Field Theory reformulated without self-energy parts.Divergence-free classical electrodynamics

A manifestly gauge-invariant hamiltonian formulation of classical electrodynamics has been shown to be relativistic invariant by the construction of the adequate generators of the Poincare Lie algebra [Physica, 76, No. 3, 421-444 (1974)]. The original formulation in terms of reduced distribution functions for the particles and the fields is applied here to the case of two charges interacting through a classical electrodynamical field. On the other hand, we have been able in previous work to introduce irreversibility at the fundamental level of description [Ann. Phys., 311, 314-349 (2004)] by reformulating field theory without self-energy parts by integrating all processes associated with self-energy in a kinetic operator, while keeping the equivalence with the original description [Prog. Theor. Phys.,109, 881-909 (2003)]. In this paper, the two approaches are combined to provide a formalism that enables the use of methods of statistical physics to tackle the problem of the divergence of the self-mass. Our approach leads to expressions that are finite even for point-like charged particles: the limit of a infinite cutoff can be taken in an harmless way on self consistent equations. In order to check our theory, we recover the power dissipated by radiation in geometries where the usual mass divergence does not play a roleComment: 82 pages, submitted Annals of Physics, Interpretation revised completel

Parktische kostprijs biologische melk 2010

In dit rapport is een praktische kostprijs biologische zuivel voor 2010 berekend op basis van de rekenmethodiek die in 2008 is ontwikkeld. Deze methodiek is gebaseerd op een breed draagvlak, praktische cijfers en levert een praktische kostprijs voor biologische koemelkproductie

Versatile Protecting-Group Free Tetrazolomethane Amine Synthesis by Ugi Reaction

The use of ammonia in the Ugi reaction is often problematic due to low yields and multiple side reactions. Here, we report the use of ammonia in the tetrazole Ugi variation providing a clean, good-to-high yielding reaction, especially with ketones as oxo components. The scope and limitations of this reaction and a structure–reactivity relationship are provided by performing >85 reactions. The primary amine component of the α-amino tetrazole is a versatile starting material for further reactions

Scenariostudie mono-vergisten op melkveebedrijf met veengrond

In een deskstudie zijn de effecten van mono-vergisten op een melkveebedrijf op veengrond met 150 koeien en 80 ha grasland onderzocht. De effecten van mono-vergisten op uitstoot van ammoniak en broeikasgassen (methaan en lachgas) zijn in beeld gebracht, evenals de gevolgen voor het inkomen. In deze studie zijn drie manieren van mono-vergisten onderzocht: Vergisten van mest die lang in de put heeft gezeten (oude mest). Vergisten van verse mest die kort in de put heeft gezeten. Vergisten van de feces fractie na primaire mestscheiding. Vergisten van verse mest leidt tot de grootste reductie van de emissies van methaan en ammoniak. Vergisten van feces is economisch het meest aantrekkelijk, terwijl oude mest vergisten leidt tot een daling van het inkomen. Dit vanwege een lage methaanopbrengst

Concise synthesis of tetrazole macrocycle

A concise two step synthesis of tetrazole containing macrocycles from readily accessible starting materials is presented. The first step comprises a chemoselective amidation of amino acid derived isocyanocarboxylicacid esters with unprotected symmetrical diamines to afford diverse α-isocyano-ω-amines. In the second step, the α-isocyano-ω-amines undergo an Ugi tetrazole reaction to close the macrocycle. Advantageously, this strategy allows short access to 11–19-membered macrocycles in which substituents can be independently varied at three different positions

‘Atypical Ugi’ tetrazoles

Amino acid-derived isocyano amides together with TMSN3, oxocomponents and 1° or 2° amines are common substrates in the Ugi tetrazole reaction. We surprisingly found that combining these substrates gives two different constitutional isomeric Ugi products A and B. A is the expected classical Ugi product whereas B is an isomeric product ('atypical Ugi') of the same molecular weight with the tetrazole heterocycle migrated to a different position. We synthesized, separated and characterized 22 different isomorphic examples of the two constitutional isomers of the Ugi reaction to unambiguously prove the formation of A and B. Mechanistic studies resulted in a proposed mechanism for the concomitant formation of A and B

A versatile, compartmentalised gut-on-a-chip system for pharmacological and toxicological analyses

A novel, integrated, in vitro gastrointestinal (GI) system is presented to study oral bioavailability parameters of small molecules. Three compartments were combined into one hyphenated, flow-through set-up. In the first compartment, a compound was exposed dynamically to enzymatic digestion in three consecutive microreactors, mimicking the processes of the mouth, stomach, and intestine. The resulting solution (chyme) continued to the second compartment, a flow-through barrier model of the intestinal epithelium allowing absorption of the compound and metabolites thereof. The composition of the effluents from the barrier model were analysed either offline by electrospray-ionisation-mass spectrometry (ESI-MS), or online in the final compartment using chip-based ESI-MS. Two model drugs, omeprazole and verapamil, were used to test the integrated model. Omeprazole was shown to be broken down upon treatment with gastric acid, but reached the cell barrier unharmed when introduced to the system in a manner emulating an enteric-coated formulation. In contrast, verapamil was unaffected by digestion. Finally, a reduced uptake of verapamil was observed when verapamil was introduced to the system dissolved in apple juice, a simple food matrix. It is envisaged that this integrated, compartmentalised GI system has potential for enabling future research in the fields of pharmacology, toxicology, and nutrition