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Wang P, Li J, Ma Y, Jiang Z. Quantifying the Endogeneity in Online Donations. Entropy (Basel) 2021; 23:1667. [PMID: 34945973 DOI: 10.3390/e23121667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/09/2021] [Accepted: 12/09/2021] [Indexed: 11/17/2022]
Abstract
Charitable crowdfunding provides a new channel for people and families suffering from unforeseen events, such as accidents, severe illness, and so on, to seek help from the public. Thus, finding the key determinants which drive the fundraising process of crowdfunding campaigns is of great importance, especially for those suffering. With a unique data set containing 210,907 crowdfunding projects covering a period from October 2015 to June 2020, from a famous charitable crowdfunding platform, specifically Qingsong Chou, we will reveal how many online donations are due to endogeneity, referring to the positive feedback process of attracting more people to donate through broadcasting campaigns in social networks by donors. For this aim, we calibrate three different Hawkes processes to the event data of online donations for each crowdfunding campaign on each day, which allows us to estimate the branching ratio, a measure of endogeneity. It is found that the online fundraising process works in a sub-critical state and nearly 70-90% of the online donations are endogenous. Furthermore, even though the fundraising amount, number of donations, and number of donors decrease rapidly after the crowdfunding project is created, the measure of endogeneity remains stable during the entire lifetime of crowdfunding projects. Our results not only deepen our understanding of online fundraising dynamics but also provide a quantitative framework to disentangle the endogenous and exogenous dynamics in complex systems.
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Urbina Medina IA, Carneiro DD, Rocha S, Farias EE, Bredice FO, Palleschi V. Branching Ratio Method for Assessing Optically Thin Conditions in Laser-Induced Plasmas. Appl Spectrosc 2021; 75:774-780. [PMID: 33739164 DOI: 10.1177/00037028211006764] [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] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The branching ratio method is usually used to evaluate the optical thinness conditions in laser-generated plasmas, which are important for the application of analytical methods such calibration free laser induced breakdown spectroscopy (CF-LIBS). In this communication, we warn on the possibility that in some circumstances, the branching-ratio method might give results close to the one characterizing optically thin plasma conditions, even in the presence of a substantial self-absorption for the transitions considered.
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Affiliation(s)
| | - Deborah D Carneiro
- Universidad Federal de Roraima, Boa Vista, Brazil
- Centro Universitário Estácio da Amazônia, Boa Vista, Brazil
| | | | | | | | - Vincenzo Palleschi
- Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic, Compounds, Research Area of National Research Council, Pisa, Italy
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Reddy Prasad V, Seshadri M, Babu S, Ratnakaram YC. Concentration-dependent studies of Nd 3+ -doped zinc phosphate glasses for NIR photoluminescence at 1.05 μm. LUMINESCENCE 2017; 32:443-451. [PMID: 27546167 DOI: 10.1002/bio.3200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [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: 03/18/2016] [Revised: 06/12/2016] [Accepted: 07/08/2016] [Indexed: 11/10/2022]
Abstract
Nd3+ -doped lead-free zinc phosphate glasses with the chemical compositions (60-x) NH4 H2 PO4 + 20ZnO + 10BaF2 + 10NaF + xNd2 O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) were prepared using a melt quenching technique. Vibrational bands were assigned and clearly elucidated by Raman spectral profiles for all the glass samples. Judd-Ofelt (J-O) intensity parameters (Ωλ : λ = 2, 4, 6) were obtained from the spectral intensities of different absorption bands of Nd3+ ions. Radiative properties such as radiative transition probabilities (AR ), radiative lifetimes (τR ) and branching ratios (βR ) for different excited states were calculated using J-O parameters. The near infrared (NIR) photoluminescence spectra exhibited three emission bands (4 F3/2 level to 4 I13/2 , 4 I11/2 and 4 I9/2 states) for all the concentrations of Nd3+ ions. Various luminescence properties were studied by varying the Nd3+ concentration for the three spectral profiles. Fluorescence decay curves of the 4 F3/2 level were recorded. The energy transfer mechanism that leads to quenching of the 4 F3/2 state lifetimes was discussed at higher concentration of Nd3+ ions. These glasses are suggested as suitable hosts to produce efficient lasing action in NIR region at 1.05 μm.
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Affiliation(s)
- V Reddy Prasad
- Department of Physics, Sri Venkateswara University, Tirupati, India
| | - M Seshadri
- Department of Physics, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil
| | - S Babu
- Department of Physics, Sri Venkateswara University, Tirupati, India
| | - Y C Ratnakaram
- Department of Physics, Sri Venkateswara University, Tirupati, India
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Sumiya Y, Taketsugu T, Maeda S. Full rate constant matrix contraction method for obtaining branching ratio of unimolecular decomposition. J Comput Chem 2016; 38:101-109. [PMID: 27796079 DOI: 10.1002/jcc.24526] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [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: 08/25/2016] [Revised: 10/05/2016] [Accepted: 10/12/2016] [Indexed: 11/06/2022]
Abstract
The branching ratio of unimolecular decomposition can be evaluated by solving the rate equations. Recent advances in automated reaction path search methods have enabled efficient construction of the rate equations based on quantum chemical calculations. However, it is still difficult to solve the rate equations composed of hundreds or more elementary steps. This problem is especially serious when elementary steps that occur in highly different timescales coexist. In this article, we introduce an efficient approach to obtain the branching ratio from a given set of rate equations. It has been derived from a recently proposed rate constant matrix contraction (RCMC) method, and termed full-RCMC (f-RCMC). The f-RCMC gives the branching ratio without solving the rate equations. Its performance was tested numerically for unimolecular decomposition of C3 H5 and C4 H5 . Branching ratios obtained by the f-RCMC precisely reproduced the values obtained by numerically solving the rate equations. It took about 95 h to solve the rate equations of C4 H5 consisting of 234 elementary steps. In contrast, the f-RCMC gave the branching ratio in less than 1 s. The f-RCMC would thus be an efficient alternative of the conventional kinetic simulation approach. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Yosuke Sumiya
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita-ku, Sapporo, 060-8628, Japan
| | - Tetsuya Taketsugu
- Department of Chemistry, Faculty of Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan
| | - Satoshi Maeda
- Department of Chemistry, Faculty of Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan
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Bora DK, Cheng X, Kapilashrami M, Glans PA, Luo Y, Guo JH. Influence of crystal structure, ligand environment and morphology on Co L-edge XAS spectral characteristics in cobalt compounds. J Synchrotron Radiat 2015; 22:1450-8. [PMID: 26524310 DOI: 10.1107/s1600577515017178] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 09/14/2015] [Indexed: 05/07/2023]
Abstract
The electronic structure of a material plays an important role in its functionality for different applications which can be probed using synchrotron-based spectroscopy techniques. Here, various cobalt-based compounds, differing in crystal structure, ligands surrounding the central metal ion and morphology, have been studied by soft X-ray absorption spectroscopy (XAS) at the Co L-edge in order to measure the effect of these parameters on the electronic structure. A careful qualitative analysis of the spectral branching ratio and relative intensities of the L3 and L2 peaks provide useful insight into the electronic properties of compounds such as CoO/Co(OH)2, CoCl2.6H2O/CoF2.4H2O, CoCl2/CoF2, Co3O4 (bulk/nano/micro). For further detailed analysis of the XAS spectra, quantitative analysis has been performed by fitting the spectral profile with simulated spectra for a number of cobalt compounds using crystal field atomic multiplet calculations.
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Affiliation(s)
- D K Bora
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - X Cheng
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - M Kapilashrami
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - P A Glans
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Y Luo
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, People's Republic of China
| | - J-H Guo
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
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Abstract
A quantum-mechanical study of the predissociation of H2O(+) (B̃ (2)B2) is carried out by using wave packet propagations on ab initio potential energy surfaces connected by nonadiabatic couplings. The simulations show that within the first 30 fs 80% of the initial wave packet is transferred from the B̃ (2)B2 to the à (2)A1 electronic state through a conical intersection. A much slower transfer (in the ps time scale) from the à (2)A1 to the X̃ (2)B1 state due to a Renner-Teller coupling determines the fragmentation branching ratios, which are in accordance with the experimental measurements.
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Affiliation(s)
- Jaime Suárez
- Laboratorio Asociado al CIEMAT de Física Atómica y Molecular en Plasmas de Fusión, Departamento de Química, módulo 13, Universidad Autónoma de Madrid, Avenida Francisco Tomás y Valiente, 7, 28049 Madrid, Spain
| | - L Méndez
- Laboratorio Asociado al CIEMAT de Física Atómica y Molecular en Plasmas de Fusión, Departamento de Química, módulo 13, Universidad Autónoma de Madrid, Avenida Francisco Tomás y Valiente, 7, 28049 Madrid, Spain
| | - I Rabadán
- Laboratorio Asociado al CIEMAT de Física Atómica y Molecular en Plasmas de Fusión, Departamento de Química, módulo 13, Universidad Autónoma de Madrid, Avenida Francisco Tomás y Valiente, 7, 28049 Madrid, Spain
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Prozument K, Suleimanov YV, Buesser B, Oldham JM, Green WH, Suits AG, Field RW. A Signature of Roaming Dynamics in the Thermal Decomposition of Ethyl Nitrite: Chirped-Pulse Rotational Spectroscopy and Kinetic Modeling. J Phys Chem Lett 2014; 5:3641-3648. [PMID: 26278732 DOI: 10.1021/jz501758p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chirped-pulse (CP) Fourier transform rotational spectroscopy is uniquely suited for near-universal quantitative detection and structural characterization of mixtures that contain multiple molecular and radical species. In this work, we employ CP spectroscopy to measure product branching and extract information about the reaction mechanism, guided by kinetic modeling. Pyrolysis of ethyl nitrite, CH3CH2ONO, is studied in a Chen type flash pyrolysis reactor at temperatures of 1000-1800 K. The branching between HNO, CH2O, and CH3CHO products is measured and compared to the kinetic models generated by the Reaction Mechanism Generator software. We find that roaming CH3CH2ONO → CH3CHO + HNO plays an important role in the thermal decomposition of ethyl nitrite, with its rate, at 1000 K, comparable to that of the radical elimination channel CH3CH2ONO → CH3CH2O + NO. HNO is a signature of roaming in this system.
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Affiliation(s)
| | | | - Beat Buesser
- §IBM Research, Smarter Cities Technology Centre, Dublin 15, Ireland
| | - James M Oldham
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | | | - Arthur G Suits
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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An H, Baeck KK. Branching Ratio between Proton Transfer and Electron Transfer Channels of a Bidirectional Proton-Coupled Electron Transfer. J Phys Chem Lett 2014; 5:1307-1311. [PMID: 26269972 DOI: 10.1021/jz500396r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Rigorous quantum dynamical study of concerted proton-coupled electron transfer (PCET) on the time scale of a few femtoseconds (fs) has been rarely reported. Herein, a time-dependent quantum wavepacket propagation method was applied to the dynamics of the charge-transfer excited electronic state of FHCl corresponding to F(+)HCl(-). The dynamics corresponds to a bidirectional PCET with two dissociation channels: the electron transfer (ET, generating FH+Cl) and proton transfer (PT, generating F+HCl) paths. The calculated branching ratio (Cl/F), 0.78, implies a surprising fact: PT prevails over ET. A detailed analysis of the proton movement and electron readjustment suggests that the proton movement starts ∼3 fs earlier than the electron movement, and the electron readjustment is triggered by the initial movement of the proton. The branching ratio drastically inverts to 1.24 because of a reduced nonadiabatic effect in the isotope-substituted system, FDCl.
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Affiliation(s)
- Heesun An
- Department of Chemistry, Gangneung-Wonju National University, Gangneung, Gangwondo, 210-702, Korea
| | - Kyoung Koo Baeck
- Department of Chemistry, Gangneung-Wonju National University, Gangneung, Gangwondo, 210-702, Korea
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Posṕišil S, Bečvář F, Granja Bustamante C, Kubašta J, Telezhnikov SA. Secondary γ Transitions in (159) Gd After Neutron Capture at Isolated Resonances. J Res Natl Inst Stand Technol 2000; 105:173-176. [PMID: 27551604 PMCID: PMC4878354 DOI: 10.6028/jres.105.024] [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] [Figures] [Subscribe] [Scholar Register] [Accepted: 07/22/1999] [Indexed: 06/06/2023]
Abstract
The (158)Gd(n,γ)(159)Gd reaction was studied at 12 isolated neutron resonances by the TOF method at the IBR-30 Fast Pulse Reactor at JINR Dubna. Totally 15 secondary γ transitions in (159)Gd were recorded in the range from 450 keV to 750 keV. Of these, six previously unseen transitions were placed on the established (159)Gd level scheme. The depopulation of strongly populated levels at 507.7 keV and 558.2 keV (the head and the first excited members of band 1/2(-) [521]) was observed for the first time. It was shown that the observed 507.7 keV γ line, masked by the annihilation peak, originates from an unresolved doublet of transitions from the 507.7 keV level to the ground state and from the 558.2 keV level to the level at 50.7 keV. The 507.7 keV level decays exclusively to the ground state, while the 558.2 keV level decays via two transitions with a branching ratio that agrees well with the prediction according to Alaga's rule.
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Affiliation(s)
- S Posṕišil
- Department of Physics, Faculty of Nuclear Sciences and Physical Engineering Czech Technical University, Brehova 7, 115 19 Prague 1, Czech Republic
| | - F Bečvář
- Department of Low Temperature Physics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic
| | - C Granja Bustamante
- Department of Physics, Faculty of Nuclear Sciences and Physical Engineering Czech Technical University, Brehova 7, 115 19 Prague 1, Czech Republic
| | - J Kubašta
- Department of Physics, Faculty of Nuclear Sciences and Physical Engineering Czech Technical University, Brehova 7, 115 19 Prague 1, Czech Republic
| | - S A Telezhnikov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141 980 Dubna, Russia
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