Study on Anomalous Hall Effect and Spin-Orbit Torque Effect of TbCo-Based Multilayer Films.

The anomalous Hall effect and spin-orbit torque of TbCo-based multilayer films have been methodically studied in recent years. Many properties of the films can be obtained by the anomalous Hall resistance loops of the samples. We report on the effects of a structure composed of two heavy metals as the buffer layers on the anomalous Hall resistance loops of TbCo-based multilayers at different temperatures. The results showed that the coercivity increases dramatically with decreasing temperature, and the samples without perpendicular magnetic anisotropy at room temperature showed perpendicular magnetic anisotropy at low temperatures. We quantified the spin-orbit torque efficiency and Dzyaloshinskii-Moriya interaction effective field size of the films W/Pt/TbCo/Pt at room temperature by measuring the loop shift of anomalous Hall resistance. The results showed that the study of anomalous Hall resistance loops plays an important role in the study of spintronics, which can not only show the basic properties of the sample, but can also obtain other information about the sample through the shift of the loops.

A photo-degradable BODIPY-modified Ru(II) photosensitizer for safe and efficient PDT under both normoxic and hypoxic conditions.

Photodynamic therapy (PDT) is promising for cancer treatment but still suffers from some limitations. For instance, PDT based on 1O2 generation (in a type-II mechanism) is heavily dependent on high oxygen concentrations and will be significantly depressed in hypoxic tumors. In addition, the residual photosensitizers after PDT treatment may cause severe side-effects under light irradiation. To solve these problems, herein a BODIPY (boron dipyrromethene)-modified Ru(II) complex [Ru(dip)2(tpy-BODIPY)]2+ (complex 1, dip = 4,7-diphenyl-1,10-phenanthroline, tpy = 2,2':6',2''-terpyridine) was designed and synthesized. Complex 1 exhibited both high singlet oxygen quantum yield (Φ = 0.7 in CH3CN) and excellent superoxide radical (O2˙-) generation, and thus demonstrated efficient PDT activity under both normoxic and hypoxic conditions. Moreover, complex 1 is photo-degradable in water, and greatly loses its ROS generation ability after PDT treatment. These novel properties of complex 1 make it promising for efficient PDT under both normoxic and hypoxic conditions with reduced side-effects.

Nitroreductase-Responsive Photosensitizers for Selective Imaging and Photo-Inactivation of Intracellular Bacteria.

Intracellular Staphylococcus aureus (S. aureus), especially the methicillin resistant staphylococcus aureus (MRSA), are difficult to detect and eradicate due to the protection by the host cells. Antibacterial photodynamic therapy (aPDT) offers promise in treating intracellular bacteria, provided that selective damage to the bacteria ranther than host cells can be realized. According to the different nitroreductase (NTR) levels in mammalian cells and S. aureus, herein NTR-responsive photosensitizers (PSs) (T)CyI-NO2 were designed and synthesized. The emission and 1O2 generation of (T)CyI-NO2 are quenched by the 4-nitrobenzyl group, but can be specifically switched on by bacterial NTR. Therefore, selective imaging and photo-inactivation of intracellular S. aureus and MRSA were achieved. Our findings may pave the way for the development of more efficient and selective aPDT agents to combat intractable intracellular infections.

The effect of quenching and Mn substitution for Ni on the magnetic properties of Mn25+xNi50-xGa25.

Ni-Mn based Heusler alloys have attracted widespread attention due to their novel physical properties. However, the structure of Mn2NiGa is metastable at room temperature, making it difficult to obtain its intrinsic physical properties and limiting its application. In this study, we obtained Mn2NiGa by replacing Ni in the precursor alloy Ni2MnGa with Mn and studied its magnetic properties, structures, and phase transitions with floating composition. In addition, we focused on the compositional segregation characteristics of Mn2NiGa caused by different heat treatment and quenching conditions. It was found that the samples quenched after annealing at 773 K for 48 hours exhibited abnormalities in magnetism, phase transformation, and structure. The further electron probe scanning characterization results reveal that the changes in these physical properties were related to component segregation caused by heat treatment.

Ru(II) Complexes with Enaminone Structures for Rapid Sterilization of Staphylococcus aureus and MRSA with Little Accumulation of Drug Resistance.

Drug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), pose a serious threat to human life. Therefore, there is urgent need to develop antibiotics with new chemical structures and antibacterial mechanisms, especially those that elicit little drug resistance after long-term use. Herein we synthesized three novel ruthenium complexes (Ru1-Ru3) containing the enaminone structures for the first time. At a concentration of 5 µM, Ru1-Ru3 can lead to a CFU reduction of about 5 log units towards S. aureus and MRSA. Interestingly, Ru3 displayed rapid bactericidal effects and could decrease the CFU numbers of both pathogens by 5 log units within 40 min. The control compounds (Ru4 and Ru5) without the enaminone structures displayed very poor antibacterial activity under the same conditions. Moreover, S. aureus did not show apparent drug resistance towards Ru3 after 20 passages incubation with a sublethal concentration. These results highlight the critical role of enaminone structures for antibacterial applications.

The effect of Cr doping on the magnetic and magnetocaloric properties of Ni45Co5Mn36.5In13.5 Heusler alloys.

Herein, Ni45-xCrxCo5Mn36.5In13.5 (x = 0, 0.2, 0.4, and 0.6 at%) and Ni45Co5Mn36.5-yCryIn13.5 (y = 0.2, 0.4, and 0.6 at%) polycrystalline Heusler alloys are prepared by arc melting and then characterized using X-ray diffraction and a vibrating sample magnetometer. A single L21 austenitic phase is confirmed at room temperature. Meanwhile, we studied the effect of Cr doping on the magnetic properties of Ni45Co5Mn36.5In13.5 alloys. It is observed that, with the incorporation of Cr atoms, both the lattice constant and valence electron concentration of the alloys have changed, resulting in the phase transition temperature, saturation magnetization and magnetic entropy changing significantly. In addition, when Cr is replaced by Mn, the change of phase transition temperature (ΔT) induced by the magnetic field decreases; therefore, in the Ni45Co5Mn36.1Cr0.4In13.5 samples, the magnetic entropy change reaches a maximum value of up to 37.1 J kg-1 K-1 under an external magnetic field of 3T, which is more than 50% higher than that of other Ni-Mn based Heusler alloys reported in the literature.

In vitro and in vivo evaluation of brimonidine loaded silica nanoparticles-laden silicone contact lenses to manage glaucoma.

Glaucoma is treated by frequent instillation of 0.2% w/v brimonidine tartrate eye drop solution, which showed poor ocular bioavailability of 1-3%. Medicated contact lenses can be used to improve the ocular drug bioavailability. However, drug loading in the contact lens matrix showed high burst release and changes the optophysical properties of the contact lens material. In this paper, a novel brimonidine loaded silica nanoparticles-laden silicone contact lenses (Bri-Si) were designed to achieve controlled drug delivery without altering the optophysical properties of the contact lens. Silica nanoparticles were prepared by polymerizing octadecyltrimethoxysilane (OTMS) molecules at the oil/water interface of microemulsion. Traditional soaking method (Bri-SM), direct brimonidine-loading method (Bri-DL) and microemulsion-laden contact lens (Bri-ME) were developed for comparison. The Bri-Si lens showed improved swelling, transmittance, oxygen permeability and lysozyme adherence compared to Bri-SM, Bri-DL and Bri-ME lenses. The Bri-DL lens showed high brimonidine leaching during extraction and sterilization steps, with low cumulative drug release. While, Bri-Si lens show controlled brimonidine release for 144 h. In a rabbit tear fluid model, the Bri-Si lens showed high brimonidine concentration for 96 h compared to Bri-ME lens and eye drop therapy. Based on histopathological studies of cornea, the Bri-Si lens was found to be safe for human applications. The data demonstrated the novel application of silica nanoparticles to control brimonidine release from the contact lens without altering the optophysical properties of the contact lens.

Magnetically Powered Shape-Transformable Liquid Metal Micromotors.

Shape-transformable liquid metal (LM) micromachines have attracted the attention of the scientific community over the past 5 years, but the inconvenience of transfer routes and the use of corrosive fuels have limited their potential applications. In this work, a shape-transformable LM micromotor that is fabricated by a simple, versatile ice-assisted transfer printing method is demonstrated, in which an ice layer is employed as a "sacrificial" substrate that can enable the direct transfer of LM micromotors to arbitrary target substrates conveniently. The resulting LM microswimmers display efficient propulsion of over 60 µm s-1 (≈3 bodylength s-1 ) under elliptically polarized magnetic fields, comparable to that of the common magnetic micro/nanomotors with rigid bodies. Moreover, these LM micromotors can undergo dramatic morphological transformation in an aqueous environment under the irradiation of an alternating magnetic field. The ability to transform the shape and efficiently propel LM microswimmers holds great promise for chemical sensing, controlled cargo transport, materials science, and even artificial intelligence in ways that are not possible with rigid-bodies microrobots.

The relationship between the asymmetric magnetoresistive effect and the magnetocaloric effect in Ni43Co7Mn39-xCrxSn11 Heusler alloys.

The correlation between the magnetocaloric effect and magnetotransport property was investigated in Ni43Co7Mn39-xCrxSn11 Heusler alloys. The asymmetric isothermal-magnetoresistance around the phase transformation temperature was observed, from which a parameter γ, determined as the ratio of the asymmetric magnetoresistance to the temperature coefficient of resistance, is proposed. According to Maxwell's equation, the parameter γ is analyzed to be equivalent to the transformation temperature change induced by a magnetic field in martensitic transformation. This finding is confirmed by experimental results. In addition, the γ values can be used to estimate the magnetic entropy change of the martensitic transformation directly without measuring the comprehensive temperature dependence of magnetization curves.

Magnetically Powered Annelid-Worm-Like Microswimmers.

A bioinspired magnetically powered microswimmer is designed and experimentally demonstrated by mimicking the morphology of annelid worms. The structural parameters of the microswimmer, such as the surface wrinkling, can be controlled by applying prestrain on substrate for the precise fabrication and consistent performance of the microswimmers. The resulting annelid-worm-like microswimmers display efficient propulsion under an oscillating magnetic field, reaching a peak speed of ≈100 µm s-1 . The speed and directionality of the microswimmer can be readily controlled by changing the parameters of the field inputs. Additionally, it is demonstrated that the microswimmers are able to transport microparticles toward a predefined destination, although the translation velocity is inevitably reduced due to the additional hydrodynamic resistance of the microparticles. These annelid-worm-like microswimmers have excellent mobility, good maneuverability, and strong transport capacity, and they hold considerable promise for diverse biomedical, chemical sensing, and environmental applications.

[Population Status of Centropus sinensis in Guangxi Province].

OBJECTIVE: T0 understand the population distribution, species abundance and habitats requirement of a medicinal animal, Centropus sinensis, in Guangxi Province. METHODS: Line transect methods were used to census population number and habitat types in 18 counties or cities of Guangxi. RESULTS: Centropus sinensis distributed in all study area, with a higher population density in the south than in the north. Among seven habitat types, the species preferred living in forest-farmland ecotone, while seldom in broad-leaves forest or plantations. CONCLUSION: The results of habitat preference show an advantage to the population recovering for forest-farmland ecotone commonly existing in Guangxi Province. But the speed of population recovering is slowly under illegal hunting pressure. More attention should be paid to protect this species.