Machine learning-assisted fluorescence visualization for sequential quantitative detection of aluminum and fluoride ions.

The presence of aluminum (Al3+) and fluoride (F-) ions in the environment can be harmful to ecosystems and human health, highlighting the need for accurate and efficient monitoring. In this paper, an innovative approach is presented that leverages the power of machine learning to enhance the accuracy and efficiency of fluorescence-based detection for sequential quantitative analysis of aluminum (Al3+) and fluoride (F-) ions in aqueous solutions. The proposed method involves the synthesis of sulfur-functionalized carbon dots (C-dots) as fluorescence probes, with fluorescence enhancement upon interaction with Al3+ ions, achieving a detection limit of 4.2 nmol/L. Subsequently, in the presence of F- ions, fluorescence is quenched, with a detection limit of 47.6 nmol/L. The fingerprints of fluorescence images are extracted using a cross-platform computer vision library in Python, followed by data preprocessing. Subsequently, the fingerprint data is subjected to cluster analysis using the K-means model from machine learning, and the average Silhouette Coefficient indicates excellent model performance. Finally, a regression analysis based on the principal component analysis method is employed to achieve more precise quantitative analysis of aluminum and fluoride ions. The results demonstrate that the developed model excels in terms of accuracy and sensitivity. This groundbreaking model not only showcases exceptional performance but also addresses the urgent need for effective environmental monitoring and risk assessment, making it a valuable tool for safeguarding our ecosystems and public health.

Study on adsorption behavior of humic acid on aluminum in Enteromorpha prolifera.

High level of aluminum content in Enteromorpha prolifera posed a growing threat to both its growth and human health. This study focused on exploring the factors, impacts, and process of removing aluminum from Enteromorpha prolifera using humic acid. The results showed that under experimental conditions of 0.0330 g·L-1 humic acid concentration, pH 3.80, 34 °C, and a duration of 40 min, the removal rate was up to 80.18%. The levels of major flavor components, proteins, and amino acids in Enteromorpha prolifera increased significantly after treatment, while polysaccharides and trace elements like calcium and magnesium decreased significantly. Infrared spectroscopy demonstrated that the main functional groups involved in binding with Al3+ during humic acid adsorption were hydroxyl, carboxyl, phenol, and other oxygen-containing groups. The adsorption process of Al3+ by humic acid was a spontaneous phenomenon divided into three key stages: fast adsorption, slow adsorption, and adsorption equilibrium, which resulted from both physical and chemical adsorption effects. This study provided a safe and efficient method in algae metal removal.

Heterogeneous evolution and driving forces of multiple hazardous air pollutants and GHGs emissions from China's primary aluminum industry.

The booming of China's primary aluminum industry (PAI) brought substantial emissions of hazardous air pollutants (HAPs) and greenhouse gases (GHGs). By using life cycle assessment and bottom-up method, a comprehensive emission inventory for multiple typical HAPs and GHGs from China's PAI during 1990-2021 was developed and explored for the first time. Our results show that spatial-temporal emissions trends of HAPs and GHGs from PAI in China diverse significantly. The conventional atmospheric pollutants (including SO2, NOx and particulate matter (PM)), fluoride and per fluorinated compound (PFCs) had been effectively suppressed since 2007 due to the implementation of various environmental policies; while, emissions of CO, VOCs, CH4, heavy metals and CO2 had increased at different rates unexpectedly. From the spatial distribution perspective, Henan, Shanxi, Guizhou, Guangxi and Shandong dominated the emissions of PAI in China, but with consumption expansion and environmental constrains, PAI plants start to expand to northwest and southwest areas where are richer in sufficient and cheaper power resources, thus bring significant emission increasing there, particular for conventional atmospheric pollutants in northwest and CO and VOCs in southwest China. By underlying driving forces of PAI emissions, results show that end-of-pipe control measures at various stages have played different roles to reduce emissions of the concerned species at each period, but its reduction effect diminished gradually. Future reduction should seek underlying changes in production technology and energy system. Under constrains of environmental regulation and resource endowment, promoting circular economic development for PAI would be a key strategy to reduce HAPs and GHGs emissions simultaneously in PAI.

Toward a better understanding of polymeric aluminum-modified attapulgite for the efficient removal of low phosphorus concentration.

Attapulgite (ATP) is a biocompatible clay mineral that efficiently absorbs water. It is widely used in water treatment due to its environmental friendliness and cost-effectiveness. This study aimed to develop a volume-expansion structure-based attapulgite flocculant (VES-ATP) using aluminum salt and attapulgite (ATP) under alkaline conditions, specifically for the treatment of water containing low levels of phosphorus. The VES-ATP was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The removal of phosphorus by the VES-ATP was conducted by varying the mass ratio of Al to attapulgite (denoted as RmAl/mATP), ATP dosage, and pH. The results showed that the VES-ATP had a good expansion and dispersibility in the presence of alkalized aluminum species. The basicity as the molar ratio of OH to Al (0.8 or 1.6) determined the expansion feasibility, and the coverage degree of Al onto ATP, as indicated by the mass ratio of Al to attapulgite (denoted as RmAl/mATP), determined Al flocculation efficiency. Higher values such as RmAl/mATP = 4:1 and 2:1 may result in a better flocculation. Low phosphorus treatment was successfully achieved through Al flocculation and ATP adsorption, including complexation, hydrogen bonding, and electrostatic attraction. As expected, the VES-ATP generated larger size flocs with a bigger fractal dimension than that with the sole Al flocculation. As a result, the total phosphorus could be reduced to the level below 5 µg/L. It is more efficient in the pH range of 5-9. Overall, the coupling of aluminum and attapulgite has significantly enhanced both purification capabilities of phosphorus. PRACTITIONER POINTS: Polymeric aluminum-modified attapulgite was efficient for removal of low phosphorus concentration. Phosphorus concentrations can be reduced to below 5 µg/L. Polymeric aluminum and attapulgite are both safe, and this technology is suitable for water treatment.

Aluminum-induced oxidative stress promotes changes in the structure of the gut microbiota and liver deficiency.

As a low-toxicity metal, aluminum has garnered increasing attention in relation to its impact on the human body; however, the specific mechanism of action remains unclear. To bridge this knowledge gap and facilitate practical applications, this study took 8-week-old ICR mice as the research object to study the effects of dietary addition of aluminum potassium sulfate on intestinal flora structure and liver. As the concentration of aluminum increased, it inhibited mice weight growth rate and significantly altered the composition of white blood cells in their bloodstream. Histological examination revealed liver inflammation through HE staining sections. The oxidative stress markers MDA increased, GSH-PX and CAT decreased significantly. And liver function index MAO increased, TC and ALP decreased first and then increased. Moreover, there was a significant increase in pro-inflammatory factor TNF-α content. Further 16S rRNA sequencing analysis demonstrated substantial changes in both composition and structure of mouse intestinal microbiota induced by aluminum exposure; microbial phenotype prediction indicated that aluminum-induced oxidative stress promoted an increase in abundance of oxidation-resistant microbial types. Alterations in gut flora structure also influenced the liver via the gut-liver axis. These findings lay a foundation for further research on the regulation and interaction of aluminum on intestinal flora.

Facile Determination of Aluminum Content in Industrial Brine by Investigating the Effects of Buffer Systems.

The aluminum content of concentrated (27 wt%) sodium chloride solutions could be crucial for large-scale chlor-alkali-based industries applying membrane cell electrolysis. Thus, a facile method which enables a fast and reliable protocol to determine the Al content of these solutions on ppb scale in industrial environments is fundamentally important. It was demonstrated that the increased sensitivity of colorful Al-ECR (eriochrome cyanine R) complex by the use of a cationic surfactant and specific biological buffers could effectively indicate the Al content in an extended pH interval of a concentrated saline medium under industrial conditions. The dependence of the analytical protocol on pH, temperature, time, wavelength, and the salinity of the medium was investigated. It was shown that the absorbance-based measurements of the solution should be performed at least 2-4 h after its preparation. By applying the selected two Good's buffers (HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, MOPS: 3-(N-morpholino)-propanesulfonic acid) and Tris (tris(hydroxymethyl)aminomethane), 32.8-38.1 % increase in the sensitivity was achieved for saturated NaCl solutions. Moreover, the limits of detection and quantification (LOD, LOQ) were also lowered by 19.0-29.8 %, and the salinity dependence of the calibration was also reduced.

Evaluation of Aluminum and Magnesium Absorption Following the Oral Administration of an Antacid Suspension Containing Magaldrate in Healthy Women Under Fed Conditions.

INTRODUCTION: Antacids are commonly used during pregnancy, and they are approved for the relief of symptoms of gastroesophageal reflux disease (GERD) during pregnancy. However, there are no reports of the quantification of the absorption of aluminum and magnesium in the antacid magaldrate in women. The aim of this study was to quantify the rate and magnitude of absorption of aluminum and magnesium in magaldrate. METHODS: An open-label, controlled, randomized, one-treatment study with a two-group design was conducted in healthy women in a fed state. The volunteers had a standard breakfast, and 30 min later, they were given a single-medication sachet containing 500 mg of sodium alginate, 267 mg of sodium bicarbonate, 800 mg of magaldrate, and 120 mg of simethicone (group A, n = 8) or no medication (group B, n = 2). Blood samples were obtained 36 h before and up to 12 h after antacid administration. The method used for quantification was inductively coupled plasma-mass spectrometry. RESULTS: There was no absorption of aluminum in any of the blood samples from the healthy volunteers who received the drug or in those from the control group. Magnesium was detected at normal concentrations. CONCLUSION: These findings suggest that the use of this antacid is safe and without risk in healthy women, including pregnant women. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov registration: NCT06367452.

Enhancing water heater efficiency with aluminum and zinc-coated steel systems for energy solutions.

Solar collector plates are integral components for efficient solar heat transfer. While various metallic materials can serve as collector plates, aluminum stands out as a commonly employed choice with thermal conductivity comparable to copper and zinc. The material's thermal conductivity significantly impacts the heat transfer efficiency from sunlight to the collector. Moreover, the surface configuration of the plate is a crucial factor affecting solar heat absorption. This study investigates the utilization of corrugated collector plates made from two materials, aluminum and zinc-coated steel. The solar collector testing phase covers the dry and rainy seasons in Indonesia, thereby providing a comprehensive evaluation in various weather conditions. There are two stages of solar collector testing, namely testing before it is used to heat water and testing to heat water. Radiation data show seasonal variations, with higher radiation observed in the dry season. Evaluation of the performance of the solar collector before being used to heat water resulted in an average efficiency of 41.45 % for aluminum and 33.94 % for zinc-coated steel. Meanwhile, evaluation of the performance of solar collectors used to heat water produces an average efficiency of 20.40 % for aluminum and 10.47 % for zinc-coated steel. Corrugated aluminum solar collectors exhibited promising absorber potential, while zinc-coated steel demonstrated economic viability due to its lower cost compared to aluminum. The research underscores the potential applicability of solar collectors made from both materials throughout different seasons.

Physiological and comprehensive transcriptome analysis reveals distinct regulatory mechanisms for aluminum tolerance of Trifolium repens.

It is estimated that up to 50 % of arable lands worldwide are acidic, and most crops are severely inhibited due to the high active aluminum (Al). Trifolium repens is an excellent legume forage with a certain acid tolerance, although it is affected by Al toxicity in acidic soil. In this study, physiological and transcriptomic responses of different white clover varieties were analyzed when exposed to a high-level of Al stress. The results revealed that Trifolium repens had a high level of Al toxicity tolerance, and accumulated nearly 70 % of Al3+ in its roots. Al toxicity significantly inhibited the root length and root activity, decreased the chlorophyll (Chl) content and photosynthetic pigments, while significantly increased the intercellular CO2 concentration (Ci). The content of malondialdehyde (MDA), electrolyte leakage (EL), proline and reactive oxygen species (ROS) were significantly accumulated under Al stress. Furthermore, a total of 27,480 differentially expressed genes (DEGs) were identified after the treatment. Gene ontology (GO) and Kyoto encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that most Al-responsive genes enriched to chloroplast thylakoid membrane, chloroplast stroma and photosynthesis in Haifa leaf while in MAG leaf highly enriched in response to regulation of defense response, which could induce the different tolerance of the two cultivars to Al stress. Besides, pectin methylesterase (PME), glycosyl transferases (GT1) and chalcone synthase genes associated with cell wall biosynthesis may improve the Al accumulation and enhance tolerance of Al toxicity. The results established here would help to understand the morphological structure, physiological and biochemical response, and molecular mechanism of white clover under Al tolerance.

Heterostructure Engineering for Aluminum-Ion Batteries: Mechanism, Challenge, and Perspective.

Benefiting from high volumetric capacity, environmental friendliness, and high safety, aluminum-ion batteries (AIBs) are considered to be promising battery system among emerging electrochemical energy storage technologies. As an important component of AIBs, the cathode material is crucial to decide the energy density and cycle life of AIBs. However, single-component cathode materials are unable to achieve a balance between cycling stability and rate performance. In recent years, research on heterostructure cathode materials has gained significant attention in AIBs. By harnessing the synergistic effects of heterostructure, the shortcomings of individual materials can be overcome, contributing to improved conductivity and structural stability. This review offers a detailed insight into the Al-storage mechanism of heterostructure cathodes, and provides an overview of the current research progresses on heterostructure cathode materials for AIBs. Starting from the relationship between the microstructure and electrochemical performance of heterostructure materials, the different structure design strategies are elaborated. Besides, the challenges faced by heterostructure are summarized, and their potential impact on the future of the energy storage industry is anticipated. This review provides the guidelines for the future research of heterostructure as cathode materials for AIBs.

Coagulation performance and mechanism of different novel covalently bonded organic silicon-aluminum/iron composite coagulant for As(V) removal from water: The role of hydrolysate species and the effect of coexisting microplastics.

Arsenate [As(V)] pollution is a challenge for water treatment, and the effect of coexisting microplastics (MPs) on As(V) removal is still not clear. In this study, series novel covalently bonded organic silicon-aluminum/iron composite coagulants (CSA/F) with different Al/Fe molar ratios were prepared for enhancing As(V) removal. The effect mechanism of MPs (PS MPs and PS-COOH MPs) on As(V) removal by using CSAF coagulation was analyzed. CSAF and CSF showed significantly better As(V) removal performance than other coagulants under the same conditions, especially CSF, more than 90 % As(V) removal was achieved at dosage of 20 mg/L and pH of 4.0-8.0. Interestingly, the introduction of silane coupling agent and the increase of Fe content in CSA/F changed the Al/Fe species distribution. Charge neutralization dominant in As(V) removal by using CSA, whereas adsorption and net sweeping contributed to As(V) coagulation by using CSAF and CSF with higher iron proportion at neutral pH. 3 µm MPs were removed by net sweeping of amorphous Al/Fe hydroxides, while 26 µm MPs were charge-neutralized or surface adsorbed by coagulant hydrolysates. The aliphatic C-H and -COOH functional groups of MPs were the main sites of hydrogen bonding adsorption with the hydroxyl groups of coagulant hydrolysates. This study is conducive to mitigating the environmental toxicity of arsenic and provides new insights into the interaction mechanism between composite pollutants and coagulants in waters.

LncRNA 51A: A promising diagnostic biomarker for assessing cognitive decline in occupationally exposed aluminum workers.

OBJECTIVE: To assess the diagnostic utility of lncRNA 51 A in detecting cognitive decline among aluminum-exposed workers occupationally. METHODS: 921 male workers from an aluminum manufacturing facility underwent cognitive assessments, measurement of plasma aluminum levels and quantification of lncRNA 51 A levels. Receiver Operating Characteristic (ROC) curves were constructed to assess the diagnostic potential of lncRNA 51 A. Bayesian network model was utilized to predict the likelihood of cognitive decline among the study population. RESULTS: Significant differences in lncRNA 51 A levels, plasma aluminum concentration and MMSE scores were observed between cognitive normal and decline groups. The lncRNA 51 A expression was negatively correlated with MMSE scores. The area under the curve (AUC) was 0.894, with 89.3 % sensitivity and 73.9 % specificity. The Bayesian network model indicated varying probabilities of cognitive decline based on lncRNA 51 A expression levels. CONCLUSION: Plasma lncRNA 51 A shows potential as an excellent biomarker for cognitive decline diagnosis in aluminum-exposed workers.

Three birds with one stone: Sewage sludge deep-drying in 1 hour using secondary aluminum ash to fabricate bricks.

Due to the high moisture, strong hydrophilicity, and hard compressibility of sewage sludge (SS), it is difficult to realize the high-efficiency drying. Herein, a novel SS drying technology was developed to quickly and deeply reduce the moisture of SS from 75.6% to 38.5% in 1 h. During the process, secondary aluminum ash (SAA), a solid waste, was added to SS and acted as skeletons to form plenty of channels. Subsequently, NaOH was added and reacted with SAA to produce a lot of heat, resulting in a rapid temperature rise of the system from 20 to 105°C in 60 s. The heat could effectively remove water from these channels, which could be proved by the T1-T2 maps of in-site Low-Field 1H nuclear magnetic resonance. In addition, the extracellular polymeric substances were decomposed by SAA/NaOH successfully, and thus the SS became hydrophobic, favoring the drying. Finally, the dried SS could be used to fabricate unburned bricks. Thus, this work provides a promising method to realize the rapid SS deep drying and high-efficiency utilization of SAA and dried SS.

Assessment of the role of N-terminal pro-B-type natriuretic peptide as a predictive biomarker of mortality in acute aluminum phosphide poisoning.

BACKGROUND: In Egypt, aluminum phosphide (ALP) is a known lethal poison due to its cardiotoxicity. This study aimed to evaluate the predictive ability of N-terminal pro-B-type natriuretic peptide (NT-proBNP) for mortality in ALP-poisoned patients. METHODS: This prospective study was conducted on patients with ALP poisoning admitted to the Poison Control Center Ain Shams University Hospitals between July and December 2022. Upon admission, all patients were followed up and had their levels of NT-proBNP, troponin I (cTnI), and creatine kinase myocardial band (CK-MB) analyzed. RESULTS: Thirty patients were enrolled in the study and were divided into survivors and non-survivors. The initial NT-proBNP levels were significantly higher among non-survivors in contrast to the initial cTnI and CK-MB levels. The study identified that the best cutoff point of NT-proBNP for predicting mortality was ≥72 pg/ml, with AUC (0.869). CONCLUSION: It can be concluded that NT-proBNP can serve as an early predictor of mortality in ALP poisoning.

Bone aluminum accumulation in the current era / Acúmulo de alumínio no tecido ósseo na era atual

In the last few years, evidence from the Brazilian Registry of Bone Biopsy (REBRABO) has pointed out a high incidence of aluminum (Al) accumulation in the bones of patients with CKD under dialysis. This surprising finding does not appear to be merely a passive metal accumulation, as prospective data from REBRABO suggest that the presence of Al in bone may be independently associated with major adverse cardiovascular events. This information contrasts with the perception of epidemiologic control of this condition around the world. In this opinion paper, we discussed why the diagnosis of Al accumulation in bone is not reported in other parts of the world. We also discuss a range of possibilities to understand why bone Al accumulation still occurs, not as a classical syndrome with systemic signs of intoxication, as occurred it has in the past.

Nos últimos anos, evidências do Registro Brasileiro de Biópsia óssea (REBRABO) apontaram uma alta incidência de intoxicação por alumínio (Al) no tecido ósseo de pacientes com DRC em diálise. Essa surpreendente informação parece representar não apenas um acúmulo passivo deste metal, visto que dados prospectivos do REBRABO sugerem que a presença de Al no tecido ósseo pode estar independentemente relacionada a eventos cardiovasculares adversos maiores. Essas informações contrastam com a percepção mundial do controle epidemiológico dessa condição. Neste artigo de opinião, discutimos por que o diagnóstico de acúmulo ósseo de Al não é relatado em outras partes do mundo, e também discutimos uma gama de possibilidades para entender por que nós acreditamos que o acúmulo de Al no tecido ósseo ainda ocorre, não como se apresentava no passado, ou seja, como uma síndrome com sinais e sintomas sistêmicos de intoxicação.

Manganese-Modified Aluminum Adjuvant Enhances both Humoral and Cellular Immune Responses.

Aluminum adjuvants remain the most commonly used vaccine adjuvants. Being rather effective in triggering humoral immunity, however, aluminum adjuvants usually show limited abilities in activating cellular immunities. Herein, by adding manganese ions during the preparation of aluminum adjuvant, a manganese-modified aluminum (Mn-Al) adjuvant is obtained, which can effectively stimulate both humoral and cellular immune responses. Such Mn-Al adjuvant can enhance antigen adsorption and promote antigen internalization by dendritic cells (DCs). Subsequently, the released Mn2+ can activate the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway to further promote DC activation. When combines with the model antigen ovalbumin (OVA), the Mn-Al-adjuvantes vaccine can induce high levels of antigen-specific antibody titers and high proportions of antigen-specific cytotoxic T cells in vivo. Moreover, the Mn-Al-adjuvanted vaccine elicited stronger antigen-specific humoral and cellular immune responses than high-dose of the aluminum-based adjuvant. Additionally, immunization of mice with OVA in the presence of the Mn-Al adjuvant significantly inhibited the growth of B16-OVA tumors. Furthermore, when formulated with human papillomavirus antigens, Mn-Al-adjuvanted vaccines show better in vivo vaccination performance than aluminum-adjuvanted vaccines. Therefore, the manganese-modified aluminum adjuvant may thus become a new vaccine adjuvant with the potential to replace conventional aluminum adjuvants.

Research Advances of Cathode Materials for Rechargeable Aluminum Batteries.

Rechargeable aluminum ion batteries (AIBs) have recently gained widespread research concern as energy storage technologies because of their advantages of being safe, economical, environmentally friendly, sustainable, and displaying high performance. Nevertheless, the intense Coulombic interactions between the Al3+ ions with high charge density and the lattice of the electrode body lead to poor cathode kinetics and limited cycle life in AIBs. This paper reviews the recent advances in the cathode design of AIBs to gain a comprehensive understanding of the opportunities and challenges presented by current AIBs. In addition, the advantages, limitations, and possible solutions of each cathode material are discussed. Finally, the future development prospect of the cathode materials is presented.

Ferroelectric Aluminum Scandium Nitride Transistors with Intrinsic Switching Characteristics and Artificial Synaptic Functions for Neuromorphic Computing.

Aluminum Scandium Nitride (Al1-xScxN) has received attention for its exceptional ferroelectric properties, whereas the fundamental mechanism determining its dynamic response and reliability remains elusive. In this work, an unreported nucleation-based polarization switching mechanism in Al0.7Sc0.3N (AlScN) is unveiled, driven by its intrinsic ferroelectricity rooted in the ionic displacement. Fast polarization switching, characterized by a remarkably low characteristic time of 0.00183 ps, is captured, and effectively simulated using a nucleation-limited switching (NLS) model, where the profound effect of defects on the nucleation and domain propagation is systematically studied. These findings are further integrated into Monte Carlo simulations to unravel the influence of the activation energy for ferroelectric switching on the distributions of switching thresholds. The long-term reliability of devices is also confirmed by time-dependent dielectric breakdown (TDDB) measurements, and the effect of thickness scaling is discussed. Ferroelectric field-effect transistors (FeFETs) are demonstrated through the integration of AlScN and 2D MoS2 channel, where biological synaptic functions can be emulated with optimized operation voltage. The artificial neural network built from AlScN-based FeFETs achieves 93.8% recognition accuracy of handwritten digits, demonstrating the potential of ferroelectric AlScN in future neuromorphic computing applications.

A Brief Review of Effects of Aluminum on Marine Diatoms.

Aluminum (Al) is the most abundant metal element in the Earth's crust, yet it is present in trace levels in seawater. Growing evidence suggests potential effects of Al on the biogeochemical cycles of carbon (C) and silicon (Si) in the marine environment. By accumulation, sinking, and deposition, diatoms play a center role in coupling these three elements' biocycles in the oceans. However, it is still a challenge to elucidate the behaviors of diatoms influenced by Al. Our review aims to present the current knowledge of Al biogeochemistry in marine environment and its impact on marine phytoplankton, with a focus on how Al influences diatoms. Previous researches indicate that Al can promote the growth of diatoms, and diatoms have the ability to incorporate Al into their frustules. Given this, we paid particular attention on the interaction between Al and diatom frustules, and the influences of Al on the physiology and ecology of diatoms. Furthermore, it is suggested that Al alters the accumulation of other nutrients such as nitrogen, phosphorus and iron in diatoms; the subsequent responses of diatoms are also discussed. The objective of this review is to address the potential roles of Al in diatoms and offer insights into the possible biogeochemistry implications.

Synthesis and preclinical evaluation of [18F]AlF-NODA-MP-C6-CTHRSSVVC as a PET tracer for CD163-positive tumor-infiltrating macrophages.

Positron emission tomography (PET) can provide information about tumor-associated macrophage (TAM) infiltration, as long as a suitable tracer is available. This study aimed to evaluate the radiolabeled peptide [18F]AlF-NODA-MP-C6-CTHRSSVVC as a potential PET tracer for imaging of the CD163 receptor, which is expressed on M2-type tumor-associated macrophages. The conjugated peptide NODA-MP-C6-CTHRSSVVC was labeled with aluminum [18F]fluoride. Tracer binding and its biodistribution were evaluated in an in vitro binding assay and in healthy BALB/c mice, respectively. In addition, different treatments with cyclophosphamide in tumor-bearing mice were used to assess whether the tracer could detect differences in CD163 expression caused by differential TAM infiltration. After 7 days of treatment, animals were injected with [18F]AlF-NODA-MP-C6-CTHRSSVVC, and a 60-min dynamic PET scan was performed, followed by an ex vivo biodistribution study. [18F]AlF-NODA-MP-C6-CTHRSSVVC was prepared in 23 ± 6 % radiochemical yield and showed approximately 50 % of specific receptor-mediated binding in an in vitro binding assay on human CD163-expressing tissue homogenates. No CD163-mediated binding of [18F]AlF-NODA-MP-C6-CTHRSSVVC was detected by PET under normal physiological conditions in healthy BALB/c mice. On the other hand, CD163-positive xenograft tumors were clearly visualized with PET and a positive correlation was found between CD163 levels and the [18F]AlF-NODA-MP-C6-CTHRSSVVC tumor-to-muscle ratio (TMR) obtained from the PET images (Pearson r = 0.76, p = 0.002). No significant differences in the CD163 protein level and in the tracer uptake between treatment groups were found in the tumors. Taken together, [18F]AlF-NODA-MP-C6-CTHRSSVVC appears a promising candidate PET tracer for M2-type TAM, as it binds specifically to CD163 in vitro and its tumor uptake correlates well with CD163 expression in vivo.