Surface Enhanced Raman Spectroscopy on Silver-Nanoparticle-Coated Carbon-Nanotube Networks Fabricated by Electrophoretic Deposition

Anirban Sarkar,Hao Wang,Theda Daniels-Race 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2

In this study, the efficiency of silver nanoparticle (AgNP) decorated carbon nanotube (CNT) based porous substrates has been investigated for surface-enhanced Raman spectroscopy (SERS) applications. The fabrication of uniform thin coatings of carbon nanotubes is accomplished by Electrophoretic Deposition (EPD) on organosilane functionalized silicon substrates. The deposition process exemplifies a fast, reproducible and singlestep room temperature coating strategy to fabricate horizontally aligned porous CNT network. Surfactant stabilized AgNPs were deposited on the CNT networks by immersion coating. The acquired Raman spectra of Rhodamine6G (R6G) analyte examined on the fabricated Ag-CNT-Si substrates exhibited enhanced signal intensity values when compared to SERS-active planar AgNP-Si substrates. An overall enhancement factor of ~109 was achieved for the tested analyte which enables pushing the limit of detection to 1 × 10−12 M (1 pM). The enhancement can be attributed to the large surface area offered by the AgNP-CNT porous network, which is expected to increase the number of effective “hot spots” for the SERS effect.

A simple template-free bioinspired route of 1D Bi2S3 nanorods synthesis for electrochemical CO2 reduction to formate

Anirban Chowdhury,Chandra Bhan,Nageswara Rao Peela,Animes Kumar Golder 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

This work demonstrates a simple bioinspired route of synthesizing template-free 1D Bi2S3 nanorods,Bi2S3-NRs(bio), using Sechium edule fruit. The morphology of nanorods was controlled via capping ofascorbic acid (AA), a major bio-analyte. The average length and diameter were reduced from 485 to229.5 nm and 123 to 31 nm, respectively, compared with Bi2S3-NRs(control), Bi2S3 nanorods synthesizedin the absence of bio-extract/reducing agent. The XPS analysis confirmed that the formation of Bi2O3 inBi2S3-NRs(control), could be prevented in Bi2S3-NRs(bio) because of AA capping. A plausible mechanisticroute of synthesis of Bi2S3-NRs(bio) is also proposed herein. The modified Bi2S3-NRs(bio)/Toray carbonpaper (TCP) electrode exhibited selective HCOO– formation with FE of 92.3% against 50.9% for theBi2S3-NRs(control)/TCP electrode at 1.5 V (vs. Ag/AgCl). Higher FE exhibited by Bi2S3-NRs(bio) catalysthas resulted from its compositional and morphological attributes. In-situ electrochemical oxidation ofBi2S3-NRs(bio) to Bi2O2CO3 also could act as active sites for enhanced and selective HCOO– formation.

Review of Technology Used to Improve Heat and Mass Transfer Characteristics of Adsorption Refrigeration System

Anirban Sur,Randip K. Das 대한설비공학회 2016 International Journal of Air-Conditioning and Refr Vol.24 No.2

Researchers proved that, heat powered adsorption refrigeration technology is very effective methods for reutilization of low-grade thermal energy such as industrial waste heat, solar energy, and exhaust gases from engines. But to make it commercially competitive with the well-known vapor compression and absorption refrigeration system, the processes require high rates of heat and mass transfer characteristic between adsorbate and adsorbent as well as externally supplied heat exchanging fluid. This paper reviews various techniques that have been developed and applied to enhance the heat transfer and mass transfer in adsorber beds, and also discuss their effects of the performance on adsorption system. A comprehensive literature review has been conducted and it was concluded that this technology, although attractive, has limitations regarding its heat and mass transfer performance that seem difficult to overcome. Therefore, more researches are required to improve heat and mass transfer performance and sustainability of basic adsorption cycles.

Development of prediction model through linear multiple regression for the prediction of longitudinal stiffness of embroidered fabric

Anirban Dutta,Biswapati Chatterjee 한국의류학회 2020 Fashion and Textiles Vol.7 No.1

Embroidery through computer aided semi-automatic machines is one of the most widely used option for the surface ornamentation of apparel fabrics at present. Since the embroidery process includes addition of certain amount of embroidery-threads depending upon the design motif, it is quite obvious that basic physical and functional properties of fabric are subject to change. It is therefore important to develop an algorithm or empirical equation for proper prediction of the properties of the embroidered fabric, relevant to its required end-use in apparel industry. In this context, an effort has been made to determine a prediction equation through linear multiple regressions for the prediction of longitudinal stiffness of embroidered fabric in terms of flexural rigidity in warp direction of the base fabric, considering the input parameters as warp-way flexural rigidity of the base fabric, breaking load and linear density of the embroidery thread, stitch density, average stitch length and average stitch angle of the embroidery design. The final Prediction model is statistically verified taking new embroidery samples of different varieties. It is found that the model can predict with a very satisfactory level of accuracy. Also, the influences of the embroidery parameters in this context have been analyzed through the corresponding regression coefficients and the three dimensional (3D) surface curves. Stitch density has been emerged as the most influential parameter, followed by the stitch length and the stitch angle.

Electro-Optical Characterization of Cyanine-Based GUMBOS and nanoGUMBOS

Anirban Sarkar,Kalyan Kanakamedala,Naveen N. Jagadish,Atiya Jordan,Susmita Das,Noureen Siraj,Isiah M. Warner,Theda Daniels-Race 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5

Over the last decade in materials science, molecular electronics has emerged as one of the most rapidly developing interdisciplinary research areas with the prospects of ultimate miniaturization and integration of functional organic species with traditional silicon based semiconductor technology. To this end, fundamental studies to investigate the electrical and optical properties of organic nanomaterials deserve special attention. In this work, conductive probe atomic force microscopy (CP-AFM) and Raman spectroscopy have been performed on a new class of ionic materials, referred to as group of uniform materials based on organic salts (GUMBOS) and nanoparticles derived from these GUMBOS, termed as nanoGUMBOS. The GUMBOS investigated in this study are 1,1'-Diethyl-2,2'-cyanine bis (trifluoromethanesulfonyl) imide ([PIC][NTf2]) and 1,1'-Diethyl-2,2'-cyanine bis (pentafluoromethanesulfonyl) imide ([PIC][BETI]), which have been synthesized by use of a facile, template free anion exchange reaction between their respective parent compounds, followed by an ultrasonication assisted, additive free re-precipitation reaction to obtain the nanoscale particles (nanoGUMBOS). The ([PIC][NTf2] nanoGUMBOS were found to self-assemble into distinct diamond-like, trapezoid structures whereas [PIC][BETI] exhibited rod-like structures. [PIC][NTf2] nanoGUMBOS induced ~25 and ~38 times enhancement in the Raman signal intensity as compared to the parent compound [PIC][I] and [PIC][BETI] nano- GUMBOS respectively. In conjunction with the results of Raman spectra, the current-voltage (I-V) data obtained by CP-AFM are also presented as first-time evidence of electrical performance exhibited by these unique class of materials. The results reported in this study are indicative of their potential incorporation into next generation organic thin film applications in optoelectronics, dye-sensitized solar cells, and chemical sensors.

Surface characterization and material migration during surface modification of die steels with silicon, graphite and tungsten powder in EDM process

Anirban Bhattacharya,Ajay Batish,Naveen Kumar 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.1

The present study reports the results of an experimental work carried out to evaluate the improvement in machined surface properties of die steels machined using powder mixed electric discharge machining (PMEDM) process. Two surface responses, surface finish and microhardness were analyzed for changes when machined with Si, W and graphite powders mixed in dielectric fluid. The machined surfaces were subsequently analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) to study the element migration from powder, dielectric and the tool. The powder mixed with dielectric and its concentration, current and pulse on time were identified as the significant factors affecting surface finish. Brass electrode and tungsten powder resulted in good surface finish. Amongst the dielectrics used, kerosene provided a better cooling effect whereas EDM oil resulted in better surface finish. The microhardness of the machined surface was also affected by powder and its concentration, current, pulse on time and electrode material. W-Cu electrode and W powder resulted in a higher microhardness. The SEM and EDS analysis showed significant migration of material from the suspended powder, electrode and dielectric to the machined surface.

Rent setting mechanism and housing affordability

Anirban Mostafa,Francis K. W. Wong,Eddie C.M. Hui 한국주거학회 2007 한국주거학회 국제학술대회논문집 Vol.2007 No.8

Numerical Modeling and Thermal Analysis of an Adsorption Refrigeration System

Anirban Sur,Randip K. Das 대한설비공학회 2015 International Journal of Air-Conditioning and Refr Vol.23 No.4

The aim of this paper is to develop a complete, precise and simple numerical model based on the thermophysical properties of an adsorptive cooling system (using activated carbon–methanol pair), analyze and discuss the heat and mass transfer processes and identify the parameters which influence the system performance. In the design of adsorption refrigeration system, the characteristics of both adsorbate–adsorbent pairs and system operating conditions are very important. So in this model, different thermophysical properties of working pair such as, specific heat, density, isosteric heat of adsorption and desorption, and different temperatures of the system are considered. A simulation code, written in FORTRAN, is carried out. The performance of the system is assessed in terms of refrigeration effect and coeficient of performance (COP).

Attomolar Level Detection of Raman Molecules with Hierarchical Silver Nanostructures Including Tiny Nanoparticles between Nanosized Gaps Generated in Silver Petals

Dandapat, Anirban,Lee, Tae Kyung,Zhang, Yiming,Kwak, Sang Kyu,Cho, Eun Chul,Kim, Dong-Hwan American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.27

<P>We developed a route for synthesizing Ag nanostructures with tunable morphologies for ultrasensitive surface-enhanced Raman spectroscopy. Through the consecutive addition of three reducing agents (i.e., 4-mercaptobenzoic acid, trisodium citrate, and ascorbic acid) to an aqueous solution of silver nitrate, hierarchical flower-like Ag nanostructures were produced. The nanostructures had Ag petals in which nanosized gaps were generated, and small Ag nanoparticles were incorporated within the gaps. Theoretically, the nanostructures exhibited highly enhanced electric fields in the outer-shell regions where the small Ag nanoparticles were densely located. Combining the enhanced field effect with resonance effect of a Raman-active molecule (methylene blue) at a specific wavelength, measurable Raman signals were obtained at concentrations as low as 100 attomolar (10<SUP>–16</SUP> M; corresponding to 10<SUP>–21</SUP> mol). Key factors were discussed for the synthesis of the Ag nanostructures while finely controlling the morphologies of hierarchical Ag nanostructures, thereby modulating the intensity of surface-enhanced resonance Raman spectroscopy (SERRS) signals. Therefore, this synthetic method produces highly promising nanostructures for SERRS-based applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-27/acsami.5b03109/production/images/medium/am-2015-03109d_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b03109'>ACS Electronic Supporting Info</A></P>

Evaluation of Milk Trace Elements, Lactate Dehydrogenase, Alkaline Phosphatase and Aspartate Aminotransferase Activity of Subclinical Mastitis as and Indicator of Subclinical Mastitis in Riverine Buffalo (Bubalus bubalis)

Guha, Anirban,Gera, Sandeep,Sharma, Anshu Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.3

Mastitis is a highly morbid disease that requires detection at the subclinical stage. Tropical countries like India mainly depend on milch buffaloes for milk. The present study was conducted to investigate whether the trace minerals viz. copper (Cu), iron (Fe), zinc (Zn), cobalt (Co) and manganese (Mn) and enzyme activity of lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and aspartate aminotransferase (AST) in riverine buffalo milk can be used as an indicator of subclinical mastitis (SCM) with the aim of developing suitable diagnostic kit for SCM. Trace elements and enzyme activity in milk were estimated with Atomic absorption Spectrophotometer, GBC 932 plus and biochemical methods, respectively. Somatic cell count (SCC) was done microscopically. The cultural examination revealed Gram positive bacteria as the most prevalent etiological agent. A statistically significant (p<0.01) increase in SCC, Fe, Zn, Co and LDH occurred in SCM milk containing gram positive bacterial agents only. ALP was found to be elevated in milk infected by both gram positive and negative bacteria. The percent sensitivity, specificity and accuracy, predictive values and likelihood ratios were calculated taking bacterial culture examination and $SCC\geq2{\times}10^5$ cells/ml of milk as the benchmark. Only ALP and Zn, the former being superior, were found to be suitable for diagnosis of SCM irrespective of etiological agents. LDH, Co and Fe can be introduced in the screening programs where Gram positive bacteria are omnipresent. It is recommended that both ALP and Zn be measured together in milk to diagnose buffalo SCM, irrespective of etiology.