Decrease In Cu Research Articles

Foliar application of commercial humic substances for possible increase of nutrient status and yield of oilseed rape

Inconsistent results on the effects of humic substances (HS) on yield and nutrient status of important food crops, including oilseeds, confirm the need for further research on different HS products to match their use to actual field conditions. The aim of this study was to evaluate the effect of foliar application of commercially produced peat- and vermicompost-derived HS preparations on nutrient status and yield of spring oilseed rape (Brassica napus). The field experiment was carried out in Stende State Cereals Breeding Institute, Latvia, during the vegetation season of 2012, using the spring oilseed rape cultivar ‘Perfect’. Although foliar sprays of HS were applied during the critical stages of crop development from rapid growth to flowering, they were ineffective in improving the supply of the deficient nutrients (N, K, B, Zn, Cu) in leaves. Moreover, both tested HS products caused a decrease in Cu and B content in the seeds, which resulted in a negative trend in oilseed rape seed yield. Therefore, the conducted experiment demonstrated that foliar application of both HS preparations was ineffective to promote nutrient status and did not contribute to spring oilseed rape yield.

Sulfide resorption contributes to porphyry deposit formation in collisional settings

Production of Cu-rich melts via melting of sulfide-bearing lower crustal cumulates is thought to contribute to porphyry Cu formation in the post-collisional Gangdese belt (Tibet). We present new whole rock, including platinum group elements (PGE) data, for ore-causative granites (OCG), ore-related granites (ORG) and barren granites (BG) from the Gangdese belt. The OCG, ORG and BG show indistinguishable Cu, PGE and Cu/Ag behavior during differentiation down to ∼2 wt% MgO. These systematics, together with the occurrence of sulfides, demonstrate that the propensity for some Gangdese magmas to be ore-associated is unrelated to melting of sulfide-bearing cumulates or the relative timing of sulfide fractionation. The behavior of chalcophile and siderophile elements during differentiation of the OCG, ORG and BG diverges when melts evolve past 2–3 wt% MgO and exsolve H2O, S and Cl: the BG show a decrease in Cu, whereas the OCG and ORG show highly variable Cu, Au, and PGE trends. Because S degassing causes melts to become sulfur undersaturated and because Cu is highly soluble in Cl-rich fluids, any sulfides in contact with the melt or magmatic fluids following volatile exsolution would dissolve. Continual injection, cooling and ascent of magmas through the Gangdese crust is expected to have resulted in the development of regions of crystal-rich partially molten crust beneath the intrusive granites. We suggest that prior to porphyry mineralization, extension and erosion caused exhumation of these long-lived sulfide-bearing mush zones. This exhumation may have caused a change in magmatism style from volatile exsolution after the melts transited sulfide-bearing mushes (i.e., the BG), to volatile exsolution during magma transit through sulfide-bearing mushes (i.e., the OCG). We suggest that only the magmas and that exsolved fluids during their ascent through sulfide-bearing mushes were able to assimilate sufficient Cu-rich sulfides to fuel the formation of porphyry Cu deposits in the region.

Assessing the Scale Effect on Bearing Capacity of Undrained Subsoil: Implications for Seismic Resilience of Shallow Foundations.

This research investigates the influence of the scale effect on the bearing capacity of fine-grained subsoil under undrained conditions. The analyses were conducted based on laboratory tests of silty clay. Uniformly compacted samples were subjected to an unconfined compression test. The research was performed on cylindrical specimens. Three different variants of the diameter D (38 mm, 70 mm, 100 mm) and the corresponding height H = 2D were analyzed. Based on the tests results, the unconfined compression strength qu was determined, and from this, the undrained shear strength cu was calculated. The obtained results showed a clear decrease in cu with increasing sample size. However, in the existing reference documents, there are no specific guidelines for calculations of bearing capacity with consideration of sample size effect on the soil shear strength. Therefore, this study utilized the laboratory soil test data to calculate the bearing capacity of undrained subsoil, taking into account the seismic impacts, with a particular focus on spread foundations.

Effects of biostimulants on the morphological growth of cocoa seedlings at the nursery stage

Biostimulants help cocoa plants to improve vegetative development and nutrient uptake, therefore, the objective was to evaluate the effects of biostimulants on morphological growth in cocoa seedlings in nursery stage, through a completely randomized experimental design with four treatments (T1: control, T2: humic acids + fulvic acids, T3: silicon oxide + monosilicic acid; and T4: marine algae + humic and fulvic acids) and four replicates. The results showed no significant differences in variables such as plant height (T4: 29.63 cm), number of leaves (T2: 25.19) and root length (T2: 37.23 cm). Significant differences were found in stem diameter (T3: 7.08 cm) and root dry mass (T4: 8.67 g). The biostimulants showed positive results in nutritional elements at foliar level, improving the values of N, P, K, Zn, Mn, Mg, Ca and Fe. Likewise, there was a decrease in Cu and Na values. These results support the hypothesis that biostimulants help cocoa plants to improve vegetative development and nutrient uptake, reducing plant losses and improving plant nutrition at the nursery stage.

Study the Effects of the IL-1β -511 C>T Rs16944 SNP on the Incidence of Cardiomyopathy

Background: The diseases that involve the myocardium directly and are not the result of hypertension, congenital, vascular, coronary, or pericardial abnormalities are called cardiomyopathy (CM). It is known that interleukin-1 (IL-1) family cytokines involve in inflammation and immune regulation and act as an important role in innate and adaptive immunity. Aim: In this study, it was investigated the antioxidant capacity and their relation trace elements in cardiomyopathy CM patients and its correlation with IL-1β -511 C>T rs16944 SNP. Methods: TAOC, and Cu-Zn SOD were determined by ELISA, and Cu and Zn were assessed by spectrophotometric method. IL-1β -511 C>T rs16944 SNP was assessed by PCR and DNA sequencing. Results: The results were conducted that no statistically significant difference in age between CM and CONT groups (P>0.05). The results showed that was a statistically significant decrease in TAOC and SOD levels in the CM group compared to the CONT group (P<0.001). There was a statistically significant decrease in Cu and Zn levels in the CM group compared to the CONT group (P<0.001). Conclusion: This study suggested that the essential role of antioxidant capacity and their trace elements affected by IL-1β -511 C>T rs16944 SNP as a risk factor for the incidence of CM in the Iraqi population.

THE INFLUENCE OF THE LEVEL OF SOIL MOISTURE ON THE TRANSLOCATION OF Zn AND Cu IN GRAIN OF WINTER CEREALS IN THE CONDITIONS OF THE FOREST STEPPE OF THE RIGHT BANK

The attention of almost the entire world community is focused on the problem of food security. In many countries of the world, the lack of food resources is acutely felt, the main source of which is grain farming. Ukraine is distinguished among other countries by its favorable soil and climatic conditions for the cultivation of cereals, it has the appropriate technologies, and qualified workers. Therefore, the production of grain products is one of the main directions of the agro-industrial complex of Ukraine, which is subject to certain quality requirements. The article examines the influence of the level of soil moisture (precipitation and irrigation) on the content and coefficient of accumulation and danger of Zn and Cu in the grain of winter wheat and winter barley. The purpose of the study is to study the influence of the level of soil moisture (precipitation and irrigation) on the content of the coefficient of accumulation and danger of Zn and Cu in the grain of winter wheat and winter barley in the conditions of the right-bank forest-steppe. An increase in the coefficient of accumulation of Zn and a decrease in the coefficient of accumulation of Cu in cereal grains contributed to an increase in the concentration of Zn and a decrease in Cu under such conditions, this feature was established both in winter barley of the variety (Luran) and in winter wheat of the variety (Akratos). In particular, at the level of soil irrigation in the period of tillering-earing of winter barley and winter wheat from 256.2 mm to 272.5 mm, the concentration of Zn in the grain of these cereals was 1.07 times higher, and the concentration of Cu was 1.05 times lower in winter barley grain, and in winter wheat grain, the concentration of Zn was 1.14 times higher and 1.15 times lower than the concentration of Cu, respectively, compared to the moisture level of 47.4 mm and 52.3 mm. The coefficient of danger of heavy metals in the grain of winter cereals at the level of soil moisture from 256.2 mm. to 272.5 mm in the tillering-earing period was higher in Zn and lower in Cu compared to the moisture level of 47.4 mm–52.3 mm. An increase in the hazard ratio of Zn by 1.06 times and a decrease in the hazard ratio of Cu by 1.15 times in winter barley grains and an increase by 1.15 and a decrease by 1.16 times in winter wheat grains, respectively. During the artificial moistening of the soil during the growing season in the period of tillering-earing until the grain is milky, an increase in these Zn indicators and a decrease in Cu were observed in both winter barley and winter wheat grains.

Mineral phase transition characteristics and its effects on the stabilization of heavy metals in industrial hazardous wastes incineration (IHWI) fly ash via microwave-assisted hydrothermal treatment

Toxic heavy metals in industrial hazardous waste incineration (IHWI) fly ash can be effectively stabilized by using microwave-assisted hydrothermal technology. However, few works have focused on the relationship between mineralogical conversion and stability of heavy metals of fly ash during hydrothermal process. This study investigated the effect of mineral phase transition process on the stabilization and migration behavior of heavy metals in IHWI fly ash using coal fly ash as silicon‑aluminum additive. Mineral composition analysis reveals that after microwave-assisted hydrothermal treatment (MAHT) of IHWI fly ash, zeolite-like minerals (e.g., tobermorite, katoite and sodalite), secondary aluminosilicate minerals (e.g., prehnite and anorthite) and other newly-formed minerals (e.g., wollastonite, pectolite and larnite) were found. The leaching concentrations of heavy metals (Cr, Ni, Cu, Zn, Cd and Pb) in IHWI fly ash decrease sharply after MAHT with the most obvious decreases in Cu, Pb and Zn. Spearman correlation analysis show significantly negative correlation between the content of zeolite-like minerals and the leaching concentrations of most heavy metals (e.g., Ni, Cu, Zn, Cd and Pb). These results suggest that the immobilization effects of heavy metals in IHWI fly ash can be effectively enhanced by promoting the formation of zeolite-like minerals during the MAHT. This study is expected to further promote the development of IHWI fly ash harmless treatment technology.

Phytostabilization of trace elements and 13C isotope composition of Atriplex atacamensis Phil. cultivated in mine tailings treated with organic amendments.

Mining generates large quantities of mineral processing wastes that are typically stored in mine tailings (MT) ponds. Long-term exposure of the surrounding areas to the material from the tailings ponds has been reported to have adverse effects on both human health and the environment. The purpose of this study was to evaluate the ability of Atriplex atacamensis Phil. to phytostabilize metals (Cu, Fe, Mn, and Zn) and sulfur (S) when grown directly on mine tailings with and without compost (C) and humic substance (HS). The stress status of A. atacamensis Phil. was also evaluated through the 13C isotopic composition of bulk leaves. A 120-day greenhouse experiment was conducted and three treatments were evaluated: (i) MT without any amendments (control), (ii) MT + C (dose: 89 ton ha-1), and (iii) MT + HS (0.72 ton ha-1). Mine tailings material exhibited low salinity, alkaline pH, high extractable S-SO4 concentrations, and low fertility; total Fe, Mn, and Zn concentrations were within the reference range for mine tailings, but total Cu concentrations were high at 1860 ± 236mgkg-1. The HS had higher pH, EC, CEC, and available concentrations of N, P, and K than compost, while S-SO4 concentrations were similar in both amendments. 13C NMR analysis showed that the HS contained more alkyl, aromatic, and phenolic groups, while the compost was dominated by O-alkyl and carboxyl groups. At the end of the experiment, the MT + C treatment achieved a significant decrease in Cu, Fe, and Mn concentrations in the roots and aboveground parts of A. atacamensis Phil. and an increase in Zn values in both tissues. Both amendments increased the sulfur content in the aboveground parts, while metal concentrations under the HS treatment proved similar to control. Furthermore, the δ13CV-PDB values obtained in this study indicate that the organic amendments did not cause additional physiological stress to the plants compared to the MT treatment. Overall, A. atacamensis Phil. was shown to have the ability to phytostabilize metals and sulfur, making it a potential candidate species for in situ evaluation of the phytostabilization process on mine tailings.

Chalcophile element systematics of Mariana Trough basalts and implications for sulphide saturation evolution of intra-oceanic back-arc magmatic systems

ABSTRACT Magmatic sulphides largely control the behaviour of chalcophile elements in evolving magmas and also play critical roles in ore-forming processes at convergent plate margins. Magmas at the back-arc spreading centre of Mariana Trough are less affected by slab-derived fluids than Mariana arc basalts. However, whether the evolution of chalcophile elements in Mariana Trough magmas resembles or differs from those in arc magmas is poorly known. Based on the detailed petrological and geochemical studies, we present high-precision analyses of whole-rock chalcophile element (S, Cu, Ag, Re, Pd, Pt, Ru, Ir) contents for a suit of basaltic lavas (n = 15) from the central Mariana Trough. The occurrence of sulphides in high-Mg olivine crystals (Fo80) indicates that at least one episode of sulphide saturation occurred during early-stage magmatic evolution. The sulphur contents of most basalts were not significantly affected by degassing processes due to low oxidation state and high hydrostatic pressures. Instead, progressive fractionation of liquid sulphide with magmatic evolution is the dominant process, as reflected by sulphide petrography, the decrease in Cu, Ag, Pd, and Pt contents, and concomitant increase in Cu/Pd ratios (22,500–708,500), as well as nearly constant Cu/Ag (mean of 3137 ± 848, 1s) with decreasing MgO. We attribute early sulphide saturation of Mariana Trough basalts to their generation and evolution under relatively reducing conditions, with the limited effect of slab components. Combined with data from other island arc and back-arc lavas, we further show that the extent of adding slab-derived components, regardless of specific arc and back-arc tectonic settings, are determinants of the sulphide evolution and chalcophile element behaviour in magmatic systems above intra-oceanic subduction zones. Early magmatic sulphide saturation at central Mariana Trough would result in barren magmatic systems that are not suitable for the large-scale Cu-Au mineralization at the seafloor.

Nutrient transition metals in a time series of hydrothermal vent fluids from Main Endeavour Field, Juan de Fuca Ridge, Pacific Ocean

Cabled deep-sea observatories can deliver continuous power and communications linkages to seafloor instruments and sampling devices. Building on this capability, a nine-month time series of hydrothermal vent fluids was recently collected from the well-studied Main Endeavour Field on the Juan de Fuca Ridge (northeast Pacific Ocean) using a novel remotely triggered vent fluid sampling system connected to Ocean Network Canada's NEPTUNE observatory (Seyfried et al., 2022). These samples exhibit very low Mg concentrations (Mg = 0.19–3.07 mmol/kg), indicative of little-to-no contamination by ambient seawater, providing excellent insight into sub-seafloor hydrothermal processes. Here, we present analyses of these samples for transition metals identified as biological nutrients (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, and W) and identify possible controlling processes.Overall, nutrient transition metal concentrations in collected samples reflect dynamic responses to subtle deep-seated and near-surface changes in the hydrothermal system. Roughly two months into the deployment, inmixing of a Mg- and sulfate-rich fluid is decoupled from observed changes in vent fluid temperature but coincides with noticeable decreases in fluid Co and Mo concentrations, likely indicating subtle or more deep-seated cooling of the system and subsurface deposition of these temperature-sensitive metals. Several months later, a ∼20°C drop in vent fluid temperature from 304°C to 280–285°C over ∼20 hours is accompanied by ∼90% decreases in Cu, Zn, and Cd concentrations and an additional decrease in Mo attributable to precipitation of metal sulfides, presumably in the shallow subsurface. Relative stability in concentrations of other metals (V, Cr, Mn, Ni, W) suggests more deeply seated higher-temperature controls, though covariations in Cr and Ni concentrations decoupled from vent fluid temperature suggest subtle, temporally variable lithologic controls. Molybdenum concentrations (29–220 nmol/kg) are higher than expected based on previous analyses of seafloor hydrothermal vent fluids and do not reflect contamination by modern Mo-rich seawater. This finding has implications for understandings of hydrothermal Mo delivery to the ocean, relevant to hypotheses about the evolution of Mo-dependent biological pathways among early life forms in anoxic and Mo-poor ocean environments thought to be prevalent throughout the Archean Eon.

Use of Plant Growth-Promoting Bacteria and Humic Acids for Phytostabilization of Acid-Generating Mining Wastes

An interdisciplinary study was conducted on the effect of application of plant growth-promoting bacteria and humic acids in the reclamation of acid-generating mining wastes through a vegetation cover. The drainage water from the mining waste was characterized by a pH of 3.58 and high concentrations of sulfate, copper, manganese, and zinc. Strains of the Bacillus and Pseudomonas genera and humic substances produced by biotransformation from lignite were applied. The usage of plant growthpromoting bacteria and humic acid in the reclamation of acid-generating mining wastes produced several beneficial effects. The combined application resulted in a significant decrease in Cu, Fe, Zn and sulfate concentrations in a variety of drainage water samples, due to the suppression of pyrite oxidation. Both plant growth-promoting bacteria and humic acid improve plant growth, when used separately. The highest yield of fresh (between 22% and 43 %) and dry biomass of plants (between 31% and 41 %) was observed after combining both treatments, but the effect depended strongly on the dose of application. Yields of fresh and dry biomass in the combined application increased by treating plants with 0.42 g/kg humic acids, but decreased significantly when applying humic acids in a concentration of 0.84 g/kg soil. The treatment with a microbial consortium and humic substances enhanced significantly the uptake of nitrogen, phosphorus, and potassium by the plants. Furthermore, the addition of Bacillus and Pseudomonas bacteria in combination with humic acids to poor soil for reclamation reduced the Cu and Zn uptake.

Sulfur and chlorine budgets control the ore fertility of arc magmas

Continental arc magmas supply the ore-forming element budget of most globally important porphyry-type ore deposits. However, the processes enabling certain arc segments to preferentially generate giant porphyry deposits remain highly debated. Here we evaluate the large-scale covariation of key ore-forming constituents in this setting by studying silicate melt inclusions in volcanic rocks from a fertile-to-barren segment of the Andean Southern Volcanic Zone (33–40 °S). We show that the north-to-south, fertile-to-barren gradient is characterized by a northward increase in S and Cl concentrations and a simultaneous decrease in Cu. Consequently, we suggest that the concentration of S and Cl rather than the concentration of ore metals regulates magmatic-hydrothermal ore fertility, and that the loss of volatiles prior to arrival in the upper crust impacts ore-forming potential more than magmatic sulfide saturation-related ore metal scavenging.

Environmental and dietary determinants of metal exposure in four-year-old children from a cohort located in an industrial area (Asturias, Northern Spain)

Urine samples from four-year-old children located in a heavily industrialized zone in Asturias (Spain) were collected between 2009 and 2012 (n = 334). Vanadium (V; median 54 μg/g creatinine), cobalt (Co; 1.0 μg/g c.), nickel (Ni; 3.8 μg/g c.), copper (Cu; 22 μg/g c.), zinc (Zn; 590 μg/g c.), arsenic (As; 64 μg/g c.), selenium (Se; 49 μg/g c.), molybdenum (Mo; 110 μg/g c.), cadmium (Cd; 0.27 μg/g c.), antimony (Sb; 1.0 μg/g c.), cesium (Cs; 14 μg/g c.), barium (Ba; 2.6 μg/g c.), thallium (Tl; 0.55 μg/g c.) and lead (Pb; 1.9 μg/g c.) were analysed. Comparison with children from other sites showed that this Asturias cohort was characterized by high levels of V, As, Sb, Cs and Tl. The concentrations of Co, Ni, Zn, Cu, Mo, Se, Cd, Ba and Pb were within the range of other cohorts.Terrestrial dietary items were most strongly related to increased urinary concentrations of metals in children, e.g., red meat with Ba and Ni, pasta/cereal with Ni and Zn, sweets with Zn, Co, and Cu, eggs with Mo, Cd, and Cs, and dairy products with Co and Sb. Seafood was the second group of dietary items significantly related to increased metals, e.g., shellfish with Ba, Cs, Pb, and V, fatty fish with As, and lean fish with As and Se.In contrast, higher fruit intake was significantly associated with decreased Cu and Sb, and higher legume intake with decreased Cu, Se and Cs. Higher intakes of other dietary items also led to significant decreases in some metals, such as vegetables and lower concentrations of Se and Mo, and dairy products with decreases in Cu and As. These negative correlations implied very low concentrations of the mentioned metals in these foods.Higher exposure to traffic was associated with higher concentrations of Ba, present in brake components. Children living outside urban areas had higher concentrations of Se. No association of metals with smoking in the family was found.

Performance Research of PVA (Polyvinyl alcohol) Based on HKUST-1 as Additive

We report a 98.8% UV light barrier, water resistant and better mechanical performance PVA membrane based on 5% HKUST-1 as UV protection additive, and compared with ZnO and UV 531. X-ray photoelectron spectroscopy (XPS) revealed binding energy decrease of Cu 2p3/2 and Cu 2p1/2, to be 1.2 eV and 1.4 eV, respectively, which indicates Cu2+ partially converted to Cu+ in the presence of residual C in PVA during UV irradiating, very different from that of ZnO which can be ascribed to diffused reflection.

Impacts of KF Post-Deposition Treatment on the Band Alignment of Epitaxial Cu(In,Ga)Se2 Heterojunctions.

In this study, we investigated band alignments at CdS/epitaxial CuInxGa1-xSe2 (epi-CIGSe) and epi-CIGSe/GaAs heterointerfaces for solar cell applications using ultraviolet, inverse, and X-ray photoemission spectroscopy (UPS, IPES, and XPS) techniques. We clarified the impacts of KF postdeposition treatment (KF-PDT) at the CdS/epi-CIGSe front heterointerfaces. We found that KF-PDT changed the conduction band alignment at the CdS/epi-CIGSe heterointerface from a cliff to flat configuration, attributed to an increase in the electron affinity (EA) and ionization potential (IP) of the epi-CIGSe surface because of a decrease in Cu and Ga contents. Herein, we discuss the correlation between the impacts of KF-PDT and the solar cell performance. Furthermore, we also investigated the band alignment at the epi-CIGSe/GaAs rear heterointerface. Electron barriers were formed at the epi-CIGSe/GaAs interface, suppressing carrier recombination as the back surface field. Contrarily, a hole accumulation layer is formed by the valence band bending, which is like Ohmic contact.

Label-free electrochemical aptasensor for rapid detection of SARS-CoV-2 spike glycoprotein based on the composite of Cu(OH)2 nanorods arrays as a high-performance surface substrate

The development of advanced electrode materials and the combination of aptamer with them have improved dramatically the performance of aptasensors. Herein, a new architecture based on copper hydroxide nanorods (Cu(OH)2 NRs) are directly grown on the surface of screen printed carbon electrode (SPCE) using a two-step in situ, very simple and fast strategy and was used as a high-performance substrate for immobilization of aptamer strings, as well as an electrochemical probe to development a label-free electrochemical aptasensor for SARS-CoV-2 spike glycoprotein measurement. The Cu(OH)2 NRs was characterized using X-ray Diffraction (XRD) and electron microscopy (FESEM). In the presence of SARS-CoV-2 spike glycoprotein, a decrease in Cu(OH)2 NRs-associated peak current was observed that can be owing to the target-aptamer complexes formation and thus blocking the electron transfer of Cu(OH)2 NRs on the surface of electrode. This strategy exhibited wide dynamic range in of 0.1 fg mL−1 to 1.2 µg mL−1 and with a high sensitivity of 1974.43 μA mM−1 cm−2 and low detection limit of 0.03 ± 0.01 fg mL−1 of SARS-CoV-2 spike glycoprotein deprived of any cross-reactivity in the presence of possible interference species. In addition, the good reproducibility, repeatability, high stability and excellent feasibility in real samples of saliva and viral transport medium (VTM) were found from the provided aptasensor. Also, the aptasensor efficiency was evaluated by real samples of sick and healthy individuals and compared with the standard polymerase chain reaction (PCR) method and acceptable results were observed.

Effectiveness of Adsorbents Chicken Eggshells and Cassava Skin to Reduce Pollutants in the Electroplating Industry

The electroplating industry has toxic content that is toxic to living things and the environment. This study aims to examine the values of Cu and Cr levels in the electroplating industry based on variations in adsorbent weight comparison. Adsorbents used are chicken eggshell and cassava skin with a contact time of 90 minutes. Adsorbent comparison used is 20:10, 25:10, and 30:10. After processing by applying the adsorbent system in the electroplating industry wastewater obtained the results of research it appears that the comparison of the weight of adsorbents influenced the decline of Cu and Cr metals with a decrease in Cu by 0.003 mg/l or with the efficiency of 99.43% and a decrease in Cr by 0.962 mg/l or with an efficiency of 95.44%.

Effects of composition and thermal treatment on VOC‐limiting defects in single‐crystalline Cu2ZnSnSe4 solar cells

AbstractSingle‐crystalline Cu2ZnSnSe4 (CZTSe) solar cells with open circuit voltages reaching 500 mV are achieved through a combination of composition control and a low‐temperature thermal ordering treatment. A comparison of the device results for Cu‐poor CZTSe with Cu/Zn + Sn ratios of 0.77 and 0.86 is presented with and without the implementation of a 130°C absorber annealing treatment. An increase in bandgap energy is observed via external quantum efficiency measurements with both the decrease in Cu content and the implementation of the order anneal, the latter of which also leads to a decrease in Urbach energy. Defect characterization performed with admittance spectroscopy on devices is demonstrated as insufficient because of low‐temperature current barriers. Photoluminescence (PL) on crystal surfaces however enables a qualitative comparison of the defect landscape between crystal compositions and annealing treatments. Both a highly compensated and a lightly doped defect model are used to fit PL as a function of laser fluence to identify defects contributing to each observed recombination channel. The PL signatures attributed to the ZnSn defect become unresolvable with a decrease in Cu/Zn + Sn ratio from 0.86 to 0.77. Furthermore, a decrease in Cu–Zn disorder is observed upon the implementation of the annealing treatment through both a comparison of potential fluctuation depths and of both PL models.

Significantly Improved Colossal Dielectric Properties and Maxwell-Wagner Relaxation of TiO2-Rich Na1/2Y1/2Cu3Ti4+xO12 Ceramics.

In this work, the colossal dielectric properties and Maxwell—Wagner relaxation of TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 (x = 0–0.2) ceramics prepared by a solid-state reaction method are investigated. A single phase of Na1/2Y1/2Cu3Ti4O12 is achieved without the detection of any impurity phase. The highly dense microstructure is obtained, and the mean grain size is significantly reduced by a factor of 10 by increasing Ti molar ratio, resulting in an increased grain boundary density and hence grain boundary resistance (Rgb). The colossal permittivities of ε′ ~ 0.7–1.4 × 104 with slightly dependent on frequency in the frequency range of 102–106 Hz are obtained in the TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 ceramics, while the dielectric loss tangent is reduced to tanδ ~ 0.016–0.020 at 1 kHz due to the increased Rgb. The semiconducting grain resistance (Rg) of the Na1/2Y1/2Cu3Ti4+xO12 ceramics increases with increasing x, corresponding to the decrease in Cu+/Cu2+ ratio. The nonlinear electrical properties of the TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 ceramics can also be improved. The colossal dielectric and nonlinear electrical properties of the TiO2–rich Na1/2Y1/2Cu3Ti4+xO12 ceramics are explained by the Maxwell–Wagner relaxation model based on the formation of the Schottky barrier at the grain boundary.

Undrained shear strength of polypropylene fiber reinforced alluvial clay

Construction of civil engineering structures on weak soil without taking necessary precautions may be risky. Alluvial soil that has not completed its geological formation has a high void ratio and contains organic material therefore, the strength properties of these soils should be examined carefully. In this study, the undrained shear strength (cu) behavior of natural and polypropylene (PP) fiber-reinforced alluvial clays was investigated with a laboratory Vane shear test. To examine the moisture content effects on cu behavior of alluvial clay, samples were prepared in 0.50 liquid limit (LL), 0.75 LL, and LL water contents. The PP fibers used were 6 and 18 mm long, they mixed with soil 0.1, 0.5, and 1% by dry weight of the sample. The Vane shear tests were performed at two different depths to investigate the overburden pressure effect. The increase in water content caused a significant decrease in cu. The laboratory results indicated that the cu of PP reinforced (1 % and 18 mm PP) alluvial clay deposits prepared in 0.5LL, 0.75LL, and LL water contents were 56.6, 20.7, and 8.4 kPa, respectively. The increase in PP fiber content increased the cu of alluvial clay deposits. The length of fiber was directly proportional to cu values. The effect of fiber was more pronounced in long fiber added samples. The cu of natural and %1 fiber reinforced (6 mm and 18 mm) samples prepared in the same water content were 27.4, 29.1, and 55.7 kPa. The cu increased with increasing penetration depth.