Thin-walled beams are widely used in various industrial fields, and their bending collapse is one of the most important energy absorption mechanisms. Researchers have extensively explored the bending characteristics of thin-walled metallic beams with various configurations. Numerous experimental and numerical investigations have been carried out to analyze their deformation modes and evaluate the effects of key factors on their performance. Different approaches have been attempted to improve the energy absorption efficiency of thin-walled metallic beams under bending loads, including cellular material filling, composite wrapping, functionally graded thickness design, multi-cell or cellular sections, and arched profile design. This paper reviews the recent advances in the energy absorption responses of thin-walled metallic beams and their reinforced counterparts under bending collapse. The review aims to provide comprehensive resources for researchers and engineers to understand the progress in research on the bending behaviors of thin-walled beams, while inspiring innovative approaches for their analysis and design under bending loads.

Multi-cell thin-walled beams showed excellent energy absorption efficiency under various load conditions. However, the theoretical prediction of their bending resistance is quite a challenging task. In this work, the three-point bending collapse of thin-walled rectangular beams with single-, double-, and triple-cell sections is investigated experimentally and numerically. Two finite element schemes: the shell element scheme and the solid element scheme, are employed to simulate the experimental tests, and the features of the two schemes are compared. The influence of friction coefficients on the force response and deformation mode of the beams is analyzed. Finally, a constituent element method is proposed to predict the bending responses of multi-cell beams, and the feasibility of the method is demonstrated.

Let k>2 be an integer and P be a 2n×2n symplectic orthogonal matrix satisfying Pk = I2n and ker(Pj - I2n) = 0; 1≤j <k: For any compact convex hypersurface ∑⊂ℝ2n with n≥2 which is P-cyclic symmetric, i.e., x∈∑ implies Px∈∑ ; we prove that if ∑is (r;R)-pinched with R/r<(2k+2)/k,then there exist at least n geometrically distinct P-cyclic symmetric closed characteristics on ∑ for a broad class of matrices P:

A type of self-lock multi-cell tubes assembled by open section components is recently proposed to serve as energy absorbing devices. Due to the open feature of the section, the self-lock tubes with large width may develop global buckling mode under axial crushing and show much worse energy absorption performances. To overcome this drawback, expanded polystyrene (EPS) foam fillers are firstly employed to improve the stability of the structural deformation and to increase the energy absorption efficiency. Experiment results show that a 4% increase in mass by EPS foam leads to about 20% increase in energy absorption of the self-lock tube. Numerical analyses are also carried out to simulate the tests and analyze the structures with other enhancement methods including Al foam filling and tube enveloping. They may be employed separately or simultaneously. The combination method of Al foam filling and tube enveloping gets the highest energy absorption capacity and efficiency. Theoretical analysis is performed to predict the mean crushing force of self-lock tubes enhanced by Al foam filling and tube enveloping, and the theoretical results compare well with numerical results. Finally, crashworthiness optimization problems are proposed and solved to explore the optimal enhancement configurations of the self-lock multi-cell tubes.

A new type of self-locking multi-cell structure fabricated by assembling four C-shaped open sections is proposed in this paper. Quasi-static and dynamic experimental tests are performed to investigate the axial crush resistance and energy absorption characteristics of this type of structures. The experiment results show that the SEA of the assembled multi-cell sections is 35-40% and 40-50% higher than that of the constituent C-shaped elements for quasi-static and dynamic loading, respectively. Numerical analyses are carried out to simulate the experiment and perform the parametric study on the influences of geometric parameters, boundary condition and load speed on the crush resistance of structures. The behavior and performance of single C-shaped open sections are also studied, and the interaction effects originated from the self-locking features are investigated quantitatively. In addition, theoretical expressions are derived to predict the crush resistance of the assembled self-locking multi-cell sections. Comparisons show that the theoretical expressions can predict the static and dynamic mean crushing forces of the self-locking multi-cell structures with errors below 5% in most cases.

The double-hat-shaped magnesium tube was difficult to use in actual applications due to its frangible material property. Magnesium alloy and traditional steel were integrated into a new hybrid thin-walled double-hat-shaped tube to improve vehicle crashworthiness. Two classes of hybrid tubes were examined, namely Hybrid-I (steel top hat and magnesium alloy bottom hat) and Hybrid-II (magnesium alloy top hat and steel bottom hat). The energy absorption characteristics and crashworthiness optimization of the thin-walled hybrid structures were investigated under three-point bending conditions through experiments and simulations. Multi-objective optimization design for the two hybrid tubes was implemented to elucidate their lightweight properties. Results showed that the specific energy absorption of Hybrid-I tube and Hybrid-II tube was approximately 44.7% and 12.7% higher than that of the double-hat-shaped DC04 tube, respectively. The Hybrid-I tube had better crashworthiness and lightweight properties compared with Hybrid-II tube. Hybrid-I tube also had better lightweight properties than single-material steel tube and reduced wall thickness compared with magnesium alloy tube.

The aim of the present retrospective analysis was to determine the effectiveness of pelvic radiotherapy (RT) as postoperative adjuvant therapy for low-risk cervical cancer. Between June 2003 and April 2011, the clinical data of 225 International Federation of Gynecology and Obstetrics (FIGO) Stage IB1-IIA cervical cancer patients with low-risk factors were retrospectively reviewed, to analyze the relationship between adjuvant pelvic RT after radical hysterectomy and tumor recurrence or the patients' survival. The 5-year overall survival (OS) of 225 patients was 91.2% and 5-year disease-free survival (DFS) was 84.5%. The 5-year DFS and local regional disease-free survival was significantly better for patients in the RT group compared with that in the non-RT group (5-year DFS, 91.2% vs. 77.1%, P = 0.006; 5-year local regional disease-free survival 94.6% vs. 79.0%, P = 0.001). There were no statistically significant differences in the 5-year OS (92.9% vs. 89.4%, P = 0.371) and distant metastasis-free survival (96.4% vs. 96.5%, P = 0.887) between the two groups. Grade 3-4 treatment-related acute and late toxicities were not significantly different between the two groups. Subgroup analysis shows the 5-year DFS of RT alone, chemotherapy (CT) alone, non-RT/CT, RT and CT was, respectively, 90.5%, 62.9%, 81.4%, 92.5% separately (P = 0.002). The 5-year OS was not significantly different (91.6% vs. 78.2% vs. 92.9% vs. 96.9%, P = 0.887) between the four groups. Performing univariate analysis, postoperative CT was the only significant risk factor for DFS. Our results indicate that postoperative adjuvant pelvic RT has a tendency to improve DFS especially local regional disease-free survival for FIGO Stage IB1-IIA cervical cancer patients with low-risk factors, without increased Grade 3-4 treatment-related acute and late toxicities, but non-standard CT is harmful to the prognosis (DFS) of these patients.

This paper describes an automatic and accurate segmentation method to extract the acetabulum tissue from sequential CT images. The hip joint consists of acetabulum and femoral head. In the personalized femoral head prosthesis designing by reverse engineering technology, obtaining the accurate acetabulum shape is the most important task. However, due to the necrotic femoral head's complex shape and the extremely narrow inter-bone region, obtaining the accurate acetabulum shape remains a challenging work. In this paper, we overcame these difficulties and developed an automatic segmentation method. First, we obtain the rough contour of the femoral head by utilizing the constraints of the great trochanter and the shape of femoral head in the initial slice. Second, we refine the rough contour by an orthogonal line edge detection approach and obtain a refined contour which will be used as the initial contour of the snake algorithm. Then, the snake algorithm is performed slice by slice upwards and downwards to generate the adjacent contours. During this process, the contour of the femoral head in a segmented slice is used as the initial contour of the next unsegmented slice. Finally, we can obtain the accurate sequential contours of the acetabulum by removing the femoral head and the femoral regions. And the 3D models of the acetabulum can be obtained correspondingly. The experimental result shows that the 3D models obtained by the proposed method are accurate and satisfactory. On this condition, we can reconstruct the personalized femoral head 3D models and design the personalized femoral head prosthesis.

Ischaemia/reperfusion (I/R) injury will cause additional death of cardiomyocytes in ischaemic heart disease. Recent studies revealed that renalase was involved in the I/R injury. So, the myocardial tissue-specific knockdown mouse models were needed for the investigations of renalase. To establish the mouse models, intramyocardial injection of siRNAs targeting renalase was performed in mice. The wild distribution and high transfection efficiency of the siRNAs were approved. And the renalase expression was efficiently suppressed in myocardial tissue. Compared with the high cost, time consumption, and genetic compensation risk of the Cre/loxP technology, RNA interference (RNAi) technology is much cheaper and less time-consuming. Among the RNAi technologies, injection of siRNAs is safer than virus. And considering the properties of the I/R injury mouse models, the efficiency and durability of injection with siRNAs are acceptable for the studies. Altogether, intramyocardial injection of siRNAs targeting renalase is an economical, safe, and efficient method to establish myocardial tissue-specific renalase knockdown mouse models.

The interleukin-1 family of cytokines are potent inducers of inflammation and pain. Proteolytic activation of this family of cytokines is under the control of several innate immune receptors that coordinate to form large multiprotein signalling platforms, termed inflammasomes. Recent evidence suggests that a wide range of inflammatory diseases, cancers, and metabolic and autoimmune disorders, in which pain is a common complaint, may be coordinated by inflammasomes. Activation of inflammasomes results in cleavage of caspase-1, which subsequently induces downstream initiation of several potent pro-inflammatory cascades. Therefore, it has been proposed that targeting inflammasome activity may be a novel and effective therapeutic strategy for these pain-related diseases. The purpose of this narrative review article is to provide the reader with an overview of the activation and regulation of inflammasomes and to investigate the potential therapeutic role of inflammasome inhibition in the treatment of diseases characterized by pain, including the following: complex regional pain syndrome, gout, rheumatoid arthritis, inflammatory pain, neuropathic pain, chronic prostatitis, chronic pelvic pain syndrome, and fibromyalgia. We conclude that the role of the inflammasome in pain-associated diseases is likely to be inflammasome subtype and disease specific. The currently available evidence suggests that disease-specific targeting of the assembly and activity of the inflammasome complex may be a novel therapeutic opportunity for the treatment of refractory pain in many settings.

The multi-instance multi-label (MIML) learning is a learning framework where each example is described by a bag of instances and corresponding to a set of labels. In some studies, the algorithms are applied to natural scene image classification and have achieved satisfied performance. We design a MIML algorithm based on RBF neural network for the natural scene image classification. In the framework, we compare classification accuracy based on the existing definitions of bag distance: maximum Hausdorff, minimum Hausdorff and average Hausdorff. Although the accuracy of average Hausdorff bag distance is the highest, we find average Hausdorff bag distance to weaken the role of the minimum distance between the instances in the two bags. So we redefine the average Hausdorff bag distance by introducing an adaptive adjustment coefficient, and it can change according to the minimum distance between the instances in the two bags. Finally, the experimental results show that the enhanced algorithm has a better result than the original algorithm.

For curing the worldwide disease — avascular necrosis of femoral head, the matching quality between the femoral head prosthesis and the acetabulum plays an important role in the operative treatment of the artificial femoral head replacement. In order to obtain a more accurate model of the femoral head prosthesis for the specified patient, a new personalized modeling system is presented in this paper. It is different from our previous system based on the sphere fitting method. This new system can reconstruct a more accurate ellipsoid model of the femoral head for the specified patient. It can recover the necrotic femoral heads into the satisfactory models. These models can well match with the acetabulum. Also, the static and dynamic matching error analyses for the reconstructed models can be implemented in this system. This new system can give a theoretical model for the accurate operation locating in the treatment of artificial femoral head replacement. And this system also provides an innovative practical means for the personalized modeling of the artificial femoral head before the prosthesis manufacture procedure.

Multi-cell columns are highly efficient energy absorbing components under axial compression. However, the experimental investigations and theoretical analyses for the deformation modes and mechanisms of them are quite few. In this paper, the axial crushing of circular multi-cell columns are studied experimentally, numerically and theoretically. Circular multi-cell columns with different sections are axially compressed quasi-statically and numerical analyses are carried out by nonlinear finite element code LS-DYNA to simulate the experiments. The deformation modes of the multi-cell columns are described and the energy absorption properties of them are compared with those of simple circular tube. Theoretical models based on the constituent element method are then proposed to predict the crush resistance of circular multi-cell specimens. The theoretical predictions are found to be in a good agreement with the experimental and numerical results.

Introducing thickness gradient in cross-section is a quite promising approach to increase the energy absorption efficiency and crashworthiness performance of thin-walled structures. This paper addresses the deformation mode and energy absorption of square tubes with graded thickness during axial loading. Experimental study is firstly carried out for square tubes with two types of thickness distributions and numerical analyses are then conducted to simulate the experiment. Both experimental and numerical results show that the introduction of graded thickness in cross-section can lead to up to 30–35% increase in energy absorption efficiency (specific energy absorption) without the increase of the initial peak force. In addition, structural optimization of the cross-section of a square tube with graded thickness is solved by response surface method and the optimization results validate that increasing the material in the corner regions can indeed increase the energy absorption efficiency of a square tube.

Commercial aluminum honeycombs with various cell configurations are experimentally tested to study the influence of cell number and central angle on the out-of-plane crush resistance of the structures. The boundary effect is found to have significant impact on the crush strength of the structure when the number of cells is small and the central angle is observed to get a difference less than 10% in the strength of the honeycombs. Numerical analyses based on whole honeycomb model and Y-shaped element model are carried out to simulate the crush and deformation process of the specimens. The adhesive bonding of the double thickness foil is considered in the simulation and the numerical results show good agreement with the experimental data and theoretical predictions. Finally, the reason for the small influence of central angle on the out-of-plane strength of honeycombs is investigated and the interaction effect between wall thickness and central angle is believed to account for it.

Multi-cell metal columns were found to be much more efficient in energy absorption than single-cell columns under axial compression. However, the experimental investigations and theoretical analyses of them are relatively few. In this paper, the quasi-static axial compression tests are carried out for multi-cell columns with different sections. The significant advantage of multi-cell sections over single cell in energy absorption efficiency is investigated and validated. Numerical simulations are also conducted to simulate the compression tests and the numerical results show a very good agreement with experiment. Theoretial analyses based on constitutive element method are proposed to predict the crush resistance of multi-cell columns and the theoretical predictions compare very well with the experimental and numerical results.

The present work is aimed at finding the maximum energy absorption efficiency of plates in thin-walled structures under compression. In thin-walled structures, the plates are connected with different angles and by different edge connectivity. The influences of these two major factors on the crush resistance of structures are investigated numerically by nonlinear finite element code. Two extreme modes: uniform mode and opposite mode are defined for the angle elements with different edge connectivity. The energy absorption characteristics of these two modes are investigated and a theoretical model is established to predict the energy absorption capacity of elements deforming in uniform mode. Experimental tests of multi-cell columns are conducted to validate the numerical analyses and theoretical models for angle elements. The numerical simulations and theoretical predictions of the crush resistance of multi-cell columns show a very good agreement with the experimental results.

Energy absorption characteristics of regular polygonal columns and rhombic columns under quasi-static axial compression are investigated by using an INSTRON materials testing machine. The influence of central angle on deformation mode and mean crushing force of angle elements is studied. Numerical investigations are also carried out to study the crush resistance of polygonal columns and angle elements under quasi-static and dynamic axial compression. The numerical predicted crushing force and deformation mode of the polygonal columns are found to be in good agreement with the experimental results. In addition, based on the experiment observations, some discussion about the deformation mechanism of energy absorption is presented.

The classical and alternative activation of macrophages has been proposed to play a role in radiation-induced pneumonitis and fibrosis, respectively. To test this hypothesis, the thoraces of C57BL/6 mice were irradiated with 12 Gy X-rays, and irradiated and control mice were euthanized at 1, 8, 12, 24 and 72 hours, and 2, 4, 8, 16 and 24 weeks after irradiation. The expression of inducible nitric oxide synthase (iNOS) and arginase type 1 (Arg-1) was evaluated at the mRNA and protein levels at different stages post-irradiation. We demonstrated that the enhanced mRNA and protein expression of iNOS occurred within the pneumonic stage, whereas the high levels of Arg-1 expression occurred within the fibrotic phase. Immunohistochemistry revealed that iNOS and Arg-1 were mainly expressed in macrophages. The expression of iNOS and Arg-1 may be associated with acute radiation pneumonitis and the development of radiation fibrosis, respectively. Although the function of macrophages cannot explain the whole process of radiation-induced pulmonary injury development, it may play an important regulatory role during this process.