• Journal of Microbiology and Biotechnology
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• v.31 no.7
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• pp.967-977
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• 2021

A total of 37 bacterial isolates were obtained from dye-contaminated soil samples at a textile processing factory in Nakhon Ratchasima Province, Thailand, and the potential of the isolates to decolorize and biotransform azo dye Reactive Red 141 (RR141) was investigated. The most potent bacterium was identified as Paenibacillus terrigena KKW2-005, which showed the ability to decolorize 96.45% of RR141 (50 mg/l) within 20 h under static conditions at pH 8.0 and a broad temperature range of 30-40℃. The biotransformation products were analyzed by using UV-Vis spectrophotometry and Fourier-transform infrared spectroscopy. Gas chromatography-mass spectroscopy analysis revealed four metabolites generated from the reductive biodegradation, namely sodium 3-diazenylnaphthalene-1,5-disulfonate (I), sodium naphthalene-2-sufonate (II), 4-chloro-1,3,5-triazin-2-amine (III) and N¹-(1,3,5-triazin-2-yl) benzene-1,4-diamine (IV). Decolorization intermediates reduced phytotoxicity as compared with the untreated dye. However, they had phytotoxicity when compared with control, probably due to naphthalene and triazine derivatives. Moreover, genotoxicity testing by high annealing temperature-random amplified polymorphic DNA technique exhibited different DNA polymorphism bands in seedlings exposed to the metabolites. They compared to the bands found in seedlings subjected to the untreated dye or distilled water. The data from this study provide evidence that the biodegradation of Reactive Red 141 by P. terrigena KKW2-005 was genotoxic to the DNA seedlings.

• Journal of Forest and Environmental Science
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• v.37 no.2
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• pp.116-127
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• 2021

Predicting carbon distribution of soil aggregates is difficult due to complexity in organo-mineral formation. This limits global warming mitigation through soil carbon sequestration. Therefore, knowledge of land use effect on carbon stabilization requires quantification of soil mineral cations. The study was conducted to quantify carbon and base cations on soil mineral fractions in Natural Forest, Plantation Forest and Farm Land. Five 0.09 ha were demarcated alternately along 500 m long transect with an interval of 50 m in Natural Forest (NF), Plantation Forest (PF) and Farm Land (FL). Soil samples were collected with soil cores at 0-15, 15-30 and 30-45 cm depths in each plot. Soil core samples were oven-dried at 105℃ and soil bulk densities were computed. Sample (100 g) of each soil core was separated into >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.05 and <0.05 mm aggregates using dry sieve procedure and proportion determined. Carbon concentration of soil aggregates was determined using Loss-on-ignition method. Mineral fractions of soil depths were obtained using dispersion, sequential extraction and sedimentation methods of composite soil samples and sieved into <0.05 and >0.05 mm fractions. Cation exchange capacity of two mineral fractions was measured using spectrophotometry method. Data collected were analysed using descriptive and ANOVA at α_0.05. Silt and sand particle size decreased while clay increased with increase in soil depth in NF and PF. Subsoil depth contained highest carbon stock in the PF. Carbon concentration increased with decrease in aggregate size in soil depths of NF and FL. Micro- (1-0.5, 0.5-0.05 and <0.05 mm) and macro-aggregates (>2.0 and 2-1.0 mm) were saturated with soil carbon in NF and FL, respectively. Cation exchange capacity of <0.05 mm was higher than >0.05 mm in soil depths of PF and FL. Fine silt (<0.05 mm) determine the cation exchange capacity in soil depths. Land use and mineral size influence the carbon and cation exchange capacity of Gambari Forest Reserve.

• Korean Journal of Materials Research
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• v.31 no.7
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• pp.420-426
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• 2021

Graphene, a new material with various advantageous properties, has been actively used in various fields in recent years. Applications of graphene oxide are increasing in combination with other materials due to the different properties of graphene oxide, depending on the number of single and multiple layers of graphene. In this study, single-layer graphene oxide and multi-layer graphene oxide are spray coated on polystyrene, and the physicochemical properties of the coated surfaces are characterized using SEM, Raman spectroscopy, AFM, UV-Vis spectrophotometry, and contact angle measurements. In single-layer graphene oxide, particles of 20 ㎛ are observed, whereas a 2D peak is less often observed, and the difference in surface height increases according to the amount of graphene oxide. Adhesion increases with an increase in graphene oxide up to 0.375 mg, but decreases at 0.75 mg. In multi-layer graphene oxide, particles of 5 ㎛ are observed, as well as a 2D peak. According to the amount of graphene oxide, the height difference of the surface increases and the adhesive strength decreases. Both materials are hydrophilic, but single-layer graphene oxide has a hydrophilicity higher than that of multi-layer graphene oxide. We believe that multi-layer graphene oxide and single-layer graphene oxide can be implemented based on the characteristics that make them suitable for application.

• International Journal of Oral Biology
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• v.45 no.4
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• pp.143-151
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• 2020

Streptococcus mutans and Streptococcus sobrinus play important roles in dental caries. Coptis chinensis is a natural product with antimicrobial activity against enterobacteria; however, its effects on oral streptococci are still unknown. Therefore, the effects of C. chinensis on the growth and biofilm formation of the representative cariogenic bacteria S. mutans and S. sobrinus were investigated for the possible use of C. chinensis as an anticaries agent. The C. chinensis extract was diluted with sterile distilled water, and 0.1-2.5% of the extract was used in the experiment. The effects of the C. chinensis extract on the growth and glucan formation of S. mutans and S. sobrinus were measured by viable cell counting and spectrophotometry at 650 nm absorbance, respectively. Crystal violet staining was also carried out to confirm the C. chinensis extract's inhibitory effect on biofilm formation. The C. chinensis extract significantly inhibited the growth of S. mutans and S. sobrinus at concentrations of ≥ 0.3% as compared with the control group. The viable cell count of colonies decreased by 1.7-fold and 1.2-fold at 2.5% and 1.25%, respectively, compared with the control group. The biofilm formation of S. mutans and S. sobrinus was inhibited by > 20-fold at C. chinensis extract concentrations of ≥ 1.25% as compared with the control group. In summary, the C. chinensis extract inhibited the growth and biofilm and glucan formation of S. mutans and S. sobrinus. Therefore, C. chinensis might be a potential candidate for controlling dental caries.

• Corrosion Science and Technology
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• v.21 no.6
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• pp.434-444
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• 2022

Corrosion inhibitors based on Zn-Al hydrotalcites containing benzoate (ZnAlHB) with different molar ratios of Zn/Al were prepared with a co-precipitation process. Compositions and structures of the resulting hydrotalcites were studied with suitable spectroscopic methods such as inductively coupled plasma mass spectrometry (ICP-MS), ultraviolet-visible spectrophotometry (UV-Vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and surface zeta potential measurements, respectively. Results of physico-chemical studies showed that crystallite sizes, compositions of products, and surface electrical properties were significantly changed when the molar ratio of Zn/Al was increased. The release of benzoate from hydrotalcites also differed slightly among samples. Anticorrosion abilities of hydrotalcites intercalated with benzoate at a concentration of 3 g/L on carbon steel were analyzed using electrochemical impedance spectroscopy (EIS), polarization curve, energy-dispersive X-ray spectroscopy (EDX), and SEM. Corrosion inhibition abilities of benzoate modified hydrotalcites in 0.1 M NaCl showed an upward trend with increasing Zn/Al ratio. The reason for the dependence of corrosion resistance on the Zn/Al ratio was discussed, including changes in the microstructure of hydrotalcites such as crystal size, density, uniformity, and formation of ZnO.

• Journal of Surface Science and Engineering
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• v.56 no.4
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• pp.233-242
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• 2023

In recent years, energy-management studies in buildings have proven useful for energy savings. Typically, during heating and cooling, the energy from a given building is lost through its windows. Generally, to block the entry of ultraviolet (UV) and infrared (IR) rays, thin films of deposited metals or metal oxides are used, and the blocking of UV and IR rays by these thin films depends on the materials deposited on them. Therefore, by controlling the thicknesses and densities of the thin films, improving the transmittance of visible light and the blocking of heat rays such as UV and IR may be possible. Such improvements can be realized not only by changing the two-dimensional thin films but also by altering the zero-dimensional (0-D) nanostructures deposited on the films. In this study, 0-D nanoparticles were synthesized using a sol -gel procedure. The synthesized nanoparticles were deposited as deep coatings on polymer and glass substrates. Through spectral analysis in the UV-visible (vis) region, thin-film layers of deposited zinc oxide nanoparticles blocked >95 % of UV rays. For high transmittance in the visible-light region and low transmittance in the IR and UV regions, hybrid multiple layers of silica nanoparticles, zinc oxide particles, and fluorine-doped tin oxide nanoparticles were formed on glass and polymer substrates. Spectrophotometry in the UV-vis-near-IR regions revealed that the substrates prevented heat loss well. The glass and polymer substrates achieved transmittance values of 80 % in the visible-light region, 50 % to 60 % in the IR region, and 90 % in the UV region.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.287-295
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• 2023

Iron nanoparticles (Fe-NPs) were synthesized employing Lagenaria siceraria (LS) leaf aqueous extract as a reducing and capping medium to remove methylene blue (MB) dye and have antibacterial properties against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus). The formation of LS-Fe-NPs (Lagenaria-siceraria-iron-nanoparticles) was confirmed by a change in color from pale yellow to dark brown. Characterization techniques, such as particle size analysis (PSA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), were employed to prove nano spherical particles of size range between 80-100 nm. Phytochemicals and the presence of iron in LS-Fe-NPs nanoparticles were proved by UV-visible spectrophotometry. Further, Fourier transform infrared spectroscopy (FTIR) analysis results confirmed the existence of bioactive molecules in the plants. The magnetic property was analyzed using a vibrating sample magnetometer (VSM), which displayed that the synthesized nanoparticles were superparamagnetic and exhibiting a saturation magnetization of 12.5 emu/g. Synthesized magnetic nanoparticles were used in methylene blue (MB) dye removal through adsorption. About 83% of 100 mg/L MB dye was removed within 120 min at pH 6 with a maximum adsorption capacity of 246.8 mg/g. Antibacterial efficacy of LS-Fe-NPs was screened against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus), respectively, and found that LS-Fe-NPs were effective against Staphylococcus aureus.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.3
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• pp.57-63
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• 1986

Atmospheric particulate matter (A.P.M.) was collected on quartz fiber filters from March 1985 to May 1986 according to particle size using Andersen high-volume air sampler, and 6 heavy metals (Fe, Mn, Cu, Ni, Zn, Pb) in these particulates were analyzed by atomic absorption spectrophotometry. The arithmetic mean concentration of A.P.M. was 195.57$\mug/m^3$. The arithmetic mean concentrations of 6 metals (Fe, Mn, Cu, Ni, Zn and Pb) were 3385.04, 1451.67, 897.94, 159.68, 127.14 and 59.49 $ng/m^3$ respectively. The order of heavy metals contributing to A.P.M. was as follows: Fe > Zn > Pb > Cu > Mn > Ni. These heavy metals were devided into 3 groups according to their particle size distribution. The contents of heavy metals belonging to the 1st group (Fe, Mn) were increased with the particle size. On the contrary, the content of Pb belonging to the 2nd group (Pb) was increased with the decrease in the particle size. The heavy metal contents in the 3rd group (Ni, Cu, Zn) were lowest in the particle size range of 2.0-3.3 $\mum$ compared with particles larger or smaller tha this range. The seasonal variation of heavy metal concentration were as follows: Fe and Mn contents were highest in spring, but Ni and Pb contents were highest in winter. Statistical analysis showed that there was a significant correlation between A.P.M. and Fe in coarse particles, meanwhile between A.P.M. and Pb in the case of fine particles.

• Restorative Dentistry and Endodontics
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• v.46 no.4
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• pp.52.1-52.11
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• 2021

Objectives: This study evaluated the effects of low and moderate concentrations of triple antibiotic paste (TAP) and double antibiotic paste (DAP) loaded into a hydrogel system on crown discoloration and explored whether application of an adhesive bonding agent prevented crown discoloration. Materials and Methods: Intact human molars (n = 160) were horizontally sectioned 1 mm apical to the cementoenamel junction. The crowns were randomized into 8 experimental groups (calcium hydroxide, Ca[OH]₂; 1, 10, and 1,000 mg/mL TAP and DAP; and no medicament. The pulp chambers in half of the samples were coated with an adhesive bonding agent before receiving the intracanal medicament. Color changes (ΔE) were detected by spectrophotometry after 1 day, 1 week, and 4 weeks, and after 5,000 thermal cycles, with ΔE = 3.7 as a perceptible threshold. The 1-sample t-test was used to determine the significance of color changes relative to 3.7. Analysis of variance was used to evaluate the effects of treatment, adhesive, and time on color change, and the level of significance was p < 0.05. Results: Ca(OH)₂ and 1 and 10 mg/mL DAP did not cause clinically perceivable tooth discoloration. Adhesive agent use significantly decreased tooth discoloration in the 1,000 mg/mL TAP group up to 4 weeks. However, adhesive use did not significantly improve coronal discoloration after thermocycling when 1,000 mg/mL TAP was used. Conclusions: Ca(OH)₂ and 1 and 10 mg/mL DAP showed no clinical discoloration. Using an adhesive significantly improved coronal discoloration up to 4 weeks with 1,000 mg/mL TAP.

• Restorative Dentistry and Endodontics
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• v.47 no.1
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• pp.8.1-8.9
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• 2022

Objectives: The aim of this study was to compare the color change of the Giomer resin composite (Beautifil-Bulk) by using photographs obtained with a smartphone (iPhone 6S) associated with Adobe Photoshop software (digital method), with the spectrophotometric method (Vita Easyshade) after immersion in different pigment solutions. Materials and Methods: Twenty resin composite samples with a diameter of 15.0 mm and thickness of 1.0 mm were confectioned in A2 color (n = 5). Photographs and initial color readings were performed with a smartphone and spectrophotometer, respectively. Then, samples were randomly divided and subjected to cycles of immersion in distilled water (control), açai, Coke, and tomato sauce, 3 times a day, 20 minutes for 7 days. Later, new photographs and color readings were taken. Results: The analysis (2-way analysis of variance, Holm-Sidak, p < 0.05) demonstrated no statistical difference (p < 0.005) between the methods in all groups. Similar color changes were observed for all pigment solutions when using the spectrophotometric method. For the digital method, all color changes were clinically unacceptable, with distilled water and tomato sauce similar to each other and with statistical differences (p < 0.005) for Coke and açai. Conclusions: Only the tomato sauce produced a color change above the acceptability threshold using both methods of color assessment. The spectrophotometric and digital methods produce different patterns of color change. According to our results, the spectrophotometric method is more recommended in color change assessment.