摘要:
A light emitting device and method for making the same is disclosed. The light-emitting device includes an active layer sandwiched between a p-type semiconductor layer and an n-type semiconductor layer. The active layer emits light when holes from the p-type semiconductor layer combine with electrons from the n-type semiconductor layer therein. The active layer includes a number of sub-layers and has a plurality of pits in which the side surfaces of a plurality of the sub-layers are in contact with the p-type semiconductor material such that holes from the p-type semiconductor material are injected into those sub-layers through the exposed side surfaces without passing through another sub-layer. The pits can be formed by utilizing dislocations in the n-type semiconductor layer and etching the active layer using an etching atmosphere in the same chamber used to deposit the semiconductor layers without removing the partially fabricated device.
摘要:
A light emitting device and method for making the same is disclosed. The light-emitting device includes an active layer sandwiched between a p-type semiconductor layer and an n-type semiconductor layer. The active layer emits lights when holes from the p-type semiconductor layer combine with electrons from the n-type semiconductor layer therein. The active layer includes a number of sub-layers and has a plurality of pits in which the side surfaces of a plurality of the sub-layers are in contact with the p-type semiconductor material such that holes from the p-type semiconductor material are injected into those sub-layers through the exposed side surfaces without passing through another sub-layer. The pits can be formed by utilizing dislocations in the n-type semiconductor layer and etching the active layer using an etching atmosphere in the same chamber used to deposit the semiconductor layers without removing the partially fabricated device.
摘要:
Flexible polyurethane foams are made using certain hydrolysable silane compounds in the foam formulation. The hydrolysable silane compounds contain at least one isocyanate-reactive group and at least one hydrolysable silane group. The presence of the hydrolysable silane compound in the foam formulation leads to improved tensile, tear and elongation properties without an adverse effect on other important foam properties such as resiliency and hysteresis loss.
摘要:
Moisture curable compositions including silylated polymers and methods for producing the same are provided. A two component moisture curable system for producing a cured or cross-linked silylated polymer having improved compression set properties is provided. The two component system comprises a first formulation and a second formulation. The first formulation comprises a silylated polymer, water, and filler and the second formulation comprises the silylated polymer, a curing catalyst comprising at least one Brønsted acid, and a moisture scavenger. The final cured formulation may have a compression set, determined by ASTM D395 or ISO 815-1, of less than 100%, and in some examples less than 50% and in some examples less than 15%. This demonstrated improvement in compression set not only allows the silylated polymers to be used in applications where cyclic loads are applied but also enhances product durability.
摘要:
Methods of producing a composition comprising a crosslinkable silane-terminated polymer having at least one crosslinkable silyl group in each molecule are provided. The method may comprise providing a polymer having at least one unsaturated group and at least one alcohol hydroxyl group in each molecule and having a number average molecular weight between about 100 and about 5,000, adding to the polymer a compound having a hydrogen-silicon bond and a crosslinkable silyl group in each molecule and a hydrosilylation catalyst to thereby carry out a hydrosilylation reaction to form a composition comprising hydrosilylated polymers, wherein the hydrosilylation reaction has a hydrosilylation efficiency greater than 50% as determined by 1H-NMR, capping the hydrosilylated polymers by adding the hydrosilylated polymer to at least one isocyanate at an index of between about 100 and about 250, and reacting the isocyanate capped hydrosilylated polymer with a polyol having a nominal functionality of at least 2 to form the composition comprising a crosslinkable silane-terminated polymer.
摘要:
Embodiments of the invention provide for methods of producing a composition comprising a crosslinkable silane-terminated polymer having at least one crosslinkable silyl group in each molecule. The method comprises providing a polymer having at least one unsaturated group and at least one alcoholic hydroxyl group in each molecule, adding to the polymer a compound having a hydrogen-silicon bond and a crosslinkable silyl group in each molecule and a hydrosilylation catalyst to thereby carry out a hydrosilylation reaction to form a composition comprising hydrosilylated polyoxyalkylene polymers, reacting the hydrosilylated polyoxyalkylene polymers with at least one isocyanate in the presence of a first tin-free catalyst to form an isocyanate reacted hydrosilylated polymer, and optionally reacting the isocyanate reacted hydrosilylated polymer with a polyol having a nominal functionality of at least 2 to form a polyol reacted crosslinkable silane-terminated polymer.
摘要:
Embodiments of the invention provide for compositions including a crosslinkable silane-terminated polymer having at least one crosslinkable silyl group in each molecule. The crosslinkable silane-terminated polymer comprises a reaction product of at least a isocyanate capped hydrosilylated polymer and a polyol having a nominal functionality of at least 2 which is at least one of a polycarbonate polyol, a natural oil based polyol, a polyoxyalkyleneamine, a difunctional aromatic amine, a polybutyloxide polyether polyol, and a polytetramethylene glycol.
摘要:
Embodiments of the invention provide for methods of producing a composition comprising a crosslinkable silane-terminated polymer having at least one crosslinkable silyl group in each molecule. The method comprises providing a polymer having at least one unsaturated group and at least one alcoholic hydroxyl group in each molecule, adding to the polymer a compound having a hydrogen-silicon bond and a crosslinkable silyl group in each molecule and a hydrosilylation catalyst to thereby carry out a hydrosilylation reaction to form a composition comprising hydrosilylated polyoxyalkylene polymers, reacting the hydrosilylated polyoxyalkylene polymers with at least one isocyanate in the presence of a first tin-free catalyst to form an isocyanate reacted hydrosilylated polymer, and optionally reacting the isocyanate reacted hydrosilylated polymer with a polyol having a nominal functionality of at least 2 to form a polyol reacted crosslinkable silane-terminated polymer.
摘要:
A method of performing parallel image reconstruction of undersampled image data in k-space. A defined partitioning of a k-space region into a plurality of segments is received. A segment of the plurality of segments is identified wherein data is sampled at less than a Nyquist rate. First imaging data is sampled at the Nyquist rate. A reconstruction coefficient is calculated for at least a portion of the identified segment using the sampled first imaging data. Second imaging data is sampled at less than the Nyquist rate. A value for a missing k-space sample in the identified segment is predicted using the calculated reconstruction coefficient and the sampled second imaging data. An image of the image area is defined using the predicted value and the received second dataset.
摘要:
A method of performing parallel image reconstruction of undersampled image data in k-space. A defined partitioning of a k-space region into a plurality of segments is received. A segment of the plurality of segments is identified wherein data is sampled at less than a Nyquist rate. First imaging data is sampled at the Nyquist rate. A reconstruction coefficient is calculated for at least a portion of the identified segment using the sampled first imaging data. Second imaging data is sampled at less than the Nyquist rate. A value for a missing k-space sample in the identified segment is predicted using the calculated reconstruction coefficient and the sampled second imaging data. An image of the image area is defined using the predicted value and the received second dataset.