Papers by Keyword: Hydroxyl

Abstract: Preparation of telechelic hydroxyl low molecular weight fluoropolymers by reduction reaction was presented. The telechelic carboxyl low molecular weight fluoropolymers were chosen as raw materials which were prepared by oxidative degradation method. The molecular weights of telechelic carboxyl low molecular weight fluoropolymers were about 3700. Then, using lithium aluminum hydride reacted with carboxyl groups to prepare the telechelic hydroxyl low molecular weight fluoropolymers. The effects of reaction temperatures, reaction times, contents of solvent and lithium aluminum hydride were investigated in detail. The structures, Mn and dynamic viscosity of low molecular weight fluoropolymers were analyzed by FTIR, ¹H-NMR, GPC and viscometer respectively. Finally telechelic hydroxyl low molecular weight fluoropolymers were prepared. The conversion rate of that reduction reaction was about 95%. The product was a viscous fluid with a dynamic viscosity of 48Pa·s at 50°C.

Abstract: In present study, in vitro antioxidant activities of polysaccharide from Agaricus bisporus mycelia (PABM) were evaluated using 1,1-diphenyl-2-picrylhydrazy (DPPH), hydroxyl (ˑOH) and superoxide anion (ˑO₂^-) radicals scavenging activities. The results indicated that PABM could significantly scavenge DPPH, hydroxyl and superoxide anion radicals. Thus, PABM can be used as natural antioxidants in functional foods or medicine.

Abstract: Paulownia tomentosa Steud flowers have been used for many therapeutic purposes in traditional pharmacopeia. The components of the extract of Paulownia tomentosa Steud flowers were separated using ethanol elution. The antioxidant properties of different components (20% component, 40% component, 60% component, and 80% component) and synthetic antioxidants (BHA and BHT) were evaluated by scavenging DPPH, superoxide anions, and hydroxyl radical methods. All components showed strong antioxidant properties, especially the 60% component, which exhibited excellent antioxidant activity. These components may be developed for use as natural antioxidants. The main compounds in these components were identified using UPLC-TOF-MS/MS and UV spectra analysis. Two compounds, abscisic acid and t-abscisic acid, were found in the 20% component. Five compounds, t-abscisic acid, luteolin, apigenin, tricin, and 4′,5,7-trihydroxy-3′-methoxyflavone, were found in the 40% component. Three compounds, t-abscisic acid, apigenin and 4′,5,7-trihydroxy-3′-methoxyflavone, were found in the 60% component. Six compounds, luteolin, apigenin, 4′,5,7-trihydroxy-3′-methoxyflavone, paulownin, 3'-methyldiplacol, and diplacone, were found in the 80% component. The antioxidant activity of these components can be attributed to the main chemical composition of the components of the extract of Paulownia tomentosa Steud flowers.

Abstract: The aim of this paper is to discuss on the roles of plant extract in the synthesis of metallic nanoparticles. Synthesis of metallic nanoparticles has started few decades ago through physical and chemical methods. Recently, green technology through biosynthesis method has drawn great attention compared to the physical and chemical method. Biosynthesis was found to be more energy efficient and able to eliminate the use of hazardous chemicals. The biosynthesis studies involved the application of fungi, bacteria, yeast, algae and plant extract. Plant extract has several advantages since the use of microorganism required stringent control on cell culture. Furthermore, the reaction rate is much faster as compared to that of the microorganism methods. The important compounds in the plant extract are hydroxyl and carbonyl groups. Both functional groups allowed plant extract to act as reducing agent as well as stabilizing agent. Several studies have been carried out to optimize the extraction of these compounds such as plant drying technique, extraction temperature and type of extractions solvent. The common method used to quantify the concentration of reducing agents in the extract is through Folin-Ciocalteu method. Utilization of plant extract not only capable of producing well dispersed monometallic nanoparticles, but also bimetallic nanoparticles. Previous studies revealed that concentration of plant extract has significant effect on particle size and shape as well as particle distribution.

Abstract: Human demineralized bone matrix (DBM) containing bone morphogenetic proteins (BMPs) is naturally biocompatible and can be remodeled by patients’ own bone. The major shortcoming of many of the currently used DBM gel formulations is that they have a tendency to flow, particularly if there is continuous bleeding at the application site. In this study, the physicochemical properties of human DBM were examined to improve the efficiency of DBM formulations. DBM remarkably showed higher water absorption than nondemineralized bone powder after 150 min. Hydroxyl groups in DBM appeared in fourier transform infrared analysis, although hydroxyl band in nondemineralized bone powder was not observed. The results suggested that hydrogels such as CMC, hyaluronic acid, or poloxamer as carriers can be applied for injectable DBM products, such as gel or putty types.

Abstract: The carboxyl modified carbon nanotubes were obtained by treating them in the concentrated nitric acid with a little surfactant. The complete electrochemical combustion of phenol has been found under 5 M at the carboxyl modified carbon nanotube electrode in phosphate buffer solution. The reaction was discussed in details. Due to the porous tubule of the structure of the carbon nanotube and large quantity of hydroxyl exists in the carboxyl modified carbon nanotube electrode, which were necessary for the continually electrochemical combustion of phenol. Long time potentiostatic oxidation showed that the phenol could be eliminated from the aqueous media without any foul at the carbon nanotube electrode.