Search Results (15,795)

Four quaternary Zintl phase thermoelectric (TE) materials belonging to the Ba_1-xEu_xZn₂Sb₂ (x = 0.02(1), 0.04(1), 0.08(1), 0.15(1)) system were successfully synthesized using the molten Pb-flux or the conventional high-temperature reaction methods. Their crystal structures were characterized by both powder and single-crystal X-ray diffraction analyses, and all four isotypic title compounds adopted the orthorhombic BaCu₂S₂-type (Pnma, Z = 4, Pearson code oP20) structure. The radius ratio criterion, based on the cationic and anionic elements (i.e., r₊/r₋), was successfully verified in the title system, as in our previous reports, where r₊/r₋ > 1 for the BaCu₂S₂-type structure. A series of density functional theory calculations were performed using a hypothetical model with the idealized compositions of Ba_0.75Eu_0.25Zn₂Sb₂, and the results were compared with the ternary parental compound BaZn₂Sb₂ to understand the influence of Eu substituents in the Ba_1-xEu_xZn₂Sb₂ system. A similar overall shape of the density of states (DOS) curves and the near-constant DOS values at E_F before and after the cationic substitution suggest only marginal changes in the carrier concentration. Therefore, carrier mobility has a dominant role in rationalizing the observed variations in the electrical transport properties of the title system. Temperature-dependent TE property measurements proved that an increase in the Seebeck coefficient S and a decrease in electrical conductivity σ were observed as the Eu substituents gradually increased in the Ba_1-xEu_xZn₂Sb₂ system, although the overall S and σ values were lower than those in the parental compound BaZn₂Sb₂. The thermal conductivities of these title compounds were successfully lowered by phonon scattering, but due to the overall smaller electrical transport properties, the observed maximum ZT was 0.49 at 773 K for Ba_0.98(1)Eu_0.02Zn₂Sb₂. Full article

Waterholes in semi-arid environment are sections of rivers that fill during high river flows or floods and keep water once flow ceases. They are essential water sources for rive ecosystems. Some waterholes remain even during prolonged droughts. The resilience of ecosystems in these environments depends on the persistence of the waterholes. While most semi-arid, ephemeral river systems are disconnected from regional groundwater and losing in most parts there may be some sections that can be connected to localised groundwater or parafluvial areas. To assess the persistence of waterholes the groundwater contribution to the water balance needs to be addressed. This study assesses groundwater connectivity to waterholes in a part of the Murray-Darling Basin, one of the largest watersheds in the world, using environmental tracers radon and stable isotopes. Approximately 100 samples were collected from 27 waterholes along the Narran, Calgoa, Barwon and Darling rivers, as well as 8 groundwater bore samples. The assessment of groundwater connectivity or the lack of is necessary from water balance modelling and estimation of persistence of these waterholes. As expected, the results indicate consistently low radon concentrations in the waterholes and very small deviation in stable isotopes ${\delta }^{18}$O and ${\delta }^2$H. In general, most of these waterholes are losing water to groundwater, indicated by low salinity (EC values) and low radon concentrations. While radon concentrations are small in most cases and indicative of little groundwater contributions, some variability can be assigned to bank return and parafluvial flow. It indicates that these contributions may have implications for waterhole persistence in ephemeral streams. The study demonstrates that in some cases local bank return flow or parafluvial flow may contribute to waterhole persistence. Full article

Perovskite solar cells (PSCs) characterized by high energy conversion efficiency (ECE) and low manufacturing costs, exhibit promising potential for commercialization in the near term. For commercialization, it is very important to prevent the decomposition of perovskite by ultraviolet (UV) radiation in the air environment. Also, the mesoscopic architecture of PSCs presents considerable opportunities for the solar cell industry, offering potential for recycling of spent photocatalytic materials such as TiO₂, and exploration of new energy resources. To solve these problems, therefore, this study introduces a strategy to mitigate these challenges using a crystalline Al-doped TiO₂ buffer layer as the electron transport layer (ETL) in conjunction with a mesoporous TiO₂ layer in the fabrication of PSCs. Among various Al concentrations in the crystalline Al-doped TiO₂ buffer layer fabricated via spin-coating, an optimum concentration of 7 mol% Al yielded the highest cell performance in the specific perovskite solar cell structure. These solar cells exhibited an impressive ECE of 11.87%, representing a substantial enhancement of nearly double the ECE (6.37%) achieved with the conventional ETL. This remarkable improvement can be attributed to the passivation effect of the newly developed ETL, which combines a crystalline Al-doped TiO₂ buffer layer with a mesoporousTiO₂ layer. Electrochemical impedance spectroscopy (EIS) analysis was performed in conjunction with theoretical calculations of charge transport parameters to substantiate this claim. Full article

Mine tailings are a byproduct of mineral extraction and often pose an environmental challenge due to the contamination of soil and water bodies with dissolved metals. However, this type of waste offers the opportunity for the recovery of valuable metals such as silver (Ag). In the present investigation, an integral analysis of a sample of tailings was carried out, addressing granulometry, elemental composition, neutralization potential (NP), and acid potential (AP), as well as mineralogy, for the dissolution of silver from this type of waste. For this purpose, thiourea (CH₄N₂S) was used as a leaching agent due to its low toxicity, and potassium oxalate (K₂C₂O₄) was used as an organic additive to improve the leaching of the silver phases (argentite and polybasite) present in the tailings. The effects of CH₄N₂S and K₂C₂O₄ concentrations, temperature, and pH on the leaching efficiency of silver (Ag), copper (Cu), iron (Fe), and arsenic (As) were systematically studied. The results revealed that the maximum silver dissolution rate reached 90.75% under optimal conditions: 0.2 M L⁻¹ of thiourea and 0.2 M L⁻¹ of potassium oxalate, at 35 °C and a pH of 2. Full article

Investigation of the critical metal elements in coal and coal-bearing strata has become one of the hottest research topics in coal geology and coal industry. Coal-hosted Ga-Al-Li-REE deposits have been discovered in the Jungar and Daqingshan Coalfields of Inner Mongolia, China. Gallium, Al, and Li in the Jungar coals have been successfully extracted and utilized. This paper reviews the discovery history of coal-hosted Ga-Al-Li-REE deposits, including contents, modes of occurrence, and enrichment origin of critical metals in each coal mine, including Heidaigou, Harewusu, and Guanbanwusu Mines in the Jungar Coalfield and the Adaohai Coal Mine in the Daqingshan Coalfield, as well as the recently reported Lao Sangou Mine. Gallium and Al in the coals investigated mainly occur in kaolinite, boehmite, diaspore, and gorceixite; REEs are mainly hosted by gorceixite and kaolinite; and Li is mainly hosted by cholorite. Gallium, Al, and REEs are mainly derived from the sediment-source region, i.e., weathered bauxite in the Benxi Formation. In addition, REE enrichment is also attributed to the intra-seam parting leaching by groundwater. Lithium enrichment in the coals is of hydrothermal fluid input. The content of Al₂O₃ and Ga in coal combustions (e.g., fly ash) is higher than 50% and ~100 µg/g, respectively; concentrations of Li in these coals also reach the cut-off grade for industrial recovery (for example, Li concentration in the Haerwusu coals is ~116 µg/g). Investigations of the content, distribution, and mineralization of critical elements in coal not only provide important references for the potential discovery of similar deposits but also offer significant coal geochemical and coal mineralogical evidence for revealing the geological genesis of coal seams, coal seam correlation, the formation and post-depositional modification of coal basins, regional geological evolution, and geological events. Meanwhile, such investigation also has an important practical significance for the economic circular development of the coal industry, environmental protection during coal utilization, and the security of critical metal resources. Full article

Dissolved organic matter (DOM) exerts a crucial role in biogeochemical processes and ascertaining water quality in reservoirs, where it is vulnerable to the dynamic impacts of surface water inflows. However, understanding how DOM quantity and biochemical features responds to hydrodynamic forces in tropical reservoirs remains limited. To enhance our understanding of the vertical profiles of DOM characteristics under varying hydrodynamic forces (strong, moderate, and weak regions) in the Chitian Reservoir (18°43′–18°42′ N, 109°68′–109°70′ E), in December 2023, we investigated the concentrations and biochemical characteristics of water column DOM samples using multispectral techniques, a parallel factor model, and two-dimensional correlation analysis. Our results indicated that DOM concentrations (4.34 ± 0.36 mg/L) are the highest in the reservoir center, whereas total nitrogen (0.52 ± 0.04 mg/L), total phosphorus (0.02 ± 0.03 mg/L), and nitrate nitrogen (1.01 ± 0.07 mg/L) present their highest values in the inlet region. As hydrodynamic force decreases, microbial activity increases, whereas DOM’s humification degree and molecular weight decline. DOM in the Chitian Reservoir comprises humic-like components, including three terrestrial sources (accounting for 85.38%~87.03%) and one microbial source, with dominant characteristics of allochthonous origin. The relative abundance of microbial components decreased from 14.62% to 12.97% with the increasing hydrodynamic force and increased with depth. DOM functional groups in the strong hydrodynamic force region and the reservoir’s upper layer show high consistency and uniformity. Phenolic O–H is the most reactive functional group concerning changes in water depth across all hydrodynamic areas, followed by polysaccharide C–O, owing to its high photoactivity. In contrast, aromatic C–H demonstrates the weakest reactivity. DOM’s spectral features are closely linked to nutrient form concentrations (N and P). Full article

Litchi fruit (Litchi chinensis Sonn.) is highly perishable because its shelf life is significantly limited by pericarp browning and microbial spoilage. While sulfur dioxide (SO₂) fumigation has been traditionally used to preserve color and reduce spoilage, concerns over potential health risks have prompted the exploration of safer alternatives. This study investigated the application of hypochlorous acid (HClO) as an alternative treatment during postharvest processes to mitigate pathological decay, targeting Mucor lusitanicus, a fungus primarily responsible for litchi fruit rot in Taiwan. In vitro experiments demonstrated that M. lusitanicus growth was completely inhibited by HClO concentrations at 40 mg L⁻¹ or higher, as well as by temperatures below 1 °C. In vivo experiments further revealed that disease symptoms in inoculated litchi fruit were fully suppressed at 25 °C for seven days after hydrocooling with HClO. When 40 mg L⁻¹ HClO treatment was combined with hydrocooling and subsequent storage at 5 °C, the decay ratio of litchi fruit was reduced to below 3% after 21-day storage. The browning index and disease incidence of litchi fruit hydrocooled with an 8 h hydrocooling delay were significantly lower than those with a 12 h hydrocooling delay after 21 days at 5 °C, followed by 1 day at 26 °C. Therefore, hydrocooling within 8 h of harvest is recommended for commercial scales. This treatment effectively prevented pericarp browning and maintained total soluble solid levels, ensuring the quality. These findings suggest that integrating HClO with hydrocooling not only decreases spoilage and delays pericarp browning but also offers a viable alternative to traditional SO₂ fumigation, optimizing the postharvest process and enhancing food safety. This approach can extend the storage ability of litchi fruit while maintaining its quality, providing a safer method for local and international markets. Full article

Molybdenum (Mo) is widely used as a micronutrient fertilizer to improve plant growth and soil quality. However, the interactions between cell wall biosynthesis and molybdenum have not been explored sufficiently. This study thoroughly investigated the regulatory effects of different concentrations of Mo on tobacco cell wall biosynthesis from physiological and metabolomic aspects. The results indicate that Mo treatment increased the Mo content of tobacco variety K326. Moreover, it significantly up-regulated the gene expression levels of molybdases (NR, AO, SO, XDH) and molybdate transporters in tobacco, whereby the gene expression levels of NR were upregulated by 28.48%, 52.51%, 173.05%, and 246.21%, respectively; and MOT1 and MOT2 were upregulated by 21.49/8.67%, 66.05/30.44%, 93.05/93.26%, and 166.11/114.29%, respectively. Additionally, Mo treatment regulated the synthesis of related enzymes, effectively promoted plant growth, and significantly increased biomass and dry matter accumulation, with the biomass in the leaves increasing significantly by 30.73%, 40.72%, 46.34%, and 12.88%, respectively. The FT-NIR spectroscopy results indicate that after Mo was applied to the soil, the quantity of C-O-C, -COOH, C-H, and N-H functional groups increased. Concurrently, the contents of cellulose, hemicellulose, lignin, protopectin, and soluble pectin in the leaves significantly increased, wherein the content of soluble pectin and hemicellulose increased significantly by 31.01/288.82%, 40.69/343.43%, 69.93/241.73%, and 196.88/223.26%, respectively. Furthermore, the cell walls thickened, increasing the ability of the plant to withstand disturbances. The metabolic network diagrams indicate that Mo regulated galactose metabolism, and arginine and proline acid biosynthesis. The contents of carbohydrates, spermidine, proline, quinic acid, IAA, flavonoids, and other substances were increased, increasing the levels of polysaccharides and pectin within the cell wall, controlling lignin production, and successfully enhancing resistance to abiotic stress. These results offer important perspectives for further investigations into the role of trace elements. Full article

In this study, an attempt was made to micropropagate the Siberian motherwort (Leonurus sibiricus L.) in in vitro cultures. The aim of this study was to compare methods of sterilization of seeds, which served as a source of initial explants to induce in vitro culture and to multiply shoots from explants isolated from them. The primary explants in the experiment were seeds. The seeds were placed on ½ MS medium without PGR and enriched with GA₃ at a concentration of 1 mg∙dm⁻³. The addition of GA₃ to the medium stimulated their germination. Sodium hypochlorite (NaClO) and 70% ethanol (C₂H₅OH) were used to sterilize the seeds. NaClO was used for proper sterilization in concentrations: 0.0% (1), 1.5% (2), 2% (3), and 2.5% (4) for 11 min. As secondary explants in the experiment, single-node fragments of sterile seedlings derived from sterile seeds were used, which were placed on MS medium, with the addition of plant growth regulators (PGR) from the group of auxins and cytokinins. The largest number of sterile and live Siberian motherwort seedlings was obtained in the variant in which 2.5% NaClO was used for proper sterilization of the seeds. To optimize the procedure of in vitro micropropagation, the axillary shoots of Leonurus sibiricus L. were transferred during the third passage onto nine different combinations of MS medium: PGR-free medium, with different concentrations of BAP (6-benzylaminopurine) (0.0, 2.0, 3.0, 4.0, 5.0 mg∙dm⁻³) and BAP (0.0, 2.0, 3.0, 4.0, 5.0 mg∙dm⁻³) with NAA (1-naphthaleneacetic acid) (1.0 mg∙dm⁻³). The largest number of shoots (9.62) forming was obtained on the medium supplemented with 4 mg∙dm⁻³ BAP and 1 mg∙dm⁻³ NAA, while the longest shoots were on the medium without PGR. Induction of rhizogenesis of Siberian motherwort plants in in vitro cultures was achieved on MS medium with the addition of 0.5 mg∙dm⁻³ IAA (indole-3-acetic acid). At the stage of adaptation to ex vitro conditions, high plant survival of 90% was achieved by using a solution with MS salts (25%) for irrigation. Full article

Honey is abundant in bioactive compounds, which demonstrate considerable therapeutic effects, particularly on oxidative stress and inflammation. Objectives: This work sought to evaluate the antioxidant mechanisms of Manuka honey (MH) and Ohia Lehua honey (OLH), correlating them with phytochemical analyses in a rat model of experimentally induced inflammation. Methods: The identification of polyphenolic compounds in the extracts was carried out using HPLC-ESI MS. The extracts’ antioxidant activity was evaluated in vitro through DPPH, FRAP, H₂O₂, and NO scavenging assays, while in vivo assessments included measurements of total oxidative status (TOS), total antioxidant capacity (TAC), oxidative stress index (OSI), advanced oxidation protein products (AOPP), malondialdehyde (MDA), nitric oxide (NO), and total thiols (SH). Results: The phytochemical analysis found a rich content of phenolic compounds in MH and lower quantities in OLH. In terms of in vitro activity, both MH and OLH exhibited strong DPPH radical scavenging abilities, effective NO and H₂O₂ scavenging capacities, and high FRAP-reducing power. In vivo, OLH proved highly effective in enhancing antioxidant capacity and lowering oxidative stress markers, showing significant increases in TAC and substantial reductions in TOS and OSI levels. Conversely, MH displayed limited and dose-dependent antioxidant activity, a considerable increase in TAC and SH, and a moderate decrease in TOS and OSI levels. Conclusions: To our knowledge, this is the first study to assess the phenolic content of OLH and to show its capacity to scavenge free radicals and reduce oxidative stress. The effectiveness of MH primarily relies on its increased antioxidant properties and depends on concentration. These results highlight the importance of investigating natural products in developing antioxidant strategies. Full article

Background/Objectives: Cold atmospheric plasma (CAP) has been demonstrated as an adjustable device to generate various combinations of short-lived reactive oxygen and nitrogen species (RONS) and as a promising appliance for cancer therapy. This study investigated the effects of direct and indirect treatments of Argon-based CAP to cancer cells (A2058, A549, U2OS and BCC) and fibroblasts (NIH3T3 and L929) on cell viability. We also aimed to understand whether plasma-generated RONS were involved in this process using genetic evidence. Methods: The intensity of reactive species in the plasma gas and the concentrations of RONS in phosphate-buffered saline (PBS) and cell culture medium were measured. A viability assay was performed after the cells were treated by plasma in PBS and medium with various volumes to realize the lethal effects of plasma under different conditions. Diverse cells were treated in the same solution to compare the sensitivities of different cells to plasma treatments. The gene expression profiles of A2058 cells after the direct and indirect treatments were analyzed by next generation gene sequencing. Accordingly, we discovered the advantages of sequential treatments on cancer therapy. Results: The cumulative concentration of hydroxyterephthalic acid (HTA) revealed that the pre-existing OH radical (•OH) in PBS increased with the treatment durations. However, there was no significant increase in the concentration of HTA in culture medium. HTA was detected in the treatment interface of PBS but not medium, showing the penetration of •OH through PBS. The concentrations of H₂O₂ and NO₂⁻ increased with the treatment durations, but that of NO₃⁻ was low. The direct treatments caused stronger lethal effects on cancer cells under certain conditions. The fibroblasts showed higher tolerance to plasma treatments. From gene expression analysis, the initial observations showed that both treatments influenced transcription-related pathways and exhibited shared or unique cellular stress responses. The pre-treatments, especially of direct exposure, revealed better cancer inhibition. Conclusions: The anti-cancer efficiency of plasma could be enhanced by pre-treatments and by adjusting the liquid interfaces to avoid the rapid consumption of short-lived RONS in the medium. To achieve better therapeutic effects and selectivity, more evidence is necessary to find optional plasma treatments. Full article

The present research aimed to assess the anti-cancer effects of the polysaccharide fraction (SJP) isolated from Saccharina japonica. The release of immune-activating cytokines, including IL-6, IL-12, and TNF-α, was markedly stimulated by the SJP in a concentration-dependent manner within the range of 1 to 100 µg/mL. Furthermore, the prophylactic intravenous (p.i.v.) and per os (p.p.o.) injection of SJP boosted the cytolytic activity mediated by NK cells and CTLs against tumor cells. In a study involving Colon26-M3.1 carcinoma as a lung cancer model, both p.i.v. and p.p.o. exhibited significant anti-lung-cancer effects. Notably, p.i.v. and p.p.o. administration of SJP at a dose of 50 mg/kg reduced tumor colonies by 84% and 40%, respectively, compared to the control. Moreover, the anti-lung-cancer effects of SJP remained substantial, even when NK cell function was inhibited using anti-asialo-GM1. Fractionation with CaCl₂ suggested that SJP is a mixture of alginate and fucoidan. The fucoidan fraction stimulated the immune response of macrophages more strongly than the alginate fraction. Consequently, this finding suggested that SJP from S. japonica possesses remarkable anti-cancer effects through the activation of various immunocytes. In addition, this finding indicates that the potent biological activity of SJP may be attributed to fucoidan. Full article

The study aimed to evaluate the cold tolerance of various peach cultivars under diverse low-temperature conditions (−5, −10, −15, −20, −25, −30, and −35 °C). A comprehensive assessment of their responses to cold was performed by integrating LT50 values with membership functions and evaluating local adaptability among the selected peach cultivars. The findings revealed that as temperatures dropped, electrical conductivity (REC), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) levels initially rose, then fell, and subsequently increased once more. Soluble sugar (SS) and soluble protein (SP) concentrations peaked at −25 °C and showed a significant negative correlation with semi-lethal temperature (LT50). The expression of free proline varied among different samples. Combining physiological analyses with field adaptation correlation assessments, it was found that ‘Ziyan Ruiyang’ exhibited a relatively low LT50 value of −29.67 °C and a membership function degree of 0.76, suggesting robust field adaptation abilities. At the same time, ‘Ganlu Shumi’ demonstrated stable trends in H₂O₂ and MDA levels, maintaining them at relatively low concentrations; it also had the lowest LT50 value, the highest membership function score, and the highest survival rate. Consequently, this cultivar could be a valuable resource for enhancing cold resistance under low-temperature stress. In summary, by correlating LT50 values with membership functions and observing local adaptability in these peach cultivars, we have established reliable data that can serve as a basis for identifying potential cross-breeding parents to develop new cold-resistant varieties. Full article

This study evaluated the antioxidant efficacy of ellagitannins from a pomegranate husk in preventing vegetable canola oil (VCO) oxidation during French fry preparation. Ellagitannins were extracted using 80% acetone, purified via Amberlite XAD-16 resin chromatography, and incorporated into VCO at 0.05%, 0.1%, and 0.2% concentrations. VCO oxidation was assessed at 145 °C, 160 °C, and 190 °C, with frying experiments conducted at 160 °C for five 10 min cycles. Primary lipid oxidation (peroxide values) was measured using the AOCS Cd 8-53 method, and molecular structural changes were analyzed by infrared spectroscopy. Results showed that ellagitannins significantly mitigated VCO oxidation across all temperatures, with 0.05% identified as the optimal concentration. This concentration reduced peroxide values to 4.66 ± 1.15 meq O/kg, remaining stable and below acceptable limits during frying. Infrared spectroscopy confirmed no significant structural changes in VCO. These findings highlight ellagitannins as effective antioxidants for enhancing VCO oxidative stability during frying, offering a natural, sustainable solution for improving oil quality and extending its usability in the food industry. Full article

Pollution of freshwater by synthetic organic dyes is a major concern due to their high toxicity and mutagenicity. In this study, the degradation of Congo red (CR) and malachite green (MG) dyes was investigated using nanostructured Gd₂O₃. It was prepared using the coprecipitation method, using gadolinium nitrate and concentrated formic acid, with subsequent calcination at 600 °C. Its morphology corresponds to hollow porous microspheres with a size between 0.5 and 7.5 μm. The optical bandgap energy was determined by using the Tauc method, giving 4.8 eV. The degradation of the dyes was evaluated by UV-vis spectroscopy, which revealed that dissociative adsorption (in the dark) played a key role. It is explained by the cleavage and fragmentation of the organic molecules by hydroxyl radicals (^•OH), superoxide radicals (^•${\mathrm{O}}_2^{-}$) and other reactive oxygen species (ROS) produced on the surface of Gd₂O₃. For CR, the degradation percentage was ~56%, through dissociative adsorption, while UV light photocatalysis increased it to ~65%. For MG, these values were ~78% and ~91%, respectively. The difference in degradation percentages is explained in terms of the isoelectric point of solid (IEPS) of Gd₂O₃ and the electrical charge of the dyes. FTIR and XPS spectra provided evidence of the role of ROS in dye degradation. Full article