Convergence chromatographic determination of camphor in the essential oil of Tanacetum parthenium L.

Feverfew (Tanacetum parthenium L., Asteraceae) is a perennial medicinal plant which has been used to alleviate the symptoms of migraine, headache and rheumatoid arthritis and possesses numerous pharmacological activities. An ultra‐high‐performance supercritical fluid chromatographic method (UHPSFC) was developed and validated in accordance with the International Conference on Harmonization guidelines in order to determine the camphor content of the volatile oil, which was accurate, precise, robust and selective. The method was validated for specificity, accuracy (100.2%), repeatability and intermediate precision, linearity (r² > 0.999), limit of detection (2.055 μg/mL), limit of quantification (6.228 μg/mL) and robustness. The common range of accuracy and linearity was between 0.125 and 1.000 mg/mL. Steam distillation was carried out in order to study the essential oil yield of three different T. parthenium L. samples originating from Hungarian medicinal herb collections. The camphor content of the essential oils from the aerial parts of feverfew samples from different origin was compared. Although the composition of the essential oil is well reported, a validated quantitative UHPSFC method for the determination of the constituents is presented herein for the first time.     

Correlation-induced spectral changes in tissues

We report experimental evidence of correlation-induced spectral changes in biological tissues. The overall spectral shift in our transmission measurements is to the red and the mean wavelength of the original spectrum is up 10% larger. These results indicate that the spectral changes due to elastic scattering are significant and likely to hinder all spectroscopic measurements based on the inelastic (i.e., emission and absorption) interaction between light and tissues. Thus, simultaneous morphology and spectral measurements are required for accurate measurements spectroscopic information.     

CnH2nCl+ ion formation in electron impact MS conditions: a theoretical study

The mass spectral fragmentation of different 1-chloroalkanes (of the 1-chlorohexane-1-chlorooctadecane series) has been investigated, quantifying the relative abundance of the fragment ions. The base peak is dominantly at m/z 91, 93 in each investigated case, although with the increasing chain length, its contribution to the total ion current exhibits some reduction. Among the possible fragmentation products, the five-membered chloronium containing ring is the most stable as measured by an isodesmic reaction, although the six-and seven-membered rings exhibit only slightly reduced stability. The most stable structure of the 1-chlorohexane radical cation has a hydrogen bonded structure with the involvement of chlorine and the H_C(δ), pre-forming the five-membered cationic ring. Accordingly, among the reactions leading to alkyl (or H) radical and a chloronium containing ring, this transition structure has the lowest energy, providing explanation for the experimental observations.     

Understanding compressive deformation in porous titanium

The aim of this study was to understand and compare the compression deformation behavior of porous metals with random and designed porosity. Direct observation, analysis and quantification of porosity parameters using microcomputed tomography (µCT) enabled the determination of relationship between porosity characteristics and compressive deformation of porous titanium. Porosity and pore size variations before and after deformation showed relatively uniform deformation in the sample with random porosity compared to designed porosity. Strong, continuous and regular arrangement of load-bearing sections in the designed porosity sample imparted higher Young's modulus and 0.2% proof strength than for the random porosity sample. The experimental results clearly showed the dependence of deformation behavior and mechanical properties on pore distribution and continuity of load-bearing cross-section.     

Nonlinear optical absorption properties of porphyrins confined in Nafion membrane

The nonlinear absorption (NLA) properties of five different types of porphyrins were studied using the Z-scan technique. The porphyrins under investigation were confined into Nafion column matrix membrane in order to protect them from possible degradation. The results of the experiments have indicated that all the porphyrins tested exhibited interesting NLA properties. The nonlinear absorption coefficients (β’s) were determined at different porphyrin concentrations by comparing the Z-scan data with the theoretical functions.     

Neutron activation analysis for provenance studies of archaeological ceramics

Neutron activation analysis was used for provenance studies of ceramics from the early middle ages (avar period). 14 trace elements and Fe were determined by multiisotope comparator method. Computerized mathematical statistical methods (cluster-, and similarity analysis) were used for grouping the samples according to the similarity of their trace element distributions.To the memory of János BÉRCZI.     

Thermal studies on N-substituted maleic acid amides

Eight N-substituted maleic acid monoamide derivatives were studied by DSC, TG (DTG) and IR techniques. The thermal studies revealed that the compounds containing a free carboxyl group start to decompose before melting, and the decomposition continues in the melt phase as the temperature is elevated. This was explained by the presence of dimers involving strong intermolecular hydrogen-bonds. This assumption concerning the structure was supported by the results of the IR spectroscopic studies.

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Zusammenfassung Mittels DSC, TG (DTG) und IR-Techniken wurden acht N-substituierte Maleinsäuremonoamidderivate untersucht. Die thermischen Untersuchungen zeigen, daß die Zersetzung von Verbindungen mit freier Carboxylgruppe schon vor dem Schmelzen beginnt und der Zersetzungsprozeß dann in der Schmelze bei Anheben der Temperatur fortgesetzt wird. Dies wurde mit der Existenz von Dimeren mit starken intermolekularen Wasserstoffbrückenbindungen erklärt. Diese Annahme zur Struktur wurde durch die Ergebnisse der IR-spektroskopischen Untersuchungen bekräftigt.

     

Oxazolinethiones and oxazolidinethiones for the first copper-catalyzed desulfurative cross-coupling reaction and first sonogashira applications

Cyclic thionocarbamates, namely chiral oxazolidinethiones (OZT) and aromatic oxazolinethiones (OXT), were involved, for the first time, in Sonogashira cross-coupling. A cooperative effect of two different copper (I) species-CuI and CuTC-accounts for this new copper-catalyzed desulfurative carbon-carbon cross-coupling reaction. This cooperative reactivity could also be extended to other copper (I) catalysts.