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Rice is an important produced cereal in the world. We evaluated the effect of salt compositions including NaCl and Na2SO4 on suberin lamellae as a major barrier to radial ion and water movements in two rice genotypes representing contrasting salt tolerance levels under salinity stress. Two rice genotypes, Fajr as salt tolerant and Khazar as salt sensitive, were transplanted in sand culture under glasshouse condition. Rice seedlings were treated with five salt compositions including NaCl, Na2SO4, 1 :1, 1 :2, and 2:1 molar ratios for 40 days. It was proven that suberin lamellae in endodermis of root cell wall were thickened with Na2SO4 treatment. The results demonstrated that the number of passage cells was higher in Fajr genotype than that in Khazar genotype under saline condition. Calcium concentration in root tissue decreased as the SO4 2- concentration in rootmedia increased. It can be concluded that Fajr genotype is able to keep some passage cells open to maintain Ca2+ uptake. The Ca2+/Na+ ratio in shoot tissue can be also a reliable index for the early recognition of salt stress in these rice genotypes. [ABSTRACT FROM AUTHOR]

Plant cells accumulate praline as an osmoprotectant to conserve osmotic stability and prevent damage. However, the accumulation of proline may not be associated with tolerance to salinity. This study considered the influences of NaCl and Na2SO4 compositions, at different concentrations, on seed germination and accumulation of proline in eleven rice genotypes. Rice seeds were grown in petri dishes in the laboratory and treated with distilled water as a control and NaCI and Na2SO4 (1:1 molar concentration ratio) at 2.5, 5.0, 7.5 and 10 dS m-1 electrical conductivity for 14 days. The mean germination time (MGT) was positively affected by the increase in the concentration of salt. Conversely, there was a negative relationship between germination index (GI) and salt concentration. Shirodi, Fajr, and Shafag can be classified into salt tolerant group, while Tarom-e-Hashemi was identified as salt susceptible, based on MGT and GI. Slight changes were recorded within dry weight and water content of seedlings at different salt levels. The maximum accumulation of proline was observed at 5 dS m-1 salt concentration. No relationship was established between the accumulation of proline and the growth parameters. [ABSTRACT FROM AUTHOR]

Scintillators like CsI(Na), having double-exponential decay times, typically cannot be used in high-count rate applications due to the complicated pulse shapes created by the convolution of their light output decay curves with the decay constant of charge integrating preamplifiers. We present here a novel digital filtering algorithm that is capable of using CsI(Na) at input count rates exceeding 250 kcps, while still achieving good energy resolution. We used a 2.54 cm diameter and 2.54 cm long CsI(Na) crystal, whose scintillation light can be best described by a short component with a 550 ns decay time and a long component with a 4 μs decay time. The crystal was coupled to a 2.86 cm diameter photomultiplier tube. The digital filtering algorithm was implemented in XIA's all-digital Polaris spectrometer, in which five running sums were captured from each digitized scintillation pulse and the Polaris's on-board DSP read these sums and used a set of precomputed coefficients to reconstruct the pulse's total light output as a measure of the deposited energy. The algorithm was tested at different input count rates, ranging from 19 kcps to 270 kcps using a 1 mCi137 Cs source. The energy resolution (full-width at half-maximum) at 662 keV was 10.7% at 19 kcps and 11.7% at 270 kcps with a filter rise time of 1.0 μs, and improved to 7.0% and 8.4%, respectively, with a filter rise time of 3.2 μs. The energy peak shifted by less than 0.3% for input count rates below the maximum throughput point Output count rates of 65.3 and 17.8 kcps were obtained with filter rise time of 1.0 and 3.2 μs, respectively, at an input count rate of 270 kcps. This algorithm can be easily adapted to other double-exponential decaying scintillators by changing the decay times used in the energy reconstruction formula. [ABSTRACT FROM AUTHOR]

We analyzed temperature-induced changes of variant surface antigen (vsAg) expression in Paramecium primaurelia, using immuno-techniques and mRNA determinations. Upon a 23 degrees C to 33 degrees C shift, the old vsAg, type 156G, remains on the cell surface for a time, when already mRNA for the new form, 156D, is expressed. A considerable amount of 156D-specific mRNA is formed 45-48 h after the temperature shift, while 156D surface expression reaches maximal levels only after >72 h. A new aspect of these experiments is that, during this transition, the old vsAg is steadily released in high-molecular-weight form into the culture medium, as found by dot blot and Western blot analysis of concentrated culture medium. The new vsAg form is first inserted into the somatic cell membrane, before it spreads also into cilia. In the reverse transition, 33 degrees C to 23 degrees C, the adaptation on the level of transcription and surface expression is considerably faster. While we had previously shown, under steady-state conditions (constant temperature), the occurrence of a degradation pathway by endocytotic and phagocytotic ingestion of vsAg this may proceed in parallel to the steady release of old vsAg from the cell surface into the medium. Altogether these combined processes may facilitate the installation of the new vsAg type. [ABSTRACT FROM AUTHOR]

Abstract: While position-sensitive photomultiplier tubes (PSPMTs), coupled to fast scintillators, are widely used as photon detectors in applications such as medical imaging systems (PET, gamma camera, etc.), where it is desirable to combine good time resolution with the capability of locating the point of photon interaction, their count rate limitations (of order of tens of thousands of cps) have precluded their use in more demanding applications. Recently, in a neutron imaging application, we found that, by using custom designed fast anode and dynode readout circuits, coupled to a fast digital pulse processing board, we could operate a PSPMT at rates approaching 1 million cps while retaining good position resolution, linearity and time resolution. These developments therefore significantly extend the range of PSPMT application. [Copyright &y& Elsevier]

We present a new approach to charged-particle spectroscopy of short-lived nuclei produced by relativistic projectile fragmentation. The system based on digital DGF-4C CAMAC modules and newly developed fast-reset preamplifiers was tested at the Fragment Separator of GSI. We were able to detect low-energy (≈1 MeV) decay signals occurring a few microseconds after a heavy-ion implantation accompanied by a release of ≈1 GeV energy. Applications for the study of one- and two-proton radioactivity are discussed. [Copyright &y& Elsevier]