Miracle-dz/UniFAR-FTUs huggingface dataset:
An ab initio study of the relative stabilities and equations of state of Fe3S polymorphs

Abstract An investigation of the relative stabilities and equations of state of possible Fe3S polymorphs was conducted using first-principles pseudopotential calculations. These calculations were based on density functional theory and performed using ultrasoft Vanderbilt pseudopotentials within the generalized gradient approximation. In accord with experiment, we found that the tetragonal Fe3P-type polymorph is the only stable phase along the 0 K isotherm as a function of pressure. Fe3S exhibits permanent magnetism at ambient conditions (Fei et al., 2000), but magnetism is suppressed by pressure and temperature, and therefore non-magnetic data are appropriate ones to use for modelling planetaryinteriors. For this reason, and because the Fe3P-type polymorphof Fe3S contains 32 atoms per unit cell it was impractical to incorporate magnetic properties into the simulations of this phase, we studied the behaviour of the non-magnetic phase. We obtained values of 250 GPa for the bulk modulus, K0, and 4.61 for its first derivative withrespect to pressure, K0ʹ, by fitting a 3rd order Birch-Murnaghan equation of state to the calculated internal energy as a function of volume for the non-magnetic Fe3Ptype Fe3S. This suggests that a pressure far greater than that expected in the Martian interior would be needed to achieve a density comparable to that of the Martian core. We therefore conclude that it is unlikely that the core of Mars contains significant amounts of solid Fe3S.
Simple Hamiltonian for quantum simulation of strongly coupled 
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We find a simple spin Hamiltonian to describe physical states of $2+1$ dimensional SU(2) lattice gauge theory on a honeycomb lattice with a truncation of the electric field representation at $j_{\rm max}=\frac{1}{2}$. The simple spin Hamiltonian only contains local products of Pauli matrices, even though Gauss's law has been completely integrated out.
Photochemistry of N2O Essential to a Simplified Vacuum‐Ultraviolet Actinometer

The net number of molecules generated per quantum absorbed (ΦΔn) in the photodecomposition of N2O with 1849‐A light was shown to be 1.00±0.05 in the range 4 to 214 torr N2O at room temperature. Direct measurement of ΦNO at initial pressures of from 5 to 30 torr N2O, and the constancy of ΦΔn over a large N2O pressure range, indicate that ΦNO probably does not change with N2O pressure under the above conditions. In most other respects, our results agree with those of other workers. It is shown that ΦΔn should be 1.00±0.05 in the range 1380–2100 A, and that ΦΔn should be ∼0.8 in the range 1200–1380 A.
Slurry sampling and fluorination–electrothermal vaporization inductively coupled plasma atomic emission spectrometry for the direct determination of molybdenum in food

A method for the direct determination of Mo in various types of food by fluorination–electrothermal vaporization inductively coupled plasma atomic emission spectrometry has been developed and optimized. Slurry samples were prepared by ultrasonic wave vibration, after pre-treatment and direct injection into the graphite furnace using polytetrafluoroethylene as a fluorinating agent. The procedure was applied to the determination of Mo in National Institute of Standards and Technology Standard Reference Materials 1567 Wheat Flour, 1568 Rice Flour and 1577 Bovine Liver. The values found were in reasonable agreement with the certified values, with a detection limit of 0.7 ng ml–1 and an RSD of 3.2%(n= 10) at a concentration of 0.1 µg ml–1. The proposed procedure has been applied successfully to the analysis of various types of food samples; the recovery ranged between 92 and 105%.
Modeling of direct current micro-plasma discharges in atmospheric pressure hydrogen

Numerical simulations and experimental studies were conducted to characterize direct current (dc) hydrogen discharge for a pin plate electrode configuration having an inter-electrode separation distance of 400 µm. A self-consistent two-dimensional hybrid model was developed to simulate the atmospheric pressure dc hydrogen micro-discharges. The discharge simulation model considered consists of momentum and energy conservation equations for a multi-component gas mixture, conservation equations for each component of the mixture (electrons, ions, excited species and neutrals) and state relations. The model uses a drift–diffusion approximation for the electron and the ion fluxes. The species considered include H, H2, H+, , , , H2 v=1 and the electrons. The electric field is obtained from the solution of Poisson's equation. Numerical simulations and experimental measurements indicated some of the key features of a normal glow discharge: flat voltage–current characteristics and constant cathode current density. Basic plasma properties such as electron number density, gas temperature, electric field and electron temperature were studied. The model predicted a constant current density of ∼22 A cm−2 in the normal glow regime. The normal current density was found to be a temperature scaled value of a low pressure normal current density. The ion Joule heating and Frank–Condon heating were found to be the dominant gas heating mechanisms. The peak gas temperature of ∼500 K indicated the discharge to be a non-thermal non-equilibrium discharge. Predictions from the model compares favorably well with the experimental measurements.
Isothermal Titration Calorimetry Studies of Binding Interactions between Polyethylene Glycol and Ionic Surfactants

The binding behaviors between poly(ethylene glycol) (PEG) and sodium dodecyl sulfate (SDS) were examined by isothermal titration calorimetry (ITC) technique. The binding interactions between PEG and SDS are dependent on the molecular weights of PEG. At low molecular weight (MW < 400 Daltons), SDS does not bind to PEG chains. As PEG molecular weight increases from 900 to 1450 Daltons, an endothermic peak, which is attributed to the formation of SDS/PEG aggregation complex by the polymer-induced surfactant micellization process is observed. SDS micelles of lower aggregation number adsorb on the PEG backbones and the PEG segments are solubilized in the hydrophobic core of SDS micelles. When the molecular weight exceeds 3350 Daltons, an endothermic peak followed by an exothermic peak is observed. The exothermic curve is associated with the re-hydration of PEG segments from the SDS micellar core to form SDS/PEG aggregation complexes through ion−dipole association, where the re-hydrated PEG backbones are bound .
Micro-scale heterogeneity in water temperature

Micro-scale heterogeneity in water temperature was examined in 6 upland sites in the Western Cape, South Africa. Hourly water temperature data converted to daily data showed that greatest differences were apparent in daily maximum temperatures between shallow- and deep-water biotopes during the warmest period of the year. Pool depth affected water temperature with deeper pools creating a more stable thermal environment. Groundwater-dependency affected water temperature differences with less groundwater-dependent rivers exhibiting greater differences in daily maximum temperatures. The importance of maintaining instream and riparian habitat, including pools, undercut banks, marginal vegetation, and an intact hyporheos, is discussed, giving examples of organisms utilising such habitats as thermal refugia. Considerations when choosing an appropriate model to simulate water temperatures, including groundwater-dependency, temporal and spatial scale, and study objectives, are discussed. Keywords: water temperature, riverine ecosystems, rivers, thermal regimes, biotic responses, aquatic organisms, micro-scale heterogeneity, modelling
Schottky barrier height enhancement on n‐In0.53Ga0.47As

Schottky barrier height enhancement on n‐InGaAs is studied on structures with thin surface layers of different compositions. Counter‐doped p+‐InGaAs layers, as well as layers of n‐ and p‐InP, n‐GaAs, and n‐InGaP of different thicknesses and dopant densities, respectively, were used to enhance the barrier. Titanium was used as a barrier metal to prepare Schottky diodes of different areas and the barrier height is analyzed by current‐voltage measurements. It is observed that the barrier height enhancement by p+‐InGaAs layers increases with the layer thickness and dopant density, respectively, and effective barrier heights up to 0.63–0.68 eV, i.e., higher values than previously reported, have been measured. The barrier height enhancement by counter‐doped p+‐InGaAs layers on n‐InGaAs can be described by the two‐carrier model. Schottky diodes with extremely low reverse current densities have been prepared, JR(1 V) =4.5×10−6 A/cm2. It is shown that lattice‐matched InP surface layers can be used as an alternativ.
Raising the fuel heating value and recovering exhaust heat by on-board oxidative reforming of bioethanol

Several reactions can contribute to the overall process of exhaust gas reforming, during which some of the engine fuel is catalytically converted mainly to H2 and CO. If the predominant reactions are endothermic, the process acts as a means of exhaust-heat recovery, and the fuel heating value is raised. When using conventional gasoline or diesel fuel, the reforming catalyst is required to promote steam- and dry-reforming, at the expense of the exothermic reactions—water gas shift, methanation, partial oxidation and combustion. In this study we show that a precious metal formulation is capable of catalysing most of the key reforming routes with the exception of the water gas shift reaction, under the set of conditions that we have used to simulate an exhaust from a bioethanol-fuelled spark ignition engine. Our results predict that the overall process of exhaust gas reforming of C2H5OH will be oxidative, and yet waste heat will be consumed. The expected increase in fuel heating value is 6%, but can rise towards 20% if there is less O2 available in the exhaust, allowing more of the bioethanol to react by steam- and dry-reforming in the catalyst bed. By feeding the reformate back to the engine, the intention is to improve the fuel economy and emission quality.
A Field Comparison of 'Total Suspended Particles' and PM10'Air Samplers in Collecting Polycyclic Aromatic Hydrocarbons

Abstract Air concentrations of particulate-phase polycyclic aromatic hydrocarbons (PAHs), collected by three samplers, were compared. Tested instruments were two hi-vol samplers-the one for 'total suspended particles' (TSP) and the other provided with a 10-μm cutoff (PM10) inlet-and a lo-vol portable TSP sampler. Sampling was performed under a variety of ambient conditions, at an urban site where vehicle emissions are the prevailing PAH source. Individual concentrations of PAHs were quantified by high-resolution gas chromatography and ranged 0.05 to 6 ng/m3. The PM10 sampler provided concentrations which were on average 73% to 93% (about 90% for the 5- and 6-ring carcinogenic PAHs) of those provided by the hi-vol TSP sampler; the between-instrument ratios showed a good homogeneity throughout the study. The hi-vol and lo-vol TSP samplers, operating at the same face velocity, showed a very good agreement regarding PAH collection (overall mean ratio lo-vol/hi-vol: 97%), but the observed detection limit in lo.
Quantitative sample injection for capillary electrophoresis

An apparatus including a rotary-type injector was designed for quantitative sample injection in capillary electrophoresis (CE), in which both pressurized flow and electroosmotic flow were used to drive the background electrolyte solution. A relative standard deviation of peak area of lower than 1% was achieved by using this apparatus. The effects of back-pressure regulator, restrictor, and applied voltage on separation efficiency and resolution were investigated. The utility of this apparatus in both micro-HPLC and pressurized capillary electrochromatography (pCEC) was also demonstrated.
Daily, Seasonal, and Spatial Trends in PM2.5 Mass and Composition in Southeast Texas Special Issue of Aerosol Science and Technology on Findings from the Fine Particulate Matter Supersites Program

Daily, seasonal, and spatial trends in fine particulate matter concentrations, compositions, and size distributions were examined using data collected through the regulatory fine particulate matter monitoring network in Southeast Texas and during the Gulf Coast Aerosol Research and Characterization Study (GC-ARCH or Houston Supersite). PM2.5 mass concentrations and compositions are generally spatially homogeneous throughout Southeast Texas when averaged over annual or seasonal time periods. There is relatively little seasonality to mean total PM2.5 mass and mean PM2.5 composition throughout the region, although slightly higher concentrations of total mass tend to occur in the spring and late fall. High FRM PM2.5 mass (>20 μg/m3) occurs both when there is high spatial variability among sites and low spatial variability among sites. This suggests that both local and regional emission sources contribute to PM2.5 in Southeast Texas. Sulfate ion (32%), organic carbon (30%), and ammonium ion (9%) are the largest components on average of PM2.5 by mass. Mean diurnal patterns for PM2.5 mass concentrations throughout the region show a consistent morning peak and a weaker and slightly less consistent peak in the late afternoon to early evening. High hourly averaged PM2.5 mass concentrations (>40 μg/m3) tend to be associated with daily average PM2.5 above the annual NAAQS of 15 μg/m3. These high hourly PM2.5 concentrations also tend to occur on days with high diurnal variation, indicative of elevated, short-lived PM2.5 events. In contrast to mass concentrations, particle size distributions are not spatially homogeneous throughout Southeast Texas. Industrial sites have higher concentrations of freshly emitted, primary particles than more residential sites. Because the freshly emitted particles generally have diameters of 0.1 μm or less, these primary emissions do not have as large an impact on PM2.5 mass or bulk composition as they have on the number density of fine particles.
Organization of Functionalized Gold Nanoparticles by Controlled Protein Interactions

Gold colloidal particles were synthesized and modified by molecular self‐assembly. In addition, the reaction of biotinylated colloids with a tetrameric protein, avidin, was studied by optical absorption spectroscopy and dynamic light scattering. The modification involves the chemisorption of octadecanethiol on the gold, with the further attachment of alkyl biotin and cross‐linking with avidin molecules. The specific interaction of avidin with biotin leads to the controlled cross‐linking of particles. The degree of flocculation was quantified using a semi‐empirical flocculation parameter and its dependence on the biotinylation system was studied. The measured data were in good agreement, showing the possibility of regulating the aggregation rate and size of the aggregates using the experimental time, degree of biotinylation, and avidin concentration. The morphology of the self‐assembled gold monolayers, from the aggregated particles, was imaged by high‐resolution scanning electron microscopy. The structure of the thin particulate film depends on the bulk aggregate size and aggregation rate.
Anaerobic microbial activities of a Nigerian onshore oil production facility that uses underground water with zero sulfate concentration for injection.

Aim: To evaluate the anaerobic microbial activities and souring potential of a Nigerian onshore oil production facility that uses zero sulfate underground water for injection. Methodology: Key functional group activities such as the ability to reduce sulfate and generate sulfide by sulfate reducing bacteria (SRB), the ability to reduce nitrate to nitrite by the heterotrophic nitrate reducing bacteria (hNRB) and the ability to reduce nitrate and oxidize sulfide by sulfide oxidizing, nitrate reducing bacteria (so - NRB) were determined in samples using CSB - K medium. Results: Lactate utilizing SRBs and hNRBs were found to be common in most oil field samples while the activities of so - NRBs were limited to very few sam ples. It was also observed that the underground water with zero sulfate concentration and negligible microbial activity poses no souring risk to the oil field under investigation. The produced water and oil samples from the facility though with considerabl e populations and activities of SRBs also recorded negligible concentration of sulfate and some organic nutrients and therefore are not likely to pose some souring risks to the oil facility under investigation. Conclusion: From our investigation, it is evident that the zero sulfate underground water with negligible SRB populations and activities poses no souring risks to the facility under investigation
Elastin as a random‐network elastomer: A mechanical and optical analysis of single elastin fibers

The physical properties of single, 5–8‐μm diameter, water‐swollen elastin fibers have been investigated on a microtest apparatus attached to a polarizing microscope. Analysis of the mechanical and optical properties at extensions below 100% indicate that the elastic modulus (G) has a value of 4.1 × 105 N m−2, the average molecular weight of chains between crosslinks is in the range of 6000–7100, and the stress optical coefficient (C′) is 1 × 10−9 m2 N−1 at 24°C. Analysis of the temperature dependence of the stress optical coefficient indicates that the polarizability of the random link decreases with increasing temperature, with an apparent activation energy for this process of the order of 1.6 kcal/mol. Analysis of the non‐Gaussian mechanical and optical properties at extensions above about 100% suggest that the chains between crosslinks contain approximately 10 “effective” random links, with each link consisting of 7–8 amino acid residues. These parameters for the random chains in the elastin network have been used to predict the dimensions of other random proteins. The close correlation of these predictions with published values for the dimensions of a series of proteins in solution in 6M guanidinium hydrochloride provides an independent test of the appropriateness of our analysis.
State of the Art in Miniaturized Separation Techniques

Miniaturized separation techniques have become very attractive recently because they offer a number of advantages over classic ones, for example, reduced chemicals consumption, separation improvement, and better sensitivity. It is also very important that they require minute samples, which is very often of primary importance in the environmental or biomedical sciences. In general, miniaturized systems that are being developed currently are divided into column and chip ones. For best performance of the separation microsystem, it must be properly designed in the terms of volumes and shapes of the parts it consists of. Theoretical considerations present this problem. As column systems are better known and understood the microcolumns are more frequently developed. Current works are focused on the preparation of unified columns that can be used in various techniques — for example, in micro-HPLC and CEC. Because of problems occurring in packed capillary column preparation and utilization, monolithic (rod) columns are developed to overcome the problems of inhomogeneity of packing or bubble formation under electroosmotic flow conditions. The requirements of minute sample analysis have been resolved by the construction of chip devices originating from total analysis system (TAS). Such systems are primarily designed for zone electrophoresis separations; however, micellar electrokinetic chromatography, gel chromatography, electrochromatography, or liquid chromatography can be performed using a chip device. In this article the most important trends in miniaturization of the separation systems are discussed, including theory, system preparation, and performance as well as exemplary applications.
Applications of Amperometric Silica Sol-Gel Modified Enzyme Biosensors

ABSTRACT The applications of amperometric sol-gel modified enzyme biosensors in numerous analyses of clinical, industrial and environmental importance have been demonstrated. Certain biosensors have been employed as the sensor in a FIA amperometric detector. The results obtained by the biosensors generally corroborate well with the classical or official method. In many cases, the recovery results obtained by the biosensor have been satisfactory.
AN EFFECTIVE NUMERICAL SOLUTION OF GUIDED WAVES EQUATIONS

Many p rob lems of waves p r o p a g a t i o n s u c h as underwa te r sound p r o p a g a t i o n , . l o n g r a n g e r a d i o waves p r o p a g a t i o n , mar ine se i smology , l i g h t f i b e r p r o p a g a t i o n are of i n t e r e s t i n c a s e n o t o n l y of l a y e r e d media , b u t of media w i t h p r o p e r t i e s v a r y i n g i n two d i r e c t i o n s . Among t h e ma themat i ca l p r o c e d u r e s t o p r e d i c t waves f i e l d s i n s u c h c i r c u m s t a n c e s t h e most used are t h e method of c o u p l e d modes / 1 , 2 / and t h e p a r a b o l i c e q u a t i o n t e c h n i q u e i n its man i fo ld r e a l i z a t i o n s /3,4/. In t h e r e l a t i o n f o l l o w i n g t h e e q u i v a l e n c e of coup led modes o r gu ided waves e q u a t i o n s t o t h e a p p r o p r i a t e a b s t r a c t p a r a b o l i c e q u a t i o n is e s t a b l i s h e d and t h e a l g o r i t h m t o s o l v e t h e s i m p l i f i e d form of t h e l a s t is proposed , f e a t u r i n g t h e low computa t ion c o s t a t t h e any g i v e n accuracy . 11. GUIDED WAVES EQUATIONS OPERATOR FORM. A s a model of a c o u s t i c a l waves p r o p a g a t i o n p r o c e s s we s h a l l u s e t h e s y s t e m of p b e i n g a c o u s t i c a l p r e s s u r e , v ,v a c o ~ t s t i c a l v e l o c i t y c a r t e s i a n components, f s , f 2 x z d i f f e r e n t i a l e q u a t i o n s of t y p e c a r t e s i a n components of e x t e r n a l f o r c e s d e n s i t y , V-external volume v e l o c i t y d e n s i t y , a l l of them b e i n g f u n c t i o n s of c a r t e s i a n h o r i z o n t a l c o o r d i n a t e x o r r a n g e and z = f Dx 0 imp D iwp 0 2-1 -2 imp C Dz +x
Application of polypyrrole to flexible substrates

Conducting polymers such as polypyrrole may be useful in smart packaging products, provided application methods can be developed that circumvent the insolubility and infusibility of these materials. Experiments were conducted in five research areas relevant to the application of polypyrrole to nonrigid substrates. The studies reveal that application of polypyrrole from the liquid phase, either by deposition from depleted bulk solution or inkjet printing dispersions, is unlikely to give films as regular as those produced by vapor phase polymerization. Using the latter approach, two potential methods of applying patterned polypyrrole films to nonrigid substrates were developed. The first used hypochlorite to pattern a continuous film of polypyrrole, previously applied by vapor phase polymerization. The second used inkjet printing to apply an oxidant solution, whose pH had been raised with a volatile base, to nonrigid substrates. The higher pH reduced corrosion of the print head, increasing the lifetime of printers exposed to oxidative compounds. The base was subsequently evaporated by heating, and the dried oxidant used as a template for vapor phase polymerization of polypyrrole. This method gave smooth, shiny and adherent polypyrrole films on papers and polyester transparency, with high resolution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3938–3947, 2007