Passive Materials Research Articles

Passive dimming phase change material inspired by polymer hydrogels

As a new concept of smart materials, passive dimming phase change materials (PDPCMs) have potential in the field of energy-efficient buildings due to ultra-high energy utilization efficiency. Novel PDPCMs materials are reported by simulating the microstructure of high light transmittance polymer hydrogels. The self-prepared composite coordinates the inherent contradiction between anti liquid leakage, optical transmittance switching, and thermal storage density. There is an interaction between the hydroxyl groups (–OH) of MA and the ester groups (–COOR) of polybutylmethacrylate (PBMA), resulting in the PBMA/MA with a VMA/VPBMA volume ratio of 6:5 exhibiting good resistance to liquid leakage even when stretched to about 400 % at 60 °C. Based on the good compatibility and well-matched refractive index between MA and PBMA framework materials, the visible light transmittance of as-prepared PDPCMs has increased from 0.1 % at 30 °C to 89.0 % at 60 °C. The as-prepared composite also exhibits a good latent heat-storage capability with satisfactory phase-change enthalpies of over 113 J g−1. The as-prepared PDPCMs eliminate the spatial positional differences between photo-thermal conversion and thermal energy absorption, without considering the thermal conductivity of PDPCMs. The photo-thermal conversion efficiency can be increased by introducing well-matched color changing ink (CCI), significantly improving energy utilization efficiency. On the other hand, energy-saving doors/windows containing PBMA/MA composite materials allow sunlight to spread indoors due to the high transmittance (89.0 %) at high temperatures. The new design concept makes passive dimming composite materials suitable for high latitude areas.

Enhanced co-design and evaluation of a collective robotic construction system for the assembly of large-scale in-plane timber structures

Collective robotic construction (CRC) is an emerging approach to construction automation based on the collaboration among teams of small mobile robots. This paper enhances an existing modular CRC system, showcasing its capability to assemble full-scale in-plane timber structures. Utilizing strategies of co-design, the robotic actuators were updated to accommodate material tolerance in the passive building material, timber struts, which they use for locomotion and assemble into structures. A custom effector was also developed to establish architecturally relevant, structural connections between struts. The enhancements address two major challenges in CRC system development: material tolerance and connections. To showcase these research findings and compare with other construction automation systems, a reinforced slab structure was assembled. With a building envelop of 0.485 m3, this is one of the largest structures assembled by a CRC system. As such, the work highlights the potential applicability of CRC in real-world architectural projects.

Semiconducting Sc2O3–ZnO nanostructures: Sustainably synthesized efficient material for electro-catalysis, energy storage, and passivation in ambient perovskite solar cells

This work presents the first account of the transformed sustainable production in conjugation with the microwave processing of the scandium oxide (Sc2O3) and zinc oxide (ZnO) forming Sc2O3–ZnO nanostructure. Upon nanocomposite formation, the band gap energy was alleviated to 3.87 eV from 5.8 eV Sc2O3–ZnO nanostructure was characterized with the cubic and hexagonal geometry possessing an average crystallite size of 69.21 nm. The developed nanomaterial exhibited superior catalytic potential towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with the minor overpotential of 180 and 125 mV, respectively. The designed electrode remained unscathed electrochemically for 1500 min in electrolyte environment. Also, this material expressed exquisite potential for charge storage with the specific capacitance of 589 F g−1 in NaCl electrolyte showing candidacy for supercapacitor application. Furthermore, the passivation role of these nanomaterials improved the photovoltaic efficiency of the perovskite solar cell, which achieved 11.41% of the power conversion efficiency in addition to improved fill factor. Sc2O3–ZnO nanostructure is a sustainable and eco-friendly material with the efficient output in diverse energy systems. Therefore, it possesses greater candidacy for adoption in terms of commercialization replacing costly materials.

Investigation on radiation attenuation properties of natural stone samples traded in Turkey

Although radioprotection is globally regulated for high radiation exposure, formal guidelines concerning natural radiation exposure that causes stochastic radiation effects have not been established. The commonly used absorbers lead, tungsten and bismuth are not appropriate for the radioprotection of the public. The primary barrier against natural radiation is the structural components of buildings, where humans spend approximately 80 % of their lifetime. Natural stones are secondary materials, which are applied to walls and floors as coating. This study focuses on the radiation shielding properties of natural stones. Herein, the samples of marble, granite and sedimentary rock traded in Turkey were examined to determine whether they can serve as passive or alternative radioprotection materials. Notable gamma absorption rates were obtained when an intense gamma source with an energy of 662 keV was used. The calculated mass attenuation coefficients were comparable with those of copper and aluminium. The mean mass attenuation coefficient was 0.082 cm2/g for marbles and granites and 0.080 cm2/g for sedimentary rocks. Considering the stochastic effects, the use of the natural stones as construction materials is anticipated to significantly reduce the natural radiation level in inhabitable regions. Furthermore, natural stones can be used in clinics as secondary radiation shields against low-energy gamma and x-rays.

Interviews With Lay Caregivers About Their Experiences Supporting Patients Throughout Kidney Transplantation.

Introduction: Lay caregivers provide essential support to patients throughout the kidney transplant process, pretransplant through discharge. Sparse data exists about kidney transplant caregiver experience and facilitators of caregiver engagement. The aim of this study was to explore and describe lay caregivers' accounts of supporting a patient before and early after kidney transplantation. Methods: Caregivers of recent kidney transplant recipients were individually interviewed about their experiences, coping strategies, and perspectives of center-specific support approaches for patients and caregivers in a single transplant center. Results: Inductive content analysis of transcribed interviews with 23 caregivers revealed 6 domain areas: visit preparation, initial evaluation, caregiver role discussion, exposure to support resources, transplant preparedness, and coping styles. Caregivers used and appreciated information offered by the transplant center, including materials directed to the patient. They recommended repeating information, online access, and adding video to complement print resources. They valued and requested information directed to them, both within passive materials and communication with providers. Social network interactions were helpful for practical, emotional, and informational support. Support group reminders and connection pathways to peers were suggested for both patients and caregivers. Conclusion: Findings highlight steps that can be taken by transplant centers and may stimulate caregiver engagement. Featuring caregiver-focused information and communication more prominently may support caregivers to improve patient progress in navigating kidney transplantation.

In situ differential atomic force microscopy (AFM) measurement for ultra-thin Thiol SAM patterns by area-selective deposition technique

Developing novel characterization methods is crucial to enhancing the accuracy and precision of measurements in semiconductor ultrathin films. By combining "bottom-up" and "top-down" patterning techniques, we successfully fabricated five uniform alkyl thiol-derived self-assembled monolayer (SAM) patterns. Employing the innovative in situ differential Atomic Force Microscopy (AFM) Measurement, we analyzed the thickness, morphology, and mechanical properties of the thiol films. This method greatly reduced errors caused by uneven substrates, resulting in more precise measurements compared to large-area measurements. It is shown that as the thiol chain length increased, the variation in SAM film thickness aligned consistently with the thickness of a single Atomic Layer Deposition (ALD) cycle, and the surface roughness of the SAM surface mirrored that of ALD. Consequently, the experiment affirms the effectiveness of the SAM film in simulating ALD, providing validation for the precision and feasibility of the in situ differential results. Furthermore, adhesion measurement results revealed a diminishing passivation effect of SAM as the chain length increased. This suggests that an appropriate SAM could be selected as a passivation material through real-time monitoring of the mechanical properties of the mask surface during the Area-Selective Deposition (ASD) process.

Mechanical and micro-structural aspects of admixture stabilized rock sludge dust

The Rock Sludge Dust (RSD) is a by-product generated during the cutting and polishing of stone slabs obtained from rock blocks in the rock processing industry. Currently, only a minimal amount of RSD is being used, while larger quantities are being stored within the industrial vicinity. In its dry state, this fine sludge dust is susceptible to rising even under mild winds, causing severe health and environmental concerns. The previous attempts by a few researchers to utilize this industrial waste were confined to brick making, cement manufacturing and concrete making within the projected utilization of up to 20%; and even to that extent, the field performance and confirmatory studies are lacking. In this endeavor, an attempt is made to study the possible use of non-reactive RSD as a passive bulk material within the stabilized matrix using other materials such as locally available clay soil, lime, and pozzolan (fly ash). The present study revealed that the addition of 10% local clay soil to RSD could alter its dust texture to natural soil texture so that its handling and transportation become convenient without dust nuisance. Further, the addition of 5% lime and 10% fly ash could impart UCS values ranging from 3.20 MPa to 5.88 MPa, thus making it a suitable material for the construction of low-volume roads. The XRD and SEM analyses of the favorable mix combinations arrived at based on the tests on trial mixes indicate the formation of cementitious minerals and gels. These findings enable the concerned construction industry to utilize the non-reactive RSD for gainful purposes, alleviating environmental issues and making the approach sustainable and eco-friendly.

Characterization of Thin AlN/Ag/AlN-Reflector Stacks on Glass Substrates for MEMS Applications

Thin metal layers such as silver (Ag) are being utilized for various optical and plasmonic applications as well as for electrical purposes, e.g., as transparent electrodes in display devices or solar cells. This paper focuses on optical MEMS applications such as the Fabry–Pérot interferometer (FPI). Within such filters, reflector materials such as distributed Bragg reflectors (DBRs) or subwavelength gratings (SWGs) have been widely used so far, whereas metallic thin films (MTFs) were limited in application due to their comparatively higher absorption. In this paper, thin sputtered Ag layers with thicknesses of 20, 40 and 60 nm on glass substrates have been investigated, and it is shown that the absorption is very low in the visible spectral range (VIS) and increases only in near-infrared (NIR) with increasing wavelength. Thus, we consider Ag-thin layers to be an interesting reflector material at least for the VIS range, which can be easily fabricated and integrated. However, Ag is not inert and stable when exposed to the atmosphere. Hence, it needs a passivation material. For this purpose, AlN has been chosen in this contribution, which can be deposited by sputtering as well. In this contribution, we have chosen thin AlN layers for this purpose, which can also be deposited by sputtering. Thus, various AlN/Ag/AlN-reflector stacks were created and patterned by lift-off technology preferably. The fabricated reflectors were characterized with respect to adhesion, stress, cohesion, homogeneity, and most importantly, their optical properties. It was found that the thickness of the AlN can be used to adjust the reflectance–transmittance ratio in the VIS range, and influences the adsorption in the NIR range as well. Based on the measured values of the reflectors with 40 nm Ag, an exemplary transmission filter characteristics has been predicted for a wavelength range from 400 to 800 nm. Both the maximum transmittance and the full width at half maximum (FWHM) can be tuned by variation of the AlN thickness from 20 to 60 nm.

Research progress of piezoelectric polymer PVDF in sound absorption technology

Owing to its impedance properties and piezoelectric effect, the piezoelectric polymer polyvinylidene fluoride (PVDF) finds application in the field of noise control. Traditional sound-absorbing materials have gradually fallen short of the demands of sound-absorbing functionality and environmental adaptability in today’s increasingly acute noise pollution environment. When PVDF is added to sound absorption, materials or structures have an additional loss path for the conversion of sound energy to electric energy. This helps to increase the low-frequency sound absorption band and improve low-frequency sound absorption performance. Through the action of viscosity, friction, relaxation, piezoelectric effect, and dielectric loss, the sound energy in the passive sound-absorbing material containing PVDF is transformed into energy dissipation in the form of heat energy, electric energy, and so on under the matching of PVDF low impedance. In active control, secondary sound and force sources can be supplied by PVDF-based transducers and actuators to reduce noise. This paper first provides an overview of the piezoelectric characteristics of β-phase PVDF and its optimization techniques. It then goes on to discuss the use of PVDF in passive sound-absorbing materials, active controls, and hybrid sound absorption systems. Finally, it summarizes the benefits, issues that still need to be resolved, and future directions for these three noise reduction techniques.

Microstructure and ablation behaviour of C/C-SiC-ZrC-Cu composites prepared by reactive melt infiltration

To satisfy the requirements for the new generation solid rocket motors on high ablation-resistant throat materials, an idea that merges passive and active thermal protection together was applied to modify carbon/carbon composites. In this study, SiC and ZrC were used as passive thermal protection materials along with the active thermal protection material Cu to modify C/C composites. C/C-SiC-ZrC-Cu composites were prepared by two-step reactive melt infiltration, which involved the infiltration of Si/Zr followed by Cu/Ti. The Cu content of the C/C-SiC-ZrC composites was controlled by controlling the open porosity of the porous C/C-SiC-ZrC composites. Microstructure, composition and ablation resistance of the C/C-SiC-ZrC-Cu composites were investigated. The results showed that the composites with high Cu content and density exhibited excellent short-term ablation resistance under the 42 kW plasma flame, with a negative linear ablation rate after 20 s of ablation. The active heat dissipation of Cu during the ablation process results in a significant reduction of the thermal response temperature on the composite surface. Moreover, the generated Si-Ti-Zr-O layer could form an effective barrier to protect the matrix.

Graphite from Dead Li‐Ion Batteries: A “Powerful” Additive for Fabrication of High‐Performance Li‐Ion Capacitors

AbstractLithium‐ion capacitors (LICs) are considered a promising next‐generation energy storage system with high energy density and power capability. The conductive additive is a passive and indispensable material in deciding the electrochemical performance of an energy storage device during high current charging and discharging processes. The incorporation of a suitable conductive additive into the layers of an electrode improves electronic conductivity. It reduces the internal resistance and polarization of the electrode resulting in the enhanced performance of the charge‐storage system. Herein, recovered graphite (RG) is reported from dead Li‐ion batteries as an excellent conductive additive that can improve the electronic conductivity of the electrode material. Compared with commercial conductive additive acetylene black (AB), the TiO2 anode material with 5% RG delivered a high discharge capacity of 163 mAh g−1 at a current rate of 0.15 A g−1 with a coulombic efficiency of ≈99% after 500 cycles in half‐cell assembly. The fabricated AC/TiO2@5%RG LIC displays an excellent electrochemical performance with a maximum energy density of ≈50 Wh kg−1 at a current density of 0.15 A g−1. Notably, the LIC rendered promising performance at different temperature conditions (0, 10, 25, and 50 °C).

Building the Future with Earth – Herbarium CSEB as a Modern Self-Insulative, Eco-Friendly Material

Many types of analysis were undertaken in sustainability and passive energy, Reduction in Carbon emission and cost-effective style in summer cooling, it’s like rather than the usage of AC these days because of climate weather modification even this year and in coming years I needed to visualize whether or not the CSEB material is actually replacing AC system for a sustainable future. the rise of a movement against non-eco-friendly practices nowadays has woke up us to adapt to and incorporate practices that are pro-earth. we've got realized that the smaller steps taken nowadays, have a larger impact on our tomorrow. green practices within the housing industry will contribute towards a more robust and greener tomorrow. Construction using CSEBs is one in every of the various ways in which we are able to resort cut back the negative impact on mother earth. In this study, the effect of bulk viscosity and cement content on the thermal conductivity of cement- stabilized earth block CSEB is delved . Experimental results show that thermal conductivity increases with bulk viscosity. Changing the cement content slightly changes the thermal conductivity of CSEB at a specific bulk viscosity. No clear direct relationship was observed between thermal conductivity and cement content in CSEB. still, the CSEB compressive strength increased significantly with cement addition. Also, the compressive strength of CSEB increases as the cement content increases. CSEB shows pledge in earthen structures due to its increased compressive strength and reduced thermal conductivity. Keyword: Eco-friendly, Herbarium CSEB, Effective thermal comfort, Indoor thermal conductivity, passive material making, Herbs – Henna, Traditional techniques, Adobe earth blocks, Natural material.

Whipple’s Vision: Theology of the Land and Nineteenth-Century Episcopal Missions to Minnesota Native Americans

This article considers theologies of the land by examining the legacy of the nineteenth-century Episcopal bishop Henry Benjamin Whipple and his encounter with Minnesota’s Native American people. Using the work of Willie James Jennings as an interpretive lens, it argues that Whipple developed and implemented a theology in which land is (1) fundamentally separate from people, (2) passive physical material, (3) a resource for human productivity, and (4) an instrument for the formation of Christian and American identity. It shows how such a vision of the land has contributed to a destructive theology of displacement, conquest, wealth, and assimilation. It briefly proposes an alternative theology of the land in which land is (1) distinguishable but not separable from people, (2) differentiated and sacred, (3) a creature with value exceeding its productivity, and (4) a place for mutual formation of people and land through God’s power.

Heat dissipation performance research of battery modules based on composite phase change materials cooling and electrochemical thermal coupling model

In order to improve electric vehicle lithium-ion batteries (LIBs) performance and increase cycle life, it is crucial to design a reliable and efficient battery thermal management system (BTMS). Compared with other active battery cooling methods, passive phase change material (PCM) cooling has the advantages of simple structure, good temperature control uniformity, strong reliability, and no additional energy consumption. This article uses a series of experimental procedures to add expanded graphite to traditional paraffin wax PCM and obtain composite phase change materials (CPCM) with different mixing ratios. A control experiment is created to compare the cooling performance of the CPCM cooling with natural convection cooling, research shows that the cooling performance of CPCM can well meet the cooling demand which maximum temperature and maximum temperature difference of battery modules. In addition, to study the performance of thermal properties parameters related to CPCM, a COMSOL numerical calculation model of battery module based on CPCM cooling and electrochemical thermal coupling model is established. The effectiveness and accuracy of the model are verified through heat generation experiments at different rates (0.5 C, 1 C, 1.5 C), with a maximum temperature error of 1.6 K and an error accuracy of less than 0.6%. Subsequently, the performance of phase change temperature, thermal conductivity and phase change latent heat is studied and reasonable value ranges are obtained, which are 312 K∼318 K, 2.5 W /(m·K), and 175 J/g∼200 J/g, respectively.

Electron and photon energy calibration with the ATLAS detector using LHC Run 2 data

This paper presents the electron and photon energy calibration obtained with the ATLAS detector using 140 fb-1 of LHC proton-proton collision data recorded at √(s) = 13 TeV between 2015 and 2018. Methods for the measurement of electron and photon energies are outlined, along with the current knowledge of the passive material in front of the ATLAS electromagnetic calorimeter. The energy calibration steps are discussed in detail, with emphasis on the improvements introduced in this paper. The absolute energy scale is set using a large sample of Z-boson decays into electron-positron pairs, and its residual dependence on the electron energy is used for the first time to further constrain systematic uncertainties. The achieved calibration uncertainties are typically 0.05% for electrons from resonant Z-boson decays, 0.4% at E T ∼ 10 GeV, and 0.3% at E T ∼ 1 TeV; for photons at E T ∼ 60 GeV, they are 0.2% on average. This is more than twice as precise as the previous calibration. The new energy calibration is validated using J/ψ → ee and radiative Z-boson decays.

Chiral Standing Spin Waves and Unidirectional Waves of Odd Elastic Cylindrical Shells

Abstract Rotating waves can be observed in structures with periodic conditions, such as cylinders and spheres. Compared with traveling waves and standing waves, rotating waves have received less attention. In this paper, an odd elastic dynamic model of the cylindrical shells is established, and the dispersion relation, traveling waves, and standing waves are investigated. The non-Hermitian rotating waves and single-handedness chiral standing spin waves are reported, which are novel dynamic phenomenon caused by odd elastic effects. Waves generally cannot propagate in passive materials with vanishingly small elastic modulus. However, a unidirectional wave with the highest cut off frequency can occur in an odd elastic cylindrical shell with vanishingly small elastic modulus. For incompletely restrained end displacements, the odd elastic cylindrical shell can also generate a hybrid mode combining standing spin waves with unidirectional waves.

Enhancing Performance and Stability of Sn-Pb Perovskite Solar Cells with Oriented Phenyl-C61-Butyric Acid Methyl Ester Layer via High-Temperature Annealing.

Phenyl-C61-butyric acid methyl ester (PCBM) can be used as a passivation material in perovskite solar cells (PeSCs) in order to reduce the trap site of the perovskite. Here, we show that a thick PCBM layer can form a smoother surface on the SnO2 substrate, improving the grain size and reducing the microstrain of the perovskite. High-temperature annealing treatment of PCBM layer not only increases its solvent resistance to perovskite precursor or antisolvent, but also enhances its molecular alignment, resulting in improved conductivity as an electron transport layer. High-temperature annealed PCBM (HT-PCBM) effectively minimizes trap-assisted nonradiative recombination by reducing trap density in perovskite and improving the electrical properties at the interface between SnO2 and perovskite layers. This HT-PCBM process significantly enhances the performance of the PeSCs, including the open-circuit voltage (VOC) from 0.39 to 0.77 V, fill factor from 52% to 65%, and power conversion efficiency (PCE) from 6.03% to 15.50%, representing substantial improvements compared to devices without PCBM. This PCE is the highest efficiency among conventional (n-i-p) Sn-Pb PeSCs reported to date. Moreover, passivating the trap sites of SnO2 and separating the interface between the Sn-containing perovskite and the substrate effectively have improved the stability of the Sn-Pb perovskite in the n-i-p structure. The optimized best device with HT-PCBM has maintained an efficiency of over 90% for more than 300 h at 85 °C and 5000 h at room temperature in a glovebox atmosphere.

Graphene-based optically transparent metasurface for microwave and terahertz cross-band stealth utilizing multiple stealth strategies

Stealth, as a miraculous physical phenomenon, has received widespread attention from the scientific and engineering communities for a long time. Optically transparent stealth devices are of significant importance for the stealth capabilities of aircraft windshields and solar panels. However, the current stealth implementations are limited to a single frequency band due to the strong dispersion of passive materials so that cross-band stealth still remains challenging. In this paper, a novel cross-wavelength stealth strategy is proposed based on multi-layer graphene transparent metasurface, which achieves stealth both in microwave and terahertz frequency bands. Strong resonance is designed to achieve high absorption in the microwave band and diffuse scattering is employed for RCS reduction in the terahertz band. Materials such as graphene and ITO are employed to achieve optical transparency and flexibility of the metasurface. The above design is implemented using numerical simulations and experiments, and the results are in good agreements. This design method that integrates multiple stealth strategies opens up a new approach for cross-band stealth, with potential applications in countering advanced electromagnetic detection.

Simultaneous Passivation of Perovskite Interfaces at Multiple Active Sites Improves Device Performance: Combining Theory and Experiment.

A multisite interface passivation material named 2-mercapto-4-methyl-5-thiazoleacetic acid (MMTA) is used to optimize the perovskite film top interface. DFT calculations and experiments show that MMTA can effectively passivate interface defects. Finally, the champion device's photoelectric conversion efficiency reached 23.44%, which possessed long-term stability.

An airbrush 3D printer: Additive manufacturing of relaxor ferroelectric actuators

The additive manufacturing of electroactive polymer (EAP) devices poses significant challenges due to their distinct structure and dissimilar properties of their constituent materials. It requires deposition of multiple functional materials with different properties, achieving μm-scale resolution in layer thickness, and executing incremental deposition and curing steps while preserving the previously deposited functional material layers. This study introduces an airbrush 3D printer concept and employs it for fabricating EAP transducers. An airbrush 3D printer was constructed by adapting a standard extrusion printer platform and integrating it with a two fluid atomizer (i.e. an airbrush) as the deposition tool. A process was developed for printing of the bending P(VDF-TrFE-CTFE) actuators with carbon black electrodes, and actuators with a single and dual EAP layers were fabricated. The airbrush printer attained in-plane resolution of 0.5mm, thickness resolutions of 0.63 μm and allowed atomizing up to 7% P(VDF-TrFE-CTFE) solutions. The 18 mm × 4 mm EAP actuators achieved 340μm (440 Vpp) and 3.7 mm (400 Vpp, 104 Hz) tip deflections respectively in quasi-static and resonant operation. Airbrush printing therefore proved to be a robust method for printing precursor materials with a wide range of properties, and is anticipated to be a versatile approach for printing other passive and stimuli-responsive materials and devices.