| Separation and detection of mutans streptococci by using magnetic nanoparticles stabilized with a cell wall binding domain-conjugated polymer | |
| Thanyasrisung P., Vittayaprasit A., Matangkasombut O., Sugai M., Na Nongkai P., Saipia S., Hoven V.P. | |
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| Abstract | |
| A number of salivary mutans streptococci (MS: Streptococcus mutans and Streptococcus sobrinus) are used in dental caries risk assessment. In this study, a simple, yet effective assay was developed for MS detection. Magnetic nanoparticles (MNPs) were first grafted with poly(acrylic acid) that bears active carboxyl groups available for conjugation with the cell wall binding domain (CWBD) of automutanolysin which specifically binds to MS. The binding efficiency of CWBD-conjugated MNPs to MS was tested with pure cultures of streptococcal standard strains. After mixing CWBD-conjugated MNPs with culture, bacteria-bound particles were separated from unbound cells using a magnet and filtered through a cellulose acetate membrane (pore-size 0.8 μm). The color intensity of particles remaining on the membrane represents the number of bound bacteria. The CWBD-conjugated MNPs showed higher efficiency in binding to S. mutans and S. sobrinus than to non-mutans streptococci (S. sanguinis and S. salivarius) with capture efficiencies of 77 and 69% for MS and 38 and 15% for non-MS. Moreover, this method can quantify the number of MS in the range of 102 to 107 colony-forming units (CFU) mL-1, which covers the range of MS levels used in caries risk assessment. The calculated limit of detection of the assay was 16 and 72 CFU mL-1 for S. mutans and S. sobrinus, respectively. Furthermore, the CWBD-conjugated MNPs could be used to efficiently quantify the number of MS in human saliva samples containing highly complex mixtures of bacterial species. These results suggest that the assay could be applicable as a simple tool for MS determination in not only clinical settings but also community fields without clinical expert requirement. © 2018 The Royal Society of Chemistry. | |
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| Bacteria; Efficiency; Nanomagnetics; Nanoparticles; Pore size; Risk assessment; Cell wall-binding domain; Colony forming units; Limit of detection; Magnetic nano-particles; Magnetic nanoparti cles (MNPs); Mutans streptococci; Poly(acrylic acid ); Streptococcus mutans; Conjugated polymers; Bacteria; Binding; Detection; Efficiency; Particles; Pore Size; Risk Assessment; Walls | |
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| Solution processed blue-emitting and hole-transporting materials from truxene-carbazole-pyrene triads | |
| Wongsilarat C., Namuangruk S., Prachumrak N., Sudyoadsuk T., Promarak V., Sukwattanasinitt M., Rashatasakhon P. | |
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| Abstract | |
| A new series of truxene derivatives containing different numbers of dipyrenylcarbazole substituents are prepared and evaluated as emissive and hole-transporting layers in electroluminescent devices. The compounds are synthesized from Cu-catalyzed C-N coupling between the iodotruxene core and 3,6-dipyrenylcarbazole and characterized by 1H NMR, 13C NMR and MALDI-TOF mass spectroscopy. These compounds exhibit strong fluorescence in the blue region and show excellent thermal stabilities with Td 10% above 440 °C. They are tested as non-doped blue emitters in the OLEDs with the structure of ITO/PEDOT:PSS/EML/BCP/LiF:Al. The derivative containing two dipyrenylcarbazole moieties exhibits the highest maximum brightness of 8.0 × 103 cd/m2 at 9.6 V with a low turn-on voltage (Von) of 3.4 V. In the devices of structure ITO/PEDOT:PSS/HTL/Alq3/LiF:Al, the compound also shows superior hole-transporting properties in comparison with the standard compound (N,N′-Bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine). The device fabricated from this compound as the HTL shows the highest maximum brightness of 4.5 × 104 cd/m2 at 10.8 V with a low turn-on voltage (Von) of only 2.8 V. © 2018 Elsevier B.V. | |
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| Copper compounds; Electroluminescence; Hole mobility; Luminance; Mass spectrometry; Optoelectronic devices; Pyrene; Carbazole; Hole transporting; Hole transporting layers; Hole-transporting materials; Hole-transporting property; Low turn-on voltages; MALDI-TOF mass spectroscopy; Truxene; Aluminum compounds | |
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| Hexabromoacetone: An efficient reagent for bromination of saturated hydrocarbons catalyzed by oxidovanadium(IV) picolinate complex | |
| Pongpipatt P., Saroachsoontornkul S., Chavasiri W. | |
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| Abstract | |
| The efficient brominating agent, hexabromoacetone (HBA) worked very well with oxidovanadium(IV) picolinate catalyst in selective bromination of saturated hydrocarbons with no competing C–H oxidation. Cyclododecyl bromide was fruitfully obtained as a major product from the bromination of cyclododecane with trace amount of oxidized product(s). The selectivity attained for the reaction was excellent. Competitive bromination using selected alkane and alcohol revealed that alkyl bromide occurred via alkane substrate directly. © 2018 Elsevier B.V. | |
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| Paraffins; Alkyl bromides; Brominating agents; Bromination; Cyclododecane; Hexabromoacetone; Oxidized products; Oxidovanadium complex; Saturated hydrocarbons; Hydrocarbons | |
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| Poly(butyl acrylate-co-fluorinated acrylate)-graft-natural rubber: Synthesis and application as compatibilizer for natural rubber/poly(butyl acrylate-co-fluorinated acrylate) films | |
| Yimmut K., Homchoo K., Hinchiranan N. | |
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| Poly(butyl acrylate-co-fluorinated acrylate)-graft-natural rubber was successfully prepared via emulsion graft copolymerization and applied as a compatibilizer for improving phase compatibility and toughness of natural rubber/poly(butyl acrylate-co-fluorinated acrylate) films. From graft copolymerization step, butyl acrylate (BA) acted as a co-monomer to be initially grafted onto the natural rubber (NR) and then copolymerized with 2,2,2–trifluoroethyl methacrylate (3FMA) to form a grafting poly(BA-co-3FMA) chain onto the NR backbone. The appropriated BA/3FMA ratio at 30/70 (w/w) provided the highest graft copolymer fraction of 72.8 wt% with 25.3 mol% grafted 3FMA and 68.5% grafting efficiency under center reaction condition. Transmission electron microscopy analysis indicated that the graft product had core-shell morphology, which NR was a core and covered by poly(BA-co-3FMA) shell. The results from Molau test and atomic force microscopy showed that the addition of 5–10 wt% graft product could enhance the compatibility between NR and poly(BA-co-3FMA) phases in the NR/poly(BA-co-3FMA) films (20/80 (w/w)) and provided the obtained films with a greater elongation at break to 266% than that of poly(BA-co-3FMA) film (27%). The compatibilized films also exhibited a high hydrophobicity (water contact angle = 109°) and oleophobicity (hexadecane contact angle = 54°) with a low surface energy (8.04 mN/m), which can be further applied as self-sealing films for moisture and oil protection. © 2017 Elsevier B.V. | |
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| Atomic force microscopy; Contact angle; Copolymerization; Emulsification; High resolution transmission electron microscopy; Mechanical properties; Rubber; Rubber films; Surface properties; Transmission electron microscopy; Butyl acrylates; Core-shell morphologies; Fluorinated acrylate; Graft co polymerizations; Natural rubber latex; Reaction conditions; Transmission electron; Trifluoroethyl methacrylates; Grafting (chemical); acrylic acid butyl ester; copolymer; hexadecane; latex; methacrylic acid derivative; poly(butyl acrylate co fluorinated acrylate); rubber; unclassified drug; Article; atomic force microscopy; concentration (parameters); contact angle; controlled study; emulsion; fluorine nuclear magnetic resonance; hydrophobicity; molecular weight; morphology; polymerization; priority journal; proton nuclear magnetic resonance; reaction analysis; reaction time; surface property; synthesis; temperature sensitivity; tensile strength; transmission electron microscopy | |
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| Utilization of hexabromoacetone for protection of alcohols and aldehydes and deprotection of acetals, ketals, and oximes under UV irradiation | |
| Chaiseeda K., Chantharadet L., Chavasiri W. | |
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| Hexabromoacetone (HBA) was efficiently used for the protection of alcohols and aldehydes and deprotection of benzaldehyde dimethyl acetal, solketal, and other acetals and ketals. In only 10 min, the protection of glycerol yielded 90% of solketal and protection of benzaldehyde gave 95% of benzaldehyde dimethyl acetal. The deprotection of benzaldehyde dimethyl acetal under UV irradiation gave over 90% yield of benzaldehyde within 15 s using only 2.5 mol% of HBA. HBA was also successfully used for deoximation. Solvent was found to play an important role in the efficiency of HBA for these reactions. © 2017, Springer Science+Business Media B.V. | |
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| Aldehydes; Glycerol; Acetal; Deprotection; Diol; Hexabromoacetone; Ketal; Oxime; Protection; Solketal; Irradiation | |
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| Poly(lactic acid)/poly(vinyl alcohol)/graphene nanocomposites | |
| Rattanakot J., Potiyaraj P. | |
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| Abstract | |
| Poly(lactic acid) (PLA) is an interesting material as an environmentally-friendly replacement of petroleum-based polymers. However, some properties need improvements in order to commercially utilized PLA. In this work, graphene is used as a reinforcing filler and poly(vinyl alcohol) is used as a carrier to enhance dispersion of graphene in PLA matrix. The addition of graphene aims at improving the mechanical and thermal properties of PLA. The functional groups of graphene were characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The mechanical property testing was performed using a universal testing machine. The thermal properties were measured through differential scanning calorimetry (DSC). As a result, the Young’s modulus and the thermal properties of PLA composites increased as the amount of graphene in the composites increased due to improved dispersion of graphene in PLA matrix. © 2018 Trans Tech Publications, Switzerland. | |
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| Differential scanning calorimetry; Dispersions; Elastic moduli; Fourier transform infrared spectroscopy; Lactic acid; Mechanical properties; Polyvinyl alcohols; Thermodynamic properties; Mechanical and thermal properties; Mechanical property testing; Poly lactic acid; Polylactic acids; Polymer composite; Reinforcing fillers; Universal testing machines; Vinylalcohol; Graphene | |
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| Effect of the blow-up ratio on morphology and engineering properties of three-layered linear low-density polyethylene blown films | |
| Auksornkul S., Soontaranon S., Kaewhan C., Prasassarakich P. | |
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| A series of linear low-density polyethylene films were produced using a three-layer co-extrusion machine. How the blow-up ratio and resin characteristics affected the final film morphology and engineering properties were studied. The crystalline morphology and orientation during the blown film process of the low-density polyethylene film were investigated using small-angle X-ray scattering, transmission electron microscopy and scanning electron microscopy. Increasing the blow-up ratio increased the transverse direction molecular orientation and decreased the machine direction orientation. The resulting low-density polyethylene morphology was a regular lamellar stacking parallel to the machine direction. The film morphology strongly influenced the mechanical properties. Increasing the blow-up ratio from 1.7 to 2.8 decreased the machine direction tensile strength by 14% and increased the transverse direction tensile strength up to 27% for both the low-density polyethylene/1-butene and low-density polyethylene/1-octene co-monomers, while the machine direction tear strength increased up to 36% and the transverse direction decreased by 16%. Moreover, the first and second heating characteristics from differential scanning calorimeter showed the inherent crystallinity change with increasing blow-up ratio for both the low-density polyethylene/1-octene and the low-density polyethylene/1-butene copolymer. The crystalline orientation changes induced with increasing blow-up ratio affected the film water vapor and oxygen permeability. © 2017, © The Author(s) 2017. | |
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| Crystalline materials; Differential scanning calorimetry; Electron microscopy; High resolution transmission electron microscopy; Linear low density polyethylenes; Molecular orientation; Morphology; Scanning electron microscopy; Tensile strength; Transmission electron microscopy; X ray scattering; Blow-up ratios; Blown-films; Crystalline morphologies; Crystalline orientations; Differential scanning calorimeters; Engineering properties; Low density polyethylene films; Machine direction orientation; Polyethylenes | |
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