Dynamic parameter identification and adaptive control with trajectory scaling for robot-environment interaction.

To improve the force/position control performance of robots in contact with the environment, this paper proposes a control scheme comprising dynamic parameter identification, trajectory scaling, and computed-torque control based on adaptive parameter estimation. Based on the Newton-Euler method, the dynamic equation and its regression matrix is obtained, which is helpful to reduce the order of the model. Subsequently, the least-square method is implemented to calculate the values of the basic parameters of the dynamics. The identified dynamic parameters are used as initial values in the adaptive parameter estimation to obtain the torque, and trajectory scaling is applied to control the contact force between the robot and the environment. Finally, the dynamic parameter identification method and control algorithm are verified by conducting a simulation. The results show that the comprehensive application can help improve the control performance of robots.

An effective approach based on nonlinear spectrum and improved convolution neural network for analog circuit fault diagnosis.

In this work, an effective approach based on a nonlinear output frequency response function (NOFRF) and improved convolution neural network is proposed for analog circuit fault diagnosis. First, the NOFRF spectra, rather than the output of the system, are adopted as the fault information of the analog circuit. Furthermore, to further improve the accuracy and efficiency of analog circuit fault diagnosis, the batch normalization layer and the convolutional block attention module (CBAM) are introduced into the convolution neural network (CNN) to propose a CBAM-CNN, which can automatically extract the fault features from NOFRF spectra, to realize the accurate diagnosis of the analog circuit. The fault diagnosis experiments are carried out on the simulated circuit of Sallen-Key. The results demonstrate that the proposed method can not only improve the accuracy of analog circuit fault diagnosis, but also has strong anti-noise ability.

Fault mechanism analysis and diagnosis for closed-loop drive system of industrial robot based on nonlinear spectrum.

To solve the problem of nonlinear characteristics neglecting and fault mechanism analysis lacking in fault diagnosis research, a new method of fault mechanism analysis and diagnosis based on nonlinear spectrum is proposed. Firstly, based on the Permanent Magnet Synchronous Motor (PMSM) model of robot, the first 4-order spectrums based on nonlinear output frequency response function (NOFRF) in different states are obtained by batch calculation method. Secondly, the high-frequency spectrum distribution rule of NOFRF spectrum in different states are analyzed. Finally, in the closed-loop simulation environment of robot, the identification method based on data-driven is adopted for NOFRF spectrum calculation to verify power loss fault of PMSM. Meanwhile, the fault diagnosis experiment is also carried out. The experimental results indicate that the key characteristics distribution rule of NOFRF spectrums in the real environment is consistent with the theoretical analysis results, and compared with the traditional fault feature extraction methods by output signal, the diagnosis with fault feature of NOFRF spectrum for industrial robot closed-loop drive system has the highest accuracy, which verifies the validity of NOFRF spectrum as the fault feature.

Adaptive variable impedance control of dual-arm robots for slabstone installation.

The conventional dual-arm cooperative control method employed in the construction field cannot adequately meet the requirements of high precision and adaptability because of the use of large objects, heavy load, unstructured environment, and constraints related to the complex operation processes involved. Dual-arm robots are highly complex multi-degree-of-freedom system, and when using this robots for slabstone installation, it is necessary to consider not only the position constraint and force coupling relationship of the closed chain system, but also the force/position control while the slabstone contacts the wall. To solve this problem, this paper presents slabstone-installation model and motion element decomposition for dual-arm robots. Moreover, a control strategy is proposed by combining an adaptive variable impedance tracking controller for the force/position control of the slabstone and a tracking controller for the end-effector trajectories of the dual arms; the controllers proposed meet the requirements of position tracking and contact force tracking of the slabstone. Finally, different slabstone installation scenarios are simulated to verify the effectiveness of the proposed algorithm. The results show that the algorithm is compliant for the slabstone installation process and can meet the requirements of force/position control.

[Corrigendum] Mutation of TGF­ß receptor II facilitates human bladder cancer progression through altered TGF­ß1 signaling pathway.

Subsequently to the publication of the above article, an interested reader drew to the authors' attention that, in Fig. 1B on p. 1552, the MCF­7 and T24, and the A549 and ScaBER data panels, respectively, appeared to be strikingly similar. After having re­examined the original data, the authors have realized that these pairings of data panels were indeed duplicates of each other. Essentially, errors were made in the labelling of the data panels pertaining to the separate experiments, and in the compilation of the published version of Fig. 1. The authors, however, were willing to repeat the affected experiments, and obtained results that were consistent with those of the experiments that had been originally performed. Consequently, the revised version of Fig. 1 is shown below, showing the new data for Fig. 1B. The results from the flow cytometric analysis demonstrated the abnormally high expression level of TGF­ß receptor II in T24 cells. The authors confirm that these data support the main conclusions presented in their paper, and are grateful to the Editor of International Journal of Oncology for allowing them this opportunity to publish a Corrigendum. They also apologise to the readership for any inconvenience caused. [the original article was published in International Journal of Oncology 43: 1549­1559, 2013; DOI: 10.3892/ijo.2013.2065].

The optimized algorithm based on machine learning for inverse kinematics of two painting robots with non-spherical wrist.

This paper studies the inverse kinematics of two non-spherical wrist configurations of painting robot. The simplest analytical solution of orthogonal wrist configuration is deduced in this paper for the first time. For the oblique wrist configuration, there is no analytical solution for the configuration. So it is necessary to solve by general method, which cannot achieve high precision and high speed as analytic solution. Two general methods are optimized in this paper. Firstly, the elimination method is optimized to reduce the solving speed to 20% of the original one, and the completeness of the method is supplemented. Based on the Gauss damped least squares method, a new optimization method is proposed to improve the solving speed. The enhanced step length coefficient is introduced to conduct studies with the machine learning correlation method. It has been proved that, on the basis of ensuring the stability of motion, the number of iterations can be effectively reduced and the average number of iterations can be less than 5 times, which can effectively improve the speed of solution. In the simulation and experimental environment, it is verified.

[Carrier screening for spinal muscular atrophy in 4719 pregnant women in Shanghai region].

OBJECTIVE: Spinal muscular atrophy (SMA) is a common and fatal autosomal recessive disorder. Approximately 94% of SMA patients are caused by homozygous deletion of SMN1 gene. SMA carrier screening is recommended considering the high carrier frequency (1 in 35-50) as well as severity of the disease. METHODS: A prospective population-based cohort study was carried out on 4719 pregnant women from Shanghai region. Copy numbers of SMN1 and SMN2 genes were effectively determined with denaturing high performance liquid chromatography (DHPLC) technique. The method has detected 94% of SMA cases with deletion or conversion of the SMN1 genes. RESULTS: Ninety SMA carriers with only one copy of the SMN1 gene were identified among the 4719 pregnant woman. The carrier rate was 1.9%. Respectively, 1.2% and 0.6% of the carriers were caused by SMN1 gene deletion and SMN1 gene conversion. CONCLUSION: Through this study, we have determined the frequency of SMA mutation carriers in a population of pregnant women. The result may provide a basis for genetic counseling in order to reduce the rate of SMA affected births.

Caprin-1 is a novel microRNA-223 target for regulating the proliferation and invasion of human breast cancer cells.

MicroRNAs (miRNAs) are 21-22 nucleotides regulatory small non-coding RNAs that inhibit gene expression by binding to complementary sequences especially the 3' untranslated region (3'UTR) of mRNA. One miRNA can target many messenger RNAs, leading to a complex metabolic network. Previous studies have shown that miRNA-223 regulates migration and invasion of tumor cells and targets cytoplasmic activation/proliferation-associated protein-1 (Caprin-1). In the present study, we detected the expression of miRNA-223 and Caprin-1 in MCF-7, T-47D and MDA-MB-231 cancer cell lines, and MCF-10A normal breast cell line, and analyzed the role of miRNA-223 in Caprin-1-induced proliferation and invasion of human breast cancer cells. We found that miRNA-223 expression levels are significantly lower in MCF-7, T-47D and MDA-MB-231 cancer cells than in MCF-10A normal breast cells, while Caprin-1 expression is higher in cancer cells than in normal breast cells. The most malignant cancer cell line MDA-MB-231 has the lowest expression of miR-223, but the highest expression of Caprin-1. Further, we found that miR-223 targets the 3'UTR of Caprin-1 miRNA and down-regulates the expression of Caprin-1. We also found that over-expression of Caprin-1 can promote the proliferation and the invasion of breast cancer cells, but miRNA-223 can inhibit the proliferation and the invasion. miRNA-223-induced inhibition can be reversed by ectopic over-expression of Caprin-1. These findings suggest that miR-223 may suppress the proliferation and invasion of cancer cells by directly targeting Caprin-1. Our study also indicates that expression levels of miR-223 and Caprin-1 can be used to predict the state of cancer in breast cancer patient.

Mutation of TGF-ß receptor II facilitates human bladder cancer progression through altered TGF-ß1 signaling pathway.

Tumor cells commonly adapt survival strategies by downregulation or mutational inactivation of TGF-ß receptors thereby reversing TGF-ß1-mediated growth arrest. However, TGF-ß1-triggered signaling also has a protumor effect through promotion of tumor cell migration. The mechanism(s) through which malignant cells reconcile this conflict by avoiding growth arrest, but strengthening migration remains largely unclear. TGF-ßRII was overexpressed in the bladder cancer cell line T24, concomitant with point mutations, especially the Glu269 to Lys mutation (G → A). Whilst leaving Smad2/3 binding unaffected, TGF-ßRII mutations resulted in the unaffected tumor cell growth and also enhanced cell mobility by TGF-ß1 engagement. Such phenomena are perhaps partially explained by the mutated TGF-ßRII pathway deregulating the p15 and Cdc25A genes that are important to cell proliferation and CUTL1 gene relevant to motility. On the other hand, transfecting recombinant TGF-ßRII-Fc vectors or smad2/3 siRNA blocked such abnormal gene expressions. Clinically, such G → A mutations were also found in 18 patients (n=46) with bladder cancer. Comparing the clinical and pathologic characteristics, the pathologic T category (χ2 trend = 7.404, P<0.01) and tumor grade (χ2 trend = 9.127, P<0.01) tended to increase in the G → A mutated group (TGF-ßRII point-mutated group). These findings provide new insights into how TGF-ß1 signaling is tailored during tumorigenesis and new information into the current TGF-ß1-based therapeutic strategies, especially in bladder cancer patient treatment.

Comparison of two functional kappa light-chain transcripts amplified from a hybridoma.

Three heavy-chain and three kappa (κ)-chain transcripts were amplified from hybridoma cells secreting a monoclonal antibody (mAb) against transferrin receptor. Sequence analysis via IMGT/V-QUEST yielded the functional/aberrant prediction. Two functional κ-chain transcripts, Vκ2 and Vκ3, and one functional VH1 were revealed. Comprehensive bioinformatics analyses including sequence alignment, phylogenetic tree, somatic hypermutation prediction, and three-dimensional-molecular structure modeling were used to predict the origin of the two κ-chain transcripts. The results of bioinformatics analysis suggest that Vκ3 is derived from the myeloma partner of the hybridoma; Vκ2 is derived from B-cell. Functional transcripts VH1 and Vκ2 and Vκ3 were then used to construct two chimeric antibodies chi-C2 (Vκ2-VH1) and chi-C3 (Vκ3-VH1), respectively. Antigen-binding experiments showed that only chi-C2 remained the same affinity as its parental mAb. Possible explanations for the coexistence of two functional κ-chain transcripts and the different affinity of the two chimeric antibodies are discussed.

Sinomenine hydrochloride enhancement of the inhibitory effects of anti-transferrin receptor antibody-dependent on the COX-2 pathway in human hepatoma cells.

Transferrin receptor (TfR) has been used as a target for the antibody-based therapy of cancer due to its higher expression in tumors relative to normal tissues. Great potential has been shown by anti-TfR antibodies combined with chemotherapeutic drugs as a possible cancer therapeutic strategy. In our study, we investigated the anti-tumor effects of anti-TfR monoclonal antibody (mAb) alone or in combination with sinomenine hydrochloride in vitro. Results suggested that anti-TfR mAb or sinomenine hydrochloride could induce apoptosis, inhibit proliferation, and affect the cell cycle. A synergistic effect was found in relation to tumor growth inhibition and the induction of apoptosis when anti-TfR mAb and sinomenine hydrochloride were used simultaneously. The expression of COX-2 and VEGF protein in HepG2 cells treated with anti-TfR mAb alone was increased in line with increasing dosage of the agent. In contrast, COX-2 expression was dramatically decreased in HepG2 cells treated with sinomenine hydrochloride alone. Furthermore, we demonstrated that the inhibitory effects of sinomenine hydrochloride and anti-TfR mAb administered in combination were more prominent than when the agents were administered singly. To sum up, these results showed that the combined use of sinomenine hydrochloride and anti-TfR mAb may exert synergistic inhibitory effects on human hepatoma HepG2 cells in a COX-2-dependent manner. This finding provides new insight into how tumor cells overcome the interference of iron intake to survive and forms the basis of a new therapeutic strategy involving the development of anti-TfR mAb combined with sinomenine hydrochloride for liver cancer.

Generation and functional characterization of the anti-transferrin receptor single-chain antibody-GAL4 (TfRscFv-GAL4) fusion protein.

BACKGROUND: The development of vectors for cell-specific gene delivery is a major goal of gene therapeutic strategies. Transferrin receptor (TfR) is an endocytic receptor and identified as tumor relative specific due to its overexpression on most tumor cells or tissues, and TfR binds and intakes of transferrin-iron complex. We have previously generated an anti-TfR single-chain variable fragments of immunoglobulin (scFv) which were cloned from hybridoma cell line producing antibody against TfR linked with a 20 aa-long linker sequence (G4S)4. In the present study, the anti-TfR single-chain antibody (TfRscFv) was fused to DNA-binding domain of the yeast transcription factor GAL4. The recombinant fusion protein, designated as TfRscFv-GAL4, is expected to mediate the entry of DNA-protein complex into targeted tumor cells. RESULTS: Fusion protein TfRscFv-GAL4 was expressed in an E. coli bacterial expression system and was recovered from inclusion bodies with subsequent purification by metal-chelate chromatography. The resulting proteins were predominantly monomeric and, upon refolding, became a soluble biologically active bifunctional protein. In biological assays, the antigen-binding activity of the re-natured protein, TfRscFv-GAL4, was confirmed by specific binding to different cancer cells and tumor tissues. The cell binding rates, as indicated by flow cytometry (FCM) analysis, ranged from 54.11% to 8.23% in seven different human carcinoma cell lines. It showed similar affinity and binding potency as those of parent full-length mouse anti-TfR antibody. The positive binding rates to tumor tissues by tissue microarrays (TMA) assays were 75.32% and 63.25%, but it showed weakly binding with hepatic tissue in 5 cases, and normal tissues such as heart, spleen, adrenal cortex blood vessel and stomach. In addition, the re-natured fusion protein TfRscFv-GAL4 was used in an ELISA with rabbit anti-GAL4 antibody. The GAL4-DNA functional assay through the GAL4 complementary conjugation with the GAL4rec-GFP-pGes plasmid to verify the GLA4 activity and GAL4rec-recognized specificity functions. It also shows the complex, TfRscFv-GAL4-GAL4rec-GFP-pGes, could be taken into endochylema to express the green fluorescent protein (GFP) with 8 to 10-fold transfection efficiency. CONCLUSIONS: Results of our study demonstrated that the biofunctianality of genetically engineered fusion protein, TfRscFv-GAL4, was retained, as the fusion protein could both carry the plasmid of GAL4rec-pGes and bind TfR on tumour cells. This product was able to transfect target cells effectively in an immuno-specific manner, resulting in transient gene expression. This protein that can be applied as an effective therapeutic and diagnostic delivery to the tumor using endogenous membrane transport system with potential widespread utility.

Cell-free DNA in blood is a potential diagnostic biomarker of breast cancer.

Breast cancer is a highly malignant disease in women. A convenient screening tool with high accuracy for early detection, not only in high-risk individuals but in the general population, is necessary. Two hundred breast cancer patients, 100 healthy controls and 100 hyperplasia patients were enrolled in this study. Samples were randomly assigned into training or testing cohorts. The receiver operating characteristic curve was used to explore the optimal concentration of cell-free DNA (GAPDH) in the training cohort and the cut-off point was validated in the testing cohort. The results showed that both in the training and testing cohorts, the overall accuracy of classification between cancer, healthy controls and hyperplasia was higher than 0.9. The sensitivity, specificity, positive predictive value and negative predictive value also reached 0.9, with the exception of the negative predictive value in the testing cohort. This study provides useful information on the use of concentration of free DNA for breast cancer detection. These findings need to be validated in a large prospective trial prior to clinical application.