Influence of clay nanoparticles on the physical and rheological characteristics of short term aged asphalt binder

This research paper presents laboratory investigation on the physical and rheological properties of asphalt binder modified with Organic Montmorillonite Nanoclay (OMMT). Two different concentrations (1% and 7% by weight of base asphalt) of OMMT was selected toblendwith80/100 penetration grade asphalt binder. The base as well as the OMMT modified asphalt binders was subjected to short term aging process by means of Rolling Thin Film Oven test (RTFO) in order to investigate the influence of the addition of OMMT nano clay in the asphalt binder properties after aging. Bituminous binder properties were investigated by both physical and rheological methods .In general, the physical test results demonstrated prominent increment in softening point; viscosity and decrement in penetration for both concentration of OMMT modified binder as compared to non-modified binder. The results of the experiments indicated that the addition of nano particles was helpful in increasing the complex modulus values and in improving rutting resistance of the RTFO binder. The phase angle of the binders generally decreased with an increase in nano content and RTFO aging procedure. Also, the results indicated that modified binders show better rheological properties compared to standard bitumen. The addition of OMMT to base asphalt binder has led to noticeable improvements in aging resistance this may be due to the homogeneous dispersion of nano particles consisting of layer silicate in the asphalt medium. Thus, nano clay is foreseen as a novel kind of resistance to aging and permanent deformation potential for bitumen

Effect of short term aging on organic montmorillonite nanoclay modified asphalt

In order to increase the life of bituminous pavement, quality of bitumen needs to be enhanced and modified. The objective of this study was to evaluate the conventional and rheological properties of binders containing various percentages of organic montmorillonite nanoclay particles before and after a short-term aging process. Two types of organic montmorillonite nanoclay (N3 and N4) were chosen to blend with 80/100 base asphalt in various concentrations (3%, 7% and 9%) by weight of the asphalt and subjected to aging using the Rolling Thin Film Oven in order to simulate short term aging. The conventional properties of organic montmorillonite nanoclay modified bituminous binders before and after aging were characterized using retained penetration, increment in softening point, and viscosity aging index concepts while the rheological properties were characterized in terms of their complex shear modulus, phase angle, overall resistance to deformation, and their viscoelastic behavior were measured at higher temperatures ranging from 40 to 82°C using Dynamic Shear Rheometer. The test results showed that the introducing of organic montmorillonite nanoclay to the asphalt binder improves the aging effect on the conventional and fundamental properties as compared to unaged modified asphalt. This improvement can recognized through the higher retained penetration and lower increment in softening point as well as viscosity aging index. Also, the result showed remarkable improvement in rutting resistance of the aged modified binder which results in better resistance to permanent deformation at intermediate and high temperature. Compared between the two types of nanoclay, N3 showed better enhancement to the conventional and rheological properties of asphalt binders and exhibited greater resistance to rutting before and after aging process, which can be contributed to the better dispersion of clay layers of N3 inside asphalt binder that refer to the types of surface treatment of the montmorillonite nanoclay

Effect of organic montmorillonite nanoclay concentration on the physical and rheological properties of asphalt binder

This study explores the effect of the addition of various concentration of organic nanoclay on the physical and rheological properties of asphalt binder. Two types (N3 and N4) of Organic Montmorillonite Nanoclay (OMMT) were used and blended with 80/100 penetration grade asphalt in various concentrations (0%, 3%, 5%, and 9%) by weight of bitumen. The physical properties of unaged base and nanoclay modified asphalt were characterized using viscosity, softening point, and penetration tests. The rheological properties of unmodified and nanoclay modified asphalt were determined using Dynamic Shear Rheometer (DSR) in accordance with AASHTO T315 in order to evaluate the effectiveness of OMMT type and concentration on the physical and rheological properties of asphalt binder. The results indicated remarkable increment in softening point; viscosity and decrement in asphalt binder's penetration for both types and contents of organic nanoclay as compared with unmodified bitumen. By increasing the amount of nanoclay content, the DSR results showed tremendous improvement on the rheological properties of nanoclay modified asphalt such as Complex Shear Modulus G* and Phase Angle δ at medium and high temperatures. As a consequence, the results showed that the organic nanoclay modified asphalts had higher rutting resistance and lower dissipated energy per load cycle this may contributed to the dispersion of the silicate platelet in bitumen that reinforce the binder. In comparison, N3 showed better effect in improving physical and rheological properties of asphalt binders and rutting resistance than N4, which may contributed to the homogenously dispersion of nanoclay particles that led to form an exfoliated structure in OMMT modified asphalt. The two-way ANOVA statistical analysis was carried out which indicated that OMMT concentration was more significant than OMMT type on rutting parameter, viscosity at high and intermediate temperature, and softening point while nanoclay type was more significant on penetration

Bifurcation analysis of rotating axially compressed imperfect nano-rod

Static stability problem for axially compressed rotating nano-rod clamped at one and free at the other end is analyzed by the use of bifurcation theory. It is obtained that the pitchfork bifurcation may be either super- or sub-critical. Considering the imperfections in rod's shape and loading, it is proved that they constitute the two-parameter universal unfolding of the problem. Numerical analysis also revealed that for non-locality parameters having higher value than the critical one interaction curves have two branches, so that for a single critical value of angular velocity there exist two critical values of horizontal force

Identification of Candidate Genes and Genomic Regions Associated with Adult Plant Resistance to Stripe Rust in Spring Wheat

Wheat stripe rust (caused by Puccinia striiformis f. sp. tritici) is a major disease that damages wheat plants and affects wheat yield all over the world. In recent years, stripe rust became a major problem that affects wheat yield in Egypt. New races appeared and caused breakdowns in the resistant genotypes. To improve resistance in the Egyptian genotypes, new sources of resistance are urgently needed. In the recent research, a set of 95 wheat genotypes collected from 19 countries, including Egypt, were evaluated for their resistance against the Egyptian race(s) of stripe rust under field conditions in the two growing seasons 2018/2019 and 2019/2020. A high genetic variation was found among the tested genotypes. Single marker analysis was conducted using a subset of 71 genotypes and 424 diversity array technology (DArT) markers, well distributed across the genome. Out of the tested markers, 13 stable markers were identified that were significantly associated with resistance in both years (p-value ≤ 0.05). By using the sequence of the DArT markers, the chromosomal position of the significant DArT markers was detected, and nearby gene models were identified. Two markers on chromosomes 5A and 5B were found to be located within gene models functionally annotated with disease resistance in plants. These two markers could be used in markerassisted selection for stripe rust resistance under Egyptian conditions. Two German genotypes were carrying the targeted allele of all the significant DArT markers associated with stripe rust resistance and could be used to improve resistance under Egyptian conditions

Effect of mineral filler type and particle size on asphalt-filler mastic and stone mastic asphalt laboratory measured properties

This study examines four types of industrial and by-product wastes filler, namely; limestone as reference filler, ceramic waste, coal fly ash, and steel slag. One filler content consists of 10% by total weight of aggregate with three proportions; 100% passing 75micron (μm), 50/50 % passing 75μm/20μm, and100% passing 20μm was used. Laboratory tests were performed to determine the impact of different filler types and filler particle size on some properties of asphalt-filler mastics and Stone Mastic Asphalt mixture (SMA). The results indicate that the application of industrial and byproducts wastes as filler improves the properties of asphalt-filler mastic and SMA mixtures. The increased stiffness, due to addition of the filler, is represented by an increase in softening point, in viscosity, stability and resilient modulus as well as a decrease in penetration. The optimum asphalt content at given filler to asphalt ratio increased with the decrease in filler particle size regardless filler type. It was also determined that the filler type and particle size has significant effect on the mixture property. Among these three proportions, the samples prepared with the filler size proportion of 100% passing the 75microm gave the best value in terms of Marshall Quotient, the filler size proportion of 50/50 gave the best value in terms of Resilient Modulus while Stability vary depends on filler type

Highly efficient intracellular transduction in three-dimensional gradients for programming cell fate

Fundamental behaviour such as cell fate, growth and death are mediated through the control of key genetic transcriptional regulators. These regulators are activated or repressed by the integration of multiple signalling molecules in spatio-temporal gradients. Engineering these gradients is complex but considered key in controlling tissue formation in regenerative medicine approaches. Direct programming of cells using exogenously delivered transcription factors can by-pass growth factor complexity but there is still a requirement to deliver such activity spatio-temporally. We previously developed a technology termed GAG-binding enhanced transduction (GET) to efficiently deliver a variety of cargoes intracellularly using GAG-binding domains to promote cell targeting, and cell penetrating peptides (CPPs) to allow cell entry. Herein we demonstrate that GET can be used in a three dimensional (3D) hydrogel matrix to produce gradients of intracellular transduction of mammalian cells. Using a compartmentalised diffusion model with a source-gel-sink (So-G-Si) assembly, we created gradients of reporter proteins (mRFP1-tagged) and a transcription factor (TF, myogenic master regulator MyoD) and showed that GET can be used to deliver molecules into cells spatio-temporally by monitoring intracellular transduction and gene expression programming as a function of location and time. The ability to spatio-temporally control the intracellular delivery of functional proteins will allow the establishment of gradients of cell programming in hydrogels and approaches to direct cellular behaviour for many regenerative medicine applications

Genetic Diversity and Population Structure of F3:6 Nebraska Winter Wheat Genotypes Using Genotyping-By-Sequencing

The availability of information on the genetic diversity and population structure in wheat (Triticum aestivum L.) breeding lines will help wheat breeders to better use their genetic resources and manage genetic variation in their breeding program. The recent advances in sequencing technology provide the opportunity to identify tens or hundreds of thousands of single nucleotide polymorphism (SNPs) in large genome species (e.g., wheat). These SNPs can be utilized for understanding genetic diversity and performing genome wide association studies (GWAS) for complex traits. In this study, the genetic diversity and population structure were investigated in a set of 230 genotypes (F3:6) derived from various crosses as a prerequisite for GWAS and genomic selection. Genotyping-by-sequencing provided 25,566 high-quality SNPs. The polymorphism information content (PIC) across chromosomes ranged from 0.09 to 0.37 with an average of 0.23. The distribution of SNPs markers on the 21 chromosomes ranged from 319 on chromosome 3D to 2,370 on chromosome 3B. The analysis of population structure revealed three subpopulations (G1, G2, and G3). Analysis of molecular variance identified 8% variance among and 92% within subpopulations. Of the three subpopulations, G2 had the highest level of genetic diversity based on three genetic diversity indices: Shannon’s information index (I) = 0.494, diversity index (h) = 0.328 and unbiased diversity index (uh) = 0.331, while G3 had lowest level of genetic diversity (I = 0.348, h = 0.226 and uh = 0.236). This high genetic diversity identified among the subpopulations can be used to develop new wheat cultivars

GWAS revealed effect of genotype × environment interactions for grain yield of Nebraska winter wheat

Background: Improving grain yield in cereals especially in wheat is a main objective for plant breeders. One of the main constrains for improving this trait is the G × E interaction (GEI) which affects the performance of wheat genotypes in different environments. Selecting high yielding genotypes that can be used for a target set of environments is needed. Phenotypic selection can be misleading due to the environmental conditions. Incorporating information from phenotypic and genomic analyses can be useful in selecting the higher yielding genotypes for a group of environments. Results: A set of 270 F3:6 wheat genotypes in the Nebraska winter wheat breeding program was tested for grain yield in nine environments. High genetic variation for grain yield was found among the genotypes. G × E interaction was also highly significant. The highest yielding genotype differed in each environment. The correlation for grain yield among the nine environments was low (0 to 0.43). Genome-wide association study revealed 70 marker traits association (MTAs) associated with increased grain yield. The analysis of linkage disequilibrium revealed 16 genomic regions with a highly significant linkage disequilibrium (LD). The candidate parents’ genotypes for improving grain yield in a group of environments were selected based on three criteria; number of alleles associated with increased grain yield in each selected genotype, genetic distance among the selected genotypes, and number of different alleles between each two selected parents. Conclusion: Although G × E interaction was present, the advances in DNA technology provided very useful tools and analyzes. Such features helped to genetically select the highest yielding genotypes that can be used to cross grain production in a group of environments

Irrigation Practices and Their Effects on Soil Quality and Soil Characteristics in Arid Lands: A Comprehensive Geomatic Analysis

Comprehension of the long-term effects of irrigation on basic soil characteristics and quality is essential for sustainable land management and agricultural production, particularly in arid regions where water availability is limited. This study aimed to investigate long-term irrigation effects on soil quality, soil organic carbon (SOC), and nitrogen (N) stocks in the arid lands of Egypt. Seventy soil samples were collected and analyzed to determine various soil properties. A soil quality index (SQI), SOC, and N stocks were computed. ANOVA and PCA analyses were used to identify signifiant differences between alluvial soils in the southwest part of the investigated area and coastal marine soils in the northeast of the study area. The results demonstrated that most of the studied soil parameters had signifiantly greater values in alluvial compared to coastal marine soils. Long-term irrigation led to an 8.00% increase in SOC and 7.22% increase in N stocks compared to coastal marine soils production. Furthermore, a 39.53% increase was found in the SQI upon longterm irrigation practice. These results suggest that shifting from rain-fed in coastal marine areas to irrigated production systems in alluvial filds can improve soil quality, SOC, and N stocks. Therefore, further studies are required to investigate the impact of additional factors, such as irrigation method and salinity status of sub-surface soil layers, to enhance agricultural productivity and sustainable land use