Second harmonic generation (SHG) is applied for the first time to study the surfaces of clay particles. An SHG signal was detected from an aqueous suspension of disk-shaped montmorillonite clay particles of 0.5 μm diameter and 0.01 μm thickness. The origin of the SHG signal is the polarization of water molecules by surface charges located in the edge region of the clay particles. On addition of...

Pillared clays (PILCs) are interesting materials mostly due to their high basal spacing and surface area, which make them suitable for adsorption and catalysis applications, for example. However, the production of these materials on industrial scale is dependent on research about what parameters influence the process. Thus, the objective of this work was to evaluate what parameters influence th...

Clay mineral studies in the U.S.S.R., mainly since 1960, are summarized. Electron diffraction techniques especially have been developed and used extensively. Methods have been developed for simultaneous recording of DTA curves and other properties. Polytypism of phyllosilicates has been studied intensively by Zvyagin and others. Mucfi new information on the structure and morphology of halloysit...

Isolated patches of white clay occurring in the terminal moraine of Long Island, Staten fsland, and southern New Jersey have been mentioned in a number of geologic descriptions. Such an occurrence was recently encountered during excavation for a building site and samples were submitted to the mineralogical laboratory of Columbia University for identification by Messrs. Schoonmaker and Kirkman. ...

B. B. Basak, Sharmistha Pal and S. C. Datta* Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi 110 012, India Present address: Directorate of Medicinal and Aromatic Plant Research, Boriavi, Anand 387 310, India Present address: Central Soil and Water Conservation Research and Training Institute, Research Centre, Madhya Marg, Chandigarh 160 01...

The Soil Series It is frequently possible to encounter, in a very limited area, almost the whole range of every soil property: from soil reaction values of pH 3.5 to pH 9.0, from structureless to very strongly structured, from sands to clays, from impermeable to excessively permeable materials etc. It has been one of the main objectives of the pedologist to classify this seemingly incomprehensi...

Clays have been used in southern Africa as photoprotectants by the indigenous people. Typically, two types of clay are used: one white in colour and the other red. In this work, the two clays were identified and characterized, and their in vitro SPF values measured. The clays afford a low SPF but offer broad-spectrum protection. No cutaneous side effects from the use of these clays are known. F...

Scaling relationships are identified between NMR longitudinal relaxation times and clay dispersion quality in polymer-paramagnetic clay nanocomposites. Derived from a previously published analytical relationship developed from a lamella-based model, the scaling relationships are based on the enhancement of NMR relaxation rates with increasing exfoliation and dispersion homogeneity. The paramagn...