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1.
2.
Properties and applications of β‐glycosidase from Bacteroides thetaiotaomicron that specifically hydrolyses isoflavone glycosides
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Da‐Hye Byun Hye‐Jeong Choi Hye‐Won Lee Hye‐Yeon Jeon Woo‐Jae Choung Jae‐Hoon Shim 《International Journal of Food Science & Technology》2015,50(6):1405-1412
To modify the glycan part of glycosides, the gene encoding β‐glycosidase was cloned from Bacteroides thetaiotaomicron VPI‐5482. The cloned gene, bt_1780, was expressed in Escherichia coli MC1061 and the expressed enzyme was purified using Ni‐NTA affinity chromatography. The purified enzyme, BTBG, showed optimal activity at 50 °C and pH 5.5. Interestingly, this enzyme did not have any hydrolysing activity on ordinary β‐linkage–containing substrates such as xylobiose, lactose and cello‐oligosaccharide, but specifically hydrolysed isoflavone glycosides such as daidzin, genistin and glycitin. Compared to a commercial beta glucosidase, BTBG selectively hydrolysed isoflavone glycosides in soybean extract mixture solution. These results suggest that BTBG may be a specialized enzyme for the hydrolysis of glycosides and that the substrate specificity of BTBG is applicable for the bioconversion of isoflavone glycosides in the food industry. 相似文献
3.
We have investigated the effect of extended dislocations (0.5-3 μm) on charge distribution in GaN epilayer grown by metalorganic chemical vapor deposition on (0001) sapphire using atomic force microscopy (AFM) and scanning surface potential microscopy (SSPM). It has been observed for the surface at the extended dislocations present in undoped GaN film to be negatively charged showing 0.04-0.2 V higher potential relative to regions that contain no dislocations. In addition to the higher potential at the dislocation core, the surrounding surfaces, including the edge of the dislocations, are also negatively charged in a symmetric way around the dislocations revealing crater-shaped higher potential regions (∼0.04 V) relative to surrounding dislocation-free area. The experimental results show that the protrusion-type of dislocation is also negatively charged and its potential is dependent on the size of dislocation. 相似文献
4.
In 2004, the American National Standards Institute approved the Role-Based Access Control standard to fulfill "a need among government and industry purchasers of information technology products for a consistent and uniform definition of role based access control (RBAC) features". Such uniform definitions give IT product vendors and customers a common and unambiguous terminology for RBAC features, which can lead to wider adoption of RBAC and increased productivity. However, the current ANSI RBAC Standard has several limitations, design flaws, and technical errors that, it unaddressed, could lead to confusions among IT product vendors and customers and to RBAC implementations with different semantics, thus defeating the standard's purpose. 相似文献
5.
Jinwook Kim Jeongsik Yang Sangjin Byun Hyunduk Jun Jeongkyu Park Conroy C.S.G. Beomsup Kim 《Solid-State Circuits, IEEE Journal of》2005,40(2):462-471
This work presents a quad-channel serial-link transceiver providing a maximum full duplex raw data rate of 12.5Gb/s for a single 10-Gbit eXtended Attachment Unit Interface (XAUI) in a standard 0.18-/spl mu/m CMOS technology. To achieve low bit-error rate (BER) and high-speed operation, a mixed-mode least-mean-square (LMS) adaptive equalizer and a low-jitter delay-immune clock data recovery (CDR) circuit are used. The transceiver achieves BER lower than <4.5/spl times/10/sup -15/ while its transmitted data and recovered clock have a low jitter of 46 and 64 ps in peak-to-peak, respectively. The chip consumes 178 mW per each channel at 3.125-Gb/s/ch full duplex (TX/RX simultaneous) data rate from 1.8-V power supply. 相似文献
6.
The purpose of this work is to study the effects of specularly reflecting wall under the combined radiative and laminar free
convective heat transfer in an infinite square duct. An absorbing and emitting gray medium is enclosed by the opaque and diffusely
emitting walls. The walls may reflect diffusely or specularly. Boussinesq approximation is used for the buoyancy term. The
radiative heat transfer is evaluated using the direct discrete ordinates method. The parameters under considerations are Rayleigh
number, conduction to radiation parameter, optical thickness, wall emissivity and reflection mode. The differences caused
by the reflection mode on the stream line, and temperature distribution and wall heat fluxes are studied. Some differences
are observed for the categories mentioned above if the order of the conduction to radiation parameter is less than order of
10-3 for the range of Rayleigh number studied. The differences at the side wall heat flux distributions are observed as long as
the medium is optically thin. As the top wall emissivity decreases, the differences between these two modes are increased.
As the optical thickness decreases at the fixed wall emissivity, the differences also increase. The difference of the streamlines
or the temperature contours is not as distinct as the side wall heat flux distributions. The specular reflection may alter
the fluid motion. 相似文献
7.
Myeongjoo Son Seyeon Oh Junwon Choi Ji Tae Jang Kuk Hui Son Kyunghee Byun 《International journal of molecular sciences》2021,22(8)
Hypertension induces renal fibrosis or tubular interstitial fibrosis, which eventually results in end-stage renal disease. Epithelial-to-mesenchymal transition (EMT) is one of the underlying mechanisms of renal fibrosis. Though previous studies showed that Ecklonia cava extracts (ECE) and dieckol (DK) had inhibitory action on angiotensin (Ang) I-converting enzyme, which converts Ang I to Ang II. It is known that Ang II is involved in renal fibrosis; however, it was not evaluated whether ECE or DK attenuated hypertensive nephropathy by decreasing EMT. In this study, the effect of ECE and DK on decreasing Ang II and its down signal pathway of angiotensin type 1 receptor (AT1R)/TGFβ/SMAD, which is related with the EMT and restoring renal function in spontaneously hypertensive rats (SHRs), was investigated. Either ECE or DK significantly decreased the serum level of Ang II in the SHRs. Moreover, the renal expression of AT1R/TGFβ/SMAD was decreased by the administration of either ECE or DK. The mesenchymal cell markers in the kidney of SHRs was significantly decreased by ECE or DK. The fibrotic tissue of the kidney of SHRs was also significantly decreased by ECE or DK. The ratio of urine albumin/creatinine of SHRs was significantly decreased by ECE or DK. Overall, the results of this study indicate that ECE and DK decreased the serum levels of Ang II and expression of AT1R/TGFβ/SMAD, and then decreased the EMT and renal fibrosis in SHRs. Furthermore, the decrease in EMT and renal fibrosis could lead to the restoration of renal function. It seems that ECE or DK could be beneficial for decreasing hypertensive nephropathy by decreasing EMT and renal fibrosis. 相似文献
8.
Jinhong Kim Junho Jang Sehui Yun Hyeon Deok Kim You Young Byun Yong Tae Park Jung Il Song Chungyeon Cho 《大分子材料与工程》2021,306(9):2100233
In an effort to develop highly functionalized flame retardant materials, hybrid nanocoatings are prepared by alternately depositing a positively charged polyaniline (PANi) and negatively charged montmorillonite (MMT) using the layer-by-layer (LbL) assembly technique. Carbon nanotubes (CNTs) are employed in polymer nanocomposites as effective reinforcement, where nanotubes are stabilized in MMT aqueous solution. The 3D structure and high density of CNTs deposited in the PANi/CNTs-MMT multilayers produce thicker and heavier coatings in comparison to the LbL assemblies without CNTs. Vertical and horizontal flame testing show that the incorporation of CNTs improves fire resistance. Additionally, cone calorimetry reveals that stacking two nanomaterials (MMT and CNTs) in a single coating shows a significant reduction in peak heat release rate (up to 51%), total smoke release (up to 47%), and total heat release (up to 37%) for the polyurethane foam. The enhancement of flame retardancy is attributed to a synergistic effect; MMT serves as a physical barrier that retards the diffusion of heat and gas. The addition of CNTs strengthens the thermal stability and high char yield. These results, coupled with the simplicity with which the LbL deposition is applied, present a viable alternative to halogen-free flame retardant nanocoatings to natural and synthetic fibers. 相似文献
9.
Chul Kwak Stanley I. Sandler Hun-Soo Byun 《Korean Journal of Chemical Engineering》2006,23(6):1016-1022
The correlation of vapor-liquid equilibrium data for high-pressure carbon dioxide systems is of interest in a number of industrial
applications, including supercritical extraction. Here, we consider the correlation of data for 12 binary systems of carbon
dioxide separately with alcohols, with hydrocarbons, and with acetone, benzene, and water. The Wong-Sandler (W-S) and modified
Huron — Vidal first order (MHV1) free energy-based equation of state mixing rules (the W-S and MHV1 models) were used in the
calculations. Both combined equation of state+free energy models generally resulted in good correlations of the experimental
data over wide ranges of temperature and pressure with temperature — independent parameters. However, for the carbon dioxide+water
system, the W-S model produced an 11% average absolute deviation in pressure, while no parameter that resulted in an AAD in
pressure of less than 20% could be found for the MHV1 model. 相似文献
10.
Experimental cloud-point data to temperature of 186 °C and pressure of ~2,500 bar are presented for ternary mixtures of poly(propyl
acrylate)(PPA)-CO2-propyl acrylate (PA) PPA-C2H4-PA and poly(propyl methacrylate) (PPMA)-CO2-propyl methacrylate (PMA) systems. Cloud-point pressures of PPA-CO2-PA system were measured in the temperature range of 32 °C to 175 dgC and to pressures as high as 2,070 bar with PA concentrations
of 0.0, 5.0, 11.7 and 30.4 wt%. Adding 34.1 wt% PA to the PPA-CO2 mixture significantly changes the phase behavior. This system changes the pressure-temperature slope of the phase behavior
curves from U-LCST region to LCST region as the PA concentration increases. Cloud-point data to 170 °C and 1,400 bar are presented
for PPA-C2H4-PA mixtures and with PA concentration of 0.0, 5.7, 15.5 and 22.2 wt%. The cloud-point curve of PPA-C2H4 system shows relatively flat at 730 bar for temperatures between 41 and 150 °C. With 15.5 and 22.2 wt% PA the cloud-point
curve exhibits a positive slope that extends to 35 °C and ~180 bar. Also, the ternary PPMA-CO2-PMA system was measured below
186 °C and 2,484 bar, and with cosolvent of 5.2-20.1 wt%. PPMA does not dissolve in pure CO2 to 233 °C and 2,500 bar. Also, when 41.5 wt% PMA is added to the PPMA-CO2 solution, the cloud-point curve shows the typical appearance of a lower critical solution temperature (LCST) boundary. 相似文献