Home  About us  Contact
 

Solution System (solution + system)

Distribution by Scientific Domains
Polymers and Materials Science60%

Selected Abstracts

Gelation Rate Modulation of an , -Cyclodextrin and Poly(ethylene glycol)-Grafted Hyaluronic Acid Solution System by Inclusion Complexation of a Microphase-Separated Structure

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2004
Tsuyoshi Nakama
Abstract Summary: The gelation rate of a poly(ethylene glycol)-grafted hyaluronic acid (PEG- graft -HA) solution with adding , -CD was investigated in term of the microphase separation between the grafted PEG and HA. The gelation rate of PEG- graft -HA exhibiting the microphase-separated structure was two times higher than that of PEG- graft -HA showing a homogeneous miscible state. The formation of microphases by PEG- graft -HA contributes to its rapid gelation upon the addition of , -CDs. [source]

Mass Balances in Porous Foods Impregnation

JOURNAL OF FOOD SCIENCE, Issue 9 2001
V. Roa
ABSTRACT: A simple model based on mass balance equations is proposed for prediction of the final mass and composition of products subjected to vacuum impregnation. It was applied to some tropical fruits in a fruit-sucrose solution system. The phenomenon can be described in terms of volumetric fraction of impregnating solution as the basic modeling parameter, instead of effective porosity. To use the equations of the model, only routine laboratory equipment and simple experiments are required. Prediction of the final weight of impregnated fruit was accomplished with an average absolute error of 2 to 3%, while in final composition of the fruit (total solids), it was 5.7 %. [source]

Homogenous Synthesis of Hydroxyethylcellulose in NaOH/Urea Aqueous Solution

MACROMOLECULAR BIOSCIENCE, Issue 1 2006
Jinping Zhou
Abstract Summary: Hydroxyethylcellulose (HEC) was synthesized by a fully homogenous method from cellulose in 7.5 wt.-% NaOH/11 wt.-% urea aqueous solutions under mild conditions. HEC samples were characterized with NMR, SEC-LLS, solubility, and viscosity measurements. The MS and DS values of the obtained HEC samples are in the range from 0.54 to 1.44 and 0.45 to 1.14, respectively, and the relative DS values at C-2 and C-6 hydroxyl groups are slightly higher than those at C-3 hydroxyl groups. HEC samples are soluble in water starting from a MS of 0.57 and DS of 0.49, which display high viscosity in aqueous solutions. Moreover, a NaOH/urea aqueous solution is a stable system for cellulose etherification. In this way, we could provide a simple, pollution-free, and homogeneous aqueous solution system for synthesizing cellulose ethers. 13C NMR spectra of acetylated HEC (a) in CDCl3 at 40,°C and (b) in DMSO- d6 at 100,°C. [source]

Aerenchyma formation and radial O2 loss along adventitious roots of wheat with only the apical root portion exposed to O2 deficiency

PLANT CELL & ENVIRONMENT, Issue 10 2003
A. I. MALIK
ABSTRACT This study investigated aerenchyma formation and function in adventitious roots of wheat (Triticum aestivum L.) when only a part of the root system was exposed to O2 deficiency. Two experimental systems were used: (1) plants in soil waterlogged at 200 mm below the surface; or (2) a nutrient solution system with only the apical region of a single root exposed to deoxygenated stagnant agar solution with the remainder of the root system in aerated nutrient solution. Porosity increased two- to three-fold along the entire length of the adventitious roots that grew into the water-saturated zone 200 mm below the soil surface, and also increased in roots that grew in the aerobic soil above the water-saturated zone. Likewise, adventitious roots with only the tips growing into deoxygenated stagnant agar solution developed aerenchyma along the entire main axis. Measurements of radial O2 loss (ROL), taken using root-sleeving O2 electrodes, showed this aerenchyma was functional in conducting O2. The ROL measured near tips of intact roots in deoxygenated stagnant agar solution, while the basal part of the root remained in aerated solution, was sustained when the atmosphere around the shoot was replaced by N2. This illustrates the importance of O2 diffusion into the basal regions of roots within an aerobic zone, and the subsequent longitudinal movement of O2 within the aerenchyma, to supply O2 to the tip growing in an O2 deficient zone. [source]

Electrical Properties of Gadolinium,Europium Zirconate Ceramics

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2010
Xiao-Liang Xia
(Gd1,xEux)2Zr2O7 (0,x,1.0) ceramics are prepared via a solid-state reaction process at 1973 K for 10 h in air. (Gd1,xEux)2Zr2O7 (0.2,x,1.0) ceramics exhibit an ordered pyrochlore-type structure; however, Gd2Zr2O7 has a disordered defect fluorite-type structure. Raman spectroscopy analysis indicates that the degree of structural ordering increases with the increase of Eu content. The electrical properties of (Gd1,xEux)2Zr2O7 ceramics are investigated using complex impedance spectroscopy over a frequency range of 0.1 Hz to 20 MHz from 623 to 923 K. Electrical conductivity obeys the Arrhenius equation. Both the activation energy and the preexponential factor for grain conductivity decrease with increasing europium content from Gd2Zr2O7 (x=0) to Eu2Zr2O7 (x=1.0). The measured electrical conductivity of (Gd1,xEux)2Zr2O7 ceramics increases with increasing Eu content and temperature. Electrical conductivity of the pyrochlore-type materials is higher than that of the defect fluorite-type material in (Gd1,xEux)2Zr2O7 solid solution systems. The electrical conductivity of (Gd0.4Eu0.6)2Zr2O7 is almost independent of oxygen partial pressure from 1.0 × 10,4 to 1.0 atm. The high ionic transference number of (Gd0.4Eu0.6)2Zr2O7 ceramic at different temperatures proves that conduction is purely ionic with negligible electronic contribution. [source]