Polarization Modulation in Ferroelectric Organic Field-Effect Transistors

The polarization modulation effect of the gate dielectric on the performance of metal-oxide-semiconductor field-effect transistors has been investigated for more than a decade. However, there are no comparable studies in the area of organic field-effect transistors (FETs) using polymer ferroelectric dielectrics, where the effect of polarization rotation by 90 is examined on the FET characteristics. We demonstrate the effect of polarization rotation in a relaxor ferroelectric dielectric, poly(vinylidene fluoride trifluorethylene) (PVDF-TrFE), on the performance of small-molecule-based organic FETs. The subthreshold swing and other transistor parameters in organic FETs can be controlled in a reversible fashion by switching the polarization direction in the PVDF-TrFE layer. X-ray diffraction and electron microscopy images from PVDF-TrFE reveal changes in the ferroelectric phase and domain size, respectively, upon rotating the external electric field by 90. The structural changes corroborate density-functional-theoretical studies of an oligomer of the ferroelectric molecule in the presence of an applied electric field. The strategies enumerated here for polarization orientation of the polymer ferroelectric dielectric are applicable for a wide range of polymeric and organic transistors

Landscape Planning and Ecological Networks. Part A. A Rural System in Nuoro, Sardinia

Urban-rural landscape planning research is nowadays focusing on strategies and tool s that support practitioners in designing integrated spaces starting from the analys is of local areas, where human and natural pressures interfere. A prominent framework is provided by the ecological networks, whose design regards the combination of a set of green areas or patches (the nodes) interconnected through environmental corridors (the edges). Ecological networks are useful for biodiversity protection and enhancement, as they are able to counteract fragmentation, and to create or strengthen relations and exchanges among otherwise isolated elements. Biodiversity evolution, indeed, depends on the quantity and quality of spatial cohesion of natural areas. In this paper, we aim at designing an ecological network for the periurban area on the town of Nuoro in central Sardinia. The narrative unfolds in two parts. Part A is presented in this paper and includes its methodological premises, i.e. biodiversity conservation and ecological network analysis and design, and the introductory elements of a spatial analysis on a pilot ecological network of one hundred patches. We locate patches by focusing on the ecosystems supported by the target vegetal species holmoak (Quercus ilex) and cultivated or wild olive (Olea europaea var. sativa, O. europaea var. sylverstis). These are very common plants species in the municipality and some animal species are active as seed dispersal. The reminder, i.e. Part B, of the essay is presented in an homonymous paper that focuses on the illustration of the network analys is conceived as a monitoring system and, in future perspective, as a planning support system

Urban–rural ecological networks for landscape planning

Abstrac

Bioinspired Peptide Nanostructures for Organic Field-Effect Transistors

Peptide-based nanostructures derived from natural amino acids are superior building blocks for biocompatible devices as they can be used in a bottom-up process without the need for expensive lithography. A dense nanostructured network of l,l<i>-</i>diphenylalanine (FF) was synthesized using the solid–vapor-phase technique. Formation of the nanostructures and structure–phase relationship were investigated by electron microscopy and Raman scattering. Thin films of l,l-diphenylalanine micro/nanostructures (FF-MNSs) were used as the dielectric layer in pentacene-based field-effect transistors (FETs) and metal–insulator–semiconductor diodes both in bottom-gate and in top-gate structures. Bias stress studies show that FF-MNS-based pentacene FETs are more resistant to degradation than pentacene FETs using FF thin film (without any nanostructures) as the dielectric layer when both are subjected to sustained electric fields. Furthermore, it is demonstrated that the FF-MNSs can be functionalized for detection of enzyme–analyte interactions. This work opens up a novel and facile route toward scalable organic electronics using peptide nanostructures as scaffolding and as a platform for biosensing

Une mise à jour sur les agents neurotoxiques: ce que le premier répondant, l’anesthésiologiste et l’intensiviste doivent savoir

The purpose of this review article is to familiarize first responders, anesthesiologists, and intensivists with the medical management of patients exposed to nerve agents. This review is based on the current medical literature available to the general medical community. Nerve agents are some of the deadliest substances known to humanity. Though they kill primarily via muscle paralysis, which leads to respiratory arrest, these agents affect virtually every organ system in the body. Their primary mechanism of action is the body-wide inhibition of cholinesterases. This inhibition leads to the accumulation of acetylcholine, stimulating both nicotinic and muscarinic receptors. After decontamination, the primary treatment is with atropine to control muscarinic symptoms and with oximes to reactivate the cholinesterases and treat the nicotinic symptoms. Atropine doses can be much higher than conventionally used. Seizures are generally best treated with benzodiazepines. Patients with substantial exposure may require ventilatory and intensive care unit support for prolonged periods of time. While it is unlikely that most medical practitioners will ever encounter nerve agent poisoning, it is critical to be aware of the presenting symptoms and how best to treat patients exposed to these deadly agents. History has shown that rapid medical treatment can easily mean the difference between life and death for a patient in this situation

BJS commission on surgery and perioperative care post-COVID-19

Background: Coronavirus disease 2019 (COVID-19) was declared a pandemic by the WHO on 11 March 2020 and global surgical practice was compromised. This Commission aimed to document and reflect on the changes seen in the surgical environment during the pandemic, by reviewing colleagues experiences and published evidence. Methods: In late 2020, BJS contacted colleagues across the global surgical community and asked them to describe how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had affected their practice. In addition to this, the Commission undertook a literature review on the impact of COVID-19 on surgery and perioperative care. A thematic analysis was performed to identify the issues most frequently encountered by the correspondents, as well as the solutions and ideas suggested to address them. Results: BJS received communications for this Commission from leading clinicians and academics across a variety of surgical specialties in every inhabited continent. The responses from all over the world provided insights into multiple facets of surgical practice from a governmental level to individual clinical practice and training. Conclusion: The COVID-19 pandemic has uncovered a variety of problems in healthcare systems, including negative impacts on surgical practice. Global surgical multidisciplinary teams are working collaboratively to address research questions about the future of surgery in the post-COVID-19 era. The COVID-19 pandemic is severely damaging surgical training. The establishment of a multidisciplinary ethics committee should be encouraged at all surgical oncology centres. Innovative leadership and collaboration is vital in the post-COVID-19 era