scholarly journals Constraints on models for the flagellar rotary motor

2000 ◽  
Vol 355 (1396) ◽  
pp. 491-501 ◽  
Author(s):  
Howard C. Berg
Keyword(s):  
Hydrogen Isotope ◽  
Room Temperature ◽  
Cytoplasmic Membrane ◽  
Sodium Ion ◽  
Protonmotive Force ◽  
Revolution Speed ◽  
High Speeds ◽  
Rotary Motor ◽  
Inside Out ◽  
Do So

Most bacteria that swim are propelled by flagellar filaments, each driven at its base by a rotary motor embedded in the cell wall and cytoplasmic membrane. A motor is about 45 nm in diameter and made up of about 20 different kinds of parts. It is assembled from the inside out. It is powered by a proton (or in some species, a sodium–ion) flux. It steps at least 400 times per revolution. At low speeds and high torques, about 1000 protons are required per revolution, speed is proportional to protonmotive force, and torque varies little with temperature or hydrogen isotope. At high speeds and low torques, torque increases with temperature and is sensitive to hydrogen isotope. At room temperature, torque varies remarkably little with speed from about –100 Hz (the present limit of measurement) to about 200 Hz, and then it declines rapidly, reaching zero at about 300 Hz. These are facts that motor models should explain. None of the existing models for the flagellar rotary motor completely do so.

scholarly journals MINIMAL VARIATION OF DEFECT STRUCTURE DUE TO THE ORDER OF ROOM TEMPERATURE HYDROGEN ISOTOPE IMPLANTATION AND SELF-ION IRRADIATION IN NICKEL

MRS Advances ◽  
2016 ◽  
Vol 1 (42) ◽  
pp. 2887-2892
Author(s):  
Brittany Muntifering ◽  
Jianmin Qu ◽  
Khalid Hattar
Keyword(s):  
Dislocation Loop ◽  
Hydrogen Isotope ◽  
Room Temperature ◽  
Ion Irradiation ◽  
In Situ Tem ◽  
Loop Formation ◽  
Radiation Induced ◽  
Formation And Evolution ◽  
And Performance ◽  
Induced Defects

ABSTRACTThe formation and stability of radiation-induced defects in structural materials in reactor environments significantly effects their integrity and performance. Hydrogen, which may be present in significant quantities in future reactors, may play an important role in defect evolution. To characterize the effect of hydrogen on cascade damage evolution, in-situ TEM self-ion irradiation and deuterium implantation was performed, both sequentially and concurrently, on nickel. This paper presents preliminary results characterizing dislocation loop formation and evolution during room temperature deuterium implantation and self-ion irradiation and the consequence of the sequence of irradiation. Hydrogen isotope implantation at room temperature appears to have little or no effect on the final dislocation loop structures that result from self-ion irradiation, regardless of the sequence of irradiation. Tilting experiments emphasize the importance of precise two-beam conditions for characterizing defect size and structure.

scholarly journals H/D Exchange Under Mild Conditions in Arenes and Unactivated Alkanes with C6D6 and D2O Using Rigid, Electron-rich Iridium PCP Pincer Complexes

2020 ◽  
Author(s):  
Joel D. Smith ◽  
George Durrant ◽  
Daniel Ess ◽  
Warren Piers
Keyword(s):  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Room Temperature ◽  
Pincer Complexes ◽  
Synthesis And Characterization ◽  
Hydrogen Isotope Exchange ◽  
Mild Conditions ◽  
Highly Active ◽  
Pcp Pincer

<div>The synthesis and characterization of an iridium polyhydride complex (Ir-H4)</div><div>supported by an electron-rich PCP framework is described. This complex readily loses molecular</div><div>hydrogen allowing for rapid room temperature hydrogen isotope exchange (HIE) at the hydridic</div><div>positions and the α-C-H site of the ligand with deuterated solvents such as benzene-d6, toluene-d8</div><div>and THF-d8. The removal of 1-2 equivalents of molecular H2 forms unsaturated iridium carbene</div><div>trihydride (Ir-H3) or monohydride (Ir-H) compounds that are able to create further unsaturation</div><div>by reversibly transferring a hydride to the ligand carbene carbon. These species are highly active</div><div>hydrogen isotope exchange (HIE) catalysts using C6D6 or D2O as deuterium sources for the</div><div>deuteration of a variety of substrates. By modifying conditions to influence the Ir-Hn speciation,</div><div>deuteration levels can range from near exhaustive to selective only for sterically accessible sites.</div><div>Preparative level deuterations of select substrates were performed allowing for procurement of</div><div>>95% deuterated compounds in excellent isolated yields; the catalyst can be regenerated by</div><div>treatment of residues with H2 and is still active for further reactions.</div>

N-doped ordered mesoporous carbon as a high performance anode material in sodium ion batteries at room temperature

RSC Advances ◽  
2014 ◽  
Vol 4 (107) ◽  
pp. 62673-62677 ◽  
Author(s):  
Zhiguang Wang ◽  
Yueming Li ◽  
Xiao-Jun Lv
Keyword(s):  
Electrochemical Performance ◽  
Anode Material ◽  
Mesoporous Carbon ◽  
High Performance ◽  
Room Temperature ◽  
Ordered Mesoporous Carbon ◽  
Sodium Ion ◽  
Template Method ◽  
Sodium Ion Batteries ◽  
Ordered Mesoporous

N-doped ordered mesoporous carbon preparedviaa template method showed improved electrochemical performance as an anode material in sodium ion batteries.

Acrasin, the Chemotactic Agent in Cellular Slime Moulds

1956 ◽  
Vol 33 (4) ◽  
pp. 645-657
Author(s):  
B. M. SHAFFER
Keyword(s):  
Room Temperature ◽  
Dialysis Membrane ◽  
Relay System ◽  
Highly Active ◽  
Slime Moulds ◽  
Cellular Slime ◽  
Set Up ◽  
Cellular Slime Moulds ◽  
Extracellular Slime ◽  
Do So

1. A study has been made of acrasin, the agent inducing chemotaxis in the amoebae of cellular slime moulds. 2. A method has been developed for subjecting sensitive amoebae to a fluctuating gradient set up by an artificial source that can be renewed at intervals of as little as a few seconds with fresh test solution. 3. Amoebae orient to a gradient maintained with the cell-free liquid freshly obtained from the immediate surroundings of a natural source. 4. Acrasin solution as secreted loses its activity very rapidly at room temperature. 5. A highly active stable solid is obtained by drying methanolic culture extracts; it resists boiling and exposure to acids and alkalis. Its solubility decreases rapidly in passing up the alcohol series. 6. The original instability has been shown to be due to the presence of another extracellular slime-mould product, possibly an enzyme; it, unlike acrasin, cannot pass rapidly across a dialysis membrane, is heat labile, and can be precipitated by ammonium sulphate. 7. The advantages of the organism's itself inactivating acrasin are considered. 8. Some of the advantages of a source's releasing acrasin in pulses are discussed; but it is not essential for orientation for it to do so. 9. Sensitive amoebae not only are oriented by an acrasin solution but are caused to secrete acrasin: this is the basis of a chemotactic relay system.

Room-Temperature Fabrication of a Liquid NaK Alloy-Based Membrane Electrode for Sodium-Ion Batteries

2020 ◽  
Vol 12 (18) ◽  
pp. 20423-20428
Author(s):  
Junfeng Yang ◽  
Xusheng Wang ◽  
Shizhi Huang ◽  
Xinxiang Zhang ◽  
Jitao Chen
Keyword(s):  
Room Temperature ◽  
Sodium Ion ◽  
Membrane Electrode ◽  
Sodium Ion Batteries

High-quality Prussian blue crystals as superior cathode materials for room-temperature sodium-ion batteries

2014 ◽  
Vol 7 (5) ◽  
pp. 1643-1647 ◽  
Author(s):  
Ya You ◽  
Xing-Long Wu ◽  
Ya-Xia Yin ◽  
Yu-Guo Guo
Keyword(s):  
Prussian Blue ◽  
Water Content ◽  
Cathode Materials ◽  
Room Temperature ◽  
Specific Capacity ◽  
Sodium Ion ◽  
Sodium Ion Batteries ◽  
Cycle Stability ◽  
High Quality ◽  
High Specific Capacity

High-quality Prussian blue crystals with a small number of vacancies and a low water content show high specific capacity and remarkable cycle stability as cathode materials for Na-ion batteries.

Electrocatalytic reduction of nitrate and selenate by NapAB

2011 ◽  
Vol 39 (1) ◽  
pp. 236-242 ◽  
Author(s):  
Andrew J. Gates ◽  
Clive S. Butler ◽  
David J. Richardson ◽  
Julea N. Butt
Keyword(s):  
Cytoplasmic Membrane ◽  
Current Knowledge ◽  
Reductase Activity ◽  
Protonmotive Force ◽  
Metabolic Diversity ◽  
Protein Film ◽  
Carbon Substrates ◽  
Redox Poise ◽  
Paracoccus Pantotrophus ◽  
High Level

Bacterial cellular metabolism is renowned for its metabolic diversity and adaptability. However, certain environments present particular challenges. Aerobic metabolism of highly reduced carbon substrates by soil bacteria such as Paracoccus pantotrophus presents one such challenge since it may result in excessive electron delivery to the respiratory redox chain when compared with the availability of terminal oxidant, O2. The level of a periplasmic ubiquinol-dependent nitrate reductase, NAP, is up-regulated in the presence of highly reduced carbon substrates. NAP oxidizes ubiquinol at the periplasmic face of the cytoplasmic membrane and reduces nitrate in the periplasm. Thus its activity counteracts the accumulation of excess reducing equivalents in ubiquinol, thereby maintaining the redox poise of the ubiquinone/ubiquinol pool without contributing to the protonmotive force across the cytoplasmic membrane. Although P. pantotrophus NapAB shows a high level of substrate specificity towards nitrate, the enzyme has also been reported to reduce selenate in spectrophotometric solution assays. This transaction draws on our current knowledge concerning the bacterial respiratory nitrate reductases and extends the application of PFE (protein film electrochemistry) to resolve and quantify the selenate reductase activity of NapAB.

Design and Comparative Study of O3/P2 Hybrid Structures for Room Temperature Sodium-Ion Batteries

2017 ◽  
Vol 9 (46) ◽  
pp. 40215-40223 ◽  
Author(s):  
Xingguo Qi ◽  
Lilu Liu ◽  
Ningning Song ◽  
Fei Gao ◽  
Kai Yang ◽  
...  
Keyword(s):  
Comparative Study ◽  
Room Temperature ◽  
Sodium Ion ◽  
Hybrid Structures ◽  
Sodium Ion Batteries

Electrolyte design strategies and research progress for room-temperature sodium-ion batteries

2017 ◽  
Vol 10 (5) ◽  
pp. 1075-1101 ◽  
Author(s):  
Haiying Che ◽  
Suli Chen ◽  
Yingying Xie ◽  
Hong Wang ◽  
Khalil Amine ◽  
...  
Keyword(s):  
Room Temperature ◽  
Low Cost ◽  
Sodium Ion ◽  
Research Progress ◽  
Sodium Ion Batteries ◽  
Design Strategies ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Functional Development ◽  
Electrochemical Window

Electrolyte design or functional development is very effective at promoting the performance of sodium-ion batteries, which are attractive for electrochemical energy storage devices due to abundant sodium resources and low cost. The roadmap of the sodium ion batteries based on electrolyte materials was drawn firstly and shows that the electrolyte type decides the electrochemical window and energy density.

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