Lithium–sulfur (Li–S) batteries hold the promise of the next generation energy storage system beyond state‐of‐the‐art lithium‐ion batteries. Despite the attractive gravimetric energy density (WG), ...the volumetric energy density (WV) still remains a great challenge for the practical application, based on the primary requirement of Small and Light for Li–S batteries. This review highlights the importance of cathode density, sulfur content, electroactivity in achieving high energy densities. In the first part, key factors are analyzed in a model on negative/positive ratio, cathode design, and electrolyte/sulfur ratio, orientated toward energy densities of 700 Wh L−1/500 Wh kg−1. Subsequently, recent progresses on enhancing WV for coin/pouch cells are reviewed primarily on cathode. Especially, the “Three High One Low” (THOL) (high sulfur fraction, high sulfur loading, high density host, and low electrolyte quantity) is proposed as a feasible strategy for achieving high WV, taking high WG into consideration simultaneously. Meanwhile, host materials with desired catalytic activity should be paid more attention for fabricating high performance cathode. In the last part, key engineering technologies on manipulating the cathode porosity/density are discussed, including calendering and dry electrode coating. Finally, a future outlook is provided for enhancing both WV and WG of the Li–S batteries.
The volumetric energy density (WV) of lithium–sulfur batteries is critical for mobile applications. Key factors that dominate WV progress on WV research are analyzed, and technologies for tuning cathode structure are discussed. A “three‐high one‐low (THOL)” strategy is proposed for high WV and gravimetric energy density (WG), and catalytic hosts are important to unlock the sulfur electroactivity.
In this paper, we propose multi-input multi-output (MIMO) beamforming designs towards joint radar sensing and multi-user communications. We employ the Cramér-Rao bound (CRB) as a performance metric ...of target estimation, under both point and extended target scenarios. We then propose minimizing the CRB of radar sensing while guaranteeing a pre-defined level of signal-to-interference-plus-noise ratio (SINR) for each communication user. For the single-user scenario, we derive a closed form for the optimal solution for both cases of point and extended targets. For the multi-user scenario, we show that both problems can be relaxed into semidefinite programming by using the semidefinite relaxation approach, and prove that the global optimum can be generally obtained. Finally, we demonstrate numerically that the globally optimal solutions are reachable via the proposed methods, which provide significant gains in target estimation performance over state-of-the-art benchmarks.
This paper investigates an intelligent reflecting surface (IRS)-aided multi-cell multiple-input single-output (MISO) network with a set of multi-antenna base stations (BSs) each communicating with ...multiple single-antenna users, in which an IRS is dedicatedly deployed for assisting the wireless transmission and suppressing the inter-cell interference. Under this setup, we jointly optimize the coordinated transmit beamforming vectors at the BSs and the reflective beamforming vector (with both reflecting phases and amplitudes) at the IRS, for the purpose of maximizing the minimum weighted signal-to-interference-plus-noise ratio (SINR) at the users, subject to the individual maximum transmit power constraints at the BSs and the reflection constraints at the IRS. To solve the non-convex min-weighted-SINR maximization problem, we first present an exact -alternating-optimization approach to optimize the transmit and reflective beamforming vectors in an alternating manner, in which the transmit and reflective beamforming optimization subproblems are solved exactly in each iteration by using the techniques of second-order-cone program (SOCP) and semi-definite relaxation (SDR), respectively. However, the exact-alternating-optimization approach has high computational complexity, and may lead to compromised performance due to the uncertainty of randomization in SDR. To avoid these drawbacks, we further propose an inexact -alternating-optimization approach, in which the transmit and reflective beamforming optimization subproblems are solved inexactly in each iteration based on the principle of successive convex approximation (SCA). In addition, to further reduce the computational complexity, we propose a low-complexity inexact-alternating-optimization design, in which the reflective beamforming optimization subproblem is solved more inexactly . Via numerical results, it is shown that the proposed three designs achieve significantly increased min-weighted-SINR values, as compared with benchmark schemes without the IRS or with random reflective beamforming. It is also shown that the inexact-alternating-optimization design outperforms the exact-alternating-optimization one in terms of both the achieved min-weighted-SINR value and the computational complexity, while the low-complexity inexact-alternating-optimization design has much lower computational complexity with slightly compromised performance. Furthermore, we show that our proposed design can be applied to the scenario with unit-amplitude reflection constraints, with a negligible performance loss.
Extracellular vesicles (EVs) are small, membrane-bound structures that are released from cells into the surrounding environment. These structures can be categorized as exosomes, microvesicles, or ...apoptotic vesicles, and they play an essential role in intercellular communication. These vesicles are attracting significant clinical interest as they offer the potential for drug delivery, disease diagnosis, and therapeutic intervention. To fully understand the regulation of intercellular communication through EVs, it is essential to investigate the underlying mechanisms. This review aims to provide a summary of the current knowledge on the intercellular communications involved in EV targeting, binding, and uptake, as well as the factors that influence these interactions. These factors include the properties of the EVs, the cellular environment, and the recipient cell. As the field of EV-related intercellular communication continues to expand and techniques improve, we can expect to uncover more information about this complex area, despite the current limitations in our knowledge.
Electrochemical conversion of N2 to NH3 offers a clean and energy‐saving solution for artificial NH3 production, but requires cost‐effective, steady and highly efficient catalysts to promote N2 ...reduction reaction (NRR). Herein, CuO employed as a new non‐noble‐metal NRR catalyst was investigated both experimentally and theoretically. When supporting the CuO nanoparticles on reduced graphene oxide (RGO), it was demonstrated that the resulting CuO/RGO nanocomposite could effectively and robustly catalyze NRR under ambient conditions. At −0.75 V versus reversible hydrogen electrode, the CuO/RGO exhibited a high NH3 yield of 1.8×10−10 mol s−1 cm−2 and Faradaic efficiency of 3.9 %, along with the excellent selectivity and high stability. Density functional theory (DFT) calculations revealed that the “Suf‐end” was the most effective mode for N2 adsorption on catalytic Cu atoms. In NRR process, the alternating associative route was the preferable pathway with *N2→*NNH being the rate‐determining step.
Sub or Suf? Suf CuO/RGO nanocomposite exhibited a high NH3 yield of 1.8×10−10 mol s−1 cm−2 and Faradaic efficiency of 3.9 % at −0.75 V versus reversible hydrogen electrode. Theoretical calculations revealed that the “Suf‐end” was the most effective mode for N2 adsorption on CuO and the *N2→*NNH is the rate‐determining step.
The electrochemical nitrogen reduction reaction (NRR) is a very efficient method for sustainable NH3 production, but it requires effective catalysts to expedite the NRR kinetics and inhibit the ...concomitant hydrogen evolution reaction (HER). Two-dimensional (2D)/2D interface engineering is an effective method to design powerful catalysts due to intimate face-to-face contact of two 2D materials that facilitates the strong interfacial electronic interactions. Herein, we explored a 2D/2D MoS2/C3N4 heterostructure as an active and stable NRR catalyst. MoS2/C3N4 exhibited a conspicuously improved NRR performance with an NH3 yield of 18.5 μg h–1 mg–1 and a high Faradaic efficiency (FE) of 17.8% at −0.3 V, far better than those of the individual MoS2 or C3N4 component. Density functional theory calculations revealed that the interfacial charge transport from C3N4 to MoS2 could enhance the NRR activity of MoS2/C3N4 by promoting the stabilization of the key intermediate *N2H on Mo edge sites of MoS2 and concurrently decreasing the reaction energy barrier. Meanwhile, MoS2/C3N4 rendered a more favorable *H adsorption free energy on S edge sites than on Mo edge sites of MoS2, thereby protecting the NRR-active Mo edge sites from the competing HER and leading to a high FE.
Biosorption, as a cost-effective technology for the removal of soluble heavy metals and organics from aqueous solutions, has been extensively studied, and most biosorption research mainly focused on ...the process isotherms, kinetics and thermodynamics. Thus, this paper attempted to offer a better understating of representative biosorption isotherms, kinetics and thermodynamics with special focuses on theoretical approaches for derivation of combined Langmuir–Freundlich isotherm as well as the pseudo-first- and second-order kinetic equations and general rate law equation for biosorption. Meanwhile, some potential problems encountered in biosorption research were also discussed.
For high‐energy lithium–sulfur batteries, the poor volumetric energy density is a bottleneck as compared with lithium–ion batteries, due to the low density of both the sulfur active material and ...sulfur host. Herein, in order to enhance the volumetric energy density of sulfur cathode, a universal approach is proposed to fabricate a compact sulfur cathode with dense materials as sulfur host, instead of the old‐fashioned lightweight carbon nanomaterials. Based on this strategy, heavy lanthanum strontium manganese oxide (La0.8Sr0.2MnO3), with a high theoretical density of up to 6.5 g cm−3, is introduced as sulfur host. Meanwhile, the La0.8Sr0.2MnO3 host also acts as an efficient electrocatalyst to accelerate the diffusion, adsorption, and redox dynamics of lithium polysulfides in the charge–discharge processes. As a result, such S/La0.8Sr0.2MnO3 cathode presents high gravimetric/volumetric capacity and outstanding cycling stability. Moreover, an ultra‐high volumetric energy density of 2727 Wh L−1‐cathode is achieved based on the densification effect with higher density (1.69 g cm−3), which is competitive to the Ni‐rich oxide cathode (1800–2160 Wh L−1) of lithium–ion batteries. The current study opens up a path for constructing high volumetric capacity sulfur cathode with heavy and catalytic host toward practical applications of lithium–sulfur batteries.
Heavy metal oxides are more suitable than light carbon materials to fabricate compact cathode for lithium–sulfur batteries. Specifically, lanthanum strontium manganese oxide nanofibers, with the tap density of 2.59 g cm−3, display efficient catalytic activity toward lithium polysulfides, enhancing the volumetric energy density of sulfur cathode, which can even exceed lithium–ion batteries.
•Current biological processes are challenged by high energy consumption.•Further optimization of biological processes cannot offer an ultimate solution.•Solutions toward energy self-sufficient ...biological processes need to be addressed.•Energy recovery should be maximized with minimized energy consumption.•Directions toward next-generation biological processes are outlined.
Almost all present biological processes for treating municipal wastewater have been developed based on the philosophy of biological oxidation with high energy consumption and generation of waste sludge. Given such a situation, the fundamental question of what are the possible ways towards energy self-sufficient biological reclamation of municipal wastewater needs to be addressed urgently. Therefore, this review aims to offer a critical view and a holistic analysis of biological treatment processes with the focus on energy self-sufficiency which indeed is a game changer in the future technology development. The way towards energy self-sufficient operation of biological processes is to maximize energy recovery, while to minimize energy consumption. The examples of such process configurations known as A-B processes are thus discussed. Consequently, this review may offer in-depth insights into the possible directions towards the next-generation biological processes for municipal wastewater reclamation which should be designed as a water-energy-resource factory.
Towards Understanding MCR-like Colistin Resistance Sun, Jian; Zhang, Huimin; Liu, Ya-Hong ...
Trends in microbiology (Regular ed.),
September 2018, 2018-09-00, 20180901, Letnik:
26, Številka:
9
Journal Article
Recenzirano
Antibiotic resistance has become a global public health priority. Polymyxins, a family of cationic polypeptide antibiotics, act as a final line of refuge against severe infections by Gram-negative ...pathogens with pan-drug resistance. Unfortunately, this last-resort antibiotic has been challenged by the emergence and global spread of mobilized colistin resistance determinants (mcr). Given the fact that it has triggered extensive concerns worldwide, we present here an updated view of MCR-like colistin resistance. These studies provide a basic framework for understanding the molecular epidemiology and resistance mechanism of MCR-like genes. However, further large-scale epidemiology and functional studies are urgently needed to better understand the biology of this clinically important antibiotic resistance.
Although natural resistance to polymyxin is rare, emergence and global distribution of the plasmid-borne mobilized colistin resistance gene (mcr-1) raises a great challenge to public health.
The discovery of MCR-1 and its variants represents a new mechanism for transferable resistance to polymyxin, a ‘last-resort’ refuge against superbugs with carbapenem resistance.
It seems likely that understanding the epidemiology of MCR-like genetic determinants will allow us to formulate efficient strategies (intervention and even elimination) to prevent acquired colistin resistance.
Structural dissection of full-length MCR-like enzymes provides clues for screening or designing small-molecule drugs targeting catalytic activity and phosphatidylethanolamine (PE) substrate-binding of the MCR-like enzyme to bypass colistin resistance.
PDF
