Miracle-dz/UniFAR-FTUs huggingface dataset:
Three-dimensional secondary instability of a spatially developing von Kármán vortex street in a far wake

This paper presents studies of a three-dimensional secondary instability of a spatially developing von Kármán vortex street. It develops owing to the nonlinear interaction between a two-dimensional mean far-wake flow and its most unstable disturbances. This forms a nonlinear primary wake flow. Sections of this flow are selected to perform a temporal secondary stability study under the assumption of parallel flow. The eigenvalue characteristics of the secondary instability are compared with the results from the use of a linear primary flow comprising unmodified mean wake flow coexisting with a linear primary fundamental disturbance with an empirical amplitude as a parameter, resulting in a simpler Floquet analysis. The maximum amplification rates occur at about the same spanwise wavenumber for both the nonlinear and linear primary flows, in qualitative agreement. But the amplification rate versus the spanwise wavenumber spectrum are both qualitatively and quantitatively different, the nonlinear primary flow results in a lower magnitude of the amplification rates. Some interpretations of controlled experiments are made, and it is concluded that the two- and three-dimensional disturbances so obtained appeared to be from the primary instability, where the amplification mechanisms come from the unmodified mean flow. A general discussion of the nonlinear interaction between the primary two-dimensional flow and the three-dimensional secondary instability is given, which may well form the basis for further nonlinear studies.
ELIMINATION D'ACIDES ORGANIQUES AROMATIQUES PAR COAGULATION-FLOCULATION AU SULFATE D'ALUMINIUM

La coloration intense et la formation de composes organohalogenes (potentiellement toxiques) sont des problemes qui degradent la qualite des eaux potables. L'origine de ces problemes est essentiellement liee a la presence de la matiere organique laquelle decoule d'origine diverses dans les eaux de surface pour y constituer un milieu tres heterogene (Le Curieux et al., 1996 ; Achour et Moussaoui, 1993). Dans les filieres classiques de traitement d'eaux potables, l'optimisation de la coagulation-floculation (.)
The use of thermal desorption and electron energy loss spectroscopy for the determination of the structures of unsaturated hydrocarbons chemisorbed on metal single-crystal surfaces I. Alk-1-enes on Pt(111)

Thermal desorption combined with mass spectral analysis is used to determine the elemental composition, as a function of temperature, of the adsorbed monolayers of the alk-1-enes, propene, but-1-ene, pent-1-ene and isobutene chemisorbed on the (111) face of a Pt single crystal. Vibrational electron energy loss spectroscopy (EELS) is used to assign structures to the surface species adsorbed at different temperatures. At the lowest temperatures (below 200 K) it is concluded that in each case these alk-1-enes are bonded to the metal surface in the form of di-σ-bonded non-dissociatively adsorbed species. The simplicity of the EEL spectrum from the species derived from isobutene provides additional support for an earlier assignment to the di-σ-adsorbed species for ethylene on Pt(111). At ca. 300 K the EEL spectra and thermal desorption data are consistent with the presence of alkylidyne, M3C(CH2)nCH3 (M = metal; n = 1, 2 or 3) or M3CCH(CH3)2 structures for the chemisorbed species respectively, (M = metal atom). For temperatures above 300 K the thermal desorption results show substantial further loss of hydrogen, a process which commences at lower temperatures the longer the hydrocarbon chain. Near 450 K the thermal desorption data indicate average C:H compositions of approximately C3H2 for the species derived from propene, C4H2 from but-1-ene, and C4H4 from isobutene. The EEL spectra are used to indicate the remaining hydrocarbon functional groups present at this and at higher temperatures. Above 450 K closely similar spectra were obtained from all the straight-chain butenes including the cis- and trans-but-2-enes and buta-1, 3-diene whose spectra are discussed in more detail in the following paper. The EEL spectra indicate the occurrence of C—C bond breaking in general above ca. 500 K, the onset temperatures being somewhat dependent on the adsorbed hydrocarbon.
Stress Buildup and Relaxation During Ion Exchange Strengthening of Glass

A soda-lime-silica glass was subjected to an ordinary ion exchange treatment in molten potassium nitrate at temperatures near and substantially below the strain point of the glass. Stress profiles were measured as a function of exchange temperature and time. At all temperatures, the measurements showed rapid relaxation of the surface stress and the development of a pronounced compression maximum in a short period. A simple viscoelastic model with composition-independent parameters was used to analyze the stress profiles. Neither Maxwell's nor Michelson's relaxation expression could satisfy both characteristics of the residual stress development. Reasons for discrepancies are discussed.
Extraction of low-polarity compounds (with emphasis on coumarin and kaurenoic acid) fromMikania glomerata (‘guaco’) leaves

Five methods for the extraction of low-polarity compounds from Mikania glomerata Spreng. (Compositae) leaves were compared: conventional maceration, maceration with sonication, Soxhlet, and supercritical fluid extraction using hexane (SFE-hexane) or carbon dioxide (SFE-CO2) as the extraction fluid. Evaluation of these methods by relating extraction yield to extraction time showed that SFE-hexane was the most efficient method. SFE-CO2 showed a lower yield, but significantly higher than conventional methods (maceration and Soxhlet). SFE-hexane and maceration gave the highest yield of coumarin, while maceration under sonication gave the highest yield of kaurenoic acid. Among the further chemical constituents of Mikania glomerata leaves identified by high resolution gas chromatography–mass spectrometry were lupeol and lupeol acetate. © 1997 John Wiley & Sons, Ltd.
Air Dynamics Through Filter Media During Air Scour

The dynamics of air motion through filter media under conditions of air scour alone, simultaneous air and subfluidization water flow and simultaneous air and fluidization water flow were studied. Particular combinations of simultaneous air and subfluidization water flows cause the formation and collapse of air pockets within the bed: termed Collapse‐Pulsing. This condition probably created significant abrasion between the filter media grains because the intensity of abrasion is related to the effective stresses between the grains and the magnitude of their relative movement. It is rationalized that collapsepulsing is the probable optimum condition for air scour. Three sands of effective sizes, 0.46 mm, 0.64 mm, and 0.88 mm, were experimentally studied and a simple empirical predictive equation for collapse‐pulsing was established. The equation is also shown to be valid for predicting the condition for a minimum loss of media during backwash. The equation could be used for the design of air scour systems t.
Enhanced activity of a hydrothermally synthesized mesoporous MoS2 nanostructure for high performance supercapacitor applications

In the present work, we have synthesized a mesoporous molybdenum disulfide (MoS2) nanostructure by a facile hydrothermal route for supercapacitor applications. FE-SEM and TEM images confirmed the mesoporous morphologies of the as-prepared samples. The electrochemical measurements showed that the as-prepared mesoporous MoS2 electrode delivered maximum capacitances of 376 and 403 F g−1 at a scan rate of 1 mV s−1 in 1 M Na2SO4 and KCl electrolyte solutions respectively, which indicated that the mesoporous MoS2 nanostructure was a suitable electrode material for supercapacitor applications.
Partial oxidation of ethane by reductively activated oxygen over iron phosphate catalyst

The catalytic oxidation of ethane was carried out at 573–773 Kover iron phosphate catalyst. The oxidation of ethane by oxygenproduced only ethylene and carbon oxides. The co-feed of hydrogenwith oxygen remarkably accelerated the conversion of ethane.Ethanol and acetaldehyde were newly formed by co-feedinghydrogen. The partial oxidation of ethane to ethanol andacetaldehyde can also be achieved by using nitrous oxide as anoxidant. The co-feed of hydrogen with nitrous oxide increasedthe conversion of ethane and the yield to C2oxygenates. Theinvestigation on the reaction paths suggests that ethanol is theprimary product in the oxidation of ethane with hydrogen–oxygengas mixture and with nitrous oxide. Acetaldehyde and ethyleneare produced through further oxidation and dehydration ofethanol, respectively. The highest yield obtained for C2oxygenates was 4.4% (ethanol, 1.4%; acetaldehyde, 3.0%) at 673 K. The kinetic and mechanistic studies suggest that the oxidationof ethane proceeds by a similar reaction mechanism to the oneproposed for the oxidation of methane. Oxygen is activated bythe electrons and protons derived from hydrogen on the catalystsurface, generating a new oxygen species, probably adsorbedperoxide species, effective for the selective oxidation ofethane to ethanol. The same oxygen species can be generatedfrom nitrous oxide by its reductive activation. Both kineticresults and isotopic effects on the conversion of ethane suggestthat the dissociation of the C–H bond of ethane proceeds notablyfaster than the formation of the active oxygen species. Incontrast with ethane, the rate of activation of methane wascomparable to that of the generation of the active oxygen species.
Reduction of CeO2 by hydrogen. Magnetic susceptibility and Fourier-transform infrared, ultraviolet and X-ray photoelectron spectroscopy measurements

The reduction of CeO2 by hydrogen has been studied from 300–1200 K by several complementary techniques: temperature-programmed reduction (TPR) and magnetic susceptibility measurements, Fourier-transform infrared (FTIR), UV–VIS diffuse reflectance and X-ray photoelectron (XP) spectroscopy. Two CeO2 samples were used with B.E. T. surface areas of 115 and 5 m2 g–1, respectively. The concentration of Ce3+ was determined in situ by measuring the magnetic susceptibility and the CeIII photoemission line. The reduction began at 473 K, irrespective of the initial surface area of the ceria. In the case of the low-surface-area sample, an intermediate reduction step was observed between 573 and 623 K, corresponding to the reduction of the surface. This intermediate step was less easily observed in the case of the high-surface-area ceria. In both cases, the reduction led to a stabilised state with the formal composition CeO1.83. Temperatures higher than 923 K were required to reduce the ceria further. The surface CeIII content determined by XPS was close to that determined by magnetic susceptibility measurements. The intensity of the 17 000 cm–1 band in the UV–VIS reflectance spectrum also varied with the degree of reduction. Finally, the evolution of the surface species observed by IR spectroscopy was in good agreement with the results from the other techniques. The IR results indicated large changes in the concentration and nature of both the hydroxyl and the polydentate carbonate species during the reduction process. The adsorption of oxygen on samples previously reduced to the composition CeO1.83 led to almost complete reoxidation at room temperature. The state of the initial B.E. T. surface did not influence the oxidation process. A slight excess adsorption of oxygen was evident on the surface. This was thermodesorbed at 380 K under vacuum.
Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

The sedimentation of HNO(3) containing Polar Stratospheric Cloud (PSC) particles leads to a permanent removal of HNO(3) and thus to a denitrification of the stratosphere, an effect which plays an important role in stratospheric ozone depletion. The polar vortex in the Arctic winter 2009/2010 was very cold and stable between end of December and end of January. Strong denitrification between 475 to 525K was observed in the Arctic in mid of January by the Odin Sub Millimetre Radiometer (Odin/SMR). This was the strongest denitrification that had been observed in the entire Odin/SMR measuring period (2001-2010). Lidar measurements of PSCs were performed in the area of Kiruna, Northern Sweden with the IRF (Institutet for Rymdfysik) lidar and with the Esrange lidar in January 2010. The measurements show that PSCs were present over the area of Kiruna during the entire period of observations. The formation of PSCs during the Arctic winter 2009/2010 is investigated using a microphysical box model. Box model simulations are performed along air parcel trajectories calculated six days backward according to the PSC measurements with the ground-based lidar in the Kiruna area. From the temperature history of the backward trajectories and the box model simulations we find two PSC regions, one over Kiruna according to the measurements made in Kiruna and one north of Scandinavia which is much colder, reaching also temperatures below T(ice). Using the box model simulations along backward trajectories together with the observations of Odin/SMR, Aura/MLS (Microwave Limb Sounder), CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and the ground-based lidar we investigate how and by which type of PSC particles the denitrification that was observed during the Arctic winter 2009/2010 was caused. From our analysis we find that due to an unusually strong synoptic cooling event in mid January, ice particle formation on NAT may be a possible formation mechanism during that particular winter that may have caused the denitrification observed in mid January. In contrast, the denitrification that was observed in the beginning of January could have been caused by the sedimentation of NAT particles that formed on mountain wave ice clouds.
Poly(Lactic Acid)-Based Blends With Tailored Physicochemical Properties for Tissue Engineering Applications: A Case Study

Binary blends of poly(L-lactic) acid (PLLA: 201790 Da) and poly(lactide-co-glycolide) (PLGA) (LA:GA = 50:50 mol:mol; 32030 Da) with various compositions were prepared. Physicochemical properties of PLLA/PLGA blends were analyzed. Blends showed a biphasic morphology, with distinct glass transition temperatures, which only slightly approximated compared to pure polymers. Analysis of tensile mechanical properties through the Kerner-Uemura-Takayanagi model showed compatibility for PLLA/PLGA 75/25 blend. Rapid degradation of PLGA phase (2–8 weeks) in PLLA/PLGA 75/25 blend led to porous samples, which appear promising for drug delivery and tissue engineering. A limited inflammatory reaction resulted from subcutaneous implantation of PLLA/PLGA 75/25 in Balb-c mice. GRAPHICAL ABSTRACT
Parâmetros relacionados com a erosão hídrica sob taxa constante da enxurrada, em diferentes métodos de preparo do solo

Tillage influences both surface and subsurface soil physical conditions, and consequently the values of the factors related to the rainfall-water erosion process. A field experiment using simulated rainfall was conducted from October, 1999 to May, 2000, in the Planalto Sul Catarinense region, Lages, Santa Catarina State, Brazil, in order to evaluate some of the factors related to the rainfall-water erosion process under steady runoff-rate, with three different soil tillage methods. The soil used in the study was a clayey Typic Hapludox with 0.14 m m-1 slope at the experimental site. The evaluated treatments consisted of: (a) reduced tillage (chiseling + disking), (b) typical conventional tillage (plowing + double-disking), and (c) modified conventional tillage (plowing + double-disking + double hand-harrowing). The first two treatments were applied in continuously cultivated soil and the last one in continuously uncultivated-soil (control treatment). Both the soil surface random-roughness and soil surface residue cover were characterized in the treatments through measurements immediately before and after tillage, on the day before simulated rainfall application. The rainfall test was applied by the time of soybean planting, at a constant intensity of 64 mm h-1 and varying durations (until completing 30-min of constant runoff in each treatment). Soil tillage increased the random-surface roughness and decreased surface cover to different degrees, depending on the type of equipment. Reduced tillage was the most effective treatment in terms of both increasing random surface roughness and maintaining the soil surface cover. The periods until starting runoff and reaching runoff-peak were relatively long and little affected by tillage treatments. Runoff velocity, sediment concentration and size of eroded sediments in the runoff-water, and soil loss rate increased with the decrease in both surface roughness and surface cover, while rainfall-water infiltration in the soil decreased. Runoff discharge and its associated runoff coefficient - parameter C in the Rational Equation - increased as surface roughness and surface cover decreased.
Maize growth and uptake of phosphate and copper at different ambient phosphate concentrations

Abstract Response of maize to 10, 100, and 1,000 μM P was studied in solution culture. Maize growth was maximum at 100 μM P while the root/shoot ratio was the highest at 10 μM P. Increase in the supply of P in the solution promoted its uptake and decreased the P utilization rate. Both transport to shoot and uptake rate of Cu increased with the increase of the solution P concentrations. The proportion of Cu retained in roots (65%) did not vary with differential Cu uptake at three P levels. Copper and P concentrations in roots were positively correlated.
Studies on the Selective Separation of Ir(IV), Ru(III) and Rh(III) from Chloride Solutions using Alamine 336 in Kerosene

Abstract The liquid–liquid extraction of Ir(IV), Ru(III), and Rh(III) from chloride solution was studied under different conditions of aqueous‐ and organic‐phase component concentrations using Alamine 336 (A336) as an extractant. The differences obtained in the extraction of individual metals at different concentrations of A336 and HCl in the organic and aqueous phases respectively were used to mutually separate the three metals. A two‐step separation scheme was proposed. In the first step, Ir(IV) was selectively extracted using a solvent comprised of 0.1% A336 and 10% TBP in kerosene. In the second step, Ru(III) was quantitatively extracted using a solvent comprised of 5% A336 and 10% TBP in kerosene (all % v/v). Rh(III) was selectively left behind in the raffinate. Under controlled experimental conditions, we were able to eliminate the base metal ions commonly associated with Ir, Ru, and Rh during the extraction and the stripping process.
Correction of resistance to penetration by pedofunctions and a reference soil water content

The soil penetration resistance is an important indicator of soil compaction and is strongly influenced by soil water content. The objective of this study was to develop mathematical models to normalize soil penetration resistance (SPR), using a reference value of gravimetric soil water content (U). For this purpose, SPR was determined with an impact penetrometer, in an experiment on a Dystroferric Red Latossol (Rhodic Eutrudox), at six levels of soil compaction, induced by mechanical chiseling and additional compaction by the traffic of a harvester (four, eight, 10, and 20 passes); in addition to a control treatment under no-tillage, without chiseling or additional compaction. To broaden the range of U values, SPR was evaluated in different periods. Undisturbed soil cores were sampled to quantify the soil bulk density (BD). Pedotransfer functions were generated correlating the values of U and BD to the SPR values. By these functions, the SPR was adequately corrected for all U and BD data ranges. The method requires only SPR and U as input variables in the models. However, different pedofunctions are needed according to the soil layer evaluated. After adjusting the pedotransfer functions, the differences in the soil compaction levels among the treatments, previously masked by variations of U, became detectable.
Composition of the Essential Oil from the Leaves of Palma Real (Tanacetum vulgare L) from Perú

The present work presents the chemical composition of the essential oil of Tanacetum Vulgare L from Peru. The chemical composition was compare with the chemical composition of the essential oils of Tanacetum Vulgare L reported in others papers. Fresh leaves of Tanacetum Vulgare L were hydrodistiled in a Clevenger type apparatus. GC analyses were carried out using two gas-cromatographs, a Hewlett-Packard 6890 gas-chromatograph equipped with a flame ionization detector and a GC-MS Hewlett-Packard 5890 gas-chromatograph series II coupled with a Hewlett-Packard 5989 B mass-spectrometer. Identities of compounds were established by use of on-line Willey275/ NBS75k/ NIST mass spectral data bases and literature MS data.
Permeability, Solubility, and Diffusivity of Methane and Butane in Diphenylsiloxane-Dimethylsiloxane Copolymer Membranes

Permeation and sorption of methane and n-butane gases in polydimethylsiloxane (PDMS) and diphenylsiloxane-dimethylsiloxane (DPh-DM) block copolymer membranes were studied at room temperature and different upstream pressures. The membranes were prepared via room temperature vulcanization of vinyl terminated siloxanes through platinum catalyzed hydrosilylation reactions by mixing stoichiometric amounts of polymer, crosslinker, and catalyst, and casting of the mixture solutions with hexane. Composite membranes of polysiloxanes on a polyacrylonitrile microporous support were synthesized for permeation experiments and single layer dense films were used in sorption experiments. The effect of upstream pressure on permeability, solubility, and diffusivity of these membranes was evaluated. It was found that selectivity of the DPh-DM copolymer membrane for n-C4H10 relative to CH4 was up to 19% higher than that in PDMS membrane. Both solubility and diffusivity selectivities had positive contributions in permselectivity improvement. The improvement in selectivity was attained with less than a 6% decrease in permeability of n-C4H10. Up to 11% improvement in selectivity was also obtained in mixed gas experiment.
Aflatoxin Decontamination of Artificially Contaminated Feeds by Sunlight, γ-Radiation, and Microwave Heating

SUMMARY The efficiency of decontamination of aflatoxin residues in poultry feeds through exposure to sunlight (solar radiation), γ-radiation ( 60 Co), and microwave heating were investigated in artificially contaminated feed samples. Photodegradation of aflatoxin by sunlight has been found to cause a significant (P < 0.05) decrease in both B1 and the total aflatoxins. Moreover, the degrees of aflatoxins were dependent on exposure time. Both aflatoxin B1 and total aflatoxins were decreased when feed samples exposed to sunlight by 42.3, 39.9, 75.5, and 65.9% for 3 and 30 h of direct sunlight of the treatment T1, whereas feed samples subjected to γ-irradiation and microwave heating caused a significant (P < 0.05) decrease in aflatoxin B1 contents by 42.7 and 32.3% for γ-irradiation and microwave heating (T3 of 25 kGy and 10 min of microwave heating), respectively. Therefore, the solar radiation was more effective in aflatoxin B1 reduction when compared with γ-irradiation and microwave heating.