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Highly homogeneous magnetic fields in magnetic resonance spectrometers are an important guarantee for improving the quality of spectra for chemical structure analysis and kinetic information. The active shimming process using a shimming power supply to drive a shimming coil to produce a compensating electromagnetic field is an essential way to improve the homogeneity of the magnetic field. The high accuracy and stability of the shimming power supply’s output are crucial indicators for improving the active shimming capability and maintaining the shimming results. The paper develops a high-precision, high-stability, low-ripple active shimming power supply system for magnetic resonance spectrometers, and designs a shimming current driver (constant current source) with output state monitoring based on negative feedback control, coupled with an MCU control platform and host computer system to complete the closed-loop transmission of control commands and data between hardware and software, to achieve digital constant current output control. Under R=2.84 Ω, L=25.5 µH shimming coil load, the full-scale output response time is less than 18.9 µs, the output ripple peak-to-peak control is 30 mV, the positive and negative current output symmetry is good, and the maximum output deviation is 4.8‰ for long time operation. This power supply was used in a nuclear magnetic resonance spectrometer system using 0.5 T-Halbach configuration magnets, and the magnetic field homogeneity was optimised from 24.48 ppm (10-6) to 2.72 ppm by driving a first-order shimming coil. This work contributes to the integration of compact nuclear magnetic resonance spectrometer systems and the applications related to active shimming.

Temperature drift is an important factor affecting the measurement accuracy of desktop NMR spectrometers, and adding a field-locking coil to the probe to achieve field-frequency interlocking is a common means of suppressing temperature drift. In this paper, a dual-channel miniaturised RF probe with an external field-locking channel is designed based on a laboratory compact Halbach magnet. The coil diameter, height, number of turns, turn spacing and enamelled wire radius were optimized based on the solenoid structure. The optimum solenoid size was obtained with an enameled wire radius of 0.4 mm, a coil diameter and height of 8.2 mm, a turn spacing of 1.6 mm and a number of turns of 5. Based on the simulation results, the detection and field-locking coils were fabricated, and tested in conjunction with the peripheral circuitry. The results show that the crosstalk between the two coils is low, the signal-to-noise ratio of the detection channel is above 50 and the signal-to-noise ratio of the locking channel is above 20. Final field locking experiments were performed and the frequency drift of the overall system after equipping the locking field was approximately 0.2 ppm/h (1 ppm=10-6), verifying that this probe design can be applied in compact Halbach magnet-based NMR analysis facilities.

Objectives This study is focused on improving the performance and increasing the detection probability of a multiple Unmanned Underwater Vehicle （UUV） seabed acoustic beacon searching a specific sea area.Methods First, the search ability index function of the passive sonar is given. Second, the Monte Carlo method is used to randomly simulate the coordinate position of the submarine acoustic beacon. Third, the cluster search capability function is established and the optimization goal of the optimization task is obtained. The optimization constraints are established in combination with the formation requirements of the UUV actually performing the task. Finally, the integration is based on the seabed acoustic beacon search probability. The cluster formation optimization model is maximized and the UUV cluster is made to complete the acoustic beacon search work in the specified area according to this formation. In this paper, the genetic algorithm is used to optimize the parameters of the optimization model. By setting a reasonable objective function and improving the traditional genetic operator, the value of the objective function reaches the set standard. At this point, the corresponding parameters are taken out to complete the value selection.Results By comparing this new optimized formation with the traditional optimized formation, it is found that the optimized formation has a higher average probability of finding the submarine beacon.Conclusions The optimized model test results show that the proposed method can effectively improve the submarine acoustic beacon search performance of UUV clusters and provide a reasonable formation optimization scheme.

Two methods for measuring pulse wave using either a pressure or an optical sensor are studied and compared. A model for determining the optimal external force for restraining the pressure sensor is proposed. Pulse waves are measured on 20 volunteers. The restraint force on the pressure sensor is slowly varied and recorded using a piezoelectric film sensor for each person until it reaches a so-called optimal acquisition pressure under which the pulse wave has the greatest amplitude. The optimal pressure is then analyzed using polynomial regression with the body-mass index(BMI). In addition, the pulse waves are decomposed in both the time and frequency domains to identify and extract the features corresponding to physiological activities. Pulse waves measured with the optical sensor method suffer from feature point loss where certain points are submerged and indistinguishable. The pressure sensor method can reveal the feature points clearly, but the waveform exhibits variations if the external force applied isn′t a constant. With the application of optimal acquisition force set by our model, the latter method is able to detect pulse wave with a high signal-to-noise ratio. The dual domain analysis is shown to extract features that can be later used for continuous blood pressure monitoring.

Compared with the inert metal (gold), the active metal (Cd) is much more prone to oxidation, leading to its high oxidation state. In this work, we found that doping the homogold [Au.sub.25] [(SR).sub.18] nanocluster with cadmium largely enhances its stability. The differential pulse voltammetry (DPV) analysis suggested that Cd doping raised the high occupied molecular orbital (HOMO) energy of homogold [Au.sub.25] nanocluster, which led to stronger retention of its valence electrons. [Cd.sub.1][Au.sub.24][(SR).sub.18] nanocluster also exhibited much higher activity than homogold [Au.sub.25] nanocluster in aerobic benzyl alcohol oxidation. Keywords Metal cluster * Doping * Synergistic effect * Aerobic oxidation catalysis * Oxidation * Differential pulse voltammetry, Introduction Gold nanoclusters (NCs) with a few tens of metal atoms have emerged as a new class of nanomaterials with wide application [1-5]. By doping these small homogold nanoclusters with [...]

To investigate the prognostic value of tumor deposits (TDs) counts in stage III colorectal cancer (CRC) patients and develop a prognostic nomogram. Data on stage III CRC patients from 2010 to 2015 were collected from the Surveillance, Epidemiology, and End Results (SEER) database. The Kaplan–Meier analysis was used to assess differences in survival outcomes among patients. The Cox regression analysis was performed to establish the independent prognostic factors for cancer-specific survival and to establish a nomogram. The nomograms' performance was evaluated by calibration plots and concordance index (C-index). Decision curve analysis (DCA) was used to assess the clinical utility of the prediction model. A total of 23,345 CRC patients were included in this study, and 3,578 (15.3%) had TDs. Cox multivariate regression analyses revealed that age, race, histological tumor grade, the administered chemotherapy, pathological type, T-stage, CEA, N-stage, peripheral nerve invasion, and TDs were independent prognostic factors. Patients with many TDs (=0/1–4, HR: 1.325,/≥5 HR: 2.223) had poorer cancer-specific survival. The prognostic value of the number of TDs was comparable to that of lymph node metastasis. The C-indices of the nomogram were superior to TNM staging in training (0.730 vs 0.646) and validation (0.714 vs 0.636) groups. DCA revealed that the nomogram had a higher clinical net benefit compared to TNM staging. TDs count is an adverse prognostic factor for stage III CRC patients. Furthermore, the TDs-based nomogram can accurately predict the prognostic outcomes for stage III CRC. [ABSTRACT FROM AUTHOR]

This paper implements the parameter identification of ship roll motion based on vibration tests and the computational fluid dynamics (CFD) method. By applying sinusoidal moment excitations from a shaker, we successfully simulate the quasi-roll motion behavior of the ship model in the air. We conduct two vibration tests, including a constant-amplitude angular displacement test and a constant-amplitude angular velocity test, to identify the restoring moment and the damping moment coefficients of the quasi-roll motion. In addition, we perform the approximate equivalence of the fluid around the ship through the CFD method and the fluid-solid coupling technique. Thus, we obtain the hydrodynamic coefficients, such as the added mass moment of inertia and the equivalent damping, to accomplish the parameter identification of the ship's real roll motion. Finally, the accuracy of the identified parameters is verified by means of numerical simulations based on the Runge–Kutta method. [ABSTRACT FROM AUTHOR]

N6‐methyladenosine (m6A) has emerged as the most prevalent post‐transcriptional modification on mRNA that contributes prominently to tumorigenesis. However, the specific function of m6A methyltransferase methyltransferase‐like 3 (METTL3) in colorectal cancer (CRC) remains elusive. Herein, we explored the biological function of METTL3 in CRC progression. Clinically, METTL3 was frequently upregulated in CRC tissues, cell lines, and plasma samples and its high expression predicted poor prognosis of CRC patients. Functionally, knockdown of METTL3 significantly repressed CRC cell proliferation and migration in vitro, while its overexpression accelerated CRC tumor formation and metastasis both in vitro and in vivo. Mechanistically, METTL3 epigenetically repressed YPEL5 in an m6A‐YTHDF2‐dependent manner by targeting the m6A site in the coding sequence region of the YPEL5 transcript. Moreover, overexpression of YPEL5 significantly reduced CCNB1 and PCNA expression. Collectively, we identified the pivotal role of METTL3‐catalyzed m6A modification in CRC tumorigenesis, wherein it facilitates CRC tumor growth and metastasis through suppressing YPEL5 expression in an m6A‐YTHDF2‐dependent manner, suggesting a promising strategy for the diagnosis and therapy of CRC. [ABSTRACT FROM AUTHOR]

Urban agriculture(UA) is a spontaneous response to the increasing demand for food with the inevitable population expansion in urban areas. As a critical part of FAO’s Special Programme for Food Security(SPFS), UA has increasingly been considered as a significant contributor to food and nutrition security of urban residents all over the world. Thus, the central aim of this essay is to develop a better understanding of the current situation of UA in urban planning of China, and 6 categories of UA in China will be discussed, including Leisure Agriculture, Modern Agricultural Science and Technology Park, Community Supported Agriculture(CSA), Institutional garden and Edible landscape. And finally the paper tries to raise the awareness and drive innovation of UA in both theory and practice. [ABSTRACT FROM AUTHOR]