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( Tridib Ganguly ),( Partho Chattoraj ),( Malabika Das ),( Palas K. Chanda ),( Nitai. C. Mandal ),( Chia Y. Lee ),( Subrata Sau ) 생화학분자생물학회 2004 BMB Reports Vol.37 No.6
The wild-type repressor CI of temperate mycobacteriophage Ll and the temperature-sensitive (ts) repressor CIts391 of a mutant Ll phage, LlcIts391, have been separately overexpressed in E. coli. Both these repressors were observed to specifically bind with the same cognate operator DNA. The operator-binding activity of CIts391 was shown to differ significantly than that of the CI at 32 to 42C. While 40-95% operator-binding activity was shown to be retained at 35 to 42C in CI, more than 75% operator-binding activity was lost in CIts391 at 35 to 38℃, although the latter showed only 10% less binding compared to that of the former at 32℃. The CIts391 showed almost no binding at 42℃. An in vivo study showed that the CI repressor inhibited the growth of a clear plaque former mutant of the L1 phage more strongly than that of the CIts391 repressor at both 32 and 42℃. The half-life of the CIts391-operator complex was found to be about 8 times less than that of the CI-operator complex at 32C. Interestingly, the repressor-operator complexes preformed at 0C have shown varying degrees of resistance to dissociation at the temperatures which inhibit the formation of these complexes are inhibited. The CI repressor, but not that of CIts391, regains most of the DNA-binding activity on cooling to 32C after preincubation at 42 to 52C. All these data suggest that the 131 proline residue at the C-terminal half of CI, which changed to leucine in the CIts391, plays a crucial role in binding the L1 repressor to the cognate operator DNA, although the helix-turn-helix DNA-binding motif of the LI repressor is located at its N-terminal end.
Ganguly, Tridib,Chattoraj, Partho,Das, Malabika,Chanda, Palas K.,Mandal, Nitai.C.,Lee, Chia Y.,Sau, Subrata Korean Society for Biochemistry and Molecular Biol 2004 Journal of biochemistry and molecular biology Vol.37 No.6
The wild-type repressor CI of temperate mycobacteriophage L1 and the temperature-sensitive (ts) repressor CIts391 of a mutant L1 phage, L1cIts391, have been separately overexpressed in E. coli. Both these repressors were observed to specifically bind with the same cognate operator DNA. The operator-binding activity of CIts391 was shown to differ significantly than that of the CI at 32 to $42^{\circ}C$. While 40-95% operator-binding activity was shown to be retained at 35 to $42^{\circ}C$ in CI, more than 75% operator-binding activity was lost in CIts391 at 35 to $38^{\circ}C$, although the latter showed only 10% less binding compared to that of the former at $32^{\circ}C$. The CIts391 showed almost no binding at $42^{\circ}C$. An in vivo study showed that the CI repressor inhibited the growth of a clear plaque former mutant of the L1 phage more strongly than that of the CIts391 repressor at both 32 and $42^{\circ}C$. The half-life of the CIts391-operator complex was found to be about 8 times less than that of the CI-operator complex at $32^{\circ}C$. Interestingly, the repressor-operator complexes preformed at $0^{\circ}C$ have shown varying degrees of resistance to dissociation at the temperatures which inhibit the formation of these complexes are inhibited. The CI repressor, but not that of CIts391, regains most of the DNA-binding activity on cooling to $32^{\circ}C$ after preincubation at 42 to $52^{\circ}C$. All these data suggest that the 131st proline residue at the C-terminal half of CI, which changed to leucine in the CIts391, plays a crucial role in binding the L1 repressor to the cognate operator DNA, although the helix-turn-helix DNA-binding motif of the L1 repressor is located at its N-terminal end.
STUDY ON SEATING COMFORT OF POLYURETHANE MULTILAYER SEAT CUSHIONS
문준호,Tridib Kumar Sinha,곽성복,하진욱,오정석 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.5
Instead of a monolayer, multi-layered cushion can be promising to develop more comfortable automotive seat if the layer materials are properly selected. In this study, we have examined the seating comfort of different types of multilayer seat cushions. Polyurethane foams (PUFs) of three different hardness, memory foam, and technogel were used in different combination to prepare four types of multilayer seat cushions. The short-term seating comfort of the seat cushions has been investigated in terms of hardness, initial hardness factor (IHF), modulus irregularity factor (MIF), sag factor (SF), and hysteresis loss as derived from the indentation force deflection (IFD) curves. Long-term comfort has been compared to the respective stress relaxation behavior of the seat cushions. It has been observed that both the short and long-term conditions of comfort are not only influenced by the characteristics of the upper layer, but also by the bottom layer (i.e., supporting material). The present work will help the seat designer to consider the material characteristics for fabricating a good automotive seat on the basis of the desired features needed to provide traveling passengers with proper short- and long term comfort.
주수현,Tridib Kumar Sinha,문준호,오정석 한국고무학회 2023 엘라스토머 및 콤포지트 Vol.58 No.3
Herein, we propose a facile water-processible method to develop an eggshell membrane (ESM)-embedded waterborne polyurethane (WPU)-based bio-degradable and bio-compatible coating material that exhibits attractive tactile properties. Virgin ESM is not dispersible in water. Hence, to develop the ESM-based WPU composite, soluble ESM (SESM) was first extracted by de-crosslinking the ESM. The extracted S-ESM at different concentrations (0, 0.5, 1.0, 1.5 wt %) was mixed with WPU. Compared to virgin WPU, the viscosity of S-ESM/WPU dispersion and the in-plane coefficient of friction (COF) of the composite film surfaces decreased with an increase in the S-ESM content. In addition, an increase in the S-ESM content improved the tribo-positive characteristics of the film. Different good touch-feeling biomaterials, such as fur, feather, and human skin exhibit tribo-positivity. Thus, the enhanced tribo-positive characteristics of the S-ESM/WPU and the decrease in their COF owing to an increase in the S-ESM content imply the enhancement of its touch-feeling performance. The S-ESM embedded WPU composites have potential applications as coating materials in various fields, including automobile interiors and artificial leather.
Solution Based Epoxidation Towards Facilitating the Production of Epoxidized Isoprene Rubbers
( Xiaojie Zhang ),( Tridib Kumar Sinha ),( Jeong Seok Oh ),( Jin Kuk Kim ) 한국고무학회 2020 엘라스토머 및 콤포지트 Vol.55 No.3
Considering the immense applicability of isoprene rubbers, such as natural rubber (NR) and synthetic polyisoprene rubber (IR), attempts are being made to introduce more functionality within the rubber structure, e.g. epoxidation, to widen their technological viability. Epoxidation introduces polar epoxy bonds into the rubber molecular chain, resulting in enhanced intermolecular interactions among the rubber chains, increasing the oil resistance and air impermeability. Although there have been many reports on the epoxidation of NR in its latex form, there has been no such report using its solid form (or gum), which limits the epoxidation in terms of portability. Furthermore, the gum form has longer lifetime, while the latex form has limited lifetime for its efficient use. In this study, the epoxidation of natural rubber and polyisoprene rubber (using meta-chloroperoxybenzoic acid (mCPBA) as the epoxidizing agent) by dissolving their gum in hexane (i.e., the solution method) have been studied and compared. The effects of the amount of mCPBA, reaction time, and reaction temperature were investigated. The present process is easy and facilitates the epoxidation of rubbers in their solid form; therefore, it can be used for industrial upscaling of epoxidized rubber production.
Qi Chen,Tridib K. Sinha,Huan Li,Wenbo Li,김진국 한국고분자학회 2018 Macromolecular Research Vol.26 No.13
We have designed an efficient wound dressing fabric consisting of physically attached multicompartment (three layers) electrospun nanofibrous mats. Electrospining technique enables abundant porosity and large surface area into the fabric, ensuring enhanced water absorption and cell respiration purposes. Blend of water insoluble, biocompatible, antifungal, bactericidal, and glutinous chitosan with flexible polyethylene oxide (PEO) and herbomettalic mica has been used as the inner layer. Oxygen permeable, tissue compatible, and flexible thermoplastic polyurethane (TPU) has been used as the outer layer. Using some facile chemical approaches, blends of natural polysaccharide pullulan/polyvinyl alcohol (PVA), and in situ polymerized poly (acrylic acid-co-acrylamide)/PVA have been synthesized to fabricate the superabsorbent polymeric materials (SPM) based middle layers of the No. 1 and No. 2 dressings, respectively. The blend ratio, solution viscosity, and electrospinning conditions (i.e., voltage, injection rate, tip-to-collector distance, etc.) have been optimized to prepare each layers of the desired fabrics. Scanning electron microscope (SEM) images, water uptake measurements, and mechanical and thermal properties have been considered to characterize the fabric properties. Because of the more polar functional groups (i.e., -COOH, -CONH2, and -OH) and more crosslinking within the middle layer by glutaraldehyde, No. 2 fabric shows excellent mechanical property (i.e., tensile strength of > 11 MPa), faster (110 seconds) and higher (95%) fluid absorption efficacy, and better reusability (only 16% of water retention after drying for 7 days at room temperature) than No. 1 fabric. No. 1 fabric, in contrast, mainly consisting of H-bonding among the polymers having only -OH functional group, shows < 10 MPa of tensile strength, 75% fluid absorption within 150 seconds and poor reusability (27% of water retention).