Lower semicontinuity of quasi-convex integrals in BV

Some boundedness properties for an extension operator are proved and used together with techniques of Maly [24], Meyers [29], Fonseca and Müller [13] and Fonseca and Marcellini [12] to obtain lower semicontinuity results in BV for quasiconvex integrals of super-linear growth. Received January 25, 1997 / Accepted October 3, 1997     

Internal audits in private medical laboratory practice – a Finnish experience in 1996–2000

Internal audits inherently effect quality improvement, and concrete results can be expected by careful planning. As audits should improve the quality system in situ, the development of audits should not be neglected. ISO/IEC 17025 describes the objectives of internal audits and management reviews in more detail compared to the former standards EN 45001 and ISO/IEC Guide 25, although the main features are unchanged. This addresses continuous surveillance of the current practice. A brief questionnaire on vertical audits was distributed to 74 of 120 employees at a Finnish private medical laboratory, Medix Laboratories Ltd. A positive feed-back was received from the current management of audits. However, the study revealed that continuous supervision of audits is needed. Many employees were not willing to perform audits if they had no previous experience. Additionally, audits performed at the workbench were not considered as the best possible for fruitful discussions. Received: 20 February 2001 Accepted: 30 November 2001     

Decrease in activity caused by hydrogen in Ziegler-Natta ethene polymerisation

In this study we prepared seven different Ziegler-Natta catalysts and polymerised them at different hydrogen concentrations in order to investigate their kinetic behaviour during polymerisation. The objective was to see whether the results corresponded to what could be expected on the basis of Kissin's β-agostic deactivation theory. According to this theory, hydrogen causes the formation of dormant sites due to the formation of β-agostic coordination from the ethyl groups formed after hydrogen termination. According to this theory, the more hydrogen that is used, the more β-agostic coupling and the smaller percentage of Ti in a polymerising state. This β-agostic coupling would thus explain the lower activity level seen in polymerisation where more hydrogen has been used.The results of this study showed that none of the catalysts showed the kind of behaviour that would correspond to what could be predicted on the basis of Kissin's theory. Deactivation could be detected only when a lower amount of hydrogen was used. When higher amounts of hydrogen were used in polymerisation there was a clear delay in activation time of the catalysts. This particularly seemed to be the case for catalysts where Ti was present as Ti(IV). This delay in the activation of the catalyst caused a decrease in activity in addition to the normal decrease in activity due to hydrogen replacing C₂^′′ in the polymerisation process.The only catalyst showing no delay in activation was a silica-based PE ZN catalyst where the Ti was already in trivalent form. In this case no decrease in activity was observed in addition to the normal decrease in activity caused by hydrogen replacing C₂^′′ in the polymerisation process.     

Beta-sheet preferences from first principles

The natural amino acids have different preferences of occurring in specific types of secondary protein structure. Simulations are performed on periodic model beta-sheets of 14 different amino acids, at the level of density functional theory, employing the generalized gradient approximation. We find that the statistically observed beta-sheet propensities correlate very well with the calculated binding energies. Analysis of the calculations shows that the beta-sheet propensities are determined by the local flexibility of the individual polypeptide strands.     

Identification of phage antibodies toward the Werner protein by selection on Western blots

A procedure was established for selecting phage antibodies (phage-abs) from phage-displayed antibody repertoires by panning against proteins, separated by sodium dodecyl phosphate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotted onto nitrocellulose membranes (Western blots). This immobilization strategy is applicable for secondary rounds of panning in selections against semipurified proteins, and directs the selection toward antibodies suitable as immunochemical reagents in Western blots. In model experiments, enrichment factors as high as 1.9x10(5) were obtained in a single round of panning. Furthermore, we demonstrate the application of this approach by selection of phage-abs recognizing the human Werner protein, which is defective in a premature aging syndrome.     

Ortho lithiation-in situ borylation of substituted morpholine benzamides

Morpholine amides are cheap and safe alternative to Weinreb amides as acylating agents of organometallic species. Herein, the in-situ lithiation/borylation of 18 ortho- meta- and para-substituted morpholine benzamides has been investigated. 10 of the 18 substrates provided the desired boronic esters as the major isomer (>90% regioselectivity) in crude isolated yields ranging from 68 to 93%. The synthetic usability of such building blocks was subsequently illustrated via the synthesis of a kinase inhibitor.