Supramolecular binding motifs are increasingly employed in the design of biomaterials. The ability to rationally design specific yet reversible associations into polymer networks with supramolecular chemistry enables injectable or sprayable hydrogels that can be applied via minimally invasive administration. In this review, we highlight two main areas where supramolecular binding motifs are being used in the design of drug delivery systems: engineering network mechanics and tailoring drug-material affinity. Throughout, we highlight many of the known and emerging chemistries or binding motifs that are useful for the design of supramolecular hydrogels for drug delivery applications.
The recent development of machine learning (ML) and Deep Learning (DL) increases the opportunities in all the sectors. ML is a significant tool that can be applied across many disciplines, but its direct application to civil engineering problems can be challenging. ML for civil engineering applications that are simulated in the lab often fail in real-world tests. This is usually attributed to a data mismatch between the data used to train and test the ML model and the data it encounters in the real world, a phenomenon known as data shift. However, a physics-based ML model integrates data, partial differential equations (PDEs), and mathematical models to solve data shift problems. Physics-based ML models are trained to solve supervised learning tasks while respecting any given laws of physics described by general nonlinear equations. Physics-based ML, which takes center stage across many science disciplines, plays an important role in fluid dynamics, quantum mechanics, computational resources, and data storage. This paper reviews the history of physics-based ML and its application in civil engineering.
The application of hollow glass microsphere/epoxy resin (HGMs/ER) composites is critical for deep-sea submersibles. This study proposes a progressive damage theory for HGMs/ER composites under hydrostatic pressure, based on elastic strain energy derived from self-consistent theory. We determined the ultimate strain energy limit of the HGMs and established their strain energy density distribution and probability distribution functions. The model predicted a chain fracture threshold pressure of 128.0 MPa for the composite material (density: 0.68 g/cm³). Below this threshold, water absorption remained low (e.g., 0.63% at 115 MPa), whereas above it, the water absorption rate increased exponentially with pressure, reaching 1.67% at 165 MPa. This sharp increase was quantitatively linked via an established absorption model to the volume fraction of fractured HGMs. Theoretical predictions of water absorption rates showed excellent agreement with experimental data, providing rigorous validation of the proposed progressive damage theory. These findings provide quantitative failure-prediction criteria and optimization guidelines for deep-sea buoyancy materials.
Mechanics of engineering. Applied mechanics, Technology
This paper outlines the conceptual and numerical design process of a comminution equipment centered on particle breakdown through impact. The process is divided into four stages, starting with the generation of device concepts achieved by developing a needs matrix for an optimal machine. Subsequently, in the second stage, various equipment shape proposals were introduced and tested, with the selection of an optimal proposal determined through performance comparisons. For comparison purposes, simulations utilizing the discrete element method (DEM) were conducted, considering analyses of accumulated power from collisions and particle breakage. Once the optimized prototype was identified, a breakage simulation was conducted to measure the device's reduction ratio. In the third stage, the machine elements of the device were calculated. Finally, in the fourth stage, a series of simulations utilizing the finite element method (FEM) were carried out to perform structural and modal analyses of the final design. The evaluated variables identified in the simulations played a crucial role in optimizing the design, ultimately resulting in a device with a reduction ratio of 1:19.8 for limestone.
Abstract On-chip whispering-gallery-mode cavities enable versatile bosonic wave manipulation but typically rely on near-field evanescent coupling. Here we experimentally demonstrate broadband far-field phonon coupling in a valley metamaterial cavity integrated with a Dirac-cone waveguide—termed a “Dirac strip”. The far-field coupling is confirmed by transmission spectroscopy and spatiotemporal field mapping over distances up to approximately five wavelengths, enabling multiplexed, distance-robust coupling pathways that overcome near-field limitations. By combining near-field and far-field cavities on the same substrate, we achieve amplification and control of non-Hermitian dynamics through loss and distance modulation of sympathetic resonances, directly resolved via piezo-laser interferometry. This work establishes a scalable phononic platform for far-field coupling and paves the way for parallel topological wave processors.
In this study, the influence of the torsional rigidity of the connected shafts, couplings and the working body of the machine, as well as the damping capacity of the coupling, on the torsional impact moment generated in the machine transmission is investigated. Unlike existing classical calculation models, the torsional stiffness of the connected shafts, the torsional damping ability of the coupling and the effects of the moment ratio are taken into consideration together. Under these conditions an analytical expression for the shock moment or resonance coefficient is obtained. The main novelties in obtaining of this expression are the ratio of the torsional stiffness of the connected shafts with the torsional stiffness of the coupling and the acceptance of the moment of resistance of the working body of the machine depending on the torsional stiffness. It has been found that the considered factors have a significant effect on the resonance zone. Finally, different and overlapping conditions are determined when determining the value of the resonance coefficient characterizing the torque impact moment, calculated according to the classical and proposed models.
Vincenzo Sapienza, Marco Miceli, Oleh Petruk
et al.
The maximum energy of electrons in supernova remnant (SNR) shocks is typically limited by radiative losses, where the synchrotron cooling time equals the acceleration time. The low speed of shocks in a dense medium increases the acceleration time, leading to lower maximum electron energies and fainter X-ray emissions. However, in Kepler’s SNR, an enhanced electron acceleration, which proceeds close to the Bohm limit, occurs in the north of its shell, where the shock is slowed by a dense circumstellar medium (CSM). To investigate whether this scenario still holds at smaller scales, we analyzed the temporal evolution of the X-ray synchrotron flux in filamentary structures using the two deepest Chandra/ACIS X-ray observations, performed in 2006 and 2014. We examined spectra from different filaments, measured their proper motion, and calculated the acceleration to synchrotron timescale ratios. The interaction with the turbulent and dense northern CSM induces competing effects on electron acceleration: on one hand, turbulence reduces the electron mean free path enhancing the acceleration efficiency, and on the other hand, lower shock velocities increase the acceleration timescale. In most filaments, these effects compensate each other, but in one region, the acceleration timescale exceeds the synchrotron timescale, resulting in a significant decrease in nonthermal X-ray emission from 2006 to 2014, indicating fading synchrotron emission. Our findings provide a coherent understanding of the different regimes of electron acceleration observed in Kepler’s SNR through various diagnostics.
Heiko Topol, Murtadha J. Al-Chlaihawi, Hasan Demirkoparan
et al.
We analyze bifurcation for a cylindrical membrane capable of swelling subjected to combined axial loading and internal pressure. The material is conceptualized as an isotropic and absorbent matrix (it can swell when it is exposed to some swelling agent, for instance) containing nonabsorbing fibers. More in particular, fibers are symmetrically arranged in two helically distributed families which are (also) mechanically equivalent. Arterial wall tissue has been modeled using this theoretical framework. The matrix of the membrane is taken to be a swellable neo-Hookean material. The swollen membrane is then inflated and axially stretched so that the circular cylindrical geometry is initially preserved. Nevertheless, prismatic, bulging, and bending (composite) bifurcation conditions are analyzed. It is shown that for membranes with and without fibers, prismatic bifurcation does not play a major role. On the other hand, bending and bulging are feasible for fiber-reinforced membranes. Results capture the onset of bifurcation configurations corresponding to bending and bulging and highlight possible coupling during postbifurcation as it might occur, for example, in the formation and development of an abdominal aortic aneurysm.
Material Mechanics is an important course for science and engineering students in higher vocational colleges. However, its unfavorable teaching quality has been a problem for a long time. One of the key factors affecting the teaching effect is the students’ lack of interest in learning. In order to solve this problem, this paper analyzes the common problems in the teaching of Material Mechanics and applies simulation technology to classroom teaching. The results revealed that with the application of simulation technology, abstract concepts can be displayed visually and vividly, thus making it easier for students to understand. In addition, Mises stress nephograms and animations significantly improve students’ learning interest. The teaching method expounded in this paper should be applied to more courses in vocational education.
Introducing a crack in an elastic plate is challenging from the mathematical point of view and relevant within an engineering context of evaluating strength and reliability of structures. Accordingly, a multitude of associated works is available to date, emanating from both applied mathematics and mechanics communities. Although considering the same problem, the given complex potentials prove to be different, revealing various inconsistencies in terms of resulting stresses and displacements. Essential information on crack near-tip fields and crack opening displacements is nonetheless available, while intuitive adaption is required to obtain the full-field solutions. Investigating the cause of prevailing deficiencies inevitably leads to a critical review of classical works by Muskhelishvili or Westergaard. Complex potentials of the mixed-mode loaded Griffith crack, sparing restrictive assumptions or limitations of validity, are finally provided, allowing for rigorous mathematical treatment. The entity of stresses and displacements in the whole plate is finally illustrated and the distributions in the crack plane are given explicitly.
This paper describes the implementation and the results of an online project-based learning (PBL) pedagogy in an advanced fluid mechanics course in a mechanical engineering technology program. This work is a close collaboration between engineering and education faculty and the engineering librarian, and aligns with the new research areas identified by the National Engineering Education Research Colloquies and the ABET Criteria for Accrediting Engineering Technology Programs Criterion 3 (student outcomes, SLO 1 to 5) and Criterion 5 (curriculum, discipline specific content C, D and E). Students were required to work in teams to design and dimension a heating, ventilation, and air-conditioning (HVAC) duct system, a real-world expression of engineering thinking. Students applied information literacy skills to identify relevant engineering codes and standards, such as ASHRAE, and used previously learned content knowledge from various courses to finalize the project. The PBL exercise was chosen as a culminating experience and in support of engineering competencies development. The results showed improvements in the flow of air in ducts content knowledge, professional communication skills, and the ability to collaborate as part of a team, including improving one's ability to work with other students on assignments, listening to the ideas of others, learning from the ideas of others, and evaluating the ideas of others. The students unanimously agreed that the project improved their heating, ventilation, and air-conditioning (HVAC) knowledge beyond the classroom as well as their information seeking skills. Based on the students end of semester course evaluation, this PBL exercise improved their readiness for the workforce.
Material Mechanics is an important subject for science and engineering students in vocational colleges. However, its teaching effect has not been up to par for a long time. In order to improve the teaching quality, this paper discusses four problems existing in the teaching of Material Mechanics and proposes corresponding countermeasures. Rich animations and Mises stress nephograms can be formed using new techniques, such as finite element simulation, making it easier for students to understand abstract concepts. The introduction of engineering-related cases can enhance students’ interest, and students’ hands-on skills and innovation can be improved with open mechanics laboratory. The suggestions are worthy of reference and should be flexibly applied to the teaching of Material Mechanics.
The mechanics of distal femur fracture fixation has been widely studied in bench tests that employ a variety of approaches for holding and constraining femurs to apply loads. No standard test methods have been adopted for these tests and the impact of test setup on inferred construct mechanics has not been reported. Accordingly, the purpose of this study was to use finite element models to compare the mechanical performance of a supracondylar osteotomy with lateral plating under conditions that replicate several common bench test methods. A literature review was used to define a parameterized virtual model of a plated distal femur osteotomy in axial compression loading with four boundary condition sets ranging from minimally to highly constrained. Axial stiffness, longitudinal motion, and shear motion at the fracture line were recorded for a range of applied loads and bridge spans. The results showed that construct mechanical performance was highly sensitive to boundary conditions imposed by the mechanical test fixtures. Increasing the degrees of constraint, for example by potting and rigidly clamping one or more ends of the specimen, caused up to a 25x increase in axial stiffness of the construct. Shear motion and longitudinal motion at the fracture line, which is an important driver of interfragmentary strain, was also largely influenced by the constraint test setup. These results suggest that caution should be used when comparing reported results between bench tests that use different fixtures and that standardization of testing methods is needed in this field.
In the recent outbreak of Covid-19 pandemic, various methods has been adopted to prevent and control the wide spread of pandemic. One of the commonly used method is by detecting the body temperature. This is to isolate those obtained higher body temperature who are possibly infected with the virus. Body temperature detection device is commonly deployed at the entrance of merchants for this purpose. However if one person is detected in one merchant with higher body temperature, this information is not bundled with his/her identity information. Therefore his/her entranced to other merchants are not linked and warned, and causing a possible spread of pandemic ifother customers who appeared in the same premises arenot beingnotified. Inthis work, an IoT based body temperaturedetection system is developed. In this system, the body temperature data is obtained and sent to the internet cloud together with the identity information of that person. This allow easy tracking of the potentialvirus infected person.The collected data can befurther analysed using online analysis tool. Furthermore, the identityinformation is obtained using QR code which eliminate the ordinary procedure of writing personal data into logbook. The QR code method is contactless and able to avoid the infection of virus through the contact of pen and logbook. This system is developed with low-cost material and is affordable for small merchants.
Mechanics of engineering. Applied mechanics, Technology
To design foundations, embankments and other soil structures, geotechnical engineers require methods of assessing engineering properties of soils. Some of the more complex phenomena that occur in soils have often been difficult to recreate in a laboratory: seismic activity, vibration, unsaturated condition, control of principal stresses etc. are areas which have proven difficult to replicate, despite their importance of being understood. This was partly due to the lack of test systems capable of reproducing these effects and the complexity of test systems that were developed to carry out such work. A number of advanced computer/ software controlled systems allow the geotechnical engineer to perform the most complex test regimes via a user-friendly software interface. However, it is difficult to determine firstly parameters needed, e.g. shear speed in soil triaxial testing. In this paper we represent a new approach to determine this shear speed by solving the inverse problem using testing results obtained by the forward procedure. Direct search method, i.e. Adaptive Neuro-Fuzzy Inference System (ANFIS), is developed and applied to soil triaxial shear tests. It allows us to use the advanced sensor and actuator technologies in order to change the traditional triaxial shear apparatus from a mechanical system to a mechatronics system in next work.
Computer engineering. Computer hardware, Mechanics of engineering. Applied mechanics