Novel compact and lightweight coaxial C-band transit-time oscillator

Compactness and miniaturization have become increasingly important in the development of high-power microwave devices.Based on this rising demand,a novel C-band coaxial transit-time oscillator(TTO)with a low external guiding magnetic field is proposed and analyzed.The proposed device has the following advantages:simple structure,short axial length,high power conversion efficiency,and low external guiding magnetic field,which are of great significance for developing the compact and miniaturized high-power microwave devices.The application of a shorter axial length is made possible by the use of a transit radiation mechanism.Also,loading the opening foil symmetrically to both ends of the buncher helps reduce the external magnetic field of the proposed device.Unlike traditional foils,the proposed opening foil has a circular-hole;therefore,the electron beam will not bombard the conductive foil to generate plasma.This makes it possible to realize long pulse and high repetition rate operation of the device in future experiments.Through numerical calculation and PIC particle simulation,the stability of the intense relativistic electron beam(IREB)and the saturation time of the device are improved by using the conductive foil.The voltage and current of the diode are 548 kV and 11.4 kA,respectively.Under a 0.4-T external guiding magnetic field,a C-band output microwave with a frequency of 4.27 GHz and power of 1.88 GW can be generated.The power conversion efficiency of the proposed device is about 30%.

Novel transit-time oscillator(TTO) combining advantages of radial-line and axial TTO

A novel transit-time oscillator(TTO)is proposed in this paper.An axial cathode which has been widely used in high power microwave(HPM)source and an extractor with radial feature are adopted.In this way,the inherent advantages of axial and radial TTO,both of which can be utilized as high-quality intense relativistic electron beam(IREB),can be generated and the power capacity is also increased.The working mode isπ/2 mode of TM01 based on small-signal theory,and under the same energy storage,the maximum electric field in extractor decreases 16.3%.Besides,by utilizing the natural bending of the solenoid,this TTO saves over 60%of the length required by the uniform magnetic field,and consequently reduces the energy consumed by solenoid.The PIC simulation shows that by using 1.0-T decreasing magnetic field generated by the shorter solenoid,3.37-GW microwave at 12.43 GHz is generated with 620-kV and 13.27-kA input,and the overall conversion efficiency is 41%.

Role of color Doppler flow imaging in applicable anatomy of spleen vessels

AIM： To explore the role of color Doppler flow imaging （CDFI） in visualization of spleen vessels and to define its value for spleen micro-invasive operation. METHODS： A total of 36 patients requiring laparoscopic splenectomy （LS） for various hematopathies and autoimmune diseases were randomly selected from April 2005 to May 2008. Anatomic types of spleen pedicle, adjacent relations between spleen vessels and pancreas, diameters of spleen artery and vein were detected and recorded by preoperative CDFI. Different operative procedures were performed according to different anatomic frameworks. The parameters were recorded by telerecording during LS and compared with those by preoperative CDFI using Chi-square test. RESULTS： Two anatomic types of spleen pedicle and four different adjacent relations between spleen vessels and pancreas were detected by CDFI. The diameters of spleen artery and vein detected by CDFI were 0.46 ± 0.09 cm and 0.85 ± 0.35 cm, respectively. There was no statistical difference between the parameters recorded by CDFI and by telerecording （X^2 = 0.250, 0.677, P 〉 0.05）. LS was successfully performed following the anatomic information provided by preoperative CDFI.CONCLUSION： Different anatomic frameworks of spleen vessels can be provided by preoperative CDFI, which instructs micro-invasive operation of spleen and increase the safety of operation.

Targeted inhibition of myeloid-derived suppressor cells in the tumor microenvironment by low-dose doxorubicin to improve immune efficacy in murine neuroblastoma

Background:High agglomeration of myeloid-derived suppressor cells(MDSCs)in neuroblastoma(NB)impeded therapeutic effects.This study aimed to investigate the role and mechanism of targeted inhibition of MDSCs by low-dose doxorubicin(DOX)to enhance immune efficacy in NB.Methods:Bagg albino(BALB/c)mice were used as tumor-bearing mouse models by injecting Neuro-2a cells,and MDSCs were eliminated by DOX or dopamine(DA)administration.Tumor-bearing mice were randomly divided into 2.5 mg/kg DOX,5.0 mg/kg DOX,50.0 mg/kg DA,and control groups(n=20).The optimal drug and its concentration for MDSC inhibition were selected according to tumor inhibition.NB antigen-specific cytotoxic T cells(CTLs)were prepared.Tumor-bearing mice were randomly divided into DOX,CTL,anti-ganglioside(GD2),DOX+CTL,DOX+anti-GD2,and control groups.Following low-dose DOX administration,immunotherapy was applied.The levels of human leukocyte antigen(HLA)-I,CD8,interleukin(IL)-2 and interferon(IFN)-γin peripheral blood,CTLs,T-helper 1(Th1)/Th2 cytokines,perforin,granzyme and tumor growth were compared among the groups.The Wilcoxon two-sample test and repeated-measures analysis of variance were used to analyze results.Results:The slowest tumor growth(F=6.095,P=0.018)and strongest MDSC inhibition(F=14.632,P=0.001)were observed in 2.5 mg/kg DOX group.Proliferation of T cells was increased(F=448.721,P<0.001)and then decreased(F=2.047,P=0.186).After low-dose DOX administration,HLA-I(F=222.489),CD8(F=271.686),Th1/Th2 cytokines,CD4^(+)and CD8^(+)lymphocytes,granzyme(F=2376.475)and perforin(F=488.531)in tumor,IL-2(F=62.951)and IFN-γ(F=240.709)in peripheral blood of each immunotherapy group were all higher compared with the control group(all ofP values<0.05).The most significant increases in the aforementioned indexes and the most notable tumor growth inhibition were observed in DOX+anti-GD2 and DOX+CTL groups.Conclusions:Low-dose DOX can be used as a potent immunomodulatory agent that selectively impairs MDSC-induced immunosuppression,thereby fostering immune efficacy in NB.