High Oxide Content Research Articles

Development of thermally stable glass from SiO2-Bi2O3-PbO-ZnO-BaO oxide system suitable for all-solid photonic crystal fibers

The series of SiO2-Bi2O3-PbO-ZnO-BaO and SiO2-TiO2-Bi2O3-PbO-Na2O glasses were synthetized to obtain non-crystallizing materials, dedicated to fabrication of photonic crystal fibers. During composition development, the thermal properties were investigated according to the change of chemical composition. The glasses contain high concentrations of heavy metal oxides for high refractive index, large nonlinear refractive index and spectrally broad transmission window from 0.5 to 4.5 μm. Their thermal properties are optimized to enable drawing of all-solid glass photonic crystal fibers in tandem with previously designed highly nonlinear glass PBG81 based on SiO2-Ga2O3-Bi2O3-PbO-CdO system. This creates novel dual glass combinations for PCF fibers. We have also investigated influence of melting conditions on the final thermal and optical properties, including absorption from water contamination at around 2.8 μm.

Tectonic, climatic, and diagenetic control of magnetic properties of sediments from Kumano Basin, Nankai margin, southwestern Japan

Integrated Ocean Drilling Program (IODP) Site C0002 was cored in the Kumano Basin, which is a forearc basin in the Nankai margin of southwest Japan. The uppermost 1052.5m of sediment in the accretionary prism, slope, and overlying forearc basin was recovered discontinuously during Expedition 315. Magnetic minerals from Site C0002 were studied to understand sedimentary, tectonic, and diagenetic processes in this forearc environment. Four rock magnetic units (A, B, C, and D) are identified. In the forearc basin sediments of Unit A, high concentrations of detrital magnetic iron oxides in surface sediments give way to progressive diagenetic dissolution with depth. Nevertheless, large titanomagnetite particles survived diagenetic dissolution along with magnetic nanoinclusions within host silicates that preserve a relict magnetic signal that records climatic modulation of sediment delivery to the Kumano Basin. The authigenic iron sulphides, ferrimagnetic greigite and paramagnetic pyrite, formed in association with gas hydrates and anaerobic oxidation of methane in the forearc basin sediments of Unit B. Methane venting from deeper within the slope sediments of Unit C and accretionary prism sediments of Unit D has given rise to formation of pyrite aggregates along sediment fractures and has contributed to further diagenetic depletion of magnetic signals in these units. Structural evolution of the Kumano Basin has caused migration of the gas hydrate stability zone (GHSZ) through time so that the Site C0002 sediments record both the present and fossil GHSZ positions. Magnetic properties of Kumano Basin sediments provide insights into the interplay between diagenetic, climatic, and tectonic processes that controlled the sedimentary evolution of this forearc basin.

Photocatalytic Oxidation of Glucose into Formate on Nano TiO2 Catalyst

Formic acid, as an excellent hydrogen-storage material, has recently become increasingly important. Previous conversion of biomass into formic acid suffers from problems of strict operation conditions such as the use of a high concentration of H2O2 oxidant and alkali at higher temperatures or the precious metal catalysts. Here, a straightforward photocatalytic method to selectively convert glucose into formate is first reported. Using a nano TiO2 catalyst, we show that glucose can be efficiently converted into formic acid with a high yield of 35% at ambient condition with 0.03 M NaOH concentration, and the proposed method also worked on xylose for formate production. The conversion of glucose into formic acid is mainly attributed to the accelerated formation of active oxidative radicals (O2•–, •OH) in the presence of hydroxyl ions, and also, hydroxyl ions adjust the charge of the TiO2 surface and control the adsorption of glucose and the desorption of formic acid. These results open up a new approach towa...

Regulation of ash-fusion behaviors for high ash-fusion-temperature coal by coal blending

Blending is a promising method to modify the ash-fusion characteristics of coal to meet gasification requirements. To investigate the variation in ash-fusion behavior for high ash-fusion-temperature (AFT) coal through coal blending and its regulating mechanism, the ash-chemistry characteristics of four coals (Nantun, Pengzhuang, Biaodian, and Xiangyuan) were analyzed. Mineral-transformation behaviors in the mixed ashes were investigated by X-ray powder diffractometry using normalized reference intensity ratio software, scanning electron microscopy analyzer equipped with energy-dispersive X-ray spectrometry, and FactSage software. Pengzhuang and Biaodian coals, AFTs meet entrained-flow gasifier requirements when the Xiangyuan mass ratio reaches 20%. The Nantun requires a Xiangyuan mass ratio of XY >30% because of its high aluminum oxide content. The required Xiangyuan optimal blending mass ratio is 40%–70% for the three high AFT coals to meet gasification requirements in the entrained-flow gasifier. An increased Xiangyuan mass ratio leads to decreasing contents of high melting-point mullite and silica and increasing contents of low melting-point anorthite, hercynite, gehlenite, and hedenbergite. Amorphous matter in three mixed ash types resulted in a decrease in their AFTs. The variation in liquid phase under certain conditions reflects the change in AFT.

The 3D Nanoscale Evolution of Platinum–Niobium Oxide Fuel Cell Catalysts via Identical Location Electron Tomography

Current state‐of‐the‐art catalysts for polymer electrolyte membrane fuel cells, comprised of platinum nanoparticles on a high surface area carbon support, are susceptible to platinum dissolution and carbon support corrosion during operation. The use of transition metal oxides in the support material is proposed to stabilize the catalyst material by minimizing platinum dissolution and carbon corrosion. Here, the 3D structural changes are tracked for a hybrid Pt–Nb oxide on carbon catalyst before and after potential cycling utilizing identical location electron tomography. Pt dissolution is observed to varying degrees in both high and low Nb oxide content structures and appreciable carbon support corrosion in the high Nb oxide content structure but not in the low Nb oxide structure.

Composition and structure of calcium aluminosilicate microspheres

The composition was studied of calcium aluminosilicate microspheres of three morphological types in high-calcium fly ash from combustion of brown coal from the Kansk-Achinsk basin in slag-tap boilers at temperatures from 1400 to 1500°С and sampled in the first field of electrostatic precipitators at the Krasnoyarsk Cogeneration Power Station no. 2 (TETs-2). Gross compositions and the composition of local areas were determined using a scanning electron microscopy technique and an energy-dispersive analysis with full mapping of globules. With a high content of basic oxides O ох (68 to 79 wt %) and a low content of acid oxides K ох (21 to 31 wt %), type 1 microspheres are formed. They consist of heterogeneous areas having a porous structure and crystalline components in which the content of CaO, SiO2, or Al2O3 differs by two to three times and the content of MgO differs by seven times. With a lower content of O ох (55 to 63 wt %) and an elevated content of K ох (37 to 45 wt %), type 2 microspheres are formed. They are more homogeneous in the composition and structure and consist of similar crystalline components. Having a close content of O ох (46 to 53 wt %) and K ох (47 to 54 wt %), type 3 microspheres, which are a dense matter consisting of amorphous substance with submicron- and nanostructure of crystalline components, are formed. The basic precursor in formation of high-calcium aluminosilicate microspheres is calcium from the organomineral matter of coals with various contribution of Mg, Fe, S, or Na from the coal organic matter and Al, Fe, S, or Si in the form of single mineral inclusions in a coal particle. On the basis of the available data, the effect was analyzed of the composition of a CaO–MgO–Al2O3–SiO2–FeO system on the melting and viscous properties of the matter in microspheres and formation of globules of different morphology. The results of this analysis will help to find a correlation with properties of microspheres in their use as functional microaggregates in cement or polymeric composite materials, or in the production of ceramic membranes or zeolite sorbents.

Enzymatic-photocatalytic synergetic effect on the decolorization of dyes by single chloroperoxidase molecule immobilization on TiO2 mesoporous thin film

A chloroperoxidase (CPO) -TiO2 thin film type enzyme reactor was constructed by single chloroperoxidase molecule immobilization on TiO2 mesoporous thin film. The CPO-TiO2 enzyme reactor showed an enzymatic-photocatalytic synergetic effect, 1+1>2, when applied in the decolorization of azo dye crocein orange G. Moreover, the enzyme reactor made it possible that the photocatalytic catalysis was carried out under natural sunlight instead of ultraviolet radiation. The synergetic effect was studied by PL emission spectroscopy with terephthalic acid used as a probe molecule to investigate the formation of ·OH radicals.The mesoporous TiO2, prepared by a sol-gel and dip-coating method, being spherical form without interconnectivity in a 3D pore systems of 8nm ~15nm pore size, matched the size of CPO molecules. Such an architecture was suitable for single CPO molecule immobilization, which enabled easy access of the substrates to enzyme active sites.The CPO-TiO2 enzyme reactor was very efficient. 98.61% decolorization efficiency of crocein orange G was achieved in 5min. It can be reused for seven cycles with no loss in activity. Compared with free CPO, the stability of CPO-TiO2 enzyme reactor against thermal denaturation and deactivation by high concentration of oxidants or in a strong acid-base environment was enhanced.

Chemistry and Redox Biology of Mycothiol.

Mycothiol (MSH, AcCys-GlcN-Ins) is the main low-molecular weight (LMW) thiol of most Actinomycetes, including the human pathogen Mycobacterium tuberculosis that affects millions of people worldwide. Strains with decreased MSH content show increased susceptibilities to hydroperoxides and electrophilic compounds. In M. tuberculosis, MSH modulates the response to several antituberculosis drugs. Enzymatic routes involving MSH could provide clues for specific drug design. Recent Advances: Physicochemical data argue against a rapid, nonenzymatic reaction of MSH with oxidants, disulfides, or electrophiles. Moreover, exposure of the bacteria to high concentrations of two-electron oxidants resulted in protein mycothiolation. The recently described glutaredoxin-like protein mycoredoxin-1 (Mrx-1) provides a route for catalytic reduction of mycothiolated proteins, protecting critical cysteines from irreversible oxidation. The description of MSH/Mrx-1-dependent activities of peroxidases helped to explain the higher susceptibility to oxidants observed in Actinomycetes lacking MSH. Moreover, the first mycothiol-S-transferase, member of the DinB superfamily of proteins, was described. In Corynebacterium, both the MSH/Mrx-1 and the thioredoxin pathways reduce methionine sulfoxide reductase A. A novel tool for in vivo imaging of the MSH/mycothiol disulfide (MSSM) status allows following changes in the mycothiol redox state during macrophage infection and its relationship with antibiotic sensitivity. Redundancy of MSH with other LMW thiols is starting to be unraveled and could help to rationalize the differences in the reported importance of MSH synthesis observed in vitro versus in animal infection models. Future work should be directed to establish the structural bases of the specificity of MSH-dependent enzymes, thus facilitating drug developments. Antioxid. Redox Signal. 28, 487-504.

Fluidizate‐Explosive Occurrences in Ophiolites as Indicator of the Subduction Zone Activity: The Urals Example

Fluidizate‐Explosive Occurrences in Ophiolites as Indicator of the Subduction Zone Activity: The Urals Example

Asphalt modified with superfine electric arc furnace steel dust (EAF dust) with high zinc oxide content

Electric arc furnace (EAF) dust is a complex ceramic-type hazardous waste generated by the metallurgical industry and produced worldwide in millions of tons. In this research EAF dust is evaluated as an admixture for asphalt up to 50wt%. The microstructure was analyzed by optical and scanning electron microscopy. Fourier transform infrared spectra, penetration, softening point and viscosity tests were conducted for all compositions. The results show the penetration point increases until 10wt% of waste and it then decreases. Conversely, the softening point, penetration index (PI) and viscosity, decrease after 5wt% and reaches a minimum at 10wt%. The particle distance was calculated using the composite materials theory, and other variables were analyzed in terms of inter-particle distance estimations.

Femtosecond Laser Modification of Zinc-Phosphate Glasses with High Silver Oxide Content

The processes involved in femtosecond laser modification of zinc-phosphate glass with a silver oxide ranging from 1 to 16 mol.% are studied and the optimal conditions for the formation of the luminescent microregions in the glass are determined.

Promoting effects of Fe2O3 to Pt electrocatalysts toward methanol oxidation reaction in alkaline electrolyte

Fe2O3 nanorods and hexagonal nanoplates were synthesized and used as the promoters for Pt electrocatalysts toward the methanol oxidation reaction (MOR) in an alkaline electrolyte. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry and chronoamperometry. The results show that the presence of Fe2O3 in the electrocatalysts can promote the kinetic processes of MOR on Pt, and this promoting effect is related to the morphology of the Fe2O3 promoter. The catalyst with Fe2O3 nanorods as the promoter (Pt-Fe2O3/C-R) exhibits much higher catalytic activity and stability than that with Fe2O3 nanoplates as the promoter (Pt-Fe2O3/C-P). The mass activity and specific activity of Pt in a Pt-Fe2O3/C-R catalyst are 5.32 A/mgPt and 162.7 A/m2Pt, respectively, which are approximately 1.67 and 2.04 times those of the Pt-Fe2O3/C-P catalyst, and 4.19 and 6.16 times those of a commercial PtRu/C catalyst, respectively. Synergistic effects between Fe2O3 and Pt and the high content of Pt oxides in the catalysts are responsible for the improvement. These findings contribute not only to our understanding of the MOR mechanism but also to the development of advanced electrocatalysts with high catalytic properties for direct methanol fuel cells.

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

Abstract. Rates and pathways of benthic organic carbon (Corg) oxidation were investigated in surface sediments of the Ulleung Basin (UB) characterized by high Corg contents ( > 2.5 %, dry wt.) and very high contents of Mn oxides ( > 200 µmol cm−3) and Fe oxides (up to 100 µmol cm−3). The combination of geochemical analyses and independently executed metabolic rate measurements revealed that Mn and Fe reduction were the dominant Corg oxidation pathways in the center of the UB, comprising 45 and 20 % of total Corg oxidation, respectively. By contrast, sulfate reduction was the dominant Corg oxidation pathway, accounting for 50 % of total Corg mineralization in sediments of the continental slope. The relative significance of each Corg oxidation pathway matched the depth distribution of the respective electron acceptors. The relative importance of Mn reduction for Corg oxidation displays saturation kinetics with respect to Mn oxide content with a low half-saturation value of 8.6 µmol cm−3, which further implies that Mn reduction can be a dominant Corg oxidation process even in sediments with lower MnO2 content as known from several other locations. This is the first report of a high contribution of manganese reduction to Corg oxidation in offshore sediments on the Asian margin. The high manganese oxide content in the surface sediment in the central UB was maintained by an extreme degree of recycling, with each Mn atom on average being reoxidized ∼ 3800 times before permanent burial. This is the highest degree of recycling so far reported for Mn-rich sediments, and it appears linked to the high benthic mineralization rates resulting from the high Corg content that indicate the UB as a biogeochemical hotspot for turnover of organic matter and nutrient regeneration.

List of Abstracts

. Production efficiency as well as the reduction of energy consumption and waste are the main drivers for the improvement of large-scale production in chemical industry. In addition, the demand for new processes – these days especially related to the chemical energy conversion as basis for the Energiewende – are additional triggers for innovation. Catalysis, well recognized by the public e.g. in form of the 3-way automobile catalyst, plays an important role for about 90% of all processes in chemical industry. The development of new and improved catalysts is a challenge for chemists – as is the search for new structural materials for mechanical engineers. Due to the often-necessary noble and thus expensive metals (e.g. palladium) in many catalysts, structural and chemical function have been developed separately in the two communities. Recent progress in catalytically active materials allows replacing expensive noble metals in selected catalytic processes by significant cheaper elements [1]. This offers the new perspective to combine structural and chemical functionality by innovative materials. Within this area, intermetallic compounds with their peculiar combination of crystal and electronic structure [2], represent an interesting class of materials to address this vision as will be shown in the contribution.

Advantage of NMR and FTIR Spectroscopy to Determine Structure Role of CeO<sub>2</sub> in Complicated Borosilicate Glasses: New Approach

Microstructure of complicated glasses in the system 30Na2O-2Al2O3-25 SiO2-xCeO2 (43-x) B2O3, x changes from 0.5 to 20 mol% have been extensively studied. Structural determination of glasses containing high cerium oxide content (≥8 mol% CeO2) was carried out by 11B NMR and FTIR spectroscopy. On the other hand, 29Si MAS NMR experiment is hardly to be applied to glasses of CeO2 > 8 mol%. This is due to the paramagnetic action which is raised by cerium cations causing dilution or delaying in the resonance phenomenon. It is evidenced from NMR data that sodium oxide is high enough to modify the glass forming units which constitute the skeleton of the glass. Ceria is as well as silica and B2O3 all are acting as glass forming species. Decreasing of both fraction of boron tetrahedral units (N4) and chemical shift of silicon nuclei (δ) confirm the role of CeO2 as a glass former. On the other hand, fast decrease in N4 and chemical shift of Si nuclei with further increasing CeO2 contents (≥8 mol%) gives a clear evidence that the ability of cerium oxide to participate as a network former increases with increasing its content. New approach is applied to determine the fraction of CeO4 as a glass forming units. In this approach, we use the common advantage of 11B NMR and FTIR spectroscopy to obtain Ce4 fraction. The latter species cannot be determined from NMR spectroscopy, since very high relaxation time and magnetization of ceria cause intensive spectral broadening which prevent resonance spectra to be appeared.

Al–Cu–Fe coatings manufactured by the flame spraying process

ABSTRACTTwo-hour milled (activated) Al–20Cu–15Fe (at%) powders were subjected to annealing at 600°C for 1 h. The phase and microstructural evolutions were characterized by X-ray diffractometry and scanning electron microscopy. Al7Cu2Fe and Al60Cu30Fe10 phases were formed after annealing. Both annealed and milled powders were consolidated using the flame spraying process. In both cases, FeAl(Cu) was the major phase while some oxides and α-Fe(Al,Cu) were also found. The coating produced from the milled powder was severely cracked and showed higher oxide content. The coating prepared from the annealed powder showed better quality. It was annealed at 600°C for 1 h to investigate the thermal stability of the various phases. All phases persevered after annealing while the Fe2Al5 phase was formed as a new phase.

Lithic raw material units based on magnetic properties: A blind test with Armenian obsidian and application to the Middle Palaeolithic site of Lusakert Cave 1

Classification of lithic artifacts’ raw materials based on macroscopic attributes (e.g., color, luster, texture) has been used to pull apart knapping episodes in palimpsest assemblages by attempting to identify artifacts produced through the reduction of an individual nodule. These classes are termed “raw material units” (RMUs) in the Old World and “minimum analytical nodules” in the New World. RMUs are most readily defined for lithic artifacts in areas with distinctive cherts and other siliceous raw materials, allowing pieces from different nodules to be recognized visually. Opportunities to apply RMUs, however, are strongly limited at sites where lithic material visual diversity is low. The magnetic properties of obsidian, which result from the presence of microscopic iron oxide mineral grains, vary spatially throughout a flow. Consequently, obsidian from different portions of a source (i.e., different outcrops or quarries) can vary in magnetic properties. This raises the possibility that magnetic-based RMUs (mRMUs) for obsidian artifacts could be effective to distinguish individual scatters from multiple production episodes and offer insights into spatial patterning within a site or specific occupation periods. First, we assess the potential of mRMUs using obsidian pebbles from Gutansar volcano in Armenia. Second, we evaluate the validity of this approach based on a double-blind test involving an experimental assemblage of Gutansar obsidian flakes. Cluster analysis can successfully discern flakes from obsidian specimens containing high concentrations of iron oxides. Obsidian with more magnetic material has more opportunities for that material to vary in unique ways (e.g., grain size, morphology, physical arrangement). Finally, we apply the mRMU approach to obsidian artifacts from the Middle Palaeolithic site of Lusakert Cave 1 in Armenia and compare the results to traditional RMU studies at contemporaneous sites in Europe. In particular, we seek – but do not find – differences between retouch flakes (which reflect rejuvenation of tools) and the other small debris (which reflect other reduction activities). This result likely reflects the local landscape, specifically the abundance of obsidian and, thus, little pressure to curate and retouch tools. As this approach is applied to additional sites, such findings will play a central role in regional assessments about the nature and timing of the Middle to Upper Palaeolithic “transition” and the relationship, or lack thereof, between technological behaviors and presumed population dynamics.

Ozonation of oxalic acid with an effective catalyst based on mesoporous MCM-41 supported manganese and cerium oxides

In this paper, mesoporous catalysts were prepared by deposition of various fractions of manganese and cerium oxides on MCM-41. The prepared catalyst samples presented uniform hexagonal pore structure in XRD, BET, and TEM characterization tests. The application of supported catalysts in the presence of ozone was found to be remarkably effective in elimination of oxalic acid in water with a conversion as high as 76–92%, compared to ozonation (10% removal), adsorption (20% removal), and catalytic ozonation using the support alone (56% removal). It was shown that the main portion of OA was degraded through reaction with hydroxyl radicals, which were generated by the application of the catalysts. In addition, the investigation of the activity of catalysts at various loadings of manganese and cerium oxides on the support showed that cerium oxide alone is a more effective than manganese oxide alone. However, the co-deposition of cerium oxide on a surface preloaded with fixed amount of manganese oxides led to mutual interactions, affecting the activity of the catalysts. At fixed loading of manganese oxides, the rate of degradation of oxalic acid was found to be much higher in the absence of any cerium oxide on the surface than high cerium oxide concentration. At optimum metal oxides proportions, the highest total organic carbon removal (90.3%) was achieved.

The Effects of Folate Supplementation on Carotid Intima-Media Thickness and Metabolic Status in Patients with Metabolic Syndrome

Background: This study was carried out to evaluate the effects of folate supplementation on carotid intima-media thickness (CIMT) and metabolic status among patients with metabolic syndrome (MetS). Methods: This randomized, double-blind, placebo-controlled trial was conducted among 60 patients with type 2 diabetes mellitus and coronary heart disease. They were all overweight in the age range 40-85 years. Participants were randomly divided into 2 groups: group A (n = 30) received 5 mg folate supplements and group B (n = 30) received placebo for 12 weeks. Results: Folate supplementation resulted in a significant reduction in maximum levels of left CIMT (-0.05 ± 0.13 vs. +0.02 ± 0.11 mm, p = 0.01) compared with the placebo. Changes in fasting plasma glucose (-2.2 ± 37.5 vs. +30.2 ± 65.8 mg/dl, p = 0.02), serum insulin concentration (-2.0 ± 10.7 vs. +3.0 ± 7.6 µIU/ml, p = 0.04) and homeostasis of assessment-estimated insulin resistance (-0.6 ± 2.3 vs. +0.9 ± 2.3, p = 0.01) in supplemented patients were significantly different from those of patients in the placebo group. Changes in serum triglycerides (p = 0.04), high-density lipoprotein-cholesterol (p = 0.001), high sensitivity C-reactive protein (p = 0.01) and plasma nitric oxide concentrations (p < 0.001) were significantly different between the supplemented patients and placebo group. Conclusions: Overall, 5 mg/day folate supplementation for 12 weeks among patients with MetS had beneficial effects on CIMT and the metabolic status.

In Situ Generation and Consumption of H2O2 by Bienzyme-Quantum Dots Bioconjugates for Improved Chemiluminescence Resonance Energy Transfer.

Exploration of quantum dots (QDs) as energy acceptors revolutionizes the current chemiluminescence resonance energy transfer (CRET), since QDs possess large Stokes shifts and high luminescence efficiency. However, the strong and high concentration of oxidant (typically H2O2) needed for luminol chemiluminescence (CL) reaction could cause oxidative quenching to QDs, thereby decreasing the CRET performance. Here we proposed the use of bienzyme-QDs bioconjugate as the energy acceptor for improved CRET sensing. Two enzymes, one for H2O2 generation (oxidase) and another for H2O2 consumption (horseradish peroxidase, HRP), were bioconjugated onto the surface of QDs. The bienzyme allowed fast in situ cascaded H2O2 generation and consumption, thus alleviating fluorescence quenching of QDs. The nanosized QDs accommodate the two enzymes in a nanometric range, and the CL reaction was confined on the surface of QDs accordingly, thereby amplifying the CL reaction rate and improving CRET efficiency. As a result, CRET efficiency of 30-38% was obtained; the highest CRET efficiency by far was obtained using QDs as the energy acceptor. The proposed CRET system could be explored for ultrasensitive sensing of various oxidase substrates (here exemplified with cholesterol, glucose, and benzylamine), allowing for quantitative measurement of a spectrum of metabolites with high sensitivity and specificity. Limits of detection (LOD, 3σ) for cholesterol, glucose, and benzylamine were found to be 0.8, 3.4, and 10 nM, respectively. Furthermore, multiparametric blood analysis (glucose and cholesterol) is demonstrated.