Search Results (715)

The miniaturization of medical ultrasound imaging transducers is currently limited by the thick backing layers required to dissipate backward acoustic energy. To address this, a novel hybrid composite backing material was developed by interpenetrating a three-dimensional open-cell nickel foam skeleton with a traditional tungsten-powder/epoxy-resin matrix. Two groups of composite samples with varying pores per inch (PPI) were fabricated, and their acoustic properties were systematically characterized. Experimental results indicated that the 100 PPI composite achieved macroscopic acoustic attenuation coefficients of 62.6 dB/cm at 5 MHz and 84.2 dB/cm at 7.5 MHz. These values are roughly three times higher than conventional backing materials, while maintaining a suitable acoustic impedance of 10.81 MRayl. A 5 MHz transducer utilizing a 5.0 mm layer of this proposed backing achieved a −60 dB two-way pulse-echo insertion loss, effectively eliminating backside interference with performance comparable to a 16.5 mm conventional backing. This structural strategy successfully reduces the required backing axial dimension by over 60% without compromising transducer bandwidth, offering a viable material solution for miniaturized ultrasonic transducers. Full article

A novel broadband ultrasonic transducer design based on a non-uniform-thickness double-layer piezoelectric structure and a variable-thickness matching layer is proposed to overcome the limitations of conventional thickness-mode piezoelectric ultrasonic transducers, such as weak even-order harmonic responses and restricted bandwidth. The implementation of a non-uniform-thickness double-layer piezoelectric structure enables the simultaneous excitation and reception of ultrasonic signals containing both fundamental and second-harmonic frequencies. Furthermore, through the integration of variable-thickness matching layers with a backing material of non-uniform acoustic impedance, the dual resonant frequency responses are effectively merged into a broad bandwidth. The broadband transducer prototype is manufactured and characterized through electrical input impedance, time-domain pulse-echo signals, and corresponding frequency spectrum. Experimental results indicate a center frequency of 411.5 kHz, with dual resonant peaks observed near 298.6 kHz and 585.6 kHz, achieving a −6 dB relative bandwidth of 116%. The findings demonstrate that the self-developed broadband transducer is capable of effectively generating and receiving broadband signals containing both fundamental and second-harmonic components, thereby offering a new design strategy for broadband piezoelectric transducers. Full article

Tumor oxygenation is a key determinant of cancer biology and treatment response, correlating with angiogenesis, recurrence, and malignant progression. Hypoxia is a defining feature of glioblastoma (GBM) and adult diffuse gliomas, generating low-oxygen niches that promote invasion, stem-like states, immune suppression, and resistance to radiotherapy and temozolomide, contributing to poor outcomes. Measuring tissue partial pressure of oxygen (pO₂) and mapping its spatial heterogeneity can, therefore, inform mechanistic understanding and therapeutic development, including hypoxia-activated prodrugs, hypoxia-responsive gene therapy, and optimized radiotherapy planning. Although direct pO₂ assessment is challenging, invasive probes and multimodal imaging can characterize regional hypoxia pre-operatively, support patient stratification, monitor treatment effects, and improve outcome prediction. This review summarizes oxygen dynamics in GBM; analyzes causes of hypoxia (rapid growth outpacing supply, diffusion-limited hypoxia, and abnormal/chaotic vasculature); compares methods to quantify oxygenation from direct measurements to noninvasive imaging surrogates; and evaluates preclinical and clinical strategies that target hypoxia to enhance standard therapy, including barriers to translation. We further integrate oxygenation with cell signaling and redox biology: oxygen gradients are transduced via hypoxia-inducible factor programs and redox-sensitive pathways (NRF2/KEAP1, NOX-derived ROS, nitric oxide/S-nitrosylation, and sulfur metabolic routes), shaping mesenchymal-like transitions and cell-death programs such as ferroptosis. Framing oxygenation as both a microenvironmental and redox-signaling variable positions oxygen imaging as an entry point to biomarker-guided therapies that exploit oxidative vulnerabilities. Full article

Chroococcidiopsis sp. was isolated from the endolithic habitat of the Atacama Desert (northern Chile), one of the most challenging-to-life polyextreme environments on Earth. The photosynthetic machinery of microorganisms inhabiting this environment is supposed to be highly adapted to cope with the intense solar radiation of the area. Thus, PAR-red light ranging from 100 to 900 µmol photon·m⁻²·s⁻¹ has been investigated as a strategy to enhance culture productivity and stimulate the synthesis of bioactive molecules in Chroococcidiopsis sp. A control culture was maintained under white light at 100 µmol photon·m⁻²·s⁻¹. The results revealed that red light was utilized more efficiently than white light of similar irradiance, and its modulation enhanced both growth and photosynthetic activity of the cyanobacterium. Furthermore, Chroococcidiopsis sp. appeared to activate mechanisms to mitigate photooxidative stress produced by excess light energy. Specifically, increasing light irradiance induced photoacclimation responses, characterized by a decrease in chlorophyll content and a concomitant increase in carotenoid accumulation, likely aimed at reducing photon flux transduced to photosynthesis. Additionally, scytonemin synthesis was enhanced under high irradiances, contributing to dissipating excess light energy. Overall, this study demonstrates that modulation of red-light irradiance effectively improves the growth of Chroococcidiopsis sp. while promoting the accumulation of antioxidant compounds—primarily carotenoids and, to a lesser extent, scytonemin. Full article

A capacitive micromachined ultrasonic transducer (CMUT) was engineered and functionalized with either zeolitic imidazolate framework-8 (ZIF-8) dispersed in an AZ1512HS photoresist matrix or with graphene oxide (GOx) to operate as a gravimetric sensor for organic vapors. The sensor response was investigated under controlled humidity conditions during pulsed exposure to acetone, ethyl methyl ketone, isopropanol, kerosene, and diesel vapors. The impedance of the device was monitored by observing and tracking the resonance frequency shift as well as the resistance maximum shift, giving us the possibility to track two response parameters simultaneously. Different combinations of shifts in the sensor resonance frequency and the resistance maximum values were observed for the ZIF-8 functionalized device when exposed to the selected vapors, ranging from 12.4 kHz for ethyl methyl ketone to 2.4 kHz for diesel, and from 580 Ω for acetone to 20 Ω for isopropanol. Sensors functionalized with GOx did not demonstrate any significant response to either ethyl methyl ketone or isopropanol in the frequency domain. GOx-functionalized sensors were used for relative humidity monitoring in test gases. Besides the conventional response of the produced gravimetric sensing system, we also observed a strong relationship between the humidity of the gas mixture and the strength of the interaction of target gases with the functional film of the sensor. The results highlight the multidimensional nature of the sensor response and demonstrate how humidity influences the interaction between vapor molecules and the functional coating. This paper focuses on the characterization of the coupled behavior of resonance frequency and resistance shifts under controlled operating conditions. The presented experimental setup provides a basis for future concentration-dependent investigations and functional material comparisons in CMUT-based gravimetric sensing systems and provides a necessary foundation for accurate interpretation of future concentration-resolved measurements. Full article

Creating a dependable approach for identifying both the mass of a shuttle car and how material is distributed in it removes the need for equipment operators to manually engage the flight chain. The quantification of environmental and installation conditions and the extent of influence considering their combined contribution towards inaccurate or exclusive measurements are to that degree limited. This experimental study investigated how two different strain transducers—installed in a force-shunt configuration—respond to thermo-mechanical loads when used to determine load distribution and position. Initial observations indicated that thermal effects at the installation site contributed to measurement inaccuracies or exclusive readings. The investigation quantified the impact of environmental and installation variables on measurement accuracy and found this influence to be indirectly linked to the mechanical properties of the substrate to which the strain transducers were mounted. Mounting bolt torque was determined to exert a negligible effect on strain measurement accuracy for the custom-built strain transducers. Nonetheless, both transducers failed to consistently return to the selected baseline at the start of experiments since thermal dependence persisted at the balanced state following the first cycle of loading. The research indicated that the custom-built force-shunt strain transducers are an effective means for mapping the profile and location of coal in shuttle cars, provided that the systems are subjected to continuous and cyclic rebalancing to maintain accuracy. Full article

Multifrequency operation in micromachined ultrasonic transducers, enabled by targeted excitation of specific vibrational modes, has emerged as an attractive approach for achieving tunable performance and configurability, well-suited for advanced ultrasound imaging and therapeutic applications. This paper presents a dual-electrode rectangular piezoelectric micromachined ultrasonic transducer (PMUT) designed for efficient dual-frequency operation through mode-selective actuation. The proposed architecture employs segmented electrodes that are spatially aligned with the strain distributions of two distinct flexural modes, enabling selective excitation of Mode 1 (fundamental) and Mode 3 (higher order) through appropriate electrode actuation. Finite element simulations and impedance analysis were used to guide the electrode configuration and validate the mode-selective behavior. The dual-mode PMUT was fabricated alongside a conventional single-electrode PMUT using identical membrane dimensions and material stack for direct comparison. Comprehensive electrical and underwater acoustic characterization confirmed that the conventional PMUT is limited to single-frequency operation at the fundamental resonance. In contrast, the proposed design achieved a substantial improvement in higher-order performance, with a threefold increase in acoustic pressure at Mode 3 compared to the conventional device. These results demonstrate that mode-aligned electrode segmentation enables efficient dual-mode operation without added fabrication complexity, making the design highly suitable for multifrequency ultrasonic applications such as biomedical imaging and sensing. Full article

The failure of impedance matching between the ultrasonic power supply and the transducer can degrade machining quality, decrease machining efficiency, and reduce tool life. To enhance the detection efficiency of impedance matching status in ultrasonic machining systems, an impedance matching detection method based on the Voltage Standing Wave Ratio (VSWR) is proposed. First, by constructing a fitting model for the forward and reverse voltage and power of ultrasonic power supply, the relationship between VSWR and voltage is determined. Subsequently, a correlation model between the VSWR and tool tip amplitude, which reflects the working state of the ultrasonic system, is established. And the range of VSWR for optimal performance of system impedance matching is obtained by means of the model. Finally, the detection effectiveness of this method is verified through experiments on tool tip output amplitude under varying working conditions, and a comparison is made between this method and the phase method. The results indicate that using VSWR as a detection parameter to characterize impedance matching yields measurement values within 7% of the theoretical values. These results confirm the evaluation interval for a good working state of the system. Furthermore, experiments under varying force loads and temperatures demonstrate the reliability of the VSWR-based characterization. Compared to the traditional phase method, this approach reduces the cost of impedance matching performance detection and meets the requirements for impedance matching status detection during ultrasonic machining. Full article

Ultrasound imaging is a crucial tool for guiding radiation therapy, particularly for cancers such as pancreatic cancer, where tumors exhibit respiration-induced motion. While flexible ultrasound transducers offer improved anatomical conformity and reduced compression-induced distortion compared to rigid probes, their variable geometry presents significant challenges for conventional beamforming. In this study, we investigate a deep learning-based beamforming framework that directly predicts delayed RF data from raw RF input, bypassing explicit transducer shape estimation and traditional delay-and-sum computations. Building upon an artificial curvature simulation strategy, we systematically analyze the impact of curvature-induced variation and inherent RF noise on model performance and generalizability. We further introduce frequency-domain analysis to quantify RF-level signal variation that may not be apparent in spatial-domain image comparisons. Our results demonstrate that although noise-augmented training improves prediction consistency, reconstruction performance remains limited under the current prototype noise conditions. These findings highlight the importance of RF data diversity and noise characterization in developing clinically robust deep learning beamformers for flexible transducer-based ultrasound-guided radiation therapy. Full article

Histone deacetylase 6 (HDAC6), a member of the class IIb HDAC family, plays a crucial role in epigenetic regulation and cytoskeletal dynamics, while participating in host anti-infective immune responses. However, its precise functions and mechanisms during Chlamydia muridarum (C. muridarum) infection remain incompletely defined. Our study demonstrated that C. muridarum respiratory infection upregulates HDAC6 expression at the infection site and in immune organs. Comparative analysis of wild-type (WT) and HDAC6-deficient (HDAC6^−/−) mice in this infection model revealed that HDAC6 deficiency exacerbates disease progression, including significant weight loss, severe pulmonary inflammation, and impaired C. muridarum clearance. Relative to WT mice, HDAC6^−/− mice exhibited elevated Signal Transducer and Activator of Transcription 6 (Stat6) and GATA Binding Protein 3 (Gata3) mRNA expression, enhanced pathological Th2 responses with increased IL-4 secretion, and no significant differences in protective Th1 or Th17 responses following C. muridarum infection. Concurrently, these mice displayed enhanced M2 macrophage polarization, as evidenced by upregulated CD206 and Arg-1 expression, whereas M1 marker expression remained unchanged. The vitro studies confirmed that HDAC6^−/− bone marrow-derived macrophages (BMDMs) promote M2 polarization, characterized by increased Arg-1, IL-10, and TGF-β production, and further co-culture experiments showed that C. muridarum -stimulated HDAC6^−/− BMDMs drive Th2 differentiation. These findings elucidate the critical role of HDAC6 in regulating Th2-M2 immune responses during C. muridarum respiratory infection and suggest targeted modulation of HDAC6 as a novel therapeutic strategy for chlamydial respiratory infection. Full article

Objective: This prospective study investigated the use of H-scan ultrasound (US) imaging as a novel component of a multiparametric radiomic analysis framework for characterizing human breast cancer response to neoadjuvant chemotherapy (NAC) before and early after treatment initiation. Methods: Thirty breast cancer patients scheduled for NAC were scanned using a clinical US system (Logiq E9, GE HealthCare) equipped with a 9L-D linear array transducer. Radiofrequency (RF) data was obtained at baseline (pre-NAC) and after 10% and 30% of the complete dose of chemotherapy. The RF data was analyzed by a bank of 256 frequency-shifted bandpass filters to form H-scan US frequency images. Grayscale texture features were extracted from both B-scan and H-scan US images. In addition, US attenuation coefficient and speckle statistics based on the Nakagami and Burr distributions were estimated from the RF data. Data classification of tumor and peri-tumoral regions was performed using a novel three-dimensional (3D) score map based on support vector machine (SVM) modeling. Unlike conventional classifiers that report only a single prediction score, a 3D score map provides a visual representation of the classifier decision space, enabling interpretation of class separation and treatment-induced shifts in multiparametric US measurements. Results: The dataset was split into 10 disjoint partitions (90% training, 10% testing) to compute area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy measures. Actual patient response to NAC was assessed at surgery and categorized as either pathologic complete response (pCR) or non-pCR. Multiparametric US and data classification results at pre-NAC found AUC values of 0.78 after using only tumor information (p < 0.01), which increased to 0.81 with inclusion of peri-tumoral information (p < 0.01). Significant differences in multiparametric US measures from both cancer response types was found after integration of patient data collected at 10% completion of the NAC regimen (i.e., first NAC cycle), yielding an improved AUC of 0.86 (p < 0.001). Conclusions: Multiparametric US imaging with radiomic features from both the tumor and peri-tumoral regions is a promising noninvasive approach for monitoring early breast cancer response to NAC. Full article

Chapare virus (CHAPV) is an Arenaviridae family member and causative agent of Chapare hemorrhagic fever (CHHF). Endemic to Bolivia, CHAPV was found to be the cause of several outbreaks of CHHF in Bolivia in 2003 and 2019 with high case-fatality rates and instances of human-to-human transmission. The pathogenesis of CHAPV infection is poorly understood, and no vaccines or antivirals are available, in part due to a dearth of available animal models. Mice lacking signal transducer and activator of transcription 1 (STAT1^-/-) have been shown to succumb to infection by related arenaviruses, including Machupo virus, and were investigated for their susceptibility to CHAPV infection. Challenge with CHAPV resulted in partial lethality in STAT1^-/- mice with a biphasic disease course characterized by initial viral load and pathology in the spleen and liver followed by inflammation and high viral titers in the brain and spinal cord that immediately preceded mortality. Adaptation in the brains of STAT1^-/- mice resulted in a fully lethal mouse-adapted CHAPV variant, with a similar biphasic disease course, but virus in tissues was detected more proximal to challenge. The result of this study is a lethal small-animal rodent model for CHAPV that recapitulates many aspects of human CHAPV disease. Full article

Sepsis is characterized by dysregulated immune responses induced by damage-associated molecular patterns, such as extracellular cold-inducible RNA-binding protein (eCIRP), that frequently lead to acute lung injury (ALI) and high mortality. Recently, a subset of CD4⁺ T cells possessing both T helper 1 (Th1) and regulatory T cell (Treg) phenotypes, termed Th1-Treg cells, has been identified; however, their function in sepsis remains unknown. In this study, we investigated the dynamics, induction mechanisms, and functional roles of Th1-Treg cells in the development of sepsis-induced ALI. Polymicrobial sepsis was induced in mice using cecal ligation and puncture. In vivo, Th1-Treg cell accumulation in the lungs was analyzed in WT and CIRP^−/− mice following sepsis. In vitro, isolated CD4⁺ T cells from WT and TLR4^−/− mice were treated with eCIRP to evaluate Th1-Treg cell differentiation and downstream signaling pathways. STAT1 and STAT5 activation were evaluated, and pharmacological inhibitors were used to assess their involvement. Adoptive transfer of Th1-Treg cells was conducted to determine their functional impact on ALI and mortality in septic mice. We observed a significant accumulation of Th1-Treg cells in the lungs of WT septic mice compared to sham mice. eCIRP drove the induction of Th1-Treg cells in vitro, and CIRP^−/− mice exhibited decreased Th1-Treg cell accumulation in the lungs compared to WT mice after sepsis. In parallel to Th1-Treg cell induction, eCIRP activated signal transducer and activator of transcription, STAT1 and STAT5. Both the induction of Th1-Treg cells and the activation of STAT1/5 proteins were significantly attenuated in TLR4^−/− mice. Furthermore, pharmacological inhibition of STAT1/5 signaling significantly reduced eCIRP-induced Th1-Treg cell differentiation. Intriguingly, adoptive transfer of Th1-Treg cells significantly exacerbated ALI, resulting in increased mortality in sepsis. Our findings indicate Th1-Treg cells induced by the eCIRP–TLR4–STAT1/5 axis aggravate ALI, worsening mortality in sepsis. Targeting these pathogenic cells potentially alleviates sepsis-induced ALI. Full article

Transducers for ultrasonic nondestructive evaluation of materials in harsh environments are needed to manage safe operations in a number of industrial applications including power generation, propulsion, and material and chemical processing. Bismuth titanate has a reasonably high Curie temperature and transduces electrical energy into elastic waves and vice versa. Herein, a slurry containing bismuth titanate powder is air-sprayed onto stainless steel substrates, functionalized, and characterized in terms of coating thickness, center frequency and bandwidth, and signal-to-noise ratio. Coatings 40– 70 μm thick had a center frequency of approximately 7 MHz and a broad frequency response range of 3–20 MHz. Transducers were thermally aged at 375 °C for seven days to assess their temperature tolerance. Post-aging analysis revealed a resonance frequency increase, thickness reduction, and microstructural changes, accompanied by a decrease in signal amplitude. Despite these changes, the aged transducers remained operational with good signal-to-noise ratio. Thermal cycling experiments showed that the response of pristine transducers is changed by cycling to 250 °C, while thermally aged transducers exhibited stable ultrasonic performance. Additional experiments on transducers pre-conditioned at 400 °C demonstrated improved thermal resilience after thermal aging at 350 °C. These field deployable air-sprayed BIT transducers are promising candidates for high-temperature NDE applications. Full article

The construction sector is a major user of natural materials and a key contributor to global carbon emissions. To tackle these environmental challenges, the use of recycled products has become increasingly important in modern engineering. Cellular glass aggregate (CGA), made from recycled glass, is a material with potential as a sustainable alternative to natural aggregates. This study characterizes the cyclic behavior of CGA using a large-scale triaxial apparatus, focusing on seismic-relevant properties such as the damping ratio and Young’s modulus. Local displacement transducers (LDTs) were implemented to improve measurement at small strains. The results show that CGA exhibits strain-dependent stiffness and damping behavior comparable to natural aggregates at moderate strains (10⁻⁴–10⁻³). The Young’s modulus ranges from approximately 300 to 600 MPa, while damping ratios remain at approximately 2–3% for low values of strains (10⁻⁵). As strain increases to moderate levels (10⁻⁴–10⁻³), the Young’s modulus decreases to approximately 80–250 MPa, accompanied by an increase in damping ratio to approximately 4–6%. At higher strain levels ≥ 10⁻³, the Young’s modulus further reduces to approximately 40–80 MPa, while damping ratios increase to approximately 7–10%. These stiffness degradation and damping trends fall within the ranges reported for sands and gravelly soils in the literature, indicating that CGA can reproduce the cyclic mechanical behavior of natural aggregates under well-defined strain conditions. Full article