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In this article, a simple and effective carbon quantum dots (CQDs) was designed by one-step hydrothermal method from common vegetable carrots. This carbon quantum dots solution was used as a probe with excellent fluorescence properties for the analysis of local anesthetic lidocaine, and it obtained better recoveries and detection effects in real sample spiked recovery experiments, with a limit of detection of 20.52 nM, a linear detection range of 0.25-50 mM, and the recovery of 82.7-101.3% in actual samples. Highly fluorescence of carrot-CQDs were quenched by lidocaine with inner filter effect. The morphology of the carrot-CQDs and the surface functional groups were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and fluorescence spectrophotometry. The CQDs exhibited good acid and alkali resistance, salt resistance, and photobleaching resistance under different conditions. Therefore, it provided a new insight on the detection of lidocaine by the carrot -CQDs as nanosensors. [ABSTRACT FROM AUTHOR]

OBJECTIVE: This work aimed to study the mechanism of lncRNATCF7 upregulating DNMT1 mediated by HPV-18 E6 and regulating the biological behavior of cervical cancer cells by inhibiting miR-155. PATIENTS AND METHODS: HPV-16 E6 enhanced DNMT1 expression in cervical cancer cells, which was detected by Western blotting. The expression of miR-155 in cervical cancer was detected by qPCR, the interaction between TCF-7 and miR-155 by Dual-Luciferase reporter gene. The changes in invasion ability of cervical cancer cells and the effect of miR-155 on the invasion ability of cervical cancer cells after inhibiting TCF-7 were detected by the transwell invasion assay, while changes in migration ability of cervical cancer cells and the effect of miR-155 on migration ability of cervical cancer cells after inhibiting TCF-7 were observed by the scratch assay. The effect of inhibiting TCF-7 on the tumor size and volume of cervical cancer was detected by the subcutaneous tumor formation in nude mice. RESULTS: E6 expression was significantly inhibited by E6 siRNA. The knockdown of endogenous HPV-16 E6 markedly inhibited the expression of DNMT1; TCF-7 specifically bound to the 3' UTR of miR-155; inhibition of TCF-7 can inhibit invasion and migration of cervical cancer cells; enhanced miR-155 after the inhibition of TCF-7 can promote the invasion and migration of cervical cancer cells; compared with NC group, the tumor volume and weight of TCF-7-siRNA group tumor-bearing was significantly reduced. CONCLUSIONS: TCF-7 plays an important role in the development of cervical cancer. TCF-7 can target miR-155 to regulate the invasion and migration of cervical cancer cells. [ABSTRACT FROM AUTHOR]

Hall measurements are performed to survey electrical properties of p-Pb1-xMnxSe (x≈0.04) films grown by molecular beam epitaxy technique. It is indicated that these films are approaching the metal-insulator transition from the metallic side. Weak localization effect was observed up to about 50 K. The deduced phase-breaking time τ[lowercase_phi_synonym] on temperature is interpreted according to the concept of the electron–electron scattering in highly disordered bulk conductors. [ABSTRACT FROM AUTHOR]

Characterization of a IV-VI semiconductor structure consisting of a PbSe/PbSrSe multiple quantum well (MQW) active region between distributed Bragg reflectors grown by molecular beam epitaxy on a Si(111) substrate is described. Pulsed photoluminescence (PL) spectra exhibited interband electronic transition energies ranging linearly with temperature from 231.4 meV at 150 K to 299.4 meV at 300 K, while continuous wave (cw) PL spectra exhibited only the vertical optical cavity mode with emission varying between 299.2 meV at 150 K to 301.1 meV at 300 K. A maximum PL emission power of approximately 1.8 mW was obtained for cw diode laser pumping when the heat sink temperature was 200 K. Data are consistent with a localized epilayer heating effect of about 100 deg where the interband electronic transition energy is coincident with the vertical optical cavity mode. In spite of significant sample heating and associated thermal expansion mismatch stress, cw PL emission intensity was stable with no noticeable degradation in intensity after repeated measurements. These results show that IV-VI epitaxial layers on silicon are viable materials for fabricating reliable light emitters for on-chip optical interconnects. [ABSTRACT FROM AUTHOR]

Room-temperature photoluminescence (PL) measurements of IV-VI semiconductor multiple quantum well (MQW) structures using diode laser optical pumping at two different excitation wavelengths, 2.5 and 0.91 μm, are described. Active region temperatures during continuous-wave optical pumping were determined from blueshifts in PL emission energies. Temperatures were between 22.7 and 29.5 °C lower for 2.5-μm pumping as compared to 0.91-μm pumping at the same power level of 100 mW. Heating effects are also shown to be smaller for MQW samples with more narrow PbSe wells. [ABSTRACT FROM AUTHOR]

Refractive indices for cubic-phase MgxZn1-xO (0.55<=x<=1) thin-film alloys were determined from transmission measurements and Manifacier envelope method. The refractive index of cubic MgxZn1-xO decreases with the Mg fraction increase, such as at the wavelength of 400 nm the refractive index decreases from 1.89 to 1.73 as x increases from 0.57 to 1.0. The refractive index dispersion relation of cubic MgxZn1-xO in the visible-light region (400–800 nm) follows the first-order Sellmeier equation and decreases with the increase of Mg fraction. [ABSTRACT FROM AUTHOR]

Absorption, reflection and Raman scattering measurements have been carried out for the optical properties of a SrSe thin film grown by molecular beam epitaxy on a BaF[sub 2] (111) substrate. The film quality and lattice constant have been assessed by x-ray diffraction, where the good quality of the SrSe thin film is evident in a full width at half maximum value of 310 arcsec. Temperature-dependent indirect band gaps are obtained with the aid of temperature-dependent absorption measurements from 16 to 300 K on the SrSe thin film. By fitting the far-infrared reflection spectra, transverse optical phonon reflection bands in the binary SrSe thin film have been assigned, which are further verified by temperature-dependent Raman scattering measurements. [ABSTRACT FROM AUTHOR]

Temperature-dependent infrared transmission measurements on molecular-beam-epitaxy-grown PbSe/Pb[sub 0.934]Sr[sub 0.066]Se multiple-quantum-well structures (MQWs) have been carried out for the study of line shape broadening mechanisms. The longitudinal-optical phonon scattering strength is found to be much smaller in PbSe/Pb[sub 0.934]Sr[sub 0.066]Se MQWs (∼11-12 meV) than that in the corresponding IV-VI films (∼51 meV), which is in good agreement with the theoretical prediction. The low-temperature transmission line shapes of PbSe/Pb[sub 0.934]Sr[sub 0.066]Se MQWs are analyzed on the basis of the modeling of three broadening mechanisms. For the transmission spectra, the line shape broadening is mainly due to the well width fluctuation for quantum wells thinner than 15 nm and due to the interface roughness for quantum wells thicker than 15 nm. However, the line shape broadening due to the sheet carrier density in PbSe wells has been found to play a dominant role in the photoluminescence linewidth. [ABSTRACT FROM AUTHOR]

Pb[sub 1-x]Sr[sub x]Se thin films grown by molecular beam epitaxy have been investigated by x-ray diffraction and temperature-dependent photoluminescence measurements with the Sr composition as high as 0.276. Temperature and composition dependent excitonic line broadening effects in PbSrSe thin films have been studied on the basis of the proposed theoretical models and the experimentally obtained lattice constant, excitonic energy gap and effective mass as a function of the alloy composition. The exciton-longitudinal optical phonon coupling model has been employed successfully for PbSrSe with a coupling strength of 51.0 meV, which can be well explained by the proposed theoretical approach. The lattice deformation may have played a key role in the composition dependent broadening in PbSrSe at low temperature, rather than the normally observed alloy disorder effect in III–V and II–VI semiconductor materials. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Key properties of PbSrSe thin films grown by molecular beam epitaxy have been studied for mid-infrared optoelectronic device applications. Detailed knowledge of the material parameters for the device design is required. The material parameters considered are: temperature-dependent band gaps, composition (or band gap)-dependent effective masses, and energy-dependent refractive indices. The study has been carried out by a combination of temperature-dependent photoluminescence and absorption measurements with the theoretical models on PbSrSe thin films of Sr compositions of as high as 0.276. The derived empirical equations for band gaps, effective masses, and refractive indices have been employed successfully in PbSe/Pb[sub 0.934]Sr[sub 0.066]Se multiple quantum well mid-infrared laser systems, for studying the band offsets and subband behavior. We have shown that the derived material parameters clearly promise of being applied to other PbSrSe thin films and PbSe/PbSrSe heterostructure systems for their optoelectronic applications. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Above room temperature continuous wave midinfrared photoluminescence has been observed from PbSe/Pb[sub 1-x]Sr[sub x]Se multiple quantum well structures grown by molecular beam epitaxy on (111) silicon. Emission energy from a sample with 10-nm-thick quantum wells varied from 336.1 to 343.7 meV as sample temperature was increased from 15 to 35 °C. At a heat sink temperature of 25 °C the emission energy varied from 336.8 to 339.9 meV as the current in the near-infrared diode pump laser was increased from 300 to 800 mA indicating an additional 8.2 °C of epilayer heating due to increased photon flux from the pump laser. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]