Quantum Nature of Plasmon-Enhanced Raman Scattering

We report plasmon-enhanced Raman scattering in graphene coupled to a single plasmonic hotspot measured as a function of laser energy. The enhancement profiles of the G peak show strong enhancement (up to $10^5$) and narrow resonances (30 meV) that are induced by the localized surface plasmon of a gold nanodimer. We observe the evolution of defect-mode scattering in a defect-free graphene lattice in resonance with the plasmon. We propose a quantum theory of plasmon-enhanced Raman scattering, where the plasmon forms an integral part of the excitation process. Quantum interferences between scattering channels explain the experimentally observed resonance profiles, in particular, the marked difference in enhancement factors for incoming and outgoing resonance and the appearance of the defect-type modes.Comment: Keywords: plasmon-enhanced Raman scattering, SERS, graphene, quantum interferences, microscopic theory of Raman scattering. Content: 22 pages including 5 figures + 11 pages supporting informatio

Polarized Plasmonic Enhancement by Au Nanostructures Probed through Raman Scattering of Suspended Graphene

We characterize plasmonic enhancement in a hotspot between two Au nanodisks using Raman scattering of graphene. Single layer graphene is suspended across the dimer cavity and provides an ideal two-dimensional test material for the local near-field distribution. We detect a Raman enhancement of the order of 103 originating from the cavity. Spatially resolved Raman measurements reveal a near-field localization one order of magnitude smaller than the wavelength of the excitation, which can be turned off by rotating the polarization of the excitation. The suspended graphene is under tensile strain. The resulting phonon mode softening allows for a clear identification of the enhanced signal compared to unperturbed graphene

Rapunzel Syndrome: A Rare Presentation with Giant Gastric Ulcer

The Rapunzel syndrome refers to an uncommon and rare form of trichobezoar that extends past the stomach into the small intestines. The Rapunzel syndrome is usually found in young female patients with a history of psychiatric disorders, mainly trichotillomania and trichophagia. We describe a case of Rapunzel syndrome in a 15-year-old girl who presented with abdominal pain, vomiting, and weight loss. We performed a surgical laparotomy and successfully removed a huge trichobezoar extending into the small intestine

Raman Fingerprints of Graphene Produced by Anodic Electrochemical Exfoliation

Electrochemical exfoliation is one of the most promising methods for scalable production of graphene. However, limited understanding of its Raman spectrum as well as lack of measurement standards for graphene strongly limit its industrial applications. In this work we show a systematic study of the Raman spectrum of electrochemically exfoliated graphene, produced using different electrolytes and different types of solvents in varying amounts. We demonstrate that no information on the thickness can be extracted from the shape of the 2D peak as this type of graphene is defective. Furthermore, the number of defects and the uniformity of the samples strongly depend on the experimental conditions, including post-processing. Under specific conditions, formation of short conductive trans-polyacetylene chains has been observed. Our Raman analysis provides guidance for the community on how to get information on defects coming from electrolyte, temperature and other experimental conditions, by making Raman spectroscopy a powerful metrology tool.Comment: This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Nano Letters, American Chemical Society after peer review. To access the final edited and published work, included the SI, see DOI: 10.1021/acs.nanolett.0c0033

All-sky Medium Energy Gamma-ray Observatory: Exploring the Extreme Multimessenger Universe

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in the 200 keV to 10 GeV energy range with a wide field of view, good spectral resolution, and polarization sensitivity. Therefore, AMEGO is key in the study of multimessenger astrophysical objects that have unique signatures in the gamma-ray regime, such as neutron star mergers, supernovae, and flaring active galactic nuclei. The order-of-magnitude improvement compared to previous MeV missions also enables discoveries of a wide range of phenomena whose energy output peaks in the relatively unexplored medium-energy gamma-ray band

Συγκριτικές παρατηρήσεις μεταξύ των ενεργών ρηγμάτων της ορεινής Κορινθίας και της χερσονήσου της Περαχώρας

Στην εργασία μελετήθηκε η ευρύτερη περιοχή του Ανατολικού Κορινθιακού κόλπου ως προς τη νεοτεκτονική εξέλιξή της. Η πρώτη περιοχή που μελετηθηκε είναι η μεταλπική λεκάνη του Αγ. Ιωάννη η οποία ανήκει στο τεκτονικό κέρας του Αραχναίου. Η δεύτερη περιοχή περιλαμβάνει τα σεισμικά ρήγματα των Πισσίων και του Σχίνου τα οποία ανήκουν στην χερσόνησο της Περαχώρας.In this paper the wider area of the Eastern Corinthian Gulf in terms of its neotectonic evolution was studied. The first neotectonic area that was studied is the metal basin of Ag. Ioannis which belongs to the tectonic horn of Arachnaeus. The second area includes the faults of Pissia and Schinos which belong to the Perachora peninsula

A case-control study of the periodontal condition in gastric cancer patients

Aim: The present study was carried out to examine the possible differences regarding the periodontal condition between individuals with a gastric cancer history diagnosed by histological examination and healthy individuals.Methods: Sixty-five patients suffered from non-cardia adenocarcinoma diagnosed by histological examination and 60 matched healthy controls were interviewed and clinically examined. Data analysis was performed by χ2 test and logistic regression model to estimate possible correlations regarding the periodontal condition of the mentioned individuals after assessment. The assessment included the following clinical parameters: probing pocket depth, clinical attachment loss, gingival index, and bleeding on probing.Results: Smoking [odds ratio (OR) = 4.448, 95% confidence interval (CI) = 1.818-10.880], gingival inflammation (OR = 2.019, 95% CI = 0.933-11.579) and clinical attachment loss (OR = 5.167, 95% CI = 2.122-12.584), were statistically significant differences between the cases and the controls, after adjustment for smoking and socioeconomic status.Conclusion: Smoking, gingival inflammation, and clinical attachment loss were statistically significantly different between patients who had gastric cancer and healthy individuals