Open Cavity Research Articles

Trunk climbing among ground-dwelling European amphibians – first observation from Poland

Most European amphibian species are considered land-dwelling, associated with moving along the ground and as poor climbers. However, more recent research indicates that non-arboreal amphibians use nesting boxes and tree hollows in Central and Western Europe. This study describes the first observation of tree climbing by the common toad Bufo bufo (Linnaeus, 1758) and common frog Rana temporaria Linnaeus, 1758 in Poland. While conducting a night survey of newt mortality in the ‘Traszki Ratajskie’ protected area in an urban park in the city of Poznań, Poland, we detected the unexpected use of trees by two species of amphibians. In June 2020, we observed cases of Bufo bufo and Rana temporaria foraging on and using arboreal ambush sites. The toads were found at an average height of 124 cm above the ground, and the frogs at 35 cm, on the tree trunks and branches of two willows (Salix cfr. alba L.) and a dead silver birch specimen (Betula pendula L.). The willows had an extensive multi-stem structure, and exhibited signs of maturity and ageing (hollow-bearing trees with open cavities and crevices). This is the first observation of arboreal behaviour in B. bufo and R. temporaria in Poland. The climbing behaviour and use of tree sites were likely linked to the search for a humid shelter provided by the interior of the ageing trees, as well as to the foraging behaviour that we observed. Trees exhibiting signs of maturity usually have complex structures, and seem particularly important for amphibians during periods of drought, as both a suitable shelter and an area from which to ambush prey. We recommend focusing greater attention on the protection of mature, ageing trees, especially Salix spp. within a terrestrial buffer zone of at least 250 metres from ponds, as these are poorly researched components within amphibian habitats. This type of resource may be essential for long-term amphibian conservation due to site fidelity and the limited number of shelters in human-altered landscapes. The recently adopted EU Nature Restoration Law presents an opportunity to develop good practices in this area, particularly urban tree planting and habitat management.

Polaritonic Chemistry Enabled by Non‐Local Metasurfaces

AbstractVibrational strong coupling can modify chemical reaction pathways in unconventional ways. Thus far, Fabry‐Perot cavities formed by pairs of facing mirrors have been mostly utilized to achieve vibrational strong coupling. In this study, we demonstrate the application of non‐local metasurfaces that can sustain surface lattice resonances, enabling chemical reactions under vibrational strong coupling. We show that the solvolysis kinetics of para‐nitrophenyl acetate can be accelerated by a factor of 2.7 by strong coupling to the carbonyl bond of the solvent and the solute with a surface lattice resonance. Our work introduces a new platform to investigate polaritonic chemical reactions. In contrast to Fabry‐Perot cavities, metasurfaces define open optical cavities with single surfaces, which removes alignment hurdles, facilitating polaritonic chemistry across large areas.

Heterometallic-Organic Cages with Customized Cavities: Constructed by Bottom-Up Step-Wise Coordination-Driven Self-Assembly.

Accurately synthesizing coordination-driven metal-organic cages with customized shape and cavity remains a great challenge for chemists. In this work, a bottom-up step-wise coordination-driven self-assembly approach was put forward. Employing this strategy, three terpyridyl heterometallic-organic truncated tetrahedral cages with different sizes and cavity were precisely synthesized. Firstly, the coordination of tripodal organic ligands with Ru2+ afforded dendritic metal-organic ligands L1-L3. Then the Ru building blocks complexed with Fe2+ and shrunk to form the desired heterometallic-organic cages (C1-C3). These discrete heterometallic-organic supramolecular cages were fully characterized and displayed the large and open cavities varied from 7205 Å3 to 9384 Å3. Notably, these cages could not be directly constructed by single-step assembly process using initial organic ligands or dimeric metal-organic ligands, indicative of the irreplaceability of a bottom-up step-wise assembly strategy for size-customized architectures. This work paves a new way for precisely constructing metal-organic cages with well-defined cavities.

Investigation of Purcell enhancement of quantum dots emitting in the telecom O-band with an open fiber cavity

Investigation of Purcell enhancement of quantum dots emitting in the telecom O-band with an open fiber cavity

How compactness affects long bone resistance to compression-An investigation into the rhinoceros humerus.

The functional signal of bone internal structure has been widely studied. Isolated form-function relationships have often been assumed from the observation of presumed morphofunctional relationships, but have never been truly tested. Indeed, distinct bone microanatomical feature co-evolve in response to various constraints that are difficult to detangle. This study tested for the first time the impact of various microanatomical parameters taken one by one, plus some in pairs, on bone strength under compression using biomechanical modelling. We carried out finite element analyses on humerus models, obtained from a white rhinoceros, with different heterogeneous internal structures, and analysed the magnitude and distribution of von Mises stresses. These tests validated earlier hypotheses of form-function relationships about the greater resistance to compression provided by the thickening of the cortex and the filling of the medullary area by trabecular bone and highlighted the stronger impact of increasing trabecular bone compactness than of avoiding an open medullary cavity. By making it possible to estimate the relative impact of each parameter and ofcombinations of microanatomical features, they also showed the more limited impact of the trabecular bone compactness in the epiphyses to resist compression, and the fact that microanatomical changes of opposite but of similar amplitude impact can compensate each other, but that the impact of the sum of two negative microanatomical changes far exceeds the sum of the impacts of each of the two changes taken separately. These results contribute to a better understanding of bone adaptation and form-function relationships so that they later can be used with confidence for palaeobiological inferences on fossil specimens, contributing to a better understanding of skeletal evolution during the evolutionary history of vertebrates. They also highlight the potential of taking internal structure into account in the bone biomechanical analyses. In addition, they can be used in bioinspiration to design resistant structures subjected to compression.

Optimization of piezo pump and air impact cooling based on a synthetic jet

A synthetic jet piezo (PE) pump with an inlet channel structured akin to a diffuser/nozzle, featuring smoothed walls, was developed. The synthetic jet was characterized by analyzing the internal flow field of the PE pump. Furthermore, the flow performance of this novel PE pump was compared with that of a basic PE pump, thereby demonstrating the advantages of the proposed design. Utilizing regression equations and standardized effect plots derived from the response surface method, both the main and interaction effects of parameters on the flow rate were assessed. Subsequently, the flow performance of the optimized PE pump was evaluated through experimental testing. Additionally, air impact cooling experiments were conducted, focusing on the influence of the impact distance on cooling performance. The findings indicated that the PE pump's open cavity height, closed cavity height, outlet diameter, and orifice diameter were 1.3 mm, 0.5 mm, 1.5 mm, and 0.8 mm, respectively. The proposed synthetic jet PE pump achieved a flow rate of 1832.3 ml/min at 50 Vpp and 4.6 kHz. Furthermore, it was observed that the operation of the PE pump reduced the temperature of the heater by 63 % at an impact distance of 20 mm.

Sensitivity-enhanced optical fiber sensor based on the Vernier effect for detection of ammonia in water

A sensitivity-enhanced optical fiber sensor for the detection of dissolved ammonia in water based on the Vernier effect is proposed and demonstrated. The sensor comprises a sensing Fabry-Perot interferometer (S-FPI) and a reference Fabry-Perot interferometer (R-FPI) in parallel. The S-FPI is an open cavity fabricated by the dislocation welding of single-mode fiber(SMF), which is filled with a mixture of ultraviolet-curable resin NOA 170 and Oxazine 170 perchlorate (O17). The R-FPI is a sealed cavity, which is constructed by fusion splicing of SMF and hollow core fiber (HCF). The proposed sensor is based on the chemical reaction between the dissolved ammonia and O17. This chemical reaction alters the refractive index (RI) of the S-FPI, resulting in a wavelength shift of the reflected spectrum. The two interferometers exhibit a nearly identical free spectral range (FSR), thereby enabling the generation of the Vernier effect, which markedly enhances the ammonia sensitivity of the sensor. Experimental results indicate that the sensor sensitivity is 0.34 nm/ppm in the dissolved ammonia range of 5-40 ppm, which is approximately 9.1 times that of the single S-FPI. The proposed sensor exhibits both good repeatability and a short response time, in addition to selectivity for the detection of ammonia.

Dispersion-free characterization of terahertz slab–waveguide modal confinement based on a metal Bragg grating structure

Photonic waveguide structures that use periodic metal grooves and periodically perforated metal slits (PPMSs) can laterally confine Sommerfeld and Zenneck surface waves of metals with the electric field accumulation among metal interspaces in the terahertz (THz) region, instead of the total internal reflection principle of dielectric slab media. For the efficiency enhancements of THz-wave coupling and slab–waveguide confinement, specific integrators with high refractive indices or specified for input angles of transverse magnetic polarized waves, such as prisms, metal blades, and waveguides, are requested to excite spoof surface plasmons in the THz region. However, the integrator-assembled slab–waveguides encounter challenges of THz pulse-wave communication in compact and low-distortion systems. A resonant waveguide grating structure based on PPMSs is experimentally demonstrated to confine THz lateral waves from the plane-wave radiation in free space. The open frame and periodic metal cavities of PPMSs can work as a slab–waveguide to transmit structural confined waveguide modes with forwarding evanescent waves of Fabry–Pérot resonance. For 0.1–1 THz waves, the short wavelengths that are both less than half the metal slit width and 3.75 times the metal thickness can lead to zero dispersion and the highest confinement factor in a slab–waveguide for PPMS-confined THz waves. This behavior is opposite to the high structural dispersion in confined THz waves of surface plasmonic devices.

2D CrSBr Enables Magnetically Controllable Exciton‐Polaritons in an Open Cavity

Abstract 2D van der Waals (vdW) layered materials exhibit significant exciton binding energy and versatile stacking options, making them ideal for room‐temperature exciton‐polariton devices used in low‐threshold lasing, nonlinear optical switching, and quantum computing. However, most existing systems depend on external optical microcavities coupled with single monolayers, leading to limited controllability and increased costs. Here, external cavity‐free vdW magnet CrSBr crystals are presented that feature magnetically controllable self‐hybridized exciton‐polaritons that remain stable up to room temperature. The ultrastrong exciton‐photon coupling suppresses donor‐, phonon‐, and defect‐related emissions. Furthermore, the exciton‐polariton dispersion and emission spectra can be effectively controlled by adjusting the magnetic field, temperature, and CrSBr thickness. This vdW exciton‐polariton material platform, demonstrating remarkable magnetic responsiveness in open cavity configurations under ambient conditions, paves the way for the development of compact, fast, and low‐loss spin, quantum, and magneto‐photonic devices.

Natural Convection in an Open and Wavy Porous Cavity Submitted to a Partial Heat Source

Natural Convection in an Open and Wavy Porous Cavity Submitted to a Partial Heat Source

Thermal convection subjected to perturbations from the bottom of a top open cavity

Perturbations are very common in the transition and heat transfer of thermal convection in nature and industry. Accordingly, thermal convection on a top-open cavity subjected to periodic and random perturbations is investigated using three-dimensional numerical simulation. A great number of numerical experiments are performed at various Rayleigh numbers and a fixed Prandtl number of 0.71 by introducing periodic and random numerical perturbations. Numerical results demonstrate that there exists the effect of periodic perturbations on the transition route over 3.5 × 103 ≤ Ra ≤ 8.5 × 104. That is, the transition route to chaos is sensitive to the amplitude of random perturbations for, e.g., 0.01 ≤ Ar ≤ 0.05, which is also characterized. Furthermore, heat transfer enhancement under periodic and random perturbations is quantified with the scaling law. This study sheds new light on the influence of periodic and random perturbations on thermal convection on the top-open cavity below heating. The possibility to control heat transfer is revealed by introducing random perturbations on the bottom of the top-open cavity.

Mixed matrix membrane for hydrogen separation enhanced by Oxacalix[4]arene-Containing porous organic polymers

The mixed matrix membranes (MMMs) have great potential for industrial H2 enhancement applications. However, some challenges remain to incorporate the nanoporous architectures with industrial processable polymers. In this work, a macrocyclic cavitand from oxacalix[4]arene was integrated into porous polymers via a facile ring-opening-metathesis polymerization (ROMP), the resulting BIT-POP-20 was added to polysulfone matrix to make novel MMMs with different mass ratios. These membranes improved gas permeation rate for CO2, H2 and He, compared with pristine polysulfone, and high H2/N2 selectivity of 105 was achieved. This huge improved H2/N2 separation performances were due to the nanoporous gas passages through the open supramolecular cavities. This work presents an interesting example in designing MMMs using intrinsic macrocyclic cavity in porous polymer backbone that helps increase their performances in gas separations.

A fast vibro-acoustic modeling method of plate-open cavity coupled systems

In this paper, a fast Chebyshev-Ritz method for vibro-acoustic analytical modeling of plate-open cavity coupled systems is developed for the first time. Based on the Chebyshev spectral method and the Rayleigh-Ritz solution procedure, the vibro-acoustic model of the open cavity coupled with a rectangular plate is established. The exterior acoustic field of the open cavity is expressed by the Rayleigh integral. Additionally, the Rayleigh integral is divided into a frequency-independent singular integral and a frequency-dependent non-singular integral, accelerating the calculation process. Furthermore, the Gauss-Chebyshev-Lobato sampling method is first developed for the plate-open cavity coupling model. By converting the integrals into tensor products, the method avoids complex quadruple integrals, increasing the efficiency of the entire integral operation. The vibration and acoustic responses from the proposed method agree well with existing literature and FEM analysis results, demonstrating the convergence and correctness of the current methodology. The mechanism of cavity depth on vibro-acoustic features of plate-open cavity systems is studied, which is less focused in the published literature. Other factors governing the plate-open cavity coupled model encompassed boundary conditions, fluid mediums, and plate thickness are fully examined. The results provide a theoretical foundation for the design and future research of plate-open cavity structures.

Polaritonic Chemistry Enabled by Non-Local Metasurfaces.

Vibrational strong coupling can modify chemical reaction pathways in unconventional ways. Thus far, Fabry-Perot cavities formed by pairs of facing mirrors have been mostly utilized to achieve vibrational strong coupling. In this study, we demonstrate the application of non-local metasurfaces that can sustain surface lattice resonances, enabling chemical reactions under vibrational strong coupling. We show that the solvolysis kinetics of para-nitrophenyl acetate can be accelerated by a factor of 2.7 by strong coupling to the carbonyl bond of the solvent and the solute with a surface lattice resonance. Our work introduces a new platform to investigate polaritonic chemical reactions. In contrast to Fabry-Perot cavities, metasurfaces define open optical cavities with single surfaces, which removes alignment hurdles, facilitating polaritonic chemistry across large areas.

Kinetic Gas Hydrate Inhibition by Alternating Dipeptoids with Optimal Size and Shape N-Substituents.

Current commercial kinetic hydrate inhibitors (KHIs) are all based on water-soluble polymers with amphiphilic alkylamide or lactam groups. The size and shape of the hydrophobic moiety are known to be critical for optimum KHI performance. Proteins and peptides represent an environmentally friendly alternative, especially as bioengineering could be used to manufacture a product predetermined to have optimum KHI performance. Here, we explore a new series of polymers that are alternating dipeptoids where one of the peptide links originates from glycine. The dipeptoids contain n-propyl groups on the nitrogen atom and varying size and shape alkyl side chains on the neighboring carbon atom. Experiments were carried out in high-pressure steel rocking cells using the slow constant cooling (SCC) test method (1 °C/h) and a synthetic natural gas mixture. All the dipeptoids showed good KHI performance with the best result being for that with a glycine-N-propylleucine repeating unit (Poly iC4-Pr), which has pendant iso-butyl groups on the carbon atom. It exhibited the same KHI performance as poly(N-vinyl caprolactam). Dipeptoids with smaller or longer alkyl groups than iso-butyl gave worse performance. It is conjectured that the iso-butyl group is the optimal carbon length for this polymer class. In addition, the end-branching maximizes the van der Waals interaction with open cavities on growing hydrate particles, which must occur without loss of hydrogen-bonding from the neighboring peptide linkage for optimum KHI performance. Thus, the study provides further evidence for the premise that good KHI molecules must contain multiple amphiphilic groups (often as polymers) with optimal size and shape hydrophobic groups adjacent to strong hydrogen bonding groups. The solvent, n-butyl glycol ether, was shown to be a synergist for Poly iC4-Pr, lowering the onset temperature of hydrate formation in SSC tests relative to the polymer alone.

A giant solitary fibrous tumor of the abdominal pelvic cavity: A case report and literature review.

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor, especially the giant one from the abdominal pelvic cavity. We report on a rare case of a giant SFT of the abdominal pelvic cavity to review the existing literature in detail to improve the diagnosis and treatment of SFT. The patient is a 52-year-old female who presented with 2 weeks of abdominal distension. Abdominal magnetic resonance imaging showed a giant mass (>20 cm) in the abdominal pelvic cavity, considered a mesenchymal tumor. She denies a history of tumor disease. A whole abdomen bulge and a mass of about 18 cm × 10 cm on the right side and middle side were found in the physical examination after admission. Abdominal enhanced computed tomography revealed a giant cystic-solid mass located on the middle and right side of the abdominal pelvic cavity, measuring approximately 20.4 cm × 11.7 cm, with multiple cystic changes and necrosis and compression of adjacent organs and tissues, and marked inhomogeneous enhancement. The patient underwent an open abdominal pelvic cavity giant tumor operation to achieve a radical resection, and did not undergo chemotherapy or radiotherapy. The patient underwent open complete resection of a giant abdominal pelvic tumor with no complications and was diagnosed as SFT according to the pathology, immunohistochemistry showed that the tumor tested positive for CD34(+), STAT-6(+), and Ki-67 (10%). Abdominal computed tomography scans were performed 6 months after resection, and no signs of recurrence or metastasis were found. The clinical symptoms and imaging features of giant abdominal pelvic cavity SFT are not typical. Preoperative diagnosis is difficult and has the potential for malignancy. Based on the results of the current study, there is no standard treatment strategy around the world and the therapeutic effect of radiation therapy and chemotherapy is relatively limited. Thus, complete surgical resection and close clinical follow-up are advocated.

Effects of doors on an open cavity flow at Mach number 6

Open cavities with different door-opening angles are investigated using high-speed schlieren visualization and dynamic pressure measurements in hypersonic flow with a freestream Mach number of 6. With the help of numerical simulations, the shear layer deformation and pressure increase in the cavities due to the impingement of the door-leading-edge shocks are identified via comparison with those in the cavity without doors. As the door-opening angle decreases from 90°, the shear layer above the forepart of the cavity is gradually raised by the high pressure in the cavity. When the door-opening angle decreases to 30°and 15°, the boundary layer on the upstream flat plate of the cavity separates, and separation shock is observed. The doors enhance the instability of the cavity flow and increase the pressure fluctuations in the cavities. A new oscillation pattern, referred to as coupled oscillation, is observed in the cases with separation on the upstream flat plate, in which the separation shock oscillates at the same dominant frequency as the flow inside the cavity. Compared with the cavity without doors, this coupled oscillation causes a lower oscillation frequency and a larger overall sound pressure level. Cross-correlation analyses between pressure signals indicate that the disturbances generated at the trailing edge of the cavity can propagate to the separation on the upstream flat plate and cause coupled oscillation of the separation shock. The fundamental frequencies of the coupled oscillations can be normalized to approximately the same Strouhal number as that of the cavity without doors. These findings support that the oscillation mechanisms of hypersonic cavities without and with doors are primarily dominated by acoustic feedback.

Mixed convective heat transfer in an open cavity with fins

AbstractThis work numerically explores the mixed convective heat transfer in an open square enclosure containing conducting fins fixed to the heated vertical wall. This kind of work with fins has enormous potential due to its applications in research, engineering, and current industries. Therefore, the current work is highly significant to understand the impact of mixed convection. The external flow enters from the hole in the bottom wall and leaves from the hole in the upper wall. The left vertical wall of the enclosure is heated isothermally, and the fins are attached to the heated walls at a uniform height. Both the upper and lower walls are adiabatic, whereas the right sidewall is at a lower temperature. The non‐dimensional transport equations are resolved by using the finite element method. The study is accomplished for the wide control variables range, such as Reynolds number (50 ≤ Re ≤ 200), Richardson's number (0.1 ≤ Ri ≤ 10), the length of the fins (Lf = 0.2, 0.4, and 0.6), the size of the outlet opening (Wout = 0.1, 0.2, and 0.3), and the gaps in between the outlet hole and left heated wall (S = 0, 0.45, and 0.9). The results show that the thermal performance of the open enclosure is meaningfully affected by the control parameters. The maximum and minimum heat transfer happens when the position of the outlet opening is at the left (S = 0) and right (S = 0.9), respectively. The heat transfer improves by raising the Ri and Re, whereas increasing the fin's length and distance between the outlet opening and left wall reduces heat transfer significantly. The rises 13% with a decrease in the fin's length from 0.6 to 0.2 at Re = 200, S = 0 due to the improvement of the convection on the heated wall. Also, increases by 15% when Ri increases from 1 to 9.

MHD conjugate mixed convection along with internal heat generation and Joule heating in a closed/open cavity with rotating solid cylinder

PurposeThis study aims to investigate magnetohydrodynamic (MHD) conjugate pure mixed convection considering interior heat production and resistive heating inside a square closed/open cavity featuring a rotating cylinder for aiding (clockwise) and opposing (counterclockwise) flow configurations. Moreover, the impacts of altering cylinder size and conductivity on the system’s overall performance to determine optimum conditions are examined in this investigation.Design/methodology/approachThe closed chamber is differentially heated by keeping high and low temperatures at the vertical boundaries. In contrast, the open cavity has a heated left wall and an open right boundary. The Galerkin finite element method is used to solve the Navier–Stokes and the thermal energy equations, which construct the present study’s mathematical framework. Numerical simulations are conducted for the specified ranges of several controlling parameters: Reynolds (31.62 ≤ Re ≤ 1000), Grashof (103 ≤ Gr ≤ 106) and Hartmann numbers (0 ≤ Ha ≤ 31.62), and volumetric heat generation coefficient (Δ = 0, 3).FindingsWhen Gr, Re and Ha simultaneously increase, the average Nusselt number along the warmed boundary rises accordingly. Conversely, interior heat production lowers heat transmission within the computational domain, which is also monitored regarding mean fluid temperature, overall entropy production and thermal performance criterion. Finally, the open cavity confirms better thermal performance than the closed cavity.Originality/valueComprehending the impacts of the magnetic field, Joule heating, internal heat generation and enclosed or open boundary on pure MHD combined free-forced convective flow offers valuable understandings of temperature fluctuations, velocity propagations, heat transport and irretrievable energy loss in numerous engineering applications.

Bénard–Marangoni Convection in an Open Cavity with Liquids at Low Prandtl Numbers

Bénard–Marangoni Convection in an Open Cavity with Liquids at Low Prandtl Numbers