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The ability to routinely detect fluorescent nucleobase analogues at the single-molecule level would create a wealth of opportunities to study nucleic acids. We report the multiphoton-induced fluorescence and single-molecule detection of a dimethylamine-substituted extended-6-aza-uridine (DMAthaU). We show that DMAthaU can exist in a highly fluorescent form, emitting strongly in the visible region (470-560 nm). Using pulse-shaped broadband Ti:sapphire laser excitation, DMAthaU undergoes two-photon (2P) absorption at low excitation powers, switching to three-photon (3P) absorption at high incident intensity. The assignment of a 3P process is supported by cubic response calculations. Under both 2P and 3P excitation, the single-molecule brightness was over an order of magnitude higher than reported previously for any fluorescent base analogue, which facilitated the first single-molecule detection of an emissive nucleoside with multiphoton excitation.

My debut novel, The Peach Seed, was released by Henry Holt on August 1, 2023. To prepare for this moment, I geared up to use my creator skills to promote [...]

The effects of excitation wavelength on the optical properties (emission spectrum and quantum yield) of a luminescent solar concentrator (LSC) containing a fluorescent organic dye (Lumogen F Rot 305) are studied. Excitation at wavelengths on the long-wavelength edge of the absorption spectrum of the dye results in redshifted emission, but the quantum yield remains constant at 100%. The origin of this effect and its consequences are discussed. The extent of the long-wavelength tail of the absorption spectrum of the dye is determined and the importance in reabsorption losses is shown. The optical efficiencies and photon transport probabilities of LSCs containing either an organic dye or a rare-earth lanthanide complex are compared using ray-tracing simulations and experiment. The optical efficiency is shown to depend strongly on the Stokes shift of the fluorophore. The lanthanide complex, which has a very large Stokes shift, exhibits a higher optical efficiency than the dye (64% cf. 50%), despite its lower quantum yield (86% cf. 100%). [c] 2010 Optical Society of America OCIS codes: 260.2510, 300.6280, 250.5460, 350.6050.

The decontamination of a range of 'in-use' stainless steel surgical instruments by conventional hospital reprocessing techniques was studied, using scanning electron microscopic (SEM) and energy dispersive X-ray spectroscopic (EDX) analyses, with results obtained when an Ar:[O.sub.2] RF gas-plasma treatment step was added to the cleaning cycle. In some cases, protein contaminants were still retained on instruments subjected to conventional cleaning and sterilization after seven cleaning cycles. No retention of contamination was evident on the surfaces of instruments that were subjected to gas-plasma cleaning. The efficacy of the plasma decontamination is significantly improved by hydration of the tissue residues immediately before exposure to the plasma. The reasons for this are not known, but it is suggested that the production of excited OH radicals and H atoms within the tissue matrix may play some part. Deposition of fluorescently labeled protein from physiological saline solution shows that protein is incorporated into salt crystals formed on stainless steel surfaces. This protein is resistant to plasma etching, but it is shown that water treatment results in improved cleaning. A combination of effects including physical 'cracking' of the salt crystals under vacuum and dissolution of the inorganic matrix, which could possibly be accelerated by dipolar heating of the aqueous phase, may be responsible. Index Terms--Creutzfeldt-Jakob disease (CJD), decontamination, radio frequency (RF) gas-plasma, surgical instruments.

The fluorescence decay characteristics of 2-aminopurine (2AP) and 2-aminopurine riboside (2APr) were investigated as a function of excitation wavelength in aqueous and ethanolic solutions. Global analysis of the decay data showed that 2AP existed as two emitting species, whereas 2APr existed as a single species.

Abstract Background An assumption of clinical competency is no longer acceptable or feasible in routine clinical practice. We sought to determine the feasibility, practicability and efficacy of undertaking a formal assessment of clinical competency for all postgraduate medical trainees in a large NHS foundation trust. Methods FY1 doctors were asked to complete a questionnaire to determine prior experience and self reported confidence in performing the GMC core competencies. From this a consensus panel of key partners considered and developed an 8 station Objective Structured Clinical Examination (OSCE) circuit to assess clinical competencies in all training grade medical staff... The OSCE was then administered to all training grade doctors as part of their NHS trust induction process. Results 106 (87.6% of all trainees) participated in the assessment during the first 14 days of appointment. Candidates achieved high median raw percentage scores for the majority of stations however analysis of pre defined critical errors and omissions identified important areas for concern. Performance of newly qualified FY1 doctor was significantly better than other grades for the arterial blood gas estimation and nasogastric tube insertion stations. Discussion Delivering a formal classroom assessment of clinical competencies to all trainees as part of the induction process was both feasible and useful. The assessment identified areas of concern for future training and also served to reassure as to the proficiency of trainees in undertaking the majority of core competencies.

The conformational behaviour of tyramine and phenethylamine as well as the number, geometry and electronic structure of stable conformers are described. The conformer dependence of the TDM orientation and the influence of the OH group on these properties are examined.

Investigated here are the aggregation properties of CuPcS4 in aqueous salt solutions using UV-vis spectroscopy and equilibrium statically mechanics. It is shown that the monomer-dimer model (MD) is unable to describe the qualitative behavior of the molar absorption coefficients at CuPcS4 concentrations above 10 (super -4) M and alternative model that takes into account the formation of trimer and all higher aggregates has to be put forward.