Heuristic Clustering Based on Centroid Learning and Cognitive Feature Capturing

As one of the typical clustering algorithms, heuristic clustering is characterized by its flexibility in feature integration. This paper proposes a type of heuristic algorithm based on cognitive feature integration. The proposed algorithm employs nonparameter density estimation and maximum likelihood estimation to integrate whole and local cognitive features and finally outputs satisfying clustering results. The new approach possesses great expansibility, which enables priors supplement and misclassification adjusting during clustering process. The advantages of the new approach are as follows: (1) it is effective in recognizing stable clustering results without priors given in advance; (2) it can be applied in complex data sets and is not restricted by density and shape of the clusters; and (3) it is effective in noise and outlier recognition, which does not need elimination of noises and outliers in advance. The experiments on synthetic and real data sets exhibit better performance of the new algorithm

Abundance and Diversity of Several Bacterial Genera in the Mariculture Environment

Although there have been some studies on pathogenic bacteria and their pathogenicity in animals, few studies have assessed the effects of aquaculture on the diversity of potentially pathogenic bacteria. This study used Illumina sequencing and quantitative PCR to explore the diversity of several bacterial genera containing pathogenic bacteria in the mariculture environment and the intestines of different cultured animals. These bacterial genera can be divided into two categories: The first category (14 genera) had high abundances and a low coefficient of variation among similar samples were significantly correlated with the total number of bacteria (r2 > 0.7, p ≈ 0). The other category (7 genera) with low abundances and a high coefficient of variation had no significant relationship with bacterial abundance. These results indicated that these bacterial genera had different responses and adaptation mechanisms to the aquaculture environment. Principal component analysis (PCA) showed that a high abundance of genera was closely related to the pond environment. The abundance of these bacterial genera in the animals’ intestines was much higher than source water, especially for Mycoplasma, Pseudoalteromonas, Vibrio, and Enterococcus, suggesting the aquaculture promoted the high abundance of these bacteria. This study provides a theoretical basis for sediment-associated pathogens acting as a potential pathogen source in the aquaculture environment. This study provides a strategy for disease prevention and control according to the characteristics of potential pathogens in the cultural process

On the Effect of Modifications to Montmorillonite for the Desulphurization of Synthetic Gasoline

The preparation, characterization and desulphurization of hexadecyltrimethylammonium bromide (CTAB)-intercalated montmorillonite (CTAB-MMT) and SiO 2 Ce-pillared montmorillonite (SiO 2 Ce-MMT) is described. CTAB-MMT, SiO 2 Ce-MMT and MMT (the original clay) were examined for their ability to remove thiophene sulphur from normal heptane solution as well as from synthetic gasoline. The adsorption thermodynamics and kinetics on all three adsorbents were investigated when it was found that SiO 2 Ce-MMT possessed a higher adsorption capacity than MMT and CTAB-MMT. The adsorption capacity increased as the temperature increased in the range 303–333 K. The data for the adsorption equilibrium were well fitted by the Freundlich isotherm model. Negative values of ΔG 0 suggested that the adsorption process was spontaneous. Furthermore, positive ΔH 0 and ΔS 0 values indicated that the adsorption was endothermic and irreversible

Fe-doped and sulfur-enriched Ni3S2 nanowires with enhanced reaction kinetics for boosting water oxidation

Exploring cost-effective and highly-active oxygen evolution reaction (OER) electrocatalysts is a pressing task to propel water electrolysis for green hydrogen production. Herein, we constructed a class of Fe-doped and S-enriched Ni3S2 nanowires electrocatalysts for optimizing the target intermediates adsorption to decrease the OER overpotentials at various current densities. The optimal Ni3S2-1.4%Fe electrocatalyst possesses the most active sites and exhibits an ultralow overpotential of 190 mV at 10 mA cm−2 with an excellent stability of > 60 h, exceeding the majority of recently-reported Ni3S2-based electrocatalysts. The trivalence Fe-doping not only reduces the electron density of the Ni center, but also enables the sulfur enrichment on the Ni3S2 surface, which greatly improves the intrinsic activity and the number of target intermediates (∗OOH). A novel methanol-assisted electrochemical evaluation further reveals that the Ni3S2-1.4%Fe electrocatalyst demonstrates a weaker binding ability to ∗OH with the rapid generation of ∗OOH species, and thus gives a lower apparent activation energy compared with the surface sulfur reduced ones. This work provides a new perspective for regulating the adsorption of intermediates through doping strategy

Engineering Se/N co-doped hard CNTs with localized electron configuration for superior potassium storage

The earth-abundant hard carbons have drawn great concentration as potassium-ion batteries (KIBs) anode materials because of their richer K-storage sites and wider interlayer distance versus graphite, but suffer from a low electrochemical reversibility. Herein, the novel Se/N co-doped hard-carbon nanotubes (h-CNTs) with localized electron configuration are demonstrated by creating unique N-Se-C covalent bonds stemmed from the precise doping of Se atoms into carbon edges and the subsequent bonding with pyrrole-N. The strong electron-donating ability of Se atoms on d-orbital provides abundant free electrons to effectively relieve charge polarization of pyrrole-N-C bonds, which contributes to balance the K-ion adsorption/desorption, therefore greatly boosting reversible K-ion storage capacity. After filtering into self-standing anodes with weights of 1.5–12.4 mg cm−2, all of them deliver a high reversible gravimetric capacity of 341 ± 4 mAh g−1 at 0.2 A g−1 and a linear increasing areal capacity to 4.06 mAh cm−2. The self-standing anode can still maintain 209 mAh g−1 at 8.0 A g−1 (93.3% retention) for a long period of 2000 cycles with a constant Se/N content. © 2022 Wiley-VCH GmbH.National Natural Science Foundation of China, NSFC: 21975074, 22208102; Shanghai Municipal Education Commission; Fundamental Research Funds for the Central Universities: 22220171800

Tailorable surface sulfur chemistry of mesoporous Ni3S2 particles for efficient oxygen evolution

Boosting the intrinsic activity of electrocatalysts is pivotal in enhancing the oxygen evolution reaction (OER) at the source. Herein, we synthesize a mesoporous Ni 3 S 2 particle electrocatalyst on Ni foam that has appropriate surface sulfur chemistry and demonstrates excellent catalytic activity as well as rapid reaction kinetics. The optimized Ni 3 S 2 electrocatalyst shows ultralow overpotentials of 213 and 283 mV at 10 and 100 mA cm −2 , respectively, with a very low Tafel slope of 45 mV dec −1 in alkaline media. The ECSA normalized current density is 1.1 mA cm −2 at an overpotential of 270 mV, nearly three times higher than that of pristine Ni 3 S 2 (0.4 mA cm −2 ). It has been observed that the sulfur-engineered Ni 3 S 2 electrocatalyst can promote more Ni 3+ generation with a significant shift of the Ni center binding energy compared with pristine Ni 3 S 2 during the OER. The findings propose a facile tactic to improve the intrinsic OER activity for water splitting by optimizing the surface sulfur chemistry of metal sulfide-based electrocatalysts. © The Royal Society of Chemistry.National Natural Science Foundation of China [21838003, 21808061, 91534122]; Social Development Program of Shanghai [17DZ1200900]; Shanghai Scientific and Technological Innovation Project [18JC1410600, 18DZ2252400]; Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning; Fundamental Research Funds for the Central Universities [222201718002

Confined Synthesis of FeS₂ Nanoparticles Encapsulated in Carbon Nanotube Hybrids for Ultrastable Lithium-Ion Batteries

To address the large volume change and polysulfide dissolution of FeS₂-based materials for lithium-ion batteries (LIBs), we demonstrate the synthesis of FeS₂ nanoparticles encapsulated in carbon nanotubes (CNTs) by a confined reaction. There is sufficient void space between adjacent FeS₂ nanoparticles for guaranteeing the highly structural integrity. The resultant FeS₂/CNT hybrids, when served as anode materials for LIBs, predictably exhibit a very stable capacity retention of 800 mAh g^–1 over 200 cycles at 200 mA g^–1. Even at 2000 mA g^–1, they still deliver high-rate and long-life performance with a high specific capacity of 525 mAh g^–1 after 1000 cycles. Such a kind of encapsulated structure is helpful for enhancing rate capability and cycling stability in LIBs applications. Importantly, the present confined reaction strategy can be extensively applied to synthesize other analogous hybrids for energy storage and conversion

Observation of the second-order magnetic and reentrant spin-glass transitions in LiNi0.5Mn0.5O2LiNi_{0.5}Mn_{0.5}O_{2}

The structure and magnetic properties of LiNi0.5Mn0.5O2 were studied by synchrotron X-ray diffraction, dcand ac susceptibilities. The material showed a continuous magnetic transition from paramagnetism intoferrimagnetism, followed by a spin glass with the decrease of temperature. Using a criterion given byBanerjee to distinguish first-order magnetic transition from second-order ones, it is shown that the ferrimagnetictransition at 108 K belongs to the second-order type. The frequency dependence of peakintensity and the shift in ac susceptibility at 14 K suggest a reentrant spin glass transition inLiNi0.5Mn0.5O2