SAP Particles Research Articles

Research of Water Absorption and Release Mechanism of Superabsorbent Polymer in Cement Paste.

The water absorption and release properties of superabsorbent polymers' (SAP) internal curing agent are affected by many factors, such as solution properties, the ambient temperature and humidity and the particle size of SAP, which determine the curing effect and the durability of cement concrete structures directly. In this paper, the variation rule of the water absorbing capacity of SAP in simulated cement paste under different solutions and environmental conditions was studied. Based on microscopic image technology, the dynamic swelling behavior of the SAP particles was explored. The water release performance of SAP in cement paste was analyzed by both the tracer method and the negative pressure method. The results show that the water absorption of SAP in cement paste varied from 27 to 33 times. The ionic valence had a significant effect on the water absorption capacity of SAP, which suggests that the larger the ionic radius, the lower the absorption of SAP. The higher the temperature of the solution, the greater the water absorption rate of SAP. While the SAP particle size was less than 40-80 mesh, a slight 'agglomeration effect' was prone to occur, but the absorption state of SAP was more stable. Based on the swelling kinetic equation of SAP and the time-dependent swelling morphology of SAP in cement paste, a swelling kinetic model was established. The water release performance of SAP was less affected by the capillary negative pressures, and it would not release the water prematurely during the plastic stage, which was conducive to the continuous internal curing process of hardened paste in the later stage.

Isolation of Tobacco Mosaic Virus-Binding Peptides for Biotechnology Applications.

Tobacco mosaic virus (TMV) was the first virus to be discovered and it is now widely used as a tool for biological research and biotechnology applications. TMV particles can be decorated with functional molecules by genetic engineering or bioconjugation. However, this can destabilize the nanoparticles, and/or multiple rounds of modification may be necessary, reducing product yields and preventing the display of certain cargo molecules. To overcome these challenges, we used phage display technology and biopanning to isolate a TMV-binding peptide (TBPT25 ) with strong binding properties (IC50 =0.73 μM, KD =0.16 μM), allowing the display of model cargos via a single mixing step. The TMV-binding peptide is specific for TMV but does not recognize free coat proteins and can therefore be used to decorate intact TMV or detect intact TMV particles in crude plant sap.

Pyrazinacene luminescence enhancement by heat-activated surface adsorption and de-aggregation in a saponite colloidal system

This work presents heat-activated luminescence enhancement of butterfly-shaped pyrazinacene dye (BP) in an aqueous hybrid colloidal solution containing synthetic silicate, clay mineral saponite (Sap). The nitrogen-rich BP molecule consists of a quadruply benzo-fused fluorubine core N-alkylated at 6,13-positions with six hydrophilic [2-[2-(2-methoxyethoxy)ethoxy]ethoxy] chains to promote its solubility in polar solvents. BP exhibits strong luminescence emission especially in organic solvents. However, in aqueous solutions, BP dye alone usually aggregates, which leads to significantly weaker fluorescence. This effect can be overcome by using a mixed aqueous colloidal system containing Sap particles and BP dye molecules. This process is further promoted by heating the colloidal BP/Sap system to 70 °C, where the BP aggregates are irreversibly dispersed as monomers subsequently adsorbed at the surfaces of Sap particles. Following cooling to room temperature, the luminescence emission undergoes a several-fold increase in intensity. Such an improvement was not observed in aqueous solutions without the silicate or in hybrid colloids without thermal treatment. The heat-assisted irreversible adsorption of BP on Sap particles represents a simple stabilization method for fluorescence enhancement that can be applied to various other photoactive dyes in aqueous systems. This is essential to many applications, especially those involving biological systems, such as photosensitizers, luminescent sensors, or probes.

Research on the Influence of Water Storage Medium on early Planting Performance of Portland Cement Foamed Concrete

Adding sap particle, Portland cement foamed concrete was studied to manufacture a new type of planting material. The pH, porosity, permeable capacity, infiltration rate and water storage were tested for evaluating the performance of foamed concrete. Solid-liquid extraction method and image binaryzation were used to study the pH and porosity of foamed concrete. A kind of self-made permeable device was also used in this paper. It was found that the pH of foamed concrete could be decreased by sap particles absorbed the boric acid solution in 14 d. For the foaming effect of fresh concrete was disturbed by liquid from sap particles, the porosity of foamed concrete was increased and then decreased. Seepage channels could be formed in foamed concrete when sap particles shrunk for releasing liquid and they also would be block for sap particles expanding when water permeated into foamed concrete. The permeable capacity and infiltration rate were decreased with increasing sap particles. The water storage of foamed concrete was fluctuated with sap particles increasing but more than that without sap particles. The optimal dosage of sap particles was 0.3wt% of binder material in this study. At the dosage, the minimal pH of foamed concrete could be obtained and performance of that would be good to plant, such as permeable capacity, infiltration rate and water storage.

Effects of Reaction Parameters on Water Absorption of Poly(itaconic acid) Superabsorbent Particles Synthesized by Inverse Suspension Polymerization

Inverse suspension polymerization method was applied to prepare poly(itaconic acid) based superabsorbent particles. The polymerization process was investigated to determine the influence of different parameters on the water absorption properties. It was found that processing parameters, such as oil/aqueous phase ratio, surfactant, stirring speed, as well as concentrations of initiator and crosslinker needed to be optimized to achieve high water absorbency. The hydrolysis sensitivity of the divinyl crosslinker in water affected the crosslinking efficiency to show better performance with hydrolytically stable diacrylamide than diacrylate. The washing solvent to remove surfactant also highly influence the water absorbency of the prepared SAP particles, and solvent with lower polarity induced the collapse of the pores in the SAP particles to give lower value of water absorbency.

Modelling and experimental characterization of unsaturated flow in absorbent and swelling porous media

The present study addresses unsaturated flow in swelling porous media. The investigated materials are made of super absorbent polymer granules (SAP) blended with cellulose fibres (fluff), relevant to absorbent hygiene products (AHP). A model is developed based on mass and momentum balance equations taking into account the morphological modifications due to the swelling of SAP particles during water absorption under saturated and/or unsaturated liquid conditions. Constitutive equations for the composite medium express the kinetics of water absorption, the hydraulic conductivity, the relative permeability and the hysteretic patterns upon imbibition and drainage. The model is validated and compared with results of experimental campaigns performed in unsaturated conditions using AHP samples with different SAP/fluff mass ratio (SFR). The systematic deviation between computed and experimental results in the very early stages of the tests is interpreted in the light of percolation theory, and model improvements are achieved implementing the finite-scale effects method.

Absorption characteristics and shrinkage mitigation of superabsorbent polymers in pavement concrete

ABSTRACT To explore the absorption characteristics and swelling behaviour of SAPs under different working conditions of pavement concrete, the optical microscopy was conducted to capture the swelling process during the absorption period. Then, the absorption kinetic parameters were deduced, and swelling models were developed at different working temperatures. Furthermore, the humidity and shrinkage of pavement concrete were monitored synergistically at multiple scales with a cloud signal acquisition system, and the pore structures and hydration products were analysed by mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) observations. The results show that a relatively high temperature increases the SAP absorption and the absorption rate. The hydrophobic interaction of the SAP groups and the hydrogen bonding between the macromolecular chains alter the time point of the gel phase change. Increasing the temperature accelerates the swelling rate of SAP gel network and increases the SAP absorption. Various water film layers emerge and become narrow within the early transient seconds as the SAP particles begin to crosslink and aggregate. A period of accelerated shrinkage occurs within 100 h in the SAP-pavement panel. At 28 days, SAP increases the concrete porosity but refines the pore structure, and additional hydration products are formed.

Decreased vitality and viability of Escherichia coli isolates by adherence to saponite particles

This work was aimed at a detailed analysis of the interaction between Gram-negative bacteria of Escherichia coli and synthetic saponite (Sap), with the main focus on the changes in viability (survival) and/or vitality (metabolic activity) that are relevant parameters for evaluating the fitness of different microorganisms. The tested bacterial strains originated from various environmental and clinical sources, representing E. coli with different properties in terms of resistance and biofilm production. This included characteristics related to the cell surface structures (adhesins) that are thought to facilitate the adhesion of bacteria to Sap particles. Sap particles at a concentration of 5 mg/mL demonstrated an antimicrobial effect on all the tested E. coli isolates. The other tested concentrations (2.5 and 1.25 mg/mL) were efficient in a strain-dependent manner. The interaction between bacteria and Sap particles was affected more by viability than vitality, indicating a bacteriostatic mode of action by Sap. To obtain deeper insights into the mode of action of Sap, microscopy evaluations including fluorescence in situ hybridization (FISH) were used. The results of the FISH assay showed the ratio of live/dead E. coli cells after the adhesion to Sap particles for different time periods (4 h, 12 h and 24 h) and revealed that the cells adhered to Sap particles had remained active but lost their ability to multiply. Moreover, after the 18-h incubation, inactive bacterial cells were detected in the inner layers of Sap. Scanning electron microscopy confirmed damage of the cell surface of bacteria firmly bound to Sap particles. From the group of 4 tested genes for the fimA, pap, afa, and aaf adhesins, only the FimA and Pap genes were proven by PCR in some strains and a correlation between changes in viability/vitality and those genes was not observed. It seems that physico-chemical interactions rather than bacterial surface structures play a significant role in the interaction between Sap particles and the bacterial surface.

Resonance energy transfer in the systems of smectite modified with a fluorescent cationic polymer and a photosensitizer

The hybrid materials studied in this work consisted of synthetic saponite (Sap) particles, dextran polymer with positively charged alkylammonium and fluorescein luminophore groups (FITC), and photosensitizer - phloxine B (PhB). Solid films of these materials were prepared by vacuum filtration from colloidal precursors. The film composition has been designed in such a way that the amount of fluorescently active components was constant and only the ratio between chromophores and the amount of Sap was changed. Based on this, it was possible to evaluate the optical properties of the materials as a result of the interactions and equilibria taking place between the components. In addition to the basic characterization of materials, the emphasis was on evaluating the spectral properties of the films and their colloidal precursors. The composition of the systems and the interactions between the components significantly affected the equilibria between the anionic forms of both FITC and PhB. Such changes were also significantly reflected in the photoactivity and fluorescence properties of the samples. The aim was to prepare films that exhibit efficient absorption of visible light and excitation energy transfer from FITC groups to PhB molecules. The potential importance of materials of this type is briefly discussed.

Insights into the Rheological Behavior of Aqueous Dispersions of Synthetic Saponite: Effects of Saponite Composition and Sodium Polyacrylate

Synthetic saponite (Sap) easily delaminates in water to form a transparent sol and hydrogel with excellent rheological performance and is thus widely used in paints, cosmetics, and nanomaterials. The thixotropic property of Sap hydrogels is heavily dependent on the nature of Sap and the external electrolyte and polyelectrolyte; yet, details on the relationship between rheological behaviors of saponite hydrogels and Sap composition and polyelectrolyte remain unclear. In this work, thixotropic rheological behaviors of a series of synthetic Sap hydrogels, with and without added sodium polyacrylate polyelectrolyte (NaPA), were investigated. The Sap samples, with a Si/Al molar ratio from 5 to 25, were successfully synthesized using hydrothermal methods and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The rheological performances of aqueous Sap dispersions and particle sizes and ζ-potentials of Sap were measured. The results showed that the crystallinity of the Sap increased with an increasing Si/Al molar ratio. All Sap samples, with the exception of the Sap with a Si/Al molar ratio of 5, dispersed well in water (3 wt %) to form hydrogels. The rheological behaviors of the hydrogels were related to the chemical composition and the layer charge of the Sap. The Sap with a Si/Al molar ratio of 25 had higher viscosity due to improved delamination. The addition of the NaPA, an anionic polyelectrolyte, into the hydrogels decreased the viscosity and altered the thixotropic properties such that the hydrogel becomes a sol. The addition of NaPA facilitated the dispersion and delamination of Sap, because under the electric field of negatively charged Sap particles in the hydrogel, the anionic NaPA was instantaneously polarized and thereby entered the hydration layer of the Sap particles.

Resonance Energy Transfer between Dye Molecules in Colloids of a Layered Silicate. The Effect of Dye Surface Concentration

Colloidal dispersions were prepared from a synthetic layered silicate of saponite type (Sap) and two cationic laser dyes, rhodamine 6G (R6G) and oxazine 4 (Ox4). The adsorption of dye molecules on Sap particles led to neither molecular aggregation nor segregation of dye molecules. Forster resonance energy transfer (FRET), investigated using steady-state and time-resolved fluorescence (TRF) spectroscopies, occurs from R6G to Ox4, and the efficiency increased with the surface concentration of adsorbed dye molecules, as determined by the dye/Sap ratio. Theoretical modeling of FRET based on defining probability density functions of intermolecular distances is presented. The theoretical model and experimental results were in very good agreement. Diffusion of the molecules might have contributed to the increase of FRET efficiency, especially at lower dye concentrations, whereas the influence of anisotropy factors was most likely negligible.

Enhanced luminescence of 3,3′-diethyl-2,2′-thiacyanine cations adsorbed on saponite particles

Hybrid colloidal dispersions based on cationic dye 3,3′-diethyl-2,2′-thiacyanine iodide (NK88) and saponite (Sap) were prepared and their spectral properties were compared with dye solution. The effect of various NK88/Sap ratios was investigated by absorption and fluorescence spectroscopies. A detailed analysis of absorption spectra based on chemometric methods (principal component analysis and multivariate curve resolution - alternating least squares) revealed a very complex nature of these hybrid systems. Most relevant spectral components were identified as monomeric form, H- and J-aggregates. The rearrangement of initially formed dye species with time led to the increase of the amount of the J-aggregates at the expense of the H-aggregates and the monomers. The larger amounts of the H-aggregates were observed in the specimens with relatively highest dye loadings. NK88 luminescence was significantly enhanced upon the adsorption on Sap particles, but could not be assigned to a single dye form. The participation of different dye forms can explained in terms of strong couplings, such as collective exciton delocalization in dye supramolecular systems formed on Sap surface, and weak coupling between various forms via excitation energy migration and transfer. These interactions led to the emission spectra, whose profiles did not depend on the excitation wavelengths. The colloidal systems based on NK88 and Sap are perspective precursors for hybrid materials with interesting optical and photophysical properties.

Recommended method for measurement of absorbency of superabsorbent polymers in cement-based materials

The application of superabsorbent polymers in concrete technology is now becoming a reality in several places in the world. Independently of the specific technical application involving any of the hydrogels, the design of cement-based materials requires that the knowledge on the absorbency of superabsorbent polymers in cementitious environments is well determined. It is vital that a generalized agreement over which method should be utilized with this regard is obtained, so large-scale industrial applications can be developed with sufficient quality and safeguards. There ought to be a standard method so that the properties of concrete with superabsorbent polymers can be better controlled in practice. In this paper, a technique that can be potentially used as a standard method is developed. The method is based on a measurement technique validated through an international standard procedure—laser diffraction particle size analysis, and it allows an easy and reliable measurement of the absorbency of superabsorbent polymers. It is shown in detail how both the definition of the exposure liquid and the definition of the system of SAP particles can be selected so that absorbency can be experimentally obtained. It is suggested that this method can be recommended as a standard method for measuring liquid absorption of superabsorbent polymers in cementitious environments.

First Report of Bidens mottle virus Causing Mosaic and Leaf Deformation in Garland Chrysanthemum and Lettuce in Taiwan.

Garland chrysanthemum (Chrysanthemum coronarium) and lettuce (Lactuca sativa) are winter vegetables in Taiwan. Turnip mosaic virus (TuMV) and Lettuce mosaic virus (LMV) were potyviruses commonly isolated from garland chrysanthemum and lettuce, respectively (1). Symptoms of mosaic and deformation in leaves and stunting of plants have been observed in both Compositae crops in the fields since 2007 in the Chiayi area and with an increasing incidence in recent years (26 and 33% in garland chrysanthemum and lettuce, respectively). Filamentous virus particles (approximately 780 × 13 nm) in the crude sap and pinwheel inclusions in infected cells can be observed in the preparations of both diseased hosts with electron microscopy. However, TuMV, LMV, and other potyviruses (Bean yellow mosaic virus, Papaya ringspot virus, and Zucchini yellow mosaic virus) were not detectable in diseased samples by ELISA and western blotting tests, indicating a new potyvirus infection. Virus cultures were isolated from infected garland chrysanthemum and lettuce separately via mechanical inoculations in Chenopodium quinoa. Each isolate was mechanically inoculated to their original host individually and all caused symptoms similar to that observed in the field, indicating their pathogenicity to their original host. A cDNA fragment consisting of partial nuclear inclusion (NIb) and coat protein (CP) genes were amplified with potyvirus degenerate primers (forward: 5'-GGBAAYAATAGTGGNCAACC and reverse: 5'-GGGGAGGTGCCGTTCTCDATRCACCA) and was found to share 90% nucleotide sequence identity to that of Bidens mottle virus (BiMoV; GenBank Accession No. AF538686). The sequences of the CP gene and 3' untranslated region (3'-UTR) of tested viruses were further amplified with a specific primer of BiMoV CP and oligo-dT in reverse transcription-PCR. The amplified fragments were cloned, sequenced, and the combined cDNA sequences were deposited in GenBank (Accession No. AB491763 for isolate garland chrysanthemum and Accession No. AB491764 for isolate lettuce). Sequence analysis showed that both cloned sequences shared more than 97% nucleotide similarity to that of BiMoV. The amino acid sequence of the CP of both isolates shared a 99.3% identity and a 98.9 to 99.3% identity to that of other BiMoV isolates deposited in GenBank. BiMoV was first described to be infecting lettuce and Cichorium endivia in the United States (4) and was first reported in sunflower and calendula in Taiwan recently (2,3). To our knowledge, this is the first report of the occurrence of BiMoV in garland chrysanthemum and lettuce in Taiwan.

Revisiting the protected paste volume concept for internal curing of high-strength concretes

Internal curing of high-strength concrete has been the subject of extensive research for the last decade. The concept of protected paste volume has been one of the most significant theoretical approaches to internal curing. In this paper, the applicability of the protected paste volume concept to internal curing is re-evaluated in view of recent experimental evidence. It is shown, that the concept of protected paste volume and recommendation to limit the spacing factor to approximately 200 μm, cannot be extended to internal curing of high-strength concrete, since the distance of penetration of the internal curing water into the surrounding matrix depends mainly on the availability of internal curing water to the surrounding cementitious matrix. The pore structure of LWA and the size of SAP particles seem to have a marked influence on the availability of internal curing water and thus are factors of greater importance than the spacing factor.

Silver Nanoparticles in Blends of Polyethylene and a Superabsorbent Polymer: Morphology and Silver Ion Release

Antimicrobial properties of polymer materials are required in many applications. The poly-ethylene/superabsorbent polymer (PE/SAP) blends containing silver nanoparticles were successfully prepared via thermal reduction during melt mixing. It was found that in situ formed silver nanoparticles are preferentially located at the interface between PE matrix and SAP particles. The expectation was that the low water uptake of the PE will be enhanced by blending with a SAP and thus the silver ion release from the material will increase. Surprisingly, the silver ion release was markedly suppressed by the addition of SAP. This finding is explained by the preferential sorption of silver ions by the SAP particles.

Preparation and properties of swellable thermoplastic elastomer alloys based on elastomeric powder, polypropylene, and superabsorbent polymer

This paper focuses on the development of swellable thermoplastic elastomer alloys based on elasto- meric powder, polypropylene, and superabsorbent poly- mer. The mechanical and swelling properties of the resulting materials were investigated at varying concentra- tions of the components and by compatiblization between the rubber particles of the elastomeric powder and the poly- propylene phase using the peroxide 2,5-dimethyl-2,5di (t-buthylperoxy)hexane as compatibilizer. The materials obtained could be processed by injection molding in the same way as thermoplastics. The mechanical and swelling properties of the materials could be controlled by shifting the concentrations of the components. The swelling proper- ties in different swelling media were investigated. A maxi- mum of 120% of the relative increase of mass was obtained using KOH solution. The positions of the SAP particles within the material were detected by a combined method of SEM and EDX scan. Elastomeric powder and thermoplastic build the matrix material, in which the SAP particles are embedded mechanically. A schematic illustration of the ma- terial structure was developed, and the liquid was sus- pected to be transported by diffusion into the material matrix as well as along the interface between SAP and the matrix material. The results obtained can be used for the design of improved sealing concepts, as they evidence a good method of using recycled elastomers. V C 2010 Wiley Peri-

Rheology and hardened properties of single-coat render mortars with different types of water retaining agents

This paper compares the effect of two different water retaining agents in single-coat render mortars. The water retaining agent used in the experiments were cellulose methyl–hydroxypropyl and super absorbent polymers with various contents ranging from 0.05 to 0.15 wt.% of the total weight. Properties in fresh and hardened state were investigated. Fresh state properties include rheological behaviour, slump and density. Mechanical strength, transport properties through capillary absorption tests and water retaining capacity were measured in hardened state. Results indicate that MHPC promote the cohesion between the material particles in fresh state, increase the cohesiveness and is more efficient in fixing water molecules within their structure but, may lead to lower strength in the hardened state. SAP particles can also be used as water retaining admixtures, although they influence drastically the rheological parameters, specially the yield stress, traduced in removing water from the mixture, promoting a decrease on workability. However, the use of a plasticiser can help to circumvent this decrease of workability and, the higher flexural and compressive strength results of SAP mixtures indicate that SAP particles are more efficient to promote adequate water retention, even in adverse conditions.

Bland Embolization of Hepatocellular Carcinoma Using Superabsorbent Polymer Microspheres

The purpose of this study was to investigate the clinical outcomes of bland embolization using superabsorbent polymer microspheres (SAP-TAE) as an initial therapeutic option for previously untreated hepatocellular carcinoma (HCC) ineligible for resection or ablation. Fifty-nine patients with previously untreated HCC unamenable to surgery or ablation underwent bland embolization using 100- to 200-mum reconstituted SAP particles (SAP-TAE) as the initial treatment. SAP-TAE was repeated as needed based on tumor response but was switched to chemoembolization when necessary to control residual or progressive tumor. Early tumor response was assessed by contrast-enhanced CT according to RECIST and EASL criteria 1 month after the initial SAP-TAE. The overall survival was calculated using the Kaplan-Meier method. The overall mean follow-up period was 30.6 months (range, 7-59 months). A total of 121 sessions of SAP-TAE were performed, with 1-5 sessions per patient (mean, 2.1 sessions). The mean period of repeated SAP-TAE was 15.6 months (range, 1-51 months), and it exceeded 1 and 2 years in 32 (54%) and 15 (25%) patients, respectively. Thirteen (22%) patients underwent repeated SAP-TAE alone, and the remaining 46 (78%) patients underwent subsequent chemoembolization. No major complication was observed and postembolization syndrome was minimal after SAP-TAE in all patients. Response rate was 14% and 66% by RECIST and EASL criteria, respectively. Overall survival rates were 100% and 83% at 1 and 2 years, respectively, and median survival time was 30 months. In conclusion, SAP-TAE was a safe and repeatable option as the induction therapy for HCC unamenable to surgery or ablation, despite the high incidence of converting to TACE during the total course.

Natural Virus Infection of Hedge Bindweed (Calystegia sepium)

Virus symptoms were observed on Hedge bindweed (Calystegia sepium) a well known plant in Hungary. In the literature there is no record of virus infection on Hedge bindweed, therefore, investigations were carried out to determine the causal agent. Sap from leaves showing virus-like symptoms was inoculated onto test plants inducing systemic infection on Nicotiana clevelandii, N. benthamiana, local lesions on Chenopodium quinoa and no infection on Datura stramonium and Cucumis sativus. Sap of N. clevelandii was examined by electron microscopy, showed the presence of long flexous particles. The biological and other properties of the virus have also been studied. Properties of particles in sap were as follows: TIP (thermal inactivation point): 78 °C, LIV (longevity in vitro): 26 days and DEP (dilution end point): log 10 minus 5. The size of coat protein is 36 kDa, and the genome consists of 7-8000 nt RNA. Double-stranded cDNA were produced using random hexanucleotide primers, cloned and sequenced. BLAST search of sequence databases revealed nucleotide sequence identity with carlaviruses. Further investigations are needed to decide whether the virus isolated from Hedge bindweed is a new carlavirus or a new strain of an existing carlavirus.