A composition for preparing a rigidified fabric made of heat resistant fibers or threads of heat resistant fibers, preferably of woven threads made of heat resistant fibers, said composition comprising a mixture of a product A and a product B, the product A being obtained by polymerisation of carbohydrate units, natural or synthetic, preferably a saccharide, and more preferably a sugar such as glucose, fructose, galactose, sucrose, maltose, lactose, etc.; and the product B consisting of at least one additive such as a binding agent. A method for preparing said composition, a method for preparing a rigidified fabric of heat resistant fibers, the method for the manufacture of filtering devices, filtering devices so obtained, their use for the filtering of metal, and installation and process involving said filtering devices.

Coated optical fibers and uses of such fibers as sensors in high temperature and/or high pressure environments. The coated optical fiber has improved sensing properties at elevated pressure and/or temperature, such as enhanced acoustic sensitivity and/or a reduced loss in acoustic sensitivity. The use of the coated optical fibers in various sensing applications that require operation under elevated pressure and/or temperature, such as, acoustic sensors for various geological, security, military, aerospace, marine, and oil and gas applications are also provided.

An optical fiber comprises a glass fiber which comprises a core and a cladding, a primary resin coating layer which covers the periphery of the glass fiber, and a secondary resin coating layer which covers the periphery of the primary resin coating layer. The glass fiber is a multimode fiber having a core diameter of 40-60 m and a cladding diameter of 90-110 m, and the primary resin coating layer is a layer formed by curing a curable resin composition which comprises oligomers, monomers, and a reaction initiator, the curable resin composition containing a one-end-capped oligomer in an amount of 30% by mass or larger based on all the oligomers.

A Hydrocarbyl Carboxybetaine represented by Formula (1) is provided:

##STR00001##

wherein, n.sub.10 and n.sub.2>0, A is a C1-C20 alkyl group when n.sub.1>0, and A is a single bond when n.sub.1=0. R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are each independently selected from hydrogen atom, deuterium atom, C1-C20 alkyl group, C2-C20 alkenyl group and C2-C20 alkynyl group; X is selected from SH, SOCH.sub.3, SCH.sub.3, NH.sub.2, SiCl.sub.3, Si(OCH.sub.3).sub.3, Si(OCH.sub.2CH.sub.3).sub.3,

##STR00002##