Unusually slow proton transfer dynamics of a 3-hydroxychromone dye in protic solvents

Das, Ranjan,Klymchenko, Andrey S.,Duportail, Guy,Mely, Yves Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.11

The photophysics of a 3-hydroxychromone dye, 2-(2-furyl)-3-hydroxychromone (FHC) was explored in different types of protic solvents by steady-state and time-resolved fluorescence spectroscopy. FHC exhibits a dual emission, attributable to the excited normal ($N^*$) and tautomer ($T^*$) forms resulting from an excited state intramolecular proton transfer (ESIPT) reaction ($N^*{\rightarrow}T^*$). The ESIPT rate decreases with an increase in the hydrogen-bond donating ability of protic solvents. The proton-transfer dynamics is found to be unusually slow (${\sim}10^3$ times slower than 3-hydroxyflavone) in strong hydrogen-bond donating solvents like methanol, trifluoroethanol or formamide, where it occurs on a time scale of ~100-260 picoseconds. This slow dynamics is likely to be related to the intermolecular solvent.solute H-bonding interactions that compete with the intramolecular H-bond in FHC required for the ESIPT reaction. These data provide a physical background for recent applications of this dye as a fluorescence probe of the microenvironment in biomolecules.

Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis

Das, Ranjan,Xu, Shanhua,Nguyen, Tuyet Thi,Quan, Xianglan,Choi, Seong-Kyung,Kim, Soo-Jin,Lee, Eun Young,Cha, Seung-Kuy,Park, Kyu-Sang American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.52

<P>TGF-β is a pleiotropic cytokine that accumulates during kidney injuries, resulting in various renal diseases. We have reported previously that TGF-β1 induces the selective up-regulation of mitochondrial Nox4, playing critical roles in podocyte apoptosis. Here we investigated the regulatory mechanism of Nox4 up-regulation by mTORC1 activation on TGF-β1-induced apoptosis in immortalized podocytes. TGF-β1 treatment markedly increased the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream targets p70S6K and 4EBP1. Blocking TGF-β receptor I with SB431542 completely blunted the phosphorylation of mTOR, p70S6K, and 4EBP1. Transient adenoviral overexpression of mTOR-WT and constitutively active mTORΔ augmented TGF-β1-treated Nox4 expression, reactive oxygen species (ROS) generation, and apoptosis, whereas mTOR kinase-dead suppressed the above changes. In addition, knockdown of mTOR mimicked the effect of mTOR-KD. Inhibition of mTORC1 by low-dose rapamycin or knockdown of p70S6K protected podocytes through attenuation of Nox4 expression and subsequent oxidative stress-induced apoptosis by TGF-β1. Pharmacological inhibition of the MEK-ERK cascade, but not the PI3K-Akt-TSC2 pathway, abolished TGF-β1-induced mTOR activation. Inhibition of either ERK1/2 or mTORC1 did not reduce the TGF-β1-stimulated increase in Nox4 mRNA level but significantly inhibited total Nox4 expression, ROS generation, and apoptosis induced by TGF-β1. Moreover, double knockdown of Smad2 and 3 or only Smad4 completely suppressed TGF-β1-induced ERK1/2-mTORactivation. Our data suggest that TGF-β1 increases translation of Nox4 through the Smad-ERK1/2-mTORC1 axis, which is independent of transcriptional regulation. Activation of this pathway plays a crucial role in ROS generation and mitochondrial dysfunction, leading to podocyte apoptosis. Therefore, inhibition of the ERK1/2-mTORC1 pathway could be a potential therapeutic and preventive target in proteinuric and chronic kidney diseases.</P>

Molecular Investigation of Isocitrate Dehydrogenase Gene (IDH) Mutations in Gliomas: First Report of IDH2 Mutations in Indian Patients

Ranjan Das, Bibhu,Tangri, Rajiv,Ahmad, Firoz,Roy, Arnab,Patole, Kamlakar Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.12

Recent genome wide sequencing has identified mutations in IDH1/IDH2 predominantly in grade II-III gliomas and secondary glioblastomas which are associated with favorable clinical outcome. These mutations have become molecular markers of significant diagnostic and prognostic relevance in the assessment of human gliomas. In the current study we evaluated IDH1 (R132) and IDH2 (R172) in 32 gliomas of various grades and tumor subtypes. Sequencing analysis revealed R132H mutations in 18.7% tumors, while none of the cases showed IDH2 (R172) mutations. The frequency of IDH1 mutations was higher in females (21.4%) than males (11.1%), and it was significantly higher in younger patients. Histological analyses demonstrated presence of necrosis and micro vascular proliferation in 69% and 75% respectively. Interestingly, IDH1 mutations were predominantly present in non-necrotic tumors as well as in cases showing microvascular proliferation. Of the six IDH1 positive cases, three were glioblastomas (IV), and one each were anaplastic oligoastrocytoma (III), anaplastic oligodendroglioma III (n=1) and diffuse astrocytoma. In conclusion, IDH1 mutations are quite frequent in Indian glioma patients while IDH2 mutations are not observed. Since IDH mutations are associated with good prognosis, their use in routine clinical practice will enable better risk stratification and management of glioma patients.

혼합 폐 전지로부터 용매추출을 이용하여 회수된 Zn와 Mn Cd 용액 내 Zn power를 이용한 Cd의 제거

( Bikash Ranjan Das ),주성호,신동주,오창현,왕제필,신선명 한국폐기물자원순환학회(구 한국폐기물학회) 2014 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2014 No.-

폐 전지로부터 유가금속을 회수하는 연구는 환경적인 측면뿐만 아니라 광석 보다 높은 품위의 유가금속을 함유하고 있기 때문에 경제적인 측면에서도 상당히 중요하다. 따라서 본 연구는 폐 혼합전지 내 유가금속 중 Mn과 Zn의 회수와 Cd의 제거에 대한 연구를 수행하였다. 폐 혼합전지의 조성은 질량비로 40%알카라인·망간전지, 30%리튬이온전지, 10% 리튬 1차전지, 10% 니켈-카드뮴 전지, 10% 니켈 수소전지를 혼합하였다. 이로부터 물리적 전처리 및 불순물의 제어 후 Zn와 Mn 그리고 Cd을 동시에 회수하기 위한 용매추출 연구를 수행하였다. 그 결과 최적 조건은 용매인 D2EHPA 농도 27%(vol.), 비누화도 45%, O/A=2에서 Zn와 Mn 그리고 Cd을 전량 회수할 수 있었고, 추출 및 탈거 후 탈거용액 내 Zn power를 투입하여 Cd을 4ppm까지 제어 가능하였다. 따라서 이 연구로부터 혼합전지 내 Zn와 Mn을 동시에 회수할 수 있는 최적 공정을 제시할 수 있을 것이다.

D-10 : 폐 혼합전지로부터 시간에 따른 과분쇄를 통한 유가금속의 농축

( Bikash Ranjan Das ),주성호,신동주,신선명 한국폐기물자원순환학회(구 한국폐기물학회) 2013 한국폐기물자원순환학회 추계학술발표논문집 Vol.2013 No.-

폐 전지로부터 유가금속을 회수하는 연구는 환경적인 측면뿐만 아니라 전지 내 광석 보다 높은 품위의 유가금속을 함유하고 있기 때문에 경제적은 측면에서도 상당히 중요하다. 따라서 본 연구는 폐 전지로부터 유가금속을 회수하기 위해 전처리 공정에서 불순물인 Fe및 Al을 물리적 전처리 과정을 통하여 제거하고 유가금속을 농축하기 위한 연구를 수행하였다. 폐 혼합전지의 조성은 질량비로 40%알카라인·망간 전지, 30%리튬이온전지, 10% 리튬 1차전지, 10% 니켈-카드튬 전지, 10% 니켈 수소전지로써 혼합하였다. 혼합된 폐 전지 내 유가금속의 함량은 각 각 14.45% Fe, 7.79% Al, 2.28% Cu, 1.814% Cd, 8.1% Zn, 9.27% Mn, 8.02% Co, 8.72% Ni, 1.43% Li으로 구성되었다. 실험과정은 열처리, 파·분쇄, 시간에 따른 단체분리 과정으로 진행하였다. 단체 분리시 사용된 mesh는 5, 7, 10, 20, 40, 50, 70 mesh size를 사용하였고 그 결과 20초 과·분쇄 5 mesh 기준으로 Zn, Mn, Co, Ni, Li의 경우 농축율이 각 각 90.83%, 92.82%, 91.87%, 92.61%, 87.07% 달성되었고 불순물인 Fe, Al Cu, Cd가 각 각 83.3%, 82.19%, 27.00%, 16.12% 제거되었다. 따라서 이 후 습식 공정을 응용하여 유가 금속을 분리 및 회수하기 위한 최적의 시료 조성을 획득하였다.

Study of surface roughness and flank wear in hard turning of AISI 4140 steel with coated ceramic inserts

Sudhansu Ranjan Das,Debabrata Dhupal,Amaresh Kumar 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

This experimental investigation deals with dry hard turning of AISI 4140 steel using PVD-TiN coated Al2O3+TiCN mixed ceramic inserts. The combined effect of cutting parameters (cutting speed, feed and depth of cut) on performance characteristics such as surfaceroughness and flank wear is explored by Full factorial design (FFD) and analysis of variance (ANOVA). The results show that feed is theprincipal cutting parameter influencing surface roughness, followed by cutting speed. However, flank wear is affected by the cuttingspeed and interaction of feed-depth of cut, although depth of cut has not been found statistically significant, but flank wear is an increasingfunction of depth of cut. Observations are made on the machined surface, and worn tool by Scanning electron microscope (SEM) toestablish the process. Abrasion was the major wear mechanism found during hard turning within the studied range. The effect of toolwear on surface roughness was also studied. The experimental data were analyzed to predict the optimal range of surface roughness andflank wear. Based on Response surface methodology (RSM), mathematical models were developed for surface roughness (Ra) and flankwear (VB) with 95% confidence level. Finally, under optimum cutting conditions (obtained by response optimization technique), tool lifewas evaluated to perform cost analysis for justifying the economic viability of coated ceramic inserts in hard turning. The estimated machiningcost per part for TiN coated ceramic was found to be lower (Rs. 12.31) because of higher tool life (51 min), which results in thereduction of downtime and increase in savings.

폐 혼합전지로부터 시간에 따른 과분쇄를 통한 유가금속의 농축

BIKASH RANJAN DAS,주성호,신선명,신동주 한국폐기물자원순환학회 2013 한국폐기물자원순환학회 학술대회 Vol.2013 No.2

폐 전지로부터 유가금속을 회수하는 연구는 환경적인 측면뿐만 아니라 전지 내 광석 보다 높은 품위의 유가금속을 함유하고 있기 때문에 경제적은 측면에서도 상당히 중요하다. 따라서 본 연구는 폐 전지로부터 유가금속을 회수하기 위해 전처리 공정에서 불순물인 Fe및 Al을 물리적 전처리 과정을 통하여 제거하고 유가금속을 농축하기 위한 연구를 수행하였다. 폐 혼합전지의 조성은 질량비로 40%알카라인・망간 전지, 30%리튬이온전지, 10% 리튬 1차전지, 10% 니켈-카드튬 전지, 10% 니켈 수소전지로써 혼합하였다. 혼합된 폐 전지 내 유가금속의 함량은 각 각 14.45% Fe, 7.79% Al, 2.28% Cu, 1.814% Cd, 8.1% Zn, 9.27% Mn, 8.02% Co, 8.72% Ni, 1.43% Li으로 구성되었다. 실험과정은 열처리, 파・분쇄, 시간에 따른 단체분리 과정으로 진행하였다. 단체 분리시 사용된 mesh는 5, 7, 10, 20, 40, 50, 70 mesh size를 사용하였고 그 결과 20초 과・분쇄 5 mesh 기준으로 Zn, Mn, Co, Ni, Li의 경우 농축율이 각 각 90.83%, 92.82%, 91.87%, 92.61%, 87.07% 달성되었고 불순물인 Fe, Al Cu, Cd가 각 각 83.3%, 82.19%, 27.00%, 16.12% 제거되었다. 따라서 이 후 습식 공정을 응용하여 유가금속을 분리 및 회수하기 위한 최적의 시료 조성을 획득하였다.

Influence of post-heat treatment over structural network and mechanical properties of carbon (C)-incorporated CVD TiCN thin-film coating

Das Soham,Guha Spandan,Ghadai Ranjan Kr. 한국탄소학회 2023 Carbon Letters Vol.33 No.4

In this experimental work, a p-type c-Si (100) substrate with 8 × 8 × 2 mm dimension was taken for TiCN thin-film coating deposition. The whole deposition process was carried out by chemical vapor deposition (CVD) process. The Si substrate was placed within the CVD chamber at base pressure and process pressure of 0.75 and 500 mTorr, respectively, in the presence of TiO2 (99.99% pure) and C (99.99% pure) powder mixture. Later on, quantity of C powder was varied for different set experiments. The deposition of TiCN coating was carried out in the presence of N2–H2–TiCl4–CH3CN gas mixture and 600 ℃ of fixed temperature. The time for deposition was fixed for 90 min with 10 and 5 ℃ min−1 heating and cooling rate, respectively. Later on, heat treatment process was carried out over these deposited TiCN samples to investigate the changing characteristics. The heat treatment was carried out at 800 ℃ within the CVD chamber in the absence of any gas flow rate. The morphological properties of heat-treated samples have been improved significantly, evidence is observed from SEM and AFM analyses. The structural analysis by XRD has been suggested, upgradation in crystallinity of the heat-treated film as it possessed with sharp and higher intensity peaks. Evidence has been found that the electrochemical properties are enhanced for heat-treated sample. Raman spectroscopy shows that the intensity of acoustic phonon modes predominates the optic phonon modes for untreated samples, whereas for heat-treated samples, opposite trends have been observed. However, significant degradation in mechanical properties for heat-treated sample has been observed compared to untreated sample.

Mantle Cell Lymphoma: A North Indian Tertiary Care Centre Experience

Das, Chandan Krushna,Gogia, Ajay,Kumar, Lalit,Sharma, Atul,Sharma, Mehar Chand,Mallick, Saumya Ranjan Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.10

Background: Mantle cell lymphoma (MCL) is an aggressive non-Hodgkin's lymphoma, with a pathognomonic chromosomal translocation t (11;14). Prognosis is uniformly dismal but there is a paucity of information on MCL from India. Materials and methods: We retrospectively analysed clinicopathological information on all treated patients with MCL at our centre. STATA 14.0 was used for analysis. Survival was assessed by Kaplan-Meier analysis and the Cox's proportional hazards method. Statistical significance was defined as a P value of < 0.05. Results: Fifty-one patients with MCL were reviewed. The median age at presentation was 57.0 years. Extranodal involvement was seen in 39.0 (74.0%) while bone marrow positivity at presentation was found in 27.0 (54.0%). Initial treatment was chemotherapy with or without rituximab. Patients receiving rituximab-based therapy (n = 24) had 5-year progression-free survival (PFS) of 21.0 (88.0%), compared with 14.0 (61.0%) for those not receiving rituximab (n = 23, P = 0.036). Twenty-three patients were alive with a median follow-up of 20.7 months (range 2.5-89.2). PFS at 1 and 2 years was 51.0% and 27.0%, and overall survival (OS) 78.0% and 72.0%, respectively. Use of more than 2.0 lines of therapy, use of bendamustine-rituximab, and high TLC (>10,000.0/cu.mm) significantly affected PFS. Conclusions: In our experience, MCL patients from north India have an early age at presentation. When treated with regimens including rituximab results in an improved response rate and PFS. This study provided comprehensive insights into the treatment of MCL in a developing country.

ASSESSMENT OF GROUNDWATER VULNERABILITY IN WALAWE RIVER BASIN, SRI LANKA

RANJAN PRIYANTHA,GUPTA ASHIM DAS,KAZAMA SO,SAWAMOTO MASAKI 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1