Search

Ionic liquids are playing an increasingly relevant role in green chemistry due to one of their main important characteristic, their negligible vapour pressure, which means they are non-contaminant (o harmless) to the atmosphere. Nevertheless, they could be toxic for terrestrial ecosystems and therefore research to assess its toxicity to aquatic and terrestrial environments should be performed to assess whether they are as innocuous as sometimes assumed. The 1,3 dimethylimidazolium dimethylphospate, [C1C1Im][DMP], is an imidazolium ionic liquid with potential use in several industrial applications. Thus estimating the toxicity of this compound to these terrestrial ecosystems is of priority. In this study, we investigated the impact of different amounts of 1,3-dimethylimidazolium dimethyl phosphate ([C1C1Im][DMP]) on soil microbial activity by using two different methods: isothermal microcalorimetry and the classical method for measuring basal soil respiration. The aims of the study were to estimate the toxicity of this compound to soil microorganisms, to assess whether both methods were equally sensitive to estimate the impact of this ionic liquid on soil microbial activity and to combine the information obtained by both methods to obtain a more insightful picture of the impact of this compound on soil microbial activity. [ABSTRACT FROM AUTHOR]

Isothermal microcalorimetry is used to study the heat flow of lithium-ion cells to provide insight into active material characteristics and to provide data required for a thermal optimization on the cell and system level. Recent research has shown the application of this technique to cells during high cycling rates, for example fast charging. However, the limitation of isothermal microcalorimetry is the low-pass characteristic of the measured heat flow, introduced by the thermal inertia of the setup and the calorimeter itself. To solve this problem, we introduce an optimized cell holder design and a novel data processing method for a time-resolved measurement of highly dynamic heat flow profiles. These are described in detail and validated using a synthetic power profile applied to a dummy cell. Experiments on a graphite-lithium half-cell illustrate the improvement of the method and the optimized cell holder when compared to the state-of-the-art setup, demonstrating the 3.6 times faster time response, which was further improved using a post-processing deconvolution technique. The thus improved time resolution provides the acquisition of more detailed features than currently shown in the literature and allows an accurate correlation of the thermal signals to electrochemical features like, e.g., the differential voltage of the cell. [ABSTRACT FROM AUTHOR]

Part II of this 2-part series examines the impact of competitive graphite materials on NMC811 pouch cell performance using Ultra-High Precision Coulometry (UHPC), isothermal microcalorimetry, and in-situ stack growth. A simple lifetime projection of the best NMC811/graphite cells as a function of operating temperature is made. We show that graphite choice greatly impacts fractional fade, while fractional charge endpoint capacity slippage was largely unchanged due to identical cathodes. We show that an increase in graphite 1st cycle efficiency due to limited redox-active sites--favourable for minimizing Li inventory loss--is concomitant with an increase in negative electrode charge transfer resistance. Further, we demonstrate that cells with competitive artificial graphites (AG) have a lower parasitic heat flow (~0.060 mW A-1 h-1 at 40°C) compared to cells with natural graphites (NG), and that the cells with the AGs had minimal stack thickness change with cycling. Finally, we model SEI growth for NMC811 cells limited to 4.06 V with the square-root time model, and project that the best NMC811/graphite cells here can have decadeslong lifetimes at 20 -30 °C when Li plating is avoided. Such cells are excellent candidates for grid storage applications where energy density is less important compared to long lifetime. [ABSTRACT FROM AUTHOR]

Magnetic microcalorimeter (MMC) gamma-ray detectors are operated at temperatures below 0.05 K to provide an order of magnitude higher energy resolution than conventional high-purity germanium (HPGe) detectors. This comes at the cost of a small pixel size, which limits the practical energy range of MMCs to ~200 keV, and slow speed, which limits the statistical accuracy of a single-pixel spectrum. Still, MMCs may be able to improve the accuracy of nondestructive assay (NDA) of mixed-isotope U and Pu samples whose signature emissions in the 100 keV region are affected by line overlap and by a high Compton background. We are developing MMC gamma-ray detector arrays based on Au absorbers and paramagnetic Ag:Er sensors for NDA of U and Pu samples in nuclear safeguards. They have achieved an energy resolution below 40 eV FWHM at 60 keV and exhibit a linear response with a small and constant quadratic non-linearity. This paper characterizes MMC performance with the isotope 169Yb that is particularly interesting because it has four strong and very accurately known gamma emissions in the 100 keV region that is used for accurate NDA of U and Pu. We show that 169Yb can be used to calibrate the relative detection efficiency of MMCs with an average accuracy of 0.46% in the region from 85--135 keV. This can reduce the contribution of the efficiency correction to the uncertainty of U and Pu NDA to <0.1 %. The measurements also show that the weak putative 169Yb gamma rays at 63.01 and 129.94 keV most likely do not exist, and if they do, that their branching ratio is sufficiently low to not affect the accuracy of detector calibrations. As an example, we use the strong gold escape lines to measure an Au Ka2/Ka1 ratio of 0.590(4) whose precision exceeds the literature value by a factor of ~5. [ABSTRACT FROM AUTHOR]

Advances in both instrumentation and data analysis software are now enabling the first ultra-high-resolution microcalorimeter gamma spectrometers designed for implementation in nuclear facilities and analytical laboratories. With approximately ten times better energy resolution than high-purity germanium detectors, these instruments can overcome important uncertainty limits. Microcalorimeter gamma spectroscopy is intended to provide nondestructive isotopic analysis capabilities with sufficient precision and accuracy to reduce the need for sampling, chemical separations, and mass spectrometry to meet safeguards and security goals. Key milestones were the development of the SOFIA instrument (Spectrometer Optimized for Facility Integrated Applications) and the SAPPY software (Spectral Analysis Program in PYthon). SOFIA is a compact instrument that combines advances in large multiplexed transition-edge sensor arrays with optimized cryogenic performance to overcome many practical limitations of previous systems. With a 256-pixel multiplexed detector array capable of 5,000 counts per second, measurement time can be comparable to high-purity germanium detectors. SAPPY was developed to determine isotopic ratios in data from SOFIA and other microcalorimeter instruments with an approach similar to the widely-used FRAM software. SAPPY provides a flexible framework with rigorous uncertainty analysis for both microcalorimeter and high purity germanium (HPGe) data, allowing direct comparison. We present current results from the SOFIA instrument, preliminary isotopic analysis using SAPPY, and describe how the technology is being used to explore uncertainty limits of nondestructive isotopic characterization, inform safeguards models, and extract improved nuclear data including gamma-ray branching ratios. [ABSTRACT FROM AUTHOR]

Anode-free Li metal cells are one of the most appealing energy storage technologies beyond Li-ion batteries due to their superior theoretical specific and volumetric energy densities. However, long cycle life in an anode-free cell remains elusive due to difficulties reversibly plating and stripping metallic lithium. Isothermal microcalorimetry was used to study parasitic reactions in anode-free Li metal cells for electrolytes containing different Li salts. A new cycling protocol was used to measure the parasitic heat flow both on freshly plated Li surfaces and anode surfaces after stripping lithium. Existing methods were used to measure parasitic reactions occurring at high voltage. In both low- and high-voltage measurements, electrolytes containing LiDFOB had the highest parasitic heat flow compared to an electrolyte with LiPF6 salt. In contrast to previous studies of parasitic reactions in Li-ion batteries using isothermal microcalorimetry, the LiDFOB-containing electrolytes gave the longest lifetime despite having higher parasitic heat flow. This observation was attributed to decomposition of the LiDFOB salt, and subsequent formation of a favorable SEI layer that greatly improves plating and stripping efficiency. In-situ detection of parasitic heat flow with isothermal microcalorimetry techniques will be valuable for future studies of electrolyte design in anode-free Li metal cells. [ABSTRACT FROM AUTHOR]

Advanced integration efforts for safeguards were applied to assist the development of the Virtual Facility Distributed Test Bed (VFDTB). The sensor modeling work in this paper assisted both the safeguards and security modeling work for a pyroprocessing facility as part of the VFDTB. Sensor data and statistical analysis was integrated into a three-dimensional facility model and the Separation and Safeguards Performance Model (SSPM). To assist the development of the three-dimensional facility model, a pyroprocessing process hot cell was modeled in Monte Carlo N-Particle Code (MCNP) to map both its gamma and neutron radiation field with time. This model was comprised of simplified models of pyroprocessing equipment and utilized radiation source terms calculated from mass movement data from the SSPM. This work also helped inform the SSPM through MCNP modeling of the high dose neutron detector (HDND) and a microcalorimeter detector both developed at Los Alamos National Laboratory (LANL). The modeling examined the measurement and detection of the diversion of special nuclear material (SNM) in a pyroprocessing uranium product ingot. In addition to ingot counting, the HDND model was simulated in the hot cell model to determine potential radiation signatures that could be monitored to generate conclusions about the movement of material with time and to calculate background radiation in the hot cell. The results of the hot cell mapping and the assessment of the ingot for both neutron and gammas are presented in this paper. [ABSTRACT FROM AUTHOR]

As part of the U. S. Department of Energy Office of Nuclear Energy MPACT campaign Virtual Facility Distributed Test Bed, Los Alamos National Laboratory has developed advanced nondestructive assay (NDA) technologies based on gamma ray and neutron signatures. This paper focuses on the development of ultra-high resolution microcalorimeter gamma spectroscopy and the High Dose Neutron Detector (HDND) and their performance evaluation in relation to key measurement points within the Virtual Facility Distributed Test Bed flowsheet. Gamma ray spectroscopy and correlated neutron counting are cornerstones of nuclear material assay for safeguards and security. Advanced nuclear fuel cycles that utilize technologies such as electrochemical separation of spent nuclear fuel (SNF) present new measurement challenges and call for the development of new solutions. The development of microcalorimeter gamma spectroscopy is intended to provide nondestructive isotopic analysis capabilities with sufficient precision and accuracy to reduce the need for sampling and destructive analysis (DA) to meet safeguards and security goals. With nearly 10 times better energy resolution than high-purity germanium detectors, ultra-high-resolution microcalorimeter gamma ray spectrometers have been shown to overcome important uncertainty limits for nondestructive isotopic analysis. Recent development has led to the first microcalorimeter spectrometers designed for use in nuclear facilities and analytical laboratories, including SOFIA (Spectrometer Optimized for Facility Integrated Applications). Implemented in an on-site analytical laboratory, SOFIA could enable precise measurement of the isotopic composition of process samples in a much more rapid and cost-effective manner than destructive analysis. Daily nondestructive measurements to determine changes in key isotopic ratios with 1% 1-sigma precision for input fuel, ER salt, and U/TRU product are feasible with the current instrument. Relative to planar HPGe detectors, SOFIA can significantly improve confidence in results and reduce potential measurement bias by resolving closely spaced gamma ray peaks. The development of the HDND enables the capability to perform neutron counting and NDA in high gamma backgrounds and high count rate applications such as measurements of U/TRU products. The HDND is shown to be capable of tolerating increases in gamma dose rate by almost two orders of magnitude (up to 800 R/hr) with only ~30% reduction in neutron detection efficiency. To demonstrate the HDND performance for U/TRU product accountancy, the instrument was tested with high-mass Pu-bearing U/TRU surrogate materials and demonstrated the capability to measure multiplication using correlated neutron counting. Additionally, the HDND provides a dual capability of neutron and gamma detection for simultaneous neutron counting and gamma-dose measurements and is shown to be a versatile tool for process monitoring applications. By leveraging these and other advanced measurement technologies for electrochemical facilities, development of a robust and economic safeguards approach will be an important enabling capability for the next generation of nuclear energy. [ABSTRACT FROM AUTHOR]

Ni-rich positive electrode materials for Li-ion batteries have the dual benefit of achieving high energy density while reducing the amount of Co used in cells. However, limitations in cycle life are still an issue for the widespread adoption of these materials. The benefit of using single crystal materials has been demonstrated for LiNi0.5Mn0.3Co0.2O2 (NMC532), LiNi0.6Mn0.2Co0.2O2 (NMC622), and now LiNi0.8Mn0.1Co0.1O2 (NMC811). This work uses long-term cycling, ultra-high precision coulometry (UHPC), and isothermal microcalorimetry to investigate the effect of particle morphology on the lifetime of NMC811/graphite pouch cells. NMC811 with uncoated single crystal (SC) particles, coated polycrystalline (PC) particles, and a composite “bimodal” (BM) material are studied with electrolyte systems that have shown excellent cycle life in other NMC materials. Results from this work show that SC cells have improved cycle life in long-term cycling, as well as higher coulombic efficiency (CE) and lower charge endpoint capacity slippage as seen in the UHPC measurements. This correlates well with the isothermal microcalorimetry results, in which SC cells show the lowest parasitic heat flow over a range of uppercutoff voltages. This study suggests excellent lifetimes can be achieved in single crystal NMC811/graphite cells with further electrolyte optimization. [ABSTRACT FROM AUTHOR]

In non-ferrous metal tailings, combined pollution in the surrounding soil is caused by heavy metals and flotation chemicals. The combined effects of nickel (Ni) and its primary ore processing collector, sodium butyl xanthate (SBX), on soil microbial activity were investigated following the fluorescein diacetate hydrolase (FDA) and sucrase (SA) activities, and isothermal microcalorimetry during 60 days. FDA and SA activities as well as overall soil microbial activity were significantly affected by Ni, SBX and Ni/SBX mixture. The inhibition rate ( I ) of the growth rate constant ( k ) being higher with the Ni/SBX mixture than with SBX alone during the experiment. The growth rate constant ( k ) was positively correlated ( p  < 0.05 or p  < 0.01) with enzyme activities (FDA and SA) indicating that k represented a valuable proxy to evaluate the toxic effect of metals and flotation reagents on soil microorganisms. Thus, microcalorimetry was a useful method to characterize soil microbial communities. [ABSTRACT FROM AUTHOR]

Highlights • CO 2 adsorption studies at two different temperatures (40 °C and 60 °C) revealed that capture capacities increased with rise in temperature thereby confirming that it is an activated process. • Recyclability studies for CO 2 adsorption revealed that the sorbents possessed good stability, activity, and repeatability for a cycle of 3–5 consecutive runs. • Simultaneous determination of adsorption capacities and corresponding associated heats provided critical real-time insights into the adsorption process and can be used as an effective tool for screening potential sorbents. Abstract CO 2 adsorption was studied on different amines immobilized on silica, polymethyl methacrylate (PMMA) and mesoporous SBA-15 substrates. Hyperbranched polyethyleneimine (PEI) was impregnated onto silica and PMMA to generate Type I sorbents and their CO 2 adsorption capacities were measured and compared to the respective unmodified supports. Amine-functionalized Type II sorbents were also synthesized by loading different amounts of a monoamine ((3-Aminopropyl) triethoxysilane), a diamine (N -[3-(Trimethoxysilyl) propyl] ethylenediamine) and a triamine (N 1-(3-Trimethoxysilylpropyl) diethylenetriamine) onto mesoporous SBA-15 using grafting techniques. Nitrogen physisorption studies, surface density measurements and low angle XRD plots indicated a progressive filling of SBA-15 pores with increase in respective amine loadings. CO 2 breakthrough studies conducted on PEI impregnated silica and PMMA at 40 °C and 60 °C showed that the temperature strongly influenced the CO 2 adsorption capacities. The amount of total CO 2 captured on amine-grafted SBA-15 sorbents increased with rise in amine density and amine type in the order Triamine > Diamine > Monoamine. All recyclability studies on the amine-modified sorbents yielded consistent CO 2 capture capacities over a period of 3–5 adsorption–regeneration cycles. Simultaneous determination of adsorption capacities and corresponding associated heats at important stages of a complete CO 2 breakthrough run (under both dry & moist conditions) provided critical real-time insights into the adsorption process and can be used as an effective tool for screening potential sorbents. [ABSTRACT FROM AUTHOR]

Typical measurements of parasitic heat flow in lithium-ion cells can determine the magnitude of heat flow but cannot differentiate between different types of reactions. This causes difficulty when comparing cells that contain different coatings and solvent systems, which may affect parasitic reaction pathways. In this work, a new technique to measure the rate and net enthalpy change (ΔH) of parasitic reactions in lithium ion cells is introduced. Isothermal microcalorimetry and precision current measurements are used to make in-situ, non-destructive measurements of heat flow and parasitic current during high-voltage holds. The results are used to determine ΔH of parasitic processes in NMC532/graphite pouch cells. Effects of positive electrode coating, solvent, and upper cutoff voltage are explored. Solvent systems of organic carbonates with and without methyl acetate, and fluorinated carbonates are also investigated. Each solvent system yielded a unique trend of ΔH with increased voltage, and results were consistent between pair cells. Cells with organic carbonates showed consistent ΔH between voltages, while cells containing methyl acetate showed decreasing ΔH. Cells containing fluorinated carbonates showed increasing ΔH with increased voltage. The observed trends in ΔH and solvent systems as well as future developments of this method are discussed. [ABSTRACT FROM AUTHOR]

Trypanosoma congolense is a protozoan parasite that is transmitted by tsetse flies, causing African Animal Trypanosomiasis, also known as Nagana, in sub-Saharan Africa. Nagana is a fatal disease of livestock that causes severe economic losses. Two drugs are available, diminazene and isometamidium, yet successful treatment is jeopardized by drug resistant T. congolense . Isothermal microcalorimetry is a highly sensitive tool that can be used to study growth of the extracellular T. congolense parasites or to study parasite growth inhibition after the addition of antitrypanosomal drugs. Time of drug action and time to kill can be quantified in a simple way by real time heat flow measurements. We established a robust protocol for the microcalorimetric studies of T. congolense and developed mathematical computations in R to calculate different parameters related to growth and the kinetics of drug action. We demonstrate the feasibility and benefit of the method exemplary with the two standard drugs, diminazene aceturate and isometamidium chloride. The method and the mathematical approach can be translated to study other pathogenic or non-pathogenic cells if they are metabolically active and grow under axenic conditions. [ABSTRACT FROM AUTHOR]

Isothermal microcalorimetry is used to investigate the effect of different Li(Ni1-x-yMnxCoy)O2 materials (NMC442, NMC532, NMC622) and coatings (Al2O3 and a proprietary high voltage coating) on parasitic reactions that occur in Li-ion pouch type cells. NMC/graphite pouch cells were prepared with a typical organic carbonate-based electrolyte containing a well-known additive blend and were tested up to 4.4 V at 40°C. A new method of extracting the parasitic heat flow during both charge and discharge is introduced. Differences between charge and discharge parasitic heat flow yielded more insight into the behavior of high voltage parasitic reactions. Ultra-high precision coulometry, long-term charge discharge cycling, in-situ gas measurements, and electrochemical impedance spectroscopy were also used to compare the observed heat flow to well-known performance metrics. All coated cell types performed significantly better than uncoated NMC442/graphite cells. It was found that the magnitude of the parasitic heat flows did not correlate as expected to the precision coulometry results nor to the long term cycling results. In particular, cells with Al2O3-coated NMC622 had the highest parasitic heat flow among the cells with coated electrodes but competed for best performance in the cycling tests. The possible reasons for this unexpected result are explored. [ABSTRACT FROM AUTHOR]

Degradation of PAEs influenced by humic substance (HS) is a fundamental biological/chemical process happened in soil. It was commonly believed that the sequestration of PAEs by HS is the dominant mechanism. However, by far, detail relationships between bioavailability of HS-PAEs complex and degradation behavior of PAEs still remains unclear. For this, the effect of HA and FA on degradation of PAEs were investigated by batch experiment in our work. The interactions between HA/FA and DBP were examined using fluorescence spectroscopy. Microcalorimetry combined with QSAR model analysis were applied to assess bioavailability of HS-PAEs complex and further interpret the effect of HS on degradation of PAEs. The results indicated that the complex formed between DBP and HA inhibit the metabolic activity in soil while opposite effect was found for FA-PAEs complex, which were sensitively reflected by the heat power. In addition, traditional 2D-QSAR model coupled with 3D contour maps highlight the mutual effects of quantum chemical parameters and HS on degradation of PAEs in soil, and further proved that bioavailability of HA/FA-PAEs complex were responsible for controlling the degradation rate in soil. This study provides interesting new insights in the effect of HS on degradation of PAEs in soil. • Contradictory effect of HS on biodegradation of DBP was found between HA and FA. • Microcalorimetric could sensitively evaluate the bioavailability of HS-PAEs complex. • QSAR models provide theoretical and visualized support for revealing mechanism. • Bioavailability of HS-PAEs complex are responsible for controlling biodegradation. [ABSTRACT FROM AUTHOR]

Fluorinated carbonates such as fluoroethylene carbonate (FEC) and di-2,2,2-trifluoroethyl carbonate (TFEC) improve cycling performance and decrease parasitic reactions at high potentials. However they also decrease cell life at lower voltage ranges compared to typical organic carbonate solvents. A method of quantifying the parasitic heat flow during open circuit and voltage hold conditions was implemented using isothermal microcalorimetry on Li-ion pouch cells to investigate the effect of additives in FEC:TFEC (3:7) and the effects of blending ethylene carbonate (EC):ethylmethyl carbonate (EMC) 3:7 with FEC:TFEC (3:7) in order to reduce parasitic reactions during operation at 4.2 V, 4.4 V and 4.6 V. Additives were found to lower parasitic heat flow in FEC:TFEC at all operating potentials, however to less of an effect at 4.6 V. Blending EC:EMC and FEC:TFEC resulted in decreased rates of parasitic reactions at all operating potentials compared to EC:EMC alone. Cells with unblended FEC:TFEC exhibited the lowest parasitic heat flow at 4.4 V and 4.6 V, although they produced more gas than EC:EMC containing blends. This work demonstrates the advantage of blending fluorinated carbonates with traditional solvents, particularly during use at low operating potentials, as well as demonstrating some advantages of fluorinated carbonates for high voltage lithium ion battery applications. [ABSTRACT FROM AUTHOR]

Hydrocarbon pollution is a worldwide problem. In this study, five surfactants containing SDS, LAS, Brij 30, Tween 80 and biosurfactant were used to evaluate their effect on crude oil biodegradation. Hydrocarbon degrading bacteria were isolated from oil production water. The biosurfactant used was a kind of cyclic lipopeptide produced by Bacillus subtilis strain WU-3. Solubilization test showed all the surfactants could apparently increase the water solubility of crude oil. The microbial adhesion to the hydrocarbon (MATH) test showed surfactants could change cell surface hydrophobicity (CSH) of microbiota, depending on their species and concentrations. Microcalorimetric experiments revealed these surfactants exhibited toxicity to microorganisms at high concentrations (above 1 CMC), except for SDS which showed low antibacterial activity. Surfactant supplementation (about 0.1 and 0.2 CMC) could improve degradation rate of crude oil slightly, while high surfactant concentration (above 1 CMC) may decrease the degradation rate from 50.5% to 28.9%. Those findings of this work could provide guidance for the application of surfactants in bioremediation of oil pollution. [ABSTRACT FROM AUTHOR]

LiNi0.8Mn0.1Co0.1O2 (NMC811) can deliver a high capacity of ~200 mAh/g with an average discharge potential of ~3.8 V (vs. Li+/Li), making it a promising positive electrode material for high energy density lithium ion batteries. However, electrochemical tests from half cells and full cells show poor cycling performance when charged to potentials above 4.2 V. The calendar and cycle lifetimes of cells are affected by the structural stability of the active electrode materials as well as the parasitic reactions that occur in lithium ion batteries. In order to explore the major failure mechanisms of the material, half cells (coin cells) with control electrolyte and full cells (pouch cells) with control electrolyte and with selected electrolyte additives were tested over four different potential ranges. Isothermal microcalorimetry was used to explore the parasitic reactions and their potential dependence. ln-situ and ex-situ X-ray diffraction and scanning electron microscopy were used to investigate the structural and morphological degradation of the materials over cycling. It was found that the dramatic c-axis change of the active material during charge and discharge may not be the major problem for cells that are cycled to higher potentials. The parasitic reactions that arise from the interactions between the electrolyte and the highly reactive delithiated cathode surface at high potentials are suggested as the main reason for the failure of cells cycled above 4.2 V. It should be possible to further improve the performance of NMC811 at high potentials by modifying the cathode surface and/or identifying and using electrolyte blends which reduce parasitic reactions. [ABSTRACT FROM AUTHOR]

The toxicity of binary mixture of Cu2+ and phenols (phenol; o-nitrophenol; m-nitrophenol; p-nitrophenol) was evaluated using Tetrahymena thermophila as the model organism, by microcalorimetry, optical density, field emission scanning electron microscope (FESEM) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The growth curves and metabolic properties of Tetrahymena exposed to Cu2+ and phenols were monitored by microcalorimetry. Binary mixture toxicity changed with the concentration of Cu2+/phenols and the order of toxicity was Cu2+/phenol2+/m-nitrophenol2+/o-nitrophenol2+/p-nitrophenol. The results of FESEM and ATR-FTIR also indicated that Cu2+/phenols had a great effect on cell cortex and flagellum. A synergistic effect was noted between Cu2+ and phenols on Tetrahymena. [ABSTRACT FROM AUTHOR]

Fructose-1-phosphate (F1P) is the preferred effector of the catabolite repressor/activator (Cra) protein of the soil bacterium Pseudomonas putida but its ability to bind other metabolic intermediates in vivo is unclear. The Cra protein of this microorganism (Cra PP ) was submitted to mobility shift assays with target DNA sequences (the P fruB promoter) and candidate effectors fructose-1,6-bisphosphate (FBP), glucose 6-phosphate (G6P), and fructose-6-phosphate (F6P). 1 mM F1P was sufficient to release most of the Cra protein from its operators but more than 10 mM of FBP or G6P was required to free the same complex. However, isothermal titration microcalorimetry failed to expose any specific interaction between Cra PP and FBP or G6P. To solve this paradox, transcriptional activity of a P fruB -lacZ fusion was measured in wild-type and Δ fruB cells growing on substrates that change the intracellular concentrations of F1P and FBP. The data indicated that P fruB activity was stimulated by fructose but not by glucose or succinate. This suggested that Cra PP represses expression in vivo of the cognate fruBKA operon in a fashion dependent just on F1P, ruling out any other physiological effector. Molecular docking and dynamic simulations of the Cra-agonist interaction indicated that both metabolites can bind the repressor, but the breach in the relative affinity of Cra PP for F1P vs FBP is three orders of magnitude larger than the equivalent distance in the Escherichia coli protein. This assigns the Cra protein of P. putida the sole role of transducing the presence of fructose in the medium into a variety of direct and indirect physiological responses. [ABSTRACT FROM AUTHOR]

Abstract: The anti-bacterial activities of three types of di-O-caffeoylquinic acids (diCQAs) in Lonicera japonica flowers, a traditional Chinese medicine (TCM), on Bacillus shigae growth were investigated and compared by microcalorimetry. The three types of diCQAs were 3, 4-di-O-caffeoylquinic acid (3, 4-diCQA), 3, 5-di-O-caffeoylquinic acid (3, 5-diCQA), and 4, 5-di-O-caffeoylquinic acid (4, 5-diCQA). Some qualitative and quantitative information of the effects of the three diCQAs on metabolic power-time curves, growth rate constant k, maximum heat-output power Pm , and the generation time tG , total heat output Qt , and growth inhibitory ratio I of B. shigae were calculated. In accordance with a thermo-kinetic model, the corresponding quantitative relationships of k, Pm, Qt, I and c were established. Also, the half-inhibitory concentrations of the drugs (IC50) were obtained by quantitative analysis. Based on the quantity-activity relationships and the IC50 values, the sequence of inhibitory activity was 3, 5-diCQA > 4, 5-diCQA > 3, 4-diCQA. The results illustrate the possibility that the caffeoyl ester group at C-5 is the principal group that has a higher affinity for the bacterial cell, and that the intramolecular distance of the two caffeoyl ester groups also has an important influence on the anti-bacterial activities of the diCQAs. [Copyright &y& Elsevier]

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are widespread in various ecosystems and are pollutants of great concern due to their potential toxicity, mutagenecity and carcinogenicity. Surfactant has become a hot topic for its wide application in the bioremediation of PAHs. The aim of this work is to explore a microcalorimetric method to determine the toxic effect of pyrene on Bacillus subtilis (B. subtilis) and the PAH-degrading bacteria Burkholderia cepacia (B. cepacia) and to evaluate the effect of Tween 80 on biodegradation of pyrene. Power–time curves were studied and calorimetric parameters including the growth rate constant (k), half inhibitory concentration (IC 50), and total thermal effect (Q T) were determined. B. subtilis, B. cepacia and B. cepacia with Tween 80 were completely inhibited when the concentration of pyrene were 200, 800 and 1600µgmL−1, respectively. B. cepacia shows better tolerance to pyrene than B. subtilis. Tween 80 significantly improves the biodegradation of pyrene by increasing the bioavailability of pyrene. In addition, the expression of catechol 2,3-dioxygenase (C23O) in B. cepacia is responsible for the degradation of pyrene and plays an important role in improving the biodegradation of pyrene. Moreover, the activity of C23O increases with the application of Tween 80. The enhanced bioavailability and biodegradation of pyrene by Tween 80 shows the potential use of Tween 80 in the PAHs bioremediation. [Copyright &y& Elsevier]

Fighting against water pollution requires the ability to evaluate the toxicity of pollutants such as herbicides. Tetrahymena pyriformis are ubiquitous ciliated protozoans commonly used in ecotoxicological research. Microcalorimetry can be used in many biological investigations as a universal, non-destructive and highly sensitive tool that provides a continuous real-time monitoring of the metabolic activity. This technique based on the thermal power output was applied to evaluate the influence of herbicide diuron on cultures of T. pyriformis. The heat flux produced upon addition of 0, 3.5, 7.0, 14.0, 28.0, and 56.0µgmL−1 of diuron was monitored. The biomass change during the growth was also determined by flow cytometry. The results confirmed that the growth of T. pyriformis is progressively inhibited as the concentration of diuron increases and revealed that the state of the living system is severely altered at a concentration of 56.0µgmL−1. The IC50 was estimated at 13.8µgmL−1 by microcalorimetry and at 18.6µgmL−1 by flow cytometry. It was shown that microcalorimetry is not only a very effective tool for the determination of the growth rate constant but that it is also a valuable probe for a rapid detection of the metabolic perturbations and, in ultimate cases, of the critical alterations of the living system under the action of a toxic agent. [Copyright &y& Elsevier]

Abstract: In this work, a new adsorbent material (ADS) was synthesized by immobilization of chitosan layers on fish scale fibrillar collagen in sequential reactions. Characterization of ADS has performed by FTIR, surface-enhanced Raman spectroscopy, TG/DTG and solid-state UV–vis reflectance spectroscopy. The characterization results have pointed that the chemically immobilized chitosan layers present stable adhesion on the collagenous matrix. The interaction of ADS with a dichlorophenol derivative (DCP) was studied by long-term solution microcalorimetry under isothermal conditions. The exothermic low value of the heat of swelling of ADS has related to the low value of the swelling entropy caused by the chemically immobilized chitosan layers on ADS. The energies of DCP sorption were from −2.41 to −4.31Jg−1 and the DCP sorption enthalpies were slightly exothermic. The maximum sorption capacity observed for DCP on ADS (45.7mmolg−1 or about 12,100mgg−1) is highly superior in relation to literature reports. The calorimetric results have suggested that diffusional transport is the main interaction mechanism at ADS/DCP interfaces. The present work underlines the excellent features of the new chitosan-based adsorbent for use in phenol sorption applications. [Copyright &y& Elsevier]

We performed a comparative study on the enzymological features of purified recombinant α-amylase of three species belonging to the Drosophila melanogaster species subgroup: D. melanogaster, D. erecta and D. sechellia. D. erecta and D. sechellia are specialist species, with host plant Pandanus candelabrum (Pandanaceae) and Morinda citrifolia (Rubiaceae), respectively. The temperature optima were around 57-60°C for the three species. The pH optima were 7.2 for D. melanogaster, 8.2 for D. erecta and 8.5 for D. sechellia. The kcat and Km were also estimated for each species with different substrates. The specialist species D. erecta and D. sechellia display a higher affinity for starch than D. melanogaster. α-Amylase activity is higher on starch than on glycogen in all species. α-Amylases of D. erecta and D. sechellia have a higher activity on maltooligosaccharides (G6 and G7) than on starch, contrary to D. melanogaster. Such differences in the enzymological features between the species might reflect adaptation to different ecological niches and feeding habits. [ABSTRACT FROM AUTHOR]

Abstract: The water adsorption properties of modified porous sorbents for solar thermal energy storage and heat transformation have been investigated by thermogravimetry (TG) differential thermogravimetry (DTG), microcalorimetry, measurements of water adsorption isotherms, and storage tests. A chabazite type SAPO, a dealuminated faujasite type zeolite, and a mesostructured aluminosilicate, have been synthesized and compared with common zeolites X, Y and silica gel. It has been found that optimized lattice composition and pore architecture contribute to well adapt hydrophilic properties and a beneficial steep isotherm. [Copyright &y& Elsevier]

Abstract: This paper describes a novel approach to the quality control of a Chinese herbal injection based on microcalorimetric determination of its effect on the biothermal active fingerprint (BTAF) of Escherichia coli (E. coli) growth. Yinzhihuang Injection (YZHI) was selected for this proof of concept study. Reference samples of YZHI were collected and compared with test (stressed) samples prepared under different stress conditions. The BTAF of E. coli growth was found to be affected by YZHI and the changes were analyzed on the basis of eleven biothermokinetic parameters. Similarity and multivariate statistical analysis were used to investigate the differences between reference and test samples and discriminant analysis was used to delineate the altered samples. Reference samples were found to have coincident BTAFs with similarity index >0.99. Stressed samples showed differences in the BTAF which increased in line with decreased quality. Discriminant formulae were developed based on a sensitivity parameter which could identify all altered samples. In conclusion, BTAF can be used to assess the quality of YZHI both qualitatively and quantitatively and has the potential to provide a sensitive method for quality control of Chinese herbal injections. [Copyright &y& Elsevier]

Abstract: We analyzed the initial adhesion and biofilm formation of Staphylococcus aureus (ATCC 29213) and S. epidermidis RP62A (ATCC 35984) on various bone grafts and bone graft substitutes under standardized in vitro conditions. In parallel, microcalorimetry was evaluated as a real-time microbiological assay in the investigation of biofilm formation and material science research. The materials β-tricalcium phosphate (β-TCP), processed human spongiosa (Tutoplast™) and poly(methyl methacrylate) (PMMA) were investigated and compared with polyethylene (PE). Bacterial counts (log10 cfu per sample) were highest on β-TCP (S. aureus 7.67±0.17; S. epidermidis 8.14±0.05) while bacterial density (log10 cfu per surface) was highest on PMMA (S. aureus 6.12±0.2, S. epidermidis 7.65±0.13). Detection time for S. aureus biofilms was shorter for the porous materials (β-TCP and processed human spongiosa, p <0.001) compared to the smooth materials (PMMA and PE), with no differences between β-TCP and processed human spongiosa (p >0.05) or PMMA and PE (p >0.05). In contrast, for S. epidermidis biofilms the detection time was different (p <0.001) between all materials except between processed human spongiosa and PE (p >0.05). The quantitative analysis by quantitative culture after washing and sonication of the material demonstrated the importance of monitoring factors like specific surface or porosity of the test materials. Isothermal microcalorimetry proved to be a suitable tool for an accurate, non-invasive and real-time microbiological assay, allowing the detection of bacterial biomass without removing the biofilm from the surface. [Copyright &y& Elsevier]

Abstract: It was found that the intestinal bacteria balance would be deteriorated by rhubarb especially in long term treatment. Bifidobacteria is one of the most common species of probiotics in human intestine. The suppression of this particular probiotic, such as Bifidobacterium adolescentis, one of the dominant anaerobes in the intestines of humans, might lead to imbalance of intestinal flora and is considered to be potentially riskful for human health. Hence, the inhibitory effects of the five main components of hydroxyanthraquinones (HAQs) contained in rhubarb on B. adolescentis growth were investigated by microcalorimetry to discover the suppression potential of rhubarb and the structure-function relationship of such HAQs. The value of the maximum power- output (Pmax) and slope (k) of the thermogenic growth curves of B. adolescentis were found of decrease in the presence of the five HAQs, while the peak time (Tp) of the thermogenic curves were found to be delayed. The sequence of antimicrobial activity of the five HAQs is rhein>emodin>aloe-emodin>chrysophanol>physicion. The functional groups carboxyl, hydroxyl and hydroxylmethyl on phenyl ring in HAQs could improve the antimicrobial activity. The influence of substituent groups on anti- B. adolescentis activity might be related with the polarity and the sequence was carboxyl>hydroxyl>hydroxylmethyl>methyl and methoxyl. [Copyright &y& Elsevier]

Abstract: A multi-channel thermal activity monitor was applied to study soil microbial activity in Wuhan brown sandy soil in the presence of different concentrations of hexavalent chromium . In order to stimulate the soil microbial activity, 5.0mg of glucose and 5.0mg of ammonium sulfate were added to a 1.20-g soil sample under a controlled humidity of 35%. The results show that the poisonous species of at an half inhibitory concentration value of against soil microbe, and an increase of the amount of hexavalent chromium is associated to a decrease in the microbial activity of the soil, probably due to an increase in the toxicity of hexavalent chromium, affecting strongly the life in this soil microbial environment. Our work also suggests that microcalorimetry is a fast, simple and more sensitive method that can be easily performed to study the toxicity of different species of heavy metals on microorganism compared to other biological methods. [Copyright &y& Elsevier]

Microorganisms are commonly bonded to various soil minerals, which may influence the redox processes and bacterial metabolism. However, little is known about the impact of particle size of soil minerals on these redox processes in the subsurface environment. In this study, the Cr(VI) bioreduction by Shewanella oneidensis MR-1 (S. oneidensis) was investigated in the presence of various hematite (α-Fe 2 O 3) particles with average diameters of 1.0 µm (hem-1 µm) and 80.0 nm (hem-80 nm) under different pH conditions. Fourier transformed infrared spectroscopy coupled with two-dimensional correlation spectroscopy (FTIR-2D-COS) analysis and isothermal titration calorimetry (ITC) were used to explore the interaction between S. oneidensis and hematite and monitor the bacterial metabolic activity, respectively. X-ray photoelectron spectroscopy (XPS) was used to elucidate the Cr(VI) removal mechanisms. Our results showed that 78% of chromate can be reduced to Cr(III) by S. oneidensis alone. Whereas, chromate reduction rates were 62% and 85% in the presence of hem-1 µm and hem-80 nm, respectively. The enhancement of Cr(VI) reduction by S. oneidensis -hem-80 nm complex may be due to the large surface area as well as the positive charge of hem-80 nm at neutral pH, which influences the physical contact between S. oneidensis and iron oxides. The microcalorimetric results showed that both hem-1 µm and hem-80 nm promoted the normal physiological functions of S. oneidensis. XPS confirmed the gradual FeCr 2 O 4 formation and Fe(II) depletion during the Cr(VI) reduction process. This work expands our understanding of microbial-mineral interaction and its role in Cr(VI) removal mechanisms in the subsurface environment. ga1 • Hem-80 nm accelerated Cr(VI) bio-reduction by S. oneidensis. • The Cr(VI) reduction rate was enhanced when the initial pH was higher than ZPC. • Hem-1 µm and hem-80 nm promote the normal physiological functions of S. oneidensis. • Biogenic produced Fe(II) may take part in the Cr(VI) reduction process. • XPS confirmed the FeCr 2 O 4 formation and Fe(II) depletion during the Cr(VI) removal. [ABSTRACT FROM AUTHOR]

Summary: Detection of mycobacterial infection can be achieved by different means; however, culture-based methods remain the gold standard. In this paper, we present a new culture-based method using real-time microcalorimetric detection of growth of Mycobacterium species including Mycobacterium tuberculosis. Microcalorimetric detection of heat production by 6 different growing species of Mycobacterium was achieved between 20 and 310h depending on their type (fast vs. slow-growing mycobacteria) and initial concentration. This study demonstrates that microcalorimetric detection of mycobacterial growth is a potential advantageous alternative to methods using fluorescent or radiolabeled growth indicators. [Copyright &y& Elsevier]

Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant which has been identified at significant levels in soils. Existed ecotoxicological studies have mainly employed earthworms to evaluate the toxicity of PFOA. However, little information do we know about the toxicity of PFOA regarding soil microorganisms. Accordingly, the adverse effects of PFOA on microbial activity in a wheat soil under four fertilization treatments were investigated in this study. The microcalorimetric results revealed that the toxicity of PFOA on soil microbial activity in four treatments followed a descending sequence: Control (no fertilization), NK (no P fertilizer, but N and K fertilizers were used), PK (no N fertilizer, but P and K fertilizers were used), and NPK (N, P and K fertilizers were used). The soil sample with higher available P content had higher resistant to PFOA. There were significant differences in urease activity and alkaline phosphatase activity among the four fertilization treated soils. Molecular modeling studies clearly demonstrated that the binding of PFOA with alkaline phosphatase was more stable than with urease through electrostatic interaction, van der Waals force, and hydrogen bonds. These results are expected to provide more comprehensive information in toxicity of PFOA in soil environment. Image 1 • The effect of PFOA on soil microbial activity followed: Control > NK > PK > NPK. • The higher the AP content, the higher the IC 50 value. • The urease and alkaline phosphatase activities decreased evidently. • The binding energy between PFOA and alkaline phosphatase was lower. The toxicity of PFOA on soil microbial activity in four treatments followed a descending sequence Control > NK > PK > NPK. [ABSTRACT FROM AUTHOR]