Swelling Ratio Values Research Articles

Stretchable Composite Films Are Prepared by Using Cellulose Pulp with Differential Substitution of Carboxymethyl Cellulose and Thymol with an Infrared Heating Process for Packaging Application.

Herein, cellulose pulp (CP), carboxymethyl cellulose (CMC), and thymol-based eco-friendly, transparent, and flexible composite films are prepared. These materials dissolved well in an environment-friendly process in N-methyl morpholine N-oxide (NMMO) ionic liquids using infrared heating. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses are used to study the structure, microstructure, and morphology of the composite films. The thermal properties of the CP/CMC/thymol composites are thoroughly studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal stability of the composites (T 5%-57.8-91.2 °C and T 10%-216.6-284.1 °C) significantly improves following the CMC addition. In each case, all the composite film exhibits unique T g (140.5-143.1 °C) values, as confirmed by DSC. The tensile strength of the cellulose pulp is 66.5 MPa, increasing to 78.4 MPa for the CP/CMC-1:0.5 composites and steadily increasing to 93.8 MPa with increasing CMC content. Similarly, CMC increases the EB of cellulose pulp from 9.3 to 7.4%. The water vapor permeability and swelling ratio values of the CP/CMC/thymol composites are in the range of 1.9-2.11 × 10-9 g/(m2·Pa·s) and 52.5-50.8° respectively. The CP, CMC, and thymol-based composite do not exhibit cytotoxicity to the aneuploid immortal keratinocyte cell line and demonstrate excellent antioxidant properties, for promising packaging and biomedical applications.

Deep Cleaning of Crystal Violet and Methylene Blue Dyes from Aqueous Solution by Dextran-Based Cryogel Adsorbents.

Polysaccharides have recently attracted growing attention as adsorbents for various pollutants, since they can be extracted from a variety of renewable sources at low cost. An interesting hydrophilic and biodegradable polysaccharide is dextran (Dx), which is well-known for its applications in the food industry and in medicine. To extend the application range of this biopolymer, in this study, we investigated the removal of crystal violet (CV) and methylene blue (MB) dyes from an aqueous solution by Dx-based cryogels using the batch technique. The cryogel adsorbents, consisting of cross-linked Dx embedding a polyphenolic (PF) extract of spruce bark, were prepared by the freeze-thawing approach. It was shown that the incorporation of PF into the Dx-based matrix induced a decrease in porosity, pore sizes and swelling ratio values. Moreover, the average pore sizes of the DxPF cryogels loaded with dyes further decreased from 42.30 ± 7.96 μm to 23.68 ± 2.69 μm, indicating a strong interaction between the functional groups of the cryogel matrix and those of the dye molecules. The sorption performances of the DxPF adsorbents were evaluated in comparison to those of the Dx cryogels and of the PF extract. The experimental sorption capacities of the DxPF cryogel adsorbents were higher in comparison to those of the Dx cryogels and the PF extract. The DxPF cryogels, particularly those with the highest PF contents (sample DxPF2), demonstrated sorption capacities of 1.2779 ± 0.0703 mmol·g-1, for CV, and 0.3238 ± 0.0121 mmol·g-1, for MB. The sorption mechanisms were analyzed using mathematical models, including Langmuir, Freundlich, Sips and Dubinin-Radushkevich isotherms, and kinetic models, like pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intra-particle diffusion (IPD). The sorption process was best described by the Sips isotherm and PSO kinetic models, indicating chemisorption as the dominant mechanism. This study outlines the importance of developing advanced renewable materials for environmental applications.

A comprehensive in vitro characterization of non-crosslinked, diverse tissue-derived collagen-based membranes intended for assisting bone regeneration.

Collagen-based membranes are class III-medical devices widely used in dental surgical procedures to favour bone regeneration. Here, we aimed to provide biophysical and biochemical data on this type of devices to support their optimal use and design/manufacturing. To the purpose, four commercial, non-crosslinked collagen-based-membranes, obtained from various sources (equine tendon, pericardium or cortical bone tissues, and porcine skin), were characterized in vitro. The main chemical, biophysical and biochemical properties, that have significant clinical implications, were evaluated. Membranes showed similar chemical features. They greatly differed in morphology as well as in porosity and density and showed a diverse ranking in relation to these latter two parameters. Samples highly hydrated in physiological medium (swelling-ratio values in the 2.5-6.0 range) and, for some membranes, an anisotropic expansion during hydration was, for the first time, highlighted. Rheological analyses revealed great differences in deformability (150-1500kPa G') also alerting about the marked variation in membrane mechanical behaviour upon hydration. Samples proved diverse sensitivity to collagenase, with the cortical-derived membrane showing the highest stability. Biological studies, using human-bone-derived cells, supported sample ability to allow cell proliferation and to prompt bone regeneration, while no relevant differences among membranes were recorded. Prediction of relative performance based on the findings was discussed. Overall, results represent a first wide panel of chemical/biophysical/biochemical data on collagen-based-membranes that 1) enhances our knowledge of these products, 2) aids their optimal use by providing clinicians with scientific basis for selecting products based on the specific clinical situation and 3) represents a valuable reference for optimizing their manufacturing.

Iron(III) cross-linked hydrogels based on Alteromonas macleodii Mo 169 exopolysaccharide

Recently, polysaccharide-based hydrogels crosslinked with the trivalent iron cation have attracted interest due to their remarkable properties that include high mechanical stability, stimuli-responsiveness, and enhanced absorptivity. In this study, a Fe3+ crosslinked hydrogel was prepared using the biocompatible extracellular polysaccharide (EPS) secreted by the marine bacterium Alteromonas macleodii Mo169. Hydrogels with mechanical strengths (G') ranging from 0.3 kPa to 44.5 kPa were obtained as a result of the combination of different Fe3+ (0.05–9.95 g L−1) and EPS (0.3–1.7 %) concentrations. All the hydrogels had a water content above 98 %. Three different hydrogels, named HA, HB, and HC, were chosen for further characterization. With strength values (G') of 3.2, 28.9, and 44.5 kPa, respectively, these hydrogels might meet the strength requirements for several specific applications. Their mechanical resistance increased as higher Fe3+ and polymer concentrations were used in their preparation (the compressive hardness increased from 8.7 to 192.1 kPa for hydrogel HA and HC, respectively). In addition, a tighter mesh was noticed for HC, which was correlated to its lower swelling ratio value compared to HA and HB. Overall, this preliminary study highlighted the potential of these hydrogels for tissue engineering, drug delivery, or wound healing applications.

COMPARISON OF BRACKET WATER DESALINATION TESTS IN THE FORM OF POWDER, GRANULES AND GREEN ALGAE HYDROGEL

This research was motivated by the problem of lack of clean water around the coast of Rainbow Beach in Karawang because the water quality is poor and still brackish. Untreated brackish water poses a risk to human health if drunk for a long time and can trigger skin diseases if used for bathing. The well water taken is located in the Pelangi Coastal Area, Pedes Karawang. This research aims to test the ability of brackish water desalination using powder, granules, and three variations of green algae hydrogel. This research uses a quasi-experimental method by comparing it with zeolite as a standard for brackish water desalination. The research results show that the resulting hydrogel preparation has a solid, brittle shape, a dark green color, and a distinctive odor of green algae. The best viscosity value is in the H4 formula. All green algae hydrogel formulas have good pH values, while the best swelling ratio value is in the H2 formula, and the best gel fraction value is in the H4 formula. From the results of the research that has been carried out, it can be concluded that the hydrogel, granule, and green algae powder preparations can desalinate brackish water based on the results of pH, temperature, salinity, sodium ion, and magnesium ion tests compared with zeolite, where the 6 g hydrogel preparation shows the best desalination capability of brackish water at the three well sample points

Innovative Materials with Possible Applications in the Wound Dressings Field: Alginate-Based Films with Moringa oleifera Extract.

For a long time, biopolymers have proven their effectiveness in the development of materials with various applications, lately those intended for the biomedical and pharmaceutical industries, due to their high biocompatibility and non-toxic, non-allergenic, and non-immunogenic nature. The ability to incorporate various active substances in this matrix has yielded materials with characteristics that are far superior to those of classic, conventional ones. The beneficial effects of consuming Moringa oleifera have promoted the use of this plant, from Ayurvedic to classical medicine. The addition of such compounds in the materials intended for the treatment of surface wounds may represent the future of the development of innovative dressings. This study followed the development of materials based on sodium alginate and moringa powder or essential oil for use as dressings, pads, or sheets. Thus, three materials with the addition of 10-30% moringa powder and three materials with the addition of 10-30% essential oil were obtained. The data were compared with those of the control sample, with sodium alginate and plasticizer. The microtopography indicated that the materials have a homogeneous matrix that allows them to incorporate and maintain natural compounds with prolonged release. For example, the sample with 30% moringa essential oil kept its initial shape and did not disintegrate, although the swelling ratio value reached 4800% after 20 min. After testing the mechanical properties, the same sample had the best tensile strength (TS = 0.248 MPa) and elongation (31.41%), which is important for the flexibility of the dressing. The same sample exhibited a very high antioxidant capacity (60.78% inhibition). The materials obtained with moringa powder added presented good values of physical and mechanical properties, which supports their use as wound dressings for short-term application and the release of embedded compounds. According to the obtained results, all the biopolymeric materials with moringa added can be used as dressings for different wound types.

Evaluation of properties and performance of poly(ether sulfone ketone) membranes in proton exchange membrane fuel cells

AbstractTwo series of sulfonated poly(ether sulfone ketone)s have been synthesized. The effect of different ratios of sulfone: ketone functional groups on the properties and performance of membranes is studied. The density, ion‐exchange capacity, water absorption, swelling ratio, proton conductivity, thermal and oxidative stability of membranes are determined. The results showed that membranes with higher contents of sulfone functional groups show lower density and consequently higher water absorption and swelling ratio values. A precise evaluation of the effect of different sulfone: ketone functional group ratios on the analytical acid concentration and the effective proton mobility and their relationship with water absorption have been performed. The proton conductivity values are between 71–78 mS.cm−1 at 30°C and 117–208 mS.cm−1 at 80°C. The effective proton mobilities at 80°C are in the range of 10.27 × 10 −4 to 16.68 × 10 −4 cm2.V−1.s−1. The highest current density for prepared membranes in H2/O2 single cell at 100% relative humidity and 80°C is 1900 mA.cm−2.

Poly(poly(ethylene glycol) methyl ether methacrylate-co-acrylonitrile) gel polymer electrolytes for high performance lithium ion batteries: Comparing controlled and conventional radical polymerization

In this work, a series of crosslinked poly(poly(ethylene glycol) methyl ether methacrylate-co-acrylonitrile) [P(PEGMA-co-ACN)] copolymers has been designed as gel polymer electrolytes (GPEs) for high-safety and high voltage lithium ion batteries. Two approaches including conventional free radical polymerization (FRP) and control radical polymerization (CRP) through one-step reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) were used to synthesize GPEs with different molar ratios of ACN and PEGMA. Although there was not observed remarkable advantage of polymerization method in different monomer compositions, P(PEGMA-co-ACN) by 50 mol.% ACN and PEGMA prepared via FRP exhibited the maximum ionic conductivity of 5.1 * 10−3 S cm−1, transference number (t+) of 0.55, and exceptional swelling ratio value of 150% in 30 min. Interestingly, it affords a supreme electrochemical stability window up to 5.13 V vs. Li/Li+, the charge capacity of 205 mAh g−1 at 0.1 C, and capacity retention of 89% after 100 cycles.

Utilization of an Acellular Cartilage Matrix‐Based Photocrosslinking Hydrogel for Tracheal Cartilage Regeneration and Circumferential Tracheal Repair

AbstractAcellular cartilage matrix (ACM)‐based hydrogels hold promise for use in the context of tracheal cartilage regeneration owing to the ease with which they can be molded into specific shapes and their intrinsic cartilage‐specific microenvironmental properties. In this report, an acrylic anhydride‐modified ACM (Ac‐matrix) hydrogel is fabricated for utilization in the context of tracheal cartilage regeneration and circumferential tracheal repair. Hydrogels are successfully prepared with a range of Ac‐matrix concentrations (4%, 6%, and 8%) and found that mechanical strength increases with rising Ac‐matrix concentrations whereas swelling and degradation ratio values decline. These Ac‐matrix hydrogels exhibit satisfactory cytocompatibility when loaded with chondrocytes. Chondrocyte‐loaded 6% hydrogels are able to support cartilage formation both in vitro and in vivo across a range of chondrocyte densities (5, 10, 20, and 40 million chondrocytes per mL), with increasing density being conducive to more homogenous cartilage formation. A homogeneously tubular tracheal cartilage construct is additionally generated and supports circumferential tracheal reconstruction in a rabbit tracheal lesion model system, with a biological structure and function consistent with those of the native trachea. These results suggest that this Ac‐matrix hydrogel platform is well‐suited to use in the context of tracheal cartilage regeneration, thus offering the potential to support circumferential tracheal reconstruction.

Karakteristik Fisik, Kimia, dan Fungsional Pati Ubi Banggai Asetat pada Berbagai Variasi Waktu Reaksi

Banggai yam plant (endemic in Banggai Kepulauan Regency) is a potential raw material in production of modified starch. The one of techniques to increase the value of starch is modification of starch by acetylation method. This study objectives to determine the physical, chemical and functional characteristics of Banggai acetate yam starch at various reaction times. The study used a Completely Randomized Design with treatment time reaction (T), namely T1: 30 min, T2: 35 min, T3: 40 min, T4: 45 min, T5: 50 min, T6: 55 min. This study was conducted to determine the characteristics of yam acetate starch, which includes percent acetyl, degree of substitution, water and oil holding capacity (WHC/OHC), flammability, solubility, moisture content, ash, fat, protein, starch and amylose starch. The results showed that the longer reaction time under certain conditions will increase the acetyl percent, degree of substitution, WHC, OHC, flareability, solubility but reduce levels of fat, water, ash, fat, protein, starch and amylose starch, yam acetate. In this study at the best reaction time is (50 min), gives the acetyl percent 8.658% and substitution degree of 0.356, the value of WHC, OHC, Swelling ratio and solubility of 32.21%, 30.21%, 1.98 g/g, and 19.17% respectively.

Development of gelatin aerogels reinforced with graphene oxide by microwave-assisted synthesis: Influence of the synthesis conditions on their physicochemical properties

Gelatin aerogels reinforced with graphene oxide (GO) at different pH values of GO and Gelatin:GO ratios were developed by microwave (MW)-assisted synthesis. The chemical characterization demonstrated noncovalent and covalent interactions under acidic and alkaline conditions, respectively. The elastic modulus increased 6 times and 1.38-fold, and the swelling ratio (SR) increased 1.2-fold and 1.4 times for aerogels at acidic and alkaline pH, respectively, when the gelatin content increased. The surface charge shifted from positive to negative values by increasing the pH. Additionally, a higher SR value was found for the aerogel synthesized in alkaline environment and lowest Gelatin:GO ratio, and its properties were compared to an aerogel synthesized by traditional processes to validate the MW as synthesis method. Similar physicochemical properties were identified in both aerogels, with an increase in the SR value for the MW synthetized aerogel of 1.5 times. This study provides a new synthesis method to develop gelatin-GO aerogels.

Synthesis, characterization and evaluation of swelling ratio on magnetic p53-poly(MAA-co-EGDMA)@GO-Fe3O4 (MIP@GO-Fe3O4)-based p53 protein and graphene oxide from kusambi wood (Schleichera oleosa)

The p53 protein plays an important role by acting as a transcription factor to regulate gene expression and its genetic mutation has been reported as the most common genetic alterations in human cancer diseases. This opens possibilities for the development of early identification of cancer by utilizing p53 protein as tumor biomarkers. In this work we report the synthesis, characterization and evaluation of p53-poly(MAA-co-EGDMA)@GO-Fe3O4 as SPE materials for selective extraction of wild p53 protein. The magnetic material p53-poly(MAA-co-EGDMA)@GO-Fe3O4 (MIP@GO-Fe3O4) is successfully prepared with GO-Fe3O4 from kusambi wood (Schleichera oleosa) as the host material, p53 as a template molecule, methacrylic acid (MAA) as a monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, benzoyl peroxide (BPO) as an initiator and acetone/ethanol as a porogen. Synthesis is carried out using a bulk polymerization method. To find out the best ratio that produces the highest MIP@GO-Fe3O4 mass, the five variations of the volume ratio of template, monomer and crosslinker (P1–P5) are investigated. It was found that the volume ratio of template, monomer and crosslinker that produced the highest MIP@GO-Fe3O4 mass is obtained at P3 volume ratio (1:4:8mL, which is further polymerized with GO-Fe3O4 as much as 0.6239g). Swelling ratio studies using 3 (three) solvents namely chloroform, acetone and methanol show that the swelling ratio values obtained are 1.46, 1.24 and 1.23g/g, respectively. These results indicate that methanol is the best solvent for use in the rebinding process of MIP@GO-Fe3O4 material. Based on the analysis by FTIR, XRD, SEM-EDX and BET-BJH, the resulting MIP@GO-Fe3O4 material is expected to be used later for wild p53 preconcentration from various biological samples.

Synthesis and properties of a temperature-sensitive hydrogel based on physical crosslinking via stereocomplexation of PLLA-PDLA.

A synthetic route to amphiphilic conetwork (APCN) gels was developed and involved (1) a ring-opening polymerization (ROP) synthesis of the macromonomer HEMA-PLLA/PDLA, and (2) a radical polymerization of a stereocomplex of the synthesized macromonomers with P(MEO2MA-co-OEGMA) to form the APCN gels. The structure of the gel was successfully verified using X-ray diffraction. Thermal analysis and differential scanning calorimetry data showed that the thermal behaviors of the gels were greatly improved compared with that of polylactic acid (PLA). The mechanical properties of the gels were measured by using a dynamic viscometer, and the results indicated a greater mechanical strength before swelling than afterwards, and an increasing strength of the gels with increasing amount of PLA stereocomplex. Gels placed in different aqueous phases at different temperatures showed different swelling ratio (SR) values. Specifically, the SR gradually decreased as the temperature was increased, indicating a temperature sensitivity of the gels. In addition, the gels placed in the aqueous and organic phases presented as hydrogels and hydrophobic gels, respectively, and their SR values were relatively low. These results indicated the amphiphilic nature of the gel, and indicated great application prospects for the gel in biomedicine.

In Vitro Degradation of Gelatin/carboxymethylcellulose Scaffolds for Skin Tissue Regeneration

The field of tissue engineering has grown in response to many medical needs for tissue replacement. For the skin replacement, there have to develop the different types of tissue engineered skin substitutes. The artificial scaffold have to be a biodegradable material with appropriate degradation rate for skin regeneration. In this study, gelatin blended with carboxymethylcellulose (CMC) scaffold was fabricated via freeze drying method. The various gelatin and CMC ratios were 100/0, 90/10, 80/20, 70/30 and 60/40, respectively. In vitro degradation of the scaffold was done by degradation in lysozyme in PBS buffer within desired time. The swelling ratio of the scaffolds was done by immersing in PBS buffer for 2 h at 37oC. The results revealed that the gelatin/CMC (80:20) scaffold showed the highest value of swelling ratio and have an appropriate degradation rate with completely degraded after 36 h.

Design and performance of a poly(vinyl alcohol)/silk fibroin enzymatically crosslinked semi-interpenetrating hydrogel for a potential hydrophobic drug delivery.

In this study, in order to obtain hydrogels with good properties for sustained release of hydrophobic drugs or for tissue engineering, poly(vinyl alcohol) (PVA)/silk fibroin (SF) semi-interpenetrating (semi-IPN) hydrogels with varied ratios of PVA/SF were enzymatically cross-linked using horseradish peroxidase. A vial inversion test determined approximate gelation times of PVA/SF hydrogels ranging from 5 to 10 min. The hydrogels with varied ratios showed differences in pore size and morphology. Mass loss rate of hydrogels increased from 15% to 58% with increasing PVA concentration. Stable hydrogels with PVA/SF at 0.5 : 1 w/w showed the best swelling ratio values in distilled water (7.36). FTIR analysis revealed that silk fibroin in these hydrogels exhibited the coexistence of amorphous and silk I crystalline structures and the SF and PVA molecules interacted with each other well. The mechanical properties of the composite hydrogels were controlled by the SF content. From the cell viability results, it was found that the hydrogels exerted very low cytotoxicity. Paeonol was chosen as the hydrophobic drug model for release studies from the hydrogels. Paeonol can be uniformly loaded into the composite hydrogels using the emulsifying property of PVA and paeonol release from the hydrogels was dependent on the PVA/SF ratio. This study applied a novel type of enzymatically crosslinked semi-IPN hydrogel that may have potential applications in drug delivery.

Swelling Performance Studies of Acrylamide/Potassium 3-Sulfopropyl Methacrylate/Sodium Alginate/Bentonite Biohybrid Sorbent Hydrogels in Binary Mixtures of Water-Solvent

In this study, it was to investigate the swelling performance of novel biohybrid composite hydrogel sorbents containing acrylamide/potassium 3-sulfopropyl methacrylate/sodium alginate/bentonite in water and binary mixtures of water-solvent. Novel hydrogels were synthesized with free radical solution polymerization by using ammonium persulfate/N,N,N’,N’-tetramethylethylenediamine as redox initiating pair in presence of poly(ethylene glycol) diacrylate as crosslinker. Swelling experiments were performed in water and binary mixtures of water-solvent (acetone, methanol and tetrahydrofuran) at 25°C, gravimetrically. Some swelling and diffusion properties of the hydrogels were calculated and they were discussed for the biohybrid/hybrid hydrogel systems prepared under various formulations. It has been seen the lower equilibrium percentage swelling ratio values (62% - 124%) in all solvent compositions in comparison with the equilibrium percentage swelling ratio values in water (718% - 2055%). Consequently, the hydrogel systems developed in this study could serve as a potential device for water and water-solvent binary mixtures.

Thermo-sensitive and swelling properties of cellouronic acid sodium/poly (acrylamide-co-diallyldimethylammonium chloride) semi-IPN

In current study, cellouronic acid sodium (CAS), obtained from bagasse pith, has been introduced into poly(acrylamide-co-diallyldimethylammonium chloride) (poly(AM-co-DAC)) network to form novel thermo-sensitive semi-IPNs. The structure and morphology of the hydrogels were proved by Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effects of CAS content, initiator charge, cross-linker dosage and swelling-medium property on the thermo-responsive water absorptivity were investigated in detail. The results elucidated that the prepared gels exhibited a thermo-sensibility with an upper critical solution temperature (UCST) and a high water-absorbency. And the values of UCST and equilibrium swelling ratio largely depended on the inner structure of the semi-IPNs and the external solvent property. It was also revealed that the swelling process conformed to the Schott’s pseudo second order model and diffusion type was non-Fickian diffusion. The value of activation energy for this polyelectrolyte was found to be 8.74kJ/mol.

Swelling behavior of poly(n‐butyl acrylate/1,6‐hexane‐diol‐di‐acrylate)/nematic liquid crystalE7 systems: Experimental measurements and modeling by factorial design method

ABSTRACTThe swelling process of poly(n‐butyl acrylate/1,6‐hexane‐diol‐di‐acrylate) [Poly(Abu/HDDA)] networks, immersed in a liquid crystalline (LC) solvent, was investigated in order to obtain improved swelling ratio values upon application of an original method using a central composite design. The polymer/LC systems under investigation were elaborated via a photopolymerization/crosslinking phase separation process induced by UV radiation of initial mixtures composed of mono‐ and bifunctional monomers, a photoinitiator, and the low‐molar‐weight nematic LC blend E7. The parameters which strongly impact the swelling behavior of Poly(Abu/HDDA)/E7 systems were identified as temperature and concentration of the bifunctional monomer in the initial photopolymerizable mixture, thus controlling the crosslinking density of the final polymer network. The existence of interactions and synergies between these two parameters were also examined. The quality of the model was verified by a good agreement between experimental results and predicted response. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2017,134, 45230.

Effect of Polyvinyl Acetate Stabilization on the Swelling-Shrinkage Properties of Expansive Soil

Polyvinyl acetate constitutes a class of polymers that can entirely dissolve in water to form a solution. In this study, polyvinyl acetate as a nontraditional chemical stabilizer was used in soil improvement. Laboratory tests were carried out to evaluate the effect of polyvinyl acetate on swelling-shrinkage properties of expansive soil. A series of shrink/swell tests were performed with adding polyvinyl acetate as amendment at a concentration 3 g/cm3 to four aggregate sizes in the range of 0–0.5 mm, 0.5–1 mm, 1-2 mm, and 2–5 mm and five concentrations 1.5 g/cm3, 3 g/cm3, 4.5 g/cm3, 6 g/cm3, and 9 g/cm3 to soils with aggregate size in the range of 0.5–1 mm for comparison of results with those of untreated soils. The results show that all the linear swelling ratio (LSWR) and linear shrinkage ratio (LSHR) values of the treated specimens decrease. SEM images and the test results indicate the achieved reduction in volume change of the soil tested using soil pore filling and particle encapsulation.

Broadband absorption spectroscopy for rapid pH measurement in small volumes using an integrated porous waveguide.

Broadband absorption spectroscopy integrated with microfluidics is widely used to measure the pH of samples available in small volumes. Single pass absorption spectroscopy, however, suffers from poor minimum detectable absorption coefficient because the optical path length is determined by the physical dimensions of microchannels. As a result, either large amounts of indicator dyes are added or instrumentally complex techniques are used to determine sample pH. This work addresses these limitations by the integration of metal-clad leaky waveguide (MCLW) with microfluidics to perform broadband absorption spectroscopy. The MCLW consisted of a porous agarose waveguide with an estimated thickness and swelling ratio values of 1.405 ± 0.009 μm and 20.96 ± 0.65% respectively coated onto a titanium layer 32.8 ± 0.43 nm thick on a glass slide. MCLW permits obtaining absorption spectra over most of the wavelength range of the visible region (i.e. 450 nm to 700 nm) with a speed of 12.5 spectra per second using 3.2 nl of sample. The minimum detectable decadic absorption coefficient measured using MCLW was 0.43 cm-1, which is intermediate between single pass absorption spectroscopy and instrumentally complex techniques such as broadband cavity enhanced absorption spectroscopy and whispering gallery mode resonators.