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This study aims to provide decision support for future measures to be taken regarding 2 tunnels using high-resolution 3D imaging of the subsurface. This project involves a more comprehensive risk analysis than localized tests, such as geotechnical surveys, and a more precise characterization of the subsoil at the tunnel entrance for approximately 200 meters. To address this issue, a 3D passive seismic tomography was conducted using a network installed on the surface of the study area and another in the tunnels to better analyze the subsurface beneath the tunnels. The 3D shear wave velocity model allowed the identification and delineation of risk zones and the estimation of risk levels based on the analysis of Vs (shear wave velocity) contrasts and their correlation with borehole data.

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Previous research has shown that the polarization ratio technique allows the characterization of the surface mean diameter, D 21 , of droplets forming dilute sprays. However, its application to optically dense sprays has posed significant challenges due to the presence of multiple light scattering. Additionally, errors in measurement can arise from the angular dependence of the signal. In this Letter, we present a novel, to the best of our knowledge, method that addresses these challenges. Our approach combines the use of a telecentric objective with structured laser illumination, to both optimize light detection and suppress the unwanted intensity from multiple scattering. This approach enables the utilization of the polarization ratio technique for measuring the droplet size of challenging atomizing sprays. The method offers a promising solution for accurate and comprehensive spray characterization. It is applied, here, to a hollow-cone water spray running at 30, 50, and 70 bar injection pressure, reaching an optical depth up to three.

Techniques allowing the recovery of large free and membrane-bound polysomes in high yield are reported. Subcellular fractions were prepared from rat liver homogenates as described in the preceding paper. Purified microsomal membranes (obtained from the post-lysosomal supernatant) were adjusted to 50 mM Mg(CH3COO)2 and treated with 2% Triton X-100 and 0.3% sodium deoxycholate in the presence of yeast RNA and cell sap, and polysomes were purified by overnight centrifugation through low-ionic-strength discontinuous sucrose gradients containing 2 mg/ml of cell sap proteins. Polysomes were isolated from the mitochondria/endoplasmic reticulum complex (fraction C) by treatment with 2% Triton X-100 and 0.5% sodium deoxycholate in the presence of 50 mM Tris-HCl, pH 7.6, 0.1 M KCl, 0.15 M NH4Cl and 50 mM Mg(CH3COO)2 and purified through sucrose layers of decreasing ionic strength containing 2 mg/ml of cell sap proteins. Analyses of polysomes in isokinetic sucrose gradients showed that the free polysome fraction and both membrane-bound polysome fractions had 14-15 ribosomes per mRNA at the maximum of absorbance. Experiments from which these methods were derived are described.

Substantial improvements of cellular fractionation in ionic conditions allowing preservation of polysome structure and polysome-membrane interactions are reported. They consist primarily in minimizing the lysosomal content of fractions containing endoplasmic reticulum by isolating a lysosome-rich fraction with little loss (6%) of RNA. Endoplasmic reticulum membranes were recovered in high yield, mainly in association with mitochondria, the remainder being found in the post-lysosomal supernatant. The latter also contained practically all the free polysomes, as judged by metrizamide gradient analyses. The distributions of various constituents (RNA, DNA, protein and marker enzymes) among cell fractions is presented.

The behaviour of rat liver cytoplasmic ribonucleoproteins in metrizamide has been studied to determine whether the iodinated compound would offer any advantage over other centrifugation media for studies of polysome structure and function. 1. Polysomes had a density of 1.295--1.300 g/cm3 in metrizamide gradients which was also the density of glycogen. However, the polysaccharide reached its equilibrium more rapidly than the polysomes. Thus a short centrifugation of a polysome suspension from non-starved rats over a 40% metrizamide cushion was sufficient to eliminate more than 85% of the glycogen with a polysome yield of about 75%. 2. Ribosomal subunits had neighbouring densities (1.23 and 1.20 g/cm3 for large and small EDTA-derived subunits; 1.23 and 1.21 g/cm3 for large and small KCl/puromycin-derived subunits, respectively). Polysomal messenger ribonucleoproteins were heterogeneously distributed (phi = 1.12 to 1.23 g/cm3) and overlapped with subunits in a similar manner as in sucrose gradients. 3. Analysis of a post-mitochondrial supernatant in metrizamide showed a clear separation of free polysomes, rough membranes and the soluble phase.

A sensitive assay, using [14C]lecithin as a substrate, has been developed for the measurement of phospholipase activity in rat peritoneal polymorphonuclear leukocytes. Cell extracts were found to contain a phospholipase D activity and indirect evidence suggested that eosinophils are responsible for the cleavage of lecithin. Intact peritoneal cells were also able to hydrolyze exogenous [14C]lecithin in vitro. When [3H]choline-labeled schistosomula were used as targets in antibody-dependent cytotoxicity experiments, the radioactivity of lecithin decreased more rapidly in a complete cytotoxicity system than in controls, suggesting that hydrolysis of schistosomula phospholipids occurred during the killing process.