Photoautotrophic microalgae Scenedesmus obliquus attached on a cathode as oxygen producers for microbial fuel cell (MFC) operation

Kakarla, R.,Min, B. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.19

Photoautotrophic algae Scenedismus obliquus could attach on the surface of a cathode electrode and produced oxygen for electricity generation in microbial fuel cell (MFC). Oxygen concentration by algae aeration in the cathode chamber increased from 0 to 15.7 mg/l within 12-h, and a voltage generation of 0.47 +/- 0.03 V was obtained with 1000 Ω external resistance. In polarization test, MFC with algal aeration exhibited the maximum power density of 153 mW/m<SUP>2</SUP>, which was 32% higher than the value (116 mW/m<SUP>2</SUP>) with mechanical aeration at oxygen concentration of 5.9 mg/l. The internal resistance of MFC with algal aeration decreased in ohmic resistance (5.9-5.2 Ω) and charge transfer resistance (9.6-7.2 Ω) over 72-h operation. Cyclic voltammetry of cathode during algal aeration revealed higher reduction current of -9.3 mA compared to mechanical aeration (-4.7 mA).

Evaluation of microbial fuel cell operation using algae as an oxygen supplier: carbon paper cathode vs. carbon brush cathode

Kakarla, Ramesh,Min, Booki Springer-Verlag 2014 BIOPROCESS AND BIOSYSTEMS ENGINEERING Vol.37 No.12

IDMMAC: Interference Aware Distributed Multi-Channel MAC Protocol for WSAN

Kakarla, Jagadeesh,Majhi, Banshidhar,Battula, Ramesh Babu Korea Information Processing Society 2017 Journal of information processing systems Vol.13 No.5

In this paper, an interference aware distributed multi-channel MAC (IDMMAC) protocol is proposed for wireless sensor and actor networks (WSANs). The WSAN consists of a huge number of sensors and ample amount of actors. Hence, in the IDMMAC protocol a lightweight channel selection mechanism is proposed to enhance the sensor's lifetime. The IDMMAC protocol divides the beacon interval into two phases (i.e., the ad-hoc traffic indication message (ATIM) window phase and data transmission phase). When a sensor wants to transmit event information to the actor, it negotiates the maximum packet reception ratio (PRR) and the capacity channel in the ATIM window with its 1-hop sensors. The channel negotiation takes place via a control channel. To improve the packet delivery ratio of the IDMMAC protocol, each actor selects a backup cluster head (BCH) from its cluster members. The BCH is elected based on its residual energy and node degree. The BCH selection phase takes place whenever an actor wants to perform actions in the event area or it leaves the cluster to help a neighbor actor. Furthermore, an interference and throughput aware multi-channel MAC protocol is also proposed for actor-actor coordination. An actor selects a minimum interference and maximum throughput channel among the available channels to communicate with the destination actor. The performance of the proposed IDMMAC protocol is analyzed using standard network parameters, such as packet delivery ratio, end-to-end delay, and energy dissipation, in the network. The obtained simulation results indicate that the IDMMAC protocol performs well compared to the existing MAC protocols.

Novel electrically conductive and ferromagnetic composites of poly(aniline-co-aminonaphthalenesulfonic acid) with iron oxide nanoparticles: Synthesis and characterization

Reddy, Kakarla Raghava,Lee, Kwang-Pill,Gopalan, Anantha Iyengar Wiley 2007 Journal of Applied Polymer Science Vol.106 No.2

<P>Nanocomposites of iron oxide (Fe<SUB>3</SUB>O<SUB>4</SUB>) with a sulfonated polyaniline, poly(aniline-co-aminonaphthalenesulfonic acid) [SPAN(ANSA)], were synthesized through chemical oxidative copolymerization of aniline and 5-amino-2-naphthalenesulfonic acid/1-amino-5-naphthalenesulfonic acid in the presence of Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles. The nanocomposites [Fe<SUB>3</SUB>O<SUB>4</SUB>/SPAN(ANSA)-NCs] were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, UV–visible spectroscopy, thermogravimetric analysis (TGA), superconductor quantum interference device (SQUID), and electrical conductivity measurements. The TEM images reveal that nanocrystalline Fe<SUB>3</SUB>O<SUB>4</SUB> particles were homogeneously incorporated within the polymer matrix with the sizes in the range of 10–15 nm. XRD pattern reveals that pure Fe<SUB>3</SUB>O<SUB>4</SUB> particles are having spinel structure, and nanocomposites are more crystalline in comparison to pristine polymers. Differential thermogravimetric (DTG) curves obtained through TGA informs that polymer chains in the composites have better thermal stability than that of the pristine copolymers. FTIR spectra provide information on the structure of the composites. The conductivity of the nanocomposites (∼ 0.5 S cm<SUP>−1</SUP>) is higher than that of pristine PANI (∼ 10<SUP>−3</SUP> S cm<SUP>−1</SUP>). The charge transport behavior of the composites is explained through temperature difference of conductivity. The temperature dependence of conductivity fits with the quasi-1D variable range hopping (quasi-1D VRH) model. SQUID analysis reveals that the composites show ferromagnetic behavior at room temperature. The maximum saturation magnetization of the composite is 9.7 emu g<SUP>−1</SUP>. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007</P>

Application of high-salinity stress for enhancing the lipid productivity of Chlorella sorokiniana HS1 in a two-phase process

Ramesh Kakarla,최정운,윤진호,김병혁,허진아,이수진,조대현,Rishiram Ramanan,김희식 한국미생물학회 2018 The journal of microbiology Vol.56 No.1

Increased lipid accumulation of algal cells as a response to environmental stress factors attracted much attention of researchers to incorporate this stress response into industrial algal cultivation process with the aim of enhancing algal lipid productivity. This study applies high-salinity stress condition to a two-phase process in which microalgal cells are initially grown in freshwater medium until late exponential phase and subsequently subjected to high-salinity condition that induces excessive lipid accumulation. Our initial experiment revealed that the concentrated culture of Chlorella sorokiniana HS1 exhibited the intense fluorescence of Nile red at the NaCl concentration of 60 g/L along with 1 g/L of supplemental bicarbonate after 48 h of induction period without significantly compromising cultural integrity. These conditions were further verified with the algal culture grown for 7 days in a 1 L bottle reactor that reached late exponential phase; a 12% increment in the lipid content of harvested biomass was observed upon inducing high lipid accumulation in the concentrated algal culture at the density of 5.0 g DW/L. Although an increase in the sum of carbohydrate and lipid contents of harvested biomass indicated that the external carbon source supplemented during the induction period increased overall carbon assimilation, a decrease in carbohydrate content suggested the potential reallocation of cellular carbon that promoted lipid droplet formation under high-salinity stress. These results thus emphasize that the two-phase process can be successfully implemented to enhance algal lipid productivity by incorporating high-salinity stress conditions into the pre-concentrated sedimentation ponds of industrial algal production system.

IDMMAC: Interference aware Distributed Multi-channel MAC protocol for WSAN

Jagadeesh Kakarla,Banshidhar Majhi,Ramesh Babu Battula 한국정보처리학회 2017 Journal of information processing systems Vol.13 No.5

In this paper, an interference aware distributed multi-channel MAC (IDMMAC) protocol is proposed forwireless sensor and actor networks (WSANs). The WSAN consists of a huge number of sensors and ampleamount of actors. Hence, in the IDMMAC protocol a lightweight channel selection mechanism is proposed toenhance the sensor's lifetime. The IDMMAC protocol divides the beacon interval into two phases (i.e., the adhoctraffic indication message (ATIM) window phase and data transmission phase). When a sensor wants totransmit event information to the actor, it negotiates the maximum packet reception ratio (PRR) and thecapacity channel in the ATIM window with its 1-hop sensors. The channel negotiation takes place via acontrol channel. To improve the packet delivery ratio of the IDMMAC protocol, each actor selects a backupcluster head (BCH) from its cluster members. The BCH is elected based on its residual energy and nodedegree. The BCH selection phase takes place whenever an actor wants to perform actions in the event area orit leaves the cluster to help a neighbor actor. Furthermore, an interference and throughput aware multichannelMAC protocol is also proposed for actor-actor coordination. An actor selects a minimuminterference and maximum throughput channel among the available channels to communicate with thedestination actor. The performance of the proposed IDMMAC protocol is analyzed using standard networkparameters, such as packet delivery ratio, end-to-end delay, and energy dissipation, in the network. Theobtained simulation results indicate that the IDMMAC protocol performs well compared to the existing MACprotocols.

Synthesis of MWCNTs-core/thiophene polymer-sheath composite nanocables by a cationic surfactant-assisted chemical oxidative polymerization and their structural properties

Reddy, Kakarla Raghava,Jeong, Han Mo,Lee, Youngil,Raghu, Anjanapura Venkataramanaiah Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of polymer science Part A, Polymer chemist Vol.48 No.7

<P>Multi-walled carbon nanotubes (MWCNTs)-core/thiophene polymer-sheath composite nanocables were synthesized by chemical oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) with oxidant (FeCl<SUB>3</SUB>) in the presence of cationic surfactant, deceyltrimethyl ammonium bromide (DTAB). In the polymerization process, DTAB surfactant molecules were adsorbed on the surface of MWCNTs and forms MWCNTs-DTAB soft template. Upon the addition of EDOT and oxidant, the polymerization take place on the surface of MWCNTs and PEDOT is gradually deposited on the surface of MWCNTs. The resulting MWCNTs-PEDOT nanocomposites have the nanocable structure. Nanocomposites were characterized by HRTEM, FE-SEM, XRD, XPS, TGA, FTIR and PL, respectively. The π-π interactions between PEDOT and MWCNTs enhancing the thermal and electrical properties of the nanocomposites with loading of MWCNTs. The temperature dependence conductivity measurements show that the conductivity of the nanocomposite decrease with a decrease of temperature, and conductivity-temperature relationship is well fit by the quasi-one dimensional variable range hopping mode. The mechanism for the formation of composite nanocables was explained on the basis of self- assembly of micelles. The reported self-assembly strategy for the synthesis of PEDOT-coated MWCNTs in micellar medium is a rapid, versatile, potentially scalable, stable, and making it useful for further exploitation in a varies types of applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1477–1484, 2010</P> <B>Graphic Abstract</B> <P>The MWCNTs-thiophene polymer core-sheath composite nanocables were synthesized by chemical oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) with oxidant (FeCl<SUB>3</SUB>) in the presence of cationic surfactant, deceyltrimethyl ammonium bromide (DTAB) that acts as the structure-directing agen. In the polymerization process, DTAB surfactant molecules were adsorbed on the surface of MWCNTs and forms MWCNTs-DTAB soft template. On the addition of EDOT and oxidant, the polymerization takes place on the surface of MWCNTs, and PEDOT is gradually deposited on the surface of MWCNTs. The resulting nanocomposites have the nanocable structure as shown in the scheme. The structural, morphological, thermal, optical, and electrical properties of the synthesized nanocomposites were fully characterized by using various techniques. The mechanism for the formation of composite nanocables was explained on the basis of self-assembly of micelles. The reported self-assembly strategy for the synthesis of PEDOT-coated MWCNTs in micellar medium is a rapid, versatile, potentially scalable, stable, and making it useful for further exploitation in various types of applications. <img src='wiley_img_2010/0887624X-2010-48-7-POLA23883-gra001.gif' alt='wiley_img_2010/0887624X-2010-48-7-POLA23883-gra001'> </P>

Synthesis and characterization of novel conducting composites of Fe₃O₄ nanoparticles and sulfonated polyanilines

Reddy, Kakarla Raghava,Lee, Kwang-Pill,Iyengar, Anantha Gopalan Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.104 No.6

<P>Surface charged iron oxide (Fe<SUB>3</SUB>O<SUB>4</SUB>) nanoparticles were used for the synthesis of sulfonated polyaniline (SPAN)-Fe<SUB>3</SUB>O<SUB>4</SUB> nanocomposites (SPAN/Fe<SUB>3</SUB>O<SUB>4</SUB>-NCs). 2,5-diaminobenzenesulfonic acid (DABSA) and 2-aminobenzenesulfonic acid (ABSA) were independently polymerized with aniline to form SPAN. The structure of the composites was characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, conductivity and magnetic properties. TEM reveals that Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles are “glued” with SPAN in the composite. TGA indicates that SPAN/Fe<SUB>3</SUB>O<SUB>4</SUB>-NCs are having better thermal stability. The room temperature conductivity of SPAN/Fe<SUB>3</SUB>O<SUB>4</SUB>-NCs is higher than that of pristine PANI and SPAN. SPAN/Fe<SUB>3</SUB>O<SUB>4</SUB>-NCs exhibits magnetic behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4127–4134, 2007</P>

Synthesis and properties of magnetite/poly (aniline-co-8-amino-2-naphthalenesulfonic acid) (SPAN) nanocomposites

Reddy, Kakarla Raghava,Lee, Kwang-Pill,Gopalan, Anantha Iyengar,Showkat, Ali Md JOHN WILEY & SONS LTD 2007 POLYMERS FOR ADVANCED TECHNOLOGIES Vol.18 No.1

<P>Composites were prepared by incorporating magnetite (Fe<SUB>3</SUB>O<SUB>4</SUB>) nanoparticles into the matrix of a sulfonated polyaniline (SPAN) [poly(aniline-co-8-amino-2-naphthalenesulfonic acid) PANSA] through chemical oxidative polymerization of a mixture of aniline and 8-amino-2-naphthalenesulfonic acid in the presence of magnetite nanoparticles. The composite, magnetite/SPAN(PANSA) was characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), elemental analysis (EA), Fourier transform infrared (FT-IR) spectra, UV-vis spectroscopy, thermogravimetric analysis (TGA), conductivity and magnetic properties measurements. TEM image shows that magnetite nanoparticles were finely distributed into the SPAN matrix. XRD pattern of the nanocomposite reveals the presence of additional crystalline order through the appearance of a sharp peak at ∼43° and 71°. Conductivity of the nanocomposite (0.23 S/cm) is much higher than pristine copolymer (1.97 × 10<SUP>−2</SUP> S/cm). The results of FT-IR and UV-visible spectroscopy reveal the presence of molecular level interactions between SO<EM><SUB>3</SUB><SUP>−</SUP></EM> groups in SPAN and magnetite nanoparticles in the composite. Copyright © 2006 John Wiley & Sons, Ltd.</P>

Synthesis of metal (Fe or Pd)/alloy (Fe–Pd)-nanoparticles-embedded multiwall carbon nanotube/sulfonated polyaniline composites by γ irradiation

Reddy, Kakarla Raghava,Lee, Kwang-Pill,Gopalan, Anantha Iyengar,Kim, Min Seok,Showkat, Ali Md,Nho, Young Chang Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of polymer science Part A, Polymer chemist Vol.44 No.10

<P>Composites of multiwall carbon nanotubes (MWCNTs) and sulfonated polyaniline (SPAN) were prepared through the oxidative polymerization of a mixture of aniline, 2,5-diaminobenzene sulfonic acid, and MWCNTs. Fe, Pd, or Fe–Pd alloy nanoparticles were embedded into the MWCNT–SPAN matrix by the reduction of Fe, Pd, or a mixture of Fe and Pd ions with γ radiation. Sulfonic acid groups and the emeraldine form of backbone units in SPAN served as the source for the reduction of the metal ions in the presence of γ radiation. The existence of metallic/alloy particles in the MWCNT–SPAN matrix was further ascertained through characterization by high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, and conductivity measurements. HRTEM pictures clearly revealed the existence of Fe, Pd, and Fe–Pd nanoparticles of various sizes in the MWCNT–SPAN matrices. There were changes in the electronic properties of the MWCNT–SPAN–M composites due to the interaction between the metal nanoparticles and MWCNT–SPAN. Metal-nanoparticle-loaded MWCNT–SPAN composites (MWCNT–SPAN–M; M = Fe, Pd, or Fe–Pd alloy) showed better thermal stability than the pristine polymers. The conductivity of the MWCNT–SPAN–M composites was approximately 1.5 S cm<SUP>−1</SUP>, which was much higher than that of SPAN (2.46 × 10<SUP>−4</SUP> S cm<SUP>−1</SUP>). Metal/alloy-nanoparticle-embedded, MWCNT-based composite materials are expected to find applications in molecular electronics and other fields. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3355–3364, 2006</P> <B>Graphic Abstract</B> <P>Composites of multiwall carbon nanotubes (MWCNTs) and sulfonated polyaniline (SPAN) loaded with metal (M = Fe, Pd, or Fe–Pd alloy) nanoparticles were synthesized by γ irradiation. The synthesis consisted of two steps: the preparation of the composite of SPAN with MWCNTs and the loading of the metal nanoparticles into the MWCNT–SPAN composite matrix via the reduction of higher valence metal ions by γ irradiation. The MWCNT–SPAN–M nanocomposites exhibited improved thermal stability and conductivity over pristine SPAN. The presence of metal/alloy nanoparticles induced quantum size effects in the electronic properties of the composites. <img src='wiley_img/0887624X-2006-44-10-POLA21451-gra001.gif' alt='wiley_img/0887624X-2006-44-10-POLA21451-gra001'> </P>