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Understanding the effects of elevated temperatures on wood composites
No full textWith the increasing incidence of wildfires, particularly across the western United States, the risk of structural damage to buildings has become a significant concern. Effective fire-resistant design hinges on a detailed understanding of how building materials respond under fire conditions. While not all structural elements in a building are directly exposed to flames, temperatures can exceed 1000°C during flashover events. Therefore, understanding the thermal performance of wood-based materials, especially below their ignition threshold, is crucial to ensure structural integrity, enabling adequate time for occupant evacuation and firefighter intervention.
This research investigates both conventional materials, such as Plywood and Oriented Strand Board (OSB), and newer engineered wood products, specifically Cross-Laminated Timber (CLT), which is gaining popularity in mid- to high-rise wood construction. Characterizing the mechanical properties of sheathing materials is vital for predicting their behavior within wall or floor assemblies during fire exposure. The study focused on the bending properties of plywood, examining both immediate and residual effects of high temperatures, and assessed the primary creep behavior of both plywood and OSB at elevated temperatures. Exposure to temperatures exceeding 170°C resulted in notable strength reduction and increased deflections. Observed trends align with previous studies, such as the limited impact of elevated temperatures on the modulus of elasticity (MOE) compared to other properties. Various numerical models were developed to simulate these properties over different time and temperature scenarios, facilitating model accuracy comparisons.
Critical structural support elements, such as I-joists, also play an essential role in fire resilience, particularly in floor assemblies where enhanced fire protection is often required. This study evaluated the compressive properties of wood composite I-joists under elevated temperatures, identifying failure modes related to OSB buckling and noting diminished compressive strength at temperatures above 180°C. Findings indicated minimal variation in response across different exposure durations. A predictive model was constructed to estimate I-joist compressive performance under both moderate and extreme temperature conditions.
The study further investigated adhesive behavior at elevated temperatures, focusing on those used in Cross-Laminated Timber (CLT) construction. CLT is known to be susceptible to heat-induced delamination, which can compromise fire performance. Various wood and mass timber adhesives were analyzed to understand their stability under high-temperature exposure, with a particular focus on heat delamination risks. Results showed that polyurethane (PUR) adhesives had the lowest thermal stability, while phenol-resorcinol-formaldehyde (PRF) adhesives demonstrated superior resilience, corroborating findings from large-scale fire tests. This research supports the development of a bench-scale test to generate preliminary data on different adhesives, simulating the conditions that may lead to heat delamination
Fertilizing lawns [2013]
No full textRevised 2013.
Fertilizing, along with mowing and irrigating, is one of the basic cultural practices used to produce healthy, dense, green lawns. The goals of this publication are to help you better understand the following:
Reasons for fertilizing
Optimum application rates and timing
Types of fertilizer materials
How to read a fertilizer label
Application techniques
How to avoid turf damage and environmental pollution resulting from improper fertilization
Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: https://extension.oregonstate.edu
Reducing the manual effort of data integration in low- to no- training data environments
No full textThere is a recognized need to collect and connect information from a variety of data sources. However, a lot of manual work is required to find and translate many disparate pieces of information into a cohesive whole. Existing methods either require a significant amount of training data (which is often not available) or have limited expression in terms of their data translation language. This dissertation focuses on low- to no- training data environments for two important problems in data integration: 1) automatically collecting related information from different data sources, and 2) reconciling structural and semantic differences between data sources. For the first problem, we present methods for learning relevant-information-gathering queries online, allowing users to get answers while the system collects training data. Through simulation, we show that these methods can learn effective querying strategies given relatively few pieces of feedback. Further, we present a method for learning queries using rich representations of tuples generated from pretrained LLMs. For the second problem, we explore different LLM-based approaches for mapping metadata information across different relations while requiring no additional model training, extending existing approaches to handle more complex source-to-source translations
From the ocean to our kitchen table : anthropogenic particles in the edible tissue of U.S. West Coast seafood species
No full textMicroplastics (MPs) and other anthropogenic particles (APs) are pervasive environmental contaminants found throughout marine and aquatic environments. We quantified APs in the edible tissue of black rockfish, lingcod, Chinook salmon, Pacific herring, Pacific lamprey, and pink shrimp, comparing AP burdens across trophic levels and between vessel-retrieved and retail-purchased individuals. Edible tissue was digested and analyzed under a microscope, and a subset of suspected APs was identified using spectroscopy (μFTIR). Anthropogenic particles were found in 180 of 182 individuals. Finfish contained 0.02–1.08 AP/g of muscle tissue. In pink shrimp (Pandalus jordani), the average AP/g was 10.68 for vessel-retrieved and 7.63 for retail-purchased samples; however, APs/g of tissue were higher in retail-purchased lingcod than vessel-retrieved lingcod, signaling possible added contamination during processing from ocean to market. Riverine young adult Pacific lamprey contained higher concentrations of APs (1 AP/g ±0.59) than ocean phase adults (0.60 AP/g ±0.80 and p = 0.08). Particle types identified were 82% fibers, 17% fragments, and 0.66% films. These findings suggest a need for further research into technologies and strategies to reduce microfiber pollution entering the environment
The role of the KCS gene family in the variation of Populus trichocarpa drought tolerance
No full textImproving water use of crops is important as the climate continues to warm. Increasing vapor pressure deficits as well as more extreme drought events put pressure on the water use of plants. The KCS locus, an ancient gene family, has been demonstrated to be associated with stomatal traits as well as water use efficiency. KCS genes are therefore a promising target for understanding drought response in plants. The purpose of this study was to assess the link between genes at the KCS locus and hydraulic traits. We analyzed xylem vulnerability to embolism, turgor loss point, and hydraulic safety margin in the model woody tree, Populus trichocarpa, using KCS knockout genotypes created using CRISPR-Cas9 technology. Analysis revealed statistically insignificant trends in P50, P88, and HSM, where WT and KCSall showed values associated with reduced drought tolerance compared to KCS1 and CTR. We additionally examined the relationship between treatment group and tree height on πtlp, which revealed a statistically significant interaction effect, indicating πtlp changes differently as a response to height depending on treatment group. This study lays the groundwork for future work exploring the role of KCS genes and hydraulic traits.Keywords: KCS, drought tolerance, hydraulic traits, Populus trichocarp
Inhibition of the sphingolipid pathway alters symbiosis establishment in a cnidarian-algal association
No full textCoral reefs have progressively declined due to bleaching caused by environmental stressors, drastically impacting the underwater ecosystem they are found in. These stressors also disrupt the symbiosis between cnidarian hosts and Symbiodiniaceae algae essential for long-term host survival and growth. Studying corals within laboratory settings remains difficult, therefore the use of model organisms are supplemented to better understand the symbiotic relationship. Emerging research has suggested that sphingolipid metabolism plays a central role in regulating symbiont uptake, maintenance, and stress responses, yet the functional roles of specific enzymes within this pathway remain relatively understudied. In this experiment, I use the sea anemone Exaiptasia diaphana, commonly known as Aiptasia, to study how disruption of the sphingolipid pathway affects the establishment of algal symbiosis. This is done through targeted pharmacological inhibition of four key enzymes: sphingosine kinase (SPHK), serine palmitoyltransferase (SPT), acid ceramidase (ACDase), and ceramide synthase (CerS). Dose-response assays were done to identify non-lethal working concentrations for each inhibitor which were then used in a 21-day inoculation experiment, quantifying symbiont density through fluorescent microscopy and ImageJ-based analysis. Results demonstrated impaired symbiont acquisition and reduced proliferation when SPHK and SPT were consistently inhibited, indicating that both sphingosine-1-phosphate (S1P) mediated survival signaling and ceramide biosynthesis are required for stable colonization. ACDase inhibition using Carmofur produced mixed, dose-dependent effects reflecting its irreversible toxicity. In contrast, Fumonisin had minimal impact suggesting functional redundancy among CerS isoforms in Aiptasia. Overall, this study identifies how disrupting distinct enzymes of the sphingolipid pathway alters symbiosis establishment and may contribute to further understanding its significance in symbiosis.Keywords: Symbiosis, Cnidaria, Exaiptasia diaphana, Sphingosine rheostat, Sphingolipid metabolis
Role of Minor Alloying Elements and Impurities on the Kinetics of Long-Range Ordering in Ni-Cr-Based Alloys
No full textThere is growing concern about long-range ordered Ni2Cr phase forming during thermal aging of Ni-Cr-based alloys (e.g., 690, 625), which leads to lattice contraction, hardening, and embrittlement, possibly limiting the service life of light water reactor components. The timespan when this phase transformation occurs can vary in orders of magnitude between model and commercial alloys and is likely related to the presence of major (e.g., Fe, Mo) and minor alloying elements (e.g., Ti, Si, Nb). These minor alloying elements have been hypothesized to bind with vacancies and therefore limit diffusion. Contrarily, impurities (e.g., P, S) are believed to enhance vacancy diffusion and accelerate the Ni2Cr phase transformation because of a vacancy drag mechanism. This study implements first principal methods using the five-frequency method and experimental isothermal aging of model Ni-Cr binary and Ni-Cr-X ternary alloys, where X is Ti, Si, Nb, and P to help understand how each minor alloying element affects the Ni2Cr phase transformation timeline. Synchrotron-based X-ray diffraction and hardness measurements are used to quantify the evolution of the Ni2Cr phase transformation through a variety of short aging times to identify the onset of long-range order. In addition, differential scanning calorimetry is used to understand the specific disorder to ordering pathway for both Ti and P. Experimental results are compared to first principles simulations to understand the mechanism by which each element impacts vacancy diffusion and the formation of the long-range ordered phase, Ni2Cr