BROADBAND POLARIZATION CONVERSION BASED ON SMALL-SIZE METAMATERIAL IN THE GHz BAND

We proposed a small GHz metamaterial perfect absorber, which can operate in two different functional modes depending on the orientation of unit-cell structure. Firstly, when the unit-cell structure is oriented symmetrically to the external electric-field direction, an absorption mode is achieved with a near perfect absorption peak. Secondly, by rotating the resonator structure on top layer, metamaterial is asymmetric to the external field, leading to the excitation of cross-coupling effect.

Validated high-performance thin-layer chromatographic analysis of curcumin in the methanolic fraction of Curcuma longa L. rhizomes

Background In the present study, an HPTLC (high-performance thin-layer chromatography) method was developed for the quantitative determination and validation of the curcumin in the methanolic fraction of Curcuma longa L. For achieving good separation of curcumin, the mobile phase of chloroform:methanol (97:3) was used. The densitometric analysis of curcumin was performed at 420 nm in reflection/absorption mode. Results Linearity of the method was obtained in the range of 100‒600 ng per spot. During analysis, the methanolic fraction of the C. longa showed the presence of a quantifiable amount of curcumin. The content of curcumin was found to be 1.5% (per dry weight). Conclusions The method is specific, simple, precise, and accurate. The obtained data can have used for the routine analysis of the reported biomarkers in crude drugs and extracts. The quantification and the method validation of curcumin have not yet been reported in C. longa which can be utilized for the proper standardization of the plant.

Phase Correction for Absorption Mode Two-Dimensional Mass Spectrometry

Two-dimensional mass spectrometry (2D MS) is a tandem mass spectrometry method that relies on manipulating ion motions to correlate precursor and fragment ion signals. 2D mass spectra are obtained by performing a Fourier transform in both the precursor ion mass-to-charge ratio (m/z) dimension and the fragment ion m/z dimension. The phase of the ion signals evolves linearly in the precursor m/z dimension and quadratically in the fragment m/z dimension. This study demonstrates that phase-corrected absorption mode 2D mass spectrometry improves signal-to-noise ratios by a factor of 2 and resolving power by a factor of 2 in each dimension compared to magnitude mode. Furthermore, phase correction leads to an easier differentiation between ion signals and artefacts, and therefore easier data interpretation.

Phase Correction for Absorption Mode Two-dimensional Mass Spectrometry

Two-dimensional mass spectrometry (2D MS) is a method for tandem mass spectrometry that relies on manipulating ion motions to correlate precursor and fragment ion signals. 2D mass spectra are obtained by performing a Fourier transform in both the precursor ion mass-to-charge ratio (m/z) dimension and the fragment ion m/z dimension. The phase of the ion signals evolves linearly in the precursor m/z dimension and quadratically in the fragment m/z dimension. This study demonstrates that phase-corrected absorption mode 2D mass spectrometry improves signal-to-noise ratios by a factor of 2 and resolving power by a factor of 2 in each dimension compared to magnitude mode. Furthermore, phase correction leads to an easier differentiation between ion signals and artefacts, and therefore easier data interpretation.

Plasmon–exciton interaction strongly increases the efficiency of a quantum dot–based near-infrared photodetector operating in the two-photon absorption mode under normal conditions.

Semiconductor quantum dots (QDs) are known for their high two-photon absorption (TPA) capacity. This allows them to efficiently absorb infrared photons with energies lower than the bandgap energy. Moreover, TPA...