Precision determination of absolute neutron flux.

A technique for establishing the total neutron rate of a highly-collimated monochromatic cold neutron beam was demonstrated using an alpha-gamma counter. The method involves only the counting of measured rates and is independent of neutron cross sections, decay chain branching ratios, and neutron beam energy. For the measurement, a target of 10B-enriched boron carbide totally absorbed the neutrons in a monochromatic beam, and the rate of absorbed neutrons was determined by counting 478 keV gamma rays from neutron capture on 10B with calibrated high-purity germanium detectors. A second measurement based on Bragg diffraction from a perfect silicon crystal was performed to determine the mean de Broglie wavelength of the beam to a precision of 0.024%. With these measurements, the detection efficiency of a neutron monitor based on neutron absorption on 6Li was determined to an overall uncertainty of 0.058%. We discuss the principle of the alpha-gamma method and present details of how the measurement was performed including the systematic effects. We also describe how this method may be used for applications in neutron dosimetry and metrology, fundamental neutron physics, and neutron cross section measurements.

Collective Modes and Structural Modulation in Ni-Mn-Ga(Co) Martensite Thin Films Probed by Femtosecond Spectroscopy and Scanning Tunneling Microscopy.

The origin of the martensitic transition in the magnetic shape memory alloy Ni-Mn-Ga has been widely discussed. While several studies suggest it is electronically driven, the adaptive martensite model reproduced the peculiar nonharmonic lattice modulation. We used femtosecond spectroscopy to probe the temperature and doping dependence of collective modes, and scanning tunneling microscopy revealed the corresponding static modulations. We show that the martensitic phase can be described by a complex charge-density wave tuned by magnetic ordering and strong electron-lattice coupling.

High-efficiency cascaded Raman fiber laser with random distributed feedback.

Cascaded lasing provided by Raman gain (at 1115-nm pumping) and random distributed feedback (via Rayleigh backscattering) in a 1.65-km phosphosilicate fiber is studied. Output power for the second Stokes component (1398 nm) exceeds 5 W at pump power of 11 W. In contrast to conventional cascaded Raman laser with high-Q cavity for the intermediate first Stokes component, there is no cavity here and no cavity losses, correspondingly. Longitudinal power distribution is shown to be quite different also. As a result, the efficiency of pump to 2nd Stokes wave conversion is not influenced by the intermediate stage and depends only on the integral attenuation in the fiber. Herewith, the number of generated 2nd Stokes photons at the output may even exceed the absorbed pump photons due to the lower attenuation of Stokes waves.

Retention behavior of carbohydrates on metal loaded chelating stationary phase under conditions of hydrophilic interaction liquid chromatography.

The chromatographic retention of carbohydrates on chelating stationary phase loaded with different metal ions was studied under conditions of hydrophilic interaction chromatography (HILIC). The chelating stationary phases represented silica microparticles with immobilized 2-hydroxyethyliminodiacetic acid (HEIDA) groups in loose form and saturated with Ca2+, Pb2+, and La3+form. The role of loaded metal ion, the acetonitrile and methanol content in the mobile phase, buffer pH and column temperature on the retention of l-(+)-arabinose, d-(+)-maltose, l-(+)-rhamnose, d-(+)-lactose, d-(+)-xylose, glucose, fructose, sucrose, mannose, maltotriose and d-(+) raffinose was studied. The investigation was mainly focused on possible contribution of the complexation in the stationary phase on retention of carbohydrates as well as on effect of the presence metal ion in HEIDA-silica on resulting HILIC behavior of. It is shown that adsorbents with immobilized metal complexes have a good potential for the separation of organic ligands under HILIC mode.

Improved determination of the neutron lifetime.

The most precise determination of the neutron lifetime using the beam method was completed in 2005 and reported a result of τ(n)=(886.3±1.2[stat]±3.2[syst]) s. The dominant uncertainties were attributed to the absolute determination of the fluence of the neutron beam (2.7 s). The fluence was measured with a neutron monitor that counted the neutron-induced charged particles from absorption in a thin, well-characterized 6Li deposit. The detection efficiency of the monitor was calculated from the areal density of the deposit, the detector solid angle, and the evaluated nuclear data file, ENDF/B-VI 6Li(n,t)4He thermal neutron cross section. In the current work, we measure the detection efficiency of the same monitor used in the neutron lifetime measurement with a second, totally absorbing neutron detector. This direct approach does not rely on the 6Li(n,t)4He cross section or any other nuclear data. The detection efficiency is consistent with the value used in 2005 but is measured with a precision of 0.057%, which represents a fivefold improvement in the uncertainty. We verify the temporal stability of the neutron monitor through ancillary measurements, allowing us to apply the measured neutron monitor efficiency to the lifetime result from the 2005 experiment. The updated lifetime is τ(n)=(887.7±1.2[stat]±1.9[syst]) s.

[Synthesis of spyropyran derivatives of retinal and study of their interaction with bacterioopsin from Halobacterium salinarum].

The synthesis of retinal analogue series that contain a spyropyran moiety instead of a trimethylcyclohexene ring was proposed. The process of the retinal analogue interaction with bacterioopsin from apomembranes of Halobacterium salinarum and the spectral properties of the newly formed pigments were studied. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru.

The aCORN Backscatter-Suppressed Beta Spectrometer.

Backscatter of electrons from a beta spectrometer, with incomplete energy deposition, can lead to undesirable effects in many types of experiments. We present and discuss the design and operation of a backscatter-suppressed beta spectrometer that was developed as part of a program to measure the electronantineutrino correlation coefficient in neutron beta decay (aCORN). An array of backscatter veto detectors surrounds a plastic scintillator beta energy detector. The spectrometer contains an axial magnetic field gradient, so electrons are efficiently admitted but have a low probability for escaping back through the entrance after backscattering. The design, construction, calibration, and performance of the spectrometer are discussed.

aCORN: An experiment to measure the electron-antineutrino correlation coefficient in free neutron decay.

We describe an apparatus used to measure the electron-antineutrino angular correlation coefficient in free neutron decay. The apparatus employs a novel measurement technique in which the angular correlation is converted into a proton time-of-flight asymmetry that is counted directly, avoiding the need for proton spectroscopy. Details of the method, apparatus, detectors, data acquisition, and data reduction scheme are presented, along with a discussion of the important systematic effects.

[Search for new products of gene expression in human cardiac muscle. Microsequencing of proteins after two-dimensional electrophoresis]. / Poisk novykh produktov gennoi ékspressii v serdechnoi myshtse cheloveka. Mikrosekvenirovanie belkov posle dvumernogo élektroforeza.

Proteins of the human heart muscle were studied using modified two-dimensional electrophoresis. After separation, proteins were electroblotted onto Immobilon P membranes and several protein spots were used for microsequencing analysis. In most cases the proteins analyzed have blocked N-terminal amino acids. In order to study the primary structure of these proteins, hydrolysis in situ by trypsin followed by reversed-phase HPLC and microsequencing of the resulting peptides were performed. Four protein were identified in 8 analyzed fractions, specifically myosin light chain 1 (MLCl-V/sB), fatty-acid binding protein (heart isoform), alpha (B)-crystallin and alpha-tropomyosin. Amino acid sequences of two proteins were not found among human amino acid sequences collected in SWISSPROT bank (v. 21).

[The dynamics of the properties of liver phenylalanine hydroxylase in human embryogenesis]. / Dinamika svoistv fenilalaningidroksilazy pecheni v émbriogeneze cheloveka.

Content, subunit composition and activity of phenylalanine hydroxylase's (PH) (EC 1.14.16.1) in cytoplasmic and membrane proteins extract of embryonic liver on week 6-11 of pregnancy were studied. PH enzymatic and antigenic activities were detected starting from the week 6 of pregnancy. Liver cytoplasmic PH antigen content increased gradually during development while its enzymatic activity remained practically unchanged. Concomitantly, relative content of L-subunit increased. Content of liver membrane PH antigen was constant during development. Samples of liver with relatively low specific PH activity were characterized by high content of PH in cytoplasm and vice versa. Since PH activity in extracts prepared from mixture of these samples decreased, an unknown PH inhibitor must be present in cytoplasmic protein extracts with relatively low specific PH activity.

[Phenylalanine hydroxylase of human embryos: its homology with the enzyme from the liver of adults]. / Fenilalaningidroksilaza émbrionov cheloveka: gomologiia s fermentom iz pecheni vzroslykh liudei.

Phenylalanine hydroxylase (PH) activity was discovered in the liver of 7-12 week old human embryos. Embryonic and adult PHs were identical, as shown by immunoelectrophoresis. Unlike the adult liver PH, the PH content of the extract of cytoplasmic proteins of embryonic liver was reduced but the specific activity was increased more than by one order of magnitude. H (57,000 D) and L (55,000 D) subunits were detected by immunoblotting. The L subunit predominates in the extract of membrane proteins of embryonic liver. Hence, the major part of phenylalanine oxidizing activity in the embryonic liver is related to the enzyme immunochemically identical with the PH of adult liver but differing from it in some structural and functional properties.

[Clinico-rheoencephalographic characteristics and criteria for different initial forms of atherosclerotic brain lesions]. / Kliniko-reoéntsefalograficheskaia kharakteristika i kriterii razlichiia nachal'nykh form ateroskleroticheskikh porazhenii mozga.

The author analyzes the clinical and rheoencephalographic characteristics of the cerebral circulation in 252 patients with initial signs of cerebral circulation insufficiency, 198 patients with the initial stage of dyscirculatory encephalopathy due to atherosclerosis, and in 149 healthy subjects of a young age. Distinct criteria for differentiating the above groups have been defined. These criteria are necessary for developing an automated system of prophylactic examinations of population.

[Immunochemical detection of phenylalanine hydroxylase in extracts of various human organs]. / Immunokhimicheskoe vyiavlenie fenilalaningidroksilazy v ékstraktakh nekotorykh organov cheloveka.

Phenylalanine hydroxylase was found in extracts from autoptates of human liver, kidney, myocardium, small intestine, lung and spleen. In all the tissues studied, except of spleen, the antigen was detected by immunoelectrophoresis with monospecific antiserum against human liver phenylalanine hydroxylase. As shown by immunoblotting carried out after electrophoresis under denaturating conditions, the antigen, observed in various tissues, exhibited similar electrophoretic mobility which was very close to that of the enzyme purified from human liver tissue. Molecular mass of revealed antigen was estimated 55-57 kDa. Coincidence of immunochemical and chemical properties of the protein suggested that the antigen, detected in the tissue extracts, was a product of phenylalanine hydroxylase gene expression. The antigen concentration did not correlate with the content of albumin in tissue extracts, thus demonstrating that the revealed antigen did not occur in these preparations with blood contaminations. Content of the antigen in the tissue extracts studied was (ug per g): liver - 1500-1900, kidney - 300-575, brain - 20-40, myocardium - 85-105, lung - 40-125, small intestine - 45-70, spleen - 0-12.

[Simulator of cardiac activity signals]. / Imitator signalov serdechnoi deiatel'nosti.

Imitators of physiological signals are in need for production of electronic medical equipment and modeling the biological systems. The known imitators are rather intricate and incapable to control the output signal within a wide range. The imitator now offered allows to reproduce any signal that reflects the activity of a cardiovascular system under normal and pathologic conditions.

[Operational control of the effectiveness of assisted blood circulation]. / Operativnyi kontrol' éffektivnosti vspomogatel'nogo krovoobrashcheniia.

Introduction into the clinical practice of methods providing for mechanic support to the heart demands equipping the apparatus of assisted circulation with appliances, helping to operatively assess the effect of applying some or other procedures helping the heart performance. The existing criteria do not allow the degree of restoring the contractility of the myocardium under the effect of assisted circulation to be appraised. Criteria may be of help in comparing the energy balance of the myocardium with application of assisted circulation and the energy balance of an unloaded myocardium are proposed.