Miracle-dz/UniFAR-FTUs huggingface dataset:
Turbulent dispersion coefficients in cyclone flow: An empirical approach

Among the various theories available to predict cyclone collection efficiency, the finite diffusivity theory of Mothes and Loffler (1988) has been shown to give the best fit of the observed grade-efficiency curves. However, lack of knowledge on the dependence of the particles' turbulent dispersion coefficient with cyclone geometry, operating conditions and particle size has so far hindered the application of this theory for predictive purposes and for improved cyclone design. In this work, this theory is applied for predictive purposes, through the use of an empirical relation for the particles turbulent dispersion coefficient. The proposed relation is based on an analogy with turbulent dispersion in packed beds, and correlates the particle radial Peclet and Reynolds numbers. Laboratory-scale reverse-flow cyclones of previously unpublished geometries were built to test the applicability of the proposed relation. The Mothes and Loffler (1988) theory, when coupled with the proposed estimates of turbulent dispersion coefficients, is a powerful tool for predicting cyclone collection efficiency, short of using computational fluid dynamics tools. Parmi les differentes theories existantes pour predire I'efficacite de collection des cyclones, on motnre que la theorie de diffusivite de Mothes et Loffler (1988) donne le meilleur calage des courbes d'efficacite des grades obsereves. Toutefois, le manque de connaissances sur la dependance du coefficient de dispersion turbulente des particules en fonction de la geometrie du cyclone, des conditions de fonctionnement et de la taille des particules a empeche jusqu'a present I'application de cette theorie a des fins de prediction ou d'amelioration de la conception des cyclones. Dans ce travail, on applique cette theorie a des fins de prediction, en recourant a une relation empirique pour le coefficient de dispersion turbulente des particules. La relation proposee s'appuie sur une analogie avec la dispersion turbulente en lits garnis et s'exprime sous forme d'une correlation faisant intervenir les nombres de Peclet et de Reynolds, radiaux de particules. Des cyclones a ecoulement inverse a I'echelle de laboratoire ayant des geometries non encore publiees ont ete construits afin de tester I'applicabilite de la relation proposee. La theorie de Mothes et Loffler (1 988), lorsqu'elle est couplee aux estimations de coefficients de dispersion turbulente proposees, est un outil puissant pouyr predire I'efficacite de collection des cyclones, sauf si on recourt a des outils de simulation de la dynamique des fluides.
ERROR ANALYSIS IN ESTIMATING SOIL WATER CONTENT FROM NEUTRON PROBE MEASUREMENTS: 1. LOCAL STANDPOINT

We present a variance analysis for quantifying the different sources of errors induced on volumetric water content measurements and calculation of soil water storage with the use of a neutron moisture meter in one single access tube. For comparative purposes, we apply the analysis to field data obtained with two different probes. In each case the calibration curve is established by measuring simultaneously and independently neutron count rates and corresponding water contents. Two different approaches are considered, i.e. the unbiased treatment and the biased treatment. The unbiased treatment differs from the biased by its correction for measurement errors using the leastsquare technique. For the site under consideration, we show that the calibration component is the major contribution to the total variance associated with an individual water content estimation. The use of the unbiased statistical treatment notably decreases the total variance. In cases where the calibration curve is established very accurately, the instrument component can be reduced by increasing the number of count replications at each sampling point or the counting time or both. The loss of precision due to using neutron count rate ratios instead of simple count rates is negligible if several count replications are made in a standard medium or if the counting time is long enough. We show that the rule of integration of water content profiles in order to calculate water storage has a great importance: the use of Simpson's rule drastically decreases the associated variance as compared with the classical trapezoidal method.
Pressure swing adsorption. Part III: Numerical simulation of a kinetically controlled bulk gas separation

Simulation numerique d'un simple systeme a deux lits, dans lequel les effets cinetiques et les changements de debit dus a l'adsorption sont importants. Resolution des equations du modele par la methode de double collocation. Application a la separation d'air sur un tamis moleculaire de carbone (les parametres cinetiques et d'equilibre ayant ete mesures independemment), montrant que l'efficacite predite est en accord avec les donnees d'une unite commerciale dont on dispose
Ion- and electron-assisted gas-surface chemistry—An important effect in plasma etching

The extent to which gas‐surface chemical reactions can be enhanced by energetic radiation (primarily ions and electrons) incident on the surface is described. Emphasis is placed on chemical systems which lead to volatile reaction products. In particular, the reactions of Si, SiO2, and Si3N4 with XeF2, F2, and Cl2 are examined experimentally. Possible mechanisms for the radiation‐induced enhancement are discussed and some technological implications of this process in plasma etching technology and lithography are considered.
On the formation and annihilation of the singlet molecular metastables in an oxygen discharge

We describe a volume averaged global model for an inductively coupled RF oxygen discharge that considers an extensive reaction set that includes the species: O2(X3Σg− ? >), O2(a1Δg ? >), O2(b1Σg+ ? >), O2(A3Σu+ ? >, A’3Δu ? >, c1Σu− ? >), O2+ ? >, O2− ? >, O(3P), O(1D), O+, O−, O3, O3+ ? >, O3− ? >, and electrons. We propose revised rate coefficients for some of the reactions and explore the densities of various species as a function of discharge pressure, in the pressure range 1–100 mTorr. We find that the O2(a1Δg ? >) density can be lower than the O2(b1Σg+ ? >) density in the pressure range from 2.5 to 80 mTorr. The relative reaction rates for formation and annihilation of O2(a1Δg ? >) and O2(b1Σg+ ? >) are evaluated and the most important reactions are indicated. The O− loss process is also studied. The results show that O2(a1Δg ? >) has only a small contribution to the loss of the negative ion O−, while electron impact detachment is a very effective loss process at low pressure (<2 mTorr) and detachment by the oxygen atom O(3P) and the metastable singlet O2(b1Σg+ ? >) are the most effective loss process up to roughly 50 mTorr where charge exchange becomes the most effective process for O− loss.
Internal Loads of Nutrients in Lake Chaohu of China: Implications for lake Eutrophication

This study investigated the impact of internal nitrogen and phosphorus loading on water qualityof Lake Chaohu, China. Results showed that the overall mean concentration of TN and TP in lake water was1.09±0.84 and 0.15±0.84 (SD) mg/L, respectively, indicating Lake Chaohu was highly eutrophic during thestudy period. Mean benthic flux of NH4 +, NO3 -, and PO4 3- were 3.56±1.52 mg N/m2/d, -0.14±0.40 mg N/m2/ d, and -1.54±21.94 μg P/m2/d in summer and were 3.16±1.83 mg N/m2/d, -0.03±0.30 mg N/m2/d, and - 0.11±2.58 μg P/m2/d in fall, respectively. In this study, lake sediments acted as both a source of NH4+ and a sink of PO4 3-. A scenario was used to understand the role of sediments on lake water quality. Results showed that Lake Chaohu would be eutrophic within a month under the impact of internal NH4+ loading when water was diverted to the lake. This indicates that an integrated project combining both a diversion project and dredging of sediments would be necessary for future lake restoration.
Cellulose Acetate and Polyetherimide Blend Ultrafiltration Membranes, I: Preparation, Characterization, and Application

Ultrafiltration (UF) techniques have particular advantages for simultaneous purification, concentration, and fractionation of macromolecules. In this study, polymeric blend ultrafiltration membranes based on cellulose acetate and polyetherimide were prepared by phase inversion technique and characterized in terms of compaction time, pure water flux (PWF), water content, membrane hydraulic resistance, and scanning electron microscopy (SEM). The blend membranes prepared were subjected to the separation of macromolecular proteins such as bovine serum albumin (BSA), egg albumin (EA), pepsin, and trypsin. The molecular weight cut-off (MWCO) of blend membranes obtained from the protein separation studies is also presented. Toxic heavy metal ions such as copper, nickel, zinc, and cadmium were subjected to separation by the blend membranes by complexing them with the polymeric ligand polyethyleneimine. The separation and permeate flux efficiencies of the blend membranes are compared with those of pure cellulose acetate membranes.
Lanthanide Field Tracers Demonstrate Enhanced Transport of Transuranic Radionuclides by Natural Organic Matter

Transuranic (TRU) radionuclides buried 25 years ago in shallow unlined disposal trenches in a fractured shale saprolite had been detected in groundwater from downgradient monitoring wells and in surface water seeps. Field observations had suggested the actinide radionuclides were mobilized by natural organic matter (NOM) and rapidly transported with little retardation. A 73-day natural gradient tracer experiment injected trivalent lanthanides (Nd and Eu) as analogues to determine the mechanisms and rates of actinide transport at the field scale. Adsorption isotherms for 241Am and Eu with saprolite from the site confirmed a very high affinity for adsorption (R > 50 000) in the absence of NOM. However, reactive and nonreactive tracers arrived at approximately the same time along a 10-m long deep flow path, and anion-exchange chromatog raphy and filtration suggested that the mobile lanthanides in groundwater were a NOM complex. Although flow through a shallow flow path was intermittent, reflecting transient .
Nucleation and crystal growth of zeolite A synthesised from hydrogels of different density

Various factors affect the process of zeolite formation and thus the characteristics of the ultimate material. The present study is devoted to the influence of the density of the starting aluminosilicate hydrogels, i.e. the amount of the solid phase in the system, on the characteristics of the final product. Different density (viscosity) of the five alumosiliate gels was obtained by changing the ratio SiO2/H2O, while the ratios Na2O/H2O and SiO2/Al2O3 remained constant. The freshly prepared hydrogels were hydrothermally treated at 80 °C under static conditions. The reaction course was followed by a set of complementary analyses including XRD, chemical analysis, microscopy and thermogravimetry. The linear rate of crystal growth was calculated according to Zhdanov and Samulevich's method. The crystal size distribution curves of the end products were measured and the corresponding curves of nuclei distribution within gel matrix and specific number of crystals were calculated. The observed effect of “local ordered structure” (potential nuclei) formation was commented on from the viewpoint of the autocatalytic nucleation theory.
Preparation and Application of Novel Microspheres Possessing Autofluorescent Properties

Fluorescent microspheres are widely used as biological tracers. In this study, uniformly sized chitosan microspheres crosslinked with glutaraldehyde (CG microspheres) and formaldehyde (CF microspheres) are successfully prepared by the Shirasu Porous Glass (SPG) membrane emulsification technique. Selectively reduced CG microspheres (SRCG microspheres) are obtained by NaBH4 reduction. These chitosan microspheres are found to exhibit fluorescent properties without conjugation to any fluorescent agent. The fluorescence color varies with different crosslinkers and can be modulated by further chemical reduction, whereas the fluorescence intensity can be controlled by tuning the particle size and degree of crosslinking. The autofluorescence of the microspheres is applied to study the phagocytosis of HepG2 cells using the microspheres as novel tracers. Quantitative and qualitative evaluations show that these chitosan microspheres serve as bright, inert, durable, and extremely photostable tracers.
Growth and cadmium accumulation in two durum wheat cultivars

Abstract A solution culture study was conducted to determine the effects of cadmium (Cd) application on Cd accumulation and growth of two durum wheat (Triticum turgidum L. var durum) cultivars. Arcola and DT618 were grown in nutrient solution for 13 days. Cadmium application to nutrient solution significantly (P ≤ 0.05) decreased root and shoot biomass, leaf area, leaf mass, total root length, and chlorophyll a and b concentration of the first leaf. The deleterious effects of Cd on plant growth were explained by a modified version of Weibull distribution function of the form, y = a.exp(b.√Cd), where ‘y’ is the growth parameter, ‘a’ is plant growth in the absence of Cd, and ‘b’ is reduction in growth with per unit increase in solution Cd. Total root length was decreased the most (80%) and chlorophyll b concentration of the first leaf decreased the least (9%) with per unit increase in solution Cd. Although the two cultivars were significantly different in some growth characteristics, both responded similarl.
Changes in Sulfur Content and Isotopic Ratios of Sulfur during Petroleum Maturation--Study of Big Horn Basin Paleozoic Oils

Changes in sulfur content and sulfur-isotope ratios with "thermal maturation" have been studied using Big Horn basin (Wyoming) Paleozoic oils as examples of "single source" oils which have attained different stages of maturity as a result of variations in thermal history. With increasing maturity, API°, GOR, S/N, ^dgrC13, and ^dgrS34 all increase, whereas percentage S and percentage N decrease. Except for the increase in ^dgrS34 and S/N, these changes generally are recognized as typical of the thermal-maturation process. Hydrogen sulfide produced in low concentrations by microbial sulfate reduction in shallow reservoirs varies in ^dgrS34 and generally does not appear to change ^dgrS34 of associated oil. Isotopically unrelated H2S and organic sulfur may remain for long times because of negligible reaction between H2S and oil at low temperatures and low H2S pressures. The major new conclusion from this study is that thermal maturation in high-temperature reservoirs (more than 80-120°C) with sulfate present may involve nonmicrobial sulfate reduction with a negligible isotopic fractionation, producing reduced sulfur species with nearly the same isotopic composition as the reservoir sulfate. In this case, sulfurization and desulfurization of oil compete in kinetically controlled processes resulting in isotopic exchange. The ^dgrS34 of H2S and organic sulfur in oils change toward that of reservoir sulfate. Exchange is faster for H2S than for oil. Initial oils with a homogeneous ^dgrS34 distribution with boiling point and compound type become heterogeneous; the lower boiling fractions approach reservoir s lfate values faster than high-boiling fractions. The large increase in S/N ratio with maturation is attributed to percent S being maintained at a significant level by competing sulfurization and desulfurization processes, whereas percent N continues to decrease. The mechanism for high-temperature sulfate reduction is proposed to be the reaction of H2S and SO4= to produce elemental sulfur and polysulfides, which react rapidly to oxidize and dehydrogenate organic compounds and distribute the sulfur between oil and H2S. High concentrations of H2S may accumulate in this case, and oils or condensates may develop abnormally high concentrations of thiols. H2S is a catalyst as well as a product of the reaction; the process, therefore, may be autocatalytic.
Nitrogen Mineralization in Soil Amended with Crop Residue: An Incubation Experiment Under Flooding Conditions

Incubation studies were carried out to investigate the release of nitrogen in soils. The domestic sewage and soil were analyzed for their physical, chemical characteristics in view of evaluating their suitability for irrigation to agricultural lands in a laboratory experiment. The effluents were added to a soil and incubated at 30±1 0C microbial population, NH4
Simultaneous incorporation of Cr, Zn, Cd, and Pb in the goethite structure

In order to improve our understanding of how the goethite crystal structure is affected by the incorporation of metals (and by variations in the amount of the incorporation), and to review any possible synergistic and antagonistic effects of co-metals, the present investigation focused on the incorporation of multiple (di-, tri-, and tetra-) metals, i.e. Cr, Zn, Cd, and Pb, in the goethite crystallographic structure. A series of single- and multi-metal M-Cr/Zn/Cd/Pb-substituted goethites with M/(M+Fe) molar ratios = 0.10 were prepared. The general sequence of metal entry in single-metal substituted goethites was Zn = Cr > Cd > Pb and in multi-metal-substituted goethites was Zn > Cr ⩾ Cd > Pb. Simultaneous incorporation of Cr, Zn, Cd, and Pb up to 10.5 mole % was achieved in goethite. Synchrotron X-ray diffraction and extended X-ray absorption fine structure (EXAFS) techniques were employed to assess the structural characteristics of the synthesis products. Rietveld refinement of XRD data showed small changes in unit-cell parameters and Fe/M-Fe/M distances due to M substitution(s). A typical goethite-like crystalline structure remained intact, however. The unit-cell parameters were mutually, linearly correlated, though Fe/M-Fe/M distances were not, indicating that complex changes occurred at the local scale. In single-metal substituted goethites, incorporation of Cr reduced the unit-cell volume by 0.13% while that of Zn, Cd, and Pb increased it by 1.09, 3.58, and 0.56%, respectively. The changes in multi-metal-substituted goethites appeared to be the complex combination of that of the individually incorporated metals. The X-ray absorption near edge structure study of Pb-substituted goethites showed that the majority of associated Pb was Pb2+, while Pb4+ was preferred over Pb2+ in the bulk structure. Measurements by EXAFS at the Fe K-edge indicated that the Fe polyhedra contracted in the presence of Cd2+ and Pb2+, providing room for the substitution of larger cations. Measurements by EXAFS at the Cr and Cd K-edges indicated symmetric Cr/Cd polyhedra with single Cr/Cd-O distances and, at Fe and Zn K-edges and the Pb LIII-edge, indicated asymmetric polyhedra with two sets of Fe/Zn/Pb-O distances. The Zn octahedra were possibly Zn(OH)4O2, which enlarged the metal-metal corner-sharing distance to 3.86 Å. This configuration of ligands around the Zn2+ cation might occur to balance local charges. Symmetric polyhedra appeared to reduce steric strains in the structure, compared to the asymmetric polyhedra. The result was that Cr enhanced the incorporation of Zn, Cd, and Pb, while the converse was true for Zn.
Polymer/Layered Silicate Nanocomposites

Polymers filled with low amounts of layered silicate dispersed at nanoscale level are most promising materials characterized by a combination of chemical, physical and mechanical properties that cannot be obtained with macro- or microscopic dispersions of inorganic fillers. Polymer layered silicate nanocomposites can be obtained by insertion of polymer molecules in the galleries between the layers of phyllosilicate. Here, hydrated alkaline or alkaline earth metal cations are hosted which neutralize the negative charge resulting from isomorphous substitutions of Mg or Al cations within the silicate. Insertion of polymer molecules to prepare “intercalation hybrids” can be carried out by replacing the water hydration molecules in the galleries by polymers containing polar functional groups, using the so called ion-dipole method. A more general technique involves compatibilization of the silicate by intercalation of an organic molecule, typically an organic alkylammonium salt, that replaces the cations in the interlayer galleries to form an organically modified layered silicate (OLS). The aliphatic chain of the OLS favors the intercalation of any type of polymer. Intercalated or delaminated polymer-silicate hybrids are obtained depending on whether the stack organization of the silicate layers is preserved or is lost, with single sheets being distributed in the polymer matrix. The methods currently used for preparing polymer layered silicate (PLS) nanocomposites are: in situ polymerization, from polymer solution, or from polymer melt. Although PLS nanocomposites have been known for a long time, it is the possibility of preparing them by melt intercalation of OLS in processing that is boosting the present interest in these materials and their properties. So far PLS nanocomposites have been characterized by X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, and NMR. Published results on PLS nanocomposites are reviewed concerning their characterization and properties with particular reference to fire retardant behavior.
Model and measurement analysis of springtime transport and chemistry of the Pacific basin

Extensive chemical measurements from the Manna Loa Observatory (MLO) Photochemistry Experiment 2c (MLOPEX 2c) (April 15 to May 15, 1992) field campaign are analyzed in relation to the photochemistry, transport, and physical losses in the Pacific basin utilizing an episodic chemical transport model christened HANK. The budgets of NOy and O 3 are examined in particular, as are model-measurement discrepancies in the NO y budget. For the long-lived species the bias of the simulated means (measured minus simulated divided by measured) of CO 3 CH 4 , C 2 H 6 , C 3 H 8 , O 3 , and NO x is less than 20%. The bias of In ([C 3 H 8 ]/[C 2 H 6 ]) is less than 4%, and the modeled and measured means of C 3 H 8 are not significantly different. H 2 O 2 , CH 3 OOH, and radon agree within a standard deviation. The simulated concentrations of NO y , HNO 3 , and peroxyacetyl nitrate (PAN) are high, while the short-lived hydrocarbons (C 2 H 6 and C 2 H 4 ) are low. Frequency distributions and species' cross correlations are also used to diagnose and evaluate the simulation. Sensitivities in the model formulation are discussed. The results indicate that the subtropics demarcate a transition between a regime characterized by Hadley cell transport to the south and one characterized by rapid isentropic mixing to the north. Vigorous photochemical processing occurs in the remote subtropical Pacific as PAN is converted to NO x , which in turn is converted to HNO 3 . This rapid photochemistry is related to the slope of the isentropic surfaces in the subtropics. It maintains elevated levels of NO x in the remote Pacific, reduced levels of HNO 3 /NO x , and increases the net ozone production. The model anti measurements show that as air masses are processed photochemically (as measured by AGE) the relative concentrations of PAN and NO x decrease, as does PAN/NO y ; corresponding increases occur in HNO 3 , HNO 3 /NO x , and HNO 3 /NO y . In both the model and measurements, H 2 O 2 , CH 3 OOH, and HNO 3 /NO x are tracers of photochemically processed air, while high concentrations of C 3 H 8 , C 2 H 6 , NO x , and PAN are associated with younger air.