Potential of Geo-neutrino Measurements at JUNO

The flux of geoneutrinos at any point on the Earth is a function of the abundance and distribution of radioactive elements within our planet. This flux has been successfully detected by the 1-kt KamLAND and 0.3-kt Borexino detectors with these measurements being limited by their low statistics. The planned 20-kt JUNO detector will provide an exciting opportunity to obtain a high statistics measurement, which will provide data to address several questions of geological importance. This paper presents the JUNO detector design concept, the expected geo-neutrino signal and corresponding backgrounds. The precision level of geo-neutrino measurements at JUNO is obtained with the standard least-squares method. The potential of the Th/U ratio and mantle measurements is also discussed.Comment: 8 pages, 6 figures, an additional author added, final version to appear in Chin. Phys.

Influence of Fly Ash on Surface Chloride Concentration Under Shallow Immersion Condition

In this paper, the influence of fly ash content on concrete surface chloride concentration was investigated through periodical tests of surface chloride concentration of concrete by immersing three kinds of concrete specimens in 5.0 wt.% sodium chloride solution. One kind of specimen is common concrete without fly ash, whereas the other two kinds of specimens are mixed with fly ash. The results show that the surface chloride ion concentration ranges from 0.295 to 0.777 wt.% for the immersed concrete samples in this study; in the initial stage of immersion, the concrete surface chloride ion concentration is affected by added fly ash, and after 30 days of immersion, the surface chloride concentration of concrete with fly ash is 1.3 times that of concrete without fly ash at the same water–binder ratio; for the concretes without fly ash, the surface chloride concentration is linear with immersion time, whereas for the concrete with fly ash, the surface chloride concentration is nearly linear with square root of immersion time; for the concrete with fly ash, fly ash contents have little impact on the surface chloride concentration, and the surface chloride content of concrete without fly ash is gradually close to that of concrete with 15 and 30 wt.% of fly ash

Optimal Pole Assignment of Linear Systems by the Sylvester Matrix Equations

The problem of state feedback optimal pole assignment is to design a feedback gain such that the closed-loop system has desired eigenvalues and such that certain quadratic performance index is minimized. Optimal pole assignment controller can guarantee both good dynamic response and well robustness properties of the closed-loop system. With the help of a class of linear matrix equations, necessary and sufficient conditions for the existence of a solution to the optimal pole assignment problem are proposed in this paper. By properly choosing the free parameters in the parametric solutions to this class of linear matrix equations, complete solutions to the optimal pole assignment problem can be obtained. A numerical example is used to illustrate the effectiveness of the proposed approach

C-F bond activation under transition-metal-free conditions

The unique properties of fluorine-containing organic compounds make fluorine substitution attractive for the development of pharmaceuticals and various specialty materials, which have inspired the evolution of diverse C-F bond activation techniques. Although many advances have been made in functionalizations of activated C-F bonds utilizing transition metal complexes, there are fewer approaches available for nonactivated C-F bonds due to the difficulty in oxidative addition of transition metals to the inert C-F bonds. In this regard, using Lewis acid to abstract the fluoride and light/radical initiator to generate the radical intermediate have emerged as powerful tools for activating those inert C-F bonds. Meanwhile, these transition-metal-free processes are greener, economical, and for the pharmaceutical industry, without heavy metal residues. This review provides an overview of recent C-F bond activations and functionalizations under transition-metal-free conditions. The key mechanisms involved are demonstrated and discussed in detail. Finally, a brief discussion on the existing limitations of this field and our perspective are presented

catena-Poly[[{2-[(2-hy­droxy­eth­yl)imino­meth­yl]-6-meth­oxy­phenolato}copper(II)]-μ-thio­cyanato]

In the title thio­cyanate-bridged polynuclear copper(II) complex, [Cu(C10H12NO3)(NCS)]n, the Cu atom is five-coordinated in a square-pyramidal geometry, with one phenolato O, one imino N and one hy­droxy O atom of a Schiff base ligand and one thio­cyanato N atom defining the basal plane, and with one thio­cyanato S atom occupying the apical position. In the crystal structure, pairs of adjacent complex mol­ecules are linked through inter­molecular O—H⋯O hydrogen bonds into dimers. The dimers are further linked via Cu⋯S inter­actions, forming two-dimensional layers parallel to the bc plane