Amount Of Admixture Research Articles

Local adaptation has a role in reducing vulnerability to climate change in a widespread Amazonian forest lizard.

The extant genetic variation within and among taxa reflects a long history of diversification and adaptive mechanisms in response to climate change and landscape alterations. However, the velocity of current anthropogenic changes poses an imminent threat to global biodiversity. Understanding how species and populations might respond to global climate change provides valuable information for conservation in the face of these impacts. Here, we use genomic data to observe candidate loci under climate selection and test for genetic vulnerability to climate change in a widespread Amazonian ombrophilous lizard population. We found nine populations across Amazonia with a considerable amount of admixture among them. Distinct approaches of genome-environment association analyses revealed 56 candidate single-nucleotide polymorphisms (SNPs) under climatic selection, showing an east-west gradient in the adaptive landscape and a signal of local climate adaptation across the species range. According to our results, signals of local adaptation indicate that the species may not respond equally throughout its range, with some populations facing higher extinction risks. Genomic offset analysis predicts the southern and central portions of Amazonia to have a higher vulnerability to future climate change. Our findings highlight the importance of considering spatially explicit contexts with a large sampling coverage to evaluate how local adaptation and climatic vulnerability affect Amazonian forest ectothermic fauna.

Mix proportion test and engineering characteristics analysis of loess-based cement slurry material

To address the challenges of limited space, quality control issues, and ensuring stable self-compaction of backfill materials in trench backfilling projects, a loess-based cement slurry was developed as a flowable backfill material by using loess as the primary base material and incorporating an appropriate amount of admixture for solidification and improvement. The permeability, collapsibility, and disintegration of the loess-based cement slurry were analyzed by varying the cement content and curing age. The slump test was first conducted to determine the optimal water content for varying cement contents, aiming for a slump of 180 mm. Subsequently, the compressive strength was tested using an orthogonal experimental design. The analysis revealed the optimal mix ratio for the loess-based cement slurry: 8% naphthalene sulfonate formaldehyde condensate, 3% sodium sulfate, 0.5% sodium thiosulfate, and 0.08% ethylene glycol. Experimental results indicated that with 4% cement content, the loess-based cement slurry exhibited a maximum permeability coefficient of 0.977 × 10−5 and a maximum collapsibility coefficient of 0.865 × 10−2, confirming that both permeability and collapsibility meet the required standards. When the cement content exceeds 6%, the cement paste shows minimal collapse. This study offers an efficient and reliable technical solution for backfilling operations in loess regions.

Experimental Investigation of High-Performance Concrete Using Metakaolin and Steel Fibers in Conventional Concrete

Possibly the most extensively utilized building material worldwide is concrete. To address concerns about cost, energy, environmental protection, and resource conservation, the amount of mineral admixture added to cement has significantly increased as the concrete industry has grown. However, pressure has been applied to limit cement use through the use of supplemental materials due to environmental concerns about the harm caused by raw material extraction and carbon dioxide emissions during cement manufacturing. With the increase in demand for construction materials, there is a strong need to utilize alternative materials for sustainable development. The main objective of this investigation is to study the properties, such as compressive strength Metakaolin is used for the project is available in chemical factories. The proportion of cement substitutes by metakaolin and steel fibers has been substituted at 10%+5%, 20%+10%, 30%+15% and 40%+20% respectively. After testing, the cast specimens for 28days curing. The Mechanical and resilience characteristics of the specimens at various ages have been found out.

Application of Carbon Nanotube (CNT) to Improve Mechanical Properties of Concrete: A Comparative Analysis with Superplasticizer

Many researchers' interest in carbon nanotube (CNT) materials has grown as a result of their potential use in the construction industry. This is mostly related to the mechanical, electrical, thermal, kinetic, and chemical properties of CNT, which have a big impact on the way concrete functions. Hydrated calcium silicate is a complex network of binding particles that compose the cement composite material known as concrete. Since it has nanoscale features, CNT will interact most strongly with hydrated calcium silicate, improving the concrete's mechanical qualities. The purpose of this study is to ascertain the impact of adding CNT to concrete mixtures. Three distinct mixes were created by varying the types and amounts of admixtures that were added to the concrete mix. Two mixed variations employed CNT at various doses, while one mixed variation used admixture type F (superplasticizer), and the performance of one was compared to the other. Concrete that was both new and hard underwent specimen testing. On fresh concrete, a slump test was conducted using ASTM C163, while for hard concrete, cylindrical specimens measuring 100 mm x 200 mm were tested for unit weight and compressive strength at 7, 14, and 28 days following ASTM C39. According to the test results, utilizing CNT at a lower dose than the typical superplasticizer dose leads to greater workability and compressive strength. The results of the workability and compressive strength tests will be improved by the inclusion of CNT.

Experimental and Numerical Investigation on the Mechanical Properties of Concrete with High Volumes of Modified Phosphogypsum

The effects of high-temperature modified phosphogypsum (HPG), incorporated at contents of 40%, 50%, and 60%, on the compressive strength and elastic modulus of mortar and concrete were investigated. Additionally, the influence of graded granulated blast furnace slag powder (GGBS), quicklime, and silica fume on the mechanical properties of HPG-based mortar (HPGM) and HPG-based concrete (HPGC) was discussed. Moreover, the microstructure of HPGM was analyzed using scanning electron microscopy (SEM). A two-dimensional mesoscale model of HPGC was developed to predict how variations in HPG content, coarse aggregate characteristics, and interfacial transition zone (ITZ) characteristics influence the compressive strength and elastic modulus of HPGC. The experimental results showed that high volumes of HPG weakened the mechanical properties of HPGM and HPGC, while appropriate amounts of mineral admixtures offset the negative effects caused by calcium hydroxide (Ca(OH)2) crystals and impurities within the system. The simulation results indicated that the maximum deviation between the mesoscale model prediction and experimental data was only 8.38%, which verified the accuracy of the mesoscale model prediction. The compressive strength of HPGC initially decreased and subsequently increased with the rise in the modulus and content of coarse aggregate, whereas it declined with higher HPG dosage and increased ITZ thickness. In contrast, the elastic modulus of HPGC showed a gradual increase with rising coarse aggregate content and improved ITZ mechanical properties, while it decreased as HPG content and ITZ thickness increased.

Utilizing fly ash from coal-fired power plants to improve the utilization of incineration fly ash resources and reduce toxicity

Utilizing fly ash from coal-fired power plants to improve the utilization of incineration fly ash resources and reduce toxicity

Mechanical and autogenous shrinkage properties of coarse aggregate ultra-high performance concrete (CA-UHPC): The effect of mineral admixtures

Mechanical and autogenous shrinkage properties of coarse aggregate ultra-high performance concrete (CA-UHPC): The effect of mineral admixtures

Study on the chloride ion binding rate of sulfoaluminate cement mortars containing different mineral admixtures

In this study, the chloride ion (Cl−) binding rate of sulfoaluminate cement (SAC) mortars containing different mineral admixtures was investigated. This is essential to improve the durability of concrete structures in high Cl− environments, especially where they are susceptible to Cl− attack such as coastlines and marine structures. The effects of Cl− concentration, curing age, and the type and amount of mineral admixture on the Cl− binding rate of SAC mortars were analyzed. It was found that the content of water-soluble Cl− in SAC mortars decreased with the increase of curing age, while the Cl− binding ratio increased accordingly, indicating that its resistance to internal Cl− permeation increased. The addition of fly ash (FA) and ground granulated blast furnace slag (GGBS) can significantly improve the Cl− binding rate of SAC mortars, and the Cl− binding rate increases to 46.6% with 20% of FA and 38.7% with 40% of GGBS. The effects of mineral admixtures on the microstructure and phase composition of SAC mortars were further investigated by X-ray diffraction (XRD) analysis. The results showed that the addition of FA and GGBS promoted the formation of C-S-H (calcium silicate hydrate) gels and improved the resistance of SAC mortars to Cl− penetration. On the other hand, the excessive addition of silica fume (SF) decreased the Cl− binding rate, whereas a moderate amount of limestone powder (LP) improved the Cl− binding rate. The study of the Cl− binding rate of SAC mortars can help to evaluate their resistance to Cl− erosion in real projects, thus guiding the optimization of concrete formulations and the improvement of durability.

Experimental study on mechanical properties and toughness of recycled steel fiber rubber concrete

Experimental study on mechanical properties and toughness of recycled steel fiber rubber concrete

Influence of flocculation with dry-mixing on slump flow of high-strength concrete

The use of high-strength concrete in construction is expected to increase, and the manufacturing technology employed to produce such concrete needs to adapt to this rise. High-strength concrete has a workability that can vary significantly depending on the mixing conditions, even with the same mix design and in the same environment. This research focuses on the change in workability due to dry-mixing (i.e., mixing of fine aggregate with cement in the early stage) in the mixing process of a high-strength concrete mix using a revolving-double paddle mixer. As a result, it was confirmed that the slump flow value difference caused by dry-mixing was about 25 cm. Furthermore, Cryo-SEM (which can observe the specimens in the frozen state) image analysis revealed that dry-mixing causes flocculation of cement particles. The amount of admixtures adsorbed was then analyzed. This study concluded that flocculation affects the degree and timing of admixture adsorption in the later stages of the mixing process, leading to differences in concrete workability.

Fly ash admixture originating from lignite combustion in construction mortars – Time evolution of technical parameters and heavy metals leachability

Fly ash admixture originating from lignite combustion in construction mortars – Time evolution of technical parameters and heavy metals leachability

CHARACTERISTICS OF FLY ASH-BASED GEOPOLYMER MORTAR WITH VARIATION OF TYPES AND DOSAGES OF ADMIXTURE AND CURING SYSTEMS

Geopolymer concrete is the concrete of the future because, in its manufacture, it does not cause environmental problems; instead, it can prevent air pollution and environmental pollution. Geopolymer concrete has several advantages: suitable mechanical properties, high early strength, stable heat, and fire resistance. In the mixture, fly ash, a silicate and aluminum source, is reacted with an alkaline solution as an activator to make a polymerization reaction. To carry out the polymerization reaction, it is necessary to use Sodium Hydroxide or NaOH, which has strong basic properties as an alkaline reactant, and sodium silicate or Na2SiO3 as a catalyst.This study aims to determine the effect of using admixture on the compressive strength of 50x50x50 mm geopolymer mortar cubes. This study's ratio of the alkaline solution was 1/1, while the balance between fly ash/solution was 60/40. Planning a mixture of mortar composition, namely fine aggregate/paste of 65/35. The admixture used is Sikament LN and Sika Viscocrete 1050 HE with a curing system that is humid temperature and at room temperature. Sikament LN content is 0,3%, 1%, 1,5%, and 2% by weight of fly ash, while the Sika Viscocrete 1050 HE content is 0,8%, 1%, 1,5% and 2% by weight of fly ash. Mortar compressive strength test was carried out at 7 days, 14 days, and 28 days.In this study, the optimum grade for each use of admixture in geopolymer mortar was Sikament LN 0,3% and Sika Viscocrete 1050 HE 0,8% at humid temperature curing, which produced the highest compressive strength of 37,65 MPa and 21,26 MPa at 28 days of age. Increasing the percentage level of the amount of admixture used decreases the results of the mortar compressive strength test. The curing system shows that the mortar with the humid temperature curing system produces a higher compressive strength compared to the room temperature curing system. Keywords: Geopolymer, Fly ash, Admixture, Curing System

Finite Element Method Simulation Study on the Temperature Field of Mass Concrete with Phase Change Material

Phase change materials can be converted between solid, liquid, and gaseous states, absorbing or releasing a large amount of heat. PCM is incorporated into concrete to adjust the temperature difference between inside and outside of concrete, which can reduce cracking. In this paper, the finite element analysis method is used to establish the model of an ordinary concrete structure, doped with phase change materials, on the basis of mechanical properties and a temperature regulation test performed by calculating the adiabatic temperature rise of concrete with different contents of composite phase change material, comparing the experimental and simulation results of the ordinary concrete structures with phase change materials, and analyzing the change in temperature field of the concrete structure with the content of self-prepared composite phase change materials. It is found that the addition of self-prepared composite phase change materials reduces the temperature peak of the concrete structure in the stage of hydration heat and delays the time taken to reach the temperature peak. Then, the temperature field of the phase change mass concrete structure is established, and the influence law of composite phase change material admixture on the temperature field of mass concrete is summarized through the time–temperature curves of different admixture amounts and positions so as to predict the possibility of cracks in mass concrete.

Genetic and telomeric variability: Insights from a tropical avian hybrid zone.

Telomere lengths and telomere dynamics can correlate with lifespan, behaviour and individual quality. Such relationships have spurred interest in understanding variation in telomere lengths and their dynamics within and between populations. Many studies have identified how environmental processes can influence telomere dynamics, but the role of genetic variation is much less well characterized. To provide a novel perspective on how telomeric variation relates to genetic variability, we longitudinally sampled individuals across a narrow hybrid zone (n = 127 samples), wherein two Manacus species characterized by contrasting genome-wide heterozygosity interbreed. We measured individual (n = 66) and population (n = 3) differences in genome-wide heterozygosity and, among hybrids, amount of genetic admixture using RADseq-generated SNPs. We tested for population differences in telomere lengths and telomere dynamics. We then examined how telomere lengths and telomere dynamics covaried with genome-wide heterozygosity within populations. Hybrid individuals exhibited longer telomeres, on average, than individuals sampled in the adjacent parental populations. No population differences in telomere dynamics were observed. Within the parental population characterized by relatively low heterozygosity, higher genome-wide heterozygosity was associated with shorter telomeres and higher rates of telomere shortening-a pattern that was less apparent in the other populations. All of these relationships were independent of sex, despite the contrasting life histories of male and female manakins. Our study highlights how population comparisons can reveal interrelationships between genetic variation and telomeres, and how naturally occurring hybridization and genome-wide heterozygosity can relate to telomere lengths and telomere dynamics.

Study on the Effect of Interfacial Modification on the Properties of Super Standard Mica Sand Cement-Based Materials

Mica is a harmful substance in sand and occurs frequently. The application of super standard mica sand is a difficult problem in large-scale engineering. In this work, the effects of an interface modifier, mineral admixture, and a curing system on the properties of cement-based materials with super standard mica sand were studied. The strength of cement-based materials linearly decreases with the mica content in sand. When the mica content in sand exceeds 6%, the compressive strength of mortar and concrete at 28 d decreases by more than 22.3% and 33.5%, respectively. By adding the silane coupling agent (SCA) of 50% mica mass and curing in natural conditions, the compressive strength of mortar increases by 10.9%. The cement-based materials with the SCA are more suitable for curing in natural conditions, and the performance of the SCA will not be affected by adding appropriate amounts of mineral admixture. The drying shrinkage strain of the concrete, with the sand containing high mica content modified by SCA, is reduced by 10.5%, and the diffusion of chloride ions in concrete is reduced. The XRD results show that the addition of the interfacial agent does not change the hydration products. The MIP and SEM results show that the SCA can form a bridge structure between the hydration products and the mica, improve the bonding strength of the interface zone, and reduce the number of harmful pores.

Abstract 2149: West African genetic ancestry and origin of the BRCA1 locus in Jamaican men with high grade prostate cancer

Abstract Introduction: Men of West African (WA) ancestry are at higher risk for prostate cancer than men of European (EU) or Asian descent. Caribbean populations provide an opportunity to identify potential founder mutations that contribute to cancer risk. Jamaica has among the highest rates of prostate cancer incidence and mortality in the world and the majority of the population are of WA ancestry. However, there is a significant amount of genetic admixture of EU and Asian ancestry from historic migration patterns. Thus, the population provides a unique cohort for studying the complex interplay between genetic ancestry and prostate cancer. In this pilot study, we characterized the overall and gene locus-specific ancestry of Jamaican prostate cancer patients to explore potential associations with clinicopathologic disease features. We specifically focused this analysis on the BRCA1 locus based on its known association with inherited prostate cancer risk and also with breast cancer risk in patients from the Caribbean. Methods: A retrospective cohort of 31 Jamaican men (non-US citizens/residents) who travelled to the University of Miami (2015-2020) specifically for robotic prostatectomy were included in the analysis. DNA was prepared from normal prostate tissue and analyzed using the Illumina Global Screening Array version 3 with Multi-Disease Drop-In that includes more than 650,000 genetic markers. Both overall genetic ancestry and allele specific ancestries were determined for each study subject. Clinical and pathological features (age, PSA, stage, grade group (GG)) were also recorded and analyzed using descriptive statistics. Results: Median age was 67 years, median pre-op PSA was 6.7. The majority of patients were cT1c (91%) and GG 2 (29%) on biopsy. On final pathology most men were ≥pT3 (51%) and the proportion of GG 1, 2 and ≥ 3 was 3%, 52% and 45% respectively. The mean overall West African genetic ancestry was 51.2% (SD 28.4%). Overall % West African ancestry was not associated with pathological GG. In contrast, 50% of the men who were homozygous for African ancestry alleles at the BRCA1 locus had high-grade prostate cancer (GG 3, 4, 5) versus 37% of the men with non-African or heterozygous BRCA1 genotypes. Conclusions: In a select cohort of Jamaican men, we found that half of patients with BRCA1 alleles derived from West African ancestry also have high grade prostate cancer. BRCA1 of African ancestral origin may contribute to the relatively high prevalence of aggressive prostate cancer in men from Jamaica. Work in progress focuses on an expanded study of associations between allele-specific genetic ancestry and prostate cancer in high-risk populations. Citation Format: Sandra M. Gaston, Anthony J. Griswold, Oleksandr N. Kryvenko, Tianjie Gu, Guan-Nan Zhang, Nachiketh S. Prakash, Yuval Avda, Tarek Ajami, Chad R. Ritch. West African genetic ancestry and origin of the BRCA1 locus in Jamaican men with high grade prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2149.

Effect of surface treatment by mineral admixture-magnesium potassium phosphate cement on the mechanical properties, durability, and microstructure of recycled aggregate concrete

Effect of surface treatment by mineral admixture-magnesium potassium phosphate cement on the mechanical properties, durability, and microstructure of recycled aggregate concrete

Je modřín opadavý v Nízkém Jeseníku opravdu jesenický? Pohled molekulárních metod

European larch (Larix decidua Mill.) is an important tree species commonly used in managed forests of central Europe. However, its genetic structure, post-glacial range dynamics, and consequent nativity status are poorly understood. Here we provide the first study focusing on the genetic structure of in situ larch populations in the north-eastern Czech Republic using molecular genetics. Most of the studied area is traditionally considered to be a part of the autochthonous native range of the Jeseníky lineage of larch and some of the included populations are protected as belonging to this type. We confirm a common presence of the Jeseníky type and its close evolutionary relation with larch populations from both the Carpathians and Poland. However, we also found important levels of admixture of genetic material from the Alps in all of the analyzed populations. The highest amount of Alpine admixture was found in the populations of intensively managed forests, the proportion of non-native material in the protected areas was relatively lower but still significant. Our results show the importance of populationgenetic research for practical conservation of local populations and lineages even for common species.

Effect of powder–liquid ratio and admixture on properties of metakaolin‐based geopolymer coating

AbstractProtective coating is one of the effective ways to help concrete structures resist environmental erosion. However, most of the existing coating materials are organic compounds, which have the disadvantages of poor durability and high energy consumption. In this study, metakaolin with excellent durability was used as the main raw material, and a flexible and waterproof ethylene‐vinyl acetate emulsion was added to improve the high brittleness characteristics of metakaolin, resulting in a metakaolin‐based geopolymer coating material. Through tests such as water absorption, hardness, gloss, and tensile properties, we investigated the effects of the powder–liquid ratio and the type and amount of admixture on the properties of the coating. The results show that the coating exhibits better performance when the powder‐to‐liquid ratio is 0.6. Based on this, it was found that the optimal dosage of water‐reducing agent, coupling agent, and defoamer was 0.7%, 0.3%, and 0.3%, respectively.

The Influence of Acid Casein on the Selected Properties of Lime-Metakaolin Mortars.

One of the ways to modify selected parameters of lime mortars is the use of biopolymers of animal origin, such as bone glue, skin glue, bovine blood, eggs, and casein. These are protein-based biopolymers. Casein is an example of an organic polymer produced from cow's milk. The aim of the work was to investigate the possibilities of improving selected properties of mortars based on hydrated lime and metakaolin. The mixture was modified with powdered technical casein in amounts of 0.5%, 1.5%, 1%, 1.5%, and 2% as a partial mass replacement for the binding mixture. Additionally, the influence of increasing the amount of water on the properties of the mortar with a casein admixture of 2% was checked. This study examined consistency, shrinkage, water absorption, capillary action, porosity, flexural, compressive strength, and Young's modulus. The admixture of casein influenced the properties of the mortar, but not in all cases, and it was possible to determine a clear trend related to the variable amount of casein. Strength properties deteriorated as the amount of casein increased. When air bubbles were introduced into the mortar after the casein was dissolved, the porosity increased as the amount of admixture increased. The moisture properties improved; namely, casein led to a reduction in water absorption and water absorption caused by capillary action. No relationship was observed between the amount of casein and the drying shrinkage. Increasing the amount of water in the mixture led to the expected effects, i.e., an increase in porosity, shrinkage, and water absorption, and a decrease in mechanical strength.