Microplastics (MPs), the appearance of which has gained considerable interest, can act as vectors to transport other pollutants such as metals into organisms. In this study, the sorption isotherms of ...three model heavy metals (i.e., Cu2+, Cd2+, and Pb2+) on four virgin plastic particles including chlorinated polyethylene (CPE), PVC, and two polyethylene plastic particles (i.e., LPE and HPE). HPE and LPE were investigated. The results showed that MPs can load high amounts of Pb2+, Cu2+ and Cd2+. The sorption affinity of the three metals to the model MPs followed the sequence of CPE > PVC > HPE > LPE. The adsorption process was affected by the chemical structure and electronegativity of the sorbents, and seemed irrelevant to the crystallinity of MPs. For the three metals, Pb2+ exhibited significantly stronger sorption than did Cu2+ and Cd2+ due to the strong electrostatic interaction. Moreover, pH can significantly affect the sorption of metals on MPs, but ionic strength exerted a relatively slight effect on this process. In brief, the electrostatic interaction played an important role in the sorption of Pb2+ to model MPs. For Cd2+ and Cu2+, sorption was determined by electrostatic interaction together with surface complexation onto the plastic surface. This study indicates that depending on the surface physicochemical properties of MPs the adsorption behavior can vary significantly. Therefore, the adsorption process of metals on MPs should be readily affected by other environmental mediums in the environment. The study provides additional insight into the behavior of MPs as a vector of metals.
•Sorption of Cu2+, Cd2+, and Pb2+ on four virgin plastic particles was investigated.•The sorption strength followed the order of Pb2+>Cu2+>Cd2+.•PH and ionic strength can affect the sorption of metals on MPs.•Electrostatic interaction played an important role in the sorption of Pb2+ to MPs.•Electrostatic interaction and complexation determined the sorption of Cd2+ and Cu2+.
This paper studies the massive MIMO full-duplex relaying (MM-FDR), where multiple source-destination pairs communicate simultaneously with the help of a common full-duplex relay equipped with very ...large antenna arrays. Different from the traditional MM-FDR protocol, a general model where sources/destinations are allowed to equip with multiple antennas is considered. In contrast to the conventional MIMO system, massive MIMO must be built with low-cost components which are prone to hardware impairments. In this paper, the effect of hardware impairments is taken into consideration, and is modeled using transmit-receive distortion noises. We propose a low complexity hardware impairments aware transceiver scheme (named as HIA scheme) to mitigate the distortion noises by exploiting the statistical knowledge of channels and antenna arrays at sources and destinations. A joint degree of freedom and power optimization algorithm is presented to further optimize the spectral efficiency of HIA based MM-FDR. The results show that the HIA scheme can mitigate the "ceiling effect" appears in traditional MM-FDR protocol, if the numbers of antennas at sources and destinations can scale with that at the relay.
Water serves as an inert environment for the dispersion and application of many kinds of herbicides. Viologen compounds, a type of widely used but highly toxic herbicide, are stable in bulk water, ...whose half-life can be up to 23 weeks in natural water, imposing a severe health risk to mammals. In this study, we present the striking results of the spontaneous and ultrafast reduction-induced degradation of three viologen compounds in water microdroplets and provide the concentration, time, temperature dependence, mechanism, and scale-up of the reactions. We postulate that the electrons existing at the air-water interface of the microdroplets due to the unique redox potential therein initiate the reduction, from which further degradation occurs. The host-guest complexation between cucurbit7uril and viologens only slightly changes the redox potential of viologens in the bulk but completely inhibits the reactions in microdroplets, adding to the uniqueness of the redox potentials at the air-water interfaces of microdroplets. Taken together, microdroplets might have been functioning as naturally occurring ubiquitous tiny electrochemical cells for a plethora of unique redox reactions that were thought to be impossible in the bulk water.
Polyaniline has been widely used in high-performance pseudocapacitors, due to its low cost, easy synthesis, and high theoretical specific capacitance. However, the poor mechanical properties of ...polyaniline restrict its further development. Compared with polyaniline, functionalized carbon materials have excellent physical and chemical properties, such as porous structures, excellent specific surface area, good conductivity, and accessibility to active sites. However, it should not be neglected that the specific capacity of carbon materials is usually unsatisfactory. There is an effective strategy to combine carbon materials with polyaniline by a hybridization approach to achieve a positive synergistic effect. After that, the energy storage performance of carbon/polyaniline hybridization material has been significantly improved, making it a promising and important electrode material for supercapacitors. To date, significant progress has been made in the synthesis of various carbon/polyaniline binary composite electrode materials. In this review, the corresponding properties and applications of polyaniline and carbon hybrid materials in the energy storage field are briefly reviewed. According to the classification of different types of functionalized carbon materials, this article focuses on the recent progress in carbon/polyaniline hybrid materials, and further analyzes their corresponding properties to provide guidance for the design, synthesis, and component optimization for high-performance supercapacitors.
Co-time co-frequency uplink and downlink (CCUD) transmission was considered challenging in the cellular system due to the strong self-interference (SI) between the transmitter and receiver of base ...station (BS). In this paper, by investigating the beam-domain representation of channels based on the basis expansion model, we propose a beam-domain full-duplex (BDFD) massive multiple-input multiple-output (MIMO) scheme to make the CCUD transmission possible. The key idea of the BDFD scheme lies in intelligently scheduling the uplink and downlink user equipment (UE) based on the beam-domain distributions of their associated channels to mitigate SI and enhance transmission efficiency. We show that the BDFD scheme achieves significant savings in uplink/downlink training resource and achieves uplink and downlink sum capacities simultaneously as the number of BS antennas approaches infinity. The superiority of the BDFD scheme over the traditional time-division duplex (TDD)/frequency-division duplex (FDD) massive MIMO is evaluated through simulation for the macrocell environment. The results show that the spectral efficiency gain can even exceed 2× in the specific scenarios, since the BDFD scheme utilizes the time-frequency resource more efficiently in both the training and data transmission phases.
Seepage erosion around the underground pipelines will produce various adverse influences on the stratum stability and the structural safety. It involves behaviours at three scales, that is, ...particle-scale, cell-scale and engineering-scale. The problem relies on the fact that finding general equations for the granular media is difficult due to the changing nature of how solids flow, so that the continuous approach is unavailable to directly describe the phenomenon. Hence, DEM simulations are firstly conducted in this study to quantify the relationship between the fine particle loss (ΔFC = 0, 5%, 10%, 15%, 20%, 25%, 30%) and the mechanical properties of soil elements, upscaling particle to cell. Considering two initial fine grain contents (S6:4, S3:7), the empirical equations of soil mechanical parameters εve, E0, φ and c changing with the fine particle loss ΔFC are obtained by regression analysis. Then, based on the corresponding constitutive parameters of different erosional stages, FEM simulations at the engineering scale are conducted to analyse the structural mechanical response to the seepage erosion, upscaling cell to engineering. This study reveals the multiscale response of the seepage erosion in the sandy strata, and helps in providing the practical guidance for engineering application and the reference for the next multiscale parallel computation on this issue.
•The erosional influence on soil mechanical properties is quantitatively characterized by DEM simulations.•Regression equations of soil mechanical parameters with erosion are fitted according to the DEM simulation result.•Varying degrees of eroded stratum are modelled by FEM based on the result of DEM simulations.•The mechanical response of pipe structure to seepage erosion is analysed by using the FEM model.
Bacillus Calmette–Guerin (BCG), the only current vaccine against tuberculosis (TB) that is licensed in clinics, successfully protects infants and young children against several TB types, such as TB ...meningitis and miliary TB, but it is ineffective in protecting adolescents and adults against pulmonary TB. Thus, it is a matter of the utmost urgency to develop an improved and efficient TB vaccine. In this milieu, virus-like particles (VLPs) exhibit excellent characteristics in the field of vaccine development due to their numerous characteristics, including but not limited to their good safety without the risk of infection, their ability to mimic the size and structure of original viruses, and their ability to display foreign antigens on their surface to enhance the immune response. In this study, the HPV16 L1 capsid protein (HPV16L1) acted as a structural vaccine scaffold, and the extracellular domain of Ag85B was selected as the M. tb immunogen and inserted into the FG loop of the HPV16 L1 protein to construct chimeric HPV16L1/Ag85B VLPs. The chimeric HPV16L1/Ag85B VLPs were produced via the Pichia pastoris expression system and purified via discontinuous Optiprep density gradient centrifugation. The humoral and T cell-mediated immune response induced by the chimeric HPV16L1/Ag85B VLP was studied in female C57BL/c mice. We demonstrated that the insertion of the extracellular domain of Ag85B into the FG loop of HPV16L1 did not affect the in vitro stability and self-assembly of the chimeric HPV16L1/Ag85B VLPs. Importantly, it did not interfere with the immunogenicity of Ag85B. We observed that the chimeric HPV16L1/Ag85B VLPs induced higher Ag85B-specific antibody responses and elicited significant Ag85B-specific T cell immune responses in female C57BL/c mice compared with recombinant Ag85B. Our findings provide new insights into the development of novel chimeric HPV16L1/TB VLP-based vaccine platforms for controlling TB infection, which are urgently required in low-income and developing countries.
Tuberculosis (TB) remains a serious public health threat around the world. An effective vaccine is urgently required for cost-effective, long-term control of TB. However, the only licensed vaccine ...Bacillus Calmette-Guerin (BCG) is limited to prevent TB for its highly variable efficacy. Substantial progress has been made in research and development (R&D) of TB vaccines in the past decades, and a dozen vaccine candidates, including live attenuated mycobacterial vaccines, killed mycobacterial vaccines, adjuvanted subunit vaccines, viral vector vaccines, and messenger RNA (mRNA) vaccines were developed in clinical trials to date. Nevertheless, many challenges to the successful authorization for the use and deployment of an effective tuberculosis vaccine remain. Therefore, it is still necessary and urgent to continue exploring new vaccine construction approaches. Virus-like particles (VLPs) present excellent prospects in the field of vaccine development because of their helpful immunological features such as being safe templates without containing viral nucleic acid, repetitive surface geometry, conformational epitopes similar to natural viruses, and enhancing both innate and adaptive immune responses. The marketization process of VLP vaccines has never stopped despite VLP vaccines face several shortcomings such as their complex and slow development process and high production cost, and several VLP-based vaccines, including vaccines against Human papillomavirus (HPV), Hepatitis B Virus (HBV) and malaria, are successfully licensed for use at the market. In this review, we provide an update on the current progress regarding the development of TB vaccines in clinical trials and seek to give an overview of VLP-based TB vaccine candidates.
PDF
