The effect of colonization with the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol.& Gerd.) Gerdemann & Trappe on the growth and physiology of NaCl-stressed maize plants ( Zea mays L. cv. Yedan 13) was examined in the greenhouse. Maize plants were grown in sand with 0 or 100 mM NaCl and at two phosphorus (P) (0.05 and 0.1 mM) levels for 34 days, following 34 days of non-saline pre-treatment. Mycorrhizal plants maintained higher root and shoot dry weights. Concentrations of chlorophyll, P and soluble sugars were higher than in non-mycorrhizal plants under given NaCl and P levels. Sodium concentration in roots or shoots was similar in mycorrhizal and non-mycorrhizal plants. Mycorrhizal plants had higher electrolyte concentrations in roots and lower electrolyte leakage from roots than non-mycorrhizal plants under given NaCl and P levels. Although plants in the low P plus AM fungus treatment and those with high P minus AM fungus had similar P concentrations, the mycorrhizal plants still had higher dry weights, soluble sugars and electrolyte concentrations in roots. Similar relationships were observed regardless of the presence or absence of salt stress. Higher soluble sugars and electrolyte concentrations in mycorrhizal plants suggested a higher osmoregulating capacity of these plants. Alleviation of salt stress of a host plant by AM colonization appears not to be a specific effect. Furthermore, higher requirement for carbohydrates by AM fungi induces higher soluble sugar accumulation in host root tissues, which is independent of improvement in plant P status and enhances resistance to salt-induced osmotic stress in the mycorrhizal plant.

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The electromagnetic backscattering properties of an infinite conducting cylinder coated with a lossless dielectric layer of thickness comparable to a wavelength is investigated both theoretically and experimentally. The theoretical problem is first formulated with three regions of arbitrary constants and then reduced to the specific cases. The experimental investigation utilizes the parallel-plate-region technique modified to permit the application of the Doppler shift principle. The scattering obstacle is set in motion in the presence of a plane-wave electromagnetic field in the parallel-plate region, and the detected Doppler signal is directly proportional to the backscattered field of the obstacle in question. The theoretical and experimental results are in excellent agreement.

The hydrous calcium carbonate mineral ikaite (CaCO 3 .6H 2 O) forms in nature at low temperature in carbonate-and Ca-rich waters. Ikaite crystallizes in the spacegroup C2/c, and consists of CaCO 3 .6H 2 O units with Ca ions coordinated by eight oxygens, six from H 2 O and two from the carbonate group. Hydrogen bonding links CaCO 3 .6H 2 O moieties to form the crystal structure.We have used synchrotron X-ray powder diffraction at T = 243 K to refine the monoclinic structure of ikaite, and have measured unit-cell parameters of ikaite between T = 114 K and T = 293 K. Anisotropic thermal expansion in ikaite is evident, with the smallest relative increase occurring along the b direction parallel to 2-fold axes. The contribution of hydrogen bonding to thermal expansion is assessed by comparison of our data with previously published data for deuterated ikaite, ice and gypsum. Ikaite exhibits a coefficient of volume expansion intermediate between that of ice (Ih) and of deuterated gypsum (CaSO 4 .2D 2 O) between T = 114 K and T = 293 K.

A new beamline (MPW6.2) has been designed and built for the study of materials during processing where three synchrotron techniques, SAXS, WAXS and XAS, are available simultaneously. It has been demonstrated that Rietveld refinable data can be collected from silicon SRM 640b over a 60 degrees range in a time scale of 1 s. The data have been refined to a chi(2) of 2.4, the peaks fitting best to a Pearson VII function or with fundamental parameters. The peak halfwidths have been found to be approximately constant at 0.06 degrees over a 120 degrees angular range indicating that the instrumental resolution function has matched its design specification. A quantitative comparison of data sets collected on the same isotactic polypropylene system on MPW6.2 and DUBBLE at the ESRF shows a 17% improvement in angular resolution and a 1.8 improvement in peak-to-background ratio with the RAPID2 system; the ESRF data vary more smoothly across detector channels. The time-dependent wide-angle XRD was tested by comparing a hydration reaction of gypsum-bassanite-anhydrite with energy-dispersive data collected on the same system on the same time scale. Three sample data sets from the reaction were selected for analysis and gave an average chi(2) of 3.8. The Rietveld-refined lattice parameters are a good match with published values and the corresponding errors show a mean value of 3.3 x 10(-4). The data have also been analysed by the Pawley decomposition phase-modelling technique demonstrating the ability of the station to quickly and accurately identify new phases. The combined SAXS/WAXS capability of the station was tested with the crystallization and spinodal decomposition of a very dilute polymer system. Our measurements show that the crystallization of a high-density co-polymer (E76B38) as low as 0.5% by weight can be observed in solution in hexane. The WAXS and SAXS data sets were collected on the same time scale. The SAXS detector was calibrated using a collagen sample that gave 30 orders of diffraction in 1 s of data collection. The combined XRD and XAS measurement capability of the station was tested by observing the collapse and re-crystallization of zinc-exchanged zeolite A (zeolite Zn/Na-A). Previous studies of this material on station 9.3 at the SRS were compared with those from the new station. A time improvement of 38 was observed with better quality counting statistics. The improved angular resolution from the WAXS detector enabled new peaks to be identified.