Structural Units Research Articles

Development and structural comparison of alkaline and organosolv coconut husks lignin as an eco-friendly lignin-phenol-glyoxal (LPG) wood adhesives.

The development of eco-friendly wood adhesives have gained more interest among adhesives industries due to the concerns about using carcinogenic formaldehyde and petroleum-based phenol in commercially available adhesives. Therefore, many studies have been done by using lignin to partially replace phenol and completely substitute formaldehyde with non-toxic glyoxal in a wood adhesive formulation. This study focused on using different percentages of lignin substitution (10%, 30% and 50wt%) of alkaline and organosolv coconut husk lignin into soda lignin-phenol-glyoxal (SLPG), Kraft lignin-phenol-glyoxal (KLPG) and organosolv lignin-phenol-glyoxal (OLPG) adhesives. The adhesives were further characterized using various analyses and it showed that 50% lignin substitution was the optimum rate percentage with 50% SLPG adhesive giving the highest solid content, shorter gel time and more viscosity compared to control (PF and PG), KLPG and OLPG adhesives. Mechanical properties revealed that 50% SLPG adhesive showed an improvement performance of tensile strength (TS: 68.98 ± 0.19MPa), internal bonding (IB: 17.01 ± 1.07 Nmm-2), and cross-linking density panels (775.51 ± 8.15kgm-3) due to the higher amount of molecular weight (Mw) as well as higher phenolic-OH that improved the cross-linking reaction between phenol-glyoxal with G-type unit in lignin structure.

Molecular dynamics simulation dataset for xSiO2-yB2O3-(1-x-y)Na2O glasses.

Silicate glasses are commonly used for many important industrial applications. As such, the literature provides a wealth of different structural, physical, thermodynamic and mechanical properties for many different chemical compositions of oxide glasses. However, a frequent limitation to existing datasets is that only one or two material properties can be evaluated for a given sample. Another limitation is that existing experimental datasets do not regularly sample a large section of the phase diagram, which makes the determination of systematic trends difficult. Molecular dynamics (MD) simulations are an excellent tool to gather different structural, physical, thermodynamic and mechanical properties on the same glass sample. Additionally, multiple simulations can be setup to homogeneously sample large sections of the phase diagram. MD simulations were carried out to model glasses of different chemical compositions xSiO2-yB2O3-(1-x-y)Na2O where x and y vary from 0 mol% to 100 mol% in 5 mol% increments and x + y ≥ 50 %. The data presented here includes densities, elementary structural units present in the glass, enthalpies of mixing, elastic moduli, and Poisson's ratio. To estimate the potential-dependent character of the data, two sets of simulations were run in parallel using two different potentials published by Sundararaman et al. and Wang et al. The content of this dataset supports interpretations,discussions, and conclusions in the article entitled "Systematic Approach to Thermophysical and Mechanical Properties of SiO2-B2O3-Na2O Glasses Using Molecular Dynamics Simulations".

Raman and x-ray diffraction data analysis of Ge2Sb2Te5 films using gaussian approximation considering the temperature population factor

The structure particulars of amorphous Ge2Sb2Te5 thermally evaporated on glass substrates, as well as films annealed at temperatures of 500 and 700 K have been studied by the considering of experimentally established facts obtained from X-ray analysis and Raman spectroscopy measurements. The Debye-Scherrer and Williams-Hall methods were applied to the X-ray diffraction data for estimate the size of crystallites, interatomic distances, dislocation density and structure distortion degree. The features of heat treatment effect on numerical values of the above quantities at a given temperatures have been established. The analysis of the spectral distribution of Raman scattering was measured at light frequencies between 40 ÷ 300 cm-1 . The rather extended nature of the identified bands suggests the presence of several vibrational modes, leading to the appearance of individual spectral bands. To determine the vibrational modes, a reduced intensity was constructed from the experimental Raman spectrum data and the Gaussian approximation was applied to the latter. Having a mind the results of published works, the vibration modes existing in the samples obtained immediately after the process of layer application were determined, as well as the chemical nature and structure elements corresponding to these modes forming the amorphous matrix. The vibration modes in crystallized layers after heat treatment at the given temperatures were determined, as well as the chemical bonds and structural units forming their local structure.

Using pretrained graph neural networks with token mixers as geometric featurizers for conformational dynamics.

Identifying informative low-dimensional features that characterize dynamics in molecular simulations remains a challenge, often requiring extensive manual tuning and system-specific knowledge. Here, we introduce geom2vec, in which pretrained graph neural networks (GNNs) are used as universal geometric featurizers. By pretraining equivariant GNNs on a large dataset of molecular conformations with a self-supervised denoising objective, we obtain transferable structural representations that are useful for learning conformational dynamics without further fine-tuning. We show how the learned GNN representations can capture interpretable relationships between structural units (tokens) by combining them with expressive token mixers. Importantly, decoupling training the GNNs from training for downstream tasks enables analysis of larger molecular graphs (that can represent small proteins at all-atom resolution) with limited computational resources. In these ways, geom2vec eliminates the need for manual feature selection and increases the robustness of simulation analyses.

Where Does the Proton Go? Structure and Dynamics of Hydrogen-Bond Switching in Aminophosphine Chalcogenides.

Aminophosphates are the focus of research on prebiotic phosphorylation chemistry. Their bifunctional nature also makes them a powerful class of organocatalysts. However, the structural chemistry and dynamics of proton-binding in phosphorylation and organocatalytic mechanisms are still not fully understood. Aminophosphine chalcogenides, preserving the H2N-P+-Ch- structural motif, represent well-suited molecular models that mimic proton-binding, hydrogen-bond switching and supramolecular self-assembling behavior of catalytically and prebiotically relevant molecules. Through spectroscopic (IR, 1H DOSY, 15N NMR), molecular dynamics, and computational investigations, the dynamic proton switching capability of aminophosphate analogs was demonstrated. It was shown under which conditions the amino (NH2) or chalcogen (Ch) functions in H2N-P+-Ch- structural units are protonated. In fact, all conceivable modes of hydrogen-bonding were identified, revealing substantial differences between the oxygen derivative and the heavier congeners. Using coordinating anions, supramolecular zigzag- and cube-shaped arrangements were found in the solid-state and in solution. After break-up of the cube structure, the sulfides and selenides no longer form stable interactions with HCl molecules. In the absence of coordinating anions, protonation of the chalcogen function is preferred. In contrast to the oxygen derivative, the heavier congeners show dynamic intramolecular proton-hopping between the chalcogen and the amino function.

Where Does the Proton Go? Structure and Dynamics of Hydrogen‐Bond Switching in Aminophosphine Chalcogenides

Aminophosphates are the focus of research on prebiotic phosphorylation chemistry. Their bifunctional nature also makes them a powerful class of organocatalysts. However, the structural chemistry and dynamics of proton‐binding in phosphorylation and organocatalytic mechanisms are still not fully understood. Aminophosphine chalcogenides, preserving the H2N–P+–Ch− structural motif, represent well‐suited molecular models that mimic proton‐binding, hydrogen‐bond switching and supramolecular self‐assembling behavior of catalytically and prebiotically relevant molecules. Through spectroscopic (IR, 1H DOSY, 15N NMR), molecular dynamics, and computational investigations, the dynamic proton switching capability of aminophosphate analogs was demonstrated. It was shown under which conditions the amino (NH2) or chalcogen (Ch) functions in H2N–P+–Ch− structural units are protonated. In fact, all conceivable modes of hydrogen‐bonding were identified, revealing substantial differences between the oxygen derivative and the heavier congeners. Using coordinating anions, supramolecular zigzag‐ and cube‐shaped arrangements were found in the solid‐state and in solution. After break‐up of the cube structure, the sulfides and selenides no longer form stable interactions with HCl molecules. In the absence of coordinating anions, protonation of the chalcogen function is preferred. In contrast to the oxygen derivative, the heavier congeners show dynamic intramolecular proton‐hopping between the chalcogen and the amino function.

Pb4O3I2: A Lead Oxyhalide IR Optical Crystal with an Unprecedented 1∞[O3Pb4] Chain Featuring a Wide Transmittance Range and Large Birefringence.

Among the infrared (IR) optical material systems, the heavy-metal oxyhalide system has become an emerging system in recent years. Introducing heavy-metal cations and halogen anions with large atomic numbers is conducive to widening the IR transparency window and improving the birefringence value. Our experiments focus on the PbO-PbI2 system and find a new lead oxyhalide, Pb4O3I2. The structure of Pb4O3I2 is mainly composed of [OPb4] basic structure units, and triple-row [OPb4] units further connect to form unprecedented 1∞[O3Pb4] infinite chains. Pb4O3I2 exhibits a wide IR transmission range from 0.49 to 15.0 μm, and theoretical calculation shows that Pb4O3I2 has a large birefringence of Δn = 0.098 @1064 nm. The results show that Pb4O3I2 is an example of an IR optical material with good optical properties in heavy-metal oxyhalides, which significantly enriches the diversity of oxyhalides.

Employing Octahedral Net Charge Descriptors for Designing High-Performance Aqueous Proton Batteries.

Recently, aqueous proton batteries have shown promise for electrochemical energy storage using MXene electrodes. However, designing high-performance MXene proton batteries remains challenging due to the inevitable hydrogen evolution reaction (HER), the vast chemical composition space of MXene, and the unclear proton transport mechanism. To tackle these challenges, we established a general descriptor based on structural units of MXenes, termed the octahedral net charge descriptor (Qoct). This descriptor correlates well with HER activity, capacity, and proton transport performance. Based on the descriptor, prediction reveals a dual-proton storage mechanism per site in N-functionalized MXene. Meanwhile, the accuracy of the descriptor is verified across a broader MXene chemical space. Additionally, the kinetic process shows the topological transformation energy barrier of the interfacial solution is profoundly influenced by Qoct, thereby impacting the proton transfer performance. This universal descriptor originates from the different electron filling states on the molecular orbitals of the octahedron. Overall, this work provides an efficient strategy for designing MXene proton batteries and can be extended to other battery and catalysis fields.

Deep proximal gradient network for absorption coefficient recovery in photoacoustic tomography

Objective.The optical absorption properties of biological tissues in photoacoustic (PA) tomography are typically quantified by inverting acoustic measurements. Conventional approaches to solving the inverse problem of forward optical models often involve iterative optimization. However, these methods are hindered by several challenges, including high computational demands, the need for regularization, and sensitivity to both the accuracy of the forward model and the completeness of the measurement data. The aim of this study is to introduce a novel learned iterative method for recovering spatially varying optical absorption coefficients (OACs) from PA pressure measurements.Approach.The study introduces a deep learning-based approach that employs the proximal gradient descent mechanism to achieve optical inversion. The proposed framework consists of multiple cascaded structural units, which iteratively update the absorption coefficients through a learning process, unit by unit.Main results.The proposed method was validated through simulations, phantom experiments, andin vivostudies. Comparative analyses demonstrated that the proposed approach outperforms traditional nonlearning and learning-based methods, achieving at least 12.85% improvement in relative errors, 3.50% improvement in peak signal-to-noise ratios, and 3.53% improvement in structural similarity in reconstructing the OAC distribution.Significance.This method significantly improves the accuracy and efficiency of quantitative PA tomography. By addressing key challenges such as computational demand and sensitivity to the accuracy of the forward model and the completeness of the measurement data, the proposed framework offers a more reliable and efficient alternative to traditional methods, with potential applications in medical imaging and diagnostics.

Employing Octahedral Net Charge Descriptors for Designing High‐Performance Aqueous Proton Batteries

Recently, aqueous proton batteries have shown promise for electrochemical energy storage using MXene electrodes. However, designing high‐performance MXene proton batteries remains challenging due to the inevitable hydrogen evolution reaction (HER), the vast chemical composition space of MXene, and the unclear proton transport mechanism. To tackle these challenges, we established a general descriptor based on structural units of MXenes, termed the octahedral net charge descriptor (Qoct). This descriptor correlates well with HER activity, capacity, and proton transport performance. Based on the descriptor, prediction reveals a dual‐proton storage mechanism per site in N‐functionalized MXene. Meanwhile, the accuracy of the descriptor is verified across a broader MXene chemical space. Additionally, the kinetic process shows the topological transformation energy barrier of the interfacial solution is profoundly influenced by Qoct, thereby impacting the proton transfer performance. This universal descriptor originates from the different electron filling states on the molecular orbitals of the octahedron. Overall, this work provides an efficient strategy for designing MXene proton batteries and can be extended to other battery and catalysis fields.

Differences in Nanoplastic Formation Behavior Between High-Density Polyethylene and Low-Density Polyethylene.

High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) films were used to create nanoplastic (NP) models, with the shape of delamination occurring during degradation. In the case of HDPE, selective degradation occurred not only in the amorphous part, but also in the crystalline part at the same time. Some of the lamellae that extend radially to form the spherulite structure were missing during the 30-day degradation. The length of these defects was less than 1 µm. HDPE disintegrated within units of spherulite structure by conformational defects in lamellae, and the size of the fragments obtained had a wide distribution. LDPE was synthesized by radical polymerization, so it contained a cross-linked part. The part was not sufficiently fused, and when it degraded, it delaminated and separated preferentially. The zeta potential reached a minimum value of approximately -20 mV at the degradation time of 21 days, and then increased. This complex dependence on degradation time was due to NP particle aggregation. The addition of 1% Triton(R) X-114 surfactant was effective in stabilizing the NP dispersion. The particle size remained constant at around 20 nm for degradation times of 15-30 days.

Enhancing Catalytic Removal of Autoexhaust Soot Particles via the Modulation of Interfacial Oxygen Vacancies in Cu/CeO2 Catalysts.

The purification efficiency of autoexhaust carbon strongly depends on the heterogeneous interface structure between active metal and oxide, which can modulate the local electronic structure of defect sites to promote the activation of reactant molecules. Herein, the high-dispersion CuO clusters supported on the well-defined CeO2 nanorods were prepared using the complex deposition slow method. The formation of heteroatomic Cu+-Ov-Ce3+ interfacial structural units as active sites can capture electrons to achieve activation of the NO and O2 molecules. Among all of the synthesized catalysts, the Cu10/CeO2 catalyst exhibits superior catalytic performance (T50 = 351 °C) along with remarkable tolerance to H2O and SO2 in the removal of soot particles. Through a combination of comprehensive characterizations and density functional theory calculations, it is proposed that the interfacial Cu+-Ov-Ce3+ site, acting as an electron enrichment center, can capture electrons from the Cu d-band and Ce d/f-band to obtain high delocalized electron density, and then enhance the oxidation of NO to NO2, which plays a crucial role in the NOx-assisted catalytic mechanism for soot oxidation. This study presents a novel strategy for developing highly efficient catalysts that exhibit resistance to H2O and SO2, aimed at enhancing the removal of soot particles.

Synthesis and Structural Insight into the Bioactivity of Imines with 1,5-Dimethyl-2-Phenyl-1H-Pyrazol-3(2H)-One Structural Unit Derived from Phenolic Aldehydes

Synthesis and Structural Insight into the Bioactivity of Imines with 1,5-Dimethyl-2-Phenyl-1H-Pyrazol-3(2H)-One Structural Unit Derived from Phenolic Aldehydes

Review of long-term performance of timber-concrete composite beams

Timber-concrete composite (TCC) beams are formed by integrating timber beams and concrete slabs into a cohesive structural unit using shear connectors. This integration capitalizes on the tensile strength of timber and the compressive strength of concrete, resulting in excellent load-bearing capacity, bending stiffness, vibration comfort, sound insulation, and fire resistance. The long-term behavior of TCC beams must be emphasized, considering the significant time-dependent behaviors of timber, concrete, and the connection system. This work analyzed the long-term mechanical behavior of TCC beams and systematically reviewed the current research on the long-term performance. The primary focus was on the experimental studies of the shear performance of the shear connectors and the mechanical performance of TCC beams under long-term loads. Furthermore, theoretical methods and numerical simulation analyses for evaluating the long-term performance of TCC beams were analyzed. Strengths and weaknesses of existing theoretical methods are identified, and further research and development in the calculation method of TCC beams under long-term loads is proposed.

A Unified Model of Natural Evolution and the Crises in Particle Physics and Cosmology

A unified model of the evolution of the universe is presented. The model consists of four stages: Planckian, Einsteinian, Darwinian, and Intellectual. The evolution of the universe is described as a single flow of information processing that begins at the Planckian stage and continues into the emergence of the most complex information processor: the human brain and the technologically developed human civilization. Each stage has its own structural and functional unit, carriers of evolutionary information, and driving evolving objects. The Planckian stage is described as a system of quantum-mechanically entangled PlanckITs: an entity that represents existence in a randomized space and randomized time. The space-time continuum is presented as a collection of addressable PlanckYTEs. APlanckYTE contains a fixed number of PlanckITs. In the Einsteinianstage, the leptons and quarks of the latest appeared generation carry the information that define the conditions for the transition to the Darwinian stage. Leptons and quarks code a set of parameters that define the conditions for the origin of life and its subsequent evolution. The following expression: ME = (9ℏc3)/(2αGkTE) is one of the results that supports this fact. The Darwinian stage describes biological evolution. The intellectual stage uses the concepts of life symmetry and intellectual fields to describes the intellectual or cultural evolution of social systems. This paper is the first of three papers: ”A Unified Model of Natural Evolution and the Crises in Particle Physics and Cosmology”; ”Space and Time at Planck’s Scale, Carriers of the Evolutionary Information, and the Evolution of the Universe”; ”Evolutionary Anthropodynamics: The Evolution of Intellectual Systems”. Some calculations are done to support the unified model of natural evolution.

Resveratrol-Based Carbamates as Selective Butyrylcholinesterase Inhibitors: Design, Synthesis, Computational Study and Biometal Complexation Capability.

Considering our previous experience in the design of new cholinesterase inhibitors, especially resveratrol analogs, in this research, the basic stilbene skeleton was used as a structural unit for new carbamates designed as potentially highly selective butyrylcholinesterase (BChE) inhibitors with excellent absorption, distribution, metabolism, excretion and toxicity ADMET properties. The inhibitory activity of newly prepared carbamates 1-13 was tested toward the enzymes acetylcholinesterase (AChE) and BChE. In the tested group of compounds, the leading inhibitors were 1 and 7, which achieved excellent selective inhibitory activity for BChE with IC50 values of 0.12 ± 0.09 μM and 0.38 ± 0.01 μM, respectively. Both were much more active than the standard inhibitor galantamine against BChE. Molecular docking of the most promising inhibitor candidates, compounds 1 and 7, revealed that stabilizing interactions between the active site residues of BChE and the ligands involve π-stacking, alkyl-π interactions, and, when the carbamate orientation allows, H-bond formation. MD analysis confirmed the stability of the obtained complexes. Some bioactive resveratrol-based carbamates displayed complex-forming capabilities with Fe3+ ions as metal centers. Spectrophotometric investigation indicated that they coordinate one or two metal ions, which is in accordance with their chemical structure, offering two binding sites: an amine and a carboxylic group in the carbamate moiety. Based on the obtained in silico, experimental and computational results on biological activity in the present work, new carbamates 1 and 7 represent potential selective BChE inhibitors as new therapeutics for neurological disorders.

Risk Communication and Community Engagement (RCCE) implementations to control cholera outbreak in Oromia region, Ethiopia

BackgroundOromia regional state experiencing cholera outbreaks in a protracted pattern despite various interventions at local and regional levels. This study aimed to examine the implementation of Risk Communication and Community Engagement (RCCE) activities for cholera outbreak control in the region.MethodsWe conducted a quantitative and qualitative mixed-method study. The study included 422 respondents for quantitative, 22 key informant interviews (KII), and 4 Focus Group Discussions (FGDs) for the qualitative methods. Risk Communication and Community Engagement (RCCE) activities were assessed using standard questionnaires adapted from national cholera guideline later categorized as poor, satisfactory and good. The findings have also been derived qualitatively from three distinct themes or pillars, specifically (coordination and logistics, RCCE, and the Oral Cholera Vaccine). The quantitative data were analyzed using Stata, version 14.0, and ATLAS.ti9 software was used for qualitative data analysis. An ordinal logistic regression model was applied to identify factors associated with the RCCE status, and a thematic content analysis was performed for the qualitative study. Odds Ratios with 95% confidence intervals (CI) were used to present the findings from the quantitative analysis.ResultsOnly 53% (223) of participants had received health information on cholera of whom 22.8% (96) had material for Social Behaviour Change (SBC) in the local language (Afan Oromo). The overall RCCE implementation status was rated as poor by 73% of the respondents, satisfactory by 23%, and only 4% rated it as good. Level of education and occupation of the house are among the factors affecting the implementation of RCCE. The qualitative findings revealed a lack of regular community dialogues, and community engagements were notably minimal during the early phase of the outbreak. Overall, the RCCE implementation activities were characterized by inconsistency, a lack of comprehensiveness, and uniformity across all levels.ConclusionThe RCCE-related intervention activities were found to be minimal, inconsistent and less focused. The RCCE interventions and awareness creation need to begin with the small units of the community structures, including individuals and families and have to happen continuously with the community, and health workers' involvement at all level. Preliminary evaluation of Social and Behaviour Change (SBC) materials before their distribution should be made, and adopting diverse communication modalities to control the outbreak.

Unveiling geographical patterns of hierarchy in the Greek labor market network: toward a multilayer “status-polus” model

Abstract This article develops a comprehensive framework for understanding labor markets’ spatial configuration and development dynamics, across multiple spatial scales. It applies to the Greek Labor Market Network and delineates five geographical zones of topological similarity, proposing a “status-polus” model capturing the coexistence between spatial development patterns, structural units, administrative scale, intermodality, and their underlying economic geography theories, by distance. The analysis reveals hierarchical structural variations, a transformation from continuous to point spatial patterns; a reduction and escalation of structural units; a U-shaped rule describing the hubs participation; and the challenges faced by insular regions to integrate this labor market.

Optical parameters and shielding attitude of sodium fluoride in calcium-borate glasses

Borate glasses with compositions xCaO-(30-x)NaF-70B2O3 (x = 0–30 mol%, step 5) were synthesized and characterized to investigate the effects of partially substituting NaF with CaO on radiation shielding ability and optical properties. Density, molar volume, packing density, and free volume were measured and calculated. UV–visible spectroscopy was utilized to determine the optical bandgap and other correlated physical parameters. Moreover, different shielding parameters were evaluated using Phy-X simulation software. From data analyses, it was found that increasing CaO content transformed BO3 to BO4 structural units in the borate glass network, keeping the optical bandgap values between 3.76 and 3.55 eV. In addition, the refractive index varied from 2.32 to 2.4, while molar refractivity and Urbach energy were slightly increased with composition. Moreover, the replacement of NaF by CaO enhanced photon interaction cross-sections, reducing the mean free path and half-value layer. The work demonstrated that controlled additions of an intermediate oxide like CaO can tailor the radiation shielding and optical characteristics of borate glasses for potential applications as transparent radiation shielding materials.

Methodology for managing employee performance in modern commercial organizations.

The purpose of this study is to create a method for managing the productivity of employees of a commercial organization and assess its potential effectiveness through theoretical modeling of the result. The principle of the method is based on the iterative redistribution or reallocation of the employees among the company’s departments or structural units taking into account the current and potential changes in order to increase their labor productivity. Modelling analysis was performed using the retrospective data of the commercial organization — the period under consideration was equal to 39 months. The calculation assessed the dependence of changes on two indicators that noticeably affect the results: the number of cities where the company is present and the number of positions available in the company; it also determined the likely effect of the increase in labour productivity of employees when using the method. The influence of quantity of job positions and cities where company operates on the final result was also determined. The modeling carried out allows to draw a conclusion about the potential effectiveness of this approach, especially for organizations with one or in the same location and/or employing a large number of people performing similar functions, as it does not require significant financial outlays. The content and the results of the work presented in the article will be of interest to both HR practitioners and representatives of the scientific sphere.