Liquid crystal monomers (LCMs) in liquid crystal displays (LCDs) may be released into the environment, especially in electronic waste (e-waste) recycling industrial parks with a high pollution risk. However, little has been known about the environmental release and human exposure to LCMs until now. Herein, a total of 45 LCMs were detected in LCDs of commonly used smartphones and computers by high-resolution mass spectrometry with suspect screening analysis. Fluorinated biphenyls and their analogs were the dominant LCMs. Based on available standards of the screening results and previous studies, 55 LCMs were quantified in samples from an e-waste recycling industrial park in Central China. The LCMs were frequently detected in outdoor dust (n = 43), workshop #1 indoor dust (n = 53), and hand (n = 43) and forehead wipes (n = 43), with median concentrations of 6950 ng/g, 67,400 ng/g, 46,100 ng/m2, and 62,100 ng/m2, respectively. The median estimated daily intake values of the LCMs via dust ingestion and dermal absorption were 48.3 and 16.5 ng/kg body weight/day, respectively, indicating a high occupational exposure risk of these compounds. In addition, 16 LCMs were detected in the serum of eight elderly people (≥60 years old) with over 5 years of experience in e-waste dismantling operations, resulting in a total concentration range of 3.9–26.3 ng/mL.
Before mid-Tang Dynasty,strengthening of the woman virginity idea was a repeating and twisting course;After Song Dynasty,the strong idea of the woman virginity idea demonstrated the momentum of the acceleration with fast-developing straight line.So,there were two main lines of the theory of woman virginity idea,one is that woman virginity idea was strengthened by Neo-Confucianism and the ruling group;the other is the normal people who changed from ignoramce to acceptance.The second main line shortened the distance progressively.In the Ming Dynasty,the two main lines were integrated,the second main line was assimilated by the first main line,virginity idea became social ethics that generally believed in different levels.
Melamine (MEL) and its derivatives are increasingly applied as nitrogenous flame retardants in consumer products. Nevertheless, limited information is available on their environmental occurrence and subsequent human exposure via multiple exposure pathways. In this study, we analysed MEL and its derivatives in dust (indication of the dust ingestion route) and hand wipe samples (indication of the hand-to-mouth route) collected in various microenvironments. The levels of ∑MELs in both dust (median: 24,100 ng/g) and participant hand samples (803 ng/m2) collected in e-waste dismantling workshops were significantly higher than those in samples collected in homes (15,600 ng/g and 196 ng/m2, respectively), dormitories (13,100 ng/g and 227 ng/m2, respectively) and hotel rooms (11,800 ng/g and 154 ng/m2, respectively). Generally, MEL dominated in dust samples collected in e-waste dismantling workshops, whereas cyanuric acid dominated in hand wipe samples. This may occur partly because the latter is an ingredient in disinfection products, which are more frequently employed in daily lives during the COVID-19 pandemic. Exposure assessment suggests that dust ingestion is an important exposure pathway among dismantling workers and the general population, whereas hand-to-mouth contact could not be overlooked in certain populations, such as children and dismantling workers not wear gloves at work.
In-plane anisotropy of layered materials adds another dimension to their applications, opening up avenues in diverse angle-resolved devices. However, to fulfill a strong inherent in-plane anisotropy in layered materials still poses a significant challenge, as it often requires a low-symmetry nature of layered materials. Here, we report the fabrication of a member of layered semiconducting AIIIBVI compounds, TlSe, that possesses a low-symmetry tetragonal structure and investigate its anisotropic light–matter interactions. We first identify the in-plane Raman intensity anisotropy of thin-layer TlSe, offering unambiguous evidence that the anisotropy is sensitive to crystalline orientation. Further in-situ azimuth-dependent reflectance difference microscopy enables the direct evaluation of in-plane optical anisotropy of layered TlSe, and we demonstrate that the TlSe shows a linear dichroism under polarized absorption spectra arising from an in-plane anisotropic optical property. As a direct result of the linear dichroism, we successfully fabricate TlSe devices for polarization-sensitive photodetection. The discovery of layered TlSe with a strong in-plane anisotropy not only facilitates its applications in linear dichroic photodetection but opens up more possibilities for other functional device applications.
In most design activities, the design decision-making process is not recorded explicitly, which has severe impacts on design modification and design reuse. This paper presents a design thinking process model that records not only the design procedure and decisions but also the design intents behind them. The design thinking process is evolved based on the interaction among design intents, solutions and operations. Three types of inconsistency situation are analyzed and the design decision support prototype system is presented for capturing and managing the design thinking process.
In this paper, an enhanced phase-shift migration-based image reconstruction (EPSM-IR) algorithm was investigated to improve the computation efficiency for three-dimensional (3-D) terahertz (THz) holographic imaging. In the proposed algorithm, an appropriate decomposition of the phase-shift operator was performed and a fast algorithm based on FFT was introduced to solve the integral transformation which is the most time-consuming step in the conventional phase-shift migration. The analytical expression of the reconstructed 3-D point-spread function (PSF) was derived based on the EPSM-IR algorithm. The reduction of the computation cost was evaluated quantitatively as compared with the conventional phase-shift migration. Simulation results with fairly good agreement were given to verify the proposed algorithm. Finally, a monostatic prototype imager with a Gaussian beam transceiver was designed for the proof-of-principle experiments in the 0.2-THz band. The 3-D image results of a target with metal strips and a mannequin with concealed threat objects were given to demonstrate the effectiveness and the efficiency of the 3-D EPSM-IR algorithm.
We demonstrate the experimental realization of a field concentrator based on transmission line (TL) networks. The off-diagonal elements of the material tensors for implementing a field concentrator are controlled by the coupling between the different branches of tensor TL metamaterials. Taking advantage of full parameters realization, the effect of compressing the electromagnetic (EM) field into an enclosed region to achieve higher EM energy density (EED) is verified. The nonresonant property of the TL structure leads to a relatively broad bandwidth of the EM field concentration function, which is quantitatively evaluated based on our experimental results.
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