Dominant Site Research Articles

Direct generation of high-valent iron-oxo species to eliminate oxytetracycline at circumneutral pH via paper mill sludge ash activating peroxymonosulfate

The excellent performance of high-valent iron-oxo species (FeIVO) in the degradation of pollutants by activating peroxymonosulfate (PMS) had attracted much attention. However, the generation and reaction mechanisms were still unclear. In this study, iron-rich paper mill sludge was used as a raw material for the first time to prepare iron-based catalysts with abundant octahedral FeIII sites (FeoctIII). The results showed that the highest content of FeoctIII was found in the paper mill sludge ash obtained by aerobic calcination at 800 °C (pmSA800), and the pmSA800 could exhibit excellent catalytic activity (0.4785 min−1) and stability during the oxytetracycline (OTC) degradation process. The characterization and density functional theory (DFT) calculations further indicated that the FeoctIII was the dominant active site for FeIVO production. PMS tended to be adsorbed on two adjacent FeoctIII sites to form a [FeoctIII-OSO2OO(H)-FeoctIII] complex with a two-site adsorption configuration. Subsequently, the OO and OH bonds in [FeoctIII-OSO2OO(H)-FeoctIII] broken by absorbing energy, generating FeIVO. It's worth noting that the Ca species of pmSA800 effectively stabilized the pH of the reaction solution, which ensured the stable and continuous production of FeIVO. This work provides a new idea and insight for preparing catalysts that could produce FeIVO active species.

Active Sites and Their Individual Turnover Frequencies for Ethylene Hydrogenation on Reduced Graphene Aerogel.

Graphene aerogel (GA) was reduced at various temperatures to prepare a series of reduced graphene aerogels (rGAs) with different surface characteristics. Detailed characterization demonstrated that an increase in the thermal reduction temperature leads to an increase in surface area accompanied by an increase in surface density of defect sites formed by the removal of the oxygen-containing functional groups. rGA samples were then tested for ethylene hydrogenation under identical conditions. A comparison of catalytic performances of each catalyst demonstrated that the rGA sample prepared by reduction in Ar at 900 °C (rGA-900) provides the highest performance compared with others prepared at lower temperatures. Next, we analyzed the per-gram activity of each catalyst as a sum of individual contributions from different defect sites quantified by Raman spectroscopy and CHNS-O analysis to determine the individual turnover frequencies (TOFs) of each active site. This analysis identified polyene-like structures and interstitial defects associated with amorphous sp2 bonded carbon atoms as the dominant active sites responsible for hydrogenation. A comparison of their TOFs further indicated that the polyene-like structures provide approximately ten times higher TOF compared to those associated with the amorphous carbon defects. These results, identifying the dominant active centers and quantifying their corresponding TOFs, provide opportunities toward the rational design of GA-based carbocatalysts.

Highly-dispersed Ni3Fe alloy nanoparticles anchored on MgAl-LDO for efficient catalytic amination of KA-oil to cyclohexylamine

The partial oxidation of cyclohexylamine to cyclohexanone oxime provides the new approach for preparation of caprolactam, which is vital important monomer of nylon-6 fibers and resins. In this work, a simple and efficient reductive amination of KA-oil to cyclohexylamine was developed over hydrotalcite-derived 9 %Ni-3 %Fe/MgAl-LDO catalyst. The results showed that the 9 %Ni-3 %Fe/MgAl-LDO catalyst exhibited the excellent catalytic performance, 97 % of cyclohexanol conversion and 99 % of cyclohexanone conversion were achieved with 98 % of selectivity to cyclohexylamine over 100 h at 170 °C. The highly-dispersed Ni3Fe alloy nanoparticles anchored on MgAl-LDO are responsible for the excellent catalytic performance and stability of catalyst. Moreover, the Ni sites of Ni3Fe alloy (111) facet as dominant catalytic active sites were identified by DFT calculation. The present work provides a new approach for green preparation of cyclohexylamine from reductive amination of KA-oil over hydrotalcite-derived 9 %Ni-3 %Fe/MgAl-LDO catalyst, and has important industrial application prospects.

Solvent-free synthesis of foam board-like CoSe2 alloy to selectively generate singlet oxygen via peroxymonosulfate activation for sulfadiazine degradation

Singlet oxygen (1O2) is a highly effective reactive species in selectively oxidizing organic pollutants. However, it is still challenging to rationally design robust catalysts for the selective generation of 1O2. Herein, the coordination and engineering architecture of the foam board-like CoSe2 alloy were facilely constructed through a green solvent-free method and displayed almost 100% 1O2 production selectivity. The CoSe2 alloy showed excellent catalytic ability for the efficient and fast removal of organic pollutants via peroxymonosulfate (PMS) activation compared with previously reported cobalt-based catalysts. The CoSe2/PMS system exhibited strong resistance for a broad pH range (3.0–11.0) and various coexisting inorganic ions owing to the advantage of the strong bonding of Co-Se in CoSe2 alloy. Mechanism studies revealed that 1O2 was the only reactive oxygen species in the CoSe2/PMS system. Theoretical calculations demonstrated that Co was the dominant adsorption site for PMS in CoSe2, and the production pathway of 1O2 was PMS* → *OH → *O → 1O2. In addition, it was proved that *OH and *O served as the rate-determining steps for the formation of 1O2 by PMS activation on CoSe2 alloy. These findings provide a rational strategy for preparing a series of low-cost transition metal-based alloy catalysts for PMS activation to achieve high-efficiency 1O2 production in the elimination of organic pollutants.

Cytidine Acetylation Across the Tree of Life.

Acetylation plays a critical role in regulating eukaryotic transcription via the modification of histones. Beyond this well-documented function, a less explored biological frontier is the potential for acetylation to modify and regulate the function of RNA molecules themselves. N4-Acetylcytdine (ac4C) is a minor RNA nucleobase conserved across all three domains of life (archaea, bacteria, and eukarya), a conservation that suggests a fundamental role in biological processes. Unlike many RNA modifications that are controlled by large enzyme families, almost all organisms catalyze ac4C using a homologue of human Nat10, an essential disease-associated acetyltransferase enzyme.A critical step in defining the fundamental functions of RNA modifications has been the development of methods for their sensitive and specific detection. This Account describes recent progress enabling the use of chemical sequencing reactions to map and quantify ac4C with single-nucleotide resolution in RNA. To orient readers, we first provide historical background of the discovery of ac4C and the enzymes that catalyze its formation. Next, we describe mechanistic experiments that led to the development of first- and second-generation sequencing reactions able to determine ac4C's position in a polynucleotide by exploiting the nucleobase's selective susceptibility to reduction by hydride donors. A notable feature of this chemistry, which may serve as a prototype for nucleotide resolution RNA modification sequencing reactions more broadly, is its ability to drive a penetrant and detectable gain of signal specifically at ac4C sites. Emphasizing practical applications, we present how this optimized chemistry can be integrated into experimental workflows capable of sensitive, transcriptome-wide analysis. Such readouts can be applied to quantitatively define the ac4C landscape across the tree of life. For example, in human cell lines and yeast, this method has uncovered that ac4C is highly selective, predominantly occupying dominant sites within rRNA (rRNA) and tRNA (tRNA). By contrast, when we extend these analyses to thermophilic archaea they identify the potential for much more prevalent patterns of cytidine acetylation, leading to the discovery of a role for this modification in adaptation to environmental stress. Nucleotide resolution analyses of ac4C have also allowed for the determination of structure-activity relationships required for short nucleolar RNA (snoRNA)-catalyzed ac4C deposition and the discovery of organisms with unexpectedly divergent tRNA and rRNA acetylation signatures. Finally, we share how these studies have shaped our approach to evaluating novel ac4C sites reported in the literature and highlight unanswered questions and new directions that set the stage for future research in the field.

Dehydrative decarbonylation of fatty acids into long-chain olefins over CoNx/NC catalysts

The development of highly efficient, low-cost supported catalysts is crucial for directly deoxygenating biomass fatty acids to long-chain olefins. However, additive-free olefin production, by dehydrative decarbonylation from fatty acids, is scarcely conducted owing to competing decarboxylation reactions. Herein, a green and cost-effective strategy is presented to improve the Co-catalyzed dehydrative decarbonylation of stearic acid, which produces a mixture of heptadecenes with yields of up to 41.3 % and a paraffin yield of 14.7 %. Experimental data, along with a detailed catalyst characterization, revealed that the surface CoNx species acted as the dominant active sites. Furthermore, the specific catalytic performance can be attributed to the dense defect sites, abundant vacancies, and mesoporous structures of the N-doped Carbon (NC) support. The as-prepared CoNx/NC catalysts were recovered and reused up to three times without significant deactivation. Additionally, we propose a possible reaction mechanism for fatty acid deoxygenation. This research makes a significant contribution toward advancing the performance of noble-metal-free deoxygenation catalysts for the production of unsaturated compounds in biomass conversions.

Examining factors influencing the user’s loyalty on algorithmic news recommendation service

Based on user-related data, an algorithmic news recommendation service (ANRS) predicts users’ reading preferences and selectively recommends news. Given the double-edged opinions on ANRS, identifying and managing crucial factors influencing users’ satisfaction and trust in this service will be essential for service providers and developers. However, few studies have tried to find these factors or develop a more precise understanding of users’ perceptions of this service. Therefore, this study aims to examine factors affecting users’ loyalty to ANRS with partial least squares structural equation modelling (PLS-SEM). This study conducted an online survey for users of “My News”, the free mobile ANRS of NAVER, Korea’s dominant online portal site, and analyzed the data from 483 responses. This analysis verified that both satisfaction and trust positively affect loyalty to ANRS, and trust positively affects satisfaction. Moreover, it was found that perceived accuracy positively affects satisfaction. The result also showed that perceived news value and perceived transparency positively affect trust, and privacy concerns negatively affect it. Lastly, it was found that perceived usability and pre-existing attitude toward the service provider positively affect satisfaction and trust. The results and discussions will be helpful for service providers and developers to manage ANRS effectively based on users’ responses and perceptions of this service.

Zinc and sulfur functionalized biochar as a peroxydisulfate activator via deferred ultraviolet irradiation for tetracycline removal.

To enhance the degradation of tetracycline class (TC) residuals of high-concentration from pharmaceutical wastewater, a novel zinc (Zn) and sulfur (S) functionalized biochar (SC-Zn), as a peroxydisulfate (PDS) activator, was prepared by two-step pyrolysis using ZnSO4 accumulated water-hyacinth. Results showed that the removal rate of 50, 150, and 250 mg per L TC reached 100%, 99.22% and 94.83% respectively, by the SC-Zn/PDS system at a dosage of 0.3 g per L SC-Zn and 1.2 mM PDS, via the deferred ultraviolet (UV) irradiation design. Such excellent performance for TC removal was due to the synergetic activation of PDS by the biochar activator and UV-irradiation with biochar as a responsive photocatalyst. The functionalization of the co-doped Zn and S endowed the biochar SC-Zn with a significantly enhanced catalytic performance, since Zn was inferred to be the dominant catalytic site for SO4˙- generation, while S played a key role in the synergism with Zn by acting as the primary adsorption site for the reaction substrates. The employed SC-Zn/PDS/UV system had excellent anti-interference under different environmental backgrounds, and compared with the removal rate of TC by adsorption of SC-Zn, the increasing rate in the SC-Zn/PDS/UV system (18.75%) was higher than the sum of the increases in the SC-Zn/PDS (9.87%) and SC-Zn/UV systems (3.34%), furtherly verifying the systematic superiority of this synergy effect. This study aimed to prepare a high-performance functionalized biochar activator and elucidate the rational design of deferred UV-irradiation of PDS activation to efficiently remove high-concentration antibiotic pollutants.

Identification and characterization of linear epitopes of monoclonal antibodies against the capsid proteins of small ruminant lentiviruses.

Maedi-visna virus (MVV) and caprine arthritis encephalitis virus (CAEV) are members of a group of genetically highly homologous lentiviruses collectively referred to as small ruminant lentiviruses (SRLVs). SRLVs can infect sheep, goats and other small ruminants, causing multisystemic disease with progressive and persistent inflammatory changes, severely reducing animal productivity and impeding animal trade. The capsid protein of SRLVs, p28, is highly conserved among strains and is a commonly used marker for the detection of SRLVs. In this study, two monoclonal antibodies (mAbs), designated G8F7 and A10C12, against p28 were generated using a recombinant p28 protein expressed in Escherichia coli as an immunogen. Functional analysis showed that these two monoclonal antibodies could be used in iELISA, immunofluorescence assays (IFA) and western blot assays to detect p28 or Gag precursor proteins of SRLVs. Two linear epitopes, 61GNRAQKELIQGKLNEEA77 (E61-77) and 187CQKQMDRVLGTRVQQATVEEKMQACR212 (E187-212), which are recognized by G8F7 and A10C12, respectively, were identified through truncation of the GST-fused p28. Amino acid sequence alignment showed that the epitope E61-77 is conserved among SRLVs, with a dominant mutation site (K72R) that does not disrupt recognition by G8F7. E187-212 was found to exhibit variability among SRLVs, but the majority of mutant epitopes are recognized by A10C12, with the exception of a mutant epitope from an isolate with undefined subtypes from Ovis aries, which was not recognized. These findings may facilitate future study of SRLVs and promote the development of methods for the detection of these viruses.

Kinetic insights into structure sensitivity of Ru catalyzed l-alanine hydrogenation to alaninol

Ru(101) sites are identified as the dominant active sites for the hydrogenation of l-alanine to alaninol.

Culture(s) on the Margins: An Introduction

Sociologists and those working in related disciplines have often found more of interest on the margins than in the centre. It is where innovation takes place, where the new replaces the outmoded, where ‘outsider’ or heterodox voices challenge the orthodoxy, and where culture creators are most able to follow the laws inherent to their specific region of the cultural field. The margins are where you will find ‘underground’ or ‘cutting edge’ scenes. Moreover, ethnographic traditions in sociological research have produced fine-grained accounts of cultures of subaltern, subcultural, diasporic groups, and the ways in which these groups and individuals engage in counter-hegemonic practices. At the same time, sociologists have also drawn attention to how those occupying the margins of societal fields are characterised in terms of lack: dominated individuals and groups lack the requisite cultural capital or social connections to get on in life. This special issue, which derives from discussions held at the Culture(s) on the Margins mid-term Sociology of Culture Research Network (European Sociological Association) conference at University of Portsmouth in the summer of 2022, contributes to debates on the relatively underexplored topic of culture(s) on the margins through several conceptual and empirical interventions. In doing so, it focuses on three interrelated aspects of marginality: first, marginality as a site of domination; second, marginality as opening up spaces of resistance; and third, marginality as enabling different ways of seeing and thinking.

The impact of water on gas storage in organic-rich rocks

To achieve CO2 storage in organic-rich rocks such as coal and shale, the influence of H2O generated by organic matter and co-occurring CH4 and N2 cannot be neglected. Based on the molecular model of coal and kerogen established using Materials Studio, and verification of CH4 isothermal adsorption from 20 to 100 oC, the competitive adsorption between CH4、CO2、N2 and H2O is discussed. Both the coal and shale kerogen molecular models show similar relative adsorption capacities, namely H2O > CO2 > CH4 > N2. Competitive adsorption is more obvious in small pores with a greater apparent inhibiting effect of H2O on the gases. The adsorption of CO2, CH4 and N2 decreases to zero at 75 ℃ in the kerogen model. A positive correlation is shown between the charge transfer and the adsorption capacity, and the adsorption onto carboxyl group occurs indicate that H2O has the highest adsorption preference. The oxygen-containing functional group is the dominant adsorption site for H2O, with the carboxyl group being the best adsorption site. The hydroxyl group is the optimal site for all gases, while all lower than H2O. The adsorption heat released are of H2O>CO2 >CH4 >N2 sequences, which is consistent with the change in the amount adsorbed.

Dual-Atom Catalyst with N-Colligated Zn1Co1 Species as Dominant Active Sites for Propane Dehydrogenation.

Dual-atom catalysts (DACs) with paired active sites can provide unique intrinsic properties for heterogeneous catalysis, but the synergy of the active centers remains to be elucidated. Here, we develop a high-performance DAC with Zn1Co1 species anchored on nitrogen-doped carbon (Zn1Co1/NC) as the dominant active site for the propane dehydrogenation (PDH) reaction. It exhibits several times higher turnover frequency (TOF) of C3H8 conversion and enhanced C3H6 selectivity compared to Zn1/NC or Co1/NC with only a single-atom site. Various experimental and theoretical studies suggest that the enhanced PDH performance stems from the promoted activation of the C-H bond of C3H8 triggered by the electronic interaction between Zn1 and Co1 colligated by N species. Moreover, the dynamic sinking of the Zn1 site and rising of the Co1 site, together with the steric effect of the dissociated H species at the bridged N during the PDH reaction, provides a feasible channel for C3H6 desorption through the more exposed Co1 site, thereby boosting the selectivity. This work provides a promising strategy for designing robust hetero DACs to simultaneously increase activity and selectivity in the PDH reaction.

Atomic-level characterization of η-twins with non-homogeneous nucleation on the E(Al18Mg3Cr2) phase in 7075 alloy: TEM observations and DFT calculations

In this work, an uncommon type of η-twin with non-homogeneous nucleation on the surface of the E-phase is characterized, and two defects and growth processes of the twin are analyzed. According to the transmission electron microscopy image analysis, heterogeneous nucleation of the η phase at the dominant site of the E phase can lead to the formation of such η-twin only when a rather strict site-direction relationship is satisfied as well as when it is at the interface adjacent to the E phase. The formation of twin defects is related to the E phase but ultimately determined by the nature of the η phase, and the crystallographic relationship between the defect structure and the E phase is self-consistent. Combined with the analytical results from STEM, first-principles calculations show that the solute segregation at the defects reduces the total energy of the system, which favors the transition of the η phase of the heterogeneous nucleation and the formation of twins, and that solute Al is more favorable than Mg. In addition, the elemental distribution and effects in the precipitation-free zone were analyzed by EDS mapping.

Climate change altered the dynamics of stand dominant height in forests during the past century – Analysis of 20 European tree species

Analyzing how climate change has affected forest growth is crucial for predicting future dynamics and adapting forest management to future climate change. In this paper, we investigate how climate change has modified stand dominant height dynamics and site index of 20 European tree species. We used an innovative method based on an annual height increment equation to model stand dominant height as a function of climate back to 1872 and of other stand environmental conditions. We used these models to simulate stand dominant height dynamics and site index under two different climates (prior to climate change and actual recent climate) to analyze the impact of climate change over the past century. To build our models, we combined the recently published FYRE long-term climate database, which provides daily data since 1871, with data from more than 17,000 forest stands of the French National Forest Inventory network. Higher temperature, precipitation and climatic water balance generally favor stand dominant height dynamics when the variables are considered separately. However, the positive effects often saturate at the higher end of the variable distribution. Over the past century, the effect of climate change on the site index has varied widely among species, ranging from a decrease of less than 3% to an increase of more than 5%. The effect of climate change has also varied within species, with more positive effects on initially temperature-limited stands for some species. For the species and environmental conditions considered, our results highlight a positive response of site index to past climate change for most species, albeit with between- and within-species differences. Our results also suggest that this positive response could become negative under continued climate change. These conclusions, as well as the quantitative relationships we provide between climate and stand dominant height dynamics or site index, will help design management strategies to adapt forests to climate change.

Starch of oat derived nanostructured Fe/Mn bimetallic carbon materials for sulfamethoxazole degradation via peroxymonosulfate activation

Fe/Mn bimetallic carbon materials were synthesized by combining oat and urea, followed by and carbonization processes, the activity and mechanism of the obtained materials in activating peroxymonosulfate (PMS) for sulfamethoxazole (SMX) degradation were determined. Data suggested that the obtained material (CN@FeMn-10-800) showed the optimal performance for SMX degradation under the1:8:0.05:0.05 mass ratios of oat/urea/Fe/Mn. Around 91.2 % SMX (10 mg L−1) was removed under the conditions of 0.15 g L−1 CN@FeMn-10-800 and 0.20 g L−1 PMS. The CN@FeMn-10-800 showed great adaptability under different conditions, satisfactory activation repeatability and versatility. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that core-shell structure with rich porous of CN@FeMn-10-800 was achieved. Quenching test and electron paramagnetic resonance (EPR) indicated that surface bound oxygen and singlet oxygen (1O2) were the dominate reactive groups in this system. X-ray photoelectron spectroscopy (XPS) suggested that graphite N, Fe0, Fe3C and Mn(II) were the dominant active sites. Through the work, a simple strategy could be found to make high-value use of biomass and use it to effectively purified wastewater.

The activation mechanism of peroxymonosulfate and peroxydisulfate by modified hydrochar: Based on the multiple active sites formed by N and Fe

Modified hydrochar (NHC@Fe), with multiple functional groups and transition metal oxide-containing surface, was successfully synthesized by one-step hydrothermal method. The differences in its catalytic activity for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation were studied in detail. Experimental and DFT studies showed that abundant active sites, namely, transition metals and functional groups on NHC@Fe provided multiple effective pathways for the activation of persulfate (PS). The NHC@Fe/PMS and NHC@Fe/PDS systems could degrade about 80% of tetracycline hydrochloride (TC) in 120 min and were found to be better than those modified by iron or nitrogen alone. This emphasized the advantage of N–Fe co-modification in persulfate activation. Although the Fe2+/Fe3+ cycle accelerated the activation, the activation of PMS mainly relied on Fe3+, whereas that of PDS mainly relied on Fe2+. Moreover, Fe–N, pyrrolic N, pyridine N, C–O, and O–CO groups also played a key role in the activation process, but the dominant action sites were not the same. Multiple free radicals, such as SO4•—, •OH, O2•—, and 1O2 were generated in PMS and PDS activation systems. 1O2 induced non-free radical pathway was mainly involved in the degradation of TC in both activation systems, but the generation pathway of 1O2 was more direct and rapid in the PDS system. This study provides detailed DFT models of the active sites activated by PMS and PDS and discusses the activation pathways of PMS and PDS along with the similarities and differences in ROS reaction mechanisms.

Structure and Electron Engineering for Nitrate Electrocatalysis to Ammonia: Identification and Modification of Active Sites in Spinel Oxides.

Cobalt spinel oxides, which consist of tetrahedral site (AO4) and octahedral site (BO6), are a potential group of transition metal oxides (TMO) for electrocatalytic nitrate reduction reactions to ammonia (NRA). Identifying the true active site in spinel oxides is crucial to designing advanced catalysts. This work reveals that the CoO6 site is the dominant site for NRA through the site substitution strategy. The suitable electronic configuration of Co at the octahedral site leads to a stronger interaction between the Co d-orbital and the O p-orbital in O-containing intermediates, resulting in a high-efficiency nitrate-to-ammonia reduction. Furthermore, the substitution of metallic elements at the AO4 site can affect the charge density at the BO6 site via the structure of A-O-B. Thereafter, Ni and Cu are introduced to replace the tetrahedral site in spinel oxides and optimize the electronic structure of CoO6. As a result, NiCo2O4 exhibits the best activity for NRA with an outstanding yield of NH3 (15.49mgcm-2h-1) and FE (99.89%). This study introduces a novel paradigm for identifying the active site and proposes an approach for constructing high-efficiency electrocatalysts for NRA.

Breeding habitat selection of three sympatric species of Mediterranean warblers in eastern Spain

Understanding habitat selection patterns in congeneric species has raised special interest due to its importance when designing conservation strategies for the species. We analysed reproductive habitat selection of three coexisting warbler species in the eastern Iberian Peninsula. We detected the individuals by their vocalizations at 40 listening points in two study areas (Carcaixent and Alcoy). We used satellite images to identify different vegetation types and their availability. Reproductive habitat selection was analysed by the Ivlev selectivity index and a compositional analysis. In addition, we determined the effect of different habitat variables (dominant vegetation, vegetation height, cover and site) on the presence of the species fitting a binomial GLM with logistic linking function. We found that the Sardinian Warbler ( Curruca Melanocephala) selected scrub-dominated areas; while the Dartford Warbler ( C. undata) preferred areas with low (<50%) vegetation cover; and the Subalpine Warbler ( C. cantillans) was present in areas with scrubs and low (<50%) vegetation cover, avoiding crops. The compositional analysis showed that the species used different vegetation types, in relation to their availability and that the selection differed between species. The Sardinian Warbler was the only species which showed spatial variation in reproductive habitat selection. Our results evidence that the studied warbler species select and avoid different types of vegetation in relation to their specific requirements and the present habitat structure. This represents valuable information to understand the composition of local communities and the reproductive habitat selection of the studied species.

Uranium(VI) interactions with Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I

Pseudomonas sp. are indigenous inhabitants of ombrotrophic bogs which can survive in acidic, nutrient-poor environments with wide temperature fluctuations. Their interactions with contaminant radionuclides can influence radionuclide biogeochemistry in boreal environment. Here, uranium (U(VI)) bioassociation by Pseudomonas sp. PS-0-L, V4-5-SB and T5-6-I isolated from a boreal bog was studied by a combination of batch contact experiments, spectroscopy and microscopy. All strains removed U from the solution and the U bioassociation efficiency was affected by the nutrient source, incubation temperature, time and pH. Highest U bioassociation occurred in the strains PS-0-L (0.199 mg U/gBDW) and V4-5-SB (0.223 mg U/gBDW). Based on in-situ attenuated total reflection Fourier transformation infrared spectroscopy (ATR FT-IR) analyses, the most likely functional groups responsible for U binding were the cell surface carboxyl groups. In addition, transmission electron microscopy with energy dispersive X-ray spectroscopy (TEM/EDX) showed dense intra-cellular round- and needle-like U accumulations in the cytoplasm and near to the inner cell membrane. The presence of U with phosphorus was indicated in elemental mapping. Modelled data showed ≡ SOOHx−1 and ≡ SOCO2Hx−1 as the dominant surface sites, contributing to the negative cell surface charge. The U removal efficiency depended on the U(VI) speciation under different pH conditions. At pH 5, the main species reacting with bacterial cell surfaces was UO22+, while at pH 9 UO2(OH)2 and UO2(OH)3- dominated the reactions. Further, U bioassociation increased with increasing aqueous U(VI) concentrations. Our data suggests U bioassociation on 1) outer cell membrane/cell wall associated carboxyl groups (e.g., proteins), and 2) intracellular phosphate groups (e.g., phospholipids).