Spatial-temporal characteristics and driving factors of the chemical fertilizer supply/demand correlation network in China.

The rational allocation of chemical fertilizer resources is of strategic importance in mitigating agricultural source pollution and achieving agricultural green development. The spatiotemporal correlation of chemical fertilizer supply/demand and its determinants remains unclear. In this study, based on the inter-provincial chemical fertilizer supply/demand panel data of China from 1994 to 2018, an improved gravity model was employed to determine provincial chemical fertilizer supply/demand correlations.

Calibration methods and facilities for vector receivers using a laser Doppler vibrometer in the frequency range 20 Hz to 10 kHz.

Calibration methods and facilities have been employed to directly obtain sensitivities of an underwater acoustic vector receiver using two methods based on laser Doppler vibrometry. The vector receiver was first calibrated in a standing wave tube over the frequency range 20 Hz to 2 kHz, where the oscillatory velocity of the water-air interface was measured to determine the sound particle velocity at the position of vector receiver based on waveguide theory. In the frequency range 2.

A precise hexagonal octadecanuclear Ag macrocycle with significant luminescent properties.

The first hexagonal octadecanuclear Ag macrocycle [Ag(18)(TTTMB)(12)](NO(3))(18)·30H(2)O has been hydrothermally synthesized. The outside and inner diameters of the unprecedented architecture are about 27.72(13) Å and 15.