Tongji University

About: Tongji University is a education organization based out in Shanghai, China. It is known for research contribution in the topics: Population & Adsorption. The organization has 76116 authors who have published 81176 publications receiving 1248911 citations. The organization is also known as: Tongji & Tóngjì Dàxué.

Precursors of dichloroacetamide, an emerging nitrogenous DBP formed during chlorination or chloramination.

Abstract: Haloacetamides (HAcAms) are an emerging class of nitrogenous disinfection byproducts (N-DBPs). However, there is a limited understanding about the precursors of HAcAms. In this study, we screened the precursors of dichloroacetamide (DCAcAm), the most commonly identified HAcAm in chlorinated or chloraminated drinking water. DCAcAm formation potential (FP) of raw water samples collected in different months from a reservoir in China was determined during chlorination, and the highest DCAcAm FP typically occurred in the summer samples. Dissolved organic matter (DOM) in a representative summer raw water sample was separated into six fractions by a series of resin elutions. Among them, hydrophilic acid (HiA) DOM showed the maximum DCAcAm FP, followed by hydrophilic bases (HiB) and, to a much lower extent, hydrophobic acids (HoA). Fluorescence excitation-emission matrix (EEM) spectra revealed that a mass of protein-like substances in the HiA fraction, made up of amino acids (AAs), were the likely DCAcAm precursors. Finally, we investigated the DCAcAm yields of 20 AAs during chlorination. Among them, seven AAs (aspartic acid, histidine, tyrosine, tryptophan, glutamine, asparagine, phenylalanine) could form DCAcAm during chlorination, with the corresponding DCAcAm yields of 0.231, 0.189, 0.153, 0.104, 0.078, 0.058, and 0.050 mmol/mol AA.

Physical-Layer Security with Multiuser Scheduling in Cognitive Radio Networks

Abstract: In this paper, we consider a cognitive radio network that consists of one cognitive base station (CBS) and multiple cognitive users (CUs) in the presence of multiple eavesdroppers, where CUs transmit their data packets to CBS under a primary user's quality of service (QoS) constraint while the eavesdroppers attempt to intercept the cognitive transmissions from CUs to CBS. We investigate the physical-layer security against eavesdropping attacks in the cognitive radio network and propose the user scheduling scheme to achieve multiuser diversity for improving the security level of cognitive transmissions with a primary QoS constraint. Specifically, a cognitive user (CU) that satisfies the primary QoS requirement and maximizes the achievable secrecy rate of cognitive transmissions is scheduled to transmit its data packet. For the comparison purpose, we also examine the traditional multiuser scheduling and the artificial noise schemes. We analyze the achievable secrecy rate and intercept probability of the traditional and proposed multiuser scheduling schemes as well as the artificial noise scheme in Rayleigh fading environments. Numerical results show that given a primary QoS constraint, the proposed multiuser scheduling scheme generally outperforms the traditional multiuser scheduling and the artificial noise schemes in terms of the achievable secrecy rate and intercept probability. In addition, we derive the diversity order of the proposed multiuser scheduling scheme through an asymptotic intercept probability analysis and prove that the full diversity is obtained by using the proposed multiuser scheduling.

Alginate/graphene double-network nanocomposite hydrogel beads with low-swelling, enhanced mechanical properties, and enhanced adsorption capacity

Abstract: As a novel material, double network hydrogels have attracted great attention in recent years for their excellent mechanical properties; however, several other characteristics are yet to be improved. Here we report the synthesis of a novel alginate/reduced graphene oxide (RGO) double-network (GAD) hydrogel through a facile method, and investigate the GAD's mechanical properties, stability, and adsorption capacity in comparison with those of an alginate/RGO single network hydrogel (GAS). To produce the GAD, the first network of alginate is formed with randomly distributed graphene oxide (GO), resulting in the GAS; then the GAS is treated by a hydrothermal reduction, through which the GO is reduced and self-assembles into a second RGO network interpenetrating with the first, alginate network, forming the double-network GAD. The mechanism of the GAD formation is investigated and the property differences between the GAS and the GAD are examined. The resulting GAD exhibits a higher Young's modulus than the GAS, and the modulus increases with GO concentrations. The GAD also has a lower swelling ratio than the GAS, which leads to improved gel stability in highly concentrated alkali/salt solutions. The GAD beads exhibit an excellent adsorption capacity (Cu2+, 169.5 mg g−1 and Cr2O72−, 72.5 mg g−1) for heavy metal ions, far better than that of the GAS. Even after 10 regeneration cycles, both GAS and GAD can still retain their considerable adsorption capacity for metals. The results of this work are of great significance to double network gel research, especially for environmental applications. With good stability, adsorption capacity, and regeneration ability, the double network gel could be a promising adsorbent nanomaterial for pollutant removal from aqueous solutions.

Recent progress in photofunctional lanthanide hybrid materials

Abstract: This critical review mainly focuses on recent research progress in photofunctional lanthanide hybrid materials The review covers hybrids with complexes of organically modified silanes as precursors for sol–gel processing, hybrids with lanthanide complex units grafted onto the interior of mesoporous hosts, hybrids with lanthanide complex units on polymer chains, and other non-silica or composite-based lanthanide hybrids The photophysical properties of lanthanide hybrids are also discussed Finally, future challenges and opportunities in this field are discussed