Flexible Ones Research Articles

A new mechanical engineering strategy based on microsphere probe and its application in transition metal dichalcogenides

Mechanical engineering of 2D materials allows continuous and reversible modulation of their electronic and photonic properties. Although photoluminescence (PL) measurement is an effective way to monitor the effects of mechanical forces on 2D semiconductors, there is currently a lack of techniques to enhance PL signals during stress application. This study presents an innovative mechanical engineering approach that integrates a dielectric microsphere as an atomic force microscopy (AFM) probe into a Raman-AFM system. Force–distance curve tests and COMSOL simulations were performed to analyze and estimate the compressive stress exerted by the microsphere. Importantly, the PL signals of transition metal dichalcogenides subjected to microsphere probe's force were enhanced and reveal distinct mechanical responses depending on the substrate rigidity: compressive pressures for rigid substrates and tensile strains for flexible ones. Notably, this strategy not only amplifies spectral signals in real time but also achieves fine stress modulation in the precise targeted material region, demonstrating its superiority in sensitive mechanical engineering applications. Our work offers a new avenue for the deliberate design of mechanical strains in 2D materials, which is crucial for optimizing the performance of related devices.

Ultrathin Flexible Silica Nanosheets with Surface Chemistry-Modulated Affinity to Mammalian Cells.

Flexibility of nanomaterials is challenging but worthy to tune for biomedical applications. Biocompatible silica nanomaterials are under extensive exploration but are rarely observed to exhibit flexibility despite the polymeric nature. Herein, a facile one-step route is reported to ultrathin flexible silica nanosheets (NSs), whose low thickness and high diameter-to-thickness ratio enables folding. Thickness and diameter can be readily tuned to enable controlled flexibility. Mechanism study reveals that beyond the commonly used surfactant, the "uncommon" one bearing two hydrophobic tails play a guiding role in producing sheeted/layered/shelled structures, while addition of ethanol appropriately relieved the strong interfacial tension of the assembled surfactants, which will otherwise produce large curled sheeted structures. With these ultrathin NSs, it is further shown that the cellular preference for particle shape and rigidity is highly dependent on surface chemistry of nanoparticles: under high particle-cell affinity, NSs, and especially the flexible ones will be preferred by mammalian cells for internalization or attachment, while this preference is basically invalid when the affinity is low. Therefore, properties of the ultrathin silica NSs can be effectively expanded and empowered by surface chemistry to realize improved bio-sensing or drug delivery.

67‐3: Development of the Novel Wearable AMOLED Display

The 1.43” hybrid wearable AMOLED display (HWAD) had been developed based on low‐temperature polycrystalline silicon (LTPS) and thin‐film encapsulation (TFE) techniques, which was integrated touch and display functionalities with one driver IC. The 1.43” HWAD border was similar to flexible products, but less than rigid ones above 20%. Meanwhile, the ultra‐thin stack‐up module thickness was also close to that of flexible ones, but reduced about 31.4% compared to traditional rigid display. HWAD utilized a new pixel compensation circuit and a novel compensation algorithm, eventually achieved a flicker indicator FMA value of <3% in 5Hz AOD mode. The logic power consumption of the smart watch in 5Hz AOD model is reduced about 35% compared with the one in 30Hz. The novel HWAD aggregated the advantages of flexible and rigid displays with low process costs. The novel high‐performance HWAD had significant market application prospect.

Intelligent design of reconfigurable flexible assembly fixture for aircraft panels based on smart composite jig model and knowledge graph

The current demand for aircraft panel assembly fixtures necessitates agile manufacturing solutions. Traditional welding fixtures struggle to meet diverse panel types, high quantities, and short manufacturing cycles. Conversely, reconfigurable flexible assembly fixtures offer universality, efficiency and ease of maintenance but heavily rely on designers' experience, hindering knowledge reuse. Existing research on computer-aided fixture design (CAFD) primarily addresses specialized fixtures, neglecting reconfigurable flexible ones, lacking fixture design knowledge systems. Aiming at the above problems, the study proposes an intelligent design method for the reconfigurable flexible assembly fixture for aircraft panels based on the smart composite jig model (SCJM) and knowledge graph (KG). Firstly, based on the SCJM of the aircraft panel type assembly fixture (PSCJM), a configuration design method is proposed to carry out the multi-level design of reconfigurable assembly fixture to instantiate PSCJM containing fixture configuration rules and a module library based on model definition (MBD). Then, a knowledge retrieval method is proposed to search the suitable fixture design knowledge based on KG, assisting designers in achieving the flexible design of aircraft panel reconfigurable assembly fixtures. Finally, practical engineering design validation confirms the method's feasibility and effectiveness in obtaining the reconfigurable flexible assembly fixture design scheme for aircraft panels.

Preparation of novel silica-clay mineral aerogel nanocomposites with outstanding thermal insulation performance

Monolithic silica-based aerogels, produced with tetraethoxysilane (TEOS), reinforced with aramid fibers and incorporating aluminosilicates were prepared for the first time. The nanocomposites were obtained by varying the amount and type of aramid fibers and replacing a part of the synthetic Si (up to 35 wt% of Si) of TEOS by natural aluminosilicates, kaolin and palygorskite. The effects of the type and amount of both fiber and mineral in the materials key properties were investigated. Most samples displayed very low volumetric shrinkages during ambient drying (<5%), high porosity (∼90%), and low bulk densities, down to 120 kg m−3. Composites with both minerals exhibited superinsulating thermal performance, with thermal conductivity reaching values as low as 22 mW m−1 K−1, while also showing excellent thermal stability. The mechanical properties of the designed clay mineral-silica aerogels can be tailored, since the addition of short length fibers (Kevlar pulp) produces stiffer composites, while the longer fibers (Teijinconex) lead to more flexible ones.

Structural Insights into Plant Viruses Revealed by Small-Angle X-ray Scattering and Atomic Force Microscopy.

The structural study of plant viruses is of great importance to reduce the damage caused by these agricultural pathogens and to support their biotechnological applications. Nowadays, X-ray crystallography, NMR spectroscopy and cryo-electron microscopy are well accepted methods to obtain the 3D protein structure with the best resolution. However, for large and complex supramolecular structures such as plant viruses, especially flexible filamentous ones, there are a number of technical limitations to resolving their native structure in solution. In addition, they do not allow us to obtain structural information about dynamics and interactions with physiological partners. For these purposes, small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) are well established. In this review, we have outlined the main principles of these two methods and demonstrated their advantages for structural studies of plant viruses of different shapes with relatively high spatial resolution. In addition, we have demonstrated the ability of AFM to obtain information on the mechanical properties of the virus particles that are inaccessible to other experimental techniques. We believe that these under-appreciated approaches, especially when used in combination, are valuable tools for studying a wide variety of helical plant viruses, many of which cannot be resolved by classical structural methods.

Knowledge, Attitude and Practice Towards Emergency Management of Avulsed Tooth among Dental Practionator in Pakistan: A Questionnaire-Based Survey

Background: The management of dental traumatic injuries, particularly avulsed permanent teeth, necessitates a comprehensive understanding and proficient clinical skills among dental practitioners. With the increasing prevalence of dental injuries due to various factors, the knowledge and practices of dentists in emergency and clinical management are pivotal for successful outcomes. This study aims to evaluate the current state of knowledge, attitudes, and practices among Pakistani dentists regarding the management of avulsed teeth, highlighting areas for improvement and adherence to international guidelines. Objective: To assess the knowledge, attitudes, and practices of dental practitioners in Pakistan concerning the emergency management of avulsed permanent teeth and to identify gaps in knowledge and practice compared to the International Association of Dental Traumatology (IADT) guidelines. Methods: A cross-sectional survey was conducted among 120 dental professionals in Pakistan, using an online questionnaire from August to September 2022. The survey comprised three sections: demographic information, knowledge and attitudes towards dental trauma education, and practices in the emergency management of avulsed teeth. Descriptive statistics were employed to analyze the data, utilizing SPSS version 25.0 for statistical analysis. Results: The survey revealed that 47.5% of respondents felt they received enough information during their undergraduate education, yet a significant proportion reported forgetting much of this knowledge over time. Regarding post-graduation knowledge sources, conferences and medical journals were the most cited (26.7% and 24.2%, respectively). In terms of practice, 79.2% correctly identified HBSS as the optimal storage medium for avulsed teeth, and 60% adhered to rinsing the tooth with saline before replantation. Awareness of the critical extra-oral dry time being under 60 minutes was noted in 59.2% of participants, and a majority were in favor of initiating root canal treatment 7 to 10 days post-replantation for teeth with a closed apex, aligning with IADT recommendations. However, a preference for rigid splints over flexible ones was observed in 54.2% of respondents, indicating a deviation from best practices. Conclusion: The study identified a satisfactory level of knowledge among Pakistani dentists regarding some aspects of avulsed tooth management but also highlighted significant gaps, particularly in the use of flexible splints and recollection of undergraduate training. Continuous education and adherence to IADT guidelines are essential for improving the management of dental traumatic injuries.

Ultra-Tough, highly stable and Self-Adhesive Goatskin-Based intelligent Multi-Functional organogel e-skin as Temperature, Humidity, Strain, and bioelectric four-mode sensors for health monitoring

The rapid development of intelligent electronics has facilitated the transition of electronic devices from rigid systems to flexible ones. Flexible electronic skin (E-skin) that mimics natural biologic skin has attracted widespread attention owing to its significant applications in health management, soft robotics, human–machine interaction, etc. However, the increasing demand for more advanced functionalities imposes higher requirements on E-skin, such as high mechanical strength, flexibility, and biocompatibility. Herein, a top-down strategy was adopted to prepare a multifunctional organogel-based E-skin by using flexible but tough goatskin as the basic framework followed by the filling treatment with a poly(methacrylic acid-acrylamide) (P(MAA-co-AM)) network. This organogel exhibited excellent mechanical strength and puncture resistance, with fracture stress of 3.86 MPa and breaking elongation of 230 %, respectively, thus serving as the second skin layer to protect human body. Unlike conventional water-containing hydrogels, this organogel possessed exceptional biocompatibility and environmental stability, enabling it to operate normally at low temperature (e.g. −20 °C) and after long-term storage (˃ 15 d). More importantly, the crucial properties for practical application, such as adhesion, conductivity, and antibacterial performance, have been integrated into this organogel. A flexible, stretchable, and durable organogel-based sensor was further developed that can accurately monitor large-scale movements and subtle physiological signals of human body within a wide range of temperature and duration. Moreover, it could simultaneously achieve temperature, humidity, strain, and bioelectricity responsiveness on the same platform. This four-mode sensing mechanism can effectively complement and calibrate human body's health data, thus realizing precise monitoring of human health conditions. This work provides a new approach to structural design, enhancement, and multifunctionality of intelligent E-skin, aiming to replicate or even surpass the performance of real animal skin.

Exploring better image captioning with grid features

Nowadays, Artificial Intelligence Generated Content (AIGC) has shown promising prospects in both computer vision and natural language processing communities. Meanwhile, as an essential aspect of AIGC, image to captions has received much more attention. Recent vision-language research is developing from the bulky region visual representations based on object detectors toward more convenient and flexible grid ones. However, this kind of research typically concentrates on image understanding tasks like image classification, with less attention paid to content generation tasks. In this paper, we explore how to capitalize on the expressive features embedded in the grid visual representations for better image captioning. To this end, we present a Transformer-based image captioning model, dubbed FeiM, with two straightforward yet effective designs. We first design the feature queries that consist of a limited set of learnable vectors, which act as the local signals to capture specific visual information from global grid features. Then, taking augmented global grid features and the local feature queries as inputs, we develop a feature interaction module to query relevant visual concepts from grid features, and to enable interaction between the local signal and overall context. Finally, the refined grid visual representations and the linguistic features pass through a Transformer architecture for multi-modal fusion. With the two novel and simple designs, FeiM can fully leverage meaningful visual knowledge to improve image captioning performance. Extensive experiments are performed on the competitive MSCOCO benchmark to confirm the effectiveness of the proposed approach, and the results show that FeiM yields more eminent results than existing advanced captioning models.

Rigidity percolation in a random tensegrity via analytic graph theory.

Functional structures from across the engineered and biological world combine rigid elements such as bones and columns with flexible ones such as cables, fibers, and membranes. These structures are known loosely as tensegrities, since these cable-like elements have the highly nonlinear property of supporting only extensile tension. Marginally rigid systems are of particular interest because the number of structural constraints permits both flexible deformation and the support of external loads. We present a model system in which tensegrity elements are added at random to a regular backbone. This system can be solved analytically via a directed graph theory, revealing a mechanical critical point generalizing that of Maxwell. We show that even the addition of a few cable-like elements fundamentally modifies the nature of this transition point, as well as the later transition to a fully rigid structure. Moreover, the tensegrity network displays a collective avalanche behavior, in which the addition of a single cable leads to the elimination of multiple floppy modes, a phenomenon that becomes dominant at the transition point. These phenomena have implications for systems with nonlinear mechanical constraints, from biopolymer networks to soft robots to jammed packings to origami sheets.

Bid Caps in Noisy Contests

This paper studies optimal bid caps in a multiplayer noisy contest in which a higher bid does not guarantee a sure win. The bid cap can be either rigid or flexible. The former imposes outright bidding restrictions on players’ bids, while the latter taxes bids. A designer structures the bid cap to maximize a weighted sum between aggregate bid and tax revenue. Our analysis characterizes the optimum. A rigid bid is always outperformed by flexible ones, and a laissez-faire policy—i.e., no cap—is optimal when the designer maximizes the aggregate bid. The results also generate novel practical implications. (JEL C72, D44, D82)

A study on the flexible Bricard mechanisms with plane-symmetric structure

The six-bar single-loop overconstrained Bricard linkages have been attracting continuous attention due to their special geometry and remarkable mobility. During the past century, a great number of papers have been published in various aspects, however, almost all of them focus on those only consisting of rigid links and joints. In this paper, the concept of ‘Flexible Bricard Mechanisms’ is introduced to extend these classical overconstrained linkages from the category of rigid-body systems to the scope of flexible ones. In these novel designs, slender elastic beams are used to replace the rigid links and joints, such that the mobility of flexible Bricard mechanisms is achieved not only via the relative motion from rigid joints, but also the large-scale deformations of elastic links. The plane-symmetric case is studied to demonstrate the realization, analysis methodology, and potential applications of this new type of Bricard mechanism. A candidate with a specialized structure is elaborated as a case study, about which a proof-of-concept prototype is developed. Preliminary experiments are conducted to verify the feasibility of the proposed idea.

Single Site Coordination Enabled Construction of Metal-Diketimine-Linked Covalent Organic Frameworks for Boosted Electrooxidation of Biomass Derivative.

Aromatic aldehydes are widely used for the construction of covalent organic frameworks (COFs). However, due to the high flexibility, high steric hindrance, and low reactivity, it remains challenging to synthesize COFs using ketones as building units, especially the highly flexible aliphatic ones. Here, the single nickel site coordination strategy is reported to lock the configurations of the highly flexible diketimine to transform discrete oligomers or amorphous polymers into highly crystalline nickel-diketimine-linked COFs (named as Ni-DKI-COFs). The strategy has been successfully extended to the synthesis of a series of Ni-DKI-COFs by the condensation of three flexible diketones with two tridentate amines. Thanks to the ABC stacking model with high amount and easily accessible single nickel (II) sites on their 1D channels, Ni-DKI-COFs are exploited as well-defined electrocatalyst platforms for efficiently electro-upgrading biomass-derived 5-Hydroxymethylfurfural (HMF) into value-added 2,5-furandicarboxylic acid (FDCA) with a 99.9% yield and a 99.5% faradaic efficiency as well as a high turnover frequency of 0.31s-1 .

Comment on “Rigid production networks” by Pellet and Tahbaz-Salehi

Pellet and Tahbaz-Salehi (2023) studies the aggregate implications of informational frictions in an input-output production network. Firms combine rigid inputs—which must be chosen under incomplete information about the state of the economy—with flexible ones—which can be fully contingent on the state. At the optimum, they choose to rely more heavily on the latter, substituting away from the former. In the aggregate, incomplete information dampens the impact of productivity and demand shocks, and it makes positive demand shocks more inflationary. I discuss the implications of efficiency of equilibrium allocations for Hulten’s theorem and for the welfare effects of more accurate information. Finally, I argue that capital is a rigid input, thus, it is appropriate to calibrate the model using the input-output network for capital. Such a network differs substantially from the intermediate-inputs one.

Comparative study of different Sn wetted W CPSs exposed to NBI fluxes in the OLMAT facility

Four different tin-wetted, tungsten CPS (Capillary Porous System) targets where exposed to NBI pulses in the OLMAT High Heat flux (HHF) facility. They include two flexible ones placed on a TZM support (W meshes and W felt) and two compact ones (sintered W disk and 3D printed W). A comparative study was performed using a fast-frame imaging camera and an infrared pyrometer. Surface temperature increase and homogeneity, particle ejection, CPS damage and overall behaviour were studied for each case. Sn drop/accumulation at the lower part of the targets was observed for all cases when they are heated up to around 400 °C except for the 3D printed W target that has its own Sn deposit. The 3D printed W target presented the best results in all aspects, withstanding heat pulses up to 58 MW/m2 in 100 ms without any damage or particle ejection. On the other hand, the W mesh targets displayed damage at 20 MW/m2 due to a bad thermal contact with the deposit, while the sintered W disk developed a crack during a series of 15 MW/m2 NBI pulses. As might be expected, a reduced increase of temperature during pulses is observed for the two compact W targets. The results and their relevance for the design of a Sn wetted W CPS for application as a DEMO-divertor material are discussed in the present work.

Исследование конструкции земляного полотна на свайном основании с гибким ростверком

Purpose: To investigate the roadbed in the construction of pile foundation united by flexible grillage made of geosynthetic material. To investigate how geosynthetic material will work in such a grillage. To create analytical model of pile foundation with flexible grillage. To determine the strength of such textile material used in the construction. To analyze the advantages and flaws of existing methods for calculating pile foundation structure united by flexible grillage made of geosynthetic material. Methods: Structure parameters of flexible grillage reinforced with geosynthetic material, were calculated using three methodologies: British standard BS 8006-2010, German EBGEO methods, flexible thread calculating method. Results: Arched effect arising in mound body has been studied. Deflections in geosynthetic material were calculated at different loading levels of the structure by soil. Experimental values of forces in geosynthetic material are obtained. "Critical height" is set - the distance from pile top which within, arched effect is formed. Numerical value of uniform emptying has been established which at, pile foundation different rigidity is not revealed on surface. The strength of geosynthetic material of flexible grillage of highway mound foundation is estimated. Existing calculation methods for compliance with experiment results are analyzed. Practical importance: Technical solutions have been developed for two types of flexible grillage structures, both, combined and flexible ones with the use of one or more layers of high-strength geotextile with sand in the form of geo-confining. The developed technical solutions meet all requirements of existing regulatory documents and obtained calculated indicators as well as the requirements for strength, reliability and structure durability. The proposed constructions can be recommended for practical use.

Invariant Percolation Properties in Random Isotropic Systems of Conductive Discorectangles on a Plane: From Disks to Sticks

Nanorod‐ and nanowire‐based films are promising 2D materials for the transparent conductive electrodes, including flexible and stretchable ones. To mimic the shape of elongated conductive nanoparticles and, at the same time, simplify the simulations, different simple geometrical figures are used. During simulation, the shape and the aspect ratio of the particles affect the electrical and optical properties of films. However, some features of the conductive films may be insensitive both to the shape of particles and to their aspect ratio. 2D random systems of isotropically placed, overlapping, identical discorectangles (stadia) with aspect ratios ranging from 1 (disks) to ∞ (zero‐width sticks) are studied. The particular case when only the junction resistance between conductive particles is taken into account is considered. The effect of the aspect ratio and the number density of conductive discorectangles on the behavior of the electrical conductivity, the local conductivity exponent, and the current‐carrying backbone is analyzed. The computer simulations demonstrate that some of the properties of random, isotropic 2D systems of conductive discorectangles are insensitive to the aspect ratios of the particles.

Flexible Acid‐Responsive Polymeric Phosphorescent Microfibers for Tunable Optical Waveguide

AbstractPhosphorescence optical waveguides, flexible ones in particular, are fascinating on account of their fundamental and practical values in photonics and optoelectronics devices. However, the majority of optical waveguides reported so far are fluorescent waveguides, the phosphorescent waveguides, especially ones with both flexibility and stimulus‐response are rarely studied. Herein, one‐dimensional phosphorescent microfibers are developed by employing the flexible polymer as the matrix and the phosphorescent emitter as the transducer for out‐coupled light, and their phosphorescent waveguide attributes are studied in detail. Significantly, benefiting from the non‐covalent clipping of molecular tweezer for Pt(II) triplet emitter, the strong and robust tip emission could be obtained for phosphorescent waveguiding microfiber. Furthermore, the asymmetric propagation of phosphorescent waveguide could be achieved via partly acid treatment, since acid could trigger the guest release accompanied by the emission decline. More interestingly, the phosphorescent microfiber exhibits flexible optical waveguide feature and reversible switching of tip emission. Based on the above, Boolean logic operation is selected to demonstrate the application of tunable tip emission. This study establishes an effective and convenient strategy to realize flexible phosphorescent waveguide with tunable tip emission, which is of fundamental value for designing optical functional elements and manufacturing intelligent flexible photonic devices with promising application potential.

Poly(1,5-diaminoanthraquinone) grafted holey N-doped graphene with superior electrochemical performance via a four-pronged approach

Conductive polymers have attracted intense interest as electrode materials in supercapacitors, especially the flexible ones with graphene-based frameworks. To improve the electrochemical performance, a four-pronged approach was developed here, by efficient fabricating poly(1,5-diaminoanthraquinone) grafted holey N-doped graphene (PDAA-HNrGO) via a solvothermal graft polymerization of 1,5-diaminoanthraquinone (DAA) onto holey N-doped graphene oxide (HNGO) following with reduction. Holey N-doped expandable graphene oxide (HNEGO) was oxidatively cut into smaller HNGO with more functional groups under the solvothermal condition, favoring the graft polymerization. Owing to the unique architecture, the proposed PDAA-HNrGO/rEGO electrodes possessed excellent electrochemical property, especially the cycling stability. The flexible symmetric solid-state supercapacitors (SSSCs) possessed a capacitance of 320 mF cm−2, power density of 275.6 mW cm−2 and energy density of 28.4 mWh cm−2 at 0.50 mA cm−2, with superior capacitance retention of 96% after 10,000 CV cycles.

Enhancing university exam timetabling through the use of a BSet model

Forming university exam schedules in Southern Africa has always been difficult. It is a scheduling problem with strict rules (hard constraints) and flexible ones (soft constraints). Students must take a final exam for most courses they are enrolled in each semester, held in a supervised setting. Therefore, finding a suitable time and location for each student is a common challenge. This paper proposes a solution to this scheduling problem based on the behaviour of bees, using a model called BSet, which uses simulated robotic devices to find and schedule courses. The results show that this approach is efficient and effective in creating exam schedules.