A codeine radioimmunoassay exhibiting insignificant cross-reactivity with morphine

Viability of canine heart valve leaflet fibroblasts was assessed after varying periods of sterilization and storage in antibiotic-nutrient solution. Tissue culture and assessment of protein and collagen synthesis showed that tissue obtained under optimal conditions rarely retains viability beyond 3 weeks in antibiotic-nutrient solution and is severely impaired after 2 weeks. This casts serious doubts on viability in current clinical homograft valve practice.     

Microstructure Evolution and Cation Interdiffusion in Thin Sm2O3 Films on CeO2 Substrates

Samaria (Sm₂O₃) thin films with a thickness of 180 nm were deposited on polycrystalline CeO₂ substrates by pulsed layer deposition to study phase formation and bulk cation interdiffusion in the Ce_1?xSm_xO_2?x/2 system after annealing at temperatures between 987°C and 1266°C. Transmission electron microscopy combined with electron diffraction and analytical techniques was applied for phase determination. The cubic fluorite and cubic bixbyite phases were observed at low and intermediate Sm concentrations. The monoclinic phase occurs only at very high Sm concentrations due to the low Ce‐solubility in Sm₂O₃. Furthermore, a cubic phase with I2₁3 structure was observed at higher Sm concentrations. Cation interdiffusion coefficients were derived from Sm concentration profiles across the Sm₂O₃/CeO₂ interface using the diffusion–couple solution of the diffusion equation. The temperature dependence of interdiffusion coefficients is well described by an Arrhenius‐type relation, which yields an activation enthalpy of 2.26 eV/atom for bulk cation interdiffusion.     

Electronic Circular Dichroism Spectroscopy of 1-(R)-Phenylethanol: The “Sector Rule” Revisited and an Exploration of Solvent Effects

The sensitivity of the electronic circular dichroism (ECD) of a chiral molecule to structural and environmental changes has been investigated using 1-(R)-phenylethanol (1-PE) as the benchmark solute and cyclohexane and water as the trial solvents. Rotatory strengths associated with the π → π* (¹L_b) electronic transition have been calculated ab initio for: (a) isolated 1-PE, as a function of the dihedral angles within its chiral side chain and between the side chain and the aromatic ring: these confirm the validity of the empirical “sector rule” but with the signs reversed; (b) the singly and doubly hydrated clusters of 1-PE, isolated in the gas phase; (c) 1-PE and its singly and doubly hydrated clusters embedded in a polarizable dielectric continuum; and (d) 1-PE in an aqueous solution interacting with the local hydration shell and with the polarizable dielectric continuum, using averaged solute structures computed from the fluctuating solute and solvent configurations generated via molecular dynamics simulations. The ab initio calculations (conducted with GAUSSIAN 98) employed configuration interaction singles (CIS) or time-dependent density functional theory (TD-DFT) procedures using basis sets of double- and triple-zeta quality. The results have been related to experimental observations and discussed in terms of changes in the molecular geometry and solvent-induced perturbations.     

Response of immobilized bacillus subtilis α‐amylase to high pressure treatment

Immobilized enzymes, advantageous for use in bioreactors, are difficult to decontaminate. Inactivation of microorganisms by high hydrostatic pressure could be a gentle decontamination method, provided the immobilized enzyme is stable enough. Loss in activity of α‐amylase from Bacillus subtilis covalently bound to sepharose, after 10–30 minutes of pressure treatment at 300, 450 und 600 MPa at 50 and 70 °C and pH 8, and after 10–30 minutes of heat treatment at 50 and 70 °C and pH 8, was distinctly lower than that of equally treated non‐immobilized B. subtilis α‐amylase with and without sepharose. At 100 MPa reaction was accelerated by 5 %.     

RHEOLOGY, PARTICLE SIZE DISTRIBUTION, AND ASPHALTENE DEPOSITION OF VISCOUS ASPHALTIC CRUDE OIL-IN-WATER EMULSIONS FOR PIPELINE TRANSPORTATION

The rheology of an asphaltic heavy crude oil-in-water emulsions stabilized by an anionic (RN) and a nonionic (TEP) surfactants individually or in a mixture has been studied. The investigated crude oil has a non-Newtonian, time dependent, shear thickening, rheopectic behavior with a relatively high yield stress. The relatively high yield stress of this crude oil is attributed to the presence of a relatively high asphaltene and resins content. The viscosity ofhe crude oil decreases when it is emulsified with synthetic formation water in the form of an oil-in-water type of emulsion using a nonionic or an anionic surfactant. It has been found that, the maximum oil content required for forming an oil-in-water emulsion of acceptable viscosity is the 60% oil-containing emulsion. However, the 70% oil-containing emulsion is not an oil-in-water type of emulsion but it is rather a complicated mixture of oil-in-water-in-oil type of emulsion. The presence of the anionic and the nonionic surfactants together has a synergistic effect in decreasing the total surfactant concentration required to stabilize the emulsion and to form low viscosity emulsion. It has been emphasized that the nonionic surfactant has a positive contribution in forming emulsions with low viscosity. Meanwhile, the anionic surfactant contributes in stabilizing the emulsion at lower concentrations. Flocculation point measurements showed that the added surfactants caused no sign of asphaltene deposition. This implies that it is safe to use the investigated surfactants in forming oil-in-water emulsion for viscous asphaltic crude oils without any fear of asphaltene deposition.     

High pressure/temperature treatments to inactivate highly infectious prion subpopulations

High hydrostatic pressure can be used for gentle pasteurization of food as well as a physical parameter to study the stability and energetics of biomolecules. High pressure has been recently postulated as a feasible technology to decontaminate scrapie infectious materials. Here we discuss the kinetic parameters driving the inactivation of the Transmissible Spongiform Encephalopathy agents and the perspectives of pressure as a thermodynamic parameter to obtain a deeper insight into the aggregation of the 263K strain of scrapie. At 60–80 °C an efficient pressure inactivation of infectious scrapie prions was observed during short pressure treatments at 800 MPa (3 × 5 min cycles). However, discrepancies between in vivo infectivity counts and the results of an enzyme immunoassay further revealed that the infectivity was inactivated faster and much more efficiently than PrP^res was degraded, indicating that pressure affects a highly infectious subpopulation of scrapie prions.

Industrial relevance

Conventional inactivation methods for the agents of the Transmissible Spongiform Encephalopathies are not compatible with food processing due to the required aggressive conditions. High pressure assisted thermal sterilization methods are nowadays attracting attention as a food preservation technology able to preserve quality attributes. Here the stark effects in the secondary prion structure of high pressure combined with heat below the usual denaturing conditions were investigated with specific tests. This technology was proven to be a feasible alternative to achieve the decontamination of TSE risk materials at milder conditions. Kinetic data provided here should be useful to establish criteria to inactivate prions under pressure.     

Magnetic order in proton irradiated graphite: Curie temperatures and magnetoresistance effect

Defect induced magnetic order is a new phenomenon in material science that refers to the triggering and manipulation of magnetic order and magnetic moments in nominally non-magnetic materials by lattice defects and/or non-magnetic add atoms. A noticeable example of this effect is the magnetic order at room temperature produced by proton irradiation of graphite. In this work we have managed to increase the ferromagnetic signal by cooling the graphite samples down to 110 K during proton irradiation, diminishing in this way annealing effects. SQUID measurements of the magnetization show a fluence dependent Curie temperature. The longitudinal magnetoresistance shows an irreversible behavior similar to that found in ferromagnetic films indicating spin/domain reorientation effects. The observed magnetoresistance effects and Curie temperatures above room temperature are promising facts that may lead to useful carbon-based devices in the near future.     

The improved STIM tomography set-up at LIPSION: Three-dimensional reconstruction of biological samples

The feasibility of tomographic reconstruction of biological specimens using scanning transmission ion microscopy (STIM) has already been demonstrated in the past. However, in previous experiments at Leipzig the resolution was limited by an insufficient accuracy of goniometer motion, which resulted in a blurred alignment of the projections. The new stage and goniometer at the LIPSION accelerator laboratory allow a more precise rotation of the sample. Furthermore, a new software was developed, which includes efficient algorithms to correct misalignment errors. STIM tomography experiments using a proton and a molecular beam respectively were carried out on a rust mite (Aculus schlechtendali), on average 25 μm thick, and on unicellular organisms (Thaumatomonas coloniensis) with a diameter below 5 μm. The backprojection of filtered projections (bfp) algorithm was employed for the three-dimensional reconstruction. The reconstruction revealed many structural details including spherical grains of higher density inside the mite’s body of yet unknown origin.