A Raman anemometer for component-selective velocity measurements of particles in a flow

An anemometer for the measurement of the velocity of particles of different components in a flow, separate and apart from that of the flow itself, is described. As a component-selective mechanism Raman scattering is used. The velocity is measured by relating the autocorrelated scattering signal to the known laser beam profile

Raman anemometry, a method for component-selective velocity measurements of particles in a flow

An anemometer for the measurement of the velocity of particles of different substances in a flow, separate and apart from that of the flow itself, is described. The substances are distinguished by Raman scattering. The velocity is obtained by relating the autocorrelated scattering signal to the known laser beam profile

A Raman spectroscopic study of the interaction between nucleotides and the DNA binding protein gp32 of bacteriophage T4

Raman spectra of the bacteriophage T4 denaturing protein gp32, its complex with the polynucleotides poly(rA), poly(dA), poly(dT), poly(rU), and poly(rC), and with the oligonucleotides (dA)8 and (dA)2, were recorded and interpreted. According to an analysis of the gp32 spectra with the reference intensity profiles of Alix and co-workers [M. Berjot, L. Marx, and A.J.P. Alix (1985) J. Ramanspectrosc., submitted; A.J.P. Alix, M. Berjot, and J. Marx (1985) in Spectroscopy of Biological Molecules, A. J. P. Alix, L. Bernard, and M. Manfait, Eds., pp. 149-154], 1 gp32 contains ≈ 45% helix, ≈ 40% β-sheet, and 15% undefined structure. Aggregation of gp32 at concentrations higher than 40 mg/mL leads to a coordination of the phenolic OH groups of 4-6 tyrosines and of all the sulfhydryl (SH) groups present in the protein with the COO- groups of protein. The latter coordination persists even at concentrations as low as 1 mg/mL. In polynucleotide-protein complexes the nucleotide shields the 4-6 tyrosine residues from coordination by the COO- groups even at high protein concentration. The presence of the nucleotide causes no shielding of the SH groups. With Raman difference spectroscopy it is shown that binding of the protein to a single-stranded nucleotide involves both tyrosine and trytophan residues. A change in the secondary structure of the protein upon binding is observed. In the complex, gp32 contains more -sheet structure than when uncomplexed. A comparison of the spectra of complexed poly(rA) and poly(dA) with the spectra of their solution conformations at 15°C reveals that in both polynucleotides the phosphodiester vibration changes upon complex formation in the same way as upon a transition from a regular to a more disordered conformation. Distortion of the phosphate-sugar-base conformation occurs upon complex formation, so that the spectra of poly(rA) and poly(dA) are more alike in the complex than they are in the free polynucleotides. The decrease in intensity of the Raman bands at 1304 cm-1 in poly(rA), at 1230 cm-1 in poly(rU), and at 1240 and 1378 cm-1 of poly(dT) may be indicative of increased stacking interactions in the complex. No influence of the nucleotide chain length upon the Raman spectrum of gp322 in the complex was detected. Both the nucleotide lines and the protein lines in the spectrum of a complex are identical in poly(dA) and (dA)8

RAMPAC: a program for analysis of complicated Raman spectra

A computer program for the analysis of complicated (e.g. multi-line) Raman spectra is described. The program includes automatic peak search, various procedures for background determination, peak fit and spectrum deconvolution and extensive spectrum handling procedures

Detection of Photoacoustic Transients Originating from Microstructures in Optically Diffuse Media such as Biological Tissue

The generation and detection of broadband photoacoustic (PA) transients may be used for on-axis monitoring or for imaging of optically different structures in the interior of diffuse bodies such as biological tissue. Various piezoelectric sensors are characterized and compared in terms of sensitivity, depth response, and directivity with respect to spherical broadband acoustic pulses. The influence on the sensor output of acoustic interference and refraction of the PA transients at the sample-sensor interface is discussed. Ring detectors are suitable for deep on-axis detection thanks to their strong directional sensitivity, and small disk sensors are most suited for 3-D imaging of microstructures such as the (micro)vascular system. Voltage and charge preamplification schemes are compared in terms of the signal-to-noise ratio (SNR). In all cases, the preamplifier noise turns out to be the limiting factor for the sensitivity. Based on experimental data, for several sensor types and optical wavelengths, the theoretical detectability of PA signals generated by blood-like absorbers in biological tissue is discusse

Age-related changes in local water and protein content of human eye lenses measured by Raman microspectroscopy

The Raman microspectroscopic method was used to determine the local water and protein content in human lenses. In 18 lenses of varying age position-defined water/protein content measurements were carried out along the visual and the equatorial axis.\ud \ud A main characteristic of the human lens is its constant and relatively low protein content. In addition this constant nuclear value is reached within a short distance from the capsular surface. For statistical analysis of age-related changes the data points in individual lenses were piecewise linearized. (1) The mean nuclear water content was calculated from the data points in the inner 80% of the visual axis. (2) The steep drop in water content was linearized using a least-squares linear regression approach. The distance between lenticular surface and the intersection of the regression line with the line representing the nuclear mean was denominated as surface layer width.\ud \ud It proved that: (i) the mean nuclear water content significantly increased with age, (ii) the width of the surface layer was age independent in the anterior and posterior poles of the visual axis, and (iii) in the equatorial axis the surface layer width significantly decreased with age.\ud \ud Seven human lenses with small opaque spots were also investigated. The opaque spots proved to have a normal-for-site water content and some of them were flanked at their capsular side by a zone with a high-for-site water content.\ud \ud The correlation between protein content and refractive index and the observed decrease in nuclear protein content in aging human lenses can be taken as strong evidence that upon aging the refractive index of a major part of the human lens is reduced. The implications of this decrease is discussed with the respect to the problem known as the lens Paradox, i.e. the discrepancy between the theoretically expected age-related loss of far vision due to changes in lens curvature and axial position in the eye and the actually observed loss in near vision upon age

Anthropological Reflections on the Art of the Possible

«In 1956, the Dutch artist Constant Nieuwenhuys started working on a visionary architectural proposal for a future society; he didn’t stop for almost twenty years. Having been a cofounder of the Cobra group of artists in the late forties, he abandoned painting in 1953 to concentrate on the question of ‘construction’. He became a founding member of the Situationist International in 1957 and played a central role in their experiments until his resignation in 1960. New Babylon, as his project would eventually be called, is a situationist city intended as a polemical provocation.Peer Reviewe

Possibilities and limitations of off-resonance polarization sensitive cars of short chain proteins

Polarization sensitive CARS in the absence of resonance enhancement is applied to a short chain protein. The minimum concentration to record polarization sensitive CARS spectra of protein solutions is estimated to be 10 mg/ml. The effects limiting the protein concentration are discussed and regarded from an experimental point of view. Signal strength and line parameters of polarization sensitive CARS spectra of the short chain protein Lysyl-Tryptophyl-Lysine are compared with those of a normal Raman spectrum