Search Results (185)

Erbium-165 (¹⁶⁵Er) is an Auger electron emitter with 7.2 electrons per decay and very few other emissions, making it an interesting candidate for Auger electron therapy. We present here a procedure for producing ¹⁶⁵Er by the ^natHo(p,n)¹⁶⁵Er nuclear reaction on a 16.5 MeV medical cyclotron. The target was prepared by pressing a Ho₂O₃:Al 1:1 (w/w) powder mixture on a Ag disc with a cylindrical depression in the center. With a 0.1 mm Nb foil in front, degrading the energy to 15 MeV, and water cooling at the back of the Ag disc, the target could withstand irradiation at currents up to 45 µA without showing any signs of damage. The beam tolerance of the target was also estimated by calculating the temperature and heat dissipation in the target via the numerical solution of the heat transport equations. For a 180 mg target, the production yield was 12.3 ± 1.9 MBq/µAh. The separation of two neighboring lanthanides is challenging, which led us to study the distribution coefficients for Er and Ho on commercially available LN2 resin for both HNO₃ and HCl eluents. Based on these values, we propose a purification procedure involving two successive LN2 columns for separating the ¹⁶⁵Er from Ho and Al, followed by a small TK221 column to concentrate the final eluate. No radionuclidic impurities were detected, and the chemical impurities found in the final formulation were traces of Ho, Er, Ca, Pb, and Fe. For three different chelators (DOTA, DTPA, and CHX-A″-DTPA), the effective molar activity of the final formulation was measured. The stability of the three complexes formed was also assessed upon incubation in mouse serum for 28 h. Full article

Polymer films of nickel Schiff-base complexes were investigated to clarify degradation mechanisms induced by coordinating impurities—specifically, the protic solvents methanol and isopropanol. Films of poly[Ni(Salen)] and its sterically protected derivatives were electropolymerized in situ and subjected to cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM) measurements in dry acetonitrile electrolyte with 1% vol. alcohol added. In situ monitoring of redox activity and mass changes revealed something. It was revealed that traces of alcohols act as axial ligands to the Ni center. This disrupts the conjugated π-system and conductivity of the polymer. The rate of electrochemical stability strongly depends on the complex structure. The unsubstituted poly[Ni(Salen)] film showed the fastest loss of capacity in both methanol and isopropanol, whereas complexes with methyl substituents in the diimine bridge (poly[Ni(Salpn-1,2)] and poly[Ni(Saltmen)]) exhibited significantly improved stability. EQCM measurements revealed irreversible changes in the mass of all polymer films upon exposure to alcohol-containing electrolytes. These observations are consistent with the axial coordination of alcohol molecules to the Ni centers and the concomitant ingress of solvent species into the polymer matrix. The results demonstrate that molecular design—specifically, introducing steric hindrance around the metal center—markedly enhances resistance to coordinating impurities. Full article

In this investigation, the local mode model for C-H overtone transitions in hydrocarbons and the thermal lens (TL) technique are used to obtain vibrational overtone spectra and subsequent analysis of hydrocarbon impurities in liquid solutions. The experimental thermal lens design enables the detection of hydrocarbon solutes in trace amounts within a hydrocarbon solvent by exciting two distinct vibrational overtones. To exemplify the method, we present the thermal lens signal corresponding to the (Δυ = 6) overtone of benzene or naphthalene as impurities in solvents such as n-hexane or iso-octane. The lowest composition recorded for benzene in n-hexane was 0.005%, while for naphthalene in n-hexane it was 0.001%. Additionally, we explore more sensitive experiments where the (Δυ = 5) transition of the impurity is detected concurrently with the (Δυ = 6) transition of the solvent. This analytical method can also be adapted for use with saturated alcohols in solution contaminating hydrocarbon solvents. Full article

This study assesses the distribution of nutrients, trace elements, and heavy metals across different granulometric fractions of municipal solid waste (MSW) compost from three regions: Kaunas and Alytus (Lithuania) and Daugavpils (Latvia). Samples were collected from mechanical biological treatment plants (MBTPs) and fractionated into six different granulometric fractions (>5 mm, 5–2.5 mm, 2.5–1 mm, 1–0.5 mm, 0.5–0.2 mm, and <0.2 mm). Each fraction was subjected to physicochemical characterization. Macronutrients (Ca, K, Mg, P), trace elements (Al, As, Co, Fe, Mn, Mo), and heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) were analyzed using ICP-OES in triplicate. Results showed that essential nutrients and toxic metals were retained more in the finer fractions (<1 mm). In contrast, undesirable impurities, mainly glass, were retained in the coarse fractions across all the studied areas. All fractions in the compost samples of Kaunas, and coarse fractions (>5 mm, and 5–2.5 mm) of Alytus and Daugavpils are suitable to use as a soil amendment only if the undesirable impurities are removed to the acceptable limits in the coarse fractions. The fine fractions of Alytus have higher levels of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn), while Daugavpils showed higher levels of Cd, Cu, Ni, and Zn, exceeding the EU limits. Regarding physical fractionation, results showed that nutrients and heavy metals increased in the compost as particle size decreased. Our findings suggest that removing particle sizes < 1 mm and large impurities from the coarse fractions can enhance compost quality. Overall, particle-size fractionation can improve the consistency and safety of MBT-derived MSW compost for reuse in circular waste management systems. Full article

Indium is a strategically important metal, essential for the production of transparent conductive oxides, flat panel displays, thin-film photovoltaics, and advanced optoelectronic devices. Due to its limited natural abundance and its occurrence in trace amounts alongside other metals in both primary and secondary sources, the recovery of indium through efficient separation techniques has gained increasing attention. This review discusses three major separation strategies for indium recovery: solvent extraction, ion-exchange, and membrane processes, applied to both synthetic solutions and real leachates. D2EHPA has demonstrated its applicability as an effective agent for indium separation, not only in solvent extraction but also as an impregnating agent in polymer resins and membranes. While solvent extraction achieves high recovery rates, ion-exchange resins and membrane-based methods offer significant advantages in terms of reusability, reduced chemical consumption, and minimal environmental impact. The selective separation of indium from impurities such as Fe³⁺ and Sn²⁺ remains a key consideration, which can be addressed by optimizing feed solution conditions or adjusting the selective stripping stages. A comparative overview of these methods is provided, focusing on separation efficiency, operational conditions, and potential integration into close-loop systems. The article highlights recent innovations and outlines the challenges involved in achieving sustainable indium recovery, in line with circular economy principles. Full article

This paper presents a comprehensive characterization of bottom ash generated during biomass combustion in fluidized boilers, with a focus on its potential use in a circular economy. Two biomass bottom ash samples (BBA 1 and BBA 2) from commercial combined heat and power plants were tested. The scope of this study included the determination of chemical composition, phase composition, and leachability testing of selected impurities. The results showed that the bottom ashes tested are calcium silicate materials with varying proportions of calcium phases (anhydrite, portlandite, and calcite) and silica phases (quartz), depending on the type of biomass and combustion technology. Thermal analysis confirmed the presence of characteristic dehydration, decarbonation, and polymorphic transformations of quartz, with a low organic content. Leachability tests showed low mobility of most trace elements and heavy metals, with increased solubility of sulfates, chlorides, and alkali ions, typical for fluidized ash. The concentrations of As, Cd, Cr, Cu, Pb, Zn, and Hg in the eluates were low or below the limit of quantification, indicating the favorable chemical stability of the tested waste. The results obtained suggest that bottom ashes from biomass combustion in fluidized boilers may be a promising secondary raw material for engineering applications, especially in binding materials and bonded layers, and potentially also in selected agricultural applications, provided that the contents of sulfates, chlorides, and pH are controlled. Full article

Binder jet 3D printing combined with a low-temperature phase transformation process has emerged as a promising route for producing 3D-printed hydroxyapatite (3DPHA) scaffolds with controlled architecture for bone grafting applications. However, the toxicological profile of this unique binder jet-derived material has not yet been established. In this study, we conducted a comprehensive compositional and toxicological assessment of 3DPHA fabricated via the calcium sulfate transformation route. The material exhibited phase-pure hydroxyapatite (HA) with a Ca/P ratio consistent with non-stoichiometric HA and low levels of trace elemental impurities. In vitro assays revealed no cytotoxic, irritant, sensitizing, or mutagenic effects. This work provides a standardized toxicological and compositional safety validation of 3DPHA. By linking compositional purity to biological safety and demonstrating compliance with international benchmarks, this study establishes a regulatory foundation confirming that 3DPHA is chemically pure, biologically safe, and ready for clinical translation as a bone-graft material. Full article

The selective removal of trace heteroatomic contaminants from fuel remains a critical challenge for clean combustion and refinery upgrading, particularly due to the chemical stability and structural similarity of sulfur- and nitrogen-containing aromatics. Herein, a surface-engineered graphene oxide aerogel functionalized with cyclodextrin (β-CD-CONH-GO) is developed via covalent grafting to introduce well-defined host–guest recognition sites within a porous framework. Spectroscopic and microscopic characterizations confirm successful functionalization, preserved aerogel morphology, and accessible hybrid interfaces. The removal process for monocyclic, bicyclic, and tricyclic impurities is governed by synergistic molecular inclusion within the cyclodextrin cavity, interfacial hydrogen bonding, and secondary confinement provided by the aerogel porosity. Thus, the β-CD-CONH-GO exhibits efficient adsorption toward representative bicyclic impurities, and the removal performance follows the order of indole > quinoline > benzothiophene. Kinetic analysis demonstrates pseudo-second-order adsorption behavior, indicating chemisorption dominated by cooperative host–guest recognition and hydrogen bonding. It possesses removal selectivity even in mixed systems containing structurally similar aliphatic and aromatic competitors and maintains > 95% efficiency after five regeneration cycles via ethanol extraction, confirming superb durability. This study demonstrates a feasible pathway to design adsorbents for deep fuel refining and highlights cyclodextrin-based graphene hybrid aerogels as promising candidates for separations. Full article

As one of the key components in technetium-labeled radiopharmaceuticals, the quality of the dimercaptosuccinate (DMSA) plays a critical role in determining the safety and efficacy of the final drug product. However, due to its high polarity and susceptibility to oxidation, comprehensive characterization of the impurity profile of DMSA remains challenging. In this study, high-performance liquid chromatography and mass spectrometry were employed to achieve a systematic and thorough analysis of DMSA-related impurities. First, an HPLC-UV method was developed to enable baseline separation of DMSA and its impurities. Subsequently, a two-dimensional liquid chromatography–tandem mass spectrometry (2D-LC-MS/MS) approach was applied to identify six structurally diverse impurities present in DMSA. The developed HPLC method was rigorously validated and demonstrated to be sensitive, robust, and suitable for the accurate quantification and detection of trace impurities. Using the validated method, DMSA raw materials sourced from multiple manufacturers were analyzed, revealing significant variability in their impurity profiles. These findings underscore the importance of stringent quality control measures for DMSA in radiopharmaceutical manufacturing. This work not only establishes a reliable analytical framework for impurity profiling and structural elucidation of DMSA but also provides valuable insights for the development of quality control strategies and process optimization of radiopharmaceuticals. Full article

Baijiu, China’s traditional distilled spirit, is produced through solid-state fermentation and distillation of grains, resulting in a highly complex chemical and sensory profile. However, exogenous impurities introduced via raw materials, water, equipment, packaging, or the surrounding environment pose significant challenges to both safety and quality. These impurities, including heavy metals, plasticizers, pesticide residues, mycotoxins, environmental pollutants, and un-authorized food additives, are associated with neurotoxicity, carcinogenicity, endocrine disruption, and sensory defects. This narrative review synthesizes current knowledge on their sources, reported concentration ranges in Baijiu (generally at trace µg/kg–mg/kg levels), analytical detection methods with sub-mg/kg sensitivity, and control strategies for these substances. Regulatory frameworks, including China’s standards, are critically assessed, with emphasis on gaps such as the lack of explicit limits for certain classes of impurities. Case studies of contamination incidents are discussed to illustrate practical risks and monitoring gaps. Emerging trends, including low- and zero-alcohol Baijiu, are also considered in relation to changing impurity profiles and detection requirements. Recommendations include tightening regulatory limits, adopting portable and real-time detection technologies, and promoting the development of “pure Baijiu” that meets international safety and quality expectations. Future research priorities center on high-resolution mass spectrometry, advanced real-time monitoring, and eco-friendly analytical solutions, ensuring that Baijiu maintains both cultural heritage and global competitiveness. Full article

Isosorbide-based polycarbonate (PIC) shows promising applications in medical devices and food packaging, owing to its excellent thermal stability, biosafety, optical properties, and scratch resistance. However, trace impurities, especially formic acid in isosorbide (ISB), can significantly influence the performance of PIC. Crude ISB was purified via ion exchange resin. Furthermore, the chromatographic parameters and the adsorption kinetics of formic acid were investigated. The results show that adsorption of formic acid follows the pseudo-second-order kinetic model, suggesting that it is chemisorption. The performance of PIC synthesized from purified ISB has been improved significantly, exhibiting number-average molecular weight (M_n) of 53.9 kg/mol, elongation at break of 10.2%, and Young’s modulus of 1.84 GPa, along with notably enhanced thermal and optical properties. Full article

Current research on Daoist neidan (內丹, Internal Alchemy) has primarily focused on its philosophical frameworks, practical methods, and therapeutic benefits; however, systematic inquiry into the mechanisms of failure during practice remains limited. This study investigates the long-neglected yet pivotal phenomenon of zouhuo rumo (走火入魔, fire deviation and entry into demonic states) within Daoist cultivation, especially as it emerges in the context of dual cultivation of xing and ming (性命雙修). Through textual and hermeneutical analysis, this study traces the historical evolution, semantic transformation, and causal structure of the term, revealing its dual function as both a technical deviation and a religious warning. Findings indicate that zouhuo rumo arises from the interplay of impure self-refinement, loss of mental focus, improper fire phases (火候), and illusory disturbances, reflecting a profound psychosomatic imbalance rooted in the practitioner’s mind-nature (心性). Daoism interprets this state as mokao (魔考, demonic trials in Daoist cultivation), a transformative mechanism designed to refine inner alignment. On this basis, this study proposes a three-stage healing pathway—Spirit Preservation and Breath Stabilization (存神定息), Inner Vision and Self-Reflection (內觀返照), and Transformation of Form and Refinement of Essence (化形改質)—and constructs a Daoist cultural healing model that integrates moral cultivation, breath regulation, and introspection. This model provides a non-pathologizing cultural framework for enhancing psychological resilience, reconstructing meaning, and addressing contemporary spiritual and psychological crises. Full article

Awareness of cosmetic product safety has grown in recent years. Certain ingredients and impurities, including heavy metals, may pose health risks to consumers. Heavy metals can be present in cosmetics as either intentional ingredients or contaminants, making strict monitoring of these substances essential. This review assesses the toxicological implications of heavy metals in cosmetics, with a focus on advancements in analytical quantification methods, health risk assessment, and emerging non-animal-based approaches for evaluating toxicological profiles. Recent studies have detected traces of toxic metals, some exceeding permissible levels, in various cosmetic products, highlighting the need for ongoing monitoring programs to address heavy metal contamination. Additionally, the review emphasizes the importance of reliable and validated exposure assessment models and non-animal methodologies for determining systemic toxicity. Full article

In this study, a modified Curie–Weiss model was established for the magnetic susceptibility of high-purity molybdenum and Mo–La alloy powders. The elemental composition was analyzed by GDMS, and combined with the M–T and M–H data measured by SQUID, the temperature-independent contributions of weakly magnetic elements such as La and the paramagnetic contributions of impurity ions such as Fe, Co, and Ni were distinguished. Based on the parameters obtained from the nonlinear least squares fitting, the deviation between the magnetic susceptibility at room temperature calculated by the model and the experimental value was within 5%. The results show that this model can reasonably describe the influence of trace impurities on the magnetic susceptibility of the system and provides an effective method for the magnetic prediction of high-purity metal powders. Full article

Energy security is a growing societal and industrial concern that leads research and development toward more sustainable options. Biogas, a bio-alternative to conventional fuels, is a product generated from the anaerobic digestion of organic matter. This source of fuel production is more environmentally friendly compared to traditional fossil fuels, leading to a lower carbon footprint, higher air quality, and the promotion of a circular economy. Impurities of raw biogas, such as carbon dioxide, hydrogen sulfide, and other trace contaminants, make biogas conditioning necessary for most applications. In addition, biogas upgrading, technologies furthering biogas purity, is an important factor in the production of biomethane, a sustainable biofuel known more commonly as renewable natural gas (RNG). Diversifying fuel sources and providing energy sustainability while mitigating negative environmental effects makes RNG an attractive alternative to conventional natural gas. This document, Part I, provides an overview of current technologies related to biogas conditioning, such as sorption, oxidation, and biological treatments aimed at the removal of a wide variety of contaminants. Processes developed for biogas upgrading are also discussed, including physical/chemical absorption, pressure swing adsorption, and membrane separation. The focus of upgrading applies approaches in meeting a higher quality biofuel by further carbon dioxide exclusion to ease pipeline transport and increase combustion efficiency. These technologies present the core foundation of processes in the production of RNG; however, all face inherent challenges that deem further research and development a requirement for global adoption. The biggest challenges are either in the cost of reaching higher purities or the inability to do so without other operations. Thus, in conjunction with this document, emerging and developing technologies are provided in a separate analysis deemed Part II. Together, these documents offer a comprehensive understanding of current practices and growing technological developments. Full article