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Objective: Osteosarcoma is a malignant bone tumor consisting of mesenchymal cells. This study aimed to investigate the inhibitory effects of human bone marrow mesenchymal stem cell (hBMSC)-derived miR-1913 on osteosarcoma. Methods: Cell viability was determined using CCK8 and colony formation assays. The cell migration and invasion abilities were assessed using wound healing and transwell assays. RT-qPCR and western blot were used to measure the miR-1913, Neurensin-2 (NRSN2), N-cadherin, and E-cadherin expression levels. Dual luciferase reporter assays were conducted to identify the target relationship between miR-1913 and NRSN2. The exosomes were extracted and identified using TEM and NTA assays. Results: In the osteosarcoma tumor tissues and cell lines, the NRSN2 expressions were up-regulated, which correlated with a poor osteosarcoma prognosis. MiR-1913 inhibited the cell viability, proliferation, migration, and invasion by negatively targeting NRSN2. Furthermore, the hBMSC-derived exosomes delivered miR-1913 to inhibit the NRSN2 expression in the osteosarcoma cells. Conclusion: The inhibitory role of hBMSC-derived miR-1913 on osteosarcoma progression was achieved by targeting NRSN2, indicating the potential therapeutic value of hBMSC-derived miR-1913.

Background and aims Coronavirus disease 2019 (COVID-19) is a new infectious disease. To reveal the hepatic injury related to this disease and its clinical significance, we conducted a multicenter retrospective cohort study that included 5,771 adult patients with COVID-19 pneumonia in Hubei Province. Approach and results We reported the distributional and temporal patterns of liver injury indicators in these patients and determined their associated factors and death risk. Longitudinal liver function tests were retrospectively analyzed and correlated with the risk factors and death. Liver injury dynamic patterns differed in alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bilirubin (TBIL). AST elevated first, followed by ALT, in severe patients. ALP modestly increased during hospitalization and largely remained in the normal range. The fluctuation in TBIL levels was mild in the non-severe and the severe groups. AST abnormality was associated with the highest mortality risk compared with the other indicators of liver injury during hospitalization. Common factors associated with elevated liver injury indicators were lymphocyte count decrease, neutrophil count increase, and male gender. Conclusion The dynamic patterns of liver injury indicators and their potential risk factors may provide an important explanation for the COVID-19-associated liver injury. Because elevated liver injury indicators, particularly AST, are strongly associated with the mortality risk, our study indicates that these parameters should be monitored during hospitalization.

To assess the value of combined chromosomal karyotyping and chromosomal microarray analysis (CMA) for prenatal diagnosis.G-banding karyotyping and CMA were simultaneously performed on 546 women who were subjected to amniocentesis during middle pregnancy.In total 82 cases were detected with chromosomal abnormalities. The two methods were consistent in 43 cases, which included 14 trisomy 21, 6 trisomy 18, 1 trisomy 13, 14 sex chromosomal aneuploidies, 4 chromosomal deletions, 3 chromosomal duplications and 1 sex chromosomal mosaicism. Fifteen fetuses with chromosomal abnormalities detected by CMA were missed by karyotyping analysis, which included 9 microdeletions and 6 microduplications. Sixteen fetuses with chromosomal abnormalities detected by karyotyping analysis were missed by CMA, which included 15 chromosomal translocations and 1 sex chromosomal mosaicism. In 7 cases, the results of karyotyping analysis and CMA were inconsistent. One supernumerary marker chromosome detected by karyotyping analysis was verified by CMA as 9p13.1p21.1 duplication.Combined chromosomal karyotyping and CMA can significantly improve the detection rate for chromosomal abnormalities, which has a great value for prenatal diagnosis.

The wire and arc additive manufacturing (WAAM) method based on an indirect arc between two non-consumable tungsten electrodes in confined space has been proposed and preliminarily investigated, which is applicable in vacuum or sub-atmosphere ambient conditions. Visual inspection results showed that the stable burning arc kept continuously melting the metallic wire. Because there is no current flowing through the droplets and molten pool, the important process feature of low heat input was revealed. A cubic boron nitride (CBN) ceramic nozzle is used to force the arc and to produce droplets pass through it for additional constriction and trajectory regulation. The constricted-shielding gas and arc plasma offer fine protection and additional heating for the melted droplets during the whole process. The arc length increased as the gas flow rate rose from 4 L/min to 10 L/min. The arc shapes became dispersed when the gas flow rate exceeded 10 L/min. The arc shapes and droplets transfer process can be improved by the ceramic nozzle. Both of the forming characteristics and metallurgical bonding strength can be dramatically improved. The geometrical dimensions of each layer can be effectively regulated through adjusting wire feed and depositing speed.

Wire arc additive manufacturing (WAAM) has unmatched efficiency and cost advantages in the formation of large-scale structural parts while the forming accuracy and forming quality deteriorate due to the increase of heat accumulation during the forming process. The authors have proposed a variant technology called compulsively constricted WAAM (CC-WAAM) trying to solve the problem of excessive heat input. The present study focuses on the physical generating process of arc and droplets in the confined space during CC-WAAM using high speed photography. The results revealed that arc behaviors and droplets transfer were very unstable at low-level electrical parameters with the feature that the droplets transfer diameters were large (1.8–5.3 mm), the droplets transfer frequencies were low (2–23 Hz), and the arc phenomena were complicated. While the opposite phenomena were obtained at high-level electrical parameters, achieving a droplet of 0.8 mm and a transfer frequency 300 Hz. Further experiments were conducted to study the influences of the shielding gas flow on arc behaviors and droplets transfer. The gas made arc disperse at low-level electrical parameters and promoted the arc plump at high-level electrical parameters. Preliminary force analysis of the droplets was made to explain the droplets transfer trajectories. And optimized parameters setup has been obtained to produce stable arc burning and predictable small-size droplet transfer.

TACC3, a member of the transforming acidic coiled-coil protein (TACC) family, is a multifunctional protein that is involved in various biological functions, including proliferation and differentiation of tumor cells, cancer progression and metastasis. The aims of the present study were to examine whether TACC3 expression is associated with the proliferation and migration of osteosarcoma (OS) cells and to investigate the potential underlying molecular mechanisms of TACC3 in OS. First, the levels of mRNA and protein expression in OS cell lines by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively were examined. Second, the effects of TACC3 knockdown and overexpression on the proliferative, migratory and invasive capacities of OS cells were investigated. Finally, western blot analysis was employed to detect the potential mechanism of TACC3 in osteosarcoma. TACC3 expression was significantly increased in osteosarcoma tissues and cell lines, compared to matched controls. The knockdown of TACC3 was able to significantly inhibit the proliferation, migration and invasion of osteosarcoma cells, whereas the overexpression of TACC3 was able to promote cell proliferation and migration. Mechanistically, TACC3 may promote the migration and invasion of osteosarcoma cells via through nuclear factor-κB signaling. These data suggest that TACC3 has an important part in the progression of osteosarcoma and may serve as a potential target for gene therapy.

Wire ropes have been widely used in elevators, lifting machinery, passenger aerial ropeways, and other related fields. Such ropes often deteriorate during their lifetime due to external or internal corrosion and abrasion, and dynamic mechanical stresses. Nondestructive evaluation methods are being increasingly applied to monitor wire ropes. In this paper, an adjustable, annular testing device, consisting of probes arranged in radial symmetry, is designed using low frequency transmission eddy current testing. The testing device is designed to overcome the usual limitations of eddy current techniques, namely the lift-off effect, edge effect, and skin effect. Peak-to-peak difference and phase difference of the response signal to the excitation signal are used as signal features, and are extracted using a numerical algorithm. A radial basis function neural network (NN) is proposed for the identification of broken wires within a wire rope. The NN models are established by offline training, with three different rope types and signal features being NN inputs, and number of wire-breaks being the output. The experimental eddy current sensor and computer measuring system has been developed to obtain characteristic data for rope samples made in our laboratory. The characteristic data are indentified by the RBF network, and the identification results show the proposed evaluation method to test if wire ropes is feasible and practical.

In regenerative medicine, accumulating evidence demonstrates that the property of substrates monitors neural stem cells behavior. However, how stem cells sense and interpret biochemical and topographical cues remains elusive. This study aimed to explore the mechanism how nanofibrous scaffold modulated stem cells behavior. Spinal cord derived neural progenitor cells (NPCs) were cultured on electrospun aligned and randomly oriented collagen nanofibrous scaffolds. A 30% increase in proliferation and an elevation of BrdU incorporation were observed in NPCs on collagen nanofibers, compared to that on collagen-coated surface. In particular, NPCs expanded faster on aligned nanofibers in comparison with that on randomly oriented nanofibers. Moreover, an alteration in cell cycle progression with a reduced percentage of cells in G0/G1 phase and increased cell proliferation index (S phase plus G2/M phase) was also detected in NPCs cultured on collagen nanofibers. Incubating NPCs with anti-β1 integrin antibody or U1026 (an inhibitor of mitogen-activated protein kinase kinase, MEK) eliminated the altered cell cycle dynamics and BrdU incorporation induced by collagen nanofibers. In addition, cyclin D1 and cyclin dependent kinase 2 (CDK2), downstream genes of β1 integrin/mitogen-activated protein kinase (MAPK) pathway that control G1/S phase transition, were correspondingly regulated by nanofibers. Collectively, these data suggested that the property of substrate modulated NPCs proliferation by promoting cell cycle through β1 integrin/MAPK pathway. Our findings provide a better understanding of the interaction between NPCs and the substrate and therefore will pave way for regenerative medicine.

Ideal tissue-engineered scaffold materials regulate proliferation, apoptosis and differentiation of cells seeded on them by regulating gene expression. In this study, aligned and randomly oriented collagen nanofiber scaffolds were prepared using electronic spinning technology. Their diameters and appearance reached the standards of tissue-engineered nanometer scaffolds. The nanofiber scaffolds were characterized by a high swelling ratio, high porosity and good mechanical properties. The proliferation of spinal cord-derived neural stem cells on novel nanofiber scaffolds was obviously enhanced. The proportions of cells in the S and G2/M phases noticeably increased. Moreover, the proliferation rate of neural stem cells on the aligned collagen nanofiber scaffolds was high. The expression levels of cyclin D1 and cyclin-dependent kinase 2 were increased. Bcl-2 expression was significantly increased, but Bax and caspase-3 gene expressions were obviously decreased. There was no significant difference in the differentiation of neural stem cells into neurons on aligned and randomly oriented collagen nanofiber scaffolds. These results indicate that novel nanofiber scaffolds could promote the proliferation of spinal cord-derived neural stem cells and inhibit apoptosis without inducing differentiation. Nanofiber scaffolds regulate apoptosis and proliferation in neural stem cells by altering gene expression.

Precision of positioning and operation are enormously affected by vibration while flexible manipulator is running. Great attention has been paid on the research on vibration control of flexible manipulator. However, there is shortage of effective and uniform real-time simulation platform to date. Based on the study of coupled modeling and dynamic characteristics, the two-link flexible manipulator system made of piezoelectric smart structure was established. The manipulator's motion was controlled by single-chip computer system and serial communication module provided by simulink. The date exchange between manipulator system and the MATLAB workspace was implemented by the data acquisition module, which combined physical system with virtual environment. So the real-time simulation system for vibration control of flexible manipulator was set up. Adopted the PID control algorithm, the entire experimental system was debugged. The results showed that the system can work normally, and the PID control algorithm can also effectively suppress the vibration of flexible manipulator. The platform can be used for vibration control experimental research and the actual system.

Motion controller is one of the core components in construction machinery equipment. Compared with general-purpose motion controller based on PC or PLC, embedded motion controller (EMC) for construction machinery is characterized by the strong pertinency and specialty for this field. This paper describes the key technologies on developing the hardware and software of EMC for construction machinery, including architecture of embedded hardware and software platform, drive protection and current feedback of PWM, power supply technology, fault diagnosis and tolerance, standard of IEC61131-3 for control configuration etc. Two research & development modes and the current technology status of EMC in the world are analyzed. An example of developing EMC product is presented. Furthermore, the development trend to high-end, intellectualization and informatization of EMC for construction machinery and its optimization impact on operating mode of the product are discussed. A great opportunity for developing the brands of EMC is also pointed out.

Mobile computing is characterized by limited resources on mobile client, frequent disconnection and limited bandwidth of mobile communication, and the heterogeneity between different mobile database products. Aimed at the defects existed in current technologies of synchronizing replication for mobile databases, a new model of transaction synchronization and replication is proposed. The conflict processing strategy is emphatically analyzed and the implementation algorithm is presented in detail. The conflict preprocessing mechanism based on user-concerned data and transaction-related-set is adopted and executed before conflict detection and resolution in the model, which effectively saves the storage resources on mobile client and mobile communication bandwidth, reduces the workloads and error possibility of mobile server, decreases the complexity of the conflict detection and resolution algorithm. The conflict reconciliation strategy based on rule simplifies conflict processing and enhances the efficiency of synchronization and replication. In addition, the implementation method of the model using SyncML protocol has the generality and adaptability for different types of major heterogeneous database products.

With the ever-increasing application of embedded systems in the field of industrial control, the demand for embedded configuration software becomes inevitable. This paper presents a general method of developing embedded configuration software based on embedded Linux operation system. The software architecture consisting of host and target is given out. The relationship between graphic-element classes and its implementation are described. The animation implementation technology of dynamic graphic-elements and data communication mechanism based on signal and slot are discussed in detail. Furthermore, aimed at the poor processing power of embedded microprocessors and the limited storage resources on embedded platforms, the paper proposes a multi-level strategy for the performance optimization of embedded configuration software. The experiment result shows that this embedded configuration software can meet userpsilas requirements on real-time performance and resource consumption, and thus has application prospect and popularization value.