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International audience; A high-energy ball milling of magnetite nanoparticles with amino-phosphonic functionalized poly(glycidyl methacrylate) polymer is used for manufacturing a highly efficient magnetic sorbent for U(VI) sorption from aqueous solutions. The Uranyl ions were adsorbed through the binding with amine and phosphonic groups as confirmed by Fourier Transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The maximum sorption capacity (up to 270 mg U g−1) occurred at pH = 3–4; Langmuir isotherm well describes the sorption process. Small-size particles allow achieving fast uptake (within ≈90 min of contact); and the kinetic profiles are modeled by the pseudo-second order rate equation. Uranium is successfully desorbed from loaded sorbent using 0.25 M NaHCO3 solution: Sorbent can be recycled with minimal decrease in sorption and desorption efficiency for at least 6 cycles. The sorbent is efficiently used for U(VI) recovery from the acidic leachates of U-bearing ores (after precipitation pre-treatment). Sorption capacity approaches 190 mg U g−1 despite the presence of high concentrations of Fe and Si: the sorbent has a marked preference for U(VI) (confirmed by distribution ratios and selectivity coefficients).

International audience; Thiourea-formaldehyde (TF) resin is prepared by polycondensation of its two precursors; the incorporation of pre-formed magnetite particles allows synthesizing a magnetic derivative of TF (MTF). These materials are applied to the sorption of two dyes (titan yellow, TY, and rose bengal, RB). Ultrasonic treatment (UT) is tested as an alternative to mechanical agitation (MA). The two sorbents are characterized by scanning electron microscopy, vibrating-sample magnetometry, BET surface area analysis, thermogravimetric analysis, Fourier-transform infrared and NMR spectroscopy, zetametry. Sorption properties are compared for TF and MTF under both MA and UT; considering pH effect, uptake kinetics (modeled using the pseudo-second order rate equation, and resistance to intraparticle diffusion), sorption isotherms (fitted by the Langmuir and Sips equations), the effect of competitor ions, and the desorption efficiency. Optimum sorption occurs at pH 3 (balance between (a) the electrostatic interactions between protonated groups (sorbent) and anionic forms of the dyes, and (b) the competitor effects of counter anions). UT strongly decreases the contact time required for reaching equilibrium (from 240 min to 30 min). UT increases the sorption capacities: in the range 0.3–0.6 mmol dye g−1 (MA) up to 0.9–1 mmol dye g−1. The magnetic core does not change kinetics, while it increases TF sorption capacities for both TY and RB. Under UT, the maximum sorption capacities are comparable for TF and MTF; however, the affinity of MTF remains higher than TF for the two dyes. Alkaline NaCl solutions completely desorb the dyes; UT decreases both the contact time and the NaCl concentration required for achieving the complete desorption of loaded dyes. The sorbents are recycled with high stability in sorption performance for at least five cycles.

Measurement of oxygen uptake during exercise ([Formula: see text]) is currently non-accessible to most individuals without expensive and invasive equipment. The goal of this pilot study was to estimate cycling [Formula: see text] from easy-to-obtain inputs, such as heart rate, mechanical power output, cadence and respiratory frequency. To this end, a recurrent neural network was trained from laboratory cycling data to predict [Formula: see text] values. Data were collected on 7 amateur cyclists during a graded exercise test, two arbitrary protocols (Prot-1 and -2) and an "all-out" Wingate test. In Trial-1, a neural network was trained with data from a graded exercise test, Prot-1 and Wingate, before being tested against Prot-2. In Trial-2, a neural network was trained using data from the graded exercise test, Prot-1 and 2, before being tested against the Wingate test. Two analytical models (Models 1 and 2) were used to compare the predictive performance of the neural network. Predictive performance of the neural network was high during both Trial-1 (MAE = 229(35) mlO2min-1, r = 0.94) and Trial-2 (MAE = 304(150) mlO2min-1, r = 0.89). As expected, the predictive ability of Models 1 and 2 deteriorated from Trial-1 to Trial-2. Results suggest that recurrent neural networks have the potential to predict the individual [Formula: see text] response from easy-to-obtain inputs across a wide range of cycling intensities.

HO2 radicals play important roles in tropospheric chemistry. The large discrepancies among field measurements and sophisticated model predictions for the overall HO2 concentrations can be attributed to the HO2 uptake coefficients onto ambient aerosols (γ) have not yet been properly quantified. This study presents the first online measurement of the total HO2 reactivity caused by the ambient gas phase ( k g ' ) and aerosol phase ( k a ' ) in the summer of 2018 in Kyoto, Japan, using a combined laser-flash photolysis and laser-induced fluorescence (LFP–LIF) technique coupled with a versatile aerosol concentration enrichment system (VACES) that enriches ambient aerosols. The results denote that k g ' ranged from 0.1 s−1 (25th percentile) to 0.32 s−1 (75th percentile) with an average value of 0.22 ± 0.16 s−1 (1σ), which can be primarily explained by the reaction of HO2 with NO2. With the application of VACES and the auto-switching aerosol filter, k a ' ranged from 0.004 s−1 (25th percentile) to 0.028 s−1 (75th percentile) with an average value of 0.017 ± 0.015 s−1. When converted k a ' to ambient conditions (by dividing with the enrichment factor), this result was ~10 times higher than the HO2 reactivity caused by its self-reaction under ambient concentration levels (~5 ppt) at 298 K. The related γ ranged from 0.08 (25th percentile) to 0.36 (75th percentile), with an average value of 0.24, which is comparable with the values used in previous modeling studies (~0.2); however, it presents a large variation of ±0.20 (1σ) within the measurement time. This indicates that a large bias may exist with respect to the estimation of HO2 concentrations when using a constant γ value. Further, we suggest that different γ values should be applied in modeling studies depending on the environment conditions; the γ value obtained here can be used as an upper limit value for urban areas in the summer due to possible aerosol phase changes. The analysis of ambient air backward trajectories indicates that the predominant NO2 emission sources originated from the mainland of Japan. However, no significant differences regarding HO2 uptake coefficients were observed when air masses came through the mainland or from the coastal direction. This study provides considerably reliable γ, which could increase the modeling accuracy of heterogeneous processes in tropospheric chemistry. However, combining online and offline methods appears to be more suitable for addressing the variation in γ and model discrepancies in further studies.

Skeletal muscle function in patients with heart failure and reduced ejection fraction (HFrEF) greatly determines exercise capacity. However, reports on skeletal muscle fiber dimensions, fiber capillarization, and their physiological importance are inconsistent. Twenty-five moderately impaired patients with HFrEF and 25 healthy control (HC) subjects underwent muscle biopsy sampling. Type I and type II muscle fiber characteristics were determined by immunohistochemistry. In patients with HFrEF, enzymatic oxidative capacity was assessed, and pulmonary oxygen uptake (V̇o2) and skeletal muscle oxygenation during maximal and moderate-intensity exercise were measured using near-infrared spectroscopy. While muscle fiber cross-sectional area (CSA) was not different between patients with HFrEF and HC, the percentage of type I fibers was higher in HC (46 ± 15 vs. 37 ± 12%, respectively, P = 0.041). Fiber type distribution and CSA were not different between patients in New York Heart Association (NYHA) class II and III. Type I muscle fiber capillarization was higher in HFrEF compared with HC[capillary-to-fiber perimeter exchange (CFPE) index: 5.70 ± 0.92 vs. 5.05 ± 0.82, respectively, P = 0.027]. Patients in NYHA class III had slower V̇o2 and muscle deoxygenation kinetics during onset of exercise and lower muscle oxidative capacity than those in class II ( P < 0.05). Also, fiber capillarization was lower but not compared with HC. Higher CFPE index was related to faster deoxygenation ( rspearman = −0.682, P = 0.001), however, not to muscle oxidative capacity ( r = −0.282, P = 0.216). Type I muscle fiber capillarization is higher in HFrEF compared with HC but not in patients with greater exercise impairment. Greater capillarization may positively affect V̇o2 kinetics by enhancing muscle oxygen diffusion. NEW & NOTEWORTHY The skeletal myopathy of chronic heart failure (HF) includes a greater percentage of fatigable type II fibers and, for less impaired patients, greater skeletal muscle fiber capillarization. Near-infrared spectroscopy measurements of skeletal muscle oxygenation indicate that greater capillarization may compensate for reduced blood flow in mild HF by enhancing the diffusive capacity of skeletal muscle. This thereby augments and speeds oxygen extraction during contractions, which is translated into faster pulmonary oxygen uptake kinetics.

Highly percolating membranes are prepared by the interaction of polyethylenimine and alginate (with glutaraldehyde crosslinking). SEM illustrates the macroporous structure of the material. The material is characterized by FTIR before and after chromate anions sorption. Batch-simulated continuous sorption experiments revealed that the maximum sorption occurred at pH 2 and the flow rate has limited effect on sorption efficiency. Uptake kinetics and sorption isotherms are well fitted by the pseudo-second-order rate and Sips equations, respectively. Maximum sorption is found close to 314 mg g−1. Competition effects from Ca(II), Cu(II), Cl−, NO3−, and SO42− are investigated to evaluate sorbent selectivity. The membranes are applied to remediate a simulate of Cr(VI) contaminated electroplating wastewater. Successive cycles of sorption and desorption show that the membranes maintain sorption capacity higher than 200 mg Cr g−1 for both Cr(VI) and total chromium for the first two cycles. These new highly percolating membranes have promising performances for Cr(VI) removal.

Salvianolic acid B (SAB) has a high concentration in the liver, but the mechanism of its distribution in the liver is unclear. The aim of this study was to investigate the mechanisms of hepatic uptake of SAB. In this study, we first explored the uptake features of SAB in HepG2 cells and the effect of rifampicin on uptake. Then, we explored the effects of SAB on the uptake of pitavastatin in HepG2 cells. Finally, we established an HEK239T-OATP1B1 cell model to confirm whether OATP1B1 mediated the transport of SAB. Results showed that the uptake kinetic parameters Vmax and Km for SAB in HepG2 cells were 21.28 ± 2.06 pmol mg-1 per protein min-1 and 28.47 ± 7.36 μM, respectively. Rifampicin inhibited the uptake of SAB in HepG2 cells (IC50 was 5.85 ± 1.70 μM), and SAB affected the uptake of pitavastatin in HepG2 cells (IC50 was 27.67 ± 1.90 μM). The uptake kinetic parameters Vmax and Km for SAB in HEK239T-OATP1B1 were 60.03 ± 6.16 pmol mg-1 per protein min-1 and 87.24 ± 15.28 μM, respectively, whereas in EGFP-HEK293 cells were 14.04 ± 2.53 pmol mg-1 per protein min-1 and 56.53 ± 15.50 μM. The SAB had no effect of on the expression of OATP1B1 in HEK239T-OATP1B1 cells. In conclusion, this study demonstrated that OATP1B1 contributes to the transport and accumulation of SAB in the liver.

Restoration of seagrass beds through seedlings is an alternative to the transplantation of adult plants that reduces the impact over donor areas and increases the genetic variability of restored meadows. To improve the use of Cymodocea nodosa seedlings, obtained from seeds germinated in vitro, in restoration programs, we investigated the ammonium and phosphate uptake rates of seedlings, and the synergistic effects of light levels (20 and 200 mu mol quanta m(-2) s(-1)) and different nitrogen to phosphorus molar ratios (40 mu M N:10 mu M P, 25 mu M N:25 mu M P, and 10 mu N:40 mu M P) on the photosynthetic activity and growth of seedlings. The nutrient content of seedlings was also compared to the seed nutrient reserves to assess the relative importance of external nutrient uptake for seedling development. Eighty two percent of the seeds germinated after 48 days at a mean rate of 1.5 seeds per day. All seedlings under all treatments survived and grew during the 4 weeks of the experiment. Seedlings of C. nodosa acquired ammonium and phosphate from the incubation media while still attached to the seed, at rates of about twice of adult plants. The relevance of external nutrient uptake was further highlighted by the observation that seedlings' tissues were richer in nitrogen and phosphorus than non-germinated seeds. The uptake of ammonium followed saturation kinetics with a half saturation constant of 32 mu M whereas the uptake of phosphate increased linearly with nutrient concentration within the range tested (5 - 100 mu M). Light was more important than the nutrient ratio of fertilization for the successful development of the young seedlings. The seedlings' photosynthetic and growth rates were about 20% higher in the high light treatment, whereas different nitrogen to phosphorus ratios did not significantly affect growth. The photosynthetic responses of the seedlings to changes in the light level and their capacity to use external nutrient sources showed that seedlings of C. nodosa have the ability to rapidly acclimate to the surrounding light and nutrient environment while still attached to the seeds. C. nodosa seedlings experiencing fertilization under low light levels showed slightly enhanced growth if nourished with a balanced formulation, whereas a slight increase in growth was also observed with unbalanced formulations under a higher light level. Our results highlight the importance of high light availability at the seedling restoration sites. Department of the Environment, Heritage and Climate Change of Gibraltar; FCT, the Portuguese Foundation for Science and Technology [SFRH/BPD/91629/2012]; FCT [UID/Multi/04326/2013]

Designer nanoparticles with controlled shapes and sizes are increasingly popular vehicles for therapeutic delivery due to their enhanced cell-delivery performance. However, our ability to fashion nanoparticles has offered only limited control over these parameters. Structural DNA nanotechnology has an unparalleled ability to self-assemble three-dimensional nanostructures with near-atomic resolution features, and thus, it offers an attractive platform for the systematic exploration of the parameter space relevant to nanoparticle uptake by living cells. In this study, we examined the cell uptake of a panel of 11 distinct DNA-origami shapes, with the largest dimension ranging from 50-400 nm, in 3 different cell lines. We found that larger particles with a greater compactness were preferentially internalized compared with elongated, high-aspect-ratio particles. Uptake kinetics were also found to be more cell-type-dependent than shape-dependent, with specialized endocytosing dendritic cells failing to saturate over 12 h of study. The knowledge gained in the current study furthers our understanding of how particle shape affects cellular uptake and heralds the development of DNA nanotechnologies toward the improvement of current state-of-the-art cell-delivery vehicles.

Dissolved inorganic phosphorus (DIP) is an essential macronutrient for maintaining metabolism and growth in autotrophs. Little is known about DIP uptake kinetics and internal P-storage capacity in seaweeds, such as Ulva laduca (Chlorophyta). Ulva laduca is a promising candidate for biofiltration purposes and mass commercial cultivation. We exposed U. laduca to a wide range of DIP concentrations (1-50 mu mol center dot L-1 and a nonlimiting concentration of dissolved inorganic nitrogen (DIN; 5,000 mu mol center dot L-1 ) under fully controlled laboratory conditions in a "pulse-and-chase" assay over 10 d. Uptake kinetics were standardized per surface area of U. lactual fronds. Two phases of responses to DIP-pulses were measured: (i) a surge uptake (V-s) of 0.67 +/- 0.10 mu mo] center dot cm(-2) center dot d(-1) and (ii) a steady state uptake (V-M ) of 0.07 +/- 0.03 mu mol center dot cm(-2)center dot d(-1) . Mean internal storage capacity (ISCp) of 0.73 +/- 0.13 mu mol center dot cm(-2) was calculated for DIP. DIP uptake did not affect DIN uptake. Parameters of DIN uptake were also calculated: V-s = 12.54 +/- 1.90 mu mol center dot cm(-2) center dot d(-1), V-M = 2.26 +/- 0.86 mu mol center dot cm(-2) center dot d(-1) , and ISCN = 22.90 +/- 6.99 mu mol center dot cm(-2) . Combining ISC and V-M values of P and N, nutrient storage capacity of U. lactuca was estimated to be sufficient for similar to 10 d. Both P and N storage capacities were filled within 2 d when exposed to saturating nutrient concentrations, and uptake rates declined thereafter at 90% for DIP and at 80% for DIN. Our results contribute to understanding the ecological aspects of nutrient uptake kinetics in U. lactuca and quantitatively evaluating its potential for bioremediation and/or biomass production for food, feed, and energy.

International audience; A one-pot synthesis procedure was used for preparing two derivatives of chitosan bearing α-aminophosphonate moieties. Chitosan functionalization was performed by reacting chitosan with glutaraldehyde and triphenylphosphite or trimethylphosphite under selected experimental conditions. The materials (CS-Ph and CS-Me, respectively) were characterized using different analytical procedures for confirming their suggested structures: scanning electron microscopy (coupled to energy dispersive X-ray analysis), Fourier-transform infra-red spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy analyses, thermogravimetric analysis and elemental analysis. The sorption properties of these materials were compared for U(VI) recovery through the study of pH effect, sorption isotherms, thermodynamics, uptake kinetics and sorbent recycling (metal desorption and sorbent re-use). The sorption isotherms were modeled using the Langmuir and the Sips equations while the kinetic profiles were preferentially fitted by the pseudo-second order rate equation. The comparison of sorption properties shows that the methyl α-aminophosphonate derivative is much more effective in uranium recovery than the phenyl derivative: maximum sorption capacities reached at pH 5 around 245 mg U g−1 and 114 mg U g−1, respectively. Tentative explanations are suggested associated to the acid-base properties, the steric hindrance and the donor/acceptor behavior of reactive groups. Experimental data show that uranyl sorption process proceeds via an exothermic and spontaneous reaction for the two sorbents. Metal desorption was successfully tested using sodium bicarbonate solutions and the sorbent was recycled four times: the sorption and desorption efficiencies progressively decreased but remained relatively high at the fourth cycle (sorption: 88–90% of initial sorption and desorption decreasing by 5% between the first and the fourth cycles). Finally, the sorbents were efficiently tested on acidic ore leachate.

Dissolved inorganic phosphorus (DIP) is an essential macronutrient for maintaining metabolism and growth in autotrophs. Little is known about DIP uptake kinetics and internal P-storage capacity in seaweeds, such as Ulva laduca (Chlorophyta). Ulva laduca is a promising candidate for biofiltration purposes and mass commercial cultivation. We exposed U. laduca to a wide range of DIP concentrations (1-50 mu mol center dot L-1 and a nonlimiting concentration of dissolved inorganic nitrogen (DIN; 5,000 mu mol center dot L-1 ) under fully controlled laboratory conditions in a "pulse-and-chase" assay over 10 d. Uptake kinetics were standardized per surface area of U. lactual fronds. Two phases of responses to DIP-pulses were measured: (i) a surge uptake (V-s) of 0.67 +/- 0.10 mu mo] center dot cm(-2) center dot d(-1) and (ii) a steady state uptake (V-M ) of 0.07 +/- 0.03 mu mol center dot cm(-2)center dot d(-1) . Mean internal storage capacity (ISCp) of 0.73 +/- 0.13 mu mol center dot cm(-2) was calculated for DIP. DIP uptake did not affect DIN uptake. Parameters of DIN uptake were also calculated: V-s = 12.54 +/- 1.90 mu mol center dot cm(-2) center dot d(-1), V-M = 2.26 +/- 0.86 mu mol center dot cm(-2) center dot d(-1) , and ISCN = 22.90 +/- 6.99 mu mol center dot cm(-2) . Combining ISC and V-M values of P and N, nutrient storage capacity of U. lactuca was estimated to be sufficient for similar to 10 d. Both P and N storage capacities were filled within 2 d when exposed to saturating nutrient concentrations, and uptake rates declined thereafter at 90% for DIP and at 80% for DIN. Our results contribute to understanding the ecological aspects of nutrient uptake kinetics in U. lactuca and quantitatively evaluating its potential for bioremediation and/or biomass production for food, feed, and energy.

International audience; BACKGROUND: The nuclear power industry and other high‐tech industries require increasing quantities of uranium and rare‐earth elements (REEs). There is a need for materials that can competitively recover these metals from ore leachates (such as produced in the leaching of Egyptian ores).RESULTS : A sorbent based on the chemical grafting of glutamine moieties on a magnetic polyacrylonitrile support was synthesized: polyacrylonitrile, crosslinked with 10% divinyl benzene in the presence of magnetite, was chemically modified by a series of grafting steps to produce a magnetic polyglutamine sorbent (MGLU). The sorbent was characterized by titration, elemental analysis, X‐ray diffraction (XRD), thermogravimetric analysis, Fourier‐transform infra‐red (FTIR) spectrometry and scanning electron microscopy (SEM). The sorption properties were tested as a function of pH; the sorption isotherms were modeled using the Langmuir equation (maximum sorption capacities: 2 mmol U g‐1 and up to 3.5 mmol g‐1 for Nd(III) and Dy(III)). The equilibrium is achieved within 1 h of contact. Metal desorption and sorbent recycling are highly efficient using acidic solutions; sorption/desorption performance remains stable for a minimum of 5 cycles. MGLU was tested for metal binding in multi‐metal solutions at different pH values. CONCLUSION: This sorbent could be used for the recovery of REEs and uranium from simulated ore leachates.

International audience; A composite material (PAN-Na-Y-zeolite) was prepared by polymerization of acrylonitrile in the presence of Na-Y zeolite. The A composite was functionalized by amidoximation through the reaction of hydroxylamine on nitrile groups of the composite. The sorbent (APNa-Y-zeolite) was fully characterized by FTIR spectrometry, XRD diffraction, thermogravimetric analysis, scanning electron microscopy, zetametry and BET analysis. The sorption properties of APNa-Y-zeolite were investigated for the recovery of Cu(II), Cd(II) and Pb(II) from synthetic solutions before being tested for the purification of local tap water. Sorption properties were characterized through the study of pH effect, uptake kinetics, sorption isotherms. The pseudo-second order rate equation fitted well kinetic profiles. Sorption isotherms were modeled using the Langmuir, the Freundlich and the Sips equations. Thermodynamic parameters were evaluated through variation of temperature. While the sorption of Cu(II) and Cd(II) was endothermic, Pb(II) recovery was exothermic. Metal ions were successfully desorbed using 5 M HCl solutions. High concentrations of NaCl hardly alter sorption performance, contrary to humic acid that slightly reduces metal binding.

Dietary phenolic compounds are often transformed by gut microbiota prior to absorption. This transformation may modulate their biological activities. Many fundamental questions still need to be addressed to understand how the gut microbiota-diet interactions affect human health. Herein, a UHPLC-QTOF mass spectrometry-based method for the quantification of uptake and determination of intracellular bacterial concentrations of dietary phenolics from coffee and tea was developed. Quantitative uptake data for selected single purified phenolics were determined. The specific uptake from mixtures containing up to four dietary relevant compounds was investigated to assess changes of uptake parameters in a mixture model system. Indeed, perturbation of bacteria by several compounds alters uptake parameter in particular tmax. Finally, model bacteria were dosed with complex dietary mixtures such as diluted tea or coffee extracts. The uptake kinetics of the twenty most abundant phenolics was quantified and the findings are discussed. For the first time, quantitative data on in-vitro uptake of dietary phenolics from food matrices were obtained indicating a time-dependent differential uptake of nutritional compounds.

There is limited study to simultaneously determine the relative bioavailability of heavy metals such as Cd, Pb, Cu, Cr(VI), and Ni in soil samples. In the present study, the bioaccessibility of heavy metals using in vitro assay was compared with the relative bioavailability of heavy metals using in vivo mouse model. The bioaccessibility of heavy metals ranged from 9.05 ± 0.97 % (Cr) to 42.8 ± 3.52 % (Cd). The uptake profile of heavy metals in soil and solution samples in mouse revealed that the uptake kinetics could be fitted to a two-compartment model. The relative bioavailability of heavy meals ranged from 34.8 ± 7.0 % (Ni) to 131 ± 20.3 % (Cu). Poor correlation between bioaccessibility and relative bioavailability of heavy metals was observed (r (2) = 0.11, p > 0.05). The relative bioavailability of heavy metals was significantly higher than the bioaccessibility of heavy metals (p

Given the importance of the watershed protection plans, direct determination of phosphorus (P) mineralization rates in advanced wastewater treatment facility effluents is crucial for developing the most protective strategies minimiz eutrophication in receiving surface waters. In this study, algal bioassays were used to determine the uptake rate of dissolved P in effluents from a broad range of advanced nutrient removal technologies (e.g., membrane biological reactor, traditional biological, tertiary membrane, Blue PRO™, etc.). Dissolved P uptake kinetics were fit to a gamma model and three first-order decay models. A traditional one-pool model correlated poorly with the experimental data (i.e., r2 = 0.73 ± 0.09), whereas two-pool model and three-pool models performed much better (i.e., r2 > 0.9). These models also provided strong evidence for the existence of recalcitrant P in the effluents from these tertiary facilities. The Gamma model showed the mineralization of organic P followed a reactive continuum and further suggested the partitioning of P loads with different bioavailability levels should be accounted for the future modeling practices. From a modeling perspective, the Gamma model should be considered to be the theoretically best model as it gave the most parsimonious fit to the data using the fewest terms. Our study suggested that the current Total Maximum Daily Load (TMDL) model could be easily modified with the updated mineralization kinetics, which should lead to both ecological and economic benefits.

Fast scan cyclic voltammetry is commonly used for measuring the kinetics of dopamine release and uptake. For experiments using an anesthetized preparation, urethane is preferentially used because it does not alter dopamine uptake kinetics compared to freely moving animals. Unfortunately, urethane is highly toxic, can induce premature death during experiments, and cannot be used for recovery surgeries. Isoflurane is an alternative anesthetic that is less toxic than urethane, produces a stable level of anesthesia over extended periods, and is often used for recovery surgeries. Despite these benefits, the effects of isoflurane on dopamine release and uptake have not been directly characterized. In the present studies, we assessed the utility of isoflurane for voltammetry experiments by testing dopamine signaling parameters under baseline conditions, after treatment with the dopamine uptake inhibitor cocaine, and after exposure to increasing concentrations of isoflurane. Our results indicate that surgical levels of isoflurane do not significantly alter terminal mechanisms of dopamine release and uptake over prolonged periods of time. Consequently, we propose that isoflurane is an acceptable anesthetic for voltammetry experiments, which in turn permits the design of studies in which dopamine signaling is examined under anesthesia prior to recovery and subsequent experimentation in the same animals.

Plant uptake rates of nitrate and potassium (K) are under feedback control from plant concentrations of nitrogen (N) and K, respectively. However, there is uncertainty concerning the interactions between nitrate and K uptake. We tested the hypothesis that plant concentrations of N affect K uptake and plant concentrations of K affect uptake rates of nitrate. Two experiments were carried out with wheat. Each consisted of three phases. In Phase 1, the plants were grown in complete nutrient solution for 17–18 days. In Phase 2, nitrate and K treatments were imposed – the plants were either starved of the nutrient or provided excess for 2.5 or 5 days. This generated plants of similar size but with different N and K concentrations. In Phase 3, complete nutrient solutions were restored for all plants and nitrate and K uptake was followed for 8 h. Uptake till the end of Phases 2 and 3 was examined by analysis of variance. Uptake during Phase 3 was also examined using a simple model that included Michaelis-Menten uptake kinetics and feedback control due to whole-plant N and K concentrations, but assumed no interaction between nitrate and K uptake. The model was fitted using Phase 3 measurements of nitrate uptake following nitrate starvation or excess and K uptake following K starvation or excess. There was little influence of plant N on K uptake or of plant K on nitrate uptake for periods that started with adequate plant concentrations of N and K (Phases 1 and 2). However, in Phase 3 when N starvation was broken, the plants took up more K than controls and model predictions, so feedback control of K uptake had been lessened. Similarly, when K starvation was broken, feedback control of nitrate uptake was lessened. If plants had endured both N and K starvation then on release of that they took up more K but less nitrate than predicted by the model. These results support the hypothesis under test, and suggest interactions between the mechanisms that regulate uptake of nitrate and K.

We tested the hypothesis that inorganic nitrate (NO3−) supplementation would improve muscle oxygenation, pulmonary oxygen uptake (V̇o2) kinetics, and exercise tolerance (Tlim) to a greater extent when cycling at high compared with low pedal rates. In a randomized, placebo-controlled cross-over study, seven subjects (mean ± SD, age 21 ± 2 yr, body mass 86 ± 10 kg) completed severe-intensity step cycle tests at pedal cadences of 35 rpm and 115 rpm during separate nine-day supplementation periods with NO3−-rich beetroot juice (BR) (providing 8.4 mmol NO3−/day) and placebo (PLA). Compared with PLA, plasma nitrite concentration increased 178% with BR ( P < 0.01). There were no significant differences in muscle oxyhemoglobin concentration ([O2Hb]), phase II V̇o2kinetics, or Tlim between BR and PLA when cycling at 35 rpm ( P > 0.05). However, when cycling at 115 rpm, muscle [O2Hb] was higher at baseline and throughout exercise, phase II V̇o2kinetics was faster (47 ± 16 s vs. 61 ± 25 s; P < 0.05), and Tlim was greater (362 ± 137 s vs. 297 ± 79 s; P < 0.05) with BR compared with PLA. These results suggest that short-term BR supplementation can increase muscle oxygenation, expedite the adjustment of oxidative metabolism, and enhance exercise tolerance when cycling at a high, but not a low, pedal cadence in healthy recreationally active subjects. These findings support recent observations that NO3−supplementation may be particularly effective at improving physiological and functional responses in type II muscle fibers.

Arbuscular mycorrhizal fungi (AMF) appear to be highly associated with arsenic (As) uptake in host plants because arsenate (As(V)) and phosphorus (P) share the same transporter, whereby AMF can enhance P uptake. A short-term experiment was conducted for low- (0 to 0.05 mM As) and high-affinity (0 to 2.5 mM As) uptake systems, to investigate the AMF role on As uptake mechanism in plants, which may explain As uptake kinetics in upland rice cultivar: Zhonghan 221. When concentration of As ranged from 0 to 0.05 mM, Funneliformis geosporum (Fg) significantly decreased arsenite (As(III)) and monomethylarsonicacid (MMA) uptake when (p0.05) compared to non-mycorrhizal (NM) treatment, since the major route for (As(III)) in rice roots-rice silicon transporter Lsi1 would be influenced by Fg inoculation at high As concentrations. Fg can also reduce As(V) uptake significantly (p0.05) under both uptake systems relative to NM treatment, whereas, Funneliformis mosseae (Fm) increased As(V) and MMA uptake in rice roots, with MMA uptake rate generally lower than As(III) and As(V). Using suitable AMF species inoculation with rice, As uptake and accumulation in rice grains can be reduced and the risk to human health, once consumed, can be minimized.

We assessed the effect of mycorrhizal inoculation on short-term uptake kinetics of arsenate and arsenite by excised roots of upland rice (Oryza sativa L. cv. Zhonghan 221). A concentration of 0.01–0.05 mM arsenic (As) differentially affected the influx rates of both arsenate and arsenite into rice roots non-inoculated or inoculated with Glomus mosseae and G. versiforme. While Vmax for arsenate uptake by non-mycorrhizal roots was 1.02 µmol g−1 fresh weight h−1, it was reduced by a factor of 2.4 for mycorrhizal roots (about 0.42 µmol g−1 fresh weight h−1) in the high-affinity uptake system. However, at high concentrations of 0.5–2.5 mM As only G. versiforme was able to reduce As influx. The results show that mycorrhizal effects on As uptake of upland rice are both concentration and species-specific.

Arsenic (As) and cadmium (Cd) are noxious and carcinogenic pollutants that can be removed from water by using emerging, ecofriendly, phytofiltration technology that employs Micranthemum umbrosum. After culturing M. umbrosum for 7 days in a hydroponic experiment, accumulation of 1219±44.11 µg As g−1 and 799.40±30.95 µg Cd g−1 were observed in the leaves, from 1000 µg As L−1 and 1000 µg Cd L−1 of water, respectively. Plant and water samples were analyzed for assessing the As and Cd accumulations, translocations, phytotoxic effects, uptake mechanisms and kinetics, and for evaluating the potential of M. umbrosum in As and Cd phytofiltration. The uptake pattern was leaf>stem>root for both pollutants. The plant showed higher resistance to As than to that to Cd. Uptake of inorganic As species was much greater than that of organic As and was found at above the substrate concentration. However, Cd showed similar uptake pattern to that of inorganic As species, and the data was better fit to a non-linear than a linear model. Low molecular weight substances that have thiol group(s) may be responsible for the binding of As in plants whereas Cd showed a different mechanism to that of As. M. umbrosum showed good As phytofiltration capabilities without any phytotoxic effects, but it was found to be a moderate accumulator of Cd with some phytotoxic effect compare to some other previously studied plant.

To date little is known about the reliability of peak oxygen consumption ( V ˙ O 2PEAK ) in incremental metronome paced step tests (IST) and the reliability of on-kinetics V ˙ O 2 has never been studied. We aimed to study the reliability of both tests. Eleven healthy subjects performed two ISTs until exhaustion. On two different days two duplicate 4 min constant metronome paced step tests (CST) were performed. V ˙ O 2PEAK , mean response time (MRT) and phase II time constant (τ) were tested for reproducibility using the paired t-tests, in addition to the limits of agreement (LOA) and within subject coefficient of variation (COV). With a 95% LOA of 0.38 to 0.26 L min−1, −8.7 to 9.1 s and −9.9 to 10.5 s they exhibit a COV of 3%, 4.5% and 6.9% for V ˙ O 2PEAK , MRT and τ respectively. ST are sufficiently reliable for maximal and submaximal aerobic power assessments in healthy subjects and new studies of oxygen uptake kinetics in selected patient groups are warranted.

The main objective of this study was to evaluate the performance of a model for simulating the uptake of various pesticides on passive air samplers (PAS). From 2006-2007 a series of PAS using XAD-resin were deployed at Egbert, a rural agricultural site in southern Ontario, Canada, to measure the uptake of pesticides for time periods ranging from two months to one year. A continuous increase in sequestered amounts was observed for most pesticides, except for trifluralin and pendimethalin, which could conceivably be subject to substantial degradation inside the sampler. Continuous low-volume active air samples taken during the same period, along with data on weather conditions, allowed for the simulation of the uptake of the pesticides using the model (PAS-SIM). The modelled accumulation of pesticides on the PAS over the deployment period was in good agreement with the experimental data in most cases (i.e., within a factor of two) providing insight into the uptake kinetics of this type of sampler in the field. Passive sampling rates (PSR, m(3) d(-1)) were determined from the empirical data generated for this study using three different methods and compared with the PSRs generated by the model. Overall, the PAS-SIM model, which is capable of accounting for the influence of temperature and wind variations on PSRs, provided reasonable results that range between the three empirical approaches employed and well-established literature values. Further evaluation and application of the PAS-SIM model to explore the potential spatial and temporal variability in PAS uptake kinetics is warranted, particularly for established monitoring sites where detailed meteorological data are more likely to be available.

Made available in DSpace on 2015-11-03T15:29:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-12-17 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Information regarding the characteristics that affect P-uptake capacity may assist in the selection of more adapted potato (Solanum tuberosum L.) cultivars and more adequate fertilization management for each cultivar. This study evaluated the P-uptake capacity of potato cultivars (Agata, Asterix, Atlantic, Markies, and Mondial) grown under P-deficient (2 mg L-1) or P-sufficient (31 mg L-1) conditions in nutrient solution and related it to physiological parameters of uptake and morphological root characteristics. When the plants were 24 days old, they were subjected to a P-uptake kinetics study. The length and surface area of roots and the uptake kinetic parameters (I-max, K-m, and C-min) varied among potato cultivars. Phosphorus-deficient potato plants had an approximately 60% smaller root surface area and an increase of 86% in the I-max and net P influx compared with the plants in P-sufficient conditions. However, these modifications in P uptake kinetics can do not influence P acquisition in the soil environment due to very limited P diffusion. The amount of P accumulated by plants grown under P-deficient conditions was directly related to the root length and surface area; a greater root surface, as demonstrated by the Asterix cultivar, is the most important factor for achieving a greater P-uptake capacity. Under P-sufficient conditions, potato cultivars such as Markies and Mondial showed a balance between morphological root characteristics (medium/large length and surface area) and physiological parameters (medium/high I-max values and net P influx) and had a greater P-uptake capacity. However, under field conditions, the responses to P deficiency may be different due to the very limited diffusion of P in the soil and because plants can use additional mechanisms to improve their P uptake from the soil. (C) 2014 Elsevier B.V. All rights reserved. Sao Paulo State Univ UNESP, Ctr Res Trop Tubers &Starches CERAT, BR-18610307 Sao Paulo, Brazil Sao Paulo State Univ UNESP, Coll Agr Sci, Dept Crop Sci, BR-18610307 Sao Paulo, Brazil Sao Paulo State Univ UNESP, Ctr Res Trop Tubers &Starches CERAT, BR-18610307 Sao Paulo, Brazil Sao Paulo State Univ UNESP, Coll Agr Sci, Dept Crop Sci, BR-18610307 Sao Paulo, Brazil FAPESP: 2010/04987-6 FAPESP: 2010/18600-6