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121 results on '"Heidari, Hamed"'

3. Correction: Structural characterization of a polycrystalline epitaxially-fused colloidal quantum dot superlattice by electron tomography

Author

Chu, Xiaolei, Heidari, Hamed, Abelson, Alex, Unruh, Davis, Hansen, Chase, Qian, Caroline, Zimanyi, Gergely, Law, Matt, and Moulé, Adam J

Subjects
Macromolecular and Materials Chemistry, Materials Engineering, Interdisciplinary Engineering
Abstract

The authors regret the following minor errors in the published article: In Section 2.1 (Materials), two chemicals, lead iodide and ethanol, were accidentally omitted from the list. The revised text should read:

Published
2020

4. Structural characterization of a polycrystalline epitaxially-fused colloidal quantum dot superlattice by electron tomography

Author

Chu, Xiaolei, Heidari, Hamed, Abelson, Alex, Unruh, Davis, Hansen, Chase, Qian, Caroline, Zimanyi, Gergely, Law, Matt, and Moulé, Adam J

Subjects
Macromolecular and Materials Chemistry, Chemical Sciences, Engineering, Chemical Engineering, Materials Engineering, Interdisciplinary Engineering, Macromolecular and materials chemistry, Chemical engineering, Materials engineering
Abstract

Three dimensional epitaxially-fused colloidal quantum dot (QD) superlattices (epi-SLs) feature exceptional electronic coupling and spatial order and are promising systems for studying the emergence of delocalized states and mini-band charge transport in self-assembled solids. However, energy disorder arising from structural defects and aperiodicity has so far resulted in charge carrier localization and slow hopping transport. Detailed 3D structural characterization is critical for rationally improving epi-SL structural perfection to trigger the formation of mini-bands. Here, we analyze the 3D structure of a 120 × 38 nm disc-shaped region of a PbSe QD epi-SL using full-tilt high-angle annular dark-field electron tomography. The high spatial resolution of the tomographic reconstruction (0.65 nm) enables determination of the center-of-mass coordinates of all 1846 QDs in the sample as well as the size and shape of the thousands of epitaxial connections (necks) between the QDs. The tomogram reveals the detailed crystallography and internal positional disorder of the three SL grains that constitute this sample. A map of the neck network is used to quantify relationships between neck number (the number of necks each QD possesses), average neck diameter, QD location in the film, and the nearest neighbor inter-QD distance and distance distribution. We find a strong positive correlation between neck number and local spatial order, suggesting that future improvements in neck connectivity are likely to simultaneously enhance the overall structural perfection of the epi-SLs. A kinetic Monte Carlo model is employed to estimate the electron mobility of the tomography sample and assess the impact of grain boundaries on charge transport. Our electron tomography study establishes a baseline for the quantitative statistical analysis of structural defects in 3D QD epi-SLs.

Published
2020

7. Formation and Thermal Stability of Gold-Silica Nanohybrids: Insight into the Mechanism and Morphology by Electron Tomography

Author

Kundu, Paromita, Heidari, Hamed, Bals, Sara, Ravishankar, N., and Van Tendeloo, Gustaaf

Subjects
Condensed Matter - Materials Science
Abstract

Gold-silica hybrids are appealing in different fields of applications like catalysis, sensors, drug delivery, and biotechnology. In most cases, the morphology and distribution of the hetero-units play significant roles in their functional behavior. Methods of synthesizing these hybrids, with variable ordering of the hetero-units, are replete; however, a complete characterization in three dimensions could not be achieved yet. A simple route to the synthesis of Au-decorated SiO2 spheres is demonstrated and a study on the 3D ordering of the hetero-units by scanning transmission electron microscopy (STEM) tomography is presented at the final stage, intermediate stages of formation, and after heating the hybrid. The final hybrid evolves from a soft self-assembled structure of Au nano-particles. The hybrid shows good thermal stability up to 400 C, beyond which the Au particles start migrating inside the SiO2 matrix. This study provides an insight in the formation mechanism and thermal stability of the structures which are crucial factors for designing and applying such hybrids in fields of catalysis and biotechnology. As the method is general, it can be applied to make similar hybrids based on SiO2 by tuning the reaction chemistry as needed.

Published
2015
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25. Interplay of Interfacial Layers and Blend Composition To Reduce Thermal Degradation of Polymer Solar Cells at High Temperature

Author

Ben Dkhil, Sadok, primary, Pfannmöller, Martin, additional, Schröder, Rasmus R., additional, Alkarsifi, Riva, additional, Gaceur, Meriem, additional, Köntges, Wolfgang, additional, Heidari, Hamed, additional, Bals, Sara, additional, Margeat, Olivier, additional, Ackermann, Jörg, additional, and Videlot-Ackermann, Christine, additional

Published
2018
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27. Triple-Modal Imaging of Magnetically-Targeted Nanocapsules in Solid Tumours In Vivo

Author

Bai, Jie, Wang, Julie T-W, Rubio, Noelia, Protti, Andrea, Heidari, Hamed, Elgogary, Riham, Southern, Paul, Al-Jamal, Wafa' T, Sosabowski, Jane K, Shah, Ajay M, Bals, Sara, Pankhurst, Quentin A, and Al-Jamal, Khuloud T

Subjects
Mice, Inbred BALB C, Research Support, Non-U.S. Gov't, Physics, equipment and supplies, Ferric Compounds, Multimodal Imaging, Disease Models, Animal, Magnetics, Nanocapsules, Neoplasms, Journal Article, Animals, Administration, Intravenous, Female, Human medicine, human activities
Abstract

Triple-modal imaging magnetic nanocapsules, encapsulating hydrophobic superparamagnetic iron oxide nanoparticles, are formulated and used to magnetically target solid tumours after intravenous administration in tumour-bearing mice. The engineered magnetic polymeric nanocapsules m-NCs are ~200 nm in size with negative Zeta potential and shown to be spherical in shape. The loading efficiency of superparamagnetic iron oxide nanoparticles in the m-NC was ~100%. Up to ~3- and ~2.2-fold increase in tumour uptake at 1 and 24 h was achieved, when a static magnetic field was applied to the tumour for 1 hour. m-NCs, with multiple imaging probes (e.g. indocyanine green, superparamagnetic iron oxide nanoparticles and indium-111), were capable of triple-modal imaging (fluorescence/magnetic resonance/nuclear imaging) in vivo. Using triple-modal imaging is to overcome the intrinsic limitations of single modality imaging and provides complementary information on the spatial distribution of the nanocarrier within the tumour. The significant findings of this study could open up new research perspectives in using novel magnetically-responsive nanomaterials in magnetic-drug targeting combined with multi-modal imaging.

Published
2016

31. Micro‐ and nanostructural characterization of melamine‐formaldehyde microcapsule shells using electron microscopy

Author

Heidari, Hamed, primary, Rivero, Guadalupe, additional, Idrissi, Hosni, additional, Ramachandran, Dhanya, additional, Cakir, Seda, additional, Egoavil, Ricardo, additional, Kurttepeli, Mert, additional, Crabbé, Amandine, additional, Hauffman, Tom, additional, Terryn, Herman, additional, Du Prez, Filip, additional, and Schryvers, Nick, additional

Published
2016
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32. Plasmonic Au@Pd Nanorods with Boosted Refractive Index Susceptibility and SERS Efficiency: A Multifunctional Platform for Hydrogen Sensing and Monitoring of Catalytic Reactions

Author

Rodal-Cedeira, Sergio, primary, Montes-García, Verónica, additional, Polavarapu, Lakshminarayana, additional, Solís, Diego Martínez, additional, Heidari, Hamed, additional, La Porta, Andrea, additional, Angiola, Marco, additional, Martucci, Alessandro, additional, Taboada, José M., additional, Obelleiro, Fernando, additional, Bals, Sara, additional, Pérez-Juste, Jorge, additional, and Pastoriza-Santos, Isabel, additional

Published
2016
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33. Melamine–Formaldehyde Microcapsules: Micro- and Nanostructural Characterization with Electron Microscopy

Author

Heidari, Hamed, primary, Rivero, Guadalupe, additional, Idrissi, Hosni, additional, Ramachandran, Dhanya, additional, Cakir, Seda, additional, Egoavil, Ricardo, additional, Kurttepeli, Mert, additional, Crabbé, Amandine C., additional, Hauffman, Tom, additional, Terryn, Herman, additional, Du Prez, Filip, additional, and Schryvers, Dominique, additional

Published
2016
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34. Toward High-Temperature Stability of PTB7-Based Bulk Heterojunction Solar Cells: Impact of Fullerene Size and Solvent Additive

Author

Dkhil, Sadok Ben, primary, Pfannmöller, Martin, additional, Saba, Maria Ilenia, additional, Gaceur, Meriem, additional, Heidari, Hamed, additional, Videlot-Ackermann, Christine, additional, Margeat, Olivier, additional, Guerrero, Antonio, additional, Bisquert, Juan, additional, Garcia-Belmonte, Germa, additional, Mattoni, Alessandro, additional, Bals, Sara, additional, and Ackermann, Jörg, additional

Published
2016
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35. Magnetic Drug Targeting: Preclinical in Vivo Studies, Mathematical Modeling, and Extrapolation to Humans

Author

Al-Jamal, Khuloud T., primary, Bai, Jie, additional, Wang, Julie Tzu-Wen, additional, Protti, Andrea, additional, Southern, Paul, additional, Bogart, Lara, additional, Heidari, Hamed, additional, Li, Xinjia, additional, Cakebread, Andrew, additional, Asker, Dan, additional, Al-Jamal, Wafa T., additional, Shah, Ajay, additional, Bals, Sara, additional, Sosabowski, Jane, additional, and Pankhurst, Quentin A., additional

Published
2016
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39. Toward High-Temperature Stability of PTB7-Based Bulk Heterojunction Solar Cells: Impact of Fullerene Size and Solvent Additive.

Author

Dkhil, Sadok Ben, Pfannmöller, Martin, Saba, Maria Ilenia, Gaceur, Meriem, Heidari, Hamed, Videlot‐Ackermann, Christine, Margeat, Olivier, Guerrero, Antonio, Bisquert, Juan, Garcia‐Belmonte, Germa, Mattoni, Alessandro, Bals, Sara, and Ackermann, Jörg

Subjects
SOLAR cells, THIOPHENE derivatives, FULLERENES, HIGH temperatures, HETEROJUNCTIONS, ADDITIVES, SOLVENTS, THERMAL stability
Abstract

The use of fullerene as acceptor limits the thermal stability of organic solar cells at high temperatures as their diffusion inside the donor leads to phase separation via Ostwald ripening. Here it is reported that fullerene diffusion is fully suppressed at temperatures up to 140 °C in bulk heterojunctions based on the benzodithiophene-based polymer (the poly[[4,8-bis[(2-ethylhexyl)oxy]-benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]-thieno[3,4-b]thiophenediyl]], (PTB7) in combination with the fullerene derivative [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM). The blend stability is found independently of the presence of diiodooctane (DIO) used to optimize nanostructuration and in contrast to PTB7 blends using the smaller fullerene derivative PC70BM. The unprecedented thermal stability of PTB7:PC70BM layers is addressed to local minima in the mixing enthalpy of the blend forming stable phases that inhibit fullerene diffusion. Importantly, although the nanoscale morphology of DIO processed blends is thermally stable, corresponding devices show strong performance losses under thermal stress. Only by the use of a high temperature annealing step removing residual DIO from the device, remarkably stable high efficiency solar cells with performance losses less than 10% after a continuous annealing at 140 °C over 3 days are obtained. These results pave the way toward high temperature stable polymer solar cells using fullerene acceptors. [ABSTRACT FROM AUTHOR]

Published
2017
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41. Plasmonic Nanodiamonds: Targeted Core–Shell Type Nanoparticles for Cancer Cell Thermoablation

Author

Rehor, Ivan, primary, Lee, Karin L., additional, Chen, Kevin, additional, Hajek, Miroslav, additional, Havlik, Jan, additional, Lokajova, Jana, additional, Masat, Milan, additional, Slegerova, Jitka, additional, Shukla, Sourabh, additional, Heidari, Hamed, additional, Bals, Sara, additional, Steinmetz, Nicole F., additional, and Cigler, Petr, additional

Published
2014
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50. Shelf Life Degradation of Bulk Heterojunction Solar Cells: Intrinsic Evolution of Charge Transfer Complex.

Author

Guerrero, Antonio, Heidari, Hamed, Ripolles, Teresa S., Kovalenko, Alexander, Pfannmöller, Martin, Bals, Sara, Kauffmann, Louis‐Dominique, Bisquert, Juan, and Garcia‐Belmonte, Germà

Subjects
*SOLAR cells, *CHARGE transfer, *MASS transfer, *DIRECT energy conversion, *ELECTRON donor-acceptor complexes
Abstract

Achievement of long-term stability of organic photovoltaics is currently one of the major topics for this technology to reach maturity. Most of the techniques used to reveal degradation pathways are destructive and/or do not allow for real-time measurements in operating devices. Here, three different, nondestructive techniques able to provide real-time information, namely, film absorbance, capacitance-voltage ( C-V), and impedance spectroscopy (IS), are combined over a period of 1 year using non-accelerated intrinsic degradation conditions. It is discerned between chemical modifications in the active layer, physical processes taking place in the bulk of the blend from those at the active layer/contact interfaces. In particular, it is observed that during the ageing experiment, the main source for device performance degradation is the formation of donor-acceptor charge-transfer complex ( [ABSTRACT FROM AUTHOR]

Published
2015
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