Optimizing interplanar spacing, oxygen vacancies and micromorphology via lithium-ion pre-insertion into ammonium vanadate nanosheets for advanced cathodes in aqueous zinc-ion batteries

Ammonium vanadates, featuring an N─H···O hydrogen bond network structure between NH4+ and V─O layers, have become popular cathode materials for aqueous zinc-ion batteries (AZIBs). Their appeal lies in their multi-electron transfer, high specific capacity, and facile synthesis. However, a major drawback arises as Zn2+ ions tend to form bonds with electronegative oxygen atoms between V─O layers during cycling, leading to irreversible structural collapse. Herein, Li+ pre-insertion into the intermediate layer of NH4V4O10 is proposed to enhance the electrochemical activity of ammonium vanadate cathodes for AZIBs, which extends the interlayer distance of NH4V4O10 to 9.8 Å and offers large interlaminar channels for Zn2+ (de)intercalation. Moreover, Li+ intercalation weakens the crystallinity, transforms the micromorphology from non-nanostructured strips to ultrathin nanosheets, and increases the level of oxygen defects, thus exposing more active sites for ion and electron transport, facilitating electrolyte penetration, and improving electrochemical kinetics of electrode. In addition, the introduction of Li+ significantly reduces the bandgap by 0.18 eV, enhancing electron transfer in redox reactions. Leveraging these unique advantages, the Li+ pre-intercalated NH4V4O10 cathode exhibits a high reversible capacity of 486.1 mAh g−1 at 0.5 A g−1 and an impressive capacity retention rate of 72% after 5,000 cycles at 5 A g−1

Synthesis and Acoustic Study of a New Tung Oil-Based Polyurethane Composite Foam with the Addition of Miscanthus Lutarioriparius

Polyurethane foam is commonly used in the automobile industry due to its favorable acoustic performances. In this study, a new tung oil-based polyurethane composite foam (TOPUF) was prepared by a one-step method. Different forms and contents of miscanthus lutarioriparius (ML) were used in TOPUF for improving acoustic performance. Polyurethane foams were characterized by means of Fourier transform infrared and SEM. The acoustic properties and mechanical properties of TOPUF, obtained with ML, were determined and compared with pure petroleum-based polyurethane foam. The results illustrate that the modification of TOPUF with the ML has a positive effect on the acoustic and mechanical properties in comparison to the unmodified foam. TOPUF obtained with ML powders has better acoustic performance than that obtained with ML strips. The optimum acoustic performance is achieved at the filler content of 0.3 wt%. The average sound absorption coefficient and transmission loss can reach 0.518, and 19.05 dB, respectively

Automatic Speech Recognition Performance Improvement for Mandarin Based on Optimizing Gain Control Strategy

Automatic speech recognition (ASR) is an essential technique of human–computer interactions; gain control is a commonly used operation in ASR. However, inappropriate gain control strategies can lead to an increase in the word error rate (WER) of ASR. As there is a current lack of sufficient theoretical analyses and proof of the relationship between gain control and WER, various unconstrained gain control strategies have been adopted on realistic ASR systems, and the optimal gain control with respect to the lowest WER, is rarely achieved. A gain control strategy named maximized original signal transmission (MOST) is proposed in this study to minimize the adverse impact of gain control on ASR systems. First, by modeling the gain control strategy, the quantitative relationship between the gain control strategy and the ASR performance was established using the noise figure index. Second, through an analysis of the quantitative relationship, an optimal MOST gain control strategy with minimal performance degradation was theoretically deduced. Finally, comprehensive comparative experiments on a Mandarin dataset show that the proposed MOST gain control strategy can significantly reduce the WER of the experimental ASR system, with a 10% mean absolute WER reduction at −9 dB gain

Automatic Speech Recognition Performance Improvement for Mandarin Based on Optimizing Gain Control Strategy

Automatic speech recognition (ASR) is an essential technique of human–computer interactions; gain control is a commonly used operation in ASR. However, inappropriate gain control strategies can lead to an increase in the word error rate (WER) of ASR. As there is a current lack of sufficient theoretical analyses and proof of the relationship between gain control and WER, various unconstrained gain control strategies have been adopted on realistic ASR systems, and the optimal gain control with respect to the lowest WER, is rarely achieved. A gain control strategy named maximized original signal transmission (MOST) is proposed in this study to minimize the adverse impact of gain control on ASR systems. First, by modeling the gain control strategy, the quantitative relationship between the gain control strategy and the ASR performance was established using the noise figure index. Second, through an analysis of the quantitative relationship, an optimal MOST gain control strategy with minimal performance degradation was theoretically deduced. Finally, comprehensive comparative experiments on a Mandarin dataset show that the proposed MOST gain control strategy can significantly reduce the WER of the experimental ASR system, with a 10% mean absolute WER reduction at −9 dB gain

Does exercise-induced apelin affect sarcopenia? A systematic review and meta-analysis

Purpose/objective There have been a number of studies on the role of the novel protein apelin, identified in 1998, in improving muscular function and structure in various human organs, as well as on how it is involved in pathological processes. The aim of this systematic review and meta-analysis was to determine the effect of exercise on serum apelin levels to provide up-to-date data for the development of an exercise intervention for older adults. Methods We searched for articles in PubMed, Ovid MEDLINE, and EMBASE from database inception to May 31, 2019. To conduct a meta-analysis of the primary outcome (serum apelin level), we analyzed intervention effect sizes of the differences between the exercise group and control groups for the primary outcome measure at post-treatment. The outcomes were analyzed using Hedge's statistic effect size (Zr) for weight mean difference (WMD) from various statistical results, including t, F, x(2), and r. A heterogeneity test was conducted using Higgin's I-2 statistic and Q statistics (p > 0.10) via a forest plot. A fixed-effect model was considered if Higgin's I-2 was less than 50%. If heterogeneity was high (I-2 > 50%), a random-effects model with a subgroup analysis or meta-regression was used. A meta-analysis using nine studies showed that exercise could increase serum apelin levels, which was beneficial for such metabolic diseases as diabetes. Results In the subgroup analysis, the 50-60-year-old group showed significant effects of exercise. However, the BMI (normal, overweight, and obesity) categories failed to show any difference in exercise-induced effect. Conclusion Further studies are needed to clarify in greater detail the effect of resistance exercise on apelin levels, including data on frequency, type, intensity, and time of aerobic exercise, to compare their effects on sarcopenia and cognitive disorders.N

Diatom composition and fluxes over the Northwind Ridge, western Arctic Ocean: impact of marine surface circulation and sea ice distribution

International audienceOver the last decades, the western Arctic Ocean has undergone unprecedented environmental changes. However, long-term in situ observations of marine phytoplankton are still rare and therefore insufficient to fully characterize their evolutionary trends. This study investigated the diatom fluxes and composition in sediment trap material collected from the Northwind Ridge, western Arctic Ocean, from August 2008 to September 2009. Our data showed that Chaetoceros resting spores were the predominant species, accounting for >40% of the diatom composition. The sea ice diatom group, which included Fossula arctica, Fragilariopsis cylindrus and F. oceanica, dominated the rest of the assemblage throughout the observation period. While diatom fluxes in winter were extremely low, higher flux values were found in summer, and summer 2009 flux values were twice as high as those in 2008. The high total mass and diatom fluxes in summer 2009 were attributed to the combined effect of a weakened Beaufort Gyre, a strengthened Pacific water inflow (PWI) and the distribution pattern of the sea ice. The higher levels of coastal diatoms and terrigenous proxies in summer 2009 were consistent with the intensified PWI. Sea ice diatoms and sea ice biomarker IP25 fluxes were both high during the sea ice melting season and were significantly correlated with each other (r2 = 0.64, p < 0.01). Our data also suggest that sea ice diatoms are prone to selective dissolution in the water column and sediments, implying the existence of biases in diatom assemblage data and subsequently in paleoceanographic reconstructions