A sub-decadal trend in diacids in atmospheric aerosols in eastern Asia

Kundu, S.,Kawamura, K.,Kobayashi, M.,Tachibana, E.,Lee, M.,Fu, P. Q.,Jung, J. Copernicus GmbH 2016 Atmospheric Chemistry and Physics Vol.16 No.2

<P>Abstract. Change in secondary organic aerosols (SOAs) has been predicted to be highly uncertain in the future atmosphere in Asia. To better quantify the SOA change, we examine the sub-decadal (2001-2008) trend in major surrogate compounds (C2-C10 diacids) of SOA in atmospheric aerosols from Gosan site on Cheju Island, South Korea. The Gosan site is influenced by pollution outflows from eastern Asia. The molecular distributions of diacids were characterized by the predominance of oxalic (C2) acid followed by malonic (C3) and succinic (C4) acids in each year. The seasonal variations in diacids in each year were characterized by the highest concentrations of saturated diacids in spring and unsaturated diacids in winter. The consistent molecular distributions and seasonal variations along with significantly similar air mass transport patterns are indicative of similar pollution sources for diacids in eastern Asia on a sub-decadal scale. However, the intensity of the pollution sources has increased as evidenced by the increases in major diacids at the rate of 3.9-47.4 % per year, particularly in April. The temporal variations in atmospheric tracer compounds (carbon monoxide, levoglucosan, 2-methyltetrols, pinic acid, glyoxylic acid, glyoxal and methylglyoxal) suggest that the increases in diacids are due to enhanced precursor emissions associated with more anthropogenic than biogenic activities followed by the compounds' chemical processing in the atmosphere. The trends in diacids contrast with the reported decreases in sulfate, nitrate and ammonium in recent years in eastern Asia. This study demonstrates that recent pollution control strategies in eastern Asia were not able to decrease organic acidic species in the atmosphere. The increases in water-soluble organic acid fraction could modify the aerosol organic composition and its sensitivity to climate relevant physical properties. </P>

A New Microprocessor Based on Line Arrhythmia Diagnostic System

M. Nasipuri,D. K. Basu,R. Dattagupta,M. Kundu,S. Banerjee 대한전자공학회 1997 TENCON 87 - Computers and Communications Technolog Vol.- No.-

Secrecy performance of a-k-u shadowed fading channel

A.S.M. Badrudduza,S.H. Islam,M.K. Kundu,I.S. Ansari 한국통신학회 2023 ICT Express Vol.9 No.2

In this paper, the physical layer security aspects of a wireless framework over shadowed (AKMS) fading channel are examined by acquiring closed-form novel expressions of average secrecy capacity, secure outage probability (SOP), and strictly positive secrecy capacity. The lower bound of SOP is derived along with the asymptotic expression of SOP at the high signal-to-noise ratio regime in order to achieve secrecy diversity gain. Capitalizing on these expressions, the consequences due to the simultaneous occurrence of fading and shadowing are quantified. Finally, Monte-Carlo simulations are demonstrated to assess the correctness of the expressions.

New indices for wet scavenging of air pollutants (O₃, CO, NO₂, SO₂, and PM₁₀) by summertime rain

Yoo, J.M.,Lee, Y.R.,Kim, D.,Jeong, M.J.,Stockwell, W.R.,Kundu, P.K.,Oh, S.M.,Shin, D.B.,Lee, S.J. Pergamon Press ; Elsevier [distribution] 2014 Atmospheric environment Vol.82 No.-

The washout effect of summertime rain on surface air pollutants (O<SUB>3</SUB>, CO, NO<SUB>2</SUB>, SO<SUB>2</SUB>, and PM<SUB>10</SUB>) has been investigated over South Korea during 2002-2012 using routinely available air-monitored and meteorological data. Three new washout indices for PM<SUB>10</SUB>, SO<SUB>2</SUB>, NO<SUB>2</SUB>, and CO are developed to express the effect of precipitation scavenging on these pollutants. All of these pollutants show statistically significant negative correlations between their concentrations and rain intensity due to washout or convection. The washout effect is estimated for precipitation episodes classified by rain intensity (one set included all episodes and another included a subset of moderate intensity episodes that exclude Changma and typhoons), based on the log-transformed hourly data. The most sensitive air pollutant to the rain onset among these five air pollutants is PM<SUB>10</SUB>. The relative effect of the rainfall washout on the air pollutant concentrations is estimated to be: PM<SUB>10</SUB> > SO<SUB>2</SUB> > NO<SUB>2</SUB> > CO > O<SUB>3</SUB>, indicating that PM<SUB>10</SUB> is most effectively scavenged by rainfall. The analysis suggests that the O<SUB>3</SUB> concentrations may increase due to vertical mixing leading to its downward transport from the lower stratosphere/upper troposphere. The concentrations of CO are reduced, probably due to both the washout and convection. The concentrations of NO<SUB>2</SUB> are affected by the opposing influences of lightning-generation and washout and this are discussed as well.

Spatiotemporal variation of Van der Burgh's coefficient in a salt plug estuary

Shaha, Dinesh Chandra,Cho, Yang-Ki,Kim, Bong Guk,Sony, M. Rafi Afruz,Kundu, Sampa Rani,Islam, M. Faruqul Copernicus GmbH 2017 Hydrology and earth system sciences Vol.21 No.9

<P><p><strong>Abstract.</strong> Salt water intrusion in estuaries is expected to become a serious global issue due to climate change. Van der Burgh's coefficient, <i>K</i>, is a good proxy for describing the relative contribution of tide-driven and gravitational (discharge-driven and density-driven) components of salt transport in estuaries. However, debate continues over the use of the <i>K</i> value for an estuary where <i>K</i> should be a constant, spatially varying, or time-independent factor for different river discharge conditions. In this study, we determined <i>K</i> during spring and neap tides in the dry (&amp;lt;<span class='thinspace'></span>30<span class='thinspace'></span>m⁻³<span class='thinspace'></span>s⁻¹) and wet (&amp;gt;<span class='thinspace'></span>750<span class='thinspace'></span>m⁻³<span class='thinspace'></span>s⁻¹) seasons in a salt plug estuary with an exponentially varying width and depth, to examine the relative contributions of tidal versus density-driven salt transport mechanisms. High-resolution salinity data were used to determine <i>K</i>. Discharge-driven gravitational circulation (<i>K</i><span class='thinspace'></span>∼ 0.8) was entirely dominant over tidal dispersion during spring and neap tides in the wet season, to the extent that salt transport upstream was effectively reduced, resulting in the estuary remaining in a relatively fresh state. In contrast, <i>K</i> increased gradually seaward (<i>K</i><span class='thinspace'></span>∼ 0.74) and landward (<i>K</i><span class='thinspace'></span>∼<span class='thinspace'></span>0.74) from the salt plug area (<i>K</i><span class='thinspace'></span>∼<span class='thinspace'></span>0.65) during the dry season, similar to an inverse and positive estuary, respectively. As a result, density-driven inverse gravitational circulation between the salt plug and the sea facilitates inverse estuarine circulation. On the other hand, positive estuarine circulation between the salt plug and the river arose due to density-driven positive gravitational circulation during the dry season, causing the upstream intrusion of high-salinity bottom water. Our results explicitly show that <i>K</i> varies spatially and depends on the river discharge. This result provides a better understanding of the distribution of hydrographic properties.</p> </P>

The Livelihood of Riverine People in Rural Bangladesh: Insights from climate vulnerable context

M Zulfikar Rahman,Rumpa Rani Kundu,Md. 라미루 라이한,Mohammad Golam Farouque,타미나 첨키,Md Nazirul Islam SARKER,Toshihiro Hattori,허창덕 영남대학교 박정희새마을연구원 2023 새마을학연구 Vol.8 No.1

This study assesses the vulnerabilities and determines the livelihood status of individuals living in riverine areas. Additionally, it explores the relationships between selected characteristics of the riverine population and their vulnerability-based livelihood status. Data were collected from 70 heads of households residing in the Narail district of Bangladesh. To develop a scale for assessing vulnerability, a Focus Group Discussion was conducted to identify potential vulnerability indicators. Pearson's product-moment correlation coefficient (r) was calculated to investigate the connections between respondents' characteristics and their livelihood status within the context of vulnerability. Results revealed that the majority of respondents (90 percent) faced a moderate level of vulnerability in their living conditions. The primary vulnerabilities observed in the area included feelings of insecurity due to unsafe infrastructure, displacement caused by riverbank erosion, and disruptions to income opportunities. Regarding livelihood status, the majority of respondents (82.9%) fell into the medium category. Notably, there was considerable variation in different livelihood assets, with a significant proportion (80%) of respondents having low economic capital. Among the selected characteristics of the riverine population, including household size, household assets, household farm size, annual household income, and credit received, significant positive relationships were found with their vulnerability-based livelihood status. However, no significant relationships were observed between the remaining characteristics, namely age, years of schooling, organizational participation, decision-making ability, innovativeness, and vulnerability-based livelihood status. This study emphasizes the urgent need for interventions to address the vulnerabilities faced by riverine communities, including improving infrastructure safety, reducing riverbank erosion, and developing sustainable earning opportunities.

Bioactivity of two medicinal plant Xylocarpus granatum Koen. (Meliaceae) and Sarcolobusglobosus Wall. (Asclepiadaceae) of Sundarbans mangrove forest

M Alamgir,,MA Rob,DC Kundu,JHK Joy,MM Sarder 경희대학교 융합한의과학연구소 2007 Oriental Pharmacy and Experimental Medicine Vol.7 No.4

Two medicinal plant of Sundarbans mangrove forest has been tested for the evaluation of growth inhibitory and antibacterial activity. The methanol extract of Xylocarpus granatum stem bark showed potent wheat rootlet (IC50 = 0.01 µg/ml) and shoot (IC50 = 0.23 µg/ml) growth inhibitory activity in a concentration related manner. The growth inhibitory activity was markedly decreased in residual methanol extract. The methanol extract showed antibacterial activity (MIC > 3 mg/ml) against Bacillus subtilis, Staphylococcus aureous and Proteus vulgaris. The residual methanol extract did not show any antibacterial activity. The results suggest the bioactive principle(s) of Xylocarpus granatum may be relatively non polar compound(s). The methanol extract and residual methanol extract of Sarcolobus globosus stem showed poor wheat rootlet and shoot growth inhibitory activity and no antibacterial activity.

Evaluation of hepatoprotective activity of ethanol extract of Coccinia grandis (L.) Voigt. leaves on experimental rats by acute and chronic models

Kundu, Mintu,Mazumder, Rupa,Kushwaha, M.D. 경희한의학연구센터 2012 Oriental Pharmacy and Experimental Medicine Vol.12 No.2

Coccinia grandis Linn. (Cucurbitaceae) is a climbing perennial branched herb, distributed throughout India. Other plants under the same family have been reported for their hepatoprotective activity. The aim of this work was to study the hepatoprotective effect of crude ethanolic extract from the leaves of C. grandis against liver damage induced by Paracetamol and $CCl_4$ in rats. Administration of Paracetamol (750 mg/kg/day) and $CCl_4$ (3 ml/kg/day) showed a marked increase in SGOT, SGPT, ALP, bilirubin (total, direct), total proteins, globulin, cholesterol and decrease in albumin in comparison with the normal control group. The effect of ethanol extract of C. grandis at 150 mg/kg and 300 mg/kg doses reduced the serum activities caused by Paracetamol and $CCl_4$, which were observed to be statistically significant when compared with that of the control group. The activity exhibited/inhibited by the plant extract was found to be comparable to that of the standard hepatoprotective drug, Silymarin. Silymarin provided a better inhibition or exhibition of the biochemical parameters induced by paracetamol and carbon tetrachloride in rats. The activity may be due to the presence of either alkaloids or triterpenoids or reducing sugars or their combinations, as obtained from the preliminary phytochemical screening of the leaves of the plant. The extract showed no signs of acute toxicity up to a dose level of $3.2gkg^{-1}$ in rats by oral route. Thus, it could be concluded that ethanolic extract of C. grandis leaves possessed significant hepatoprotective activity.

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

Bioactivity of two medicinal plant Xylocarpus granatum Koen. (Meliaceae) and Sarcolobus globosus Wall. (Asclepiadaceae) of Sundarbans mangrove forest

Alamgir, M,Rob, Ma,Kundu, DC,Joy, JHK,Sarder, MM Kyung Hee Oriental Medicine Research Center 2007 Oriental pharmacy and experimental medicine Vol.7 No.4

Two medicinal plant of Sundarbans mangrove forest has been tested for the evaluation of growth inhibitory and antibacterial activity. The methanol extract of Xylocarpus granatum stem bark showed potent wheat rootlet ($IC_{50}=0.01{\mu}g/ml$) and shoot ($IC_{50}=0.23{\mu}g/ml$) growth inhibitory activity in a concentration related manner. The growth inhibitory activity was markedly decreased in residual methanol extract. The methanol extract showed antibacterial activity (MIC > 3 mg/ml) against Bacillus subtilis, Staphylococcus aureous and Proteus vulgaris. The residual methanol extract did not show any antibacterial activity. The results suggest the bioactive principle(s) of Xylocarpus granatum may be relatively non polar compound(s). The methanol extract and residual methanol extract of Sarcolobus globosus stem showed poor wheat rootlet and shoot growth inhibitory activity and no antibacterial activity.