Rearrangement of Multiferroic BiFeO3 Nanodots Smaller than 15 nm Using Atomic Force Microscopy

In this study, we demonstrate an atomic force microscopy process for manipulating multiferroic BiFeO₃ nanodots smaller than 15 nm to desired positions on a Nb‐doped SrTiO₃ substrate. For formation of the BiFeO₃ nanodot array, nanocrystal movement was achieved using a +1.2 V biased conducting atomic force microscopy (CAFM) followed by nanocrystal attachment to the tip. Using this method, high‐density BiFeO₃ nanodot arrays with a density greater than 0.5 Tb/in.² can be achieved. Perfectly flipped ferroelectric polarization with an external electric field was observed for each BiFeO₃ nanodot, whose ferroelectric properties were confirmed using piezoelectric force microscopy.     

明式家具的丹麦知音

<正>即使在北欧人力费用极高的情况下,卡尔·汉森·桑仍以近乎苛刻的标准进行手工制作,并将这份永恒的经典和淡然的精致传递给全世界的使用者。丹麦设计界流传着这样一则故事:1807年,英国轰炸丹麦首都哥本哈根。时任丹麦国王下令从斯德哥尔摩南部到汉堡北部,用一切办法遍植橡树以躲避战争的创伤,并规定:"每棵树都不可被砍掉,除非新种一棵。"结果,战争的炮火并未殃及丹麦,这些橡树幸运存活了下来,年复一年,长成茂密森林。闻着木香,我们来到哥本哈根繁华都市的心脏处——自1780年起就开始引领丹麦设计与工艺时尚的Bredgade大街,百年品牌卡尔·汉森·桑(Carl Hansen&Son)全球旗舰店就坐落于此。     

Fast,Scalable Synthesis of Micronized Ge3N4@C with a High Tap Density for Excellent Lithium Storage

Nanostructuring has significantly contributed to alleviating the huge volume expansion problem of the Ge anodes. However, the practical use of nanostructured Ge anodes has been hindered due to several problems including a low tap density, poor scalability, and severe side reactions. Therefore, micrometer-sized Ge is desirable for practical use of Ge-based anode materials. Here, micronized Ge₃N₄ with a high tap density of 1.1 mg cm⁻² has been successfully developed via a scalable wet oxidation and a subsequent nitridation process of commercially available micrometer-sized Ge as the starting material. The micronized Ge₃N₄ shows much-suppressed volume expansion compared to micrometer-sized Ge. After the carbon coating process, a thin carbon layer (≈3 nm) is uniformly coated on the micronized Ge₃N₄, which significantly improves electrical conductivity. As a result, micronized Ge₃N₄@C shows high reversible capacity of 924 mAh g⁻¹ (2.1 mAh cm⁻²) with high mass loading of 3.5 mg cm⁻² and retains 91% of initial capacity after 300 cycles at a rate of 0.5 C. Additionally, the effectiveness of Ge₃N₄@C as practical anodes is comprehensively demonstrated for the full cell, showing stable cycle retention and especially excellent rate capability, retaining 47% of its initial capacity at 0.2 C for 12 min discharge/charge condition.     

Pd coated one-dimensional Ag nanostructures: Controllable architecture and their electrocatalytic performance for ethanol oxidation in alkaline media

One-dimensional (1D) metal-coated Pd structures are efficient catalysts for the ethanol electro-oxidation and promising strategy for minimizing the Pd-loading toward commercialization of direct ethanol fuel cells (DEFCs). Herein, the decorated and core-shell architectures of a novel Pd coating on Ag nanowires (PdAg-NWs) are controllable by a two-step polyol method based on the galvanic replacement reaction. The integration of uniform shell with a low Pd concentration and partial hollow structure onto 1D PdAg-NWs exhibits the highest efficiency for ethanol oxidation reaction (EOR) in alkaline solution. In comparison with Pd nanoparticles (PdNPs/C), the PdAgNWs/C performes 11 times superior EOR activity, and the onset potential shifts 80 mV negatively. The presence of Ag in PdAg-NWs enhances the absorption capacity of ethanol molecules and hydroxyl ions on the active sites, and improves the catalyst tolerance to CO-like intermediates, making them a potential anodic catalyst for DEFCs.     

Conductive adhesive with transient liquid‐phase sintering technology for high‐power device applications

A highly reliable conductive adhesive obtained by transient liquid‐phase sintering (TLPS) technologies is studied for use in high‐power device packaging. TLPS involves the low‐temperature reaction of a low‐melting metal or alloy with a high‐melting metal or alloy to form a reacted metal matrix. For a TLPS material (consisting of Ag‐coated Cu, a Sn96.5‐Ag3.0‐Cu0.5 solder, and a volatile fluxing resin) used herein, the melting temperature of the metal matrix exceeds the bonding temperature. After bonding of the TLPS material, a unique melting peak of TLPS is observed at 356 °C, consistent with the transient behavior of Ag₃Sn + Cu₆Sn₅ → liquid + Cu₃Sn reported by the National Institute of Standards and Technology. The TLPS material shows superior thermal conductivity as compared with other commercially available Ag pastes under the same specimen preparation conditions. In conclusion, the TLPS material can be a promising candidate for a highly reliable conductive adhesive in power device packaging because remelting of the SAC305 solder, which is widely used in conventional power modules, is not observed.     

Silver metallization for microwave device using aerosol deposition

We examined the possibility of using aerosol deposition (AD) as a simple, environmentally friendly and dry metallization process capable of acting as an alternative to the electroless and electroplating methods. Silver thick films were fabricated, their characteristics evaluated, and the factors influencing their growth investigated. As a result, silver thick films were successfully fabricated by AD with high deposition rates (10 μm/min) at room temperature. The resistivity of the as-deposited silver thick films was 8–10 times larger than that of the bulk silver. Post-annealing increased the resistivity of the silver films by approximately 2–3 times compared to that of the bulk silver. Microstructural observations revealed an increase in the connectivity between the silver particles after the heat treatments, which reduced the resistivity of the as-deposited silver films.     

Short communication: Development of a direct in vivo screening model to identify potential probiotic bacteria using Caenorhabditis elegans

Caenorhabditis elegans is an accepted model host to study host-bacteria interactions in the gut, in addition to being a simple model with which to study conserved aspects of biological signaling pathways in intestinal environments, because these nematode worms have similar intestinal cells to those of humans. Here, we used C. elegans to develop a new in vivo screening system for potential probiotic lactic acid bacteria (LAB). Initially, critical colonization ability of LAB strains isolated from Korean infant feces was screened in the worm intestinal tract over a period of 5 d. Furthermore, we investigated host health-promoting activities, including longevity-extending effects and immune-enhancing activities against foodborne pathogen infection. We identified 4 LAB strains that were highly persistent in the nematode gut and that significantly prolonged the longevity of C. elegans and improved the survival of C. elegans in response to infection by Staphylococcus aureus. The 4 LAB strains we identified showed resistance to acid and bile conditions, assimilated cholesterol, and were able to attach to a mucus layer. The 4 LAB isolates were identified as Lactobacillus plantarum using 16S rRNA sequencing analysis. Taken together, we developed a direct in vivo screening system using C. elegans to study host health-promoting LAB. Our system is simple, rapid, cost-effective, and reliable, and we anticipate that this system will result in the discovery of many more potential probiotic bacteria for dairy foods.