Effect of pyridyl donors from organic ligands versus metalloligands on material design

2021 ◽  
Author(s):  
Girijesh Kumar ◽  
Gulshan Kumar ◽  
Rajeev Gupta
Keyword(s):  
Material Design ◽  
Organic Ligands ◽  
The Impact ◽  
Coordination Frameworks

This review illustrates designs and structures of various coordination frameworks constructed using assorted organic ligands and metalloligands offering pyridyl donors to evaluate the impact of flexibility versus rigidity on material design.

scholarly journals The Effect of Cell Compression and Cathode Pressure on Hydrogen Crossover in PEM Water Electrolysis

2021 ◽  
Author(s):  
Agate Martin ◽  
Patrick Trinke ◽  
Markus Stähler ◽  
Andrea Stähler ◽  
Fabian Scheepers ◽  
...  
Keyword(s):  
Mass Transport ◽  
Cell Voltage ◽  
Water Electrolysis ◽  
Material Design ◽  
Operating Conditions ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Current Densities ◽  
Hydrogen Crossover ◽  
The Impact

Abstract Hydrogen crossover poses a crucial issue for polymer electrolyte membrane (PEM) water electrolysers in terms of safe operation and efficiency losses, especially at increased hydrogen pressures. Besides the impact of external operating conditions, the structural properties of the materials also influence the mass transport within the cell. In this study, we provide an analysis of the effect of elevated cathode pressures (up to 15 bar) in addition to increased compression of the membrane electrode assembly on hydrogen crossover and the cell performance, using thin Nafion 212 membranes and current densities up to 3.6 A cm-2. It is shown that a higher compression leads to increased mass transport overpotentials, although the overall cell performance is improved due to the decreased ohmic losses. The mass transport limitations also become visible in enhanced anodic hydrogen contents with increasing compression at high current densities. Moreover, increases in cathode pressure are amplifying the compression effect on hydrogen crossover and mass transport losses. The results indicate that the cell voltage should not be the only criterion for optimizing the system design, but that the material design has to be considered for the reduction of hydrogen crossover in PEM water electrolysis.

scholarly journals Understanding the Impact of Stent and Scaffold Material and Strut Design on Coronary Artery Thrombosis from the Basic and Clinical Points of View

2018 ◽  
Vol 5 (3) ◽  
pp. 71 ◽  
Author(s):  
Atsushi Sakamoto ◽  
Hiroyuki Jinnouchi ◽  
Sho Torii ◽  
Renu Virmani ◽  
Aloke Finn
Keyword(s):  
Material Design ◽  
Coronary Intervention ◽  
Radial Force ◽  
Late Time ◽  
Clinical Complications ◽  
Scaffold Thrombosis ◽  
Absorb Bvs ◽  
One Year ◽  
The Impact

The technology of percutaneous coronary intervention (PCI) is constantly being refined in order to overcome the shortcomings of present day technologies. Even though current generation metallic drug-eluting stents (DES) perform very well in the short-term, concerns still exist about their long-term efficacy. Late clinical complications including late stent thrombosis (ST), restenosis, and neoatherosclerosis still exist and many of these events may be attributed to either the metallic platform and/or the drug and polymer left behind in the arterial wall. To overcome this limitation, the concept of totally bioresorbable vascular scaffolds (BRS) was invented with the idea that by eliminating long-term exposure of the vessel wall to the metal backbone, drug, and polymer, late outcomes would improve. The Absorb-bioabsorbable vascular scaffold (Absorb-BVS) represented the most advanced attempt to make such a device, with thicker struts, greater vessel surface area coverage and less radial force versus contemporary DES. Unfortunately, almost one year after its initial approval by the U.S. Food and Drug Administration, this scaffold was withdrawn from the market due to declining devise utilization driven by the concerns about scaffold thrombosis (ScT) seen in both early and late time points. Additionally, the specific causes of ScT have not yet been fully elucidated. In this review, we discuss the platform, vascular response, and clinical data of past and current metallic coronary stents with the Absorb-BVS and newer generation BRS, concentrating on their material/design and the mechanisms of thrombotic complications from the pre-clinical, pathologic, and clinical viewpoints.

Analysis of a bicyclist’s head injury in lateral and frontal impact using the human full-body model

2017 ◽  
Vol 231 (3) ◽  
pp. 220-231 ◽  
Author(s):  
Tso-Liang Teng ◽  
Cho-Chung Liang ◽  
Van-Hai Nguyen
Keyword(s):  
Brain Injuries ◽  
Tangential Velocity ◽  
Material Design ◽  
Normal Velocity ◽  
Test Procedures ◽  
Bicycle Helmets ◽  
General Terms ◽  
Impact Protection ◽  
The Impact ◽  
Full Body

Helmets reduce the frequency and severity of head and brain injuries resulting from bicycle crashes. To ensure that all bicycle helmets provide a certain level of effectiveness, helmets are required to satisfy certain standards of construction and material design before they can be sold in the market. Impact protection is the primary consideration of nearly every helmet standard. The general terms for a test for assessing impact protection involve shock absorption. A helmeted headform is dropped onto an anvil and the headform acceleration is measured. However, the test procedures of the existing standards do not properly assess the protection level of helmets against oblique impacts. To investigate bicycle helmets in a real accident scenario, this study simulated the full body of a bicyclist when free falling onto a road. This study considered the normal velocity (VN) of 5.66 m/s and tangential velocity (VT) values of 0, 5, and 10 m/s. Finite element analyses of helmet impact tests were conducted using LS-DYNA software. Moreover, the impact responses obtained using full-body and detached-headform models were compared under identical impact conditions. The analysis results obtained herein can be useful for evaluating helmet quality and guiding future developments in helmet innovation.

scholarly journals Lattice thermal transport in two-dimensional alloys and fractal heterostructures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aravind Krishnamoorthy ◽  
Nitish Baradwaj ◽  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Lattice Thermal Conductivity ◽  
Material Design ◽  
Two Dimensional ◽  
Scale Free ◽  
Dopant Atoms ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations ◽  
The Impact

AbstractEngineering thermal transport in two dimensional materials, alloys and heterostructures is critical for the design of next-generation flexible optoelectronic and energy harvesting devices. Direct experimental characterization of lattice thermal conductivity in these ultra-thin systems is challenging and the impact of dopant atoms and hetero-phase interfaces, introduced unintentionally during synthesis or as part of deliberate material design, on thermal transport properties is not understood. Here, we use non-equilibrium molecular dynamics simulations to calculate lattice thermal conductivity of $${\mathrm {(Mo|W)Se_2}}$$ ( Mo | W ) Se 2 monolayer crystals including $${\mathrm {Mo}}_{1-x}{\mathrm {W}}_x{\mathrm {Se_2}}$$ Mo 1 - x W x Se 2 alloys with substitutional point defects, periodic $${\mathrm {MoSe_2}|\mathrm {WSe_2}}$$ MoSe 2 | WSe 2 heterostructures with characteristic length scales and scale-free fractal $${\mathrm {MoSe_2}}|{\mathrm {WSe_2}}$$ MoSe 2 | WSe 2 heterostructures. Each of these features has a distinct effect on phonon propagation in the crystal, which can be used to design fractal and periodic alloy structures with highly tunable thermal conductivities. This control over lattice thermal conductivity will enable applications ranging from thermal barriers to thermoelectrics.

scholarly journals Role of colour in ecological approach to product and material design

2021 ◽  
Vol 26 (3) ◽  
pp. 33-41
Author(s):  
Soňa Otiepková
Keyword(s):  
Material Design ◽  
Product Evaluation ◽  
Research Paper ◽  
Point Of View ◽  
Human Interaction ◽  
Ecological Context ◽  
Fixed Boundaries ◽  
The Impact

Abstract The aim of this research paper is to map, document and classify new, progressive and perspective approaches to colour in product and material design. The purpose is to identify the impact and importance of colour in the creation of new materials and products from an ecological point of view. The majority of current progressive approaches to design creation and research is set in an ecological framework, taking into account their impact on the environment. The question is not whether colour is present in this process, but rather where it stands in this process, whether it can help it and how much it affects it. One of the objectives of this article is to raise awareness in this area and to arouse interest in and discussion on this topic. The theme of colours in design is often overlooked and relegated to the background. The results of several scientific studies on the impact of colour on product evaluation and consumer shopping behaviour suggest the potential of this topic and open up space for further research. In this research paper, we consider the approach of product and material designers and researchers to colour in an ecological context, as a stand-alone design and material creation group. Within this main group, individual approaches can be classified into four basic principles, which the paper defines and describes. They are analysed and researched in more depth through specific examples of the work of various designers. The principles have no fixed boundaries, they are not isolated. They influence or follow each other. This classification of the approach to colour in an ecological context allows us primarily to talk about it more professionally and attempt to define its importance and role in individual approach. Ultimately, it helps us answer the question of whether and how colour can affect the process of changing human interaction with the environment.

scholarly journals Sulfidization of ferrihydrite in the presence of organic ligands

2021 ◽  
Author(s):  
Laurel K. ThomasArrigo ◽  
Sylvain Bouchet ◽  
Ralf Kaegi ◽  
Ruben Kretzschmar
Keyword(s):  
Trace Elements ◽  
High Surface ◽  
Organic Ligand ◽  
Organic Ligands ◽  
Molar Ratios ◽  
Iron Mineral ◽  
Surface Areas ◽  
Secondary Reactions ◽  
Mineral Components ◽  
The Impact

<p>In soils and sediments, short-range order (SRO) iron minerals constitute one of the most abundant and reactive mineral components. With high surface areas and points of zero charge near pH 7-8, SRO minerals like ferrihydrite (Fe<sub>10</sub>O<sub>14</sub>(OH)<sub>2</sub>+mH<sub>2</sub>O) are often linked to high adsorption of nutrients (C, N, P, S) and trace elements (e.g. As, Zn). However, under oxygen-limiting conditions, microbially derived sulfide (S(−II)) may cause the rapid reductive dissolution of ferrihydrite and the release of associated nutrients and trace elements, thus influencing the biogeochemical cycling of trace elements and nutrients, particularly in redox dynamic environments.</p><p>Sulfidization of ferrihydrite occurs rapidly, whereby electron transfer between surface complexed sulfide and the ferrihydrite surface results in (partially) oxidized sulfur species and Fe(II). Depending on the S(-II):Fe molar ratios, secondary reactions then lead to mackinawite (FeS) or pyrite (FeS<sub>2</sub>) precipitation. In nature, however, ferrihydrite is often found associated with natural organic matter (NOM). Because coprecipitation of ferrihydrite with NOM decreases particle size, alters the surface charge, and may block surface sorption sites, we speculated that kinetics and pathways of sulfidization of organic-associated ferrihydrite may differ from those of the pure mineral. Therefore, in this study, we followed iron mineral transformations and sulfur speciation during sulfidization of a pure ferrihydrite over one year and compared this to ferrihydrite coprecipitated with model organic ligands (polygalacturonic acid, galacturonic acid, and citric acid). Using a combination of solid- and aqueous phase Fe and S speciation techniques, we show that the impact of OM on ferrihydrite sulfidization kinetics and pathways varies with the chemical structure of the organic ligand, and that secondary reactions continue well past the initial rapid consumption of S(-II).</p>

scholarly journals Shape-dependent effective diffusivity in packings of hard cubes and cuboids compared with spheres and ellipsoids

Soft Matter ◽  
2017 ◽  
Vol 13 (46) ◽  
pp. 8864-8870 ◽  
Author(s):  
Magnus Röding
Keyword(s):  
Granular Material ◽  
Effective Diffusivity ◽  
Material Design ◽  
Computational Screening ◽  
The Impact

We performed computational screening of effective diffusivity in cube and cuboid systems, elucidating the impact of shape on the granular material design.

Blast Resistant Elastomeric Polymer-by-Design

2011 ◽  
Author(s):  
Kristin L. Schaaf ◽  
Sia Nemat-Nasser
Keyword(s):  
Composite Materials ◽  
Constitutive Relations ◽  
Material Design ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Material System ◽  
Scanning Calorimetry ◽  
Characterization Methods ◽  
Dynamic Mechanical ◽  
The Impact

The essence of this research is to mitigate shock through material design. Here we seek to develop a thorough understanding of the material through experimental characterization methods that lend themselves to creating verifiable constitutive relations, all while working towards the development of a new blast resistant elastomeric composite material. The host elastomer, polyurea, is created by reacting Versalink P-1000 with Isonate 143L. This study evaluates the impact of both chemistry modifications and the integration of micro-scale additives on the polyurea material system properties and performance. The properties of the resultant elastomers and elastomeric composite materials are mechanically and thermally characterized using durometer testing, dynamic mechanical analysis (DMA) testing, and differential scanning calorimetry (DSC) testing in order to determine the hardness, storage and loss moduli, and glass transition temperature of the composites, respectively. Preliminary results indicate that the durometer and dynamic mechanical properties of the material can be significantly altered through such modifications. The work described here is part of an ongoing effort to develop and verify rules and tools for creating elastomer-based composite materials with optimally designed compositions and characteristics.

A series of coordination polymers based on varied polycarboxylates and different imidazole-containing ligands: syntheses, crystal structures and physical properties

RSC Advances ◽  
2015 ◽  
Vol 5 (98) ◽  
pp. 80457-80471 ◽  
Author(s):  
Xiao-Feng Wang ◽  
Min Yu ◽  
Guang-Xiang Liu
Keyword(s):  
Physical Properties ◽  
Crystal Structures ◽  
Hydrothermal Method ◽  
Coordination Polymers ◽  
Organic Ligands ◽  
Coordination Frameworks

To investigate the effect of organic ligands on the coordination frameworks, seven nickel(ii) coordination polymers, based on varied polycarboxylates and different imidazole-containing ligands, are synthesized under hydrothermal method.

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