Evaluation of gadoxetate disodium as a contrast agent for mouse liver imaging: comparison with gadobenate dimeglumine

We investigated the characteristics of gadoxetate disodium (Gd-EOB-DTPA) as a contrast agent for magnetic resonance imaging of the mouse liver. Mice were imaged sequentially under isoflurane anesthesia using a T1-weighted, three-dimensional fast low-angle shot (3D FLASH) sequence after an intravenous injection of Gd-EOB-DTPA or gadobenate dimeglumine (Gd-BOPTA), and the time course of the contrast effect was examined. The time course of the contrast effect of Gd-EOB-DTPA was also assessed after intravenous injection under pentobarbital anesthesia and after subcutaneous injection while awake or under isoflurane or pentobarbital anesthesia. Moreover, different doses of Gd-EOB-DTPA or Gd-BOPTA were injected subcutaneously into conscious mice, and the clarity of the liver border was evaluated visually. Intravenous injection under isoflurane anesthesia caused rapid contrast enhancement in the liver with both Gd-EOB-DTPA and Gd-BOPTA, and the contrast effect was 41% stronger with Gd-EOB-DTPA. Subcutaneous injection of Gd-EOB-DTPA caused delayed but favorable contrast enhancement in the liver. Washout of Gd-EOB-DTPA was faster in mice injected while awake than in those injected under anesthesia. After intravenous injection, washout was faster under pentobarbital anesthesia than under isoflurane anesthesia. The peak liver contrast was 11% and 18% stronger under pentobarbital anesthesia than under isoflurane anesthesia, after intravenous and subcutaneous injections, respectively. Subcutaneous injection of Gd-EOB-DTPA or Gd-BOPTA caused dose-dependent contrast effects in the liver. At a given dose, the contrast effect tended to be stronger and liver demarcation tended to be clearer with Gd-EOB-DTPA than with Gd-BOPTA. In conclusion, intravenous or subcutaneous injection of Gd-EOB-DTPA produces a favorable contrast effects in the mouse liver, indicating its potential in investigating mouse models of liver diseases. The contrast effects vary between conscious mice and anesthetized mice and among anesthetic agents used.     

Temporal formation of optical anisotropy and surface relief during polarization holographic recording in polymethylmethacrylate with azobenzene side groups

The formation of polarization holographic gratings with both optical anisotropy and surface relief (SR) deformation was studied for polymethylmethacrylate with azobenzene side groups. Temporal contributions of isotropic and anisotropic phase gratings were simultaneously determined by observing transitional intensity and polarization states of the diffraction beams and characterizing by means of Jones calculus. To clarify the mechanism of SR deformation, cross sections of SR were characterized based on the optical gradient force model; experimental observations were in good agreement with the theoretical expectation. We clarified that the anisotropic phase change originating in the reorientation of the azobenzene side groups was induced immediately at the beginning of the holographic recording, while the response time of the isotropic phase change originating in the molecular migration due to the optical gradient force was relatively slow.     

Impact of Multi-Component Surrogates on the Performances,Pollutants, and Exergy of IC Engines

Even though there is a pressing interest in clean energy sources, compression ignition (CI) engines, also called diesel engines, will remain of great importance for transportation sectors as well as for power generation in stationary applications in the foreseeable future. In order to promote applications dealing with complex diesel alternative fuels by facilitating their integration in numerical simulation, this paper targets three objectives. First, generate novel diesel fuel surrogates with more than one component. Here, five surrogates are generated using an advanced chemistry solver and are compared against three mechanisms from the literature. Second, validate the suggested reaction mechanisms (RMs) with experimental data. For this purpose, an engine configuration, which features a reacting spray flow evolving in a direct-injection (DI), single-cylinder, and four-stroke motor, is used. The RNG k-Epsilon coupled to power-law combustion models is applied to describe the complex in-cylinder turbulent reacting flow, while the hybrid Eulerian-Lagrangian Kelvin Helmholtz-Rayleigh Taylor (KH-RT) spray model is employed to capture the spray breakup. Third, highlight the impact of these surrogate fuels on the combustion properties along with the exergy of the engine. The results include distribution of temperature, pressure, heat release rate (HRR), vapor penetration length, and exergy efficiency. The effect of the surrogates on pollutant formation (NOX, CO, CO2) is also highlighted. The fifth surrogate showed 47% exergy efficiency. The fourth surrogate agreed well with the maximum experimental pressure, which equaled 85 Mpa. The first, second, and third surrogates registered 400, 316, and 276 g/kg fuel, respectively, of the total CO mass fraction at the outlet. These quantities were relatively higher compared to the fourth and fifth RMs.     

Temperature and matrix effects on competitive intermolecular and intramolecular reaction of benzylchlorocarbenes in ethanol

Benzylchlorocarbenes generated photolytically from diazirines in EtOH afford chlorostyrenes and acetals, whose distributions are sensitive to the reaction temperature.     

Development of effective cross-linking method for bioactive substance--enzyme immobilization using glutaraldehyde oligomers

When a 10% aqueous solution of glutaraldehyde (GA) was alkalized to pH 8.5 in borate buffer solution and heated at 60 degrees C, the ultraviolet spectrum of GA solution showed two distinct absorption maxima. The one at 280 nm with a weak absorbance ascribable to the C = O bond in the aldehyde group shifted to near 300 nm after 50 min with a slight increase in its intensity. Another maximum at 235 nm with a strong absorbance was ascribable to the C = C bond of the alpha,beta-unsaturated aldehyde group which was formed by aldol condensation reaction of GA monomer, and its absorbance increased markedly with increasing reaction time. The high performance liquid chromatography (HPLC) analysis with detection at 235 nm indicated that several GA oligomers were formed by the alkali treatment and their concentrations increased. The cross-linking ability of these oligomers was examined by immobilizing enzymes (alcohol dehydrogenase (ADH), glutamate dehydrogenase (GLDH] to an aminated polymer gel matrix by reaction with the treated GA solution. The enzyme activities increased with increasing concentration of GA oligomers. Then, the GA oligomers were isolated and used as the cross-linking agent. The activities of ADH and GLDH were 4-fold and 13-fold higher, respectively, than those obtained by using untreated GA solution, while the total amounts of immobilized enzymes were almost unchanged. These results suggest that GA oligomers may act as cross-linkers in a manner different from the generally accepted Schiff base formation reaction; a possible mechanism may involve addition reaction of an amino group to the double bond in the aldol condensate of GA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Two-dimensional correlation gel permeation chromatography (2D GPC) study of the CH<Subscript>3</Subscript>SO<Subscript>3</Subscript>H-catalyzed polymerization of triethoxysilyl-terminated polystyrene. Molecular weight effect on the aggregate–aggregate interactions

The two-step polymerization process of two well-defined polymeric silane coupling agents, triethoxysilyl-terminated polystyrene with molecular weights equal to 2400 [TESi-PS (2400)] and 8000 [TESi-PS (8000)], catalyzed by 0.1 mol/kg CH₃SO₃H, was traced as a function of reaction time using gel-permeation chromatography (GPC). Two sets of GPC traces, collected during the condensation, were then converted to two-dimensional (2D) correlation spectra by using generalized 2D correlation theory. The 2D correlation spectra elucidated details of the aggregate–aggregate correlations [in particular, the difference between the correlations of TESi-PS (2400) and TESi-PS (8000)], thus demonstrating the effect of aggregation on the polymerization.     

A pair-excitation MCSCF calculation based on CNDO/INDO approximation I

Second-order multiconfigurational self-consistent field (MCSCF ) calculation has been programmed on the basis of CNDO /INDO molecular orbital bases, in which the configuration space employed is restricted within pair-excitations. Test calculations have been carried out for 17 small molecules. All the MCSCF ground states of these molecules have been successfully converged to their respective optimal states by employing a simple weighting scheme. This procedure provides a great savings in computer time. The MCSCF calculation on azetidine required only 27 min on a HITAC M-680H. The MCSCF energies of HF, F₂, and BH show improved behaviors up to large atomic distances (～7au).     

Uptake of Au(III) Ions by Aluminum Hydroxide and Their Spontaneous Reduction to Elemental Gold (Au(0))

The behavior of AuCl(4)(-) ions during the formation of aluminum hydroxide at pH 6 was examined. With an increase in NaCl concentration, the content of gold taken up by aluminum hydroxide decreased, suggesting that chloro-hydroxy complexes of Au(III) ion were taken up due to the formation of Al-O-Au bonds. It was found unexpectedly that the Au(III) ions taken up were spontaneously reduced to elemental gold without addition of a specific reducing reagent and then colloidal gold particles were formed. The mechanisms for the uptake of Au(III) ions by aluminum hydroxide and for their spontaneous reduction are discussed. Copyright 2001 Academic Press.