Stabilization and solidification of hydrocarbon‐contaminated soils in concrete

This article describes an experimental program developed to investigate the potential for using hydrocarbon‐contaminated soils as a fine aggregate replacement in concrete. Five different contaminated soil types with a total petroleum hydrocarbon content of less than 1% were investigated. For each soil type, three concrete mixtures were obtained by replacing sand with contaminated soils (10, 20, and 40% replacement ratio). The resulting concrete was tested for setting times, compression strength, flexural strength, durability, and teachability of benzene to water.

The results indicate that the addition of hydrocarbon‐contaminated soil adversely affects the strength of concrete. The strength reduction at each soil replacement level depends on contamination concentration, contaminant type, and soil type. The durability of the tested concrete is comparable to normal concrete. For all five soils at a 40% replacement ratio, the leachability of benzene was nondetectable after 24 h and after 10 d. After testing the leachability of artificially contaminated soils (0.5 and 3% neat benzene contamination) for 24 h, it was found that the leaching of benzene increases with the percentage of contamination. However, the fraction of benzene that leached was about 95% lower than the values for loose soils.     

Fracture resistance of maxillary complete dentures subjected to long-term water immersion

doi: 10.1111/j.1741‐2358.2012.00616.x Fracture resistance of maxillary complete dentures subjected to long‐term water immersion Objective: This study investigated the fracture resistance of maxillary acrylic resin complete dentures subjected to long‐term water immersion. Materials and Methods: Maxillary acrylic resin complete dentures were fabricated from five denture base resins. Half of the dentures were stored in water for 50 h, and the other half were kept in water for 180 days before testing. Ten specimens were fabricated per group. The flexural load at the proportional limit (FL‐PL) of the dentures was tested. Results: A two‐way anova revealed a significant difference in FL‐PL because of the denture base material variable. There were no significant differences in FL‐PL because of the effect of water immersion and the interaction between the effect of water immersion and the denture base material. The FL‐PLs of the dentures fabricated with the two conventional heat‐processed resins, the pour‐type autopolymerizing resin and the microwave energy‐processed resin were not significantly different from each other; they were significantly higher than the light‐activated resin in regard to their FL‐PL. Conclusion: The FL‐PLs of the maxillary acrylic resin complete dentures did not change after long‐tern water immersion, and the FL‐PL of the denture fabricated from the light‐activated resin was lower than those of the other materials.     

Quasi-linear viscoelastic properties of costal cartilage using atomic force microscopy

Costal cartilage (CC) is one of the load-bearing tissues of the rib cage. Literature on material characterisation of the CC is limited. Atomic force microscopy (AFM) has been extremely successful in characterising the elastic properties of soft biomaterials such as articular cartilage and hydrogels, which are often the material of choice for cartilage models. But AFM data on CC are absent in the literature. In this study, AFM indentations using spherical beaded tips were performed on human CC to isolate the mechanical properties. A novel method was developed for modelling the relaxation indentation experiments based on Fung's quasi-linear viscoelasticity and a continuous relaxation spectrum. This particular model has been popular for uniaxial compression test data analysis. Using the model, the mean Young's modulus of CC was found to be about 2.17, 4.11 and 5.49 MPa for three specimens. A large variation of modulus was observed over the tissue. Also, the modulus values decreased with distance from the costochondral junction.     

Valorization of Foundry Sand in Clay Bricks at Industrial Scale

In this article, foundry sand as waste material has been valorized in ceramic brick manufacturing at industrial scale. The employment of a waste coming from one industry as an input for another is one of the key concepts of industrial ecology. To study the environmental behavior of the ceramic bodies in different life cycle stages, three leaching tests have been developed. We used an EN 12457 equilibrium leaching test with distilled water and a Wastewater Technology Centre acid neutralization capacity (WTC‐ANC) leaching test with different acidic leachates to carry out the environmental evaluation under different granular scenarios to ascertain the possibilities of the reuse or disposal of this granular material at the end of its useful life (end‐of‐life stage). Finally, we used a NEN 7345 diffusion leaching test for construction materials, with the aim of studying the environmental assessment at the use stage. Regulated pollutants in both stages have been evaluated. Furthermore, other soluble salts have been analyzed because they are closely related to the efflorescence phenomenon in bricks. Results indicate that core and green sand from the foundry industry can be used to replace clay content in construction materials, and that these foundry‐sand‐based ceramics improve some soluble salt results. Despite this fact, at the end‐of‐life stage in an inert waste landfill, lead, arsenic and chromium can be an environmental problem, both for commercial bricks and for foundry‐sand‐based bricks. This work can contribute to the determination of viability of sustainable processes of brick manufacturing that use foundry wastes as raw materials.     

Methodology for using contaminated soil leachability testing to determine soil cleanup levels at contaminated petroleum underground storage tank (UST) sites

The costs of environmental remediation at leaking petroleum underground storage tank (UST) sites are influenced significantly by soil cleanup levels. The use of conservative generic soil cleanup levels may be inappropriate at some sites contaminated by leaking petroleum USTs. At many contaminated sites, a primary objective of site remediation is long‐term protection of water resources (e.g., groundwater) from pollution. Leaching of pollutants from residual soil contamination to groundwater is a primary consideration in establishing site‐specific soil cleanup levels at fuel‐contaminated sites. The use of laboratory soil leachability testing methods may be useful in objectively evaluating the leaching potential of contaminants from residual soil contamination and estimating potential groundwater impacts. Developing soil cleanup levels that are protective of water resources must include a technically sound integration of site‐specific soil leachability data and contaminant attenuation factors. Evaluation of the leaching potentials of soil contaminants may also provide essential supplementary information for other site characterization methods that may be used to evaluate risks to human health. Contaminant leachability testing of soils may provide a cost‐effective and technically based method for determining soil cleanup levels that are protective of groundwater resources at contaminated petroleum UST sites.     

Quasi-linear viscoelastic properties of costal cartilage using atomic force microscopy

Costal cartilage (CC) is one of the load-bearing tissues of the rib cage. Literature on material characterisation of the CC is limited. Atomic force microscopy (AFM) has been extremely successful in characterising the elastic properties of soft biomaterials such as articular cartilage and hydrogels, which are often the material of choice for cartilage models. But AFM data on CC are absent in the literature. In this study, AFM indentations using spherical beaded tips were performed on human CC to isolate the mechanical properties. A novel method was developed for modelling the relaxation indentation experiments based on Fung's quasi-linear viscoelasticity and a continuous relaxation spectrum. This particular model has been popular for uniaxial compression test data analysis. Using the model, the mean Young's modulus of CC was found to be about 2.17, 4.11 and 5.49?MPa for three specimens. A large variation of modulus was observed over the tissue. Also, the modulus values decreased with distance from the costochondral junction.     

Influence of varnish application on a tissue conditioner: analysis of biofilm adhesion

doi:10.1111/j.1741‐2358.2009.00290.x
Influence of varnish application on a tissue conditioner: analysis of biofilm adhesion Purpose: The aim of this study was to evaluate if the use of a varnish on a tissue conditioner would affect biofilm adhesion. Background: After the surgery has been performed, before the delivery of a complete denture, it is often necessary to use materials such as tissue conditioners on the surgical wound. However, these materials present deficient physico‐mechanical properties, which allow biofilm development. Methods: Forty elderly volunteers wearing complete maxillary dentures were selected. They were randomly allocated into two groups (n = 20), G1 and G2. In both groups, a silicone‐based tissue conditioner was placed in a recess created at the base of the denture, according to the manufacturer’s guidelines. In group G1, a varnish was applied to the tissue conditioner, while in group G2, no treatment was applied. All volunteers performed daily hygiene of the prosthesis with a soft toothbrush, and toothpaste. Quantification of the mean score values of biofilm formed at different time points (baseline, 1 week and 3 weeks) was statistically analysed using anova (α = 0.05). Results: Group G2 (1.6 ± 1.2) showed the lowest mean score values of biofilm formation and there was a statistical difference between the groups (p = 0.03). The highest mean score values were found after 3 weeks (2.7 ± 1.4) and were statistically different from the other time points studied (baseline and 1 week). Conclusion: The use of a varnish had a detrimental effect on the tissue conditioner studied, allowing higher biofilm formation.     

Reducing the Leachability and Bioaccessibility of Arsenic in Soils using Supported Nano Titanium Dioxide

We herein report the development and testing of a novel material, namely activated carbon-supported nano titanium dioxide (ACTD) for the immobilization of arsenic in soil. This material, which was prepared using a sol-gel method, effectively reduced the toxicity characteristic leaching procedure (TCLP) leachability and physiologically based extraction test (PBET) bioaccessibility of As(III) in soil samples. Upon processing the soils for 56 d at an ACTD dosage of 0.25 mmol g^?1, the TCLP leachability of As(III) was reduced by 82.7–97.7%, while the bioaccessibility was lowered by 58.6–81.2%. In addition, sequential extraction resulted in an 11.5–96.0% decrease in the mobile-As(III) and the mobilizable-As(III) fractions, but an increase in the residual-As(III) fraction upon treatment with ACTD. These observations indicate that the application of ACTD could result in an 80% reduction in As(III) environmental leaching, thereby confirming that ACTD appears suitable for the treatment of arsenic-contaminated soil.     

Effects of the peracetic acid and sodium hypochlorite on the colour stability and surface roughness of the denture base acrylic resins polymerised by microwave and water bath methods

Objective: This study evaluated the surface roughness (Ra) and color stability of acrylic resin colors (Lucitone 550, QC‐20 and Vipi‐Wave) used for fabricating bases for complete, removable dentures, overdentures and prosthetic protocol after immersion in chemical disinfectants (1% sodium hypochlorite and 2% peracetic acid) for 30 and 60 minutes. Material and Methods: Sixty specimens were made of each commercial brand of resin composite, and divided into 2 groups according to the chemical disinfectants. Specimens had undergone the finishing and polishing procedures, the initial color and roughness measurements were taken (t=0), and after this, ten test specimens of each commercial brand of resin composite were immersed in sodium hypochlorite and ten in peracetic acid, for 30 and 60 minutes, with measurements being taken after each immersion period. These data were submitted to statistical analysis. Results: There was evidence of an increase in Ra after 30 minutes immersion in the disinfectants in all the resins, with QC‐20 presenting the highest Ra values, and Vipi‐Wave the lowest. After 60 minutes immersion in the disinfectants all the resins presented statistically significant color alteration. Conclusions: Disinfection with 1% sodium hypochlorite and peracetic acid altered the properties of roughness and color of the resins.     

pH effect on the mechanical performance and phase mobility of thermally processed wheat gluten-based natural polymer materials

The mechanical properties, phase composition, and molecular motions of thermally processed wheat gluten- (WG-) based natural polymer materials were studied by mechanical testing, dynamic mechanical analysis (DMA), and solid-state NMR spectroscopy. The performance of the materials was mainly determined by the denaturization and cross-linking occurring in the thermal processing and the nature or amount of plasticizers used. The pH effect also played an important role in the materials when water was used as the only plasticizer (WG-w). Alkaline conditions modified the chemical structure of WG, possibly via deamidation; enhanced the thermal cross-linking of WG macromolecules to form a more stable aggregation structure; and promoted intermolecular interactions between water and all components in WG (proteins, starch, and lipid), resulting in a strong adhesion among different components and phases. The saponification of lipid under alkaline conditions also enhanced the hydrophilicity of lipid and the miscibility among lipid, water, and WG components. However, when glycerol was used with water as a plasticizer (WG-wg), the phase mobility and composition of the materials mainly depended on the content of glycerol when the water content was constant. During thermal processing under either acidic or alkaline conditions, glycerol was unlikely to thermally cross-link with WG as suggested previously. The advanced mechanical performance of the WG-wg materials was attributed to the nature of hydrogen-bonding interactions between glycerol and WG components in the materials. This caused the whole material to behave like a strengthened "cross-linked" structure at room temperature due to the low mobility of glycerol. The pH effect on phase mobility and compositions of WG-wg systems was not as significant as that for WG-w materials.     

Experimental Study of Mobility and Kinetic Characterization of Trace Elements in Contaminated Sediments from a River Basin in Northern Peru

In the Jequetepeque basin (Peru), gold extraction activity has been performed in the last decades, leading to a release of metals and metalloids into the environment. Sediment samples were taken in the vicinity of two mines and analyzed. Extraction of metals and metalloids from sediments was carried out using single extraction procedures, acidic (HNO₃), and complexation (EDTA) leaching, in order to determine the mobility of trace elements. Results indicated that acidic extraction at low pH values increased the leachability of trace elements. EDTA showed a higher bioavailability of metals in sediments than acidic extraction under similar pH conditions because of its greater leaching capacity. This is an important issue in view of risk assessment analysis. The highest extractability was observed for Cd in all sediments with up to 90% of extraction after 1 h. The mobility index analysis indicated that faster kinetic leachability of some trace elements leads to a higher mobility in sediments, especially those near the active gold extraction mine. The ecological risk assessment suggested that the four river sediments were at high and very high risk levels, indicating that sediment contamination is an issue of environmental concern in the Jequetepeque basin of northern Peru.     

Bacterial leaching of two Swedish zinc sulfide ores

Abstract: Two Swedish zinc sulfide ores, from Saxberget (S-ore) and Kristineberg (K-ore), respectively, were compared for bacterial leachability with respect to grain size, and additions of ammonia, iron and phosphate. 87 days of column leaching resulted in 2.4–3.2 g Zn/I in solution and 1.5–1.9 g Cu/I from the K-ore and 1.2–5.3 g Zn/l and 0–0.3 g Cu/l from the S-ore. The highest values were achieved for grain sizes between 16 and 64 mm. Ammonium showed a stimulating effect on bacterial leaching, increasing leached Zn in the K-ore from 27% to 35% and from 7% up to 70% Zn in the S-ore after 53 days of batch leaching. Phosphate additions showed negative effects. Iron additions had a positive effect for the K-ore, increasing the leaching from 48% to 78% Zn at an addition of 6 mg Fe²⁺.     

Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation

doi: 10.1111/j.1741‐2358.2011.00484.x
Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation Background: This study evaluated the effect of disinfection by immersion and microwave irradiation on the roughness of one denture base resin (Lucitone‐L) and five relining materials, three hard (Tokuyama Rebase II‐TR, New Truliner‐NT, Ufigel Hard‐UH) and two resilient (Trusoft‐T, Sofreliner‐S). Methods: Fifty specimens were made and divided into groups: CL2 specimens were brushed with 4% chlorhexidine (1 min), immersed in the same solution (10 min) and immersed in water (3 min); MW2 specimens were immersed in water and microwave irradiated (650W; 6 min); CL2 and MW2 specimens were disinfected twice; CL7 and MW7 specimens were submitted to seven cycles using chlorhexidine or microwave irradiation, respectively; W specimens were not disinfected and remained in water (37°C; 7 days). Results: Results were statistically analysed (p = 0.05) and revealed that, at baseline, the highest mean value was observed for T (p < 0.001). Material NT showed increase in roughness after the first (p = 0.003), second (p = 0.001), seventh (p = 0.000) cycles of microwave disinfection and after 7 days of immersion in water (p = 0.033). Conclusions: Resilient liner S presented significant increase in roughness after the second cycle of disinfection with chlorhexidine (p = 0.003). Material T exhibited significantly decreased roughness in group W (p = 0.010), while microwaving produced severe alterations on its surface.     

Water-induced hydrophobicity of soy protein materials containing 2,2-diphenyl-2-hydroxyethanoic acid

Biodegradable soy protein isolate (SPI), containing 2,2-diphenyl-2-hydroxyethanoic acid, films (SB) were successfully prepared with bis-(2-hydroxyethyl)sulfide as a plasticizer by compression molding at 155 degrees C and 15 MPa. By immersing the SB in distilled water for 26 h, we prepared the films (coded as SB-WM) having good water resistance. The films were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical thermal analysis, and tensile testing to evaluate their structure and properties. Moreover, the surface of the SB-WM films was analyzed by X-ray photoelectron spectroscopy and contact angle measurement. SB-WM films exhibited significantly higher contact angle than SB. The results revealed that a lotus-like nanoscale structure was created in SB-WM films, with increased hydrophobicity, through the process of the solvent-induced microphase separation during the immersion in water. More stable compound diphenylhydroxymethane could form from 2,2-diphenyl-2-hydroxyethanoic acid of SB in water, leading to the hydrophobicity of the SB-WM materials. A "green" and easy method for fabricating hydrophobic materials from soy protein has been provided in this work.     

Effect of carbide sludge (lime) on bioavailability and leachability of heavy metals during rotary drum composting of water hyacinth

Abstract

The bioavailability and leachability of heavy metals play a major role in the toxicity of heavy metals in the compost applied for soil conditioning. A rotary drum composter was used for the study of heavy metal bioavailability and leachability during water hyacinth composting with a mixture of cattle manure, sawdust and lime. Lime was added in 1, 2 and 3% to the mixture of water hyacinth, cattle manure and sawdust at a ratio of 6:3:1 respectively. Influences of physico-chemical parameters on heavy metal bioavailability and leachability were studied during the process. The bioavailability of heavy metals solubility and diethylene triamine penta-acetic acid extractability was examined. The toxicity characteristics leaching procedure (TCLP) test was performed for assessing the hazardous properties of compost. The nutrients and the total concentration of heavy metals were increased during the composting process. The lime was very effective in reducing water solubility, plant availability and leachability of the selected heavy metals (Zn, Cu, Mn, Fe, Ni, Pb, Cd and Cr) during the process. The addition of lime provided a buffer against the decrease in pH and a sufficient amount of Ca that would improve the metabolic activity during composting. The addition of an excess amount of lime slowed the metabolic activity of the microbes due to its high alkalinity. The TCLP test confirms that the heavy metals concentrations in the control and in the lime-amended compost were below the threshold limits.     

Effect of antifungal gels incorporated into a tissue conditioning material on the growth of Candida albicans

doi:10.1111/j.1741‐2358.2009.00337.x
Effect of antifungal gels incorporated into a tissue conditioning material on the growth of Candida albicans Objective: The aim of this study was to examine the effectiveness of antifungal gels incorporated into a tissue conditioner which inhibits the growth of Candida albicans in vitro. Background: The release of drugs from relining materials has been demonstrated earlier. However, the incorporation of antifungal agents in gel form has not yet been studied. Materials and methods: Visco‐gel^® tissue conditioner was prepared with chlorhexidine digluconate and miconazole in gel form in a concentration of 5, 10, 15, 20 and 25% by volume. Sample discs were prepared and placed on Sabouraud Dextrose Agar (SDA) plates which had been previously inoculated with C. albicans, and incubated aerobically at 37°C. To investigate antifungal activity over time, Visco‐gel discs containing 20%v/v miconazole were prepared and immersed in water for different time periods before being placed on SDA plates inoculated with C. albicans. Results: Chlorhexidine digluconate gel added to tissue conditioner had no inhibition effect on the growth of C. albicans. Incorporation of miconazole gave a dose‐related inhibitory effect on candidal growth. Immersion of the discs in water showed an inverse relationship between time of immersion and degree of inhibition. Conclusion: Miconazole added in gel form to Visco‐gel^® had an inhibitory effect on the growth of C. albicans in vitro.     

Two‐Step Activated Carbon Cloth with Oxygen‐Rich Functional Groups as a High‐Performance Additive‐Free Air Electrode for Flexible Zinc–Air Batteries

A flexible air electrode (FAE) with both high oxygen electrocatalytic activity and excellent flexibility is the key to the performance of various flexible devices, such as Zn–air batteries. A facile two‐step method, mild acid oxidation followed by air calcination that directly activates commercial carbon cloth (CC) to generate uniform nanoporous and super hydrophilic surface structures with optimized oxygen‐rich functional groups and an enhanced surface area, is presented here. Impressively, this two‐step activated CC (CC‐AC) exhibits superior oxygen electrocatalytic activity and durability, outperforming the oxygen‐doped carbon materials reported to date. Especially, CC‐AC delivers an oxygen evolution reaction (OER) overpotential of 360 mV at 10 mA cm^?2 in 1 m KOH, which is among the best performances of metal‐free OER electrocatalysts. The practical application of CC‐AC is presented via its use as an FAE in a flexible rechargeable Zn–air battery. The bendable battery achieves a high open circuit voltage of 1.37 V, a remarkable peak power density of 52.3 mW cm^?3 at 77.5 mA cm^?3, good cycling performance with a small charge–discharge voltage gap of 0.98 V and high flexibility. This study provides a new approach to the design and construction of high‐performance self‐supported metal‐free electrodes.     

Feasibility study of using the dispersion of surface acoustic wave impulse for viscoelasticity characterization in tissue mimicking phantoms

The aim of this study was to investigate the feasibility of utilizing the phase velocity dispersion of impulse surface acoustic wave (SAW) for viscoelasticity characterization of soft materials. The focused ultrasound transducer and the phase‐sensitive optical coherence tomography were applied as the impulse SAW inducer and tracker, respectively. Three types of liquid‐paraffin‐based cream‐in‐agar phantoms were tested. Phase velocity dispersion curve was extracted using a Fourier transform‐based phase velocity analysis algorithm. Viscoelastic parameters were obtained by fitting the dispersion curve of SAW into Rayleigh wave dispersion equation. The estimated viscoelasticity was compared with that from spherical indenter, ramp‐hold relaxation testing for validation. Both results show an increasing trend in the elasticity and decreasing trend in the viscosity with the concentration of liquid‐paraffin‐based cream increasing in the samples. The proposed method has the capability of evaluating the viscoelastic properties of homogeneous soft tissue. By combining viscoelastic parameters estimated from the proposed method, the dispersive SAW‐impulse‐based viscosity‐compensated elastography could be further developed.      

Estimating Materials Stocked by Land‐Use Type in Historic Urban Buildings Using Spatio‐Temporal Analytical Tools

The construction industry is an important contributor to urban economic development and consumes large volumes of building material that are stocked in cities over long periods. Those stocked spaces store valuable materials that may be available for recovery in the future. Thus quantifying the urban building stock is important for managing construction materials across the building life cycle. This article develops a new approach to urban building material stock analysis (MSA) using land‐use heuristics. Our objective is to characterize buildings to understand materials stocked in place by: (1) developing, validating, and testing a new method for characterizing building stock by land‐use type and (2) quantifying building stock and determining material fractions. We conduct a spatial MSA to quantify materials within a 2.6‐square‐kilometer section of Philadelphia from 2004 to 2012. Data were collected for buildings classified by land‐use type from many sources to create maps of material stock and spatial material intensity. In the spatial MSA, the land‐use type that returned the largest footprint (by percentage) and greatest (number) of buildings were civic/institutional (42%; 147) and residential (23%; 275), respectively. The model was validated for total floor space and the absolute overall error (n = 46; 20%) in 2004 and (n = 47; 24%) in 2012. Typically, commercial and residential land‐use types returned the lowest overall error and weighted error. We present a promising alternative method for characterizing buildings in urban MSA that leverages multiple tools (geographical information systems [GIS], design codes, and building models) and test the method in historic Philadelphia.     

Hot-water treatments for control of Planococcus ficus (Homoptera: Pseudococcidae) on dormant grape cuttings

Hot-water immersions were tested for control of mealybug Planococcus ficus (Signoret), on dormant grape cuttings used for nursery stock. A range of hot-water temperatures (47-58 degrees C) were evaluated at immersion periods of 2, 5, 10, or 20 min, by using a total of 353,720 mealybugs across all treatments. A 5-min immersion at 51 degrees C is effective in killing > 99% of P. ficus. At or above this immersion period and temperature, there was no difference in mealybug stage mortality. We evaluated a commercial operation, which used a 5-min immersion in each of three water tanks: preheating (30.0 +/- 3 degrees C), hot-water (52.8 +/- 0.3 degrees C), and cooling (23 +/- 3 degrees C). The commercial procedure provided 99.8-100% mealybug control in each of three separate trials.