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Halefoglu YZ, Souadi G, Ayvacikli M, Bulcar K, Topaksu M, Canimoglu A, Madkhali O, Karmouch R, Can N. Tb-doped MgAl 2O 4 phosphors: A study of structural and luminescence characteristics. Appl Radiat Isot 2024; 203:111101. [PMID: 37925901 DOI: 10.1016/j.apradiso.2023.111101] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 10/24/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
In the MgO-Al2O3 system, magnesium aluminate spinel (MgAl2O4) is a technologically significant compound due to its unique properties, including a high melting point, low thermal conductivity, excellent thermal shock resistance, chemical inertness, and robust mechanical strength. This compound has diverse applications in refractory materials, catalyst supports, moisture sensors, nuclear techniques, insulating materials, and even military applications. While rare-earth elements are commonly used as dopants in luminescent materials, limited research exists on doping of Tb3+ ions in magnesium aluminate. This study investigates the luminescence properties of Tb3+ doped synthesis magnesium aluminate materials, shedding light on this underexplored area. The combustion method is employed for synthesis, known for producing nano-sized powders with exceptional luminescent properties. Additionally, this study explores Sm3+ ion doping in magnesium aluminate materials and their luminescence properties. Using the combustion synthesis method, structural attributes of Tb3+-doped MgAl2O4 nanophosphors are meticulously examined. Through X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses, coupled with excitation and emission spectra, a comprehensive investigation of the luminescent provide behavior at room temperature is provided. The XRD data reveal Tb3+ doped MgAl2O4 phosphors exhibit a single phase with face centred cubic structure belonging to the Fd3m‾ space group, consistent with the standard JCPDS files (No. 21-1152). Excitation and emission spectra offer valuable insights into the energy transitions within the Tb3+-doped MgAl2O4 phosphors. Furthermore, the study explores the effects of varying Tb3+ ion concentrations on the luminescent properties, revealing an optimal doping concentration of 5 wt% Tb for maximizing emission intensity. Concentration quenching, primarily attributed to dipole-dipole (d-q) interactions, is observed at higher Sm3+ concentrations. In conclusion, this research enhances our understanding of rare-earth ion doping in luminescent materials and highlights the potential applications of Tb3+-doped MgAl2O4 nanophosphors, which offer promise for various technological applications, including lighting and displays.
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Affiliation(s)
- Y Z Halefoglu
- Department of Ceramic, Faculty of Fine Arts, Cukurova University, 01330, Adana, Turkiye
| | - G Souadi
- Physics Department, College of Science, Jazan University, P.O. Box 114, 45142, Jazan, Saudi Arabia
| | - M Ayvacikli
- Manisa Celal Bayar University, Hasan Ferdi Turgutlu Technology Faculty, Mechatronics Engineering, Turgutlu-Manisa, Turkiye
| | - K Bulcar
- Igdir University, Vocational School of Health Services, Karaagac Campus, 76000, Igdir, Turkiye
| | - M Topaksu
- Physics Department, Cukurova University, Arts-Sciences Faculty, 01330, Adana, Turkiye
| | - A Canimoglu
- Nigde Omer Halisdemir University, Faculty of Arts and Sciences, Physics Department, Nigde, Turkiye
| | - O Madkhali
- Physics Department, College of Science, Jazan University, P.O. Box 114, 45142, Jazan, Saudi Arabia
| | - R Karmouch
- Physics Department, College of Science, Jazan University, P.O. Box 114, 45142, Jazan, Saudi Arabia
| | - N Can
- Physics Department, College of Science, Jazan University, P.O. Box 114, 45142, Jazan, Saudi Arabia.
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Abstract
The pyridazine ring is endowed with unique physicochemical properties, characterized by weak basicity, a high dipole moment that subtends π-π stacking interactions and robust, dual hydrogen-bonding capacity that can be of importance in drug-target interactions. These properties contribute to unique applications in molecular recognition while the inherent polarity, low cytochrome P450 inhibitory effects and potential to reduce interaction of a molecule with the cardiac hERG potassium channel add additional value in drug discovery and development. The recent approvals of the gonadotropin-releasing hormone receptor antagonist relugolix (24) and the allosteric tyrosine kinase 2 inhibitor deucravacitinib (25) represent the first examples of FDA-approved drugs that incorporate a pyridazine ring. In this review, the properties of the pyridazine ring are summarized in comparison to the other azines and its potential in drug discovery is illustrated through vignettes that explore applications that take advantage of the inherent physicochemical properties as an approach to solving challenges associated with candidate optimization. Graphical Abstract
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Ji Y, Liang L, Bao X, Hou G. Recent progress in dipolar recoupling techniques under fast MAS in solid-state NMR spectroscopy. Solid State Nucl Magn Reson 2021; 112:101711. [PMID: 33508579 DOI: 10.1016/j.ssnmr.2020.101711] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 12/04/2020] [Accepted: 12/05/2020] [Indexed: 06/12/2023]
Abstract
With the recent advances in NMR hardware and probe design technology, magic-angle spinning (MAS) rates over 100 kHz are accessible now, even on commercial solid NMR probes. Under such fast MAS conditions, excellent spectral resolution has been achieved by efficient suppression of anisotropic interactions, which also opens an avenue to the proton-detected NMR experiments in solids. Numerous methods have been developed to take full advantage of fast MAS during the last decades. Among them, dipolar recoupling techniques under fast MAS play vital roles in the determination of the molecular structure and dynamics, and are also key elements in multi-dimensional correlation NMR experiments. Herein, we review the dipolar recoupling techniques, especially those developed in the past two decades for fast-to-ultrafast MAS conditions. A major focus for our discussion is the ratio of RF field strength (in frequency) to MAS frequency, ν1/νr, in different pulse sequences, which determines whether these dipolar recoupling techniques are suitable for NMR experiments under fast MAS conditions. Systematic comparisons are made among both heteronuclear and homonuclear dipolar recoupling schemes. In addition, the schemes developed specially for proton-detection NMR experiments under ultrafast MAS conditions are highlighted as well.
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Affiliation(s)
- Yi Ji
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lixin Liang
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinhe Bao
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China
| | - Guangjin Hou
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China.
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Abstract
This short review focuses on three aspects of rational drug design that we consider of utmost importance: the conformation of small molecules in solid form, the conformation of small molecules in solution and lesser studied interactions in protein-ligand complexes. Using examples from recent literature, we will illustrate these different aspects and how they have contributed to the discovery of potent modulators.
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Affiliation(s)
- Ashley Jarvis
- Evotec (U.K.) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire OX14 4RZ, United Kingdom
| | - Gilles Ouvry
- Evotec (U.K.) Ltd., 114 Innovation Drive, Milton Park, Abingdon, Oxfordshire OX14 4RZ, United Kingdom.
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Li Q, Wan X, Liu C, Fang L. Investigating the role of ion-pair strategy in regulating nicotine release from patch: Mechanistic insights based on intermolecular interaction and mobility of pressure sensitive adhesive. Eur J Pharm Sci 2018; 119:102-111. [PMID: 29627622 DOI: 10.1016/j.ejps.2018.04.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 03/15/2018] [Accepted: 04/03/2018] [Indexed: 11/19/2022]
Abstract
The aim of this study was to prepare a drug-in-adhesive patch of nicotine (NIC) and use ion-pair strategy to regulate drug delivery rate. Moreover, the mechanism of how ion-pair strategy regulated drug release was elucidated at molecular level. Formulation factors including pressure sensitive adhesives (PSAs), drug loading and counter ions (C4, C6, C8, C10, and C12) were screened. In vitro release experiment and in vitro transdermal experiment were conducted to determine the rate-limiting step in drug delivery process. FT-IR and molecular modeling were used to characterize the interaction between drug and PSA. Thermal analysis and rheology study were conducted to investigate the mobility variation of PSA. The optimized patch prepared with NIC-C8 had the transdermal profile fairly close to that of the commercial product (p > 0.05). The release rate constants (k) of NIC, NIC-C4 and NIC-C10 were 21.1, 14.4 and 32.4, respectively. Different release rates of NIC ion-pair complexes were attributed to the dual effect of ion-pair strategy on drug release. On one hand, ion-pair strategy enhanced the interaction between drug and PSA, which inhibited drug release. On the other hand, using ion-pair strategy improved the mobility of PSA, which facilitated drug release. Drug release behavior was determined by combined effect of two aspects above. These conclusions provided a new idea for us to regulate drug release behavior from patch.
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Affiliation(s)
- Qiaoyun Li
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Xiaocao Wan
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Chao Liu
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Liang Fang
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenyang, Liaoning 110016, China.
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Marsh D. Coherence transfer and electron T 1-, T 2-relaxation in nitroxide spin labels. J Magn Reson 2017; 277:86-94. [PMID: 28258025 DOI: 10.1016/j.jmr.2017.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 06/06/2023]
Abstract
Abragam's double-commutator spin operator method is used to analyse: 1) electron coherence transfer by intermolecular dipolar interaction between spin-label radicals, and 2) longitudinal and transverse electron spin relaxation by rotational modulation of the Zeeman and nitrogen-hyperfine anisotropies of isolated nitroxide spin labels. Results compatible with earlier treatments by Redfield theory are obtained without specifically evaluating matrix elements. Extension to single-transition operators for isolated nitroxides predicts electron coherence transfer by pseudosecular electron-nuclear dipolar interaction, in the absence of intermolecular dipolar coupling. This explains earlier experimental findings that coherence transfer (specifically dispersion-like distortion of the EPR absorption line shape) does not extrapolate to zero at low concentrations of nitroxide spin labels.
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Affiliation(s)
- Derek Marsh
- Max-Planck-Institut für biophysikalische Chemie, 37070 Göttingen, Germany; University of Southern Denmark, MEMPHYS-Centre for Biomembrane Physics, Campusvej 55, 5230 Odense M, Denmark.
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Xue M, Kitahara R, Yoshimura Y, Mulder FAA. Aberrant increase of NMR signal in hydrogen exchange experiments. Observation and explanation. Biochem Biophys Res Commun 2016; 478:1185-8. [PMID: 27544032 DOI: 10.1016/j.bbrc.2016.08.092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 08/15/2016] [Indexed: 12/14/2022]
Abstract
Hydrogen exchange (HX) NMR spectroscopy is widely used for monitoring structure, stability and dynamics of proteins at the level of individual residues. The stochastic replacement of protons by deuterons typically leads to an exponential decrease of the NMR signals. However, an unusual signal increase was observed in HX of several amides for T4 lysozyme L99A. This effect can be attributed to peak sharpening as a result of reduced dipolar relaxation from proximal amide protons that experience more rapid hydrogen/deuterium (H/D) exchange. The behavior was specifically observed at the termini of secondary structure elements, where large differences in protection against H/D exchange are observed. This effect is expected to be more widespread in NMR HX studies, and is important for the accurate determination of protection factors.
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Affiliation(s)
- Mengjun Xue
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark
| | - Ryo Kitahara
- College of Pharmaceutical Sciences, Ritsumeikan University, Shiga, Japan
| | - Yuichi Yoshimura
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark
| | - Frans A A Mulder
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark.
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