Study Investigating the Influence of Warm-Mix Asphalt Additives on Rutting and Fatigue Performance of Nano-Modified Asphalt Binders

The current study investigates the synergized effect of a nanomaterial and two warm mix additives asphalt (WMA) additives on different properties of asphalt binders. The study used an optimal percentage of 2% for nano-Al2O3; two WMA additives were used in different concentrations. The results revealed that the addition of WMA additives increased the softening point of nano-Al2O3 modified asphalt binder. Penetration and ductility results showed a decrease after the introduction of WMA additives. The viscosity of nano-Al2O3 modified asphalt binders showed a reduction after the introduction of WMA additives. Rutting evaluation was done by using the superpave rutting parameter and multiple stress creep and recovery (MSCR) test. The fatigue performance of the asphalt binders was measured using the superpave fatigue parameter and linear amplitude sweep (LAS) test. Results showed that the introduction of WMA additives improved the rutting and fatigue performance of nano-Al2O3 modified asphalt binders. The introduction of WMA additives enhanced the aging performance of the nano-Al2O3 modified asphalt binders.

Stress Misassignment in the Pronunciation of English by Arabic-speaking Learners: Erratic Practice or Crosslinguistic Influence?

The role of L1 interference in English stress assignment produced by Arabic-speaking EFL learners has received little research attention. This study aims to investigate whether faulty stress assignment by Arab learners is arbitrary or systematic. It also attempts to discover a linkage, if any, between Arabic phonotactic rules of stress placement and stress misplacement in English by Saudi learners. 120 learners from Prince Sattam bin Abdulaziz University were randomly chosen from 3 different levels of English proficiency (lower-intermediate, upper-intermediate, advanced); they were asked to pronounce 72 stimulus words that covered all morpho-syllabic word structures that the learners often mispronounced. The recordings were analysed using WASP spectrogram software and also by two independent raters. Results strongly indicated that crosslinguistic influence may have caused the learners to consistently a) place the stress on a specific syllable in a word even when this word has multiple stress assignments with a difference in meaning, b) stress the second item in a compound noun instead of the first, c) place the stress on the penultimate syllable of most polysyllabic words, d) place the stress on the second syllable of contracted negative auxiliary verbs , and e) misplace stress irrespective of their level of English proficiency.

Multiple Stress Creep Recovery (MSCR) Test for Determination of Waste Engine Oil Modified Asphalt Binder as Pavement Material

Engineers have been using modified binders to improve the quality of flexible pavements. The use of waste material is one of the solutions taken in this direction. It is for this ground that the studies emphasis on the evaluation of waste engine oil as a modifier for asphalt binder as a pavement material. In the study uses four samples extracted from 80/100 penetration grade bitumen. From four sample first sample was checked for weather requirements of asphalt binder meet or not and the three were modified with different content of engine oil (3,6 and 9%). The behaviors of both unmodified and modified binder were checked for rheological properties. Dynamic shear rheometer (DSR) was used to determine high temperature performance grade (PG) and multiple stress creep recovery tests to determine rutting resistance properties of the binder. PG analysis indicates that both aged and un-aged 3% and 6% modified binder have similar higher PG grade with the unmodified one and 9% modified to have lower PG vale. Jnr3.2 value of modified asphalt binder is lower than unmodified binder indicating that modification had improved the rutting resistance and design traffic load (ESALS). The study shows that it is possible to use waste engine oil-modified binder as a pavement material.

Genotypic and phenotypic portrait of Candida albicans clinical isolates colonizing the airways of patients with cystic fibrosis

Candida albicans colonizes the respiratory tract of patients with Cystic Fibrosis (CF). It competes with CF-associated pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, and contributes to disease severity. We serially recovered 160 C. albicans clinical isolates over a period of 30 months from the sputum of 23 pediatric and 2 adult antifungal-naive CF patients at Children’s Hospital Tunis and characterized the genotype and phenotype of a subset of strains using multilocus sequence typing (MLST) and growth assays on multiple stress-, filamentous growth- and biofilm-inducing media. Out of 16 patients regularly sampled for at least 9 months, 8 and 4 were chronically and transiently colonized with C. albicans, respectively. MLST analyses of 56 strains originating from 15 patients indicated that each patient was colonized with a single strain, while 8 patients (53%) carried isolates from clade 4 known to be enriched with strains from Middle East-Africa. A subset of these isolates with the same sequence type and colonizing 3 unrelated patients displayed altered susceptibility to cell wall-perturbing agents, suggesting changes in cell wall structure/function during growth in the CF lung. We also observed differential ability to filament and/or form biofilms in a set of identical isolates from clade 10 sampled over a period of 9 months in a pediatric CF patient, suggesting alterations in phenotypes associated with virulence. Our findings will rely on future whole-genome sequencing analyses to identify polymorphisms that could explain the emergence of new traits in C. albicans strains thriving in the CF host environment.

β-Cyclocitral, a Master Regulator of Multiple Stress-Responsive Genes in Solanum lycopersicum L. Plants

β-cyclocitral (βCC), a major apocarotenoid of β-carotene, enhances plants’ defense against environmental stresses. However, the knowledge of βCC’s involvement in the complex stress-signaling network is limited. Here we demonstrate how βCC reprograms the transcriptional responses that enable Solanum lycopersicum L. (tomato) plants to endure a plethora of environmental stresses. Comparative transcriptome analysis of control and βCC-treated tomato plants was done by generating RNA sequences in the BGISEQ-500 platform. The trimmed sequences were mapped on the tomato reference genome that identifies 211 protein-coding differentially expressed genes. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis and their enrichment uncovered that only upregulated genes are attributed to the stress response. Moreover, 80% of the upregulated genes are functionally related to abiotic and biotic stresses. Co-functional analysis of stress-responsive genes revealed a network of 18 genes that code for heat shock proteins, transcription factors (TFs), and calcium-binding proteins. The upregulation of jasmonic acid (JA)-dependent TFs (MYC2, MYB44, ERFs) but not the JA biosynthetic genes is surprising. However, the upregulation of DREB3, an abscisic acid (ABA)-independent TF, validates the unaltered expression of ABA biosynthetic genes. We conclude that βCC treatment upregulates multiple stress-responsive genes without eliciting JA and ABA biosynthesis.

Adoption of complementary climate-smart agricultural technologies: lessons from Lushoto in Tanzania

Background Agriculture is important for economic growth and development in many countries in Sub-Saharan Africa, including Tanzania. However, agricultural production and productivity remain relatively low, with significant yield gaps attributed to factors such as limited access to and low adoption of appropriate agricultural technologies, and climate-related risks resulting from climate variability and change. This paper explores the drivers of adoption of climate-smart agricultural (CSA) technologies and practices, taking into account the complementarity among agricultural technologies and heterogeneity of the farm households, using data from Lushoto in Tanzania. Methods We use a Multivariate Probit analysis of cross-sectional data collected from 264 smallholder farmers in Lushoto—a climate hotspot in Tanzania—to understand the drivers of household decisions to adopt CSA technologies and practices. The technologies included diversification of multiple stress (drought, floods, pests, diseases)-tolerant crop varieties, use of fertilizers, and application of herbicides and pesticides. The Multivariate Probit model was preferred as it takes into account the inter-relationships of the technologies as well as heterogeneity of the smallholder farmers for more robust estimates. The independent variables used in the analysis included household socio-economic factors such as the relative importance of crop and livestock enterprises, household land size, social capital, access to agricultural credit and weather information, previous experience with fertilizer use and household characteristics (age, education and gender of household head, and household size). Results About 63% of the households diversified their crop enterprises, shifting to improved resilient crops and crop varieties. Another 37% adopted fertilizers, while 38% applied pesticides and herbicides. Conditional on the unobservable heterogeneity effects, the results show that household adoption decisions on diversification of multiple stress-tolerant crops and crop varieties, fertilizer, and pesticides and herbicides are complementary. In addition, the results confirm existence of unobserved heterogeneity effects leading to varying impact of the explanatory variables on adoption decisions among farmers with similar observable characteristics. Conclusions The findings indicate that any effective CSA technology adoption and diffusion strategies and policies should take into account the complementarity of the technologies and heterogeneity of the smallholder farmers. Therefore, inter-related technologies should be promoted as a package or bundled while taking into consideration household and farm-level constraints to adoption.

Genetic Approaches to Enhance Multiple Stress Tolerance in Maize

The multiple-stress effects on plant physiology and gene expression are being intensively studied lately, primarily in model plants such as Arabidopsis, where the effects of six stressors have simultaneously been documented. In maize, double and triple stress responses are obtaining more attention, such as simultaneous drought and heat or heavy metal exposure, or drought in combination with insect and fungal infestation. To keep up with these challenges, maize natural variation and genetic engineering are exploited. On one hand, quantitative trait loci (QTL) associated with multiple-stress tolerance are being identified by molecular breeding and genome-wide association studies (GWAS), which then could be utilized for future breeding programs of more resilient maize varieties. On the other hand, transgenic approaches in maize have already resulted in the creation of many commercial double or triple stress resistant varieties, predominantly weed-tolerant/insect-resistant and, additionally, also drought-resistant varieties. It is expected that first generation gene-editing techniques, as well as recently developed base and prime editing applications, in combination with the routine haploid induction in maize, will pave the way to pyramiding more stress tolerant alleles in elite lines/varieties on time.