6,533 research outputs found
The colloidal chemistry of ceramic clays
The colloidal chemistry and mineralogy of two argil minerals were studied. Deposits of kaolin and of ceramic clays in the United States and England are discussed for the probable mechanism of formation. The structural modifications of the bed, original material associated with the clays and the proper use of flocculants are discussed
The role of water in slip casting
Slips and casting are considered in terms of physical and colloidal chemistry. Casting slips are polydisperse suspensions of lyophobic particles in water, whose degree of coagulation is controlled by interaction of flocculating and deflocculating agents. Slip casting rate and viscosity are functions of temperature. Slip rheology and response to deflocculating agents varies significantly as the kinds and amounts of colloid modifiers change. Water is considered as a raw material. Various concepts of water/clay interactions and structures are discussed. Casting is a de-watering operation in which water moves from slip to cast to mold in response to a potential energy termed moisture stress. Drying is an evaporative process from a free water surface
Laser phase noise effects on the dynamics of optomechanical resonators
We investigate theoretically the influence of laser phase noise on the
cooling and heating of a generic cavity optomechanical system. We derive the
back-action damping and heating rates and the mechanical frequency shift of the
radiation pressure-driven oscillating mirror, and derive the minimum phonon
occupation number for small laser linewidths. We find that in practice laser
phase noise does not pose serious limitations to ground state cooling. We then
consider the effects of laser phase noise in a parametric cavity driving scheme
that minimizes the back-action heating of one of the quadratures of the
mechanical oscillator motion. Laser linewidths narrow compared to the decay
rate of the cavity field will not pose any problems in an experimental setting,
but broader linewidths limit the practicality of this back-action evasion
method.Comment: 9 pages, 7 figure
Stories of Women in Self-Defense
Book Revie
Sustainable Grazing in the Channel Country Floodplains. A technical report on findings between June 1999 and August 2002
The project "Sustainable Grazing in the Channel Country Floodplains" was initiated by the cattle industry to document the current knowledge of the Channel Country, to address gaps in existing research and to ensure the use of sustainable grazing practices within the floodplains. The Natural Heritage Trust, Meat and Livestock Australia, cattle producers and state agencies provided funding between 1998 and 2002. Current knowledge was documented through 39 members of the grazing community contributing a total of 641 years combined experience of natural resource management. Seventeen on-going soil and pasture monitoring sites provided detailed soil moisture and nutrient levels as well as pasture yield and nutrient levels. This information has led to the development of prototype tools to enhance natural resource management decisions. The publications resulting from this work have allowed land managers new to the Channel Country to quickly understand the accepted industry management practices. The knowledge documented within the project is also of interest to the broader community who have a desire to better understand Lake Eyre and its major river systems, and who wish to ensure the sustainable management of the unique natural resources within the Channel Country
A Sensitive Faraday Rotation Setup Using Triple Modulation
The utilization of polarized targets in scattering experiments has become a
common practice in many major accelerator laboratories. Noble gases are
especially suitable for such applications, since they can be easily
hyper-polarized using spin exchange or metastable pumping techniques. Polarized
helium-3 is a very popular target because it often serves as an effective
polarized neutron due to its simple nuclear structure. A favorite cell material
to generate and store polarized helium-3 is GE-180, a relatively dense
aluminosilicate glass. In this paper, we present a Faraday rotation method,
using a new triple modulation technique, where the measurement of the Verdet
constants of SF57 flint glass, pyrex glass, and air were tested. The
sensitivity obtained shows that this technique may be implemented in future
cell wall characterization and thickness measurements. We also discuss the
first ever extraction of the Verdet constant of GE-180 glass for four
wavelength values of 632 nm, 773 nm, 1500 nm, and 1547 nm, whereupon the
expected 1/{\lambda}^{2} dependence was observed.Comment: 4 pages, 2 figures Updated version for RSI submissio
Tunable Transient Decay Times in Nonlinear Systems: Application to Magnetic Precession
The dynamical motion of the magnetization plays a key role in the properties
of magnetic materials. If the magnetization is initially away from the
equilibrium direction in a magnetic nanoparticle, it will precess at a natural
frequency and, with some damping present, will decay to the equilibrium
position in a short lifetime. Here we investigate a simple but important
situation where a magnetic nanoparticle is driven non-resonantly by an
oscillating magnetic field, not at the natural frequency. We find a surprising
result that the lifetime of the transient motion is strongly tunable, by
factors of over 10,000, by varying the amplitude of the driving field.Comment: EPL Preprin
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