Structural Complex Research Articles

Structure of axial and radial sieve tubes and its functional significance for the phloem network in Aquilaria sinensis (Thymelaeaceae)

Summary The structure of axial and radial or ray sieve tubes was examined by fluorescence microscopy and SEM. Two types of sieve areas were found on the lateral walls of axial and radial sieve tubes: one consists of a cluster of larger, more highly differentiated sieve pores, corresponding to sieve plates, and the other consists of scattered or clustered minute sieve pores, arranged in a linear array in the latter along the cell axis, covered by slime bodies, making a new structure complex associated with nutrient pathways. Migration of cytoplasmic slime bodies in axial and radial sieve tubes was observed to take place by changing shape into filamentous or tubular slimes and passing through the sieve pores, depending on the size of the pores at the xylem differentiation stage. Axial sieve tubes in the interxylary phloem were observed to be arranged axially in dense bundles rather than sparsely scattered. Rarely, it was observed that axial sieve tubes themselves branched off and merged with other axial sieve tubes without being bridged by radial sieve tubes in the ray tissue. Parenchyma cells and ray tissue in the interxylary phloem were unlignified in all the secondary xylem from the 12-year-old tree of Aquilaria sinensis. The division of ray parenchyma cells was often observed in the mature secondary xylem. Furthermore, two types of radial sieve tubes at different stages of differentiation were observed in the same ray tissue, suggesting that at least younger radial sieve tubes differentiate from ray parenchyma cells in the secondary xylem. Based on the positioning of radial sieve tubes and axial sieve tubes in the secondary xylem, three types of connections were identified; (1) radial sieve tube strand in interxylary phloem connects to axial sieve tube strand; (2) radial sieve tube strand bridges two interxylary phloems; (3) radial sieve tube strand anastomoses with interxylary phloem and connects to axial sieve tube strand. The highest frequency of (1) among the three types suggests that it is crucial for the functioning of the phloem network and that radial sieve tubes and axial sieve tubes located inside the interxylary phloem are connected to establish longitudinal transport channels.

Investigating the Effect of Maltodextrins and Degree of Polymerization on Individual Complex Carbohydrate Taste Sensitivity.

Research shows that complex carbohydrates (maltodextrins) can be perceived in the oral cavity independent of sweet taste. However, little is known about individual differences in complex carbohydrate taste sensitivity. Therefore, the relationship between complex carbohydrate structure and individual complex carbohydrate taste sensitivity requires further investigation. This study investigated individual taste sensitivity among adults for maltodextrins with different degrees of polymerization. Participants (n = 37) (BMI (kg/m2): 24.29 ± 1.06, age (years): 30.32 ± 1.24) taste perception and oral sensitivity for sour (citric acid), sweet (glucose), and complex carbohydrate (mixture of short chain maltodextrins (SCM, average DP 6) and mixture of long chain maltodextrin (LCM, average DP 20)) were assessed using taste assessment measures (detection threshold (DT) and suprathreshold intensity perception (ST)). Taste assessment measures were performed in a randomized, repeated, blinded design. There were significant correlations between LCM DT, SCM DT, Sour DT, and Sweet DT (all p < 0.01). There were further significant correlations between LCM ST, SCM ST and Sweet ST (all p < 0.01) and between SCM ST, Sweet ST and Sour ST (all p < 0.01). There was a significant effect of sex on DT ranking values (p = 0.050). For the majority of participants, complex carbohydrate sensitivity status did not change according to chain length. This study strengthens existing research that complex carbohydrates can be perceived in the oral cavity and highlighted that for the majority, maltodextrin chain length does not influence complex carbohydrate taste sensitivity (specifically DT and ST).

Epigene functional diversity: isoform usage, disordered domain content, and variable binding partners

BackgroundEpigenes are defined as proteins that perform post-translational modification of histones or DNA, reading of post-translational modifications, form complexes with epigenetic factors or changing the general structure of chromatin. This specialized group of proteins is responsible for controlling the organization of genomic DNA in a cell-type specific fashion, controlling normal development in a spatial and temporal fashion. Moreover, mutations in epigenes have been implicated as causal in germline pediatric disorders and as driver mutations in cancer. Despite their importance to human disease, to date, there has not been a systematic analysis of the sources of functional diversity for epigenes at large. Epigenes’ unique functions that require the assembly of pools within the nucleus suggest that their structure and amino acid composition would have been enriched for features that enable efficient assembly of chromatin and DNA for transcription, splicing, and post-translational modifications.ResultsIn this study, we assess the functional diversity stemming from gene structure, isoforms, protein domains, and multiprotein complex formation that drive the functions of established epigenes. We found that there are specific structural features that enable epigenes to perform their variable roles depending on the cellular and environmental context. First, epigenes are significantly larger and have more exons compared with non-epigenes which contributes to increased isoform diversity. Second epigenes participate in more multimeric complexes than non-epigenes. Thirdly, given their proposed importance in membraneless organelles, we show epigenes are enriched for substantially larger intrinsically disordered regions (IDRs). Additionally, we assessed the specificity of their expression profiles and showed epigenes are more ubiquitously expressed consistent with their enrichment in pediatric syndromes with intellectual disability, multiorgan dysfunction, and developmental delay. Finally, in the L1000 dataset, we identify drugs that can potentially be used to modulate expression of these genes.ConclusionsHere we identify significant differences in isoform usage, disordered domain content, and variable binding partners between human epigenes and non-epigenes using various functional genomics datasets from Ensembl, ENCODE, GTEx, HPO, LINCS L1000, and BrainSpan. Our results contribute new knowledge to the growing field focused on developing targeted therapies for diseases caused by epigene mutations, such as chromatinopathies and cancers.

The influence of sodium alginate on kaolinite flocculation in presence of metal ions: guidance for green processing

In this study, the responsiveness of Na+, Mg2+, Ca2+ and Al3+ to sodium alginate (SA) and their influence on kaolinite dispersion/flocculation behavior were investigated through rheology and turbidity tests. The effects of metal ions on the interaction between SA and kaolinite were analyzed by zeta potential, fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). The results showed that Na+ and Mg2+ resulted in a decreasing of the viscosity and modulus of SA solution for they have the electrostatic shielding effect on SA. Ca2+ and Al3+ significantly increased the viscosity and modulus of SA solution because Ca2+ and Al3+ not only have the electrostatic shielding effect on SA but also could form the different network structure complexes. The order of the responsiveness of metal ions and SA sorted by intensity level was: Al3+> Ca2+>Mg2+> Na+. SA has a dispersion effect on kaolinite particles under the background of Na+ and Mg2+, and SA has a flocculation effect on kaolinite particles in the presence of Ca2+ and Al3+. The flocculation efficiency of SA on kaolinite suspension containing Al3+ was much higher than that of SA on kaolinite suspension in the presence of Ca2+. Zeta potential and FTIR results showed that SA could be adsorbed on the kaolinite surface through electrostatic force and hydrogen bond in the presence of Na+ and Mg2+. Microscope observation, XPS and DFT results showed SA could not only form chemical adsorption with Ca2+/Al3+ on the kaolinite surface but also be cross-linked with Ca2+/Al3+ to form a network structure, which could sweep and trap kaolinite particles in suspension. This work has strategic significance for the responsiveness of natural polysaccharide to metal ions and their application in environmental protection of mine wastewater, as well as the clean and circular utilization of water.

New Technologies of Grain Boundary Engineering of Materials for Improving the Corrosion Resistance of High Alloy Stainless Steel Pipes

Abstract. Problem. Pipes made of highly alloyed corrosion-resistant steels are widely used in corrosive-aggressive environments in priority industries. In connection with the increasing severity of their operating conditions, increased requirements for resistance to intercrystalline, pitting corrosion, corrosion cracking, and sulfide corrosion cracking under stress become the most important in accordance with the requirements of foreign and international standards. Previous studies have shown that currently operating technologies for the production of pipes do not meet the modern, comprehensive requirements for quality characteristics. To solve this problem, it is necessary to apply new progressive scientific and technological methods. Goal. The purpose of the work is to increase the corrosion resistance and operational reliability of pipes made of highly alloyed austenitic and ferritic-austenitic steels by improving their structure during deformation and temperature treatments according to the principle of grain boundary engineering of materials. Methodology. To achieve the goal, the latest scientific achievements and technologies for improving the structure and increasing the corrosion resistance of rolled products made of high-alloy steel were analyzed. When conducting experimental studies, modern methods were used and methods of metal structure research and complex corrosion tests for resistance to local types of corrosion to which corrosionresistant steels are subjected in operating conditions were developed. The results. The latest technologies for the production of pipes from austenitic chromenickel and ferritic-austenitic chrome-nickelmolybdenum steels, based on the principle of grain boundary construction of polycrystalline materials, have been developed. They ensure obtaining a structure of pipes with an increased content of special low-energy grain boundaries in the theory of coinciding site lattices (CSL) and high resistance against local types of corrosion in accordance with new industry requirements. Originality. For the first time, special low-energy grain boundaries in the ferritic component and interphase boundaries with reduced surface energy in highly alloyed ferriticaustenitic steels were found. The leading role of special boundaries in increasing resistance to local types of corrosion that originate at grain boundaries is shown. Practical value. The results of the work were implemented in the production at Centravis Production Ukraine PJSC, which contributed to the improvement of the quality and competitiveness of products

X2-GNN: A Physical Message Passing Neural Network with Natural Generalization Ability to Large and Complex Molecules.

Neural network models excel in molecular property predictions but often struggle with generalizing from smaller to larger molecules due to increased structural diversity and complex interactions. To address this, we introduce an E(3) invariant (and equivariant capable) message passing graph neural network (GNN), namely, X2-GNN, that integrates physical insights via atomic orbital overlap integrals and core Hamiltonians. These features provide essential information about bond strength, electron delocalization, and many-body interactions, enhanced by an attention mechanism for improved learning efficiency. Benchmarked against mainstream GNNs on diverse data sets, X2-GNN trained solely on the QM9 data set (up to nine heavy atoms) effectively generalizes to larger molecules with tens of heavy atoms, achieving credible per-atom error rates. It also excels in potential energy surface modeling and accurately predicts the bond dissociation energy within subseconds. These results highlight X2-GNN's scalability and broad applicability, emphasizing the importance of integrating data-driven approaches with basic knowledge from electronic structure theory.

Geology and sandbox analogue modelling of the Karatau structural complex (Southern Urals)

The Urals is an example of a Paleozoic orogen which extends for nearly 2,500 km and represents the geographic border between Europe and Asia. From north to south, it is divided into Polar, Cis-Polar, Northern, Middle and Southern Urals. One of the most geologically complicated structures of the Southern Urals is the Karatau structural complex (KSC). Its complexity is confirmed by the diversity of points of view on the origin: 1) the complex arose due to vertical movements; 2) the complex is thrusted as a result of horizontal compression; 3) the complex is a flexural bulge resulted of a load on the lithosphere. The KSC belongs to the Bashkirian Megazone, part of the shortened paleomargin mainly composed of Riphean-Vendian deposits (1650–540 Ma) above an Archean basement. It appears on the map as a nearly square-shaped structure bounded by two strike-slip faults where the western deformation front of the Ural is apparently offset by 20 to 30 km to the northwest. We follow Kamaletdinov’s and Brown’s ideas, where a shortening is applied parallel to a former elongated extensional sedimentary basin perpendicular to the margin. The result being a farther propagation of the deformation front within the deep basin bounded by normal faults, which are reactivated as transfer strike-slip faults. The geodynamic setting thus corresponds to a rift-rift-rift triple junction reactivated during the orogenic shortening. We reviewed and compared the most recently available geological data and seismic lines. Subsequently, we constructed a series of new geological sections to refine the depth of the former rift sequences and the décollements both within and outside the KSC. Using this precise model of décollement depth, we use sandbox analogue modelling to better understand the kinematic and mechanic evolution of the KSC and test our hypothesis. Sandbox analogue modelling made it possible to recreate the general features of the KSC: approximative number of thrusts, their forward propagation to the west with respect to the front of deformation outside the KSC, and the differential shortenings with models respecting the constraints on the variations of décollements depths within and outside the KSC.

Clinical features and genetic analysis of 471 cases of fetal congenital heart disease

BackgroundCongenital heart disease (CHD) is a heterogeneous collection of structural abnormalities of the heart or great vessels that are present at birth. These birth defects are one of the leading causes of infant mortality and morbidity worldwide. The etiology and pathogenesis of CHD are unclear and largely considered to be multifactorial in nature. Since the chromosomal profile of CHD has not been analyzed in a large sample size, we aimed to summarize the clinical features, cytogenetics findings, and pregnancy outcomes of CHD to provide a clinical reference for prenatal diagnosis.MethodsAmong 21,152 pregnant women, 471 (2.23%) showed fetal CHD on cordocentesis or amniocentesis. The number of cases showing simple CHD, simple CHD with concomitant extracardiac structural abnormalities, complex CHD, and complex CHD with concomitant extracardiac structural abnormalities was 128, 124, 89, and 130, respectively. For prenatal genetic diagnosis, karyotyping was performed with single-nucleotide polymorphism array(SNP-array)-based chromosomal microarrays, fluorescence in situ hybridization (FISH), copy number variation sequencing (CNV-seq), and BACs-on-Beads™ (BoBs) analyses. The results of ultrasonography examinations, genetic analyses, and pregnancy outcomes were recorded in detail.ResultsVentricular septal defects (VSDs) were observed in 245 (52.02%) cases of fetal CHD. Among the 471 cases of CHD, 258 (54.78%) showed other ultrasound abnormalities. The most common ultrasound abnormalities were abnormalities of the central nervous system. The 471 cases included 93 (19.75%) cases showing chromosomal abnormalities, and the incidence of these abnormalities increased with advanced maternal age or the presence of other ultrasound abnormalities. In eight cases, karyotype analysis showed normal results while SNP-array or CNV-seq results were abnormal. Among the 453 cases that were followed up, 166 (36.64%) involved pregnancy termination, 273 (60.26%) involved live births, 7 (1.55%) involved fetal death in utero, and 7 (1.55%) involved neonatal death after birth.ConclusionsFetuses with CHD showed higher rates of chromosomal abnormalities. In cases diagnosed with fetal CHD during fetal ultrasonic examination, the mothers should undergo a careful and comprehensive fetal ultrasound scan as well as prenatal genetic testing, including karyotype analysis and SNP-array or CNV-sequencing. The prognosis for simple fetal CHD is good, while the prognosis for complex fetal CHD and extracardiac anomalies is poor.

Evaluating coral reef restoration in marine protected areas using habitat structural complexity and coral communities.

Marine Protected Areas (MPAs) are widely used to protect at-risk ecosystems. This study employed a combined method to quantify the protection performance on coral reef habitats, integrating coral morphology and topographic relief in the rugosity index. In the Weizhou Island reef in the northern South China Sea, after six years of protection, the no-take areas (NTAs) hosted a greater live coral cover (11.7%) compared to the no-protection areas (NPAs, 6.9%), but had a lower rugosity (1.17) than both the NPAs and the habitat protection areas, suggesting that while MPAs enhance coral cover, their benefits for habitat structural complexity may remain insignificant in the short term (six years). In the NTAs, the contribution of live corals to habitat complexity (28.3%) was lower than that of rubbles (34.4%). Moreover, slow-growing massive corals (e.g., Porites lutea), which usually have low rugosity, contributed a larger portion (up to 20%) to habitat complexity. In contrast, fast-growing, structural complex arborescent corals (e.g., Acropora pruinosa) had a limited contribution (2.3%). Foliose corals, which dominated the coral community also have lower rugosity (1.2 ~ 1.3) compared to massive and arborescent corals, presumably due to phenotypic plasticity in response to specific environmental conditions. This study suggests that prioritizing coral species composition, especially corals with high rugosity, is important for effective reef framework reconstruction.

Tailored Carbon Dots in Solar Energy Conversion Schemes

Addressing the dual challenge of meeting the world's escalating energy needs while simultaneously decreasing carbon dioxide emissions has emerged as a pivotal issue in the new millennium. The Statistical Review of World Energy's latest report by British Petroleum Company plc reveals that global power consumption was around 18.9 terawatts (TW) in 2021, with projections estimating a surge to 30 TW by 2050. In stark contrast, solar radiation delivers a 120,000 TW to the Earth's surface, a quantity that exceeds the projected energy consumption of 2050 by 4,000 times. Efficiently harnessing and storing this immense solar energy is increasingly seen as a viable route towards a sustainable energy network. A promising solution lies in carbon-based systems. Carbon dots (CDs), an emerging class of nanomaterials, show great potential in this field. These can be synthesized through scalable methods using various carbon and nitrogen precursors, including waste, making them both cost-effective and recyclable. CDs offer a range of photophysical properties, such as variable photoluminescence and the generation of spin-active states. Furthermore, CDs are biocompatible, non-toxic, and environmentally friendly. Unlike traditional binary semiconductors, their photocatalytic attributes can be finely adjusted using a variety of organic chemistry functionalization techniques. While CDs have primarily been optimized for PL properties, their application in metal-free photocatalysis remains largely untapped. Major obstacles are the large structural diversity and complex multicomponent arrangement of CDs, along with the high variability of their photoactive centers, presenting a unique challenge. The ongoing controversy over the exact CDs structure, further compounded by a limited understanding of how this structure influences their photophysical properties, significantly hinders advancements in CDs design. This challenge significantly hampers progress in the development of more effective CDs for solar-driven water-splitting, underscoring the urgent need for increased collaboration between experimentalists and theoreticians now more than ever. In this contribution, we delve into the current understanding of photocatalytically active CD-based systems. The focus is set on model systems that feature no co-catalysts. We explore the role of CDs, shed light on the structure-activity relationship and detail photon- and charge-management in the excited state. Additionally, we share our insights on the potential opportunities that emerge from a deeper comprehension of CDs.

Ixochymostatin, a trypsin inhibitor-like (TIL) protein from Ixodes scapularis, inhibits chymase and impairs vascular permeability

Ticks obtain a blood meal by lacerating small blood vessels and ingesting the blood that flows to the feeding site, which triggers various host responses. However, ticks face the challenge of wound healing, a process involving hemostasis, inflammation, cell proliferation and migration, and remodeling, hindering blood acquisition. To overcome these obstacles, tick salivary glands produce an array of bioactive molecules. Here, we characterize ixochymostatin, an Ixodes scapularis protein belonging to the trypsin inhibitor-like (TIL) family. It is expressed in multiple developmental stages and in tick salivary glands and acts as a slow and tight-binding inhibitor of chymase, cathepsin G, and chymotrypsin. Predictions for the tertiary structure complex between ixochymostatin and chymase suggest a direct interaction between the inhibitor reactive site loop and protease active sites. In vitro, ixochymostatin protects the endothelial cell barrier against chymase degrading action, decreasing cell permeability. In vivo, it reduces vascular permeability induced by chymase and compound 48/80, a mast cell degranulator agonist, in a mouse model. Additionally, ixochymostatin inhibits the chymase-dependent generation of vasoconstrictor peptides. Antibodies against ixochymostatin neutralize its inhibitory properties, with epitope mapping identifying potential neutralization regions. Ixochymostatin emerges as a novel tick protein modulating host responses against tick feeding, facilitating blood acquisition.

Genomic rare variant mechanisms for congenital cardiac laterality defect: A digenic model approach.

Laterality defects are defined by perturbations in the usual left-right asymmetry of organs. Due to low known genetic etiology of congenital heart disease (CHD) cases (less than 40%), we used a digenic model approach for the identification of contributing variants in known laterality defect genes (N = 115) in the exome/genome sequencing (ES/GS) data from individuals with clinically diagnosed laterality defects. The unsolved ES/GS data were analyzed from three CHD cohorts: Baylor College of Medicine-Genomics Research to Elucidate the Genetics of Rare Diseases (BCM-GREGoR; N = 247 proband ES), Gabriella Miller Kids First Pediatric Research program (Kids First; N = 158 trio GS), and Pediatric Cardiac Genomics Consortium (PCGC; N = 163 trio ES), and trans-heterozygous digenic variants were identified in 2.8% (inherited digenic variants in 0.4%), 8.2%, and 13.5% cases respectively, which was significantly higher as compared to 602 control trios provided by the 1000 Genomes Project (p = 0.001, 1.4e-07, and 8.9e-13, respectively). Trans-heterozygous digenic variants were also identified in 0.4%, and 1.4% cases with non-laterality CHD in Kids First and PCGC datasets, respectively, which was not statistically significant as compared to control trios ( p = 1, and 0.059, respectively). Altogether, in laterality cohorts, 23% of digenic pairs were in the same structural complex of motile cilia. Out of 39 unique digenic pairs in laterality CHD, 29 are more likely to be potential digenic hits as predicted by DiGePred tool. These findings provide further evidence that digenic epistatic interaction can contribute to the complex genetics of laterality defects.

Biorefinery and Bioremediation Strategies for Efficient Management of Recalcitrant Pollutants Using Termites as an Obscure yet Promising Source of Bacterial Gut Symbionts: A Review.

Lignocellulosic biomass (LCB) in the form of agricultural, forestry, and agro-industrial wastes is globally generated in large volumes every year. The chemical components of LCB render them a substrate valuable for biofuel production. It is hard to dissolve LCB resources for biofuel production because the lignin, cellulose, and hemicellulose parts stick together rigidly. This makes the structure complex, hierarchical, and resistant. Owing to these restrictions, the junk production of LCB waste has recently become a significant worldwide environmental problem resulting from inefficient disposal techniques and increased persistence. In addition, burning LCB waste, such as paddy straws, is a widespread practice that causes considerable air pollution and endangers the environment and human existence. Besides environmental pollution from LCB waste, increasing industrialization has resulted in the production of billions of tons of dyeing wastewater from several industries, including textiles, pharmaceuticals, tanneries, and food processing units. The massive use of synthetic dyes in various industries can be detrimental to the environment due to the recalcitrant aromatic structure of synthetic dyes, similar to the polymeric phenol lignin in LCB structure, and their persistent color. Synthetic dyes have been described as possessing carcinogenic and toxic properties that could be harmful to public health. Environmental pollution emanating from LCB wastes and dyeing wastewater is of great concern and should be carefully handled to mitigate its catastrophic effects. An effective strategy to curtail these problems is to learn from analogous systems in nature, such as termites, where woody lignocellulose is digested by wood-feeding termites and humus-recalcitrant aromatic compounds are decomposed by soil-feeding termites. The termite gut system acts as a unique bioresource consisting of distinct bacterial species valued for the processing of lignocellulosic materials and the degradation of synthetic dyes, which can be integrated into modern biorefineries for processing LCB waste and bioremediation applications for the treatment of dyeing wastewaters to help resolve environmental issues arising from LCB waste and dyeing wastewaters. This review paper provides a new strategy for efficient management of recalcitrant pollutants by exploring the potential application of termite gut bacteria in biorefinery and bioremediation processing.

Leveraging Ligand Desymmetrization to Enrich Structural Diversity of Zirconium Metal-Organic Frameworks for Toxic Chemical Adsorption.

The discovery of metal-organic frameworks (MOFs) with novel structures provides significant opportunities for developing porous solids with new properties and enriching the structural diversity of functional materials for various applications. The rational design of building units with specific geometric conformations is essential to direct the construction of MOFs with unique properties. Herein, we leverage a ligand desymmetrization approach to construct a series of new MOFs. A flexible tetratopic carboxylate ligand with a tetrahedral geometry was designed and assembled with a Zr6 cluster, generating four Zr-based MOF structures: NU-2600, NU-2700, NU-2800, and NU-1802, in which the ligand configurations and Zr6 cluster connectivities can be controlled by varying solvents and modulators during synthesis. Except for NU-1802, these represent entirely new topologies. Notably, NU-1802 exhibits structural flexibility, with up to a 74 % reduction in the unit cell volume as confirmed by single-crystal X-ray diffraction studies. Given their microporous structures, we studied the adsorption behaviors of n-hexane and 2-chloroethyl ethyl sulfide to explore the structure-property relationships of these MOFs. Overall, this work highlights ligand desymmetrization as a powerful method to enrich MOF structural diversity and access complex MOFs with non-default topologies suitable for applications such as toxic gas capture.

Leveraging Ligand Desymmetrization to Enrich Structural Diversity of Zirconium Metal–Organic Frameworks for Toxic Chemical Adsorption

The discovery of metal–organic frameworks (MOFs) with novel structures provides significant opportunities for developing porous solids with new properties and enriching the structural diversity of functional materials for various applications. The rational design of building units with specific geometric conformations is essential to direct the construction of MOFs with unique properties. Herein, we leverage a ligand desymmetrization approach to construct a series of new MOFs. A flexible tetratopic carboxylate ligand with a tetrahedral geometry was designed and assembled with a Zr6 cluster, generating four Zr‐based MOF structures: NU‐2600, NU‐2700, NU‐2800, and NU‐1802, in which the ligand configurations and Zr6 cluster connectivities can be controlled by varying solvents and modulators during synthesis. Except for NU‐1802, these represent entirely new topologies. Notably, NU‐1802 exhibits structural flexibility, with up to a 74% reduction in the unit cell volume as confirmed by single‐crystal X‐ray diffraction studies. Given their microporous structures, we studied the adsorption behaviors of n‐hexane and 2‐chloroethyl ethyl sulfide to explore the structure‐property relationships of these MOFs. Overall, this work highlights ligand desymmetrization as a powerful method to enrich MOF structural diversity and access complex MOFs with non‐default topologies suitable for applications such as toxic gas capture.

Controllable Synthesis of Oxa‐/Thia‐Spirohydroquinolines by [3+(2+1)] Annulation of Aromatic Amines with Bimolecular O/S‐Heterocyclic Ketones

Abstract[3+(2+1)] Annulation represents the most straightforward and atom‐economical strategies in organic synthesis for the efficient construction of diverse cyclic structural units and complex molecules. Herein, we present a Lewis acid Sc(OTf)3‐catalyzed controlled synthesis of two different regioselective oxa/thia‐spirohydroquinolines (C=C at the α/β‐site of O/S‐atom) from aromatic amines and bimolecular O/S‐heterocyclic ketones via intermolecular [3+(2+1)] annulation. This method features mild reaction conditions, high step economy and atom utilization, and the O/S‐heterocyclic ketone can act as both two‐ and one‐carbon synthons. Furthermore, density functional theory (DFT) calculations indicate that the intrinsic cause of this unique regioselectivity is caused by the proton abstraction step.

Semisynthetic Phage Display Library Construction: Design and Synthesis of Diversified Single-Chain Variable Fragments and Generation of Primary Libraries.

Display of antibody fragments on the surface of M13 filamentous bacteriophages is a well-established approach for the identification of antibodies binding to a target of interest. Here, we describe the first of a three-step method to construct Antibody Libraries for Therapeutic Antibody Discovery (ALTHEA) Libraries. The three-step method involves (1) primary library (PL) construction, (2) filtered library construction, and (3) secondary library construction. The first step, described here, entails design, synthesis, and cloning of four PLs. These PLs are designed with specific properties amenable to therapeutic antibody development using one universal variable heavy (VH) scaffold and four distinct variable light (VL) scaffolds. The scaffolds are diversified in positions that bind both protein and peptide targets identified in antibody-antigen complexes of known structure using the amino acid frequencies found in those positions in known human antibody sequences, avoiding residues that may lead to developability liabilities. The diversified scaffolds are combined with 90 synthetic neutral HCDR3 sequences designed with developable human diversity genes (IGHD) and joining heavy genes (IGHJ) in germline configuration, and assembled as single-chain variable fragments (scFvs) in a VL-linker-VH orientation. The four designed PLs are synthesized using trinucleotide phosphoramidites (TRIMs) and cloned independently into a phagemid vector for M13 pIII display. Quality control of the cloning of the four PLs is also described, which involves sequencing scFvs in each library.

Analysis of the Sr2GdTi2Nb3O15 ceramic: Investigation into its structural properties and complex impedance spectroscopy

In this study, we successfully synthesized tetragonal tungsten bronze with the nominal formula Sr2GdTi2Nb3O15 and systematically examined of its structure, dielectric, and electrical properties. The material was synthesized through the solid-state reaction technique at a temperature of 1350 °C. The formation of the tetragonal tungsten bronze in the P4/mbm space group was verified via Rietveld refinement using X-ray diffraction data. The electrical characteristics of the ceramic were examined using non-destructive complex impedance spectroscopy (CIS) across a range of frequencies (10–106 Hz) at various temperatures. The real component of impedance (Z') displayed a decrease with rising frequency, suggesting a negative temperature coefficient of resistance (NTCR) for this sample. The Cole-Cole plot of the compound exhibits two semicircles, with the compound's resistance gradually decreasing as the temperature increased. Moreover, the activation energy (Ea) was found to be approximately 0.9 eV, which confirms that oxygen vacancies are responsible for the observed relaxation behavior. Complex modulus analysis confirmed the presence of non-Debye relaxations. These results contribute to a thorough comprehension of the structural and electrical characteristics of Sr2GdTi2Nb3O15, opening avenues for potential applications in diverse electronic devices.

Cnn-assisted multi-hop graph attention network for hyperspectral image classification

ABSTRACT Recently, the convolutional neural network (CNN) has gained widespread adoption in the hyperspectral image (HSI) classification owing to its remarkable feature extraction capability. However, the fixed acceptance domain of CNN restricts it to Euclidean image data only, making it difficult to capture complex information in hyperspectral data. To overcome this problem, much attention has been paid to the graph attention network (GAT), which can effectively model graph structure and capture complex dependencies between nodes. However, GAT usually acts on superpixel nodes, which may lead to the loss of pixel-level information. To better integrate the advantages of both, we propose a CNN-assisted multi-hop graph attention network (CMGAT) for HSI classification. Specifically, a parallel dual-branch architecture is first constructed to simultaneously capture spectral-spatial features from hyperspectral data at the superpixel and pixel levels using GAT and CNN, respectively. On this basis, the multi-hop and multi-scale mechanisms are further employed to construct a multi-hop GAT module and a multi-scale CNN module to capture diverse feature information. Secondly, an attention module is cascaded before the multi-scale CNN module to improve classification performance. Eventually, the output information from the two branches is weighted and fused to produce the classification result. We performed experiments on four benchmark HSI datasets, including Indian Pines (IP), University of Pavia (UP), Salinas Valley (SV) and WHU-Hi-LongKou (LK). The results demonstrate that the proposed method outperforms several deep learning methods, achieving overall accuracies of 95.67%, 99.04%, 99.55% and 99.51%, respectively, even with fewer training samples.

HUMIC ACIDS: PROPERTIES, STRUCTURE, AND APPLICATION

Humic substances (HSs) are a diverse class of natural compounds with no fixed chemical composition, formed from plant and microbial residues through the action of environmental factors and living organisms over many years. Despite extensive research spanning two centuries, the complex and variable nature of HSs' structure remains a subject of scientific inquiry. These substances, notably humic acids, fulvic acids, and humin, play crucial roles in ecological and environmental processes due to their abundant functional groups and resilience to biodegradation. This review explores the intricate structure and properties of HSs, their classification, and their occurrence in nature. It highlights the different models proposed to describe the structural fragments of humic acids, emphasizing their aromatic cores and diverse functional groups. The variability in the molecular weight distribution of HSs, attributed to their polydisperse nature, is also discussed, along with methods used for their determination, such as exclusion chromatography. Furthermore, the elemental and functional compositions of humic acids are examined, detailing their acid-base properties and capacity for heavy metal complexation. The synthesis of HSs from natural sources, such as soil, peat, coal, and artificial processes, is covered, showcasing methods like alkaline extraction and hydrothermal treatment. Recent advancements in artificial humification, including oxidative ammonolysis and Fenton reagent-based oxidation, are reviewed for their potential in producing environmentally friendly humic materials from lignin and waste biomass. The study concludes by underscoring the environmental significance and practical applications of HSs, particularly in agriculture, soil conditioning, and environmental remediation. The diverse properties and synthesis methods of HSs make them promising candidates for sustainable material production and environmental management. Humic acids are versatile compounds beneficial for human health due to their potent antioxidant properties, immune-modulating effects, and support for gastrointestinal health and detoxification. Structurally diverse, they feature groups like carboxyl, phenolic hydroxyl, quinones, ketonic carbonyls, amino, and sulfhydryl, contributing to their stability and amphiphilic nature. In pharmaceutical applications, they show promise for drug delivery, antioxidant therapies, wound healing, antimicrobial actions, and biofilm disruption, underlining their biocompatibility and safety. Key words: