How to Reach a Thousand-Second in-Plane Polarization Lifetime with 0.97-GeV/c Deuterons in a Storage Ring.

We observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10^{-29} e cm.

New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments.

A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by ν(s)=γG (γ is the Lorentz factor, G the gyromagnetic anomaly). At 970 MeV/c, the deuteron spins coherently precess at a frequency of ≈120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order 10^{-8}, and to 1×10^{-10} for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics; controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring.

Laser microdissection and cryogenic nuclear magnetic resonance spectroscopy: an alliance for cell type-specific metabolite profiling.

Laser microdissection was used as a tool to harvest secretory cavities (SC) from leaves of Dilatris pillansii Barker (Haemodoraceae) and from leaves and flowers of herbarium specimens of Dilatris corymbosa Berg. and Dilatris viscosa L. Cryogenic (1)H NMR spectroscopy and HPLC analysis of microdissected samples indicated specific accumulation of methoxyphenylphenalenones in the SC. The structures of two novel and a known natural product in the secretory tissue were confirmed by comparison with authentic compounds isolated from rhizomes and roots from which further phenylphenalenones and phenylphenalenone glucosides were isolated and identified by spectroscopic methods. How it will be possible to use the LMD technique to localize natural products in specific plant cell populations is also discussed.

A type III polyketide synthase from Wachendorfia thyrsiflora and its role in diarylheptanoid and phenylphenalenone biosynthesis.

Chalcone synthase (CHS) related type III plant polyketide synthases (PKSs) are likely to be involved in the biosynthesis of diarylheptanoids (e.g. curcumin and polycyclic phenylphenalenones), but no such activity has been reported. Root cultures from Wachendorfia thyrsiflora (Haemodoraceae) are a suitable source to search for such enzymes because they synthesize large amounts of phenylphenalenones, but no other products that are known to require CHSs or related enzymes (e.g. flavonoids or stilbenes). A homology-based RT-PCR strategy led to the identification of cDNAs for a type III PKS sharing only approximately 60% identity with typical CHSs. It was named WtPKS1 (W. thyrsiflora polyketide synthase 1). The purified recombinant protein accepted a large variety of aromatic and aliphatic starter CoA esters, including phenylpropionyl- and side-chain unsaturated phenylpropanoid-CoAs. The simplest model for the initial reaction in diarylheptanoid biosynthesis predicts a phenylpropanoid-CoA as starter and a single condensation reaction to a diketide. Benzalacetones, the expected release products, were observed only with unsaturated phenylpropanoid-CoAs, and the best results were obtained with 4-coumaroyl-CoA (80% of the products). With all other substrates, WtPKS1 performed two condensation reactions and released pyrones. We propose that WtPKS1 catalyses the first step in diarylheptanoid biosynthesis and that the observed pyrones are derailment products in the absence of downstream processing proteins.

Absorption cross section and photolysis of OIO.

Pulsed laser photolysis combined with transient absorption spectroscopy and resonance fluorescence was used to examine the photolysis of OIO at a number of wavelengths corresponding to absorption bands in its visible spectrum between approximately 530 and 570 nm. Photolysis at 532 nm was found to result in substantial depopulation of the absorbing ground state, enabling an estimate for the absorption cross section of OIO at 610.2 nm of (6 +/- 2) x 10(-18) cm2 molecule(-1) to be obtained. No evidence was found for I atom formation following photolysis of OIO at 532, 562.3, 567.9 and 573.8 nm, enabling an upper limit to the I atom quantum yield of < 0.05 (560-580 nm) and < 0.24 (532 nm) to be established.

Kinetics of the reactions of HO with methanol (210-351 K) and with ethanol (216-368 K).

Absolute rate coefficients for the reaction of hydroxyl radicals (HO) with methanol, HO + CH3OH --> products (R1), and with ethanol, HO + C2H5OH --> products (R2) were measured over a range of temperatures using pulsed laser photolytic generation of HO coupled to its time resolved detection by pulsed laser induced fluorescence. The accuracy of the rate constants obtained was enhanced by on-line optical absorption measurements of the alcohol concentration. The temperature dependence of the rate coefficients is given by: k1(210-351 K) = 6.67 x 10(-18) T2 exp(140/T) cm3 molecule(-1) s(-1) with a rate coefficient at room temperature of (9.3 +/- 0.7) x 10(-13) cm3 molecule(-1) s(-1). For k2 we obtained: k2(216-368 K) = 4.0 x 10(-12) exp(-42/T) and a room temperature rate coefficient of (3.35 +/- 0.17) x 10(-12) cm3 molecule(-1) s(-1). The total error (at 95% confidence) associated with the rate coefficients derived from the expressions describing the temperature dependence is estimated as 7% at all temperatures. The present results, which extend the database on these reactions to cover temperatures relevant for the upper troposphere, are compared to previously published measurements, and values of k1 and k2 are recommended for atmospheric modelling.

Phenalenones from Strelitzia reginae.

Phytochemical analysis of rhizomes of Strelitzia reginae resulted in the isolation and identification of an unusual new (1) and four known phenalenone-type compounds, which were identified using MS and NMR spectroscopic techniques. The occurrence of phenalenones in Strelitziaceae, which has been established for the first time, is of chemotaxonomic interest.

Variability of phenylpropanoid precursors in the biosynthesis of phenylphenalenones in Anigozanthos preissii.

Feeding experiments using 13C labelled precursors and NMR spectroscopic studies revealed general biosynthetic incorporation of phenylalanine and variable incorporation of cinnamic acid, p-coumaric acid, caffeic acid and ferulic acid into phenylphenalenones in root cultures of Anigozanthos preissii. Evidence was obtained for parallel pathways of phenylphenalenone biosynthesis, with respect to the left phenylpropanoid unit, and a sequence involving utilisation of p-coumaric acid with late generation of an intermediate catechol moiety in the right phenylpropanoid unit.

Rainfall partitioning and related hydrochemical fluxes in a diverse and in a mono specific (Phenakospermum guyannense) secondary vegetation stand in eastern Amazonia.

Rainfall partitioning into throughfall and stemflow was studied in a diverse and in a mono specific stand of secondary vegetation in Eastern Amazonia. The nutrient concentrations in the water were analysed in order to quantify the related hydrochemical fluxes. Secondary vegetation forms the fallow in the local shifting cultivation system and is usually dominated by shrubs and trees. Phenakospermum guyannense (Strelitziaceae), a banana-like herb, is one of the predominant non-woody species. The study was conducted during an 18-month period in a 2.5-year-old relatively species-rich stand and a 10-year-old stand dominated by P. guyannense. In a year with 1956 mm of rainfall 65% (1281 mm) of this quantity reached the soil as throughfall in the diverse stand and 38% (743 mm) in the mono specific stand. Stemflow was estimated to be 23% and 41% respectively. P. guyannense and Banara guianensis (Flacourtiaceae), a tree species, were causing these high funnelling effects. In the young diverse stand B. guianensis had a stemflow of more than 200 l year-1 and P. guyannense had a median flux of 77 l year-1 per pseudostem. In the older stand the taller plants of P.␣guyannense collected 644 l year-1 per pseudostem on the median. The reason for these high values could be the banana-like growth form of P. guyannense and the crown morphology of B. guianensis, which has inclined branches. The low proportion of throughfall and the high stemflow values differ from all previous studies in Amazonian primary forests. The proximity to the Atlantic Ocean strongly influenced the nutrient fluxes via rainfall at our study site. This becomes obvious from the high Na and Cl fluxes with rainfall (19.7 kg Na ha-1 year-1, 37.2 kg Cl ha-1 year-1) which were approximately equal to the Na and Cl fluxes with the sum of throughfall and stemflow for both stands. K fluxes in throughfall and stemflow in both stands were higher than in rainfall by a factor of 8. The high K enrichment during the crown passage is assumed to be caused by a␣high K concentration in the leaf tissue resulting in enhanced leaching from the leaves. In months with low␣rainfall the concentrations of Ca, Mg, S and Cl in throughfall of the diverse stand were significantly higher than in months with high rainfall. This was mainly due to vegetation burns in the dry period, which resulted in ash deposition on the canopy and subsequent wash-off and solution of ash particles.

[Morphologic findings in dilated cardiomyopathy and their relation to hemodynamics and catecholamine concentrations in the plasma and myocardium]. / Morphologische Befunde bei der dilatativen Kardiomyopathie und ihre Beziehung zur Hämodynamik und zu den Katecholaminkonzentrationen im Plasma und Myokard.

In 72 patients with dilated cardiomyopathy the degree of morphological alterations were studied by transvenous endomyocardial biopsy. These findings were correlated to the clinical status, left ventricular ejection fraction, and to the catecholamine concentrations in plasma and myocardium. Muscle fiber diameter was negatively correlated to ejection fraction (r = -0.3, p = 0.02) and to the volume fraction of mitochondria (r = -0.32, p = 0.001). Between plasma norepinephrine concentration and ejection fraction a significant negative correlation was found (r = -0.37, p = 0.001). In contrast, myocardial norepinephrine concentration was positively correlated to ejection fraction (r = 0.25, p = 0.04). Between myocardial norepinephrine concentration and muscle fiber diameter a negative correlation was found (r = -0.46, p = 0.004). Patients with an EF of less than 30% and an EF of greater than 45% could be differentiated with an accuracy of 79%, when muscle fiber diameter, plasma norepinephrine concentration, and the density of capillary vessels were entered into a multi-variant analysis. In conclusion, dilated cardiomyopathy is associated with morphological alterations and alterations in plasma and myocardial catecholamine concentrations. Patients with highly reduced ventricular function could be best identified by the combined assessment of plasma catecholamine concentration, muscle fiber diameter, and density of capillary vessels.