Cryogenic Ion Fluorescence Spectroscopy: FRET in Rhodamine Homodimers and Heterodimers.

The internal electronic communication between two or more light-absorbers is fundamental for energy-transport processes, a field of large current interest. Here the intrinsic photophysics of homo- and heterodimers of rhodamine cations were studied where just two methylene units bridge the dyes. Gas-phase experiments were done on frozen molecular ions at cryogenic temperatures using the newly built LUNA2 mass spectroscopy setup in Aarhus. Both absorption (from fluorescence excitation) and dispersed-fluorescence spectra were measured. In the gas phase, there is no dielectric screening from solvent molecules, and the effect of charges on transition energies is maximum. Indeed, bands are redshifted compared to those of monomer dyes due to the electric field that each dye senses from the other in a dimer. Importantly, also, as two chemically identical dyes in a homodimer do not experience the same field along the long axis, each dye has separate absorption. At low temperatures, it is therefore possible to selectively excite one dye. Fluorescence is dominantly from the dye with the lowest transition energy no matter which dye is photoexcited. Hence this work unequivocally demonstrates Förster Resonance Energy Transfer even in homodimers where one dye acts as donor and the other as acceptor.

Revealing nanoscale sorption mechanisms of gases in a highly porous silica aerogel.

Geological formations provide a promising environment for the long-term and short-term storage of gases, including carbon dioxide, hydrogen and hydro-carbons, controlled by the rock-specific small-scale pore structure. This study investigates the nanoscale structure and gas uptake in a highly porous silica aerogel (a synthetic proxy for natural rocks) using transmission electron microscopy, X-ray diffraction, and small-angle and ultra-small-angle neutron scattering with a tracer of deuterated methane (CD4) at pressures up to 1000 bar. The results show that the adsorption of CD4 in the porous silica matrix is scale dependent. The pore space of the silica aerogel is fully accessible to the invading gas, which quickly equilibrates with the external pressure and shows no condensation on the sub-nanometre scale. In the 2.5-50 nm pore size region a classical two-phase adsorption behaviour is observed. The structure of the aerogel returns to its original state after the CD4 pressure has been released.

Gamma-delta T-cell lymphoma with CNS involvement presenting with proptosis: a case study workup, treatment and prognosis.

INTRODUCTION: Ocular adnexal lymphomas are rare and T cell variants are a minor subset of these lymphomas. We aim to describe a case report which underlines the diagnostic and treatment challenge of this rare pathology. CASE: A 34-year-old gentleman has been shown to have exophthalmos and dysfunction of cranial nerve V andVII unilaterally. Imaging including CT and MRI brain and orbits do not show a CNS component to the disease. It was later identified as an ocular adnexal lymphoma with a central nervous system (CNS) component diagnosed via lumbar puncture. DISCUSSION: We highlight the importance of excluding ocular adnexal lymphoma and difficulty of management of the disease where it presents as a masquerade syndrome for orbital cellulitis.

Recurrent orbital myositis with radiological feature mimicking thyroid eye disease in a patient with Crohn's disease.

Orbital myositis is an extremely rare extra-intestinal manifestation of Crohn's disease. Herein we describe a patient with self-limiting episodes of episcleritis and uveitis prior to the diagnosis of Crohn's disease, and subsequent development of recurrent orbital myositis with radiological features mimicking thyroid eye disease.

Pott's puffy tumor in a premature neonate: the new youngest case reported in the post-antibiotic era.

An extreme premature infant born at 25 weeks post menstrual age (PMA) presented at PMA of 32 weeks with non-multiresistant methicillin resistant Staphylococcus aureus (MRSA) Pott's puffy tumor (PPT) involving both orbital and intracranial extension is described here. This is the youngest case of PPT ever reported in the antibiotic era.

Reactivation of Graves' orbitopathy after rehabilitative orbital decompression.

OBJECTIVE: To present and discuss three cases of apparent reactivation of Graves' orbitopathy (GO) after orbital decompression and to evaluate the incidence of this phenomenon. DESIGN: Observational case series and retrospective follow-up study. PARTICIPANTS: A few weeks after surgery 2 patients with GO (patients 1 and 2), treated at our institution with rehabilitative bony orbital decompression during the static phase of the disease showed clinical and radiologic evidence of reactivated orbitopathy. After this observation, a sample of 249 patients who had consecutively undergone the same treatment for the same reason before the second of the 2 observed patients was selected for this study. METHODS: The records of the selected patients were retrospectively reviewed searching for cases presenting with clinical and radiologic evidence of GO reactivated as a consequence of any type of bony orbital decompression. Patients treated with perioperative systemic glucocorticoids or who had concurrent periorbital diseases, injuries, or surgeries, or who had immunocompromised conditions or a follow-up of < or =2 months, were excluded. MAIN OUTCOME MEASURES: Incidence of reactivation. Clinical history, clinical and radiologic characteristics, treatment modalities, and time course of the reactivation in patients presenting with this phenomenon. RESULTS: Decompression surgery took place between 1994 and 2000. Eleven patients were excluded for having been treated with perioperative glucocorticoids. Only 1 patient (patient 3) presented with reactivation. The incidence of the phenomenon that we regard as reactivation of GO after rehabilitative bony orbital decompression was therefore 1.3% (3/239). In all 3 patients, the reactivation took place a few weeks after surgery, after an early normal convalescence period and could be controlled with systemic immunosuppression or orbital radiotherapy. None of the patients we report developed further episodes of reactivation during the follow-up period (mean, 7.5 years). CONCLUSIONS: Based on its clinical characteristics, we suggest naming our observation delayed decompression-related reactivation and we propose using its acronym DDRR when referring to it. Although DDRR appears to be a rare event, it is important for physicians and patients to be aware of its possible occurrence with rehabilitative decompression surgery.