Total Particle Surface Area Research Articles

Thermohydraulic explosions in phreatomagmatic eruptions as evidenced by the comparison between pyroclasts and products from Molten Fuel Coolant Interaction experiments

Thermohydraulic explosions were produced by Molten Fuel Coolant Interaction (MFCI) experiments using remelted shoshonitic rocks from Vulcano (Italy). The fragmentation history and energy release were recorded. The resulting products were recovered and analyzed with the scanning electron microscope. Fine particles from experiments show shape and surface features that result from melt fragmentation in brittle mode. These clasts relate to the thermohydraulic phase of the MFCI, where most of the mechanical energy is released; they are here called “active” particles. The total surface area of such particles is proportional to the energy of the respective explosions. Other particles from experiments show shape and surface features that result from melt fragmentation in a ductile regime. These fragments, called “passive” particles, form after the thermohydraulic phase, during the expansion phase of the MFCI. In order to verify thermohydraulic explosions in volcanic eruptions, we compared experimental products with samples from phreatomagmatic base‐surge deposits of Vulcano. Ash particles from the experiments show features similar to those from the deposits, suggesting that the experiments reproduced the same fragmentation dynamics. To achieve discrimination between active and passive particles, we calculated shape parameters from image analysis. The mass of active particles in base‐surge deposits was calculated. As the material properties for the natural samples are identical to the experimental ones, the energy measurements and calculations of the experiments can be applied. For a single phreatomagmatic eruption at Vulcano, a maximum mechanical energy release of 2.75 × 1013 J was calculated, representing a TNT analogue of 6.5 kt.

Estimation of the adsorption state of nonionic emulsifier molecules onto styrene-methacrylic acid copolymer particles by in situ 1 H NMR measurements

The adsorption behavior of poly(oxyethylene) nonyl phenyl ether nonionic emulsifier molecules onto polystyrene (PS) and styrene–methacrylic acid copolymer [P(S-MAA)] particles dispersed in D2O was evaluated by in situ 1H NMR measurements at room temperature. The resonance due to the protons of the emulsifier molecules was only observed. Normalized NMR integrals of the resonance due to the protons of hydrophobic groups (nonyl and phenyl groups) and the hydrophilic group, poly(oxyethylene) chain, at a certain concentration of the emulsifier decreased with an increase in the total surface area of the PS particles dispersed in the system. The decrease for the hydrophobic groups was much larger than that for the hydrophilic groups. In the dispersion system of P(S-MAA) particles, ionized carboxyl groups at the particle surface decreased the amount of the emulsifier adsorbed.

Effects of Singapore soil type on bioavailability of nutrients in soil bioremediation

The biodegradation of phenanthrene by Pseudomonas putida (ATCC 17484) was studied in six different synthetic soils representing the chemical compositions of six Singapore soil types. The nutrients used were ammonium nitrate to provide nitrogen, potassium dihydrogen phosphate (KH 2PO 4) and phenyl phosphate (PP) disodium salt to provide phosphorus. Sorption isotherms of the nutrients in each soil type were determined. Bioavailability of nutrients is measured by the ratio of the rate of biodegradation in the presence of nutrients to that in the absence of nutrients. The bioavailability was found to correspond closely to the KH 2PO 4 sorption capacity of a soil. Increasing KH 2PO 4 increased the biodegradation rate of phenanthrene across all soil types, indicating that phosphorus was limiting. The organic phosphorus compound, PP, has greater sorption ability than KH 2PO 4. It was tested as a substitute for KH 2PO 4 in the biodegradation of phenanthrene and was found to increase the bioavailability of phosphorus. It is proposed that bacteria attach themselves on the external surfaces of soil particles and utilize the nutrients sorbed there. The bioavailability of phosphorus from both KH 2PO 4 and PP was well correlated with the effective concentration of phosphorus—defined by the product of the equilibrium concentration of phosphorus sorbed in a soil and the fraction of external surface area over total surface area of soil particles. The Monod model fits the above correlation reasonably well. This study can be applied to the bioremediation of local soils in determining the amount of nutrients to use.

Activity of PtRuMeO x (Me = W, Mo or V) catalysts towards methanol oxidation and their characterization

The activity of unsupported ternary PtRuMeO x (Me=W, Mo, V) high surface area catalysts towards methanol oxidation under fuel cell relevant conditions, at constant potential and elevated temperature of 60 °C, was investigated by the thin-film electrode method. CO-stripping experiments for actual surface area detection, using differential electrochemical mass spectrometry (DEMS) to evaluate the amount of adsorbed CO, show that the electrochemically active area of the particle surface is significantly smaller than the total particle surface area determined by N 2 BET measurements, indicating that part of their surface consists of MeO x . The specific surface activity of the catalysts towards methanol oxidation at 60 °C, normalized to the current density per square centimeter of electrochemically active noble metal surface, decreases in the order PtRuVO x >PtRuMoO x >PtRu>PtRuWO x =PtRu (E-TEK). Apparently, the surface oxide leads to an acceleration of the methanol oxidation reaction, which is, however, partly compensated by a decrease in active surface area.

Comparison of protein loaded poly(?-caprolactone) microparticles prepared by the hot-melt technique

This study was systematically designed to compare bovine serum albumin (BSA) loaded poly(epsilon-caprolactone) (PCL) microparticles based on a 2(3) factorial experiment. The microparticles were prepared by the holt-melt technique without using an organic solvent for polymer solubilization. The influence of the particle size of protein, protein/polymer ratio, and hydrophilic PEG on the surface morphology, particle size as well as the yield of PCL microparticles, encapsulation efficiency of BSA, and in vitro release properties were investigated. The structure of BSA remained its integrity using this technique. The mean particle size of BSA-loaded microparticles were in the range of 12.7 +/- 0.1-16.9 +/- 0.8 microm, and all of the particles were smooth on the surface. The production yield of microparticles and the encapsulation efficiencies were high, and the values were in the range of 94.8 +/- 1.6%-98.1 +/- 1.0% and 94.9 +/- 9.6%-98.6 + 0.3%, respectively. The burst release of BSA was in the range of 8.2 +/- 0.4%-61.0 +/- 0.8%, which strongly depended on the formulation. None of three variables affected the yield of microparticles prepared from eight formulations (p > 0.05). However, the particle size of BSA significantly affected the size and the burst release as well as the cumulative release of protein in these microparticles (p < 0.05). The initial loading of BSA in terms of BSA/PCL ratio and the amount of PEG blended with PCL significantly affected all of the properties, except the yield (p < 0.05). The smaller the particle size of the BSA, the smaller the size of the resulting microparticles. Since the total surface area of the small particles was larger than that of the large particles, this accounted for the high burst release of protein from the microparticles encapsulating triturated-BSA.

Benzenecarboxylate surface complexation at the goethite (α-FeOOH)/water interface: II. Linking IR spectroscopic observations to mechanistic surface complexation models for phthalate, trimellitate, and pyromellitate

A study combining information from infrared spectroscopy and adsorption experiments was carried out to investigate phthalate, trimellitate, and pyromellitate complexes at the goethite (α-FeOOH)/water interface. Infrared spectra showed evidence for inner-sphere complexes below pH 6 and outer-sphere complexes in the pH range 3 to 9. Normalized infrared peak areas were used as a semi-quantitative tool to devise diagrams showing the molecular level surface speciation as a function of pH. Surface complexation models that simultaneously predict these diagrams, the proton balance data and the ligand adsorption data were developed with surface complexation theory. Surface complexation modeling was carried out with a Charge Distribution Multisite Complexation Model (CD-MUSIC), assuming goethite particles with surfaces represented by the {110} plane (90% of total particle surface area) and by the {001} plane (10% of total particle surface area). Inner-sphere complexes were described as mononuclear chelates at the {001} plane, whereas outer-sphere complexes were described as binuclear complexes with singly coordinated sites on the {110} plane. The Three-Plane Model (TPM) was used to described surface electrostatics and to distribute the charges of the inner- and the outer-sphere complexes on different planes of adsorption.

Bimodal particle size distribution polymer/oligomer combinations for printing ink applications

This paper describes a study in which anionically stabilised acrylic latices with a bimodal particle size distribution, produced by blending polymer particles of 50 and 350 nm in different blend ratios, are blended with oligomers. Reversibility, rheology, drying behaviour, film formation and blocking resistance of these systems were studied Reversibility appears to show two regions of linear dependence on the total particle surface area. The lower the surface area, the lower the amount of oligomer needed for good reversibility. The rheological data was fitted by the Krieger–Dougherty equation and it appeared that both in the presence and absence of oligomer an 80/20 large/small blend exhibited the highest maximum packing fraction. Short drying times were obtained with bimodal blends at high solids content and the drying profiles could be explained by the Croll model. The presence of oligomer was shown to exhibit a positive effect on film formation and when the oligomer is hard, the blocking resistance is already very good at low oligomer content, resulting in a very good MFT/blocking resistance balance. The latter can also be obtained when as well the size as the T g of the polymer particles is varied.

INHALATION OF POORLY SOLUBLE PARTICLES. II. INFLUENCE OF PARTICLE SURFACE AREA ON INFLAMMATION AND CLEARANCE

In this article the volumetric overload hypothesis, which predicts the impairment of clearance of particles deposited in the lung in terms of particle volume, is reevaluated. The degree to which simple expressions of retained lung burden explain pulmonary responses to overload was investigated using data from a series of chronic inhalation experiments on rats with two poorly soluble dusts, titanium dioxide and barium sulfate. The results indicated that the difference between the dusts in the level of inflammation and translocation to the lymph nodes could be explained most simply when the lung burden was expressed as total particle surface area. The shape of the statistical relationship for both lung responses indicated the presence of a threshold at approximately 200–300 cm2 of lung burden. On the basis of this and other similar results, a hypothesis regarding a generic mechanism for the impairment of clearance and associated lung responses is proposed for such ''low-toxicity'' dusts.

Histiocyte reaction in rabbit femurs to UHMWPE, metal, and ceramic particles in different sizes.

To assess the histologic reaction caused by biomaterial particles in different sizes around the bone-implant interface, we examined ultra-high molecular weight polyethylene (UHMWPE, average diameter of 11 microm), UHMWPE (99 microm), cobalt-chromium alloy (Co-Cr, 3.9 microm), stainless steel (SUS316L, 3.9 microm), alumina ceramics (3.9 microm), titanium alloy (Ti, 3.5 microm), Co-Cr (0.03 microm), and Ti (0.03 microm). After the longitudinal groove on a polymethylmethacrylate plug was filled with one type of the particles, the plug was inserted into the medullar canal of the distal end of rabbit femurs, and tissue block was resected 4 and 12 weeks after the insertion. Histiocytes were markedly accumulated around the particles of UHMWPE (11 microm), Co-Cr (3.9 microm), SUS316L (3.9 microm), Co-Cr (0.03 microm), and titanium alloy (0.03 microm). Around the UHMWPE particles (99 microm), a slight histiocytic reaction and bone formation were observed. Particles of alumina ceramics (3.9 microm) and titanium alloy (3.5 microm) which were in phagocytosable sizes also had few histiocytic reactions. Statistically, the material difference was more strongly related to the histiocyte reaction than to the particle size and calculated total surface area of particles. Our findings demonstrate that particles of different biomaterials and in different sizes induce different foreign-body histological reactions.

Organic contribution to sub-micron aerosol evolution over a boreal forest—a case study

During the spring and summer of 1998 and spring of 1999 three major international campaigns have been performed at the SMEAR II Station (Station for Measuring Forest Ecosystem–Atmosphere Relations) in Hyytiala, Finland. The measurements have been conducted as part of the BIOFOR programme, the objectives of which were to elucidate the main factors leading to nucleation and growth of new particles over forested regions. For typical nucleation events encountered in this environment, total particle concentration and surface area reduce rapidly due to mixing processes in the late morning prior to a nucleation event. After this reduction in pre-existing aerosol, ultra-fine particles (3–10 nm) appear, and grow rapidly (over several hours) towards accumulation mode sizes (>100 nm). Volatility measurements of new particle composition, once they have grown into accumulation mode sizes, illustrate a significant organic contribution to aerosol mass. Suggested contributors to this organic mass are pinic acid and/or cis-pinoic acid.

Variation in Characteristics of Abraded Roadway Particles as a Function of Particle Size: Implications for Water Quality and Drainage

Storm-water runoff from highway pavement is capable of mobilizing and transporting a wide gradation of particulates and solids. A significant fraction of this particulate matter is generated from traffic activities, including the abrasion between tires and pavement. Particulate accumulation and characteristics from an urban Interstate pavement site are investigated. The southbound asphalt pavement section studied consisted of four traveled lanes and two paved shoulders with a measured average daily traffic of 110,000. The pavement section has a transverse slope of 0.020 m/m and a longitudinal slope of 0.004 m/m. Recovery of deposited particulate matter indicates that accumulation of particulate matter along the east paved shoulder (the downslope shoulder) is significantly greater than that along the the west paved shoulder (the upslope shoulder) or the pavement. Particles larger than 25 μm were separated mechanically to generate particle size distributions (PSDs) and also to separate particles for further analysis. The east shoulder PSDs were consistently coarser across the entire size gradation than the west shoulder and pavement PSDs. Particle specific gravity ranged from 2.70 to 3.01 g/cm3 across all gradations. Particle specific surface area increased with decreasing particle size for all gradations. In contrast, total particle surface area decreased with decreasing particle size. Integration of metal element concentration (in micrograms per gram) of zinc, copper, cadmium, and lead with the mass fraction of each particle size demonstrates that most of the metal mass is associated with the coarse to mid-range-size particles. Study results are useful for design of roadway drainage appurtenances and water quality control devices that clarify storm water mainly through the separation of particles.

Latitudinal differences in the influx of microscopic charred particles to lake sediments in Finland

Forest fires produced charcoal throughout the Holocene and charcoal was preserved in lake sediments. This study compares differences in sedimentary charcoal between southern and northern Finland. Yearly influx of the total surface area of the charcoal particles (μm2 cm-2 yr-1) was estimated at different latitudes: two lakes from southern Finland (60° 21'N, 60° 59'N), two from the Kuusamo area (66° 21'N), NE Finland and one lake from NW Finnish Lapland (68° 40'N). The results show that the mean amount of charcoal deposited in southern Finland was about 10 times higher than that from Kuusamo and 100 times higher than that from NW Finnish Lapland. These differences existed for the whole Holocene and were accompanied by changes in temperature and humidity, as well as drastic changes in forest type. It is suggested that the climatically induced difference in forest biomass at different latitudes accounts for the differences in charcoal influx. Since high-resolution charcoal analyses are not available, it is not clear if the fires were also less frequent in the Kuusamo area; however, there is evidence from Lapland of very long intervals between fires.

Relationship between fracture toughness, fracutre path, and microstructure of 7050 aluminum alloy: Part II. Multiple micromechanisms-based fracture toughness model

A multiple micromechanisms-based model is developed to quantitatively relate the fracture toughness of partially recrystallized 7XXX aluminum alloys to their fracture surface morphology. The model is verified using the experimental data on partially recrystallized 7050 alloy reported in the companion article. It is then used to obtain a quantitative relationship between the fracture toughness and microstructural attributes. The model relates fracture toughness to microstructural parameters such as degree of recrystallization, grain size of recrystallized grains, thickness of recrystallized regions, total surface area of the constituent particles per unit volume, and microstructural anisotropy. The model predicts the changes in the fracture toughness with the specimen orientation.

ニッケル粒子分散アルミナ系複合材料の作製と力学的特性

Fracture toughness and other mechanical properties of alumina matrix composite reinforced with nickel particles were measured. Nickel/alumina composites up to 25vol% of nickel contents were prepared by sintering in fine graphite powder bed under N2 gas atmosphere. Vibration was also applied during sintering to promote the dispersion of nickel particles in alumina matrix, using a high-frequency apparatus. Decrease in Young's modulus and three-point bending strength was observed with increasing nickel content. The fracture toughness, on the other hand, measured by SEVNB method increased with increasing nickel content. The fracture energy of composite was estimated by Griffith equation according to the observed fracture toughness and Young's modulus. The fracture energy increased in proportion to the total surface area of nickel particles comprized in the unit volume of composite. Increase in fracture energy corresponded to the formation of microcracks, which generated on nickel particles in the frontal process zone of composite. Decrease in bending strength was explained by the formation of large defects in composite, due to the large pore, decreasing of interparticle spacing or aggregation of nickel particles.

Retrieval of aerosol properties from boundary layer extinction measurements with a DOAS System

Boundary layer trace gas and particulate extinction measurements in the wavelength region from 320 nm to 680 nm have been performed by means of a differential optical absorption spectroscopy (DOAS) system at Cape Arkona (Island Rügen/Germany). The wavelength‐dependent extinction coefficient σe(λ) is determined from the attenuation of radiation along two paths of different lengths. Nearly simultaneous recording of the concentrations of O3 and NO2 within the same air mass allows a correction of their contribution to σe(λ). The extinction coefficients are compared with volume scattering coefficients measured by an open integrating nephelometer. Differences between the measurements can be attributed to atmospheric inhomogeneities. A simplified model involving monomodal log‐normal distributions is applied to approximate the total particle surface area concentration and an upper limit of the accumulation mode radius. This allows a rough estimate of the particle number concentration. During the summer of 1995 the mean (median) surface area concentration was about 350 (250) µm²/cm³, and the particle number concentration ranged from about 100 cm−3 to some 1000 cm−3.

Improvement of Heat Transfer in a Packed-Bed Reactor for a Chemical Heat Pump Using Sodium Carbonate Decahydrate Dehydration

To improve the heat transfer characteristics of a gas−solid packed-bed reactor, an inert solvent was added to the reactor. For sodium carbonate decahydrate dehydration, used in a chemical heat pump, n-pentanol was chosen as a solvent, and the dehydration rate in the solvent was measured. The dehydration rate was found to be proportional to the total surface area of the decahydrate particles, and the rate equation was determined. Particle size distribution (less than 400 μm) remained unchanged for a three-time cyclic operation. The packed-bed of decahydrate with n-pentanol solvent showed considerable improvement in heat transfer characteristics compared with the case having no solvent, and cold heat generation was more than doubled. A simulation study showed that the addition of n-pentanol may make it possible to construct a high-performance heat pump with cold storage capability, attaining 280 K in less than 5 s and total heat release within 1600 s.

New particle formation at a remote continental site: Assessing the contributions of SO2 and organic precursors

Ultrafine aerosols, with diameters less than 10 nm, nucleate from gas phase species. The composition of newly formed ultrafine atmospheric aerosols is not known with certainty; new particles have variously been conjectured to be sulfates, organic compounds, and sulfate/organic mixtures. The 1993 Tropospheric OH Photochemistry Experiment at Idaho Hill, Colorado, provided an opportunity to examine the question of which class of compounds, i.e., sulfates or organics, make the major contribution to new particle formation in the unpolluted troposphere. This study compared the production rates of sulfuric acid (from the oxidation of sulfur dioxide) and oxidized organic compounds to gauge their relative contributions to the formation of ultrafine particles. Potential organic precursor species examined in this study were the naturally occurring terpenes α– and β pinene, and the anthropogenic hydrocarbons toluene, m‐xylene, ethyl benzene, 1,2,4 trimethyl benzene, and methylcyclohexane. The calculated production of oxidized organics appeared well correlated with total particle surface area and volume, suggesting that at least some of the organic compounds formed in gas phase reactions condensed upon the preexisting aerosol. New particle formation was found to be more highly associated with elevated production of gas phase sulfuric acid (via the SO2‐OH reaction) than with production of oxidized organic products, although data from one day, during which sulfuric acid production and total aerosol surface area were both lower than usual, provided evidence for the involvement of terpene species in new particle formation. The results suggest that for this continental site, sulfuric acid was probably responsible for most of the observed new ultrafine particle formation. Low‐volatility organic compounds may have caused particle formation under the right conditions, but were more likely to condense upon preexisting particles.

Experimental Investigation of the De-inking of Recycled Newspaper Using Plastic Particles

The effect of the type of plastic particles, its average diameter, and its total surface area on the de-inking of recycled newspaper was investigated. It was found that plastics vary in their ability to remove ink. Among the various types of plastics examined, low density polyethylene (QAPCO) was found to have the largest capacity of ink removal. Ink removal versus plastic particle size was found to go through a maximum. Studying the effect of the total surface area of plastic particles on de-inking shows that a limiting surface area exists above which no more ink can be separated.

Effect of Surfactant Configurations on Miniemulsion Polymerization

In the adsorbed state, the molecular area (A c ) of fatty alcohol (FA) decreases and the hydrodynamic layer thickness (δ) of mixedsurfactant (FA + sodium dodecyl sulfate, SDS) increases with increasing alkyl chain length of FA. In bulk solution, the hydrodynamic volume of mixed-surfactant (FA+ SDS) increases with increasing alkyl chain length of FA. In both states the FAs were solubilized by SDS. These results reflect that a FA with a shorter alkyl chain length can stabilize a larger total particle surface area on latex and form smaller particles. The increase in the content of FA leads to increases in δ and particle size, and a decrease in polymerization rate. It may be plausible to consider that the FA has a rather rigid configuration in water. The degree to which the size of monomer droplets can be reduced may be related to the rigidity of the FA

Geocryological‐engineering properties of cryogenic weathering crusts in deposits in northern Yakutia

Abstract The article presents the results of a comparative study of the cryogenic weathering layer (in terms of granulometric composition and cryogenic texture) in two contrasting environments. One site, located at the summit of Turku Mountain near Kular in northern Yakutia, represents a “low‐dynamic”; weathering environment in an area of gentle relief and is characterized by cryogenic breakdown of the bedrock into a deep layer of sandy loam. The other site, near Mount Churpunn'ya, represents a more dynamic cryogenic weathering environment and the profile here consists mainly of coarse blocky material from which the fines have been almost entirely removed by solifluction. The author demonstrates that variations in the specific surface index (total surface area of particles per unit mass of the material) provides a useful index for assessing the depth of bedrock affected by cryogenic weathering.