Wt Ppm Research Articles

Separation of middle boiling trace compounds by distillation: An investigation of practical implications of complex column arrangements on an industrial methanol distillation case study

AbstractThe drive to achieve greater energy efficiencies is well‐established in the fine chemical industries with distillation processes being a key focus due to their disproportionate energy consumption totaling more than 40% of the overall plant. The objective of this paper is to specifically focus on the energy efficiency benefits that would be realized by employing intensified distillation column configurations on a high purity, multicomponent, high recovery industrial methanol distillation where a middle boiling trace ethanol component must be managed to ensure on specification production (<10 ppm wt. ethanol in product and <5 ppm impurities in bottoms). Based on technology maturity constraints, five column configurations were selected for further analysis, comprising a direct synthesis configuration, a side draw column, a Petlyuk inspired recovery column arrangement, a divided wall column, and a cut divided wall column. These configurations were then simulated on an industrial process simulator where all configurations were able to match the strict industrial product specifications and design limits. The energy usage of the column configurations was improved through a systematic analysis, and the results revealed that all intensified columns have a superior energy usage compared to the direct synthesis configuration but with the gains limited to only 3%. An unbiased consideration of the energy efficiency results, together with other external factors including cost of capital and operability, shows that the recovery column configuration would be the most practical choice despite the presence of the divided wall column configuration which represents a greater level of intensification and integration.

Phlogopite-Olivine Nephelinites Erupted During Early Stage Rifting, North Tanzanian Divergence

The North Tanzanian Divergence (NTD, eastern branch of the East African Rift) corresponds to an early stage of continental breakup. In the southern NTD, two quaternary volcanoes of the Manyara-Balangida rift (Labait, Kwaraha) have erupted primary nephelinite lavas (Mg# = 79–57) that allow characterization of their deep mantle source and the alkaline magmas that percolated through the lithosphere during rift initiation. Nephelinites are olivine- and clinopyroxene-rich, and contain up to 4 vol% magmatic phlogopite that crystallized as a liquidus phase with olivine and clinopyroxene. The presence of hydrous mineral (phlogopite) phenocrysts in Kwaraha and Labait lavas strongly suggests that the alkaline melts were H2O-bearing at the time of phlogopite crystallization (1.57–2.12 wt% H2O in phlogopite), demonstrating that phlogopite may have influenced the partitioning of water between the silicate melt and anhydrous silicate minerals (<1 ppm wt H2O clinopyroxene, 1–6 ppm wt H2O in olivine). Geochemical modeling indicates that the nephelinite magmas resulted from a low degree of partial melting (0.2–1%) of a carbonate-rich (0.3%) garnet peridotite containing ∼2 vol% phlogopite. We estimate the depth of partial melting based on primary melt compositions and empirical relations, and suggest that melting occurred at depths of 110–130 km (4 GPa) for craton-edge lavas (Kwaraha volcano) and 150 km (5 GPa) for on-craton lavas (Labait volcano), close to or below the lithosphere-asthenosphere boundary in agreement with the presence of deep refractory mantle xenoliths in Labait lavas. The depth of melting becomes gradually deeper toward the southern NTD: highly alkaline magmas in the north (Engaruka-Natron Basin) are sourced from amphibole- and CO2-rich peridotite at 75–90 km depth, whereas magmatism in the south (south Manyara Basin) is sourced from deep phlogopite- and CO2-rich garnet-peridotite beneath the Tanzania craton (e.g., at the on-craton Labait volcano). Percolation of deep asthenospheric CO2-rich alkaline magmas during their ascent may have produced strong heterogeneities in the thick sub-continental lithospheric mantle by inducing metasomatism and phlogopite crystallization in glimmerite lithologies.

Quantitative PIXE analyses of trace Ti in single fluid inclusions in quartz from Tsushima granite

The trace element content of single fluid inclusions in quartz from Tsushima granite in Japan was determined with particle-induced X-ray emission (PIXE) to investigate the chemical features of Ti in hydrothermal fluids derived from granites. Most of the fluid inclusions were polyphase and vapor-rich fluid inclusions, and both types contained Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Ge, Br, Rb, Sr, Ba, and Pb. Concentrations of Ti were of up to a few tens ppm wt Ti for polyphase inclusions and up to one hundred ppm for vapor-rich fluid inclusions. The Ti content indicated the possibility of transportation of a certain amount of Ti by granitic hydrothermal fluids.

Water in coesite: Incorporation mechanism and operation condition, solubility and P-T dependence, and contribution to water transport and coesite preservation

A series of coesite, coexisting with or without a liquid phase, was synthesized in the nominal system SiO2–H2O at 800–1450 ​°C and 5 ​GPa. Micro-Raman spectroscopy was used to identify the crystalline phase, electron microprobe and LA-ICP-MS were employed to quantify some major and trace elements, and unpolarized FTIR spectroscopy was applied to probe the different types of hydrogen defects, explore water-incorporation mechanisms and quantify water contents. Trace amounts of Al and B were detected in the coesite. Combining our results with the results in the literatures, we have found no positive correlation between the Al contents and the “Al”-based hydrogen concentrations, suggesting that previously proposed hydrogen-incorporation mechanism H+ ​+ ​Al3+ ↔ Si4+ does not function in coesite. In contrast, we have confirmed the positive correlation between the B contents and the B-based hydrogen concentrations. The hydrogen-incorporation mechanism H+ ​+ ​B3+ ↔ Si4+ readily takes place in coesite at different P-T conditions, and significantly increases the water content at both liquid-saturated and liquid-undersaturated conditions. For the SiO2–H2O system, we have found that type-I hydrogarnet substitution plays a dictating role in incorporating water into coesite at liquid-saturated condition, type-II hydrogarnet substitution contributes significantly at nearly dry condition, and both operate at conditions in between. The water solubility of coesite, as dictated by the type-I hydrogarnet substitution, positively correlates with both P and T, cH2O ​= ​−105(30) ​+ ​5.2(32) ​× ​P ​+ ​0.112(26) ​× ​T, with cH2O in wt ppm, P in GPa and T in °C. Due to its low water solubility and small fraction in subducted slabs, coesite may contribute insignificantly to the vertical water transport in subduction zones. Furthermore, the water solubility of any coesite in exhuming ultra-high pressure metamorphic rocks should be virtually zero as coesite becomes metastable. With an adequately fast water-diffusion rate, this metastable coesite should be completely dry, which may have been the key factor to the partial preservation of most natural Coe. As a byproduct, a new IR experimental protocol for accurate water determination in optically anisotropic nominally anhydrous minerals has been found. Aided with the empirical method of Paterson (1982) it employs multiple unpolarized IR spectra, collected from randomly-orientated mineral grains, to approximate both total integrated absorbance and total integrated molar absorption coefficient. Its success relies on a high-level orientation randomness in the IR analyses.

Variable extent of dehydration of clinopyroxene megacrysts from Gezi volcano of Inner Mongolia

Mineral phenocrysts/megacrysts convey important information about deep magmatic evolution and volcanic eruption especially with respect to magmatic water content. Clinopyroxene (cpx) is generally considered to be less susceptible to diffusive hydrogen loss than olivine and orthopyroxene. We analyzed hydrogen concentration profiles alongside major and trace element compositions of a suite of cpx megacrysts (1–4 cm in size) hosted in basanitic scoria from the Gezi volcano, central Inner Mongolia of north China. The anhydrous composition within each megacryst is homogeneous, but comparison between different grains shows clear elemental covariation, suggesting that these cpx megacrysts progressively crystallized from a common parental magma. The cpx megacrysts contain hydrogen contents in the range of 0–410 wt ppm H2O at their cores, and some of them show a smooth decrease of hydrogen from the core to the rim. Those with the highest hydrogen contents (290–410 wt ppm H2O) have long plateau at the core, in contrast with long dehydration profiles and no plateau in some low-hydrogen megacrysts. These observations suggest that the cpx megacrysts experienced variable extent of dehydration during volcanic eruption, arising from variable H diffusivity probably associated with differences in the composition and microstructure of cpx megacrysts. Cpx megacrysts with the lowest degree of dehydration and good diffusion profiles are the most informative. Their plateau hydrogen contents at the core are used to infer ~2 wt% H2O in the parental magma. Quantitative modeling of the diffusion profiles at the rim yields a dehydration duration of 3–28 h, suggesting an ascent rate of 1–6 m/s for the host basanitic magma.

Synthesis of sugar‐based macromolecules via sono‐ATRP in miniemulsion

Ultrasound‐mediated atom transfer radical polymerization (sono‐ATRP) in miniemulsion media is used for the first time for the preparation of complex macromolecular architectures by a facile two‐step synthetic route. Initially, esterification reaction of sucrose or lactulose with α‐bromoisobutyryl bromide (BriBBr) is conducted to receive multifunctional ATRP macroinitiators with 8 initiation sites, followed by polymerization of n‐butyl acrylate (BA) forming arms of the star‐like polymers. The brominated lactulose‐based molecule was examined as an ATRP initiator by determining the activation rate constant (ka) of the catalytic process in the presence of a copper(II) bromide/tris(2‐pyridylmethyl)amine (CuIIBr2/TPMA) catalyst in both organic solvent and for the first time in miniemulsion media, resulting in ka = (1.03 ± 0.01) × 104 M−1 s−1 and ka = (1.16 ± 0.56) × 103 M−1 s−1, respectively. Star‐like macromolecules with a sucrose or lactulose core and poly(n‐butyl acrylate) (PBA) arms were successfully received using different catalyst concentration. Linear kinetics and a well‐defined structure of synthesized polymers reflected by narrow molecular weight distribution (Mw/Mn = 1.46) indicated 105 ppm wt of catalyst loading as concentration to maintain controlled manner of polymerization process. 1H NMR analysis confirms the formation of new sugar‐inspired star‐shaped polymers.

Carbon content driven high temperature γ-α2 interface modifications and stability in Ti–46Al–4Nb intermetallic alloy

The effect of carbon addition on the microstructure modifications and hardness response of a two-phase lamellar Ti–46Al–4Nb intermetallic alloy was studied. The alloy was heat treated as to have an initial tow-phase refined lamellar microstructure consisting of α2 laths and γ phase characterized by nanometric wide twinning. The effect of carbon in solid solution in the α2 phase and the onset of the H–Ti2AlC phase precipitation within the γ phase was addressed. A threshold carbon limit of C ≅ 3000 wt ppm was identified as lower limit solute concentration for the precipitation initiation of the H phase particles. The major alloy hardening factors were identified as the refined interlamellar spacing, the fine twinning and the amount of carbon in solid solution. The role of H phase formation on the alloy hardening with carbon content was addressed and it was essentially such to induce a hardening saturation effect.

Size-dependent biological effects of copper nanopowders on mustard seedlings

Correlation between the size of copper nanoparticles and effects they produce on white mustard seedlings were studied in the paper. Copper nanopowders with average particle sizes of 45 and 200 nm with concentrations of 0.01–1000 wt ppm of seeds were used to treat white mustard seeds. Nonlinear dose effects were displayed by copper nanopowders obtained by chemical synthesis with the particle size of 35-60 nm. For 45 nm nanoparticles the highest biological activity with regard to germinating energy, 3-day stem and root weight was registered at 5.0 wt ppm concentration, while for root length and weight of the 7-day stems the 1.0 wt ppm concentration had the most pronounced effect. Copper submicron powder with average particle size of 200 nm displayed some effect only after 7th day of the experiment at high concentrations (from 100 to 1000 wt ppm) according to the measurements of length and weight of the seedlings. The obtained results can be used in the development of copper nanoparticles-based preparations for pre-sowing treatment of seeds.

A földköpeny reológiai kutatása: mennyiségi Fourier transzformációs infravörös spektrometria alkalmazása egy Persány hegységi xenolit példáján

A felsőköpenyből származó xenolitok kőzettani és geokémiai vizsgálatával közvetlen ismeretekhez juthatunk a litoszféra fizikai és kémiai állapotáról. Ezen információk birtokában kiszámíthatók a xenolitok által jellemzett köpenylitoszféra legfontosabb geofizikai tulajdonságai (pl. szeizmikus hullámsebesség, fajlagos vezetőképesség, effektív viszkozitás). Ezek a fizikai jellemzők meghatározók a geofizikai mérések eredményének értelmezésében, és így a kutatott régió geodinamikai fejlődésének megértésében. Jelen tanulmányban azt mutatjuk be, hogy akár nyomnyi mennyiségű „víz” (helyesebben szerkezeti hidroxil) jelenléte a földköpeny névlegesen vízmentes ásványaiban (röviden NAM elegyrészek az angol „Nominally Anhydrous Minerals” kifejezés alapján) milyen kiemelkedő jelentőséggel bír a litoszféra fizikai viszonyaira és hogyan reagál a rendszer kémiai összetételére. A felsőköpeny geokémiai és geodinamikai kutatásában alkalmazott spektrometriai technikák közül a Fourier transzformációs infravörös spektrometria (FTIR) a NAM elegyrészek szerkezeti hidroxil-tartalmának tanulmányozásával a kőzetek fizikai viselkedéséről (pl. olvadási hőmérséklet, deformálhatóság, fajlagos vezetőképesség stb.) és bizonyos kémiai tulajdonságairól (H-tartalom) ad képet. Kísérleti kőzettani eredmények alapján a H+ töltéskompenzáló kationként vakanciákba önállóan, vagy csatolt helyettesítést létrehozva más kationokkal (pl. Al3+ vagy Ti4+) együtt tud a NAM elegyrészekbe beépülni. A vakanciák esetében a H+ valamelyik koordináló oxigénhez csatlakozva OH- (szerkezeti hidroxil) gyököt hoz létre. Ritkán a H+ önállóan, intersticiális helyzetben vagy Li+- és Na+-hoz csatlakozva szerkezeti hidroxil formájában is előfordulhat a rácsközi térben. A beépülés jellege függ a rendszer összetételétől (pl. Ti-tartalom), az oxigén, H2O és SiO2 aktivitásától, az oxigén fugacitástól és a nyomástól. A beépülés módján kívül a NAM elegyrész pontos szerkezeti hidroxil tartalmát is meg lehet határozni mikro-FTIR spektrometriával. A szerkezeti hidroxil koncentrációt konvencionálisan molekuláris víz egyenértékben és ppm tömegrészben vagy mol %-ban fejezzük ki. A nem poláros mikro-FTIR módszer térnyerése az utóbbi időben jelentős áttörést hozott, hiszen a kis szemcseméretű (&lt;0,7 mm) természetes és kísérleti kőzetek ásványainak elemzésére is lehetőség nyílt, amelyre a tradicionálisan megbízhatónak gondolt poláros mikro-FTIR módszer nem adott módot. Tanulmányunk egyik célja, hogy részletes áttekintést adjunk a mikro-FTIR alkalmazásáról a NAM szerkezeti hidroxil tartalmának vizsgálatához.A nem poláros mikro-FTIR módszert ma már világszerte alkalmazzák, a Kárpát-Pannon régió felsőköpeny kutatásában is nagy szerepet kap. Alkalmazását a Persány-hegységi Vulkáni Terület felső-köpeny xenolitjain mutatjuk be, összehasonlítva korábbi munkákkal a Kárpát-Pannon régióból, kiemelve az eredmények felhasználhatóságát a geofizikai adatok értelmezéséhez és így a Kárpát-Pannon régió geodinamikájának jobb megértéséhez. A persány-hegységi xenolitra kapott geofizikai eredmények (szeizmikus hullámterjedési sebesség, fajlagos vezetőképesség) és effektív viszkozitás nagy hasonlóságot mutat a Stájer-medence xenolitjaival, ami a két terület hasonló geodinamikai helyzetének köszönhető. A Nógrád-Gömör vulkáni terület xenolitjai eltérő jellemvonásokat mutatnak.

High-Temperature Evolution of Point Defect Equilibria in Hydrous Forsterite Synthesized at 1100 °C and up to 4 GPa

Water distribution in the deep Earth represents one of the most important topics in the field of geodynamics due to its large impact on the physical and chemical properties of the Earth’s mantle, such as electrical conductivity, seismic anisotropy, diffusion, and rheology. In this study, we synthesized hydrous forsterite at 1100 °C and up to 4 GPa with either a piston-cylinder or multianvil apparatus. As a starting material, we used synthetic forsterite, unbuffered by SiO2, obtained by thermo-mechanical activation of talc and magnesium carbonate hydroxide. Hydration was carried out using liquid H2O as hydrogen source. Samples were polycrystalline in an effort to distribute H2O throughout the sample both rapidly and homogeneously. Using the Paterson calibration, we observed total water content concentrations ranging between 100 and 500 ppm wt H2O. Multiple absorption bands are found in the frequency range between 3400 and 3650 cm−1, identifying at least seven peaks in all samples. Vibrational bands were centered at 3476, 3535, 3550, 3566, 3578, 3605, and 3612 cm−1, in good agreement with experimental studies conducted on both hydrous forsterite and single crystals of olivine. The stronger OH stretching peaks can be attributed to vibrational modes associated with the hydrogarnet defect 4 H Si x in which four protons occupy a vacant tetrahedral site. None of the OH bands observed are found at frequencies associated with hydrogen occupying vacant octahedral sites. High-temperature FTIR spectroscopy was used to evaluate the evolution of IR spectra as a function of temperature, up to 500 °C. The complete reversibility of peak absorption vs. temperature in the OH stretching region confirms that no water loss occurred during heating. We observe an overall a decrease in total absorption with increasing temperature, and a prominent decrease in the relative intensities of the higher frequency bands (&gt;3600 cm−1) with respect to lower frequency bands. We have assigned a series of equilibrium expressions based on the variation of relative peak areas with temperature and find that enthalpies of these processes range between 0.047–0.068 eV (4.5–6.5 kJ/mol), very low in comparison to activation energies observed for electrical conduction in hydrous olivine. Major changes in the vibrational spectrum are expected to be related to configurational changes of the same fully protonated hydrogarnet defect species. However, the complexity of the FTIR spectra may also be related to partially protonated defects, such as the associate defect 3 H Si ′ + H i • generated by a dissociation reaction of the hydrogarnet species.

Boron in Heat‐Treatable Steels: A Review

The science and technology of boron addition to heat‐treatable steels are explained. The aim is to address the following: How to add boron to steel (i.e., the manufacturing aspects of boron addition to steel)? What precautions are necessary when alloying boron to steel, in terms of composition (mainly nitrogen, aluminum, and titanium contents), processing and heat treatment (i.e., material and process robustness and reproducibility for a consistent steel quality)? Where does boron go in steel (i.e., the state of boron, interstitial or substitutional solute, precipitate or a complex with other alloying elements; as well as the location of boron, i.e., dissolved as a solute in the grain or segregated at the grain boundary)? Which characterization methods are suitable for the detection of the very small amounts of boron (&lt;30 wt ppm) in heat‐treatable steels? What does boron do in steel (i.e., its effect on hardenability and mechanical properties, specifically impact toughness)? How does it do and what it does (i.e., the physical mechanism by which it influences the properties)? How much boron is really required to achieve the desired properties in heat‐treatable steels (i.e., recommendations for the optimum boron content)?

Water Concentration in Single‐Crystal (Al,Fe)‐Bearing Bridgmanite Grown From the Hydrous Melt: Implications for Dehydration Melting at the Topmost Lower Mantle

AbstractHigh‐quality single‐crystals of (Al,Fe)‐bearing bridgmanite, Mg0.88 Fe3+0.065Fe2+0.035Al0.14Si0.90O3, of hundreds of micrometer size were synthesized at 24 GPa and 1800 °C in a Kawai‐type apparatus from the starting hydrous melt containing ~6.7 wt% water. Analyses of synthesized bridgmanite using petrographic microscopy, scanning electron microscopy, and transmission electron microscopy show that the crystals are chemically homogeneous and inclusion free in micrometer‐ to nanometer‐spatial resolutions. Nanosecondary ion mass spectrometry (NanoSIMS) analyses on selected platelets show ~1,020(±70) ppm wt water (hydrogen). The high water concentration in the structure of bridgmanite was further confirmed using polarized and unpolarized Fourier‐transform infrared spectroscopy (FTIR) analyses with two pronounced OH‐stretching bands at ~3,230 and ~3,460 cm−1. Our results indicate that lower‐mantle bridgmanite can accommodate relatively high amount of water. Therefore, dehydration melting at the topmost lower mantle by downward flow of transition zone materials would require water content exceeding ~0.1 wt%.

Electrical conductivity of hydrous silicate melts: Implications for the bottom-up hydration of Earth's upper mantle

The upwelling of the hydrous mantle transition zone triggers dehydration-induced partial melting atop the 410-km discontinuity. Here we investigate the electrical conductivity of hydrous silicate melts in the 200-400 km depth range and explore whether melting at the 410-km depths is responsible for the hydration of the upper mantle. Our experimental electrical conductivity data demonstrate that the mantle at 180-350 km depths is mostly melt free, confirming the H2O under-saturated conditions. However, the residual mantle from partial melting atop the 410-km discontinuity may contain various possible amounts of water according to the initial mantle transition zone and melt concentrations. This residual H2O could contribute to the hydration of the upper mantle either through diffusion or material replacement by upwelling. Our calculations suggest that the diffusion may not be responsible for the hydration of the upper mantle to present H2O concentration of 50–200 ppm wt. Melting of the upwelling mantle transition zone with less than 1500 ppm wt. H2O produces residual peridotites with ∼ 200 ppm H2O at the 410-km discontinuity. Continuous upwelling of such hydrous residues would gradually replace the dry upper mantle with depleted residual hydrous peridotites in less than 260 Ma. In this study, we propose a bottom-up hydration mechanism for the Earth's upper mantle driven by dehydration-melting at the 410-km discontinuity. The hydrous partial melting at the top of the asthenosphere appears to be a consequence of H2O saturation in the upwelling residual peridotites.

New approach for preparation of high-purity sulfide-germanium glasses doped with praseodymium

It has been established that rare earth elements (REE), as alloying additives, are a significant source of hydrogen and oxygen impurity in glasses of Ge &#x2013; S and Ge &#x2013; As &#x2013; S systems. A method has been developed that includes loading germanium in the form of monosulfide and high-temperature annealing of REE and their compounds in sulfur vapor, reducing content of absorbing impurities in sulfide-germanium glasses. Samples of especially pure glasses of Ge42.5S57.5 and Ge35As10S55 composition doped with praseodymium up to 1450&#x2005;ppm(at) were prepared. The impurity content of hydrogen and oxygen in the form of SH-groups and Ge&#x2013;O in the best glass samples was 0.02&#x2013;0.06&#x2005;ppm(wt) and &lt;0.1&#x2013; 0.2&#x2005;ppm(wt), respectively. The absorption coefficients and the absorption cross section were determined for various energy states of the Pr3&#x002B; ion in Ge35As10S55 glass. The luminescence intensity of Pr3&#x002B; ions in the spectral ranges 2.0&#x2013;2.8 and 3.5&#x2013;5.8&#x2005;&#x00B5;m in Ge42.5S57.5 glasses is by 3 orders of magnitude higher than in Ge35As10S55 glasses.

Upper Mantle Melt Distribution From Petrologically Constrained Magnetotellurics

AbstractThree parameters: temperature, hydrogen content, and the presence of partial melt, are the dominant controls on the rheology of the convecting upper mantle. As such, they determine the dynamics that control plate tectonics and continental evolution. Since hydrogen depresses the peridotite solidus temperature, these parameters are strongly linked petrologically. We have developed a genetic algorithm code to statistically assess the likelihood that a section of upper mantle contains partial melt. This code uses magnetotelluric observations and petrological constraints on composition and solidus temperatures and allows for uncertainties in the geotherm and the electrical conductivity structure. We have applied this code to the convecting upper mantle beneath (1) a stable continent (the Superior Craton); (2) a hot spot (Tristan da Cunha); (3) stable, old oceanic lithosphere (the northwest Pacific Ocean); and (4) young oceanic lithosphere (adjacent to the East Pacific Rise). Results show that the volume of melt in the convecting upper mantle is heterogeneous. The highest melt proportions are beneath the hot spot while little to no melt is required in the other regions. All regions show low water contents (generally &lt;50 wt ppm in olivine) in the shallow convecting upper mantle, making it unlikely that water causes a large or sharp viscosity contrast between the lithosphere and the convecting mantle. Results differ significantly for different experimental olivine hydrogen conductivity models, highlighting the importance of reconciling these experimental constraints.

Preparation of Ge20Se80 glasses with low hydrogen and oxygen impurities content for middle IR fiber optics

The method for preparation of high-purity GeSe glasses with the low content of hydrogen and oxygen impurities is developed. The method includes following stages: selenium purification by chemical-distillation technique; passing selenium vapors over a mixture of Ge batch and 2 wt% of Al for loading the components into the reactor; glass melting, quenching and cooling. Optical losses in the unclad fiber did not exceed 1 dB/m in the spectral ranges 2.0–4.3 μm and 4.8–7.8 μm; the minimum optical losses were 0.77 dB/m at 5.6 μm. The fiber is characterized by the record low content of oxygen, chemically bound to germanium, which is 0.013 ± 0.002 ppm(wt), the concentration of hydrogen in the form of SeH groups is 1.77 ± 0.12 ppm(at). The silica reactor is shown to be the source of impurities of hydrogen, metals and heterogeneous particles in GeSe glasses.

Time variations in the chemical and isotopic composition of fumarolic gases at Hakone volcano, Honshu Island, Japan, over the earthquake swarm and eruption in 2015, interpreted by magma sealing model

Definite increases in the components ratios of CO2/H2O, CO2/H2S, CO2/CH4 and He/CH4 were observed at the fumarolic gases from Owakudani geothermal area located at the center of Hakone volcanic caldera (Honshu Island, Japan), synchronized with the earthquake swarm in 2015. Such variations were due to the dominance of a magmatic component over a hydrothermal component, suggesting the earthquake swarm was produced by the injection of magmatic gases into the hydrothermal system. The CO2/H2O ratio of magmatic gas was estimated to be 0.0045 before the earthquake swarm, which increased up to 0.013 during the earthquake swarm, likely produced by the pressurization of magma as a result of magma sealing where the pressure increment in magma was estimated to be 3% to the lithostatic pressure. The H2O and CO2 concentration in magma were estimated to be 6.3 wt% and 20 wt ppm, respectively, assuming a temperature 900 °C and a rhyolitic composition. In May 2015, a few months prior to the earthquake swarm in May 2015, a sharp increase in the Ar/CO2 and N2/He ratios and a decrease in the isotopic ratio of H2O were observed at the fumarolic gas. The invasion of air into the hydrothermal system increased the Ar/CO2 and N2/He ratios. The decrease in the isotopic ratio of H2O was induced by partial condensation of H2O vapor.

Zircon solubility in silicate melts: New experiments and probability of zircon crystallization in deeply evolved basic melts

Experiments on zircon crystallization from synthetic melts have been made at 1 atm in a wide range of non-granitic compositions with index M = (Na + K + 2 Ca)/(Al∙Si) varying from 0 (no alkalis, no CaO) to 3.5 and temperature range 1150–1500 °C, with the aim of obtaining an extended data set on the zircon solubility in melts. Concentration of Zr in experimental glasses, measured with EMPA varied from 4540 to 61,370 wt ppm. Separate effects of TiO2, Fe oxides and SiO2 on the Zr solubility have been evaluated. The newly obtained subset, consisted of 67 experimental points was combined with the 62 data points from the literature to derive an empirical equation relating Zr solubility with silicate melt composition and absolute temperature T: log Zr (ppm) = 4.322·B − 4338.8/T(K) + 6.456, where B is the following ratio of the oxide mole fractions in the melts: B = 0.14(XTiO2/XSiO2) + 1.3(XCaO/XSiO2) + 1.5(XNa2O/XSiO2) − 4.5(XK2O/XSiO2) − 2.7(XAl2O3/XSiO2)2 + (XMgO/XSiO2)2 − 3.7(XCaO/XSiO2)2 + 75(XK2O/XSiO2)2. The new equation predicts log (Zr, ppm) with a standard error of 0.104, which is equivalent to ca 24% error for the entire Zr concentration range covered by experiments (155–61,370 ppm of Zr) and performs much better on the dataset than the previously published equations. It is particularly suited for evaluating a likelihood of zircon crystallization from evolving basaltic magmas. Such evaluation done on the well constrained experiments from the literature indicates that even near-solidus crystallization of zircon in deeply evolved initially basaltic melts is highly unlikely in dry liquids although cannot be completely ruled out and may even be quite plausible in the water-containing ones.

A systematic study and effect of PLA/Al2O3 nanoscaffolds as dental resins: mechanochemical properties

One of the major and important challenges in dental composite resin and restoration is the mechanical performance and property of materials. Nanotechnology can produce nanoscale materials that are used in dentistry to help stabilize and strengthen the dentistry. In this work, we study the synthesis and characterization of PLA/Al2O3 nanoscaffold in different conditions such as concentration, temperature, pH, microwave power and irradiation time. PLA/Al2O3 nanoscaffolds were prepared by a micelle-assisted hydrothermal method. Durability, stability and biodegradable nature of nanopolymers have created the much-applied potential for using this structures in many fields such as dental resin composites. Products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), Fourier transformed infrared spectrum (FT-IR), Dynamic light scattering (DLS) and atomic force microscopy (AFM). The synthesis factors were designed by Taguchi technique to control the process systematically. It was found that the intermolecular crosslinks between PLA and Al2O3 nanoparticles cause significant improves in the mechanical properties of PLA/Al2O3 nanoscaffold as dental nanocomposites. The flexural strength (88.0 MPa), modulus (7.5 GPa) and compressive strength (157.2 MPa) were calculated for PLA/Al2O3 nanoscaffolds loaded in Heliomolar Flow composite resins at 80 ppm (wt) concentration.

Selection Process of Phytochemicals and Efficacy of Thymol, Eugenol and Calcium Ferulate on Heterotrophic Plate Count Bacteria in Water

Water samples of Lahore Canal have been tested for log reduction of heterotrophic plate count microorganisms in the presence of three selected phytochemicals: thymol, eugenol and freshly prepared calcium salt of ferulic acid. Thymol results in about 0.9 log10 reduction (at 80 min contact time), 1.2 log10 reduction (at 90 min contact) and 2.6 log10 reduction (contact time: 60 min) for 75, 150 and 300 ppm wt./wt. phytochemical in water sample respectively. Eugenol at 150 and 300 ppm is as good as thymol for log10 reduction, but not at 75 ppm. Calcium ferulate does not significantly reduce the heterotrophic plate count microorganisms at the three tested concentrations. Contact time is found crucial for optimum reduction of microorganisms. Further studies have been carried out for thymol at 50 ppm. It is observed that thymol results in 0.9 log10 reduction at pH 9.5 and 30oC. At this concentration and at 13oC and 20oC, significant decrease in heterotrophic plate count is not observed at either pH 4.5, 7.0, and 9.5. Contact time is again important for inactivating the microorganisms. Statistical analysis is made to evaluate differences between the phytochemical-time in concentration treatment groups and pH-time in the temperature treatment groups. Two linear models of thymol reduction of heterotrophic plate count microorganisms are developed to study the relationships between the variables responsible for inactivation. Where experimental data is not available, software PASS, GUSAR, EPI Suite and Marvin Sketch are used to predict antimicrobial properties, toxicity and water solubility. Based on these criteria, affordability and aesthetics, the final selection of phytochemicals is made.