A simple method for formation of CdS nanoparticles on the surface of carbon nanotubes (CNTs) aligned perpendicularly to the silicon substrate has been developed. The size and shape of the CdS nanoparticles were found to depend on the temperature of a solution containing CdCl(2), (NH(2))(2)CS, and NH(3) and the deposition time. Electron microscopy study revealed a direct contact between CdS nanoparticles and CNT surface. X-Ray photoelectron spectroscopy examination of the CdS/CNT hybrid material detected surface oxidation of the grown nanoparticles.

Although salinity is one of the major problems limiting agricultural production around the world, the underlying mechanisms of high NaCl perception and tolerance are still poorly understood. The eects of dierent bathing solutions and fusicoccin (FC), a known activator of plasma membrane ATPase, on plasma membrane potential (E m ) and net¯uxes of Na , K and H were studied in wheat suspension cells (Triticum aestivum) in response to dierent NaCl treatments. E m of cells in Murashige and Skoog (MS) medium was less negative than in cells exposed to a medium containing 10 mM KCl 0 . 1 mM CaCl 2 (KSM) and to a basic salt medium (BSM), containing 1 mM KCl and 0 . 1 mM CaCl 2 . Multiphasic Na accumulation in cells was observed, peaking at 13 min after addition of 120 mM NaCl to MS medium. This time scale was in good agreement with net Na ¯u x changes measured non-invasively by moving ion-selective microelectrodes (the MIFE system). When 120 mM NaCl was added to all media studied, a quick rise of Na in¯ux was reversed within the ®rst 20 min. In both 120 and 20 mM NaCl treatments in MS medium, net Na eux was observed, indicating that active Na transporters function in the plant cell response to salt stress. Lower external K concentrations (KSM and BSM) and FC pre-treatment caused shifts in Na ¯u xes towards net in¯ux at 120 mM NaCl stress.# 2000 Annals of Botany Company

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The effects of fusicoccin (FC) on the early growth processes in sorghum ( Sorghum vulgare M.) seeds germinated in water and in 0.1 M or 0.2 M NaCl solutions were investigated. We studied the rate of seed imbibition, the onset of radicle protrusion, the occurrence of the first mitoses, the mitotic index, the distribution of cells according to the phases of the cell cycle, as well as the length and weight of roots. Seed imbibition was considerably accelerated by treating them with 5 × 10 -6 M FC for 1 h. In these FC-treated seeds placed on NaCl solutions, FC stimulated water influx into seeds, radicle protrusion, and occurrence of the first mitoses. FC pretreatment did not affect substantially the distribution of meristematic cells according to the periods of the cell cycle after 72 h of seed germination on water or 0.1 M NaCl. Root growth was inhibited by 0.1 M NaCl, but it was partially recovered in the presence of FC. 0.2 M NaCl caused a decrease in the mitotic index and in the number of cells in the S phase, an accumulation of cells in the G 2 period and in the prophase, as well as a considerable inhibition of root growth. FC pretreatment of seeds subsequently germinated on 0.2 M NaCl resulted in an increase in the number of cells in the G 1 period, in the mitotic index, and in the root-growth rate. FC virtually did not affect the growth of sorghum in the absence of salt. Pretreatment of seeds with FC followed by salinization resulted in an increase in the water content in seeds. It is suggested that a FC-induced increase in the water content of seeds accelerated metabolic processes in seeds germinating on NaCl solutions, thus regulating ionic homeostasis and thereby stimulating the initial growth processes.

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A method for synthesis of a hybrid material from CdS nanoparticles and carbon nanotubes (CNT) by the precipitation of CdS nanoparticles on the CNT surface from an aqueous solution containing the Cd II salt, thiourea, and ammonia was developed. The dependences of the size of particles formed on the CNT on the temperature of the solution and the duration of precipita tion were observed. The degree of imperfection of the CNT surface exerts a substantial effect on the density of the precipitated CdS particles.The development and use of nanoparticles of semicon ductors is of interest for the preparation of photoabsorbing and photoemitting cells. The range of absorption and lu minescence frequencies depends on the nanoparticle size. Hybrid nanosystems combining the properties of one di mensional carbon nanotubes (CNT) and quantum dots of semiconducting materials are being actively developed presently. It is expected that the interaction of semicon ducting nanoparticles with light would result in the elec tron photocurrent through the nanotube and localization of the hole on the nanoparticle. This would allow one to desigh new types of photogalvanic devices. 1 Recently it was repeatedly reported the precipitation of various types of nanoparticles of metal sulfides and selenides, such as CdSe (see Ref.2), Cu 2 S (see Ref.3), and CdS (see Refs 4-6) on the CNT. In particular, modified CdS nano particles were pre prepared and then precipitated from solution on the CNT surface, which made it possible to use such systems as biosensors. 7 During the electrochemical precipitation of CdS nanoparticles ∼15 nm in diameter on bamboo like nanotubes 100 nm in diameter, the CNT were pre oxidized with nitric acid for better precipitation. 8 The photoconductivity of the hybrid CdS/CNT materials was enhanced. The precipitation of CdSe nanoparticles on bundles of double wall CNT was described. 9 The CNT were pre fluorinated to provide a more uniform distribu tion of nanoparticles on the surface. A more complicated multistep approach to the formation of CdS nanoparticles on the nanotube surface is known. 6 By oxidizing the CNT surface with a mixture of acids the surface was firstly func tionalized with carboxyl groups and then Cd 2+ ions were "cross linked" to these groups. As a result of the interac tion with Na 2 S, CdS nanoparticles ∼8 nm in size were formed on the CNT surface.Hydrogen sulfide is often used for the synthesis of CdS. Hydrogen sulfide should be replaced by less toxic organic sulfur containing compounds capable of acting as a sup plier of sulfur atoms. One of the most available sulfur containing reagents of this type is thiourea (NH 2 ) 2 CS (Thio). For example, CdS films were obtained 10,11 from aqueous solutions containing Thio, Cd II salts, ammonia, and NaOH. A possibility to prepare CdS nanoparticles by this reaction was described. 12 The purpose of the present work is to study the forma tion of CdS nanoparticles on the surface of an array of multiwalled CNT aligned perpendicularly to the silicon support using the thio...

Twelve cultivars of barley ( Hordeum vulgare L.) from the collection of the Vavilov Institute of Plant Industry, Russian Academy of Agricultural Sciences, were screened by assessing the length of 6-day-old seedlings grown in water culture at 70, 120, and 170 mM NaCl. As a result, two salt-susceptible cultivars, Belogorskii and QB 60.1, and three salt-tolerant cultivars, Elo, Odesskii 115, and Local from Ecuador, were selected, and these cultivars were used in the greenhouse soil-culture experiments. The grain yield of salt-tolerant cultivars was affected by NaCl to a lesser degree than that of the salt-susceptible cultivars. In both cases, soil salinization increased the sodium content in the seedlings as compared to the control plants. Characteristically, saltsusceptible cultivars accumulated more Na + in their shoots than salt-tolerant cultivars; the reciprocal pattern was found in the roots. Soil salinization decreased K + content in the shoots of the salt-susceptible cv. Belogorskii as compared to the control, whereas in the most tolerant cv. Local from Ecuador, the potassium content increased.