Library

Notes: Collagen is an important component for cosmetic formulation, where it is an effective natural humectant with high substantivity. Commercial collagen preparations have a wide range of properties. In the present study, various techniques have been used to examine three distinct commercial collagens that illustrate the range of properties that are available. The usefulness of the various techniques for assessing collagen quality and batch-to-batch variation is discussed. The results indicate that there are several simple, cheap and effective methods such as gel electrophoresis that provide excellent information on collagen quality. The appropriate selection of tests allows informed decisions on the choice of which collagen preparation to use in providing the desired functionality and shelf life of a formulation.

Notes: Broad and important progress in plasma tests, theory, new experiments, and future visions of the spherical torus (ST, or very low aspect ratio tokamaks) have recently emerged. These have substantially improved our understanding of the potential properties of the ST plasmas, since the preliminary calculation of the ST magnetohydrodynamic equilibria more than a decade ago. Exciting data have been obtained from concept exploration level ST experiments of modest capabilities (with major radii up to 35 cm), making important scientific contributions to toroidal confinement in general. The results have helped approval and construction of new and/or more powerful ST experiments, and stimulated an increasing number of theoretical calculations of interest to magnetic fusion energy. Utilizing the broad knowledge base from the successful tokamak and advanced tokamak research, a wide range of new ST physics features has been suggested. These properties of the ST plasma will be tested at the 1 MA level with major radius up to ∼80 cm in the new proof of principle devices National Spherical Torus Experiment (NSTX, U.S.) [M. Peng et al., European Conf. Abst. 22C, 451 (1998); S. M. Kaye et al., Fusion Technol. 36, 16 (1999); M. Ono et al., "Exploration of Spherical Torus Physics in the NSTX Device," 17th IAEA Fusion Energy Conf., paper IAEA-CN-69/ICP/01 (R), Yokohama, Japan (1998)], Mega Ampere Spherical Tokamak (MAST, U.K.) [A. C. Darke et al., Fusion Technol. 1, 799 (1995); Q. W. Morris et al., Proc. Int. Workshop on ST (Ioffe Inst., St. Petersburg, 1997), Vol. 1, p. 290], and Globus-M (R.F.) [V. K. Gusev et al., European Conf. Abst. 22C, 576 (1998)], which have just started full experimental operation. New concept exploration experiments, such as Pegasus (University of Wisconsin) [R. Fonck and the PEGASUS Team, Bull. Am. Phys. Soc. 44, 267 (1999)], Helicity Injected Tokamak-II (HIT-II, University of Washington) [T. R. Jarboe et al., Phys. Plasmas 5, 1807 (1998)], and Current Drive Experiment-Upgrade (CDX-U, Princeton Plasma Physics Laboratory) [M. Ono et al., Proceedings of the 16th International Conference on Fusion Energy (IAEA, Vienna, 1997), Vol. 2, p. 71] and other experiments in Japan and Brazil, etc., present additional opportunities for important progress. This tutorial paper summarizes our understanding and projections of the physics of the ST plasmas, the investigation of which will hopefully bring new enthusiasm and advancements for fusion energy science research in the U.S. and the world. © 2000 American Institute of Physics.

Notes: Tensile stress induced by backside CoSi2 films on a silicon substrate has been found to enhance the growth of C54–TiSi2 on (001)Si. In contrast, compressive stress induced by backside oxide films on the silicon substrate was found to retard significantly the growth of C54–TiSi2 on (001)Si. For Ti on stressed (001)Si after rapid thermal annealing at 800 °C for 30 s, the thickness of the C54– TiSi2 films was found to increase and decrease with the tensile and compressive stress levels, respectively. The retarded growth is attributed to the hindrance of the migration of Si through the Ti/Si interface by the compressive stress. On the other hand, the presence of tensile stress promotes the Si diffusion to facilitate the formation of Ti silicide thin films. © 1999 American Institute of Physics.

Notes: Abscisic acid (ABA) improves the sink strength by promoting the phloem unloading and regulating the assimilate metabolism in the economic sink organs of crops, although its mechanism remains unknown. The present experiment, using the techniques of the in vivo injection of ABA into the intact apple fruit attached to a growing apple tree and the in vivo incubation of the fruit tissue in the ABA-contained medium, showed that ABA strongly activated the fruit ATPase especially P-ATPase, of which the activity was doubled by ABA treatment. This ATPase activation was shown to be in vivo tissue-dependent. The ABA-induced P-ATPase activation was fruit developmental stage-, ABA dose-, medium pH- and incubation time-dependent. Physiological active (+)ABA was shown more effective to stimulate P-ATPase activity than (+/–)ABA, and two ABA analogues (–)ABA and trans-ABA, had no effect on P-ATPase activation, indicating that only physiologically active cis(+)ABA can induce the enzyme activation, and so the ABA-induced effects are stereospecific. The protein synthesis inhibitor cycloheximide was shown to have no effect on P-ATPase activation by ABA, suggesting that synthesis of new proteins was not involved in the enzyme activation. The cytochemical assay revealed that P-ATPase was activated by ABA in both the phloem and its surrounding flesh parenchyma cells, and that the most strongly P-ATPase activation was observed in the plasma membrane of sieve element/companion cell complex. These data suggest that the improvement of phloem unloading by ABA previously reported in this fruit as in other crop sink organs may be attributed, at least partly, to the ABA-induced ATPase activation especially in phloem cells.

Notes: A restriction fragment length polymorphism (RFLP) linkage map of Sorghum bicolor (L.) Moench was constructed in a population of 137 F6-8 recombinant inbred lines using sorghum, maize, oat, barley and rice DNA clones. The map consists of 10 linkage groups (LGs) and 323 markers, 247 of which (76.5%) were ordered at a LOD score ≥ 3.0. The LGs comprise from 61 (LG A) to 13 markers (J), which range in length from 205 (A) to 55 cM (J) and have a combined total length of 1347 cM. Highly significant distorted segregation was detected at all of the 38 loci in a 103-cM segment of LG A, the allelic ratios in the segment ranging from approximately 3:1 (one end) to 19:1 (middle) to 2:1 (other end). Duplicated loci located in different LGs have been mapped with 55 of the 295 DNA probes used in the study (18.6%). The distribution of these loci does not provide support for the hypothesis that Sorghum bicolor (L.) Moench is of tetraploid origin. Comparison of the map with RFLP maps of maize, rice, and oat produced evidence for sorghum-maize LG rearrangements and homoeologies not reported previously, including evidence that: (1) a segment of maize 5L and a segment of 5S may be homoeologous to sorghum LGA; (2) maize LGs 4 and 6 are partly homoeologous to sorghum LGE; (3) the short arm of maize LG 2 is partly homoeologous to sorghum LGF; (4) maize LG 4 may be partly homoeologous to sorghum LG G; (5) maize LG 5 and sorghum LG G contain a larger amount of homoeologous genetic material than previously indicated; and (6) a short segment of maize LG 1 may be homoeologous to a short segment of sorghum LG I.