Response of Different Genotypes of Faba Bean Plant to Drought Stress

Drought stress is one of the major abiotic stresses that are a threat to crop production worldwide. Drought stress impairs the plants growth and yield. Therefore, the aim of the present experiment was to select the tolerant genotype/s on the basis of moprpho-physiological and biochemical characteristics of 10 Vicia faba genotypes (Zafar 1, Zafar 2, Shebam, Makamora, Espan, Giza Blanka, Giza 3, C4, C5 and G853) under drought stress. We studied the effect of different levels of drought stress i.e., (i) normal irrigation (ii) mild stress (iii) moderate stress, and (iv) severe stress on plant height (PH) plant⁻¹, fresh weight (FW) and dry weight (DW) plant⁻¹, area leaf⁻¹, leaf relative water content (RWC), proline (Pro) content, total chlorophyll (Total Chl) content, electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H₂O₂) content, and activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) of genotypes of faba bean. Drought stress reduced all growth parameters and Total Chl content of all genotypes. However, the deteriorating effect of drought stress on the growth performance of genotypes “C5” and “Zafar 1” were relatively low due to its better antioxidant enzymes activities (CAT, POD and SOD), and accumulation of Pro and Total Chl, and leaf RWC. In the study, genotype “C5” and “Zafar 1” were found to be relatively tolerant to drought stress and genotypes “G853” and “C4” were sensitive to drought stress.     

Rheological and thermal stability of novel weak gels based on sulfonated polyacrylamide/scleroglucan/chromium triacetate

The present study deals with weak gels based on sulfonated polyacrylamide (SPA)/scleroglucan (SC)/Cr³⁺ with an exceptional thermal stability in electrolyte media. The rheological results showed that on increasing the SC concentration the shear viscosity and storage modulus of the SPA/SC/Cr³⁺ system were increased and the dependence of the storage modulus on frequency became weaker. The yield stress of the SPA/SC/Cr³⁺ system was higher than that of the corresponding SPA/SC system. The thermochemical stability increased with increasing relaxation time. The SPA/SC/Cr³⁺ semi‐interpenetrating network exhibited the lowest viscosity loss in electrolyte media; therefore this system may be a potential candidate for enhanced oil recovery applications. © 2016 Society of Chemical Industry     

Nanoencapsulation of montmorillonite clay within poly(ethylene glycol) nanobeads by electrospraying

The present study describes the preparation and characterization of a novel nanocomposite, based on montmorillonite clay (MMT) encapsulation in poly(ethylene glycol) (PEG) by an electrospraying process. PEG/MMT nanocomposites with MMT contents ranging from 1 to 5 wt % were successfully prepared and characterized in relation to their morphological, spectroscopic, structural, and thermal properties. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy micrographs showed that the PEG nanobeads formed spherical shapes, and with increasing amount of MMT clay, the size of the beads decreased significantly, ranging from 120 to 3.7 nm. The Fourier transform infrared spectroscopy results suggested that there was no significant chemical interaction between PEG and MMT clay. However, the d‐spacing of MMT clay in PEG/MMT increased, a clear indication of the intercalation of PEG in the interlayer spaces of MMT clay. Furthermore, the thermal stability of PEG polymer decreased upon encapsulation of MMT clay in PEG/MMT composites. Nanoindentation results showed that the hardness and Young's modulus of the PEG/MMT composites increased with 3 wt % loading of MMT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45048.     

Reinforcement of electroactive characteristics in polyvinylidene fluoride electrospun nanofibers by intercalation of multi-walled carbon nanotubes

This research work reports on development and characterization of multi-walled carbon nanotube (MWCNT)-doped polyvinylidene difluoride (PVDF) nanofibers by the electrospinning method. PVDF is an extensively studied polymer both theoretically and experimentally due to its appealing ferroelectric, piezoelectric, and pyroelectric properties which strongly favors its promising applications in the development of micro/nanostructure devices. The foremost reason for its ferroelectric and piezoelectric behaviors has been attributed to its crystalline structure, specifically the presence of β-phase; however, the existence of the small percentage of β-phase in pristine PVDF limits its applications. To enhance the electroactive features in the PVDF, MWCNTs have been doped in it to prepare electrospun nanofibers, as electrospinning is a single-step approach. These nonwoven nanofibers were prepared at a DC voltage of 20 kV which were subsequently calcined at 100 °C for 12 h. The estimation of crystal structure and phase identification in these nanofibers have been determined by attenuated FT-IR and XRD, while the morphology, microstructure, mean diameter, and length have been examined by FE-SEM. The observed electrical conductivity, capacitance, permittivity (ε), conductivity (δ), and impedance (Z) in these samples have been tailored by doping a range of MWCNT contents and optimizing the experimental conditions.     

Effects of Cyclic Loading,Freeze-Thaw and Temperature Changes on Shear Bond Strengths of Different Concrete Repair Systems

An experimental study was performed to evaluate the residual shear bond strengths between different cementitious and resinous repair materials and substrate concrete after being subjected to cyclic loading, freeze-thaw, and temperature changes. In this paper, techniques and results of test methods that induce shear along the repair/concrete interface are discussed. In addition to the effect of surface preparation on the strength of the old concrete surface, which proved the saw cut surface as the most suitable substrate concrete for shear bond strength assessment, by means of cylindrical shear and friction-transfer methods, the effects of cyclic loading, freeze-thaw, and temperature changes on the shear bond strengths of six different repair systems are illustrated. Analysis of the results indicated that: in order to avoid fatigue failure, the maximum safe stress level to be applied should be between 20 to 40% of the original shear bond strength of the repair system, and the critical stress level differs for different repair materials; 300 freeze-thaw cycles can reduce the shear bond strength of a resin mortar by up to about 80%; and 200 cycles, of temperature changes can reduce the original shear bond strength of a cementitious mortar by up to about 90%.     

HYDROMAGNETIC UNSTEADY RIVLIN-ERICKSEN THIRD-GRADE FLOW FOR STOKES' SECOND PROBLEM

In this article, the flow of an unsteady third-grade Rivlin-Ericksen fluid on an oscillating plate is discussed. The magnetic lines of force act perpendicular to the flow field. Several interesting features of the flow are obtained. The physical interpretation of the second-grade parameters, third-grade parameters, oscillating frequency, and magnetohydrodynamic parameters are examined graphically and then are deduced to already known results in the literature.     

Electrochemical effects of silane pretreatments containing cerium nitrate on cathodic disbonding properties of epoxy coated steel

In the recent years, silane materials, because of their environmental friendly nature and ease of application have been attended as an alternative for chromate conversion coatings. Different materials were searched for improvement of the efficiency of silane formulation. In this research, pretreatment of carbon steel substrates was carried out using γ-glycidoxypropyl-trimethoxysilane (γ-GPS) as functionalized silane. Cerium nitrate as a corrosion inhibitor material was introduced into the silane material and epoxy resin was applied on the pretreated steel substrates. Effects of the pretreatment on electrochemical properties, cathodic disbondment, dry and wet adhesion strength, and surface morphology of resultant epoxy coating were investigated. Results showed that pretreatment of steel substrate with γ-glycidoxypropyl-trimethoxysilane (γ-GPS) doped with cerium nitrate leads to improvement of cathodic disbondment and also dry and wet adhesion of epoxy coating. Furthermore, this type of pretreatment reduced the disruption of interfacial bonds at the binder/substrate interface. Addition of 2?wt% cerium nitrate into the silane formulation led to the maximum efficiency of resultant coating.     

Design of a dual function buried channel waveguide for pulse compression and dispersion compensation in two different wavelengths for the purpose of optical integration

Silicon - Optical pulse compression and dispersion compensation are two important applications in optical systems. The present paper proposes a dual function buried channel waveguide to be used in...     

Synthesis and characterization of novel curcumin based polyurethanes varying diisocyanates structure

In this research work, novel polyurethanes (PUs) based on blends of curcumin/1,4-butane diol (BDO) by varying the structure of diisocyanates were prepared following step growth polymerization. Structural study of blends and various diisocyanates based PU through Fourier Transform Infrared (FTIR) spectroscopy confirmed the incorporation of curcumin into the backbone of the PU. The scanning electron microscopic (SEM) study confirmed the well dispersion of incorporated curcumin and homogeneity of surface of synthesized samples. The SEM results also indicated that surface morphology of synthesized samples much dependent on diisocynates structure. Moreover SEM images inferred that phase separation is more pronounced in aromatic diisocyanate based PU. The anti-bacterial and anti-fungal tests were performed against different strains in order to determine the biocompatibility of the curcumin based PU. The antimicrobial activity results revealed that the material having aromatic diisocyanate are more biocompatible than the aliphatic diisocyanates in the PU structure. On the whole, this work is actually a step towards the generation of novel biocompatible materials preferably useful for biomedical applications.     

Deformation behavior of isotactic polypropylene crystallized via a mesophase

The mechanical behavior of semicrystalline isotactic polypropylene (iPP) of different crystallinity, crystal morphology and superstructure was investigated by standard tensile stress–strain analysis, dynamic-mechanical analysis, and in situ observation of the deformation by atomic force microscopy (AFM). Emphasis is put on the comparison of the mechanical characteristics of specimens containing either non-isometric lamellae, being arranged in spherulites, or nodular isometric domains, which are not organized in a superstructure. The formation of lamellae/spherulites and of nodules was controlled by the conditions of crystallization. The replacement of cross-hatched monoclinic lamellae and a spherulitic superstructure by randomly arranged isometric nodules leads to a distinct increase of the ductility and toughness, even if the crystallinity is identical. The modulus of elasticity and the yield stress increase as expected with increasing crystallinity. Slightly lower values of Young’s modulus and yield strength are detected if samples contained non-lamellar crystals in a non-spherulitic superstructure, proving an effect of the crystal shape on the deformation behavior. For the first time, tensile deformation of semicrystalline iPP which contains nodular ordered domains instead of lamellae has been followed by in situ AFM.