The optical properties of $\mathrm{K}{\mathrm{Ca}}_{2}{\mathrm{Fe}}_{4}{\mathrm{As}}_{4}{\mathrm{F}}_{2}$ (K12442, ${T}_{c}=33.5$ K) and $\mathrm{K}{\mathrm{Ca}}_{2}{({\mathrm{Fe}}_{0.95}{\mathrm{Ni}}_{0.05})}_{4}{\mathrm{As}}_{4}{\mathrm{F}}_{2}$ (Ni-K12442, ${T}_{c}=29$ K) have been examined at a large number of temperatures. For both samples, a nodeless superconducting gap is clearly observed in the optical conductivity at 5 K. The superconducting gap $\mathrm{\ensuremath{\Delta}}\ensuremath{\simeq}8.7$ meV ($2\mathrm{\ensuremath{\Delta}}/{k}_{\text{B}}{T}_{c}\ensuremath{\simeq}6.03$) in K12442, pointing towards strong-coupling Cooper pairs, but in sharp contrast, $\mathrm{\ensuremath{\Delta}}\ensuremath{\simeq}4.6$ meV ($2\mathrm{\ensuremath{\Delta}}/{k}_{\text{B}}{T}_{c}\ensuremath{\simeq}3.68$) in Ni-K12442, which agrees with the BCS weak-coupling pairing state. More intriguingly, below ${T}^{*}\ensuremath{\simeq}75$ K, the optical conductivity of K12442 reveals a pseudogap that smoothly evolves into the superconducting gap below ${T}_{c}$, while no such behavior is detected in the electron-doped Ni-K12442. The comparison between the two samples suggests that the pseudogap and strong-coupling Cooper pairs in K12442 may be intimately related to the shallow and incipient bands. We provide arguments supporting a preformed pairing mechanism of the pseudogap, but at the moment a magnetic scenario cannot yet be excluded.
The effect of oscillating magnetic field on the anisotropic susceptibility of a spin S = 1/2 anisotropic three-dimensional Heisenberg ferromagnet, is studied by the double-time Green's function method within Tyablikov approximation. The results show that the magnetic resonant frequencies directly and sensitively depend on the exchange anisotropic constant (α), and the directions of applied magnetic field. In the case of transverse oscillating field, the transverse susceptibilities exhibit strong resonant effect, and the positions of resonant frequency are sensitive and change monotonically to α. However, in the case of longitudinal oscillating field, the longitudinal susceptibilities are rather flat and display no resonant effect. Therefore, transverse ferromagnetic resonance is a precise technique to measure the magnitude of α, and this conclusion is very useful in the alloy multilayer application.
Objective
To investigate the application value of pH sensitive manganese-loaded caramelized carbonaceous nanospheres (Mn-CNS) in the synchronous MRI and photothermal therapy for breast cancer.
Methods
Anhydrous glucose was used as carbon source to prepare caramelized carbonaceous nanospheres (CNS). Mn2+ was absorbed and bonded to its surface to obtain the Mn-CNS. The MR signal values of aqueous solutions of Mn-CNS under different pH (pH= 7.4, 6.0, 5.0) with different Mn2+ concentrations (0, 0.14, 0.28, 0.57, 1.14 and 2.28 mmol/L) were measured to obtain the relaxation rate. The cell counting kit-8 (CCK-8) assay was used to determine the effect of Mn-CNS on the viability of 4T1 cells. Pathological examination was used to evaluate the systemic toxicity. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze Mn uptake by different cell lines (human breast cancer cells MCF-7, human normal mammary epithelial cells MCF-10A and human macrophages cells). The 4T1 tumor-bearing BALB/c mice were divided randomly into four groups (6 mice per group): (1) normal saline (intratumoral injection) plus near infrared laser (NIR);(2) normal saline (intravenous injection) plus NIR;(3) Mn-CNS (intratumoral injection) plus NIR;(4) Mn-CNS (intravenous injection) plus NIR. After intratumoral injection for 30 min and intravenous injection for 12 h, the tumors were continuously irradiated with 808 nm laser for 10 min, the temperature changes and relative tumor volume were recorded. The MRI was obtained at different time point (pre-injection and post-injection at 15 min, 30 min, 1 h, 4 h, 8 h, 12 h, 24 h, 48 h, 4 d, respectively) with the dose of Mn-CNS (4 mg Mn/kg) by intravenous injection. The changes of Mn2+ content before and after Mn-CNS incubation and the tumor volume differences among each group were compared by t test.
Results
The values of r1 were 0.18 L·mmol-1·s-1 (pH 5.0), 3.48 L·mmol-1·s-1 (pH 6.0) and 5.42 L·mmol-1·s-1 (pH 7.4), respectively. The cells viability of 4T1 were all above 90% when the cells were incubated with Mn-CNS at different concentrations (25, 50, 100 and 200 μg/ml). MCF-7 and human macrophages cells were ingested Mn2+. The Mn2+ amount before and after uptake were significant difference (P 0.05). After 10 minutes of the laser exposure (2 w/cm2), the change of temperature with tumor among different groups were shown as follow: Mn-CNS (intratumoral injection)>Mn-CNS (intravenous injection)>normal saline (intravenous injection)>normal saline (intratumoral injection). After photothermal therapy, the relative tumor volumes of Mn-CNS (intratumoral injection) and normal saline (intratumoral injection) were statistically different (t=-2.724, P<0.05). Meanwhile, the relative tumor volumes also showsd significant difference among Mn-CNS (intravenous injection) and normal saline (inject intravenous injection) groups (t=-5.193, P<0.05). After intravenous injection of Mn-CNS in 4T1 tumor-bearing mice, the signal intensity of T1 gradually increased and reached the peak of enhancement at 4 h after which the signal intensity remained stable and decreased slightly at 12 h, then gradually decreased to normal. The T1 signal intensity of kidney was consistent with that of the tumor and higher. Meanwhile, the degree of liver tissue enhancement was the lowest.
Conclusions
Mn-CNS is highly biocompatible and self-degradable, it can targeted MRI and achieve precise photothermal therapy simultaneously, which is of great value in the integrated diagnosis and treatment of breast cancer.
Key words:
Breast neoplasms; Photothermal therapy; Magnetic resonance imaging; Biocompatibility; Biodegradability
In a forced light scattering experiment, after the diffraction efficiency arrives to a stable state, both direct current (DC) voltage and two writing beams are turned off, and then by reapplication of the DC voltage we observed a peak. We provide an explanation based on periodically changed anchoring energy and also discuss the evolution of diffraction efficiency under different grating constants, laser polarization, and the direction of the optical axis of a liquid crystal cell. Experiment results show that photo-introduced charge density is nearly in proportion to the intensity of writing beams.
Sensitive and accurate determination of a small quantity of hydrogen peroxide (H2O2) is of great importance in environmental analysis. In this article, a novel strategy for fabrication of H2O2 sensor was developed by electrodepositing silver nanoparticles (Ag NPs) on a DNA–multiwalled carbon nanotubes (DNA-MWCNTs) composites–modified glassy carbon electrode. Experimental results showed that the constructed electrode had an excellent catalytic ability for the reduction of H2O2, suggesting that it could be used as a sensor to detect H2O2. The good catalytic activity was ascribed to the DNA-MWCNTs composites that resulted in the formation of small Ag NPs and homogenous distribution of these Ag NPs. The sensor showed a high sensitivity, wide linear range, and good stability, and thus it could be used as an ideal tool in environmental engineering.
In attempting to extend the utility of liquid crystals (LCs) in optics, the authors show that the orientation of the electric-field-induced convection patterns of a cholesteric LC can be modified via ultraviolet (UV) irradiation. This tunability is due to a photosensitive chiral dopant, which can change its molecular shape upon illumination; this makes the pitch of the cholesteric helical structure dependent on the intensity of the UV light, while the pattern's orientation is governed by the thickness-to-pitch ratio. This phenomenon allows the design of innovative photonic devices, such as light deflectors switchable by UV pulses.
We examined the flexodomains (FDs) in chiral bent-core nematics (BCNs), and demonstrated the morphology changed from parallel stripes in pure BCN to oblique ones in chiral BCNs. While the magnitude of obliqueness angle strongly depended on the concentration of chiral dopant, its sign was determined by the polarity of the driving voltage, thus FDs appeared alternately as symmetrical oblique stripes in the positive and negative half a.c. voltage cycles, respectively. Also the HTP value of chiral dopant in BCNs can be determined based on this phenomenon. The polarity-dependent behavior of FDs can be potentially exploited in photonic devices with a bistable function.
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