A rate-dependent two-dimensional free energy model for ferroelectric single crystals

The one-dimensional free energy model for ferroelectric materials developed by Smith et al. [29–31] is generalized to two dimensions. The two-dimensional free energy potential proposed in this paper consists of four energy wells that correspond to four variants of the material. The wells are separated by four saddle points, representing the barriers for 90°-switching processes, and a local maximum, across which 180°-switching processes take place. The free energy potential is combined with evolution equations for the variant fractions based on the theory of thermally activated processes. The model is compared to recent measurements on BaTiO₃ single crystals by Burcsu et al. [8], and predicitions are made concerning the response to the application of in-plane multi-axial electric fields at various frequencies and loading directions. The kinetics of the 90°- and 180°-switching processes are discussed in detail.     

The synthesis and conformational analysis of amino acid-tetrahydroanthranilic acid hybrids

The optimization of a palladium-catalyzed amidation reaction providing a new class of amino acid-tetrahydroanthranilic acid derivatives has been achieved. The scope of the reaction and preliminary conformational analysis of the resulting series of molecules is discussed.     

Rapid high-performance liquid chromatographic analysis of adenovirus type 5 particles with a prototype anion-exchange analytical monolith column

To support effective process development there is a requirement for rapid analytical methods that can identify and quantitate adenoviral particles throughout the manufacturing process, from cellular lysate through to purified adenovirus. An anion-exchange high-performance liquid chromatography method for the analysis of adenovirus type 5 (Ad5) particles has been developed using a novel quaternary amine monolithic column (Bio-Monolith QA, Agilent). The developed method separates intact Ad5 from contaminating proteins and DNA, thus allowing analysis of non-purified samples during process development. Regeneration conditions were incorporated to extend the functional life of the column. Once developed, the method was qualified according to performance criteria of repeatability, intermediate precision and linearity. The linear working range of analysis was established between 7.5 × 10⁸ to at least 2.4 × 10¹⁰ viral particles (3 × 10¹⁰ to 9.6 × 10¹¹ viral particles/mL), with a correlation coefficient of 0.9992. Relative standard deviations (RSDs) for intra- and inter-day repeatability and precision for retention time and peak area were less than 1 and 2.5%, respectively.     

Microwave Digestion of Thermoluminescent Aluminium-Oxide Powders and Determination of Trace Impurities by Inductively Coupled Plasma Optical Emission Spectroscopy

 Five commercial and three laboratory prepared thermoluminescent aluminium-oxide powders as well as three reference samples were digested by a microwave digestion system and the impurities were determined by ICP-OES. The physico-chemical properties of the different samples were found to influence highly the decomposition efficiency. Optimized decompositi on parameters were determined for the samples with different physico-chemical properties (phase composition, grain size). The detection limits of the impurities of interest are presented, the analysis results for the aluminium- oxide dosimetric samples and the standards are given as well for Be, Ca, Ce, Cu, Fe, Cd, Mg, Mo, Na, Ni, Ti and Zn in the < 2–400 μg/g range. Received August 24, 1999. Revision December 1, 1999.     

3-Hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine-2-carboxylates—fast access to a heterocyclic scaffold for HIV-1 integrase inhibitors

An efficient and reliable synthesis of the heterocyclic scaffold methyl-3-hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine-2-carboxylate is described. The scope of the synthesis regarding the introduction of substituents on the pyrido-fused ring is explored.     

Small x resummation with quarks: Deep-inelastic scattering

We extend our previous results on small-x resummation in the pure Yang–Mills theory to full QCD with n_f quark flavours, with a resummed two-by-two matrix of resummed quark and gluon splitting functions. We also construct the corresponding deep-inelastic coefficient functions, and show how these can be combined with parton densities to give fully resummed deep-inelastic structure functions F₂ and F_L at the next-to-leading logarithmic level. We discuss how this resummation can be performed in different factorization schemes, including the commonly used scheme. We study the importance of the resummation effects by comparison with fixed-order perturbative results, and we discuss the corresponding renormalization and factorization scale variation uncertainties. We find that for x below 10⁻² the resummation effects are comparable in size to the fixed order NNLO corrections, but differ in shape. We finally discuss the phenomenological impact of the small-x resummation, specifically in the extraction of parton distribution from present day experiments and their extrapolation to the kinematics relevant for future colliders such as the LHC.