Abstract: In one aspect, the present disclosure describes ultrasmall gas vesicle compositions comprising modified gas vesicle shell proteins. Also disclosed herein are polynucleotide sequences which encode such compositions. Methods of treatment comprising administering such gas vesicle compositions are also provided.

Abstract: A process for forming a new group of siloxane-based compositions by a one-step co-hydrolysis and the compositions formed thereof. The siloxane-based compositions being functionalized with a carbon-carbon double (C?C) bond and a silicon-hydrogen (Si—H) bond. The C?C bond and hydrogen (H) each being attached directly to a silicon (Si) atom of the silicon-oxygen (Si—O) backbone of the siloxane-based composition. The C?C bond may be from a vinyl or an aromatic radical like a phenyl substituent. The C?C bond substituent provides the functionality needed for forming crosslinkages through standard dehydrocoupling catalysts without the need for siloxane fluids or organic compounds containing alkyl or aryl functional groups. The process provides for varying proportions of silanes as starting monomers to tailor the desired silicon, carbon, hydrogen and oxygen ratios in the siloxane-based compositions or resins.

Abstract: The invention provides branched copolymers as precursors for preparing silicon carbide (SiC) ceramics represented by the general formulae: [Si(˜)RC(˜)H]xn[SiR1R2CH2]yn,??Formula Type-I wherein n is the degree of polymerization, 0.1?x<0.8, 0.2?y<0.9 and x+y=1; and R=methyl or H, R1 and R2 are randomly composed of hydrogen (H), allyl, methyl (Me), phenyl (Ph), propargyl or vinyl. Another branched copolymer is represented by the general formula: [Si(˜)RC(˜)H]xn[SiR1R2CH2]yn[SiR3R4CH2]zn??Formula Type-II wherein n is the degree of polymerization, 0.1?x<0.8, 0?y<0.8, 0.2?z<0.8 and x+y+z=1; and R=methyl or H, R1 and R2 are randomly composed of hydrogen (H), methyl (Me) and phenyl; R3 and R4 are randomly composed of H, allyl, methyl, phenyl (Ph), propargyl, and vinyl. The invention also provides methods for the preparation of such branched copolymers.

Abstract: A process for preparing a cyclic organosilane using a solvent that promotes ring-closure reactions between an organosilane compound and a dihalo organic compound is disclosed. The ring-closure reactions may form a 4-, 5- or 6-member cyclic organosilane. The process involves a mixture including a dihalo organic compound, an organosilane having at least two functional groups, a solvent and magnesium (Mg). The two functional groups in the organosilane may include halogen, alkoxy or a combination thereof. In the presence of Mg, a Grignard intermediate is formed from the dihalo organic compound in the mixture. The solvent favors intra-molecular or self-coupling reactions of the Grignard intermediate. The intra-molecular or self-coupling reaction promotes ring-closure reaction of the Grignard intermediate to form the cyclic organosilane.

Abstract: A process for forming a new group of siloxane-based compositions by a one-step co-hydrolysis and the compositions formed thereof. The siloxane-based compositions being functionalized with a carbon-carbon double (C?C) bond and a silicon-hydrogen (Si—H) bond. The C?C bond and hydrogen (H) each being attached directly to a silicon (Si) atom of the silicon-oxygen (Si—O) backbone of the siloxane-based composition. The C?C bond may be from a vinyl or an aromatic radical like a phenyl substituent. The C?C bond substituent provides the functionality needed for forming crosslinkages through standard dehydrocoupling catalysts without the need for siloxane fluids or organic compounds containing alkyl or aryl functional groups. The process provides for varying proportions of silanes as starting monomers to tailor the desired silicon, carbon, hydrogen and oxygen ratios in the siloxane-based compositions or resins.

Abstract: The invention provides branched copolymers as precursors for preparing silicon carbide (SiC) ceramics represented by the general formulae: [Si(˜)RC(˜)H]xn[SiR1R2CH2]yn,Formula Type-I wherein n is the degree of polymerization, 0.1?x<0.8, 0.2?y<0.9 and x+y=1; and R=methyl or H, R1 and R2 are randomly composed of hydrogen (H), allyl, methyl (Me), phenyl (Ph), propargyl or vinyl. Another branched copolymer is represented by the general formula: [Si(˜)RC(˜)H]xn[SiR1R2CH2]yn[SiR3R4CH2]znFormula Type-II wherein n is the degree of polymerization, 0.1?x<0.8, 0?y<0.8, 0.2?z<0.8 and x+y+z=1; and R=methyl or H, R1 and R2 are randomly composed of hydrogen (H), methyl (Me) and phenyl; R3 and R4 are randomly composed of H, allyl, methyl, phenyl (Ph), propargyl, and vinyl. The invention also provides methods for the preparation of such branched copolymers.

Abstract: The compound 2,4,6-trimethyl-2,4,6-trisila heptane, the preparation thereof, and the use thereof as a silicon carbide precursor in chemical vapor deposition and infiltration procedures are disclosed.

Abstract: The compound 2,4,6-trimethyl-2,4,6-trisila heptane, the preparation thereof, and the use thereof as a silicon carbide precursor in chemical vapor deposition and infiltration procedures are disclosed.

Abstract: The invention provides branched copolymers as precursors for preparing silicon carbide (SiC) ceramics represented by the general formulae: [Si(˜)RC(˜)H]xn[SiR1R2CH2]yn,??Formula Type-I wherein n is the degree of polymerization, 0.1?x<0.8, 0.2?y<0.9 and x+y=1; and R=methyl or H, R1 and R2 are randomly composed of hydrogen (H), allyl, methyl (Me), phenyl (Ph), propargyl or vinyl. Another branched copolymer is represented by the general formula: [Si(˜)RC(˜)H]xn[SiR1R2CH2]yn[SiR3R4CH2]zn??Formula Type-II wherein n is the degree of polymerization, 0.1?x<0.8, 0?y<0.8, 0.2?z<0.8 and x+y+z=1; and R=methyl or H, R1 and R2 are randomly composed of hydrogen (H), methyl (Me) and phenyl; R3 and R4 are randomly composed of H, allyl, methyl, phenyl (Ph), propargyl, and vinyl. The invention also provides methods for the preparation of such branched copolymers.