Functional characterization of purified pear protease and its proteolytic activities with casein and myofibrillar proteins

This study was performed to characterize pear protease proteolytic activity and investigate the use of pear protease as a meat tenderizer. Pear protease was purified and stabilized by 5% dextrin during lyophilization (dry) or concentration (liquid). Pear protease was further characterized with respect to pH, thermodynamics, and enzyme kinetics. Pear protease was stable at a pH range of 5-8 with an optimum pH of 6.5. From Arrhenius plots, liquid protease showed higher temperature dependency (23.49 kJ/mol) than dry protease (18.62 kJ/mol) due to its higher activation energy. The kcat/Km, catalytic efficiency of enzyme, was similar with 2.9 and 2.7 µM/min with dry and liquid proteases. Pear protease was evaluated for its proteolytic activities with casein and beef myofibrillar proteins by individually and combination with fig and kiwifruit proteases. These result indicated that pear and kiwifruit proteases could be complementary to be a desirable product for meat tenderization.     

An effective digitized GPS signal transmission for high temporal precision IoT services

The Journal of Supercomputing - Owing to its potential applications such as military, industrial and civilian areas, most researchers and manufacturers pay attention to develop diverse smart...     

Characterization of sulfonated poly(styrene-co-pyrrolidone) pore-filling membranes for fuel cell applications

Pore-filling membranes using three monomers, i.e., styrene, N-vinyl pyrrolidone (VP), and divinylbenzene (DVB), are prepared for polymer electrolyte fuel cell (PEFC) applications. A porous polyethylene (PE) film substrate is used to enhance the dimensional stability of the prepared membranes. The proton conductivity and the water uptake of the styrene/VP/DVB membranes are similar to those of the styrene/DVB membranes, even though their ion exchange capacity is slightly lesser than that of the styrene/DVB membranes. Furthermore, the thermal stability of the styrene/VP/DVB membranes is higher than that of the styrene/DVB membranes, and, for the same DVB content, the membranes containing VP exhibit better oxidative stability. VP increases the membrane’s water-absorbing ability due to its intrinsic hydrophilic property and decreases weak α-hydrogen derived from the sulfonated styrene. Finally, the membrane-electrode assembly (MEA) using the 80/10/10 (Styrene/VP/DVB in weight percentage) membrane shows better performance than that using the 90/0/10 membrane.     

Preparation of organic/inorganic composite membranes using two types of polymer matrix via a sol–gel process

Organic/inorganic composite membranes were prepared using two different polymers. BPO₄ particles were introduced into polymers via an in situ sol–gel process. Pre-/post-sulfonated polymers were used to prepare composite membranes as matrix. Pre-sulfonated poly(aryl ether ketone) (SPAEK-6F) copolymer was synthesized via nucleophilic aromatic substitution. Degree of sulfonation was adjusted by the percentage of sulfonated monomer. Post-sulfonated poly(ether ether ketone) (SPEEK) was prepared using concentrated sulfuric acid as sulfonation agent. The membranes were characterized in terms of the ion-exchange capacity (IEC), proton conductivity, water uptake, AFM, SEM and their thermal properties. The SPAEK-6F plain membranes showed higher proton conductivity than that of the SPEEK plain membranes at similar water uptake or IEC due to their structural difference. SEM images of the composite membranes showed that the BPO₄ particles were homogenously dispersed in the polymer matrices and BPO₄ particle size was greatly influenced by polymer matrix. The SPAEK-6F/BPO₄ composite membranes had much smaller BPO₄ particle size than the SPEEK/BPO₄ composite membranes due to well dispersion of BPO₄ sol-like particulates in SPAEK-6F polymer solutions forming more hydrophobic/hydrophilic nanophase than SPEEK polymer solutions. The latter containing a few micrometer-scale BPO₄ particles showed higher proton conductivity than the former containing hundreds nanometer-scale BPO₄ particles at similar water uptake due to the increase in freezable water and effect of particle size.     

Effects of a blade profile, the Reynolds number, and the solidity on the performance of a straight bladed vertical axis wind turbine

This study investigates the effects of parameters such as a blade profile (changing the digit of the 4-digit NACA00xx airfoil), the Reynolds number, and the solidity on the performance characteristics of a straight bladed vertical axis wind turbine (VAWT). A numerical analysis, adopting the multiple stream tube (MST) method, is carried out to evaluate the performance depending on the parameters. The numerical result shows that the variation of a blade profile directly influences the power production, i.e., the high-digit NACA00xx airfoil provides higher power in a low speed zone (BSR < 3; BSR: blade speed ratio (ΩR/U _f ), Ω: angular velocity of blade, R: radius of a straight Darrieus wind turbine, U _f : free stream velocity) than the low-digit NACA00xx profile. On the contrary, the low-digit NACA00xx airfoil produces higher power in a high speed range (BSR > 5) than the high-digit NACA00xx profile. An enhancement of the power production is observed with increasing the Reynolds number on the whole tested blade speed ratio range (1 < BSR < 12). In particular, the rate of the enhancement of the power is rapidly decreased with the increases of the Reynolds number ( $Re = {{\rho \bar U_r c} \mathord{\left/ {\vphantom {{\rho \bar U_r c} \mu }} \right. \kern-0em} \mu }$ , ρ: air density, $\bar U_r$ : mean resultant velocity acting on a blade with variable rotating speeds in a uniform free stream velocity (U _f ), c: blade chord length, µ: air viscosity). For the effect of the solidity on the power production, a marked reduction of the range of the blade speed ratio that can provide the power is observed with increasing the solidity. A pattern of very steep variation of the power around the peak in the low speed zone (BSR < 3) is found in a high solidity range (σ > 0.3; σ: solidity (N _c /R), N: number of blade, c: chord length of an airfoil), and this tendency is conspicuously different from that of the eggbeater-type Darrieus VAWT, which is interpreted as a gradual variation of the power around the peak.     

Radiation damage in nano-crystalline tungsten: A molecular dynamics simulation

This study presents MD simulations for the radiation damage of single- and nano-(poly)crystalline tungsten. The nano-(poly)crystalline microstructure was constructed using a new construction method combined with the phase field model. At the maximum damage state, the recombination rate of self-interstitial atoms (SIAs) and vacancies is faster in the single-crystal that in the poly-crystal structure. In the steady state, the number of SIAs is twice as large in the nano-crystal, as caused by the attractive interaction between the grain boundary and the SIAs.     

A mesoporous composite template composed of self-assembled silica nanotube and multi-walled carbon nanotube

The multi-walled carbon nanotubes (MWNTs) were successfully embedded in the hexagonally-arranged silica tubular structure by the self-organization of two surfactant systems providing a MWNT-incorporated silica nancomposite template. The anionic surfactant (sodium dodecyl sulfate, SDS) adsorbed on the MWNT surfaces allowed the MWNTs to interact with the outer surface of the self-assembled non-ionic surfactant, poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) triblock copolymer. Due to the hydrophilic–hydrophilic interaction between the PEO blocks and the sulfate group of SDS, the MWNTs were most possibly surrounded by the outer wall of the SBA-15 hexagonal tubes aligning in the longitudinal and transverse directions to the silica tube direction. According to the interplanar distances, electron microscopy images, and N₂ adsorption–desorption isotherms, the synthesized SBA-15/MWNT system exhibited the structural integrity of silica-tube arrangement and structural characteristics of MWNTs in terms of BET surface area and micropore volume. This work made it clear that the developed SBA-15/MWNT template could be used to synthesize various MWNT-incorporated 2-D replicas.     

The nature and impact of changes in home learning environment on development of language and academic skills in preschool children.

In this study, we examined changes in the early home learning environment as children approached school entry and whether these changes predicted the development of children's language and academic skills. Findings from a national sample of the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (N = 1,018) revealed an overall improvement in the home learning environment from 36 to 54 months of children's age, with 30.6% of parents of preschoolers displaying significant improvement in the home environment (i.e., changes greater than 1 SD) and with only 0.6% showing a decrease. More important, the degree of change uniquely contributed to the children's language but not to their academic skills. Home changes were more likely to be observed from mothers with more education and work hours and with fewer symptoms of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A scan restoration method for robust polar scan matching in dynamic environments

This paper addresses the problem of scan matching which is highly indispensable for mobile robot systems based on range sensors. Recently, polar scan matching (PSM) has been used in solving the problem because it is accurate and fast enough to be performed in real time. However, the performance of PSM degenerates when the portion of scan data from dynamic objects is excessively large. This paper proposes a scan restoration method to overcome this problem and improve the performance of PSM in dynamic environments. The proposed method restores the scan data from dynamic objects to appropriate scan data from static objects. First, whole scan data is segmented and classified as static and dynamic objects. Next, curvature functions are extracted from the classified segments and smoothed by interpolating the segments indicating dynamic obstacles. PSM with the proposed method was tested and evaluated in various real dynamic environments, which reveals that the proposed method can improve the performance of PSM in dynamic environments.