Miracle-dz/UniFAR-FTUs huggingface dataset:
Study of the solubility of amorphous and crystalline uranium dioxide by combined spectroscopic methods

Colloid formation and solubility of U(IV) in acidic HClO4/NaClO4 solutions are investigated by coulometric titration. Quantification of traces of U(VI) by laser fluorescence spectroscopy proves that the tetravalent state of uranium had been maintained. Laser-induced breakdown detection (LIBD) is applied for the detection of traces of uranium colloids as the pH is increased. The pH values at the onset of colloid formation are used for thermodynamic calculations aimed at determining the solubility products K°sp of crystalline and amorphous uranium dioxides. The particle size of the colloids determined by means of LIBD is taken into account since it influences the solubility product. The results indicate the formation of crystalline UO2(cr) at low pH∼1 (logK°sp= -59.6±1.0) whereas the amorphous hydrous oxide UO2·xH2O(am) is formed at pH ∼ 3 (logK°sp = -54.1 ± 1.0). Measurements by EXAFS, XRD and REM confirm the occurrence of these different phases. The obtained solubility products fit well in the known series of solubility products of the other tetravalent actinides.
Radionuclide Retention in Concrete Waste Forms

Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. The information present in the report provides data that (1) measures the effect of concrete wasteform properties likely to influence radionuclide migration; and (2) quantifies the rate of carbonation of concrete materials in a simulated vadose zone repository.
The electronic structure of polyhex carbon tori

The π-orbital electronic structure of polyhex carbon tori constructed from bent individual single-wall nanotubes is investigated within the tight-binding approach. Analytical solutions for tori from nanotubes of arbitrary radius, length, chirality, and twisting angle are derived using simple geometrical and band-structure arguments. Vanishing of the gap between highest occupied and lowest unoccupied molecular orbitals for a torus imposes divisibility by 3 on the indices of chiral and twisting vectors, which translates into one graph-theoretical condition: a metallic polyhex torus is constructible as a leapfrog transformation of a smaller polyhex torus.
Extended deep-level defects in MBE-grown p-type CdTe layers

Five deep-level hole traps, associated with native defects, have been revealed by means of deep-level transient spectroscopy in p-type CdTe layers grown on highly mismatched GaAs substrate by the molecular-beam epitaxy technique. Two of the traps have been attributed to the electronic states of dislocations on the ground of the logarithmic capture kinetics for capture of holes into the traps states. The images taken by transmission electron microscopy show that they are probably threading dislocations of 60°-type, generated at the mismatched interface with the substrate. One trap, which was observed only when the investigated space charge region was close to the metal–semiconductor interface, has been assigned to surface defect states. The last two traps, displaying exponential capture kinetics, have been ascribed to native point defects: the Cd vacancy and a complex formed of Cd vacancy and Te antisite, produced during the epitaxial growth of the CdTe layers. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Cloud droplet activation mechanisms of amino acid aerosol particles: insight from molecular dynamics simulations

Atmospheric amino acids constitute a large fraction of water-soluble organic nitrogen compounds in aerosol particles, and have been confirmed as effective cloud condensation nuclei (CCN) materials in laboratory experiments. We present a molecular dynamics (MD) study of six amino acids with different structures and chemical properties that are relevant to the remote marine atmospheric aerosol–cloud system, with the aim of investigating the detailed mechanism of their induced changes in surface activity and surface tension, which are important properties for cloud drop activation. Distributions and orientations of the amino acid molecules are studied; these l-amino acids are serine (SER), glycine (GLY), alanine (ALA), valine (VAL), methionine (MET) and phenylalanine (PHE) and are categorised as hydrophilic and amphiphilic according to their affinities to water. The results suggest that the presence of surface-concentrated amphiphilic amino acid molecules give rise to enhanced Lennard–Jones repulsion, which in turn results in decreased surface tension of a planar interface and an increased surface tension of the spherical interface of droplets with diameters below 10 nm. The observed surface tension perturbation for the different amino acids under study not only serves as benchmark for future studies of more complex systems, but also shows that amphiphilic amino acids are surface active. The MD simulations used in this study reproduce experimental results of surface tension measurements for planar interfaces and the method is therefore applicable for spherical interfaces of nano-size for which experimental measurements are not possible to conduct.
Crescimento de meloeiro sob estresse salino e doses de potássio

O Estado do Rio Grande do Norte, em destaque a regiao da Chapada do Apodi, se destaca na producao e exportacao de melao no Pais, em regime de irrigacao, devido a distribuicao pluvial baixa e irregular. A Chapada do Apodi possui dois aquiferos subterrâneos; a do lencol menos profundo de alta salinidade, porem com menor custo de bombeamento, ocorrendo o contrario com o de maior profundidade. Objetivou-se, ante o exposto, avaliar o efeito de duas aguas de salinidades diferentes (0,52 e 2,41 dS m-1), combinadas com cinco doses de K2O (218, 273, 328, 383 e 438 kg ha-1) sobre o crescimento do meloeiro (Cucumis melo L.), cultivar Goldex, utilizando-se do delineamento de blocos ao acaso, com parcelas subdivididas; amostras de planta foram coletadas aos 21, 28, 35, 49 e 63 dias apos a semeadura, determinando-se a fitomassa seca das plantas, estas separadas em ramos (caule + folhas), flores e frutos; avaliou-se, tambem, a taxa de crescimento absoluto e relativo e a producao de frutos. Em geral, o crescimento do melao foi favorecido com o uso de agua mais salina; a taxa de crescimento absoluto foi maxima entre 35 e 49 dias apos a semeadura. Obteve-se maior producao de fitomassa total com 438 kg ha-1 de K2O e uso de agua mais salina, ao final do ciclo.
Influence of Secondary Reactions on the Heat of Pyrolysis of Biomass

The thermal behaviors during the pyrolysis of two different biomass samples, beech wood from carpentry residuals and artichoke thistle from energy-dedicated crops, were investigated. Thermogravimetry/differential scanning calorimetry (TG-DSC) and thermogravimetry coupled to Fourier transform infrared (TG-FTIR) analysis of evolving products were used to investigate the thermal effects of the pyrolysis process. The role of pretreatments (hot-water washing, ethanol extraction, and their combination) was also analyzed. High alterations in the heat demand were observed as a function of the initial sample mass and pyrolysis conditions. The role of vapor−solid secondary interactions was evidenced by the evolution profiles of the main pyrolysis products.
Pore-size dependence of the self-diffusion of hexane in silica gels

Quasielastic neutron scattering has been used to investigate the diffusion of hexane molecules adsorbed in mesoporous silica gels with pore diameters of 20, 40, and 60 A, respectively. Within the temperature range 180 K⩽T⩽240 K molecular reorientations, which are best described by a tumbling rod, and translational diffusion of the molecular center of mass could be observed. In each investigated sample two different environments were identified for the adsorbed molecules: the vicinity of the pore walls and the center of the pores. The hindering potentials for both translation and rotation are found to be considerably stronger for the molecules on the pore walls. The fraction of this molecule type decreases with increasing pore size. The self-diffusion coefficients derived from our data range from Dtrans=0.6 to 2.4×10−6 cm2 s−1. The activation energies of the translational diffusion are within the range 139 meV⩽Ea⩽302 meV. They decrease with increasing pore size with a clear tendency towards the activation .
Estimating the Hydraulic Conductivity of Landfilled Municipal Solid Waste Using the Borehole Permeameter Test

This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at a landfill in Florida. The saturated hydraulic conductivity ( Ks ) was estimated at 23 locations using the borehole permeameter test, a method commonly used for determination of the Ks of unsaturated soil. The Ks of the landfilled waste was found to range from 5.4× 10−6 to 6.1× 10−5 cm∕s . The Ks was found to be on the lower end of the range of Ks reported by previous studies. The hydraulic conductivity of the waste decreased with depth, the likely result of greater overburden pressures associated with deep locations of the landfill. Permeability values ( kw ) of the landfilled waste calculated based on Ks were compared with permeability values estimated using air as the fluid (air permeability, ka ). Values of ka were found to be approximately three orders of magnitude greater than those of kw . The lower permeability of the waste to water was primarily attributed to entrapped gas. Other factors such as pote.
Nanoparticles produced by laser ablation of solids in liquid environment

A review of results on nanoparticles formation is presented under laser ablation of Ag, Au, and Ti solids targets in liquid environments (H2O, C2H5OH, C2H4Cl2, etc.). X-ray diffractometry (XRD), UV-Vis optical transmission spectrometry, and high-resolution transmission electron microscopy (HRTEM) characterise the nanoparticles. The morphology of nanoparticles is studied as a function of both laser fluence and nature of the liquid. The evidence of an intermediate phase of Au-Ag alloy is presented under exposure of a mixture of individual nanoparticles to laser radiation. Self-influence of the beam of a femtosecond laser is discussed under the ablation of the Ag target in liquids under Ti:sapphire laser. The factors are discussed that determine the distribution function of particle size under laser ablation. The influence of laser parameters as well as the nature on the liquid on the properties of nanoparticles is elucidated.
Calculation of the Optimal Macropore Size in Nanoporous Catalysts and Its Application to DeNOx Catalysis

Macropores act as broad highways for molecules to move in and out of a nanoporous catalyst. The macropore “distributor” network in such a hierarchically structured porous catalyst, containing both nanopores and macropores, is optimized with the aim to find the optimal effectiveness factor, ηopt, of a single reaction with general kinetics in the catalyst. Molecular diffusion is assumed to dominate transport in macropores. It is found that the ηopt−Φ0 relation qualitatively recovers the universal η−Φ relation when the generalized distributor Thiele modulus, Φ0, is defined in a way analogous to the generalized Thiele modulus, Φ, but using the molecular diffusivity in the macropores rather than the effective diffusivity in the nanopores. This is because the concentration gradient inside the optimal hierarchically structured, porous catalyst exists only in one principle direction (e.g., the radial direction in a spherical catalyst particle), and molecular diffusion in the macropores dominates the transport pro.
Applying the linear equation of correlation of Brunauer‐Emmet‐Teller (BET)‐monolayer moisture content with temperature

The linear equation describing the correlation of BET-monolayer moisture content with temperature has been applied for a large group of products of various origin and properties. It has been established that for most materials there exists a high linear correlation between these two values, and the dependence betwenn them is described with sufficient accuracy by the coresponding linear equation.
Estimation of Bite Angle Effect on the Electronic Structure of Cobalt-Phosphine Complexes: A QTAIM Study

The influence of bite angle in bisphosphine complexes has been modeled by DFT calculations employing the simple model compound HCo(CO)(PP) (PP = Xantphos or two monophosphine ligands). The increase of the bite angle increases the strength of the H–Co bond, whereas the C–O bond in the carbonyl ligand is weakened revealing an increase also in the donor character. The model compound cis-[HCo(CO)(PPh3)2] shows a flexibility both in terms of energy, and in terms of electronic structure upon the change of the P-Co-P angle, which can be a sign of the flexibility of PPh3 ligands in real reaction conditions.
Acceleration of Synthetic Organic Reactions Using Supercritical Water: Noncatalytic Beckmann and Pinacol Rearrangements

A high-pressure and high-temperature FTIR was used to study noncatalytic Beckmann and pinacol rearrangements using supercritical water (scH2O). Significant acceleration of Beckmann and pinacol rearrangements can be achieved by using scH2O, especially near the critical point, even in the absence of any acid catalysts. It has been demonstrated that scH2O acts effectively in the place of conventional acid catalysts for both the rearrangements. The rate of pinacol rearrangement using scH2O is significantly larger by a factor of 28200 than that in 0.871 M HCl solution at 46.7 MPa under distillation conditions. The activation energy for the former at 25 MPa was found to be markedly reduced to about one-third of that for the latter. The accelerated rates of reaction may be attributed to a great increase in the local proton concentration around the organic reactants. In addition, the nature of scH2O can be adjustable to weak acidity in the near-critical region, and then it does not catalyze the pinacol rearrangem.
Synthesis and Structure of a Novel Cu(II) Complex with a Monoprotic Tetradentate Schiff Base Ligand

Reaction of copper(II) chloride with an unsymmetrical tetradentate (NNNO) Schiff base ligand, N-(2-pyridylmethyl)-N‘-(salicyaldimino)-1,3-propanediamine (Hpaip), was investigated as a possible route to a square-planar monocationic copper radiopharmaceutical. In the solid state the [Cu(paip)Cl] complex was found to instead adopt a square-pyramidal geometry with the deprotonated tetradentate ligand in the basal plane and a weakly bound chloride ligand in the apical position.
The Nucleation of Ice Formation by Silver Iodide

Silver iodide particles have been found to serve as nuclei for the formation of ice crystals in super‐cooled water and in water vapor super‐saturated with respect to ice. It is believed that silver iodide serves as a very effective nucleus because it very closely resembles ice in crystal structure. Both dimensions of the unit cell of ice and silver iodide are the same to within approximately one percent. The maximum temperature at which the silver iodide particles serve as nuclei is approximately −4°C for particles one micron in diameter, and −8°C for particles 100 Angstrom units in diameter. A silver iodide smoke generator has been constructed which consumes 1 mg of silver iodide per second and produces 1013 effective nuclei per second.
Synchronization, waves, and turbulence in systems of interacting chemical oscillators

The aim of this thesis is to investigate systems of interacting nonlinear oscillators. We analyze nonlocally coupled oscillators where the interaction among the dynamical units is longranged and distance-dependent. In the proposed model, the oscillatory dynamics are given by the complex Ginzburg-Landau equation, which provides a general description of reactiondiffusion systems close to the Hopf bifurcation. The system is further coupled to a passive component which is diffusing as well, and inertial. This second field has a much larger diffusion constant than the first one, thus it provides an effective nonlocal coupling. The single oscillator-system displays birhythmicity, i.e. the coexistence of two stable limit cycles with different amplitudes and frequencies. Linear stability analysis of the phase approximation of the extended system shows that the two limit cycles have different stability properties against propagation of weak perturbations. Numerical solution of the equations displays patterns such as uniform oscillations, phase and amplitude turbulence, spiral breakup, bursts of synchronization, and bursts of desynchronization. We suggest that, besides the known oscillatory phenomena in biology such as glycolytic oscillations and calcium waves, a novel type of self-organized spatio-temporal behavior could arise from synchronization among enzyme molecules. We propose a system of product-activated allosteric enzymes interacting through diffusion of small product molecules with regulatory function. We describe an enzyme as a phase oscillator: An individual catalytic event is a circular motion in the enzyme’s conformational space. This sequence of structural changes allows conversion of one substrate molecule into one product molecule. The released product can then either bind to another enzyme and regulate its activity, or decay. This feedback mechanism causes synchronization of the enzymatic cycles, resulting in oscillations of the product concentration on the time scale of the duration of an individual catalytic reaction. The enzyme population can also split into clusters. In the extended system where product diffusion does not allow complete mixing, a codimension-2 Hopf-wave bifurcation is found. Numerical simulations reveal the existence of patterns such as standing and travelling waves, ripples, pacemakers, and spirals.
A Multi-Solid Phase Thermodynamic Model for Predicting Wax Precipitation in Petroleum Mixtures

Abstract The precipitation of waxy constituents in petroleum mixtures subjected to a cold environment gives rise to a variety of problems well-known in the petroleum industry. A revised multi-solid phase thermodynamic model for predicting wax precipitation in petroleum mixtures is presented in this article. The Peng-Robinson equation of state is used to evaluate the phase behavior of both liquid and vapor phases. The results predicted by this model agree with the experimental data of wax precipitating for several synthetic oils and crudes.
Rational synthesis of ZnMn2O4 porous spheres and graphene nanocomposite with enhanced performance for lithium-ion batteries

Currently, tremendous efforts have been focused on developing high-performance anode materials for lithium-ion batteries (LIBs). In this work, we develop an effective strategy to synthesize a nanocomposite of ZnMn2O4 porous spheres and graphene (ZMO-G PSs) as an advanced anode material for high-performance LIBs. SEM and TEM characterizations reveal that the ZMO PSs are tightly wrapped by graphene sheets and uniformly distributed within the graphene matrix. Owing to the rational combination of the merits of both ZMO PSs and graphene, the as-prepared ZMO-G PSs nanocomposite exhibits significant enhanced LIB performance with high reversible capacity, long cycle life and good rate performance. Remarkably, the nanocomposite exhibits a high reversible capacity of 926.4 mA h g−1 after 100 cycles at a current density of 200 mA g−1, which is much higher than that of pure ZMO PSs (493.3 mA h g−1). Moreover, a high capacity of 560.8 mA h g−1 can be retained at a high current density of 1200 mA g−1. These electrochemical results suggest the ZMO-G PSs nanocomposite could be a promising anode material in energy storage applications for high-performance LIBs.
Influence of Solvent on the Spectroscopic Properties of Cyano Complexes of Ruthenium(II)

UV−visible spectra, emission spectra, and RuIII/II reduction potentials have been measured for cis-[Ru(bpy)2(py)(CN)]+ (bpy is 2,2‘-bipyridine; py is pyridine), cis-Ru(bpy)2(CN)2, [Ru(tpy)(CN)3]- (tpy is 2,2‘:6‘,2‘‘-terpyridine), [Ru(bpy)(CN)4]2-, and [Ru(MQ+)(CN)5]2- (MQ+ is N-methyl-4,4‘-bipyridinium cation) in twelve solvents. The shifts in the metal-to-ligand charge transfer (MLCT) absorption (Eabs) or emission (Eem) band energies with solvent increase linearly with the number of cyano ligands and correlate well with the Gutmann “acceptor number” of the solvent. Intraligand π → π* band energies also correlate with acceptor number, but with only ∼30% of the shifts for the MLCT bands. The solvent dependence arises through mixing of the π → π* transitions with lower energy MLCT transitions. MLCT absorption and emission spectra are convolutions of overlapping vibronic components, and a Franck−Condon analysis of emission spectral profiles for cis-Ru(bpy)2(CN)2* has been used to evaluate the energy gap, E0,.
Parallel transport of BSA by surface and pore diffusion in strongly basic chitosan

The parallel transport of a protein by surface and pore diffusion within a highly porous ion exchanger is studied by measuring equilibria and uptake curves for adsorption of bovine serum albumin (BSA) on two different strongly basic chitosan ion exchangers (hard gels): Ch-2503 and Ch-2507 at pH 6.9 and 298 K. Experimenlal equilibrium isotherms are correlated by the Langmuir equation. Intraparticle effective diffusivities of BSA (D eff ) are determined from the homogeneous Fickian diffusion model, increasing with the bulk phase concentration increase of BSA (Co). It suggests the existence of parallel diffusion. The surface diffusivity D s for the parallel diffusion model is determined from the D eff , and D s =0.47X10 -13 m 2 /s (Ch-2507) and 2.4X10 -13 m 2 /s (Ch-2503) were obtained. Pore diffusivities based on the pore diffusion control (D' p ) are obtained by matching the shrinking core model with the experimental uptake curves. D' p decreases with increasing C 0 . Since D' p in Ch-2507 is constant when c 0 ≥1 kg/m 3 , the constant value 2.7X10 -11 m 2 /s is taken as the accurate pore diffusivity (D p ). As D' p in Ch-2503 does not approach a constant value, D p =1.0X10 -11 m 2 /s is determined by matching the parallel diffusion model with the uptake data, and the model calculated using experimental values of D s and D p agrees reasonably well with the uptake data for Ch-2507 and Ch-2503. This theoretical approach may be applied not only for intraparticle diffusion of proteions but any adsorbates in porous materials
Wpływ popiołu ze słomy rzepaku ozimego na pH oraz zawartość przyswajalnych makroelementów (P, K, Mg) i mikroelementów (B, Cu, Mn, Zn, Fe) w glebie lekkiej

Synopsis. W Stacji Badawczej w Mochełku (53°13′ N, 17°51′ E), należącej do Uniwersytetu Technologiczno-Przyrodniczego w Bydgoszczy przeprowadzono doświadczenie wazonowe, którego celem było określenie zmian pH oraz zawartości przyswajalnych dla roślin P, K, Mg, B, Cu, Mn, Zn i Fe pod wpływem popiołu ze słomy rzepaku ozimego, stosowanego w dawkach odpowiadających 0,0 – 8,0 t∙ha-1. Wazony wypełniano glebą o składzie piasku gliniastego. Stwierdzono, że popiół ze słomy rzepaku ozimego w ilości równoważnej 1,0 – 2,0 t∙ha-1zwiększył zawartość przyswajalnych form makroi mikroelementów w glebie nawet o kilkanaście, kilkadziesiąt procent. Istotne zwiększenie wartościpH gleby o odczynie lekko kwaśnym wymagało aplikacji popiołu ze słomy rzepaku w dawce conajmniej 2,0 t∙ha-1. Efekt wprowadzenia do gleby popiołu ze słomy rzepaku ozimego utrzymywał się przez 120 dni od aplikacji. Jedynie zawartość przyswajalnych dla roślin potasu magnezu i żelaza zmniejszała się w czasie.