Miracle-dz/UniFAR-FTUs huggingface dataset:
Numerical calculation of the rate of crystal nucleation in a Lennard‐Jones system at moderate undercooling

We report a computer‐simulation study of the rate of homogeneous crystal nucleation and the structure of crystal nuclei in a Lennard‐Jones system at moderate undercooling. The height of the nucleation barrier has been determined using umbrella sampling, whereas the barrier crossing rate is calculated using molecular dynamics simulation. The simulations clearly show that the barrier crossing is a diffusive process. Nevertheless, the kinetic prefactor in the nucleation rate is found to be some two orders of magnitude larger than predicted by classical nucleation theory. The height of the barrier is in good agreement with the theoretical prediction. Although the Lennard‐Jones system has a stable face‐centered cubic (fcc) phase below the melting line, the precritical nuclei are found to be mainly body‐centered cubic (bcc) ordered. As they grow to their critical size, they become more fcc ordered in the core. However, the critical and postcritical nuclei retain a high degree of bcc ordering in the interface. F.
Syntheses for the deconvolution of the Patterson function. IV. Refinement of the theory and a general comparison of the various syntheses

The details of the γ class of syntheses are given in this paper. The theory of the standard syntheses namely, |F|, exp[iα], exp[2iα], 1/|F| and 1/F is refined to the next higher order of approximation. The results are then applied to work out the ratio ρ of the strength of the peak at the unknown to that at the known atomic positions in the α, γ, α', β' and γ' syntheses. Finally a general comparison of the various syntheses is made using the above ratio as the criterion for judging their relative merits.
Predicting Analog Forecasting Errors using Dynamical Systems

—Nearest neighbor algorithms called Analog Forecasting have been used to produce short-range to long-range forecasts in many atmospheric and oceanic applications. Analog Forecasting is often treated as a purely empirical method, independent from physical equations. In this paper, we investigate Analog Forecasting error from a dynamical systems point of view. Assuming that analogs follow the same dynamics as the system of concern, we evaluate statistical properties of Analog Forecasting errors. We further design dynamics-based systematic error correction methods for standard Analog Forecasting techniques. These procedures are tested on the 3-dimensional Lorenz-63 system.
Preparation of long-chain branching polypropylene and investigation on its foamability

In this work, zinc N,N-dimethyldithiocarbamate (ZDMC) was used to mediate the melt modification of polypropylene (PP) with 1,6-hexanediol diacrylate (HDDA) in an internal mixer in the presence of dicumyl peroxide (DCP). Fourier transformed infrared spectroscopy analysis revealed that HDDA was directly grafted onto PP backbone. The dependence of torque on processing time indicated that the presence of ZDMC restrained the degradation of PP, and the end-torque value increased with the addition of ZDMC. Dynamic rheological measurement indicated that the modified PP possessed higher G′ and lower tan δ at low frequency, displaying an increase in η* and disappearance of Newtonian plateau in η*–ω plot, as well as larger radius of semicircle in Cole–Cole plot. All the rheological characterizations, together with the decreased gel content with the increase of ZDMC, confirmed the formation of long-chain branching. Subsequently, the foamability of the modified samples was investigated by one-step compression–molding process. The cellular structure and morphology of the obtained foams were observed by scanning electron microscopy, and the results showed that the addition of ZDMC decreased the cell size, increased the cell density, and brought about well-defined closed cell structure. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Comparing the Effect of Chemical and Physical Properties on Complex Electrical Impedance of Scots Pine Wood

Summary This study examined the effects of physical (moisture content, water content and wood density) and chemical properties (concentration of phenolics and resin acids) on the electrical properties of Scots pine (Pinus sylvesteris L.) wood specimens. Complex impedance was measured from heartwood and sapwood specimens using frequencies between 5 kHz and 1 MHz. Significant correlation between density and electrical properties was found at high frequencies with sapwood specimens in which the extractive content was low. Moisture content had an effect on electrical properties over the whole frequency range. Electrical properties of heartwood samples with high extractive content were differently affected by the chemical and physical properties. Electrical properties were sufficient to distinguish between the samples from the brown-rot resistant and susceptible Scots pine trees.
Mass transport in a novel two‐fluid taylor vortex extractor

Flow instabilities occurring in rotating flows can be exploited as a new approach to liquid-liquid extraction. Two immiscible liquids are radially stratified by centrifugal force in the annulus between corotating coaxial cylinders. When the inner cylinder is rotated above a critical speed, Taylor vortices form in one or both of the fluids. Although the flow pattern yields a relatively small amount of interfacial surface area, the surface is highly active for interphase mass transfer due to the local vortex motion. By adding countercurrent axial flow, efficient continuous processing is also possible. This flow yields a viable extraction process, particularly for fluid pairs that are easily emulsifiable and therefore have limited processing options with the current equipment commercially available. This article demonstrates that two-fluid Taylor-Couette flow with countercurrent axial flow is achievable in practice and explores, experimentally and computationally, the mass-transfer characteristics of the flow. Experimentally, when the vortices first appear, axial dispersion decreases and the interphase mass transfer starts to increase. Upon further increase in differential rotation rate, the extraction performance continues to improve, with the mass-transfer coefficient proportional to the strength of Taylor vortices. This suggests that very high extraction efficiencies can be obtained with even larger relative rotation rates. Furthermore, mass-transfer boundary-layer theory, in combination with computational fluid dynamics, provides a reliable method for predicting the extraction performance.
Capacitively coupled plasma used to simulate Titan's atmospheric chemistry

A complex chemistry in Titan's atmosphere leads to the formation of organic solid aerosols. We use a radio-frequency (RF) capacitively coupled plasma discharge produced in different N2–CH4 mixtures (from 0% to 10% of CH4) to simulate this chemistry. The work presented here was devoted to the study of the plasma discharge. In our experiment, the electron density is measured by the resonant cavity method and is about 1015 m−3 in pure N2 plasma at 30 W excitation RF power. It decreases by a factor of 2 as soon as CH4 is present in the discharge, even for a proportion as small as 2% of CH4. An optical emission spectroscopy diagnostic is installed on the experiment to study the evolution of the N2 bands and to perform actinometry measurements using Ar lines. This diagnostic allowed us to measure variations in the electron temperature and to show that a decrease in the density of the electrons can be compensated by an increase in their energy. We have also used an experimental setup where the plasma is tuned in a pulsed mode, in order to study the formation of dust particles. We observed variations in the self-bias voltage, the RF injected power and the intensities of the nitrogen bands, which indicated that dust particles were formed. The characteristic dust formation time varied, depending on the experimental conditions, from 4 to 110 s. It was faster for higher pressures and for smaller proportions of CH4 in the gas mixture.
Nitrogen-induced improvement of resistive switching uniformity in a HfO2-based RRAM device

The effect of nitrogen doping by the NH3 plasma treatment approach on the resistive switching properties of a HfO2-based resistive random access memory (RRAM) device is investigated. Test results demonstrate that significantly improved performances are achieved in the HfO2-based RRAM device by nitrogen doping, including low operating voltages, improved uniformity of switching parameters, satisfactory endurance and long retention characteristics. Doping by nitrogen is proposed to suppress the stochastic formation of conducting filaments in the HfO2 matrix and thus improve the performances of the Pt/Ti/HfO2/Pt device.
Soil analysis procedures using 0.01 M calcium chloride as extraction reagent

Abstract This publication gives details of laboratory procedures for the determinations of bioavailable (e.g., plants) quantities of nutritional and polluting inorganic elements in 0.01 M CaCl2 extracts of air‐dry soil samples. Air‐day soil samples are extracted for two hours with a 0.01 M CaCl2 solution of 20°C in a 1:10 extraction ratio (W/V). After measuring the pH in the settling suspension, the concentrations of nutritional and polluting elements are measured in the clear centrifugate or filtrate. The procedure is simple, easy to perform, and cheap (labor, chemicals) in daily use in routine soil laboratories. The method receives internationally more and more attention as an alternative for the many extraction procedures for a single nutrient or pollutant that are still in use nowadays. The soil is extracted with a solution what has more or less the same ionic strength as the average salt concentration in many soil solutions. Various nutrients and metals can be measured in a single extract that allows considering relationships between them during interpretation of the data. For most elements, different detection techniques are described in detail in this publication. Detailed laboratory procedures are described for the determination of pH, total dissolved organic carbon, nitrate, ammonium, total dissolved nitrogen, sulphate, total dissolved sulfur, ortho‐phosphate, total dissolved phosphate, sodium, potassium, magnesium, cadmium, copper, nickel, lead, aluminum, iron, arsenic, boron, and phenols. Since only one extract of soil samples is used, profitable use can be made of multi‐element detection techniques like segmented‐flow analysis spectrometry, ICP‐OES, and ICP‐MS.
Positron age-momentum correlation (AMOC) measurements on organic liquids

By means of correlated measurements of the individual lifetimes of positrons (called positron ages) and of the Doppler shifts of their 2 γ-annihilation radiation ( Age-Momentum Correlation, acronym AMOC) the room-temperature behaviour of positrons and positronium in n-hexane, tetramethylsilane, benzene, methanol, ethanol, nbutanol, n-hexanol, n-octanol, and water has been investigated. The annihilation parameters of “ free” positrons and of para- and orthopositronium (lifetimes and Doppler-broadened lines) have been deduced from a two-dimensional analysis of the AMOC data. The lifetimes of positrons are found to be related to the electronic polarizability of the investigated liquid. The behaviour of the Doppler-broadened free-positron and orthopositronium linewidths is explained in terms of structural and dipolar properties of the liquid molecules.
Concentration Dependence of the Flory χ Parameter within Two-State Models

The Flory χ parameter is typically assumed to depend only on the temperature, T. Experimental results often require the replacement of this χ(T) by χeff, which depends also on the monomer volume fraction, φ, χeff(φ,T). Such χeff(φ,T) can arise from two-state models, proposed for polyetheleneoxide (PEO) and other neutral water-soluble polymers. The predicted φ dependence of χ = χeff − (1 − φ)∂χeff/∂φ, obtainable from colligative properties, differs qualitatively between the various models: (i) The model of Karlstrom (J. Phys. Chem. 1985, 89, 4962) yields ∂χ/∂φ ≥ 0 while the model of Matsuyama and Tanaka (Phys. Rev. Lett. 1990, 65, 341) and of Bekiranov et al. (Phys. Rev. E 1997, 55, 577) allows for ∂χ/∂φ < 0. (ii) χ(φ) as calculated from the Karlstrom model, utilizing the parameters used to fit the phase diagram of PEO, agrees semiquantitatively with the experimental values. On the other hand, χ(φ) similarly calculated from the model of Bekiranov et al. differs qualitatively from the measured results. Alt.
SIMULTANEOUS DETERMINATION OF P-HYDROXYBENZOIC ACID, 2-PHENOXYETHANOL, METHYL-P-HYDROXYBENZOATE, ETHYL-P-HYDROXYBENZOATE, PROPYL-P-HYDROXYBENZOATE, ISO-BUTYL-P-HYDROXYBENZOATE, AND N-BUTYL-P-HYDROXYBENZOATE IN SENSELLE LUBRICANT FORMULATION BY HPLC

A new and simple reversed-phase high-performance liquid chromatographic (HPLC) method has been developed and validated for the simultaneous determination of p-hydroxybenzoic acid, 2-phenoxyethanol, methyl-p-hydroxybenzoate, ethyl-p-hydroxybenzoate, propyl-p-hydroxybenzoate, iso-butyl-p-hydroxybenzoate and n-butyl-p-hydroxybenzoate preservatives in senselle lubricant formulation. The seven compounds were separated on a C18 ChromSpher polymeric octadecylsilane (ODS)-encapsulated spherical silica column with acetonitrile-tetrahydrofuran-water, 22:14:64 (v/v/v) as mobile phase at flow rate of 1.5 mL/min. The analysis was performed with ultraviolet (UV) detection at 258 nm. The analysis time was <15 min. The method was validated with respect to linearity, precision, accuracy, selectivity, specificity, and limits of detection and quantitation. The calibration curves showed good linearity over the concentration range of 5.4–217 µg/mL. The correlation coefficients were ≥0.9996 in each case. The relative standard deviation (RSD) values for intra- and inter-day precision studies were <1%. The procedure describe here is simple, selective, and is suitable for routine quality control analysis and stability tests.
Production and Detection of H Atoms and Vibrationally Excited H2 Molecules in CVD Processes

Radical species, including atomic hydrogen, play an important role in the CVD process to prepare high-quality thin solid films. Detailed information on the absolute densities of these radicals under various conditions is needed in order to understand the chemical kinetics involved and to control the deposition processes. This article reviews the production mechanisms and the gas-phase diagnostic techniques for H atoms in catalytic CVD (also called hot-wire CVD) and plasma-enhanced (PE)CVD processes. Experimentally determined absolute H-atom densities in typical CVD processes are compiled in a table. Under suitable conditions, the steady-state H-atom density can be increased up to 1017 cm−3. Procedures for producing and detecting vibrationally excited H2 molecules, which can be another active species in CVD processes, are also discussed.
THE CRYSTAL STRUCTURE OF NEYITE, Ag2Cu6Pb25Bi26S68

The crystal structure of type neyite from Alice Arm, British Columbia, was determined from single-crystal X-ray diffraction data with the agreement factors R 1 = 0.037 (0.072 for all) and ω R 2 = 0.078. The structural formula supported by the new electron-microprobe data is AgCu 3 Pb 12.5 Bi 13 S 34 ( Z = 4); the lattice parameters are a 37.527(6), b 4.0705(6), c 43.701(7) A, β 108.801(2)°, space group C 2/m . The structure contains 26 independent large-cation polyhedra, one Ag site and three Cu sites. It can be described as an alternation of triple-octahedron (111) PbS -like layers with (100) PbS -like layers two atomic planes thick. Both sets of layers are (a) sheared, giving rise to tetrahedral Cu sites, and (b) truncated by wavy PbS-like layers (001) ney , three atomic planes thick. The resulting structure can be described as a box-work of (100) PbS -like layers enclosing (111) PbS -like fragments. Several hypothetical structures based on the neyite principle have been derived.
Physiological Effects of Salicylic Acid and Thiourea on Growth and Productivity of Maize Plants in Sandy Soil

This study aimed to investigate the response of vegetative growth, yield, and some metabolic constituents of maize grains cv. Single Cross 124 to foliar applications of salicylic acid (SA; 100, 200, and 400 mg L−1) and thiourea (TU; 500, 1000, and 1500 mgL−1), two bioregulators, either alone or in combination. The foliar application of SA and TU alone significantly increased stem diameter, number of leaves / plant, leaf area, total dry weight / plant, leaf area index, net assimilation rate, specific leaf weight, and yield (i.e., ear length, ear diameter, number of grains / row, number of rows / ear, 100-grain weight, grain yield / plant, grain yield / fed (1 feddan = 4200 m2), harvest index, and shelling percentage) by increasing SA or TU concentrations up to 200 and 1500 mg L−1, respectively. Salicylic acid and TU, when applied alone, significantly improved the nutritional value and quality of maize grains by increasing crude protein, total soluble sugars, total free amino acids, and total soluble phenols.
Synthesis and characterization of highly dispersed molybdenum species in SBA-15 mesoporous molecular sieves

An original pathway involving H2O2 is described for the incorporation of highly dispersed molybdenum oxo species into the mesoporous network of an SBA-15 type silica. This procedure requires a mixture of templating agents: the triblock copolymer EO20PO70EO20 and the quaternary ammonium salt CTMACl, which are commonly used for SBA-15 and MCM-41 syntheses, respectively. Physicochemical techniques clearly demonstrate that the triblock surfactant/CTMACl molar ratio has to be carefully controlled in order to i) obtain a significant amount of Mo in the mesoporous silica and ii) retain the SBA-15 structure.
Model of vapor-liquid equilibria for aqueous acid gas-alkanolamine systems using the electrolyte-NRTL equation

Un modele important du point de vue thermodynamique est developpe pour representer les equilibres liquide vapeur dans des systemes ternaires constitues d'un gaz acide, H 2 S ou CO 2 , d'un alcanolamine, monoethanolamine ou diethanolamine et d'eau
Reproducibility in X-ray reflectometry: results from the first world-wide round-robin experiment

X-ray reflectometry (XRR) is a well established technique to evaluate quantitatively electron density, thickness and roughness of thin layers. In this paper, results of the first world-wide XRR round-robin experiment, involving 20 laboratories, are presented and discussed. The round-robin experiment was performed within the framework of the VAMAS Project `X-ray reflectivity measurements for evaluation of thin films and multilayers', the aim of which is to produce a `good practice' manual for XRR. The reproducibility of measurements obtained using different equipment has been investigated. The influence of the fitting of the experimental data was shown to be non-negligible compared with the experimental factors. The dynamic intensity range proves to be an important parameter for obtaining a good quality measurement. A simpler test sample which does not develop a surface oxide layer over time is now the subject of a follow-up study.
A protocol for assessment of uncertainty and strength of emissions data

This method is intended to assist in characterizing uncertainties in emissions data for the Mileubalans and to identify critical issues related to uncertainty. The method assesses both quantitative and qualitative dimensions of uncertainty. Quantitative uncertainties are expressed by assigning probability distributions to the main emissions parameters and propagating those uncertainties via Monte Carlo simulations. Qualitative dimensions of uncertainty are expressed by use of a pedigree method, which provides rankings on a variety of qualitative attributes of emissions parameters. The general features of the method are described below as a series of steps. The first steps attempt to make explicit the structure of the system in which the emissions data is collected by disaggregating the data. A series of steps follow that which are designed to identify the main assumptions employed and key sources of error. These steps help to calibrate the analyst in providing qualitative and quantitative uncertainty estimates in sections 9 and 10. The final sections cover the use of sensitivity analyses and communication of results. Much of the data generated with the method is organized via a Monte Carlo / Pedigree spreadsheet, which is implemented with the '@RISK' software package. Note that the method is designed to provide a fairly rapid overview and diagnosis of uncertainty so that it can be adapated and used as a standard in a range of emissions studies. It should help structure uncertainty analysis on sets of data where this has not yet been done, or provide a convenient form to represent uncertainties where more detailed analysis on uncertainties has already been completed. The method also adds features that are not normally included in conventional uncertainty analyses. It is intended to convey the most salient uncertainties, and to provide guidance on where to put effort to improve the quality of emissions estimates. The method encourages a consistent characterization of uncertainty, avoiding the use of more precision than is justified by available knowledge. Finally, the method does not attempt to be exhaustive in characterizing all possible uncertainties. In particular, it does not provide a lot of focus on 'structural' uncertainties, which are assumed to play a more modest role in the assessment of emissions data than they do in other domains.
The Chemical State of Gallium in Working Alkane Dehydrocyclodimerization Catalysts. In situ Gallium K-Edge X-Ray Absorption Spectroscopy

Ga species in H-ZSM5 zeolites catalyze rate-limiting dehydrogenation steps during the conversion of alkanes to aromatics. Specifically, they promote the recombinative desorption of H-adatoms as H2 and thus inhibit undesired cracking reactions. Here, we describe studies of the physical and chemical state of Ga using in-situ X-ray absorption at the Ga K-edge. Ga+3 species initially present in fresh catalysts reduce at temperatures below 770 K during hydrogen pretreatment or propane reactions. Reduced Ga is present in highly dispersed form without Ga nearest neighbors, probably as a monomeric hydride species coordinated to basic oxygens within zeolite channels. These hydride species are driven to release molecular hydrogen by the high surface hydrogen fugacities that develop during propane dehydrocyclodimerization on H-ZSM5. Reduced Ga species reoxidize to Ga+3 when samples are cooled to room temperature in flowing H2, suggesting that active forms of Ga exist only at reaction conditions. This work illustrates the critical need for in-situ techniques to establish the chemical form of catalytic sites and the misleading conclusions that can arise from the exclusive use of pre- and postreaction characterization to suggest the nature of the catatlytic sites.
Carbon arc plasma doped with Fe and Co/Ni: Spectroscopy and formation of carbon nanostructures

Carbon nanostructures (fullerenes and nanotubes) have been effectively produced using carbon arc technique with homogenous Fe- and Co/Ni-doped anodes. The emission spectroscopy of the arc plasma with evaporated dopants was carried out and temperatures and concentrations of active species were evaluated. The solid products were characterized by MS and SEM techniques.