Label-free, real-time, and in-situ measurement on cell apoptosis is highly desirable in cell biology. We propose here a design of terahertz (THz) metamaterial-based biosensor for meeting this requirement. This metamaterial consists of a planar array of five concentric subwavelength gold ring resonators on a 10 μm-thick polyimide substrate, which can sense the change of dielectric environment above the metamaterial. We employ this sensor to an oral cancer cell (SCC4) with and without cisplatin, a chemotherapy drug for cancer treatment, and find a linear relation between cell apoptosis measured by Flow Cytometry and the relative change of resonant frequencies of the metamaterial measured by THz time-domain spectroscopy. This implies that we can determine the cell apoptosis in a label-free manner. We believe that this metamaterial-based biosensor can be developed into a cheap, label-free, real-time, and in-situ detection tool, which is of significant impact on the study of cell biology.
In order to obtain an atomic grating which can diffract light into the high-order directions more efficiently, a gain-phase grating (GPG) based on the spatial modulation of active Raman gain is theoretically presented. This grating is induced by a pump field and a standing wave in ultracold atoms, and it not only diffracts a weak probe field propagating along a direction normal to the standing wave into the high-order directions, but also amplifies the amplitude of the zero-order diffraction. In contrast with electromagnetically induced grating or electromagnetically induced phase grating, the GPG has larger diffraction efficiencies in the highorder directions. Hence it is more suitable to be utilized as an all-optical router in optical networking and communication.
Microwave
dielectric ceramics exhibiting a low dielectric constant
(ε
r
), high quality
factor (Q × f), and thermal stability, specifically
in an ultrawide temperature range (from −40 to +120 °C),
have attracted much attention. In addition, the development of 5G
communication has caused an urgent demand for electronic devices,
such as dielectric resonant antennas. Hence, the feasibility of optimizing
the dielectric properties of the SmNbO4 (SN) ceramics by
substituting Bi3+ ions at the A site was studied. The permittivity
principally hinges on the contribution of Sm/Bi–O to phonon
absorption in the microwave range, while the reduced sintering temperature
results in a smaller grain size and slightly lower Q ×
f value. The expanded and distorted crystal cell indicates
that Bi3+ doping effectively regulates the temperature
coefficient of resonant frequency (TCF) by adjusting the strains (causing
the distorted monoclinic structure) of monoclinic fergusonite besides
correlating with the permittivity. Moreover, a larger A-site radius
facilitates the acquisition of near-zero TCF values. Notably, the
(Sm0.875Bi0.125)NbO4 (SB0.125N) ceramic with ε
r
≈ 21.9, Q × f ≈ 38 300
GHz (at ∼8.0 GHz), and two different near-zero TCF values of
−9.0 (from −40 to +60 °C) and −6.6 ppm/°C
(from +60 to +120 °C), respectively, were obtained in the microwave
band. A simultaneous increase in the phase transition temperature
(T
c) and coefficients of thermal expansion
(CTEs) by A-site substitution provides the possibility for promising
thermal barrier coating (TBC) materials. Then, a cylindrical dielectric
resonator antenna (CDRA) with a resonance at 4.86 GHz and bandwidth
of 870 MHz was fabricated by the SB0.125N specimen. The
exceptional performance shows that the SB0.125N material
is a possible candidate for the sub-6 GHz antenna owing to the advantages
of low loss and stable temperature.
Colloidal cadmium chalcogenide nanoplates are two-dimensional semiconductors that have shown significant application potential for light-emitting technologies. The self-trapped state (STS), a special localized state originating from strong electron-phonon coupling (EPC), is likewise promising for use in one-step white light luminance owing to its broadband emission line width. However, achieving STS in cadmium chalcogenide nanocrystals is extremely challenging owing to their intrinsically weak EPC nature. By building hybrid superlattice (SL) structures via self-assembly of colloidal CdSe nanoplates (NPLs), we demonstrate in this paper zone-folded longitude acoustic phonons (ZFLAPs), which differ from monodispersed NPLs. A broadband STS emission in the spectra range of 450-600 nm is thereby observed. Through femtosecond transient absorption and impulsive vibrational spectroscopy, we reveal that STS is generated in a time scale of approximately 500 fs. It is driven by strong coupling of excitons and ZFLAPs with a Huang-Rhys parameter of approximately 22.7. Our findings provide a novel foundation for generating and manipulating STS emissions by artificially designing and building hybrid periodic structures that are superior to single-material optimization.Ultrathin colloidal CdX (X = S, Se, Te) nanoplates (NPLs) with a uniform atomic thickness [1][2][3][4] form a new class of two-dimensional material. They have attracted considerable attention in past decades for their excellent optical properties, such as a narrow line width 4,5 due to strong quantum thickness confinement, a high luminescent quantum yield 6 due to minimization of surface traps, and large mode gain coefficients 7-9 due to suppressed Auger recombination. These remarkable optical properties, together with their cost-effective preparation and notable stability, have made colloidal CdX NPLs promising as optoelectronic materials that can be used in light-emitting
The vital role of the charged moieties of monovalent aromatic anions in regulating the aggregation of a cationic conjugated polyelectrolyte was exploited in terms of the hard-soft acid-base principle and its application to colorimetric sensing of taurine was examined.
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