The effect of survey density on the results of geopedological approach in soil mapping: A case study in the Borujen region, Central Iran

Landscapes are considered to be complex systems that are hierarchically structured and spatially scale-dependent. Geopedology allows a systematic approach in geomorphic analysis for soil mapping that extrapolates the results obtained at sample areas up to similar units. This paper examines the influence of sampling intervals on the accuracy of geopedological results in the Borujen region, Central Iran. After a primary interpretation of the study area on air photos (1:20 000), a geomorphic unit that encompassed the maximum surface of the sample area (and also the study area) was selected and was surveyed at three different scales: 500, 250 and 125 m intervals. The credibility of generalization of the results of the geopedological approach for the studied unit was tested by comparison with three profiles in a similar unit outside the sample area, named the validation area. Although the type of mapping unit in the sample area and the validation area was the same (complex) at the three different scales, the dominant soil in the validation area was different in comparison with the sample area at 125 and 250 m intervals. The results indicate that the geopedological approach to soil mapping is better carried out in reconnaissance or exploratory surveys. Comparison of soil types between the unit in the sample area and the validation area at three scales indicated that by increasing the taxonomic accuracy, the hidden aspects of the soils may be more identifiable. Therefore, although the geopedological approach tries to distinguish more homogeneous soil mapping units, it still is not able to fully define and represent the variability and apparent chaotic nature of the soils. We recommend further investigations on different techniques of stratifying the landscape in order to better analyze and understand the soil forming processes and soil variability and to improve sampling and mapping approaches.     

Laser induced surface modification of clay-PAN composite nanofibers

In this study a newly laser treatment method for surface modification of nanofibers is introduced. The new method is based on different infrared absorption of materials. Surface modification of Clay-PAN composite nanofibers was performed using selective laser etching approach with CO₂ pulsed laser in order to increase surface area of nanofibers. The surface structure of resulted nanofibers is characterized using field emission scanning electron microscope and the results show characteristic modification of the surface topography of laser treated nanofibers. The modified surface structure of nanofibers was studied and analyzed for different laser pulse numbers and laser fluence. The results show that nanofiber surface modification strongly depends on the number of CO₂ laser pulses and frequency of modified sites on the surface of nanofibers increasing with increasing the pulse fluence. This new technique is highly selective and can also compete with conventional techniques for nanofibers surface modification.     

Remobilization of Phosphorus in Tea Plants

Tea [Camellia sinensis (L.) O. Kuntze] is a highly phosphorus (P) deficiency-tolerant species, however, involving mechanisms have not been investigated so far. In this work, mechanisms for intrinsic efficiency of P utilization were studied in tea seedlings grown hydroponically without or with adequate P supply. The contribution of P reserve in cotyledons to the P nutrition of tea seedlings and the role of mature leaves were examined at two contrasting P supply levels in plants with intact or severed cotyledons. During three subsequent harvest intervals, distinct reduction of P content was observed not only in cotyledons, but also in the mature leaves, stem and roots of plants supplied with low P. In plants supplied adequately with P, in contrast, a continuous rise of P content was detected. It was concluded that the cotyledons of tea plants are a major source of P but not organic compounds for growth of the young seedlings.     

Mass Transfer and Color Changes Kinetics of Infrared-Vacuum Drying of Grapefruit Slices

ABSTRACT

The effects of combined infrared-vacuum drying parameters, including infrared power (300–400 W), pressure (5–25 kPa) and time (0–140 min) on the drying kinetics of grapefruit slices were investigated. Both the infrared lamp power and vacuum pressure influenced the drying time of grapefruit slices. The regression results showed that the quadratic model satisfactorily described the drying behavior with highest R and lowest SE values. The effective moisture diffusivity increases as power increases and range between 5.83 × 10^–10 and 2.13 × 10^–9 m²/s. The color scale parameters, including redness (a*), yellowness (b*) and lightness (L*) values of dried grapefruit slices increased during drying. The rise in infrared power has a negative effect on the color change intensity (?E) and with increasing in infrared radiation power it was increased. Different kinetic models were used to fit the experimental data and the results revealed that the power model was the most suitable to describe the ?E.     

Prevalence and characterization of multidrug resistance and variant Salmonella genomic island 1 in Salmonella isolates from cattle,poultry and humans in Iran

Salmonella enterica is a common food‐borne pathogen with occasional multidrug resistance (MDR). Salmonella genomic island (SGI1) is a horizontally transmissible genomic island, containing an MDR gene cluster. All Salmonella serotypes are public health concern, although there is an additional concern associated with those that harbour SGI1. In Iran, there are no data on the presence of SGI1 variants in Salmonella isolates. The present study was conducted to identify MDR‐ and SGI1‐carrying Salmonella strains isolated from various sources and to compare their genetic relatedness between human and animal sources. In total, 242 Salmonella isolates collected from chicken, cattle, and humans from 2008 through 2014 were studied. The isolates were tested for resistance to 14 antimicrobials via the disc diffusion method. They were also tested for the presence of SGI1 variants via PCR, and genetic relatedness was evaluated based on pulsed‐field gel electrophoresis (PFGE). Resistance to at least one antimicrobial agent was observed in 132 (54%) Salmonella isolates (n = 242), while more than 40% of the isolates showed MDR. Based on PCR analysis, eight variants of SGI1, including SGI1, SGI1‐B, SGI1‐C, SGI1‐D, SGI1‐F, SGI1‐I, SGI1‐J and SGI1‐O, were found in both human and animal isolates. Statistical analysis revealed no significant difference in the prevalence of SGI1 variants between human and animal isolates (p > 0.05). Macrorestriction PFGE analysis of the isolates with the same SGI1 variant and resistance patterns revealed genetic relatedness ranging from 70% to 100% among human and animal isolates. According to our review, this is the first documentation of SGI1 in Salmonella isolates in Iran. The presence of similar SGI1 variants in both humans and animals, along with their related PFGE patterns, suggests that food‐producing animals may be a source of MDR Salmonella isolates in Iran.     

Synthesis and characterization of novel biocompatible four-arm star-shaped copolymers by using a new tetramethacrylate core

The objective of this study was to synthesize and characterize two novel four-arm star-shaped copolymers of N-isopropylacrylamide (NIPAAm), methacrylic acid (MAA), N,N-(dimethylamino) ethyl methacrylate (DMAEMA) and 1-vinyl-2-pyrrolidone (VP) that was initiated from a new tetramethacrylate monomer (TMAM) as the core by the free radical polymerization approach. Novel multiacrylic monomer was synthesized via three key consecutive reactions. All the intermediates and the final product have been fully characterized. The polymerization reaction was conducted by the core first method and the star-shaped copolymers were analyzed by FT-IR, ¹H NMR and Thermo-Gravimetric Analysis (TGA). MTT assay was used to evaluate in vitro cytotoxicity of the star copolymers on lung cancer cell lines. These star copolymers showed no in vitro cytotoxicity to A549 cells. The results showed that these copolymers can be promising drug carriers because they showed no in vitro cytotoxicity and they have various functional groups for association and interaction with drugs.     

Assessing geopedological soil mapping approach by statistical and geostatistical methods: A case study in the Borujen region,Central Iran

Geopedology, using geomorphologic and supervised classification bases, has been proposed as a soil surveying method. It undertakes a systematic approach to map soilscapes. This approach tries to reduce the budget of accomplishing soil surveys as well as increasing the purity of mapping units. But to what extent it has been succeeded is the question. The main objective of this research was to validate the geopedological mapping methodology by statistical and geostatistical methods in the Borujen region, Central Iran. After a primary interpretation of the study area on air photos (1:20 000 scale), 94 pedons were excavated on a 125 m square sampling grid in the sample area for geostatistical studies. To achieve the statistical aims, a geomorphic unit which encompassed the maximum surface of the sample area (and also the study area) was selected and the biggest delineation of this unit with 19 pedons was considered. The credibility of generalizing the results of the geopedological approach for the studied unit was tested by comparison with 15 pedons in a similar unit outside the sample area, named the validation area. Properties of the soils, including percentage of clay, rock fragments (2–75 mm) and total carbonates in the soil family control section, percentage of organic matter in the A horizon and its thickness, were selected for statistical and geostatistical analyses. Univariate and multivariate statistical analyses obtained from the units in the sample and the validation areas, showed that the means of soil variables were similar. A high difference between A horizon thickness variances in the sample area and the validation area affected the significance of the variation test in the univariate and multivariate results. Our study demonstrated that, when comparing the same factors from sample and validation areas, the spatial distribution and spatial dependency level of soil attributes were different. Therefore, although the geopedological approach tries to distinguish more homogeneous soil mapping units, it is still not able to fully define and represent the real variability of soil properties and show the chaotic behavior or nature of the soils. We recommend further investigations on different techniques of stratifying the landscape in order to better analyze and understand the soil-forming processes and the nature of soil variability and to improve sampling and mapping approaches. We suggest that the additional determination of the phases of landforms and phases of soil series will improve mapping in the future.     

Establishing an efficient in vitro propagation system for sweet cherry rootstocks Gisela 12 and Maxma 14 and assessment of genetic homogeneity by ISSR markers

Journal of Crop Science and Biotechnology - This survey is aimed at the assessment of the possible effect of different plant growth regulators (PGRs) on the micropropagation of commercial sweet...     

Two-stage sequential sampling: A neighborhood-free adaptive sampling procedure

Designing an efficient sampling scheme for a rare and clustered population is a challenging area of research. Adaptive cluster sampling, which has been shown to be viable for such a population, is based on sampling a neighborhood of units around a unit that meets a specified condition. However, the edge units produced by sampling neighborhoods have proven to limit the efficiency and applicability of adaptive cluster sampling. We propose a sampling design that is adaptive in the sense that the final sample depends on observed values, but it avoids the use of neighborhoods and the sampling of edge units. Unbiased estimators of population total and its variance are derived using Murthy’s estimator. The modified two-stage sampling design is easy to implement and can be applied to a wider range of populations than adaptive cluster sampling. We evaluate the proposed sampling design by simulating sampling of two real biological populations and an artificial population for which the variable of interest took the value either 0 or 1 (e.g., indicating presence and absence of a rare event). We show that the proposed sampling design is more efficient than conventional sampling in nearly all cases. The approach used to derive estimators (Murthy’s estimator) opens the door for unbiased estimators to be found for similar sequential sampling designs.