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Hmongcentric Niche Charter Schools: The Role of Social Capital on Students’ Perceived Academic Competence
No full textUsing Coleman’s (1988) social capital theory, this study investigated the connection between family and school social capital and the perceived academic competence of students enrolled in Hmongcentric niche charter schools. The study analyzed 124 participants consisting of third, fourth, and fifth-grade students residing in Minnesota, with 93% identifying as Hmong. Results of structural equation modeling showed that school social capital, as measured by school attachment and school connection, is significantly linked to students’ perceived academic competence. Further analyses suggested that school attachment, especially in charter schools that focus on culture and language, plays a more crucial role in shaping students’ perceived academic competence. However, no significant association was found with family and extended family social capital. The study concludes by discussing implications for future research and how school attachment can inform educational policies and practices to support student success
Improving Fatigue Strength And Life Of Single Crystal CMSX-4
No full textThe deep penetration of laser peening (LP) and retention of residual stress at high temperature by LP is significant in improving fatigue life and strength of superalloys exposed to high temperature and corrosion. Single crystal CMSX-4, was evaluated for stress relaxation and both fatigue life and fatigue strength of material that was LP-treated compared to non-LP and shot-peened (SP) specimens. LP was done with multiple layers using a 20 J/pulse laser where the laser high energy enabled using a 5 mm spot size on the metal surface. Stress measurements by the slitting technique showed the plastic penetration depth exceeded SP by a factor of 24. Un-peened and peened specimens were exposed to sulphate corrosives at 700°C for 300 hours and then fatigue tested. Five non-LP specimens all failed in low cycle fatigue whereas three identically tested LP specimens all achieved multi-million-cycle runout, indicating a consistent large benefit for life by LP. Tests of fatigue strength gave improvement of 2:1 for laser peened specimens. Measurements post hot-corrosion exposure and fatigue testing showed 5 mm depth retention of residual eigenstress for LP specimens
E-Strip® Peening Intensity Sensor - Linearity, Variability And Connectivity
No full textThis paper presents the E-Strip®, a novel electronic sensor developed by Shockform to digitally measure shot peening intensity at the part level. Motivated by the limitations of traditional Almen strips—namely, manual handling, time consumption, and susceptibility to human error—the E-Strip® offers a faster, more reliable, and connected alternative. Extensive testing confirmed the E-Strip® output maintains excellent linearity with Almen intensity across a wide range of media and impact levels (R² \u3e 0.997), and its adjustable sensitivity ensures compatibility from low to high intensities. Variability studies showed the E-Strip® provides similar or better consistency than Almen strips at low intensities, although higher variability was observed at higher intensities due to the sensor’s greater responsiveness to process changes. Integrated wireless connectivity and an open API enable automated feedback and real-time process control in Industry 4.0 environments. These advantages position the E-Strip® as a transformative solution for modernizing peening operations
Enhancing The Fatigue Strength Of AM Materials Via Mechanical Surface Treatment
No full textAdditive manufacturing (AM) processes, while enabling the production of intricate geometries, frequently result in suboptimal surface quality, which can significantly restrict the fatigue strength of components when compared to those manufactured using traditional methods. This study explores the effectiveness of mechanical surface treatment (MST) techniques, specifically shot peening and deep rolling, in enhancing the fatigue performance of additively manufactured AlSi10Mg and 316L alloys. A combination of experimental investigations and finite element simulations was employed to evaluate the influence of these treatments on surface integrity, microstructure, and fatigue life. The results reveal that both MST approaches lead to substantial improvements in fatigue strength. Notably, for AlSi10Mg, there was an observed enhancement in fatigue strength of at least 20%, companied by a significant increase in the slope of the S-N curve by at least 50%. These findings highlight the potential of MST methods to effectively address surface defects and improve the overall durability and reliability of components produced through additive manufacturing, thereby expanding their applicability in demanding engineering fields
Knowledge of morphological structure and its connection to reading and writing
No full textWithin the body of literature that provides sound evidence of reading and writing development and disorders, knowledge of morphological structure has been found to play a crucial role. Specifically, awareness of morphological structure (e.g., morphological awareness) serves as an avenue for improving vocabulary, word reading, spelling and reading comprehension. This research brief provides an overview of morphology and morphological awareness, why it is important for reading and writing, how morphological awareness contributes to the aforementioned skills, and considerations for non-native English speakers
Agro-Waste Ash as an Alkaline Activator for Zero-Portland Cement Mortars
No full textAlkali-activated binders (AAB) are known for their reduced global warming potential compared to traditional portland cement-based binders. However, their adoption has been hindered by practical challenges such as high cost and causticity of activators, which limits their use in the field. This study explores an approach using biomass ash derived from agricultural waste, such as almond shells and hulls, as an activator to replace chemicals. Preliminary results indicate that AAB mortars activated with almond shells reach compressive strength comparable to carbonate-activated control and 30-40% higher than hydroxide-activated mortar. Paver blocks and concrete were prepared with compressive cylinder strengths over 30 MPa. Challenges with these materials largely revolve around reducing dry shrinkage, setting time. The findings can be extended to other agro-waste products with high potassium or sodium content in their ashes, diverting more ashes from landfills and promoting a circular economy
Effect of aragonite aspect ratio on the hydration behavior of cementitious materials
No full textThe three polymorphs of calcium carbonate (CaCO₃) affect cement hydration differently. Aragonite’s needle-like shape provides extra nucleation sites and accelerates hydration, but the effect of its aspect ratio is still unclear. This study investigates the influence of aragonite with different aspect ratios on the hydration behavior of cementitious materials. Aragonite with different aspect ratios was synthesized under laboratory conditions by adjusting solution concentrations and reaction parameters. The morphology and phase composition of the synthesized aragonite were characterized using electron microscopy (SEM) and X-ray diffraction (XRD). The synthesized aragonite particles were used to replace 5% and 10% of OPC by weight to evaluate their effects on hydration
Advances in Carbon Capture and Utilization for Production of Binders and Aggregate
No full textThis paper examines various carbon capture and utilization strategies for the decarbonization of cement and concrete, including carbon mineralization and integrated CO2 capture and utilization for the production of supplementary cementitious materials (SCMs), alternative binders, and artificial aggregates, as well as other emerging solutions
Proportioning and curing optimization of carbonated calcium silicate-based materials via machine learning and genetic algorithm
No full textCalcium silicate can react with CO2 in the presence of water to gain strength and thus can be both taken as an alternative binder and a carbon sink. A series of calcium silicates exists in industrial products and natural rocks with diverse material properties, implying its promising sustainable potential and yet foreseeable obstacles in quality control. To tackle that, a data-driven prediction-optimization computational framework was proposed based on a high-fidelity dataset of carbonated calcium silicate-based materials. Ensemble machine learning models were built based on the curated data for CO2 uptake and strength predictions. Pareto front searching was further conducted using a genetic algorithm to pursue better sustainability, strength, and curing efficiency of the materials. Reasonable decisions can be made once the trade-offs are considered among the optimal solutions
Converting olivine into a novel Mg-based cement for carbon sequestration
No full textNatural Mg-rich olivine could potentially serve as a scalable feedstock for Mg-based cements with zero CO2 emissions. This study explores an innovative synthesis of a Mg-based cement by directly reacting olivine with oxalic acid (H2C2O4). The hydration behaviors and cementitious properties of olivine–oxalic acid blends are investigated, as a function of olivine-to-oxalic acid (OL/OA) weight ratio. Higher OL/OA ratio results in faster hydration, while the best compressive strength with up to 32 MPa is obtained at a moderate OL/OA ratio of 3.5 after 28 days. The obtained cements are composed of residual olivine minerals and a dense and compact glushinskite (MgC2O4·2H2O) matrix intermixed with randomly dispersed amorphous silica nanoparticles. The acid–base reaction between Mg-rich olivine and oxalic acid also provides an efficacious strategy for carbon sequestration, as up to 25 wt% of CO2 equivalent can be taken up in hydrated solid phase, potentially rendering this cementitious system carbon negative