Ophthalmological prognosis via fuzzy subsets

This paper examines the possibility of handling treatment effects as a fuzzy relational problem with particular reference to ophthalmology. An ophthalmological evaluation is considered to consist of two major stages. Firstly, an explanation of a patient's eye-health state in terms of known disease labels is formulated through diagnosis. Secondly, the effectiveness of a therapeutic strategy designed to restore a patient's normal eye-health, is then predicted via prognosis. The paper considers the latter aspect in the sense of assessing the effects of medical intervention by comparing pre- and post-therapeutic fuzzy subsets.     

A simple QuEChERS-like extraction approach for molecular chemical characterization of organic aerosols: application to nitrated and oxygenated PAH derivatives (NPAH and OPAH) quantified by GC–NICIMS

An extraction procedure based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) approach has been developed and used for analysis of particle-bound nitrated and oxygenated PAH derivatives (NPAH and OPAH, respectively). Several analytical conditions, for example GC injection temperature and MS detection settings, were optimized. This analytical procedure enabled simultaneous GC–NICIMS quantification of 32 NPAH and 32 OPAH (or other oxygenated compounds), including typical components of secondary organic aerosol (SOA) formed by photooxidation of PAH (e.g. 2-formyl-trans-cinnamaldehyde and 6H-dibenzo[b,d]pyran-6-one). The QuEChERS-like approach was optimized, including the nature of the extraction solvent, the sorbent used for clean-up, and extraction time. The final extraction procedure was based on brief mechanical agitation (vortex mixing for 1.5 min), with 7 mL acetonitrile as solvent. Because dispersive solid-phase extraction (d-SPE) did not provide satisfactory results, SPE using SiO₂ was selected for sample purification. Identical results were obtained when the QuEChERS-like and traditional pressurised solvent extraction (PLE) procedures were compared for analysis of fortified ambient air particle samples. The procedure was validated by analysis of two aerosol standard reference materials (NIST SRM 1649b (urban dust) and SRM 2787 (fine particulate matter, <10 μm)). For numerous NPAH and OPAH, this is the first report of their quantification in both SRMs. Compared with other extraction methods, including PLE, the QuEChERS-like procedure resulted in increased productivity and reduced extraction cost. This paper shows that QuEChERS-like extraction procedures can be suitably adapted for molecular chemical characterization of aerosol samples and could be extended to other categories of compound.

Two Photon‐Induced Electron Injection From a Nanotrigger in Native Endothelial NO‐Synthase

We have recently designed a nanotrigger (NT), a photoactive molecule addressing the NADPH sites of proteins. This nanotrigger has a 10³ times larger two‐photon cross‐section compared to the ubiquitous NADPH cofactor. In this work, we tested whether two‐photon excitation of the bound NT to NADPH sites may be used to initiate enzymatic catalysis by appropriate electron injection. To establish proof of principle, we monitored the ultrafast absorption of NT bound to the fully active endothelial NO‐Synthase (eNOS) following excitation by one and two‐photons at 405 and 810 nm, respectively. Electron injection from NT* to FAD in eNOS initiated the catalytic cycle in 15±3 ps at both exciting wavelengths. The data proved for the first time that electron transfer can be promoted by two‐photon excitation. We also show that the nanotrigger decays faster in homogeneous solvents than in the NADPH site of proteins, suggesting that hindered environments modified the natural decay of NT. The nanotrigger provides a convenient way of synchronizing an ensemble of proteins in solution with a femtosecond laser pulse. The ability of NT to initiate NOS catalysis by two‐photon excitation may be exploited for controlled and localized release of free NO in cells with enhanced spatial and temporal resolution.     

Electron heating in a submicron-size n GaAs wire

We have studied electron heating in a submicron-size GaAs wire from 4.2 K to 50 K. We find that the energy relaxation rate for the electrons is of the form τ_E⁻¹ = α + βT_eⁿ where α, β are constants and T_e is the electron temperature. We associate the temperature-independent term with a quasi-elastic surface scattering process in which an electron losses 1% of its energy at each collision. The temperature dependent term may be due to electron-phonon scattering. It is possible to fit the data to 2 < n < 3.