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Double negative elastic metamaterials are a kind of novel artificial materials with unique ability to manipulate elastic wave propagation in the subwavelength scale. They are generally designed by inducing the combination of multiple resonance with different negative effective parameters. However, due to the limitation of empirical structural shape and design tools, these metamaterials are made by complex multiphase materials but possess a relatively narrow frequency range with double negativity, which is unsuitable for practical engineering applications. In this work, a shape optimization and single-phase chiral elastic metamaterials (EMMs) based strategy is presented for designing the EMMs with a broadband double negativity (negative mass density and bulk modulus). Several numerical examples are presented to validate the method by considering different initial shapes, target frequency ranges and design variables. Besides, numerical simulations related to double negativity including negative refraction and imaging are investigated by using the optimized chiral EMMs. Interestingly, elastic wave mode conversion and super-resolution imaging of 0.28λ are observed. The proposed metamaterial combined with the design approach is a very efficient way to obtain double negativity over a broad frequency band and it may thus have great potential for designing new elastic metamaterials.

The bi-directional evolutionary structural optimization (BESO) method has been widely studied and applied due to its efficient iteration and clear boundaries. However, due to the use of the discrete design variable, numerical difficulties are more likely to occur with this method, especially in cases with strong nonlinearity. This limits the application of the BESO method in certain cases, such as the suppression of structural dynamic frequency response under high-frequency excitation. In this work, a normalization strategy is proposed for the BESO-based topology optimization, by which the magnitude of the sensitivities can be efficiently unified to the same order to avoid the possible numerical instabilities caused by the nonlinearity. To validate its merit in applications, the normalization-based BESO (NBESO) method is proposed for minimizing the structural frequency response. By means of the weighted sum method, a normalized weighted sum method is also proposed for multi-frequency involved problems. A series of 2D and 3D numerical examples is presented to illustrate the advantages of the NBESO. The effectiveness of the NBESO for multi-frequency response suppression is also demonstrated, in which the frequency ranges below and above the eigenfrequency are involved, respectively.

Traditional finite element methods for the computation of the response of phononic crystals (PCs) with fluid-structure interaction (FSI) generally suffer from the dispersion error in the simulation, and the unavoidable uncertainties due to the manufactural errors and the material properties deviation. Therefore, it is important to develop an efficient numerical method to quantify the physical response of PCs with FSI. This paper presents a novel hybrid uncertain mass-redistributed finite element method (HUMR-FEM) to determine the uncertainty response of PCs with FSI. In this method, the MR-FEM is used to handle the FSI in PCs, which can minimize the dispersion error. The uncertainty of PCs is treated as random uncertainty with bounded distribution parameter instead of the precise values, and the response uncertainties are transformed into the deterministic computations of the extreme bounds of the statistical characteristics. Influences of the hybrid uncertainty on the physical responses in the design of PCs with FSI are discussed, and the accuracy and efficiency of the proposed method are validated through several numerical examples.

A non-contact acoustic pressure-based method is proposed for load identification in the acoustic structure interaction system involving non-probabilistic uncertainty. The forward problem for load identification is established through the discretized convolution integral relationship of the dynamic loads and the Green’s kernel function matrix of the system. The inverse process is constructed by using truncated single value decomposition approach in order to overcome the ill-posedness of the global kernel function matrix. In this work, two non-probabilistic models including ellipsoid model and interval model are proposed to quantify the effects of the system uncertainty. Several numerical examples are investigated to verify the effectiveness of the present methods. The results show that the non-contact acoustic pressure-based method with great convenience for dynamic load identification is accurate and effective. For the system with non-probabilistic uncertainty, the ellipsoid model and interval model are the proper choices to identify the bounds with knowing only the extreme values of the parameters. Moreover, the load bounds derived from the ellipsoid model are more reliable than those derived from the interval model.

Angiogenesis is the core step of wound repair, and vascular endothelial progenitor cells (EPC) play an extremely important role during wound repair. Recent studies have shown that vascular EPC-derived exosomes (EPC-Exo) can protect vessels, promote the proliferation and migration of vascular endothelial cells, and have anti-inflammatory, anti-oxidant and anti-apoptotic effects on vascular endothelial cells. This article reviews the mechanism of vascular EPC-Exo in angiogenesis and its potential applications in wound repair in recent years.血管新生是创面修复的核心步骤，血管内皮祖细胞(EPC)在其中发挥着极其重要的作用。新近研究显示，血管EPC源性外泌体(EPC-Exo)能保护血管，促进血管内皮细胞增殖、迁移及对血管内皮细胞具有抗炎、抗氧化及抗凋亡等作用。本文就近年来血管EPC-Exo在血管新生的作用机制及创面修复领域的潜在应用研究方面进行综述。.

The literature on evidence-based practice (EBP) in social work indicates a complex relationship between practitioners' attitudes, views on feasibility, and self-efficacy related to EBP implementation.Qualitative interviews and a self-report questionnaire were completed with 8 social work students. A conceptual framework of their perceptions was developed through thematic analysis.Participants reported mixed EBP attitudes, as both a practice "ideal", but also oppressive, rigid, and dehumanizing. Low confidence regarding research skills affected participants' self-efficacy. Resource constraints impacted feasibility through organizational culture and available practice-relevant research.EBP misconceptions critically impacted educational practices, organizational culture, and practitioners' attitudes. Comprehensive education mindful of professional identity may address misconceptions and enhance self-efficacy. EBP-enabling organizational change and practice-relevant research may alleviate resource constraints.Research should expand on how EBP attitudes and social work identity intersect, the impact of research skills on self-efficacy, and EBP barriers and facilitators in education and organizations.

耳鸣严重影响患者的生活质量，目前认为其产生机制与听觉通路信号改变所引起的神经元可塑性变化有关，其中可能涉及神经元兴奋性和抑制性传导失衡。A型γ-氨基丁酸受体（γ-aminobutyric acid a receptor,GABA(A)R）和N-甲基-D天冬氨酸受体（N-methyl-D-aspartic acid receptor,NMDAR）是重要的神经元抑制性和兴奋性受体，NMDAR功能亢进和GABA(A)R功能抑制可能是耳鸣发生中的关键性事件。钙/钙调蛋白激酶Ⅱ(Ca(2+)/calmodulin-dependent protein kinaseⅡ,Ca(2+)/CaMKⅡ）是一种丝氨酸/苏氨酸蛋白激酶，介导NMDAR和GABA(A)R的磷酸化及其相互作用，在神经突触受体活性调节过程中发挥重要作用，并可能参与耳鸣的发生发展过程。本文就Ca(2+)/CaMKⅡ介导NMDAR与GABA(A)R的相互作用及其与耳鸣的关系展开综述，并结合临床试验介绍相关耳鸣治疗最新研究成果，以期为临床耳鸣的治疗提供新的作用靶点和干预思路。.

Skin-stretching device as a new treatment method of wound closure has been recognized by many discipline fields. Through continuous improvement and adjustment in clinical application, it has achieved remarkable results in some departments. This article summarizes the basic theory, history, classification, and application of skin-stretching devices.皮肤牵张器作为目前临床上闭合创面的新兴治疗方法，已经获得多学科领域的认可，其在临床使用过程中历经不断改善和调整，已经在部分科室取得了显著疗效。本文主要就皮肤牵张器的基础理论、历史、分类及应用等进行综述。.

SummaryIntroduction As there is currently no complete cure for hemophilia A (HA), the identification of pathogenic mutations in factor VIII (FVIII) gene from HA patients and carriers, which can contribute to genetic counseling prenatal diagnosis, and preimplantation genetic diagnosis (PGD), is an important step to prevent HA. Methods A total of 14 unrelated Chinese HA subjects (FVIII activity C, c.304_305insA, c.1594T>A, c.6045G>A, and c.2645_2646insG) were found. The real-time PCR showed that the expression of FVIII mRNAs was lower in HA patients than in normal subjects. Prenatal diagnosis and PGD were successfully performed: Two of three fetuses and four of eight blastomeres were confirmed to be normal. Conclusion In conclusion, genetic diagnosis of 14 unrelated HA subjects, 20 carrier subjects, three fetuses, and one PGD was successfully performed in our study.

This paper studied a robust concurrent topology optimization (RCTO) approach to design the structure and its composite materials simultaneously. For the first time, the material uncertainty with imprecise probability is integrated into the multi-scale concurrent topology optimization (CTO) framework. To describe the imprecise probabilistic uncertainty efficiently, the type I hybrid interval random model is adopted. An improved hybrid perturbation analysis (IHPA) method is formulated to estimate the expectation and stand variance of the objective function in the worst case. Combined with the bi-directional evolutionary structural optimization (BESO) framework, the robust designs of the structure and its composite material are carried out. Several 2D and 3D numerical examples are presented to illustrate the effectiveness of the proposed method. The results show that the proposed method has high efficiency and low precision loss. In addition, the proposed RCTO approach remains efficient in both of linear static and dynamic structures, which shows its extensive adaptability.

The polarized energy dispersive X-ray fluorescence analysis method can effectively reduce detection limits by improving the signal-to-noise ratio. However, the lack of high-power density and small analysis area of the polarized X-ray beam has hindered more accurate analysis of samples in conventional laboratory. A polycapillary X-ray lens can be applied to micro-area analysis. Therefore, a micro-area polarized energy dispersive X-ray fluorescence spectrometer based on a bent highly oriented pyrolytic graphite and a polycapillary X-ray lens is proposed. The polarization degree of the polarized X-ray beam is 99.76% and its focal spot size is 338.8 μm × 404.5 μm. The new spectrometer feasibility was proved by effective production of high-resolution element distribution maps of a holly (Ilex chinensis Sims) leaf sample.

A simulation model is established to simulate the X-ray transmission performance through a polycapillary focusing X-ray lens whose configuration curve was described by a piecewise function. The shape of the lens is segmented, and each segment uses different function curve. The ray tracing principle is used to simulate the transmission performance of X-rays through the polycapillary focusing X-ray lens. And the simulation results were compared with the experimental results.

This study realized the microcell analysis using confocal area formed by a pair of polycapillary X-ray lens, built a 3D micro X-ray fluorescence spectrometer, elaborated the controlling software, and analyzed the 3D scan performance of the set-up via its measured and calculated basic parameters. The depth-detecting performance of the developed set-up was assessed by scanning several samples of Cu-Mo thin film on silicon base and red-green porcelain of Ming dynasty under different conditions. In addition, through surface-adaptive scanning, the scanning and identification of the fractures and fine cracks of the ceramic samples revealed the morphology of samples, which was consistent with the theoretical model.

Skin is the largest organ in the body, with a variety of functions, such as thermoregulation, physical barriers, and sensory transmission, etc. Therefore, to restore the function after injury as soon as possible is particularly important. Mesenchymal stem cells (MSCs) are derived from mesoderm, and can differentiate into a variety of tissues, such as cartilaginous tissue, myoideum, and adipose tissue. Weak immunogenicity of MSCs make them become the ideal seed cells of tissue engineering. MSCs have a wide range of sources, including known sources of bone marrow, skin, placenta, and adipose tissue, etc. MSCs from different sources also have many different mechanisms in wound repair. This article reviews the recent researches on MSCs in the treatment of chronic wounds, so as to explore new ideas for the clinical treatment of chronic wounds.

Dementia is a persistent disorder of the mental processes and is strongly related to depression. However, the performance of current antidepression medicine is far from satisfactory. Herbal extract provides an excellent source to identify compounds for possible drug development against depression. Here, HerboChips were employed to search herbal compounds that could bind nerve growth factor (NGF). By screening over 500 types of herbal extracts, the water extract of Ginkgo Folium, the leaf of Ginkgo biloba, showed a strong binding to NGF. The herbal fractions showing NGF binding were further isolated and enriched. By using LC-MS/MS analysis, one of the NGF binding fractions was enriched, which was further identified as quercetin, a major flavonoid in Ginkgo Folium. Quercetin, similar to Ginkgo Folium extract, could enhance the effect of NGF in cultured PC 12 cells, including potentiation of neurite outgrowth and phosphorylation of Erk-1/2. This is the first report of discovering an NGF binding compound by using HerboChips from herbal extracts, which could be further developed for antidepression application.

Introduction To reduce the incidence of hemophilia B (HB) which with no complete cure currently, prenatal diagnosis and preimplantation genetic diagnosis (PGD) are effective and feasible means. However, previous studies about genetic diagnosis in HB mostly just focused on the detection of patients and carriers. Here, we established a comprehensive genetic diagnosis strategy for HB and worked it out in Chinese population. The strategy includes the detection of patients and carriers, prenatal diagnosis, and PGD. Methods Seven unrelated HB families from Chinese population involved in this study. Firstly, probands and available members were carried out coagulation laboratory assays, and the clinical information has been recorded. Secondly, we used DNA direct sequencing to screen the whole FIX gene of them. The pathogenicity of novel mutations was verified according to 2015 ACMG-AM guidelines. For prenatal diagnosis, a mix of DNA direct sequencing and STR linkage analysis was employed. To explore a better PGD protocol, Karyomapping was first applied in PGD of HB, comparing with conventional PCR-based methods. Results Six different pathogenic mutations including 1 novel duplication (c.660_661dup ATCA) were identified. The results of prenatal diagnosis were consistent with birth outcomes. In the PGD case, 4 of 11 embryos were confirmed to be normal and one of them was transferred and led to a healthy birth. Conclusions The established genetic diagnosis strategy for HB in our study was comprehensive and well applied in clinic practice. Besides, we recommended that DNA direct sequencing combined with Karyomapping was a better PGD protocol.

The physical response of acoustic metamaterials may change due to the variation of the material properties in the manufacture process. Thus, an interval perturbation finite element method is formulated to study the mechanical response of acoustic metamaterials with the interval parameters, which includes the uncertainty effects on the band structure, resonance mode and frequency response of acoustic metamaterials. By virtue of the first-order Taylor series expansion and sensitivity analysis of dynamic properties of acoustic metamaterials with respect to the interval parameters, the interval perturbation finite element method established in this work can predict the upper and lower bounds of the dynamic properties of the acoustic metamaterials. Three numerical examples are studied to validate the effectiveness of the interval perturbation finite element method to analyze the physical response of acoustic metamaterials with the interval parameters, and the results calculated by Monte Carlo method are regarded as the reference results to validate the interval perturbation finite element method. The uncertainty model constructed by interval perturbation finite element method provides a great help in the design of acoustic metamaterials.

From application-oriented point of view, in order to decrease the cost of transportation the starch-based form was prepared by two steps: 1) compounding; and 2) foaming. That is because the foamed materials consist of more than 90% gas, the transportation cost could be higher than foam itself. In this work, starch-based pallets used for foaming were developed by extrusion. This presentation focuses on thermal and rheological properties of the starch-based materials. Cornstarch was used in this work. The results showed that the gelatinization temperature of the cornstarch was about 68°C with excess water content. The shear thin rheological behavior was observed for the cornstarch. Based on these the extrusion condition were designed and developed. In order to avoid foaming during compounding the temperature should be controlled less than 100°C. The higher screw speed can reduce the processing energy.

An inflammatory response induced by high glucose is a cause of endothelial dysfunction in diabetes and is an important contributing link to atherosclerosis. Diabetes is an independent risk factor of atherosclerosis and activation of retinoid X receptor (RXR) has been shown to exert anti-atherogenic effects. In the present study, we examined the effects of the RXR ligands 9-cis-retinoic acid (9-cis-RA) and SR11237 on high glucose-induced inflammation in human umbilical endothelial vein endothelial cells (HUVECs) and explored the potential mechanism. Our results showed that the inflammation induced by high-glucose in HUVECs was mainly mediated by the activation of nuclear factor-B (NF- κB). High glucose-induced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were in comparison, significantly decreased by treatment with RXR. The effect of RXR agonists was mainly due to the inhibition of NF-κB activation. Using pharmacological inhibitors and siRNA, we confirmed that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was an upstream activator of NF-κB. Furthermore, RXR agonists significantly inhibited high glucose-induced activation of NADPH oxidase and significantly decreased the production of reactive oxygen species (ROS). To explore whether the rapid inhibitory effects of RXR agonists were in fact mediated by RXR, we examined the effect of RXR downregulation by RXR siRNA. Our results showed that RXR siRNA largely abrogated the effects of RXR agonists, suggesting the requirement of RXR expression. Therefore, we have shown that RXR is involved in the regulation of NADPH oxidase- NF-κB signal pathway, as the RXR ligands antagonized the inflammatory response in HUVECs induced by high glucose.

At present, there is no ideal model for predicting the short-term outcome of patients with acute-on-chronic hepatitis B liver failure (ACHBLF). This study aimed to establish and validate a prognostic model by using the classification and regression tree (CART) analysis. A total of 1047 patients from two separate medical centres with suspected ACHBLF were screened in the study, which were recognized as derivation cohort and validation cohort, respectively. CART analysis was applied to predict the 3-month mortality of patients with ACHBLF. The accuracy of the CART model was tested using the area under the receiver operating characteristic curve, which was compared with the model for end-stage liver disease (MELD) score and a new logistic regression model. CART analysis identified four variables as prognostic factors of ACHBLF: total bilirubin, age, serum sodium and INR, and three distinct risk groups: low risk (4.2%), intermediate risk (30.2%-53.2%) and high risk (81.4%-96.9%). The new logistic regression model was constructed with four independent factors, including age, total bilirubin, serum sodium and prothrombin activity by multivariate logistic regression analysis. The performances of the CART model (0.896), similar to the logistic regression model (0.914, P=.382), exceeded that of MELD score (0.667, P

The present study investigated the effects of aluminum on lipid peroxidation, accumulation of reactive oxygen species and antioxidative defense systems in root tips of wheat (Triticum aestivum L.) seedlings. Exposure to 30 μM Al increased contents of malondialdehyde, H2O2, suproxide radical and Evans blue uptake in both genotypes, with increases being greater in Al-sensitive genotype Yangmai-5 than in Al-tolerant genotype Jian-864. In addition, Al treatment increased the activity of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), glutathione reductase (GR) and glutathione peroxidase (GPX), as well as the contents of ascorbate (AsA) and glutathione (GSH) in both genotypes. The increased activities SOD and POD were greater in Yangmai-5 than in Jian-864, whereas the opposite was true for the activities of CAT, APX, MDHAR, GR and GPX and the contents of AsA and GSH. Consequently, the antioxidant capacity in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH)-radical scavenging activity and ferric reducing/antioxidant power (FRAP) was greater in Jian-864 than in Yangmai-5.

The objective of this study was to examine the effect of the off axis retinoscopy on objective central refractive measurement in adult clinical practice.In all, 40 subjects underwent undilated retinoscopy in a randomly selected eye both on and off the visual axis by a single masked examiner. Off axis retinoscopy was defined as retinoscopy performed with the testing eye of the examiner aligned with the contralateral (non-test) eye of the subject resulting in an off axis deviation in the nasal horizontal visual field. Retinoscopy was performed in negative cylinder only and spherocylindrical measurements were converted to power vectors for analysis. Paired t-test was used to assess differences in M, J(0) and J(45) power vectors including differences between mean aided and unaided LogMar acuities.In all, 14 subjects were myopic (SE≤-0.5 D), 13 subjects were emmetropic (SE between -0.49 and 1.0 D) and 13 subjects were hyperopic (SE1.0 D). Mean angle of deviation was 5.58° in the nasal horizontal visual field. J(0) showed a significant negative shift in those with myopia (P0.001) and emmetropia (P=0.049) following off axis retinoscopy. No significant differences in M, J(0) and J(45) were found in the hyperopes. Mean aided LogMar acuities after on and off axis retinoscopy were both significantly better than mean unaided LogMar VA (P0.001 in both cases).Small degrees of off axis retinoscopy encountered in everyday clinical practice can induce errors in objective central refractive measurement.

In the contact problem of a rigid flat-ended punch on an elastic half-plane, the contact stress under punch is studied. The angle distribution for the stress components in the elastic medium under punch is achieved in an explicit form. From obtained singular stress distribution, the punch singular stress factor (abbreviated as PSSF) is defined. A fundamental solution for the multiple flat punch problems on the elastic half-plane is investigated where the punches are disconnected and the forces applied on the punches are arbitrary. The singular integral equation method is suggested to obtain the fundamental solution. Further, the contact problem for rigidly connected punches on an elastic half-plane is considered. The solution for this problem can be considered as a superposition of many particular fundamental solutions. The resultant forces on punches are the undetermined unknowns in the problem, which can be evaluated by the condition of relative descent between punches. Finally, the resultant forces on punches can be determined, and the PSSFs at the corner points can be evaluated. Numerical examples are given.

This paper investigates the dual boundary integral equation formulation in plane elasticity using a complex variable. Four kinds of BIE are studied, and they are: (1) the first complex variable BIE for the interior region, (2) the second complex variable BIE for the interior region, (3) the first complex variable BIE for the exterior region, and (4) the second complex variable BIE for the exterior region. Using the Somigliana identity and letting the domain point approach a boundary point, the first complex variable BIE is obtained. Displacement versus traction operator is suggested. Using this operator and letting the domain point approach a boundary point, the second complex variable BIE is obtained. When the domain point approaches a boundary point, all limit processes are performed exactly through the generalized Sokhotski–Plemelj’s formulae. For the exterior problems, two degenerate boundary cases, the curved crack and the deformable curved line, are studied. Particularly, for the degenerate boundary case, or the shrinking curved crack case, four kinds of BIE are obtained.

A novel method for load bounds identification for uncertain structures is proposed in the frequency domain. The uncertain parameters are assumed to locate in their intervals and only their bounds rather than their precise information are needed. To quantitatively describe the effect of the interval uncertainty on the load identification in the frequency ranges, the interval extension is then introduced in the frequency response function (FRF)-based least squares approach. Therefore, the load bounds are determined through the summation of the two separate parts including the midpoint part and the perturbed part of the load. The midpoint part is computed by using the Moore–Penrose pseudo-inversion and the perturbed part is transformed into the first derivatives of the midpoint load with respect to the uncertain parameters by applying the truncated total least squares (TTLS). Two numerical examples are investigated to validate that the proposed method is very effective to predict the load bounds for the uncertain structure in frequency domain.

This paper investigates the T-stress in a branch crack problem with infinitesimal branch length. The branch crack is composed of a main crack and many branches. The ratio of the lengths for branch to main crack is very small. A singular integral equation method is suggested to solve the problem numerically and the stress intensity factor and T-stress can be evaluated immediately. Many computed results for T-stress under different conditions for branches are presented. It is found from the computed results that the interaction for T-stress among branches is very complicated.

This paper investigates the degenerate scale problem for the Laplace equation in a multiply connected region with an outer elliptic boundary. Inside the elliptic boundary, there are many voids with arbitrary configurations. The problem is studied on the relevant homogenous boundary integral equation. The suggested solution is derived from a solution of a relevant problem. It is found that the degenerate scale and the eigenfunction along the elliptic boundary in the problem is the same as in the case of a single elliptic contour without voids, or the involved voids have no influence on the degenerate scale. The present study mainly depends on the integrations of two integrals, which can be integrated in closed form.

In the problem of thick-walled cylinders of functionally graded materials (FGMs), this paper chooses the displacement function as unknown in the governing equation. The Young’s modulus is arbitrary and constant Poisson’s ratio is assumed. Two fundamental solutions are defined from a numerical solution under two particular initial boundary conditions. In addition, the transmission matrix M is defined for the single layer case. The matrix relates the values of radical stress and displacement at the initial point to those at the end point of the layer. By using the matrix, the boundary value problem can be solved as well. After considering the continuation condition along the layers, the method of transmission matrix can also be used to the multiply-layered cylinder. The method of transmission matrix can also be used to solve the problem of the thick-walled sphere. A lot of numerical examples are presented.

This paper provides a formulation for indirect BIEs in plane elasticity using single or double layer potentials and complex variable. There are two ways to obtain two kinds of layer and the relevant indirect BIEs. In the first way, the displacement expression at domain point is directly obtained from the Somigliana identity with necessary modification. In the second way, after placing some density functions, for example, the body force or the dislocation doublet, along the layers, one can obtain the displacement expression at domain point. For both single and double layers, the continuous or discontinuous properties for the displacement and traction are studied in detail when a moving point is passing through the boundaries. Formulations of the Dirichlet and the Neumann problems are proposed. The ranges for solving the boundary value problem by using the single or double layer potentials are clearly indicated. For the case of single layer, the degenerate scale problems for the finite multiply connected region and infinite multiply connected region are studied. For the case of double layer, a hypersingular BIE for crack can be formulated by assuming that the density functions are vanishing along a portion of boundary.

Singular stress analysis in the flat punch problem of half-plane is carried out. The angle distribution for the stress components is also achieved in an explicit form. Followed a similar study in the punch analysis, the punch singular stress factor (abbreviated as PSSF) is defined from the singular stress distribution. For the problems of two punches or three punches, solutions in a closed form are obtained. The obtained solutions may depend on some complete elliptical integrals. Meantime, the exerting location of the resultant force for punches is also determined. Interactions between punches are also addressed. Several numerical examples with the calculated results are presented.

In this paper, a rigorous derivation for T-stress in line crack problem is presented. Similar to the edge crack case, this paper provides the T-stress dependence on loading with the Dirac delta function property.

The quality and safety of agricultural products is not only a major livelihood issues for people's health, but also the main barriers to international trade of agricultural products nowadays. The soil is the foundation to the production of agricultural products and the guarantee of agricultural development. The farmland soil quality is directly related to the quality and safety of agricultural products. Our country's soil has been polluted by a series of pollution, Such as the excessive discharge of industrial wastes, the encroachment of household waste, and the unreasonable use of pesticides and fertilizers. Soil degradation is a serious threat to the quality and safety of agricultural products, so eliminating soil degradation is the fundamental way out for quality and safety of agricultural products. By analyzing problems of the quality and safety of agricultural products in our country, and exploring the farmland soil influence on the quality and safety of agricultural products. This article provides a reference for improving the control level of quality and safety of agricultural products and the farmland soil quality.

This paper investigates the singular integral equation method for examining the stress intensity factor and the T-stress in the asymptotic solution of a kinked crack with an infinitesimal kink length. A numerical technique for the branch crack problem is introduced, which depends upon distribution of dislocation along the crack face. The technique reduces the branch crack problem to the solution of a singular integral equation. The kinked cracked problem can be considered as a particular case of the branch crack, and this problem can be solved by using the suggested technique. It is found from the computed results that the available asymptotic solution can give qualitatively correct results for stress intensity factors and the T-stress. In addition, the available asymptotic solution can only give sufficiently accurate results in a narrow range of the length of the kinked portion and the inclined kink angle.