2,454 research outputs found
Novel Compact Three-Way Filtering Power Divider Using Net-Type Resonators
In this paper, we present a novel compact three-way power divider with bandpass responses. The proposed power divider utilizes folded net-type resonators to realize dual functions of filtering and power splitting as well as compact size. Equal power ratio with low magnitude imbalance is achieved due to the highly symmetric structure. For demonstration, an experimental three way filtering power divider is implemented. Good filtering and power division characteristics are observed in the measured results of the circuit. The area of the circuits is 14.5 mm x 21.9 mm or 0.16 λg x 0.24 λg, where the λg is the guide wavelength of the center frequency at 2.1 GHz
Anti-depressant-like effect of curculigoside isolated from Curculigo orchioides Gaertn root
Purpose: To investigate the anti-depressant-like activity of curculigoside from Curculigo orchioides Gaertn and its underlying mechanism(s).Methods: Antidepressant-like activity was determined in mice through forced swimming test (FST), tail suspending test (TST), and open field test (OFT). Mechanism of action was investigated by measuring levels of dopamine (DA), norepinephrine (NE), and 5-hydroxytryptamine (5-HT) in chronic mild stress (CMS) rats using high-performance liquid chromatography-electron capture detector (HPLC-ECD). Western blotting was used to investigate the effect of curculigoside on the expression of brain-derived neurotrophic factor (BDNF) protein in rats.Results: In FST and TST, treatment of mice with curculigoside (10, 20, 40 mg/kg, p.o.) significantly reduced immobility time, which was, however, unaffected by locomotor activity when assessed in the OFT. The treatment led to significant increases in DA, NE and 5-HT, and up-regulation of BDNF protein expression in the hippocampus of the CMS rats.Conclusion: These results demonstrate that curculigoside exerts significant anti-depressant-like activity on mice, the mechanism of which involves increase in the levels of DA, NE, 5-HT, and up-regulation of BDNF expression. Thus, curculigoside can be considered a potential drug candidate for the treatment of depressive disorders.Keywords: Curculigo orchioides Gaertn, Curculigoside, Antidepressant-like activity, Behavioral studie
Non-traditional CD4+CD25−CD69+ regulatory T cells are correlated to leukemia relapse after allogeneic hematopoietic stem cell transplantation
Background: Non-traditional CD4+CD25-CD69+ T cells were found to be involved in disease progression in tumor-bearing mouse models and cancer patients recently. We attempted to define whether this subset of T cells were related to leukemia relapse after allogeneic hematopoietic cell transplantation (allo-HSCT). Methods: The frequency of CD4+CD25-CD69+ T cells among the CD4+ T cell population from the bone marrow of relapsed patients, patients with positive minimal residual disease (MRD+) and healthy donors was examined by flow cytometry. The CD4+CD25-CD69+ T cells were also stained with the intracellular markers to determine the cytokine (TGF-beta, IL-2 and IL-10) secretion. Results: The results showed that the frequency of CD4+CD25-CD69 + T cells was markedly increased in patients in the relapsed group and the MRD + group compared to the healthy donor group. The percentage of this subset of T cells was significantly decreased after effective intervention treatment. We also analyzed the reconstitution of CD4+CD25-CD69+ T cells at various time points after allo-HSCT, and the results showed that this subset of T cells reconstituted rapidly and reached a relatively higher level at +60 d in patients compared to controls. The incidence of either MRD+ or relapse in patients with a high frequency of CD4+CD25-CD69+ T cells (>7%) was significantly higher than that of patients with a low frequency of CD4+CD25-CD69+ T cells at +60 d, +90 d and +270 d after transplant. However, our preliminary data indicated that CD4+CD25-CD69+ T cells may not exert immunoregulatory function via cytokine secretion. Conclusions: This study provides the first clinical evidence of a correlation between non-traditional CD4+CD25-CD69+ Tregs and leukemia relapse after allo-HSCT and suggests that exploration of new methods of adoptive immunotherapy may be beneficial. Further research related to regulatory mechanism behind this phenomenon would be necessary.Medicine, Research & ExperimentalSCI(E)[email protected]
Coordinated Damping Control Design for Power System With Multiple Virtual Synchronous Generators Based on Prony Method
With more renewables integrated into power grids, the systems are being transformed into low inertia power electronic dominated systems. In this situation, the virtual synchronous generator (VSG) control strategy was proposed to deal with insufficient inertia challenge caused by the reduction of synchronous generation. However, as the VSG control method emulates the dynamic behavior of traditional synchronous machines, the interaction between multiple VSG controllers and synchronous generators (SGs) may cause low-frequency oscillation similar to that caused by the interaction between multiple SGs. This paper reveals that the system low-frequency oscillatory modes are affected by multiple VSGs. Then Prony analysis is utilized to extract the system mode information which will be subsequently used for VSG controller design, and a decentralized sequential coordinated method is proposed to design the supplementary damping controller (SDC) for multiple VSGs. The system low-frequency oscillation is first analyzed based on a modified two-area system with a linearized state-space model, and a further case study based on a revised New England 10-machine 39-bus system is used to demonstrate the effectiveness of the proposed coordinated method for multiple VSGs
Methyl 3-methyl-5-oxo-4-(phenylhydrazono)-4,5-dihydro-1H-pyrazole-1-carbodithioate
The title compound, C12H11N4OS2, has been synthesized by the condensation reaction of 3-oxo-2-(phenylhydrazono)butanate and S-methyldithiocarbazate. The hydrazine unit and the pyrazole ring are coplanar [dihedral angle 3.8 (4)°] due to extensive conjugation and the N—H⋯O=C intramolecular hydrogen bond. Two adjacent molecules form dimers due to short C—H⋯O=C [R
2
2 (18)] and C—H⋯S=C [R
2
2 (22)] intermolecular interactions. C—H⋯S—C [R
2
2 (14)] interactions link these dimers into ribbons in the [011] direction
Dual-Band Patch Antenna Fed by Meandering Probe for Low Cross-Polarization
This paper presents a dual-band patch antenna loaded with face-to-face U-shaped slots fed by a substrate-integrated meandering probe (SIM-probe). With the presence of U-shaped slots, two current paths are formed, which leads to the resonance modes at 2.4 and 3.65 GHz on the patch. The SIM-probe suppresses the unwanted cross-polarization radiations by providing out-of-phase vertical currents from vertical metallic vias. To verify our work, a prototype was fabricated and tested. The proposed antenna achieves the impedance bandwidths of 9.4% and 9% from the frequency range of 2.34–2.57 GHz and 3.5–3.83 GHz (for the reflection coefficient ≤ −10 dB) and obtains average gains of 5.8 dBi and 6.8 dBi at both bands. The cross-polarization level is below −20 dB. Measured results agree well with the simulation
A High-Quality Mach-Zehnder Interferometer Fiber Sensor by Femtosecond Laser One-Step Processing
During new fiber sensor development experiments, an easy-to-fabricate simple sensing structure with a trench and partially ablated fiber core is fabricated by using an 800 nm 35 fs 1 kHz laser. It is demonstrated that the structure forms a Mach-Zehnder interferometer (MZI) with the interference between the laser light passing through the air in the trench cavity and that in the remained fiber core. The fringe visibilities are all more than 25 dB. The transmission spectra vary with the femtosecond (fs) laser ablation scanning cycle. The free spectral range (FSR) decreases as the trench length increases. The MZI structure is of very high fabrication and sensing repeatability. The sensing mechanism is theoretically discussed, which is in agreement with experiments. The test sensitivity for acetone vapor is about 104 nm/RIU, and the temperature sensitivity is 51.5 pm/°C at 200 ~ 875 °C with a step of 25 °C
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