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Glycosylation is a predominant strategy plants use to fine-tune the properties of small molecule metabolites to affect their bioactivity, transport, and storage. It is also important in biotechnology and medicine as many glycosides are utilized in human health. Small molecule glycosylation is largely carried out by family 1 glycosyltransferases. Here, we report a structural and biochemical investigation of UGT95A1, a family 1 GT enzyme from Pilosella officinarum that exhibits a strong, unusual regiospecificity for the 3'-O position of flavonoid acceptor substrate luteolin. We obtained an apo crystal structure to help drive the analyses of a series of binding site mutants, revealing that while most residues are tolerant to mutations, key residues M145 and D464 are important for overall glycosylation activity. Interestingly, E347 is crucial for maintaining the strong preference for 3'-O glycosylation, while R462 can be mutated to increase regioselectivity. The structural determinants of regioselectivity were further confirmed in homologous enzymes. Our study also suggests that the enzyme contains large, highly dynamic, disordered regions. We showed that while most disordered regions of the protein have little to no implication in catalysis, the disordered regions conserved among investigated homologs are important to both the overall efficiency and regiospecificity of the enzyme. This report represents a comprehensive in-depth analysis of a family 1 GT enzyme with a unique substrate regiospecificity and may provide a basis for enzyme functional prediction and engineering.

Spectator ions have known and emerging roles in aqueous metal-cation chemistry, respectively directing solubility, speciation, and reactivity. Here, we isolate and structurally characterize the last two metastable members of the alkali uranyl triperoxide series, the Rb+ and Cs+ salts (Cs-U1 and Rb-U1). We document their rapid solution polymerization via small-angle X-ray scattering, which is compared to the more stable Li+, Na+ and K+ analogues. To understand the role of the alkalis, we also quantify alkali-hydroxide promoted peroxide deprotonation and decomposition, which generally exhibits increasing reactivity with increasing alkali size. Cs-U1, the most unstable of the uranyl triperoxide monomers, undergoes ambient direct air capture of CO2 in the solid-state, converting to Cs4[UVIO2(CO3)3], evidenced by single-crystal X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. We have attempted to benchmark the evolution of Cs-U1 to uranyl tricarbonate, which involves a transient, unstable hygroscopic solid that contains predominantly pentavalent uranium, quantified by X-ray photoelectron spectroscopy. Powder X-ray diffraction suggests this intermediate state contains a hydrous derivative of CsUVO3, where the parent phase has been computationally predicted, but not yet synthesized.

The transition of IgA antibodies into clinical development is crucial because they have the potential to create a new class of therapeutics with superior pathogen neutralization, cancer cell killing, and immunomodulation capacity compared to IgG. However, the biological role of IgA glycans in these processes needs to be better understood. This study provides a detailed biochemical, biophysical, and structural characterization of recombinant monomeric human IgA2, which varies in the amount/locations of attached glycans. Monomeric IgA2 antibodies were produced by removing the N-linked glycans in the CH1 and CH2 domains. The impact of glycans on oligomer formation, thermal stability, and receptor binding was evaluated. In addition, we performed a structural analysis of recombinant IgA2 in solution using Small Angle X-Ray Scattering (SAXS) to examine the effect of glycans on protein structure and flexibility. Our results indicate that the absence of glycans in the Fc tail region leads to higher-order aggregates. SAXS, combined with atomistic modeling, showed that the lack of glycans in the CH2 domain results in increased flexibility between the Fab and Fc domains and a different distribution of open and closed conformations in solution. When binding with the Fcα-receptor, the dissociation constant remains unaltered in the absence of glycans in the CH1 or CH2 domain, compared to the fully glycosylated protein. These results provide insights into N-glycans' function on IgA2, which could have important implications for developing more effective IgA-based therapeutics in the future.

The evaporation-induced self-assembly process of amphiphilic molecules (4POSS-DL-POM) in a mixed acetone/ n -decane solution is investigated using small-angle X-ray scattering. A series of scattering data analysis methods is employed to elucidate the structural evolution of heterocluster 4POSS-DL-POM from a fractal network to compact nanoclusters, followed by the formation of core–shell nanoclusters, and ultimately to hcp superlattice structure. [Display omitted] Self-assembly of nanoclusters (NCs) is an effective synthetic method for preparing functionalized nanomaterials. However, the assembly process and mechanisms in solutions still remain ambiguous owing to the limited strategies to monitor intermediate assembled states. Herein, the self-assembly process of amphiphilic molecule 4POSS-DL-POM (consisting of four polyhedral oligomeric silsesquioxanes, a dendritic linker, and one polyoxometalate) by evaporation of acetone in a mixed acetone/ n -decane solution is monitored by time-resolved synchrotron small-angle X-ray scattering (SAXS). Scattering data assessments, including Kratky analysis, pair distance distribution function, and model fitting, track the self-assembly process of 4POSS-DL-POM from a fractal network to compact NCs, then to core–shell NCs, and finally to superlattice structure. The calculated average aggregation number of a core–shell NC is 11 according to the parameters obtained from core-shell model fitting, in agreement with electron microscopy. The fundamental understanding of the self-assembly dynamics from heterocluster into NCs provides principles to control building block shape and guide target aggregation, which can further promote the design and construction of highly ordered cluster-assembled functional nanomaterials. [ABSTRACT FROM AUTHOR]

This review considers the use of fractal concepts to improve the development, fabrication, and characterisation of catalytic materials and supports. First, the theory of fractals is discussed, as well as how it can be used to better describe often highly complex catalytic materials and enhance structural characterisation via a variety of different methods, including gas sorption, mercury porosimetry, NMR, and several imaging modalities. The review then surveys various synthesis and fabrication methods that can be used to create catalytic materials that are fractals or possess fractal character. It then goes on to consider how the fractal properties of catalysts affect their performance, especially their overall activity, selectivity for desired products, and resistance to deactivation. Finally, this review describes how the optimum fractal catalyst material for a given reaction system can be designed on a computer. [ABSTRACT FROM AUTHOR]

Small‐angle X‐ray scattering (SAXS) is a widely used method for nanoparticle characterization. A common approach to analysing nanoparticles in solution by SAXS involves fitting the curve using a parametric model that relates real‐space parameters, such as nanoparticle size and electron density, to intensity values in reciprocal space. Selecting the optimal model is a crucial step in terms of analysis quality and can be time‐consuming and complex. Several studies have proposed effective methods, based on machine learning, to automate the model selection step. Deploying these methods in software intended for both researchers and industry raises several issues. The diversity of SAXS instrumentation requires assessment of the robustness of these methods on data from various machine configurations, involving significant variations in the q‐space ranges and highly variable signal‐to‐noise ratios (SNR) from one data set to another. In the case of laboratory instrumentation, data acquisition can be time‐consuming and there is no universal criterion for defining an optimal acquisition time. This paper presents an approach that revisits the nanoparticle model selection method proposed by Monge et al. [Acta Cryst. (2024), A80, 202–212], evaluating and enhancing its robustness on data from device configurations not seen during training, by expanding the data set used for training. The influence of SNR on predictor robustness is then assessed, improved, and used to propose a stopping criterion for optimizing the trade‐off between exposure time and data quality. [ABSTRACT FROM AUTHOR]

The present study explores the application of X-ray scattering, using synchrotron radiation, to assess the diffusive transport of nanomedicines in tumor on a chip devices fabricated by 3D stereolithography using a resin with high optical and X-ray transmittance. Unlike conventional methods that require fluorescent labeling of nanoparticles, potentially altering their in vitro and in vivo behavior, this approach enables the investigation of the transport properties for unlabeled nanoparticles. In particular, the results presented confirm the influence of the porosity of the extracellular matrix-like microenvironment, specifically Matrigel, on the diffusive transport of oligonucleotide-functionalized gold nanoparticles. The analysis of the scattering patterns allows to create 2D maps showing the nanoparticle distribution with high spatial resolution. The proposed approach demonstrates the potential for studying other factors involved in nanoparticle diffusion processes. By implementing X-ray scattering to track unmodified nanomedicines within extracellular matrix-like microenvironments, increasingly accurate models for evaluating and predicting therapeutics transport behaviors can be developed. [ABSTRACT FROM AUTHOR]

Tandem SAM-II/SAM-V riboswitch belongs to a class of riboswitches found in the marine bacterium 'Candidatus Pelagibacter ubique'. Previous studies have demonstrated that these riboswitches have the potential for digital modulation of gene expression at both the transcriptional and translational levels. In this study, we investigate the conformational changes in the tandem SAM-II/SAM-V riboswitch binding to S-adenosylmethionine (SAM) using selective 2′-hydroxyl acylation analyzed by the primer extension (SHAPE) assay, small-angle X-ray scattering (SAXS), and oligos depressing probing. Our findings reveal that the linker between SAM-II/SAM-V aptamers blocks the SAM response of the SAM-II domain. This result proposes a new mechanism for gene expression regulation, where the ligand-binding functions of tandem riboswitches can be selectively masked or released through a linker. [ABSTRACT FROM AUTHOR]

[Display omitted] Understanding the digestion of lipid-based pharmaceutical formulations and food systems is necessary for optimising drug and nutrient delivery and has been extensively studied in bulk emulsion systems using the pH-stat method [1]. However, this approach is not suitable for investigation of individual lipid droplets, in particular the interface where the lipase acts. Microfluidic approaches to study digestion at lipid-water interfaces using droplet trapping have been proposed, however the aqueous phase in that case washes over the interface presenting uncertainty over the stoichiometry of interactions [2]. The internal interface of a Janus-like droplet, containing distinct aqueous and lipid compartments, mimics the interface of a lipid droplet in aqueous solution with controlled stoichiometry [3]. Hence, it was hypothesised that the internal interface of Janus droplets can offer a precise way to study the enzymatic digestion of lipids formulations. Using microfluidic methods, Janus-like droplets were formed by coalescing emulsion droplets containing lipid formulation and pancreatic lipase. Polarised light microscopy (PLM) and in-situ small-angle X-ray scattering (SAXS) were used to investigate the droplets. PLM revealed the growth of an aligned inverse hexagonal phase (H 2), and with SAXS showed that this phase transformation and alignment resulted from enzymatic digestion. A subsequent partial transformation from H 2 to inverse bicontinuous cubic phase occurred when simulated intestinal fluid was used instead of Tris buffer. Suggesting that phospholipids and bile salts could diffuse across the internal interface to locally affect their surroundings. [ABSTRACT FROM AUTHOR]

Despite extensive research, the stabilization mechanism of mesomorphic isotactic polypropylene (iPP) at room temperature has not been elucidated completely. To address this issue, nanoscale structural information is indispensable. In this study, mesomorphic‐α phase transition is studied with synchrotron wide‐angle diffraction and small‐angle X‐ray scattering. It is found that during phase transition, the mobile amorphous content remained unchanged, while rigid amorphous fraction (RAF) decreased constantly, accompanied by an increase in long period. Assuming that the increase in long period is induced by the extension of the rigid amorphous coil (RAC), the thickness of RAF (RRAF) is estimated, which is found to be 2.2 nm. This value is greater than the length of b axis in α crystal cell, which can be the reason that folded‐chain iPP clusters in mesomorphic iPP cannot approach closer to form α crystal at room temperature. Besides, with RRAF, the thickness of smectic layer is estimated, which is found to be 0.9 nm. At this thickness, bulk‐free energy cannot compensate for the folded‐surface free energy, which can be the other reason that mesomorphic iPP chains cannot transit into α crystal at room temperature. The information obtained in this study is favorable for understanding the stabilization mechanism of mesomorphic iPP. [ABSTRACT FROM AUTHOR]

The process of transformation of the size and shape of platinum precursor particles at all stages of the preparation of supported Pt catalysts from precursor solutions to supported metal particles was studied using small-angle X-ray scattering (SAXS). It has been established that primary Pt-containing particles of different shapes and sizes can be obtained on the surface of supports depending on the acid–base properties of the supports and the presence of a stabilizer in the precursor solution. It has been shown that the size and shape of the primary precursor particles are decisive for the dispersion of supported platinum catalysts during their further preparation. [ABSTRACT FROM AUTHOR]

Using a 5 µm‐diameter X‐ray beam, we collected scanning X‐ray microdiffraction in both the small‐angle (SAXS) and the wide‐angle (WAXS) regimes from thin sections of fixed human brain tissue from Alzheimer's subjects. The intensity of scattering in the SAXS regime of these patterns exhibits essentially no correlation with the observed intensity in the WAXS regime, indicating that the structures responsible for these two portions of the diffraction patterns, which reflect different length scales, are distinct. SAXS scattering exhibits a power‐law behavior in which the log of intensity decreases linearly with the log of the scattering angle. The slope of the log–log curve is roughly proportional to the intensity in the SAXS regime and, surprisingly, inversely proportional to the intensity in the WAXS regime. We interpret these observations as being due to the presence of sub‐micrometre‐sized voids formed during dehydration of the fixed tissue. The SAXS intensity is due largely to scattering from these voids, while the WAXS intensity derives from the secondary structures of macromolecular material surrounding the voids. The ability to detect and map the presence of voids within thin sections of fixed tissue has the potential to provide novel information on the degradation of human brain tissue in neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

• NMR is the gold standard for determining the solution structures of G-quadruplexes. • Higher-order G-quadruplexes (xG4s) are often not amenable to characterization by NMR. • We show how NMR can be utilized in an integrative structural biology (ISB) approach to study xG4s. • We illustrate the ISB method and provide resources and best practices for those new to the field. Guanine-rich nucleic acids can form intramolecularly folded four-stranded structures known as G-quadruplexes (G4s). Traditionally, G4 research has focused on short, highly modified DNA or RNA sequences that form well-defined homogeneous compact structures. However, the existence of longer sequences with multiple G4 repeats, from proto-oncogene promoters to telomeres, suggests the potential for more complex higher-order structures with multiple G4 units that might offer selective drug-targeting sites for therapeutic development. These larger structures present significant challenges for structural characterization by traditional high-resolution methods like multi-dimensional NMR and X-ray crystallography due to their molecular complexity. To address this current challenge, we have developed an integrated structural biology (ISB) platform, combining experimental and computational methods to determine self-consistent molecular models of higher-order G4s (xG4s). Here we outline our ISB method using two recent examples from our lab, an extended c-Myc promoter and long human telomere G4 repeats, that highlights the utility and generality of our approach to characterizing biologically relevant xG4s. [ABSTRACT FROM AUTHOR]

The transcription factor Z4 (putzig) is one of the key proteins that determine the chromatin structure in Drosophila. Z4 is found at the boundaries of bands on polytene chromosomes, and the bands are currently thought to correlate with chromatin domains. Z4 is a component of a protein complex that additionally includes Chromator and BEAF-32, and a conserved domain is necessary to occur at the N end of Z4 to ensure its interaction with the two proteins. In this study, a zinc finger-associated domain (ZAD) domain was identified in Z4. The capability of dimerization was confirmed for the domain by biochemical methods. A dimer model of the domain was obtained using AlphaFold2, and the model structure was confirmed using small-angle X-ray scattering (SAXS). The dimer structure shows a fold typical of ZAD domains. [ABSTRACT FROM AUTHOR]

Over recent years, we have been living under a pandemic, caused by the rapid spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). One of the major virulence factors of Coronaviruses is the Non-structural protein 1 (Nsp1), known to suppress the host cells protein translation machinery, allowing the virus to produce its own proteins, propagate and invade new cells. To unveil the molecular mechanisms of SARS-CoV2 Nsp1, we have addressed its biochemical and biophysical properties in the presence of calcium, magnesium and manganese. Our findings indicate that the protein in solution is a monomer and binds to both manganese and calcium, with high affinity. Surprisingly, our results show that SARS-CoV2 Nsp1 alone displays metal-dependent endonucleolytic activity towards both RNA and DNA, regardless of the presence of host ribosome. These results show Nsp1 as new nuclease within the coronavirus family. Furthermore, the Nsp1 double variant R124A/K125A presents no nuclease activity for RNA, although it retains activity for DNA, suggesting distinct binding sites for DNA and RNA. Thus, we present for the first time, evidence that the activities of Nsp1 are modulated by the presence of different metals, which are proposed to play an important role during viral infection. This research contributes significantly to our understanding of the mechanisms of action of Coronaviruses. [ABSTRACT FROM AUTHOR]

The adenosine di-phosphate (ADP) ribosylation factor (Arf) small guanosine tri-phosphate (GTP)ases function as molecular switches to activate signaling cascades that control membrane organization in eukaryotic cells. In Arf1, the GDP/GTP switch does not occur spontaneously but requires guanine nucleotide exchange factors (GEFs) and membranes. Exchange involves massive conformational changes, including disruption of the core β-sheet. The mechanisms by which this energetically costly switch occurs remain to be elucidated. To probe the switch mechanism, we coupled pressure perturbation with nuclear magnetic resonance (NMR), Fourier Transform infra-red spectroscopy (FTIR), small-angle X-ray scattering (SAXS), fluorescence, and computation. Pressure induced the formation of a classical molten globule (MG) ensemble. Pressure also favored the GDP to GTP transition, providing strong support for the notion that the MG ensemble plays a functional role in the nucleotide switch. We propose that the MG ensemble allows for switching without the requirement for complete unfolding and may be recognized by GEFs. An MG-based switching mechanism could constitute a pervasive feature in Arfs and Arf-like GTPases, and more generally, the evolutionarily related (Ras-like small GTPases) Rags and Gα GTPases. [ABSTRACT FROM AUTHOR]

This study aimed to assess the applicability of solution-state 1H NMR for molecular-level characterization of siRNA-loaded lipid nanoparticles (LNP). Dilinoleylmethyl-4-dimethylaminobutyrate (DLin-MC3-DMA, MC3) was used as an ionizable lipid, and siRNA-loaded LNPs were prepared by pre-mixing and post-mixing methods. The pre-mixing method involved mixing an acidic solution containing siRNA with an ethanolic lipid solution using a microfluidic mixer. The pre-mixed LNP was prepared by dialyzing the mixed solution into the phosphate buffered saline (PBS, pH 7.4). The post-mixed LNP was prepared by mixing the siRNA solution with empty LNP in an acidic condition with and without ethanol, resulting in post-mixed LNP (A) and (B), respectively. Both pre-mixed and post-mixed LNPs formed LNP particles with an average diameter of approximately 50 nm. Moreover, the ratio of encapsulated siRNA to lipid content in each LNP particle remained constant regardless of the preparation method. However, small-angle X-ray scattering measurements indicated structural variations in the siRNA-MC3 stacked bilayer structure formed in the LNPs, depending on the preparation method. Solution-state 1H NMR analysis suggested that the siRNA was incorporated uniformly into the LNP core for pre-mixed LNP compared to post-mixed LNPs. In contrast, the post-mixed LNPs contained siRNA-empty regions with local enrichment of siRNA in the LNP core. This heterogeneity was more pronounced in post-mixed LNP (B) than in post-mixed LNP (A), suggesting that ethanol facilitated the homogeneous mixing of siRNA with LNP lipids. The silencing effect of each siRNA-loaded LNP was reduced in the order of pre-mixed LNP, post-mixed LNP (A), and post-mixed LNP (B). This suggested that the heterogeneity of the siRNA-loaded LNP could cause a reduction in the silencing effect of the incorporated siRNA inside LNPs. The present study highlighted that NMR-based characterization of siRNA-loaded LNP can reveal the molecular-level heterogeneity of siRNA-loaded LNP, which helps to optimize the preparation conditions of siRNA-loaded LNP formulations. [Display omitted] [ABSTRACT FROM AUTHOR]

An innovative dual‐thickness semi‐transparent beamstop designed to enhance the performance of small‐angle X‐ray scattering (SAXS) experiments is introduced. This design integrates two absorbers of differing thicknesses side by side into a single attenuator, known as a beamstop. Instead of completely stopping the direct beam, it attenuates it, allowing the SAXS detector to measure the transmitted beam through the sample. This approach achieves true synchronization in measuring both scattered and transmitted signals and effectively eliminates higher‐order harmonic contributions when determining the transmission light intensity through the sample. This facilitates and optimizes signal detection and background subtraction. This contribution details the theoretical basis and practical implementation of this solution at the SAXS station on the 1W2A beamline at the Beijing Synchrotron Radiation Facility. It also anticipates its application at other SAXS stations, including that at the forthcoming High Energy Photon Source, providing an effective solution for high‐precision SAXS experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydroxypropyl methylcellulose phthalate (HPMCP) is an enteric polymer that has been employed in drug delivery systems to delay the release of the encapsulated active pharmaceutical ingredients through its pH-responsive solubility change. This has been recently demonstrated as an effective means for delaying the drug release from gelatin/HPMCP hydrogels at gastric pH values. However, structural characteristics of HPMCP agglomeration in gelatin/HPMCP hydrogels is not well understood thus limiting further tailoring of their material properties. We investigated the multiscale structure of a gelatin/HPMCP hydrogel (1:1 by weight) between pH 2 and 6 at 37 °C, i.e. above the upper critical solution transition temperature of gelatin, using small-angle X-ray scattering and contrast-variation small-angle neutron scattering to understand the pH-responsive structure of HPMCP and the cross-correlation between gelatin and HPMCP. Agglomeration of HPMCP between pH 2 and 4 was evidenced by the formation of mass fractal structures, with a fractal dimension ranging from 1.5 to 2.7, comprising primary particles with a radius of gyration ranging from 70 to 140 Å. Blending with gelatin influenced the fractal structure of HPMCP and the primary particle size. Gelatin and HPMCP exhibited negative cross-correlation in all probed length scales and pH values, which was attributed to volume-exclusion interaction in a double-network-like solution architecture. [ABSTRACT FROM AUTHOR]

The red macroalgae Porphyra, commonly known as Nori, is widely used as food around the world due to its high nutrient content, including the significant abundance of colored phycobiliproteins (PBPs). Among these, R‐phycocyanin (R‐PC) stands out for its vibrant purple color and numerous bioactive properties, making it a valuable protein for the food industry. However, R‐PC's limited thermal stability necessitates alternative processing methods to preserve its color and bioactive properties. Our study aimed to investigate the in‐situ stability of oligomeric R‐PC under high pressure (HP) conditions (up to 4000 bar) using a combination of absorption, fluorescence, and small‐angle X‐ray scattering (SAXS) techniques. The unfolding of R‐PC is a multiphase process. Initially, low pressure induces conformational changes in the R‐PC oligomeric form (trimers). As pressure increases above 1600 bar, these trimers dissociate into monomers, and at pressures above 3000 bar, the subunits begin to unfold. When returned to atmospheric pressure, R‐PC partially refolds, retaining 50% of its original color absorbance. In contrast, heat treatment causes irreversible and detrimental effects on R‐PC color, highlighting the advantages of HP treatment in preserving both the color and bioactive properties of R‐PC compared to heat treatment. [ABSTRACT FROM AUTHOR]

In this work, the evolution of precipitates which formed under artificial aging in three kinds of cast Al–Li alloys was described by combining small-angle X-ray scattering (SAXS), transmission electron microscope (TEM) and differential Scanning Calorimeter (DSC). By analyzing SAXS data, the size, axial ratio and volume fraction of precipitates were characterized, and the effects of Cu and Mg on the evolution of δ′ and T1 particles under isothermal aging were quantitatively studied. The result shows that the precipitation of T1 competes with δ′ phase, leading to a significant increase in the volume fraction of precipitates in Cu-containing alloys. And the addition of Mg (0.5%) in Al–Li–Cu alloy induced the nucleation process of T1 phase, reduced the thickness and increased the number density of particles, and slightly increased the total volume fraction of precipitate, which was consistent with the results of TEM and DSC studies. Based on the revised formula, the relationship between the morphology of T1 particles and their shear stress on dislocations was described, thereby elucidating that magnesium atoms affect the mechanical properties of the alloy by regulating the morphology of T1 particles.

Abstract The present study explores the application of X-ray scattering, using synchrotron radiation, to assess the diffusive transport of nanomedicines in tumor on a chip devices fabricated by 3D stereolithography using a resin with high optical and X-ray transmittance. Unlike conventional methods that require fluorescent labeling of nanoparticles, potentially altering their in vitro and in vivo behavior, this approach enables the investigation of the transport properties for unlabeled nanoparticles. In particular, the results presented confirm the influence of the porosity of the extracellular matrix-like microenvironment, specifically Matrigel, on the diffusive transport of oligonucleotide-functionalized gold nanoparticles. The analysis of the scattering patterns allows to create 2D maps showing the nanoparticle distribution with high spatial resolution. The proposed approach demonstrates the potential for studying other factors involved in nanoparticle diffusion processes. By implementing X-ray scattering to track unmodified nanomedicines within extracellular matrix-like microenvironments, increasingly accurate models for evaluating and predicting therapeutics transport behaviors can be developed.

An innovative dual-thickness semi-transparent beamstop designed to enhance the performance of small-angle X-ray scattering (SAXS) experiments is introduced. This design integrates two absorbers of differing thicknesses side by side into a single attenuator, known as a beamstop. Instead of completely stopping the direct beam, it attenuates it, allowing the SAXS detector to measure the transmitted beam through the sample. This approach achieves true synchronization in measuring both scattered and transmitted signals and effectively eliminates higher-order harmonic contributions when determining the transmission light intensity through the sample. This facilitates and optimizes signal detection and background subtraction. This contribution details the theoretical basis and practical implementation of this solution at the SAXS station on the 1W2A beamline at the Beijing Synchrotron Radiation Facility. It also anticipates its application at other SAXS stations, including that at the forthcoming High Energy Photon Source, providing an effective solution for high-precision SAXS experiments.

Stimulated by informal conversations at the XVII International Small Angle Scattering (SAS) conference (Traverse City, 2017), an international team of experts undertook a round-robin exercise to produce a large dataset from proteins under standard solution conditions. These data were used to generate consensus SAS profiles for xylose isomerase, urate oxidase, xylanase, lysozyme and ribonuclease A. Here, we apply a new protocol using maximum likelihood with a larger number of the contributed datasets to generate improved consensus profiles. We investigate the fits of these profiles to predicted profiles from atomic coordinates that incorporate different models to account for the contribution to the scattering of water molecules of hydration surrounding proteins in solution. Programs using an implicit, shell-type hydration layer generally optimize fits to experimental data with the aid of two parameters that adjust the volume of the bulk solvent excluded by the protein and the contrast of the hydration layer. For these models, we found the error-weighted residual differences between the model and the experiment generally reflected the subsidiary maxima and minima in the consensus profiles that are determined by the size of the protein plus the hydration layer. By comparison, all-atom solute and solvent molecular dynamics (MD) simulations are without the benefit of adjustable parameters and, nonetheless, they yielded at least equally good fits with residual differences that are less reflective of the structure in the consensus profile. Further, where MD simulations accounted for the precise solvent composition of the experiment, specifically the inclusion of ions, the modelled radius of gyration values were significantly closer to the experiment. The power of adjustable parameters to mask real differences between a model and the structure present in solution is demonstrated by the results for the conformationally dynamic ribonuclease A and calculations with pseudo-experimental data. This study shows that, while methods invoking an implicit hydration layer have the unequivocal advantage of speed, care is needed to understand the influence of the adjustable parameters. All-atom solute and solvent MD simulations are slower but are less susceptible to false positives, and can account for thermal fluctuations in atomic positions, and more accurately represent the water molecules of hydration that contribute to the scattering profile.

[Display omitted] Mesophase dispersions are promising colloids for removing micropollutants from water. We hypothesized that the complex internal nanostructure and tunable lipid/water interface amounts play a crucial role in absorbed quantities. Modifications in interfacial organization within the particles while trapping the micropollutant is assumed. We formulated stable monolinolein-based dispersions with four types of mesophases (bicontinuous and micellar cubic, hexagonal, and fluid isotropic L 2) by varying dodecane contents. The absorption of bisphenol A by these dispersions from water was monitored using molecular spectroscopy. At equilibrium, absorbed quantities by mesophase dispersions were compared to unstructured dodecane/water miniemulsions for two bisphenol concentrations. Structural changes during bisphenol incorporation were identified using small-angle X-ray scattering. Lipid mesophase particles of submicron size showed greater bisphenol incorporation than dodecane/water miniemulsions, with cubosomes being most effective ones, absorbing twice as much as unstructured emulsions. Higher absorption levels are observed for more complex nanostructures with increased lipid/dodecane ratios. The incorporation of bisphenol affected the curvature of internal interfaces, potentially causing phase transitions and indicating that bisphenol settles at interfaces. Similar absorption levels in identical mesophases suggest a strong correlation between nano-structure and absorbed quantities. [ABSTRACT FROM AUTHOR]

Nano-scale dynamics of self-assembled therapeutics play a large role in their biological function. However, assessment of such dynamics remains absent from conventional pharmaceutical characterization. We hypothesize that time-resolved small-angle neutron scattering (TR-SANS) can reveal their kinetic properties. For lipid nanoparticles (LNP), limited molecular motion is important for avoiding degradation prior to entering cells while, intracellularly, enhanced molecular motion is then vital for effective endosomal escape. We propose TR-SANS for quantifying molecular exchange in LNPs and, therefore, enabling optimization of opposing molecular behaviors of a pharmaceutical in two distinct environments. We use TR-SANS in combination with traditional SANS and small-angle x-ray scattering (SAXS) to experimentally quantify nano-scale dynamics and provided unprecedented insight to molecular behavior of LNPs. LNPs have molecular exchange dynamics relevant to storage and delivery which can be captured using TR-SANS. Cholesterol exchanges on the time-scale of hours even at neutral pH. As pH drops below the effective pKa of the ionizable lipid, molecular exchange occurs faster. The results give insight into behavior enabling delivery and provide a quantifiable metric by which to compare formulations. Successful analysis of this multi-component system also expands the opportunities for using TR-SANS to characterize complex therapeutics.   [ABSTRACT FROM AUTHOR]

The functionality and efficiency of proteins within a biological membrane are highly dependent on both the membrane lipid composition and the physiochemical properties of the solution. Lipid mesophases are directly influenced by changes in temperature, pH, water content or due to individual properties of single lipids such as photoswitchability. In this work, we were able to induce light- and temperature-driven mesophase transitions in a model membrane system containing a mixture of 1,2-dipalmitoyl-phosphatidylcholine phospholipids and azobenzene amphiphiles. We observed reversible and reproducible transitions between the lamellar and Pn3m cubic phase after illuminating the sample for 5 min with light of 365 and 455 nm wavelengths, respectively, to switch between the cis and trans states of the azobenzene N=N double bond. These light-controlled mesophase transitions were found for mixed complexes with up to 20% content of the photosensitive molecule and at temperatures below the gel-to-liquid crystalline phase transition temperature of 33°C. Our results demonstrate the potential to design bespoke model systems to study the response of membrane lipids and proteins upon changes in mesophase without altering the environment and thus provide a possible basis for drug delivery systems.

The rise of antibiotic-resistant bacterial strains has become a critical health concern. According to the World Health Organization, the market introduction of new antibiotics is alarmingly sparse, underscoring the need for novel therapeutic targets. The LytR-CpsA-Psr (LCP) family of proteins, which facilitate the insertion of cell wall glycopolymers (CWGPs) like teichoic acids into peptidoglycan, has emerged as a promising target for antibiotic development. LCP proteins are crucial in bacterial adhesion and biofilm formation, making them attractive for disrupting these processes. This study investigated the structural and functional characteristics of the LCP domain of LytR from Streptococcus dysgalactiae subsp. dysgalactiae. The protein structure was solved by X-ray Crystallography at 2.80 A resolution. Small-angle X-ray scattering (SAXS) data were collected to examine potential conformational differences between the free and ligand-bound forms of the LytR LCP domain. Additionally, docking and molecular dynamics (MD) simulations were used to predict the interactions and conversion of ATP to ADP and AMP. Experimental validation of these predictions was performed using malachite green activity assays. The determined structure of the LCP domain revealed a fold highly similar to those of homologous proteins while SAXS data indicated potential conformational differences between the ligand-free and ligand-bound forms, suggesting a more compact conformation during catalysis, upon ligand binding. Docking and MD simulations predicted that the LytR LCP domain could interact with ADP and ATP and catalyze their conversion to AMP. These predictions were experimentally validated by malachite green activity assays, confirming the protein's functional versatility. The study provides significant insights into the structural features and functional capabilities of the LCP domain of LytR from S. dysgalactiae subsp. dysgalactiae. These findings pave the way for designing targeted therapies against antibiotic-resistant bacteria and offer strategies to disrupt bacterial biofilm formation. [ABSTRACT FROM AUTHOR]

Small‐angle X‐ray tensor tomography and the related wide‐angle X‐ray tensor tomography are X‐ray imaging techniques that tomographically reconstruct the anisotropic scattering density of extended samples. In previous studies, these methods have been used to image samples where the scattering density depends slowly on the direction of scattering, typically modeling the directionality, i.e. the texture, with a spherical harmonics expansion up until order ℓ = 8 or lower. This study investigates the performance of several established algorithms from small‐angle X‐ray tensor tomography on samples with a faster variation as a function of scattering direction and compares their expected and achieved performance. The various algorithms are tested using wide‐angle scattering data from an as‐drawn steel wire with known texture to establish the viability of the tensor tomography approach for such samples and to compare the performance of existing algorithms. [ABSTRACT FROM AUTHOR]

Due to the mechanical stability of PP layer, the PP/HDPE double-layer microporous membrane could be prepared at a higher heat-setting temperature than that of PE monolayer membrane. In this work, the effects of heat-setting temperature on the pore structure and properties of PP/HDPE double-layer membrane were studied. With the increase of heat-setting temperature from 120 °C to 130 °C, the length of connecting bridge crystal and crystallinity in the PE layer increase due to the melting of thin lamellae and the stability of connecting bridge structure during heat-setting. The corresponding air permeability, porosity, wettability of liquid electrolyte and mechanical property of the heat-set microporous membrane increase, exhibiting better electrochemical performance. However, when the heat-setting temperature is further increased to 140 °C, higher than the melting point of PE resin, some pores are closed since the lamellae and connecting bridges melt and shrink during heat-setting, resulting in a decrease of air permeability and porosity. In contrast, there is negligible change in the PP layer within the above heat-setting temperature region. This study successfully builds the relationship between the stable pore structure and property of microporous membrane during heat-setting, which is helpful to guide the production of high-performance PP/PE/PP lithium batteries separator. [ABSTRACT FROM AUTHOR]

In order to explore the changes in the performance of polyester fibers prepared by different processes under alkaline conditions, high tenacity (HT) polyester industrial fiber and fully drawn polyester yarn (FDY) of high speed spinning were selected for artificial accelerated aging tests in alkaline conditions at 85 °C. The mechanical properties of fibers were tested during the processes. Wide-angle X-ray diffraction, small-angle X-ray scattering and intrinsic viscosity were used to study the change in crystalline, lamellar structure and chemical structure of polyester fibers. The results showed that the changes in structure and properties of two polyester fibers in alkaline conditions can be divided into three stages. At the initial stage, the breaking strength and degree of orientation of the fibers first decreased significantly due to the effect of water and heat, while crystallinity remained constant. It was caused by the disorientation of amorphous orientated molecular chain segments in the frozen state, resulting in shrinkage. Then the decrease in breaking strength of fibers was slowed down, which was attributed to the breakage of amorphous molecular chains and the formation of a few new crystal structures. In the final stage of alkaline hydrolysis, the breaking strength of the fibers decreased significantly, while the crystallinity of fibers began to decline and the intrinsic viscosity reduced constantly, indicating that the breakage of amorphous molecular chain became the dominant factor. The alkaline hydrolysis reaction rate and the change degree of microstructure and mechanical property parameters of HT fibers were lower than those of FDY fibers, owing to the greater crystallinity and crystal size of HT fibers, which inhibited the erosion of water and OH-. As a result, HT fibers had a better alkaline hydrolysis resistance than FDY fibers. [ABSTRACT FROM AUTHOR]

The present study focuses on the utilization of a hydrogel consisting of gelatin methacrylate (GelMA) and polyvinyl alcohol (PVA) as a matrix for hosting the redox couple Fe(CN)63−/4−. The hydrogel exhibits a discernable thermopower (Src) of 3 mV K−1. The beneficial effect of the hydrogel microstructure on the mechanical robustness is demonstrated by small‐angle X‐ray scattering (SAXS). Moreover, the hydrogel is used to construct a 3D printed thermoelectric generator (TEG) consisting of eight p‐type thermoelectric legs, which exhibits commendable thermoelectric properties, including an open‐circuit voltage of 64 mV and a power density of 4.0 mW m−2 under a temperature gradient (ΔT) of 2.5 K. These findings demonstrate that 3D printing both enhances the quality of the interface between the hydrogel and electrode and provides a promising method for a more facile TEG fabrication process with the potential for further applications in low‐grade waste heat harvesting. [ABSTRACT FROM AUTHOR]

Many chemical reactions are accompanied by concerted phenomena, such as variance transition, structural changes, and particle formation. Various measurement techniques are employed to understand the whole picture of such concerted phenomena. A combination of small‐angle X‐ray scattering (SAXS), X‐ray diffraction (XRD), and X‐ray absorption fine structure (XAFS) is useful for studying concerted phenomena that occur, for example, inside rechargeable batteries. This combination can cover large lengths from 1 Å to several hundred nm. Operando measurements using this combination of methods can follow reactions during the charging and discharging of a rechargeable battery in a single experimental run. Fixed‐exit optics enable irradiation at the same point in a wide energy range. By employing 2D detectors for XRD and SAXS and using a quick XAFS technique, one can make the interval of each measurement sufficiently short to track various phenomena during charging and discharging. Here, an application of the system for alternating SAXS/XRD/XAFS measurements constructed in BL28XU, SPring‐8, Japan to the study of rechargeable batteries, is presented. [ABSTRACT FROM AUTHOR]

The particle sizes of main mineral compounds in the structure of lignite were determined using physical methods (SAXS, TEM, and XRD analysis) and chemical processes of selective dissolution. It has been shown that calcium and magnesium compounds in the structure of lignite were present in the form of small nanoparticles with sizes of about 10 nm. Particles consisting of aluminum and iron compounds had larger sizes of about 20–35 nm. Silica-containing particles in the structure of lignite had sizes of 100 nm or greater. [ABSTRACT FROM AUTHOR]

The molecular structures of surfactants play a pivotal role in influencing their self‐assembly behaviors. In this work, using simulations and experiments, an unconventional hierarchically layered structure in the didodecyldimethylammonium bromide (DDAB)/water binary system: lamellae‐in‐lamellae is revealed, a new self‐assembly structure in surfactant system. This self‐assembly structure refers to a lamellar structure with a shorter periodic length (inner lamellae) embedded in a lamellar phase with a longer periodic length (outer lamellae). The normal vectors of these two lamellar regions orient perpendicularly. In addition, it is observed that this lamellar‐in‐lamellar phase disappears when the two tails of the cationic surfactants become longer. The formation of the lamellar‐in‐lamellar architecture arises from multiple interacting factors. The key element is that the short tails of the DDAB surfactants enhance hydrophilicity and rigidity, which facilitates the formation of the inner lamellae. Moreover, the lateral monolayer of the inner lamellae provides shielding from the water and prompts the formation of the outer lamellae. These findings indicate that molecular structures and flexibility can profoundly redirect the hierarchical self‐assembly behaviors in amphiphilic systems. More broadly, this work presents a new strategy to deliberately program hierarchical nanomaterials by designing specific surfactant molecules to act as tunable scaffolds, reactors, and carriers. [ABSTRACT FROM AUTHOR]

The Bifidobacterium bifidum SAM-VI riboswitch undergoes dynamic conformational changes that modulate downstream gene expression. Traditional structural methods such as crystallography capture the bound conformation at high resolution, and additional efforts would reveal details from the dynamic transition. Here, we revealed a transcription-dependent conformation model for Bifidobacterium bifidum SAM-VI riboswitch. In this study, we combine small-angle X-ray scattering, chemical probing, and isothermal titration calorimetry to unveil the ligand-binding properties and conformational changes of the Bifidobacterium bifidum SAM-VI riboswitch and its variants. Our results suggest that the SAM-VI riboswitch contains a pre-organized ligand-binding pocket and stabilizes into the bound conformation upon binding to SAM. Whether the P1 stem formed and variations in length critically influence the conformational dynamics of the SAM-VI riboswitch. Our study provides the basis for artificially engineering the riboswitch by manipulating its peripheral sequences without modifying the SAM-binding core. [ABSTRACT FROM AUTHOR]

This paper reports a novel α-gel formulation technology referred to as polymer complexed lamella (PCL) that uses hydroxypropyl methyl cellulose (HPMC) and glycerol. The PCL method suppressed lipid crystallization even after drying. This effect was maximized by the addition of HPMC and glycerol at high temperature. HPMC and lipids coexisted when mixed at high temperature, which decreased the mobility of HPMC, an effect that was enhanced by the strong interaction of glycerol with HPMC. These results indicate that mixing of HPMC with glycerol directly regulates the lipid structure and suppresses crystallization. PCL also maintained the effect of occlusion related to the moisturization of skin, even if the membrane was repeatedly bent such as in facial expressions. [ABSTRACT FROM AUTHOR]

Conserved tryptophan residues are critical for the structure and the stability of β/γ‐crystallin in the lenses of vertebrates. During aging, in which the lenses are continuously exposed to ultraviolet irradiation and other environmental stresses, oxidation of tryptophan residues in β/γ‐crystallin is triggered and impacts the lens proteins to varying degrees. Kynurenine derivatives, formed by oxidation of tryptophan, accumulate, resulting in destabilization and insolubilization of β/γ‐crystallin, which correlates with age‐related cataract formation. To understand the contribution of tryptophan modification on the structure and stability of human βB2‐crystallin, five tryptophan residues were mutated to phenylalanine considering its similarity in structure and hydrophilicity to kynurenine. Among all mutants, W59F and W151F altered the stability and homo‐oligomerization of βB2‐crystallin—W59F promoted tetramerization whereas W151F blocked oligomerization. Most W59F dimers transformed into tetramer in a month, and the separated dimer and tetramer of W59F demonstrated different structures and hydrophobicity, implying that the biochemical properties of βB2‐crystallin vary over time. By using SAXS, we found that the dimer of βB2‐crystallin in solution resembled the lattice βB1‐crystallin dimer (face‐en‐face), whereas the tetramer of βB2‐crystallin in solution resembled its lattice tetramer (domain‐swapped). Our results suggest that homo‐oligomerization of βB2‐crystallin includes potential inter‐subunit reactions, such as dissociation, unfolding, and re‐formation of the dimers into a tetramer in solution. The W>F mutants are useful in studying different folding states of βB2‐crystallin in lens. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of the impact of quenching roll speed on enhancing the low-temperature toughness of a low-carbon copper-containing steel. The microstructure characteristics, such as the prior austenite grains, and the distribution and volume fraction of precipitates, are observed using optical microscopy, scanning electron microscopy, transmission electron microscopy, and small-angle scattering X-ray. The results show that a decrease in the quenching roller speed (2 m/min) contributes to the achievement of more excellent low-temperature toughness (the average value is 232 J), although the prior austenite grains exhibit a relatively larger size in this case. The tempering treatment results in the precipitation of a large amount of 9R-type Cu-rich particles, regardless of the quenching roller speed. Reducing the quenching roller speed contributes to the increase in the volume fraction of Cu-rich particles, which is considered to be the main factor contributing to the achievement of excellent low-temperature toughness. [ABSTRACT FROM AUTHOR]

[Display omitted] Imogolite nanotubes (INTs) are unique anisometric particles with monodisperse nanometric diameters. Aluminogermanate double-walled INTs (Ge-DWINTs) are obtained with variable aspect ratios by controlling the synthesis conditions. It thus appears as an interesting model system to investigate how aspect ratio and ionic valence influence the colloidal behavior of highly anisometric rods. The nanotubes were synthesized by hydrothermal treatment for 5 or 20 days to modify the aspect ratio while the electrostatic interactions were investigated by comparing the colloidal stability in symmetric and asymmetric electrolytes. The phase behavior and their related microstructure were determined by optical observations and small-angle X-ray scattering measurements, coupled with interparticle distance modelling. We revealed that colloidal suspensions of Ge-DWINTs prepared in NaCl are guided by repulsive double layer forces, undergoing different liquid crystal phase transitions before stiffen into a glass-like state. We found that the microstructure can be rationalized by taking into account the anisometric nature of the particles. By contrast, dispersions prepared with asymmetric electrolytes are governed by strong attractive forces and thus form space-filling gels containing large nanotubes aggregates. [ABSTRACT FROM AUTHOR]

Patients with type 1 diabetes mellitus who are dependent on an external supply of insulin develop insulin-derived amyloidosis at the sites of insulin injection. A major component of these plaques is identified as full-length insulin consisting of the two chains A and B. While there have been several reports that characterize insulin misfolding and the biophysical properties of the fibrils, atomic-level information on the insulin fibril architecture remains elusive. We present here an atomic resolution structure of a monomorphic insulin amyloid fibril that has been determined using magic angle spinning solid-state NMR spectroscopy. The structure of the insulin monomer yields a U-shaped fold in which the two chains A and B are arranged in parallel to each other and are oriented perpendicular to the fibril axis. Each chain contains two ß-strands. We identify two hydrophobic clusters that together with the three preserved disulfide bridges define the amyloid core structure. The surface of the monomeric amyloid unit cell is hydrophobic implicating a potential dimerization and oligomerization interface for the assembly of several protofilaments in the mature fibril. The structure provides a starting point for the development of drugs that bind to the fibril surface and disrupt secondary nucleation as well as for other therapeutic approaches to attenuate insulin aggregation. [ABSTRACT FROM AUTHOR]

The new hybrid composite materials for PEM fuel cell were synthesized by the UV polymerization of acrylic monomers (acrylonitrile, acrylic acid, ethylene glycol dimethacrylate) and a sulfo aromatic monomer, i.e., sodium styrene sulfonate, and the tetraethoxysilane/3-methacryloxypropyltrimethoxysilane-based sol–gel system. By means of X-ray spectroscopy, the fractal structure of the obtained materials was characterized. Proton conductivity and viscoelasticity of the obtained materials were determined depending on the content of the inorganic component in nanocomposites. Based on impedance studies, an equivalent scheme is proposed that successfully describes the proton conductivity in the synthesized composite's electrolyte membranes. [ABSTRACT FROM AUTHOR]

The use of synthetic and natural resins in the fixation of organomineral matter for further studies is common, e.g. in the micromorphological study of soils, since the procedure of making thin sections includes the impregnation of the sample with the filling materials (resins). At the same time, their effect on the soil structure remains poorly known. In this article, an experiment to study the impact of synthetic and natural resins on the nano- and microstructure of soil during impregnation is considered. First data on the characteristics of resins frequently used in laboratories, as well as on their effects on the structure of soil samples have been obtained with small-angle X-ray scattering and computed tomography techniques. The X-ray transparency of fixing materials was detected. Subsequent impregnation of the AU horizon fraction from Haplic Chernozems of Kursk oblast by fixing materials allowed establishing their influence on the change in size of soil nanostructural heterogeneities. The experiment with different horizons of Protosalic Solonetz attests to a decrease in the size of nanoheterogeneities with depth in the impregnated soil as compared with that in the native soil. At the microlevel, a decrease in microporosity within the first percent after polymerization of the fixing material has been proved. As a result of studies of nanoheterogeneities in the soil, scanning parameters have been experimentally selected at the BioSAS station of the Kurchatov's synchrotron radiation source. The nanostructure of soil core samples and separate fractions has been studied for the first time at this station. The above results can be used in sample preparation and further analysis of organomineral objects (soils, rocks) for a number of studies that require fixation of the substance structure at different dimensional levels. [ABSTRACT FROM AUTHOR]

Oil-gas two phase wax deposition is a fairly common and open-ended question in flow assurance of multiphase transportation pipelines. This paper investigated the two main aspects of oil-gas two phase wax deposition layer: apparent thickness and crystal structure characteristics. A typical highly paraffinic oil in Bohai Sea, China, was used as the experimental material to investigate the wax deposition thickness in oil-gas two phase under the influence of different oil temperatures, superficial gas/liquid phase velocities and gas-oil ratios by using multiphase flow loop experimental device. Just as in the classical theory of wax molecular diffusion, it showed that wax deposition thickness of oil-gas two phase increased with increasing oil temperature. Analysis of the impact of different superficial phase velocities found that the actual liquid flow heat transfer and shear stripping was the gas phase dominant mechanisms determining wax deposit thickness. In addition, the crystal structure of the wax deposition layer was characterized with the help of small-angle X-ray scattering (SAXS) for different circumferential positions, flow rates and gas-oil ratios. The bottom deposition layer had a complex crystal structure and high hardness, which were subject to change over flow rate variations. Furthermore, the SAXS results provided evidence that the indirect effect of the actual liquid velocity modified by the gas phase was the main mechanism. Our study of the effect of gas phase on the wax deposition of oil-gas two phase will help shed light onto the mechanism by which this important process occurs. Our findings address a very urgent need in the field of wax deposition of highly paraffinic oil to understand the flow security of oilgas two phase that occurs easily in multiphase field pipelines. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the impact of repeated exposure to hyperbaric hydrogen (90 MPa; 30 °C) and pressure release on the microstructure and mechanical behavior of PA11. Samples were analyzed after 1, 2, 5 and 10 cycles, by SAXS, WAXS, DMA, DSC, and a series of mechanical tests with variable triaxiality ratio. The most visible change in the residual state after desorption was a stiffening of the amorphous phase. It mainly originated from the first cycle, especially the first pressurization. The crystalline phase was slightly affected and no evidence of nano-voiding was brought in the residual state up to 10 cycles. Similar analyses were conducted during the first cycle's desorption transient. They showed a reversible plasticizing effect and a trend of nano-voiding vanishing after desorption but might promote damage upon further triaxial loading.

BTB (bric-a-brack, Tramtrack, and broad complex) is a diverse group of protein-protein interaction domains found within metazoan proteins. Transcription factors contain a dimerizing BTB subtype with a characteristic N-terminal extension. The Tramtrack group (TTK) is a distinct type of BTB domain, which can multimerize. Single-particle cryo-EM microscopy revealed that the TTK-type BTB domains assemble into a hexameric structure consisting of three canonical BTB dimers connected through a previously uncharacterized interface. We demonstrated that the TTK-type BTB domains are found only in Arthropods and have undergone lineage-specific expansion in modern insects. The Drosophila genome encodes 24 transcription factors with TTK-type BTB domains, whereas only four have non-TTK-type BTB domains. Yeast two-hybrid analysis revealed that the TTK-type BTB domains have an unusually broad potential for heteromeric associations presumably through a dimer-dimer interaction interface. Thus, the TTK-type BTB domains are a structurally and functionally distinct group of protein domains specific to Arthropodan transcription factors.