Dynamics of water, hydrated-ions and charged polymers in highly-confined films, and their role in friction modification

2003 ◽  
Vol 790 ◽  
Author(s):  
Jacob Klein ◽  
Uri Raviv ◽  
Susan Perkin ◽  
Nir Kampf ◽  
Suzanne Giasson
Keyword(s):  
Polymer Brushes ◽  
Aqueous Media ◽  
Free Water ◽  
Aqueous Salt Solution ◽  
Ball Bearings ◽  
High Concentration ◽  
Charged Surfaces ◽  
Hydrated Ions ◽  
Charged Polymer ◽  
The One

ABSTRACTRecent studies have revealed that, in contrast to non-associating liquids such as oils or organic solvents, salt-free water retains a viscosity close to its bulk value even when confined to films thinner than some 3 nm, indeed down to only one or two monolayers thick [1,2]. For the case of high concentration aqueous salt solution compressed down to subnanometer films between charged surfaces, the trapped hydrated ions serve to act as molecular ball-bearings, sustaining a large load while remaining very fluid under shear [3]. This behaviour is attributed to the tenacity of the hydration sheaths together with their rapid relaxation time. Finally, a very recent study [4] has shown that when charged polymer brushes in aqueous media are compressed and slid past each other, they provide a lubrication that is considerably superior to that afforded by neutral brushes: This is attributed on the one hand to the resistance to mutual interpenetration of the chains due to entropic barriers in the good-solvent conditions, and, on the other hand, to the hydration-sheaths on the charged polymer segments which can act – as noted above – as molecular ball-bearings.

scholarly journals High concentration Brownian coagulation in jet flow using two enhancement formulations

2012 ◽  
Vol 16 (5) ◽  
pp. 1519-1523
Author(s):  
Pei-Feng Lin ◽  
Di-Chong Wu ◽  
Ze-Fei Zhu
Keyword(s):  
Volume Fraction ◽  
Taylor Series Expansion ◽  
Expansion Method ◽  
High Volume ◽  
Jet Flow ◽  
High Concentration ◽  
Brownian Coagulation ◽  
Planar Jet ◽  
Ultra Fine Particle ◽  
The One

Ultra-fine particle coagulation by Brownian motion at high concentration in planar jet flow is simulated. A Taylor-Series Expansion Method of Moments is employed to solve the particle general dynamic equation. The volume fraction gets high value, very closes to that at the nozzle exit. As the vortex pairing develops, the high volume fraction region rolls out and mixes with the low value region. The enhancement factor given by Trzeciak et al. will be less than one at some specific outer positions, which seems to be less accurate than the one given by Heine et al.

INBORN ERROR OF HISTIDINE METABOLISM

PEDIATRICS ◽  
1962 ◽  
Vol 29 (5) ◽  
pp. 714-728
Author(s):  
H. Ghadimi ◽  
M. W. Partington ◽  
A. Hunter
Keyword(s):  
Ferric Chloride ◽  
Urocanic Acid ◽  
High Concentration ◽  
Normal Children ◽  
Total Lack ◽  
Normal Urine ◽  
One Year ◽  
The One ◽  
Blue Eyes ◽  
Derivatives Of

A 3-year-old girl with fair hair and blue eyes came under observation because of speech retardation. The patient was given a phenylalanine-free diet, since persistently positive urine tests with ferric chloride and reagent strips (Phenistix) were strongly suggestive of phenylketonuria. On further investigation she was found to be suffering from a totally different and not heretofore recognized condition, the salient features of which were an abnormally high concentration of histidine in the blood and an excessive output of histidine in the urine. The child's sister, one year older, presented the same metabolic anomaly. In each case both the concentration of histidine in plasma and the daily output were directly related to the amount of protein in the diet; but even at their lowest levels they greatly exceeded those of normal children of the same age. An oral load of histidine was followed by an increase of histidine in plasma much higher and more prolonged than that observed in controls, and by the excretion of a much larger fraction of the ingested dose. The urine of each sister contained not only excessive amounts of histidine but also notable quantities of imidazole-pyruvic, imidazole-acetic, and imidazole-lactic acid, histidine derivatives of which normal urine contains only traces. It is concluded that in the two sisters the normally predominant pathway of histidine catabolism, which leads through urocanic acid to glutamic acid, was partially or completely blocked. Since, even after histidine loading, the urines never contained detectable amounts of urocanic acid, the block must precede the formation of that substance. The condition presented is therefore due primarily to a deficiency or total lack of histidine-alpha-deaminase; the enzyme which converts histidine to urocanic acid. As a result of this defect histidine is forced to take the alternative but less efficient pathway which begins with its transamination to imidazole-pyruvic acid. This substance is the one responsible for positive reactions in the ferric chloride and Phenistix tests. All urine specimens examined, whether from the patient or from normal controls, contained considerable quantities of an unidentifiable imidazole compound ("X"), which does not appear to have been previously reported. The existence of this substance may call for some modification of current concepts of histidine metabolism in man.

Diammonium Hydrogen Phosphate: An Efficient and Versatile Catalyst for the One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives in Aqueous Media.

ChemInform ◽  
2007 ◽  
Vol 38 (41) ◽  
Author(s):  
Saeed Balalaie ◽  
Morteza Bararjanian ◽  
Masoumeh Sheikh-Ahmadi ◽  
Shohreh Hekmat ◽  
Peyman Salehi
Keyword(s):  
Aqueous Media ◽  
Hydrogen Phosphate ◽  
One Pot ◽  
Diammonium Hydrogen Phosphate ◽  
One Pot Synthesis ◽  
The One ◽  
Diammonium Hydrogen

The one-pot synthesis of core/shell/shell CdTe/CdSe/ZnSe quantum dots in aqueous media for in vivo deep tissue imaging

2011 ◽  
Vol 21 (9) ◽  
pp. 2877 ◽  
Author(s):  
Shohei Taniguchi ◽  
Mark Green ◽  
Sarwat B. Rizvi ◽  
Alexander Seifalian
Keyword(s):  
Quantum Dots ◽  
Aqueous Media ◽  
Tissue Imaging ◽  
Core Shell ◽  
Deep Tissue ◽  
One Pot ◽  
One Pot Synthesis ◽  
Deep Tissue Imaging ◽  
The One

scholarly journals Spreading of chemical substance after its accidental spillage onto the soil surface under unsaturated conditions and variable porosity

2019 ◽  
pp. 41-44
Author(s):  
Olena Kozhushko ◽  
Petro Martyniuk
Keyword(s):  
Mathematical Model ◽  
Soil Moisture ◽  
Soil Profile ◽  
Moisture Transport ◽  
Soil Surface ◽  
Chemical Substance ◽  
High Concentration ◽  
Solute Transfer ◽  
Variable Porosity ◽  
The One

In this paper we study a mathematical model of soil moisture transport with variable porosity. The problem is set for the case of highly concentrated solute spilled onto soil surface. We investigate the way solute transfer, adsorption of contaminant by soil particles and variable porosity influence infiltration of solute into the soil profile. For that purpose, two models are used: a classical one and the one with consideration of mentioned factors. By comparing the results of both models, we established that high concentration of solute causes moisture transport to transpire more slowly, and the pollutant to remain on the soil surface for longer time. Numerical results indicate that porosity can vary considerably under the conditions of intensive contamination with salts.

Binding of ionic surfactants to charged polymer brushes grafted onto porous substrates

2002 ◽  
Vol 954 (1-2) ◽  
pp. 89-97 ◽  
Author(s):  
Haruhiko Ogawa ◽  
Kazuyuki Sugita ◽  
Kyoichi Saito ◽  
Min Kim ◽  
Masao Tamada ◽  
...  
Keyword(s):  
Polymer Brushes ◽  
Ionic Surfactants ◽  
Charged Polymer ◽  
Porous Substrates

Hyponatremia in the rat in the absence of positive water balance.

1997 ◽  
Vol 8 (4) ◽  
pp. 524-529
Author(s):  
M Gowrishankar ◽  
C B Chen ◽  
S Cheema-Dhadli ◽  
A Steele ◽  
M L Halperin
Keyword(s):  
Water Balance ◽  
Isotonic Saline ◽  
Extracellular Fluid ◽  
Free Water ◽  
Control Group ◽  
High Concentration ◽  
Additional Control ◽  
Two Factors ◽  
Negative Balance ◽  
Usual Diet

The purpose of this report is to determine the mechanisms that lead to hyponatremia when isotonic saline was the only fluid infused into rats given antidiuretic hormone (ADH), and what might minimize the degree of this hyponatremia. Normal rats were deprived of food and water for the 24-hr study period. They received an infusion of isotonic saline to expand their extracellular fluid (ECF) volume with and without exogenous ADH administration (N = 8 in each of the four groups). Similar studies were also carried out in 32 rats fed a low electrolyte diet for 72 hr before the experiment. An additional control group was fed the low electrolyte diet supplemented with sodium (Na), potassium (K), and chloride (Cl). Hyponatremia developed over 24 hr in rats fed their usual diet if treated with ADH and isotonic saline (fall, 13 +/- 2 mM, P < 0.01). The hyponatremia was caused by negative balance for Na + K salts. Hyponatremia did not develop after the saline + ADH treatment if rats were pretreated for 3 days with a low electrolyte diet. Two factors were required to develop this hyponatremia--generation of electrolyte-free water as a result of the excretion of a large quantity of Na + K salts at a high concentration in the urine, and prevention of the excretion of this electrolyte-free water by ADH. Increasing the avidity for Na reabsorption by the kidney prevented this type of hyponatremia from developing.

scholarly journals Feeding preference of the shredder Phylloicus sp. for plant leaves of Chrysophyllum oliviforme or Miconia chartacea after conditioning in streams from different biomes

2019 ◽  
Vol 79 (1) ◽  
pp. 22-28 ◽  
Author(s):  
D. F. Reis ◽  
M. M. D. Machado ◽  
N. P. Coutinho ◽  
J. V. Rangel ◽  
M. S. Moretti ◽  
...  
Keyword(s):  
Atlantic Forest ◽  
Chemical Elements ◽  
Abundant Species ◽  
Feeding Preference ◽  
High Concentration ◽  
Mata Atlântica ◽  
Leaf Discs ◽  
Forest Stream ◽  
Mata Atlantica ◽  
The One

Abstract Macroinvertebrate shredders consume preferably leaves conditioned by fungi and bacteria which offer greater palatability to them. Plant species in Cerrado present high concentration of chemical elements such as lignin and cellulose, phenols and tanins thus making them less attractive for shredders consumption and limiting the palatability. This study aimed to evaluate the feeding preference of a macroinvertebrate shredder of the genus Phylloicus for plant material from two different biomes (Cerrado and Mata Atlântica), after conditioning in a stream of Mata Atlântica and observing their physical and chemical characteristics. Senescent leaves were collected, monthly from the litterfall of riparian vegetation in a 500 m stretch of a stream in each biome from August 2014 to January 201. The most abundant species in each stream was selected for the experiment. The experimental design consisted in with two treatments. The first (T1) comprised leaf discs from Chrysophyllum oliviforme (Cerrado species) together with leaf discs of Miconia chartacea (Atlantic Forest species) which were conditioned in the Atlantic Forest stream. The second treatment (T2) involved leaf discs of Miconia chartacea conditioned in Mata Altlântica and Cerrado streams. Both tests had showed significant differences between the two treatments (T1 and T2). For T1, there was consumption of M. chartacea leaf discs by Phylloicus sp., but there was no consumption of C. oliviforme discs. For T2, there was preference for M. chartaceae leaves conditioned in a stream of Mata Atlântica than in Cerrado stream. The results showed that Phylloicus sp., had presented preference for food detritus of the Mata Antlântica biome and rejection to the one from Cerrado biome.

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