Analysis of differential expression of tight junction proteins in cultured oral epithelial cells altered by Porphyromonas gingivalis,Porphyromonas gingivalis lipopolysaccharide,and extracellular adenosine triphosphate

Tight junctions （TJs） are the most apical intercellular junctions of epithelial cells formed by occludin, claudins, junctional adhesion molecules （JAMs）, and zonula occludens （ZO）. Tight junction proteins can sense the presence of bacteria and regulate the transcription of target genes that encode effectors and regulators of the immune response. The aim of this study was to determine the impact of TJ proteins in response to Porphyromonas gingivalis （P. gingivalis）, P. gingivalis lipopolysaccharide （P. gingivalis LPS）, and extracellular adenosine triphosphate （ATP） in the oral epithelial cell culture model. Quantified real time- polymerase chain reaction （RT-PCR）, immunoblots, and immunostaining were performed to assess the gene and protein expression in TJs. It was found that P. gingivalis infection led to transient upregulation of the genes encoding occludin, claudin- 1, and claudin-4 but not JAM-A, claudin-15, or ZO-1, while P. gingivalis LPS increased claudin-1, claudin-15, and ZO-1 and decreased occludin, JAM-A, and claudin-4. Tight junction proteins showed significant upregulation in the above two groups when cells were pretreated with ATP for 3 h. The findings indicated that P. gingivalis induced the host defence responses at an early stage. P. gingivalis LPS exerted a more powerful stimulatory effect on the disruption of the epithelial barrier than P. gingivalis. ATP stimulation enhanced the reaction of TJ proteins to P. gingivalis invasion and LPS destruction of the epithelium.

High-resolution ARPES endstation for in situ electronic structure investigations at SSRF

Angle-resolved photoemission spectroscopy(ARPES)is one of the most powerful experimental techniques in condensed matter physics.Synchrotron ARPES,which uses photons with high flux and continuously tunable energy,has become particularly important.However,an excellent synchrotron ARPES system must have features such as a small beam spot,super-high energy resolution,and a user-friendly operation interface.A synchrotron beamline and an endstation(BL03 U)were designed and constructed at the Shanghai Synchrotron Radiation Facility.The beam spot size at the sample position is 7.5(V)μm×67(H)μm,and the fundamental photon range is 7-165 eV;the ARPES system enables photoemission with an energy resolution of 2.67 meV at21.2 eV.In addition,the ARPES system of this endstation is equipped with a six-axis cryogenic sample manipulator(the lowest temperature is 7 K)and is integrated with an oxide molecular beam epitaxy system and a scanning tunneling microscope,which can provide an advanced platform for in situ characterization of the fine electronic structure of condensed matter.

Electronic structure of single-crystalline graphene grown on Cu/Ni(111) alloy film

Graphene with a Dirac cone-like electronic structure has been extensively studied because of its novel transport properties and potential application for future electronic devices.For epitaxially grown graphene,the process conditions and the microstructures are strongly dependent on various substrate materials with different lattice constants and interface energies.Utilizing angle-resolved photoemission spectroscopy,here we report an investigation of the electronic structure of single-crystalline graphene grown on Cu/Ni(111)alloy film by chemical vapor deposition.With a relatively low growth temperature,graphene on Cu/Ni(111)exhibits a Dirac cone-like dispersion comparable to that of graphene grown on Cu(111).The linear dispersions forming Dirac cone are as wide as 2 e V,with the Fermi velocity of approximately 1.1×10^6 m/s.Dirac cone opens a gap of approximately 152 meV at the binding energy of approximately 304 meV.Our findings would promote the study of engineering of graphene on different substrate materials.

Growth of high-quality perovskite (110)-SrIrO_3 thin films using reactive molecular beam epitaxy

Recently, 5d transition metal iridates have been reported as promising materials for the manttfacture of exotic quan- tum states. Apart from the semimetallic ground states that have been observed, perovskite SrlrO3 is also predicted to have a lattice-symmetrically protected topological state in the （110） plane due to its strong： spin-orbil coupling and electron correlation. Compared with non-polar （001）-SflrO3, the especial polarity of （110）-SrIrC）3 undoubtedly adds the： difficulty of fabrication and largely impedes the research on its surface states. Here, we have successfully synthesized high-quality （110）-SflrO3 thin films on （110）-SrTiO3 substrates by reactive molecular beam epitaxy fi^r the first time. Both reflec- tion high-energy electron diffraction pattems and x-ray diffraction measurements suggest the expected orientation and outstanding crystallinity. A （1 × 2） surface reconstruction driven from the surface instabiJity, the. same as that reported in （110）-SrTiO3, is observed. The electric transport measurements uncover that （110）-SrIrO3 exhibits a more prominent semimetallic property in comparison to （001）-SrIrO3.

Investigation of the room-temperature photoelectron spectroscopy of type-Ⅱ Weyl semimetal candidate WTe_(2)

Layered transition metal dichalcogenides have novel physical properties and great potential for applications.Among them,WTe2,which has an extremely large unsaturated magnetoresistance and is theoretically predicted to be a type-Ⅱ Weyl semimetal,has been extensively studied.Here,we systematically probe the electronic structure of WTe_(2) at room temperature using high-resolution angle-resolved photoelectron spectroscopy(ARPES).We find that temperature-driven chemical potential shift and Lifshitz transition,which is equivalent to low-energy band structures shift downward by around 50 meV,compared to the results at low temperatures.Our ARPES experimental results match well with previous theoretical calculations,implying the possible existence of type-Ⅱ Weyl points near the Γ-X axis.Also,as expected,there exists a dominantly electron-like Fermi surface instead of the one with compensated electrons and holes.Meanwhile,our ARPES results show that the flat band(FB) lying below the Fermi level(EF) becomes closer to the Fermi level at room temperature,which might start to dominate the transport behavior and lead to the disappearance of the unsaturated giant magnetoresistance effect.These findings not only reveal the electronic structure features of WTe_(2) at room temperature,but also provide new insights into the development of room-temperature topological quantum devices.