Audible squeaking has put the reputation of ceramic bearings for total hip replacements into question. Inter-articular friction induces vibrations in the ceramic head which are transferred through the head-taper interface to the femoral stem. If excited to sufficient amplitudes, squeaking can be emitted by the stem. Hence, the damping and amplification properties of this interface have a crucial influence on stem vibrations. The aim of this study was to determine the vibration transfer behavior between the head and the taper of a femoral stem and its dependence on the assembly force, in order to assess its influence on the development of audible squeaking. A ceramic head was assembled on a titanium femoral stem taper with high and low forces. Frequency response functions characterizing the head-stem interface were determined experimentally. The interface demonstrated negligible influence on vibration transfer in the squeaking frequency range (1-5 kHz). However its damping effect in lower and higher frequency ranges was significant and some areas of amplification were also found. Although squeaking vibration was not influenced by the particular interface studied, the method established can be utilized to trace taper designs with dynamic properties that decrease the susceptibility to squeaking.
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http://dx.doi.org/10.1016/j.medengphy.2013.04.001 | DOI Listing |
Nat Commun
January 2025
Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic University, Shenzhen, 518055, People's Republic of China.
Crystalline pentacene is a model solid-state light-harvesting material because its quantum efficiencies exceed 100% via ultrafast singlet fission. The singlet fission mechanism in pentacene crystals is disputed due to insufficient electronic information in time-resolved experiments and intractable quantum mechanical calculations for simulating realistic crystal dynamics. Here we combine a multiscale multiconfigurational approach and machine learning photodynamics to understand competing singlet fission mechanisms in crystalline pentacene.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States.
Understanding charge transport in semiconductor quantum dot (QD) assemblies is important for developing the next generation of solar cells and light-harvesting devices based on QD technology. One of the key factors that governs the transport in such systems is related to the hybridization between the QDs. Recent experiments have successfully synthesized QD molecules, arrays, and assemblies by directly fusing the QDs, with enhanced hybridization leading to high carrier mobilities and coherent band-like electronic transport.
View Article and Find Full Text PDFJ Acoust Soc Am
January 2025
Urban Construction Center of Lucheng District of Wenzhou, Wenzhou, 325000, China.
The identification of vibration and reconstruction of sound fields of plate structures are important for understanding the vibroacoustic characteristics of complex structures. This paper presents a data-physics driven (DPD) model integrated with transfer learning (DPDT) for high-precision identification and reconstruction of vibration and noise radiation of plate structures. The model combines the Kirchhoff-Helmholtz integral equation with convolutional neural networks, leveraging physical information to reduce the need for extensive data.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
Time-resolved spectroscopy is an important tool for probing photochemically induced nonequilibrium dynamics and energy transfer. Herein, a method is developed for the ab initio simulation of vibronic spectra and dynamical processes. This framework utilizes the recently developed nuclear-electronic orbital time-dependent configuration interaction (NEO-TDCI) approach, which treats all electrons and specified nuclei quantum mechanically on the same footing.
View Article and Find Full Text PDFSci Rep
January 2025
Laboratory of Materials, Nanotechnologies and Environment, Center of Sciences of Materials, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP:1014, 10000, Rabat, Morocco.
In this study, novel polyaniline-coated perovskite nanocomposites (PANI@CoTiO and PANI@NiTiO) were synthesized using an in situ oxidative polymerization method and evaluated for the photocatalytic degradation of Rhodamine B (RhB) a persistent organic pollutant. The nanocomposites displayed significantly enhanced photocatalytic efficiency compared to pure perovskites. The 1%wt PANI@NiTiO achieved an impressive 94% degradation of RhB under visible light after 180 min, while 1wt.
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