A SE-DenseNet-LSTM model for locomotion mode recognition in lower limb exoskeleton.

Locomotion mode recognition in humans is fundamental for flexible control in wearable-powered exoskeleton robots. This article proposes a hybrid model that combines a dense convolutional network (DenseNet) and long short-term memory (LSTM) with a channel attention mechanism (SENet) for locomotion mode recognition. DenseNet can automatically extract deep-level features from data, while LSTM effectively captures long-dependent information in time series. To evaluate the validity of the hybrid model, inertial measurement units (IMUs) and pressure sensors were used to obtain motion data from 15 subjects. Five locomotion modes were tested for the hybrid model, such as level ground walking, stair ascending, stair descending, ramp ascending, and ramp descending. Furthermore, the data features of the ramp were inconspicuous, leading to large recognition errors. To address this challenge, the SENet module was incorporated, which improved recognition rates to some extent. The proposed model automatically extracted the features and achieved an average recognition rate of 97.93%. Compared with known algorithms, the proposed model has substantial recognition results and robustness. This work holds promising potential for applications such as limb support and weight bearing.

Study on Linewidth and Phase Noise Characteristics of a Narrow Linewidth External Cavity Diode Laser.

In the field of inter-satellite laser communication, achieving high-quality communication and compensating for the Doppler frequency shift caused by relative motion necessitate lasers with narrow linewidths, low phase noise, and the ability to achieve mode-hop-free tuning within a specific range. To this end, this paper investigates a novel external cavity diode laser (ECDL) with a frequency-selective F-P etalon structure, leveraging the external cavity F-P etalon structure in conjunction with an auxiliary filter to achieve single longitudinal mode selection. The laser undergoes linewidth testing using a delayed self-heterodyne beating method, followed by the testing of its phase noise and frequency noise characteristics using a noise analyzer, yielding beat spectra and noise power spectral density profiles. Furthermore, the paper introduces an innovative bidirectional temperature-scanning laser method to achieve optimal laser-operating point selection and mode-hop-free tuning. The experimental results showcase that the single longitudinal mode spectral side-mode suppression ratio (SMSR) is around 70 dB, and the output power exceeds 10 mW. Enhancing the precision of the F-P etalon leads to a more pronounced suppression of low-frequency phase noise, reducing the Lorentzian linewidth from the initial 10 kHz level to a remarkable 5 kHz level. The bidirectional temperature-scanning laser method not only allows for the selection of the optimal operating point but also enables mode-hop-free tuning within 160 pm.

Anomaly Detection Method for Lithium-Ion Battery Cells Based on Time Series Decomposition and Improved Manhattan Distance Algorithm.

Abnormalities in individual lithium-ion batteries can cause the entire battery pack to fail, thereby the operation of electric vehicles is affected and safety accidents even occur in severe cases. Therefore, timely and accurate detection of abnormal monomers can prevent safety accidents and reduce property losses. In this paper, a battery cell anomaly detection method is proposed based on time series decomposition and an improved Manhattan distance algorithm for actual operating data of electric vehicles. First, time series decomposition is performed on the voltage data of all battery cells in the battery pack to obtain the voltage trend component of each cell. Then, the improved Manhattan distance algorithm is utilized to calculate and compare the Manhattan distance values between adjacent cell trend components, to determine the abnormal cells inside the battery pack. Furthermore, the Manhattan distance values at the same sampling moment are calculated within the data sequence to detect the specific time when the abnormal cells malfunction. The data analysis and experimental verification results based on actual vehicle operating conditions indicate that this method can accurately identify an abnormal cell within the battery pack and diagnose the specific moment of abnormality in the battery cell at an early stage of failure, with good robustness.

[Analysis of the clinical effect of percutaneous pedicle screw fixation combined with transpedicular bone grafting in the treatment of thoracolumbar fracture].

OBJECTIVE: To investigate the clinical efficacy of percutaneous screw fixation combined with minimally invasive transpedicular bone grafting and non-bone grafting in the treatment of thoracolumbar fractures. METHODS: From Janury 2021 to June 2022, 40 patients with thoracolumbar fracture were divided into the experimental group and the control group. There were 26 patients in the experimental group, including 21 males and 5 females with an aberage age of (47.3±12.3) years old, who underwent percutaneous pedicle screw fixation combined with transpedicular autogenous bone grafting. In the control group, 14 patients received percutaneous pedicle screw fixation only. including 7 makes and 7 females with an average age of (50.2±11.2) years old. The operative time, intraoperative blood loss, anterior height ratio of injured vertebrae, Cobb angle, visual analogue score (VAS), MacNab scores, loosening or broken of the implants. were compared and analyzed. RESULTS: There was no significant difference in operation time, intraoperative blood loss, VAS and anterior height ratio of injured vertebrae between the two groups. Compared with the preoperative results, VAS and anterior height ratio of injured vertebrae were improved statistically(P<0.05). For Cobb angle of injured vertebra, there was no significant difference between the two groups before surgery (P=0.766). While at 1 week, 3 months and 12 months after surgery, there were statistically differences between the two groups (P values were 0.042, 0.007 and 0.039, respectively). The Cobb angle of injured vertebrae one year after operation was statistically decreased in both groups compared with that before surgery (P<0.001). One year after surgery, the excellent and good rate of Macnab scores was 96.15% in the experimental group and 92.86% in the control group, and there was no statistical differences between the two groups (P=0.648). There was one patient in the control group suffering superficial wound infection on the third day, which was cured by dressing change and anti-infection treatment. There were no postoperative screw loosening and broken in both groups. CONCLUSION: The two surgical methods have the advantages of less trauma, less pain and quicker recovery, which can restore the height of the injured vertebra, reconstruct the spinal sequence and reduce the fracture of the vertebral body. Transpedicular autogenous bone grafting can increase the stability of the fractured vertebra and maintain the height of the vertebra better after surgery, thus reducing the possibility of complications such as kyphosis, screw loosening and broken.

Development of a single LMS loop three channels analog adaptive co-site interference cancelling system.

Co-site interference is becoming prominent on some independent platforms (e.g., airplanes, satellites, space stations, and vessels). Although many digital multichannel cancellation algorithms have been investigated, the saturation problem of the receiver front-end caused by severe co-site interference should be addressed first with analog RF cancellation. Many studies are currently being conducted to develop an analog adaptive co-site interference cancellation system (AACICS). However, double LMS (Least Mean Square) loop in every channel raises the complexity and implemented difficulty. Above all, the interference cancellation in the scene of antenna swaying has received little attention, which severely limits the effective suppression of wideband interference. This study developed an analog 3-channel adaptive co-site wideband interference cancellation system (AACWICS-3ch) with one LMS loop in every channel and established the equivalent model of the AACWICS-3ch. The steady-state weight and interference cancellation ratio (ICR) were obtained by analyzing and solving the equivalent model. An in-depth analysis was conducted on the quantitative relationship correlations between the interference cancellation bandwidth, ICR, system gain, and antenna swing amplitude. Results reveal that AACWICS-3ch can greatly enhance the interference cancellation performance compared to 2-channel analog adaptive co-site interference cancellation system (AACICS-2ch). The maximum improved ICR is greater than 30 dB, and it overcomes the complexity of double LMS loop cancellation system with the increasing of channel. Finally, simulations and experiments validated the improvement of interference cancellation performance in AACWICS-3ch.

Detection of railway catenary insulator defects based on improved YOLOv5s.

In this article, a method of railway catenary insulator defects detection is proposed, named RCID-YOLOv5s. In order to improve the network's ability to detect defects in railway catenary insulators, a small object detection layer is introduced into the network model. Moreover, the Triplet Attention (TA) module is introduced into the network model, which pays more attention to the information on the defective parts of the railway catenary insulator. Furthermore, the pruning operations are performed on the network model to reduce the computational complexity. Finally, by comparing with the original YOLOv5s model, experiment results show that the average precision (AP) of the proposed RCID-YOLOv5s is highest at 98.0%, which can be used to detect defects in railway catenary insulators accurately.

Fault Diagnosis Method for Lithium-Ion Battery Packs in Real-World Electric Vehicles Based on K-Means and the Fréchet Algorithm.

Battery failure has traditionally been a major concern for electric vehicle (EV) safety, and early fault diagnosis will reduce many EV safety accidents. However, the short-circuit signal is generally very weak, so it is still a challenge to achieve a timely warning of battery failure. In this paper, an initial microfault diagnosis method is proposed for the data of electric vehicles in actual operation. First, a robust locally weighted regression data smoothing method is proposed that can effectively remove noisy data and retain fault characteristics. Second, an ordinary-least-squares-based voltage potential feature extraction method is proposed, which can effectively capture the small fault features of battery cells and achieve early warning. Third, a reference cell selection method based on K-means clustering is proposed, which can effectively reduce the false alarms caused by the inconsistency of each cell. Fourth, the Fréchet algorithm is introduced into the field of battery pack fault diagnosis and combined with thresholds for battery pack fault diagnosis and localization to accomplish the diagnosis and early warning of minor faults. Finally, the fault diagnosis method is validated by three actual running electric vehicles to verify the effectiveness, reliability, and robustness of the method.

A Biocatalytic Platform for the Synthesis of Enantiopure Propargylic Alcohols and Amines.

Propargylic alcohols and amines are versatile building blocks in organic synthesis. We demonstrate a straightforward enzymatic cascade to synthesize enantiomerically pure propargylic alcohols and amines from readily available racemic starting materials. In the first step, the peroxygenase from Agrocybe aegerita converted the racemic propargylic alcohols into the corresponding ketones, which then were converted into the enantiomerically pure alcohols using the (R)-selective alcohol dehydrogenase from Lactobacillus kefir or the (S)-selective alcohol dehydrogenase from Thermoanaerobacter brokii. Moreover, an enzymatic Mitsunobu-type conversion of the racemic alcohols into enantiomerically enriched propargylic amines using (R)-selective amine transaminase from Aspergillus terreus or (S)-selective amine transaminase from Chromobacterium violaceum was established. The one-pot two-step cascade reaction yielded a broad range of enantioenriched alcohol and amine products in 70-99% yield.

Adipose Stem Cell-Derived Exosomes Recover Impaired Matrix Metabolism of Torn Human Rotator Cuff Tendons by Maintaining Tissue Homeostasis.

BACKGROUND: Adipose stem cell-derived exosomes (ASC-Exos) are reported to effectively prevent muscle atrophy and degeneration of torn rat rotator cuff, but their influence on human samples and their potential mechanism are still unclear. PURPOSE: We aimed to investigate the effects of ASC-Exos on the metabolic activities of torn human rotator cuff tendons and explore the potential mechanism behind it. STUDY DESIGN: Controlled laboratory study. METHODS: Diseased supraspinatus tendons were harvested from 15 patients with a mean ± SD age of 65.8 ± 3.2 years who underwent reverse shoulder arthroplasty for chronic rotator cuff tears associated with glenohumeral pathological changes. Each tendon was dissected into 3 × 4 × 4-mm explants: the ones derived from the same tendon were placed into 12-well plates and cultured in complete culture media (control) or in complete culture media supplemented with ASC-Exos for 72 hours. Afterward, the concentrations of cytokines secreted into the culture media-including interleukin 1ß (IL-1ß), IL-6, IL-8, and matrix metalloproteinase 9 (MMP-9)-were measured using enzyme-linked immunosorbent assay (ELISA). Tendons were stained with hematoxylin and eosin and immunohistochemistry (type I and III collagens) for histological analyses. Moreover, the expression of anabolic genes (TIMP-1 and TIMP-3; type I and III collagen encoding) and catabolic genes (MMP-9 and MMP-13) in tendons were measured using real-time quantitative polymerase chain reaction. Phosphorylated AMPKα and Wnt/ß-catenin pathways were assayed by western blotting to explore the potential mechanism of action of ASC-Exos. RESULTS: Secretion of proinflammatory cytokines, including IL-1ß, IL-6, and MMP-9, was significantly reduced in the ASC-Exos group as compared with the control group. Supraspinatus tendons in the ASC-Exos group exhibited superior histological properties, as demonstrated by higher tendon maturing scores and more type I collagen content, but there was no significant difference in type III collagen content between groups. Expression of MMP-9 and MMP-13 genes was decreased in the ASC-Exos group versus the control group. Increased expression of type I and III collagens and an elevated type I/III ratio were found in the ASC-Exos group when compared with the control group. There was no significant difference in the secretion of IL-8 and expression of TIMP-1 and TIMP-3 genes between the ASC-Exos and control groups. Western blotting revealed that ASC-Exos enhanced phosphorylated AMPKα and decreased ß-catenin levels to prevent tendon degeneration. CONCLUSION: ASC-Exos maintained metabolic homeostasis of torn human rotator cuff tendons to improve their histological properties, which might be achieved by enhancing AMPK signaling to suppress Wnt/ß-catenin activity. CLINICAL RELEVANCE: ASC-Exos could be used as an effective biological tool to promote healing in torn human rotator cuff tendons.

Shadow Elimination Algorithm Using Color and Texture Features.

Shadow detection and removal in real scene images are a significant problem for target detection. This work proposes an improved shadow detection and removal algorithm for urban video surveillance. First, the foreground is detected by background subtraction and the shadow is detected by HSV color space. Using local variance and OTSU method, we obtain the moving targets with texture features. According to the characteristics of shadow in HSV space and texture feature, the shadow is detected and removed to eliminate the shadow interference for the subsequent processing of moving targets. Finally, we embed our algorithm into C/S framework based on the HTML5 web socket protocol. Both the experimental and actual operation results show that the proposed algorithm is efficient and robust in target detection and shadow detection and removal under different scenes.

Video Foreground Detection Algorithm Based on Fast Principal Component Pursuit and Motion Saliency.

Aiming at the shortcoming of being unsuitable for dynamic background and high computational complexity of the existing RPCA- (robust principal component analysis-) based block-sparse moving object detection method, this paper proposes a two-stage foreground detection framework based on motion saliency for video sequence. At the first stage, the observed image sequence is regarded as the sum of a low-rank background matrix and a sparse outlier matrix, and then the decomposition is solved by the RPCA method via fast PCP (principal component pursuit). At the second stage, the sparse foreground blocks are obtained according to the spectral residuals and the spatial correlation of the foreground region. Finally, the block-sparse RPCA algorithm through fast PCP is used to estimate foreground areas dynamically and to reconstruct the foreground objects. Extensive experiments demonstrate that our method can exclude the interference of background motion and change, simultaneously improving the detection rate of small targets.

Transition-metal-free amination phosphoryl azide for the synthesis of phosphoramidates.

A facile and efficient approach to phosphoramidates was developed via amination of phosphoryl azides. A variety of phosphoramidates were obtained in one step with good to excellent yields under a mild reaction system. The process uses easily available amines as a N source and offers a new opportunity for P-N bond formation.

Fe-catalyzed esterification of amides via C-N bond activation.

An efficient Fe-catalyzed esterification of primary, secondary, and tertiary amides with various alcohols for the preparation of esters was performed. The esterification process was accomplished with FeCl3·6H2O, which is a stable, inexpensive, environmentally friendly catalyst with high functional group tolerance.

Design, Synthesis and In Vitro Anti-microbial Evaluation of Ethylene/ Propylene-1H-1,2,3-Triazole-4-Methylene-tethered Isatin-coumarin Hybrids.

OBJECTIVE: A new class of ethylene/propylene-1H-1,2,3-triazole-4-methylene-tethered isatincoumarin hybrids 8a-j, integrating three anti-tuberculosis pharmacophores coumarin, isatin and 1,2,3- triazole was designed and synthesized. METHOD: These hybrids were assessed for their in vitro anti-TB activity against MTB H37Rv and MDRTB, as well as anti-bacterial activity against Gram-positive and Gram-negative strains, and cytotoxicity in VERO cell line. RESULTS: The results showed that all hybrids with acceptable cytotoxicity (CC50: 64-512 µg/mL) exhibited weak to moderate anti-microbial activity. The most active hybrid 8i with MIC of 50 µg/mL against MTB H37Rv and MDR-TB, also has excellent cytotoxicity profile (CC50: 128 µg/mL). CONCLUSION: The resistance index of hybrid 8i was 1, indicating that hybrid 8i has no cross-resistance with the first-line anti-TB agent. Thus, hybrid 8i could act as a lead for further optimization.

Synthesis of tricyclic quinazolinones via intramolecular cyclization of 3-(2-aminoalkyl)-2-(phenylamino)quinazolin-4(3H)-ones.

Bioactive tricyclic quinazolines class of 3,4-dihydro-1H-pyrimido[2,1-b]quinazolin-6(2H)-ones I and 2,3-dihydroimidazo[2,1-b]quinazolin-5(1H)-ones II were synthesized by the formic acid-catalyzed intramolecular cyclization of 3-(2-aminoalkyl)-2-(phenylamino)quinazolin-4(3H)-ones 1 in high yields. A plausible mechanism of the cyclization step is proposed.

Synthesis and biological activity of arylsulfonamide derivatives containing 2-arylamino-4(3H)-quinazolinone.

Twenty arylsulfonamide derivatives containing 2-arylamino-4(3H)-quinazolinone were synthesized and evaluated for their bioactivities. 4-Fluoro-N-(2-(4-oxo-2-(4-(trifluoromethoxy)phenyl)amino)quinazolin-3(4H)-yl)ethyl benzenesulfonamide, showed excellent activity both against Ralstonia solanacearum and Gibberella zeae with the inhibition rates of 100% (200 mg/L) and 95% (100 mg/L), and 69% (50 mg/L), respectively, exceeding that of the assigned commercial bactericide (thiodiazole-copper) and fungicide (hymexazol). The preliminary structure activity relationships (SAR) showed that both benzene rings of arylamino and arylsulfonamido moieties containing electron-withdrawing substitutes may be preferable for improving the bioactivity of target compounds.

[An Improved Cubic Spline Interpolation Method for Removing Electrocardiogram Baseline Drift].

The selection of fiducial points has an important effect on electrocardiogram(ECG)denoise with cubic spline interpolation.An improved cubic spline interpolation algorithm for suppressing ECG baseline drift is presented in this paper.Firstly the first order derivative of original ECG signal is calculated,and the maximum and minimum points of each beat are obtained,which are treated as the position of fiducial points.And then the original ECG is fed into a high pass filter with 1.5Hz cutoff frequency.The difference between the original and the filtered ECG at the fiducial points is taken as the amplitude of the fiducial points.Then cubic spline interpolation curve fitting is used to the fiducial points,and the fitting curve is the baseline drift curve.For the two simulated case test,the correlation coefficients between the fitting curve by the presented algorithm and the simulated curve were increased by 0.242and0.13 compared with that from traditional cubic spline interpolation algorithm.And for the case of clinical baseline drift data,the average correlation coefficient from the presented algorithm achieved 0.972.

An enantioselective cascade reaction between α,ß-unsaturated aldehydes and malonic half-thioesters: a rapid access to chiral δ-lactones.

We disclose a novel efficient enantioselective organocatalytic cascade reaction for the preparation of δ-lactones in good to excellent yields (69-93%) and with high to excellent enantioselectivities (88-96% ee).

5,5'-Seleno-bis-(2-hy-droxy-benzaldehyde).

In the title mol-ecule, C(14)H(10)O(4)Se, the dihedral angle between the two benzene rings is 74.6 (1)°. Both hy-droxy-benzaldehyde groups form intra-molecular O-H⋯O hydrogen bonds. In the crystal, pairs of mol-ecules are linked by pairs of weak C-H⋯π(arene) inter-actions, forming centrosymmetric dimers. In addition, mol-ecules are linked by π-π stacking inter-actions, with a centroid-centroid distance of 3.785 (2) Å, forming chains along the c axis.