Stability of M13 Phage in Organic Solvents

The effect of different types of organic solvents on the structural integrity of M13 phages has been directly visualized by transmission and scanning electron microscopy. The exposure of M13 phages to apolar hexane had no effect on the structure of the phages for up to 8 h. In contrast, phages showed ~10-fold contraction into rod-like I-forms and to flattened spheroids with ~12 nm diameter upon exposure to polar organic solvents. We show that this finding can be beneficial for the macromolecular self-assembly and in broader aspects, to enhance the spatial arrangement of desired inorganic nanoparticles in the rapidly developing field of virotronics.

跃变比判别热解Si-C-N陶瓷EELS定量分析的有效性

电子能量损失谱(EELS)分析方法的运用为材料研究领域提供了有力的定性和定量手段。通过对内壳层电子激发谱跃变比的计算,能够获得样品相对厚度的参考信息。这一方法弥补了实验条件在同步采集等离子激发谱和内壳层电子激发谱方面的局限性,并为辨别EELS定量的可靠性提供依据。本文以Si3N4为例,对跃变比随样品相对厚度的变化规律进行了研究,并在低于最佳样品厚度的范围内得到了可靠的定量结果。类似的跃变比变化规律能够运用于成份均一的Si-C-N热解样品,然而对于非均一的Si-C-N退火样品则不适用。

Enhanced Pseudo‑Capacitive Contributions to High‑Performance Sodium Storage in TiO2/C Nanofibers via Double Effects of Sulfur Modification

Pseudo-capacitive mechanisms can provide higher energy densities than electrical double-layer capacitors while being faster than bulk storage mechanisms.Usually,they suffer from low intrinsic electronic and ion conductivities of the active materials.Here,taking advantage of the combination of TiS2 decoration,sulfur doping,and a nanometer-sized structure,as-spun TiO2/C nanofiber composites are developed that enable rapid transport of sodium ions and electrons,and exhibit enhanced pseudo-capacitively dominated capacities.At a scan rate of 0.5 mV s−1,a high pseudo-capacitive contribution(76%of the total storage)is obtained for the S-doped TiS2/TiO2/C electrode(termed as TiS2/S-TiO2/C).Such enhanced pseudocapacitive activity allows rapid chemical kinetics and significantly improves the high-rate sodium storage performance of TiO2.The TiS2/S-TiO2/C composite electrode delivers a high capacity of 114 mAh g−1 at a current density of 5000 mA g−1.The capacity maintains at high level(161 mAh g−1)even after 1500 cycles and is still characterized by 58 mAh g−1 at the extreme condition of 10,000 mA g−1 after 10,000 cycles.

Biomineralization of Zinc-Phosphate-Based Nano Needles by Living Microalgae

Up to now, chemical synthesis routes only provide restricted opportunities for the formation of structured nano particles. In contrast, living microorganisms generate nano materials of well defined shapes by the precise control of biomineralization. Here we reveal new principles for the generation of functional nano materials through the process of biomineralization. We used the detoxification mechanism of the unicellular alga Scenedesmus obliquus to generate a techno logically interesting zinc-phosphate-based nano material. The algae were incubated in media with a sublethal zinc concentration (6.53 mg Zn dm-3) for 4 weeks. Using BF-and ADF-STEM imaging combined with analytical XEDS we could show that nano needles containing phosphorus and zinc were formed inside the living cells. Further more, the cells incubated with zinc show a strong fluorescence. Our findings indicate that the algae used polyphosphate bodies for detoxification of the zinc ions, leading to the generation of intracellular zinc-phosphate-based nano needles. Beside the technological application of this material, the fluorescent cells can be used for labeling of e.g. biological probes. This new experimental protocol for the production of an inorganic functional material can be applied also for other substances.

Initial nucleation of amorphous Si–B–C–N ceramics derived from polymer-precursors

Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved electron energy-loss spectroscopy(EELS) analysis. The ceramics were pyrolyzed at1000℃ followed by further annealing in N2, and SiC nano-crystallites start to emerge at 1200℃ and dominate at 1500℃. Observed by high-angle annular dark-field imaging, bright and dark clusters were revealed as universal nano-structured features in ceramic matrices before and after nucleation, and the growth of cluster size saturated before reaching 5 nm at 1400℃. EELS analysis demonstrated the gradual development of bonding structures successively into SiC, graphetic BNCxand Si3N4 phases, as well as a constant presence of unexpected oxygen in the matrices. Furthermore, EELS profiling revealed the bright SiC clusters and less bright Si3N4-like clusters at 1200–1400℃. Since the amorphous matrix has already phase separated into SiCN and carbon clusters, another phase separation of SiCN into SiC and Si3N4-like clusters might occur by annealing to accompany their nucleation and growth, albeit one crystallized and another remained in amorphous structure. Hinderance of the cluster growth and further crystallization was owing to the formation of BNCxlayers that developed between SiC and Si3N4-like clusters as well as from the excessive oxygen to form the stable SiO2.