STUDIA CHEMIA - Issue no.4 / 2018 - Table of contents

The article discloses the AMS (accelerator mass spectrometry) radiocarbon dating results of the pedunculate oak of Botoşana. Four wood samples were extracted from its trunk. Five segments extracted from these samples were analyzed by AMS radiocarbon. Their radiocarbon dates were found to be between 161 ± 21 BP and 260 ± 20 BP. These values correspond to calibrated ages of 235 – 365 years. The dating results extrapolated to the geometric center of the trunk indicate an age of 645 ± 50 years for the oak of Botoşana.

Keywords: AMS radiocarbon dating, Quercus robur, dendrochronology, age determination

Two series of magnetic nanopowders were synthesized at room temperature starting from a mixture of iron II and III precursors, FeSO4 and FeCl3, respectively. Precipitation agents, as KOH and NaOH were used. While the concentration of the added ferrous and ferric solutions ranged between 0.1 M and 0.0125 M, the hydroxide solution concentration was maintained constant (1 M). TEM images of the samples showed that the particles shape changes from quasi spherical to spherical. For both series the crystallite size decreases with iron concentration, from 9 to 2 nm for KOH series and from 10 to 3 nm for NaOH series. Moessbauer Spectroscopy was signaling only Fe3+ in the final spinel product. BET measurements revealed the material mesoporosity and fractal structure of maghemite nanoparticles that explain the unusual high surface area, ~240 m2/g. All the samples actually exhibit superparamagnetic behavior at room temperature with saturation magnetization up to 73 emu/g value closed to those of bulk maghemite.

Keywords: iron oxide nanoparticles, co-precipitation, fractal surface, Moessbauer Spectroscopy

Thiolactic acid, containing a reactive sulphydryl group, has been shown to easily reduce Cr(VI) and yield disulfide as oxidation product. The reaction was studied by the use of spectrophotometry. The spectral data as well as the kinetic information showed distinct evidence of the formation of an Sbonded Cr(VI)-thiolactate intermediate that was subsequently followed by a somewhat slower, bimolecular redox process leading to the formation of the final products. The rate laws for these two stages have been determined, showing a complex dependence on substrate and hydrogen ion concentration. Small experimental Arrhenius activation energies for the two successive steps were also obtained. The involvement of paramagnetic Cr(V) species and that of some organic free radicals were evidenced by ESR and, the latter, also by initialization of polymerization. A reaction mechanism has been proposed, that leads to a rate law in convincing agreement with the experimental one.

Keywords: kinetics, redox, chromium VI, thiolactic acid

A novel series of transitional metal complexes of Cu(II), Co(II), Ni(II), Zn(II) and Fe(II) with N-modified glycine as ligand provide from phenylserinol were synthesized and characterized via elemental analysis, MS, IR, UV-VIS thermogravimetric analysis and ESR. The thermal stability of the ligand and synthesized complexes was discussed in the 20-1000oC temperature range. The results indicate that the organic compound acts as a bidentate ligand, its coordination involving the carboxylate oxygen and the nitrogen atom belonging to the amino group of the glycine fragment. The shape of ESR spectrum for cooper complex at room temperature suggest an axial symmetry around the metallic ions (gII=2.427, g┴=2.063).

Keywords: glycine, transition metal complexes, thermal behavior, spectroscopic studies.

Our present approach is dealing with comparative cytotoxicity assays performed with a porphyrin base, substituted with methoxy-inductive donor substituents in the meso position, namely: 5,10,15,20-tetrakis-(pmethoxy- phenyl porphyrin (TMeOPP) and with its Zn(II), Co(II) and Cu(II) complexes (Figure 1). The cytotoxicity evaluation was performed using human (HeLa, 8 MGBA, Lep-3) and bovine (MDBK) cell lines as model systems. The influence of the compounds on cell viability and proliferation was studied by (thiazolyl blue tetrazolium bromide) MTT test and further discussed taking into consideration the main optical and aggregation properties of the free porphyrin and its different metal complexes.

Keywords: Zn(II), Co(II) and Cu(II)-metalloporphyrins, cytotoxicity evaluation, UV-vis spectroscopy, STEM microscopy, MTT test.

Phenylketonuria (PKU) is a genetic disorder which can lead to serious long-term complications in children, including intellectual impairment. The cerebral damage can be largely eliminated if hyperphenilalaninemia (HPA) and PKU is detected by newborn screening and the dietary treatment (started no later than 10 days after birth), brings within 15 days the blood Phe level in the ranges 2 - 6 mg/dL (or equivalently 120 - 360 μmol/L). Consequently, the measurement of plasma Phe level in children with PKU is of utmost importance. We present here in detail two methods for determination of plasma Phe concentrations in children with HPA (detected by newborn screening) or suspected to have PKU based on clinical symptoms. The first method, involving two-dimensional thin-layer chromatography (2D - TLC) on micro scale chromatograms, allows the identification of patients with PKU. However, the quantitation of plasma Phe concentration by the 2D - TLC video-densitometric method is only semiquantitative, because is accompanied by large errors. In contrast, the high performance liquid chromatography determination of the plasma Phe level is fast, very sensitive and higly accurate. Both methods are rather cheap and reliable, suitable for use in countries that cannot afford more expensive procedures for diagnosis and monitoring of PKU.

Keywords: amino acids (AA), phenylalanine (Phe), phenylketonuria (PKU), hyperphenylalaninemia (HPA), high performance liquid chromatography (HPLC), thin layer chromatography (TLC), phenylalanine hydroxylase (PAH).

We have synthetized silver nanoparticles capped with: citrate, mercaptosuccinic acid, and thioctic acid respectively. Each of the obtained nanoparticles were characterized by means of: UV-Vis and ATR-FT-IR spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM) and were found to be spherical in shape and aqueous stable

Keywords: silver nanoparticles, capping agents, citrate, mercaptosuccinic acid, thioctic acid

Type 1 diabetes mellitus (T1DM) is caused by the insulin deficiency resulting from the progressive destruction of pancreatic β cells. Thiazolidine-2,4-diones (TZDs) activate the peroxisome proliferator-activated receptor-γ (PPARγ) and enhance the actions of insulin. 5-((6-methyl-4-oxo-4Hchromen- 3-yl)methylene)-3-(2-(4-nitrophenyl)-2-oxoethyl)-thiazolidine-2,4-dione (TZDd) is a heterocyclic derivative synthesized in our laboratory. The purpose of this study was to examine whether TZDd has hypoglycemic and antioxidant effects in diabetic rats. Its effects were compared with those of quercetin (Que), a potent antioxidant, and with pioglitazone (Pio), a well-known antidiabetic drug. Type 1 DM was induced in Wistar rats by the intraperitoneal administration of streptozotocin (STZ) (60 mg/kg). The non-diabetic and diabetic rats were treated with Que (30 mg/kg/day), pioglitazone (30 mg/kg/day), or TZDd (30 mg/kg/day), for 5 weeks. The serum levels of malondialdehyde (MDA) and protein carbonyl (PC) groups, and the superoxide dismutase (SOD) and catalase (CAT) activities in the blood were then assessed. The results indicated that the TZDd decreased the blood oxidative stress parameters in the treated diabetic rats, compared to Que and pioglitazone. In conclusion, the hypoglycemic and antioxidant effects of TZDd in diabetic rats, suggest its therapeutic properties for the clinical treatment of T1DM.

Keywords: diabetes mellitus; oxidative stress; quercetin; pioglitazone, thiazolidine-2,4-dione

The ICP-MS technique was used to determine elemental composition (Pb, Sr, Cd, Ni, Co, Cu, Ni, Hg, As, Cr and Mn) of wines (Muscat Ottonel, Fetească Albă, Fetească Regală, Fetească Neagră, Merlot and Cabernet Sauvignon) wines produced in 2015, 2016 and 2017 from Bujoru, Smulti and Oancea wine-growing centers from Dealu Bujorului Vineyard. For all tested wine samples, the toxic metals contents were found in quantities below the limits established by legislation. The average data shows that the red wines contain highest concentration of Cd (0.17 μg/L), while the content of Cd in white wines are 0.11 μg/L. The concentration of U was 0.25 μg/L in red wines and 0.24 μg/L in white wines, while the concentration of Hg was 0.24 μg/L in red wines and 0.20 μg/L in white wines. The mean contents of Ni, Cr and Mn were 312.32 μg/L, 526.19±2.63 μg/L and 0.59±0.08mg/L, respectively. The concentration for Cu ranged from 0.45±0.10 mg/L to 0.90±0.04 mg/L, the last value being close to the law limit (1 mg/L). The four samples [Merlot 0.82±0.07 mg/L Bujoru wine-growing center (2015), Feteasca Alba 0.83±0.05 mg/L Smulti wine-growing center (2015), Merlot 0.83±0.05 mg/L Smulti winegrowing center (2015) and Cabernet Sauvignon 0.83±0.08 mg/L Oancea winegrowing center (2015)] showed relatively high concentration of Cu. Reporting the obtained results [Cd average 0.13±0.02 μg/L (0.1mg/kg M.L.A. = Maximum Limit Allowed) Pb average 40.64±1.85 μg/L (0.15 mg/kg M.A.L); As average 11.87±1.37 μg/L (0.2 mg/kg M.A.L); Cu average 0.67±0.09 mg/L (1 mg/kg M.A.L) to national and international legislation we can say that the wine from Dealu Bujorului vineyard falls within the limits set by the law. The content of potentially toxic elements such as Cd, Pb, U, Hg, As, Cu, Ni, Cr and Mn are lower than values found in literature, highlighting the safety and quality of the analysed Romanian wines.

Keywords: Dealu Bujorului vineyard, elemental composition, geographical traceability, wine

Fresh rainbow trout fillets are very perishable food products. Therefore, they cannot be stored at refrigeration temperatures for a long period of time. High pressure processing (HPP) can improve the quality of the fillets through microbial load control. As a result of this, the shelf-life of the product is extended. However, some physicochemical changes can appear. The aim of this study was to assess the degree of protein denaturation in rainbow trout fillets treated with various levels of high pressure. The results showed that protein denaturation is definitely higher for the fillets treated with higher pressure levels, in the range of 400 MPa/3 min – 600 MPa/6 min and lower for the fillets treated with lower pressure levels, in the range of 100 MPa/3 min – 200 MPa/6 min. The use of lower pressure levels is beneficial to the structural quality preservation of the fillets, but less effective concerning the microbial inactivation. Maintaining a good structural and nutritional quality of the product is not very useful in this case, because it cannot be combined with other great advantages offered by the HPP tools, namely microbial control and spoilage decline. Therefore, further studies should focus on readjusting (e. g. minimizing) the holding time and other possible parameters, without lowering the high levels of pressure.

Keywords: high-pressure processing, microbial load, protein denaturation, rainbow trout fillets

The present study evaluates the characteristics and performances of plaster mortars for construction, with the addition of oxide waste resulted from the filling of metal statues. Several plaster mortars using 0 %, 5 %, 10 %, 15 % and 20 % wt. of waste in composition were prepared in the laboratory and the physical and mechanical characteristics were determined. The waste oxide composition is mainly formed of 61.26 % SiO2, 11.20 % Al2O3 and 23.50 % CaSO4. The consistency water is about 75 % for mortars without waste. With increasing the waste content in the mortar composition, the amount of water decreases at about 50 %. It was also determined the setting time for all plaster mortars without any setting time retarder. The initial setting time for the control mortar was 12 minutes and with increasing the waste percentage in the composition, the setting time increased proportionally, reaching 18 minutes for the sample with 20 % wt. waste. The flexural strength of 2.03 N/mm2 and compressive strength of 10.31 N/mm2 were obtained for the sample with the highest amount of waste (20 % wt.).

Keywords: oxide waste, plaster mortar, mechanical properties

Even if the mobile devices gain more popularity comparing to the desktop personal computers (DPCs), the last ones are still intensively used where highly computing or storage capabilities are required. Because the replacing rate of DPCs are very high, the amount of obsolete equipments is also huge, reclaiming adequate efficient and ecological recycling techniques. In this field, the main efforts are focused on the DPCs motherboards (DPCMBs) recycling because, even if they represent only 5 to 10% from the DPCs weight, they concentrate up to 80% from the recoverable value. By accounting the DPCMBs' traditional and incipient recycling technologies, it is obvious that none of them can solve alone the problem of this waste type. In this context, during the present work, the composition evolution of 10 DPCMBs released between 1998 and 2008 was evaluated and analyzed, the obtained results being used to design a feasible and eco-friendly combined strategy for integral DPCMBs recycling.

Keywords: Waste printed circuit boards, metals recovery, composition evolution, recycling strategy, eco-friendly process

Environmental data achieved with the Air Quality Monitoring Station in Dej city, Romania, reveal a normal state of particulate matter (PM) emissions below the standard limit in April and May 2017. These airborne particles contain a large amount of mineral fractions such as: quartz, calcite, clays (e.g., kaolinite and muscovite), and lepidocrocite. Their size varies in a wide range: from 1 to 200 μm for floating particles (FP) and from 1 to 10 μm for PM10 observed by optical microscopy and SEM. The in vivo testing shows the ability of PM10 to penetrate into the upper respiratory tract. Mineral fractions were found in nasal exudates. At a shorter exposure time (e.g., 1 minute), only PM10 particles were observed. Particles larger than PM10 were found in nasal exudates at prolonged exposure for up to 3 minutes.

Keywords: Floating particles, PM10, hazard

The main purpose of this study was an investigation of the chemical composition of essential oils obtained from Satureja cuneifolia Ten. and S. montana L. collected at the National park Lovćen, Montenegro. The qualitative and quantitative analysis of the essential oils, performed by GC/MS and GC/FID, indicated that the most abundant compound in S. cuneifolia essential oil was oxygenated monoterpene linalool (20.3%). Within the sesquiterpene compounds, trans-(E)-caryophyllene (6.1%), germacrene D (5.8%), nerolidol (5.2%) and spathulenol (5.0%) were present in relatively high quantities. Conversely, S. montana essential oil was abundant in monoterpenes, with p-cymene being the main constituent (16.6%). Besides, limonene (10.8%), thymol (6.5%), α-pinene (6.1%) and borneol (5.5%) were present in a high percentage. The results indicated that investigated Satureja species essential oils possessed different chemical composition, but both might represent an interesting resource of pharmacologically active compounds.

Keywords: Satureja cuneifolia; Satureja montana; essential oil; terpenes; Montenegro.

A natural zeolite of Kazakh origin, as well as its three different types of chemically modified versions, were assessed from the point of view of permanganate removal yield from aqueous solutions. Modification was carried out by means of di-dodecyl-dimethyl-ammonium bromide surfactant treatment type (1). Types (2) and (3) were treated prior to DDAB wth HCl or NaCl, respectively. All sorbents display broad ranges of particle size distribution. Modification of the natural form enhances the specific surface as well as the pore volume, yet influences not in the same way the sorption yield. The process is slow, however, short- and long-term effectiveness are affected by preparation procedures. The most promising yield is exhibited by the natural zeolite that was subject to a combined acid - surfactant treatment.