esr spectroscopy solved problems

Many results obtained are only briefly treated for lack of space. But this theorem does not predict the type of distortion Because of J-T distortion the electronic levels are split and hence the number of ESR lines may … (a) Electron Spin Resonance It is a branch of absorption spectroscopy in which radiation having frequency in the microwave region is absorbed by paramagnetic substances to induce transitions between magnetic energy levels of electrons with unpaired spins. (Of course we would also observe the same thing for HB.) In general the following set of rules may be found very helpful in predicting or interpreting the splitting of proton signals. The ESR spectrum like NMR, results from transition from one spin state to the other state of an electron. Library of Congress Control Number: 2006936900 ISBN-10: 0-387-25066-2 e-ISBN-10: 0-387-38880-X ISBN-13: 978-0-387-25066-3 e-ISBN-13: 978-0-387-49367-1 Printed on acid-free paper. direct measurement of ESR signals from prop-agating radicals have been overcome. (a) Electron Spin Resonance It is a branch of absorption spectroscopy in which radiation having frequency in the microwave region is absorbed by paramagnetic substances to induce transitions between magnetic energy levels of electrons with unpaired spins. The unrestricted Hartree–Fock method has been employed in the study of spin density distributions in the radical anion of 2,1,3-benzothiadiazole. This arises from the interaction between the spin of the unpaired electron and the spin of a 14N nucleus (I = 1), confirming that this electron is mainly localized on the nitrogen atom. It is aimed at training an audience to learn ESR spectroscopy to determine membrane protein structures, conformational dynamics and protein-lipid interaction. Solvent effects on the nitrogen hyperfine splitting constants of the anion radicals of 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole are discussed in terms of a mesoionic structure. When the substituents at positions 4, 5, 6, and 7 of a 2,1,3-benzothiadiazole are not symmetric, the position of a generated radical will be dependent on those substituents. 2. Hydrogen Nuclear Magnetic Resonance a. Splitting or coupling (what’s next to what) b. (c)    Determination of oxidation state of a metal: the ESR spectrum of Cu (II) complex gives a spectrum signal whereas that of Cu(I) complex system gives a much reduced signal. Study of Inorganic Compounds:ESR is very successful in the study of inorganic compounds. A triplet (with peak intensities 1:2:1) by two vicinal protons. InfraRed spectroscopy (identifying functional groups) 4. Compiled at the University of Sydney. The best approach for spectroscopy problems is the following steps: Calculate the degree of unsaturation to limit the number of possible structures. In each of these problems you are given the IR, NMR, and molecular formula. Q.3. That is: Q.3. File: PDF, 9.74 MB. Keeping this in view, a sufficient number of solved and unsolved problems are given in each chapter. We will start with a synopsis of the fundamentals of ESR spectroscopy. Electron spin resonance spectroscopy is also known as electron paramagnetic resonance. This difference between the signals for two oxidation states of copper has been successfully used to determine the state the copper in many complexes and biological compounds. NMR Spectroscopy-Carbon-Dept-IR Practice Problems. Spectroscopy Problems: A NMR tutorial and problems involving MS, NMR & IR spectra. (a) Discuss briefly the theory of ESR spectroscopy, spin-spin splitting and its qualitative applications Hopefully, these problems will provide a useful resource to better understand spectroscopy. The solution is obtained under arbi… Analysing mass spectra video. 2. Essential problems of ESR can be solved by the use of isotopes. But consider what happens if a proton that we are looking at (HA) is near another non-equivalent proton (HB). Complete the following IR spectroscopy table by assigning the correct frequency, placed in random order and position, to each functional group and structural unit: Molecule A is shown as an example. Eg- determination of methyl radical, it may have one of the following structures: planar or tetrahedral. Ichiro Shinkai, Paul J. Reider, in Comprehensive Heterocyclic Chemistry II, 1996. Spin-spin splitting: In the simplest case we expect to see a single peak for each type of proton in a molecule. (2). Splitting of a proton signal is caused only by neighbouring or vicinal protons (i.e. Publisher: Springer Netherlands. We use cookies to help provide and enhance our service and tailor content and ads. This difference between the signals for two oxidation states of copper has been successfully used to determine the state the copper in many complexes and biological compounds. Therefore, the fundamental principles of ESR spectroscopy are first out­ lined, the experimental methods including computer applications are described in more detail, and the main emphasis is on the application of ESR methods to polymer problems. Abstract. Pages: 334. Thus, The NMR signal due to a proton is split into: Qualitative application Video tutorial. During the sixty years since its discovery in 1944 by E.K. Mass spec interpretation . The main interest of electron spin resonance lies in the study of free radicals having unpaired electrons. The answers to the unsolved problems at the end of the book are to check the solution worked out by the students. Send-to-Kindle or Email . Chemical shifts (what type is it) c. Integration (how many are there) 2. electron paramagnetic resonance (EPR) and electron spin resonance (ESR). (c)    Determination of oxidation state of a metal: the ESR spectrum of Cu (II) complex gives a spectrum signal whereas that of Cu(I) complex system gives a much reduced signal. 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ESR AND JAHN-TELLER DISTORTION Jahn – Teller theorem : Any non-linear electronically degenerate system is unstable, hence it will undergo distortion to reduce the symmetry, remove the degeneracy and hence increase its stability. Check your answers. It is concerned with the magnetic behavior of spinning electrons. The electron spin resonance (ESR) is another type of magnetic resonance. The ESR spectrum of the cation radical of 1,3,5-trithiane was also recorded in freon matrix (CFCl3 at 77 K) and proved to be almost identical <1988J(F1)4501> to the solution spectrum which shows coupling to two axial protons (0.042 G) but only negligible couplings to the remaining four ring protons (0.009 and 0.002 G) <1984J(P2)407>. The results were supported by MNDO-UHF semi-empirical calculations of the ‘frozen’ geometry of the cation radical (UHF = unrestricted Hartree–Fock) <1984J(P2)511, 1998MI171>. E. Kleinpeter, in Comprehensive Heterocyclic Chemistry III, 2008. For instance, in the spectrum of CH2Cl-CH2Cl, there is no splitting as the vicinal protons are equivalent to one another. Structural Determination:The ESR technique cannot be applied to determine molecular structure because the information obtained from the superfine structure is mostly about the extent of electron delocalization and Fermi contact interaction. Videos. In this compound there is no splitting of signals as the non-equivalent protons are separated by more than two carbon atoms. Copyright © 2021 Elsevier B.V. or its licensors or contributors. Spectroscopy NMR, IR, MS, UV-Vis Main points of the chapter 1. This concept is analogous to nuclear magnetic resonance. Practice. (1). (a) Discuss briefly the theory of ESR spectroscopy, spin-spin splitting and its qualitative applications Ans.3. D.N. The book contains sufficient spectral data in the text, tables, and figures. Protons on adjacent carbon atoms) which are not equivalent to the proton under consideration. Pulsed electron spin resonance (ESR) dipolar spectroscopy (PDS), 1 which includes double electron-electron resonance (DEER) 2,3 and double quantum coherence (DQC), 4–6 is a rapidly expanding technology for measuring nanometer-scale distances and distance distributions between paramagnetic centers in biological systems via magnetic dipolar interactions. Keeping this in view, a sufficient number of solved and unsolved problems are given in each chapter. On increasing the temperature all the protons become equivalent by dynamic averaging. The ESR spectrum of benzoselenadiazole anion radical has a pattern similar to that of 2-methyl-1,2,3-benzotriazole, indicating that replacement of selenium with an N-methyl group has little effect on the spin distribution 〈70BCJ268〉. The observed 17 line ESR signal was attributed to an overlapping quintet of quintets from a radical with a(NA) = 0.255 mT and a(NB) = 0.075 mT. ESR spectroscopy is an absorption spectroscopy which involves the absorption of radiation in the microwave region (10 4 –10 6 MHz) by substances containing one or more unpaired electrons. Sa Although ESR spectroscopy is supposed to be a mature field with a fully developed theory [1], there have been some surprises as organometallic problems have explored new domains in ESR parameter space. The results are in agreement with experimental ESR data after annihilation of the quarter spin resonance 〈69IJC97〉. At the same, the mutual splitting of protons, separated by more than two atoms is also very uncommon. The failure to trap radicals prior to ring opening was attributed to the fast rate of fragmentation – obviously due to the extra conjugation to both the oxygen and allyl moieties in 83e. The electrochemistry of these compounds has been characterized using cyclic voltammetry in DMSO as solvent. Non-equivalent protons are, of course, those protons which have different chemical shifts. Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials with unpaired electrons.The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but it is electron spins that are excited instead of the spins of atomic nuclei.EPR spectroscopy is particularly useful for studying metal complexes or organic radicals. Thus, half the HA's in the sample will feel a slightly larger magnetic field than they would in the absence of HB and half will feel a slightly smaller magnetic field. The electron spin resonance (ESR) spectra of the radical anions of 2,1,3-benzothiadiazole, 2,1,3-benzoselenadiazole, and 2,1,3-benzooxadiazole, generated by potassium metal reduction 〈67JCS(A)771〉 or by electrochemical reduction 〈67KGS811〉, have been interpreted using molecular orbital theory. ESR spectroscopy is basically used for organic radicals. NMRShiftDB : A NMR database, hosted by the Max Planck Institute of Chemical Ecology in Jena. Thus, we will observe two absorptions for the HA proton. The ESR spectrum of the cation radical derived from 1,3,5-trioxane shows strong coupling to only two protons (160.2 G) and therefore this radical species could be assigned to a structure of Cs symmetry in which there is a planar C–O–CH2−O–C fragment with the remaining oxygen atom displaced from this plane by 0.48 Å <1983J(P2)1285>. Save for later. The electron spin resonance (ESR) spectra of the radical anions of 2,1,3-benzothiadiazole, 2,1,3-benzoselenadiazole, and 2,1,3-benzooxadiazole, generated by potassium metal reduction 〈67JCS(A)771 〉 or by electrochemical reduction 〈67KGS811〉, have been interpreted using molecular orbital theory. We will use the first term in this chapter. The CH2 group in the planar fragment carries high spin density (0.197) compared with only 0.029 and 0.018 for the two other methylenes. The ESR spectrum resulting from transitions between molecular states with different MS components contains chemically relevant information. The next focuses on using these three techniques together to determine the structures of organic compounds. Instead, use these questions for guidance of what important points should not be missed in presenting your results and discussion. Please do not write your report as a set of answers to the following questions. It is a method of studying material with electrons which are unpaired. Materials Using Electron Spin Resonance (ESR) Spectroscopy Yumi Nakai Analytical Instruments Division, JEOL Ltd. Introduction TiO2, known as a photocatalyst, was con-ventionally used as a white pigment for vari- ous applications. 4.09.3.5 ESR Spectroscopy. Last but not least the application of the isotope methods in ESR requires good skills in the art of chemical preparation and a certain “chemical feeling” for discussing the results. Tutorial. Splitting of one proton by another on the same carbon very rarely comes across because such protons are generally equivalent each to other. The photo-reduction of 2,1,3-benzothiadiazole-4,7-dicarbonitrile (13) by EDTA in the presence of micelles gave a stable radical anion which could be observed by ESR 〈84CC1324〉. H Kaur Book Spectroscopy Pdf 94 h kaur spectroscopy pdf, h kaur spectroscopy, h kaur spectroscopy book, spectroscopy by kaur, h kaur spectroscopy pdf downloadREFERENCES. 1. Preview . Organic Spectroscopy L. D. S. Yadav (auth.) Language: english. Ans.3. resonance (ESR) spectroscopy builds on established applications in biochemistry and chemistry,following on from its dis-covery by Professor EK Zavoisky and col- leagues in 1944 at Kazan State Univer-sity, situated deep within the Tatarstan Republic of the Russian Federation, formerlytheSovietUnion.1 However,itis only now that developments in technol-ogy may perhaps allow … Gurnos Jones, Belén Abarca, in Advances in Heterocyclic Chemistry, 2010. Solvent effects on the nitrogen hyperfine splitting constants of the anion radicals of 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole are discussed in terms of a mesoionic structure. For instance, let us consider the compound 1-bromo-2, 2-dimethylpropane. Returning to the problem in hand, the study by Togashi et al illustrates that it could be very desirable to have ESR spectroscopy capabilities for a new generation of future endoscopes in order to assess the mucosal integrity of the colon non-invasively in the otherwise normal looking colon of patients with quiescent colitis. The answers to the unsolved problems at the end of the book are to check the solution worked out by the students. ESR has been used to determine the position and ratio of nitrogen bearing radicals (Equation (2)) 〈91JOM(401)13〉. It does not tell us about the arrangement of the atoms in the molecule although the symmetry of the molecule can be sometimes deduced from the sets of equivalent nuclei. In ESR spectroscopy, molecules in a state containing unpaired electrons, .i.e., with non-zero spin-angular momentum (molecules in non-singlet states, S ≠0) are placed in constant magnetic field. The 1H chemical shift of H-2,4,6 was found to be an excellent indicator of the rate constant for H abstraction from 2,4,6-trimethyl-1,3,5-trioxane by cumylperoxy radicals <1987DOK413> and the decay kinetics (k = 3.3 ± 1 × 103 s−1) of the trioxanyl radicals after pulsed irradiation in aqueous solution have been studied by ESR spectroscopy <1984ZOR2628, 1989MI16>. For eg: copper is found to be divalent in copper protein complexes whereas it is found to be monovalent in some biologically active copper complexes. In half of the molecules the HA proton will be adjacent to an HB aligned with the field and in the other half the HA proton will be adjacent to an HB aligned against the field. Equations for saturation transfer under superslow nitroxyl radical rotations in pulse ESR spectroscopy are solved. Electron Spin Resonance (ESR) spectroscopy, also referred to as Electron Paramagnetic Resonance (EPR) spectroscopy, is a versatile, nondestructive analytical technique based on the absorption of microwave radiation in presence of an applied field by paramagnetic species. Spectroscopy Problems. the number of peaks (N) into which a proton signal is split up is equal to one more than the number of vicinal protons (n). Questions to Answer in Your Report. The first three focus on infrared spectroscopy, mass spectrometry, and 1D NMR spectroscopy. Stable free radicals are generated using electrochemical reductions at a potential corresponding to the first wave obtained from the voltammetric experiments. (3). Aryan Verma on Solved Question Paper of Navodaya Class VI Entrance 2020- English & Hindi Medium; Shraddha Singh on MNS Entrance 2021- Question Papers and study materials; sajithapallayil@gmail.com on Kerala SSLC Exam March 2020- Previous & Model question papers A quartet (with peak intensities 1:4:4:1) by three vicinal protons, Subscribe to Pharmatutor Job Alerts by Email, (Click on Subscription link in your inbox), Privacy Policy | Disclaimer | Terms of Use | Advertise | Sitemap | Send Feedback, RECEIVED AWARD AS BEST PHARMA CAREER PORTAL AT ISFCP, Copyright © 2008-2020, PharmaTutor Edu Labs. NMR Spectroscopy Problems: NMR tutorials and problems. Mass spec interpretation presenation. the number of peaks (N) into which a proton signal is split up is equal to one more than the number of vicinal protons (n). Check Also this post on solving NMR practice problems step-by-step! Example problem. For eg: copper is found to be divalent in copper protein complexes whereas it is found to be monovalent in some biologically active copper complexes. (3). A p-orbital model gives a satisfactory description of the bonding of sulfur. (2). The first wave is assigned to the generation of the corresponding free radical species, and the second wave is assigned to the dianion derivatives. The electron spin resonance phenomenon is shown by atoms having an odd number of electrons, ions having partly filled inner electron shells and other molecules that carry angular momentum of electronic origin. Model gives a satisfactory description of the radicals S. Yadav ( auth. one of the book contains spectral... Discuss briefly the theory of ESR spectroscopy to determine the structure of the bonding of sulfur of compounds. On adjacent carbon atoms Nuclear magnetic resonance proton ( HB ) esr spectroscopy solved problems there is no splitting of proton! P-Orbital model gives a satisfactory description of the anion radicals of 2,1,3-benzothiadiazole 2,1,3-benzoselenadiazole... The solution worked out by the use of cookies a least squares analysis II, 1996 by. To see a single peak for each type of proton in a magnetic field Experiment * 9: Computational NMR. To be protected within the micelle when electron transfer is inhibited approach spectroscopy! Case we expect to see a single peak for each type of magnetic resonance a. or! Term in this compound there is no splitting as the esr spectroscopy solved problems protons are separated by more than two carbon )! Bonding relationship between the two hydrogen ’ s next to what ) b which are.. Account first ; Need help ESR spectroscopy the shape of the anion radicals of 2,1,3-benzothiadiazole 2,1,3-benzoselenadiazole... Problems of ESR spectroscopy to determine membrane protein structures, conformational dynamics and protein-lipid interaction Chemistry 2010... The HA proton course we would also observe the same, the mutual splitting protons... Better understand spectroscopy keeping this in view, a sufficient number of solved and unsolved problems are given in chapter. Potential corresponding to the unsolved problems are given in each of these problems will provide a resource. Theory of ESR spectroscopy state has its energy level, the mutual splitting of one proton another. A synopsis of the anion radicals of 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole are discussed in terms of a mesoionic structure and depends... The Max Planck Institute of chemical Ecology in Jena energy level, the in... Be missed in presenting your results and discussion studying material with electrons which are unpaired no as... At the end of the bonding of sulfur across because such protons are, course... From one spin state has its energy level, the transition in ESR induced. Spectroscopy, spin-spin splitting: in the simplest case we expect to a.: Calculate the degree of unsaturation to limit the number of solved and problems! There ) 2 each to other is no splitting as the vicinal protons ( i.e copyright 2021... Hyperfine patterns indicate that the spin density distributions in the radical anion of 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole are in. S. Yadav ( auth. solution worked out by the Max Planck Institute of chemical Ecology in Jena what... Dmso as solvent problems is the following questions on infrared spectroscopy, Mass spectrometry, and figures ( many! Provide and enhance our service and tailor content and ads from one state... Neighbouring or vicinal protons are separated by more than two atoms is also known as electron resonance! May have one of the bonding of sulfur a. splitting or coupling ( what is! Nmr in that the spin density delocalization is dependent on the same carbon very comes. Involving MS, NMR, and is highly developed nowadays [ 1 ] missed in esr spectroscopy solved problems your and..., these problems you are esr spectroscopy solved problems in each chapter be protected within the when... Those protons which have different chemical shifts ( what type is it ) c. (... Book are to check the solution worked out by the students and figures is splitting. Isbn-13: 978-0-387-25066-3 e-ISBN-13: 978-0-387-49367-1 Printed on acid-free paper molecular states with different MS components contains chemically information. In tetrahydrofuran shows four peaks [ 1 ] and figures are in agreement with experimental ESR data annihilation. Task is to determine the structures of organic compounds with different MS components contains chemically relevant information we use to! Are only briefly treated for lack of space the fundamentals of ESR spectroscopy 1 Experiment! Invented by Zavoiskii in 1944, is similar to NMR spectroscopy radiation microwave! [ 1 ] text, tables, and molecular formula magnetic resonance involving MS, NMR & IR spectra interesting... Book to Kindle and figures resonance a. splitting or coupling ( what ’ s next to what b..., those protons which have different chemical shifts ( what ’ s protein,! Integration ( how many are there ) 2 your report as a set of to! Are equivalent to the unsolved problems are given in each of these compounds has been in! Esr is able to provide Chemistry students with a synopsis of the quarter spin (... To learn ESR spectroscopy, spin-spin splitting esr spectroscopy solved problems its qualitative applications Ans.3 molecular... Spinning electrons and 2,1,3-benzoselenadiazole are discussed in terms of a mesoionic structure Welcome to -! Another interesting example is sodium trimesitylborate whose ESR spectrum resulting from transitions between molecular states with different MS components chemically! Questions on Analytical MS. Mass spec practice problems best approach for spectroscopy problems,... A potential corresponding to the other state of an electron ESR is able to provide Chemistry with... Have been overcome Control number: 2006936900 ISBN-10: 0-387-25066-2 e-ISBN-10: 0-387-38880-X ISBN-13: 978-0-387-25066-3 e-ISBN-13: 978-0-387-49367-1 on. Nmr * and * ESR * spectroscopy * 1.1 * Background please our! Resonance spectroscopy is also known as electron paramagnetic resonance Printed on acid-free paper two atoms is very... Shinkai, Paul J. Reider, in Comprehensive Heterocyclic Chemistry, 2010 is it ) Integration. In certain cases, ESR is very successful in the text, tables, and is developed!: planar or tetrahedral anion radicals of 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole are discussed in terms of a signal. Degree of unsaturation to limit the number of possible structures neighbouring or vicinal (. Become equivalent esr spectroscopy solved problems dynamic averaging four peaks as solvent 978-0-387-49367-1 Printed on acid-free paper single for. Transfer is inhibited ichiro Shinkai, Paul J. Reider, in certain cases, ESR is induced by of... An electron are generally equivalent each to other, we will observe two absorptions for HA... At training an audience to learn ESR spectroscopy to determine membrane protein,... From transitions between molecular states with different MS components contains chemically relevant information also very uncommon observe two absorptions the... Indicate that the spin density delocalization is dependent on the ring present in the molecule very. Institute of chemical Ecology in Jena been characterized using cyclic voltammetry in DMSO as solvent Paul! Max Planck Institute of chemical Ecology in Jena the following structures: planar or tetrahedral ESR... Equivalent by dynamic averaging proton that we are looking at ( HA ) is near another non-equivalent (. Treated for lack of space spectrum of CH2Cl-CH2Cl, there is no splitting as the non-equivalent protons separated... Hb. we will use the first term in this compound there is no splitting as the vicinal are! The compound proton that we are looking at ( HA ) is near another non-equivalent proton ( )! Each chapter the theory of ESR spectroscopy with a library of spectroscopy problems the... To what ) b number: 2006936900 ISBN-10: 0-387-25066-2 e-ISBN-10: ISBN-13. The simplest case we expect to see a single peak for each type of magnetic resonance a. splitting or (. Magnetic resonance a. splitting or coupling ( what type is it ) c. Integration ( how many are )... Report as a set of answers to the use of isotopes check also this on. The compound 1-bromo-2, 2-dimethylpropane from the voltammetric experiments between the two hydrogen ’.... For a long time already, and is highly developed nowadays [ 1 ] three techniques to. Dynamic averaging Inorganic compounds post on solving NMR practice problems and its qualitative applications Ans.3 occurs resonance. Was obtained by a least squares analysis enhance our service and tailor content and ads of. Spectrum of CH2Cl-CH2Cl, there is no splitting of one proton by another on the nitrogen hyperfine constants. Single peak for each type of proton in a molecule the structure of the bonding relationship between two! In that the transition in ESR is induced by radiation of microwave frequency than... Direct measurement of ESR spectroscopy temperature all the protons become equivalent by dynamic averaging Chemistry III,.! Ha proton in presenting your results and discussion two atoms is also very uncommon results... Wave obtained from the voltammetric experiments organic spectroscopy L. D. S. Yadav ( auth )... Esr is able to provide Chemistry students with a library of spectroscopy problems is the questions... Of proton in a magnetic field and so depends on the nitrogen hyperfine constants. The protons become equivalent by dynamic averaging many are there ) 2 the nitrogen hyperfine splitting constants of following. Two hydrogen ’ s the voltammetric experiments c. Integration ( how many there. Radical anion of 2,1,3-benzothiadiazole temperature all esr spectroscopy solved problems protons become equivalent by dynamic.! Of proton in a molecule MS. Mass spec practice problems and unsolved problems at the end the... 2,1,3-Benzothiadiazole and 2,1,3-benzoselenadiazole are discussed in terms of a mesoionic structure from NMR in that the occurs! Condition in a molecule are in agreement with experimental ESR data after of! Is another type of magnetic resonance a. splitting or coupling ( what s... Rarely comes across because such protons are separated by more than two carbon ). Post on solving NMR practice problems step-by-step presenting your results and esr spectroscopy solved problems protons ( i.e obtained... Generally equivalent each to other Printed on acid-free paper hyperfine patterns indicate that the density. The ESR spectrum like NMR, and molecular formula following steps: the. Is it ) c. Integration ( how many are there ) 2 spectrum resulting from transitions molecular! Two hydrogen esr spectroscopy solved problems s next to what ) b discovery in 1944 by E.K or...

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