Limiting factors for charge generation in low-offset fullerene-based organic solar cells.

Free charge generation after photoexcitation of donor or acceptor molecules in organic solar cells generally proceeds via (1) formation of charge transfer states and (2) their dissociation into charge separated states. Research often either focuses on the first component or the combined effect of both processes. Here, we provide evidence that charge transfer state dissociation rather than formation presents a major bottleneck for free charge generation in fullerene-based blends with low energetic offsets between singlet and charge transfer states. We investigate devices based on dilute donor content blends of (fluorinated) ZnPc:C60 and perform density functional theory calculations, device characterization, transient absorption spectroscopy and time-resolved electron paramagnetic resonance measurements. We draw a comprehensive picture of how energies and transitions between singlet, charge transfer, and charge separated states change upon ZnPc fluorination. We find that a significant reduction in photocurrent can be attributed to increasingly inefficient charge transfer state dissociation. With this, our work highlights potential reasons why low offset fullerene systems do not show the high performance of non-fullerene acceptors.

Vacuum-Deposited Donors for Low-Voltage-Loss Nonfullerene Organic Solar Cells.

The advent of nonfullerene acceptors (NFAs) enabled records of organic photovoltaics (OPVs) exceeding 19% power conversion efficiency in the laboratory. However, high-efficiency NFAs have so far only been realized in solution-processed blends. Due to its proven track record in upscaled industrial production, vacuum thermal evaporation (VTE) is of prime interest for real-world OPV commercialization. Here, we combine the benchmark solution-processed NFA Y6 with three different evaporated donors in a bilayer (planar heterojunction) architecture. We find that voltage losses decrease by hundreds of millivolts when VTE donors are paired with the NFA instead of the fullerene C60, the current standard acceptor in VTE OPVs. By showing that evaporated small-molecule donors behave much like solution-processed donor polymers in terms of voltage loss when combined with NFAs, we highlight the immense potential for evaporable NFAs and the urgent need to direct synthesis efforts toward making smaller, evaporable compounds.

Assessing the Photovoltaic Quality of Vacuum-Thermal Evaporated Organic Semiconductor Blends.

Vacuum-thermal evaporation (VTE) is a highly relevant fabrication route for organic solar cells (OSCs), especially on an industrial scale as proven by the commercialization of organic light emitting diode-based displays. While OSC performance is reported for a range of VTE-deposited molecules, a comprehensive assessment of donor:acceptor blend properties with respect to their photovoltaic performance is scarce. Here, the organic thin films and solar cells of three select systems are fabricated and ellipsometry, external quantum efficiency with high dynamic range, as well as OTRACE are measured to quantify absorption, voltage losses, and charge carrier mobility. These parameters are key to explain OSC performance and will help to rationalize the performance of other material systems reported in literature as the authors' methodology is applicable beyond VTE systems. Furthermore, it can help to judge the prospects of new molecules in general. The authors find large differences in the measured values and find that today's VTE OSCs can reach high extinction coefficients, but only moderate mobility and voltage loss compared to their solution-processed counterparts. What needs to be improved for VTE OSCs is outlined to again catch up with their solution-processed counterparts in terms of power conversion efficiency.

Disease Spectrum and Frequency of Illness in Pediatric Emergency: A Retrospective Analysis From Karachi, Pakistan.

Background: The National Institute of Child Health (NICH) is the largest tertiary care pediatric hospital operating in Karachi, Pakistan. Its emergency department (ED) is always occupied. However, the spectrum of illness in patients presenting to this ED has not been investigated in depth to identify the most common presentations and to develop effective management for treating patients. Methods: This retrospective study included all children visiting the pediatric ED of the NICH from January 2017 through December 2017. Newborns to children 14 years of age were included, for a total cohort of 188,803 patients. Sociodemographic data and clinical information were extracted from the medical record. Univariate analysis was performed to determine the frequency and percentage for all the variables. Results: The cohort consisted of 9% (n=16,952) neonates (0 to 1 month) and 91% (n=171,351) older children (>1 month to 14 years). Among the neonates, 36.6% presented as triage level 1. Sepsis was diagnosed in 23.8% of neonates, low birth weight/preterm in 18.4%, and respiratory distress/pneumonia in 15.2%. In infants and older children, diagnoses related to the respiratory system (37.3%), gastrointestinal system (16.4%), and multisystem involvement (15.9%) were the most common. During the evening shifts, 38.1% of patients were seen, and on weekends, 51.6% of patients were seen. Sunday was the busiest day in the ED. Conclusion: The tertiary care pediatric EDs in Pakistan have witnessed an increasing number of critical emergencies over time. Respiratory and gastrointestinal emergencies form the majority of the ED burden. A surge of patients is seen on the weekends and during the evening shifts. The spectrum of illnesses should be investigated via prospective, longitudinal studies in other pediatric EDs in Pakistan to understand the trends and to provide the foundation for developing nationwide recommendations for improving pediatric emergency care.

Neonatal Purpura Fulminans, a rare genetic disorder due to protein C deficiency: A case report.

Neonatal Purpura Fulminans is a rare and fatal disorder associated with perivascular haemorrhage and disseminated intravascular coagulation. Early clinical recognition, timely investigation and treatment is utmost important. A 6 days old baby boy was brought to emergency with blackish ulcers all over the body. Initially these were over the feet and scalp but later appeared on the abdomen. On examination, child was vitally stable, mildly icteric and had multiple erythematous large bullous blackish lesions on scalp, lower abdomen, perineum, back and soles. Neonatal reflexes and systemic examination was normal. Laboratory investigations showed normal CBC, PT/APTT and Protein S level while Protein C and Antithrombin III levels were low. Neonatal Purpura Fulminans is a life threatening condition and family screening is also mandatory for early recognition of disease in the siblings.

Providing traceability for neuroimaging analyses.

INTRODUCTION: With the increasingly digital nature of biomedical data and as the complexity of analyses in medical research increases, the need for accurate information capture, traceability and accessibility has become crucial to medical researchers in the pursuance of their research goals. Grid- or Cloud-based technologies, often based on so-called Service Oriented Architectures (SOA), are increasingly being seen as viable solutions for managing distributed data and algorithms in the bio-medical domain. For neuroscientific analyses, especially those centred on complex image analysis, traceability of processes and datasets is essential but up to now this has not been captured in a manner that facilitates collaborative study. PURPOSE AND METHOD: Few examples exist, of deployed medical systems based on Grids that provide the traceability of research data needed to facilitate complex analyses and none have been evaluated in practice. Over the past decade, we have been working with mammographers, paediatricians and neuroscientists in three generations of projects to provide the data management and provenance services now required for 21st century medical research. This paper outlines the finding of a requirements study and a resulting system architecture for the production of services to support neuroscientific studies of biomarkers for Alzheimer's disease. RESULTS: The paper proposes a software infrastructure and services that provide the foundation for such support. It introduces the use of the CRISTAL software to provide provenance management as one of a number of services delivered on a SOA, deployed to manage neuroimaging projects that have been studying biomarkers for Alzheimer's disease. CONCLUSIONS: In the neuGRID and N4U projects a Provenance Service has been delivered that captures and reconstructs the workflow information needed to facilitate researchers in conducting neuroimaging analyses. The software enables neuroscientists to track the evolution of workflows and datasets. It also tracks the outcomes of various analyses and provides provenance traceability throughout the lifecycle of their studies. As the Provenance Service has been designed to be generic it can be applied across the medical domain as a reusable tool for supporting medical researchers thus providing communities of researchers for the first time with the necessary tools to conduct widely distributed collaborative programmes of medical analysis.

Research traceability using provenance services for biomedical analysis.

We outline the approach being developed in the neuGRID project to use provenance management techniques for the purposes of capturing and preserving the provenance data that emerges in the specification and execution of workflows in biomedical analyses. In the neuGRID project a provenance service has been designed and implemented that is intended to capture, store, retrieve and reconstruct the workflow information needed to facilitate users in conducting user analyses. We describe the architecture of the neuGRID provenance service and discuss how the CRISTAL system from CERN is being adapted to address the requirements of the project and then consider how a generalised approach for provenance management could emerge for more generic application to the (Health)Grid community.

Reusable services from the neuGRID project for grid-based health applications.

By abstracting Grid middleware specific considerations from clinical research applications, re-usable services should be developed that will provide generic functionality aimed specifically at medical applications. In the scope of the neuGRID project, generic services are being designed and developed which will be applied to satisfy the requirements of neuroscientists. These services will bring together sources of data and computing elements into a single view as far as applications are concerned, making it possible to cope with centralised, distributed or hybrid data and provide native support for common medical file formats. Services will include querying, provenance, portal, anonymization and pipeline services together with a 'glueing' service for connection to Grid services. Thus lower-level services will hide the peculiarities of any specific Grid technology from upper layers, provide application independence and will enable the selection of 'fit-for-purpose' infrastructures. This paper outlines the design strategy being followed in neuGRID using the glueing and pipeline services as examples.