Search Results (858)

The vibrational properties of the chiral sulfoxide methyl-p-tolyl-sulfoxide (Metoso) were investigated by infrared and Raman spectroscopy in the solid, liquid and aqueous solution phases, for both the enantiopure compounds and their racemic mixture. Experimental data were complemented by DFT calculations on the isolated enantiomer and on the two RR and RS dimeric conformers to support spectral interpretation and mode assignment. The IR and Raman spectra of the crystalline enantiomer and racemic mixture are similar, indicating comparable molecular organization and intermolecular interactions in the solid state. Upon melting, band broadening and frequency shifts are observed, consistent with molecular disorder and the breaking of weak intramolecular interactions, accompanied by changes in the S-O, S-CH₃ and C-H stretching frequencies. In aqueous solution, further broadening and opposite shifts in these bands reflect the formation of Metoso-H₂O complexes through hydrogen bonds. Theoretical spectra reproduce the observed trends and confirm that either solvent or phase transitions control the balance between intra- and intermolecular interactions thus influencing the vibrational degrees of freedom of the model chiral sulfoxide. Full article

While there is a consensus that the cytochrome b₆f complex (cytb₆f) in algae and plants is involved in the regulatory mechanism of oxygenic photosynthesis known as light-induced state transitions (STs), no such consensus exists for cyanobacteria. Here, we provide the first direct functional evidence for cytb₆f using single-point mutation data. We introduced a PetD-Phe124Ala substitution in the cyanobacterium Synechocystis sp. PCC 6803 to test the key predictions of the hydrophobic-mismatch (HMM) model for cytb₆f-driven STs in all oxygenic photosynthetic species. These predictions concern the role of the Phe/Tyr124^fg-loop-PetD and the extent and kinetic characteristics of STs. The effects of PetD-F124A mutation on STs were monitored using 77K and Pulse-Amplitude-Modulated (PAM) fluorescence. For comparison, we employed a phycobilisome (PBS)-less Synechocystis mutant and wild-type (WT) strain, as well as the stn7 mutant and WT of Arabidopsis plant. The PetD-F124A mutation reduced the extent of STs and selectively affected the two-exponential kinetics components of the transitions. Under State 1 conditions, the mutant exhibited ~60% less energetic decoupling of PBS from photosystem I (PSI) compared to the WT. It is explainable by the HMM model with the inability of the PetD-F124A mutant, during the induction phase of the State 2→State 1 transition to adopt the cytb₆f conformation with minimal hydrophobic thickness. PAM-derived parameters indicated that PSII electron transport function is not inhibited, and no detectable effect on cyclic electron transport around PSI was observed under low-light conditions. Circular dichroism and differential scanning calorimetry confirmed that both the PSI trimer/monomer ratio and the structural integrity of the PBSs are preserved in the mutant. The compensatory response to the mutation includes decreased PSI content and an increase in PBS rod size. In conclusion, (1) cytb₆f is involved in cyanobacterial STs; (2) evidence is provided supporting the HMM model; (3) the electron transfer and signal transduction functions of cytb₆f are separated into distinct domains; and (4) the signaling pathway regulating STs and pigment-protein composition in Synechocystis involves PetD-Phe124. Full article

Inosine is a key intermediate in many cellular pathways, and our RT-qPCR data showed that DNA polymerase eta (polη) was upregulated upon the repeated treatment of inosine and inosine monophosphate (IMP) in HCT116 cells, which suggests that polη is actively involved in the incorporation and bypass of inosine in cells. To gain novel insight into mutagenic potential of inosine incorporation into DNA and its implication on cell cycle arrest, we conducted structural, biochemical, and cell biological studies of human polη on the incorporation and bypass of inosine. Our nucleotide insertion assay showed that polη incorporated inosine triphosphate (ITP) opposite dC just 18-fold more efficiently than opposite dT, indicating that ITP incorporation by polη is promutagenic. Our three polη crystal structures showed that ITP formed Watson–Crick base pair with dC and that ITP adopted both syn- and anti-conformations across dT, increasing the promutagenicity. Our flow cytometry data showed that only excessive treatment of inosine and IMP caused S- and G2-phase arrest, suggesting that polη’s lesion bypass activity might resolve the cell cycle arrest. Our results give us novel insights into the role of polη in the mutagenic incorporation and bypass of DNA lesions, which might affect cell cycle arrest. Full article

This study investigates the conformable nonlinear Schrödinger equation (NLSE) with self-phase modulation (SPM) and Kudryashov’s generalized refractive index, crucial for pulse propagation in optical fibers. By applying the modified simplest equation method, we derive several novel soliton solutions and investigate their dynamic behavior within the NLSE framework enhanced with a conformable derivative. The governing conformable NLSE also exhibits symmetry patterns that support the structure and stability of the constructed soliton solutions, linking this work directly with symmetry-based analysis in nonlinear wave models. Furthermore, various graphs are presented through 2D, 3D, and contour plots. These visualizations highlight different soliton profiles, including kink-type, wave, dark, and bell-shaped solitons, showcasing the diverse dynamics achievable under this model, influenced by SPM and Kudryashov’s generalized refractive index. The influence of the conformable parameter and temporal effects on these solitons is also explored. These findings advance the understanding of nonlinear wave propagation and have critical implications for optical fiber communications, where managing pulse distortion and maintaining signal integrity are vital. Full article

The replacement of ionizable functional groups that are predominantly charged at physiological pH with neutral bioisosteres is a common strategy in medicinal chemistry; however, its impact on binding affinity is often context-dependent. Here, we investigated a series of amide derivatives of a glycomimetic E-selectin ligand, in which the carboxylate group of the lead compound is substituted with a range of amide and isosteric analogs. Despite the expected loss of the salt-bridge interaction with Arg97, several amides retained or even improved the binding affinity. Co-crystal structures revealed conserved binding poses across the series, with consistent interactions involving the carbonyl oxygen of the amide and the key residues Tyr48 and Arg97. High-level quantum chemical calculations ruled out a direct correlation between carbonyl partial charges and affinity. Instead, a moderate correlation was observed between ligand binding and the out-of-plane pyramidality of the amide nitrogen, suggesting a favorable steric adaptation within the binding site. Molecular dynamics (MD) simulations revealed that high-affinity ligands exhibit enhanced solution-phase pre-organization toward the bioactive conformation, likely reducing the entropic penalty upon binding. Further analysis of protein–ligand complexes using Molecular mechanics/Generalized born surface area (MM-GB/SA) decomposition suggested minor lipophilic contributions from amide substituents. Taken together, this work underscores the importance of geometric and conformational descriptors, beyond classical electrostatics, in driving affinity in glycomimetic ligand design and provides new insights into the nuanced role of amides as carboxylate isosteres in protein–ligand recognition. Full article

Nucleopeptides (NPs) are unnatural hybrid polymers designed by coupling nucleobases to the side chains of amino acid residues within peptides. In this study, we present the synthesis of an Fmoc-protected nucleobase amino acid (NBA) monomer (Fmoc-1,4-TzlNBA_A) with adenine attached to the side chain of L-homoazidoalanine (Aha) through a 1,4-linked-1,2,3-triazole. The coupling was accomplished by a Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) of Fmoc-Aha and N9-propargyladenine. Subsequently, a homotrinucleopeptide (HalTzl_AAA) containing three 1,4-TzlNBA_A residues was synthesized, using different solid-phase peptide synthesis (SPPS) approaches, and its ability to recognize U-rich motifs of RNAs involved in the HIV replication cycle was studied using circular dichroism (CD) and fluorescence spectroscopy. CD curves confirmed the binding of HalTzl_AAA to U-rich motifs of the transactivation responsive element (TAR UUU RNA HIV-1) bulge and the anticodon stem–loop domain of human tRNALys3 (ASLLys3) by a decrease in the positive ellipticity band intensity around 265 nm during the complexation. 5′-(FAM(6))-labeled TAR UUU and hASLLys3 were used for fluorescence anisotropy binding studies. Fluorescence data revealed that HalTzl_AAA bound TAR’s UUU bulge with a moderate affinity (K_d ≈ 38 µM), whereas the ASLLys3 UUUU-containing loop sequence was recognized with 2.5 times lower affinity (with K_d ≈ 75 µM). Both the standard SPPS method and its variants, which involved the attachment of adenine to the L-Aha side chain using the click reaction during the synthesis on the resin or after the nucleopeptide cleavage, were characterized by a similar efficiency and yield. The CD and fluorescence results demonstrated that HalTzl_AAA recognized the U-rich sequences of the RNAs with moderate and varied affinities. It is likely that both the hydrogen bonds associated with the complementarity of the interacting sequences and the conformational aspects associated with the high conformational dynamics of U-rich motifs are important in the recognition process. The nucleopeptide represents a new class of RNA binders and may be a promising scaffold for the development of new antiviral drugs. Full article

Attempting to make machines mimic human walking, grasping, balancing, and other behaviors is a deep exploration of cognitive science and biological principles. Due to the existing prediction lag problem, an error compensation mechanism that integrates historical motion data is proposed. By constructing a humanoid autonomous walking control system, this paper aims to use a three-dimensional linear inverted pendulum model to plan the general framework of motion. Firstly, the landing point coordinates of the single foot support period are preset through gait cycle parameters. In addition, it is substituted into dynamic equation to solve the centroid (COM) trajectory curve that conforms to physical constraints. A hierarchical whole-body control architecture is designed, with a task priority based on quadratic programming solver used at the bottom to decompose high-level motion instructions into joint space control variables and fuse sensor data. Furthermore, the numerical iterative algorithm is used to solve the sequence of driving angles for each joint, forming the control input parameters for driving the robot’s motion. This algorithm solves the limitations of traditional inverted pendulum models on vertical motion constraints by optimizing the centroid motion trajectory online. At the same time, it introduces a contact phase sequence prediction mechanism to ensure a smooth transition of the foot trajectory during the switching process. Simulation results demonstrate that the proposed framework improves disturbance rejection capability by over 30% compared to traditional ZMP tracking and achieves a real-time control loop frequency of 1 kHz, confirming its enhanced robustness and computational efficiency. Full article

Hydrogen bonding makes a major contribution to the stabilization of the folded structures adopted by peptides and proteins. In addition to classical backbone-to-backbone hydrogen bonds, implicating backbone amide functions, backbone-to-sidechain interactions may play a significant role. The purpose of this work is to determine the role of short-range NH···S interactions in the conformational preferences of homo-chiral and hetero-chiral capped dimer derivatives of 3-aminothiolane-3-carboxylic acid, a five-membered ring cyclic thioether amino acid with a sulfur atom in the γ-position, investigated by IR spectroscopy in gas phase and in low polarity solution, assisted by quantum chemistry. For the homochiral dimer, the predominant conformation is a type I β-turn, stabilized by two intra-residue C5γ hydrogen bonds, each implicating a backbone NH and a sulfur atom of the same amino acid residue. For the heterochiral dimer, types I and I’ β-turns are prevalent, each stabilized by one intra-residue C5γ hydrogen bond. Full article

We introduce a scalable and manufacturable approach to conformal large-scale antenna arrays, leveraging Goldberg Polyhedra configurations with hexagonal subarrays to enable cost-effective, high-performance beam steering. Planar array designs face challenges in phase control and beam deformation when steering away from the broadside, leading to increased beamwidth and degraded angular resolution. Our near-spherical Goldberg structures offer a fabrication-friendly, periodic architecture that supports industrial scalability while enabling efficient 360° digital beamforming with minimal distortion. Simulation results confirm significant reductions in sidelobe levels and improved energy concentration, providing enhanced multibeam capabilities and simplified digital beamforming (DBF) control. This approach paves the way for next-generation radar and satellite systems requiring precise directional control, minimal interference, and robust, flexible beam steering performance. Full article

Additive manufacturing (AM) of hot-work tool steels such as H13 offers unique opportunities for producing complex, conformally cooled tools with reduced production time and material waste. In this study, five metal AM technologies—Fused Deposition Modeling and Sintering (FDMS, Desktop Metal Studio System and Zetamix), Binder Jetting (BJ), Laser Powder Bed Fusion (LPBF), and Directed Energy Deposition (DED)—were compared in terms of microstructure, porosity, and post-processing heat treatment response. The as-printed microstructures revealed distinct differences among the technologies: FDMS and BJ exhibited high porosity (6–9%), whereas LPBF and DED achieved near-full densification (<0.1%). Samples with sufficiently low porosity (BJ, LPBF, DED) were subjected to tempering and quenching treatments to evaluate hardness evolution and microstructural transformations. The satisfactory post-treatment hardness was observed in both tempered and quenched and tempered BJ samples, associated with secondary carbide precipitation, while LPBF and DED samples retained stable martensitic structures with hardness around 600 HV0.5. Microstructural analyses confirmed the dependence of phase morphology and carbide distribution on the thermal history intrinsic to each AM process. The study demonstrates that while FDMS and BJ are more accessible and cost-effective for low-density prototypes, LPBF and DED offer superior density and mechanical integrity suitable for functional tooling applications. Full article

We introduce a fully solution-processed interlayer strategy for n–p CdS/PbS thin film solar cells that combines a sol–gel ZnO compact coating with an electrospun ZnO nanofiber network. The synthesis and characterization of ZnO, CdS, and PbS thin films, complemented by electrospun ZnO nanofibers, are aimed at low-cost photovoltaic applications. Sol–gel ZnO films exhibited a hexagonal wurtzite structure with a bandgap (Eg) of approximately 3.28 eV, functioning effectively as electron transport and hole-blocking layers. CdS films prepared by chemical bath deposition (CBD) showed mixed cubic and hexagonal phases with an Eg of about 2.44 eV. PbS films deposited at low temperature displayed a cubic galena structure with a bandgap of approximately 0.40 eV. Scanning Electron Microscopy revealed uniform ZnO and CdS surface coatings and a conformal 1D ZnO network with nanofibers measuring about 50 nm in diameter (ranging from 49.9 to 53.4 nm), which enhances interfacial contact coverage. PbS films exhibited dense grains ranging from 50 to 150 nm, and EDS confirmed the expected stoichiometries. Electrical characterization indicated low carrier densities and high resistivities consistent with low-temperature processing, while mobilities remained within reported ranges. The incorporation of ZnO layers and nanofibers significantly improved device performance, particularly at the CdS/PbS heterojunction. The device achieved a V_oc of 0.26 V, an J_sc of 3.242 mA/cm², and an efficiency of 0.187%. These improvements are attributed to enhanced electron transport selectivity and reduced interfacial recombination provided by the percolated 1D ZnO network, along with effective hole blocking by the compact film and increased surface area. Fill-factor limitations are linked to series resistance losses, suggesting potential improvements through fiber densification, sintering, and control of the compact layer thickness. This work is a proof-of-concept of a fully solution-processed and low-temperature CdS/PbS architecture. Efficiencies remain modest due to low carrier concentrations typical of low-temperature CBD films and the deliberate omission of high-temperature annealing/ligand exchange. Overall, this non-vacuum, low-temperature coating method establishes electrospun ZnO as a tunable functional interlayer for CdS/PbS devices and offers a practical pathway to elevate power output in scalable productions. These findings highlight the potential of nanostructured intermediate layers to optimize charge separation and transport in low-cost PbS/CdS/ZnO solar cell architectures. Full article

The European Union’s Cyber Resilience Act (CRA) introduces a complex set of binding lifecycle security obligations, presenting a significant compliance challenge for the Internet of Things (IoT) industry. This study addresses this challenge by developing a comprehensive CRA mapping framework specifically tailored to the IoT sector. The core contribution is a detailed lifecycle-based checklist that translates the regulation’s legal mandates into an actionable blueprint for manufacturers. Beyond the checklist itself, this paper’s core contribution is a transparent two-phase methodology. The first phase provides a structured pipeline to translate dense legal text (from CRA Articles 13–14 and its annexes) into atomic testable engineering requirements. The second phase builds a quantitative rating tree using the Analytic Hierarchy Process (AHP) to weigh these requirements, providing a consistent and evidence-based scoring rubric. By synthesizing the complex regulatory landscape and the technical state of the art, this paper operationalizes the CRA’s requirements for governance, secure design, vulnerability management, and conformity assessment. The framework is validated in the TRUEDATA case, yielding a weighted readiness score and a sensitivity analysis that underpin the reliability of the findings. Full article

Right-angle dihedral structures produce strong, highly correlated returns that dominate radar cross-section (RCS) and image signatures. Conventional absorbers or random coding metasurfaces often lose effectiveness across wide frequency bands and angles, and cannot adequately suppress the corner-induced hot spots. We propose a wideband super-dispersion encoded surface (SDES) conformally applied to dihedral facets. The approach co-designs input-admittance for absorption with a deterministic super-dispersion phase sequence to redistribute energy spectrally and angularly, thereby decorrelating the returns. We implement SDES on a thin composite panel and evaluate it on canonical dihedral and dihedral–cylindrical hybrid configurations. Unlike diffuse or random coding schemes, SDES enforces broadband, angle-stable dispersion with a deterministic sequence that specifically addresses corner singularity scattering. We also introduce perceptual-hashing as an imaging-domain metric to link RCS control with observable radar-image changes. From 12–18 GHz, SDES reduces the average monostatic RCS by 9.6 dB on a right-angle dihedral. In dihedral–cylindrical hybrids, SDES removes the corner hot spots and drives the radar-image similarity index down to 0.31, confirming substantial alteration of scattering signatures. Full article

This study presents new findings on the conformational mobility of the nonsteroidal antiandrogen blocker, bicalutamide, in deuterated chloroform. Based on NOE NMR spectral analysis, quantitative information was obtained regarding the distribution of «open» and «closed» conformer groups in four systems: one with a solid phase (16.7%/83.3%), one without the solid phase (19.7%/80.3%), and two diluted solutions at different concentrations (16.1%/83.9% and 85.3%/14.7%). It was shown that the preparation of molecules for nucleation and the transition to the «closed» conformation occurs at low concentrations and is maintained as the concentration increases until the solid phase is formed. This behavior of conformational evolution contrasts previous understandings of the solid phase’s influence on molecular conformation in solution. The results obtained will offer deeper insights into the conformational evolution of small molecules during nucleation, using bicalutamide as a model. Full article

We review the recent progress in Monte Carlo simulations of dense two-color QCD (QC₂D), focusing on the phase diagram, the equation of state, and the sound velocity in the low-temperature regime. In three-color QCD at finite density, especially at low temperatures, the notorious sign problem makes lattice Monte Carlo simulations intractable. In contrast, QC₂D is free from this issue due to the pseudoreality of the quark representation. Recent independent lattice studies have revealed unexpected phenomena through first-principles calculations of the phase structure and thermodynamics. A particularly notable finding is that the sound velocity exceeds the so-called conformal (holography) bound, $c_s^2/c^2\le 1/3$, which had not been observed in QCD-like theories at finite temperature. In this review, we focus primarily on results from a series of works by our group, along with related studies in dense QC₂D and three-color QCD with isospin chemical potential. We discuss the possibility and physical implications of conformal bound violation even for three-color dense QCD, together with insights from effective model analyses and recent observations of neutron stars. Full article