Agricultural development and the opportunities for aquatic resources research in China

China is a large and rapidly developing country. Fisheries and aquaculture have been prominent sectors in the contribution to GDP and the provision of food security, export revenue, and livelihoods for the poor. The rapid development has come at some cost to the environment and the sustainability of natural resources. Levels of marine fisheries catches are stagnant. Some of the rivers and major lakes are polluted and the restoration of the productivity of these lakes is of key concern. These Proceedings, made up of four papers that leading Chinese experts presented to WorldFish Center in 2002, review four aspects of these trends: agricultural development, environmental issues and the contribution of aquaculture and fisheries to development in China.Agricultural development, Aquaculture development, Living resources, Research, WorldFish Center, WorldFish Center Contrib. No. 1668, China,

Structure–property relationships of low sintering temperature scheelite-structured (1 − x)BiVO 4 –xLaNbO 4 microwave dielectric ceramics

A series of (1 − x)BiVO4–xLaNbO4 (0.0 ≤ x ≤ 1.0) ceramics were prepared via a solid state reaction method. A scheelite-structured solid solution was formed for x ≤ 0.5 but for x > 0.5, tetragonal scheelite, monoclinic LaNbO4-type and La1/3NbO3 phases co-existed. As x increased from 0 to 0.1, the room temperature crystal structure gradually changed from monoclinic to tetragonal scheelite, associated with a decrease in the ferroelastic phase transition temperature from 255 °C (BiVO4) to room temperature or even below. High sintering temperatures were also found to accelerate this phase transition for compositions with x ≤ 0.08. Temperature independent high quality factor Qf >10 000 GHz in a wide temperature range 25–140 °C and high microwave permittivity εr ∼76.3 ± 0.5 was obtained for the x = 0.06 ceramic sintered at 800 °C. However, small changes in composition resulted in a change in the sign and magnitude of the temperature coefficient of resonant frequency (TCF) due to the proximity of the ferroelastic transition to room temperature. If TCF can be controlled and tuned through zero, then (1 − x)BiVO4–xLaNbO4 (0.0 ≤ x ≤ 1.0) is a strong candidate for microwave device applications

Temperature stable K0.5(Nd1−xBix)0.5MoO4 microwave dielectrics ceramics with ultra-low sintering temperature

K 0.5 (Nd 1-x Bi x ) 0.5 MoO 4 (0.2 ≤ x ≤ 0.7) ceramics were prepared via the solid-state reaction method. All ceramics densified below 720°C with a uniform microstructure. As x increased from 0.2 to 0.7, relative permittivity (e(open) r ) increased from 13.6 to 26.2 commensurate with an increase in temperature coefficient of resonant frequency (TCF) from - 31 ppm/°C to + 60 ppm/°C and a decrease in Qf value (Q = quality factor; f = resonant frequency) from 23 400 to 8620 GHz. Optimum TCF was obtained for x = 0.3 (-15 ppm/°C) and 0.4 (+4 ppm/°C) sintered at 660 and 620°C with e(open) r ~15.4, Q f ~19 650 GHz, and e(open) r ~17.3, Q f ~13 050 GHz, respectively. Ceramics in this novel solid solution are a candidate for ultra low temperature co-fired ceramic (ULTCC) technology

Quantum computation with two-level trapped cold ions beyond Lamb-Dicke limit

We propose a simple scheme for implementing quantum logic gates with a string of two-level trapped cold ions outside the Lamb-Dicke limit. Two internal states of each ion are used as one computational qubit (CQ) and the collective vibration of ions acts as the information bus, i.e., bus qubit (BQ). Using the quantum dynamics for the laser-ion interaction as described by a generalized Jaynes-Cummings model, we show that quantum entanglement between any one CQ and the BQ can be coherently manipulated by applying classical laser beams. As a result, universal quantum gates, i.e. the one-qubit rotation and two-qubit controlled gates, can be implemented exactly. The required experimental parameters for the implementation, including the Lamb-Dicke (LD) parameter and the durations of the applied laser pulses, are derived. Neither the LD approximation for the laser-ion interaction nor the auxiliary atomic level is needed in the present scheme.Comment: 12 pages, no figures, to appear in Phys. Rev.

The superconductivity at 18 K in LiFeAs system

A new iron arsenide superconducting system LiFeAs was found that crystallizes into a tetragonal structure with space group P4/nmm. The superconductivity with Tc up to 18 K was observed in the compounds. This simple 111 type layered iron arsenide superconductor can be viewed as an analogue of the infinite layer structure of copper oxides.Comment: 11 pages 3 Figure

Progress on the Design of the Coupling coils for MICE andMUCOOL

The Muon Ionization Cooling Experiment (MICE) [1]willdemonstrate ionization cooling in a short section of a realistic coolingchannel using a muon beam at Rutherford Appleton Laboratory (RAL) in theUK. The MICE RF and Coupling Coil (RFCC) Module consists of asuperconducting solenoid mounted around four normal conducting 201.25-MHzRF cavities. The coil package that surrounds the RF cavities is to bemounted in a 1.4 m diameter vacuum vessel. The coupling coil confines thebeam in the RFCC module within the radius of the RF cavity beam windows.Each coupling magnet will be powered by a 300 A, 10 V power supply. Themaximum design longitudinal force that will be carried by the cold masssupport system is 0.5 MN. The detailed design and analysis of thecoupling magnet has been completed by ICST. The primary magnetic andmechanical design features of the coils are presented in thispaper

Doping-insensitive density-of-states suppression in polycrystalline iron-based superconductor SmO1−x_{1-x}Fx_{x}FeAs

We investigated the temperature dependence of the density-of-states in the iron-based superconductor SmO_1-xF_xFeAs (x=0, 0.12, 0.15, 0.2) with high resolution angle-integrated photoemission spectroscopy. The density-of-states suppression is observed with decreasing temperature in all samples, revealing two characteristic energy scales (10meV and 80meV). However, no obvious doping dependence is observed. We argue that the 10meV suppression is due to an anomalously doping-independent normal state pseudogap, which becomes the superconducting gap once in the superconducting state; and alert the possibility that the 80meV-scale suppression might be an artifact of the polycrystalline samples.Comment: 4 pages, 4 figure