No abstract

As an effective means to improve quality of life and prevent diseases, the demand for probiotics and related products has increased in recent years. However, it is still unclear whether a particular probiotic strain will have similar beneficial effects on healthy adults from different regions. In this study, the probiotic Lactobacillus casei Zhang (LCZ) was consumed by healthy adults from six different Asian regions and the changes in gut microbiota were compared using PacBio single molecule, real-time (SMRT) sequencing technology based on samples collected before, during and after consumption of LCZ. Our results reveal that the effect of LCZ consumption on individuals was closely related to the composition of that individual’s basal gut microbiota. A Gut Microbiota Variability Index (GMVI) was proposed to quantitatively compare the effects of LCZ on human gut microecology. Subjects from Xinjiang and Singapore regions had the highest and lowest GMVI, respectively. In general, consumption of LCZ increased the relative abundance of certain beneficial bacteria such as Lactobacillus, Roseburia, Coprococcus and Eubacterium rectale , while it inhibited growth of certain harmful bacteria such as Blautia and Ralstonia pickettii . In addition, consumption of LCZ was responsible for the conversion of some participants from Prevotella copri/Faecalibacterium prausnitzii (PF) enterotype to Faecalibacterium prausnitzii/Bacteroides dorei (FB) enterotype and consistently increased the abundance of lactic acid bacteria in the gut. It also increased/enhanced phosphate metabolic modules, amino acid transport systems, and isoleucine biosynthesis, but conversely decreased lipopolysaccharide biosynthesis. These changes could have health benefits for healthy adults.

Hierarchical, three-fold symmetrical dendritic gold was prepared in an aqueous solution of the quaternary ammonium cationic surfactant dodecyltrimethylammonium bromide (DTAB). Similar surfactants with different head groups and hydrocarbon chain lengths were also used for comparison. Two-fold and one-fold symmetrical dendritic gold nanostructures were obtained in N-dodecyl-N-methylpyrrolidinium bromide (C(12)-MPB) and dodecyltriethylammonium bromide (DTEAB) aqueous solutions, respectively. Longer hydrocarbon chain lengths were unfavorable for the formation of dendritic nanostructures. The interaction energies between the individual surfactants and Au (111) plane were calculated using molecular dynamics simulations. Based on a series of contrast experiments and molecular dynamics simulations, the possible growth mechanism and fabrication process of the dendritic structures were proposed. The DTAB-capped, three-fold gold dendrites exhibited good surface-enhanced Raman scattering (SERS) sensitivity toward rhodamine 6G (R6G), indicating their potential for use in SERS-based detections and analysis. This work provides a simple and effective strategy for fabricating dendritic gold nanostructures in aqueous solutions.

No abstract

using artificial synapses is an essential step to accomplish the neuromorphic computing system. [9,10] Formerly, artificial synapses were realized by complementary metal-oxide-semiconductor (CMOS) circuitry containing dozens of electronic components. [11] However, many electronic components result in complicated architecture and high energy consumption. As comparison, two-terminal memristors, especially resistive random access memory and phase change random access memory, that recently entered our field of vision have been widely discussed as artificial synapses owing to their structures which is similar to that of synapses and the reproducible tuning of resistance. [12][13][14][15][16] Also, for an ideal synapse device it is better to meet these requirements, such as symmetric potentiation-depression characteristics, 5-bit/cell analog levels, and high non-volatility with ≈100 conductance ON/OFF ratio. They are the key points we need to take into account. [17,18] In particular, HfO 2 -based memristors have been demonstrated as a leading alternative as synapse in virtue of its distinctive superiority, such as simple structure, <10 ns switching speed, <10 pJ power consumption, multilevel ability, and compatibility with CMOS fabrication process. [19][20][21] However, the resistance contrast (ON/OFF ratio) of HfO 2 -based memristors ranges from ≈40 to ≈150. [22] Considering the resistance fluctuation of these memristors across a silicon wafer, larger ON/OFF ratio is needed to guarantee high recognition accuracy (>97%). [23] Recently, several works were reported on improvement of the memristors' performance with thin interfacial layer. [24][25][26] As one of the most important multiferroic materials, bismuth iron oxide with perovskite structure has come into notice for its potential in multifunctional device applications. [27] Moreover, BiFeO 3 (BFO) has attracted much attention because it possesses superior characteristics of resistance switching (RS) such as large ON/OFF ratio in some researches. [28] It is also confirmed that BFO can be applied in bi-layer design memristor to significantly improve RS characteristics, [29] which gives inspiration to insert BFO thin film as the goal of high device performances.In this work, ultrathin BFO film was inserted to fabricate Pt/BFO/HfO 2 /TiN memristor to improve the RS characteristic of HfO 2 -based memristor. The material characterization and RS behavior were systemically analyzed. The role of the inserting BFO layer on the RS behavior was evaluated and the RS mechanism triggered by inserting BFO film was explored.HfO 2 -based memristors that remembers the history of the current that has passed through them have attracted great interest for use as artificial synapses in neuromorphic systems. However, the low resistance contrast exhibited by HfO 2 -based memristors seriously decreases their recognition accuracy. By inserting a 2 nm BiFeO 3 layer a large memory window of 10 4 and remarkable pulse endurance of 10 8 cycles are achieved. Multilevel storage capability is also d...