Flexural strength and ductility of reinforced normal- and high-strength concrete beams

A number of singly reinforced concrete beams made of normal- and high-strength concretes were tested under monotonically increasing loads to study their flexural behaviour and to compare the flexural ductility of normal- and high-strength concrete beams. The flexural strength results verified that British Standard BS 8110, after modification as per the recommendation of The Concrete Society Technical Report 49, is reasonably accurate for application to high-strength concrete beams. On the other hand, the flexural ductility results revealed that the major structural parameters determining the ductility of singly reinforced beams are: (1) for given materials, the tension steel ratio; and (2) in more general cases, the tension steel to balanced steel ratio and the concrete grade. Based on the available test results, a simple formula for predicting the ductility of normal-and high-strength concrete beams is developed. Lastly, in order to avoid brittle failure, it is proposed to set a maximum limit to the tension steel to balanced steel ratio, whose values at different concrete strengths are given in the paper.published_or_final_versio

Shear capacity of high-strength concrete beams with their point of inflection within the shear span

The shear strength of concrete does not increase in proportion with the concrete grade. Thus, when high-strength concrete is used in place of normal-strength concrete, the shear capacity of the structure could become critical. In the study presented, the effect of concrete strength on the shear capacity of concrete beams was investigated. As previous research on normal-strength concrete beams has shown that the presence of an inflection point within the shear span can significantly influence the shear capacity, particular effort was made to study this influence in the case of high-strength concrete beams. The results indicate that, as the concrete strength increases, the shear capacity of the beam also increases, but the shear capacity is proportional to the cube-root rather than the square-root of the concrete compressive strength. It is also revealed that the presence of an inflection point can increase the shear capacity by as much as 100%, regardless of whether normal-strength or high-strength concrete is used. Finally, the test results were analysed by comparing them with the predicted strength values calculated using the formulae given in the various codes and Aoyagi's equation.published_or_final_versio

What\u27s in it for me? Perspectives from Community Participants in an Inter-professional Service Learning Program

Purpose: This study assessed Interdisciplinary Family Health (IFH) Program participants‘ perceived health outcomes associated with program participation at the University of Florida. Background: Service-learning has emerged as a dynamic way in which students derive practical skills to address the needs of their community. Research has probed student perspectives but has seldom explored community feedback. The Interdisciplinary Family Health Program (IFH) is a mandatory Interprofessional service learning experience designed to foster collaborative teamwork across first year health professions students at UF. Students are assigned in interprofessional teams of four to improve a local volunteer family’s health over the course of four visits in one academic year. Description of Research: Data from twenty-one semi-structured telephone interviews were audio-recorded and transcribed to assess participants’ perceived health outcomes using a grounded theory approach. Emergent themes were conceptualized via selective coding and peer-reviewing. Results: All program participants reported positive health outcomes within a social support construct. Responses fell into four social support domains within a greater framework of bridging student-participant generations: informational support, emotional support, companionship support, and tangible support. Trends in social support domains observed were associated with participant SES. Participants with lower SES levels reported greater needs for health information and access, whereas participants with higher SES levels desired building social relationships with students. Conclusions: Tailoring IPE training to address specific social support domains and SES associations is an opportunity for enhanced participant experiences and perceived health outcomes. Educational planning can utilize social support domain-SES association findings as a guide for students to attune their efforts at improving the overall health outcomes of their target population. Learning Objectives and Related Conference Objectives: Participants will be able to describe qualitative methods of evaluating perceived patient health outcomes in assessing the effectiveness of the Interdisciplinary Family Health Program (Conference Objective 1). Participants will be able to communicate research findings regarding social support domain-SES approaches for enhanced educational programming and perceived patient health outcomes (Conference Objective 3)

Electronic Devices Based on Purified Carbon Nanotubes Grown By High Pressure Decomposition of Carbon Monoxide

The excellent properties of transistors, wires, and sensors made from single-walled carbon nanotubes (SWNTs) make them promising candidates for use in advanced nanoelectronic systems. Gas-phase growth procedures such as the high pressure decomposition of carbon monoxide (HiPCO) method yield large quantities of small diameter semiconducting SWNTs, which are ideal for use in nanoelectronic circuits. As-grown HiPCO material, however, commonly contains a large fraction of carbonaceous impurities that degrade properties of SWNT devices. Here we demonstrate a purification, deposition, and fabrication process that yields devices consisting of metallic and semiconducting nanotubes with electronic characteristics vastly superior to those of circuits made from raw HiPCO. Source-drain current measurements on the circuits as a function of temperature and backgate voltage are used to quantify the energy gap of semiconducting nanotubes in a field effect transistor geometry. This work demonstrates significant progress towards the goal of producing complex integrated circuits from bulk-grown SWNT material.Comment: 6 pages, 4 figures, to appear in Nature Material

Ionic transport in hybrid lead iodide perovskite solar cells

Solar cells based on organic–inorganic halide perovskites have recently shown rapidly rising power conversion efficiencies, but exhibit unusual behaviour such as current–voltage hysteresis and a low-frequency giant dielectric response. Ionic transport has been suggested to be an important factor contributing to these effects; however, the chemical origin of this transport and the mobile species are unclear. Here, the activation energies for ionic migration in methylammonium lead iodide (CH3NH3PbI3) are derived from first principles, and are compared with kinetic data extracted from the current–voltage response of a perovskite-based solar cell. We identify the microscopic transport mechanisms, and find facile vacancy-assisted migration of iodide ions with an activation energy of 0.6 eV, in good agreement with the kinetic measurements. The results of this combined computational and experimental study suggest that hybrid halide perovskites are mixed ionic–electronic conductors, a finding that has major implications for solar cell device architectures

A Nanoscale Design Approach for Enhancing the Li-Ion Conductivity of the Li₁₀GeP₂S₁₂Solid Electrolyte

\ua9 2022 American Chemical Society. The discovery of the lithium superionic conductor Li10GeP2S12 (LGPS) has led to significant research activity on solid electrolytes for high-performance solid-state batteries. Despite LGPS exhibiting a remarkably high room-temperature Li-ion conductivity, comparable to that of the liquid electrolytes used in current Li-ion batteries, nanoscale effects in this material have not been fully explored. Here, we predict that nanosizing of LGPS can be used to further enhance its Li-ion conductivity. By utilizing state-of-the-art nanoscale modeling techniques, our results reveal significant nanosizing effects with the Li-ion conductivity of LGPS increasing with decreasing particle volume. These features are due to a fundamental change from a primarily one-dimensional Li-ion conduction mechanism to a three-dimensional mechanism and major changes in the local structure. For the smallest nanometric particle size, the Li-ion conductivity at room temperature is three times higher than that of the bulk system. These findings reveal that nanosizing LGPS and related solid electrolytes could be an effective design approach to enhance their Li-ion conductivity

Prospects and retrospects of land use system through agroforestry practices in Meherpur district, Bangladesh

The study aims to explore the prospects and retrospects of land use system through agroforestry practices in Meherpur district, Bangladesh. It particularly focuses on some aspects of land uses of the study area like land use pattern, land ownership, choices of species for agroforestry, farmers’ perceptions towards agroforestry, status and prospects of agroforestry practices. This study was carried out by using mixed method followed by a semi-structure questionnaire. A total of 100 respondents were selected by using snowball purposive sampling method. The study revealed that agriculture was the major occupation (50%) of the selected respondents. Of the total land used by selected respondents, 21% land were used for agroforestry, 69% for agriculture and remaining 10% for homestead purposes. Most of the farmers (60%) were small landholders (1 to 5 acres) and 18% had lesser than 1 acre land. Among them 76% had their own land followed by 8% leased land and 16% both own and leased land. They preferred agroforestry in their homestead (92%), agricultural land (65%), water body (31%) and fallow land (18%). The farmers were practicing different types of agroforestry such as cropland, homestead and aquaculture with boundary plantation by mixing trees, agricultural crops and vegetables in their farmlands to receive diversified outcomes. A remarkable change in land use pattern was found after adopting agroforestry practices in this study area. Maximum respondents practiced agro-forestry in their homestead and croplands. Most of the land (67%) was used for agriculture cultivation while a very small amount of land was used as agroforestry in the study area.Int. J. Agril. Res. Innov. & Tech. 7 (2): 1-6, December, 201

Estimation of loss due to post harvest diseases of potato in markets of different districts in Bangladesh

The storage diseases of potato at Mymensingh, Rajshahi and Dhaka town were surveyed to estimate the loss in potato due to storage diseases. In Mymensingh district, the survey revealed that 3.95, 0.91 and 0.69% of tubers were affected with soft rot, dry rot and scab, respectively. Among the cultivars, maximum loss within the three months namely July, August and September were found in cultivar Cardinal (5.55%), where losses were caused by soft rot (3.97%), dry rot (0.88%) and scab (0.70%). In Rajshahi district, the survey revealed that 3.73, 0.99 and 0.85% of tubers were affected with soft rot, dry rot and scab, respectively. Among the cultivars, maximum loss within the three months were found in Cardinal (5.55%) having soft rot (3.58%), dry rot (1.06%) and scab (0.96%). In Dhaka district, the survey revealed that 3.27, 0.96 and 0.81% of tubers were affected with soft rot and dry rot. Among the cultivars, maximum loss within the three months was found in Diamant (5.55%) due to soft rot (2.49%), dry rot (1.05%) and scab (0.97%). Loss estimated in potato was 5.84, 5.54 and 5.25%, respectively in the months of July, August and September at Mymensingh district. Similarly, in Rajshahi district, it was 5.85, 5.58 and 5.28%, respectively in the month of July, August and September. Again in Dhaka district, it was 5.58, 4.96 and 4.55%, respectively in the months of July, August and September. The study revealed the fact that potatoes were subjected to different diseases in the markets of Bangladesh.Key words: Potato, storage diseases, months, loss, Bangladesh

Differential livelihood adaptation to social-ecological change in coastal Bangladesh

Social-ecological changes, brought about by the rapid growth of the aquaculture industry and the increased occurrence of climatic stressors, have significantly affected the livelihoods of coastal communities in Asian mega-deltas. This paper explores the livelihood adaptation responses of households of different wealth classes, the heterogeneous adaptation opportunities, barriers and limits (OBLs) faced by these households and the dynamic ways in which these factors interact to enhance or impede adaptive capacities. A mixed methods approach was used to collect empirical evidence from two villages in coastal Bangladesh. Findings reveal that households’ adaptive capacities largely depend on their wealth status, which not only determine their availability of productive resources, but also empower them to navigate social-ecological change in desirable ways. Households operate within a shared response space, which is shaped by the broader socio-economic and political landscape, as well as their previous decisions that can lock them in to particular pathways. While an adaptive response may be effective for one social group, it may cause negative externalities that can undermine the adaptation options and outcomes of another group. Adaptation OBLs interact in complex ways; the extent to which these OBLs affect different households depend on the specific livelihood activities being considered and the differential values and interests they hold. To ensure more equitable and environmentally sustainable livelihoods in future, policies and programs should aim to expand households’ adaptation space by accounting for the heterogeneous needs and complex interdependencies between response processes of different groups

Biomedical and biophysical limits to mathematical modeling of pulmonary system mechanics: a scoping review on aerosol and drug delivery.

Undoubtedly, the construction of the biomechanical geometry systems with the help of computer tomography (CT) and magnetic resonance imaging (MRI) has made a significant advancement in studying in vitro numerical models as accurately as possible. However, some simplifying assumptions in the computational studies of the respiratory system have caused errors and deviations from the in vivo actual state. The most important of these hypotheses is how to generate volume from the point cloud exported from CT or MRI images, not paying attention to the wall thickness and its effect in computational fluid dynamic method, statistical logic of aerosol trap in software; and most importantly, the viscoelastic effect of respiratory tract wall in living tissue pointed in the fluid-structure interaction method. So that applying the viscoelastic dynamic mesh effect in the form of the moving deforming mesh can be very effective in achieving more appropriate response quality. Also, changing the volume fraction of the pulmonary extracellular matrix constituents leads to changes in elastic modulus (storage modulus) and the viscous modulus (loss modulus) of lung tissue. Therefore, in the biomedical computational methods where the model wall is considered flexible, the viscoelastic properties of the texture must be considered correctly