Search Results (247)

The lower melt strength of biodegradable materials in comparison to low density polyethylenes raises serious issues regarding their processability via blown film molding. Thus, reliable rheological characterization is a viable option for assessing their efficient flow performance. The blends of poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT) modified with four chain-extending cross-linkers (CECLs) undergo shearing during extrusion and are subjected to extensional deformation during the subsequent film blowing. The shear viscosity data obtained with a capillary rheometer corresponded well to the molecular weights obtained by gel permeation chromatography, while an evaluation of elongational viscosity using a Sentmanat Extensional Rheometer failed due to sample sagging during the process of temperature setting and an unacceptable deviation from the theoretically supposed exponential decrease of sample cross-sections. Therefore, the response of the PBAT/PLA blends to elongation was determined via changes in the duration of time intervals corresponding to the rupture of elongated samples. An increased consistency of the PBAT/PLA blends with CECL, as previously indicated by dynamic mechanical analysis, differential scanning calorimetry, and scanning electron microscopy, was evaluated in this way. Full article

Shape memory alloys (SMAs) are known for their exceptional mechanical properties, particularly their superior wear resistance compared to conventional alloys with similar surface hardness. Rare earth oxides are often used as additives to further improve these characteristics. This study investigates the effects of different CeO₂ (cerium dioxide) concentrations (0.01 wt.%, 0.1 wt.%, 0.5 wt.%, and 1.0 wt.%) on the properties of CuAlMnFe alloys produced via powder metallurgy (PM). Various analyses were performed, including scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray diffraction (XRD), as well as hardness, wear, and corrosion tests. The increase in wear rate is closely related to the formation of precipitates from CeO₂ addition. Improvements in wear resistance and hardness are attributed to the effects of grain refinement and solid solution strengthening due to CeO₂. Specifically, the wear rate increased from 1.5 × 10⁻³ mm³/(Nm) to 3.4 × 10⁻³ mm³/(Nm) with higher CeO₂ content. Additionally, the friction coefficient of the CuAlMnFe alloy was reduced with CeO₂ addition, indicating enhanced frictional properties. The optimal CeO₂ concentration of 0.5% was found to improve grain uniformity, resulting in better wear resistance. Incorporating CeO₂ particles into CuAlMnFe alloy enhances hardness and reduces wear rate when used in appropriate amounts. Additionally, it exhibits superior corrosion resistance, as evidenced by a positive shift in corrosion potential in Tafel measurements in solutions and a decrease in corrosion current density. The C0.5 specimen showed the highest corrosion potential (E_corr, −588 V) and the lowest corrosion current density (i_corr, 6.17 μA/cm²) during electrochemical corrosion in 3.5 wt.% NaCl solution. Full article

TiAl alloy offers advantages including low density, high specific strength and stiffness, and excellent high-temperature creep resistance. It is widely used in the aerospace, automotive, and chemical sectors, as well as in other fields. However, at temperatures of 800 °C and above, it forms a porous oxide film predominantly composed of TiO₂, which fails to provide adequate protection. Applying high-temperature protective coatings is therefore essential. Oxides demonstrating protective efficacy at elevated temperatures include Al₂O₃, Cr₂O₃, and SiO₂. The Pilling–Bedworth Ratio (PBR)—defined as the ratio of the volume of the oxide formed to the volume of the metal consumed—serves as a critical criterion for assessing oxide film integrity. A PBR value greater than 1 but less than 2 indicates superior film integrity and enhanced oxidation resistance. Among common oxides, Al₂O₃ exhibits a PBR value within this optimal range (1−2), rendering aluminum-based compound coatings the most extensively utilized. Aluminum coatings can be applied via methods such as pack cementation, thermal spraying, and hot-dip aluminizing. Pack cementation, being the simplest to operate, is widely employed. In this study, a powder mixture with the composition Al:Al₂O₃:NH₄Cl:CeO₂ = 30:66:3:1 was used to aluminize γ-TiAl intermetallic compound specimens via pack cementation at 600 °C for 5 h. Subsequent isothermal oxidation at 900 °C for 20 h yielded an oxidation kinetic curve adhering to the parabolic rate law. This treatment significantly enhanced the high-temperature oxidation resistance of the γ-TiAl intermetallic compound, thereby broadening its potential application scenarios. Full article

Contact electrification (CE), or triboelectrification, is an electron transfer phenomenon occurring at the interface between dissimilar materials due to differences in polarity, holding significant research value in tribology. The microscopic mechanisms of CE remain unclear due to the complex coupling of multiple physical processes. Recently, with the rise of triboelectric nanogenerator (TENG) technology, solid–liquid contact electrification has demonstrated vast application potential, sparking considerable interest in its underlying mechanisms. Emerging experimental evidence indicates that at water–polymer CE interfaces, the process involves not only traditional ion adsorption but also electron transfer. Halogen-containing functional groups in the solid material significantly enhance the CE effect. To elucidate the microscopic mechanism of water–polymer CE, this study employed first-principles density functional theory (DFT) calculations, simulating the interfacial electrification process using unit cell models of water contacting polymers. We systematically and quantitatively investigated the charge transfer characteristics at interfaces between water and three representative polymers with similar backbones but different halogen-functionalized (F, Cl) side chains: fluorinated ethylene propylene (FEP), polyvinyl chloride (PVC), and polytetrafluoroethylene (PTFE), focusing on evaluating halogen’s influence and mechanism on interfacial electron transfer. The results reveal that electron transfer is primarily governed by the energy levels of the polymer’s lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO). Halogen functional groups modulate the material’s electron-donating/accepting capabilities by altering these frontier orbital energy levels. Consequently, we propose that the critical strategy for polymer chemical modification resides in lowering the LUMO energy level of electron-accepting materials. This study provides a novel theoretical insight into the charge transfer mechanism at solid–liquid interfaces, offers guidance for designing high-performance TENG interfacial materials, and holds significant importance for both the fundamental theory and the development of advanced energy devices. Full article

The microscale solid and pore structures of waste is crucial for the bio-hydro-mechanical behaviors of landfilled municipal solid waste (MSW). The quantitative analysis of the structural characteristics of MSW is still limited. In this study, borehole MSW samples at different depths (i.e., 0 m, 2.5 m, 5 m, 7.5 m, 10 m, and 12.5 m) were drilled from a landfill. The waste composition and basic physical properties of these samples were tested in laboratory. Solid and pore structural characteristics were studied through computed tomography (CT) analysis. The results indicate that the ratio of cellulose content to lignin content (i.e., C/L) decreased from 0.85 to 0.47 with increasing depth. For solid particles, two-dimensional (2D) particles constituted the greatest fraction (60.22~72.16%), which showed a decrease with increasing depth. The deeper sample tended to have more fine particles. For pores, the void ratio decreased from 1.68 to 1.10 with increasing depth, with more small pore channels. Meanwhile, the average pore diameter coefficient (λ) decreased from 0.209 to 0.190, the pore angle (θ_e) decreased from 29.6° to 17.8°, the tortuosity (τ) increased from 1.129 to 1.184, and the connectivity (c_e) decreased from 12.0 to 4.1. These quantitative findings can further the understanding of fluid flow behaviors in landfilled waste. Full article

Electrochemical formation of ceria (mixed Ce₂O₃ and CeO₂) coatings on different types of screen-printed carbon electrodes (SPCEs) (based on graphite (C110), carbon nanotubes (CNT), single-walled carbon nanotubes (SWCNT), carbon nanofibers (CNF), and mesoporous carbon (MC)) were studied. Their potential applications as catalysts for various redox reactions and electrochemical sensors were investigated. The ceria oxide layers were electrodeposited on SPCEs at various current densities and deposition time. The morphology, structure, and chemical composition in the bulk of the ceria layers were studied by SEM and EDS methods. XRD was used to identify the formed phases. The concentration, chemical composition and chemical state of the elements on the surface of studied samples were characterized by XPS. It was established that the increase of the concentration of CeCl₃ in the solution and the cathode current density strongly affected the surface structure and concentration (relation between Ce³⁺ and Ce⁴⁺, respectively) in the formed ceria layers. At low concentration of CeCl₃ (0.1M) and low values of cathode current density (0.5 mA·cm⁻²), porous samples were obtained, while with their increase, the ceria coatings grew denser. Full article

The influence of multiwall carbon nanotube (MWCNT) reinforcements on electrochemical corrosion investigations at varying NaCl concentrations (0.4 M, 0.6 M, 0.8 M, 1 M) of Mg-Zn-Ce nanocomposites is studied in this work. The Mg-Zn-Ce/MWCNT nanocomposites were developed by using an ultrasonication-assisted hybrid stir–squeeze (UHSS) casting method with different MWCNT concentrations (0, 0.4, 0.8, 1.2 wt.%) in a Mg-Zn-Ce magnesium alloy matrix. The microstructural characterizations shown using X-ray diffraction revealed the presence of secondary phases (MgZn₂, Mg₁₂Ce), T-phase (Mg₇Zn₃RE), α-Mg, and MWCNT peaks. Optical microscopy results showed grain refinement in the case of nanocomposites. Transmission electron microscope studies revealed well-dispersed MWCNT, indicating the good selection of processing parameters. The uniform dispersion of MWCNTs was achieved due to a hybrid stirring mechanism along with transient cavitation, ultrasonic streaming, and squeeze effect. The higher E_corr value of −1.39 V, lower I_corr value (5.81 µA/cm²), and lower corrosion rate of 0.1 mm/Yr (↑77%) were obtained by 0.8% nanocomposite at 0.4 M NaCl concentration, when compared to the monolithic alloy. The Mg(OH)₂ passive film formation on 0.8 wt.% nanocomposite was denser, attributed to the refined grains. At higher NaCl concentration, the one-dimensional morphological advantage of MWCNT helped to act as a barrier for further Mg exposure to excessive Cl⁻ attack, which reduced the formation of MgCl₂. Therefore, the UHSS-casted Mg-Zn-Ce/MWCNT nanocomposites present a good potential as sacrificial anodes for use in a wide range of industrial applications. Full article

Objective: This study aims to evaluate the stress distribution on endodontically treated anterior teeth restored using different restorative materials and different post lengths versus endocrowns employing finite element analysis (FEA). Methods: An extracted human central incisor tooth with a fully formed apex was scanned using high-resolution cone beam computed tomography (CBCT) to generate 3D finite element models. Six models of restorations of badly destructed central incisor were grouped according to the type of ceramic material and post length versus endocrown restorations. Group V-L: Vita Enamic, long post (10 mm intra-radicular), Group C-L: Celtra Duo, long post (10 mm intra-radicular), Group V-Sh: Vita Enamic, short post (3 mm intra-radicular), Group C-Sh: Celtra Duo, short post (3 mm intra-radicular), Group V-E: Vita Enamic endocrown (3 mm intra-radicular), and Group C-E: Celtra Duo endocrown (3 mm intra-radicular). A static load of 200 N was applied to the palatal surface at a 45 degree angle to the tooth’s long axis. The maximum equivalent von Mises stress and maximum principal stress were analyzed at four locations: the finish line, coronal third of the root (12 mm from the apex), middle third of the root (8 mm from the apex), and apical third of the root (4 mm from the apex). Results: Group C-L exhibited the highest maximum VM stress and PS at the finish line, in addition to the highest maximum VM stress and PS at the root apical third, while group C-Sh reported the least maximum VM stress at the root apical third among the groups. All Celtra Duo groups reported higher maximum VM stress than the corresponding groups of Vita Enamic at the finish line and root coronal thirds. However, at the root middle and apical thirds, both materials recorded similar stresses. Conclusions: Short posts and Vita Enamic endocrowns showed minimal stress, especially at the finish line, while long posts increased stress and fracture risk. The findings support conservative restorations without posts, although clinical validation is needed to confirm their long-term effectiveness and safety. Full article

The novel hydro-electro hybrid priming (HEHP) technique, which synergistically combines controlled hydration and electrostatic field application, represents an innovative chemical-free approach to improve seed germination synchrony. However, the regulatory mechanism of HEHP on cell wall remodeling during post-imbibition remains unclear. Here, we demonstrate that HEHP accelerates carrot (Daucus carota L.) seed germination by synchronizing cell wall hydrolysis and synthesis pathways. Comparative transcriptomics revealed 4591 differentially expressed genes (DEGs) between HEHP-treated and untreated seeds, with significant enrichment in cell wall organization (GO terms) and phenylpropanoid biosynthesis (KEGG pathway). HEHP significantly induced the expression of expansin (EXP), hydrolases (xyloglucan endotransglucosylase (XET), pectinesterase (PE), and phenylalanine ammonia lyase (PAE)), and synthases (cellulose synthase (CesA)), reducing endosperm rupture force considerably at S20 compared to hydropriming (HYD). Enzymatic assays confirmed earlier activity peaks for XET and PE in HEHP, correlating with the sustained expression of key genes. Notably, HEHP pre-activated germination-related metabolism, evidenced by fewer post-imbibition DEGs, and synchronized lignin deposition via transient phenylalanine ammonia lyase (PAL) and 4-coumarate/CoA ligase (4CL) activation. These synergies enabled faster radicle emergence than HYD. Our findings reveal that HEHP optimizes cell wall loosening–reinforcement dynamics through transcriptional priming, offering a tailored solution for mechanized sowing in Apiaceae crops. Full article

The Shuixie Cu–Co polymetallic orefield, located in western Yunnan Province (southeastern margin of the Qinghai–Tibet Plateau), is renowned for its Cu–Co mineralization. A recent resource reassessment identified Sb–Au and Cu–Co–Bi (Sb–Au) orebodies as genetically associated with primary Cu–Co mineralization. The mineralization characteristics and microscopic observations indicate that gold mineralization in the Sb–Au orebodies follow a pulsating fluid injection model. The model includes four pulses: (1) euhedral gold-poor pyrite (PyI₁) precipitation; (2) margin-parallel growth of gold-rich pyrite (PyI₂) on PyI₁; (3) continued growth of gold-rich pyrite (PyI₃) along PyI₂; and (4) outermost concentric gold-rich pyrite (PyI₄) formation. This study examined gold-bearing pyrite in orebodies and host rocks. In situ laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) analysis of pyrite and inductively coupled plasma mass spectrometry (ICP–MS) whole-rock trace element analysis were conducted to track the ore-forming fluid evolution. Compared with CI chondrite, pyrites from all pulses were enriched in LREEs over HREEs. The pyrite REE distribution curves exhibited right-skewed patterns, reflecting LREE enrichment. The Hf/Sm, Nb/La, and Th/La ratios were generally below 1, indicating high-field-strength element depletion. These results suggest a Cl-rich, F-poor ore-forming fluid. The pyrite trace elements showed enrichment in the chalcophile elements (e.g., Cu and Pb) and exceptionally high Bi levels compared with the continental crust. The chalcophile elements (e.g., Zn and Cd) were depleted, whereas iron-group elements (e.g., Co) were enriched and Ni was depleted. The pyrite δCe values (0.87–1.28, mean = 1.01) showed weak anomalies, indicating a reducing ore-forming environment. The δEu values of pyrite during pulses 1 to 4 ranged widely, from 0.2–3.01 (mean of 1.17), 0.27–1.39 (0.6), and 0.41–1.40 (0.96) to 0.4–1.36 (0.84), respectively, suggesting an initial temperature decline and subsequent increase in the ore-forming fluid. Significant variations were found in the Y/Ho, Zr/Hf, and Nb/Ta ratios across pulses, indicating the potential involvement of high-temperature hydrothermal fluids or late-stage alteration during ore formation. The Y/Ho ratio of pyrite overlapped most closely with that of the continental crust of China, indicating a close relationship between the ore-forming fluids and the crust. Full article

This study provides insights into the stabilization effects of certain oxides (CeO₂, Cr₂O₃, Cd₂O₃, In₂O₃, MnO₂, MgO, Nd₂O₃, and Pr₂O₃) in styrene–isoprene–styrene triblock copolymers with respect to neat materials. This study was performed via chemiluminescence (CL), which allowed for the determination of the main parameters characterizing the interphase coexistence: the oxidation induction times, oxidation rates, and onset oxidation temperatures. The improvement in the thermal performances of the pristine and γ-ray-processed samples at a moderate dose was highlighted differently due to the electronic interactions on the particle surface. While the non-isothermal CL measurements pointed to a weaker evolution of oxidation in the studied composites at a higher temperature range over 160 °C, the isothermal CL determinations revealed a delayed start of oxidation, slower oxidation rates, and greater activation energies in the nanocomposite aging patterns. The different individual behaviors of the investigated formulations were ascribed to the dissimilar electronic interactions between the particles and the surrounding matrix, where the oxidation initiators were formed by the molecular fragmentation of the polymer macromolecules. The kinetic features illustrate the influence of the peculiarities due to the electronic interactions. The higher resistance shown by the irradiated samples compared with the non-processed compositions demonstrates the stabilization efficiency of the fillers studied. Full article

A new type of CeO₂-modified AgCl catalyst (CeO₂/AgCl) was prepared by a one-step method, which efficiently inhibits the recombination of photogenerated carriers. During the visible-light degradation process, this catalyst exhibited excellent and stable performance. It could not only effectively degrade rhodamine B (RhB), methyl orange (MO) and crystal violet (CV) but also maintain excellent activity under different environmental conditions. In the RhB degradation experiment in particular, the CeO₂/AgCl-30 composite with the optimal proportion had a degradation rate 5.43 times that of pure AgCl in the seawater system and 9.17 times that of pure AgCl in the deionized water condition, while also showing excellent stability. Through characterization tests such as XRD, XPS and ESR, its crystal structure, elemental composition and so on were analyzed. Based on the characterization results, the CeO₂/AgCl composite showed a relatively wide light absorption range and a relatively high photo-induced charge separation efficiency. Meanwhile, it was inferred that the main active species in the reaction process were ·O₂⁻ and ·OH. Finally, based on its electronic band structure, an S-scheme heterojunction structure was proposed. Full article

In this paper, we synthesized a chain-like organic cation structure directing agent L·Cl₂ by reacting triethylenediamine with 1,2-bis(2-chloroethoxy)ethane. We then used a room temperature volatilization method to react L·Cl₂ with inorganic metal salts to synthesize five organic–inorganic hybrid supramolecules: {[L][HgI₄]} (1), {[L][CdI₄]} (2), {[(L)(Cu₂I₃)]·[CuI₂]CH₃CN}_n (3) {[L][CoCl₃]₂} (4), and {[L][Ce(NO₃)₅·(H₂O)₂]} (5) (L=1,1′-((ethane-1,2-diylbis(oxy))bis(ethane-2,1-diyl))bis(1,4-diazabicyclo [2.2.2]octan-1-ium) chloride). The compounds were characterized by X-ray diffraction, infrared spectroscopy, elemental analysis, and thermogravimetric analysis. Compounds 1, 2, and 5 are mononuclear anion compounds, while compound 3 is a 1D chain, and 4 is a binuclear anion compound. The results showed that 10 mg of compound 3 achieved 92.22% of tetracycline degradation efficiency in the initial TC solution pH = 7. The optimal conditions such as solution pH, catalyst dosage, and solution temperature for the photocatalytic degradation of TC wastewater by compound 3 were explored. Moreover, the photocatalytic degradation efficiency of compound 3 was above 86% each time after four cycles, indicating a good recyclability. The mechanism of photocatalytic degradation was also discussed. Full article

Carbon emissions (CE) from expanding construction land (CL), a vital territory for human production and habitation, have contributed to climate change worldwide. The Yellow River Basin (YRB), an essential economic region and energy supply base in China, is experiencing rapid urbanization, and the contradiction between economic development and ecological protection is increasingly acute. Consequently, a thorough examination of the spatial and temporal change features of carbon emissions from construction land (CECL) and its decoupling from economic growth (EG) is crucial for the maintaining development of the region. This study adopts the IPCC carbon emission coefficient approach for measuring the CECL in the YRB from 2010 to 2021. The temporal and spatial variation features of CECL in the YRB were revealed using ArcGIS software and the standard deviation ellipse (SDE) model. The decoupling effect between CECL and EG was analyzed using the Tapio decoupling model and innovatively combined with the Logarithmic Mean Divisia Index (LMDI) method to explore the influence of five main drivers on the decoupling effect. This study found that: (1) The CECL rose from 2.463 billion tons in 2010 to 3.329 billion tons in 2021. The spatial layout of CECL is “high in the east and low in the west”. (2) The SDE of CECL is distributed in the direction of “northeast to southwest”, and the gravity center’s moving path is “northwest to northeast to northwest”; (3) weak decoupling (WD) is the main decoupling state between CECL and EG; (4) the economic output effect and the construction land (CL) scale effect are the two main factors inhibiting the decoupling of CECL, while the energy intensity effect, the population density effect, and the energy structure effect are the main elements motivating the decoupling of CECL. This study provides specific references and bases for the YRB in China and other countries and regions with similar levels of development in promoting green and ecologically friendly initiatives and achieving low-carbon utilization of regional land and sustainable development. Full article

In production and transportation systems of the oil industry, brine solutions contain high concentrations of chloride and dissolved CO₂, which is a very corrosive medium to which carbon steel is exposed. Therefore, finding new effective and environmentally friendly corrosion inhibitors is of great importance. The effect of CeCl₃ (in concentrations from 5 mg dm⁻³ to 20 mg dm⁻³) and oleic acid imidazoline (IOA) (in concentrations from 5 mg dm⁻³ to 20 mg dm⁻³) separately and their mixtures (in concentrations from 5 mg dm⁻³ to 15 mg dm⁻³ of CeCl₃ and from 5 mg dm⁻³ to 20 mg dm⁻³ of IOA) as corrosion inhibitors of AISI 1018 carbon steel corrosion in simulated brine solution saturated with CO₂ at 60 °C were examined by means of weight-loss testing, electrochemical measurements (polarization resistance, linear polarization with Tafel extrapolation, electrochemical impedance spectroscopy) and surface analyses (scanning electron microscopy with energy-dispersive X-ray spectroscopy analyses, Raman spectroscopy and X-ray diffraction). All test methods showed a higher efficiency of compounds′ mixtures (from 62.77% to 97.94%) and a higher degree of corrosion protection compared to the action of individual compounds (efficiency from 3.43% to 94.61% for IOA and from 57.58% to 96.27% for CeCl₃). Imidazoline, a common corrosion inhibitor in CO₂-saturated systems, most likely forms a surface film with voids via its adsorption on steel surface, while cerium carbonate tends to fill these voids by creating a more compact film. In this way, a denser and thicker surface film is formed. Full article