Exploration of drug resistance mechanisms in triple negative breast cancer cells using a microfluidic device and patient tissues.

Chemoresistance is a major cause of treatment failure in many cancers. However, the life cycle of cancer cells as they respond to and survive environmental and therapeutic stress is understudied. In this study, we utilized a microfluidic device to induce the development of doxorubicin-resistant (DOXR) cells from triple negative breast cancer (TNBC) cells within 11 days by generating gradients of DOX and medium. In vivo chemoresistant xenograft models, an unbiased genome-wide transcriptome analysis, and a patient data/tissue analysis all showed that chemoresistance arose from failed epigenetic control of the nuclear protein-1 (NUPR1)/histone deacetylase 11 (HDAC11) axis, and high NUPR1 expression correlated with poor clinical outcomes. These results suggest that the chip can rapidly induce resistant cells that increase tumor heterogeneity and chemoresistance, highlighting the need for further studies on the epigenetic control of the NUPR1/HDAC11 axis in TNBC.

Development of a high-power pulse-forming network Marx generator with a long pulse duration.

To meet the application needs for producing long-pulse electron beams and high-power microwaves, a pulse-forming network Marx generator with a pulse duration of 260 ns is presented in this paper. This generator is composed of 20 stages of pulse-forming network modules. Each module is formed with nine capacitors connected in parallel. The generator functions at 44 kV, which is lower than the rated voltage of the mica paper capacitor, to improve the lifetime. The impedance of the generator is designed to reach 45 Ω. To avoid the strong coupling between the adjacent stages, the physical layout of the generator adopts a zigzag design. The generator is housed in a gas pressurized vessel of 600 mm in diameter and 580 mm in length. Across a 50 Ω load, it can deliver quasi-rectangular pulses with a pulse duration of 260 ns and an amplitude of 500 kV for a single shot. The output pulse features a plateau duration of 160 ns and a leading edge of 45 ns. In burst mode, it can steadily output ten pulses of 450 kV at a repetition rate of 10 Hz on either a resistive load or a diode.

A compact repetitive high energy-density accelerator HEART-20 based on propylene carbonate pulse forming line.

The development of pulsed power technology requires an electron beam accelerator with high output power and repetitive operation. A compact repetitive electron beam accelerator based on a pulse transformer and a pulse forming line of high permittivity liquid, as an essential type of one, has attracted extensive attention at the present time. In this paper, the development of a compact high energy-density electron beam accelerator, viz., HEART-20, based on a propylene carbonate (PC) forming line is presented. The accelerator HEART-20 consists of a primary energy source, a pulse transformer, a PC pulse forming line, a gas spark gap switch, and a vacuum diode. First, the operation principle of the accelerator is described. Second, the design of the accelerator's parameters is presented. A pulse transformer is developed for rapid charging of the PC-filled pulse forming line. The coupling coefficient is above 0.9, the voltage ratio is about 200, and the operation voltage is about 800 kV. Third, the energy storage characteristics of PC are investigated. The insulation characteristics of PC under positive charging voltage are found to perform better than those under negative charging voltage. The insulating strength of PC can be improved by pressurization. Finally, the development of the accelerator HEART-20 is presented. Across a vacuum diode load, it can steadily operate at a 20 GW output power in 5 Hz rep-rate. Moreover, it can drive a magnetically insulated line oscillator to produce about 2.0 GW microwave. These findings provide a good foundation for the development of a rep-rate intensive electron beam accelerator with promising applications for the future.

Design and experimental demonstration of a beam scanning lens antenna.

A beam scanning antenna based on an all-metal lens is presented for high-power microwave (HPM) application in this paper. This design includes a feed antenna and two layers of different all-metal lenses, whose prototypes operating at 14.25 GHz have been successfully designed and fabricated with an aperture radius of 300 mm. A full transmission phase range of 360° can be achieved with a transmission efficiency of over 99% by rotating the cross-slot on the lens elements. The results of the low-power tests depict that the designed antenna can realize a beam scanning range of 120° revolving cone angle with the side lobe below -10 dB and the reflection coefficient less than -16 dB. The high-power tests demonstrate that the power handling capacity of the antenna is higher than 350 MW in sulfur hexafluoride (SF6). In addition, both the designed lenses have a bandwidth of more than 100 MHz. All the merits show that our designed all-metal lens antenna has a great potential to be applied in HPM systems.

A dielectric embedded reflectarray for high-power microwave application.

To solve the problem of the large axial size of high-power microwave (HPM) reflectarray antenna and difficulty in vacuum packaging, a dielectric is introduced in the design of the antenna element. On this basis, a dielectric embedded metasurface reflectarray antenna (DEMRA) with high power handling capacity and wide-range beam scanning capability is proposed and fabricated. Compared with traditional HPM antennas, the DEMRA does not need to be sealed and can work directly in open-air conditions. The DEMRA can realize free regulation of the radiation beam within a cone angle of 90° and has a power handling capacity of 1 GW/m2. As verification, a protype working at 10 GHz is fabricated and low-power experiments are carried out. Experimental results are consistent with the simulation, proving that the DEMRA has a bandwidth exceeding 600 MHz. During the scanning process, the aperture efficiency is always higher than 48.98%, and the side lobe level remains below -15 dB. At the same time, the cross-polarization component is less than -15 dB, while the main lobe-axis ratio remains within 4.5 dB, confirming its beam scanning capability.

Low-impedance high-power pulsed generator based on forming line with built-in Tesla transformer.

In order to meet the application needs of gyromagnetic nonlinear transmission lines, a pulsed power generator is required to output short duration pulses with a fast rising edge in high repetitive-rate mode. In this paper, a low-impedance high-power pulsed generator based on the forming line with a built-in Tesla transformer is explored and developed. The generator includes a 14 Ω coaxial forming line, a SF6/N2 gas switch, and a resistive dummy load, which can steadily operate in 100 Hz mode and suits the needs above. The pulsed forming line adopts transformer oil as the insulation medium and has a large shell radius and short length to reduce impedance. It has been verified by CST simulation that a relatively high coupling coefficient (0.93) can be achieved when the length-radius ratio is 3.2. The maximum forming line charging voltage is -600 kV in single-shot mode, while the charging voltage is -520 kV in repetitive-rate mode. The output pulse duration is 13 ns with a 4 ns rising edge, and its amplitude for a 10 Ω load is -220 kV at a repetition rate of 100 Hz. The experimental results showed the feasibility of the low-impedance nanosecond periodically pulsed generator based on an oil forming line charged from the high-coupling Tesla transformer. These efforts expand the technical route of the pulse forming line with a built-in Tesla transformer and set a good foundation for its application in the future.

Multi-population cooperative evolution-based image segmentation algorithm for complex helical surface image.

Accurate image segmentation results would show a great significance to computer vision-based manufacturing for complex helical surface. However, the image segmentation for complex helical surface is always a difficult problem because of the uneven gray distribution and non-homogeneous feature patterns of its images. Therefore, a multi-direction evolutionary segmentation model is constructed and a multi-population cooperative evolution algorithm is proposed to solve the new model. According to the characteristics of gray distribution and feature patterns of complex helical surface image, an eigenvector extraction and description strategy is researched by combining gray level co-occurrence matrix algorithm with fractal algorithm, and the complex helical surface image can be described succinctly by gray feature and shape feature. Based on the description algorithm of image features, an image segmentation strategy using cooperative evolution from different eigenvector is discussed, and the helical surface image segmentation is decomposed from a single objective optimization problem to a multi-objective optimization problem to improve the accuracy of segmentation. Meanwhile, a multi-objective particle swarm optimization algorithm based on multi-directional evolution and shared archives is presented. Due to the fact that each eigenvector segmentation corresponds to one evolution direction, the collaboration of local and global segmentation can be realized by information sharing and interaction between evolution directions and the archive set. The comprehensive quality of non-dominated solution can be improved by the selection strategy of local and global optimal solution as well as the archive set maintenance. The practical numerical experiments for complex helical surface image segmentation are carried out to prove the validity of the proposed model and algorithm.

High-power waveguide phase shifters for phased array applications.

Two kinds of high-power waveguide phase shifters targeting the application of phased arrays are proposed in this paper. To enhance the power handling capacity, both linear phase shifters are designed to be mechanically tunable without the introduction of a dielectric and a semiconductor. For the waveguide-inserting-fin phase shifter, the phase shifting function is achieved by adjusting the length of the inserting metal fin. As for the narrow-side slot-waveguide phase shifter, the regulation of the position of the metal choke plunger placed at the end of the 3-dB power divider is used to adjust the output phase. The simulation results show that both phase shifters can realize 2π phase shift, and the transmission efficiencies are over 99% at the central frequency of 9.5 GHz. Meantime, the power handling capacity of the designed shifters is expected to be over 100 MW, which can be applied in the high-power microwave region. The slot-waveguide phase shifter is fabricated and tested along with the slotted array antenna. The experimental results coincide well with the simulations, which demonstrates the feasibility and the power capacity of the designed shifter.

Compact circular polarizer based on cross-shaped slot for high-power microwave applications.

A compact high-power waveguide circular polarizer working at the C-band is presented in this paper. By introducing a split-ring slot and an orthogonally crossed rectangular slot into a circular waveguide, high transmission efficiency and 90° phase difference of two linearly polarized orthogonal TE11 modes are achieved by using the polarizer within a half wavelength. In the meantime, the power handling capacity of the designed polarizer is expected to be over 120 MW, which can be applied in the high-power microwave region. The designed circular polarizer is fabricated and measured by the cold test; the results of experiments and simulations agree well with each other. It is shown in the experiments that the axial ratio is less than 0.9 dB, the voltage standing-wave ratio is less than 1.2, and the conversion efficiency is over -0.15 dB at 4.2-4.4 GHz.

Self-marked HCN gas based FBG demodulation in thermal cycling process for aerospace environment.

The thermal cycling process experienced by spacecraft during orbital operation would lead to deterioration of the demodulation performance of fiber Bragg grating (FBG). A new demodulation method based on Fabry-Perot (F-P) filter and hydrogen cyanide (HCN) gas is proposed to improve the performance. The method skillfully utilizes the self-marked HCN absorption lines as absolute wavelength references. In the thermal cycling environment whose temperature ranging from 5°Cto 65°C,the fluctuation of demodulation wavelength reduces to ± 2.6 pm, which is improved by 3.1 times compared with traditional method. The proposed method also shows a good robustness in the cases of weak light source intensity and poor signal-to-noise ratio (SNR) of HCN spectrum.

Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier.

The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs.

Effect of BaTiO3 nano-particles on breakdown performance of propylene carbonate.

As an alternative to water, propylene carbonate (PC) has a good application prospect in the compact pulsed power sources for its breakdown strength higher than that of water, resistivity bigger than 10(9) Ω m, and low freezing temperature (-49 °C). In this paper, the investigation into dielectric breakdown of PC and PC-based nano-fluids (NFs) subjected to high amplitude electric field is presented with microsecond pulses applied to a 1 mm gap full of PC or NFs between spherical electrodes. One kind of NF is composed of PC mixed with 0.5-1.4 vol. % BaTiO3 (BT) nano-particles of mean diameter ≈100 nm and another is mixed with 0.3-0.8 vol. % BT nano-particles of mean diameter ≈30 nm. The experimental results demonstrate the rise of permittivity and improvement of the breakdown strength of NFs compared with PC. Moreover, it is found that there exists an optimum fraction for these NFs corresponding to tremendous surface area in nano-composites with finite mesoscopic thickness. In concrete, the dielectric breakdown voltage of NFs is 33% higher than that of PC as the volume concentration of nano-particles with a 100 nm diameter is 0.9% and the breakdown voltage of NFs is 40% higher as the volume concentration of nano-particles with a 30 nm diameter is 0.6%. These phenomena are considered as the dielectric breakdown voltage of PC-based NFs is increased because the interfaces between nano-fillers and PC matrices provide myriad trap sites for charge carriers, which play a dominant role in the breakdown performance of NFs.

Study on a discal TEM-TE11 mode converter loaded high-efficiency magnetically insulated transmission line oscillator.

An integrative high power microwave device is proposed, which consists of a high-efficiency L-band Magnetically Insulated Transmission Line Oscillator (MILO) and a discal TEM-TE11 mode converter. The MILO with a shrunken load composed of a step-like cathode and a ladder-like beam collector can generate a 1.58 GHz, 5.7 GW microwave with the efficiency of 20.8% at the diode voltage of 560 kV in simulation. The discal converter utilizes a pair of sectorial two-double radial waveguides and a pair of sectorial cross section waveguides to adjust the phase-difference and realizes the mode conversion in a length of less than half wavelength at 1.58 GHz. In the preliminary experiment, the proposed device generates over 2 GW, 1.575 GHz microwave with the pulse duration of over 50 ns in a 420 kV diode voltage; the corresponding efficiency is 14.9%; the radiation pattern is the ideal TE11 mode.

Slightly uneven electric field trigatron employed in tens of microseconds charging time.

To solve the issue of operation instability for the trigatron switch in the application of tens of microseconds or even less charging time, a novel trigatron spark gap with slightly uneven electric field was presented. Compared with the conventional trigatron, the novel trigatron was constructed with an obvious field enhancement on the edge of the opposite electrode. The selection of the field enhancement was analyzed based on the theory introduced by Martin. A low voltage trigatron model was constructed and tested on the tens of microseconds charging time platform. The results show that the character of relative range was improved while the trigger character still held a high level. This slightly uneven electric field typed trigatron is willing to be employed in the Tesla transformer - pulse forming line system.

Focusing electrode and coaxial reflector used for reducing the guiding magnetic field of the Ku-band foilless transit-time oscillator.

Based on the theoretical analysis of the intense relativistic electron beam propagation in the coaxial drift-tube, a focusing electrode and a coaxial reflector is proposed to lessen the demand of the coaxial Ku-band foilless transit-time oscillator (TTO) for the guiding magnetic field. Moreover, a Ku-band TTO with the focusing electrode and the coaxial reflector is designed and studied by particle in cell simulation. When the diode voltage is 390 kV, the beam current 7.8 kA, and the guiding magnetic field is only 0.3 T, the device can output 820 MW microwave pulse at 14.25 GHz by means of the simulation. However, for the device without them, the output power is only 320 MW. The primary experiments are also carried out. When the guiding magnetic field is 0.3 T, the output power of the device with the focusing electrode and the coaxial reflector is double that of the one without them. The simulation and experimental results prove that the focusing electrode and the coaxial reflector are effective on reducing the guiding magnetic field of the device.

Jitter characteristic of series magnetic pulse compressor employed in ns trigger generator.

The jitter characteristic of series magnetic pulse compressor (MPC) employed in ns trigger generator was explored. The time delay of the series MPC is the sum value of the compression time in each stage. The primary voltage disturbance is the original parameter to affect the timing stability of the system. Decreasing the relative jitter of the primary voltage and the first compression time are the practical and exclusive approaches to decrease to time jitter of the series MPC. The jitter experiment was carried out on the three-stage series MPC charged with a fast step-up LC transformer. The performance data show that the delay time decreases with the increase of primary voltage. Meanwhile, the measured ratio between the time jitter and the relative jitter of the primary voltage accords with the theoretical result.

A long-pulse repetitive operation magnetically insulated transmission line oscillator.

The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

An all solid-state high-voltage ns trigger generator based on magnetic pulse compression and transmission line transformer.

Innovative design of an all solid-state high-voltage ns trigger generator, based on magnetic pulse compression and transmission line transformer, is presented. The repetitive trigger pulse generator was developed to trigger a 700 kV trigatron, which has been used to pulse a repetitive intense electron beam accelerator with Tesla transformer charged double pulse forming lines (PFLs). Experimental results show that the trigger pulse generator could produce 180 kV 65 ns duration pulses with a rise time of 20 ns. The repetitive trigger pulses have nice uniform in the voltage waveform. The control time jitter is less then 3 ns. Owing to its good stability and low time jitter, the high-voltage trigger generator is an excellent candidate to trigger the repetitive accelerator.

Investigation of a compact coaxially fed switched oscillator.

To generate a relative high frequency mesoband microwave, a compact coaxially fed transmission line switched oscillator with high voltage capability is investigated. The characteristic impedance and voltage capability of the low impedance transmission line (LITL) have been analyzed. It is shown that the working voltage of the oscillator can reach up to 200 kV when it is filled by pressurized nitrogen and charged by a nanosecond driving source. By utilizing a commercial electromagnetic simulation code, the transient performance of the switched oscillator with a lumped resistance load is simulated. It is illustrated that the center frequency of the output signal reaches up to ~0.6 GHz when the spark gap practically closes with a single channel. Besides, the influence of the closing mode and rapidity of the spark gap, the permittivity of the insulator at the output end of the LITL, and the load impedance on the transient performance of the designed oscillator has been analyzed in quantification. Finally, the good transient performance of the switched oscillator has been preliminarily proved by the experiment.

Fast modeling of flux trapping cascaded explosively driven magnetic flux compression generators.

To predict the performance of flux trapping cascaded flux compression generators, a calculation model based on an equivalent circuit is investigated. The system circuit is analyzed according to its operation characteristics in different steps. Flux conservation coefficients are added to the driving terms of circuit differential equations to account for intrinsic flux losses. To calculate the currents in the circuit by solving the circuit equations, a simple zero-dimensional model is used to calculate the time-varying inductance and dc resistance of the generator. Then a fast computer code is programmed based on this calculation model. As an example, a two-staged flux trapping generator is simulated by using this computer code. Good agreements are achieved by comparing the simulation results with the measurements. Furthermore, it is obvious that this fast calculation model can be easily applied to predict performances of other flux trapping cascaded flux compression generators with complex structures such as conical stator or conical armature sections and so on for design purpose.