Search Results (77)

In the recycling of semiconductor materials like Bi₂Te₃ or CdTe, TeO₂ may form as a by-product that can be directly reduced to recover metallic Te. The hydrogen reduction of TeO₂ offers an eco-friendly alternative to conventional carbothermic reduction by avoiding CO by-products. This study investigates the reduction of 99.99 wt.% purity level TeO₂ using hydrogen in an oscillating kiln furnace (200–800 °C, 2–7 h), with phase composition and microstructure analysed via XRD and SEM. Results demonstrate conversions of up to 89% (solid–gas) and 100% (liquid–gas), revealing that kinetics dominate over thermodynamics in controlling reaction progress. The work proposes a reaction mechanism based on morphological evolution observed in SEM images, suggesting that further parameter optimisation could enhance scalability. As the first lab-scale demonstration of hydrogen-assisted TeO₂ reduction, this study establishes a preliminary process window (temperature/time) and underscores the potential for industrial adoption. Future work should verify the proposed mechanism and refine operational parameters to maximize efficiency. Full article

Silver nanoparticles belong to a highly versatile group of nanomaterials with an appealing range of potential applications. In the realm of antimicrobial and antioxidant application, silver nanoparticles (AgNPs) exhibit auspicious capabilities. This research, for the very first time, endeavors to carry out biosynthesis of AgNPs coupled with fermentation using Medusomyces gisevii and Origanum vulgare L. (O. vulgare) plant species. Fermentation (F) via Medusomyces gisevii is responsible for chemical, physical, biological, and electrochemical processes. During in vitro study of antioxidant activity, fermented O. vulgare herb extract showed strong reductive activity as evaluated by the cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP), and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) assay, with a value of 1.45 ± 0.048 mmol TE/g, 0.95 ± 0.04 mmol TE/g, and 0.59 ± 0.023 mmol TE/g, respectively. The highest antimicrobial activity was shown by Staphylococcus aureus in the inhibition zone, with values of 1.40 ± 0.12 mm of OrV and of 10.30 ± 0.04 mm and 11.54 ± 0.10 mm for OrV-AgNPs and OrV-F-AgNPs, respectively. Analysis of phenolic compounds revealed that the highest total amount of the apigenin, 87.78 µg/g, was detected in OrV-F-AgNPs and the lowest amount, 16.56 µg/g, in OrV-AgNPs. Moreover, in OrV-F-AgNPs, the collective amount of proanthocyanidins, hydroxycinnamic, and flavonoids was prominently high in all cases, i.e., 145.00 ± 0.02 mg EE/g DW, 2.86 ± 0.01 mg CAE/g DW, and 0.55 ± 0.01 mg RE/g DW, respectively, as compared to the original extract (102.1 ± 0.03 mg EE/g DW, 2.78 ± 0.02 mg CAE/g DW, and 0.47 ± 0.01 mg RE/g DW, respectively). During the characterization of biosynthesized nanoparticles by scanning electron microscopy (SEM), AgNPs demonstrated a uniform spherical shape with even distribution. The sample’s elemental composition was confirmed with a signal of 3.2 keV using energy-dispersive X-ray spectroscopy (EDS) analysis. Transmission electron microscopy (TEM) analysis showed silver nanoparticles that were round and spherical in shape in both stacked and congested form, with a size range of less than 30 nm. Thus, this green and sustainable synthesis of AgNPs, a blend of Medusomyces gisevii and O. vulgare herbal extract, has adequate potential for increased antimicrobial and antioxidant activity. Full article

The efficiency of CO₂ photoreduction is often limited by the low reactivity of CO₂ molecules and the rapid recombination of photogenerated charge carriers in most of the photocatalysts developed so far. In this study, we report a newly developed p-type Bi₂Te₃/SrTiO₃ (pBT/STO) nanocomposite for efficient CO₂ photoreduction. Upon light irradiation, the thermoelectric pBT with a strong light absorption capacity generates the photothermal effect favoring the activation of CO₂ molecules. Meanwhile, a temperature gradient formed in pBT induces a thermoelectric field via the Seebeck effect, which promotes the charge carriers’ separation/transfer. In addition, the excellent electric conductivity and large work function render pBT an efficient cocatalyst for further improving the charge carriers’ separation/transfer. Owing to the synergistic photothermoelectric (PTE) effect on activation of CO₂ molecules and promotion of charge separation/transfer, the efficiency of CO₂ photoreduction over pBT/STO is significantly enhanced. We achieve the highest CO evolution rate of 28.0 μmol·g_cat⁻¹·h⁻¹ over the optimal pBT(3)/STO, which is 12.8 times that of pure STO. This work suggests that a thermoelectric material and a semiconductor can be incorporated into a nanocomposite system for efficient CO₂ reduction via the synergistic photothermoelectric effect on activating the CO₂ molecules and promoting the charge carriers’ separation/transfer. Full article

The behavior of impurities in cast copper was investigated to simulate production with increased utilization of secondary sources within the framework of a circular economy. The incorporation of impurities, particularly Ni, Sn, and Sb, from recycled Cu may significantly impact the electrorefining process. In this study, commercial anodes were doped with Ni, Sn, and Sb concentrations of 2500–6500 g/t, 300–900 g/t, and 450–950 g/t, respectively. Anode concentrations of Pb and Bi were maintained at 1000 g/t and 350 g/t, respectively. As concentrations were examined at two levels, 860 or 1700 g/t, depending on the commercial anode used to create the doped samples. Electron microscopy with microprobe analysis revealed that the commercial anodes contained three predominant phases: Cu₂O, (Cu,Ag)₂(Se,Te), and a complex oxide phase of Cu, Pb, As, Sb, and/or Bi. Ni, the main impurity, primarily accumulated within the Cu grains, while Sn and Sb tended to form oxidized inclusions. The distribution of Ni in Cu grains was ca. 20% lower in the anodes doped at higher Ni concentrations due to the formation of nickel-bearing inclusions, such as Kupferglimmer and NiO. The doped anodes showed lower quantities of Cu₂O inclusions than the commercial anodes due to the preferential formation of oxides with other impurities, including SnO₂. These findings highlight potential challenges for Cu electrorefining in a circular economy, as Ni, Sb, and Sn may impact the deportment of these impurities to slimes or electrolyte and may cause copper depletion in the refining electrolyte. Full article

Pogo is identified as a deep-seated, intrusion-related gold deposit. Carbonate minerals have a close spatial relationship to hydrothermal gold mineralization in all of its principal ore zones. The carbon and oxygen isotopic ratios of carbonate minerals (siderite, ankerite, and calcite) present within the deposit illustrate the isotopic evolution of the ore-forming fluid. The initial hydrothermal fluid phase is interpreted to be magmatic in origin. The fluid evolution was characterized by a gradual decrease in δ¹⁸O and a slight increase in δ¹³C with decreasing temperature. The dominant carbon-bearing species was CO₂, with methane introduced sporadically. Siderite is associated with early-stage mineralization and occurs with ankerite in main-stage ore assemblages. Calcite is recognized in the later stages of mineralization. Gold in the Pogo deposit occurs as native gold, Au-Bi-Te minerals, inclusions in sulfide minerals, or as “invisible gold”. The latter is found in pyrite, chalcopyrite, arsenopyrite, and quartz, based on ion microprobe analysis. The presence of invisible gold in these minerals has significant metallurgical implications for gold processing at the Pogo mine. Full article

This work examines the solar photocatalytic degradation of the antibiotic sulfamethoxazole (SMX) using molybdenum telluride (MoTe₂)-promoted bismuth oxychloride (BiOCl). Different loadings of molybdenum telluride in the 0–1% range on BiOCl were synthesized and evaluated. Although the presence of MoTe₂ did not alter either the adsorption capacity or the energy gap of BiOCl, the synthesized photocatalyst demonstrated higher photocatalytic activity due to the enhanced separation of photogenerated pairs. The 0.5MoTe₂/BiOCl photocatalyst achieved a kinetic constant nearly 2.8 times higher than that of pure BiOCl, leading to the elimination of 500 μg/L SMX within 90 min. The system’s performance was enhanced under neutral to acidic conditions and lower SMX concentrations. Based on experiments with radical scavengers, photogenerated holes appeared to be the dominant species, with the contribution of reactive species following the order ${\mathrm{h}}^{+}>{\mathrm{O}}_2^{•-}/{\mathrm{e}}^{-}>$¹${\mathrm{O}}_2{>\mathrm{H}\mathrm{O}}^{•}$. Interestingly, in different water matrices, photocatalytic activity was not diminished and even increased by 20%, likely because of the action of photogenerated holes and the selectivity of secondary generated radicals. The photocatalyst retained > 90% of its activity after three sequential experiments. Finally, four transformation products from SMX photodegradation were identified via UHPLC-TOF-MS, and a degradation pathway is proposed. Full article

The work focuses on five epithermal Au-Ag deposits of the Kamchatka volcanogenic belts: Rodnikovoe, Baranyevskoe, Kumroch, Lazurnoe (adularia-sericite type–Ad-Ser) and Maletoyvayam (acid-sulfate type–Ac-Sul). The geochemical characteristics of the deposits were presented based on the results of ICP-OES and fire-assay analysis. The compositions and physicochemical parameters of ore-forming fluids were based on microthermometry, Raman spectroscopy and gas chromatography-mass spectrometry. It was shown that all deposits were comparable in terms of temperatures, salinity and the predominance of H₂O and CO₂ in ore-forming fluids. The deposits were formed at temperatures of 160–308 °C by aqueous fluids with salinities of 0.5–6.8 wt. % (NaCl-eq.). The Maletoyvayam deposit differed from the other ones in significant enrichment in Se, Te, Sb, Bi and As, as well as much higher concentrations of hydrocarbons, nitrogenated and sulfonated compounds (31.4 rel.% in total) in the composition of fluid inclusions. This gave us a reason to assume that organic compounds favourably affected the concentrations of these elements in the mineralising fluid. Kumroch and Lazurnoe were distinguished from Rodnikovoe and Baranyevskoe by high Zn, Pb and Cu contents, where each of them represented a single system combining both Ad-Ser type epithermal gold-silver and copper porphyry mineralisations. The presence of alkanes, esters, ketones, carboxylic acids and aldehydes in different quantities at all deposits were indicators of the combination of biogenic and thermogenic origins of organic compounds. The contents of ore-forming elements in ores were consistent with the specificity of mineral assemblages in the Kamchatka deposits. Full article

Harnessing waste heat from environmental or industrial sources presents a promising approach to eco-friendly and sustainable chemical synthesis. In this study, we introduce a thermoelectrocatalytic (TECatal) system capable of utilizing even small amounts of heat for hydrogen peroxide (H₂O₂) production. We developed a nanohybrid structure, combining carbon nanotubes (CNTs) and Bi₂Te₃ nanoflakes (Bi₂Te₃/CNTs), through a one-pot synthesis method. Bi₂Te₃, as a thermoelectric (TE) material, generates charge carriers under a temperature gradient via the Seebeck effect, enabling them to participate in surface redox reactions. However, the rapid recombination of these charge carriers greatly limits the TECatal activity. In the Bi₂Te₃/CNTs nanohybrid system, the introduction of CNTs substantially enhances the efficiency of H₂O₂ production, as the strong bonding between CNTs and Bi₂Te₃, along with the excellent conductivity of CNTs, facilitates charge carrier separation and transport, as confirmed by TE electrochemical tests. This study underscores the significant potential of thermoelectric nanomaterials for converting waste heat into green chemical synthesis. Full article

Background: Despite the progress achieved regarding survival rates in childhood acute lymphoblastic leukemia (ALL), relapsed or refractory disease still poses a therapeutic challenge. Inotuzumab ozogamicin is a CD22-directed monoclonal antibody conjugated to calicheamicin, which has been approved by the Food and Drug Administration for adults and pediatric patients 1 year and older with relapsed or refractory CD22-positive B-cell precursor acute lymphoblastic leukemia. Case presentation: Herein, we present the case of a 23-month-old girl with high-risk B-ALL who experienced very early isolated medullary relapse; following the failure of conventional chemotherapy according to the ALL-IC REL 2016 protocol, she went on to receive the bispecific T-cell engager (BiTE) blinatumomab and subsequently, due to refractory disease, the combination of fludarabine, cytarabine, and the proteasome inhibitor bortezomib without achieving remission. Given the high CD22 expression by the lymphoblasts, off-label use of inotuzumab ozogamicin (InO) was chosen and administrated in a 28-day cycle as a salvage treatment. The minimal residual disease (MRD) was 0.08% on day 28, and InO was continued, thus achieving MRD negativity; the patient successfully underwent an allogeneic stem cell transplantation from a matched family donor. Conclusions: Our case highlights the efficacy and safety of InO as a salvage treatment in the setting of relapsed B-ALL refractory not only to conventional chemotherapy but also to novel treatments, such as blinatumomab and bortezomib. Full article

Chrysanthemum morifolium cv. Fubaiju (CMF) is regarded as one of the three most renowned varieties of white Chrysanthemum in China, and different extraction methods have significant effects on its composition and activities. Therefore, six extractions were used in this study to assess the effects on extracts. The basic chemical composition showed that hot water extract (Hw) had the highest total phenolic content, alkali water immersion-assisted hot water extract (Al) had the highest content of protein, and enzyme-assisted hot water extract (Enz) had the highest content of carbohydrate. The UPLC-Q-Exactive-MS results evinced the presence of 19 small-molecule compounds, including chlorogenic acid, caffeic acid, tuberonic acid glucoside, luteolin-7-O-rutinoside, and other substances. In addition, the antioxidant test found that the Hw exhibited the best 1,1-diphenyl-2-picrylhydrazyl (DPPH) (82.05 ± 1.59 mM TE/mg) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (61.91 ± 0.27 mM TE/mg) scavenging ability. The anti-glycation test demonstrated that Enz possessed the most pronounced inhibitory effect on glycation products, including fructosamine and advanced glycation end products (AGEs). Additionally, the Enz also exhibited the most significant inhibitory effect on the protein oxidation product N’-formylkynurenine. The correlation analysis revealed that there was a close relationship between antioxidant properties and glycation resistance of extracts, and tuberonic acid glucoside, 1,3-di-O-caffeoylquinic acid, 1,4-Dicaffeoylquinic acid, quercetin-7-O-β-D-glucopyranoside, and isochlorogenic acid B were key small molecule components that affected activities. In summary, the extracts of CMF can be regarded as an excellent antioxidant and anti-glycosylation agent. Full article

Quercus infectoria Olivier (Fagaceae) nutgall, a traditional Asian medicine, is renowned for its efficacy in treating wounds and skin disorders. Although the gall extract has shown promising results in accelerating wound healing in diabetic animal models, its mechanisms, particularly the effects on redox balance, remain poorly understood. This study aims to investigate the effects and mechanisms of Q. infectoria gall ethanolic extract (QIG) on wound healing in fibroblasts, with a specific emphasis on its modulation of oxidative stress. Hydrogen peroxide (H₂O₂)-treated L929 cells were used as an in vitro model of oxidation-damaged fibroblasts. QIG exhibited potent antioxidant activity with 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric reducing antioxidant power (FRAP) assay values of 305.43 ± 7.48, 508.94 ± 15.12, and 442.08 ± 9.41 µM Trolox equivalents (TE)/µg, respectively. Elevated H₂O₂ levels significantly reduced L929 cell viability, with a 50% lethal concentration of 1.03 mM. QIG mitigated H₂O₂-induced cytotoxicity in a dose-dependent manner, showing protective effects in pre-, post-, and co-treatment scenarios. QIG significantly reduced H₂O₂-induced intracellular reactive oxygen species production and inflammation-related gene expression (p < 0.05). Additionally, at 25 µg/mL, QIG remarkably improved wound closure in H₂O₂-treated L929 cells by approximately 9.4 times compared with the H₂O₂ treatment alone (p < 0.05). These findings suggest QIG has potential therapeutic applications in wound healing, mediated through the regulation of oxidative stress and inflammatory response. Full article

Non-thermal plasma as an emergent technology has received considerable attention for its wide range of applications in agriculture, material synthesis, and the biomedical field due to its low cost and portability. It has promising antimicrobial properties, making it a powerful tool for bacterial decontamination. However, traditional techniques for producing non-thermal plasma frequently rely on radiofrequency (RF) devices, despite their effectiveness, are intricate and expensive. This study focuses on generating Ar-O₂ capacitively coupled plasma under vacuum conditions, utilizing a low-frequency alternating current (AC) power supply, to evaluate the system’s antimicrobial efficacy. A single Langmuir probe diagnostic was used to assess the key plasma parameters such as electron density (n_e), electron temperature (T_e), and electron energy distribution function (EEDF). Experimental results showed that n_e increases (7 × 10¹⁵ m⁻³ to 1.5 × 10¹⁶ m⁻³) with a rise in pressure and AC power. Similarly, the EEDF modified into a bi-Maxwellian distribution with an increase in AC power, showing a higher population of low-energy electrons at higher power. Finally, the generated plasma was tested for antimicrobial treatment of Xanthomonas campestris pv. Vesicatoria. It is noted that the plasma generated by the AC power supply, at a pressure of 0.5 mbar and power of 400 W for 180 s, has 75% killing efficiency. This promising result highlights the capability of the suggested approach, which may be a budget-friendly and effective technique for eliminating microbes with promising applications in agriculture, biomedicine, and food processing. Full article

This brief review covers the thermoelectric properties of one-dimensional materials, such as nanowires and nanotubes. The highly localised peaks of the electronic density of states near the Fermi levels of these nanostructured materials improve the Seebeck coefficient. Moreover, quantum confinement leads to discrete energy levels and a modified density of states, potentially enhancing electrical conductivity. These electronic effects, coupled with the dominance of Umklapp phonon scattering, which reduces thermal conductivity in one-dimensional materials, can achieve unprecedented thermoelectric efficiency not seen in two-dimensional or bulk materials. Notable advancements include carbon and silicon nanotubes and Bi₃Te₂, Bi, ZnO, SiC, and Si_1−xGe_x nanowires with significantly reduced thermal conductivity and increased ZT. In all these nanowires and nanotubes, efficiency is explored as a function of the diameter. Among these nanomaterials, carbon nanotubes offer mechanical flexibility and improved thermoelectric performance. Although carbon nanotubes theoretically have high thermal conductivity, the improvement of their Seebeck coefficient due to their low-dimensional structure can compensate for it. Regarding flexibility, economic criteria, ease of fabrication, and weight, carbon nanotubes could be a promising candidate for thermoelectric power generation. Full article

TeO₂-Bi₂O₃-B₂O₃-ZnO laser glasses doped with Er³⁺ were synthesized through an optimized melt-quenching method. The absorption spectra at 808 nm LD pumping were studied. Various spectral tests and data analyses indicate that the maximum fluorescence emission intensity can be obtained when the Er³⁺ doping concentration reaches 2%. In this case, the emission cross-section can reach up to 9.12 × 10⁻²¹ cm² and the gain coefficient at 1.55 μm is 6.17 cm⁻¹. Simultaneously, the sample has a lower phonon energy in the high-frequency band at 1077 cm⁻¹, which reduces the probability of non-radiative relaxation. The calculated energy transfer coefficient C_D-A is 13.8 × 10⁻⁴⁰ cm⁶/s, reflecting the high cross-relaxation probability of Er³⁺ in the sample, which promotes the luminescence of 1.55 μm and favors the emission in the near-infrared region. The comprehensive results demonstrate that the prepared Er³⁺-doped bismuth telluride laser glass can be used as a promising and high-quality gain material for near-infrared lasers. Full article

This research employs the COMSOL Multiphysics software (COMSOL 6.2) to conduct rigorous simulations and assess the performance of a thermoelectric module (TEM) meticulously crafted with alumina (Al₂O₃), copper (Cu), and Bi₂Te_2.70Se_0.30 thermoelectric (TE) materials. The specific focus is on evaluating diverse aspects of the Bi₂Te_2.70Se_0.30 thermoelectric generator (TEG). The TEM design incorporates Bi₂Te_2.70Se_0.30 for TE legs of the p- and n-type positioned among the Cu layers, Cu as the electrical conductor, and Al₂O₃ serving as an electrical insulator between the top and bottom layers. A thorough investigation is conducted into critical parameters within the TEM, which include arc length, electric potential, normalized current density, temperature gradient, total heat source, and total net energy rate. The geometric configuration of the square-shaped Bi₂Te_2.70Se_0.30 TEM, measuring 1 mm × 1 mm × 2.5 mm with a 0.25 mm Al₂O₃ thickness and a 0.125 mm Cu thickness, is scrutinized. This study delves into the transport phenomena of TE devices, exploring the impacts of the Seebeck coefficient (S), thermal conductivity (k), and electrical conductivity (σ) on the temperature differential across the leg geometry. Modeling studies underscore the substantial influence of S = ±2.41 × 10⁻³ V/K, revealing improved thermal conductivity and decreased electrical conductivity at lower temperatures. The findings highlight the Bi₂Te_2.70Se_0.30 TEM’s high potential for TEG applications, offering valuable insights into design and performance considerations crucial for advancing TE technology. Full article