• Microbiology and Biotechnology Letters
• /
• v.8 no.3
• /
• pp.193-198
• /
• 1980

Substantial numbers of malo-lactic bacteria were detected in Korean winery environment such as in grape juices, fermenting musts, lees, aging wines, and bottled apple wines. Among 1363 malo-lactic strains isolated from the above habitats, four superior strains were selected and identified as Leuconostoc oenos strain A-25, B-30, C-13 and Lactobacillus plantarum strain D-11. The strain A-25 showed malate utilizing activity almost equivalent to Leu. oenos ML34, a well-known malo-lactic bacterium. Upon experimental vinifications the malo-lactic fermentation efficiency of A-25 was confirmed.

• Steel and Composite Structures
• /
• v.44 no.6
• /
• pp.817-828
• /
• 2022

In this study, considering dissipated energy in fracture process zone (FPZ), a novel criterion based on maximum strain energy release rate (SER) for orthotropic materials is presented. General case of in-plane loading for cracks along the fibers is assumed. According to the experimental observations, crack propagation is supposed along the fibers and the reinforcement isotropic solid (RIS) concept is employed as a superior model for orthotropic materials. SER in crack initiation and propagation phases is investigated. Elastic properties of FPZ are extracted as a function of undamaged matrix media and micro-crack density. This criterion meaningfully links between dissipated energy due to toughening mechanisms of FPZ and the macroscopic fracture by defining stress intensity factors of the damaged zone. These coefficients are used in equations of maximum SER criterion. The effect of crack initiation angle and the damaged zone is considered simultaneously in this criterion and mode II stress intensity factor is extracted in terms of stress intensity factors of damage zone and crack initiation angle. This criterion can evaluate the effects of FPZ on the fracture behavior of orthotropic material. Good agreement between extracted fracture limit curves (FLC's) and available experimental data proves the ability of the new proposed criterion.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.7
• /
• pp.1093-1100
• /
• 2015

Acetate and lactate in growth media are detrimental to the production of Thermus maltogenic amylase (ThMA), a heterologous protein, as well as to the growth of recombinant Escherichia coli. Only 50 mM of acetate or 10 mM of lactate reduced 90% of specific ThMA activity. In this study, mutant E. coli strains blocked in the ackA-pta or ackA-pta and ldh pathways were created, characterized, and assessed for their culture performace in 300 L-scale fermentation. The ackApta and ldh double-mutant strain formed significantly less lactate and acetate, and produced a concomitant increase in the excretion of pyruvate (17.8 mM) under anaerobic conditions. The ackA-pta mutant strain accumulated significant acetate but had an approximately 2-fold increase in the formation of lactate. The ackA-pta and ldh double-mutant strain had superior overall performance in large-scale culture under suboptimal conditions, giving 67% higher cell density and 66% higher ThMA activity compared with those of the control strain. The doublemutant strain also achieved a 179% improvement in volumetric ThMA production.

• Journal of Korean Association for Spatial Structures
• /
• v.9 no.2
• /
• pp.77-82
• /
• 2009

ETFE is the abbreviation of Ethlene Tetra Fluoro Ethlene, a sort of colorless and transparent granules. The advantage of ETFE film has chemical resistance, anti-stick property, very lightly material. The thickness of ETFE film is used to from 50 ${\mu}m$ to 300 ${\mu}m$ and have superior ability of daylight transmission and elongation, while the strength is lower than of fabric membrane. The tensile strength of ETFE film changes from 40Mpa to 60Mpa and the tensile strain at break can get to about 300-400%. The mechanical characteristic test of ETFE film is described in this paper. The tensile strain at break, the tensile strength and the stress-strain curve are obtained from the test. And then it was analyzed stress-strain characteristic by temperature and mechanical characteristic by cycling load.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.1
• /
• pp.121-127
• /
• 2007

Muscle force produced by muscle fibers is transmitted to bones via tendinous structures(aponeuroses and tendon), resulting in joint(s) movement. As force-transmitting elements, mechanical behavior of aponeuroses and tendon are closely related with the function of muscle-tendon complex. The purpose of this study was to determine strain characteristics of aponeuroses for in-vivo human soleus muscle during submaximal voluntary contractions using an advanced medical imaging technique, velocity-encoded phase-contrast magnetic resonance imaging (VE-PC MRI). VE-PC MRI of the soleus muscle-tendon complex was acquired during submaximal isometric plantarflexion contraction-relaxation cycle (n = 7), using 3.0T Trio MRI scanner(Siemens AG, Malvern, MA). From the VE-PC MRI containing the tissue velocity in superior-inferior direction, twenty regions of interest(20 ROI; 10 on the anterior aponeurosis and 10 on the posterior aponeurosis) were tracked. During the isometric plantarflexion contraction-relaxation cycle, velocity and displacement profiles were different between the anterior and posterior aponeuroses, indicating heterogeneous strain behavior along the length of the leg. The anterior aponeurosis elongated while the posterior aponeurosis shortened during the initial phase of the contraction. Moreover, strain behavior of the posterior aponeurosis was different from that of the Achilles tendon. Possible explanation for the observed variations in strain behavior of aponeuroses was investigated with morphological assessment of the soleus muscle and it was found that the intramuscular tendinous structures significantly vary among subjects. In conclusion, the heterogeneous mechanical behavior of the soleus aponeuroses and the Achilles tendon suggests that the complexity of skeletal muscle-tendon complex should be taken into consideration when modeling the complex for better understanding of its functions.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.8 no.3
• /
• pp.173-178
• /
• 2003

To improve the erythritol productivity of Penicillium sp. KJ81, mutants were obtained using UV irradiation and NTG treatment Among these mutants, Penicillium sp. KJ-UV29 revealed no morphological changes, yet was superior to the wild strain in the following three points: (1) Penicillium sp. KJ-UV29 produced more erythritol than the wild strain under the same conditions, (2) no foam was produced during cultivation, unlike the wild strain, and (3) the mutant produced a Significantly lower amount of glycerol. Penirillium sp. KJ-UV29 produced as much as 15.1 g/L of erythritol, whereas the wild-type Penirillium sp. KJ81 only produced 11.7 g/L. Penicillium sp. KJ-UV29 only generated 6.1 g/L of glycerol, compared to 19.4 g/L produced by the wild strain. When investigating the optimal culture conditions for erythritol production by the mutant strain Penicillium sp. KJ-UV89, sucrose was identified as the most effective carbon source, and the mutant was even able to produce erythritol in a 70% sucrose-containing medium, although a 30% sucrose medium exhibited the highest productivity. The production of erythritol by Penirillium sp. KJ-UV29 was also significantly increased by the addition of ammonium carbonate, potassium nitrate, and sodium nitrate. Accordingly, under optimal conditions, Penicillium sp. KJ-UV29 produced 45.2 g/L of erythritol in a medium containing 30% sucrose, 0.5% yeast extract, 0.5% (NH$_4$)$_2$C$_2$O$_4$, 0.1% KNO$_3$, 0.1% NaNO$_3$, and 0.01% FeSO$_4$ with 1 vvm aeration and 200 rpm agitation at 37$^{\circ}C$ for 7 days in a 5-L jar fermentor.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.5
• /
• pp.232-236
• /
• 2010

Silicon carbide (SiC) ceramics are widely used in the application of high-temperature structural devices due to their light weight as well as superior hardness, fracture toughness, and temperature stability. In this paper, we employed classical molecular dynamics simulations using Tersoff's potential to investigate the elastic constants of the SiC crystal at high temperature. The stress-strain characteristics of the SiC crystal were calculated with the LAMMPS software and the elastic constants of the SiC crystal were analyzed. Based on the stress-strain analysis, the SiC crystal has shown the elastic deformation characteristics at the low temperature region. But the slight plastic deformation behavior was shown as applied the high strain over $1,000^{\circ}C$. Also the elastic constants of the SiC crystal were changed from about 475 GPa to 425 GPa as increased the temperature to $1,250^{\circ}C$.

• Journal of the Korea Convergence Society
• /
• v.12 no.11
• /
• pp.403-410
• /
• 2021

This paper aimed to increase the functionality and competitiveness of rice bran, which is used as an alternative food and cosmetic raw material, through fermentation. As a result of comparing the enzyme activity of 𝛼-amylase, CMCase, 𝛽-glucosidase, protease, etc. of fermented rice bran using standard strains with 6 strains with excellent enzyme activity among 50 strains of Saccharomycopsis fibuligera isolated from 5 types of Nuruk, A8 strain showed excellent enzyme activity of 13.7%, 21.1%, 50.3%, and 10.0% compared to the KCTC 7806 strain. As a result of the ABTS and DPPH tests as a result of fermentation, it was confirmed that rice bran fermented with A8 had 1.12 times and 1.28 times more antioxidant activity than rice bran fermented with KCTC 7806 strain. In this paper, it was possible to confirm the S. fibuligera A8 strain superior to the standard S. fibuligera strain KCTC 7806.

• Journal of Microbiology
• /
• v.42 no.3
• /
• pp.169-173
• /
• 2004

Enterobacter cloacae (strain PR2/7), a genetically modified endophyte(GME) in citrus plants, carrying different plasmids (pEC3.0/18, pCelE, pEglA and pGFP), was inoculated into Citrus sinensis seedlings under greenhouse conditions. The impact of this on the indigenous bacterial endophytic community was studied by analyses of 2 different morphologic groups. The germination rates of inoculated seeds were evaluated in greenhouse, and plasmid stability under in vitro conditions. Results demonstrated a great and diverse endophytic community inside plants, and specialization in tissue colonization by some bacterial groups, in different treatments. Shifts in seed germination rate were observed among treatments: in general, the PR2/7 harboring pEglA bacterial- clone significantly reduced seed germination, compared to the PR2/7 harboring pEC3.0/18 clone. This suggests that the presence of the pEglA plasmid changes bacteria-seed interactions. The endophytic community of citrus seedlings changed according to treatment. In seedlings treated with the PR2/7 with pEglA clone, the population of group II decreased significantly, within the context of the total endophytic community. These results indicate that the application of GMEs induces shifts in the endophytic bacterial community of citrus seedlings.

• The Korean Journal of Mycology
• /
• v.36 no.1
• /
• pp.51-57
• /
• 2008

To develop artificial cultivation and improve some problems such as auto-lysis on commercialization of Coprinus comatus that has been known edible and medicinal mushroom, they were conducted for selection of superior strain, suitable culture methods for mycelial growth and fruiting, and morphological characteristics of fruit body. Strain CM 980301 of Coprinus comatus was selected as a superior strain for artificial cultivation. Wheat grain and rice straw full-grown compost media were most effective for preparation of spawn and artificial cultivation of C. comatus, respectively. Spawn running of Coprinus spp. on the rice straw full-grown compost media required to be 15 days from 24 to $28^{\circ}C$. The casing layer incubation before initiation of fruit body formation, required for 13 days at same temperature for spawn running. And then require $10{\sim}11$ days for initiation and $7{\sim}8$ days for development of fruit body from 20 to $24^{\circ}C$. The fruit body of strain CM 980301 was harvested within a week from initiation of primordium formation. The hardness of pileus and stipe that were harvested in optimal stage showed 102 to 169, and 128 to $182\;g/cm^2$, respectively. Yields of srain CM 980301 from the rice straw full-grown compost media was $37.7kg/3.3m^2$. Weight of individual fruit body was 17.9 g in average.