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The effectiveness of monazite (LaPO4) in providing an oxidation‐resistant weak fiber/matrix interface was evaluated in a fiber roving/thin coating/ceramic‐matrix composite with >20% fiber volume fraction. Nextel™ 610/monazite/alumina composites were fabricated and tensile tested after isothermal exposures of up to 1000 h. Some strength loss was seen after short‐term exposures (1100°–1200°C/5–250 h); however, no further loss was observed after 1000 h at 1200°C. Conversely, control samples containing uncoated fiber displayed >70% strength losses after only 5 h at 1200°C. Fiber pullout was seen in monazite‐containing samples even after 1000 h at 1200°C. Debonding was predominantly in the coating or at either the fiber/coating or coating/matrix interface. Push‐out testing confirmed the weakness of the monazite coating interface.

S U M M A R YGastrin-releasing peptide (GRP) and its receptor (GRP-R) are not normally expressed by epithelial cells lining the colon but are aberrantly expressed in cancer, where they act as morphogens and regulate tumor cell differentiation. Studies of colon cancer formation in mice genetically incapable of synthesizing GRP-R suggested that this receptor's morphogenic properties were mediated via focal adhesion kinase (FAK). We therefore set out to determine the presence of both total and phosphorylated forms of FAK in human colon cancer specimens as a function of tumor cell differentiation and GRP/GRP-R co-expression. Ten colon cancers containing 25 regions of distinct differentiation were randomly selected from our GI Cancer Tumor Bank. All specimens were immunohistochemically probed using antibodies recognizing GRP, GRP-R, total FAK, and FAK specifically phosphorylated at tyrosine (Y) 397, 407, 576, 577, 861, and 925. Antibody-specific chromogen was determined by quantitative immunohistochemistry (IHC) for each region of defined differentiation. Here we confirm that GRP/GRP-R co-expression is a function of differentiation, with highest levels observed in well-differentiated tumor cells. We also show that the amount of total FAK and of FAK phosphorylated at Y397 and Y407 tightly correlates with differentiation and with the amount of GRP/GRP-R co-expression. These findings are consistent with GRP/GRP-R acting as a morphogen by activating FAK, and suggest that this occurs via phosphorylation of this enzyme at two specific tyrosine residues.

Formation of fibrillar patterns of fibronectin on polymer substrates with gradated physicochemical surface properties was analysed during early stages of endothelial cell adhesion. Fibronectin was pre-adsorbed onto three maleic anhydride copolymer thin films with distinct differences in the protein adsorption strength as verified by heteroexchange experiments. The evolved micrometer scale fibrillar patterns of fibronectin on the compared polymer surfaces were characterized after 50 min of cellular reorganization by an auto-correlation analysis using fluorescence microscopy data. Statistical analysis revealed a decrease of the typical spacings of the fibronectin fibrils from 2.6 to 1.8 mum with decreasing fibronectin adsorption strength to the substrate. Size and density of focal adhesions correlated with this dependence of the fibronectin fibril pattern. From these data a model was developed relating the fibronectin fibril pattern to the fibronectin-substrate adsorption strength through the cytoskeletal force regulation mechanism of the cell.

Hafnium diboride (HfB2) powder has been synthesized via a sol–gel‐based route using phenolic resin, hafnium chloride, and boric acid as the source of carbon, hafnium, and boron, respectively, though a small number of comparative experiments involved amorphous boron as boron source. The effects of heat‐treatment dwell time and hafnium:carbon (Hf:C) and hafnium:boron (Hf:B) molar ratio on the purity and morphology of the final powder have been studied and the mechanism of HfB2 formation investigated using several techniques. The results showed that while temperatures as low as 1300°C could be used to produce HfB2 particles, the heat treatment needed to last for about 25 h. This in turn resulted in anisotropic particle growth along the c‐axis of the HfB2 crystals yielding tube‐like structures of about 10 μm long. Equiaxed particles 1–2 μm in size were obtained when the precursor was heat treated at 1600°C for 2 h. The reaction mechanism involved boro/carbothermal reduction and the indications were that the formation of HfB2 at 1300°C is through the intermediate formation of an amorphous B or boron suboxides, although at higher temperatures more than one reaction mechanism may be active.

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Shell Effect and a-Decay ProbabilityFor the prediction of half-lives for e-decay a semiempirical equation is given. Taking into account a mean excitation energy of the daughter nuclei the constants in the equation for the e-half-lives were reevaluated using the latest published decay schemes. The ratios of experimental and calculated half-lives show a systematic behaviour if plotted versus the shell effects. Using this correlation the e-half-lives for unknown nuclides can be predicted with an improved accuracy.

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