Ti Content Research Articles

Unveiling the Effect of Ti Micro-Alloying on the Microstructure and Corrosion Resistance of the GH3536 Alloy Processed by Laser Metal Deposition in a Simulated Environment for PEMFCs

This article addresses the knowledge gap regarding the effect of Ti addition on the microstructure and corrosion behavior of the LMD-processed GH3536 alloy in a simulated solution of proton exchange membrane fuel cells (PEMFCs). The microstructural evolution, corrosion resistance, and passive film characteristics of LMD-processed GH3536 alloy with varying Ti contents were characterized through a variety of techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), X-ray photoelectron spectroscopy (XPS), and a series of electrochemical measurements. The results indicate that the corrosion resistance of the LMD-processed GH3536 alloy significantly improves with increasing Ti content. However, when the Ti content exceeds 0.2 wt.%, the beneficial effect on corrosion resistance is weakened. Two primary mechanisms explain the enhanced corrosion resistance, involving the heterogeneous nucleation of Ti-modified Al2O3 and Ti solute segregation, which promotes grain refinement. In addition, grain refinement can provide more active sites for the formation of compact passive films, thereby improving corrosion resistance of the GH3536 alloy.

Significant Improvement in Mild Steel Mechanical Properties with Cu-Fe-Ti Alloy Coatings

This research examines the mechanical properties of mild steel using the electrodeposition of ternary Cu-Fe-Ti alloys with varying Ti compositions at room temperature. The coating process maintained constant pH, current density, deposition time, and temperature. X-ray diffraction analysis revealed single-phase compositions with a face-centered cubic (fcc) structure for all electrodeposited samples. The crystallite sizes ranged from 14-17 nm. The lattice parameters of the Cu-Fe-Ti alloys strongly depended on the Ti concentration. Scanning electron microscopy images showed smoother surfaces with increasing Ti content. Energy-dispersive X-ray spectroscopy confirmed the presence of Cu, Fe, and Ti in the coatings. The Vicker hardness increased from 255 HV to 444 HV. With more Ti in solution, the Cu-Fe-Ti alloy coating thickness on mild steel decreased from 63 μm to 25 μm, and the surfaces became smoother. Thus, the improved mechanical properties correlate with Ti concentration, lattice parameter, crystallite size, and coating thickness. Enhanced mechanical properties of mild steel with Cu-Fe-Ti alloy coatings offer potential for improved durability and performance in radiation therapy equipment and medical imaging devices.

Lattice energy transfer from homo-crystalline substitution for enhanced piezo-photocatalytic CO2 conversion

The rapid recombination of carriers and large activation energy of CO2 compromise the efficiency of CO2 photoreduction. Herein, SrTiO3 (STO) with different molar ratios of La3+ and Al3+ double-site homo-crystalline substitution is prepared by a ball-milling molten salt method. The concentration of Ti3+ and excess oxygen vacancies decrease to improve the catalytic activity. Meanwhile, the double sites act as electron transfer platforms for easy electron transfer from the bulk phase to the surface to foster CO2 photoreduction. Not only that, the energy transfer due to doping-induced lattice distortion can potentially enhance the photocatalytic activity. A piezoelectrically polarized electric field is introduced to further expedite charge transport. As a result, the activity of La, Al-STO piezo-photocatalytic CO2 reduction is improved to 39.17 µmol g-1h−1, which is more than seven times better than that of the pure STO. Furthermore, CO2 adsorbs spontaneously on the catalysts because the thermodynamic energy barrier decreases due to the piezoelectric force, which is verified by density-functional theory calculation. This study reveals the great potential of double-site homo-crystalline substitution of STO pertaining to the charge transport kinetics and thermodynamics of the catalytic reaction in the piezo-photocatalytic CO2 process.

Effect of Ti addition on the microstructure and corrosion behavior of laser cladding AlCoCrFeNi high-entropy alloy coatings

AlCoCrFeNi high-entropy alloys (HEAs) has higher strength and wear resistance but poorer corrosion resistance. In the present investigation, the AlCoCrFeNi HEAs containing titanium(Ti) were fabricated via laser cladding to enhance the corrosion resistance properties of the coating and the influence of the Ti content on the microstructure of the coatings was investigated. The results show that the microstructure of the coating changed from a single BCC phase to a BCC+B2 phase with the addition of Ti. The Laves phases appeared within the coating when the Ti content was beyond 0.5 mol ratio. As an excellent corrosion-resistant element, Ti promoted the formation of a passive film and enhanced the corrosion resistance of the HEAs coating. The corrosion resistance of the coating first increased and then decreased with the addition of Ti, and the AlCoCrFeNiTi0.5 coating exhibited optimal corrosion resistance.

Mineralogical Characteristics and Purification Experiments of Quartz from a Pegmatite: A Case Study in the Lushi Region of the Qinling Orogenic Belt, Central China

This study uses a sample of pegmatite (LS-1) from the Longquanping deposit in Lushi County, Henan Province, to evaluate its potential as a valuable source of HPQ. This investigation uses various analytical techniques to assess the quality of quartz and its suitability for industrial applications. The methods used in this study include optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, X-ray fluorescence spectrometry (XRF), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and inductively coupled plasma mass spectrometry (ICP-MS) to analyze the petrographic, mineralogical, and trace element characteristics of quartz before and after purification and comprehensively evaluate the potential of quartz in these rocks as an HPQ raw material ore. The optical and scanning electron microscopic observations reveal several impurities and associated minerals in quartz, including feldspar, biotite, magnetite, sphene, and large number of fluid inclusions composed of both gas and liquid phases. The content of trace element in raw quartz ore in the LS-1 sample as determined by LA-ICP-MS analysis ranges from 41.61 to 256.13 ppm, with the main impurity elements being Al, Ti, Li, Na, K, and Ca. After purification, the SiO2 contents and total trace elements contents of the LS-1 refined quartz sand was 99.997 wt.% and 29.29 ppm, respectively, with Al (13.29 ppm), Ti (4.20 ppm), Li (1.15 ppm), and Na (10.32 ppm). The major trace element contents of Al and Ti in the quartz concentrates were lower than the upper limit of the HPQ standard and thus belonged to the high-end products (4N8). Results of this study show that quartz from a pegmatite in the Lushi region has the potential to be purified HPQ. This study underscores the importance of thorough mineralogical and elemental analyses in assessing the suitability of quartz raw material deposits for HPQ production.

Metal concentration in bottom sediments for a tropical river, geological or anthropogenic source?

The study analyzes data from a survey of metal concentrations in bottom sediments from both margins (left and right) of the lower main channel of the Orinoco River. This study aims to analyze metal concentrations in the bottom sediments of the lower Orinoco River with different geological settings and anthropological sources. El Almacen (ALM), Las Galderas (G), Los Castillos de Guayana (C), Ciudad Bolivar (CB), and Ciudad Guayana (CG) were the sampling sites. Freshwater physicochemical parameters pH, conductivity, and DO were measured in situ at each sample site. Twenty-four bottom sediment samples were collected with an Eckman grab, dried, and sieved. Trace elements Pb, Cr, Cu, Cd, Ti, and Co were measured in sediments with grain sizes <63μm. Bottom sediment analysis followed EPA method 3050B (digestion with HNO3 + HCl + H2O2). Statistical analyses included the Shapiro-Wilk test, Spearman correlation, Kruskal-Wallis test, and principal component analysis (PCA). Physicochemical parameters highlighted the marked difference between the left and the right river margins, reflecting the cross-channel heterogeneity due to the dissimilar geology and low horizontal mixing. Metal concentrations were generally low, with higher variations associated with urban and industrial sources. Pb, Cr, Cu, Cd, Ba, Ti, and Co concentrations did not generally indicate significant pollution, but potential contamination from sewage and industrial effluents was noted. The differences between the two river margins were common in all the sampling sites, reflecting the sources of water biochemistry related to geochemical origins in the Andes and the Guiana Shield, respectively. The study emphasizes the importance of sampling location within the river channel.

Holocene dust activity in inland Asia driven by both the mid-latitude Westerlies and the East Asian winter monsoon

Inland Asia is a major global source of dust and the dust transport from this region has global implications. However, the processes and forcing mechanisms of dust activity in inland Asia during the Holocene are still debated due to the lack of high-quality records with accurate dating, unambiguous dust signals, and a high resolution. Here we present a well-dated record of dust activity based on the Ti content of the sediments of Shuanghu Lake, in the southern Altai Mountains, with a ~ 15-yr-resolution and covering the entire Holocene. This record shows a gradual decrease in dust intensity during ~11.7–6 thousand years ago (ka), followed by a persistent increase since ~6 ka. Frequent dust events are also evident, lasting hundreds of years, and are superimposed on the millennial-scale trend, corresponding to the nine North Atlantic Bond events. We propose that the millennial-scale trend of dust activity was primarily influenced by variations in the mid-latitude Westerlies, while the dust events on the centennial scale were driven primarily by a strengthened East Asian winter monsoon. Overall, this study provides a reliable, high-resolution record of Holocene dust activity in inland Asia, and it updates the previous view that dust activity in this region was solely controlled by the mid-latitude Westerlies or the Siberian High. Our findings contribute to an improved understanding of global dust transport with implications for predicting future dust activity in this region.

Genetic Type and Formation Evolution of Mantle-Derived Olivine in Ultramafic Xenolith of Damaping Basalt, Northern North China Block

Olivine in deep-seated ultramafic xenoliths beneath the North China Block serves as a crucial proxy for decoding the compositions, properties, and evolution of the lithospheric mantle. Here, we conduct an investigation on olivine (including gem-grade) hosted in ultramafic xenoliths from Damaping basalt in the northern part of the North China Block. This contribution presents the results from petrographic, Raman spectroscopic, and major and trace elemental studies of olivine, with the aim of characterising the formation environment and genetic type of the olivine. The analysed olivine samples are characterised by high Mg# values (close to 91%) possessing refractory to fertile features and doublet bands with unit Raman spectra beams of 822 and 853 cm−1, which are indicative of a forsterite signature. Major and trace geochemistry of olivine indicates the presence of mantle xenolith olivine. All the analytical olivine assays ≤0.1 wt % CaO, ~40 wt % SiO2, and ≤0.05 wt % Al2O3. Furthermore, olivine displays significantly different concentrations of Ti, Y, Sc, V, Co, and Ni. The Ni/Co values in olivine range from 21.21 to 22.98, indicating that the crystallisation differentiation of basic magma relates to oceanic crust recycling. The V/Sc values in mantle/xenolith olivine vary from 0.54 to 2.64, indicating a more oxidised state of the mantle. Rare earth element (REE) patterns show that the LREEs and HREEs of olivine host obviously differentiated characteristics. The HREE enrichments of olivine and the LREE depletion of clinopyroxene further assert that the mantle in the Damaping area underwent partial melting. The wide variations of Mg# values in olivine and the Cr# values in clinopyroxene, along with major element geochemistry indicate transitional characteristics of different peridotite xenoliths. This is possibly indicative of a newly accreted lithospheric mantle interaction with an old lithospheric mantle at the time of the basaltic eruption during the Paleozoic to Cenozoic.

Fe-isotopic evidence for hydrothermal reworking as a mechanism to form high-grade Fe-Ti-V oxide ores in layered intrusions

The genesis of high-grade Fe-Ti-V oxide ores (up to >90 vol%) in layered intrusions remains highly debated. Here, on example of Hongge layered intrusion in China, we show that hydrothermal dissolution and precipitation of Fe-Ti-V oxides played a critical role in forming high-grade massive ore deposits as demonstrated by textural-compositional evidence and in-situ iron isotope data (δ56Fe), analyzed with femtosecond laser ablation multicollector (LA-MC-) ICP-MS. Hongge is a mafic layered intrusion composed of a Lower olivine clinopyroxenite Zone (LZ), a Middle clinopyroxenite Zone (MZ), where thick massive ore layers (with up to 90 % Fe-Ti-V oxides) formed, and an Upper gabbro Zone (UZ). Magnetite in Hongge exhibits two contrasting generations: 1) Mag1, observed in all lithological zones and formed at the magmatic stage, has extensive ilmenite exsolution lamellae and high Ti and Cr content. The δ56Fe of Mag1 shows considerable variations from −0.23 to 0.63 ‰ and strikingly an offset of ∼0.3 ‰ towards lower values in the massive ore zone compared to the zones below and above; 2) Mag2, concentrated mainly in thick massive ore layers in MZ without exsolution lamellae, is almost pure magnetite (with low Ti, Al content) and has extremely low δ56Fe values (−1.24 to −0.09 ‰), indicating precipitation from Fe-enriched hydrothermal fluids. Similarly, the δ56Fe of ilmenite shows significant variations from −1.08 to −0.27 ‰ and is significantly lower than typical values for igneous ilmenite (−0.4–0 ‰). Ilmenite displays a similar Fe isotope variation pattern to Mag1 along the stratigraphic position, i.e., with significantly lower δ56Fe in the massive ore zone. As magnetite and ilmenite together contain essentially all Fe, the isotopic shift of these minerals in the ore zone translates to a bulk isotopic offset of ∼−0.3 ‰ compared to the zones below and above. This requires a bulk flux of isotopically light Fe resulting in Fe enrichment in this zone to form massive or even monomineralic ores. The very light isotopic values, particularly hydrothermal magnetite (Mag2) and petrologic evidence, strongly indicate that the Fe flux into the massive ore layers occurred during hydrothermal reworking. This scenario is furthermore supported by magnetite-ilmenite elemental and isotopic thermometry, according to which Fe-Ti oxides experienced hydrothermal re-equilibration in a temperature range of 400–300 °C. Iron isotopic mass balance calculations imply that ∼20–30 % of the Fe in the thick massive ore layers may result from secondary enrichment through hydrothermal precipitation, significantly increasing the ore tonnages and grades. Potentially, other layered intrusions experienced similar mechanisms of hydrothermal Fe enrichment, which will have to be proven in future investigations.

Na5/6[Ni1/3Mn1/6Fe1/6Ti1/3]O2 as an Optimized O3-Type Layered Oxide Positive Electrode Material for Sodium-Ion Batteries.

Layered oxides, such as NaxMeO2 (Me = transition metal, x = 0-1), are believed to be the most promising positive electrode materials for Na-ion batteries because of their high true density, large capacities, high working potentials, and reversibility. This study identified Na5/6[Ni1/3Mn1/6Fe1/6Ti1/3]O2 as an optimal composition for use as an O3-type positive electrode material in Na-ion batteries on the basis of a comprehensive phase diagram, where the end members of the triangular phase diagram were Na2/3[Ni1/32+Mn2/34+]O2, Na2/3[Ni1/32+Ti2/34+]O2, and the hypothetical composition Na4/3[Ni1/32+Fe2/33+]O2. By investigating the effects of the partial substitution of Mn4+ with Fe3+ and Ti4+ within the Na(2/3+x)[Ni1/3Mn(2/3-x-y)FexTiy]O2 system, we optimized the capacity, working potential, and cycle performance. Substitution with Fe enhanced the discharge capacity due to the increased Na+ content in the initial composition, although it also led to a reduced cycling stability derived from irreversible Fe migration to the Na layers. In contrast, substitution with Ti improved the working potential and cycling stability, although an excessive Ti content caused capacity degradation with cycling. We found that the O3-type Na5/6[Ni1/3Mn1/6Fe1/6Ti1/3]O2 demonstrated an excellent cycle stability with minimal capacity loss over 250 cycles, which was attributed to the suppression of irreversible transition metal migration.

Enhanced Surface Mechanical and Tribological Properties of H13 Die Steel with TiAlSiN Coating Deposited by HiPIMS

TiAlSiN is a potential protection coating for die steel to improve the surface hardness, anti-wear performance and suitability. In the present study, TiAlSiN is deposited on H13 die steel by high power impulse magnetron sputtering and the effects of bias voltage, deposition temperature, and film thickness on the performance of coatings are studied. The microstructure, mechanical and tribological properties of coatings are analyzed by energy dispersive spectrometer, X-ray diffraction, nanoindentation, friction and wear tests. The results show that with the changes of sputtering parameters, the content of Ti, Al, Si, and N fluctuates slightly. With the increase of bias voltage, deposition temperature and film thickness, the diffraction peaks of Ti3Al2N2 phase become wider. Higher bias voltage, deposition temperature, and film thickness are beneficial for obtaining coatings with high hardness, and strong wear resistance. By observing the surface morphology of coatings after grinding with Si3N4 balls, it was found that the wear mechanism of coatings contains abrasive wear, fatigue wear, and oxidative wear.

Medium-entropy Zr–Nb–Ti alloys with low magnetic susceptibility, high yield strength, and low elastic modulus through spinodal decomposition for bone-implant applications

Medium-entropy Zr–Nb–Ti (ZNT) alloys are being extensively investigated as load-bearing implant materials because of their exceptional biocompatibility and corrosion resistance, and low magnetic susceptibility. Nevertheless, enhancing their yield strength while simultaneously decreasing their elastic modulus presents a formidable obstacle, significantly constraining their broader utilization as metallic biomaterials. In this study, three medium-entropy ZNT alloys, i.e., Zr45Nb45Ti10, Zr42.5Nb42.5Ti15, and Zr40Nb40Ti20 (denoted ZNT10, ZNT15, and ZNT20, respectively), were designed based on the miscibility gap in the ZNT phase diagram and prepared by annealing of cold-rolled ingots. Their microstructures, mechanical properties, wear resistance, corrosion resistance, magnetic susceptibility, and biocompatibility were systematically studied. Spinodal decomposition occurred in the cold-rolled ZNT10 and ZNTi15 after annealing at 650°C for 2 h and resulted in nanoscale Zr-rich β1 and (Nb, Ti)-rich β2 phases, which significantly improved their yield strength and reduced their elastic modulus. The wear resistance of the alloys decreased with an increase in Ti content. Dense ZrO2, Nb2O5, and TiO2 oxide layers were formed during the polarization process in Hanks’ solution, which enhanced the corrosion resistance of the alloys. These ZNT alloys exhibited significantly lower magnetic susceptibility than medical Ti alloys. The ZNT alloys showed a cell viability of more than 94 % toward MG-63 cells after culturing for 3 d. Overall, the spinodal ZNT15 showed the best combination of mechanical properties, wear resistance, corrosion resistance, low magnetic susceptibility, and sufficient biocompatibility among the three alloys. Statement of SignificanceThis work reports on medium-entropy Zr–Nb–Ti (ZNT) alloys with heterostructure. Spinodal decomposition significantly improved their mechanical strength and reduced the elastic modulus of the alloys. The wear resistance of the ZNT alloys decreased with an increase in Ti content. Dense ZrO2, Nb2O5, and TiO2 oxide layers were formed during the polarization process in Hanks’ solution, which enhanced the corrosion resistance of the alloys. The ZNT alloys exhibited significantly lower magnetic susceptibility than medical Ti alloys. The ZNT alloys showed a cell viability of more than 94% toward MG-63 cells after culturing for 3 d. The results demonstrate that spinodal ZNT alloys have enormous potential as bone-implant materials due to their outstanding overall mechanical properties, high corrosion resistance, wear resistance, low magnetic susceptibility, and sufficient biocompatibility.

Tunable TiO2‐Heterophase Junctions for Studying and Enhancing Photocatalytic H2 Production Under Visible Light

AbstractPhotocatalytic performance of titanium dioxide under visible light was optimized by preparing heterophase compounds (containing two or more phases) by hydrolysis method using TiCl4 as a precursor with different concentrations (0.5, 0.7, 1, and 2) to adjust condensation modes of Ti4+. The structural and textural properties of the synthesized TiO2 multiphase were fully characterized by XRD, Raman scattering, FTIR, BET, MEB‐EDX, XPS, diffuse UV–vis, and EIS spectroscopy. The increase of TiCl4 amount precursor has a significant effect on the heterophase junctions of TiO2 structure and more especially on textural and structural properties. The best specific surface area (131 m2/g) is observed for the sample at high Ti‐content (2 in Ti4+). The anatase phase (79%) is detected only for 0.5 in Ti4+ sample. However, both rutile (R) and brookite (B) phases are present in 0.7, 1, and 2 Ti‐contents. On the one hand, the band gap of 2.9 eV allows titanium dioxide to be active under visible light. In addition, the presence of rutile/brookite heterophase junction contributes significantly to the improvement of active sites for photocatalytic reaction. The separation efficiency of photogenerated electrons and holes contributes to photocatalytic evolution performance under visible light for hydrogen production. The optimal sample (0.7 content in Ti+4 species) which presents in its structure 52% of rutile and 46% of brookite phases presented the highest photocatalytic activity with a 230 µmol/h of hydrogen generation, attributed to the heterophase junctions R52/B46, highly pore size 20.60 nm, and relatively small bandgap energy 2.974 eV. This work opens new horizons on the creation and study of a multiphase TiO2 that works under visible light in the fields of renewable energies and various other fields.

Geochronological and geochemical constraints on the multistage magmatic processes of the Lianhuashan batholith, South China: Implications for the petrogenesis and polymetallic mineralization

The Lianhuashan batholith, which is a composite pluton located in the middle part of a world-class giant tungsten (W) polymetallic belt of South China, hosts a huge reserve of more than 50000 t of W. Despite this great economic significance, the petrogenesis of each phases of the Lianhuashan batholith, as well as its temporal and genetic relationships to the W polymetallic mineralization, is still unclear. To address these questions, we conducted a comprehensive study for the Lianhuashan batholith, including LA-ICP-MS zircon U-Pb dating, whole-rock geochemical and in-situ mineral trace element analyses. Different from previous studies, four main granitic phases (G1 to G4) were identified. The biotite granite (G1) formed from 168.6 to 165.3 Ma, has the lowest Si content and high Al and Fe contents, and is significantly depleted in Ba, Sr, Ti, P, and Nb whereas enriched in U, Hf, Zr, and Y contents. In contrast, the two-mica granite (G2) and fine-grained muscovite granite (G3), formed from 162.8 to 160.5 Ma, exhibit similar characteristics including enrichment in La, Y, Hf, Th, U, and depletion in Ba, Sr, and P. The porphyritic granite (G4) is the latest magmatic phase and formed at 158.3 Ma. It is characterized by high K, Si, Th, U, Zr, Hf contents but low Al, Fe, Sr, P, and Ti contents. These features support that four main phases of the Lianhuashan batholith belong to S-type granites that experienced significant fractional crystallization, and display reduced and low temperature features. Combined with previously published studies, we suggest that the Lianhuashan batholith formed in an intraplate extensional setting triggered by the high-angle rollback subduction of the paleo-Pacific plate. The three early phases (i.e., G1–G3) are in turn more oxidized and are responsible for the transition from Sn- to W-dominated mineralization. In contrast, the G4 granite, characterized by lower oxygen fugacity, is resposible for Pb-Zn-Ag-U polymetallic mineralization.

Rare earth element distribution and microstructure characteristics of Ti(C,N)-based cermets with added La2O3

The effects of different levels of La2O3 content (0, 0.1, 0.2, and 0.6 wt%) in Ti(C,N)-based cermets prepared via vacuum sintering on their final microstructures as well as on the distribution characteristics of La were explored. Specifically, La2O3 was expected to undergo a reduction reaction during the sintering process when surrounded by components with carbon-donating abilities, which was proven by the formation of carbon-deficient phases, the distribution characteristics of La, and thermodynamic calculations. Metallic La, reduced from La2O3, was preferentially distributed around the Ti(C,N) particles during the heating stage and ultimately diffused into the ceramic phase, including black core–grey rim, white core–grey rim, and black rimless grains. Due to interface purification, adding a moderate amount of La2O3 could decrease the particle size of the black cores and make the core–rim structures more orderly. Along with the increase of La2O3, both the size and volume fraction of the white cores increased. However, adding an excessive amount of La2O3 would result in non-uniform distribution of the core–rim and binder phases. The inward migration of La to the ceramic phase leads to smaller lattice parameters forthe core–rim structure and a larger lattice misfit at the core/rim interfaces.

Plant enzymatic activity as an indicator of nano-TiO2 exposure in rice ecosystems

The widespread use of nano-titanium dioxide (nano-TiO2) has raised concerns about its environmental impact, particularly in soil-plant systems. This study investigates the effects of nano-TiO2 on rice (Oryza sativa cv. PB1121) growth and enzymatic activities, compared to bulk TiO2, through a pot culture experiment. Eight doses of Ti were applied: six as soil treatments (0, 2.5, 5, 10, 25, and 50 mg Ti kg⁻¹) and two as foliar treatments (0.05 % and 0.1 %). Results showed that grain yield peaked at 25 mg Ti kg⁻¹ soil for both nano and bulk TiO2, while a 0.05 % foliar spray outperformed by 0.1 %. Titanium accumulated mostly in roots, followed by straw and grains. Nano-TiO2 significantly increased antioxidant enzyme activities—catalase (CAT), superoxide dismutase (SOD), guaiacol peroxidase, and ascorbate peroxidase (APX)—and lipid peroxidation (measured as malondialdehyde) in rice roots and shoots, indicating oxidative stress. The findings suggest that plant enzymatic activity serves as an early indicator of nano-TiO2 exposure, making it a valuable biomarker for environmental monitoring. However, higher Ti doses may inhibit plant growth depending on Ti source and concentration. Further studies should examine the effects of nano-TiO2 of different sizes, shapes, and charges on various crops and soil types to validate these results and assess the broader implications for agricultural and environmental health. This research highlights the dual potential of nano-TiO2 as both a growth enhancer and a stress-inducing agent, emphasizing the need for careful management in agricultural applications.

Measurements of F1‐ Region Ionosphere State Variables at Arecibo Through Quasi Height‐Independent Exhaustive Fittings of the Incoherent Scatter Ion‐Line Spectra

AbstractWe discuss an exhaustive search approach to fit the incoherent scatter spectrum (ISS) in the F1‐region for molecular ion fraction (fm), ion temperature (Ti), and electron temperature (Te). The commonly used “full profile” approach for F1‐region measurements parameterizes the molecular ion fraction as a function of altitude and fits all the related heights for the state variables. In our approach, we fit the ISS at each height for fm, Ti, Te, and ion velocity (Vi) independently. Our exhaustive search method finds all the major local minima at each altitude. Although a parameterized function is used to guide the algorithm in finding the best solution, the fitting parameters retain their local characteristics. Despite that fitting fm, Ti, and Te without constraints requires Doppler shift to be accurately determined and the ISS signal‐to‐noise ratio higher than the full‐profile method, simulations show that Ti, Te, and fm can be recovered within a few percent accuracy with a moderate signal‐to‐noise ratio. We apply the exhaustive search approach to the Arecibo high‐resolution incoherent scatter radar data taken on 13 September 2014. The derived ion and electron temperatures are sensitive enough to reveal thermosphere gravity waves commonly seen in the electron density previously. Our method is more robust than previous height‐independent fitting methods. Comparison with another Arecibo program indicates our results are likely more accurate. Simultaneous high‐resolution measurements of Ti, Te, fm, Vi, and electron concentration (Ne) in our approach open new opportunities for synergistic studies of the F1‐region dynamics and chemistry.

Study on microstructure characteristics and hole expansion mechanism of Ti–Nb–V microalloyed 900 MPa hot-rolled ferrite-bainite high hole expansion steel

In this study, a 900 MPa grade hot-rolled ferrite/bainite high hole expansion steel was developed using thermomechanical controlled processing (TMCP) and medium-temperature coiling with a Ti–Nb–V multi-microalloy design. The effects of cooling rates and coiling temperatures on the microstructure, mechanical properties, and hole expansion behavior were systematically investigated. The steel, coiled at 600 °C and cooled at a controlled rate (10–25 °C/s), demonstrated an excellent balance of strength and ductility, achieving a tensile strength of 901 MPa and elongation of 23%. The microstructure consisted of approximately 62% ferrite and 38% bainite, characterized by a uniform and fine grain distribution. The high coiling temperature increased the content of Ti–Nb–V composite precipitates, while reduced cooling times promoted the formation of smaller precipitates primarily along dislocation lines and grain boundaries. A hole expansion ratio of 77% was achieved due to the optimized grain morphology and phase ratio, with refined grains and high-angle grain boundaries impeding crack propagation. Additionally, the increased presence of secondary precipitates strengthened the soft phase ferrite and enhanced the coordinated deformation between ferrite and bainite. These combined effects significantly improved the steel's resistance to crack propagation during hole expansion, making it a promising material for applications requiring high strength and formability.

Tracking hydrothermal particles from the ridge axis to the sediment column along the Endeavour segment of the Juan de Fuca Ridge

Elemental fluxes associated with mid-ocean ridge hydrothermal systems are thought to be important in the ocean budgets of many elements but quantitative models of these fluxes, and how they vary in space and time due to different boundary conditions, are in their infancy. This is especially true for non-conservative elements that can be involved in multiple processes transforming them between the dissolved and particulate phases both in the water column and after sedimentation. To help develop a more robust database for parameterizing the processes operating, we undertook a coupled sediment trap and sediment core study of hydrothermal sediments on the west flank of the Endeavour segment of the Juan de Fuca Ridge. Sediment traps deployed in the Main Endeavour Field (MEF) and 3 and 9 km southwest of this field, along the mean flow direction of the hydrothermal plume, show that the rate of change of the concentration of sulfide-associated elements (Cu, Zn, Cd, Pb, Ag, As, Mo) in sediment settling from the plume differs between elements. We interpret this as indicating both different dissolution rates of phases containing these elements and different rates of scavenging of these elements from seawater. Scavenging is most readily tracked using elements for which the scavenged fraction is large relative to the hydrothermally derived fraction. For such elements, the relative efficiency of scavenging from seawater (REE > Cr > Ni > V > P > U) matches that previously reported from the TAG system on the Mid-Atlantic ridge despite different vent fluid and seawater chemistries that are expected to lead to both differing roles of Fe-sulfide and Fe-oxyhydroxides and different Fe oxidation rates. In the sediment trap samples collected 9 km off-axis, but not in those collected 3 km off-axis, the Mn and Ti concentrations correlate strongly despite these samples having much higher Mn concentrations than background sediment. Since Ti is sourced almost entirely from background terrigenous material such a correlation was not expected. The most reasonable explanation for this is that aggregation of hydrothermally derived particles with terrigenous material settling through the water column controls removal of hydrothermally derived particles from the water column. Changes in sediment composition with depth in the off-axis sediment core, along with differences between the composition of material from the sediment core and the off-axis sediment traps, are interpreted as indicating large post-deposition changes in sediment composition. For example, much or all of the Mn, P, As and Mo carried to the sediments with hydrothermally derived particles is released back into the water column during diagenesis. In contrast, V and REE concentrations in the sediment core are higher than those in the off-axis sediment trap samples, which may be due to continued scavenging in a benthic boundary layer post-deposition. Overall these data are interpreted as indicating that the net loss of many elements from the non-buoyant plume may not be a proxy for loss from the ocean, and a better understanding of post-depositional processes in hydrothermal settings may be important in understanding cycling of the aforementioned elements, and likely others, in seawater.

Improving flexural performance of repaired C/C composites through Ti addition: Mechanism analysis

Ti-doped Ni-based solder was used as the repair agent to recover the flexural performance of the damaged carbon/carbon (C/C) composites. The effects of the contents of Ti on the microstructure, chemical compositions, and flexural strength were investigated. The thermal stress distribution and repair mechanism was studied by finite element analysis methods. The addition of an appropriate amount of Ti enhanced the wetting performance of the repair agent on the surface of C/C composites. Besides, the TiC hard particles formed at the interface provided strengthen effect, and form a gradient structure of coefficient of thermal expansion (CTE), thereby enhancing the interface bonding ability and improving the flexural performance of the repaired C/C composites. The flexural strength was the highest with a recovery rate of 92.6 % when the content of Ti was 5 wt%. This work provides a strategy for the engineering application and improving the damage repair of C/C composites.