• Advances in concrete construction
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• v.9 no.2
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• pp.217-225
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• 2020

The recovery of waste proves a solution with two impacts: the environmental impact by the reduction of pollution and the gain of the occupied space by this waste, and the economic impact by the use of these lasts in the building and in the area of public works. The present research consists in recovering a waste marble (thrown powder exposed to the different meteorological phenomena) generated by the quarry marble of Fil-fila, located at the east side of Skikda in the north-east of Algeria, and add it, as sand in the composition of sand concrete. To carry out this research, we analyzed the evolution brought by the substitution of ordinary sand by marble waste sand, with 25%, 50%, 75% and 100% on the properties in the fresh state (density, workability and air content) and in the cured state (compressive strength, tensile strength, surface hardness and sound velocity). For durability we tested water absorption by immersion and chloride penetration. The results obtained are compared with control samples of 0% of substitution rate. In order to have a good filling of the voids in the granular skeleton; we added a quantity of limestone recycled fines from the quarries and for a good workability a super-plasticizing additive. The results showed that the partial substitution modified both the fresh and the hardened characteristics of the tested concretes, the durability parameters also improved.

• KIEAE Journal
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• v.7 no.5
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• pp.135-142
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• 2007

This is an experimental study on the structural characteristics of reinforced concrete beams using of the oyster shells as a substitute fine aggregate of concrete. In this study, the main factors consist of the grain sizes and the percentage of substitution of oyster shells to fine aggregate in the equal water cement ratio. The results of the study showed as followed. The initial load value of them represented similar constant within 10% of the maximum load value in each test beam. But the maximum load value and the ultimate load value decreased with increased grain size and the rate of substitution. As the grain size of oyster shells became smaller, the load values of them were somewhat higher. The deflection among deformation properties of reinforced concrete beams with oyster shells represented typical curves like that of normal reinforced concrete. In the deformation of steel and concrete, the deformation was proportionated to the load till yield point and from yield point until approaching the ultimate load point. One type was typical curve of the load and the deformation and the other type irregularly was changed to very small deformation for the load increase centering around load axis. After the analyzing structural behaviors and the properties of reinforced concrete test beams with oyster shells, the most excellent grain size of oyster shells represented 1.0mm and less or 5.0mm and less with taking uniformly, and the percentage of practicable substitution of them to fine aggregate was about 30%.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.1
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• pp.29-37
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• 2004

The effect of the substitution of Tungsten(W) for Molybdenum(Mo) on the creep behaviour of 22Cr-5Ni duplex stainless steel(DSS) has been investigated. Creep tests were carried out at $600^{\circ}C\;and\;650^{\circ}C$. Intermetallic ${\sigma}$ phase is precipitated during creep at $650^{\circ}C$, at which creep rupture time was much lower compared with at $600^{\circ}C$. The substitution of W for Mo in the duplex stainless steel was known to retard the formation of ${\sigma}$ phase. Minimum creep rate and creep rupture time, however, were hardly influenced by the substitution of 2wt.% W. An ultrasonic measurement for the creep specimens has been carried out for the evaluation of creep damage. The sound velocity increases propotionally with the increase of creep rupture time at $600^{\circ}C$ of creep temperature. On the contrary, the sound velocity decreases with the increase of rupture time at $650^{\circ}C$, which can be correlated with the microstructural evolution during creep.

• Journal of KIISE:Software and Applications
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• v.34 no.7
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• pp.595-602
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• 2007

This paper proposes a method that discriminates signal peptide and predicts the cleavage site of the secretory proteins cleaved by the signal peptidase I. The preprocessing stage uses hydrophobicity scales of amino acids in order to predict the presence of signal sequence and the cleavage site. The preprocessing enhances the performance of the prediction method by eliminating the non-secretory proteins in the early stage of prediction. for the effective use of support vector machine for the signal sequence prediction, the biologically relevant distance between the amino acid sequences is defined by using the hydrophobicity and substitution matrix; the hydrophobicity can be used to Predict the location of amino acid in a cell and the substitution matrix represents the evolutionary relationships of amino acids. The proposed method showed 98.9% discrimination rates from signal sequences and 88% correct rate of the cleavage site prediction on Swiss-Prot release 50 protein database using the 5-fold-cross-validation. In the comparison tests, the proposed method has performed significantly better than other prediction methods.

• Analytical Science and Technology
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• v.17 no.5
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• pp.375-380
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• 2004

Kinetics have been studied by high vacuum and high pressure apparatus under various temperatures and pressures for the nucleophilic substitution reaction. Rate constants, activated parameters and Hammett ${\rho}$-values are determined. The values of ${\Delta}V^{\ddag}$, ${\Delta}{\beta}^{\ddag}$ and ${\Delta}S^{\ddag}$ are all negative. The Hammett ${\rho}$-values are negative for the nucleophile (${\rho}x$) over the pressure range studied. Consequently the rate constant increases as the pressure increases, and some decrease in vacuum. So these reactions proceed in typical $S_N2$ reaction mechanism.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.40-41
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• 2018

The purpose of this study is to compare the amount of critical chloride of rebar embedded in concrete according to the substitution rate of admixture. In order to determine the starting point of corrosion of rebar, electrodes were embedded in concrete, chloride was supplied, and OCP of rebar was observed in real time. The amount of the contaminants in the concrete surrounding the rebar was judged to be the critical corrosion chloride contents of the rebar at the start of the corrosion. As a result of the comparative evaluation, it was confirmed that the critical chloride contents of the rebar decreased with increasing the substitution ratio of the admixture.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2801-2805
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• 2010

A nucleophilic substitution reaction of 4-chloro-7-nitrobenzofurazan (NBF-Cl) with anilines in MeOH-MeCN mixtures was conducted at 25, 35, and $45^{\circ}C$. Based on the higher $\beta_{nuc}$ values (1.0 - 1.6) of the reaction and a good correlation of the rate constants with the reduction potentials of the aniline nucleophiles, the present reaction was initiated by a single electron transfer (SET). After this step, the reaction proceeds through a transition state similar to the normal $S_NAr$-Ad.E pathway.

• Mycobiology
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• v.33 no.2
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• pp.109-112
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• 2005

The internal transcribed spacer (ITS) regions including the 3'-end of 18S rRNA gene, 5.8S rRNA gene and the 5'-end of the 28S rRNA gene of Rhizopus spp. were amplified by PCR and analyzed by DNASIS program. Length polymorphism of these region ranged from 564 bp in R. oryzae to 789bp in R. stolonifer. The length and sequence of 5.8S was very conserved with $154{\sim}155\;bp$. The sequence of ITS2 was more variable than that of ITS1. The base substitution rates were ranged from 0 to 0.6069 per site, and higher rate was found in R. stolonifer. In general, transition was usually more frequent than transversion. On the basis of sequencing results, four groups were clustered with value of 61.9% similarity; R. oryzae, R. micros pores, R. homothallicus, and R. stolonifer groups.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.3
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• pp.299-303
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• 2004

A systematic investigation for the reactivity and solvent effect was studied on the reaction of optical resolving agents with the optically active assistant compounds. The reaction rate constants of the nucleophillic substitution reactions were determined by means of conductometric method The linear solvent energy relationship based on the solvent parameters and the thermodynamic parameters was discussed on the reactions of various physiological active compounds and optical resolving agents The reaction mechanism was discussed from the kinetic results compared with the optical purity.

• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.654-658
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• 1994

Rate constants have been measured spectrophotometrically for the nucleophilic substitution reactions of p-and m-nitrophenyl 2-furoates (4 and 5, respectively) with alkali metal ethoxides ($EtO^-M^+$) in absolute ethanol at 25$^{\circ}$C. The reactivity of $EtO^-M^+$ toward 4 is in the order $EtO^-K^+$ > $EtO^-Na^+$> $EtO^-Li^+$ > $EtO^-K^+$+ 18-crown-6 ether. This is further confirmed by an ion pairing treatment method. The present result indicates that (1) ion paired $EtO^-M^+$ is more reactive than dissociated $EtO^-$ ; (2) the alkali metal ions ($K^+,\;Na^+,\;Li^+$) behave as a catalyst; (3) the catalytic effect increases with increasing the size of the metal ion. A similar result has been obtained for the reaction of 5, however, the catalytic effects shown by the metal ions are more significant in the reaction of 5 than in that of 4.