Observation of an eg-derived metallic band at the Cs/SrTiO3 interface by polarization-dependent photoemission spectroscopy

International audienc

Peculiar bonding associated with atomic doping and hidden honeycombs in borophene

[[abstract]]Engineering atomic-scale structures allows great manipulation of physical properties and chemical processes for advanced technology. We show that the B atoms deployed at the centers of honeycombs in boron sheets, borophene, behave as nearly perfect electron donors for filling the graphitic σ bonding states without forming additional in-plane bonds by first-principles calculations. The dilute electron density distribution owing to the weak bonding surrounding the center atoms provides easier atomic-scale engineering and is highly tunable via in-plane strain, promising for practical applications, such as modulating the extraordinarily high thermal conductance that exceeds the reported value in graphene. The hidden honeycomb bonding structure suggests an unusual energy sequence of core electrons that has been verified by our high-resolution core-level photoelectron spectroscopy measurements. With the experimental and theoretical evidence, we demonstrate that borophene exhibits a peculiar bonding structure and is distinctive among two-dimensional materials.[[notice]]補正完

Symmetry-breaking and spin-blockage effects on carrier dynamics in single-layer tungsten diselenide

Understanding carrier creation and evolution in materials initiated by pulsed optical excitation is central to developing ultrafast optoelectronics. We demonstrate herein that the dynamic response of a system can be drastically modified when its physical dimension is reduced to the atomic scale, the ultimate limit of device miniaturization. A comparative study of single-layer (SL) tungsten diselenide(WSe2) relative to bulk WSe2 shows substantial differences in the transient response as measured by time- and angle-resolved photoemission spectroscopy (TRARPES). The conduction-band minimum in bulk WSe2, populated by optical pumping, decays promptly. The corresponding decay for SL WSe2 is much slower and exhibits two time constants. The results indicate the presence of two distinct decay channels in the SL that are correlated with the breaking of space inversion symmetry in the two-dimensional limit. This symmetry breaking lifts the spin degeneracy of the bands, which in turn causes the blockage of decay for one spin channel. The stark contrast between the single layer and the bulk illustrates the basic carrier scattering processes operating at different timescales that can be substantially modified by dimensional and symmetry-reduction effects

A role of methicillinresistant Staphylococcus aureus strains and related molecular genetic features in developing purulent-necrotic forms of the diabetic foot syndrome

Purulent-necrotic  complications in patients with diabetic foot syndrome is one of the main causes resulting in amputation and disability, or even lethal outcome. Our study was aimed at investigating a role played by MRSA and related molecular genetic features, as well as antibiotic resistance in developing purulent-necrotic forms of the diabetic foot syndrome in Krasnoyarsk, in the 2010–2016 period. A microbiota profile related to purulent-necrotic complications, antibiotic susceptibility, as well as the molecular genetic features of methicillin-resistant Staphylococcus aureus were examined in 240 patients with diabetic foot syndrome. A bacteriological method was used to investigate microbiota profile related to purulent complications. Antibiotic sensitivity was analyzed by disc-diffusion method; staphylococcal antibiotic sensitivity was evaluated by screening, PCR, solid medium serial dilution, in accordance with the CLSI and EUCAST international recommendations. Genotyping and examining molecular genetic features were performed by using PCR, M-PCR, and sequencing. The data were analyzed by using WHONET (WHO) software. Significance level was set at p <0.05. It was found that microbiota profile linked to purulent-necrotic forms of the diabetic foot syndrome was presented by various Gram-negative microorganisms including Enterobacteriaceae spp. and non-fermenting bacteria accounting for 34.4% and 19.1%, respectively, as well as Gram-positive microorganisms found in 46.5% cases, including S. aureus (18.4% cases). Moreover, microorganisms were characterized by multiresistance to diverse antimicrobial drugs: percent-age of BLDS- and MBL-producers as well as MRSA comprised 36.4%, 30.3%, and 36.4%, respectively. Further, MRSA ST239/spa3(t037)/agr1/SCCmecIII.1.1.2(IIIA)/coaIV/tst+  clone dominated in patients with purulent-necrotic  forms of diabetic foot syndrome admitted to the right-bank and left-bank hospitals in the city of Krasnoyarsk that was characterized by a high virulence level and multidrug resistance. Next, subdominant MRSA genetic variants were presented by ST8/spa1(t008)/agr1/SCCmecIV.3.1.1/CoaIII and ST12/spanew(t156)/agr1/SCCmecUT/coaIorVII characterized by resistance to 1–2 groups of antimicrobials apart from β-lactams. Importantly, similar MRSA genetic variants earlier isolated in patients with other nosological entities common in this geographic region were also mainly verified in patients with purulent-necrotic forms of diabetic foot syndrome admitted to Krasnoyarsk hospitals. In particular, it was demonstrated that MRSA isolates predominantly belonging to the same genetic variants were detected in patients with purulent-necrotic forms of diabetic foot syndrome hospitalized both at the right-bank and left-bank hospitals of the city of Krasnoyarsk. Thus, long-term hospitalization of patients with purulent-necrotic forms of diabetic foot syndrome as well as subsequent repeated admittance to other hospitals in the city of Krasnoyarsk facilitates inter-hospital bacterial strain transmission