Types Of Structures Research Articles

On the glow of cremated remains: long-lived green photo-luminescence of heat-treated human bones.

The long-lived green luminescence of human bone (that has been heated to 600°C for a short duration) is attributed to a carbon quantum dot material (derived from collagen) encapsulated and protected by an inorganic matrix (derived from bone apatite) and is more intense in dense rigid and crystalline parts of (healthy) human bones. The strong collagen-apatite interaction results (upon decomposition) in a protective inorganic environment of the luminescent centers allowing long-lived triplet-based emission of a carbon (quantum) dot-like material at room temperature, as well as resilience against oxidation between 550 and 650°C. The graphitic black phase (obtained upon heating around 400°C) is a precursor to the luminescent carbon-based material, that is strongly interacting with the crystalline inorganic matrix. Human bone samples that have been heated to 600°C were subjected to steady-state and time-resolved spectroscopy. Excitation-emission matrix (EEM) luminescence spectroscopy revealed a broad range of excitation and emission wavelengths, indicating a heterogeneous system with a broad density of emissive states. The effect of low temperature on the heat-treated bone was studied with Cryogenic Steady State Luminescence Spectroscopy. Cooling the bone to 80K leads to a slight increase in total emission intensity as well as an intensity increase towards to red part of the spectrum, incompatible with a defect state model displaying luminescent charge recombination in the inorganic matrix. Time-resolved spectroscopy with an Optical Multichannel Analyzer (OMA) and Time Correlated Single Photon Counting (TCSPC) of these samples showed that the decay could be fitted with a multi-exponential decay model as well as with second-order decay kinetics. Confocal Microscopy revealed distinct (plywood type) structures in the bone and high intensity-fast decay areas as well as a spatially heterogeneous distribution of green and (fewer) red emissive species. The use of the ATTO 565 dye aided in bone-structure visualization by chemical adsorption. Conceptually our data interpretation corresponds to previous reports from the material science field on luminescent powders.

Maximizing flux pinning in YBCO coated conductor films for high-field applications

Our study explores the relationship between BZO nanorod density and magnetic flux pinning in YBCO thin films on coated conductor templates. We identified an optimal BZO doping level of 8%–10%, which maximizes flux pinning and enables the highest critical current densities to be achieved across various temperatures and magnetic field ranges, especially in new types of multilayer structures. Additionally, the formation of a c-axis peak in the angular-dependent critical current curves at high BZO concentrations underscores the significance of collective pinning mechanisms. These results are discussed using a simple pinning model that considers the effects of nanorod spacing and fragmentation. Overall, our findings contribute to the development of high-performance coated conductor layer structures for future power applications, where maximizing flux pinning is essential.

Synthesis and crystal structure of acentric anhydrous beryllium carbonate Be(CO3).

The anhydrous alkaline earth metal carbonate Be(CO3) was synthesized in a laser-heated diamond anvil cell at moderate pressures and temperatures (20(2) GPa and 1500(200) K) by a reaction of BeO with CO2. It crystallizes in the acentric, trigonal space group P3121 with Z = 3. The crystal structure was obtained from synchrotron single crystal X-ray diffraction data and confirmed by density functional theory-based calculations in combination with Raman spectroscopy. Second harmonic generation measurements were employed to verify the acentric space group symmetry. The crystal structure of Be(CO3) is characterized by the presence of isolated [CO3]2--groups and BeO4-tetrahedra. This is a new structure type and such a topology has not been observed in carbonates before. Be(CO3) can be recovered to ambient conditions and is not undergoing a phase transition during decompression.

Multichannel full-space coding metasurface with linearly-circularly-polarized wavefront manipulation

Abstract Achieving independent multitasked wavefront control by using an ultrathin plate is a challenge to increase information capacity in integration optics and radar applications. Transmission-reflection-integrated metasurface provides an efficient recipe primarily for multifunctional meta-device, however it is challenging to synergize both linear polarization (LP) and circular polarization (CP) using a single meta-plate. Here, a multichannel full-space coding metasurface composed of interleaved shared-aperture meta-atom is proposed to achieve large information capacity by capsulating judiciously engineered high efficiency triple sub-elements (modes) in four-layer scheme. By rotating dual-gap split ring resonator and varying size of “L” type structure insulating by a metallic ring with electrostatic-analogue shielding effect, both Pancharatnam–Berry (PB) and dynamic phases are independently realized under CP and LP waves, respectively. Such an extraordinary insulating strategy completely suppresses crosstalk among three modes and unprecedentedly increases the capability in yielding kaleidoscopic wavefront control. To verify the significance, a proof-of-concept metadevice is devised and experimentally demonstrated with tri-channel wavefront manipulations, exhibiting reflective dual-vortex beam and Bessel beam for forward and backward CP wave, respectively at high frequency, while transmissive polarization beam splitting for 45°-LP wave at low frequency. Our finding in polarization-direction multiplexing is expected to generate great interest in electromagnetic integration with emerging degree of freedoms.

Optimum Design of InGaN Blue Laser Diodes with Indium-Tin-Oxide and Dielectric Cladding Layers

The efficiency of current GaN-based blue laser diodes (LDs) is limited by the high resistance of a thick p-AlGaN cladding layer. To reduce the operation voltage of InGaN blue LDs, we investigated optimum LD structures with an indium tin oxide (ITO) partial cladding layer using numerical simulations of LD device characteristics such as laser power, forward voltage, and wall-plug efficiency (WPE). The wall-plug efficiency of the optimized structure with the ITO layer was found to increase by more than 20% relative to the WPE of conventional LD structures. In the optimum design, the thickness of the p-AlGaN layer decreased from 700 to 150 nm, resulting in a significantly reduced operation voltage and, hence, increased WPE. In addition, we have proposed a new type of GaN-based blue LD structure with a dielectric partial cladding layer to further reduce the optical absorption of a lasing mode. The p-cladding layer of the proposed structure consisted of SiO2, ITO, and p-AlGaN layers. In the optimized structure, the total thickness of the ITO and p-AlGaN layers was less than 100 nm, leading to significantly improved slope efficiency and operation voltage. The WPE of the optimized structure was increased relatively by 25% compared to the WPE of conventional GaN-based LD structures with a p-AlGaN cladding layer. The investigated LD structures employing the ITO and SiO2 cladding layers are expected to significantly enhance the WPE of high-power GaN-based blue LDs.

Comparisons of acoustic structures between sexes in a duetting, montane bird

Female song in birds is more widespread than previously thought, and studies across different species are critical for better understanding the entire evolutionary process of bird song. In this study, we recorded the songs of males and females in a duetting, montane bird species, the Elliot's laughingthrush Trochalopteron elliotii, across consecutive breeding seasons. We specifically focused on identifying the number and structure of different song types by males and females, and compared these acoustic structures between the sexes. Our findings revealed that both males and females sang sex‐specific solos. More specifically, females sang a single type of solo that varied significantly in the number of notes, whereas males produced three different solos composed of 2, 3, or 4 notes, respectively. Female solos exhibited significantly more notes and longer song duration compared to males. Male solos typically had a significantly higher maximum frequency for the entire song. No significant differences were observed in the duration of the first note, song rate, and other frequency characteristics between male and female solos. Furthermore, paired males and females coordinated their sex‐specific solos to form duets when challenged by conspecific territory intruders, both within and outside the breeding season. Sex‐specific solos suggested that male and female songs play different roles and may be subject to different selective pressures. Further research is necessary for elucidating the functions of male song, female song, and duets in this montane bird species.

Effect of Sourdough–Yeast Co-Fermentation on Physicochemical Properties of Corn Fagao Batter

Fagao is one of China’s traditional gluten-free staple foods made with rice or corn flour. Corn Fagao prepared by co-fermentation with sourdough and yeast exhibits better quality and less staling compared to traditional yeast-fermented Fagao. The physicochemical properties of corn Fagao batter during sourdough–yeast co-fermentation were investigated. The results showed that compared with yeast fermentation, the gas production and viscosity of the batter increased with co-fermentation. The co-fermented batter showed a higher hydrolysis of starch and less amylose content. The integrity of starch granules in the co-fermented batter was damaged more seriously, and the crystallinity and short-range ordered structure were less than in the yeast-fermented batter, even though the crystal structure type of starch did not obviously change. The peak viscosity, minimum viscosity, final viscosity, decay value, and recovery value of the corn batter were reduced by co-fermentation, which improved the thermal stability of the batter and slowed down the aging. Co-fermentation also resulted in a more pronounced reduction in protein subunit content than yeast fermentation. The changes in the physicochemical properties of the corn Fagao batter help explain the improvement in quality of corn Fagao made from the co-fermentation method and may provide theoretical references for co-fermentation with sourdough and yeast to other gluten-free foods.

Synthesis of mixed-base active material from drilling fluid solid waste and biomass for oil wastewater adsorption and its mechanism

To address the issues of high energy consumption, high cost and the risk of secondary pollution in drilling fluid solid waste treatment methods, this study prepared a mixed-based active material using drilling fluid solid waste and biomass materials as raw materials. The mixed-based active material is characterized by its abundant pore structure and high pore volume, demonstrating excellent adsorption performance for heavy metal ions and residual oil in industrial wastewater. Thermogravimetric and basic physical property analyses indicated a synergistic effect between drilling fluid solid waste and biomass materials, showing that joint pyrolysis of the two can enhance the yield of active materials. The adsorption performance of mixed-base active materials for heavy metal ions and residual oil were was tested. It was found that the removal rate of four heavy metal ions (Cr6+, Mn2+, Cu2+, and Zn2+) from the solution could reached 57.1 %, 96.3 %, 99.0 % and 94.1 %, respectively, at a concentration of 0.5 g/L of mixed-base active materials. Characterization revealed that the mixed-base activated carbon has a well-developed pore structure and numerous types of functional groups. The isothermal adsorption process of heavy metal ions by the active material is consistent with the Langmuir model and belongs to the monomolecular layer adsorption. The adsorption rate model of residual oil in wastewater by active materials conforms to the pseudo-second-order equation. The adsorption performance of mixed-base active materials primarily stems from physical adsorption enabled by their well-developed internal pore structure, along with chemical adsorption facilitated by oxygen- and nitrogen-containing functional groups on the surface.

Effect of fiber content on flexural properties of jute fiber reinforced perlite/gypsum composite core-based sandwich structures

In this work, two types of sandwich structures were fabricated to develop sustainable building materials using renewable and waste resources. The chopped jute fiber reinforced perlite-filled gypsum composite was used as the core and the brown paper and the woven jute fiber reinforced epoxy composite (JFRC) were used as skins to manufacture the sandwiches. The effect of jute fiber content (10 g - 20 g) in the core on the flexural properties was studied. The flexural test was conducted to determine the flexural strength, modulus, energy absorption, and the load-bearing capacity of brown paper skin-based sandwiches (BPSS) and JFRC skin-based sandwiches (JFSS). The results of this study show that the flexural properties of both BPSSs and JFSSs are improved significantly with increasing jute fiber content up to 17.5 g indicating the optimum fiber content. The flexural strength and modulus of BPSS at 17.5 g jute fiber content are respectively 8.44 % and 30.16 % greater than those at 10 g jute fiber content. On the other hand, the JFSSs show 30.24 % and 60.36 % increase in flexural strength and modulus respectively at 17.5 g jute fiber content compared to those at 10 g fiber content. The flexural energy absorptions of BPSS and JFSS are also increased by 45.40 % and 22.90 % respectively when jute fiber content in the core is increased from 10 g to 17.5 g. The specific load-bearing capacity of JFSSs is 130.38 % - 216.56 % greater than BPSSs depending on the fiber content in the core.

The structural mechanisms of pressure-induced phase transitions in the Carpy-Galy phase layered perovskites

In layered perovskites with the Carpy-Galy structural type, similar structural phase transitions occur under high pressure. These structural changes, which are crucial for the pressure-induced phase transition in layered perovskite, were analyzed based on experimental X-ray diffraction data. The tilting of the Ti-O6 octahedra and the distortion of the arrangement of rare-earth atoms were studied in detail. Changes in these structural features in layered perovskite serve as common indicators of the phase transition to the monoclinic phase that occurs under high pressure application.

Mechanism of eccentricity influence on 3-DOF aerodynamic stability: New insights into instability evolution, energy harvesting, and vibration control

The inconsistency of mass center and elastic center, i.e., eccentricity, widely exists in various engineering structures and components, including iced conductors, wind turbine blades, airfoils, and cable-supported bridges, and can also be extended to the application of energy harvesting and vibration control. Although the eccentricity influence on aerodynamic stability has already been recognized as important, the underlying mechanism remains rather unclear. This study established a comprehensive framework of explicit eigenvalue solutions, offering in-depth insights into the aerodynamic stability mechanism in a vertical-horizontal-torsional 3-degree-of-freedom linear system under all possible frequency scenarios. These solutions elucidated the coupling mechanism of eccentricity, aerodynamic damping, aerodynamic stiffness, and structural frequencies. Remarkably straightforward criteria to predict the promoting/suppressing effect of eccentricity were proposed, consisting of eccentric angle and aerodynamic forces, which not only align with the traditional principles but also offer a broader application range in terms of structure types and wind speeds. Validations of the proposed solutions were performed for all frequency cases via numerical studies. For instability tendency evaluation, numerical studies on a thin plate showed that eccentricity has a significant impact due to the strong aerodynamic effect and large ratio of width/gyration radius, highlighting the importance of considering small eccentricity errors during experiments. Examination for energy harvesting revealed that a small eccentricity can dramatically enhance power generation efficiency, and the explicit solutions successfully explained the rules governing performance changes against frequency ratio, mass center position, rotation center position, etc. The analysis of a bundled conductor showed that the double pendulum can control galloping because it diminishes the eccentricity effect by shifting the eccentric angle. The proposed explicit solution framework provides a systematic view and new insights into the aerodynamic instability mechanism influenced by eccentricity, serving as a reference for the design and studies of various engineering structures, energy harvesting, and vibration control.

Enhanced magnetic refrigeration capacities of Er6FeSb2 by manganese substitution

Er6FeSb2 is a potential magnetic refrigeration material that can work at the liquid hydrogen temperature range. This work enhances the magnetic refrigeration performance of Er6Fe1-xMnxSb2 by Mn substitution. Mn doping increases the cell volume while maintaining the compound’s crystal structure type. It also results in an increase in the charge density distribution between Er1 and Fe/Mn. As the Mn content increases, the ferromagnetic exchange is enhanced, and the TC continuously increases. The Mn doping induces spin reorientation at low temperature, transforming compounds from traditional magnetocaloric effects to table-like magnetocaloric effects, greatly enlarge the cooling temperature range. When the content of Mn increases from x = 0 to x = 0.3, the δTFWHM increases from 26 K to 62 K, the −(ΔSM)max decreases from 12.1 J/(kg·K) to 5.9 J/(kg·K), and the RCP first increases and then decreases, reaching the maximum value of 435.0 J/kg at x = 0.2. This study opens a new path for the search of magnetic refrigeration material with large cooling temperature range.

Formation mechanism and evolution of flow patterns for thermal convection in an inner cylinder-heated annular pool

In this paper, a set of numerical simulations were carried out to analyze the evolution and formation mechanism of various flow patterns for thermal convection in inner cylinder-heated annular pools at different depths. The results show that the basic flow bifurcates into the second type of hydrothermal waves, standing waves, petal-like structures, and spoke patterns after the flow destabilization. The formation mechanisms of these four flow patterns are all due to the lag in phase between temperature and velocity fluctuations. The reduction in surface azimuthal temperature fluctuation causes the second type of hydrothermal waves to bifurcate into standing waves. The bifurcation from standing waves to petal-like structures is due to the amplitude of azimuthal velocity fluctuation on the free surface being one order of magnitude smaller than that of radial velocity fluctuation. The bifurcation from petal-like structures to spoke patterns is because basic flow varies as the depth rises. Unlike the second type of hydrothermal waves, for standing waves, petal-like structures, and spoke patterns, the temperature fluctuation on different horizontal planes is different. Besides, for standing waves, the periodical variation process of the flow field depends on the azimuthal position.

Optimization of tuned mass dampers – minimization of potential energy of elastic deformation

A tuned mass damper (TMD) optimization can be performed under various assumptions and objectives. All the variables of the optimization, such as structural model, performance index and load type affect the optimal parameters of the TMD. This paper presents a new optimization method that implements straightforward performance index and allows taking load spectral characteristics into account. Thanks to the usage of modal coordinates, the method allows fast numerical optimization of TMD attached to large or complicated structures with numerous degrees of freedom. One of the complicated tasks while optimizing TMD is the choice of a performance index. In this paper, the mean value of potential energy stored in the elastic deformation of a structure under periodic load serves as a performance index, which leads to a low numerical complexity task if the optimization is performed in the frequency domain. The new method also allows a simple inclusion of load spectral characteristics and permits TMD optimization for any loading spectral range. When applied to a structure with a single degree of freedom, this method leads to H2 optimization in the case of white noise excitation. However, it is applicable to multiple degrees of freedom structures with single or multiple TMDs and any given load. The paper also presents several examples of numerical optimization of the TMD attached to both single and multiple degrees of freedom structures under various loads, including white noise excitation, pedestrian load, and earthquake strong motion.

Sr 4 Os 3 O 12 — A Layered Osmate(V,VI) that is Magnetic close to Room Temperature

A novel mixed‐valence osmate(V,VI) Sr 4 Os 3 O 12 is reported, which is attracted to a permanent magnet at room temperature (290 ± 5 K) but loses this property when heated or cooled. In this temperature interval, soft magnetic behavior but the saturation magnetization is only 0.05 μ B per formula unit. The compound crystallizes in the La 4 Ti 3 O 12 structure type. The structure is a rhombohedral stack of layered blocks, each of which can be considered as a section of three layers of the cubic perovskite structure cut perpendicular to one of its threefold axes. The Os–O–Os bond angle of about 175° favors superexchange that leads to antiferromagnetic coupling between the osmium atoms with 5 d 3 and 5 d 2 configurations. Sr 4 Os 3 O 12 exhibits strong lattice dynamics. One aspect is the antiferro‐rotative lattice modes of the corner‐sharing [OsO 6 ] octahedra, which freeze upon cooling. At 100 K, an ordered, yet twinned triclinic superstructure is formed. Strong spin‐orbit coupling and other effects cause deformations of the [OsO 6 ] octahedra that differ significantly at 300 K and 100 K, suggesting a change in the electronic configuration.

P-type nickel cobalt oxide synthetized by chemical bath deposition to applications on thin film transistors

This work studies nickel-cobalt oxide (NiCo2O4) thin films synthesized via chemical bath deposition for potential application as p-type active layers in electronic devices. X-ray photoemission electron spectroscopy (XPS) confirms the synthesis of a ternary compound with a stoichiometry of Ni1.04Co1.96O4. The thin film sample exhibiting the closest stoichiometry to the ternary compound has a thickness of approximately 50 nm. Scanning Electron Microscopy (SEM) micrographs indicate an increase in surface porous size corresponding to higher nickel concentrations in the ternary compound. All synthesized NiCo2O4 thin films demonstrate p-type behavior. The lowest resistivity film had a majority carrier concentration of 1×1020 1/cm3, a mobility value of 0.1 cm2/V·s, and a resistivity of 0.1 Ω cm. X-ray diffraction (XRD) studies reveal that the thin films have a type of spinel cubic structure for the phase NiCo2O4. Characteristic spinel bands are observed in the UV–Vis transmittance spectra, and the energy bandgaps of the Ni1.04Co1.96O4 film are estimated to be approximately 3.41 and 2.19 eV using the Tauc method. The thin film with the lowest resistivity was used as an active layer to fabricate a thin-film transistor, displaying typical output curves of a p-channel transistor.

Multi-target anti-diabetic styrylpyrones from Phellinus igniarius: Inhibition of α-glucosidase, protein glycation, and oxidative stress

Bioactivity screening revealed that the EtOAc extract from the culture broth of Phellinus igniarius SY489 exhibited remarkable α-glucosidase inhibitory activity, with an IC50 value of 1.92 μg/mL. Activity- and ultraviolet (UV) profile-guided isolation led to the discovery of four anti-diabetic styrylpyrones (1–4), including two novel compounds, phelignidins A (1) and B (2). Compounds 1 and 2 represent a rare structural type of styrylpyrone dimer, in which one of the pyrone moieties exists in an open-ring state. The absolute configurations of the new compounds 1 and 2, as well as the previously unresolved compound 3, were established. Compounds 1–4 were effective in α-glucosidase inhibition, anti-glycation, and antioxidant assays, surpassing or being comparable to the positive control drugs, with minimal cytotoxicity. Furthermore, studies on α-glucosidase inhibition mechanisms suggested that these compounds interact with α-glucosidase at a single binding site, causing secondary structure unfolding and exerting inhibitory activity via a mixed-type mechanism. These results provide an important basis for developing novel, low-toxicity, multi-target anti-diabetic drugs from edible and medicinal fungi.

Sound transmission loss and bending properties of sandwich structures based on triply periodic minimal surfaces

Four types of triply periodic minimal surfaces sandwich structures (TPMS-SS), namely, G-SS, D-SS, D1-SS, and IWP-SS, have been proposed. The bending properties were evaluated by experiments and numerical simulations, and their sound insulation performance was investigated using theoretical, numerical and experimental methods. Firstly, the bending performance of four TPMS-SS was compared. Then, the acoustic vibration control equation of TPMS-SS was established and the theoretical solution for the sound transmission loss (STL) was derived based on Reissner's theory combined with the fluid-solid coupling condition. Next, experimental study was conducted on the STL performance of TPMS-SS using the impedance tube method, and the numerical model was verified using theoretical and experimental results. Finally, parametric studies were carried out to investigate the effects of parameters such as relative density (RD), panel thickness (hf), and sound incidence elevation angle (φ), as well as the type of structure, on the STL performance. The results show that TPMS-SSs can achieve >30 dB of STL in the frequency range of 1 Hz to 10 kHz. The STL value increases with relative density (RD), panel thickness (hf), and sound incident elevation angle (φ), while the location of the dips in the STL curves is affected by relative density and panel thickness. G-SS has the best bending performance, while D1-SS has the best acoustic performance. The results could be used for the optimization design of lightweight sandwich structures.

Simplified approach to estimating the loading response of traffic infrastructures

Various numerical methods are commonly used to model the loading response of traffic infrastructures. However, the broader implementation of these methods into practice is typically limited by the high computing cost or technical complexity of the models. Computationally lighter methods are especially needed when a substantial number of calculations must be performed. Hence, this paper introduces a new simplified approach to estimating the loading response of different traffic infrastructures, e.g. roads and railways. This approach is based on the novel approximate solution for the vertical and shear stress fields caused by a uniformly distributed circular surface load. The presented theory has been validated using versatile field measurement data from different types of road structures under varied loading conditions. In the verification calculations, both the vertical stresses within the structure and the deflection of the road surface were examined. The findings indicate that the model closely aligns with the behavior observed in actual structures. The approach presented in this paper enables a quick and easy determination of the loading response of multi-layer traffic infrastructures, providing a new practical calculation tool for researchers and practitioners.

Seismic Performance of Industrial Buildings During the 2023 Kahramanmaras, Turkey Earthquakes

ABSTRACT This study investigates the structural performance of industrial buildings following the February 6, 2023, earthquakes in Kahramanmaras, Turkey, focusing mainly on industrial zones. Causes of damage and damage levels were evaluated for 389 industrial structures, including precast concrete and steel structures. This research demonstrates the need for improved construction practices, advanced seismic design, and quality control. Commonly observed structural damage is highlighted. Identifying the critical common structural damage types is essential to developing effective mitigation strategies and enhancing earthquake resilience. It is concluded that advanced seismic design practices can significantly improve the overall structural performance, resilience, and functional recovery.