Dimensional Materials Research Articles

Bond strength of epoxy-based composites at the interface with surface deposited metal layer: A comparative study with different dimensional fillers

With the complexity of the working environment, pure epoxy resin can no longer meet the requirements, and the weak interfacial bonding between metal layer and epoxy-based composites limits its development. In this work, we propose a novel molecular grafting modification technique by using the active functional groups of polymers, which can apply to epoxy-based composites with various fillers to improve the adhesive strength of the interface between the metal film and matrix. 3D surface profile and surface wettability were used to characterize the effect of fillers on the surface of epoxy composites. Scanning electron microscope (SEM) and Raman spectroscopy were utilized to judge the interface failure modes of the composites. Peeling test and surface-enhanced Raman scattering (SERS) were conducted to examine how fillers affected adhesion. The results showed that silane grafting substantially improved the bonding between the epoxy-based composite matrix and the metal layer without the need for alkaline washing and palladium (Pd) activation steps on the substrate. The average adhesive strength can reach a maximum of 17.76 N/cm. The study also revealed the effect of filler size on the interfacial adhesive strength. The interfacial adhesive strength was increased by two dimensional lamellar materials, decreased by one-dimensional tubular materials, and remained unaffected by zero-dimensional spherical materials. This study may have positive implications for improving interfacial bonding between metal and polymer composite surfaces.

The affective economy of ‘self-deportation’: materiality, spatiality, temporality

ABSTRACT The increased securitisation of the borders bounding and intersecting Europe has led to the formation of makeshift tent settlements along established routes of irregular migration. Built at permeable border points, illegalised migrants live in these informal camps while they attempt to cross into a neighbouring country. One such camp, Dankix, lies on the northern French coast in the outskirts of Grande-Synthe. While its Kurdish inhabitants aim to cross the Channel to the United Kingdom, some return to Kurdistan using the state’s programme of retour volontaire, or ‘voluntary return’. I examine the affective economy of state-assisted return through the experiences of one family as they move between the social and juridical categories of illegalised and legalised. As they simultaneously cross borders thousands of miles apart, they circulate affective energies that contain particular material, spatial, and temporal dimensions. This affective economy both reveals and transforms the relationships between emplacement, belonging, and illegalisation.

Will the ‘Real Reader’ Please Stand Up? ‘Bookishness’ in Amitav Ghosh’s The Shadow Lines

This essay examines the palpable presence of books and the printed word in Amitav Ghosh’s The Shadow Lines (1988) and its entwinement with the brief, “bookish” life of the character Tridib, who plays a pivotal role in the narrative. It draws upon a phrase from Amitav Ghosh’s oeuvre–the “real reader”–to explore the idealized figure of the reader and storyteller embodied by Tridib. This idealized figure, as this essay highlights, has a history stretching back to the early days of print in colonial India, and important antecedents in the modern Bengali literary canon. It is also a figure constituted by material dimensions of book-ownership and by dominant ideologies on the cultural value of book-owning and reading. What does the tale of the “bookish” storyteller stand for in the postcolonial context, in a narrative that holds his readerly qualities in the highest esteem?

Effect of dimensional confinement on the memristive properties of the perovskite-inspired novel CuxAgBiI4+x halide compound

Low dimensional halide perovskite materials have shown significant performance enhancement in memristor devices. In search of highly stable and robust perovskites, several perovskite-inspired structures are proposed. This present study demonstrates the fabrication of novel lead-free all-inorganic CuxAgBiI4+x (x = 1 or 2) as the active material sandwiched between gold and indium doped tin oxide electrodes. Initial studies revealed that the memristor devices consisting of two-dimensional Cu2AgBiI6 have higher current on/off ratio as compared to the three-dimensional CuAgBiI5. This is ascribed to the elevated Schottky barrier at the Au/Cu2AgBiI6 interface as suggested by ultraviolet photoelectron spectroscopy, which resulted low current in the high resistance state (HRS) of the device. Kelvin probe force microscopy shows that the charge accumulation property is similar in both the materials although the CuAgBiI5 possesses less vacancies. However, the high switching window of the Cu2AgBiI6-based device succeeded in retaining the stable on/off ratio in the cycling endurance. Artificial synaptic characterizations have been carried out in the Cu2AgBiI6 based device due to low HRS current. The device could mimic paired-pulsed facilitation, transition from short-term to long-term potentiation and thus establishes the fact that low dimensional perovskite-type materials possess great potential for memristor application.

Artificial Perovskite Multiple Quantum Well Optoelectronics

Metal halide perovskite-based photovoltaics and light-emitting diodes (LEDs) have exhibited a promising trajectory toward commercial viability, nearing the performance levels of them to the commercially established materials. A particularly encouraging avenue involves tailoring the various dimensions of perovskite materials, notably through the implementation of perovskite multiple quantum wells (MQWs), to amplify their potential in optoelectronic applications. This comprehensive review delves into recent breakthroughs in both self-assembled perovskite MQWs and artificially fabricated counterparts, elucidating their mechanisms and performance characteristics. By gathering and evaluating the very original and the latest research findings, this review aims to provide valuable insights into the underlying principles governing optical behaviors of perovskite MQWs as well as optoelectronic and photonic applications. Furthermore, it outlines prospective research pathways, delineating potential pathways for further exploration and optimization of perovskite MQW-based devices. Through this general evaluation on the recent advancements and prospects, this review contributes to advancing the understanding and application of perovskite materials in next-generation optoelectronic and photonic technologies.

Preparation of three dimensional boron nitride-aluminum oxide dual thermal network resin-based composite materials and their performance study

With the gradual miniaturization and integration of electronic devices, the design and development of new high thermal conductivity polymer-based composite materials are crucial for enhancing the performance of modern electronic devices. In this study, three-dimensional boron nitride (3D-BN) aerogels with vertically aligned structures were prepared using the ice templating method, serving as the primary thermal conductive network. Subsequently, aluminum oxide (Al2O3)/epoxy resin (EP) nanofluids were infiltrated into the aerogel’s air pores using vacuum impregnation. The Al2O3 particles in contact with each other formed the secondary thermal conductive network. Thus, a 3D BN-Al2O3/EP composite material with a dual thermal conductive network structure was successfully fabricated. The composite material exhibited a high thermal conductivity coefficient of 1.077 Wm−1K−1 when loaded with 17.67 wt% BN and 26.23 wt% Al2O3, representing a 496 % increase compared to pure EP and a 211 % increase compared to 3D-BN/EP composite materials. Furthermore, this composite material demonstrated excellent thermal stability and mechanical properties. This work provides a new direction for designing novel polymer-based composite materials with low filler loading and high thermal conductivity performance.

Flexoelectricity Modulated Electron Transport of 2D Indium Oxide.

The phenomenon of flexoelectricity, wherein mechanical deformation induces alterations in the electron configuration of metal oxides, has emerged as a promising avenue for regulating electron transport. Leveraging this mechanism, stress sensing can be optimized through precise modulation of electron transport. In this study, the electron transport in 2D ultra-smooth In2O3 crystals is modulated via flexoelectricity. By subjecting cubic In2O3 (c-In2O3) crystals to significant strain gradients using an atomic force microscope (AFM) tip, the crystal symmetry is broken, resulting in the separation of positive and negative charge centers. Upon applying nano-scale stress up to 100nN, the output voltage and power values reach their maximum, e.g. 2.2mV and 0.2pW, respectively. The flexoelectric coefficient and flexocoupling coefficient of c-In2O3 are determined as ≈0.49nCm-1 and 0.4V, respectively. More importantly, the sensitivity of the nano-stress sensor upon c-In2O3 flexoelectric effect reaches 20nN, which is four to six orders smaller than that fabricated with other low dimensional materials based on the piezoresistive, capacitive, and piezoelectric effect. Such a deformation-induced polarization modulates the band structure of c-In2O3, significantly reducing the Schottky barrier height (SBH), thereby regulating its electron transport. This finding highlights the potential of flexoelectricity in enabling high-performance nano-stress sensing through precise control of electron transport.

Inclusive teaching practices implemented in primary school bilingual programmes in Spain: Teachers’ views and associated factors

Promoting plurilingualism and the provision of inclusive and good-quality education are currently two converging challenges. However, despite the difficulties expressed by teachers in catering to diversity in their bilingual classrooms, the implementation of inclusive practices has received little attention. This study aims to analyse how teachers perceive their use of inclusive practices in primary school bilingual programmes and to identify associated sociodemographic characteristics. In total, a sample of 300 teachers completed the ad hoc designed Inclusive Teaching Practices in Bilingual Education scale. The results of the survey showed that inclusive practices associated with the dimensions of linguistic aspects, materials and resources, and assessment are more frequently used than those associated with methodology, groupings, and collaboration with teachers and families. Moreover, those teachers who were English specialists, were more experienced at teaching in a bilingual programme, used English to a greater extent in the classroom, were highly proficient in English, and who received help from a support teacher used inclusive practices more frequently in their classrooms. Overall, teachers in bilingual education have a positive perception of their use of inclusive practices, but more work is needed regarding collaboration and providing a more personalised approach to education through appropriate scaffolding strategies and feedback.

Deep-Learning-based damage detection of an experimentally tested full-scale wind turbine blade.

Reducing the Operation and Maintenance (O&M) costs of Wind Farms can substantially contribute towards adopting environmentally sustainable and cost effective energy sources. O&M costs in Wind Turbines can account up to 50% of the Turbine’s whole life cycle, with the majority of it being the frequent manual inspection needed for Wind Turbine Blades (WTB). Vibration-based structural health monitoring (SHM) approaches can be used for detecting WTB damages in an early state, before they lead to catastrophic failure, while they can be used to perform inspection on an informed basis, reducing O&M costs. In the present study, a data-driven damage detection framework is developed for WTBs. A Finite Element Model (FEM) of a full-scale WTB (the Aventa AV-7 “Light Wind Turbine”, sold under the Leichtwindanlagen© name) is developed in ABAQUS FEA using sparce material properties and dimensions and subsequently modified to match a physical WTB. Damage is modelled in the form of a Trailing Edge (TE) longitudinal crack propagated in a stepwise manner. The FE model is updated based on the geometry altering and material property degrading effects of the TE crack. Numerical simulations are performed to obtain the dynamic responses of the blade, under white noise and chirp excitation. A damage detection framework is then developed using Auto-Regressive, with exogenous excitation (ARX) or without (AR), models and its Nonlinear counterparts NARX and NAR models. In addition, model dimensionality reduction is performed using Principal Component Analysis (PCA) and Deep-Autoencoders (D-AE). The results are presented in terms of Receiver Operating Characteristics (ROC) curves.

Computational modeling of CH4 and CO2 adsorption on monolayer graphenylene: Implications for optoelectronic properties and hydrogen production

Graphenylene (GP) is a two–dimensional carbon allotrope with a hexagonal lattice structure containing periodic pores. The unique arrangement of GP offers potential applications in electronics, optoelectronics, energy storage, and gas separation. Specifically, its advantageous electronic and optical properties, make it a promising candidate for hydrogen production and advanced electronic devices. In this study, we employ a computational chemistry–based modeling approach to investigate the adsorption mechanisms of CH4 and CO2 on monolayer GP, with a specific focus on their effects on optical adsorption and electrical transport properties at room temperature. To simulate the adsorption dynamics as closely as possible to experimental conditions, we utilize the self–consistent charge tight–binding density functional theory (SCC–DFTB). Through semi–classical molecular dynamics (MD) simulations, we observe the formation of H2 molecules from the dissociation of CH4 and the formation of CO + O species from carbon dioxide molecules. This provides insights into the adsorption and dispersion mechanisms of CH4 and CO2 on GP. Furthermore, we explore the impact of molecular adsorption on optical absorption properties. Our results demonstrate that CH4 and CH2 affects drastically the optical adsorption of GP, while CO2 does not significantly affect the optical properties of the two–dimensional material. To analyze electron transport, we employ the open–boundary non–equilibrium Green's function method. By studying the conductivity of GP and graphene under voltage bias up to 300 mV, we gain valuable insights into the electrical transport properties of GP under optical absorption conditions. The findings from our computational modeling approach might contribute to a deeper understanding of the potential applications of GP in hydrogen production and advanced electronic devices.

Norwegian ECEC teachers’ play practices with children aged 2-3 years

ABSTRACT The present study investigated early childhood education and care (ECEC) teachers’ practices when they were engaged in play with children aged 2 to 3 years old. Both in a Norwegian context and internationally the number of younger children in ECEC is increasing, and there is a need for knowledge about what characterizes high-quality teacher practices at play. Eighteen Norwegian teachers were filmed interacting with small groups of two to five children (a total of 54 children, mean age 35 months; range 28–41). The video data (18 play situations; total = 4 hours) were transcribed and analyzed using the theoretical framework of intersubjective space, emphasizing the sematic, material, and social dimensions of the interactions between the teachers and children. The results revealed three main characteristics of teachers’ play practices: creating connections in play, expanding play, and regulating play. Although these characteristics were present in many observations, our analysis revealed variations between the teachers in terms of creating connections, expanding, and regulating. These variations can be decisive for play to continue, develop, or end. In addition, teachers’ practices appear to be crucial for some children to be included in play.

Wire and arc additive manufacturing for strengthening of metallic components

Wire and arc additive manufacturing (WAAM), also known as wire arc directed energy deposition (WA-DED), offers valuable capabilities not only for manufacturing but also for strengthening and repairing aging components. This paper employs the finite element (FE) method to investigate the influence of deposition parameters on the strengthening efficiency of damaged steel plates strengthened by WAAM material. The study calibrates the inherent strain method (ISM) with thermo-mechanical analysis to accurately predict residual stresses (RS) in manufactured samples, demonstrating that the ISM enhances computational efficiency while effectively predicting RS. It thoroughly examines key parameters such as the deposition direction, maximum thickness, and the geometric configuration of the WAAM material, including shapes and in-plane dimensions. The results indicate that deposition perpendicular to the loading direction provides better performance compared to deposition along the loading direction as it induces less normal and through-thickness stresses. Furthermore, this research determines the optimal maximum thickness for the WAAM material, showing that an increase in thickness can lead to higher maximum tensile stresses at the interface between the newly WAAM material and the underlying base plate. The study also establishes the optimal in-plane dimensions for the WAAM material. The results suggest placing the maximum thickness of WAAM material near the damaged area and gradually decreasing it in two directions to ensure sufficient stiffness around the cracked area, while avoiding an abrupt change in stiffness. This approach generates appropriate compressive stresses around the crack tip and decreases maximum tensile stresses in the plate. The study further illustrates that employing a proper printing strategy without a subsequent machining process can effectively reduce the maximum tensile stress in the steel plate while minimizing material usage.

Landscape geographies: Interdisciplinary landscape research and a new framework to apply landscape as method

The landscape concept’s disciplinary ambiguity and its broad range of definitions have resulted in the term’s unruly reputation. More recent scholarship, however, suggests that the term’s interdisciplinary application challenges its contentious origins, creates new pathways for co-creation, and encourages more direct interventions in informing policy. I therefore suggest there is a growing realm of landscape geographies, exploring alternative ways of knowing and being in landscapes across broader spatial, temporal, and ontological scales. Given that it can be difficult to navigate the complicated matrix of landscape definitions, theories, and methodologies, I position landscape as a method and introduce a new model of landscape analysis that includes three overlapping approaches to investigate a landscape’s material, symbolic, and affective dimensions. I conclude that embracing a wider spectrum of landscape geographies will help to elevate a more diverse range of voices, inspiring interdisciplinary conversations that contend with landscape futures in a rapidly changing world.

Photoluminescence Quenching Upon Growth of Metal Nanoparticles: Quantum-Mechanical Views.

In dictating the optical processes in metal nanoparticles, for instance, quantum nature of free electrons is significantly dominant and plays very crucial roles at the level of nanoscale dimensions of materials. As consequences of the quantum-confinement effects on the conduction electrons, surface-plasmon resonance induced optical absorption and light emission properties of metal nanoparticles are found to be strongly dependent on physical dimensions of the nanomaterials. In addition, surface-confined acoustic vibration (phonon) modes have been experimentally observed to depend on the sizes of the metal nanoparticles. Also, interestingly, tuning of the surface-plasmon resonance condition is found to enhance the intensity of the acoustic Raman modes in metal nanoparticles. The study highlights the role of plasmon-phonon coupling in Co metal nanoparticles embedded in a silica-glass. In the research field of nanosciences and nanotechnologies, extraordinary behaviour and properties of nanoscale matters are investigated. In this context, interesting studies have been discussed in this review article to elaborate optical, chemical and photoluminescence properties of nanoscale Ag metal particles. Subtle detection of optical phenomena associated with the excited many-body electronic processes in the metal nanoparticles, for example, are very interesting but definitely challenging. Here we make an attempt to find out how the thermal growth of Ag metal nanoparticles in a glass matrix snuffs out the light emission from the samples? Quantum mechanical interpretations of the underlying processes about the quenching of photoluminescence phenomena with the growth of the metal nanoparticles will help to fine tune the optical properties of plasmonic systems as well as to harness potential applications of the nanomaterials.

A parylene/graphene UV photodetector with ultrahigh responsivity and long term stability

Long term stability, high responsivity, and fast response speed are essential for the commercialization of graphene photodetectors (GPDs). In this work, a parylene/graphene UV photodetector with long term stability, ultrahigh responsivity and fast response speed, is demonstrated. Parylene as a stable physical and chemical insulating layer reduces the environmental sensitivity of graphene, and enhances the performances of GPDs. In addition, utilizing bilayer electrodes reduces the buckling and damage of graphene after transferring. The parylene/graphene UV photodetector exhibits an ultrahigh responsivity of 5.82 × 105 AW−1 under 325 nm light irradiation at 1 V bias. Additionally, it shows a fast response speed with a rise time of 80 μs and a fall time of 17 μs, and a long term stability at 405 nm wavelength which is absent in the device without parylene. The parylene/graphene UV photodetector possesses superior performances. This paves the way for the commercial application of the high-performance graphene hybrid photodetectors, and provides a practical method for maintaining the long term stability of two dimensional (2D) materials.

Investigation of the usage of carbon-based two dimensional materials in lithium sulfide (Li–S) batteries

After the synthesis of graphene (Gr), the other two-dimensional (2D) allotropes of carbon based materials have been predicted theoretically or synthesized by experimentally. Two of these nanomaterials are graphyne (Gy) and graphdiyne (Gdy) which are close relatives of Gr and can be synthesized in bulk. While carbon atoms in Gr bonds with sp2 bonds, Gy and Gdy comprise sp and sp2 hybridized carbon atoms with high degrees of π conjugation that features uniformly distributed pores. So, these intrinsic nanopores add distinction to Gy and Gdy with respect to the Gr especially for energy storage applications. Nowadays, the researchers are studying to improve the storage capacity of Lithium-ion batteries (LIBs). However, Lithium–Sulfur (Li–S) batteries can store approximately five times more energy in terms of energy density compared to LIBs. In this study, we have systematically investigated the lithium polysulfides (LixSy; 1≤x≤2,1≤ y ≤ 8) adsorbed on Gr, Gy and Gdy monolayers by means of density functional theory (DFT) calculations. Our results reveal that, the presence of sp bonds and the size of nanopores in the structure extremely affect the adsorption energy of small sized LixSy clusters. However, the adsorption energies obtained with increasing the size of LixSy clusters are almost similar in Gr, Gy and Gdy monolayers. The diffusion barrier energy values obtained for LixSy clusters indicate that the migration of clusters on Gr may be easy but it is hard on Gdy and especially on Gy due to the pore networks in the structures acting as traps to anchor the LixSy clusters. In addition, we have investigated the double adsorption of LixSy clusters on Gr, Gy and Gdy structures to search the shuttle effect. It can be reported that LixSy clusters do not bind each others and do not create long polysulfide chains, which is not requested.

Adsorption of Water on Vacancy Defective h-BN Bilayer at B and N Sites

<>Two dimensional (2D) materials are used to manufacture the various gadgets. Their properties are therefore appealing. In the present work, we have studied the structural, electronic, and magnetic properties of 2D bilayer hexagonal-Boron Nitride (h-BN), single B vacancy defect on h-BN (B-hBN), single N vacancy defect on h-BN (N-hBN), water adsorption; on B-hBN (w-B-hBN) and on N-hBN (w-N-hBN), materials by spin-polarized density functional theory (DFT) methods employing Quantum ESPRESSO (QE) computational tools. The structural stability of the h-BN, B-hBN, N-hBN, w-B-hBN, & w-N-hBN materials has been investigated by determining their minimum ground state energy and binding energy, and found that they are stable materials. The pristine h-BN bilayer supercell structure is also found to be more compact than other defective configurations. By analyzing the band structures and density of states (DoS) plots of these materials, we have examined their electronic properties, and found that pristine h-BN has a broad bandgap, whereas B-hBN, N-hBN, w-B-hBN, & w-N-hBN exhibit semiconducting nature. The DoS and partial density of states (PDoS) computations of the considered materials are used to study their magnetic properties. It is found that pristine h-BN is a non-magnetic, and B-hBN, N-hBN, w-B-hBN & w-N-BN are magnetic materials. Therefore, vacancy defects on pristine h-BN, and water adsorption on vacancy defected h-BN materials cause it to change from non-magnetic to magnetic. They could find use in the domain of device applications.

The Question of Adequacy, from Hermeneutics to Writing Strategies

AbstractThe postulate of adequacy had been extensively questioned and deepened in the area of hermeneutics and interpretive social sciences. Some of the protagonists of this ongoing debate stress that the interpretation of human action has much in common with the interpretation of semiotic objects including texts and narratives. This debate goes back to a long tradition in the philosophy of human or social sciences. Here, considering recent exchanges in the fields of the history of ideas, rhetoric, and ethnography, we address basic epistemological and methodological issues about the interpretation of meaning and its adequacy. We argue that one must ascertain performativity on both sides of the meaning process: on the side of the semiotic object (speech acts, social rituals, texts, images…) and on the side of the interpreter (second-degree understanding, description, explanation…) We also argue that this theoretical discussion is more relevant and fruitful for the humanities and social sciences when it includes the question of writing strategies. In this way, it is possible to envision the practical moment of hermeneutic understanding, embracing its material, ethical, and political dimensions.

Enhancing the Glucose Sensing Properties of Silicene Through Transition Metal Doping: a DFT Investigation

AbstractThe attractive physiochemical properties of two dimensional materials demonstrate them to be an emerging class of potential candidates for use in sensing devices. Studies have shown that silicene can act as an excellent chemical sensor; however, no work has been studied about silicene as a glucose sensor. In this paper, using density functional theory, the interaction of pristine silicene and transition metal‐doped (Ag, Au, Cu, Ni, and Pt) silicene is studied with glucose molecules. The calculated adsorption energy, energy gap, and charge transfer value confirmed that the nickel‐doped silicene sheet can be a good glucose sensor with high sensitivity, moderate recovery time, and high conductivity. Further, the electron localization function and the reduced density gradient confirm the physisorption between the glucose molecule and the metal‐doped silicene sheets.

Effect on structural, electronic and optical properties of mixed functionalized two dimensional Sc2CTxT’1-x MXenes: A DFT study

MXenes, two dimensional (2D) materials are widely used in various applications such as optoelectronics, energy storage, sensors, supercapactiors and electromagnetic shielding due to their suitable physical characteristics. Previous studies have indicated that the physical properties of MXenes are dependent on surface terminations and by controlling them their properties may be tuned and controlled. In this work after determining the stable geometry, the effect of mix functionalization on the structural, electronic and optical properties of bare Sc2C MXene and mixed functionalized Sc2CTxT’1-x MXenes by using density functional theory (DFT) is investigated. All compositions of mixed functionalized Sc2CTxT’1-x MXenes such as Sc2COH, Sc2CO0·25OH0.75, Sc2CO0·5OH0.5, Sc2CO0·75OH0.5 and Sc2CO MXenes have shown band gap and showed semiconductor behavior as compared to bare Sc2C MXene. Furthermore, the effect of mix functionalization on optical properties such as absorption, dielectric function, refractive index, conductivity and loss function has also been calculated.