The influence of graphene reinforced electrospun nano-interlayers on quasi-static indentation behavior of fiber-reinforced epoxy composites

The aim of this research is to investigate the development and evaluation of hybrid multi-scale aramid/epoxy composites interleaved with electrospun graphene nanoplatelets/nylon 66 (GNPs/PA66) mats. The reinforced nanofiber mats were explored for their best mechanical properties and PA66 nanofibers with 1 wt% GNPs were selected for composite production. Quasi-static indentation tests were performed on both pristine and nanofiber-modified composites. The experimental results revealed that the introduction of reinforced interleaves within the interlaminar interfaces of composites promotes fracture toughness compared to pristine interleaves. It is shown that there is a particular interleaf thickness for optimum toughening effect of nanofibers. The optimum thicknesses for pristine and reinforced interleaves are 35 and 17.5 μm, respectively.     

Effects of carbohydrate source and polyethylene glycol on maturation and germination of somatic embryos in walnut (<Emphasis Type="Italic">Juglans regia</Emphasis> L.)

Low efficiency of somatic embryo maturation, germination, and conversion to plantlets is a major problem in many species including J. regia L. Germination efficiency of somatic embryos is very low in walnut. In this study, effects of two carbohydrate sources, sucrose and maltose (each at 3% and 6%), and two kinds of PEG (4000 and 6000) (each at four levels of 1.5%, 3%, 5% and 7.5%) on maturation and germination of walnut embryos were tested. The number of somatic embryos increased conspicuously on medium containing PEG. Furthermore, higher levels of PEG-4000 (7.5%) could remarkably enhance the morphogenesis of somatic embryos and the number of embryos produced. PEG-4000 stimulated somatic embryo maturation of walnut. This stimulatory effect was dependent on the carbohydrate source used. Sucrose in combination with PEG-4000 produced 50% of cotyledonary and normal somatic embryos. Different concentrations of PEG were effective on the number of embryos with a shoot meristem. PEG-4000 7.5% and sucrose 3.0% produced the highest rate (50.0%) of normal shooting embryos. However, PEG (4000, 6000) and maltose caused an unfavorable effect and increased the frequency of abnormal shaped somatic embryos.     

Using arbuscular mycorrhiza to reduce the stressful effects of soil compaction on corn (Zea mays L.) growth

Soil compaction is of great importance in agriculture, because its high levels may adversely affect plant growth and the environment. Since mechanical methods are not very efficient and economical, using biological methods to alleviate the stress of soil compaction on plant growth may be beneficial. The objectives of this study were to: (1) evaluate the effects of soil compaction on corn (Zea mays L.) growth, and (2) test the hypothesis that applying arbuscular mycorrhiza (AM) with different origins can partially or completely overcome the stressful effects of soil compaction on corn growth under unsterilized and sterilized conditions. Corn was planted in unsterilized and sterilized compacted soils, while treated with three species of AM including, Iranian Glomus mosseae, Iranian Glomus etunicatum, and Canadian Glomus mosseae, received from GINCO (Glomales in vitro Collection), Canada. Plant growth variables and soil resistance parameters were determined. AM significantly increased root fresh (maximum of 94% increase) and dry (maximum of 100% increase) weights in the compacted soil. AM with different origins may improve corn growth in compacted soils, though its effectiveness is related to the level of compaction and also to the interaction with other soil microorganisms.     

Evaluation of furrow fertigation and model validation on maize field

In new agricultural practices, joint application of water and fertilizer has been become common. Uniform distribution of fertilizer in soil and in plant growth duration is possible by this procedure. The main objective of this study was to investigate furrow fertigation management effects on distribution uniformity and runoff losses of nitrate in a cornfield, and validate a numerical fertigation model. A field experiment was carried out with seed corn at 12 experiments with a complete randomized block design during 2 years. Nitrogen requirement was determined by soil analysis and accomplished in four stages of the growth: before cultivation, in seven leaves, shooting and earring stages which first section (before cultivation) was applied by manual distribution and others by fertigation. Potash and super phosphate fertilizers (based on soil analysis) were sprayed on soil before planting. Water requirement was estimated by using class a evaporation pan multiplied by plant (Kc) and pan coefficients. Nitrogen fertilizer was solved in irrigation water and injected at the last minutes of irrigation. The results showed that fertilizer distribution uniformity of the low quarter (DU_LQ) ranged from 85.7% to 91.5% in first year, and 69.9% to 95.5% in second year. While water DU_LQ ranged from 74.1 to 98.2% in 2 years. Nitrate losses of surface runoff have ranged between 5.7 and 42.0% in first year according to the application time and the outflow flux. In second year, the nitrate losses decreased by adopting appropriate management based on the experiences of first year. The fertigation model was subsequently applied to the experimental data and results showed good agreement with field data.     

Microsporidia in household dogs and cats in Iran; a zoonotic concern

Microsporidia in dogs and cats is primarily caused by the obligate, intracellular parasite Encephalitozoon cuniculi, which is a member of the phylum Microsporidia. The aim of the current study is the detection of this parasite in stool samples of small animals of Iran, by polymerase chain reaction. Microsporidia spp. was found in 31% (31/100) of dogs (E. cuniculi (18/100), Encephalitozoon bieneusi (8/100) and Encephalitozoon intestinalis (5/100)), and 7.5% (3/40) of the specimens obtained from cats were infected with E. bieneusi. Sequencing of PCR products confirmed these results. In conclusion, Microsporidia infection seems to be fairly common in pet animals of Iran, especially in dogs. This finding could indicate the importance of pet animals as zoonotic reservoirs of microsporidial human infections.     

Antibiotic Supplements Affect Electrophysiological Properties and Excitability of Rat Hippocampal Pyramidal Neurons in Primary Culture

Introduction: Antibiotic supplements are regularly used in neuronal culture media to control contamination; however, they can interfere with the neuronal excitability and affect electrophysiological properties. Therefore, in this study, the effect of penicillin/streptomycin supplements on the spontaneous electrophysiological activity of hippocampal pyramidal neurons was examined. Methods: Electrophysiological whole-cell patch-clamp recordings from rat hippocampal pyramidal cells in primary culture were performed to investigate the effects of antibiotic supplements on the intrinsic excitability of cultured cells. Results: The present findings indicated that presence of antibiotic supplements (penicillin/streptomycin) in the culture medium altered the intrinsic electrical activity of hippocampal pyramidal neurons in primary culture. These alterations included: 1) depolarized resting membrane potential; 2) a significant enhancement in the after-hyperpolarization amplitude; 3) a significant increase in the area under the action potential and in the decay and rise time of the action potential; 4) a significant broadening of action potential and 5) a significant reduction in the firing frequency. Conclusion: These findings suggest that addition of antibiotic supplements to culture media influences the neuronal excitability and alters the electrophysiological properties of cultured neurons, possibly through changing the ionic conductance underlying neuronal excitability. Key Words: Primary cell culture, Patch-clamp techniques, Hippocampus