Evaluation of Construction Practices That Influence the Bond Strength at the Interface between Pavement Layers

This study investigated the influence of several construction practices on the bond strength at the interface between pavement layers. These practices included the surface treatment, curing time, residual application rate, and equipment tracking. Three tests were performed for estimating the bond strength between an existing hot mix asphalt (HMA) and a newly constructed HMA overlay, namely the Florida Dept. of Transportation shear tester, the University of Texas at El Paso pull off test, and the torque bond test. Testing involved a CSS-1 type emulsion as the tack coat. The results from the three tests were statistically analyzed. Generally, milling provided a significantly better bond at the interface between the existing surface and the new overlay. Curing time had a minimal effect on the bond strength. The results indicated that the absence of tack coat did not significantly affect the bond strength at the interface for the milled sections, whereas it severely decreased the strength for the nonmilled sections. The results also showed that increasing the residual rate of tack coat did not generally affect the bond strength at the interface.     

Characterization of Emulsion Wax Curing Agent as Bond-Breaker Medium in Jointed Concrete Pavement

Bond-breaker media have been used with success to reduce and minimize undesirable cracks reflecting from cement-treated or lean-concrete subbases (LCSs). The common bond-breaking media include (1) emulsion slurry seal; (2) 30 to 60-mm-thin asphalt concrete; (3) one or two applications of wax-based curing compounds; (4) one or two layers of polyethylene sheets; and (5) geotextile. The cost differences among different bond-breaking media are significant for a highway project over 200 km long. Different types of tests (British pendulum friction, push off, pullout, and torsion) were performed to determine the cost-effectiveness of bond-breaking media. It was found that the bond stress had been reduced by approximately 90% when either emulsion wax curing compound (EWCC) or emulsion slurry seal was used. The results from the British pendulum, push-off, pullout, torsion, and cost analyses indicate that EWCC is the most cost-effective bond-breaker medium. Based on the observations from the laboratory testing and field trial section, the EWCC application rate was selected at 0.4?L/m2. As evident from the push-off and torsion test results, the effectiveness of the EWCC as a bond-breaker medium decreased with time. Thus, a second application of EWCC is required if the LCS base has been exposed to the environment for more than 14 days. The 216-km project was successfully constructed with EWCC. It resulted in a more than $7 million savings by using EWCC instead of emulsion slurry seal. No distress or cracking has been observed after the section was opened to traffic for more than 1 year.     

Observation on Particulate Matter over a Period of 3 Years at Kaikhali (22.022°N and 88.614°E) inside a Special Mangrove Ecosystem: Sundarbans

Measurement of particulates [respirable particulate matter (RPM or PM10), fine RPM (PM2.5), non-RPM (NRPM), and total suspended particulate matter (TSPM)] were carried out on a campaign basis over a period of 3 years (2003–2006) at Kaikhali (22.022°N and 88.614°E) inside one of the world’s largest mangrove delta region—“The Sundarbans.” Considering the toxic potential of the particulate fractions, the foremost objective of this study was to determine the particulate concentrations during different parts of the year as well as to ascertain the trend of occurrence of the particulate fractions in an area of rich and unique biodiversity. Moreover, as the area had no past records on particulate data over a decade, the other important objective of the study was to prepare substantial database for the area for the present time. The average range of PM10, PM2.5, NRPM, and TSPM for the period from 2003–2006 has been found to be (57–118), (35–80), (10–25), and (73–135)?μg?m?3 respectively. The data obtained for the finer particulate fractions have been compared with some previous studies in India. In addition to the particulate fractions, meteorological parameters such as wind speed, wind direction, and temperature were also recorded to accomplish proper interpretation of the data. The requisite statistical parameters (standard deviation, average, and range) for the particulate fractions have also been calculated.     

Effects of cytochalasin H on the morphogenetic movements of the embryos of Microhyla ornata

The intensity of radioautographic reactions in Ilford L4, Sakura NR-H2 and Kodak NTE emulsions was compared after exposure in either dry air or dry helium gas at 4 degrees C to test the stability of latent images in the presence or absence of oxygen. A light proof container is described in which slides bearing radioactive sections coated with the three emulsions were exposed in dry helium at a constant pressure of approximately 0.5 atm. The comparison of air and helium atmospheres during exposure of radioautographs was estimated qualitatively for 125I-labeled thyroid sections stored for several years and, in addition, quantitative data was derived from 3H-labeled methacrylate sections stored from 21 days to 1 year. With the three emulsions under study, the background fog remains low under both exposure conditions at 4 degrees C for as long as several years duration. Using L4 emulsion, similar high grain densities are obtained in air and helium, and therefore, the latent images in L4 emulsion remain stable in the presence of oxygen. In the case of NTE and NR-H2 emulsions, as the exposure time increases, substantially lower reaction intensities are observed in air than in helium. This difference in reaction intensity is evident by 3 weeks with NTE and after 4 weeks with NR-H2. Hence, there is fading of the latent images in the latter emulsions in the presence of oxygen. It is concluded that reliable results may be obtained with the L4 emulsion by exposure of radioautographs in dry air, whereas with the NR-H2 and NTE emulsions, exposure should be in an oxygen-free medium, such as is provided by a dry helium atmosphere.     

Evaluation of Dust Palliatives for Unpaved Roads in Arid Climates

An evaluation of commercial and experimental dust palliatives was conducted to determine their effectiveness for mitigating fugitive dust on roads in arid climates. Several types of chemicals were tested including polymer emulsions, lignosulfonates, chloride salts, synthetic fluids, an asphalt emulsion, a polysaccharide solution, a polyacrylamide, and a guar gum. Each product was placed in an individual test section at a rate of 3.8?L/m2 using an admix construction method (grade/spray/till/compact/spray). Fourteen test sections were constructed and observed at 30-day intervals to monitor product performance. Data from both stationary and mobile particle collectors were analyzed to determine the ability of each product to suppress dust for extended periods. Several products are recommended for use on roads in arid climates as a result of this evaluation.     

Antibody mediated lung targeting of long-circulating emulsions

Monoclonal antibody 34A, which specifically binds to a surface glycoprotein (thrombomodulin) of the pulmonary endothelial cell surface in mice, has been conjugated to the surface of long-circulating emulsions composed of Castor oil, phosphatidylcholine and polyethylene glycol coupled to distearoylphosphatidyl-ethanolamine. These antibody-containing emulsions were found capable of binding to the lung when injected into mice through the tail vein. The level of lung accumulation of these emulsions depends on the amount of antibodies conjugated to the surface of the emulsions. With an input antibody to lipid ratio of 2:1 (w/w), 30% injected emulsions were found in the lung 30 minutes after administration. Such high level accumulation can be blocked by co-administration of free 34A antibody, indicating that the binding is specific and 34A antibody mediated. Kinetic studies showed that emulsion targeting to the lung was very rapid. Five minutes after tail vein injection, the total amount of emulsion found in the lung was the highest among the time points examined, indicating the completion of lung binding. However, about 50% of the initially bound emulsions remained bound for more than 4 hours. These results indicate that the targeted drug delivery using oil-in-water emulsions could be very useful to enhance the therapeutic efficacy of lipophilic drugs.     

Solubilization and stabilization of an anti-HIV thiocarbamate, NSC 629243, for parenteral delivery, using extemporaneous emulsions

The O-alkyl-N-aryl thiocarbamate, I, (2-chloro-5-[[(1-methyl-ethoxy)thioxomethyl]amino]benzoic acid, 1-methylethylester, NSC 629243, also known as Uniroyal Jr.) is an experimental anti-HIV drug with very low water solubility (1.5 micrograms/mL). Early clinical studies required an injectable solution at approximately 15 mg/mL, representing a solubility increase of approximately 10(4)-fold. Adequate solubilization of this hydrophobic drug was achieved in 20% lipid emulsions. Extemporaneous emulsions were prepared by adding a concentrated drug solution to a commercially available parenteral emulsion. Various methods of preparation to minimize drug precipitation during its addition and enhance redissolution of precipitated drug were evaluated. The stability and mechanism(s) of decomposition of NSC 629243 in both 20% lipid emulsions and in natural oil vehicles were examined. In lipid emulsions, the shelf life at 25 degrees C varied from 1 to > 10 weeks, depending on the extent to which air was excluded from the preparation. The shelf life of 50 mg/mL solutions in natural oils at 25 degrees C varied from < 1 to > 100 days depending on the oil and its supplier. A qualitative correlation was found between the initial rate of oxidation and the peroxide concentration in the oil. The primary degradation product in both systems was shown to be a disulfide dimer, II, formed via oxidation. Oxidation was inhibited by vacuum-sealing of emulsion formulations or incorporation of an oil-soluble thiol, thioglycolic acid (TGA), into oil formulations. TGA may inhibit oxidation by consuming free radicals or peroxide initiators or by reacting with the disulfide, II, to regenerate the starting drug.     

Controlled release of insect sex pheromones from paraffin wax and emulsions

Paraffin wax and aqueous paraffin emulsions can be used as controlled release carriers for insect sex pheromones for mating disruption of orchard pests. Paraffin can be applied at ambient temperature as an aqueous emulsion, adheres to tree bark or foliage, releases pheromone for an extended period of time, and will slowly erode from bark and biodegrade in soil. Pheromone emulsions can be applied with simple spray equipment. Pheromone release-rates from paraffin were measured in laboratory flow-cell experiments. Pheromone was trapped from an air stream with an adsorbent, eluted periodically, and quantified by gas chromatography. Pheromone release from paraffin was partition-controlled, providing a constant (zero-order) release rate. A typical paraffin emulsion consisted of 30% paraffin, 4% pheromone, 4% soy oil, 1% vitamin E, 2% emulsifier, and the balance water. Soy oil and vitamin E acted as volatility suppressants. A constant release of oriental fruit moth pheromone from paraffin emulsions was observed in the laboratory for more than 100 days at 27 degreesC, with release-rates ranging from 0.4 to 2 mg/day, depending on the concentration and surface area of the dried emulsion. The use of paraffin emulsions is a viable method for direct application of insect pheromones for mating disruption. Sprayable formulations can be designed to release insect pheromones to the environment at a rate necessary for insect control by mating disruption. At temperatures below 38 degreesC, zero-order release was observed. At 38 degreesC and higher, pheromone oxidation occurred. A partition-controlled release mechanism was supported by a zero-order pheromone release-rate, low air/wax partition coefficients, and pheromone solubility in paraffin.     

Studies on experimental adjuvanted influenza vaccines: comparison of immune stimulating complexes (Iscoms) and oil-in-water vaccines

Detergent-disrupted influenza virus vaccines, formulated as Iscoms, or oil-in-water (o/w) emulsions, were administered parenterally to mice and evaluated for immunogenicity and protective efficacy. Both formulations enhanced both primary and secondary serum antibody responses. The magnitude of these responses with o/w emulsions was further enhanced by the addition of the non-ionic block copolymer L121 in the emulsion. Four weeks after primary immunization, mice were challenged by exposure to an aerosol containing infectious virus. Resistance to challenge in terms of survival rate and weight change correlated well with serum antibody titre for all formulations. Two major differences were observed between the adjuvant formulations. Iscom vaccines, formulated with Quil-A or the less toxic Quillaia saponin preparation Iscoprep 703, induced specific cytotoxic T-lymphocyte responses, whereas the o/w-based vaccines did not. In addition, dose-site reactivity studies in sheep showed that Iscom vaccines were less reactive than o/w-based vaccines, the degree of reactivity of the latter increasing sharply with increasing L121 concentration. On the basis of these studies, Iscoms were chosen for development as a potential adjuvant for human influenza vaccines.     

Advanced soft magnetic composite materials for AC applications with reduced iron losses

Achieving high density with soft magnetic composite (SMC) materials requires compaction pressures exceeding 700?MPa; resulting in significant work hardening of the iron powder particles, increasing the DC magnetic coercive force along with a corresponding increase in the hysteresis loss portion of the total core loss. Annealing the as-compacted component at temperatures at or above 650°C reduces the coercive DC force and tends to decrease the AC core losses provided that the insulation layer is stable during the annealing cycle. Detailed in this paper are preliminary results utilising a novel electrically insulating inorganic coating applied to iron particles targeting fabrication of SMCs for low to medium frequency applications. This novel coating uniformly covers the iron powder and can withstand a curing temperature ≥650°C (≥1200°F). Various curing temperatures and processing conditions were evaluated and will be discussed in terms of mechanical properties as well as magnetic performance. This new material will be compared to the existing high density SMC grade that was cured at 450°C (932°F).     

Contribution of Traffic-Generated Nonexhaust PAHs, Elemental Carbon, and Organic Carbon Emission to Air and Urban Runoff Pollution

Emissions of polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), organic carbon (OC), and size distributions of particulate matter from summer tire-concrete road interaction were studied. Based on particle size distribution, particles were categorized in three groups: (1) PM10?(0.02%); (2) PM10–100?(44.20%); and (3) PM100–2,000?(55.78%). The emission factor for total of four PAHs [fluoranthene, phenenthrene, pyrene, and benzo(ghi)perylene] was estimated as 378?ng?tire?1?km?1 for small cars (engine displacement volume ? 1,000?cm3; load ? 170?kg?tire?1). Out of eight PAHS analyzed in particles (all sizes), the main PAH compounds were pyrene (54%) and benzo(ghi)perylene (21%). Emission factors for EC and OC were 1.46 and 2.37?mg?tire?1?km?1.     

Sintering and aging behaviours of Al4CuXMg PM alloy

Sintering and aging behaviours of Al–Cu–Mg powder metallurgy (PM) alloy produced from elemental powders were examined. After evaluating results from thermal analysis, tests were carried out on Al–4Cu alloys with magnesium contents of 0.5, 1 and 2?wt-% and it was found that additions of 1?wt-% Mg was most effective for enhancing the transverse rupture strength (TRS) of the Al–Cu PM alloys for both as sintered and after a heat-treatment conditions. Grain size reduction in the range of 14–45% was achieved by adding magnesium into Al–Cu system. Analyses showed that produced alloys were composed of Al, Al₂Cu, Al₂CuMg and Al₇Cu₂Fe phases. Differential scanning calorimeter and dilatometer analyses revealed that alloys show swelling behaviour after the eutectic melting reaction at 548°C and swelling rates increasing as a function of magnesium content. Both high hardness value (120 HB) and TRS (650?MPa) were achieved via aging of Al4Cu1Mg alloy for 24 hours.     

Slippage Failure of a New Hot-Mix Asphalt Overlay

A premature pavement overlay failure had occurred only 1 day after it was opened to traffic. Crescent-shaped cracks were intermittently spread over a section about 3 mi in length. Dynamic cone penetrometer results demonstrated that the slippage cracks were not linked to weak base or subgrade. Loss of overlays on structurally sound pavements due to poor bonding is an expensive error. A tack coat is considered a simple, relatively inexpensive, yet essential step in the pavement construction process. It is theorized that the ineffective bonding due to poor quality tack coat and/or inappropriate application rate is the primary factor that led to the slippage cracks. Other contributing factors include low asphalt content and high aging ratio that reduced the effectiveness of the bond. The aging ratios exceed the maximum allowable 3.5 specified. Based the investigation results, the contractor did remove and replace the top 50 mm hot-mix asphalt (HMA) overlay at his own expense. Although selection of proper tack coat materials and quantities is essential, there is a lack of proper construction quality control and quality assurance procedure to ensure appropriate surface preparation prior to application of a HMA overlay.     

Boron Removal via Formation of Magnesium Silicate Solids during Precipitative Softening

Precipitative softening is an option to remove silicon and boron from natural waters. Silicon was removed from hard waters by precipitative softening when the molar ratio of Mg:Si was less than 6:1 by the formation of an amorphous magnesium silicate. This solid had an apparent solubility product constant of 10?25.66 and was stoichiometrically similar to the mineral forsterite, Mg2SiO4. Boron removal was consistent with sorption to this amorphous magnesium silicate and could be roughly described by a Freundlich isotherm: Bsorb/Mg2SiO4(s) = 21×Bsol0.51.     

Effect of the conditions of sintering of sodium-reduced tantalum powders on their characteristics

The effect of the granulation and heat treatment of sodium-reduced tantalum powders with a specific surface area of 2.5–3.6 m²/g on the bulk density, the powder flow time, and the specific surface area of the powders and the specific capacitance of the anodes made of them is studied. It is shown that heat treatment of a granulated powder in vacuum at 1100°C or in a mixture with magnesium at 800°C makes it possible to achieve the required powder flow time.     

耐火材料转炉渣侵蚀机理的研究

研究结果表明,渣中的Ｆｅ３Ｏ４溶透进耐火砖内的深度不大,但是使砖体内部发生了质的变化。硅酸盐相有较强的渗透进耐火砖内部的能力,并且在铁昌石和镁尖晶石之间形成固溶体,因此降低了固体材料之间的直接结合能力。硅酸盐相和Ｆ３Ｏ４相的渗透和反应是影响耐火材料寿命的主要因素之一。     

The effect of FeS film on the surface of iron powder particles on mechanical properties and fracture of Fe–Cu–C alloys

This article provides a new kind of P/M processing by designing thin-layered FeS film coated on the surface of iron powder particles for preparing high density Fe–Cu–C materials. Experimental results showed that FeS lubricating coating on the surface of iron powder particles was significant as a means of reducing friction in the pressing process of Fe–Cu–C alloys. After being pressed, the green density increased from 7.18 to 7.42?g?cm^?3. The sintered density increased from 7.10 to 7.37?g?cm^?3. In the sintering process, the FeS was liquid, and useful in purifying particle surface and strengthening grain boundaries to improve the mechanical properties. The hardness and tensile strength of the Fe–2.0Cu–0.9C–0.5FeS₂ material were 80.5 HRB and 590?MPa. Analysis of fracture showed the main fracture was transgranular fracture. And FeS spherical particles gathered in the pores of the Fe–Cu–C alloys.     

Kinetics of the dissolution of zinc-magnesium ferrites in sulphuric acid solutions related to zinc leach processes

The presence of sparingly soluble zinc and magnesium ferrites in roasted zinc concentrates can cause problems during leaching. This study aimed at the determination of the dissolution kinetics of zinc ferrite-magnesium ferrite solid solutions. The investigations have been performed for the (Zn_1?xMg_x)Fe₂O₄ powder specimens (x = 0, 0.25, 0.50, 0.75 and 1) in solutions of 100–200 g/l H₂SO₄ at 323–363 K. Dissolution of all specimens has been found to be chemically controlled and homothetic, being described by the “unreacted-core shrinking” model. The dissolution rate constant of zinc ferrite was about seven times higher than that of magnesium ferrite (e.g. 3.83·10^?6 against 0.53·10^?6 mol/m²s in 100 g/l H₂SO₄ at 363 K). The relation between rate constant and the x value was not linear. The activation energy was not dependent on the x value and amounted to ca. 75 kJ/mol. The results have important relevance to the “magnesium problem” often experienced in roach-leach processes in hydrometallurgy.     

Characteristics and printability of K417G nickel-base alloy powder prepared by VIGA method

Nickel-based K417G superalloy powder is the main material used in laser additive manufacturing (LAM) of aerospace engine turbine blades. In this study, K417G powder was prepared by the vacuum induction melting gas atomisation method (VIGA). Powder characteristics and microstructure were measured, and the properties of fabricated samples were studied. The results show that the powder mean particle size D₅₀ was 74?μm, flowability was 16.6?s/50?g, apparent density was 4.78?g?cm^–3, and the oxygen content of the powder was 0.015%. Powder and LAM sample microstructure consisted of γ, γ′, and carbide. The average microhardness was 410?HV, tensile strength was 1080?MPa, yield strength was 828?MPa and elongation was 13.52%. K417G superalloy powder prepared by VIGA method has potential for application in laser additive manufacturing.     

Urban Particle Capture in Bioretention Media. I: Laboratory and Field Studies

Bioretention is a novel stormwater best-management practice that uses a mixture of soil/sand/mulch as adsorptive filtration media that can capture both urban particulates and dissolved pollutants while promoting infiltration. This study conducted a series of laboratory column experiments and field observations, which showed that: (1) bioretention media stratification occurs with runoff percolation due to particulate deposition; (2) bioretention filter media are clogging limited, instead of breakthrough limited; and (3) both depth filtration and cake filtration significantly contribute to urban particle capture. Because of the fine size of bioretention media, incoming suspended solids cannot significantly penetrate below 5–10?cm of the media in the column tests and approximately 20?cm in the monitored field facility. Bioretention filters under intermittent flow conditions exhibited higher solids loading capacity (in kg/m2) before clogging than under continuous flow conditions. The clay components in incoming total suspended solids assume critical responsibility for bioretention media clogging. The media resistance due to solids deposition was estimated through Darcy’s law. The hydraulic conductivity of two media types decreased from 54±23 and 72±46?cm/h to less than 10?cm/h due to particle capture. Experimental results suggest that a 20-cm media depth is sufficient for bioretention design and maintenance procedures (media replacement) for runoff particle capture.