A cDNA encoding mouse tyrosinase was inserted into a plasmid containing the provirus of a replication competent avian leukosis virus (ALV). A viral stock produced from the plasmid was used to infect ...cultured tyrosinase-negative (ca/ca) unpigmented chick embryo melanocytes. Five days after infection many cells were producing very dark discrete melanosomes.
Nowadays 80% of scandium in China is obtained from titanium pigments production waste through a complex purification process. The study mainly focused on the purification of Sc from its concentrate ...generated from titanium pigments production waste by solvent extraction. Several extractants have been tried and 10% D2EHPA - 5% TBP - 85% sulfonated kerosene exhibited the best extraction performance towards Sc in 7 mol/L H2SO4 solution, so it was selected as the oil phase. 0.5% of H2O2 was added into the concentrated solution which can effectively inhibit the extraction of Ti. Both the extraction and back extraction parameters are optimized. The preferred extraction conditions were obtained, i.e., acidity: 7 mol/L H2SO4, the phase ratio A/O: 10, room temperature, mixed contact time: 30 min, Sc concentrate: 10 g/L, that the extraction rate of Sc in the above conditions was nearly 100%. NaOH was used for back extraction with the stripping rate 99% on the following conditions: 5 mol/L NaOH stripping for 30 min at a phase ratio A/O: 1 at 90 °C. Finally, H2C2O4 was used to further purify the back extraction product and Sc2(C2O4)3 precipitant formed. The final product Sc2O3 with a purity over 99.5% was obtained by calcining Sc2(C2O4)3 at 1000 °C for 2 h. A conceptual process for Sc purification was put forward and proved. The total recovery yield of Sc in the whole process is 95%.
10% D2EHPA - 5% TBP - 85% sulfonated kerosene was selected with the extraction efficiency of Sc over 99.9%. The usage of H2O2 can promote the extraction of scandium and inhibit the extraction of titanium. NaOH was used for back extraction with the stripping rate of 99%. H2C2O4 was used to further purify the back extraction product and Sc2(C2O4)3 precipitant formed, which is roast obtained Sc2O3. Finally, a conceptual process of purification Sc from its concentrate was put forward and proved in the laboratory with 99.5% Sc2O3 product obtained with a yield of 95%. Display omitted
•Several extractants were tried to purify Sc from its concentrate.•10% D2EHPA - 5% TBP - 85% sulfonated kerosene was selected with the extraction efficiency of Sc over 99%.•0.5% of H2O2 was added into the feed solution to inhibit the extraction of Ti.•5 mol/L NaOH at 90 °C can effectively strip Sc with the stripping rate of about 99%.•A simple flowsheet for Sc purification was proposed and 99.5% Sc2O3 was obtained with the yield over 95%.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, the continuous microwave production of (Pr, Zr)SiO2 and (Ti, Sb, Cr)O2 pigments was modelled. The mathematical model includes a two-way coupling between the Maxwell’s equations and the ...heat equation as well as the coupling between the thermal and the chemical interfaces. The COMSOL Multiphysics software was used together with a specially designed MATLAB controller developed to automatically manage the input power and the cavity impedance. A single-mode cavity operating at 2.45GHz, together with a rectangular waveguide, was used. A chemical model using experimental data was implemented using a model-fitting approach to predict the chemical conversion with time. Results show that the model-fitting method yields a good agreement with the experimental data. Attenuation occurs significantly within the material as the dielectric properties have high values. As such, prohibitive temperatures can be attained easily, although this was taken into account by the developed controller to manage the input power properly. The electromagnetic efficiency is highly dependent on the thermal field, making the boundary convection coefficient the parameter that affects the most the electromagnetic heating performance. A parametric study, that includes the variation of velocity and convection coefficient, was performed to access the impact of these variables in the efficiency of the process. The results show that increasing the velocity leads to a reduction of the maximum temperature, improving the electromagnetic efficiency. Moreover, the green-house gas specific emissions are lower when compared to the conventional process. The thermal conductivity is also a crucial parameter that can contribute to the electric field attenuation and the superficial heating.
Display omitted
•Multi-physics model solves chemical, energy and electromagnetic equations.•Exothermic chemical models are validated for two specific ceramic pigments.•The developed control algorithm adjusts the plunger position for the highest energy efficiency.•Automatic procedure obtains converged solutions with a complete chemical conversion.•With microwave technology GHG emissions can be reduced 75% in France and 98% in Sweden.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Three cyanobacterial strains of the genus Spirulina, i.e., LAMB171, LAMB172, and LAMB220, were cultivated at different CO2 concentrations in a columnar photobioreactor to determine the most optimal ...strain for CO2 mitigation and co-production of bioactive substances, specifically carotenoids, C-phycocyanin and allophycocyanin (A-PC). The best biomass production and the highest CO2 fixation rate were obtained at 10% CO2 concentration for all three Spirulina strains evaluated in the present study. When compared with the control group, the contents of chlorophyll a, carotenoids, C-PC, and A-PC were more optimal in the investigated Spirulina strains at lower CO2 concentrations (2% and 5%). However, the content of these bioactive substances was not significantly different at a 10% CO2 concentration compared with that at lower CO2 concentrations. Overall, it was determined that 10% CO2 concentration was noted to be most suitable for the production of these bioactive substances owing to the highest biomass productivity for all three Spirulina strains. Besides, LAMB220 was found to be the most effectively mitigated CO2 in three strains on account of its high biomass productivity and excellent C-fixation capability, while LAMB171 and LAMB172 species were more suitable for the production of pigments at a 10% CO2 concentration.
•Three Spirulina strains were cultivated at different CO2 concentrations in a columnar photobioreactor.•The highest CO2 fixation rate was found at 10% CO2 concentration for all three strains.•10% CO2 concentration was the most suitable for production of the bioactive substances.•LAMB220 was the species most effectively mitigated CO2.•LAMB171 and 172 were more suitable for the production of pigments at 10% CO2 concentration.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The stress induced by Cr(III), Cr(VI) and Ni(II) was determined, by using Sinapis alba plant, as root and shoot growth inhibition, dry and fresh mass production, water translocation to upper plant ...parts, photosynthetic pigments production and metal accumulation and translocation through the plant. For growth inhibition the following ranks orders were arranged: for roots Cr(VI) greater than or equal to Ni(II) >> Cr(III); for shoots Ni(II) > Cr(VI) >> Cr(III). When the relationship between dry (DM) and fresh (FM) mass was determined, the DM fraction was increased parallel with increased metal concentrations in order Cr(VI) > Ni(II) > Cr(III). This indicates a reduction in water uptake. Water content was reduced in all cases very rapidly, mainly in the roots and obtained results indicated that Cr and Ni inhibited water absorption by the roots, but not water translocation into the upper plant parts. The strongest unfavorable effect on the production of photosynthetic pigments had again Cr(VI) and the lowest Cr(III). Metals reduced more Chi a than Chi b production and their effect on carotenoids was mostly stimulative. Accumulation of all tested metals was higher in the roots and because transfer factor (TF) was lowers than 1, the transport of Cr and Ni from roots to shoots was restricted.
The priority of this study was to investigate how selenium influences toxicity of Cd, Zn, Cu and Pb when the metals appear in the hydroponic solution in pairs. As a model subject mustard seedlings ...(Sinapis alba L.) were used. Except phytotoxicity of individual metals and Se-metal combinations determined through photosynthetic pigments content (chlorophyll a, b, total carotenoids) also metal accumulation in the roots and shoots was determined by the AAS method. Se in all metal combinations reduced the unfavourable effect of other metals tested for chlorophylls content, however, for carotenoids primarily the opposite effect occurred. For metal accumulation in the roots and shoots it was confirmed that Se stimulated only Cd (about 24%) and slightly Cu (about 9%) accumulation in the roots, while in the shoots there was inhibited accumulation of all metals tested. The strongest inhibition was observed in Pb accumulation (84.9%). This fact indicates that Se generates some barriers for metal transfer from the roots to the underground plant parts. In contrast, Cu, Zn, Pb and Cd increased Se accumulation in the roots in the range of 4 (in combination with Cu) to 68% (in combination with Cd) and in the shoots in the range of 11 (in combination with Pb and Zn) to 44% (in combination with Cd). In the shoots only Cu inhibited Se accumulation (about 67%).
The chronic ecotoxicological effects of Cd, Cu, Pb, Se and Zn were determined within this study. Mustard seedlings (Sinapis alba L.) were used as a model subject for the tests. The phytotoxicity was ...determined through the root growth inhibition and photosynthetic pigments production (chlorophyll a, b, total carotenoids). The metal accumulation in the roots and cotyledons was also determined using the AAS methods. On the basis of IC50 values and their 95% confidence intervals (CI) for the root elongation of S. alba seedlings, metals can be arranged in the rank order of inhibition as follows: Cu > Se > Cd > Zn >> Pb. When the photosynthetic pigments production was determined, Se demonstrated the lowest inhibitory effect on all pigment types and Pb did the highest. The accumulated amount of metals from hydroponic solution into the roots and cotyledons decreased in the order Cd > Zn > Se > Pb > Cu.
PDF
