Open Pore Volume Research Articles

Preparation of dextran cryogels for separation processes of binary dye and pesticide mixtures from aqueous solutions

AbstractWe present mechanically strong macroporous, squeezable dextran cryogels as a column filling material for the removal and separation of binary organic dye and pesticide mixtures from aquatic medium. Dextran cryogels were prepared from aqueous solutions of dextran of various molecular weights (MWs) in the presence of 20 to 50 mol% divinyl sulfone (DVS) as a cross‐linker at −18°C. The cryogels have interconnected irregular pores of 100 μm in sizes, and exhibit 69‐84% reversible squeezability without damaging the 3D dextran network. Their total open pore volumes (6.3‐10 mL g−1), weight swelling ratios in water (1380%‐2200%), and mechanical parameters could easily be adjusted by both DVS mol% and MW of dextran. Dextran cryogel with the highest modulus (3.8 ± 0.5 MPa), compressive stress (8 ± 2 MPa) and plateau stress (0.46 ± 0.04 MPa) was obtained at 50 mol% DVS using dextran with a MW of 15 to 25 kg·mol−1. Dextran cryogels are hydrolysable at pH = 1 and 9 but stable at 7.4 independent on both the degree of cross‐linking and MW of dextran. At below 50 mol% DVS, they are blood compatible and possess slight thrombogenic effect with blood clotting index value of 98% ± 5%. They are also capable to separate binary dye and pesticide mixtures from aqueous solutions via ionic interactions.

Using PC clinker as aggregate-enhancing concrete properties by improving ITZ microstructure

The interfacial transition zone (ITZ) in a concrete microstructure is a region of high porosity and low binding materials at the interface of cement paste and aggregate that causes significant reduction in compressive and flexural strengths and considerable increase in permeability of the concrete. Extensive research activities have been devoted to reduction of the ITZ, to avoid its negative effects on concrete properties. This research introduces reactive aggregate concrete (RAC), formed by partial replacement of natural aggregate with Portland cement (PC) clinker of the same size as a reactive aggregate in the concrete mix to reduce the ITZ and improve the concrete properties. After determining the optimum replacement level based on 28 and 60 d compressive strengths, the developed RAC was characterised by measuring its workability, setting time, compressive and flexural strengths, for varying age, water absorption, open-pore volume and chloride penetration depth. Microstructural studies of the ITZ were also performed using scanning electron microscopy. In all measurements, normal concrete was also considered for comparison purposes. The results confirm 121% and 33% enhancement in 7 and 90 d compressive strengths accompanied with 53, 19 and 22·4% reductions in 28 d chloride penetration depth, open-pore volume and water absorption, respectively.

Generalized variables for both porous and ordered mesoporous materials

This work is a continuation of our previously published work (Titelman in J Porous Mater 19:1–13, 2012), where generalized variables for the synthesis of porous materials were proposed: processing X and structural Y. X represents the route of the entire production process and covers the complete set of individual variables, both quantitative and qualitative. This paper proposes a concept of equivalent X-s, that is, routes leading to equal values of the property of interest. Examples of equivalent X are given. The most economical route can be chosen. Y = Vw/Vp (the ratio of the apparent volume of the walls to the total volume of open pores) is the structural parameter of the ordered mesoporous materials (OMMs), more sensitive than the wall thickness. For OMMs a formula is proposed for estimating Vw; this is the product of the total surface area SBET and the wall thickness t. Now the Y covers all parameters of OMM. Excluding the volume Vsk of the skeleton from Vw, we obtain the volume Viw of inaccessible intrawall pores; the size effect (Vradman et al. in Microporous Mesoporous Mater 93:313–317, 2006) on Viw was discovered. The specific length of the adsorbate body Lv proposed in Titelman (2012) is supplemented by the length of the surface area of the adsorbent Ls and the equation relating the hydraulic diameter Dh to the average pore diameter Dp is obtained. The known Dh = 4Vp/SBET is equal to Dp, only if Lv = Ls. Dh is considered as a diameter of pores with smooth walls, and Ls/Lv—as a roughness factor. Application of the proposed parameters gives a new insight of many published results. Presentation of equivalent processing variables (routs); roughness factor as result of new derivation of hydraulic pore diameter and size effect on intrawall void space.

Composition and Type of a Binder Effects on the Stainless Steel Foam Microstructure Prepared by Sponge Replication Method

Biomaterials with a porous structure are beneficial for a wide range of medical engineering applications such as filtration, bone replacement and implant development. Stainless Steel 316L (SS316L) foam has been fabricated by foam replication method at different SS316L powder composition which is 60 wt%, 65 wt%, and 70 wt%. The binders used were Polyethylene Glycol (PEG), Carboxymethyl Cellulose (CMC) and Polyvinyl Alcohol (PVA), while distilled water was used as a solvent. The effects of using different composition of SS36L powder, binders and sintering time to the SS316L foam properties was studied. The materials were mixed by using a mechanical stirrer at 250 rpm for 1 hour. Polyurethane foam (PU) which was used as a sacrificial template was dipped into the SS316L slurry until fully coated. The coated samples were then dried in a drying oven within 24 hours before being sintered in an argon gas environment at 1200°C. The samples were characterized to observe the microstructure of the SS316L foam produced. As expected, the viscosity of the SS316L slurry was increased as the SS316L composition increases. The viscosity of SS316L slurry prepared by using PVA as a binder is higher than the SS316L slurry prepared with CMC and PEG as binder. The SS316L foam produced consisted of a large volume of open and interconnected pores especially at higher SS316L composition.

Vitamin D3 Release from Traditionally and Additively Manufactured Tricalcium Phosphate Bone Tissue Engineering Scaffolds.

Bone is a randomized, complex porous network which researchers have tried to mimic within bone tissue engineering scaffolds. The objective of this study was to understand the effects of random and controlled scaffold porosity on the release kinetics of vitamin D3 to determine if a designed porous structure was comparable in effectiveness on osteoblast proliferation to the randomized essence of natural bone. In this study, porous tricalcium phosphate (TCP) scaffolds were prepared by fugitive material removal method using naphthalene and 3D printing to model random and controlled porosity, respectively. Scaffold comparison was made based on open pore volume percentage of which naphthalene scaffolds had 45.8 ± 1.5% and 3D printed scaffolds had 48.9 ± 2.5%, Comparative analysis of traditional bioceramic processing to additive manufacturing is limited especially regarding drug release kinetics. Results showed the naphthalene scaffold surface area was only 0.3% that of 3D printed scaffolds due to the lower open pore interconnectivity. This increase in surface area produced higher release of drug and osteoblast proliferation in 3D printed scaffolds comparatively. By 11days, osteoblast proliferation was enhanced by 64% from scaffolds manufactured using 3D printing compared to traditional processing. Understanding the effects of processing methods of TCP scaffolds on the release kinetics of vitamin D3 and the system effects on cells can aid in low load bearing applications for bone tissue engineering.

Production of composite clay bricks: A value-added solution to hazardous sludge through effective heavy metal fixation

The study explores utilization of hazardous battery sludge in fired clay brick production with the conjoint aim of reducing depletion of fertile clay and heavy metal fixation. Spectroscopic analysis of pulverized clay soil (PCS) and pulverized battery sludge (PBS) revealed presence of fluxing agents viz. K2O, Fe2O3, CaO, MgO, and TiO2. PBS added bricks (B0–B50%, w/w) were casted and fired in the temperature range from 950 to 1050 °C and B5 bricks (1050 °C) showed the highest compressive strength (74 N/mm2) and the lowest water absorption (2.1%). The modified bricks exhibited an improved ductile behavior and porosity restraining its deformation and/or distortion during firing and avoiding sudden failure of masonries. PBS imparted yellow coloration to bricks due to high CaO content, which can be an added benefit in decorative purposes. The bricks were tested for linear shrinkage behavior, volume of open pores, bulk density, and loss on ignition. Furthermore, the toxicity characteristic leaching procedure test confirmed an effective Pb, Cd Ni, and Zn fixation, and B20 bricks complied IS:1077:1992 class 12.5 and ASTM International.

Tungsten carbide – Titanium carbide composite preparation by arc plasma melting and its characterization

WC-TiC composite with six different values of TiC in the range 1–15 wt% was prepared by arc plasma (Ar) melting. Characterizations of the in situ melt-cast composite as well as its powder by XRD, FESM, TEM, SAED and EDS show the composite to consist of related carbide, sub-carbide and mixed carbide phases [WC, W2C, TiC, TiC0.981 /TiC1-x, TiWC2 /(Ti,W)C] besides presence of minor phases such as carbon (graphite), W, and TiO2 in traces in few cases. The composite exhibits high hardness and a maximum value of 3650 ± 75 VHN is observed in the case of WC-12 (WC+15 wt% TiC) sample. Improved hardness is attributed to the presence of phases like TiC, TiC0.981 /TiC1-x and TiWC2/(Ti,W)C. While total pore volume of open pores in the composite (measured by BET method) lies in the range 0.0002–0.0097 cm³ /g. TEM study of the microstructures shows absence of meso and macro pores in the samples. In the light of these findings, the composite may be called zero porosity material for practical usage. Young's modulus for different compositions of the composite shows significantly high values in the range of 540–703 GPa. Simultaneous improvement in hardness and Young's modulus value of the composite may be attributed both to growth of new mixed carbide phases of W and Ti as stated above and porosity free nature of the samples. The new composite has good scope for use in cast cutting tools, grinding wheels, bullet-proof vests, etc.

Mesoporous-mixed-phase of hierarchical bismuth oxychlorides nanophotocatalyst with enhanced photocatalytic application in treatment of antibiotic effluents

The mesoporous-mixed-phase of hierarchical bismuth rich-bismuth oxychlorides nanophotocatalysts were synthesized using a facile one-pot sorbitol-nitrate solution auto-combustion synthesis and without additional heat and other post-treatments. The efficacies of the sorbitol as fuel to oxidizer ratio which is called the fuel to oxidizer ratio were studied on the behaviour of combustion, type and weighted quantity of phases and other remarkable features via X-ray diffraction, field-emission scanning electron microscopy, particle size distribution, Energy-dispersive X-ray spectroscopy-Dot mapping, Brunauer-Emmett-Teller and Barrett-Joyner-Halenda and Ultraviolet–Visible diffuse reflectance spectroscopy analyses. Moreover, the solar-light-driven heterogeneous photocatalytic performance of nanophotocatalysts fabricated was evaluated in the antibiotic ofloxacin degradation as an emerging contaminant. The bismuth rich-bismuth oxychlorides synthesized with fuel ratio of 1, as the grain-like mixed-phase with an intra-heterojunction between 59% BiOCl and 41% Bi24O31Cl10 indicated the higher activity (at about 80% after 120 min irradiation) and degradation rate (0.018 min−1) as well as substantial stability after five cycles with high total open pore volume of 0.189 cm3/g, specific surface area of 93 m2/g, meso-structure of pores with average pore width of 11 nm, absorption of much light, appropriate band gap (2.69 eV), and the diminution of incorporation rate of electrons and holes. The mesoporous-mixed-phase bismuth rich-bismuth oxychlorides is a promising solar-light-driven nanophotocatalyst for organics photo-destruction.

Improvement in hydration resistance of CaO granules by addition of Zr(OH)4and Al(OH)3

AbstractImproving the hydration resistance of CaO aggregates is the key to successful application of lime‐based refractories in metallurgical industry. Additive Zr(OH)4and Al(OH)3were introduced in the preparation of CaO granules using granulation equipment and calcination method in this study. The results showed that the hydration resistance of CaO granules was improved significantly, especially for granules with 0.6 wt.% Zr(OH)4and 0.9 wt.% Al(OH)3, respectively. The shell of CaO granules was relatively dense after calcination and the volume of open pores of CaO granules decreased from 3.56 × 10−2to 1.80 × 10−2cm3/g when additive was introduced. Zr(OH)4and Al(OH)3have the opposite effect on the closed porosity of CaO granules, the closed porosity of CaO granules was decreased with Zr(OH)4addition, but increased with Al(OH)3addition.

Analogue iron ore sinter tablet structure using high resolution X-ray computed tomography

During iron ore sintering large structural changes occur as liquid is formed in the flame front. The transformation of the structure into the agglomerated product is important for its physical and metallurgical properties. To quantify the change in sinter structure, analogue sinter tablets were made under tightly controlled conditions in a rapid heating furnace. The effect of maximum temperature, partial pressure of oxygen and ore type was investigated using a factorial design methodology. The internal structure of these tablets was measured in three dimensions using high resolution X-ray computed tomography (4.5 μm voxel size), to determine the size, shape and connections of the pores. Most of the open pore volume was contained in a single continuous interconnected pore network. Analysis showed maximum temperature, ore type and the interaction between ore type and maximum temperature to have a statistically significant impact on tablet volume. A similar analysis showed maximum temperature, ore type and the interaction between maximum temperature and partial pressure of oxygen (pO2) to have a statistically significant impact on total porosity. Greater melt volumes increased the size, sphericity and total volume of pores.

INFLUENCE OF SLAGS OF BOILERS WITH CIRCULATING FLUIDIZED BED ON FROST RESISTANCE OF CONCRETE

The results of the study of the influence of slags of boilers with a circulating fluidized bed on the frost resistance of heavy concrete are presented. In the studies was used fallowing materials: Portland cement PC I-500N, sand with a grain size unit Mkr=1,05, crushed granite fraction 5-10 mm, ashes of boilers with circulating fluidized bed, hyperplasticizer "Fluid Premia-196". The research is conducted using mathematical planning of the experiment.It is proved that with the replacement of sand with ashes, frost resistance is somewhat reduced, but the hyperplasticizer contributes to the reduction of frost resistance by reducing the W/C ratio, resulting in the formation of super-fine pore structure of concrete. Fine pores in the structure of concrete compensate for stress from the process of ice formation at low ambient temperatures.The optimal flow of cement has been established in terms of frost resistance, both by full and partial replacement of sand with ash. It was also determined that the optimum should be considered the consumption of a hyperplasticizer in the amount of 1.2-1.4% of the mass of cement.The introduction of ashes in a concrete mixture leads to a decrease in the frost resistance of concrete. This phenomenon is explained by the fact that the slags have water consumption in three times higher than the amount of sand they replace, therefore they contribute to an increase in the W/C ratio. With the increase in W/C increases both the total volume of open pores, and their average size. At the same time, permeability and water absorption increase and in such concrete less reserve pores are formed. In order to increase the frost resistance of concrete, it is customary to restrict W/C depending on the conditions of concrete service. Reducing W/C is possible, as at the expense of reducing water consumption due to the application of plasticizers additives, and by increasing the cost of cement.

Bone quality evaluation of experimental osteometabolic disease in Pantanal alligators (Caiman yacare) by High Resolution Computerized Microtomography (μCT)

ABSTRACT: Computerized microtomography is the gold standard examination for the evaluation of the three-dimensional bone structure. This experiment was developed to evaluate the structure and bone quality of Caiman yacare with metabolic bone disease using high resolution computerized microtomography (μCT). The animals were distributed into four groups: G1 - hyperphosphatemic diet with sun exposure deprivation (n=4), G2 - hyperphosphatemic diet with sun exposure (n=4), G3 - balanced diet with sun exposure deprivation (n=4), and G4 - balanced diet with exposure to sunlight (n=4). The parameters for the trabecular bone (Trabecular Number, Trabecular Thickness, Trabecular Separation, Bone Pattern Factor, Fractal Dimension, Euler Number, Structural Model Index, Degree of Anisotropy, Eigenvalues 1, 2 and 3, and Centroides X, Y and Z), and cortical bone (Number of Closed Pores, Volume of Closed Pores, Surface of Closed Pores, Closed Porosity, Volume of Open Pores, Open Porosity and Total Porosity). The overall results showed that the structure and bone quality of group G3 and G4 were better than those of groups G1 and G2, and that the diet factor influenced more than the sun exposure factor. The computerized microtomography allowed to evaluate the quality of the cortical and trabecular bones of the Pantanal alligator tibia with osteometabolic disease. The diet and sun exposure factors influenced individually the results of the μCT parameters between the groups, demonstrating the functional and structural complexity. Thus, these parameters can contribute to the interpretation of the mechanical behavior of bones and correlate them with the risk of lesions and fractures associated with osteometabolic diseases.

Alumina foam microspheres by emulsion drop-casting in aqueous ammonium chloride solution

A facile method for the preparation of alumina foam microspheres from hydrogenated vegetable oil-in-aqueous alumina slurry (HVO-in-AAS) emulsions is reported. The HVO-in-AAS emulsions drop-cast in cold aqueous NH4Cl solution undergo fast gelation due to the freezing of HVO, physical cross-linking of carrageenan gelling agent and coagulation by NH4Cl. Emulsions of HVO to AAS volume ratios of 1.5–2.5 prepared from 10 and 20 vol% AAS are used for drop-casting. Microspheres with sphericity close to 1 are obtained by drop-casting in 5 wt% aqueous NH4Cl solution at −3 °C. The well-defined interconnected cellular structure observed in the core of the sintered alumina foam microspheres is distorted towards the surface due to emulsion destabilization by the NH4Cl. The porosity and cell size of the sintered alumina foam microspheres are independent of drop-casting bath conditions but depend on the emulsion composition. The microspheres have diameter, open pore volume and average cell sizes in the ranges of 2.38–2.49 mm, 1.22–2.42 cm3/g and 15.66–6.87 µm, respectively.

Properties of BioRoot RCS, a tricalcium silicate endodontic sealer modified with povidone and polycarboxylate.

To evaluate the chemical and physical properties of a tricalcium silicate root canal sealer containing povidone and polycarboxylate (BioRoot RCS), a calcium silicate MTA-based sealer containing a salicylate resin (MTA Fillapex), a traditional eugenol-containing sealer (Pulp Canal Sealer) and an epoxy resin-based root canal sealer (AH Plus). Calcium release, pH, setting time, water sorption, volume of open pores, volume of impervious portion, apparent porosity and weight loss were measured. The ability to nucleate calcium phosphates (CaP) after ageing 28days in a simulated body fluid was evaluated using ESEM-EDX and micro-Raman spectroscopy. Data were statistically analysed (P=0.05) using one-way anova (setting time, radiopacity, solubility, water sorption, porosity) or two-way anova (ion release tests). BioRoot RCS had a final setting time of 300min and adequate radiopacity (5.2mm Al). It demonstrated the highest (P<0.05) and more prolonged ability to release calcium ions (721ppm at 3h) and to increase the pH (11-12) (P<0.05); B-type carbonated apatite deposits were found on aged BioRoot RCS (biointeractivity-related CaP-forming ability). A final setting time of 270min and good calcium release (17.4ppm at 3h) were measured for MTA Fillapex; apatite deposits were present on aged samples. No calcium release and no alkalizing activity were measured for Pulp Canal Sealer and AH Plus; no CaP nucleation was detected on aged Pulp Canal Sealer, and some apatite deposits were found on aged AH Plus (chemi/physisorption-related CaP-deposition). Higher and significantly different (P<0.05) porosity, water sorption and solubility were measured for the two calcium silicate sealers, especially for BioRoot RCS. BioRoot RCS had bioactivity with calcium release, strong alkalizing activity and apatite-forming ability, and adequate radiopacity.

Flammability, comfort and mechanical properties of a novel fabric structure: plant-structured fabric

Traditional flame retardant (FR) treatments may bring detrimental effects on comfort as well as mechanical properties for cotton fabrics. This study investigates whether a novel fabric structure—plant-structured fabric can improve fabric performance after FR treatment. Here, plant-structure fabrics were compared with conventional fabrics of similar weight and thickness. The results revealed plant-structured fabrics tended to retain a higher level of comfort properties than the conventional plain and twill weave fabrics on wettability, thermal conductivity, air resistance and fabric hand feel. Moreover, the tearing strength and tensile strength of the plant-structured fabrics are strongly associated with a higher level of flame resistance as evaluated by the 45° flammability test. This can be attributed to higher fabric sett, the presence of closed pores between the two layers and lower open pore volume at its face. The weave pattern of fabrics was observed through microscope and the thermal decomposition behaviour of fabrics was evaluated by thermal gravimetric analysis.

Effect of synthesis temperature on structure-activity-relationship over NiMo/γ-Al2O3 catalysts for the hydrodesulfurization of DBT and 4,6-DMDBT

A series of γ-Al2O3 materials with different textural properties and acidities were synthesized from the boehmite sol by tuning the aging temperatures. NiMo supported catalysts were prepared by using γ-Al2O3 as the supports, then the catalytic HDS performance were evaluated by using DBT and 4,6-DMDBT to be the probe molecules. The physico-chemical properties of γ-Al2O3 supports and the corresponding NiMo catalysts were characterized by XRD, N2-physisorption, Py-IR, UV–Vis DRS, laser Raman spectra, H2-TPR, XPS, HRTEM methods. The characterization results showed that NiMo/γ-363 catalyst possessed a large pore size (12.0nm), open pore volume (0.86cm3g−1), moderate acidity and appropriate MSI. The NiMo/γ-363 catalyst presented the highest DBT and 4,6-DMDBT conversions at all the WHSVs. The NiMo/γ-363 catalyst showed highest kHDS and TOF values of the 4,6-DMDBT HDS, which could be ascribed to the synergistic effect of excellent textural properties, appropriate acidity and suitable MSI of the NiMo/γ-363 catalyst, moderate dispersion degree, high sulfidation degree and desirable stacking morphology of the MoS2 crystallites. The highest HYD/DDS ratio (1.51) of the 4,6-DMDBT HDS over the NiMo/γ-363 catalyst indicated that the HYD pathway was the main reaction route. Furthermore, a possible reaction network for 4,6-DMDBT HDS over the series of NiMo/γ-Al2O3 catalysts was proposed.

Bulk Aging of Graphite-Polypropylene Current Collectors Induced by Electrochemical Cycling in the Positive Electrolyte of Vanadium Redox Flow Batteries

Carbon-based bipolar plates (BPP) are essential components of the vanadium redox flow battery (VRFB) stack guaranteeing electrical conductivity and physical separation of adjacent cells. They are usually made of composite materials with complex structures containing conductive carbon components and polymer binder materials. In order to investigate their aging by simulation of repetitive charging/discharging conditions in areas with sluggish electrolyte flow, commercially available graphite-polypropylene BPPs were subjected to galvanodynamic treatment under diffusion limitation conditions in a three electrode electrochemical cell with positive electrolyte (VO2+/VO2+) using different states of charge (SOC). The current was swept between 100 and −100 mA/cm2. After aging, cyclic voltammetry (CV) in diluted H2SO4 was used to analyze the change in double layer capacitance and redox activity of the BPPs. Morphological investigations of the surface texture and bulk material were performed by means of scanning electron and confocal microscopies as well as by X-ray computed microtomography. After 3000 sweeping cycles in the positive electrolyte at high SOC the BPP showed an increase in double layer capacitance as well as higher roughness and increase in open pore volume in depths up to 100 μm. The aging effects are ascribed to oxidation and corrosion of the surface.

Formation of nonmetallic inclusions in the carburization of steel by high- and low-ash reagents

The solution of high-ash carburizing agents (dry-quenching dust, coke breeze) and low-ash agents (MU-95) in molten steel is studied. Relatively stable C–O and C–O–Fe complexes are formed on solution. When high-ash carburizing agents are introduced in the melt, the liberation of volatiles leads to decrease in their particle size, increase in the open pore volume, and faster exchange of carbon and iron between the phases. Carbon from low-ash carburizing agents dissolves mainly through the outer surface of the particles. The oxygen present forms CxOy complexes with the remaining carbon, on account of strong C–O bonds. Consequently, the assimilation rate of the carburizing agents is reduced. The solution of the inclusions may be accelerated by introducing optimal quantities of rare-earth elements that reduce the carbon–oxygen complexes.

Influence of fibers partially coated with rubber from tire recycling as aggregate on the acoustical properties of rubberized concrete

The aim of this study is to analyze the main parameters that influence the acoustic properties of lightweight concrete containing high volume of recycled rubber aggregates. To that end, the sound absorption and the sound insulation on rubberized concrete are tested under different frequencies. Concrete specimens were designed with 0–100% substitution of its coarse aggregate by two different rubber aggregates from recycled tires, which is up to a 60% of the overall concrete volume fraction. Moreover, to evaluate the influence of the external texture and the direct contact of rubber, concrete panels with different surface finishes (rough and smooth face) were casted. Crumb rubber (CR) and fibers partially coated with crumb rubber (FCR) have been studied for sound barriers. FCR are composed of steel and plastic fibers mixed with small rubber particles from recycled tires and obtained during the granulation process, before the complete rubber separation. The results of this research indicate that the combination of steel and textile fibers contaminated with rubber powder increase sound absorption when compared to ordinary or rubberized concrete. The addition of CR or FCR reduces concrete density and increases its open porosity. However, concrete with large VF of FCR presents an even larger volume of open pores than concrete with CR admixtures, which increases the sound absorption. In addition, the results obtained for sound insulation in high frequencies are also improved with CR and FCR, even when the concrete becomes lighter, because damping of CR and FCR concrete is enhanced. As a consequence, high VF of FCR (80–100%) can be incorporated to concrete for non-structural uses to increase sound absorption.

Characterization and Functional Applications of Nanoporous Ag Foams Prepared by Chemical Dealloying

In this study, the pure Ag nanoporous foams, with open cell pore volume fractions 55 to 70 pct and pore sizes 100 to 400 nm, have been prepared by chemical dealloying. The Ag nanoporous foams possess favorable modulus (~0.7 GPa) and strength (~14 MPa), much higher than most of the polymers or ceramic foams. It is found that the Ag nanoporous foams are appropriate candidates for the catalytic and electrode applications. However, they do not exhibit efficient anti-bacterial effect, unless much smaller bacteria with cell sizes of 100 nm or less in the neighborhood are encountered.