Instrumented indentation tests using both constant loading rate (CLR) and continuous stiffness measurement (CSM) operation modes were performed to investigate the deformation mechanism and their sensitivity to the deformation rate in semi-crystalline polymers through the quantitative analysis of load-depth loading and unloading curves. The strain rate was constant during the CSM tests, while the strain rate decreased with the increasing of loading time in CLR tests. The mechanical response mechanism of the semi-crystalline polymers to these tests was very complicated because of the combined effects of strain-hardening in the crystal phase and strain-softening in the amorphous phase. Results show that the loading index m reflects the strain-hardening or strain-softening response during indentation. When m > 2, the mechanical response was due to the strain-hardening, and when m < 2, the response was due to strain-softening. A method based on the measured contact hardness was proposed to obtain the unloading stiffness, and the other mechanical parameters could then be determined according to the unloading stiffness. 相似文献
Two Ag(I)-based coordination polymers, namely [Ag2(3,3′-tmbpt)(o-Hbdc)2]·H2O (1) and [Ag8(3,3′-tmbpt)4(1,2,4-Hbtc)4(H2O)] (2) (3,3′-tmbpt?=?1-((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole, o-H2bdc?=?1,2-benzenedicarboxylic acid and 1,2,4-H3btc?=?1,2,4-benzenetricarboxylic acid), have been synthesized. Single-crystal X-ray diffraction analyses, elemental analyses, infrared spectra, powder X-ray diffraction analyses and thermogravimetric analyses have been carried out to characterize the structures of 1 and 2. Compound 1 shows a (3,4)-connected 2D layered structure with a Schläfli symbol of (42·6)(42·63·8). The intermolecular O–H···O hydrogen-bonding interactions extend the 2D layer into a 3D supramolecular architecture. Compound 2 exhibits a (3,3)-connected double-layered structure with a Schläfli symbol of (4·8·10)2(82·10)2. The intermolecular C–H···O hydrogen-bonding interactions link the double-layers to form a 3D supramolecular architecture. Moreover, there are intramolecular and intermolecular π–π interactions in 1 and 2, which stabilize the whole 3D supramolecular architectures. The band gaps of 1 and 2 are 3.19 and 3.09 eV, respectively, indicating the potential of 1 and 2 as semiconductive materials with wide band gaps. Moreover, 1 and 2 emit intense blue-green light, which may be potential photoactive materials.
Graphic Abstract
Two Ag(I)-based 3D supramolecular coordination polymers constructed from a multidentate N-donor ligand and two aromatic polycarboxylate anions via hydrogen-bonding and π–π interactions have been synthesized and characterized. The band gaps and photoluminescent properties of the compounds have been studied.
Annals of Global Analysis and Geometry - In this note we show that, under certain curvature positivity conditions (the weak $${\text {PIC}}-2$$ condition or the nonnegative bisectional curvature... 相似文献
Molecular interactions are crucial in diverse fields of protein folding,material science,nanotechnology,and life origins.Although mounting experimental research controls luminescent behavior by adjusting molecular interactions in light-emitting materials,it remains elusive to correlate microscopic molecular interactions with macroscopic luminescent behavior directly.Here,we synthesized three red luminogens with subtle structural variation and investigated the influence of molecular interactions on their luminescent behavior in solution and aggregate states.Our results indicate that strongπ-πand D-A interactions in both dilute solution(between luminogen and solvent molecules)and aggregate(between luminogens)states cause the redshift in emission,while weak interactions(e.g.,Van der Waals,C–H…π,and C–H…F interactions)enhance the quantum yield.This work provides a thoughtful investigation into the complicated influence of various molecular interactions on luminescent behavior. 相似文献
Journal of Solid State Electrochemistry - Electroless nickel-phosphorus plating is an important surface treatment method for copper due to its good corrosion resistance and nonmagnetic properties.... 相似文献
Designs, Codes and Cryptography - An algorithm substitution attack (ASA) can undermine the security of cryptographic primitives by subverting the original implementation. An ASA succeeds when it... 相似文献
Asymmetric desymmetrization has been demonstrated to be a powerful strategy for building stereocenters in asymmetric synthesis. Herein, a Pd/Cu catalyzed asymmetric desymmetrization reaction with a simple geminal dicarboxylate is reported. A wide scope of imino esters bearing an aryl or heteroaromatic group were compatible with this bimetallic catalytic system. The reactions proceeded smoothly, giving the desired products in good yields with high to excellent regio-, diastereo-, and enantioselectivity (up to 20 : 1 branched:linear, >20 : 1 dr, >99 % ee). Notably, the reaction favored branched selectivity, which is unusual for the Pd-catalyzed allylic alkylation reaction. In addition, the standard product could be easily transformed to other valuable molecules such as chiral allylic alcohols, carbamates, and organic boron compounds. Furthermore, DFT calculations were conducted to explain the origin of the branched selectivity. 相似文献
The recognition of boron compounds is well developed as boronic acids but untapped as organotrifluoroborate anions (R−BF3−). We are exploring the development of these and other designer anions as anion-recognition motifs by considering them as substituted versions of the parent inorganic ion. To this end, we demonstrate strong and reliable binding of organic trifluoroborates, R−BF3−, by cyanostar macrocycles that are size-complementary to the inorganic BF4− progenitors. We find that recognition is modulated by the substituent's sterics and that the affinities are retained using the common K+ salts of R−BF3− anions. 相似文献
International Journal of Theoretical Physics - A semi-quantum bi-signature scheme based on W states is designed, in which two signers sign the same message. The unconditional security of the new... 相似文献