Composite ceramics in a solid solution of (Mg1−x Mnx)2TiO4 (x=0.02–0.1) have been prepared by the mixed oxide route. Formation of the solid solution was confirmed by the X‐ray diffraction, the EDX ...analysis, and the measured lattice parameters, which varied linearly from Mg2TiO4 (a=b=c=8.4410 Å) to (Mg0.9 Mn0.1)2TiO4 (a=b=c=8.4445 Å). The XRD analysis also confirmed the co‐existence of a cubic‐structured (Mg1−xMnx)2TiO4 and an ilmenite‐structured second phase (Mg1−xMnx)TiO3. The composition expected to have a maximum Q×f (276 200 GHz at 10.5 GHz) is (Mg0.95Mn0.05)2TiO4 with ɛr∼15.69 and τf∼−52.6 ppm/°C. The existence of the second phase, however, would lead to no significant variation in the dielectric properties of the specimen because it possesses compatible properties compared with that of the main phase.
Gold nanoclusters (Au NCs) belong to a class of materials that is highly fluorescent and biocompatible. Bovine serum albumin (BSA) protected gold nanoclusters (BSA-Au NCs) have been extensively used ...in biological applications due to their easy synthesis and relatively high quantum yield. Therefore, understanding the behavior of BSA-Au NCs in different chemical and physical environments is essential to enhance their application in biological systems. In this study, we investigated the effect of plasmonic nanostructures with different localized surface plasmon resonance (LSPR) wavelengths on the behavior of BSA-Au NCs by recording time-dependent fluorescence spectra in the presence of silver nanoparticles (AgNPs) with various shapes. However, we did not observe any conclusive LSPR-wavelength-dependent fluorescent behavior. Additionally, the fluorescence intensity of BSA-Au NCs exhibited gradual decay under light excitation, even at several hundred μW/cm2 in a fluorescence spectrometer, indicating that they are not as photostable as previously assumed. We found further that the photostability of BSA-Au NCs is affected by the wavelength of the incident light (370, 420, 480, and 550 nm), which can be accurately described using bi-exponential decay functions. Our study provides an easy in situ method to evaluate the photostability of Au NCs under different-wavelength light irradiation using a commercial fluorescence spectrometer.
Vitrification and ultrarapid laser warming are crucial for the cryopreservation of animal embryos, oocytes, and other cells of medicinal, genetic, and agricultural value. In the present study, we ...focused on alignment and bonding techniques for a special cryojig that combines a jig tool and jig holder into one piece. This novel cryojig was used to obtain a high laser accuracy of 95% and a successful rewarming rate of 62%. The experimental results indicated that our refined device improved laser accuracy in the warming process after long-term cryo-storage through vitrification. We anticipate that our findings will lead to cryobanking applications that use vitrification and laser nanowarming to preserve cells and tissues from a wide range of species.
Surface-enhanced Raman Scattering (SERS) of R6G has been observed in two different silver colloids in the presence of KBr. It was found in spherical nanoparticles with an average diameter of 10 ± 2 ...nm and in their photoinduced conversion products with sodium light irradiation, silver nanoprisms, with an average edge length of 70 ± 30 nm and thickness of about 10 ± 2 nm. The SERS intensity of R6G (4.5 × 10−9 M) in the silver nanoprism colloid was 20× stronger than in the spherical nanoparticle colloid with the addition of KBr (0.05 M). Comparing the Raman signal intensity of water (55.5 M) and the SERS intensity of R6G (4.5 × 10−9 M) in the same spectrum showed that the analytical enhancement factors (AEF) in the truncated silver nanoprism colloid and spherical nanoparticle colloid are about 1.6 × 105 and 8 × 103, respectively. Monitoring the fluorescent intensity of R6G versus the concentration of R6G in two colloids in the absence of KBr displayed that the nanoprisms had better fluorescence quenching ability than the spherical nanoparticles by a factor of around 3. It implied that light irradiation not only converted the morphology of the spherical nanoparticles to nanoprisms, but also changed the surface character to have a higher affinity to the dye molecule. The surface enhancement factors (SEF) can also be calculated from AEF and the percentage of dye molecules adsorbed on the surface in the presence of KBr. The SEF of the nanoprism and spherical nanoparticle colloids are about 3.2 × 105 and 9 × 103, respectively. The UV−vis−NIR spectra and TEM images show that the spherical nanoparticles remained dispersed, while the nanoprisms were sculptured by the bromide ions after the addition of KBr.
This study successfully demonstrates the fabrication of a thin film of graphene oxide doped with silver nanoparticles (GO:AgNPs) using electrochemical exfoliation and photochemical synthesis. The ...GO:AgNPs thin film exhibits a higher work function and conductivity compared to poly3,4-ethylenedioxythiophene polystyrene sulfonate (PEDOT:PSS), making it a promising candidate for the hole-transport layer in polymer light-emitting diodes (PLEDs). Among various configurations, a PLED incorporating GO:AgNPs as the interlayer, which is prepared under blue-light illumination, exhibits optimal luminescent performance. This configuration achieves the highest luminance of 6341 cd/m2 and the highest average current efficiency of 1.87 cd/A. Notably, this novel PLED demonstrates a remarkable 168 % enhancement in average current efficiency and an impressive 637 % increase in electroluminescence intensity compared to a PLED employing a PEDOT:PSS interlayer.
Using a conventional solid‐state reaction, followed by sintering at 1080°C–1200°C Li2(Zn1−xAx)Ti3O8 (A = Mg, Co and x = 0.02–0.1) ceramic system with >96% density were prepared. The XRD patterns of ...the sintered samples revealed single‐phase formation with a cubic crystal symmetry. The molecular volume shows good linear relationship with x value. The microwave dielectric properties of Li2(Zn1−xAx)Ti3O8 ceramics exhibited a significant dependence on the x value and to some extent on the morphology of the specimens. The Li2(Zn0.94Mg0.06)Ti3O8 ceramics possess εr = 26.1, Q × f = 150 000 GHz, and τf = −13.9 ppm/°C, and Li2(Zn0.92Co0.08)Ti3O8 ceramics show εr = 24.7, Q × f = 140 000 GHz, and τf = −13.4 ppm/°C, respectively. It indicates a substantial increase in the Q × f in comparison with that of pure Li2ZnTi3O8. The microwave dielectric properties of these partially substituted ceramics are reported for the first time.
The feasibility of novel LiCo
1-x
A
x
VO
4
(A = Mg, Zn; x = 0-0.09) microwave dielectrics for ULTCC (ultra-low temperature co-fired ceramics) applications was investigated. Continuous solid solutions ...were formed as expected in the whole composition range and can be indexed in the cubic system with the Fd3m space group. The Raman spectrum of the specimen was also analyzed. All samples can be sintered into dense ceramics (relative density> 97%) at the temperature 650°C. The variation of structure parameters resulted from minutely substituting Co with Mg or Zn has significant effect on the microwave dielectric properties of the specimen. The relative density and dielectric polarizability have significant impact on the ɛ
r
of the specimens. Q × f value is dominated by the density and packing fraction of the ceramics. The τ
f
, however, was mainly controlled by the bond-valence of the samples under a minute substitution. Specimen with 0.01 mol% Zn-substitution at 650°C revealed the highest Q × f of 53,000 GHz along with an ε
r
of 13.2 and a τ
f
of - 57.5 ppm/°C. It also exhibited a good Al-cofiring chemical compatibility.
Novel Li1−2xMxVO3 (M = Mg, Zn) (x = 0–0.09) microwave dielectrics suitable for ULTCC (ultra-low temperature co-fired ceramics) applications were synthesized. The X-ray diffraction patterns revealed ...that all samples were monoclinic structured with a space group of C2/c. Microstructures, lattice parameters, and Raman spectra of the ceramics were also studied. Q×f (Q: quality factor) was mainly controlled by intrinsic and extrinsic loss, while the variation of τf (temperature coefficient of resonant frequency) was related to ceramic bond valence. Poor microwave dielectric properties of pure LiVO3 can be tremendously enhanced by substituting a minute amount of Mg or Zn in place of Li. Excellent properties could be obtained for specimens sintered at 520 °C with an εr of 9.78, a Q×f of 45,600 GHz and an τf of –45 ppm/°C for Li0.98Mg0.01VO3, in addition to an εr (dielectric constant) of 9.25, a Q×f of 33,100 GHz and an τf of –53.6 ppm/°C for Li0.98Zn0.01VO3. Furthermore, the Li0.98Mg0.01VO3 specimen was found to be chemically comparable with the Al electrode. With 2 mol% of TiO2 added, the specimen at 520 °C achieved excellent characteristics which include an εr of 9.2, a Q×f of 30,000 GHz, and an τf of –2.8 ppm/°C, making it a very promising ULTCC dielectric for high-frequency 5 G applications.
SrCo
1-x
Mg
x
V
2
O
7
(x = 0-0.09) dielectrics were prepared via the solid state route and the effect of Mg substitution on the microwave dielectric properties of the ceramics was systematically ...investigated. In addition to the relative density and microstructure, the dielectric polarizability, packing fraction, lattice energy and bond valence also play a crucial role in controlling the dielectric properties of the ceramics at microwave frequencies. A high lattice energy representing a high structural stability leads to a low dielectric loss in the specimen. Fluctuated variation of the τ
f
was highly related to the bond valence of the samples. Specimens with x = 0.07 at 660°C revealed the highest Q × f of 23,000 GHz along with an ε
r
of 13.2 and a τ
f
of - 95 ppm/°C and it is chemically compatible with the Al electrode, suggesting that the dielectric is highly promising for ULTCC applications.
PDF
