Study of Forms of Compounds of Vanadium and Other Elements in Samples of Pyrometallurgical Enrichment of Ash from Burning Oil Combustion at Thermal Power Plants.

The results of the processing of ash from the combustion of fuel oil after roasting with the addition of Na2CO3 followed by aluminothermic melting are presented. As a result, metallic nickel and vanadium slag were obtained. Studies of slag, metal, and deposits on the electrode were carried out. The resulting metal contains about 90 wt% Ni. The main phases of scurf on the electrode are a solid solution based on periclase (Mg1-x-y-zNixFeyVzO), sodium-magnesium vanadate (NaMg4(VO4)3), and substituted forsterite (Mg2-x-yFexNiySiO4). The processing of ash made it possible to significantly increase the concentration of vanadium and convert it into more soluble compounds. Vanadium amount increased from 16.2 in ash to 41.4-48.1 V2O5 wt% in slag. The solubility of vanadium was studied during aqueous leaching and in solutions of H2SO4 and Na2CO3. The highest solubility of vanadium was seen in H2SO4 solutions. The degree of extraction of vanadium into the solution during sulfuric acid leaching of ash was 18.9%. In slag, this figure increased to 72.3-96.2%. In the ash sample, vanadium was found in the form of V5+, V4+ compounds, vanadium oxides VO2 (V4+), V2O5 (V5+), and V6O13, and nickel orthovanadate Ni3(VO4)2 (V5+) was found in it. In the slag sample, vanadium was in the form of compounds V5+, V4+, V3+, and V(0÷3)+; V5+ was presented in the form of compounds vanadate NaMg4(VO4)3, NaVO3, and CaxMgyNaz(VO4)6; V3+ was present in spinel (FeV2O4) and substituted karelianite (V2-x-y-zFexAlyCrzO3). In the obtained slag samples, soluble forms of vanadium are due to the presence of sodium metavanadate (NaVO3), a phase with the structure of granate CaxMgyNaz(VO4)6 and (possibly) substituted karelianite (V2-x-y-zFexAlyCrzO3). In addition, spinel phases of the MgAl2O4 type beta-alumina (NaAl11O17), nepheline (Na4-xKxAl4Si4O16), and lepidocrocite (FeOOH) were found in the slag samples.

Analysis of Hydrometallurgical Methods for Obtaining Vanadium Concentrates from the Waste by Chemical Production of Vanadium Pentoxide.

The paper describes hydrometallurgical methods to recycle wastes of vanadium pentoxide chemical fabrication. Sludges containing a significant amount of V2O5 can be considered as an additional source of raw materials for vanadium production. We studied the one-stage leaching method using various iron-based reductants for converting V5+ to V4+ in a solution allowing to precipitate V when its concentration in the solution is low. As a result of the reduction leaching with further precipitation, we obtained concentrates with V2O5 content of 22-26% and a high amount of harmful impurities. Multistage counterflow leaching can be used to fabricate solutions with vanadium pentoxide concentration suitable for vanadium precipitation by hydrolysis and adding ammonium salts. The solutions with V2O5 content of ≈15 g/L can be obtained from the initial sludge by three-stage counterflow vanadium leaching. A concentrate with a content of 78 wt% V2O5 can be precipitated from these solutions at pH = 2.4 by adding ammonium chloride. Additionally, concentrate with V2O5 content of ≈94 wt% was precipitated from the solution with a concentration of >20 g/L V2O5 obtained from the roasted sludge. The concentrates were purified for increasing the vanadium content to 5-7%. The consumption and technological parameters of the considered processes are presented in the paper.

Vanadium Chemical Compounds forms in Wastes of Vanadium Pentoxide Production.

A big amount of solid wastes or dump sludges is generated after leaching vanadium (V) from a roasted mixture. As the vanadium content in these tailings is comparable to its concentration in traditional vanadium sources such as titanomagnetite ores or a vanadium converter slag, these wastes could be recycled to extract additional vanadium. Therefore, this research was aimed on studies of vanadium-containing sludges resulting from hydrometallurgical production of vanadium pentoxide to find an optimal technology for V extraction. The material composition of industrial and synthetic sludge samples was studied by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), secondary ions mass spectroscopy (SIMS), and X-ray photoelectron spectroscopy (XPS, ESCA). The paper demonstrates the presence of vanadium in sludges, not only in spinels in 3+ oxidation degree, but also in other compounds containing V4+ and V5+. It was found that vanadium substitutes a set of elements in minerals except spinel. The dependence between the content of insoluble vanadium compounds and V oxidation degree was determined.

Features of the Microstructure and Chemical Compositions of Vanadium-Containing Slags Including Determination of Vanadium Oxidation Degrees.

Metallurgical vanadium-containing converter slag could be used as an alternative vanadium source. The development of a physico-chemical basis for the comprehensive processing of industrial vanadium-containing debris requires information about their elemental composition as well as the oxidation degrees of the elements and forms of compounds in order to solve two key problems: a better utilization of industrial wastes and a lowering of environment impact. This research was aimed at the development of methods to determine the fractions of elements and their oxidation degrees in vanadium-containing industrial debris exemplified by basic oxygen converter vanadium slags. A set of bulk and surface analysis methods (X-ray fluorescence analysis (XRF), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS)) was used for this purpose: based on results of elemental analysis, SEM detects the oxide phases of metals, while an analysis of the XPS lines' fine structures provides fractions of corresponding elements with definite oxidation degrees. In this way, one can determine the fractions of vanadium in multiple oxidation degrees in slags and can properly select the chemicals and parameters of chemical processes for its fullest extraction.

Thermoplasmonic Semitransparent Nanohole Electrodes.

Nonradiative decay of plasmons in metallic nanostructures offers unique means for light-to-heat conversion at the nanoscale. Typical thermoplasmonic systems utilize discrete particles, while metal nanohole arrays were instead considered suitable as heat sinks to reduce heating effects. By contrast, we show for the first time that under uniform broadband illumination (e.g., the sun) ultrathin plasmonic nanohole arrays can be highly competitive plasmonic heaters and provide significantly higher temperatures than analogous nanodisk arrays. Our plasmonic nanohole arrays also heat significantly more than nonstructured metal films, while simultaneously providing superior light transmission. Besides being efficient light-driven heat sources, these thin perforated gold films can simultaneously be used as electrodes. We used this feature to develop "plasmonic thermistors" for electrical monitoring of plasmon-induced temperature changes. The nanohole arrays provided temperature changes up to 7.5 K by simulated sunlight, which is very high compared to previously reported plasmonic systems under similar conditions (solar illumination and ambient conditions). Both temperatures and heating profiles quantitatively agree with combined optical and thermal simulations. Finally, we demonstrate the use of a thermoplasmonic nanohole electrode to power the first hybrid plasmonic ionic thermoelectric device, resulting in strong solar-induced heat gradients and corresponding thermoelectric voltages.

In vivo polymerization and manufacturing of wires and supercapacitors in plants.

Electronic plants, e-Plants, are an organic bioelectronic platform that allows electronic interfacing with plants. Recently we have demonstrated plants with augmented electronic functionality. Using the vascular system and organs of a plant, we manufactured organic electronic devices and circuits in vivo, leveraging the internal structure and physiology of the plant as the template, and an integral part of the devices. However, this electronic functionality was only achieved in localized regions, whereas new electronic materials that could be distributed to every part of the plant would provide versatility in device and circuit fabrication and create possibilities for new device concepts. Here we report the synthesis of such a conjugated oligomer that can be distributed and form longer oligomers and polymer in every part of the xylem vascular tissue of a Rosa floribunda cutting, forming long-range conducting wires. The plant's structure acts as a physical template, whereas the plant's biochemical response mechanism acts as the catalyst for polymerization. In addition, the oligomer can cross through the veins and enter the apoplastic space in the leaves. Finally, using the plant's natural architecture we manufacture supercapacitors along the stem. Our results are preludes to autonomous energy systems integrated within plants and distribute interconnected sensor-actuator systems for plant control and optimization.

Total phenol analysis of weakly supported water using a laccase-based microband biosensor.

The monitoring of phenolic compounds in wastewaters in a simple manner is of great importance for environmental control. Here, a novel screen printed laccase-based microband array for in situ, total phenol estimation in wastewaters and for water quality monitoring without additional sample pre-treatment is presented. Numerical simulations using the finite element method were utilized for the characterization of micro-scale graphite electrodes. Anodization followed by covalent modification was used for the electrode functionalization with laccase. The functionalization efficiency and the electrochemical performance in direct and catechol-mediated oxygen reduction were studied at the microband laccase electrodes and compared with macro-scale electrode structures. The reduction of the dimensions of the enzyme biosensor, when used under optimized conditions, led to a significant improvement in its analytical characteristics. The elaborated microsensor showed fast responses towards catechol additions to tap water - a weakly supported medium - characterized by a linear range from 0.2 to 10 µM, a sensitivity of 1.35 ± 0.4 A M(-1) cm(-2) and a dynamic range up to 43 µM. This enhanced laccase-based microsensor was used for water quality monitoring and its performance for total phenol analysis of wastewater samples from different stages of the cleaning process was compared to a standard method.

Modeling of charge transport in ion bipolar junction transistors.

Spatiotemporal control of the complex chemical microenvironment is of great importance to many fields within life science. One way to facilitate such control is to construct delivery circuits, comprising arrays of dispensing outlets, for ions and charged biomolecules based on ionic transistors. This allows for addressability of ionic signals, which opens up for spatiotemporally controlled delivery in a highly complex manner. One class of ionic transistors, the ion bipolar junction transistors (IBJTs), is especially attractive for these applications because these transistors are functional at physiological conditions and have been employed to modulate the delivery of neurotransmitters to regulate signaling in neuronal cells. Further, the first integrated complementary ionic circuits were recently developed on the basis of these ionic transistors. However, a detailed understanding of the device physics of these transistors is still lacking and hampers further development of components and circuits. Here, we report on the modeling of IBJTs using Poisson's and Nernst-Planck equations and the finite element method. A two-dimensional model of the device is employed that successfully reproduces the main characteristics of the measurement data. On the basis of the detailed concentration and potential profiles provided by the model, the different modes of operation of the transistor are analyzed as well as the transitions between the different modes. The model correctly predicts the measured threshold voltage, which is explained in terms of membrane potentials. All in all, the results provide the basis for a detailed understanding of IBJT operation. This new knowledge is employed to discuss potential improvements of ion bipolar junction transistors in terms of miniaturization and device parameters.

ß5i subunit deficiency of the immunoproteasome leads to reduced Th2 response in OVA induced acute asthma.

The immunoproteasome subunit ß5i has been shown to play an important role in Th1/Th17 driven models of colitis and arthritis. However, the function of ß5i in Th2 dependent diseases remains enigmatic. To study the role of ß5i in Th2-driven pathology, ß5i knockout (KO) and control mice were tested in different models of experimental allergic asthma. ß5i-deficient mice showed reduced OVA/Alum- and subcutaneous/OVA-induced acute asthma with decreased eosinophilia in the bronchoalveolar lavage (BAL), low OVA-specific IgG1 and reduced local and systemic Th2 cytokines. While Th2 cells in the lungs were reduced, Tregs and Th1 cells were not affected. Attenuated asthma in ß5i KO mice could not be attributed to defects in OVA uptake or maturation of dendritic cells in the lung. Surprisingly, ß5i deficient mice developed HDM asthma which was comparable to control mice. Here, we present novel evidence for the requirement of the ß5i immunosubunit to generate a strong Th2 response during OVA- but not HDM-induced acute asthma. The unexpected role of ß5i in OVA asthma remains to be clarified.

Crystal structure analysis of a fatty acid double-bond hydratase from Lactobacillus acidophilus.

Bacteria have evolved mechanisms for the hydrogenation of unsaturated fatty acids. Hydroxy fatty acid formation may be the first step in such a process; however, knowledge of the structural and mechanistic aspects of this reaction is scarce. Recently, myosin cross-reactive antigen was shown to be a bacterial FAD-containing hydratase which acts on the 9Z and 12Z double bonds of C16 and C18 non-esterified fatty acids, with the formation of 10-hydroxy and 10,13-dihydroxy fatty acids. These fatty acid hydratases form a large protein family which is conserved across Gram-positive and Gram-negative bacteria with no sequence similarity to any known protein apart from the FAD-binding motif. In order to shed light on the substrate recognition and the mechanism of the hydratase reaction, the crystal structure of the hydratase from Lactobacillus acidophilus (LAH) was determined by single-wavelength anomalous dispersion. Crystal structures of apo LAH and of LAH with bound linoleic acid were refined at resolutions of 2.3 and 1.8 Å, respectively. LAH is a homodimer; each protomer consists of four intricately connected domains. Three of them form the FAD-binding and substrate-binding sites and reveal structural similarity to three domains of several flavin-dependent enzymes, including amine oxidoreductases. The additional fourth domain of LAH is located at the C-terminus and consists of three α-helices. It covers the entrance to the hydrophobic substrate channel leading from the protein surface to the active site. In the presence of linoleic acid, the fourth domain of one protomer undergoes conformational changes and opens the entrance to the substrate-binding channel of the other protomer of the LAH homodimer. The linoleic acid molecule is bound at the entrance to the substrate channel, suggesting movement of the lid domain triggered by substrate recognition.

A key role for NF-κB transcription factor c-Rel in T-lymphocyte-differentiation and effector functions.

The transcription factors of the Rel/NF-κB family function as key regulators of innate and adoptive immunity. Tightly and temporally controlled activation of NF-κB-signalling pathways ensures prevention of harmful immune cell dysregulation, whereas a loss of control leads to pathological conditions such as severe inflammation, autoimmune disease, and inflammation-associated oncogenesis. Five family members have been identified in mammals: RelA (p65), c-Rel, RelB, and the precursor proteins NF-κB1 (p105) and NF-κB2 (p100), that are processed into p50 and p52, respectively. While RelA-containing dimers are present in most cell types, c-Rel complexes are predominately found in cells of hematopoietic origin. In T-cell lymphocytes, certain genes essential for immune function such as Il2 and Foxp3 are directly regulated by c-Rel. Additionally, c-Rel-dependent IL-12 and IL-23 transcription by macrophages and dendritic cells is crucial for T-cell differentiation and effector functions. Accordingly, c-Rel expression in T cells and antigen-presenting cells (APCs) controls a delicate balance between tolerance and immunity. This review gives a selective overview on recent progress in understanding of diverse roles of c-Rel in regulating adaptive immunity.

Myosin cross-reactive antigen of Streptococcus pyogenes M49 encodes a fatty acid double bond hydratase that plays a role in oleic acid detoxification and bacterial virulence.

The myosin cross-reactive antigen (MCRA) protein family is highly conserved among different bacterial species ranging from Gram-positive to Gram-negative bacteria. Besides their ubiquitous occurrence, knowledge about the biochemical and physiological function of MCRA proteins is scarce. Here, we show that MCRA protein from Streptococcus pyogenes M49 is a FAD enzyme, which acts as hydratase on (9Z)- and (12Z)-double bonds of C-16, C-18 non-esterified fatty acids. Products are 10-hydroxy and 10,13-dihydroxy fatty acids. Kinetic analysis suggests that FAD rather stabilizes the active conformation of the enzyme and is not directly involved in catalysis. Analysis of S. pyogenes M49 grown in the presence of either oleic or linoleic acid showed that 10-hydroxy and 10,13-dihydroxy derivatives were the only products. No further metabolism of these hydroxy fatty acids was detected. Deletion of the hydratase gene caused a 2-fold decrease in minimum inhibitory concentration against oleic acid but increased survival of the mutant strain in whole blood. Adherence and internalization properties to human keratinocytes were reduced in comparison with the wild type. Based on these results, we conclude that the previously identified MCRA protein can be classified as a FAD-containing double bond hydratase, within the carbon-oxygen lyase family, that plays a role in virulence of at least S. pyogenes M49.

Selective protection of nuclease-sensitive sites in siRNA prolongs silencing effect.

Small interfering RNAs (siRNAs) are considered as potent agents for specific gene silencing; however, nuclease sensitivity of siRNA limits their biomedical applications. Till date, no universal methodology has been developed to improve the nuclease resistance of siRNA, preserving low toxicity and high activity. In this study, we proposed an algorithm for the site-specific modification of siRNAs based on the mapping of their nuclease-sensitive sites in the presence of serum followed by the incorporation of 2'-O-methyl analogs of ribonucleotides at the identified positions of cleavage. We found that the protection of nuclease-sensitive sites considerably enhanced nuclease resistance of siRNA and only slightly reduced the efficiency of silencing. Modification of all nuclease-sensitive sites prolonged the duration of the silencing effect of the siRNA compared to nonmodified, partially modified, or randomly modified siRNA of the same sequence. This study showed that the targeted chemical modification of nuclease-sensitive sites could provide highly efficient siRNA-based therapeutics for the control of disease-related genes.