Radu Claudiu Fierascu

Archaeometallurgical Characterization of Numismatic Artifacts

The discovery of metals and alloys greatly contributed to the development of human civilizations; their role in shaping history is recognized by the scientific community even through the denomination of some archaeological periods (Copper Age, Bronze Age, and Iron Age). Archaeometallurgy appeared from the application of usually non destructive analytical techniques for the characterization of cultural heritage objects, with emphasis on metal artifacts. This article presents a case study regarding the application of fast and non-destructive methods (energy dispersive X-ray fluorescence and metallurgical microscopy) for the characterization of selected numismatic artifacts, thus obtaining information regarding their composition, authenticity, and state of preservation.

The miscibility estimation of some nanocomposites based on starch

Abstract Based on the FTIR spectral changes, the miscibility of some nanocomposites based on starch, polyvinyl alcohol and treated multilayered silicate, was qualitatively estimated. The FTIR spectroscopy provide evident gross/small spectral changes as well as appreciable spectral shifts mainly in those spectral range that defines hydroxyl O-H vibrations (3600- 3000 cm-1 ), water absorbtion (1800 - 1500 cm-1) , the morphological order degree and the interaction with multilayered silicate and (1192 - 950 cm-1). Based on the observed spectral modifications it can be estimate that high miscibility do exist between the components of the studied nanocomposites.

Thermal and mineralogical investigations of iron archaeological materials

In Covasna area from Romania, some heterogeneous metallurgical waste (slag) has been identified by archaeological excavations. This paper presents the analytical investigations of such an iron material, performed by inductively coupled plasma atomic emission spectrometry, energy dispersive X-ray fluorescence, X-ray diffraction and thermal analyses. From mineralogical point of view, the samples collected from the artefact are dominated by fayalite and almandine. Also, the slag has an iron-dominated composition, with magnetite, tridymite and quartz, too. Meanwhile, the ratios SiO2/Al2O3 and K2O/MgO are rather low (1.2–2), these being further proof for assigning the sample to a slag one. Because CaO, MgO, and K2O have low concentrations, it may be concluded that another material has been used to melt the mineral than the usually used wood and coal, most probably charcoal. The presence of vanadium is a proof of iron production from magnetite ore or hematite. Glass factor (G factor) of the monolithic samples has low values, corresponding to almandine–fayalite–tridymite–glass composite. The performed thermal analyses materialized into valuable information regarding the composition of the analysed materials.

Nanotechnology applied in archaeometry: restoration and conservation

The preservation of the cultural heritage is important for all countries, as this is a reminder of what they were once, being the most important element of identity in these modern days. The different directions and ways in which these processes are realized depend on the particular stage of development of science and technology, welfare of society, and encountered dangers of this identity. Very important objects of cultural heritage are material objects and objects of art produced by all communities. The study of nanostructured materials is considered an emerging field for the next years. To advance the field of preservation of cultural heritage science and nanostructured materials there is a continuous interdisciplinary collaboration between material science specialists and preservationists. In this work we present a complex study on the synthesis and the application of nanomaterials for the restoration and conservation of different artifacts.

Bacterial Nanocellulose from Side-Streams of Kombucha Beverages Production: Preparation and Physical-Chemical Properties

We focused on preparing cellulose nanofibrils by purification, separation, and mechanical treatment of Kombucha membranes (KM) resulted as secondary product from beverage production by fermentation of tea broth with symbiotic culture of bacteria and yeast (SCOBY). We purified KM using two alkaline solutions, 1 and 4 M NaOH, which afterwards were subjected to various mechanical treatments. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) were employed to evaluate the purification degree, the size and aspect of cellulose fibrils after each treatment step, the physical-chemical properties of intermediary and final product, and for comparison with micro-crystalline cellulose from wooden sources. We determined that 1 M NaOH solution leads to approx. 85% purification, while a higher concentration assures almost 97% impurities removal. XRD analysis evidenced an increase in crystallinity from 37% to 87% after purification, the characteristic diffractograms of Iα and Iβ cellulose allomorphs, and a further decrease in crystallinity to 46% after microfluidization, fact correlated with a drastically decrease in fibrils’ size. FTIR analysis evidenced the appearance of new chain ends by specific transmission bands at 2941 and 2843 cm−1.

Phyto-mediated metallic nano-architectures via Melissa officinalis L. : synthesis, characterization and biological properties

The development of methods for obtaining new materials with antimicrobial properties, based on green chemistry principles has been a target of research over the past few years. The present paper describes the phyto-mediated synthesis of metallic nano-architectures (gold and silver) via an ethanolic extract of Melissa officinalis L. (obtained by accelerated solvent extraction). Different analytic methods were applied for the evaluation of the extract composition, as well as for the characterization of the phyto-synthesized materials. The cytogenotoxicity of the synthesized materials was evaluated by Allium cepa assay, while the antimicrobial activity was examined by applying both qualitative and quantitative methods. The results demonstrate the synthesis of silver nanoparticles (average diameter 13 nm) and gold nanoparticles (diameter of ca. 10 nm); the bi-metallic nanoparticles proved to have a core-shell flower-like structure, composed of smaller particles (ca. 8 nm). The Ag nanoparticles were found not active on nuclear DNA damage. The Au nanoparticles appeared nucleoprotective, but were aggressive in generating clastogenic aberrations in A. cepa root meristematic cells. Results of the antimicrobial assays show that silver nanoparticles were active against most of the tested strains, as the lowest MIC value being obtained against B. cereus (approx. 0.0015 mM).

Spectroscopic study and catalytic activity for H2O2 decomposition of new zeolite-porphyrin systems

In this paper, some new catalytic systems—a metallic complex of 5,10,15,20-tetra-p-tolyl-porphyrin (TTP) with Fe [ClFe(III)TTP] entrapped into a natural zeolite (clinoptilolite) and into two synthetic zeolites (X-71, HZSM-5) were synthesized and characterized by energy-dispersive X-ray fluorescence (EDXRF), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, thermal analyses (TGA/SDTA) and tested subsequently as catalysts in the hydrogen peroxide decomposition reaction. The metalloporphyrin ClFe(III)TTP used was adsorbed in different proportions on the zeolite matrix. It is entrapped into The X-71 zeolite (due to its higher pore size), and adsorbed onto the other zeolites: HZSM-5 and clinoptilolite. The catalytic activities of the synthesized systems were discussed from kinetic and mechanistic aspects points of view. This paper also evidenced the generation of oxo-dimers of porphyrin during the catalytic reaction, this aspect being valuable for ClFe(III)TTP. The study of the catalytic activities of the synthesized systems leads us to the proposal of an adequate mechanism for the degradation of hydrogen peroxide in the presence of the synthesized catalysts. The most efficient catalyst according to our study is the ClFe(III)TTP/X-71 system.

Thermal and spectroscopic investigation of Romanian historical documents from the nineteenth and twentieth century

Abstract In 1958, at the end of the restoration and at re-consecration of St. Elijah Church in Pitesti (Romania), in an improvised archive, were discovered some historical documents (testaments, petitions, notices, etc.) going back to 1841. With the occasion of the re-consecration, another document was signed by the priests involved. All these documents were gathered together and transmitted from one priest to another, as the documents were considered valuable, presenting the habits of past generations and events of local historical importance. The present paper describes the characterization of eight paper documents selected from this collection, performed by thermal analysis, together with optical microscopy, Fourier transform infrared spectroscopy, inductively coupled plasma-atomic emission spectrometry, energy-dispersive X-ray fluorescence, X-ray diffraction as well as by the evaluation of the degree of polymerization and the colour change. The results revealed the type of fillers used (different from one sample to another); also, one of the samples presents a much higher content of lignin and hemicelluloses than the other samples. Thus, the conclusion that could be reached is that although all the documents originated from the same geographical area, the papers on which they are written have very different origin, in terms of composition and fillers used.

Phytochemical Profile and Biological Activities of Satureja hortensis L.: A Review of the Last Decade

Satureja hortensis L. (summer savory) is an annual herbaceous crop, native to Europe and in our days spread and used all over the world. Although its use as spice and medicinal plant is known since ancient times, peer-reviewed studies presenting the scientific data are scarce. The natural products obtained from summer savory (extracts and essential oil) are dominated by polyphenols and flavonoids, responsible for their antioxidant, antimicrobial, antiparasitic, pesticidal, anti-inflammatory, analgesic, hepatoprotective and anticancer properties, among others. The current study presents the progress made in the last decade regarding the potential applications of summer savory, being the first review study focused on S. hortensis, in the same time suggesting future research opportunities, as they appear from the properties of other Satureja species. The available data presenting the properties of summer savory represents a scientific support for application in industry, for developing “clean label” food products.

Phytosynthesis of gold and silver nanoparticles enhance in vitro antioxidant and mitostimulatory activity of Aconitum toxicum Reichenb. rhizomes alcoholic extracts

Extracts obtained from different plant species proved to be a valuable tool in various biomedical applications. In the same time, the phytosynthesis of noble metal nanoparticles represents an already well-established route for obtaining nanoparticles with biological activity. The present paper studies the antioxidant activity and the cytogenetic effects of the alcoholic extracts from rhizomes of Aconitum toxicum Rchb., before and after the phytosynthesis of gold and silver nanoparticles, on the meristematic root cells of Allium cepa L., and on the general mitotic index and the progression rate through the mitotic phases, respectively, as well as on the genetic material organized in chromosomes. The extracts were characterized in terms of total polyphenolics content (1.49% and, respectively, 2.29%) and aconitine content (by HPLC - 4.891 mg/L and, respectively, 18.211 mg/L), while the phytosynthesis of metallic nanoparticles was monitored by UV-Vis spectrometry, X-ray diffraction, X-ray fluorescence and electron microscopy. Both the extracts and the obtained nanoparticles were evaluated for antioxidant potential (the antioxidant activity ranging between 78% and 84.32%) and cytogenetic effects. The obtained results prove the phytosynthesis of AgNPs and AuNPs with dimensions ranging from 9 nm to 15 nm for AuNPs, respectively from 53 nm to 67 nm for AgNPs. The extracts obtained from rhizomes of A. toxicum Rchb. induced mitotic stress, as well as a series of nuclear and mitotic aberrations. The biosynthesis of AgNPs and AuNPs intensified the antioxidant and mitostimulatory activity of the extracts.