Search Results (1,076)

The paper examines the impact of passive restraint on fire-induced spalling in concrete, utilizing a concrete mixture to minimize compositional variability. A variety of specimen geometries was prepared, including standard cubes and cylinders for the determination of mechanical properties and slabs of different dimensions for fire spalling tests conducted under controlled conditions. A top-opening Dragon furnace, which applies ISO 834-1 fire curves, was used to evaluate the influence of “cold rim” boundaries, where slab edges were insulated to create thermal restraint. The cold rims were categorized as 0 cm, 10 cm, and 20 cm, with each modification representing a different degree of thermal expansion restraint. Digital image correlation (DIC) was utilized to monitor the strain fields on the unheated slab surfaces. The findings demonstrated that increasing the cold rim width implies a rise in compressive stress and strain in the central zone, thereby precipitating a more pronounced spalling behaviour. The unrestrained slabs (cold rim 0 cm) exhibited minimal spalling, whereas the restrained slabs (cold rim 20 cm) demonstrated significant spalling depths and volumes. The study confirms that thermal dilation restraint intensifies the severity of spalling and provides a quantitative framework that links stress evolution, strain distribution, and spalling depth. The findings emphasize the necessity of managing thermal restraint to properly assess fire-induced concrete spalling in material screening tests. Full article

In this article, we investigate the encapsulation of K₂[Ni(maleonitriledithiolate)₂] (1) within a host molecule, β-cyclodextrin (β-CD), via single-crystal X-ray analysis. An inclusion complex, K₂{[Ni(maleonitriledithiolate)₂]@(β-CD)₂} (2), was constructed from 1 and two β-CDs. The anion guest Ni complex included a host cavity, constructed using two β-CDs, and the Ni atom of the anion was located between the two hydrophilic primary rims. Ultraviolet-visible absorption spectroscopy revealed that inclusion complex 2 exhibited a 2:1 (host:guest) stoichiometry in the solution, which is consistent with the result obtained from X-ray crystallography. The association of the host and guest occurred in two steps, and the association constants for the first and second steps were 1.1(7) × 10⁴ and 1.8(5) × 10⁴ mol⁻¹ dm³, respectively. The catalytic behavior of 1 and 2 was investigated for electrochemical hydrogen production in the aqueous solution of an acetate buffer (pH = 4.72). During the catalytic reaction, inclusion complex 2 was observed to have a better catalytic reaction rate than 1. The study findings provide insights into the effects of the encapsulation of guest molecules within host structures. Full article

As a range-free localization algorithm, DV-Hop has gained widespread attention due to its advantages of simplicity and ease of implementation. However, this algorithm also has some defects, such as poor localization accuracy and vulnerability to network topology. This paper presents a comprehensive analysis of the factors contributing to the inaccuracy of the DV-Hop algorithm. An improved proportional integral derivative (PID) search algorithm (PSA) DV-Hop hybrid localization algorithm based on weighted hyperbola (IPSA-DV-Hop) is proposed. Firstly, the first hop distance refinement is employed to rectify the received signal strength indicator (RSSI). In order to replace the original least squares solution, a weighted hyperbolic algorithm based on the degree of covariance is adopted. Secondly, the localization error is further reduced by employing the improved PSA. In addition, the selection process of the node set is optimized using progressive sample consensus (PROSAC) followed by a 3D hyperbolic algorithm based on coplanarity. This approach effectively reduces the computational error associated with the hopping distance of the beacon nodes in the 3D scenarios. Finally, the simulation experiments demonstrate that the proposed algorithm can markedly enhance the localization precision in both isotropic and anisotropic networks and reduce the localization error by a minimum of 30% in comparison to the classical DV-Hop. Additionally, it also exhibits stability under the influence of a radio irregular model (RIM). Full article

Hydroxypropyl-β-cyclodextrin (HPβCD) is a derivatized cyclodextrin in which several H atoms on the hydroxyls of the glucose rings are substituted by 2-hydroxypropyl groups. The cyclic structure of HPβCD creates a cavity capable of totally or partially enclosing different molecules (inclusion complexes), and this capacity makes it useful in the pharmaceutical industry. Rifampicin is an antibiotic commonly used to treat tuberculosis; however, some of its properties such as its low solubility and variable bioavailability need to be improved by encapsulating it in systems such as HPβCD. The inclusion complexes formed by twelve structures of HPβCD and rifampicin with various polar and non-polar solvents are studied using molecular simulation. Diverse solvents are simulated using the zwitterionic or neutral configuration of rifampicin, and different values of relative permittivity in the electrostatic contribution to the total energy. The latter constant has little effect on the formation of inclusion complexes, whereas the type of rifampicin essentially determines the energies and configurations of the complexes. The zwitterion is located near the primary rim of HPβCD and the neutral form of rifampicin is near the secondary one. In both cases, the piperazine tail is incorporated into higher-energy complexes inside the host. Full article

Applying an extended Peierls–Hubbard model to $\pi$ electrons in a coronene isomer, we investigate their ground-state properties and photoinduced dynamics with particular interest in possible loop current states. Once we switch on a static magnetic field perpendicular to the coronene disk, diamagnetic (diatropic) and paramagnetic (paratropic) loop currents appear on the rim circuit and inner hub, respectively. Besides this well-known homocentric two-loop current state, heterocentric multiloop current states can be stabilized by virtue of possible electron–lattice coupling. These multiloop current states generally have a larger diamagnetic moment than the conventional two-loop one, and hence it follows that coronene, or possibly polycyclic conjugated hydrocarbons in general, may become more aromatic than otherwise with their $\pi$ electrons being coupled to phonons. When we photoirradiate a ground-state coronene isomer without applying a static magnetic field, loop currents are induced in keeping with the incident light polarization. Linearly and circularly polarized lights induce heterocentric two-loop and multiloop currents, respectively, without and together with two homocentric loop currents of the conventional type, respectively. The heterocentric two-loop currents occur in a mirror-symmetric manner, which reads as the emergence of a pair of antiparallel magnetic moments, whereas the heterocentric multiloop ones appear at random in both space and time, which reads as the emergence of disordered local magnetic moments. Full article

The drive system of an electric car must meet road requirements related to overcoming obstacles and driving dynamics depending on the class and purpose of the vehicle. The driving dynamics of modern cars as well as size and weight limitations mean that wheel hub motors operate with relatively high current density and high power supply frequency, which may generate significant power losses in the windings and permanent magnets and increase their operating temperature. Designers of this type of motor often face the need to minimize the motor’s weight, as it constitutes the unsprung mass of the vehicle. Another limitation for motor designers is the motor dimensions, which are limited by the dimensions of the rim, the arrangement of suspension elements and the braking system. The article presents two directions in the design of wheel hub motors. The first one involves minimizing the length of the stator magnetic core, which allows for shortening of the axial dimension and mass of the motor but involves increasing the thermal load and the need for deeper de-excitation. The second one involves increasing the number of pairs of magnetic poles, which reduces the mass, increases the internal diameter of the motor and shortens the construction of the fronts, but is associated with an increase in the motor operating frequency and increased power losses. Additionally, increasing the number of pairs of magnetic poles is often associated with reducing the number of slots per pole and the phase for technological reasons, which in turn leads to a greater share of spatial harmonics of the magnetomotive force in the air gap and may lead to the generation of higher power losses and higher operating temperatures of permanent magnets. The analysis is based on a simulation of the motor operation, modeled on the basis of laboratory tests of the prototype, while the car is driving in various driving cycles. Full article

New data, including Raman spectroscopy, characterize unusual mineral assemblages from rocks of the Naylga and Khamaryn–Khyral–Khiid combustion metamorphic complexes in Mongolia. Several samples of melilite–nepheline paralava and other thermally altered (metamorphosed) sedimentary rocks contain troilite (FeS), metallic iron Fe⁰, kamacite α-(Fe,Ni) or Ni-bearing Fe⁰, taenite γ-(Fe,Ni) or Ni-rich Fe⁰, barringerite or allabogdanite Fe₂P, schreibersite Fe₃P, steadite Fe₄P = eutectic α-Fe + Fe₃P, wüstite FeO, and cohenite Fe₃C. The paralava matrix includes a fragment composed of magnesiowüstite–ferropericlase (FeO–MgO solid solution), as well as of spinel (Mg,Fe)Al₂O₄ and forsterite. The highest-temperature mineral assemblage belongs to a xenolithic remnant, possibly Fe-rich sinter, which is molten ash left after underground combustion of coal seams. The crystallization temperatures of the observed iron phases were estimated using phase diagrams for the respective systems: Fe–S for iron sulfides and Fe–P ± C for iron phosphides. Iron monosulfides (high-temperature pyrrhotite) with inclusions of Fe⁰ underwent solid-state conversion into troilite at 140 °C. Iron phosphides in inclusions from the early growth zone of anorthite–bytownite in melilite–nepheline paralava crystallized from <1370 to 1165 °C (Fe₂P), 1165–1048 °C (Fe₃P), and <1048 °C (Fe₄P). Phase relations in zoned spherules consisting of troilite +Fe⁰ (or kamacite + taenite) +Fe₃P ± (Fe₃C, Fe₄P) reveal the potential presence of a homogeneous Fe–S–P–C melt at T~1350 °C, which separated into two immiscible melts in the 1350–1250 °C range; namely, a dense Fe–P–C melt in the core and a less dense Fe–S melt in the rim. The melts evolved in accordance with cooling paths in the Fe–S and Fe–P–C phase diagrams. Cohenite and schreibersite in the spherules crystallized between 988 °C and 959 °C. The crystallization temperatures of minerals were used to reconstruct redox patterns with respect to the CCO, IW, IM, and MW buffer equilibria during melting of marly limestone and subsequent crystallization and cooling of melilite–nepheline paralava melts. The origin of the studied CM rocks was explained in a model implying thermal alteration of low-permeable overburden domains in reducing conditions during wild subsurface coal fires, while heating was transferred conductively from adjacent parts of ignited coal seams. The fluid (gas) regime in the zones of combustion was controlled by the CCO buffer at excess atomic carbon. Paralava melts exposed to high-temperature extremely reducing conditions contained droplets of immiscible Fe–S–P–C, Fe–S, Fe–P, and Fe–P–C melts, which then crystallized into reduced mineral assemblages. Full article

This study examines the role of bulk cargo ports in improving supply chain efficiency within the Bohai Rim port cluster in China, addressing a gap in the research that has primarily focused on container ports. By analyzing 13 ports in the cluster through the shiftrate model and network analysis, this research aims to understand their adaptation to changing trade patterns and economic conditions. The Bohai Rim is a key hub for four major bulk cargo types—grain, coal, oil, and ore—each with distinct growth rates and trade networks. This research classifies the ports into four tiers based on their operational capabilities and market influence. Key findings reveal that the cargo transport network has shifted from a tri-power structure (Dalian, Tianjin–Tangshan, Qingdao–Rizhao port groups) to a dual-core pattern, now led by Tangshan and Qingdao Ports. Qingdao Port, with its advanced technologies and international orientation, has become a central player in global dry bulk transport. This shift reflects the changing dynamics of regional trade, with Qingdao’s port technologies and global connectivity positioning it as a leader in the industry. This study provides valuable insights for port authorities, helping them understand the evolution of port systems and enhance the efficiency of neighboring ports. Full article

On the evening of 31 March 2019, Parsa and Bara Districts in central Nepal were severely hit by a wind storm which was the first documented tornadic incidence in Nepal.In this paper, we investigate the background of the tornado formation via numerical simulations with the WRF-ARW model. The results show that: (1) a flow situation favorable to the generation of mesocyclones was formed by a combination of local plain-to-mountain winds consisting of warm and humid southwesterly wind in the lower atmosphere and synoptic northwesterly wind aloft over the southern foothills of the Himalayan Mountain range, leading to significant vertical wind shear and strong buoyancy; (2) the generated mesocyclone continuously shed rain-cooled outflow with 600∼800 m depth above the ground into the Chitwan valley while moving southeastward along the Mahabharat Range at the northeastern rim of the Chitwan valley; (3) the cold outflow propagated in the valley, forming a front; and (4) the tornado was generated when this cold outflow passed over the Siwalik Hills bordering the southern rim of the Chitwan valley. At this point, descending flow around a high mountain generated positive vertical vorticity near the ground; blocking by this high mountain and channeling through a mountain pass enhanced updrafts at the front by forming a hydraulic jump. These updrafts amplified the positive vertical vorticity via stretching, and this interaction of the cold outflow with the Siwalik Hills contributed to tornadogenesis. The simulated location and time of the disaster showed generally good agreement with the reported location and time. Full article

The heterobimetallic 15-MC-5 metallacrown of formula [CeCu₅(5mpzHA)₅(NO₃)(H₂O)₇]·2NO₃·7H₂O, designated MC-Ce, was synthesized using 5-methyl-2-pyrazinehydroxamic acid (5mpzHA) as a linker, reacting with Ce^III and Cu^II salts under mild conditions. Single-crystal X-ray diffraction analysis reveals a crown-like [Cu₅Ce(5mpzHA)₅] core, characteristic of a 15-MC-5 system, with five Cu^II atoms at the rim of the crown and the Ce^III ion occupying the dome of the crown, with water molecules, oxygen atoms and one nitrate anion filling the nine-coordination sphere around the Ce^III ion, which exhibits a distorted spherical tricapped trigonal prism geometry. The thermogravimetric analysis evidences successive mass losses due to the removal of water molecules and decomposition of the structure after 217 °C, whereas the PXRD analysis of the thermal decomposition residue reveals the presence of copper and copper/cerium oxide particles. These nanocomposite materials were also synthesized using the metallacrown MC-Ce under a hydrothermal method in the presence of multi-walled carbon nanotubes (MWCNTs), affording insights that this metallacrown can act as a source precursor for the synthesis of these mixed cerium/copper oxide nanomaterials. The experimental χMT value in MC-Ce at room temperature is 3.175 cm³ mol⁻¹ K, which is higher than the calculated one for one magnetically isolated Ce^III plus five Cu^II ions, probably due to the antiferromagnetic interactions among Cu^II ions within the metallacrown hoop plus the thermal depopulation of JZ sublevels of Ce^III ground state (5/2), which exhibit a small splitting under the anisotropic ligand field effects. The χMT decreases continuously until it reaches the value of 0.80 cm³ mol⁻¹ K at 10 K, reinforcing the presence of intramolecular antiferromagnetic interactions. Full article

We demonstrate that at the rim of the photon sphere of a black hole, the quantum statistics transition takes place in any multi-particle system of indistinguishable particles, which passes through this rim to the inside. The related local departure from Pauli exclusion principle restriction causes a decay of the internal structure of collective fermionic systems, including the collapse of Fermi spheres in compressed matter. The Fermi sphere decay is associated with the emission of electromagnetic radiation, taking away the energy and entropy of the falling matter without unitarity violation. The spectrum and timing of the related e-m radiation agree with some observed short giant gamma-ray bursts and X-ray components of the luminosity of quasars and of short transients powered by black holes. The release of energy and entropy when passing the photon sphere rim of a black hole significantly modifies the premises of the information paradox at the falling of matter into a black hole. Full article

Tsunami maps provide critical information about tsunami hazards, potential inundation areas, and safe evacuation routes, yet little research has addressed how different user groups perceive and interpret these maps. Using a questionnaire distributed to 181 participants (24 experts—EXs and 157 general users—GUs) and the chi-square (χ²) test, this research explored their understanding and perception of map elements, symbology, probabilistic data, and uncertainty communication. The results show that while both groups generally understand the maps, significant differences exist in their perception of essential map elements, such as evacuation routes, safe zones, and technical data. On average, EXs identified 7.38 elements that evacuation maps should contain, consistently emphasizing the need for more detailed information, whereas GUs preferred simplicity, selecting an average of 5.11 elements. These results highlight the need to balance detail and clarity in map design to serve both user groups effectively. Notably, the results suggest that at least 33% of EXs and 47% of GUs did not clearly distinguish between tsunami hazard and evacuation maps, highlighting the need for clearer map design and terminology. The study also revealed challenges in communicating probabilistic data and uncertainty to non-experts, suggesting the need for improved methods to present this information effectively. Full article

Cinnamic acid (CA) has many beneficial effects on human health. However, its poor water solubility (0.23 g/L, at 25 °C) is responsible for its poor bioavailability. This drawback prevents its clinical use. To overcome the solubility limits of this extraordinary natural compound, in this study, we developed a highly water-soluble inclusion complex of CA with randomly methylated-β-cyclodextrin (RAMEB). The host-guest interaction was explored in liquid and solid states by UV-Vis titration, phase solubility analysis, FT-IR spectroscopy, and ¹H-NMR. Additionally, molecular modeling studies were carried out. Both experimental and theoretical studies revealed a 1:1 CA/RAMEB inclusion complex, with a high apparent stability constant equal to 15,169.53 M⁻¹. The inclusion complex increases the water solubility of CA by about 250-fold and dissolves within 5 min. Molecular modeling demonstrated that CA inserts its phenyl ring into the RAMEB cavity with its propyl-2-enoic acid tail leaning from the wide rim. Finally, a biological in vitro study of the inclusion complex, compared to the free components, was performed on the neuroblastoma SH-SY5Y cell line. None of them showed cytotoxic effects at the assayed concentrations. Of note, the pretreatment of SH-SY5Y cells with CA/RAMEB at 10, 30, and 125 µM doses significantly counteracted the effect of the neurotoxin MPP⁺, whilst CA and RAMEB alone did not show any neuroprotection. Overall, our data demonstrated that inclusion complexes overcome CA solubility problems, supporting their use for clinical applications. Full article

The research presented in this paper takes another step towards developing methods for automatic condition verification to detect structural damage to vehicle wheel rims. This study presents the utilisation of vibration spectra via Fast Fourier Transform (FFT) and a neural network’s learning capabilities for evaluating structural damage. Amplitude and time cycles of acceleration were analyzed as the structural response. These cycles underwent FFT analysis, leading to the identification of four diagnostic symptoms described by 20 features of the diagnostic signal, which in turn defined a condition vector. In the subsequent stage, the amplitude and frequency cycles served as input data for the neural network, and based on them, self-organizing maps (SOM) were generated. From these maps, a condition vector was defined for each of the four positions of the rim. Therefore, the technical condition of the wheel rim was determined based on the variance in condition parameter features, using reference frequencies of vibration spectra and SOM visualisations. The outcome of this work is a unique synergetic diagnostic system with innovative features, identifying the condition of a wheel rim through vibration and acoustic analysis along with neural network techniques in the form of Kohonen maps. Full article

Bacterial liver parenchymal infections in dogs are rarely documented, and their imaging characteristics are scarce in the veterinary literature, especially in Computed Tomography (CT). This retrospective multicentric study aimed to describe the CT characteristics of parenchymal bacterial liver infection and abscessation in dogs and compare them with the human literature. Twenty dogs met the inclusion criteria. All dogs, except one, showed discrete hepatic lesions consistent with pyogenic liver abscess (19/20). A single case showed diffuse liver changes, which was diagnosed with granulomatous bacterial hepatitis (1/20). Multifocal lesions were associated with the presence of abdominal pain (p = 0.023). CT characteristics of pyogenic liver abscesses in our study resemble those described in the human literature, with multifocal (14/19) or single (5/19), round or ovoid (19/19), hypoattenuating hepatic lesions, which are better visualised in post-contrast images. Pyogenic liver abscesses can also show features such as the “cluster sign” (8/19), transient arterial segmental enhancement (6/10), rim enhancement (6/19), and intralesional gas (4/19). Additional CT findings, such as local lymphadenomegaly (18/20), peritoneal fat stranding (14/20), and peritoneal fluid (13/20), are also commonly observed. Full article