Purification and characterisation of an antioxidative peptide from enzymatic hydrolysates of duck processing by-products

Duck processing by-products were hydrolysed using eight proteases to produce an antioxidative peptide. Of the various hydrolysates produced, the pepsin extract exhibited the highest hydroxyl radical scavenging activity. The derived peptide was purified using high-performance liquid chromatography (HPLC) to identify any potent radical scavenging activity. The sequence of the antioxidative peptide obtained was identified as Asp-Val-Cys-Gly-Arg-Asp-Val-Asn-Gly-Tyr, with a molecular weight of 1096 Da. The IC₅₀ value of purified peptide for hydroxyl radical scavenging activity was 75 μg/ml as the measurement by an electron spin resonance (ESR) spectrometer. In addition, the purified peptide exhibited a protective effect on H₂O₂-induced DNA damage. These results indicate that the purified peptide possesses a potent antioxidative activity and protective effect of DNA against H₂O₂-induced oxidative damage.     

Optimization of citric acid production by <Emphasis Type="Italic">Aspergillus niger</Emphasis> NRRL 567 grown in a column bioreactor

Citric acid production using Aspergillus niger NRRL 567 grown on peat moss has been optimized in a column bioreactor using a statistically based method. A 23 full factorial design with eight fermentation conditions was applied to evaluate significance on citric acid production and their interactions between variables, where the three independent variables evaluated were aeration rate, bed depth and temperature. Aeration rate and fermentation temperature were identified to be significant variables. Citric acid production markedly increases with aeration rate and fermentation temperature; however, the bed depth of solid substrate showed an insignificant effect on citric acid production. The optimum fermentation condition for citric acid production in a column bioreactor consisted of aeration rate of 0.84 vvm, bed depth of 22 cm and fermentation temperature of 32 °C. Under a given condition, a maximum citric acid production of 120.6 g/l was predicted and matched well with the experimental value of 123.9 g/kg.     

i-TagRanker: an efficient tag ranking system for image sharing and retrieval using the semantic relationships between tags

Folksonomy, considered a core component for Web 2.0 user-participation architecture, is a classification system made by user’s tags on the web resources. Recently, various approaches for image retrieval exploiting folksonomy have been proposed to improve the result of image search. However, the characteristics of the tags such as semantic ambiguity and non-controlledness limit the effectiveness of tags on image retrieval. Especially, tags associated with images in a random order do not provide any information about the relevance between a tag and an image. In this paper, we propose a novel image tag ranking system called i-TagRanker which exploits the semantic relationships between tags for re-ordering the tags according to the relevance with an image. The proposed system consists of two phases: 1) tag propagation phase, 2) tag ranking phase. In tag propagation phase, we first collect the most relevant tags from similar images, and then propagate them to an untagged image. In tag ranking phase, tags are ranked according to their semantic relevance to the image. From the experimental results on a Flickr photo collection about over 30,000 images, we show the effectiveness of the proposed system.     

Effect of the deposition time on the electrocatalytic activity of Pt/C catalyst electrodes prepared by pulsed electrophoresis deposition method

Pt/C electrodes are prepared by pulsed electrophoresis deposition (PED) from a Pt colloidal solution as a plating bath. The PED is optimized by varying the duty cycle and deposition time in a galvanostatic mode. The catalytic activities of the Pt/C electrodes are evaluated using the cyclic voltammetry technique. The loading amount of the Pt catalyst is controlled by varying the deposition time. Also, a single cell test is carried out using the Pt/C electrodes prepared with the PED method as a cathode. In the concentration polarization region (i.e., at 0.4 V), the current density for the Pt/C 10 min electrode is 0.845 A cm⁻², which is higher than the rest of the Pt/C electrodes.     

Enhanced production of carboxymethylcellulase by Cellulophaga lytica LBH-14 in pilot-scale bioreactor under optimized conditions involved in dissolved oxygen

The optimal conditions for the production of carboxymethylcellulase (CMCase) by Cellulophaga lytica LBH-14 at flask scale has been previously reported. In this study, we optimized the parameters involved in dissolved oxygen in 7 and 100 L bioreactors for pilot-scaled production of CMCase by C. lytica LBH-14. The optimal conditions of agitation speed and aeration rate for cell growth in 7 L bioreactors were 395 rpm and 0.98 vvm, whereas those for production of CMCase were 357 rpm and 0.55 vvm. The optimal inner pressures for cell growth and production of CMCase by C. lytica LBH-14 in 100 L bioreactors were 0.00 and 0.06MPa, respectively. The production of CMCase under an optimized inner pressure was 1.38 times higher than that without an inner pressure. The maximal production of CMCase by C. lytica under optimized conditions at pilot scale using rice bran and ammonium chloride was 153.6 U/mL, which was 1.39 times higher than that at flask scale.     

Cucurbitacin B-, E-, and I-Induced Browning of White Adipocytes Is Promoted by the Inhibition of Phospholipase D2

The mechanism of white adipose tissue browning is not well understood; however, naturally occurring compounds are known to play a positive role. The effects of cucurbitacins B, E, and I on the browning of mature white adipocytes were investigated. First, the cell viability exhibited by cucurbitacins B, E, and I in pre- and mature adipocytes was verified. Cucurbitacins B, E, and I had no effect on cell viability in pre- and mature adipocytes at concentrations up to 300 nM. To investigate the characteristics of representative beige adipocytes, the formation and morphology of cucurbitacin B, E, and I lipid droplets were verified. The total lipid droplet surface area, maximum Feret diameter, and total Nile red staining intensity of cucurbitacin B-, E-, and I-treated adipocytes were lower than those of mature white adipocytes. Furthermore, treatment of white mature adipocytes with cucurbitacin B, E, and I led to the formation of several small lipid droplets that are readily available for energy expenditure. We evaluated the effect of cucurbitacins B, E, and I on the expression of representative browning markers UCP1, PGC1a, and PRDM16, which participate in the browning of white adipose tissue. Cucurbitacins B, E, and I increased the mRNA and protein expression levels of UCP1, PGC1a, and PRDM16 in a concentration-dependent manner. To promote energy consumption by beige adipocytes, active mitochondrial biogenesis is essential. Next, we investigated the effects of cucurbitacin B, E, and I on mitochondrial biogenesis in mature adipocytes. Mitochondrial mass increased when mature adipocytes were treated with cucurbitacin B, E, and I. The degree of cucurbitacin B-, E- and I-induced transformation of white adipocytes into beige adipocytes was in the order of Cu E > Cu B > Cu I. To verify the effect of phospholipase D2 on the browning of white adipocytes, CAY10594—a PLD2 pharmacological inhibitor, and a knockdown system were used. PLD2 inhibition and knockdown improved the expression levels of UCP1, PGC1a, and PRDM16. In addition, PLD2 inhibition and knockdown in mature white adipocytes promoted mitochondrial biosynthesis. The effect of PLD2 inhibition and knockdown on promoting browning of white adipocytes significantly increased when Cu B, Cu E, and Cu I were co-treated. These data indicate that mature white adipocytes’ beige properties were induced by cucurbitacins B, E, and I. These effects became more potent by the inhibition of PLD2. These findings provide a model for determining anti-obesity agents that induce browning and increase energy expenditure in mature white adipocytes.     

Energy efficient clustering algorithm for the mobility support in an IEEE 802.15.4 based wireless sensor network

The traditional clustering algorithm is an advanced routing protocol for enhancing an energy efficiency, which selects a cluster head and transmits the aggregated data arriving from the sensor nodes in the cluster to a gateway. However, the existing literature works were not suitable for an IEEE 802.15.4 beacon enabled mode and did not provide the combined solution for an energy efficient scheduling and handover of the sensor nodes. To address these problems, in this paper, we propose an energy efficient clustering algorithm for the mobility support in IEEE 802.15.4 networks. The simulation results show that the proposed scheme reduces the energy consumption and the packet loss, thus enhancing the performance.

     

Bacterial community analysis during fermentation of ten representative kinds of kimchi with barcoded pyrosequencing

Kimchi, a food made of fermented vegetables, is densely populated by indigenous microorganisms that originate from the raw ingredients under normal conditions. Most microbiological studies on kimchi have been on the most popular dish, baechu-kimchi (Chinese cabbage kimchi). Therefore, relatively little is known about the various other kinds of kimchi (depending on the region, season, main ingredient, starter culture inoculation and recipe). In this study, we collected 100 samples periodically during the fermentation of ten representative kinds of kimchi (including starter-inoculated kimchi) that were stored in the refrigerator (4 °C) during the 30−35 days fermentation period. The multiplex barcoded pyrosequencing of a hypervariable V1−V3 region of the 16S ribosomal RNA (rRNA) gene tagged with sample-specific barcodes for multiplex identifiers was employed for bacterial community profiling. We found that bacterial communities differed between starter-inoculated and non-inoculated kimchi at the early stages of fermentation, but overall there were no significant differences in the late phases. Also, the diversity and richness of bacterial communities varied depending on the various types of kimchi, and these differences could largely be explained by the major ingredients and the manufacture processes of each types of kimchi. This study provides the comprehensive understanding of the factors influencing the biodiversity of the kimchi ecosystem.     

Adsorption characteristics of HCA(Hydrocarbon Adsorber) catalysts for hydrocarbon and NOx, removals under cold-start engine conditions

To meet the SULEV (Super Ultra Low Emission Vehicle) regulations, we have focused on the utilization of HCA (Hydrocarbon Adsorber) in order to adsorb the excess hydrocarbons emitted during a period of engine cold-start. As main recipes of HCA materials, many types of zeolite as well as a combination of alumina and precious metals were used. Representative physico-chemical factors of zeolite such as acidic and hydrophobic properties have been characterized and tried to find the optimum recipe of HCA materials. Among the acid properties of zeolites, the Si/ Al ratio has been found to be the most important factor to achieve higher hydrocarbon adsorption capacity.     

Importance of Terminal Group Pairing of Polymer Donor and Small-Molecule Acceptor in Optimizing Blend Morphology and Voltage Loss of High-Performance Solar Cells

As a variety of non-fullerene small molecule acceptors (SMAs) have been developed to improve power conversion efficiency (PCE) of organic solar cells (OSCs), the pairing of the SMAs with optimal polymer donors (P_Ds) is an important issue. Herein, a systematic investigation is conducted with the development of the SMA series, named C6OB-H, C6OB-Me, and C6OB-F, which contain distinctive terminal substituents –H, –CH₃, and –F, respectively. These SMAs are paired with two P_Ds, PBDT-H and PBDT-F. Interestingly, the P_D/SMA pairs with similar terminal groups yield enhanced molecular compatibility and energetic interactions, which suppress voltage loss while improving blend morphology to enhance simultaneously the open–circuit voltage, short–circuit current, and fill factor of the OSCs. In particular, the OSC based on the PBDT-F:C6OB-F blend sharing fluorine terminal groups achieves the highest PCE of 15.2%, which outperforms those of PBDT-H:C6OB-F (10.1%) and PBDB-F:C6OB-H OSCs (11.2%). Furthermore, the PBDT-F:C6OB-F OSC maintains high PCEs with active layer thicknesses between 85 and 310 nm. In contrast, the PCE of PBDT-H:C6OB-F-based OSC already drops by 80% from 10.1% to 2.1% when the active layer thickness increases from 100 to 200 nm. This study establishes an important P_D/SMA pairing rule in terms of terminal functional groups for achieving high-performance OSC.