Polybrominated Diphenyl Ethers (PBDEs) Emitted from Heating Machine for Waste Printed Wiring Boards Disassembling

AbstractPolybrominated diphenyl ethers (PBDEs) contained in waste printed wiring board (PWB) matrix and surface dust can be emitted into the air during thermal process, which is widely used to detach the electronic components from the base boards of waste PWB. In this study, PBDEs concentrations in air and dust samples were detected in a PWB-heating workshop. The results showed that the mean concentrations of ∑8PBDEs in PM10 and TSP were 479 and 1670 ng/m3, respectively. Compared with surface dust collected from waste PWB (15600 ng/g), PBDEs concentrations in dust from the workshop floor (31100 ng/g), heating machine inside (84700 ng/g), and the cyclone extractor (317000 ng/g), were condensed after thermal process. All the results showed that recycling of waste PWB was an important source of PBDEs emission

Intelligent optical performance monitor using multi-task learning based artificial neural network

An intelligent optical performance monitor using multi-task learning based artificial neural network (MTL-ANN) is designed for simultaneous OSNR monitoring and modulation format identification (MFI). Signals' amplitude histograms (AHs) after constant module algorithm are selected as the input features for MTL-ANN. The experimental results of 20-Gbaud NRZ-OOK, PAM4 and PAM8 signals demonstrate that MTL-ANN could achieve OSNR monitoring and MFI simultaneously with higher accuracy and stability compared with single-task learning based ANNs (STL-ANNs). The results show an MFI accuracy of 100% and OSNR monitoring root-mean-square error of 0.63 dB for the three modulation formats under consideration. Furthermore, the number of neuron needed for the single MTL-ANN is almost the half of STL-ANN, which enables reduced-complexity optical performance monitoring devices for real-time performance monitoring

Biaxial creep test study on the influence of structural anisotropy on rheological behaviour of hard rock

Rheological characteristics are one of most important properties needed to be considered for the designing and construction for the long term stability and serviceability of underground structures in the rock mass. Up to date, although extensive studies on the rheological properties of rocks are available in the literature, most of existing studies reported the strain-time data for the axial deformation through compression rheological method and did not mention the lateral deformation, and mainly focused on the soft rocks at shallow depth. Thus, very limited attention has been paid to the rheological properties of deep and hard rock, neglecting the effects of structural anisotropy on the rheological properties. This paper presents a comprehensive in-depth study on the rheological behaviours of super-deep hard rock considering the effects of structural anisotropy by using the uniaxial and biaxial creep tests. The results revealed that significant creep behaviour can be observed in the hard rock specimens under high stress in the in-situ conditions, and the strain-time behaviour of hard rock exhibited brittle failure. The strain-time curves of hard rock exhibited two obvious phases of instantaneous creep and steady state creep without the phase of accelerated creep. Moreover, it was observed that the rheological behaviours, including the instantaneous modulus, transient creep duration, axial and lateral creep deformations, steady state creep rate, volumetric strain and contraction ratio are strongly affected by the structural anisotropy. Based on the experimental data, empirical models of the parameters governing creep behaviour have been established

Intrinsic Lithiophilicity of Li–Garnet Electrolytes Enabling High‐Rate Lithium Cycling

Solid‐state lithium batteries are widely considered as next‐generation lithium‐ion battery technology due to the potential advantages in safety and performance. Among the various solid electrolyte materials, Li–garnet electrolytes are promising due to their high ionic conductivity and good chemical and electrochemical stabilities. However, the high electrode/electrolyte interfacial impedance is one of the major challenges. Moreover, short circuiting caused by lithium dendrite formation is reported when using Li–garnet electrolytes. Here, it is demonstrated that Li–garnet electrolytes wet well with lithium metal by removing the intrinsic impurity layer on the surface of the lithium metal. The Li/garnet interfacial impedance is determined to be 6.95 Ω cm2 at room temperature. Lithium symmetric cells based on the Li–garnet electrolytes are cycled at room temperature for 950 h and current density as high as 13.3 mA cm−2 without showing signs of short circuiting. Experimental and computational results reveal that it is the surface oxide layer on the lithium metal together with the garnet surface that majorly determines the Li/garnet interfacial property. These findings suggest that removing the superficial impurity layer on the lithium metal can enhance the wettability, which may impact the manufacturing process of future high energy density garnet‐based solid‐state lithium batteries.By removing the impurity layer on the surface of the lithium metal, Li–garnet electrolytes are demonstrated to well wet the lithium metal, rendering a Li/garnet interfacial impedance of 6.95 Ω cm2, stable galvanostatic cycling for 950 h, and a current density as high as 13.3 mA cm−2 without showing any sign of short circuiting at room temperature.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154451/1/adfm201906189-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154451/2/adfm201906189.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154451/3/adfm201906189_am.pd

Local Heat Transfer Measurements on a Rotating Flat Blade Model with a Single Film Hole

An experimental study was performed to measure the heat transfer coefficient distributions on a flat blade model under rotating operating conditions. A steady-state thermochromic liquid crystal technique was employed to measure the surface temperature, and all the signals from the rotating reference frame were collected by the telemetering instrument via a wireless connection. Both air and CO2 were used as coolant. Results show that the rotational effect has a significant influence on the heat transfer coefficient distributions. The profiles of hg/h0, which is the ratio of heat transfer coefficient with film cooling to that without film cooling, deflect towards the high-radius locations on both the pressure surface and suction surface as the rotation number (Rt) increases, and the deflective tendency is more evident on the suction surface. The variations in mainstream Reynolds number (ReD) and blowing ratio (M) present different distributions of hg/h0 on the pressure and suction surfaces, respectively. Furthermore, the coolant used for CO2 injection is prone to result in lower heat transfer coefficients.Peer reviewe

The Low Abundance of CpG in the SARS-CoV-2 Genome Is Not an Evolutionarily Signature of ZAP

The zinc finger antiviral protein (ZAP) is known to restrict viral replication by binding to the CpG rich regions of viral RNA, and subsequently inducing viral RNA degradation. This enzyme has recently been shown to be capable of restricting SARS-CoV-2. These data have led to the hypothesis that the low abundance of CpG in the SARS-CoV-2 genome is due to an evolutionary pressure exerted by the host ZAP. To investigate this hypothesis, we performed a detailed analysis of many coronavirus sequences and ZAP RNA binding preference data. Our analyses showed neither evidence for an evolutionary pressure acting specifically on CpG dinucleotides, nor a link between the activity of ZAP and the low CpG abundance of the SARS-CoV-2 genome