Diophantische Gleichungen und die universelle Eigenschaft Finslerscher Zahlen

Ohne Zusammenfassung     

Structures of xanthoviridicatin D and xanthoviridicatin G, metabolites of penicillium viridicatum: application of proton and carbon-13 NMR spectroscopy

The structures of xanthoviridicatin D and xanthoviridicatin G, toxic metabolites of $\text{Penicillium viridicatum}$, have been shown to be $\text{3}$ and $\text{4a}$, respectively by spectroscopic studies.     

Nonlinear 0–1 programming: I. Linearization techniques

Any real-valued nonlinear function in 0–1 variables can be rewritten as a multilinear function. We discuss classes of lower and upper bounding linear expressions for multilinear functions in 0–1 variables. For any multilinear inequality in 0–1 variables, we define an equivalent family of linear inequalities. This family contains the well-known system of generalized covering inequalities, as well as other linear equivalents of the multilinear inequality that are more compact, i.e., of smaller cardinality. In a companion paper [7]. we discuss dominance relations between various linear equivalents of a multilinear inequality, and describe a class of algorithms for multilinear 0–1 programming based on these results. Research supported by the National Science Foundation under grant ECS7902506 and by the Office of Naval Research under contract N00014-75-C-0621 NR 047-048.     

Kinetic study of the cure reaction of unsaturated polyester resins

The kinetics of the cure reaction of standard unsaturated polyester resin was investigated by utilizing the isothermal and dynamic techniques of differential scanning calorimetry (DSC). The kinetic parameters and heat of the copolymerization reaction were determined. A method is proposed for optimization of the curing and postcuring of a polyester resin composite.

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Zusammenfassung Die Kinetik der Aushärtung eines ungesättigten Standardpolyesterharzes wurde mittels isothermer und dynamischer DSC untersucht. Kinetische Parameter und die Reaktionswärmen der Kopolymerisation wurden bestimmt. Eine Methode zur Optimierung der Aushärtung und Nachhärtung von Polyesterharzverbundstoffen wird vorgeschlagen.

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This work was partly supported by the Chimica Fine e Secondaria project of the Italian C.N.R.     

Alkaloids and saponins in dietary supplements of blue cohosh (Caulophyllum thalictroides)

Preparations of blue cohosh (Caulophyllum thalictroides) have been used traditionally by Native Americans for medicinal purposes. Dietary supplements containing dried roots or extracts of blue cohosh rhizomes are available as dietary supplements. The safety and efficacy of these preparations have not been systematically evaluated. Recent studies indicate that ingestion of specific alkaloids in blue cohosh preparations can produce birth defects and neonatal heart failure. Blue cohosh also contains saponins, which may be responsible for uterine-stimulating effects. We determined the amounts of major alkaloids and saponins in preparations of blue cohosh by high-performance liquid chromatography (HPLC). Alkaloids and saponins were monitored with a photodiode array detector and an evaporative light-scattering detector, respectively. Profiles were compared with those of authenticated blue cohosh root extracts. Identities of the alkaloids and saponins were confirmed by HPLC/mass spectrometry and nuclear magnetic resonance spectrometry. Calculations based on the results of analyses of dietary supplements showed that maximum daily intake of alkaloids and saponins will vary with the form (e.g., root, liquid extract) and doses recommended in product labeling. Intakes may vary from < 1 to 75 mg/day for alkaloids and from about 9 to 420 mg/day for saponins.     

Preparative separation of di- and trisulfonated components of Quinoline Yellow using affinity-ligand pH-zone-refining counter-current chromatography

Four positionally isomeric 2-(2-quinolinyl)-1H-indene-1,3(2H)-dionedisulfonic acids (SA) and one triSA, components of the color additive Quinoline Yellow (QY, Color Index No. 47005), were isolated from the dye mixture by affinity-ligand pH-zone-refining counter-current chromatography (CCC) through complementary use of ion-exchange and ion-pair reagents as the ligand. The added ligands facilitated the partitioning of the very polar polysulfonated components into the organic stationary phase of the two-phase solvent systems that consisted of isoamyl alcohol–methyl tert-butyl ether–acetonitrile–water (3:5:1:7), (3:4:1:7) or (3:1:1:5). Thus, separation of a 5-g portion of QY using sulfuric acid as the retainer and dodecylamine as the ligand (an ion-exchange reagent, 20% in the stationary phase), resulted in 1.21 g of 6′,5-diSA and 1.69 g of 6′,8′,5-triSA, both of over 99% purity. A minor component, 8′,4-diSA, not previously reported was also obtained (4.8 mg of over 94% purity) through a similar separation of a different batch of QY using hydrochloric acid as the retainer and 10% dodecylamine as the ligand in the stationary phase. Two components that co-eluted (0.55 g) in the 5 g separation were separated when trifluoroacetic acid was used as the retainer and tetrabutylammonium hydroxide (an ion-pair reagent) as the ligand. The separation resulted in 20.7 mg of 6′,4-diSA, not previously reported, and 111.8 mg of 8′,5-diSA, both of over 98% purity. The isolated compounds were characterized by high-resolution mass spectrometry and proton nuclear magnetic resonance with correlated spectroscopy assignments.     

The stabilization of archaeological iron objects: Mössbauer and XRD studies

Archaeological iron objects that were buried in the ground for long times often corrode rapidly once they have been excavated. We have used Mössbauer spectroscopy and X-ray diffraction to elucidate some specific problems of the corrosion of such objects and gain insights that may help to improve the methods of conservation.     

Development and evaluation of microencapsulated sunscreen

The aim of the present study was to carry out stability tests and in vitro sun protection factor (SPF) evaluations of formulations containing free or microencapsulated chemical sun filters to improve their use. To this end, three formulations were developed and subjected to stability studies. The most stable formulation was chosen as a vehicle for free and microencapsulated chemical sun filters, and subjected to further stability studies and in vitro SPF assays. The SPF values were approximately 12 and 11 for formulations containing free and encapsulated sun filters, respectively, and both types were stable under stress. Chemical sun filters can be microencapsulated, which may aid in generating innovative sunscreen formulations.     

Online coupling of high‐performance liquid chromatography with surface‐enhanced Raman spectroscopy for the identification of historical dyes

High‐performance liquid chromatography (HPLC) is still, today, the technique of choice for the analysis of natural dyes in artistic objects and historical textiles, particularly in association with photodiode array (PDA) detection. In the last two decades, surface‐enhanced Raman spectroscopy (SERS) gained also increasing importance for these investigations thanks to its sensitivity and limited requirements in terms of sample quantity. In favor of SERS, its high specificity in molecular recognition typical of vibrational spectroscopy should be mentioned, whereas this non‐separative technique is obviously disadvantaged in the analyses of mixed chromophores, as is often the case of many natural dyes and also of tints obtained by the combined use of different colorants. An optimized experimental setup combining the two techniques, HPLC‐PDA and SERS, is proposed in the present work, allowing online SERS detection of different dyeing compounds eluted from the HPLC column. Examples are presented concerning some of the colorants most widely used in history, such as morin and luteolin for yellow dyes, alizarin, purpurin, laccaic, kermesic, and carminic acids for red ones, and indigotin for blue tints. Copyright © 2016 John Wiley & Sons, Ltd.