N‐(4‐Bi­phenyl­yl)­urea

In the crystal structure of the title compound, C₁₃H₁₂N₂O, N—H(anti)?O hydrogen bonds produce the so‐called urea α‐network and the N—H(syn) donor forms an unconventional N—H?π hydrogen bond.     

Extremely narrow switching fields in oriented Ba-ferrite particulate media

Oriented particulate Ba-ferrite (BF) media have been known to exhibit very narrow switching field distributions, due to a confluence of reasons based on the particle morphology and the direction of their magnetic anistropy. In this study we report on extremely narrow switching fields observed in longitudinally oriented BF rigid disk coatings, which are primarily the result of strong positive magnetostatic interactions between adjacent platelets in the oriented assemblies. In the transverse direction, the interactions are negative, and the switching fields are large.     

Reaction of O-trimethylsilylated cyanohydrins with α-bromoesters: a new synthesis of tetronic acids

Tetronic acids and β-keto-γ-butyrolactones are easily prepared by the zinc induced reaction of O-trimethylsilylated cyanohydrins and α-bromoesters.     

Method of array shape calibration based on time delay estimation using two auxiliary sources

As for a flexible horizontal array deployed in the sea, it is difficult to obtain each sensor's precise relative position. Therefore a method of array shape calibration is proposed. The method is described as follows. Firstly two separate auxiliary sources are deployed. Secondly tune delay of each sensor's received signal is estimated. Finally, with the aid of GPS location of the sources and the horizontal array, relative sensor positions of the horizontal array can be determined. The estimation of relative sensor positions is unbiased. Simultaneously, simulation analysis has been done to estimate its standard variance, and the optimal flare angle of the two sources has been derived. Data of 2001 Asian Sea International Experiment have been used to validate the method. After array calibration, measured source azimuth angle agrees with the real one, and measured array gain agrees with the theoretical gain. In conclusion, the theoretical and experimental results both show that the method can determine each sensor's relative position precisely.     

High transverse momentumη production in π− p, π+ p,andpp interactions at 280 GeV/c

The inclusive cross sections for η production by the interactions of 280 GeV/c momentum π^?, π⁺, and proton beams in hydrogen have been measured. The kinematical range covered is ?0.45<x _F <0.45, and 4.0<P _T <7.0 GeV/c for Feynmanx _F and transverse momentum respectively. The η to π⁰ cross section ratios are given for the three reactions. The ratio of π^? p to π⁺ p cross sections for η production in the above kinematic ranges is 1.22±0.08±0.11.