Partial correction estimation of adaptive optics systems for large fields of view

A novel method for the simulation of atmospheric turbulence-degraded wavefronts is shown. The computer generated wavefronts contain all the statistical and spatial properties predicted for Kolmogorov-type turbulence. The technique enables the generation of wavefronts from two separated point sources while maintaining the correct correlation. The techniques was used to check the effects of anisoplanitism on the performance of wavefront compensation by adaptive optics using the modal correction. The dependence on the order of correction was also estimated. It is shown that for strong turbulence, for extended sources, there is no benefit of correction beyond the third order (tilt).     

Transmission et indice de refraction des photoresines negatives KMR-747 dans l'infrarouge entre 2 et 10 μm

This paper deals with the infrared transmission and dispersion of negative photoresists KMR 747, available from kodak stock. We have computed the absorption coefficient curve and determined the refractive index of the material by an accurate interferometric measuring method (channeled spectrum) between 2 and 10 μm in wavelenght. The study of these optical constants permit one to precise the optimum utilization of the photoresists as phase profiles material for the infrared.     

Direct measurement of the effective charge in nonpolar suspensions by optical tracking of single particles

The authors develop an ultrasensitive method for the measurement of the charge carried by a colloidal particle in a nonpolar suspension. The technique uses the phenomenon of the resonance of a particle held in an optical tweezer trap and driven by a sinusoidal electric field. The trapped particle forms a strongly damped harmonic oscillator whose fluctuations are a function of gamma, the ratio of the root-mean-square average of the electric and thermal forces on the particle. At low applied fields (gamma<1) the particle is confined to the optical axis, while at high fields (gamma>1) the probability distribution of the particle is double peaked. The periodically modulated thermal fluctuations are measured with nanometer sensitivity using an interferometric position detector. Charges, as low as a few elementary charges, can be measured with an uncertainty of about 0.25 e. This is significantly better than previous techniques and opens up new possibilities for the study of nonpolar suspensions.     

Iodo-carbocyclization of electron-deficient alkenes: synthesis of oxindoles and spirooxindoles

Cyclisative carbo-iodination of N-alkyl-N-arylacrylamide derivatives (3) in the presence of PhI(OAc)(2)/I(2) afforded functionalized 3-(iodomethyl)-3-substituted-indolin-2-ones (4) in good to excellent yields. With a suitably functionalized linear amide, spirooxindole 8 was prepared in a one-pot fashion via a sequence of iodo-arylation followed by an in situ base-promoted intramolecular S(N)2 reaction.     

Importance of accurate spectral simulations for the analysis of terahertz spectra: citric acid anhydrate and monohydrate

The terahertz (THz) spectra of crystalline solids are typically uniquely sensitive to the molecular packing configurations, allowing for the detection of polymorphs and hydrates by THz spectroscopic techniques. It is possible, however, that coincident absorptions may be observed between related crystal forms, in which case careful assessment of the lattice vibrations of each system must be performed. Presented here is a THz spectroscopic investigation of citric acid in its anhydrous and monohydrate phases. Remarkably similar features were observed in the THz spectra of both systems, requiring the accurate calculation of the low-frequency vibrational modes by solid-state density functional theory to determine the origins of these spectral features. The results of the simulations demonstrate the necessity of reliable and rigorous methods for THz vibrational modes to ensure the proper evaluation of the THz spectra of molecular solids.     

Bisulfite-free analysis of 5MeC-binding proteins and locus-specific methylation density using a microparticle-based flow cytometry assay

DNA methylation analysis is emerging as a new technique with potential capabilities for early cancer detection. However, current state-of-the-art techniques are not easily translatable into routine clinical methods. Herein we describe a bead-based flow cytometry assay which combines DNA hybridization to microparticles with 5MeC-specific proteins/antibodies. These assays can be used to study the binding properties of current and emerging 5MeC-binding proteins and may also have potential in the measurement of 5MeC density in clinical samples for cancer detection.     

Sensitive determination of glyoxal, methylglyoxal and hydroxyacetaldehyde in environmental water samples by using dansylacetamidooxyamine derivatization and liquid chromatography/fluorescence

In this study we improved the dansylacetamidooxyamine (DNSAOA)-LC-fluorescence method for the determination of aqueous-phase glyoxal (GL), methylglyoxal (MG) and hydroxyacetaldehyde (HA). As derivatization of dicarbonyls can potentially lead to complex mixtures, a thorough study of the reaction patterns of GL and MG with DNSAOA was carried out. Derivatization of GL and MG was shown to follow the kinetics of successive reactions, yielding predominantly doubly derivatized compounds. We verified that the bis-DNSAOA structure of these adducts exerted only minor influence on their fluorescence properties. Contrary to observations made with formaldehyde, derivatization of GL, MG and, to a lesser extent of HA, was shown to be faster in acidic (H(2)SO(4)) medium with a maximum of efficiency for acid concentrations of ca. 2.5 mM. Concomitant separation of GL, MG, HA and of single carbonyls was achieved within 20 min by using C(18) chromatography and a gradient of CH(3)CN in water. Detection limits of 0.27, 0.17 and 0.12 nM were determined for GL, MG and HA, respectively. Consequently, low sample volumes are sufficient and, unlike numerous published methods, neither preconcentration nor large injection volumes are necessary to monitor trace-level samples. The method shows relative measurement uncertainties better than ±15% at the 95% level of confidence and good dynamic ranges (R(2)>0.99) from 0.01 to 1.5 μM for all carbonyls. GL, MG and HA were identified for the first time in polar snow samples, but also in saline frost flowers for which unexpected levels of 0.1-0.6 μM were measured. Concentrations in the 0.02-2.3 μM range were also measured in cloud water. In most samples, a predominance of HA over GL and MG was observed.