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ABSTRACT: Nanoparticles possess unique chemical and biological properties compared to bulk materials. Bioactive food components encapsulated in nanoparticles may have increased bioavailability and bioactivities.
Self-assembled nanoparticles made of partially purified pomegranate ellagitannins (PPE) and gelatin were fabricated using three PPE-to-gelatin mass ratios (1:5, 5:5, and 7:5). The PPE contained 16.6% (w/w) of punicalagin A, 32.5% (w/w) of punicalagin B, and a small amount of ellagic acid-hexoside and ellagic acid (1%, w/w). Nanoparticles fabricated using the ratio 5:5 had a particle size of 149.3±1.8 nm, positive zeta-potential of 17.8±0.9 mV, production efficiency 53.0±4.2%, and spherical morphology under scanning electron microscopy. Loading efficiency of punicalagin A and punicalagin B in these particles were 94.2±0.4% and 83.8±0.5 %, respectively. Loading capacity was 14.8±1.5% and 25.7±2.2%, respectively. Only punicalagin anomers were able to bind with gelatin to form nanoparticles, whereas ellagic acid-hexoside or ellagic acid could not. Fourier transform infrared spectroscopy suggested that the interactions between ellagitannins and gelatin were hydrogen bonding and hydrophobic interactions. PPE-gelatin nanoparticle suspension was less effective than PPE in inducing the early stage of apoptosis on human promyelocytic leukemia cells HL-60. But they had similar effects in inducing late stage of apoptosis and necrosis.
Pomegranate ellagitannins bind with gelatin to form self-assembled nanoparticles. Ellagitannins encapsulated in nanoparticles had decreased apoptotic effects on leukemia cells HL-60.
Molecular Nutrition & Food Research 03/2011; 55(7):1096-103. · 4.30 Impact Factor
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ABSTRACT: Nanoparticles were fabricated using self-assembly between partially purified ellagitannins (PPE) and gelatin. The factors affecting fabrication of nanoparticles, including PPE-to-gelatin mass ratio, pH, temperature, and reaction time, were investigated and the characteristics of formed nanoparticles, including sizes, zeta-potentials, and loading efficiency, were assessed. Nanoparticles that were fabricated using PPE-to-gelatin mass ratio from 1:5 to 6:5 had particle sizes from 121.5 to 129.0 nm. Increasing the ratio to 9:5 caused a drastic increase of particle size (620.7 nm) and was accompanied by formation of precipitation in the colloidal system. Nanoparticles fabricated in the pH range 4.0 to 5.3 (gelatin solution) had particle sizes ranging from 20.6 to 193.9 nm and zeta-potential between +14.7 and +23.8 mV, respectively. Loading efficiency of punicalagin A and B in the nanoparticles under these pH values ranged from 29.5% to 84.3% and from 10.6% to 73.9%, respectively. Extreme pH of gelatin solutions (pH 1.0, 2.0, 3.0, or 11.0) hindered the formation of nanoparticles due to possible hydrolyzation of ellagitannins and weakened affinity between ellagitannins and gelatin. Although gelatin at isoelectric point (pH 6-7) provided more hydrophobic sites to interact with ellagitannins, weakened zeta-potentials resulted in poor stability of nanoparticle suspension. Nanoparticles formed between 25 to 50 °C had particle size below 500 nm, whereas lower temperatures increased the size of nanoparticles. Nanoparticles were formed after 12 h of reaction time, and the nanoparticle colloidal suspension remained stable for 4 days. PPE-gelatin nanoparticles fabricated using PPE-to-gelatin mass ratio below 7:5, pH 4.0, temperature 25-40 °C, and reaction time 1.5 days had smaller particle sizes, higher zeta-potentials, and good loading efficiency.
Journal of Agricultural and Food Chemistry 03/2011; 59(8):4225-31. · 2.82 Impact Factor
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ABSTRACT: The group velocity dispersion (GVD) characteristics of a holey fibre design with a high index, slot structure in the core region are modified by introducing a simple cladding structure with a few large air holes. Our simulation results show that ultra-small mode effective areas and a high nonlinearity of the TE mode can be achieved, which is confined in the narrow slot by two silicon slabs in a glass fibre. This slot structure can be optimized to simultaneously achieve a very small Aeff and a single-TE-mode propagation. On the other hand, the proposed cladding can significantly reduce and flatten the large negative GVD of the slot structure, which could improve the nonlinear efficiency and interaction length for nonlinear applications. Our results indicate that an ultra-small Aeff of 0.16 µm2 and a flattened and reduced GVD with less than 10 ps nm − 1 km − 1 dispersion ripple within a 40 nm range at the 1.55 mm wavelength are achievable.
Journal of optics 09/2010; 12(11):115502. · 1.57 Impact Factor
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ABSTRACT: Antioxidants and phytochemicals in vegetables are known to provide health benefits. Strategies that enhance these properties are expected to increase the nutritional values of vegetables. The objective of this research is to assess the effects of exogenous abscisic acid (ABA) on yield, antioxidant capacities, and phytochemical content of lettuces grown in a greenhouse. Red loose leaf lettuce (cv. Galactic) and green loose leaf lettuce (cv. Simpson Elite) were cultivated using a randomized complete block design. Three concentrations of ABA in water [0 (control), 150, 300 ppm] were sprayed on the 30th and 39th days after sowing, and lettuces were harvested on the 46th day. Exogenous ABA significantly decreased yield of green and red lettuces. Total phenolic and total anthocyanin contents in red lettuce treated with ABA were significantly higher than in controls, whereas no significant differences were observed in green lettuce. ABA significantly induced the accumulation of chlorophyll b and total carotenoids in lettuces. The phenolic compounds identified and quantified in red and green lettuces included caffeoyltartaric acid, 5-O-caffeoylquinic acid, dicaffeoyltartaric acid, 3,5-dicaffeoylquinic acid, and quercetin 3-(6''-malonyl)-glucoside. Additionally, cyanidin 3-glucoside, cyanidin 3-(3''-malonoyl)-glucoside, and cyanidin 3-(6''-malonoyl)-glucoside in red lettuces were quantified. No significant effects of ABA on these individual phytochemicals were observed in green lettuces, whereas ABA significantly elevated the content of individual phytochemicals in red lettuces except for 5-O-caffeoylquinic acid. Differences among red lettuces with or without exogenous ABA were visualized on the score plots of principal component analyses. Loading plot indicated that multiple phenolic compounds contributed to the observed differences in red lettuces.
Journal of Agricultural and Food Chemistry 05/2010; 58(10):6503-9. · 2.82 Impact Factor
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ABSTRACT: A simple photonic crystal fiber (PCF) design with a rectangular array of four airholes in the core region and a traditional circular-airhole cladding is proposed in this work. The modal birefringence is induced by the asymmetry of the rectangular distribution of four airholes and/or the elliptical shape of the holes. The traditional symmetric cladding structure results in good confinement loss performance by limiting the light in the core region. Therefore, the proposed design enables simultaneous realization of high birefringence and low confinement loss. Simulations based on the full-vector finite element method (FEM) with anisotropic (PML) show that ultrahigh single-mode birefringence (~ 10<sup>-2</sup>) and ultralow confinement losses ( < 0.002 dB/km) can be achieved at 1.55 mum wavelength. Dependence study of the birefringence and losses on several key parameters is also provided. Compared to previously studied PCF with asymmetric core or cladding structures, by having just four relatively large airholes in the core, this design could be much easier to be implemented with even better performance.
Journal of Lightwave Technology 09/2009; · 2.78 Impact Factor
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ABSTRACT: A holey fiber design with a high index nanostructure that can achieve an effective mode area not in excess of 0.3 mum<sup>2</sup> and a flat dispersion at the 1.55 mum band is proposed and studied.
Lasers and Electro-Optics, 2009 and 2009 Conference on Quantum electronics and Laser Science Conference. CLEO/QELS 2009. Conference on; 07/2009
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ABSTRACT: We report a novel design of photonic crystal fiber (PCF) with a rectangular array of four closely-spaced, highly elliptical air holes in the core region and a circular-air-hole cladding. The proposed PCF is able to support ultra-wideband single-polarization single-mode (SPSM) transmission from the visible band to the near infrared band. With the aid of the inner cladding formed by the central air holes, one polarization of the fundamental mode can be cut off at very short wavelengths and ultra-wideband SPSM propagation can be achieved. The inner cladding also suppresses the higher order modes and allows large air filling fraction in the outer cladding while the proposed fiber remains SPSM, which significantly reduces the mode effective area and the confinement loss. Our simulation results indicate that the proposed PCF has a 1540 nm SMSP range with < 0.25 dB/km confinement loss and an effective area of 2.2 Pm 2 . Moreover, the group velocity dispersion (GVD) of the proposed PCF can also be tuned to be flat and near zero at the near infrared band (~800 nm) by optimizing the outer cladding structure, potentially enabling many nonlinear applications.
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ABSTRACT: a b s t r a c t We report a novel design of photonic crystal fiber (PCF) with a rectangular array of four closely-spaced, highly elliptical air holes in the core region and a circular-air-hole cladding. The proposed PCF is able to support ultra-wideband single-polarization single-mode (SPSM) transmission from the visible band to the near infrared band. With the aid of the inner cladding formed by the central air holes, one polarization of the fundamental mode can be cut off at very short wavelengths and ultra-wideband SPSM propagation can be achieved. The inner cladding also suppresses the higher order modes and allows large air filling fraction in the outer cladding while the proposed fiber remains SPSM, which significantly reduces the mode effective area and the confinement loss. Our simulation results indicate that the proposed PCF has a 1540 nm SMSP range with <0.25 dB/km confinement loss and an effective area of 2.2 lm 2 . More-over, the group velocity dispersion (GVD) of the proposed PCF can also be tuned to be flat and near zero at the near infrared band ($800 nm) by optimizing the outer cladding structure, potentially enabling many nonlinear applications.
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ABSTRACT: An all-optical regeneration scheme for DQPSK and QPSK signals using phase-sensitive amplifiers (PSAs) is studied and its effectiveness is investigated through numerical simulations. By leveraging the ability of PSAs to provide phase and amplitude regenerative amplification, we show significant simultaneous suppression of both phase and amplitude noises of (D)QPSK signals under optimized conditions. The reduction in the phase noise variance of a noise-corrupted DQPSK signal obtained by one such regenerative amplification can be as large as ∼5.5 folds, showing its good potential for distributed optical regeneration of (D)QPSK signals.
Optics Communications.
