Cloaking and imaging at the same time

In this letter, we propose a conceptual device to perform subwavelength imaging with positive refraction. The key to this proposal is that a drain is no longer a must for some cases. What's more, this device is an isotropic omnidirectional cloak with a perfect electric conductor hiding region and shows versatile illusion optical effects. Numerical simulations are performed to verify the functionalities.Comment: 15 pages, 4 figure

Preparation and Characterization of a Complex of Paeonol and Hydroxypropyl-β-cyclodextrin

Purpose: To improve the solubility of paeonol in water by complexing with hydroxypropyl-β-cyclodextrin (HP-β-CD) and also to characterize the physicochemical properties of the complex.Methods: The complex of paeonol and HP-β-CD was prepared by freeze-drying method. Its physicochemical properties were studied by phase-solubility method, ultraviolet-visible spectrometry (UV), infrared spectrometry (IR), scanning electron microscopy (SEM), x-ray diffractometry (XRD) and  thermogravimetric/differential scanning calorimetry (TG/DSC).Results: The phase-solubility results showed that paeonol formed a 1:1 stoichiometric complex with HP-β-CD while UV and IR spectra suggested that HP-β-CD and paeonol in the complex interacted by a non-covalent bond. SEM and XRD indicate that the heat stability of paeonol was significantly improved by complexing with HP-β-CD.Conclusion: Paeonol can be efficiently complexed with HP-β-CD to form a complex by freeze-drying method. The aqueous solubility and heat stability of paeonol is significantly improved by complexation HP-β-CD.Keywords: Paeonol, Hydroxypropyl-β-cyclodextrin, Complexation, Aqueous solubility, Heat stabilit

Resistance comparison of domesticated silkworm (Bombyx mori L.) and wild silkworm (

In this study, the resistance difference to phoxim between Bombyx mori L. and Bombyx mandarina M was investigated. For the both silkworm species, the whole body of each larval were collected, and on the third day of the 5th instar, the brain, midgut, fat bodies, and silk gland were collected for enzymatic activity assay of acetylcholinesterase (AChE). Our results showed that in the early larval stages, the resistance difference to phoxim was not significant between the two species. However, in the 4th and 5thinstar, the resistance differences showed significant increase. When compared to B. mori L, the LC50 of B. mandarina was 4.43 and 4.02-fold higher in the 4th and 5th instar, respectively. From the 1st to 5thinstar, the enzymatic activities of AChE of B. mandarina were 1.60, 1.65, 1.81, 1.93 and 2.28-fold higher than that of B. mori, respectively. For the brain, midgut, fat body, and silk gland on the third day of the5th instar, the enzymatic activity ratios of B. mandarina to B. mori were 1.90, 2.23, 2.76, and 2.78, respectively. The AChE-I50 values of B. mori and B. mandarina detected by eserine method were 5.02 × 10-7 and 5.23 × 10-7 mol/L, respectively. Thus, our results indicate that the higher enzymatic activities of AChE and the insensitivity to specific inhibitor of the enzyme might be the underlying mechanisms for higher phoxim resistance in B. mandarina

Topological Electronic Structure and Its Temperature Evolution in Antiferromagnetic Topological Insulator MnBi2Te4

Topological quantum materials coupled with magnetism can provide a platform for realizing rich exotic physical phenomena, including quantum anomalous Hall effect, axion electrodynamics and Majorana fermions. However, these unusual effects typically require extreme experimental conditions such as ultralow temperature or sophisticate material growth and fabrication. Recently, new intrinsic magnetic topological insulators were proposed in MnBi2Te4-family compounds - on which rich topological effects could be realized under much relaxed experimental conditions. However, despite the exciting progresses, the detailed electronic structures observed in this family of compounds remain controversial up to date. Here, combining the use of synchrotron and laser light sources, we carried out comprehensive and high resolution angle-resolved photoemission spectroscopy studies on MnBi2Te4, and clearly identified its topological electronic structures including the characteristic gapless topological surface states. In addition, the temperature evolution of the energy bands clearly reveals their interplay with the magnetic phase transition by showing interesting differences for the bulk and surface states, respectively. The identification of the detailed electronic structures of MnBi2Te4 will not only help understand its exotic properties, but also pave the way for the design and realization of novel phenomena and applications.Comment: 18 pages, 4 figur

Effect of a Zn impurity on T_c and its implication to pairing symmetry in LaFeAsO1−x_{1-x}Fx_x

The effect of non-magnetic Zn impurity on superconductivity in LaFe$_{1-y}$Zn$_y$AsO$_{1-x}$F$_x$ system is studied systematically. In the presence of Zn impurity, the superconducting transition temperature increases in the under-doped regime, remains unchanged in the optimally doped regime, and is severely suppressed in the over-doped regime. Our results suggest a switch of the symmetry of the superconducting order parameters from a $s$-wave to $s_{\pm}$ or $d$-wave states as the charge carrier doping increases in FeAs-based superconductors.Comment: 4 pages, 4 figures. Format changed and a few revisons mad

Phenothiazine-based copolymer with redox functional backbones for organic battery cathode materials

Organic battery materials are receiving increasing attention owing to their elemental abundance, environmental sustainability, and structural diversity. Challenges including the solubility in electrolytes, moderate redox potentials and inactive molecular fragments prevent organic materials from being ideal cathodes for practical implementation. Although polymerization, salification and alike are effective in lowering the solubility in electrolytes, they unavoidably bring additional inactive fragments into the molecular structures, resulting in the sacrifice of theoretical galvanometric capacity compared with the pristine molecule. In this study, we use two redox-active fragments to construct an insoluble copolymer as a cathode material for organic batteries. The copolymer avoids the use of unnecessary molecular weight while maintaining high specific capacity and cycling stability. We find that a twisted geometry between the two redox-active fragments leads to a cross-conjugation effect that further consolidates the low stability of individual fragment and enhances the flexibility of copolymer chains by forming mesopores that accelerate ion diffusion. The copolymer shows a high capacity of 142.5 mAh g^{-1} with energy/power density of 577 Wh kg^{-1}/1685 W kg^{-1} and a decent capacity retention of 87% after 500 cycles. Our strategy demonstrates the feasibility of designing organic battery materials that are qualified for taking solubility, capacity, and stability into consideration

Obvious enhancement of the total reaction cross sections for 27,28^{27,28}P with 28^{28}Si target and the possible relavent mechanisms

The reaction cross sections of $^{27,28}$P and the corresponding isotones on Si target were measured at intermediate energies. The measured reaction cross sections of the N=12 and 13 isotones show an abrupt increase at $$. The experimental results for the isotones with $Z\leq 14$ as well as $$P can be well described by the modified Glauber theory of the optical limit approach. The enhancement of the reaction cross section for $^{28}$P could be explained in the modified Glauber theory with an enlarged core. Theoretical analysis with the modified Glauber theory of the optical limit and few-body approaches underpredicted the experimental data of $^{27}$P. Our theoretical analysis shows that an enlarged core together with proton halo are probably the mechanism responsible for the enhancement of the cross sections for the reaction of $^{27}$P+$^{28}$Si.Comment: 16 pages, 5 figures, to be published in Phys.Rev.

Observation of in-gap surface states in the Kondo insulator SmB6 by photoemission

Kondo insulators (KIs) are strongly correlated materials in which the interactions between 4f and conduction electrons lead to a hybridization gap opening at low temperature 1-2. SmB6 is a typical KI, but its resistivity does not diverge at low temperatures, which was attributed to some in-gap states 3-10. However after several decades of research, the nature and origin of the in-gap states remain unclear. Recent band calculation and transport measurements suggest that the in-gap states could actually be ascribed to topological surface states. SmB6 thus might be the first realization of topological Kondo insulator (TKI) 13, the strongly correlated version of topological insulator (TI) 11,12. Here by performing angle-resolved photoemission spectroscopy (ARPES), we directly observed several dispersive states within the hybridization gap of SmB6, which cross the Fermi level and show negligible kz dependence, indicative of their surface origin. Furthermore, the circular dichroism (CD) ARPES results of the in-gap states suggest the chirality of orbital momentum, and temperature dependent measurements have shown that the in-gap states vanish simultaneously with the hybridization gap around 150 K. These strongly suggest their possible topological origin.Comment: 18 pages, 8 figure