Ubiquitination of protein kinase C-alpha and degradation by the proteasome

Bryostatins and phorbol esters acutely activate and subsequently down-regulate protein kinase C (PKC) by inducing its proteolysis via an unknown pathway. Here we show that treatment of renal epithelial cells with bryostatin 1 (Bryo) produced novel PKC-alpha species, which were larger than the native protein (80 kDa). The >80 kDa PKC-alpha species contained Ubi as indicated by immunostaining and accumulated in the presence of lactacystin, a selective inhibitor of proteolysis by the proteasome. In vitro experiments with 125I-ubiquitin and membranes from Bryo-treated cells showed that PKC-alpha became ubiquitinated by a reaction that depended on ATP and a cytosolic fraction. Lactacystin or a peptidyl aldehyde, Bz-Gly-Leu-Ala-leucinal, which inhibits certain proteinase activities of the proteasome, inhibited Bryo-evoked disappearance of PKC-alpha protein from the cells. Lacta preserved Bryo-induced 32P-labeled PKC-alpha indicating that the proteasome inhibitor spared activated enzyme from down-regulation in vivo. These findings show that Bryo induces the degradation of PKC-alpha by the ubiquitin-proteasome complex.     

Electrochemical investigation of the surface-modifying roles of guanidine carbonate in chemical mechanical planarization of tantalum

The fabrication of interconnect structures for semiconductor devices requires low down-pressure chemical mechanical planarization (CMP) of Ta barrier layers. Guanidine carbonate (GC) serves as an effective surface-complexing agent for such CMP applications, where the rate of Ta removal can be chemically controlled through pH-tuned selectivity with respect to the removal of Cu lines. Electrochemical techniques are employed in this work to study the surface-modifying roles of GC that make this chemical an attractive complexing agent for Ta CMP. In addition, the effects of including H₂O₂ (an oxidizer) and dodecyl benzene sulfonic acid (DBSA, a dissolution inhibitor for Cu) in GC-based CMP solutions are investigated to examine the selective CMP mechanisms of Ta and Cu in these solutions. The results suggest that the removal of Ta is supported in part by structurally weak guanidinium–tantalic-acid surface complexes formed on Ta/Ta₂O₅. The bicarbonate/carbonate anions of GC also facilitate Ta removal through the generation of ion-incorporated tantalum pentoxide. DBSA strongly affects the CMP chemistry of Cu, but exhibits relatively weaker effects on the surface activity of Ta, and thus plays a vital role in dictating the selectivity of Ta:Cu polish rates.     

Hot Corrosion of Metals and Alloys

When metals and alloys are used at high temperatures, especially in combustion processes, deposits often accumulate on the metal surfaces and affect the oxidation processes. This paper is concerned with deposit-induced accelerated corrosion, or hot corrosion, of metals and alloys. Initially, the characteristics of hot corrosion are identified for Na₂SO₄ deposits in terms of the factors that influence the reaction process. It is shown that hot corrosion consists of initiation or incubation and propagation stages. During the initiation or incubation stage, the deposit is shown to not have a significant effect on the corrosion processes, but it is causing conditions to develop whereby the propagation stage characteristics are determined with attendant large increases in the corrosion rates. Type I, high temperature hot corrosion and Type II, low temperature hot corrosion are then described in terms of historical mechanistic perspectives. The dependence of Type I and Type II hot corrosion on temperature and SO₃ partial pressure is discussed along with future work that is needed in order to more completely understand these hot corrosion processes along with the effects of some elements such as Cr, Al, Mo, Co and Pt.     

High-speed 1.3 μm GaInAs detectors fabricated on GaAs substrates

High-speed interdigitated metal-semiconductor-metal detectors have been fabricated on non-lattice-matched, semi-insulating, GaAs substrates using two GaInAs layers of differing indium concentrations to accommodate most of the lattice mismatch by interface misfit dislocations. Bandwidths as high as 3 GHz were measured with none of the detrimental low-frequency gain usually observed in this type of device. This is attributed to the inhibition of the surface trapping of photoinduced carriers by a graded pseudomorphic layer at the surface     

Antineoplastic agents. 398. Isolation and structure elucidation of cephalostatins 18 and 19

Continued investigation of murine leukemia (P-388) active fractions from the African marine worm Cephalodiscus gilchristi has resulted in the discovery of cephalostatins 18 (1b) and 19 (1c). The structures were determined by interpretation of their highfield (500 MHz) 1H, 13C, and 2D NMR and HRMS. Both of these new methoxy steroidal alkaloids exhibited strong activity against the murine P-388 lymphocytic leukemia cell line (ED50 ca. 10(-3) microg/mL), a mini panel of human cancer cell lines (GI50 <10(-3) microg/mL), and the U.S. National Cancer Institute's 60 human cancer cell line panel (mean panel GI50 ca. 10(-9) M).     

Developmental trajectories of childhood disruptive behaviors and adolescent delinquency: A six-site, cross-national study.

This study used data from 6 sites and 3 countries to examine the developmental course of physical aggression in childhood and to analyze its linkage to violent and nonviolent offending outcomes in adolescence. The results indicate that among boys there is continuity in problem behavior from childhood to adolescence and that such continuity is especially acute when early problem behavior takes the form of physical aggression. Chronic physical aggression during the elementary school years specifically increases the risk for continued physical violence as well as other nonviolent forms of delinquency during adolescence. However, this conclusion is reserved primarily for boys, because the results indicate no clear linkage between childhood physical aggression and adolescent offending among female samples despite notable similarities across male and female samples in the developmental course of physical aggression in childhood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of angle of incidence on the combined erosion-oxidation attack of nickel and cobalt

The combined erosion-oxidation of cobalt and nickel at 600 and 780°C over a range of particle-impact angles has been studied by using weight change vs. time measurements and extensive morphological and microstructural characterization of exposed specimens. The oxidation process has been found to affect the angular dependence of the degradation rates. The effect is especially significant at low-impact angles where ripples and flakes are developed upon the surfaces of specimens.     

Widhelm and Lessing Revisited: An Alternative Markovian Model for Processing Systems with Imperfect Review

An earlier model due to Widhelm and Lessing [10] is discussed briefly. Some criticisms are advanced, indicating that it does not represent adequately situations that may be found in industry. The model is shown to be a derivative of a more general “super model” which is unlikely to be workable in practice. A simpler alternative is developed. A verification exercise is reported for this latter alternative, based on data from a pharmaceutical organization, and some uses of the model are indicated, based on data from a company in the aerospace industry.