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Ślady krwi na Całunie Turyńskim : analiza materiałowa od mikro do nanoskali

Jaworski J. S.

Wiadomości Chemiczne

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2018

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[Z] 72, 1-2

61--80

EN

Modern experimental methods of materials science including optical and electron microscopy (SEM, ESEM, HRTEM), X-ray spectroscopy (EDX, WAXS), Raman and FTIR spectroscopy used in investigations of structures of new materials can be also successfully applied for analysis of archeological, cultural heritage and art objects. An interesting example of such analyses are investigations of microscopic fibers and particles taken previously from areas attributed to the blood on the Shroud of Turin. Detailed analyses performed by a number of research groups published in 2015–2017 are reviewed. They confirmed previous hypothesis on blood authenticity and discovered new evidences indicated a violence hidden behind the death. In particular, the presence of old red blood cells was documented by Lucotte [20], of bile pigment biliverdin by Laude and Fanti [28], of iron oxide cores of ferritin bounded to nanoparticles of creatinine by Carlino et al. [31]. The last result is typical for patients with severe polytrauma indicating at the unexpected nonoscopic level a tremendous suffering of the victim wrapped in the Shroud of Turin. Bigger particles of mineral pigments: ochre (iron oxide) and vermillion (mercury sulfide) were also found but they can be easily distinguished form blood particles using environmental electron microscopy ESEM with the back-scattered electrons detector [24]. The statistical analysis of a sample composition made by Fanti and Zagotto [24] indicated that 90–95% of the observed volume corresponds to the blood and only remainder represents inorganic pigments. Thus, it was proposed [24] that the original human blood on Shroud stains was much later reinforced by red pigments using a color dust without any binder and this hypothesis can easily explain controversies between previous results of different researches.

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Mechanizm elektrodowego osadzania i rozpuszczania magnezu w rozpuszczalnikach niewodnych

Jaworski J.S.

Wiadomości Chemiczne

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2007

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[Z] 61, 9-10

687-705

EN

Reversible deposition of magnesium on electrodes and its anodic dissolution in non-aqueous solvents are possible only from particular electrolytes, like ethereal solutions of Grignard reagents or recently elaborated complexes of alkylaluminum chlorides with dialkylmagnesium. The above processes are important in developing rechargeable magnesium batteries but can also help organic chemists for deeper understanding of the formation of Grignard reagents in classic reactions. Magnesium deposition from solutions of Grignard reagents has been known for more than 80 years but repeated efforts to explain the reason of reversibility and find other suitable electrolytes were unsuccessful for a long time. Recently, a sig-nificant progress was achieved due to the application of modern spectroscopic methods combined with electrochemical measurements. These results are presented. They include a finding of Liebenow [27, 28] that the magnesium dissolution strongly depends on the morphology of depositions and conclusions from reports of Aurbach and coworkers [12, 32-42] which explained in detail characteristics of the magnesium surface in a contact with different electrolytes, the role of adsorption of ions and radicals in electrode processes and the nature of electro-active species in various solutions. Finally, the proposed electrode mechanism of the magnesium deposition and dissolution from different electrolytes, shown in Scheme 2 and reactions (12)-(16), is presented.

3

Kinetyka rozrywania wiązania w aromatycznych anionorodnikach oraz ich tworzenia

Jaworski J.S.

Wiadomości Chemiczne

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1998

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[Z] 52, 5-6

367-382

EN

The theoretical model proposed by Savéant [10] for the kinetics of the cleavage of aromatic anion radicals containing potential leaving groups and of their formation from aryl radicals and nucleophiles (essential steps of the SRN1 mechanism, shown in the Scheme 1) is presented. In that model the bond cleavage in anion radicals is viewed as an intramolecular dissociative one electron transfer and the reverse reaction as an associative single-electron transfer. It leads to the quadratic relationship of the activation barrier DG= and the reaction driving force DG0 (eq. (9)), similar to the classic equation of the Marcus theory for the outer-sphere electron transfer. Experimental consequences of the Savéant model are also reviewed. They include the relationship between the cleavage rate constants k4 and the formal potentials of the radical anion formation E0RX?RX for the series of aryl chlorides and bromided in DMF (Fig. 3), solvent effects on the k4 values (Chapter 4) and the effect of substituents (Chapter 5). In particula, it was shown that the solvent effect on the thermodynamic contribution to the activation free-energy causes the increase of the cleavage rate constant for chloroanthracene radical anions with the solvent acceptor number (Fig. 4). However, for the dissociationof the C-Cl bond in radical anions of 4-chlorobenzophenone the solvent effect on the intrinsic activation barrier DG0=, given by eqs (13) and (14), is dominant and the intrinsic rate constant depends (Fig.5) on the solvent Pekar factor (1/eop -1/e0). The use of the Hammett equation to the cleavage rate constants is also discussed; it works in the case when the thermodynamic contribution to the activation barrier (eq. (12)) strongly depends on a substituent (Fig.6). All the reviewed experimental data on the kinetics of the bond cleavage and the formation of radical anions can be rationalized on the basis of the Savéant model.