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Evaluation of seismic strengthening techniques for non-ductile soft-story RC frame
Karki, Prajwol,Oinam, Romanbabu M.,Sahoo, Dipti Ranjan Techno-Press 2020 Advances in concrete construction Vol.9 No.4
Open ground story (OGS) reinforced concrete (RC) buildings are vulnerable to the complete collapse or severe damages under seismic actions. This study investigates the effectiveness of four different strengthening techniques representing the local and global modifications to improve the seismic performance of a non-ductile RC OGS frame. Steel caging and concrete jacketing methods of column strengthening are considered as the local modification techniques, whereas steel bracing and RC shear wall systems are selected as the global strengthening techniques in this study. Performance-based plastic design (PBPD) approach relying on energy-balance concept has been adopted to determine the required design force demand on the strengthening elements. Nonlinear static and dynamic analyses are carried out on the numerical models of study frames to assess the effectiveness of selected strengthening techniques in improving the seismic performance of OGS frame.. Strengthening techniques based on steel braces and RC shear wall significantly reduced the peak interstory drift response of the OGS frame. However, the peak floor acceleration of these strengthened frames is amplified by more than 2.5 times as compared to that of unstrengthened frame. Steel caging technique of column strengthening resulted in a reasonable reduction in the peak interstory drift response without substantial amplification in peak floor acceleration of the OSG frame.
Cloning of Tunicamycin Biosynthetic Gene Cluster from Streptomyces chartreusis NRRL 3882
Karki, Suman,Kwon, So-Yeon,Kwon, Hyung-Jin The Korean Society for Applied Biological Chemistr 2011 Applied Biological Chemistry (Appl Biol Chem) Vol.54 No.1
The putative tunicamycin biosynthetic gene cluster was identified in Streptomyces clavuligerus with genome mining approach and this genetic information was used to isolate the tunicamycin biosynthetic gene set from S. chartreusis. Gene inactivation of $tun1_{Sch}$ abolished tunicamycin accumulation in S. chartreusis, confirming that the tunicamycin biosynthetic gene cluster was cloned.
Karki, Suman,Kim, Jin-Yong,Park, Si-Hyung,Kwon, Hyung-Jin The Korean Society for Applied Biological Chemisty 2012 Journal of Applied Biological Chemistry (J. Appl. Vol.58 No.3
GntK harbors methyltransferase-related cobalaminbinding domain and radical S-adenosylmethionine domain. The gntK-inactivation mutant of Micromonospora echinospora accumulated higher levels of gentamicin Cla and lower levels of gentamicin C1 and C2 isomers compared to the wild-type strain. Based on these results, we propose that GntK is involved in Cmethylation on C-6' in gentamicin X2 but is dispensable in gentamicin biosynthesis.
Karki, Sujita,Kesavulu, C.R.,Kim, H.J.,Kaewkhao, J.,Chanthima, N.,Ruangtaweep, Y. Elsevier 2018 Journal of luminescence Vol.197 No.-
<P><B>Abstract</B></P> <P>Silicoborate glasses with composition of (BSYCaSm:(55-x)B<SUB>2</SUB>O<SUB>3</SUB>+ 10SiO<SUB>2</SUB> +25Y<SUB>2</SUB>O<SUB>3</SUB> +10CaO + xSm<SUB>2</SUB>O<SUB>3</SUB>), (where, x= 0.05, 0.10, 0.20, 0.25, 0.30, 0.40, 0.50, mol%) have been synthesized by using the well-known melt quenching technique. The present work deals with physical, optical, photoluminescence, X-ray luminescence and decay time studies of silicoborate glasses. Judd-Ofelt (JO) intensity parameters (Ω<SUB>2,</SUB> Ω<SUB>4</SUB> and Ω<SUB>6</SUB>) and radiative properties for the important luminescent level of Sm<SUP>3+</SUP> ions were derived by using the absorption spectrum of 0.3mol% Sm<SUB>2</SUB>O<SUB>3</SUB> doped glass. The luminescence spectra in the visible region was obtained due to <SUP>4</SUP>G<SUB>5/2</SUB> → <SUP>6</SUP>H<SUB>J</SUB> (5/2, 7/2, 9/2 and 11/2) transition of Sm<SUP>3+</SUP> ion under 401nm excitation. The decay profile for the <SUP>4</SUP>G<SUB>5/2</SUB> level of Sm<SUP>3+</SUP> ions was analyzed and found that for lower concentration (≤ 0.20mol%) it is single exponential in nature whereas for higher concentration (≥ 0.25mol%), it turns in to non-exponential due to the transfer of energy between donor (excited state Sm<SUP>3+</SUP>ion) and acceptor (ground state Sm<SUP>3+</SUP> ion). As the concentration of Sm<SUP>3+</SUP> ions increases the decay time of <SUP>4</SUP>G<SUB>5/2</SUB> state decreases. The well-known Inokuti-Hirayama (IH) model was used for fitting the non-exponential decay curves where S = 6 indicates that energy transfer process is of dipole-dipole type. Hence, in the present work, intense transition of <SUP>4</SUP>G<SUB>5/2</SUB> → <SUP>6</SUP>H<SUB>7/2</SUB> (601nm) is found to be suitable for reddish-orange laser emission. CIE chromaticity diagram has been performed for verifying the results of fluorescence in visible laser applications at 601nm.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Construction of Covalently Linked Caspase-9 Dimer and Its Biochemical Characterization
Karki, Pratap,Dahal, Giri Raj,Park, Il-Seon 朝鮮大學校 附設 醫學硏究所 2007 The Medical Journal of Chosun University Vol.32 No.1
The activation of caspase-9 is best described by induced proximity model that postulates the dimer-driven assembly of monomeric caspase-9 in apoptosome as an activation mechanism. Further, the crystallographic structure of active caspase-9 has shown that termini of monomers lie quite close to each other. With an aim to analyze the role of dimehzation and proteolytic processing in activation, constitutively dimeric forms of caspase-9 were engineered by connecting termini of two caspase-9 molecules. These dimers could be overexpressed and purified in Escherichia coli. The recombinant dimers showed 2-fold increment in specific activity over their respective monomer that was lower than expected if dimerization is the only mechanisJi to activate caspase-9. Citrate, a well-known kosmotrope to enhance dimenzation, increased the activity of wild type monomer and dimer by -75 and -10 times respectively which was -5 times better than that of corresponding uncleavable mutant ones. The possible reason behind this failure of engineered dimers to mimic Apaf-l activated caspase-9 may lie in the distinctly different scenario of dimehzation in two cases or it may be the outcome of the defective design that restricted the complete dimehzation. However, this simple design could enable to produce constitutively dimeric caspase-9 with catalytic advancements over their monomers that may be helpful for future studies to elucidate the molecular mechanism of caspase-9 activation.
Effect of Sowing Time on Germination and Early Seedling Growth of Quercus floribunda Lindl.
Karki, Himani,Bargali, Kiran,Bargali, SS Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.3
Quercus floribunda (Tilonj oak) is among the five species of Quercus and an evergreen tree found in Kumaun Himalayan region. Timing of germination is a crucial event determining the success of seedling establishment and survival. The aims of the study were to investigate the effect of sowing date on the germination and morphological responses of Tilonj oak (Quercus floribunda), cultivated during the month of August-September, with supplementary irrigation. The experiment was conducted by sowing seeds at two dates with one month interval in glass house conditions at DSB Campus, Nainital, Uttarakhand, India. Present study revealed that higher germination percentage (46.67 %) was recorded at sowing time $S_2$ as compared to the sowing time $S_1$ (32.86 %). Germination percentage as well as seedling growth were affected by sowing date though the differences were insignificant. At both the sowing dates, highest germination percentage was recorded for large seeds (32.86-46.67 %) followed by medium (31.43-33.33 %) and lowest germination (6.67-7.14 %) was recorded for small size seeds. In all parameters assessed, sowing time $S_2$ had the best performance in combination with large seed size. Thus, September is suitable month for best germination, growth and seedling vigour and large seed size is recommended to silviculturists and tree planters. The information on seed germination and seedling growth is vital both for conservation and rehabilitation of degraded lands.