Structural Characterization Research Articles

Customizing Bonding Affinity with Multi‐Intermediates via Interfacial Electron Capture to Boost Hydrogen Evolution in Alkaline Water Electrolysis

AbstractDeveloping efficient and earth‐abundant alkaline HER electrocatalysts is pivotal for sustainable energy, but co‐regulating its intricate multi‐step process, encompassing water dissociation, OH− desorption, and hydrogen generation, is still a great challenge. Herein, we tackle these obstacles by fabricating a vertically integrated electrode featuring a nanosheet array with prominent dual‐nitride metallic heterostructures characterized by impeccable lattice matching and excellent conductivity, functioning as a multi‐purpose catalyst to fine‐tune the bonding affinity with alkaline HER intermediates. Detailed structural characterization and theoretical calculation elucidate that charge redistribution at the heterointerface reduces the O p‐W d and H s‐W d interactions vs. single nitride, thereby enhancing OH− transfer and H2 release. As anticipated, the resulting WN‐NiN/CFP catalyst demonstrates a gratifying low overpotential of 36.8 mV at 10 mA/cm2 for alkaline HER, while concurrently maintaining operational stability for 1300 h at 100 mA/cm2 for overall water splitting. This work presents an effective approach to meticulously optimize multiple site‐intermediate interactions in alkaline HER, laying the foundation for efficient energy conversion.

The potent PHL4 transcription factor effector domain contains significant disorder.

The phosphate-starvation response transcription-factor protein family is essential to plant response to low-levels of phosphate. Proteins in this transcription factor (TF) family act by altering various gene expression levels, such as increasing levels of the acid phosphatase proteins which catalyze the conversion of inorganic phosphates to bio-available compounds. There are few structural characterizations of proteins in this TF family, none of which address the potent TF activation domains. The phosphate-starvation response-like protein-4 (PHL4) protein from this family has garnered interest due to the unusually high TF activation activity of the N-terminal domain. Here, we demonstrate using solution nuclear magnetic resonance (NMR) measurements that the PHL4 N-terminal activating TF effector domain is mainly an intrinsically disordered domain of over 200 residues, and that the C-terminal region of PHL4 is also disordered. Additionally, we present evidence from size-exclusion chromatography, diffusion NMR measurements, and a cross-linking assay suggesting full-length PHL4 forms a trimeric or tetrameric assembly. Together, the data indicate the N- and C-terminal disordered domains in PHL4 flank a central folded region that likely forms the ordered oligomer of PHL4. This work provides a foundation for future studies detailing how the conformations and molecular motions of PHL4 change as it acts as a potent activator of gene expression in phosphate metabolism. Such a detailed mechanistic understanding of TF function will benefit genetic engineering efforts that take advantage of this activity to boost transcriptional activation of genes across different organisms.

Enhancing zT in Organic Thermoelectric Materials through Nanoscale Local Control Crystallization.

Organic thermoelectric materials are promising for wearable heating and cooling devices, as well as near-room-temperature energy generation, due to their nontoxicity, abundance, low cost, and flexibility. However, their primary challenge preventing widespread use is their reduced figure of merit (zT) caused by low electrical conductivity. This study presents a method to enhance the thermoelectric performance of solution-processable organic materials through confined crystallization using the lithographically controlled wetting (LCW) technique. Using PEDOT as a benchmark, we demonstrate that controlled crystallization at the nanoscale improves electrical conductivity by optimizing chain packing and grain morphology. Structural characterizations reveal the formation of a highly compact PEDOT arrangement, achieved through a combination of confined crystallization and DMSO post-treatment, leading to a 4-fold increase in the power factor compared to spin-coated films. This approach also reduces the thermal conductivity dependence on electrical conductivity, improving the zT by up to 260%. The LCW technique, compatible with large-area and flexible substrates, offers a simple, green, and low-cost method to boost the performance of organic thermoelectrics, advancing the potential for sustainable energy solutions and advanced organic electronic devices.

Purification, structural characterization and antioxidant mechanism of Noni polysaccharide based on Nrf2/HO-1/NQO1 signaling pathway

Purification, structural characterization and antioxidant mechanism of Noni polysaccharide based on Nrf2/HO-1/NQO1 signaling pathway

Structural characterization and species composition of mangrove vegetation in Lhokseumawe, Indonesia: Insight from multivariate analysis

The structure of the plant community significantly influences the equilibrium of the surrounding environment, affecting the trophic interactions within its ecosystem. The investigation of mangrove vegetation in Cut Mamplam village was carried out in September 2021 to determine the condition and structural characteristics of the mangrove ecosystem by multivariate analysis. The mangrove vegetation in Cut Mamplam Village was sampled at three observation stations by establishing a transect parallel to the coast. Subsequently, the community structure was examined and assessed using cluster analysis and nonmetric multidimensional scaling using the PRIMER v7 software. The study findings indicate that the mangrove forest vegetation in Cut Mamplam Village consists of five species from three families. Avicennia alba, A. lanata, Bruguiera gymnorrhiza, Rhizophora mucronata and Sonneratia alba. The highest density of mangrove vegetation was observed in A. alba in all categories: trees (616.67 ind/ha), seedlings (833.33 ind/ha) and saplings (66666.67 ind/ha). Additionally, the highest important value index (IVI) was recorded in A. alba for all categories: trees (232.16%), seedlings (102.40%), and saplings (228.43%). A similarity of mangrove density between species was noted at 60%, resulting in the formation of two distinct groups. Regarding the basal area, the vegetation stands of A. alba and A. lanata exhibited the highest values (280.61 and 266.03 m2/ha, respectively). The similarity of basal area among the observed species was 20%, resulting in the formation of two distinct groups. Additionally, Station II, classified as having mature vegetation, demonstrated a maturity similarity of 80% between observation stations.

High‐Performance MCNTs@MoS2(1‐x)Se2x Nanocomposites in Catalytic Hydrogen Evolution

AbstractAdvances in electrocatalysis require the development of high specific surface area materials with high electron conductivity. In this study, a series of MCNTs@MoS2(1‐x)Se2x nanocomposites has been prepared for application in catalytic hydrogen evolution. A uniform growth of MoS2(1‐x)Se2x nanoflower spheres on MCNTs has been achieved, circumventing stacking and aggregation. The introduction of the conducting material accelerated the electron transport rate in the electrode reaction. Structural characterization has confirmed that S doping increased the specific surface area of the catalyst, exposing more edge defects. As a result, the MCNTs@MoS2(1‐x)Se2x nanocomposites exhibited enhanced catalytic activity. Electrochemical tests have established that MCNTs@MoS1.5Se0.5 possessed the lowest overpotential (146 mV) at a current density of 10 mA/cm2 with the smallest Tafel slope (45.1 mV/dec).

New thiophene derivatives: chemoselective synthesis, antitumor effectiveness, structural characterization, DFT calculations, Hirshfeld surface, and Fukui function analysis.

In this study, the chemoselective synthesis of two new thiophene derivatives is presented. The structure of newly synthesized thiophenes derivatives; ethyl 4-acetyl-3-phenyl-5-(phenylamino)thiophene-2-carboxylate (5) and ethyl (E)-4-(3-(dimethylamino)acryloyl)-3-phenyl-5-(phenylamino)thiophene-2-carboxylate (8) were established using different FTIR and NMR spectral analyses. Compound 8 was isolated as single crystal and its 3D structure was determined using X-ray crystallographic analysis. Possible intermolecular interactions that control the molecular packing of 8 were elucidated using Hirshfeld topology analysis. The O…H (13.7%), H…H (55.3%) and C…C (2.3%) intermolecular interactions are the most significant. Fukui functions showed that C4 in thiophene 5 and C3 in thiophene 8 are the most reactive atoms for nucleophilic attack, while N9 in thiophene 5 and C1 in thiophene 8 are the most reactive atoms for electrophilic attack. Antitumor activity of thiophene 5 was assessed and the results showed higher activity against HepG-2 (7.46µg/mL) compared to the HCT 116 (12.60µg/mL) cell line.

Conformally printed additively manufactured RF demonstrator for circuit compaction

Abstract Recently, there has been interest in applying Additive Manufacturing (AM) to RF and Microwave applications, especially in packaging of microelectronic devices. Additive packaging offers advantages of expanded functionality in restricted volume, through miniature, low-SWaP-C sensors, allowing for non-traditional form factors. In this work, design, fabrication, and characterization of a non-planar multi-material MMIC structure is presented to demonstrate significant footprint reduction and circuit compaction. Performance of a non-planar passive RF device and details of planar to non-planar AM connections for characterization of the transitions will be demonstrated. The work will present details of the design and fabrication of the non-planar structure, optimization of the process parameters for the Optomec 5-axis Aerosol Jet Printer for multi-material printing, and the results of the characterization and testing. RF measurements were conducted to demonstrate the functionality of the developed non-planar circuit and compared with simulations which showed good agreement. The results of this work show that fully additive approach is feasible for non-planar circuits, which will allow for footprint reduction, weight reduction, and achievement of novel form factors that are critical for microwave applications.

Two‐Phase Extraction, Structural Characterization of the Polysaccharide from Raspberry Pomace and Its Protection Effects against Erythrocyte Hemolysis

AbstractIn present study, a new polysaccharide (RPP) from raspberry pomace is prepared through ultrasound‐assisted aqueous two‐phase extraction (UAATPE) and purification using two‐step column chromatography, the extraction conditions are optimized by response surface method (RSM). Under the optimal parameters: liquid to material ratio of 80 mL g−1, ultrasonic power of 340 W, and ultrasonic time of 39 min, the yield of the polysaccharides is 11.72 ± 0.05%. RPP with average molecular weight (Mw) of 59 300 Da is composed of six monosaccharides. Nuclear magnetic resonance (NMR) analyses confirmed that RPP contains six main glycosidic linkages including α‐l‐Araf‐(1→, →2)‐α‐l‐Rhap‐(1→, →4)‐β‐d‐Manp‐(1→, →4)‐α‐d‐GalAp‐(1→, →3)‐β‐d‐Galp‐(1→, →4)‐β‐d‐Glcp‐(1→. RPP exhibits remarkable protective effects against H2O2‐induced erythrocyte hemolysis, the generations of reactive oxygen species, and malondialdehyde are inhibited, and the activities of glutathione peroxidase and catalase are effectively enhanced. The current findings proved that UAATPE is an effective method to extract the polysaccharide from raspberry pomace and provides a new idea for the utilization of nutrient‐rich raspberry fruit residue.

Cepathiolactols and Cepathiolactones─Two Newly Discovered Families of Organosulfur Compounds Fored in Cut Onion.

Isolation and structural characterization of two large families of organosulfur compounds spontaneously formed upon cutting of onion (Allium cepa) were carried out. The structures of these hitherto unknown species, trivially named cepathiolactols and cepathiolactones, were established based on NMR, MS, and IR data. It was found that cepathiolactols (CxHyOS3 and CxHyO2S4; x = 7-12, y = 14-24) are 3,4-dimethyl-γ-thiolactols bearing various side chains linked via a disulfanyl moiety at position C-5. On the other hand, cepathiolactones were shown to be 3,4-dimethyl-γ-thiolactones structurally analogous to cepathiolactols. Sensory properties of cepathiolactols were also evaluated, along with testing their ability to participate in the formation of pink discoloration of processed onion.

Structural characterization and anti-fatigue mechanism based on the gut-muscle axis of a polysaccharide from Zingiber officinale.

This study aimed to characterize the structure of polysaccharide ZOPA extracted from Zingiber officinale and its purified form (ZOPA-1), and to investigate their anti-fatigue mechanisms based on the gut-muscle axis. The study found that the backbone of ZOPA-1 is primarily composed of →3,4)-α-Glcp-1→ and →4,6)-α-Glcp-(1→ linkages, with →4)-α-Glcp(1→ serving as its side chain. In exhaustive swimming experiments with mice, both crude ZOPA and purified ZOPA-1 demonstrated significant anti-fatigue effects, including enhanced glycogen storage, improved antioxidant capacity, reduced accumulation of metabolic waste products, and regulated energy metabolism in the gastrocnemius muscles. These effects may be mediated through the activation of the Keap1-Nrf2/ARE and AMPK/PGC-1α signaling pathways. Furthermore, ZOPA and ZOPA-1 modulated the intestinal flora of mice, increasing diversity, altering abundance, and regulating short-chain fatty acid concentrations, suggesting a potential role of the gut-muscle axis in mediating the anti-fatigue effects. This study provides valuable insights into the complex interplay between polysaccharides, the gut-muscle axis, and exercise-induced fatigue.

Structural Characterization and Profiles of Saponins from Two Algerian Sea Cucumbers

Sea cucumbers are benthic marine invertebrate members of the phylum Echinodermata. Due to the absence of a rigid skeleton, these species have developed chemical defenses based on the production of saponins (triterpene glycosides). These secondary metabolites are bioactive molecules with a broad biological, ecological, and pharmaceutical spectrum. However, the saponin profiles of several species of sea cucumbers are not known yet. The present study aims to highlight the mixture of saponins in two sea cucumber species from the Algerian coast, namely Holothuria (Holothuria) algeriensis, which has been recently described in central and western Algerian waters, and Holothuria (Roweothuria) arguinensis, originating from the Atlantic Ocean and reported in Algeria for the first time in 2014. Saponin extracts from three individuals of H. (H.) algeriensis and two individuals of H. (R.) arguinensis were analyzed using mass spectrometry, i.e., Matrix-assisted Laser Desorption/Ionization mass spectrometry (MALDI-MS), MALDI-High Resolution MS (MALDI-HRMS), Liquid Chromatography MS (LC-MS) and tandem MS (LC-MS/MS). These analyses allow us to detect 11 and 18 elemental compositions for H. (H.) algeriensis and H. (R.) arguinensis, respectively, each presenting several isomers. In total, 13 new saponin structures are proposed, of which four are common between the two species, six are specific to H. (H.) algeriensis and three to H. (R.) arguinensis. The saponin profiles of the two species were compared to those of other species of the same genus existing on the Algerian coast and the results showed that they share non-sulfated saponins with Holothuria (Panningothuria) forskali and Holothuria (Platyperona) sanctori and sulfated saponins with Holothuria (Holothuria) tubulosa and Holothuria (Roweothuria) poli.

Extraction, purification, structural characterization, bioactivities, modifications and structure–activity relationship of polysaccharides from Ophiopogon japonicus: a review

Ophiopogon japonicus (Thunb.) Ker Gawl., is a traditional Chinese medicine (TCM) with a history of thousands of years. O. japonicus polysaccharides (OJPs), as one of the main active ingredient, are a kind of representative pharmacological bioactive macromolecules and mainly composed of Glc and Fru with molecular weight between 2.48 and 325 kDa. OJPs have a variety of biological activities, such as hypoglycemic, cardioprotective, immunomodulatory, improvement of obesity, and renal protective activity. In this review, the extraction, purification and structural characterization of OJPs were systematically reviewed, and its biological function, molecular mechanism and structure–activity relationship were analyzed. Additionally, this review summarized and found that structural modifications such as liposome modification, sulfation modification, and polyethylene glycol modification have improved the pharmacological activity and bioavailability of OJPs. Overall, this work will help to better understand OJPs and provide a theoretical review of their further development and utilization in the field of medicine and health food.

Fracture mode classification of UHPC based on deep learning and wavelet time–frequency spectrum derived from acoustic emission waveform

Fracture mode categorization is essential in identifying the failure stage, evaluating the damage characteristics, and providing references for structural maintenance. Acoustic emission (AE), as a passive nondestructive technique, presents great potential in damage characterization of cementitious materials and structures. In this study, a convolutional neural network (CNN) and gated recurrent unit (GRU) integrated model for tensile, shear, and mixed cracking mode classification of ultra-high-performance concrete (UHPC) was proposed and verified based on AE waveform features. First, four-point bending and direct shear tests for UHPC specimens were carried out, respectively, to generate AE waveform signals corresponding to different cracking modes (tensile, shear, and mixed ones). Subsequently, the collected one-dimensional AE signals were converted into two-dimensional time–frequency spectrum by continuous wavelet transform. And an AE dataset was constructed after manual labeling based on the corresponding relationships between cracking modes and wavelet time–frequency spectra. Then, an automatic CNN-GRU automatic classification model was established using wavelet time–frequency spectrum images as input variables, where the CNN extracts spatial image features, and the GRU screens time dependencies and realizes final classification. The proposed CNN-GRU model achieves an accuracy of 96.17% for cracking mode classification of UHPC, which is superior both in computational accuracy and efficiency to lightweight CNN and AlexNet. Classification outcomes for UHPC specimen under four-point bending and direct shear tests revealed the proportion of tensile cracks progressively decreased with the increase of damage, while shear cracks exhibited the opposite trend. The percentage of mixed mode cracks maintained relatively stable throughout the failure stages. The model proposed in this study presents favorable performance to reveal the underlying damage evolution mechanism during UHPC fracture, which can also provide references for the cracking mode classification of other cementitious materials and structures.

Construction of Mo-Doped CuO Incorporated on Carbon Black Modified Disposable Sensor for the Voltammetric Detection of Metol in Environmental Samples

Abstract In this study, a molybdenum-doped copper oxide (Mo–CuO) composite was synthesized via a hydrothermal method and combined with carbon black (CB) to form Mo–CuO@CB. This composite was used to modify a screen-printed carbon electrode (SPCE) for the detection of Metol (MT), an industrial pollutant harmful to both human health and the environment. Structural and surface characterization was performed using high-resolution transmission electron microscopy, field-effect scanning electron microscopy, energy-dispersive spectroscopy, Raman spectroscopy, X-rssy photoelectron spectroscopy, and X-ray diffraction. Electrochemical techniques, including differential pulse voltammetry and cyclic voltammetry, were used to assess the sensor's performance. The Mo–CuO@CB@SPCE sensor exhibited a low detection limit of 2.7 nM, and limit of quantification is 82 nM, a broad linear range (5.0 × 10−9 – 170 mol L-1), and high sensitivity (4.148 μA μM⁻¹ cm⁻²), benefiting from the catalytic activity of Mo–CuO and the large surface area of CB. With recovery rates ranging from 96 % to 100.6% in pond, river, and tap water, the sensor effectively detects MT in environmental samples, ensuring reliable monitoring of this persistent pollutant.

Zn-Modified TiO2 Thin-Films for Real-Time Formaldehyde Sensing at Room Temperature

Abstract This study explores the fabrication and application of zinc-modified titanium dioxide (Zn-TiO2) thin-films for real-time recognition of volatile organic compounds (VOCs), with a particular emphasis on formaldehyde (HCHO) sensing at room temperature. The Zn-TiO2 thin-films were produced using an economical spray-pyrolysis method. Structural, morphological, and optical characterizations confirmed the successful integration of zinc with varied Wt.% (0, 2, 4, and 6) into the TiO2 lattice. The real-time monitoring capabilities of the sensors were assessed against a range of VOCs, highlighting its specificity for formaldehyde detection amidst diverse environmental constituents. The fabricated thin film sensors with zinc dopant were optimized to enhance the sensor's performance. 4 Wt.% Zn-TiO2 demonstrated excellent sensitivity to formaldehyde vapor at ambient conditions, showcasing a rapid and selective response. The underlying sensing mechanism was explored, emphasizing the role of zinc doping in tailoring the material's surface properties and facilitating enhanced adsorption of formaldehyde molecules. The study underscores the potential of Zn-modified TiO2 thin films as a reliable and efficient platform for real-time VOC monitoring, with a specific focus on HCHO sensing at room-temperature. The sensor shows remarkable stability and repeatability, making it a promising candidate for continuous monitoring applications.

Structural Diversity of Cadmium Complexes with N‐Heterocyclic Carbene‐Isothiocyanate Zwitterionic Ligand

In this study, we discuss the synthesis and structural characterization of three N‐heterocyclic carbene isothiocyanate zwitterionic ligands, 1,3‐bis(2,6‐diisopropylphenyl)‐2‐N‐phenyl‐thiocarbamoyl imidazolium (ImDipp ‐CSNPh, L1), 1,3‐bis(tert‐butyl)‐2‐N‐phenylthiocarbamoyl imidazolium (ImtBu‐CSNPh, L2) and 1,3‐bis(2,4,6‐trimethylphenyl)‐2‐N‐phenylthiocarbamoyl imidazolium (ImMes‐CSNPh, L3) and their cadmium complexes, [(ImDipp‐CSNPh)2CdCl][CdCl3] (1) and [(ImtBu‐CSNPh)2Cd2Cl6] (2). Both bench‐stable cadmium complexes were synthesized by directly reacting the corresponding NHC‐CSNPh adducts with anhydrous cadmium chloride. The solid‐state structures of zwitterionic NHC‐isothiocyanate betaine adducts (L1‐L3) and cadmium complexes (1 and 2) were investigated with the assistance of single crystal X‐ray diffraction analysis. A steric modification of N‐substituent on NHC governs a unique structural change from betaine ImDipp‐CSNPh coordinated cationic cadmium complex to neutral dimeric cadmium complex with ImtBu‐CSNPh.

Structural Characterization and Bioactive Compound Evaluation of Fruit and Vegetable Waste for Potential Animal Feed Applications

Agricultural waste from the fruit and vegetable industry is used as an alternative source of animal feed, but detailed investigations are required. The aim of this work was to conduct a physico-chemical characterization, through analytical techniques, of fruit and vegetable wastes such as those of golden apples, red apples, carrots, celery, beetroots, and red potato peels. The bioactive compounds in the samples indicated a high carbohydrate content of 50.38 g/100 g in golden apples and 59.38 mg/100 g of organic acids in celery. In addition, the total phenolic content (TPC, mg gallic acid equivalent/g dry weight) varied between 3.72 in celery and 15.51 in beetroots. The antioxidant capacity values were significant. A thermal analysis showed thermal stability and weight loss, underscoring the composition of the solid samples. An infrared spectroscopy (FTIR) analysis showed C-H, O-H, C=O, and N-H functional groups in non-starchy carbohydrates, organic acids, and proteins. Microscopic techniques revealed the microstructure, particle size, and semicrystalline profile of the samples. The ultrastructure (determined via atomic force microscopy (AFM)) of celery consisted of a smooth and uniform surface with a lignin and cellulose texture. These results highlight the importance of fruit and vegetable waste as an alternative source of essential nutrients and bioactive compounds for animal feed.

A Hexanuclear Gallium(III) Complex with a {GaIII6(μ‐OH)10} Core Supported by Two Naphthalenediolate‐Based Ligands

AbstractWe have developed a family of 2,7‐disubstituted 1,8‐naphthalenediol ligands to pre‐organize two metal ions to the distance of two neighboring phosphate diesters of 6–7 Å in the DNA backbone by a rigid backbone. As complexes with divalent ions (CuII and NiII) bind to DNA, interferes DNA synthesis via PCR, and kills human cancer cells more efficiently than human stem cells of the same proliferation rate, we intended to increase the binding affinity by going from divalent to trivalent ions‐especially FeIII. Here, we apply GaIII as redox inactive model for FeIII and obtain for the first time a complex with trivalent ions. However, the structural characterization provides not a dinuclear GaIII complex, but a hexanuclear GaIII complex with a central {GaIII6(μ‐OH)10} core, that is yet unprecedented.

Structural characterization and physicochemical properties of different hydrophilic natural deep eutectic solvents.

To overcome the toxic nature of organic solvents, scientific interest in the use of green solvents, particularly natural deep eutectic solvents (NADES), has increased over the past decade, leading to new applications in the food, nutraceutical, pharmaceutical, and cosmetic industries. Understanding the physicochemical properties and molecular interactions of NADES is essential for uncovering new potential applications in these fields. In this study, several lactic and citric acid-based NADES, as well as chloride choline- and urea-based NADES, were evaluated for their physicochemical properties, including density, pH, viscosity, conductivity, and refractive index. Additionally, nuclear magnetic resonance (NMR), and in particular nuclear Overhauser enhancement spectroscopy (NOESY), was employed to investigate the intermolecular interactions between the NADES components to confirm the formation of the eutectic mixture. The extraction efficiency of the confirmed NADES was tested for extracting polyphenols as a proof of concept to highlight their relationship with the measured properties. Lactic and choline chloride-based NADES provided the highest extraction yields. These results were also compared with the predicted extraction capabilities of each NADES provided by the COSMO-RS software.