Search Results (64)

Osteoarthritis (OA) is a prevalent and debilitating joint disease in older adults with a complex etiology. We investigated the role of SUMOylation, a post-translational modification, in OA pathogenesis, focusing on the mitochondrial chaperone Prohibitin (PHB1) and the cartilage homeostasis transcription factor PITX1. We hypothesized that oxidative stress-induced SUMOylation promotes PHB1 nuclear accumulation, leading to PITX1 downregulation and contributing to OA development. Analysis of cartilage specimens from 27 OA patients and 4 healthy controls revealed an increased nuclear accumulation of PHB1 in OA chondrocytes, accompanied by elevated levels of SUMO-1 and SUMO-2/3. Mechanistically, nuclear PHB1 interacted indirectly with SUMO-1 through a SUMO-interacting motif (SIM), and the deletion of this SIM prevented PHB1 nuclear trapping in OA cells. Furthermore, the SUMO-conjugating enzyme E2 (UBC9) encoded by the UBE2I gene was upregulated in knee OA cartilage, and its overexpression in vitro enhanced PHB1 nuclear accumulation. Consistently, transgenic mice overexpressing the Ube2i gene exhibited increased UBC9 in their knee cartilage, resulting in Pitx1 downregulation and the emergence of an early OA-like phenotype in articular chondrocytes. Our findings uncover a novel role for UBC9-mediated SUMOylation in primary knee and hip OA. This pathway enhances PHB1 nuclear accumulation, contributing to PITX1 repression and subsequent OA development. These results underscore the importance of SUMOylation in OA pathogenesis and suggest potential molecular targets for early diagnosis and therapeutic intervention. Full article

The Jinchuan area is located along the northeastern margin of Longshou Shan, in the western part of the North China Plate. Since the Paleoproterozoic period, it has undergone complex geological evolution. A systematic analysis of the tectonic evolution in this region reveals key information about the tectonic background and evolutionary characteristics since the Paleoproterozoic period and serves as a crucial approach for understanding metallogenic processes and achieving breakthroughs in deep mineral exploration. Based on detailed field investigations, this study analyzes the structural characteristics of the area, focusing on conjugate shear joints, folds, and faults. Combined with previous research findings, the evolution of the tectonic stress field is analyzed. The results indicate that the orientation of the maximum principal stress underwent the following six distinct phases of change: nearly north-south (NS) → nearly east-west (EW) → nearly north-south (NS) → north-northeast-south-southwest (NNE-SSW) → northwest-southeast (NW-SE) → northeast-southwest (NE-SW). Integrating these results with the regional tectonic framework, the study systematically reconstructs the tectonic evolution of the Jinchuan area. This research provides important scientific insights and practical value for enhancing geological understanding of the region and guiding mineral resource exploration and development. Full article

In this article, an improved real-valued dimension-reduction MUSIC (IRDR-MUSIC) algorithm is proposed for a crossed-dipole array. Initially, conjugate symmetry of the spatial component in the manifold vector is derived such that two real-valued matrices for the sum and difference covariance are constructed, which consist of the real and imaginary parts of the complex covariance matrix respectively. However, sum and difference covariance matrices with information loss would deteriorate the performance. Thus, given that the sum and difference covariance matrices have an identical null space, a joint sum–difference covariance matrix combining both the sum and difference covariance matrices is constructed, which includes the complete information of a complex covariance matrix. Accordingly, a computationally efficient IRDR-MUSIC algorithm with an enhanced performance is proposed. Compared with the existing dimension-reduction MUSIC algorithm, the proposed IRDR-MUSIC algorithm greatly reduce the complexity reduction almost without any performance loss since singular-value decomposition of the joint sum–difference covariance matrix operates in the real-valued domain, and only half of the range of the spatial spectrum search is required. Furthermore, the proposed IRDR-MUSIC algorithm outperforms the state-of-art complex-valued, symmetry-compressed, dimension-reduction MUSIC algorithm in both its multi-target resolution and computational efficiency. Numerical simulations and analyses verify the superiority of the proposed IRDR-MUSIC algorithm. Full article

A harmonic drive (HD) is a precision reduction device widely utilized in the core joints of high-end equipment such as spacecraft and robots. The design of an excellent tooth profile is the core challenge related to the performance of HD. This investigation aims to propose a design method of a fully conjugated cycloid tooth profile (CTP) for HD. Firstly, the rationality of CTP use for HD is analyzed, and the cycloidal characteristics of the tooth trajectory are studied by use of canonical warping distance. Then, initial CTP equations are constructed, adopting the trajectory mapping results. Presetting the addendum CTP of circular spline, the conjugate CTP of flexspline is then designed using the envelope method. Subsequently, the envelope of the designed flexspline addendum is used to reverse-design the circular spline dedendum. The backlash is calculated to evaluate the CTPs designed with different radial displacement coefficients. Research shows that the tooth trajectory has cycloidal characteristics; therefore, the HDs that use CTP can realize a fully conjugate engagement. Moreover, the variable control parameters enable the proposed CTP expression to have excellent fitting characteristics, resulting in small and uniform mesh backlash distribution. The CTP is expected to become one of the ideal tooth profiles of HD. Full article

Chronic immunoinflammatory rheumatic diseases, such as axial spondyloarthritis (AxSpA), are accompanied by a dysregulation of bone remodeling. Among potential biomarkers of bone metabolism, the Wnt pathway antagonist, Dickkopf-1 (DKK-1), is of particular interest because of its potential to reflect a shift towards joint ossification or osteoporosis, but its diagnostic value needs validation. There is still a lack of stable and efficient methods of measuring serum DKK-1 levels suitable for longitude studies. The use of aptamer-based diagnostic assays could be very promising for this purpose. We generated novel anti-DKK-1 DNA aptamers from a combinatorial library with a pre-defined sequence pattern in the randomized region. This approach showed high efficacy, as only four SELEX rounds of selection produced high-affinity aptamers with dissociation constants ranging from 1.3 to 3.7 nM. A family of their truncated versions was also developed by rational design. Novel DNA aptamers functioned as capture components in a microplate ELISA-like assay with HRP-conjugated anti-DKK-1 antibody as a reporter component. We succeeded in revealing the aptamer/aptamer sandwich pairs that provided an aptamer-only sandwich colorimetric assay. The aptamer/antibody colorimetric test systems were also examined in the analyses of blood serum from AxSpA patients and shown sufficient workability. However, in a number of cases we registered significant differences between assays based on TD10 and DK4 aptamers and made some suggestions about the origin of this effect. Full article

A spatial problem of elasticity theory is solved for a layer located on two bearings embedded in it. The bearings are represented as thick-walled pipes embedded in the layer parallel to its boundaries. The pipes are rigidly connected to the layer, and contact-type conditions (normal displacements and tangential stresses) are specified on the insides of the pipes. Stresses are set on the flat surfaces of the layer. The objective of this study is to obtain the stress–strain state of the body of the layer under different geometric characteristics of the model. The solution to the problem is presented in the form of the Lamé equation, whose terms are written in different coordinate systems. The generalized Fourier method is used to transfer the basic solutions between coordinate systems. By satisfying the boundary and conjugation conditions, the problem is reduced to a system of infinite linear algebraic equations of the second kind, to which the reduction method is applied. After finding the unknowns, using the generalized Fourier method, it is possible to find the stress–strain state at any point of the body. The numerical study of the stress state showed high convergence of the approximate solutions to the exact one. The stress–strain state of the composite body was analyzed for different geometric parameters and different pipe materials. The results obtained can be used for the preliminary determination of the geometric parameters of the model and the materials of the joints. The proposed solution method can be used not only to calculate the stress state of bearing joints, but also of bushings (under specified conditions of rigid contact without friction on the internal surfaces). Full article

The development of fractures under multiple geological tectonic movements affects the occurrence and efficient production of free gas in deep coal reservoirs. Taking the No.8 deep coal seam of the Benxi formation in the Linxing area as the object, a method for evaluating favorable fracture areas is established based on the combination of field joint staging, paleogeological model reconstruction under structural leveling, finite element numerical simulation, and fracture development criteria. The results show that a large number of shear fractures and fewer tensile joints are developed in the Benxi formation in the field and mainly formed in the Yanshanian and Himalayan periods. The dominant strikes of conjugate joints in the Yanshanian period are NWW (100°~140°) and NNW (150°~175°), with the maximum principal stress magnitude being 160 MPa along the NW orientation. Those in the Himalayan period are in the NNE direction (0°~40°) and the EW direction (80°~110°), with the maximum principal stress magnitude being 100 MPa along the NE orientation. The magnitudes of the maximum principal stress of the No. 8 deep coal seam in the Yanshanian period are between −55 and −82 MPa, indicative of compression; those in the Himalayan period are from −34 to −70 MPa in the compressive stress form. Areas with high shear stress values are mainly distributed in the central magmatic rock uplift, indicating the influence of magmatic rock uplift on in situ stress distribution and fracture development. Based on the comprehensive evaluation factors of fractures, the reservoir is divided into five classes and 24 favorable fracture areas. Fractures in Class I areas and Class II areas are relatively well developed and were formed under two periods of tectonic movements. The method for evaluating favorable fracture areas is not only significant for the prediction of fractures and free gas contents in this deep coal reservoir but also has certain reference value for other reservoirs. Full article

As the second-generation high-temperature superconducting conductors, rare earth–barium–copper–oxide (REBCO) coated conductor (CC) tapes have good potential as high-field and high-energy superconductors. In superconducting applications, several joints are required for conjugating comparatively short REBCO CC tapes. Soldering lap joints are the simplest and most commonly applied REBCO CC joints. In addition to joint resistance, the mechanical behavior and electromechanical properties are also crucial for superconducting applications. In this paper, the electromechanical properties and mechanical behaviors of soldering lap joints at 77 K under a self-field were studied. The mechanical behavior was addressed by using a full three-dimensional multilayer elastic–plastic finite element model (FEM) with REBCO CC tape main layers and solder connecting layers. Then, the electromechanical properties were analyzed by using Gao’s strain-$I_c$ degradation general model on the basis of the FEM results. Both the mechanical behavior and electromechanical properties were verified by experimental results. The effects of soldering lap conditions including lap length, soldering thickness and lap style on the electromechanical properties and mechanical behaviors were discussed. The results indicate that shorter overlap lengths and a thinner solder can reduce the premature degradation of I_c due to stress concentrations nearby the joint edges; moreover, the irreversible critical strain is significantly higher in the back-to-back joint approach compared to the widely used face-to-face joint approach. Full article

A restricted form of Landauer’s principle, independent of computational considerations, is shown to hold for thermal systems by reference to the joint entropy associated with conjugate observables. It is shown that the source of the compensating entropy for irreversible physical processes is due to the ontological uncertainty attending values of such mutually incompatible observables, rather than due to epistemic uncertainty, as traditionally assumed in the information-theoretic approach. In particular, it is explicitly shown that erasure of logical (epistemic) information via reset operations is not equivalent to erasure of thermodynamic entropy, so that the traditional, information-theoretic form of Landauer’s principle is not supported by the physics. A further implication of the analysis is that, in principle, there can be no Maxwell’s Demon in the real world. Full article

Signal detection in massive MIMO systems faces many challenges. The minimum mean square error (MMSE) approach for massive multiple-input multiple-output (MIMO) communications offer near to optimal recognition but require inverting the high-dimensional matrix. To tackle this issue, a Gauss–Seidel (GS) detector based on conjugate gradient and Jacobi iteration (CJ) joint processing (CJGS) is presented. In order to accelerate algorithm convergence, the signal is first initialized using the optimal initialization regime among the three options. Second, the signal is processed via the CJ Joint Processor. The pre-processed result is then sent to the GS detector. According to simulation results, in channels with varying correlation values, the suggested iterative scheme’s BER is less than that of the GS and the improved iterative scheme based on GS. Furthermore, it can approach the BER performance of the MMSE detection algorithm with fewer iterations. The suggested technique has a computational complexity of O(U²), whereas the MMSE detection algorithm has a computational complexity of O(U³), where U is the number of users. For the same detection performance, the computational complexity of the proposed algorithm is an order of magnitude lower than that of MMSE. With fewer iterations, the proposed algorithm achieves a better balance between detection performance and computational complexity. Full article

Significant progress has been made in vaccine development worldwide. This study examined the WHO African Region’s vaccine introduction trends from 2000 to 2022, excluding COVID-19 vaccines. We extracted data on vaccine introductions from the WHO/UNICEF joint reporting form for 17 vaccines. We examined the frequency and percentages of vaccine introductions from 2000 to 2022, as well as between two specific time periods (2000–2010 and 2011–2022). We analysed Gavi eligible and ineligible countries separately and used a Chi-squared test to determine if vaccine introductions differed significantly. Three vaccines have been introduced in all 47 countries within the region: hepatitis B (HepB), Haemophilus influenzae type b (Hib), and inactivated polio vaccine (IPV). Between 2011 and 2022, HepB, Hib, IPV, the second dose of measles-containing vaccine (MCV2), and pneumococcal conjugate vaccine (PCV) were the five most frequently introduced vaccines. Hepatitis A vaccine has only been introduced in Mauritius, while Japanese encephalitis vaccine has not been introduced in any African country. Between 2000–2010 and 2011–2022, a statistically significant rise in the number of vaccine introductions was noted (p < 0.001) with a significant positive association between Gavi eligibility and vaccine introductions (p < 0.001). Significant progress has been made in the introduction of new vaccines between 2000 and 2022 in the WHO African Region, with notable introductions between 2011 and 2022. Commitments from countries, and establishing the infrastructure required for effective implementation, remain crucial. Full article

Many optoelectronic applications require organic semiconductor (OSC) materials with high electron affinity. In this work, a series of novel acceptor–donor–acceptor (A–D–A) materials with low-lying LUMO energy levels were designed and characterized. In this strategy, two acceptor dyes, bis-isatin and di-2-(2-oxindolin-3-ylidene) malononitrile, were connected by various π–bridges (benzene ring, benzo[c][1,2,5]thiadiazole, monothiophene, trithiophene). We varied the length of the π–conjugation of the central core and the linkage position of the acceptor core (4- vs. 6-position of the phenyl ring) to investigate the effect on the optical and electrochemical properties of the materials. We performed density functional theory (DFT) and time-dependent DFT (TD–DFT) studies to gain insight into the dyes’ electronic properties by determining the energy levels. Our findings demonstrate that with increasing acceptor strength and π–conjugation length of the core, the wavelength of the longest absorption maximum as well as their respective extinction coefficients are enhanced, which results in band-gap reduction either by lowering the LUMO and/or raising the HOMO energy level of the molecules. The potential practical utility of these materials as electron-transport materials for perovskite solar cells (PSCs) has been demonstrated. Full article

In this paper, force sensor signals are classified using a pattern recognition neural network (PRNN). The signals are classified to show if there is a collision or not. In our previous work, the joints positions of a 2-DOF robot were used to estimate the external force sensor signal, which was attached at the robot end-effector, and the external joint torques of this robot based on a multilayer feedforward NN (MLFFNN). In the current work, the estimated force sensor signal and the external joints’ torques from the previous work are used as the inputs to the proposed designed PRNN, and its output is whether a collision is found or not. The designed PRNN is trained using a scaled conjugate gradient backpropagation algorithm and tested and validated using different data from the training one. The results prove that the PRNN is effective in classifying the force signals. Its effectiveness for classifying the collision cases is 92.8%, and for the non-collisions cases is 99.4%. Therefore, the overall efficiency is 99.2%. The same methodology and work are repeated using a PRNN trained using another algorithm, which is the Levenberg–Marquardt (PRNN-LM). The results using this structure prove that the PRNN-LM is also effective in classifying the force signals, and its overall effectiveness is 99.3%, which is slightly higher than the first PRNN. Finally, a comparison of the effectiveness of the proposed PRNN and PRNN-LM with other previous different classifiers is included. This comparison shows the effectiveness of the proposed PRNN and PRNN-LM. Full article

Generalized progressive hybrid censoring approaches have been developed to reduce test time and cost. This paper investigates the difficulties associated with estimating the unobserved model parameters and the reliability time functions of the Kavya Manoharan Kumaraswamy (KMKu) distribution based on generalized type-II progressive hybrid censoring using classical and Bayesian estimation techniques. The frequentist estimators’ normal approximations are also used to construct the appropriate estimated confidence intervals for the unknown parameter model. Under symmetrical squared error loss, independent gamma conjugate priors are used to produce the Bayesian estimators. The Bayesian estimators and associated highest posterior density intervals cannot be derived analytically since the joint likelihood function is provided in a complicated form. However, they may be evaluated using Monte Carlo Markov chain (MCMC) techniques. Out of all the censoring choices, the best one is selected using four optimality criteria. Full article

Flexure hinges are widely used in mechanical devices, especially for micro- or even nano-scale applications, where conventional joints based on conjugate surfaces prove unsuitable. However, to achieve accurate motion of devices whose joints are flexure hinges, knowledge of stiffness models that correlate applied forces or bending moments with the resulting displacements is required. Nonlinear bending models are typically too complex and difficult to implement. Therefore, it is preferred to use linear models, which admit analytical solutions. The purpose of this paper is to show what is lost in terms of accuracy in reducing a nonlinear bending stiffness model associated with a flexure hinge when simplifications are made to obtain an analytical solution. An analysis of the simplification process leading to a linear stiffness model and its analytical solution is presented. From this study arises an increased awareness of flexure joints in terms of the accuracy obtained with their stiffness models, suggesting important information to the user in choosing the level of complexity required to model them in a specific application. A comparison between analytical and numerical results is provided in the form of maps and tables so as to make that choice as clear as possible. Full article