Mass-symmetry breaking in three-body ions

The ground-state energy of three-body ions $(M^+,M^+,m^-)$ evolves when the like-charge constituents are given different masses. The comparison of $(m_1^+,m_2^+,m^-)$ with the average of $(m_1^+,m_1^+,m^-)$ and $(m_2^+,m_2^+,m^-)$ reveals a competition between the symmetric term and the antisymmetric one. The former dominates in the Born--Oppenheimer regime such as the (p,t,e) case, while the latter wins for H$^-$-like systems with two negative light particles surrounding a heavy nucleus. A comparison is also made with the case of baryons in simple quark models with flavour independence.Comment: 4 pages, 3 figure

Constrains on non-Newtonian gravity from the experiment on neutron quantum states in the Earth's gravitational field

An upper limit to non-Newtonian attracive forces is obtained from the measurement of quantum states of neutrons in the Earth's gravitational field. This limit improves the existing constrains in the nanometer range

Ionization Potential of the Helium Atom

Ground state ionization potential of the He^4 atom is evaluated to be 5 945 204 221 (42) MHz. Along with lower order contributions, this result includes all effects of the relative orders alpha^4, alpha^3*m_e/m_alpha and alpha^5*ln^2(alpha).Comment: 4 page

Proton-electron mass ratio from HD+^+ revisited

We present a new derivation of the proton-electron mass ratio from the hydrogen molecular ion, HD$^+$. The derivation entails the adjustment of the mass ratio in highly precise theory so as to reproduce accurately measured ro-vibrational frequencies. This work is motivated by recent improvements of the theory, as well as the more accurate value of the electron mass in the recently published CODATA-14 set of fundamental constants, which justifies using it as input data in the adjustment, rather than the proton mass value as done in previous works. This leads to significantly different sensitivity coefficients and, consequently, a different value and larger uncertainty margin of the proton-electron mass ratio as obtained from HD$^+$

Relativistic corrections of order m\alpha^6 to the two-center problem

Effective potentials of the relativistic m\alpha^6 order correction for the ground state of the Coulomb two-center problem are calculated. They can be used to evaluate the relativistic contribution of that order to the energies of hydrogen molecular ions or metastable states of the antiprotonic helium atom, where precision spectroscopic data are available. In our studies we use the variational expansion based on randomly chosen exponents that permits to achieve high numerical accuracy.Comment: 12 pages, 3 tables 2 figures; submitted to the Journal of Physics

Why three-body physics do not solve the proton radius puzzle

The possible involvement of weakly bound three-body systems in the muonic hydrogen spectroscopy experiment [1], which could resolve the current discrepancy between determinations of the proton radius, is investigated. Using variational calculations with complex coordinate rotation, it is shown that the $p\mu e$ ion, which was recently proposed as a possible candidate [2], has no resonant states in the energy region of interest. QED level shifts are included phenomenologically by including a Yukawa potential in the three-body Coulomb Hamiltonian before diagonalization. It is also shown that the $pp\mu$ molecular ion cannot play any role in the observed line

Increasing the resistance of a NiCrBSi coating to heat wear by means of combined laser heat treatment

Testing of NiCrBSi coatings formed by gas-powder laser cladding and combined laser heat treatment, including laser cladding and high-temperature annealing, were conducted under conditions of sliding friction on the Kh12M steel according to the pin-on-disk scheme. The combined processing resulting in the formation of large carbides and chromium borides in the coatings is shown to increase their wear resistance by a factor of 1.8 at sliding velocities of 6.1 and 9.3 m/s, when there is significant frictional heating of the friction surfaces. © 2018 Author(s)

Relativistic and QED corrections to the 2pσu(υ=1)2p\sigma_{u}(\upsilon = 1) vibrational state of the H2+H^{+}_{2} molecular ion

Relativistic and QED corrections to the recently discovered first vibrational $2p\sigma_u$ state are presented. This state has an extremely small nonrelativistic binding energy $E_B=1.085045252(1)\times10^{-9}$ a.u. Its wave functions has a maximum at $R\approx100$ a.u. and extends up to several hundreds. It is shown that this state does not disappear if higher order relativistic and QED corrections, including the Casimir--Polder effect, are taken into account

Antibiotic sensitivity analysis of clinical coagulase-negative staphylococci

Background. The increasing role of coagulase-negative staphylococci in the occurrence of staphylococcal infections leads to the need for close attention to them. Special control is required over the sensitivity of bacteria to antibiotics and the spread of methicillin resistance, as a sign of multiple resistance to antibacterial drugs. It is also important to identify the virulence factors of coagulase-negative staphylococci, which determine their behavior in the environment.The aim. To evaluate the sensitivity of strains of coagulase-negative staphylococci to clinically significant antibiotics daptomycin, vancomycin, linezolid and oxacillin and lantibiotic warnerin.Methods. Determination of the minimal inhibitory concentrations of antibacterial compounds for clinical coagulase-negative staphylococci by standard methods of serial dilutions and disc diffusion. Identification of the phenomenon of decreased susceptibility of bacteria to vancomycin by population analysis and concentration gradient. Lipid analysis by thin layer chromatography. Results. High antibacterial activity of vancomycin, daptomycin and linezolid against clinical strains of coagulase-negative staphylococci was shown. The upper limit of the minimum inhibitory concentrations of vancomycin within the sensitive phenotype and the expansion of the ranges of the minimum inhibitory concentrations of daptomycin and warnerin towards an increase in oxacillin-resistant isolates were revealed. The heterogeneous nature of sensitivity to vancomycin of the cultures of the studied strains and the possibility of their rapid enrichment with subpopulations with reduced sensitivity to this antibiotic have been established. The selection of resistance of coagulase-negative staphylococci to vancomycin was accompanied by an increase in the synthesis of lysylphosphatidylglycerol and a decrease in their sensitivity to cationic peptide compounds.Conclusion. The revealed prevalence of the methicillin-resistant phenotype of clinical strains of coagulase-negative staphylococci, along with the presence in the lipid spectrum of the universal factor of resistance to cationic antibacterial compounds, lysylphosphatidylglycerol, entails the need for new methodological solutions for diagnosing infections caused by coagulase-negative staphylococci