P a t e n t s

Membrane for gas transport The p h e n o m e n o n o f 'B rown ian motion ' is well known, in which colloidal par t ic les can be seen to move in a con t inuous zigzag course a s a r e su l t of coll is ions with the molecules of the su spend ing liquid. A s imi lar r a n d o m movement of molecules also t akes place in homogenous l iquids a n d gases . The energy of th ls mot ion is p u t to work in this invention.

The propos i t ion is simple: an asymmet r i c m e m b r a n e is cons t ruc ted in which the t ransverse pores are conical in shape a n d in which the or ienta t ion of the cones is consis tent . The m e m b r a n e is p laced in a conta iner full of gas or liquid. One or more componen t s in the fluid flow preferent ia l ly across the membrane , from the nar rower to the wider ends of the pores.

In tes t s u s ing this type of m e m b r a n e to med ia te the supp ly of gas to a m a s s spect rometer , it was found tha t a pu l se of a rgon reached the i n s t r u m e n t more quickly when allowed to cross such a m e m b r a n e t h a n when s imple diffusion was permi t ted . The in te rpre ta t ion p u t on th is f inding is tha t the m e m b r a n e ' pumps ' the gas. The m e m b r a n e s u sed in th is tes t were polyethylene shee t 0 ,008 cm thick, in which the conical pores had a sma l l e r - end d iamete r of 0.001 cm. Other su i tab le mate r i a l s inc lude th in a l u m i n i u m sheet or o ther soft metal . Multiple m e m b r a n e s in ser ies can ac t a s f rac t ionat ion columns.

Patent number: US 5316568 Date: 31 May 1994 Inventor and applicant: M.H. Brown

Corkscrew aids filtration This p a t e n t c la ims improved separa t ion of two phases , one con t inuous a n d one d ispersed , by centr i fugal effects in a helicoidal flow. The a p p a r a t u s iS of sufficiently high capac i ty and

efficiency to be useful in the food, pharmaceu t i ca l , biomedical , water t r ea tmen t and pe t ro leum indust r ies .

A tubu la r m e m b r a n e is encased by a container. A feed delivers l iquid to the m e m b r a n e - e n c o m p a s s e d volume. Leachate collects in voids between the m e m b r a n e a n d the container, a n d can be d ra ined away. Reta ined mate r ia l can also be d ra ined from the m e m b r a n e volume. The m e m b r a n e volume also conta ins a he l lx - shaped guide which is fixed to a centra l solid rod. Liquid is t hus forced to travel in a helicoidal route down the m e m b r a n e volume. The centr ifugal force genera ted in this way enhances the act ion of filtration.

Patent number: EP 596764 Date: I I May 1994 Inventors: I. Prevost, A. Rojey Applicant: Ins t i tu t F ranca l s du Petrole

Leak detection Fai lures of hollow fibres or in the mate r ia l s u sed to seal or 'pot ' them need to be detected accurate ly . Various me thods are available, such as p r e s su re t es t s us ing air, or r everse -p ressure tes t s to expand, then deflate the s o u n d fibres.

This invention, pa ten ted (so far) in J a p a n and France in quick success ion, p ressu r i zes the cas ing which conta ins the hollow fibres. The pressur iz ing gas conta ins finely-divided part icles . If a fibre or the pot t ing compound h a s a leak, the gas and en t ra ined par t ic les will escape. If a laser is d i rected a t the ends of the casing, the par t ic les will reflect the beam and disclose the precise origin (fibres a n d / o r pot t ing compound) of any leaks.

Patent numbers: JP 6134268, FR 2698693 Dates: 17 May 1994, 3 J u n e 1994 Inventor: H. Nagash ima Applicant: NOK Corp.

Siloxane--crown ether adduct The sol id-s ta te m e m b r a n e descr ibed here Is an a d d u c t

be tween a crown ether a n d a heteropolysfloxane, and a lso con ta ins ions such as plcrate or f luoroborate. These mate r i a l s have been u sed before, bu t u sua l ly a s suppo r t ed l iquid m e m b r a n e s which are fragile and prone to leaching a n d other degradat ions . The crown ether ac ts a s a carr ier of a s t rong organic acid. The m e m b r a n e is useful in d ia lys is a n d other separa t ions , and is par t i cu la r ly efficient a t t r anspor t ing p o t a s s i u m ions.

Patent number: EP 601942 Date: 15 J u n e 1994 Inventors: D. Wettling, C. Lurin, P.I.L. Lacan, C. Gulzard Appllcan~ E a s t m a n Kodak Co.

New blood compatible materials The polymers which form the novelty in th is invention are po lye ther -po lyamide block copolymers in which the hea t of crysta l l izat ion is no more than 30 J / g and which show plas t ic i ty when heated. Other vers ions of these copolymers a re a l ready known, b u t those b a s e d on a l iphat ic po lyamides are not sat isfactory: the s t rong in te rmolecular forces tend to make the crystal l ine s ta te the preferred s ta te a n d otherwise limit the appl ica t ions in membranes .

It ha s been found tha t the hea t of crysta l l izat ion is a useful indica tor of the forces of in te rmolecular cohesion. Aromat ic or alicycllc polyamides are chosen to reac t wlth polyethylene oxide, polypropylene oxide or t e t ramethy lene oxlde--ethylene oxide copolymer.

The polymers are useful in haemodia lys is , artificial kidneys, oxygenators , blood filters, blood bags, ca the te r s a n d artificial blood vessels.

Patent number: EP 600793 Date: 8 J u n e 1994 Inventors: A. Mochlzukl, T. Nakazaki , K. Hadano-sh i Appllcan~ Terumo K.K.

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