The relationship between fluidized bed electrostatics and entrainment

Existing methods of predicting entrainment from gas-fluidized beds, based exclusively on hydrodynamic variables and mechanisms, show extremely wide discrepancies in their predictions and often deviate by many orders of magnitude from experimental values. Based on simultaneous measurement of electrostatic charges in the freeboard region and entrainment, this paper will show that inter-particle electrostatic forces on relatively fine particles can be at least of the same order of magnitude as the gravity forces that must be overcome for entrainment to take place. Moreover, incorporation of a term for inter-particle electrostatic force leads to substantial improvement in the ability to correlate our experimental entrainment data. These results show that it is essential to consider electrostatic forces when predicting entrainment from gas-fluidized beds

Quantitative comparison of ammonia and 3-indoleacetic acid production in halophilic, alkalophilic and haloalkalophilic bacterial isolates in soil

In order to measure the concentration of ammonia production via corrected Nesslerization method and 3-indoleacetic acid as Salkowski method in halophilic, alkalophilic and haloalkalophilic bacterial isolates, soil samples were collected from six different areas of Khorasan Razavi and bacterial isolates isolated and purified using different growth medium accordingly. The alkalophiles isolates showed maximum ammonia production (0.055%) among the three groups of bacteria which this amount was 9.5 times of its average in haloalkalophiles isolates (0.0058%) and 13 times of ammonia production average in halophiles (0.004%). Mean comparison of the concentration3-indoleacetic acid production in three groups also showed that the most isolates of halophiles, alkalophiles and haloalkalophiles were IAA producer with 0.0003, 0.0001 and 0.0021percent respectively that the IAA amount in haloalkalophilic group was about 6 and 14.5 times of it in halophilic and alkalophilic isolates respectively. Equations to predict the concentration of ammonia and 3-indole acetic acid production was only significant in the haloalkalophilic isolates for ammonia production (P=0.046) and halophilic isolates for IAA production (P=0.015) under effect of electrical conductivity and pH in 0.05 probability level. Results represented that the multiple regression analysis for prediction of ammonia and IAA concentrations producing by isolates had not any significant performance in high and low concentrations under effect of electrical conductivity and pH. It seems that the uses of the two sensitive measuring methods (Nesslerization and Salkowski) after some modifications show promises and are recommend able in research due to their ease of implementation and relatively accurate results.Keywords: Alkalophiles; haloalkalophiles; halophiles; 3-indoleacetic acid; nesslerization method; salkowski method

Impact of Silicon Foliar Application on the Growth and Physiological Traits of Carthamus tinctorius L. Exposed to Salt Stress

Althought safflower is a tolerant crop against many environmental stresses, but its yield and performance reduce under stress. The aim of this experiment was to investigate the effect of silicon (Si) application on the possibility of increasing salinity resistance and related mechanisms in safflower. A greenhouse experiment was conducted to investigate the effects of Si spraying (0, 1.5 and 2.5 mM) on safflower plants grown under salt stress condition (non-saline and 10 dS m−1). Salinity reduced seedling emergence percent and rate, growth parameters and disrupted ion uptake but increased emergence time and specifc leaf weight. Spraying of Si increased plant height, fresh and dry weight, leaf area, relative water content (RWC), potassium, calcium and silicon content, while sodium absorption was decreased. As a result, the K+/Na+ and Ca2+/Na+ ratios were increased. Elevated ion contents and ratios indicate an enhanced selectivity of ion uptake following silicon application and may increase ion discrimination against Na+. Treatment with 2.5 mM Si showed the most positive effect on the measured growth traits. Decrement in leaf area ratio under salinity indicates a more severe effect of salinity on leaf area compared to biomass production. On the other hand, silicon reduced the specific leaf weight under stress and non-stress conditions, which revalues the positive effects of silicon on leaf area expansion. Improvement of RWC may a reason for the icrease in leaf area and biomass production. Data shows that spraying with Si especialy with 2.5 mM can reduce salinity stress damage to safflower and increase biomass production

Analysis of indigenous zinc in alkaline sodic soil solutions by graphite furnace atomic absorption spectrometry

Analytical determination of ultra low levels of micronutrients in soil solutions is one of the major problems limiting trace element studies in alkaline sodic soils. The low concentrations of trace metals in environmental samples are often measured by the graphite furnace atomic absorption spectrometry (GFAAS) technique. However, considerable difficulty was found with zinc (Zn) determination in alkaline sodic soil solutions. The effects of various chemical modifiers (phosphoric acid, ammonium phosphate, nitric acid, and palladium (Pd)] on GFAAS determination of ultra trace levels of Zn in soil solutions of four alkaline sodic soils were investigated in this study. The concentration of Zn in the soil solution was significantly (P<0.01) higher in the presence of modifiers relative to that determined in the absence of modifiers. In addition, coefficient of variance [(CV) 21.5%] in the absence of chemical modifiers was up to three times higher than those determined with chemical modifiers (7 to 10.2%). Chemical modifiers also decreased the characteristic concentration (increased sensitivity). The decrease ranged from 22.1 to 34.6% for Pd and phosphoric acid, respectively, compared to that in the absence of chemical modifiers. The maximum ashing temperature for standard Zn solution increased from 300°C in the absence of modifiers to 800°C with phosphoric acid and ammonium phosphate, indicating increased stability of Zn at high temperatures. Based on the recovery test data, characteristic concentration, atomization temperature, and the shape of atomic signal peak, analysis of Zn in the presence of phosphoric acid was recommended for soil solution Zn

Effect of laser priming on canola yield and its components under salt stress

The effect of laser priming at different irradiation times on canola yield and its components under saline conditions were investigated. The results showed that laser priming had a positive effect on yield and its components and caused yield increase under saline conditions. Increase in salt levels had a negative and significant effect on seed yield, number of seeds per pod, number of pod per plant, pod length and plant height. The results showed that 45-min laser priming had the strongest effect on yield and yield components and reduced significantly the adverse effects of salinity.By contrast, laser radiation applied for 60 and 75 min, resulted in a dramatic decrease in yield and its components. Correlation coefficients between the attributes showed that canola yield had a positive and significant correlation with plant height, number of seeds, pod per main branch and lateral branches, length of pod and number of lateral branches. Effects of laser and salinity were significant on lateral branch pod length but not on main branch pods

The Study Efficiency of Reduced Rate of Pendimethalin Integrated with Mulch and Hand-Weeding in Fennel (Foeniculum vulgare Mill.).

Introduction: Fennel has been cultivated as a medicinal and spice plant for a long time in different areas of Iran. However, its characterizes such as slow-growing, weak establishment, owning low LAI index and long seasonal plant, make it a poor competitor against weed, therefore, protection from weed is essential for successful cropping. The combination of management practices, such as mulching with herbicide could improve weed control efficacy of reduced rates. Limited information is available on control of weeds in fennel as important medicinal plant. Using a combination of physical control and herbicides at reduced rate may increase the efficacy of both treatments while reducing the cost of the weed control program and environmental impact of over reliance on herbicide applications. Therefore, the objective of this study was to evaluate the effects of reduced rates of the pendimethalin alone and in combination with wheat straw mulch and one hand-weeding on the growth of weed and grain yield of cultivated fennel. Materials and Methods: this experiment was carried out at the Research Farm of Faculty of Agriculture, University of Zanjan in the spring 2012 to introduce an integrated weed control method in fennel. In this experiment the efficacy of different rates of pendimethalin alone and with combination with one hand weeding and straw mulch for selective control of grass and broadleaf weed species were evaluated. Field experiment was laid out as factorial based on randomized complete block design with three replications. Factors were application dose (0, 660, 990 and 1320 g a.i. ha-1) and supplemental weed control (none, one hand-weeding, mulching). A plot with whole season hand weeding was also included as control. The recommended doses of pendimethalin were 1320 g ai ha-1. Fennel was planted at 10 seeds m-2, at 0.5 m row spacing, on May 6, 2012. Pendimethalin was applied pre-emergence soon after planting. In the mulch treatments, wheat straw were spread evenly after fennel planting at the rate of 2 kg m-2. In the weed control treatments which one hand weeding used as supplemental physical control, a hand-weeding was performed at 50 days after planting. At fennel maturity, weeds were harvested from a 0.5 m2 area and dried in an oven for 48 h at 75 oC and biomass was recorded. For assessing the effect of the treatments on fennel seed yield a 2 m2 centre area of the plots was harvested manually. Data were subjected to an analysis of variance using PROC GLM in SAS Software. The means were compared using a Fisher's Protected Least Significance Difference test (P< 0.05). Results and Discussion: Biomass of broad leaf weeds was significantly affected by herbicide doses and supplemental control. However, application dose and supplemental control interaction were not significant on broad leaf weeds biomass. Maximum broadleaf weed biomass control (85.9%) was recorded by recommended dose of pendimethalin. For a given dose of herbicide, weed control efficiency was higher when the physical methods were used as supplemental control and generally one hand-weeding was effective than mulching. All weed management treatments reduced biomass of grass weeds compared to weedy control. No differences were observed between the grass weed biomass in plots which received 75% and 100% of the labeled recommended rate of pendimethalin. Significant differences (p < 0.05) among herbicide rates and 50% of the labeled recommended rate (660 g a.i. ha-1) was observed for grass weed biomass. Biomass of grass weeds was also significantly affected by physical control. Maximum grass weed control (86%) was observed with one hand-weeding than the mulch. Same to broadleaf, the interaction effect of application dose × supplemental control treatments was not significant for grass weeds biomass. Total weeds biomass was significantly affected by herbicide. The interaction effect of application dose × supplemental control treatments were significant for total weeds biomass. Maximum weed biomass (1837.5 g.m-2) was recorded in weedy control. When herbicide combined with one hand-weeding, the rate of 660 g a.i. ha-1 of pendimethalin was sufficient to provide 81% total weed control, which was statistically similar to the best control achieved for all dose and physical combination treatments. Fennel seed yield and yield component was significantly affected by application dose and physical control. The greatest seed yield loss (97.6%) was recorded in no weed control plots. and the lowest seed yield loss (13%) was seen in the recommended dose of pendimethalin + one hand-weeding plot. When one hand-weeding was used as a supplemental control, increased herbicide application rates from 990 to 1320 g a.i. ha-1 did not significantly influence the level of fennel seed yield. Conclusions Overall, results of this study showed that pendimethalin in labeled recommended rate and applied alone was not sufficient to provide season long weed control. The recommended dose in combination with one hand weeding could not prevent of economic yield loss. As a result, it is recommended to test efficient herbicide or other methods of weed management of this plant. To improve the level of weed control with mulch, application of herbicides at the same time as the mulch or supplemental hand-weeding could be suggested as a part of integrated weed management in fennel

Combined effects of polyacrylamide and nanomagnetite amendment on soil and water quality, Khorasan Razavi, Iran

Nanotechnology is increasingly being used to remediate polluted soil and water. However, few studies are available assessing the potential of nanoparticles to bind surface particles, decrease erosion, and minimize the loading of water pollutants from agricultural surface discharge. To investigate this potential, we treated in situ field plots with two practical surface application levels of anionic polyacrylamide (PAM only) with and without nanomagnetite (PAM-NM), examined soil physical properties, and evaluated the impact of this amendment on contaminant sorption and soil erosion control. Polyacrylamide and PAM-NM treatments resulted in 32.2 and 151.9 fold reductions in Mn2+, 1.8 and 2.7 fold for PO43--P, and 2.3 and 1.6 fold for NH4+-N, respectively, compared to the control. Thus, we found that the combination of PAM and NM, had an important inhibitory effect on NH4+-N and PO43--P transport from soil-pollutants which can contribute substantially to the eutrophication of surface water bodies. Additionally, since the treatment, especially at a high concentration of NM, was effective at reducing Mn2+ concentrations in the runoff water, the combination of PAM and NM may be important for mitigating potential risks associated with Mn2+ toxicity. Average sediment contents in the runoff monitored during the rainfall simulation were reduced by 3.6 and 4.2 fold for the low and high concentration PAM-NM treatments when compared to a control. This treatment was only slightly less effective than the PAM-only applications (4.9 and 5.9 fold, respectively). We report similar findings for turbidity of the runoff (2.6-3.3 fold for PAM only and 1.8-2.3 fold for PAM-NM) which was caused by the effects of both PAM and NM on the binding of surface particles corresponding to an increase in aggregate size and stability. Findings from this field-based study show that PAM-modified NM adsorbents can be used to both inhibit erosion and control contaminant transport