Pion correlations and resonance effects in [`(p)]p\bar pp annihilation at rest to 2π+2π-π0

We study ππ correlations in the exclusive reaction at rest with complete reconstruction of the kinematics for each event. Inclusive and differential distributions properly normalized show an enhancement for small invariant masses M ₊₊,M _-- of like-pion pairs. An even stronger enhancement is seen for the double differential distributions for low pion-pair masses. The signal is strongest when the π₀ energy is large and much weaker when this energy is small. Dynamical models with resonances in the final state are confronted with the data. For the kinematic situation where the ρ3π channel is important the simulation predicts a large pion correlation for the double differential density, qualitatively explaining the observed bahaviour. The stochastic HBT mechanism is not supported by these findings for the exclusive annihilation reaction studied.     

Quantitative Comparison of the Antimicrobial Efficiency of Leaching versus Nonleaching Polymer Materials

New antimicrobial materials will be more and more in the focus for hygienic and clinical disease control. Antimicrobial materials have to be distinguished in leaching and nonleaching materials. For many applications of antimicrobial materials on implants the use of nonleaching materials is essential. Therefore, the antimicrobial efficiency of leaching and nonleaching polymers has been investigated quantitatively in vitro in direct comparison on a highly relevant implant of central venous catheters (CVCs) using a well‐established called Certika test. This test is especially designed to test antimicrobial properties of leachable and nonleachable materials. This contribution demonstrates that newly developed nonleaching antimicrobial CVCs are equivalent to conventional leaching CVC systems in their antimicrobial performance against gram‐positive and gram‐negative bacteria, as well as Candida species. The use of new nonleaching antimicrobial polymers as shown here for CVCs represents a different mode of action with the aim to prevent infections also with antibiotic‐resistant strains and reduced side effects.

     

Substrate specificity and function of acetylpolyamine amidohydrolases from <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis>

Background

Pseudomonas aeruginosa, a Gram-negative, aerobic coccobacillus bacterium is an opportunistic human pathogen and worldwide the fourth most common cause of hospital-acquired infections which are often high mortality such as ventilator-associated pneumoniae. The polyamine metabolism of P. aeruginosa and particularly the deacetylation of acetylpolyamines has been little studied up to now. Results with other bacterial pathogens e.g., Y. pestis suggest that polyamines may be involved in the formation of biofilms or confer resistance against certain antibiotics.

Results

To elucidate the role of acetylpolyamines and their enzymatic deacetylation in more detail, all three putative acetylpolyamine amidohydrolases (APAHs) from P. aeruginosa have been expressed in enzymatic active form. The APAHs PA0321 and PA1409 are shown to be true polyamine deacetylases, whereas PA3774 is not able to deacetylate acetylated polyamines. Every APAH can hydrolyze trifluoroacetylated lysine-derivatives, but only PA1409 and much more efficiently PA3774 can also process the plain acetylated lysine substrate. P. aeruginosa is able to utilize acetylcadaverine and acetylputrescine as a carbon source under glucose starvation. If either the PA0321 or the PA1409 but not the PA3774 gene is disrupted, the growth of P. aeruginosa is reduced and delayed. In addition, we were able to show that the APAH inhibitors SAHA and SATFMK induce biofilm formation in both PA14 and PAO1 wildtype strains.

Conclusions

P. aeruginosa has two functional APAHs, PA0321 and PA1409 which enable the utilization of acetylpolyamines for the metabolism of P. aeruginosa. In contrast, the physiological role of the predicted APAH, PA3774, remains to be elucidated. Its ability to deacetylate synthetic acetylated lysine substrates points to a protein deacetylation functionality with yet unknown substrates.

     

Liquid chromatographic method for quantitation of patulin at 10 ng/mL in apple-based products intended for infants: interlaboratory study

An interlaboratory trial for the determination of patulin in apple juice and fruit puree was conducted, involving 17 participants representing a cross section of industry, official food control, and research facilities. Mean recoveries reported ranged from 74 (10 ng/g) to 62% (25 ng/g) for apple juice and from 72 (25 ng/g) to 74% (10 ng/g) for fruit puree. Based on results for spiked samples (blind pairs at 2 levels), as well as naturally contaminated samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) in juice ranged from 8.0 to 14.3% and in puree from 3.5 to 9.3%. The relative standard deviation for reproducibility (RSD(R)) in juice ranged from 19.8 to 39.5% and in puree from 12.5 to 35.2%, reflecting HORRAT values from 0.6 to 1.0 for juice and 0.4 to 0.9 for puree. The method showed acceptable within-laboratory and between-laboratory precision for each matrix, as required by current European legislation.     

A novel solid-phase linker strategy for the side-chain anchoring of arginine: an expeditious route to arginine 7-amido-4-methylcoumarins

A novel linker strategy for the efficient side-chain anchoring of arginine is described. The utility of this approach was demonstrated by the facile synthesis of arginine-specific fluorogenic peptide substrates by standard Fmoc solid phase peptide synthesis methods.     

Niederkoordinierte Phosphorverbindungen. 60 [1]. Reaktionen von Iminomethylidenphosphanen mit Trimethylsilylphosphanen

Low-Coordinated Phosphorus Compounds. 60. Reactions of Iminomethylidenphosphanes with Trimethylsilylphosphanes The preparation of the new, monomer stable N-n-propyl-P-(2,4,6-tri-tertbutylphenyl)iminomethylidenphosphane 1 c is presented. The reactions of this compound and those of the already known iminomethylidenphosphanes 1a, b with trimethylsilylphosphanes are described. In non-polar solvents, 1,3-diphosphapropenes 4a—h respectively 1,3,4-triphospha-1-butenes 6a—d are obtained. In polar solvents, the reaction of 1b, c with phenyl-bis(trimethylsilyl) phosphane 3d results in the formation of 1,3,5-triphospha-1,4-pentadienes 7a, b and 8a, b through double addition. While tempering the new phosphacumulene 1c in solution, dimerisation occurs and yields the 1,3-diphosphetane 2c . The reaction of the 1,2-bis(trimethylsilyl)diphosphane 5b with 1c in acetonitrile produces the new 1,3,4,6-tetraphospha-1,5-hexadiene 9 . In contrast to analogous compounds with sterically less pretentious substituents at the double-bonded phosphorous, 9 shows no Cope-rearrangement.     

Gas-phase detection of HSOH: synthesis by flash vacuum pyrolysis of di-tert-butyl sulfoxide and rotational-torsional spectrum

Gas-phase oxadisulfane (HSOH), the missing link between the well-known molecules hydrogen peroxide (HOOH) and disulfane (HSSH), was synthesized by flash vacuum pyrolysis of di-tert-butyl sulfoxide. Using mass spectrometry, the pyrolysis conditions have been optimized towards formation of HSOH. Microwave spectroscopic investigation of the pyrolysis products allowed-assisted by high-level quantum-chemical calculations--the first measurement of the rotational-torsional spectrum of HSOH. In total, we have measured approximately 600 lines of the rotational-torsional spectrum in the frequency range from 64 GHz to 1.9 THz and assigned some 470 of these to the rotational-torsional spectrum of HSOH in its ground torsional state. Some 120 out of the 600 lines arise from the isotopomer H(34)SOH. The HSOH molecule displays strong c-type and somewhat weaker b-type transitions, indicating a nonplanar skew chain structure, similar to the analogous molecules HOOH and HSSH. The rotational constants (MHz) of the main isotopomer (A=202 069, B=15 282, C=14 840), determined by applying a least-squares analysis to the presently available data set, are in excellent agreement with those predicted by quantum-chemical calculations (A=202 136, B=15 279, C=14 840). Our theoretical treatment also derived the following barrier heights against internal rotation in HSOH (when in the cis and trans configurations) to be V(cis) approximately equal to 2216 cm(-1) and V(trans) approximately equal to 1579 cm(-1). The internal rotational motion results in detectable torsional splittings that are dependent on the angular momentum quantum numbers J and K(a).     

Inclusive measurement of [`(p)]\bar p annihilation at rest in gaseous hydrogen to final states containingρ andf2

Antiproton annihilation at rest in gaseous hydrogen (16 bar pressure) to the final states (770)X andf ₂(1270)X, whereX stands for one or more neutral mesons, has been studied at LEAR using the CPLEAR detector. Relative branching ratios are given forX = ⁰,2 ⁰, 3 ⁰ in the case, and forX = ⁰, in thef ₂ case. The annihilation channel has not been measured before. The fraction of P-wave annihilation is deduced from the ratiof ₂ ⁰/ ⁰ to be 0.38±0.07, in good agreement with the result previously obtained by CPLEAR from the ratioK ⁺ K ^-/ ^{+ -}.