Ti Peaks Research Articles

Effect of CTAB and NaBH4 Solutions on Ti and Cu Nanoparticles Prepared by Pulsed Laser Ablation

The effect of different media, including cetyltrimethylammonium bromide (CTAB) and sodium borohydride (NaBH4), on the size, shape, optical absorption, and stability of titanium (Ti) and copper (Cu) nanoparticles (NPs) synthesized by laser ablation in liquid, was investigated. Ti and Cu NPs were fabricated by irradiating Ti and Cu targets using a Nd:YAG pulsed laser with a wavelength of 1064 nm, an energy of 500 mJ, repetition rate of 1 Hz, and a number of pulses of 1000. Results showed the direct effect of the type of surfactant on the size and size distribution of Ti and Cu NPs under the same laser ablation parameters. Morphological properties were described by field emission scanning electron microscope (FESEM) images, which revealed the formation of semispherical particles. The EDS results confirmed the spike-induced synthesis of Ti and Cu in CTAB and NaBH4 solutions. The transmission electron microscopy (TEM) images showed the nanostructures of Ti and Cu with spherical particles. The UV-vis absorption spectra showed that the absorption peak of Ti was almost constant at 289 nm, while the peak of Cu disappeared for both solutions. Zeta potential analysis showed that NPs prepared in CTAB solution were more stable than those in NaBH4 solution.

Monitoring of UV-A radiation by TiO2/CdS nanohybrid along with the high on-off ratio

Exposure to UV-A light can have detrimental effects on human health, leading to skin damage and an increased risk of skin cancer. In this study, we employed a hydrothermal-assisted method to cultivate TiO2-decorated CdS nanorods for use in UV photodetectors. Our research culminated in the fabrication of an exceptionally responsive and rapid photodetector based on the TiO2/CdS nanohybrid. X-ray diffraction analysis revealed the hexagonal phase of CdS nanorods, predominantly oriented along the (002) plane, and the presence of the anatase phase of TiO2. Scanning electron microscopy (SEM) measurements confirmed the nanorod structure of TiO2/CdS. Optical properties of the TiO2/CdS nanohybrid were investigated through UV–visible absorbance analysis. Additionally, X-ray photoelectron spectroscopy (XPS) provided insights into the surface composition of the prepared nanohybrid, with peaks corresponding to Cd 3d3/2 and Cd 3d5/2 at binding energies of 411.47 eV and 404.73 eV, respectively, and confirming the presence of titanium through peaks of Ti 2p3/2 and 2p1/2 at binding energies of 458.31 eV and 463.8 eV, respectively. Raman analysis indicated the presence of the anatase phase of TiO2 in the composite. Our device exhibited an impressive detectivity of 9.9 × 1012 Jones, an EQE (external quantum efficiency) of 971.36%, and a high photoresponsivity of 2.86 A/W. These results suggest that TiO2/CdS nanohybrids, prepared using a cost-effective and straightforward method, hold promise for UV photodetection applications.

CHARACTERIZATION OF CORROSION BEHAVIOR OF INCONEL 617 WELDED JOINTS USING CMT-GMAW MULTI-CONTROL WELDING

This work addressed the effect of CMT-GMAW multi-control welding of Inconel 617 alloy with different wire feed rates (8.9, 9.4, and 9.9 m/min) on the microstructure, hardness, and electrochemical properties. The weld joints are composed of columnar dendritic structure with cellular crystals. Electron backscattered diffraction (EBSD) study showed equiaxed dendrite at the center of weld metal with growth direction perpendicular to the fusion boundary. The weldments showed diffraction peaks at 43.53[Formula: see text], 50.12[Formula: see text], and 74.82[Formula: see text], and these peaks mainly represent gamma ([Formula: see text]) and gamma prime ([Formula: see text]) phases along with the carbide peaks of Ti (C, N), M[Formula: see text]C6 and M6C. The Base metal (BM) had a lower hardness (232 ± 10 HV[Formula: see text]) and lower corrosion rate (0.212 mpy) than the weld joints. The increase in wire feed rate (WFR) results in the decrease of microhardness (267 ± 5 − 251 ± 6 HV[Formula: see text]) and increase in corrosion rate (1.833-28.140 mpy). The base metal exhibited higher potential ([Formula: see text]) and lower current density ([Formula: see text]) than the weld joints. As wire feed rate (WFR) increases, heat input increases; solidification time increases, grain boundaries coarsen, resulting in a lower grain boundary (GB) density, and hence increased carbide precipitation and segregation in weld zone leading to higher stable anodic current density, which caused corrosion resistance to deteriorating. The BM was more corrosion resistant than the weld joints. The metallurgical and physical changes caused by the welding process affect the corrosion resistance of the weld joints. This leads to the weld metal corroding faster than the base metal.

Exploring the bioactivity of reduced graphene oxide and TiO2 nanocomposite for the regenerative medicinal applications

Millions of people globally suffer from issues related to chronic wounds due to infection, burn, obesity, and diabetes. Nanocomposite with antibacterial and anti-inflammatory properties is a promising material to promote wound healing. This investigation primarily aims to synthesize reduced graphene oxide and titanium dioxide (rGO@TiO2) nanocomposite for wound healing applications. The rGO@TiO2 nanocomposite was synthesized by the one-step hydrothermal technique, and the physicochemical characterization of synthesized nanocomposite was performed by X-ray diffraction, Fourier transforms infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and dynamic light scattering. Further, the nanocomposite antibacterial, cytotoxicity, and wound-healing properties were analyzed by disc diffusion method, MTT assay, and in vitro scratch assay, respectively. Based on the TEM images, the average particle size of TiO2 nanoparticles was around 9.26 ± 1.83 nm. The characteristics peak of Ti–O–Ti bonds was observed between 500 and 850 cm−1 in the Fourier transforms infrared spectrum. The Raman spectrum of graphene oxide (GO) was obtained for bands D and G at 1354 cm−1 and at 1593 cm−1, respectively. This GO peak intensity was reduced in rGO, revealing the oxygen functional group reduction. Moreover, the rGO@TiO2 nanocomposite exhibited dose-dependent antibacterial properties against the positive and negative bacterium. The cytotoxicity for 5–100 µg/mL of rGO@TiO2 nanocomposite was above the half-maximal inhibitory concentration value. The in vitro scratch assay for rGO@TiO2 indicates that the nanocomposite promotes cell proliferation and migration. The nanocomposite recovered the wound within 48 h. The rGO@TiO2 nanocomposite shows potential materials for wound healing applications.

Cryogenian-Ediacaran crustal growth and evolution of the active margin of the Dahomeyide belt, Ghana

AbstractThe study presents detailed petrographical, geophysical, structural and geochemical data of the internal nappes zone to establish the deformational history, origin and tectonic setting and constrain the crustal growth and evolution of the active margin of the Dahomeyide belt. Two main lithological units, (i) deformed meta-granitoids (migmatites and gneisses) and (ii) undeformed granitoids, dominate the internal nappes zone. The granitoids are generally I-type, metaluminous to weakly peraluminous, low-K tholeiite to high-K calc-alkaline and of tonalite, granodiorite and granite affinity. The overall trace element patterns of the studied granitoids characterized by the enriched LILE and depleted HFS, with negative peaks of Nb-Ta, Sr, P and Ti, are indications of arc-related magmatism. Structural analysis reveals four deformation phases (D1-D4). D1 represents Northwest-Southeast (NW-SE) Pan African shortening associated with a continent-continent collision, resulting in westward nappe stacking. Progressive NW-SE shortening resulted in D2 and D3 top-to-the-NW dextral and sinistral thrusting events during the Pan-African orogeny. D4 is an extensional event likely associated with the orogenic collapse phase. The gneisses and migmatites, with dominant axial planar foliations, point to their formation in a collisional setting or influence by the Pan-African collisional processes. Continental-arc signatures in these rocks imply continental subduction during their protolith formation. The intrusive granitoid and pegmatite are undeformed, meaning late- to post-orogenic emplacement. These findings suggest that the internal nappes zone archived the subduction-collision and post-collisional phase of the Pan-African orogeny and recorded large-scale migmatization and granitoid emplacement due to partial melting of thickened lower crust between Mid-Cryogenian and late Ediacaran.

In‐house manufactured benchtop XRF spectrometer

AbstractThe growing efficiency of agribusiness depends on the development of technology. A key challenge regards the determination of plant mineral content, which help farmers to make a decision about fertilizer use. Currently, such nutritional status diagnoses are made based on wet chemical methods; they are usually slow and generate chemical wastess. In this context, an in‐house manufactured XRF benchtop for agri‐samples is proposed in this study. This XRF system was furnished with a manual primary filter changer, vacuum chamber, dual interlock radiological protection system, which were installed in the equipment cover, and light signals. Analytical capabilities were also evaluated. The equipment presented spurious peaks of Ti, Fe, Ni, and Zn, which is not ideal for some agronomical applications; this issue might be overcome in the future by means of additional primary filters. The total x‐ray spectrum counting rate is roughly one magnitude order lower than two other commercial XRF systems, but the signal‐to‐noise ratio is quite similar. The vacuum chamber under partial vacuum improves the Al, Si, P and S signals from 1.5 to 2.2. The limits of detection (LOD, mg kg−1) for P (261), S (168), K (68), and Ca (50) macronutrients and Mn (14), Fe (15), Cu (9), and Zn (8) micronutrients are close to the ones reported in the literature. The limits of detection for P, S, K, and Ca are suitable for plant analysis.

Effect of Mo2C addition on the formation of core-rim structure and mechanical properties of Ti(C,N)-WC-Mo2C-(Ni, Co) cermet

Ti(C,N)-based cermets with various Mo2C contents (4, 6, 8, 10, 12 and 14 wt%) were fabricated via vacuum hot-pressing sintering. The results showed that the cermets were comprised of coarse hard phase with a core-rim structure and partial fine rimless hard phase, embedded in Ni/Co binder matrix. Mo2C inhibits the rim growth on the coarse hard phase and hinders the dissolution of the fine rimless hard phase, which improves the mechanical properties of cermets. In addition, with the increasing Mo2C content, a bimodal pattern of X-ray diffraction peaks of (Ti,W,Mo) (C,N) solid solution can be observed, which indicates that high content of Mo2C has a different effect on the W and Mo contents in the white core-grey rim and black core-grey rim hard phase. When the Mo2C addition reaches 12 wt%, the cermet exhibits better wear resistance, which is attributed to a film composed of Ti and Mo oxides formed on the sliding interface. This work provides fundamental knowledge about the formation of core-rim structure and mechanical properties of Ti(C,N)-based cermets with various Mo2C contents.

Constraints on Paleoproterozoic crustal growth from Birimian Supergroup lavas of the Bui belt (Ghana) in the West African Craton

The volcano-metasedimentary Bui belt in Ghana is one of the lesser known Birimian belts of the West African Craton that provide constraints on Paleoproterozoic crustal growth. This study presents the first major, trace element and Nd-Hf isotope data for the mafic suite of the Bui belt to constrain their petrogenesis and geodynamic setting. Although alteration is prevalent, the volcanic, volcaniclastic and plutonic rocks show tholeiitic signatures, with Mg# 35–65. Chondrite-normalised REE patterns are mainly flat, with slight LREE enrichment or depletion, and multi-element diagrams show Th and LREE depletion relative to other immobile incompatible trace elements. These features suggest derivation from a moderately depleted mantle source. Whole rock Sm-Nd isotope data yields an errorchron at ca. 2.2 Ga, with an initial εNd of +3.4 but the Lu-Hf isotopic system appears to be disturbed. The lack of arc related geochemical signatures (absence of negative Nb-Ta and Ti peaks, a nearly flat to depleted REE pattern) in the Bui mafic suite, together with the volcanic-sedimentary rock association, point towards magma generation in an oceanic plateau or divergent setting similar to a mid-ocean ridge, contrasting with the subduction setting that has been proposed for most other instances of Birimian magmatism in the West African Craton.

Discussion: “Effects of acid concentration on the recovery of rare earth elements from coal fly ash” [Mokoena et al., 2022, Int. J. Coal Geology, volume 259, article 104037

The contribution by Mokoena et al. (2022, volume 259, article 104037) is flawed in the fundamental characterization of the fly ash. The TESCAN Integrated Mineral Analyzer (TIMA) is a tool designed for use with several-micron-scale crystalline particles, not for a fly ash largely composed of glass with nm-scale to micron-scale minerals. The Energy Dispersive X-ray Spectroscopy analysis is flawed by the selection of rare earth peaks that are either concealed by the stronger Ti and Fe peaks or cannot be distinguished from the background in the energy regions outside of the Ti and Fe peaks. Consequently, many of the minerals “identified” in the TIMA analysis were mistakenly considered to have observable concentrations of rare earth elements.

Preparation of Ti<sub>3</sub>C<sub>2</sub> nanowires with cross-linked network structure and its application in lithium-sulfur batteries

<p indent="0mm">Lithium-sulfur batteries are considered as one of the most promising next-generation energy storage devices due to their high energy density and low cost, but their development and application still face many challenges such as the shuttle effect of lithium polysulfide. Recently, a new type of two-dimensional material, MXene (e.g., Ti₃C₂), has attracted much attention. The high specific surface area, high electrical conductivity and polar surface of Ti₃C₂ make it an ideal sulfur host for lithium-sulfur batteries. However, two-dimensional Ti₃C₂ nanosheets (Ti₃C₂-NS) are easy to aggregate together, which reduces the contact area between them and sulfur, and results in the performance degradation of the sulfur electrode. In this work, Ti₃C₂ nanowires (Ti₃C₂-NW) with cross-linked structure are successfully synthesized by etching the exfoliated Ti₃C₂ nanosheets in NaOH solution. Subsequently, sulfur-loaded Ti₃C₂-NW (Ti₃C₂-NW@S) is prepared by the melt-impregnation method and used as the positive electrode material for lithium-sulfur batteries. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images show that Ti₃C₂-NW is composed of cross-liked nanowires with a width of <sc>5–10 nm,</sc> and sulfur particles are successfully loaded in the cross-linked network structure of Ti₃C₂-NW. Moreover, the EDX element mapping images show that the elemental distribution of S is consistent with those of C, O and Ti, further confirming the high dispersion of sulfur particles in Ti₃C₂-NW. Subsequently, Ti₃C₂-NW is characterized by using nitrogen adsorption and desorption technique. The type IV isotherm indicates that Ti₃C₂-NW has a mesoporous structure and its specific surface area is <sc>124.6 m² g⁻¹.</sc> XPS analysis proves the interaction between Ti atoms on the surface of Ti₃C₂-NW and S atoms from sulfur particles because of the presence of Ti-S peak in the high-resolution Ti 2p and S 2p XPS spectra. The loading of sulfur in Ti₃C₂-NW@S (~71 wt%) is determined by thermogravimetric analysis (TGA). It is also found that the type of Ti₃C₂ precursor used for etching affects the structure of the product. Selecting the multilayer Ti₃C₂ particles as the Ti₃C₂ precursor for etching in NaOH solution can only obtain the composite of Ti₃C₂ nanowires and nanosheets (Ti₃C₂-NWS). For comparison, sulfur-loaded Ti₃C₂-NS (Ti₃C₂-NS@S) and sulfur-loaded Ti₃C₂-NWS (Ti₃C₂-NWS@S) are prepared and used as the positive electrode material for lithium-sulfur batteries. The cyclic voltammogram of Ti₃C₂-NW@S shows two reduction peaks and an oxidation peak, corresponding to lithiation of sulfur. Note that the potential difference of redox peak of Ti₃C₂-NW@S is smaller than that of Ti₃C₂-NWS@S, implying the smaller electrode polarization and faster redox reactions of sulfur within Ti₃C₂-NW. The electrochemical impedance spectroscopy (EIS) test results show that Ti₃C₂-NW@S has lower charge transfer resistance (<italic>R</italic>_ct = 7.35 Ω) than Ti₃C₂-NWS@S (<italic>R</italic>_ct = 28.38 Ω), also revealing the rapid reaction of sulfur with Li⁺ on Ti₃C₂-NW. Accordingly, compared to Ti₃C₂-NS@S and Ti₃C₂-NWS@S, Ti₃C₂-NW@S exhibits better electrochemical performance, such as a reversible capacity of <sc>658 mA h g⁻¹</sc> at <sc>0.2 C</sc> after 100 cycles, and a capacity of <sc>436 mA h g⁻¹</sc> at <sc>1 C</sc> after 300 cycles. The superior electrochemical performance of Ti₃C₂-NW@S is attributed to the large specific surface area and mesoporous structure of Ti₃C₂-NW@S, which effectively provide the space for high loading of sulfur and accommodate the volume expansion of sulfur during the lithiation process. Moreover, the large surface area of Ti₃C₂ nanowires is conducive to capturing the lithium polysulfide and thereby suppressing the shuttle effect of lithium polysulfides. Meanwhile, the cross-linked structure is also favorable to the diffusion of lithium ions. This study shows that modifying the morphology and structure of Ti₃C₂ can effectively improve its electrochemical performance as the sulfur host for lithium-sulfur batteries and expand its application in other energy fields.

Corrigendum: Preparation of an In2S3/TiO2 Heterostructure for Enhanced Activity in Carbon Dioxide Photocatalytic Reduction

In the original article, the XPS results shown in Figure 4 contain some errors resulting from an issue with the instrument used to record the data. The data were remeasured and the corrected results are shown in the replacement Figure 4 presented below. Several affected sentences (page 440, left column, second paragraph) reporting data from Figure 4 require correction and have been reproduced below with the corrected text indicated in bold. … As shown in Figure 4a, the XPS spectrum of the In2S3/TiO2 in the In 3d region shows two peaks at 452.2 and 444.6 eV corresponding to In 3d3/2 and In 3d5/2, respectively. Figure 4b exhibits the high-resolution spectrum of Ti 2p. Peaks of Ti 2p3/2 and Ti 2p1/2 are clearly observed at 458.9 eV and 464.6 eV, respectively, which also confirm that the valence states of Ti is tetravalent. The O 1s peaks (Figure 4c) located at 531.6 eV and 530.0 eV are ascribed to the surface-adsorbed oxygen and TiO2 lattice oxygen. According to Figure 4d, S 2p3/2 and S 2p1/2 are clearly observed at 162.2 eV and 161.0 eV, respectively… (a–d) XPS spectra of In 3d, Ti 2p, O 1s and S 2p in 5 % In2S3/TiO2. The authors confirm that these changes do not affect the overall conclusions of the manuscript. The authors apologize for these errors and for any inconvenience caused.

Influence of Mo–Nb–Ti additions and peak annealing temperature on the microstructure and mechanical properties of low alloy steels after ultrafast heating process

Abstract The influence of the heating rates from 10 to 1000 °C/s and annealing temperatures on the microstructure and mechanical properties of two 0.2%C, 1.9%Mn, 1.4%Si cold-rolled steels with and without the addition of carbide-forming elements (Mo, Nb, and Ti) have been investigated. Results show that the increase of the heating rate above 100 °C/s refines the parent austenitic grains in both alloys. The increment of the heating rate led to carbon heterogeneities in the austenite, which after subsequent cooling promoted the formation of a complex mixture of fine-grained constituents. As expected, at the lower heating rates the presence of Nb and Ti-rich carbides and carbonitrides controls the austenite grain growth during the annealing treatment. The tensile test results reveal that high heating rates do not have a significant influence on the tensile strength of the alloy with carbide-forming elements. On the other hand, both the ultimate tensile strength (UTS) and total elongation of the alloy without carbide-forming elements decrease, due to the formation of bands of ferrite and high carbon martensite. However, samples treated at heating rates above 100 °C/s show a combination of UTS in the range of 1400–1600 MPa, and 12–18% of total elongation. The results suggest that the microstructure heterogeneity obtained after high heating rates, especially the ferrite content, has the major effect on the mechanical behavior of the studied steels.

Synthesis and Characterization of Amorphous TiO2 Anode Prepared by Anodizing Method for Na-ion Batteries

Sodium ion battery (SIB) has engage sustainable alternative on replacing lithium ion batteries. The lower potential and larger ionic value has demanded on seeking a potential anode materials. Amorphous TiO2 prepared by electrochemical anodisation technique has provide a suitablility as anode SIB materials, which approved by conducting XRD, FTIR, and SEM-EDX measurements. Electrochemical performance was tested with variations in the concentration of NaOCl4 electrolyte in propylene carbonate (PC) solvent. Diffractogram of TiO2 showed the only peaks of Ti was observed at 2θ = 40.34. The TiO2 IR spectrogram shows that the absorption band at 507 cm-1 is the peak of the vibration characteristics of the Ti-O bond and the peak of 975 cm-1 corresponds to Ti-O-Ti bond. SEM-EDX image analysis showed the morphology of TiO2 was smooth without pore with a ratio of Ti: O elemental composition of 1: 2. Voltammogram showed the anodes in 0.5 M NaOCl4 electrolyte in PC solvent has a good stability potential windows with the high current density 1.2 mA and the capacity of 0.037 F/g

Topographic characterization of cp-Ti implants with machined and modified surface by LASER

This study characterized the topography osseointegrated implants (cp-Ti) with machined surface (MS), laser beam surface (LS) and laser beam surface followed by deposition of sodium silicate (SS) by means SEM-EDX, roughness measurements, cross-sectional roughness, contact angle, X-ray diffraction (XRD) and laser confocal optical perfilometry. The SEM of MS showed smooth surface, contaminated with machining residues, while LS and SS rough surfaces with a more regular and homogeneous morphological pattern. The EDX showed Ti peaks for MS and Ti and oxygen for LS and SS. The mean roughness values of LS and SS were statistically higher (p &lt;0.05) than MS. The contact angle of LS and SS was 0º. The XRD of MS showed only Ti peaks, while LS and SS showed the presence of oxides and nitrides and presence of sodium silicate. The surface treatment performed in the LS and SS promoted important modifications in the topography and physical-chemical properties.

Effects of Mg-Al Alloy and Pure Ti on High Temperature Wetting and Coherency on Al Interface Using the Sessile Drop Method

In this study, high temperature wetting analysis and AZ80/Ti interfacial structure observation are performed for the mixture of AZ80 and Ti, and the effect of Al on wetting in Mg alloy is examined. Both molten AZ80 and pure Mg have excellent wettability because the wet angle between molten droplets and the Ti substrate is about 10° from initial contact. Wetting angle decreases with time, and wetting phenomenon continues between droplets and substrate; the change in wetting angle does not show a significant difference when comparing AZ80-Ti and Mg-Ti. As a result of XRD of the lower surface of the AZ80-Ti sample, in addition to the Ti peak of the substrate, the peak of TiAl3, which is a Ti-Al intermetallic compound, is confirmed, and TiAl3 is generated in the Al enrichment region of the Ti substrate surface. EDS analysis is performed on the droplet tip portion of the sample section in which pure Mg droplets are dropped on the Ti substrate. Concentration of oxygen by the natural oxide film is not confirmed on the Ti surface, but oxygen is distributed at the tip of the droplet on the Mg side. Molten AZ80 and Ti-based compound phases are produced by thickening of Al in the vicinity of Ti after wetting is completed, and Al in the Mg alloy does not affect the wetting. The driving force of wetting progression is a thermite reaction that occurs between Mg and TiO2, and then Al in AZ80 thickens on the Ti substrate interface to form an intermetallic compound.

Sedimentary rhythm of Mn-carbonate laminae induced by East Asian summer monsoon variability and human activity in Lake Ohnuma, southwest Hokkaido, northern Japan

Past and ongoing precipitations of Mn-carbonate (rhodochrosite) have occurred in the freshwater Lake Ohnuma, which is situated about 8 km south of the Hokkaido-Komagatake volcano, southwest Hokkaido (northern Japan). Lake sediments from a surface and a longer ∼4 m core contain the sedimentary rhythms of rhodochrosite laminae and volcanic deposits which were identified by nondestructive micro-XRF fluorescence analyses. The three tephra ash layers from the Hokkaido-Komagatake volcano, characterized by peaks of Al, Si, K, Ca, and Ti, correspond to regionally recognized tephras (1640, 1929 and 1996 CE) based on ashfall isopachs and 137Cs, 210Pb and 14C ages determined from the two cores. The sedimentation rate showed a drastic change around 1929 CE; ∼0.3 cm/yr for 1640–1929 CE and ∼2.7 cm/yr for 1929–2012 CE. The Mn content record of Lake Ohnuma sediments, composed of rhodochrosite laminae, showed a periodic variation with a decadal–centennial scale over the interval 1640–2012 CE. Sediment petrography and hydrochemical measurements suggest that the metastable phase of rhodochrosite was deposited during summer after being precipitated, followed by the crystal growth of rhodochrosite within the anoxic sediments. On the basis of these results, high Mn content is interpreted as an indicator of strengthened summer stratification associated with reduced rainfall runoff. The Ti/Si ratios are representative of the relative abundance of detrital inputs from the watershed. The combined signals of elevated Mn content and Ti/Si ratio for 1935–2012 CE indicate eutrophication and hypoxia in the lake and enhanced land erosion in the watershed, associated with the post-1970s intensive land use such as livestock farming. For 1640–1935 CE, the Lake Ohnuma record shows an antiphase relationship between the Mn content and Ti/Si ratio, which implies that the detrital inputs reflected the strength of the East Asian summer monsoon (EASM), and the reduced rainfall runoff resulted in weaker mixing, followed by depleted O2 in the water column. The antiphase variation in Mn content and Ti/Si ratio suggest weak EASM during the Little Ice Age (∼1850 CE), followed by strong EASM between 1860 and 1929 CE.

Influence of 3d Transition Metal Impurities on Garnet Scintillator Afterglow

Garnet scintillators often suffer from undesired afterglow, the origin of which is not always well-understood. A possible origin is contamination with transition metal (TM) ions. These impurities can act as traps giving rise to afterglow. Alternatively, they may show long-lived (microsecond) d–d emission. Here we present a systematic study on the role of 3d TM impurities in (Lu,Gd)3(Ga,Al)5O12 garnet scintillators. Scintillator disks intentionally doped with ppm levels of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn were studied to identify TM-related traps in thermoluminescence (TSL) glow curves and their role in afterglow. For Ti, V, and Cr additional TSL peaks were observed that gave rise to RT afterglow in the 10–2–103 s time range, depending on garnet composition. On the millisecond time scale long-lived red/near-infrared emission was observed from Mn and Fe impurities, explained by spin-forbidden d–d emission. We show that afterglow can be reduced by the use of ultrapure raw materials. Other solutions include bandgap engineering for the garnet host to modify trap depths and applying optical filters to block the spin-forbidden d–d emission. The present study provides an insightful overview of the role of 3d TM impurities on afterglow in Ce-doped scintillators and procedures to predict and reduce afterglow. These insights will aid the development of Ce-doped garnets with superior afterglow behavior.

Vapor plume and melted zone behavior during dissimilar laser welding of titanium to aluminum alloy

The present study deals with continuous Yb:YAG laser welding of pure titanium to aluminum alloy A5754 performed with different beam offsets to the joint line. Spectroscopic and morphological characterization of vapor plume exiting the keyhole was combined with post-mortem observation and energy-dispersive X-ray spectroscopy (EDX) analysis of the welds. The laser beam centered on the joint line resulted in periodic transversal inclination of a vapor jet on the aluminum side associated with a local increase of melt width and an intense spatter formation. Such behavior can be attributed to the instability of the keyhole wall from the aluminum side. The beam offset on the titanium side led to the stabilization of vapor plume, the attenuation of spattering, and a minimal mixing between the two liquid metals. On the contrary, the beam offset on the aluminum side produced a violent formation of spatters and a highly unstable, diffuse vapor jet. In this case, the liquid metals underwent a violent mixing that was progressively reduced along with the decrease in quantity of melted Ti. The observed spectral regions contained the emission peaks of neutral Ti and Mn. Very few emission lines of Al were observed, because they require higher excitation energies compared to Ti and Mn. Boltzmann linearization using Ti emission peaks allowed the estimation of vapor temperature to be between 5000 and 6000 K, except for the welds with the beam offset on Al.

Effect of titanium dioxide on the structural and electrical conductivity of cadmium oxide

Paint pigments belong in the daily-uses classification which are required to have a certain set of substantial qualities, such as; it is needed to be corrosion proof, rust proof (which further leads to longer life), thermally stable, should not react with the environment etc. Sol-Gel Auto-combustion and Ultrasonic Assisted Sol-Gel method was employed on to obtain CdO and TiO2 nanopowders respectively and their composite mixture was studied to understand the outcomes of incorporating TiO2 in another metal oxide CdO. The structural and morphological studies of the pure and the blended composition were analysed with the help of XRD, FTIR, Raman Spectroscopy and FESEM while the conductive nature was investigated through Maxwell-Wagner model and Koop’s phenomenological theory. The formation of CdO and anatase TiO2 was confirmed through XRD with the emergence of standard peaks for both the mentioned metal oxides. The characteristic FTIR peaks were acquired for CdO (410.05–678.41 cm−1) and TiO2 (845.45–850.87 cm−1 and 1391.45 cm−1) and the standardised Raman peaks were also obtained for both CdO (144.66–954.01 cm−1) and TiO2 (147.49–634.52 cm−1). The FESEM study showed the structural formation for CdO and TiO2 while the EDX analysis showed the emergence of peaks of Cd, O & Ti for the studied sample cases. The Dielectric Analysis revealed the drop in the conductive graph. The fore-mentioned composite sample can have its consideration for the raw materials used in paints.

Bone regeneration around implants with modified surface by acid conditioning with the fluoride ions deposition

Aim Evaluate the late bone regeneration around implants with machined (MS) and acid modified surfaces followed by the deposition of fluoride ions (AFS) in the tibiae of rabbits. Materials and methods Ti-cp disks and implants underwent the topographic characterization before surgery through scanning electron microscope, x-ray energy dispersive spectrometer (SEM-EDX), roughness average (Ra) and, cross section. Six rabbits received 12 implants in their tibiae. After 12 weeks, euthanasia was performed. The percentage of bone interface contact (BIC%) and neoformed bone area (NBA%) was measured. Data were submitted to the statistical analysis. Results SEM-EDX revealed smooth surface, contaminated with machining residues and peaks of Ti for MS group and AFS group, peaks and valleys with presence of Ti, O, Na, Cl and F. Ra showed statistical difference between AFS (1.34 ± 0.35 µm) than MS (0.4 ± 0.06 µm). Cross section showed a mean thickness of 7.84 ± 3.73 μm for ASF and 1.26 ± 0.55 μm for MS. The mean values of BIC% for AFS were statistically higher than MS. For NBA% there is no statistical difference between grups. Conclusions The surface modified by acid conditioning followed the addition of fluoride ions provides superior osseointegration process, even in the later periods of bone regeneration.