Changes In Elemental Composition Research Articles

Ontogeny and Early Steps of the Calcification Process in Coralline Algae Lithophyllum corallinae (Florideophyceae, Rhodophyta)

Coralline algae (Rhodophyta, Florideophyceae) are one of the most abundant organisms in the hard-bottom marine photic zone where they provide settlement substrates, structure and shelter on rocky substrates. Coralline algae also play important roles in tropical reefs, both cementing corals together and producing substantial amounts of calcium carbonate. The ecological roles of coralline algae in the marine environment are related to the biomineralization process that occurs in the cell walls. Currently, this group of algae is receiving renewed attention from researchers from different fields, especially due to possible effects of climate changes over its magnesium calcite skeleton. Despite this renewed attention, we still have poor information regarding the first steps of coralline algae ontogeny and calcification. The aim of this study was to describe the earlier steps ofLithophyllum corallinaedevelopment and its calcification process. Algae were collected at Vermelha Beach, Rio de Janeiro city. Adult crusts released spores that settled over microscope slides. The germinating spores were analyzed by Polarizing Light Microscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Transmission Electron Microscopy and Atomic Force Microscopy. Results showed that cell walls mineralization begins at third spore cell division (8 cells specimen), evidenced by changes in light polarization, elemental composition and hardness, restricted to the cell walls of the innermost part of the developing spore. Nanopores in calcite crystals structure were identified, evidencing macromolecules occlusion, a feature especially important to prevent calcite skeleton cracking in high-energy environments. The beginning of this process could be related to spore size, availability of organic matrix and energy from photosynthesis. All the analysis also confirmed the lack of calcification in the cell walls of the outermost part of the germinating spore, which allows the growth of the individual; but mainly indicates a high level of control in coralline algae mineralization process, representing a relevant information in future studies on coralline algae calcification, including those testing climate changes scenarios.

Structural and chemical changes in pyrogenic organic matter aged in a boreal forest soil

Pyrogenic organic matter (PyOM) is formed during wildfires and prescribed burnings or produced intentionally in the form of biochar for soil amendment purposes. It is attracting a growing scientific and practical interest due to its important role in the global carbon cycle and agronomic applications as a soil enhancer. Most of the studies on the physicochemical properties of PyOM have been conducted using fresh biochars even though the characteristics of PyOM are expected to alter due to aging processes in soil environment. In this paper, we report the results of a study that utilized X-ray microtomography and elemental analysis to investigate the chemical and structural changes in the PyOM formed during prescribed burning events and aged thereafter for 1–71 years in a boreal forest soil. Our results indicate that changes in elemental composition occurred at decadal timescales, and an apparent steady state was reached ca. 30 years after PyOM formation and exposure to the environment. At such timescales, PyOM was able to retain its porous structure originating from the cellular structure of the initial wood tissues. However, structural analysis revealed several effects of aging on the pore structure, such as the formation of surface coating layers, pore fillings, and fractures. These changes may alter pore size distribution and accessibility of the pores and further alter the influence of PyOM on soil functions, such as the transfer and retention of water and nutrients in PyOM pores.

Removal of arsenic (V) using natural zeolite: Fixed bed column tests

Water pollution with arsenic has received special attention due to its health implications for the population. Therefore, its removal from groundwater is of vital importance. The main objective of this work was to investigate the removal performance of dissolved arsenic in multi-ionic solutions using a low-cost mineral material and, in parallel, to be able to compare its sorption capacity from its nature as a chemically modified form. To do this, fixed bed columns packed with natural zeolites (ZN) and chemically modified (ZMQ) with 1 M H2SO4 were implemented. Sorption studies showed that chemical conditioning improved the maximum sorption capacity (qe), the breakthrough time, the exhaustion time and the effluent volume with a concentration equal to or less than 10 μg/L, correspondingly by 150, 45, 88 and 281 %, concerning the ZN. The breakthrough curves for the removal of As (V) were fitted with various mathematical models, being the Thomas nonlinear model the one that best reproduced the kinetics of sorption under the implemented operating conditions. The X-ray diffraction concluded that there is no structural change in the zeolite after the chemical modification, therefore, the increase in the sorption capacity of the ZMQ was attributed to the morphological and elemental chemical composition changes on their surface. These results show that the ZMQ can be used as a viable alternative, from the point of view of purifying efficiency, concerning its non-acidified form, for the removal of As (V).

Microstructures, Mechanical Behavior, and Radiation Damage of (TiVCr)x-(TaW)1-x Binary System High-Entropy Alloy Films

An experimental method for preparing high-entropy thin films with gradient changes of alloying elements by magnetron sputtering co-deposition is proposed in this work to evaluate the effect of alloying element composition changes on the properties of non-equal molar ratio high-entropy alloys. The (TiVCr)x-(TaW)1-x binary system thin films were deposited by a magnetron sputtering system with two intermediate alloy targets. The surface morphology, element composition, roughness, and phase structure of the coatings were studied with scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffractometer (XRD), atomic force microscope (AFM), and transmission electron microscope (TEM). The results show that at x = 0.51, the films had the best mechanical properties under the action of multiple strengthening mechanisms, and the hardness and modulus reached 27.61 GPa and 274.42 GPa, respectively. Due to higher hardness and special surface morphology, the films showed a lower average friction coefficient and had excellent wear resistance with wear rates of 0.34 and 5.01 × 10−9 mm3/(N·mm), respectively. On the other hand, it was found that forming a BCC polycrystalline structure and an amorphous-mixed structure can improve the radiation resistance of the material.

Multi-Elemental Analysis of Human Optic Chiasm—A New Perspective to Reveal the Pathomechanism of Nerve Fibers’ Degeneration

The effect of metals on the functioning of the human eye is multifactorial and includes enzyme activity modulation, trace metal metabolic pathways changes, and cytotoxic activity. Functional dysfunctions appear mostly as a result of the accumulation of toxic xenobiotic metals or disturbances of micronutrients’ homeostasis. So far, the affinity of selected metals to eye tissues, i.e., the cornea, choroid, lens, and anterior chamber fluid, has been most studied. However, it is known that many eye symptoms are related to damage to the optic nerve. In order to fill this gap, the aim of the study is to perform a multi-element analysis of tissue collected postmortem from optic chiasm and optic nerves. A total of 178 samples from 107 subjects were tested. The concentrations of 51 elements were quantified by inductively coupled plasma mass spectrometry (ICP-MS) after the wet-mineralization step. In terms of elemental composition, the optic chiasm is dominated by two trace elements, i.e., iron (Fe) and zinc (Zn), besides macro-elements Ca, K, Na, P, and Mg. The subjects formed a homogeneous cluster (over 70% subjects) with the highest accumulation of aluminum (Al). The remaining two departing clusters were characterized by an increased content of most of the elements, including toxic elements such as bismuth (Bi), uranium (U), lead (Pb), chromium (Cr), and cadmium (Cd). Changes in elemental composition with age were analyzed statistically for the selected groups, i.e., females, males, and subjects with alcohol use disorder (AUD) and without AUD. A tendency of women to lose Se, Cu, Zn, Fe with age was observed, and a disturbed Ca/Mg, Na/K ratio in subjects with AUD. Although the observed trends were not statistically significant, they shed new light on the risks and possible pathologies associated with metal neurotoxicity in the visual tract.

Mineralogy and bulk geochemistry of a fumarole at Hverir, Iceland: Analog for acid-sulfate leaching on Mars

AbstractIceland’s Námafjall geothermal area exhibits a range of alteration environments. Geochemical and mineralogical analyses of fumaroles and hot springs interacting with Holocene basaltic lavas at Hverir, and with Pleistocene hyaloclastites atop nearby Námaskar∂, reveal different patterns of alteration depending on the water/rock ratio, degree of oxidation, and substrate composition and age. The focus of this study is a transect of a Hverir fumarole that has formed a bullseye pattern of alteration of a Holocene basaltic lava flow. Surface samples and samples collected from shallow pits were analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) to constrain changes in mineral assemblage and major elemental composition with both distance and depth. Elemental sulfur is concentrated near the vent, with leached deposits with amorphous silica and anatase nearby and kaolinite, hematite, and jarosite/alunite-group sulfate minerals farther out, with smectites and less altered material at the margins, though smaller-scale mineralogical diversity complicates this pattern.Silica phases include amorphous silica (most samples), cristobalite (some samples in the leached part of the apron), and quartz (minor constituent of a few samples). The silica was concentrated through residual enrichment caused by leaching and is accompanied by a significant enrichment in TiO2 (in anatase). The presence of abundant cristobalite in a surface fumarole-altered Holocene basaltic lava flow most likely reflects cristobalite formed during the devitrification of volcanic glass or precipitation from fumarolic vapors, rather than high-temperature processes. Minor, localized quartz likely reflects diagenetic maturation of earlier-formed amorphous silica, under surface hydrothermal conditions. Natroalunite, natrojarosite, and jarosite are all present and even exhibit compositional zonation within individual crystals, showing that under surface hydrothermal conditions, these minerals can form a significant solid solution.The high iron content of the substrate basalt and the prevalence of Fe-sulfates and Fe-oxide spherules among the alteration products makes this geothermal area an especially useful analog for potential martian hydrothermal environments. The residual enrichment of silica in the leached deposits of the Hverir fumarole apron could serve as an acid-sulfate leaching model in which amorphous silica forms without appreciable sulfur-bearing phases in many samples, a possible analog for silica-rich soils in the Columbia Hills on Mars. The coexistence of hematite spherules and jarosite-group minerals serves as an intriguing analog for a volcanic/hydrothermal model for hematite and jarosite occurrences at Meridiani Planum.

Combined electron-ion-plasma treatment of 40Cr steel surface

Complex alloying, combining in a certain sequence the saturation of surface layer of material with atoms of metals and gases, is now widely used in most industrialized countries of the world. The present work is devoted to the revelation and analysis of dependences of element and phase composition, defect substructure, mechanical (microhardness) and tribological (wear resistance and friction coefficient) properties changes of alloying carbon steel subjected to combined treatment including the saturation of the sample surface layer by aluminum and subsequent nitriding. The material used for the study was AISI 5135 steel, which in the initial state has a structure represented by ferrite grains and pearlite grains of lamellar morphology. The combined modification was carried out in a single vacuum space on the TRIO setup with the chamber dimensions of 600×600×600 mm3 equipped by switching unit for realization of elion (electron and ion) mode of treatment. Aluminizing was carried out at the temperature of 963 К during 4 h. The cathode of electroarc evaporator was made of A7 grade aluminum alloy (98.8 % Al). Subsequent nitriding of aluminized layer was carried out at the temperature of 803 К during 2 h. It was established that the modified layer with the thickness of 70 μm is formed as a result of the combined treatment. It is demonstrated that the combined steel modification is accompanied by the formation of multiphase submicro- and nanostructure state including aluminum nitrides, iron and chromium nitrides and aluminides. It is revealed that the steel hardness is maximal on the modification surface and it exceeds by 3 times that of the initial steel. Wear resistance under the dry conditions decreases after the combined modification.

Effect of the Plasma Gas Type on the Surface Characteristics of 3Y-TZP Ceramic.

Plasma surface treatment can be an attractive strategy for modifying the chemically inert nature of zirconia to improve its clinical performance. This study aimed to clarify the effect of plasma gas compositions on the physicochemical surface modifications of 3 mol% yttria-stabilized zirconia (3Y-TZP). The cold, atmospheric plasma discharges were carried out by using four different plasma gases, which are He/O2, N2/Ar, N2, and Ar from an application distance of 10 mm for 60 s. Static contact angles were measured to define the surface free energy. Changes in elemental composition, surface crystallinity, and surface topography were assessed with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM), respectively. A significant decrease in water contact angle was observed in all plasma groups with the lowest value of 69° in the N2/Ar group. CLSM and SEM investigations exhibited no morphological changes in all plasma groups. XPS revealed that a reduction in the surface C content along with an increase in O content was pronounced in the case of N2/Ar compared to others, which was responsible for high hydrophilicity of the surface. XRD showed that the changes in crystallite size and microstrain due to oxygen atom displacements were observed in the N2/Ar group. The N2/Ar plasma treatment may contribute to enhancing the bioactivity as well as the bonding performance of 3Y-TZP by controlling the plasma-generated nitrogen functionalities.

Investigation of a Mechanism of Structural Transformations in High-Strength Steel

Mechanical, technological and operational properties of metal materials are largely influenced by changes of concentrations, morphology, dimensions, localization, elemental and phase composition of dispersed precipitates. This paper is devoted to a study of dispersed carbides of submicron size at tempering of high-strength medium-carbon steel. The main emphasis is on comparing the data obtained by small-angle neutron scattering and transmission electron microscopy. As a result of the analysis, it was found that carbide growth begins in the investigated steel immediately after quenching when the tempering temperature increases. First, it is fixed by a transmission electron microscopy and a small-angle neutron scattering and then above ~ 300 ° C carbide growth is fixed by neutron diffraction. The residual austenite is also completely dissolved by the time the temperature reaches ~ 300 °C. A good matching has been reached for the methods used. It has been shown that a complex use of integral and local methods allows to obtain fully information about the structure and properties of the investigated material.

Ti/TiO2/NiWO4 + WO3 composites for oxidative desulfurization and denitrogenation

The catalytic properties of Ti/TiO2/NiWO4 + WO3 composites fabricated by plasma electrolytic oxidation (PEO) of titanium in a solution containing 0.1 mol/L Na2WO4 + 0.1 mol/L CH3COOH + 0.05 mol/L Ni(CH3COO)2 were studied in model reactions of peroxide oxidation of thiophene (T), dibenzothiophene (DBT), methylphenyl sulfide (MPhS), and pyridine (Py). This paper demonstrates for the first time that such composites are promising for catalytic oxidation of both S-containing and N-containing petroleum compounds. By the example of the reaction of dibenzothiophene oxidation, the optimal reaction temperature (60 °C) and the content of hydrogen peroxide in the reaction mixture were established, and the efficiencies of the Ti/TiO2/NiWO4 + WO3 and Ti/TiO2/WO3 composites were compared to show the role of nickel in increasing their activity and stability. It was found that, with respect to organosulfur substrates, the activity of the Ti/TiO2/NiWO4 + WO3 catalyst decreases in the series: methylphenyl sulfide > dibenzothiophene > thiophene. The changes in surface morphology and elemental composition of composites after catalytic tests have been evaluated using SEM, EDS and XPS. It has been established that the use of the Ti/TiO2/NiWO4 + WO3 catalyst makes it possible to achieve a deep degree of desulfurization of the diesel fraction of petroleum feedstock (>90%).

Experimental study on viscosity reduction of heavy oil with water content by synergistic effect of microwave and nano-catalyst

With the depleting of conventional oil and gas resources, viscosity reduction of heavy oil became more and more important as a research focus. As a new method of viscosity reduction, the mechanism of microwave-assisted with nano-catalysts is still unclear. In this paper, the viscosity reduction of nano-catalyst and microwave treatment of heavy oil in different water content was studied. The experimental results showed that the maximum viscosity reduction was 96.81 % when the water content was 50 wt% under the conditions of microwave heating power of 614w, microwave heating temperature of 68 °C and nickel nano-catalyst concentration of 0.8 wt%. The oil samples before and after three treatments were analyzed by infrared spectroscopy, element analysis, four-component separation, and two-dimensional gas chromatography-mass spectrometry. By analyzing the changes of functional group, element composition, and component content, the effects of microwave and nano-catalyst were studied. The results showed that the resin and asphaltene content decreased by 17.3 wt%, and the hydrogen to carbon ratio was 2.14 when the water content was 30 wt% under the conditions of microwave heating power of 666w, microwave heating temperature of 65 °C and nickel nano-catalyst concentration of 2.3 wt%, which proved that microwave treatment assisted with nano-catalysts could increase the cracking capacity of macromolecules and the production of coke.

Physical properties and acid resistance of geopolymer mortar prepared from synthetic water containing hydrochloric acid

This article describes an experimental research to evaluate the physical characteristics and performanceof geopolymer mortar synthesized with synthetic water containing strong acidic substance after 28, 56, and 84 days of curing in the laboratory. Two distinct geopolymer mortar mixes were created based on previous investigations: controlled geopolymer mortar (CGM) and test geopolymer mortar (TGM). The control geopolymer mortar utilized demineralized water to produce the alkaline reactant solution that activated the fly ash, while the test geopolymer mortar employed synthetic water containing 100 mg/L hydrochloric acid. Characterization tests were carried out after the 28-day assessment of physical characteristics to determine the changes in morphology and elemental composition. A change in morphology and elemental composition was discovered through characterization. Following characterization testing, acid resistance tests on CGM and TGM specimens were conducted by immersing in 2 percent hydrochloric and sulphuric acid solutions, respectively. According to the findings, the TGM combination showed better physical characteristicsand demonstrated increased resistance to acid attacks.

Fluid‐driven transformation of blueschist to vein eclogite during the Early Eocene in a subducted sliver of continental crust (Monte Emilius, Italian Western Alps)

AbstractIn the Penninic nappe stack of the Western Alps, high‐ to ultrahigh‐pressure metamorphic ophiolites of the Zermatt‐Saas Zone are associated with slivers of continental crust. In one of these slivers, Monte Emilius, the overprinting of pre‐Alpine granulite‐facies rocks by subduction‐related, Alpine eclogite‐facies metamorphism can be studied. Mafic granulites were initially transformed into blueschists. In a second step, shear zones were developed in which the blueschists recrystallized to fine‐grained, foliated glaucophane eclogites, and eclogite veins. The combination of petrographic and field observations as well as whole‐rock compositions suggests that the eclogite assemblage formed only in shear zones where Ca‐metasomatism induced a change in major element composition. These substantial differences in bulk rock composition demonstrate how spatially limited eclogitization may be controlled by chemical redistribution, the degree of fabric development, and associated metamorphic reactions along fluid pathways. Thermodynamic modelling of selected bulk rock compositions yielded only slightly different conditions of 1.8 ± 0.1 GPa/550 ± 50°C for blueschist and 1.9–2.3 GPa/550 ± 50°C for eclogite, constraining Ca‐rich fluid infiltration and transformation to a depth of ~60–70 km. Eclogitization occurred in the Early Eocene at 52.96 ± 0.91 Ma, as indicated by a well‐defined Lu–Hf garnet isochron.

Temporal Archive of Atmospheric Microplastic Deposition Presented in Ombrotrophic Peat

Ombrotrophic peatland—fed solely from atmospheric deposition of nutrients and precipitation—provide unique archives of atmospheric pollution and have been used to illustrate trends and changes in atmospheric trace element composition from the recent decadal to the Holocene period. With the acknowledgment of atmosphere plastic pollution, analysis of ombrotrophic peat presents an opportunity to characterize the historical atmospheric microplastic pollution prevalence. Ombrotrophic peatland is often located in comparatively pristine mountainous and boreal areas, acting as sentinels of environmental change. In this paired site study, a Sphagnum ombrotrophic peat record is used for the first time to identify the trend of atmospheric microplastic pollution. This high altitude, remote location ombrotrophic peat archive pilot study identifies microplastic presence in the atmospheric pollution record, increasing from <5(±1) particles/m2/day in the 1960s to 178(±72) particles/m2/day in 2015–2020 in a trend similar to the European plastic production and waste management. Compared to this catchment’s lake sediment archive, the ombrotrophic peat core appears to be effective in collecting and representing atmospheric microplastic deposition in this remote catchment, collecting microplastic particles that are predominantly ≤20 μm. This study suggests that peat records may be a useful tool in assessing the past quantities and trends of atmospheric microplastic.

Investigation of spectroscopic and photoluminescence properties of Erbium doped phosphate (P2O5-K2O3-Al2O3) glasses

Erbium (Er) doped P2O5-K2O3-Al2O3:Er2O3 glasses (KPEr) with different contents of Er3+ ions were fabricated by famous melt-quenching technique. The fabricated samples were characterized by using physical, X-ray photoelectron spectroscopy (XPS), photoluminescence, absorption, and J-O analysis techniques. The XRF analyses were performed in order to know the change in elemental composition of fabricated glasses, while using the various concentrations of Er3+ ions. Three emission peaks were observed, two peaks in visible regions of 526 nm (2H11/2→4I15/2) and 550 nm (4S3/2→4I15/2) and one peak in near infrared (NIR) region of 1545 nm (4I13/2→4I15/2). Nine peaks were observed in absorption spectra in the range of 390–1800 nm. The trend of JO parameters for the present KPEr6 glass sample is Ω2> Ω4> Ω6. Higher values of stimulated emission cross-section σemi(λ), full wave half maxima FWHM and (FWHM x σemi (λ)), for KPEr6 indicate that the present glass has potential candidate to be used for broadband amplification in telecommunication. The McCumber theory is used to study absorption and emission cross-section for 4I13/2→4I15/2 transition. The luminescence colors of these samples were almost entirely fall in the yellow-green (Y-G) region (x = 0.33, y = 0.64) in the CIE 1931 diagram. The calculated CCT values for our prepared glasses were found to be 5554 K. The present study suggest that KPEr glass samples have potential candidate for broadband amplification in telecommunication, green LED and display devices.

ЗАКОНОМЕРНОСТИ ФОРМИРОВАНИЯ МИКРОЭЛЕМЕНТНОГО СОСТАВА ПОЧВ ПОД ГОРНО-ЛУГОВОЙ РАСТИТЕЛЬНОСТЬЮ БОЛЬШОГО КАВКАЗА

Report. The purpose of the work is to identify the features of the formation of the microelement composition of soils under the mountain meadow vegetation of the Greater Caucasus based on the analysis of literary materials and the results of our own field research. Methods. The study of the microelement composition of soils under subalpine and alpine vegetation was carried out on the territory of the Teberdinsky State Biosphere Reserve. Traditional methods of soil-geochemical studies were used with the laying of soil sections, the selection of soil samples and their analysis for the content of four trace elements (Zn, Cu, Pb and Cd). Determination of trace elements was carried out by voltammetric and atomic absorption methods. The humus content was determined by the Tyurin method with wet salting, the pH of the water extract was determined potentiometrically. Statistical processing of the obtained data was performed in the Statistica 10 program. The microelement composition of soil-forming rocks was compared with the clarks of chemical elements in the upper part of the continental crust; the microelement composition of mountain-meadow soils was compared with the clarks of the soils of the world. The radial distribution of trace elements in the soil profile was analyzed. The qualitative trace element composition of soils was characterized as a sequence of decreasing the content of trace elements in the humus horizon. Results. It is established that the microelement composition of soils under the mountain-meadow vegetation of the Western Caucasus is formed under specific conditions that affect the course of soil processes. High solar insolation, low temperatures, intensive humidification throughout the year affects the features of the processes of humification, the formation of clay minerals in the soil and other products of intra-soil weathering. The predominance of acid hydrolysis processes leads to the predominant accumulation of aluminosilicates, Fe hydroxides, chelated organomineral complexes in the soil profile, which play a leading role in the binding of trace elements. The microelement composition of mountain-meadow soils under subalpine vegetation is formed with more intensive processes of humus formation and oglinivaniya. These soils are characterized by a more pronounced biogenic accumulation of Cu and Zn in the humus horizon, the illuvial nature of the Cd distribution is more pronounced. The microelement composicomposition of mountain-meadow soils under alpine and rock-scree vegetation is formed against the background of relatively weakened processes of humus formation, humus accumulation and oglinivaniya. This affects the lower intensity of biogenic accumulation of trace elements, their leaching into the lower part of the profile. Conclusions. The main regularities of the formation of the microelement composition of mountain-meadow soils are determined by the special conditions in which these soils develop. The fixation of trace elements in mountain-meadow soils occurs mainly on aluminosilicates, Fe, Mn hydroxides and chelated organomineral complexes, which largely form the silty fraction. The movement of silty particles along the soil profile leads to the redistribution of trace elements associated with them. The granulometric composition, which is an indicator of the content of the silty fraction and its distribution along the soil profile, is of great importance when characterizing the microelement composition of mountain meadow soils. The established regularities of the formation of the microelement composition of mountain-meadow soils allow us to determine the main directions of economic activity that will contribute to the preservation of their ecological state. This is, first of all, the rational use of pasture resources of mountain meadows with the introduction of a system of alternating mowing, changing the main pastures with spare ones during the year for their restoration. An important component should be monitoring changes in the trace element composition of mountain meadow soils, which will allow timely response to changes and make adjustments to the structure of the use of these soils.

Temporal evolution of metallic element composition and environmental impact in consumer electronic devices: A study of smartphones

Smartphones enable the function and evoluation of modern society. However, with a compressed product life cycle and growing consumer demand, a significant number of smartphones reach End-of-Life (EoL) annually. At the same time, due to many unique physical properties, rare earth elements (REE), critical, platinum group metals (PGMs) and other important metals are key for the manufacturing of smartphones. Hence, from various economic, sustainable resource management and environmental perspectives, it is crucial to understand how the metal content of different smartphones generations change over time. This study provides a detailed analysis of a high production smartphone series, produced between 2010 and 2015. Devices were first disassembled and their printed circuit boards assembly, back cameras and near field communication/wireless charging parts were analyzed for 60 elements, 30 of which are classified as environmentally critical. Results indicate that up to 70% of the three analyzed smartphone components by weight are important recyclable metals. The highest concentration elements, Cu, Ni, Sn, Zn and Fe, accounted for 93.3% while REEs and PGMs collectively accounted for 0.53% of the total recoverable elements by weight. The cradle-to-gate environmental impacts will vary proportionally based on temporal changes in elemental composition.

Responses of Marine Diatom-Dinoflagellate Competition to Multiple Environmental Drivers: Abundance, Elemental, and Biochemical Aspects.

Ocean-related global change has strongly affected the competition between key marine phytoplankton groups, such as diatoms and dinoflagellates, especially with the deleterious consequency of the increasing occurrence of harmful algal blooms. The dominance of diatoms generally shifts toward that of dinoflagellates in response to increasing temperature and reduced nutrient availability; however, contradictory findings have also been observed in certain sea areas. A key challenge in ecology and biogeochemistry is to quantitatively determine the effects of multiple environmental factors on the diatom-dinoflagellate community and the related changes in elemental and biochemical composition. Here, we test the interplay between temperature, nutrient concentrations and their ratios on marine diatom-dinoflagellate competition and chemical composition using bi-algal competition experiments. The ubiquitous diatom Phaeodactylum tricornutum and dinoflagellate Prorocentrum minimum were cultivated semi-continuously, provided with different N and P concentrations (three different levels) and ratios (10:1, 24:1, and 63:1 molar ratios) under three temperatures (12, 18, and 24°C). The responses of diatom-dinoflagellate competition were analyzed by a Lotka-Volterra model and quantified by generalized linear mixed models (GLMMs) and generalized additive models (GAMs). The changes in nutrient concentrations significantly affected diatom-dinoflagellate competition, causing a competitive superiority of the diatoms at high nutrient concentrations, independent of temperature and N:P supply ratios. Interestingly, the effect amplitude of nutrient concentrations varied with different temperatures, showing a switch back toward a competitive superiority of the dinoflagellates at the highest temperature and at very high nutrient concentrations. The ratios of particulate organic nitrogen to phosphorus showed significant negative correlations with increasing diatoms/dinoflagellates ratios, while lipid biomarkers (fatty acids and sterols) correlated positively with increasing diatoms/dinoflagellates ratios over the entire ranges of temperature, N and P concentrations and N:P ratios. Our results indicate that the integration of phytoplankton community structure and chemical composition provides an important step forward to quantitatively understand and predict how phytoplankton community changes affect ecosystem functions and biogeochemical cycles in the ocean.

Fabrication of copper‐niobium‐oxygen complexes as a photocathode for p‐type dye‐sensitized solar cell

Thin film of copper niobate ternary oxide with various compositions was fabricated by pulsed laser deposition technique. Formation of a single phase of monoclinic CuNbO3, monoclinic CuNb3O8 (Cu[I]), and triclinic Cu3Nb2O8 (Cu[II]) thin films was confirmed from the X-ray diffraction and selected area energy diffraction analysis. Field emission scanning electron microscopy and high-resolution tunneling electron microscope show CuNbO3 and CuNb3O8 system that exhibits polyhedron and triangular structure, respectively, while Cu3Nb2O8 system shows layered structure formation. The linear spectrum shows a minimal variation in bandgap concerning to the change in elemental composition and position of the copper and niobium atom. Cyclic voltammetry studies endorse that the prepared films are highly adhesive even after 100 cycles. With various compositions of copper niobate thin films as photocathode, N719 sensitized p-dye-sensitized solar cells (p-DSSCs) were fabricated for the first time. Monoclinic CuNbO3 system offers outstanding photovoltaic performance of 2.19% and thus can be used as an alternative for well-known NiO p-DSSC. Advantages of copper-niobium-oxygen systems open a new route of photocathodic materials for p-DSSC and tandem solar cells.

Immersion studies of Al2O3 – 13% TiO2 and Cr2O3 coatings on ship hull plate in simulated seawater environment in laboratory

In the present work the corrosion behaviour of Al2O3 – 13% TiO2 and Cr2O3 coatings in an artificial seawater environment is investigated by immersion test and weight measurement methods. The coatings are deposited on ship hull steel by D-Gun flame spray method. The microstructure and phase composition of coatings are studied by scanning electron microscopy (SEM) and electron dispersive spectrum (EDS). The corrosion resistance of coatings is compared on the basis of weight measurement and visualization technique. The change in microstructure and elemental phase composition is also observed by the corroded micrographs.