Regulating the structural dimensionality and dynamic properties of a porous dysprosium coordination polymer through solvent molecules

2020 ◽  
Vol 7 (4) ◽  
pp. 930-938
Author(s):  
Fang Ma ◽  
Rong Sun ◽  
Ai-Huan Sun ◽  
Jin Xiong ◽  
Hao-Ling Sun ◽  
...  

The solvent molecules can regulate the structural dimensionality of a porous dysprosium coordination polymer from three to two and its dynamic behavior, as evidenced by the increase of the effective energy barriers and slowdown of quantum tunneling.

2015 ◽  
Vol 71 (8) ◽  
pp. m148-m149
Author(s):  
Mohammad Iqbal ◽  
James Raftery ◽  
Peter Quayle

The title copper(II) complex, {(C27H37N2)[Cu4(CH3COO)8Cl]·3CH2Cl2}n, is a one-dimensional coordination polymer. The asymmetric unit is composed of a copper(II) tetraacetate paddle-wheel complex, a Cl−anion situated on a twofold rotation axis, half a 1,3-bis(2,6-diisopropylphenyl)imidazolium cation (the whole molecule being generated by twofold rotation symmetry) and one and a half of a dichloromethane solvent molecule (one being located about a twofold rotation axis). The central metal-organic framework comprises of a tetranuclear copper(II) acetate `paddle-wheel' complex which arises from the dimerization of the copper(II) tetraacetate core comprising of three μ2-bidentate acetate and one μ3-tridentate acetate ligands per binuclear paddle-wheel complex. Both CuIIatoms of the binuclear component adopt a distorted square-pyramidal coordination geometry (τ = 0.04), with a Cu...Cu separation of 2.6016 (2) Å. The apical coordination site of one CuIIatom is occupied by an O atom of a neighbouring acetate bridge [Cu—O = 2.200 (2) Å], while that of the second CuIIatom is occupied by a bridging chloride ligand [Cu...Cl = 2.4364 (4) Å]. The chloride bridge is slightly bent with respect to the Cu...Cu internuclear axis [Cu—Cl—Cu = 167.06 (6)°] and the tetranuclear units are located about a twofold rotation axis, forming the one-dimensional polymer that propagates along [101]. Charge neutrality is maintained by the inclusion of the 1,3-bis(2,6-diisopropylphenyl)imidazolium cation within the crystal lattice. In the crystal, the cation and dichloromethane solvent molecules are linked to the coordination polymer by various C—H...O and C—H...Cl hydrogen bonds. There are no other significant intermolecular interactions present.


Author(s):  
Heather L. Lai ◽  
Cuiyu Kuang ◽  
Jared Nelson

The development of flexible, viscoelastic materials for consumer 3D printers has provided the opportunity for a wide range of devices with damping behavior such as tuned vibration isolators to be innovatively developed and inexpensively manufactured. However, there is currently little information available about the dynamic behavior of these 3D printed materials necessary for modeling of dynamic behavior prior to print. In order to fully utilize these promising materials, a deeper understanding of the material properties, and the subsequent dynamic behavior is critical. This study evaluates the use of three different types of models: transient response, frequency response and hysteretic response to predict the dynamic behavior of viscoelastic 3D printed materials based on static and dynamic material properties. Models of viscoelastic materials are presented and verified experimentally using two 3D printable materials and two traditional viscoelastic materials. The experimental response of each of the materials shows agreement with the modeled behavior, and underscores the need for improved characterization of the dynamic properties of viscoelastic 3D printable materials.


Author(s):  
Lin Wang ◽  
Qiao-Yun Qin ◽  
Fan Zhang ◽  
Cheng-Wen Tan

Abstract Magnesium alloy is very attractive in many industrial applications due to its low density. The structure-property relationships of the magnesium alloy under quasi-static loading have been extensively investigated. However, the dynamic behavior, particularly the mechanism of high-rate plastic deformation, of the magnesium alloy requires more in-depth investigations. In this paper, the effect of aging treatment on the quasi-static and dynamic properties of a typical rare earth Mg-Gd-Y magnesium alloy is investigated. In particular, the plastic deformation mechanism under dynamic compression loading is discussed. Split Hopkinson Pressure Bar (SHPB) was used to carry out dynamic compression tests with controllable plastic deformation by using stopper rings. The experimental results demonstrate that both static and dynamic properties of the Mg-Gd-Y alloy vary under various aging treatment conditions (under-aged, peak-aged and over-aged conditions), due to two different kinds of second phases: remnant micro size phase from solid solution treatment and nano precipitation from aging treatment. The results of microstructure characterization and statistic analysis of the metallographic phase are presented. The area fraction of the twinned grains increases due to aging treatment and dynamic loading. The main plastic deformation mechanism of the rare earth Mg-Gd-Y magnesium alloy is possibly dislocation slip, rather than twinning for the conventional AZ31 magnesium alloy under high strain rate loading.


Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4583
Author(s):  
Shailendra Rajput ◽  
Alon Kuperman ◽  
Asher Yahalom ◽  
Moshe Averbukh

The specific power storage capabilities of double-layer ultracapacitors are receiving significant attention from engineers and scientific researchers. Nevertheless, their dynamic behavior should be studied to improve the performance and for efficient applications in electrical devices. This article presents an infinite resistor–capacitor (r–C) chain-based mathematical model for the analysis of double layer ultracapacitors. The internal resistance and capacitance were measured for repetitive charging and discharging cycles. The magnitudes of internal resistance and capacitance showed approximately ±10% changes for charge-discharge processes. Electrochemical impedance spectroscopy investigations revealed that the impedance of a double-layer ultracapacitor does not change significantly in the temperature range of (−30 °C to +30 °C) and voltage range of (0.3376–2.736 V). The analysis of impedance data using the proposed mathematical model showed good agreement between the experimental and theoretical data. The dynamic behavior of the ultracapacitor was successfully represented by utilizing the proposed infinite r–C chains equivalent circuit, and the reverse Fourier transform analysis. The r–C electrical equivalent circuit was also analyzed using the PSIM simulation software to study the dynamic behavior of ultracapacitor parameters. The simulation study yields an excellent agreement between the experimental and calculated voltage characteristics for repetitive charging-discharging processes.


Author(s):  
Hang-Ju Zhao ◽  
Jian-Ping Ma ◽  
Qi-Kui Liu ◽  
Yu-Bin Dong

A new 1,3,4-oxadiazole-containing bispyridyl ligand, namely 5-(pyridin-4-yl)-3-[2-(pyridin-4-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione (L), has been used to create the novel complexes tetranitratobis{μ-5-(pyridin-4-yl)-3-[2-(pyridin-4-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione}zinc(II), [Zn2(NO3)4(C14H12N4OS)2], (I), andcatena-poly[[[dinitratocopper(II)]-bis{μ-5-(pyridin-4-yl)-3-[2-(pyridin-4-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione}] nitrate acetonitrile sesquisolvate dichloromethane sesquisolvate], {[Cu(NO3)(C14H12N4OS)2]NO3·1.5CH3CN·1.5CH2Cl2}n, (II). Compound (I) presents a distorted rectangular centrosymmetric Zn2L2ring (dimensions 9.56 × 7.06 Å), where each ZnIIcentre lies in a {ZnN2O4} coordination environment. These binuclear zinc metallocycles are linked into a two-dimensional network through nonclassical C—H...O hydrogen bonds. The resulting sheets lie parallel to theacplane. Compound (II), which crystallizes as a nonmerohedral twin, is a coordination polymer with double chains of CuIIcentres linked by bridgingLligands, propagating parallel to the crystallographicaaxis. The CuIIcentres adopt a distorted square-pyramidal CuN4O coordination environment with apical O atoms. The chains in (II) are interlinkedviatwo kinds of π–π stacking interactions along [0\overline 11]. In addition, the structure of (II) contains channels parallel to the crystallographicadirection. The guest components in these channels consist of dichloromethane and acetonitrile solvent molecules and uncoordinated nitrate anions.


2013 ◽  
Vol 69 (10) ◽  
pp. 1100-1103
Author(s):  
Sizwe J. Zamisa ◽  
Patrick Ndungu ◽  
Bernard Omondi

The reaction of 4,4′-bipyridine with copper acetate in the presence of 4-nitrophenol led to the formation of the title compound, {[Cu(CH3COO)2(C10H8N2)]·C6H5NO3·2H2O}n. The complex forms a double-stranded ladder-like coordination polymer extending along thebaxis. The double-stranded polymers are separated by 4-nitrophenol and water solvent molecules. The two CuIIcentres of the centrosymmetric Cu2O2ladder rungs have square-pyramidal coordination environments, which are formed by two acetate O atoms and two 4,4′-bipyridine N atoms in the basal plane and another acetate O atom at the apex. The ladder-like double strands are separated from each other by one unit-cell length along thecaxis, and are connected by the water and 4-nitrophenol molecules through a series of O—H...O and C—H...O hydrogen-bonding interactions and two unique intermolecular π–π interactions.


2015 ◽  
Vol 76 (8) ◽  
Author(s):  
A. I. Yusuf ◽  
M. A. Norliyati ◽  
M. A. Yunus ◽  
M. N. Abdul Rani

Elastomeric bearing is a significant device in structures such as in bridges and buildings. It is used to isolate the ground structure (substructure) and the above ground structure (superstructure) from seismic loads such as earthquake load. Understanding the dynamic behavior of the elastomeric bearing in terms of natural frequencies, mode shapes and damping are increasingly important especially in improving the design and the failure limit of the elastomeric bearing. Modal analysis is one of the methods used to determine the dynamic properties of any materials. Hence, the main objective of this research is to determine the dynamic properties of elastomeric bearing components in terms of natural frequencies, mode shapes, and damping via numerical and experimental modal analysis. This method had been successfully performed in investigating the dynamic behavior of rubber and steel shim plate.


2004 ◽  
Vol 33 (6) ◽  
pp. 648-649 ◽  
Author(s):  
Keiichi Adachi ◽  
Sumio Kaizaki ◽  
Koichi Yamada ◽  
Susumu Kitagawa ◽  
Satoshi Kawata

Author(s):  
Saeid Dousti ◽  
Paul Allaire ◽  
Bradley Nichols ◽  
Jianming Cao ◽  
Timothy Dimond

In this paper, the extended Reynolds equation proposed by Dousti et al. [1] is applied to predict the dynamic behavior of different fixed geometry bearings used in vertical water pumps. The influence of convective and temporal inertia effects is studied in regular and preloaded multi-lobe bearings. It is shown that the convective inertia is more influential at the presence of preload and higher rotational speeds and alters the stiffness and damping properties of the bearing. The temporal inertia leads to the prediction of considerable lubricant added mass coefficients in the order of journal mass. The stability analysis shows depending upon the geometry of the bearing, the new extended Reynolds equation may predict higher or lower logarithmic decrement.


2019 ◽  
Vol 19 (12) ◽  
pp. 1950154
Author(s):  
Yan-An Gao ◽  
Qing-Shan Yang ◽  
Yun Dong ◽  
Chao Chen ◽  
Tao-Ping Ye

This study comprehensively explores the dynamic behavior of a slender slab due to the excitation of pedestrian traffic. Three kinds of excitation models are adopted to describe the vibration of the slab induced by pedestrians. A comparison of the structural responses shows that the bipedal model results in larger vibrations than the mass–spring–damper or pseudo-excitation models. Further research indicates that the pedestrians evidently alter the dynamic properties of the slab by affecting its frequency and damping capacity. The slab tends to be more flexible at a lower frequency as the pedestrian walks across its surface while its damping capacity is improved. In contrast, the slab can increase the frequency, while decreasing the damping of the pedestrian model. Thus, the slab also alters the properties of the pedestrians. In addition, an investigation of the bipedal model parameters indicates that the variations of the leg stiffness, damping, and body mass have distinct effects on the slab characteristics and vibrations. In order to assess the response of the slab to a crowd, a new simplified theory is introduced to describe the dynamic properties of the slab under multi-layout excitations, including human influences resulting from different body properties. The results of this study provide potential ways for understanding the vibratory mechanisms of slender structures such as footbridges, grandstands, or stations under crowd excitations.


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