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Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 382
Author(s):  
Chelsea D. Appleget ◽  
Juan Sebastian Riano ◽  
Andrea M. Hodge

The microstructural transformations of binary nanometallic multilayers (NMMs) to equiaxed nanostructured materials were explored by characterizing a variety of nanoscale multilayer films. Four material systems of multilayer films, Hf-Ti, Ta-Hf, W-Cr, and Mo-Au, were synthesized by magnetron sputtering, heat treated at 1000 °C, and subsequently characterized by transmission electron microscopy. Binary systems were selected based on thermodynamic models predicting stable nanograin formation with similar global compositions around 20–30 at.%. All NMMs maintained nanocrystalline grain sizes after evolution into an equiaxed structure, where the systems with highly mobile incoherent interfaces or higher energy interfaces showed a more significant increase in grain size. Furthermore, varying segregation behaviors were observed, including grain boundary (GB) segregation, precipitation, and intermetallic formation depending on the material system selected. The pathway to tailored microstructures was found to be governed by key mechanisms and factors as determined by a film’s initial characteristics, including global and local composition, interface energy, layer structure, and material selection. This work presents a global evaluation of NMM systems and demonstrates their utility as foundation materials to promote tailored nanomaterials.


2022 ◽  
pp. 107754632110564
Author(s):  
Nuruzzama M Khan ◽  
R Suresh Kumar

This study is aimed at incorporating the zig-zag effect by Murakami zig-zag function in the development of a finite element model for active constraining layer damping treatment of functionally graded sandwich plates. The present sandwich construction consists of functionally graded facings distanced by a ceramic core. The substrate functionally graded plate is subjected to active constraining layer damping treatment, which in itself is a two-layered material system comprised of a viscoelastic layer and a 1–3 piezoelectric composite layer. The deformation kinematics of the functionally graded sandwich plate active constraining layer damping system is shaped using Murakami zig-zag function , and the finite element model is obtained by the virtual work principle. A standard feedback control system has been implemented, and a MATLAB subroutine has been developed to present the open- and closed-loop responses. Substrate plates with functionally graded configurations 1-1-1, 1-2-1, and 2-1-2 are considered to evaluate the effect of active constraining layer damping on damping the frequency responses of these plates. Investigation on damping performance has been carried out, bearing in mind the change in power-law index with top and bottom ceramic-/metal-rich surfaces. Also, the effect of variation in fiber orientation angle (obliquely reinforced) of the piezoelectric composite material on the active constraining layer damping performance has been examined thoroughly.


2022 ◽  
Vol 11 (1) ◽  
Author(s):  
Shuki Enomoto ◽  
Tomoya Tagami ◽  
Yusuke Ueda ◽  
Yuta Moriyama ◽  
Kentaro Fujiwara ◽  
...  

AbstractLead-halide perovskites are highly promising for various optoelectronic applications, including laser devices. However, fundamental photophysics explaining the coherent-light emission from this material system is so intricate and often the subject of debate. Here, we systematically investigate photoluminescence properties of all-inorganic perovskite microcavity at room temperature and discuss the excited state and the light–matter coupling regime depending on excitation density. Angle-resolved photoluminescence clearly exhibits that the microcavity system shows a transition from weak coupling regime to strong coupling regime, revealing the increase in correlated electron–hole pairs. With pumping fluence above the threshold, the photoluminescence signal shows a lasing behavior with bosonic condensation characteristics, accompanied by long-range phase coherence. The excitation density required for the lasing behavior, however, is found to exceed the Mott density, excluding the exciton as the excited state. These results demonstrate that the polaritonic Bardeen–Cooper–Schrieffer state originates the strong coupling formation and the lasing behavior.


Author(s):  
ANINA ANJU B ◽  
Soma Dutta

Abstract The intricacies in identifying the appropriate material system for energy storage applications have been the biggest struggle of the scientific community. Countless contributions by researchers worldwide have now helped us identify the possible snags and limitations associated with each material/method. This review intends to briefly discuss state of the art in energy storage applications of dielectric materials such as linear dielectrics, ferroelectrics, anti-ferroelectrics, and relaxor ferroelectrics. Based on the recent studies, we find that the eco-friendly lead-free dielectrics, which have been marked as inadequate to compete with lead-based systems, are excellent for energy applications. Moreover, some promising strategies to improve the functional properties of dielectric materials are discussed.


Author(s):  
Joachim Hausmann ◽  
Stefan Schmidt

Thermal residual stresses (TRS) in hybrid materials and structures occur by the mismatch of thermal expansion of different materials. Especially when combining metals with carbon fiber reinforced plastics (CFRP), a significant level of internal stresses can be reached. High processing temperatures and high stiffness of the constituents are also responsible for high stress levels. Laminates of thermoplastic CFRP (unidirectional carbon fiber reinforced polyamide 6) and stainless steel foils are a suitable material system to examine the TRS in detail. Since TRSs in the steel fraction are of tensile nature, these superpose to externally applied loads, resulting in higher efforts for the material and thus reduced lifetimes under cyclic fatigue loading. Therefore, a reduction of TRS is desired. Two methods for TRS reduction were applied, and its influence on fatigue lifetime was investigated. Firstly, specimens were stretched by a preloading to reduce TRS by yielding of the metal. Secondly, non-symmetric laminates were gradually cooled down after consolidation to compensate TRS formation by non-symmetric shrinkage. While preloading of materials and structures is known for TRS modification, the gradually cooling is not established, yet. Both modification principles were numerically investigated before experimental validation. A significant increase of lifetime was reached by TRS reduction.


2021 ◽  
Author(s):  
Long Wang ◽  
Wei-Hung Chiang ◽  
Kenneth J. Loh

Abstract High-performance piezoresistive nanocomposites have attracted extensive attention because of their significant potential as next-generation sensing devices for a broad range of applications, such as monitoring structural integrity and human performance. While various piezoresistive nanocomposites have been successfully developed using different material compositions and manufacturing techniques, current development procedures typically involve empirical trial and error that can be laborious, inefficient, and, most importantly, unpredictable. Therefore, this paper aims to propose and validate a topological design-based methodology to strategically manipulate the piezoresistive effect of nanocomposites to achieve a wide range of optimized strain sensitivities without changing the material system. In particular, this work designed patterned nanocomposite thin films with stress-concentrating and stress-releasing topologies. The strain sensing properties of the different topology nanocomposites were characterized and compared via electromechanical experiments. Those results were compared to both linear and nonlinear piezoresistive material model numerical simulations. Both the experimental and computational results indicated that the stress-concentrating topologies could enhance strain sensitivity, whereas the stress-releasing topologies could significantly suppress bulk film piezoresistivity.


2021 ◽  
Vol 1 (2) ◽  
pp. 218-223
Author(s):  
DEDEK MARTHA DEWI

This study aims to determine the cognitive abilities of students on the material system of motion in humans through charta media in class VIII E students of SMP Negeri 1 Cikupa, Tangerang Regency. The method used is descriptive quantitative. The population in this study were all eighth grade students of SMP Negeri 1 Cikupa, Tangerang Regency, in the 2014/2015 academic year. The sample used is class VIII E consisting of 40 people. The data collection technique was carried out by purposive sampling. Data collection techniques using pretest-posttest. The instrument used is an objective test in the form of multiple choice to measure cognitive ability. Based on the results of the study, it can be concluded that the use of charta learning media can increase the value of cognitive abilities of class VIII E students of SMP Negeri 1 Cikupa, Tangerang Regency. ABSTRAKPenelitian ini bertujuan untuk mengetahui kemampuan kognitif siswa pada materi system gerak pada manusia melalui media charta pada siswa kelas VIII E SMP Negeri 1 Cikupa Kabupaten Tangerang. Metode yang digunakan adalah deskriptif. Populasi dalam penelitian ini adalah seluruh siswa kelas VIII SMP Negeri 1 Cikupa Kabupaten Tangerang tahun ajaran 2014/2015. Sampel yang digunakan yaitu siswa kelas VIII E yang terdiri dari 40 orang. Teknik pengambilan data dilakukan secara purpose sampling. Tenik pengumpulan data menggunakan pretest-postest. Instrumen yang digunakan adalah tes objektif berupa pilihan ganda untuk mengukur kemampuan kognitif. Berdasarkan hasil penelitian dapat disimpulkan bahwa penggunaan media pembelajaran charta dapat meningkatkan nilai kemampuan kognitif siswa kelas VIII E SMP Negeri 1 Cikupa Kabupaten Tangerang.


2021 ◽  
Author(s):  
◽  
Ricardo Quirarte

<p>Studying men and masculinities in Mexico through feminist sociology is necessary to tackle gender inequalities. These inequalities can be as extreme as the institutional, sexual and physical violence that occur in disproportionate numbers, or as quotidian as the micro-machismos that go unnoticed as forms of everyday gender violence. It is paramount to understand masculinity as a system of domination and differentiation as well as a gender identity that is performed by bodies that feel, are affected and recognise themselves as masculine and as men. By doing so, the road towards equality will include a strong critique of how men have learned to pursue a certain form of masculinity.  To question men’s relation with masculinity and their experience of recognising themselves as such, this thesis took a narrative approach to the analysis of video diaries, generated through an affective methodology with seven Mexican men about their sexual-affective heterosexual relationships. The methodological process involved a relationship of ethics, friendship and co-production. Each of the seven men recorded themselves talking about their relationships, their partners and themselves in a uniquely vulnerable, honest and reflexive manner. The video diaries were then turned into seven narratives that were organised discursively into topics of: Emotions, Desire and Identity.  The analysis centred on affective practices, emotions, social mediations of desire and masculine identity as ongoing negotiations in a particular geopolitical context. The men in this study constantly situated themselves between the hegemonic discourse of masculinity in Mexico and alternatives closer to a feminist approach. This positioning showed how their practices and ideas, while still part of the hegemonic system, were also able to challenge it.  Thus, this thesis demonstrates the value of an affective methodology for working with men to analyse masculinities. The men who participated in this research revealed their daily navigations between multiple forms of masculinities and the hegemonic system still embedded in them. Such everyday negotiations highlight the very real challenges to be overcome in the movement towards more equal, free and ethical relationships between women and men.  Furthermore, by offering a situated study of how Mexican men negotiate their masculinity, this research contributes to broader Anglophone literature on masculinity, which tends to be rooted in the Anglo-American experience. While concerned with relatively privileged Mexican men, it shows how such men negotiate global stereotypes such as the macho, the provider, the lover or the rebel.  Finally, this thesis reveals how masculinities are manifested, as gender identity, with specific practices, desires, emotions and ways of being in the world; and also as a symbolic-material system of hierarchical organisation of sexed bodies. Thus, analysis of sexual-affective heterosexual relationships, through a focus on masculinities, can bring to light the contradictions and conflicts of being a man situated in a privileged position within the sex-gender system, in a social context that is increasingly questioning the position and the system that maintains it.</p>


2021 ◽  
Author(s):  
◽  
Ricardo Quirarte

<p>Studying men and masculinities in Mexico through feminist sociology is necessary to tackle gender inequalities. These inequalities can be as extreme as the institutional, sexual and physical violence that occur in disproportionate numbers, or as quotidian as the micro-machismos that go unnoticed as forms of everyday gender violence. It is paramount to understand masculinity as a system of domination and differentiation as well as a gender identity that is performed by bodies that feel, are affected and recognise themselves as masculine and as men. By doing so, the road towards equality will include a strong critique of how men have learned to pursue a certain form of masculinity.  To question men’s relation with masculinity and their experience of recognising themselves as such, this thesis took a narrative approach to the analysis of video diaries, generated through an affective methodology with seven Mexican men about their sexual-affective heterosexual relationships. The methodological process involved a relationship of ethics, friendship and co-production. Each of the seven men recorded themselves talking about their relationships, their partners and themselves in a uniquely vulnerable, honest and reflexive manner. The video diaries were then turned into seven narratives that were organised discursively into topics of: Emotions, Desire and Identity.  The analysis centred on affective practices, emotions, social mediations of desire and masculine identity as ongoing negotiations in a particular geopolitical context. The men in this study constantly situated themselves between the hegemonic discourse of masculinity in Mexico and alternatives closer to a feminist approach. This positioning showed how their practices and ideas, while still part of the hegemonic system, were also able to challenge it.  Thus, this thesis demonstrates the value of an affective methodology for working with men to analyse masculinities. The men who participated in this research revealed their daily navigations between multiple forms of masculinities and the hegemonic system still embedded in them. Such everyday negotiations highlight the very real challenges to be overcome in the movement towards more equal, free and ethical relationships between women and men.  Furthermore, by offering a situated study of how Mexican men negotiate their masculinity, this research contributes to broader Anglophone literature on masculinity, which tends to be rooted in the Anglo-American experience. While concerned with relatively privileged Mexican men, it shows how such men negotiate global stereotypes such as the macho, the provider, the lover or the rebel.  Finally, this thesis reveals how masculinities are manifested, as gender identity, with specific practices, desires, emotions and ways of being in the world; and also as a symbolic-material system of hierarchical organisation of sexed bodies. Thus, analysis of sexual-affective heterosexual relationships, through a focus on masculinities, can bring to light the contradictions and conflicts of being a man situated in a privileged position within the sex-gender system, in a social context that is increasingly questioning the position and the system that maintains it.</p>


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