The systematic modification of the surface charge of lignocellulose fibers was performed with a polyelectrolyte layer-by-layer (LbL) nanocoating process to produce negatively and positively charged fibers. The fibers were coated with 20-50 nm thick polymer surface layers which subsequently increased interaction between the fibers during paper formation. The modified fibers were added to standard fibers at varying proportions to produce paper with corresponding variation in properties such as strength and electrical conductivity. Paper strength was doubled by manipulating the surface charge and coating thickness of the LbL-treated pulp fibers. It is demonstrated that the LbL coating process increased the fiber interactions and that these interactions enhanced the paper properties. This process, when applied to a simulated sample of recycle grade of fibers, produce paper with an increase in tear strength as compared with untreated fiber paper. Nanocoating fibers with polythiophene/polyallylamine multilayers produced marginally conductive pulp and paper. Paper electrical conductivity was proportional to the number of the bilayers deposited.

Observations have been made of the local atmospheric pressure field and the long-period seismic noise fields both on the surface of the Earth and in a mine at a depth of 183 metres. The observations show that during windy intervals and in the period range 20-100 s there is a strong correlation between local atmospheric pressure changes and the noise recorded by a vertical seismograph located on the surface. In contrast, over the same range of periods there is no correlation between the seismic noise recorded in the mine and local atmospheric pressure changes except during the passage of acoustic waves. It is shown that the noise in this pass band is not due to the buoyant response of the seismograph, but is caused by the motion of the Earth responding to atmospheric pressure changes.

A laboratory study of the effects of oriented pennyshaped inclusions embedded in a solid matrix on the propagation of seismic shear waves shows good agreement with theoretical predictions for some polarizations and poor agreement for polarizations at large crack densities. The models are constructed of solid matrix of epoxy resin with inclusions of thin rubber discs of approximately equal cross-sectional areas. The theoretical basis for these experiments is the theory of Hudson, in which the wavelength is greater than the dimensions of the individual cracks and their separation distance, and the cracks are in dilute concentration. By a pulse transmission method, seismograms were gathered in models free of inclusions and models with inclusions. Seismic measurements of velocity anisotropy, for variations in both a polarization and propagation direction, were performed on physical models with inclusions (cracks) representing five different crack densities (1, 3, 5, 7, and 10 percent). Variations in velocity anisotropy at different crack densities have been evaluated by using Thomsen’s parameter (γ) which relates velocities to their elastic constants, [Formula: see text]. Comparisons between experimental and theoretical results indicate that with the waves polarized parallel to the aligned inclusions, [Formula: see text] agree well with the theoretical model. However, shear waves for the same propagation direction but polarized perpendicular to the plane containing the inclusions [Formula: see text] produced results that agree well with the theory for crack densities up to 7 percent, but disagree for higher crack densities. The deviation of γ at 10 percent crack density suggests that crack‐crack interaction and their coalescence may be observable and could lead to seismic techniques to differentiate between microcracks and larger macrocracks.