A method of forming a porous three-dimensional (3D) is disclosed. The method comprises (I) printing a first composition on a substrate (16) with the nozzle (12) of the apparatus (10) to form at least one first filament (14) comprising the first composition, (II) selectively controlling the distance and/or the speed such that the at least one first filament coils on the substrate to give a first layer on the substrate, the first layer comprising a coiled filament, optionally repeating steps I) and II) with independently selected composition(s) for any additional layer(s), and (III) exposing the layer(s) to a solidification condition. A porous three-dimensional (3D) article formed in accordance with the method is also disclosed.

Disclosed are complexes and methods of using the complexes as catalysts for addition of amines to unsaturated electrophiles, as well as novel compounds produced by the disclosed complexes and methods. The disclosed methods may utilize the disclosed complexes as catalysts for adding unprotected primary amines and secondary amines to unsaturated electrophiles in an enantioselective manner to produce novel compounds which may include amino substituted succinimide compounds.

Provided are a chromium catalyst precursor, an ethylene oligomerization catalyst including the same, and a method of preparing an ethylene oligomer using the same. More particularly, a chromium catalyst precursor which may oligomerize ethylene with high activity and high selectivity in spite of not using methylaluminoxane (MAO) or modified-methylaluminoxane (MMAO), an oligomerization catalyst including the same, and a method of preparing an ethylene oligomer using the same are provided.

The invention relates to a method of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising step (i): (i) reacting the first olefin with the second olefin in the presence of a compound that catalyzes said metathesis reaction such that the molar ratio of said compound to the first or the second olefin is from 1:500 or less, and the conversion of the first or the second olefin to said olefin is at least 50%, characterized in that as compound that catalyzes said metathesis reaction a compound of the following formula is used:

##STR00001## wherein M is Mo or W; R.sup.1 is aryl, heteroaryl, alkyl, or heteroalkyl; optionally substituted; R.sup.2 and R.sup.3 can be the same or different and are hydrogen, alkyl, alkenyl, heteroalkyl, heteroalkenyl, aryl, or heteroaryl; optionally substituted; R.sup.5 is alkyl, alkoxy, heteroalkyl, aryl, heteroaryl, silylalkyl, silyloxy, optionally substituted; and R.sup.4 is a residue R.sup.6X, wherein X=O and R.sup.6 is aryl, optionally substituted; or X=S and R.sup.6 is aryl, optionally substituted; or X=O and R.sup.6 is (R.sup.7, R.sup.8, R.sup.9)Si; wherein R.sup.7, R.sup.8, R.sup.9 are alkyl or phenyl, optionally substituted; or X=O and R.sup.6 is (R.sup.10, R.sup.11, R.sub.12)C, wherein R.sup.10, R.sup.11, R.sup.12 are independently selected from phenyl, alkyl; optionally substituted; and to the catalysts used in the method.

The present disclosure provides bridged metallocene catalyst compounds comprising SiSi bridges, catalyst systems comprising such compounds, and uses thereof. Catalyst compounds of the present disclosure can be hafnium-containing compounds having one or more cyclopentadiene ligand(s) substituted with one or more silyl neopentyl groups and linked with an SiSi-containing bridge. In another class of embodiments, the present disclosure is directed to polymerization processes to produce polyolefin polymers from catalyst systems comprising one or more olefin polymerization catalysts, at least one activator, and an optional support.

Disclosed is a novel transition metal compound that exhibits excellent catalytic activity in polyethylene polymerization and is useful for preparing polyethylene having a high intramolecular short-chain branch content without deteriorating physical properties such as molecular weight, melting point, and density; a catalyst composition comprising the same; and a method for preparing polyethylene using the same.

The subject of the present invention is the use, as hydrosilylation and/or dehydrogenative silylation catalyst, of a cobalt compound of formula (1): [CO(N(SiR.sub.3).sub.2).sub.x].sub.y in which: the R symbols, which are identical or different, represent a hydrogen atom or a hydrocarbon-based radical having from 1 to 12 carbon atoms, and preferably the R symbols, which are identical or different, are chosen from the group consisting of: a hydrogen atom, alkyl groups having from 1 to 8 carbon atoms and aryl groups having from 6 to 12 carbon atoms, x=1, 2 or 3 andy=1 or 2.

Novel, lubricious coatings for medical devices are disclosed. The coatings provide improved lubricity and durability, and are readily applied in coating processes. The present invention is also directed to a novel platinum catalyst for use in such coatings. The catalyst provides for rapid curing, while inhibiting cross-linking at ambient temperatures, thereby improving the production pot life of the coatings.

The present invention concerns a method for the hydrosilylation of an unsaturated compound comprising at least one ketone function, one aldehyde function, one alkene function and/or one alkyne function, with a compound comprising at least one hydrogen-silyl function implementing an organic catalyst of tri-coordinated germanium.

Method of making an immobilized tungsten catalyst comprising or consisting of (SiO).sub.X W(O)(CR.sup.1R.sup.2)(R.sup.3 or R.sup.4).sub.2-x(L).sub.z, comprising at least the following step (i): (i) reacting silica (Si02) with a tungsten oxo alkylidene complex comprising or consisting of (R.sup.3)(R.sup.4)W(O)(CR.sup.1R.sup.2)(L).sub.y, preferably wherein CR.sup.1R.sup.2 is selected from CHC(CH.sub.3).sub.3 or CH(C(CH.sub.3).sub.2)C.sub.6H.sub.5 and R.sup.3 and R.sup.4 are independently selected from pyrrol-1-yl, 2,5-dimethylpyrrol-1-yl, or 2,5-diphenylpyrrol-1-yl, or OR, wherein R is a six membered or 10 membered aryl ring, optionally substituted.