Search Results (227)

This paper develops an analytical treatment of vibro-acoustic wave propagation in a cylindrical waveguide containing two clamped elastic membranes and a central flexible-shell segment. The acoustic field obeys the time-harmonic Helmholtz equation, the shell motion is described by Donnell–Mushtari thin-shell theory under axisymmetric loading, and the membrane response is governed by classical membrane theory and incorporated through a tailored Galerkin scheme. The resulting coupled fluid–structure boundary-value problem is solved by the Mode-Matching Method: the acoustic potentials are expanded in orthogonal radial eigenfunctions within each subregion, and continuity of pressure, normal velocity, and structural displacement are enforced at every interface. The mirror symmetry of the configuration is exploited by an exact decomposition into symmetric and anti-symmetric sub-problems, each of which reduces to a truncated linear algebraic system of dimension $4N+4$ for the unknown modal amplitudes. Acoustic power-balance identities provide a quantitative consistency check on the numerical implementation and diagnose convergence with respect to the truncation order; structural damping is accommodated through complex-modulus substitutions for the shell and the membrane tension without altering the algebraic structure of the system. The numerical results demonstrate that the dual-membrane configuration delivers transmission-loss values exceeding $25\mathrm{dB}$ across the low-frequency band relevant to HVAC and automotive applications, with a representative plateau near $13\mathrm{dB}$ at the reference geometry, through resonance-driven modal coupling between the acoustic field and the compliant interfaces. Parametric studies identify the excitation frequency, the inner-membrane radius, the shell radius, and the chamber length as effective design parameters for tuning the attenuation. The formulation furnishes a unified and computationally efficient analytical tool for predicting and optimising noise attenuation in flexibly coupled cylindrical duct systems. Full article

Maropitant has been proposed as an adjunct for pain relief in dogs undergoing surgeries like ovariohysterectomy (OVH), but its effectiveness has not yet been definitively proven. This study aimed to assess the intraoperative analgesic effect of intravenously administered maropitant citrate at a constant rate infusion through monitoring parasympathetic tone activity in female dogs undergoing OVH. Thirty healthy females of various breeds, with an average age of 3.8 ± 2.7 years, an average weight of 16.75 ± 10.68 kg, were randomly assigned to two treatment groups. The group receiving maropitant (G_Maro, n = 15) was given a 1 mg kg⁻¹ maropitant bolus intravenously (IV), followed by a continuous infusion of 100 mcg kg⁻¹ min⁻¹. The lidocaine group (G_Lido, n = 15) received a 2 mg/kg lidocaine IV bolus, with subsequent infusion at 50 mcg kg⁻¹ min⁻¹. Cardiorespiratory variables and the PTA index were evaluated at 11 anesthetic time points. Overall, cardiovascular variables such as Heart Rate (HR) and systolic arterial pressure (SAP) significantly decreased during anesthesia induction in the G_Maro (p = 0.0001; p = 0.01, respectively) and in G_Lido (p = 0.01). Differences between groups during induction were observed in HR (p = 0.03), SAP (p = 0.04), and mean arterial pressure (MAP) (p = 0.03). MAP showed significant changes from baseline at the start of surgery and during clamping in both G_Maro (p = 0.03) and G_Lido (p = 0.003). Regarding ventilatory variables—pulse oximetry (SpO₂), respiratory rate (RR), inspired oxygen fraction (FiO₂), end-tidal CO₂ (EtCO₂)—no group differences were found, but RR (G_Maro; p = 0.001, G_Lido; p = 0.0001) and SpO₂ (G_Maro; p = 0.004, G_Lido; p = 0.04) differed significantly from baseline due to the controlled clinical setting. During anesthesia maintenance, end-tidal isoflurane (ET_Iso) increased significantly in the G_Lido (p = 0.009), with no difference between groups (p = 0.94). Finally, only the PTA energy variable showed a significant decrease in the G_Maro (p = 0.0006), and a significant difference in this parameter was observed during right ovarian pedicle manipulation between groups (p = 0.02). In conclusion, continuous intravenous infusion of maropitant citrate at 100 mcg kg⁻¹ h⁻¹ effectively reduced the sympathetic response related to nociception, similar to lidocaine, in healthy female dogs undergoing OVH. Full article

Background: Preterm infants with bradycardia at birth often undergo immediate cord clamping (ICC) followed by resuscitation with positive pressure ventilation (PPV), chest compressions (CCs) and umbilical venous catheter (UVC) epinephrine. Resuscitation with an intact cord (PPV during delayed umbilical cord clamping—DCC) stabilizes cardiac output but delays UVC placement. Objective: To evaluate the feasibility of direct epinephrine injection into the umbilical vein during DCC (DCC + direct-epinephrine) compared with ICC and epinephrine administered through a UVC (ICC + cath-epinephrine), and to explore differences in return of spontaneous circulation (ROSC) and need for CCs between these approaches. Methods: Eleven preterm lambs (125–127 d gestation) were asphyxiated by cord compression to decrease heart rate (HR) to <30/min. In the ICC + cath-epinephrine group, the cord was immediately cut, lambs received PPV followed by CCs if HR < 60/min, and epinephrine was administered after UVC placement. In the DCC + direct-epinephrine group, cord compression was released when HR < 30/min and PPV was initiated. If HR remained <60/min, epinephrine was injected into the UV using a 25G needle. If ROSC was achieved, DCC was continued for 2 min. If HR < 100/min, the cord was cut and resuscitation was continued as outlined above. Plasma epinephrine concentrations were analyzed. Results: All lambs required epinephrine. Time to epinephrine was shorter with DCC + direct-epinephrine, 1.0 (0.7, 1.6) vs. 3.7 min (3.2, 5.2). Fewer lambs with DCC + direct-epinephrine needed CC (2/6 vs. 5/5, p = 0.06). ROSC success and plasma epinephrine concentrations were similar. Post-ROSC, heart rates and mean blood pressures tended to be higher in the ICC + cath-epinephrine group. Conclusions: In this perinatal lamb model of asphyxial bradycardia, resuscitation with an intact cord with direct umbilical venous epinephrine injection is feasible. Larger studies are required to determine whether this approach reduces the need for CC or improves clinically meaningful outcomes. Full article

The rapid increase in memory power density has made memory thermal management a critical challenge in high-density servers, where extremely limited DIMM spacing significantly reduces the effectiveness of air cooling. Compared with CPUs and GPUs, memory-level liquid cooling has received less systematic study, particularly regarding the influence of cold plate structural design on thermal and hydraulic performance under realistic server conditions. In this paper, three engineering-feasible memory liquid cooling solutions (water-flowing cold plate, clamp-type cold plate and heat-pipe-based cold plate) are experimentally compared on a high-density server system. Experiments are conducted at coolant inlet temperatures of 37–50 °C with a fixed flow rate of 0.8–1.5 L/min. Memory, CPU, and voltage regulator temperatures, as well as system pressure drop, are measured. Results show that memory temperature increases with coolant inlet temperature for all configurations, while their relative performance remains unchanged. Memory temperatures range from 62.04 to 71.13 °C, 57.65 to 66.98 °C, and 66.22 to 76.07 °C, with corresponding pressure drops of 24.19–26.69 kPa, 32.73–35.98 kPa, and 27.00–29.96 kPa. These results provide insight into the role of coolant distribution and flow-path topology in memory thermal performance. Full article

Background/Objective: Continuous blood pressure (BP) monitoring is essential in clinical settings, where rapid hemodynamic changes influence patient management. While intra-arterial measurement remains the reference standard, non-invasive volume-clamp systems offer a potential alternative. We assessed the accuracy of finger-cuff-based continuous BP monitoring compared to invasive measurement in patients with pulmonary hypertension (PH). Methods: This post hoc analysis from a crossover RCT included PH patients who underwent repetitive hemodynamic assessments at rest and during exercise. The participants had simultaneous invasive BP monitoring via the radial artery and a non-invasive finger-cuff device (Finapres^® NOVA Basic). The mean blood pressure (mBP) was compared at rest, 50% of the maximal workload, and at the end of exercise using Bland–Altman and Taffé analysis. Results: In the study, 24 patients (seven female; 59 ± 14 years) contributed 385 paired mBP measurements. The invasive and non-invasive methods showed similar values at rest (96.1 ± 16.7 vs. 96.4 ± 17.2 mmHg) and during maximal exercise (106.8 ± 18.6 vs. 111.8 ± 21.6 mmHg). The overall Bland–Altman bias was 2.8 mmHg with wide limits of agreement (−39.6 to 45.3 mmHg), which remained broad across all exercise intensities. The Taffé analysis revealed a non-uniform, directionally dependent bias: the non-invasive system overestimated the mBP at low pressures and underestimated it at higher pressures. The measurement variability was substantially greater for the non-invasive method than for the invasive reference. Conclusions: In PH patients, finger-cuff-based continuous BP monitoring demonstrated acceptable group-level agreement but insufficient individual-level accuracy for clinical decision-making. Full article

In battery systems, external mechanical compression is commonly applied to pouch/prismatic cells to improve their electrical performance and mechanical integrity. However, cell clamping can hinder system heat rejection by introducing an additional thermal insulation layer. A novel battery clamping scheme was designed with reduced contact area to explore the system thermal behaviour under different cooling regimes. Experimental data obtained from battery characterisation and performance tests is analysed with a thermal-coupled equivalent circuit model to quantify changes in cell impedance and system thermal properties. By reducing the clamping area by 70%, the temperature rise of the cell was decreased by 0.5 °C in comparison to the reference condition of a cell with no clamping during a 1C discharge under natural convection. Under immersion cooling using BOT2100 dielectric liquid, the thermal benefit was amplified, resulting in temperature reductions of 0.9 °C at 1C and 4 °C at 3C. The principal conclusion of this work is that reshaping the clamping plate has the potential to reduce ohmic heating by lowering battery internal resistance, which outweighs the additional thermal resistance introduced by partial surface coverage. This novel experimental approach demonstrates the potential to improve battery thermal management through geometry-optimised cell clamping, particularly for high-power applications, and further directs the community towards cell clamping solution designed to optimise both thermal and mechanical cell performance. Full article

In karst tunnel engineering, water-filled cavities located above the tunnel crown, under the combined effects of excavation disturbance and hydraulic pressure, are prone to triggering water and mud inrush disasters. The thickness of the water-resisting rock layer is therefore a key factor controlling the stability of the surrounding rock. To address the difficulty in accurately characterizing the mechanical behavior of the crown of horseshoe-shaped tunnels using conventional circular plate or beam models, this study innovatively develops an explicit analytical model for the minimum safe thickness of the water-resisting rock layer based on clamped elliptical thin plate theory and Kirchhoff plate theory, incorporating the influence of cross-sectional geometry. Parametric sensitivity analysis indicates that both karst water pressure and tunnel crown height significantly amplify the required minimum safe thickness, whereas an increase in the tensile strength of the surrounding rock effectively reduces the thickness demand. Specifically, when the karst water pressure increases from 2.5 MPa to 4.5 MPa, the minimum safe thickness rises from 7.5 m to 10.0 m, showing an approximately linear growth trend. The analytical model is further validated through numerical simulations under different “water pressure–thickness” conditions. The results demonstrate that at the calculated recommended thickness, the surrounding rock achieves stable convergence after excavation. High tensile stress and elevated pore pressure zones are mainly concentrated near the tunnel crown, without the formation of through-going tensile failure. Engineering application indicates that the proposed model can provide a quantitative basis for the design of water-resisting rock layer thickness and the assessment of water inrush risk in karst tunnels. Full article

PDMS SlipChips are vital for precision medicine, but their performance often degrades when solutions leak or air pockets become trapped between layers. These failures stem from the inherent stickiness of PDMS and uneven surface contact, as the sliding nature of the device prevents permanent sealing. This work addresses these technical hurdles by integrating magnetic clamping with oil-infused lubrication and refined microwell geometries. A 3D-printed magnetic fixture maintains steady contact pressure during operation, while custom-made microstages provide the precise control needed to align microwells across the x–y plane. By allowing the porous PDMS to absorb silicone oil, we created a stable lubricating interface that prevents leakage and reduces friction without sacrificing mobility. We found that a microwell-to-channel width ratio of five substantially suppresses bubble formation compared with narrower designs. These enhancements ensure the generation of consistent, discrete concentration gradients and establish a reliable platform for high-throughput assays using minute sample volumes. Full article

This article presents the design and detailed characterization of a new supersonic wind tunnel at the Aerospace Laboratory for Lasers, ElectroMagnetics, and Optics of Texas A&M University, tailored for optical diagnostic development and sub-scale fundamental compressible fluid dynamics research. A Ludwieg tube tunnel architecture was selected due to its robustness, versatility, and low operational costs. The tunnel consists of a 50-foot-long driver tube constructed from modular Tri-Clamp spools, a Mach 4 nozzle with 3 in. exit diameter configured as a free jet, and a fast-acting valve with 14 ms opening time for high-duty-cycle operation. Such construction proved to be a robust, compact, and affordable solution for academic applications. Characterization methods consisted of simultaneous high-speed dot-schlieren, total and static pressure measurements, and femtosecond laser electronic excitation tagging. Average flow velocity for the first steady-state test time was measured via FLEET at (668.0 ± 5.7) m/s. The Mach number was calculated based on the angles of the attached oblique shocks formed near the 30° cone model. Calculated Mach number was repeatable from run to run and had small oscillations near the average value of 3.96 ± 0.03. Based on the simultaneously measured velocity and Mach number, the static temperature was calculated to be between (68.6 ± 0.3) K and (66.3 ± 0.3) K throughout the 400 ms test time, completely defining the thermodynamic state of the generated freestream flow. Full article

The maxillary sinus is frequently implicated in facial pain syndromes arising from infection, neoplasia, dental procedures, and, importantly, migraine, which can mimic “sinus headache” and contribute to misdiagnosis and inappropriate antibiotic use. Despite the clinical burden of chronic maxillary sinus pain, the sensory neuron subtypes that convey nociceptive and mechanosensory signals from the sinus mucosa remain incompletely defined. In this study, trigeminal ganglion (TG) neurons innervating the maxillary sinus (maxillary sinus TG neurons) were retrogradely labeled with the fluorescent dye DiD in mice and characterized using ex vivo patch-clamp electrophysiology and single-cell RT-PCR. Maxillary sinus TG neurons were found to be predominantly small-diameter, C-afferent nociceptors with electrophysiologic features including high thresholds, repetitive firing, and broad action potentials. Notably, maxillary sinus TG neurons formed a distinct molecular and functional subgroup: they expressed Nav1.9, while showing minimal Nav1.8 expression and limited overlap with Nav1.8-positive nociceptor populations. A majority of maxillary sinus TG neurons were mechanically responsive, generating mechanically activated currents with heterogeneous adaptation profiles, and a subset expressed the mechanoreceptor Piezo2. Collectively, these findings identify maxillary sinus TG neurons as a specialized population of Nav1.9-enriched C-afferent nociceptors with mechanosensitive properties, providing a mechanistic framework for pressure-evoked sinus pain. This work advances the neurobiological basis of sinus-related pain and suggests that Nav1.9 and mechanoreceptor pathways may be potential therapeutic targets for conditions in which sinus symptoms overlap with migraine and other craniofacial pain disorders. Full article

To explore the mechanism of action of CBS-derived H₂S in inducing cerebral vasodilation and activating BK_Ca channels. Sprague–Dawley (SD) rat middle cerebral arteries (MCA) were isolated from rat brains, and a pressure myography system was used to measure the effects of different concentrations of L-cysteine (L-Cys, 1 × 10^−5.5 to 1 × 10^−3.5 mol/L), a substrate for cystathionine-β-synthase (CBS)—a hydrogen sulfide (H₂S)-producing enzyme. Additionally, the effects of pretreatment with the CBS inhibitor amino-oxoacetate (AOAA, 1 mmol/L), the vascular endothelial growth factor receptor 2 inhibitor semaxanib (SU5416, 10 μmol/L), and the large-conductance calcium-activated potassium (BK_Ca) channel blocker iberiotoxin (IBTX, 100 nmol/L) were investigated to determine their impacts on CBS-derived H₂S-induced vasodilation. Acute digestion of rat vascular smooth muscle cells (VSMCs) was performed, and whole-cell patch-clamp techniques were used to measure current changes in neurons or astrocytes (ASTs), as well as acutely digested VSMCs, in the presence of L-Cys, AOAA (1 mmol/L), SU5416 (10 μmol/L), and IBTX (100 nmol/L). Additionally, neurons or ASTs were co-cultured with VSMCs to determine CBS-derived H₂S levels. Neurons or ASTs co-incubated with blood vessels and then treated with L-Cys produced H₂S, which exhibited a concentration-dependent dilatory effect on middle cerebral artery occlusion (MCA) pre-contracted with 100 nmol/L U46619 (p < 0.01). However, the addition of AOAA significantly attenuated this dilatory effect (p < 0.01). SU5416 and IBTX significantly inhibited cerebral vascular dilation (p < 0.01). H₂S produced by adding L-Cys after co-incubation of neurons or ASTs with VSMCs significantly increased BK_Ca channel current (p < 0.01). However, this effect was significantly attenuated after adding AOAA (p < 0.01). SU5416 and IBTX significantly inhibited the activation of BK_Ca channels (p < 0.01). Wild-type rat neurons or astrocytes (ASTs) were co-cultured with CSE(Cystathionine γ-lyase)-knockout vascular smooth muscle cells (VSMCs-CSE KO); the addition of L-Cys significantly increased hydrogen sulfide (H₂S) levels in the co-culture system (p < 0.01), while the addition of AOAA reduced H₂S production (p < 0.01). However, the addition of SU5416 had no statistical significance. Neurogenic H₂S, the H₂S produced by neurons and ASTs, could induce cerebral vasodilation in rats via VEGFR₂(Vascular Endothelial Growth Factor Receptor 2)-mediated activation of BK_Ca channels in the smooth muscle cells. Full article

Module- and pack-level mechanical design of lithium-ion batteries in electric vehicles is a primary driver of swelling-induced stack pressure and spatially varying ageing. Current practice remains largely empirical or data-driven and configuration-specific, limiting the ability to predict how design changes translate into local pressure heterogeneity and state-of-health (SOH) loss. This motivates a compact chemo-mechanical model that maps packaging boundary conditions to pressure, swelling, and SOH evolution with few interpretable parameters. This study introduces finite-element-ready constitutive laws that couple reversible and irreversible swelling to SOH and through-thickness pressure, covering three boundary cases reported in literature: constant pressure, thickness clamp after an initial preload, and flexible support. Parameters are identified from different published datasets, and the model is validated against independent constraint scenarios. Good quantitative agreement is shown with averaged RMSE of 1.16% for SOH and 0.16 [MPa] for pressure evolution. Variance-based sensitivity analysis shows SOH uncertainty dominated by the damage-law parameters of the proposed constitutive relationship, whereas pressure evolution is primarily controlled by irreversible swelling and the non-linear through-thickness stiffness, indicating calibration priorities for engineering design studies. The framework is intended for fast comparative analyses of individual cells under a controlled environment. Further extensions, including SOC-dependent mechanics, refined hysteresis, temperature, and C-rate variations require dedicated datasets and are left for future work. Full article

This study investigates the joint characteristics of a 60-layered copper foil stack using linear vibration ultrasonic welding for lithium-ion pouch cell applications. With increasing demand for high-capacity electric vehicle batteries, ensuring the reliability of multilayer electrode joints is essential. Experiments were conducted by varying vibrational amplitude, welding time, and clamping pressure. Weld quality was analyzed based on indentation profiles, joint strength, and failure modes. Results revealed that optimal welding energy (500–900 J) produced well-formed joints without surface cracks or tearing. Excessive welding energy (>900 J) led to material thinning and interfacial failure. The maximum T-peel peak load of 138.7 N was obtained at the 30th joining interface under 25 µm amplitude, 0.8 s welding time, and 1.5 bar clamping pressure. Interface-dependent optimum conditions were observed, reflecting thickness–direction variations in deformation and bonding within the 60-layer stack. Indentation length and depth correlated linearly with welding energy. Failure modes transitioned from no adhesion to tearing and button-pull types. The findings provide guidelines for optimizing welding parameters for high-quality multilayer foil joints in battery manufacturing. Full article

A demountable connection is necessary to enable quick and easy replacement of high-temperature superconducting (HTS) tape samples during cryogenic (77 K) testing, particularly when investigating their application in superconducting fault current limiters (SFCLs). Testing HTS tapes for application in SFCLs involves inducing their transition from the superconducting state to the resistive state, which can result in sample damage. The contact resistance of the HTS tape to the current lead depends on the area and on the uniform pressure. Stress distribution in screwed connections with two, four and six screws was analysed using a solid model to compare them and achieve the uniform contact essential for minimising contact resistance in cryogenic conditions. The analysis indicated a solution that provides the most uniform pressure distribution across the HTS tape surface. This solution was utilised in subsequent calculations of thermal shrinkage, and for the determination of the optimal disc spring stack configuration. It is imperative that the compensating disc springs maintain the requisite pressure of the copper block on the tape across the entire operational temperature range (room to cryogenic). Furthermore, the disc springs must provide adequate stroke to compensate for the thermal shrinkage of a copper block and an aluminium clamp. Full article

Bolted connections are critical in deep-sea engineering, yet classical theories (such as VDI 2230) implicitly assume atmospheric pressure conditions, neglecting the volume contraction of components due to hydrostatic pressure. This fundamental flaw hinders accurate prediction of preload retention—especially when bolts and clamped components exhibit differential compressibility (a common scenario in practical applications). To bridge this scientific gap, this paper establishes the first analytical model for bolt preload under pressure-induced volumetric contraction based on deformation coordination relations. The derived closed-form expressions explicitly quantify residual preload as a function of deep-sea ambient pressure, component bulk modulus, and geometric parameters. Model predictions closely match finite element calculations, showing that stainless steel bolts clamping aluminum alloys under 110 MPa pressure can experience up to a 40% preload reduction. This theoretical framework extends classical bolt connection mechanics to high-pressure environments, providing a scientific basis for optimizing deep-sea connection designs through material matching and dimensional control to effectively mitigate pressure-induced preload loss. Full article