Effect of soil texture on the emission characteristics of porous clay pipe for subsurface irrigation

Laboratory and numerical experiments were carried out to analyze the effect of soil texture on the emission characteristics of porous clay pipe used for subsurface irrigation. Results show that the emission rate of the pipe is linearly related to the applied hydraulic head in the open environment. With the pipe embedded in the soil, the emission rate becomes a function of the soil texture and the applied hydraulic head. For a given soil texture, as the applied hydraulic head in the pipe increases, the moisture content in the vicinity of the pipe becomes higher, and the effect of the capillary forces on the emission rate of the pipe decreases. Under saturated conditions in the vicinity of the pipe, the effect of capillary forces in the flow domain on the emission rate of the pipe is negligible. The study results are useful in designing the lateral spacing and installation depth of the pipelines, irrigation run time and length, and the hydraulic head required for proper operation of porous clay pipe based subsurface irrigation systems.     

Comparing invasive and non-invasive of isolated Shigella flexneri by electron microscopy of cell culture, SDS-PAGE and Congo red method

BACKGROUND: The aim of this study was to compare invasive and non-invasive strains of Shigella flexneri isolated from Tehran by a 120 kDa protein band by SDS-PAGE, electron microscopy of cell culture and Congo red dye methods. METHODS: S. flexneri strains were isolated by standard bacterial methods from fecal specimens of children attending to the 3 children's hospitals. Phenotype analysis for screening virulent of strains of S. flexneri was done on a plate of tryptic soy agar contained 0.003% Congo red dye. Whole membrane protein preparations were used to examine the protein profiles of the inner and outer membrane of these Gram-negative bacteria. The protein mixture was electrophoresed through a polyacrylamide gel. The gel was stained with Coomassie brilliant blue R250 and destained with ethanol and acetic acid. HeLa cell culture was done by two-step preparations: one for light microscopy and the other for electron microscopy. RESULTS: Some of S. flexneri (46%) were Congo red positive colonies. S. flexneri with negative Congo red phenotype could not enter the HeLa cell culture. A 120 kDa protein band was found in 46% of these bacteria which could enter into HeLa cell culture. Pseudopod structures which facilitate bacterial cell-to-cell spread were readily identified by electron microscopy. DISCUSSION: Since the existence of 120-kDa protein band was corresponded to enter of S. flexneri into the HeLa cell culture and correlated with Congo red dye positive, for identification of invasive and non-invasive S. flexneri strains, the use of a 120-kDa protein band by SDS-PAGE or a simple, rapid and very cheap Congo red dye method is recommended. Because, there are some deaths due to Shigella sp. in our country, notification on the isolation of these bacteria in both children hospitals laboratories and private clinical laboratories is important.     

Managing crop damage caused by house mice (Mus domesticus) in Australia

A large-scale outbreak of the house mouse populations occurs in grain growing in Australia on average once every four years. High densities of mice cause major yield losses to cereal crops, and low to moderate densities of mice also cause some losses. Several predictive models based on rainfall patterns have been developed to forecast mouse density. These models carry some uncertainty and the economic value of basing management actions on these models is not clear. Baiting is the most commonly used method and zinc phosphide and other rodenticide bait are effective in reducing up to 90% of mouse populations. Ecologically-based best farming practice for controlling mice has recently been developed on the basis of long-term field studies of mouse populations. No effective biological control method has been developed for mice. However, grain growers still cannot make economically rational decisions to implement control because they do not know the pest threshold density (D_T) above which the economic benefits of control exceed the economic costs of control. Applied predator-prey theory suggests that understanding the relationship between mouse density and damage is the basis for determining D_T. Understanding this relationship is the first research priority for managing mouse damage. The other research priority is to develop a reliable method to estimate unbiased mouse density.     

Comparison of population estimators and indices for monitoring house mice in sorghum crops

House mice (Mus musculus domesticus Schwarz & Schwarz, 1943) are monitored in Australia and China to track changes in mouse population densities and forecast their potential damage to cereal crops. The present study compared population indices based on the number of different mice caught and overall trap success from live-trapping with an oil card index (OC) and a tracking index (T) for monitoring mice in sorghum crops immediately before crop maturation. T was measured as the percentage of track board covered with mouse footprints night⁻¹, and OC as the percentage of card removed by mice night⁻¹. The reliability of these abundance indices was quantified by Pearson correlation coefficient with the trappable population size (Ñ), which was estimated by capture–recapture over eight consecutive nights on 175 × 5 trapping grids, in sorghum crops on two properties on the Darling Downs, Queensland. Because of differences among individual mice in capture probability, Model M_h of program MARK was used to account for such heterogeneity and to estimate the size of each mouse population. The number of individual animals caught was more strongly correlated with Ñ than trap success and, therefore, might be a more reliable index; the data suggest that three trapping occasions provide optimal precision for this index. T correlated significantly with Ñ only at sites where the canopy of sorghum plants was closed, and its use should, therefore, be restricted to this habitat. OC did not correlate with Ñ because none or very little of the cards was eaten at low to moderate mouse densities. T and the number of animals caught over three trapping nights are recommended for monitoring mice in sorghum crops immediately prior to crop maturation.     

Impact of integrated management of nitrogen fertilizers on yield and nutritional quality of potato

Abstract

The aim of this study was to investigate the influence of different compositions of nitrogen (N) sources on yield and nutritional quality in potato cultivars (Solanum tuberosum L.). The experiment used a factorial arrangement as two factors in randomized complete block design. Factor (A) was nitrogen sources: control, 75% M?+?25%V, 50% M?+?50%V, 100% M, where M plots received nitrogen from mineral fertilizer and V plots received nitrogen from vermicompost. Factor (B) was potato cultivars (Sante and Savalan). In Sante cultivar, 75% M?+?25%V produced the highest total and marketable yield. In Savalan, cultivar application of vermicompost in 75% M?+?25%V and 50% M?+?50%V increased significantly total and marketable yield as compared with 100% M. Application of vermicompost significantly decreases tuber nitrate content and increases nitrogen-use efficiency. In Savalan, cultivar 50% V?+?50%M and in Sante cultivar 75% V?+?25%M can effectively be used for improving yield and nutritional quality of tuber.     

Development and characterization of MWNTs/Chitosan biocomposite fiber

The Preparation of conductive biocomposite fiber through Carbon nanotubes (CNTs) incorporation into biopolymer matrixes has stimulated much interest for bio-implant applications. The present study focuses on development and characterization of biocomposite fiber composed of chitosan (CHT) as a biopolymer and multiwall carbon nanotubes (MWNTs) as a conductive filler. In term of processing, the most important challenge is to prepare a highly stable dispersion of MWNTs in biopolymer matrix. The hydrodynamic diameter distribution of CNTs in acetic acid solution acquired by dynamic light scattering (DLS).Results demonstrate the supreme stability of CNTs dispersion which is extremely essential for homogenous distribution of CNT in polymeric matrix. Rheological properties of the spinning solution have also been investigated to adjust the viscosity for fiber processing step. A range of viscosity between 2000–8000 cP, has been recorded in different CNT loading. The scanning electron microscopy (SEM) images of the surface and cross sectional area of the fibers reveal the formation of nano-pores after MWNT addition. The tensile strength show a maximum increase of about 33.65 % compared to bare CHT. Also, the measurement of four probe electrical conductivity for different MWNTs loading shows a maximum conductivity of 0.107 S/cm at percolation threshold of 2.89 wt%.     

Improved immunogenicity of Newcastle disease virus inactivated vaccine following DNA vaccination using Newcastle disease virus hemagglutinin-neuraminidase and fusion protein genes

The present study describes the development of DNA vaccines using the hemagglutinin-neuraminidase (HN) and fusion (F) genes from AF2240 Newcastle disease virus strain, namely pIRES/HN, pIRES/F and pIRES-F/HN. Transient expression analysis of the constructs in Vero cells revealed the successful expression of gene inserts in vitro. Moreover, in vivo experiments showed that single vaccination with the constructed plasmid DNA (pDNA) followed by a boost with inactivated vaccine induced a significant difference in enzyme-linked immunosorbent assay antibody levels (p < 0.05) elicited by either pIRES/F, pIRES/F+ pIRES/HN or pIRES-F/HN at one week after the booster in specific pathogen free chickens when compared with the inactivated vaccine alone. Taken together, these results indicated that recombinant pDNA could be used to increase the efficacy of the inactivated vaccine immunization procedure.