A note on proof of Gordon's Conjecture

Kun Du 대한수학회 2018 대한수학회보 Vol.55 No.3

In this paper, we show a proof of Gordon's Conjecture by using Qiu's labels and two new labels.

Biomimetic Designing of Functional Silk Nanotopography Using Self-assembly

Kundu, Banani,Eltohamy, Mohamed,Yadavalli, Vamsi K.,Kundu, Subhas C.,Kim, Hae-Won American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.42

<P>In nature inorganic organic building units create multifunctional hierarchical architectures. Organic silk protein is particularly attractive in this respect because of its micro-nanoscale structural blocks that are attributed to sophisticated hierarchical assembly imparting flexibility and compressibility to designed biohybrid materials. In the present study, aqueous silk fibroin is assembled to form nano/microtopography on inorganic silica surface via a facile diffusion-limited aggregation process. This process is driven by electrostatic interaction and only possible at a specified aminated surface chemistry. The self-assembled topography depends on the age and concentration of protein solution as well as on the surface charge distribution of the template. The self-assembled silk trails closely resemble natural cypress leaf architecture, which is considered a structural analogue of neuronal cortex. This assembled surface significantly enhances anchorage of neuronal cell and cytoskeletal extensions, providing an effective nano/microtopographical cue for cellular recognition and guidance.</P>

Template mediated protein self-assembly as a valuable tool in regenerative therapy

Kundu, B,Eltohamy, M,Yadavalli, VK,Reis, RL,Kim, HW Institute of Physics Publishing Ltd 2018 Biomedical Materials Vol.13 No.4

Environmentally benign and cost-effective synthesis of water soluble red light emissive gold nanoclusters: selective and ultra-sensitive detection of mercuric ions

Kundu, Aniruddha,Park, Byeongho,Ray, Chaiti,Oh, Juyeong,Jun, Seong Chan The Royal Society of Chemistry 2019 NEW JOURNAL OF CHEMISTRY Vol.43 No.2

<P>Heavy metal pollution is a potential threat because it exerts severe harmful effects on the environment and human health. Hence, the rational design and fabrication of fluorescent probes for the simple, selective, and sensitive detection of heavy metal ions are of great significance. In this article, we have reported an environmentally benign, green and cost-effective approach for the synthesis of red luminescent gold nanoclusters (AuNCs) using wheat flour as the stabilizing and capping agent. The resultant AuNCs have been characterized by several spectroscopic and microscopic techniques. We have achieved a high quantum yield (9.02%) for the red fluorescent AuNCs, with a maximum emission wavelength of ∼640 nm under 370 nm excitation. We have successfully applied the synthesized AuNCs for the nanomolar detection of Hg<SUP>2+</SUP> in an aqueous medium <I>via</I> selective fluorescence quenching of the AuNCs in the presence of several other metal ions. We have attained a limit of detection (LOD) as low as 7 nM for Hg<SUP>2+</SUP> and the selectivity of detection is attributed to the specific interaction between the Hg<SUP>2+</SUP> ions and the Au<SUP>+</SUP> ions present in the AuNCs.</P>

Bioethanol production from deacetylated yellow poplar pretreated with oxalic acid recovered through electrodialysis

Kundu, Chandan,Jeong, So-Yeon,Lee, Jae-Won Elsevier 2016 Bioresource technology Vol.208 No.-

<P><B>Abstract</B></P> <P>Electrodialysis (ED) was used to develop a multistage oxalic acid recovery and pretreatment system to produce ethanol from deacetylated yellow poplar. Pretreatment of the biomass was performed at 150°C for 42min using 0.16M oxalic acid. The efficiency of oxalic acid recovery from the hydrolysate reached up to 92.32% in all the stages. Ethanol production and ethanol yield of ED-treated hydrolysate in each stage showed a uniform pattern ranging from 6.81g/L to 7.21g/L and 0.40g/g to 0.43g/g, respectively. The results showed that efficiency of ethanol production increased when deacetylated biomass and ED process was used. Ethanol yield from the pretreated biomass using simultaneous saccharification and fermentation (SSF) was in the range of 80.59–83.36% in all the stages. The structural characterization of the pretreated biomass at each stage was investigated and structural changes were not significantly different among the various pretreated biomass.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxalic acid was effectively recovered by electrodialysis (ED). </LI> <LI> Reuse of oxalic acid recovered through ED was effective during multistage process. </LI> <LI> The properties of pretreated biomass on multistage process were stable and constant. </LI> <LI> Ethanol production on multistage process was stable and constant. </LI> <LI> Ethanol production increased when deacetylated biomass and ED process were used. </LI> </UL> </P>

Epigallocatechin Gallate Inhibits Phorbol Ester-Induced Activation of NF- B and CREB in Mouse Skin: Role of p38 MAPK

KUNDU, J. K.,SURH, Y.-J. Wiley (Blackwell Publishing) 2007 Annals of the New York Academy of Sciences Vol.1095 No.1

<P>The modulation of intracellular signaling network involved in an inappropriate expression of cyclooxygenase-2 (COX-2) is a pragmatic approach for chemoprevention with a wide variety of dietary phytochemicals. Epigallocatechin gallate (EGCG), a major green tea polyphenol, is one of the most extensively investigated chemopreventive agents. Our previous study revealed that EGCG inhibited expression of COX-2 and activation of mitogen-activated protein kinases (MAPKs) in mouse skin stimulated with a prototype tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA). This study was aimed at identifying transcription factors as molecular targets of EGCG in downregulating COX-2 expression. We found that EGCG inhibited TPA-induced DNA binding of NF-kappaB and CREB in mouse skin in vivo. EGCG also suppressed TPA-induced phosphorylation and subsequent degradation of IkappaBalpha, and prevented nuclear translocation of p65. We also examined whether extracellular signal-regulated protein kinase (ERK) and p38 MAPK, which are known to regulate activation of NF-kappaB, can also modulate CREB DNA binding. Pretreatment with U0126 and SB203580, pharmacological inhibitors of ERK and p38 MAPK, respectively, showed that SB203580, but not U0126, attenuated TPA-induced CREB DNA binding in mouse skin. Taken together, EGCG inhibited TPA-induced DNA binding of NF-kappaB and CREB by blocking activation of p38 MAPK, which may provide a molecular basis of COX-2 inhibition by EGCG in mouse skin in vivo.</P>

Bioethanol production from detoxified hydrolysate and the characterization of oxalic acid pretreated Eucalyptus (Eucalyptus globulus) biomass

Kundu, C.,Lee, J.W. Elsevier 2016 INDUSTRIAL CROPS AND PRODUCTS Vol.83 No.-

<P>In this study, different detoxification treatments (XAD-4 resin adsorption [XAD] and electrodialysis) on oxalic acid pretreated hydrolysate were evaluated. Two different detoxification processes were applied to remove fermentation inhibitors from the oxalic acid pretreated hydrolysate of eucalyptus. The hydrolysates contain sugars (glucose, xylose, and arabinose) and inhibitors. Acetic acid was the main inhibitor in the original hydrolysate, and more total phenolic compounds were generated than hydroxymethyl furfural and furfural. The acetic acid was removed 100% by the electrodialysis process, and total phenolic compounds and furfural were effectively removed from the hydrolysate by XAD. Based on the process order, the combined electrodialysis-XAD process was more effective for ethanol fermentation compared to the combined XAD-electrodialysis process. Ethanol fermentation was successfully performed using the electrodialysis-XAD-treated hydrolysate and achieved a production of 7.83 g/L of ethanol, corresponding to an ethanol yield of 0.40 gig within 48 h. Fourier transform infrared, X-ray diffractometer, and scanning electron microscopy were used to investigate the characteristics of the raw material and pretreated biomass. The results showed that most of the hemicellulose was degraded during oxalic acid pretreatment. Therefore, the crystallinity value increased from 49.79% to 56.93%. The surface of the raw material was smooth, plump, and compact, whereas the pretreated biomass was more fragmented. (c) 2016 Elsevier B.V. All rights reserved.</P>

Geomorphic control on wetland classification: a case study in Himalayan Floodplain region

Kundu Priyanka 대한공간정보학회 2021 Spatial Information Research Vol.29 No.4

Wetland classification is the primary tool to identify and determine wetland landscapes, but it seems to be very difficult as wetlands are the transitional zone between aquatic boundary and terrestrial boundary. Wetlands are also found in different hydroclimatic and topographic settings. Recently ecological wetland classification focuses on hydrogeomorphic unit to know the physical background of the wetland. In most of the cases, the topographic terms like slopes, flats have been given more importance than the geomorphological terms like ox-bow, floodplain. Floodplain wetlands in the Himalayan foothill region are very dynamic in nature. In Tufanganj C.D Blocks of Coochbehar district, many floodplain wetlands are evolved in the form of ox-bow lakes, meander scrolls and paleochannels. These wetland landform adjustments have been taking place as a result of spatio-temporal changes of rivers. The study focuses on the process–landform relationships and timescales of landform adjustments which is helpful for further wetland classification and management. In collaboration with both the participation of geomorphology community in wetland science and awareness by ecology community, characterizing wetlands as dynamic landscapes will be more eminent for wetland research and management.

Studying Water Hydrogen-Bonding Network near the Lipid Multibilayer with Multiple IR Probes

Kundu, Achintya,Verma, Pramod Kumar,Ha, Jeong-Hyon,Cho, Minhaeng American Chemical Society 2017 The Journal of physical chemistry A Vol.121 No.7

<P>A critical difference between living and nonliving is the existence of cell membranes, and hydration of membrane surface is a prerequisite for structural stability and various functions such as absorption/desorption of drugs, proteins, and ions. Therefore, a molecular level understanding of water structure and dynamics near the membrane is important to perceive the role of water in such a biologically relevant environment. In our recent paper [J. Phys. Chem. Lett. 2016, 7, 741] on the IR pump probe study of the OD stretch mode of HDO near lipid multibilayers, we have observed two different vibrational lifetime components of OD stretch mode in the phospholipid multibilayer systems. The faster component (0.6 ps) is associated with OD groups interacting with the phosphate moiety of the lipid, while the slower component (1.9 ps) is due to choline-associated water molecules that are close to bulklike water. Here, we additionally use hydrazoic acid (HN3) as another IR probe of which frequency is highly sensitive to its local H-bonding water density. Interestingly, we found that the vibrational lifetime of the asymmetric azido stretch mode of HN3 in the lipid multibilayer system is similar to that in neat water, whereas its orientational relaxation is a bit slower than that in bulk water. This indicates that due to the tight packing of lipid molecules, particularly the head parts, in the gel phase, HN3 molecules mostly stay near the choline group of lipid and interact with water molecules in the vicinity of choline groups. This suggests that membrane surface-adsorbed molecules such as hydrophilic drug molecules may interact with choline-associated water molecules, when the membrane is in the gel phase, instead of phosphate-associated water molecules.</P>

Unusual fluorescent photoswitching of imidazole derivatives: the role of molecular conformation and twist angle controlled organic solid state fluorescence

Kundu, Anu,Karthikeyan, Subramanian,Sagara, Yoshimitsu,Moon, Dohyun,Anthony, Savarimuthu Philip The Royal Society of Chemistry 2018 Physical Chemistry Chemical Physics Vol.20 No.43

<P>Molecular photoswitching, light induced reversible color/fluorescence modulation, has mostly been realized in organic molecules <I>via E</I>/<I>Z</I> isomerization of azobenzenes and stilbenes and ring opening/closing reactions of spiropyrans and diarylethenes. We report here new fluorescent molecular photoswitches based on triphenylamine (TPA)-imidazole derivatives, <I>N</I>-phenyl-<I>N</I>-(4-(1,4,5-triphenyl-1<I>H</I>-imidazol-2-yl)phenyl)benzenamine (NTPB) and <I>N</I>-phenyl-<I>N</I>-(4-(1-phenyl-1<I>H</I>-phenanthro[9,10-<I>d</I>]imidazol-2-yl)phenyl)benzenamine (NPPB), that exhibited light induced reversible fluorescence switching <I>via</I> conformational change from a twisted molecular structure to more planar. NTPB and NPPB in CHCl3 showed red shift of absorption and fluorescence upon UV light irradiation whereas white light exposure reversed both absorption as well as fluorescence. The role of the TPA-imidazole twisted molecular structure in photoswitching was established based on structure property, computational and photophysical studies. The isobestic point observed in time dependent fluorescence change under UV light irradiation clearly demonstrated the presence of two different conformational isomers. Interestingly, polymorphism and torsion angle (<I>τ</I>) dependent fluorescence of NTPB and NPPB in the solid state also supported the role of the twisted molecular structure of TPA-imidazole in fluorescence switching/tuning. Interestingly, NTPB showed fluorescence photoswitching in the solid state also whereas rigid phenanthrene based NPPB did not show fluorescence photoswitching. Thus the present studies provide structural insight for designing a new type of fluorescent organic molecular photoswitches based on conformational modulation that could be of potential interest in optoelectronic devices.</P>