Sofia University

About: Sofia University is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Large Hadron Collider & Laser. The organization has 8533 authors who have published 15730 publications receiving 306320 citations. The organization is also known as: University of Sofia & BFUS.

Age-specific changes in the molecular phenotype of patients with moderate-to-severe atopic dermatitis.

Abstract: Background Atopic dermatitis (AD) shows differential clinical presentation in older compared with younger patients. Nevertheless, changes in the AD molecular profile with age are unknown. Objective We sought to characterize age-related changes in the AD profile. Methods We evaluated age-specific changes in lesional and nonlesional tissues and blood from patients with moderate-to-severe AD (n = 246) and age-matched control subjects (n = 71) using immunohistochemistry, quantitative real-time PCR, and Singulex in a cross-sectional study. Patients were analyzed by age group (18-40, 41-60, and ≥61 years). Results Although disease severity/SCORAD scores were similar across AD age groups (mean, approximately 60 years; P = .873), dendritic cell infiltrates (CD1b+ and FceRI+, P Conclusion The adult AD profile varies with age. Although TH1/TH17 skewing increases in both patients with AD and control subjects, patients with AD show unique decreases in TH2/TH22 polarization and normalization of epithelial abnormalities. Thus age-specific treatment approaches might be beneficial for AD.

Simulation of a quantum phase transition of polaritons with trapped ions

Abstract: We present a system for the simulation of quantum phase transitions of collective internal qubit and phononic states with a linear crystal of trapped ions. The laser-ion interaction creates an energy gap in the excitation spectrum, which induces an effective phonon-phonon repulsion and a Jaynes-Cummings-Hubbard interaction. This system shows features equivalent to phase transitions of polaritons in coupled cavity arrays. Trapped ions allow for easy tuning of the hopping frequency by adjusting the axial trapping frequency and the phonon-phonon repulsion via laser detuning and intensity. We propose an experimental protocol to access all observables of the system, which allows one to obtain signatures of the quantum phase transitions even with a small number of ions.

Measurement of surface tension by pulling a sphere from a liquid

Abstract: A new method for determination of the surface tension by measuring the maximum weight at the pull of a small vitreous sphere from the liquid is proposed The exact solution of the problem is found and is shown how the wetting of the sphere must be taken into account through the central angle formed between the sphere radius passing through the perimeter of wetting and the horizontal surface. A set for measuring the maximum weight and the central angle is described. The accuracy of determination of the surface tension and of the angle of wetting is estimated to be thousandths of dyn/cm and a few minutes, respectively. Some limitations of the method are discussed as well as the possibilities to overcome them. Various approximate solutions are treated and, in particular, it has been shown that the approximation previously used in the flotation model is satisfactorily accurate in that case.

Towards large-scale in free-standing graphene and N-graphene sheets

Abstract: One of the greatest challenges in the commercialization of graphene and derivatives is production of high quality material in bulk quantities at low price and in a reproducible manner. The very limited control, or even lack of, over the synthesis process is one of the main problems of conventional approaches. Herein, we present a microwave plasma-enabled scalable route for continuous, large-scale fabrication of free-standing graphene and nitrogen doped graphene sheets. The method’s crucial advantage relies on harnessing unique plasma mechanisms to control the material and energy fluxes of the main building units at the atomic scale. By tailoring the high energy density plasma environment and complementarily applying in situ IR and soft UV radiation, a controllable selective synthesis of high quality graphene sheets at 2 mg/min yield with prescribed structural qualities was achieved. Raman spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Near Edge X-ray-absorption fine-structure spectroscopy were used to probe the morphological, chemical and microstructural features of the produced material. The method described here is scalable and show a potential for controllable, large-scale fabrication of other graphene derivatives and promotes microwave plasmas as a competitive, green, and cost-effective alternative to presently used chemical methods.

Quaternionic Contact Einstein Structures and the Quaternionic Contact Yamabe Problem

Abstract: A partial solution of the quaternionic contact Yamabe problem on the quaternionic sphere is given. It is shown that the torsion of the Biquard connection vanishes exactly when the trace-free part of the horizontal Ricci tensor of the Biquard connection is zero and this occurs precisely on 3-Sasakian manifolds. All conformal transformations sending the standard flat torsion-free quaternionic contact structure on the quaternionic Heisenberg group to a quaternionic contact structure with vanishing torsion of the Biquard connection are explicitly described. A `3-Hamiltonian form' of infinitesimal conformal automorphisms of quaternionic contact structures is presented.