Search

Your search keyword '"Barnsley, Lester"' showing total 42 results
Start Over Author "Barnsley, Lester"
42 results on '"Barnsley, Lester"'

2. Field Dependence of Magnetic Disorder in Nanoparticles

Author

Zákutná, Dominika, Nižňanský, Daniel, Barnsley, Lester C., Babcock, Earl, Salhi, Zahir, Feoktystov, Artem, Honecker, Dirk, and Disch, Sabrina

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The performance characteristics of magnetic nanoparticles towards application, e.g. in medicine, imaging, or as sensors, is directly determined by their magnetization relaxation and total magnetic moment. In the commonly assumed picture, nanoparticles have a constant overall magnetic moment originating from the magnetization of the single-domain particle core surrounded by a surface region hosting spin disorder. In contrast, this work demonstrates the significant increase of the magnetic moment of ferrite nanoparticles with applied magnetic field. At low magnetic field, the homogeneously magnetized particle core initially coincides in size with the structurally coherent grain of 12.8(2) nm diameter, indicating a strong coupling between magnetic and structural disorder. Applied magnetic fields gradually polarize the uncorrelated, disordered surface spins, resulting in a magnetic volume more than 20\% larger than the structurally coherent core. The intraparticle magnetic disorder energy increases sharply towards the defect-rich surface as established by the field-dependence of the magnetization distribution. In consequence, these findings illustrate how the nanoparticle magnetization overcomes structural surface disorder. This new concept of intraparticle magnetization is deployable to other magnetic nanoparticle systems, where the in-depth knowledge of spin disorder and associated magnetic anisotropies will be decisive for a rational nanomaterials design., Comment: 40 pages, 14 figures, extensively revised (including change of title, appendix added)

Published
2019
Full Text
View/download PDF

8. A Polymer Acceptor With Grafted Small Molecule Acceptor Unit for Efficient All Polymer Organic Solar Cells

Author

Shi, Wendi, primary, Huang, Yuzhong, additional, Ma, Kangqiao, additional, Si, Xiaodong, additional, Feng, Wanying, additional, Wang, Ruohan, additional, Guo, Jiaxin, additional, Ma, Wei, additional, Wang, Shijie, additional, Clulow, Andrew, additional, Barnsley, Lester, additional, Yao, Zhaoyang, additional, Li, Chenxi, additional, Wan, Xiangjian, additional, and Chen, Yongsheng, additional

Published
2023
Full Text
View/download PDF

11. Evolution of Pore Structure in Organic-Lean and Organic-Rich Mudrocks

Author

Rezaeyan, Amirsaman, Kampman, Niko, Pipich, Vitaliy, Barnsley, Lester C., Rother, Gernot, Magill, Clayton, Ma, Jingsheng, and Busch, Andreas

Abstract

The pore structure of mudrocks is a key characteristic to evaluate flow behavior through these rocks. Although significant advances have been made to resolve pore characteristics, porosity evolution, or pore connectivity, there is still insufficient knowledge linking porosity evolution to flow and transport in mudrocks. To better understand these links, we conducted very small-angle (VSANS) and small-angle neutron scattering (SANS) experiments on 13 sets of mudrocks from global locations, characterized by differences in composition, maturity, and depositional environment. Our results indicate that a homogeneous pore structure reflects a stable and low-energy depositional environment. Organic-lean mudrocks mainly contain pores <10 nm, which restricts flow and is beneficial for, e.g., caprock seal integrity. Increasing maturity as a result of increasing burial depth, and therefore, temperature leads to porosity evolution. In organic-rich mudrocks (ORMs), this happens through the generation of organic matter pores and pore preservation around diagenetically formed carbonates. ORMs mainly contain macropores (>50 nm), favoring production from, e.g., unconventional reservoirs. SANS-derived pore size distributions will help to better understand fluid imbibition and flow properties in mudrocks through comprehensive quantitative characterization of the nano- to micron scale pore network conduits and their relationships to burial diagenesis.

Published
2023
Full Text
View/download PDF

17. Structural Properties of Micelles Formed by Telechelic Pentablock Quaterpolymers with pH-Responsive Midblocks and Thermoresponsive End Blocks in Aqueous Solution

Author

Jung, Florian A., Panteli, Panayiota A., Ko, Chia-Hsin, Kang, Jia-Jhen, Barnsley, Lester C., Tsitsilianis, Constantinos, Patrickios, Costas S., Papadakis, Christine M., Patrickios, Costas S. [0000-0001-8855-0370], Tsitsilianis, Constantinos [0000-0002-7265-9037], and Panteli, Panayiota A. [0000-0001-7920-0934]

Subjects
chemistry.chemical_classification, Aqueous solution, Hydrodynamic radius, Polymers and Plastics, Organic Chemistry, 02 engineering and technology, Polymer, 010402 general chemistry, 021001 nanoscience & nanotechnology, Methacrylate, 01 natural sciences, Micelle, Polyelectrolyte, 0104 chemical sciences, Inorganic Chemistry, chemistry.chemical_compound, chemistry, Dynamic light scattering, Chemical engineering, ddc:540, Materials Chemistry, 0210 nano-technology, Ethylene glycol
Abstract

We investigated the structural properties of dynamic micelles arising from the self-assembly of the multiresponsive pentablock quaterpolymer P(nBuMA8-co-TEGMA8)-b-PDMAEMA50-b-PEG46-b-PDMAEMA50-b-P(nBuMA8-co-TEGMA8) (nBuMA, TEGMA, DMAEMA, and EG are n-butyl methacrylate, tri(ethylene glycol) methyl ether methacrylate, 2-(dimethylamino)ethyl methacrylate, and ethylene glycol, respectively) in aqueous solution using a combination of scattering methods. In this multisegmented polymer, a pH-responsive BAB triblock copolymer from the weak cationic polyelectrolyte PDMAEMA and the hydrophilic PEG is end-capped by two blocks comprising random sequences of thermoresponsive TEGMA units and hydrophobic nBuMA units. Dynamic light scattering revealed the existence of single micelles and small clusters in dilute aqueous solution. The hydrodynamic radius of the micelles depends strongly on pH and temperature. The inner structure of the micelles was investigated by small-angle X-ray scattering, small-angle neutron scattering, and static light scattering, and micelles with a hydrophobic core containing a rather high fraction of water and a strongly swollen corona were found. The ratio of loops and dangling ends depends on temperature and pH. 52 24 9746 9758

Published
2019

19. Stabilizing the Solid‐Electrolyte Interphase with Polyacrylamide for High‐Voltage Aqueous Lithium‐Ion Batteries

Author

Hou, Xu, primary, Wang, Rui, additional, He, Xin, additional, Pollard, Travis P, additional, Ju, Xiaokang, additional, Du, Leilei, additional, Paillard, Elie, additional, Frielinghaus, Henrich, additional, Barnsley, Lester C., additional, Borodin, Oleg, additional, Xu, Kang, additional, Winter, Martin, additional, and Li, Jie, additional

Published
2021
Full Text
View/download PDF

20. Engineering Challenges in BioSAXS for Australian Synchrotron

Author

Venkatesan, Sudharshan, Barnsley, Lester, Clulow, Andrew, Conesa-Zamora, Gonzalo, Grubb, Robert, Hamedi, Navid, Jensen, Brian, Kamma-Lorger, Christina, Mazonowicz, Antony, Roy, Clinton, and Samardzic-Boban, Vesna

Subjects
Physics::Accelerator Physics, Beamlines and front ends, Accelerator Physics
Abstract

The Biological Small Angle X-Ray Scattering (BioSAXS) beamline is the third beamline designed, developed and soon to be installed as part of BRIGHT Program at the Australian Synchrotron. The BioSAXS beamline will allow highly radiation sensitive samples to be studied at high flux. The beamline will offer increased efficiency, and data quality, for all liquid phase scattering experiments, allowing measurement of new and novel samples, and experiments, that otherwise would not be possible. The BioSAXS beamline will accommodate a wide range of experiments by offering a q-range of ~ 0.001 - 4 ��-1 and an optical design optimized for high flux (~5x10����� ph/s) x-rays. At this flux rate, BioSAXS will offer users one of the highest flux beamlines in the world. To achieve this, the beamline will use a superconducting undulator insertion device, double multilayer monochromator, and vertical and horizontal bending mirrors, providing flexibility in optical configurations. The beamline will primarily collect data in a fully unfocussed mode. BioSAXS will also be able to achieve a fully focused and a vertically focussed beam. This subsequent variation in the beam position at sample is accommodated through fully automated motion in 5 axes at the in-vacuum detector stage and 4 axes in the sample table. The design of these components allows smooth transition in camera lengths and improved signal to noise ratio. This paper presents the various engineering challenges in this high flux design, including thermal management of critical components, design developments to accommodate the various operational modes and various stages of the Photon Delivery System and Experimental Station components. The paper aims to present details of design, FEA results and approaches taken to solve problems., Proceedings of the 11th Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation, MEDSI2020, Chicago, IL, USA

Published
2021
Full Text
View/download PDF

22. Magnetic Nanoparticles: Unravelling Magnetic Nanochain Formation in Dispersion for In Vivo Applications (Adv. Mater. 24/2021)

Author

Nandakumaran, Nileena, primary, Barnsley, Lester, additional, Feoktystov, Artem, additional, Ivanov, Sergei A., additional, Huber, Dale L., additional, Fruhner, Lisa S., additional, Leffler, Vanessa, additional, Ehlert, Sascha, additional, Kentzinger, Emmanuel, additional, Qdemat, Asma, additional, Bhatnagar‐Schöffmann, Tanvi, additional, Rücker, Ulrich, additional, Wharmby, Michael T., additional, Cervellino, Antonio, additional, Dunin‐Borkowski, Rafal E., additional, Brückel, Thomas, additional, and Feygenson, Mikhail, additional

Published
2021
Full Text
View/download PDF

23. Unravelling Magnetic Nanochain Formation in Dispersion for In Vivo Applications

Author

Nandakumaran, Nileena, primary, Barnsley, Lester, additional, Feoktystov, Artem, additional, Ivanov, Sergei A., additional, Huber, Dale L., additional, Fruhner, Lisa S., additional, Leffler, Vanessa, additional, Ehlert, Sascha, additional, Kentzinger, Emmanuel, additional, Qdemat, Asma, additional, Bhatnagar‐Schöffmann, Tanvi, additional, Rücker, Ulrich, additional, Wharmby, Michael T., additional, Cervellino, Antonio, additional, Dunin‐Borkowski, Rafal E., additional, Brückel, Thomas, additional, and Feygenson, Mikhail, additional

Published
2021
Full Text
View/download PDF

27. Not just a fluidifying effect: omega-3 phospholipids induce formation of non-lamellar structures in biomembranes

Author

de Santis, Augusta, primary, Vitiello, Giuseppe, additional, Appavou, Marie-Sousai, additional, Scoppola, Ernesto, additional, Fragneto, Giovanna, additional, Barnsley, Lester C., additional, Clifton, Luke A., additional, Ottaviani, Maria Francesca, additional, Paduano, Luigi, additional, Russo Krauss, Irene, additional, and D’Errico, Gerardino, additional

Published
2020
Full Text
View/download PDF

36. Optimized shapes of magnetic arrays for drug targeting applications

Author

Barnsley, Lester C., Carugo, Dario, and Stride, Eleanor

Abstract

Arrays of permanent magnet elements have been utilized as light-weight, inexpensive sources for applying external magnetic fields in magnetic drug targeting applications, but they are extremely limited in the range of depths over which they can apply useful magnetic forces. In this paper, designs for optimized magnet arrays are presented, which were generated using an optimization routine to maximize the magnetic force available from an arbitrary arrangement of magnetized elements, depending on a set of design parameters including the depth of targeting (up to 50 mm from the magnet) and direction of force required. A method for assembling arrays in practice is considered, quantifying the difficulty of assembly and suggesting a means for easing this difficulty without a significant compromise to the applied field or force. Finite element simulations of in vitro magnetic retention experiments were run to demonstrate the capability of a subset of arrays to retain magnetic microparticles against flow. The results suggest that, depending on the choice of array, a useful proportion of particles (more than 10%) could be retained at flow velocities up to 100 mm/s or to depths as far as 50 mm from the magnet. Finally, the optimization routine was used to generate a design for a Halbach array optimized to deliver magnetic force to a depth of 50 mm inside the brain.

Published
2016

41. Enhanced magnetic microcytometer with 3D flow focusing for cell enumeration.

Author

Martins, Marco, Taouallah, Amal, Fernandes, João, Silva, Bruno F. B., Diéguez, Lorena, Espiña, Begoña, Chícharo, Alexandre, Freitas, Paulo P., Barnsley, Lester C., and Cardoso, Susana

Subjects
FLOW cytometry, MICROFLUIDICS, MAGNETIC sensors, CELL imaging, HYDRODYNAMICS
Abstract

We report the design and characterization of a lateral and vertical hydrodynamic focusing feature for whole cell detection on a miniaturized flow cytometer. The developed system, based on magnetic sensing, incorporates spin valve sensors on the bottom of the microfluidic channels that detect cells labeled with magnetic beads. An adaptable 3D hydrodynamic focusing system was developed that pushes labeled cells towards the bottom of the microchannel, closer to the sensors, allowing increased signal amplitude for cells labeled with magnetic beads and enhanced discrimination of labeled cells. Fluorescence microscopy indicates that the lateral and vertical hydrodynamic focusing effect was adequately implemented, consistent with simulation predictions. The sensitivity of the system to detect labeled cells was improved by at least two-fold. By estimating the coverage of magnetic beads on cells, the signal from labeled cells could be predicted using a mathematical model, which also demonstrated the sensitivity of the signal to the height of the cells relative to the sensor. The system is versatile allowing interchangeable flow rates for cells with different diameters. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
View/download PDF

42. Exchange Bias in Manganese Alloys with Mixed Magnetic Behaviour

Author

Barnsley, Lester Clinton

Subjects
Exchange bias, Manganese alloys, Mixed magnetic behaviour, Stoner-Wohlfarth model, Spin glass materials
Abstract

Exchange bias has been a well known property of materials consisting of a ferromagnet interfaced with an antiferromagnet for many years, and the anisotropy resulting from the interaction has recently been nominated as a possible means for overcoming the superparamagnetic limit in high-density magnetic information storage media. However, a generalized theoretical description of the phenomenon remains elusive. More recently, analogues between the exchange bias eect and the behaviours of spin glass materials have become increasingly recognized. In this thesis, the analogues between exchange bias and spin glass systems are explored in a set of concentrated spin glass samples that exhibit a strong sensitivity to short range order of magnetic entities. A number of models were developed to analyze and account for the measurements of magnetization made on these samples. The rst was a simple, empirical model, based on an approximation of non-interacting, monodisperse, superparamagnetic clusters against a paramagnetic background to t single branches of minor hysteresis loops. In this model, the parameter to describe the coercive eld was added ad hoc. Another, more sophisticated, model was based on a modied Stoner-Wohlfarth expression for magnetic clusters and applied to the data using Monte Carlo simulations. The best ts resulted from this model when the cluster easy axis orientations were allowed to have a Gaussian distribution.

Published
2012

Catalog

Books, media, physical & digital resources
See catalog results