replacement of transfused FFP by fibrinogen increases fibrin clot formation at the expense of less improved thrombin generation. Coagulation factors other than fibrinogen alone are required for full restoration of haemostasis. [ABSTRACT FROM AUTHOR]

In this letter, we report on the growth of thin films of N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13H27) by organic vapor phase deposition (OVPD). Uniform films are deposited with a material utilization efficiency of 59±4% and deposition rates up to 15 Å/s. Top-contact transistors based on OVPD-grown PTCDI-C13H27 show high n-type mobilities (up to 0.3 cm2/V s) and reproducible characteristics. The influence of deposition parameters on electrical properties is discussed. [ABSTRACT FROM AUTHOR]

Amorphous indium-gallium-zinc-oxide (a-IGZO) is demonstrated as an electron transport layer (ETL) in a high-performance organic photodetector (OPD). Dark current in the range of 10 nA/cm² at a bias voltage of --2V and a high photoresponse in the visible spectrum were obtained in inverted OPDs with poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester active layer. The best results were obtained for the optimum a-IGZO thickness of 7.5 nm with specific detectivity of 3 x 1012 Jones at the wavelength of 550 nm. The performance of the best OPD devices using a-IGZO was shown to be comparable to state-of-the-art devices based on TiOx as ETL, with higher rectification achieved in reverse bias. Yield and reproducibility were also enhanced with a-IGZO, facilitating fabrication of large area OPDs. Furthermore, easier integration with IGZO-based readout backplanes can be envisioned, where the channel material can be used as photodiode buffer layer after additional treatment. [ABSTRACT FROM AUTHOR]