Search

Background The gradual increase in blood lipid levels is becoming a significant public health concern. The role of diet in the development of dyslipidemia is crucial. Traditional nutritional epidemiology mainly focuses on individual foods or food groups. However, in our daily lives, we do not only consume isolated nutrients or specific foods, which makes it challenging to determine the specific impact of individual dietary components on dyslipidemia. Currently, there is a lack of research both domestically and internationally that investigates the relationship between dietary patterns and dyslipidemia in the population of Southern Jiangxi (Gannan) . Objective To analyze the relationship between dietary patterns and dyslipidemia in Southern Jiangxi, with the aim of contributing to evidence-based nutritional policies. Methods Data from the Gannan chronic disease cohort 2020 survey data. A multi-stage stratified cluster random sampling method was used to select research participants among permanent residents aged 35 and above in Southern Jiangxi from July to August 2020. Demographic data were collected through standardized questionnaires and physical examinations. Fasting blood glucose and lipid levels were measured. Dietary surveys utilized a food frequency questionnaire, and patterns were identified through factor analysis. The patterns were categorized into quartiles (Q1-Q4) based on factor scores. Logistic regression was used to assess the impact of patterns on dyslipidemia. Results The study included 1 508 residents, with a prevalence of dyslipidemia of 36.07% (544/1 508). Residents who consumed adequate amounts of water, did not have a history of hypertension, and had a history of diabetes showed a higher prevalence of dyslipidemia (P

In order to meet the power source requirements of C-band linear accelerators for industrial applications, a C-band high power klystron operating at a frequency of 5 712 MHz was developed. For this klystron, the development objective of the output power is no less than 3.5 MW and the efficiency is no less than 35%. During the entire design process, the output power was optimized to over 4 MW and the power efficiency over 40% to compensate for the disadvantage effects caused by manufacturing and testing errors in the development processes. Firstly, the electron optics system with a Pierce gun and a combination of five forward and one reverse focusing coils was designed. The Pierce gun with a perveance of 2 μP was adopted and the beam voltage and current were chosen as 120 kV and 83.3 A. By iteratively calculating the structure of the electron gun with EGUN code and optimizing the magnetic field between the electron gun and the beam-wave interaction section, the final electron beam pass rate reaches 100% and the fluctuation of the beam envelop is only 4.8%. Secondly, the efficiency optimization and PIC simulation of the beam-wave interaction section were carried out using the one dimensional AJDISK code, 1.5 dimensional KlyC code and three dimensional CST code. The scheme of six resonant cavities was ultimately determined and the basic cavity parameters were optimized based on the principles of stagger tuning. The simulation results of different codes all indicate that the efficiency can reach above 46.5%, and the output power can all reach above 4.650 MW. And the influence of frequency errors and output external quality factor on efficiency was also analyzed to guide the manufacturing process. After that, the mechanical structure of cavities was designed and all cavities were manufactured with oxygen free copper. The cold test and tuning of all cavities were carried out and the frequency error is mostly within the range of ±5 MHz, which basically does not affect the output power. Finally, the electron gun, the beam-wave interaction section and the collector were welded together. And the high power test was conducted immediately after the first high power C-band klystron protype was completed. When the electron gun operates at the voltage of 115 kV and current of 79.6 A, the klystron peak output power reaches 3.52 MW, the gain reaches 45.5 dB and the efficiency reaches about 38.5%. The high power test results show that this C-band high power klystron achieves the expected development goals.

【Objective】 Rice in southern China is traditionally grown in paddy fields and improving its fertilizer use efficiency and reducing greenhouse emissions is critical to helping achieve the mandatory goal of zero-increase in agrochemical application without compromising crop yield. This paper presents the findings of an experimental study on combined effect of tillage and nitrogen application on N2O emission and mineral N concentrations in surface water of the paddy fields. 【Method】 The experiment was conducted in a double-cropping rice field and involved four tillage treatments: zero tillage (T), micro tillage (C), rotary tillage (R), and smash ridging tillage (S). For each tillage treatment, there were two N fertilizations: conventional N application at 1 225 kg/hm2 (N1) and reducing N application to 150 kg/hm2 (N2). N2O emission and mineral N concentration in the surface water in each treatment were measured 1, 3, and 5 days after N fertilization at different growth stages of the rice. 【Result】 ① One day after N fertilization, ammonium concentration in the surface water increased rapidly to a peak one and then declined quickly. In the conventional fertilization (N1) where N was applied at both tillering and booting stage, zero-tillage increased ammonium concentration in the surface water by 4.7%~532.6%, compared to other treatments. Overall, nitrate and nitrite concentrations in the surface water of all treatments were in the range 0.08~0.20 μg/mL and less than 0.12 μg/mL, respectively. ② Reducing N application and applying it as basal fertilization and topdressing at tillering and booting stages, TN2 reduced N2O emission more than other tillage treatments. ③ N2O emission was negatively correlated to ammonium concentration in the surface water 1~5 days after N fertilization, with the correlation coefficient varying from -0.509~-0.300, depending on the timing of the fertilization. 【Conclusion】 After N fertilization, ammonium became the primary inorganic nitrogen in the surface water. Ammonium concentration of the surface water 1~5 days after the fertilization impacted N2O emissions, irrespective of the timing of the fertilization.

In order to develop a compact electron linear accelerator, a C-band on-axis coupled standing wave accelerating tube operating at the frequency of 5 712 MHz was developed in this paper. The designed beam energy is 6 MeV, and the designed pulse beam current intensity is greater than 80 mA. Firstly, in order to achieve the compact goal, the beam dynamics design was carried out based on the RF phase focusing theory. By designing the phase velocity distribution and electric field distribution in the whole tube reasonably, the longitudinal bunching and transverse focusing of the electron beam were realized simultaneously without external focusing magnetic field. Secondly, the structure of this C-band accelerating tube was optimized after establishing the equivalent circuit model to obtain the required electric field distribution. This accelerating tube adopted π/2 mode onaxis coupled standing wave structure and was composed of three bunching cavities and nine uniform accelerating cavities with a total length of about 284 mm. Through the analysis of the equivalent model, the relationship between the cavity parameters and the coupling coefficient between adjacent cavities were revealed. After adjusting the basic parameters of each cavity, the structure of this tube was determined and the required electric field distribution was obtained. Then the input coupler was designed to match the coupling requirement and the RF field got from the simulation of the whole tube was used in the beam dynamics validation calculation. At last, cavities were brazed together after tuned to the designed frequency and the cold test and highpower test of this tube were carried out. The reflection parameters of this tube were tested in the vacuum condition. The test results show that the operating frequency is 5 7136 MHz, the reflection coefficient at the operating frequency is -16.5 dB, and the corresponding input coupling is 1.35, which meets the designed requirements. The electric field distribution was tested according to the bead-pull measurement method and it’s consistent with the designed field distribution. In the high-power test, the tube was driven by a C-band magnetron which delivered a 2.5 MW peak power, 4 μs width pulse with a repetition rate of 250 Hz. An X-ray target was placed at the beam exit and the maximum dose rate at 1 m behind the target is 845 cGy/min, which indicates that the beam pulse current is 84.5 mA. Based on the half-value-layer measurement methods, the test result shows the electron beam energy can reach 6 MeV. These test results verify the validity of the development process of C-band 6 MeV on-axis coupled standing wave accelerating tube.