Comparison of two experiments on radiative neutron decay

Over 10 years ago we proposed an experiment on measuring the characteristics of radiative neutron decay in papers [1, 2]. At the same time we had published the theoretical spectrum of radiative gamma quanta, calculated within the framework of the electroweak interactions, on the basis of which we proposed the methodology for the future experiment [3,4]. However, because we were denied beam time on the intensive cold neutron beam at ILL (Grenoble, France) for a number of years, we could only conduct the experiment in 2005 on the newly opened FRMII reactor of Technical University of Muenchen. The main result of this experiment was the discovery of radiative neutron decay and the measurement of its relative intensity B.R.= (3.2+-1.6)10-3 with C.L.=99.7% for radiative gamma quanta with energy over 35 kev [5,6]. Over a year after our first announcement about the results of the conducted experiment, "Nature" [7] published a letter asserting that its authors have also measured the branching ratio of radiative neutron decay B.R.= (3.13+-0.34)10-3 with C.L.=68% and gamma quanta energy from 15 to 340 kev. This article aims to compare these two experiments. It is shown that the use of strong magnetic fields in the NIST (Washington, USA) experiment methodology not only prevents any exact measurement of the branching ratio and identification of radiative neutron decay events, but also makes registration of ordinary neutron decay events impossible.Comment: contribution on conference ISINN-1

Alignment of helical membrane protein sequences using AlignMe

Few sequence alignment methods have been designed specifically for integral membrane proteins, even though these important proteins have distinct evolutionary and structural properties that might affect their alignments. Existing approaches typically consider membrane-related information either by using membrane-specific substitution matrices or by assigning distinct penalties for gap creation in transmembrane and non-transmembrane regions. Here, we ask whether favoring matching of predicted transmembrane segments within a standard dynamic programming algorithm can improve the accuracy of pairwise membrane protein sequence alignments. We tested various strategies using a specifically designed program called AlignMe. An updated set of homologous membrane protein structures, called HOMEP2, was used as a reference for optimizing the gap penalties. The best of the membrane-protein optimized approaches were then tested on an independent reference set of membrane protein sequence alignments from the BAliBASE collection. When secondary structure (S) matching was combined with evolutionary information (using a position-specific substitution matrix (P)), in an approach we called AlignMePS, the resultant pairwise alignments were typically among the most accurate over a broad range of sequence similarities when compared to available methods. Matching transmembrane predictions (T), in addition to evolutionary information, and secondary-structure predictions, in an approach called AlignMePST, generally reduces the accuracy of the alignments of closely-related proteins in the BAliBASE set relative to AlignMePS, but may be useful in cases of extremely distantly related proteins for which sequence information is less informative. The open source AlignMe code is available at https://sourceforge.net/projects/alignme​/, and at http://www.forrestlab.org, along with an online server and the HOMEP2 data set

Determination of regression materials mircohardness, processed by low-temperature plasma dependence on process conditions

© Published under licence by IOP Publishing Ltd.The influence of conditions of plasma surface treatment on hardening of carbon steel technological process was analyzed. Hardening was carried out in plasma electrothermal line with an electrolytic cathode. When processing, steel crystal grains are crushed and the structure is changed from ferrite-pearlite to bainite-troostite and martensite, depending on the processing conditions. In this case the surface microhardness increase in 2 - 3 times. The dependence of the carbon steel surface microhardness on the discharge current (2 - 10 A), the distance between the heat source and the surface, the plasma gas flow rate and treatment duration was found. On the basis of multifactor experiment planning methods and the method of least squares, the formula that describes this relationship was found. This allowed to conduct a targeted search of optimal conditions of processes of hardening steel and improve the efficiency and quality of research

Plasma spray coating with ferromagnetic powder by thermo-electric plasma equipment

© Published under licence by IOP Publishing Ltd. Plasma spray coating is the most preferred and readily available method of carrying out repair and restoration works in comparison to other methods at present. Though the method of plasma spraying has been known for a long time, there are still a number of unsolved issues related to the choice of optimal deposition regimes. The thermo-electric plasma system for plasma spray coating with a liquid electrode is discussed in this article. The process and optimal parameters of plasma spray coating regimes are described

Erosion of electrode metal in the electric discharge under the exposure of the electrolyte stream

The discharge between solid and liquid electrodes under the normal atmospheric conditions (SATP) was investigated. As electrodes, the metal materials and unsaturated salts solutions are used. Such discharge takes place in the range of voltage from 510 V to 525 V, a current from 0.2 A to 6 A, a electrolyte liquid flow rate from 2 cm3/s to 14 cm3/s, an electrolyte stream length from 5 mm to 40 mm. Increasing the flow rate of electrolyte liquid increases the discharge current. There are minimum and maximum critical values of the electrolyte flow rate of beyond which the existence of discharge is impossible. Specific values of the critical flow rate of the electrolyte depend on the nature, composition and stream length of the electrolyte. The electrical discharge between the electrolyte stream and a metal electrode is followed by erosion of the electrode material. The technique for local removal of metal by means of such a discharge is developed and the optimal values of erosion treatment parameters are determined. By using the discharge, technical processes of cleaning surface, deburring, drilling and cutting of metal materials were implemented

Computational and Experimental Studies of Substrate Binding, Conformational Change and Importance of the Trimeric State in the Glycine Betaine Transporter BetP

The glycine betaine/sodium symporter BetP responds to changes in external osmolality by regulation of its transport activity. A recent X-ray structure of BetP confirms that it is a homotrimer and in this structure each protomer adopts an identical conformation, in which the pathway is occluded from both sides. Despite the availability of a wealth of experimental data for BetP, the structures of the alternate states (e.g., open to the outside of the cell), molecular mechanisms of substrate and Na⁺ binding and transport, as well as the functional implications of the trimeric state remain poorly understood. To address these questions, we carried out computational studies using a range of techniques to derive hypotheses that were then tested experimentally. First, to identify structural features of the alternate states, we developed a procedure for flexible fitting of the X-ray structure of BetP into a lower-resolution cryo-EM map of BetP in a more native lipid environment, in which the three protomers have different conformations. These results suggest that: (i) the protomers adopt distinct conformational states relevant to the transport cycle; and (ii) there is conformational coupling between the protomers. Second, we performed all-atom molecular dynamics simulations and in silico alanine scanning of BetP trimers in order to identify interface residues crucial for maintaining the trimeric state. Mutations of these residues to alanine were introduced experimentally revealing that the isolated monomers are functional, and that the trimeric state is important for the regulation and higher activity of the protein. Finally, using molecular modeling and biochemical experiments we identified two Na⁺ binding sites in BetP that could not be resolved in the 3.35 Å resolution X-ray structure