Scalable Water‐Based Production of Highly Conductive 2D Nanosheets with Ultrahigh Volumetric Capacitance and Rate Capability

Highly conductive and ultrathin 2D nanosheets are of importance for the development of portable electronics and electric vehicles. However, scalable production and rational design for highly electronic and ionic conductive 2D nanosheets still remain a challenge. Herein, an industrially adoptable fluid dynamic exfoliation process is reported to produce large quantities of ionic liquid (IL)‐functionalized metallic phase MoS₂ (m‐MoS₂) and defect‐free graphene (Gr) sheets. Hybrid 2D–2D layered films are also fabricated by incorporating Gr sheets into compact m‐MoS₂ films. The incorporated IL functionalities and Gr sheets prevent aggregation and restacking of the m‐MoS₂ sheets, thereby creating efficient and rapid ion and electron pathways in the hybrid films. The hybrid film with a high packing density of 2.02 g cm^?3 has an outstanding volumetric capacitance of 1430.5 F cm^?3 at 1 A g^?1 and an extremely high rate capability of 80% retention at 1000 A g^?1. The flexible supercapacitor assembled using a polymer‐gel electrolyte exhibits excellent resilience to harsh electrochemical and mechanical conditions while maintaining an impressive rate performance and long cycle life. Successful achievement of an ultrahigh volumetric energy density (1.14 W h cm^?3) using an organic electrolyte with a wide cell voltage of ≈3.5 V is demonstrated.     

The Synergistic Effect of Cation and Anion of an Ionic Liquid Additive for Lithium Metal Anodes

Lithium metal anodes are steadily gaining more attention, as their superior specific capacities and low redox voltage can significantly increase the energy density of rechargeable batteries far beyond those of current Li‐ion batteries. Nonetheless, the relevant technology is still in a premature research stage mainly due to the uncontrolled growth of Li dendrites that ceaselessly cause unwanted side reactions with electrolyte. In order to circumvent this shortcoming, herein, an ionic liquid additive, namely, 1‐dodecyl‐1‐methylpyrrolidinium (Pyr1(12)⁺) bis(fluorosulfonyl)imide (FSI^?), for conventional electrolyte solutions is reported. The Pyr1(12)⁺ cation with a long aliphatic chain mitigates dendrite growth via the combined effects of electrostatic shielding and lithiophobicity, whereas the FSI^? anion can induce the formation of rigid solid–electrolyte interphase layers. The synergy between the cation and anion significantly improves cycling performance in asymmetric and symmetric control cells and a full cell paired with an LiFePO₄ cathode. The present study provides a useful insight into the molecular engineering of electrolyte components by manipulating the charge and structures of the involved molecules.     

Bare laser‐synthesized Au‐based nanoparticles as nondisturbing surface‐enhanced Raman scattering probes for bacteria identification

The ability of noble metal‐based nanoparticles (NPs) (Au, Ag) to drastically enhance Raman scattering from molecules placed near metal surface, termed as surface‐enhanced Raman scattering (SERS), is widely used for identification of trace amounts of biological materials in biomedical, food safety and security applications. However, conventional NPs synthesized by colloidal chemistry are typically contaminated by nonbiocompatible by‐products (surfactants, anions), which can have negative impacts on many live objects under examination (cells, bacteria) and thus decrease the precision of bioidentification. In this article, we explore novel ultrapure laser‐synthesized Au‐based nanomaterials, including Au NPs and AuSi hybrid nanostructures, as mobile SERS probes in tasks of bacteria detection. We show that these Au‐based nanomaterials can efficiently enhance Raman signals from model R6G molecules, while the enhancement factor depends on the content of Au in NP composition. Profiting from the observed enhancement and purity of laser‐synthesized nanomaterials, we demonstrate successful identification of 2 types of bacteria (Listeria innocua and Escherichia coli). The obtained results promise less disturbing studies of biological systems based on good biocompatibility of contamination‐free laser‐synthesized nanomaterials.

     

Pectin immunolocalization and calcium visualization in differentiating derivatives from poplar cambium

Summary Calcium distribution and pectin esterification patterns in the cambial zone of poplar branches were studied with ionic microscopy and immunological tools respectively. Dynamic changes correlating with cell growth and cell differentiation were observed both on the xylem and on the phloem sides. In expanding cell walls of xylem derivatives, unesterified pectins were restricted to cell junctions and middle lamellae, occasionally accompanied by calcium ions. In contrast, in differentiating and mature phloem cells, acidic pectins and Ca²⁺ were present all over the walls leading to early stiffening of the polysaccharide network. Significant labelling was detected with JIM5 antibodies in some dictyosomes suggesting exocytosis of low methylated polymers towards the cell walls. At cell junctions, unesterified pectins might originate from the activity of pectinmethylesterases localized in these areas. Thus un- and deesterified pectins might be located in different cell wall domains whose distribution, varying with cell type, will confer specific extensibility to the wall matrix.Abbreviations BSA bovine serum albumin - DM degree of methylation - FITC fluorescein isothiocyanate - HM highly methylated pectins - LM low methylated pectins - PME pectin methylesterase - SIMS secondary ion mass spectrometry - TBS tris-buffered saline     

Funktionsmorphologie des Exkretionsorgans des Spulwurms Ascaris lumbricoides L.

Zusammenfassung Das Seitenkanalsystem von Ascaris lumbricoides wurde elektronenmikroskopisch untersucht. Beim erwachsenen Tier erstreckt sich das in den lateralen Epidermisleisten eingebettete einzellige Organ vom Nervenring bis etwa zur Körpermitte. Im 2. Körperviertel besitzt es kein durchgehendes Kanallumen und erscheint degeneriert. In allen übrigen Bereichen (mit Ausnahme des Ausführungskanals) besitzt es den gleichen Aufbau aus zwei Schichten. Die das Kanallumen begrenzende innere Schicht enthält zahlreiche extraplasmatische Räume, von denen zumindest die am weitesten innen liegenden mit dem Kanallumen kommunizieren. Die äußere Zellmembran besitzt viele Einfaltungen, von denen einige weit in das Cytoplasma hineinragen. Der Gewebeanteil der lateralen Epidermisleisten, der dem Seitenkanalsystem unmittelbar anliegt, enthält sehr viele Interzellularräume, die ein zusammenhängendes Drainage-System bilden. Zur histochemischen Lokalisation von ATP-ase-Aktivität wurden Experimente durchgeführt. Die möglichen Mechanismen der Bildung der Exkretflüssigkeit werden diskutiert unter Berücksichtigung bereits veröffentlichter physiologischer Befunde.

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Ultrastructure and function of the excretory organ of Ascaris lumbricoides L. (Nematoda)

Summary The Excretory organ (H-system) of Ascaris lumbricoides has been investigated electronmicroscopically. In adult animals this single-cell-organ embedded in the lateral lines extends from the nerve ring to approximately the middle of the body.In the second quarter of the body it lacks a continuous canal lumen, and it seems to be degenerated. In all of the other regions (except the stem leading to the excretory pore) it consists of two zones. The inner zone lining the canal lumen contains several extraplasmatic spaces; at least those placed the farthest inside communicate with the canal lumen. The outer cell membrane shows many infoldings, some of which extend deeply into the cytoplasm. The tissue of the lateral line adjacent to the canal system contains very many intercellular spaces which build a coherent intracellular rainage-system. Experiments have been performed in order to localize the ATPase activity histochemically. Possible mechanisms for the forming of the excretory fluid are discussed under consideration of physiological results already published.

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Abkürzungen Ak Ausführungskanal - Bm Basalmembran - Cp Cytoplasmaplatten - lE linke Epidermisleiste - rE rechte Epidermisleiste - Ef Einfaltungen der äußeren Zellmembran - Fb Fibrillenbündel - Go Go Golgiapparat - Hg Hüllgewebe - Is lamelläre Interzellularsubstanz - Iz Interzellularraum - Kl Kanallumen - K Kutikula - Lh Leibeshöhle - Mu Muskelzelle - Mi Mitochondrien - Ms mittlerer Gewebestreifen (= Mittelstreifen) der Epidermisleiste - Mt Mikrotubuli - N Zellkern - No Nucleolus - Ne Nervenring - eP elektronendichte Partikel - sP sphärische Partikel - P Kernpore - Q Querbalken - epR extraplasmatischer Raum - Lho Längsholm - Mf Membranfusion - äS äußere Schicht des Seitenkanalsystems - iS innere Schicht der Längsholme - Sy syncytiale Cytoplasmamasse ohne Interzellularen - V Verzweigungskanal - iZ innere Zone um einen Verzweigungskanal Inauguraldissertation der Mathematisch-Naturwissenschaftlichen Fakultät der Freien Universität Berlin (gekürzt). Herrn Prof. Dr. G. Kümmel danke ich für die Anregung zu diesem Thema und für sein ständiges kritisches Interesse der Untersuchung, Frau C. S. Friedemann für die Anfertigung der Zeichnungen und Fräulein H. Schmidt für technische Assistenz.     

The Influence of Environmental Factors on the Respiration of Plant-Parasitic Nematodes

Respiration of selected nematode species was measured relative to CO₂ level, temperature, osmotic pressure, humidity, glucose utilization and high ionic concentrations of sodium and potassium.In general, respiration was stimulated most by the dominant environmental factors at levels near those expected in the nematode''s "natural" habitat. Soil-inhabiting nematodes utilized O₂, most rapidly with high (1-2%) CO₂ whereas a foliar nematode (Aphelenchoides ritzemabosi) did so with 0.03% CO₂, the concentration typically found in air. Temperature optima for respiration corresponded closely to those for other activities. Ditylenchus dipsaci and Pratylenchus penetrans adults and Anguina tritici and A. agrostis second-stage larvae respired within the range of osmotic pressures from 0 to 44.8 arm and respiration of their drought-resistant stages was stimulated by increasing osmotic pressure which accompanies the onset of drought. Rehydration of A. tritici and A. agrostis larvae with RH as low as 5% stimulated measurable respiration. Glucose utilization from liquid medium by A. tritici larvae or A. ritzembosi was not detectable. Supplemental Na⁺ stimulated respiration of Anguina tritici, K⁺ did not.     

Effects of protein-protein interactions on electron transfer: docking and electron transfer calculations for complexes between flavodoxin and c-type cytochromes

 Theoretical studies of protein-protein association and electron transfer were performed on the binary systems formed by Desulfovibrio vulgaris Hildenborough (D. v. H.) flavodoxin and D. v. H. cytochrome c ₅₅₃ and by flavodoxin and horse heart cytochrome c. Initial structures for the complexes were obtained by rigid-body docking and were refined by MD to allow for molecular flexibility. The structures thus obtained were analysed in terms of their relative stability through the calculation of excess energies. Electrostatic, van der Waals and solvation energy terms showed all to have significant contributions to the stability of complexes. In the best association solutions found for both cytochromes, these bind to different zones of flavodoxin. The binding site of flavodoxin observed for cytochrome c is in accordance with earlier works [27]. The various association modes found were characterised in terms of electron transfer using the Pathways model. For complexes between flavodoxin and horse heart cytochrome c, some correlation was observed between electron tunnelling coupling factors and conformation energy; the best conformation found for electron transfer corresponded also to the best one in terms of energy. For complexes between flavodoxin and cytochrome c ₅₅₃ this was not the case and a lower correlation was observed between electron tunnelling coupling factors and excess energies. These results are in accordance with the differences in the experimental dependence of electron transfer rates with ionic strength observed between these two cases. Received: 29 December 1998 / Accepted: 22 March 1999     

Leishmania amazonensis Infection Induces Changes in the Electrophysiological Properties of Macrophage-like Cells

Whole cell patch-clamp recordings were used to study the electrical properties of the macrophage-like cell line J774.1, after infection with Leishmania amazonensis. Infection induced a significant increase in cell size and membrane capacitance, suggesting that parasite invasion leads to the addition of plasma membrane to the host cell. By 24 hr after infection, the host cell membrane potential was significantly more hyperpolarized than control cells, and this difference remained for the subsequent 72 hr post-infection. The hyperpolarization was paralleled by an increase in the density of inward rectifying K⁺ currents. The shape of the conductance vs. voltage curve, the kinetic properties and the pharmacological profile of these currents were not significantly altered by infection. These results suggest that infection by L. amazonensis causes an increase in the number of functional inward rectifying K⁺ channels, leading to hyperpolarization of the host cell membrane. Received: 19 January 1999/Revised: 20 April 1999     

Electrochemical Energy Storage with a Reversible Nonaqueous Room‐Temperature Aluminum–Sulfur Chemistry

A reversible room‐temperature aluminum–sulfur (Al‐S) battery is demonstrated with a strategically designed cathode structure and an ionic liquid electrolyte. Discharge–charge mechanism of the Al‐S battery is proposed based on a sequence of electrochemical, microscopic, and spectroscopic analyses. The electrochemical process of the Al‐S battery involves the formation of a series of polysulfides and sulfide. The high‐order polysulfides (S_x^2?, x ≥ 6) are soluble in the ionic liquid electrolyte. Electrochemical transitions between S₆^2? and the insoluble low‐order polysulfides or sulfide (S_x ^2?, 1 ≤ x < 6) are reversible. A single‐wall carbon nanotube coating applied to the battery separator helps alleviate the diffusion of the polysulfide species and reduces the polarization behavior of the Al‐S batteries.