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Metal-organic framework microneedles for precision transdermal drug delivery: design strategy and therapeutic potential.

Metal-organic frameworks (MOFs) are porous materials renowned for their high porosity, large specific surface area, biocompatibility, and biodegradability. Hydrogel microneedles (MNs) is an emerging technology that minimally disrupts the skin or mucosal membranes, bypassing gastrointestinal absorption and the rapid metabolism typical of oral drug delivery. Over the past few decades, both MOFs and MNs have found applications across a range of fields. However, MOFs alone cannot penetrate the skin or mucosal barrier to deliver drugs effectively, and MNs have limited direct loading capacity. When combined, MOFs enhance the loading efficiency of therapeutic agents in hydrogel MNs and optimize their release kinetics. Additionally, the incorporation of MOFs improves the mechanical properties of hydrogel MNs, increasing their permeability to the skin. In turn, hydrogel MNs enable MOFs-whether therapeutically active or drug-loaded-to bypass the skin or mucosal barrier and deliver active compounds directly to the target site for localized treatment. This review discusses the structural features and preparation methods of MOFs and MOF-based MNs, explores their synergistic potential, and highlights strategies for integrating MOFs with MNs to enhance transdermal drug delivery in applications such as wound healing, scar management, acne treatment, and tumor suppression. Finally, we examine the challenges and future potential of MOF-based MNs and offer insights into their role in advancing transdermal therapies.

Aspect-Related Mechanical Properties of the Cortical Bone in the Third Metacarpal Bone of Mares

Complete fractures of the third metacarpal bone (MC III) diaphysis pose a significant clinical challenge, prompting advanced veterinary medicine to utilize constitutive and biomechanical modeling to better understand bone behavior. This study aims to compare the elastic modulus of the MC III cortical bone, supported by measurements of cortical bone thickness and relative density, across the dorsal, lateral, medial, and palmar aspects of the MC III, as well as to evaluate the cortical bone’s response to compressive forces applied in different directions. Given the bone structure can exhibit sex-related differences, MC III bones were isolated from six equine cadaver limbs collected exclusively from mares and imaged using computed tomography (CT) to measure thickness and density. Cortical bone samples were collected from the four aspects of the MC III and subjected to mechanical testing followed by the elastic modulus calculation. Bone thickness and elastic modulus varied across the MC III aspects. Thinner cortical bone on the palmar aspect coincided with a lower sample reaction force-based elastic modulus in the externo-internal direction and a lower axial compression force elastic modulus in the proximo-distal direction. Regardless of the MC III aspect, the cortical bone demonstrated greater resistance to compressive forces when loaded in the vertical plane than in the horizontal plane. The returning of different values in mechanical tests depending on the direction of loading may be attributed to the anisotropic behavior of the cortical bone, which may implicate the increased risk of complete fractures of the MC III diaphysis due to a kick from another horse or a fall, rather than from training or competition-related overload.

Two Conventional Implants versus Four Mini-Dental Implants to Retain Mandibular Overdentures: A Systematic Review of Clinical and Radiological Outcomes.

It is essential to compare conventional dental implants (CDIs) and Mini-Dental Implants (MDIs). This systematic review evaluates the clinical and radiological outcomes of individuals receiving MDI-retained overdentures (ODs) compared to CDI-retained ODs. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed for the current systematic review. The PubMed, Scopus, and Cochrane databases were examined for evidence-based research articles addressing the clinical and radiological outcomes of MDI and CDI published from January 2013 to September 2024. Two independent specialists conducted an autonomous search and established predefined screening criteria. The risk of bias (RoB) for randomized controlled trials (RCTs) was evaluated using the criteria established by the Cochrane Handbook for Systematic Reviews of Interventions for scientific merit. The informational database and manual searches produced 242 papers. Eight RCTs were examined after eliminating duplicates and organizing the publications according to the qualifying criteria. MDI-retained ODs have been shown to provide numerous benefits, including reduced bone resorption, enhanced aesthetics, occlusion, and tooth location, improved occlusal load direction, and maintenance of occlusal vertical dimension. The current systematic review suggests that using mini-dental implants to retain overdenture prostheses could be a viable alternative treatment option due to the high survival rates, acceptable marginal bone loss, and improvements in patient satisfaction and oral health-related quality of life metrics.

The Strain Heterogeneity and Microstructural Shear Bands in AZ31B Magnesium Alloy

In this study, the strain distribution and microstructural evolution of the AZ31B magnesium alloy were analyzed via uniaxial tensile loading combined with an in situ tensile test. The results conclusively showed that the strain on the AZ31B magnesium alloy’s surface is not uniform during tensile loading in a specific direction, and the emergence of localized twins fosters the development of densely intersecting shear bands, whereas prismatic slip intensified the strain concentration within these bands, ultimately bolstering their strength. These densely packed, discrete shear bands exhibited a dual role: they stabilized plastic deformation processes while simultaneously contributing to material failure. By elucidating the intricate relationship between grain orientation, evolution of the microstructure, and mechanical properties, we could effectively mitigate the detrimental orientations and deformations in anisotropic-polycrystalline materials to enhance their plasticity. The research carries paramount scientific significance and is the key to maximizing the engineering application potential of the AZ31B magnesium alloy.

Analysis of Density-Dependent Cell Structure of EPP Bead Foams Under Compression

Abstract Background Closed cell polymer bead foams are widely used in industrial applications due to their extraordinary damping and insulation properties. To understand the structure-property-relations at different deformation states the volumetric structure of polymer walls, cells and beads should be statistically analysed. Objective The presented work is focused on the statistical analysis of the changing cell structure of expanded polypropylene bead foams of different density at distinct compression states. Methods Cylindrical bead foam specimens are scanned by x-ray computed tomography at 3-5 different compression states. The reconstructed volume information is segmented and statistically analysed. Results It could be shown that, among others, the cell sphericity and their orientation relative to the plane normal to the loading direction are sensitive parameters to the deformation state. With regard to the material symmetry level, a shift of the isotropic foam to transversal isotropic structure was observed. No sudden, stability related, deformation or failure could be observed. Conclusions Good metrics for the deformation analysis of expanded polypropylene bead foams from in-situ computed tomography tests are the cell sphericity and orientation. Compression deformation leads to a gradually change of material symmetry level from isotropy to anisotropy.

Numerical simulations of the splitting tensile behaviour of needle-punched carbon/carbon composites

Carbon/carbon (C/C) composites are materials developed for applications requiring excellent mechanical and thermal properties at elevated temperatures. Needle-punching has been used to improve the delamination resistance of C/C composites; however, its effect on tensile behaviour has yet to be fully understood. This work studies the splitting tensile behaviour of needle-punched C/C composites numerically using experimentally validated finite element (FE) simulations with a damage initiation criterion. The splitting tensile test, comprising the diametral loading of flattened Brazilian discs (FBDs), was employed for the simulations and validation. A mesoscale model of the composite FBD specimen was built, in which each composite layer was explicitly modelled, including cohesive interfacial behaviour. The composite needle fibre bundles were modelled using truss elements. The FE simulations showed the crucial role that needled fibre bundles play in the C/C composite tensile performance by carrying tensile stresses perpendicular to the loading direction and reducing the levels of localised deformation in the central region of the specimen at the early stages of loading. Furthermore, the damage initiation criterion showed that when the needle fibre bundles are included in the FE simulation, the extension of damaged areas is less than in the simulations without needled fibre bundles. In addition, the numerical results showed that increasing the number of needled fibre bundles reduced the extension of the damage in the matrix.

Direct Load Control Strategy of Centralized Chiller Plants for Emergency Demand Response: A Field Experiment

As the penetration rate of renewable energy in the power grid increases, the imbalance between power supply and demand has become one of the key issues. Buildings and their heating, ventilation, and air conditioning (HVAC) systems are considered excellent flexible demand response (DR) resources that can reduce peak loads to alleviate operational pressures on the power grid. Centralized chiller plants are regarded as flexible resources with large capacity and rapid adjustability. The direct load control of chiller plants can respond to the power grid within minutes, making them highly suitable for participation in emergency DR. However, existing studies are generally based on simulations and lack experimental research in actual large-scale buildings to demonstrate the effectiveness of this method and provide related lessons learned. This study conducted field experiments on a centralized chiller plant within an industrial building in Guangdong, China. The results indicate that the strategy of shutting down chiller plants is an effective DR measure. It can complete the load reduction process within 15 min, rapidly decreasing the system power by 380~459 kW, with a maximum duration of up to 50 min, without significantly affecting the thermal comfort of indoor occupants. Additionally, the impact of existing control logic on the participation of chiller plants in the DR process is also discussed.

Anisotropic Hardening of HC420 Steel Sheet: Experiments and Analytical Modeling

Choosing the appropriate yield function is essential to precisely predicting the anisotropic hardening behavior of steel metals considering general loading directions. This research investigates the anisotropic hardening behavior of HC420 steel sheet by combining experimental and analytical modeling. Experiments are conducted for uniaxial tensile tests according to the three different directions and bulging tests to obtain hardening data. The experimental findings show that the loading direction affects the anisotropic behavior of HC420 steel’s strength and plastic deformation. The Chen-coupled quadratic and non-quadratic (Chen-CQN) approach is used to ensure the convexity of the HC420 steel. By comparing the Chen-CQN approach with the Yld2000-2d and Stoughton-Yoon’2009 yield functions, the Chen-CQN approach shows superiority in predicting the hardening behavior of the HC420 sheet, exhibiting a more straightforward numerical implementation and enhanced accuracy in yield stress predictions under different loading directions. Results from experimental hardening tests reveal that the Chen-CQN function precisely and flexibly characterizes the yield surface of HC420 steel, with a constant variation of within 2% from its predictions.

Dynamic response characteristics of floating offshore photovoltaic systems with anchor position deviations under extreme environmental conditions

Floating offshore photovoltaic (FOPV) systems are key technologies for harnessing offshore solar resources, playing a crucial role in mitigating global climate change. Anchoring systems, essential components of FOPV systems, ensure operational safety by limiting floating body's displacement. However, factors such as positioning errors, uneven seabed, and inhomogeneous loads make it challenging to install anchors exactly at their designed locations. These deviations can significantly alter the system's dynamic responses, particularly under extreme environmental conditions, posing potential safety risks. This study aims to explore the dynamic response characteristics of FOPV systems with varying anchor position deviations under extreme sea states, offering valuable insights for system design. First, a coupled numerical model is developed to capture interactions between multiple modules and their mooring lines. Then, the effects of anchor offset distance, direction, relative position, and the incident direction of sea loads on modules motion and mooring tension are discussed. The results indicate that anchor deviations along the mooring projection direction significantly affect the maximum horizontal motion, maximum mooring tension, and minimum mooring safety coefficient, while the maximum heave motion remains largely unaffected. Additionally, when the displaced anchor and the direction of environmental loads acting on the FOPV system are on the same side, the system's maximum dynamic responses are significantly higher compared to those due to the displaced anchor on the leeward side.

In-situ experimental investigation of the small fatigue crack behavior in CP-Ti: The influence of loading parameters and directions

This study quantitatively investigates the influence of loading parameters and directions on the behavior of small fatigue cracks (SFC) in commercially pure titanium (CP-Ti). It is observed that reductions in peak stress and increases in stress ratio correlate with a decrease in SFC growth rate and an intensification of growth rate fluctuations. Notably, crack growth along the transverse direction (TD) generally exhibits lower rates compared to that along the rolling direction (RD), with more pronounced fluctuations. Through metallographic analysis of crack paths, roughness-induced crack closure (RICC) is identified as a significant factor contributing to the observed variations in SFC growth behavior under different loading conditions. Furthermore, electron backscatter diffraction (EBSD) characterization reveals that crack propagation along the RD is primarily governed by prismatic slip, while TD samples exhibit more engagement of non-prismatic slip systems with higher activation stress. This results in a more tortuous crack path and pronounced crack arrest phenomena. Finally, a modified multi-scale rate prediction model based on the reference stress ratio method is proposed. Comparative analysis demonstrates that the modified model outperforms existing models by offering enhanced predictive capability across diverse loading conditions, thereby reinforcing its robustness in predicting SFC behavior of CP-Ti.

Influence of Implant Geometry on the Surface Strain Behavior of Peri-Implant Bone: A 3D Analysis.

To ensure long-term implant success, it is crucial to understand the force transmission from the implant to the surrounding bone. In dentistry, bioengineering methods are applied to investigate these processes. The aim of this study was to analyze the influence of different implant geometries on the surface strain behavior of porcine mandibles under load using a 3D optical camera system in combination with digital image correlation. Four different implant types were subjected to a force of 200 N in three different loading directions (axial, non-axial 15°, and non-axial 30°). Under axial loading, parallel-walled implants exhibited lower surface strain values on the peri-implant bone compared with tapered implants. However, when subjected to non-axial loading, these parallel-walled implants showed a substantial relative increase in strain by approximately a factor of 2.96 compared with axial conditions. At a 30° non-axial angle, long, tapered implants with a smaller diameter (BLX 3.75) produced lower peri-implant bone strains than implants with larger diameters and shorter lengths, while short, tapered implants (BLT) demonstrated a lower relative increase in strain (factor ~1.49) from axial to non-axial loading. Under non-axial loading, long, tapered implants with a small diameter resulted in lower strains in the peri-implant bone compared with implants with a larger diameter and shorter length. It was found that non-axial loads lead to higher strains than axial loads. Therefore, the success of implantation could be significantly influenced by selecting an appropriate implant geometry and the correct angulation of the implant.

What about the mechanical behaviour and modelling of arteries in radial direction?

Understanding the physiological behaviour of arteries in the radial direction is crucial for establishing a reference point to detect and analyse pathological changes. In this study, the influence of the radial component of the aorta will be investigated by performing experimental tests on porcine aortic tissue in the three main directions of the aorta: circumferential, longitudinal and radial. The results obtained in all directions will be analysed and compared in order to contribute to a comprehensive understanding of the healthy behaviour of the vessel. Our results demonstrate that the aorta exhibits nonlinear behaviour under compression and tensile loading in the radial direction. Moreover, tissue stiffening progresses more prominently under compression compared to tensile loading. We have found that the tensile stiffness in the ATA is higher compared to the other two regions examined. The Neo-Hookean and Demiray models were selected to describe the isotropic contribution when fitting the uniaxial response of the circumferential and longitudinal samples using the GOH model. Neo-Hookean model fall short (R2=0.235) in accurately replicating the observed behaviour of the aorta in the radial direction and Demiray model showing better fitting results (R2=0.994).

Numerical Investigation Into Mechanical Behavior of Metastable Olivine During Phase Transformation: Implications for Deep‐Focus Earthquakes

AbstractOne hypothesized mechanism that triggers deep‐focus earthquakes in oceanic subducting slabs below ∼300 km depth is transformational faulting due to the olivine‐to‐spinel phase transition. This study uses finite element modeling to investigate phase transformation‐induced stress redistribution and material weakening in olivine. A thermodynamically consistent constitutive model is developed to capture the evolution of phase transformation in olivine under different pressure and temperature conditions. The overall numerical model enables considering multiscale material features, including the polycrystalline structure, mesoscale heterogeneity, and various phases or variants of phases at the microscopic level, and accounts for viscoplastic behaviors with thermo‐mechanical coupling effects. The model is validated with several benchmarks, including a phase diagram of phase transformation from olivine to spinel. The validated model is used to study the interactive behaviors between defects (heterogeneity) and phase transformation. The simulation results reveal that spinel formation under pressure initiates near inclusions and along the grain boundaries, consistent with experimental observations. At lower temperatures, the transformation leads to the formation of thin conjugate bands of spinel diagonal to the compression loading direction. Local stress analysis along these bands also suggests the initiation of faulting. In contrast, the numerical results at higher transformation rates show that significant spinel formation occurs over a larger area at elevated temperatures, leading to ductile behavior, which agrees with experimental findings. Numerical simulation of multiple inclusions under confined pressure also shows the formation of a network of spinel bands resembling phase‐transformation patterns observed in the laboratory experiments. Additionally, stress softening patterns due to phase transformation are similar to experimental observations.

Relationship between UCS and Anisotropic Angle: A Case Study for Slate of Himalaya Region

The strength of rocks exhibits anisotropy, because of its mode of formation and its developing through different pressure and temperature environment. A rock can display anisotropy due to inhomogeneity, where sedimentary varying with the degree of the anisotropic plane. This strength anisotropy" refers to the change in intact rock strength under uniaxial loading conditions based on the orientation of anisotropy, the strength and deformation behavior of rocks under load is critical for underground excavations, mining, and civil engineering projects, as it directly impacts the stability of such structures. This study examines the strength index, which is influenced by the anisotropic plane at different loading angles. The rock material, characterized by layers developed by platy minerals with sometime varying grain sizes, shows that an increase in foliation degree to loading angle directly impacts its strength. In slate, the strength index is influenced by the anisotropic plane and loading direction, which are also controlled by characters of mineral grains. This study seeks to enhance the existing understanding of this behavior by analyzing uniaxial compressive strength (UCS) performed on anisotropic low grade metamorphic rock.

Study of the mechanical compression properties of Rosa sterilis S.D. Shi based on FEM

Understanding the mechanical properties of Rosa sterilis S.D. Shi is important for the design and improvement of related mechanical equipment for planting, picking, processing, and transporting Rosa sterilis S.D. Shi. Compression damage is a common form of mechanical damage in agricultural products, especially during automated mechanical production. Therefore, this study establishes a three-dimensional model of seedless prickly pear fruit based on image processing technology and analyzes the compressive mechanical properties of seedless prickly pear under different directions through experiments combined with finite element method simulation. In both simulation and actual results, the average correlation coefficients were found to be 0.99 and 0.98 for the vertical compression direction and the horizontal compression direction, respectively. The above results show that our finite element compression model can provide a comprehensive understanding of the mechanical properties of Rosa sterilis S.D. Shi fruits under different directional loads. There is significant directional sensitivity in the compression resistance of Rosa sterilis S.D. Shi fruits have horizontal compression resistance greater than vertical compression resistance. The results of this study are of great significance for the development of mechanized automation in the Rosa sterilis S.D. Shi industry and for ensuring the quality of Rosa sterilis S.D. Shi fruits.

An Innovative Approach to Tailor Sandwich Core Structures for Multi-Directional Loading Scenarios

Enhancing the mechanical properties of sandwich core structures is important for crashworthiness applications, including protecting passengers and payloads. Existing structures, such as prismatic cells, present limitations like reduced lateral mechanical properties, among others. Non-prismatic reinforcements (NPRs) are introduced as an alternative to developing core structures tailored for multiple loading scenarios. Several NPR ideas are presented. While additive manufacturing allows for exploring the inner space of core structures with different NPRs, manufacturing such structures may present challenges due to their complexities. One of the NPR ideas was combined with the hexagonal honeycomb, a sandwich core widely used for crashworthiness applications, to create a non-prismatic reinforced honeycomb (NPRH). Utilizing fused filament fabrication, NPRH specimens were manufactured as self-supporting structures at three scales. Quasi-static compression experiments were performed in multiple loading directions. Because comparing structures’ mechanical properties in multiple loading directions simultaneously may present difficulties, the multi-direction comparison factor and the angle comparison factor are presented as alternatives that relate mechanical properties in multiple loading directions and that can be adapted to different loading scenarios. These parameters were used to compare the NPRH with structures from the literature. The NPRH showed greater specific energy absorption, positioning it as a possible solution for multi-loading crashworthiness applications.

Material extrusion of TPU: thermal characterization and effects of infill and extrusion temperature on voids, tensile strength and compressive properties

PurposeThis study aims to investigate the tensile strength and compressive behaviour of two thermoplastic polyurethane (TPU) filaments produced via material extrusion (ME): TPU 95A and Reciflex (recycled).Design/methodology/approachTensile strength and compressive behaviour are assessed. The influence of extrusion temperature and infill pattern on these properties is examined, supported by thermal characterization, surface morphology analyses and a comprehensive comparison with existing literature. An analytical method is presented for estimating the solid ratio of ME parts, using an ellipse model to describe the material bead geometry.FindingsReciflex is generally stiffer than TPU 95A in both tensile and compressive tests. Specimens loaded orthogonally in compression tests exhibited stiffer behaviour than those loaded parallelly, and higher tensile properties were typically observed when material beads were deposited parallel to the load direction. Unlike TPU 95A, Reciflex is sensitive to extrusion temperature variations.Social implicationsBy comparing recycled and virgin TPU filaments, this research addresses waste management concerns and advocates for environmentally sustainable production practices in the broadly used filament/based ME technique.Originality/valueThis study provides an extensive comparison of computed values with existing literature, offering insights into how different materials may behave under similar processing conditions. Given ongoing challenges in controlling melt flow during extrusion, these results may offer insights for optimizing the production of ME parts made with thermoplastic elastomers.

A Review of Diagnostic Methods for Yaw Errors in Horizontal Axis Wind Turbines

Yaw errors occur in wind turbines either during the installation stage or because of the aging of devices. It reduces the wind speed in the rotor axial direction and increases the structural loads in the lateral direction. Diagnosing yaw error rapidly and accurately is crucial for avoiding the introduced under-performance. In this review paper, we first introduce the fundamental concepts and principles of wind turbine yaw control strategies, and we discuss two types of yaw errors (i.e., the static yaw error and the dynamic yaw error) with their corresponding causes. Subsequently, we outline the existing yaw error diagnostic methods, which are based on the LiDAR (light detection and ranging) data, the SCADA (supervisory control and data acquisition) data, or a combination of the two, and we discuss the advantages and disadvantages of various methods. At last, we emphasize that the diagnostic performance can be improved via the combination of the LiDAR data and the SCADA data, and it benefits from an in-depth understanding of the salient features and influential factors associated with the yaw error. Meanwhile, the potential of intelligent clusters and digital twins for detecting yaw errors is discussed.

Horizontal Cyclic Bearing Characteristics of Bucket Foundation in Sand for Offshore Wind Turbines

During the service period, the offshore wind turbine foundation mainly bears the wind load from the upper structure and the periodic loads such as wave load and sea currents from the lower structure. Long-term cyclic loads have an important impact on the cumulative deformation, foundation stiffness changes, and horizontal ultimate bearing capacity of the offshore wind turbine bucket foundation. This paper conducts cyclic loading tests on mono-bucket foundations under unidirectional and multidirectional cyclic loading conditions based on the multidirectional intelligent cyclic loading system of offshore wind turbine foundations and analyzes the cumulative effects of the loading direction, vertical load, and drainage status on the mono-bucket foundation during the cyclic loading process, effects of rotation angle, cyclic stiffness, and monotonic bearing capacity of foundation after cycles. The research results show that multidirectional cyclic loading significantly reduces the cyclic cumulative rotation angle of the mono-bucket foundation, and the maximum reduction rate can reach more than 50%. After unidirectional and multidirectional cyclic loading, the bearing capacity of the bucket foundation can be increased by up to 30% and 20%, respectively. At the same time, this paper proposes calculation formulas for vertical load, number of cyclic loading, and normalized cumulative rotation and establishes a calculation method for vertical load and bearing capacity of the foundation after cycles.

SOFCs integrated with SMES under dynamic power control using Chernobyl disaster optimizer

The current study uses the Chernobyl disaster optimizer (CDO), a new metaheuristic optimizer, to identify the seven unknown parameters of solid oxide fuel cells (SOFCs). The procedures of the CDO is based on physical behavior of the elaborated radiations from the well-known Chernobyl disaster according to their mass, speed, frequency, and degree of ionization. The sum of square errors (SMSE) among the estimated and the real measured output voltage datasets of SOFCs is minimized employing the CDO. Set of boundaries of the SOFC’s process is taken into consideration with the problem formulation. SOFCs stack’s model is examined at 800οC and 900οC and its performance is confirmed. The CDO extracts more precise SOFCs’ parameters compared to other competitors. The CDO’s convergence patterns and the SOFCs unit’s performance are studied and proved at steady-state by comparing its results to a number of recognized algorithms under varied operating scenarios. A significant SMSE’s values of 3.46 µV2 and 7.38 µV2 are attained at 800οC and 900οC, respectively by the CDO. As a result, the polarization principal curves of the measured and estimated voltage datasets are checked and verified with very close matching. The dynamic behavior of the SOFCs stack is examined in relation to direct load, electric networks, and superconducting magnetic energy storage devices (SMES) for additional validation and illustration. The role of the SOFCs stack in controlling the active and reactive power delivered to the network and direct load is investigated using two controllers: one to control the inverter, which converts the SOFC’s dc output to the main network, and the other to control the SMES. The Simulink/MATLAB environment is used to indicate the validity of the proposed framework under both steady-state and dynamical conditions. The comprehensive assessments show that the CDO capabilities are very effective when used with microgrids.