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This is an essay in the field of mineral analysis. In recent years, Chinese geological researchers have discovered a new type of sedimentary rare earth ore in Yunnan and Guizhou regions, which is not only different from bastnaesite and monazite, but also different from ionic rare earth ore in south of China, but a unique rare earth ore in clay rocks. In this paper, the ore dissolution methods of two rare earth samples with different grade from different mineral sites in adjacent areas of Yunnan and Guizhou are compared, and the distribution of key rare earth elements（Pr、Nd、Tb、Dy）, the optimization of instrument parameters and the accuracy and precision of the determination method of key rare earth elements are studied in detail. The results show that the closed digestion system is the best method for the new deposit of rare earth ore, and ICP-MS is an accurate and efficient determination method with good precision and accuracy.

This is an essay in the field of mineral analysis. The ore sample was digested with Hydrochloric acid、nitric acid、 hydrofluoric acid、 sulfuric acid in a closed polytetrafluoroethylene digestion tank. Hydrochloric acid and tartaric acid medium is used for extraction. The Lithium、Beryllium、niobium and tantalum in the prepared solution were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The emission spectral intensity of Lithium、Beryllium、niobium and tantalum showed a good linear relationship with ρ(Li) and ρ(Be) in the range of 0~50 μg/mL、ρ(Nb2O5) and ρ(Ta2O5) in the range of 0~100 μg/mL. The correlation coefficients of the calibration curve for Lithium、Beryllium、niobium and tantalum were both 0.9999．The detection limits for Lithium、Beryllium、niobium and tantalum were 0.1 μg/g、0.5 μg/g、1.0 μg/g、0.1 μg/g, respectively．The proposed method was applied to the determination of the actual sample giving recovery rate of 94.6%~105.6% and the relative standard deviations (RSD n=11) of Lithium、Beryllium、niobium and tantalum are 1.08%~7.04%、0.65%~13.06%、2.59~7.32%、2.02%~7.60%, respectively．This method was applied to the analysis of the standard sample and the results were consistent with the certified values．

The rotor magnetic shunt structure hybrid excitation synchronous motor (RMS-HESM) has been widely used in marine propulsion due to its advantages of low loss and high efficiency. The objective of this paper is to improve the output torque capability of the hybrid excitation motor with a rotor magnetic shunt structure by conducting a multi-objective optimization design for the magnetic permeability structure. The first step involved establishing a mathematical analytical model of average torque and torque ripple based on the fundamental principle of motor magnetization. Next, the parameters of the magnetic permeability structure were designed and analyzed using the finite element simulation method. The impact of the variations in the parameters of the magnetic permeability structure on motor torque and no−load back electromotive force was examined. Additionally, a sensitivity analysis was performed on the design variables of the magnetic permeability structure, leading to the determination of optimization parameters based on the obtained results. The adaptive inertia weight-based particle swarm algorithm (PSO) was employed to conduct a multi-objective optimization design analysis. A comparative analysis on the average torque, torque ripple, and no−load back electromotive force of the motor before and after optimization was performed using the Maxwell and Workbench and Optislong joint simulation tools. This enhancement significantly improves the torque performance of the marine motor while simultaneously optimizing the no−load back electromotive force.

To explore the influence of the excitation current in the rotor magnetic shunt hybrid excitation synchronous motor (HESM) on the vibration and noise of the motor, the finite element analysis of the hybrid excitation motor was carried out by using ANSYS Workbench software and noise sources for analysis. Firstly, air-gap flux density at different excitation currents and density vector diagrams are studied. Secondly, radial electromagnetic force’s order and frequency characteristics under different excitation currents are discussed. Finally, the modal analysis of the stator of the motor is carried out. The motor’s vibration response and noise variation under different excitation current conditions are summarized. The simulation analysis and experimental verify that the motor’s vibration response and noise increase obviously when the excitation current is significant, and the vibration acceleration of different orders increases.

To suppress the switching dead-band in the Open-End Winding Permanent Magnet Synchronous Machine with Common DC bus (OW-PMSM-CDCB) drive system, the dual-inverter switch dead-band generates zero-sequence voltage and current during 120°decoupling modulation. The generation mechanism of dead-band voltage is analyzed with the help of Matlab/Simulink and a method to compensate for the zero-sequence voltage resulting from the dead-band of dual-inverter switches is discussed in this study. With the help of current polarity detection, the zero-sequence voltage resulting from the dead-band of the switch is offset by solving the dead-band voltage compensation amount, and an OW-PMSM-CDCB drive system experimental platform is built for experimental verification. Simulation and experimental show that the proposed compensation method can effectively suppress the zero-sequence current of OW-PMSM-CDCB.

To solve the problem of high harmonic in the stator current of Permanent-Magnet Synchronous Motor (PMSM), a current harmonic suppression method combining Three-parameter Notch Filter (TNF) and Linear Active Disturbance Rejection Controller (LADRC) is proposed. First, the current loop controller adopts LADRC, and Linear extended state observer (LESO) is used to estimate the disturbance signal. The harmonic suppression performance is studied in the frequency domain. Second, the TNF is used to extract and feedforward compensation the harmonic signals of a specific frequency, which further weakens the influence of medium and low-frequency current harmonics on the performance of the motor. Finally, the simulation and experimental results verify that the proposed strategy can obviously reduce the distortion degree of the current, and improve the steady-state performance of PMSM.

In order to research vibration and noise of TMPS-HESM. The Magnetic pole eccentricity TMPS-HESM is established. The order and frequency characteristics of radial electromagnetic force are discussed The vibration and noise coupling model is built by ANSYS Workbench simulation platform. The vibration response and noise variation are discussed. The results show that magnetic pole eccentricity can effectively reduce air gap flux density harmonic content, and third harmonic is significantly decreased. The excitation current will significantly affect the harmonic (8,2f1), (16,4f1), (0,12f1) components of radial electromagnetic force of magnetic pole eccentricity TMPS-HESM. Although the (0,12f1) component is not the same order of magnitude as other components, it will still worsen the vibration noise of the motor.

In the electric spring (ES) topology, traditional smart load (SL) consists of non-critical loads (NCL) and ES in series to regulate power and stabilize the voltage of critical load (CL). Aiming at the problem that NCL cannot always obtain stable voltages, this paper derives the circuit diagram of ES and CL in series to form new SL to stabilize voltage of NCL through circuit transformation. The new SL combines with the traditional SL to form switchable SL. The circuit topology of switchable SL is deduced, and the basic principle of switchable SL is analyzed. The control strategy of ES with switchable SL is studied. The simulation experiment results in Matlab/Simulink show that the voltage of different loads can be stabilized by controlling ES with switchable SL in different time periods.

Interior Permanent Magnet Synchronous Motor (IPMSM) significantly speed fluctuations under load change suddenly conditions. With the help of MATLAB/Simulink simulation software, a novel IPMSM speed loop control strategy is studied. A Fuzzy linear active disturbance rejection (Fuzzy-LADRC) speed controller is designed, and the LADRC parameters are dynamically adjusted by Fuzzy control to reduce the speed fluctuations of IPMSM in this paper. Finally, the dSPACE experimental platform is used to conduct simulations and experiments. The simulation and experimental results show that the Fuzzy-LADRC has stronger anti-disturbance than the conventional LADRC controlled IPMSM drive system, and the motor speed fluctuations are small.

With the help of instantaneous power theory and Matlab/Simulink simulation tools, the principle of electrical spring (ES) steady-state operation modes division was analyzed, the instantaneous power changes of ES in different steady-state operation modes were studied, then the equivalence circuit of ES under different operating conditions were deduced, the problem that how the steady-state operation mode of ES switches to stabilizes the critical load voltage with the different working conditions was analyzed. Simulation experiments verify the correctness of the research results.

Although many prior studies have found that landscape pattern significantly affects urban heat environment globally, the spatially heterogeneous in the cooling effects of landscape pattern remains poorly understood. In addition, most previous studies have only employed a single landscape metric separately, without holistic consideration of the composition and configuration of different landscapes. Taking one of the new “stove” cities in China-Fuzhou City, Fujian Province, as an example, we employed the principal component analysis (PCA) to synthesize a landscape pattern comprehensive index (LPCI) composed of the four common landscape metrics (i.e., aggregation index, AI; mean patch area, Area mn; largest patch index, LPI; and percentage of landscape, PLAND) of the three major land surfaces (i.e., water, vegetation, and impervious surface). Then, the local model (geographically weighted regression, GWR) was proposed to explore the spatially heterogeneous in the cooling effects of urban landscape. The results revealed that: (1) from 2000 to 2016, the land surface temperature (LST) increased by 4.262 °C, and the proportion of the urban heat island region showed an upward trend, while the urban-heat-island ratio index (URI) increased from 0.328 to 0.457; (2) the cooling effect of different land surfaces ranked from high to low was: water (29.69 °C), vegetation (38.56 °C), and impervious surface (41.82 °C); (3) compared with vegetation patches, water patches had a more obvious cooling effect on the surrounding environment, with the cooling distance within 60–90 m for the vegetation, while reaching 120–150 m for water body; (4) the proposed LPCI could explain more than 80% of the information for all of the landscape metrics for all of the landscape types, and presented a patchy distribution in the study area; (5) the GWR results revealed that the cooling effect of the landscape pattern varied spatially across the study area, indicating that the configuration of landscapes is more important in an urban center in alleviating urban heat environment than in an urban fringe area. The proposed approach provides a new understanding of the interaction between the landscape patterns and urban heat environments, providing a strong basis for landscape planning strategies for specific local sites.

Abstract Bromodomain and extraterminal domain (BET) family proteins are considered to be epigenetic readers that regulate gene expression by recognizing acetyl lysine residues on histones and nonhistone chromatin factors and have been classified as curative targets for a variety of cancers. Glioma‐initiating cells (GICs), which commit self‐renewal, perpetual proliferation, multidirectional differentiation, and vigorous tumorigenicity, sustain the peculiar genetic and epigenetic diversification in the GBM patients, thus, GICs result in tumor recurrence. Abundant evidence demonstrates that BET proteins regulate differentiation of stem cells. However, it endures ambiguous how individual BET proteins take part in GIC advancement, and how do small molecule inhibitors like I‐BET151 target functional autonomous BET proteins. Here, we validated that BRD4, not BRD2 or BRD3, has value in targeted glioma therapy. We announce a signaling pathway concerning BRD4 and Notch1 that sustains the self‐renewal of GICs. Moreover, in‐depth mechanistic research showed that BRD4 was concentrated at the promoter region of Notch1 and may be involved in the process of tumor metabolism. Furthermore, in intracranial models, I‐BET151 eliminated U87 GICs’ tumorigenicity. The outcomes of this research could be conducive to design clinical trials for treatment of glioma based on BRD4.

This study was to develop a feasible and safe animal model for minimally invasive injectable lumbar interbody fusion using a novel biomaterial, mineralized collagen-polymethylmethacrylate bone cement (MC-PMMA), with unilateral pedicle screw fixation in an in vivo goat model. Eight goats ( Capra aegagrus hircus ) were divided into three groups: MC-PMMA, unmodified commercial-polymethylmethacrylate bone cement (UC-PMMA), and a control group (titanium cage filled with autogenous bone, TC-AB). Each group of goats was treated with minimally invasive lumbar interbody fusion at the L3/L4 and L5/L6 disc spaces (injected for MC-PMMA and UC-PMMA, implanted for TC-AB). The pedicle screws were inserted at the L3, L4, L5, and L6 vertebrae, respectively, and fixed on the left side. The characteristics of osteogenesis and bone growth were assessed at the third and the sixth month, respectively. The methods of evaluation included the survival of each animal, X-ray imaging, and 256-layer spiral computed tomography (256-CT) scanning, imaged with three-dimensional microfocus computed tomography (micro-CT), and histological analysis. The results showed that PMMA bone cement can be extruded smoothly after doping MC, the MC-PMMA integrates better with bone than the UC-PMMA, and all goats recovered after surgery without nerve damage. After 3 and 6 months, the implants were stable. New trabecular bone was observed in the TC-AB group. In the UC-PMMA group a thick fibrous capsule had formed around the implants. The MC-PMMA was observed to have perfect osteogenesis and bone ingrowth to adjacent bone surface. Minimally invasive injectable lumbar interbody fusion using MC-PMMA bone cement was shown to have profound clinical value, and the MC-PMMA showed potential application prospects.

Background: An outbreak of SARS-CoV-2 infections began in Wuhan, China, and quickly spread to the entire country. We sought to delineate the time features of clinical symptoms, virological conversion, and chest radiological abnormalities in individuals infected with this virus in Zhuhai, China.Methods: In this retrospective study, we assessed 85 confirmed cases of COVID-19 in the Fifth Hospital of Sun Yat-sen University, Zhuhai, from the 17th of January to the 11th of February 2020. Outcomes were followed up until the 24th of February 2020.Results: The median age of the 85 patients with COVID-19 was 43 years (range, 1–80); 56.5% (48/85) were female. The median time from the last known contact to the first SARS-CoV-2 positive test result was 8 days (0–18). The time to throat swab negativity for SARS-CoV-2 ranged from 5 to 36 days after illness onset. Patients with abnormal chest imaging findings on admission were older than those with normal imaging findings (median age, 50 [3-80] vs. 37 [1-69], P = 0.031). Among patients with lung changes on admission, the risk of lesions was 13.8 times greater in the left lower lobe than in the right middle lobe. Most lung lesions appeared within 2 weeks of onset (median 4–5 days). The overall rates of lesions in the right upper/middle/lower lobe and left upper/lower lobe were 47.1, 30.6, 62.4% as well as 49.4 and 63.5%, respectively.Conclusions: The incubation period of SARS-CoV-2 may be longer than 14 days; thus, medical surveillance after contact is required for longer than this. The predominant sites of lung lesions are both lower lungs, whereas the lowest risk region is the right middle lobe.

Following intraparenchymal injection of the dopamine (DA) neurotoxin 6-hydroxydopamine, we previously demonstrated passage of fluoresceinisothiocyanate-labeled albumin (FITC-LA) from blood into the substantia nigra (SN) and striatum suggesting damage to the blood–brain barrier (BBB). The factors contributing to the BBB leakage could have included neuroinflammation, loss of DA neuron control of barrier function, or a combination of both. In order to determine which factor(s) was responsible, we assessed BBB integrity using the FITC-LA technique in wild-type (WT), tumor necrosis factor alpha (TNF-α) knockout (KO), and minocycline (an inhibitor of microglia activation) treated mice 72 h following treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Compared with WT mice, TNF-α KO mice treated with MPTP showed reduced FITC-LA leakage, decreased numbers of activated microglia, and reduced proinflammatory cytokines (TNF-α and interleukin 1β) associated with significant MPTP-induced DA neuron loss. In contrast, minocycline treated animals did not exhibit significant MPTP-induced DA neuron loss although their FITC-LA leakage, numbers of activated microglia, and MPTP-induced cytokines were markedly attenuated. Since both TNF-α KO and minocycline treatment attenuated MPTP-induced BBB dysfunction, microglial activation, and cytokine increases, but had differential effects on DA neuron loss, it appears that neuroinflammation and not DA neuron loss was responsible for disrupting the blood–brain barrier integrity.

The vibration and noise of a low-speed high-torque permanent magnet motor with a dovetail magnetic isolation device (DMID) structure is analyzed. The motor structure and the main structural parameters of the DMID are introduced, and the radial electromagnetic force wave of the motor is investigated. The notch width, radius, and position of the inner circle of the DMID are selected as design variables, and the constraint conditions are given. The influence of a single parameter on the radial electromagnetic force wave is discussed. The multi-objective optimization of the particle swarm optimization (PSO) algorithm is used to obtain the Pareto relatively optimal solution set that simultaneously satisfies the requirements of low noise, ample output torque, and small torque ripple, and the optimal design scheme is selected. Besides, the harmonic amplitudes of the radial electromagnetic force, motor vibration acceleration, electromagnetic noise, losses, and efficiency are compared and analyzed before and after optimization. Finally, the electromagnetic vibration experiment of a permanent magnet synchronous motor is carried out, and the data shows the feasibility of the above analysis. The results show that the optimal design scheme of the structure parameters of DMID can increase the average output torque, reduce the torque ripple, and effectively reduce the electromagnetic vibration and noise of the motor. [ABSTRACT FROM AUTHOR]

Introduction: Staphylococcus aureus was associated with more than 1 million deaths in 2019. The coronavirus disease 2019 (COVID-19) pandemic has lasted three years. In China, measures to control COVID-19 cases were adjusted in December 2022. In this study, we investigated the effects of the COVID-19 pandemic on the drug resistance of S. aureus infection. Aim: Understanding the impact of the adjustment of COVID-19 control measures on the drug sensitivity of S. aureus will provide a reference for empirical drug use and the prevention of clinical S. aureus infection. Methods: A retrospective analysis was performed, focusing on the clinical distribution and drug resistance of distributions of S. aureus isolated from the Fifth Affiliated Hospital of Sun Yat-sen University during the COVID-19 pandemic from January 2020 to March 2023. The effects of COVID-19 control measures on the drug resistance of S. aureus infection were further investigated. Results: A total of 1,437 strains of S. aureus were isolated, with a methicillin-resistant S. aureus detection rate of 19.2%. The department with the highest detection rate was the oncology department (17.0%, 244/1,437), followed by the intensive care unit (11.1%, 159/1,437), the dermatology department (10.7%, 154/1,437), and the wound repair and burn department (9.7%, 139/1,437). The most frequent specimens were secretions (42.0%, 603/1,437), followed by sputum (23.3%, 335/1,437), blood (10.7%, 154/1,437), and pus (5.4%, 78/1,437). The population distribution was primarily male (62.3%, 895/1,437). S. aureus infections were most common among those aged 50-65 (32.8%, 472/1,437), followed by those aged 18-49 (30.7%, 441/1,437). Staphylococcus aureus was most resistant to penicillin G (86.3%), followed by erythromycin (37.9%) and clindamycin (37.3%). The antibiotics with no resistance were linezolid, teicoplanin, tigecycline, and vancomycin. There was no significant difference in the drug-resistance rate between COVID-19-positive and COVID-19-negative patients. Conclusion: The outbreak of COVID-19 in 2020 and the adjustment of control measures had no significant impact on the drug resistance of S. aureus infection. [ABSTRACT FROM AUTHOR]