Miracle-dz/UniFAR-FTUs huggingface dataset:
The effect of reducing conditions on the solubility of phosphorus in a diverse range of European agricultural soils

The effects of reducing conditions on solubility of phosphorus (P) can directly influence water quality. The release of P is enhanced although the P is not directly involved in reduction processes. We here compare the responses to flooding of 12 overfertilized agricultural soils in widely varying pedological and management regimes, belonging to seven World Reference Base groups. The redox potential initially ranged from 305 to 515 mV and decreased to −157 to −195 mV within 32 days. The onset of reducing conditions led to an increase in the concentration of soluble P. The maximum rate of solubilization occurred within 1–3 weeks under reducing conditions, and the steady‐state concentrations of P never exceeded 200 μmol dm−3. Four stages in the development of the reduction process are identified, and a simple empirical model describes the change in concentrations of soluble P. The potential of P release under reduction is positively correlated with the soil saturation with P. Flooding over a few weeks triggered the release of large amounts of P. Constant pe + pH is related to constant concentration of molybdate‐reactive P, suggesting that soluble P is effectively buffered so that P will be immobilized. In general the solubilization of P under reducing conditions is likely to be aggravated by the increased soil P status that has resulted from overfertilization of agricultural land with P. These findings bear on the establishment and long‐term effectiveness of riparian buffer zones where phosphorus is likely to accumulate by the interception of drainage.
Complex lattice potentials in electron diffraction calculated for a number of crystals

Structure potentials, Vg, and absorption potentials for 100 keV-electrons are given in tabulated form for almost all monatomic crystals with elements Z = 3 to 90 and for a number of crystals of the rock-salt type. The absorption potentials are given in the form of the Fourier coefficients Ci0g of the Yoshioka imaginary potential for excitation of crystal electrons and excitation of phonons at the temperatures 20, 93 and 293 °K. All computations are based on numerical Hartree-Fock-Slater atomic radial functions by Herman & Skillman (Atomic Structure Calculations. Englewood Cliffs: Prentice Hall, 1963). The calculations show that the ratio Ci0g(el)/Vg, where Ci0g(el) refers to excitation of single-crystal electrons, lies between 0.005 and 0.012 for the lower reflexion vectors g and practically all Z. In contrast to this the ratio Ci0g(phonon)/Vg is much larger and increases about linearly with Z, for a given g.
Temperature-induced motion of interphase boundaries in confined ferroelectrics

Abstract Thermally induced dynamics of interphase boundaries are considered in confined ferroelectrics at a first-order phase transition. The size dependence of the temperature of the stability limit of the paraelectric phase and the phase transition temperature is calculated for a semi-infinite plate with one finite size (thickness). The velocity of the interphase boundary is presented as a function of its thickness for the thermally induced motion. The result is in agreement with the experiment on PbTiO3. It is shown that close to the phase transition the interphase boundary should change the direction of its motion at a critical thickness of the sample, reflecting the first-order character of the ferroelectric phase transition.
Electrical breakdown of carbon nanotube devices and the predictability of breakdown position

We have investigated electrical transport properties of long (>10 mu m) multiwalled carbon nanotubes (NTs) by dividing individuals into several segments of identical length. Each segment has different resistance because of the random distribution of defect density in an NT and is corroborated by Raman studies. Higher is the resistance, lower is the current required to break the segments indicating that breakdown occurs at the highly resistive segment/site and not necessarily at the middle. This is consistent with the one-dimensional thermal transport model. We have demonstrated the healing of defects by annealing at moderate temperatures or by current annealing. To strengthen our mechanism, we have carried out electrical breakdown of nitrogen doped NTs (NNTs) with diameter variation from one end to the other. It reveals that the electrical breakdown occurs selectively at the narrower diameter region. Overall, we believe that our results will help to predict the breakdown position of both semiconducting and metallic NTs. Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. http://dx.doi. org/10.1063/1.4720426]
Evaluation of antibacterial activity of silver nanoparticles synthesized by a novel strain of marine Pseudomonas sp.

Use of silver nanoparticles to manage pathogenic microorganisms is a modern trend in nanomedicine. Thus our study focused on utilizing the nanoparticle synthesizing properties of marine bacteria. Molecular identification of the selected bacterial strain was done by 16SrDNA sequencing based method, which showed it as a novel Pseudomonas strain. The biosynthesis of silver nanoparticles was obtained by treating the bacteria with 1mM AgNO3 and the isolate was found to have the ability to form silver nanoparticles intracellularly within 24 hours at room temperature. The silver nanoparticles synthesized by the novel isolate were characterized by UV-Vis spectroscopy and scanning electron microscope. The UV-Vis absorption analysis showed a peak at 430 nm corresponding to the surface plasmon resonance of silver nanoparticles. Also these silver nanoparticles were evaluated for their antibacterial efficacy against Salmonella typhi, Vibrio cholerae, Bacillus subtilis and Staphylococcus aureus.
Sulfate stimulation of mercury methylation in freshwater sediments

The relationship between bacterial sulfate reduction and mercury methylation, as well as the in situ distribution of methylmercury in sediments, was studied in Quabbin Reservoir, MA. Fish methylmercury levels in Quabbin and other lakes affected by acid deposition are often elevated. However, the cause of acceleration of net methylmercury production or bioaccumulation in these lakes is poorly understood. Experimental additions of sulfate to either anoxic sediment slurries or lake water above intact sediment cores resulted in increased microbial production of methylmercury from added inorganic mercury
Bourdons rares du Parc Naturel Régional du Queyras (Hautes-Alpes, France)

The author, who stayed in the Parc Naturel Régional du Queyras (France) between the 9 th and the 17 th August 2007, noted the presence of more than twenty species of bumblebees. This paper deals with the most interesting observations about Bombus gerstaeckeri M ORAWITZ , B. inexspectatus (T KALCU ), B. brodmannicus V OGT and the copulation of B. mendax G ERSTAECKER .
Molecular dynamics study of a polymer chain in solution

The behavior of a polymer chain in solution has been simulated by means of molecular dynamics techniques. The polymer itself is represented by a freely linked chain of hard spheres and the solvent by a hard sphere fluid. Both the equilibrium configurational properties of chains of various lengths and their time‐dependent autocorrelation functions are studied. The equilibrium behavior agrees with the results of previous work. The decay of the autocorrelation functions is exponential over a considerable range and the relaxation times, thus defined, appear to scale with the chain length. The effect of the solvent density is also examined.
Modeling and simulation of human induced pluripotent stem cell‐derived cardiac tissue

Human induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) have become a promising in vitro model for human native cardiomyocytes. Cultivated tissue samples beat autonomously and can be used for basic and pharmacological research. For mechanical measurements of these tissue samples, the CellDrum technology has been developed. Measurements are extended by simulations with a multi‐scale electromechanically coupled finite element method based model. This model can be parameterized and validated experimentally. The paper describes the model, its workflow, and preliminary simulations to study the effect of fibroblasts and a selected cardiac drug on the electromechanics of hiPSC‐CMs.
Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber

A sectional atmospheric chemistry and aerosol dynamics box model (AEROFOR) was further devel- oped and used to simulate ultra-fine particle formation and growth from seaweed in a chamber flushed with particle-free atmospheric air. In the model, thermodynamically stable clusters were formed by dimer nucleation of OIO vapour, whose precursor was assumed to be molecular I2 emitted by seaweed. Fractal geometry of particles was taken into account. For the I2 fluxes of (0.5-1.5) × 10 9 cm −3 s −1 the model predicted strong particle bursts, the steady state concentrations of I2 vapour and particles larger than 3 nm were as high as 4 × 10 9 −1.2 × 10 10 cm −3 and 5.0 × 10 6 -9.2 × 10 6 cm −3 respectively. The steady state was reached in less than 150 s and the predicted growth rates of 3-6 nm particles varied in the range of 1.2-3.6 nm min −1 . Sensitivity of the size distribution against I2O3 cluster formation, an extra condensable vapour, the photolysis rate of the OIO vapour as well as against the density of (OIO)n-clusters was discussed. The modelled results were in good agreement with the chamber measurements performed during the BIOFLUX campaign in September, 2003, in Mace Head, Ireland, confirming that I2 emissions and nucleation of iodine oxides can largely explain the coastal nucleation phenomenon.
Extractability and Transformation of Copper and Zinc Added to Tropical Savanna Soil under Long-Term Pasture

The extractability and slow reactions of copper (Cu) and zinc (Zn) in a weathered savanna soil under Brachiaria decumbens, Digitaria smutsii, and Stylosanthes guianensis pastures were determined in a laboratory incubation study using a sequential extraction to remove operationally defined fractions of the metals, consisting of exchangeable, organically bound, precipitate [occluded in aluminum (Al) and iron (Fe) oxides], and residual metal fractions. The soils from the pasture fields were spiked with 100 mg Cu kg–1 soil and 200 mg Zn kg–1 soil for 24 weeks. Copper and Zn extractable with 1 N potassium nitrate (KNO3) solution decreased exponentially with time but reached a steady state after 2–3 weeks. The concentrations of Cu and Zn exchangeable with potassium (K) were greater in the Digitaria smutsii field soil than Brachiaria decumbens and Stylosanthes guianensis field soils. The exchangeability of added Cu and Zn (indexed Mn+ (exch)) with time was described by a simple exponential decay equation: Mn+ (exch) = αeβt, where α is a constant, β is a coefficient that defines the rate of transformation of added Cu and Zn from the exchangeable to nonexchangeable pools, and t is time. The β values for Cu (0.040–0.076 mg kg–1 d–1) were almost 10 times greater than those of Zn (0.005–0.007 mg kg–1 d–1). Sequential extraction of added Cu and Zn indicated that between 26 and 30% of the total Cu and between 19 and 30% of the total Zn were associated with organic matter. Similarly, between 35 and 38% of total Cu and between 47 and 60% of total Zn were associated with Fe, Al, and manganese (Mn) oxides. The differential capacity of the pasture fields to transform added Cu and Zn from exchangeable and labile form to nonlabile and nonexchangeable form appears to be governed by organic matter (OM), pH, and active Fe ratio in the pasture field soils.
Emulsion polymerization of vinyl acetate initiated by intermittent γ radiation

The reaction kinetics of emulsion polymerization of vinyl acetate (VAc) monomer have been studied by using intermittent . gamma. radiation. The purpose of this technique is to take advantage of the polymerization reaction which still continues after the radiation production has been stopped, as expected by the Smith-Ewart rate theory. Tween 20 (polyoxyethylene sorbitan monolaurate), was used as the emulsifier. The polymer conversion was determined by using the dilatometric method. The polymerization rate R/sub p/ decreased with increase in emulsifier content. The Smith-Ewart rate theory cannot explain the experimental evidence satisfactorily. The average polymerization rate anti R/sub p/ between 20% and 80% conversion is a function of irradiation dose rate and can be written anti R/sub p/ = a/sub 1/I/sup a2/ where a/sub 1/ and a/sub 2/ is a constant in which the value depends on the emulsifier content in the emulsion and I is the irradiation dose rate.
The Fourier transform of actin and other helical systems with cumulative random angular disorder

A general class of helical disorder exists which can be described by cumulative random angular motions of subunits. This disorder affects layer-line intensities and widths by a factor proportional to n2, the square of the order of the layer line. The result explains several features of actin and polytetrafluoroethylene (Teflon) transforms, and may be relevant to other helical systems.
Poly(ethylene oxide)-based electrolytes for lithium-ion batteries

Poly(ethylene oxide) (PEO) based materials are widely considered as promising candidates of polymer hosts in solid-state electrolytes for high energy density secondary lithium batteries. They have several specific advantages such as high safety, easy fabrication, low cost, high energy density, good electrochemical stability, and excellent compatibility with lithium salts. However, the typical linear PEO does not meet the production requirement because of its insufficient ionic conductivity due to the high crystallinity of the ethylene oxide (EO) chains, which can restrain the ionic transition due to the stiff structure especially at low temperature. Scientists have explored different approaches to reduce the crystallinity and hence to improve the ionic conductivity of PEO-based electrolytes, including blending, modifying and making PEO derivatives. This review is focused on surveying the recent developments and issues concerning PEO-based electrolytes for lithium-ion batteries.
Simulation of global sulfate distribution and the influence on effective cloud drop radii with a coupled photochemistry sulfur cycle model

A sulfur cycle model is coupled to a global chemistry-climate model. The simulated surface sulfate concentrations are generally within a factor of 2 of observed concentrations, and display a realistic seasonality for most background locations. However, the model tends to underestimate sulfate and overestimate surface SO 2 at relatively polluted locations. A possible explanation for this is that additional oxidation reactions not considered in the model, may be important. Calculated tropospheric sulfate column abundances exceed those of previous studies, which is predominantly associated with a less efficient nucleation scavenging in wet convective updrafts. Through the simultaneous calculation of the sulfur cycle and tropospheric photochemistry, simulated H 2 O 2 and SO 2 concentrations are strongly linked, especially in polluted areas. The coupled model simulates a stronger oxidant limitation and, consequently, a smaller contribution to sulfate formation by H 2 O 2 oxidation of SO 2 when compared to sulfur cycle models that use monthly averaged oxidant distributions as input. In the polluted NH, the differences in calculated sulfate columns are largest in winter and relatively small in summer. Therefore, the coupling between the sulfur cycle and the oxidant chemistry is expected to have a minor impact on the calculation of the indirect and direct radiative forcing by sulfate. An empirical relation between sulfate concentration and cloud drop number concentration, derived from cloud measurements at Grean Dun Fell (UK), is applied to the simulated cloud and sulfate fields to derive distributions of effective could drop radii. Additionally, a relation between wind speed and cloud drop number concentration is applied over marine regions to account for the effect of seasalt aerosol on cloud formation when sulfate concentrations are relatively low. Calculated droplet radii are systematically underestimated by about 10–20% in the NH compared to satellite derived values, but they agree relatively well in the SH. DOI: 10.1034/j.1600-0889.1998. t01-2-00002.x
XPS Analysis of Polymer Membrane Degradation in PEMFCs

An important challenge for proton exchange membrane fuel cells (PEMFCs) is the stability and durability of the membrane separator. In this study, fluoride ion emission rates were determined from fuel cell durability tests at different temperatures. Degraded membranes were removed after each test, and both the anode and cathode sides of degraded membranes were analyzed by X-ray photoelectron spectroscopy (XPS). The results show that degradation was accelerated by high temperature and that the decomposition of both sulfonic acid side chains and the poly(tetrafluoroethylene) backbone occurred. The degradation was more severe on the anode side, showing that at least half of the side groups were decomposed there. A multilayer membrane electrode assembly was also used to study degradation at different locations especially in the bulk membrane, which illustrates that the degradation also occurs there but is slower than that at the anode side. This result also indicates that the rate of membrane degradation slows with thicker membrane. Finally, an improved kinetic model of membrane degradation was proposed to explain the experimental results.
Safety of Fresh Fruits and Juices Available on the Polish Market as Determined by Heavy Metal Residues

The content of Pb, Cd, Cu and Zn in fresh fruit and juices was determined using atomic absorption spectrometry (AAS) to determine the safety of some food available in the Polish market. It was found that most fruit samples (90.4%) contained low levels of heavy metals. However, the remaining 9.6% had increased heavy metal contents (Pb 2.2%, Cd 4.4%, Cu, 1.5%, Zn 1.5%). Most fruit juice sample (88%) met the national standard criteria, but 12% exceeded the permissible limits for Pb and Cd (3% and 9%, respectively). The results contained in this paper were presented in the 14th IGWT Symposium, Beijing, China, August 23-29, 2004.
Incorporation of luminescent lanthanide complex inside the channels of organically modified mesoporous silica via template-ion exchange method

Luminescent lanthanide complex, Eu(phen)2Cl3·2H2O (Euphen, phen = 1,10-phenanthroline) has been incorporated inside the channels of mesoporous silica MCM-41 with its external surface modified by phenyltriethoxysilane (Ph-Si(OEt)3) via a simple template-ion exchange method. The passivation of active groups such as silanols in the external surface ensures that the ion exchange reaction occurs between the surfactant cations and the lanthanide complex ions inside the channels of the modified MCM-41. The passivation result is confirmed by 29Si MAS NMR spectroscopy. FT-IR demonstrates that the cationic surfactants are completely removed. XRD and N2 adsorption–desorption measurements are employed to characterize the mesostructure of Euphen-Ph-MCM-41. Luminescence and stability studies on the materials of Euphen and Euphen-Ph-MCM-41 show that the resultant hybrid material Euphen-Ph-MCM-41 exhibits the characteristic emission of Eu3+ ions under UV irradiation with higher 5D0 luminescence quantum efficiency, longer lifetime and better thermal stability than the corresponding pure complex Euphen. Moreover, the characterization results show that the local symmetry and the first coordination shell of Eu3+ ions are changed after the complex ions become incorporated into the MCM-41 channels and that a more symmetric environment is occupied by the Eu3+ ions in Euphen-Ph-MCM-41 than in Euphen. There is also a more efficient ligand-to-Eu(III) intramolecular energy transfer process in Euphen-Ph-MCM-41.
The observation of large magnetite (Fe3O4) crystals from magnetotactic bacteria by electron and atomic force microscopy

Magnetite crystals inside coccoid magnetotactic bacteria found in lagoons near Rio de Janeiro city were examined by electron microscopy (EM) and atomic force microscopy (AFM). For AFM, ultrathin sections of bacteria embedded in Epon resin were etched with an ethanolic NaOH solution and observed both in the height and in the force modes. Comparative electron microscope images were useful for identifying crystalline reliefs in the etched sections. Different situations representing particular arrangements of crystal chains were observed by AFM. The majority of the bacteria examined presented unusually large magnetite crystals which remained strongly attached in linear chains even after the laboratory procedures for their isolation. This behaviour is different from all other biogenic magnetite crystals isolated so far. It is suggested that this attachment is due to the strong field between individual crystals as well as to the contact areas, which are the largest observed until now. The correct identification of a particular topography by AFM as a crystal relief may be critical when crystals are not aligned in chains; in these cases the linear dimensions and the presence of well‐defined edges and faces are important features to be taken into account. Characterization of the crystal faces is important for the study of magnetotactic micro‐organisms since the crystalline habits seem to be species‐specific. Observation of etched sections proved to be a helpful approach for crystal relief observation, especially when small amounts of bacteria were available.
Proton-Linked Protein Conformational Switching: Definition of the Alkaline Conformational Transition of Yeast Iso-1-ferricytochrome c‡

The alkaline conformation (state IV) of yeast iso-1-ferricytochrome c and variants in which selected lysyl residues were replaced with alanyl residues has been studied by 1H NMR spectroscopy, electronic spectroscopy, EPR spectroscopy, direct electrochemistry, pH-jump kinetics, and temperature-dependent circular dichroism spectroscopy. On the basis of the NMR studies, Lys73 and Lys79 are shown to replace Met80 as the axial ligand in the two conformers of state IV that were detected in previous studies (Hong, X. L.; Dixon, D. W. FEBS Lett. 1989, 246, 105−108; Ferrer, J. C.; Guillemette, J. G.; Bogumil, R.; Inglis, S. C.; Smith, M.; Mauk, A. G. J. Am. Chem. Soc. 1993, 115, 7507−7508). The pKa for the conformational equilibrium between state III (native conformation) and state IV of the wild-type protein (8.70(2)) is found to be intermediate between that of the Lys73 bound conformer (8.44(1)) and that of the Lys79 bound conformer (8.82(2)) (0.1 M NaCl, 25 °C) as are the kinetic parameters for the conversion o.
Generalized van der Waals theories and the asymptotic form of the density profile of a liquid–vapor interface

Generalized van der Waals theories for the free energy and density profile of an inhomogeneous fluid are used to obtain an expression for the tails of the density profile of a liquid–vapor interface of an argon‐like fluid. We find that the density profile decays asymptotically into the bulk regions as the inverse cubed power of the distance from the center of the interface. We estimate the effect to be too small to be quantitatively significant.