Electrodeposition of homogeneous and adherent polypyrrole/Na<Superscript>+</Superscript>-cloisite nanocomposite on iron electrodes

In this work homogeneous and adherent nanocomposite of polypyrrole (PPY) with Na⁺-Cloisite nanoclays was successfully prepared by insitu electropolymerization of pyrrole monomer in the presence of Na⁺-Cloisite nanoclays. Formation of nanocomposite and incorporation of nanoclays in polypyrrole matrix was endorsed and characterized by FTIR spectroscopy studies, X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM). The X-ray difraction patterns showed that PPY was intercalated between clay layers in the order of nanoscale. The morphology of the resulted nanocomposite was studied by scanning electron micrograph (SEM). Cyclic voltammetry experiments were carried out in different electrolytes and showed that nanocomposite is electroactive, while conductivity of the nanocomposite derived from four point probe technique indicated that the resulted nanocomposite is conductive. The anticorrosive properties of a thin layer coating of PPY/Na⁺-Cloisite nanocomposite on iron coupons was evaluated and compared with pure polypyrrole coating. According to the results in various corrosive environments PPY/Na⁺-Cloisite nanocomposite has enhanced corrosion protection effect in comparison to pure polypyrrole coating. It was observed that the corrosion protection effect was due to the dispersion of nanoclays in polymer matrix, which results in the increase in the corrosion potential and decrease in corrosion current and corrosion rate.     

The effect of inorganic nitrogen on the added nitrogen interaction of soils in incubation experiments

A laboratory incubation experiment was conducted to study the effect of indigenous inorganic N on the immobilization of applied N and on the occurrence of an added N interaction (ANI). Samples of six Mollisols from Illinois were incubated with ¹⁵N-labelled (NH₄)₂SO₄ (100 or 200 mg N kg^-1 soil), with or without the use of 0.01 M CaCl₂ to extract inorganic N (mainly NO _inf3 ^sup- ) before incubation. From 6 to 49% of the N applied was immobilized, higher percentages being obtained with unextracted soils than with the extracted soils and with the higher rate of N addition. Net mineralization of native N occurred in both the unextracted and extracted soils, but was more extensive in the unextracted soil and increased with the addition of N. The increases were accompanied by a positive ANI, which usually exceeded the amount of applied N immobilized and increased with the rate of addition. The ANI values observed with extracted soils were attributed to increased mineralization of native organic N.     

Relative significance of soil and nitrogenous fertilizer in nitrogen nutrition and growth of wetland rice (Oryza sativa L.)

Summary A pot experiment was conducted to compare the yields from five commercially cultivated varieties (Bas-198, Bas-370, Bas-Pak, Bas-385, and IR-6) of rice (Oryza sativa L.) and to establish the relative significance of soil N and fertilizer N (¹⁵N-labelled ammonium sulphate) in affecting crop performance. Another aim was to study the interaction of fertilizer N and soil N as influenced by different rice varieties. Among the five varieties tested, Bas-Pak gave the maximum dry matter and N yield. The N-use efficiency (percentage of applied N taken up by the plants) of different varieties ranged between 33.7 and 43.7%, Bas-Pak being the most efficient. Significant losses of fertilizer N occurred from the soil-plant system. The maximum N loss (52.1% of applied N) was observed with IR-6 and the minimum loss (39.2%) with Bas-Pak. A substantial increase in the uptake of soil N following the application of fertilizer and an interaction between the two N sources were observed with all varieties except Bas-385. The interaction was attributed to greater root proliferation following the application of fertilizer. It was concluded that a varietey with greater potential to use soil N is likely to give a better yield and that, of the two N sources, the availability of soil N was more important in determining the yield performance of different varieties of rice.     

Availability of soil and fertilizer nitrogen to wheat (Triticum aestivum L.) following rice-straw amendment

Summary A pot experiment was conducted to study the N availability to wheat and the loss of ¹⁵N-labelled fertilizer N as affected by the rate of rice-straw applied. The availability of soil N was also studied. The straw was incorporated in the soil 2 or 4 weeks before a sowing of wheat and allowed to decompose at a moisture content of 60% or 200% of the water-holding capacity. The wheat plants were harvested at maturity and the roots, straw, and grains were analysed for total N and ¹⁵N. The soil was analysed for total N and ¹⁵N after the harvest to determine the recovery of fertilizer N in the soil-plant system and assess its loss. The dry matter and N yields of wheat were significantly retarded in the soil amended with rice straw. The availability of soil N to wheat was significantly reduced due to the straw application, particularly at high moisture levels during pre-incubation, and was assumed to cause a reduction in the dry matter and N yields of wheat. A significant correlation (r=0.89) was observed between the uptake of soil N and the dry matter yield of wheat with different treatments. In unamended soil 31.44% of the fertilizer N was taken up by the wheat plants while 41.08% of fertilizer N was lost. The plant recovery of fertilizer N from the amended soil averaged 30.78% and the losses averaged 45.55%     

Changes in peroxidase and phenols activity in apple fruit inoculated with antagonistic Pseudomonas fluorescens isolates and Botrytis mali

The biocontrol activity of three isolates of Pseudomonas fluorescens against gray mold of apple fruit caused by Botrytis mali and their ability to induce biochemical defense response in apple tissue were investigated. Apple fruit (Malus domestica) wounds were inoculated with 20 microL bacterial suspension (10(8) CFU mL(-1)) of Pseudomonas fluorescens followed 24 h later by 20 microL of conidial suspension of B. mali (10(5) conidia mL(-1)). The apples were then incubated at 20 degrees C for 11 days. Lesion diameters were evaluated 6 and 10 days after pathogen inoculation. In addition to controlling gray mold, these three isolates of P. fluorescens caused increase in peroxidase activities that reached maximum levels 2-6 days after pathogen inoculation. Phenolic accumulation was increased in apple fruit treated with antagonists and inoculated with B. mali and exhibited the highest level 6-8 days after treatment. The ability of P. fluorescens to increase activities of peroxidase and levels of phenol compounds maybe one of mechanism responsible its biocontrol activity.     

Cancer regression in patients after transfer of genetically engineered lymphocytes

Through the adoptive transfer of lymphocytes after host immunodepletion, it is possible to mediate objective cancer regression in human patients with metastatic melanoma. However, the generation of tumor-specific T cells in this mode of immunotherapy is often limiting. Here we report the ability to specifically confer tumor recognition by autologous lymphocytes from peripheral blood by using a retrovirus that encodes a T cell receptor. Adoptive transfer of these transduced cells in 15 patients resulted in durable engraftment at levels exceeding 10% of peripheral blood lymphocytes for at least 2 months after the infusion. We observed high sustained levels of circulating, engineered cells at 1 year after infusion in two patients who both demonstrated objective regression of metastatic melanoma lesions. This study suggests the therapeutic potential of genetically engineered cells for the biologic therapy of cancer.     

Comparative Study of DOP and CND Methods for Leaf Nutritional ‎Diagnosis of Vitis Vinifera in Iran

In this study, the norms for Vitis Vinifera have been derived and compared using the Compositional Nutrient Diagnosis (CND) and Deviation from Optimum Percentage (DOP) diagnose methods to determine the nutrient deficiency in Vineyards at Central Alborz region, Iran. A total of 200 leaf samples were collected during two years from Vitis Vinifera trees and nutrient concentrations of Mn, Zn, Fe, Mg, Ca, K, P, N, B, and Cu were measured. The results showed that there are differences between DOP and CND diagnosis methods. According to mean DOP indices for nutrient elements, the priority of the deficiency of elements was as follows: Mn > P > Ca > Fe > Cu. In addition, the CND standard norms were determined as F^c_i(V_N) = 32.34, F^c_i(V_P) = 34.49, F^c_i(V_K) = 48.58, F^c_i(V_Ca) = 54.39, F^c_i(V_Mg) = 64.11, F^c_i(V_Mn) = 19.71, F^c_i(V_Zn) = 47.64, F^c_i(V_Fe) = 53.32, F^c_i(V_Cu) = 32.44, F^c_i(V_B) = 41.59, and F^c_i(R_d) = 39.19 ton.ha^?1. The results also showed that there is the deficiency of manganese, nitrogen, iron, and phosphorus in vineyards. Therefore, the field observations due to the implications of apparent deficiencies of nutrient elements in the gardens of the region are more consistent with the DOP method.     

Comparison of two versions of the acetylene inhibition/soil core method for measuring denitrification loss from an irrigated wheat field

 Two versions of the acetylene inhibition (AI)/soil core method were compared for the measurement of denitrification loss from an irrigated wheat field receiving urea-N at a rate of 100 kg ha^–1. With AI/soil core method A, the denitrification rate was measured by analysing the headspace N₂O, followed by estimation of N₂O dissolved in the solution phase using Bunsen absorption coefficients. With AI/soil core method B, N₂O entrapped in the soil was measured in addition to that released from soil cores into the headspace of incubation vessels. In addition, the two methods were also compared for measurement of the soil respiration rate. Of the total N₂O produced, 6–77% (average 40%) remained entrapped in the soil, whereas for CO₂, the corresponding figures ranged from 12–65% (average 44%). The amount of the entrapped N₂O was significantly correlated with the water-filled pore space (WFPS) and with the N₂O concentration in the headspace, whereas CO₂ entrapment was dependent on the headspace CO₂ concentration but not on the WFPS. Due to the entrapment of N₂O and CO₂ in soil, the denitrification rate on several (18 of the 41) sampling dates, and soil respiration rate on almost all (27 of the 30) sampling dates were significantly higher with method B compared to method A. Averaged across sampling dates, the denitrification rate measured with method B (0.30 kg N ha^–1 day^–1) was twice the rate measured with method A, whereas the soil respiration rate measured with method B (34.9 kg C ha^–1 day^–1) was 1.6 times the rate measured with method A. Results of this study suggest that the N₂O and CO₂ entrapped in soil should also be measured to ensure the recovery of the gaseous products of denitrification by the soil core method. Received: 12 May 1998     

Genotype-Dependent Differential Responses of Three Forage Species to Calcium Supplement in Saline Conditions

Salt toxicity comprises of osmotic and ionic components both of which can severely affect root and shoot growth. In many crop species, supplemental calcium (Ca) reduces the inhibition of growth typical of exposure to salt stress. The objective of this study was to compare whole plant growth and physiological responses to interactive effect of salinity and Ca level on three forage species [African millet (AM), tall wheat grass (TW), and perennial ryegrass (PR)] differing in tolerance to sodium chloride (NaCl) salinity. Plants were grown under glasshouse condition and supplied with nutrient solution containing 0, 100, and 250 mM NaCl supplemented with 0.5, 5, or 10 mM calcium chloride (CaCl₂). Plant growth, ionic concentration, water relations, and solute (proline and glycinebetaine) concentrations of the plants were determined two weeks after the salinity treatments. At 100 mM NaCl, there was a moderate reduction in dry matter (DM) production of all three species. A drastic decrease in DM occurred at 250 mM NaCl. Supplemental Ca reduced the adverse effects of salinity on all three species. The TW showed higher shoot and root growth in 100 and 250 mM NaCl than AM and PR. It also showed the highest DM at 5 and 10 mM Ca supplement. The shoot and root DM of TW increased by about 45 and 15%, respectively compared to the control. Chemical analysis indicated that in TW, Ca restricted both uptake and transport of sodium (Na) from root to shoot. It also increased Ca and potassium (K) concentrations in both organs. The transport of K and Ca from root to shoot of AM and PR were decreased by NaCl, but were restored with increasing Ca in the medium. The opposite occurred for Na. In PR, more K uptake was observed in shoot at 250 mM NaCl with 10 mM Ca supplement. The sap osmotic potential (Ψ_S) was the highest in TW at 10 mM Ca in the presence of 250 mM NaCl. Contribution of various solutes to the difference in Ψ_S among the species from the control and 250 mM salt treatment differed greatly. Supplemental Ca induced decline in the leaf Ψ_S of TW which was predominately due to K, glycinebetaine, Na and proline accumulation. Addition of 10 mM Ca to the growth medium maintained a low Na and a high K level. Accumulation of glycinebetaine and proline in leaf contributed the NaCl tolerance of TW. The presented results suggest that supplement Ca, not only improved ionic relations but also induced plant ability in production of compatible solutes (glycinebetaine and proline) and osmotic adjustment. Accordingly, genotype dependent capacity could be found using supplemental Ca.