Doping of graphene by a Au(111) substrate: Calculation strategy within the local density approximation and a semiempirical van der Waals approach

We have performed a density functional study of graphene adsorbed on Au(111) surface using both a local density approximation and a semiempirical van der Waals approach proposed by Grimme, known as the DFT-D2 method. Graphene physisorbed on metal has the linear dispersion preserved in the band-structure, but the Fermi level of the system is shifted with respect to the conical points which results in a doping effect. We show that the type and amount of doping depends not only on the choice of the exchange-correlation functional used in the calculations, but also on the supercell geometry that models the physical system. We analyzed how the factors such as the in-plane cell parameter and interlayer spacing in gold influence the Fermi level shift and we found that even a small variation in these parameters may cause a transition from p-type to n-type doping. We have selected a reasonable set of model parameters and obtained that graphene is either undoped or at most slightly p-type doped on the clean Au(111) surface, which seems to be in line with experimental findings. On the other hand, modifications of the substrate lattice may induce larger doping up to 0.30-0.40 eV depending on the graphene-metal adsorption distance. The sensitivity of the graphene-gold interface to the structural parameters may allow to tune doping across the samples which could lead to possible applications in graphene-based electronic devices. We believe that the present remarks can be also useful for other studies based on the periodic DFT

Energy gap tuning in graphene on hexagonal boron nitride bilayer system

We use a tight binding approach and density functional theory calculations to study the band structure of graphene/hexagonal boron nitride bilayer system in the most stable configuration. We show that an electric field applied in the direction perpendicular to the layers significantly modifies the electronic structure of the whole system, including shifts, anticrossing and other deformations of bands, which can allow to control the value of the energy gap. It is shown that band structure of biased system may be tailored for specific requirements of nanoelectronics applications. The carriers' mobilities are expected to be higher than in the bilayer graphene devices.Comment: 10 pages, 7 figures, submitted to Physical Review

Domains of doping in graphene on polycrystalline gold: first-principles and scanning tunneling spectroscopy studies

We have studied the graphene/gold interface by means of density functional theory (DFT) and scanning tunneling spectroscopy (STS). Weak interaction between graphene and the underlying gold surface leaves unperturbed Dirac cones in the band-structure, but they can be shifted with respect to the Fermi level of the whole system, which results in effective doping of graphene. DFT calculations revealed that the interface is extremely sensitive to the adsorption distance and to the structure of metal's surface, in particular strong variation in doping can be attributed to the specific rearrangements of substrate's atoms, such as the change in the crystallographic orientation, relaxation or other modifications of the surface. On the other hand, STS experiments have shown the presence of energetic heterogeneity in terms of the changes in the local density of states (LDOS) measured at different places on the sample. Randomly repeated regions of zero-doping and p-type doping have been identified from parabolic shape characteristics and from well defined Dirac points, respectively. The doping domains of graphene on gold seem to be related to the presence of various types of the surface structure across the sample. DFT simulations for graphene interacting with Au have shown large differences in doping induced by considered structures of substrate, in agreement with experimental findings. All these results demonstrate the possibility of engineering the electronic properties of graphene, especially tuning the doping across one flake which can be useful for applications of graphene in electronic devices

Painful skin eruption in a professional auto mechanic — a quiz

-A 37-year-old man, auto mechanic by trade, presented with multiple facial skin lesions, accompanied by burning sensation and pain, eye redness, fever and fatigue. The symptoms occurred 4 days before admission. Two weeks earlier he was consulted dermatologically due to hand eczema treated subsequently with topical steroids; additionally, he reported presence of concomitant facial erythema with scaling. Besides, the personal and familial medical history was unremarkable. Clinical examination revealed multiple skin erosions covered with serosanguineous crust, disseminated on his face, hands and forearms (Fig. 1); increased body temperature of 38.7 degrees Celsius, and conjunctival congestion. Laboratory tests revealed increased level of inflammatory parameters (C-reactive protein 21.25 mg/L, leukocytosis 13.48 ×109/L)

Influence of in ovo prebiotic and synbiotic administration on meat quality of broiler chickens

ABSTRACT A trial was conducted to evaluate the effect of in ovo injection of prebiotic and synbiotics on growth performance, meat quality traits (cholesterol content, intramuscular collagen properties, fiber measurements), and the presence of histopathological changes in the pectoral muscle (PS) of broiler chickens. On d 12 of incubation, 480 eggs were randomly divided into 5 experimental groups treated with different bioactives, in ovo injected: C, control with physiological saline; T1 with 1.9 mg of raffinose family oligosaccharides; T2 and T3 with 1.9 mg of raffinose family oligosaccharides enriched with different probiotic bacteria, specifically 1,000 cfu of Lactococcus lactis ssp. lactis SL1 and Lactococcus lactis ssp. cremoris IBB SC1, respectively; T4 with commercially available synbiotic Duolac, containing 500 cfu of both Lactobacillus acidophilus and Streptococcus faecium with the addition of lactose (0.001 mg/embryo). Among the hatched chickens, 60 males were randomly chosen (12 birds for each group) and were grown to 42 d in collective cages (n = 3 birds in each 4 cages: replications for experimental groups). Broilers were fed ad libitum commercial diets according to age. In ovo prebiotic and synbiotic administration had a low effect on investigated traits, but depend on the kind of bioactives administered. Commercial synbiotic treatment (T4) reduced carcass yield percentage, and the feed conversion ratio was higher in T3 and T4 groups compared with other groups. The abdominal fat, the ultimate pH, and cholesterol of the PS were not affected by treatment. Broiler chickens of the treated groups with both slightly greater PS and fiber diameter had a significantly lower amount of collagen. The greater thickness of muscle fibers (not significant) and the lower fiber density (statistically significant), observed in treated birds in comparison with those of the C group, are not associated with histopathological changes in the PS of broilers. The incidence of histopathological changes in broiler chickens from examined groups was low, which did not affect the deterioration of meat quality obtained from these birds

Dermoscopic Features of Giant Molluscum Contagio Contagiosum in a Patient with Acquired Immunodeficiency Syndrome

Giant molluscum contagiosum (MC) is a peculiar variant of the disease with the presence of multiple or single lesions larger than 5 mm. In contrast to typical molluscum contagiosum, dermoscopic features of giant lesions have been poorly described, and none of the reports included multiple giant lesions in an immunocompromised patient. We present a patient with acquired immunodeficiency syndrome diagnosed with multiple giant molluscum contagiosum along with the dermoscopic features of this entity

Videodermoscopy in the Assessment of Patients with Ocular Demodicosis

Introduction: There is growing evidence of the potential uses of dermoscopy in diagnostics of demodicosis. No previous studies have analyzed dermoscopic features in patients with ocular demodicosis. Objectives: To evaluate the potential usefulness of videodermoscopy in diagnostics of ocular demodicosis. Methods: It was a single-center prospective observational study in which results of videodermoscopic examination of the eyelids were compared to the results of classic microscopic examination in patients with suspected ocular demodicosis and healthy volunteers. Results: Study group included 16 women and 15 men. In fifteen (48.4%) patients, microbiological examination of epilated eyelashes was positive. The results of forms filled by the patients concerning known subjective clinical symptoms of ocular demodicosis revealed no significant differences between the group with positive and negative results of microscopic examination. The presence of Demodex tails and madarosis observed during dermoscopic assessment correlated positively with positive results of microscopic examination. At least one Demodex tail was found in 86.7% (13/15) cases with positive results of microscopic examination. In the two remaining cases microscopic evaluation showed the presence of Demodex brevis. In 37.5% (6/16) of patients with negative results of microscopic examination, videodermoscopy showed the presence of Demodex tails. Conclusions: Videodermoscopy may facilitate the diagnostics of ocular demodicosis. Patients reporting clinical symptoms suggesting ocular demodicosis but negative results of videodermoscopic examination should be referred to classical microscopic examination to exclude the presence of Demodex brevis. In patients with negative microscopic examination results and symptoms suggesting ocular demodicosis, dermoscopy-guided microscopic re-evaluation could be considered

Role of Spin-Orbit Coupling in the Electronic Structure of IrO₂

The delicate interplay of electronic charge, spin, and orbital degrees of freedom is in the heart of many novel phenomena across the transition metal oxide family. Here, by combining high- resolution angle resolved photoemission spectroscopy and first principles calculations (with and without spin-orbit coupling), the electronic structure of the rutile binary iridate, IrO$_2$ is investigated. The detailed study of electronic bands measured on a high-quality single crystalline sample, and use of a wide range of photon energy provide a huge improvement over the previous studies. The excellent agreement between theory and experimental results shows that the single-particle DFT description of IrO$_2$ band structure is adequate, without the need of invoking any treatment of correlation effects. Although many observed features point to a 3D nature of the electronic structure, clear surface effects are revealed. The discussion of the orbital character of the relevant bands crossing the Fermi level sheds light on spin orbit coupling-driven phenomena in this material, unveiling a spin-orbit induced avoided crossing, a property likely to play key role in its large spin Hall effect

Dermoscopy of Infectious Dermatoses (Infectiouscopy) in Skin of Color—A Systematic Review by the International Dermoscopy Society “Imaging in Skin of Color” Task Force

Dermoscopy has been showed to facilitate the non-invasive recognition of several infectious disorders (infectiouscopy) thanks to the detection of peculiar clues. Although most of the knowledge on this topic comes from studies involving light-skinned patients, there is growing evidence about its use also in dark phototypes. This systematic literature review summarizes published data on dermoscopy of parasitic, bacterial, viral and fungal dermatoses (dermoscopic findings, used setting, pathological correlation, and level of evidence of studies) and provides a homogeneous terminology of reported dermoscopic features according to a standardized methodology. A total of 66 papers addressing 41 different dermatoses (14 bacterial, 5 viral, 11 fungal infections, and 11 parasitoses/bites and stings) and involving a total of 1096 instances were included in the analysis. The majority of them displayed a level of evidence of V (44 single case reports and 21 case series), with only 1 study showing a level of evidence of IV (case-control analysis). Moreover, our analysis also highlighted a high variability in the terminology used in the retrieved studies. Thus, although promising, further studies designed according to a systematic and standardized approach are needed for better characterization of dermoscopy of infectious skin infections

Dermoscopy of Hair and Scalp Disorders (Trichoscopy) in Skin of Color—A Systematic Review by the International Dermoscopy Society “Imaging in Skin of Color” Task Force

Hair and scalp disorders are of significant interest for physicians dealing with dark phototypes due to their prevalence and potential aesthetic impact resulting from a higher tendency for scarring. In order to facilitate their non-invasive diagnosis, several dermoscopic studies have been published, yet data are sparse and no systematic analysis of the literature has been performed so far. This systematic literature review summarizes published data on trichoscopy of hair and scalp diseases (trichoscopic findings, used setting, pathological correlation, and level of evidence of studies). A total of 60 papers addressing 19 different disorders (eight non-cicatricial alopecias, nine cicatricial alopecias, and two hair shaft disorders) were assessed, for a total of 2636 instances. They included one cross-sectional analysis, 20 case-control studies, 25 case-series, and 14 single case-reports, so the level of evidence was V and IV in 65% and 33% of cases, respectively, with only one study showing a level of evidence of III. Notably, although there is a considerable body of literature on trichoscopy of hair/scalp diseases, our review underlined that potentially significant variables (e.g., disease stage or hair texture) are often not taken into account in published analyses, with possible biases on trichoscopic patterns, especially when it comes to hair shaft changes. Further analyses considering all such issues are therefore needed