Advances in heavy alkaline earth chemistry provide insight into complexation of weakly polarizing Ra2+, Ba2+, and Sr2+ cations.

Numerous technologies-with catalytic, therapeutic, and diagnostic applications-would benefit from improved chelation strategies for heavy alkaline earth elements: Ra2+, Ba2+, and Sr2+. Unfortunately, chelating these metals is challenging because of their large size and weak polarizing power. We found 18-crown-6-tetracarboxylic acid (H4COCO) bound Ra2+, Ba2+, and Sr2+ to form M(HxCOCO)x-2. Upon isolating radioactive 223Ra from its parent radionuclides (227Ac and 227Th), 223Ra2+ reacted with the fully deprotonated COCO4- chelator to generate Ra(COCO)2-(aq) (log KRa(COCO)2- = 5.97 ± 0.01), a rare example of a molecular radium complex. Comparative analyses with Sr2+ and Ba2+ congeners informed on what attributes engendered success in heavy alkaline earth complexation. Chelators with high negative charge [-4 for Ra(COCO)2-(aq)] and many donor atoms [≥11 in Ra(COCO)2-(aq)] provided a framework for stable complex formation. These conditions achieved steric saturation and overcame the weak polarization powers associated with these large dicationic metals.

Rapid inverse radiative transfer solver for multiparameter spectrophotometry without integrating sphere.

Significance: Multiparameter spectrophotometry (MPS) provides a powerful tool for accurate characterization of turbid materials in applications such as analysis of material compositions, assay of biological tissues for clinical diagnosis and food safety monitoring. Aim: This work is aimed at development and validation of a rapid inverse solver based on a particle swarm optimization (PSO) algorithm to retrieve the radiative transfer (RT) parameters of absorption coefficient, scattering coefficient and anisotropy factor of a turbid sample. Approach: Monte Carlo (MC) simulations were performed to obtain calculated signals for comparison to the measured ones of diffuse reflectance, diffuse transmittance and forward transmittance. An objective function has been derived and combined with the PSO algorithm to iterate MC simulations for MPS. Results: We have shown that the objective function can significantly reduce the variance in calculated signals by local averaging of an inverse squared error sum function between measured and calculated signals in RT parameter space. For validation of the new objective function for PSO based inverse solver, the RT parameters of 20% Intralipid solutions have been determined from 520 to 1000 nm which took about 2.7 minutes on average to complete signal measurement and inverse calculation per wavelength. Conclusion: The rapid solver enables MPS to be translated into easy-to-use and cost-effective instruments without integrating sphere for material characterization by separating and revealing compositional profiles at the molecular and particulate scales.

Dopamine, Norepinephrine and Serotonin Participate Differently in Methylphenidate Action in Concomitant Behavioral and Ventral Tegmental Area, Locus Coeruleus and Dorsal Raphe Neuronal Study in Young Rats.

Methylphenidate (MPD), known as Ritalin, is a psychostimulant used to treat children, adults, and the elderly. MPD exerts its effects through increasing concentrations of dopamine (DA), norepinephrine (NE), and serotonin (5-HT) in the synaptic cleft. Concomitant behavioral and neuronal recording from the ventral tegmental area (VTA), locus coeruleus (LC), and from the dorsal raphe (DR) nucleus, which are the sources of DA, NE, and 5-HT to the mesocorticolimbic circuit, were investigated following acute and repetitive (chronic) saline, 0.6, 2.5, or 10.0 mg/kg MPD. Animals received daily saline or MPD administration on experimental days 1 to 6 (ED1-6), followed by a 3-day washout period and MPD rechallenge on ED10. Each chronic MPD dose elicits behavioral sensitization in some animals while inducing behavioral tolerance in others. The uniqueness of this study is in the evaluation of neuronal activity based on the behavioral response to chronic MPD. Neuronal excitation was observed mainly in brain areas of animals exhibiting behavioral sensitization, while neuronal attenuation following chronic MPD was observed in animals expressing behavioral tolerance. Different ratios of excitatory/inhibitory neuronal responses were obtained from the VTA, LC, or DR following chronic MPD. Thus, each brain area responds differently to each MPD dose used, suggesting that DA, NE, and 5-HT in the VTA, LC, and DR exert different effects.

Complex Three-Dimensional Microscale Structures for Quantum Sensing Applications.

We present a novel method for fabricating highly customizable three-dimensional structures hosting quantum sensors based on nitrogen vacancy (NV) centers using two-photon polymerization. This approach overcomes challenges associated with structuring traditional single-crystal quantum sensing platforms and enables the creation of complex, fully three-dimensional, sensor assemblies with submicroscale resolutions (down to 400 nm) and large fields of view (>1 mm). By embedding NV center-containing nanoparticles in exemplary structures, we demonstrate high sensitivity optical sensing of temperature and magnetic fields at the microscale. Our work showcases the potential for integrating quantum sensors with advanced manufacturing techniques, facilitating the incorporation of sensors into existing microfluidic and electronic platforms, and opening new avenues for widespread utilization of quantum sensors in various applications.

Alterations in Growth Habit to Channel End-of-Season Perennial Reserves towards Increased Yield and Reduced Regrowth after Defoliation in Upland Cotton (Gossypium hirsutum L.).

Cotton (Gossypium spp.) is the primary source of natural textile fiber in the U.S. and a major crop in the Southeastern U.S. Despite constant efforts to increase the cotton fiber yield, the yield gain has stagnated. Therefore, we undertook a novel approach to improve the cotton fiber yield by altering its growth habit from perennial to annual. In this effort, we identified genotypes with high-expression alleles of five floral induction and meristem identity genes (FT, SOC1, FUL, LFY, and AP1) from an Upland cotton mini-core collection and crossed them in various combinations to develop cotton lines with annual growth habit, optimal flowering time, and enhanced productivity. To facilitate the characterization of genotypes with the desired combinations of stacked alleles, we identified molecular markers associated with the gene expression traits via genome-wide association analysis using a 63 K SNP Array. Over 14,500 SNPs showed polymorphism and were used for association analysis. A total of 396 markers showed associations with expression traits. Of these 396 markers, 159 were mapped to genes, 50 to untranslated regions, and 187 to random genomic regions. Biased genomic distribution of associated markers was observed where more trait-associated markers mapped to the cotton D sub-genome. Many quantitative trait loci coincided at specific genomic regions. This observation has implications as these traits could be bred together. The analysis also allowed the identification of candidate regulators of the expression patterns of these floral induction and meristem identity genes whose functions will be validated.

Changes in antibacterial activity, colour, and hydrogen peroxide content of Western Australian Jarrah and Marri honeys after storage at different temperatures over time.

AIMS: This study aimed to evaluate the effects of storage and different temperatures on the antibacterial activity and physicochemical characteristics of several types of honey. METHODS AND RESULTS: Honeys stored for 16 weeks at 37 and 45°C showed significant declines in antibacterial activity determined by minimum inhibitory concentrations, the loss of hydrogen peroxide, decreases in honey pH, and increases in honey colour, with changes most pronounced at 45°C. In contrast, honeys stored for 16 weeks at ambient (∼22°C) and cold (4, -20, and -80°C) temperatures showed only minor changes. In a second set of 12 honeys stored for 16-32 months at ambient temperature and then 4°C, honeys showed minor changes in antibacterial activity, increases in colour, and decreases in pH. For a third set of 17 honeys stored for five years at ambient temperature, the honeys showed almost complete loss of hydrogen peroxide and were all significantly darker in colour, but showed varied changes in antibacterial activity. CONCLUSIONS: Heat was detrimental to the antibacterial activity of honeys, as was long-term storage at ambient temperatures for some honeys but not others.

Methylphenidate induces a different response in the dorsal raphe as compared to ventral tegmental area and locus coeruleus: behavioral and concomitant neuronal recordings in adult rats.

Methylphenidate (MPD) is a psychostimulant used to treat attention deficit hyperactivity disorder. MPD exerts its neurocognitive effects through increasing concentrations of dopamine (DA), norepinephrine (NE), and serotonin (5-HT) in the neuronal synapse. This study recorded from adult freely behaving rats a total of 1170 neurons, 403 from the ventral tegmental area (VTA), 409 from locus coeruleus (LC), and 356 from dorsal raphe (DR) nucleus, which are the main sources of DA, NE, and 5-HT to the mesocorticolimbic circuitry, respectively. Electrophysiological and behavioral activities were recorded simultaneously following acute and repetitive (chronic) saline or 0.6, 2.5, or 10.0 mg/kg MPD. The uniqueness of this study is the evaluation of neuronal activity based on the behavioral response to chronic MPD. Animals received daily saline or MPD administration on experimental days 1-6 (ED1-6), followed by a 3-day wash-out period, and then MPD rechallenge on ED10. Each chronic MPD dose elicits behavioral sensitization in some animals, while in others, behavioral tolerance. Neuronal excitation following chronic MPD was observed in brains areas of animals exhibiting behavioral sensitization, while neuronal attenuation following chronic MPD was observed in those animals expressing behavioral tolerance. DR neuronal activity was most affected in response to acute and chronic MPD administration and responded differently compared to the neurons recorded from VTA and LC neurons at all doses. This suggests that although not directly related, DR and 5-HT are involved in the acute and chronic effects of MPD in adult rats, but exhibit a different role in response to MPD.

Structure and Dynamics of NaCl/KCl/CaCl2-EuCln (n = 2, 3) Molten Salts.

Modern molten salt reactor design and the techniques of electrorefining spent nuclear fuels require a better understanding of the chemical and physical behavior of lanthanide/actinide ions with different oxidation states dissolved in various solvent salts. The molecular structures and dynamics that are driven by the short-range interactions between solute cations and anions and long-range solute and solvent cations are still unclear. In order to study the structural change of solute cations caused by different solvent salts, we performed first-principles molecular dynamics simulations in molten salts and extended X-ray absorption fine structure (EXAFS) measurements for the cooled molten salt samples to identify the local coordination environment of Eu2+ and Eu3+ ions in CaCl2, NaCl, and KCl. The simulations reveal that with the increasing polarizing the outer sphere cations from K+ to Na+ to Ca2+, the coordination number (CN) of Cl- in the first solvation shell increases from 5.6 (Eu2+) and 5.9 (Eu3+) in KCl to 6.9 (Eu2+) and 7.0 (Eu3+) in CaCl2. This coordination change is validated by the EXAFS measurements, in which the CN of Cl- around Eu increases from 5 in KCl to 7 in CaCl2. Our simulation shows that the fewer Cl- ions coordinated to Eu leads to a more rigid first coordination shell with longer lifetime. Furthermore, the diffusivities of Eu2+/Eu3+ are related to the rigidity of their first coordination shell of Cl-: the more rigid the first coordination shell is, the slower the solute cations diffuse.

Dynamics of oral microbiome acquisition in healthy infants: A pilot study.

Objectives: The human oral microbiota is one of the most complex bacterial communities in the human body. However, how newborns initially acquire these bacteria remains largely unknown. In this study, we examined the dynamics of oral microbial communities in healthy infants and investigated the influence of the maternal oral microbiota on the acquisition of the infant's oral microbiota. We hypothesized that the infant oral microbial diversity increases with age. Methods: One hundred and sixteen whole-salivary samples were collected from 32 healthy infants and their biological mothers during postpartum and 9- and 15-month well-infant visits. Bacterial genomic DNA was extracted and sequenced by Human Oral Microbe Identification using Next Generation Sequencing (HOMINGS) methods. The Shannon index was used to measure the microbial diversity of the infant-mother dyads (alpha diversity). The microbial diversity between the mother-infant dyads (beta-diversity) was calculated using the weighted non-phylogenetic Bray-Curtis distance in QIIME 1.9.1. Core microbiome analysis was performed using MicrobiomeAnalyst software. Linear discriminant analysis coupled with effect size analysis was used to identify differentially abundant features between mother and infant dyads. Results: A total of 6,870,571 16S rRNA reads were generated from paired mother-infant saliva samples. Overall, oral microbial profiles significantly differed between the mother and infant groups (p < 0.001). The diversity of the salivary microbiomes in the infants increased in an age-dependent manner, whereas the core microbiome of the mothers remained relatively stable during the study period. Breastfeeding and gender did not affect the microbial diversity in infants. Moreover, infants had a greater relative abundance of Firmicutes and a lower abundance of Actinobacteria, Bacteroidetes, Fusobacteria, and Proteobacteria than their mothers. The SparCC correlation analysis demonstrated constant changes in infants' oral microbial community network (p < 0.05). Conclusions: This study provides new evidence that the oral cavities of infants are colonized by a distinct group of bacterial species at birth. The acquisition and diversity of changes in oral microbial composition are dynamic during the first year of an infant's life. Before reaching the second birthday, the composition of the oral microbial community could be more similar to that of their biological mothers.

Photochemical separation of plutonium from uranium.

Plutonium-based technologies would benefit if chemical hazards for purifying plutonium were reduced. One critical processing step where improvements could be impactful is the adjustment of plutonium oxidation-states during separations. This transformation often requires addition of redox agents. Unfortunately, many of the redox agents used previously cannot be used today because their properties are deemed incompatible with modern day processing facilities and waste stream safety requirements. We demonstrated herein that photochemistry can be used as an alternative to those chemical agents. We observed that (1) Pu4+ → Pu3+ and UO22+ → U4+ photoreduction proceeded in HCl(aq) and HNO3(aq) and (2) photogenerated Pu3+(aq) and U4+(aq) could be separated using anion exchange chromatography (high yield, >90%; good separation factor, 322).

Structural guidelines for stabilization of α-helical coiled coils via PEG stapling.

Macrocyclization or stapling is one of the most well-known and generally applicable strategies for enhancing peptide/protein conformational stability and target binding affinity. However, there are limited structure- or sequence-based guidelines for the incorporation of optimal interhelical staples within coiled coils: the location and length of an interhelical staple is either arbitrarily chosen or requires significant optimization. Here we explore the impact of interhelical PEG stapling on the conformational stability and proteolytic resistance of a model disulfide-bound heterodimeric coiled coil. We demonstrate that (1) interhelical PEG staples are more stabilizing when placed farther from an existing disulfide crosslink; (2) e/g' staples are more stabilizing than f/b' or b/c' staples; (3) PEG staples between different positions have different optimal staple lengths; (4) PEG stapling tolerates variation in the structure of the PEG linker and in the mode of conjugation; and (5) the guidelines developed here enable the rational design of a stabilized PEG-stapled HER-2 affibody with enhanced conformational stability and proteolytic resistance.

Use of Magnetic Modulation of Nitrogen-Vacancy Center Fluorescence in Nanodiamonds for Quantitative Analysis of Nanoparticles in Organisms.

The fluorescence intensity emitted by nitrogen-vacancy (NV) centers in diamond nanoparticles can be readily modulated by the application of a magnetic field using a small electromagnet. By acquiring interleaved images acquired in the presence and absence of the magnetic field and performing digital subtraction, the fluorescence intensity of the NV nanodiamond can be isolated from scattering and autofluorescence even when these backgrounds are changing monotonically during the experiments. This approach has the potential to enable the robust identification of nanodiamonds in organisms and other complex environments. Yet, the practical application of magnetic modulation imaging to realistic systems requires the use of quantitative analysis methods based on signal-to-noise considerations. Here, we describe the use of magnetic modulation to analyze the uptake of diamond nanoparticles from an aqueous environment into Caenorhabditis elegans, used here as a model system for identification and quantification of nanodiamonds in complex matrices. Based on the observed signal-to-noise ratio of sets of digitally subtracted images, we show that nanodiamonds can be identified on an individual pixel basis with a >99.95% confidence. To determine whether surface functionalization of the nanodiamond significantly impacted uptake, we used this approach to analyze the presence of nanodiamonds in C. elegans that had been exposed to these functionalized nanodiamonds in the water column, with uptake likely occurring by ingestion. In each case, the images show a significant nanoparticle uptake. However, differences in uptake between the three ligands were not outside of the experimental error, indicating that additional factors beyond the surface charge are important factors controlling uptake. Analysis of the number of pixels above the threshold in individual C. elegans organisms revealed distributions that deviate significantly from a Poisson distribution, suggesting that uptake of nanoparticles may not be a statistically independent event. The results presented here demonstrate that magnetic modulation combined with quantitative analysis of the resulting images can be used to robustly characterize nanoparticle uptake into organisms.

Oxidizing Americium(III) with Sodium Bismuthate in Acidic Aqueous Solutions.

Historic perspectives describing f-elements as being redox "inactive" are fading. Researchers continue to discover new oxidation states that are not as inaccessible as once assumed for actinides and lanthanides. Inspired by those contributions, we studied americium(III) oxidation in aqueous media under air using NaBiO3(s). We identified selective oxidation of Am3+(aq) to AmO22+(aq) or AmO21+(aq) could be achieved by changing the aqueous matrix identity. AmO22+(aq) formed in H3PO4(aq) (1 M) and AmO21+(aq) formed in dilute HCl(aq) (0.1 M). These americyl products were stable for weeks in solution. Also included is a method to recover 243Am from the americium and bismuth mixtures generated during these studies.

Prerequisites for Stabilizing Long-Range Synergistic Interactions among b-, c-, and f-Residues in Coiled Coils.

Coiled coils are among the most abundant tertiary and quaternary structures found in proteins. A growing body of evidence suggests that long-range synergistic interactions among solvent-exposed residues can contribute substantially to coiled-coil conformational stability, but our understanding of the key sequence and structural prerequisites of this effect is still developing. Here, we show that the strength of synergistic interaction involving a b-position Glu (i), an f-position Tyr (i + 4), and a c-position Lys (i + 8) depends on the identity of the f-position residue, the length and stability of the coiled coil, and its oligomerization stoichiometry/surface accessibility. Combined with previous observations, these results map out predictable sequence- and structure-based criteria for enhancing coiled-coil stability by up to -0.58 kcal/mol per monomer (or -2.32 kcal/mol per coiled-coil tetramer). Our observations expand the available tools for enhancing coiled coil stability by sequence variation at solvent-exposed b-, c-, and f-positions and suggest the need to exercise care in the choice of substitutions at these positions for application-specific purposes.

Fusion Oncogenes Are Associated With Increased Metastatic Capacity and Persistent Disease in Pediatric Thyroid Cancers.

PURPOSE: In 2014, data from a comprehensive multiplatform analysis of 496 adult papillary thyroid cancer samples reported by The Cancer Genome Atlas project suggested that reclassification of thyroid cancer into molecular subtypes, RAS-like and BRAF-like, better reflects clinical behavior than sole reliance on pathologic classification. The aim of this study was to categorize the common oncogenic variants in pediatric differentiated thyroid cancer (DTC) and investigate whether mutation subtype classification correlated with the risk of metastasis and response to initial therapy in pediatric DTC. METHODS: Somatic cancer gene panel analysis was completed on DTC from 131 pediatric patients. DTC were categorized into RAS-mutant (H-K-NRAS), BRAF-mutant (BRAF p.V600E), and RET/NTRK fusion (RET, NTRK1, and NTRK3 fusions) to determine differences between subtype classification in regard to pathologic data (American Joint Committee on Cancer TNM) as well as response to therapy 1 year after initial treatment had been completed. RESULTS: Mutation-based subtype categories were significant in most variables, including age at diagnosis, metastatic behavior, and the likelihood of remission at 1 year. Patients with RET/NTRK fusions were significantly more likely to have advanced lymph node and distant metastasis and less likely to achieve remission at 1 year than patients within RAS- or BRAF-mut subgroups. CONCLUSION: Our data support that genetic subtyping of pediatric DTC more accurately reflects clinical behavior than sole reliance on pathologic classification with patients with RET/NTRK fusions having worse outcomes than those with BRAF-mutant disease. Future trials should consider inclusion of molecular subtype into risk stratification.

Ag-Diamond Core-Shell Nanostructures Incorporated with Silicon-Vacancy Centers.

Silicon-vacancy (SiV) centers in diamond have attracted attention as highly stable fluorophores for sensing and as possible candidates for quantum information science. While prior studies have shown that the formation of hybrid diamond-metal structures can increase the rates of optical absorption and emission, many practical applications require diamond plasmonic structures that are stable in harsh chemical and thermal environments. Here, we demonstrate that Ag nanospheres, produced both in quasi-random arrays by thermal dewetting and in ordered arrays using electron-beam lithography, can be completely encapsulated with a thin diamond coating containing SiV centers, leading to hybrid core-shell nanostructures exhibiting extraordinary chemical and thermal stability as well as enhanced optical properties. Diamond shells with a thickness on the order of 20-100 nm are sufficient to encapsulate and protect the Ag nanostructures with different sizes ranging from 20 nm to hundreds of nanometers, allowing them to withstand heating to temperatures of 1000 °C and immersion in harsh boiling acid for 24 h. Ultrafast photoluminescence lifetime and super-resolution optical imaging experiments were used to study the SiV properties on and off the core-shell structures, which show that the SiV on core-shell structures have higher brightness and faster decay rate. The stability and optical properties of the hybrid Ag-diamond core-shell structures make them attractive candidates for high-efficiency imaging and quantum-based sensing applications.

Isolation and characterization of a californium metallocene.

Californium (Cf) is currently the heaviest element accessible above microgram quantities. Cf isotopes impose severe experimental challenges due to their scarcity and radiological hazards. Consequently, chemical secrets ranging from the accessibility of 5f/6d valence orbitals to engage in bonding, the role of spin-orbit coupling in electronic structure, and reactivity patterns compared to other f elements, remain locked. Organometallic molecules were foundational in elucidating periodicity and bonding trends across the periodic table1-3, with a twenty-first-century renaissance of organometallic thorium (Th) through plutonium (Pu) chemistry4-12, and to a smaller extent americium (Am)13, transforming chemical understanding. Yet, analogous curium (Cm) to Cf chemistry has lain dormant since the 1970s. Here, we revive air-/moisture-sensitive Cf chemistry through the synthesis and characterization of [Cf(C5Me4H)2Cl2K(OEt2)]n from two milligrams of 249Cf. This bent metallocene motif, not previously structurally authenticated beyond uranium (U)14,15, contains the first crystallographically characterized Cf-C bond. Analysis suggests the Cf-C bond is largely ionic with a small covalent contribution. Lowered Cf 5f orbital energy versus dysprosium (Dy) 4f in the colourless, isoelectronic and isostructural [Dy(C5Me4H)2Cl2K(OEt2)]n results in an orange Cf compound, contrasting with the light-green colour typically associated with Cf compounds16-22.

Using molten salts to probe outer-coordination sphere effects on lanthanide(III)/(II) electron-transfer reactions.

Controlling structure and reactivity by manipulating the outer-coordination sphere around a given reagent represents a longstanding challenge in chemistry. Despite advances toward solving this problem, it remains difficult to experimentally interrogate and characterize outer-coordination sphere impact. This work describes an alternative approach that quantifies outer-coordination sphere effects. It shows how molten salt metal chlorides (MCln; M = K, Na, n = 1; M = Ca, n = 2) provided excellent platforms for experimentally characterizing the influence of the outer-coordination sphere cations (Mn+) on redox reactions accessible to lanthanide ions; Ln3+ + e1- → Ln2+ (Ln = Eu, Yb, Sm; e1- = electron). As a representative example, X-ray absorption spectroscopy and cyclic voltammetry results showed that Eu2+ instantaneously formed when Eu3+ dissolved in molten chloride salts that had strongly polarizing cations (like Ca2+ from CaCl2) via the Eu3+ + Cl1- → Eu2+ + ½Cl2 reaction. Conversely, molten salts with less polarizing outer-sphere M1+ cations (e.g., K1+ in KCl) stabilized Ln3+. For instance, the Eu3+/Eu2+ reduction potential was >0.5 V more positive in CaCl2 than in KCl. In accordance with first-principle molecular dynamics (FPMD) simulations, we postulated that hard Mn+ cations (high polarization power) inductively removed electron density from Lnn+ across Ln-Cl⋯Mn+ networks and stabilized electron-rich and low oxidation state Ln2+ ions. Conversely, less polarizing Mn+ cations (like K1+) left electron density on Lnn+ and stabilized electron-deficient and high-oxidation state Ln3+ ions.

High-Density Covalent Grafting of Spin-Active Molecular Moieties to Diamond Surfaces.

Functionalization of diamond surfaces with TEMPO and other surface paramagnetic species represents one approach to the implementation of novel chemical detection schemes that make use of shallow quantum color defects such as silicon-vacancy (SiV) and nitrogen-vacancy (NV) centers. Yet, prior approaches to quantum-based chemical sensing have been hampered by the absence of high-quality surface functionalization schemes for linking radicals to diamond surfaces. Here, we demonstrate a highly controlled approach to the functionalization of diamond surfaces with carboxylic acid groups via all-carbon tethers of different lengths, followed by covalent chemistry to yield high-quality, TEMPO-modified surfaces. Our studies yield estimated surface densities of 4-amino-TEMPO of approximately 1.4 molecules nm-2 on nanodiamond (varying with molecular linker length) and 3.3 molecules nm-2 on planar diamond. These values are higher than those reported previously using other functionalization methods. The ζ-potential of nanodiamonds was used to track reaction progress and elucidate the regioselectivity of the reaction between ethenyl and carboxylate groups and surface radicals.

Advancing understanding of actinide(iii) (Ac, Am, Cm) aqueous complexation chemistry.

The positive impact of having access to well-defined starting materials for applied actinide technologies - and for technologies based on other elements - cannot be overstated. Of numerous relevant 5f-element starting materials, those in complexing aqueous media find widespread use. Consider acetic acid/acetate buffered solutions as an example. These solutions provide entry into diverse technologies, from small-scale production of actinide metal to preparing radiolabeled chelates for medical applications. However, like so many aqueous solutions that contain actinides and complexing agents, 5f-element speciation in acetic acid/acetate cocktails is poorly defined. Herein, we address this problem and characterize Ac3+ and Cm3+ speciation as a function of increasing acetic acid/acetate concentrations (0.1 to 15 M, pH = 5.5). Results obtained via X-ray absorption and optical spectroscopy show the aquo ion dominated in dilute acetic acid/acetate solutions (0.1 M). Increasing acetic acid/acetate concentrations to 15 M increased complexation and revealed divergent reactivity between early and late actinides. A neutral Ac(H2O)6 (1)(O2CMe)3 (1) compound was the major species in solution for the large Ac3+. In contrast, smaller Cm3+ preferred forming an anion. There were approximately four bound O2CMe1- ligands and one to two inner sphere H2O ligands. The conclusion that increasing acetic acid/acetate concentrations increased acetate complexation was corroborated by characterizing (NH4)2M(O2CMe)5 (M = Eu3+, Am3+ and Cm3+) using single crystal X-ray diffraction and optical spectroscopy (absorption, emission, excitation, and excited state lifetime measurements).