Structural Characteristics Research Articles

Computational investigation of the structural, mechanical and acoustic characteristics of rare earth based Heusler compounds

The study undertaken on new Heusler compounds to uncover their crystal stability, structural parameters, elastic constants and moduli along with other important related properties. The scheme consisted of PBE-sol potential to treat exchange correlation effects. All the compounds consist of cubic structure where the elastic constants range from 6.57 Å for LuPd2Cd and 6.87 Å for GdAu2Cd. Compounds show high bulk modulus above 80 GPa. The elastic constants calculated were in excellent matching with the any available data while some of the data presented in the study is reported for the first time. Ductile and brittle nature was explored thoroughly for all compounds. Melting temperature, velocity (longitudinal, transverse) of sound, hardness along with other important elastic characteristics were also calculated using different available and established equations. Current work can be very useful to bring forth new results which may help further exploration of these less explored materials.

Structural characteristics of participle forms in the Athonian redaction Gospel of Mark

Structural characteristics of participle forms in the Athonian redaction Gospel of Mark

A Study on the Mast Structure Vibration Limits considering the Operating Time of Naval Ships

The mast structure of a naval ship has a lot of expensive equipment attached and is easily exposed to strong vibration due to its structural characteristics, so it is necessary to manage vibrations well to prevent equipment failure and increase operating time. Since September 2015, the Navy has been managing the vibration of the ship's mast structure with a separate tolerance standard from the local vibration, but this standard is set at 1/2 of the vibration limits for mast-mounted equipment without any engineering basis. So the establishment of new vibration limits based on the operating conditions of naval ships is required. In this study, the mast structure vibration limits were reviewed considering the actual operating time of naval ships, and the results were compared with the standards of major overseas classification societies and the actual measurements of a ship that had mast structure vibration problems.

Statistical analysis of the unique characteristics of secondary structures in proteins

Protein folding is a complex process influenced by the primary sequence of amino acids. Early studies focused on understanding whether the specificity or the conservation of properties of amino acids was crucial for folding into secondary structures such as α-helices, β-sheets, turns, and coils. However, with the advent of artificial intelligence (AI) and machine learning (ML), the emphasis has shifted towards the precise nature and occurrence of specific amino acids. In our study, we analyzed a large set of proteins from diverse organisms to identify unique features of secondary structures, particularly in terms of the distribution of polar, non-polar, and charged amino acid residues. We found that α-helices tend to have a higher proportion of charged and non-polar groups compared to other secondary structures and that the presence of oppositely charged amino acid residues in helices stabilizes them, facilitating the formation of longer helices. These characteristics are distinct to α-helices. This study offers valuable insights for researchers in the field of protein design, enabling the de-novo creation of short helical peptides for a range of applications. We have also developed a web server for extensive analysis of proteins from different databases. The web server is housed at https://proseqanalyser.iitgn.ac.in/

Hydrothermally synthesized binder-less ZnS/CdS on nickel foam as promising hybrid supercapacitor electrode materials

A binary composite of metal sulfides (MS) is directly synthesized on nickel foam through hydrothermal process, resulting in snow like nanosphere suitable for hybrid supercapacitors (HSCs). Herein, a ZnS/CdS binary composite has been grown directly on nickel foam using a simple hydrothermal method. The structural features, morphological characteristics and electrochemical performance of the composite are systematically investigated. Especially, the highest capacitance of 739–325 F/g at 1–10 A/g was attained with good rate performance. Moreover, a binder-less ZnS/CdS/NF composite achieved a high power of 5030 W/kg at 42 Wh/kg energy density by realizing an expanded voltage to 1.8 V with decent durability. Interestingly, a 92.84 % retention was noticed after 6500 cycles, which indicates high performance stability of the ZnS/CdS/NF||AC HSC. These outcomes reveal the promising prospect of all-metal sulfide utilization for next-generation energy storage devices.

The broad-spectrum biocide triclosan trigonal crystal: Experimental and DFT-calculated structural, electronic and optical properties

Triclosan, a member of the broad-spectrum biocide class, has seen widespread usage in various household and healthcare-related products worldwide over the past 35 years. However, its extensive use has raised concerns regarding health and environmental impacts. Notably, there is a notable gap in our understanding of the solid-state properties of triclosan, encompassing both experimental aspects, such as optical absorption, and theoretical insights. Expanding upon the established trigonal crystal structure of triclosan, this study employs experimental techniques including X-ray and photoacoustic-based optical absorption, alongside density functional theory (DFT) calculations, to elucidate its structural, electronic, and optical characteristics. Employing the generalized gradient approximation (GGA) DFT exchange-correlation functional and accounting for dispersion effects, optimal lattice parameters were determined with small deviations from experimental measurements (<∼2.2%). The calculations predict that the triclosan trigonal crystal has very close direct band gaps of about 3.44 eV, almost identical to the value of 3.45 eV derived from photoacoustic optical absorption measurements. Analysis of the calculated optical absorption and complex dielectric function underscores the optical isotropy of solid state triclosan. Furthermore, effective mass computations, in conjunction with the band gap results, suggest that triclosan displays electronic characteristics akin to those of a wide direct gap semiconductor.

A first-principles study of the effects of temperature on the atomic and electronic structures of Mg-montmorillonite with H2O molecule adsorption

The interaction between water and soft rock rich in clay minerals is one of the main factors causing damage in soft rock tunnel engineering. The effects of temperature on the atomic structure and water absorption capacities of clay minerals cannot be ignored. In the present study, the influence of temperature on the microstructure of Mg-montmorillonite and the thermal stability of the Mg-montmorillonite (010) surface were calculated based on density functional theory. Furthermore, the adsorption properties of H2O molecules within different coverages (0 < Θ ≤ 1.0 ML) on the (010) surface were investigated in the temperature range of 0–900 K. First, the volume of Mg-montmorillonite expanded significantly with increasing temperature along the z-axis direction. The surface energy of the Mg-montmorillonite (010) surface decreased with increasing temperature, indicating that the high temperature weakened the interatomic interactions on the surface. Moreover, the calculations demonstrated that H2O molecules could still be stably adsorbed on the Mg-montmorillonite (010) surface at different temperatures, and the order of stable adsorption configurations for a single H2O molecule was hollow > bridge > interlayer bridge > top sites. With increasing coverage of H2O molecules, the adsorption energies increased for the top sites, while decreased for the bridge, hollow, and interlayer bridge sites at high temperature. In addition, the changes in atomic structure and electronic characteristics during water absorption were further explored by calculating the ICOHP, PDOS, and lattice relaxation.

Hamiltonian Properties of Augmented k-Ary n-Cubes with Faulty Edges

The augmented [Formula: see text]-ary [Formula: see text]-cube [Formula: see text] is a recently proposed interconnection network that combines the structural characteristics of [Formula: see text]-ary [Formula: see text]-cube [Formula: see text] and augmented cube [Formula: see text], with better features. In this paper, we investigate the Hamiltonian properties of augmented [Formula: see text]-ary [Formula: see text]-cubes. We prove that the augmented [Formula: see text]-ary [Formula: see text]-cube with any [Formula: see text] (resp. [Formula: see text]) faulty edges admits a fault-free Hamilton cycle (resp. Hamilton path).

Review of the Structural Characteristics and Biological Activities of Tricholoma Secondary Metabolites (2018-2023).

Tricholoma are significant medicinal and edible mushrooms within Basidiomycota. Known for their various medicinal properties such as anti-tumor, immune regulation, and antioxidant effects, they are regarded worldwide as health foods of the 21st century. Tricholoma species produce various types of secondary metabolites, which have been extensively studied by the scientific community. In 2018, Clericuzio et al. summarized the structures, biosynthesis, and biological activities of over one hundred different secondary metabolites isolated from the fruiting bodies of 25 Tricholoma species. Building on this, the present article reviews the research progress on Tricholoma secondary metabolites from 2018 to 2023, identifying a total of 101 compounds, 46 of which were newly discovered. These secondary metabolites include a wide range of chemical categories such as terpenoids, steroids, and alkaloids, demonstrating broad biological activities. This article aims to provide in-depth scientific insights and guidance for researchers in this field by summarizing the chemical and biological properties of these secondary metabolites, promoting further applications and development of Tricholoma fungi in the pharmaceutical and food industries.

Synthesis of UiO-66-NH2@PILs core-shell composites for CO2 conversion into cyclic carbonates via synergistic catalysis under solvent- and additive-free conditions

Metal-organic frameworks (MOFs) have been hybridized with other functional materials, such as ionic liquids, covalent organic frameworks (COFs), and metallic nanoclusters, to fabricate composite materials. These composites possess the structural characteristics of their individual components and exhibit synergistic properties. In this work, we demonstrate the synthesis of core-shell structure UiO-66-NH2@PILs-x composite materials by encapsulating MOFs within ionic polymers (PILs) with varying thicknesses of PILs shell. These hybrid materials serve as bifunctional catalysts for the conversion of CO2 into cyclic carbonates under solvent- and additive-free conditions through a synergistic catalytic effect facilitating the conversion of CO2 into cyclic carbonates under solvent- and additive-free conditions through synergistic catalytic effect, exhibiting superior catalytic performance and excellent recyclability. This MOFs-based composite material provides a competitive approach for CO2 catalytic conversion.

Characteristics of Myocardial Structure and Central Carbon Metabolism during the Early and Compensatory Stages of Cardiac Hypertrophy.

Cardiac hypertrophy is a classical forerunner of heart failure and myocardial structural and metabolic remodeling are closely associated with cardiac hypertrophy. We aim to investigate the characteristics of myocardial structure and central carbon metabolism of cardiac hypertrophy at different stages. Using echocardiography and pathological staining, early and compensatory cardiac hypertrophy were respectively defined as within 7 days and from 7 to 14 days after transverse aortic constriction (TAC) in mice. Among mass-spectrometry-based metabolomics, we identified 45 central carbon metabolites. Differential metabolite analysis showed that six metabolites, including citrate, cis-aconitate and so on, decreased significantly on day 1 after TAC. Ten metabolites, including l-lactate, (S)-2-hydroxyglutarate and so on, were obviously changed on days 10 and 14. Pathway analysis showed that these metabolites were involved in seven metabolic pathways, including carbohydrates, amino acids and so on. Western blot showed the expression of ATP-citrate lyase, malate dehydrogenase 1 and lactate dehydrogenase A in myocardium changed markedly on day 3, while the phosphorylation level of AMP-activated protein kinase did not show significantly difference. We hope our research will promote deeper understanding and early diagnosis of cardiac hypertrophy in clinical practice. All raw data were deposited in MetaboLights (MTBLS10555).

Oligo-Adenine Derived Secondary Nucleic Acid Frameworks: From Structural Characteristics to Applications.

Oligo-adenine (polyA) is primarily known for its critical role in mRNA stability, translational status, and gene regulation. Beyond its biological functions, extensive research has unveiled the diverse applications of polyA. In response to environmental stimuli, single polyA strands undergo distinctive structural transitions into diverse secondary configurations, which are reversible upon the introduction of appropriate counter-triggers. In this review, we systematically summarize recent advances of noncanonical structures derived from polyA, including A-motif duplex, A-cyanuric acid triplex, A-coralyne-A duplex, and T ⋅ A-T triplex. The structural characteristics and mechanisms underlying these conformations under specific external stimuli are addressed, followed by examples of their applications in stimuli-responsive DNA hydrogels, supramolecular fibre assembly, molecular electronics and switches, biosensing and bioengineering, payloads encapsulation and release, and others. A detailed comparison of these polyA-derived noncanonical structures is provided, highlighting their distinctive features. Furthermore, by integrating their stimuli-responsiveness and conformational characteristics, advanced material development, such as pH-cascaded DNA hydrogels and supramolecular fibres exhibiting dynamic structural transitions adapting environmental cues, are introduced. An outlook for future developments is also discussed. These polyA derived, stimuli-responsive, noncanonical structures enrich the arsenal of DNA "toolbox", offering dynamic DNA frameworks for diverse future applications.

Synthesis of porous hypercrosslinked polymers from waste polystyrene for efficient CO2 separation

A series of porous hypercrosslinked polymers (HCP-x) were synthesized from waste polystyrene foam via Fridel-Crafts alkylation reaction, aiming to optimize the utilization of waste plastics. The impact of various crosslinkers on the structural characteristics and CO2 adsorption properties of HCP-x was investigated. The results indicated that HCP-x polymers possess high specific surface areas spanning 830–1182 m2 g−1, abundant narrow micropores, and exceptional thermal stability. Notably, HCP-2 exhibited the highest CO2 adsorption capacity of 2.77 mmol g−1 at 273 K and 1.0 bar. These hypercrosslinked polymers also demonstrated a favorable CO2/N2 ideal selectivity and robust cyclic adsorption performance. Breakthrough experiments confirmed the selective adsorption of CO2 from simulated flue gas containing CO2/N2 (15/85). Additionally, the mechanism underlying CO2 adsorption on HCP-x was elucidated by analyzing adsorption thermodynamics and diffusion kinetics. This study not only introduces an innovative method for recycling waste polystyrene foam but also underscores the potential of HCP-x as an effective adsorbent for CO2 capture.

A study on the sound scattering characteristics in random structure using Voronoi Tessellation

In room acoustic design, the use of acoustic diffusers is an effective method for achieving a uniform sound field and controlling reverberation. A common approach is to use periodic diffusers that control reflection directions based on the wavelength of sound. In this study, we explore the utilization of random and nonperiodic structures as acoustic diffusers, taking inspiration from the amorphous structures in nature. The irregularities in random structures are expected to enable the broad diffusion of a wide range of frequencies in various directions. We utilized Voronoi tessellation in both two and three dimensions to create 2D Voronoi diffusers with irregular aperture shapes and 3D Voronoi diffusers with irregular aperture shapes and slopes. Then, the acoustic diffusion characteristics of the 2D and 3D Voronoi diffusers were compared with a periodic-type structure through the finite element analysis and experiments. On the basis of these results, the irregularities in the openings and slopes of Voronoi diffusers broaden the scattering frequencies and enhance the scattering coefficients. This suggests that amorphous structures utilizing Voronoi tessellation can be effective as acoustic diffusers.

Study on the influence of geometric characteristics of micro-periodic structures with slits on sound absorption properties

In recent years, there has been considerable interest in acoustic metamaterial technology that leverages sub-wavelength scale microperiodic structures to control the behavior of sound waves for sound absorption material development. This technology offers high design flexibility in unit shapes and holds promise for the development of sound absorption materials with diverse characteristics. However, the field remains in its foundational exploration phase, with the detailed relationship between geometric shapes and sound absorption properties yet to be fully elucidated. To address this gap, we conducted a thorough investigation focusing on their relationship by examining the transport parameters of the Johnson-Champoux-Allard-Lafarge-Pride (JCALP) model, which are closely associated with sound absorption properties. We designed a cubic lattice with slits on the incident surface of the unit shape as a microperiodic structure and examined the normal incident sound absorption characteristics using the finite element method. Our results indicate that manipulation of slit partition numbers and slit widths allows for control of transport parameters, suggesting the potential to achieve various sound absorption properties.

Mechanical Characteristics of Deep Excavation Support Structure with Asymmetric Load on Ground Surface

The purpose of this paper is to capture the mechanical response of the support structure of deep excavation subject asymmetric load. A two-dimensional (2D) numerical analysis model was established by taking a pipe gallery deep excavation subject to asymmetric load as an example. The numerical analysis results were in good agreement with the measured data, thus verified the validity of the numerical model. On this basis, the stress and displacement of support structure caused by the change in foundation asymmetric load were studied. According to the numerical results, horizontal displacement of the diaphragm wall (DW) was dominant, and the maximum horizontal displacement of the DW was 7.54 mm when the deep excavation was completed. With the increase in asymmetric load, the left wall displacement continued to increase, while the displacement of the right DW continued to decrease, and the maximum horizontal wall displacement occurred near the excavation face. The DW was the main bending component, and the maximum wall bending moment when the deep excavation was completed was 173.5 kN·m. The maximum wall bending moment increased with the increase in asymmetric load, and the maximum wall bending moment on the left of the deep excavation was greater than that on the right. The inner support sustained the main component of axial force, with the axial force peaking at 1051.8 kN when the deep excavation was completed. The axial force of the inner support increased with increasing the asymmetric load, and the axial force of the second inner support was obviously greater than that of the first inner support. This research has a positive effect on the design and optimization of deep excavation support structure subject to asymmetric load on ground surface.

Identification of ultrasound characteristics in viscoelastic architectured materials by angular measurements in double through-transmission

Recent advances in additive manufacturing of viscoelastic materials have paved the way towards the design of increasingly complex multi-material structures with heterogeneities from the micro- to the macroscale. However, the measurement of ultrasound characteristics in such viscoelastic structures is a challenging problem, due to the strong attenuation related to both the constituent materials and the architecture. We propose here a methodological framework to identify the phase velocity and attenuation in viscoelastic multi-material quasi-heterogeneous samples. The proposed approach relies on measurements achieved in double through-transmission at various incidence angles, referred as theta-scan. The forward modeling of the wave propagation in such media allows then to identify the ultrasound characteristics based on an inverse approach. Experiments were performed on multi-material samples made of a random pattern of inclusions of a soft elastomer inside a rigid glassy polymer. The effects of the volume fraction of the constituent materials on the ultrasound characteristics was evaluated. This methodology open the path towards ultrasonic measurements in highly attenuating architectures

Investigating the structural, electronic, optical and thermodynamic properties of ATiO3 (A = Ba, Ca, Ra) for low-cost energy applications

The structural, optoelectronic, and thermodynamic characteristics of ATiO3 (A = Ba, Ca, Ra) perovskites have comprehensively been investigation first-principles based DFT calculations. The GGA method was employed to handle exchange and correlation potentials. The analysis of the E-V plots indicates that RaTiO3 exhibits the highest level of stability in comparison to BaTiO3 and CaTiO3. The direct band-gap characteristic of the ATiO3 (A = Ba, Ca, Ra) perovskites is apparent in the band structure plots. The band gaps for BaTiO3, CaTiO3, and RaTiO3 are 2.48, 3.15, and 1.91 eV, respectively. The analyzed materials exhibit the highest level of photon absorption in the near UV area, as demonstrated in the ε2(ω) plots. The refractive index n(ω) values reveal that ATiO3 (A = Ba, Ca, Ra) are active optical materials as their n(ω) values are between 1 and 2. These perovskite oxides have optical features that make them promising prospects for anti-reflecting coatings over entire energy span as these materials exhibits a very low reflection (∼20 %) of incident photons. The thermodynamic properties of ATiO3 (A = Ba, Ca, Ra) are assessed to determine their dynamical stability and suitability for thermal applications. The results of the investigation demonstrate that these perovskite oxides have the potential to be used in optoelectronic devices.

Experimental investigation of the sound absorption characteristics of unconsolidated granular materials

In the context of a wider research project investigating the use of Granular Material (GM) within floor and wall structures to increase their sound insulation, this study presents the sound absorption coefficient (SAC) measurements of different thicknesses for a range of GM. A primary aim has been to extend the understanding of the behaviour of GM layers in absorbing the propagated incident sound wave. Equally important has been an assessment of what GM could be sourced from waste and be acceptable for use in buildings from the point of view of fire insulation, handleability, economy, etc. Samples of GM were placed in an 88mm diameter vertical impedance tube and SACs measured up to 2kHz. The results show the effect GM's different structure (size and shape), bulk volume, and mechanical characteristics have on the range and value of the SAC. These determine the extent to which GM could be a replacement for traditional sound absorption materials.

Optimised structural, electronic, optical and mechanical properties of SrTiO3-xHx for photovoltaic applications: a DFT insight

Density Functional Theory (DFT) computations, by CASTEP code with GGA-PBE correlation functional, for SrTiO3-xHx have been carried out to compute elastic, mechanical, structural, electronic, and optical characteristics of SrTiO3-xHx perovskite hydride material at varied levels of replacements (x = 0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8, 2.1, 2.4, 2.7, and 3.0). With the doping of hydrogen, the structure changed from cubic to orthorhombic and then tetragonal. Elastic parameters and negative value of formation energies demonstrate the durability and formability of these materials. It is established that these compounds are brittle by examining the B/G ratio and Poisson ratio. A bandgap is increased from 1.791 eV to 2.441 eV as dopant concentration rises, changing the semiconductor's nature from indirect to direct. Additionally, a detailed explanation of the optical properties for photons in the energy spectrum of 0–10 eV was provided dielectric functions, refractive indices, extinction coefficients, and 0–50 eV were provided including reflectance, absorbance, and energy loss. By increasing hydrogen doping, the highest absorption peak in the visible region is observed for x = 2.1, which shows that SrTiO3-xHx perovskite hydride has revealed stronger potential for photovoltaic applications.