Ordered mesoporous SiO₂ nanoparticles as charge storage sites for enhanced triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) have demonstrated great prospects in energy harvesting and self-powered sensing. However, the surface triboelectric charges are very easy to dissipate in the air atmosphere, especially after the contact electrification stops. Here, we propose ordered mesoporous SiO2 (OMS) nanoparticles with a large specific surface area (SSA) as effective body charge storage sites inside polydimethylsiloxane (OMS-PDMS) to enhance the output performance of TENGs. With the addition of 1 wt% OMS nanoparticles, the transferred charges of the TENG showed a sharp enhancement, rising from 21 nC to 60 nC. The enhancement effect of OMS nanoparticles on the output increased linearly with SSA. In addition, the OMS-PDMS also demonstrated a superior charge retention ability, with 68 % of the voltage being retained over a long time after the contact separation motion stopped, while that of the pure PDMS quickly dropped to near zero. The instantaneous output power density of the TENG with OMS-PDMS reached 5.26 W/m2, which is a 25-fold enhancement. This work proposed OMS nanoparticles with a large SSA as effective charge storage sites to enhance the output performance of TENGs.</p

Status and perspectives of hierarchical porous carbon materials in terms of high-performance lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries, although a promising candidate of next-generation energy storage devices, are hindered by some bottlenecks in their roadmap toward commercialization. The key challenges include solving the issues such as low utilization of active materials, poor cyclic stability, poor rate performance, and unsatisfactory Coulombic efficiency due to the inherent poor electrical and ionic conductivity of sulfur and its discharged products (e.g., Li2S2 and Li2S), dissolution and migration of polysulfide ions in the electrolyte, unstable solid electrolyte interphase and dendritic growth on anodes, and volume change in both cathodes and anodes. Owing to the high specific surface area, pore volume, low density, good chemical stability, and particularly multimodal pore sizes, hierarchical porous carbon (HPC) materials have received considerable attention for circumventing the above problems in Li–S batteries. Herein, recent progress made in the synthetic methods and deployment of HPC materials for various components including sulfur cathodes, separators and interlayers, and lithium anodes in Li–S batteries is presented and summarized. More importantly, the correlation between the structures (pore volume, specific surface area, degree of pores, and heteroatom-doping) of HPC and the electrochemical performances of Li–S batteries is elaborated. Finally, a discussion on the challenges and future perspectives associated with HPCs for Li–S batteries is provided

Enhanced triboelectric nanogenerators based on 2D smectite clay nanosheets with a strong intrinsic negative surface charge

Triboelectric nanogenerators (TENGs) have demonstrated their huge potential in micro/nano energy harvesting for self-powered systems. The output performance of TENGs is largely dependent on the surface charge density of the triboelectric materials. Here, for the first time, we propose 2D smectite clay (SC) nanosheets with a strong intrinsic negative surface charge for improving the charge density of traditional triboelectric-negative materials. A single-layer 2D SC nanosheet (∼1.1 nm thick) showed a strong negative surface potential (−14.3 mV), and the SC was confirmed to have a strong triboelectric negativity close to that of polytetrafluoroethylene (PTFE). 2D SC nanosheets were blended into polyvinylidene fluoride (SC-PVDF), based on which the SC-TENG demonstrated a significantly enhanced output performance, with the transferred charge increasing from 14 nC to 35 nC at the optimal SC concentration of 5 wt%. At higher SC concentrations, the influence of decreased effective contact area because of severe aggregation of SC nanosheets began to outperform the effect of increased interior charge. The instantaneous output power density of the SC-TENG was enormously improved to 1450 mW/m2 from that of the pristine TENG (15 mW/m2). This work proposed a new 2D material, SC, with a strong intrinsic negative surface charge, which has huge prospects in enhancing the output performance of TENGs.</p

Cystatin C and risk of new-onset depressive symptoms among individuals with a normal creatinine-based estimated glomerular filtration rate: A prospective cohort study

The association between cystatin C and depressive symptoms in the general population has not been thoroughly elucidated to date. We investigated the association of cystatin C with new-onset depressive symptoms among individuals with normal creatinine-based estimated glomerular filtration rates (eGFR). In the China Health and Retirement Longitudinal Study, 5111 participants without depressive symptoms or renal dysfunction (eGFR \u3c 60 ml/min/1.73

Nitrogen-doped porous carbon nanofibers embedded with Cu/Cu₃P heterostructures as multifunctional current collectors for stabilizing lithium anodes in lithium-sulfur batteries

Among the various beyond-lithium-ion battery systems, lithium-sulfur batteries (Li-S) have been widely considered as one of the most promising technologies owing to their high theoretical energy density. However, the irregular Li plating/stripping and infinite volume change associated with low Coulombic efficiency and safety concerns of host-less lithium anode hinder the practical application of Li-S batteries. Herein, Cu/Cu3P heterostructure-embedded in carbon nanofibers (Cu/Cu3P-N-CNFs) are developed as multifunctional current collectors for regular lithium deposition. The 3D porous interconnected carbon skeleton endows effectively reduced local current density and volume expansion, meanwhile the Cu/Cu3P particles function as nucleation sites for uniform lithium plating. Consequently, the developed ion/electron-conducting skeleton delivers remarkable electrochemical performances in terms of high Coulombic efficiency for 500 cycles at 1 mA cm−2, and the accordingly symmetric cell exhibits long-term cyclic duration over 1500 h with a low voltage hysteresis of ∼ 80 mV at 1 mA cm−2. Moreover, Li-S full cells paired with the developed anode and S@CNTs cathode also show superior rate capability (568 mAh/g at 2C) and excellent stability of &gt;500 cycles at 0.2C, further demonstrating the great potential of Cu/Cu3P-N-CNFs as promising current collectors for advanced lithium-metal batteries.</p

Concurrent Modified Constant Modulus Algorithm and Decision Directed Scheme With Barzilai-Borwein Method

At present, in robot technology, remote control of robot is realized by wireless communication technology, and data anti-interference in wireless channel becomes a very important part. Any wireless communication system has an inherent multi-path propagation problem, which leads to the expansion of generated symbols on a time scale, resulting in symbol overlap and Inter-symbol Interference (ISI). ISI in the signal must be removed and the signal restores to its original state at the time of transmission or becomes as close to it as possible. Blind equalization is a popular equalization method for recovering transmitted symbols of superimposed noise without any pilot signal. In this work, we propose a concurrent modified constant modulus algorithm (MCMA) and the decision-directed scheme (DDS) with the Barzilai-Borwein (BB) method for the purpose of blind equalization of wireless communications systems (WCS). The BB method, which is two-step gradient method, has been widely employed to solve multidimensional unconstrained optimization problems. Considering the similarity of equalization process and optimization process, the proposed algorithm combines existing blind equalization algorithm and Barzilai-Borwein method, and concurrently operates a MCMA equalizer and a DD equalizer. After that, it modifies the DD equalizer's step size (SS) by the BB method. Theoretical investigation was involved and it demonstrated rapid convergence and improved equalization performance of the proposed algorithm compared with the original one. Additionally, the simulation results were consistent with the proposed technique

Structural Alterations from Multiple Displacement Amplification of a Human Genome Revealed by Mate-Pair Sequencing

Comprehensive identification of the acquired mutations that cause common cancers will require genomic analyses of large sets of tumor samples. Typically, the tissue material available from tumor specimens is limited, which creates a demand for accurate template amplification. We therefore evaluated whether phi29-mediated whole genome amplification introduces false positive structural mutations by massive mate-pair sequencing of a normal human genome before and after such amplification. Multiple displacement amplification led to a decrease in clone coverage and an increase by two orders of magnitude in the prevalence of inversions, but did not increase the prevalence of translocations. While multiple strand displacement amplification may find uses in translocation analyses, it is likely that alternative amplification strategies need to be developed to meet the demands of cancer genomics