We report on the yield of Polyhedral Inclusion Bodies (PIBs) from first to fifth instar Helicoverpa armigera larvae inoculated with wild-type Helicoverpa armigera nucleopolyhedrovirus (HaSNPV-WT) or ...with one of two HaSNPV recombinants, one in which the ecdysteroid UDP-glucosyltransferase (egt) gene was deleted (HaSNPV-EGTD) and a second in which the egt gene was replaced by a scorpion toxin (AaIT) gene (HaSNPV-AaIT). A significant linear relationship between the logarithm of cadaver weight and the logarithm of the number of PIBs per cadaver was observed for all three virus types. The increase of the number of PIBs with larval weight was significantly greater for HaSNPV-WT than for the recombinant viruses. For each of the three HaSNPVs, PIB yield per cadaver was significantly affected by larval instar at death and by time to death, with later instars and longer surviving larvae producing a greater number of PIBs. As both recombinants caused host larvae to die at earlier instars than HaSNPV-WT, their virus yields were significantly reduced. Virus yield per larva, inoculated with HaSNPV-AaIT in the first, second, third, fourth or fifth larval stage was 23, 32, 41, 44 and 47% of the yield of HaSNPV-WT, respectively. For HaSNPV-EGTD, virus yield per larva inoculated in first through fifth instar, respectively, was 41, 55, 63, 54 and 82% of the yield of HaSNPV-WT. These results provide a basis for optimizing the production regime of recombinant HaSNPVs in larvae and for modeling the behavior of these viruses in agro-ecosystems
Cotton bollworm (Helicoverpa armigera) is a serious pest on cotton in China. A specific baculovirus, H. armigera nucleopolyhedroviruses (HaSNPV) is used as a commercial biopesticide to control this ...pest. To improve the pesticidal properties, HaSNPV has been genetically engineered by both deleting the ecdysteroid UDP-glucosyltransferase (egt) gene from its genome (recombinant HaSNPV-EGTD) and incorporating an insect-selective toxin gene from the scorpion Androctonus australis (AaIT) (recombinant HaSNPV-AaIT). In the field, there was no significant difference among the inactivation rates of the two recombinant HaSNPVs and their parent wild-type, HaSNPV-WT. The inactivation rate of these viruses was significantly different in different years. The average half-life of HaSNPV was 0.57, 0.90 and 0.39 days in 2000, 2001 and 2002, respectively. Inactivation rates correlated well with solar radiation over these years.
As a novel representation method, two dimensional (2D) segmentation is gaining ground as an effective condition monitoring method due to its high-level information descriptional ability. However, the ...accuracy of extracting frequency information is still limited by the finite gray-level and the extraction ability of distinguishable texture for each fault. To overcome these drawbacks, this research proposes a bearing fault diagnosis method using the converted 2D vibrational signal matrices. In this method, 1D vibration signals are converted into 2D matrices to exploit the fault signatures from the converted images. Curvature filtering (mean curvature) algorithm is applied to eliminate the overwhelming interfering contents and preserves the necessary edge information contained in the 2D matrix. In addition, the histogram of oriented gradients features is employed for the effective fault feature extraction. Finally, a one-versus-one support vector machine is utilized for the automatically fault classification. An experimental investigation was carried out for the performance evaluation of the proposed method. Comparison results indicate that the established method is capable of bearing fault detection with considerable accuracy.
The orientation information is critical for the mobile robot. However, the robot's constrained locomotion, complicated magnetic field environment, and the coupled orientation estimation present ...challenges for using the microelectromechanical magnetometer in real-time robot orientation determination. This article focuses on calibrating the magnetometer in constrained robot locomotion and achieving the robot's decoupled roll, pitch, and yaw estimates. A magnitude-free and reference-free calibration approach is proposed to calibrate the magnetometer using the measurements collected from the principal plane of the robot locomotion. Moreover, a decoupled orientation estimator is created under the framework of the extended Kalman filter using the calibrated triaxial magnetic, angular rate, and gravity sensor readings. Two independent experiments validate the effectiveness of magnetometer calibration and orientation decoupling, respectively. A case study of estimating the mobile robot's orientation shows that the proposed methods can achieve accurate heading estimation and decouple the roll and pitch from the magnetic field data.
As a typical example of large and complex mechanical systems, rotating machinery is prone to diversified sorts of mechanical faults. Among these faults, one of the prominent causes of malfunction is ...generated in gear transmission chains. Although they can be collected via vibration signals, the fault signatures are always submerged in overwhelming interfering contents. Therefore, identifying the critical fault's characteristic signal is far from an easy task. In order to improve the recognition accuracy of a fault's characteristic signal, a novel intelligent fault diagnosis method is presented. In this method, a dual-tree complex wavelet transform (DTCWT) is employed to acquire the multiscale signal's features. In addition, a convolutional neural network (CNN) approach is utilized to automatically recognise a fault feature from the multiscale signal features. The experiment results of the recognition for gear faults show the feasibility and effectiveness of the proposed method, especially in the gear's weak fault features.
Accurate orientation estimation using low-cost inertial and magnetic sensors is important. However, since the magnetometer measurements affect pitch and roll estimates in addition to yaw ...determination, the resultant accuracy reduction under magnetic disturbances is adverse for special occasions where high-precision pitch and roll estimates are essential. This article presents a double-extended Kalman filter (DEKF) orientation estimator with unit quaternion as output, which decouples magnetometer effects on pitch and roll estimates by decomposing the orientation into tilt quaternion and heading quaternion. The tilt quaternion, including pitch and roll information, is estimated by the first EKF where accelerometer and gyroscope measurements are processed and the inaccurate heading information is discarded. The heading quaternion, solely describing the yaw orientation, is determined by the second EKF, which fuses the vertical component of angular rate measurements and the horizontal component of magnetic measurements. True quaternion is denoted by the multiplicative of tilt and heading quaternions. The separate property of DEKF limits the influences of magnetic disturbances on yaw estimation, making the pitch and roll angles immune to them. Experiment results show that the proposed method solves the coupled disturbance problem without losing accuracy.
Abstract The biodegradable silk-based scaffold with unique mechanical property and biocompatibility represents a favorable ligamentous graft for tissue-engineering anterior cruciate ligament (ACL) ...reconstruction. However, the low efficiency of ligament-bone interface restoration barriers the isotropic silk graft to common ACL therapeutics. To enhance the regeneration of the silk-mediated interface, we developed a specialized stratification approach implementing a sequential modification on isotropic silk to constitute a triphasic silk-based graft in which three regions respectively referring to ligament, cartilage and bone layers of interface were divided, followed by respective biomaterial coating. Furthermore, three types of cells including bone marrow mesenchymal stem cells (BMSCs), chondrocytes and osteoblasts were respectively seeded on the ligament, cartilage and bone region of the triphasic silk graft, and the cell/scaffold complex was rolled up as a multilayered graft mimicking the stratified structure of native ligament-bone interface. In vitro , the trilineage cells loaded on the triphasic silk scaffold revealed a high proliferative capacity as well as enhanced differentiation ability into their corresponding cell lineage. 24 weeks postoperatively after the construct was implanted to repair the ACL defect in rabbit model, the silk-based ligamentous graft exhibited the enhancement of osseointegration detected by a robust pullout force and formation of three-layered structure along with conspicuously corresponding matrix deposition via micro-CT and histological analysis. These findings potentially broaden the application of silk-based ligamentous graft for ACL reconstruction and further large animal study.
The tumour stroma is an active participant during cancer progression. Stromal cells promote tumour progression and metastasis through multiple mechanisms including enhancing tumour invasiveness and ...angiogenesis, and suppressing immune surveillance. We report here that miR-126/miR-126(*), a microRNA pair derived from a single precursor, independently suppress the sequential recruitment of mesenchymal stem cells and inflammatory monocytes into the tumour stroma to inhibit lung metastasis by breast tumour cells in a mouse xenograft model. miR-126/miR-126(*) directly inhibit stromal cell-derived factor-1 alpha (SDF-1α) expression, and indirectly suppress the expression of chemokine (C-C motif) ligand 2 (Ccl2) by cancer cells in an SDF-1α-dependent manner. miR-126/miR-126(*) expression is downregulated in cancer cells by promoter methylation of their host gene Egfl7. These findings determine how this microRNA pair alters the composition of the primary tumour microenvironment to favour breast cancer metastasis, and demonstrate a correlation between miR-126/126(*) downregulation and poor metastasis-free survival of breast cancer patients.
In the last decades, aqueous zinc-ions batteries (AZIBs) have attained enormous attention owing to their environmental friendliness, the abundant resources of Zn and the safety of aqueous ...electrolytes. However, the sluggish zinc-ions diffusion rate results in poor electrochemical properties. Therefore, seeking an appropriate cathode material is a brilliant method to deal with this problem. In this work, the heterostructure of Zn3V3O8 and ZnO encapsulating into 3D interpenetrating carbon network (Zn3V3O8@ZnO@NC) is prepared to serve as cathode material for AZIBs. Benefiting from the structural stability of the cross-stacked structure and outstanding electrochemical conductivity of the 3D interpenetrating carbon network, the electrode material delivers remarkable cyclic stability (120.5 mA h g−1 at 5 A g−1 after 2000 cycles). The discharge capacity only reduces 33.3 mAh g−1 with the current density increase from 0.5 A g−1 to 3 A g−1 (216.3 mA h g−1 and 183 mA h g−1 at 0.5 A g−1 and 3 A g−1, respectively), revealing a super-stable rate performance. Besides, the zinc ion storage mechanism of Zn3V3O8@ZnO@NC was revealed via ex-situ XRD and XPS characterizations. The results reveal that Zn3V3O8@ZnO@NC was transformed into Zn3(OH)2V2O7·2H2O (ZOVO) during the first charge process between 1.2 and 1.4 V and the transformation is completed after the two cycles. After the second cycle, the Zn2+ storage is provided only by the de(intercalation) of Zn2+ in ZOVO.
•Zn3V3O8@ZnO@NC heterostructure was prepared through assembling nanodisks into cross-stacked architecture.•Zn3V3O8@ZnO@NC heterostructure presents excellent rate capacity and cycle stability.•3D interpenetrating and carbon wrapping nanodisks frameworks improve electronic conductivity and structure stability.•Ex-situ XRD and XPS results further demonstrate the super Zn2+ storage.
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