Ventilated acoustic metasurface with low-frequency sound insulation.

A ventilated acoustic metasurface consisting of a membrane covered with a combination of different depth sub-chambers is proposed. It can achieve at least a 5 dB sound insulation acoustic performance in the wide frequency range from 100 to 1700 Hz, in particular a 10 dB noise reduction in the range from 100 to 200 Hz and from 437.4 to 1700 Hz, which can therefore cover the low-frequency range of the environmental noise. The physical mechanism of membrane-acoustic coupling for noise reduction in the low-frequency range is further explored.

Design and Protocol for Beijing Hospital Takayasu Arteritis (BeTA) Biobank.

BACKGROUND: Although hundreds of studies have been conducted, our understanding of the pathogenesis, indications for surgical intervention, and disease markers of Takayasu arteritis (TAK) are still limited. Collection of biological specimens, clinical data and imaging data will facilitate translational research and clinical studies. In this study, we aim to introduce the design and protocol for the Beijing Hospital Takayasu Arteritis (BeTA) Biobank. METHODS: Based in the Department of Vascular Surgery of Beijing Hospital and Beijing Hospital Clinical Biological Sample Management Center, the BeTA Biobank is composed of clinical data and sample data from patients with TAK requiring surgical treatment. All clinical data of participants are collected, including demographic characteristics, laboratory tests, imaging results, operation information, perioperative complications, follow-up data, etc. Both blood samples including plasma, serum and cells, and vascular tissues or perivascular adipose tissue are collected and stored. These samples will promote the establishment of a multiomic database for TAK and help to identify disease markers and to explore potential targets for specific future drugs for TAK.

[Effects of Pollution Control of Xiaoqing River on Environment Factors and Phytoplankton Community in the Laizhou Bay].

The spatial distribution of environmental factors, chlorophyll a (Chla), phytoplankton abundance, and community structure in the Laizhou Bay were investigated in August 2018 (wet season after pollution control) to clarify the effects of the pollution control of the Xiaoqing River, which is a major source of pollution, on environmental factors and phytoplankton community structure in this area. The results showed that the environmental factors changed significantly after pollution control of the Xiaoqing River. The concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic silicon (DSi), NO3-, and NO2- decreased significantly, with values only 40.1% to 60.4% of those from the same period of in 2017 (the nearest year before the pollution control), whereas dissolved inorganic phosphorus (DIP) and NH4 increased by 2.5 and 1.4 times that of their concentrations in 2017. The spatial distribution of environmental factors changed significantly, with the nutrient concentrations around the Xiaoqing River estuary noticeably decreasing. The abundance of phytoplankton cells was 21.5×106 cell·m-3, which was close to the results of a previous study, whereas the ρ(Chla) was 2.43 µg·L-1, which decreased obviously. Both microscopic analysis and pigment taxonomy suggested that phytoplankton community structure in the Laizhou Bay changed clearly, with the dominant community shifting from diatoms alone to the co-dominance of diatoms and cyanobacteria. Chaetoceros curvisetus, Skeletonema costatum, and Cerataulina pelagica, which were commonly observed in the Laizhou Bay before pollution control of the Xiaoqing River, decreased in 2018, whereas the abundance of common dominant freshwater species (e.g., Merismopedia sp. and Synedra spp.) increased significantly. Redundancy analysis (RDA) showed that the phytoplankton community was significantly related to nitrogen, phosphate (negative correlation), and salinity (negative correlation) after pollution control of the Xiaoqing River, indicating that the variation in nutrient concentration and the structure of river runoff input may be the main factors affecting phytoplankton community and dominant species structure.

Assessment of pulmonary toxicity of potential antioxidant drug PEGylated nanoceria after intratracheal instillation in rats.

Cerium oxide (CeO2 ) nanoparticles have unique redox properties and exert excellent antioxidant effects in the biological environment. In recent years, many researchers have focused on the CeO2 nanoparticles as an effective antioxidant drug in the prevention and treatment of various diseases. However, the toxicity of CeO2 nanoparticles in vivo remains controversial and still needs intensive research. Therefore, the objective of this study is to investigate the pulmonary and systemic toxicity in rats after 14 days of exposure to the PEGylated CeO2 nanoparticles (abbreviated as CNPs; exposure dose of 2, 10, or 20 mg/kg) through a single intratracheal instillation (IT). We assessed the indicators of lung injury and the pathological damage degree of lung tissue. The bronchoalveolar lavage fluid (BALF) analysis and lung histopathology revealed the occurrence of slight pulmonary inflammation in the 20-mg/kg experimental group rats. However, the inflammation factors in the lung tissue of every group rats did not significantly increase, and the levels of superoxide dismutase (SOD) and glutathione (GSH) in lung tissue homogenate rose considerably in the experimental groups. Collectively, these results indicated that pulmonary exposure by the high dose of CNPs could induce mild pulmonary inflammation but did not cause severe systemic toxicity. Moreover, we speculate that the mechanism of pulmonary toxicity of CNPs in rats was due to the autophagic death of healthy lung epithelial cells mediated by endoplasmic reticulum stress. Our results implicate that CNPs can be safely used as an antioxidant drug for the oxidative stress pulmonary diseases.

Acoustic inerter: Ultra-low frequency sound attenuation in a duct.

This letter investigates an acoustic metamaterial exhibiting a unique sound pressure amplification mechanism for ultra-low frequency sound attenuation. The system is constructed by integrating a flexible panel into the side-branch duct of a Herschel-Quincke (HQ) tube. A new peak emerges in the Sound Transmission Loss (STL) at a frequency far lower than the frequencies of the HQ tube-induced STL peaks. It cannot, after careful comparisons, be attributed to any local resonances, including structural resonances of the flexible panel or air resonances inside the side-branch cavities. To explain the underlying physics, several numerical simulations are performed. The results reveal that analog to a mechanical inerter, a "push-pull" force is created by the sound pressure difference between the sub-cavities in which a pressure amplification mechanism is generated at the interface of the embedded panel. This force is large enough to activate an out-of-plane motion of the flexible panel, trapping the incident sound power in a circular flow around the duct-branch loop. The unique phenomenon is successfully reproduced in experiment, where the flexible panel is made of carbon fiber. The proposed acoustic metamaterial can be used as silencing components for ultra-low frequency noise control in duct.

Zn2+ Doped Ultrasmall Prussian Blue Nanotheranostic Agent for Breast Cancer Photothermal Therapy under MR Imaging Guidance.

Prussian blue nanoprobes are widely studied and applied in tumor photothermal therapy (PTT) and magnetic resonance imaging (MRI), due to their low toxicity and excellent in vivo performance. However, the sizes of hitherto reported Prussian blue nanoprobes are generally larger than 50 nm, which greatly influence cell phagocytosis, in vivo circulation, and biodistribution. In this work, a novel method of doping zinc ions is used to control the size of Prussian blue nanoprobes. Consequently, the performances of the nanoprobes in PTT and MRI are both significantly improved. The results show that the minimum size of Prussian blue nanoprobes achieved by doping 10% zinc ions (abbreviated as SPBZn(10%)) is 3.8 ± 0.90 nm, and the maximum specific absorption coefficient, photothermal conversion efficiency, and longitudinal relaxation rates are 1.78 L g-1 cm-1 , 47.33%, and 18.40 mm-1 s-1 , respectively. In addition, the SPBZn(10%) nanoprobes provide excellent PTT efficacy on 4T1 tumor cells (killing rate: 90.3%) and breast cancer model (tumor inhibition rate: 69.4%). Toxicological experiment results show that the SPBZn(n%) nanoprobes exhibit no obvious in vitro cytotoxicity and they can be used safely in mice at doses below 100 mg kg-1 . Therefore, SPBZn(10%) nanoprobes can potentially be used for effective cancer theranostics.

Transparent Tunable Acoustic Absorber Membrane Using Inkjet-Printed PEDOT:PSS Thin-Film Compliant Electrodes.

Window glasses can block noise from outdoor, but they reverberate sound within a large indoor space. Microperforated glass absorbers have been developed to absorb sound over a fixed but narrow bandwidth. To tune the frequency spectrum of acoustic absorption, we developed a transparent tunable acoustic absorber based on microperforated dielectric elastomer actuator (MPDEA) and transparent compliant electrodes. Such transparent compliant electrodes were inkjet printed from Triton X-plasticized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) ink, which shows improved wettability on the acrylate dielectric elastomer substrate. These transparent polymeric electrodes are softer with uptake of moisture while being self-clearable and durable. A single layer of MPDEA using two inkjet-printed electrodes is 78.64% clear, but the clarity of a two-layer MPDEA decreases to 61.8%. Among the two designs, the two-layer MPDEA exhibits a broader acoustic absorption bandwidth of 444 Hz for absorbing more than 80% of the sound energy. Inactivated resonant frequency of this MPDEA is 1170 Hz, whereas the 6 kV activation can reduce the resonant frequency for 15.2% by causing 9% hole-diameter contraction. This transparent tunable acoustic absorber can be fitted to window glass; its acoustic performance is better than that of translucent curtains.

An electronically tunable duct silencer using dielectric elastomer actuators.

A duct silencer with tunable acoustic characteristics is presented in this paper. Dielectric elastomer, a smart material with lightweight, high elastic energy density and large deformation under high direct current/alternating current voltages, was used to fabricate this duct silencer. The acoustic performances and tunable mechanisms of this duct silencer were experimentally investigated. It was found that all the resonance peaks of this duct silencer could be adjusted using external control signals without any additional mechanical part. The physics of the tunable mechanism is further discussed based on the electro-mechanical interactions using finite element analysis. The present promising results also provide insight into the appropriateness of the duct silencer for possible use as next generation acoustic treatment device to replace the traditional acoustic treatment.

[Determination of naphthenic acids in distillates of crude oil by gas chromatography/chemical ionization-mass spectrometry].

The petroleum carboxylic acids in 200-420 degrees C distillate of crude oil were separated by the extraction with column chromatography on an anion exchange resin. The effect of the composition and structure of naphthenic acids on separation were studied by the infra-red (IR) spectroscopic techniques. Naphthenic acids and iso-butane reagent gas were introduced into the ion source for chemical ionization, in which the ions represented by [M + C4H9]+ were used to calculate the relative molecular mass for each acid. Based on the mass spectra of pure fatty and naphthenic acids, in combination with the z-series formula CnH(2n + z)O2, the naphthenic acids can be classified into fatty, mono-, bi- ... hexa-cyclic types. The results indicated that the relative molecular mass range of naphthenic acids in this distillates was 170-510, and the carbon number range was C10-C35. The contents of bi-cyclic and tri-cyclic naphthenic acids were higher than others.