The generation of surface plasmon polaritons (SPP's) at isolated nanoholes in 100 nm thick Au films is studied using near-field scanning optical microscopy (NSOM). Finitedifference time-domain calculations, some explicitly including a model of the NSOM tip, are used to interpret the results. We find the holes act as point-like sources of SPP's and demonstrate that the interference between the SPP and a directly transmitted wave allows for the determination of the wavelength, phase, and decay length of the SPP. The nearfield intensity patterns can be manipulated by varying the angle and polarization of the incident beam.

This work is a study of the formation mechanisms of interface traps (Nit) in metal-oxide-semiconductor devices. The time-dependence of the Nit formation has been measured as a function of oxide thickness following a short radiation pulse. The Nit formation time is found to increase as t2.6ox when the gate bias is negative during irradiation and positive afterward. This result is in excellent agreement with predictions of a hydrogen transport model where drift of hydrogen ions (H+) is the rate-limiting step. When the gate bias during irradiation is positive, interpretation of the correlation between data and model suggests that the hydrogen ions are preferentially created near the Si-SiO2 interface. Finally, the Nit formation time is found to decrease with increasing oxide field as E−1.73ox. This result is compatible with the hydrogen transport model if the average displacement per hop is assumed to be proportional to Em.

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Nitric oxide (NO) binds to the myoglobin (Mb) cavity mutant, H93G, forming either a five- or six-coordinate Fe-NO complex. The H93G mutation eliminates the covalent attachment between the protein and the proximal ligand, allowing NO to bind H93G possibly from the proximal side of the heme rather than the typical diatomic binding pocket on the distal side. The question of whether NO binds on the distal or proximal side was addressed by FTIR spectroscopy of the N-O vibrational frequency nuN(-O) for a set of Mb mutants that perturb the electrostatic environment of the heme pocket. Vibrational spectra of five- and six-coordinate MbNO complexes indicate that nu(N-O) shifts (by as much as 26 cm(-1)) to higher energies for the distal mutants H64V and H64V/H93G relative to the energies of wild-type and H93G MbNO, while nu(N-O) is not affected by the proximal side mutation S92A/H93G. This result suggests that NO binds on the distal side of heme in the five- and six-coordinate MbNO complexes of H93G. Additionally, values of the Fe-NO vibrational frequency nu(Fe-NO) as measured by resonance Raman spectroscopy are reported for the distal and proximal double mutants of H93G. These results suggest that nu(Fe-NO) is not very sensitive to mutations that perturb the electrostatic environment of the heme pocket, leading to the observation that nu(N-O) and nu(Fe-NO) are not quantitatively correlated for the MbNO complexes presented here. Furthermore, nu(N-O) and nu(Fe-NO) do not correlate well with equilibrium constants for imidazole binding to the five-coordinate MbNO complexes of the H93G double mutants. The data presented here do not appear to support the presence of pi-back-bonding or an inverse trans effect of NO binding in Mb mutants that alter the electrostatic environment of the heme pocket.

Since their initial discovery in the early 1990s, microRNAs have now become the focus of a multitude of lines of investigation ranging from basic biology to translational applications in the clinic. Previously believed to be of no biological relevance, microRNAs regulate processes fundamental to human health and disease. In diseases of the lung, microRNAs have been implicated in developmental programming, as drivers of disease, potential therapeutic targets, and clinical biomarkers; however, several obstacles must be overcome for us to fully realize their potential therapeutic use. Here, we provide for the clinician an overview of microRNA biology in selected diseases of the lung with a focus on their potential clinical application.

Resonance Raman spectroscopy has been used to observe changes in the iron-ligand stretching frequency in photoproduct spectra of the proximal cavity mutant of myoglobin H93G. The measurements compare the deoxy ferrous state of the heme iron in H93G(L), where L is an exogenous imidazole ligand bound in the proximal cavity, to the photolyzed intermediate of H93G(L)*CO at 8 ns. There are significant differences in the frequencies of the iron-ligand axial out-of-plane mode m(Fe-L) in the photoproduct spectra depending on the nature of L for a series of methylsubstituted imidazoles. Further comparison was made with the proximal cavity mutant of myoglobin in the absence of exogenous ligand (H93G) and the photoproduct of the carbonmonoxy adduct of H93G (H93G-*CO). For this case, it has been shown that H 2 O is the axial (fifth) ligand to the heme iron in the deoxy form of H93G. The photoproduct of H93G-*CO is consistent with a transiently bound ligand proposed to be a histidine. The data presented here further substantiate the conclusion that a conformationally driven ligand switch exists in photolyzed H93G-*CO. The results suggest that ligand conformational changes in response to dynamic motions of the globin on the nanosecond and longer time scales are a general feature of the H93G proximal cavity mutant.Keywords: resonance Raman, heme, myoglobin, hemoglobin, ligand switch.Protein structural relaxation following heme photolysis has been studied in globins as a means to obtain information on structural intermediates following diatomic ligand photolysis. In hemoglobin (Hb), time-resolved spectroscopic studies have provided information on the time scale for transition from the six-coordinate R state to the fivecoordinate T-state [1][2][3]. The proximal cavity mutant of Hb has recently demonstrated the key role of the proximal histidine in the cooperativity of quaternary structure change in response to ligand binding [4]. Strain in the covalent bond to the heme iron of Hb can be monitored by following the shift in frequency of the iron-histidine axial mode, m(FeHis), by time-resolved resonance Raman spectroscopy [5]. In myoglobin (Mb), these studies have indicated a much smaller change in structure [6]: the observed frequency shift of the iron-histidine band is c. 1.6 cm )1 on the 8 ns time scale compared to 12 cm )1 in Hb. Nonetheless, this shift in the m(Fe-His) Raman band is significant because shifts in absorption bands (the time-dependent Soret band shift and band III shift) have been attributed to iron out-of-plane displacement that should also be coupled to m(Fe-His) [7][8][9][10]. A structural interpretation of these observable phenomena helps to bridge the gap between the extensive X-ray crystallography studies and the thermodynamic and kinetic data available for Mb [7,[11][12][13][14][15][16][17][18][19][20].Histidine-ligated heme enzymes have a surprisingly large range of functions. In peroxidase, a charge relay due to hydrogen bonding of the imidazole ring of histidine permits the formation of high valent iro...