• Advances in nano research
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• v.6 no.1
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• pp.81-92
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• 2018

Biosynthesis of nanoparticles has acquired particular attention due to its economic feasibility, low toxicity and simplicity of the process. Extracellular synthesis of nanoparticles by bacteria and fungi has been stated to be brought about by enzymes and other reducing agents that may be secreted in the culture medium. The present study was carried out to determine the underlying mechanisms of extracellular silver nanoparticle synthesis by Pseudomonas hibiscicola isolated from the effluent of an electroplating industry in Mumbai. Synthesized nanoparticles were characterized by spectroscopy and electron microscopic techniques. Protein profiling studies were done using Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (1D-SDS PAGE) and subjected to identification by Mass Spectrometry. Characterization studies revealed synthesis of 50 nm nanoparticles of well-defined morphology. Total protein content and SDS PAGE analysis revealed a reduction of total protein content in test (nanoparticles solution) samples when compared to controls (broth supernatant). 45.45% of the proteins involved in the process of nanoparticle synthesis were identified to be oxidoreductases and are thought to be involved in either reduction of metal ions or capping of synthesized nanoparticles.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2001.10a
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• pp.47.1-47
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• 2001

One of the problems associated with in vitro culture of primordial gern cells (PGCs) is the large loss of cells during the initial period of culture. This study characterized the initial loss and determined the effectiveness of two classes of apoptosis inhibitors, protease inhibitors and antioxidants, on the ability of the porcine PGCs to survive in culture. Results from electron microscopic analysis and in situ DNA fragmentation assay indicated that porcine PGCs rapidly undergo apoptosis when placed in culture. Additionally, \ulcorner2-macroglobulin, a protease inhibitor and cytokine carrier, and N-acetylcysteine, an antioxidant, increased the survival of PGCs in vitro. While other protease inhibitors tested did not affect survival of PGCs, all antioxidants tested improved survival of PGCs (p<0.05). Further results indicated that the beneficial effect of the antioxidants was critical only during the initial period of culture. Finally, it was determined that in short-term culture, in the absence of feeder layer, antioxidants could partially replace the effect(s) of growth factors and reduce apoptosis. Collectively, these results indicate that the addition of \ulcorner2-macroglobulin and antioxidatns can increase the number of PGCs in vitro by suppressing apoptosis.

• Molecules and Cells
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• v.23 no.1
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• pp.57-63
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• 2007

Leukotrienes (LTs) are produced by several biosynthetic enzymes including cytosolic phospholipase $A_2$ ($cPLA_2$), 5-lipoxygenase (5-LO), and 5-lipoxygenase activating protein (FLAP) in the perinuclear area. In the present study, we showed that pretreatment with methyl-${\beta}$-cyclodextrin (MβCD), a cholesterol-depleting agent, dramatically reduced the synthesis of LTs in response to A23187 in mast cells. A23187-induced LT synthesis was inhibited by pretreatment with M${\beta}$CD, and this effect was reversed when cholesterol was added. In an approach to identifying the $M{\beta}CD$-sensitive protein(s), we observed that FLAP co-localized with flotillin-1, a lipid raft marker protein, in the lipid raft-rich low-density region of sucrose gradients. In addition, electron microscopic analysis revealed that FLAP co-localized with flotillin-1. Together, these results suggest that FLAP is present in cholesterol-rich lipid raft-like domains and that its localization in these domains is critical for LT synthesis.

• International Journal of Concrete Structures and Materials
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• v.8 no.1
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• pp.15-26
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• 2014

In order to study the capacities of a new occurrence of Brazilian clay samples as partial replacements of cement, a bentonite sample was selected for utilization in the natural and modified forms for present study. The natural bentonite (BBT) was modified by anchorament of 3-aminopropyltrietoxisilane ($BBT_{APS}$) and 3,2-aminoethylaminopropyltrimetoxisilane (BBTAEAPS) in the surface of component minerals of bentonite sample. The original and organo-bentonite samples were characterized by elemental analysis, scanning electron microscopic and textural analyses. The values of micropore area were varying from $7.2m^2g^{-1}$ for the BBT to $12.3m^2g^{-1}$ for the $BBT_{AEAPS}$. The bentonite samples were characterized by the main variable proportion of bentonite in the natural and intercalated forms (2, 5, 10, 15, 20, 25, 30, and 35 % by weight of cement) in the replacement mode whiles the amount of cementations material. The workability, density of fresh concrete, and absorption of water decreased as the substitution of ordinary Portland cement by perceptual of natural and modified bentonite increased. The results reveal that workability decreased with decrease of the amount of natural bentonite in the concrete, same behavior is observed for bentonite functionalized, varying from 49 to 28 mm. The energetic influence of the interaction of calcium nitrate in the structure of blends was determined through the calorimetric titration procedure.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.474-481
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• 2009

A novel microorganism, designated as LG12, was isolated from soil based on its ability to use acrylic acid as the sole carbon source. An electron microscopic analysis of its morphological characteristics and phylogenetic classification by 16S rRNA homology showed that the LG12 strain belongs to Rhodococcus erythropolis. R. erythropolis LG12 was able to metabolize a high concentration of acrylic acid (up to 40 g/l). In addition, R. erythropolis LG12 exhibited the highest acrylic acid-degrading activity among the tested microorganisms, including R. rhodochrous, R. equi, R. rubber, Candida rugosa, and Bacillus cereus. The effect of the culture conditions of R. erythropo/is LG12 on the production of 3-hydroxypropionic acid (3HP) from acrylic acid was also examined. To enhance the production of 3HP, acrylic acid-assimilating activity was induced by adding 1 mM acrylic acid to the culture medium when the cell density reached an $OD_{600}$ of 5. Further cultivation of R. erythropo/is LG 12 with 40 g/l of acrylic acid resulted in the production of 17.5 g/l of 3HP with a molar conversion yield of 44% and productivity of 0.22 g/l/h at $30^{\circ}C$ after 72 h.

• Journal of Korean Neurosurgical Society
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• v.42 no.3
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• pp.205-210
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• 2007

Objective : Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels mediate the hyperpolarization-activated currents (Ih) that participate in regulating neuronal membrane potential and contribute critically to pacemaker activity, promoting synchronization of neuronal networks. However, distinct regional and cellular localization of HCN channels in the brain have not been precisely defined. Aim of this study was to verify the precise cellular location of HCN1 channels in rat cerebellum to better understand the physiological role these channels play in synaptic transmission between CNS neurons. Methods : HCN1 expression in rat brain was analyzed using immunohistochemistry and electron-microscopic observations. Postsynaptic density-95 (PSD-95), otherwise known as locating and clustering protein, was also examined to clarify its role in the subcellular location of HCN1 channels. In addition, to presume the binding of HCN1 channels with PSD-95, putative binding motifs in these channels were investigated using software-searching method. Results : HCN1 channels were locally distributed at the presynaptic terminal of basket cell and exactly corresponded with the location of PSD-95. Moreover, nine putative SH3 domain of PSD-95 binding motifs were discovered in HCN1 channels from motif analysis. Conclusion : Distinct localization of HCN1 channels in rat cerebellum is possible, especially when analyzed in conjunction with the SH3 domain of PSD-95. Considering that HCN1 channels contribute to spontaneous rhythmic action potentials, it is suggested that HCN1 channels located at the presynaptic terminal of neurons may play an important role in synaptic plasticity.

• Macromolecular Research
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• v.14 no.2
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• pp.132-139
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• 2006

The dispersion of organoclay in ethylene propylene diene terpolymer (EPDM) matrix was correlated with the rheological and swelling properties of nanocomposites. X-ray diffraction pattern (XRD) and transmission electron microscopic (TEM) analysis exhibited the disordered-intercalated structure of EPDM/organoclay nanocomposite. The extent of the disordered phase increased with increasing organoclay content up to a limiting value of 3 wt% after which equilibrium tended towards intercalation. The dispersion effect of organoclay in EPDM matrix was clarified by the physicochemical properties like rheological response and swelling thermodynamics in toluene. The increase in viscoelastic properties of EPDM nanocomposite with increasing organoclay content up to 3 wt%, followed by a subsequent decrease up to 4 wt%, was correlated in terms of the disordered and ordered states of the dispersed nano-clay sheets. Swelling measurements revealed that the change in entropy of the swelling increased with the increase in disorder level but decreased with the increase in intercalation level of organoclay in the disordered-intercalated nanocomposite. The increase in solvent uptake was comparable with the free volume in EPDM matrix upon inclusion of silicate particles, whereas the inhibition in solvent uptake for higher organoclay loading was described by bridging flocculation.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.09a
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• pp.57-71
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• 1995

A simple mathematical model for gacilitated mass transport with a fixed site carrier membrane was derived by assuming an instantaneous, microscopic concentration (activity) fluctuation, The concentration fluctuation, developed due to reversible chemical reaction between carrier and solute, could acuse the higher chemical potential gradient and the facilitated transport. For mathematical formulation, an analogy was employed between the mass transfer for the facilitated transport with fixed site carrier membrane and the electron transfer in a parallel resistor-capacitor (RC) circuit. For the single RC model, it was assumed that a single capacitor represented the total carrier and a solute could not inter-diffuse between matrix and carrier, allowing only two diffusional pathways, This assumption was relaxed by adopting a serial combination of the parallel RC circuit. Here, a solute diffuses in two elements (matrix or carrier) can exchange its pathway, exhibiting four diffusional pathways. The current models were examined against experimental data and the agreement was exceptional.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.41-54
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• 1987

The purposes of this study were to evaluate the color differences those can exist between different brands of porcelain with identical shade designation, and to find their causes. For these purposes the following experiments were executed: The color of each opaque and layered porcelain specimen was determined by spectral reflectance measurements with a spectrophotometer. The compositions of each opaque porcelain powder were analyzed by qualitative, and quantitative analysis. Microscopic structures of each opaque porcelain were observed by scanning electron microscope. The results were as follows: 1. Identical shade of different brands of porcelain produced significantly different colors. 2. Color differences among the three brands were found under different light sources. 3. Color differences among the three brands were mostly a result of differences in kinds and amounts of opacifying agents and fluxes and microstructure of porcelain systems. 4. When porcelain systems have similar compositions and firing cycles, they produced similar colors.

• Economic and Environmental Geology
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• v.16 no.3
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• pp.149-161
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• 1983

Fuller's earth deposits from Miocene sedimentary sequences in Gyeong Sang-do contain up to 95% Ca-montmorillonite accompanied by cristobalite, clinoptilolite, mordenite, quartz, feldspar and X-ray amorphous material. Differential thermal analysis, infrared and electron microscopic data are given for the montmorillonite component. The ease with which the exchangeable calcium of the montmorillonite could be replaced by sodium (to give a product with properties similar to that of a bentonite) was monitored by the Atterberg liquid limit test. Some samples tested as possible binders for foundry moulding sands gave results that compared favourably with material currently being used for this application. Many of the samples also met the OCMA specifications for clays used in drilling muds.