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Coarse aggregate sources must possess sufficient level of quality to meet both initial design as well as long-term and life-cycle performance requirements for pavement construction. Morphological shape properties, mineralogy, and chemical properties of the aggregate particles can significantly influence their quality and performance in terms of both durability and mechanical properties. As part of this study, a survey was sent out to different highway agencies to collect representative coarse aggregate samples as well as information regarding different practices used by them for morphological, petrographic, and chemical characterizations of aggregate sources. Morphology analysis using machine vision technology was incorporated to identify shape properties of the collected aggregate samples. Additionally, thin section optical petrographic analysis using an Axioscan 7 full slide scanner was utilized to identify mineral composition of the aggregates. Finally, chemical testing and analysis was conducted using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to detect major element compositions in epoxy impregnated sample of aggregate particles. Statistical analysis including Pearson correlation and multiple regression were deployed to investigate the relationship between the parameters representing mineralogy, chemical, and morphological shape properties. The findings of this study indicated 12 minerals and seven chemical elements with statistical significance to impact the imaging-based shape indices of aggregates. Subsequently, regression-based prediction models were developed to estimate the aggregate shape indices using mineralogy and chemical properties with a relatively satisfactory performance. The improvements in objectively characterizing aggregate chemical, mineralogical, and shape properties can be used to develop improved and sustainable aggregate production methods and specifications. 

Abstract We present a novel approach for mapping vertical uplifts in exhumed metasedimentary rocks by coupling Raman spectroscopy of carbonaceous material with (U-Th)/He thermochronometry on apatite and zircon. We apply this approach to carbonaceous metasedimentary rocks of the Franciscan subduction complex, exposed in the Nacimiento block of central California, USA, an area that records high-pressure–low-temperature metamorphism prior to entrainment within the present-day transform plate boundary. We reveal the extent and magnitude of previously unrecognized exhumation gradients, which, combined with regional structural observations, can be used to quantify vertical crustal motion associated with localized transpression. We propose that the Nacimiento block was affected by a kilometer-scale, post-subduction thermal anomaly linked to a localized transpressive regime since ca. 25 Ma, with an uplift rate of ∼0.3 mm/yr. 

Since its inception in the late 1980s, the delivery of exogenous nucleic acids into living cells via high-velocity micro-projectiles (biolistic, or micro-particle bombardment) has been an invaluable tool for both agricultural and fundamental plant research. Here, we review the technical aspects and the major applications of the biolistic method for studies involving transient gene expression in plant cells. These studies cover multiple areas of plant research, including gene expression, protein subcellular localization and cell-to-cell movement, plant virology, silencing and the more recently developed targeted genome editing via transient expression of customized endonuclease. 

Genetic transformation of host plants by Agrobacterium tumefaciens and related species represents a unique model for natural horizontal gene transfer. Almost five decades of studying the molecular interactions between Agrobacterium and its host cells have yielded countless fundamental insights into bacterial and plant biology, even though several steps of the DNA transfer process remain poorly understood. Agrobacterium spp. may utilizs different pathways for transfer of its DNA, which likely reflects the very wide host range of Agrobacterium. Moreover, closely related bacterial species, such as rhizobia, become able transfer DNA to host plant cells when they are provided with Agrobacterium DNA transfer machinery and T-DNA. Homologs of Agrobacterium virulence genes are found in many bacterial genomes, but only one non-Agrobacterium bacterial strain, Rhizobium etli CFN42, harbors a complete set of virulence genes and can mediate plant genetic transformation when carrying a T-DNA-containing plasmid.