Reversible Rearrangement Research Articles

SAMPL-seq reveals micron-scale spatial hubs in the human gut microbiome.

The local arrangement of microbes can profoundly impact community assembly, function and stability. However, our understanding of the spatial organization of the human gut microbiome at the micron scale is limited. Here we describe a high-throughput and streamlined method called Split-And-pool Metagenomic Plot-sampling sequencing (SAMPL-seq) to capture spatial co-localization in a complex microbial consortium. The method obtains microbial composition of micron-scale subcommunities through split-and-pool barcoding. SAMPL-seq analysis of the healthy human gut microbiome identified bacterial taxa pairs that consistently co-occurred both over time and across multiple individuals. These co-localized microbes organize into spatially distinct groups or 'spatial hubs' dominated by Bacteroidaceae, Ruminococcaceae and Lachnospiraceae families. Using inulin as a dietary perturbation, we observed reversible spatial rearrangement of the gut microbiome where specific taxa form new local partnerships. Spatial metagenomics using SAMPL-seq can unlock insights into microbiomes at the micron scale.

UV-curing 3D printing of high-performance, recyclable, biobased photosensitive resin enabled by dual-crosslinking networks

UV-curing 3D printing technologies based on vat photopolymerization have gained increasing interest in rapidly manufacturing high-quality custom-designed objects. However, they are still challenged by the non-renewability of photosensitive resins in future large-scale applications. Herein, a high-performance, recyclable, biobased carboxyl-terminated unsaturated polyester is developed from itaconic acid and bio-diols, which involves the formation of dual-crosslinking networks, i.e., covalent crosslinking of unsaturated double bonds and non-covalent coordination interaction between terminal carboxyl and ZnCl2. Dual-crosslinking networks greatly increase tensile strength from 31 to 43 MPa by 40 %. More importantly, taking advantage of the dynamic reversibility of coordination and thermally-activated transesterification by ZnCl2, the universal problem, i.e. the anisotropic mechanical property in 3D printing caused by printing layers, can be effectively solved, attributed to reversible rearrangement and reassociation between printing layers. Moreover, after the 3D printing products are pulverized into microparticles, the powders can be thermally compressed into new materials with a 70 % recovery in tensile strength. In addition, these powders can also be used as reinforcing fillers to enhance the virgin resin, the optimum tensile strength and elastic modulus further increase to 52 MPa and 1019 MPa by 40 % with 1 wt% dosages. Therefore, this study is a pioneering pathway for the concurrent achievement of good mechanical properties (52 MPa) and high biomass content (96 wt%) for UV-curable 3D printing photosensitive resin.

The Balance between Protealysin and Its Substrate, the Outer Membrane Protein OmpX, Regulates Serratia proteamaculans Invasion.

Serratia are opportunistic bacteria, causing infections in plants, insects, animals and humans under certain conditions. The development of bacterial infection in the human body involves several stages of host-pathogen interaction, including entry into non-phagocytic cells to evade host immune cells. The facultative pathogen Serratia proteamaculans is capable of penetrating eukaryotic cells. These bacteria synthesize an actin-specific metalloprotease named protealysin. After transformation with a plasmid carrying the protealysin gene, noninvasive E. coli penetrate eukaryotic cells. This suggests that protealysin may play a key role in S. proteamaculans invasion. This review addresses the mechanisms underlying protealysin's involvement in bacterial invasion, highlighting the main findings as follows. Protealysin can be delivered into the eukaryotic cell by the type VI secretion system and/or by bacterial outer membrane vesicles. By cleaving actin in the host cell, protealysin can mediate the reversible actin rearrangements required for bacterial invasion. However, inactivation of the protealysin gene leads to an increase, rather than decrease, in the intensity of S. proteamaculans invasion. This indicates the presence of virulence factors among bacterial protealysin substrates. Indeed, protealysin cleaves the virulence factors, including the bacterial surface protein OmpX. OmpX increases the expression of the EGFR and β1 integrin, which are involved in S. proteamaculans invasion. It has been shown that an increase in the invasion of genetically modified S. proteamaculans may be the result of the accumulation of full-length OmpX on the bacterial surface, which is not cleaved by protealysin. Thus, the intensity of the S. proteamaculans invasion is determined by the balance between the active protealysin and its substrate OmpX.

Effect of acylhydrazone self-healing agents with different structures on the properties of SBS modified asphalt waterproofing membrane

To prepare SBS modified asphalt (SMA) waterproofing membrane with excellent self-healing performance, in this paper, four self-healing agents (ASHA-A, ASHA-B, ASHA-C, ASHA-D) with acylhydrazone bonds and carbon-carbon double bonds (CC) were synthesized, and were used to prepare self-healing SMA waterproofing membranes (SSMA-A, SSMA-B, SSMA-C, SSMA-D). The effects of ASHAs with different structures on the structure, high and low temperature properties, joint peel strength and self-healing performance of SSMAs were investigated. The Fourier transform infrared spectroscopy and fluorescence microscope results showed that acylhydrazone bonds of ASHAs were introduced into the chains of SBS molecules, and the SBS in SSMAs occurred crosslinking through the CC of ASHAs and SBS, the crosslinked network structures of SBS in SSMA-C and SSMA-D were denser and more complete because ASHA-C and ASHA-D contained more CC involved in the crosslinking reaction. The softening point and low temperature flexibility of SSMAs were enhanced by the formation of the SBS crosslinked network structure, and the optimum dosage of ASHAs was 0.6%. The joint peel strength of SSMA-A, SSMA-B, SSMA-C and SSMA-D increased by 26.68%, 31.25%, 49.52% and 56.97% compared to SMA. The introduction of acylhydrazone bonds with reversible fracture and rearrangement significantly improved the crack self-healing performance of SMA, the impermeability times of SMA, SSMA-A, SSMA-B, SSMA-C and SSMA-D were 13.28 min, 37.29 min, 42.53 min, 53.34 min and 59.67 min after self-healing at 40℃ for 8 h, which indicated that ASHA-D with benzene ring and multiple CC had the best improvement in self-healing performance of SMA.

A Dual Active Site Organic–Inorganic Poly(O‐Phenylenediamine)/NH4V3O8 Composite Cathode Material for Aqueous Zinc‐Ion Batteries

AbstractAqueous zinc‐ion batteries, considered one of the important candidate technologies for green and environmentally friendly large‐scale energy storage, hinge upon the performance of cathode materials as the key factor driving their development. Vanadate oxide is a promising cathode material due to its high theoretical capacity; furthermore, in order to accelerate the reaction kinetics, ion or molecular intercalation is often utilized. However, non‐electrochemically active intercalants tend to cause capacity degradation. In this study, a one‐step hydrothermal method is employed to intercalate electrochemically active poly‐o‐phenylenediamine (PoPDA) into the interlayers of NH4V3O8 (NVO), with graphene oxide (GO) being used to further improve the conductivity of the composite material (NVO/PoPDA@GO). The insertion of PoPDA expands the interlayer spacing of the NVO, alters the charge distribution, and enhances the migration rate of Zn2+ among the hybrid materials. Additionally, PoPDA serves as a support within the interlayers, improving the material stability. Moreover, the reversible transformation and rearrangement of chemical bonds (C═N/C─N) in PoPDA allows for coordination with Zn2+, providing additional capacity. As a result, NVO/PoPDA@GO exhibits excellent electrochemical performance, releasing a specific capacity of 433 mAh g−1 at 0.5 A g−1, even with a capacity of 224 mAh g−1 at 5 A g−1. This work provides a promising direction for the preparation of organic–inorganic composite cathode materials with dual active components.

Reversible rearrangement of the cellular cytoskeleton: A key to the broad-spectrum antiviral activity of novel amphiphilic polymers.

The battle against emerging viral infections has been uneven, as there is currently no broad-spectrum drug available to contain the spread of novel pathogens throughout the population. Consequently, the pandemic outbreak that occurred in early 2020 laid bare the almost empty state of the pandemic box. Therefore, the development of novel treatments with broad specificity has become a paramount concern in this post-pandemic era. Here, we propose copolymers of poly (sodium 2-(acrylamido)-2-methyl-1-propanesulfonate) (PAMPS) and poly (sodium 11-(acrylamido)undecanoate (AaU), both block (PAMPS75-b-PAaUn) and random (P(AMPSm-co-AaUn)) that show efficacy against a broad range of alpha and betacoronaviruses. Owing to their intricate architecture, these polymers exhibit a highly distinctive mode of action, modulating nano-mechanical properties of cells and thereby influencing viral replication. Through the employment of confocal and atomic force microscopy techniques, we discerned perturbations in actin and vimentin filaments, which correlated with modification of cellular elasticity and reduction of glycocalyx layer. Intriguingly, this process was reversible upon polymer removal from the cells. To ascertain the applicability of our findings, we assessed the efficacy and underlying mechanism of the inhibitors using fully differentiated human airway epithelial cultures, wherein near-complete abrogation of viral replication was documented. Given their mode of action, these polymers can be classified as biologically active nanomaterials that exploit a highly conserved molecular target-cellular plasticity-proffering the potential for truly broad-spectrum activity while concurrently for drug resistance development is minimal.

Mechanical Flexibility in Halogen-Substituted Niacin and Isonicotinamide

Understanding the role of molecular packing and intermolecular interactions in determining mechanical properties is significant for the development of mechanically flexible organic crystals. Here, we obtain a sequence of plastically twisted crystals (3) and elastically bent crystals (2) based on derivatives of nicotinic acid and isonicotinamide. The relationship between the macroscopic mechanical properties and microscopic crystal packing is discussed. Weak and dispersed weak interactions are found to play a significant role in controlling molecular movement to dissipate the strain. The introduction of a combination of noninterfering halogen bonds and weak hydrogen-bonding and van der Waals (vdW) interactions among π–π columns is considered to play a crucial role in achieving irreversible twist deformation. For the two elastically bent crystals, the molecules assemble themselves into a herringbone packing arrangement with weak and strong interactions in their interlayers, respectively, to allow a reversible rearrangement of molecules, compressing along the inner arc and extending along the outer arc. We believe that our work will provide guidance to understand and design mechanically flexible crystals and will be helpful to broaden it to a more generalized system.

Polarity and Dielectric Property Control Triggered by a Coordinated Solvent Molecule Exchange in Luminescent Mononuclear Aluminium(III) Complexes.

The development of molecule-based multifunctional switchable materials that exhibit a switch of polarity and dielectric property are extremely limited. We have demonstrated solvent-vapour-induced reversible molecular rearrangements between nonpolar crystals [Al(sap)(acac)(sol)] (H2 sap=2-salicylideneaminophenol, acac=acetylacetonate, sol=MeOH (1), EtOH (2)) and polar crystal [Al(sap)(acac)(DMSO)] (3). This crystal-to-crystal structural transformation was accompanied by a switch of second harmonic generation (SHG) and dielectric properties, including the formation of ferroelectric domains, thus reflecting the SHG-active polar Cc space group of 3. This is the first reported example of dielectric properties and polarity switching in luminescent mononuclear aluminium(III) complexes, which exhibit strong green emission in the solid state.

Dynamic state of plasmid genomic architectures resulting from XerC/D-mediated site-specific recombination in Acinetobacter baumannii Rep_3 superfamily resistance plasmids carrying blaOXA-58 - and TnaphA6-resistance modules.

The acquisition of bla OXA genes encoding different carbapenem-hydrolyzing class-D β-lactamases (CHDL) represents a main determinant of carbapenem resistance in the nosocomial pathogen Acinetobacter baumannii. The blaOXA-58 gene, in particular, is generally embedded in similar resistance modules (RM) carried by plasmids unique to the Acinetobacter genus lacking self-transferability. The ample variations in the immediate genomic contexts in which blaOXA-58 -containing RMs are inserted among these plasmids, and the almost invariable presence at their borders of non-identical 28-bp sequences potentially recognized by the host XerC and XerD tyrosine recombinases (pXerC/D-like sites), suggested an involvement of these sites in the lateral mobilization of the gene structures they encircle. However, whether and how these pXerC/D sites participate in this process is only beginning to be understood. Here, we used a series of experimental approaches to analyze the contribution of pXerC/D-mediated site-specific recombination to the generation of structural diversity between resistance plasmids carrying pXerC/D-bounded bla OXA-58- and TnaphA6-containing RM harbored by two phylogenetically- and epidemiologically-closely related A. baumannii strains of our collection, Ab242 and Ab825, during adaptation to the hospital environment. Our analysis disclosed the existence of different bona fide pairs of recombinationally-active pXerC/D sites in these plasmids, some mediating reversible intramolecular inversions and others reversible plasmid fusions/resolutions. All of the identified recombinationally-active pairs shared identical GGTGTA sequences at the cr spacer separating the XerC- and XerD-binding regions. The fusion of two Ab825 plasmids mediated by a pair of recombinationally-active pXerC/D sites displaying sequence differences at the cr spacer could be inferred on the basis of sequence comparison analysis, but no evidence of reversibility could be obtained in this case. The reversible plasmid genome rearrangements mediated by recombinationally-active pairs of pXerC/D sites reported here probably represents an ancient mechanism of generating structural diversity in the Acinetobacter plasmid pool. This recursive process could facilitate a rapid adaptation of an eventual bacterial host to changing environments, and has certainly contributed to the evolution of Acinetobacter plasmids and the capture and dissemination of bla OXA-58 genes among Acinetobacter and non-Acinetobacter populations co-residing in the hospital niche.

Negative Differential Resistance and Long-Lived Changes in the Electrical Conductivity of Carbon Composites Induced by Electrothermal Effects

In this study, the negative differential resistance (NDR) phenomenon in two-terminal devices composed of pyrogallol-formaldehyde/ZrO2 composite materials is investigated. It is demonstrated that the NDR is caused by electrothermal effects, which can be observed through the dependence of the NDR on both voltage and temperature. Additionally, it is showed that the NDR peak current and peak/valley voltages can be effectively modulated using electrical pulses that produce mild Joule heating. This modulation arises from the formation of a conductive metastable state, which decays to equilibrium according to power law kinetics. It is suggested that this metastable state is generated through a reversible structural rearrangement induced by heat. The ability to electronically tune the NDR characteristics of carbon composites may have potential applications in electronically controlled oscillators and neuromorphic circuits.

Approaching the Dimerization Mechanism of Small Molecule Inhibitors Targeting PD-L1 with Molecular Simulation.

Inhibitors blocking the PD-1/PD-L1 immune checkpoint demonstrate impressive anti-tumor immunity, and small molecule inhibitors disclosed by the Bristol-Myers Squibb (BMS) company have become a hot topic. In this work, by modifying the carbonyl group of BMS-202 into a hydroxyl group to achieve two enantiomers (MS and MR) with a chiral center, we found that this is an effective way to regulate its hydrophobicity and thus to reduce the negative effect of polar solvation free energy, which enhances the stability of PD-L1 dimer/inhibitor complexes. Moreover, we studied the binding modes of BMS-200 and BMS-202-related small molecule inhibitors by molecular dynamics simulation to explore their inhibitory mechanism targeting PD-L1 dimerization. The results showed that the size exclusion effect of the inhibitors triggered the rearrangement of the residue ATyr56, leading to the formation of an axisymmetric tunnel-shaped pocket, which is an important structural basis for improving the binding affinity of symmetric inhibitors with PD-L1. Furthermore, after inhibitor dissociation, the conformation of ATyr123 and BMet115 rearranged, which blocked the entrance of the binding pocket, while the reverse rearrangements of the same residues occurred when the PD-L1 monomer was complexed with the inhibitors, preparing PD-L1 for dimerization. Overall, this study casts a new light on the inhibitory mechanism of BMS inhibitors targeting PD-L1 dimerization and provides an idea for designing novel small molecule inhibitors for future cancer immunotherapy.

Molecular Switch Cobalt Redox Shuttle with a Tunable Hexadentate Ligand.

Strong-field hexadentate ligands were synthesized and coordinated to cobalt metal centers to result in three new low-spin to low-spin Co(III/II) redox couples. The ligand backbone has been modified with dimethyl amine groups to result in redox potential tuning of the Co(III/II) redox couples from -200 to -430 mV versus Fc+/0. The redox couples surprisingly undergo a reversible molecular switch rearrangement from five-coordinate Co(II) to six-coordinate Co(III) despite the ligands being hexadentate. The complexes exhibit modestly faster electron self-exchange rate constants of 2.2-4.2 M-1 s-1 compared to the high-spin to low-spin redox couple [Co(bpy)3]3+/2+ at 0.27 M-1 s-1, which is attributed to the change in spin state being somewhat offset by this coordination switching behavior. The complexes were utilized as redox shuttles in dye-sensitized solar cells with the near-IR AP25 + D35 dye system and exhibited improved photocurrents over the [Co(bpy)3]3+/2+ redox shuttle (19.8 vs 18.0 mA/cm2). Future directions point toward pairing the low-spin to low-spin Co(II/III) tunable series to dyes with significantly more negative highest occupied molecular orbital potentials that absorb into the near-IR where outer sphere redox shuttles have failed to produce efficient dye regeneration.

Intramolecular crankshaft-type rearrangement in a photoisomerised glycoconjugate.

High-resolution NMR spectroscopy revealed that a novel glycoconjugate, consisting of two β-glucopyranoses attached to a quinazolinone-like structure, exhibited photoisomerization around the -N-N[double bond, length as m-dash] and [double bond, length as m-dash]CH-C- bonds of the -N-N[double bond, length as m-dash]CH-C- linkage in the same timeframe (the so-called "crankshaft rotation") upon exposure to UV light. Experimental NMR data combined with DFT calculations discovered that the attachment of carbohydrate residues to photoactive compounds significantly changed the isomerization process and intramolecular rearrangement compared to the unglycosylated system, while the overall molecular structure remained virtually unchanged.

Exploration of bifunctional Vanadium-based Metal-Organic framework with double active centers for Potassium-ion batteries

Exploration of suitable electrode hosts with large open channels that can reversibly accommodate K+ with large radius have been extensively investigated. Nevertheless, the reported inorganic counterparts were inevitably restricted by the difficulty of large K+ diffusion capability in crystal structure and the huge volume change. Herein, we report a bifunctional vanadium-based metal–organic framework (MIL-47) with double active centers and larger lamellar spacing that could serve as both cathode and anode material, respectively by controlling the redox potential range in potassium-ion batteries. The results suggest that the stable K-storage mechanism is the reversible rearrangement of the conjugated carboxyl groups of organic terephthalic acid into enolate and the reversible redox activity of V ions, with the specific capacity of 272 mAh g−1 (0.01–1.5 V) and 50 mAh g−1 (1.5–3.8 V) at the current density of 10 mA g−1 for MIL-47 anode and MIL-47 cathode, respectively. The unsaturated functional group of MIL-47 and the intermediate bridged V atom not only provide multi-dimensional channels for electron and ion transport but also stabilize its crystal structure. Additionally, a symmetric full-cell in potassium-ion batteries based on MIL-47 was constructed successfully by avoiding the utilization of K metal with safety concerns. Our results provide new insight into structure design for next-generation large-scale energy storage applications.

The dynamic network of IS30 transposition pathways.

The E. coli element IS30 has adopted the copy-out-paste-in transposition mechanism that is prevalent in a number of IS-families. As an initial step, IS30 forms free circular transposition intermediates like IS minicircles or tandem IS-dimers by joining the inverted repeats of a single element or two, sometimes distantly positioned IS copies, respectively. Then, the active IR-IR junction of these intermediates reacts with the target DNA, which generates insertions, deletions, inversions or cointegrates. The element shows dual target specificity as it can insert into hot spot sequences or next to its inverted repeats. In this study the pathways of rearrangements of transposition-derived cointegrate-like structures were examined. The results showed that the probability of further rearrangements in these structures depends on whether the IS elements are flanked by hot spot sequences or take part in an IR-IR junction. The variability of the deriving products increases with the number of simultaneously available IRs and IR-IR joints in the cointegrates or the chromosome. Under certain conditions, the parental structures whose transposition formed the cointegrates are restored and persist among the rearranged products. Based on these findings, a novel dynamic model has been proposed for IS30, which possibly fits to other elements that have adopted the same transposition mechanism. The model integrates the known transposition pathways and the downstream rearrangements occurring after the formation of different cointegrate-like structures into a complex network. Important feature of this network is the presence of “feedback loops” and reversible transposition rearrangements that can explain how IS30 generates variability and preserves the original genetic constitution in the bacterial population, which contributes to the adaptability and evolution of host bacteria.

Understanding of Photo-Induced Reversible Rearrangement from Borepin to Borirane.

The first reversible photoisomerization between a borepin and a borirane was reported in the photo-induced reactions of B(npy)Ar2 (npy=2-(naphthalen-1-yl) pyridine, Ar=phenyl or electron rich aryl; S. Wang, et al. Angew. Chem. Int. Ed. 2019, 58, 6683-6687). In this work, the detailed mechanisms of the unprecedented reversible photoisomerization between the borepin (compound a) and the borirane (compound b) of B(npy)Ph2 in the first excited singlet (S1 ) state and the ground (S0 ) state were studied by carrying out calculations with the complete active space self-consistent field (CASSCF) and its second-order perturbation (CASPT2) methods combined with time-dependent density functional theory (TD-DFT). The calculation results show that photoexcitation of a-S0 at 365 nm and b-S0 at 450 nm populate their S1 state with evident charge transfer characteristics. The photoisomerization is triggered in the S1 state and ends in the S0 state, at which the intersection points in a (S1 /S0 )x intersection seam participate in and promote phenyl migration and ring-closure processes. Furthermore, we reveal that the not large energy difference (less than 0.6 eV) and similar conjugation properties of π electrons between a-S0 and b-S0 are responsible for their unique photo-reversible reactivity, compared with those of the isomers of the thermally reversible compound B(ppy)Mes2 . Our results contribute to an understanding of the excited-state reactivity of organoboron compounds and will be useful to support the design of new boron-based photo-responsive materials.

Superior Multielectron-Transferring Energy Storage by π-d Conjugated Frameworks.

Reversible multielectron-transfer materials are of considerable interest because of the potential impact to advance present electrochemical energy storage technology by boosting energy density. To date, a few oxide-based materials can reach an electron-transfer number per metal-cation (eM ) larger than 2 upon a (de)intercalation mechanism. However, these materials suffer from degradation due to irreversible rearrangements of the cation-oxygen bonds, and are based on precious metals, for example, Ir and Ru. Hence, a design of the non-oxide-based reversible multielectron-transfer materials with abundant elements can provide a promising alternative. Herein, it is demonstrated that the bis(diimino)copper framework can show eM = 3.5 with cation/anion co-redox mechanism together with a dual-ion mechanism. In this study, the role of the cation-anion interactions is unveiled by using an experiment/theory collaboration applied to a series of the model non-oxide abundant electrode systems based on different metal-nitrogen bonds. These models provide designer multielectron-transfer due to the tunable π-d conjugated electronic structures. It is found that the Cu-nitrogen bonds show a unique reversible rearrangement upon Li-intercalation, and this process responds to acquire a significant reversible multielectron-transfer. This work provides new insights into the affordable multielectron-transfer electrodes and uncovers an alternative strategy to advance the electrochemical energy storage reactions.

SYNTHESIS, CRYSTAL STRUCTURES AND MAGNETIC PROPERTIES OF COORDINATION COMPOUNDS WITH NITRONYL NITROXIDE RADICALS AND [M(HFAC)2] (M = CUII AND MNII)

The reaction of metal hexafluoroacetylacetonato [MII(hfac)2, M = Cu, Mn] with the stable nitronyl nitroxide 2−(3−isobutyl−pyrazole)−4,4,5,5−tetramethylimidazoline−1−oxyl−3−oxide (L), resulted in one dimensional zig−zag chain systems [{Cu(hfac)2}2L2]n and [CuMn(hfac)4L2]n. The main feature inherent in the nature of [{Cu(hfac)2}2L2]n single crystals is their ability to undergo reversible structural rearrangements with temperature variation, accompanied by anomalies of magnetism. The value of cmT shown strongly antiferromagnetic at low temperature and becomes ferromagnetic when the temperature increases. And the heteronuclear complex [CuMn(hfac)4L2]n shows antiferromagnetic interactions between manganese and nitronyl nitroxide.

Reversible structural rearrangement of π-expanded cyclooctatetraene upon two-fold reduction with alkali metals.

The chemical reduction of a π-expanded COT derivative, octaphenyltetrabenzocyclooctatetraene (1), with lithium or sodium metals in the presence of secondary ligands affords a new doubly-reduced product (1TR2-). The X-ray diffraction study revealed a reductive core rearrangement accompanied by the formation of a single C-C bond and severe twist of the central tetraphenylene core. The reversibility of two-electron reduction and core transformation is further confirmed by NMR spectroscopy and DFT calculations.

Исследование радиационного отклика оптического волокна при воздействии импульсного ионизирующего излучения

We have studied the radiation response of a single-mode optical fiber under the influence of pulsed photon and gamma-neutron radiation. The recovery time of the characteristics of the same optical fiber for one dose per pulse can vary within a wide range from a few milliseconds to several seconds, depending on various influencing factors. It is for the first time that we have experimentally recorded an increase of radiation-induced attenuation (RIA) of an optical fiber in the short-wavelength region after exposure to a pulsed neutron flux, simultaneously with RIA decrease in the long-wavelength region after the end of exposure and a subsequent RIA decrease in the entire studied wavelength range. This may mean a reversible rearrangement of the glass structure of the optical fiber. The RIA curves of the optical fibers under the influence of pulsed ionizing radiation are analyzed using the approaches of chemical kinetics. It has been established that the reaction order of the relaxation processes of short-lived radiation-induced color centers (RTCs) is fractional, which indicates a complex, possibly multi-stage process. After a few microseconds after exposure, all relaxation processes are in the diffusion region. The paper is the first to show that the characteristic RTCs relaxation time is directly related not only to temperature but also to the level of the stress-strain state of the optical fiber, and for an optical fiber with a pure-silica core, it is additionally related to the input optical power.