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Mix design strategies for 3D printable bio-based cementitious composites using rice husk particles as multifunctional aggregates

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JOURNAL OF BUILDING ENGINEERING 2025年 100卷

作者： Tinoco, Matheus P. Cavalcante, Tiago C. de Andrade, Luiza D. de Araujo, Olga M. O. Lopes, Ricardo Tadeu Toledo Filho, Romildo D. Reales, Oscar A. Mendoza Univ Fed Rio de Janeiro Civil Engn Program BR-21941611 Rio De Janeiro RJ Brazil Univ Fed Rio de Janeiro Fac Architecture & Urbanism BR-21941901 Rio De Janeiro RJ Brazil Univ Fed Rio De Janeiro Nucl Engn Program Nucl Instrumentat Lab BR-21941611 Rio De Janeiro RJ Brazil

This work compares two mix design strategies for 3D printable cementitious composites using rice husk particles as multifunctional aggregates. The first strategy involves directly replacing sand with rice husk while keeping the cement paste volume constant. The second strategy introduces rice husk as an extra component, thereby increasing the solids content while maintaining a constant sand-to-cement ratio. Different volume fractions of rice husk (10 %, 15 %, 20 %, and 25 %) were used. Replacing natural sand with 15 % bio-aggregates leads to a 53 % decrease in yield stress and a 62 % decrease in structuration rate, due to the lubricating effect of pre-wetted bioaggregates and a decrease in system interlock. Adding rice husk as extra component, however, increases both yield stress and structuration rate, which is related to the reduced paste volume and increase in internal friction. With 25 % rice husk, the initial yield stress increases from 1.21 kPa to 5.55 kPa, and the structuration rate increases from 26.9 Pa/min to 105.2 Pa/min. The second strategy effectively improved buildability and reduced cement consumption, making it the most suitable choice for producing printable mixtures. Mechanical tests indicate that rice husk has limited effect on anisotropy and interlayer bond adhesion. However, at higher fractions, increased porosity and particle debonding at interfaces pose new challenges for enhancing composite performance. The results highlight the potential rice husk as a multifunctional aggregate in 3D-printed cementitious composites, providing insights for the development of sustainable construction materials with optimized fresh and mechanical properties.

关键词： 3D concrete printing Bio-aggregates Water absorption Fresh properties Mechanical properties Interlayer bond adhesion X-ray microtomography

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Semi-dry natural carbonation at different relative humidities: Degree of carbonation and reaction kinetics of calcium hydrates in cement paste

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CEMENT AND CONCRETE RESEARCH 2025年 189卷

作者： Saeki, Naohiko Kurihara, Ryo Ohkubo, Takahiro Teramoto, Atsushi Suda, Yuya Kitagaki, Ryoma Maruyama, Ippei Univ Tokyo Grad Sch Engn Dept Architecture Tokyo 1138656 Japan Chiba Univ Grad Sch Engn Dept Appl Chem & Biotechnol Chiba 2638522 Japan Hiroshima Univ Grad Sch Adv Sci & Engn Dept Architecture Hiroshima 7398527 Japan Univ Ryukyus Fac Engn Civil Engn Program Nishihara Okinawa 9030213 Japan Hokkaido Univ Grad Sch Engn Div Human Environm Syst Sapporo 0608628 Japan Nagoya Univ Grad Sch Environm Studies Dept Environm Engn & Architecture Nagoya 4648603 Japan

This study investigated semi-dry carbonation at different relative humidities (RH) under atmospheric CO2 concentrations to determine the effect of RH on the degree of carbonation (DoC) and reaction rates. The carbonation kinetics of each calcium-containing hydrate exhibited an initial rapid chemical-reaction-limited stage, followed by a significantly slower stage. DoC values plateaued after 200 days of carbonation, reaching 78 % at 95 % RH and 34 % at 33 % RH, aligning with EN 16757 values for sheltered outdoor and indoor environments, respectively. When the samples reached a stable DoC at a given RH, further carbonation occurred upon exposure to higher RH, implying that the DoC was governed by the highest RH to which the samples had been exposed. The phase assemblage was also affected, approaching thermodynamic equilibrium at higher RH but deviating at lower RH due to the formation of local equilibria and the presence of metastable phases.

关键词： Degree of carbonation Kinetics Phase assemblage Relative humidity

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Chitosan-based hydrogel incorporating mesoporous silica/zinc oxide nanoparticles with controlled swelling and potent antibacterial activity

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INTERNATIONAL JOURNAL OF POLYMERIC MATERIALS AND POLYMERIC BIOMATERIALS 2025年第6期74卷 465-473页

作者： Aykac, Ahmet Ok, Izel Bakay, Emel Topaloglu, Nermin Izmir Katip Celebi Univ Dept Engn Sci Izmir Turkiye Izmir Katip Celebi Univ Nanosci & Nanotechnol Grad Program Izmir Turkiye Izmir Katip Celebi Univ Biomed Technol Grad Program Izmir Turkiye Abo Akad Univ Dept Sci & Engn Turku Finland Izmir Katip Celebi Univ Fac Engn & Architecture Dept Biomed Engn Izmir Turkiye

Staphylococcus aureus (S. aureus) is a notable causative agent of bacterial infections known for its development of antibiotic resistance over time. In response, hydrogels augmented with antibacterial nanoparticles (NPs) and controllable swelling properties have emerged as promising alternatives. In the study, a novel chitosan (CS)-based hydrogel was prepared by combining CS as a main component, zinc oxide NPs (ZnO NPs) as an antibacterial agent, and mesoporous silica NPs (MSN) as the swelling control material. Comprehensive characterization of the prepared novel hydrogels were carried out by dynamic light scattering (DLS), zeta potential (zeta-potential), Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microcopy (SEM), and X-ray diffraction (XRD). The ZnO/MSN/CS-based hydrogel exhibited superior swelling, precisely controllable swelling, and potent antibacterial activity against S. aureus. These hybrid CS-based hydrogels, incorporating both ZnO NPs and MSN, exhibit significant potential as agents for combating antibiotic resistance, offering an alternative strategy to mitigate reliance on conventional antibiotics.

关键词： Antibacterial activity chitosan hydrogel mesoporous silica nanoparticles zinc oxide nanoparticles

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Coherence of the frequency-difference autoproduct deduced from high-frequency acoustic fields scattered from a rough sea surface

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024年第1期156卷 600-609页

作者： Joslyn, Nicholas J. Dahl, Peter H. Dowling, David R. Univ Michigan Appl Phys Program Ann Arbor MI 48105 USA Univ Washington Appl Phys Lab Seattle WA 98105 USA Univ Michigan Dept Naval Architecture & Marine Engn Ann Arbor MI 48105 USA

The prevalence of random scattering from a rough ocean surface increases with increasing chi = kh cos theta , where k is the acoustic wavenumber, h is the root-mean-square surface height, and theta is the incidence angle. Generally, when chi >> 1, coherence between incident and surface-scattered fields is lost. However, such coherence may be recovered when chi >> 1 by considering the frequency-difference autoproduct of the surface-scattered field, a quadratic product of complex fields at nearby frequencies. Herein, the autoproduct's coherent reflection coefficient for chi > 20 is determined from surface-scattered sound fields obtained from 50 independent realizations of the rough ocean surface measured in pelagic waters off the coast of California in January 1992. The recordings were made with a source at a depth of 147 m that broadcasted 30 and 40 kHz signals to a single receiver 576 m away at depth of 66 m. An analytic formula for the coherent reflection coefficient of the frequency-difference autoproduct, based on the Kirchhoff approximation and a Gaussian surface autocorrelation function, compares favorably with measurements. Improved agreement with the single-receiver measurements is possible via a minor adjustment to the surface autocorrelation length. The adjustment identified here matches that determined previously from horizontal spatial coherence estimates utilizing the experiment's eight-element receiving array.

关键词： Reflection

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Development of Inkjet-Printed PEDOT:PSS-Based Organic Electrochemical Transistor (OECT) for Biopotential Amplification

Development of Inkjet-Printed PEDOT:PSS-Based Organic Electr...

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45th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC)

作者： Khoury, Fadi C. Saleh, Sahera A. Habli, Zeina S. Khraiche, Massoud L. Amer Univ Beirut Maroun Semaan Fac Engn & Architecture Biomed Engn Program Neural Engn & Nanobiosensors Grp Beirut Lebanon

ISBN: (纸本)9798350324471

With the ever-increasing need for miniaturized and biocompatible devices for physiological recordings, high signal fidelity and ease of fabrication are key to achieve reliable data collection. This calls for the development of active recording devices such as Organic Electrochemical Transistors (OECTs) which, compared to passive electrodes, offer local amplification. In this work, we built PEDOT:PSS based OECTs using novel inkjet printing technology, achieving a transconductance of 75 mS. The device was later used to amplify arbitrary signals simulating in vivo recordings. Gate voltage offset manipulation offered a range of current peak-to-peak amplitudes. Additionally, we demonstrate a simple circuit for voltage readings, where another resistor-dependent characterization involving voltage source and drain voltage is performed. At ideal operating point and when using a 220 O resistor, a gain of 14.5 is achieved.

关键词： Resistors

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EFFICIENCY OF SOUND ENERGY DECAY ANALYSIS IN AUDITORIA 11

EFFICIENCY OF SOUND ENERGY DECAY ANALYSIS IN AUDITORIA

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11th International Conference on Auditorium Acoustics

作者： Xiang, N. Sü Gül, Z. Graduate Program in Architectural Acoustics Rensselaer Polytechnic Institute United States Department of Architecture Bilkent University Turkey

ISBN: (纸本)9781906913458

Recent auditorium acoustics practice has included coupled-volume systems in several performing arts venues. This has stimulated research activities on acoustics in the coupled-volume systems. Based on experimentally measured room impulse responses acquired from existing auditoria, and several historically significant worship spaces, this paper addresses the challenges of analysing single-slope and multiple-slope sound energy decays often encountered in the experimentally measured room impulse responses in these venues. The analysis engages a parametric model of Schroeder decay functions, that decomposes the Schroeder decay data into single or multiple exponential decays along with a noise term. The model has been well validated using many experimental data. Several advanced analysis methods based on the decay model, such as nonlinear regressions, Bayesian probabilistic inference, and artificial neural networks have emerged to cope with analysis challenges raised in auditorium acoustics practice. This paper discusses conditions of implementing Schroeder integration for a higher efficiency of the numerical analysis and clarifies some unreasonable expectations/interpretations of Schroeder decay data. © 2023 Institute of Acoustics. All rights reserved.

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Inkjet-Printed, Flexible Organic Electrochemical Transistors for High-Performance Electrocorticography Recordings

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ACS APPLIED MATERIALS & INTERFACES 2024年第41期16卷 55045-55055页

作者： Khoury, Fadi Saleh, Sahera Badawe, Heba Obeid, Makram Khraiche, Massoud Amer Univ Beirut Maroun Semaan Fac Engn & Architecture Biomed Engn Program Neural Engn & Nanobiosensors Grp Beirut 11072020 Lebanon Indiana Univ Sch Med Stark Neurosci Res Inst Dept Neurol Indianapolis IN 46202 USA

Organic electrochemical transistors (OECTs) have emerged as powerful tools for biosignal amplification, including electrocorticography (ECoG). However, their widespread application has been limited by the complexities associated with existing fabrication techniques, restricting accessibility and scalability. Here, we introduce a novel all-planar, all-printed high-performance OECT device that significantly enhances the accuracy and sensitivity of ECoG recordings. Achieved through an innovative three-step drop-on-demand inkjet printing process on flexible substrates, our device offers a rapid response time of 0.5 ms, a compact channel area of 1950 mu m2, and is characterized by a transconductance of 11 mS. This process not only simplifies integration but also reduces costs. Our optimized in-plane gate voltage control facilitates operation at peak transconductance, which elevates the signal-to-noise ratio (SNR) by up to 133%. In vivo evaluations in a rat model of seizure demonstrate the device's performance in recording distinct electrographic phases, surpassing the capabilities of PEDOT:PSS-coated gold-based ultralow impedance passive electrodes, achieving a high SNR of 48 db. Our results underscore the potential of Inkjet-printed OECTs in advancing the accessibility and accuracy of diagnostic tools that could enhance patient care by facilitating timely detection of neurological conditions.

关键词： amplification electrocorticography neuralinterface Organic Electrochemical Transistor (OECT) seizure

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Coherent reflection recovery in scattering from the ocean surface using the frequency-difference autoproduct^a)

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024年第3期155卷 1868-1880页

作者： Joslyn, Nicholas J. Dahl, Peter H. Dowling, David R. Univ Michigan Appl Phys Program Ann Arbor MI 48109 USA Univ Washington Appl Phys Lab Seattle WA 98105 USA Univ Michigan Dept Naval Architecture & Marine Engn Ann Arbor MI 48109 USA

The coherence of rough sea-surface-scattered acoustic fields decreases with increasing frequency. The frequency-difference autoproduct, a quadratic product of acoustic fields at nearby frequencies, mimics a genuine field at the difference frequency. In rough-surface scattering, the autoproduct's lower effective frequency decreases the apparent surface roughness, restoring coherent reflection. Herein, the recovery of coherent reflection in sea surface scattering via the frequency-difference autoproduct is examined for data collected off the coast of New Jersey during the Shallow Water '06 (SW06) experiment. An acoustic source at depth 40 m and receiver at depth 24.3 m and range 200 m interrogated 160 independent realizations of the ocean surface. The root mean square surface height h was 0.167 m, and broadcast frequencies were 14-20 kHz, so that 2.5 <= k h cos theta <= 3.7 for acoustic wavenumber k and incidence angle theta. Measured autoproducts, constructed from scattered constituent fields, show significant coherent reflection at sufficiently low difference frequencies. Theoretical results, using the Kirchhoff approximation and a non-analytic surface autocorrelation function, agree with experimental findings. The match is improved using a numerical strategy, exploiting the relationship between autoproduct-based coherence recovery, the ocean-surface autocorrelation function, and the ocean-surface height spectrum. Error bars computed from Monte Carlo scattering simulations support the validity of the measured coherence recovery. (c) 2024 Acoustical Society of America.

关键词： Surface roughness

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Navigating the definition of urban flooding: a conceptual and systematic review of the literature

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WATER SCIENCE AND TECHNOLOGY 2024年第10期90卷 2796-2812页

作者： Alves, Priscila Barros Ramalho Amanguah, Ebenezer Mcnally, Devin Espinoza, Maria Ghaedi, Hamed Reilly, Allison Hendricks, Marccus Univ Maryland Sch Architecture Planning & Preservat Stormwater Infrastruct Resilience & Justice SIRJ L College Pk MD 20742 USA Univ Maryland A James Clark Sch Engn Civil & Environm Engn Program College Pk MD USA

Urban flooding is a significant global challenge, posing risks to urban planners, policymakers, and communities. This paper reviews the literature to analyze how urban flooding is defined across scientific disciplines. Our objectives are to uncover the elements used to define urban flooding and evaluate how these elements can impact future research and practice. A key difficulty is the lack of a consistent, comprehensive definition that captures both physical and social dimensions of urban flooding. Current definitions often focus solely on physical aspects (e.g., rainfall, infrastructure) or social impacts, rarely integrating both. This fragmentation hinders effective flood risk management and interdisciplinary collaboration. Our contribution is a multifaceted definition incorporating spatial and social concerns, including water origins, built environment characteristics, and local community aspects. We introduce the "Urban Water Transect" concept to illustrate the continuum of flood risk across urban zones, addressing a gap in the literature. The analysis reveals that many papers discuss flooding causes without providing an explicit definition. Urban flooding is predominantly defined based on water source, imperviousness, and drainage infrastructure. Future research should adopt an interdisciplinary perspective considering both physical and social aspects, potentially transforming urban flood risk management.

关键词： imperviousness infrastructure pluvial social aspects urban flooding

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How and why do people with disabilities use app-based ridehailing?

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CASE STUDIES ON TRANSPORT POLICY 2022年第4期10卷 2556-2562页

作者： Cochran, Abigail L. Univ Nebraska Coll Architecture Community & Reg Planning Program 217 Architecture Hall400 Stadium Dr Lincoln NE 68588 USA

Over 40 million people in the United States live with disabilities. Yet, relatively little is known about the travel behavior of people with disabilities, particularly as it relates to their use of emerging services like app-based ridehailing provided by transportation network companies (TNCs), such as Uber and Lyft. Analyzing in-depth interviews with 32 individuals with disabilities living in the San Francisco Bay Area, I find that TNC use depends on respondents' prior experience using transportation and smartphones. Older adults and those who acquired their disabilities relatively recently had difficulty using app-based ridehailing due to perceived and experienced challenges hailing a ride, finding the vehicle, and getting to their destination independently. Younger respondents and those who had lived with their disabilities longer perceived ridehailing to be reliable and convenient, and found it relatively more affordable than taxis. They liked having app-based ridehailing as an option. This was also true among respondents who used motorized wheelchairs, but they said that the availability and quality of wheelchair-accessible ridehailing services were lacking. Subsidizing app-based ridehailing may encourage greater use of these services among some people with disabilities. However, this approach and new policies aimed at improving wheelchair-accessible ridehailing services do not address expressed barriers to ridehailing use-especially among older adults with disabilities. Other interventions, such as training programs for ridehailing drivers as well as potential riders, might help address some of these barriers.

关键词： Disability Qualitative research Ridehailing Transportation network companies (TNCs) Travel behavior

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