Raman Optical Activity: A Reliable Chiroptical Technique

Vibrational optical activity (VOA) is a research field in full expansion. The two main areas where VOA is used are the determination of absolute configurations and the investigation of the secondary and tertiary solution structures of biopolymers. Commercial instrumentation is available since some time for vibrational circular dichroism (VCD) and, more recently, also Raman optical activity (ROA). Here, we describe a recent instrumental implementation of forward scattering, advances in the computational interpretation of ROA, and the determination of the mechanistically important absolute configuration of (4E)-3,3-dimethyl-5-[(2R,3R)-3-methyloxiran-2-yl]pent-4-en-2-one (1)

Evaluation du risque hygiénique lié à l’utilisation de digestats liquides en Suisse

Le but de ce projet était la caractérisation de l’état hygiénique des digestats liquides provenant des installations de méthanisation en Suisse. Ceci en relation avec les intrants utilisés et les techniques de prétraitement, de méthanisation et de post-traitements employées. Trois campagne d’échantillonnage ont été réalisées: en hiver 2012-1013, au printemps et en été 2013. Lors de ce travail, diverses installations représentatives de méthanisation mésophiles et thermophiles ont été étudiées en détail. Les teneurs en salmonelles, en germes coliformes, en E. coli, en entérocoques et en Campylobacter des intrants ainsi que les digestats provenant des diverses étapes des processus ont été analysées. Les déchets verts ainsi que les contenus des panses sont les intrants contenant le plus de germes pathogènes. Le lait et les produits OESPA en contiennent par contre relativement peu. Une grande variabilité entre les produits d’une même catégorie d’intrants est toutefois observée. Les salmonelles n’ont pu être mises en évidence que dans peu d’intrants et en quantités modestes. Une présence plus importante de salmonelle dans les intrants OESPA n’a pas été observée. Aussi bien les germes coliformes que E. coli et les entérocoques ont été trouvés en concentration moyennes dans la plupart des intrants. Campylobacter spp. n’a pu être isolé d’aucun intrant. Les salmonelles et E. coli sont efficacement éliminés dans les installations thermophiles et n’étaient plus détectables dans les digestats. Les teneurs en entérocoques étaient significativement réduites par les traitements thermophiles, sans être toutefois complètement éliminés. Dans les installations mésophiles, le processus de traitement n’a qu’une influence mineure sur les germes étudiés. Les quantités de E. coli ont été réduites, mais des quantités notables de ce germe ont été retrouvées dans les digestats. Il faut souligner qu’une multiplication des germes étudiés lors du traitement mésophiles n’a pas été observée. L’utilisation de digestat liquide frais ou stocké est à déconseiller dans des cultures consommées crues. De manière générale, une grande prudence est à observer lors d’utilisation de digestats mésophiles en maraîchage. Du point de vue hygiénique, les digestats liquides provenant d’installations thermophiles sont non problématiques, pour autant que la conduite de l’installation soit faite selon les règles de l’art. Pour les autres cultures, l’emploi de digestat mésophile est possible. Les mêmes recommandations d’utilisation que pour les lisiers sont à respecter

Spatial variations of nitrogen trace gas emissions from tropical mountain forests in Nyungwe, Rwanda

Globally, tropical forest soils represent the second largest source of N2O and NO. However, there is still considerable uncertainty on the spatial variability and soil properties controlling N trace gas emission. Therefore, we carried out an incubation experiment with soils from 31 locations in the Nyungwe tropical mountain forest in southwestern Rwanda. All soils were incubated at three different moisture levels (50, 70 and 90 % water filled pore space (WFPS)) at 17 °C. Nitrous oxide emission varied between 4.5 and 400 μg N m−2 h−1, while NO emission varied from 6.6 to 265 μg N m−2 h−1. Mean N2O emission at different moisture levels was 46.5 ± 11.1 (50 %WFPS), 71.7 ± 11.5 (70 %WFPS) and 98.8 ± 16.4 (90 %WFPS) μg N m−2 h−1, while mean NO emission was 69.3 ± 9.3 (50 %WFPS), 47.1 ± 5.8 (70 %WFPS) and 36.1 ± 4.2 (90 %WFPS) μg N m−2 h−1. The latter suggests that climate (i.e. dry vs. wet season) controls N2O and NO emissions. Positive correlations with soil carbon and nitrogen indicate a biological control over N2O and NO production. But interestingly N2O and NO emissions also showed a positive correlation with free iron and a negative correlation with soil pH (only N2O). The latter suggest that chemo-denitrification might, at least for N2O, be an important production pathway. In conclusion improved understanding and process based modeling of N trace gas emission from tropical forests will benefit from spatially explicit trace gas emission estimates linked to basic soil property data and differentiating between biological and chemical pathways for N trace gas formation

Spatial variations of nitrogen trace gas emissions from tropical mountain forests in Nyungwe, Rwanda [Discussion paper]

Globally, tropical forest soils represent the second largest source of N2O and NO. However, there is still considerable uncertainty on the spatial variability and soil properties controlling N trace gas emission. To investigate how soil properties affect N2O and NO emission, we carried out an incubation experiment with soils from 31 locations in the Nyungwe tropical mountain forest in southwestern Rwanda. All soils were incubated at three different moisture levels (50, 70 and 90% water filled pore space (WFPS)) at 17 °C. Nitrous oxide emission varied between 4.5 and 400 μg N m−2 h−1, while NO emission varied from 6.6 to 265 μg N m−2 h−1. Mean N2O emission at different moisture levels was 46.5 ± 11.1 (50% WFPS), 71.7 ± 11.5 (70% WFPS) and 98.8 ± 16.4 (90% WFPS) μg N m−2 h−1, while mean NO emission was 69.3 ± 9.3 (50% WFPS), 47.1 ± 5.8 (70% WFPS) and 36.1 ± 4.2 (90% WFPS) μg N m−2 h−1. The latter suggests that climate (i.e. dry vs. wet season) controls N2O and NO emissions. Positive correlations with soil carbon and nitrogen indicate a biological control over N2O and NO production. But interestingly N2O and NO emissions also showed a negative correlation (only N2O) with soil pH and a positive correlation with free iron. The latter suggest that chemo-denitrification might, at least for N2O, be an important production pathway. In conclusion improved understanding and process based modeling of N trace gas emission from tropical forests will not only benefit from better spatial explicit trace gas emission and basic soil property monitoring, but also by differentiating between biological and chemical pathways for N trace gas formation

Authentication of the botanical origin of honey using profiles of classical measurands and discriminant analysis

The potential of physical and chemical measurands for the determination of the botanical origin of honey by using both the classical profiling approach and chemometrics was evaluated for the authentication of ten unifloral (acacia, rhododendron, chestnut, dandelion, heather, lime, rape, fir honeydew, metcalfa honeydew) and polyfloral honey types (in total n = 693 samples). The classical approach using a profile for the determination of the botanical origin of honey revealed that the physical and chemical measurands alone do not allow a reliable determination. Pollen analysis is therefore essential for discrimination between unifloral and polyfloral honeys. However, chemometric evaluation of the physical and chemical data by linear discriminant analysis allowed reliable authentication with neither specialized expertise nor pollen or sensory analysis. The error rates calculated by Bayes' theorem ranged from 1.1% (rape and lime honeys) up to 9.9 % (acacia honey

Peritoneal dialysis in children after cardiopulmonary bypass

AbstractObjective: We reviewed 5 years' experience with peritoneal dialysis in children with acute renal failure after cardiac operations. We hypothesized that peritoneal dialysis is safe and effective in children with low-output cardiac failure after cardiac operations. Results: Mortality in these patients with renal failure (n = 32) was 46.9%. Fluid removed by peritoneal dialysis was 48 ± 28 ml/kg per 24 hours. Most complications of peritoneal dialysis were minor, hyperglycemia being the most frequent (53.1%). Peritoneal infection was suspected in 25%. Bowel perforation developed in two patients. None of the complications required early termination of dialysis. Hemodynamics and pulmonary function improved continuously during the study period. Conclusion: The early institution of peritoneal dialysis in acute renal failure and low cardiac output after cardiac operations not only removes fluid, thus easing fluid restriction, but may also improve cardiopulmonary function(J Thorac Cardiovasc Surg 1997;113:64-70

Quantitative analysis of physical and chemical measurands in honey by mid-infrared spectrometry

Fourier transform infrared spectroscopy (FT-IR) was used to determine 20 different measurands in honey. The reference values for 144 honey samples of different botanical origin were determined by classical physical and chemical methods. Partial least squares regression was used to develop the calibration models for the measurands studied. They were validated using independent samples and proved satisfying accuracies for the determination of water (R 2=0.99), glucose (0.94), fructose (0.84), sucrose (0.91), melezitose (0.98) and monosaccharide content (0.82) as well as fructose/glucose ratio (0.98), glucose/water ratio (0.94), electrical conductivity (0.98), pH-value (0.87) and free acidity (0.96). The prediction accuracy for hydroxymethylfurfural, proline and the minor sugars maltose, turanose, erlose, trehalose, isomaltose and kojibiose was rather poor. The results demonstrate that mid-infrared spectrometry is a valuable, rapid and non-destructive tool for the quantitative analysis of the most important measurands in hone

Beispiel für die Evolution der Synthese eines Entwicklungsproduktes: Herstellung des als 5 HT2C/2B-Receptor-Antagonisten wirksamen Indolo-naphthyridin-Derivates SDZ SER-082 in enantiomerenreiner Form

cis-4,5,7a,8,9,10,11,11a-Octahydro-7H-10-methylindolo[1,7-bc][2,6]naphthyridine (rac-4) (SDZ SER-082) is a selective and potent 5-HT2C/2B receptor antagonist, exerting weak affinity towards the 5-HT2A receptor site. The compound 4 was found to be a potential development candidate in several CNS indications. The key step in the initial synthesis was the photocyclization of the indolyl tetrahydropyridino-carbamic acid ethyl ester 1 to afford the cis/trans-naphthyridine 2/3. This process turned out to be inefficient for a scale-up. Three alternative synthetic routes A, B and C are discussed: The 'Imino-Diels-Alder' reaction applying indoline/formaldehyde/cyclopentadiene (route A) and the intramolecular Heck cyclization of 7-bromo-2,3-dihydro-1-[(1,2,5,6-tetrahydro-1-methyl-4-pyridyl)-carbonyl]-1H -indole (10) (route B) were surpassed in their synthetic efficiency by the Friedel-Crafts cyclization of 4-(2,3-dihydroindole-1-carbonyl)-1-methylpiperidin-3-one (16) (route C), followed by reduction to give rise to the racemic naphthyridine rac-4. It was subjected to resolution by applying a kg scale repetitive chromatography on a chiral stationary phase to give (+)-(7aS,11aR)-4 in over 90% yield and 99.9% enantiomeric purity