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In recent years, the FLASH effect, in which ultrahigh dose rate (UHDR) radiotherapy (RT) can significantly reduce toxicity to normal tissue while maintaining antitumor efficacy, has been verified in many studies and even applied in human clinical cases. This work evaluates whether a room-temperature radio-frequency (RF) linear accelerator (linac) system can produce UHDR high-energy X-rays exceeding a dose rate of 40 Gy/s at a clinical source-surface distance (SSD), exploring the possibility of a compact and economical clinical FLASH radiotherapy machine suitable for most hospital treatment rooms.A 1.65 m long S-band backward-traveling-wave (BTW) electron linac was developed to generate high-current electron beams, supplied by a commercial klystron-based power source. A tungsten-copper electron-to-photon conversion target for UHDR X-rays was designed and optimized with Monte Carlo (MC) simulations using Geant4 and thermal finite element analysis (FEA) simulations using ANSYS. EBT3 and EBT-XD radiochromic films, which were calibrated with a clinical machine Varian VitalBeam, were used for absolute dose measurements. A PTW ionization chamber detector was used to measure the relative total dose and a plane-parallel ionization chamber detector was used to measure the relative normalized dose of each pulse.The BTW linac generated 300-mA-pulse-current 11 MeV electron beams with 29 kW mean beam power, and the conversion target could sustain this high beam power within a maximum irradiation duration of 0.75 s. The mean energy of the produced X-rays was 1.66 MeV in the MC simulation. The measured flat-filter-free (FFF) maximum mean dose rate of the room-temperature linac exceeded 80 Gy/s at an SSD of 50 cm and 45 Gy/s at an SSD of 67.9 cm, both at a 2.1 cm depth of the water phantom. The FFF radiation fields at 50 cm and 67.9 cm SSD at a 2.1 cm depth of the water phantom showed Gaussian-like distributions with 14.3 cm and 20 cm full-width at half-maximum (FWHM) values, respectively.This work demonstrated the feasibility of UHDR X-rays produced by a room-temperature RF linac, and explored the further optimization of system stability. It shows that a simple and compact UHDR X-ray solution can be facilitated for both FLASH-RT scientific research and clinical applications. This article is protected by copyright. All rights reserved.

A system for the power combining of dual X-band coaxial magnetrons-based on the peer-to-peer locking is presented in this article. The locking condition of peer-to-peer locking was derived and proposed, in which the frequency pushing effect was taken into account. The frequency pushing parameter of X-band coaxial magnetron was measured by an injection locking experiment. Dual X-band coaxial magnetrons with similar operation characteristics were employed and driven by single modulator to synchronize the pulse generation in the power combining system based on peer-to-peer locking. As the prediction of theoretical derivation, the locking phenomenon emerged with a locked frequency of 9304.41 MHz when the free running frequency of one magnetron was fixed as 9304 MHz. A combined power of 3.09 MW for 3.5 μs pulsewidth with the total power efficiency of 83.5% was achieved in the experiment, which was approximately 1.5 times the maximum peak output power of commercial X-band coaxial magnetron. Due to the measured phase jitter of ±8° caused by the anode current ripple and frequency fluctuation of the magnetrons, the combined power jitter was estimated as ±0.5%, which was acceptable for the system.

Background & Aims: To develop and validate the CoRC model at conventional MRI for diagnosing clinically significant liver fibrosis (≥ F2) and necroinflammation (≥ G2). Materials and methods: This retrospective cohort study recruited 537 patients with biopsy-proven liver fibrosis and necroinflammation at center 1 from May 2015 to Aug 2020 and center 2 between Jan 2011 and Jan 2021. 394 patients were randomly allocated into training (n = 276) and internal test (n = 118) cohorts at center 1.. Automated entire liver segmentation used ResUNet-based Human-in-the-Loop approach. Radiomics features were extracted from the mask on fat-suppressed T2-weighted and delayed enhanced T1-weighted images separately. Radiomics signatures were generated using logistic regression. Radiomics-scores and optimal clinical biomarkers as independent risk factors were integrated into the CoRC models in the training cohort with multivariate logistic regression. Models were tested in independent temporal test cohort at center 1 (n = 96) and an external test cohort from center 2 (n = 47). Diagnostic performance was evaluated by area under the curve, calibrations and decision curve analysis. Results: In the internal, temporal, and external test cohorts, CoRC model 1 yielded AUCs of 0.79, 0.82 , and 0.83 for ≥ F2, meanwhile, CoRC model 2 showed AUCs of 0.86, 0.79, and 0.89 for ≥ G2. ,We compared CoRC models with transient elastography-based liver stiffness measurement (TE-LSM) subgrouply (AUC 0.78 vs.0.79, P = 0.86/0.82 vs. 0.73, P = 0.14 for ≥ F2, whereas 0.88 vs. 0.81, P = 0.16/0.79 vs. 0.74, P = 0.49 for ≥ G2). Conclusions CoRC models exhibited promising diagnostic performances for ≥ F2 and ≥ G2, which could be a potential alternative when TE-LSM is unavailable.

We present a new approach of the passive microwave pulse compression for gigawatt power generation. Two stages of resonant-cavity-based pulse compressors are cascaded and the peak power gain is multiplied to 12. Candidate passive pulse compressors and cascaded schemes are studied theoretically from the perspective of a linear time-invariant (LTI) system. The compact $S$ -band (2.856 GHz) prototype system consists of six correction cavities and two storage cavities, with the ability to flatten the first-stage pulses and generate the two-stage compressed pulses with exponentially decaying waveforms. It compresses power pulses of 100 MW and $3.6~\mu \text{s}$ generated by commercial klystrons to the peak power of 1.2 GW and full-width at half-maximum (FWHM) pulse durations of 100 ns. The pulse phase is controllable and the power can be combined for either input sources or outputs. This would be attractive to various applications, such as high gradient accelerator and hot dense plasma generation.

Background Among recurrent implantation failure (RIF) patients, the rate of successful implantation remains relatively low due to the complex etiology of the condition, including maternal, embryo and immune factors. Effective treatments are urgently needed to improve the outcomes of embryo transfer for RIF patients. In recent years, many researchers have focused on immunotherapy using granulocyte colony-stimulating factor (G-CSF) to regulate the immune environment. However, the study of the G-CSF for RIF patients has reached conflicting conclusions. The aim of this systematic review and meta-analysis was performed to further explore the effects of G-CSF according to embryo transfer cycle (fresh or frozen) and administration route (subcutaneous injection or intrauterine infusion) among RIF patients. Method The PubMed, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched for literature published from the initial to October 2020. The meta-analysis, random-effects model and heterogeneity of the studies with I2 index were analyzed. Stata 15 was used for statistical analysis. Results A total of 684 studies were obtained through the databases mentioned above. Nine RCTs included 976 RIF patients were enrolled in this meta-analysis. Subgroup analysis indicated that G-CSF improved the clinical pregnancy rate for both the fresh and frozen embryo transfer cycles (fresh RR: 1.74, 95% CI: 1.27–2.37, I2 = 0.0%, n = 410; frozen RR: 1.44, 95% CI: 1.14–1.81, I2 = 0.0.%, n = 366), and for both subcutaneous injection and intrauterine infusion (subcutaneous RR: 1.73, 95% CI: 1.33–2.23, I2 = 0.0%, n = 497; intrauterine RR: 1.39, 95% CI: 1.09–1.78, I2 = 0.0%, n = 479), but the biochemical pregnancy rate of the RIF group was also higher than that of the control group (RR: 1.85, 95% CI: 1.28–2.68; I2 = 20.1%, n = 469). There were no significant differences in the miscarriage rate (RR: 1.13, 95% CI: 0.25–5.21: I2 = 63.2%, n = 472) and live birth rate (RR: 1.43, 95% CI: 0.86–2.36; I2 = 52.5%; n = 372) when a random-effects model was employed. Conclusion The administration of G-CSF via either subcutaneous injection or intrauterine infusion and during both the fresh and frozen embryo transfer cycles for RIF patients can improve the clinical pregnancy rate. However, whether G-CSF is effective in improving livebirth rates of RIF patients is still uncertain, continued research on the utilization and effectiveness of G-CSF is recommended before G-CSF can be considered mainstream treatment for RIF patients.

We present a global panel dataset of COVID-19 vaccine policies, with data from 01 January 2020 for 185 countries and a number of sub-national jurisdictions, reporting on vaccination prioritisation plans, eligibility and availability, cost to the individual, and mandatory vaccination policies. For each of these indicators, we recorded who is targeted by a policy using 53 standardised categories. These indicators document a detailed picture of the unprecedented scale of global COVID-19 vaccination rollout and strategy, indicating which countries prioritised and vaccinated which groups, when, and in what order. We highlight key descriptive findings from these data, to demonstrate uses for the data and to encourage researchers and policy makers in future research and vaccination planning. Numerous patterns emerge. For example: some countries prioritised border workers and economic sectors (“eliminator” countries), while others prioritised the elderly and healthcare sectors for the first COVID-19 vaccinations (“mitigator” countries); High Income Countries (HICs) published prioritisation plans and began vaccinations earlier than Low- and Middle-Income Countries (LMICs). Fifty-five countries were found to have implemented at least one policy of mandatory vaccination. We also demonstrate the value of combining this data with vaccination uptake rates, vaccine supply and demand data, and with further COVID-19 epidemiological data. (200 words).

Rapid yet comprehensive neuroimaging protocols are required for patients with suspected acute stroke. However, stroke mimics can account for approximately one in five clinically diagnosed acute ischemic strokes and the rate of thrombolyzed mimics can be as high as 17%. Therefore, to accurately determine the diagnosis and differentiate mimics from true transient ischemic attacks, acute ischemic stroke is a challenge to every clinician.Medical history and neurological examination, noncontract head computed tomography, and routine magnetic resonance imaging play important roles in the assessment and management of patients with transient neurological attacks in the emergency department. This review attempts to summarize how neuroimaging can be utilized to help differentiate the most common mimics from transient ischemic attack and acute ischemic stroke.Although imaging can help direct critical triage decisions for intravenous thrombolysis or endovascular therapy, more detailed medical history and neurological examination are crucial for making a prompt and accurate diagnosis for transient neurological attack patients.

Microwave pulse compressors based on a single resonant cavity operating at polarized modes can be super compact, and corrugated structures can transmit high-power, high-frequency microwave with very low loss. We present an $X$ -band (11.424 GHz) pulse compressor using a corrugated cavity with quarter-wavelength depth corrugations working at polarized HE 1-1-14 modes. The cavity has a high-quality factor ( $Q_{0}$ ) of 116 000 with an inner diameter of less than 7 cm and a length of less than 20 cm, which is more compact compared with smooth spherical and cylindrical cavities for equivalent quality factors. The klystron power can be compressed to a peak power of 150 MW in order to feed two high-gradient accelerating structures designed for the Tsinghua Thomson-scattering X-ray Source (TTX). Theory, design, measurements, and the high-power demonstration of the corrugated pulse compressor are presented in detail. Limitations such as breakdowns and temperature rise of using the corrugated structure as a storage element are also further analyzed.

The concept of free volume underpins the variations in polymer dynamics. Annihilation of free-volume holes through diffusion to surfaces has been proposed to determine the vitrification of the confined polymers. In this work, we assessed the hole diffusion dynamics in glassy thin poly (ethylene terephthalate) films with various thicknesses using a strategy based on covering the film surface with crystals of different sizes, which allows for changing the hole diffusion efficiency, thus tuning the glass transition temperature of the thin film (Tgfilm). The apparent activation energy for hole diffusion (Ea,hole) in the thin films was elucidated by modeling the correlation between Tgfilm and surface coverage of crystals using the free-volume hole diffusion model. Our results demonstrated a trend of linear decrease in Ea,hole with the increasing inverse film thickness (h–1), suggesting that the presence of a free surface with faster dynamics promotes hole diffusion in thin films. This finding demonstrates that the free volume release in thin films and thus the confined polymer dynamics can be modulated by changing the free surface properties of the films., B.Z. acknowledges financial support from Natural Science Foundation of China (Grant nos. 21973083) and Projects of International Cooperation and Exchanges NSFC (Grant nos. 22011530456). D.C. acknowledges financial support from the project PGC2018-094548-B-I00 (MICINN-Spain and FEDER-UE) and the project IT-1175-19 (Basque Government).

The chemical stability and content of organic functional groups significantly affect the application of materials in the field of adsorption. In this study, we quantitatively studied the effect of in-situ co-condensation and post grafting on the physico-chemical properties and sorption properties of modified mesoporous silica. The results showed that the grafting method changed the morphology of mesoporous silica while the in-situ method kept the spherical morphology well, and the amino groups were both successfully introduced into the materials. Besides, the amino content of the material prepared by in-situ method (ami-MSN) was 2.71 mmol/g, which was significantly higher than the 0.98 mmol/g of the grafting method (ami-g-MS). Moreover, the chemical stability of functional groups in ami-MSN was much better than ami-g-MS. Furthermore, ami-MSN showed better capability in removing toxic metals of Pb, Cd, Ni, and Cu, and the removal efficiency of Pb reached 98.80%. Besides, ami-MSN exhibited higher dynamic CO2 adsorption of 0.78 mmol/g than ami-g-MS of 0.34 mmol/g. This study revealed the relationship between modification methods and the modification efficiency, functional groups stability, and sorption properties through quantitative comparative studies, which provided a reference for preparing modified mesoporous silica materials with high sorption properties.

The limits of beam-to-radio frequency (RF) efficiency, which are achievable using klystrons, are discussed in this article. Interaction between the electron beam and RF field in the output cavity is also investigated. A 100% efficiency could be achieved for certain RF fields and point-like beams. However, efficiency is reduced when fringe field, space–charge effect, and transverse beam distribution are considered. Numerical calculations on these factors are presented to investigate the power extraction mechanism in the output cavity, which will help in the optimization of future klystron designs. Large-signal klystron simulation code KlyC is used for 1-D and 1.5-D calculations.

This study investigates citizen assessments of government actions in the COVID-19 outbreak in China. Empirical analyses based on a large-scale online survey indicate that the Chinese public expects the government to improve its support for the frontline medical staff, management of public stress and anxiety, and disclosure of government information. Specifically, indirect exposure to COVID-19 through second-hand information is negatively associated with citizen assessments of government actions; by contrast, the first-hand frontline experience with the epidemic is positively associated with citizen assessments of government actions. Findings suggest that citizens with first-hand experience might be more able to judge government actions under the actual constraints of resources and opportunities, and are less likely to overemphasize the costs or risks associated with government actions than others without frontline experience. Our work suggests that governments should effectively communicate detailed information regarding government actions to the public during public health emergencies, as more informed citizens might be more supportive of governments with limited resources and, probably, more actively collaborate with governments.

The mechanical response characteristics of rocks under cyclic loading conditions are crucial factors for evaluating and analyzing the stability of rock mass during underground excavation. In this study, based on fractal theory and a series of tests using the MTS815.02 rock mechanics test system, the classification and fractal characteristics of limestone specimen fragments are investigated. The results show that limestone specimens subjected to cyclic loading can generate more small-sized fragments than conventional compression, but the large-fragment-producing abilities of the two tests exhibit small difference. The mass fraction of the fragments in the cyclic loading test is obviously greater than that in the conventional test when the fragment size is less than 4.75 mm; however, only a small difference is observed between the cyclic loading tests with frequencies of 0.25 and 0.5 Hz. In the same type of test, a confining pressure is helpful in reducing the fragmentation of limestone specimen. As the size interval decreases, the shapes of limestone fragment transition from rectangular to long slice and then to square. The results also indicate that the confining pressure has a significant influence on the size-quantity and size-mass fractal dimensions of limestone fragments. The former has a positive correlation with the confining pressure, whereas the latter decreases with confining pressure. The conclusions obtained in this investigation can enrich the theoretical research on the failure response and mechanism of rock under cyclic loading conditions.

Due to inappropriate mining practices, water-conducting fracture zones can develop in an aquifer, not only destroying the surface-water environment but also causing water inrush, even hurting or killing workers. To avoid such disasters, investigating and simulating the evolution mechanism of water-conducting fractures are becoming a research focus in mining engineering, especially regarding the organisation and development of fractures. Our work mainly involved the design of low-strength analogous materials and the simulation of fracture evolution for weak-roof problems in shallow seam mining based on a self-built experimental hydromechanical coupling system. The experimental results show that the vertical stress in the roof increases first as the working face approaches and finally decreases to near its initial value as the working face passes. The relationship between fracture depth and coal-seam excavation distance is obviously nonlinear. The leakage velocity of surface water remains stable in the early stage of excavation and increases when the fracture develops through the main aquifuge. The maximum fracture depth is 76.18 m for the Yili coal mine with weak roofs and shallow coal seams. In addition, we numerically simulated and verified the evolution patterns with the FLAC3D platform. The simulated fracture depth of the Yili coal mine agreed with the in situ borehole observation very well and was more accurate than the output of the empirical formula. Our work provides new methods and relevant data for research on the evolution of water-conducting fractures in weak roofs during shallow seam mining.

Remote ischemic perconditioning (RIPerC) could improve neuronal damage and inhibit inflammation and apoptosis. We conducted an in-depth exploration of the protective mechanism of RIPerC in cerebral ischaemia injury. In this study, a middle cerebral artery occlusion (MCAO) mouse model was built. According to whether to undergo RIPerC treatment and the duration of cerebral infarction, mice were divided into 5 groups: Sham group, MCAO 3.0 h group, MCAO 4.5 h group, MCAO 3.0 h + RIPerC group, and MCAO 4.5 h + RIPerC group. Overexpressed or silenced miR-153-5p was transfected into the cells to analyse the effects of oxygen-glucose deprivation (OGD) treatment on Neuro-2a cell viability, apoptosis, and related gene expressions by performing quantitative real-time polymerase chain reaction (qRT-PCR), MTT assay, flow cytometry, and Western blot. Bioinformatics analysis, qRT-PCR, dual-luciferase experiment, and RNA immunoprecipitation (RIP) were used to screen and verify the miRNA and downstream mRNA-targeted Toll-like receptor 4 (TLR4). The rescue test further verified the effects of the above target genes and miR-153-5p on the apoptosis of OGD-injured cells, apoptosis-related proteins, and the p65/IkBa pathway. The plasma levels of miR-153-5p in 68 patients with ischaemic stroke were detected within 6 hours of onset, and the patients were followed up for 3 months. We found that, in in vivo studies, RIPerC treatment inhibits cerebral infarction volume and neurological damage, and promotes the expression of miR-153-5p in the MCAO animal model. The expression of miR-153-5p in OGD cells was inhibited, and its upregulation protected Neuro-2a cells. TLR4 was predicted to be the target gene of miR-153-5p and could offset the effect of miR-153-5p mimic on OGD cell protection after up-regulating TLR4. TLR4 overexpression promoted the activation of OGD on the p65/IkBa pathway. Compared with the high plasma miR-153-5p group, the 3-month overall survival rate of patients with ischaemic stroke in the low plasma miR-153-5p group was significantly lower (c2 = 5.095, p = 0.024). In conclusion, RIPerC intervention inhibits the damage caused by cerebral ischaemia partially through the miR-153-5p/TLR4/p65/IkBa signalling pathway.

In patients with 1-3 embryos available on day 3, does blastocyst transfer reduce the chances of a clinical pregnancy by cancelling transfer cycles compared with cleavage transfer?This retrospective observational study included 423 IVF cycles performed from 1 January 2019 to 31 December 2020 at the Center for Reproduction and Fertility of the Second Affiliated Hospital of Kunming Medical University. Cleavage transfer was performed in 267 cycles and blastocyst transfer was performed in 156 cycles. The primary outcome was the ongoing pregnancy rate, and the secondary outcomes were clinical pregnancy rate and embryo cessation rate. Univariate analysis was performed to compare outcomes. A logistic regression analysis was performed to explore the association between transfer stage and ongoing pregnancy rate.No differences were observed in the ongoing pregnancy rate (25.84% versus 26.92%; odds ratio [OR] 0.95; 95% confidence interval [CI] 0.61-1.50; P = 0.82) and embryo cessation rate (83.48% versus 85.75%; OR 1.19; 95% CI 0.82-1.75; P = 0.40) between the two groups. Logistic regression analysis showed no association between transfer stage and ongoing pregnancy rate (OR 1.06; 95% CI 0.64-1.73).Blastocyst transfer does not reduce the chances of a clinical pregnancy. These results support the proposal of blastocyst transfer in patients with 1-3 embryos available on day 3.

Shortening the pulse length of input power is a possible approach to raise the accelerating gradient limit of normal conducting structures. We present a novel design of a parallel-coupled structure that operates at ultrashort input power pulses. The principle of the design is to shorten the filling time of the whole structure by feeding the cells individually so that the duration of power transmission between cells can be saved. An X-band (11.994 GHz) parallel-coupled structure design with a 10 ns pulse length is presented in this work. Previous high-power tests of X-band structure prototypes show that a gradient of $120\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ could be achieved for a 200 ns pulse length. Based on the law requiring that ${E}^{30}{t}^{5}=\text{constant}$, this 10-ns-structure design should be able to reach a gradient of $200\text{ }\text{ }\mathrm{MV}/\mathrm{m}$. A detailed circuit model and real-time electromagnetic field simulation methods for designing the parallel-coupling structure are also presented and discussed in this paper.

In this paper, a low-loss 90°-bending design in femtosecond laser-induced double-line waveguides is theoretically proposed and experimentally demonstrated. The bending is realized based on the total internal reflection of a corner mirror (made by precise diamond blade dicing) located at the intersection of a pair of waveguides perpendicular to each other. The waveguide bending performance was birefringence free, with the insertion loss of each bending below 0.8 dB. This method provides great flexibility and has great potential for the design of integrated photonics based on femtosecond laser-inscribed crystalline materials.

Many prototypes of all stainless steel high-power loads have been developed in Tsinghua University to meet the needs of high-power test systems for different microwave bands. The loads, which work at the S-band with a center frequency of 2856 MHz, are based on a waveguide structure with regular grooves. These loads are tested at 290 MW peak power successfully. This study presents the design, simulation, fabrication, high-power test results and analysis of multipactor phenomenon.

This paper reports on the design, fabrication, RF measurement, and high-power test of a prototype accelerator—such as 11.424 GHz with 12 cells—and a traveling wave of two halves. It was found that the unloaded gradient reached 103 MV/m during the high-power test and the measured breakdown rate, after $$3.17\times 10^7$$ pulses, was $$1.62\times 10^{-4}$$ /pulse/m at 94 MV/m and a 90 ns pulse length. We thus concluded that the high-gradient two-half linear accelerator is cost-effective, especially in high-frequency RF linear acceleration. Finally, we suggest that silver-based alloy brazing can further reduce costs.

A 2856-MHz, π-mode, seven-cell standing-wave deflecting cavity was designed and fabricated for bunch length measurement in Tsinghua Thomson scattering X-ray source (TTX) facility. This cavity was installed in the TTX and provided a deflecting voltage of 4.2 MV with an input power of 2.5 MW. Bunch length diagnoses of electron beams with energies up to 39 MeV have been performed. In this article, the RF design of the cavity using HFSS, fabrication, and RF test processes are reviewed. High-power operation with accelerated beams and calibration of the deflecting voltage are also presented.

IntroductionTherapies targeting histone deacetylase (HDAC) have gained wider attention in the treatment of various clinical conditions. However, the use of HDAC inhibitors in pre-clinical trials in the case of Parkinson’s disease (PD) is very limited. In the present study, the HDAC inhibitor, entinostat, was tested in animals induced with Parkinson’s disease experimentally.Material and methodsWistar male rats (150 ±10 g) were administered with rotenone (2 mg/kg/day, s.c.) for 21 days to induce PD, while entinostat (20 mg/kg) was given intraperitoneally. Then, the neurological functions, PD markers, and HDACs were analysed in the control and experimental animals.ResultsThe results demonstrated that rats that received entinostat displayed progressive motor, behavioural, and neurological function with attenuated α-synuclein and improved tyrosine-hydroxylase compared to control cells. Moreover, the induction of PD in rats demonstrated reduced levels of H2S, dopamine, 3, and 4-dihydroxyphenylacetic acid (DOPAC), and increased monoamine oxidase activity in PD rats. However, the rats that received entinostat demonstrated progressive levels of dopa and DOPAC, with attenuated levels of HDAC-2, -4, and -6 mRNA in the PD rats compared to controls. On the other hand, elevated (p < 0.01) levels of PD marker genes such as GDF3 and NMDA2b were reduced, with a significant increase in neuroprotective genes such as VDAC3 and CBX5 in entinostat-supplemented rats.ConclusionsThe study results suggest that inhibition of HDAC systematically improves the neurological functions, and hence treatments, emphasizing that HDACI, as the speculated mechanism, will be a promising mode of treatment in PD.

This study presents the RF design of a linear accelerator (linac) operated in single-bunch mode. The accelerator is powered by a compressed RF pulse produced from a SLED-I type RF pulse compressor. The compressed RF pulse has an unflattened shape with a gradient distribution which varies over the structure cells. An analytical study to optimize the accelerating structure together with the RF pulse compressor is performed. The optimization aims to maximize the efficiency by minimizing the required RF power from the generator for a given average accelerating gradient. The study shows that, owing to the compressed RF pulse shape, the constant-impedance structure has a similar efficiency to the optimal structure using varying iris apertures. The constant-impedance structure is easily fabricated and is favorable for the design of a linac with a pulse compressor. We utilize these findings to optimize the RF design of a X-band linac using the constant-impedance accelerating structure for the Tsinghua Thomson X-ray source facility.

Objective: To examine the effect of autophagy on cerebral damage caused by different models and test the hypothesis that its protection mechanism acts via inhibiting expression of neuroinflammatory mediators. Methods: Autophagy was induced by rapamycin treatment. Cerebral damage was induced using models of IL-6 treatment, oxygen glucose deprivation/reoxygenation (OGD/R) in vitro, and middle cerebral artery occlusion (MCAO) in vivo. The effect and mechanism of autophagy was examined and assessed in terms of cell viability, infarction size in brain tissue, neurological score, production of inflammatory mediators IL-1β and IL-6, transcription and protein expression of autophagy markers beclin-1 and LC-3II in different experimental groups. Results: Autophagy triggered by rapamycin could protect neurons from IL-6-induced injury and astrocytes from OGD/R-induced injury in vitro and in rat brain tissue from MCAO in vivo. Autophagy significantly increased cell viability, attenuated cerebral infarction and improved neurological scores. It also inhibited production of the IL-1β and IL-6 and elevated the expression of beclin-1 and LC-3II. Conclusions: Autophagy can inhibit the inflammatory response and reduce cerebral I/R injury. There was a relationship between the extent of protection and (i) the level of the autophagic response, (ii) the stage of the cerebral I/R injury, and (iii) the time of intervention.

Although the inactivation of BRM plays oncogenic roles in tumorigenesis, regulation mechanism is rarely studied in clear cell renal cell carcinoma (RCC). Thus, we aimed to investigate the mechanism of BRM inactivation and explore the tumor suppressing roles of BRM in the development of clear cell RCC. We verified that hypermethylation of the BRM promoter was correlated with decreased expression of BRM by multi-omics analysis based on the TCGA database. This result was further confirmed in our own tumor tissues. Moreover, BRM inhibited the ability of proliferation and invasion of RCC cells in vitro. Consistent with this, BRM overexpressing virtually inhibited the xenograft tumor growth of ACHN cells in vivo. Finally we found that BRM promoted cell apoptosis and cellular cycle arrest in G2/M. In conclusion, our study confirms that the hypermethylation of BRM promoters plays oncogenic roles by the transcription inhibition of BRM in RCC, and the tumor suppressor gene BRM inhibits RCC cell vitality in vitro and in vivo.

We designed and fabricated an S-band compact pulse compressor with a single spherical resonant cavity and an RF polarizer for the S-band high power test facility at Tsinghua University. The average power gain of the pulse compressor was optimized to 5.2 with input pulse length of 3.6 μ s and a compression ratio of 12. This pulse compressor will replace the existing SLED-type pulse compressor with two cylinder resonant cavities, which makes the RF system of the high-power test facility compact. The RF design, mechanical design and cold test of the pulse compressor are presented in this paper.

First principle based density functional theory (DFT) was used to calculate the step-by-step hydrogenation and dissociation reaction network of carbon monoxide (CO) over Co-doped Cu(111) surface as a model for understanding the lateral interaction of surface hydroxyl species (OH) on these reactions. We discussed the C O bond length and the adsorption energy changes of reaction intermediates under different adsorption circumstances for purpose of making out the effect of surface hydroxyl on the reaction selectivity. Reaction intermediates co-adsorbed with H atom and hydroxyl could undergo H-assisted or OH-assisted routes. The calculations show that the OH-assisted route prefers with the formation of COH, CHOH and CH2OH while general H-assisted route prefers with the formation of HCO, CH2O and CH3O. Considering the rather low activation barrier of COH, CHOH and CH2OH to form CHX, the existence of hydroxyl on the surface is in favor of boosting the CHX and suppressing the methanol.

A novel X-band (11.424 GHz) radio frequency (RF) power splitter has been designed, fabricated and tested at Tsinghua University. With E-bend waveguide structures and a modified concave bottom polarizer introduced in this work, a compact geometry is achieved. The RF power division ratio of two output ports can be adjusted arbitrarily by changing the position of a short circuit piston, controlled by a servo motor precisely. The input port maintains a good match at any output ratio. The parameters are optimized to acquire high RF power transmission capacity and large bandwidth . The cold test indicated that the max input reflection is −33.1 dB and the max output transmissions are −0.07 dB and −0.12 dB respectively, which agrees with the simulation results well. The high-power test was operated on Tsinghua High Power Test Stand. After days of conditioning, the RF power splitter can be operated steadily at 53 MW 250 ns input power with 20 Hz repetition frequency.

Studies on beam break up instability are carried out in a 10-MeV travelling-wave linear accelerator test stand for irradiation in Tsinghua University. The high-order modes and the radio frequency parameters are calculated and analysedin the structure with a high Q value. The main frequency components of the wakefield in different accelerating cavity sections are simulated and compared. Results show several trapped modes in the bunching section. A tracking code is built in MATLAB to simulate the dynamics. Then, many investigative experiments are carried out in the test stand with a wake-field measurement system for high-order mode sampling analysis. The micro growth process of the high-order modes is obtained, and the main deflecting modes are analysed. The simulation and the experiments reveal the detailed mechanism of beam break up and prove that instability is mainly caused by the trapped modes in the bunching section.

The Compact Linear Collider (CLIC) utilizes two 2.5-km-long normal-conducting linear accelerators (LINACs) to produce a drive beam with 140 μ s pulse length at a repetition rate of 50 Hz. This setup is relatively expensive in the early stages due to both the length of the drive beam LINACs and the amount of the power sources for one drive beam complex are the same in all energy stages. A new concept of accelerating the CLIC drive beam in superconducting LINACs as an alternative scheme is investigates in this work. This scheme requires a minimal number of power sources at the early stages of the CLIC and consequently has the potential to reduce the entry cost. A dimensionless parameter named capacity factor η which determines the number of the superconducting structures and the power is introduced. Two proof-of-concept schemes to compensate the beam-loading effect are also proposed in this paper. The mixed-structure scheme finally selected as the nominal design achieves an optimum η of approximately 1.16 compared to a value of 50.5 without the beam-loading compensation. A rough estimation on the cost of this scheme has also been studied.

Purpose: To compare the efficacy and safety of computed tomography (CT)–guided 125I seed implantation with second-line chemotherapy in treatment of oligorecurrence non–small cell lung cancer after failure of first-line chemotherapy. Methods: Data of oligorecurrence non–small cell lung cancer patients after failure of first-line chemotherapy at two institutions were retrospectively reviewed from January 2013 to July 2018. A total of 53 patients who received the treatment of 125I seed implantation or second-line chemotherapy were eligible for this study. In group A, 25 patients, 84 lesions, received CT-guided permanent 125I seed implantation, whereas in group B, 28 patients, 96 lesions, received second-line chemotherapy. The outcomes were measured in terms of disease control rate, overall survival, quality of life, and complications. Results: The median follow-up period was 13 months (range, 5–42 months). Disease control rate in group A was higher than that in group B (70.8 vs. 42.3%, P = 0.042) at 6 months after treatment. The median overall survival was 12.8 months (95% confidence interval, 10.5–15.1 months) in group A and 15.2 months (95% confidence interval, 12.2–18.2 months) in group B, with no significant difference (P = 0.847). Since the fourth month, the number of patients in group A with a non-decreasing Karnofsky Performance Scale score was more than that in group B (P < 0.05). The incidence of grade 3 or higher complications especially hematologic toxicity in group A was significantly lower than that in group B (P < 0.05). Conclusion: Radioactive 125I seed implantation is safe and feasible in selected non–small cell lung cancer patients with oligorecurrence after failure of first-line chemotherapy and seems to provide a better long-term quality of life in these patients compared with second-line chemotherapy.

PURPOSE: The aim of this study was to evaluate the role of interleukin 6 in embryo development in the in vitro fertilization cycles. METHODS: This was a retrospective cohort study. One hundred and three women undergoing in vitro fertilization and embryo transfer due to a tubal factor were included in the study. The follicular fluid IL-6 levels on oocyte retrieval day from each patient were determined by ELISA. The relationships between follicular fluid IL-6 levels and IVF cycle parameters were investigated. RESULTS: The levels of follicular fluid IL-6 were not affected by the use of drugs for superovulation or by estrogen. In addition, follicular fluid IL-6 levels did not affect the number of oocytes retrieved or the MII oocyte rate. High levels of follicular fluid IL-6 correlated with a significant increase in the rates of clinical pregnancy. Follicular fluid IL-6 levels did not affect the cell number or the blastomere symmetry of day 3 embryos, but it did significantly reduce the embryo fragmentation rate. CONCLUSIONS: High levels of follicular fluid IL-6 improved the rates of clinical pregnancy and reduce embryo fragmentation.

A compact X-band correction cavity chain (CC) has been successfully designed, fabricated and high power tested for the Compact Linear Collider (CLIC) project. The CC consists of eight spherical cavities and four polarizers, and each spherical cavity has a ${Q}_{0}$ of 45 000 and a diameter of 7 cm. The compact CC can correct a decaying pulse shape generated by a storage cavity without need of low efficiency pulse modulation or a solution based on long delay lines. A flattop output with small ripples can be obtained if the CC and the storage cavity are matched. Experiments of the CC with a barrel open cavity (BOC) were conducted on the XBOX2 test facility at CERN, and the high power results match the theoretical calculations. The appliance of the CC only reduces the pulse compression efficiency by 6% relatively if the transmission attenuation is ignored.

The Xian gamma-ray light source (XGLS) is a proposed novel high brightness gamma-ray source based on inverse Compton scattering (ICS) between the high brightness electron and laser beams. The photoinjector of the accelerator is one of the main components that determines the electron beam quality and related gamma-ray parameters [Phys. Rev. Accel. Beams 21, 030701 (2018)PRABCJ2469-988810.1103/PhysRevAccelBeams.21.030701; 20, 080701 (2017)PRABCJ2469-988810.1103/PhysRevAccelBeams.20.080701; 8, 100702 (2005)PRABFM1098-440210.1103/PhysRevSTAB.8.100702]. In order to reduce the risk of this project, a photoinjector including a laser-driven photocathode rf gun, two S-band tubes, and a diagnostic section was constructed and installed from 2016, serving as a pilot plant for the development of the key technologies for the projects. The injector is designed to deliver high quality electron bunches of typically 500 pC charge and ∼120 MeV energy with low emittance and jitter at 10 Hz repetition. Initial system commissioning with an electron beam was finished in the end of 2017, with a goal of a stable 0.6–0.7 mm mrad emittance in a 500-pC bunch clearly demonstrated. In this paper, we report the experimental results and experience obtained in the commissioning, including rf gun, drive laser system, timing and synchronization system, and beam diagnostics.

An experiment is presented to study the higher-order mode (HOM) suppression of X-band choke-mode structures with a vector network analyzer (VNA). Specific radial line disks were built to test the reflection from the corresponding damping load and different choke geometries. The mismatch between the radial lines and the VNA was calibrated through a special multi-short-load calibration method. The measured reflections of different choke geometries showed good agreement with the theoretical calculations and verified the HOM absorption feature of each geometric design.