Miracle-dz/UniFAR-FTUs huggingface dataset:
Enhancement of osmium detection in inductively coupled plasma atomic emission spectrometry

Use of /sup 187/Re as a cosmochronometer has been investigated primarily by Luck et al. As part of a project to develop /sup 187/Re-/sup 187/Os chronometry, it became necessary to develop a method for the determination of nanogram quantities of osmium. The instability of osmium in various chemical environments limited the type of separation and purification chemistry that could be used. Previously reported osmium detection limits obtained in inductively coupled plasma atomic emission spectrometry (ICP-AES) vary from 38 ng/mL to 1 . mu.g/mL (8-10). This variation was generally attributed to the unexplained chemical behavior of osmium. Summerhays et al. observed, when using nebulization, that the signal intensity of osmium increased with time in 9 M HNO/sub 3/. They attributed this rise in intensity to the formation in solution of the volatile species OsO/sub 4/. The signal intensity did not reach a stable value over the period of investigation. The authors decided to take advantage of the volatility of OsO/sub 4/ and to introduce it directly into the plasma torch. A stable, enhanced signal for OsO/sub 4/ was achieved after identifying (1) a stable matrix solution, (2) an efficient oxidant, (3) the ideal temperature for the reaction, and (4) the optimum instrumentalmore » operating parameters. « less
Cobalt Molybdenum Bimetallic Nitride Catalysts for Ammonia Synthesis

Cs promoted cobalt molybdenum bimetallic nitride (Co3Mo3N) synthesized by nitridation of cobalt molybdate hydrate with ammonia at 973K was stable and more active for ammonia synthesis (15 mmol h−1g−1) at 673 K under 3.1 MPa (N2 + 3H2) than a doubly promoted iron catalyst.
The economic implications of carbon cycle uncertainty

This paper examines the implications of uncertainty in the carbon cycle for the cost of stabilizing carbon dioxide concentrations. Using a state of the art integrated assessment model, we find that uncertainty in our understanding of the carbon cycle has significant implications for the costs of a climate stabilization policy, with cost differences denominated in trillions of dollars. Uncertainty in the carbon cycle is equivalent to a change in concentration target of up to 100 ppmv. The impact of carbon cycle uncertainties are smaller than those for climate sensitivity, and broadly comparable to the effect of uncertainty in technology availability
Measurement of molecular weight distributions of organic halide in kraft mill waste streams, waste solids and pulp

Abstract Analytical procedures were developed for determining the apparent molecular weight (AMW) distribution of organic halide in both liquid and solid pulp and paper process components. The techniques included molecular weight separations using ultrafiltration (UF) and determinations using adsorption‐pyrolysis‐microcoulometry (AC/MC). Correction coefficients for rejection properties of UF membranes were determined using a diafiltration technique.
Alignment of Ni- and Co-related centres during the growth of high-pressure high-temperature diamond

An extensive study of Co- and Ni-related centres in high-pressure synthetic diamond, using electron spin resonance, optical absorption and luminescence techniques, has revealed that most of these defects, in samples grown at low temperature (), exhibit preferential alignment, i.e. a non-equal distribution over crystallographically equivalent orientations. Remarkably, this observation applies not only to defects assumed to involve only an Ni or a Co atom, but also to some Ni–N complexes. Annealing at T>1600 °C induces nitrogen mobility and the corresponding formation of numerous Ni–N- and Co–N-related centres. This annealing eventually destroys the preferential polarization of low-temperature centres.
Chitosan‐grafted poly(hydroxyethyl methacrylate‐co‐glycidyl methacrylate) membranes for reversible enzyme immobilization

Epoxy group-containing poly(hydroxyethyl methacrylate/glycidyl methacrylate), p(HEMA/GMA), membrane was prepared by UV initiated photopolymerization. The membrane was grafted with chitosan (CH) and some of them were chelated with Fe(III) ions. The CH grafted, p(HEMA/GMA), and Fe(III) ions incorporated p(HEMA/ GMA)-CH-Fe(III) membranes were used for glucose oxidase (GOD) immobilization via adsorption. The maximum enzyme immobilization capacity of the p(HEMA/GMA)-CH and p(HEMA/GMA)-CH-Fe(III) membranes were 0.89 and 1.36 mg/mL, respectively. The optimal pH value for the immobilized GOD preparations is found to have shifted 0.5 units to more acidic pH 5.0. Optimum temperature for both immobilized preparations was 10°C higher than that of the free enzyme and was significantly broader at higher temperatures. The apparent K m values were found to be 6.9 and 5.8 mM for the adsorbed GOD on p(HEMA/GMA)-CH and p(HEMA/GMA)-CH-Fe(III) membranes, respectively. In addition, all the membranes surfaces were characterized by contact angle measurements.
Square-Wave Anodic Stripping Voltammetry (SWASV) for the Determination of Ecotoxic Metals, Using a Bismuth-Film Electrode

This article reviews the use of square wave anodic stripping voltammetry for the simultaneous determination of ecotoxic metals (Pb, Cd, Cu, and Zn) on a bismuth-film (BiFE) electrode. The BiFE was prepared in situ on a glassy-carbon electrode (GCE) from the 0.1 mol L−1 acetate buffer solution (pH 4.5) containing 200 µg L−1 of bismuth (III). The addition of hydrogen peroxide to the electroanalytical cell proved beneficial for the interference-free determination of Cu (II) together with zinc, lead, and cadmium, using the BiFE. The experimental variables were investigated and optimized with the view to apply this type of voltammetric sensor to real samples containing traces of these metals. The performance characteristics, such as reproducibility, decision limit (CCa), detection capability (CCβ), sensitivity, and accuracy indicated that the method holds promise for trace Cu2+, Pb2+, Cd2+, and Zn2+ levels by employment of Hg-free GCE with SWASV. CCa, and CCβ were calculated according to the Commission Decision of 12 August 2002 (2002/657/EC). Linearity was observed in the range 20–280 µg L−1 for zinc, 10–100 µg L−1 for lead, 10–80 µg L−1 for copper, and 5–50 µg L−1 for cadmium. Using the optimized conditions, the stripping performance of the BiFE was characterized by low limits of detection (LOD). Finally, the method was successfully applied in real as well as in certified reference water samples.
Low electrical percolation threshold and PL quenching in solution-blended MWNT–MEH PPV nanocomposites

Pristine multiwall carbon nanotubes (MWNT) (synthesised using CVD approach) and poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH PPV) based composites were prepared using a solution blending approach by employing various nanotube weight fractions. The prepared composites have been characterised using SEM, AFM, PL spectroscopy, UV-Vis studies and I–V characterisation. Increase in MWNT concentration has been found to quench the PL spectra of the composites suggesting photoinduced electron transfer from polymer to MWNT. The increase in MWNT concentration also increases the absorption of the composites. PL quenching and increase in absorption are desirable attributes for the design of photovoltaic systems. Also, the electrical conductivities of the composites can be described by the scaling law based on percolation theory and based upon the scaling law, a low electrical percolation threshold value (0.5 wt%) has been obtained for this composite system. The value of t (critical exponent) based on percolation theory is found to be 1.11. The low value of t is attributed to the aggregation and bundling of nanotubes in the prepared composites, as is evident from SEM and AFM micrographs. The turn-on voltage is also found to be reduced in the case of polymer–nanotube composite system as compared to the pristine polymer system. Also, it has been observed that at higher weight percentages, the MWNTs form an immensely dense network and act as nanometric heat sinks, thus preventing the build up of large thermal effects, caused by the increased current in the pixels at higher voltages. Analysis of these optical and electrical properties is important before utilising the composite in organic electronics applications, in order to obtain more scientifically correct and repeatable results with fabricated devices.
Modulation of cell adhesion in the immune system through ICAM-1, -2, and -3

The intercellular adhesion molecules (ICAMs) play a prominent role in the regulating migration and activation of both dendritic cells (DC) and T lymphocytes in the immune system. Recent observations demonstrated that both LFA-1 and DC-SIGN, two structurally unrelated adhesion receptors, regulate leukocyte and dendritic cell function by binding of the same ICAMs. Here, we focus on the structure/function relationship between DC-SIGN and LFA-1 to obtain insight in their action that tunes both DC and T cell migration and activation to control immunity.
Isolation and Characterization of Abietic Acid

Abietic acid was isolated by means of isomerization and amination reaction-crystallization coupled with ultrasonic wave. Isomerization rosin and ethanolamine were used as raw materials, 95% ethanol as recrystallization solvent, the effects of reaction temperature, reaction time, agitating velocity, ultrasound intensity and recrystallization times on the purity and yield of abietic acid were investigated. The suitable isolation conditions were obtained as follow: reaction temperature 30 °C, reaction time 40 min, agitating velocity 400 rpm, ultrasound intensity 300 W and freeze crystallization of amine salt three times. The purity and yield of abietic acid were 98.52% and 54.93% when the suitable conditions were used. And it was then characterization by its melting point, specific rotation, UV, FTIR and NMR, all evidence indicated that the purification product was abietic acid.
Water and its relation to broken bond defects in fused silica

We have studied the effects of water and defects on the Raman spectrum of fused silica. Intensities of defect lines at 604 and 490 cm−1 were found to increase with fictive temperature and to decrease with increasing OH content. The results suggest that water in the melt is preferentially trapped at the defect sites. The increased sensitivity obtained by using an optical fiber as the sample enabled us to see for the first time the Si– (OH) stretching vibration at 970 cm−1. The Si–(OH) intensity agrees with that of the 1100 cm−1 dangling oxygen line in a silica fiber weakly doped with K2O. A comparison with other spectral features shows that the Raman cross section for the Si–O stretch is extremely weak. This weak cross section contributes to the weak Raman intensity of the 1100 cm−1 lines in both fused and crystalline SiO2 and also explains why the dangling oxygen stretching vibration is not observed by Raman scattering in neutron damaged silica. Measurements of the much stronger 3690 cm−1 OH stretching vi.
Temporal denitrification patterns in different horizons of two riparian soils

The dynamics of biological denitrification in riparian soil is still poorly understood. We studied the spring‐time pattern of denitrifying enzyme activity (DEA) and the rate of denitrification (DNT) in two hydromorphic riparian soils, one a mollic Gleysol and the other a terric Histosol. The average DEA ranged from 73 to 1232 ng N g−1 hour−1, and DNT ranged from 4 to 36 ng N g−1 hour−1. Both DEA and DNT diminished with increasing depth in both soil types. This decrease corresponded to a decrease in total and K2SO4‐extractable organic carbon and K2SO4‐extractable mineral nitrogen. The DEA and DNT differed in their dynamics. The former had no evident pattern in subsurface horizons but increased with temperature at the end of spring in surface and structural horizons. The DNT diminished as the soil dried in the mollic Gleysol when the water table fell. In the terric Histosol, the water table was still too high at the end of spring to affect the DNT. The results suggest that the vertical pattern of denitrification is related to that of organic carbon content. This organic carbon content determines biological activity and the supply of carbon and nitrous oxides. In biologically active horizons temperature drives the dynamics of DEA, whereas soil moisture drives the dynamics of DNT. Our results show the importance of the dynamic soil–water relationship in controlling denitrification within the riparian zone.
Raman measurement of the grain size for silicon crystallites

Etude par diffusion Raman des echantillons de a-Si:B:H prepares par la methode CVD, en utilisant des temperatures de depot et des niveaux de dopage differents. Interpretation des resultats experimentaux en termes de la mesure de la taille du grain des cristallites de silicium
Amplified microgravimetric gene sensor using Au nanoparticle modified oligonucleotides

A novel microgravimetric gene sensing system has been developed using an oligonucleotide anchored on the gold electrode of a quartz crystal microbalance and an Au nanoparticle modified oligonucleotide, both of which formed a sandwich-type ternary complex with the target DNA to give an amplified frequency response.
Proton dissociation and transfer in a phosphoric acid doped imidazole system

The dynamics and mechanisms of proton exchange in a phosphoric acid (H3PO4) doped imidazole (Im) system were studied using a quantum chemical method at the B3LYP/TZVP level and Born–Oppenheimer molecular dynamics (BOMD) simulations. The theoretical studies began with selecting the appropriate presolvation models for proton dissociation and transfer, which were represented by embedded and terminal hydrogen bond (H-bond) structures of H+(H3PO4)(Im)n(n = 1–4), respectively. B3LYP/TZVP calculations confirmed that excess proton conditions are required to promote proton exchange, and the intermediate complexes are preferentially formed in a low local-dielectric environment. In contrast, a high local-dielectric environment is required to stabilize the positive charge and prevent the proton from returning to the original Im molecule. The static results also revealed that the embedded structure with n = 2 represents the smallest, most active intermediate complex for proton dissociation, whereas the terminal structure with n = 3 favors proton transfer in the Im H-bond chain. BOMD simulations confirmed the static results and further suggested that the fluctuations of the H-bond chain lengths and the local-dielectric environment must be included in the proton dissociation and transfer mechanisms. Analyses of the time evolutions of torsional angles in the Im H-bond chain showed characteristic solvent structure reorganization, regarded as helical-rotational motion, which drives the proton away from the H3PO4 dopant. The current theoretical results showed in detail for the first time the interplay among the “key molecular motions” that fundamentally underlie the dynamics and mechanisms of proton exchange in the H3PO4 doped Im H-bond system.
Calibration Algorithm of Surface Charge Density on Insulating Materials Measured by Pockels Technique

Surface charges greatly affect the discharge/flashover development process across an insulator. The relationship between surface charge distribution on insulating materials and measurement data based on Pockels technique is discussed, and an improved algorithm is built to calculate the real surface charge density from original data. In this algorithm, two-dimensional Fourier transform technique and Wiener filter are employed to reduce the amount of numerical calculation and improve the stability of computation. Moreover, this algorithm considers not only the influence of sample's thickness and permittivity, but also the impact of charges at different positions. The achievement of this calibration algorithm is demonstrated in details. Compared with traditional algorithms, the improved one supplies a better solution in the calibration of surface charge distribution on different samples with different thickness.
Visualising bioprocesses using ‘3D-Windows of Operation’

The operation of bioprocesses involves handling many variables with complex interactions. The visualisation of interactions is vital if suitable conclusions are to be drawn. This paper extends the previously developed ‘Windows of Operation’ to three dimensions, enabling the effects of three parameters to be visualised simultaneously. A tool with a graphical user interface has been developed to enable the generation of ‘3D-Windows of Operation’ and the visualisation of the effects of the variation of any three control variables. Its use is illustrated with simulations of enzyme production. A number of control variables and the effects of the imposition of constraints on the range of possible operating values are investigated. Changes in the range possible are related to the variation in specific constraints or variables. Finally, it is illustrated how these diagrams and operation heuristics may be used to select suitable operating conditions for the bioprocess. Copyright © 2004 Society of Chemical Industry
Comparison of different methods to contact to nanowires

A comparison of four different methods to make electrical contact to both 100nm gold nanowires and 50nm multiwall carbon nanotubes is given. The techniques are compared in terms of the success yield, contact resistance, complexity of the fabrication steps, and potential for creating novel device structures and architectures. The different methods compared are (i) in situ micromanipulation of wires onto prepatterned electrodes, (ii) ion and electron beam assisted deposition, (iii) electron beam lithography, and (iv) drop casting of wires from solution onto prepatterned electrodes.
Hydrodynamic Studies on Zeolite Fluidized Beds

The present study presents systematic experimental data on the fluidization of zeolite particles in water-solid fluidized beds. Four particle size groups, 90-180 ? m, 180-250 ? m, 250-315 ? m and 315-500 ? m and 22 different volumetric flow rates were used, corresponding to Rep of 0.012 to 1.452. All particle sizes showed smooth flow rate vs expanded bed height curves. As is proven, the Ergun equation is useful for determining the minimum fluidization velocity for the large particle sizes by using a fixed sphericity value of 0.354. For the fluidized bed regime (us>umf), the Ergun equation fails to represent the data as it results in fluctuating particle sphericity values, while the RichardsonZaki model seems to correlate the data for the large particle sizes only. A new correlation is presented, connecting bed voidage to Rep for all particle sizes with an average relative error of 2.38±2.49% and the range is 0.02-9%.
Chain Stiffness and Excluded-Volume Effects in Polyelectrolyte Solutions: Characterization of Sodium Poly(2-acrylamido-2-methylpropanesulfonate) in Aqueous Sodium Chloride

Fourteen samples of sodium poly(2-acrylamido-2-methylpropanesulfonate) ranging in weight-average molecular weight from 1.7×103 to 1.4×106 have been studied by static light scattering (or sedimentation equilibrium) and viscometry to characterize the polyelectrolyte in 0.05 and 0.5 M aqueous NaCl at 25 °C. The measured intrinsic viscosities (except for the two lowest molecular weights) and radii of gyration in the respective solvents are consistently described by combinations of the theories for unperturbed wormlike chains and excluded-volume effects (in the quasi-two-parameter scheme) with the parameter sets: q (the total persistence length) = 1.5 nm, ML (the linear mass density) = 900 nm−1, d (the chain diameter) = 1.6 nm, and B (the excluded-volume strength) = 3 nm in 0.5 M aqueous NaCl and q=3.0 nm, ML=900 nm−1, d=1.7 nm, and B=6.2 nm in 0.05 M aqueous NaCl. It is shown that the end effect on the electrostatic persistence length hardly affects the estimation of q in the aqueous salts.
A new general methodology for deriving effective Hamiltonians for atoms and molecules. Application to the transferability of atomic potentials in the hydrocarbon series

A new general methodology for deriving, from first principles, effective Hamiltonians by Fourier techniques is presented. The Fock operator is shown to be a particular one‐electron effective Hamiltonian. Other one‐electron effective Hamiltonians are suggested. The methodology is applied to a first study of the transferability of atomic potentials in the hydrocarbon series.
Exploring the interplay between ligand and topology in zeolitic imidazolate frameworks with computational chemistry

In this paper, we briefly describe recent computational studies related to the exploration and understanding of the complex energy landscape of zeolitic imidazolate frameworks (ZIFs), including zinc-based and lithium boron-based ZIFs. This rich and vast landscape can be usefully navigated with the aid of computational chemistry, by studying existing crystal structures and screening hypothetical structures selected for their potentially interesting topologies. Energy–density trends are discussed, together with the key role of linker–linker interactions.
Large-eddy simulation modeling of turbulent flame synthesis of titania nanoparticles using a bivariate particle description

Flame-based synthesis of nanoparticles is an important chemical process used for the manufacturing of metal oxide particles. In this aerosol process, nanoparticle precursors are injected into a high-temperature flame that causes precursor oxidation, nucleation, and subsequent growth of solid particles through a variety of processes. To aid computational design of the aerosol process, a large-eddy simulation (LES) based computational framework is developed here. A flamelet-based model is used to describe both combustion and precursor oxidation. The solid phase nanoparticle evolution is described using a bivariate number density function (NDF) approach. The high-dimensional NDF transport equation is solved using a novel conditional quadrature method of moments (CQMOM) approach. Particle phase processes such as collision-based aggregation, and temperature-induced sintering are included in this description. This LES framework is used to study an experimental methane/air flame that used titanium tetrachloride to generate titania particles. The simulation results show that the evolution process of titania nanoparticles is largely determined by the competition between particle aggregation and sintering at downstream locations in the reactor. It is shown that the bivariate description improves the prediction of particle size characteristics, although the large uncertainty in inflow and operating conditions prevent a full scale validation. © 2013 American Institute of Chemical Engineers AIChE J 60: 459–472, 2014
Structural and Optical Properties of ZnCoO Thin Film Prepared by Electrodeposition

An oxide diluted magnetic semiconductor, Co doped ZnO thin film was successfully fabricated by cathodic electrodeposition method. X-ray diffraction studies demonstrate that the ZnCoO thin film indicates that the wurtzite structure. X-ray photospectroscopy studies suggested Co ions have a chemical valence of 2+. Optical absorption spectrum further confirmed Co ions have been doped into ZnO crystal lattice successfully with substituting positions of Zn ions. In photoluminescence spectrum, the UV emission band shifted to low energy side because of the doping effect.