scholarly journals Slow Kinetics of Brownian Maxima

2014 ◽  
Vol 113 (3) ◽  
Author(s):  
E. Ben-Naim ◽  
P. L. Krapivsky
Keyword(s):  
Slow Kinetics ◽  
Kinetics Of

scholarly journals Unusually sluggish microemulsion system with water, toluene and a technical branched alkyl polyethoxylate

2015 ◽  
Vol 21 (3) ◽  
pp. 429-439 ◽  
Author(s):  
Marija Ilic ◽  
Franz-Hubert Haegel ◽  
Vesna Pavelkic ◽  
Snezana Zlatanovic ◽  
Zoran Markovic ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Nonionic Surfactants ◽  
Binary Phase Diagram ◽  
Visual Observation ◽  
Ternary Mixtures ◽  
Microemulsion System ◽  
Slow Kinetics ◽  
Bicontinuous Microemulsion ◽  
Kinetics Of ◽  
Qualitative Measurements

Microemulsion systems with water, toluene and nonionic surfactants are interesting for application due to the excellent solvent properties of aromatic hydrocarbons. In this study, the pseudo-binary phase diagram (?fish-diagram?) of such a ternary system was investigated using a branched technical alkyl polyethoxylate. Lutensol ON 50 (i-C10E5) was considered a suitable surfactant. The system with technical branched i-C10E5 exhibits very long and for compositions near optimum solubilization, i.e. the minimum content of surfactant needed for a bicontinuous microemulsion, extremely long times for equilibration. In addition to visual observation, qualitative measurements of turbidity were performed with a UV-Vis spectrometer for characterizing the behavior of this unusually sluggish system. Isothermal phase diagrams at 20, 25 and 30?C yielded inconsistent results after the change of temperature and the application of mechanical stress for different treatment of the samples. Ternary mixtures of water, toluene, and Lutensol ON 50 seem to form long-living metastable states. The sluggishness and the ambiguous phase behavior of the system are discussed. Inconsistent results are attributed to the slow kinetics of the formation and destruction of liquid crystals and the ability of the system to form miniemulsions within an unusual concentration range.

Slow kinetics of a potassium channel inAcetabularia

1988 ◽  
Vol 102 (2) ◽  
pp. 141-152 ◽  
Author(s):  
A. Bertl ◽  
H. G. Klieber ◽  
D. Gradmann
Keyword(s):  
Potassium Channel ◽  
Slow Kinetics ◽  
Kinetics Of

Nitrogen doped porous carbon fiber/vertical graphene as efficient polysulfide conversion catalyst for high performance lithium sulfur batteries

2021 ◽  
Author(s):  
junsheng lin ◽  
Yangcheng Mo ◽  
Shiwen Li ◽  
Jie Yu
Keyword(s):  
High Performance ◽  
Practical Application ◽  
Nitrogen Doped ◽  
High Sulfur Content ◽  
Slow Kinetics ◽  
Lithium Sulfur Batteries ◽  
Conversion Catalyst ◽  
Kinetics Of ◽  
Lithium Sulfur ◽  
High Sulfur Loading

Under high sulfur loading, high sulfur content and low electrolyte/sulfur ratio (E/S), the practical application of lithium sulfur (Li–S) batteries is seriously limited by the negative and slow kinetics of...

scholarly journals Recent Advances in Nanostructured Transition Metal Carbide- and Nitride-Based Cathode Electrocatalysts for Li–O2 Batteries (LOBs): A Brief Review

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2106
Author(s):  
K. Karuppasamy ◽  
K. Prasanna ◽  
Vasanth Rajendiran Jothi ◽  
Dhanasekaran Vikraman ◽  
Sajjad Hussain ◽  
...  
Keyword(s):  
Transition Metal ◽  
Rational Design ◽  
Rate Capability ◽  
High Energy ◽  
High Energy Density ◽  
Electrochemical Kinetics ◽  
Transition Metal Carbide ◽  
Round Trip ◽  
Slow Kinetics ◽  
Kinetics Of

A large volume of research on lithium–oxygen (Li–O2) batteries (LOBs) has been conducted in the recent decades, inspired by their high energy density and power density. However, these future generation energy-storage devices are still subject to technical limitations, including a squat round-trip efficiency and a deprived rate-capability, due to the slow-moving electrochemical kinetics of both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) over the surface of the cathode catalyst. Because the electrochemistry of LOBs is rather complex, only a limited range of cathode catalysts has been employed in the past. To understand the catalytic mechanisms involved and improve overall cell performance, the development of new cathode electrocatalysts with enhanced round-trip efficiency is extremely important. In this context, transition metal carbides and nitrides (TMCs and TMNs, respectively) have been explored as potential catalysts to overcome the slow kinetics of electrochemical reactions. To provide an accessible and up-to-date summary for the research community, the present paper reviews the recent advancements of TMCs and TMNs and its applications as active electrocatalysts for LOBs. In particular, significant studies on the rational design of catalysts and the properties of TMC/TMN in LOBs are discussed, and the prospects and challenges facing the continued development of TMC/TMN electrocatalysts and strategies for attaining higher OER/ORR activity in LOBs are presented.

scholarly journals Slow kinetics of inositol 1,4,5-trisphosphate-induced Ca2+ release: is the release ‘quantal’ or ‘non-quantal’?

1997 ◽  
Vol 323 (1) ◽  
pp. 123-130 ◽  
Author(s):  
Ludwig MISSIAEN ◽  
Humbert DE SMEDT ◽  
Jan B. PARYS ◽  
Ilse SIENAERT ◽  
Henk SIPMA ◽  
...  
Keyword(s):  
Low Dose ◽  
Slow Phase ◽  
Quantal Response ◽  
Published Evidence ◽  
A7r5 Cells ◽  
Slow Kinetics ◽  
Inositol 1,4,5 Trisphosphate ◽  
Long Time ◽  
High Concentrations ◽  
Kinetics Of

Inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ release from intracellular stores is generally assumed to be a ‘quantal’ process because low InsP3 concentrations mobilize less Ca2+ than high concentrations and a submaximal concentration does not release all the InsP3-mobilizable Ca2+. However, some recent reports questioned the generally accepted view that a low dose of InsP3 is unable to empty the whole store. We have now challenged the stores of permeabilized A7r5 cells in InsP3 for much longer periods than previously reported, to assess directly whether the slow phase of the release would empty the whole store (a non-quantal response) or only a fraction of it (a quantal response). Addition of a maximal [InsP3] at the end of a prolonged (92 min) stimulation with a submaximal [InsP3] resulted in additional Ca2+ release. Experiments in which the stores were challenged with different submaximal InsP3 concentrations for long time periods revealed that a lower [InsP3] never released the same amount of Ca2+ as a higher [InsP3]. This quantal pattern of Ca2+ release occurred both at 25 °C and at 4 °C. There was a time-dependent increase in the fraction of Ca2+ recruited by the lower compared with the higher [InsP3]. This recruitment of Ca2+ persisted if the [InsP3] was decreased, but was largely prevented by palmitoyl-CoA, a potent blocker of the luminal Ca2+ translocation between individual store units. ATP, in the presence of InsP3, released Ca2+ under conditions permitting the recruitment of no additional InsP3 receptors, indicating that an all-or-none emptying of a fraction of the stores cannot be the only mechanism responsible for quantal Ca2+ release in A7r5 cells. We conclude that some of the previously published evidence for a non-quantal Ca2+ release pattern should be reinterpreted.

scholarly journals Innovative catalyst design for the oxygen reduction reaction for fuel cells

2016 ◽  
Vol 7 (5) ◽  
pp. 3364-3369 ◽  
Author(s):  
Kenichi Shimizu ◽  
Lior Sepunaru ◽  
Richard G. Compton
Keyword(s):  
Hydrogen Peroxide ◽  
Fuel Cell ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Catalyst System ◽  
Reduction Reaction ◽  
Catalyst Design ◽  
Fuel Cell Catalyst ◽  
Slow Kinetics ◽  
Kinetics Of

A bifunctional fuel cell catalyst system demonstrated herein overcomes the slow kinetics of the oxygen reduction reaction by rapid heterogeneous disproportionation of hydrogen peroxide.

Microbial Ferrous Ion Oxidation versus Ferric Ion Precipitation at Low Temperature Conditions

2017 ◽  
Vol 262 ◽  
pp. 381-384 ◽  
Author(s):  
Emmanuel Chinonso Chukwuchendo ◽  
Tunde Victor Ojumu
Keyword(s):  
Packed Column ◽  
Ferrous Ion ◽  
Design Management ◽  
Ferric Ion ◽  
Oxidation Rates ◽  
Temperature Conditions ◽  
First Order Kinetics ◽  
Slow Kinetics ◽  
Cold Condition ◽  
Kinetics Of

Ferric ion precipitation in a typical bioleach operation is known to be inevitable. However, its management has been emphasized as critical to efficiently maximize the potential that bioleach technique offers, especially in heap bioleach systems. Although there are some studies on ferric ion precipitation, limited studies exist in the context of a cold condition which often prevails in some operations. This study investigated ferrous ion biooxidation and ferric ion precipitation under cold temperature conditions. The results showed that maximum ferrous ion oxidation rates of 1.05, 1.25, 1.51 and 1.60 mmol/L/h at 6, 7, 8 and 10°C respectively were achieved in packed column reactor. The results further showed a simultaneous ferric ion precipitation during the oxidation process. The kinetics of ferric ion precipitation follows a first order kinetics with the rate constants of 0.0066, 0.0074, 0.0080 and 0.011 h-1. Activation energies of 68 and 77 kJ/mol were obtained for both ferrous ion biooxidation and ferric ion precipitation respectively. Although slow kinetics are expected for both processes, the kinetics information may be useful for design management consideration at least to predict when bioleach liquor would likely run out of dissolved ferric ion.

Hydrogenation and Dehydrogenation Properties of Mg-Cu, Mg-Al Eutectic Alloy

2009 ◽  
Vol 1216 ◽  
Author(s):  
Ho Shin ◽  
Yuma Eto ◽  
Hiroyuki T. Takeshita ◽  
Koji Tanaka
Keyword(s):  
Eutectic Alloy ◽  
Functional Materials ◽  
Rolling Process ◽  
Sintering Process ◽  
Practical Application ◽  
Hydrogen Density ◽  
Storage Study ◽  
Major Subject ◽  
Slow Kinetics ◽  
Kinetics Of

AbstractMg has 7.6 mass% of high gravimetric hydrogen density, an abundance of resources and inexpensive price compared with other functional materials. Owing to these merits, it has been the major subject of hydrogen storage study. However, it is unsuitable for practical application due to thermodynamic stability and slow kinetics of Mg hydride. Therefore, many ways such as fabrication of nanocrystalline or addition of catalyst have been proposed to solve the problems of Mg hydride system. Copper and aluminum are inexpensive and can obtain easily as well as Mg. Each eutectic alloy could be produced by sintering process and observed improvement of reaction with hydrogen. Mg2Cu laminate, one phase of Mg-Cu eutectic alloy, could also be produced by cold-rolling process, and it showed reversible reaction with hydrogen, at this study.

Evidence of Radiolytic Oxidation of 241Am in Na+ / Cl− / HCO−3/ CO2−3 Media.

1992 ◽  
Vol 294 ◽  
Author(s):  
Eric Giffaut ◽  
Pierre Vitorge
Keyword(s):  
Aqueous Phase ◽  
Waste Disposal ◽  
Metallic Iron ◽  
Room Temperature ◽  
Extraction Methods ◽  
Slow Kinetics ◽  
Solid Phases ◽  
Radiolytic Oxidation ◽  
Chemical Conditions ◽  
Kinetics Of

ABSTRACTThis paper examines Americium behaviour in CI− media at room temperature in connection with environmental and waste disposal programs. Most published values on U, Np, Pu and Am complexation in chloride media have been determined using extraction methods. Spectrophotometric techniques are not sensitive enough to prove actinide complexation by chloride, which is confirmed in this paper for Am(III).Am(OH)3(s), AmOHCO3(s), Am2(CO3)3(s) or NaAm(CO3)2(s) solid phases can control the Am solubility, depending on the chemical conditions of the aqueous phase (usually PCO2). 241Am solubility is here found to be higher in NaCl 4M media than in NaCl 0.1 M (up to 3 orders of magnitude). Addition of a reducing agent (metallic iron) lowers the solubility. After a week, solubilities in NaCl 0.1 M and 4 M are similar. These results are consistent with Am(III) radiolytic oxidation to Am(V), due to cc radiations. Little evidence of Cl− or mixed Cl−-CO2−3 complexes is found in these conditions. In Na+-OH−-Cl− media, 241Am(III) oxidation had also been proposed. Slow kinetics of precipitation could induce experimental uncertainities.

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