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There has been a long-standing debate about the mechanism of the unusual superconductivity in alkali-intercalated fulleride superconductors. In this work, using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the electronic structures of superconducting K3C60 thin films. We observe a dispersive energy band crossing the Fermi level with an occupied bandwidth of about 130 meV. The measured band structure shows prominent quasiparticle kinks and a replica band involving high-energy Jahn-Teller active Hg(8) phonon mode, reflecting strong electron-phonon coupling in the system. The electron-phonon coupling constant is estimated to be about 1.2, which dominates the quasiparticle mass renormalization. Moreover, we observe an isotropic nodeless superconducting gap beyond the mean-field estimation. Both the large electron-phonon coupling constant and large reduced superconducting gap suggest a strong-coupling superconductivity in K3C60, while the electronic correlation effect is indicated by the observation of a waterfall-like band dispersion and the small bandwidth compared with the effective Coulomb interaction. Our results not only directly visualize the crucial band structure of superconducting fulleride but also provide important insights into the mechanism of the unusual superconductivity., Accepted by Phys. Rev. Lett

EuTe4 is a newly-discovered van der Waals material exhibiting a novel charge-density wave (CDW) with a large thermal hysteresis in the resistivity and CDW gap. In this work, we systematically study the electronic structure and transport properties of EuTe4 using high-resolution angle-resolved photoemission spectroscopy (ARPES), magnetoresistance measurements, and scanning tunneling microscopy (STM). We observe a CDW gap of about 200 meV at low temperatures that persists up to 400 K, suggesting that the CDW transition occurs at a much higher temperature. We observe a large thermal hysteretic behavior of the ARPES intensity near the Fermi level, consistent with the resistivity measurement. The hysteresis in the resistivity measurement does not change under a magnetic field up to 7 T, excluding the thermal magnetic hysteresis mechanism. Instead, the surface topography measured with STM shows surface domains with different CDW trimerization directions, which may be important for the thermal hysteretic behavior of EuTe4. Interestingly, we observe a large negative magnetoresistance at low temperatures that can be associated with the canting of magnetically ordered Eu spins. Our work shed light on the understanding of magnetic, transport, and electronic properties of EuTe4.

Angle-resolved photoemission spectroscopy with sub-micrometer spatial resolution ({\mu}-ARPES), has become a powerful tool for studying quantum materials. To achieve sub-micrometer or even nanometer-scale spatial resolution, it is important to focus the incident light beam (usually from the synchrotron radiation) using X-ray optics such as the zone plate or ellipsoidal capillary mirrors. Recently, we developed a laser-based {\mu}-ARPES with spin-resolution (LMS-ARPES). The 177 nm laser beam is achieved by frequency doubling a 355 nm beam using a KBBF crystal and subsequently focused using an optical lens with a focal length of about 16 mm. By characterizing the focused spot size using different methods and performing spatial-scanning photoemission measurement, we confirm the sub-micron spatial resolution of the system. Compared with the {\mu}-ARPES facilities based on synchrotron radiation, our LMS-ARPES system is not only more economical and convenient but also with higher photon flux (> 5E13 photons/s), thus enabling the high-resolution and high-statistics measurements. Moreover, the system is equipped with a two-dimensional spin detector based on exchange scattering at a surface-passivated iron film grown on a W(100) substrate. We investigate the spin structure of the prototype topological insulator Bi2Se3 and reveal a high spin-polarization rate, confirming its spin-momentum locking property. This lab-based LMS-ARPES will be a powerful research tool for studying the local fine electronic structures of different condensed matter systems, including topological quantum materials, mesoscopic materials and structures, and phase-separated materials., Comment: To appear in RSI

Recently, magnetic topological quantum materials have attracted substantial research attention due to their great application potential. Here, using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation, we systematically investigate the electronic structure of antiferromagnet Dirac semimetal candidate GdIn3. According to our ab initio calculation, there exist two and one pair(s) of Dirac fermions in the paramagnetic and antiferromagnetic state, respectively. In the antiferromagnetic state, the magnetic Dirac semimetal phase is protected by C4z rotation symmetry in the type-IV magnetic space group. Our experiment above the Néel temperature is well reproduced by the calculated band structure in the paramagnetic state, from which we identify a pair of Dirac fermions at 1.5 eV below the Fermi level. However, we do not observe the signature of electronic reconstruction in the antiferromagnetic state, suggesting a weak interaction between the localized Gd 4f states of spin configuration S=7/2μB and the itinerant conduction electrons. Our results confirm the Dirac semimetal nature of the paramagnetic GdIn3 and provide important insights into its antiferromagnetic Dirac semimetal phase.

Hydrophilic 2,3-dimercaptosuccinnic acid (HOOC-CH(SH)-CH(SH)-COOH, DMSA) coated monodisperse magnetic nanoparticles (Fe3O4) were dispersed in water, RPMI-1640 with 10% (v/v) fetal calf serum, RPMI-1640, PBS and MES, respectively, to investigate their stability under biologically relevant conditions. The Photon Correlation Spectroscopy (PCS) results showed that DMSA-Fe3O4 nanoparticles existed as aggregate under biological conditions. UV-vis, MRI and AFM results indicated that DMSA-Fe3O4 nanoparticles dispersed in RPMI-1640, PBS and MES presented poor stability, whereas those dispersed in RPMI-1640 with fetal calf serum exhibited excellent stability, which was due to their adsorption from fetal calf serum, as confirmed by zeta potential and IR results. Additionally, in vitro cell experiments showed that DMSA-Fe3O4 nanoparticles with adsorption from fetal calf serum had higher intracellular uptake than those without adsorption from serum, indicating that fetal calf serum could play a great role in intracellular uptake of nanoparticles.

A study was carried out on the chromosomes of periodic Brugia malayi using air drying preparations of testis, ovary and uterus. The results showed that the oogonial metaphase consisted of 4 pairs of small-sized autosomes and one pair of large-sized sex-chromosomes, that the spermatogonial metaphase consisted of 4 pairs of small-sized autosomes and one large-sized and one medium-sized sex-chromosome, the oocytes at diakinesis had 5 bivalents, the secondary spermatocytes 5 univalents and the fertilized eggs 10 chromosomes. The above-mentioned findings revealed that the chromosome number was 2n = 10 and that the sex-determining mechanism was of the XY-XX type in this type of B. malayi.

A new kind of flow-through sensor for atropine has been studied. It exhibits Nernstian response for atropine with a slope of 54 +/- 1 mV/decade over the concentration range of 0.02-200 mmol/L at pH 5-8. The sensitivity coefficients of common compounds were determined. Only bromo-geramine, clonidine, strychnine and amantadine showed remarkable interference. Direct potentiometry for determination of atropine showed an average recovery of 99.2% and a relative standard deviation of 1.3%. It has been used in flow injection analysis (FIA) of atropine, anisodamine and scopolamine and belladonna preparations. Rate of analysis of as high as 60-100 samples/h was achieved.