Facile synthesis of self-stabilized polyphenol nanoparticles

We describe here the facile synthesis (in two-steps) of green light emitting phenol polymer with an azomethine side group. For this purpose, hydroxy functionalized-Schiff base monomer, HPMBT, was obtained by condensation of 2,3,4-trihydroxybenzaldehyde with 2-aminophenol. Subsequent oxidation of the monomer in alkaline medium by NaOCl yielded to corresponding phenol polymer (PHPMBT) with molecular weight ca. 34,500 Da. The characterizations were performed by NMR, FT-IR, UV–vis, gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), cyclic voltammetry (CV), photoluminescence (PL), dynamic light scattering (DLS) and scanning electron microscope (SEM) analysis. PL analysis indicated that HPMBT was non-fluorescent whereas PHPMBT was a green light emitter. In addition, the redox behaviors of the polymer were explored by cyclic voltammetry (CV), assigned it's electroactive nature. The formation of nano-sized polyphenol particles was revealed by the SEM and DLS analyses. A possible mechanism for the formation and self-stabilization of the polyphenol nanoparticles was also suggested.     

Microstructural development of woven mullite fibre-reinforced mullite ceramic matrix composites by infiltration processing

Mullite fibre (Nextel 720?)-reinforced mullite ceramic matrix composites (CMCs) with zirconia weak interface were fabricated from heterocoagulated nano-size boehmite/amorphous silica powder particles dispersed in water, using electrophoretic deposition (EPD) and pressure filtration (PF). The nano-size mullite precursor was first prepared and characterised in terms of short-range particle–particle interactions and particle size distribution. Woven Nextel 720 mullite fibres were first desized and then coated with hydrothermally derived zirconia using dip-coating. EPD was performed under constant voltage conditions with varying deposition times, to infiltrate the dispersed powder suspensions into mullite fibre preforms, enabling the parameters necessary for good deposition of stoichiometric mullite to be established. EPD formed bodies were further consolitated using PF. The EPD/PF prepared green body specimens were dried under controlled atmosphere conditions before being sintered at 1200°C for 2 h in air. Mullite fibre mats were fully infiltrated using EPD parameters of 12 V DC applied voltage with 4 min deposition time, then eight EPD infiltrated fibre mats were further consolidated together using PF. The resulting CMC produced contained 35 vol% fibre loading and showed 81% theoretical density aftersintering at 1200°C for 2 h.     

Comparative evaluation of oxidative enzyme activities during adventitious rooting in the cuttings of grapevine rootstocks

BACKGROUND: This study investigated changes in peroxidase (POX) and polyphenol oxidase (PPO) activities through adventitious rooting in hardwood cuttings of grapevine rootstocks. Three grapevine rootstocks with different propensity to produce adventitious roots were selected: recalcitrant (Ramsey), non‐recalcitrant (Rupestris du Lot) and intermediate (99R) cultivars. RESULTS: The averages of root number at 65 days were 96 in Lot, 76 in 99R and 30 in Ramsey. Both enzyme activities characteristically increased before adventitious rooting, regardless of rooting ability of the rootstocks, and then decreased. POX activity increased in Ramsey cuttings at 22 days, in Lot and 99R cuttings at 14 days after planting, and then decreased gradually until 51 days. The highest POX activity was determined in Ramsey rootstock with the highest rooting ability and the lowest activity was determined in the rootstocks with the lowest rooting ability. PPO activity gradually increased in Ramsey rootstock cuttings from 10 days to 22 days, in Lot and 99R cuttings at 14 days, and then decreased until 51 days. A significant correlation was identified between high POX activity and adventitious rooting capability in rootstocks, but the same result was not determined with PPO activity. CONCLUSION: A recalcitrant rooting variety cannot increase POX activity sufficiently before rooting. Therefore applications that could increase POX activity in stem cuttings during rooting may facilitate increased rooting in such rootstocks. Copyright © 2011 Society of Chemical Industry     

A new Schiff base epoxy oligomer resin: Synthesis,characterization, and thermal decomposition kinetics

Oligo{2,2′‐{1,4‐phenylenebis[nitrilomethylylidene]}bis(6‐methoxyphenol)} (OPNMMP) was synthesized from o‐vanillin and p‐phenylene diamine by oxidative polycondensation with NaOCl in an aqueous alkaline. Then, a new Schiff Base epoxy oligomer resin, OPNMMP–epichlorohydrine (EPC), was produced with EPC. The structures of the resulting compounds were confirmed by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, ¹H‐NMR, and ¹³C‐NMR. Further characterization processes were preformed by thermogravimetry (TG)–differential thermal analysis, gel permeation chromatography, and solubility testing. Also, the kinetics of the thermal decomposition of OPNMMP–EPC were investigated by thermogravimetric analysis. The TG curves showed that the thermal decomposition of OPNMMP–EPC occurred in one stage. The kinetic parameters related to the decomposition kinetics of OPNMMP–EPC were obtained from TG curves with the following methods: Friedman, Flynn–Wall–Ozawa, Kissinger, invariant kinetic parameter, and Coats–Redfern (CR), under an N₂ dynamic atmosphere and different heating rates (5, 10, 15, and 20°C/min). The mechanism function and pre‐exponential factor were also determined by a master plots method. The apparent activation energies of the thermal decomposition were calculated from these methods for OPNMMP–EPC. The analysis of the results obtained by the CR and master plots methods showed that the decomposition mechanism of OPNMMP–EPC in N₂ was a deceleration‐type mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of the new pyridine‐containing poly(azomethine‐urethane)s: The effect of methyl substituent as electron‐donating group on some physical properties

In this study, a series of pyridine‐ring based poly(azomethine‐urethane)s were synthesized to investigate the effect of electron‐donating group on some physical properties such as thermal stability, optical, and electrochemical properties. For this reason, firstly the Schiff bases were synthesized using amino‐methyl pyridines (2‐amino‐3‐methyl pyridine, 2‐amino‐4‐methyl pyridine, and 2‐amino‐6‐methyl pyridine) with 2,4‐dihydroxy benzaldehyde by the condensation reaction. Then, these Schiff bases were converted to poly(azomethine‐urethane) derivatives via step‐polymerization reaction. Secondly, structural characterizations were carried out by FTIR, NMR, and UV–Vis. Cyclic voltammetry was used to determine the electrochemical oxidation‐reduction characteristics. Optical properties were investigated by UV–vis and fluorescence analyses. Thermal properties were clarified by TG‐DTA and DSC techniques. The molecular weight distributions of polymer were determined by size exclusion chromatography. POLYM. ENG. SCI., 54:1664–1674, 2014. © 2013 Society of Plastics Engineers     

UV curable coatings for improved gas barrier properties of poly(ethylene terephthalate)

A new high-barrier coating based on methyl (α-hydroxymethyl)acrylate (MHMA) for poly(ethylene terephthalate) (PET) was developed along with the process for preform dipping and cure prior to blow molding into bottles. The UV curable coating gives excellent gas barrier improvement when coated onto PET biaxially oriented thin films. Blown bottle side walls from coated PET preforms also show 2–3 times improvement over uncoated side walls. The effect of photoinitiator concentration, initiator types, and temperature on photopolymerization kinetics of MHMA was investigated. Once the photoinitiator, Irgacure 819^®, concentration became larger than 1 mol%, a decrease in rate of propagation was observed. The conversion also decreased with higher initiator concentration. Irgacure 819^® reduced the auto-acceleration peak and reached maximum rates of polymerization much faster than Irgacure 651^®. It also gave a slightly higher conversion. Overall conversion for combinations of these photoinitiators was high, above 80%. Real-time FTIR (RT-FTIR) studies of copolymerization of MHMA and methyl methacrylate (MMA) showed that conversion was fairly high up to 25 mol% MMA. However, once MMA feed ratio exceeded 10 mol%, a decrease in barrier performance was observed.     

Effect of Commercial Starter Cultures on the Myofibrillar Proteins of Pastirma, a Turkish Dry Meat Product

ABSTRACT: The effect of 3 different commercial starter cultures ( Staphylococcus carnosus, Staphylococcus carnosus + Lactobocillus pentosus and Staphylococcus xylosus + Lactobacillus sakei ) on the myofibrillar proteins of pastirma was investigated. It was observed that using commercial starter cultures in pastirma manufacture had a significant effect on myofibrillar fragmentation. However, the effect of each starter culture on myofibrillar fragmentation in pastirma was different. Most of the changes in myofibrillar proteins were produced with S. carnosus + L. pentosus.     

Effect of dietary humate on the pH,TBARS and microbiological properties of vacuum‐ and aerobic‐packed breast and drumstick meats of broilers

The current trial determined the influence of dietary humate, including humic, fulvic and ulmic acids and some microminerals on the pH, TBARS and microbiological properties of vacuum‐packed and aerobic‐packed breast fillets and drumsticks of broilers. A total of 240 male broiler chicks (Ross‐308) were randomly allocated into four dietary treatments (H₀, H₁, H₂ and H₃ groups). A basal diet (H₀), basal diet plus 0.1 (H₁), 0.2 (H₂) and 0.3% (H₃) humate (Farmagulator DRY^?, Humate, Farmavet International Inc, Kocaeli 41 400, Turkey) were offered during the experimental feeding period. At the end of the trial all chicks were slaughtered. After standard dissection of carcasses, the breasts and drumsticks were divided into two groups for vacuum packaging or aerobic packaging. Packed breasts and drumsticks were stored at 3 °C for 12 days. The breasts and drumsticks were analyzed for pH, TBARS, total mesophilic, total psychrotrophic, lactic acid bacteria and Enterobacteriacea counts at 0, 2, 4, 6, 8, 10 and 12 days of storage. The feeding of humate decreased pH values of breast fillets and drumstick muscles (p < 0.01), especially at the 0.1% level. The TBARS value decreased (p < 0.01) when compared with the without‐humate group (H₀). Total aerobic mesophilic (p < 0.01), total aerobic psychrotrophic (p < 0.01) and lactic acid bacteria (p < 0.05) counts were lower in the H₃ group than the other groups. The effect of meat type on pH, TBARS, total aerobic mesophilic (p < 0.01) and lactic acid bacteria (p < 0.05) and Enterobacteriacea counts was significant. While the pH and TBARS values of breast fillets were lower than those of drumstick meats, the total mesophilic, total psychrotrophic, lactic acid bacteria and Enterobacteriacea counts of drumstick meats were higher than those of breast fillets. The effect of packaging type on pH (p < 0.01), TBARS (p < 0.01), total aerobic psychrotrophic bacteria (p < 0.01) and Enterobacteriacea counts (p < 0.01) was found statistically significant and the maximum values were determined in the aerobic‐packed samples. In addition, investigated parameters were also affected by storage period. While the total aerobic mesophilic count decreased, the other parameters increased when compared with zero day of storage. Copyright © 2005 Society of Chemical Industry     

Effect of storage temperatures and time on shelf‐life of sliced and modified atmosphere packaged Pastırma,a dried meat product,produced from beef

The effects of modified atmosphere on some physical, chemical and microbiological properties of sliced past?rma made from beef Longissimus dorsi muscle were investigated. Sliced‐past?rma samples (moisture 43.65 ± 0.15%, pH 5.71 ± 0.02) were stored in modified atmosphere packages (50% N₂ + 50% CO₂) at 4 and 10 °C for 150 days. The storage period had a significant effect (p < 0.01) on moisture, pH, thiobarbituric acid reactive substances, free fatty acid, non‐protein nitrogen, water‐soluble nitrogen, colour values and total aerobic bacteria, lactic acid bacteria and Micrococcus/Staphylococcus counts. The storage temperatures (4 and 10 °C) also had a significant effect (p < 0.01) on moisture, pH, thiobarbituric acid reactive subctances, free fatty acid, water soluble nitrogen, a* values, total aerobic bacteria lactic acid bacteria, and Micrococcus/Staphylococcus counts. It was determined that the storage period × the storage temperature interactions had a significant (p < 0.01) effect on the values of pH, a* and the counts of total aerobic bacteria, lactic acid bacteria, Micrococcus/Staphylococcus. It was also observed that the yeast and mold count was the highest in the first storage period and decreased throughout storage. Enterobacteriaceae count was also below the detectable level (<2.00 cfu g^?1) throughout the storage period. Copyright © 2005 Society of Chemical Industry