A method of preparing a light stabilized antimicrobial material, characterised in that the method comprises the steps of:
(a) preparing a solution comprising an
organic solvent and a source of silver in a quantity sufficient to provide a desired silver concentration in said material;
(b) subjecting a material which includes gel-forming fibres containing one or more hydrophilic, amphoteric or anionic polymers to said solution for a time sufficient to incorporate said desired silver concentration into said polymer, wherein said polymer comprises a polysaccharide or modified polysaccharide, a polyvinylpyrrolidone, a polyvinyl alcohol, a polyvinyl ether, a polyurethane, a polyacrylate, a polyacrylamide, collagen, or gelatin or mixtures thereof; and
(c) subjecting said polymer, during or after step (b) to one or more agents selected from the group consisting of ammonium salts, thiosulphates, chlorides and peroxides which facilitate the binding of said silver on said polymer, the agent being present in a concentration between 1% and 25% of the total volume of treatment, which material is substantially photostable upon drying, but which will dissociate to release said silver upon rehydration of said material.
|How to round up cats|
“First, the scope of any such claim must be exactly the same whether one is considering infringement or validity.
Secondly, there can be no justification for using rounding or any other kind of approximation to change the disclosure of the prior art or to modify the alleged infringement.
Thirdly, the meaning and scope of a numerical range in a patent claim must be ascertained in light of the common general knowledge and in the context of the specification as a whole.
Fourthly, it may be the case that, in light of the common general knowledge and the teaching of the specification, the skilled person would understand that the patentee has chosen to express the numerals in the claim to a particular but limited degree of precision and so intends the claim to include all values which fall within the claimed range when stated with the same degree of precision.
Fifthly, whether that is so or not will depend upon all the circumstances including the number of decimal places or significant figures to which the numerals in the claim appear to have been expressed.”
|Merpel is often prone to a little rounding|
As mentioned above, in comparable situations much of the UK caselaw directs a construction based on accuracy to significant figures, rather than a “whole numbers” approach. However, there is something of a “mathematical quirk” with this particular range claimed. As explained at the first trial, the range 1% to 25% using the significant figures approach encompasses numbers within the range ≥ 0.95% and < 25.5%. It is only the whole number 1 and powers of the number 10 to which such an asymmetrical range applies though; if the bottom of the claimed range had been 2% rather than 1%, even when applying the significant figures approach, the claim would have included all values ≥ 1.5 and < 25.5, a more broadly symmetrical distribution.
This Kat was completely convinced by Birss J’s erudite reasoning and finds himself surprised that the Court of Appeal felt unable to endorse it. He is troubled by a reasoning that considers that 1 as a lower limit of a range in a claim can actually mean 0.5. From the comments on Jeremy's post, it seems that some readers are likewise uncomfortable with the Court of Appeal decision. He was particularly taken with the point that both judgments (but the appeal decision more than the first instance) can be seen to focus on the mathematical conventions, rather than what a chemist would think about the claimed range. (This view is expanded in a piece on the PatLit blog, which also criticises the Court of Appeal decision in Actavis v Lilly.) What view do the rest of our readers take?