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1.
Dig Dis Sci ; 2024 Apr 09.
Article in English | MEDLINE | ID: mdl-38594433

ABSTRACT

BACKGROUND: When unintentional pancreatic duct access occurs during difficult biliary cannulation, the double guidewire (DGW) or transpancreatic sphincterotomy (TPS) may be utilized. DGW can be easily switched to TPS due to the existing guidewire in the pancreatic duct. However, the efficacy of TPS after DGW, named sequential DGW-TPS technique, versus primary TPS has not been assessed. AIMS: Our aim was to compare the benefits and adverse events of sequential DGW-TPS technique and primary TPS. METHODS: We performed a comparative retrospective cohort study that enrolled a total of 117 patients with native papillae. The patients were divided into one of 2 groups according to the primary bile duct access technique (sequential DGW-TPS or primary TPS), both with pancreatic stenting. RESULTS: Between November 2017 and May 2023, a total of 84 patients were grouped into sequential DGW-TPS and 33 into primary TPS. The overall post-ERCP pancreatitis (PEP) rate was 4.3% in the entire cohort, with no statistical differences were observed between the groups in terms of PEP rates (P = 0.927), PEP severity (P = 1.000), first biliary cannulation success (P = 0.621), overall cannulation success (P = 1.000), hyperamylasemia incidence (P = 0.241), elevated amylase levels (P = 0.881), and postoperative hospital stay (P = 0.185). Furthermore, these results remained consistent in multivariable regression analysis. CONCLUSIONS: The sequential DGW-TPS technique showed a comparable safety and biliary cannulation success rate to primary TPS in difficult biliary cannulation. Given the potential long-term complications associated with TPS, DGW should be first if inadvertent pancreatic access occurs, with TPS serving as second only if DGW fails.

2.
Rev Sci Instrum ; 94(12)2023 Dec 01.
Article in English | MEDLINE | ID: mdl-38117201

ABSTRACT

In this paper, a kind of tightly coupled array (TCA) with time-domain beam scan is developed for the radiation of high-power ultrawideband (UWB) electromagnetic pulses, and the peak-power pattern is proposed to characterize the directivity. First, the active voltage standing wave ratio (AVSWR) bandwidth of the TCA is optimized, which is the precondition for the beam scan. It indicates that the lower-cutoff frequency (LCF) is inversely proportional to the total length of the whole array; an increase in the distance between the array and the ground plane could remarkably reduce the LCF; and an increase in the element number can also decrease the LCF because of the increase in length, but more elements would make the center elements difficult to match in the low-frequency range, so there is a limitation on the number of elements for a certain LCF. Based on these results, a six-element linear array is designed. Then, the definition of the peak-power pattern is proposed to characterize the directivity of the UWB pulsed antenna. Finally, the optimized six-element array is developed, and the measured working band is 276 MHz-6.4 GHz (AVSWR < 3). The effective potential gain is 1.76, and it improves by 51.7% with a reduction in the aperture area by 68.4% compared with the previous TCA, which means that the aperture efficiency is remarkably improved. The half-power beam width of the developed TCA with the scan angle of 0° is 45°. The time-domain beam scan could be performed with time-delay feeding lines, and the maximum scan angle is over ±30° in the E-plane. The developed TCA can be applied for the generation of high-power electromagnetic environments for the study of intentional electromagnetic interference.

3.
ACS Appl Mater Interfaces ; 15(42): 49642-49652, 2023 Oct 25.
Article in English | MEDLINE | ID: mdl-37831933

ABSTRACT

Flexible pressure sensors possess vast potential for various applications such as new energy batteries, aerospace engines, and rescue robots owing to their exceptional flexibility and adaptability. However, the existing sensors face significant challenges in maintaining long-term reliability and environmental resilience when operating in harsh environments with variable temperatures and high pressures (∼MPa), mainly due to possible mechanical mismatch and structural instability. Here, we propose a composite scheme for a flexible piezoresistive pressure sensor to improve its robustness by utilizing material design of near-zero temperature coefficient of resistance (TCR), radial gradient pressure-dividing microstructure, and flexible interface bonding process. The sensing layer comprising multiwalled carbon nanotubes (MWCNTs), graphite (GP), and thermoplastic polyurethane (TPU) was optimized to achieve a near-zero temperature coefficient of resistance over a temperature range of 25-70 °C, while the radial gradient microstructure layout based on pressure division increases the range of pressure up to 2 MPa. Furthermore, a flexible interface bonding process introduces a self-soluble transition layer by direct-writing TPU bonding solution at the bonding interface, which enables the sensor to achieve signal fluctuations as low as 0.6% and a high interface strength of up to 1200 kPa. Moreover, it has been further validated for its capability of monitoring the physiological signals of athletes as well as the long-term reliable environmental resilience of the expansion pressure of the power cell. This work demonstrates that the proposed scheme sheds new light on the design of robust pressure sensors for harsh environments.

4.
Environ Res ; 237(Pt 1): 116987, 2023 Nov 15.
Article in English | MEDLINE | ID: mdl-37633636

ABSTRACT

Efficiently addressing initial rainwater pollution is crucial for mitigating urban water pollution. However, the performance evaluation of initial rainwater pollution control project is rarely introduced. In this study, the architecture of effective comprehensive engineering measures for improving the water quality of initial rainwater in Anhui Province, China, was described. Three water quality indicators, ammonia nitrogen (NH3-N), chemical oxygen demand (COD), and total phosphorus (TP), were selected to explore the severity of urban pollution caused by initial rainwater under various rainfall scenarios. A single-factor evaluation method was used to contrast and assess the benefits of the initial rainfall interception project in terms of water quality enhancement. Results showed that initial rainfall pollution was gentler under light rainfall conditions but more prominent under moderate and heavy conditions. The percentages of NH3-N, COD, and TP in Lotus Pond that met the tertiary drinking water standard were 100%, 74.91%, and 100% with great improvement, and the average concentrations of NH3-N, COD, and TP in Fushan Road Drainage have decreased by 91.43%, 10.49%, and 57.33% respectively, after the construction of the interception project. These indicated that the nitrogen and phosphorus pollution were successfully controlled by the control techniques in both locations, but COD concentration has to be addressed with more specialized strategies. Overall, the water quality improvement project for initial rainwater pollution plays a great role in effectively governing initial rainwater pollution and improving river water quality, and provides an effective technical reference for urban water ecological environment management.

5.
Int J Mol Sci ; 24(14)2023 Jul 08.
Article in English | MEDLINE | ID: mdl-37510993

ABSTRACT

Immunotherapies including adaptive immune checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR) T cells, have developed the treatment of cancer in clinic, and most of them focus on activating T cell immunity. Although these strategies have obtained unprecedented clinical responses, only limited subsets of cancer patients could receive long-term benefits, highlighting the demand for identifying novel targets for the new era of tumor immunotherapy. Innate immunity has been demonstrated to play a determinative role in the tumor microenvironment (TME) and influence the clinical outcomes of tumor patients. A thorough comprehension of the innate immune cells that infiltrate tumors would allow for the development of new therapeutics. In this review, we outline the role and mechanism of innate immunity in TME. Moreover, we discuss innate immunity-based cancer immunotherapy in basic and clinical studies. Finally, we summarize the challenges in sufficiently motivating innate immune responses and the corresponding strategies and measures to improve anti-tumor efficacy. This review could aid the comprehension of innate immunity and inspire the creation of brand-new immunotherapies for the treatment of cancer.


Subject(s)
Neoplasms , Humans , Neoplasms/pathology , Immunity, Innate , Immunotherapy , T-Lymphocytes , Biology , Tumor Microenvironment
6.
Nanomaterials (Basel) ; 13(5)2023 Feb 25.
Article in English | MEDLINE | ID: mdl-36903734

ABSTRACT

The high energy/power lithium-ion battery using LiNi0.5Co0.2Mn0.3O2 (NCM523 HEP LIB) has an excellent trade-off between specific capacity, cost, and stable thermal characteristics. However, it still brings a massive challenge for power improvement under low temperatures. Deeply understanding the electrode interface reaction mechanism is crucial to solving this problem. This work studies the impedance spectrum characteristics of commercial symmetric batteries under different states of charge (SOCs) and temperatures. The changing tendencies of the Li+ diffusion resistance Rion and charge transfer resistance Rct with temperature and SOC are explored. Moreover, one quantitative parameter, § ≡ Rct/Rion, is introduced to identify the boundary conditions of the rate control step inside the porous electrode. This work points out the direction to design and improve performance for commercial HEP LIB with common temperature and charging range of users.

7.
Immunotherapy ; 15(3): 175-187, 2023 02.
Article in English | MEDLINE | ID: mdl-36727256

ABSTRACT

Background: Only a subset of B-cell lymphoma (BCL) patients can benefit from immune checkpoint inhibitors targeting PD-1/PD-L1. Materials & methods: In the A20 model, SIRPα-Fc and anti-PD-L1 were employed to target CD47 and PD-L1 simultaneously. Flow cytometry, immunofluorescence and quantitative polymerase chain reaction were used to unravel the potential mechanisms. Results: Simultaneously targeting CD47 and PD-L1 activated CD8+ T cells with an increased release of effector molecules. Furthermore, infiltration of F4/80+iNOS+ M1 macrophages was enhanced by the dual therapy. Conclusion: Anti-CD47 therapy could sensitize BCL tumors to anti-PD-L1 therapy in a CD8+ T-cell- and M1-macrophage-dependent manner by promoting cytotoxic lymphocyte infiltration, which may provide a potential strategy for BCL treatment by simultaneously targeting CD47 and PD-L1.


Immune checkpoint inhibitors targeting PD-1/PD-L1 have become effective agents for cancer treatment. However, only a minority of patients benefit from this treatment in the clinic because of the limited response rate. Targeting CD47/SIRPα restores macrophage function and improves the response of antitumor immunity. Here, combination immunotherapy targeting CD47/SIRPα and PD-1/PD-L1 was investigated to increase the response rate and antitumor effect of PD-L1 monotherapy in B-cell lymphoma (BCL). This study broadens the application of the combination therapy and provided a promising strategy for B-cell lymphoma treatment by simultaneous targeting of PD-1/PD-L1 and CD47/SIRPα axis.


Subject(s)
Lymphoma, B-Cell , Neoplasms , Humans , CD47 Antigen , CD8-Positive T-Lymphocytes , Immunotherapy , Lymphoma, B-Cell/drug therapy , Macrophages , B7-H1 Antigen/metabolism
8.
Environ Sci Pollut Res Int ; 30(12): 33475-33484, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36480137

ABSTRACT

Spontaneous combustion of coal seams can produce a high temperature of about 800 ℃, which greatly changes the thermal conductivity of the overlying loess layer. The thermal conductivity of loess plays an important role in ecological restoration design and the calculation of roadbed and slope stability. In this study, loess in northern Shaanxi, China was taken as the research object to measure the mass-loss rate and heat conduction parameters of loess specimens after high temperature. The test results show that, between 23 and 900 °C, with temperature increasing, the mass-loss rate is reduced. And the heat conduction coefficient (λ), specific heat capacity (c), and thermal diffusion coefficient (α) decreased by 48.9%, 23.1%, and 35.6%. This is due to the air thermal resistance effect caused by the increase of pores and cracks in loess specimens after high temperature.


Subject(s)
Hot Temperature , Temperature , Thermal Conductivity , China
9.
Rev Sci Instrum ; 93(8): 084702, 2022 Aug 01.
Article in English | MEDLINE | ID: mdl-36050060

ABSTRACT

An exponential spacing and sinusoidal folded helical (ESSFH) antenna backed with a cavity is developed in this paper. Compared with the conventional helical (CH) antenna, the proposed antenna not only has smaller dimension but also exhibits a wider working bandwidth, a higher gain, and a better circular polarization (CP) characteristic. To reduce the dimension of the helical antenna, a sinusoidal structure is adopted along the circumference of the helix. However, it deteriorates the CP characteristic of the antenna. Therefore, the structure of the exponential helix spacing is introduced into the sinusoidal folded helical (SFH) antenna. Then, to further improve the gain of the ESSFH antenna, its ground plane is replaced by an optimized cavity. Compared with the CH antenna, the helix diameter of the ESSFH antenna Dλ is reduced from 0.32 to 0.23, and its volume is reduced to 53%. The ESSFH antenna backed with a cavity has an impedance bandwidth of 0.43-1.02 GHz, which is much wider than 0.48-0.60 GHz of the CH antenna. Moreover, it has an axial ratio of 1.77, while the axial ratio of the CH antenna is 2.61. In addition, its effective potential gain is 0.56, which is 22% higher than that of the CH antenna.


Subject(s)
Wireless Technology , Electric Impedance , Equipment Design
10.
Rev Sci Instrum ; 93(4): 044705, 2022 Apr 01.
Article in English | MEDLINE | ID: mdl-35489880

ABSTRACT

In this paper, a high-power ultra-wideband radiation system, composed of multiply radiation modules, is developed based on the space-synthesis method. The radiation module mainly consists of a transistorized pulser, a 2 × 2 combined antenna array, and a power divider. To improve the out parameters [the amplitude, the pulse repetition frequency (PRF), and the rise time] of the transistorized pulser based on the Marx circuit, the influence of the traveling wave process on the output pulse must be concerned. Based on the theoretical analysis, the printed circuit board circuit parameters and the circuit structure of the pulser are optimized. To improve the power synthesis efficiency, the pulse jitter characteristic of the pulser is improved by replacing the conventional base triggering mode with the collector voltage ramp triggering mode for the first-stage avalanche transistor in the pulser. The previous optimized antenna array is utilized in this radiation system, which has a better radiation performance in the prescribed aperture area. In addition, based on the gradient microstrip structure, the power divider integrated with the pulser is designed, which has the advantages of wide bandwidth, low loss, and light weight. Experimental results show that the peak effective potential rEp of the radiation system of 20 radiation modules is 221.8 kV, the maximum PRF could reach 10 kHz, and the half-power radiation angles of its radiation field are about 5° in both the E plane and the H plane. More radiation modules could be integrated into the system to achieve a higher electric field in the future.

11.
Environ Sci Pollut Res Int ; 29(36): 54309-54317, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35301626

ABSTRACT

Coal fires refer to fires generated by the self-combustion of coal seams, which have a maximum temperature of 1000 °C. Such fires can significantly alter the properties of surrounding rock and soil. However, in Northern Shaanxi, China, coal resources are abundant, and the buried depth of coal seams is shallow; therefore, coal fires often occur. Because Northern Shaanxi is located in China's Loess Plateau, there is a large amount of loess accumulation on the surface. For this reason, it is imperative to study the effects of high temperatures on loess. In this paper, the loess samples are heat treated at different temperatures (200-1000 °C), and their surface redness (a*) and mass magnetic susceptibility (χ) are measured to simulate the high-temperature effects of coal fires on the loess in northern Shaanxi, and also study its chromaticity changes and abnormal magnetic properties. The results show that (1) the loess χ value is affected by the heat-treatment temperature; at 600 °C, the χ value decreases, increasing rapidly above after 850 °C. Further, the magnetic susceptibility changes significantly. (2) The thermal-induced transformation of ferromagnetic minerals and the buried depth of loess are the main reasons for these changes in magnetic susceptibility and red chroma of loess.


Subject(s)
Coal , Hot Temperature , China , Coal/analysis , Magnetic Phenomena , Soil , Temperature
12.
J Healthc Eng ; 2022: 1112960, 2022.
Article in English | MEDLINE | ID: mdl-35242294

ABSTRACT

In order to explore the reliable clinical characteristics of patients with pulmonary thromboembolism, this paper applies computer statistical analysis methods to the analysis of clinical characteristics of patients with pulmonary thromboembolism. Moreover, starting from the actual situation, this paper combines experiments to study the case, uses sample screening and sample processing to group samples freely, and conducts grouping reliability research through data statistics methods. After verifying the reliability of the grouping, this paper combines the samples to test the effectiveness of the computer statistical analysis method applied to the clinical characteristic analysis of patients with pulmonary thromboembolism and conducts numerical analysis in combination with the comparative analysis method. The results of the research show that the computer statistical method proposed in this paper has a good effect on the clinical characteristics of patients with pulmonary thromboembolism and meets the actual needs of clinical analysis.


Subject(s)
Pulmonary Embolism , Computers , Humans , Pulmonary Embolism/diagnosis , Reproducibility of Results , Research Design
13.
J Neurosurg Spine ; : 1-9, 2022 Feb 11.
Article in English | MEDLINE | ID: mdl-35148517

ABSTRACT

OBJECTIVE: The aim of the present study was to compare the long-term effects of posterior C1-ring osteosynthesis and C1-2 fixation fusion in the treatment of unstable atlas fractures. METHODS: A multicenter, prospective, randomized controlled trial was conducted to analyze 73 patients with atlas fractures who underwent posterior fixation. The intervention group was treated with C1-ring osteosynthesis, and the control group was treated with C1-2 fixation fusion. The patients were followed up for 6 months, 1 year, 2 years, and 5 years after the operation. RESULTS: Fifty-two patients had complete data at the last follow-up. The visual analog scale (VAS) score for neck pain in the intervention group was lower than that in the control group (p < 0.001). The operation time, intraoperative blood loss, radiation dose, bedridden period, hospital stay, and cost in the intervention group were significantly lower than those in the control group (p < 0.001). At the last follow-up, the Neck Disability Index in the intervention group was higher than that of the control group, and the angle of flexion-extension and axial rotation in the intervention group were greater than those in the control group (p < 0.001). CONCLUSIONS: In this study, the authors found that posterior C1-ring osteosynthesis is superior to C1-2 fixation fusion in terms of long-term relief of neck pain and preservation of the physiological function of the cervical vertebrae. This technique is a reliable choice for the treatment of unstable C1 fractures.

14.
Plant Physiol ; 187(4): 2296-2310, 2021 12 04.
Article in English | MEDLINE | ID: mdl-34601582

ABSTRACT

AKT2 potassium (K+) channels are members of the plant Shaker family which mediate dual-directional K+ transport with weak voltage-dependency. Here we show that OsAKT2 of rice (Oryza sativa) functions mainly as an inward rectifier with strong voltage-dependency and acutely suppressed outward activity. This is attributed to the presence of a unique K191 residue in the S4 domain. The typical bi-directional leak-like property was restored by a single K191R mutation, indicating that this functional distinction is an intrinsic characteristic of OsAKT2. Furthermore, the opposite R195K mutation of AtAKT2 changed the channel to an inward-rectifier similar to OsAKT2. OsAKT2 was modulated by OsCBL1/OsCIPK23, evoking the outward activity and diminishing the inward current. The physiological relevance in relation to the rectification diversity of OsAKT2 was addressed by functional assembly in the Arabidopsis (Arabidopsis thaliana) akt2 mutant. Overexpression (OE) of OsAKT2 complemented the K+ deficiency in the phloem sap and leaves of the mutant plants but did not significantly contribute to the transport of sugars. However, the expression of OsAKT2-K191R overcame both the shortage of phloem K+ and sucrose of the akt2 mutant, which was comparable to the effects of the OE of AtAKT2, while the expression of the inward mutation AtAKT2-R195K resembled the effects of OsAKT2. Additionally, OE of OsAKT2 ameliorated the salt tolerance of Arabidopsis.


Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Oryza/genetics , Oryza/metabolism , Phloem/metabolism , Potassium Channels/metabolism , Salt Tolerance/physiology , Crops, Agricultural/genetics , Crops, Agricultural/metabolism , Gene Expression Regulation, Plant , Genes, Plant , Mutation , Phloem/genetics , Potassium Channels/genetics , Salt Tolerance/genetics
15.
ACS Appl Mater Interfaces ; 13(39): 46866-46874, 2021 Oct 06.
Article in English | MEDLINE | ID: mdl-34559512

ABSTRACT

Transparent material has been widely used in product design and has seen a large increase in its use. In this paper, a kind of aesthetically decorative 5 GHz Wi-Fi dielectric resonator antenna (DRA) of aluminum oxynitride (AlON) transparent ceramic has been designed. High-quality-factor AlON transparent dielectric ceramics were fabricated by presintering at 1780 °C and further cold isostatic pressing (CIP) under a 200 MPa argon atmosphere. For a 9.0 mm thick specimen, the in-line light transmittance reached 83%. Optimum dielectric constant (εr = 9.32), quality factor (Qf = 47 960) and temperature coefficient (TCF = -51.7 ppm/°C) was achieved in the AlON transparent ceramic by cold isostatic pressing. As a result, the proposed aesthetically decorative DRA can achieve an impedance bandwidth of 32% (4.48-6.19 GHz), a high radiation efficiency of 85%, and a low cross-polarization discrimination (XPD) of -30 dB. To achieve a broad bandwidth, the proposed antenna was excited in its dominant TE111x mode and higher-order TE113x mode. The proposed antenna is thus an excellent candidate for an indoor decoration Wi-Fi antenna.

16.
Rev Sci Instrum ; 92(7): 074701, 2021 Jul 01.
Article in English | MEDLINE | ID: mdl-34340433

ABSTRACT

In this article, a Narrow-Width Combined Antenna (NWCA) is proposed for the compact design of high-power ultra-wideband (UWB) systems. The dependence of performances on three dimensions of the combined antenna is investigated so as to minimize its size with a given excitation. It indicates that the working process of the combined antenna can be divided into two stages: (1) energy transmitted from the feeding point to the aperture by the TEM horn structure, and during this stage, the passband is determined by the effect of the impedance taper, which is related to the length and aperture impedance of the antenna, and (2) energy radiated to the free space from the aperture, during which the height of the aperture is the dominant factor. Therefore, the three dimensions of the combined antenna can be appropriately adjusted to make the antenna more compact. Thus, the NWCA is designed by reducing the width and making a slight compensation in height and/or length. Compared with the conventional cubic antenna, the aperture area of the developed NWCA is reduced by 47%, whereas the amplitude of the radiating field only reduces by 2.5% with the given pulsed excitation at the cost of a slight decrease in the pulse duration. It demonstrates that the NWCA is an effectively compact design for the combined antenna in the application of the radiation of the high-power UWB pulse.

17.
Sci Total Environ ; 801: 149677, 2021 Dec 20.
Article in English | MEDLINE | ID: mdl-34418617

ABSTRACT

Sudden water pollution incidents (SWPI) are random and harmful, which is a problem that cannot be ignored in ecological environment governance and economic development. Identifying spatial-temporal distribution characteristics of SWPI is essential for the disaster prevention and the early warning of water environment. The Kernel Density (DE) and spatial mean center of SWPI transfer curve were used to explore the characteristics with the dataset of 1174 cases from 2006 to 2018 in China. Results showed that: (1) From the time point of view, there was an overall upward trend in the overall number of SWPI. (2) At a regional scale, Eastern China, Southwest China, and Southern China underwent a high frequency with 69.93% of SWPI. The Fujian, Guangdong and Chongqing provinces were specified as the top 3 provinces with incident frequencies. The Yangtze River Basin and the Pearl River Basin were two regions where water pollution incidents occur more often, more than 50% of incidents among basins in China every year. (3) In general, SWPI presents a northeast-southwest distribution pattern and center of SWPI moves in the direction of west by south. (4) More than half of the incidents (57.24% of the total) were induced by illegal pollutant discharge and production safety accidents.


Subject(s)
Rivers , Water Pollution , China , Economic Development , Water
18.
Nat Commun ; 12(1): 3136, 2021 May 25.
Article in English | MEDLINE | ID: mdl-34035291

ABSTRACT

Structural degradation in manganese oxides leads to unstable electrocatalytic activity during long-term cycles. Herein, we overcome this obstacle by using proton exchange on well-defined layered Li2MnO3 with an O3-type structure to construct protonated Li2-xHxMnO3-n with a P3-type structure. The protonated catalyst exhibits high oxygen reduction reaction activity and excellent stability compared to previously reported cost-effective Mn-based oxides. Configuration interaction and density functional theory calculations indicate that Li2-xHxMnO3-n has fewer unstable O 2p holes with a Mn3.7+ valence state and a reduced interlayer distance, originating from the replacement of Li by H. The former is responsible for the structural stability, while the latter is responsible for the high transport property favorable for boosting activity. The optimization of both charge states to reduce unstable O 2p holes and crystalline structure to reduce the reaction pathway is an effective strategy for the rational design of electrocatalysts, with a likely extension to a broad variety of layered alkali-containing metal oxides.

19.
Rev Sci Instrum ; 92(1): 014709, 2021 Jan 01.
Article in English | MEDLINE | ID: mdl-33514195

ABSTRACT

In this Note, a type of Differential Switched Oscillator (DSWO) system is developed and compared with the conventional single-ended switched oscillator; the power capacity of the DSWO is twice with the same insulation level and twice total length. The DSWO system consists of a differential high-voltage pulsed source, a DSWO, and a pair of differential helical antennas. The differential pulsed source is based on the hydrogen thyratron and pulsed transformer whose peak voltage can theoretically reach ±100 kV to break down the high-pressure switch, whose limiting gas pressure is 25 atm; the DSWO is designed to generate a damped oscillation pulse with a central frequency of 300 MHz, which is also the central frequency of the differential helical antennas. Thus, a damped oscillation pulse can be produced and radiated to generate high-power mesoband circularly polarized electromagnetic fields, and the axial ratio is 1.98. According to the measured results, the central frequency of the developed DSWO is 284 MHz, the percent bandwidth of the radiating field is 11%, and the amplitude of the far-field effective potential is 105 kV.

20.
Ying Yong Sheng Tai Xue Bao ; 32(1): 201-210, 2021 Jan.
Article in Chinese | MEDLINE | ID: mdl-33477228

ABSTRACT

The WinEPIC model was used to simulate the dynamics of soil moisture and water productivity in the deep layer of the dry farm apple orchard of Changwu in the Loess Plateau from 1980 to 2018, aiming to provide a scientific basis for the sustainable development of apple production in the area. The results showed that the average annual yield of apple orchards in Changwu area was 27.37 t·hm-2, the average annual evapotranspiration was 673.66 mm, and the average annual water productivity was 4.07 kg·m-3. The number of water stress days in adult apple trees was mainly affected by rainfall. The average number of stress days in the late stage of apple tree growth was 46.46 d. The soil water content in deep layer began to approach withering humidity as early as 9-year-old apple trees. Water supply in the whole growing season of Changwu area was the dominant factor impacting the yield of orchards. The reduction of effective soil water content in deep soil was the main factor restricting yield enhancement in the middle and late growth stages of apple trees. When there was no sufficient precipitation, apple trees would use soil water from deeper soil layer. Excessive precipitation could not be used by apple trees but could be converted into shallow soil moisture and evaporation if the deep layer had less available water. For the mature apple trees, less than 500 mm or higher than 700 mm of annual water supply would cause a decline in production. For apple orchard at different growth periods, water management strategy should be adjusted according to rainfall conditions in different years. Supplementary irrigation, rainwater retention, covering, and pruning of branches could be used to reduce the unproductive and luxury water consumption of apple trees, delay the appearance of deep dry layer of soil, and avoid the waste of water resources while ensuring the growth of apple trees.


Subject(s)
Malus , Soil , China , Computer Simulation , Water/analysis
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