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In this chapter, viscoelasticity effects in composites are studied. Three-dimensional CGs with linear viscoelastic matrices, containing linearly elastic spherical inclusions with or without interphases/coatings are treated. For each CG, the independent displacement fields are developed by the characteristic-length-scaled Papkovich-Neuber solutions and spherical harmonics. A compatible boundary displacement field is also assumed with Wachspress coordinates as nodal shape functions on each of the polygonal faces. Multi-field boundary variational principles are used to develop the CG stiffness matrices. After the establishment of CGs in Laplace transform domain, the homogenized and localized responses are transformed back to the time domain using the Zakian technique. With different kinds of models to describe the property of the viscoelastic polymers, the generated homogenized moduli and localized stress distributions are validated against the experimental data, simulations by commercial FE software, and predictions by composite spherical assemblage models. Parametric studies are also carried out to investigate the influence of material and geometric parameters on the behavior of viscoelastic composites. Finally, the viscoelastic CGs are also used to study the effect of the negative Young’s modulus of particles on the stability and loss tangent of viscoelastic composites.
This chapter discusses some general algorithms which are useful in the computational homogenization using the Computational Grains (CGs) method. First, an algorithm for generating a statistically equivalent representative volume element (SERVE) is presented. Then, an algorithm to divide the SERVE in to Voronoi cells (polygons in 2D and polyhedrons in 3D), and using a CG in each Voronoi cell is discussed. The role of parallel computation is also discussed.
In this chapter, a new kind of Computational Grain (CG) with embedded cylindrical elastic fibers is developed for the micromechanical modeling of fiber-reinforced composites. The trial displacement fields within the CGs are assumed using Papkovich-Neuber solutions. Cylindrical harmonics scaled by characteristic lengths are employed as the P-N potentials. A compatible displacement field is assumed at elemental surfaces and fiber–matrix interfaces, and the stiffness matrices of CGs are derived by a newly developed multi-field boundary variational principle.
Through numerical simulations, we demonstrate that the developed CGs have high computational efficiency, and they can accurately capture the localized stress distributions under various loadings. Computational Grains are also effective for estimating the effective material properties of fiber-reinforced composites, as validated by comparing with experimental results in the literature. Moreover, with the use of parallel computation, the time required for CGs is significantly decreased. Thus, we consider that the kind of CGs developed in this study is an accurate and efficient tool for the micromechanical modeling of fiber composites. Such a tool of micromechanical modeling can also be combined with meso- and macro-scale finite elements for the multi-scale analysis of laminates and composite parts, which will be given in Chapter 12.
By rearranging the weakly singular boundary, integral equations developed by Han and Atluri, an SGBEM-CG, which is abbreviated as CG, is developed in this chapter. The CG, representing a single grain of a material, can include arbitrarily shaped voids, inclusions (of a different material), and microcracks. The CG has a stiffness matrix and a load vector, which have similar physical meanings to the traditional displacement FEM. The stiffness matrix is symmetric, positive-definite, and has the same number of rigid-body modes. Different CGs, each with different isotropic material properties, can be directly coupled by the assembly procedure, and are used to directly and efficiently model the microstructure of heterogeneous composite materials. Some examples are also presented, with microcracks interacting with inclusions and holes. This provides some insight of a possible future study of the micro-cracking and damage of heterogeneous material. By introducing stochastic variations of the shapes of CG, and stochastic variations of the properties of the constituent materials, the realistic statistical bounds on the overall properties of composite materials will be determined in future studies.
This study estimated the treatment cost of pediatric abdominal tuberculosis that potentially needs surgical treatment in India. Data were collected from 38 in-patient children at Christian Medical Hospital, Ludhiana as part of a clinical study conducted to establish the patterns of presentation and outcomes of abdominal tuberculosis in an Indian setting. A bottom-up approach was used to estimate the costs from a healthcare provider perspective, and a generalized linear model (GLM) was run to find variables that had an impact on the costs. Costs were reported in international dollars ($) and India Rupees (INR). The results show that the average direct cost was $3095.00 (standard deviation [SD]: 3480.82) or 68,065.13 INR (SD: 76,539.69). The GLM results established that duration of treatment and surgical treatment were significantly associated with higher costs. Efforts of eliminating the condition should be strengthened.
Introduced in 2020, the notion of living artefacts encompasses biodesign outcomes that maintain the vitality of organisms such as fungi, algae, bacteria, and plants in the use of everyday artefacts, enabling new functions, interactions, and expressions within our daily lives. This paper situates living artefacts at the intersection of the sustainability discourse and more-than-human ontologies, illuminating the unprecedented opportunities that living artefacts present for regenerative ecologies. These ecologies are characterized by a fundamental inclination toward mutualism, creativity, and coevolution. In regenerative ecologies, the human-nature relationship transcends the binary distinction and it manifests as a single autopoietic system in which the constituent members collaboratively engage in the creation, transformation, and evolution of shared habitats. The paper outlines five pillars, supplemented by guiding questions and two illustrative cases, to aid designers in unlocking, articulating, and critically evaluating the potential of living artefacts for regenerative ecologies.
(S)-α-Ethyl-2-oxo-1-pyrrolidineacetamide (trade name levetiracetam), a derivative of piracetam, is used clinically as an add-on treatment for partial-onset seizures. In this study, we report the solid-state structure of a new drug co-crystal produced from levetiracetam and 3,5-dinitrosalicylic acid through cooling crystallization. This compound was further characterized by infrared spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction. The new co-crystals show a 1:1 stoichiometry and crystallize in the monoclinic system, space group P21, with cell parameters: a = 9.7709(3) Å, b = 6.2202(2) Å, c = 14.7280(4) Å, α = 90°, β = 96.0340(10)°, γ = 90°, V = 890.16(5) Å3, and Z = 2. It is identified that hydrogen bonds are the main interactions between levetiracetam and 3,5-dinitrosalicylic acid, and the contribution of each hydrogen bond in maintaining the stability of the crystal structure was also quantified using Hirshfeld surface analysis.
This is the first book that systemically introduces the theory and implementation of Computational Grains for micromechanical modeling of heterogeneous materials. This book covers the specifically designed mathematics embedded in Computational Grains, and the entire process of microstructure construction, tessellation, CG simulation and homogenization. The Computational Grains discussed in this book consider elastic, non-elastic, and multi-physics solids. Materials damage development are also preliminarily discussed, with CGs considering matrix-inclusion debonding as well as embedded microcracks. Presenting the theory step-by-step and with detailed examples and MATLAB codes, the material is accessible and practical for readers. This will be ideal for graduate students and researchers in mechanical and aerospace engineering and applied mechanics.
A new compound NH4Co2OH(MoO4)2⋅H2O was prepared by precipitation of aqueous solutions of cobalt nitrate and ammonium heptamolybdate at pH = 7.5. The crystal structure was identified by X-ray powder diffraction (XRPD) and Rietveld refinement as a known polymorph of layered molybdates (Φy) with general formula AT2OH(MoO4)2⋅H2O (A = NH4+, Na+, K+ and T = Zn2+, Co2+, Cu2+, Ni2+) and refined from a model based on that structure. The lattice parameters were refined with R-3 space group (148) a = 6.1014(2) Å, b = 6.1014(2) Å, c = 21.826(1) Å, α = 90°, β = 90°, and γ = 120°.
Shape-memory polymers can be used to develop thermoresponsive programmable materials that can take on sensory and actuator tasks as their ambient temperature changes. In this contribution, a self-synthesised poly(1,10-decylene adipate) diol-based polyester urethane (PEU) was used for their fabrication. After processing the PEU into filaments, programmable materials, including a gear-like object, the teeth of a ‘bevel gear’ and a unit cell, were additively manufactured by fused filament fabrication. In any case, a thermomechanical treatment was conducted that involved the deformation of the polymer at 75°C. After cooling to 15°C, the programmable materials were unloaded and the thermoresponsiveness between 23°C and 58°C was investigated. A maximum thermoreversible change in height of about 39% was detected for the ‘gear’. With regard to the ‘bevel gear’, proof of feasibility was provided for use as overheating protection, so that a force transmission could be switched off when heated and switched on when cooled down. The unit cell actuated under a weak external load of 0.01 N, thus exhibiting thermoreversible length changes of about 45%.
Biotechnology Design is a question-led journal. All our contributions should relate to and help answer one of our questions. But how do we know if we are asking the right questions? What if we are missing a new piece of science, new concept, new challenge, or a new biotechnology idea that does not match one of our questions. Could this new idea lead to new questions? This is the space for these new ideas. We especially welcome contributions from early-stage research which combines early experimentation and scientific data with a new idea, challenge of application domain. These papers may ultimately be seeds for new questions, contributions to our non-peer review ‘Community Section’ which will develop over time to become full papers. As with all contributions to Biotechnology Design these contributions should be question-led and, as contributions to our ‘New Seeds?’ theme do not connect to an existing question, the question being answered should be clearly stated.
The built environment contributes to global carbon dioxide emissions with carbon-emitting building materials and construction processes. While achieving carbon-neutral construction is not feasible with conventional construction methods, microbial-based construction processes were suggested over three decades ago to reduce carbon dioxide emissions. With time, questions regarding scaling, predictability, and the applicability of microbial growth and biomass production emerged and still needed to be resolved to allow manufacturing. Within this opinion, we will discuss what can be achieved not to ‘grow a building’ per se but to ‘grow environmentally friendly biocement’. Elaborate pathways leading to the formation of cementitious materials by genetically manipulatable microorganisms have been described so far, providing options to enhance the suitability of these pathways for construction with synthetic biology and bioconvergence. These processes can also be combined with additional beneficial properties of cement-producing organisms, such as antimicrobial properties and carbon fixation by photosynthesis. Therefore, while we cannot yet ‘grow a building’, we can grow and design biocement for the construction industry.
The crystal structure of danofloxacin mesylate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Danofloxacin mesylate crystallizes in space group P1 (#1) with a = 6.77474(8), b = 12.4973(4), c = 12.82826(28) Å, α = 84.8709(29), β = 87.7501(10), γ = 74.9916(4)°, V = 1044.723(11) Å3, and Z = 2. The protonation of the danofloxacin cations was established by the analysis of potential intermolecular interactions and differs from that expected from isolated-cation calculations. The crystal structure consists of alternating layers of cations and anions parallel to the ac-plane. There is parallel stacking of the oxoquinoline rings along the a-axis. The expected N–H⋯O hydrogen bonds between the cations and anions are not present. Each cation makes an N–H⋯O hydrogen bond with the other cation, resulting in zig-zag chains along the a-axis. Both cations have strong intramolecular O–H⋯O hydrogen bonds. There are several C–H⋯O hydrogen bonds between the danofloxacin cations and mesylate anions. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).
A new polymorphic form of sodium selenite pentahydrate is reported in this contribution. We determined its crystal structure from laboratory powder diffraction data recorded at room temperature. It crystallizes in the monoclinic system P21/n with Z = 4. The lattice parameters are a = 15.01473(16) Å, b = 7.03125(7) Å, c = 8.13336(10) Å, β = 98.4458(10)°, and V = 849.345(16) Å3. The crystal structure exhibits a layered structure with isolated 1D chains running along the b-axis.
The biotechnology design (biodesign) enterprise is reshaping our relationship with nature and requires broad public engagement for innovative and ethical development. However, current biodesign programs are often limited to formal education settings such as universities, community colleges, and high schools. To grow deeper networks with and among communities that are often excluded, we need new approaches and learning spaces. These must expand the diversity of voices that frame biodesign questions and drive when, where, and how we practice biotechnology design. Through our work, we have found that community-based biodesign spaces (informal learning spaces) can empower multidirectional and multigenerational knowledge exchange and advance a more diverse, inclusive, and innovative biodesign enterprise. In this article, we illustrate the benefits of a biodesign education ecosystem through case studies of three learning spaces: (1) a community bio laboratory, (2) an educational summer camp, and (3) an art-based maker space. This informal educational ecosystem brings together artists, educators, activists, and researchers to elevate ancestral science knowledge, creativity, play, and storytelling as central to biodesign education. While each is important independently, emergent power comes from connections between community biotechnology design spaces. By highlighting successful approaches used across these spaces, our three case studies show how diverse community engagement can sustain a vibrant biodesign ecosystem. Our findings can inform existing biodesign approaches and broaden their impact to grow a more innovative, relevant, and accountable biodesign enterprise.
We prove that certain differential operators of the form $ DLD $ with $ L $ hypergeometric and $ D=z\frac{\partial }{dz} $ are of Picard–Fuchs type. We give closed hypergeometric expressions for minors of the biextension period matrices that arise from certain rank 4 weight 3 Calabi–Yau motives presumed to be of analytic rank 1. We compare their values numerically to the first derivative of the $ L $-functions of the respective motives at $ s=2 $.