Enhancement of computed tomography liver contrast using iomeprol-containing liposomes and detection of small liver tumors in rats

RATIONALE AND OBJECTIVES: We evaluated iomeprol-containing liposomes (Lipiom), a new contrast medium for computed tomography (CT) liver scanning, in an animal model of chemically induced hepatocellular carcinomas and other liver tumors in rats. METHODS: Liver tumors were induced by administration of carcinogens to rats, either 0.55% (w/w) 1'-hydroxysafrole in the diet or induction by 3'-methyl-4-diethylaminoazobenzene followed by promotion with carbon tetrachloride. CT scanning was performed 1-3 hr after intravenous injection of iomeprol-containing liposomes. RESULTS: After injection of iomeprol-containing liposomes at a dose of 70 mg of liposome-entrapped iodine per kilogram of body weight, the normal liver parenchyma showed a contrast enhancement, in Hounsfield units, of more than 60% over the control value before bolus. Liver tumors with no or few Kupffer cells were not enhanced and appeared as dark areas within the normal parenchyma. Tumors and pretumoral lesions devoid of Kupffer cells, as small as 3 mm in diameter, could be distinguished using this non-invasive method. CONCLUSION: CT liver scanning after injection of iomeprol-containing liposomes appears to be promising method for detecting liver tumors and focal liver lesions.     

Photoluminescence excitation spectroscopy of InAs0.67P0.33/InP strained single quantum wells

The optical emission characteristics of biaxially compressed InAs _x P_{1− x} /InP strained single quantum well (QW) structures, with nominal compositionx=0.67, have been investigated using photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies. The highly strained QWs exhibit intense and narrow PL in the 0.9–1.5 μm wavelength range, similar to the lattice-matched InGaAs(P)/InP system. The 20 K PLE spectra exhibit well-resolved features attributed ton=1 heavy hole (E1H1) and light hole (E1L1) transitions in the 1.0–1.5 μm wavelength range. In addition, features attributed to transitions betweenn=2 electrons and heavy holes (E2H2), and betweenn=1 electrons and unconfined holes (E1Hf), were observed. The energy splitting between the heavy-hole and light-hole bands was found to be a sensitive measure of the band offsets in the system. The best prediction of this splitting was obtained for a valence band offset of δE _V ∼0.25δE _G . This value of band offset was in agreement with the energy position of the E1Hf transition. The observed transition energies were also compared with the results of a finite square well model, taking into account the effects of strain, and the results offer further support for the band offset assignment. This study indicates that the InAsP system may be advantageous for application in strained-layer optoelectronic devices operating in the 1.3–1.6 μm wavelength range.     

Experimentelle Bestimmung der spezifischen elektrischen Leitfähigkeit hoch CaF2-haltiger Schlacken

In a comprehensive literature study applied measurement methods for determination of the specific electrical conductivity of slags were compared. Based on these conclusions, a Tammann furnace was modified to a conductivity measuring system with four electrodes. A qualitative and quantitative comparison of results from literature with the practical results of multiple investigations of CaF₂ slags with a purity of 99.5% was carried out.     

pH and salt responsive poly(N,N-dimethylaminoethyl methacrylate) cylindrical brushes and their quaternized derivatives

We present the synthesis and characterization of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) cylindrical brushes, their pH responsiveness, and the corresponding quaternized analog, poly{[2-(methacryloyloxy)ethyl] trimethylammonium iodide} (PMETAI) brushes. PDMAEMA brushes were prepared by atom transfer radical polymerization (ATRP) using the grafting-from strategy. Initiating efficiencies of the ATRP processes were determined by cleaving the side-chains and gel permeation chromatography (GPC) analysis. Due to the slow initiation and steric hindrance, the initiating efficiency is only around 50%. The PDMAEMA brushes show worm-like structures and pH responsiveness, as proven by dynamic light scattering (DLS), atomic force microscopy (AFM), and cryogenic transmission electron microscopy (cryo-TEM) measurements. Strong cationic polyelectrolyte PMETAI brushes were produced by quaternization of the PDMAEMA brushes. AFM and cryo-TEM images showed similar worm-like morphologies for the PMETAI brushes. The PMETAI brushes collapsed in solution with high concentration of monovalent salt, as proven by DLS and AFM results.     

Durability of polymeric glazing materials for solar applications

The economic viability of solar collector systems for domestic hot water (DHW) generation is strongly linked to the cost of such systems. Installation and hardware costs must be reduced by 50% to allow significant market penetration. An attractive approach to cost reduction is to replace glass and metal parts with less expensive, lighter weight polymeric components. Weight reduction decreases the cost of shipping, handling, and installation. The use of polymeric materials also allows the benefits and cost savings associated with well established manufacturing processes, along with savings associated with improved fastening, reduced part count, and overall assembly refinements. A key challenge is to maintain adequate system performance and assure requisite durability for extended lifetimes. Results of preliminary and ongoing screening tests for a large number of candidate polymeric glazing materials are presented. Based on these results, two specific glazings with moderate and poor weathering stability are selected to demonstrate how a service lifetime methodology can be applied to accurately predict the optical performance of these materials during in-service use. A summary is given for data obtained by outdoor exposure and indoor testing of polyvinyl chloride (PVC) and high temperature modified polycarbonate copolymer (coPC) materials, and an initial risk analysis is given for the two materials. Screening tests and analyses for service lifetime prediction are discussed. A methodology that provides a way to derive correlations between degradation experienced by materials exposed to controlled accelerated laboratory exposure conditions and materials exposed to in-service conditions is given, and a validation is presented for the methodology based upon durability test results for PVC and coPC.     

Mapping surface temperature in large lakes with MODIS data

Satellite sensor MODIS on two platforms can produce Sea Surface Temperature over certain regions about three to four times per day. Our objective was to test if the MODIS SST product can be applied for lakes whose surface areas are large enough to be observed at the MODIS spatial resolution and to compare the satellite-derived lake surface temperatures with in situ measurements. Surface temperatures for Lakes Vänern and Vättern in Sweden, two of the largest European lakes, are extracted from the MODIS/Terra images for period 2001-2003. The results are analyzed on different quality levels, as all MODIS L2 products are equipped with an additional quality flag. We present temperature development over 2001-2003, and show the capability of the MODIS SST product to couple the known thermodynamical features in the lakes under study, where temperature varies greatly with space and time. These results can complement lake monitoring programs anywhere.