• BMB Reports
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• v.36 no.1
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• pp.35-42
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• 2003

Heterocyclic amines (HCAs) are potent mutagens generated during the cooking of meat and fish, and several of these compounds produce tumors in conventional experimental animals. During the past 5 years or so, HCAs have been tested in a number of novel in vivo murine models, including the following: lacZ, lacI, cII, c-myc/lacZ, rpsL, and $gpt{\Delta}$ transgenics, $XPA^{-/-}$, $XPC^{-/-}$, $Msh2^{+/-}$, $Msh2^{-/-}$ and $p53^{+/-}$ knock-outs, Apc mutant mice ($Apc^{{\Delta}716}$, $Apc^{1638N}$, $Apc^{min}$), and $A33^{{\Delta}N{\beta}-cat}$ knock-in mice. Several of these models have provided insights into the mutation spectra induced in vivo by HCAs in target and non-target organs for tumorigenesis, as well as demonstrating enhanced susceptibility to HCA-induced tumors and preneoplastic lesions. This review describes several of the more recent reports in which novel animal models were used to examine HCA-induced mutagenesis and carcinogenesis in vivo, including a number of studies which assessed the inhibitory activities of chemopreventive agents such as 1,2-dithiole-3-thione, conjugated linoleic acids, tea, curcumin, chlorophyllin-chitosan, and sulindac.

• The Journal of Engineering Research
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• v.8 no.1
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• pp.31-50
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• 2006

Shrinkage may cause cracking in concrete. In practice such cracking must be considered in most concrete applications because, under normal conditions, drying of the concrete is unavoidable, and when drying takes place shrinkage occurs. Cracked concrete is an inferior concrete because it is weaker, more permeable, and more susceptible to chemical attack. The development of the strength of LAC with aging depends on a few factors such as type of the cement, W/C ratio, curing conditions and periods. The higher the strength of LAC, the lower the possibility of shrinkage cracking. Hence, the strength of LAC in the hypocaust system depends to a large extent on the effect of cracking decrease of the antifoaming rate to drying shrinkage in cement.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3841-3848
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• 2022

The effect of modifiers on the optical features and radiation defying ability of the Eu³⁺ ions doped multi constituent glasses was examined. XRD has established the amorphous nature of the specimen. The presence of various functional/fundamental groups in the present glasses was analyzed through FTIR spectra. The physical, structural and elastic traits of the glasses were explored. The variation in the structural compactness of the glass structure according to the incorporated modifier was enlightened to describe their suitability for a better shielding media. For the examined glasses, the metallization criterion value varied in the range 0.613-0.692, indicating the non-metallic character of the glasses with possible nonlinear optical applications. The computed elastic moduli expose the Li-containing glass (BTLi:Eu) to be tightly packed and rigid, which is a requirement for a better shielding channel. Furthermore, the optical bandgap and the Urbach energy values are calculated based on the optical absorption spectra. The evaluated bonding parameters revealed the nature of the fabricated glasses covalent. In addition, we investigated the radiation attenuation attributes of the prepared Eu³⁺ ions doped multi constituent glasses using Phy-X software. We determined the linear attenuation coefficient (LAC) and reported the influence of the five oxides Li₂O₃, CaO, BaO, SrO, and ZnO on the LAC values. The LAC varied between 0.433 and 0.549 cm^-1 at 0.284 MeV. The 39B₂O₃-25TeO₂-15Li₂O₃-10Na₂O-10K₂O-1Eu₂O₃ glass has a much smaller LAC than the other glasses.

• Journal of Technologic Dentistry
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• v.46 no.2
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• pp.28-35
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• 2024

Purpose: To evaluate the three-dimensional trueness of upper and lower denture bases produced using a digital light processing (DLP) printer and immersed in a constant-temperature water bath. Methods: An edentulous model was prepared and fitted with denture bases and occlusal rims manufactured using base plate wax. After scanning the model, denture bases, and occlusal rims, complete denture designs were created. Using the designs and a DLP printer, 10 upper and 10 lower complete dentures were manufactured. Each denture was scanned before (impression surface of upper denture base before constant temperature water bath [UBC] and impression surface of lower denture base before constant temperature water bath [LBC] groups) and after (impression surface of upper denture base after constant temperature water bath [UAC] and impression surface of lower denture base after constant temperature water bath [LAC] groups) immersion in the constant-temperature water bath. Scanned files were analyzed by comparing reference and scanned data, with statistical analysis conducted using the Kruskal-Wallis test (α=0.05). Results: Statistical analysis revealed no significant differences between the UBC and LBC groups, nor between the UAC and LAC groups (p>0.05). However, significant differences were observed between the UBC and UAC groups and between the LBC and LAC groups, i.e., before and after the constant-temperature water bath for both maxillary and mandibular denture bases (p<0.05). Conclusion: Denture bases not immersed in the constant-temperature water bath (UBC and LBC groups) exhibited error values within 100 ㎛, whereas those immersed in the water bath (UAC and LAC groups) showed error values exceeding 100 ㎛.

• Environmental Analysis Health and Toxicology
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• v.14 no.1_2
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• pp.1-12
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• 1999

Recently, several new methods for the detection of genetic damages in vitro and in vivo based on molecular biological techniques were introduced according to the rapid progress in toxicology combined with cellular and molecular biology. Among these methods, mouse lymphoma thymidine kanase (tk) gene forward mutation assay, single cell gel electrophoresis (comet assay) and transgenic animal and cell line model as a target gene of lac I (Big Blue) and lac Z (Muta Mouse) gene mutation are newly introduced based on molecular toxicological approaches. The mouse lymphoma tk$\^$+/-/ gene assay (MOLY) using L5178Y tk$\^$+/-/ mouse lymphoma cell line is one of the mammalian forward mutation assays, and has many advantages and more sensitive than hprt assay. The target gene of MOLY is a heterozygous tk$\^$+/-/ gene located in 11 chromosome, so it is able to detect the wide range of genetic changes like point mutation, deletion, rearrangement, and mitotic recombination within tk gene or deletion of entire chromosome 11. The comet assay is a rapid, simple, visual and sensitive technique for measuring and analysing DNA breakages in mammalian cells, Also, transgenic animal and cell line models, which have exogenous DNA incorporated into their genome, carry recoverable shuttle vector containing reporter genes to assess endogenous effects or alteration in specific genes related to disease process, are powerful tools to study the mechanism of mutation in vivo and in vitro, respectively. Also in vivo acridine orange supravital staining micronucleus assay by using mouse peripheral reticulocytes was introduced as an alternative of bone marrow micronucleus assay. In this respect, there was an International workshop on genotoxicity procedure (IWGTP) supported by OECD and EMS (Environmental Mutagen Society) at Washington D. C. in March 25-26, 1999. The objective of IWGTP is to harmonize the testing procedures internationally, and to extend to finalization of OECD guideline, and to the agreement of new guidelines under the International Conference of Harmonization (ICH) for these methods mentioned above. Therefore, we introduce and review the principle, detailed procedure, and application of MOLY, comet assay, transgenic mutagenesis assay and supravital staining micronucleus assay.

• Korean journal of food and cookery science
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• v.7 no.2
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• pp.89-95
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• 1991

The effects of lactic acid bacteria on the chemical and microbial changes of fermented kimchi at various temperatures were studied. Kimchi was homogenized and was sterilized by ultra violet (UV), then Lactobacillus plantarum, Leuconostoc mesenteroides, Pediococous acidilactici, Lactobacillus brevis and the mixture of these bacteria inoculated on sterilized kimchi, respectively. The measurement of alcohol by gas chromatography, and changes of sugar content and total viable count were investigated and palatability test was carried while inoculated kimchi was fermented at $30^{\circ}C$, $21^{\circ}C$ and $7^{\circ}C$. Ethyl alcohol was detected by GC in sample I (original Kimchi homogenate), III(inoculated Leu. mesenteroides), V(inoculated with Lac. brevis), then especially, more content were detected at $14^{\circ}C$. Sugar content reduced in accordance with fermentation proceeding. Total viable count increased at early fermentation stage, but thereafter decreased slowly. In the result of palatability test, sample I was the highest at all temperatures, sample III and IV (inoculated with mixed lactic acid bacteria) was the following in that kimchi odor and taste and the temperature.

• Korean Journal of Microbiology
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• v.29 no.6
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• pp.392-396
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• 1991

Mu d1(Ap lac) bacteriophage can be used to search for genes which are members of a common regulatory network without having to know the functions of the genes in advance. Aim was for obtaining the loci in the SOS network as well as temperature inducible loci. For this purpose, recA441 allele was used. This allele encodes a thermosensitive recA gene product; thus, the recA441 allele can be activated upon temperature upshift without by external DNA damage. Approximately 10, 000 colonies were screened, and then searched for the colonies which expressed .betha.-galactosidase higher level at 42.deg.C than at 30.deg.C. The strains identified fell into two dlasses; (i) ones in which the increased expression was $recA^{+}$ $lexA^{+}$ -dependent, that is, din(damage-inducible) genes which were due to the activation of recA441 allele and (ii) ones in which the increased expression was $recA^{+}$ $lexA^{+}$ -independent and only temperature-inducible, tin genes. Rough mapping position was obtained for these genes.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2000-2010
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• 2021

Mechanical moduli, such as Young's modulus (E), Bulks modulus (B), Shear modulus (S), longitudinal modulus (L), Poisson's ratio (σ) and micro Hardness (H) were theoretically calculated for (100-x)TeO₂+x MgO glasses, where x = 10, 20, 30, 40 and 45 mol%, based on the Makishima-Mackenzie model. The estimated results showed that the mechanical moduli and the microhardness of the glasses were improved with the increase of the MgO contents in the TM glasses, while Poisson's ratio decreased with the increase in MgO content. Moreover, the radiation shielding capacity was evaluated for the studied TM glasses. Thus, the linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), transmission factor (TF) and half-value thickness (𝚫_0.5) were simulated for gamma photon energies between 0.344 and 1.406 MeV. The simulated results showed that glass TM10 with 10 mol % MgO possess the highest LAC and varied in the range between 0.259 and 0.711 cm^-1, while TM45 glass with 45 mol % MgO possess the lowest LAC and vary in the range between 0.223 and 0.587 cm^-1 at gamma photon energies between 0.344 and 1.406 MeV. Furthermore, the BXCOM program was applied to calculate the effective atomic number (Z_eff), equivalent atomic number (Z_eq) and buildup factors (EBF and EABF) of the glasses. The effective removal cross-section for the fast neutrons (ERCSFN, ∑_R) was also calculated theoretically. The received data depicts that the lowest ∑_R was achieved for TM10 glasses, where ∑_R = 0.0193 cm² g^-1, while TM45 possesses the highest ERCSFN where ∑_R = 0.0215 cm² g^-1.

• The Journal of Natural Sciences
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• v.5 no.1
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• pp.37-45
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• 1992

The gene coding for $\beta$-galactosidase of Neisseria lactamica 2118 was cloned into Escherichia coli MC 1061. The isolated 6.5 Kb EcoR I fragement and 7.2 Kb BamH I fragment of chromosomal DNA in Southern hybridization were ligated to a vector plasmid pBR322 and then transformed into Escherichia coli MC 1061 cells. Finally, I obtained three clones as $\beta$-galactosidase positive clone by colony hybridization and Southern hybridization($\beta$-galactosidase probe: lac Z gene of pMC1871). Three recombinant plasmids(pNL.13. 17 and 24) were found to contain the 7.2Kb BamH I fragment originated from Neisseria lactamica 2118 chromosomal DNA by Southern hybridization and pNL 24 was showed high homology to probe especially and also its physical map was constructed.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1997.12a
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• pp.103-103
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• 1997