The suppression of friction between sliding objects, modulated or enhanced by mechanical vibrations, is well established. However, the precise conditions of occurrence of these phenomena are not well understood. Here we address these questions focusing on a simple spring-block model, which is relevant to investigate friction both at the atomistic as well as the macroscopic scale. This allows us to investigate the influence on friction of the properties of the external drive, of the geometry of the surfaces over which the block moves, and of the confining force. Via numerical simulations and a theoretical study of the equations of motion, we identify the conditions under which friction is suppressed and/or recovered, and we evidence the critical role played by surface modulations and by the properties of the confining force.
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http://dx.doi.org/10.1103/PhysRevE.86.016110 | DOI Listing |
Macromol Rapid Commun
January 2025
Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, 610213, P. R. China.
The self-assembly of macromolecular segments promotes the fabrication of polymer microspheres with multiple morphologies. Inspired by the xanthium shells, A dual-driven self-assembly method have defined that enables the construction of multi-dimensional morphologies on the microsphere surface at emulsion-confined interfaces. The two driving forces are derived from the phase separation caused by the immiscibility of macromolecular segments and the different interactions between chain segments of different hydrophilicity and water molecules.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States.
Dimension-engineered synthesis of atomically thin II-VI nanoplatelets (NPLs) remains an open challenge. While CdSe NPLs have been made with confinement ranging from 2 to 11 monolayers (ML), CdTe NPLs have been significantly more challenging to synthesize and separate. Here we provide detailed mechanistic insight into the layer-by-layer growth kinetics of the CdTe NPLs.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
School of Mechanical & Vehicle Engineering, Linyi University, Linyi, Shandong 276000, China.
Molecular dynamics simulations demonstrate that regular conical helices of poly(-phenylene) (PPP) chains can be constructed inside the confined space of single-walled carbon nanocones (CNCs). The translocation displacement of the PPP chain combined with the change of the system total potential energy including each energy component and structural parameters of the formed conical helix is discussed to deeply explore the microstructure evolution, driving forces and dynamic mechanisms. In addition, the influence of chain length, cone angle, temperature, chain number, linked position of benzene rings and the form of Lennard-Jones potential on the helical encapsulation is further studied.
View Article and Find Full Text PDFTalanta
January 2025
Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences & Chongqing School, University of Chinese Academy of Science, Chongqing, 400714, PR China. Electronic address:
Polymers and dendrimers are macromolecules, possessing unique and intriguing characteristics, that are widely applied in self-assembled functional materials, green catalysis, drug delivery and sensing devices. Traditional approaches for the structural characterization of polymers and dendrimers involve DLS, GPC, NMR, IR and TG, which provide their physiochemical features and ensemble information, whereas their unimolecular conformation and dispersion also are key features allowing to understand their transporting profile in confined ionic nanochannels. This work demonstrates the nanopore approach for the determination of charged homopolymers, neutral block copolymer and dendrimers under distinct bias potentials and pH conditions.
View Article and Find Full Text PDFArch Gynecol Obstet
January 2025
Department of Obstetrics and Gynecology, Ulsan University Hospital, University of Ulsan, College of Medicine, 25 Daehakbyeongwon-ro, Dong-gu, Ulsan, 44033, South Korea.
Background: The primary treatment for cervical insufficiency is cervical cerclage (mechanical support) with vaginal progesterone (biochemical support). Cerclage is a surgical procedure that mechanically increases the tensile capacity of the cervix. Therefore, it is necessary to analyse the effects of cerclage from a mechanical point of view.
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