Measurement of 2-ethyl-1-hexanol emitted from flooring materials and adhesives

It has been reported that 2-ethyl-1-hexanol (2E1H) was emitted through hydrolysis between di-2-ethylhexyl phthalate used as plasticizer in flooring material and moisture generated from a strongly alkaline material such as concrete slab. The purpose of this study was to clarify the relationship between diffusion of 2E1H in flooring material and 2E1H emission rate from floor surface. In this study, we measured 2E1H emitted from floor paper, poly(vinyl chloride) (PVC) tile, cushion floor and carpet for 200,?days and effective diffusion coefficients for 2E1H in various flooring materials were measured. Effective diffusion coefficients of 2E1H for cushion floor and PVC tile were 115?×?10^?9 and 7.8?×?10^?9 m²/s, respectively. Emission rate of 2E1H emitted from flooring material significantly depends on the kind and shape of flooring materials and was influenced by the effective diffusion coefficient for 2E1H of flooring material. Emission rates of 2E1H from floor surface varied with the amount of 2E1H and resin present in the adhesive. When carpet was attached to the flooring material with high water content using adhesive, emission of 2E1H significantly increased. The results show that primary and secondary emissions of 2E1H from the adhesive influence the emission rate of 2E1H for flooring material.     

Chemical Composition and Oxidative Stability of Selected Plant Oils

Scientific data on the oxidative stability of borage oil, Camelina sativa oil, linseed oil, evening primrose oil and pumpkin seed oil are scarce. Chemiluminescence (CL) methods most commonly used to determine the oxidative stability of oils include measurement of hydroperoxide, intensity of light emitted during the accelerated oxidation process performed at high (>100 °C) temperatures or assisted by forced flow of air/oxygen through the sample. The aim of this study was to investigate the chemical composition and oxidative stability of selected vegetable oils available on the Polish market. Oxidative stability was determined using a fast, novel chemiluminescence-based method, in which light emitted during oxidation process conducted at 70 °C in the presence of some catalyzing Fe²⁺ ions is measured. A reaction of the applied type has not been reported so far. High contents of tocopherols and phytosterols were found in the analyzed oil samples. Oxidative stability of the samples was in most cases higher than the stability of refined rapeseed oil, a relatively stable substance from the oxidation point of view.     

Binary component sorption of Cu(II) and Pb(II) with activated carbon from Eucalyptus camaldulensis Dehn bark

The objective of this work is to illustrate the potential in the use of activated carbon in the binary component sorption of copper and lead ions. Eucalyptus bark was used as a precursor for the activated carbon which was prepared through the phosphoric acid activation process. This activated carbon was then used for the sorption of copper and lead ions. The quantity of the metal ions in the solution was measured with the Flame & Graphite Furnace Atomic Adsorption Spectrophotometer. The results indicated that the optimal pH for sorption was 5. The maximum sorption capacities for Cu(II) and Pb(II) were 0.45 and 0.53 mmol g⁻¹. Carboxylic, amine and amide groups were found to involve in the sorptions of Cu(II) and Pb(II). A major mechanism for the uptake of both heavy metals was proven not to be ion exchange but adsorption. In binary component sorptions, activated carbon still could sorb Pb(II) in a greater amount than Cu(II). However, the presence of the secondary metal ions suppressed the sorption of the primary metal ions. There seemed to have a linear inverse dependency between the sorption capacity and the concentration of the secondary metal ion.     

Long-Range Diffusion of K Promoter on an Ammonia Synthesis Catalyst Surface—Ionization of Excited Potassium Species in the Sample Edge Fields

The potassium ions K⁺which diffuse out to the surface from the K promoted ammonia synthesis iron catalyst material do not desorb from there but diffuse rapidly along the surface until they reach the edges of the sample. This is shown by angular distributions of the ion emission at the normal operating temperatures of 900–1100 K. The ionic emission at low field strengths, of the order of 2–50 V cm⁻¹, has a minimum or even a zero signal in the direction of the surface normal. Instead of desorbing from the surface, the ions interact strongly with the surface and give electronically excited states K^*on the surface, which diffuse rapidly along the surface over a distance of several millimeters to the edges of the sample. A detailed model is proposed for this process, based on recent kinetic results. At the edges, ions are formed in the stronger electric field just outside the surface giving lobes along the surface. With the highest field strengths used, these lobes are transformed into strongly peaked distributions at 45–70° from the normal, with a strong minimum in the normal direction. From the open surface, only clusters K_nand neutral atoms K can be emitted. Trajectory calculations show that ions, which are emitted from the edges of the sample with higher then thermal energy, appear in the experimentally observed angular range. Their excess energy may be derived from the work function difference between the catalyst sample and its Ta holder.     

Eu3+-activated double perovskite Sr3MoO6 phosphors with excellent color purity for high CRI WLEDs and flexible display film

A red-emitting Eu³⁺-activated double perovskite Sr₃MoO₆ phosphor material was successfully synthesized by a high-temperature solid-state reaction. Upon 353 and 467 nm excitations, the prepared phosphors exhibited the feature emission properties of Eu³⁺ ions with the corresponding characteristic electronic transitions. The concentration quenching of Eu³⁺ ions was found at 30 mol% and the quadrupole-quadrupole interaction was dominant in quenching process. The chromaticity coordinates for the optimal doping concentration of Eu³⁺ ions under the 353 and 467 nm excitations were in the pure red region, while the color purity was calculated to be about 94.536 and 94.780%, respectively. The superior luminescence properties of the red-emitting Sr₃MoO₆:0.3Eu³⁺ phosphor were achieved and with further blending with commercial phosphors, the white light-emitting diode (WLED) devices were fabricated for practical application. The fabricated WLED device based on 385 nm near-ultraviolet (NUV) chip revealed the color-rendering index and color temperature values of 90.96 and 6381 K, respectively. And the soft polydimethylsiloxane film emitted the pure red region under NUV light. These results suggest that this kind of material could be a promising red-emitting phosphor for WLEDs and flexible display film.     

Dynamics of ion beam modification of polymer films

Thin polymer films were irradiated in a high vacuum environment with energetic (～2 MeV) ions. The emitted molecular species were studied with a quadrupole mass spectrometer during bombardment. The emitted species are predominantly small molecules. The efficiency of emission depends strongly upon the electronic energy loss of the incident ions in the film and, hence, upon the velocity and atomic number of the incident ion. The emission efficiency of all species decreases with increasing damage in the film. By pulsing the ion beam, the time dependence of irradiation induced emission of molecular species from the films has been studied. Emission delays of hundreds of milliseconds are observed in some cases. These delays are found to depend upon the emitted species as well as the host film and seem to be associated with diffusion of the species in the films.     

Dominant Mechanisms that Shape the Airborne Particle Size and Composition Distribution in Central California

The size and composition of ambient airborne particulate matter is reported for winter conditions at five locations in (or near) the San Joaquin Valley in central California. Two distinct types of airborne particles were identified based on diurnal patterns and size distribution similarity: hygroscopic sulfate/ammonium/nitrate particles and less hygroscopic particles composed of mostly organic carbon with smaller amounts of elemental carbon. Daytime PM₁₀ concentrations for sulfate/ammonium/nitrate particles were measured to be 10.1 μ g m^?3, 28.3 μ g m^?3, and 52.8 μ g m^?3 at Sacramento, Modesto and Bakersfield, California, respectively. Nighttime concentrations were 10–30% lower, suggesting that these particles are dominated by secondary production. Simulation of the data with a box model suggests that these particles were formed by the condensation of ammonia and nitric acid onto background or primary sulfate particles. These hygroscopic particles had a mass distribution peak in the accumulation mode (0.56–1.0 μ m) at all times. Daytime PM₁₀ carbon particle concentrations were measured to be 9.5 μ g m^?3, 15.1 μ g m^?3, and 16.2 μ g m^?3 at Sacramento, Modesto, and Bakersfield, respectively. Corresponding nighttime concentrations were 200–300% higher, suggesting that these particles are dominated by primary emissions. The peak in the carbon particle mass distribution varied between 0.2–1.0 μ m. Carbon particles emitted directly from combustion sources typically have a mass distribution peak diameter between 0.1–0.32 μ m. Box model calculations suggest that the formation of secondary organic aerosol is negligible under cool winter conditions, and that the observed shift in the carbon particle mass distribution results from coagulation in the heavily polluted concentrations experienced during the current study. The analysis suggests that carbon particles and sulfate/ammonium/nitrate particles exist separately in the atmosphere of the San Joaquin Valley until coagulation mixes them in the accumulation mode.     

LiCa3MgV3O12:Sm3+: A new high-efficiency white-emitting phosphor

A novel single-phased white-light-emitting phosphor Sm³⁺ doped LiCa₃MgV₃O₁₂ (LCMV) was developed. The LCMV host was one self-activated bluish-green emitting phosphor, which possessed an efficient excitation band in the 250–400?nm wavelength range and showed an intense broadband bluish-green emission with internal quantum efficiency (IQE) of 39%. Doping Sm³⁺ ions in to LCMV host induced tunable-color emissions, due to the energy transfer from [VO₄]^3? to Sm³⁺ ions. Importantly, under 340?nm excitation, the LCMV:Sm³⁺ can emitted bright white light by combining the self-activated luminescence of LCMV host and the red emissions of Sm³⁺ ions, and the IQE of the white-emitting composition-optimized LCMV:0.01Sm³⁺ phosphors reached up to 45%. These white-emitting LCMV:Sm³⁺ phosphors have potential applications in white light-emitting diodes and optical display devices.     

Investigating particle emissions and aerosol dynamics from a consumer fused deposition modeling 3D printer with a lognormal moment aerosol model

ABSTRACT

Particle emissions from consumer-fused deposition modeling 3D printers have been reported previously; however, the complex processes leading to observed aerosols have not been investigated. We measured particle concentrations and size distributions between 7 nm and 25 μm emitted from a 3D printer under different conditions in an emission test chamber. The experimental data was combined with a moment lognormal aerosol dynamic model to better understand particle formation and subsequent evolution mechanisms. The model was based on particles being formed from nucleation of unknown semivolatile compounds emitted from the heated filament during printing, which evolve due to condensation of emitted vapors and coagulation, all within a small volume near the printer extruder nozzle. The model captured observed steady state particle number size distribution parameters (total number, geometric mean diameter and geometric standard deviation) with errors nominally within 20%. Model solutions provided a range of vapor generation rates, saturation vapor pressures and vapor condensation factors consistent with measured steady state particle concentrations and size distributions. Vapor generation rate was a crucial factor that was linked to printer extruder temperature and largely accounted for differences between filament material and brands. For the unknown condensing vapor species, saturation vapor pressures were in the range of 10^?3 to 10^?1 Pa. The model suggests particles could be removed by design of collection surfaces near the extruder tip.

Copyright © 2018 American Association for Aerosol Research     

Control of Oxidation State of Eu Ions in Na2O–Al2O3–SiO2 Glasses

Glasses doped with well‐controlled Eu³⁺ and Eu²⁺ ions have attracted considerable interest due to the possibility of tuning the wavelength range of the emitted light from violet to red by using their ⁵D₀→⁷F_j and 5d–4f electron transitions. Glasses were prepared to dope Eu³⁺ ions in a Na₂O–Al₂O₃–SiO₂ system, and the changes in the valence state of Eu³⁺ ions and the glass structure surrounding the Eu atoms during heating under H₂ atmosphere were investigated using fluorescence spectroscopy, X‐ray absorption fine‐structure spectroscopy, and ²⁷Al magic‐angle spinning solid‐state nuclear magnetic resonance spectroscopy. The reduction behavior of Eu³⁺ ions was dependent on the Al/Na molar ratio of the glass. For Al/Na < 1, the Al³⁺ ions formed the AlO₄ network structure accompanied by the Na⁺ ions as charge compensators; the Eu³⁺ ions occupied the interstitial positions in the SiO₄ network structure and were not reduced even under heating in H₂ gas. On the other hand, in the glasses containing Al₂O₃ with the Al/Na ratio exceeding unity, the Eu³⁺ ions commenced to be coordinated by the AlO₄ units in addition to the SiO₄ network structure. When heated in H₂ gas, H₂ gas molecules reacted with the AlO₄ units surrounding Eu³⁺ ions to form AlO₆ units terminated with OH bonds, and reduced Eu³⁺ ions to Eu²⁺ via the extracted electrons.     

Topokinetics of the Polyene Formation in Poly(Vinyl Chloride) Films during Treatment with Nonoxidative Plasma

Abstract

Changes of the physical and chemical structure of a polymer solid during plasma treatment are mainly caused by two processes: the collision of ions, electrons and other particles with the polymer surface and the ultraviolet irradiation emitted by the plasma gas and absorbed by the polymer. The former process is limited to a very thin surface layer (only a few nanometers thick,¹ whereas the latter usually leads to a significant depth profile (up to 10 μm^1,2 or even more),³ depending on the kind of the plasma and the polymer investigated.     

Removal and recovery of heavy metal ions in fixed and semi-fluidized beds

Uptakes of heavy metal ions such as Pb²⁺ and Ni²⁺ were studied experimentally in fixed and semifluidized beds packed with a strong cation exchange resin, Amberlite 200. Single and binary aqueous solutions of lead and nickel ions were passed through ion exchange columns, and the exit concentrations were measured to get the breakthrough behavior of the ions. From the exit concentration profiles, the breakthrough time and the ion exchange capacity were evaluated. After removal of heavy metal ions from binary solution of lead and nickel ions until the breakthrough time, two metal ions were recovered by precipitation and resolubilization of lead. In this paper, the recovery yield and separation efficiency are rigorously discussed.     

Effect of MgO doping on the structure and optical properties of YAG transparent ceramics

The paper studies the features of Mg²⁺ ions as sintering aid for reactive solid-state sintering of YAG transparent ceramics. Phase composition, microstructure and optical properties of YAG ceramics, doped by 0 ÷ 0.15 wt.% MgO, were investigated. Solubility limit of Mg²⁺ ions in YAG crystal lattice was found to be in the range of 0.06 ÷ 0.1 wt.% of MgO additive. Substitution mechanism of Mg²⁺ in ceramic YAG was identified by comparison of XRD data and ab initio calculation. It was shown that within the solubility limit Mg²⁺ ions most likely substitute Al³⁺ sites. Doping by MgO above solubility limit led to precipitation of spinel secondary phases. It was found that doping by Mg²⁺ ions increases concentration of oxygen vacancies in YAG lattice that effectively promote sintering. The optimal concentration range of MgO sintering aid that allow to achieve YAG transparent ceramics was defined as 0.03 ÷ 0.06 wt.%.     

ToF‐SIMS investigation of epoxy resin curing reaction at different resin to hardener ratios

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal components analysis (PCA) were used to analyze diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) epoxy resin blend cured with isophorone diamine (IPD) hardener at different resin to hardener ratios. The aim was to establish correlations between the hardener concentration and the nature and progress of the crosslinking reaction. Insights into the cured resin structure revealed using ToF‐SIMS are discussed. Three sets of significant secondary ions have been identified by PCA. Secondary ions such as C₁₄H₇O⁺, CHO⁺, CH₃O⁺, and C₂₁H₂₄O₄⁺ showed variance related to the completion of the curing reaction. Relative intensities of C_xH_yN_z⁺ ions in the cured resin samples are indicative of the un‐reacted and partially reacted hardener molecules, and are found to be proportional to the resin to hardener mixing ratio. The relative ion intensities of the aliphatic hydrocarbon ions are shown to relate to the cured resin crosslinking density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and Spectroscopy of Nd3+-Doped Tellurite-Based Glasses

This study presents a spectroscopic investigation of tellurite glasses which contain Nd³⁺ ions. The investigation was directed to the characterization of the glasses and to the study of the spectral emission from Nd³⁺ ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured. As for Nd³⁺, the absorption, emission, and response to pulsed excitation measurements were performed and the results are reported. The absorption spectra of the samples were analyzed using the Judd–Ofelt approach.     

Carbon monoxide hydrogenation over silica-supported ruthenium-copper bimetallic catalysts

The catalytic properties of a series of ruthenium-copper catalysts supported on silica were studied. It was found that while the amount of CO adsorbed at 273 K measured with the pulse-flow method is higher on the catalysts with a small concentration of copper than on the pure ruthenium catalyst, the yield of Ru⁺ secondary ions on fast atom bombardment of the catalyst surface with argon is suppressed by the addition of copper. The activity for CO disproportionate as well as CO hydrogenation were drastically reduced by the presence of copper. It is estimated that an ensemble of between 4 to 6 adjacent ruthenium atoms is required for CO disproportionation and one of between 9 to 13 adjacent ruthenium atoms is required for CO hydrogenation. Comparisons between the properties of the supported catalysts and those of single-crystal model catalysts were made.     

Enhancing upconversion emission and temperature sensing modulation of the La2(MoO4)3: Er3+, Yb3+ phosphor by adding alkali metal ions

Trivalent Er³⁺-doped La₂(MoO₄)₃ upconversion phosphors with intense green emmision were synthesized at 800 °C by the solid-state reaction route, promoting the development of novel optical thermometry. The color emitted from the samples was minorly affected by the excitation power and doping concentration. Yb³⁺ is a better sensitizer for the La₂(MoO₄)₃: Er³⁺ phosphor and it can enhance the emission intensity when a certain amount is co-doping in the system. The up-conversion luminescent mechanism was investigated using the pump power-dependent UC emission spectra. Alkali metal doping increased the up-conversion emission intensities drastically, and Li⁺ ions can enhance the luminous intensity by more than 20 times. The fluorescence intensity ratio of the transition emission ²H_11/2-⁴I_15/2 and ⁴S_3/2-⁴I_15/2 was used to study upconversion optical temperature sensing. The sensitivity changes from doping with diverse alkali metal ions and their effects on the optimal temperature range are discussed in detail. Alkali metal ions doping extended the temperature range, indicating that this phosphor is a potential candidate for temperature-sensing probes.     

Er3+/Tm3+ Co‐diffusion Characteristics in LiNbO3 Crystal

Co‐diffusion characteristics of Er³⁺ and Tm³⁺ ions in LiNbO₃ crystal have been studied, together with two other properties: doping effect on refractive index of substrate, and Li out‐diffusion. Er³⁺/Tm³⁺‐codoped LiNbO₃ single‐crystals were prepared by co‐diffusion of stacked Er‐ and Tm‐metal thin films, coated onto parts of the surfaces of X‐ and Z‐cut congruent LiNbO₃ crystal plates, at different temperatures and different durations in air. After diffusion, the surface refractive indices of the doped and undoped parts were measured by prism coupling technique, and the surface composition was evaluated from the measured indices. The results show that the dopings have negligible effect on the substrate index and the Li out‐diffusion depends mainly on the diffusion temperature. The Er³⁺ and Tm³⁺ profiles were studied using secondary ion mass spectrometry, and a co‐diffusion dynamical model is proposed and verified experimentally. From the measured profiles, the temperature‐dependent Er³⁺/Tm³⁺ diffusivity and solubility were obtained together with other relevant parameters, such as diffusion constant, activation energy, solubility constant and heat of solution. The Er³⁺ and Tm³⁺ co‐diffusion exhibits similar temperature dependent diffusivity, and the dependence is similar to that of single‐diffusion. In the co‐diffusion case, the total solubility consists of two parts: Er³⁺ and Tm³⁺ parts, there is no anisotropy, and the value is equal to that of single‐diffusion case, in which both ions have the similar solubility. The Er³⁺ and Tm³⁺ parts of solubility change relatively with the initial metal film thicknesses and hence have different temperature dependences. Nevertheless, their sum, i.e., the co‐diffusion solubility, remains a constant at a given temperature.     

Galvanic interaction of pyrite with Cu activated sphalerite and its effect on xanthate adsorption

In the presence of Cu ions, a packed bed electrochemical reactor (PBER) was employed to deliberately avoid or induce galvanic coupling between pyrite and Cu‐activated sphalerite. The effect of galvanic interaction on Cu ions uptake and xanthate adsorption were investigated. Solution chemistry and surface chemistry studies (ethylenediaminetetraacetic acid extraction and time of flight secondary ion mass spectrometry) have observed that when sphalerite and pyrite were galvanically coupled, Cu ions migrated from the pyrite surface to the surface of the sphalerite. Along with the marked decrease in the adsorption of Cu ions on pyrite, xanthate adsorption on the minerals also dramatically dropped. The pseudo‐adsorption rate constant for the minerals in the mixed mode is only 0.0583 s^?1, much less than that in the decoupled mode, which is 0.1368 s ^?1. This testing program shows that the galvanic coupling of minerals contributes to more copper transfer and Cu ions preferentially adsorbed by sphalerite rather than pyrite. This affects the pyrite surface and causes it to become xanthate unflavoured.     

Photoluminescence properties of praseodymium doped cerium oxide nanocrystals

The structure and photoluminescence (PL) properties of CeO₂ nanocrystals synthesized by the microwave-assisted hydrothermal (MAH) method with different praseodymium (Pr³⁺) ions contents were performed. X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance ultraviolet-visible (UV-vis), Fourier transform Raman (FT-Raman) spectroscopies and PL measurements at room temperature were employed. XRD patterns indicated that the nanocrystals are free of secondary phases and crystallize in the cubic structure while FT-Raman revealed a typical scattering mode of fluorite type. The UV-vis spectra suggested the presence of intermediate energy levels in the band gap of these nanocrystals. The most intense PL emission was obtained for CeO₂ nanocrystals doped with 1.6% of Pr³⁺ ions and smaller particle size.