Cre-lox66/lox71-Based Elimination of Phosphotransacetylase or Acetaldehyde Dehydrogenase Shifted Carbon Flux in Acetogen Rendering Selective Overproduction of Ethanol or Acetate

Acetogen strain Clostridium sp. MT1121 produced 300?mM acetate (p?<?0.005) and 321?mM ethanol (p?<?0.005) from synthesis gas (syngas) blend 60?% CO and 40?%?H₂. Clostridium sp. MT1121 was metabolically engineered to eliminate production of either acetate or acetaldehyde during syngas fermentation. We used Cre-lox66/lox71-based gene removal system to eliminate either phosphotransacetylase (pta), or acetaldehyde dehydrogenase (aldh). The resulted biocatalyst with eliminated pta increased ethanol yield to 610?mM (p?<?0.005). Inactivation of pta rendered only 502?mM of ethanol (p?<?0.005). The acetogen biocatalyst with eliminated aldh produced 450?mM acetate (p?<?0.005). The role of cell energy pool preservation for re-directed carbon flux is discussed. This is the first report on time- and cost-efficient gene elimination in acetogens using lox66/lox71 gene elimination system.     

A three body approach to study the structural properties of 2-n halo nuclei and the search for Efimov states

The discovery of neutron rich isotopes of the lightest elements on the neutron drip line exhibiting a halo structure has opened up new vistas in research activities. The novel structural features associated with the halo phenomena have been the subject for extensive theoretical and experimental investigations in recent times. In this talk, I propose to present a broad overview of the recent developments in this field, bringing out the striking features which show that a large number oflight nuclei near the neutron drip line are characterized by a clear separation between a ‘normal’ core nucleus and a loosely bound low density veil of neutrons. Specifically, the two neutron halos offer a natural premises, from a theoretical standpoint, to employ three body techniques for studying their detailed structural properties. A considerable part of the talk will be devoted to report and highlight the results on a number of light halo nuclei such as ¹¹Li, ¹¹Be, ¹⁹B and ²²C on which we have been carrying out investigations employing a simple but realistic three body model. These three body systems which have been termed as ‘Borromean’ (i.e while three body systems are bound, the corresponding binary subsystems on the other hand are unbound) are characterized by large spacial extension and very low separation energy of the neutron. They are, therefore, ideally suited for exploring the possibility of the existence of Efimov states in two neutron halo nuclei. We have recently carried out the three body analyses to predict the possibility of the occurrence of such states on which experimental work at various laboratories is underway.     

A closeness estimate for probability distribution and its zero bias transformation

A new concise and transparent proof for the optimal estimate concerning the mean metric distance between a probability distribution and its zero bias transformation is given.     

α + 12C scattering at 110 MeV: Has exotic 7.65 MeV Hoyle’s state signatures “alpha-condensate” structure?

We present new measurements of the α + ¹²C elastic and inelastic (to the states 4.44, 7.65, and 9.64 MeV) scattering at E _lab = 110 MeV in the wide angular range from ～10° to 175°, which enable us to examine the condensate and cluster properties of the low-lying excited states in ¹²C. We present the diffraction-radius analysis of our data together with a considerable amount of the existing data. The magnitudes of the diffraction radii for the ground and the first excited (4.44 MeV) states are found to be equal, whereas they appear to be enhanced by ～0.6 fm both for 7.65 and 9.64 MeV states. This result shows that the radius of the Hoyle’s 0 ₂ ⁺ , 7.65 MeV state in ¹²C is by a factor of ～1.2–1.3 larger than that of the ground state. It is demonstrated that the direct transfer mechanism of ⁸Be dominates at the largest angles in all four reactions reported here. The configuration corresponding to the transfer of ⁸Be in its ground state (I ^π = 0⁺) with L = 0 turns out to be the most important for the 7.65 MeV state of ¹²C. Evidence of existence of some features of α-condensed structure of the Hoyle’s 0 ₂ ⁺ state in ¹²C was obtained: its enhanced radius and large contribution of α-particle configuration with L = 0.     

Abelian monopoles and complex geometry

Three remarks concerning the constructive properties of smooth 4-manifolds with nontrivial Seiberg-Witten invariants are presented. Translated fromMatematicheskie Zametki, Vol. 65, No. 3, pp. 420–428, March, 1999.     

Excitation of the hydrogen subsystem in metals and alloys by ionizing radiation

Models of nonequilibrium-stimulated diffusion and the release of hydrogen and its isotopes from metals by the action of ionizing radiation are considered. It is suggested that the acceleration of the release of hydrogen from metals by the action of radiation is due to the excitation of nonequilibrium vibrational states in the hydrogen subsystem of the metals and a reduction in the surface potential barrier by the desorbing molecules. It is shown, in particular, that the diffusion coefficient of deuterium in Pd is increased by a factor of 30 by the action of radiation compared with a nonirradiated sample. Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 3–10, November, 1998.     

Effect of Organotin Compounds and Their Complexes with Phosphatidylcholine on Peroxide Oxidation of Lipid Structural Fragments

Oxidation of a lipid structural fragment, oleic acid, in the presence of a series of organotin compounds and their complexes with phosphatidylcholine was studied at 25, 37, 65, and 95°C. At a nearly physiological temperature, acceleration of hydroperoxide accumulation in the presence of these complexes was observed. At 65°C, addition of organotin derivatives leads to increase in the initial rate of hydroperoxide accumulation, but the kinetic curves acquire an S-like character as the reaction progresses. These data indicate that the rate of decomposition of hydroperoxides exceeds the rate of their accumulation. In the presence of 2,6-di-tert-butylphenol as antioxidant, the promoting effect of organotin compounds disappears. A possible reaction mechanism and the role of radical species arising from dissociation of the CÄSn bond are discussed.     

A physical model of the action of low-intensity laser radiation on biological objects

A new model of the action of low-intensity laser radiation (LILR) on biological objects on the cellular level is proposed. The model implies that, because the laser radiation is coherent, the illumination in the bulk of a biological object can acquire a spatially periodic character (in the form of an interference pattern or speckle structure), with the period of alternating dark and light regions being comparable with the size of cells or cell organelles. Under these conditions of high-gradient illumination, an electrical field can arise (the Dember effect) that can change the character of photostimulated reactions and the membrane charge state not only in the cell itself but also in its organelles, which leads to shifts in the life cycle of cells (and/or bacteria).     

Excitation of the hydrogen subsystem in metals and alloys by ionizing radiation

The results of research on the nonequilibrium liberation of deuterium from niobium, palladium, and stainless steel under electron-beam bombardment are reported. The maximum on the deuterium gas liberation curve in the low-temperature region is shown to shift under linear heating with simultaneous electron-beam bombardment in comparison with linear heating without such bombardment. The shift reaches 130° in Nb, 100° in stainless steel, and 65° in Pd. The rate of radiation-stimulated gas liberation increases nonlinearly with the concentration of deuterium introduced and the electron-beam current. Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, p. 41–46. July, 1998.