• Advances in environmental research
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• v.2 no.1
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• pp.35-49
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• 2013

Research work on removal of fluoride from water, referred to as water defluoridation, has resulted into the development of a number of technologies over the years but they suffer from either cost or efficiency drawbacks. In this work, enhancement effects of phosphate and silicate on defluoridation of water by low-cost Plaster of Paris (calcined gypsum) were studied. To our knowledge, the influence of silicate on defluoridation was not reported. It was claimed, that the presence of some ions in the treated water samples, was decreasing the fluoride removal since these ions compete the fluoride ions on occupying the available adsorption sites, however, phosphate and silicate ions, from its sodium slats, have enhanced the fluoride % removal, hence, precipitation of calcium-fluoro compounds of these ions can be suggested. Percentage removal of $F^-$ by neat Plaster is 48%, the electrical conductance (EC) curve shows the typical curve of Plaster setting which begins at 20 min and finished at 30 min. The addition of phosphate and silicate ions enhances the removal of fluoride to high extent > 90%. Thermodynamics parameters showed spontaneous fluoride removal by neat Plaster and Plaster-silicate system. The percentage removal with time showed second-order reaction kinetics.

• Polymer(Korea)
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• v.30 no.5
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• pp.402-406
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• 2006

New antibacterial Polyurethane foams for car seat with Urushiol extracted from a natural lacquer were prepared. Influences of antibacterial agent's concentration on the reactivity with isocyanate and the mechanical properties of foams were investigated. It was observed that the urethane formation reaction was delayed a little when the amount of Urushiol was increased. However, the foams made using Urushiol showed similar property to the neat polyurethane foam. In terms of antibacterial property, the foams prepared with Urushiol showed better performance than the neat polyurethane foam.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.899-904
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• 2011

A series of 5-indolylpyrimido[4,5-d]pyrimidinones (4a-h) were obtained by multi-component reaction of 3-formylindole (1), thiobarbituric acid/barbituric acid (2) and thiourea/urea (3) under microwave irradiation in dry media. Secondly, grinding together neat reactants also gave the titled compounds in good yields. All the synthesized compounds have been characterized on the basis of elemental analyses and spectral data (IR, $^1H$ NMR and Mass). Representative compounds were also evaluated for their antimicrobial activity against Rhizopus stolonifer, Fusarium oxysporum, Escherichia coli, and Pseudomonas aeruginosa at different concentrations. Some of the compounds showed promising activity.

• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.340-344
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• 1998

A facile synthesis of 4,5-(1',2'-diphenylethylenedithio)-1,3-dithiole-2-thione (dPhEDT-DTT) is carried out via a Diels-Alder type [2+4] cycloaddition reaction of 1,3-dithiol-2,4,5-trithione oligomer and t-stilbene. Molecular structure of dPhEDT-DTT is determined by x-ray crystallography: space group P1, a=11.694(3) Å, b=12.117(3) Å, c=14.688(3) Å, α=113.12(2)°, β=102.23(2)°, γ=107.02(2)°, V= 1699.1(7) Å3, Z=2. It turns out that dPhEDT-DTT crystallizes as a racemic compound consisting of (R,R) and (S,S) enantiomers. Coupling reaction of dPhEDT-DTO undergone in neat P(OEt)3 yields TTF(SEt)4 instead of ET derivative. When PR3 (R=OEt, OPh, Ph) is used in benzene, toluene or xylene, however, dPhEDT-DTO is decomposed.

• Macromolecular Research
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• v.11 no.4
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• pp.267-272
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• 2003

The isothermal cure reactions of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer (poly(dimmer acid-co-alkyl polyamine)) or PEI were studied using differential scanning calorimetry (DSC). Rheological measurements have been made to investigate the viscosity and mechanical relaxation behavior of the blends. The reaction rate and the final cure conversion were decreased with increasing the amount of thermoplastics in the blends. Lower values of final cure conversions in the epoxy/thermoplastic blends indicate that thermoplastics hinder the cure reaction between the epoxy and the curing agent. Complete miscibility was observed in the uncured blends of epoxy/thermoplastics up to $120^{\circ}C$ but phase separations occurred in the early stages of the curing process at higher temperatures than $120^{\circ}C$. According to the rheological measurement results, a rise of G' and G" at the onset of phase separation is seen. A rise of G' and G" is not observed for neat epoxy system since no phase separation is seen during cure reaction. At the onset of phase separation the rheological behavior was influenced by the amount of thermoplastics in the epoxy/thermoplastic blends, and the onset of phase separation can be detected by rheological measurements.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.9
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• pp.1247-1255
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• 2016

Heparin binding proteins (HBPs) are produced by accessory glands. These are secreted into the seminal fluid, bind to the spermatozoa at the time of ejaculation, favour capacitation, acrosome reaction, and alter the immune system response toward the sperm. The present study was conducted with an objective to assess the effect of purified seminal plasma-HBPs (SP-HBPs) on cross bred cattle bull sperm attributes during two phases of cryopreservation: Pre freezing and freezing-thawing. SP-HBPs were purified from pooled seminal plasma by heparin affinity chromatography. Three doses of SP-HBPs i.e. 10, 20, $40{\mu}g/mLs$ semen were standardized to find out the optimum dose and $20{\mu}g/mLs$ was found to be an optimum dose. Semen as such and treated with SP-HBPs was diluted with sodium citrate-egg yolk diluter and cryopreserved as per the standard protocol. Sperm parameters i.e. motility, viability, Hypo-osmotic swelling test (HOST), acrosome damage, in vitro capacitation and lipid peroxidation were evaluated in SP-HBP treated and untreated (control) semen at both phases of cryopreservation. A considerable variation in percent sperm motility, viability, membrane integrity (HOST), acrosome damage, acrosome reaction and lipid peroxidation was observed at both phases among the bulls irrespective of the treatment. Incubation of neat semen with $20{\mu}g/mL$ SP-HBP before processing for cryopreservation enhanced the average motility, viability, membrane integrity by 7.2%, 1.5%, 7.9%, and 5.6%, 6.6%, 7.4% in pre-frozen and frozen-thawed semen in comparison to control. There was also an average increase of 4.1%/3.9% in in vitro capacitation and acrosome reaction in SP-HBPs-treated frozen-thawed semen as compared to control. However, binding of SP-HBPs to the sperm declined acrosome damage and lipid peroxidation by 1.3%/4.1% and 22.1/$32.7{\mu}M$/$10^9$ spermatozoa in SP-HBP treated pre-frozen/frozen-thawed semen as compared to control, respectively. Significant (p<0.05) effects were observed only in motility, HOST and in vitro acrosome reaction. It can be concluded that treatment of neat semen with SP-HBPs before cryopreservation minimized the cryoinjury by decreasing the generation of reactive oxygen species.

• Analytical Science and Technology
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• v.9 no.3
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• pp.292-301
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• 1996

The synthesis of poly(ether)tailed bipyridine complex as redox reaction probes has advanced attempts to interpret very slow diffusion and heterogeneous electron transfer. Diffusion coefficients as low as $1.5{\times}10^{-15}cm^2/s$ have been observed for the oxidation of neat $Co(bpy(ppgm)_2)_{3^-}(ClO_4)_2$ with $LiClO_4$ electrolyte. Heterogeneous electron transfer rate constants of materials were found to vary with diffusion coefficient. The decrease in k as the diffusion coefficient decreases was actually caused by the decreasing D. Diffusion coefficient for compound of strong ion pairing anion($ClO{_4}^-$) was much smaller than the diffusion coefficient for compound of weak ion pairing anion($CF_3COO^-$).

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.239-246
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• 2008

In this study, the influence of reaction temperatures, mixing time and flexible modifier for crumb rubber modified asphalt(CRMA) as processing conditions were investigated. The temperature susceptibility and adhesion properties of neat and modified asphalts at low temperature measured using the penetration and tensile adhesion test. It was found that processing temperatures and flexible modifier were important factors for tensile adhesion strength and toughness energy at low temperature. The CRMA in the higher processing temperature and flexible modifier exhibited improved tensile adhesion properties which indicated the flexible structure of neat and modified asphalt binder. In general, the improvements of the physical properties in the CRMAs were due to the improvements of miscibility between CR and asphalt binder. It was found that the adhesion properties of the flexible agent modified CRMA were higher than CRMA were related to the flexible agent tend to penetrate into CR particles and asphalt binder.

• Polymer(Korea)
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• v.37 no.2
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• pp.232-239
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• 2013

A series of novel imidazole-blocked diisocyanate bioadhesives (IBAs) were synthesized from reaction of toluene 2, 4-diisocyanate (TDI), isophorone diisocyanate (IPDI), hydroxyl-terminated polylactide (HO-PLA-OH), 1,1,1-trimethylolpropane (TMP), and imidazole. Synthesis of IBAs was confirmed by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) revealed that the TDI-based IBA had lower thermal dissociation temperature and a faster deblocking rate than IBA based on IPDI. Hydroxyl-terminated polyurethane (HPU) was introduced to study the adhesive effect of the synthesized IBAs. Improvement on elastic modulus, tensile strength and water resistance of IBA-modified HPU in comparison with neat HPU suggested the good adhesive effect of IBA due to the strong chemical reaction between released NCO groups from IBA and hydroxyl groups from HPU.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.147-150
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• 2002

The cure kinetics of blends of epoxy (DGEBA:diglycidyl ether of bisphenol A)/anhydride (NMA:nadic methyl anhydride) resin with synthesized amino terminated polyetherimide (AT-PEI) were studied using differential scanning calorimetry (DSC) and Dynamic Mechanical Analysizer(DMA) under isothermal condition to determine the reaction parameters and gel-vitrification behavior. The fracture toughness of AT-PEI 20phr/epoxy resin system was improved over 224% and 42.5% more than neat epoxy resin and commercial PEI/Epoxy Resin System.