Effect of the degree of sulfation on the physicochemical and biological properties of Pleurotus eryngii polysaccharides

Polysaccharides extracted from Pleurotus eryngii were chemically modified by sulfation and the effects on the structural and biological properties of the polysaccharides were investigated as a function of the degree of sulfation. ¹³C NMR spectroscopy demonstrated that polysaccharides from P. eryngii were mainly composed of β-(1 → 3)-glucans with β-(1 → 6) branches. The structure of the sulfated polysaccharides was confirmed by FT-IR and their degree of substitution (DS) was determined to be 0.12–0.92. When P. eryngii polysaccharides were sulfated they were shown to be effective in inhibiting cancer cell growth in a dose-dependent way. Furthermore, their DPPH radical quenching effects were improved with increasing degree of sulfation. Thus, it seemed that the chemical modification of P. eryngii polysaccharides by sulfation effectively enhanced their potential biological properties.     

Antagonistic and antioxidant effect of probiotic Weissella cibaria JW15

Food Science and Biotechnology - The objective of this study was to evaluate the functional properties of Weissella cibaria JW15 (JW15) by investigating its antagonistic and antioxidant activities....     

Molecular thermodynamics of binary polymer solutions using modified double lattice model: Chain length dependence of primary lattice

In a previous study we modified a double lattice model by introducing a new interaction parameter, which improved the mathematical approximation defect, and gave a new expression for the Helmholtz energy of mixing. In the model the universal constants C_β and C_γ in the primary lattice were determined by comparing them with literature Monte Carlo simulation data, which is the only case for r₁ = 1 and r₂ = 100 (case I). In this study we introduce new universal constants, C_β and C_γ, as a function of the chain length of a polymer in a solvent (case II) by comparing them with other literature simulation data for various polymer chain lengths. The proposed model is compared with polymer–solvent systems. In an upper critical solution temperature phase behavior the theoretical results of case II were improved over those of case I. However, in a lower critical solution temperature phase behavior those of case I were not very sensitive to C_β and C_γ. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2627–2633, 1999     

Photocatalytic Water Splitting over La2Ti2O7 Synthesized by the Polymerizable Complex Method

Highly donor-doped (110) layered perovskite materials, La₂Ti₂O₇, with high surface areas were synthesized by the polymerizable complex (PC) method. Relative to La₂Ti₂O₇ prepared by the solid state reaction (SSR) method, PC catalysts showed higher surface areas, crystallization at lower temperatures, higher phase purity, more uniform morphology and better-distributed nickel on the outer surface of La₂Ti₂O₇. All these factors led to higher photocatalytic activity for overall water splitting under UV irradiation. The quantum yield of the reaction over La₂Ti₂O₇ prepared by the PC method was as high as 27%, which was about twofold greater than that over La₂Ti₂O₇ prepared by the SSR method.     

Protein Ligation-Assisted Reconstitution of Split HRP Fragments for Facile Production of HRP Fusion Proteins in E. coli

Horseradish peroxidase (HRP) is a pivotal biocatalyst for biosensor development and fine chemical synthesis. HRP proteins are mostly extracted and purified from the roots of horseradish because the solubility and productivity of recombinant HRP in bacteria are significantly low. In this study, we investigate the reconstitution system of split HRP fragments to improve its soluble expression levels in E. coli allowing the cost-effective production of bioactive HRPs. To promote the effective association between two HRP fragments (HRPn and HRPc), we exploit SpyTag-SpyCatcher chemistry, a versatile protein coupling method with high affinity and selectivity. Each HRP fragment was genetically fused with SpyTag and SpyCatcher, respectively, exhibiting soluble expression in the E. coli cytoplasm. The engineered split HRPs were effectively and irreversibly reconstituted into a biologically active and stable assembly that can catalyze intrinsic enzymatic reactions. Compared to the chaperone co-expression system, our approach shows that the production yield of soluble HRP is comparable, but the purity of the final product is relatively high. Therefore, our results can be applied to the high-yield production of recombinant HRP variants and other difficult-to-express proteins in bacteria without complex downstream processes.     

Optimization of LC droplet size and electro‐optical properties of acrylate‐based polymer‐dispersed liquid crystal by controlling photocure rate

We investigated the effects of the different content ratios of 2‐ethylhexylacrylate (2‐EHA) and 2‐ethylhexylmethacrylate (2‐EHMA) on the relationships among the photopolymerization rate, morphology of liquid crystals (LCs) droplets, and electro‐optical properties of trifunctional urethane acrylate‐based polymer‐dispersed liquid crystal (PDLC) systems. Photo‐differential scanning calorimetry (DSC) analysis and resistivity measurement revealed that increasing 2‐EHMA content gradually decreased the photocure rate of trifunctional urethane acrylate‐based PDLCs, which prolonged the phase separation between the LC molecules and the prepolymers. Morphological observations and electro‐optical measurements demonstrated that trifunctional urethane acrylate‐based PDLCs with the 2‐EHA:2‐EHMA ratios from 4:1 to 3:2 in weight percent formed the favorable microstructures of LC droplets being within the range of 1–5 µm to scatter light efficiently and showed the satisfactory off‐state opacity and on‐state transmittance and the relatively low‐driving voltage. The microstructures of LC droplets and electro‐optical properties of trifunctional urethane acrylate‐based PDLCs could be usefully optimized by controlling the photocure rate using the different 2‐EHA/2‐EHMA content ratios. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3098–3104, 2013     

Evaluation of a Silver Nanoparticle Generator Using a Small Ceramic Heater for Inactivation of S. epidermidis Bioaerosols

Silver has been known to show antibacterial activity. Recently, silver nanoparticles have been become widely used in diverse applications. In a previous work by the authors, a small nanoparticle generator that uses a ceramic heater with a local heating area was developed. The performance of the device was evaluated in terms of the silver nanoparticles it generated. In the present article, a feasibility study regarding the inactivation of bacteria bioaerosols by the developed small silver nanoparticle generator is conducted to assess its possible use for the active control of indoor bioaerosols. To simulate the inactivation of bacteria on a surface exposed to air, an antibacterial test system consisting of an airborne silver nanoparticle generator, a bacteria bioaerosol generator, and two airborne bacteria samplers with membrane filters was utilized. Spherical polydisperse silver nanoparticles with mode diameters in the range of 10 ～ 27 nm were generated. Their size distribution was changed according the applied voltage and the airflow rate. S. epidermidis gram-positive bacteria having mode diameter of approximately 800 nm were aerosolized using a single-jet Collison nebulizer in an effort to verify the antibacterial activity of the silver nanoparticles in an air environment. With variables of 100 V and 6 L/min, the viability of S. epidermidis bacteria exposed to silver nanoparticles was lower than 5% for an exposure time ranging from 1 ～ 9 min. The viability curve was well represented in terms of the total surface area of the exposed silver nanoparticles. From the results, it was concluded that the developed small airborne silver nanoparticle generator has considerable potential as an active antimicrobial device for use in indoor air applications.     

Development of an Aerosol Dynamics Model for Dry Deposition Process Using the Moment Method

An aerosol dynamics model for dry deposition process is developed based on the moment method. Since it is hard to fully apply the moment method to the widely used dry deposition velocity expressions based on the resistance theory, the dry deposition velocity expression by Raupach et al. (2001) Raupach, M. R., Briggs, P. R., Ahmad, N. and Edge, V. E. 2001. Endosulfan Tansport: II. Modeling airborne Dispersal and Deposition by Spray and Vapor. J. Environ. Qual., 30: 729–740. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] is used. Detailed deposition mechanisms such as Brownian diffusion, gravitational settling, and impaction are considered in the expression. To verify the validity of the derived dynamic equation, aerosol dynamics for the dry deposition process is estimated with the expressions of Raupach et al. (2001) Raupach, M. R., Briggs, P. R., Ahmad, N. and Edge, V. E. 2001. Endosulfan Tansport: II. Modeling airborne Dispersal and Deposition by Spray and Vapor. J. Environ. Qual., 30: 729–740. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar], of Wesely (1989) Wesely, M. L. 1989. Parameterizations of Surface Resistance to Gaseous Dry Deposition in Regional-Scale, Numerical Models. Atmos. Environ., 23: 1293–1304. [Crossref], [Web of Science ®] , [Google Scholar] modified for particles (Seinfeld and Pandis 1998 Seinfeld, J. H. and Pandis, S. N. 1998. Atmospheric Chemistry and Physics, 958–996. New York, , USA: Wiley.  [Google Scholar]), in CMAQ, and with constant value used in RAINS-ASIA. Those expressions give different dynamics. Generally, the result for this study is between the result of modified Wesely's expression and CMAQ. When using the modified Wesely's expression with the number of sections being equal or smaller than 10, the resultant size distribution does not give the peak shape accurately.     

使用校直辊工艺简易模拟方法的单层钢丝帘线质量评估

用作汽车轮胎增强材料的钢丝帘线是由盘条拉成细丝捻制而成。为满足轮胎的刚度需求,人们开发了不同类型的钢丝帘线。钢丝帘线的结构稳定性是其质量评估的重要因素之一。一般在钢丝帘线捻制工序后评估钢丝帘线的平直性和残余扭转。校直辊是利用周期弯曲变形来改善钢丝帘线的平直性和残余应力的一种装置。校直辊装置的工艺设计大多数情况下是基于工程师经验的反复试验,需要大量的时间和成本。因此需要一个有效工具来节省校直辊工艺设计的时间和成本。有限元分析模拟方法是校直辊工艺设计的一种有效选择。本工作提出通过有限元分析校直辊工艺数值模拟单层钢丝帘线质量的评估方法,以3×0.30单层钢丝帘线作为试验样品。简易模拟方法如     

The electrochemical behavior of an enzyme biosensor electrode using an oxyfluorinated pitch-based carbon

A glucose sensor electrode was prepared by thermally treating a pitch-based carbon material. Oxyfluorination was used to modify the surface of the prepared carbon to induce the formation of hydrophilic functional groups. A glucose oxidase enzyme was effectively loaded onto the surface of the oxyfluorinated carbon and was more sensitive in glucose sensing because of the effects of the improved interfacial affinity between the electrode and the glucose oxidase. The introduced hydrophilic functional groups were examined using XPS analysis. In current–voltage measurements, a higher current was observed in the samples prepared with a higher oxygen content. In addition, a clear redox peak was observed in the surface modified samples. These results can be attributed to efficient electrical resistance measurement by easy electron transfer during glucose sensing. An efficient glucose sensor electrode was prepared using pitch-based carbon, which has beneficial electrical properties, and oxyfluorination, which improves the surface interface.