Two different evolutionary types of comets proved by polarimetric and infrared properties of their dust ABSTRACT Aims. We consider polarimetric and thermal-emission properties of comet dust and show how and why they can be used for classification of comets. Methods. We provide a statistical analysis of comet polarimetric, thermal, and orbital characteristics. We perform computer simulations of ...

A sample of J–type carbon stars was searched for OH maser emission. The new detection of three OH lines towards two silicate carbon stars is reported. In V778Cyg, previously known as the main–lines (1665 and 1667MHz) maser source, the satellite 1612MHz emission was discovered while in NSV2814 the main OH lines were detected. The presence of OH maser lines confirms the former suggestion that oxy...

Cement setting and cohesion are governed by the precipitation and growth of calcium-silicate-hydrate, through a complex evolution of microstructure. A colloidal model to describe nucleation, packing, and rigidity of calcium-silicate-hydrate aggregates is proposed. Polydispersity and particle size dependent cohesion strength combine to produce a spectrum of packing fractions and of corresponding...

This review reports recent advances in the field of polymer–layered silicate nano composites. Thesematerials have attracted both academic and industrial attention because they exhibit dramaticimprovement in properties at very low filler contents. Herein, the structure, preparation andproperties of polymer–layered silicate nanocomposites are discussed in general, and finally the effectof clay na...

Aluminium, the third most abundant element in the earth’s crust, occurs in nature in combination with silicon and oxygen (i.e. as aluminium silicate). When subject to tropical weathering, aluminium silicate may react to form aluminium hydroxide. Rock containing high concentrations of aluminium hydroxide is called bauxite. This rock is the usual starting material for the production of aluminium....

Years ago, the restorative material options for the dental practitioner were limited. Direct placement materials available were either amalgam or silicate. Amalgam has long been recognized as a forgiving restorative material that works well in a variety of circumstances. Advantages of amalgam include cariostatic properties, the ability to work in varied moisture conditions, and quick bulk place...

The silicon can induce beneficial changes in plants, such as the further development of tissues and increased photosynthetic rate. Thus, studies on the anatomical changes resulting from in vitro culture are key to better understanding the development of micropropagated plants. Therefore, this study was undertaken to evaluate the morphological and physiological differences in plants with the use...

A duo of primitive-silicate-bearing magmatic irons. For guidance on citations see FAQs. c [not recorded] Version: Version of Record Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online's data policy on reuse of materials please consult the policies page. Introduction: In a prev...

this article describes successful use of calcium-enriched mixture (cem) cement and biodentine in apexogenesis treatment in two 8-year-old patients, one with immature permanent molar diagnosed primarily with irreversible pulpitis and the other with partially vital maxillary central incisor. after access cavity preparation, partial pulpotomy in molar and full pulpotomy in central was performed, a...

The silicate oligomerization reaction is key to sol-gel chemistry and zeolite synthesis. Numerous experimental and theoretical studies have been devoted to investigating the physical chemistry of silicate oligomers in the prenucleation stage of siliceous zeolite formation. Most of the previous quantum chemical computational work has used gas phase models or continuous solvent models for silica ...