Release and characterization of single side chains of white cabbage pectin and their complement‐fixing activity

A mixture of single side chains from white cabbage pectin were obtained by anion exchange chromatography after applying mild chemical conditions promoting β‐elimination. These pectin fragments were characterized by their molecular weight distribution, sugar composition, ¹³C‐NMR, and MALDI‐TOF‐MS analysis. These analyses revealed that the large oligosaccharides released by β‐eliminative treatment were composed of α‐1,5 linked arabinosyl residues with 2‐ and 3‐linked α‐arabinosyl side chains, and, or β‐1,4 linked galactosyl side chains. Fractions were tested for complement‐fixing activity in order to determine their interaction with the complement system. These results strongly indicated that there was a minimal unit size responsible for the complement‐fixing activity. Neutral pectin fragments (?8 kDa) obtained from β‐elimination were inactive in the complement system, although they contained a sugar composition previously shown to be highly active. Larger pectin fragments (?17 kDa) retained some activity, but much lower than polymers containing rhamnogalacturonan type 1 (RGI) structures isolated from the same source. This implied that structural elements containing multiple side chains is necessary for efficient complement‐fixing activity.     

Bath chemistry and aluminum cell performance—Facts,fictions, and doubts

This article examines the relationship between bath chemistry and aluminum cell performance together with facts, fictions, and doubts arising from data available in the literature. An earlier trend toward more low-ratio baths now appears to have stopped at about 12% AIF₃, which is a typical bath composition used in modern, high-amperage cells. Widely different bath compositions are still used in older cells. Current controversies concern the effect of the alumina content in the bath on current efficiency and energy consumption, the true effect of LiF-containing modified baths, and the optimum content of AIF₃. Recent current efficiency data for lithium-modified low-ratio baths are discussed, together with the expected future development of bath chemistry in aluminum electrolysis cells. Further changes in bath composition can contribute to small, but significant improvements in cell performance, even in the best modern cells.     

Pectin isolated from white cabbage--structure and complement-fixing activity

This study was done to investigate whether white cabbage contained polysaccharides with immunostimulatory activity using the complement-fixing test as an indicator. The main polysaccharide isolated was of pectin nature. Methanolysis and (13)C-NMR showed that the polymers consisted of highly esterified alpha-galactopyranoside (alpha-GalpA), significant amounts of alpha-arabinose furanoside (alpha-Araf), beta-Galp and lesser amounts of rhamnose in the pyranose form (Rhap) and xylose in the pyranose form (Xylp). Linkage analyses showed that the alpha-GalpA residues were mainly 1,4-linked with small amounts of 1,3,4-linkages. The alpha-Araf residues were mainly terminally (t)- and 1,5-linked, whereas beta-Galp was t-, 1,3-, 1,6-, and 1,3,6-linked. Positive Yariv reaction indicated polymers with arabinogalactan type 2 like structures. alpha-Rhap was mainly present as 1,2- and 1,2,4-linked residues and Xylp was t- and 1,4-linked. The molecular weight varied greatly and was from 10 to 150 kDa. Cabbage polymers had biological activity and this complement-fixing activity was greatly affected by hydrolytic removal of Araf from pectic side chains.     

Characteristics and Nature of Metal Fog in Molten Salts

In this paper are reported the characteristicsand nature of metal fog in molten cryolite-aluminamixtures on the basis of laboratory experiments andquantum chemistry studies.The metal fog is thefinely divided metal particles in the molten salts,and it dissolves partly in the molten cryolite to formatomic clusters,such as(Al_nNa_m)~(x+) type.     

Screening of acrylamide contents in potato crisps using process variable settings and near-infrared spectroscopy

In order to study the formation of acrylamide in potato crisps during processing, an experimental design was set up. The design variables were drying time (6 levels), frying temperature (2 levels) and frying time (8 levels). The design contained 36 samples, which were analysed for acrylamide contents using LC high-resolution mass spectroscopy (LC-HRMS), and fat contents using the Soxhlet apparatus. Prior to analysis, all potato crisp samples were ground and analysed on an NIRSystems 6500 near-infrared (NIR) spectrometer. The acrylamide contents were modelled by: (i) design variables using multiple linear regression, (ii) NIR spectra using partial least squares regression (PLSR) and (iii) design variables and NIR spectra in combination using a novel technique combining least squares regression on the former, and PLSR on the latter. The results showed that the NIR spectra alone or in combination with the design variables gave better prediction models for acrylamide than the design variables alone. This implies that the spectra contain chemical information that is not purely a result of the processing variables that were investigated in this experiment. NIR spectroscopy is proposed as a possible tool for screening and identification of potato crisps with a high acrylamide content.     

Electrical Conductivity of Cryolite Melts

JOM - This paper proposes an equation for the electrical conductivity of multicomponent cryolite-based mixtures. The equation is based on a physical model which assumes that the conductivity is...     

The possible reduction of alumina to aluminum using hydrogen

Theoretical considerations based on published thermodynamic data show that condensed aluminum should not be formed by direct reaction between hydrogen and alumina. Nevertheless, laboratory experiments by the authors and observations reported by others in the literature have led to the hypothesis that hydrogen dissolved in molten aluminum can possibly reduce alumina to aluminum at high temperature (700–1,700°C). For more information, contact H. Kvande, Hydro Aluminium, N-0246 Oslo, Norway; telephone 47 22 73 9155; fax 47 22 73 7778; e-mail Halvor.Kvande@hydro.com.