Dimensional Materials Research Articles

Heterojunction engineered MWCNT/Ag[formula omitted] via organic acid and its natural light-assisted photocatalytic efficiency

Compositing photoactive, but unstable semiconductors with low dimensional carbon-based materials and modulating the hetero junction between them can assure more efficient and stable systems for the remediation of severe pollutants. The current study has given emphasis to understand the role of sulfonic acid in making a compact heterojunction between AP and MWCNTs, considering the effective delocalization of carriers and the direct relationship with the photoactivity. The significant reduction in the band gap of AP from 2.320 to 2.0516ev after the introduction of MWCNTs unmistakably confirmed the compatibility between the composite moieties. The intensity of the photoluminescence peak observed at an emission wavelength of 350nm for pure AP was found to be minimized in the composite, which confirms the effective charge delocalization from AP to the conductive MWCNTs. The closest bond distance was observed in the range of 2.3 to 2.5Å between an O atom of Ag3PO4 and a C atom of CNT, which explains the tight contact between the species. The photoactivity studies unambiguously confirmed the potential of the organic acid at the composite interface as it could accomplish 99% dye degradation within a span of 8min, whilst the system without the organic acid exhibited complete degradation within a span of 60min. The p-XRD analysis of the catalyst recovered from the reaction mixture revealed its high stability.

Physically Constructed and Socially Shaped: Sociomaterial Environment and Walking for Transportation in Later Life.

The predictive power of three intersecting environmental dimensions (built structures, social infrastructure, and social capital) on late-life walking was investigated, conceptually based on the ecological framework of place, which posits that a living environment is simultaneously a physical place, a social place, and a set of social bonds. Multilevel models were used to examine the extent to which environments, defined as interactions of the social and material environmental dimensions, reliably predicted walking for transportation among U.S. adults aged 60 years or older in the 2015 National Health Interview Survey (n = 11,180). Random intercepts representing 221 environments showed an intraclass correlation of 21%, indicating high levels of between-environment variance in walking. Social infrastructure had the highest predictive power for walking, followed by material structures and social capital. Synergistic interventions that incorporate the intersecting nature of the sociomaterial environment may be most effective in promoting physical activity in later life.

Spatial Imaginations of “Turkey” and “Europe”: An Introduction

This paper develops the concept of spatial imaginations as the constructions of places as meaningful entities that establish identities of self and other through particular narratives and associated practices. It argues that traditionally, International Relations has ignored question of space despite their obvious centrality to the discipline. This has changed with the “spatial turn”, which has its precursors in critical scholarship, especially drawing on sociology and political geography. The paper traces these contributions to the conceptual development of space in its material and discursive dimensions. It proposes that spatial imaginations are central to relations between “Turkey” and “Europe”, establishing both as meaningful yet contested entities. In the works collated in the special issue of which this paper serves as an introduction, we may thus see facets of three core claim of the spatial turn: that space matters,that space needs to be made, and that spaces need to be formed. Against the prevailing attempts to fix the meaning of the spaces of “Turkey” and “Europe”, I end with a plea to provide room for the articulation of a multiplicity of spatial imaginations.

Full-scale push-out testing of headed stud-steel block connectors in prefabricated steel-concrete composite beams

Full-scale push-out tests of 13specimens were conducted to study the shear behavior of the headed stud-steel block connectors (HSBCs) in prefabricated steel-concrete composite bridge beams, where the key parameters of steel block height, longitudinal connector spacing, presence of oblique rebars in the precast slab, and grouting material were considered. The objective was to develop large shear stiffness, high shear capacity, and sufficient deformability of the connectors in prefabricated steel-concrete composite bridge beams. The results from the push-out tests reveal: two main failure modes the compression failure in the concrete slab and the shear failure in the grouting material and concrete slab; and the HSBC has large shear stiffness, high shear capacity (≈1500kN), and sufficient deformability. Based on the analysis of the shear extrusion dimension of the grouting material and concrete slab, the shear inclination ratio was found approximately to be 1:5, which agrees well with the stipulation specified in the EC4. The height and spacing of HSBCs are the two principal parameters affecting the shear capacity and failure mode of the specimens. By comparing the measured shear capacities of the HSBCs with those calculated by the design formulas for steel blocks and headed studs as specified in the EC4, it is shown that the steel block and headed studs can work together to resist the force between the precast concrete slab and the steel beam.

Efficient GW calculations in two dimensional materials through a stochastic integration of the screened potential

Many-body perturbation theory methods, such as the G0W0 approximation, are able to accurately predict quasiparticle (QP) properties of several classes of materials. However, the calculation of the QP band structure of two-dimensional (2D) semiconductors is known to require a very dense BZ sampling, due to the sharp q-dependence of the dielectric matrix in the long-wavelength limit (q → 0). In this work, we show how the convergence of the QP corrections of 2D semiconductors with respect to the BZ sampling can be drastically improved, by combining a Monte Carlo integration with an interpolation scheme able to represent the screened potential between the calculated grid points. The method has been validated by computing the band gap of three different prototype monolayer materials: a transition metal dichalcogenide (MoS2), a wide band gap insulator (hBN) and an anisotropic semiconductor (phosphorene). The proposed scheme shows that the convergence of the gap for these three materials up to 50meV is achieved by using k-point grids comparable to those needed by DFT calculations, while keeping the grid uniform.

Colloidal Ternary Telluride Quantum Dots for Tunable Phase Change Optics in the Visible and Near-Infrared.

A structural change between amorphous and crystalline phase provides a basis for reliable and modular photonic and electronic devices, such as nonvolatile memory, beam steerers, solid-state reflective displays, or mid-IR antennas. In this paper, we leverage the benefits of liquid-based synthesis to access phase-change memory tellurides in the form of colloidally stable quantum dots. We report a library of ternary MxGe1-xTe colloids (where M is Sn, Bi, Pb, In, Co, Ag) and then showcase the phase, composition, and size tunability for Sn-Ge-Te quantum dots. Full chemical control of Sn-Ge-Te quantum dots permits a systematic study of structural and optical properties of this phase-change nanomaterial. Specifically, we report composition-dependent crystallization temperature for Sn-Ge-Te quantum dots, which is notably higher compared to bulk thin films. This gives the synergistic benefit of tailoring dopant and material dimension to combine the superior aging properties and ultrafast crystallization kinetics of bulk Sn-Ge-Te, while improving memory data retention due to nanoscale size effects. Furthermore, we discover a large reflectivity contrast between amorphous and crystalline Sn-Ge-Te thin films, exceeding 0.7 in the near-IR spectrum region. We utilize these excellent phase-change optical properties of Sn-Ge-Te quantum dots along with liquid-based processability for nonvolatile multicolor images and electro-optical phase-change devices. Our colloidal approach for phase-change applications offers higher customizability of materials, simpler fabrication, and further miniaturization to the sub-10 nm phase-change devices.

Identification of Students' Conceptual and Procedural Errors in Solving Problems in Three-Dimensional Material

Low math skills of students can be seen from the understanding and the assignment of students to a material. One of the clues to determine the extent to which students master the material is to analyze student's mistakes in working on. The study aims to describe the kind of conceptual errors and procedural errors in the student answered question on the three-dimesional material. This study used descriptive qualitative approach. This research subject is class XII IPA SMAN 1 Bengkalis. Techniques of data collection using interviews and documentation written test. The object of this study was grade XII IPA 1 SMAN 1 Bengkalis which amounted to 26 students. This research result is the kind of mistake that most people do students is a conceptual mistake in working on the three dimensional material is 52%. While its procedural errors as much as 48%. Conceptual errors and procedural errors occurred because of the low ability of abstraction and visual abilities in students in answering the questions that are hard to describe and determine the distance to a point on the field of three dimensional material. Low math skills of students can be seen from the understanding and the assignment of students to a material.

Structure and electrochemical properties of CuO-ZnO nanocomposite produced by the one-step novel discharge process

The current study focuses on an alternative strategy for producing nanoparticles (NPs) using one-step electrochemical discharge process (ECDP) in different electrolyte mediums. Current and plasma discharge effects on morphology and mass output rate were examined in detail. FE-SEM and TEM results show dimensional control materials such as rod, flower and rice shapes are produced. The XRD, EDS, UV-vis and Raman characterization techniques confirm the formation of CuO-ZnO NPs with different morphology. The use of two semiconductors (n-type ZnO and p-type CuO) in combination have two different band energies may boost electrochemical performance. From the electrochemical study, the flower-shaped structure has high specific capacity (313 F/g at 2 A/g current density), with 84.1% retention capacitance after 5000 cycles. This study allows us to study the discharge-based composite formation, which could be used in supercapacitors.

Bridging the Discursive and Material Dimensions of Europeanity and Europeanisation

The article aims to capture the significatory diversity of the concepts of Europeanity and Europeanisation, through the development of a semantic map in order to visualize the different concepts that define Europeanity and Europeanisation, and their interconnections. Embedded in the field of Communication and Media Studies, this semantic map combines 19 different approaches, structured through one main dimension, the discursive versus the material, which allows bridging the major rift in the conceptual reflections about Europeanity and Europeanisation. Moreover, the semantic map uses two support dimensions, with the discursive dimension intersecting with the essentialist versus relationist dimension, and the material dimension intersecting with the socio-spatial versus politico-spatial dimension. In order to construct this semantic map, phases of both general and targeted literature reviews were combined with a participatory theory-building method, which was grounded in collaborative knowledge building and collaborative theory construction approaches.

The stability, mechanical, electronic and thermoelectric properties of unexplored monolayer Ca4Sb2O and Ca4Bi2O

Thermoelectric materials can directly convert heat gradient into electricity, thus have attracted much attention in the field of clean energy and ecological protection. In this work, we proposed two novel two−dimensional materials, Ca4Sb2O and Ca4Bi2O, and investigated their stability, mechanical, electronic and thermoelectric properties. We revealed that these two monolayers are direct semiconductors with bandgaps of 1.57 and 1.08 eV, respectively. Due to the lower electron effective mass, the electron mobilities (252.90–799.97 cm2/Vs) are significantly higher than those of hole (58.16–59.21 cm2/Vs), leading to high n-type conductivities (106–107 S/m), as well as high thermoelectric power factors of 28.80 and 10.83 mW K−2 m−1 at 300 K. Also, owing to the low phonon group velocities and high phonon-phonon scattering rates, the monolayers also possess low lattice thermal conductivities of 1.86 and 1.01 W/mK at room temperature, which are dominated by acoustic modes. As a result, Ca4Sb2O and Ca4Bi2O deliver high n-type thermoelectric figure of merit of 0.27 and 0.29 at 300 K, and increase even further to 1.50 and 1.67 at 700 K, suggesting that they are candidates for low - medium temperature thermoelectric appliances.

In defence of ideological struggle against neocolonial self-justifications: Revisiting Asad's Anthropology and the Colonial Encounter amid the decolonial turn

Over the past decade-plus, there has been a surge in anthropological writing on decolonisation. Yet, whereas mid-twentieth century anticolonial revolutionaries fought to uproot imperialism's extractive political economy, certain contemporary decolonial tendencies give primacy, instead, to asserting cultural/epistemological difference. This shift has motivated pertinent critiques, such as that of Nigerian philosopher Olúfẹ́mi Táíwò, of atavistic conceptions of decolonisation. Táíwò's dismissal, however, of the neocolonialism thesis and his conceptual uncoupling of imperialism's material and symbolic dimensions results in a one-dimensional polemic. What gets lost is the much-needed role of decolonisation as an ideological struggle in mobilising populations against an entrenched neocolonial political economy. With this debate as framing, I propose revisiting Talal Asad's 1973 volume, Anthropology and the Colonial Encounter, published at the height of anthropology's disciplinary anti-imperialism. The book's contributors detail how, amid intensifying anticolonial agitation, interwar anthropologists anxious about cultural change among colonised populations advocated a shift to indirect colonial rule through native elites, rather than an abolition of imperialism per se. While spurning colonialism's earlier assimilationist agenda, anthropological calls to institutionalise cultural differences among colonised populations resonated with an imperialist project of incorporating while subverting anticolonial demands. Amid present-day anthropological discussions around decolonisation, these insights remain relevant. This is because contemporary neocolonial relations operate in a manner akin to indirect colonial rule.

Tunning the tilt of the Dirac cone by atomic manipulations in 8Pmmn borophene

Two dimensional quantum materials possessing Dirac cones in their spectrum are fascinating due to their emergent low-energy Dirac fermions. In 8Pmmn borophene the Dirac cone is furthermore tilted, which is a proxy for spacetime geometry, since the future light-cone depends on the underlying metric. Therefore it is important to understand the microscopic origin of the tilt. Here, based on ab-initio calculations, we decipher the atomistic mechanism of the formation of tilt. First, nearest-neighbor hopping on a buckled honeycomb lattice forms an upright Dirac cone. Then, the difference in the renormalized anisotropic second-neighbor hopping, formed by virtual hoppings on one-dimensional chains of atoms, tilts the Dirac cone. We construct an accurate tight-binding model on honeycomb graph for analytical investigation, and we find that substitution of certain boron atoms by carbon provides a way to change the tilt of the cone.

Hierarchical architecture bioinspired CNTs/CNF electromagnetic wave absorbing materials

One dimensional carbon nano material has attracted extensive attention in the field of electromagnetic wave (EMW) absorption due to its large aspect ratio, ultrafine nano networks, good thermal stability and designable surfaces. However, one-dimensional nanomaterials are easy to agglomerate, loss and impedance are mismatched, which seriously restricts their application. How to overcome the agglomeration of one-dimensional nanomaterials, as well as design nano-interface and precisely control the dielectric loss are the key to the research of EMW absorbing materials. Inspired by the dense and regular hierarchical structure of pine branches, we use carbon nano fiber (CNF) converted from bacterial cellulose (BC) as the matrix, and in situ growth amorphous carbon nanotubes (CNTs) on its surface, so as to construct a hierarchical architecture similar to pine leaves in nanoscale, which not only solves the common aggregation problem of one dimensional nanomaterial, but also obtains stronger interface polarization capability through hierarchical nano structure. Furthermore, the amorphous CNTs network have moderate conductivity, which does not lead to impedance mismatch. The reflection loss of CNTs/CNF with a CNTs content of 63.2 wt% can reach −68.2 dB at a thickness of 2.7 mm, and the maximum effective absorption bandwidth reaches 5.5 GHz. The design strategy of hierarchical amorphous carbon nanocomposite integrates strong EMW absorption and good impedance characteristics, the synthesized CNTs/CNF composites exhibit excellent EMW absorption properties.

Ionic Liquids Exhibit the Piezoelectric Effect.

The piezoelectric effect was discovered over a century ago, and it has found wide application since that time. The direct piezoelectric effect is the production of charge upon application of force to a material, and the converse piezoelectric effect is a change in the material dimension(s) upon the application of a potential. To date, piezoelectric effects have been observed only in solid-phase materials. We report here the observation of the direct piezoelectric effect in room-temperature ionic liquids (RTILs). The RTILs 1-butyl-3-methyl imidazolium bis(trifluoromethyl-sulfonyl)imide (BMIM+TFSI-) and 1-hexyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide (HMIM+TFSI-) produce a potential upon the application of force when confined in a cell, with the magnitude of the potential being directly proportional to the force applied. The effect is one order of magnitude smaller than that seen in quartz. This is the first report to our knowledge of the direct piezoelectric effect in a neat liquid. Its discovery has fundamental implications about the organization and dynamics in ionic liquids and invites theoretical treatment.

Fever pitch: spatial, material, and temporal organisational dimensions of gendered peer relations on the school football pitch

ABSTRACT We investigate the importance of spatial, material, and organisational factors to gendered peer relations on the school football pitch. The study is part of an ethnographic research project exploring the relations between school bullying and the institutional context of schooling, focusing on the perspectives of teachers and pupils from preschool class up to grade eight (approximately ages 5–13). The findings in this study are based on participant observations and semi-structured interviews with pupils at three schools in Sweden. Our findings illustrate how social-ecological elements of spatial, material, and organisational factors such as school design, the material construction of the pitches, and the temporal organisation of the space through scheduling promote gendered positioning and fevered interactions which influence peer relations and sometimes contribute to degrading treatment, harassment and bullying. Our study demonstrates how these processes need to be understood as complexly related to social-ecological factors beyond the football pitch setting.

Secret objects in the home: Potency, (in)visibility and everyday relationships

This article argues that the material dimensions of secrecy, which have been neglected within academic research into consumption and into material culture, are ripe for sociological analysis and attention. We draw on two empirical projects – one using qualitative interviews to talk to women about their sex toys and the other ethnographically informed research into things people keep but are no longer using - to explore secret things within the home. By taking a facet methodology approach, we consider secret objects in relation to each other and interrogate how secrets are made (in)visible through strategies and practices around objects within the home and how the potency of secret objects is managed. We make two key arguments: first, considering the relationship between secrecy and intimacy, we argue that there are three dimensions of secrecy (which do not always coalesce): what is known about, what is verbalised, and what is materialised. Second, we redirect the idea of relational work to material things, looking at where things are kept, who they are revealed to and the silences around things, and argue that these practices are part of the work of everyday relationships and intimacies. The article demonstrates that objects are vital in understanding how secrecy, intimacy and everyday relationships are lived and forms part of a wider argument for the sociology of culture to centre the unnoticed and mundane.

Flexoelectric Effect of Ferroelectric Materials and Its Applications

The flexoelectric effect, which exists in all dielectrics, is an electromechanical effect that arises due to the coupling of strain gradients (or electric field gradients) with electric polarization (or mechanical stress). Numerous experimental studies have demonstrated that ferroelectric materials possess a larger flexoelectric coefficient than other dielectric materials; thus, the flexoelectric response becomes significant. In this review, we will first summarize the measurement methods and magnitudes of the flexoelectric coefficients of ferroelectric materials. Theoretical studies of the flexoelectric coefficients of ferroelectric materials will be addressed in this review. The scaling effect, where the flexoelectric effect dramatically increases when reducing the material dimension, will also be discussed. Because of their large electromechanical response and scaling effect, ferroelectric materials offer vast potential for the application of the flexoelectric effect in various physical phenomena, including sensors, actuators, and transducers. Finally, this review will briefly discuss some perspectives on the flexoelectric effect and address some pressing questions that need to be considered to further develop this phenomenon.

4,4−Diaminodiphenyl methane functionalized reduced graphene oxide/CoFe−layered double hydroxide obtained by in−situ hydrothermal as a high−performance absorber

The self−assembly among different two−dimensional materials could effectively improve the self−stacking effect and promote repeated reflection and refraction of incident electromagnetic wave (EMW). The polarization effect caused by the heterogeneous contact also helps the attenuation of EMW. In this study, the in−situ hydrothermal approach was used to effectively fabricate petal−like CoFe−layered double hydroxide sheets (CoFe−LDH) grown on reduced graphene oxide (RGO) functionalized by 4,4−diaminodiphenyl methane (DDM). The microwave absorption properties of DDM−functionalized RGO/CoFe−layered double hydroxide composites (DDM−RGO/LDH) were investigated. When the loading of DDM−RGO is 40.0 ​mg, the reflection loss reached −60.0 ​dB at 5.28 ​GHz, resulting in great EMW absorption performance. The effective absorption bandwidth at 2.00 ​mm is 5.28 ​GHz. The results show that DDM−RGO/LDH has a wide microwave absorption bandwidth and strong absorption capability, thus could be applied as an advanced EMW absorbing material.

“Ideology and simultaneously more than mere ideology”: On Habermas’ reflections and hypotheses on a further structural transformation of the political public sphere

“Ideology and simultaneously more than mere ideology”: On Habermas’ reflections and hypotheses on a further structural transformation of the political public sphere

Feasibility of Integrating Bimetallic Au-Ag Non-Alloys Nanoparticles Embedded in Reduced Graphene Oxide Photodetector

To coordinate the resonant wavelength of the plasmonic nanoparticles (NPs), the emission band of the reduced graphene oxide (rGO) photodetector at the NIR-region is crucial for the optimal plasmon-enhanced luminescence in the device. In contrast to monometallic NPs, where limits the dimensions and extended resonant wavelength, we integrated an Au-Ag bimetallic NPs (BMNPs) to enable resonance tuning at the longer wavelength at the excitation source of 785 nm. These features showed an increase in radiative recombination rates as well as the quantum yield efficiency of the device. The BMNPs were produced from the dewetting process of 600 °C and 500 °C, both at 1 min after the deposition thickness layer of Au (8 nm) and Ag (10 nm) on the Si substrate using the electron-beam evaporation process. Our BMNPs-rGO photodetector exhibited the responsivity of 2.25 · A W−1, Jones of specific detectivity of 2.45×1011Jones, and external quantum efficiency (EQE) of 356%. The rise time and fall time for the photodetector were 32 ns and 186 ns, respectively. This work provided an essential information to enable the versatile plasmon-enhanced application in 2-dimensional (2D) material optoelectronic devices.