Sustainability Solution : Waste Sponges and Foams for Environmental Remediation

( Vinayak P. Dravid ) 한국물환경학회 2024 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2024 No.-

Enhanced thermoelectric properties of p-type nanostructured PbTe–MTe (M = Cd, Hg) materials

Ahn, Kyunghan,Biswas, Kanishka,He, Jiaqing,Chung, In,Dravid, Vinayak,Kanatzidis, Mercouri G. The Royal Society of Chemistry 2013 Energy & environmental science Vol.6 No.5

<P>We investigated the effect of Cd and Hg substitution on the thermoelectric properties of p-type PbTe–<I>x</I>% CdTe and PbTe–<I>x</I>% HgTe (1 ≤<I>x</I>≤ 5) doped with Na<SUB>2</SUB>Te. Both ingot samples and spark plasma sintered (SPS) samples were studied and the properties are compared. We present detailed structural, spectroscopic and transmission electron microscopy (TEM) data, and transport properties of both cast ingot and SPS samples. The SPS processed samples with HgTe as the second phase show better thermoelectric properties than those with CdTe mainly because of more effective phonon scattering. The SPS process gives significantly lower lattice thermal conductivity for the p-type PbTe–HgTe system than the cast ingot. The same effect is not observed in the p-type PbTe–CdTe system. A maximum <I>ZT</I> of ∼1.64 at ∼770 K is achieved for the p-type PbTe–2% HgTe–1% Na<SUB>2</SUB>Te SPS sample. TEM studies reveal the formation of nanostructures whose number density generally increases with increasing concentrations of CdTe and HgTe as the second phase. Meso-scale grain boundaries along with nanostructured precipitates in the SPS samples play an important role in significantly reducing the lattice thermal conductivity compared to cast ingot in the case of p-type PbTe–HgTe.</P> <P>Graphic Abstract</P><P>We investigated the effect of Cd and Hg substitution on the thermoelectric properties of p-type PbTe–<I>x</I>% CdTe and PbTe–<I>x</I>% HgTe (1 ≤<I>x</I>≤ 5) doped with Na<SUB>2</SUB>Te. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3ee40482j'> </P>

Ligand Conjugation of Chemically Exfoliated MoS₂

Chou, Stanley S.,De, Mrinmoy,Kim, Jaemyung,Byun, Segi,Dykstra, Conner,Yu, Jin,Huang, Jiaxing,Dravid, Vinayak P. American Chemical Society 2013 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.135 No.12

<P>MoS<SUB>2</SUB> is a two-dimensional material that is gaining prominence due to its unique electronic and chemical properties. Here, we demonstrate ligand conjugation of chemically exfoliated MoS<SUB>2</SUB> using thiol chemistry. With this method, we modulate the ζ-potential and colloidal stability of MoS<SUB>2</SUB> sheets through ligand designs, thus enabling its usage as a selective artificial protein receptor for β-galactosidase. The facile thiol functionalization route opens the door for surface modifications of solution processable MoS<SUB>2</SUB> sheets.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2013/jacsat.2013.135.issue-12/ja310929s/production/images/medium/ja-2012-10929s_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja310929s'>ACS Electronic Supporting Info</A></P>

TITANIUM DIOXIDE NANOPARTICLES ASSEMBLED BY DNA MOLECULES HYBRIDIZATION AND LOADING OF DNA INTERACTING PROTEINS

AIGUO WU,TATJANA PAUNESKU,ERIC M. B. BROWN,ANGELA BABBO,CECILLE CRUZ,MOHAMMED ASLAM,VINAYAK DRAVID,GAYLE E. WOLOSCHAK 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2008 NANO Vol.3 No.1

This work demonstrates the assembly of TiO2 nanoparticles with attached DNA oligonucleotides into a 3D mesh structure by allowing base pairing between oligonucleotides. A change of the ratio of DNA oligonucleotide molecules and TiO2 nanoparticles regulates the size of the mesh as characterized by UV-visible light spectra, transmission electron microscopy (TEM) and atomic force microscopy (AFM) images. This type of 3D mesh, based on TiO2-DNA oligonucleotide nanoconjugates, can be used for studies of nanoparticle assemblies in materials science, energy science related to dye-sensitized solar cells, environmental science as well as characterization of DNA interacting proteins in the field of molecular biology. As an example of one such assembly, proliferating cell nuclear antigen protein (PCNA) was cloned, its activity was verified, and the protein was purified, loaded onto double strand DNA oligonucleotide-TiO2 nanoconjugates, and imaged by atomic force microscopy. This type of approach may be used to sample and perhaps quantify and/or extract specific cellular proteins from complex cellular protein mixtures based on their affinity for chosen DNA segments assembled into the 3D matrix.

<i>In Situ</i> Observation of Resistive Switching in an Asymmetric Graphene Oxide Bilayer Structure

Kim, Sungkyu,Jung, Hee Joon,Kim, Jong Chan,Lee, Kyung-Sun,Park, Sung Soo,Dravid, Vinayak P.,He, Kai,Jeong, Hu Young American Chemical Society 2018 ACS NANO Vol.12 No.7

<P>Graphene oxide decorated with oxygen functional groups is a promising candidate as an active layer in resistive switching devices due to its controllable physical-chemical properties, high flexibility, and transparency. However, the origin of conductive channels and their growth dynamics remain a major challenge. We use <I>in situ</I> transmission electron microscopy techniques to demonstrate that nanoscale graphene oxide sheets bonded with oxygen dynamically change their physical and chemical structures upon an applied electric field. Artificially engineered bilayer reduced graphene oxide films with asymmetric oxygen content exhibit nonvolatile write-once-read-many memory behaviors without experiencing the bubble destruction due to the efficient migration of oxygen ions. We clearly observe that a conductive graphitic channel with a conical shape evolves from the upper oxygen-rich region to the lower oxygen-poor region. These findings provide fundamental guidance for understanding the oxygen motions of oxygen-containing carbon materials for future carbon-based nanoelectronics.</P> [FIG OMISSION]</BR>

Negatively Charged Metal Oxide Nanoparticles Interact with the 20S Proteasome and Differentially Modulate Its Biologic Functional Effects

Falaschetti, Christine A.,Paunesku, Tatjana,Kurepa, Jasmina,Nanavati, Dhaval,Chou, Stanley S.,De, Mrinmoy,Song, MinHa,Jang, Jung-tak,Wu, Aiguo,Dravid, Vinayak P.,Cheon, Jinwoo,Smalle, Jan,Woloschak, G American Chemical Society 2013 ACS NANO Vol.7 No.9

<P>The multicatalytic ubiquitin–proteasome system (UPS) carries out proteolysis in a highly orchestrated way and regulates a large number of cellular processes. Deregulation of the UPS in many disorders has been documented. In some cases, such as carcinogenesis, elevated proteasome activity has been implicated in disease development, while the etiology of other diseases, such as neurodegeneration, includes decreased UPS activity. Therefore, agents that alter proteasome activity could suppress as well as enhance a multitude of diseases. Metal oxide nanoparticles, often developed as diagnostic tools, have not previously been tested as modulators of proteasome activity. Here, several types of metal oxide nanoparticles were found to adsorb to the proteasome and show variable preferential binding for particular proteasome subunits with several peptide binding “hotspots” possible. These interactions depend on the size, charge, and concentration of the nanoparticles and affect proteasome activity in a time-dependent manner. Should metal oxide nanoparticles increase proteasome activity in cells, as they do <I>in vitro</I>, unintended effects related to changes in proteasome function can be expected.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-9/nn402416h/production/images/medium/nn-2013-02416h_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn402416h'>ACS Electronic Supporting Info</A></P>

A Semiconducting Organic Radical Cationic Host–Guest Complex

Fahrenbach, Albert C.,Sampath, Srinivasan,Late, Dattatray J.,Barnes, Jonathan C.,Kleinman, Samuel L.,Valley, Nicholas,Hartlieb, Karel J.,Liu, Zhichang,Dravid, Vinayak P.,Schatz, George C.,Van Duyne, R American Chemical Society 2012 ACS NANO Vol.6 No.11

<P>The self-assembly and solid-state semiconducting properties of single crystals of a trisradical tricationic complex composed of the diradical dicationic cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>2(•+)</SUP>) ring and methyl viologen radical cation (MV<SUP>•+</SUP>) are reported. An organic field effect transistor incorporating single crystals of the CBPQT<SUP>2(•+)</SUP>⊂MV<SUP>•+</SUP> complex was constructed using lithographic techniques on a silicon substrate and shown to exhibit <I>p</I>-type semiconductivity with a mobility of 0.05 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>. The morphology of the crystals on the silicon substrate was characterized using scanning electron microscopy which revealed that the complexes self-assemble into “molecular wires” observable by the naked-eye as millimeter long crystalline needles. The nature of the recognition processes driving this self-assembly, radical–radical interactions between bipyridinium radical cations (BIPY<SUP>•+</SUP>), was further investigated by resonance Raman spectroscopy in conjunction with theoretical investigations of the vibrational modes, and was supported by X-ray structural analyses of the complex and its free components in both their radical cationic and dicationic redox states. These spectroscopic investigations demonstrate that the bond order of the BIPY<SUP>•+</SUP> radical cationic units of host and guest components is not changed upon complexation, an observation which relates to its conductivity in the solid-state. We envision the modularity inherent in this kind of host–guest complexation could be harnessed to construct a library of custom-made electronic organic materials tailored to fit the specific needs of a given electronic application.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2012/ancac3.2012.6.issue-11/nn303553z/production/images/medium/nn-2012-03553z_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn303553z'>ACS Electronic Supporting Info</A></P>