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Acoustic sensors are able to capture more incident energy if their acoustic impedance closely matches the acoustic impedance of the medium being probed, such as skin or wood. Controlling the acoustic impedance of polymers can be achieved by selecting materials with appropriate densities and stiffnesses as well as adding ceramic nanoparticles. This study follows a statistical methodology to examine the impact of polymer type and nanoparticle addition on the fabrication of acoustic sensors with desired acoustic impedances in the range of 1-2.2 MRayls. The proposed method using a design of experiments approach measures sensors with diaphragms of varying impedances when excited with acoustic vibrations traveling through wood, gelatin, and plastic. The sensor diaphragm is subsequently optimized for body sound monitoring, and the sensor's improved body sound coherence and airborne noise rejection are evaluated on an acoustic phantom in simulated noise environments and compared to electronic stethoscopes with onboard noise cancellation. The impedance-matched sensor demonstrates high sensitivity to body sounds, low sensitivity to airborne sound, a frequency response comparable to two state-of-the-art electronic stethoscopes, and the ability to capture lung and heart sounds from a real subject. Due to its small size, use of flexible materials, and rejection of airborne noise, the sensor provides an improved solution for wearable body sound monitoring, as well as sensing from other mediums with acoustic impedances in the range of 1-2.2 MRayls, such as water and wood.

Chest auscultation is a widely used clinical tool for respiratory disease detection. The stethoscope has undergone a number of transformative enhancements since its invention, including the introduction of electronic systems in the last two decades. Nevertheless, stethoscopes remain riddled with a number of issues that limit their signal quality and diagnostic capability, rendering both traditional and electronic stethoscopes unusable in noisy or non-traditional environments (e.g., emergency rooms, rural clinics, ambulatory vehicles). This work outlines the design and validation of an advanced electronic stethoscope that dramatically reduces external noise contamination through hardware redesign and real-time, dynamic signal processing. The proposed system takes advantage of an acoustic sensor array, an external facing microphone, and on-board processing to perform adaptive noise suppression. The proposed system is objectively compared to six commercially-available acoustic and electronic devices in varying levels of simulated noisy clinical settings and quantified using two metrics that reflect perceptual audibility and statistical similarity, normalized covariance measure (NCM) and magnitude squared coherence (MSC). The analyses highlight the major limitations of current stethoscopes and the significant improvements the proposed system makes in challenging settings by minimizing both distortion of lung sounds and contamination by ambient noise.

Background: Whether digitally recorded lung sounds are associated with radiographic pneumonia or clinical outcomes among children in low-income and middle-income countries is unknown. We sought to address these knowledge gaps., Methods: We enrolled 1 to 59monthold children hospitalized with pneumonia at eight African and Asian Pneumonia Etiology Research for Child Health sites in six countries, recorded digital stethoscope lung sounds, obtained chest radiographs, and collected clinical outcomes. Recordings were processed and classified into binary categories positive or negative for adventitial lung sounds. Listening and reading panels classified recordings and radiographs. Recording classification associations with chest radiographs with World Health Organization (WHO)-defined primary endpoint pneumonia (radiographic pneumonia) or mortality were evaluated. We also examined case fatality among risk strata., Results: Among children without WHO danger signs, wheezing (without crackles) had a lower adjusted odds ratio (aOR) for radiographic pneumonia (0.35, 95% confidence interval (CI): 0.15, 0.82), compared to children with normal recordings. Neither crackle only (no wheeze) (aOR: 2.13, 95% CI: 0.91, 4.96) or any wheeze (with or without crackle) (aOR: 0.63, 95% CI: 0.34, 1.15) were associated with radiographic pneumonia. Among children with WHO danger signs no lung recording classification was independently associated with radiographic pneumonia, although trends toward greater odds of radiographic pneumonia were observed among children classified with crackle only (no wheeze) or any wheeze (with or without crackle). Among children without WHO danger signs, those with recorded wheezing had a lower case fatality than those without wheezing (3.8% vs. 9.1%, p = .03)., Conclusions: Among lower risk children without WHO danger signs digitally recorded wheezing is associated with a lower odds for radiographic pneumonia and with lower mortality. Although further research is needed, these data indicate that with further development digital auscultation may eventually contribute to child pneumonia care., (© 2020 The Authors. Pediatric Pulmonology published by Wiley Periodicals LLC.)

We used manually spawned, field-deployed embryos of a common marine fish species, Pacific herring (Clupea pallasii), to evaluate accumulation of polycyclic aromatic hydrocarbons (PAHs) associated with an incomplete creosote-treated piling (CTP) removal project. Embryos near undisturbed 100-year-old CTPs (before removal) accumulated higher PAHs and exhibited higher cyp1a gene expression than embryos from reference areas. Embryos incubated close to CTP debris after CTP removal showed PAHs 90 times higher than reference areas up to a year after CTP removal. cyp1a fold-induction correlated with total embryo PAHs in all three years. Patterns of individual PAH chemicals differed slightly between embryos, wood sampled from CTPs, and passive samplers. This study illustrates the importance of using appropriate techniques and procedures to remove CTPs in aquatic environments to prevent release of toxic chemicals. Of particular concern is that incomplete CTP removal could expose sensitive life stages of fishes to chemicals that may reduce their survival., (Published by Elsevier Ltd.)

Piezoelectric composite (p-NC) made of a polymeric matrix and piezoelectric nanoparticles with conductive additives is an attractive material for many applications. As the matrix of p-NC is made of viscoelastic materials, both elastic and viscous characteristics of the matrix are expected to contribute to the piezoelectric response of p-NC. However, there is limited understanding of how viscoelasticity influences the piezoelectric performance of p-NC. Here we combined analytical and numerical analyses with experimental studies to investigate effects of viscoelasticity on piezoelectric performance of p-NC. The viscoelastic properties of synthesized p-NCs were controlled by changing the ratio between monomer and cross-linker of the polymer matrix. We found good agreement between our analytical models and experimental results for both quasi-static and dynamic loadings. It is found that, under quasi-static loading conditions, the piezoelectric coefficients (d 33 ) of the specimen with the lowest Young's modulus (∼0.45 MPa at 5% strain) were ∼120 pC N -1 , while the one with the highest Young's modulus (∼1.3 MPa at 5% strain) were ∼62 pC N -1 . The results suggest that softer matrices enhance the energy harvesting performance because they can result in larger deformation for a given load. Moreover, from our theoretical analysis and experiments under dynamic loading conditions, we found the viscous modulus of a matrix is also important for piezoelectric performance. For instance, at 40 Hz and 50 Hz the storage moduli of the softest specimen were ∼0.625 MPa and ∼0.485 MPa, while the loss moduli were ∼0.108 MPa and ∼0.151 MPa, respectively. As piezocomposites with less viscous loss can transfer mechanical energy to piezoelectric particles more efficiently, the dynamic piezoelectric coefficient (d' 33 ) measured at 40 Hz (∼53 pC N -1 ) was larger than that at 50 Hz (∼47 pC N -1 ) though it has a larger storage modulus. As an application of our findings, we fabricated 3D piezo-shells with different viscoelastic properties and compared the charging time. The results showed a good agreement with the predicted trend that the composition with the smallest elastic and viscous moduli showed the fastest charging rate. Our findings can open new opportunities for optimizing the performance of polymer-based multifunctional materials by harnessing viscoelasticity.

We modeled temporal trends in polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dichlorodiphenyltrichloroethane and its metabolites (DDTs) in two indicator fish species representing benthic and pelagic habitats in Puget Sound, Washington, USA. English sole (Parophrys vetulus, benthic) index sites and larger-scale Pacific herring (Clupea pallasii, pelagic) foraging areas represented a wide range of possible contamination conditions, with sampling locations situated adjacent to watersheds exhibiting high, medium and low development. Consistency in analytical data throughout the study was maintained by either calculating method-bias-correction factors on paired samples as methods evolved or by analyzing older archived samples by current methods. PCBs declined moderately in two herring stocks from a low-development basin (2.3 and 4.0% annual rate of decline) and showed no change in the highly developed and moderately developed basins during a 16- to 21-year period. PCBs increased in English sole from four of ten sites (2.9-7.1%), and the remaining six exhibited no significant change. PBDEs and DDTs declined significantly in all herring stocks (4.2-8.1%), although analytical challenges warrant caution in interpreting DDT results. PBDEs declined in English sole from two high-development and one low-development site (3.7-7.2%) and remained unchanged in the remaining seven. DDTs increased in English sole from one high-development site (Tacoma City Waterway) and declined in two high-development and one low development site. As with herring, analytical challenges warrant caution in interpreting the English sole DDT results. It is likely that source controls and mitigation efforts have contributed to the declines in PBDEs and DDTs overall, whereas PCBs appear to have persisted, especially in the pelagic food web, despite bans in PCB production and use.

Introduction: Paediatric lung sound recordings can be systematically assessed, but methodological feasibility and validity is unknown, especially from developing countries. We examined the performance of acoustically interpreting recorded paediatric lung sounds and compared sound characteristics between cases and controls., Methods: Pneumonia Etiology Research for Child Health staff in six African and Asian sites recorded lung sounds with a digital stethoscope in cases and controls. Cases aged 1-59 months had WHO severe or very severe pneumonia; age-matched community controls did not. A listening panel assigned examination results of normal, crackle, wheeze, crackle and wheeze or uninterpretable, with adjudication of discordant interpretations. Classifications were recategorised into any crackle, any wheeze or abnormal (any crackle or wheeze) and primary listener agreement (first two listeners) was analysed among interpretable examinations using the prevalence-adjusted, bias-adjusted kappa (PABAK). We examined predictors of disagreement with logistic regression and compared case and control lung sounds with descriptive statistics., Results: Primary listeners considered 89.5% of 792 case and 92.4% of 301 control recordings interpretable. Among interpretable recordings, listeners agreed on the presence or absence of any abnormality in 74.9% (PABAK 0.50) of cases and 69.8% (PABAK 0.40) of controls, presence/absence of crackles in 70.6% (PABAK 0.41) of cases and 82.4% (PABAK 0.65) of controls and presence/absence of wheeze in 72.6% (PABAK 0.45) of cases and 73.8% (PABAK 0.48) of controls. Controls, tachypnoea, >3 uninterpretable chest positions, crying, upper airway noises and study site predicted listener disagreement. Among all interpretable examinations, 38.0% of cases and 84.9% of controls were normal (p<0.0001); wheezing was the most common sound (49.9%) in cases., Conclusions: Listening panel and case-control data suggests our methodology is feasible, likely valid and that small airway inflammation is common in WHO pneumonia. Digital auscultation may be an important future pneumonia diagnostic in developing countries., Competing Interests: Competing interests: None declared.

Pacific herring embryos spawned in nearshore habitats may be exposed to toxic contaminants as they develop, from exogenous sources in spawning habitats and from maternal transfer. Determining baseline concentrations of these toxic contaminants is important for evaluating the health of this species, especially during this sensitive life stage. In this study we compared concentrations of polycyclic aromatic hydrocarbons, or PAHs, in naturally spawned herring embryos from five spawning areas across Puget Sound. The summed values of 31 PAH analytes (Σ31PAH) in early- to late-stage development embryos ranged from 1.1 to 140 ng/g, wet weight. Σ31PAH concentrations increased with development time in embryos from one spawning area where the greatest concentrations were observed, and the relative abundance of PAH chemicals in late-stage embryos was similar to those in nearby sediments, suggesting accumulation from local environmental sources. PAHs in both sediments and late-stage embryos appeared to exhibit a pyrogenic pattern. Although maternal transfer of PAHs appeared to be a negligible source to embryos in spawning areas with the greatest embryo PAH concentrations, maternal transfer may have been the dominant source in embryos from spawning areas where the lowest levels of embryo-PAHs occurred. Chronic embryo mortality has been reported in spawning habitats where we observed the greatest concentration of PAHs in embryos, and necrotic tissue in herring embryos from one such location was similar in description to phototoxic PAH necrosis reported elsewhere for embryonic zebrafish., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Velocity and pressure microphones composed of piezoelectric poly(γ-benzyl-α,L-glutamate) (PBLG) nanofibers were produced by adhering a single layer of PBLG film to a Mylar diaphragm. The device exhibited a sensitivity of -60 dBV/Pa in air, and both pressure and velocity response showed a broad frequency response that was primarily controlled by the stiffness of the supporting diaphragm. The pressure microphone response was ±3 dB between 200 Hz and 4 kHz when measured in a semi-anechoic chamber. Thermal stability, easy fabrication, and simple design make this single element transducer ideal for various applications including those for underwater and high temperature use.