Spin squeezing and quantum correlations

We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.     

Differential effects of plasma membrane electric excitation on H+ fluxes and photosynthesis in characean cells

Cells of characean algae exposed to illumination arrange plasma-membrane H(+) fluxes and photosynthesis in coordinated spatial patterns (bands). This study reveals that H(+) transport and photosynthesis patterns in these excitable cells are affected not only by light conditions but also by electric excitation of the plasma membrane. It is shown that generation of action potential (AP) temporally eliminates alkaline bands, suppresses O(2) evolution, and differentially affects primary reactions of photosystem II (PSII) in different cell regions. The quantum yield of PSII electron transport decreased after AP in the alkaline but not in acidic cell regions. The effects of electric excitation on fluorescence and the PSII electron flow were most pronounced at light-limiting conditions. Evidence was obtained that the shift in chlorophyll fluorescence after AP is due to the increase in DeltapH at thylakoid membranes. It is concluded that the AP-triggered pathways affecting ion transport and photosynthetic energy conversion are linked but not identical.     

Phase composition,physicochemical and catalytic properties of cobalt–aluminum–zeolite systems

The phase composition and physicochemical and catalytic properties of three samples of cobalt–aluminum–zeolite systems were studied. The catalytic properties of the systems are related to the application of a highly porous acidic support and the presence of cobalt oxide crystallites of an optimal size (6–12 nm). The occurrence of an efficient heat-conductive spatial net formed by metallic aluminum particles is also important for catalytic performance.     

Oligomerization of higher olefins and alkylation of toluene catalyzed by 2-[hydroxy(diaryl)methyl]-8-hydroxyquinoline oxovanadium(v) complexes

Russian Chemical Bulletin - New oxovanadium(V) complexes with 2-[hydroxy(diaryl)methyl]-8-hydroxyquinoline ligands were synthesized. These compounds were found to be efficient tandem catalysts of...     

Double-bridge bonding of aluminium and hydrogen in the crystal structure of gamma-AlH3

Aluminum trihydride (alane) is one of the most promising among the prospective solid hydrogen-storage materials, with a high gravimetric and volumetric density of hydrogen. In the present work, the alane, crystallizing in the gamma-AlH3 polymorphic modification, was synthesized and then structurally characterized by means of synchrotron X-ray powder diffraction. This study revealed that gamma-AlH3 crystallizes with an orthorhombic unit cell (space group Pnnm, a = 5.3806(1) A, b = 7.3555(2) A, c = 5.77509(5) A). The crystal structure of gamma-AlH3 contains two types of AlH6 octahedra as the building blocks. The Al-H bond distances in the structure vary in the range of 1.66-1.79 A. A prominent feature of the crystal structure is the formation of the bifurcated double-bridge bonds, Al-2H-Al, in addition to the normal bridge bonds, Al-H-Al. This former feature has not been previously reported for Al-containing hydrides so far. The geometry of the double-bridge bond shows formation of short Al-Al (2.606 A) and Al-H (1.68-1.70 A) bonds compared to the Al-Al distances in Al metal (2.86 A) and Al-H distances for Al atoms involved in the formation of normal bridge bonds (1.769-1.784 A). The crystal structure of gamma-AlH3 contains large cavities between the AlH6 octahedra. As a consequence, the density is 11% less than for alpha-AlH3.     

Neutral Pion Photoproduction on Neutron

The reaction γn → π⁰n is investigated both theoretically and experimentally as an important step toward determining the electromagnetic coupling constants of the N* and Δ* resonances [1]. We analyze the data on the collisions of γ quanta with energies between 200 and 800 MeV with a deuterium target collected by the A2 experiment in Mainz, Germany. These complement the data for neutral-pion photoproduction on protons obtained by the same experiment [2].     

Plasma Discharge in Liquid Phase Media under Ultrasonic Cavitation as a Technique for Synthesizing Gaseous Hydrogen

It is shown that low-temperature plasma initiated in liquid-phase media in the discharge gap between electrodes can efficiently decompose hydrogen-containing molecules of organic compounds with the formation of gaseous products in which the hydrogen fraction is more than 90% (according to gas chromatography data). Preliminary estimations of the energy efficiency calculated taking into account the hydrogen and source material combustion heat and electric power expenditures showed the efficiency of the order of 60–70% depending on the source mixture composition. The discharge voltage and current were theoretically calculated in the process simulation whose data are in agreement with experimental results.     

Isotope Effects in the Spectra of Hydrogen-Bonded Complexes. Experimental and Theoretical Study of an IR Absorption Spectrum of the (12CH3) $$_{2}^{{13}}$$ CO…HF Complex

Optics and Spectroscopy - IR absorption spectra of mixtures (12CH3) $$_{2}^{{13}}$$ CO/HF and free (12CH3) $$_{2}^{{13}}$$ CO molecules are recorded in the region of 4000−800 cm−1 with...