9 research outputs found
Heterotrophic leaching and its application in biohydrometallurgy
No full textWeb of Science108111045104
The Sonic Resonance Method and the Impulse Excitation Technique: A Comparison Study
No full textIn this study, resonant frequencies of flexurally vibrating samples were measured using the sonic resonant method (SRM) and the impulse excitation technique (IET) to assess the equivalency of these two methods. Samples were made from different materials and with two shapes (prism with rectangular cross-section and cylinder with circular cross-section). The mean values and standard deviations of the resonant frequencies were compared using the t-test and the F-test. The tests showed an equivalency of both methods in measuring resonant frequency. The differences between the values measured using SRM and IET were not significant. Graphically, the relationship between the resonant frequencies is a line with a slope of 0.9993 ≈ 1
A link between the p53 germ line polymorphisms and white blood cells apoptosis in lung cancer patients
No full textThe p53 protein acts as a checkpoint in the cell cycle, either preventing or initiating apoptosis. Since cancer is the unchecked proliferation of cells, p53s role is critical. Thus, we have sought a link between the p53 polymorphisms and apoptosis. Wild-type p53 tumor suppressor gene exhibits several common single nucleotide polymorphisms (SNP) both in coding and non-coding regions. We focused on two of them, the p53 BstUI SNP on the fourth exon, and the p53 MspI SNP on the sixth intron. We investigated a presence of these two polymorphisms in relation to apoptosis of white blood cells in lung cancer patients and healthy controls. We found that both the p53 BstUI and the p53 MspI homozygous genotypes A2/A2 were associated with significantly higher content of apoptotic white blood cells in comparison to relevant A2/A1 heterozygous genotypes (P < 0.001, 0.05) in lung cancer patients. These observations suggest that the p53 BstUI and the p53 MspI SNPs may play a certain role in p53 dependent apoptotic pathway
Solubilization of toxic metal mineral by the Aspergillus niger strain and oxalic acid
No full textThe objective of this study is solubilization of lead and arsenic from toxic metal mineral lead arsenate hydroxide - hydroxymimetite with oxalic acid and distilled water. Furthermore, the Aspergillus niger (A. niger) strain was applied for solubilization of lead and arsenic from hydroxy-mimetite. Oxalic acid was confirmed as the best leaching agent and was able to mobilize 96% of As and 1.49% of Pb. Also, the oxalic acid was capable of solubilizing inorganic Pb from crystalline compound and transforming it into the different organic Pb phase, which partially precipitated as lead oxalate Pb(C2O4). Our experimental studies bring insight into the biogeochemical cycles of the studied elements and have potential application in the bio-hydro-metallurgical processes for recovery of arsenic and lead from different materials (e. g. toxic metal minerals, mining ores, contaminated soil and sediment and other environmental area).Web of Science2182297228
Crystal-Chemical and Spectroscopic Study of Gem Sphalerite from Banská Štiavnica, Slovakia
No full textA complex crystal-chemical investigation based on spectroscopic methods, Electron MicroProbe Analysis (EMPA), and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was made on sphalerite samples from the Terézia and Rozália veins in the Banská Štiavnica ore district. The yellow (sample A) and olive-green sphalerite (C) are in association only with quartz; orange sphalerite (B) is associated with quartz and chalcopyrite; and black sphalerite (D) is associated with galena, chalcopyrite, quartz, and baryte. EMPA revealed that Cd and Fe are substituting for Zn with variable proportions; the Cd/Fe ratio decreases from 2.82–2.85 in the A sample to 0.42 in the D sample. LA-ICP-MS showed that, except Cd and Fe, only Mn has content above 20; Co and Cu vary between 2 and 17 ppm. The optical absorption spectra exhibit absorption between 644 and 740 nm with three smaller humps at 669–671, 698–702, and 732–743 nm, and weaker absorption bands at 858–894 nm in the NIR region, which can be all assigned to crystal-field transitions of Fe2+. The absorption edge starts at about 600 nm to the UV region. Minimal absorption is in the yellow-red part of the visible spectrum giving rise to yellowish-orange and orange-red colors. Absorption in the red region for olive-green sphalerite is more pronounced, explaining the shift to greenish hues. In black sphalerite, the absorption pattern is similar to the olive-green sphalerite, but the bands in the 644 to 740 nm region are less defined. The black color could be caused by slightly higher concentrations of Fe, the smaller size of individual crystals in the aggregate reducing macroscopic transparency, and/or the presence of submicroscopic inclusions
Optical and Luminescence Spectroscopy of Varicolored Gem Spinel from Mogok, Myanmar and Lục Yên, Vietnam
No full textWe studied 12 crystal fragments of natural spinel from Mogok, Myanmar and Lục Yên, Vietnam. All samples were crystal fragments of various shapes and sizes and several of them had gemological quality. Studied samples are enriched in Cr, V, Fe2+, Fe3+, Zn, which are responsible for its resulting color. They could be divided into groups of V-Cr spinels with Cr 0.001–0.006 apfu, V 0.001–0.004 apfu, and Fe spinels containing increased Fe2+ (0.001–0.017 apfu) and Fe3+ (0.004–0.012 apfu). Some samples show luminescence bands at 677, 685, 697, 710, and 718 nm assigned to Cr3+. The optical absorption spectra of spinels were divided into two groups of V-Cr and Fe spinels based on the dominant element acting on optical spectra. The optical spectrum of V-Cr spinels can be divided into two zones (1) 420–550 nm (V3+ and Cr3+ absorption); (2) 640–1000 nm (Fe2+-Fe3+ charge transfer). The optical absorption spectra of Fe spinels can also be divided into two zones (1) 410–650 nm (Fe2+-Fe3+ charge transfer) and (2) 770–1000 nm (Fe2+). This variation in chromophores results in the differences in color: V-Cr spinels are pink to red, Fe spinels are in shades of blue as well as yellow and pink
The REE-Induced Absorption and Luminescence in Yellow Gem-Quality Durango-Type Hydroxylapatite from Muránska Dlhá Lúka, Slovakia
No full textIn talc-magnesite veins in serpentinite near Muránska Dlhá Lúka (MDL), Slovakia, yellow euhedral to subhedral crystals apatite of a gem quality occur. It has a composition of hydroxylapatite with F− varying between 0.29 and 0.34 apfu, Cl− in range of 0.02–0.05 apfu and calculated OH− content between 0.62–0.68 apfu. Moreover, [CO3]2− molecules were identified by FTIR and Raman spectroscopy. MDL apatite contains only up to 0.003 apfu As5+ and Si4+ substituting for P5+; Ca is substituted by small amount of Na, Fe2+, Mn2+ (all up to 0.006 apfu), and Rare Earth Elements (REE—in total up to 0.017 apfu). Compared to trace-element composition of similar apatites from Durango, Mexico, the REE content in MDL apatite is around ten times lower with Nd > Ce >> La, its chondrite-normalized REE pattern has almost a horizontal slope and larger negative Eu anomaly. The MDL apatite is richer in Mn, Pb and Li, but poorer in As, V, Th and U. The concentrations of Sr and Y are similar. In the optical absorption spectra, the most prominent bands are at 585–590 nm (Nd3+) and between 600 and 800 nm (Mn2+, Ce3+-SiO3− photochromic center and Nd3+). The photoluminescence spectrum of MDL apatite shows bands between 550 and 620 nm (Dy3+, Sm3+, Pr3+ and also Mn2+) which likely enhance its yellow color. MDL hydroxylapatite likely formed from fluids derived from granitic rocks as evidenced by the chondrite-normalized REE patterns, Li, Mn and Y concentrations. The Sr content reflects the host-rock serpentinite composition. Fluids for its crystallization were likely derived from Muráň complex orthogneisses by the Alpine deformation and recrystallization in greenschist to lower amphibolite facies
