Convection Patterns in Liquid Oxide Films on ZrB2–SiC Composites Oxidized at a High Temperature

During the high-temperature oxidation of ZrB₂–SiC composites, liquid boron oxide (B₂O₃) is formed at the zirconium diboride–zirconium oxide interface and transported through the overlying layer of silica liquid by convection, forming distinct convection cells arranged like the petals of a flower. The convection cells are localized by a viscous fingering phenomenon, as the fluid B₂O₃ rich liquid solution rises through the viscous silica layer. The upwelling B₂O₃ rich liquid contains dissolved zirconium dioxide, which deposits in the center of the flower-like structure as the B₂O₃ evaporates. The driving force for the B₂O₃ liquid flow is the volume increase upon oxidation of ZrB₂. Convective transport of B₂O₃ liquids suggests a novel mechanism for the high-temperature oxidation of these materials.     

Two human neonatal IgM antibodies encoded by different variable-region genes bind the same linear peptide: evidence for a stereotyped repertoire of epitope recognition

Two monoclonal IgM Abs have been produced from lymphocytes isolated from two human umbilical cord bloods. These mAbs recognize a conformational epitope present in a CNBr digestion fraction of lactoferrin. Linear epitopes recognized by each mAb were selected from several phage display peptide libraries. In each case, phages displaying a peptide with a motif defined by [WF],G,[EQS],N were recovered. Phages displaying that motif bound equally well to either mAb but did not bind to control IgM. A peptide bearing this motif competed with the phage-displayed peptides for binding to either mAb. The same peptide also competes with a component of the CNBr digestion fraction of lactoferrin for Ab binding in ELISA. The Abs use different families of VH, JH, and VK gene cassettes but use the same JK cassette. All segments are virtually identical to their germline gene counterparts. This work provides further evidence that certain innate specificities are stereotyped among individuals.     

Uncorrelated multisymbol signals for MIMO system identification

This paper presents a new approach to the system identification of a two-input two-output multivariable system. In a similar manner to that used for the single-input/single-output system, the multi-input multi-output (MIMO) system response may be obtained directly from measured input output frequency responses. An investigation of compact multifrequency data measurement signals, which have been extensively cataloged by the authors, has provided compact multifrequency ternary and quaternary input signals that have uncorrelated spectra. They are powerful multisymbol, multilevel computer generated measurement signals whose signal power is concentrated in either two or three dominant harmonics. As the signals, which are given in this paper, have six, seven, or eight symbols in their measurement codes, both the computation time for the frequency estimates and the experimental time are minimized. Two multifrequency quaternary signals with uncorrelated spectra are used to identify a simulated distillation column. It is shown that the cross coupling terms between the measurement channels may be removed by these digital measurement signals with the same number of symbols but different measurement codes     

Some considerations of wear and hardfacing materials

This paper is a brief review of various aspects pertaining to Wear Processes and Hardfacing Materials. It attempts to clarify the necessary requirements for realising the correct selection of Hardfacing Materials to mitigate Wear Processes.

It considers such topics as the economics of hardfacing materials where account is taken of various factors such as:

1. (a) cost of repair of replacement;

2. (b) time between scheduled plant shutdowns; and

3. (c) financial overheads, wear processes and testing procedures and material selection for wear resistance.

The effectiveness of surface treatments and coatings in combatting wear are discussed as well as the microstructural influence on wear resistance. Finally outlines for the classification of the various hardfacing materials are assessed.     

Sequential arousal and airway-defensive behavior of infants in asphyxial sleep environments

Infants are prone to accidental asphyxiation. Therefore, we studied airway-defensive behaviors and their relationship to spontaneous arousal behavior in 41 healthy sleeping infants (2-26 wk old), using two protocols: 1) infant was rebreathing expired air, face covered by bedding material; and 2) infant was exposed to hypercarbia, face uncovered. Multiple measurements of respiratory and motor activities were recorded (video, polygraph). The infants' response to increasing hypercarbia consisted of four highly stereotyped behaviors: sighs (augmented breaths), startles, thrashing limb movements, and full arousal (eyes open, cry). These behaviors occurred abruptly in self-limited clusters of activity and always in the same sequence: first a sigh coupled with a startle, then thrashing, then full arousal. Incomplete sequences (initial behaviors only) occurred far more frequently than the complete sequence and were variably effective in removing the bedding covering the airway. In both protocols, as inspired CO2 increased, incomplete arousal sequences recurred periodically and with increasing frequency and complexity until the infant either succeeded in clearing his/her airway or was completely aroused. Spontaneous arousal sequences, identical to those occurring during hypercarbia, occurred periodically during sleep. This observation suggests that the infant's airway-defensive responses to hypercarbia consist of an increase in the frequency and complexity of an endogenously regulated, periodically occurring sequence of arousal behaviors.     

Isolation of a novel Kunitz family protease inhibitor in association with Tethya hemolysin from the sponge Tethya ingalli

Aqueous extracts from the New Zealand sponge Tethya ingalli (Hadromerida) displayed potent cytotoxicity in the NCI's 60-cell-line human tumor panel. Fractionation of the extract by ammonium sulfate precipitation, gel filtration, ultrafiltration, and both hydrophobic interaction and reversed-phase chromatography resulted in the isolation of two biologically active proteins. The first protein, Tethya protease inhibitor (TPI), which was purified to homogeneity, inhibited trypsin with an EC50 of 65 nM. TPI had a molecular mass of 11,431 Da, and an isoelectric point of 8.2. A partial N-terminal amino acid sequence determined for TPI showed significant homology with protease inhibitors of the Kunitz family. The second isolated protein displayed potent cytotoxicity, with pronounced selectivity for certain tumor cell lines (e.g., ovarian, renal, CNS, and breast). The latter protein, which had an apparent molecular weight of 21 kDa (SDS-PAGE), also lysed human red blood cells (EC50 of 39 nM) and was similar to a hemolysin previously isolated from the sponge Tethya lycinurium.     

Memory span procedures in Alzheimer's disease.

In a working memory framework, the forward memory span involves a subsidiary system that maintains information, and the backward span relies on a central executive system (CES) that allocates processing resources. The authors hypothesized that a measure of the CES derived from the backward span would distinguish Alzheimer's disease (AD) patients (n&≠&?9) from elderly controls without dementia (n&≠&?9), vary as a function of disease severity, and underlie other cognitive disturbances. Memory span procedures were Digit Span Forward and Backward and Visual Memory Span Forward and Backward. Derived CES measures discriminated between groups, predicted dementia severity, and predicted performance on some of the cognitive tasks examined. However, working memory subsidiary systems also appeared to be affected in AD, and some cognitive deficits in AD were independent of working memory disturbances. The visual memory span backward was the best predictor of group and of dementia severity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)