Untersuchung von Kaffee. Kaffeebestandteilen und Kaffeersatzstoffen

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Effect of the addition of sulfur compounds on the hydroformylation of 1-hexene catalyzed by rhodium systems

The effect of the addition of triphenylphosphine sulfide, thiophene, benzo[b]thiophene and dibenzo[b,d]thiophene on the hydroformylation of 1-hexene catalyzed by rhodium complexes RhH(CO)₄, RhH(CO)₂(PPh₃)₂ and RhH(CO)₂(diphos) was studied. The addition of these sulfur compounds did not affect the activity of non modified rhodium precatalysts, decreased the activity of the PPh₃-modified one and increased the activity of the diphos-modified ones, which is indicative of the sulfur tolerance of these precatalysts. The linear to branched ratio (l/b) varied from 0.5 to 3.4 for the non-modified precatalyst, and from 1.7 to 3.3 for the phosphine-modified ones.     

Hydrogenation of heteroaromatic nitrogen compounds catalyzed by rhodium and iridium systems containing diphosphine ligands

The systems prepared in situ by addition of two equivalents of diphosphine [1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane (dppb)] to M₂Cl₂(COE)₄ (M = Rh, Ir; COE = cyclooctene) showed to be efficient and regioselective precatalysts for the hydrogenation of quinoline, isoquinoline, 5,6- and 7,8-benzoquinoline and acridine, under mild reaction conditions (130°C and 4 atm H₂). The Rh systems showed to be more active than the corresponding Ir ones, except for the case of acridine, where an inversed tendency was observed (Ir > Rh).     

Analysis of salazinic, norstictic, and usnic acids in Xanthoparmelia chlorochroa by ultra-performance liquid chromatography/tandem mass spectrometry

The lichen species Xanthoparmelia chlorochroa is toxic when consumed by domestic sheep, cattle, and Rocky Mountain elk. Clinical signs exhibited by poisoned animals include red urine, ataxia, and muscular weakness that rapidly progresses to recumbency. Elk are unable to recover once becoming recumbent; however, most affected cattle can recover if offered suitable feed shortly following the onset of signs. At present, the pathogenesis and specific toxin(s) are unknown. As part of an effort to elucidate the proximate toxin, a method using ultra-performance LC coupled to MS/MS with negative-ion electrospray ionization has been developed to compare salazinic, norstictic, and usnic acid concentrations in X. chlorochroa collected from locales associated with lichen poisonings. Compounds were extracted from lichen samples with acetone and sonication. The stationary phase was a Waters Acquity UPLCTM BEH Ca18 (50 x 2.1 mm; 1.7 microm particle size) column. The mobile phase consisted of an acetonitrile-water gradient. The precision of the method was confirmed by an SD below 0.4% (n=9) for triplicate samples. LOD values were 200, 100, and 50 ng/mL for salazinic, norstictic, and usnic acids, respectively.     

Mehl, Teig, Backware

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Antitumor Potential of Annona muricata Linn. An Edible and Medicinal Plant in Mexico: In Vitro,In Vivo,and Toxicological Studies

Annona muricata (Am) is a plant used in traditional Mexican medicine to treat cancer. In this study, ethanol extracts of Am collected in Acapulco and Tecpan from Guerrero state were evaluated orally on Balb/c mice inoculated with 4T1 cells, for cytotoxic activity (CA) on 4T1 cells, in brine shrimp lethality assay (BSLA), and for acute oral toxicity in mice. In addition, ethanol extracts were subjected to high-performance liquid chromatography (HPLC) with diode array detection. Results showed that the extracts collected in December in Acapulco (AcDe) and Tecpan (TeDe) exhibited the most significant antitumor and cytotoxic activity. In the BSLA, the most important effect was observed in the extracts from Acapulco and Tecpan collected in June (AcJu) and August (TeAg), respectively. The samples from Acapulco (AcJu, and AcAg) and Tecpan (TeJu and TeAg) showed the highest toxicity. The analysis of the extracts, AcDe and TeDe, by HPLC revealed that flavonoids, rutin, narcissin, and nicotinflorin were the major components. These findings suggest that extracts from Am collected in Acapulco and Tecpan in the month of December may be an important source to obtain flavonoid glycosides with anticancer potential specifically against breast cancer. This also supports the use of Am to treat cancer in Mexican traditional medicine.     

Untersuchung von Kaffee und Kaffee-Ersatzstoffen

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Ein kapillaranalytischer Salizyls?urenachweis mittels Eisenchlorids

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The gravitational light shift and the Sachs-Wolfe effect

Using a 3+1 decomposition of spacetime, we derive a new formula to compute the gravitational light shifts as measured by two observers which are normal to the spacelike hypersurfaces defining the foliation. This formula is quite general and is also independent of the existence of Killing fields. Known examples are considered to illustrate the usefulness of the formula. In particular, we focus on the Sachs-Wolfe effect that arises in a perturbed Friedman-Robertson-Walker cosmology.