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Novel scheelite‐type [Ca0.55(Nd1‐xBix)0.3]MoO4 (0.2 ≤ x ≤ 0.95) ceramics were prepared using the solid‐state reaction method. According to the X‐ray diffraction data, a solid solution was formed in 0.2 ≤ x ≤ 0.95 and all the samples belong to pure scheelite phase with the tetragonal structure. As revealed by Raman spectroscopy, the number of vibrational modes decreased with the increase in x value, which further indicated that Bi3+ ions occupied A‐site of scheelite structure. As the x value increased, the sintering temperature decreased from 740°C to 660°C; the permittivity increased from 12.6 to 20.3; the Qf value first decreased slightly and gradually remained stable. Based on the infrared reflectivity spectrum analysis, the calculated permittivity derived from the fitted data shared the same trend with the measured value. The [Ca0.55(Nd0.05Bi0.95)0.3]MoO4 ceramic sintered at 660 °C attained a near‐zero value temperature coefficient ~τf (−7.1 ppm/°C) and showed excellent microwave dielectric properties with a ɛr ~ 20.3 and a Qf ~ 33 860 GHz, making this system a promising candidate in the ultralow temperature cofired ceramic (ULTCC) technology. [ABSTRACT FROM AUTHOR]

Novel high quality factor microwave dielectric ceramics (1− x)ZrTiO4− x(Mg1/3Nb2/3)TiO4 (0.325≤ x≤0.4) and (ZrTi)1− y(Mg1/3Nb2/3) yO4 (0.2≤ y≤0.5) with the addition of 0.5 wt% Mn CO3 in the (Mg1/3Nb2/3)O2-ZrO2-TiO2 ternary system were prepared, using solid-state reaction method. The relationship between the structure and microwave dielectric properties of the ceramics was studied. The XRD patterns of the sintered samples reveal the main phase belonged to α-PbO2-type structure. Raman spectroscopy and infrared reflectivity ( IR) spectra were employed to evaluate phonon modes of ceramics. The 0.65ZrTiO4−0.35(Mg1/3Nb2/3)TiO4−0.5 wt% Mn CO3 ceramic can be well densified at 1240°C for 2 hours and exhibits good microwave dielectric properties with a relative permittivity (εr) of 42.5, a quality factor ( Q× f) value of 43 520 GHz (at 5.9 Ghz) and temperature coefficient of resonant frequency (τf) value of −5ppm/°C. Furthermore, the (ZrTi)0.7(Mg1/3Nb2/3)0.3O4−0.5 wt% Mn CO3 ceramic sintered at 1260°C for 2 hours possesses a εr of 31.8, a Q×f value of 35 640 GHz (at 6.3 GHz) and a near zero τf value of −5.9 ppm/°C. The results demonstrated that the (Mg1/3Nb2/3)O2-ZrO2-TiO2 ternary system with excellent properties was a promising material for microwave electronic device applications. [ABSTRACT FROM AUTHOR]

In this work, a series of scheelite solid solution [(Li0.5Ln0.5)1− xCa x]MoO4 (Ln = Sm and Nd; x = 0.20, 0.40, 0.60, 0.70, 0.80, 0.85, 0.90) ceramics were prepared by conventional solid-state reaction method. The sintering temperature was lowered to 925°C by (Li0.5Ln0.5)2+ substituting for Ca2+ in the solid solution without any secondary phase. Compared with that of scheelite CaMoO4 (−57 ppm/°C), the temperature coefficient of resonant frequency (TCF or τf) of the scheelite solid solution was modified to near zero (about +4.3 ppm/°C) at x = 0.8 with a dielectric constant 11.0 and the quality factor ( Q × f value) of 18 695 GHz. The Raman spectra, showed the degree of disordering increased with x value, which resulted in decrease in the permittivities and increase in the Q × f values. The infrared spectra were analyzed using the classical harmonic oscillator model and were extrapolated to the microwave range. The chemical compatibility with silver electrode indicated that the reported series of ceramics were good candidates for the low-temperature cofired ceramic applications. [ABSTRACT FROM AUTHOR]

In the present work, ( Bi1− x Fe x) VO4 ( x ≤ 0.40) ceramics were prepared using the solid-state reaction method. All the ceramics could be well densified at sintering temperatures below 800°C. X-ray diffraction ( XRD) results showed that monoclinic solid solution was formed within x ≤ 0.08. When x ≥ 0.10, both monoclinic scheelite and FeVO4 phases were detected. The ( Bi0.92 Fe0.08) VO4 sample sintered at 720°C for 2 h had a permittivity of 57.5 and a Qf value of 15 000 GHz. The IR reflectivity was fitted to study the intrinsic dielectric properties, showing that the majority of the dielectric contribution for this system at microwave region was attributed to the absorptions of structural phonon oscillation in infrared region. [ABSTRACT FROM AUTHOR]

The modifications of epithelial differentiation and proliferation observed in nasal polyps (NP) could be related to local secretion of growth factors, among which platelet-derived growth factor (PDGF) could play a key role. We therefore prospectively studied, by immunohistochemistry, proliferating cell nuclear antigen (PCNA, an S-phase cell marker), PDGF, and CD-68 (activated macrophages marker) expression in NP and inferior turbinate mucosa (NM) in 11 patients. Our data show that PCNA and PDGF expression are increased in NP epithelium, while CD-68 expression is increased in NP epithelium and lamina propria when compared to NM. Increased local PDGF secretion by numerous activated macrophages could therefore be involved in epithelial cell proliferation up-regulation in NP. PDGF could also be involved in the pathogenesis of NP via its connective tissue remodeling actions. Laryngoscope, 106:578-583, 1996 [ABSTRACT FROM AUTHOR]