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Microparticles of iron oxide (MPIOs) are increasingly used for contrast generation in magnetic resonance imaging (MRI). In particular, Dynabeads® MyOne™ Tosylactivated MPIOs have enabled sensitive and targeted molecular imaging, e.g., to detect vascular inflammation. For the first time we measured the relaxivities as well as the molar susceptibility χ

The photocatalytic performance of the semiconductor CdS can be improved with carbon materials capable of limiting photocorrosion and the fast recombination of photogenerated charges. For this purpose, carbon derived from biomass exhibit several advantages including low cost, high abundance, and renewability. Here, photocatalytic CdS nanorods modified with carbon derived from the leaves of Japanese raisin trees were synthesized via a single hydrothermal step. Composite CdS nanorods with 5% biomass-derived carbon photocatalyzed H2 evolution 1.8 times faster than unmodified CdS at a rate of 5.71 mmol g−1 h−1. The apparent quantum efficiency of 5%C/CdS nanorods was 14.96%. Furthermore, the addition of biomass-derived carbon to CdS nanorods augmented the stability of the semiconductor under visible light. The characterization of the composite PC indicated that a larger specific surface area, as well as upgraded charge separation caused by biomass-derived carbon, were involved in the acceleration of photocatalytic hydrogen production.

Low-cost photocatalysts are being developed for the conversion of visible light into H2 and to drive CO2 reduction. Hybrid photosynthesis is a promising approach to convert CO2 and visible light into multicarbon compounds where a photocatalyst energizes the metabolism of an autotrophic microbe. Here, a heterostructure ZnSe/ZnS photocatalyst was synthesized by a simple one-pot method and evaluated for photocatalytic H2 evolution (PHE) as well as for hybrid photosynthesis with the bioplastic-producing bacterium Ralstonia eutropha. ZnSe/ZnS nanoparticles exhibited a PHE 5.5 times higher than pure ZnSe. Photoluminescence and photoelectrochemical characterization of ZnSe/ZnS demonstrated more efficient charge separation probably caused by ZnS defects. Furthermore, ZnSe/ZnS improved 1.3 times bioplastic production from CO2 by R. eutropha, which was not the case for pure ZnSe. These results show ZnSe/ZnS potential for both PHE as well as hybrid photosynthesis and provide insights on the photocatalytic reaction mechanisms involved when the two Zn-based materials are combined.

The photocatalytic production of H2 by low-cost semiconductors is a promising approach to store solar energy. Photocatalysts with heterojunctions convert visible light into H2 faster because of more efficient charge separation. The morphology, the structure, and the crystallinity are additional factors to consider when developing a photocatalyst. Here, highly-crystalline CdS nanorod (NR) were synthesized by a facile one-pot process. Under visible light, pure CdS NR produced H2 2.1 times faster than conventional CdS nanoparticles (NP). CdS NR were then combined with the semiconductor red phosphorus (RPh). A CdS NR-based heterojunction photocatalyst with RPh5% had an excellent photocatalytic H2 evolution rate of 11.72 mmol g−1 h−1, which was 3.6 times higher than pure CdS NR. The apparent quantum efficiency of RPh5%/CdS NR was 19.57%. Furthermore, RPh5%/CdS NR exhibited a superior photogenerated charge separation efficiency and was stable with little photocorrosion compared to CdS NP showing the high potential of this heterojunction photocatalyst.

Crystal plane regulation, defect engineering, and element doping can effectively solve the problems of large band gaps, poor light absorption, and fast recombination of BiOCl. In this work, iodine-doped BiOCl (I/BiOCl) nanowafers with abundant (110) crystal planes and oxygen vacancies (OV) were prepared by a simple hydrothermal method and assessed for pollutant photodegradation. I/BiOCl with a molar ratio of I to Cl of 0.6 (I

New technologies have expanded the available methods to help individuals learn or re-learn motor skills. Despite equivocal evidence for the impact of robotic guidance for motor skill acquisition (Marchal-Crespo, McHughen, Cramer, & Reinkensmeyer, 2010), we have recently shown that robotic guidance mixed with unassisted practice can significantly improve the learning of a golf putting task (Bested & Tremblay, 2018). To understand the mechanisms associated with this new mixed approach (i.e., unassisted and robot-guided practice) for the learning of a golf putting task, the current study aimed to determine if such mixed practice extends to one's ability to detect errors. Participants completed a pre-test, an acquisition phase, as well as immediate, delayed (24-h), and transfer post-tests. During the pre-test, kinematic data from the putter was converted into highly accurate, consistent, and smooth trajectories delivered by a robot arm. During acquisition, 2 groups performed putts towards 3 different targets with robotic guidance on either 0% or 50% of acquisition trials. Only the 50% guidance group significantly reduced ball endpoint distance and variability, as well as ball endpoint error estimations, between the pre-test and the post-tests (i.e., immediate retention, 24-h retention, and 24-h transfer). The current study showed that allowing one to experience both robotic guidance and unassisted (i.e., errorful) performances enhances one's ability to detect errors, which can explain the beneficial motor learning effects of a mixed practice schedule.

A limb’s initial position is often biased to the right of the midline during activities of daily living. Given this specific initial limb position, visual cues of the limb become first available to the ipsilateral eye relative to the contralateral eye. The current study investigated online control of the dominant limb as a function of having visual cues available to the ipsilateral or contralateral eye, in relation to the initial start position of the limb. Participants began each trial with their right limb on a home position to the left or right of the midline. After movement onset, a brief visual sample was provided to the ipsilateral or contralateral eye. On one third of the trials, an imperceptible 3 cm target jump was introduced. If visual information from the eye ipsilateral to the limb is preferentially used to control ongoing movements of the dominant limb, corrections for the target jump should be observed when movements began from the right of the body’s midline and vision was available to the ipsilateral eye. As expected, limb trajectory corrections for the target jump were only observed when participants started from the right home position and visual information was provided to the ipsilateral eye. We purport that such visuomotor asymmetry specialization emerges via neurophysiological developments, which may arise from naturalistic and probabilistic limb trajectory asymmetries.

Manual handling training may be improved if it relied on the provision of individualized, augmented feedback about key movement features. The purpose of this study was to compare the reduction in sagittal spine motion during manual lifting tasks following two training approaches: didactic (DID) and augmented feedback (AUG). Untrained participants (n = 26) completed lifting tests (box, medication bag, and paramedic backboard) and a randomly-assigned intervention involving 50 practice box lifts. Lifting tests were performed immediately before and after training, and one-week after interventions. Both groups exhibited reductions in spine motions immediately and one-week after the interventions. However, the AUG intervention group elicited significantly greater reductions in 5 of 12 between-group comparisons (3 tasks × 4 spine motion variables). The results of the current study support the use of augmented feedback-based approaches to manual handling training over education-based approaches.

The purpose of the present study was to assess the degree to which children and adolescents represent and match the observed body parts of others onto the internal representation of their own body parts. Male and female participants of different age groups (7–9, 10–12, and 13–16 years old) completed a body-part compatibility task in which they responded to coloured targets (relevant feature) presented over the hand or foot (irrelevant feature) of pictures of male models of different ages (7, 11, and 15 years old). Body-part compatibility effects emerged for the males in the 10–12 and 13–16-year-old age groups, which only occurred when viewing models of their own age-group peers (i.e., 11 and 15 year old models, respectively). In contrast, no body-part compatibility effects were found for males in the 7–9-year-old group nor in any of the three groups of females. Based on these data, it is suggested that children and adolescent males seem to develop the ability to match the bodies of other males to their own after 9 years of age and this matching process seems strongest for their age-matched peers.

When moving our upper-limb towards a single target, movement times are typically shorter than when movement to a second target is required. This is known as the one-target advantage. Most studies that have demonstrated the one-target advantage have employed separate trial blocks for the one- and two-segment movements. To test if the presence of the one-target advantage depends on advance knowledge of the number of segments, the present study investigated whether the one-target advantage would emerge under different trial orders/sequences. One- and two-segment responses were organized in blocked (i.e., 1-1-1, 2-2-2), alternating (i.e., 1-2-1-2-1-2), and random (i.e., 1-1-2-1-2-2) trial sequences. Similar to previous studies, where only blocked schedules have typically been utilized, the one-target advantage emerged during the blocked and alternate conditions, but not in the random condition. This finding indicates that the one-target advantage is contingent on participants knowing the number of movement segments prior to stimulus onset.

Movement times are significantly shorter when moving from a start position to a single target, compared to when one has to continue onto a second target (i.e., the one-target advantage [OTA]). To explain this movement time difference, both the movement integration and the movement constraint hypotheses have been proposed. Although both hypotheses have been found to have explanatory power as to why the OTA exists, the support for each has been somewhat equivocal. The current review evaluated the relative support in the literature for these two hypotheses. Ultimately, preferential support for each theoretical explanation was found to be related to the higher indices of difficulty (IDs: Fitts, 1954) employed. That is, studies that included higher IDs (i.e., 6-8 bits) were more likely to provide more support for the movement constraint hypothesis, whereas studies employing lower IDs (i.e., 1-4 bits) were more likely to provide more support for the movement integration hypothesis. When the IDs employed were relatively intermediate (i.e., 5 bits), both hypotheses were mostly supported. Thus, task difficulty is crucial when determining which hypothesis better explains the planning and control of sequential goal-directed movements. Critically, the OTA most likely always involves integration but may also involve constraining if the accuracy demands are sufficiently high.

Objective To investigate the potential benefits of 3 therapeutic instrumental music performance (TIMP)-based interventions in rehabilitation of the affected upper-extremity (UE) for adults with chronic poststroke hemiparesis. Design Randomized-controlled pilot study. Setting University research facility. Participants Community-dwelling volunteers (N=30; 16 men, 14 women; age range, 33-76 years; mean age, 55.9 years) began and completed the protocol. All participants had sustained a unilateral stroke more than 6 months before enrollment (mean time poststroke, 66.9 months). Intervention Two baseline assessments, a minimum of 1 week apart; 9 intervention sessions (3 times/week for 3 weeks), in which rhythmically cued, functional arm movements were mapped onto musical instruments; and 1 post-test following the final intervention. Participants were block-randomized to 1 of 3 conditions: group 1 (45 minutes TIMP), group 2 (30 minutes TIMP, 15 minutes metronome-cued motor imagery [TIMP+cMI]), and group 3 (30 minutes TIMP, 15 minutes motor imagery without cues [TIMP+MI]). Assessors and investigators were blinded to group assignment. Main Outcome Measures Fugl-Meyer Upper-Extremity (FM-UE) and Wolf Motor Function Test- Functional Ability Scale (WMFT-FAS). Secondary measures were motor activity log (MAL)–amount of use scale and trunk impairment scale. Results All groups made statistically significant gains on the FM-UE (TIMP, P=.005, r=.63; TIMP+cMI, P=.007, r=.63; TIMP+MI, P=.007, r=.61) and the WMFT-FAS (TIMP, P=.024, r=.53; TIMP+cMI, P=.008, r=.60; TIMP+MI, P=.008, r=.63). Comparing between-group percent change differences, on the FM-UE, TIMP scored significantly higher than TIMP+cMI (P=.032, r=.57), but not TIMP+MI. There were no differences in improvement on WMFT-FAS across conditions. On the MAL, gains were significant for TIMP (P=.030, r=.54) and TIMP+MI (P=.007, r=.63). Conclusion TIMP-based techniques, with and without MI, led to significant improvements in paretic arm control on primary outcomes. Replacing a physical training segment with imagery-based training resulted in similar improvements; however, synchronizing internal and external cues during auditory-cMI may pose additional sensorimotor integration challenges.

Research Objectives To use a novel limb acceleration measure to reveal mechanisms of improved paretic limb control following music-based rehabilitation. Design A consecutive sample. Setting A music and health research facility in Toronto, CA. Participants 30 community dwellers aged 30-79 years in the chronic stroke phase with minimal volitional control of the affected limb. Interventions Nine training sessions thirty-minutes in length were administered three times per week by a Neurologic Music Therapist. The music-based training incorporated mapping rhythmically cued functional arm movements onto digital sonification touch tablets. The paretic limb's acceleration profile was recorded at 1000 Hz from a wrist-worn accelerometer. Main Outcome Measures Estimates of power-spectral-density were obtained with an approximately 1-s sliding window and a 50% window overlap across the entire training session. The power-spectral-density was computed as the median of all the windows within each trace. The dominant peak in the function was then identified and quantified as the height of the peak (i.e., peak-power). Peak-power was then used to quantify functional changes in limb control across sessions. Results Repeated-measures ANOVA for peak-power revealed a main effect of session (p Conclusions Peak-power increases within the lower frequency spectrum indicates improved volitional motor control and intentionality of paretic arm movements. Such functional changes in limb acceleration represent a mechanism underlying improved motor outcomes in music-based stroke interventions. Author(s) Disclosures The authors have nothing to disclose.

The goals of this work were to study sedimentary organic matter (OM) composition and transformation since the end of the last deglaciation and to evaluate the influence of contrasting depositional conditions on these parameters. One station was located in the Lower St. Lawrence Estuary (LSLE) where the current bottom waters are hypoxic and receive terrigenous and marine OM. The other station, located in the Gulf of St. Lawrence (GSL), has more oxygenated bottom waters and almost only marine OM inputs. Analyses included enantiomers of amino acids (L and D-AA) and muramic acid that provide different markers of OM alteration state and reactivity and of bacterial contribution to OM composition and diagenesis. The markers clearly indicated the increase in OM alteration state with depth in the sediments of the LSLE and the GSL. The steady decrease in AA yields with depth confirmed the preferential degradation of AA compared to the rest of the OM. The OM in the surface sediment of the LSLE was less altered than that of the GSL and was enriched in bacterial biomass as indicated by much higher muramic acid yields. Results indicated that an important degradation of particulate organic matter occurs in the water column in the GSL, while it takes place mostly in the sediments in the LSLE. The presence of heterogeneous OM and hypoxic conditions in the LSLE likely reduce OM degradation rate in its deep water layer. However, the zone near the water-sediment interface is responsible for large variations in AA composition at both locations. A relatively new redox index, based on AA composition, was tested and appeared robust. This study highlights the importance of ambient conditions in determining the fate of OM and in the biogeochemical cycles of vital elements.

While younger and older adults can perform upper-limb reaches to spatial targets with comparable endpoint accuracy (i.e., Helsen et al., 2016; Goodman et al., 2020), movement planning (i.e., reaction time) is significantly longer in older versus younger adults (e.g., Pohl et al., 1996; Goodman et al., 2020). Critically relevant to the current study, age-related differences in reaction time are even greater when older adults plan movement towards somatosensory versus visual or bimodal targets in the absence of vision of the moving limb (e.g., Goodman et al., 2020). One proposed explanation of these lengthened reaction times to somatosensory targets is that older adults may be experiencing challenges in implementing sensorimotor transformations when planning discrete movements of their unseen limb. To test this idea and assess the contributions of somatosensory information to these motor planning processes, tendon vibration was applied to the muscles of the effector limb between reaching movements made towards visual, somatosensory, or bimodal targets. The results revealed that older adults show the greatest increases in reaction times when vibration was applied during the preparation of movements to somatosensory targets. Further, both older and younger adults exhibited decreased movement endpoint precision when tendon vibration was applied. However, only older adults showed significantly lower movement endpoint precision due to tendon vibration when making movements to somatosensory targets, versus both visual and bimodal targets. These results corroborate previous evidence that older adults have difficulties planning upper-limb movements to somatosensory targets. As well, these results yielded novel evidence that such motor planning processes in older adult rely on somatosensory cues from the effector limb.

Amino acids (AA), including the bacterial D-enantiomers (D-AA), and bacterial muramic acid were quantified in bulk particulate and dissolved organic matter (POM and DOM) from the St. Lawrence system (Canada). These tools were used to reveal the origin of POM and DOM and their mechanisms of formation and transformation across the sediment-water interface. Results show that pore waters were much more enriched in DOM and AA (6 to 25 times) than deep waters. Pore waters are thus a source of DOM and AA (e.g., in proteins, peptides) to the sediment-water interface. AA represented 1.4 to 6.6% of bulk DOC in pore waters and thus most of the DOM compounds diffusing out of the sediments do not contain AA. Estimated AA pore water fluxes were between 32 and 141 μmol C m −2d−1 with lower values at the downstream locations. The correlations measured between AA concentrations in pore waters and deep waters, the compositional similarities between pore water DOM and deep-water DOM and their relatively altered state (measured with different diagenetic markers) suggest that a large fraction of the DOM released from the pore waters, including some AA-containing compounds, is not rapidly mineralized in the water column. Pore water DOM and deep-water DOM were the two sample types having the most similar composition when 31 parameters were considered. This similarity steadily increases downstream. Local conditions, such as POM inputs, redox conditions , and sediment mineralogy , seem to control the sediment's capacity for producing pore water AA and DOM. The C-normalized yields of the specific bacterial biomarkers and the correlations with AA yields suggest that bacteria are the major contributors to AA and to changes in POM and pore water DOM composition. In addition to the direct diffusion of altered and recalcitrant DOM out of the sediment, pore waters also provide less altered compounds, such as AA-containing structures, that can survive in the water column when the conditions are unfavorable to degradation (e.g., hypoxia) or be transformed into more recalcitrant DOM. This study suggests, based on different molecular and bulk parameters, that sediments have an important impact on the concentration and composition of the DOM persisting in deep waters.

Microbial electrosynthesis (MES) and other bioprocesses such as syngas fermentation developed for energy storage and the conversion of carbon dioxide into valuable chemicals often employs acetogens as microbial catalysts. Acetogens are sensitive to molecular oxygen, which means that bioproduction reactors must be maintained under strict anaerobic conditions. This requirement increases cost and does not eliminate the possibility of O2 leakage. For MES, the risk is even greater since the system generates O2 when water splitting is the anodic reaction. Here, we show that O2 from the anode of a MES reactor diffuses into the cathode chamber where strict anaerobes reduce CO2. To overcome this drawback, a stepwise adaptive laboratory evolution (ALE) strategy is used to develop the O2 tolerance of the acetogen Sporomusa ovata. Two heavily-mutated S. ovata strains growing well autotrophically in the presence of 0.5 to 5% O2 were obtained. The adapted strains were more performant in the MES system than the wild type converting electrical energy and CO2 into acetate 1.5 fold faster. This study shows that the O2 tolerance of acetogens can be increased, which leads to improvement of the performance and robustness of energy-storage bioprocesses such as MES where O2 is an inhibitor.

The biological reduction of CO 2 into multicarbon chemicals can be driven by electrons derived from the cathode of a bioelectrochemical reactor via microbial electrosynthesis (MES). To increase MES productivity, conditions for optimal electron transfer between the cathode and the microbial catalyst must be implemented. Here, we report the development of a 3D-graphene functionalized carbon felt composite cathode enabling faster electron transfer to the microbial catalyst Sporomusa ovata in a MES reactor. Modification with 3D-graphene network increased the electrosynthesis rate of acetate from CO 2 by 6.8 fold. It also significantly improved biofilm density and current consumption. A 2-fold increase in specific surface area of the 3D-graphene/carbon felt composite cathode explained in part the formation of more substantial biofilms compared to untreated control. Furthermore, in cyclic voltammetry analysis, 3D-graphene/carbon felt composite cathode exhibited higher current response. The results indicate that the development of a 3D-network cathode is an effective approach to improve microbe-electrode interactions leading to productive MES systems.

Microbial contribution to the maintenance and turnover of soil organic matter is significant. Yet, we do not have a thorough understanding of how biochemical composition of soil microbial biomass is related to carbon turnover and persistence of different microbial components. Using a suite of state-of-the-art analytical techniques, we investigated the molecular characteristics of extractable microbial biomass and linked it to its carbon turnover time. A 13CO2 plant pulse labelling experiment was used to trace plant carbon into rhizosphere soil microbial biomass, which was obtained by chloroform fumigation extraction (CFE). 13C content in molecular size classes of extracted microbial compounds was analysed using size exclusion chromatography (SEC) coupled online to high performance liquid chromatography–isotope ratio mass spectrometry (SEC-HPLC-IRMS). Molecular characterization of microbial compounds was performed using complementary approaches, namely SEC-HPLC coupled to Fourier transform infrared spectroscopy (SEC-HPLC-FTIR) and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). SEC-HPLC-FTIR suggests that mid to high molecular weight (MW) microbial compounds were richer in aliphatic CH bonds, carbohydrate-like compounds and possibly Pdouble bond; length as m-dashO derivatives from phospholipids. On the contrary, the lower size range was characterized by more oxidised compounds with hydroxyl, carbonyl, ether and/or carboxyl groups. ESI-FT-ICR-MS suggests that microbial compounds were largely aliphatic and richer in N than the background detrital material. Both molecular characterization tools suggest that CFE derived microbial biomass was largely lipid, carbohydrate and protein derived. SEC-HPLC-IRMS analysis revealed that 13C enrichment decreased with increasing MW of microbial compounds and the turnover time was deduced as 12.8 ± 0.6, 18.5 ± 0.6 and 22.9 ± 0.7 days for low, mid and high MW size classes, respectively. We conclude that low MW compounds represent the rapidly turned-over metabolite fraction of extractable soil microbial biomass consisting of organic acids, alcohols, amino acids and sugars; whereas, larger structural compounds are part of the cell envelope (likely membrane lipids, proteins or polysaccharides) with a much lower renewal rate. This relation of microbial carbon turnover to its molecular size, structure and composition thus highlights the significance of cellular biochemistry in determining the microbial contribution to soil carbon cycling and specifically soil organic matter formation.

Particulate photocatalysts developed for the solar energy-driven reduction of the greenhouse gas CO2 have a small product range and low specificity. Hybrid photosynthesis expands the number of products with photocatalysts harvesting sunlight and transferring charges to microbes harboring versatile metabolisms for bioproduction. Besides CO2, abiotic photocatalysts have been employed to increase microbial production yields of reduced compounds from organic carbon substrates. Most single-reactor hybrid photosynthesis systems comprise CdS assembled in situ by microbial activity. This approach limits optimization of the morphology, crystal structure, and crystallinity of CdS for higher performance, which is usually done via synthesis methods incompatible with life. Here, shape and activity optimized CdS nanorods were hydrothermally produced and subsequently applied to Cupriavidus necator for the heterotrophic and autotrophic production of the bioplastic polyhydroxybutyrate (PHB). C. necator with CdS NR under light produced 1.5 times more PHB when compared to the same bacterium with suboptimal commercially-available CdS. Illuminated C. necator with CdS NR synthesized 1.41 g PHB from fructose over 120 h and 28 mg PHB from CO2 over 48 h. Interestingly, the beneficial effect of CdS NR was specific to C. necator as the metabolism of other microbes often employed for bioproduction including yeast and bacteria was negatively impacted. These results demonstrate that hybrid photosynthesis is more productive when the photocatalyst characteristics are optimized via a separated synthesis process prior to being coupled with microbes. Furthermore, bioproduction improvement by CdS-based photocatalyst requires specific microbial species highlighting the importance of screening efforts for the development of performant hybrid photosynthesis.

Hexavalent chromium (Cr(VI)) is a carcinogenic compound that can be removed from contaminated sites by the activity of metal-reducing bacteria. The model bacterium Geobacter sulfurreducens reduces Cr(VI) to less toxic Cr(III) and accumulates Cr ions intracellularly. However, this process is usually slow with small concentrations of Cr(VI) removed in a matter of days. Here, high-density G. sulfurreducens cultures were tested for the capacity to remove Cr(VI) readily. With an initial G. sulfurreducens density of 5.8 × 108 cells ml−1, 99.0 ± 0.8% of 100 mg l−1 Cr(VI) was removed after 20 min. With a higher starting Cr(VI) concentration of 200 mg l−1, G. sulfurreducens with a density of 11.4 × 108 cells ml−1 removed 99.0 ± 0.4% Cr(VI) after 2 h. Experiments performed with cell-free spent medium indicate that extracellular proteins are major contributors for the reduction of Cr(VI) to Cr(III). Furthermore, results show that most Cr(III) ions ultimately end up inside the bacterial cells where they are less susceptible to re-oxidation. The fast Cr(VI) removal rates observed with high-density G. sulfurreducens demonstrate the potential of this bacterium for bioremediation applications such as the cleaning of industrial wastewaters.

The conversion of sunlight into H2 by noble-metal-free photocatalysts is a promising approach for the production of easy-to-store chemical energy. For this purpose, higher efficiency is achieved by photocatalysts with heterojunctions preventing fast charge recombination. Most processes for the synthesis of high-performance heterojunction photocatalysts require solvents harmful to living organisms. Here, berry-shaped (b)-CdS/MoS2 particles were fabricated instead by a hydrothermal process where non-toxic bacterial cellulose was used to mold b-CdS into nanostructures with enhanced spatial arrangement. Subsequently, MoS2 was combined with b-CdS resulting in a composite with suitable shape and intimate semiconductor contacts beneficial for charge transfer. The photocatalytic H2 evolution (PHE) of b-CdS/1%MoS2 was 63.59 mmol g-1 h-1. It was 61.1 times, 397 times, and 10.2 times higher than PHE with b-CdS, CdS fabricated without BC scaffold, and b-CdS doped with Pt, respectively. These results show the high potential of b-CdS/MoS2 and the associated synthesis method for PHE.

Summary Graphene materials (GMs) are being investigated for multiple microbiological applications because of their unique physicochemical characteristics including high electrical conductivity, large specific surface area, and robust mechanical strength. In the last decade, studies on the interaction of GMs with bacterial cells appear conflicting. On one side, GMs have been developed to promote the proliferation of electroactive bacteria on the surface of electrodes in bioelectrochemical systems or to accelerate interspecies electron transfer during anaerobic digestion. On the other side, GMs with antibacterial properties have been synthesized to prevent biofilm formation on membranes for water treatment, on medical equipment, and on tissue engineering scaffolds. In this review, we discuss the mechanisms and factors determining the positive or negative impact of GMs on bacteria. Furthermore, we examine the bacterial growth-promoting and antibacterial applications of GMs and debate their practicability., Graphical Abstract, Surface Property; Microbiology; Microbiofilms

Rapid motor learning may occur in situations where individuals perceive a threat if they do not perform a task well. This rapid motor learning may be facilitated by improved motor performance and, consequently, more errorless practice. As a first step towards understanding the role of perceived threat on rapid motor learning, the purpose of this study was to determine how performance of a motor task is affected in situations where perceived threat is high. We hypothesized that perceived threat in a virtual environment would result in improved performance of a walking task (i.e., walking on a narrow beam). Results demonstrated that increased perceived threat did not yield statistically significantly greater balance performance in the high-threat virtual environment (median percentage of successful steps: 78.8%, 48.3%, and 55.2% in the real low-threat, virtual low-threat, and virtual high-threat environments, respectively). These results may be partially attributed to habituation to threat over time and practice. If implemented carefully, virtual reality technology can be an effective tool for investigating walking balance in environments that are perceived as threatening.

The selectivity of electrochemical reduction of CO2 to formate in an aqueous NaHCO3 solution was investigated with a series of trimetallic electrodes composed of different weight percentages of Sn Co coated on copper foam (Cu-f). The maximum Faradaic efficiency of 72.2% was obtained with a Sn95-Co5/Cu-f electrode at a potential of −1.36 V. The Sn95-Co5/Cu-f electrode has a formate production rate of 1.12 mmol h−1, which is 16.7, 1.2, and 2.3 times higher than uncoated Cu-f, Cu-f coated with Sn, and Cu-f coated with Co, respectively. Analysis of the surface of the Sn95-Co5/Cu-f electrode shows the formation of a composite layer of SnOx and Co3O4 ensuring good electrical conductivity and CO2 absorption. These results in combination with linear sweep voltammetry indicate that the coating of Sn Co on a porous copper scaffold resulted in the fabrication of a promising electrochemical catalyst, which can greatly increase the electrocatalysis selectivity for CO2 reduction to formate.

Long-term cognitive deficits are observed after treatment of brain tumors or metastases by radiotherapy. Treatment optimization thus requires a better understanding of the effects of radiotherapy on specific brain regions, according to their sensitivity and interconnectivity. In the present study, behavioral tests supported by immunohistology and magnetic resonance imaging provided a consistent picture of the persistent neurocognitive decline and neuroinflammation after the onset of irradiation-induced necrosis in the right primary somatosensory cortex of Fischer rats. Necrosis surrounded by neovascularization was first detected 54 days after irradiation and then spread to 110 days in the primary motor cortex, primary somatosensory region, striatum and right ventricle, resulting in fiber bundle disruption and demyelination in the corpus callosum of the right hemisphere. These structural damages translated into selective behavioral changes including spatial memory loss, disinhibition of anxiety-like behaviors, hyperactivity and pain hypersensitivity, but no significant alteration in motor coordination and grip strength abilities. Concomitantly, activated microglia and reactive astrocytes, accompanied by infiltration of leukocytes (CD45+) and T-cells (CD3+) cooperated to shape the neuroinflammation response. Overall, our study suggests that the slow and gradual onset of cellular damage would allow adaptation in brain regions that are susceptible to neuronal plasticity; while other cerebral structures that do not have this capacity would be more affected. The planning of radiotherapy, adjusted to the sensitivity and adaptability of brain structures, could therefore preserve certain neurocognitive functions; while higher doses of radiation could be delivered to brain areas that can better adapt to this treatment. In addition, strategies to block early post-radiation events need to be explored to prevent the development of long-term cognitive dysfunction.

Adam, Mol, Pratt, and Fischer (2006) reported what they termed “a violation of Fitts’s Law” – when participants aimed to targets in an array, movement times (MTs) to the last target location (highest index of difficulty (ID)) were shorter than predicted by Fitts’s Law. Based on the results of subsequent studies in which placeholders were present either during planning and/or execution stages of the movements, it was suggested that the violation may emerge because of context-dependent changes in planning processes. The present study examined this planning explanation by conducting detailed kinematic analyses of movements. Participants performed aiming movements to sets of 3 targets in different placeholder arrays with different movement amplitudes. Consistent with previous Fitts’s Law violation findings, MTs were not significantly longer for movements to the last versus middle target location. Interestingly, the pattern of peak limb velocities (typically associated with planning processes) did not mirror the changes in MTs. On the other hand, analyses of the effector’s spatial variability during the movement suggested greater involvement of online control processes when the target was in the last position. Based on these results, we suggest that the Fitts’ Law violation observed here occurred because of more efficient online control processes.

Ideomotor theory states that the neural codes that represent action and the perceptual consequences of those actions are tightly bound in a common code. For action imagination, bound action, and perceptual codes are thought to be internally activated at a sub-threshold level through action simulation. In support of this hypothesis, previous research revealed that imagined movement times (MTs) for reciprocal aiming movements were closer to actual execution MTs after the participants gained experience executing the task. The current study examined the task-specific nature of the effects of experience on imagination by determining if improvements in accuracy in the imagination of reciprocal aiming movements occur only with experience of the reciprocal aiming task or with any aiming task. To this end, one group of participants executed a reciprocal pointing task, whereas a second group executed a discrete aiming task with comparable accuracy requirements before and after imagining reciprocal aiming movements. Influence of task specificity on imagination was assessed by evaluating the changes in imagined MTs before and after execution. Consistent with previous findings, there was a reduction in imagined MTs following task execution. Critically, there was a significant time by group interaction revealing a significant pre/post reduction in imagined MTs for the group that executed the reciprocal aiming movements, but not for the group that executed the discrete aiming movements. These data support ideomotor accounts of action imagination because it appears that the imagination of a movement is affected by task-specific experience with that movement.

Humans can perform, perceive, and imagine voluntary movement. Numerous investigations of these abilities have employed variants of goal-directed aiming tasks because the Fitts's law equation reliably captures the mathematical relationship between movement time (MT) and accuracy requirements. The emergence of Fitts's speed-accuracy relationship during movement execution, perception, and imagination has led to the suggestion that these processes rely on common neural codes. This common coding account is based on the notion that the neural codes used to generate an action are tightly bound to the codes that represent the perceptual consequences of that action. It is suggested that during action imagination and perception the bound codes are activated offline through an action simulation. The present study provided a comprehensive testing of this common coding hypothesis by examining the characteristics of the Fitts relationship in movement execution, perception, and imagination within the same individuals. Participants were required to imagine and perceive reciprocal aiming movements with varying accuracy requirements before and after actually executing the movements. Consistent with the common coding account, the Fitts relationship was observed in all conditions. Critically, the slopes of the regression lines across tasks were not different suggesting that the core of the speed-accuracy trade-off was consistent across conditions. In addition, it was found that incidental limb position variability scaled to the amplitude of imagined movements. This motor overflow suggests motor system activation during action imagination. Overall, the results support the hypothesis that action execution, perception, and imagination rely on a common coding system.

According to action-centred models of attention, there is a tight coupling between attention and response planning processes. In support of these models, previous research has shown that reach trajectories deviate towards a cue at short (100ms) cue-target onset asynchronies (CTOAs) and away from a cue presented at longer CTOAs (750ms). These deviations resemble the pattern of facilitatory and inhibitory reaction time (RT) effects observed in keypress studies. Here, participants reached to targets following a non-predictive cue and 5 CTOAs (from 100 to 600ms in 125ms intervals) were used to gain a deeper understanding of the relationship between RT and trajectory effects. Consistent with action-centred attention, facilitatory and inhibitory cuing after-effects were present in RTs and trajectories. Interestingly, RT and trajectory effects were temporally staggered: facilitatory effects were present in trajectories at the 100ms CTOA when they had already dissipated in RTs, and inhibitory effects were present in RTs (≥350ms CTOAs) before they were detected in trajectories (600ms CTOA). The time courses of the cuing effects suggest that, although action and attention systems are tightly coupled, the facilitatory and inhibitory mechanisms operate in attention before affecting action planning.

Despite decades of study, it is still unclear whether regional brain glucose uptake is lower in the cognitively healthy elderly. Whether regional brain uptake of ketones (β-hydroxybutyrate and acetoacetate [AcAc]), the main alternative brain fuel to glucose, changes with age is unknown. We used a sequential, dual tracer positron emission tomography (PET) protocol to quantify brain (18)F-fluorodeoxyglucose ((18)F-FDG) and (11)C-AcAc uptake in two studies with healthy, male Sprague-Dawley rats: (i) Aged (21 months; 21M) versus young (4 months; 4M) rats, and (ii) The effect of a 14 day high-fat ketogenic diet (KD) on brain (18)F-FDG and (11)C-AcAc uptake in 24 month old rats (24M). Similar whole brain volumes assessed by magnetic resonance imaging, were observed in aged 21M versus 4M rats, but the lateral ventricles were 30% larger in the 21M rats (p=0.001). Whole brain cerebral metabolic rates of AcAc (CMR(AcAc)) and glucose (CMR(glc)) did not differ between 21M and 4M rats, but were 28% and 44% higher, respectively, in 24M-KD compared to 24M rats. The region-to-whole brain ratio of CMR(glc) was 37-41% lower in the cortex and 40-45% lower in the cerebellum compared to CMR(AcAc) in 4M and 21M rats. We conclude that a quantitative measure of uptake of the brain's two principal exogenous fuels was generally similar in healthy aged and young rats, that the % of distribution across brain regions differed between ketones and glucose, and that brain uptake of both fuels was stimulated by mild, experimental ketonemia.

Knowledge of the structural changes that particulate organic matter (POM) undergoes in natural systems is essential for determining its reactivity and fate. In the present study, we used advanced solid-state NMR techniques to investigate the chemical structures of sinking particulate matter collected at different depths as well as humic acids (HAs) extracted from these samples and underlying sediments from the Saguenay Fjord and the St. Lawrence Lower Estuary (Canada). Compared to bulk POM, HAs contain more non-polar alkyls, aromatics, and aromatic C–O, but less carbohydrates (or carbohydrate-like structures). In the two locations studied, the C and N contents of the samples (POM and HAs) decreased with depth and after deposition onto sediments, leaving N-poor but O-enriched HAs and suggesting the involvement of partial oxidation reactions during POM microbial degradation. Advanced NMR techniques revealed that, compared to the water-column HAs, sedimentary HAs contained more protonated aromatics, non-protonated aromatics, aromatic C–O, carbohydrates (excluding anomerics), anomerics, OC q , O–C q –O, OCH, and OCH 3 groups, but less non-polar alkyls, NCH, and mobile CH 2 groups. These results are consistent with the relatively high reactivity of lipids and proteins or peptides. In contrast, carbohydrate-like structures were selectively preserved and appeared to be involved in substitution and copolymerization reactions. Some of these trends support the selective degradation (or selective preservation) theory. The results provide insights into mechanisms that likely contribute to the preservation of POM and the formation of molecules that escape characterization by traditional methods. Despite the depletion of non-polar alkyls with depth in HAs, a significant portion of their general structure survived and can be assigned to a model phospholipid. In addition, little changes in the connectivities of different functional groups were observed. Substituted and copolymerized carbohydrates and fused-ring aromatics detected in the present study likely represented an important part of molecularly uncharacterized components (MUC).

The goal of this work was to evaluate the capability of mid-infrared diffuse reflectance (DRIFT) spectroscopy, coupled with multivariate chemometric analysis, to rapidly provide valuable information on sediment composition and organic geochemistry. A large (150) and heterogeneous set of estuarine sediments was analyzed in their natural matrix by DRIFT. Principal component analysis (PCA) of DRIFT spectra clearly discriminated sediments from distinct deposition events, such as landslides or floods, based on their higher carbonate contents. PCA also distinguished mostly terrigenous sediments, enriched in organic matter, aromatics and SiO 2 , from mostly marine sediments, enriched in clays and carbonates. Partial least-squares (PLS) regression of the DRIFT spectra was used to predict various sediment properties, without the extractions or alterations required by traditional analytical methods. The relative errors in quantifying properties, as expressed by the relative root-mean-squared error (%RMSE), were ~ 6% for total humic substance and humin content, 7.6% for %C, 11.5% for atomic N:C ratio, and 13–14% for %N, %C as humic substances and %C as humin. The study revealed the importance of using a calibration sample set that is representative of the samples to be quantified. This calibration can then be used for the future and rapid analyses of unknown samples. Geochemical processes could also be inferred from band assignments of the loadings of the PLS models. These loadings indicated that nitrogen, humin (%C as humin), and aluminosilicate contents were correlated, providing independent evidence that nitrogen-rich compounds are important bonding agents between the organic and mineral fractions of the sediments. DRIFT-PCA and DRIFT-PLS represent valuable techniques for a rapid and cost-effective screening of sediment core characteristics and for an evaluation of sediment complex composition.

Amino acids and the bacterial biomarkers muramic acid and d -amino acids were quantified in the ultrafiltered dissolved, particulate and sedimentary organic matter (UDOM, POM and SOM) of the St. Lawrence system (Canada). The main objectives were to better describe the fate of terrigenous and marine organic matter (OM) in coastal zones and to quantify the bacterial contributions to OM composition and diagenesis. Regardless of their origin, the carbon (C) content of the particles substantially decreased with depth, especially near the water–sediment interface. Major diagenetic transformations of organic nitrogen (N) were revealed and important differences were observed between terrigenous and marine OM. Amino acid contents of particles decreased by 66–93% with depth and accounted for 12–30% of the particulate C losses in marine locations. These percentages were respectively 18–56% and 7–11% in the Saguenay Fjord where terrigenous input is important. A preferential removal of particulate N and amino acids with depth or during transport was measured, but only in marine locations and for N-rich particles. This leads to very low amino acid yields in deep marine POM. However, these yields then increased to a level up to three times higher after deposition on sediments, where SOM showed lower C:N ratios than deep POM. The associated increase of bacterial biomarker yields suggests an active in situ resynthesis of amino acids by benthic bacteria. The N content of the substrate most likely determines whether a preferential degradation or an enrichment of N and amino acid are observed. For N-poor OM, such as terrigenous or deep marine POM, the incorporation of exogenous N by attached bacteria can be measured, while the organic N is preferentially used or degraded in N-rich OM. Compared to the POM from the same water samples, the extracted UDOM was poor in N and amino acids and appeared to be mostly made of altered plant and bacterial fragments. Signs of in situ marine production of UDOM were observed in the most marine location. The POM entering the St. Lawrence Upper Estuary and the Saguenay Fjord appeared made of relatively fresh vascular plant OM mixed with highly altered bacterial debris from soils. In contrast, the POM samples from the more marine sites appeared mostly made of fresh planktonic and bacterial OM, although they were rapidly degraded during sinking. Based on biomarker yields, bacterial OM represented on average ∼20% of bulk C and approximately 40–70% of bulk N in POM and SOM, with the exception of deep marine POM exhibiting approximately two times lower bacterial contributions.

Examination of whole oils and isolated oil acidic fractions using Fourier transform infrared (FT-IR), negative-ion microelectrospray high-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR–MS) and gas chromatography–mass spectrometry (GC–MS) reveals significant differences in the functional groups, chemical classes and molecular weights of acidic components in crude oils derived from inland lacustrine source rocks in the Fula Sub-basin, Muglad Basin, Sudan. Correlation of the total acid number value (TAN) and bulk and molecular compositions with reservoir depth (temperature) indicates a strong influence of biodegradation on the origin of the high acidity in the oils and the possibility of distinguishing acidic compounds newly formed by way of in-reservoir biodegradation and those contributed directly from oil degrading bacteria.

Dissolved and particulate organic matters from different stations and depths in the St. Lawrence estuarine system (Canada) were collected and extracted using humic substance (HS) fractionation protocols. The origin, composition, and fate of organic matter/HS were assessed by distribution characteristics, elemental and isotopic compositions, and infrared diffuse reflectance spectroscopy (DRIFTS). HS represented over 50% of dissolved organic matter in the Saguenay Fjord's surface waters but this proportion decreased to 9–19% in the St. Lawrence Lower Estuary (SLLE). Fulvic acids were the dominant component (68–92%) of dissolved HS, especially in high salinity waters having very low humic acid content. Dissolved organic carbon (0.8–7.0 mg L − 1 ) and dissolved HS concentrations steadily decreased with downstream distance and depth. Isotopic and elemental data indicated that dissolved HS were mostly terrigenous, even in the SLLE deep waters. HS represented 62–100% of total particulate organic matter (POM) collected by sediment traps. Humin, the POM associated with the mineral matrix, was the dominant fraction of HS followed by humic acids and fulvic acids. The POM and its HS were mostly terrigenous in the fjord but mostly marine in the SLLE. Unlike its dissolved counterpart, a large part of the POM appeared to be mineralized in the water-column, even at relatively shallow ( − 2 y − 1 was lost during sinking and shortly after deposition, corresponding to an O 2 demand of more than 360 μmolO 2 cm − 2 y − 1 assuming aerobic respiration. Distribution profiles indicated a rapid particulate HS removal during sinking (16–29%) and at the water–sediment interface (up to 70% total removal). These losses were especially important for N-containing molecules, aliphatic components, and marine non-humic POM. In contrast, humin was the most stable fraction. The interactions between POM and the mineral matrix appeared mediated by carboxylate groups. Differences in the composition of dissolved HS and particulate HS may explain their contrasting reactivities. Dissolved HS were nitrogen-poor, more oxidized, and depleted in aliphatic structures as compared to POM. The aliphatic content of dissolved and particulate HS was greater in marine samples (downstream) and decreased during diagenesis. The proportion of CH 3 groups relative to CH 2 groups was surprisingly high in dissolved fulvic acids, an important fraction of DOM. DRIFTS was particularly useful in providing information on HS structures and transformations.

Motor learning disturbances have been shown in diseases involving dopamine insufficiency such as Parkinson’s disease and schizophrenic patients under antipsychotic drug treatment. In non-human primates, motor learning deficits have also been observed following systemic administration of raclopride, a selective D2-receptor antagonist. These deficits were characterized by persistent fluctuations of performance from trial to trial, and were described as difficulties in consolidating movements following a learning period. Moreover, it has been suggested that these raclopride-induced fluctuations can result from impediments in grouping separate movements into one fluent sequence. In the present study, we explore the hypothesis that such fluctuations during movement consolidation can be prevented through the use of sumanirole – a highly selective D2 agonist – if administered before raclopride. Two monkeys were trained to execute a well known sequence of movements, which was later recalled under three pharmacological conditions: (1) no drug, (2) raclopride, and (3) sumanirole + raclopride. The same three pharmacological conditions were repeated with the two monkeys, trained this time to learn new sequences of movements. Results show that raclopride has no deleterious effect on the well known sequence, nor the sumanirole + raclopride co-administration. However, results on the new sequence to be learned revealed continuous fluctuations of performances in the raclopride condition, but not in the sumanirole + raclopride condition. These fluctuations occurred concurrently with a difficulty in merging separate movement components, known as a “chunking deficit”. D2 receptors seem therefore to be involved in the consolidation of new motor skills, and this might involve the chunking of separate movements into integrated motor sequences.

This study examined the spatial and temporal limitations of the visual corrective process in the control of upper limb movements. Real-time calculation of kinematic data was used to trigger a prismatic displacement of the movement environment during manual aiming. Using an OptoTrak motion tracking system, a data acquisition unit, and a custom-made program, perturbations were triggered at peak acceleration, peak velocity, and the estimated time of peak deceleration. Movement outcome was significantly influenced only when the visual displacement occurred at peak acceleration. The results support models of visual control that posit that early visual information is required for accurate limb control.

Detailed structural information on two humic acids extracted from two sinking particulate matter samples at a water depth of 20 m in the Saguenay Fjord (F-20-HA) and the St. Lawrence Estuary (E-20-HA) (Canada), was obtained by advanced solid-state NMR. Spectral-editing analyses provided numerous structural details rarely reported in geochemical studies. The NMR data account almost quantitatively for the elemental compositions. The two humic acids were found to be quite similar, consisting of four main structural components: peptides (ca. 39 ± 3% vs. 34 ± 3% of all C for E-20-HA and F-20-HA, respectively); aliphatic chains, 14–20 carbons long (ca. 25 ± 5% vs. 17 ± 5% of all C); aromatic structures (ca. 17 ± 2% vs. 26 ± 2% of all C); and sugar rings (14 ± 2% vs. 15 ± 2% of all C). Peptides were identified by 13 C{ 14 N} SPIDER NMR, which selects signals of carbons bonded to nitrogen, and by dipolar DEPT, which selects CH-group signals, in particular the NCH band of peptides. The SPIDER spectra also indicate that heterocycles constitute a significant fraction of the aromatic structures. The aliphatic (CH2)n chains, which are highly mobile, contain at least one double bond per two chains and end in methyl groups. 1 H spin diffusion NMR experiments showed that these mobile aliphatic chains are in close (

The concentrations of sedimentary humic substances (HS) were measured in the St. Lawrence marine system, Quebec (Canada), including the Saguenay Fjord. Concentration ranges for humin, humic acids and fulvic acids were 7–49, 1–19, and 0.5–6 mg per gram of sediment (dry weight), respectively. HS always represented the dominant component of sediment organic matter (SOM) (i.e., 52–100%) for which humin, humic acids, and fulvic acids accounted for 38–88%, 4–28%, and 2–14%, respectively. These results indicate that most HS and an important part of SOM were associated with the mineral matrix and thus defined as humin. HS concentrations varied slightly by site location and depth but major changes in concentration in the fjord were caused by episodic events such as floods and landslides. In the fjord, sedimentary HS were mostly terrigenous and molecules such as lignin likely contributed to the high proportions of HS. In the St. Lawrence Estuary, an important input of marine particulate organic matter and favorable conditions for its degradation seem to have promoted the mineralization of the labile SOM before its burial. The less labile SOM was buried in sediments where humification and stabilization appeared to occur. Such processes could explain the lower SOM concentrations but greater humin proportions with increasing distance downstream and sediment depth. Estimations based on HS profiles suggest that ∼25% of the surface SOM will be preserved in deeper layers (i.e., >1 m), principally in the form of humin. Sorption of organic matter onto mineral surfaces might have contributed to SOM preservation and humin stabilization in sediments. DRIFT spectroscopy suggests that carboxylate groups may mediate this sorption.

Microbial contributions to the detritus of two vascular plant tissues, smooth cordgrass (Spartina alterniflora) and black mangrove leaves (Avicennia germinans), were estimated over a 4-year decomposition period under subaqueous marine conditions. During this period, 93–97% of the initial plant tissues was decomposed. Bulk elemental and isotopic compositions of the detritus were measured along with hydrolyzable amino sugars (AS) and amino acids (AA), including the bacterial biomarkers muramic acid and the d -enantiomers of AA. A major enrichment in N relative to C occurred during decomposition. Net increases of AS, AA, and bacterial biomarkers in decaying detritus were observed. Three independent approaches indicated that on average 60–75% of the N and 20–40% of the C in highly decomposed detritus were not from the original plant tissues but were mostly from heterotrophic bacteria. During decomposition hydrolyzable AS + AA yields (∼54% of total N) were strongly correlated with total N in both types of detritus. The uncharacterized N appeared to have the same origin and dynamics as AA, suggesting the contribution of other bacterial biomolecules not measured here. There was little indication of humification or abiotic processes. Instead, N-immobilization appeared primarily bacterially mediated. Although varying dynamics were observed among individual molecules, bacterial detritus exhibited an average reactivity similar to plant detritus. Only a minor fraction of the bacterial detritus escaped rapid biodegradation and the relationship between bacterial activity and N-immobilization is consistent with an enzymatically mediated preservation mechanism. Bacteria and their remains are ubiquitous in all ecosystems and thus could comprise a major fraction of the preserved and uncharacterized organic matter in the environment.

The sorption of hydrophobic phenanthrene and fluoranthene on whole estuarine particulate matter and humic acid fraction was studied in batch experiments under varying conditions of temperature, salinity, and dissolved humic substances (DHS) concentrations. The use of estuarine particles and dissolved organic matter (here DHS) instead of mineral particles or synthetic organic matter represents an important contribution of this study. A decrease in water temperature and an increase in salinity, such as encountered in estuaries during the transition from river to seawater, together increased the fraction of the contaminants sorbed to the particles by 40% to 64%, on average. The sorption observed at different temperatures indicates a slightly exothermic sorption process with calculated enthalpies between −4.5 and −13.2 kJ/mol. The impact of both temperature and salinity variations can be chiefly attributed to changes in the contaminant's water solubility. The calculated isotherm parameters, sorption enthalpies and entropies are in agreement with a sorption dominated by partitioning between water and unsaturated particles. Nevertheless, these calculations also reveal a low proportion of sorption sites having higher energy (e.g., site-specific adsorption) than those involved in partitioning. The effect of DHS upon the sorption of fluoranthene onto estuarine particles was negligible or minor, depending on the DHS concentrations. Although DHS may have a relatively high affinity for the fluoranthene fraction that remains in solution after sorption, their capacity to compete with the particles during the sorption is surprisingly low. This finding cannot be predicted by the generally high DHS partition coefficients ( K DOM ) reported. The impacts of the three parameters studied upon sorption and sediment trapping may be less important than those caused by changes in the composition or in the concentration of suspended particulate matter in estuaries. This may explain why the influence of these parameters is difficult to observe in field studies.