Substantial deletion overlap among divergent Arabidopsis genomes revealed by intersection of short reads and tiling arrays

A new approach to detect deletions in divergentgenomes combines short read sequencing and tilling array data. Its utility is demonstrated on Arabidopsis strains

Supplementary Cementitious Materials for Concrete: Characterization Needs

peer reviewedA wide variety of materials are currently used as supplementary cementitious materials (SCMs) for concrete, including natural materials and byproducts from various industries. Historically, natural SCMs, mostly derived from volcanic deposits, were common in concrete. In recent years, the dominant SCMs have been industrial by-products such as fly ash, ground granulated blast furnace slag (GGBFS), and silica fume. There is currently a resurgence of research into historic and natural SCMs, as well as other alternative SCMs for many reasons. The primary benefits of SCM use in improvement of long-term mechanical performance, durability, and sustainability are widely accepted, so local demand for these materials can exceed supply. This paper describes some of the SCMs that are attracting attention in the global research community and the properties and characteristics of these materials that affect their performance. Special attention is paid to the importance and demands of material characterization. Many SCMs do not necessarily lend themselves to characterization methods used in standardized test methods, which sometimes fail to describe the properties that are most important in predicting reactivity

A generalist–specialist trade-off between switchgrass cytotypes impacts climate adaptation and geographic range

Polyploidy results from whole-genome duplication and is a unique form of heritable variation with pronounced evolutionary implications. Different ploidy levels, or cytotypes, can exist within a single species, and such systems provide an opportunity to assess how ploidy variation alters phenotypic novelty, adaptability, and fitness, which can, in turn, drive the development of unique ecological niches that promote the coexistence of multiple cytotypes. Switchgrass, Panicum virgatum, is a widespread, perennial C4 grass in North America with multiple naturally occurring cytotypes, primarily tetraploids (4×) and octoploids (8×). Using a combination of genomic, quantitative genetic, landscape, and niche modeling approaches, we detect divergent levels of genetic admixture, evidence of niche differentiation, and differential environmental sensitivity between switchgrass cytotypes. Taken together, these findings support a generalist (8×)–specialist (4×) trade-off. Our results indicate that the 8× represent a unique combination of genetic variation that has allowed the expansion of switchgrass’ ecological niche and thus putatively represents a valuable breeding resource

Reactivity tests for supplementary cementitious materials: RILEM TC 267-TRM phase 1

A primary aim of RILEM TC 267-TRM: “Tests for Reactivity of Supplementary Cementitious Materials (SCMs)” is to compare and evaluate the performance of conventional and novel SCM reactivity test methods across a wide range of SCMs. To this purpose, a round robin campaign was organized to investigate 10 different tests for reactivity and 11 SCMs covering the main classes of materials in use, such as granulated blast furnace slag, fly ash, natural pozzolan and calcined clays. The methods were evaluated based on the correlation to the 28 days relative compressive strength of standard mortar bars containing 30% of SCM as cement replacement and the interlaboratory reproducibility of the test results. It was found that only a few test methods showed acceptable correlation to the 28 days relative strength over the whole range of SCMs. The methods that showed the best reproducibility and gave good correlations used the R3 model system of the SCM and Ca(OH)2, supplemented with alkali sulfate/carbonate. The use of this simplified model system isolates the reaction of the SCM and the reactivity can be easily quantified from the heat release or bound water content. Later age (90 days) strength results also correlated well with the results of the IS 1727 (Indian standard) reactivity test, an accelerated strength test using an SCM/Ca(OH)2-based model system. The current standardized tests did not show acceptable correlations across all SCMs, although they performed better when latently hydraulic materials (blast furnace slag) were excluded. However, the Frattini test, Chapelle and modified Chapelle test showed poor interlaboratory reproducibility, demonstrating experimental difficulties. The TC 267-TRM will pursue the development of test protocols based on the R3 model systems. Acceleration and improvement of the reproducibility of the IS 1727 test will be attempted as well

Rationale and design of a randomised controlled trial evaluating the effectiveness of an exercise program to improve the quality of life of patients with heart failure in primary care : the EFICAR study protocol

Background: Quality of life (QoL) decreases as heart failure worsens, which is one of the greatest worries of these patients. Physical exercise has been shown to be safe for people with heart failure. Previous studies have tested heterogeneous exercise programs using different QoL instruments and reported inconsistent effects on QoL. The aim of this study is to evaluate the effectiveness of a new exercise program for people with heart failure (EFICAR), additional to the recommended optimal treatment in primary care, to improve QoL, functional capacity and control of cardiovascular risk factors. Methods/Design: Multicenter clinical trial in which 600 patients with heart failure in NYHA class II-IV will be randomized to two parallel groups: EFICAR and control. After being recruited, through the reference cardiology services, in six health centres from the Spanish Primary Care Prevention and Health Promotion Research Network (redIAPP), patients are followed for 1 year after the beginning of the intervention. Both groups receive the optimized treatment according to the European Society of Cardiology guidelines. In addition, the EFICAR group performs a 3 month supervised progressive exercise program with an aerobic (high-intensity intervals) and a strength component; and the programme continues linked with community resources for 9 months. The main outcome measure is the change in health-related QoL measured by the SF-36 and the Minnesota Living with Heart Failure Questionnaires at baseline, 3, 6 and 12 months. Secondary outcomes considered are changes in functional capacity measured by the 6-Minute Walking Test, cardiac structure (B-type natriuretic peptides), muscle strength and body composition. Both groups will be compared on an intention to treat basis, using multi-level longitudinal mixed models. Sex, age, social class, co-morbidity and cardiovascular risk factors will be considered as potential confounding and predictor variables. Discussion: A key challenges of this study is to guarantee the safety of the patients; however, the current scientific evidence supports the notion of there being no increase in the risk of decompensation, cardiac events, hospitalizations and deaths associated with exercise, but rather the opposite. Safety assurance will be based on an optimized standardised pharmacological therapy and health education for all the participants

Oxidative discolouration in whole-head and cut lettuce: biochemical and environmental influences on a complex phenotype and potential breeding strategies to improve shelf-life

Lettuce discolouration is a key post-harvest trait. The major enzyme controlling oxidative discolouration has long been considered to be polyphenol oxidase (PPO) however, levels of PPO and subsequent development of discolouration symptoms have not always correlated. The predominance of a latent state of the enzyme in plant tissues combined with substrate activation and contemporaneous suicide inactivation mechanisms are considered as potential explanations for this phenomenon. Leaf tissue physical properties have been associated with subsequent discolouration and these may be influenced by variation in nutrient availability, especially excess nitrogen and head maturity at harvest. Mild calcium and irrigation stress has also been associated with a reduction in subsequent discolouration, although excess irrigation has been linked to increased discolouration potentially through leaf physical properties. These environmental factors, including high temperature and UV light intensities, often have impacts on levels of phenolic compounds linking the environmental responses to the biochemistry of the PPO pathway. Breeding strategies targeting the PALand PPOpathway biochemistry and environmental response genes are discussed as a more cost-effective method of mitigating oxidative discolouration then either modified atmosphere packaging or post-harvest treatments, although current understanding of the biochemistry means that such programs are likely to be limited in nature and it is likely that they will need to be deployed alongside other methods for the foreseeable future

Characterization of supplementary cementitious materials by thermal analysis

Working Group 1 of RILEM TC 238-SCM ‘Hydration and microstructure of concrete with supplementary cementitious materials (SCMs)’ is defining best practices for the physical and chemical characterization of SCMs, and this paper focusses on their thermal analysis. Thermogravimetric analysis (TGA) can provide valuable data on the chemical and mineralogical composition of SCMs. Loss-on-ignition (LOI) testing is a commonly used, standardized, but less sophisticated version of TGA that measures mass at endpoints only, with heating generally in air. In this paper we describe the use of TGA and LOI to characterize Portland cement with limestone additions, coal combustion fly ashes, ground-granulated blast furnace slag, calcined clays, and natural pozzolans. This paper outlines the value and limitations of TGA and LOI (in the formats defined in different standards regimes) for material characterization, and describes testing methods and analysis. TGA testing parameters affect the mass loss recorded at temperatures relevant for LOI measurements (700–1000 °C) of slags and fly ashes, mainly associated with oxidation reactions taking place upon heating. TGA of clays and natural pozzolans is utilized to identify optimal calcination conditions leading to dehydroxylation and consequent structural amorphization, particularly for kaolinite. However, dehydroxylation and amorphization do not occur at similar temperatures for all clays, limiting the applicability of TGA for this purpose. Although TGA is widely utilized for characterization of SCMs, the testing parameters significantly affect the results obtained, and TGA results require careful interpretation. Therefore, standardization of TGA testing conditions, particularly for LOI determination of slags and fly ashes, is required

The Future of Concrete may be in its past

Presented by: Dr. Maria Juenger Professor of Civil Engineering The University of Texas at Austin The concrete industry is under increasing pressure to reduce the energy used in production of portland cement and the associated greenhouse gas emissions. There are several possible ways to address this challenge, but the most straightforward is to minimize the amount of portland cement used by substituting other materials to make concrete binders. We can learn a lot from the Romans, who made strong, durable concrete without any portland cement at all (though not without greenhouse gas emissions!). We are entering a natural pozzolan renaissance, where the industry is searching far and wide for alternative cementitious materials, including those that mimic the Roman pozzolana. This presentation will address current research on alternative concrete binders, including the characteristics and performance of North American natural pozzolans. Bio: Dr. Maria Juenger is Professor and John A. Focht Centennial Teaching Fellow in the Department of Civil, Architectural, and Environmental Engineering at the University of Texas at Austin, where she has been since 2002. She is a fellow of the American Ceramic Society and the American Concrete Institute. Dr. Juenger received her B.S. degree in Chemistry from Duke University and Ph.D. in Materials Science and Engineering from Northwestern University. After completing her Ph.D., she was a postdoctoral researcher in Civil Engineering at the University at California, Berkeley. Dr. Juenger’s teaching and research focus on materials used in civil engineering applications. She primarily examines chemical issues in cement-based materials; these include phase formation in cement clinkering, hydration chemistry of portland cement, calcium sulfoaluminate cement, and supplementary cementitious materials, and chemical deterioration processes in concrete. In 2005 she received a Faculty Early CAREER Award from the National Science Foundation. She has received several awards from the American Concrete Institute for her research, teaching, and service, including the Walter P. Moore, Jr. Faculty Achievement Award in 2009, the Young Member Award for Professional Achievement in 2010, the Wason Medal for Materials Research in 2011. She is currently chair of American Concrete Institute committee 236 - Material Science of Concrete and is a member of the RILEM technical committee on supplementary cementitious materials

Identifying glass compositions in fly ash

In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS), calcium aluminosilicate glasses (CAS), a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity

Modeling hydration of cementitious systems

Concrete performance, including strength, susceptibility to delayed ettringite formation, and residual stress development are dependent on early-age temperature development. Concrete temperature prediction during hydration requires an accurate characterization of the concrete adiabatic temperature rise. This study presents the development of a model for predicting the adiabatic temperature development of concrete mixtures based on material properties (for example, cement chemistry and fineness and supplementary cementitious materials (SCM) chemistry), mixture proportions, and chemical admixture types and dosages. The model was developed from 204 semi-adiabatic calorimetry results and validated from a separate set of 58 semi-adiabatic tests. The final model provides a useful tool to assess the temperature development of concrete mixtures and thereby facilitate the prevention of thermal cracking and delayed ettringite formation in concrete structures