La3+-Catalyzed Methanolysis of Phosphate Diesters. Remarkable Rate Acceleration of the Methanolysis of Diphenyl Phosphate, Methylp-Nitrophenyl Phosphate, and Bis(p-nitrophenyl) Phosphate

2001 ◽  
Vol 40 (14) ◽  
pp. 3588-3595 ◽  
Author(s):  
Alexei A. Neverov ◽  
R. S. Brown
Keyword(s):  
Nitrophenyl Phosphate ◽  
Rate Acceleration ◽  
Diphenyl Phosphate ◽  
Phosphate Diesters

Acceleration of the methanolysis of phosphate diesters promoted by La(OTf)3 — The analysis of non-integer pH/rate profiles resulting from changes in metal ion speciation

2005 ◽  
Vol 83 (9) ◽  
pp. 1268-1276 ◽  
Author(s):  
Graham TT Gibson ◽  
Alexei A Neverov ◽  
Allen Chun-Tien Teng ◽  
R S Brown
Keyword(s):  
Kinetic Data ◽  
Metal Ion ◽  
General Observation ◽  
Transient Complex ◽  
Phosphate Diester ◽  
Nitrophenyl Phosphate ◽  
Speciation Diagrams ◽  
Diphenyl Phosphate ◽  
The Individual ◽  
Phosphate Diesters

In a previous publication (A.A. Neverov and R.S. Brown. Inorg. Chem. 40, 3588 (2001)) we reported very effective catalysis of the methanolysis of some phosphate diesters (methyl p-nitrophenyl phosphate (1), bis(p-nitrophenyl) phosphate (2), and diphenyl phosphate (3)) promoted by La3+, and noted a general observation that the plots of logkcat vs. [Formula: see text]pH had non-integer gradients. In this report the origins of that behaviour are studied and analyzed through determination of the speciation of La3+(–OCH3)n, (La3+)2(–OCH3)m, (La3+)2:phosphate:(–OCH3)y forms in solution as a function of [Formula: see text]pH. Potentiometric titrations of solutions of La(OTf)3 in methanol at low (<1 × 10–4 mol/L) and high (>1 × 10–3 mol/L) concentration were analyzed through fits of the data to various models to provide speciation diagrams of the various La3+ forms in the absence of phosphate. Titrations of La3+ in the presence of diphenyl phosphate were also analyzed to provide speciation diagrams for phosphate bound forms. The kinetic data for the La3+ catalyzed methanolysis of 1 were analyzed through fitting the kinetic data at low and high [La3+] as a function of [Formula: see text]pH to a linear combination of the individual kinetic contributions of each species. Overall the data are best analyzed in the low [La3+] domain as resulting from methoxide attack on a transient complex of phosphate bound to La3+(–OCH3)0,1. In the high [La3+] domain the data fit two kinetically equivalent processes involving either a spontaneous decomposition of (La3+)2:1–:(–OCH3)2,3,4,5 or external methoxide attack on (La3+)2:1–:(–OCH3)1,2,3,4. Key words: lanthanides, phosphate diester, methanolysis, kinetics, speciation, metal ion catalysis of methanolysis, DNA model methanolysis.

THE HYDROLYSIS OF PHOSPHATE DIESTERS WITH BARIUM HYDROXIDE

1955 ◽  
Vol 33 (4) ◽  
pp. 705-710 ◽  
Author(s):  
C. W. Helleiner ◽  
G. C. Butler
Keyword(s):  
Sodium Hydroxide ◽  
Alkaline Hydrolysis ◽  
Small Proportion ◽  
Inorganic Phosphate ◽  
Barium Hydroxide ◽  
Phosphate Ester ◽  
Purine Nucleotides ◽  
Diphenyl Phosphate ◽  
Phosphate Diesters ◽  
Hydrolysis Of

The rate of alkaline hydrolysis of diphenyl phosphate has been found to be increased by the presence of barium. Similarly, desoxyribonucleate (DNA), which is not hydrolyzed rapidly by hot sodium hydroxide, is hydrolyzed by barium hydroxide. Only a very small proportion of the total phosphorus of either diphenyl phosphate or DNA is converted to inorganic phosphate during this hydrolysis. In addition to hydrolysis of the phosphate ester bonds of DNA, hot alkali also causes the deamination of desoxycytidylic acid residues and probably of the amino-purine nucleotides as well.

The Effect of Searching Versus Surfing on Cognitive and Emotional Responses to Online News

2009 ◽  
Vol 21 (2) ◽  
pp. 49-59 ◽  
Author(s):  
Kevin Wise ◽  
Hyo Jung Kim ◽  
Jeesum Kim
Keyword(s):  
Heart Rate ◽  
Skin Conductance ◽  
Skin Conductance Level ◽  
Emotional Responses ◽  
Online News ◽  
Self Report ◽  
Mixed Design ◽  
Information Need ◽  
News Stories ◽  
Rate Acceleration

A mixed-design experiment was conducted to explore differences between searching and surfing on cognitive and emotional responses to online news. Ninety-two participants read three unpleasant news stories from a website. Half of the participants acquired their stories by searching, meaning they had a previous information need in mind. The other half of the participants acquired their stories by surfing, with no previous information need in mind. Heart rate, skin conductance, and corrugator activation were collected as measures of resource allocation, motivational activation, and unpleasantness, respectively, while participants read each story. Self-report valence and recognition accuracy were also measured. Stories acquired by searching elicited greater heart rate acceleration, skin conductance level, and corrugator activation during reading. These stories were rated as more unpleasant, and their details were recognized more accurately than similar stories that were acquired by surfing. Implications of these results for understanding how people process online media are discussed.

Optimization of Perfusion Rate Acceleration is a Key Stage in Development of Highly Productive Perfusion Cultivation of CHO Cells

2016 ◽  
Vol 32 (4) ◽  
pp. 60-67
Author(s):  
A. N. MOROZOV ◽  
Z. V. ZAKHAROV ◽  
R. A. KOCHELABOV ◽  
D. V. TYUPA ◽  
A. V. ISERKAPOV ◽  
...  
Keyword(s):  
Cho Cells ◽  
Perfusion Rate ◽  
Rate Acceleration ◽  
Perfusion Cultivation

scholarly journals Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

2019 ◽  
Vol 15 ◽  
pp. 963-970 ◽  
Author(s):  
Sora Park ◽  
Jeung Gon Kim
Keyword(s):  
Ball Milling ◽  
Mechanochemical Synthesis ◽  
Polymeric Materials ◽  
Solvent Free ◽  
Energy Output ◽  
Polymerization Temperature ◽  
Mechanical Degradation ◽  
Trimethylene Carbonate ◽  
Rate Acceleration ◽  
Conventional Solution

Mechanochemical polymerization is a rapidly growing area and a number of polymeric materials can now be obtained through green mechanochemical synthesis. In addition to the general merits of mechanochemistry, such as being solvent-free and resulting in high conversions, we herein explore rate acceleration under ball-milling conditions while the conventional solution-state synthesis suffer from low reactivity. The solvent-free mechanochemical polymerization of trimethylene carbonate using the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) are examined herein. The polymerizations under ball-milling conditions exhibited significant rate enhancements compared to polymerizations in solution. A number of milling parameters were evaluated for the ball-milling polymerization. Temperature increases due to ball collisions and exothermic energy output did not affect the polymerization rate significantly and the initial mixing speed was important for chain-length control. Liquid-assisted grinding was applied for the synthesis of high molecular weight polymers, but it failed to protect the polymer chain from mechanical degradation.

scholarly journals Renal sodium-potassium adenosine triphosphatase. Optical localization and x-ray microanalysis.

1975 ◽  
Vol 23 (11) ◽  
pp. 828-839 ◽  
Author(s):  
R Beeuwkes ◽  
S Rosen
Keyword(s):  
Atpase Activity ◽  
Electron Probe ◽  
Sequential Analysis ◽  
Relative Sensitivity ◽  
Initial Reaction ◽  
Initial Product ◽  
Sodium Potassium ◽  
Nitrophenyl Phosphate ◽  
Hydrolysis Of ◽  
Convoluted Tubules

The distribution of sodium-potassium adenosine triposphatase (Na-K-ATPase) activity in kidney sections has been studied by a method based on the hydrolysis of p-nitrophenyl phosphate in alkaline medium containing dimethyl sulfoxide. The products at each stage in the reaction sequence have been subjected to electron probe microanalysis. The initial product was identified as a mixture of KMgPO4 and Mg(PO4)2, and sequential analysis demonstrated the linearity of conversion of this product to a visible form. In human, rabbit and rat kidneys the distribution of activity was found to be essentially identical, with highest levels located in thick ascending limbs and distal convoluted tubules. The initial reaction was completely potassium dependent and was inhibited by ouabain in concentrations reflecting the relative sensitivity of microsomal Na-K-ATPase in each species. Measurement of initial product phosphorus by means of the electron probe is presented as a practical technique for direct quantitation of Na-K-ATPase activity in identified tubule segments.

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