Boron-containing organosilane polymers and ceramic materials thereof

The present invention relates to a polyorgano borosilane ceramic precursor polymer comprising a plurality of repeating units of the formula: (R(sup 1) single bond B)(sub p) being linked together at B by second units of the formula: single bond (R sup 2) single bond (Si single bond R sup 3) single bond (sub q), where R(sup 1) is a lower alkyl, cycloalkyl, phenyl, or (R(sup 2)R(sup 3) single bond Si single bond B single bond)(sub n) and R(sup 2) and R(sup 3) are each independently selected from hydrogen, lower alkyl, vinyl, cycloalkyl, or aryl, n is an integer between 1 and 100; p is an integer between 1 and 100; and q is an integer between 1 and 100. These materials are prepared by combining an organo borohalide of the formula R(sup 4) single bond B single bond (X sup 1) (sub 2) where R(sup 4) is selected from halogen, lower alkyl, cycloalkyl, or aryl, and an organo halosilane of the formula: R(sup 2)(R sup 3)Si(X sup 2)(sub 2) where R(sup 2) and R (sup 3) are each independently selected from lower alkyl, cycloalkyl, or aryl, and X(sup 1) and X(sup 2) are each independently selected from halogen, in an anhydrous aprotic solvent having a boiling point at ambient pressure of not greater than 160 C with in excess of four equivalents of an alkali metal, heating the reaction mixture and recovering the polyorgano borosilane. These silicon boron polymers are useful to generate high-temperature ceramic materials, such as SiC, SiB4, and B4C, upon thermal degradation above 600 C

Preparation of B-trichloroborazine

The present invention relates to a method of preparing B-trichloroborazine. Generally, the method includes the combination of gaseous boron trichloride in an anhydrous aprotic organic solvent followed by addition of excess gaseous ammonia at ambient temperature or below. The reaction mixture is heated to about 100 to 140 C followed by cooling, removal of the solid ammonium chloride at ambient temperature, distillation of the solvent under vacuum if necessary at a temperature of up to about 112 C, and recovery of the B-trichloroborazine. Solvents include toluene, benzene, xylene, chlorinated hydrocarbons, chlorinated aromatic compounds, or mixtures thereof. Toluene is a preferred solvent. The process provides a convenient synthesis of a material which often decomposes on standing. B-trichloroborazine is useful in a number of chemical reactions, and particularly in the formation of high temperature inorganic polymers and polymer precursors

Analysis of 10086 Microarray Gene Expression Data Uncovers Genes that Subclassify Breast Cancer Intrinsic Subtypes

Breast cancer is a complex disease comprising molecularly distinct subtypes. The prognosis and treatment differ between subtypes; thus, it is important to distinguish one subtype from another. In this chapter, we make use of high-throughput microarray dataset to perform breast cancer subtyping of 10086 samples. Aside from the four major subtypes, that is, Basal-like, HER2-enriched, luminal A, and luminal B, we defined a normal-like subtype that has a gene expression profile similar to that found in normal and adjacent normal breast samples. Also, a group of luminal B-like samples with better prognosis was distinguished from the high-risk luminal B breast cancer. We additionally identified 33 surface-protein encoding genes whose gene expression profiles were associated with survival outcomes. We believe these genes are potential therapeutic targets and diagnostic biomarkers for breast cancer

Light-weight ceramic insulation

Ultra-high temperature, light-weight, ceramic insulation such as ceramic tile is obtained by pyrolyzing a siloxane gel derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes may contain also an effective amount of a mono- or trialkoxy silane to obtain the siloxane gel. The siloxane gel is dried at ambient pressures to form a siloxane ceramic precursor without significant shrinkage. The siloxane ceramic precursor is subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation, can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C. and is particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications

Light-weight black ceramic insulation

Ultra-high temperature, light-weight, black ceramic insulation having a density ranging from about 0.12 g/cc. to 0.6 g/cc. such as ceramic tile is obtained by pyrolyzing siloxane gels derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes also may contain an effective amount of a mono- or trialkoxy silane to obtain the siloxane gels. The siloxane gels are dried at ambient temperatures and pressures to form siloxane ceramic precursors without significant shrinkage. The siloxane ceramic precursors are subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C., and particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications

I. Electron Microscope Heteroduplex Analysis of DNA Sequences in F-Prime Factors. II. Electron Microscope Studies of λ and Mu Prophages. III. An Electron Microscope Study of Sindbis Virus RNA

This thesis is composed of three parts. Part I is concerned with studies of the DNA sequences of several F-prime factors and the sequence relations among them using electron microscope heteroduplex methods. It was found that the DNA sequence of the F factor can be roughly divided into three regions: 1) a region about one-fourth of the molecule which is concerned with the fertility functions of the F factor. 2) a region about one-third of the molecule which is rich in A+T sequence and contains the sequences used to interact with the bacterial chromosome for the integration or excision of F factor DNA. J) a region which contains the genes for autonomous replication and female phage resistance and the structural element for conjugal transfer. The structure of the bacterial DNA carried in several classical episomes, F100, F152, F8 and some of their derivatives was studied extensively. Bacterial markers between fep and uvrB were analyzed both genetically and physically. A method was developed to reconstruct the original episomes from their deletion variants. The results confirm the history that F100 and F152 were derived from the same Hfr. The formation of a new episome, F80, from F8 suggested that there is a hot spot in the E. coli chromosome for the recombination with F sequence between 93.2 and 94.5/0.0F. In part II, the structures of λ and Mu prophages and Mu phage DNA were studied. The λ prophage carried in an F-prime factor was found by electron microscope heteroduplex analysis to be circularly permuted relative to the vegetative viral DNA. On the other hand, Mu prophage DNA was shown to be collinear with the viral DNA. The integrated Mu prophage DNA was used as a marker for physical mapping of bacterial genes in E. coli. Sequence heterogeneity in Mu phage and prophage DNA's was also studied. The G loop heterogeneity was found to be present in both phage and prophage DNA.'s and was shown to be due to sequence inversion. The heterogeneous split ends sequences were found to be absent in the several prophages studied. Part III contains an electron microscope study of viral RNA of Sindbis virus and a method for mapping poly A sequences in RNA molecules. Under weak denaturing conditions Sindbis virus RNA appears in circular form with a double stranded "handle" of about 250 nucleotides long. This implies that Sindbis RNA contains complementary sequences at or near the ends of the molecule. A technique using glyoxal as a denaturing agent for mapping polyA sequences in RNA was developed. Glyoxal attaches to guanine base irreversibly and thus removes the secondary structure of RNA without inhibiting the renaturation capacity of polyA sequences in the molecule. A polyA sequence was found at or near one end of Sindbis RNA by this method.</p

Structural panels

Vinyl pyridines including vinyl stilbazole materials and vinyl styrylpyridine oligomer materials are disclosed. These vinylpyridines form copolymers with bismaleimides which copolymers have good fire retardancy and decreased brittleness. The cure temperatures of the copolymers are substantially below the cure temperatures of the bismaleimides alone. Reinforced composites made from the cured copolymers are disclosed as well

Vinyl stilbazoles

Vinyl pyridines including vinyl stilbazole materials and vinyl styrylpyridine oligomer materials are disclosed. These vinylpyridines form copolymers with bismaleimides which copolymers have good fire retardancy and decreased brittleness. The cure temperatures of the copolymers are substantially below the cure temperatures of the bismaleimides alone. Reinforced composites made from the cured copolymers are disclosed as well