Search Results (311)

Rare-earth elements (REEs), including lanthanides, scandium, and yttrium, are important for advanced technologies such as renewable energy systems, electronics, medical diagnostics, and precision agriculture. Despite their relative crustal abundance, REE extraction is impeded by complex geochemical behavior, dispersed distribution, and environmental challenges. This review presents a comprehensive overview of REE geochemistry, mineralogy, and major deposit types including carbonatites, alkaline igneous rocks, laterites, placer deposits, coal byproducts, and marine sediments. It also highlights the global distribution and economic potential of key REE projects. The integration of machine learning has further enhanced exploration by enabling deposit classification and geochemical modeling, especially in data-limited regions. Environmental and health challenges associated with REE mining, processing, and electronic waste (e-waste) recycling are studied, along with the expanding use of REEs in agriculture and medicine. Some recycling efforts offer promise for supply diversification, but significant technological and economic barriers remain. Ensuring a secure and sustainable REE supply will require integrated approaches combining advanced analytics, machine learning, responsible extraction, and coordinated policy efforts. The present review offers a general overview that can be useful for informing future studies and resource-related discussions. Full article

Objectives: This review examines the efficacy of each laser type in the field of periodontal surgery and analyzes published articles that focus on the use of lasers in periodontal surgery. Methods: Automatic and manual searches were made in 3 separate databases (PubMed, Embase, and Cochrane) with the aim of finding all published articles of the last 15 years up until December 2023 that describe the clinical manipulation of diode, erbium:yttrium-aluminum-garnet (Er:YAG), erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG), neodymium yttrium-aluminum-garnet (Nd:YAG), and carbon dioxide (CO₂) lasers for periodontal surgical procedures in humans. Results: A total of 18 studies were selected for inclusion, all of which compared the usage of a laser type to conventional periodontal surgical techniques with their main follow-ups being in 3, 6, or 9 months. Conclusions: There are a variety of laser types, each with different settings and wavelengths, that can be applied to the established aspects of resective and regenerative periodontal surgeries. A significant majority of the publications, 10 of the 12 studies, that include diode lasers as an adjunctive show an improvement in clinical results compared to traditional surgical techniques alone, while 2 articles studied the Er:YAG laser and 1 article studied the Er,Cr:YSGG laser, with all 3 of them failing to completely test their therapeutic capabilities and indicating similar results to conventional surgery. The Nd:YAG laser was featured in 3 studies, with 1 study showing superior results for the laser group, another study showing the negative influence of the laser, and the 3rd study being inconclusive. The CO₂ laser was used in 1 study and showed better clinical results for the laser group. Diode lasers have been proven to produce additional therapeutic results, but there is a need for further investigation of erbium family lasers along with the Nd:YAG and CO₂ lasers, as the current provided literature contradicts their potential healing capabilities. Full article

Background and Objectives: Conventional methods for removing cemented fixed prosthetic restorations (FPRs) are unreliable and lead to unsatisfactory outcomes. At their best, they allow the tooth to be saved at the expense of a laborious process that also wears down rotating tools and handpieces and occasionally results in abutment fractures. Restorations are nearly never reusable in any of these situations. Erbium-doped yttrium-aluminum-garnet (Er:YAG) and erbium-chromium yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers casafely and effectively remove FPRs, according to scientific studiesre. This study sets out to examine the impact of Er:YAG laser radiation on the debonding of different ceramic restorations, comparing the behavior of various ceramic prosthetic restoration types under laser radiation action and evaluating the integrity of prosthetic restorations and dental surfaces exposed to laser radiation. Materials and Methods: The study included a total of 16 removed teeth, each prepared on opposite surfaces as abutments.y. Based on the previously defined groups, four types of ceramic restorations were included in the study: feldspathic (F), lithium disilicates (LD), layered zirconia (LZ), and monolithic zirconia (MZ). The thickness of the prosthetic restorations was measured at three points, and two different materials were used for cementation. The Er:YAG Fotona StarWalker MaQX laser was used to debond the ceramic FPR at a distance of 10 mm using an R14 sapphire tip with 275 mJ, 20 Hz, 5.5 W, with air cooling (setting 1 of 9) and water. After debonding, the debonded surface was visualized under electron microscopy. Results: A total of 23 ceramic FPRs were debonded, of which 12 were intact and the others fractured into two or three pieces. The electron microscopy images showed that debonding took place without causing any harm to the tooth structure. The various restoration types had the following success rates: 100% for the LZ and F groups, 87% for the LD group, and 0% for the MZ group. In terms of cement type, debonding ceramic FPRs cemented with RELYX was successful 75% of the time, compared to Variolink DC’s 69% success rate. Conclusions: In summary, the majority of ceramic prosthetic restorations can be successfully and conservatively debonded with Er:YAG radiation. Full article

Background/Objective: Noninvasive PET imaging-based assessment of PD-L1 expression is of high clinical value for better patient selection and treatment response rates to PD-L1 immunotherapies. Due to their shorter biological half-life and faster clearance from the blood pool, radiolabeled antibody fragments are an attractive alternative for imaging than their full-length IgG counterpart. This work investigated the radiosynthesis and in vitro cell uptake of anti-PD-L1-B11-nanobody radiolabeled with ⁴⁴Sc (t_1/2 = 4.04 h) as an alternative to anti-PD-L1-B11-IgG, better suited for longer half-life radioisotopes such as ⁸⁹Zr (t_1/2 = 78.41 h). Methods: The proteins were conjugated with p-SCN-Bn-DTPA and radiolabeled at room temperature with ⁴⁴Sc, achieving a radiochemical yield of a RCY of 94.8 ± 3.1% (n = 3) for [⁴⁴Sc]Sc-B11-IgG and 73.6 ± 12.1% (n = 3) for [⁴⁴Sc]Sc-B11-nanobody, before purification. Results: Significantly higher uptake in the PD-L1₊ cells than PD-L1_KO cells was observed for both probes. However, high non-specific uptake, particularly of the radiolabeled B11-nanobody, was also observed which may negatively impact its potential as a molecular imaging probe. Conclusions: Due to the high non-specific uptake in vitro, the ⁴⁴Sc radiolabeled nanobody was not progressed to further in vivo evaluation. These results should, however, not discourage future evaluations of other nanobody based probes radiolabeled with ⁴⁴Sc, due to their well-matched biological and physical half-life. Full article

This article explores how alloy composition, hardness, and machining parameters can affect the cutting forces encountered in aluminum–lithium (Al-Li)-based alloys. By analyzing Cu and Cu with Sc additions to Al-Li alloys and exposing them to various heat treatments to modify their hardness, this research was designed to evaluate milling performance under various feed rates, cutting speeds, and cooling conditions. The findings indicate that increased hardness leads to higher cutting forces, with Al-Li-Cu-Sc exhibiting the greatest resistance due to scandium’s grain-refining effect and the formation of stable precipitates. Statistical analyses identify the feed rate as the main parameter controlling cutting force, along with hardness and cooling conditions. Notably, wet machining consistently reduces cutting forces, especially in Al-Li-Cu-Sc alloys, enhancing machinability when using high cutting speeds. This work underscores the significance of selecting optimal machining parameters tailored to specific alloy compositions. These findings contribute to improved process efficiency, reduced tool wear, and enhanced productivity. Given the attractive characteristics of these alloys, i.e., their low weight and high strength, the insights from this study are particularly beneficial for aerospace applications where machining performance directly impacts component quality, cost, and overall operational efficiency. Full article

MIL-STD-1530D and the United States Air Force (USAF) Structures Bulletin EZ-SB-19-01 require an ability to predict the growth of naturally occurring three-dimensional cracks with crack depths equal to what they term an equivalent initial damage size (EIDS) of 0.254 mm. This requirement holds for both additively manufactured and conventionally built parts. The authors have previously presented examples of how to perform such predictions for additively manufactured (AM) Ti-6Al-4V; wire arc additively manufactured (WAAM) 18Ni 250 Maraging steel; and Boeing Space, Intelligence and Weapon Systems laser bed powder fusion (LPBF) Scalmalloy^®, which is an additively manufactured Aluminium-Scandium-Mg alloy, using the Hartman-Schijve crack growth equation. In these studies, the constants used were as determined from ASTM E647 standard tests on long cracks, and the fatigue threshold term in the Hartman-Schijve equation was set to a small value (namely, 0.1 MPa √m). This paper illustrates how this approach can also be used to predict the growth of naturally occurring three-dimensional cracks in WAAM CP-Ti (commercially pure titanium) specimens built by Solvus Global as well as in WAAM-built Inconel 718. As in the prior studies mentioned above, the constants used in this analysis were taken from prior studies into the growth of long cracks in conventionally manufactured CP-Ti and in AM Inconel 718, and the fatigue threshold term in these analyses was set to 0.1 MPa √m. These studies are complemented via a prediction of the growth of naturally occurring three-dimensional cracks in conventionally built M300 steel. Full article

The implementation of theranostics in oncologic nuclear medicine has exhibited immense potential in improving patient outcomes in prostate cancer with the implementation of [⁶⁸Ga]Ga-PSMA-11 PET and [¹⁷⁷Lu]Lu-PSMA-617 into clinical practice. However, the correlation between radiopharmaceutical biodistributions seen with [⁶⁸Ga]Ga-PSMA-11 PET imaging and downstream [¹⁷⁷Lu]Lu-PSMA-617 therapy remains imperfect. This suggests that prostate cancer theranostics could potentially be further refined through the implementation of true theranostics, tandem pairs of diagnostic and therapeutic radiopharmaceuticals that utilize the same ligand and element, thus yielding identical pharmacokinetics. The radioscandiums are one such group of true theranostic radiopharmaceuticals. The radioscandiums consist of two β+ emitting scandium isotopes (⁴³Sc/⁴⁴Sc), as well as a β⁻ emitting therapeutic isotope (⁴⁷Sc), which can all conjugate with PSMA-targeting PSMA-617. This potential has led to extensive investigations into the production of the radioscandiums as well as pre-clinical assessments with several ligands; however, there is a lack of literature extensively describing the complete synthesis of scandium radiopharmaceuticals. which therefore limits the accessibility of radioscandium research in theranostics. As such, this work aims to present an easily translatable protocol for the synthesis of [⁴³Sc]Sc-PSMA-617 from a [⁴²Ca]CaCO₃ starting material, including target formation, nuclear production via ⁴²Ca(d,n)⁴³Sc reaction, chemical separation, radiolabeling, solvent reformulation, and target recycling. Full article

In this study, we aimed to investigate the occurrence of rare earth elements (REEs) in commonly consumed foods and assess the dietary exposure risks among different age groups in Zhejiang Province. The results showed that tea and shrimp had the highest REE detection rates, reaching 100%. Of all the food categories examined, tea exhibited the highest REE concentrations, significantly exceeding those in other foods. This may be attributed to differences in moisture content, root absorption mechanisms, and processing methods. The concentration pattern of REEs in all samples occurred in the following order: cerium > lanthanum > yttrium > neodymium > neodymium > scandium > praseodymium > gadolinium > dysprosium. The light REEs/heavy REEs (HREEs) ratio was consistently > 2 but remained lower than the ratios observed in the soil and sediments, indicating a potential risk of HREE enrichment. Dietary exposure assessments revealed that the total REE intake among Zhejiang residents was below the established safety threshold (51.3 µg/kg BW/day), with children experiencing the highest exposure (3.71 µg/kg BW/day), primarily due to their lower body weight. In the assessment of individual rare earth elements, Ce exposure in children aged ≤ 6 years exceeded the toxicological reference value. However, this threshold was established based on studies in pregnant and lactating populations and might not be directly applicable to young children. Therefore, overall dietary exposure to individual REEs remains within safe limits. REE exposure from tea consumption did not pose a health risk, even for habitual tea drinkers. These findings underscore the importance of continuous monitoring of REE accumulation in food and additional research on the potential long-term health effects, even though the current exposure levels of REEs are below the established safety limit. This is especially important considering the bioaccumulative nature of REEs and the limited paucity of toxicological data, particularly in vulnerable populations. Full article

Highly (0002)-oriented Al_1−xSc_xN thin films with different Sc doping concentrations (x = 0, 0.2, 0.25, 0.3, and 0.43) were prepared via a magnetron sputtering system. The effects of Sc doping on the crystal structure and electrical property of the as-prepared thin films were investigated experimentally. The results of synchrotron radiation grazing-incidence wide-angle X-ray scattering (GIWAXS) and X-ray diffraction (XRD) demonstrated that the Sc³⁺ substitution for Al³⁺ induced asymmetric lattice distortion: the a-axis exhibited monotonic expansion (reaching 3.46 Å at x = 0.43) due to the larger atomic radius of Sc (~0.87 Å), while the c-axis attained a maximum value of 5.14 Å at x = 0.2 and subsequently contracted as the bond angle reduction became dominant. The dielectric constant increased to 34.67 (225% enhancement) at x = 0.43, attributed to the enhanced polarization of Sc-N bonds and interfacial charge accumulation effects. Simultaneously, the dielectric loss increased from 0.15% (x = 0) to 6.7% (x = 0.43). Leakage current studies revealed that high Sc doping (x = 0.43) elevated the leakage current density to 10⁻⁶ A/cm² under an electric field of 0.2 MV/cm, accompanied by a transition from Ohmic conduction to space-charge-limited current (SCLC) at a low electric field strength (<0.072 MV/cm). Full article

The historical industrial waste deposit Gater was used to dispose of different metallurgy wastes from lead and zinc production. The metallurgical waste deposit was situated in the open space, between the tailing waste deposit Žitkovac and river Ibar flow. Large amounts of lead-containing wastes are produced in the non-ferrous metallurgical industry, such as lead ash and lead slag generated in Pb smelting, lead anode slime, and lead sludge produced in the raw lead refining process. In addition to the lead concentration, numerous valuable components are found in the lead refinery waste from the group of Critical Raw Materials, such as antimony, arsenic, bismuth, copper, nickel, magnesium, scandium, as well as Rare-Earth Elements. Samples with eight characteristic points were taken to obtain relevant data indicating a possible recycling method. The chemical composition analysis was conducted using ICP; the scanning was completed using SEM-EDS. The mineralogical composition was determined by using XRD. The chemical analysis showed a wide range of valuable metal concentrations, from Ag (in the range from 14.2 to 214.6, with an average 86.25 mg/kg) to heavy metals such as Cu (in the range from 282.7 to 28,298, with an average 10,683.7 mg/kg or 1.0683% that corresponds to some active mines), Ni and Zn (in the range from 1.259 to 69,853.4, with an average 14,304.81 mg/kg), Sc (in the range from 2.4 to 75.3, with an average 33.61 mg/kg), Pb (in the range from 862.6 to 154,027.5, with an average 45,046 mg/kg), Sb (in the range from 51.7 to 18,514.7, with an average 2267.8 mg/kg), Ca (in the range from 167.5 to 63,963, with an average 19,880 mg/kg), Mg (in the range from 668.3 to 76,824.5, with an average 31,670 mg/kg), and As (in the range from 62.9 to 24,328.1, with an average 5829.53 mg/kg). The mineralogy analysis shows that all metals are in the form of oxides, but in the case of As and Fe, SEM-EDS shows some portion of elemental lead, pyrite, and silica-magnesium-calcium oxides as slag and tailing waste residues. The proposed recovery process should start with leaching, and further investigation should decide on the type of leaching procedure and agents, considering the waste’s heterogeneous nature and acidity and toxicity. Full article

To enhance the mechanical properties of 6082 aluminum alloy, a novel Sc- and Zr-microalloyed 6082 alloy was fabricated through squeeze casting technology. Microalloying with Sc and Zr substantially refined the microstructure of alloy, achieving an average grain size of 136.36 μm—a 31.7% reduction compared to the baseline 6082 alloy. Furthermore, the addition of Sc and Zr effectively refined the coarse AlFeMnSi intermetallic phases, mitigating their inherent brittleness. The Sc/Zr-modified alloy exhibited delayed age-hardening kinetics, requiring 100% longer aging time to reach peak hardness due to Sc/Zr-induced retardation of β’’-phase precipitation. The optimized alloy demonstrated better mechanical properties, showing 10.4%, 8.0%, and 71.8% enhancements in yield strength, ultimate tensile strength, and elongation, respectively, over the non-microalloyed counterpart. The squeeze-cast Sc/Zr-modified alloy valve body showed yield strength exceeding 300 MPa and elongation above 10% across various sections, which verifies the effectiveness of this integrated microalloying and forming approach. Full article

This study proposes an innovative health management solution to address the defecation care needs of the elderly population. Traditional post-defecation care methods have significant limitations, particularly imposing a considerable psychological burden on patients. By leveraging the rich physiological information contained in bowel sounds, in this work, we designed and implemented a wearable defecation warning monitor based on scandium aluminum nitride (ScAlN) piezoelectric thin films and piezoelectric micromachined ultrasonic transducers (PMUTs). The proposed device mainly incorporates two core components: a bowel sound signal acquisition module and a real-time signal display graphical user interface (GUI) developed using the MATLAB R2023a platform. The research focuses on the systematic characterization and comparative analysis of the sound pressure sensitivity of three different signal readout structures. Experimental results demonstrate that the differential readout structure exhibits superior sensitivity. By continuously monitoring bowel sounds in healthy subjects both with and without the urge to defecate using the defecation warning monitor and a modified stethoscope, and conducting a comparative analysis of the experimental data, it is verified that the defecation warning monitor has significant advantages in clinical applications and demonstrates promising potential for defecation warning monitoring. Full article

In this study, we characterize electrocaloric lead scandium tantalate (PST) samples by means of the adiabatic temperature change $\Delta T_{\mathrm{ad}}$ and the dissipative heat $q_{\mathrm{diss}}$ with a direct thermal method. The figure of merit ($FOM$), defined as the ratio between the adiabatic temperature change and the thermal hysteresis, quantifies the losses of the material. Additionally, it is also possible to draw conclusions on the efficiency of a caloric cooling system based on the regenerator or cascaded approach. The maximum adiabatic temperature change of the measured samples results in $\Delta T_{\mathrm{ad},\max }=(1.39\pm 0.02)$ K and the dissipative heat yields $q_{\mathrm{diss}}=(0.39\pm 0.05) \mathrm{J}/(\mathrm{k}\mathrm{g} \mathrm{K})$, resulting in an $FOM=(5.1\pm 0.2)$. The efficiency for an ideal cascaded system is given by ${\eta }_{\mathrm{cas}}=0.56$, and for the ideal regenerator, the efficiency is given by ${\eta }_{\mathrm{reg}}=0.84$. The results demonstrate that the PST material in this study exceeds the maximum $FOM$ in the literature by 34%. Full article

In recent years, implantable medical devices (IMDs) have introduced groundbreaking solutions for managing various health conditions. However, traditional implanted batteries necessitate periodic surgical replacement and tend to be relatively bulky, posing significant inconvenience to patients. To overcome these limitations, researchers have investigated various wireless power transfer (WPT) techniques, among which the ultrasonic wireless power transmission (UWPT) technique has distinct advantages. However, limited research has been conducted on ultrasonic power transfer at lower operating frequencies. Therefore, this study explores wireless power transfer using scandium-doped aluminum nitride (AlScN) piezoelectric micro-electromechanical transducers (PMUTs) in deionized (DI) water. Experimental results indicate that at an operating frequency of 14.075 kHz, the power transfer efficiency (PTE) can reach up to 2.68% under optimal load resistance conditions. Furthermore, a low-frequency UWPT system based on a AlScN PMUT has been developed, delivering a stable 3.3 V output for implantable medical devices and contributing to the advancement of a full-spectrum UWPT framework. Full article

An innovative design of a hydrophone based on a piezoelectric composite film of $AlN/S{c}_{0.2}A{l}_{0.8}N$ is presented. By designing a non-uniform composite sensitive layer, the dielectric loss and defect density are significantly reduced, while the high-voltage electrical characteristics of scandium-doped aluminum nitride are retained. X-ray diffraction analysis shows that the sensitive films have excellent crystal quality (FWHM is 0.34°). According to the standard underwater acoustic calibration test, the device exhibits full directivity with a minimum deviation of ±0.5 dB at 1 kHz frequency, sound pressure sensitivity of −162.9 dB (re: 1 V/$\mathsf{\mu }$Pa) and equivalent noise density of 46.1 dB (re: 1 $\mathsf{\mu }$Pa/√Hz). The experimental results show that the comprehensive performance of the piezoelectric heterostructure hydrophone meets the standard of commercial high-end hydrophones while maintaining mechanical stability, and provides a new solution for underwater acoustic sensing. Full article