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Search for "equilibrium" in Full Text gives 643 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Polarity effects in 4-fluoro- and 4-(trifluoromethyl)prolines

  • Vladimir Kubyshkin

Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151

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  • , although the exact nature of this interaction (orbital or dipolar) is debatable [82]. Result of this effect though, is that the trans-fluoroproline shifts the equilibrium towards a higher abundance of the trans-amide, while cis-fluoroproline promotes the cis-amide (Figure 8). This was indeed found in the
  • influence onto the trans/cis ratio. In contrast, the gauche-effect in fluoroprolines causes a much stronger stabilization of the C4-conformations, as this propagates into stronger effects in the trans/cis equilibrium. In addition, there is a weak but systematic modulation in the trans/cis equilibrium caused
  • /cis equilibrium values (Ktrans/cis) were different in 5 compared to the non-fluorinated reference 7. Likewise, the trans/cis equilibrium in 3 is similar to the unsubstituted proline. Conversely, in compound 6, there was a higher content of the C4-endo conformation, a lower trans/cis equilibrium ratio
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Published 23 Jul 2020

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

  • Dalel El-Marrouki,
  • Sabrina Touchet,
  • Abderrahmen Abdelli,
  • Hédi M’Rabet,
  • Mohamed Lotfi Efrit and
  • Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

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  • leading to the formation of the indolone 7 starts with an imine formation between the secondary amine and the nonconjugated carbonyl from the 1,4-diketone. After an imine–enamine equilibrium, an intramolecular 1,4-addition to the Michael acceptor part of the molecule occurs, followed by a prototropy
  • , leading to an intermediate enol that, after a keto–enol equilibrium and aromatization, gives the indolone 7. For the indole 6 and the cinnoline 8, the synthesis starts with the protonation of the oxygen atom of the conjugated carbonyl group of the 1,4-diketone, followed by an imine formation between the
  • secondary amine and the nonconjugated carbonyl unit. Next, an intramolecular 1,2-addition to the Michael acceptor part of the molecule, previously activated by acid catalysis, takes place (after an imine–enamine equilibrium for the indole pathway), followed by a prototropy, the release of a water molecule
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Published 17 Jul 2020

Models of necessity

  • Timothy Clark and
  • Martin G. Hicks

Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137

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  • become apparent [40]. This is because non-equilibrium structures such as transition states that cannot be described by the conventional Lewis model are passed through during reactions. Quantum chemical methods, often in combination with molecular dynamics, can predict the course of a specific reaction
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Published 13 Jul 2020

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

  • Csilla Hargitai,
  • Györgyi Koványi-Lax,
  • Tamás Nagy,
  • Péter Ábrányi-Balogh,
  • András Dancsó,
  • Gábor Tóth,
  • Judit Halász,
  • Angéla Pandur,
  • Gyula Simig and
  • Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

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  • intermediates 13, results in hydroxyisoindolines 11, which can finally tautomerize to aldehydes 2a,b. In the previous report, we have demonstrated the existence of an equilibrium in the course of the transformation of 1a to 2a by trapping isoindole intermediate 4a with N-phenylmaleimide as a dienophile in the
  • acid-catalyzed reaction of both aldehydes 1a and 2a [1]. Moreover, as a reverse reaction, the formation of aldehyde 1a was observed in the transformation of aldehyde 2a under similar conditions [1]. However, this equilibrium is obviously influenced by the formation of the dimer-like products. The
  • ), and δC= (142.5) showed a considerable line-broadening (coalescence), revealing a partially hindered rotation of the formylphenyl moiety, i.e., the occurrence of a conformational equilibrium has to be taken into account. Even the δHC−N 13C NMR signal remained under the noise level, indicating that the
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Published 13 Jul 2020

A dynamic combinatorial library for biomimetic recognition of dipeptides in water

  • Florian Klepel and
  • Bart Jan Ravoo

Beilstein J. Org. Chem. 2020, 16, 1588–1595, doi:10.3762/bjoc.16.131

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  • library to be under thermodynamic control. Therefore, the equilibrium responds to stimuli such as addition of a template, which would stabilize a suitable receptor and thus amplifies its formation. This strategy has led to the discovery of many artificial receptors [7][8][9][10], with thiolate disulfide
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Published 02 Jul 2020

Heterogeneous photocatalysis in flow chemical reactors

  • Christopher G. Thomson,
  • Ai-Lan Lee and
  • Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

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Published 26 Jun 2020

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

  • Carlos H. Escalante,
  • Eder I. Martínez-Mora,
  • Carlos Espinoza-Hicks,
  • Alejandro A. Camacho-Dávila,
  • Fernando R. Ramos-Morales,
  • Francisco Delgado and
  • Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

Graphical Abstract
  • intermolecular interactions (NCIs) between aromatic rings (π···π) [58][59] and alkyl and aromatic ring (Csp3–H)···π stackings [59][60][61][62] are widely recognized, from both the experimental and theoretical viewpoint, as a major factor governing the conformational equilibrium, supramolecular assembly and
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Published 17 Jun 2020

Oxime radicals: generation, properties and application in organic synthesis

  • Igor B. Krylov,
  • Stanislav A. Paveliev,
  • Alexander S. Budnikov and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

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  • established that the studied iminoxyl radicals reversibly dimerized in the solution. For sterically unhindered dialkyliminoxyl radicals, the radical–dimer equilibrium was quickly reached, shifted toward the dimer, while a first-order decay kinetics of was observed for the iminoxyl radical. For sterically
  • hindered tert-butylmethyliminoxyl and diisopropyliminoxyl radicals, as well as for diaryl and alkylaryliminoxyl radicals, the radical–dimer equilibrium was reached slowly, it was shifted toward the free radical, and a second-order decay kinetics was observed. The first synthesized long-lived iminoxyl
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Published 05 Jun 2020

Activated carbon as catalyst support: precursors, preparation, modification and characterization

  • Melanie Iwanow,
  • Tobias Gärtner,
  • Volker Sieber and
  • Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

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  • determination of adsorbed gas [117]. As a result, physisorption isotherms are obtained by plotting the amount of adsorbed gas na in mol g−1 against the equilibrium relative pressure (p/p0). The resulting isotherms can be grouped in six different types. Type 1 isotherms are concave to the p/p0 axis and na
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Published 02 Jun 2020

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

  • Rasa Keruckiene,
  • Simona Vekteryte,
  • Ervinas Urbonas,
  • Matas Guzauskas,
  • Eigirdas Skuodis,
  • Dmytro Volyniuk and
  • Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

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  • with the Gaussian software [26]. Firstly, the equilibrium conformer search at the ground state was performed by using the MMFF (molecular mechanics force fields) method, and this geometry was used for further optimization. The vertical singlet and triplet energy values were calculated by using the
  • based on m-MTDATA:1:PO-T2T recorded at different voltages (c). EQE, current and power efficiencies of OLED and equilibrium energy diagram for the light-emitting layer m-MTDATA:1:PO-T2T (d, inset). Current density and brightness versus voltages for the device and photoelectron emission spectrum of the
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Published 28 May 2020

Copper-based fluorinated reagents for the synthesis of CF2R-containing molecules (R ≠ F)

  • Louise Ruyet and
  • Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

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  • substrates. Based on 19F NMR studies, the authors suggested the following mechanism: first the in situ generation of a CuCF2H complex from TMSCF2H in equilibrium with the corresponding cuprate (Cu(CF2H)2−) occurred followed by the reaction with terminal alkynes under basic conditions. The resulting
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Published 18 May 2020

Aryl-substituted acridanes as hosts for TADF-based OLEDs

  • Naveen Masimukku,
  • Dalius Gudeika,
  • Oleksandr Bezvikonnyi,
  • Ihor Syvorotka,
  • Rasa Keruckiene,
  • Dmytro Volyniuk and
  • Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

Graphical Abstract
  • structures and equilibrium energy diagrams of the devices are presented in Figure 6a. The values of ionization potentials and electron affinities of solid samples of compounds 3, 4, and 6 were taken as HOMO and LUMO levels as the first approximation (Figure 4b, Table 2). In the devices, MoO3 and LiF were
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Published 13 May 2020

Copper catalysis with redox-active ligands

  • Agnideep Das,
  • Yufeng Ren,
  • Cheriehan Hessin and
  • Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

Graphical Abstract
  • in equilibrium with a spectator bis-nitrene species 19 and proceeded through styrene 20 insertion, followed by ring closure and release of the aziridine. Interestingly, this otherwise classical mechanism is enabled by the accessibility of doublet and quadruplet states close in energy and this
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Published 24 Apr 2020

Aldehydes as powerful initiators for photochemical transformations

  • Maria A. Theodoropoulou,
  • Nikolaos F. Nikitas and
  • Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

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  • –54, respectively, establishing an equilibrium between the dormant species and the active radicals, which was required for a controlled radical polymerization. No polymerization product was detected in the absence of the benzaldehyde derivatives 52–54, respectively, as well as when the polymerization
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Published 23 Apr 2020

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

  • Péter Bagi,
  • Réka Herbay,
  • Nikolett Péczka,
  • Zoltán Mucsi,
  • István Timári and
  • György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

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  • variety of bases suggested that the base-mediated isomerization leads to a thermodynamic equilibrium between phospholene oxides 1 and 4 catalyzed by the base (see Supporting Information File 1 for the results). In order to test this hypothesis, the two model compounds (1a and 1h) were refluxed with Cs2CO3
  • (Table 3). These experiments suggested that the base-mediated isomerization leads to an equilibrium, which is in accordance with other reports in the literature [42]. Thus, this base-mediated isomerization was not studied further with other 3-phospholene oxide derivatives 1. Isomerization of 3
  • ), one may predict a well-balanced equilibrium between the 2- or 3-phospholene oxides 4 or 1 in a final state. The experimental results obtained under basic or thermal conditions support this equilibrium concept. In contrast, nearly complete isomerization was observed via the formation of
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Published 22 Apr 2020

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

  • Dong Cai,
  • ZhiHua Zhang,
  • Yufan Meng,
  • KaiLi Zhu,
  • LiYi Chen,
  • ChangXiang Yu,
  • ChangWei Yu,
  • ZiYi Fu,
  • DianShen Yang and
  • YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

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  • agent [12]. Piperazinyl amide fragments have the ability to form several hydrogen bonds, modulate the acid–base equilibrium constant and change the octanol–water partition coefficient [13]. They are considered as the basic motif for designing many biologically active molecules [14][15]. Some piperazinyl
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Published 21 Apr 2020

Synthesis of C70-fragment buckybowls bearing alkoxy substituents

  • Yumi Yakiyama,
  • Shota Hishikawa and
  • Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

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  • equilibrium between the Pd(IV) intermediates through C–H bond activation. Keywords: buckybowl; C70; rearrangement through C–H bond activation; Introduction The study of buckybowls, the bowl-shaped π-conjugated aromatic hydrocarbons corresponding to the fragments of fullerenes, pioneered by the works on
  • above results strongly suggested the existence of an equilibrium between the intermediates corresponding to products 5b and 5c. A possible mechanism is shown in Scheme 2 [21][22][23][24][25]. After the oxidative addition of 4b to Pd0 to generate intermediate A, the neutral palladium(II) intermediate B
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Published 15 Apr 2020

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

  • Bernd Strehmel,
  • Christian Schmitz,
  • Ceren Kütahya,
  • Yulian Pang,
  • Anke Drewitz and
  • Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

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  • and deactivated by reaction with Cu(II) resulting in formation of dormant species and Cu(I). Altogether, these reactions must be seen as equilibrium coexisting together. Researchers also spent much time to develop photo-ATRP procedures working without any metal catalyst; that is the photoinduced metal
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Published 18 Mar 2020

Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid

  • Fei You,
  • Xing He,
  • Song Gao,
  • Hong-Ru Li and
  • Liang-Nian He

Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34

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  • vacuum degree is another factor to affect the intermolecular esterification as different vacuum degree can result in a different water removal rate, which may lead to a different equilibrium toward estolides product. Five different levels of vacuum degrees were applied to the reaction system, the results
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Published 10 Mar 2020

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

  • Clément Ghiazza and
  • Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

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  • , this species is in an equilibrium with the −SeCF3 anion. As proposed by Hor and Weng, Deng and Xiao also suggested that CuSeCF3 was the active species in the mechanism. In 2016, the group of Rueping described a sequential copper-catalyzed selenocyanation of aryldiazonium salts, followed by
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Published 03 Mar 2020

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

  • Narasimhamurthy Rajeev,
  • Toreshettahally R. Swaroop,
  • Ahmad I. Alrawashdeh,
  • Shofiur Rahman,
  • Abdullah Alodhayb,
  • Seegehalli M. Anil,
  • Kuppalli R. Kiran,
  • Chandra,
  • Paris E. Georghiou,
  • Kanchugarakoppal S. Rangappa and
  • Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

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  • favor of 4cB. The resulting calculated equilibrium constant of 2.042, corresponding to a 67.1/32.9 ratio of the rotamers (4cB/4cA), was in good agreement with the experimentally by 1H NMR (CDCl3) observed ratio of 65/35. Significantly, the single crystal of 4c, which afforded the crystal structure shown
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Published 03 Feb 2020

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

  • Afef Mabrouki,
  • Malek Fouzai,
  • Armand Soldera,
  • Abdelkader Kriaa and
  • Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

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  • intermediate 3 (Scheme 1). Table 1 shows the yields and melting points of the synthesized compounds 2 and 4. The tautomeric equilibrium of compound 3 is illustrated in Scheme 2. On the basis of FTIR data, it has been concluded that in solution, the equilibrium is shifted to the thione form 3a rather than the
  • molecular dipole moments. Orange, fluorocarbon compounds; blue, hydrocarbon compounds; green (horizontal line), dipole moment (µ0) of RC. Synthesis of oxadiazole derivatives 2 and 4. Tautomeric equilibrium of compound 3. Obtained oxadiazole derivatives 2 and 4. DSC thermograms data of compounds 2 and 4
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Published 31 Jan 2020

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

  • Sarah Kölsch,
  • Heiko Ihmels,
  • Jochen Mattay,
  • Norbert Sewald and
  • Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

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  • to DNA only with one of the components of the photochromic equilibrium. Moreover, these ligand–DNA interactions can be photochemically switched between the binding and nonbinding form. Interestingly, the photochromic systems applied in this context are almost exclusively photoinduced
  • electrocyclization or E-to-Z isomerization reactions, whereas the well-established photochromic cycloaddition–cycloreversion equilibrium to establish photoswitchable DNA binders has so far been widely neglected. In fact, there is only one reported example for the use of the reversible photoinduced dimerization of
  • photoswitchable DNA binders based on the photocycloaddition–photocycloreversion equilibrium. In fact, some selected styrylquinolizinium derivatives have already been shown to bind to DNA [61][62][63][64][65][66][67], however, their photocycloaddition reaction and the propensity of the corresponding photodimers to
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Published 23 Jan 2020

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

  • Xiaodong Zhang,
  • Jun Xie,
  • Zhiling Xu,
  • Zhu Tao and
  • Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

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  • % (BALE) and 8.02% (BALE–Q[8]), respectively in artificial intestinal juice. In addition, the release and degradation tended to reach an equilibrium (Figure 10). The release rates of the BALE–Q[8] complex was slower than that of BALE in artificial intestinal juice, but it was faster than the BALE in
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Published 10 Jan 2020

Photocontrolled DNA minor groove interactions of imidazole/pyrrole polyamides

  • Sabrina Müller,
  • Jannik Paulus,
  • Jochen Mattay,
  • Heiko Ihmels,
  • Veronica I. Dodero and
  • Norbert Sewald

Beilstein J. Org. Chem. 2020, 16, 60–70, doi:10.3762/bjoc.16.8

Graphical Abstract
  • corresponding signals. A representative series of spectra is presented in Figure 1 for polyamide P1. In the thermal equilibrium, approximately 6% of the Z-isomer was present (Figure 1A). Upon irradiation at 350 nm, this fraction steadily increased and reached a level of 65% after 50 min irradiation (Figure 1B
  • temperature, and even after 18 days, 13% of the Z-isomer were still present. The thermal equilibrium (5% Z-configuration) was reached only after 40 days in the dark (data not shown). In a previous study, the same azobenzene species incorporated in a hairpin peptide reached a photostationary state of 85% Z
  • powerful strategy to obtain photoswitchable Im/Py hairpin polyamides capable of interaction with the dsDNA minor groove only in the Z-configuration. Section of the 1H NMR (600 MHz) spectrum of polyamide P1. A) Initial thermal equilibrium. B) After irradiation at 350 nm for 10 min. C) After irradiation at
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Published 09 Jan 2020
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