Laser Excitation of the Th-229 Nucleus.

The 8.4 eV nuclear isomer state in Th-229 is resonantly excited in Th-doped CaF_{2} crystals using a tabletop tunable laser system. A resonance fluorescence signal is observed in two crystals with different Th-229 dopant concentrations, while it is absent in a control experiment using Th-232. The nuclear resonance for the Th^{4+} ions in Th:CaF_{2} is measured at the wavelength 148.3821(5) nm, frequency 2020.409(7) THz, and the fluorescence lifetime in the crystal is 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum. These results pave the way toward Th-229 nuclear laser spectroscopy and realizing optical nuclear clocks.

Characterisation and feasibility study for superradiant lasing in 40Ca atoms.

Superradiant active clocks operating on narrow linewidth clock transitions are predicted to achieve precision orders of magnitude higher than any currently existing optical atomic clocks. We introduce a theory of superradiant lasing and implement it for the example of 40Ca atoms. The presented model, however, is valid for any two- or three-level system in an optical lattice. We perform a feasibility analysis and suggest a set of parameters for the experimental fulfillment of superradiant lasing in Ca. Moreover, we present an overview of different magic wavelengths for the 4s2 1S0 ↔ 4s4p3P1 (mJ = 0) transition in Ca for different polarizations and a robustness analysis of these magic conditions. We also report the magic-zero wavelengths for the 4s4p3P1, mJ = 0 state.

DFT calculation of 229thorium-doped magnesium fluoride for nuclear laser spectroscopy.

The 229thorium nucleus has an extremely low-energy isomeric state that could be manipulated with light in the vacuum ultraviolet (VUV) range. Recent measurements based on internal conversion electrons place the isomer energy at 8.28(17) eV (Seiferle B et al 2019), within the transmission window of large-band-gap materials, such as fluoride single crystals. Doping 229Th into VUV-transparent materials realizes a spectroscopy target with a high nuclei density and might form the basis of a solid-state nuclear clock. This paper presents a theoretical study of the optical properties of a thorium-doped MgF2 crystal. Using the Vienna Ab-initio Simulation Package, we perform density functional theory calculations of the electronic and optical properties of Th:MgF2. We determine whether thorium will be accepted as a dopant and identify the charge compensation mechanism and geometry. The simulations indicate, that the band gap of Th-doped MgF2 will be significantly reduced compared to undoped MgF2, below the expected 229Th isomer energy. This result is in striking contrast to a similar study performed for Th-doped CaF2 (Dessovic P et al 2014 J. Phys. Condens. Matter 26 105402).

229Thorium-doped calcium fluoride for nuclear laser spectroscopy.

The (229)thorium isotope presents an extremely low-energy isomer state of the nucleus which is expected around 7.8 eV, in the vacuum ultraviolet (VUV) regime. This unique system may bridge between atomic and nuclear physics, enabling coherent manipulation and precision spectroscopy of nuclear quantum states using laser light. It has been proposed to implant (229)thorium into VUV transparent crystal matrices to facilitate laser spectroscopy and possibly realize a solid-state nuclear clock. In this work, we validate the feasibility of this approach by computer modelling of thorium doping into calcium fluoride single crystals. Using atomistic modelling and full electronic structure calculations, we find a persistent large band gap and no additional electronic levels emerging in the middle of the gap due to the presence of the dopant, which should allow direct optical interrogation of the nuclear transition.Based on the electronic structure, we estimate the thorium nuclear quantum levels within the solid-state environment. Precision laser spectroscopy of these levels will allow the study of a broad range of crystal field effects, transferring Mössbauer spectroscopy into the optical regime.

Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter.

The Thorium-229 isotope features a nuclear isomer state with an extremely low energy. The currently most accepted energy value, 7.8±0.5 eV, was obtained from an indirect measurement using a NASA x-ray microcalorimeter with an instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic microcalorimeters with an energy resolution down to a few eV can be used to measure the isomer energy. In particular, resolving the 29.18 keV doublet in the γ-spectrum following the α-decay of Uranium-233, corresponding to the decay into the ground and isomer state, allows to measure the isomer transition energy without additional theoretical input parameters, and increase the energy accuracy. We study the possibility of resolving the 29.18 keV line as a doublet and the dependence of the attainable precision of the energy measurement on the signal and background count rates and the instrumental resolution.

Two-point phase correlations of a one-dimensional bosonic Josephson junction.

We realize a one-dimensional Josephson junction using quantum degenerate Bose gases in a tunable double well potential on an atom chip. Matter wave interferometry gives direct access to the relative phase field, which reflects the interplay of thermally driven fluctuations and phase locking due to tunneling. The thermal equilibrium state is characterized by probing the full statistical distribution function of the two-point phase correlation. Comparison to a stochastic model allows us to measure the coupling strength and temperature and hence a full characterization of the system.

Endogenous marinobufagenin-like immunoreactive substance. A possible endogenous Na, K-ATPase inhibitor with vasoconstrictor activity.

Vasoconstrictor and Na/K pump inhibitory properties of a bufodienolide Na/K-ATPase inhibitor, marinobufagenin, were studied in isolated rings of 2 to 3 order branches of human pulmonary arteries respectively. Marinobufagenin displayed concentration-dependent vasoconstrictor activity (0.01 to 10 mmol/L). In sarcolemma membranes prepared from pulmonary artery marinobufagenin inhibited Na/K-ATPase (IC50 = 50 nmol/L). In eight healthy male Caucasians, concentrations of marinobufagenin-like immunoreactive material in C-18 extracted plasma were 1.38 +/- 0.60 nmol/L. Twenty-four-hour urinary release of marinobufagenin-like immunoreactive material in eight healthy males was 1.20 +/- 0.95 nmol/day. Chloroform extract of human urine was fractionated using reverse-phase high-performance liquid chromatography (32% acetonitrile, Deltapak). The HPLC fraction coeluting with marinobufagenin in 7 min, cross reacted with antimarinobufagenin and antidigoxin, but not antiouabain antibody. These results demonstrate that human plasma and urine contains a bufodienolide vasoconstrictor EDLF, marinobufagenin-like immunoreactive Na,K pump inhibitor.

[The effect of certain factors on binding of tert-butyloxycarbonylamino acids to Merrifield polymer during interphase catalysis and assessment of racemization of the bound amino acid]. / Vliianie nekotorykh faktorov na prisoedinenie tret-butiloksikarbonilaminokislot k polimeru merrifilda v usloviiakh mezhfaznogo kataliza i otsenka ratsemizatsii prisoedinennoi aminokisloty.

In order to reduce the influence of hydrogen bonds on the acylamino acid salts attachment to the chloromethylated resin, it is proposed to use compounds that can compete for the hydrogen bonds formation. The best solvent proved to be hexamethylphosphoric triamide. Use of interphase catalysts, e.g., tributyl-p-nitrobenzyl ammonium, also gives good results. The racemization degree of the amino acids attached to solid support by means of the interphase catalysis does not exceed that of amino acids loaded on the polymer according to Gisin's method.

Upper boundary of the biosphere.

By using meterological rockets fitted with specially designed analyzers, samples for microbiological investigation have been taken. The analyzer design prevented extraneous microorganisms from penetrating into the analyzer. Before being used, the analyzers were sterilized with high gamma-ray doses. For the first time microorganisms have been detected in the mesosphere at an altitude of 48 to 77 km. The microorganisms are microscopic fungi having black conidia or spores (Circinella muscae, Aspergillus niger, Papulaspora anomala) and one species forming green conidia (Penicillium notatum). Colonies of Mycobacterium luteum and Micrococcus albus have also grown. Five of the six species have synthesized pigments. The presence of pigmented microbial forms leads us to believe that natural selection is occurring in the mesosphere because cells possessing chromogenous pigments (carotenoids, melanins) are more resistant to ultraviolet-ray action. A greater number of microorganisms have been registered in the mesosphere during dust storms than in the absence of strong winds.

[Spontaneous crystallization of antibiotic substance during submerged fermentation of Actinomyces hygroscopicus]. / O spontannoi kristallizatsii antibioticheskogo veshchestva pri glubinnoi fermentatsii Actinomyces hydrogscopicus

A rare case of spontaneous crystallization of the antibiotic substance was detected during submerged cultivation of Actinomyces hygroscopicus, strain 33x, under periodic conditions directly in the MTF 5L3 fermenter ("Marubishi"). Leaf-shaped plates of the antibiotic found in the cultural broth of the strain 33x were active against gram-positive and gram-negative microorganisms, yeasts, and fungi. The crystalline state of the structures was confirmed by the X-ray analysis. According to their UV spectrum (maximum at 233-234 nm in ethanol), the crystals belong to the group of nyphimycin A1-scopafungin, antibiotics produced by some cultures of Act. hygroscopicus.

[Method of obtaining enzymatic preparations of lipase from the fungi of the genus Geotrichum under semi-industrial conditions]. / Poluchenie fermentnykh preparatov lipazy iz gribov roda Geotrichum v poluproizvodstvennykh usloviiakh

A method of manufacturing stable enzymic preparations of lipase from fungi Geotrichum candidum and G. asteroides under semi-industrial conditions has been developed. The paper describes the preparation of the inoculate, fermentation nutrient medium, scheme of cultivation and isolation of the raw enzyme with a yield of 31.2%.

On micro-organisms of the stratosphere.

The lower parts of the biosphere are well studied since various live beings are found in oceans and at the bottom of large hollows. Contrary to this, we have no data about the upper boundaries of the biosphere. Samples were obtained with the help of specially constructed analysers which were installed in meteorological rockets and reached an altitude of 100 km. With the help of methods completely excluding the possibility of contamination of analysers with outside microflora it became possible to prove that earth microbes carried by air currents are present in the stratosphere. At an altitude of 48-77 km Circinella muscae, Asp. niger, Penicillium notatum were found as well as mycobacterium and micrococcus. The correlation of these cultures with external factors is studied and the weight of one conidium or one cell in isolated micro-organisms is estimated. These investigations will continue.

[Rapid selection of microorganisms producing extracellular lipases]. / Bystryi otbor mikroorganizmov, obrazuiushchikh vnekletochnye lipazy

A method for rapid selection of microorganisms producing extracellular lipases is described. The method is based on diffusion of the enzyme into agar containing olive oil. The hydrolysis zones revcal by 0,05--0,25% OSO4 solution.