Formation Of Structure Research Articles

Possible involvement of three-stemmed pseudoknots in regulating translational initiation in human mRNAs.

RNA pseudoknots play a crucial role in various cellular functions. Established pseudoknots show significant variation in both size and structural complexity. Specifically, three-stemmed pseudoknots are characterized by an additional stem-loop embedded in their structure. Recent findings highlight these pseudoknots as bacterial riboswitches and potent stimulators for programmed ribosomal frameshifting in RNA viruses like SARS-CoV2. To investigate the possible presence of functional three-stemmed pseudoknots in human mRNAs, we employed in-house developed computational methods to detect such structures within a dataset comprising 21,780 full-length human mRNA sequences. Numerous three-stemmed pseudoknots were identified. A selected set of 14 potential instances are presented, in which the start codon of the mRNA is found in close proximity either upstream, downstream, or within the identified three-stemmed pseudoknot. These pseudoknots likely play a role in translational initiation regulation. The probability of their existence gains support from their ranking as the most stable pseudoknot identified in the entire mRNA sequence, structural conservation across homologous mRNAs, stereochemical feasibility as demonstrated by structural modeling, and classification as members of the CPK-1 pseudoknot family, which includes many well-established pseudoknots. Furthermore, in four of the mRNAs, two or three closely spaced or tandem three-stemmed pseudoknots were identified. These findings suggest the frequent occurrence of three-stemmed pseudoknots in human mRNAs. A stepwise co-transcriptional folding mechanism is proposed for the formation of a three-stemmed pseudoknot structure. Our results not only provide fresh insights into the structures and functions of pseudoknots but also unveil the potential to target pseudoknots for treating human diseases.

Effects of Zr, Al, and Al+Zr Addition on Phase Evolution Characteristics and Strengthening Mechanisms of Fe‐42Ni‐2Y2O3 Oxide Dispersion Strengthening Steels Developed by Mechanical Alloying and Spark Plasma Sintering

In the present study, Fe‐42 wt% Ni‐2 wt% Y2O3 super‐invar‐based steels have been explored to study the effects of Zr, Al, and Zr+Al addition on phase evolution, strengthening mechanisms, and mechanical behavior. Three different compositions, such as Fe‐42Ni‐2Y2O3‐2Zr (2YZr), Fe‐42Ni‐2Y2O3‐2Al (2YAl), and Fe‐42Ni‐2Y2O3‐2Zr‐2Al (2YAlZr), are developed by mechanical alloying (MA) followed by spark plasma sintering (SPS) at 1100 °C with an applied pressure of 60 MPa. The 2YZr alloy after SPS shows the evolution of a uniform grain size of ≈1.7 μm, whereas 2YAl reveals the formation of bimodal grain structure sintered under the same condition. Conversely, the combined effect of Al and Zr addition results in the evolution of ultrafine grained structure (≈380 nm) after SPS at the same condition (i.e., at 1100 °C). The superior mechanical strength of the 2YAlZr alloy (5.3 GPa/1415 MPa) is attributed to the evolution of uniformly dispersed extremely fine (60 nm) high‐density Al‐ and Zr‐rich oxide complexes in the ultrafine grained matrix. The analysis of strengthening contributions to the yield strength is found to be correlated well with the experimental results and attributed to the morphology of microstructural constituents, their stability, and volume fraction of dispersoids in the matrix.

Low-Temperature Plasma-Constructed Ni-Doped W18O49 Nanorod Arrays for Enhanced Electrocatalytic Oxygen Evolution and Urea Oxidation.

Surface engineering by doping and amorphization is receiving widespread attention from the perspective of the regulation of the electrocatalytic activities of electrocatalysts. However, the effective modulation of active sites on catalysts is still challenging. Herein, a straightforward and efficient method combining hydrothermal treatment with low-temperature plasma processing is presented to synthesize Ni-doped W18O49 nanorod arrays on carbon cloth with abundant oxygen vacancies (CC/WO-Ni-x). Mild plasma doping with Ni modifies the electronic structure of the W18O49 nanorod arrays, resulting in the formation of an amorphous structure that significantly reduces the electron transfer resistance. Additionally, the coupling with high-valent W6+ (derived from W18O49) leads to the partial preoxidation of doped Ni to form active Ni3+ species and oxygen vacancies. These features are collectively responsible for the remarkable oxygen evolution reaction (OER) and urea oxidation reaction (UOR) properties of CC/WO-Ni-4, for example, 10 mA cm-2 current density, an overpotential of 265 mV required for the OER under 1.0 M KOH solution. The addition of 500 mM urea to the 1.0 M KOH solution decreases the overpotential required for the same current density from 265 to 93 mV. This study provides insights into the modification of surface structures and presents an effective strategy to optimize the electrocatalytic active sites and enhance the efficiency of multifunctional electrocatalysts.

Elucidating the mechanism of inulin-induced improvement in the structural and functional properties of High-moisture extruded products

High-moisture extrusion (HME) has increasingly garnered attention in the production of plant-based meat analogs. Nevertheless, the disorganized structural properties and poor functional characteristics of HME extrudates pose significant challenges to the advancement of plant-based alternatives in the food industry. The coextrusion of proteins and polysaccharides has emerged as an effective strategy to improve the sensory qualities of HME meat analogs. Herein, we investigated the effects of the type and addition of inulin on the structural and functional properties of HME extrudates comprising soy protein isolate, soy protein concentrate, and wheat protein. The results indicated that inulin facilitated the conversion of 7S to 11S globulin and induced a transformation from a β-turn angle to a β-folded protein structure, promoting lamellar structure formation and enhancing the overall stability of the protein matrix. Optimal results were achieved with the addition of 6% long-chain and short-chain inulin. In terms of functional characteristics, the incorporation of short-chain inulin resulted in a superior fiber structure and protein digestibility, whereas long-chain inulin enhanced the water-holding capacity, rehydration rate, and thermal stability. Additionally, intermolecular interaction analysis revealed that these inulin-induced improvements in the quality of HME extrudates are primarily attributed to the strengthening of disulfide bonds and hydrogen bonds. These findings offer crucial insights for advancing the quality of plant-based meat analogs, providing valuable directions for future product development in the food industry.

Exploring the effect of Hf (IV) doping in spinel ferrite CoHfxFe2-xO4 on magnetic properties, electrochemical impedance, and photocatalytic activity: In-depth structural study

In this study, CoHfxFe(2−x)O4 nanoparticles (x = 0.0, 0.04, 0.08, and 0.12) were synthesized using the co-precipitation method. X-ray diffraction (XRD) analysis confirmed a pure spinel phase for the x = 0.04 sample, validated by Rietveld refinement, with crystallite sizes between 39 and 59 nm. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the formation of the spinel structure and the proper valence states of the elements. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) verified the morphology and homogeneity of the samples. Magnetic property analysis revealed reduced saturation magnetization with increased Hf content. Impedance spectroscopy showed enhanced electrical resistivity with Hf incorporation. Photocatalytic tests demonstrated that doping improves the degradation efficiency of Orange G dye under UV-Vis irradiation, achieving yields between 9 % and 35 % after 60 min.

Formation of lamellar eutectic structure and improved mechanical properties of directional solidified Al0.9CoCrNi2.1 high-entropy alloy

In this study, Al0.9CoCrNi2.1 EHEA was prepared by directional solidification at various withdrawal rates from 6 to 120 μm/s. The lamellar eutectic structure is formed containing FCC (L12) and BCC (B2) at different withdrawal rates during directional solidification. The solid-liquid interface of the alloy transfers from nearly-planer to cellular eutectic interface and the lamellar spacing decreases from 7.17 μm to 1.65 μm as the withdrawal rate increases. The lamellar spacing is negatively correlated with withdrawal rates which was identified by the Jackson-Hunt model and its growth rate index (0.484) is closely related to the theoretical value (0.5). The tensile experiment demonstrates that the structure of Al0.9CoCrNi2.1 EHEA is finer and the ultimate tensile strength and elongation increase as the withdrawal rate increases. The elongation of Al0.9CoCrNi2.1 EHEA is two times higher than that of the as-cast alloy at the withdrawal rate of 120 μm/s. It is concluded that the formation of the L12 phase and Cr-rich precipitated phases in the directional solidified eutectic structure are associated with the enhancement of mechanical properties due to grain refinement at high withdrawal rates.

Lattice Distortion Induced Ta‐doped BaTiO3 for Efficient Photocatalytic Water Splitting for Hydrogen Production

AbstractBaTiO3, as a perovskite type material with excellent chemical stability and suitable conduction, has been widely studied in the field of photocatalysis. However, it can only absorb ultraviolet light because of its wide band gap. Herein, the lifetime of photogenerated electrons of BaTiO3 doped with Ta5+ can be enhanced. To study the band structure and photocatalytic performance of Ta‐doped BaTiO3, sol‐gel assisted solid‐phase method was employed to prepare BaTiO3 doped with varying Ta5+ doping amounts, and the structure characteristic and formation mechanism of the Ta‐doped BaTiO3 were analyzed. The results showed that the heat treatment temperature reached 1052.7 °C, sufficient thermodynamic conditions were obtained for Ta5+ to dope into the BaTiO3 lattice, and lattice distortion occurred in BaTiO3. Meanwhile, the particle size after doping decreased with the increase of Ta5+ doping amount. The 1.25 mol %Ta5+‐doped BaTiO3 had the lowest band gap (3.077 eV), and the photocatalytic water splitting had the best hydrogen evolution activity, which was 2.4 times that of BaTiO3. Furthermore, the conductance potential of 1.25 mol %Ta5+‐doped BaTiO3 was more negative than that of BaTiO3, which improved the thermodynamic advantage of the photocatalytic water splitting, and it had higher and more stable photoresponse and photogenerated carrier migration rate.

Redox Concomitant Formation Method for Fabrication of Cu(I)-MOF/Polymer Composites with Antifouling Properties.

Marine biofouling, which is one of the technical challenges hindering the growth of the marine economy, has been controlled using cuprous oxide (Cu2O) nanoparticles due to the exceptional antifouling properties of Cu(I) ions. However, Cu2O nanoparticles have encountered bottlenecks due to explosive releases of Cu+ ions, high toxicity at elevated doses, and long-term instability. Here, we present a novel method called Redox Concomitant Formation (RCF) for fabricating a hierarchical Cu(I) metal-organic framework polypyrrole (Cu(I)-MOF/PPy) composite. This method enables in-situ phase transition via successive redox reactions that change the chemical valence state and coordination mode of Cu(II)-MOF, resulting in a new structure of Cu(I)-MOF while creating a PPy layer surrounded by the hierarchical structure. Owing to the steady release of Cu+ ions from the Cu(I) sites and photothermal properties of PPy, Cu(I)-MOF/PPy exhibits superior and broad-spectrum resistance to marine bacteria, algae, and surface-adhered biofilms in complex biological environments, as well as long-term stability, resulting in 100% eradication efficiency under solar-driven heating. Mechanistic insights into successive structural redox reactions and formation using the RCF method are provided in detail, enabling the fabrication of novel MOFs with the desired composition and structure for a wide range of potential applications.

Redox Concomitant Formation Method for Fabrication of Cu(I)‐MOF/Polymer Composites with Antifouling Properties

Marine biofouling, which is one of the technical challenges hindering the growth of the marine economy, has been controlled using cuprous oxide (Cu2O) nanoparticles due to the exceptional antifouling properties of Cu(I) ions. However, Cu2O nanoparticles have encountered bottlenecks due to explosive releases of Cu+ ions, high toxicity at elevated doses, and long‐term instability. Here, we present a novel method called Redox Concomitant Formation (RCF) for fabricating a hierarchical Cu(I) metal‐organic framework polypyrrole (Cu(I)‐MOF/PPy) composite. This method enables in‐situ phase transition via successive redox reactions that change the chemical valence state and coordination mode of Cu(II)‐MOF, resulting in a new structure of Cu(I)‐MOF while creating a PPy layer surrounded by the hierarchical structure. Owing to the steady release of Cu+ ions from the Cu(I) sites and photothermal properties of PPy, Cu(I)‐MOF/PPy exhibits superior and broad‐spectrum resistance to marine bacteria, algae, and surface‐adhered biofilms in complex biological environments, as well as long‐term stability, resulting in 100% eradication efficiency under solar‐driven heating. Mechanistic insights into successive structural redox reactions and formation using the RCF method are provided in detail, enabling the fabrication of novel MOFs with the desired composition and structure for a wide range of potential applications.

Suitable Stereoscopic Configuration of Electrolyte Additive Enabling Highly Reversible and High-Rate Zn Anodes.

Electrolyte additive engineering is a crucial method for enhancing the performance of aqueous zinc-ion batteries (AZIBs). Recently, most research predominantly focuses on the role of functional groups in regulating electrolytes, often overlooking the impact of molecule stereoscopic configuration. Herein, two isomeric sugar alcohols, mannitol and sorbitol, are employed as electrolyte additives to investigate the impact of the stereoscopic configuration of additives on the ZnSO4 electrolyte. Experimental analysis and theoretical calculations reveal that the primary factor for improving Zn anode performance is the regulation of the solvation sheath by these additives. Among the isomers, mannitol exhibits stronger binding energies with Zn2+ ions and water molecules due to its more suitable stereoscopic configuration. These enhanced bindings allow mannitol to coordinate with Zn2+, contributing to solvation structure formation and reducing the active H2O molecules in the bulk electrolyte, resulting in suppressed parasitic reactions and inhibited dendritic growth. As a result, the zinc electrodes in mannitol-modified electrolyte exhibit excellent cycling stability of 1600 h at 1 mA cm-2 and 900 h at 10 mA cm-2, respectively. Hence, this study provides novel insights into the importance of suitable stereoscopic molecule configurations in the design of electrolyte additives for highly reversible and high-rate Zn anodes.

Features of structural formations in butadiene-nitrile rubber films under the action of a directed electric field

Features of structural formations in butadiene-nitrile rubber films under the action of a directed electric field

Extremely large magnetoresistance in twisted intertwined graphene spirals

Extremely large magnetoresistance (XMR) is highly applicable in spintronic devices such as magnetic sensors, magnetic memory, and hard drives. Typically, XMR is found in Weyl semimetals characterized by perfect electron–hole symmetry or exceptionally high electric conductivity and mobility. Our study explores this phenomenon in a recently developed graphene moiré system, which demonstrates XMR owing to its topological structure and high-quality crystal formation. We investigate the electronic properties of three-dimensional intertwined twisted graphene spirals (TGS), manipulating the screw dislocation axis to achieve a rotation angle of 7.3°. Notably, at 14 T and 2 K, the magnetoresistance of these structures reaches 1.7 × 107%, accompanied by a metal–insulator transition as the temperature increases. This transition becomes noticeable when the magnetic field exceeds a minimal threshold of approximately 0.1 T. These observations suggest the possible existence of complex, correlated states within the partially filled three-dimensional Landau levels of the 3D TGS system. Our findings open up possibilities for achieving XMR by engineering the topological structure of 2D layered moiré systems.

Structural analysis of peptide identified from the 2KRR domain of the nucleolin protein with a c-Myc G4 structure using biophysical and biochemical methods.

For the first time, the c-Myc G4 structure is reported to be stabilized by binding of the peptide (derived from the 2KRR domain of the nucleolin protein called the Nu peptide) in the loop region of the G-quadruplex structure by stacking interactions. CD results showed the formation of parallel G4 structure in the presence of 100 mM Na+ or 100 mM K+ with the appearance of two isodichroic points at 229 nm, 254 nm and 252 nm in the presence of 100 mM Na+ or 100 mM K+, respectively. In addition, in UV thermal and CD melting studies, we observed drastic changes with an increase in the hyperchromicity at a DNA : peptide ratio of 1 : 50. On titrating the Nu peptide with c-Myc G4, we calculated the value of binding constant (K a) by plotting fluorescence intensity and DNA concentration as 0.1369 ± 0.008 μM and 0.1277 ± 0.073 μM in Na+ and K+, respectively, which confirms the strong association of Nu peptide with c-Myc G4. The Nu peptide showed preferential cytotoxicity against MDA-MB-231 cells with IC50 values of 5.020 μM and 5.501 μM after 72 and 96 hours. This approach suggests a novel strategy to target G4 structure using natural key peptide segments derived from G4 stabilizing protein.

Unraveling the mystery of sandwich structure: Emerging photocatalytic hydrogen production by g-C3N5 coupled Nb2C MXene forming Schottky heterojunction

The development of new photocatalysts and photocatalytic systems is the essence of the development of photocatalytic hydrogen production engineering. Nitrogen-rich graphite carbon nitride (g-C3N5) has gradually replaced conventional graphite phase carbon nitride (g-C3N4) with a smaller bandgap and high-efficiency visible light utilization. In this study, g-C3N5 and Nb2C MXene coupled composition with sandwich structure were manufactured by a simple ultrasonic magnetic stirring method and used for photocatalytic hydrogen production. By adjusting the ratios of single components in the system, the hydrogen production rate of the optimal sample 4:1g-C3N5/Nb2C under visible light irradiation is 2529.5 μmol·g−1·h−1, which is 21 times higher than that of g-C3N5. The high apparent quantum yield (AQY) value of 17.3 % also proves a high light utilization rate. The atomic force microscopy (AFM) technique reveals variations in the thickness of the samples, while strongly demonstrating the formation of sandwich structure. In addition, X-ray photoelectron spectroscopy (XPS) analysis further reveals the electron transfer paths within the system, preliminarily verifying the formation of Schottky heterojunctions. Kelvin probe force microscopy (KPFM) tests not only re-validate the correctness of the electron transfer path but also demonstrate the accuracy of the energy bands. The density-functional theory (DFT) calculations corroborate that Nb2C MXene plays the role of a photoco-catalyst to form Schottky heterojunctions with g-C3N5 for efficient carrier separation and migration. This work highlights the key role of sandwich structure photocatalytic systems on photocatalytic performance.

A Novel Gelatin Binder with Helical Crosslinked Network for High-Performance Si Anodes in Lithium-Ion Batteries.

Silicon(Si) is a promising anode material for lithium-ion batteries, but its large volume expansion during cycling poses a challenge for the binder design. In this study, a novel gelatin binder is designed and prepared with a helical crosslinked network structure. This gelatin binder is prepared by enzymatic crosslinking and immersion in Hofmeister salt solution, which induces the formation of network and helical secondary structures. The helical crosslinked network structure can be analogous to a spring group system to effectively dissipate the stress and strain caused by the Si expansion. The gelatin binder is further partially carbonized by low-temperature pyrolysis, which improves its conductivity and stability. The Sianode with the optimized gelatin binder exhibits high initial coulombic efficiency, excellent rate performance, and long-term cycling stability. This study provides an innovative approach for the preparation of high-performance Si anodes, namely by controlling the molecular configuration of the binder to significantly improve the cycle stability, which can also be applied to other high-capacity anode materials that suffer from large volume changes during cycling.

Self-Blinking Thioflavin T for Super-resolution Imaging.

Thioflavin T (ThT) is a typical dye used to visualize the aggregation and formation of fibrillar structures, e.g., amyloid fibrils and peptide nanofibrils. ThT has been considered to produce stable fluorescence when interacting with aggregated proteins. For single-molecule localization microscopy (SMLM)-based optical super-resolution imaging, a photoswitching/blinking fluorescence property is required. Here we demonstrate that, in contrast to previous reports, ThT exhibits intrinsic stochastic blinking properties, without the need for blinking imaging buffer, in stable binding conditions. The blinking properties (photon number, blinking time, and on-off duty cycle) of ThT at the single-molecule level (for ultralow concentrations) were investigated under different conditions. As a proof of concept, we performed SMLM imaging of ThT-labeled α-synuclein fibrils measured in air and PBS buffer.

Enhanced native chemical ligation by peptide conjugation in trifluoroacetic acid.

Chemical ligation of peptides is increasingly used to generate proteins not readily accessible by recombinant approaches. However, a robust method to ligate "difficult" peptides remains to be developed. Here, we report an enhanced native chemical ligation strategy mediated by peptide conjugation in trifluoroacetic acid (TFA). The conjugation between a carboxyl-terminal peptide thiosalicylaldehyde thioester and a 1,3-dithiol-containing peptide in TFA proceeds rapidly to form a thioacetal-linked intermediate, which is readily converted into the desired native amide bond product through simple postligation treatment. The effectiveness and practicality of the method was demonstrated by the successful synthesis of several challenging proteins, including the SARS-CoV-2 transmembrane Envelope (E) protein and nanobodies. Because of the ability of TFA to dissolve virtually all peptides and prevent the formation of unreactive peptide structures, the method is expected to open new opportunities for synthesizing all families of proteins, particularly those with aggregable or colloidal peptide segments.

Lead-free iron-doped Cs3Bi2Br9 perovskite with tunable properties.

Perovskite based on cesium bismuth bromide offers a compelling, non-toxic alternative to lead-containing counterparts in optoelectronic applications. However, its widespread usage is hindered by its wide bandgap. This study investigates a significant bandgap tunability achieved by introducing Fe doping into the inorganic, lead-free, non-toxic, and stable Cs3Bi2Br9 perovskite at varying concentrations. The materials were synthesized using a facile method, with the aim of tuning the optoelectronic properties of the perovskite materials. Characterization through techniques such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, energy dispersive spectroscopy (EDS), and UV-vis spectroscopy was conducted to elucidate the transformation mechanism of the doping materials. The substitution process results in a significant change in the bandgap energy, transforming from the pristine Cs3Bi2Br9 with a bandgap of 2.54 eV to 1.78 eV upon 70% Fe doping. The addition of 50% Fe in Cs3Bi2Br9 leads to the formation of the orthorhombic structure in Cs2(Bi,Fe)Br5 perovskite, while complete Fe alloying at 100% results in the phase formation of CsFeBr4 perovskite. Our findings on regulation of bandgap energy and crystal structure through B site substitution hold significant promise for applications in optoelectronics.

Crystal-Phase- and B-Content-Dependent Electrochemical Behavior of Pd─B Nanocrystals toward Oxygen Reduction Reaction.

The manipulation of crystal phases in metal-nonmetal interstitial alloy nanostructures has attracted considerable attention due to the formation of unique electronic structures and surface atomic arrangements, resulting in unprecedented catalytic performances. However, achieving simultaneous control over crystal phase and nonmetal elements in metal-nonmetal interstitial alloy nanostructures has remained a formidable challenge. Here, a novel synthesis approach is presented for Pd─B interstitial alloy nanocrystals (NCs) that allows investigation of the crystal-phase- and B-content-dependent catalytic performance. Through comparison of the oxygen reduction reaction (ORR) properties of Pd─BX interstitial alloy NCs with different crystal phases and B contents, achieved by precise control of reaction temperature and time, the influences of crystal phase and B contents in the Pd─BX interstitial alloy NCs on ORR are precisely investigated. The hexagonal closed packed (hcp) PdB0.5 NCs exhibit superior catalytic activity, with mass activities reaching 2.58 A mg-1, surpassing Pd/C by 10.3 times, attributed to synergistic effects by the hcp crystal phase and relatively high B contents. This study not only provides a novel approach to fabricate interstitial alloy nanostructures with unconventional crystal phases and finely controlled nonmetal elements but also elucidates the importance of crystal phase and nonmetal element content in optimizing electrocatalytic efficiency.

Characterization Methods to Determine Interpenetrating Polymer Network (IPN) in Hydrogels.

Significant developments have been achieved with the invention of hydrogels. They are effective in many fields such as wastewater treatment, food, agriculture, pharmaceutical applications, and drug delivery. Although hydrogels have been used successfully in these areas, there is a need to make them better for future applications. Interpenetrating polymer networks (IPNs) can be created to make hydrogels more adjustable and suitable for a specific purpose. IPN formation is an innovative approach for polymeric systems. It brings two or more polymer networks together with entanglements. The properties of IPNs are controlled by its chemistry, crosslinking density, and morphology. Therefore, it is necessary to understand characterization methods in order to detect the formation of IPN structure and to develop the properties of hydrogels. In recent studies, IPN structure in hydrogels has been determined via chemical, physical, and mechanical methods such as Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), and rheology methods. In this paper, these characterization methods will be explained, recent studies will be scrutinized, and the effectiveness of these methods to confirm IPN formation will be evaluated.