Accelerated physical ageing of poly(1,4-cyclohexylenedimethylene--2,2,4,4-tetramethyl-1,3-cyclobutanediol terephthalate).

Successfully evaluating plastic lifetime requires understanding of the relationships between polymer dynamics and mechanical performance as a function of thermal ageing. The relatively high ( = 110 °C) of poly(1,4-cyclohexylenedimethylene--2,2,4,4-tetramethyl-1,3-cyclobutanediol terephthalate) (PCTT) renders it useful as a substituent for PET in higher temperature applications. This work links thermal ageing and mechanical performance of a commercial PCTT plastic after exposure to 40-80 °C for up to 2950 h.

Crystal structure of quinone-dependent alcohol dehydrogenase from Pseudogluconobacter saccharoketogenes. A versatile dehydrogenase oxidizing alcohols and carbohydrates.

The quinone-dependent alcohol dehydrogenase (PQQ-ADH, E.C. 1.

A novel type carbohydrate-binding module identified in alpha-glucan, water dikinases is specific for regulated plastidial starch metabolism.

The phosphorylation of the amylopectin fraction of starch catalyzed by the alpha-glucan, water dikinase (GWD, EC 2.7.9.

Small-number statistics near the clustering transition in a compartmentalized granular gas.

Statistical fluctuations are observed to profoundly influence the clustering behavior of granular material in a vibrated system consisting of two connected compartments. When the number of particles N is sufficiently large ( N approximately 300 is sufficient), the clustering follows the lines of a standard second-order phase transition and a mean-field description works. For smaller N , however, the enhanced influence of statistical fluctuations breaks the mean-field behavior.

Competitive clustering in a bidisperse granular gas: experiment, molecular dynamics, and flux model.

A compartmentalized bidisperse granular gas clusters competitively [Phys. Rev. Lett.

A novel isoform of glucan, water dikinase phosphorylates pre-phosphorylated alpha-glucans and is involved in starch degradation in Arabidopsis.

An Arabidopsis thaliana gene encoding a homologue of the potato alpha-glucan, water dikinase GWD, previously known as R1, was identified by screening the Arabidopsis genome and named AtGWD3. The AtGWD3 cDNA was isolated, heterologously expressed and the protein was purified to apparent homogeneity to determine the enzymatic function. In contrast to the potato GWD protein, the AtGWD3 primarily catalysed phosphorylation at the C-3 position of the glucose unit of preferably pre-phosphorylated amylopectin substrate with long side chains.

Alpha-glucan, water dikinase (GWD): a plastidic enzyme with redox-regulated and coordinated catalytic activity and binding affinity.

The recently discovered potato tuber (Solanum tuberosum) alpha-glucan, water dikinase (GWD) (formerly known as R1) catalyzes the phosphorylation of starch by a dikinase-type reaction mechanism in which the beta-phosphate of ATP is transferred to either the C-6 or the C-3 position of the glucosyl residue of starch. In the present study, we found that the GWD enzyme is inactive in the oxidized form, which is accompanied by the formation of a specific intramolecular disulfide bond as determined by disulfide-linked peptide mapping. The regulatory properties of this disulfide linkage were confirmed by site-directed mutagenesis studies.

Impact on soft sand: void collapse and jet formation.

Very fine sand is prepared in a well-defined and fully decompactified state by letting gas bubble through it. After turning off the gas stream, a steel ball is dropped on the sand. On impact of the ball, sand is blown away in all directions ("splash") and an impact crater forms.

Functional domain organization of the potato alpha-glucan, water dikinase (GWD): evidence for separate site catalysis as revealed by limited proteolysis and deletion mutants.

The potato tuber (Solanum tuberosum) GWD (alpha-glucan, water dikinase) catalyses the phosphorylation of starch by a dikinase-type reaction mechanism in which the beta-phosphate of ATP is transferred to the glucosyl residue of amylopectin. GWD shows sequence similarity to bacterial pyruvate, water dikinase and PPDK (pyruvate, phosphate dikinase). In the present study, we examine the structure-function relationship of GWD.

Functional characterization of alpha-glucan,water dikinase, the starch phosphorylating enzyme.

GWD (alpha-glucan,water dikinase) is the enzyme that catalyses the phosphorylation of starch by a dikinase-type reaction in which the beta-phosphate of ATP is transferred to either the C-6 or the C-3 position of the glycosyl residue of amylopectin. GWD shows similarity in both sequence and reaction mechanism to bacterial PPS (pyruvate,water dikinase) and PPDK (pyruvate,phosphate dikinase). Amino acid sequence alignments identified a conserved histidine residue located in the putative phosphohistidine domain of potato GWD.

Influence of solitons on the transition to spatiotemporal chaos in coupled map lattices.

We study the transition from laminar to chaotic behavior in deterministic chaotic coupled map lattices and in an extension of the stochastic Domany-Kinzel cellular automaton [E. Domany and W. Kinzel, Phys.

Competitive clustering in a bidisperse granular gas.

A bidisperse granular gas in a compartmentalized system is experimentally found to cluster competitively: Depending on the shaking strength, the clustering can be directed either towards the compartment initially containing mainly small particles or to the one containing mainly large particles. The experimental observations are quantitatively explained within a flux model.

Starch phosphorylation: a new front line in starch research.

Starch is the primary energy reserve in higher plants and is, after cellulose, the second most abundant carbohydrate in the biosphere. It is also the most important energy source in the human diet and, being a biodegradable polymer with well-defined chemical properties, has an enormous potential as a versatile renewable resource. The only naturally occurring covalent modification of starch is phosphorylation.

"Sausage-string" appearance of arteries and arterioles can be caused by an instability of the blood vessel wall.

Vascular damage induced by acute hypertension is preceded by a peculiar pattern where blood vessels show alternating regions of constrictions and dilations ("sausages on a string"). The pattern occurs in the smaller blood vessels, and it plays a central role in causing the vascular damage. A related vascular pattern has been observed in larger vessels from several organs during angiography.

Truncation of the amino terminus of branching enzyme changes its chain transfer pattern.

Previous work has reported the production of an Escherichia coli branching enzyme with a 112-residue deletion at the amino terminal by limited proteolysis. Here, we study the chain transfer pattern of this enzyme. Gel-permeation chromatography of in vitro branched amylose shows that the truncated branching enzyme transfers fewer short chains (degree of polymerization [d.