A Continuous Flow Device for the Purification of Semiconducting Nanoparticles by AC Dielectrophoresis

2014 ◽  
Vol 1700 ◽  
pp. 85-90
Author(s):  
Rustin Golnabi ◽  
Su (Ike) Chih Chi ◽  
Stephen L. Farias ◽  
Robert C. Cammarata
Keyword(s):  
Continuous Flow ◽  
Building Blocks ◽  
Dielectric Constants ◽  
Dielectrophoretic Force ◽  
Structural Variations ◽  
Semiconducting Nanoparticles ◽  
Random Mixture ◽  
Production Techniques ◽  
Semiconducting Nanotubes ◽  
Walled Carbon Nanotubes

ABSTRACTSingle-walled carbon nanotubes (SWCNTs) have attracted significant attention as building blocks for future nanoscale electronics due to their small size and unique electronic properties. However, current SWCNT production techniques generate a mixture of two types of nanotubes with divergent electrical behaviors due to structural variations. Some of the nanotubes act as metallic materials while others display semiconducting properties. This random mixture has prevented the realization of functional carbon nanotube-based nanoelectronics. Here, a method of purifying a continuous flow of semiconducting nanotubes from an initially random mixture of both metallic and semiconducting SWCNTs in suspension is presented. This purification uses A/C dielectrophoresis (DEP), and takes advantage of the large difference of the relative dielectric constants between metallic and semiconducting SWCNTs. Because of a difference in magnitude and opposite directions of a dielectrophoretic force imposed on the random SWCNT solution, metallic SWCNTs deposit onto an electrode while semiconducting SWCNTs remain in suspension [3]. A discussion of these techniques is presented, along with a dielectrophoretic force-utilized microfluidic lab-on-a-chip device that can accomplish purification of semiconducting nanoparticles at high processing rates. The effectiveness of the device is characterized using Raman spectroscopy analysis on separated samples.

scholarly journals Structural and Chemical Hierarchy in Hydroxyapatite Coatings

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4447
Author(s):  
Karlis A. Gross ◽  
Christiane Petzold ◽  
Liene Pluduma-LaFarge ◽  
Maris Kumermanis ◽  
Håvard J. Haugen
Keyword(s):  
Electrical Potential ◽  
Building Blocks ◽  
X Ray Diffraction ◽  
Kelvin Probe ◽  
Structural Variations ◽  
Homogeneous Microstructure ◽  
Structural Hierarchy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hydroxyapatite Coatings

Hydroxyapatite coatings need similarly shaped splats as building blocks and then a homogeneous microstructure to unravel the structural and chemical hierarchy for more refined improvements to implant surfaces. Coatings were thermally sprayed with differently sized powders (20–40, 40–63 and 63–80 µm) to produce flattened homogeneous splats. The surface was characterized for splat shape by profilometry and Atomic force microscopy (AFM), crystal size by AFM, crystal orientation by X-ray diffraction (XRD) and structural variations by XRD. Chemical composition was assessed by phase analysis, but variations in chemistry were detected by XRD and Raman spectroscopy. The resulting surface electrical potential was measured by Kelvin probe AFM. Five levels of structural hierarchy were suggested: the coating, the splat, oriented crystals, alternate layers of oxyapatite and hydroxyapatite (HAp) and the suggested anion orientation. Chemical hierarchy was present over a lower range of order for smaller splats. Coatings made from smaller splats exhibited a greater electrical potential, inferred to arise from oxyapatite, and supplemented by ordered OH− ions in a rehydroxylated surface layer. A model has been proposed to show the influence of structural hierarchy on the electrical surface potential. Structural hierarchy is proposed as a means to further refine the properties of implant surfaces.

A Model of The Metal-Ferroelectric-Metal Capacitor

1993 ◽  
Vol 310 ◽  
Author(s):  
G. Teowee ◽  
D.R. Uhlmann
Keyword(s):  
Physical Vapor Deposition ◽  
Building Blocks ◽  
Dielectric Constants ◽  
Exponential Dependence ◽  
Leakage Currents ◽  
Metal Structures ◽  
Low Dielectric ◽  
Model Predictions ◽  
Pzt Films ◽  
Wet Chemical

AbstractFerroelectric (FE) films, especially PZT films, have received increasing attention for microelectronic applications such as ferroelectric memory and high density DRAM. There has been significant progress in the preparation of high quality PZT films involving wet chemical and physical vapor deposition techniques. Metal-FE-metal structures, typified by Pt-PZT-Pt capacitors, are the basic building blocks for the ferroelectric devices. The leakage currents of the capacitors are known to be non-ohmic and exhibit an exponential dependence on applied voltage.The present paper presents a model based on totally depleted back-to-back Shottky barriers. Predictions based on the model can provide significant new understanding of the FE behavior of thin films. For example, the assumption of total depletion leads to the presence of a built-in field within the film which can explain the ubiquitously higher values of coercive field in FE films than found in bulk ceramics. It will be shown that the agreement between model predictions and actual device I-V characteristics of Pt-PZT-Pt capacitors is very close. Further, the model can also explain the observed hysteresis loop asymmetry and low dielectric constants of films of relaxor FE's, whose dielectric constants are much smaller than those of bulk materials.

Continuous Dielectrophoretic Separation of Multiple Particles in a Microfluidic Chip

2008 ◽  
Author(s):  
Christian Davidson ◽  
Junjie Zhu ◽  
Xiangchun Xuan
Keyword(s):  
Particle Size ◽  
Electric Field ◽  
Flow Separation ◽  
Microfluidic Chip ◽  
Continuous Flow ◽  
Uniform Electric Field ◽  
Dielectrophoretic Force ◽  
Size Dependent ◽  
Multiple Particles ◽  
Dc Dielectrophoresis

We successfully demonstrate that DC dielectrophoresis can be utilized to separate particles of three dissimilar sizes simultaneously in a microfluidic chip. This continuous-flow separation is attributed to the particle size dependent dielectrophoretic force that is generated by the non-uniform electric field around a single insulating hurdle on the channel sidewall.

Synthesis of photolabile protecting group (PPG) protected uronic acid building blocks: applications in carbohydrate synthesis with the assistance of a continuous flow photoreactor

2019 ◽  
Vol 6 (23) ◽  
pp. 3859-3863 ◽  
Author(s):  
Varsha Tiwari ◽  
Adesh Kumar Singh ◽  
Priyanka Chaudhary ◽  
Peter H. Seeberger ◽  
Jeyakumar Kandasamy
Keyword(s):  
Continuous Flow ◽  
Uronic Acid ◽  
Building Blocks ◽  
Protecting Group ◽  
Carbohydrate Synthesis ◽  
Photolabile Protecting Group

Photolabile groups protected uronic acid building blocks were synthesized and used for carbohydrate synthesis with the help of a continuous flow photo-reactor.

Carbon Nanotube Based Molecular Electronic Devices

1998 ◽  
Vol 13 (9) ◽  
pp. 2357-2362 ◽  
Author(s):  
Madhu Menon ◽  
Deepak Srivastava
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Electronic Devices ◽  
Tight Binding ◽  
Single Walled Carbon Nanotubes ◽  
Building Blocks ◽  
Local Minima ◽  
Molecular Electronic ◽  
Walled Carbon Nanotubes

Complex three-point junctions of single-walled carbon nanotubes are proposed as building blocks of nanoscale electronic devices. Both T- and Y-junctions, made up of tubes with differing diameters and chiralities, are studied as prototypes. All the proposed complex junctions have been found to be local minima of the total energy on relaxation with a generalized tight-binding molecular dynamics scheme.

ChemInform Abstract: Continuous Flow Synthesis of α-Halo Ketones: Essential Building Blocks of Antiretroviral Agents.

ChemInform ◽  
2014 ◽  
Vol 45 (30) ◽  
pp. no-no
Author(s):  
Vagner D. Pinho ◽  
Bernhard Gutmann ◽  
Leandro S. M. Miranda ◽  
Rodrigo O. M. A. de Souza ◽  
C. Oliver Kappe
Keyword(s):  
Continuous Flow ◽  
Building Blocks ◽  
Flow Synthesis ◽  
Antiretroviral Agents

MOLECULAR ACIDITY OF BUILDING BLOCKS OF BIOLOGICAL SYSTEMS: A DENSITY FUNCTIONAL REACTIVITY THEORY STUDY

2013 ◽  
Vol 12 (05) ◽  
pp. 1350034 ◽  
Author(s):  
DONGBO ZHAO ◽  
CHUNYING RONG ◽  
DULIN YIN ◽  
SHUBIN LIU
Keyword(s):  
Amino Acids ◽  
Correlation Coefficient ◽  
Density Functional ◽  
Atomic Orbital ◽  
Biological Systems ◽  
Building Blocks ◽  
Dielectric Constants ◽  
Molecular Systems ◽  
Biologically Relevant ◽  
Linear Relationships

An accurate prediction of the molecular acidity by employing ab initio or density functional approaches for typical molecular systems is still challenging. Recently, we proposed to utilize two quantum descriptors, molecular electrostatic potential (MEP) and the sum of valence natural atomic orbital (NAO) energies on the nucleus of both the acidic atom and leaving proton, to quantitatively evaluate the pKa values. This new approach has been validated by a number of organic and inorganic systems and justified within the framework of density functional reactivity theory (DFRT). In this work, we apply the approach to building blocks of biological systems, namely, 20 natural α-amino acids and 5 DNA/RNA bases, together with a few other biologically relevant species. Our results show that there exists a strong linear correlation between MEP on the nucleus of the N atom and the sum of N 2p NAO energies, with the correlation coefficient R2 = 0.99. Also, we observe that both MEP on the nitrogen nucleus and the sum of N 2p NAO energies correlate well with experimental pKa values, with the correlation coefficient equal to 0.91. Using this established model, we predicted the trend of pKa changes of amino acids in proteins with different dielectric constants. We also applied the model to predict pKa values for dipeptides. Implications of these linear relationships to understand functions and reactivity of biological systems are discussed as well.

Acylchloride-Functionalized Multiple-Walled Carbon Nanotubes Reinforced Polyimide for High Dielectric Properties

2011 ◽  
Vol 239-242 ◽  
pp. 2655-2658
Author(s):  
Heng Feng Li ◽  
Guo Wen He ◽  
Jun Li ◽  
Jun Chen ◽  
Jiang Cong Chen
Keyword(s):  
Carbon Nanotubes ◽  
Composite Films ◽  
Dielectric Constants ◽  
Acid Mixture ◽  
Mass Fractions ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Polyimide Matrix ◽  
High Dielectric ◽  
Walled Carbon Nanotubes

A series of polyimide composites with various mass fractions of multi-walled carbon nanotubes (MWNTs) were prepared by in situ polymerization. MWNTs were treated with an acid mixture and sulfoxide chloride in turn to increase the chemical compatibility of carbon nanotubes with the polyimide matrix. The modified MWNTs are dispersed homogeneously in the matrix while the structure of the PI and MWNTs structures are stable in the preparation process. The composite films hold preferable thermal stability as same as the pure PI. The dielectric constants of the composites decreased with the increasing frequency and increase sharply with the adding of MWNTs.

scholarly journals Continuous Flow Synthesis of Anticancer Drugs

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6992
Author(s):  
Mara Di Filippo ◽  
Marcus Baumann
Keyword(s):  
Anticancer Drugs ◽  
Continuous Flow ◽  
Flow Chemistry ◽  
Active Pharmaceutical Ingredient ◽  
Building Blocks ◽  
Short Review ◽  
Molecular Structures ◽  
Batch Processes ◽  
Continuous Flow Chemistry ◽  
The Impact

Continuous flow chemistry is by now an established and valued synthesis technology regularly exploited in academic and industrial laboratories to bring about the improved preparation of a variety of molecular structures. Benefits such as better heat and mass transfer, improved process control and safety, a small equipment footprint, as well as the ability to integrate in-line analysis and purification tools into telescoped sequences are often cited when comparing flow to analogous batch processes. In this short review, the latest developments regarding the exploitation of continuous flow protocols towards the synthesis of anticancer drugs are evaluated. Our efforts focus predominately on the period of 2016–2021 and highlight key case studies where either the final active pharmaceutical ingredient (API) or its building blocks were produced continuously. It is hoped that this manuscript will serve as a useful synopsis showcasing the impact of continuous flow chemistry towards the generation of important anticancer drugs.

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