Spin of Protons in NICA and PTR Storage Rings as an Axion Antenna

JETP Letters - A new approach to search for axions in the storage ring experiments, applicable at a short coherence time of the in-plane polarization as is the case for protons is discussed. The...     

Study of Features of DDL Schemes Applied in the Method of Discrete Ordinates to Calculate Two-Dimensional Grid Problems with Arbitrary Quadrilaterals

Physics of Atomic Nuclei - The results on estimating error is presented in applying two-dimensional DDL schemes in the method of discrete ordinates to calculate arbitrary quadrilateral cells.     

New Method for Measuring the Refractive Index of Flowing Liquid

Optics and Spectroscopy - The necessity of a new method for measuring the refractive index of a turbulently flowing fluid in a pipeline is substantiated. A new method for measuring refractive index...     

A Silver-Based Electrocontact Material Dispersion-Strengthened with Zinc,Tin, and Titanium Oxides

Technical Physics - A new silver-based electrocontact material dispersion-strengthened with nanopowders of zinc, tin, and titanium oxides has been obtained. The microstructure and elemental...     

Investigations and Modeling of the Effect of Magnetic Nanoparticles on MR Image Contrast

The investigations of nuclear magnetic resonance (NMR) relaxation of protons in aqueous solution and 2% agar–agar gel in the presence of magnetic nanoparticles were performed. To identify the effect of magnetic nanoparticles on the contrast of magnetic resonance images, the dependences of the MR signal intensity on the parameters of the two pulse radio-frequency (RF) sequences (spin-echo, gradient-echo) most commonly used in MRI for different values of the magnetic nanoparticle (MNP) concentration were simulated and analyzed. Recommendations for choosing the optimal values of pulse RF sequence parameters for MR imaging (MRI) in the presence of MNPs are formulated. MRI studies of phantom samples with 2% agar–agar gel containing MNPs have been performed for choosing the fast pulse RF sequence which shows the greatest contrast effect on MR images. A program for modeling magnetic resonance tomograms and determination of optimal values of pulse RF sequence parameters to achieve the best contrast of magnetic resonance images is developed. This program allows to reduce the time of MRI studies, to assess the possibility of using MNPs for contrast of MR images and to simulate the MR image in the presence of magnetic nanoparticles at the planning stage of procedures in MR-guided theranostics.     

Two-Photon Excitation Fluorescence Microscopy of Rat Elastin Fiber In Vivo

Russian Physics Journal - The paper presents the results of two-photon excitation fluorescence microscopy of rat elastin fiber in vivo. It is shown that in approximating the fluorescence...     

Specific properties of hydroxyapatite as a potential transporter of copper ions and its complexes

Russian Chemical Bulletin - Modification of the cocrystallization method for producing hydroxyapatite (HAP) and an HAP-Cu combination to the enzymatic method using alkaline phosphatase leads to a...     

Dynamic Modeling of the Feed Drive System of a CNC Metal Cutting Machine

Studying the vibrational behavior of feed drive systems is important for enhancing the structural performance of computer numerical control (CNC) machines. The preload on the screw and nut position have a great influence on the vibration characteristics of the feed drive as two very important operational conditions. Rotational acceleration of the screw also affects the performance of the CNC feed drive when machining small parts. This paper investigates the influence of preload and nut position on the vibration characteristics of the feed drive system of a CNC metal cutting machine in order to be able to eliminate an observed resonance occurred at high rotational speeds of the screw, corresponding to high feed rates. Additionally, rational structural parameters of the feed drive system are selected in order to increase the rotational acceleration for improving the performance of the CNC machine. Experiments and analyses showed that by selecting specific parameters of feed drive system and simultaneously applying a certain value of preload, a 97% increase in rotational acceleration and 30% time reduction considering the vibration resistance at high rotational speeds can be achieved.