CrystalExplorer is a native cross‐platform program supported on Windows, MacOS and Linux with the primary function of visualization and investigation of molecular crystal structures, especially ...through the decorated Hirshfeld surface and its corresponding two‐dimensional fingerprint, and through the visualization of void spaces in the crystal via isosurfaces of the promolecule electron density. Over the past decade, significant changes and enhancements have been incorporated into the program, such as the capacity to accurately and quickly calculate and visualize quantitative intermolecular interactions and, perhaps most importantly, the ability to interface with the Gaussian and NWChem programs to calculate quantum‐mechanical properties of molecules. The current version, CrystalExplorer21, incorporates these and other changes, and the software can be downloaded and used free of charge for academic research.
CrystalExplorer is a native cross‐platform program for the visualization and investigation of molecular crystal structures.
"The story is told by THE inventor-pioneer-master in the field and is accompanied by amazing illustrations... it will become an absolute reference and a best seller in chemistry!" Alberto Credi "... ...the great opus on the mechanical bond. A most impressive undertaking!" Jean-Marie Lehn Congratulations to co-author J. Fraser Stoddart, a 2016 Nobel Laureate in Chemistry.
In molecules, the mechanical bond is not shared between atoms-it is a bond that arises when molecular entities become entangled in space. Just as supermolecules are held together by supramolecular interactions, mechanomolecules, such as catenanes and rotaxanes, are maintained by mechanical bonds. This emergent bond endows mechanomolecules with a whole suite of novel properties relating to both form and function. They hold unlimited promise for countless applications, ranging from their presence in molecular devices and electronics to their involvement in remarkably advanced functional materials. The Nature of the Mechanical Bond is a comprehensive review of much of the contemporary literature on the mechanical bond, accessible to newcomers and veterans alike. Topics covered include: Supramolecular, covalent, and statistical approaches to the formation of entanglements that underpin mechanical bonds in molecules and macromolecules Kinetically and thermodynamically controlled strategies for synthesizing mechanomolecules Chemical topology, molecular architectures, polymers, crystals, and materials with mechanical bonds The stereochemistry of the mechanical bond (mechanostereochemistry), including the novel types of dynamic and static isomerism and chirality that emerge in mechanomolecules Artificial molecular switches and machines based on the large-amplitude translational and rotational motions expressed by suitably designed catenanes and rotaxanes. This contemporary and highly interdisciplinary field is summarized in a visually appealing, image-driven format, with more than 800 illustrations covering both fundamental and applied research. The Nature of the Mechanical Bond is a must-read for everyone, from students to experienced researchers, with an interest in chemistry's latest and most non-canonical bond. Read the Preface
The present study is focused on tubular multi-channel arrays composed of commercial fluoropolymer (FEP) tubes with different wall thickness. After proper charging in a high electric field, such ...tubular structures exhibit a large piezoelectric \{{\boldsymbol{d}}}_{{\bf{33}}}\ coefficient significantly exceeding the values of classical polymer ferroelectrics and being even comparable to conventional lead-free piezoceramics. The quasistatic piezoelectric \{{\boldsymbol{d}}}_{{\bf{33}}}\ coefficient was theoretically derived and its upper limits were evaluated considering charging and mechanical properties of the arrays. In order to optimize the \{{\boldsymbol{d}}}_{{\bf{33}}}\ coefficient the remanent polarization and the mechanical properties were taken into account, both being strongly dependent on the air channel geometry as well as on the wall thickness of the FEP tubes. The model predictions are compared with experimental d33 coefficients for two particular arrays with equal air gaps of 250 μm, but with different wall thickness of utilized FEP tubes of 50 μm and 120 μm, respectively. Analytical modeling allows for the prediction that arrays made of FEP tubes with a wall thickness of 10 μm are foreseen to exhibit a superb piezoelectric response of up to 600 pC/N if the height of stadium-like shaped air channels is reduced down to 50 μm, making them potentially interesting for application as highly sensitive sensors and energy harvesting.
This authoritative, widely cited book has been used all over the world. The Fourth Edition incorporates the latest developments in the field while maintaining the core objectives of previous ...editions: To correlate properties with chemical structure and to describe methods that permit the estimation and prediction of numerical properties from chemical structure, i.e. nearly all properties of the solid, liquid, and dissolved states of polymers.
•TIP-TIG was employed to achieve reliable welding of 20 mm thick TC4 alloy.•Mutually interlocked basket-weave microstructure is the key to joint strengthening.•Hot wire + swing process ensures the ...formation of the joint target microstructure.
In this study, narrow-gap hot wire vibrating tungsten inert gas arc welding (TIP-TIG) technology was employed to achieve reliable welding of 20 mm thick TC4 alloy plates. Microstructure and mechanical properties of different regions within the welded joint were particularly investigated. The results show that the heat-affected zone (HAZ) exhibited a typical bimodal microstructure consisting of equiaxial α phase, αʹ phase, and β phase. Meanwhile, the weld center showed a basket-weave pattern of α phase and β phase. Microhardness gradually decreased from the base metal towards the weld center, with an average microhardness of 315 HV0.2 at the weld center. The welded joints exhibited an average tensile strength of 1043 MPa, and all samples underwent ductile fracture.
•A holistic review of current research on the mechanical properties of AAC is provided.•The AACs reviewed include slag-based, fly ash-based, and fly ash/slag-based types.•Both static and dynamic ...mechanical properties of AAC are discussed.•The fracture, bond and high-temperature properties of AAC are also addressed.•The slag/fly ash ratio is a very influential factor to the mechanical properties of AAC.
Alkali-activated concretes (AACs) are attracting increasing attention due to their potential as alternatives to ordinary Portland cement concrete (OPCC). This paper is a holistic review of current research on the mechanical properties of AAC including research on its compressive strength, tensile strength, elastic modulus, Poisson’s ratio, stress–strain relationship under uniaxial compression, fracture properties, bond mechanism with steel reinforcement, dynamic mechanical properties, and high-temperature performance. Three types of AAC are reviewed: alkali-activated slag, alkali-activated fly ash, and alkali-activated slag-fly ash concretes. The applicability to AAC of design formulas found in codes of practice that were developed to estimate the basic mechanical performances of OPCC is also discussed. It is shown that, in general, AAC exhibits better bond performance with steel reinforcement and better strength performance after exposure to elevated temperatures than OPCC. For the other reviewed mechanical properties, the differences between AAC and OPCC largely depend on the proportions of raw materials in the concrete; specifically, the slag to fly ash ratio may be a very influential factor. As there is a trend to combine slag and fly ash in the production of AAC to achieve normal temperature curing and environmental friendliness, further research is deemed necessary to determine how the slag to fly ash ratio influences the fundamental mechanical properties of AAC and how this affects practical designs.
Open-cell Al-4.5Cu (wt.%) foams were produced by the replication casting technique in cell sizes of 2.00-2.38 and 3.35-4.75 mm. The fabricated foams were subjected to solution and aging treatments to ...assess the effect of such heat treatments on the microstructure and mechanical properties of the foams as a function of cell size. Solution and aging heat treatments were carried out at 535 °C for 5.5 h and 170 °C for 8 h, respectively. The porosity and relative density of all produced samples were estimated by He pycnometer. In addition, the average cell wall thickness was assessed by image analysis to correlate this variable with the response to heat treatments of the material. The microstructural evolution of the heat-treated samples was analyzed by means of scanning electron microscopy, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and differential scanning calorimetry. The mechanical characterization of the studied samples was carried out using uniaxial compression tests and microhardness tests. It was found that the foams did present different responses to both solution and aging treatments as a function of cell size, attributing these outcomes to the cell wall thickness variations, which presumably conditioned the cooling rates after heat treatments, thereby influencing the resulting microstructures and precipitation of Al-Cu second phases.
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