Influence of Air Plasma Pretreatments on Mechanical Properties in Metal-Reinforced Laminated Wood

The use of wood-based materials in building and construction is constantly increasing as environmental aspects and sustainability gain importance. For structural applications, however, there are many examples where hybrid material systems are needed to fulfil the specific mechanical requirements of the individual application. In particular, metal reinforcements are a common solution to enhance the mechanical properties of a wooden structural element. Metal-reinforced wood components further help to reduce cross-sectional sizes of load-bearing structures, improve the attachment of masonry or other materials, enhance the seismic safety and tremor dissipation capacity, as well as the durability of the structural elements in highly humid environments and under high permanent mechanical load. A critical factor to achieve these benefits, however, is the mechanical joint between the different material classes, namely the wood and metal parts. Currently, this joint is formed using epoxy or polyurethane (PU) adhesives, the former yielding highest mechanical strengths, whereas the latter presents a compromise between mechanical and economical constraints. Regarding sustainability and economic viability, the utilization of different adhesive systems would be preferable, whereas mechanical stabilities yielded for metal-wood joints do not permit for the use of other common adhesive systems in such structural applications. This study extends previous research on the use of non-thermal air plasma pretreatments for the formation of wood-metal joints. The plasma treatments of Norway spruce [Picea abies (L.) Karst.] wood and anodized (E6/EV1) aluminum AlMgSi0.5 (6060) F22 were optimized, using water contact angle measurements to determine the effect and homogeneity of plasma treatments. The adhesive bond strengths of plasma-pretreated and untreated specimens were tested with commercial 2-component epoxy, PU, melamine-urea formaldehyde (MUF), polyvinyl acetate (PVAc), and construction adhesive glue systems. The influence of plasma treatments on the mechanical performance of the compounds was evaluated for one selected glue system via bending strength tests. The impact of the hybrid interface between metal and wood was isolated for the tests by using five-layer laminates from three wood lamellae enclosing two aluminum plates, thereby excluding the influence of congeneric wood-wood bonds. The effect of the plasma treatments is discussed based on the chemical and physical modifications of the substrates and the respective interaction mechanisms with the glue systems.

Biomechanical Characteristics of the Knee Joint during Gait in Obese versus Normal Subjects

Knee osteoarthritis (OA) is a growing source of pain and disability. Obesity is the most important avoidable risk factor underlying knee OA. The processes by which obesity impacts osteoarthritis are of tremendous interest to osteoarthritis researchers and physicians, where the joint mechanical load is one of the pathways generally thought to cause or intensify the disease process. In the current work, we developed a hybrid framework that simultaneously incorporates a detailed finite element model of the knee joint within a musculoskeletal model to compute lower extremity muscle forces and knee joint stresses in normal-weight (N) and obese (OB) subjects during the stance phase gait. This model accounts for the synergy between the active musculature and passive structures. In comparing OB subjects and normal ones, forces significantly increased in all muscle groups at most instances of stance. Mainly, much higher activation was computed with lateral hamstrings and medial gastrocnemius. Cartilage contact average pressure was mostly supported by the medial plateau and increased by 22%, with a larger portion of the load transmitted via menisci. This medial compartment experienced larger relative movement and cartilage stresses in the normal subjects and continued to do so with a higher level in the obese subjects. Finally, the developed bioengineering frame and the examined parameters during this investigation might be useful clinically in evaluating the initiation and propagation of knee OA.

TRF2 rescues pathogenic phenotypes in Duchenne muscular dystrophy cardiomyocytes derived from human iPSCs

Duchenne muscular dystrophy (DMD) is a severe muscle wasting disease caused by the lack of dystrophin. Heart failure, driven by cardiomyocyte death, fibrosis, and the development of dilated cardiomyopathy, is the leading cause of death in DMD patients. Current treatments decrease the mechanical load on the heart; however, these treatments do not address the root cause of dilated cardiomyopathy: cardiomyocyte death. Previously, we showed that longer telomeres are protective against dilated cardiomyopathy. Here we investigated the role of telomeres as a target for therapy in DMD cardiomyocytes using human induced pluripotent stem cells (iPSCs) to model the disease. Compared to healthy controls, DMD cardiomyocytes exhibited reduced telomere lengths, cell size, nuclear size, and sarcomere density. The telomere-binding protein, TRF2, is a core component of the shelterin complex, which protects chromosome ends. TRF2 levels are reduced relative to healthy controls in DMD cardiomyocytes. We hypothesized that decreased TRF2 drives telomere attrition and subsequent cardiomyocyte death in the progression of dilated cardiomyopathy. Our data show that TRF2 overexpression prevented telomere attrition and also rescued deficits in cell size, nuclear size, sarcomere density, and calcium handling. These data highlight the benefits of TRF2 upregulation as a potential gene therapy to delay the onset of dilated cardiomyopathy.

Operating Characteristic Analysis and Verification of Short-Stroke Linear Oscillating Actuators Considering Mechanical Load

Linear oscillating machines are electric devices that reciprocate at a specific frequency and at a specific stroke. Because of their linear motion, they are used in special applications, such as refrigerators for home appliances and medical devices. In this paper, the structure and electromagnetic characteristics of these linear oscillating machines are investigated, and the stroke is calculated according to voltage and motion equations. In addition, static and transient behavior analysis is performed, considering mechanical systems such as springs, damping systems, and mover mass. Furthermore, in this study, the magnetic force is analyzed, experiments are conducted according to the input power, and the current magnitude and stroke characteristics are analyzed according to the input frequency. Finally, the study confirmed that the most efficient operation is possible when the electrical resonance frequency matches the resonance frequency of the linear oscillating machines.

Influence of Miller cycle on thermal load of high-boosted diesel engine

With the increase of the engine intensified degree, mechanical load and thermal load become to the two main factors limiting the engine to intensify. Application of Miller cycle, which can be realized by late intake valve closing (LIVC) and deeper late intake valve closing (DLIVC), has the potential to reduce the effective CR, mechanical load, and thermal load. In this paper, the effects of LIVC and DLIVC on the mechanical load and thermal load of a boosted DI diesel are experimentally compared. Compared to the original base case, the average cylinder temperature of LIVC and DLIVC is reduced by 90 and 52 K. The exhaust temperature of LIVC and DLIVC decreased by 26 and 14 K, and the maximum combustion pressure of LIVC and DLIVC decreased by 1.6 and 9.7 bar. The pumping losses of LIVC and DLIVC are reduced by more than 25%, while the actual cycle power does not decrease due to the late closing of the inlet valve. The fuel consumption rate decreased from 250.1 g/kWh of base case to 240 g/kWh of LIVC, reduced by 4.0%. The indicated thermal efficiency increased from 41.9% of base case to 43.7% and 42.5% of LIVC and DLIVC. Miller loss is only 2.55% with Miller inlet phase.

An Overview of the Role of Mechanical Stretching in the Progression of Lung Cancer

Cells and tissues in the human body are subjected to mechanical forces of varying degrees, such as tension or pressure. During tumorigenesis, physical factors, especially mechanical factors, are involved in tumor development. As lung tissue is influenced by movements associated with breathing, it is constantly subjected to cyclical stretching and retraction; therefore, lung cancer cells and lung cancer-associated fibroblasts (CAFs) are constantly exposed to mechanical load. Thus, to better explore the mechanisms involved in lung cancer progression, it is necessary to consider factors involved in cell mechanics, which may provide a more comprehensive analysis of tumorigenesis. The purpose of this review is: 1) to provide an overview of the anatomy and tissue characteristics of the lung and the presence of mechanical stimulation; 2) to summarize the role of mechanical stretching in the progression of lung cancer; and 3) to describe the relationship between mechanical stretching and the lung cancer microenvironment, especially CAFs.

An efficient semi-analytical static and free vibration analysis of laminated and sandwich beams based on linear elasticity theory

Based on the two-dimensional (2D) elastic theory without enforcing any beam assumption, an efficient semi-analytical scaled boundary finite element method (SBFEM) is proposed to solve the bending and free vibration responses of composite laminated and sandwich beams under the mechanical load. The scaled center is placed at infinity, which produces the accurate result by discretizing only the longitudinal direction of the beam structure treated as a one-dimensional (1D) discretization problem. A new kind of 1D high-order spectral element shape functions with the advantages of high accuracy and superior convergence is introduced in SBFEM coordinate system to approximate the geometric model and corresponding variables. The principle of weighted residual in conjunction with the Green’s theorem are applied to obtain the SBFEM governing equation of each layer with respect to radial displacement fields. The solution of equation is indicated analytically by a matrix exponential function, which can be accurately solved by using the precise integration technique (PIT). Finally, an effective and simple stiffness matrix is obtained. By comparing two examples with the solutions based on the finite element method (FEM), the results show that the proposed method has good accuracy and rapid convergence with only a few meshes. The numerical examples are given to investigate the parametric effects of the stacking sequence, thickness ratio, boundary condition, and load form on the variation of the displacement, stress and natural frequency. The results validate that the present technique is also applicable to the complex beam structure with softcore layer inside.

The Impact of Trace Elements on Osteoarthritis

Osteoarthritis (OA) is a progressive degenerative disease characterized by cartilage degradation, synovial inflammation, subchondral sclerosis and osteophyte formation. It has a multifactorial etiology with potential contributions from heredity, endocrine function, abnormal mechanical load and nutrition. Of particular considerations are trace element status. Several trace elements, such as boron and magnesium are essential for normal development of the bone and joint in human. While cadmium correlates with the severity of OA. The present review focuses on the roles of trace elements (boron, cadmium, copper, iron, magnesium, manganese, selenium, zinc) in OA and explores the mechanisms by which they act.

Analog and digital modeling of sound and impaired periodontal supporting tissues during mechanical testing

Periodontitis is one of the most common conditions affecting oral health among adults, posing a great challenge for both patients and also for dentists aiming to treat this disease. In severe stages such deterioration of the supporting tissues, namely the periodontal ligaments and the bone, can occur, which will affect the biomechanical behavior and therefore the longevity and survival of the affected teeth. In order to be able to plan both periodontal and subsequent restorative treatment properly, valid modelling of the current clinical situation is advised. The aim of the present article is to comprehensively discuss possible analog and digital modeling methods of periodontally affected teeth and the periodontal structures surrounding them. Modelling possibilities can serve later as the basis of mechanical load, digital finite element studies, and also aid clinical treatment planning.