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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.
A Study on Torrefaction of Sewage Sludge
( Karki Sujeeta ),( Poudel Jeeban ),오세천 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Torrefaction of biomass can produce an energy dense and consistent quality solid biomass fuel for combustion and co-firing applications. This study presents the effects of torrefaction on the basic characteristics of sewage sludge. Sewage sludge was torrefied in a horizontal tubular reactor at temperatures ranging from 200 °C to 550 °C, for heating rates 5, 10 and 15 °C/min. The torrefied sewage sludge was characterized in terms of their elemental composition, energy yield, ash content, and volatile fraction. The gaseous products were also analyzed.
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>
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 Dipesh,Pandeya Bijay,Ghimire Balkrishna 한국생태학회 2023 Journal of Ecology and Environment Vol.47 No.3
Background: Knowledge of the spatial trends of plant invasions in different habitats is essential for a better understanding of the process of these invasions. We examined the variation in invasive alien plant species (IAS) richness and composition at two spatial scales defined by elevation and habitat types (roadside, forest, and cultivated lands) in the Makawanpur district of Nepal. Following an elevation gradient ranging from 500 to 2,400 m asl along a mountain road, plant species cover was recorded within sample plots of size 10 m × 5 m. Systematic random sampling was adopted in every 100 m elevation intervals on three habitat types. Results: Altogether 18 invasive alien plants belonging to eight families were recorded within 60 plots, of which 14 species (representing 80%) were from tropical North and South America. The most common plants by their frequency were Ageratina adenophora, Chromolaena odorata, Bidens pilosa, Lantana camara, and Parthenium hysterophorus. We found a significant relationship between species composition and elevation in the study area. Low-elevation regions had a higher number of alien species as compared to high-elevation regions within different habitat types. Conclusions: The species richness and density of IAS were higher in the road site followed by the cultivated land and forest sites. This pattern occurred throughout the elevation range and habitats. IAS were found mostly in the open land with high sunlight availability. Information from such scientific assessment of invasive alien plants will assist in developing appropriate management plans in the Makawanpur district.
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.