Structural Diversity Research Articles

Natural Kaurane‐class of Diterpenoid Alkaloids: Structure, Distribution, and Bioactivities

Kaurane‐class diterpenoid alkaloids (DAs), an important group of C20‐DAs, include mainly veatchine‐, napelline‐, anopterine‐ and tricalysiamide‐type DAs and several types of DAs with novel skeletons discovered in recent years. To date, approximately 81 compounds belonging to this class of DAs have been isolated from plants in 5 families and 7 genera. Among them, Aconitum is the most important source of this class of DAs. Kaurane‐class DAs exhibit noteworthy biological activities, including antitumor, antiarrhythmic, anti‐inflammatory, and analgesic effects. In particular, anopterine‐type DAs have shown significant antitumor activity in vitro, and napelline‐type DAs have powerful antiarrhythmic effects and great potential in the development of such drugs. In general, the diverse structures and biological activities of kaurane‐class DAs highlight the great potential of these types of compounds for drug discovery, especially antitumor and antiarrhythmic drugs, and is a topic worthy of further in‐depth study.

Nonclassical Optical Response of Particle Plasmons With Quantum‐Informed Local Optics

AbstractAs the dimensions of plasmonic structures or the field confinement length approach the mean free path of electrons, mesoscopic optical response effects, including nonlocality, electron spill‐in or spill‐out, and Landau damping, are expected to become observable. In this work, a quantum‐informed local analogue model (QILAM) that maps these nonclassical optical responses onto a local dielectric film is presented. The primary advantage of this model lies in its compatibility with the highly efficient boundary element method (BEM), which includes retardation effects with relatively large particle sizes. Furthermore, the approach offers a unified framework that connects two important semiclassical theories: the generalized nonlocal optical response (GNOR) theory and the Feibelman d‐parameters formalism. It is envisioned that QILAM can evolve into a multiscale electrodynamic tool for exploring nonclassical optical responses in diverse plasmonic structures in the future. This can be achieved by directly translating mesoscopic effects into observable phenomena, such as plasmon resonance energy shifts and linewidth broadening in the scattering spectrum.

Addressing the Uncertainties in the Environmental Analysis, Modeling, Source and Risk Assessment of Emerging Contaminants

Emerging contaminants (ECs) have become a growing source of worry for environmental researchers and stakeholders in recent decades. Compared with conventional pollutants, ECs can pose environmental risks even at a trace level. The analysis of ECs is typically significantly more challenging than that of conventional pollutants because of their trace amounts and diverse chemical structures. For sound environmental management, it is necessary to perform a comprehensive study of these pollutants. Global concern has increasingly grown over the occurrence, fate, environmental modeling, and risk assessment of such contaminants. Due to the dearth of knowledge in this area, various unc3ertainties inevitably exist in the investigation of ECs. Environmental problems cannot be precisely understood due to the ubiquitous uncertainties in environmental research. Uncertainties and their sources have been reviewed in this study, including spatial and temporal variability, uncertainty in sample collection and analysis, uncertainty in environmental modeling, uncertainty in risk assessment, and uncertainty in source characterization. Some suggestions to reduce uncertainties are summarized. An awareness of uncertainty is necessary for us to have a more accurate understanding and contribute to sound environmental decision-making and management. In addition, more work remains to be performed to reveal the uncertainties in the analysis and risk assessment of ECs.

DIVERSITY OF SECONDARY COMPONENTS OF MULTI- WORD ANATOMICAL TERMS IN POCKET ATLAS OF HUMAN ANATOMY

Medical terms in the atlas can be basically divided into one-word and multi-word terms. Compound words are individual words made from two or more words working together. The object of the article is the relations between Latin and Lithuanian compound anatomical terms, according to diversity of secondary components.The purpose of the article is to reveal the similarities and differences between multi-word Latin and Lithuanian anatomical terms by structural diversity of components. To achieve the purpose, the following research tasks are set: to review the evolution of anatomical nomenclature; to compare Latin and Lithuanian multi-word anatomical terms according to the diversification of structure of components. Research methods. The method of theoretical analysis examines scientific literature, the comparative analysis of terms enables systematisation and generalisation of Latin and Lithuanian anatomical terms in the resource.

Recent Total Syntheses of Cephalotaxine‐Type Alkaloids and Their Structural Diversification (2021–2024): An Update

AbstractCephalotaxine‐type alkaloids present a challenging yet rewarding target for synthetic chemists due to their intricate polycyclic structures and significant biological activity. This review consolidates recent reports (2021–2024) on the total synthesis of cephalotaxine‐type alkaloids, emphasizing innovative catalytic approaches and key transformations that enable efficient construction of the core tetracyclic framework. Advances in techniques such as asymmetric polycyclization, dual catalysis, and rearrangement strategies have streamlined synthetic routes, reducing the number of steps and enhancing stereocontrol. Additionally, structural diversification on the cephalotaxine scaffold during this period has offered valuable insights into structural modifications in medicinal chemistry and potential biosynthetic pathways. This review proposes a new structural classification of cephalotaxine‐type alkaloids. It covers ten recent total syntheses, providing detailed descriptions of the synthetic methodologies employed and comparative analyses with previous syntheses. Four reports on the structural diversification of cephalotaxines are also included.

Resolving and routing magnetic polymorphs in a 2D layered antiferromagnet.

Polymorphism, commonly denoting diverse molecular or crystal structures, is crucial in the natural sciences. In van der Waals antiferromagnets, a new type of magnetic polymorphism arises, presenting multiple layer-selective magnetic structures with identical total magnetization. However, resolving and manipulating such magnetic polymorphs remain challenging. Here, phase-resolved magnetic second harmonic generation microscopy is used to elucidate magnetic polymorphism in 2D layered antiferromagnet CrSBr, demonstrating deterministic and layer-selective switching of magnetic polymorphs. Using a nonlinear magneto-optical technique, we unambiguously resolve the polymorphic spin-flip transitions in CrSBr bilayers and tetralayers through both the amplitude and phase of light. Remarkably, the deterministic routing of polymorphic spin-flip transitions originates from a 'layer-sharing' effect, where the transitions are governed by laterally extended layers acting as 'control bits'. We envision that such controllable magnetic polymorphism could be ubiquitous for van der Waals layered antiferromagnets, enabling new designs and constructions of spintronic and opto-spintronic devices for probabilistic computation and neuromorphic engineering.

The band structure and carrier recombination mechanism of α/β-phase tellurium homojunction investigated by infrared photoluminescence

During the synthesis of tellurium (Te) crystals, the coexistence of multiple crystalline phases (α-Te, β-Te, and γ-Te) with diverse structures commonly occurs, leading to instability and complexity in the performance of Te-based optoelectronic devices. This study employs physical vapor deposition to synthesize Te crystals of various sizes and morphologies, followed by spatially and temperature-dependent evaluation using Raman mapping and infrared photoluminescence (PL) spectroscopy. Spatially resolved results reveal that the size and morphology of Te crystals significantly influence the energy and peak profiles of Raman and PL spectra. Statistical analysis of spatially random sampling indicates the PL peak energies of Te crystals follow a lognormal distribution in terms of their occurrence frequencies, reflecting the complex interplay of multiple factors during crystal growth. This results in the coexistence of α-Te and β-Te phases, forming α/β-Te heterophase homojunction (HPHJ). Meanwhile, temperature-dependent PL results, obtained for the range of 3–290 K, reveal multi-peak competitive behavior in the PL spectra, accompanied by S-shaped shifts in peak energy. These features can be rationally explained by an interface transition-recombination mechanism based on the I-type α/β-Te HPHJ model. It also confirms infrared PL spectroscopy is an effective method for identifying the crystalline phase composition of Te crystals.

Investigating LiDAR Metrics for Old-Growth Beech- and Spruce-Dominated Forest Identification in Central Europe

Old-growth forests are essential for maintaining biodiversity, as they are formed by the complexity of diverse forest structures, such as broad variations in tree height and diameter (DBH) and conditions of living and dead trees, leading to various ecological niches. However, many efforts of old-growth forest mapping from LiDAR have targeted only one specific forest structure (e.g., stand height, basal area, or stand density) by deriving information through a large number of LiDAR metrics. This study introduces a novel approach for identifying old-growth forests by optimizing a set of selected LiDAR standards and structural metrics. These metrics effectively capture the arrangement of multiple forest structures, such as canopy heterogeneity, multilayer canopy profile, and canopy openness. To determine the important LiDAR standard and structural metrics in identifying old-growth forests, multicollinearity analysis using the variance inflation factor (VIF) approach was applied to identify and remove metrics with high collinearity, followed by the random forest algorithm to rank which LiDAR standard and structural metrics are important in old-growth forest classification. The results demonstrate that the LiDAR structural metrics (i.e., advanced LiDAR metrics related to multiple canopy structures) are more important and effective in distinguishing old- and second-growth forests than LiDAR standard metrics (i.e., height- and density-based LiDAR metrics) using the European definition of a 150-year stand age threshold for old-growth forests. These structural metrics were then used as predictors for the final classification of old-growth forests, yielding an overall accuracy of 78%, with a true skill statistic (TSS) of 0.58 for the test dataset. This study demonstrates that using a few structural LiDAR metrics provides more information than a high number of standard LiDAR metrics, particularly for identifying old-growth forests in mixed temperate forests. The findings can aid forest and national park managers in developing a practical and efficient old-growth forest identification and monitoring method using LiDAR.

Efficient Extraction of Phenols from Coal Tar and Preparation of Phenolic Resin-Based Porous Carbon for Advanced Supercapacitor Application.

Developing simple and efficient extraction methods for phenolic substances from coal tar, which facilitate their direct transformation into high-performance electrode materials, holds considerable practical significance. In this study, amide-zinc chloride deep eutectic solvents are employed for efficient phenol extraction. The optimal phenol extraction process is subsequently investigated, and it is found that the robust hydrogen bonding interactions between solvents and phenols significantly enhance extraction efficiency. Notably, without the need for back-extraction, formaldehyde and tetraethyl orthosilicate are added to obtain phenolic resin, which can subsequently be directly carbonized to fabricate hydrangea-like porous carbon. The carbonization mechanism of the phenolic resin is studied, and the templating and activating roles of tetraethyl orthosilicate and zinc chloride assist in the formation of this unique structure. Furthermore, the flexible supercapacitor assembled using the prepared porous carbon and gel electrolyte achieves a high energy density of 31.0Wh kg-1 and demonstrates broad temperature applicability ranging from -25 to 100°C. This work directly converts the extracted phenolic compounds into phenolic resin and shows potential for fabricating porous carbon materials with diverse structures and enhanced capacitive performance.

Synthesis of anisotropic silica nanoparticles by organic amine with diverse structures

Herein, we synthesized anisotropic silica nanoparticles (AISNPs) with organic amines with different structures. Monoamines and diamines with distance between amine groups shorter thanca.4 Å have been observed to facilitate the formation of isotropic silica nanoparticles (ISNPs). AISNPs were synthesized with diamines with distance between amine groups longer thanca.4 Å and linear structures of triamines. Non-linear structures with amine groups positioned in a triangular configuration and the cage-like structure of tetra-amines directed the formation of ISNPs. It has been speculated that the formation of AISNPs would be due to the spherical primary particles connecting by organic amines with two or more amine groups with distances between them longer thanca.4 Å. On the contrary, the formation of ISNPs would be attributed to the adsorption of two amine groups on the same primary particles, or to steric hindrance that prevent their connection.

Urodele amphibian newt bridges the missing link in evo-devo of the pancreas.

The pancreas exhibits diverse structures and roles across vertebrates. The pancreas has evolved to include both endocrine and exocrine cells, a change that occurred during the transition from fish to amphibian. This event emphasizes the evolutionary significance of amphibians. However, research has focused predominantly on anuran amphibians, with urodeles, such as newts, remaining underexplored. In this study, we investigated the development of the pancreas using Pleurodeles waltl as a model species of urodele. The newt pancreas consists of a single organ with exocrine tissue characterized by acinar structures and endocrine tissue forming islets. Notably, the newt possesses unique pancreas-like tissues on their intestines. We found that disruption of the newt Pancreatic and Duodenal Homeobox (Pdx) 1 gene resulted in an underdeveloped pancreas. Conversely, disruption of the Pdx2 paralog in newt had no significant impact on pancreatic development. The newt pancreas shows a morphology similar to that of the mammalian pancreas, which includes both exocrine and endocrine tissues. These results highlight the intermediate evolutionary position of the newt in the context of the evolution of pancreatic development. Our findings indicate that characterization of the newt pancreas will be crucial for understanding the evolutionary progression of pancreatic function in vertebrates.

Secondary Metabolites from Tripterygium wilfordii Hook. f.‐Associated Endophytes: Producing Microbes, Structures and Bioactivities

Endophytes have been recognized as important sources for discovering novel bioactive natural products with diverse structures and biological activities. This review focuses on the endophytes of Tripterygium wilfordii Hook. f. (T. wilfordii), a famous traditional medicinal plant, and summarizes the producing microbes, chemical diversities, and bioactivities of the metabolites discovered from the T. wilfordii ‐associated endophytes over the past thirty years (1995‐2024). One hundred and one metabolites together with their bioactivities from twelve endophytes are systematically reviewed. A comprehensive comparison of the 101 metabolites with those isolated from T. wilfordii reveals that the T. wilfordii‐associated endophytes produce structurally distinct metabolites with diverse biological activities. To the best of our knowledge, this is the first holistic overview of the T. wilfordii‐associated endophytes and their secondary metabolites.

Dietary Linolenic Acid Enhances IgE Binding to Bovine α-Lactalbumin/β-Lactoglobulin and Promotes KU812 Basophil Degranulation via Upregulation of the Lyn/Syk Pathway.

Milk proteins possess an abundance of free amino groups and exhibit diverse spatial structures. During food processing, these properties facilitate their interaction with hydrophobic ligands, such as linolenic acid. Exploring the IgE and IgG binding ability of linolenic acid-milk protein complexes at different temperatures, times, and molar ratios is crucial for controlling the allergenicity of milk proteins in food processing. In this study, the results indicate that linolenic acid can enhance the allergenicity of milk proteins. Moreover, by studying Lyn, Syk, NF-κB, and MAPK family-related proteins in the IgE/FcεRI-mediated signaling pathway, it is found that linolenic acid enhances cow's milk protein sensitization through the Lyn/Syk pathway. Our findings provide a further understanding of the interaction between milk nutrients and milk protein allergenicity.

Multi-Dimensional Color Tunable Long Persistent Luminescence in Metal Halide-Based CPs Through Precise Manipulation of Electronic and Steric Effects.

Regulating strategies for long persistent luminescence (LPL) are always in high demand. Herein, a series of coordination polymers (CPs) (SUST-Z1-Z4) are fabricated using 1,10-phenanthroline derivatives involving different substituents (─H, ─CH3, ─Cl, and ─Br) as ligands, respectively. Crystallographic data demonstrate that these CPs adopt alternating arrangements of cadmium halide chains and π-conjugated ligands. Cadmium halide chains not only bring about heavy atom effects but also introduce abundant intermolecular interactions, including halogen bonding and π-π stacking, favoring the generation of stable triplet excitons. Additionally, distinct substituents featured different electron-withdrawing abilities give rise to various spatial resistances between Phen planes, thereby resulting in diverse molecular packing modes and electronic structures. Thus, their aggregated state phosphorescence lifetimes range from 6.84 ms (SUST-Z4) to 91.10 ms (SUST-Z2), and the colors are modulated from orange to red at room temperature. SUST-Z2 presents the longest-lasting RTP and the most obvious red LPL, which is derived from the weakest electron-withdrawing capability of ─CH3 in ligands. Moreover, owing to the co-existence of single molecule and aggregated triplet excitons, these CPs also realize dynamic color-tunable LPL from green/orange to yellow/red depending on the excitation wavelength, temperature, and time-evolution. Based on quite different LPL of these CPs, multiple anti-counterfeiting methods are proposed.

Dynamic Covalent Spiropyran Exchange for Rapid Structural Diversification.

Here we disclose that spiropyrans are able to undergo dynamic covalent exchange via their corresponding merocyanine isomers. In the latter, the indolinium moieties can be exchanged by a Michael-type addition-elimination sequence, in which a methylene indoline attacks a merocyanine and subsequently the initial indoline fragment is cleaved. The rate and position of the exchange equilibrium strongly depend on the reaction conditions as well as the substitution pattern on the methylene indoline fragments. Importantly, spiropyran cross exchange is catalyzed by indolinium salts and provides the opportunity for rapid in-situ structural diversification of spiropyrans. This was used as synthetic tool to access various, hitherto inaccessible spiropyrans as potential dual-color photoinitiators for xolography. Moreover, we foresee application to screen dynamic covalent libraries of spiropyrans for photochromic properties and to exploit their light-sensitivity to bias the thermal equilibrium.

Large-scale preparation of Sb3+-activated hybrid metal halides with efficient tunable emission from visible to near-infrared regions for advanced photonic applications.

Zero-dimensional metal halides with diverse structures and rich photophysical properties have been reported. However, achieving multimode dynamic luminescence and efficient near-infrared (NIR) emission under blue light excitation in a single system is a great challenge. Herein, Sb3+-doped hybrid Cd(II) halides were synthesized by a large scale synthesis process at room temperature. Compared with the poor emission of (C12H28N)2CdX4 (C12H28N = tetrapropylammonium; X = Cl and Br) and single steady-state visible light emission of (C12H28N)2SbX5, (C12H28N)2CdX4:Sb3+ exhibits efficient tunable emission from visible to NIR regions. More specifically, (C12H28N)2CdCl4:Sb3+ exhibits distinct excitation wavelength-dependent luminescence characteristics, which can change from green to white and orange emission. Parallelly, halogen substitution can regulate the optical properties of Sb3+-doped (C12H28N)2CdCl4-xBrx (x = 0-1), which enables the excitation and emission bands to exhibit a significant redshift. Thus, the efficient broad NIR emission upon 450 nm excitation was realized in (C12H28N)2CdBr4:Sb3+. In addition, we demonstrated the use of (C12H28N)2CdCl4:Sb3+ phosphors in solid state lighting, and an advanced NIR light source was fabricated by coating (C12H28N)2CdBr4:Sb3+ on a commercial blue chip (450 nm), which exhibits the most advanced photoelectric efficiency (14.67%) and output power (32.84 mW) in hybrid metal halides. Finally, we also demonstrated the use of Sb3+-activated phosphors in four-level fluorescence anti-counterfeiting and information encryption.

Constraints on axion-like particles from the gamma-ray observation of the Galactic Center

High energy photons originating from the Galactic Center (GC) region have the potential to undergo significant photon-axion-like particle (ALP) oscillation effects, primarily induced by the presence of intense magnetic fields in this region. Observations conducted by imaging atmospheric Cherenkov telescopes have detected very high energy gamma-rays originating from a point source known as HESS J1745-290, situated in close proximity to the GC. This source is conjectured to be associated with the supermassive black hole Sagittarius A*. The GC region contains diverse structures, including molecular clouds and non-thermal filaments, which collectively contribute to the intricate magnetic field configurations in this region. By utilizing a magnetic field model specific in the GC region, we explore the phenomenon of photon-ALP oscillations in the gamma-ray spectrum of HESS J1745-290. Our analysis does not reveal any discernible signature of photon-ALP oscillations, yielding significant constraints that serve as a complement to gamma-ray observations of extragalactic sources across a broad parameter region. The uncertainties arising from the outer Galactic magnetic field models have minor impacts on our results, except for ALP masses around 10-7 eV, as the dominant influence originates from the intense magnetic field strength in the inner GC region.

Ingenane diterpenoids with anti-inflammatory activity from Euphorbia antiquorum.

The Euphorbia plants are famous for their diterpenoid constituents with diverse structures and broad biological activities. Herein, the discovery of 15 ingenane diterpenoids including 10 previously unreported ones (1-10) from Euphorbia antiquorum was presented. Structures of the undescribed compounds were established via detailed spectroscopic analyses. Meanwhile, a preliminary anti-inflammatory screening revealed that compound 6 showed significant inhibitory activity against the production of nitric oxide, as well as downregulated the expression of COX-2 and IL-6, in lipopolysaccharide-stimulated RAW264.7 macrophages. Further mechanistical exploration revealed that compound 6 could exert its anti-inflammatory effect by inhibiting NF-κB and activating Nrf2 signaling pathways.

A Brief Review on Recent Developments in Diels-Alder Reactions.

The [4+2] Diels-Alder cycloaddition has been widely used for the synthesis of six-mem-ber scaffolds. In recent years, there have been significant developments in this area, including the discovery and design of novel dienes and dienophiles with improved reactivity and selectivity. These new building blocks can be used to develop diverse molecular structures with functional group compatibility. Additionally, there is the use of catalytic systems and metal-mediated reactions to enable asymmetric [4+2] cycloadditions, resulting in enantiomerically enriched products. Over-all, recent studies related to [4+2] Diels-Alder cycloaddition using numerous dienes, dienophiles, and catalysts in different reaction conditions have significantly improved the efficiency, selectivity, and versatility of the reaction, making it an increasingly important tool in the synthesis of complex organic molecules as presented in this review. These advancements offer exciting possibilities for the development of new methods and reagents for the construction of six-membered rings and the synthesis of bioactive compounds.

Knowledge distillation of neural network potential for molecular crystals.

Organic molecular crystals exhibit various functions due to their diverse molecular structures and arrangements. Computational approaches are necessary to explore novel molecular crystals from the material space, but quantum chemical calculations are costly and time-consuming. Neural network potentials (NNPs), trained on vast amounts of data, have recently gained attention for their ability to perform energy calculations with accuracy comparable to quantum chemical methods at high speed. However, NNPs trained on datasets primarily consisting of inorganic crystals, such as the Materials Project, may introduce bias when applied to organic molecular crystals. This study investigates the strategies to improve the accuracy of a pre-trained NNP for organic molecular crystals by distilling knowledge from a teacher model. The most effective knowledge transfer was achieved when fine-tuning using only soft targets, i.e., the teacher model's inference values. As the ratio of hard target loss increased, the efficiency of knowledge transfer decreased, leading to overfitting. As a proof of concept, the NNP created through knowledge distillation was used to predict elastic properties, resulting in improved accuracy compared to the pre-trained model.