Structural Studies Research Articles

Design, synthesis and structural study of novel acetamidobenzanilide derivatives

Design, synthesis and structural study of novel acetamidobenzanilide derivatives

Liquid-Phase NMR of Humic and Fulvic Acids.

Present review focuses on the most recent advances in the NMR of the coal-derived humic and fulvic acids, covering exclusively the results of the liquid-phase NMR and leaving apart an overwhelming amount of publications dealing with the solid-state NMR investigations in this field (the latter are comprehensively reviewed elsewhere). Owing to the complexity of humic and fulvic acids together with other coal-derived products, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of humic and fulvic acids by means of NMR revealed characteristic functional groups of their composition together with spectral regions in which they resonate. Quantitative 1H and 13C NMR spectra characterize aromatic and saturated carbons spread over many structural moieties, which provides a solid guideline into molecular structure of humic and fulvic acids together with parent coal-derived products. Nowadays, quantitative 13C NMR measurements yield information about a variety of structural parameters such as functional group distribution, aromaticity, degree of condensation of aromatic rings, and medium chain lengths together with many other more specific parameters. The structural NMR studies of the coal-derived products are developing on a background of a marked progress in experimental and computational NMR. Discussed in the present review are the most recent advances in the liquid-state NMR studies of the coal-derived humic and fulvic acids together with their processing products.

Computational engineering of water-soluble human potassium ion channels through QTY transformation.

Transmembrane potassium ion channels are crucial for ion transport, metabolism, and signaling, and serve as promising targets for anti-cancer therapies. However, their hydrophobic transmembrane nature requires detergents, posing a major bottleneck for experimental handling. In this paper, we present a structural bioinformatics study of six experimentally determined and twelve modeled potassium channel structures, in which hydrophobic amino acids (L, I/V, and F) were systematically replaced with neutral hydrophilic ones (Q, T, and Y), making the proteins more water-soluble. QTY (computationally predicted) and native (experimental and repredicted) variants show remarkable structural similarity (RMSD: ~0.50 Å - ~2.14 Å) despite significant sequence differences. QTY variants, both rigid and refined with MD simulations, maintain comparable to native variants stability, solvent-accessible surface area (SASA), and ionic, aromatic, and van der Waals interactions but differ in the grand average of hydropathy (GRAVY), solubility, and hydrophobic contacts. Overall, our study presents a computational approach for designing hydrophilic potassium ion channels while maintaining the native global structure that could potentially simplify their practical use by eliminating the need for detergents.

Analysis of Synergistic Changes in PM2.5 and O3 Concentrations Based on Structural Equation Model Study

Given the increasing importance of effectively identifying synergistic changes between PM2.5 and O3 and comprehensively analyzing their impact on air quality management in China, we employ the Sen+Mann–Kendall (Sen+M-K) trend test in this study to examine the temporal and spatial variation trends of PM2.5 and O3 in the Yangtze River Delta (YRD), from 2003 to 2020. We identified the regions where these pollutants exhibited synergistic changes and established the pathways between the pollutants and their potential drivers, using geographically weighted random forest algorithms and structural equation modeling. The study results revealed as follows: (1) Overall, the PM2.5 concentrations show a decreasing trend, while the O3 concentrations exhibit an increasing trend, in the YRD. Analysis of the combined trends indicates that approximately 95% of the area displays opposing trends for PM2.5 and O3, with only about 4% in the southern region showing synergistic trends for both pollutants. (2) Drought and the average temperature are the main drivers of the changes in PM2.5 and O3 concentrations in areas experiencing synergistic changes. Their combined effects alleviate the aggregation of PM2.5 and reduce the formation of VOCs, indirectly reducing the generation of pollutants. The negative effect of the average temperature on the O3 concentration may indicate the existence of nonlinear effects and complex interaction effects between the drivers. NOx and VOCs play important dual roles in the generation and conversion of pollutants, although their overall impact is smaller than meteorological factors. They produce significant indirect effects through their interaction with meteorological and other human factors, further affecting the concentrations of PM2.5 and O3. In areas without coordinated changes, the main impact of meteorological factors remains unchanged, and the relationship between the two anthropogenic emission sources and their effects on PM2.5 and O3 are complex, with different directions and levels involved. This study provides detailed insights into the drivers of air quality changes in the YRD and offers a scientific basis for environmental management authorities to develop more comprehensive and targeted strategies for balancing the control of PM2.5 and O3 pollution.

Structural insights into thyroid hormone receptors.

Thyroid hormone receptors (TRs) are essential components of the endocrine system, mediating the cellular effects of thyroid hormones. The two TR genes, THRA and THRB, encode four isoforms, with TRα1 and TRβ1 being the most prevalent. TRs are ligand-dependent transcription factors and members of the nuclear receptor superfamily, indispensable for human growth, development and metabolism. Dysfunctional TR signaling can lead to conditions like resistance to thyroid hormone (RTH) syndrome, thyroid cancer, and metabolic disorders. Structurally, TRs comprise several domains: a variable N-terminal domain, a conserved DNA-binding domain, and a ligand-binding domain that mediates interaction with hormones and transcriptional coregulators. TRs predominantly function as heterodimers with the retinoid X receptor (RXR), binding to thyroid hormone response elements (TREs) in target genes to regulate their transcription. This review examines the structural studies on TRs, primarily performed through X-ray crystallography, that have provided detailed insights into TR functions, including DNA recognition, ligand binding, and coregulator interactions. We also discuss how these findings have deepened our understanding of TR mechanisms and contributed to the interpretation of pathogenic mutations.

Refolding dynamics and immunoinformatic insights into Vibrio cholerae OmpA, OmpK, and OmpV for vaccine applications.

OmpA, OmpK, and OmpV are crucial for the pathogenesis of Vibrio cholerae, functioning within the bacterium's outer membrane; they present significant potential as candidates for vaccine development. Due to their intrinsic β-sheet richness, these OMPs tend to form inclusion bodies whenever overexpression is attempted. To achieve a native-like structure, detergents can be utilized during the refolding of OMPs from inclusion bodies. The impact of different detergents is examined on the renaturation of these OMPs, specifically non-ionic and zwitterionic detergents. The findings provide valuable insights into detergent selection, with LDAO and DDM emerging as the best protein refolding agents, facilitating successful structural and functional studies of these OMPs. Furthermore, using immunoinformatics it is established that OmpA, OmpK, and OmpV carry B- and T-cell epitopes in their exposed extracellular regions. The presence of immunodominant regions makes it easier to employ these proteins as vaccine candidates as they are stable, non-allergenic, and likely to stimulate successful innate and active immune responses. Overall, with all three OMPs harboring numerous immunogenic epitopes, they can be employed in subunit vaccines against Vibrio spp. and contribute to the development of diagnostic tools for effective disease mitigation.

High-throughput structural screening and property study of noncentrosymmetric superconductors in Th-based ZrNiAl-like compounds

Noncentrosymmetric superconductors (NCSs) are emerging as potential materials for the investigation of nontraditional phenomena, including both the presence of a spin-singlet pairing configuration and the occurrence of a spin-triplet pairing configuration, as well as the manifestation of topological superconductivity. In this work, we constructed a high-throughput theoretical design and performed a computational screening of Th-based NCSs with ZrNiAl-like structures based on the first principles method. Through systematic stability evaluations, we expanded the range of Th-based ZrNiAl-like compounds with superior stability to 45 materials. In this group of substances, we have pinpointed 17 prospective entities exhibiting notable band separation in the vicinity of the Fermi level. Electron–phonon coupling calculations indicated that 14 of these compounds are superconducting. By performing an analysis of electronic properties, we proposed that ThAlRu and ThAlOs are two promising NCSs in this family. This work may aid in the exploration of the design and synthesis of Th-based ZrNiAl-like materials, leading to the discovery of more NCSs with unique superconducting properties.

Modification of Poly(3-Hydroxybutyrate) with a Linear Polyurethane Modifier and Organic Nanofiller—Preparation and Structure–Property Relationship

The growing demand for products made of polymeric materials, including the commonly used polypropylene (PP), is accompanied by the problem of storing and disposing of non-biodegradable waste, increasing greenhouse gas emissions, climate change and the creation of toxic products that constitute a health hazard of all living organisms. Moreover, most of the synthetic polymers used are made from petrochemical feedstocks from non-renewable resources. The use of petrochemical raw materials also causes degradation of the natural environment. A potential solution to these problems is the use of biopolymers. Biopolymers include biodegradable or biosynthesizable polymers, i.e., obtained from renewable sources or produced synthetically but from raw materials of natural origin. One of them is the poly(3-hydroxybutyrate) (P3HB) biopolymer, whose properties are comparable to PP. Unfortunately, it is necessary to modify its properties to improve its processing and operational properties. In the work, hybrid polymer nanobiocomposites based on P3HB, with the addition of chain, uncross-linked polyurethane (PU) and layered aluminosilicate modified with organic salts (Cloisite®30B) were produced by extrusion process. The introduction of PU and Cloisite®30B to the polymer matrix (P3HB) influenced the processing parameters beneficially and resulted in a decrease in the extrusion temperature of more than 10 °C. The influence of the simultaneous addition of a constant amount of PU (10 m/m%) and the different amounts of nanoadditives (1, 2 and 3 m/m%) on the compatibility, morphology and static mechanical properties of the resulted nanobiocomposites were examined. The component interactions by Fourier transformation infrared spectroscopy (FTIR) analysis, nano- and microscale structure studies using small-angle X-ray scattering (SAXS) and morphology by scanning electron microscopy (SEM) were carried out, and the hardness and tensile strength of the obtained polymer nanobiocomposites were determined. FTIR analysis identified the compatibility of the polyester matrix, PU, and organomodified montmorillonite, the greatest being 3 m/m% Cloisite30B content. The addition of PU to the polyester elasticizes the material and decreases the material’s strength and ductility. The presence of nanoclay enhanced the mechanical properties of nanobiocomposites. The resulting nanobiocomposites can be used in the production of short-life materials applied in gardening or agriculture.

Al Islands on Si(111): Growth Temperature, Morphology and Strain

The comprehensive structural studies of thin island Al films with a thickness of 20–50 nm deposited by magnetron sputtering on Si(111) substrates in an argon plasma at a pressure of 6*10–3 mbar and a temperature from 20 to 500°C are presented. Studies of the morphology and microstructure of the films were carried out using XRD, SEM, EDS and TEM methods. It has been found that most of the islands are Al {001} and Al {111} crystallites with lateral sizes of 10–100 nm, differently conjugated with Si(111) substrate. At room temperature of the substrate, only Al {001} crystallites are epitaxially formed on it. The Al {111} crystallites epitaxially grown on the substrate dominate as the substrate temperature increases about 400°C. The influence of the temperature of the Si(111) substrate on the process of epitaxial growth of crystallites, the dynamics of their shape and structural perfection is shown. It has been found that crystallites epitaxially connected to the substrate experience deformation ε = 7 × 10–3 and ε = –2 × 10–3 for Al {001} and Al {111}, respectively. It has been shown that for thin island Al films on Si(111), the dependence of the number of crystallization centers and the particle growth rate on the supercooling temperature is consistent with the band model of crystallization. At the same time, a shift in the characteristic temperatures for the zone boundaries is observed due to the properties of the substrate. This must be taken into account when engineering the surface morphology and structural perfection of crystallites in Al island magnetron films.

Examining the Influence of Demographic Factors on Problem-Solving Ability: A Study of Gender, Family Structure, and School Characteristics

Problem-solving involves overcoming obstacles that hinder goal attainment and finding optimal solutions to issues. This ability empowers learners to address challenges they encounter effectively. Consequently, problem-solving has become one of the most crucial 21st-century skills for better future adjustment in a complex society. This paper examines gender, family type, school type, and locality as correlates of problem-solving ability. The researchers conducted descriptive research with 1,200 secondary school students from the Thoubal district of Manipur. They used the Problem-solving Ability Test (PSAT), which they constructed based on five dimensions of problem-solving ability, to collect data. The findings reveal that male students significantly outperformed female students in the PSAT. Although students from joint families performed slightly better than those from nuclear families, the difference was insignificant. Additionally, students in private schools significantly outperformed those in government schools. Moreover, students from urban schools substantially outperformed those in rural schools on the PSAT.

Quantitative assessment of neurodevelopmental maturation: a comprehensive systematic literature review of artificial intelligence-based brain age prediction in pediatric populations

IntroductionOver the past few decades, numerous researchers have explored the application of machine learning for assessing children’s neurological development. Developmental changes in the brain could be utilized to gauge the alignment of its maturation status with the child’s chronological age. AI is trained to analyze changes in different modalities and estimate the brain age of subjects. Disparities between the predicted and chronological age can be viewed as a biomarker for a pathological condition. This literature review aims to illuminate research studies that have employed AI to predict children’s brain age.MethodsThe inclusion criteria for this study were predicting brain age via AI in healthy children up to 12 years. The search term was centered around the keywords “pediatric,” “artificial intelligence,” and “brain age” and was utilized in PubMed and IEEEXplore. The selected literature was then examined for information on data acquisition methods, the age range of the study population, pre-processing, methods and AI techniques utilized, the quality of the respective techniques, model explanation, and clinical applications.ResultsFifty one publications from 2012 to 2024 were included in the analysis. The primary modality of data acquisition was MRI, followed by EEG. Structural and functional MRI-based studies commonly used publicly available datasets, while EEG-based studies typically relied on self-recruitment. Many studies utilized pre-processing pipelines provided by toolkit suites, particularly in MRI-based research. The most frequently used model type was kernel-based learning algorithms, followed by convolutional neural networks. Overall, prediction accuracy may improve when multiple acquisition modalities are used, but comparing studies is challenging. In EEG, the prediction error decreases as the number of electrodes increases. Approximately one-third of the studies used explainable artificial intelligence methods to explain the model and chosen parameters. However, there is a significant clinical translation gap as no study has tested their model in a clinical routine setting.DiscussionFurther research should test on external datasets and include low-quality routine images for MRI. T2-weighted MRI was underrepresented. Furthermore, different kernel types should be compared on the same dataset. Implementing modern model architectures, such as convolutional neural networks, should be the next step in EEG-based research studies.

Structural basis of MICAL autoinhibition.

MICAL proteins play a crucial role in cellular dynamics by binding and disassembling actin filaments, impacting processes like axon guidance, cytokinesis, and cell morphology. Their cellular activity is tightly controlled, as dysregulation can lead to detrimental effects on cellular morphology. Although previous studies have suggested that MICALs are autoinhibited, and require Rab proteins to become active, the detailed molecular mechanisms remained unclear. Here, we report the cryo-EM structure of human MICAL1 at a nominal resolution of 3.1 Å. Structural analyses, alongside biochemical and functional studies, show that MICAL1 autoinhibition is mediated by an intramolecular interaction between its N-terminal catalytic and C-terminal coiled-coil domains, blocking F-actin interaction. Moreover, we demonstrate that allosteric changes in the coiled-coil domain and the binding of the tripartite assembly of CH-L2α1-LIM domains to the coiled-coil domain are crucial for MICAL activation and autoinhibition. These mechanisms appear to be evolutionarily conserved, suggesting a potential universality across the MICAL family.

Charge transfer induced phase transition in Li2MnO3 at high pressure

Efficient and better energy storage materials are of utmost technological importance to reduce energy dependence on the fossil fuels. Li2MnO3is one such material having potential to meet most of the requirements for energy storage. This material has been synthesized using solid state synthesis route. High pressure structural and vibrational studies on this material have been carried out upto ∼22 and 26 GPa respectively. These investigations show occurrence of a hitherto unknown second order phase transition to a new low symmetry phase whose symmetry is constrained to be monoclinic with space group P21/n at pressure of ∼2.3 GPa in Li2MnO3. The bulk modulus and its derivative determined by fitting theP-Vdata with third order Birch-Murnaghan equation of state are 113.3 ± 13.1 GPa and 4.1 ± 1.2 respectively. Mode Grüneisen parameter calculated for all the Raman modes show positive values which indicates the absence of any soft mode in this material. A microscopic mechanism based on bond-charge transfer is invoked and applied to understand the spectroscopic changes occurring in this material which also manifests second order structural phase transition. Enhancement in covalent character of Li-O bonds in the Li-O polyhedra is inferred based on the spectroscopic observation and above mechanism.

Morphological and structural analysis of monodispersive silica nanoparticles fabricated by stober method for self-cleaning applications

Abstract In this work, silica nanoparticles have been synthesized via the Stober process on a p-type silicon substrate by spin coating method. Structural and morphological studies have been carried out by x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Microstructural analysis by Raman spectroscopy displays a prominent peak at 524 cm−1 which corresponds to crystalline silicon. Further, the elemental study by using energy dispersive x-ray spectroscopy (EDX) confirms the presence of silica with no other impurities. Besides, the wettability property has been studied by contact angle measurement and found to be around 130° for the 6-layer coated thin film which is quasi-super-hydrophobic. The wettability results obtained signify promising properties for the development of self-cleaning devices and applications.

The Aesthetics of Jordanian Place in the Novel The Flood Notebooks by Jordanian Writer Samiha Khrais

This research studied and analyzed the aesthetics of the Jordanian place in the novel The Flood Notebooks by the Jordanian writer Samiha Khrais. The importance of this novel lies in the fact that it is a social-historical novel that depicts a Jordanian place in the 1930s. Its writer was able to combine truth with imagination to present an artistic work whose events are derived from history, yet it is not a historical document; rather, it is a work of art, and the writer excelled in its construction. The two researchers studied the place in this novel within the framework of specific dualities of both the historical and contemporary place, the open and closed place, and the real and symbolic place. The study of duality, or opposites, is at the heart of the structural studies of meaning, which took as its starting point the duality of phenomena, claiming that it is a characteristic of human thought. However, the present study will not stop at these dualities alone; rather, it will benefit from the current semiotics due to the interest they provide in structure and meaning and the ability to interpret texts according to the context in which they appear.

Novel Nordaucane Sesquiterpenoid and Sesquiterpene Lactone From Laserpitium Species: Isolation, Structure Elucidation, InVitro, InVivo, and In Silico Evaluation as Anticancer Agents.

This study explores the cytotoxic activity-guided isolation of the underground parts of Laserpitium hispidum M. Bieb and Laserpitium petrophilum Boiss. & Heldr., which have not been previously investigated. The aim is to isolate and evaluate bioactive compounds from Laserpitium L. species with anticancer potential. This study involves bioactivity-guided isolation and structural studies of the pure compounds utilizing NMR, UV-Vis, IR spectroscopies, and HRMS. The cytotoxic activity of the isolated compounds was evaluated invitro and invivo, whereas molecular modeling, docking, and ADME predictions were conducted using Schrödinger software. The study isolated phenylpropanoids (laserine (1), latifolone (2), myristicin (3)), sterol (stigmasterol (4)), polyenes (falcarindiol (5)), sesquiterpene lactone (11-hydroxybadkhyzin (6)), and nordaucane sesquiterpene (norlasidiol angelate (7)) from L. hispidum, whereas L. petrophilum yielded 10β-acetoxy-8α-angeloyloxy-6αH,7αH-guaian-3-en-12,6-olide (8), 10β-acetoxy-8α-senecioyloxy-6αH,7αH-guaian-3-en-6,12-olide (9) and acetylisomontanolide (10). Molecular docking simulations revealed stable interactions between compounds 7 and 9 with estrogen receptor α (ERα) and vascular endothelial growth factor receptor 2 (VEGFR2), with compound 7 showing superior stability and binding affinity. In silico ADME predictions indicated favorable pharmacokinetic properties, including high oral absorption. Compounds 7 and 9, representing new nordaucane and sesquiterpene lactones, have not been previously reported. Invitro cytotoxicity revealed that compound 7 exhibits potent anti-cancer activity against MCF-7 cells, whereas compound 9 showed reduced cytotoxicity. Invivo testing in Caenorhabditis elegans supported these findings, suggesting safety and efficacy in organisms. In silico results emphasize the potential of these compounds, with compound 7 promising due to its stability and strong binding affinity.

A cyclic peptide toolkit reveals mechanistic principles of peptidylarginine deiminase IV regulation.

Peptidylarginine deiminase IV (PADI4, PAD4) deregulation promotes the development of autoimmunity, cancer, atherosclerosis and age-related tissue fibrosis. PADI4 additionally mediates immune responses and cellular reprogramming, although the full extent of its physiological roles is unexplored. Despite detailed molecular knowledge of PADI4 activation in vitro, we lack understanding of its regulation within cells, largely due toa lack of appropriate systems and tools. Here, we develop and apply a set of potent and selective PADI4 modulators. Using the mRNA-display-based RaPID system, we screen >1012 cyclic peptides for high-affinity, conformation-selective binders. We report PADI4_3, a cell-active inhibitor specific for the active conformation of PADI4; PADI4_7, an inert binder, which we functionalise for the isolation and study of cellular PADI4; and PADI4_11, a cell-active PADI4 activator. Structural studies with PADI4_11 reveal an allosteric binding mode that may reflect the mechanism that promotes cellular PADI4 activation. This work contributes to our understanding of PADI4 regulation and provides a toolkit for the study and modulation of PADI4 across (patho)physiological contexts.

STRUCTURALISM OF TODOROV'S SEMIOTICS IN THE MOVIE "HACKSAW RIDGE" DIRECTED BY MEL GIBSON

This research discusses the structuralism of Todorov's semiotics in the movie "Hacksaw Ridge" directed by Mel Gibson. Structuralist studies have been abandoned for a long time. This study aims to determine the implementation of semiotic aspects of Todorov structuralism in films. A descriptive-qualitative method was used to analyze the data, and note-taking with Nvivo 12 software was used as the data collection technique. This study required a long process and knowledge of data analysis, which required importing, transcript, reducing, presenting and drawn conclusion. The findings examined the syntactical aspects of the 38 sequences found, including the form of words, events, characters, and verbal aspects, including mode, kala, point of view, and storytelling. This study concludes that film can be implemented in structured narrative and structuralism studies based on the Todorov model. This research has important implications for providing a deeper understanding of films’ creative excellence, thematic significance, and potential emotional impact.

Localized Thermoresponsive Behavior in P(NIPAm‐co‐AAc) Copolymers: Structural Insights From Rheology and Small Angle X‐Ray Scattering

ABSTRACTStimuli‐responsive polymers stand out for their ability to respond to small environmental changes. One of the most representative thermo‐sensitive materials is poly(N‐isopropyl acrylamide) (PNIPAm), which presents reversible phase transitions close to the human body temperature. However, previous studies observed that the copolymerization of NIPAm with small quantities of different monomers like acrylic acid (AAc) results in copolymers with reduced or lost thermo‐responsivity. In this study, thermo‐sensitive PNIPAm, pH‐sensitive poly(acrylic acid) (PAAc), and various proportions of their copolymers P(NIPAm‐co‐AAc) were obtained by free radical polymerization and thoroughly characterized. Rheological and structural studies reveal the remaining thermosensitivity of the copolymers manifested at short molecular ranges. These alterations in short‐range interactions are observed in all samples containing NIPAm, and they are evidenced by changes in the fractality of their structure and flow index behavior of the Viscosity Ostwald–de Waele Model. Particularly, when the copolymer proportion of NIPAm/AAc is about 40/60, the Beaucage model reveals two structural levels, ~200 and ~10 nm. Furthermore, the model exhibits a thermal response of the lower‐size substructures, indicating possible segregation of NIPAm‐rich regions from copolymer chains. The evidence found in this work could contribute to the development of nanosystems, in which local thermoresponsive effects are sought, such as for active drug targeting.

Hydrothermal Approach of Spinel Copper Cobaltite (CuCo2O4) Nanostructures and Their Structural and Functional Properties

CuCo2O4 nanoparticles were synthesized via facile hydrothermal route using oxalic as a precipitant, thermal decomposition of CuCo2O4 precursor at 400[Formula: see text]C. The structural studies from X-ray diffraction (XRD), Fourier transform infrared spectrometer, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) disclose the predominant spinel crystal phase for copper cobaltite. The optical absorption spectra reveal two band gaps of 3.8[Formula: see text]eV and 4.4[Formula: see text]eV in the CuCo2O4 nanoparticles. The cyclic voltammetry (CV) was used to assess the electrochemical characteristics of the resulting product in an organic electrolyte at −1.5–1.5[Formula: see text]V under ambient conditions. On 22.4[Formula: see text]nm CuCo2O4 nanoparticles, a greater capacitance of 920[Formula: see text]F/g at a scan rate of 5[Formula: see text]mV/s was achieved.