• Journal of Microbiology and Biotechnology
• /
• 제30권6호
• /
• pp.920-925
• /
• 2020

In India, nanotechnology has been used in therapeutic applications for several millennia. One example of a traditional nanomedicine is Rajath Bhasma (also called calcined silver ash), which is used as an antimicrobial and for the treatment of various ailments and conditions such as memory loss, eye diseases, and dehydration. In this study, we aimed to characterize the physical composition and morphology of Rajath Bhasma and its suitability for use as a non-toxic antimicrobial agent. First, Rajath Bhasma was physically characterized via i) Fourier-transform infrared spectroscopy to analyze the surface functional groups, ii) scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy to observe the morphology and elemental composition, and iii) X-ray diffraction to determine the crystalline phases. Thereafter, functional characterization was performed through toxicity screening using zebrafish embryos and through antimicrobial activity assessment against gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria. Rajath Bhasma was found to harbor alkene, hydroxyl, aldehyde, and amide functional groups originating from biological components on its surface. The main component of Rajath Bhasma is silver, with particle size of 170-210 nm, and existing in the form of spherical aggregates with pure crystalline silver structures. Furthermore, Rajath Bhasma did not exert toxic effects on zebrafish embryos at concentrations below 5 ㎍/ml and exhibited effective antimicrobial activity against both gram-positive and gram-negative bacteria. The present results indicate that Rajath Bhasma is a potentially effective antimicrobial agent without toxicity when used at concentrations below 5 ㎍/ml.

• 한국토양비료학회지
• /
• 제48권4호
• /
• pp.285-294
• /
• 2015

Ordination has been recognized useful method to analyze the effects of multiple environmental factors on dozens of species in vegetation ecology because of summarizing community data by producing a low-dimensional graphics. Main objective of this study was the application of ordination method, especially principal components analysis (PCA), to analyze the soil characterization on paddy treated by different green manure crops and tillage methods. Treatments included the three tillage treatments and two green manure crops as the following; (i) moldrotary + rotary tillage without green manure crop (Con), with (ii) hairy vetch (ConHv), and (iii) hairy vetch + green barely (ConHvGb), (iv) rotary tillage without green manure crop (Rot), with (v) hairy vetch (RotHv), and (vi) hairy vetch + green barly (RotHvGb), and (vii) no-tillage (Notill). Vectorial distance result from PCA of soil properties including physical, chemical, and microbial properties showed the two main difference. Firstly, soil properties among plots without green manure were strongly affected by tillage strength [Vectorial distance: Con-Notil (5.88) > Rot-Notill (4.58)] at PC1 (35.0%) axis. But it was difficult to find the fixed trend among plots when green manure crop was added in plot. Nevertheless, two groups were separated by adding green manure crop at PC2 (29.2%) axis. These results show that PCA ordination methods could be used the research for change of soil characterization.

• 대한수의학회지
• /
• 제49권1호
• /
• pp.45-57
• /
• 2009

The molecular genetic characterization of Aujeszky's disease virus (ADV) Yangsan strain (ADVYS), a Korean isolate, was investigated by analyzing the electrophoresis patterns and the physical maps of the viral DNA digested with various endonucleases. To establish DNA library for ADV-YS, twelve major BamHI restricted segments were cloned. Each location of the segments in the ADV genome was determined by sequence comparison with the sequences reported in Genbank and those sequences of the both termini of the segments. Physical maps were constructed based on the electrophoresis patterns of the digested viral DNA by restriction endonuclease and the results of Southern blot analyses with various DIG labeled probes originated from those of enzyme restricted segments of virulent (Shope) and avirulent (Bartha) strain. Comparing ADV-YS with a standard strain of Kaplan in the maps of restriction enzymes, following major respects were identified: (i) disappearance of BamHI restriction site between the first and second BamHI segments, (ii) creation of the BamHI restriction site in the fifth segment, and (iii) generation of the BglII site in the unique short (US) region. The genome of ADV-YS also contains a type 2 herpesvirus DNA molecule (in which the US region only inverts itself relative to the unique longregion) like all other ADV strains except Norden strain(type3), analyzed up to date. The size of the ADV genome estimated from the sizes of the restriction enzyme fragments, was approximately 145.3 kb (BamHI) or 145.4 kb (BglII). BamHI enzyme cleavage patterns were compared among the five Korean ADV isolates: Yangsan, Yongin, Dangjin, Jincheon and Iksan strains. Difference either in the number or in the size of the DNA fragments, suspected regions of termini of IR and TR, could be detected among all five strains.

• 대한인간공학회지
• /
• 제30권2호
• /
• pp.331-338
• /
• 2011

Objective: The present study developed a comprehensive usability testing and analysis framework based on a physical interface model of product and user and applied the proposed framework to usability testing of canister-type vacuum cleaner. Background: The development of a user-centered product design is important to satisfy customers who want to use the product with ease of use and to keep the manufacturer competitive in the market. Method: The proposed testing and analysis framework consists of (1) characterization of physical product-user interface, (2) preparation and administration of usability testing questionnaire, and (3) analysis and interpretation of usability testing results. A usability evaluation of five vacuum cleaners was planned and administered based on the proposed framework and its analysis produced detailed and overall usability testing results for various aspects such as tasks, usability criteria, and design components. Results: The testing results were further utilized to identify usability problems and preferred design features of the vacuum cleaners. Conclusion: The proposed usability testing and analysis framework was found effective to identify preferred features and problems of a product design in a systematic, holistic manner. Application: The proposed framework can be of effective use for practitioners of product design and development to obtain comprehensive, quantitative usability testing information in a systematic manner.

• Korean Chemical Engineering Research
• /
• 제46권1호
• /
• pp.23-36
• /
• 2008

고분자-점토 나노복합체는 소량의 점토를 사용하여 큰 기계적 물성향상을 나타내 많은 관심을 끌고 있는 분야이다. 층상 구조를 갖고 있는 점토를 고분자 matrix에 분산하는 과정으로 요약할 수 있는 고분자-점토 나노복합체 제조는 친수성 점토 표면을 조절하는 기술, 점토의 물리적 성질을 이용하는 무기재료에 관한 지식, 고분자 합성, 고분자 유변학, 고분자 용액 거동, 기계적 물성이 복합적으로 작용하는 계이다. 이러한 복잡성을 설명하기 위해, 이 총설에서 점토 종류와 그 특성을 설명하였다. 또한 점토 특성과 고분자-점토 나노복합체 제조 방법의 연관성에 대해 설명하고, 제조된 복합체의 구조 분석과 방법에 대해 설명하였다. 그리고 복합체의 특징적인 물성을 분류한 후 그 물성과 복합체의 구조를 연관하여 살펴보았다. 마지막으로 최근의 연구 경향과 향후 연구 경향을 제시하였다.

• 한국염색가공학회지
• /
• 제34권2호
• /
• pp.117-126
• /
• 2022

In this study, thermoplastic composites were manufactured using ABS(acrylonitrile butadiene styrene), PC(polycarbonate), and POE(polyolefin elastomer), which are thermoplastic plastics. Twin screw extruder and injection molding were used to manufacture thermoplastic composites. When the ABS/PC/POE thermoplastic composite material was manufactured, the POE mass fraction was set to 1 to 5 wt.%, and the thermal and mechanical properties according to the POE mass fraction were analyzed. Based on the physical properties of ABS/PC/POE, a 3D model in the form of an e-bike frame was created. After setting the boundary conditions, when an external load is applied, geometry simulation was performed to predict product performance. The ABS/PC/POE thermoplastic composite material exhibited the best physical properties when the mass fraction of POE was 3 wt.%. In the simulation results for the physical properties of the 3D model in the form of an e-bike frame, the best physical properties were shown when the mass fraction of POE was 2 ~ 3 wt.%. As a result, the manufacturing conditions for ABS/PC/POE thermoplastic composite materials were set, and research was conducted to reduce product development costs and development time.

• Geomechanics and Engineering
• /
• 제34권4호
• /
• pp.449-459
• /
• 2023

The design and development of underground nuclear waste repositories should cover the performance evaluation of the different components such as the construction materials because the long term stability will depend on their response to the surrounding conditions. In South Korea, Gyeonju bentonite has been proposed as a candidate to be used as buffer and backfilling material, especially in the form of blocks to speed up the construction process. In this study, various cylindrical samples were prepared with different dry density and water content, and their physical and mechanical properties were analyzed and correlated with X-ray CT observations. The main objective was to characterize the samples and establish correlations for non-destructive estimation of physical and mechanical properties through the utilization of X-ray CT images. The results showed that the Uniaxial Compression Strength and the P-wave velocity have an increasing relationship with the dry density. Also, a higher water content increased the values of the measure parameters, especially for the P-wave velocity. The X-ray CT analysis indicated a clear relation between the mean CT value and the dry density, Uniaxial Compression Strength, and P-wave velocity. The effect of the higher water content was also captured by the mean CT value. Also, the relationship between the mean CT value and the dry density was used to plot CT dry densities using CT images only. Moreover, the histograms also provided information about the samples heterogeneity through the histograms' full width at half maximum values. Finally, the particle size and heterogeneity were also analyzed using the Madogram function. This function identified small particles in uniform samples and large particles in some samples as a result of poor mixing during preparation. Also, the μ_max value correlated with the heterogeneity, and higher values represented samples with larger ranges of CT values or particle densities. These image-based tools have been shown to be useful on the non-destructive characterization of bentonite samples, and the establishment of correlations to obtain physical and mechanical parameters solely from CT images.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 C
• /
• pp.1597-1599
• /
• 2004

Carbon nanotubes (CNTs) are grown on the TiN-coated silicon substrate by varying the thickness of Ni and Invar426 catalyst layers at 600$^{\circ}C$ using an inductively coupled plasma-chemical vapor deposition (ICP-CVD). The Ni and Invar426 catalysts are formed using an RF magnetron sputtering system with various deposition periods. Characterization using various techniques, such as FESEM, HRTEM, and Raman spectroscopy, shows that the physical dimension as well as the crystal quality of grown CNTs are strongly changed by the kind and thickness of catalyst materials. It is also seen that Ni catalysts would be more desirable for vertical-alignment of CNTs compared with Invar426 catalysts. However, the CNTs using Invar426 catalysts display much better electron emission capabilities than those using Ni catalysts. The physical reason for all the measured data obtained are discussed to establish the relationship between structural properties and field-emissive properties of CNTs.

• 한국결정성장학회지
• /
• 제14권4호
• /
• pp.160-168
• /
• 2004

We investigate the effects of solutal convection on the crystal growth rate in a horizontal configuration for diffusive-convection conditions and purely diffusion conditions achievable in a low gravity environment for a nonlinear thermal gradient. It is concluded that the solutally-driven convection due to the disparity in the molecular weights of the component A $(Hg_2Br_2)$ and B (CO) is stronger than thermally-driven convection for both the nonlinear and the linear thermal profiles, corresponding to $Gr_t= 8.5{\times}10^3,\; Gr_s = 1.05{\times}10^5$. For both solutal and thermal convection processes, the growth rates for the linear thermal profile (conducting walls) are greater than for the nonlinear case. With the temperature humps, there are found to be observed in undersaturation for diffusive-convection processes ranging from $D_{AB}$ = 0.087 to 0.87. For the vertical configurations, the diffusion mode is so much dominated that the growth rate and interfacial distribution is nearly regardless of the gravitational accelerations. Also, the diffusion mode is predominant over the convection for the gravity levels less than 0.1 $g_0$ for the horizontally oriented configuration.

• 한국세라믹학회지
• /
• 제46권1호
• /
• pp.94-101
• /
• 2009

The physical properties of artificial aggregates made from clay and inorganic wastes with poor plasticity depends largely on forming method. The artificial aggregates composing of coal fly ash, stone sludge and clay were fabricated using 4 different forming methods and those physical properties were comparatively analyzed. The surface of aggregates made through the extrusion forming process was dense and smooth but was rough for the aggregates obtained by crushing a tile-shaped green body. The aggregates made by pelletizing process had a weak green strength and bumpy surface. The shell generated at surface during a high temperature sintering process induced the most aggregates to be bloated due to a dense shell. But the aggregates made through pelletizing process with dense surface layer showed no significant change in bulk density with sintering temperatures. The water absorption of aggregates decreased with sintering temperature, and that of pelletized specimen was standing $1.8{\sim}2.2$ times higher than that of made by other forming methods. It is concluded that the aggregates having various properties could be fabricated from one batch by using different forming methods.