Influence of Y2O3 Content on Structural, Optical, Spectroscopic, and Laser Properties of Er3+, Yb3+ Co-Doped Phosphate Glasses

The influence of the addition of Y2O3 on the structural, spectroscopic, and laser properties of newly prepared Er, Yb-doped strontium-sodium phosphate glass was investigated. While the addition of Y2O3 has a small influence on the absorption spectra and fluorescence lifetime, it has a strong impact on the emission cross-section and on OH− content. The glasses were used as the active medium for diode-pumped laser emitting at 1556 nm. The increase in Y2O3 content leads to a significant 35% increase in laser slope efficiency up to 10.4%, but at the expense of the substantial reduction of the wavelength tunability from 82 to 54 nm.

Iron(II) reactions with glycine – suitable biomineralization model?

The reactions of Mohr’s salt with amino acid glycine in aqueous solution and aerobic conditions were studied and obtained samples consist of different compounds. The obtained products were characterized by elemental analysis, infrared spectroscopy and the iron determination also and exhibited very low organic matter content – the sum of N, C, H and S content less than 20 % and Fe content around 40 %. Prepared samples consist of iron(II) amino acid complex [Fe(glyH)(SO4)]n, known as iron food supplement (FeGS) as the only sulphur containing compound. Its content varies from 26 % up to 46 %. Ferrous glycinate was obtained in the samples collected initially after the reaction in very low content < 7 %. Iron(III) hydroxy-oxide FeO(OH) was obtained in the range 40 – 65 %. The FeO(OH) content increased with the decreasing FeGS content. Formation of inorganic FeO(OH) suggest the ongoing redox reaction under aerobic condition therefore, it is suggested as a biomineralization reaction model.

Eclogite xenoliths document water cycling at the lithosphere-asthenosphere boundary

&lt;p&gt;The amount of water stored as OH-defects in nominally anhydrous minerals in the deep mantle is poorly constrained and its direct quantification can only be accessed by the analysis of mantle xenoliths. While the vast majority of xenoliths are peridotites and minor pyroxenites, some very rare xenoliths found in kimberlite pipes display an eclogitic mineral assemblage. We investigated three eclogite xenoliths from the 128 m.y. old Robert Victor kimberlite from South Africa that display an assemblage of garnet and omphacite with two samples showing additional kyanite, suggesting low-pressure gabbroic rock as protolith. Thermobarometry estimations based on Fe-Mg partitioning between garnet and pyroxene gives temperatures of 1100-1250 &amp;#176;C. When projected on the cratonic geotherm (Griffin &amp; O&amp;#8217;Reilly 2007) an equilibrium depth of 200-210 km is obtained, confirming that these rocks come from the lithosphere-asthenosphere boundary. Therefore these fragments might be key witnesses to understand the deep cycling of water in the mantle. &lt;br&gt;&lt;br&gt;This study focuses on the H&lt;sub&gt;2&lt;/sub&gt;O quantification in the three rock-forming minerals using Fourier transform infrared spectroscopy (FTIR). Omphacite contains 50-250 ppm H&lt;sub&gt;2&lt;/sub&gt;O, kyanite contains 40-60 ppm H&lt;sub&gt;2&lt;/sub&gt;O and garnet of only one eclogite contains 40 ppm H&lt;sub&gt;2&lt;/sub&gt;O. Garnet and omphacite with the highest OH content are enriched in Ca.&lt;br&gt;&lt;br&gt;&lt;/p&gt;&lt;p&gt;The use of advanced mapping and profiling techniques enabled the investigation of the spatial repartition of the OH component in these minerals. High-resolution mapping (5.6 &amp;#181;m) of kyanite reveals diffusive gain of OH at the rim of the crystal that is interpreted as hydration during interaction with the kimberlitic melt. The OH plateau in the core of kyanite must therefore have been acquired previously, suggesting that this is residual OH that has been transported by subduction to the lithosphere-asthenosphere boundary by a once hydrated gabbroic protolith. Our results have implications for the retention of hydrogen over long timescale at the lithosphere-asthenosphere boundary and suggest that the deep cycling of water has been running since Archean times.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Griffin, W. L., &amp; O'Reilly, S. Y. (2007). Cratonic lithospheric mantle: is anything subducted?. &lt;em&gt;Episodes,&lt;/em&gt; 30(1), 43-53.&lt;/p&gt;

Sequential extraction of organosolv lignin from Chinese quince fruit: Structural features and antioxidant activities of the obtained fractions

Lignin from the Chinese quince (Chaenomeles sinensis) fruit offers a promising source of natural antioxidant for industrial applications. However, the utilization of Chinese quince fruit lignin is restricted by its inhomogeneous nature. Accordingly, Chinese quince fruit lignin was sequentially fractionated with organic solvents of increasing dissolving capacity to prepare homogeneous lignin fractions. The GPC (gel permeation chromatography) results showed that the molecular weights of lignin fractions increased from dichloromethane fraction to dioxane/water fraction. The five lignin fractions were also compared with respect to yield, carbohydrate content, thermal stability, inter-unit linkages, S/G ratios, and phenolic OH content. Among the five fractions, the ethyl acetate fraction showed a lower proportion of β-O-4′ linkages (48.4%), the highest thermal stability, the highest phenolic OH content (2.8 mmol/g), and the highest DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging index and reducing power. The high antioxidant performance of the ethyl acetate fraction implies that it can be used as a natural antioxidant. This study shows that sequential solvent fractionation of lignin can produce homogeneous fractions with enhanced antioxidant performance. In addition, it demonstrates that Chinese quince fruits are a potentially valuable natural resource.

Effects of microwave modification on the desulfurization and denitrification of activated coke

Microwave modification of activated coke is reported as a green and simple route to improve its synergistic desulfurization and denitrification. The results showed that microwave irradiation improved the specific surface area and pore volume, decreased the pore size, and activated the surface functional groups of the activated coke. Under the conditions of a microwave power of 500 W and a modification time of 30 min, the specific surface area was increased from 185.9 m2/g to 351.7 m2/g, the pore volume increased from 0.042 m3/g to 0.111 m3/g, and the characteristic peak strengths of C=C and -OH drastically increased. When the reaction temperature was 140 °C and the O2 concentration was 10% (by volume), the desulfurization and denitrification efficiency were maintained at levels greater than 90% and 80% for 30 min and 15 min, respectively. The C-O content increased, and the C=C and -OH content decreased after undergoing desulfurization and denitrification. The desulfurization and denitrification products were primarily sulfate and nitrate. This provides theoretical support for the application of microwave modified active coke in low temperature desulfurization and denitrification.

The REE-Induced Absorption and Luminescence in Yellow Gem-Quality Durango-Type Hydroxylapatite from Muránska Dlhá Lúka, Slovakia

In 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.

GaPO4 Single Crystals: Growth Condition by Hydrothermal Refluxing Method

Bulk GaPO4 is an advanced piezoelectric material operating under high temperatures according to the α-β phase transition at 970 °C. This work presents the technological development of a hydrothermal refluxing method first applied for GaPO4 single crystal growth. Crystals of 10–20 g were grown in mixtures of aqueous solutions of low- and high-vapor-pressure acids (H3PO4/HCl) at 180–240 °C (10–20 bars). The principal feature of the refluxing method is a spatial separation of crystal growth and nutrient dissolution zones. This leads to a constant mass transportation of the dissolved nutrient, even for materials with retrograde solubility. Mass transport is carried out by dissolution of GaPO4 nutrient in a dropping flow of condensed low-vapor-pressure solvent. This method allows an exact saturation at temperature of equilibrium and avoids spontaneous crystallization as well loss of seeds. Grown crystals have a moderate OH− content and reasonable structural uniformity. Moreover, the hydrothermal refluxing method allows a fine defining of GaPO4 concentration in aqueous solutions of H3PO4, H2SO4, HCl and their mixtures at set T–P parameters (T < 250 °C, p = 10–30 bars). The proposed method is relatively simple to use, highly reproducible for crystal growth of GaPO4 and probably could applied to other compounds with retrograde solubility.

A Holistic View to Develop Descriptive Sheets for Argentinean Clover and Eucalyptus Unifloral Honey

Background: Honey is a complex natural product that varies not only in sensory properties but also in chemical composition. The apiculture industry is interested in offering unifloral honey with specific palynological, physicochemical and sensory characteristics. However, to the best of our knowledge, no proper study has been reported in Argentina in this regard so far. Objective: The aim of this study was to develop descriptive sheets analyzing and compiling previous palynological, physicochemical and sensory data obtained from Argentine eucalyptus and clover unifloral honeys. Methods: The analysis included predominant and main secondary pollens; physicochemical characteristics as moisture content, acidity, ash content, electrical conductivity, fructose, glucose, maltose and sucrose, optical rotation and colour; antioxidant indicators as DPPH, TEAC, FRAC, OH; content of phenolic and flavonoids compounds and the main sensory descriptors like colour, smell, aromatic notes, sweetness and persistence. Results: The analysis was made by gathering 30 Eucalyptus honey (Eucalyptus spp.) and 55 clover honey (Trifolium sp.). Forty-one morphological pollen types were recognized. The set of physicochemical measures for honey met quality specifications for international marketing. Colour and odour intensity, higher for eucalyptus honey, were identified as the main differentiating sensory attributes. Conclusion: An holistic analysis of all these properties allows to determine quality and certification of Argentinean eucalyptus and clover unifloral honey. The intervals of variation of selected palynological, physicochemical and sensory variables gathered in the descriptive sheets allow us to decide whether or not a sample of honey can be classified as belonging to one of these floral origins.