Optical spectroscopy study of Nd(O,F)BiS2 single crystals

We present an optical spectroscopy study on F-substituted NdOBiS$_2$ superconducting single crystals grown using KCl/LiCl flux method. The measurement reveals a simple metallic response with a relatively low screened plasma edge near 5000 \cm. The plasma frequency is estimated to be 2.1 eV, which is much smaller than the value expected from the first-principles calculations for an electron doping level of x=0.5, but very close to the value based on a doping level of 7$\%$ of itinerant electrons per Bi site as determined by ARPES experiment. The energy scales of the interband transitions are also well reproduced by the first-principles calculations. The results suggest an absence of correlation effect in the compound, which essentially rules out the exotic pairing mechanism for superconductivity or scenario based on the strong electronic correlation effect. The study also reveals that the system is far from a CDW instability as being widely discussed for a doping level of x=0.5.Comment: 5 pages, 5 figure

Tunable cavity coupling of the zero phonon line of a nitrogen-vacancy defect in diamond

We demonstrate the tunable enhancement of the zero phonon line of a single nitrogen-vacancy color center in diamond at cryogenic temperature. An open cavity fabricated using focused ion beam milling provides mode volumes as small as 1.24 $\mu$m$^3$. In-situ tuning of the cavity resonance is achieved with piezoelectric actuators. At optimal coupling of the full open cavity the signal from individual zero phonon line transitions is enhanced by about a factor of 10 and the overall emission rate of the NV$^-$ center is increased by 40% compared with that measured from the same center in the absence of cavity field confinement. This result is important for the realization of efficient spin-photon interfaces and scalable quantum computing using optically addressable solid state spin qubits.Comment: 11 pages Main Article + 4 pages Supplementary Info Typos fixed from v

Nitrogen dynamics in the shallow groundwater of a riparian wetland zone of the Garonne, SW France: nitrate inputs, bacterial densities, organic matter supply and denitrification measurements

This study highlights the role of interactions between surface and sub-surface water of the riparian zone of a large river (the Garonne, SW France). Information is given about the role of surface water in supplying Dissolved Organic Carbon (DOC ) to the riparian zone for nitrate removal processes. The densities of bacteria (up to 3.3106 cell m L-1) in groundwater are strongly conditioned by the water moving during flood events. Total bacterial densities in groundwater were related to surface water bacterial densities. In sediment, total bacteria are attached mainly to fine particles (90 % in the fraction < 1 mm). Spatial variations in organic carbon and nitrate content in groundwater at the site studied are correlated with exchanges between the groundwater and the river, from the upstream to the downstream part of the meander. Total bacterial densities, nitrate and decressing organic carbon concentrations follow the same pattern. These results suggest that, in this kind of riparian wetland, nitrate from alluvial groundwater influenced by agricultural practices may be denitrified by bacteria in the presence of organic carbon from river surface water

Magnetic Incommensurability in Doped Mott Insulator

In this paper we explore the incommensurate spatial modulation of spin-spin correlations as the intrinsic property of the doped Mott insulator, described by the $t-J$ model. We show that such an incommensurability is a direct manifestation of the phase string effect introduced by doped holes in both one- and two-dimensional cases. The magnetic incommensurate peaks of dynamic spin susceptibility in momentum space are in agreement with the neutron-scattering measurement of cuprate superconductors in both position and doping dependence. In particular, this incommensurate structure can naturally reconcile the neutron-scattering and NMR experiments of cuprates.Comment: 12 pages (RevTex), five postscript figure

Effect of different implant placement depths on crestal bone levels and soft tissue behavior: A 5â year randomized clinical trial

ObjectivesThis randomized clinical trial analyzed the longâ term (5â year) crestal bone changes and soft tissue dimensions surrounding implants with an internal tapered connection placed in the anterior mandibular region at different depths (equiâ and subcrestal).Materials and methodsEleven edentulous patients were randomly divided in a splitâ mouth design: 28 equicrestal implants (G1) and 27 subcrestal (1â 3 mm) implants (G2). Five implants were placed per patient. All implants were immediately loaded. Standardized intraoral radiographs were used to evaluate crestal bone (CB) changes. Patients were assessed immediately, 4, 8, and 60 months after implant placement. The correlation between vertical mucosal thickness (VMT) and soft tissue recession was analyzed. Subâ group analysis was also performed to evaluate the correlation between VMT and CB loss. Rankâ based ANOVA was used for comparison between groups (α = .05).ResultsFiftyâ five implants (G1 = 28 and G2 = 27) were assessed. Implant and prosthetic survival rate were 100%. Subcrestal positioning resulted in less CB loss (â 0.80 mm) when compared to equicrestal position (â 0.99 mm), although the difference was not statistically significant (p > .05). Significant CB loss was found within the G1 and G2 groups at two different measurement times (T4 and T60) (p  .05).ConclusionsThere was no statistically significant difference in CB changes between subcrestal and equicrestal implant positioning; however, subcrestal position resulted in higher bone levels. Neither mucosal recession nor vertical mucosa thickness was influenced by different implant placement depths.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154286/1/clr13569.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154286/2/clr13569_am.pd

Di-tert-butyl (2R,3R)-2-{[(2E)-3-(4-acet­yloxy-3-meth­oxy­phen­yl)prop-2-eno­yl]­oxy}-3-hy­droxy­butane­dioate

In the title mol­ecule, C24H32O10, one tert-butyl ester group is folded towards the central benzene ring while the other is directed away. The acetyl group is almost perpendicular to the benzene ring to which it is connected [C—C—O—C torsion angle = 90.4 (12)°]. The conformation about the ethene bond [1.313 (7) Å] is E. The atoms of the benzene ring and its attached ester group and part of the hy­droxy tert-butyl ester side chain are disordered over two sets of sites in a 50:50 ratio. Linear supra­molecular chains along the a axis mediated by hy­droxy–carbonyl O—H⋯O hydrogen bonds feature in the crystal packing. The same H atom also partakes in an intra­molecular O—H⋯O inter­action