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Li H, Wang J, Tjardts T, Barg I, Qiu H, Müller M, Krahmer J, Askari S, Veziroglu S, Aktas C, Kienle L, Benedikt J. Plasma-Engineering of Oxygen Vacancies on NiCo 2 O 4 Nanowires with Enhanced Bifunctional Electrocatalytic Performance for Rechargeable Zinc-air Battery. Small 2024:e2310660. [PMID: 38164883 DOI: 10.1002/smll.202310660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/17/2023] [Indexed: 01/03/2024]
Abstract
Designing an efficient, durable, and inexpensive bifunctional electrocatalyst toward oxygen evolution reactions (OER) and oxygen reduction reactions (ORR) remains a significant challenge for the development of rechargeable zinc-air batteries (ZABs). The generation of oxygen vacancies plays a vital role in modifying the surface properties of transition-metal-oxides (TMOs) and thus optimizing their electrocatalytic performances. Herein, a H2 /Ar plasma is employed to generate abundant oxygen vacancies at the surfaces of NiCo2 O4 nanowires. Compared with the Ar plasma, the H2 /Ar plasma generated more oxygen vacancies at the catalyst surface owing to the synergic effect of the Ar-related ions and H-radicals in the plasma. As a result, the NiCo2 O4 catalyst treated for 7.5 min in H2 /Ar plasma exhibited the best bifunctional electrocatalytic activities and its gap potential between Ej = 10 for OER and E1/2 for ORR is even smaller than that of the noble-metal-based catalyst. In situ electrochemical experiments are also conducted to reveal the proposed mechanisms for the enhanced electrocatalytic performance. The rechargeable ZABs, when equipped with cathodes utilizing the aforementioned catalyst, achieved an outstanding charge-discharge gap, as well as superior cycling stability, outperforming batteries employing noble-metal catalyst counterparts.
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Affiliation(s)
- He Li
- Institute of Experimental and Applied Physics, Kiel University, Leibnizstraße 19, D-24098, Kiel, Germany
| | - Jihao Wang
- Institute of Inorganic Chemistry, Kiel University, Max-Eyth-Straße 2/Otto-Hahn-Platz 6, D-24118., Kiel, Germany
| | - Tim Tjardts
- Chair for Multicomponent Materials, Department of Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143, Kiel, Germany
| | - Igor Barg
- Chair for Multicomponent Materials, Department of Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143, Kiel, Germany
| | - Haoyi Qiu
- Chair for Functional Nanomaterials, Department of Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143, Kiel, Germany
| | - Martin Müller
- Chair for Synthesis and Real Structure, Department of Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143, Kiel, Germany
| | - Jan Krahmer
- Institute of Inorganic Chemistry, Kiel University, Max-Eyth-Straße 2/Otto-Hahn-Platz 6, D-24118., Kiel, Germany
| | - Sadegh Askari
- Department of Fiber and Polymer Technology, KTH Royal Institute of Technology, Stockholm, SE-10044, Sweden
| | - Salih Veziroglu
- Chair for Multicomponent Materials, Department of Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143, Kiel, Germany
- Kiel Nano, Surface, and Interface Science KiNSIS, Kiel University, Christian-Albrechts-Platz 4, D-24118, Kiel, Germany
| | - Cenk Aktas
- Chair for Multicomponent Materials, Department of Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143, Kiel, Germany
| | - Lorenz Kienle
- Chair for Synthesis and Real Structure, Department of Materials Science, Faculty of Engineering, Kiel University, Kaiserstraße 2, D-24143, Kiel, Germany
- Kiel Nano, Surface, and Interface Science KiNSIS, Kiel University, Christian-Albrechts-Platz 4, D-24118, Kiel, Germany
| | - Jan Benedikt
- Institute of Experimental and Applied Physics, Kiel University, Leibnizstraße 19, D-24098, Kiel, Germany
- Kiel Nano, Surface, and Interface Science KiNSIS, Kiel University, Christian-Albrechts-Platz 4, D-24118, Kiel, Germany
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Askari S, Bastany Z, Shadgan B, Dumont GA. Implementing Effective Noise Reduction Techniques in Implantable NIRS Sensors. Annu Int Conf IEEE Eng Med Biol Soc 2023; 2023:1-5. [PMID: 38082783 DOI: 10.1109/embc40787.2023.10341128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Near-Infrared Spectroscopy (NIRS) is a noninvasive optical method widely used for evaluating tissue hemodynamics and various physiological characteristics. Despite its advantages, NIRS faces limitations in light sampling depth and spatial resolution, which has led to the development of implantable NIRS sensors. However, these implantable sensors are prone to Common-Mode Voltage (CMV) interference due to their increased sensor-to-tissue capacitance, which can compromise the signal-to-noise ratio and accuracy of measurements.In this paper, we present a novel active CMV reduction technique that enhances the signal-to-noise ratio of NIRS signals. We propose an electrical model of a patient's body and NIRS sensor to characterize the CMV interference and the active CMV cancellation (ACC) electronic circuit. The ACC circuit measures CMV through a common-mode amplifier, which then inverts and introduces the amplified signal to the patient's body via an additional surface electrode. This technique effectively attenuates the CMV (50 and 60 Hz) by 80 to 90 dB, significantly improving the signal quality without causing system instability.The method has been validated through both analytical simulations and experimental measurements, demonstrating the circuit's ability to suppress CMV within a bandwidth of 0.1 to 100 Hz. Experimental verification of the active noise cancellation method was conducted by recording data from the fingertip and palm, showing effective suppression of the CMV. The proposed method has substantial clinical relevance as it enhances the reliability and accuracy of implantable NIRS sensors, enabling more precise monitoring of internal organs and improved patient care.
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Hosseinpoor H, Moghadam Farid S, Iraji A, Askari S, Edraki N, Hosseini S, Jamshidzadeh A, Larijani B, Attarroshan M, Pirhadi S, Mahdavi M, Khoshneviszadeh M. Anti-melanogenesis and anti-tyrosinase properties of aryl-substituted acetamides of phenoxy methyl triazole conjugated with thiosemicarbazide: Design, synthesis and biological evaluations. Bioorg Chem 2021; 114:104979. [PMID: 34140181 DOI: 10.1016/j.bioorg.2021.104979] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/27/2021] [Accepted: 05/05/2021] [Indexed: 10/21/2022]
Abstract
A series of aryl phenoxy methyl triazole conjugated with thiosemicarbazides were designed, synthesized, and evaluated for their tyrosinase inhibitory activities in the presence of l-dopa and l-tyrosine as substrates. All the compounds showed tyrosinase inhibition in the sub-micromolar concentration. Among the derivatives, compound 9j bearing benzyl displayed exceptionally high potency against tyrosinase with IC50 value of 0.11 μM and 0.17 μM in the presence of l-tyrosine and l-dopa as substrates which is significantly lower than that of kojic acid as the positive control with an IC50 value of 9.28 μM for l-tyrosine and 9.30 μM for l-dopa. According to Lineweaver-Burk plot, 9j demonstrated an uncompetitive type of inhibition in the kinetic assay. Also, in vitro antioxidant activities determined by DPPH assay recorded an IC50 value of 68.43 μM for 9i. The melanin content of 9j was determined on B16F10 melanoma human cells which demonstrated a significant reduction of the melanin content. Moreover, the binding energies corresponding to the same ligand as well as computer-aided drug-likeness and pharmacokinetic studies were also carried out. Compound 9j also possessed metal chelation potential correlated to its high anti-TYR activity.
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Affiliation(s)
- Hona Hosseinpoor
- Department of Medicinal Chemistry, Faculty of Pharmacy, Shiraz University of Medical Sciences, 71345 Shiraz, Iran
| | - Sara Moghadam Farid
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Aida Iraji
- Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, 71348 Shiraz, Iran; Central Research laboratory, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Sadegh Askari
- Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran, Iran
| | - Najmeh Edraki
- Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, 71348 Shiraz, Iran
| | - Samanesadat Hosseini
- Phytochemistry Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Akram Jamshidzadeh
- Department of Pharmacology and Toxicology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Bagher Larijani
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahshid Attarroshan
- Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, 71348 Shiraz, Iran
| | - Somayeh Pirhadi
- Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, 71348 Shiraz, Iran
| | - Mohammad Mahdavi
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
| | - Mehdi Khoshneviszadeh
- Department of Medicinal Chemistry, Faculty of Pharmacy, Shiraz University of Medical Sciences, 71345 Shiraz, Iran; Medicinal and Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, 71348 Shiraz, Iran.
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Askari S, Montazerin N, Fazel Zarandi M. Modeling energy flow in natural gas networks using time series disaggregation and fuzzy systems tuned by particle swarm optimization. Appl Soft Comput 2020. [DOI: 10.1016/j.asoc.2020.106332] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Haq AU, Buerkle M, Askari S, Rocks C, Ni C, Švrček V, Maguire P, Irvine JTS, Mariotti D. Controlling the Energy-Level Alignment of Silicon Carbide Nanocrystals by Combining Surface Chemistry with Quantum Confinement. J Phys Chem Lett 2020; 11:1721-1728. [PMID: 32040322 PMCID: PMC7145349 DOI: 10.1021/acs.jpclett.9b03828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/10/2020] [Indexed: 06/10/2023]
Abstract
The knowledge of band edges in nanocrystals (NCs) and quantum-confined systems is important for band alignment in technologically significant applications such as water purification, decomposition of organic compounds, water splitting, and solar cells. While the band energy diagram of bulk silicon carbides (SiCs) has been studied extensively for decades, very little is known about its evolution in SiC NCs. Moreover, the interplay between quantum confinement and surface chemistry gives rise to unusual electronic properties and remains barely understood. Here, we report for the first time the complete band energy diagram of SiC NCs synthesized such that they span the regime from strong to intermediate to weak quantum confinement. The absolute positions of the highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbitals show clear size dependence. While the HOMO level follows the expected behavior for quantum-confined electronic states, the LUMO energy shifts below the bulk conduction band minimum, which cannot be explained by a simple quantum confinement caused by the size effect. We show that this effect is a result of the interplay between quantum confinement and the formation of surface states due to partial and site-selective oxygen passivation.
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Affiliation(s)
- Atta Ul Haq
- Nanotechnology
& Integrated Bioengineering Centre (NIBEC), Ulster University, Shore Road, Newtownabbey BT37 0QB, United Kingdom
| | - Marius Buerkle
- National
Institute of Advanced Industrial Science and Technology (AIST), Central 2, Tsukuba 305-8568, Japan
| | - Sadegh Askari
- Institute
for Experimental and Applied Physics, Christian-Albrechts-Universität
zu Kiel, Leibnizstraße
17, 24118 Kiel, Germany
| | - Conor Rocks
- Nanotechnology
& Integrated Bioengineering Centre (NIBEC), Ulster University, Shore Road, Newtownabbey BT37 0QB, United Kingdom
| | - Chengsheng Ni
- School
of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, United Kingdom
- College
of Resources and Environment, Southwest
University, 400715, Chongqing, China
| | - Vladimir Švrček
- National
Institute of Advanced Industrial Science and Technology (AIST), Central 2, Tsukuba 305-8568, Japan
| | - Paul Maguire
- Nanotechnology
& Integrated Bioengineering Centre (NIBEC), Ulster University, Shore Road, Newtownabbey BT37 0QB, United Kingdom
| | - John T. S. Irvine
- School
of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, United Kingdom
| | - Davide Mariotti
- Nanotechnology
& Integrated Bioengineering Centre (NIBEC), Ulster University, Shore Road, Newtownabbey BT37 0QB, United Kingdom
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6
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Askari S, Mariotti D, Stehr JE, Benedikt J, Keraudy J, Helmersson U. Low-Loss and Tunable Localized Mid-Infrared Plasmons in Nanocrystals of Highly Degenerate InN. Nano Lett 2018; 18:5681-5687. [PMID: 30137994 DOI: 10.1021/acs.nanolett.8b02260] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Plasmonic response of free charges confined in nanostructures of plasmonic materials is a powerful means for manipulating the light-material interaction at the nanoscale and hence has influence on various relevant technologies. In particular, plasmonic materials responsive in the mid-infrared range are technologically important as the mid-infrared is home to the vibrational resonance of molecules and also thermal radiation of hot objects. However, the development of the field is practically challenged with the lack of low-loss materials supporting high quality plasmons in this range of the spectrum. Here, we demonstrate that degenerately doped InN nanocrystals (NCs) support tunable and low-loss plasmon resonance spanning the entire midwave infrared range. Modulating free-carrier concentration is achieved by engineering nitrogen-vacancy defects (InN1- x, 0.017 < x < 0.085) in highly degenerate NCs using a nonequilibrium gas-phase growth process. Despite the significant reduction in the carrier mobility relative to intrinsic InN, the mobility in degenerate InN NCs (>60 cm2/(V s)) remains considerably higher than the carrier mobility reported for other materials NCs such as doped metal oxides, chalcogenides, and noble metals. These findings demonstrate feasibility of controlled tuning of infrared plasmon resonances in a low-loss material of III-V compounds and open a gateway to further studies of these materials nanostructures for infrared plasmonic applications.
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Affiliation(s)
- Sadegh Askari
- Department of Physics , Linköping University , SE-581 83 Linköping , Sweden
- Institute for Experimental and Applied Physics , Christian-Albrechts-Universität zu Kiel , Leibnizstraße 17 , 24118 Kiel , Germany
| | - Davide Mariotti
- Nanotechnology & Integrated Bioengineering Centre (NIBEC) , Ulster University , BT37 0QB , Northern Ireland , United Kingdom
| | - Jan Eric Stehr
- Department of Physics , Linköping University , SE-581 83 Linköping , Sweden
| | - Jan Benedikt
- Institute for Experimental and Applied Physics , Christian-Albrechts-Universität zu Kiel , Leibnizstraße 17 , 24118 Kiel , Germany
| | - Julien Keraudy
- Department of Physics , Linköping University , SE-581 83 Linköping , Sweden
| | - Ulf Helmersson
- Department of Physics , Linköping University , SE-581 83 Linköping , Sweden
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7
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Askari S, Montazerin N, Fazel Zarandi M. Generalized Possibilistic Fuzzy C-Means with novel cluster validity indices for clustering noisy data. Appl Soft Comput 2017. [DOI: 10.1016/j.asoc.2016.12.049] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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8
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Marzpour Shalmani F, Halladj R, Askari S. Physicochemical characterization to assess Ni and Zn incorporation into zeotype SAPO-34 nanoparticles synthesized with different mixing methods through ultrasound-promoted crystallization. RSC Adv 2017. [DOI: 10.1039/c7ra00272f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The effect of synthesis parameters on the properties of Ni- and Zn-containing SAPO-34 nanoparticles prepared by applying insonation was investigated to elucidate how the isomorphous substitution of metal ions was influenced by synthesis conditions.
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Affiliation(s)
- F. Marzpour Shalmani
- Faculty of Chemical Engineering
- Amirkabir University of Technology (Tehran Polytechnic)
- Tehran
- Iran
| | - R. Halladj
- Faculty of Chemical Engineering
- Amirkabir University of Technology (Tehran Polytechnic)
- Tehran
- Iran
| | - S. Askari
- Department of Chemical Engineering, Science and Research Branch
- Islamic Azad University
- Tehran
- Iran
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9
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Askari S, Montazerin N, Zarandi MF, Hakimi E. Generalized entropy based possibilistic fuzzy C-Means for clustering noisy data and its convergence proof. Neurocomputing 2017. [DOI: 10.1016/j.neucom.2016.09.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Askari S, Ul Haq A, Macias-Montero M, Levchenko I, Yu F, Zhou W, Ostrikov KK, Maguire P, Svrcek V, Mariotti D. Ultra-small photoluminescent silicon-carbide nanocrystals by atmospheric-pressure plasmas. Nanoscale 2016; 8:17141-17149. [PMID: 27722686 DOI: 10.1039/c6nr03702j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Highly size-controllable synthesis of free-standing perfectly crystalline silicon carbide nanocrystals has been achieved for the first time through a plasma-based bottom-up process. This low-cost, scalable, ligand-free atmospheric pressure technique allows fabrication of ultra-small (down to 1.5 nm) nanocrystals with very low level of surface contamination, leading to fundamental insights into optical properties of the nanocrystals. This is also confirmed by their exceptional photoluminescence emission yield enhanced by more than 5 times by reducing the nanocrystals sizes in the range of 1-5 nm, which is attributed to quantum confinement in ultra-small nanocrystals. This method is potentially scalable and readily extendable to a wide range of other classes of materials. Moreover, this ligand-free process can produce colloidal nanocrystals by direct deposition into liquid, onto biological materials or onto the substrate of choice to form nanocrystal films. Our simple but efficient approach based on non-equilibrium plasma environment is a response to the need of most efficient bottom-up processes in nanosynthesis and nanotechnology.
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Affiliation(s)
- Sadegh Askari
- Nanotechnology & Integrated Bio-Engineering Centre, Ulster University, BT37 0QB, UK. and Department of Physics, Chemistry and biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
| | - Atta Ul Haq
- Nanotechnology & Integrated Bio-Engineering Centre, Ulster University, BT37 0QB, UK.
| | - Manuel Macias-Montero
- Nanotechnology & Integrated Bio-Engineering Centre, Ulster University, BT37 0QB, UK.
| | - Igor Levchenko
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane QLD 4000, Australia
| | - Fengjiao Yu
- EaStChem, School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Wuzong Zhou
- EaStChem, School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Kostya Ken Ostrikov
- Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane QLD 4000, Australia and CSIRO-QUT Joint Sustainable Processes and Devices Laboratory, Commonwealth Scientific and Industrial Research Organization, P.O. Box 218, Lindfield, NSW 2070, Australia
| | - Paul Maguire
- Nanotechnology & Integrated Bio-Engineering Centre, Ulster University, BT37 0QB, UK.
| | - Vladimir Svrcek
- Research Center of Photovoltaics, National Institute of Advanced Industrial Science and Technology-AIST, Central 2, Tsukuba, Japan
| | - Davide Mariotti
- Nanotechnology & Integrated Bio-Engineering Centre, Ulster University, BT37 0QB, UK.
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Zhang RC, Sun D, Lu A, Askari S, Macias-Montero M, Joseph P, Dixon D, Ostrikov K, Maguire P, Mariotti D. Microplasma Processed Ultrathin Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Thermal Transport Performance. ACS Appl Mater Interfaces 2016; 8:13567-13572. [PMID: 27153343 DOI: 10.1021/acsami.6b01531] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This Research Article reports on the enhancement of the thermal transport properties of nanocomposite materials containing hexagonal boron nitride in poly(vinyl alcohol) through room-temperature atmospheric pressure direct-current microplasma processing. Results show that the microplasma treatment leads to exfoliation of the hexagonal boron nitride in isopropyl alcohol, reducing the number of stacks from >30 to a few or single layers. The thermal diffusivity of the resulting nanocomposites reaches 8.5 mm(2) s(-1), 50 times greater than blank poly(vinyl alcohol) and twice that of nanocomposites containing nonplasma treated boron nitride nanosheets. From TEM analysis, we observe much less aggregation of the nanosheets after plasma processing along with indications of an amorphous carbon interfacial layer, which may contribute to stable dispersion of boron nitride nanosheets in the resulting plasma treated colloids.
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Affiliation(s)
- Ri-Chao Zhang
- Department of Chemical and Biological Engineering, Zhejiang University , Hangzhou, 310002, PR China
- School of Mechanical and Aerospace Engineering, Queen's University Belfast, BT9 5AH, U.K
- Nanotechnology and Integrated Bioengineering Centre (NIBEC), University of Ulster , Newtownabbey, BT37 0QB, Northern Ireland, U.K
| | - Dan Sun
- School of Mechanical and Aerospace Engineering, Queen's University Belfast, BT9 5AH, U.K
| | - Ai Lu
- Institute of Chemical Materials, China Academy of Engineering Physics , Mianyang 621900, Sichuan People's Republic of China
| | - Sadegh Askari
- Department of Physics, Chemistry and Biology (IFM)/Plasma and Coatings Physics (PLASM), Linköping University , 581 83 Linköping, Sweden
| | - Manuel Macias-Montero
- Nanotechnology and Integrated Bioengineering Centre (NIBEC), University of Ulster , Newtownabbey, BT37 0QB, Northern Ireland, U.K
| | - Paul Joseph
- Centre for Environmental Safety and Risk Engineering (CESARE), College of Engineering and Science, Victoria University , Room 4206, Level 2, Building 4 Hoppers Lane, Werribee Campus Victoria 3030, Melbourne, Australia
| | - Dorian Dixon
- Nanotechnology and Integrated Bioengineering Centre (NIBEC), University of Ulster , Newtownabbey, BT37 0QB, Northern Ireland, U.K
| | - Kostya Ostrikov
- School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology , Brisbane, Queensland 4000, Australia
- Joint CSIRO-QUT Sustainable Materials and Devices Laboratory, CSIRO , P.O. Box 218, Lindfield, New South Wales 2070, Australia
| | - Paul Maguire
- Nanotechnology and Integrated Bioengineering Centre (NIBEC), University of Ulster , Newtownabbey, BT37 0QB, Northern Ireland, U.K
| | - Davide Mariotti
- Nanotechnology and Integrated Bioengineering Centre (NIBEC), University of Ulster , Newtownabbey, BT37 0QB, Northern Ireland, U.K
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12
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Macias-Montero M, Askari S, Mitra S, Rocks C, Ni C, Svrcek V, Connor PA, Maguire P, Irvine JTS, Mariotti D. Energy band diagram of device-grade silicon nanocrystals. Nanoscale 2016; 8:6623-6628. [PMID: 26939617 DOI: 10.1039/c5nr07705b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Device grade silicon nanocrystals (NCs) are synthesized using an atmospheric-pressure plasma technique. The Si NCs have a small and well defined size of about 2.3 nm. The synthesis system allows for the direct creation of thin films, enabling a range of measurements to be performed and easy implementation of this material in different devices. The chemical stability of the Si NCs is evaluated, showing relatively long-term durability thanks to hydrogen surface terminations. Optical and electrical characterization techniques, including Kelvin probe, ultraviolet photoemission spectroscopy and Mott-Schottky analysis, are employed to determine the energy band diagram of the Si NCs.
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Affiliation(s)
- M Macias-Montero
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - S Askari
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - S Mitra
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - C Rocks
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - C Ni
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - V Svrcek
- Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8568, Japan
| | - P A Connor
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - P Maguire
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
| | - J T S Irvine
- School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - D Mariotti
- Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, BT37 0QB, UK.
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Sarkhail P, Mehran L, Askari S, Tahmasebinejad Z, Tohidi M, Azizi F. Maternal Thyroid Function and Autoimmunity in 3 Trimesters of Pregnancy and their Offspring's Thyroid Function. Horm Metab Res 2016; 48:20-6. [PMID: 26566101 DOI: 10.1055/s-0035-1555878] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This study was performed to evaluate maternal thyroid dysfunction and autoimmunity during pregnancy and its correlation with thyroid function of offspring. In this cohort study, Serum TT4, TT3, T3U, TSH, TPOAb, and TgAb were measured. Serum samples of 120 pregnant women were collected during 3 trimesters as well as in 57 cord bloods, 69 neonates, 34, 37, and 36 infants aged 2, 4, and 6 months. Repeated measure and Pearson correlation test were used to compare thyroid hormone values and to assess the correlations, respectively. Main outcomes were correlations between thyroid hormones and antibodies in mothers and offspring. An increasing trend for TT3 (p for trend < 000.1) and TSH (p for trend 0.01) was found over the course of gestation. Among 120 mothers, 10 (8%) had subclinical hyperthyroidism and 18 mothers (15%) showed subclinical hypothyroidism. We found one hypothyroid (0.8%) and 3 hyperthyroid (2.5%) mothers during pregnancy. Correlations among maternal thyroid hormones were found but not with auto-antibodies. A positive correlation between maternal thyroid auto-antibodies in all trimesters with cord blood and neonates was found. Cord blood TSH had a good correlation with maternal TSH, but only in the first trimester (r=0.29, p<0.05). A positive correlation between neonatal TSH and maternal TT4 was found only in the third trimester (r=0.25, p<0.05). Subclinical hypothyroidism was the most common thyroid dysfunction in the pregnant women studied. The association between maternal auto-antibodies and thyroid hormones of offspring was observed mostly in the neonatal period and became weaker after one month of age.
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Affiliation(s)
- P Sarkhail
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, I. R. Iran
| | - L Mehran
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, I. R. Iran
| | - S Askari
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, I. R. Iran
| | - Z Tahmasebinejad
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, I. R. Iran
| | - M Tohidi
- Prevention of Metabolic Disorders Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, I. R. Iran
| | - F Azizi
- Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, I. R. Iran
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Askari S, Svrcek V, Maguire P, Mariotti D. The Interplay of Quantum Confinement and Hydrogenation in Amorphous Silicon Quantum Dots. Adv Mater 2015; 27:8011-8016. [PMID: 26523743 PMCID: PMC4738462 DOI: 10.1002/adma.201503013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 08/19/2015] [Indexed: 05/30/2023]
Abstract
Hydrogenation in amorphous silicon quantum dots (QDs) has a dramatic impact on the corresponding optical properties and band energy structure, leading to a quantum-confined composite material with unique characteristics. The synthesis of a-Si:H QDs is demonstrated with an atmospheric-pressure plasma process, which allows for accurate control of a highly chemically reactive non-equilibrium environment with temperatures well below the crystallization temperature of Si QDs.
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Affiliation(s)
- Sadegh Askari
- Nanotechnology & Integrated Bio-Engineering Centre-NIBEC, Ulster University, Newtownabbey, BT37 0QB, UK
| | - Vladmir Svrcek
- Research Center for Photovoltaic Technologies, National Institute of Advanced Industrial Science and Technology-AIST, Central 2, Umezono 1-1-1, Tsukuba, 305-8568, Japan
| | - Paul Maguire
- Nanotechnology & Integrated Bio-Engineering Centre-NIBEC, Ulster University, Newtownabbey, BT37 0QB, UK
| | - Davide Mariotti
- Nanotechnology & Integrated Bio-Engineering Centre-NIBEC, Ulster University, Newtownabbey, BT37 0QB, UK
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15
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Askari S, Montazerin N, Zarandi MF. A clustering based forecasting algorithm for multivariable fuzzy time series using linear combinations of independent variables. Appl Soft Comput 2015. [DOI: 10.1016/j.asoc.2015.06.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Ghasemi Falavarjani K, Alemzadeh SA, Modarres M, Parvaresh MM, Hashemi M, Naseripour M, Nazari Khanamiri H, Askari S. Scleral buckling surgery for rhegmatogenous retinal detachment with subretinal proliferation. Eye (Lond) 2015; 29:509-14. [PMID: 25613841 DOI: 10.1038/eye.2014.341] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 12/19/2014] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To evaluate the outcome of scleral buckling surgery in patients with rhegmatogenous retinal detachment (RRD) with subretinal proliferation. METHODS In this retrospective study, a chart review of all patients with RRD associated with subretinal proliferation who were primarily treated with scleral buckling procedure, from April 2007 to April 2014, was undertaken. Main outcome measures were anatomical retinal reattachment and visual acuity. RESULTS Forty-four eyes of 43 patients including 24 males and 19 females with a mean age of 26.5±13.1 years were evaluated. Immediately after the surgery, retina was reattached in all eyes. However, five eyes (11.3%) needed additional surgery for retinal redetachment. Single surgery anatomical success rate was 88.7%. Four eyes (9.1%), needed pars plana vitrectomy for the treatment of redetachment associated with proliferative vitreoretinopathy and scleral buckle revision surgery was successfully performed in the other eye. Best corrected visual acuity improved from 1.5±0.9 logMAR before surgery to 1.1±0.7 logMAR after surgery (P<0.001). An improvement in BCVA of >2 lines was found in 23 eyes (52.2%) and worsening of best corrected visual acuity of >2 lines was observed in 2 eyes (4.5%). CONCLUSIONS Scleral buckling surgery is highly successful in eyes with RRD associated with subretinal proliferation.
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Affiliation(s)
- K Ghasemi Falavarjani
- Eye Research Center, Eye Department, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - S A Alemzadeh
- Medical Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - M Modarres
- Eye Research Center, Eye Department, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - M M Parvaresh
- Eye Research Center, Eye Department, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - M Hashemi
- Eye Research Center, Eye Department, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - M Naseripour
- Eye Research Center, Eye Department, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | | | - S Askari
- Medical Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
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Kamgar P, Agarwal A, Chao T, Askari S, Tan M, Honor R, Won DS. Step trajectory analysis of spinal cord injured rats trained with neuromuscular electrical stimulation coordinated with robotic treadmill training. Annu Int Conf IEEE Eng Med Biol Soc 2013; 2012:1864-7. [PMID: 23366276 DOI: 10.1109/embc.2012.6346315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Applying neuromuscular electrical stimulation (NMES) during treadmill training (TT) has been shown to improve functional outcomes, such as gait speed and walking distance, in spinal cord injury (SCI) patients. However, ways to improve this combined NMES+TT therapy have not been investigated. We have developed NMES system for a rodent model of SCI to investigate whether and how more precisely timing the stimulation to robotically assisted hindlimb position might achieve rehabilitation of independent stepping after SCI. In our therapy (NMES+RTT), rodent ankle flexor muscles are stimulated while the hindlimbs are robotically driven through pre-programmed trajectories during treadmill training. The objectives of the work presented here were to quantify changes in step trajectory resulting from our combined NMES+RTT therapy and compare those effects with those induced by robotic treadmill training (RTT) alone. Animals were spinally contused to model severe SCI, and either received 2 weeks of NMES+RTT followed by 2 weeks of RTT (n=6) or 2 weeks of RTT followed by 2 weeks of NMES+RTT (n=7). Changes in step trajectories after training were analyzed. According to a deviation measure we developed, the step trajectories improved after either NMES+RTT or RTT training but more closely matched the desired pre-programmed trajectories after NMES+RTT than after RTT only. The step trajectories are also more consistent, as indicated by a coefficient of variation measure, after training and more so after NMES+RTT than after RTT only. These preliminary results from our NMES+RTT vs. RTT study are consistent with the hypothesis that appropriately timing NMES with hindlimb movements during stepping is an effective therapy for restoring the ability to step after spinal cord injury.
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Affiliation(s)
- P Kamgar
- Electrical and Computer Engineering Department, California State University - Los Angeles, Los Angeles, CA 90032, USA.
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Khazan M, Hedayati M, Askari S, Azizi F. Adulteration of products sold as Chinese Herbal medicines for weight loss with thyroid hormones and PCP. J Herb Med 2013. [DOI: 10.1016/j.hermed.2012.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Askari S, Halladj R. Ultrasonic pretreatment for hydrothermal synthesis of SAPO-34 nanocrystals. Ultrason Sonochem 2012; 19:554-9. [PMID: 22000096 DOI: 10.1016/j.ultsonch.2011.09.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 09/11/2011] [Accepted: 09/21/2011] [Indexed: 05/06/2023]
Abstract
Synthesis of SAPO-34 nanocrystals which has been recently considered as a challenging task was successfully performed by sonochemical method using TEAOH as structure directing agent (SDA). The products were characterized by XRD, SEM, EDX, BET and TGA. The average crystal size of the final product prepared sonochemically is 50 nm that is much smaller than that of synthesized under hydrothermal condition and the morphology of the crystals changes from uniform spherical nanoparticles to spherical aggregates of cube type SAPO-34 crystals respectively. In the case of sample synthesized sonochemically with aid of hydrothermal condition, the surface area is significantly upper than that of obtained by the conventional static hydrothermal technology with almost the same crystallinity. SAPO-34 framework synthesized by just ultrasonic treatment is unstable and a significant part of SAPO-34 nanocrystals is transformed to the dense phase of AlPO(4) structure, i.e., Cristobalite. Contrary to hydrothermal method that at least 24h of the synthesis time is required to obtain fully crystalline SAPO-34, sonochemical-assisted hydrothermal synthesis of samples leads to form fully crystalline SAPO-34 crystals taking only 1.5h. In a sonochemical process, a huge density of energy for crystallization is provided by the collapse of bubbles which formed by ultrasonic waves. The fact that small SONO-SAPO-34 crystals could be prepared by the sonochemical method suggests a high nucleation density in the early stages of synthesis and slow crystal growth after nucleation.
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Affiliation(s)
- S Askari
- Faculty of Chemical Engineering, Amirkabir University of Technology, Tehran Polytechnic, PO Box 15875-4413, Hafez Ave, Tehran, Iran
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Askari S, Chao T, Conn L, Partida E, Lazzaretto T, See PA, Chow C, de Leon RD, Won DS. Effect of functional electrical stimulation (FES) combined with robotically assisted treadmill training on the EMG profile. Annu Int Conf IEEE Eng Med Biol Soc 2012; 2011:3043-6. [PMID: 22254981 DOI: 10.1109/iembs.2011.6090832] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Functional electrical stimulation (FES) is used to assist spinal cord injury patients during walking. However, FES has yet to be shown to have lasting effects on the underlying neurophysiology which lead to long-term rehabilitation. A new approach to FES has been developed by which stimulation is timed to robotically controlled movements in an attempt to promote long-term rehabilitation of walking. This approach was tested in a rodent model of spinal cord injury. Rats who received this FES therapy during a 2-week training period exhibited peak EMG activity during the appropriate phase of the gait cycle; whereas, rats who received stimulation which was randomly timed with respect to their motor activity exhibited no clear pattern in their EMG profile. These results from our newly developed FES system serve as a launching point for many future studies to test and understand the long-term effect of FES on spinal cord rehabilitation.
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Affiliation(s)
- S Askari
- Electrical and Computer Engineering Department, California State University – Los Angeles, Los Angeles, CA 90032, USA.
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22
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Warnock RA, Askari S, Butcher EC, von Andrian UH. Molecular mechanisms of lymphocyte homing to peripheral lymph nodes. J Exp Med 1998; 187:205-16. [PMID: 9432978 PMCID: PMC2212097 DOI: 10.1084/jem.187.2.205] [Citation(s) in RCA: 348] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/1997] [Revised: 11/19/1997] [Indexed: 02/05/2023] Open
Abstract
To characterize the adhesion cascade that directs lymphocyte homing to peripheral lymph nodes (PLNs), we investigated the molecular mechanisms of lymphocyte interactions with the microvasculature of subiliac lymph nodes. We found that endogenous white blood cells and adoptively transferred lymph node lymphocytes (LNCs) tethered and rolled in postcapillary high endothelial venules (HEVs) and to a lesser extent in collecting venules. Similarly, firm arrest occurred nearly exclusively in the paracortical HEVs. Endogenous polymorphonuclear (PMNs) and mononuclear leukocytes (MNLs) attached and rolled in HEVs at similar frequencies, but only MNLs arrested suggesting that the events downstream of primary rolling interactions critically determine the specificity of lymphocyte recruitment. Antibody inhibition studies revealed that L-selectin was responsible for attachment and rolling of LNCs, and that LFA-1 was essential for sticking. LFA-1-dependent arrest was also abolished by pertussis toxin, implicating a requirement for G alpha i--protein-linked signaling. alpha 4 integrins, which play a critical role in lymphocyte homing to Peyer's Patches, made no significant contribution to attachment, rolling, or sticking in resting PLNs. Velocity analysis of interacting LNCs revealed no detectable contribution by LFA-1 to rolling. Taken together, our results suggest that lymphocyte- HEV interactions within PLNs are almost exclusively initiated by L-selectin followed by a G protein-coupled lymphocyte-specific activation event and activation-induced engagement of LFA-1. These events constitute a unique adhesion cascade that dictates the specificity of lymphocyte homing to PLNs.
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Affiliation(s)
- R A Warnock
- Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford University, California 94305, USA
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Coxon A, Rieu P, Barkalow FJ, Askari S, Sharpe AH, von Andrian UH, Arnaout MA, Mayadas TN. A novel role for the beta 2 integrin CD11b/CD18 in neutrophil apoptosis: a homeostatic mechanism in inflammation. Immunity 1996; 5:653-66. [PMID: 8986723 DOI: 10.1016/s1074-7613(00)80278-2] [Citation(s) in RCA: 493] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In mice selectively deficient in CD11b/CD18, a beta 2 integrin, chemoattractant-induced leukocyte adhesion to microvascular endothelium in vivo was reduced. Paradoxically, thioglycollate-induced neutrophil accumulation in the peritoneal cavity was increased and was associated with a significant delay in apoptosis of extravasated cells. The extravasated cells had a near absence of neutrophil phagocytosis and a reduction in oxygen free radical generation, which may contribute to the observed defect in apoptosis. This is supported by our in vitro studies, in which phagocytosis of opsonized particles by human neutrophils rapidly induced apoptosis that could be blocked with CD11b/ CD18 antibodies. Reactive oxygen species are the intracellular link in this process: phagocytosis-induced apoptosis was blocked both in neutrophils treated with the flavoprotein inhibitor diphenylene iodonium and in neutrophils from patients with chronic granulomatous disease, which lack NADPH oxidase. Thus, CD11b/CD18 plays a novel and unsuspected homeostatic role in inflammation by accelerating the programmed elimination of extravasated neutrophils.
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Affiliation(s)
- A Coxon
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, USA
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Voss KF, Foster CM, Smilowitz L, Mihailovic D, Askari S, Srdanov G, Ni Z, Shi S, Heeger AJ, Wudl F. Substitution effects on bipolarons in alkoxy derivatives of poly(1,4-phenylene-vinylene). Phys Rev B Condens Matter 1991; 43:5109-5118. [PMID: 9997889 DOI: 10.1103/physrevb.43.5109] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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German DC, Dubach M, Askari S, Speciale SG, Bowden DM. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonian syndrome in Macaca fascicularis: which midbrain dopaminergic neurons are lost? Neuroscience 1988; 24:161-74. [PMID: 3259295 DOI: 10.1016/0306-4522(88)90320-x] [Citation(s) in RCA: 169] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces, in both human and non-human primates, a syndrome very similar to idiopathic Parkinson's disease. The syndrome is associated with degeneration of the dopamine-containing neurons in the substantia nigra, many of which project to the neostriatum. The purpose of the present study was to quantify the regional distribution of midbrain dopamine neurons remaining after MPTP administration to the monkey (Macaca fascicularis) and to develop alternative procedures for maintaining the normal nutrition in MPTP-treated animals. Three monkeys were treated with MPTP and three served as controls. Representative sections were examined from rostral to caudal through the midbrain dopamine cell nuclei and the location of every tyrosine hydroxylase-containing cell was entered into a computer. Midbrain dopamine neuronal cell loss ranged from 36-78%, being most extensive in the two monkeys which exhibited the most severe parkinsonian syndrome. The greatest cell loss (46-93%) occurred in the substantia nigra pars compacta, or nucleus A9, and the loss was primarily in the ventral portion of the nucleus. Contrary to most previous reports, however, there was also a loss of cells in the ventral tegmental area (28-57%) and ventral reticular formation (33-87%), corresponding to nuclei A10 and A8, respectively. Since neuroanatomical tracing studies have shown that the dorsal and lateral portions of the striatum (areas showing the greatest dopamine depletion after MPTP) receive input from cells in the ventral A9 and from cells in the A8 and A10 areas, the present data suggest that MPTP preferentially destroys dopamine cells that project to the striatum (i.e. the mesostriatal cells).
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Affiliation(s)
- D C German
- Department of Psychiatry, University of Texas Health Science Center, Dallas 75235
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Abbady MA, Askari S, Morgan M, Ternay AL, Galloy J, Watson WH. Structure and bonding in 9-hydroxy-1,4-dimethylthioxanthenium bis(carbomethoxy)methylide and related ylides. J Heterocycl Chem 1982. [DOI: 10.1002/jhet.5570190644] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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