Visualization of Photonic Band Structures via Far-field Measurements in SiNx Photonic Crystal Slabs

The band structures of the photonic crystal slabs play a significant role in manipulating the flow of light and pre-dicting exotic physics in photonics. In this letter, we show that the key features of photonic band structures can be achieved experimentally by the polarization- and momentum-resolved photoluminescence spectroscopy utilizing the light emission properties of SiNx. The two-dimensional spectra clearly reveal the energy-momentum dispersion of band structures which is in perfect agreement with the simulation results. The isofrequency contours can be measured easily by adding a bandpass filter with a desired photon energy. Furthermore, it is convenient to observe clearly and directly the optical singularity -- the optical bound states in the continuum featured by dark point in three-dimensional photoluminescence spectra. The polarization-resolved isofrequency contours clearly show that this dark point is the center of an azimuthally polarized vortex. Finally, the helical topological edge states can be easily observed in photonic topological insulators with deformed hexagonal lattices. Our work provides a simple and effective approach for exploring topological photonics and other intriguing phenomena hidden in the photonic crystal slabs.Comment: 6 pages, 5 figure

Tunable microwave dielectric properties in SrO‐V2O5 system through compositional modulation

Adjustment on resonance frequency stability against the sintering temperature of Sr3V2O8 was realized by adjusting the Sr:V mole ratio. Effects of Sr:V ratio on sintering behavior and dielectric properties of Sr3V2O8 were studied. The sintering temperature was sucessfully reduced to 950°C from 1150°C. With increasing vanadium content, both relative permittivity and quality factor decreased, while the temperature coefficient of resonance frequency shifted from positive to negative values. Especially, a near‐zero τf of −1.1 ppm/°C along with a low permittivity (εr) of 9.8 and a quality factor Q × f of 24 120 GHz was successfully achieved in Sr3‐yV2O8‐y ceramic (y = 0.6, sintered at 950°C). The wide compositional and processing adjustment window, favorable dielectric performances, and good chemical compatibility with silver render Sr3‐yV2O8‐y ceramics potential candidates in multilayer electronic devices

Synthesis of LiBGeO4 using compositional design and its dielectric behaviors at RF and microwave frequencies

Borates are promising candidates as dielectric substrate materials in low temperature cofired ceramics technology (LTCC) due to their relative low sintering temperatures and relative permittivities compared to their counterparts. However, synthesizing borates having single-phase is still challenging because of the volatility and hydrophilicity of boron resources. In this work, a compositional design was utilized to synthesize single-phase LiBGeO 4 ceramics over a broad temperature range from 600 to 840 °C. Radio-frequency dielectric behaviours featured a strong temperature dependence, especially at high temperatures (>400 °C), which is related to the thermally activated polarizations. LiBGeO 4 ceramic sintered at 820 °C has optimum microwave dielectric properties with the relative permittivity (ε r) of 6.28, a quality factor (Q × f) of 21,620 GHz, and a temperature coefficient of resonance frequency (τ f) of -88.7 ppm/ °C. LiBGeO 4 also showed chemical inertness when cofired with silver (Ag), provided an evidence for its utilization in LTCC technology. Overall, this work provides a strategy for facile synthesis of phase pure borates, via the proposed two-step process to obtain stable boron resources

The Stimulation of IGF-1R Expression by Lewis(y) Antigen Provides a Powerful Development Mechanism of Epithelial Ovarian Carcinoma

Objective: This study aimed to measure and correlate the expression of insulin-like growth factor receptor-1 (IGF-1R) and the Lewis(y) antigen in ovarian cancer cell lines and tissue samples. Methods: Reverse transcriptase PCR (RT-PCR), Western blotting, immunoprecipitation, immunohistochemistry, and immunofluorescence double-labeling techniques were applied to detect and measure the expression of Lewis(y) and IGF-1R. Results: In α1,2-fucosyltransferase (α1,2-FT)-transfected cells, IGF-1R expression was significantly upregulated compared with cells that do not overexpress α1,2-FT (P < 0.05). The amount of Lewis(y) expressed on IGF-1R increased 1.81-fold in α1,2-FT-overexpressing cells (P < 0.05), but the ratio of Lewis(y) expressed on IGF-1R to total IGF-1R was unaltered between two cells (P > 0.05). In malignant epithelial ovarian tumors, the positivity rates of Lewis(y) and IGF-1R detection were 88.3% and 93.33%, respectively, which is higher than the positivity rates in marginal (60.00% and 63.33%, all P < 0.05), benign (33.00% and 53.33%, all P < 0.01), and normal (0% and 40%, all P 0.05). Both IGF-1R and Lewis(y) were highly expressed in ovarian cancer tissues, and their expression levels were positively correlated (P < 0.05). Conclusion: Overexpression of Lewis(y) results in overexpression of IGF-1R. Both IGF-1R and Lewis(y) are associated with the occurrence and development of ovarian cancers

Study on the Expression and Clinical Significances of Lewis y Antigen and Integrin αv, β3 in Epithelial Ovarian Tumors

Objective: To detect the expression and clinical significances of Lewis y antigen and integrin αv, β3 in epithelial ovarian tumors, and to explore the expression correlation between Lewis y antigen and integrin αv, β3. Methods: Immunohistochemical staining was performed in 95 cases of epithelial ovarian cancer, 37 cases of borderline tumors, 20 cases of benign tumors, and 20 cases of normal ovarian tissue, for the detection of Lewis y antigen and integrin αv, β3 expressions, and to analyze the relationship between Lewis y antigen and integrin, and the relationship between clinical and pathological parameters of ovarian cancer. In addition, immunofluorescence double labeling was utilized to detect the expression correlation between Lewis y antigen and integrin αv, β3 in ovarian cancer. Results: In epithelial ovarian tumors, the expression rate of Lewis y antigen was 81.05%, significantly higher than that of borderline (51.53%) (P < 0.05) and benign (25%) (P < 0.01) tumors, and normal ovarian tissues (0) (P < 0.01). The expression rate of integrin αv, β3 in malignant epithelial ovarian tumors was 78.95% and 82.11%, respectively, significantly higher than that of the borderline (45.94%, 40.54%) (both P < 0.05), benign group (10.00%, 15.00%) (both P < 0.01) and normal ovary group (5%, 15%) (both P < 0.01). Conclusions: Lewis y and integrins αv, β3 are relevant to pelvic and abdominal diffusion and metastasis of ovarian cancer cells, suggesting that these two molecules mediate a boosting function for tumor metastasis

Electrical Conductivity Studies on Individual Conjugated Polymer Nanowires: Two-Probe and Four-Probe Results

<p>Abstract</p> <p>Two- and four-probe electrical measurements on individual conjugated polymer nanowires with different diameters ranging from 20 to 190 nm have been performed to study their conductivity and nanocontact resistance. The two-probe results reveal that all the measured polymer nanowires with different diameters are semiconducting. However, the four-probe results show that the measured polymer nanowires with diameters of 190, 95&#8211;100, 35&#8211;40 and 20&#8211;25 nm are lying in the insulating, critical, metallic and insulting regimes of metal&#8211;insulator transition, respectively. The 35&#8211;40 nm nanowire displays a metal&#8211;insulator transition at around 35 K. In addition, it was found that the nanocontact resistance is in the magnitude of 10⁴&#937; at room temperature, which is comparable to the intrinsic resistance of the nanowires. These results demonstrate that four-probe electrical measurement is necessary to explore the intrinsic electronic transport properties of isolated nanowires, especially in the case of metallic nanowires, because the metallic nature of the measured nanowires may be coved by the nanocontact resistance that cannot be excluded by a two-probe technique.</p

Ultralow-Temperature Synthesis and Densification of Ag2CaV4O12 with Improved Microwave Dielectric Performances

At extremely low temperatures, Ag2CaV4O12 was easily synthesized using the traditional solid-state approach. With a low relative permittivity (εr) of 7.52, a high quality factor (Q × f) of 48 800 GHz (f = 13.6 GHz), and a temperature coefficient of resonance frequency (τf) of −77.4 ppm/°C, dense ceramics sintered at 480 °C with outstanding microwave dielectric characteristics were attained. By combining with rutile TiO2, a composite ceramic with balanced microwave dielectric properties (τf = 3.2 ppm/°C, εr = 10.96, and Q × f = 49 081 GHz) was achieved. No chemical reaction between Ag2CaV4O12 and silver and aluminum occurred. All of the findings show that Ag2CaV4O12 has the potential to be used as dielectric resonances in wireless communication and as substrates in low-temperature cofired ceramics. Furthermore, the processing at an ultralow temperature of Ag2CaV4O12 shows that it is extraordinarily energy saving from the point of view of fabrication and might allow for room-temperature synthesis by combining with high-energy mechanical milling or sintering using a high pressure such as hot isostatic pressing (HIP), spark plasma sintering (SPS), and cold sintering (CS)

Current treatment of tracheoesophageal fistula

Tracheoesophageal fistulas (TEFs) often occur with esophageal or bronchial carcinoma. Currently, we rely on implantation of delicate devices, such as self-expanding and silicone stents, in the esophagus or trachea to cover the fistula and expand the stenosis in order to relieve patient pain. However, because each case is different, our approach may not be effective for every patient. Consequently, new devices and technology have emerged to address these situations, such as degradable stents, Amplatzer ® devices, endobronchial one-way umbrella-shaped valves, and transplantation of mesenchymal stem cells. Although some studies have shown such alternatives can be reasonable solutions in special cases, further development of other new and effectual techniques is of utmost importance

Analysis of Anomalous Enhancement in TEC and Electron Density in the China Region Prior to the 17 March 2015 Geomagnetic Storm Based on Ground and Space Observations

Total Electron Content (TEC) and electron density enhancement were observed on the day before 17 March 2015 great storm in the China Region. Observations from ground- and space-based instruments are used to investigate the temporal and spatial evolution of the pre-storm enhancement. TEC enhancement was observed from 24°N to 30°N after 10:00 UT at 105°E, 110°E and 115°E longitudes on March 16. The maximum magnitude of TEC enhancement was more than 10 TECU and the maximal relative TEC enhancement exceeded 30%. Compared with geomagnetic quiet days, the electron density of Equatorial Ionization Anomaly (EIA) northern peak from Swarm A/C satellites on March 16 was larger and at higher latitudes. NmF2 enhanced during 11:30—21:00 UT at Shaoyang Station and increased by 200% at ~16:00 UT. However, TEC and electron density enhancement were not accompanied by a significant change of hmF2. Most research has excluded some potential mechanisms as the main driving factors for storm-time density enhancements by establishing observational constraints. In this paper, we observed pre-storm enhancement in electron density at different altitudes and Equatorial Electrojet (EEJ) strength results derived from ground magnetometers observations suggest an enhanced eastward electric field from the E region probably played a significant role in this event

Effects of Ta2O5 on the microstructure and electrical properties of ZnO linear resistance ceramics

ZnO linear resistance ceramics were synthesized from ZnO–Al _2 O _3 –MgO–TiO _2 –SiO _2 –Ta _2 O _5 by a conventional ceramics method. Effects of Ta _2 O _5 on the phase composition, microstructures, and electrical properties of ZnO linear resistive ceramics were investigated. The results show that doping with appropriate amount of Ta _2 O _5 can refine the grains of the main crystalline phase ZnO and the secondary crystalline phase ZnAl _2 O _4 in terms of microstructure, and also can reduce the grain boundary barrier and optimize the I–V characteristics in terms of electrical properties. In addition, the doping of Ta _2 O _5 can improve the stability of the resistivity , and the impedance frequency indicates that the doping of Ta _2 O _5 makes the sample suitable for high-frequency electric fields. The resistivity of the sample doped with 0.2 mol% Ta _2 O _5 is 56.2 Ω·cm, and this sample has the best grain boundary barrier height, nonlinear coefficient and temperature coefficient of resistance of 0.054 eV, 1.04 and −3.48 × 10 ^−3 °C ^−1 , respectively